Patent Application
20160326272
The invention relates to hydrogenated nitrile rubbers which have either a zero content or a reduced content of phosphines or diphosphines and additionally contain phosphine oxide or diphosphine oxide and have a specific halogen content, to a process for production thereof, to vulcanizable mixtures based on the hydrogenated nitrile rubbers, and to vulcanizates obtained in that way.
Nitrile rubbers are co- and terpolymers of at least one unsaturated nitrile monomer, at least one conjugated diene and optionally one or more copolymerizable monomers. Processes for producing nitrile rubber and processes for hydrogenating nitrile rubber in suitable organic solvents are known from the literature (e.g. Ullmann's Encyclopedia of Industrial Chemistry, VCH Verlagsgesellschaft, Weinheim, 1993, p. 255-261 and p. 320-324).
Hydrogenated nitrile rubber, abbreviated to “HNBR”, is understood to mean rubbers which are obtained from nitrile rubbers, abbreviated to “NBR”, by hydrogenation. Correspondingly, in HNBR, the C═C double bonds of the copolymerized diene units are fully or partly hydrogenated. The hydrogenation level of the copolymerized diene units is typically within a range from 50 to 100%. Those skilled in the art refer to “fully hydrogenated types” even when the residual double bond content (“RDB”) is not more than about 0.9%. The HNBR types commercially available on the market typically have a Mooney viscosity (ML 1+4 at 100° C.) in the range from 10 to 120 Mooney units.
Hydrogenated nitrile rubber is a specialty rubber having a very good heat resistance, excellent resistance to ozone and chemicals and excellent oil resistance. The aforementioned physical and chemical properties of HNBR are combined with very good mechanical properties, especially a high abrasion resistance.
Because of this profile of properties, HNBR has found wide use in a wide variety of different areas of application. HNBR is used, for example, for seals, hoses, drive belts, cable sheaths, roller coverings and damping elements in the automotive sector, and also for stators, well seals and valve seals in the oil production sector, and for numerous parts in the aviation industry, the electrical industry, in mechanical engineering and in shipbuilding.
A major role is played by vulcanizates of hydrogenated nitrile rubber having a high modulus level (measured as the stress value at various elongations) and low compression set, especially after long storage periods at high temperatures. This combination of properties is important in fields of use in which high resilience forces are required to ensure that the rubber articles will function both under static and under dynamic stress, including after long periods and possibly high temperatures. This applies especially to different seals such as O-rings, flange seals, shaft sealing rings, stators in rotor/stator pumps, valve shaft seals, gasket sleeves such as axle boots, hose seals, engine bearings, bridge bearings and well seals (blowout preventers). In addition, vulcanizates having a high modulus are important, for example, for articles under dynamic stress, especially for belts such as drive belts and control belts, for example toothed belts, and also for roller coverings.
The level obtained to date in the mechanical properties of HNBR-based vulcanizates, especially in relation to the modulus level and compression set, is still unsatisfactory.
For the hydrogenation of nitrile rubber with homogeneously soluble rhodium and/or ruthenium hydrogenation catalysts, the addition of phosphines or diphosphines as a cocatalyst has been found to be useful. Preference is given to the use of triphenylphosphine (“TPP”). This use of a cocatalyst has a number of positive effects: a reduction in the pressure needed for the hydrogenation is enabled; in addition, an increase in the hydrogenation rate (space/time yield) and a reduction in the amount of hydrogenation catalyst needed for the hydrogenation can be achieved. On the other hand, residual amounts of the phosphine or diphosphine remaining in the hydrogenated nitrile rubber have adverse effects on the vulcanizate properties, especially the modulus level and compression set.
DE 25 39 132 A describes a process for hydrogenating random acrylonitrile/butadiene copolymers. For the hydrogenation, the complex of a mono- or trivalent rhodium(I) halide is used in combination with 5 to 25% by weight of triphenylphosphine, with use of 10 phr of triphenylphosphine in each of the examples, DE 25 39 132 A does not vary the amount of triphenylphosphine. Nor are any vulcanizates produced on the basis of the hydrogenated nitrile rubbers or characterized with respect to the properties. DE 25 39 132 A does not give any figures for the contents of triphenylphosphine that remain in the worked-up hydrogenated nitrile rubber after the hydrogenation. Nor is there any examination, moreover, of whether and, if so, what influence TPP has on the properties, especially the modulus level and compression set of vulcanizates produced therefrom. Furthermore, there is no indication whatsoever as to the removal of the TPP used in the hydrogenation.
In U.S. Pat. No. 4,965,323, the compression set of HNBR-based vulcanizates which are obtained by peroxidic vulcanization or by sulphur vulcanization is improved by contacting the nitrile rubber after the polymerization or after the hydrogenation with an aqueous alkali solution or the aqueous solution of an amine. In example 1, rubber crumbs that are obtained after removal of the solvent are washed in a separate process step with aqueous sodium carbonate solutions of different concentration. The pH of an aqueous THF solution obtained by dissolving 3 g of the rubber in 100 ml of THF and adding 1 ml of water while stirring is used as a measure of the alkali content. The pH is determined by means of a glass electrode at 20° C. For the production of vulcanizates of the hydrogenated nitrile rubber having low compression set, the pH of aqueous THF solution should be >5, preferably >5.5, more preferably >6. In U.S. Pat. No. 4,965,323, there is no pointer to the dependence of compression set on the amount of TPP used in the hydrogenation, or to improvement of the compression set by removal of TPP after the hydrogenation.
U.S. Pat. No. 4,503,196 describes a process for hydrogenating nitrile rubber using rhodium catalysts of the (H)Rh(L)3 or (H)Rh(L)4 type. L represents phosphine or arsine ligands. It is a feature of the hydrogenation process that no additions of the ligands as cocatalysts are required for the hydrogenation, although the hydrogenation is effected with relatively high amounts of catalyst (2.5 to 40% by weight). For the isolation of the hydrogenated nitrile rubber from the chlorobenzene solution, the hydrogenated solution is cooled and the rubber is coagulated by addition of isopropanol. U.S. Pat. No. 4,503,196 does not give any information about the vulcanizate properties of the hydrogenated nitrile rubbers that result in this process. For this reason, U.S. Pat. No. 4,503,196 does not give any teaching about the production of hydrogenated nitrile rubber, by which vulcanizates having a high modulus level and low compression set are obtained.
DE-A-3 921 264 describes the production of hydrogenated nitrile rubber which, after peroxidic crosslinking, gives vulcanizates having low compression set. For this purpose, ruthenium catalysts of a wide variety of different chemical constitutions are used for the hydrogenation, with use of a solvent mixture of a C3-C6 ketone and a secondary or tertiary C3-C6 alcohol in the hydrogenation. The proportion of the secondary or tertiary alcohol in the solvent mixture is said to be 2 to 60% by weight. According to DE-A-3 921 264, two phases can be formed during the hydrogenation or in the course of cooling of the hydrogenated solution. As a consequence, the desired hydrogenation levels are not attained and/or the hydrogenated nitrile rubber gelates during the hydrogenation. The process described in DE-A-3 921 264 is not broadly applicable, since the phase separation which takes place in the course of the hydrogenation and the gelation depends on various parameters in an unpredictable manner. These include the acrylonitrile content and the molar mass of the nitrile rubber feedstock, the composition of the solvent mixture, the solids content of the polymer solution in the hydrogenation, the hydrogenation level and the temperature in the hydrogenation. In the course of cooling of the polymer solution after the hydrogenation or in the course of storage of the polymer solution too, there may be unexpected phase separation and contamination of the corresponding plant components or vessels.
WO-A-2004/101671 shows that hydrogenated carboxylated nitrile/butadiene rubber containing TPP in molecular dispersion can be used advantageously as a crosslinker for elastomers or plastics and as adhesives. On the basis of WO-A-2004/101671, in which the necessity of the presence of TPP is explicitly pointed out, no teaching as to the improvement of compression set and moduli of vulcanizates can be inferred.
EP-A-1 894 946 describes a process for metathesis degradation of NBR, in which the activity of the metathesis catalyst is enhanced by TPP additions. Based on the metathesis catalyst, 0.01 to 1 equivalent of phosphine, for example TPP, is used. Nitrile rubbers of reduced molecular weight prepared in this way can, according to EP-A-1 894 946, be hydrogenated using methods known from the prior art. The catalyst used may, for example, be the Wilkinson catalyst in the presence of cocatalysts such as TPP. There is no information about the vulcanizate properties and the optimization thereof, especially with regard to the level of modulus and compression set of the hydrogenated nitrile rubbers obtained in the hydrogenation.
Nor does EP-A-1 083 197 describe any measures for reducing the compression set for vulcanizates which are used for production of roller coverings. The aim is achieved by using the methacrylates of polyhydric alcohols, e.g. trimethylolpropane trimethacrylate, in the production of the rubber mixtures. Nor does EP-A-1 083 197 give any pointer to improvement of the compression set or moduli by eliminating the harmful influence caused by triphenylphosphine.
EP-A-1 524 277 describes an ultrafiltration process for removing low molecular weight constituents from rubbers. For this purpose, the rubbers are dissolved in an organic solvent and subjected to an ultrafiltration process. The process is suitable both for removal of emulsifier residues from nitrile rubber and for removal of catalyst residues from hydrogenated nitrile rubber. According to Example 2 of EP-A-1 524 277, it is possible with the aid of this method to reduce the phosphorus content of hydrogenated nitrile rubber from 1300 mg/kg to 120 mg/kg. EP-A-1 524 277 does not give any information as to whether this process, which is additionally costly in economic terms, enables an improvement in the modulus level and compression set of vulcanizates of hydrogenated nitrile rubbers.
EP-A-0 134 023 describes a process for hydrogenating NBR with 0.05 to 0.6% by weight, based on rubber solids, of tris(triphenylphosphine)rhodium(I) halide as catalyst, in which not more than 2% by weight, likewise based on rubber solids, of triphenylphosphine is added. The examples in Table 3) show that an increase in the amount of triphenylphosphine to up to 5% by weight leads to a deterioration in important properties of peroxidically vulcanized hydrogenated nitrile rubbers. For instance, there is a decrease in the modulus values at 100%, 200% and 300% elongation, and in the hardness at 23° C. There is an increase in the elongation at break and compression set values after storage at 23° C. for 70 h, at 125° C. for 70 h and at 150° C. for 70 h. In order to limit the harmful influence of TPP, according to the teaching of EP-A-134 023, the amount of TPP used in the hydrogenation is restricted. Disadvantageously, it is then necessary in this hydrogenation, for the purpose of achieving equal hydrogenation times, to use higher amounts of catalyst and hence of costly rhodium metal. EP-A-0 134 023 does not give any teaching as to the removal of the TPP after the hydrogenation.
In U.S. Pat. No. 5,244,965, nitrile rubber is hydrogenated using tetrakis(triphenylphosphine)hydridorhodium in the presence of considerable molar excesses of TPP. Because of suspected adverse effects of triphenylphosphine on the properties of the vulcanized rubber (page 1 lines 26-28: “Furthermore, there is some indication that phosphines cause problems with polymer vulcanization”), TPP is removed after the hydrogenation of the rubber solution. For this purpose, TPP is converted to the corresponding phosphonium salts with addition of equimolar amounts of organic halogen compounds suitable for formation of triphenylphosphonium salts, especially methyl bromide, ethyl bromide, benzyl chloride or benzyl bromide, at temperatures of 70°-120° C. within a period of 4.8 h. In the course of cooling of the polymer solution down to 20° C. to 40° C. the phosphonium salts precipitate out and are subsequently separated mechanically from the polymer solution by filtration or by sedimentation. It is shown that triphenylphosphine oxide is present both in the hydrogenated nitrile rubber produced in accordance with the invention and in the corresponding comparative experiment, which has been produced without additions of organic halides. The process described in U.S. Pat. No. 5,244,965 is disadvantageous from an economic point of view, since long tank occupation times are required for the conversion of the TPP to the triphenylphosphonium salt. Moreover, the separation of the phosphonium salt from the high-viscosity polymer solution by sedimentation or filtration is complex in terms of process technology. Secondly, it is not advantageous that the mixture has to be cooled and also diluted in order to separate out the triphenylphosphonium salt formed. Triphenylphosphonium halide additionally crystallizes in an irreproducible manner. It is often obtained in very finely divided form, which complicates the removal from the solution and causes an incomplete removal from the polymer solution, such that relatively large residual amounts of the triphenylphosphonium halides inevitably remain in the hydrogenated nitrile rubber. This becomes clear in Example 2, Experiments 1) and 2) (Table 1) of U.S. Pat. No. 5,344,965. According to Example 2, for each of Experiments 1) and 2), 5.5 g (20.87 mmol) of TPP are used per 100 g of rubber; the further addition of TPP likewise described in Example 2 is incomprehensible in quantitative terms and cannot be taken into account in a quantitative assessment. According to Example 2, Experiment 1), 20.87 mmol of triphenylphosphine are reacted with 4 ml of methyl bromide. Given a density of 3.97 g/cm3, this corresponds to 15.88 g or 167.3 mmol of methyl bromide (molar mass of methyl bromide: 94.94 g/mol); in other words, in Experiment 1, a good 8-fold molar excess of methyl bromide based on TPP is used. Given quantitative conversion of TPP to triphenylmethylphosphonium bromide (molar mass: 356.8 g/mol), the result is a theoretical yield of 7.5 g of triphenylmethylphosphonium bromide. Since, according to Experiment 1), only 3.2 g of triphenylmethylphosphonium bromide are isolated, this corresponds to a yield of 43%. Taking account of the further TPP addition, which reacts with the excess of methyl bromide, the overall yield of isolated triphenylphosphonium bromide according to Example 2, Experiment 1) is well below 40%. According to Example 2. Experiment 2, based on 5.5 g (20.87 mmol) of TPP, 3 ml of ethyl bromide (density: 1.46 g/cm3), corresponding to 4.38 g (40.2 mmol), are used. Likewise without taking account of an unquantifiable further TPP addition, 7.8 g of triphenylethylphosphonium bromide (molar mass: 371.3 g/mol) are theoretically obtained from 5.5 g of TPP. The yield of 3.7 g described in Example 2, Experiment 2) thus corresponds at most to 47.4% of the theoretical yield. Because of the poor separation efficiency of the triphenylphosphonium bromide in the two experiments in Example 2), in the method for removing TPP described in U.S. Pat. No. 5,244,965, considerable amounts of triphenylphosphonium halides remain in the hydrogenated nitrile rubber, which lead to a deterioration in the vulcanizate properties, especially the corrosivity of seals produced therefrom. In U.S. Pat. No. 5,244,965, no positive influence of the TPP removal on the vulcanizate properties is detected.
In U.S. Pat. No. 5,244,965. Example 3, Table 2, figures are also given for contents of triphenylphosphine and triphenylphosphine oxide (“TPP═O”) in the hydrogenated nitrile rubber, which are summarized in the following table:
In U.S. Pat. No. 5,244,965, it remains unclear whether the removal or removability of the triphenylphosphonium salts is connected to the formation of triphenylphosphine oxide, how triphenylphosphine oxide is formed and whether this can be influenced. Furthermore, it remains unclear what influence TPP, triphenylphosphine oxide, phosphonium halides and residual amounts of the organic halides used for the removal have on the vulcanizate properties of hydrogenated nitrile rubbers. Overall, it is not possible to infer from the teaching of U.S. Pat. No. 5,244,965 how vulcanizates of the hydrogenated nitrile rubber having high modulus values and having a low compression set are to be produced.
In spite of extensive literature relating to production of hydrogenated nitrile rubbers, there are no hydrogenated nitrile rubbers available to date that firstly give vulcanizates having a good modulus level and good compression set values and can nevertheless at the same time be produced via hydrogenation processes having short reaction times using phosphine- or diphosphine-based cocatalysts with small amounts of catalyst. There are no known hydrogenated nitrile rubbers to date in which the adverse effects of the phosphine or diphosphine cocatalysts used in the hydrogenation on the respective vulcanizate properties, especially on the modulus level and compression set values after storage at high temperatures, can be avoided.
The problem addressed by the present invention was thus that of providing hydrogenated nitrile rubbers which give rise to vulcanizates having very good moduli and good compression set values, the latter especially after storage at high temperatures. The problem addressed by the present invention was additionally that of providing hydrogenated nitrile rubbers which simultaneously feature halogen contents that are not excessively high. The problem addressed by the present invention was also that of providing an economic process for production of such hydrogenated nitrile rubbers, in which the phosphine or diphosphine present as a cocatalyst in the hydrogenation is rendered harmless in a suitable manner after the hydrogenation, without having to remove any great amounts of halides or entrainment thereof into the hydrogenated nitrile rubber.
It has been found that, surprisingly, the improved properties of vulcanizates based on hydrogenated nitrile rubbers in the form of very good modulus values and improved compression set values, especially after storage at relatively high temperature, can be achieved when the hydrogenated nitrile rubber has a zero or reduced phosphine or diphosphine content, a particular phosphine oxide or diphosphine oxide content and a limited total halogen content. These hydrogenated nitrile rubbers can be obtained in an economic manner by converting the phosphine or diphosphine used in the hydrogenation to phosphine oxides or diphosphine oxides by means of suitable oxidizing agents after the hydrogenation, where the oxidizing agents and the amount thereof are selected such that the total halogen content in the hydrogenated nitrile rubber does not exceed 10 000 ppm. It is additionally surprising that the phosphine oxide or diphosphine oxide content does not have any adverse effect on the vulcanizate properties, but actually gives vulcanizates having very good modulus and compression set values.
The present invention provides hydrogenated nitrile rubbers having
The present invention further provides vulcanizable mixtures of these hydrogenated nitrile rubbers and processes for producing vulcanizates based thereon, and also the vulcanizates obtainable therewith, especially in the form of shaped bodies.
The present invention further provides a process for producing the Inventive hydrogenated nitrite rubbers having
R—OO—R′ (I)
HXOn, (II)
Where the term “substituted” is used in the context of this application, this means that a hydrogen atom on a given radical or atom is replaced by one of the groups specified in each case, with the proviso that the valency of the given atom is not exceeded and the substitution leads to a stable compound.
Because of the multitude of chemical formulae used, radicals given the same name or abbreviation are present in various formulae, but have, for the respective formula, only the general, preferred, more preferred or especially preferred meanings mentioned in each case in connection with this formula. If exceptions from the aforementioned principal are to apply, this is mentioned explicitly. Apart from this topic of radicals given the same abbreviation in different formulae, it is possible within the context of this application and invention to combine all the definitions given, in general terms or given within areas of preference, for parameters, definitions or elucidations with one another in any desired manner, i.e. including between the respective areas and areas of preference, and they are considered to be disclosed within this scope.
The inventive hydrogenated nitrile rubber has
The inventive hydrogenated nitrite rubber typically has a high hydrogenation degree, customarily in the range from 80 to 100%, preferably from 90 to 100%, more preferably from 92 to 100%, even more preferably from 94 to 100%. Alternatively preferred is a fully hydrogenated nitrile rubber which has a hydrogenation degree of 99.1% or greater.
The content of the phosphine/diphosphine component (i) as well as of the phosphine oxide/diphosphine oxide component (ii) is determined by means of gas chromatography in accordance with the method described in the example section with regard to the determination of the content of triphenylphosphane (“TPP”) and triphenylphosphane oxide (“TPPO”). The total halogen content is determined according to DIN 51408, Teil 2.
The phosphine component (I) typically has the general formula (1-a)
The R′ radicals in both of these formulae (1-a) and (1-b) may be unsubstituted or mono- or polysubstituted.
Such phosphines or diphosphines of the general formulae (1-a) and (1-b) are preparable by methods known to those skilled in the art or else are commercially available.
Alkyl radicals in the R′ radicals of the phosphines or diphosphines of the general formulae (1-a) and (1-b) are typically understood to mean straight-chain or branched C1-C30-alkyl radicals, preferably C1-C24-alkyl radicals, more preferably C1-C18-alkyl radicals. C1-C18-Alkyl comprises, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, neopentyl, 1-ethylpropyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethyl-1-methylpropyl, 1-ethyl-2-methylpropyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-hexadecyl and n-octadecyl.
Alkenyl radicals in the R′ radicals of the phosphines or diphosphines of the general formulae (1-a) and (1-b) are typically understood to mean C3-C30-alkenyl radicals, preferably C2-C20-alkenyl radicals. More preferably, an alkenyl radical is a vinyl radical or an allyl radical.
Alkadienyl radicals in the R′ radicals of the phosphines or diphosphines of the general formulae (1-a) and (1-b) are typically understood to mean C2-C30-alkadienyl radicals, preferably C2-C20-alkadienyl radicals. More preferably, an alkadienyl radical is butadienyl or pentadienyl.
Alkoxy radicals in the R′ radicals of the phosphines or diphosphines of the general formulae (1-a) and (1-b) are typically understood to mean C1-C20-alkoxy radicals, preferably C1-C10-alkoxy radicals, more preferably methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, ten-butoxy, n-pentoxy and n-hexoxy.
Aryl radicals in the R′ radicals of the phosphines or diphosphines of the general formulae (1-a) and (1-b) are typically understood to mean C5-C24-aryl radicals, preferably C6-C14-aryl radicals, more preferably C6-C12-aryl radicals. Examples of C5-C24-aryl are phenyl, o-, p- or m-tolyl, naphthyl, phenanthrenyl, anthracenyl and fluorenyl.
Heteroaryl radicals in the R″ radicals of the phosphines or diphosphines of the general formulae (1-a) and (1-b) have the same definition as given above for aryl radicals, except that one or more of the skeleton carbon atoms are replaced by a heteroatom selected from the group of nitrogen, sulphur and oxygen. Examples of such heteroaryl radicals are pyridinyl, oxazolyl, benzofuranyl, dibenzofuranyl and quinolinyl.
All the aforementioned alkyl, alkenyl, alkadienyl and alkoxy radicals may be unsubstituted or mono- or polysubstituted, for example by C5-C24-aryl radicals, preferably phenyl (in the case of alkyl radicals, this results, for example, in arylalkyl, preferably a phenylalkyl radical), halogen, preferably fluorine, chlorine or bromine, CN, OH, NH2 or NR″2 radicals where R″ in turn is C1-C30-alkyl or C5-C24-aryl.
Both the aryl radicals and the heteroaryl radicals are either unsubstituted or mono- or polysubstituted, for example by straight-chain or branched C1-C30-alkyl (resulting in what are called alkylaryl radicals), halogen, preferably fluorine, chlorine or bromine, sulphonate (SO3 Na), straight-chain or branched C1-C30-alkoxy, preferably methoxy or ethoxy, hydroxyl, NH2 or N(R″)3 radicals, where R″ in turn is straight-chain or branched C1-C30-alkyl or C5-C24-aryl, or by further C5-C24-aryl or -heteroaryl radicals, which results in bisaryl radicals, preferably biphenyl or binaphthyl, heteroarylaryl radicals, arylheteroaryl radicals or bisheteroaryl radicals. These C5-C24-aryl or -heteroaryl substituents too are again in turn either unsubstituted or mono- or polysubstituted by all the aforementioned substituents.
Cycloalkyl radicals in the R radicals of the phosphines or diphosphines of the general formulae (1-a) and (1-b) are typically understood to mean a C3-C20-cycloalkyl radical, preferably a C3-C8-cycloalkyl radical, more preferably cyclopentyl and cyclohexyl.
Cycloalkenyl radicals in the R′ radicals of the phosphines or diphosphines of the general formulae (1-a) and (1-b) are the same or different, have one C═C double bond in the ring skeleton and are typically C5-C8 cycloalkenyl, preferably cyclopentenyl and cyclohexenyl.
Cycloalkadienyl radicals in the R radicals of the phosphines or diphosphines of the general formulae (1-a) and (1-b) are the same or different, have two C═C double bonds in the ring skeleton and are typically C5-C8 cycloalkadienyl, preferably cyclopentadienyl or cyclohexadienyl.
The aforementioned cycloalkyl, cycloalkenyl and cycloalkadienyl radicals too are either unsubstituted or mono- or polysubstituted, for example by straight-chain or branched C1-C30-alkyl (the result is then what are called alkylaryl radicals), halogen, preferably fluorine, chlorine or bromine, sulphonate (SO3Na), straight-chain or branched C1-C30-alkoxy, preferably methoxy or ethoxy, hydroxyl, NH2 or NR″2 radicals, where R″ in turn is straight-chain or branched C1-C30-alkyl or C5-C24-aryl, or by C5-C24-aryl or -heteroaryl radicals, which are in turn either unsubstituted or mono- or polysubstituted by all the aforementioned substituents.
The halogen radicals in the R′ radicals of the phosphines or diphosphines of the general formulae (1-a) and (1-b) are the same or different and are each fluorine, chlorine or bromine.
Particularly preferred phosphines of the general formula (1-a) are trialkyl-, tricycloalkyl-, triaryl-, trialkaryl-, triaralkyl-, diarylmonoalkyl-, diarylmonocycloalkyl-, dialkylmonoaryl-, dialkylmonocycloalkyl- or dicycloalkylmonoarylphosphines, where all the aforementioned radicals in turn are either unsubstituted or mono- or polysubstituted by the aforementioned substituents.
Especially preferred phosphines are those of the general formula (1-a) in which the R′ radicals are the same or different and are each phenyl, cyclohexyl, cyclohexenyl, cyclopentyl, cyclopentadienyl, phenylsulphonate or cyclohexylsulphonate.
Most preferably, the phosphines of the general formula (1-a) present in the inventive hydrogenated nitrile rubber are PPh3, P(p-Tol)3, P(o-Tol)3, PPh(CH3)2, P(CF3)3, P(p-FC6H4)3, P(p-CF3C6H4)3, P(C6H4—SO3Na)3, P(CH2C6H4—SO3Na)3, P(iso-Pr)3, P(CHCH3(CH2CH3))3, P(cyclopentyl)3, P(cyclohexyl)3, P(neopentyl)3, P(C6H5CH2)(C6H5)2, P(NCCH2CH2)2(C6H5), P[(CH3)3C]2Cl, P[(CH3)3C]2(CH3), P(tert-Bu)2(biph), P(C6H11)2Cl, P(CH3)(OCH2CH3)2, P(CH2═CHCH2)3, P(C4H3O)3, P(CH2OH)3, P(m-CH3OC6H4)3, P(C6F5)3, P[(CH3)3Si]3, P[(CH3O)3C6H2]3, where Ph is phenyl, Tol is tolyl, biph is biphenyl, Bu is butyl and Pr is propyl. Triphenylphosphine is especially preferred.
In the diphosphines of the general formula (1-b), k is 0 or 1, preferably 1.
X in the general formula (1-b) is a straight-chain or branched alkanediyl, alkenediyl or alkynediyl group, preferably a straight-chain or branched C1-C30-alkanediyl. C2-C20-alkenediyl or C2-C20-alkynediyl group, more preferably a straight-chain or branched C1-C8-alkanediyl, C2-C6-alkenediyl or C2-C6-alkynediyl group.
C1-C8-Alkanediyl is a straight-chain or branched alkanediyl radical having 1 to 8 carbon atoms. Particular preference is given to a straight-chain or branched alkanediyl radical having 1 to 6 carbon atoms, especially having 2 to 4 carbon atoms. Preference is given to methylene, ethylene, propylene, propane-1,2-diyl, propane-2,2-diyl, butane-1,3-diyl, butane-2,4-diyl, pentane-2,4-diyl and 2-methylpentane-2,4-diyl.
C2-C6-Alkenediyl is a straight-chain or branched alkenediyl radical having 2 to 6 carbon atoms. Preference is given to a straight-chain or branched alkenediyl radical having 2 to 4, more preferably 2 to 3, carbon atoms. Preferred examples include: vinylene, allylene, prop-1-ene-1,2-diyl and but-2-ene-1,4-diyl.
C2-C6-Alkynediyl is a straight-chain or branched alkynediyl radical having 2 to 6 carbon atoms. Preference is given to a straight-chain or branched alkynediyl radical having 2 to 4, more preferably 2 to 3, carbon atoms. Preferred examples include: ethynediyl and propynediyl.
The diphosphines of the general formula (1-b) present in the inventive hydrogenated nitrile rubber are most preferably Cl2PCH2CH2PCl2, (C6H11)2PCH2P(C6H11), (CH3)2PCH2CH2P(CH3)2, (C6H5)2PCCP(C6H5)2, (C6H5)2PCH═CHP(C6H5)2, (C6F5)2P(CH2)2P(C6F5)2, (C5H5)2P(CH2)2P(C6H5)2, (C6H5)2P(CH2)3P(C6H5)2, (C6H5)2P(CH2)4P(C6H5)2, (C6H5)2P(CH2)2P(C6H5)2, (C6H5)2PCH(CH3)CH(CH3)P(C6H5)2 or (C6H5)2PCH(CH3)CH2P(C6H5)2.
Particular diphosphines likewise usable in accordance with the invention are also published in Chem. Eur. J. 2008, 14, 9491-9494. Examples include:
The phosphine oxide or diphosphine oxide component (ii) in the inventive hydrogenated nitrile rubber typically comprises oxides of the above-defined phosphines or diphosphines.
Particularly component (i) represents a phosphine, most preferably triphenylphosphine, and correspondingly component (ii) represents a phosphine oxide, most preferably triphenylphosphine oxide.
The inventive hydrogenated nitrile rubbers have repeating units of at least one α,β-unsaturated nitrile monomer and at least one conjugated diene monomer. They may additionally have repeating units of one or more further copolymerizable monomers.
The inventive hydrogenated nitrile rubber comprises fully or partly hydrogenated nitrile rubbers. The hydrogenation level may be within a range from at least 50% and up to 100%, or from 75% to 100%. Typically the inventive hydrogenated nitrile rubber has a high hydrogenation degree, customarily 80 to 100%, preferably 90 to 100%, more preferably 92 to 100%, and even more preferably 94 to 100%. Those skilled in the art refer to “fully hydrogenated types” which shall also be encompassed by the present invention, even when the residual C═C double bond content (also abbreviated to “RDB”) is not more than about 0.9%, meaning that the hydrogenation level is greater than or equal to 99.1%.
The repeating units of the at least one conjugated diene are preferably based on (C4-C6) conjugated dienes or mixtures thereof. Particular preference is given to 1,2-butadiene, 1,3-butadiene, isoprene, 2,3-dimethylbutadiene, piperylene and mixtures thereof. Especially preferred are 1,3-butadiene, isoprene and mixtures thereof. Even more preferred is 1,3-butadiene.
The α,β-unsaturated nitrile used for production of the inventive nitrile rubbers may be any known α,β-unsaturated nitrile, preference being given to (C3-C5)-α,β-unsaturated nitriles such as acrylonitrile, methacrylonitrile, ethacrylonitrile or mixtures thereof. Particular preference is given to acrylonitrile.
If one or more further copolymerizable monomers are used, these may, for example, be aromatic vinyl monomers, preferably styrene, α-methylstyrene and vinylpyridine, fluorinated vinyl monomers, preferably fluoroethyl vinyl ether, fluoropropyl vinyl ether, o-fluoromethylstyrene, vinyl pentafluorobenzoate, difluoroethylene and tetrafluoroethylene, or else copolymerizable antiageing monomers, preferably N-(4-anilinophenyl)acrylamide, N-(4-anilinophenyl)methacrylamide, N-(4-anilinophenyl)cinnamides, N-(4-anilinophenyl)crotonamide, N-phenyl-4-(3-vinylbenzyloxy)aniline and N-phenyl-4-(4-vinylbenzyloxy)aniline, and also nonconjugated dienes, such as 4-cyanocyclohexene and 4-vinylcyclohexene, or else alkynes such as 1- or 2-butyne.
In addition, the copolymerizable termonomers used may be monomers containing hydroxyl groups, preferably hydroxyalkyl (meth)acrylates. It is also possible to use correspondingly substituted (meth)acrylamines.
Examples of suitable hydroxyalkyl acrylate monomers are 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, 3-phenoxy-2-hydroxypropyl (meth)acrylate, glyceryl mono(meth)acrylate, hydroxybutyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxymethyl(meth)acrylamide, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl(meth)acrylamide, di(ethylene glycol) itaconate, di(propylene glycol) itaconate, bis(2-hydroxypropyl) itaconate, bis(2-hydroxyethyl) itaconate, bis(2-hydroxyethyl) fumarate, bis(2-hydroxyethyl) maleate and hydroxymethyl vinyl ketone.
In addition, the copolymerizable termonomers used may be monomers containing epoxy groups, preferably glycidyl (meth)acrylates.
Examples of monomers containing epoxy groups are diglycidyl itaconate, glycidyl p-styrenecarboxylate, 2-ethylglycidyl acrylate, 2-ethylglycidyl methacrylate, 2-(n-propyl)glycidyl acrylate, 2-(n-propyl)glycidyl methacrylate, 2-(n-butyl)glycidyl acrylate, 2-(n-butyl)glycidyl methacrylate, glycidylmethyl methacrylate, glycidylmethyl methacrylate, glycidyl acrylate, (3′,4′-epoxyheptyl)-2-ethyl acrylate, (3,4-epoxyheptyl)-2-ethyl methacrylate, 6′,7-epoxyheptyl acrylate, 6′,7′-epoxyheptyl methacrylate, allyl glycidyl ether, allyl 3,4-epoxyheptyl ether, 6,7-epoxyheptyl allyl ether, vinyl glycidyl ether, vinyl 3,4-epoxyheptyl ether, 3,4-epoxyheptyl vinyl ether, 6,7-epoxyheptyl vinyl ether, o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl ether, p-vinylbenzyl glycidyl ether and 3-vinylcyclohexene oxide.
Alternatively, further copolymerizable monomers used may be copolymerizable termonomers containing carboxyl groups, for example α,β-unsaturated monocarboxylic acids, esters thereof, α,β-unsaturated dicarboxylic acids, mono- or diesters thereof or the corresponding anhydrides or amides thereof.
The α,β-unsaturated monocarboxylic acids used may preferably be acrylic acid and methacrylic acid.
It is also possible to use esters of the α,β-unsaturated monocarboxylic acids, preferably the alkyl esters and alkoxyalkyl esters thereof. Preference is given to the alkyl esters, especially C1-C18 alkyl esters, of the α,β-unsaturated monocarboxylic acids, particular preference to alkyl esters, especially C1-C18-alkyl esters of acrylic acid or of methacrylic acid, especially methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, n-dodecyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate and 2-ethylhexyl methacrylate. Preference is also given to alkoxyalkyl esters of the α,β-unsaturated monocarboxylic acids, particular preference to alkoxyalkyl esters of acrylic acid or of methacrylic acid, especially C2-C12-alkoxyalkyl esters of acrylic acid or of methacrylic acid, even more preferably methoxymethyl acrylate, ethoxyethyl (meth)acrylate and methoxyethyl (meth)acrylate. It is also possible to use mixtures of alkyl esters, for example those mentioned above, with alkoxyalkyl esters, for example in the form of those mentioned above. It is also possible to use cyanoalkyl acrylate and cyanoalkyl methacrylates in which the number of carbon atoms in the cyanoalkyl group is 2-12, preferably α-cyanoethyl acrylate, β-cyanoethyl acrylate and cyanobutyl methacrylate. It is also possible to use hydroxyalkyl acrylates and hydroxyalkyl methacrylate in which the number of carbon atoms of the hydroxyalkyl groups is 1-12, preferably 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and 3-hydroxypropyl acrylate; it is also possible to use acrylates or methacrylates containing fluorine-substituted benzyl groups, preferably fluorobenzyl acrylate and fluorobenzyl methacrylate. It is also possible to use acrylates and methacrylates containing fluoroalkyl groups, preferably trifluoroethyl acrylate and tetrafluoropropyl methacrylate. It is also possible to use α,β-unsaturated carboxylic esters containing amino groups, such as dimethylaminomethyl acrylate and diethylaminoethyl acrylate. Further monomers used may be α,β-unsaturated dicarboxylic acids, preferably maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid and mesaconic acid.
It is additionally possible to use α,β-unsaturated dicarboxylic anhydrides, preferably maleic anhydride, itaconic anhydride, citraconic anhydride and mesaconic anhydride.
It is additionally possible to use mono- or diesters of α,β-unsaturated dicarboxylic acids.
These α,β-unsaturated dicarboxylic mono- or diesters may, for example, be alkyl, preferably C1-C10-alkyl, especially ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl or n-hexyl, alkoxyalkyl, preferably C2-C12-alkoxyalkyl, more preferably C3-C8-alkoxyalkyl, hydroxyalkyl, preferably C1-C12-hydroxyalkyl, more preferably C2-C8-hydroxyalkyl, cycloalkyl, preferably C5-C12-cycloalkyl, more preferably C6-C12-cycloalkyl, alkylycloalkyl, preferably C6-C12-alkylcycloalkyl, more preferably C7-C10-alkylcycloalkyl, aryl, preferably C6-C14-aryl, mono- or diesters, where any diesters may also be mixed esters.
Particularly preferred alkyl esters of α,β-unsaturated monocarboxylic acids are methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethythexyl (meth)acrylate, octyl (meth)acrylate, 2-propylheptyl acrylate and lauryl (meth)acrylate. In particular, n-butyl acrylate is used.
Particularly preferred alkoxyalkyl esters of the α,β-unsaturated monocarboxylic acids are methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate and methoxyethyl (meth)acrylate. In particular, methoxyethyl acrylate is used.
Other esters of the α,β-unsaturated monocarboxylic acids used are additionally, for example, polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, N-(2-hydroxyethyl)acrylamide, N-(2-hydroxymethyl)acrylamide and urethane (meth)acrylate.
Examples of α,β-unsaturated dicarboxylkc monoesters include
The α,β-unsaturated dicarboxylic diesters used may be the analogous diesters based on the aforementioned monoester groups, where the ester groups may also be chemically different groups.
Useful further copolymerizable monomers are also free-radically polymerizable compounds containing at least two olefinic double bonds per molecule. Examples of polyunsaturated compounds are acrylates, methacrylates or itaconates of polyols, for example ethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, butanediol 1,4-diacrylate, propane-1,2-diol diacrylate, butane-1,3-diol dimethacrylate, neopentyl glycol diacrylate, trimethylolpropane di(meth)acrylate, trimethylolethane di(meth)acrylate, glyceryl di- and triacrylate, pentaerythrityl di-, tri- and tetraacrylate or -methacrylate, dipentaerythrityl tetra-, penta- and hexaacrylate or -methacrylate or -itaconate, sorbityl tetraacrylate, sorbityl hexamethacrylate, diacrylates or dimethacrylates of 1,4-cyclohexanediol, 1,4-dimethylokcyclohexane, 2,2-bis(4-hydroxyphenyl)propane, of polyethylene glycols or of oligoesters or oligourethanes with terminal hydroxyl groups. The polyunsaturated monomers used may also be acrylamides, for example methylenebisacrylamide, hexamethylene-1,6-bisacrylamide, diethylenetriaminetrismethacrylamide, bis(methacrylamidopropoxy)ethane or 2-acrylamidoethyl acrylate. Examples of polyunsaturated vinyl and allyl compounds are divinylbenzene, ethylene glycol divinyl ether, diallyl phthalate, allyl methacrylate, diallyl maleate, triallyl isocyanurate or triallyl phosphate.
The proportions of conjugated diene and α,β-unsaturated nitrile in the inventive hydrogenated nitrile rubbers to be used or the inventive hydrogenated nitrile rubbers may vary within wide ranges. The proportion of, or of the sum total of, the conjugated diene(s) is typically in the range from 20 to 95% by weight, preferably in the range from 45 to 90% by weight, more preferably in the range from 50 to 85% by weight, based on the overall polymer. The proportion of, or of the sum total of, the α,β-unsaturated nitrile(s) is typically in the range from 5 to 80% by weight, preferably 10 to 55% by weight, more preferably 15 to 50% by weight, based on the overall polymer. The proportions of the repeating units of conjugated diene and α,β-unsaturated nitrile in the inventive hydrogenated nitrile rubbers to be used or the inventive hydrogenated nitrile rubbers add up to 100% by weight in each case.
The additional monomers may be present in amounts of 0 to 40% by weight, preferably 0 to 30% by weight, more preferably 0 to 26% by weight, based on the overall polymer. In this case, corresponding proportions of the repeating units of the conjugated diene(s) and/or of the repeating units of the α,β-unsaturated nitrile(s) are replaced by the proportions of these additional monomers, where the proportions of all the repeating units of the monomers must also add up to 100% by weight in each case.
If esters of (meth)acrylic acid are used as additional monomers, this is typically done in amounts of 1 to 25% by weight. If α,β-unsaturated mono- or dicarboxylic acids are used as additional monomers, this is typically done in amounts of less than 10% by weight.
Preference is given to hydrogenated inventive nitrile rubbers having repeating units derived from acrylonitrile and 1,3-butadiene. Preference is further given to inventive hydrogenated nitrile rubbers having repeating units of acrylonitrile, 1,3-butadiene and one or more further copolymerizable monomers. Preference is likewise given to hydrogenated nitrile rubbers having repeating units of acrylonitrile, 1,3-butadiene and one or more α,β-unsaturated mono- or dicarboxylic acids or esters or amides thereof, and especially repeating units of an alkyl ester of an α,β-unsaturated carboxylic acid, most preferably of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate or lauryl (meth)acrylate.
In a preferred embodiment, the inventive hydrogenated nitrile rubbers are essentially filler-free. “Essentially filler-free” in the context of this application means that the inventive hydrogenated nitrile rubbers contains less than 5% by weight of fillers, based on 100% by weight of hydrogenated nitrile rubber.
In a particularly preferred embodiment, the inventive hydrogenated nitrile rubbers contain, based on 100% by weight of hydrogenated nitrile rubber, less than 5% by weight of carbon black, silica, barium sulphate, titanium dioxide, zinc oxide, calcium oxide, calcium carbonate, magnesium oxide, aluminium oxide, iron oxide, aluminium hydroxide, magnesium hydroxide, aluminium silicates, diatomaceous earth, talc, kaolins, bentonites, carbon nanotubes, Teflon (the latter preferably in powder form) and/or silicates.
The nitrogen content is determined in the inventive hydrogenated nitrile rubbers to DIN 53 625 according to Kjeldahl. Due to the content of polar comonomers, the nitrile rubbers are typically≧85% by weight soluble in methyl ethyl ketone at 20° C.
The glass transition temperatures of the inventive hydrogenated nitrile rubbers are within the range of −70° C. to +10° C., preferably within the range of −60° C. to 0° C.
The hydrogenated nitrile rubbers have Mooney viscosities ML 1+4 at 100° C. of 10 to 150 Mooney units (MU), preferably of 20 to 100 MU.
The Mooney viscosity of the hydrogenated nitrile rubbers is determined in a shearing disc viscometer to DIN 53523/3 or ASTM D 1646 at 100° C.
In an alternative embodiment the inventive hydrogenated nitrile rubber has
In said alternative embodiment the hydrogenation degree of the hydrogenated nitrile rubber is in the range from 80 to 100%, preferably from 90 to 100%, more preferably from 92 to 100%, even more preferably from 94 to 100%.
The inventive hydrogenated nitrile rubbers having
This analogously applies to the preparation of the alternative inventive hydrogenated nitrile rubbers which differ from the ones described in the preceding paragraph only in that (i) the content of phosphines, diphosphines or mixtures thereof is in the range from greater than 0 to 1% by weight, preferably from 0.1% by weight to 0.9% by weight, and more preferably from 0.15 to 0.85% by weight, based on the hydrogenated nitrile rubber.
The inventive reaction of the phosphine- or diphosphine-containing hydrogenated nitrile rubber with at least one of the oxidizing agents can be conducted in various variants.
The following method has been found to be useful:
It has typically been found to be useful to produce the hydrogenated nitrile rubber having a content of phosphines or diphosphines in the range of amounts of 0.25-5% by weight, preferably 0.3 to 4.5% by weight, more preferably from 0.4 to 4.25% by weight and especially of 0.5-4% by weight, based on the hydrogenated nitrile rubber, in a first step by hydrogenation.
In the catalytic hydrogenation reaction of the process according to the invention, at least one phosphine or diphosphine is present:
In a first embodiment, this phosphine or diphosphine is present as a ligand in the hydrogenation catalyst used. No separate addition of a phosphine or diphosphine is required.
In a second embodiment, a phosphine or diphosphine is added as what is called a cocatalyst alongside the phosphine or diphosphine ligand-containing hydrogenation catalyst in the hydrogenation reaction.
In a third embodiment, any desired hydrogenation catalyst that does not contain any phosphine or diphosphine can be used, and the phosphine or diphosphine is added as a cocatalyst.
In a preferred embodiment, the hydrogenation is performed using at least one catalyst having at least one phosphine or diphosphine ligand.
Preference is additionally given to hydrogenation using at least one catalyst having at least one phosphine or diphosphine ligand, and additionally in the presence of at least one phosphine or diphosphine as a cocatalyst.
In all embodiments, the hydrogenation catalysts are typically based on the noble metals rhodium, ruthenium, osmium, palladium, platinum or iridium, preference being given to rhodium, ruthenium and osmium. The catalysts specified hereinafter are usable in all the embodiments.
It is possible to use rhodium complex catalysts of the general formula (A)
Rh(X)n(L)m (A)
In the general formula (A), X are the same or different and are preferably hydrogen or chlorine.
L in the general formula (A) is preferably a phosphine or diphosphine corresponding to the general formulae (1-a) and (1-b) shown above, including the general, preferred and particularly preferred definitions given there.
Particularly preferred catalysts of the general formula (A) are tris(triphenylphosphine)rhodium(I) chloride, tris(triphenylphosphine)rhodium(III) chloride, tris(dimethyl sulphoxide)rhodium(III) chloride, hydridorhodiumtetrakis(triphenylphosphine) and the corresponding compounds in which triphenylphosphine has been replaced wholly or partly by tricyclohexylphosphine.
It is also possible to use ruthenium complex catalysts. These are described, for example, in DE-A 39 21 264 and EP-A-0 298 386. They typically have the general formula (B)
RuXn[(L1)m(L2)5-2] (B)
Examples of L1 ligands in the general formula (B) of the cyclopentadienyl ligand type of the general formula (2) include cyclopentadienyl, pentamethylcyclopentadienyl, ethyltetramethylcyclopentadienyl, pentaphenylcyclopentadienyl, dimethyltriphenylcyclopentadienyl, indenyl and fluorenyl. The benzene rings in the L1 ligands of the indenyl and fluorenyl type may be substituted by C1-C6-alkyl radicals, especially methyl, ethyl and isopropyl, C1-C4-alkoxy radicals, especially methoxy and ethoxy, aryl radicals, especially phenyl, and halogens, especially fluorine and chlorine. Preferred L1 ligands of the cyclopentadienyl type are the respectively unsubstituted cyclopentadienyl, indenyl and fluorenyl radicals.
In the L1 ligand in the general formula (B) of the (R6—COO) type, R6 includes, for example, straight-chain or branched, saturated hydrocarbyl radicals having 1 to 20, preferably 1 to 12 and especially 1 to 6 carbon atoms, cyclic saturated hydrocarbyl radicals having 5 to 12 and preferably 5 to 7 carbon atoms, and also aromatic hydrocarbyl radicals having 6 to 18 and preferably 6 to 10 carbon atoms, or aryl-substituted alkyl radicals having preferably a straight-chain or branched C1-C6 alkyl radical and a C6-C18 aryl radical, preferably phenyl.
The above-elucidated R6 radicals in (R6—COO) in the ligand L1 of the general formula (B) may optionally be substituted by hydroxyl, C1-C6-alkoxy, C1-C6-carbalkoxy, fluorine, chlorine or di-C1-C4-alkylamino, the cycloalkyl, aryl and aralkyl radicals additionally by C1-C6-alkyl; alkyl, cycloalkyl and aralkyl groups may contain keto groups. Examples of the R6 radical are methyl, ethyl, propyl, isopropyl, tert-butyl, cyclohexyl, phenyl, benzyl and trifluoromethyl. Preferred R6 radicals are methyl, ethyl and ten-butyl.
The L2 ligand in the general formula (B) is preferably a phosphine or diphosphine according to the general formulae (1-a) and (1-b) shown above, including the general, preferred and particularly preferred definitions given there, or is an arsine of the general formula (3)
Preferred ligands L2 of the general formula (3) are triphenylarsine, ditolylphenylarsine, tris(4-ethoxyphenyl)arsine, diphenylcyclohexylarsine, dibutylphenylarsine and diethylphenylarsine.
Preferred ruthenium catalysts of the general formula (B) are selected from the group which follows, where “Cp” represents cyclopentadienyl, i.e. C5H5−, “Ph” represents phenyl, “Cy” represents cyclohexyl and “dppe” represents 1,2-bis(diphenylphosphino)ethane: RuCl2, (PPh3)3; RuHCl(PPh3)3; RuH2(PPh3)3; RuH2(PPh3)4; RuH4(PPh3)3; RuH(CH3COO)(PPh3)3; RuH(C2H5COO)(PPh3)3; RuH(CH3COO)2(PPh3)2; RuH(NO)2(PPh3)2; Ru(NO)2(PPh3)2; RuCl(Cp)(PPh3)2; RuH(Cp)(PPh3)2; Ru(SnCl3)(Cp)(PPh3)2; RuCl(μ5-C9H7)(PPh3)2; RuH(μ5-C9H7)(PPh3)2; Ru(SnCl3)(μ5-C9H7)(PPh3)2; RuCl(μ5-C13H9)(PPh3)2; RuH(μ5-C13H9)(PPh3)2; Ru(SnCl3)(μ5-C13H9)(PPh3)2; RuCl(μ5-C9H7)(dppe); RuHCl(CO)(PCy3); RuH(NO)(CO)(PCy3)3; RuHCl(CO)2(PPh3)2; RuCl2(CO)(dppe) RuHCl(CO)(PCy3), RuHCl(CO)(dppe)2, RuH(CH3COO)(PPh3)3; RuH(CH3COO)2(PPh3)2; and RuH(CH3COO)(PPh)3.
Suitable catalysts are also those of the general formula (C)
In one embodiment of the catalysts of the general formula (C), one R radical is hydrogen and the other R radical is C1-C20-alkyl, C3-C10-cycloalkyl, C2-C20-alkenyl, C2-C20-alkynyl, C6-C24-aryl, C1-C20-carboxylate, C1-C20-alkoxy, C2-C20-alkenyloxy, C2-C20-alkynyloxy, C6-C24-aryloxy, C2-C20-alkoxycarbonyl, C1-C30-alkylamino, C1-C30-alkylthio, C6-C24-arylthio, C1-C20-alkylsulphonyl or C1-C20-alkylsulphinyl, where all these radicals may each be substituted by one or more alkyl, halogen, alkoxy, aryl or heteroaryl radicals.
In the catalysts of the general formula (C), X1 and X2 are the same or different and are two ligands, preferably anionic ligands.
X1 and X2 may, for example, be hydrogen, halogen, pseudohalogen, straight-chain or branched C1-C30-alkyl, C6-C24-aryl, C1-C20-alkoxy, C6-C24-aryloxy, C3-C20-alkyldiketonate, C6-C24-aryldiketonate, C1-C20-carboxylate, C1-C20-alkylsulphonate, C6-C24-arylsulphonate, C1-C20-alkylthiol, C6-C24-arylthiol, C1-C20-alkylsulphonyl, C1-C20-alkylsulphinyl, mono- or dialkylamide, mono- or dialkylcarbamate, mono- or dialkylthiocarbamate, mono- or dialkyldithiocarbamate or mono- or dialkylsulphonamide radicals.
The aforementioned X1 and X2 radicals may also be substituted by one or more further radicals, for example by halogen, preferably fluorine, C1-C10-alkyl, C1-C10-alkoxy or C6-C24-aryl, where these radicals too may optionally in turn be substituted by one or more substituents selected from the group comprising halogen, preferably fluorine, C1-C5-alkyl, C1-C5-alkoxy and phenyl.
In a further embodiment, X1 and X2 are the same or different and are each halogen, especially fluorine, chlorine, bromine or iodine, benzoate, C1-C5-carboxylate. C1-C5-alkyl, phenoxy, C1-C5-alkoxy, C1-C5-alkylthiol, C6-C24-arylthiol, C6-C24-aryl or C1-C5-alkylsulphonate.
In a further embodiment, X1 and X2 are identical and are each halogen, especially chlorine, CF3COO, CH3COO, CFH2COO, (CH3)3CO, (CF3)2(CH3)CO, (CF3)(CH3)2CO, PhO (phenoxy), MeO (methoxy), EtO (ethoxy), tosylate (p-CH3—C6H4—SO3), mesylate (CH3SO3) or CF3SO3 (trifluoromethanesulphonate).
In the general formula (C), L are identical or different ligands and are preferably uncharged electron donors.
The two L ligands may, for example, each independently be a phosphine, sulphonated phosphine, phosphate, phosphinite, phosphonite, arsine, stibine, ether, amine, amide, sulphoxide, carboxyl, nitrosyl, pyridine, thioether, an imidazoline or an imidazolidine ligand.
Preferably, the two L ligands are each independently a C6-C24-aryl-, C1-C10-alkyl- or C3-C20-cycloalkylphosphine ligand, a sulphonated C6-C24-aryl- or sulphonated C1-C10-alkylphosphine ligand, a C6-C24-aryl- or C1-C10-alkylphosphinite ligand, a C6-C24-aryl- or C1-C10-alkylphosphonite ligand, a C6-C24-aryl- or C1-C10-alkylphosphite ligand, a C6-C24-aryl- or C1-C10-alkylarsine ligand, a C6-C24-aryl- or C1-C10-alkylamine ligand, a pyridine ligand, a C6-C24-aryl or C1-C10-alkyl sulphoxide ligand, a C6-C24-aryl or C1-C10-alkyl ether ligand or a C6-C24-aryl- or C1-C10-alkylamide ligand, all of which may each be substituted by a phenyl group which is in turn either unsubstituted or substituted by one or more halogen. C1-C5-alkyl or C1-C5-alkoxy radical(s).
The term “phosphine” includes, for example, PPh3, P(p-Tol)3, P(o-Tol)3, PPh(CH)2, P(CF3)3, P(p-FC6H4)3, P(p-CF3C6H4)3, P(C6H4—SO3Na)3, P(CH2C6H4—SO3Na)3, P(isopropyl)3, P(CHCH3(CH2CH3))3. P(cyclopentyl)3, P(cyclohexyl)3, P(neopentyl)3 and P(neophenyl)3, where “Ph” represents phenyl and “Tol” represents tolyl.
The term “phosphinite” includes, for example, triphenylphosphinite, tricyclohexylphosphinite, triisopropylphosphinite and methyldiphenylphosphinite.
The term “phosphite” includes, for example, triphenylphosphite, tricyclohexylphosphite, tri-tert-butylphosphite, triisopropylphosphite and methyldiphenylphosphite.
The term “stibine” includes triphenylstibine, tricyclohexylstibine and trimethylstibine.
The term “sulphonate” includes, for example, trifluoromethanesulphonate, tosylate and mesylate.
The term “sulphoxide” includes, for example, (CH3)2S(═O) and (C6H5)2S═O.
The term “thioether” includes, for example, CH3SCH3, C6H5SCH3, CH3OCH2CH2SCH3 and tetrahydrothiophene.
The term “pyridine” shall be understood in the context of this application as an umbrella term for all pyridine-based ligands, as specified, for example, by Grubbs in WO-A-03/011455. These include pyridine, and pyridine having mono- or polysubstitution in the form of the picolines (α-, β-, and γ-picoline), lutidines (2,3-, 2,4-, 2,5-, 2,6-, 3,4- and 3,5-lutidine), collidine (2,4,6-trimethylpyridine), trifluoromethylpyridine, phenylpyridine, 4-(dimethylamino)pyridine, chloropyridines, bromopyridines, nitropyridines, quinoline, pyrimidine, pyrrole, imidazole and phenylimidazole.
If one or both of the L ligands in formula (C) is an imidazoline and/or imidazolidine radical (also referred to collectively hereinafter as “Im” ligand(s)), the latter typically has a structure of the general formula (4a) or (4b)
Optionally, one or more of the R8, R9, R10, R11 radicals may each independently be substituted by one or more substituents, preferably straight-chain or branched C1-C10-alkyl, C3-C8-cycloalkyl, C1-C10-alkoxy or C6-C24-aryl, where these aforementioned substituents may in turn be substituted by one or more radicals, preferably selected from the group of halogen, especially fluorine, chlorine or bromine, C1-C5-alkyl, C1-C5-alkoxy and phenyl.
Merely for clarification, it should be added that the structures shown in the general formulae (4a) and (4b) in the context of this application are equivalent to the structures (4a) and (4b) frequently also encountered in the literature for this radical, which emphasize the carbene character of the radical. This also applies analogously to the corresponding preferred structures (5a)-(5f) shown below. These radicals are all referred to collectively hereinafter as “Im” radical.
In a preferred embodiment of the catalysts of the general formula (C), R8 and R9 are each independently hydrogen, C6-C24-aryl, more preferably phenyl, straight-chain or branched C1-C10-alkyl, more preferably propyl or butyl, or form, together with the carbon atoms to which they are bonded, a cycloalkyl or aryl radical, where all the aforementioned radicals may optionally be substituted in turn by one or more further radicals selected from the group comprising straight-chain or branched C1-C10-alkyl, C1-C10-alkoxy, C6-C24-aryl and a functional group selected from the group of hydroxyl, thiol, thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulphide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate and halogen.
In a preferred embodiment of the catalysts of the general formula (C), the R10 and R11 radicals are additionally the same or different and are each straight-chain or branched C1-C10-alkyl, more preferably methyl, isopropyl or neopentyl, C3-C10-cycloalkyl, preferably adamantyl, C6-C24-aryl, more preferably phenyl, C1-C10-alkylsulphonate, more preferably methanesulphonate, C6-C10-arylsulphonate, more preferably p-toluenesulphonate.
Optionally, the aforementioned radicals as definitions of R10 and R11 are substituted by one or more further radicals selected from the group comprising straight-chain or branched C1-C5-alkyl, especially methyl, C1-C5-alkoxy, aryl and a functional group selected from hydroxyl, thiol, thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulphide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate and halogen, especially fluorine, chlorine and bromine.
More particularly, the R10 and R11 radicals may be the same or different and are each isopropyl, neopentyl, adamantyl, mesityl (2,4,6-trimethylphenyl), 2,6-difluorophenyl, 2,4,6-trifluorophenyl or 2,6-diisopropylphenyl.
Particularly preferred Im radicals have the structures (5a) to (5f) below, where Ph in each case is a phenyl radical, Bu is a butyl radical and Mes in each case is 2,4,6-trimethylphenyl radical, or Mes alternatively in all cases is 2,6-diisopropylphenyl.
A wide variety of different representatives of the catalysts of the formula (C) is known in principle, for example from WO-A-96/04289 and WO-A-97/06185.
As an alternative to the preferred Im radicals, one or both L ligands in the general formula (C) are preferably also identical or different trialkylphosphine ligands in which at least one of the alkyl groups is a secondary alkyl group or a cycloalkyl group, preferably isopropyl, isobutyl, sec-butyl, neopentyl, cyclopentyl or cyclohexyl.
More preferably, in the general formula (C), one or both L ligands are a trialkylphosphine ligand in which at least one of the alkyl groups is a secondary alkyl group or a cycloalkyl group, preferably isopropyl, isobutyl, sec-butyl, neopentyl, cyclopentyl or cyclohexyl.
Particular preference is given to catalysts which are covered by the formula (C) and have the structures (6) (Grubbs (I) catalyst) and (7) (Grubbs (II) catalyst), where Cy is cyclohexyl.
Suitable catalysts are also preferably those of the general formula (C1)
Preferred catalysts of the general formula (C1) which can be used are, for example, those of the formulae (8a) and (8b), where each Mes is 2,4,6-trimethylphenyl and Ph is phenyl.
These catalysts are known, for example, from WO-A-2004/112951. Catalyst (8a) is also referred to as the Nolan catalyst.
Suitable catalysts are also preferably those of the general formula (D)
The catalysts of the general formula (D) are known in principle and are described, for example, by Hoveyda et al. in US 2002/0107138 A1 and Angew. Chem. Int. Ed. 2003, 42, 4592, and by Grela in WO-A-2004/035596, Eur. J. Org. Chem 2003, 963-966 and Angew. Chem. Int. Ed. 2002, 41, 4038, and also in J. Org. Chem. 2004, 69, 6894-96 and Chem. Eur. J 2004, 10, 777-784, and also in US 2007/043180. The catalysts are commercially available or can be prepared according to the references cited.
In the catalysts of the general formula (D), L is a ligand which typically has an electron donor function and may assume the same general, preferred and particularly preferred definitions as L in the general formula (C). In addition, L in the general formula (D) is preferably a P(R7)3 radical where R7 are independently C1-C6 alkyl, C3-C8-cycloalkyl or aryl, or else an optionally substituted imidazoline or imidazolidine radical (“Im”).
C1-C6-Alkyl is, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, neopentyl, l-ethylpropyl and n-hexyl.
C3-C8-Cycloalkyl comprises cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl.
Aryl comprises an aromatic radical having 6 to 24 skeleton carbon atoms, preferably mono-, bi- or tricyclic carbocyclic aromatic radicals having 6 to 10 skeleton carbon atoms, especially phenyl, biphenyl, naphthyl, phenanthrenyl or anthracenyl.
The imidazoline or imidazolidine radical (Im) has the same general, preferred and particularly preferred structures as the catalysts of the general formula (C).
Particularly suitable catalysts of the general formula (D) are those in which the R10 and R11 radicals are the same or different and are each straight-chain or branched C1-C10-alkyl, more preferably isopropyl or neopentyl, C3-C10-cycloalkyl, preferably adamantyl, C6-C24-aryl, more preferably phenyl, C1-C10-alkylsulphonate, more preferably methanesulphonate, or C6-C10-arylsulphonate, more preferably p-toluenesulphonate.
Optionally, the aforementioned radicals as definitions of R10 and R11 are substituted by one or more further radicals selected from the group comprising straight-chain or branched C1-C10-alkyl, especially methyl, C1-C5-alkoxy, aryl and a functional group selected from the group of hydroxyl, thiol, thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulphide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate and halogen.
More particularly, the R10 and R11 radicals may be the same or different and are each isopropyl, neopentyl, adamantyl or mesityl.
Particularly preferred imidazoline or imidazolidine radicals (Im) have the structures (5a-5f) already specified above, where Mes in each case is 2,4,6-trimethylphenyl.
In the catalysts of the general formula (D), X1 and X2 have the same general, preferred and particularly preferred definitions as the catalysts of the general formula (C).
In the general formula (D), the R1 radical is an alkyl, cycloalkyl, alkenyl, alkynyl, aryl, alkoxy, alkenyloxy, alkynyloxy, aryloxy, alkoxycarbonyl, alkylamino, alkylthio, arylthio, alkylsulphonyl or alkylsulphinyl radical, all of which may each optionally be substituted by one or more alkyl, halogen, alkoxy, aryl or heteroaryl radicals.
Typically, the R1 radical is a C1-C30-alkyl, C3-C20-cycloalkyl, C2-C20-alkenyl, C2-C20-alkynyl, C6-C24-aryl, C1-C20-alkoxy, C2-C20-alkenyloxy, C2-C20-alkynyloxy, C6-C24-aryloxy, C1-C20-alkoxycarbonyl, C1-C20-alkylamino, C1-C20-alkylthio, C6-C24-arylthio, C1-C20-alkylsulphonyl or C1-C20-alkylsulphinyl radical, all of which may each optionally be substituted by one or more alkyl, halogen, alkoxy, aryl or heteroaryl radicals.
Preferably, R1 is a C3-C20-cycloalkyl radical, a C6-C24-aryl radical or a straight-chain or branched C1-C30-alkyl radical, where the latter may optionally be interrupted by one or more double or triple bonds or else one or more heteroatoms, preferably oxygen or nitrogen. More preferably, R1 is a straight-chain or branched C1-C12-alkyl radical.
The C3-C20-cycloalkyl radical comprises, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl.
The C1-C12-alkyl radical may, for example, be methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, neopentyl, 1-ethylpropyl, n-hexyl, n-heptyl, n-octyl, n-decyl or n-dodecyl. More particularly, R1 is methyl or isopropyl.
The C6-C24-aryl radical is an aromatic radical having 6 to 24 skeleton carbon atoms. Preferred mono-, bi- or tricyclic carbocyclic aromatic radicals having 6 to 10 skeleton carbon atoms include, for example, phenyl, biphenyl, naphthyl, phenanthrenyl or anthracenyl.
In the general formula (D), the R2, R3, R4 and R5 radicals are the same or different and may each be hydrogen or organic or inorganic radicals.
In a suitable embodiment, R2, R3, R4, R5 are the same or different and are each hydrogen, halogen, nitro, CF3, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, alkoxy, alkenyloxy, alkynyloxy, aryloxy, alkoxycarbonyl, alkylamino, alkylthio, arylthio, alkylsulphonyl or alkylsulphinyl radicals, all of which may each optionally be substituted by one or more alkyl, alkoxy, halogen, aryl or heteroaryl radicals.
Typically, R2, R3, R4, R5 are the same or different and are each hydrogen, halogen, preferably chlorine or bromine, nitro, CF3, C1-C30-alkyl, C3-C20-cycloalkyl, C2-C20-alkenyl, C2-C20-alkynyl, C6-C24-aryl, C1-C20-alkoxy. C2-C20-alkenyloxy, C2-C20-alkynyloxy, C6-C24-aryloxy, C2-C20-alkoxycarbonyl, C1-C20-alkylamino, C1-C20D-alkylthio, C6-C24-arylthio, C1-C20-alkylsulphonyl or C1-C20-alkylsulphinyl radicals, all of which may each optionally be substituted by one or more C1-C30-alkyl, C1-C20-alkoxy, halogen, C6-C24-aryl or heteroaryl radicals.
In a particularly proven embodiment, R2, R3, R4, R5 are the same or different and are each nitro, straight-chain or branched C1-C30-alkyl, C5-C20-cycloalkyl, straight-chain or branched C1-C20-alkoxy radicals or C6-C24-aryl radicals, preferably phenyl or naphthyl. The C1-C30-alkyl radicals and C1-C20-alkoxy radicals may optionally be interrupted by one or more double or triple bonds or else one or more heteroatoms, preferably oxygen or nitrogen.
In addition, two or more of the R2, R3, R4 or R5 radicals may also be bridged via aliphatic or aromatic structures. R3 and R4 may, for example, including the carbon atoms to which they are bonded in the phenyl ring of the formula (D), form a fused-on phenyl ring so as to result overall in a naphthyl structure.
In the general formula (D), the R6 radical is hydrogen or an alkyl, alkenyl, alkynyl or aryl radical. Preferably, R6 is hydrogen or a C1-C30-alkyl, a C2-C20-alkenyl, a C2-C20-alkynyl or a C6-C24-aryl radical. More preferably, R6 is hydrogen.
Other suitable catalysts are catalysts of the general formula (D1)
in which M, L, X1, X2, R1, R2, R3, R4 and R5 may each have the general, preferred and particularly preferred definitions given for the general formula (D).
The catalysts of the general formula (D1) are known in principle, for example, from US 2002/0107138 A1 (Hoveyda et al.) and can be obtained by preparation processes specified therein.
Particularly suitable catalysts are those of the general formula (D1) where
Especially suitable catalysts are those of the general formula (D1) where
A very particularly suitable catalyst is one which is covered by the general structural formula (D1) and has the formula (9), where each Mes is 2,4,6-trimethylphenyl.
This catalyst (9) is also referred to in the literature as “Hoveyda catalyst”.
Further suitable catalysts are those which are covered by the general structural formula (D1) and have one of the following formulae; (10), (11), (12), (13), (14), (15), (16) and (17), where each Mes is 2,4,6-trimethylphenyl.
A further suitable catalyst is a catalyst of the general formula (D2)
The catalysts of the general formula (D2) are known in principle, for example, from WO-A-2004/035596 (Grela) and can be obtained by preparation processes specified therein.
Particularly suitable catalysts are those of the general formula (D2) in which
Especially suitable catalysts are those of the general formula (D2) in which
Particularly suitable catalysts are those of the structures (18) (“Grela catalyst”) and (19) below, where each Mes is 2,4,6-trimethylphenyl.
Another suitable catalyst is a dendritic catalyst of the general formula (D3)
in which X1, X2, X3 and X4 each have a structure of the general formula (20) bonded to the silicon of the formula (D3) via the methylene group shown on the right and
The catalysts of the general formula (D3) are known from US 2002/0107138 A1 and can be prepared according to the details given therein.
Another suitable catalyst is a catalyst of the formula (D4)
in which the symbol represents a support.
The support is preferably a poly(styrene-divinylbenzene) copolymer (PS-DVB).
The catalysts according to formula (D4) are known in principle from Chem. Eur. J. 2004 10, 777-784 and are obtainable by preparation methods described therein.
All the aforementioned catalysts of the (D), (D1), (D2), (D3) and (D4) types can either be used as such in the hydrogenation reaction or else they can be applied to a solid support and immobilized. Suitable solid phases or supports are those materials which are firstly inert with respect to the metathesis reaction mixture and secondly do not impair the activity of the catalyst. The catalyst can be immobilized using, for example, metals, glass, polymers, ceramic, organic polymer beads or else inorganic sol-gels, carbon black, silica, silicates, calcium carbonate and barium sulphate.
Other suitable catalysts are catalysts of the general formula (E)
The catalysts of the general formula (E) are known in principle (see, for example, Angew. Chem. Int. Ed. 2004, 43, 6161-6165).
X1 and X2 in the general formula (E) may have the same general, preferred and particularly preferred definitions as in the formulae (C) and (D).
The Im radical typically has a structure of the general formula (4a) or (4b) which has already been specified for the catalyst type of the formulae (C) and (D) and may also have any of the structures specified there as preferred, especially those of the formulae (5a)-(5f).
The R″ radicals in the general formula (E) are the same or different and are each a straight-chain or branched C1-C30-alkyl, C5-C30-cycloalkyl or aryl radical, where the C1-C30-alkyl radicals may optionally be interrupted by one or more double or triple bonds or else one or more heteroatoms, preferably oxygen or nitrogen.
Aryl comprises an aromatic radical having 6 to 24 skeleton carbon atoms. Preferred mono-, bi- or tricyclic carbocyclic aromatic radicals having 6 to 10 skeleton carbon atoms include, for example, phenyl, biphenyl, naphthyl, phenanthrenyl or anthracenyl.
The R″ radicals in the general formula (E) are preferably the same and are each phenyl, cyclohexyl, cyclopentyl, isopropyl, o-tolyl, o-xylyl or mesityl.
Other suitable catalysts are catalysts of the general formula (F)
Other suitable catalysts are catalysts of the general formula (G)
Further suitable catalysts are catalysts of the general formula (H)
Further suitable catalysts are catalysts of the general formula (K), (N) or (Q)
where
The catalysts of the general formulae (K), (N) and (Q) are known in principle, for example from WO 2003/011455 A1, WO 2003/087167 A2, Organometallics 2001, 20, 5314 and Angew. Chem. Int. Ed. 2002, 41, 4038. The catalysts are commercially available or else can be synthesized by the preparation methods specified in the aforementioned references.
In the catalysts of the general formulae (K), (N) and (Q), Z1 and Z2 are the same or different and are each uncharged electron donors. These ligands are typically weakly coordinating. They are typically optionally substituted heterocyclic groups. These may be five- or six-membered monocyclic groups having 1 to 4, preferably 1 to 3 and more preferably 1 or 2 heteroatoms or bi- or polycyclic structures composed of 2, 3, 4 or 5 of such five- or six-membered monocyclic groups, where each of the aforementioned groups may optionally be substituted by one or more alkyl, preferably C1-C10-alkyl, cycloalkyl, preferably C3-C8-cycloalkyl, alkoxy, preferably C1-C10-alkoxy, halogen, preferably chlorine or bromine, aryl, preferably C6-C24-aryl, or heteroaryl, preferably C5-C23 heteroaryl radicals, each of which may again be substituted by one or more groups, preferably selected from the group consisting of halogen, especially chlorine or bromine. C1-C5-alkyl, C1-C5-alkoxy and phenyl.
Examples of Z1 and Z2 include nitrogen-containing heterocycles such as pyridines, pyridazines, bipyridines, pyrimidines, pyrazines, pyrazolidines, pyrrolidines, piperazines, indazoles, quinolines, purines, acridines, bisimidazoles, picolylimines, imidazolidines and pyroles.
Z1 and Z2 may also be bridged to one another to form a cyclic structure. In this case, Z1 and Z2 are a single bidentate ligand.
In the catalysts of the general formulae (K), (N) and (Q). L may assume the same general, preferred and particularly preferred definitions as L in the general formulae (C) and (D).
In the catalysts of the general formulae (K), (N) and (Q), R21 and R22 and RP are the same or different and are each alkyl, preferably C1-C30-alkyl, more preferably C1-C20-alkyl, cycloalkyl, preferably C3-C20-cycloalkyl, more preferably C3-C8-cycloalkyl, alkenyl, preferably C2-C20-alkenyl, more preferably C2-C16-alkenyl, alkynyl, preferably C2-C20-alkynyl, more preferably C2-C16-alkynyl, aryl, preferably C6-C24-aryl, carboxylate, preferably C1-C30-carboxylate, alkoxy, preferably C1-C20-alkoxy, alkenyloxy, preferably C2-C20-alkenyloxy, alkynyloxy, preferably C2-C20-alkynyloxy, aryloxy, preferably C6-C24-aryloxy, alkoxycarbonyl, preferably C2-C20-alkoxycarbonyl, alkylamino, preferably C1-C30-alkylamino, alkylthio, preferably C1-C30-alkylthio, arylthio, preferably C6-C24-arylthio, alkylsulphonyl, preferably C1-C20-alkylsulphonyl, or alkylsulphinyl, preferably C1-C20-alkylsulphinyl, where the aforementioned substituents may be substituted by one or more alkyl, halogen, alkoxy, aryl or heteroaryl radicals.
In the catalysts of the general formulae (K), (N) and (Q), X1 and X2 are the same or different and may have the same general, preferred and particularly preferred definitions as specified above for X1 and X2 in the general formula (C).
Particularly suitable catalysts are those of the general formulae (K), (N) and (Q) in which
A very particularly suitable catalyst is one which is covered by the general formula (K) and has the structure (21)
The aforementioned C1-C20-alkyl, C1-C20-heteroalkyl, C1-C10-haloalkyl, C1-C10-alkoxy, C6-C24-aryl radicals, preferably phenyl, formyl, nitro, nitrogen heterocycles, preferably pyridine, piperidine and pyrazine, carboxyl, alkylcarbonyl, halocarbonyl, carbamoyl, thiocarbamoyl, carbamido, thioformyl, amino, trialkylsilyl and trialkoxysilyl, may again each be substituted by one or more halogen, preferably fluorine, chlorine or bromine, C1-C5-alkyl, C1-C5-alkoxy or phenyl radicals.
A particularly suitable catalyst is one where R23 and R24 are each hydrogen (“Grubbs III catalyst”).
Also very particularly suitable are catalysts of the structure (22a) or (22b) where R23 and R24 have the same definitions as in the formula (21), except for hydrogen.
Suitable catalysts covered by the general formulae (K), (N) and (Q) have the structural formulae (23) to (34) below, where each Mes is 2,4,6-trimethylphenyl.
Also suitable are catalysts (R) having the general structural element (R1), where the carbon atom identified by “*” is bonded to the catalyst base skeleton via one or more double bonds,
The inventive catalysts have the structural element of the general formula (R1), where the carbon atom identified by “*” is bonded to the catalyst base skeleton via one or more double bonds. When the carbon atom identified by “*” is bonded to the catalyst base skeleton via two or more double bonds, these double bonds may be cumulated or conjugated.
Catalysts (R) of this kind are described in EP-A-2 027 920. The catalysts (R) with a structural element of the general formula (R1) include, for example, those of the following general formulae (R2a) and (R2b)
In the catalysts of the general formula (R2a), the structural element of the general formula (R1) is bonded to the central metal of the complex catalyst via a double bond (n=0) or via 2, 3 or 4 cumulated double bonds (in the case that n=1, 2 or 3). In the inventive catalysts of the general formula (R2b), the structural element of the general formula (R1) is bonded to the metal of the complex catalyst via conjugated double bonds. In both cases, there is a double bond in the direction of the central metal of the complex catalyst on the carbon atom identified by “*”
The catalysts of the general formulae (R2a) and (R2b) thus include catalysts in which the following general structural elements (R3)-(R9)
are bonded via the carbon atom identified by “*”, via one or more double bonds, to the catalyst base skeleton of the general formula (R10a) or (R10b)
where X1 and X2, L1 and L2, n, n′ and R25-R39 are each as defined for the general formulae (R2a) and (R2b).
Typically, these ruthenium- or osmium-carbene catalysts are pentacoordinated.
In the structural element of the general formula (R1),
C1-C6-Alkyl in the structural element of the general formula (R1) is, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, neopentyl, 1-ethylpropyl and n-hexyl.
C3-C8-Cycloalkyl in the structural element of the general formula (R1) is, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl.
C6-C24-Aryl in the structural element of the general formula (R1) comprises an aromatic radical having 6 to 24 skeleton carbon atoms. Preferred mono-, bi- or tricyclic carbocyclic aromatic radicals having 6 to 10 skeleton carbon atoms include, for example, phenyl, biphenyl, naphthyl, phenanthrenyl or anthracenyl.
The X1 and X2 radicals in the structural element of the general formula (R1) have the same general, preferred and particularly preferred definitions which are specified for catalysts of the general formula (C).
In the general formulae (R2a) and (R2b) and analogously (R10a) and (R10b), the L1 and L2 radicals are identical or different ligands, preferably uncharged electron donors, and may have the same general, preferred and particularly preferred definitions which are specified for the catalysts of the general formula (C).
Preference is given to catalysts of the general formula (R2a) or (R2b) with a general structural unit (NI) where
Very particular preference is given to catalysts of the formula (R2a) or (R2b) with a general structural unit (R1) where
In the case that the R2 radical is bridged with another ligand of the catalyst of the formula R, for example for the catalysts of the general formulae (R2a) and (R2b), this gives rise to the following structures of the general formulae (R13a) and (R13b)
Examples of catalysts of the general formula (R) include the following structures (35) to (45):
The preparation of catalysts of the general formula (R) is known from EP-A-2 027 920.
Additionally suitable are catalysts according to the general formula (T)
These catalysts of the general formula (T) are known from US 2007/0043180.
Preference is given to catalysts of the general formula (T) in which X1 and X2 are selected from an ionic ligand in the form of halides, carboxylates and aryl oxides. More preferably, X1 and X2 are both halides, especially both chlorides. In the general formula (T), Y is preferably oxygen. R is preferably H, halogen, alkoxycarbonyl, aryloxycarbonyl, heteroaryl, carboxyl, amido, alkylsulphonyl, arylsulphonyl, alkylthio, arylthio or sulphonamido. More particularly, R is H, Cl, F or a C1-8 alkoxycarbonyl group. R1 and R2 are the same or different and are preferably each H, alkoxy, aryl, aryloxy, alkoxycarbonyl, amido, alkylthio, arylthio or a sulphonamido group. More particularly, R1 is H or an alkoxy group and R2 is hydrogen. In the general formula (T), R3 is preferably an alkyl, aryl, heteroaryl, alkylcarbonyl or arylcarbonyl group. More preferably, R3 is isopropyl, sec-butyl and methoxyethyl. In the general formula (T), EWG is preferably an aminosulphonyl, amidosulphonyl, N-heteroarylsulphonyl, arylsulphonyl, aminocarbonyl, arylsulphonyl, alkylcarbonyl, aryloxycarbonyl, halogen or haloalkyl group. More preferably, EWG is a C1-12 N-alkylaminosulphonyl, C2-12 N-heteroarylsulphonyl, C1-12 aminocarbonyl, C6-12 arylsulphonyl, C1-12alkylcarbonyl. C6-12 arylcarbonyl, C6-12 aryloxycarbonyl, Cl, F or trifluoromethyl group. In the general formula (T). L is an electron-donating ligand selected from phosphines, amino, aryl oxides, carboxylates and heterocyclic carbene radicals which may be bonded to X1 via carbon-carbon and/or carbon-heteroatom bonds.
A particularly suitable catalyst is one of the general formula (T) in which L is a heterocyclic carbene ligand or a phosphine (P(R8)29(R9) having the following structures:
Additionally suitable are bimetallic complexes of the general formula (U)
M1aM2bXm(L1)n (U)
These catalysts of the general formula (U) are known in principle from U.S. Pat. No. 6,084,033.
Particularly suitable catalysts are those of the general formula (U) in which M1 is rhodium and M2 is ruthenium. Other particularly suitable catalysts are those of the general formula (U) in which M2 is a lanthanide, especially Ce or La. In particularly suitable catalysts of the general formula (U), X are the same or different and are each H or Cl. Particularly suitable catalysts of the general formula (U) are those in which L1 is selected from trimethylphosphine, triethylphosphine, triphenylphosphine, triphenoxyphosphine, tri(p-methoxyphenyl)phosphine, diphenylethylphosphine, 1,4-di(diphenylphosphano)butane, 1,2-di(diphenylphosphano)ethane, triphenylarsine, dibutylphenylarsine, diphenylethylarsine, triphenylamine, triethylamine, N,N-dimethylaniline, diphenyl thioether, dipropyl thioether, N,N′-tetramethylethylenediamine, acetylacetone, diphenyl ketones and mixtures thereof.
Further catalysts which can be used are described in the following documents: U.S. Pat. No. 3,700,637. DE-A-25 39 132, EP-A 134 023, DE-A 35 41 689, DE 3540918, EP-A-0 298 386, DE-A 3529252, DE-A 3433 392, U.S. Pat. No. 4,464,515, U.S. Pat. No. 4,503,196 and EP-A-1 720 920.
For the hydrogenation of the nitrile rubber, the hydrogenation catalyst can be used within a wide range of amounts. Typically, the catalyst is used in an amount of 0.001 to 1.0% by weight, preferably from 0.01 to 0.5% by weight, especially 0.05 to 0.3% by weight, based on the nitrile rubber to be hydrogenated.
The practical performance of the hydrogenation is well known to those skilled in the art, for example from U.S. Pat. No. 6,683,136A.
The hydrogenation is typically effected in a solvent, preferably an organic solvent. Suitable organic solvents are, for example, acetone, methyl ethyl ketone, ethyl acetate, tetrahydrofuran, 1,3-dioxane, benzene, toluene, methylene chloride, chloroform, monochlorobenzene and dichlorobenzene. Monochlorobenzene has been found to be particularly useful, since it is a good solvent both for nitrile rubbers having different nitrile contents and for the corresponding resulting hydrogenated nitrile rubbers.
For the hydrogenation, nitrite rubber is typically dissolved in at least one solvent. The concentration of the nitrile rubber in the hydrogenation is generally in the range of 1-30% by weight, preferably in the range of 5-25% by weight, more preferably in the range of 7-20% by weight.
The pressure in the hydrogenation is typically within the range from 0.1 bar to 250 bar, preferably from 5 bar to 200 bar, more preferably from 50 bar to 150 bar. The temperature is typically within the range from 0° C. to 180° C., preferably from 20° C. to 160° C., more preferably from 50° C. to 150° C. The reaction time is generally 2 to 10 h.
In the course of the hydrogenation, the double bonds present in the nitrile rubber used are hydrogenated to the desired extent as already disclosed in the preceding parts of the application.
The hydrogenation is monitored online by determining the hydrogen absorption or by Raman spectroscopy (EP-A-0 897 933) or IR spectroscopy (U.S. Pat. No. 6,522,408). A suitable IR method for offline determination of the hydrogenation level is additionally described by D. Brick in Kautschuke+Gummi, Kunststoffe, Vol. 42. (1989), No. 2, p. 107-110 (part 1) and in Kautschuke+Gummi, Kunststoffe, Vol. 42. (1989), No. 3, p. 194-197.
On attainment of the desired hydrogenation level, the reactor is decompressed. Residual amounts of hydrogen are typically removed by nitrogen purging.
Before the isolation of the hydrogenated nitrile rubber from the organic phase, the hydrogenation catalyst can be removed. A preferred process for rhodium recovery is described, for example, in U.S. Pat. No. 4,985,540.
If the hydrogenation in the process according to the invention is effected with addition of a phosphine or diphosphine, these are typically used in amounts of 0.1 to 10% by weight, preferably of 0.25 to 5% by weight, more preferably 0.5 to 4% by weight, even more preferably 0.75 to 3.5% by weight and especially 1 to 3% by weight, based on the nitrile rubber to be hydrogenated.
Based on 1 equivalent of the hydrogenation catalyst, the phosphine or diphosphine, in a tried and tested manner, is used in an amount in the range from 0.1 to 10 equivalents, preferably in the range from 0.2 to 5 equivalents and more preferably in the range from 0.3 to 3 equivalents.
The weight ratio of the added phosphine or diphosphine to the hydrogenation catalyst is typically (1-100):1, more preferably (3-30):1, especially (5-15):1.
On completion of the hydrogenation, a hydrogenated nitrile rubber having a Mooney viscosity (ML 1+4 @ 100° C.), measured to ASTM Standard D 1646, in the range of 1-50 is obtained. This corresponds roughly to a weight-average molecular weight Mw in the range of 2000-400 000 g/mol. Preferably, the Mooney viscosity (ML 1+4 @ 100° C.) is in the range from 5 to 30. This corresponds roughly to a weight-average molecular weight Mw in the range of about 20 000-200 000. The hydrogenated nitrile rubbers obtained also have a polydispersity PDI=Mw/Mn where Mw is the weight-average and Mn the number-average molecular weight, in the range of 1-5 and preferably in the range of 1.5-3.
It is also possible to subject the nitrile rubber to a metathesis reaction before the hydrogenation, in order to lower the molecular weight of the nitrile rubber. The metathesis of nitrile rubbers is sufficiently well known to those skilled in the art. If a metathesis is effected, it is also possible to conduct the subsequent hydrogenation in situ, i.e. in the same reaction mixture in which the metathesis degradation has also been effected beforehand and without the need to isolate the degraded nitrile rubber. The hydrogenation catalyst is simply added to the reaction vessel.
Subsequently, the phosphine- or diphosphine-containing hydrogenated nitrile rubber is contacted with at least one of the defined oxidizing agents. This results in formation of the phosphine oxide or diphosphine oxide from the phosphine or diphosphine and hence in reduction extending as far as the complete removal of the amount of phosphine or diphosphine.
The phosphine- or diphosphine-containing hydrogenated nitrile rubber may either be in dissolved form or in solid form on contact with the oxidizing agent.
For the reaction of the phosphine- or diphosphine-containing hydrogenated nitrile rubbers, the two following alternative embodiments, for example, have been found to be useful:
In a first embodiment, the oxidizing agent can be added after the end of the hydrogenation and before or during the isolation of the hydrogenated nitrile rubber from the hydrogenation reaction mixture. Suitable methods for the isolation of the hydrogenated nitrile rubber from the organic solution are the vaporization of the organic solvent by the action of heat or of reduced pressure or by steam distillation. Preference is given to effecting a steam distillation. In this case, the subsequent removal of the rubber crumbs from the aqueous dispersion is effected by sieving and final mechanical and/or thermal drying. Preference is given to steam distillation. Depending on the pressure employed, the latter is conducted at a reaction temperature of typically 80 to 120° C., preferably about 100° C.
It has been found to be useful to add the oxidizing agent in organic or aqueous solution before or during the isolation of the hydrogenated nitrile rubber.
If the oxidizing agent is oil-soluble, the oxidizing agent is added to the hydrogenation reaction mixture in dissolved form, in which case the solvent for the solution of the oxidizing agent is appropriately identical to the solvent in which the phosphine- or diphosphine-containing hydrogenated nitrile rubber is present.
If the oxidizing agent is water-soluble, it is added to the hydrogenation reaction mixture as an aqueous solution and mixed well therewith.
Optionally, the addition of the oxidizing agent may be preceded by a catalyst recovery.
In a second embodiment, the phosphine- or diphosphine-containing hydrogenated nitrile rubber can be admixed and converted in the solid state with at least one oxidizing agent. In this form, it can be obtained by isolation from the hydrogenation reaction mixture. In that case, the phosphine- or diphosphine-containing hydrogenated nitrile rubber is in a substantially solvent-free state. Useful equipment for this embodiment has been found to be roll mills, internal mixers or extruders. Preference is given to using a roll mill or an internal mixer. A typical, commercially available roll mill is thermostatable and has two contra-rotating rolls. The oxidizing agent is incorporated with selection of a suitable roll temperature, for example in the range of 10-30° C., preferably at 20° C.+/−3° C., and of a suitable rotation speed, preferably in the range of 25 to 30 min−1, of a suitable roll nip, for example in the region of a few millimetres, and of a suitable rolling time, which is generally a few minutes. The milled rubber sheet obtained is subsequently typically cut and folded over and optionally applied to the roll once again.
In this embodiment, the oxidizing agent is typically also used in solid form.
The reaction of the phosphines or diphosphines with the oxidizing agent to give phosphine oxides or diphosphine oxides is effected at suitable temperatures depending on the reactivity of the oxidizing agent used. The reaction temperatures are preferably within the range from 10° C. to 150° C., more preferably within the range from 80° C. to 120° C. and especially within the range from 90° C. to 110° C. The reaction time for the reaction is typically within the range from 1 min to 5 h and can be determined by the person skilled in the art depending on the temperature selected.
Since the total halogen content of the inventive hydrogenated nitrile rubber is important, the person skilled in the art selects the oxidizing agents and/or amount thereof so as to comply with the critical value for the total halogen content in the nitrile rubber.
Oxidizing agents usable in the process according to the invention are the following compounds:
R—OO—R′ (I)
HXOn, (II)
Usable oxidizing agents (1) are, as well as ozone, hydrogen peroxide and salts thereof, preferably the alkali metal and alkaline earth metal salts, more preferably sodium peroxide, potassium peroxide, calcium peroxide and barium peroxide, and adducts of hydrogen peroxide, preferably addition compounds of hydrogen peroxide on boric acid and the corresponding salts, more preferably ammonium perborate, sodium perborate and potassium perborate.
Usable oxidizing agents (2) are peroxo compounds of the general formula (I) in which R and R′ are the same or different and are each hydrogen or an organic linear, branched, aromatic or alicyclic radical which may optionally contain one or more heteroatoms selected from the group consisting of oxygen, nitrogen, sulphur and halogen, but the two R and R′ radicals are not hydrogen at the same time.
Suitable oxidizing agents (2) are those of the general formula (I) in which R is hydrogen and each R′ is an organic radical which may optionally contain one or more heteroatoms selected from the group consisting of oxygen, nitrogen, sulphur and halogen. These oxidizing agents (2) include, for example, hydroperoxides, preferably cumyl hydroperoxide or p-menthane hydroperoxide and organic peracids and salts thereof, preferably performic acid, peracetic acid, perpropionic acid, perbenzoic acid or m-dichloroperbenzoic acid.
Suitable oxidizing agents (2) are also those of the general formula (I) in which the two R and R′ radicals are each an organic radical. These oxidizing agents include, for example, esters of the peracids.
Suitable oxidizing agents of group 3 are the following:
Suitable percarbonates are ammonium percarbonate, sodium percarbonate and potassium percarbonate.
Suitable salts of peroxodisulphuric acid are ammonium peroxodisulphate, sodium peroxodisulphate and potassium peroxodisulphate.
Suitable salts of perphosphoric acid (perphosphates) are ammonium peroxodiphosphate, sodium peroxodiphosphate and potassium peroxodiphosphate.
Suitable salts of permanganic acid (permnanganates) are ammonium permanganate, potassium permanganate and sodium permanganate.
Suitable perchromic acids are dichromic acid and polychromic acid. Suitable salts thereof are ammonium, sodium and potassium chromate, dichromate or polychromate.
Suitable oxidizing agents (4) are:
Halogens in the form of chlorine, bromine and iodine.
Examples of halogen-oxygen adds and their salts of the general formula (II) with n=1 are hypohalic acid and salts thereof (hypohalites), preferably sodium hypochlorite, or sodium hypobromite.
Examples of halogen-oxygen adds and their salts of the general formula (II) with n=3 are halic acid and salts thereof (halates), preferably chlorates, bromates, iodates, especially such as sodium chlorate, potassium chlorate or caesium iodate.
Examples of halogen-oxygen adds and their salts of the general formula (III) with n=4 are perhalic acids and salts thereof (perhalates), preferably perchlorates, perbromates or periodates.
Preferred oxidizing agents are hydrogen peroxide, sodium peroxide, potassium peroxide, barium peroxide, sodium perborate, sodium percarbonate, ammonium peroxodisulphate, iodine, sodium hypochlorite, potassium chlorate, potassium perchlorate, potassium permanganate, potassium dichromate, p-menthane hydroperoxide, cumyl hydroperoxide, performic acid, peracetic acid, perpropionic acid, perbenzoic acid, m-dichloroperbenzoic acid, benzoquinone and anthraquinone.
The amount of oxidizing agent used is calculated on the basis of the amount of phosphine or diphosphine present in the hydrogenation of the nitrile rubber. The molar amount of oxidizing agent is preferably 5 to 300%, preferably 50 to 150%, more preferably 75 to 125%, of the molar amount of the phosphine or diphosphine present in the hydrogenation beforehand.
The invention further provides vulcanizable mixtures comprising at least one inventive hydrogenated nitrile rubber and at least one crosslinking system. In addition, these vulcanizable mixtures may also comprise one or more further typical rubber additives.
These vulcanizable mixtures are produced by mixing at least one inventive hydrogenated nitrile rubber (i) with at least one crosslinking system (ii) and optionally one or more further additives.
The crosslinking system comprises at least one crosslinker and optionally one or more crosslinking accelerators.
Typically, the inventive hydrogenated nitrile rubber is first mixed with all the additives selected, and the crosslinking system composed of at least one crosslinker and optionally a crosslinking accelerator is the last to be mixed in.
Useful crosslinkers include, for example, peroxidic crosslinkers such as bis(2,4-dichlorobenzyl) peroxide, dibenzoyl peroxide, bis(4-chlorobenzoyl) peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, tert-butyl perbenzoate, 2,2-bis(t-butylperoxy)butene, 4,4-di-tert-butyl peroxynonylvalerate, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, tert-butyl cumyl peroxide, 1,3-bis(t-butylperoxyisopropyl)benzene, di-t-butyl peroxide and 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne.
It may be advantageous to use, as well as these peroxidic crosslinkers, also further additions which can help to increase the crosslinking yield: suitable examples thereof include triallyl isocyanurate, triallyl cyanurate, trimethylolpropane tri(meth)acrylate, triallyltrimellitate, ethylene glycol dimethacrylate, butanediol dimethacrylate, trimethylolpropane trimethacrylate, zinc diacrylate, zinc dimethacrylate, 1,2-polybutadiene or N,N′-m-phenylenedimaleimide.
The total amount of the crosslinker(s) is typically in the range from 1 to 20 phr, preferably in the range from 1.5 to 15 phr and more preferably in the range from 2 to 10 phr, based on the fully or partly hydrogenated nitrile rubber.
The crosslinkers used may also be sulphur in elemental soluble or insoluble form, or sulphur donors.
Useful sulphur donors include, for example, dimorpholyl disulphide (DTDM), 2-morpholinodithiobenzothiazole (MBSS), caprolactam disulphide, dipentamethylenethiuram tetrasulphide (DPFT) and tetramethylthiuram disulphide (TMTD).
It is also possible to use further additions which can help to increase the crosslinking yield in the sulphur vulcanization of the inventive hydrogenated nitrile rubbers. In principle, the crosslinking can also be effected with sulphur or sulphur donors alone.
Suitable additions which can help to increase the crosslinking yield are, for example, dithiocarbamates, thiurams, thiazoles, sulphenamides, xanthogenates, guanidine derivatives, caprolactams and thiourea derivatives.
Dithiocarbamates used may be, for example: ammonium dimethyldithiocarbamate, sodium diethyldithiocarbamate (SDEC), sodium dibutyldithiocarbamate (SDBC), zinc dimethyldithiocarbamate (ZDMC), zinc diethyldithiocarbamate (ZDEC), zinc dibutyldithiocarbamate (ZDBC), zinc ethylphenyldithiocarbamate (ZEPC), zinc dibenzyldithiocarbamate (ZBEC), zinc pentamethylenedithiocarbamate (Z5MC), tellurium diethyldithiocarbamate, nickel dibutyldithiocarbamate, nickel dimethyldithiocarbamate and zinc diisononyldithiocarbamate.
Thiurams used may be, for example, tetramethylthiuram disulphide (TMTD), tetramethylthiuram monosulphide (TMTM), dimethyldiphenylthiuram disulphide, tetrabenzyithiuram disulphide, dipentamethylenethiuram tetrasulphide or tetraethylthiuram disulphide (TETD).
Thiazoles used may be, for example, 2-mercaptobenzothiazole (MBT), dibenzothiazyl disulphide (MBTS), zinc mercaptobenzothiazole (ZMBT) or copper 2-mercaptobenzothiazole.
Sulphenamide derivatives used may be, for example, N-cyclohexyl-2-benzothiazylsulphenamide (CBS), N-ten-butyl-2-benzothiazylsulphenamide (TBBS), N,N′-dicyclohexyl-2-benzothiazylsulphenamide (DCBS), 2-morpholinothiobenzothiazole (MBS), N-oxydiethylenethiocarbamyl-N-tert-butylsulphenamide or oxydiethylenethiocarbamyl-N-oxyethylenesulphenamide.
Xanthogenates used may be, for example, sodium dibutylxanthogenate, zinc isopropyldibutylxanthogenate or zinc dibutylxanthogenate.
Guanidine derivatives used may be, for example, diphenylguanidine (DPG), di-o-tolylguanidine (DOTG) or o-tolylbiguanide (OTBG).
Dithiophosphates used may be, for example: zinc di(C2-C16)alkyldithiophosphates, copper di(C2-C16)alkyldithiophosphates and dithiophosphoryl polysulphide.
A caprolactam used may be, for example, dithiobiscaprolactam.
Thiourea derivatives used may be, for example, N,N′-diphenylthiourea (DPTU), diethylthiourea (DETU) and ethylenethiourea (ETU).
Crosslinking is also possible with crosslinkers having at least two isocyanate groups—either in the form of at least two free isocyanate groups (—NCO) or else in the form of two protected isocyanate groups from which the —NCO groups are released in situ under the crosslinking conditions.
Equally suitable as additions are, for example, zinc diaminodiisocyanate, hexamethylenetetramine, 1,3-bis(citraconimidomethyl)benzene and cyclic disulphanes.
The additions and crosslinking agents mentioned can be used either individually or in mixtures. Preference is given to using the following substances for the crosslinking of the inventive hydrogenated nitrile rubbers: sulphur, 2-mercaptobenzothiazole, tetramethylthiuram disulphide, tetramethylthiuram monosulphide, zinc dibenzyldithiocarbamate, dipentamethylenethiuram tetrasulphide, zinc dialkyldithiophosphate, dimorpholyl disulphide, tellurium diethyldithiocarbamate, nickel dibutyldithiocarbamate, zinc dibutyldithiocarbamate, zinc dimethyldithiocarbamate and dithiobiscaprolactam.
The crosslinking agents and aforementioned additions can each be used in amounts of about 0.05 to 10 phr, preferably 0.1 to 8 phr, especially 0.5 to 5 phr (single dose, based in each case on the active substance).
In the case of sulphur crosslinking, it is possible, in addition to the crosslinking agents and abovementioned additions, also to use further inorganic or organic substances as well, such as zinc oxide, zinc carbonate, lead oxide, magnesium oxide, saturated or unsaturated organic fatty acids and zinc salts thereof, polyalcohols, amino alcohols, for example triethanolamine, and amines, for example dibutylamine, dicyclohexylamine, cyclohexylethylamine and polyether amines.
If the inventive hydrogenated nitrile rubbers are those including repeating units of one or more termonomers containing carboxyl groups, crosslinking can also be effected via the use of a polyamine crosslinker, preferably in the presence of a crosslinking accelerator. The polyamine crosslinker is not restricted, provided that it is either (1) a compound that contains two or more amino groups (optionally also in salt form) or (2) a species that forms a compound that forms two or more amino groups in situ during the crosslinking reaction. Preference is given to using an aliphatic or aromatic hydrocarbon compound in which at least two hydrogen atoms are replaced either by amino groups or else by hydrazide structures (the latter being a “—C(═O)NHNH2” structure).
Examples of such polyamine crosslinkers (ii) are:
Particular preference is given to hexamethylenediamine and hexamethylenediamine carbamate.
The amount of the polyamine crosslinker in the vulcanizable mixture is typically in the range from 0.2 to 20 parts by weight, preferably in the range from 1 to 15 parts by weight and more preferably in the range from 1.5 to 10 parts by weight, based on 100 parts by weight of the hydrogenated nitrile rubber.
Crosslinking accelerators used in combination with the polyamine crosslinker may be any known to those skilled in the art, preferably a basic crosslinking accelerator. Usable examples include, for example, tetramethylguanidine, tetraethylguanidine, diphenylguanidine, di-o-tolylguanidine (DOTG), o-tolylbiguanidine and di-o-tolylguanidine salt of dicatecholboric acid. Additionally usable are aldehyde amine crosslinking accelerators, for example n-butylaldehydeaniline. More preferably at least one bi- or polycyclic aminic base is used as crosslinking accelerator. These are known to those skilled in the art. The following are especially suitable: 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]-5-nonene (DBN), 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD).
The amount of the crosslinking accelerator in this case is typically within a range from 0.5 to 10 parts by weight, preferably 1 to 7.5 parts by weight, especially 2 to 5 parts by weight, based on 100 parts by weight of the hydrogenated nitrile rubber.
The vulcanizable mixture based on the inventive hydrogenated nitrile rubber may in principle also contain scorch retardants, which differ between vulcanization with sulphur and with peroxides:
In the case of vulcanization with sulphur, the following are used: cyclohexylthiophthalimide (CTP), N,N′-dinitrosopentamethylenetetramine (DNPT), phthalic anhydride (PTA) and diphenylnitrosamine. Preference is given to cyclohexylthiophthalimide (CTP).
In the case of vulcanization with peroxides, scorch is retarded using compounds as specified in WO-A-97/01597 and U.S. Pat. No. 4,857,571. Preference is given to sterically hindered p-dialkylaminophenols, especially Ethanox 703 (Sartomer).
The further customary rubber additives include, for example, the typical substances known to those skilled in the art, such as fillers, filler activators, scorch retardants, antiozonants, ageing stabilizers, antioxidants, processing aids, extender oils, plasticizers, reinforcing materials and mould release agents.
Fillers used may, for example, be carbon black, silica, barium sulphate, titanium dioxide, zinc oxide, calcium oxide, calcium carbonate, magnesium oxide, aluminium oxide, iron oxide, aluminium hydroxide, magnesium hydroxide, aluminium silicates, diatomaceous earth, talc, kaolins, bentonites, carbon nanotubes, Teflon (the latter preferably in powder form), or silicates.
The amount of fillers is typically in the range from 5 to 350 parts by weight, preferably 5 to 300 parts by weight, based on 100 parts by weight of the hydrogenated nitrile rubber.
Useful filler activators include organic silanes in particular, for example vinyltrimethyloxysilane, vinyldimethoxymethylsilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, N-cyclohexyl-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane, isooctyltrimethoxysilane, isooctyltriethoxysilane, hexadecyltrimethoxysilane or (octadecyl)methyldimethoxysilane. Further filler activators are, for example, interface-active substances such as triethanolamine and ethylene glycols with molecular weights of 74 to 10 000 g/mol. The mount of filler activators is typically in the range from 0 to 10 phr, based on 100 phr of the hydrogenated nitrile rubber.
Ageing stabilizers added to the vulcanizable mixtures may, for example, be the following: polymerized 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), 2-mercaptobenzimidazole (MBI), methyl-2-mercaptobenzimidazole (MMBI) or zinc methylmercaptobenzimidazole (ZMMBI).
Alternatively, it is also possible to use the following, though less preferred, ageing stabilizers: aminic ageing stabilizers, for example in the form of mixtures of diaryl-p-phenylenediamines (DTPD), octylated diphenylamine (ODPA), phenyl-α-naphthylamine (PAN) and/or phenyl-β-naphthylamine (PBN). Preference is given to using those based on phenylenediamine. Examples of phenylenediamines are N-isopropyl-N′-phenyl-p-phenylenediamine, N-1,3-dimethylbutyl-N′-phenyl-p-phenylenediamine (6PPD), N-1,4-dimethylpentyl-N′-phenyl-p-phenylenediamine (7PPD) and N,N′-bis-1,4-(1,4-dimethylpentyl)-p-phenylenediamine (7PPD).
The ageing stabilizers are typically used in amounts of up to 10 parts by weight, preferably up to 5 parts by weight, more preferably 0.25 to 3 parts by weight, especially 0.4 to 1.5 parts by weight, based on 100 parts by weight of the hydrogenated nitrite rubber.
Examples of useful mould release agents include saturated or partly unsaturated fatty acids and oleic acids and derivatives thereof (fatty acid esters, fatty acid salts, fatty alcohols, fatty acid amides), which are preferably used as a mixture constituent, and also products applicable to the mould surface, for example products based on low molecular weight silicone compounds, products based on fluoropolymers and products based on phenol resins.
The amount of mould release agents is typically in the range from 0 to 10 phr, preferably 0.5 to 5 phr, based on 100 phr of the inventive hydrogenated nitrile rubber.
Another possibility is reinforcement with strengthening agents (fibres) made of glass, according to the teaching of U.S. Pat. No. 4,826,721, and another is reinforcement by cords, woven fabrics, fibres made of aliphatic and aromatic polyamides (Nylon®, Aramid®), polyesters and natural fibre products.
The mixing of the components for the purpose of producing the vulcanizable mixtures is typically effected either in an internal mixer or on a roll. Internal mixers used are typically those having what is called an intermeshing rotor geometry. At the starting point, the internal mixer is charged with the inventive hydrogenated nitrile rubber. This is typically in bale form and in that case is first comminuted. After a suitable period, which can be fixed by the person skilled in the art without difficulty, the addition of the additives and typically, at the end, of the crosslinking system is effected. The mixing is effected under temperature control, with the proviso that the mixture remains at a temperature in the range from 100 to 150° C. for a suitable time. After a suitable mixing period, the internal mixer is vented and the shaft is cleaned. After a further period, the internal mixer is emptied to obtain the vulcanizable mixture. All the aforementioned periods are typically in the region of a few minutes and can be fixed by the person skilled in the art without difficulty as a function of the mixture to be produced. If rolls are used as mixing units, it is possible to proceed in an analogous manner and sequence in the metered addition.
The invention further provides a process for producing vulcanizates based on the inventive hydrogenated nitrile rubbers, characterized in that the vulcanizable mixture comprising the inventive hydrogenated nitrile rubber is subjected to vulcanization. Typically, the vulcanization is effected at temperatures in the range from 100° C. to 200° C., preferably at temperatures of 120° C. to 190° C. and most preferably of 130° C. to 180° C.
The vulcanization is preferably effected in a shaping process.
For this purpose, the vulcanizable mixture is processed further by means of extruders, injection moulding systems, rolls or calenders. The preformed mass thus obtainable is typically then vulcanized to completion in presses, autoclaves, hot air systems, or in what are called automatic mat vulcanization systems, and useful temperatures have been found to be in the range from 120° C. to 200° C., preferably 140° C. to 190° C. The vulcanization time is typically 1 minute to 24 hours and preferably 2 minutes to 1 hour. Depending on the shape and size of the vulcanizates, a second vulcanization by reheating may be necessary to achieve complete vulcanization.
The invention accordingly provides the vulcanizates thus obtainable, based on the inventive hydrogenated nitrile rubbers.
These vulcanizates may take the form of a drive belt, of roller coverings, of a seal, of a cap, of a stopper, of a hose, of floor covering, of sealing mats or sheets, profiles or membranes. Specifically, the vulcanizates may be an O-ring seal, a flat seal, a shaft sealing ring, a gasket sleeve, a sealing cap, a dust protection cap, a connector seal, a thermal insulation hose (with or without added PVC), an oil cooler hose, an air suction hose, a power steering hose, a shoe sole or parts thereof, or a pump membrane.
Surprisingly, the phosphine oxides or diphosphine oxides formed in the hydrogenated nitrile rubber in the process according to the invention by the reaction of phosphines or diphosphines with the specific oxidizing agents disrupt neither the vulcanization characteristics thereof nor the vulcanizate properties of the hydrogenated nitrile rubber. In this respect, the present invention makes it possible to conduct the catalytic hydrogenation of nitrile rubber with a high reaction rate and simultaneously small amounts of catalyst and at lower pressure with hydrogenation catalysts having at least one phosphine or diphosphine ligand, and/or with phosphines/diphosphines as cocatalysts, and nevertheless to obtain hydrogenated nitrile rubbers and hence vulcanizates having the desired profile of properties. The vulcanizates obtained feature a reduced compression set and elevated moduli, and also have good values for heat buildup.
The triphenylphosphine and triphenylphosphine oxide contents in the hydrogenated nitrile rubber were determined by means of gas chromatography using an internal standard. For the determination, 2 to 3 g±0.01 g of HNBR in each case were weighed into a small test tube and dissolved with 25 ml of acetone, a known amount of an internal standard (docosane from Sigma-Aldrich; CA: 629-97-0) was added and, after mixing thoroughly, precipitation was effected by adding 50 ml of methanol. The precipitation serum was separated by means of gas chromatography using a capillary column (e.g.: HP-5, 0.25 μm film, 30 m×0.32 mm ID).
Under the given conditions, TPP, TPP═O and the internal standard have the following retention times:
For quantitative determination of the amounts of TPP and TPP═O present in HNBR, response factors of TPP/n-docosane and of TPP═O/docosane were used, which had been determined beforehand in independent measurements relating to the linear calibration range.
Where “<0.01% by wt.” is reported under TPP contents in the tables which follow, this means that (any) TPP content was below the analytical detection limit.
The hydrogenated nitrile rubber (amount between 2 mg and 10 mg, according to the halogen content) is weighed into a quartz crucible, which is pushed into a hot quartz tube using a solids module and combusted therein under an oxygen stream (ultrapure oxygen) (combustion tube temperature about 1000° C.). The combustion gases are introduced into a titration cell which has been initially charged with 75% by volume acetic acid, first through a trap filled with concentrated sulphuric acid (ultrapure) for drying, and then through a bubble breaker, and subsequently through a wash bottle filled with concentrated sulphuric acid to scavenge nitrogen oxides. In the titration cell, the halide ions are titrated with Ag+ ions which are produced by a silver anode up to the original cell equilibrium. The result in equivalents of Ag+ is converted to equivalents of halide and this result is reported hereinafter as “total halogen content” (based on chloride).
The exact hydrogenation levels were determined after the hydrogenation had ended by the methods described in Kautschuk+Gummi. Kunststoffe, vol. 42 (1989), no. 2, 107-110 and Kautschuk+Gummi, Kunststoffe, vol. 42 (1989), no. 3, 194-197.
For the hydrogenation experiments, the starting materials used were three different nitrile rubbers A, B and C. In the first step, for this purpose, three nitrile rubber latices A, B and C were produced on the basis of the polymer formulations specified in Tables Ia and Ib.
1)sodium salt of a mixture of mono- and disulphonated naphthalenesulphonic acids with isobutylene oligomer substituents (Erkantol ® BXG)
2)sodium salt of methylene bis(naphthalenesulphonate) (Baykanol ® PQ, Lanxess Deutschland GmbH)
3)Aldrich cataloge number: 21.622-4
4) Aldrich catalogue number: T5,830-0
5) Aldrich catalogue number: 15.795-3
6)t-DDM (tertiary dodecyl mercaptan): C12 mercaptan mixture from Lanxess Deutschland GmbH
1) Edenor ® HTiCT N (Oleo Chemicals)
2) trisodium phosphate* 12 H2O (Acros, item number 206520010) - calculation excluding water of crystallization
3) ethylenediaminetetraacetic acid (Fluka, item number 03620)
4) sodium formaldehydesulphoxylate 2-hydrate (Merck-Schuchardt, item number 8.06455), calculation excluding water of crystallization
5) Trigonox ® NT 50 (Akzo-Degussa), calculated to 100%
6) isomer mixture of tert-dodecyl mercaptans (Lanxess Deutschland GmbH)
After the removal of the unconverted monomers by means of steam distillation, the nitrile rubber latices A, B and C had the properties listed in Table Ic.
The nitrile rubbers A, B and C were stabilized prior to or in the course of coagulation with 0.35% by weight of Vulkanox® BKF (2,2-methylenebis(4-methyl-6-tert-butylphenol) from Lanxess Deutschland GmbH). For this purpose, Vulkanox® BKF was added to the corresponding nitrile rubber latices in the form of an aqueous dispersion.
The aqueous Vulkanox® BKF dispersion was based on the following formulation, prepared at 95 to 98° C. with the aid of an Ultraturrax:
In the case of latex A, the Vulkanox® BKF dispersion was added prior to coagulation. Nitrile rubber latex A was coagulated with MgCl2/gelatin as per Example 10 from EP-A-2 238 177. The washing and drying of the rubber crumbs was likewise effected according to EP-A-2 238 177.
Nitrile rubber latices B and C were coagulated according to Example 2 from EP-A-1 369 436. For this purpose, the latex was diluted to a solids concentration of 16.5% by weight with deionized water prior to coagulation. The aqueous dispersion of Vulkanox® BKF was added in the precipitation nozzle. The washing and drying were effected like Example 2 of EP 1369436.
The properties of the nitrile rubbers produced in this way are described in Table II.
Before the performance of the hydrogenation, exclusively the nitrite rubber B used in Experiment Series 3 was subjected to a metathesis. The metathesis was conducted in analogy to the examples of WO-A-02/100905, using 0.05 phr of Grubbs II catalyst (Materia/Pasadena) and 2.0 phr of 1-hexene in chlorobenzene solution at a solids concentration of the nitrile rubber of 12% by weight at 80° C. The metathesis degradation reduced the Mooney viscosity (ML 1+4 @ 100° C.) from 34 MU to 22 MU.
7 experiment series were conducted; an overview of them is given in Table 1.
In Experiment Series 1a and 1b, hydrogenated nitrile rubbers which had been obtained by hydrogenating nitrile rubber A in 16.67% chlorobenzene solution at a hydrogen pressure of 190 bar and a temperature of 120° C. to 130° C. were used. In each of the hydrogenations, 5 kg of the abovementioned nitrile rubber were dissolved in 24.5 kg of chlorobenzene in a 40 l autoclave. Before the hydrogenation, each polymer solution was successively contacted once with nitrogen (20 bar) and twice with hydrogen (20 bar) while stirring, and then decompressed. After injecting hydrogen to 190 bar, the amounts of TPP specified in the tables (Merck Schuchardt OHO; cat. no. 8.08270) were metered in as a solution in 250 g of chlorobenzene. The hydrogenation was started by adding 0.075% by weight (based on nitrile rubber) of tris(triphenylphosphine)rhodium(1) chloride (Evonik-Degussa) as a solution in 250 g of chlorobenzene. The course of the hydrogenation was monitored online by determining the hydrogen absorption. The hydrogenations were stopped at hydrogenation levels of 99.5±0.2% by cooling the reaction mixture. Subsequently, the mixtures were decompressed. Residual amounts of hydrogen were removed by passing nitrogen through.
For Experiment Series 2, 3, 4a, 4b, nitrile rubbers A and B were hydrogenated under the following boundary conditions:
In Experiment Series 1a, 1b, 2, and also 7a and 76, there was no removal of the rhodium catalyst used in the hydrogenation. In Experiment Series 3, 4a and 4b. the catalyst was removed after the hydrogenation as described in Example 5 of U.S. Pat. No. 4,985,540, using the thiourea-containing ion exchange resin from this Example 5. For the removal of rhodium, the solutions of the hydrogenated nitrile rubber in chlorobenzene were diluted to a solids concentration of 5% by weight.
VI Reaction of the Hydrogenated Nitril Rubber with Oxidizing Agents
The oxidizing agents used were the compounds specified in Table VI:
The aqueous solution of sodium hypochlorite (J) used in the experiments was prepared in accordance with the following reaction equation: 2 NaOH+Cl2→NaOCl+NaCl+H2O
The preparation was effected in a stirrable 10 l four-neck flask with thermometer, gas inlet tube with bubble counter and offgas line. 1370 g of sodium hydroxide were dissolved in an initial charge of 6150 g of deionized water while cooling with an ice bath. While cooling with the ice bath, 1200 g of chlorine gas were introduced at 5-10° C. over a period of 6 h. At the end of the reaction, the pH of the aqueous sodium hypochlorite solution was adjusted to >12.5 with 50 g of aqueous sodium hydroxide solution (48%). The content of active sodium hypochlorite in the aqueous solution was determined by iodometry (14.4%).
The reaction of the triphenylphosphine-containing hydrogenated nitrile rubbers A, B and C with the oxidizing agents was effected in two experimental variants:
The addition of the oxidizing agents to the chlorobenzene solutions of the triphenylphosphine-containing hydrogenated nitrile rubbers was effected before commencement of the steam distillation:
The steam distillation was effected batchwise in a stripping tank. The stripping tank was initially charged with the chlorobenzene solution of the hydrogenated nitrile rubber, and also deionized water and the oxidizing agent, at room temperature. The mixture was heated to 90° C. while stirring, without introduction of steam. On attainment of this temperature, the introduction of steam was commenced (at standard pressure) via a ring nozzle at the base of the stripping vessel. In the course of this, the vapours consisting of chlorobenzene and steam distilled off at a top temperature of 102° C. The vapours were condensed and separated into a chlorobenzene phase and an aqueous phase. As soon as chlorobenzene no longer separated out of the vapours (ca. 3 h), the steam distillation was stopped. The hydrogenated nitrile rubber, which was in the form of relatively coarse lumps, was isolated, cut into small pieces and dried to constant weight in a vacuum drying cabinet at 70° C. and a gentle air stream.
In Experiment Series 5, 6a and 6b, the oxidizing agents were mixed in in solid form on a roll mill. A detailed description of the procedure is given for the respective experimental series.
To determine the mixture and vulcanizate properties of the hydrogenated nitrile rubbers obtained in the experiments, rubber mixtures having the composition specified in Table VIII were produced.
The mixture was produced in a laboratory kneader of capacity 1.51 (GK 1.5 from Werner & Pfleiderer, Stuttgart, with intermeshing kneading elements (PS 5A—paddle geometry)), which had been preheated to 50° C. The mixture constituents were added in the sequence specified in the table.
To assess the processing characteristics of the unvulcanized rubber mixtures, Mooney viscosities at 100° C. after 1 min (ML1+1/100° C.) and after 4 minutes (ML1+4/100° C.), and at 120° C. after 4 min (ML1+4/120° C.), were determined to ASTM D1646.
The vulcanization characteristics of the mixtures were determined to ASTM D 5289-95 at 180° C., using both a Bayer-Frank vulcameter (from Agfa) and a moving die rheometer (MDR2000 from Alpha Technology). Characteristic vulcameter values such as Fmin, Fmax, Fmax−Fmin. are obtained in the dimension cN in the case of the Bayer-Frank vulcameter, and in the dimension dNm in the case of the moving die rheometer. Characteristic times such as t10, t50, t90 and t95 are determined in min or sec irrespective of the test method.
According to DIN 53 529, Part 3, the following characteristics have the following meanings:
Fmin: vulcameter value at the minimum of the crosslinking isotherm
Fmax: vulcameter value at the maximum of the crosslinking isotherm
Fmax-Fmin: difference in the vulcameter values between maximum and minimum
t10: time at which 10% of the final conversion has been attained
t50: time at which 50% of the final conversion has been attained
t90: time at which 90% of the final conversion has been attained
t95: time at which 95% of the final conversion has been attained
The vulcanization rate is obtained as the difference t90−t10 and the vulcanization level as the difference Fmax−Fmin.
The specimens used for the vulcanizate characterization were produced in a press at 180° C. at a hydraulic pressure of 120 bar (the vulcanization times are noted in the descriptions of the experiment series). The vulcanizates of some experiment series were subjected to a heat treatment in a heating cabinet, as noted in the corresponding tables, prior to the characterization.
Using the vulcanizates, the following properties were determined to the standards specified:
In a Goodrich flexometer (DIN 53533), the increase in temperature was determined after dynamic stress. The measurements were conducted at 100° C., a prestress of 1.0 MPa, a stroke of 4.00 mm and a stress time of 25 min. The lower the temperature increase after 25 min (heat buildup), the better the vulcanizate.
The compression set (CS) was determined to DIN 53517, by compressing a cylindrical specimen by 25% and storing it in the compressed state for the periods and at the temperatures specified in the tables (e.g. 70 h/23° C. or 70 h/150° C.). After relaxation of the samples, the lasting deformation (compression set) of the sample was determined. For the determination, cylindrical specimens having different dimensions were used (specimen 1: height: 6.3; diameter: 13 mm; specimen 2: height: 12.7; diameter: 28.7 mm).
The lower the lasting deformation, the better the compression set of a sample; in other words, 0% lasting deformation is very good and 100% is very poor.
To demonstrate the effect of the invention. Experiment Series 1 to 7 were conducted, giving the following results:
In Experiment Series 1a and 1b, the amount of TPP used in the hydrogenation was varied. The properties determined after the isolation of the hydrogenated nitrile rubber from the chlorobenzene solution (contents of triphenylphosphine and triphenylphosphine oxide and Mooney values are summarized in Table 1a).
Experiment Series 1a shows that increasing the amount of TPP reduces the hydrogenation times. With increasing amount of TPP, there is a deterioration in the modulus level and compression set of the vulcanizates produced on the basis of the hydrogenated nitrile rubbers (Experiment Series 1b).
The noninventive hydrogenated nitrile rubbers obtained in this Experiment Series have TPP contents of <0.01 to 1.72% by weight and TPP═O contents of <0.01 to 0.13% by weight.
In Experiment Series 2, hydrogenated nitrile rubbers were isolated from the chlorobenzene solution in the presence of oxidizing agents by steam distillation. The rhodium catalyst used for the hydrogenation was not removed prior to the performance of the steam distillation and was thus left in the solution of the hydrogenated nitrile rubber.
In Experiment Series 3, the rhodium hydrogenation catalyst was removed prior to the reaction with oxidizing agents. The reaction with the oxidizing agents thus took place in the absence of the hydrogenation catalyst. In addition, the nitrile rubber in Experiment Series 3 was degraded by means of metathesis prior to the hydrogenation.
It was shown that it is possible with various oxidizing agents, which are used in different molar oxidizing agent/TPP ratios, to reduce the TPP contents while simultaneously increasing the TPP═O contents (comparison of the inventive examples with reference experiments 3.0 and 4.0).
In the inventive examples of Experiment Series 2, the TPP contents were in the range from 0 to 0.65% by weight, the TPP═O contents in the range from 0.46 to 1.0% by weight and the total halogen contents in the range from 260 to 3100 ppm.
In the inventive examples of Experiment Series 3, the TPP contents were in the range from >0 to 0.42% by weight, the TPP═O contents in the range from 0.49 to 0.84% by weight and the total halogen contents in the range from 340 to 900 ppm.
In Experiment Series 4a and 4b, it was shown that the properties of vulcanizates of the hydrogenated nitrile rubber were surprisingly improved by inventive treatment with oxidizing agents. More particularly, the modulus level was increased and the compression set and heat buildup were reduced. The improvement in properties is independent of the amount of TPP used in the hydrogenation (experiments with 1.0 and 3.0% by weight of triphenylphosphine). In Comparative Example 4.4 using tetrachlorobenzoquinone, there is a significant increase in the total halogen content>10 000 ppm, and the corresponding vulcanizate has a much worse compression set (70 h/150° C.) and heat buildup. In contrast, the good compression set values and heat buildup were maintained at a total halogen content of 6600 ppm (Example 4.3*). The hydrogenated nitrile rubbers produced in accordance with the invention from Examples 4.1*, 4.3* and 4.5* have TPP contents up to 0.85% by weight, TPP═O contents of 1.1 to 2.7% by weight and total halogen contents of 420 to 6600 ppm.
In Experiment Series 1-4, the reaction of the TPP present in the hydrogenated nitrile rubber with oxidizing agents was effected during the isolation from the chlorobenzene solution by steam distillation. In contrast, in Experiment Series 5, the TPP oxidation was effected in the solid state on a roll.
In Experiment Series 5, hydrogenated nitrile rubber produced using 2.9 parts by weight of triphenylphosphine per 100 g of NBR (11.06 mmol/100 g NBR) was reacted with oxidizing agents in the solid state on a roll. For the experiments, a thermostatable roll mill having two contra-rotating rolls (from Schwabenthan; model: Polymix 110; roll diameter 110 mm) was used. The oxidizing agents were incorporated into 450 g of rubber each time, at a roll temperature of 20° C., rotational speeds of 25 and 30 min−1, at a roll nip of 3 mm, within a period of 4 min, by cutting into the milled rubber sheet and folding it over. After removing the milled rubber sheet, the roll was heated to the temperatures specified in Table 5, and the rubber mixtures were treated under the conditions specified in the tables.
It was shown that a reduction in the TPP content with the aid of oxidizing agents is possible when the oxidation is conducted without use of solvents on a roll mill. The molar ratios of oxidizing agent/triphenylphosphine are 1.03/1 or 1.04/1 and 0.52/1. The experiments were conducted with a fully hydrogenated nitrile rubber having 39% by weight of acrylonitrile (without metathesis degradation), which was hydrogenated using 2.9 parts by weight of TPP. After the reaction with oxidizing agents, the hydrogenated nitrile rubbers produced in accordance with the invention contain TPP within the range from 0.01 to 0.78% by weight, TPP═O within the range from 1.18 to 2.70% by weight and total halogen within the range of 47 to 54 ppm.
In Experiment Series 6a, the TPP oxidation was effected as in Series 5 in the solid state on a roll.
In Experiment Series 6a too, hydrogenated nitrile rubber produced using 2.9 parts by weight of TPP per 100 g of NBR (11.06 mmol/100 g NBR) was reacted with oxidizing agents in the solid state on a roll. For the experiments, the thermostatable roll mill from Experiment Series 5 was used. The oxidizing agents were incorporated into 450 g of rubber each time, at a roll temperature of 20° C., rotational speeds of 25 and 30 min−1, at a roll nip of 3 mm, within a period of 4 min, by cutting into the milled rubber sheet and folding it over. After removing the milled rubber sheet, the roll was heated to the temperatures specified in Tables 5) and 6a), and the rubber mixtures were treated under the conditions specified in the tables.
It was shown using the example of a fully hydrogenated nitrile rubber having 39% by weight of acrylonitrile (without metathesis degradation) that the addition of oxidizing agents improves the modulus level and compression set, with incorporation of the oxidizing agents into the solid hydrogenated nitrile rubber on the roll. In Inventive Examples 6.1* and 6.2*, the TPP contents are 0.82 and 0.78% by weight, the TPPO contents are 2.02% by weight and the total halogen contents are 51 and 60 ppm.
In Experiment Series 7a and 7b, the influence of TPP═O on the properties of the rubber mixtures and of the vulcanizates was examined. For this purpose, different amounts of TPP═O (see Experiment Series 7a) were added to the hydrogenated nitrile rubber from Experiment Series 1.1=7.1 on a temperature-controllable roll mill with two contra-rotating rolls (from Schwabenthan; model: Polymix 110; roll diameter: 110 mm). Each experimental setting was conducted twice with 450 g of rubber each time. The incorporation of TPP═O was effected at a roll nip of 3 mm (rotational speeds 25 and 30 min−1) at a roll temperature of 20° C. and a milled sheet temperature of 40° C., by repeatedly folding over and cutting into the milled sheet within a period of 5 min. After the incorporation of the TPP═O, the two milled sheets each having the same experimental setting were mixed on the roll, such that a total amount of 900 g was obtained for each experimental setting. Using these samples, the contents of TPP and TPP═O (Experiment Series 7a), and the properties of the rubber mixtures and vulcanizates summarized in Experiment Series 7b, were determined.
It was shown that the modulus level and compression set of HNBR vulcanizates are improved by additions of TPP═O. The TPP═O contents of the inventive hydrogenated nitrile rubbers were in the range of <0.01 to 2.01% by weight.
The results of the experiment series are summarized in the tables which follow. Inventive examples are each indicated by “*”.
Using the hydrogenated nitrile rubbers obtained in Experiment Series 1a, rubber mixtures having the composition specified in Table VIII were produced and vulcanized. The values reported in Table 1b were determined in the vulcanizates.
After the incorporation of the TPP═O, the two milled sheets each having the same experimental setting were mixed on the roll, such that a total amount of 900 g was obtained for each experimental setting. Using these samples, the contents of TPP and TPP═O (Experiment Series 6a), and the properties of the rubber mixtures and vulcanizates summarized in Experiment Series 7b, were determined.
| Number | Date | Country | Kind |
|---|---|---|---|
| 13199840.3 | Dec 2013 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2014/079376 | 12/29/2014 | WO | 00 |
