Patent Application
20160194413
The invention relates to a particulate olefin polymerization catalyst component, particularly one comprising a Group 2 metal and to a process for preparing same. The invention also relates to the use of such a catalyst component for preparing a catalyst, the activity maximum of which is shifted to a higher temperature used in the polymerization of olefins.
Ziegler-Natta (ZN) type polyolefin catalysts are well known in the field of polymers, generally, they comprise (a) at least a catalyst component formed from a transition metal compound of Group 4 to 6 of the Periodic Table (IUPAC, Nomenclature of Inorganic Chemistry, 1989), a metal compound of Group 1 to 3 of the Periodic Table (IUPAC), and, optionally, a compound of group 13 of the Periodic Table (IUPAC) and/or an internal donor compound. ZN catalyst may also comprise (b) further catalyst component(s), such as a cocatalyst and/or an external donor.
Various methods for preparing ZN catalysts are known in the state of art. In one known method, a supported ZN catalyst system is prepared by impregnating the catalyst components on a particulate support material. In WO-A-01 55 230, the catalyst component(s) are supported on a porous, inorganic or organic particulate carrier material, such as silica.
In a further well known method the carrier material is based on one of the catalyst components, e.g. on a magnesium compound, such as MgCl2. This type of carrier material can also be formed in various ways. EP-A-713 886 of Japan Olefins describes the formation of MgCl2 adduct with an alcohol which is then emulsified and finally the resultant mixture is quenched to cause the solidification of the droplets.
Alternatively, EP-A-856 013 of BP discloses the formation of a solid Mg-based carrier, wherein the Mg-component containing phase is dispersed to a continuous phase and the dispersed Mg-phase is solidified by adding the two-phase mixture to a liquid hydrocarbon.
The formed solid carrier particles are normally treated with a transition metal compound and optionally with other compounds for forming the active catalyst.
Accordingly, in case of external carriers, some examples of which are disclosed above, the morphology of the carrier is one of the defining factors for the morphology of the final catalyst.
One disadvantage encountered with the supported catalyst systems is that a possible surface treatment (impregnation step) of the support with one or more catalytically active compounds may lead to non-uniform distribution of the active component(s) and in turn to an inhomogeneous polymer material.
WO-A-00 08073 and WO-A-00 08074 describe further methods for producing a solid ZN-catalyst, wherein a solution of a Mg-based compound and one or more further catalyst compounds are formed and the reaction product thereof is precipitated out of the solution by heating the system. Furthermore, EP-A-926 165 discloses another precipitating method, wherein a mixture of MgCl2 and Mg-alkoxide is precipitated together with a Ti-compound to give a ZN catalyst.
EP-A-83 074 and EP-A-83 073 of Montedison disclose methods for producing a ZN catalyst or a precursor thereof, wherein an emulsion or dispersion of Mg and/or Ti compound is formed in an inert liquid medium or inert gas phase and said system is reacted with an Al-alkyl compound to precipitate a solid catalyst. According to examples said emulsion is then added to a larger volume of Al-compound in hexane and prepolymerised to cause the precipitation.
In general, a drawback of such precipitation methods is the difficulty to control the precipitation step and thus the morphology of the precipitating catalyst particles.
Furthermore, the precipitation of the catalyst component(s) may often proceed via a “tar-like” intermediate stage. Said undesired sticky precipitate agglomerates easily and sticks to the walls of the reactor. The morphology of the catalyst would then of course be lost.
WO 03/000757 describes a process for the preparation of an olefin polymerization catalyst component, enabling to prepare solid particles of a catalyst component comprising a group 2 metal together with a transition metal.
WO 2004/029112 discloses a further process for preparing an olefin polymerization catalyst component, wherein the process is further characterized in that a specific aluminum alkyl compound is brought into contact with the catalyst component, enabling a certain degree of activity increase at higher temperatures.
U.S. Pat. No. 5,413,979 describes a further method for the preparation of a solid procatalyst composition wherein support materials are impregnated with catalyst component precursors in order to obtain a catalyst component.
U.S. Pat. No. 4,294,948 finally discloses a process for preparing an olefin polymer or copolymer, employing a solid titanium catalyst component prepared by treating pulverized catalyst precursors with organo metallic compounds of a metal of any of groups I or III of the Periodic Table, characterized in that the catalyst preparation occurs using pulverized, solid and particulate precursor materials.
EP 1403292 A1, EP 0949280 A1, U.S. Pat. No. 4,294,948, U.S. Pat. No. 5,413,979 and U.S. Pat. No. 5,409,875 as well as EP 1273595 Al describe processes for the preparation of olefin polymerization catalyst components or olefin polymerization catalysts as well as processes for preparing olefin polymers or copolymers.
For some ZN-catalysts it is known in the art that the catalysts have their activity maximum at a relatively low temperature leading to a decreased or even drastically decreased catalyst activity, if polymerization is desired to carry out at higher temperature.
Accordingly, although much development work has been done in the field of Ziegler-Natta catalysts, there remains a need for alternative or improved methods of producing ZN catalysts with desirable properties.
It is of particular interest to obtain a catalyst in particulate form which results in good and desired polymer properties also when used in polymerization processes, where higher temperature are used. I.e. the object of the invention is to provide a catalyst component, yielding a catalyst having a high activity even at higher polymerisation temperatures. In addition it is very desired to have catalysts and further polymer products containing a decreased amount of catalyst residues, especially aluminium residues.
It has been surprisingly found by the inventors of the present invention that catalyst particles having a good morphology, size and uniform particle size distribution can be obtained by the way of preparing Ziegler-Natta (ZN) type catalysts, for use in olefin polymerization, in particular for propylene polymerisation, identified in the prior art cited above, showing furthermore an increase of activity at higher polymerization temperatures, illustrated herein by the high activity when using a polymerization temperature even of 80° C. shown in particular in the examples. In addition it can be shown that the catalyst activity is increased when using higher polymerisation temperatures, illustrated by increasing the polymerisation temperature from 70° C. to 80° C. The produced catalyst components according to the invention have excellent morphology, good particle size distribution and yield polymerisation catalysts having an activity maximum at higher temperatures. In addition to the high activity the catalysts have at the same time a very low Al content compared to the ones of prior art. According to the replica effect, the polymer particles produced by using the inventive catalyst have very good morphological properties, too. The inventive catalyst preparation is based on a liquid/liquid two-phase system where no separate external carrier materials such as silica or MgCl2 are needed in order to get solid catalyst particles.
As far as in the following specification and claims, the polymerization catalyst component is described by referring to a predetermined size range, this size range refers to the particle diameter, since the catalyst component particles as obtained in accordance with the present invention are almost perfect spheres for which the particle shape can be observed by microscopic techniques or the particle size distribution and the particle size range can be determined by using a Coulter Counter LS200 at room temperature (20° C.) with n-heptane as medium.
The present invention is therefore directed to a process for preparing an olefin polymerization catalyst component in the form of particles having a predetermined size range as defined in claim 1, said process comprising the steps of:
The catalysts known so far show often their highest polymerization activities (activity maximum) at temperatures of about 60 to 70° C. If the polymerization is carried out at a higher temperature, i.e. above 70° C., e.g. at around 80° C. or higher, as it is e.g. desirable in some specific processes, the activity of the catalyst is not high enough, because the activity maximum of normal catalyst is at lower temperature. The catalyst activity is in some cases at 80° C. about half the activity found at 70° C.
Polymerization processes, where the catalysts of the invention are useful comprise at least one polymerization stage. Typically the polymerization process comprises additional polymerization stages or reactors. In one particular embodiment the process contains at least one bulk reactor zone and at least one gas phase reactor zone, each zones comprising at least one reactor and all reactors being arranged in cascade. In one particularly preferred embodiment the polymerization process for polymerizing olefins, in particular propylene optionally with comonomers, like ethylene or other a-olefins, comprises at least one bulk reactor and at least one gas phase reactor arranged in that order. In some preferred processes the process comprises one bulk reactor and at least two gas phase reactors. The process may further comprise pre- and post reactors. Prereactors comprise typically prepolymerisation reactors. In these kinds of processes use of higher polymerization temperature (above 70° C., preferably 80° C. or higher, e.g. 85° C. or higher) either in some or all reactors of the reactor cascade, is preferred in order to achieve some specific properties to the polymers.
The inventors surprisingly found that by adding a small amount of an aluminium alkoxy compound as defined in claim 1, to the liquid/liquid two-phase system during the catalyst component preparation, a catalyst component is obtained yielding a polymerisation catalyst having a clearly improved activity at higher temperatures, like 80° C. or higher. In addition the polymerization activity maximum is shifted to higher temperatures, without destroying the excellent catalyst morphology or, subsequently, polymer morphology. In addition the aluminium content in the final catalyst is reduced notably, compared with the amount added to the catalysts component synthesis and is very small in the final catalyst.
The basic idea and target of the invention was to obtain a catalyst, having a high activity at higher temperatures. In practice from polymerization point of view this means that the new catalysts of the invention are very suitable for polymerization processes where higher temperature (>70° C.) are used, because they have their activity maximum at higher temperature range. This means that the catalyst activity remains about the same or is even improved when the polymerization is carried at higher temperature compared to the catalysts prepared without the aluminium alkoxy compound addition. It should be noted that the activity maximum of the catalyst is not necessary at one single temperature point but rather within a temperature range.
According to the results obtained by the inventors there seem to be three variables, which effect on the results, namely;
According to the findings of the inventors it appears to be decisive to add the aluminium compound before the particle formation has been completed so that the aluminium compound might serve as a kind of particle-internal cocatalyst. Accordingly, the addition of the aluminium compound may be started from step b) until the completion of the particle formation. The completion of the particle formation is usually achieved when the remaining toluene-soluble components have been washed out from the catalyst particles during solidifying said particles. Thus, the aluminium compound can be preferably added, in pure form or in the form of a solution, from shortly before the beginning of the emulsion formation until adding it to the washing liquid, mostly toluene, in such an amount that the final Al content of the particles is from 0,0 to 0,7%, preferably 0,02 to 0,5% and most preferably 0,04 to 0,3% by weight of the final catalyst particles. The most preferred Al content can vary depending on the type of the Al compound and on the adding step. E.g. in some cases the most preferred amount can be e.g. 0,01 to 0,2 wt %. The Al alkoxy compound to be employed in accordance with the present invention is added during the synthesis of the catalyst component in amounts of Al from 0.01 to 0,25 mol/mol of added metal of Group 2 in the form of Group 2 metal compound, more preferably 0.02 to 0.1 mol/mol of, most preferably 0,03 to 0,08 mol/mol of added Group 2 metal.
The inventors have surprisingly found, however, that the amount of the final Al content in the catalyst component is very small compared to the amount of Al added during the catalyst component preparation. In addition it has been found that the amount of added Al compound needs not to be very high. Without being bound to this theory, it is believed that this is mainly due to the type of Al compound used in the present invention. I.e. Al originating from Al alkoxy compounds apparently is removed more easily from the catalyst than the Al compounds originating from other type of Al compounds as employed in the prior art. However, they have the ability to increase the catalyst activity very effectively. According to the present invention it has thus now been found that by using a specific type of Al compound in catalyst component preparation, the activity at high polymerisation temperatures is increased and still the Al content in the final catalyst is reduced notably.
The inventors found out that the aluminum compounds to be used in the present invention as defined in claim 1 surprisingly enable a further activity increase at higher temperatures. Further, an additional feature is that the catalyst activity maximum is shifted to higher temperature as illustrated by the increase of catalyst activity shown in the examples, comparing catalyst activity at 70° C. and 80° C. The aluminium compounds to be employed in accordance with the present invention are characterized in that they comprise at least one alkoxy residue (R) as defined in claim 1, which is preferably a straight chain alkoxy group having from 1 to 6 carbon atoms, most preferably ethoxide. As is furthermore derivable from claim 1, the aluminium compound preferably comprises one or two alkoxy residues, most preferably one alkoxy residue.
In addition, the aluminium compound to be employed may comprise further residues, which independently can be selected from halogens and alkyl groups, preferably straight chain or branched alkyl groups having from 1 to 20, preferably 1 to 10 and more preferably 1 to 6 carbon atoms. Preferably, the aluminium compound to be employed in accordance with the present invention comprises one or two of such further residues (X), which may be identical or dissimilar, more preferably the aluminium compound to be employed in accordance with the present invention comprises two residues X, which preferably are identical. Suitable examples of groups represented by the residue X are halogens, in particular chlorine, bromine or iodine, or alkyl residues, preferably alkyl groups having from 1 to 6 carbon atoms and being straight chain alkyl groups, such as methyl, ethyl, propyl, butyl, pentyl or hexyl, preferably methyl, ethyl, propyl and/or butyl. In particular, preferably the aluminium compound to be employed in accordance with the present invention comprises as residue X one or two ethyl groups, most preferably two ethyl groups.
Illustrative examples of aluminium compounds to be employed in accordance with the present invention are diethyl aluminium ethoxide, ethyl aluminium diethoxide, diethyl aluminium methoxide, diethyl aluminium propoxide, diethyl aluminium butoxide, dichloro aluminium ethoxide, chloro aluminium diethoxide, dimethyl aluminium ethoxide, of which in particular diethyl aluminium ethoxide is preferred.
The new inventive method can be easily scaled up in order to avoid common up-scaling problems in the prior art which led to unsatisfied catalyst morphology and particle size distribution as well as reduced activity at higher temperature.
Preferably, the inventive process further comprises washing and drying said recovered solidified particles to obtain said catalyst component in a purified form.
The Group 2 metal used in step a) of the inventive process is preferably magnesium, and the liquid organic medium comprises preferably a C6-C10 aromatic hydrocarbon, preferably toluene.
As electron donor compound to be reacted with the Group 2 metal compound is preferably a mono- or diester of an aromatic carboxylic acid or diacid, the latter being able to form a chelate-like structured complex. Said aromatic carboxylic acid ester or diester can be formed in situ by reaction of an aromatic carboxylic acid chloride or diacid dichloride with a C2-C16 alkanol and/or diol, and is preferable dioctyl phthalate.
The reaction for the preparation of the Group 2 metal complex is generally carried out at a temperature of 20° to 80° C., and in case that the Group 2 metal is magnesium, the preparation of the magnesium complex is carried out at a temperature of 50° to 70° C.
The compound of a transition metal is preferably a compound of a Group 4 metal. The Group 4 metal is preferably titanium, and its compound to be reacted with the complex of a Group 2 is preferably a halide.
In a further embodiment of the invention, a compound of a transition metal used in the process can also contain organic ligands typically used in the field known as a single site catalyst.
In a still further embodiment of the invention, a compound of a transition metal can also be selected from Group 5 metals, Group 6 metals, Cu, Fe, Co, Ni and/or Pd compounds.
The complex of the Group 2 metal is preferably a magnesium complex. The invention will henceforth be described in relation to a preferred embodiment of the process, namely to a process for the preparation of a Ziegler-Natta type catalyst.
In a preferred embodiment, the present invention is directed to a process for producing catalysts of the Ziegler-Natta type in the form of particles having a predetermined size range, said process comprising: preparing a solution of magnesium complex by reacting an alkoxy magnesium compound and an electron donor or precursor thereof in a C6-C10 aromatic liquid reaction medium; reacting said magnesium complex with a compound of at least one four-valent Group 4 metal at a temperature greater than 10° C. and less than 60° C. to produce an emulsion of a denser, TiCl4/toluene-insoluble, oil dispersed phase having, Group 4 metal/Mg mol ratio 0.1 to 10 in an oil disperse phase having Group 4 metal/Mg mol ratio 10 to 100; agitating the emulsion, optionally in the presence of an emulsion stabilizer and or a turbulence minimizing agent, in order to maintain the droplets of said dispersed phase within an average size range of 5 to 200 μm. The catalyst particles are obtained after solidifying said particles of the dispersed phase e.g. by heating.
The said disperse and dispersed phases are thus distinguishable from one another by the fact that the denser oil, if contacted with a solution of titanium tetrachloride in toluene, will not dissolve in it. A suitable solution for establishing this criterion would be one having a toluene mol ratio of 0.1 to 0.3. They are also distinguishable by the fact that the great preponderance of the Mg provided (as complex) for the reaction with the Group 4 metal compound is present in the dispersed phase, as revealed by comparison of the respective Group 4 metal/Mg mol ratios.
In effect, therefore, virtually the entirety of the reaction product of the Mg complex with the Group 4 metal—which is the precursor of the ultimate catalyst component—becomes the dispersed phase, and proceeds through the further processing steps to the final particulate form. The disperse phase, still containing a useful quantity of Group 4 metal, can be reprocessed for recovery of that metal.
The production of a two-phase, rather than single-phase (as in prior practice) reaction product is encouraged by carrying out the Mg complex/Group 4 metal compound reaction at low temperature, specifically above 10° C. but below 60° C., preferably between above 20° C. and below 50° C. Since the two phases will naturally tend to separate into a lower, denser phase and supernatant lighter phase, it is necessary to maintain the reaction product as an emulsion by agitation, preferably in the presence of an emulsion stabiliser.
The resulting particles from the dispersed phase of the emulsion are of a size, morphology (spherical shape) and uniformity which render the ultimate catalyst component extremely effective in olefin polymerization. This morphology is preserved during the heating to solidify the particles, and of course throughout the final washing and optional drying steps. It is, by contrast, difficult to the point of impossibility to achieve such morphology through precipitation, because of the fundamental uncontrollability of nucleation and growth, and the large number of variables which affect these events.
The electron donor is preferably an aromatic carboxylic acid ester, a particularly favoured ester being dioctyl phthalate. The donor may conveniently be formed in situ by reaction of an aromatic carboxylic acid chloride precursor with a C2-C16 alkanol and/or diol. The liquid reaction medium preferably comprises toluene.
Furthermore, emulsifying agents/emulsion stabilisers can be used additionally in a manner known in the art for facilitating the formation and/or stability of the emulsion.
For the said purposes e.g. surfactants, e.g. a class based on acrylic or methacrylic polymers can be used. Preferably, said emulsion stabilizers are acrylic or methacrylic polymers, in particular those with medium sized ester side chains having more than 10, preferably more than 12 carbon atoms and preferably less than 30, and preferably 12 to 20 carbon atoms in the ester side chain. Particular preferred are unbranched C12 to C20 acrylates such as poly(hexadecyl)-methacrylate and poly(octadecyl)-methacrylate.
Furthermore, in some embodiments a turbulence minimizing agent (TMA) can be added to the reaction mixture in order to improve the emulsion formation and maintain the emulsion structure. By using said TMA, catalyst component particles can be obtained, said particles having very narrow size distribution.
Preferably, the TMA is added to the reaction mixture when the emulsion is formed, however in any case before solidification of the droplets of the dispersed phase starts in order to make sure that a quite uniform particle size distribution can be obtained.
Said TMA agent has to be inert and soluble in the reaction mixture under the reaction conditions, which means that polymers without polar groups are preferred.
Accordingly, said TMA or mixtures thereof are preferred as polymers having linear aliphatic carbon backbone chains, which might be branched with short side chains only in order to serve for uniform flow conditions when stirring. Said TMA is in particular preferably selected from α-olefin polymers of α-olefin monomers with 6 to 20 carbon atoms, like polyoctene, polynonene, polydecene, polyundecene or polydodecene or mixtures thereof, having the molecular weight and general backbone structure as defined before. Most preferable it is polydecene.
TMA can added to the emulsion in an amount of e.g. 1 to 1.000 ppm, preferably 5 to 100 ppm and more preferable 5 to 50 ppm, based on the total weight of the reaction mixture.
It has been found that the best results are obtained when the Group 4 metal/Mg mol ratio of the denser oil is 1 to 5, preferably 2 to 4, and that of the disperse phase oil is 55 to 65. Generally the ratio of the mol ratio Group 4 metal/Mg in the disperse phase oil to that in the denser oil is at least 10.
Solidification of the dispersed phase droplets by heating is suitably carried out at a temperature of 70-150° C., usually at 80-110° C., preferably at 90-110° C. .
The finally obtained catalyst component is desirably in the form of particles having generally an average size range of 5 to 200 μm, preferably 10 to 100, more preferably 20 to 50 μm.
The present invention further comprehends an olefin polymerization catalyst comprising a catalyst component prepared as aforesaid, in association with an alkyl aluminium cocatalyst and optionally donors, and the use of that polymerization catalyst for the polymerization Of C2 to C10-olefins.
The reagents can be added to the aromatic reaction medium in any order. However it is preferred that in a first step the alkoxy magnesium compound is reacted with a carboxylic acid halide precursor of the electron donor to form an intermediate; and in a second step the obtained product is further reacted with the Group 4 metal. The magnesium compound preferably contains from 1 to 20 carbon atoms per alkoxy group, and the carboxylic acid should contain at least 8 carbon atoms.
Reaction of the magnesium compound, carboxylic acid halide and polyhydric alcohol proceeds satisfactorily at temperatures in the range 20 to 80° C., preferably 50 to 70° C. The product of that reaction, the “Mg complex”, is however reacted with the Group 4 metal compound at a lower temperature, contrary to previous practice, to bring about the formation of a two-phase, oil-in-oil, product.
Use of an aromatic medium for preparation of the Mg complex contributes to consistent product morphology and higher bulk density. Catalyst bulk density and morphology correlate with polymer product bulk density and morphology according to the so-called “replication effect”.
The technique adopted in the novel regimen of the invention is inherently more precise than that formerly employed, and thus further contributes to product consistency, as well as sharply reducing the volumes of solvent to be handled and thus improving process economics.
The reaction medium used as solvent can be aromatic or a mixture of aromatic and aliphatic hydrocarbons, the latter one containing preferably 5-9 carbon atoms, more preferably 5-7 carbon atoms, or mixtures thereof. Preferably, the liquid reaction medium used as solvent in the reaction is aromatic and is more preferably selected from hydrocarbons such as substituted and unsubstituted benzenes, preferably from alkylated benzenes, even more preferably from toluene and the xylenes, and is most preferably toluene. The molar ratio of said aromatic medium to magnesium is preferably less than 10, for instance from 4 to 10, preferably from 5 to 9.
The recovered particulate product is washed at least once, preferably at least twice, most preferably at least three times with a hydrocarbon, which preferably is selected from aromatic and aliphatic hydrocarbons, preferably with toluene, particularly with hot (e.g. 80 to 100° C.) toluene, which might include a smaller or higher amount of TiCl4 in it. The amount of TiCl4 can vary from a few vol-% to more than 50 vol-%, such as from 5 vol-% to 50 vol-%, preferably up to 30 vol-% and more preferably from 5 to 15 vol-%. It is also possible that at least one wash is done with 100 vol-% TiCl4. One or several further washes after aromatic and/ or TiCl4 washes can be run with aliphatic hydrocarbons of 4 to 8 carbon atoms. Preferable these latter washings are performed with heptane and/or pentane. Washings can be done with hot (e.g. 90° C.) or cold (room temperature) hydrocarbons or combinations thereof. It is also possible that all washings will be done with the same solvent, e.g. toluene. According to the one preferred embodiment of the present invention the aluminium alkoxy compound to be used in the catalyst component preparation of the invention can be added to any of the washing mediums, however preferably not to the last or two last washings.
The washing can be optimized to give a catalyst component with novel and desirable properties. Finally, the washed catalyst component is recovered. It can further be dried, as by evaporation or flushing with nitrogen, or it can be slurried to an oily liquid without any drying step.
It is preferable that the intermediates as well as the final product of the process be distinct compounds with an essentially stoichiometric composition. Often, they are complexes. A complex is, according to Rompps Chemie-Lexicon, 7. Edition, Franckh'sche Verlagshandlung, W. Keller & Co., Stuttgart, 1973, page 1831, “a derived name of compounds of higher order, which originate from the combination of molecules,—unlike compounds of first order, in the creation of which atoms participate”.
The alkoxy magnesium compound group is preferably selected from the group consisting of magnesium dialkoxides, complexes of a magnesium dihalide and an alcohol, and complexes of a magnesium dihalide and a magnesium dialkoxide. It may be a reaction product of an alcohol and a magnesium compound selected from the group consisting of dialkyl magnesiums, alkyl magnesium alkoxides, alkyl magnesium halides and magnesium dihalides. It can further be selected from the group consisting of dialkyloxy magnesiums, diaryloxy magnesiums, alkyloxy magnesium halides, aryloxy magnesium halides, alkyl magnesium alkoxides, aryl magnesium alkoxides and alkyl magnesium aryloxides.
The magnesium dialkoxide may be the reaction product of a magnesium dihalide such as magnesium dichloride or a dialkyl magnesium of the formula R2Mg, wherein each one of the two Rs is a similar or different C1-C20 alkyl, preferably a similar or different C4-C10 alkyl. Typical magnesium alkyls are ethylbutyl magnesium, dibutyl magnesium, dipropyl magnesium, propylbutyl magnesium, dipentyl magnesium, butylpentylmagnesium, butyloctyl magnesium and dioctyl magnesium. Most preferably, one R of the formula R2Mg is a butyl group and the other R is an octyl group, i.e. the dialkyl magnesium compound is butyl octyl magnesium.
Typical alkyl-alkoxy magnesium compounds RMgOR, when used, are ethyl magnesium butoxide, butyl magnesium pentoxide, octyl magnesium butoxide and octyl magnesium octoxide.
Dialkyl magnesium, alkyl magnesium alkoxide or magnesium dihalide can react with a monohydric alcohol R′OH , or a mixture thereof with a polyhydric alcohol R′(OH)m.
Typical C1-C20 monohydric alcohols are methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec.butanol, tert.butanol, n-amyl alcohol, iso-amyl alcohol, sec.amyl alcohol, tert.amyl alcohol, diethyl carbinol, akt. amyl alcohol, sec. isoamyl alcohol, tert.butyl carbinol. Typical C6- C10 monohydric alcohols are hexanol, 2-ethyl-lbutanol, 4-methyl-2-pentanol, 1-heptanol, 2-heptanol, 4-heptanol, 2,4-dimethyl-3pentanol, 1-octanol, 2-octanol, 2-ethyl-l-hexanol, 1-nonanol, 5-nonanol, dilsobutyl carbinol, 1-decanol and 2,7-dimethyl-2-octanol. Typical >C10 monohydric alcohols are n-1-undecanol, n-1-dodecanol, n-l-tridecanol, n-l-tetradecanol, n-1-pentadecanol, 1-hexadecanol, n-l-heptadecanol and n-1 octadecanol. The monohydric alcohols may be unsaturated, as long as they do not act as catalyst poisons.
Preferable monohydric alcohols are those of formula R′OH in which R′ is a C2-C16 alkyl group, most preferably a C4-C12 alkyl group, particularly 2-ethyl-1-hexanol.
The aromatic reaction medium may also contain a polyalcohol, which may be straight- or branched-chain. Typical C2 to C6 polyhydric alcohols may be straight-chain or branched and include ethylene glycol, propylene glycol, trimethylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 2,3-butylene glycol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, pinacol, diethylene glycol, triethylene glycol, and triols such as glycerol, methylol propane and pentareythritol. The polyhydric alcohol can be selected on the basis of the activity and morphology it, gives the catalyst component.
Preferably, essentially all of the aromatic carboxylic acid ester is a reaction product of a carboxylic acid halide, preferably a dicarboxylic acid dihalide, more preferably an unsaturated α,β-dicarboxylic acid dihalide, most preferably phthalic acid dichloride, with the monohydric alcohol.
The compound of a fourvalent Group 4 metal compound containing a halogen is preferably a titanium tetrahalide. Equivalent to titanium tetrahalide is the combination of an alkoxy titanium halide and a halogenation agent therefore, which are able to form a titanium tetrahalide in situ. The most preferred halide is the chloride, for zirconium and hafnium as well as for titanium.
The reaction conditions used in the claimed process may be varied according to the used reactants and agents.
As is known, the addition of at least one halogenated hydrocarbon during the process can lead to further improved catalytic activity. Reactive halogenated hydrocarbons preferably have the formula R′″X′″n wherein R′″ is an n-valent C1-C20 hydrocarbyl group, particularly a C1-C10 paraffin, X′″ is a halogen and n is an integer from 1 to 4.
Such chlorinated hydrocarbons include monochloromethane, dichloromethane, trichloromethane (chloroform), tetrachloromethane, monochloroethane, (1,1)-dichloroethane, (1,2)-dichloroethane, (1,1,1)-trichloroethane, (1,1,2)-trichloroethane, (1,1,1,2)-tetrachloroethane, (1,1,2,2) tetrachloroethane, pentachloroethane, hexachloroethane, (1)-chloropropane, (2)-chioropropane, (1,2)-dichloropropane, (1,3)-dichloropropane, (1,2,3)trichloropropane, (1)-chlorobutane, (2)-chlorobutane, isobutyl chloride, tert.butyl chloride, (1,4)-dichlorobutane, (1)-chloropentane, (1,5)-dichloropentane. The chlorinated hydrocarbons may also be unsaturated, provided that the unsaturation does not act as catalyst poison in the final catalyst component.
In the above formula, R′″ is preferably a mono-or bivalent C1-C10 alkyl group, independently, X′″ is preferably chlorine and, independently, n is preferably 1 or 2. Preferred compounds include butyl chloride (BuCl), dichloroalkanes such as (1,4)-dichlorobutane, and tertiary butyl chloride.
Though the catalyst preparation according to the inventive method can be carried out batchwise, it is also preferable and possible to prepare the catalyst component semi-continuously or continuously. In such semi-continuous or continuous process, the solution of the complex of the group 2 metal and said electron donor, which is prepared by reacting the compound of said metal with said electron donor in an organic liquid reaction medium, is mixed with at least one compound of a transition metal, which might be solved in the same or different organic liquid reaction medium. The so obtained solution is then agitated, possibly in the presence of an emulsion stabilizer, and then the so-agitated emulsion is fed into a temperature gradient reactor, in which the emulsion is subjected a temperature gradient, thus leading to solidifying the droplets of a dispersed phase of the emulsion. The optional TMA is preferably contained in the solution of the complex or added to the solution before feeding the agitated solution to the temperature gradient reactor.
When feeding said agitated emulsion to the temperature gradient reactor, an inert solvent, in which the droplets are not soluble, can additionally be fed into that gradient reactor in order to improve the droplet formation and thus leading to a uniform grain size of the particles of the catalyst component, which are formed in the temperature gradient reactor when passing through said line. Such additional solvent might be the same as the organic liquid reaction medium, which is used for preparing the solution of the complex of the group 2 metal as explained above in more detail.
The solidified particles of the olefin polymerization catalyst component can subsequently be recovered by an in-stream filtering unit and then, optionally after some additional washing and drying steps in order to remove unreacted starting components, can be stored for further use. In one embodiment the catalyst can be fed after washing steps into the olefin polymerization reactor, so that a continuous preparation and feed to the reactor is guaranteed. It is also possible to mix the solidified and washed catalyst component with an oily fluidic liquid and store and use the catalyst component as a catalyst component-oil slurry. In this way the drying steps can be avoided, which might be sometimes detrimental to the catalyst components morphology. This oil-slurry method is described in general in EP1489110 of the applicant, incorporated herein by reference.
As it can be seen from the above description of the semi-continuous or continuous process, it is thus possible to use separated reaction vessels for the different process steps and to transfer the reaction products which are prepared in the respective reaction vessels and to feed them in-line into further reaction vessels for formation of the emulsion and, subsequently, of the solidified particles.
It is preferred to use a full-continuous process as the time saving in said process is remarkable. In such fully continuous process, the formation of the solidified particles could be carried out in the temperature gradient line in the kind of pipe reactor, which is sufficiently long and which is subjected said temperature gradient from the starting temperature in the lower range of 20 to 80° C. up to a “solidifying” temperature of 70 to 150° C. The temperature gradient is preferably obtained by means of heating the pipe reactor from the outside by applying normal heaters, microwaves, etc.
As mentioned before, a filtering unit might preferably be used for filtering the solidified particles from the solvent stream. For said filtering unit, various drums and sieving systems can be used, depending on the specific particle sizes.
Some preferred embodiments of the invention are described, by way of illustration, in the following examples.
In said examples, Examples 1 to 8, in accordance with the invention, illustrate the various modifications when to add the aluminium compound. Comparative Examples 1 to 3 are examples employing an aluminium compound not comprising an alkoxy residue.
In the examples the following measuring methods were used:
2.0 g of polymer are dissolved in 250 ml p-xylene at 135° C. under agitation. After 30±2 minutes the solution is allowed to cool for 15 minutes at ambient temperature and then allowed to settle for 30 minutes at 25±0.5° C. The solution is filtered with filter paper into two 100 ml flasks.
The solution from the first 100 ml vessel is evaporated in nitrogen flow and the residue is dried under vacuum at 90° C. until constant weight is reached.
XS %=(100×m1×v0)/(m0×v1)
Mw means weight average molecular weight and Mn is the number average molelecular weight determined in a known manner using size exclusion chromatograpy (SEC).
MWD means Mw/Mn, and is determined by said SEC method.
Rheology: Dynamic rheological measurements were carried out with Rheometrics RDA-II QC on compression molded samples under nitrogen atmosphere at 200° C. using 25 mm-diameter plate and plate geometry. The oscillatory shear experiments were done within the linear viscoelastic range of strain at frequencies from 0.01 to 500 rad/s. (ISO6721-1)
The values of storage modulus (G′), loss modulus (G″), complex modulus (G*) and complex viscosity (η*) were obtained as a function of frequency (ω).
The Zero shear viscosity (η0) was calculated using complex fluidity defined as the reciprocal of complex viscosity. Its real and imaginary part are thus defined by
f′(ω)=η′(ω)/[η′(ω)2+η″(ω)2] and
f″(ω)=η″(ω)/[η′(ω)2+η″(ω)2]
From the following equations
η′=G″/ω and η″=G′/ω
f′(ω)=G″(ω)*ω/[G′(ω)2+G″(ω)2]
f″(ω)=G′(ω)*ω/[G′(ω)2+G″(ω)2]
Shear thinning indexes (SHI), which are correlating with MWD and are independent of MW, were calculated according to Heino1, 2) (below).
SHI is calculated by dividing the Zero Shear Viscosity by a complex viscosity value, obtained at a certain constant shear stress value, G*. The abbreviation, SHI (0/50), is the ratio between the zero shear viscosity and the viscosity at the shear stress of 50 000 Pa.
1) Rheological characterization of polyethylene fractions. Heino, E. L.; Lehtinen, A; Tanner, J.; Seppälä, J. Neste Oy, Porvoo, Finland. Theor. Appl. Rheol., Proc. Int. Congr. Rheol., 11th (1992), 1 360-362
2) The influence of molecular structure on some rheological properties of polyethylene. Heino, Eeva-Leena. Borealis Polymers Oy, Porvoo, Finland. Annual Transactions of the Nordic Rheology Society, 1995
A magnesium complex solution was prepared by adding, with stirring, 78.0 kg of a 20% solution in toluene of butyloctylmagnesium (BOMAG A) to 27.1 kg 2-ethylhexanol in a 150 l steel reactor. During the addition the reactor contents were maintained below 35° C. After that 7.98 kg 1,2-phthaloyl dichloride was added and the reaction mixture was stirred for 60 minutes at 60° C. Solution was cooled to room temperature and stored.
19.5 ml titanium tetrachloride was placed in a 300 ml glass reactor equipped with a mechanical stirrer. Mixing speed was adjusted to 170 rpm and 32.0 g of the Mg-complex was added to the stirred reaction mixture over a 10-minute period. During the addition of the Mg-complex reactor content was maintained below 30° C. After that 1.0 ml of a solution in toluene of 2.0 mg polydecene and 2.0 ml Viscoplex 1-254 and 10 ml of heptane was added. The temperature of the reaction mixture was then raised to 90° C. over a period of 30 minutes and held at that level for 30 minutes with stirring.
After settling and siphoning, 100 ml of toluene containing 1.25 ml of diethyl aluminium ethoxide (Dealox) (10 vol %) was added to the reactor. After 30 minutes mixing solids were settled and liquid was siphonated. Then the solids were washed with 60 ml heptane for 20 minutes at 90° C. and with 60 ml pentane for 10 minutes at 25° C. Finally, the catalyst was dried at 60° C. by nitrogen purge.
Ti, Mg, Al and DOP contents in the catalyst are disclosed in Table 1.
Polymerization of propylene at 80° C. with the catalyst component was done in a 5 litre reactor with stirrer. Triethyl aluminium (TEA) (cocatalyst) (Al/Ti molar ratio 250), cyclohexyl methyl dimethoxy silane (external donor Do and Al/Do molar ratio 10) and 30 ml pentane were mixed and allowed to react for 5 minutes. Half of the mixture was added to the reactor and the other half was mixed with 19.4 mg of the catalyst component. After 10 minutes the catalyst/TEA/donor/pentane mixture was added to the reactor. 70 mmol hydrogen and 1400 g propylene were added into the reactor and the temperature was raised to 80° C. within 20 minutes while mixing. The reaction was stopped after 60 minutes at 80° C. by flashing out unreacted propylene with cooling. The results are shown in Table 2.
Polymerization of propylene at 70° C. was carried out as at 80° C. using 18.8 mg of the catalyst component. Activity at 70° C. was 25,6 kg PP/g cat.
The results are shown in Tables 2 and 3.
Magnesium complex was the same as in Example 1.
19.5 ml titanium tetrachloride was placed in a 300 ml glass reactor equipped with a mechanical stirrer. Mixing speed was adjusted to 170 rpm. 32.0 g of the Mg-complex was added to the stirred reaction mixture over a 10-minute period. During the addition of the Mg-complex the reactor content was maintained below 30° C. Then 1.0 ml of a solution in toluene of 3.0 mg polydecene and 2.0 ml Viscoplex 1-254 and 10 ml of heptane was added. The temperature of the reaction mixture was then slowly raised to 90° C. over a period of 30 minutes and held at that level for 30 minutes with stirring.
After settling and siphoning, 100 ml of toluene containing 1.25 ml of diethyl aluminium ethoxide (10 vol %) was added to the reactor. Then 30 ml of TiCl4 was added keeping the temperature at 90° C.
Then the solids were washed with 60 ml heptane for 20 minutes at 90° C. and with 60 ml pentane for 10 minutes at 25° C. Finally, the catalyst component was dried at 60° C. by nitrogen purge.
Ti, Mg, Al and DOP contents in the catalyst are disclosed in Table 1.
Polymerization of propylene at 80° C. was carried out as in Example 1 using 15.3 mg of the catalyst component.
Catalyst composition and polymerization results are shown in Tables 1, 2 and 3.
Magnesium complex was the same as in Example 1.
Preparation of the catalyst component was done as in Example 2, except Dealox amount was 1.5 ml.
Polymerization was carried out as in the Example 1 at 80° C. using 13.4 mg of the catalyst component and at 70° C. using 17.1 mg of the catalyst component. Activity at 70° C. was 39,9 kg PP/g cat.
Catalyst composition and polymerization results are shown in Tables 1, 2 and 3.
Magnesium complex was the same as in Example 1.
Preparation of the catalyst component was done as in Example 3, except TiCl4 wash was done at 100° C.
Polymerization was carried out at 80° C. as in the Example 1 using 15.2 mg of the catalyst component.
Catalyst composition and polymerization results are shown in Tables 1, 2 and 3.
Magnesium complex was the same as in Example 1.
Preparation of the catalyst component was done as in Example 3, except TiCl4 wash was done at 80° C.
Polymerization was carried out at 80° C. as in the Example 1 using 15.0 mg of the catalyst component.
Catalyst composition and polymerization results are shown in Tables 1, 2 and 3.
Magnesium complex was the same as in Example 1.
Preparation of the catalyst component was done as in Example 5, except Dealox amount was 2.5 ml.
Polymerization was carried out at 80° C. as in the Example 1 using 13.0 mg of the catalyst component.
Catalyst composition and polymerization results are shown in Tables 1, 2 and 3.
Magnesium complex was the same as in Example 1.
Preparation of the catalyst component was done as in Example 5, except that TiCl4 was diluted with toluene in a ratio of 1:3 (1 part (7.5 ml) TiCl4 and 3 parts (22.5 ml) toluene).
Polymerization was carried out at 80° C. as in Example 1 using 14.0 mg of the catalyst component.
Catalyst composition and polymerization results are shown in Tables 1, 2 and 3.
Magnesium complex was the same as Example 1.
19.5 ml titanium tetrachloride was placed in a 300 ml glass reactor equipped with a mechanical stirrer. Mixing speed was adjusted to 170 rpm and 32.0 g of the Mg-complex was added to the stirred reaction mixture over a 10-minute period. During the addition of the Mg-complex the reactor content was maintained blow 30° C. Then 1.5 ml Dealox was added to the reaction mixture. After that 1.0 ml of a solution in toluene of 2.0 mg polydecene and 2.0 ml Viscoplex 1-254 and 10 ml of heptane was added. The temperature of the reaction mixture was then raised to 90° C. over a period of 30 minutes and held at that level for 30 minutes with stirring.
After settling and siphoring, 30 ml of TiCl4 was added keeping the temperature at 90° C. After 30 minutes mixing solids were settled and liquid was siphonated. Then the solids were washed with 100 ml toluene for 30 minutes at 90° C., with 60 ml heptane for 20 minutes at 90° C. and with 60 ml pentane for 10 minutes at 25° C. Finally, the catalyst was dried at 60° C. by nitrogen purge. Polymerization was carried out at 80° C. as in Example 1 using 13.0 mg of the catalyst component.
Catalyst composition and polymerization results are shown in Tables 1, 2 and 3.
Magnesium complex was the same as Example 1.
19.5 ml titanium tetrachloride was placed in a 300 ml glass reactor equipped with a mechanical stirrer. Mixing speed was adjusted to 170 rpm. 1.0 ml of a solution in toluene of 3.0 mg polydecene and 2.0 ml Viscoplex 1-254, 32.0 g of the Mg-complex were added to the stirred reaction mixture over a 10-minute period. During the addition of the Mg-complex the reactor content was maintained below 30° C. After that, 10 ml heptane was added. The temperature of the reaction mixture was then slowly raised to 90° C. over a period of 30 minutes and held at that level for 30 minutes with stirring.
After settling and siphoning, 100 ml of toluene containing 0.33 ml of diethyl aluminium chloride was added to the reactor. After 30 minutes mixing solids were settled and liquid was siphonated. Then 30 ml of TiCl4 was added keeping the temperature at 90° C.
Then the solids were washed with 60 ml heptane for 20 minutes at 90° C. and with 60 ml pentane for 10 minutes at 25° C. Finally, the catalyst was dried at 60° C. by nitrogen purge.
Polymerization was carried out at 80° C. as in Example 1 using 19 mg of the catalyst component.
Catalyst composition and polymerization results are shown in Tables 1, 2 and 3.
Magnesium complex was the same as Example 1.
19.5 ml titanium tetrachloride were placed in a 300 ml glass reactor equipped with a mechanical stirrer. Mixing speed was adjusted to 170 rpm. After addition of 10.0 ml n-heptane, 1.0 ml of a solution in toluene of 3.0 mg polydecene and 2.0 ml Viscoplex 1-254, 32.0 g of the Mg-complex were added to the stirred reaction mixture over a 10 minute period. During the addition of the Mg-complex the reactor contents were maintained below 30° C.
The temperature of the reaction mixture was then slowly raised to 90° C. over a period of 20 minutes and held at that level for 30 minutes with stirring.
After settling and syphoning 100 ml toluene containing 0,10 ml of the aluminium compound (TEA, triethylaluminium) was added to the reaction mixture. After 30 minutes mixing the solids were settled and liquid was siphonated.
Then the solids were washed with 100 ml toluene at 90° C. for 30 minutes, 60 ml heptane for 20 minutes at 90° C. and 60 ml pentane for 10 minutes at 25° C. Finally, the solids were dried at 60 ° C. by nitrogen purge, to yield a yellow, air-sensitive powder.
Polymerization was carried out at 70° C. and 80° C. as in Example 1 using 18,6 mg of the catalyst component. Activity at 70° C. was 26,8 kg PP/g cat.
Catalyst composition and polymerization results are shown in Tables 1, 2 and 3.
The catalyst preparation was carried out as in Comparative Example 2, but the amount of TEA used was 0,50 ml.
Polymerization was carried out at 70° C. and 80° C. as in Example 1 using 17,4 mg of the catalyst component. Activity at 70° C. was 22,4 kg PP/g cat.
Catalyst composition and polymerization results are shown in Tables 1, 2 and 3.
The examples as contained in the present application, in particular in comparison with the comparative examples provided, clearly show that the addition of a specific type of aluminium compound as defined in the present invention surprisingly leads to a very high activity with respect to polymerizations at higher temperatures, and still the Al content in the final catalyst component is very low or even zero.
The activity and the Al content in the final catalyst are to some extent also dependent on the stage, where the Al content is added. It can be seen that by adding the Al compound together with the washing medium, the activity will be higher.
Low Al content is shown by the Al wt-% content in the catalyst component as well by the ratio of the Al in catalyst(mmol)/Al added (mmol) to the catalyst component synthesis. As can be seen in the examples the ratio Al in cat/Al added is much lower in the catalyst components prepared according to the present invention. It shows that the Al alkoxy compounds used in the invention apparently are removed more easily from the catalyst component. As a result a catalyst component is obtained yielding a catalyst having a very high activity at high polymerisation temperatures and still a low amount of Al in the final catalyst.
In addition good polymerisation results are obtained without detrimental effect on the polymer produced.
| Number | Date | Country | Kind |
|---|---|---|---|
| 06011312.3 | May 2006 | EP | regional |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12302567 | Aug 2009 | US |
| Child | 14990632 | US |
