This invention relates to the field of materials obtained by crosslinking of silicone compositions in which are put into contact reagents having at least two unsaturated bonds and organosilicon compounds having at least two hydrogenosilyated units (ESiH) in the presence of a catalyst C which is a complex corresponding to the following formula:
[Ni(L1)2]
in which the symbol Ni represents nickel at degree of oxidation II, and the symbols L′, which may be identical or different, represent a ligand which is a β-dicarbonylato anion or the enolate anion of a β-dicarbonylated compound.
In the field of silicone composition crosslinking, hydrosilylation, also referred to as polyaddition, is a preponderant reaction.
During a hydrosilylation reaction, a compound comprising at least one unsaturation reacts with a compound comprising at least one hydrogen atom bonded to a silicon atom. This reaction can for example be described by the reaction equation (1) in the case of an unsaturation of the alkene type:
or by the reaction equation (2) in the case of an unsaturation of the alkyne type:
The hydrosilylation of unsaturated compounds is carried out by catalysis, using an organometallic catalyst. Currently, the suitable organometallic catalyst for this reaction is a platinum catalyst. As such, most industrial hydrosilylation reactions are catalysed by the Karstedt platinum complex, of general formula Pt2(divinyltetramethyldisiloxane)3 (or in abbreviated form Pt2(DVTMS)3):
At the beginning of the 2000's, the preparation of platinum-carbene complexes of general formula:
made it possible to have access to more stable catalysts (see for example international patent application WO 01/42258).
However, the use of organometallic platinum catalysts is still problematic. This is a toxic metal, expensive, and is becoming scarce and of which the cost fluctuates enormously. Its use on an industrial scale is therefore difficult. It is therefore sought to reduce as much as possible the quantity of catalyst required for the reaction, without however reducing the yield and the speed of the reaction. Moreover, it is sought to have a catalyst that is stable during the reaction. It has been observed that, during the catalysed reaction, the metal platinum could precipitate, which has the consequence of forming insoluble colloids in the reaction medium. The catalyst is then less active. In addition, these colloids form a cloud in the reaction medium, and the products obtained are not satisfactory from an aesthetic standpoint as they are coloured.
Finally, platinum based complexes catalyse the hydrosilylation reactions at ambient temperature with a rapid kinetics, of about a few minutes. In order to have the time to prepare, transport and implement the composition before it hardens, it is often necessary to temporarily inhibit the hydrosilylation reaction. For example, when it is sought to coat a paper or polymer substrate with a non-stick silicone coating, the silicone composition is formulated to form a bath that must remain liquid at ambient temperature for several hours before being deposited on the substrate. It is only after this depositing that it is desired for the hardening by hydrosilylation to occur. The introduction of hydrosilylation inhibiting additives makes it possible to effectively prevent the reaction as long as necessary before activation. However, it is sometimes necessary to use large quantities of inhibiting agent, which causes a strong inhibition of the hydrosilylation catalyst. This results in that the speed of hardening of the composition, even after activation, is slowed down, which is a major disadvantage from an industrial standpoint as this in particular requires reducing the coating speed and therefore the speed of production.
It would therefore be interesting to propose organometallic catalysts as an alternative to platinum based catalysts and to have new silicone materials that are crosslinked and/or hardened by means of catalysts that no longer have the problems described hereinabove, in particular that do not require the use of an inhibiting agent.
This objective is achieved using a catalyst which is a complex of nickel (II) that has a specific structure. These catalysts, in particular, do not require manipulation under protected atmosphere (for example under argon). The crosslinking reactions wherein they are implemented can also be carried out in air, without protected atmosphere.
This invention thus has for object, according to a first aspect, a crosslinked silicone material Y obtained by heating to a temperature of between 70 and 200° C., preferably between 80 and 150° C., and more preferably between 80 and 130° C., a crosslinkable composition X comprising:
[Ni(L1)2]
in which:
The term “crosslinked silicone material” means any silicone based product obtained by crosslinking and/or hardening compositions comprising organopolysiloxanes having at least two unsaturated bonds and organopolysiloxanes having at least two hydrogenosilylated units (≡SiH). The crosslinked silicone material can for example be an elastomer, a gel or a foam.
The invention also has for object, according to a second aspect, a crosslinkable composition X such as described hereinabove.
The composition X according to the invention is crosslinkable, i.e., in terms of this application, once the compounds A and B have reacted together in the presence of the catalyst C, a three-dimensional network is formed, which leads to the hardening of the composition. The crosslinking therefore implies a progressive physical change of the medium constituting the composition.
The publications Bogdan Marciniec et al. “Catalyst of hydrosililation Part XXV. Effect of nickel (o) and nickel (II) complex catalysts on dehydrogenative silylation, hydrosilylation and dimerization of vinyltriethaxysilane”, Journal of Organometallic chemistry, vol. 484, no. 1-2, 27 Dec. 1994 and “Catalyst of hydrosililation Part XX. Unusual reaction of vinyltriethaxysilane with triethaxysilane catalyzed by nickel acetylacetonate”, Journal of Organometallic chemistry, Lausane JOM, 15 Oct. 1991, describe a hydrosilylation reaction between two silanes, vinyltriethoxysilane (EtO)3—Si-Vi and triethoxysilane (EtO)3—SiH, in the presence of catalysts of nickel (0) or (2). Silanes comprising the Si—H bond have as substituents ethoxy Si—O-Et units that are very specific and very different from the siloxanes according to this application which have alkyl and siloxy substituents.
The invention also has for object, according to a third aspect, the use of the previously described catalyst C as silicone composition crosslinking catalyst.
The invention further has for purpose, according to a fourth aspect, a silicone composition crosslinking method, characterised in that it consists in heating the previously described composition X to a temperature of between 70 and 200° C., preferably between 80 and 150° C., and more preferably between 80 and 130° C., as well as the crosslinked silicone material Y obtained as such.
According to a particularly advantageous embodiment, the organopolysiloxane A comprising, per molecule, at least two C2-C6 alkenyl radicals bonded to silicon atoms, comprises:
(i) at least two siloxyl units (A.1), which may be identical or different, of the following formula:
in which:
(ii) and optionally at least one siloxyl unit of the following formula:
in which:
Advantageously, the radicals Z and Z1 are chosen from the group consisting of a methyl and phenyl radical, and W is chosen from the following list: vinyl, propenyl, 3-butenyl, 5-hexenyl, 9-decenyl, 10-undecenyl, 5,9-decadienyl and 6-11-dodecadienyle, and preferably W is a vinyl.
These organopolysiloxanes can have a linear, branched, or cyclical structure. Their degree of polymerisation is, preferably, between 2 and 5000.
When it is a question of linear polymers, the latter are substantially constituted of siloxyl “D” units chosen from the group consisting of the siloxyl units W2SiO2/2, WZSiO2/2 and Z12SiO2/2, and siloxyl units “M” chosen from the group consisting of the siloxyl units W3SiO1/2, WZ2SiO1/2, W2ZSiO1/2 and Z13SiO1/2. The symbols W, Z and Z1 are such as described hereinabove.
By way of examples of “M” terminal units, mention can be made of the trimethylsiloxy, dimethylphenylsiloxy, dimethylvinylsiloxy or dimethylhexenylsiloxy groups.
By way of examples of “D” units, mention can be made of the dimethylsiloxy, methylphenylsiloxy, methylvinylsiloxy, methylbutenylsiloxy, methylhexenylsiloxy, methyldecenylsiloxy or methyldecadienylsiloxy groups.
Said organopolysiloxanes A can be oils with a dynamic viscosity of about 10 to 100,000 mPa·s at 25° C., generally about 10 to 70,000 mPa·s at 25° C., or gums that have a molecular weight of about 1,000,000 mPa·s or more at 25° C.
All of the viscosities of which it is a question in this disclosure correspond to a magnitude of dynamic viscosity at 25° C. referred to as “Newtonian”, i.e. the dynamic viscosity that is measured, in a manner known per se, with a Brookfield viscometer with a shear speed gradient that is low enough so that the viscosity measured is independent of the speed gradient.
When entailing cyclical organopolysiloxanes, the latter are constituted of siloxyl “D” units of the following formulas: W2SiO2/2, Z2SiO2/2 or WZSiO2/2, which can be of the dialkylsiloxy, alkylarylsiloxy, alkylvinylsiloxy, alkylsiloxy type. Examples of such siloxyl units have already been mentioned hereinabove. Said cyclic organopolysiloxanes A have a viscosity of about 10 to 5000 mPa·s at 25° C.
According to a preferred embodiment, the composition X according to the invention comprises a second organopolysiloxane compound comprising, per molecule, at least two C2-C6 alkenyl radicals bonded to silicon atoms, different from the organopolysiloxane compound A, said second organopolysiloxane compound being preferably divinyltetramethylsiloxane (dvtms).
Preferably, the organopolysiloxane compound A has a mass content of Si-vinyl unit between 0.001 and 30%, preferably between 0.01 and 10%.
According to a preferred embodiment, the organohydrogenopolysiloxane compound B is an organopolysiloxane having at least two hydrogen atoms, per molecule, bonded to an identical or different silicon atom and, preferably, having at least three hydrogen atoms per molecule directly bonded to an identical or different silicon atom.
Advantageously, the organohydrogenopolysiloxane compound B is an organopolysiloxane comprising:
(i) at least two siloxyl units and, preferably, at least three siloxyl units of the following formula:
in which:
(ii) optionally at least one siloxyl unit of the following formula:
in which:
The organohydrogenopolysiloxane compound B can be formed solely of siloxyl units of formula (B.1) or in addition comprise units of formula (B.2). It can have a linear, branched, or cyclical structure. The degree of polymerisation is preferably greater than or equal to 2. More generally, it is less than 5000.
Examples of siloxyl units of formula (B.1) are in particular the following units: H(CH3)2SiO1/2, HCH3SiO2/2 and H(C6H5)SiO2/2.
When it is a question of linear polymers, the latter are substantially constituted:
These linear organopolysiloxanes can be oils with a dynamic viscosity of about 1 to 100,000 mPa·s at 25° C., generally about 10 to 5000 mPa·s at 25° C., or gums that have a molecular weight of about 1,000,000 mPa·s or more at 25° C.
When entailing cyclical organopolysiloxanes, the latter are constituted of siloxyl “D” units of the following formulas Z22SiO2/2 and Z3HSiO2,2, which can be of the dialkylsiloxy or alkylarylsiloxy type or of Z3HSiO2/2 units only. They then have a viscosity of about 1 to 5000 mPa·s.
Examples of linear organohydrogenopolysiloxane compound B are: dimethylpolysiloxanes with hydrogenodimethylsilyl ends, dimethylhydrogenomethylpolysiloxanes with trimethylsilyl ends, dimethylhydrogenomethylpolysiloxanes with hydrogenodimethylsilyl ends, hydrogenomethylpolysiloxanes with trimethylsilyl ends, and cyclic hydrogenomethylpolysiloxanes.
For organohydrogenopolysiloxane compound B, particular preference is given to oligomers and polymers having the general formula (B.3):
in which:
Particularly suitable for the invention as an organohydrogenopolysiloxane compound B are the following compounds:
with a, b, c, d and e defined hereinbelow:
In particular, the organohydrogenopolysiloxane compound B suitable for the invention is the compound of formula S1, where a=0.
Preferably the organohydrogenopolysiloxane compound B has a mass content of SiH unit between 0.2 and 91%, preferably between 0.2 and 50%.
In the framework of the invention, the proportions of organopolysiloxane A and of organohydrogenopolysiloxane B are such that the molar ratio of the hydrogen atoms bonded to the silicon (Si—H) in the organohydrogenopolysiloxane B to the alkenyl radicals bonded to the silicon (Si—CH═CH2) in the organopolysiloxane A is between 0.2 and 20, preferably between 0.5 and 15, more preferably between 0.5 and 10 and even more preferably between 0.5 and 5.
In order to allow for the obtaining of material Y according to the invention, the composition X implements at least one catalyst C which is a complex corresponding to the following formula:
[Ni(L1)2]
in which:
Note that at least one portion of the inventive nature of the invention, holds to the clever and advantageous selection of the structure of the catalyst C.
According to another preferred embodiment of the invention, the ligand L′ is an anion derived from a compound of formula (1): R1COCHR2COR3 (1)
in which:
Advantageously, the compound of formula (I) is chosen from the group consisting of β-diketones: 2,4-pentanedione (acac); hexanedione-2,4; heptanedione-2,4; heptanedione-3,5; ethyl-3 pentanedione-2,4; methyl-5 hexanedione-2,4; octanedione-2,4; octanedione-3,5; dimethyl-5,5 hexanedione-2,4; methyl-6 heptanedione-2,4; dimethyl-2,2 nonanedione-3,5; dimethyl-2,6 heptanedione-3,5; 2-acetylcyclohexanone (Cy-acac); 2,2,6,6-tetramethyl-3,5-heptanedione (TMHD); 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (F-acac)]; benzoylacetone; dibenzoyl-methane; 3-methyl-2,4-pentadione; 3-acetyl-pentane-2-one; 3-acetyl-2-hexanone; 3-acetyl-2-heptanone; 3-acetyl-5-methyl-2-hexanone; benzoylstearoylmethane; benzoylpalmitoylmethane; octanoylbenzoylmethane; 4-t-butyl-4′-methoxy-dibenzoylmethane; 4,4′-dimethoxy-dibenzoylmethane and 4,4′di-tert-butyl-dibenzoylmethane, and preferably from β-diketones 2,4-pentanedione (acac) and 2,2,6,6-tetramethyl-3,5-heptanedione (TMHD).
According to another preferred embodiment of the invention, the ligand β-dicarbonylato L1 is a β-ketoesterato anion chosen from the group consisting of anions derived from the following compounds: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tertiobutyl, isopentyl, n-hexyl, n-octyl, methyl-1 heptyl, n-nonyl, n-decyl and n-dodecyl esters of acetoacetic acid or those described in patent application FR-A-1435882.
According to a particularly preferred embodiment, the catalyst C is chosen from the complexes [Ni(acac)2], [Ni(TMHD)2], [Ni(ketoester)2] and [Ni(Rhodiastab 50)2]. It is understood that in the formulas hereinabove “acac” means the anion derived from the compound 2,4-pentanedione, “THMD” means the anion derived from the compound 2,2,6,6-tetramethyl-3,5-heptanedione, “ketoester” means the anion derived from a methyl ester of acetoacetic acid and “Rhodiastab 50” means a mixture of anions derived from the compound benzoylstearoylmethane, and of anions derived from the compound benzoylpalmitoylmethane.
The catalyst C can in particular be present in the composition X according to the invention in a content ranging from 0.001 to 10% molar of nickel per number of moles of C2-C6 alkenyl radicals bonded to silicon atoms of the organopolysiloxane compound A, preferably between 0.01 to 7%, and more preferably between 0.1 to 5%.
The composition X implemented in order to obtain the material Y according to the invention is preferably free of a catalyst based on platinum, palladium, ruthenium or rhodium. By the term “free” of a catalyst other than the catalyst C, it is understood that the composition X according to the invention comprises less than 0.1% by weight of catalyst other than the catalyst C, preferably less than 0.01% by weight, and more preferably less than 0.001% by weight, in relation to the total weight of the composition.
The composition X can advantageously include at least one adhesion promoter D.
Without limitation, it can be considered that the adhesion promoter D comprises:
M being chosen from the group formed by: Ti, Zr, Ge, Li, Mn, Fe, Al and Mg or mixtures thereof
In accordance with a preferred embodiment of the invention, the alkoxy organosilane (D.1) of the adhesion promoter D is selected from the products of the following general formula:
formula in which:
Without limitation, it can be considered that the vinyltrimethoxysilane is a particularly suitable compound (D.1).
Regarding the organosilicon compound (D.2), it is provided in accordance with the invention, to choose it:
a) either from the products (D.2a) having the following general formula:
formula in which:
with:
b) or from the products (D.2b) constituted of epoxyfunctional polydiorganosiloxanes comprising:
(i) at least one siloxyl unit of formula:
formula in which:
and (ii) optionally at least one siloxyl unit of formula:
formula in which G has the same meaning as hereinabove and r is equal to 0, 1, 2 or 3.
With regards to the last compound (D.3) of the adhesion promoter D, the preferred products are those of which the metal M of the chelate and/or of the alkoxide (D.3) is chosen from the following list: Ti, Zr, Ge, Li or Mn. It is to be underlined that titanium is more particularly preferred. It can be combined, for example, with an alkoxy radical of the butoxy type.
The adhesion promoter D can be formed from:
Or according to two preferred embodiments from:
and finally according to the most preferred embodiment: (D.1)+(D.2)+(D.3).
According to the invention, an advantageous combination for forming the adhesion promoter is the following:
From a quantitative standpoint, it may be stated that the proportions by weight between (D.1), (D.2) and (D.3), expressed as a percentage by weight in relation to the total of the three, are the following:
with the understanding that the sum of these proportions in (D.1), (D.2) and (D.3) is equal to 100%.
For better adhesive properties, the weight ratio (D.2):(D.1) is preferably between 2:1 and 0.5:1, with the ratio 1:1 being more particularly preferred.
Advantageously, the adhesion promoter D is present at a rate of 0.1 to 10% by weight, preferably 0.5 to 5% by weight, and more preferably between 1 to 3% by weight, in relation to the total weight of all of the constituents of the composition X.
According to a particular embodiment, the composition X implemented in order to obtain the material Y according to the invention also comprises at least one charge E.
The charges E optionally contained in the compositions according to the invention are preferably mineral. They can in particular be siliceous. Being siliceous materials, they can play the role of a reinforcing or semi-reinforcing charge. The siliceous reinforcing charges are chosen from colloidal silicas, silica powder for combustion and precipitation or mixtures thereof. These powders have an average particle size generally less than 0.1 μm (micrometres) and a BET specific surface area greater than 30 m2/g, preferably between 30 and 350 m2/g. The siliceous semi-reinforcing charges such as diatomaceous or crushed quartz earth, can also be used. With regards to non-siliceous mineral materials, they can intervene as a semi-reinforcing mineral charge or filler. Examples of these non-siliceous charges that can be used alone or in a mixture are carbon black, titanium dioxide, aluminium oxide, alumina hydrate, expanded vermiculite, unexpanded vermiculite, calcium carbonate optionally with a fatty acid surface treatment, zinc oxide, mica, talc, iron oxide, barium sulphate and slaked lime. These charges have a granulometry that is generally between 0.001 and 300 μm (micrometres) and a BET surface less than 100 m2/g. In a practical but not limiting way, the charges used can be a mixture of quartz and of silica. The charges can be treated with any suitable product. From a weight standpoint, it is preferred to implement a quantity of charge between 1% and 50% by weight, preferably between 1% and 40% by weight in relation to all of the constituents of the composition.
The invention as such also has for object, in the framework of this application, a crosslinkable composition X comprising:
[Ni(L1)2]
in which:
The composition X according to the invention can furthermore include one or several usual functional additives. As families of usual functional additives, mention can be made of:
Silicon resins are branched organopolysiloxane oligomers or polymers that are well known and available off the shelf. They have, in their structure, at least two different units chosen from those of formula R3SiO1/2 (M unit), R2SiO2/2 (D unit), RSiO3/2 (T unit) and SiO4/2 (Q unit), with at least one of these units being a T or Q unit.
The radicals R are identical or different and are chosen from C1-C6 linear or branched alkyl, hydroxyl, phenyl, trifluoro-3,3,3 propyl radicals. As alkyl radicals, mention can for example be made of methyl, ethyl, isopropyl, tertiobutyl and n-hexyl radicals.
As examples of branched organopolysiloxane oligomers or polymers, mention can be made of MQ resins, MDQ resins, TD resins and MDT resins, the hydroxyl functions can be carried by the M, D and/or T units. As an example of resins that are particularly well suited, mentioned can be made of hydroxyl MDQ resins that have their weight content in hydroxyl group between 0.2 and 10% by weight.
The materials Y according to the invention can in particular be obtained by introducing initially the catalyst C into the reaction medium, then by adding the organopolysiloxane A under stirring. Finally, the organohydrogenopolysiloxane compound B is introduced and the temperature of the mixture is increased in order to reach the crosslinking temperature. The mixture is maintained at the crosslinking temperature until the stopping of the stirring due to an increase in the viscosity of the mixture.
This invention also has for object a silicone composition crosslinking method, characterised in that it consists in heating the composition X such as defined hereinabove to a temperature of between 70 and 200° C., preferably between 80 and 150° C., and more preferably between 80 and 130° C.
The composition X implemented in order to obtain the material Y according to the invention has the advantage of not being sensitive to air and of being able as such to be implemented and in particular crosslink under a non-inert atmosphere, and in particular in air.
This invention is shown in detail in the non-limiting embodiments.
1) Constituents
1) Organopolysiloxane A: divinyltetramethylsiloxane (dvtms) (1.073 mole of vinyl radicals bonded to the silicon for 100 g of oil)
2) Organohydrogenopolysiloxane B of formula: MD′50M (1.58 mole of hydrogen atoms bonded to the silicon for 100 g of oil), with: M: (CH3)3SiO1/2; and D′: (CH3)HSiO2/2
3) Catalysts (A), (B), (C), (D), (E) and (F):
The catalysts (A), (B), (C) and (D) are available off the shelf, for example under the references Strem purity >95% for the compound [Ni(acac)2], Strem purity >98% for the compound [Ni(TMHD)2].
The catalyst (E) is obtained via a synthesis that is well known to those skilled in the art:
The ketoester compound with R1=Methyl and R2=Methoxy (supplier: Sigma-Aldrich) is in a first step deprotonated using an equivalent of Bu-Li (supplier: Sigma-Aldrich) at low temperature (−78° C.). The salt obtained is re-crystallised in diethylether. The obtained deprotonated ligand (lithium salt) is added to a nickel chloride (NiCl2) in solution in the THF at ambient temperature (12 h). After decantation, filtration and concentration, the complex is re-crystallised in the THF.
The complex [Ni(ketoester)2] has the form of a green apple solid.
The catalyst (F) is also obtained by synthesis well known to those skilled in the art:
The diketone compound with R1=Phenyl and R2═C17H35 or C15H31 (supplier: Solvay) is in a first step deprotonated using an equivalent of Bu-Li (Supplier: Sigma-Aldrich) at low temperature (−78° C.). The salt obtained is re-crystallised in the diethylether. The obtained deprotonated ligand (lithium salt) is added to a nickel chloride (NiCl2) in solution in the THF at ambient temperature (12 h). The complex obtained is viscous, with a green coloration. A step of re-crystallisation makes it possible to lead to the obtaining of a solid.
II) Formulations and Results:
For each formulation tested, the catalyst is weighed and introduced into a Schlenk at ambient temperature and under inert atmosphere when the complex is sensitive to air (case in particular with Ni(0)), or into a glass flask when the complexes are stable in air.
1.87 g of divinyltetramethylsiloxane (dvtms) then 1.27 g of oil MD′50M are then introduced. The flask (or Schlenk) is placed under stirring in an oil bath that will be heated to the desired reaction temperature.
The ratio R corresponds to the molar ratio of the hydrogen atoms bonded to the silicon (Si—H) in the organohydrogenopolysiloxane (MD′50M) to the alkenyl radicals (here vinyl) bonded to the silicon (Si—CH═CH2) in the organopolysiloxane (dvtms).
The start of crosslinking is measured. The start of crosslinking is defined as being the stopping of the stirring due to an increase in the viscosity of the medium.
(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH2) in dvtms
The comparative formulation 1 comprising a complex of Ni(0) crosslinks after 3h20 but must be maintained under inert atmosphere. Indeed, under a non-inert atmosphere, the complex breaks down very quickly, even before the start of the reaction, during the rise in temperature.
The formulations 2 and 4 according to the invention where the catalyst is a complex of Ni(II) having two β-dicarbonyl ligands crosslink in 1 to 2 h.
The comparative formulation 3, implementing a complex of Ni(II) having stearate ligands, crosslinks only after 45 h.
Furthermore the nickel catalysts according to the invention were tested in the following different operating conditions:
(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH2) in dvtms
The formulations 5 and 6 according to the invention show that a crosslinking is obtained at 90° C., even if this crosslinking is slower than that observed for formulations 2 and 4 carried out at 110° C.
The formulations 7, 8 and 10 according to the invention show that a crosslinking is obtained at 0.125% molar of catalyst, even if this crosslinking is slower than that observed for formulations 2, 4 and 9 comprising 0.25% molar of catalyst.
1) Organopolysiloxane A of formula MviD70M (0.038 mole of vinyl radicals bonded to the silicon for 100 g of oil), with: Vi=Vinyl; Mvi: (CH3)2ViSiO1/2 and D: (CH3)2SiO2/2
2) Organohydrogenopolysiloxane B of formula: MD′50M (1.58 mole of hydrogen atoms bonded to the silicon for 100 g of oil), with: M: (CH3)3SiO1/2; and D′: (CH3)HSiO2/2
3) Catalysts (A), (B), (C), (D), (E) and (F) such as defined in example 1.
II) Formulations and results:
For each formulation tested, the catalyst is weighed and introduced into a Schlenk at ambient temperature and under inert atmosphere when the complex is sensitive to air (case with Ni(0)), or into a glass flask when the complexes are stable in air.
Oil MviD70Mv1 then oil MD′50M were then introduced.
For a ratio R corresponding to the molar ratio of the hydrogen atoms bonded to the silicon (Si—H) in the organohydrogenopolysiloxane (MD′50M) to the alkenyl radicals (here vinyl) bonded to the silicon (Si—CH═CH2) in the organopolysiloxane (MviD70Mvi) of 1:1, 4.39 g of oil MviD70Mvi then 0.105 g of oil MD′50M were introduced.
The content in oil MviD70Mvi and in oil MD′50M were adjusted according to the ratio R desired.
The flask (or Schlenk) is placed under stirring in an oil bath that will be heated to the desired reaction temperature.
The ratio R corresponds to the molar ratio of the hydrogen atoms bonded to the silicon (Si—H) in the organohydrogenopolysiloxane (MD′50M) to the alkenyl radicals (here vinyl) bonded to the silicon (Si—CH═CH2) in the organopolysiloxane (MviD70Mvi).
The start of crosslinking is measured.
Study of the Duration of Crosslinking
(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH2) in the organopolysiloxane (MviD70Mvi)
The formulation 11 comprising a complex of Ni(0) crosslinks after 2h50 but must be maintained under inert atmosphere. Indeed, as already indicated in example 1, the complex breaks down very quickly under a non-inert atmosphere, even before the start of the reaction.
The formulations 12 and 14 according to the invention where the catalyst is a complex of Ni(II) having two β-dicarbonyl ligands crosslink after about 1h50 to 2h20.
The comparative formulation 13, implementing a complex of Ni(II) having stearate ligands, still does not crosslink after 48 h.
Furthermore the catalysts (E) and (F) according to the invention were tested in the following different operating conditions:
(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH2) in the organopolysiloxane (MviD70Mvi)
Study of the Effect of the Temperature
(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH2) in the organopolysiloxane (MviD70Mvi)
(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH2) in the organopolysiloxane (MviD70Mvi)
The formulations 18 to 23 according to the invention show that the increase in temperature makes it possible to significantly reduce crosslinking time.
Study of the Effect of the Concentration in Catalyst
(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH2) in the organopolysiloxane (MviD70Mvi)
(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH2) in the organopolysiloxane (MviD70Mvi)
The formulations 12, 19 and 24 to 29 according to the invention show that the increase in the concentration of catalyst makes it possible to significantly reduce crosslinking time. The formulation 25 further shows that the crosslinking can be observed even with very low catalyst contents, which makes it possible to prevent or limit the coloration of the crosslinked material.
Study of the Effect of the Ratio R
(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH2) in the organopolysiloxane (MviD70Mvi)
(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH2) in the organopolysiloxane (MviD70Mvi)
The crosslinkings are carried out under a non-inert atmosphere. The formulations 14 and 14A, and 30 and 31 show that the increase in the ratio R makes it possible to reduce crosslinking time.
Duration of Crosslinking of Catalysts (A), (B), (E) and (F)
Finally, the crosslinking for the catalysts (A), (B), (E) and (F) was tested with a ratio R of 1.6:1. The results are presented in table 8.
(1)Expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH2) in the organopolysiloxane (MviD70Mvi)
The crosslinkings are carried out under a non-inert atmosphere. The formulations 32 to 35 show that the crosslinking is observed for different nickel based catalysts at the degree of oxidation (II).
1) Organopolysiloxane A of formula MviD350Mvi, with: Vi=Vinyl; Mvi: (CH3)2ViSiO1/2 and D: (CH3)2SiO2/2
2) Organohydrogenopolysiloxane B of formula: MD′50M (1.58 mole of hydrogen atoms bonded to the silicon for 100 g of oil), with: M: (CH3)3SiO1/2; and D′: (CH3)HSiO2/2
3) Catalyst (A) such as defined in the example 1.
We weighed 12.4 g of MviD350Mvi with: Vi=Vinyl; Mvi: (CH3)2ViSiO1/2 and D: (CH3)2SiO2/2 and 0.6 g of MD′50M (1.58 mole of hydrogen atoms bonded to the silicon for 100 g of oil), with:
M: (CH3)3SiO1/2; and D′: (CH3)HSiO2/2
The ratio R corresponding to the molar ratio of the hydrogen atoms bonded to the silicon (Si—H) in the organohydrogenopolysiloxane (MD′50M) on the alkenyl radicals (here vinyl) bonded to the silicon (Si—CH═CH2) in the organopolysiloxane (MviD350Mvi) of 10:1.
5 mol % of catalyst [Ni(TMHD)2] (expressed as a molar % of nickel per number of moles of vinyl radicals bonded to the silicon (Si—CH═CH2) in the organopolysiloxane (MviD350Mvi)) is dissolved at ambient temperature in the oil MD′50M and the mixture is incorporated at ambient temperature in the oil MviD350Mvi. The whole is placed in a Teflon mould then into an oven at 110° C.
After two hours, the crosslinked material is demoulded and its hardness (in Shore A) measured. The material has a hardness of 9 in Shore A degrees.
This example makes it possible to show that the implementing of catalysts claimed in crosslinking reactions of organopolysiloxane compound A with an organohydrogenopolysiloxane compound B allows for the obtaining of materials Y of which the hardness can be measured.
Number | Date | Country | Kind |
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14 60803 | Nov 2014 | FR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/FR2015/053012 | 11/6/2015 | WO | 00 |