NZ210695A - Polyorganosiloxane compositions containing chelated-tin crosslinking catalyst - Google Patents

Abstract

1. Polyorganosiloxane composition curable to give an elastomer, characterized in that it contains polydiorganosiloxanes carrying condensable or hydrolyzable groups at the end of the chain, and, if appropriate, silicon compounds of which each molecule carries at least three condensable or hydrolyzable groups, and a catalytically effective quantity of a tin (IV) chelate, from 0.001 to 10 parts by weight per 100 parts of polydiorganosiloxanes.

Description

New Zealand Paient Spedficaiion for Paient Number £10695 Priority D: L. v.-viTipIetB i_ciiication Filed ■.«: ..foiusyo^.

C&SSTJ/tt* C°&K5/57;. .C?tt.3Ai' 3 0 MAY 1988) vjos.

Date: 'jd: NO DRAWINGS NEW ZEALAND 21 DEC 1984 | + i! 270695 N/3B71B PATENTS ACT 1933 PATENTS FORM No. 5 COMPLETE SPECIFICATION POLYORGANOSILOXANE COMPOSITION CONTAINING A CHELATED TIN CATALYST WHICH CURES TO GIVE AN ELASTOMER WE, RHONE -POUL E NC SPECIALITES CHIMIQUES, a French Body Corporate, (France) "Les Miroirs", 18, avenue d'Alsace, 92400 Courbevoie, France, hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: -1- (followed by page la) 210G95 1*- | I The present invention relates to polyorganosiloxane compositions which cure to give an elastomer and contain a tincatalyst. j Numerous tin compounds have been proposed as j $ crosslinking catalysts for polyorganosiloxane compositions j and in particular for RTV compositions (room temperature vulcanizable compositions) in one or two packs, otherwise called one-component or two-component compositions.

The most widely used compounds are tin carboxylates, such as tributyltin monooleate and tin 2-ethylhexanoate, and. dialkyltin dicarboxylates such as dibutyltin dilaurate and dibutyltin diacetate (see Noll, "Chemistry and technology of silicones", page 337, Academic Press, 1968 - 2nd edition).

The tin catalyst proposed in U.S. Patent 3,186,963 15 is the reaction product of a tin salt, in particular dibutyltin dilaurate, with polyethyl silicate.

The tin catalyst proposed in U.S. Patent 3,862,919 is the reaction product of a dia Iky1dia 1koxysi1ane with a tin carboxylate.

It has also been proposed to use as a catalyst the reaction product of an alkyl silicate or an alkyl-trialkoxysilane with dibutylin diacetate.

Titanium chelates have been described as polymerization catalysts for ' organopolysiloxane compositions, which cure to give ' c 13 APR Bo 210695 - i - j elastomers, and it has been suggested that the titanium can be j { replaced with any one of 18 other metals amongst which tin I \ is mentioned but no other information concerning these 18 ! I metals has been provided and, in particular, no indication { I wasgiven of what valency and coordination number of these | metals could be used. | i Chemical Abstracts, volume 98, no. 8, 21st February j 1983, page 34, number 549 842, summarizes a Russian publication describing the use of a tetracoordinate tin (II) chelate for crosslinking polymethylphenylsiloxane to manufacture silicone resins but not elastomers.

The tin catalysts of the prior art are admittedly effective, but they have certain disadvantages. Thus, they are frequently toxic or, in the case of the stannosiloxanes, expensive and difficult to prepare. Furthermore, these [ | products are sometimes very active and can therefore be used j only with great difficulty, if at all, in one-component polyorganosiloxane compositions. In addition, the cured elastomers very often have a poor reversion stability.

There is therefore a need for a tin catalyst which is soluble in polysiloxanes, of low toxicity and low cost, and easy to prepare, and which can be used both in one- I component and two-component polyorganosiloxane compositions which cure to give elastomers having a good reversion stability, i.e. : a catalyst which is relatively inactive in the absence of. ' : ' ■ ! 13 APR 1988 i -1 3 atmospheric moisture or at ambient temperature, but which is active in the presence of moisture or simply on mixing the two components. type. According to the present invention, a polyorganosiloxane composition capable of being cured to give an elastomer, comprises a polydiorganosiloxane carrying condensable or hydrolyzable groups at the end of the polymer chain, a catalytical1y effective quantity of a tin(IV) 10 chelate, preferably a hexacoordinate tin(IV) chelate, and, optionally, a silicon compound in which each molecule carries at least 3 condensable or hydrolyzable groups. more particularly to those which are liquid at ambient 15 temperature and pressure, because they are very soluble in silicones. More particularly, these chelates preferably correspond to the formula: The present invention provides a catalyst of this Among these tin(IV) chelates, preference is given §> - ■."J** - A - 210695 0 (I) in which: the radicals and which are identical or different/. represent a C^-C^ alkyl radical, a C^-C^ alkoxy radical, a C.J-C.J2 alkenyl radical, a C-j-C^ ac YI radical, a C^-C^ acyloxy radical, an optionally halogenated C_-C0 cyclo- o alkyl radical, an optionally halogenated mononuclear aryl radical, a mononuclear alkyl aryl radical of which the alkyl part is or an optionally halogenated mononuclear arylalkyl radical of which the alkyl part is C^_4, Cj_-C12 alkyl radical being preferred.

Rj and R^, which are identical or different, are chosen from the hydrogen atom and a radical containing not more than about 8 carbon atoms and chosen from alkyl radicals, halogenoa I ky I radicals, cyanoalkyl radicals, alkoxy radicals, halogenoaIkoxy radicals, cyanoalkoxy radicals, optionally halogenated mononuclear aryl radicals and optionally halogenated mononuclear arylalkyl radicals of which the alkyl part is C, - C . ; and 1 u R^ is chosen from the hydrogen atom and a radical con--, taining not more than about 8 carbon atoms and chosen I ~ 13 APR '>33 . _ _ _ -, . ' 2 10695 from an alkyl radical, a ha logenoa I ky I radical and an aryl radical, or alternatively R^ and together form a cyclic hydrocarbon radical containing not more than 12 carbon atoms and optionally substituted by chloro, nitro 5 and cyano radicals.

The tin chelates according to the invention are known products whose preparation is described, for example, in U.S. Patent 3,055,845, which is cited as a reference in the present description. 10 The catalysts according to the invention can thus be prepared by transesterifying a product of the formula <A^) or (A 2: R1.

SnC0CH3)2 C A ^) ^/Sn(0C2H5>2 (Aj) R2 in which R ^ and have the same meanings as above, with 15 an appropriate chelating agent, methanol or ethanol being released.

The products of the formula (A ^ ) and their preparation are described in U.S. Patent 2,727,917.

A process for the preparation of the products of 20 the formula (I) from the products of the formula (A^) is described in J. OrganometaI. Chem., 4 (1965), pages 237-240, which is cited as a reference.

Another process consists in reacting a product of the formu la (B): Sn<halogen>2 (B) R 2 in which R^ and R^ have the same meanings as above, with the appropriate chelating agent, the hydrogen halide formed being removed.

Another process consists in reacting a tin oxide of the fo rmu la ( C ) : in which R^ and have the same meanings as above, with the appropriate chelating agent, the water formed being removed. the formula (I) from the products of the formula (C) is described in Journal of the American Chemical Society 87:9, 5th May 1965, pages 1909-1916, which is cited as a reference. tioned the methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, secondary butyl, tertiary butyl, amyl, hexyl, heptyl and octyl radicals, as alkenyl radicals the vinyl a I I y I, n-but-1-enyl and n-pent-2-eny I radicals, as alkoxy radicals the methoxy and ethoxy radicals, as acyl oxy radicals the formyloxy, acetoxy and propionyloxy radicals, as optionally halogenated cycloalkyl radicals 0 CC) A process for the manufacture of the products of As alkyl radicals R^ and R2, there may be men- the eye I open t yI, cyclohexyl, cycloheptyl, cyclooctyl, 3,4-dichIorocycI ohexyI and 2,6-dibromocyc I ohepty I radicals, and as optionally halogenated mononuclear aryl radicals the arylalkyl or alkylaryl radicals, the 5 phenyl, benzyl, tolyl, xylyl, 2,6-dichI 0ropheny I , 4- bromophenyl, 2,5-dif luoropheny I , 2,5-dibromopheny I and 2,4,6-tri chlorophenyl radicals.

The alkyl, alkoxy, aryl and arylalkyl radicals Rj and Rj can be the same as and R^. As haLogenoa I ky I 10 radicals Rj and Rj, there may be mentioned the chloro-methyl, trichIoromethy I, iodomethyl, f I uoromethy I , tri-f I uoromethy I , chloroethyl, ch I oro-n-propy I , bromo-n-propy I and 2,4-dichIoroocty I radicals, as cyanoalkyl radicals the cyanomethyl, beta-cyanoethy I and gamma-cyanopropy I 15 radicals, as cyanoalkoxy radicals the cyanomethoxy, beta-cyanoethoxy and gamma-cya nopropoxy radicals, and as halogenoa I koxy radicals the chIoromethoxy, iodoethoxy, trichloromethoxy, dich loroethoxy and 2,3-dichIoropentoxy radicals.

The aLkyL and ha Iogenoa I ky I radicals R^ can be the same as the radicals and R,., and as the acyl radical R^, there may be mentioned the formyl, acetyl and propanoyl radicals.

The following products may be mentioned as 25 examples of hex acoordinate tin(IV) chelates: -C H. 2 40695 nC4V nC4H9 ;sn o = c: *C H •0 C, (1 ) ■CH. nC8H17, nC8H17 ,0 = c; '0 — c.

.CH.

CH "CH. (2) nC4H9- nC4H9 .o = c: so—c. .o-C2H5 'CH VCH. (3) 21069 S V nC4H9. nC4H9 -o = c; •o—c .CH2CHCCH3>2 *CH o (4) nC4H9. nC4H9 -0 = ct •0—c .CH.

"C H O (5) (6) C8H17" C8H17 :sn "I -CH. -o = c: ■o—c "CH o (7) r 2 i 0 6 95 0 = c 0 — c CH2CH(CHJ>2 o • (8) 1 (9) The products of the formulae (1) to (9) above are all Liquid and perfectly soluble in the polysiloxane compositions.

The po I ydiorganosi Ioxanes which can be used in the compositions according to the invention are more particularly those corresponding to the formula (II): Y S i R, 0(S i R-,0) S i R, Y (II) n 3-n 2 x 3-n n in which: R represents identical or different monovalent hydrocarbon radicals, which can be polymers and/or carriers of sub-stituents, Y represents identical or different hydrolyzable or condensable groups or hydroxyl groups, n is chosen from 1,2 and 3 and x is an integer greater than 1.

The viscosity of the polymers of the formula (II) is between 50 and 10^ mPa.s at 25°C. Examples of radicals R which may be mentioned are alkyl radicals having from 1 to 8 carbon atoms, such as methyl, ethyl, propyl, butyl, hexyl and octyl, alkenyl radicals having from 1 to 4 carbon atoms, such as vinyl, allyl, ethylallyl and butadienyl, and mononuclear aryl radicals such as the phenyl, benzyl and tolyl radicals. Examples of substituted radicals R which may be mentioned are the 3,3,3-1rifIuoropropyI, chlorophenyl and beta-cyanoethyI radicals.

Examples which may be mentioned of optionally substituted polymeric radicals R are polymers or copolymers joined to the silicon by an Si-C bond and derived from at least one monomer po I ymerizab1e through the presence of an ethylenic unsaturation, such as styrene, vinyl acetate, n-butyl acrylate, n-butyl meth-acrylate and acry I onitriIe.

In the products of the formula (II) which are generally used in industry, at least 60% of the radicals R are methyl radicals, the other radicals generally being phenyl and/or vinyl radicals.

Examples which may be mentioned of hydrolyzable groups Y are the amino, acylamino, aminoxy, ketiminoxy, iminoxy, alkoxy, a I koxya Iky I eneoxy, acyloxy and phosphato groups.

As amino groups Y, there may be mentioned the n- 210695 12 - buty lamino, sec.-buty lamino and cyc lohexylamino groups, 5 f ? as examples of acylamino groups, there may be mentioned I | the benzoylamino group, as examples of aminoxy groups the j dimethy I aminoxy, diethy I aminoxy, dioctyI ami noxy and di- j t pheny I a m i no x y groups, and as iminoxy and ketiminoxy groups j >• i ! Y acetophenone oxime, acetone oxime, benzophenone oxime, ! J methyl ethyl ketoxime, diisopropyl ketoxime and chloro- | i eyelohexanone oxime.

As alkoxy groups Y, there may be mentioned groups having from 1 to 8 carbon atoms, such as the nethoxy, j S ethoxy, propoxy, i sopropoxy, butoxy, hexyloxy and octyloxy j < groups, and as the alkoxyalkyLeneoxy group Y, there may be j mentioned the methoxyethyleneoxy group. ! i Acyloxy groups Y which may be nentioned are i i groups having from 1 to 8 carbon atoms, such as the formyl-oxy, acetoxy and propionyloxy groups. i Phosphato groups Y which may be mentioned are the dimethyl phosphate, diethyl phosphate and dibutyl phosphate groups.

Condensable groups Y which may be mentioned are the hydrogen atom and the halogen atoms, preferably chlorine.

When the groups Y are hydroxyl groups in the formula (II) above, in which case n is equal to 1, it is 25 necessary, in order to prepare polyorganosiloxane elastomers from the polymers of the formula (II) above which have condensable or hydrolyzable groups in their terminal 2 10695 units, to use, in addition to condensation catalysts, crosslinking agents of the general formula (III): R. S i Y ' (III) 4-a a in which R has the meanings given above for the formula 5 (II), Y ' represents identical or different hydrolyzable or condensable groups and a is equal to 3 or 4.

The examples given for the groups Y are applicable to the groups Y'.

The alpha,omega-dihydroxypolydiorganosiloxanes 10 of the formula (II) are generally oils whose viscosity varies from 500 mPa.s at 25°C to 500,000 mPa.s at 25°C, preferably from 800 mPa.s to 400,000 mPa.s at 25°C; they are linear polymers consisting essentially of diorgano-siloxy units of the formula (RgSiO). However, the 15 presence of other units such as RSiO^^^' RSiO^^ anc^ Si04/2, generally as impurities, is not excluded in a proportion of at most 1% relative to the number of di-organosiloxy units.

The organic radicals bonded to the silicon atoms 20 of the base oils and represented by the symbol R can be chosen from alkyl radicals having from 1 to 3 carbon atoms, such as the methyl, ethyl and n-propyl radicals, the vinyl radical, the phenyl radical, the 3,3,3-trif I uoro-propyl radical and the beta-cyanoethy I radical. 25 /\t least 60% of all the radicals R are methyl radicals and at most 1% are vinyl radicals.

The units of the following formulae may be men m 1 5 210695 tioned by way of illustration of units represented by the formula RgSiO: (CH3>2$iO, CH3(CH2=CH)Si0, CHj(C6H$)Si0, (C6H552Si0' CF3CH2CH2(CH3)SiO, NC-CHgCH2(CHj)$i0 and NC-CH2CH2(C6H5>SiO.

The large majority of these base oils are irar- keted by the silicone manufacturers. Furthermore, the techniques for their manufacture are well known. i r i Examples of monomeric silanes of the formula (III) j which may be mentioned more particularly are polyacyloxy- ? ! silanes, polyalkoxysilanes, polyketiminoxysilanes and j, po I yiminoxysi I anes, and in particular the following ! i silanes: CHjSi(0C0CH3)3, C2H$Si (0C0CHj)3, CH2=CHSi(0COCH3)3, C6H5Si(0C0CH3)3, CF3CH2CH2Si(0C0CH3)3, NC-CH2CH2Si(0C0CH3)3/ CH2ClSi(OCOCH2CH3)3, CH3Si(0N=C(CH3)C2H5)3, CH-jSi- j j (0N=CH-CH3>3, CH3Si(0N=C(CH3)C2H5)2OCH2CH2OCH3 and j CHjSi (0N = CH-CH3)2OCH2CH2OCH3. j The above silanes, in association with alpha, j i omega-dihydroxypolydiorganosiloxane.s of the formula (II), can be used in one-component compositions which are stable j in the absence of air. j As examples of monomeric silanes of the formula | i (III) which, in association with alpha,omega-dihydroxy-25 po I ydiorga nosi I oxanes of the formula (II), can advantageously be used in two-component compositions, there may be mentioned polyalkoxysilanes and in particular thoie ^ \ • '• p T? } Nf ? 2 10695 of the formulae: SiCOCgH^.)^, Si(O-n-CjH^)^, S i (0-i s oC Si(0C2H40CH3)4, CHjSi(OCHjJJ, CH2=CHSi(0CH3)3, CHjSi-(OCgH^OCHj)3, CH2ClSi(OC2H5>3 and CH2=CHSi(OCjH^OCHj)3.

All or part of the above monomeric silanes can be 5 replaced with po 1 yaIkoxypoIysiIoxanes of which each molecule contains at least two, preferably three, groups y* and/or at least two, preferably three, atoms Ythe other valencies of the silicon being satisfied by siloxane linkages SiO- and SiR. Polyethyl silicate may be men-10 tioned as an example of a poLymeric crosslinking agent.

The above two-component compositions containing a catalyst according to the invention have particularly advantageous properties, especially as regards the setting time and the reversion stability.

In general, from 0.1 to 20 parts by weight of crosslinking agent of the formula (III) are used per 100 parts by weight of polymer of the formula (II).

The polyorganosiloxane compositions of the type described above, which cure to give elastomers, contain 20 from 0.001 to 10 parts by weight, preferably from 0.05 to 3 parts by weight, of a preferably hexacoordi nate tin(IV) chelate per 100 parts by weight of polysiLoxane of the formula (II).

The proportion of tin catalyst in the one-25 component compositions is generally much lower than that used in the two-component compositions and is generally between 0.001 and 0.05 part by weight per 100 parts by 210G95 weight of po I ysiLoxane of the formula (II).

Whether they can be used to prepare the one-component or the two-component compositions, the cross- • w linking agents of the formula (III) are products available on the silicone market; furthermore, their use in compositions which cure at or above room temperature is known and is mentioned, for example in U.S.Patent 3,697,568.

The poIydiorganosiIoxane compositions which cure to give elastomers can also contain products commonly used to improve or modify the properties of the elastomers, especially the mechanical properties, in the desired direction. Examples of such products which may be mentioned are reinforcing, semi-reinforcing and non-reinforcing fillers such as pyrogenic silicas, precipitated silicas, pyrogenic titanium and aluminium oxides, carbon blacks, ground quartz, diatomaceous silicas, calcium carbonate, calcined clay, titanium oxide of the rutile type and the oxides of iron, zinc, magnesium and aluminium.

Pigments, dyestuffs, corrosion inhibitors, adhesion promoters, plasticizers and solvents may also be mentioned.

The compositions according to the invention can be used simply by mixing their constituents, it being possible, if appropriate, to introduce water at a sub-/\^11 ^ Q::. / v*« / X ' A sequent stage. These compositions can be used, for r example, for the casting of electrical and electronic '' 210695 components or engine components, for the manufacture of mouldings, for the taking of impressions, in particular dental impressions, for coverings, for insulations and for all the other applications which utilize this type of 5 composition curing to give an elastomer.

The following examples illustrate the invention.

Parts and percentages are by weight unless stated otherwise.

Example 1: Synthesis of dibutyltin bis(acetyl acetonate) (formula (1) above). 41 g (0.16 mol) of dibutyltin oxide corresponding to the formula (C) above are reacted with 130 ml (1.27 mol) of acetyl acetone in a three-necked round-bottomed flask by ! heating under reflux for 7 hours, the temperature of the j flask being kept at 110°C. A slight vacuum (15-20 mm Hg) is then applied to the flask to remove the excess acetylacetone. The product of the formula (1) is then present in the flask in the form of a pale yellow liquid. The infra-red and NMR spectra confirm the theoretical 20 structure of the molecule.

. .. ' ..JL.' ,. ... 2 10695 Example 2: Synthesis of dibutyltin bisCethylacetoacetate) (formula (3) above). 27.3 g, i.e. 0.21 mol, of ethyl acety I acetate are 5 run, at room temperature, into 29.4 g, i.e. 0.1 mol, of dibutyldimethoxytin corresponding to the formula (A^) above. The reaction mixture is stirred for 30 minutes under a vacuum of about 15 to 20 mm Hg while the temperature is raised to 70°C. This gives the product of the 10 formula (3) in the form of a sLightly viscous, pale yellow liquid. The infra-red and NMR spectra confirm the theoretical structure of the molecule.

By repeating the procedure of Example 1 or 2 and selecting the appropriate starting materials, it is 15 easily possible to synthesize the products of the formulae (2) and (4) to (9) indicated above. The infra-red and NMR spectra confirm the theoretical structures of the various molecules.

Example 3: A polysiloxane composition A is prepared by mi x i ng : 300 parts of an alpha,omega-dihydroxypolydimethylsiloxane oil having a viscosity of 60,000 mPa.s at 25°C, 300 parts of a dimethyIsiIoxane oil blocked at each end by 25 a trimethy I siIyI unit and having a viscosity of 20 mPa.s at 250 C, 390 parts of ground quartz having a particle size of ^ i y Q between 0.5 and 10 microns, and 400 ppm of water.

The following are added to 100 g of composition A: 0.8 g of polyethyl silicate as a crosslinking agent and 0.0165, 0.025 or 0.0377 g of tin metal introduced in the form of dibutyltin bis(acety I acetonate).

The compositions obtained are run into a cylindrical dish with a height of one centimetre and a cross-sectional diameter of one centimetre, and the setting time of the two test-pieces is measured as well as the initial Shore hardness A (ASTM Standard D 2240) at room temperature and the Shore hardness A after the test-piece has been kept at 120°C for several days, in order to assess the reversion stability. This hardness is measured on the surface and on the bottom of the test-piece.

The results obtained are collated in Table I below. Comparative Examples 4 and 5 The procedure is the same as in Example 3, except that the catalyst of the invention is replaced with a known catalyst, namely with dibutyltin dilaurate for Example 4 and with a stannosi Ioxane of the formula: Si-0-Sn-00CCH3 210C95 described in U.S. Patent 4,102,860, for Example 5.

The results obtained are collated in Table I below.

This table shows that, for comparable quantities of tin metal, the catalyst according to the invention gives a much shorter setting time and a much better reversion stability. 13 APR 1988 f, s.< -,,4, "J •>■ jL i table i Tin Catalyst Sn »etal in g p«r 100 9 Of A Srtttnf tia» Shore Hardness A initial days 1 at 120*C day» it 120*C days »t 12Q*C 40 days at 120*C 80 day! at 120*C Dibutylttn acetyl* acttonatf 0.0377 0.025 0.0165 »in 25 Bin 2 h 20 nin surface: 18 17 17 16 botio«: IS 1S 18 surface: H H bottom: 15 surface: 15 16 16 16 16 16 botton: 17 17 16 17 17 17 Oibutyltin tfiUurjtt 0.0377 0.025 2 h 25 «in Z h surface: 18 9 6 2 0 0 bottom: 16 9 6 2 0 0 surface: 17 11 6 3 botto«: 16 7 3 Bu SiO-SnOOCCM, i J Bu 4 0.0207 2 h AO «in surface: T6 16 13 8 bottom: 16 12 7 3 dibutyltin b*s(2,2-d»- •ethyloctoate) 0.025 7 h Surface: 16 H i bottom: 15 14 13 L 2 106 Examp I es 6 to 11; The procedure is the same as in Example 2, except that the catalyst of the formula (1) used in Example 3 is replaced respectively with the catalysts of the formulae (3), (4), <5), (7), (8) and (9), prepared by the processes described in Examples 1 and 2 above.

The results obtained are collated in Table II below.

I dm k Q y table ii Eiitlf Tin ttlilltl Sn attll (n Setting tiae Shore Hardness A 9 D*r 100 g Sf * initial days at 120*C flays at 120*C days at 120*C 40 days at 120*C 6 formula (3) 0.025 1 h 30 «in surface: 12 13 14 bottoa: 14 13 14 7 formula (4) 0.025 55 »1n surface: 16 16 16 bottoa: 16 16 16 « foraula (5) 0.025 1 h 05 a in surface: 14 13 14 13 bottoa: 14 14 13 9 forwli (7) 0.025 1 h 30 "in surface: 13 13 14 13 bottoa: 14 13 14 13 to foraula (S) 0.025 1 h 35 am surface: 12 13 13 11 bouoa: 14 14 14 13 11 foraula (9) 0.025 1 h 20 «in surface: 13 12 13 13 bottoa: 13 13 14 2 10695 Example 12: The procedure is the same as in Example 3, except that 1 g of ethyl silicate of the formula Si(0C~Hc), and c 3 H 0.05 g (weight of chelate) of dibutyltin bis(acetyl-5 acetonate) are added to 100 g of composition A.

The product obtained has a setting time of 15 minutes and a 2 mm thick place produced by moulding can be released from the mould in 30 minutes.

After 5 days, standardized test-pieces are taken 10 from plates and the following properties are measured: - Shore hardness A according to ASTM Standard D 2240 - tensile strength (TS) according to AFNOR Standard T 46002 corresponding to ASTM Standard D 412 - elongation at break (EB) in X according to AFNOR Stan-15 dard T 46002.

The following properties are found for the elastomer: Shore hardness A: 15 Tensile strength (TS): 1.35 MPa (megapascaIs) Elongation at break (EB): 250% Example 13: Preparation of a one-component elastomer vulcanizable in the cold.

A paste is prepared in the following manner: 25 The following are introduced into a malaxator: 100 parts of an a Ipha,omega-dihydroxydimethyLpo I y-siloxane oil having a viscosity of 80,000 mPa.s at 25°C, s•.. • . .

I * '"w 16 parts of a methy I po I ysiIoxane oil having a viscosity of 60 mPa.s at 25°C, having 0.9X of hydroxyl groups bonded to the silicon atoms, and consisting of (CH_),SiO_ J J U a 3 (CHj^SiO and CH^SiO^ ^ units distributed so as to give a 5 ratio (CHj)jSiO^ ^/(CHj^SiO of 0.04 and a ratio CH;jSi01 5/(CH3)2SiO of 0.4, and 14 parts of a pyrogenic silica having a specific surface area of 200 m2/g and treated with octamethyIcycIo-tetrasi loxane.

The whole is mixed at 150°C for 2 hours; during this operation, the atmosphere in the malaxator is swept with a stream of anhydrous nitrogen.

This paste is used to prepare 2 different compositions A) and B) : Composition A: parts of methy 11riacetoxysiIane and 0.015 part (in chelate form) of dibutyltin bis(acetyI acetonate) are added to 100 parts of the paste, cooled to about 60°C.

The whole is stirred for 1 hour and then placed in 20 sealed tubes in the absence of atmospheric moisture.

The elastomer obtained has the following properties: non-stick time (time taken to obtain a non-sticky feel) 10 mi nut es 25 after 5 days: tensile strength: 2.7 MPa elongation at break: 620% 2 i 0 o Shore hardness A: 17 Composition B: 8 parts of the crosslinking agent of the formula: CHjSi(ON=C(CHj)Cj)j and 0.1 part (in chelate form) of 5 dibutyltin bis(acety I acetonate) are added to 100 parts of the paste, cooled to about 60°C.

The whole is stirred for 1 hour and then placed in sealed tubes in the absence of atmospheric moisture.

The elastomer obtained has the following initial 10 propert i es: non-stick time: 40 minutes After 5 days: Shore hardness A: 18 tensile strength: 2.1 MPa 15 - elongation at break: 682% Accelerated ageing test: Composition B is placed in tubes impervious to atmospheric moisture; one tube is kept for 72 hours at 100°C. In all cases, the composition is easy to remove 20 from the tube into which it had been introduced, and it crosslinks when brought into contact with atmospheric moisture. This composition is used to produce plates for making test-pieces.

After 5 days, the properties of the elastomer obtained from the composition subjected to accelerated ageing are as follows: Shore hardness A: 16 _ 27 . 210G95 tensile strength: 1.6 MPa elongation at break: 630% This test shows that the composition subjected to accelerated ageing has virtually analogous mechanical propert i es. part of dimethylhydroxylamine. 9 parts of pyrogenic silica having a specific surface area of 300 m 2 / g and treated with octamethyl-cyclotetrasi loxane and 0.5 g (in chelate form) of dibutyltin bis(acetyI acetonate) are then added.

The compositions are kept in sealed tubes. 20 The elastomer obtained from these compositions has the following initial properties: non-stick time: 60 minutes After 5 days: tensile strength: 0.9 MPa 25 - elongation at break: 385% Ageing test The composition obtained is placed in sealed tjjbe^;4' <; Example 14: L. i t Preparation of a neutral one-component elastomer vulcanizable in the cold. 100 parts of an alpha,omega-dihydroxypo1ydi-methy I si loxane oil having a viscosity of 150,000 mPa.s at 25°C are treated with 8 parts of a crosslinking agent of the formula CHjSiCOC^C^OCH^)^ in the presence of 0.15 ? 13APR*988 I 2 10695 one of the tubes is heated at 100°C for 48 hours. In all cases, the composition is easy to remove from the tube into which it had been introduced, and it crosslinks when brought into contact with atmospheric moisture.

This composition is used to produce plates for making test-pieces.

After 5 days, the properties of t.he elastomer obtained from the composition subjected to accelerated ageing are as foLlows: tensile strength: 1.1 MPa elongation at break: 370% This test shows that the composition subjected to accelerated ageing at 100°C does not show any appreciable change in its mechanical properties.

Example 15: The procedure of Example 14 is repeated exactly, except that an oil having a viscosity of 20,000 mPa.s at 25°C is used as the a Ipha,omega-dihydroxypoIydimethy I -siloxane oil and a crosslinking agent of the formula Si(0CH,CH,0CH,). is used. 6 c. j h The non-stick time Ct) and the initial mechanical properties and the mechanical properties obtained in the accelerated ageing test are collated in Table III below (TS = tensile strength, EB = elongation at break).

Example 16: The procedure of Example 14 is repeated exactly, except that an oil having a viscosity of 20,000 mPa.s at 2 10 6 °C is used as the aIpha,omega-dihydroxypoLydimethyl-si loxane oil, the crosslinking agent being the same as that used in Example 14.

The properties obtained are collated in Table III below.

/ A y .

TABLE III Example t (i n m i n) Mechanical properties initial 48 h at 100°C TS (MPa) EB (%) TS (MPa) EB (%) 1 5 1 .4 225 1.15 245 1 6 60 0.85 385 1.1 370 o P u !U

Claims (12)

WHAT WE CLAIM IS:-

1. A polyorganosiloxane composition capable of being used to give an elastomer, comprising a polydiorganosiloxane carrying condensable or hydrolyzable groups at the end of the polymer chain, a catalytically effective quantity of a tin(IV) chelate, and, optionally, a silicon compound in which each molecule carries at least three condensable or hydrolyzable groups.

2. Composition according to Claim 1, in which the tin(IV) chelate is hexacoordinate.

3. Composition according to Claim 1 or 2, in which the said chelate is a liquid at ambient temperature and pressure.

4. Composition according to Claim 3, in which the tin catalyst corresponds to the formula: (I) 20 in which the radicals and R^, which are identical or different, each represent a C^-C^ alkyl radical, a C^-C^2 alkoxy radical, a sikenyl radical, a C^-C^ acyl Tadical, a C^-C^ acyloxy radical, an optionally halogenated C^-Cg cycloalkyl radical, an optionally halogenated mononuclear aryl radical, a mononuclear arylalkyl radical of which the alkyl part is C^-C^, or an 210G9^0 - 31 - optionally halogenated mononuclear alkylaryl radical of which the alkyl part is C^-C^, R^ and R^, which are identical or different, are each hydrogen or a radical containing no more than 8 carbon atoms and chosen 5 from alkyl, halogenoalkyl, cyanoalkyl, alkoxy, halogenoalkoxy, cyanoalkoxy, optionally halogenated mononuclear aryl and optionally halogenated mononuclear arylalkyl of which the alkyl part is C^-C^; and R^ is | hydrogen or a radical containing not more than 8 ^ 10 carbon atoms and chosen from alkyl, halogenoalkyl and aryl, or alternatively R ^ and R ^ together form a cyclic hydrocarbon radical containing not more than 12 < carbon atoms and optionally substituted by chlorine, I ' nitro or cyano. 15

5. Composition according to claim 4, in which R.j and R£ each represent a C^-C^ alkyl radical.

6. Composition according to any one of the preceding claims, in which the polydiorganosiloxane corresponds to the general formula: rv . V * 20 Yn5iR3-n0(SiR20)*SiR>-nVn (II) iSWI in which each R represents identical or different monovalent hydrocarbon radicals, which can be polymeric and/or carry substituents , each V represents identical or different hydrolyzable or condensable groups or 25 hydroxyl groups, n is 1 , 2 or 3 and x is an integer greater:-''1" ' f/.\ • O \ 13 APR 1988 ^ -^^^-^^.^iiKi'ii'WiiimDmminii. n. 21G395 r« j o: 3 •V"-' - 32 - than 1 .

7. Composition according to Claim 6 in which in the polydiorganosiloxane of the formula (II) n is 1 and Y is a hydroxyl group and which also contains a silicon 5 compound in which each molecule carries at least three condensable or hydrolyzable groups of the general formula: R,_aSiY'a (HI) in which R is as defined in claim 6 for formula (II), each Y* represents identical or different hydrolyzable or 10 condensable groups, and a is 3 or 4.

8. A composition according to Claim 7 in two-component form in which the silane of formula (III) is a polyalkoxysilane of which all or part can be replaced with a po1ya 1koxypo1ysi1oxane, and the quantity of 15 hexacoordinate tin (IV) chelate is 0.001 to 10 parts by weight, per 100 parts of polydiorganosiloxane of the formula (II).

9. A composition according to claim 8 in which the quantity of the said tin (IV) chelate is 0.05 to 3 20 parts by weight per 100 parts of the, said polydiorganosiloxane.

10. A composition according to Claim 7, in one-component form in which the silane of formula (III) is a polyacy1oxysi1ane , a polyalkoxysilane, a 25 polyketiminoxysilane or po1yiminoxysi1ane, and the quantity of hexacoordinate tin(IV) chelate is 0.001 to 0.05 part by' weight per 100 parts of polydiorganosiloxane of the formula (II). 13 APR 1988 WiSrr..*. <-.... v^-v .. . . _ „ „ ... ... 2 j 0 695 1 - 33 - t

11. A composition according to claim 1 substantially as described in any one of the foregoing Examples 3 and 6 to 16.

12- The product of curing a composition as claimed 5 in any of the preceding claims. OKTED Ti-USj^OAY OF %gSy- A.J C A K ». SON Pta c| ^ AGENTS t'Cvi the APPUGAKLB