GB2101150A

GB2101150A - Photopolymerisable liquid organopolysiloxane compositions for the coating of materials

Info

Publication number: GB2101150A
Application number: GB08217157A
Authority: GB
Inventors: Raymond Pigeon
Original assignee: Rhone Poulenc Specialites Chimiques
Current assignee: Rhone Poulenc Specialites Chimiques
Priority date: 1981-06-15
Filing date: 1982-06-14
Publication date: 1983-01-12
Also published as: IT1152971B; JPS5845259A; IT8221865A0; FR2507608B1; EP0070746A1; BE893506A; FR2507608A1; GB2101150B

Description

1

SPECIFICATION

Photopolymerisable liquid organopolysiloxane compositions for the coating of materials GB 2 101 150 A 1 The present invention relates to liquid organopolysiloxane compositions which can be photopolymerised by 5 ultraviolet radiation, which carry organic radicals containing aliphatically unsaturated groups chosen from amongst acryloyloxy, methacryloyloxy, acrylamido and methacrylamido groups, and which harden to give coatings having good mechanical properties and improved adhesion to a very wide variety of solids.

Liquid organopolysiloxane compositions which carry organic radicals containing aliphatically unsaturated groups, and which harden on exposure to ultraviolet radiation, have already been described and used. Some 10 of these compositions can be used for the preparation of coatings which are non-stick with respect to viscous and sticky materials. Such compositions consist, for example, of:

organopolysiloxane polymers which have a degree of polymerisation of more than 25 and which each carry at least one organic radical containing an acryloyloxy or methacryloyloxy group, this radical being joined to a silicon atom via a C-Si or C-O-Si linkage, (1) di-, tri- or tetra-acrylates or -methacrylates of polyols, or (2) low molecular weight organosilicon compounds which have from 1 to 25 silicon atoms and which contain from 2 to 6 acryloyloxy or methacryloyloxy groups, and photosensitisers (European Application No. A 6 705).

They can also consist of:

organopolysiloxane polymers formed of 0.5 to 100 mol % of organosiloxy units each carrying a vinyl group, the other organosiloxy units present carrying halogenated or unhalogenated hydrocarbon radicals free of aliphatic unsaturation, organohydrogenopolysiioxane polymers each carrying at least one hydrogen atom bonded to a silicon atom, the ratio of the Si-vinyl groups of the organopolysiloxane polymers to the SM groups of the organohydrogenopolysiloxane polymers being within the range 1/100 to 100/1, photosensitisers and if appropriate, organosilicon compounds containing mercapto groups, as hardening accelerators (French Applications 2,245,729 and 2,257,736).

Other compositions can be used forthe preparation of coatings of which the physical characteristics are 30 oriented particularly towards strength, solvent resistance and adhesion to substrates. These compositions are fairly similar to those mentioned above. Thus, they consist, for example, of:

organopolysiloxane polymers containing acryloyloxy or methacryloyloxy groups joined to the silicon atoms via divalent hydrocarbon radicals, photosensitisers and solvents (French Application 2,110,115).

They can also consist of:

organopolysiloxane polymers containing acryloyloxy or methacryloyloxy groups joined to the silicon atoms via divalent organic radicals formed of carbon, hydrogen, nitrogen and oxygen atoms, and photosensitisers (Japanese OPI Application 54-038,393, and German Application 3,006,167).

The coatings produced by the above compositions are intended to protect materials located in an aggressive environment. However, when these materials are subjected to numerous mechanical and/or thermal shocks, to deep stamping or to the prolonged action of solvents or adverse weather conditions, the deposited coatings do not lastingly retain their protective ability. As a result, the materials used under such conditions seriously affect or even stop (in particular in the field of electronic circuits) the operation of equipment into which they are introduced. It is therefore necessary to attempt to improve the properties of these coatings.

For this purpose, the present invention proposes photopolymerisable liquid organopolysiloxane compositions which lead to coatings possessing excellent mechanical properties and also very strong adhesion to the materials (of any nature) on which they are deposited. These coated materials can be employed in fields as varied as those of electronics, electrotechnics, building, metallurgy and the treatment of paper, cardboard, textiles and wood.

More precisely, the present invention provides photo polym erisa ble liquid organopolysiloxane compositions which have a viscosity ranging from 100 mPa.s at 2WC to 10,000 mPa.s at 25'C, and which are formed by mixing: A/ at least one monomeric or polymeric organosilicon compound carrying, bonded to its silicon atom or atoms:

1) at least one organic radical containing an unsaturated group of the formula C1-12=C(R)COQ-, in which the symbol R represents a hydrogen atom or the methyl radical and the symbol Q represents 0 or NH, and 2) at least one phenyl radical, the other organic radicals being chosen from the group comprising methyl, 60 ethyl, propyl, 3,3,3-trifluoropropyl and vinyl radicals, alkoxy radicals having from 1 to 5 carbon atoms, and P-metinoxyethoxy and hydroxyl radicals, B/ at least one organohydrogenopolysiloxane carrying, bonded to its silicon atoms, at least one hydrogen atom and at least one phenyl radical, the other radicals being methyl radicals, the compounds A and B being employed insufficient amounts to lead to a molar ratio of the groups SiH, 65 2 GB 2 101 150 A 2 provided bythe organohydrogenopolysiloxane B, to the groups C1-12=CIRCOQ-, provided bythe compound A, ranging from 0.5 to 7, C/ a photosensitiser chosen from amongst derivatives of benzoin, of xanthone or of thioxanthone, at a rate of 0.1 to 10 parts per 100 parts of components A and B together, and D! an organic diluent which is inert towards the compounds A, Band C, at a rate of 0 to 150 parts per 100 parts of components A and B together.

The organosilicon compound A can possess any number of silicon atoms and also have any structure, namely linear, branched, crosslinked or cyclic. It can be chosen from silanes, polysilanes, oily, gummy and resinous organopolysiloxanes, organosilicon polymers containing Si-T-Si and Si-OSi linkages (the symbol representing a divalent organic radical), and mixed organic/organopolysiloxane polymers formed, for example, by the reaction of organopolysiloxanes carrying hydrolysable groups with organic polymers (in particular polyesters, polyethers, polyepoxides, polyamides, polyurethanes, polyamines, polycarbonates and polyolefines) carrying groups capable of reacting with the hydrolysable groups.

Preferably, however, the compound A is chosen from amongstthe silanes of the general formulae:

H C(R)COQC(O) SiR, W, F 2 ' 1 b C -b-c G'OSiR' C F C11 2= C(R)COQGH2] b' C 3-c 2 in which: the symbols R and Q have the above meaning, the symbol G represents a divalent, linear or branched alkylene radical having from 1 to 5 carbon atoms, the symbol G' represents a trivalent or tetravalent, linear or branched alkyiene radical having from 1 to 5 carbon atoms, the symbol R' represents a methyl, ethyl, propyl, phenyl, vinyl or 3,3,3-trifluoropropyl radical, the symbol W represents an alkoxy radical having from 1 to 5 carbon atoms or a P-methoxyethoxy radical, the symbol a represents zero or 1, the symbol 25 b represents 1, 2 or 3 when a = 1, and only represents 1 when a = zero, the symbol c represents 1, 2 or 3, the symbol W represents 2 or 3, and at least one radical R' represents a phenyl radical.

Of divalent alkylene radicals having from 1 to 5 carbon atoms, represented by the symbol G, there may be mentioned those of the formulae:

-CH-z, -(CH2)-Z, -(CHA3-, -CH2CH(CH3)-, -CH2)W, -CH2-CH(CH,)CH2C1-12 Byway of illustration of trivalent ortetravalent alkylene radicals having from 1 to 5 carbon atoms, represented by the symbol G', there may be mentioned those of the formulae:

=CH-, =C-CH-7, =C(CH,)CH2 =C(CH2CH3)C1-12- Byway of illustration of alkoxy radicals having from 1 to 5 carbon atoms, represented bythe symbol W, there may be mentioned methoxy, ethoxy, n- propoxy, isopropoxy, n-butoxy, secAutoxy and n-pentoxy 40 radicals.

These silanes are frequently available on the chemical products market and can easily be manufactured in accordance with known techniques. Thus, the silanes of the formula:

r Sir, R" 1C112 C (R) CoGC)1 b c - bc F. 1 (derived from the formula F, in which a = 1 and b = 1, 2 or 3) can be prepared by reacting the unsaturated hydroxyl compounds of the formula C1- 12=C(R)COQG01-1 with silanes of the formula CibSiR'cR"4-b-,, the acid HCI being eliminated in the course of the reaction. 50 The silanes of the formula:

CH2=C(R)COQGSiR'cR"3-c F, (derived from the formula F, in which a = 0 and b = 1) can be prepared by reacting the unsaturated compounds of the formula C1-12=C(R)COQ1-1 or of the formula CH2=C(R)COWe (Me = alkali metal) with the 55 silanes of the formula XGSiR',R"3-, (X = Br, Cl), the acid XH or the salt XMe being eliminated in the course of the reaction.

The silanes of the formula F2 can be prepared by reacting the hydroxyl compounds of theformula [CH2=C(R)COQCH2]b,G'OH with the silanes of the formula C1SiW,,W3, or of the formula HSiR',R"3-,,, the acid HCI, or hydrogen, being eliminated in the course of the reaction; when hydrogen is evolved, the reaction is 60 facilitated by the presence of a catalyst (e.g. an amine, a metal derivative or a carboxylic acid salt of tin).

3 GB 2 101 150 A 3 Concrete examples of silanes represented bytheformulae F,, F, and F2, includethose corresponding to the following formulae:

cif 2. C(C11 3)COOCkt 2 CII 2 0Si(C 6 11 5) 2 CH 3 5 [H C(Cil)c0OCII CH Si(C H C 2= 3 2 1012 6 5 LCH 2. CIII-COOCII 2 C,1,] 2 Si(C 6 H 5)2 ICII 2= CHCOOCII 2 CH(CH 3)012 si(c 6 h' 5)(CH 3) CH 2. CIICOI9,1cil"G-Sic 6 P. 5 (CH 3), 10 ICIA 2_ C(CH 3)COOCH 2 CH 2613 sic 6 11 5 C112 =C(CH 3)COO(CH 2)3 Si(C 6 H 5)9c43 CH 2= Cdcoo(CH P3 Si(C 6 14 5),M-nC,13 9) CH 2= C(CH 3)CD.'IH(CH 2)3 sic 6 H 5 (OCH 3), 15 F F 2 L. 2= C(CH 3)COOCH 21 3 C-CH 2 Osi(c 6 H 5) (cli 3)12 (CH 2. CH-COOCII 2)2 CHOS i(C 6 H 5)2 CH 3 [Cif 2. C(C11 3)c0OCH 2] 2 C(Cti 2 CH 3) C.11 2 Osi(C 6 H P2 (O-IAC 3 H 7) 20 Preferably, the compound A is also chosen from linear or branched organopolysiloxane polymers which are liquid and have a viscosity of at most 30,000 mPa.s at 2WC, or those which are solid and have a melting point below 120'C. These polymers can be divided into 2 classes. The first class includes polymers of generally well-defined structure, which contain virtually no alkoxy and/or hydroxyl radicals bondedtothe silicon atoms.

They consist of:

1 to 100 mol % of units chosen from those of the formulae:

C11 2. C(R)COQC(O),SiM d 0 3-d 2 ICII 2 C(R)COQU2] bl C;IosiRld 0 3 2 d in which the symbols R, Q, R', G, G', a and W have the same meaning as that given above for the silanes of the formulae F, and F2, and the symbol cl represents 1 or 2, and 99 to 0 mol % of units of the formula WfSi04412 in which the symbol R' has the above meaning, the symbol f represents 1, 2 or3, the molar ratio (R'+ Z)/Si 40 ranges from 1.4 to 3, the symbol Z representing a radical of the general formula:

CH2=C(R)COW(O)-ff (CH2=C(R)COQCH2)b,G'O- and at least 5 mol %, preferably 10 mol %, of radicals Ware phenyl radicals.

These polymers are easyto prepare; they can be prepared, for example, starting from organopolysilox- anes which fall within the above definitions but which contain, in place of the units of the formula:

CH2=C(R)COQG(O)aSiR'd03-d/2 or of the formula:

[C112. C(R)COQC,12] blG'OSiR'd03-d 55 2 units of the formula HSiR'd03-d/2.

These organopolysiloxanes are then brought into contact with the unsaturated organic hydroxyl compounds (previously used for the preparation of the silanes of the formulae F, and F2) of the formula CH2=CRCOW0H or of the formula [CH2=C(R)COQCH2]b,G'OH, in the presence of a suitable catalyst, such 60 as a carboxylic acid salt of tin or N,N-cliethylhydroxy[amine. Hydrogen is formed according to the equation EOH + HSi ---> H2 + E0Si, the symbol E representing a radical of the general formula:

CH2=C(MCOW- or ICH2=C(R)COWHAWG' - 65 4 GB 2 101 150 A 4 and the desired linkages of the formula CH2=C(R)COQGOSi- (derived from the formula C1-12=C(R)COGG(O),,Si- in which the symbol a represents 1) and of the formula [CH,=C(R)COQCH2]b,G'OSi- are obtained.

These polymers can also be prepared starting from organopolysiloxanes which are similarto the above, 5 except that they possess units of the formula C1SiR'd03-d,2 in place of the units of the formula HSiR'd03-d/2.

In this case, HCI, and not hydrogen, is formed according to the equation EOH + C1Si ----> HCI + E0Si (IE having the above meaning), and the presence of a catalyst is no longer necessary.

They can also be prepared starting from the same type of organopolysiloxane, except that it possesses units of the formula XGSiR'd03-d/2 (X = Cl, Br) in place of the units of the formula HSiR'd03d/2 or C1SiRW3A12.

These organopolysiloxanes are then brought into contact with unsaturated organic compounds (used 10 previously for the synthesis of the silanes of the formula F,) of the formula C1-12=C(R)COW or C1-12=C(R)COQ[Vie (Me = alkali metal); an acid XH or a salt XMe is formed and the desired linkage of the formula C1- 12=C(R)COWSi-, derived from the formula C1-12=C(R)COW(O)aSi in which the symbol a represents zero, is obtained.

Concrete examples of these organopolysiloxane polymers include those of the formulae:

[CH 2= C(CH 3) CO0Cli 2 CH(C11 3)OsicH 3 ( C 6 H 5)] 2 0 [C H 2= C(CH 3) COOCH H PSi (C11 3) 201 2 si (C 6 1H 5)2 20 ((.11 C 6 11 5 si 10 Si(Cil 3)2 10 S'(CH3) Osic 6 H 5 (CH 3) 2 25 OCI GL2 NHCOCH=CH 21 5 and a copolymer consisting of: 30 5 mol % of units of the fomula CH2=C(CH3)COO(CH2)3Si(CH3)0, 3 mol % of units of the formula (CH3)3SiOO.5, 17 mol % of units of the formula (CH3)(C6H5)SiO, 45 mol % of units of the fomula CH3Si01.5 and 30 mol % of units of the formula (CH3)2SiO.

The second class of compound A includes polymers containing a certain proportion of alkoxy and/or 35 hydroxyl radicals bonded to the silicon atoms; these polymers are fairly similar to the previous polymers, but their structure is less clearly determined. They are more easily defined by the process for their preparation.

This process is characterised in that: (1) either organopolysiloxanes formed of units of the formula R'fSi044 2 in which the symbols R' and f have the same meaning as given above for the description of the units of the polymers of the first class, having a molar ratio W/Si ranging from 1.1 to 2.1 and containing from 2 to 10% of hydroxyl radicals bonded to the silicon atoms, at least 5 mol % of the radicals R' being phenyl radicals, are brought into contact with silanes chosen from formulae:

C2'C(')"Q'(0)aS'R'K"' 4a F 45 [C11 2 C (P.) COQC H j h'C'0SW C' e 3-e F4 in which the symbols R, Q, C, G', R', a and W have the same meaning as that given forthe description of the silanes of the formulae F, and F2, the symbol R- representing a methoxy or ethoxy radical and the symbol e represents zero or 1, the organopolysiloxanes and the silanes being employed in an amount sufficient to lead to a molar ratio of the hydroxyl radicals, provided by the organopolysiloxanes, to the methoxy and/or ethoxy radicals, provided by the silanes, ranging from 0.7 to 1.3, or organopolysiloxanes formed of the same 55 units of the formula WfSiO,_fi, in which the symbols R' and f have the same meaning as that given above, having the same molar ratio R'/Si 60 ranging from 1.1 to 2.1, but containing from 5 to 17% of methoxy and/or ethoxy groups, at least 5 mol % of the radicals R' being phenyl radicals, are brought into contact with unsaturated organic hydroxyl compounds, already used for the preparation of the silanes of the formulae F, and F2, of the formula CH2=C(R)COQGOH or of the formula (CH2=C(R)COQCH2)b,G'OH (the symbols R, Q, G, Tand Wthus having 65 the same meaning as that given for the description of the silanes of the formulae F, and F2), the

GB 2 101 150 A 5 organopolysiloxanes and the silanes being employed in an amount sufficient to lead to a molar ratio of the hydroxyl radicals, provided by the unsaturated organic compounds, to the methoxy and/or ethoxy radicals, provided by the organopolysiloxanes, ranging from 0.7 to 1.3, and (2) the whole is then heated in a temperature range from 15'to 170'C, in the presence of a catalyst, for a period sufficient to eliminate at most 75% of the theoretical amount of the expected alcohol (methanol and/or ethanol).

To carry out this process, the organopolysiloxanes and the silanes are mixed in proportions which make it possible to produce a molar ratio hydroxyl radicals/methoxy and/or ethoxy radicals ranging from 0.7 to 1.3, preferably from 0.75 to 1.25. A catalyst is suitably added at a rate of 0. 05 to 1 % by weight of all the reactants together. This catalyst can be, for example, an alkyl titanate or polytitanate or a carboxylic acid salt of a diorgano-tin compound. Preferably, alkyl titanates, such as isopropy], ethyl or n-butyl titanate, are used.

To facilitate the mixing of the reactants, it is possible to employ inert diluents which as halogenated or unhalogenated aliphatic, cycloaliphatic and aromatic hydrocarbons. Examples of diluents of this type include n-heptane, cyclohexane, methylcyciohexane, toluene, xylene, perch loroethylene, chlorobenzene and the various petroleum cuts.

The amount introduced is arbitrary; however, it is preferable to introduce an amount which is just sufficientto obtain the desired result, this amount frequently representing from 5 to 50% of the reactants.

The mixtures comprising the organopolysiloxanes and the silanes, the catalyst and, if appropriate, the diluents are then heated in a temperature range of 15 to 1700C, preferably at a temperature not exceeding 1150'C. During this heating, methanol or ethanol (or a mixture of the two) is eliminated at a rate of at most 75% of the expected theoretical amount, preferably of at most 70% thereof. The diluents, if present, can also 20 be eliminated by distillation or retained (partially or totally); in the latter case, they will be used subsequently to reduce the viscosity of the photopolymerisable compositions according to the invention.

By way of concrete examples, the organopolysiloxanes containing hydroxyl or alkoxy groups can be formed more especially of units chosen from amongst those of the formulae:

(C6H5)2SiO, C61-15Si01.1, C,H,(CH3)SiO, (C,H5)(CH3)2SiOO.5 (C6H5)2CH3SiOO. 5, (CH3)2SiO, (CH3)SiO,.,, 25 (CH3)(C1-12=CH)SiO (CH3)2(CH2=CH)SiOO.5, (CH3)3Si00.5.

These units, and the others covered by the formula R'fSi04412 are obviously distributed so as to give a molar ratio RVSi typically ranging from 1.1 to 2.1, preferably from 1.2 to 2; furthermore, at least 5 mol %of radicals R', preferably at least 10 mol %of these radicals, are phenyl radicals.

The organopolysiloxanes containing hydroxyl groups can be prepared in accordance with conventional methods for the hydrolysis of chlorosilanes; the latter can be brought into contact with water or mixtures of water + diluents (the diluents being miscible and/or immiscible with water). Such methods are given, in particular, in French Patent 1.581,964, U.S. Patent 3,120,500 and German Application 2,415,331.

The organopolysiloxanes containing alkoxy groups can also be prepared in accordance with conventional methods for the hydrolysis of chlorosilanes, provided, however, that methanol and/or ethanol is present in the hydrolysis medium (U.S. Patent 2,810,704).

These organopolysiloxanes can also be prepared by the hydrolysis of alkoxysilanes, chloroalkoxysilanes or mixtures of alkoxysilanes chlorosilanes. Processes of this type are given, in particular, in U.S. Patents 3,450,672,3,668,180 and 3,826,773.

When proceeding in accordance with these 2 methods of hydrolysis, the organopolysiloxanes obtained can sometimes contain a small amount, generally at most 2%, of hydroxyl radicals, apart from the methoxy 45 and ethoxy radicals. They can also be prepared by another route, namely the reaction of chlorosilanes with a mixture of methanol or ethanol and a tertiary aliphatic alcohol (French Application 2,086,349).

The silanes brought into contact with the organopolysiloxanes containing hydroxyl groups correspond to the abovementioned formulae F3 and F4. These silanes are available on the chemical products market; moreover, as they are very similar to the silanes of the formulae F, and F2, they can be prepared in accordance with the same techniques.

By way of concrete examples of these silanes, there may be mentioned those of the formulae:

CH2=C(CH3)COO-CH2CH20Si(OC2H5)3 C1-12=C(CH3)COO(CH2)3Si(OCH3)3 (CH2=CH-COOCH2)3C-CH20Si(OC2H5)3 A part of the monomeric and/or polymeric organosilicon compounds A can be replaced by liquid organic and/or organosilicon products A, also carrying groups containing aliphatic unsaturation. This fraction provides at most 75 mol % of the groups containing aliphatic unsaturation used in the compositions 60 according to the invention.

6 GB 2 101 150 A 6 These products A,, which are miscible in all proportions with the compounds A, are chosen from: the bisphenol A derivatives of the formula [CH2=C(R)COO-CH2CH20C,H4]2C(CHI)2 in which the symbol R represents a hydrogen atom or a methyl radical, and the organopolysiloxane polymers formed of 2 to 60 mol % of units of the formula CH2=CH(R1),SiO3-g,2 and 98 to 40 mol % of units of the formula (R,), Si04^g'2 in which formulae the symbol R, represents a methyl or phenyl radical, the symbol g represents zero, 1 or 2, 15 the symbol g' represents 1, 2 or 3, the molar ratio (R, + CH2=CH)/Si being generally from 1.4 to 2.3, and at least 5 mol % of radicals R, are phenyl radicals.

The bisphenol A derivatives include the compounds of the formulae:

H C(CII)CoO-Cl! C11,0-C I-,, c (cil [C 2 3 2 b 12 3 20 [C H 2= CII-COO-CH 2 CIL)0C 6 H j 2C(C9 2 which have viscosities of, say, 2,000 mPa.s at 2WC.

The org a nopolysi I oxane polymers A, are formed of units chosen more especially from those of the 25 formulae:

CH,SiO,, (CHI)2SiO, (CH3)3SiOl.1, CH2=CHSiO,, CH,=CH(CH,)SiO, CH2=CH(CH32SiOl.1, CH2=CH'kCH3)C6H5SiOO 5, (C6H5)SiOl.5, (C6H5)2SiO, C6115(CHASiO, C61-15(CHA2Si00.5, (C,H5)2CH3SiOl.5. 30 These units are desirably distributed so as to satisfy the abovementioned requirements, in particularthat: 30 the molar ratio (R, + C1-12=CH)/Si ranges from 1.4 to 2.3, preferably from 1.5 to 2.2, and at least 5 mol %, preferably 10 mol % of the radicals R, are phenyl radicals. The bisphenol A derivatives are available on the chemical products market; the same applies to the organosilicon products A,. Moreover, the latter can easily be prepared by hydrolysis techniques already described. One of these techniques consists, for example, in:

hydrolysing chlorosilanes chosen from those leading to the units illustrated above, and treating the hydrolysates under the action of heat, in the presence of a catalyst permitting the rearrangement of the siloxane linkages and the condensation of the radicals Si-OH (French Patent 1,568,812).

The organohydrogenopolysiloxane B carries at least one hydrogen atom and at least one phenyl radical, 40 bonded to all its silicon atoms, the other radicals being methyl radicals. This polymer can have any degree of polymerisation and can be in the form of an oil, a gum or a resin. Preferably, however, the organohydrogenopolysiloxane B is an oil having a viscosity of at most 100, 000 mPa.s at 25'C, which is formed of a succession of units chosen from those of the formulae:

SiO,, HSiO,, CH,(HOO, CH,SiO,.,, (CH,),SiO, (CH,),HSiO,.,, (CH,)3SiOO.5, C,H,SiOl.,, CM(CH,)SiO, (C6H5)2SiO, C61-15(CHA2SiOTI, C6H,(H)SiO, (C6H5)2CH3SiOl.1, and distributed so as to lead to the following molar ratios: C6H5Si ranging from 0.2 to 1.5, preferably 0.3 to 1.4 CH3.1Si ranging from 0.4 to 2, preferably 0.5 to 1.9 H, Si ranging from 0.1 to 1, preferably 0.2 to 0.9 (C6HF, + CH3 + H);Si... ranging from 1.6 to 3, preferably 1.7 to 2.8.

This polymer can be prepared simply by the co-hydrolysis of suitable mixtures of chlorosilanes, the said chlorosilanes obviously having a structure which is directly related to that of the units set out above.

Moreover, in order to assist the condensation of the SiOH groups present in the reaction medium, the 55 co-hydrolysates are preferably heated with a catalyst (e.g. sulphuric acid or clay activated by an acid), which not only favours the condensation of the SiOH groups, but also causes a rearrangement of the siloxane linkages (French Patent 2,280,956).

The components A and B are employed in amounts sufficient to lead to a molar ratio of the Sil-1 groups, provided by the organohydrogenopolysiloxane B, to the groups containing aliphatic unsaturation of the 60 formula C1-12=CH(R)COQ-, provided by the compound A, ranging from 0.5 to 7, preferably from 0.6 to 5. As already indicated, at most 75 mol %, preferably at most 70 mol %, of the above groups containing aliphatic unsaturation can be replaced by other groups containing aliphatic unsaturation, provided by the compounds A,.

The photoinitiator or photosensitiser C is used in an amount of 0.1 to 10 parts, pereferably of 0.5 to 8 parts, 65 7 GB 2 101 150 A 7 per 100 parts of the components A and B together. It is chosen, for example, from amongst derivatives of benzoin, of xanthone and of thioxanthone.

Concrete examples of such photosensitisers include:

alkyl ethers of benzoin, or mixtures thereof, in which the alkyl radical contains from 1 to 6 carbon atoms, 5 and more especially the n-propyl, isopropyl, n-butyl and isobutyl ethers, 3-chloroxanthone and 3methoxyxanthone, and 2-chlorothioxanthone.

Othertypes of photosensitisers can also be employed, such as aromatic ketone derivatives, for example acetophenone, benzophenone and 4,4'-bis(dimethylamino)-benzophenone. However, the latter compounds sometimes give less good results than the previous compounds, or they should be used in conjunction with 10 a co-initiator (for example triethylamine or triethyl phosphite).

An organic diluent D, which is inert towards the components A, B and C, can be employed at a rate of at most 150 parts, preferably at most 140 parts, per 100 parts of the compounds A and B together. This diluent is used in order to facilitate the mixing of the constituents A, B and C and also to reduce the viscosity of the organopolysiloxane composition so that it does not exceed 10,000 mPa.s at 25'C, preferably 9,000 mPa.s at 15 2WC. Its use is not necessary if the constituents A and B are oily products of fairly low viscosity, for example of less than 500 m Pa.s at 25'C.

It can be a conventional diluent, such as those already mentioned for the preparation of the organopolysiloxanes containing a certain proportion of alkyl and/or hydroxyl radicals. Thus, these diluents can be halogenated or unhalogenated aliphatic, cycloaliphatic or aromatic hydrocarbons, amongst which 20 there may be mentioned, by way of illustration, n-heptane, cyclohexane, methylcyclohexane, toluene, xylene, perch 1 o roethyl ene, chlorobenzene and the various petroleum cuts.

The photopolymerisable compositions according to the invention are prepared by intimately mixing the components A, B and C and, if appropriate, D and A,. The various constituents need not be introduced in strict order; however, it is preferable first to mix the constituent A (and the optional constituent A,) and the 25 constituent B, to stir the mixture until a homogeneous liquid is obtained, and then to add the photosensitiser.

The diluent D, if it is employed, can be added during the mixing of A and B, or alternatively it can be introduced in the form of the solvent in a solution of the compound A and/or the compound B. The photopolymerisable compositions thus obtained can be applied (to all kinds of substrate) in accordance with common techniques, for example by dipping, with a brush, with a coating knife, with a spray gun or by centrifugation. They form (after evaporation of the diluent D, if present) homogeneous coatings having a thickness of, say, a few microns up to 200 microns.

These coatings can be hardened by exposure to ultraviolet radiation produced by xenon lamps or mercury arc lamps, the emission spectrum of which generally ranges from 250 to about 450 nm; the exposure time isvariable; it can be a few seconds or can be as much as, say, one hundred seconds. The coatings have:

good mechanical properties, in particular a high impact strength, a high stamping resistance, and a high toughness and flexibility, a good solvent resistance, a good resistance to cold, good electrical properties, in particular a high dielectric strength value, a low thermoplasticity and excellent adhesion to the materials which they cover.

They can cover, and thus protect, materials of any nature, for example:

metals based on iron, steel, aluminium, copper, brass, bronze, lead, titanium, vanadium, cadmium and silicon, organic polymers consisting of polyolefines, polyamides, polyurethanes, polyethers, polycarbonates, polyepoxides, polyesters, phenol/formaldehyde resins and melamine/formaldehyde resins, organic and synthetic rubbers consisting of butadiene/styrene, isobutylene/isoprene, acrylonitrilel butadiene and silicone, the different varieties of paper and cardboard, fabrics based on synthetic or natural fibres, glass fibres and asbestos fibres, mineral substances based on silica and silicates.

They can be used in numerous fields of application and more especially in electronics for the protection of printed circuits, integrated circuits and also various wiring arrangements. Apart from the remarkable 55 properties referred to above, the value of these coatings lies in their easy preparation, which does not require high temperatures.

The Examples which follow further illustrate this invention.

8 GB 2 101 150 A 8 Example 1

The following are introduced into a reactor equipped with a stirrer:

g of a methylphenyihydrogenopolysiloxane polymer P, which consists of units C6H5Si01.5, (C6H5)2SiO, (CH3)3SiOO.5 and CHAH)SiO distributed so as to lead to molar ratios CH3/Si, CE;H5/Si and H/Si respectively having the values 0.75, 0.7 and 0.45, which has a viscosity of 4,000 mPa. s at 25'C and which has about 11.3% 5 of Sil-1 groups, and 16.5 g of the silane of the formula [CH2=C(CH3)COOCH2CH2012Si(C,H1)2.

The 20 g of polymer P, contain 0.078 mol of SM groups and the 16.5 g of the silane contain 0.074 mol of vinyl groups; the ratio Sil-l/Si-vinyl is of the order of 1.04. (The radicals C1-12=C(C1-13)- are considered as vinyl groups).

The 2 products are stirred until a homogeneous solution is obtained, and 1.5 g of a photoinitiator T1, consisting of the isopropyl ether of benzoin, are introduced into the reactor. The whole is stirred for 2 hours. 15 The composition obtained, which has a viscosity of 2,200 mPa.s at 25'C, is coated onto one of the 2 faces of degreased aluminium plates. The coating thus deposited has a thickness of 100 microns. It is hardened by exposure to ultraviolet radiation for 90 seconds. This radiation is emitted by a mercury vapour lamp having a power of 5,000 W and equipped with an elliptical reflector. The frontal zone of the lamp is located at a distance of 5.6 cm from the coated face of the aluminium plates. This lamp emits mainly in the near ultraviolet with a maximum at 36 nm.

The hardened coating has the following characteristics:

no thermoplasticity up to 140'C; the test relating to the determination of the thermoplasticity consists in keeping 2 aluminium plates, arranged with the coated faces against one another, between 2 heating platens, for 10 seconds, under a pressure of 5.105 Pa, and in noting the value of the temperature above which the 25 plates can no longer be separated from one another; no modification at -60'C; the test relating to the determination of the modifications of the physical characteristics at low temperatures consists in placing the coated aluminium plates in a cold box, which is regulated so as to provide temperature plateaus, lasting 24 hours, every time the temperature falls by 10 degrees. The appearance of the coatings, that is to say whether or not cracking has taken place, is noted at 30 each plateau; no solubility in trichloroethylene or in the trichlorotrifluoroethane of theformula CC12FWIF2; thetest relating to the determination of the solubility consists in immersing the coated aluminium plates in the solvent for 4 hours, at ambient temperature. After drying in air, the appearance of the coatings is noted: no modifications, embrittled zones, appearance of blisters, complete dissolution; and a dielectric strength of 100 W;mm; to measure this strength, electrodes of diameter 6.35 mm, a voltage increase of 500 volts/second and an alternating current of 500 Hz are used.

Example 2

The following are introduced into a reactor equipped with a stirrer:

g of the methyl phenyl hydrogenopolysiloxane polymer P, used in Example 1, 4.56 g of the silane of the formula [CH2=C(CH3)COOCH2CH2012Si(C6H5)2 and 4.44 g of the unsaturated compound of the formula [CH2=C(CH3)COOCH2CH20C6H4]2C(CH3)2.

The 20 g of polymer P, contain 0.078 mol of Sil-1 groups, the 4.56 g of the silane contain 0.0206 mol of vinyl groups and the 4.44 g of the unsaturated compound contain 0.0196 mol of vinyl groups: the molar ratio 45 Sil-l/Si-vinyl is of the order of 1.9.

The 3 products are stirred until a homogeneous product is obtained, and 1. 16 g of the photoinitiator T1 used in Example 1 are added. The whole is stirred for 1 hour 30 minutes.

The composition obtained, which has a viscosity of 3,100 mPa.s at 25'C, is applied, by dipping, to the surface of printed circuits with 2 branches, each circuit being located on one face of a plate consisting of a 50 glass.epoxy resin laminate. The coating thus formed, which has a thickness of about 30 microns, is hardened by photocross-linking under the conditions given in Example 1 for exposure to ultraviolet radiation.

The insulation resistance of each printed circuit is measured under a voltage of 500 V, after exposure of each plate to the atmosphere (the temperature is 20'C and the relative humidity is 50%). It reaches 800 x 1010 ohm.cm and remains virtually at this value, irrespective of the number of days of exposure to these 55 temperature and humidity conditions.

The insulation resistance is then measured under the same voltage, but after exposure of each plate to a temperature of 45'C and a relative humidity of 95%. It reaches 580 x 1010 ohm.cm after 10 days of exposure and 25 x 1010 ohm.cm after 56 days of exposure. These values are high, even though the environmental conditions are severe; they show the good insulating character and the good adhesion of the coating to the 60 printed circuits.

Example 3

The following are introduced into a reactor equipped with a stirrer:

20 9 of the methyl phenyl hydrogenopolysiloxa ne polymer P, used in Example 1, 9 GB 2 101 150 A 9 12.45 9 of the silane of the formula [CH2=C(CH3)COOCH2CH2012Si(C6H5)2 and 7.6 9 of the methyl phenylvi nyl po lysil oxane polymer which consists of units (CH3)SiOl.5, (CH3)2SiO, C1-13(CH =CH)SiO and (C61-15)2SiO distributed so as to lead to molar ratios CH3/Si, (C6H5/Si and vinyl/Si respectively having the values 0.8, 0.75 and 0.3, which has a viscosity of 3,500 mPa.s at 2WC and which has 5 about 6% of vinyl groups.

The 20 g of polymer P, contain 0.078 mol of SiH groups, the 12.45 g of the silane contain 0.056 mol of vinyl groups and the 7.6 g of the methyl phenylvi nyl polysiloxane polymer contain 0.016 mol of vinyl groups: the molar ratio SH/Si-vinyl is of the order of 1.1.

The 3 products are stirred until a homogeneous liquid is obtained, and 1. 6 g of the photoinitiator used in Example 1 are added. The whole is stirred for 2 hours.

The composition obtained, which has a viscosity of 2,600 mPa.s at 2WC, is applied, by centrifugation, to one of the faces of degreased aluminium plates; the coating thus formed, which has a thickness of 100 microns, is hardened by photocrosslinking under the conditions given in Example 1 for exposure to ultraviolet radiation.

This coating possesses the properties of the coating described in Example 1: no thermoplasticity up to 15 140'C, no change in the physical characteristics at -60'C, no solubility in trichloroethylene or in the trichlorotrifluoroethylene of the formula CC12MCIF2, and a dielectric strength of 100 kV/mm.

The composition is also applied by spraying, not to aluminium plates but to one of the faces of silica plates. The coating formed, which has a thickness of 25 microns, is hardened by photocrosslinking under the conditions given in Example 1 for exposure to ultraviolet radiation.

A very good adhesion (rating 5) of the coating is found. This adhesion is measured in accordance with a grid test which satisfies French Standard Specification 03,038. This test is as follows: a grid is formed on the coating by means of a scratching comb with teeth spaced 1 mm apart, the incisions being made as far as the substrate. An adhesive tape is then applied to the small 1 MM2 squares thus formed; the tape is then removed and the condition of the coating is examined. This condition is assessed according to a rating from 25 1 to 5:

Rating 5: no zone of coating has been detached Rating 4: small zones of the coating which represent about 5% of the total surface area have been detached Rating 3: zones of the coating which represent about 15% of the total surface area have been detached 30 Rating 2: wide zones of the coating which represent about 35% of the total surface have been detached Rating 1: very large zones of the coating which represent about 65% of the total surface area have been detached.

Furthermore, the adhesion remains good after exposure of the coating to 32 accelerated ageing cycles on a Weatherometer.

Example 4 The following are introduced into a reactor equipped with a stirrer: 20 9 of the methyl phenyl hyd rogenopolysi loxa ne polymer P, used in Example 1, and 40 23.2 g of the trisiloxane of the formula [CH2=C(CH3)COOCH2CH2OSI(CH3)202Si(C6H5)2. The 20 g of polymer P, contain 0.078 mol of SiH groups and the 23.2 g of the trisiloxane contain 0.08 mol of vinyl groups: the molar ratio SM/Si-vinyl is of the order of 1. The 2 products are stirred until a homogeneous liquid is obtained, and 1. 7 g of the photoinitiator T1 used in Example 1 are added. The whole is stirred for 1 hour 45 minutes. 45 The composition obtained, which had a viscosity of 1,900 mPa.s at 2WC, is coated onto one of the faces of 45 degreased steel plates. The coating thus formed has a thickness of 15 microns; it is hardened by exposure to ultraviolet radiation under the exposure conditions given in Example 1, except that the exposure time is 60 seconds instead of 90 seconds. A very good adhesion of the coating to the steel plates is found (rating 5). This adhesion is measured in 50 accordance with the grid test described in Example 3. A very good impact strength of the coating is also found (rating 5). This strength is measured in accordance with a test which is derived from French Standard Specification 30,039. This test is as follows: the coating is subjected to the impact of a 1 kg steel weight, the impact being caused by the guided vertical failing of this weight from a height of 50 cm. An adhesive tape is applied to the impact zone. After removal of the tape, the condition of the coating is examined and assessed 55 using the rating for the grid test, described in Example 3.

Example 5 (e) The following are introduced into a reactor equipped with a stirrer, a thermometer sleeve and a swan-neck surmounted by an analyser:

70 g of a solid methyl phenyl polysi loxane polymer which consists of units C61-15Si01.5, (CH3)2SiO and 60 CH3SiOl.,5 distributed so as to lead to molar ratios C6H5/Si and CH3/Si each having the value 0.625, which has a melting point of 8M and which contains about 5% of OH groups, 19 g of the silane of the formula CH2=C(CH3)COO(CH2)3)Si(OCH3)3, g of toluene and 0.18 9 of tetraisopropyl titanate.

GB 2 101 150 A The 70 g of the methyl phenyl polysiloxa ne polymer contain 0.206 mol of OH groups and the 19 g of the silane contain 0.228 mol of methoxy groups: the molar ratio OH/OCH3 is of the order of 0.9.

The contents of the reactor are heated progressively from 2WC to 1WC in a period of 50 minutes; during this heating, volatile products are eliminated, in particular 4.7 g of methanol; this amount represents 71% of 5 the expected theoretical amount of 6.59 g.

The homogeneous condensate obtained has a viscosity of 1,000 mPa.s at 25'C; it contains about 25% of toluene and 0.07 mol of vinyl groups per 100 g.

(2e) The following are introduced into a reactor equipped with a stirrer:

g of the methyl phenyl hydrogenopolysiloxane polymer P, used in Example 1, and 55 g of the above condensate.

The 20 9 of polymer P, contain 0.078 mol of SH groups and the 55 g of the condensate contain 0.038 mol of vinyl groups: the molar ratio SM/Si-vinyl is of the order of 2.

The 2 products are stirred until a homogeneous liquid containing 18.1% of toluene is obtained, and 2.47g of the photoinitiator T1 used in Example 1 are added. The whole is stirred for 2 hours.

The composition obtained, which has a viscosity of 1,800 mPa.s at 25'C, is coated onto one of the faces of 15 degreased aluminium plates. The deposited layer is dried by passing the plates under a ventilated hood. A coating having a thickness of 75 microns remains and this is hardened by photocrosslinking under the conditions given in Example 1 for exposure to ultraviolet radiation; however, the exposure time is only 12 seconds.

The coating on the plates is subjected to the following tests: adhesion in the arid test.....................

. RATING 3 (this test is the one described in Example 3) impact strength RATING 5 (this impact strength test is the one described in Example 4) stamping resistance (Erichsen test) RATING 3 The stamping resistance is measured in accordance with a test which is derived from French Standard Specification 30,019.

This test is as follows: the coating is marked out into 1 MM2 squares with the aid of the scratching comb used to carry out the grid test, the incisions being made as far as the substrate. The coating marked out in this way is subjected to a progressive stamping of 5 mm. An adhesive tape is applied to the stamping zone; 30 after removal of the tape, the condition of the coating is examined and assessed according to the rating for the grid test, described in Example 3.

By way of comparison, a similar coating having a thickness of 75 microns is produced, but starting from a composition containing only the condensate; thus, this composition is obtained by mixing 75 g of the condensate with 2.47 g of the photoinitiator T1.

This new coating is subjected to the above tests; the ratings are as follows adhesion in the grid test: 1 impact strength: 1 stamping resistance (Erichsen test):...................................... .................................................................. 1 The absence of the methyl phenyl hydrogenopolysiloxane polymer P, in the composition does not 40 therefore make it possible to produce a coating having good properties.

Example 6

The following are introduced into a reactor equipped with a stirrer:

20 9 of the methyl phenyl hydrogenopolysiloxane polymer P, used in Example 1, and 22 9 of the condensate prepared in Example 5 under (e).

The 20 g of polymer P, contain 0.078 mol of SH groups and the 22 g of the condensate contain 0.0154 mol of vinyl groups: the molar ratio SiH/Sivinyl is of the order of 5.

The 2 products are stirred until a homogeneous liquid is obtained, and 1. 38 g of the photoinitiatorT, are added. The whole is stirred for 1 hour 30 minutes.

The composition obtained, which has a viscosity of 2,400 mPa.s at 25oC, is coated onto one of the 2 faces of degreased aluminium plates and the deposited layer is then dried. The coating formed, which has a thickness of 75 microns, is hardened under the conditions given in Example 1 for exposure to ultraviolet radiation, but the exposure time is only 12 seconds. This coating is subjected to the same tests as those used in Example 5. The ratings are as follows: adhesion in the grid test:...... ........................ impact strength:................................. ...................................................... stamping resistance (Erichsen test):............................................... .....

Example 7 (f) The following are introduced into a reactor equipped with a stirrer, a thermometer sleeve and a swan-neck surmounted in an analyser:

g of hydroxyethyl acrylate of the formula CH2=CH-COO-CH2CH20H, 471 g of a methyl phenyl polysi 1 oxa ne polymer P2 which consists of units C6H5Si01.5, (C6H5)2SiO and 65 11 GB 2 101 150 A 11 (CH3)2SiO distributed so as to lead to molar ratios C61-15/Si and CH3/Si respectively having the values 0.9 and 0.7, which has a viscosity of 125 mPa.s at 25'C and which contains about 12.6% of methoxy groups, and 1.34 9 of isopropyl titanate.

The 200 g of hydroxyethyl acrylate contain 1.72 mols of OH groups and the 471 g of polymer P2 contain 5 1.91 mols of OCH3 groups: the molar ratio OH/OCH3 is of the order of 0.9.

The contents of the reactor are heated progressively from 200C to 1250C in a period of 55 minutes. During this heating, 8.1 g of methanol are eliminated. This amount represents 14.7% of the expected theoretical amount of methanol of 55.04 g.

The homogeneous condensate obtained has a viscosity of 80 mPa.s at 250C; it contains about 0.259 mol of vinyl groups per 100 g.

(2f) The following are introduced into a reactor equipped with a stirrer:

g of the methyl phenyl hydrogenopolysiloxane polymer P, used in Example 1, and 29.7 g of the above condensate.

The 20 g of polymer P, contain 0.078 mol of SiH groups and the 29.7 g of the condensate contain 0.077 mol of vinyl groups: the molar ratio SM/Si-vinyl is of the order of 1.

The 2 products are stirred until a homogeneous liquid is obtained, and 1. 98 g of the photoinitiatorT, used in Example 1 are added. The whole is stirred for 1 hour.

The composition obtained, which has a viscosity of 1,600 mPa.s at 250C, is coated onto one of the 2 faces of aluminium plates degreased beforehand. The deposited coating, which has a thickness of 20 microns, is hardened by photocrosslinking under the conditions given in Example 1 for exposure to ultraviolet radiation, 20 except that the exposure time is only 30 seconds.

This coating is subjected to the same tests as those used in Example 5. The ratings are as follows:

adhesion in the grid test:................................................ .......................................................................... 5 stamping resistance (Erichsen test) Example 8

The following are introduced into a reactor equipped with a stirrer:

20 g of the methyl phenyl hydrogenopolysi loxa ne polymer P, used in Example 1, 7.30 g of the condensate prepared in Example 7 under (f), and 7.30 9 of the unsaturated compound of the formula[CH2=C(CH3)COOCH2CH20C6H4]2C(CH3)2.

The 20 g of polymer P, contain 0.078 mol of SM groups, the 7.30 g of the condensate contain 0.019 mol of vinyl groups and the 7.30 g of the unsaturated compound contain 0.032 mol of vinyl groups: the molar ratio SiH/Si-vinyl is of the order of 1.5.

The 3 products are stirred until a homogeneous liquid is obtained, and 1. 38 g of the photoinitiator T1 used in Example 1 are added. The whole is stirred for 1 hour.

The composition obtained, which has a viscosity of 2,700 mPa.s at 25'C, is coated onto one of the 2 faces of aluminium plates degreased beforehand. The coating thus formed, which has a thickness of 20 microns, is hardened by photocrosslinking under the conditions given in Example 1 for exposure to ultraviolet radiation. 40 This coating is subjected to the same tests as those used in Example 5. The ratings are as follows:

adhesion in the grid test: 5 stamping resistance (Erichsen test) 5 By way of comparison, a similar coating having a thickness of 20 microns is produced, but starting from a composition not containing polymer P, (the 20 g of this polymer are replaced by 10 g of the condensate and g of the unsaturated compound). This new coating is subjected to the above tests. The ratings are as follows:

adhesion in the grid test:

impact strength...............

stamping resistance (Erichsen test) Example 9

The following are introduced into a reactor equipped with a stirrer:

g of the methyl phenyl hydrogenopolysiloxa ne polymer P, used in Example 1, 5.5 g of the condensate prepared in Example 7 under (f), and 5.5 g of the unsaturated compound of the formula [CH2=C(CH3)COOCH2CH20C6H4]C(CH3)2.

The 20 g of polymer P, contain 0.078 mol of SiH groups, the 5.5 g of the condensate contain 0.014 mol of 60 vinyl groups and the 5.5 g of the unsaturated compound contain 0.024 mol of vinyl groups: the molar ratio SiH/Si-vinyl is of the order of 2.

The 3 products are stirred until a homogeneous liquid is obtained, and 1. 24 g of the photoinitiator T1 used in Example 1 are added. The whole is stirred for 1 hour.

The composition obtained, which has a viscosity of 3,000 mPa.s at 2WC, is coated onto one of the 2 faces of65 12 GB 2 101 150 A aluminium plates degreased beforehand. The coating formed, which has a thickness of 40 microns, is hardened under the conditions given in Example 1 for exposure to ultraviolet radiation. This coating is subjected to the same tests as those described in Example 5. The ratings for the 3 tests are 5.

Example 10 (g) The following are introduced into a reactor equipped with a stirrer, a thermometer sleeve and a swan-neck surmounted by an analyser:

g of propylene glycol acrylate of the formula CH2=CH-COOCH2CHOH-CH3, 75.5 g of the methyl phenylpolysiloxane polymer P2 used in Example 7, and 0.23 g of tetraisopropyl titanate.

The 40 g of propylene glycol acrylate contain 0.3 mol of hydroxyl groups and the 75.5 g of polymer P2 contain 0.29 mol of methoxy groups: the molar ratio OH/OCH3 is of the order of 1.

The contents of the reactor are heated progressively from 2WC to 16WC in a period of 1 hour. During this heating, 5.2 9 of methanol are eliminated, which represents 54% of the theoretical amount of methanol of 9.6 g. The homogeneous condensate thus formed has a viscosity of 520 mPa. s at 2WC; it contains about 15 0.278 mol of vinyl groups per 100 g. (2g) The following are introduced into a reactor equipped with a stirrer: 20 9 of the methyl phenyl hyd rogenopolysil oxa ne polymer P, used in Example 1, and 27 9 of the above condensate. 20 The 20 9 of polymer P, contain 0.078 mol of SiH groups and the 27 g of the condensate contain 0.075 mol 20 of vinyl groups: the molar ratio SiH/Si-vinyl is of the order of 1. This mixture is stirred until a homogeneous liquid is obtained, and 1.88 9 of the photoinitiatorT, used in Example 1 are then added; the whole is stirred for 1 hour. The composition obtained, which has a viscosity of 2,000 mPa.s at 2WC, is sprayed onto one of the 2 faces of degreased aluminium plates. The deposited coating, which has a thickness of 36 microns, is hardened by photocrossi inking under the conditions given in Example 1 for exposure to ultraviolet radiation, except that the exposure time is only 60 seconds. This coating is subjected to the same tests as those described in Example 5. The ratings are as follows:

12 adhesion in the grid test: 5 impact strength: 5 30 stamping resistance (Erichsen test):...................................... .................................................................. 5 Example 11 (h) The following are introduced into a reactor equipped with a stirrer, a thermometer sleeve and a swan-neck surmounted by an analyser:

37.5 g of pentaerythritol triacrylate of the formula (CH2=CH-COOCH2)3CCH20H, 31.20 g of the methyl phenylpolysiloxane polymer P2 used in Example 7, g of toluene and 0.14 g of tetraisopropyl titanate.

The 37.5 g of pentaerythritol triacrylate contain 0.126 mol of hydroxyl groups and the 31.20 9 of polymer P2 40 contain 0.127 mol of methoxy groups: the molar ratio 0H/OCH3 is of the order of 1.

The contents of the reactor are heated progressively from 2WC to 12WC in a period of 1 hour 10 minutes.

During this heating, volatile compounds are eliminated, in particular 0.5 g of methanol, which represents 12.4% of the expected theoretical amount of methanol of 4.03 g. The condensate obtained has a viscosity of 200 mPa.s at 25'C; it contains about 0.513 mol of vinyl groups per 100 g.

(2h) The following are introduced into a reactor equipped with a stirrer:

g of the methyl phenyl hyd rogenopolysi loxa ne polymer P, used in Example 1, and 14 g of the above condensate.

The 20 g of polymer P, contain 0.078 mol of SiH groups and the 14 g of the condensate contain 0.077 mol of vinyl groups: the molar ratio Sil-l/Si-vinyl is of the order of 1.

The mixture is stirred until a homogeneous liquid is obtained, and 1.32 g of the photoinitiator T1 used in Example 1 are then added. The whole is stirred for 1 hour30 minutes.

The composition obtained, which has a viscosity of 2,200 mPa.s at 25'C, is applied, by centrifugation, to one of the 2 faces of degreased aluminium plates. After drying in air, the deposited coating has a thickness of 50 microns. It is hardened by photocrosslinking under the conditions given in Example 1 for exposure to 55 ultraviolet radiation; however, the exposure time is only 40 seconds.

adhesion in the impact strength stamping resistance (Erichsen test) GB 2 101 150 A 13 Byway of comparison, a similar coating having a thickness of 50 microns, hardened underthe same conditions, is produced, but starting from a composition containing only the condensate (this composition is obtained by mixing 34 g of t he condensate with 1.32 g of the photoinitiator T1). This new coating is subjected to the above tests; the ratings are as follows:

adhesion in the grid test........................

stamping resistance (Erichsen test) ................... 1 5 Example 12 (i) The following are introduced into a reactor equipped with a stirrer, a thermometer sleeve and a 10 swan-neck surmounted by an analyser:

g of the amide of the formula CH2=CH-CONI-I-CH201-1, having a melting point of 75'C, 22.2 g of the methylphenylpolysiioxane polymer P2 used in Example 7 (however, it contains 13.8% of methoxy groups instead of 12.6%), 20 9 of dimethylformamide and 0.06 9 of isopropyl titanate.

The 10 g of amide contain 0.099 mol of hydroxyl groups and the 22.2 g of polymer P2 contain 0.099 mol of methoxy groups: the molar ratio OH/OCH3 is of the order of 1.

The contents of the reactor are heated gradually from 200C to 1380C in a period of 1 hour. During this heating, 0.32 g of methanol is eliminated, that is to say 10% of the expected theoretical amount of methanol. 20 The dimethylformamide is removed from the condensate by heating under reduced pressure at a temperature not exceeding WC. The condensate is a solid product having a softening point of 7WC and containing 0.309 mol of vinyl groups per 100 g.

(2i) The following are introduced into a reactor equipped with a stirrer:

20 9 of the methylphenylhydrogenopolysiloxane polymer P, used in Example 1, and 22.4 g of the above condensate.

The 20 g of polymer P, contain 0.078 mol of SiH groups and the 22.4 g of the condensate contain 0.069 mol of vinyl groups: the molar ratio SM/S1vinyl is of the order of 1.

This mixture is stirred until a homogeneous liquid is obtained, and 1.77 9 of the photoinitiatorT, described in Example 1 are then added. The whole is stirred for 1 hour.

The composition obtained, which has a viscosity of 5,000 mPa.s at 25'C, is applied, by dipping, to the surface of degreased aluminium plates. The deposited coating has a thickness of 60 microns. It is hardened on one face of the plates by photocrosslinking under the conditions given in Example 1 for exposure to ultraviolet radiation, except that the exposure time is 30 seconds. The hardened coating is subjected to the same testsas those used in Example 5. The ratings are as follows:

adhesionin the grid test.................................................. ..........................................................................

stamping resistance (Erichsen test)

Claims

CLAIMS 1. A photopolymerisable liquid organopolysiloxane composition having a viscosity from 100 mPa.s at 25'C to 10,000 mPa.s at 25'C, which is in the form of a mixture of: A - at least one monomeric or polymeric organosilicon compound carrying, bonded to its silicon atom or atoms:

1) at least one organic radical containing an unsaturated group of the formula C1-12=C(R)COQ-, in which the symbol R represents a hydrogen atom or a methyl radical and the symbol Q represents 0 or NH, and 2) at least one phenyl radical, the other organic radicals being methyl, ethyl, propy], 3,3,3-trifluoropropyl or vinyl radicals, alkoxy radicals having from 1 to 5 carbon atoms, or P- methoxyethoxy or hydroxyl radicals, 50 B at least one organohydrogenopolysiloxane carrying, bonded to its silicon atoms, at least one hydrogen atom and at least one phenyl radical, the other radicals being methyl radicals, the components A and B being employed in amounts so as to give a molar ratio of the groups SiH, provided by the organohydrogenopolysiloxane B, to the groups CH2=CRCOQ-, provided by the compound A, from 0.5A to 7: 1, C - a photosensitiser which is a derivative of benzoin, xanthone or thioxanthone, in an amountfrom 0.1 to 55 10 parts per 100 parts of components A and B together, and, optionally, D - an organic diluent which is inert towards components A, B and C, in an amount up to 150 parts per 100 parts of components A and B together.

2. A composition according to claim 1, in which compound A is a silane of the general formula:

5 [CH 2=C(R)COQG(O) alb SiR' C W' 4-b-c [CH 2=C(R)COQCH 21b, G'OSiR' c Rn 3-c 14 GB 2 101 150 A 14 in which: the symbols R and Q are as defined in claim 1, the symbol G represents a linear or branched alkylene radical having from 1 to 5 carbon atoms, the symbol G' represents a trivalent ortetravalent, linear or branched aliphatic radical having from 1 to 5 carbon atoms, the symbol R' represents a methyl, ethyl, propy], phenyl, vinyl or 3,3,3-trifluoropropyl radical, the symbol W' represents an alkoxy radical having from 1 to 5 carbon atoms or a P-methoxyethoxy radical. the symbol a represents zero or 1, the symbol b represents 1, 2 5 or 3 when a = 1, and only 1 when a = zero, the symbol c represents 1, 2 or 3, the symbol W represents 2 or 3, and at least one radical R' represents a phenyl radical.

3. A composition according to claim 1, in which compound A is a linear or branched organopolysiloxane polymer which is either liquid and has a viscosity of at most 30,000 mPa. s at 25T, or solid and has a melting point below 120T, the polymer being either one which contains substantially no alkoxy and/or hydroxyl radicals bonded to the silicon atoms, or one which contains these radicals.

4. A composition according to claim 3 in which the organopolysiloxane polymer consists of:

1 to 100 mol % of units of the formula:

o r and/or CH 2=C(R)COQG(O) a SiR' d 0 3 -d 2 [CH 2=C(R)COQC11 21b GlOSiR' d 0 3-d 2 in which the symbols R, Q, R', G, G', a and W are as defined in claim 2 and the symbol cl represents 1 or 2, and 99 to 0 mole % of units of the formula:

WISiOIA12 in which the symbol R' is as defined in claim 2, the symbol f represents 1, 2 or 3, the molar ratio (R' + Z)Si being from 1.4 to 3, the symbol Z representing a radical of the general formula:

CH2=C(R)COQG(O-)a (CH2=C(R)COQCH2)b,G'O-, such that at least 5 mol % of radicals R' are phenyl radicals.

5. A composition according to claim 3 in which the organopolysiloxane is one prepared by:

1) contacting an organopolysiloxane formed of units of the formula:

WfSiOl-f 2 in which the symbols R' and fare as defined in claim 4, having a molar ratio W/Si from 1.1A to 2.1A and containing from 2 to 10% of hydroxyl radicals bonded to the silicon atoms, at least 5 mol %of the radicals R' being phenyl radicals, with a silane of the formula:

CH 2C(R)COQG(O) a SiR' e R 4-e or [CII 2=C(R)COQC11 21bl G'OSiR' e R 3-e 50 in which the symbols R, G, G, G', R', a and W are as defined in claim 2, the symbol R... represents a methoxy or ethoxy radical and the symbol e represents zero or 1, the organopolysiloxanes and the silanes being in amounts such as to provide a molar ratio of the hydroxyl radicals, provided by the organopolysiloxanes, to 55 the methoxy and/or ethoxy radicals, provided by the silanes, from 0.7A to 1.3A and 2) heating the whole in a temperature range from 15'to 170T, in the presence of a catalyst, for a period sufficient to eliminate at most 75% of the theoretical amount of the expected alcohol (methanol and/or ethanol).

6. A composition according to claim 3 in which the organopolysiloxane is one prepared by: 60 1) contacting an organopolysiloxane formed of units of the formula WfSi01412 in which the symbols R' and fare as defined in claim 4, the said molar ratio W/Si being from M:1 to 2.1A and containing from 5to 17% of methoxy and/or ethoxy groups, at least 5 mol %of the radicals R' being 65 GB 2 101 150 A 15 phenyl radicals, with an unsaturated organic hydroxyl compound of the formula:

CH2=C(R)COQGOH or [CH2=C(R)COQCH2]b,G'OH in which the symbols R, Q, G, Tand Ware as defined in claim 2,the organopolysiloxanes and the silanes being employed in an amount such as to provide a molar ratio of the hydroxyl radicals, provided by the unsaturated organic compounds, to the methoxy and/orethoxy radicals, provided bythe organopolysiloxanes, from 0. 7A to 1.3A and 2) heating the whole in a temperature range from Wto 170T, in the presence of a catalyst, fora period sufficient to eliminate at most 75% of the theoretical amount of the expected alcohol (methanol and/or ethanol).

7. A modification of a composition according to anyone of claims 1 to 6, in which part of the compound A is replaced by a compound A, which is either:

a bisphenol A derivative of the formula:

ICH2=C(R)COO-CH2CH20C6H4]2C(CH3)2 in which the symbol R represents a hydrogen atom or a methyl radical, or an organopolysiloxane polymer formed of 2 to 60 mol % of units of the formula CH2=CH(R1),Si03-,12 and 98 to 40 mol % of units of the formula (R1),'Si04-,12 in which formulae the symbol R, represents a methyl or phenyl radical, the symbol g represents zero, 1 or 2, the symbol g' represents 1, 2 or 3, the molar ratio (R, + CH2=CH)/Si being from 1.4A to 2.3A and at least 5 mol % of radicals R, are phenyl radicals, the compound A, providing at most 75 mol % of the groups containing aliphatic unsaturation present in the composition.

8. A composition according to anyone of the preceding claims in which the organohydrogenopolysilox- 35 ane B is an oil having a viscosity of at most 100,000 mPa.s at 25T, and is formed of a succession of units chosen from those of the formulae: Si02, HSiOl.,, CH,(H)SiO, CH3Si011.5, (CH1)2SiO, (CH3)2HSiOo.5, (CH3)3SiOO.I, (C6H,SiOl.5, C6H5(CH3)SiO, C61- 15)2SiO, C6H5(C1-13)2Si00.5, C^(H)SiO, (C6H,)2CH3SiOO.5, distributed so as to provide the following molar ratios:

from 0.2A to 1.5A, . from 0.4A to 2: 1, H/Si from 0.1: 1 to 1: 1 and (C,H, + CH3 + H)/Si from 1.6A to 3A. 45

9. A composition according to claim 1 substantially as hereinbefore described.

10. A solid provided with a coating obtained by application to the solid of a composition as claimed in any one of the preceding claims, followed by photopolymerisation with ultraviolet radiation.

C,H5/Si CH3/Si Printed for Her Majesty's Stationery Office, by Croydon Printing Company Limited, Croydon, Surrey, 1983. Published by The Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.