Dual curable silicone compositions

A silicone polymer substituted with both hydrolyzable leaving groups and epoxy groups is catalyzed with condensation cure catalyst and onium salt photoinitiator to produce a dual curable composition.

What is claimed is:

1. A composition comprising

(A) a dual curable silicone polymer containing units of the formula:

R.sub.A R.sub.B.sup.1 R.sub.C.sup.2 SiO.sub.(4-A-B-C)/2

wherein R is hydrogen or a substituted or unsubstituted C.sub.(1-18) hydrocarbon; R.sup.1 is or contains a hydrolyzable leaving group; R.sup.2 is a C.sub.(1-18) epoxy functional substituted or unsubstituted hydrocarbon; "A" is 0 or 1, "B" is 1 or 2, "C" is 1 or 2 and A+B+C is 2 or 3;

(B) a catalytic amount of onium salt photocatalyst; and

(C) a catalytic amount of condensation cure catalyst;

wherein the silicone polymer is prepared by reacting in the presence of dibutylammonium formate (1) a functional silane having the formula:

R.sub.A R.sub.D.sup.1 R.sub.C.sup.2 Si

wherein R is hydrogen or a substituted or unsubstituted C.sub.(1-18) hydrocarbon, R.sup.1 is a hydrolyzable leaving group, R.sup.2 is a C.sub.(1-18) epoxy functional hydrocarbon, A is 0 or 1, D is 2 or 3, C is 1 or 2, and A+D+C is 4; and (2) is hydroxy stopped polydiorganosiloxane of the formula:

HO--(R.sub.2 SiO).sub.x --H

wherein x is selected to produce a viscosity between about 10 and about 10,000,000 centipoise at 25.degree. C. and R is hydrogen or substituted or unsubstituted C.sub.(1-18) hydrocarbon.

2. The composition of claim 1 wherein said dual curable silicone polymer is linear having terminal siloxane units of the formula

R.sub.2.sup.1 R.sup.2 SiO.sub.178 or

[R.sub.2 R.sup.2 SiO]R.sub.2.sup.1 SiO.sub.178

3. The composition of claim 1 wherein said R.sup.1 is independently, alkoxy, acyloxy, amide, amino, carbamato, enoxy, imidato, isocyanato, oximato, thioisocyanato or ureido.

4. The composition of claim 1 wherein said R.sup.2 is glycidyl or cyclohexyl epoxy.

5. The composition of claim 1 wherein R.sup.2 is joined to said dual curable silicone polymer by an Si-C bond.

6. The composition of claim 1 wherein R.sup.2 has the formula:

--R.sup.5 --Q.sub.d --R.sup.E

where R.sup.5 is a C.sub.(1-16) substituted or unsubstituted hydrocarbon, Q is siloxane, ether, amide, ester, thioether, or imide, R.sup.E is a C.sub.(2-16) substituted or unsubstituted epoxy functional hydrocarbon, and "d" is 0 or 1.

7. The composition of claim 1 wherein said dual curable silicone polymer is the endcapping reaction product of

HO--(R.sub.2 SiO).sub.X --H

where R is given above and "X" is selected to produce a viscosity of about 10 to about 10,000,000 centipoise, and

R.sub.A R.sub.D.sup.1 R.sub.C.sup.2 SiO

where R, R.sup.1 and R.sup.2 are given above, "A" is 0 or 1, "D" is 2 or 3, "C" is 1or 2, and A+D+C is 4.

8. The composition of claim 1 wherein said dual curable silicone polymer is a fluid gum or resin.

9. The composition of claim 1 wherein said onium salt photocatalyst is halonium salt, sulfonium salt or phosphonium salt.

10. The composition of claim 1 wherein said onium salt photocatalyst is present in an amount of from about 0.1 to about 10% by weight based on dual curable composition.

11. The composition of claim 1 wherein said condensation cure catalyst is a tin compound, titanium compound or zirconium compound, or Bronsted acid.

12. The composition of claim 1 wherein said condensation cure catalyst is present in an amount of from about 0.001 to about 1% by weight based on dual curable composition.

13. A composition exposed to sufficient UV light to render the same tack free, said composition comprising:

(A) a dual curable silicone polymer containing units of the formula:

R.sub.A R.sub.B.sup.1 R.sub.C.sup.2 SiO.sub.(4-A-B-C)/2

wherein R is hydrogen or a substituted or unsubstituted C.sub.(1-18) hydrocarbon; R.sup.1 is or contains a hydrolyzable leaving group; R.sup.2 is a C.sub.(1-18) epoxy functional substituted or unsubstituted hydrocarbon; "A" is 0 or 1, "B" is 1 or 2, "C" is 1 or 2 and A+B+C is 2 or 3;

(B) a catalytic amount of onium salt photocatalyst; and

(C) a catalytic amount of condensation cure catalyst;

wherein the silicone polymer is prepared by reacting in the presence of dibutylammonium formate (1) a functional silane having the formula:

R.sub.A R.sub.D.sup.1 R.sub.C.sup.2 Si

wherein R is hydrogen or a substituted or unsubstituted C.sub.(1-18) hydrocarbon, R.sup.1 is a hydrolyzable leaving group, R.sup.2 is a C.sub.(1-18) epoxy functional hydrocarbon, A is 0 or 1, D is 2 or 3, C is 1 or 2, and A+D+C is 4; and (2) is hydroxy stopped polydiorganosiloxane of the formula:

HO--(R.sub.2 SiO).sub.x --H

wherein x is selected to produce a viscosity between about 10 and about 10,000,000 centipoise at 25.degree. C. and R is hydrogen or substituted or unsubstituted C.sub.(1-18) hydrocarbon.