Inhibited precious metal catalyzed organopolysiloxane compositions

Claim 2

A curable composition comprising: (a) an organopolysiloxane base polymer comprising an olefinorganopolysiloxane having structural units of the formula: ##EQU3## where R is an organic radical and R 1 is an olefinic radical, a has a value ranging from 0 to 3, b has a value ranging from about 0.005 to about 2.0, the sum of a+b ranging from about 0.8 to 3, and the viscosity of said olefinogranopolysiloxane ranging from about 10 centipoise to about 250,000,000 centipoise at 25° C.; (b) an organohydrogenpolysiloxane crosslinking agent; (c) an effective amount of precious metal containing catalyst; and (d) an azo compound wherein at least one --N═N-- moiety is not part of a cyclic structure, in an amount effective to inhibit reaction of said organopolysiloxane base polymer and said organohydrogenpolysiloxane crosslinking agent.

Claim 3

A composition as in claim 1, wherein the azo compound has the general formula R--N═N--R where each R is an independently selected organic radical which may contain hetero atoms selected from the group consisting of oxygen, sulfur and nitrogen.

Claim 4

A composition as in claim 1, wherein the azo compound contains an electron withdrawing group bonded to the --N═N-- moiety.

Claim 5

A composition as in claim 3, wherein the azo compound has the general formula R--X--N═N--X--R where each R is an independently selected organic radical which may contain hetero atoms selected from the group consisting of oxygen, sulfur and nitrogen, and X is an electron withdrawing group.

Claim 6

A composition as in claim 4, wherein X is carbonyl.

Claim 7

A composition as in claim 3, wherein the azo compound has the general formula ##STR4## where each R 1 is an independently selected C 1-6 hydrocarbon radical.

Claim 8

A composition as in claim 6, wherein the azo compound is selected from the group consisting of diethylazodicarboxylate and diisopropylazodicarboxylate.

Claim 9

A composition as in claim 1, wherein the azo compound is present in an amount of from 0.005 weight percent to 2 weight percent.

Claim 10

A composition as in claim 6, wherein the azo compound is present in an amount of from 0.01 weight percent to 0.5 weight percent.

Claim 11

A composition as in claim 1, wherein R is selected from the group consisting of monovalent hydrocarbon radicals, halogenated monovalent hydrocarbon radicals and cyanoalkyl radicals, R 1 is selected from the group consisting of vinyl, allyl, acrylate and methacrylate, and mixtures thereof, and the viscosity ranges from 50 centipoise to 1,000,000 centipoise at 25° C.

Claim 12

A composition as in claim 10, wherein the viscosity ranges from 100 centipoise to 100,000 centipoise at 25° C.

Claim 13

A composition as in claim 1, wherein the precious metal catalyst is a platinum containing catalyst.

Claim 18

A method as in claim 14, wherein curing is initiated by exposing the coated substrate to an effective amount of ultraviolet radiation.

Claim 19

A method as in claim 14, wherein curing is initiated by exposing the coated substrate to an elevated temperature.

Claim 20

A method as in claim 15, wherein the substrate is heat sensitive.

Claim 21

A method as in claim 17, wherein the substrate is a plastic having a low melting point.

Claim 22

A method as in claim 17, wherein the substrate is an electronic component.

Claim 23

A curable composition comprising: (a) a polysiloxane having the general formula: ##STR5## where each R is independently selected from substituted or unsubstituted monovalent hydrocarbon radicals having from 1 to 20 carbon atoms; R 1 is hydrogen, hydroxyl, or a substituted or unsubstituted hydrocarbon or hydrocarbonoxy radical having from 1 to 20 carbon atoms; R 2 is an olefinic radical; x is a number such that there is present from about 0.1 to about 20 mole percent olefin-containing siloxy units; y is a number such that there is present from about 0.5 to about 50 mole percent hydrogen-containing siloxy units; and x+y+z is a number such that the viscosity of said polysiloxane is from about 25 centipoise to about 2,500,000 centipoise at 25° C.; (c) an effective amount of precious metal containing catalyst; and (d) an azo compound wherein at least one --N═N-- moiety is not part of a cyclic structure, in an amount effective to inhibit reaction of said polysiloxane.

Claim 24

A curable composition comprising: (a) a polysiloxane having the general formula: ##STR5## where each R is independently selected from substituted or unsubstituted monovalent hydrocarbon radicals having from 1 to 20 carbon atoms; R 1 is hydrogen, hydroxyl, or a substituted or unsubstituted hydrocarbon or hydrocarbonoxy radical having from 1 to 20 carbon atoms; R 2 is an olefinic radical; x is a number such that there is present from about 0.1 to about 20 mole percent olefin-containing siloxy units; y is a number such that there is present from about 0.5 to about 50 mole percent hydrogen-containing siloxy units; and x+y+z is a number such that the viscosity of said polysiloxane is from about 25 centipoise to about 2,500,000 centipoise at 25° C.; (c) an effective amount of precious metal containing catalyst; and (d) an azo compound wherein at least one --N═N-- moiety is not part of a cyclic structure, in an amount effective to inhibit reaction of said polysiloxane.