Ultraviolet polymerization of acrylate monomers using oxidizable tin compounds

Claim 2

A photopolymerizable mixture comprising by weight (a) 100 parts of a composition which is polymerizable to a viscoelastic state and consists of 50-100 parts of one or both of alkyl acrylate and alkyl methacrylate and 0-50 parts of copolymerizable monoethylenically unsaturated monomer, (b) oxidizable tin salt dissolved in composition (a) in an amount providing at least 0.01 part of tin, and (c) addition-polymerization photoinitiator which is activatable by ultraviolet radiation and is dissolved in composition (a) in an amount providing about 0.01-5 parts of the photoinitiator.

Claim 3

A photopolymerizable mixture as defined in claim 1 wherein said oxidizable tin salt is a stannous salt.

Claim 4

A photopolymerizable mixture as defined in claim 1 wherein said composition (a) is polymerizable to a pressure-sensitive adhesive state.

Claim 5

A photopolymerizable mixture as defined in claim 1 wherein the composition (a) consists of a blend of (1) at least 88 parts of alkyl acrylate having 4-12 carbon atoms in its alkyl group or alkyl acrylates having an average of 4-12 carbon atoms in their alkyl groups and (2) up to 12 parts of the copolymerizable monomer, which blend copolymerizes to a pressure-sensitive adhesive state.

Claim 6

A photopolymerizable mixture as defined in claim 4 wherein at least part of the copolymerizable monomer has highly polar groups.

Claim 7

A photopolymerizable mixture as defined in claim 5 wherein the copolymerizable monomer having highly polar groups is selected from at least one member of the group consisting of acrylic acid, methacrylic acid, itaconic acid, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, N-substituted acrylamides, hydroxyalkyl acrylates, cyanoethyl acrylate, N-vinylpyrrolidone and maleic anhydride.

Claim 8

A syrup obtained by partially polymerizing a photopolymerizable mixture as defined in any of claims 1, 3, 4, 5, and 6, which syrup has a coatable viscosity of 300 to 10,000 centipoises at ordinary room temperature.

Claim 9

The polymeric product of photopolymerizing the photopolymerizable mixture of claim 1 to about 100% conversion of the acrylate unsaturation.

Claim 10

Method of making a viscoelastic material comprising exposing to ultraviolet radiation a layer of a photopolymerizable mixture as defined in claim 1.

Claim 11

Method of making a viscoelastic product comprising the steps of (1) mixing together by weight (a) 100 parts of a composition which is polymerizable to a viscoelastic state and consists of 50-100 parts of one or both of alkyl acrylate and alkyl methacrylate and 0-50 parts of copolymerizable monoethylenically unsaturated monomer, (b) oxidizable tin salt dissolved in an amount providing at least 0.01 part of tin, and (c) addition-polymerization photoinitiator which is activatable by ultraviolet radiation and is dissolved in an amount providing about 0.01-5 parts, and (2) exposing the mixture to ultraviolet radiation to photopolymerize the mixture to a viscoelastic state.

Claim 12

Method of making a viscoelastic product comprising the steps of (1) mixing together by weight (a) 100 parts of a composition which is polymerizable to a viscoelastic state and consists of 50-100 parts of one or both of alkyl acrylate and alkyl methacrylate and 0-50 parts of copolymerizable monoethylenically unsaturated monomer, (b) oxidizable tin salt dissolved in an amount providing at least 0.01 part of tin, and (c) addition-polymerization photoinitiator which is activatable by ultraviolet radiation and is dissolved in an amount providing about 0.01-5 parts, and (2) exposing the mixture to ultraviolet radiation to photopolymerize the mixture to a viscoelastic state.

Claim 13

Method of making a syrup having a coatable viscosity comprising exposing a photopolymerizable mixture as defined in claim 1 to ultraviolet radiation until the viscosity increases to 300 to 10,000 centipoises at ordinary room temperature.