Ultraviolet polymerization of acrylate monomers using oxidizable tin compounds

Claim 2

Pressure-sensitive adhesive tape comprising a backing member and a photopolymerized pressure-sensitive adhesive coating of a mixture comprising by weight (a) 100 parts of a composition which is polymerizable to a pressure-sensitive adhesive 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 pressure-sensitive adhesive tape as defined in claim 1 wherein said oxidizable tin salt is a stannous salt.

Claim 4

A pressure-sensitive adhesive tape 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.

Claim 5

A pressure-sensitive adhesive tape as defined in claim 3 wherein at least part of the copolymerizable monomer has highly polar groups.

Claim 6

A pressure-sensitive adhesive tape as defined in claim 4 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 7

Method of making a pressure-sensitive adhesive tape comprising the steps of (1) preparing a syrup of coatable viscosity from a mixture of (a) 100 parts of a composition which is polymerizable to a pressure-sensitive adhesive 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, (2) coating said syrup onto a backing member to provide a layer having a thickness of about 25-250 micrometers, and (3) in an inert atmosphere, irradiating the coating with ultraviolet radiation to polymerize it to a pressure-sensitive adhesive state.

Claim 8

Method of making a pressure-sensitive adhesive tape comprising the steps of (1) preparing a syrup of coatable viscosity from a mixture of (a) 100 parts of a composition which is polymerizable to a pressure-sensitive adhesive 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, (2) coating said syrup onto a backing member to provide a layer having a thickness of about 25-250 micrometers, and (3) in an inert atmosphere, irradiating the coating with ultraviolet radiation to polymerize it to a pressure-sensitive adhesive state.

Claim 9

Method as defined in claim 6 wherein step (1) involves the step of exposing said mixture to ultraviolet radiation to provide a partially-polymerized syrup having a viscosity of 300 to 10,000 centipoises at ordinary room temperature.