Extensible and pasteurizable radiation curable coating for metal containing organofunctional silane adhesion promoter

Claim 2

A radiation-curable coating composition for application as a coating to a metal surface which is to be subsequently subjected to a metal working step, said composition consisting essentially of: (a) from about 15% to about 75% by weight of at least one ethylenically unsaturated bulky monomer of the formula ##STR3## wherein R 1 is selected from the group consisting of H and CH 3 , and wherein R 2 is a substituent selected from the group consisting of isobornyl, dicyclopentenyl, dicyclopentenyl oxyethyl, cyclohexyl, 3,3,5-trimethyl cyclohexyl, phenyl, benzyl, naphthyl, substituted derivatives thereof, and mixtures thereof, said bulky monomer being characterized such that, when cured to form a homopolymer, shrinkage does not exceed 15%; (b) from about 10% to about 80% by weight of an oligomeric component comprising a mixture of (i) at least one of a urethne acrylate oligomer or urethne methacrylate oligomer and (ii) at least one of an epoxy acrylate oligomer or epoxy methacrylate oligomer; said oligomeric component comprising at least 10% by weight of each of said (i) and (ii) oligomers based on the weight of said mixture; and (c) from a small but effective amount up to about 10% by weight of an organofunctional silane adhesion promoter; said components (a) and (b) being copolymerizable upon curing of said composition, and said percentages being based on the combined weight of (a) plus (b) plus (c), and wherein said composition, after application to a metal surface, is curable to form a coating on said metal surface that is characterized by having a shrinkage of not more than 15% and an elongation at break, upon or working of the metal, of at least 5%.

Claim 3

A composition according to claim 1 wherein oligomer mixture (b) additionally comprises (iii) at least one of a polyester acrylate oligomer or polyester methacrylate oligomer.

Claim 4

A composition in accordance with claim 1, wherein the organofunctional silane adhesion promoter (c) contains ethylenic unsaturation.

Claim 5

A composition according to claim 1 that is curable by ultraviolet radiation and that further comprises an effective amount of a photoinitiator.

Claim 6

A composition according to claim 4 that further comprises an effective amount of a coinitiator.

Claim 7

A composition according to claim 5 wherein the coinitiator contains an amino functional group.

Claim 8

A composition according to claim 1 wherein said metal surface is the external surface of a can cup and wherein said cured coating remains bonded to metal surface subsequent to die necking and spin necking.

Claim 9

In a process for preparing a coated metal can cup for producing a can suitable for beverage use comprising shaping metal sheet into a cylindrical can cup suitable for finishing into a can; washing said can cup in alkaline and acid baths; drying said cup; applying a coating to the surface of said can cup; reducing the diameter of one end of said can in a die necking process to form a die necked end; and tapering said die necked end in a spin necking process, the improvement comprising applying to the surface of said can cup the radiation curable coating composition of claim 1 and curing said coating by radiation prior to said die necking and spin necking processes, said improvement being characterized by the fact that said cured coating essentially maintains its bond to the metal surface during and subsequent to said die necking and spin necking processes.

Claim 10

The process of claim 8 comprising, as an additional step, subjecting the coated, worked article to pasteurization, said cured coating maintaining its bond to the article during and subsequent to said pasteurization step.

Claim 11

A composition of claim 1 wherein said bulky monomer is present in an amount of from about 1/3 to 2/3 by weight.

Claim 12

A composition of claim 10 wherein said bulky monomer is present in an amount of from about 40% to about 60% by weight.

Claim 13

A composition of claim 11 wherein said bulky monomer is present in an amount of from about 53% to about 58% by weight.

Claim 14

A composition of claim 1 wherein R 2 is isobornyl.

Claim 15

A radiation curable coating composition for application to a metal surface which is to be subsequently subjected to a metal working step, said composition consisting essentially of: (a) from about 1/3 to about 2/3 by weight of at least one ethylenically unsaturated bulky monomer of the formula ##STR4## wherein R 1 is selected from the group consisting of H and CH 3 , and wherein R 2 is selected from the group consisting of isobornyl, dicyclopentenyl, dicyclopentenyl oxyethyl, cyclohexyl, 3,3,5-trimethyl cyclohexyl, phenyl, benzyl, naphthyl, substituted derivatives thereof, and mixtures thereof; (b) from about 20% to about 60% by weight of an oligomeric component comprising a mixture of (i) at least one of a urethane acrylate oligomer or urethane methacrylate oligomer; and (ii) at least one of an epoxy acrylate oligomer or epoxy methacrylate oligomer; said oligomeric component comprising at least 10% by weight of each of said (i) and (ii) oligomers based on the weight of said mixture; and (c) from about 0.1% to about 10% by weight of an organofunctional silane adhesion promoter selected from the group consisting of vinyltrichlorosilane; methyltrichlorosilane; methyldichlorosilane; dimethyldichlorosilane, methylvinyldichlorosilane, methyltriethoxysilane; methyltrimethoxysilane; vinyltriethoxysilane; vinyltrimethoxysilane; vinyl-tris-(2-methoxyethoxysilane); vinyltriacetoxysilane; gamma-methacryloxylpropyltrimethoxysilane; gamma-methacryloxypropyl-tris-(2-methoxyethoxy)silane; beta-(3,4-epoxycyclohexyl)ethyl-trimethoxysilane; gamma-glycidoxypropyltrimethoxysilane; gamma-mercaptopropyltriethoxysilane; gamma-mercaptopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane; gamma-aminopropyltrimethoxysilane; N-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane, triaminofunctional silane; gamma-ureidopropyltriethoxysilane; N-(2-aminoethyl)-3-amino-propyltrimethoxysilane; N-[2-(vinylbenzylamino)-ethyl]-3-aminopropyltrimethoxysilane and 3-chloropropyltrimethoxysilane, said (a) and (b) components being copolymerizable upon radiation curing of said composition, and said percentages being based on the combined weight of (a) plus (b) plus (c), and wherein said composition, after application to a metal surface, is curable to form a coating on said metal surface that is characterized by having a shrinkage of not more than 15% and an elongation at break, upon or working of the metal, of at least 5%.

Claim 16

A radiation curable coating composition for application to a metal surface which is to be subsequently subjected to a metal working step, said composition consisting essentially of: (a) from about 1/3 to about 2/3 by weight of at least one ethylenically unsaturated bulky monomer of the formula ##STR4## wherein R 1 is selected from the group consisting of H and CH 3 , and wherein R 2 is selected from the group consisting of isobornyl, dicyclopentenyl, dicyclopentenyl oxyethyl, cyclohexyl, 3,3,5-trimethyl cyclohexyl, phenyl, benzyl, naphthyl, substituted derivatives thereof, and mixtures thereof; (b) from about 20% to about 60% by weight of an oligomeric component comprising a mixture of (i) at least one of a urethane acrylate oligomer or urethane methacrylate oligomer; and (ii) at least one of an epoxy acrylate oligomer or epoxy methacrylate oligomer; said oligomeric component comprising at least 10% by weight of each of said (i) and (ii) oligomers based on the weight of said mixture; and (c) from about 0.1% to about 10% by weight of an organofunctional silane adhesion promoter selected from the group consisting of vinyltrichlorosilane; methyltrichlorosilane; methyldichlorosilane; dimethyldichlorosilane, methylvinyldichlorosilane, methyltriethoxysilane; methyltrimethoxysilane; vinyltriethoxysilane; vinyltrimethoxysilane; vinyl-tris-(2-methoxyethoxysilane); vinyltriacetoxysilane; gamma-methacryloxylpropyltrimethoxysilane; gamma-methacryloxypropyl-tris-(2-methoxyethoxy)silane; beta-(3,4-epoxycyclohexyl)ethyl-trimethoxysilane; gamma-glycidoxypropyltrimethoxysilane; gamma-mercaptopropyltriethoxysilane; gamma-mercaptopropyltrimethoxysilane, gamma-aminopropyltriethoxysilane; gamma-aminopropyltrimethoxysilane; N-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane, triaminofunctional silane; gamma-ureidopropyltriethoxysilane; N-(2-aminoethyl)-3-amino-propyltrimethoxysilane; N-[2-(vinylbenzylamino)-ethyl]-3-aminopropyltrimethoxysilane and 3-chloropropyltrimethoxysilane, said (a) and (b) components being copolymerizable upon radiation curing of said composition, and said percentages being based on the combined weight of (a) plus (b) plus (c), and wherein said composition, after application to a metal surface, is curable to form a coating on said metal surface that is characterized by having a shrinkage of not more than 15% and an elongation at break, upon or working of the metal, of at least 5%.

Claim 17

A radiation curable coating composition according to claim 14, wherein said organofunctional silane adhesion promoter is selected from gamma-aminopropyltriethoxysilane, gamma-methacryloxypropyltrimethoxysilane, and glycidoxypropyltrimethoxysilane.

Claim 18

The composition of claim 14 wherein the oligomer mixture (b) additionally comprises (iii) at least one of a polyester acrylate oligomer or polyester methacrylate oligomer.

Claim 19

The composition of claim 14 that is curable by ultraviolet radiation and that further comprises an effective amount of a photoinitiator.

Claim 20

A composition according to claim 17 that further comprises an effective amount of a coinitiator.

Claim 21

A composition according to claim 17 wherein the coinitiator contains an amino functional group.

Claim 22

The composition of claim 14 wherein said metal surface is the external surface of a can cup and wherein said cured coating remains bonded to said metal surface subsequent to die necking and spin necking.

Claim 23

The composition of claim 14 wherein said metal surface is the exterior surface of a can cup and wherein said coating, after curing, remains bonded to said surface following pasteurization thereof.

Claim 24

The radiation curable coating composition of claim 21 wherein said organofunctional silane adhesion promoter comprises gamma-aminopropyltriethoxy silane.

Claim 25

The radiation curable coating composition of claim 21 wherein said organofunctional silane adhesion promoter is gamma-methacryloxypropyltrimethoxysilane.

Claim 26

The composition of claim 14 that is essentially free of volatile organic solvent, that is curable by ultraviolet radiation and that further comprises an effective amount of a photoinitiator and coinitiator, and that, after application to a metal surface as a coating thereon, is curable to form a cured coating that is characterized by having a shrinkage of not more than 15% and an elongation at break upon deformation or working of the metal, of at least 5%, wherein said metal surface is the external surface of a can cup and wherein said cured coating remains bonded to said metal surface subsequent to die necking, spin necking, and pasteurization.

Claim 27

The composition of claim 24 further comprising small but effective amounts of a polyethylene wax and a particulate polytetrafluoroethylene wax both for imparting characteristics of abrasion resistance and slip to the coating upon curing, a small but effective amount of an acrylated silicone for improving the characteristics of flow out and slip of the coating upon curing, and a small but effective amount of an acrylated fluorocarbon for improved wetting ability of the coating prior to curing and improved water resistance.

Claim 28

The composition of claim 36 further comprising up to about 15% by weight based on the total composition of an extender resin that does not impair the ability of the ethylenically unsaturated components to copolymerize and does not impair the functional characteristics of the coating upon curing.

Claim 29

The composition of claim 26 wherein said extender resin is a chlorinated paraffin.

Claim 30

The radiation curable coating composition of claim 14 wherein said ethylenically unsaturated bulky monomer comprises isobornyl acrylate.

Claim 31

The radiation curable coating composition of claim 14 wherein said ethylenically unsaturated bulky monomer comprises dicyclopentenyl acrylate.

Claim 32

The radiation curable coating composition of claim 14 wherein said mixture of oligomers (b) comprises a mixture of from about 10% to about 90% by weight of an acrylated epoxy oligomer, from about 10% to about 90% by weight of an acrylated aliphatic urethane oligomer, and from about 5% to about 50% by weight of an acrylated polyester oligomer, wherein said percentages are based on the weight of said mixture of oligomers.

Claim 33

The composition of claim 14 further comprising a small but effective amount of a polyethylene wax for imparting abrasion resistance and slip to said cured coating upon curing.

Claim 34

The composition of claim 14 further comprising a small but effective amount of a particulate polytetrafluoroethylene wax for imparting abrasion resistance and slip to said coating upon curing.

Claim 35

The composition of claim 14 further comprising a small but effective amount of silicone diacrylate for imparting improved flow-out and slip characteristics to said coating upon curing.

Claim 36

The composition of claim 14 further comprising up to 15% by weight of the total weight of the composition of an extender resin that does not impair the copolymerization of the other materials upon curing nor the functional characteristics of the cured coating.

Claim 37

A composition of claim 14 wherein said bulky monomer is present in an amount of from about 40% to about 60% by weight.

Claim 38

A composition of claim 35 wherein said bulky monomer is present in an amount of from about 53% to about 58% by weight.

Claim 39

A composition of claim 14 wherein R 2 is isobornyl.

Claim 40

A radiation curable coating composition for metal containers consisting essentially of: (a) from about 40% to about 60% by weight of isobornyl acrylate; (b) from about 1% to about 72% by weight of a urethane acrylate oligomer; (c) from about 1% to about 72% by weight of an epoxy acrylate oligomer; (d) from about 0.05% to about 40% by weight of a polyester acrylate oligomer; (e) from about 0.25% to about 2% by weight based on the total composition above of an organofunctional silane; (f) from about 5 to about 7 parts by weight of a photoinitiator; (g) from about 1 to about 10 parts by weight of a coinitiator; (h) from about 1 to about 3 parts by weight of silicone diacrylate; (i) from about 1 to about 3 parts by weight of polyethylene wax; (j) from about 0.5 to about 1 part by weight of finely divided polytetrafluoroethylene; and (k) up to about 15 parts by weight of a chlorinated paraffin extender resin; said parts by weight being per 100 parts by weight of the combined weight of (a), (b), (c) and (e).

Claim 41

A radiation curable coating composition for metal containers consisting essentially of: (a) from about 40% to about 60% by weight of isobornyl acrylate; (b) from about 1% to about 72% by weight of a urethane acrylate oligomer; (c) from about 1% to about 72% by weight of an epoxy acrylate oligomer; (d) from about 0.05% to about 40% by weight of a polyester acrylate oligomer; (e) from about 0.25% to about 2% by weight based on the total composition above of an organofunctional silane; (f) from about 5 to about 7 parts by weight of a photoinitiator; (g) from about 1 to about 10 parts by weight of a coinitiator; (h) from about 1 to about 3 parts by weight of silicone diacrylate; (i) from about 1 to about 3 parts by weight of polyethylene wax; (j) from about 0.5 to about 1 part by weight of finely divided polytetrafluoroethylene; and (k) up to about 15 parts by weight of a chlorinated paraffin extender resin; said parts by weight being per 100 parts by weight of the combined weight of (a), (b), (c) and (e).

Claim 42

The composition of claim 38 wherein said metal surface is the external surface of a can cup and wherein said cured coating remains bonded to said metal surface subsequent to die necking and spin necking.

Claim 43

In a process for preparing a coated metal can cup for producing a can suitable for beverage use comprising applying a coating to the external surface of said can cup; subjecting the coated can to mechanical working in a die necking and/or spin necking process, the improvement comprising applying to the surface of said can cup the radiation curable coating composition of claim 38 and curing said coating by radiation prior to said die necking and spin necking processes, improvement being characterized byy the fact that said cured coating essentially maintains its bond to the metal surfaces during and subsequent to mechanical working.

Claim 44

In a process for preparing a coated metal can cup for producing a can suitable for beverage use comprising applying a coating to the external surface of said can cup and subjecting the coated can to mechanical working in a die necking and/or spin necking process, the improvement comprising applying to the surface of said cna cup the radiation curable coating composition of claim 1 and curing said coating by radiation prior to said die necking and spin necking processes said improvement being characterized by the fact that said cured coating essentially maintains its bond to the metal surface during and subsequent to said mechanical working.

Claim 45

The process of claim 41 comprising, as an additional step, subjecting the coated, worked can to pasteurization, said cured coating maintaining its bond to the can during and subsequent to said pasteurization step.

Claim 46

A coated metal can prepared according to the process of claim 41.