Imaging material employing photosensitive microcapsules containing tertiary amines as coinitiators

Claim 2

A photosensitive microcapsule having improved film speed comprising, as the internal phase, a photosensitive composition including a free radical addition polymerizable material, and a photoinitiator system, wherein said photoinitiator system includes an absorber, a coinitiator and an autoxidizer, said absorber, said coinitiator and said autoxidizer being different, said coinitiator being a compound which is more efficient in yielding free radicals by interacting with said absorber than said autoxidizer and said autoxidizer being more efficient in yielding free radicals by interacting with oxygen or oxygen radicals than said co-initiator, the quantum efficiency of said photosensitive composition in reacting with oxygen being substantially greater than 1, wherein said absorber is an aryl ketone, said co-initiator is an N,N-dialkylaniline represented by the formula ##STR2## wherein R 1 and R 2 are the same or different and represent an alkyl group having 1 to 6 carbon atoms or a benzyl group; and x a substituent having a Hammett's constant in the range of -0.9 to 0.7 and said autoxidizer is a thiol.

Claim 3

The photosensitive microcapsule of claim 1 wherein said microcapsule has a discrete capsule wall.

Claim 4

The photosensitive microcapsule of claim 2 wherein said free radical addition polymerizable material is an ethylenically unsaturated compound.

Claim 5

The photosensitive microcapsule of claim 1 wherein X is selected from the group consisting of a hydrogen atom, a cyano group, a halogen atom, an alkyl group, an acyl group, an alkoxy group, an amino group, a dialkylamino group, an acylamido group and an alkylsulfido group.

Claim 6

The photosensitive microcapsule of claim 4 wherein said substituents have a Hammett's σ constant in the range of -0.5 to 0.5.

Claim 7

The photosensitive microcapsule of claim 5, wherein R 1 and R 2 are methyl or ethyl.

Claim 8

The photosensitive microcapsule of claim 4 wherein X has a Hammett's constant value of -0.2 to 0.5.

Claim 9

The photosenstive microcapsule of claim 7 wherein said aryl ketone has λ max greater than about 380 nm.

Claim 10

An imaging sheet having improved film speed comprising a support having on a surface thereof a layer containing photosensitive microcapsules, said microcapsules including in the internal phase thereof a free radical addition polymerizable material, a photoinitiator system, and an image-forming agent, wherein said photoinitiator system includes an absorber, a co-initiator and an autoxidizer, said absorber, said co-initiator and said autoxidizer being different, said co-initiator being a compound which is more efficient in yielding free radicals by interacting with said absorber than said autoxidizer and said autoxidizer being more efficient in yielding free radicals be interacting with oxygen or oxygen radicals than said co-initiator, the quantum efficiency of said composition in reacting with oxygen being substantially greater than 1, wherein said absorber is an aryl ketone, said co-initiator is an N,N-dialkylaniline represented by the formula ##STR3## wherein R 1 and R 2 are the same or different and represent an alkyl group having 1 to 6 carbon atoms or a benzyl group; and x a substituent having a Hammett's constant in the range of -0.9 to 0.7 and said autoxidizer is a thiol.

Claim 11

An imaging sheet having improved film speed comprising a support having on a surface thereof a layer containing photosensitive microcapsules, said microcapsules including in the internal phase thereof a free radical addition polymerizable material, a photoinitiator system, and an image-forming agent, wherein said photoinitiator system includes an absorber, a co-initiator and an autoxidizer, said absorber, said co-initiator and said autoxidizer being different, said co-initiator being a compound which is more efficient in yielding free radicals by interacting with said absorber than said autoxidizer and said autoxidizer being more efficient in yielding free radicals be interacting with oxygen or oxygen radicals than said co-initiator, the quantum efficiency of said composition in reacting with oxygen being substantially greater than 1, wherein said absorber is an aryl ketone, said co-initiator is an N,N-dialkylaniline represented by the formula ##STR3## wherein R 1 and R 2 are the same or different and represent an alkyl group having 1 to 6 carbon atoms or a benzyl group; and x a substituent having a Hammett's constant in the range of -0.9 to 0.7 and said autoxidizer is a thiol.

Claim 12

The imaging sheet of claim 9 wherein said microcapsule has a discrete capsule wall.

Claim 13

The imaging sheet of claim 10 wherein said free radical addition polymerizable material is an ethylenically unsaturated compound.

Claim 14

The imaging sheet of claim 9 wherein X is selected from the group consisting of a hydrogen atom, a cyano group, a halogen atom, an alkyl group, an acyl group, an alkoxy group, an amino group, a dialkylamino group, an acylamido group and an alkylsulfide group.

Claim 15

The imaging sheet of claim 12, wherein R 1 and R 2 are methyl or ethyl.

Claim 16

The imaging sheet of claim 9 wherein X is a substituent having a Hammett's constant of -0.2 to 0.5.

Claim 17

The imaging sheet of claim 11 wherein said aryl ketone has λ max greater than about 380 nm.

Claim 18

The imaging sheet of claim 14 wherein said image forming agent is a substantially colorless electron donating compound.

Claim 19

The photosensitive microcapsule of claim 1 wherein said internal phase additionally includes a substantially colorless electron donating compound.

Claim 20

The photosensitive microcapsule of claim 1, wherein said thiol is selected from the group consisting of 2-mercaptobenzothiazole, 6-ethoxy-2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 4-methyl-4H-l,2,4-triazole-3-thiol, 2-mercapto-l-methylimidazole, 2-mercapto-5-methylthio-1,3,4-thiadiazole 5-n-butylthio-2-mercapto-1,3,4-thiadiazole,- 4-methoxybenzenethiol, 1-phenyl-1H-tetrazole-5-thiol, 4-phenyl-4H-l,2,4-triazole-3-thiol, 2-mercaptobenzimidazole, pentaerythritol tetrakis(mercaptoacetate), pentaerythritol tetrakis(3-mercapt-opropionate), trimethylolpropane tris(mercaptoacetate), trimethylolpropane tris(3-mercaptopropionate), 4-acetamidothiophenol, mercaptosuccinic acid, dodecanethiol, 2-mercaptopyridine, 4-mercaptopyriding, 2-mercapto-3H-quinazoline, and 2-mercaptothiazoline.

Claim 21

The photosensitive microcapsule of claim 1, wherein said aryl ketone is selected from the group consisting of benzophenone, 4,4'-dimethoxybenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bis(dimethylamino) benzophenone, benzanthone, 9-fluorenone, xanthone, 2-methylxanthone, 2-dodecylxanthone, thioxanthone, 2-methylthioxanthone, 2-dodecylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, and 3-cinnamoyl-7-diethylaminocoumarin.

Claim 22

The photosensitive microcapsule of claim 19, wherein said coinitiator is ethyl p-dimethylaminobenzoate.

Claim 23

The photosensitive microcapsule of claim 19, wherein said autoxidizer is N,N,2,4,6-pentamethylaniline.

Claim 24

The photosensitive microcapsule of claim 19, wherein said autoxidizer is 2,6-diethyl-N,N-dimethylaniline or 2,6-diisopropyl-N,N-dimethylaniline.

Claim 25

The photosensitive microcapsule of claim 1 wherein said photoinitiator system consists essentially of said absorber, said co-initiator, and said autooxidizer.

Claim 26

The imaging sheet of claim 9 wherein said photoinitiator system consists essentially of said absorber, said co-initiator, and aid autooxidizer.