Presensitized light-sensitive letterpress printing makeready

Claim 2

selectively developing said light-exposed sheet material in an imagewise manner to remove developable areas of (c);

Claim 3

exposing said developed sheet material to uniform high-intensity radiant energy, said radiant energy being differentially absorptive in image areas commensurate with the tonal density of said image areas, said radiant energy providing a heat pattern sufficient to selectively expand said sheet material in accordance with said heat pattern at least 2 mils greater than the initial thickness thereof.

Claim 4

The article of claim 2 in which the selectively thermoexpansible layer contains a curing agent for said thermosetting resin.

Claim 5

The article of claim 2 in which the selectively thermoexpansible layer is at least about 3 mils thick and contains an organic plasticizer.

Claim 6

The article of claim 1 wherein said light sensitive material comprises one or more photopolymerizable monomers and a photoinitiator capable of forming free radicals when exposed to actinic light.

Claim 7

A presensitized, light-sensitive, flexible sheet material of essentially uniform thickness adaptable for makeready in letterpress printing, said sheet material comprising a. a flexible carrier web; b. a selectively thermoexpansible layer at least 2 mils thick overlying said carrier web, comprising a thermoplastic resin, a thermosetting resin, and a curing agent for said thermosetting resin, and uniformly distributed therethrough a normally dormant, heat-sensitive puffing agent activatable at a temperature well above room temperature to expand said layer under conditions of heat, said puffing agent being present in an amount sufficIent to provide on rapid and complete heat activation of said layer an increase of at least 2 mils in the thickness thereof; c. a light-sensitive layer overlying said thermoexpansible layer and in direct contact therewith, comprising light-sensitive material having one solubility state in relation to a developing media before exposure to light and another solubility state in relation to said developing media after exposure to light, said light-sensitive material being soluble in one of said states and insoluble in its other state, said layer further comprising a polymeric film-forming binder resin having uniformly distributed therethrough a finely divided pigment, said layer being selectively removable from said underlying thermoexpansible layer in areas wherein said light-sensitive material is in its soluble state, said layer being absorptive of high-intensity radiant energy and firmly bonded to said underlying thermoexpansible layer in areas wherein said light-sensitive material is in its insoluble state said sheet material in expanded condition being capable of supporting of at least on the order of 250 pounds per square inch for about 15 seconds while maintaining areas of maximum expansion at least approximately 2 mils greater than the initial thickness thereof.

Claim 8

The article of claim 6 wherein said finely divided pigment is carbon black.

Claim 9

A process of preparing a makeready sheet suitable for letterpress printing comprising: a. exposing to actinic light through a photographic negative or positive transparency a light-sensitive flexible sheet material comprising: a. a flexible carrier web; b. a selectively thermoexpansible layer at least 2 mils thick overlying said carrier web, comprising an at least temporarily thermosoftenable resinous material, and uniformly distributed therethrough a normally dormant, heat-sentive puffing agent activable at a temperature well above room temperature to expand said layer under conditions of heat, said puffing agent being present in an amount sufficient to provide on rapid and complete heat activation of said layer an increase of at least 2 mils in the thickness thereof; c. a light-sensitive layer overlying said thermoexpansible layer and in direct contact therewith, comprising light-sensitive material having one solubility state in relation to a developing media before exposure to light and another solubility state in relation to said developing media after exposure to light, said light-sensitive material being soluble in one of said states and insoluble in its other state, said layer further comprising a polymeric film-forming binder resin having uniformly distributed therethrough a finely divided pigment, said layer being selectively removable from said underlying thermoexpansible layer in areas wherein said light-sensitive material is in its soluble state, said layer being absorptive of high-intensity radiant energy and firmly bonded to said underlying thermoexpansible layer in areas wherein said light-sensitive material is in its insoluble state said sheet material in expanded condition being capable of supporting of at least on the order of 250 pounds per square inch for about 15 seconds while maintaining areas of maximum expansion at least approximately 2 mils greater than the initial thickness thereof.