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US 6,387,595 B1Granted
On-press developable lithographic printing plate having an ultrathin overcoat
OwnerGary Ganghui Tenginventor
Life of this patent
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Abstract
This invention discloses an on-press developable lithographic plate comprising on a substrate a photosensitive layer and a top ultrathin ink and/or fountain solution soluble or dispersible overcoat with a coverage of 0.001 to 0.150 g/m2. The incorporation of such an ultrathin overcoat can provide excellent white light stability, high contrast, excellent ink receptivity, and fast on-press development.
Claims20
A method of lithographically printing images on receiving media, comprising in order:
- (a) providing a lithographic printing plate comprising (i) a hydrophilic substrate;
- (ii) an oleophilic photosensitive layer capable of hardening or solubilization upon exposure to an actinic radiation, the non-hardened or solubilized areas of said photosensitive layer being soluble or dispersible ill ink and/or fountain solution;
- and (iii) an overcoat with a coverage of from 0.001 to 0.150 g/m2 which is soluble or dispersible in ink and/or fountain solution;
- (b) exposing said plate with an actinic radiation to cause hardening or solubilization of the exposed areas;
- and
- (c) contacting said exposed plate with ink and/or fountain solution on a lithographic press to remove the overcoat and the non-hardened or solubilized areas of said photosensitive layer, and to lithographically print images from said plate to the receiving media.
3 more elements
A method of lithographically printing images on receiving media, comprising in order:
- (a) providing a lithographic printing plate comprising (i) a hydrophilic substrate;
- (ii) an oleophilic photosensitive layer capable of hardening upon exposure to an actinic radiation and soluble or dispersible in ink and/or fountain solution, said photosensitive layer comprising a polymeric binder, a free radical polymerizable ethylenically unsaturated monomer or oligomer having at least one terminal ethylenic group, and a free-radical initiator;
- and (iii) a water-soluble or dispersible overcoat with a coverage of from 0.001 to 0.150 g/m2;
- (b) exposing said plate with an actinic radiation to cause hardening of the exposed areas;
- and
- (c) contacting said exposed plate with fountain solution or with both ink and fountain solution on a lithographic press to remove the overcoat and the non-hardened areas of said photosensitive layer, and to lithographically print images from said plate to the receiving media.
3 more elements
Dependencies are inferred from the claim text.