Lithographic printing plate for in-solidus development on press
View Patent ↗A printing plate having a substrate and a radiation sensitive, negative working, organic, polymerizable, photosensitive (PS) resin coating non-ionically adhered to the substrate such that the cohesion of the PS coating exceeds the adhesion of the PS coating to the substrate. The PS coating contains active components that participate in radiation induced polymerization, all of which active components are soluble in non-aqueous solvents and none of which active components are soluble or dispersible in any of the group of fluids consisting of water, fountain solution, ink, and press ink. The PS coating has sufficient cohesion and surface tack to adhere to and be mechanically pulled off the substrate by press ink as particulates without dissolution or dispersion into the press ink.
1. A printing plate having a photosensitive (PS) coating to be radiation imaged and developed for printing on a lithographic press, comprising:
a substrate with a grained, anodized, hydrophilic surface; and
a radiation sensitive, negative working, organic, polymerizable PS resin coating non-ionically adhered to the substrate such that the cohesion of the PS coating exceeds the adhesion of the PS coating to the substrate;
wherein the PS coating contains active components that participate in radiation induced polymerization, all of which active components are soluble in non-aqueous solvents and none of which active components are soluble or dispersible in any of the group of fluids consisting of water, fountain solution, ink, and press ink; and
wherein said PS coating has sufficient cohesion and surface tack to adhere to and be mechanically pulled off the substrate by press ink as particulates without dissolution or dispersion into the press ink.
2. The printing plate of claim 1 , wherein the active components of the PS coating before imaging, include a polymer and multi functional monomer and/or oligomer.
3. The printing plate of claim 1 , wherein the active components of the PS coating include an organo-borate catalyst with one of a triazine or an onium salt catalyst.
4. The printing plate of claim 1 , wherein the resin in said resin coating is selected from the group consisting of poly vinyls, cellulosic, epoxies, and acrylics.
5. The printing plate of claim 2 , wherein the monomer and/or oligomer is selected from the group consisting of polyester, polyether, epoxy, urethane acrylates, and methacrylates.
6. The printing plate of claim 1 , wherein
the PS coating comprises a urethane acrylate resin; and
the active components of the PS coating include an organo-borate catalyst with one of a triazine or an onium salt catalyst.
7. The printing plate of claim 1 , including a top coat of a water soluble oxygen barrier.
8. The printing plate of claim 2 , wherein
the resin in said resin coating is a polymer selected from the group consisting of acrylates, siloxanes, and styrene maleic anhydrides; and
the monomer is a multifunctional acrylate.
9. The printing plate of claim 1 , wherein the active components include,
from about 5 to about 30 wt % based on solids content, of a urethane acrylate resin;
from about 35 to about 75 wt % based on solids content, of a radically polymerizable, multifunctional acrylate monomer and/or oligomer; and
an initiator system capable of initiating a polymerization reaction upon exposure to imaging radiation.
10. The printing plate of claim 1 , wherein none of any components of the PS coating is soluble in press ink or fountain water.
11. The printing plate of claim 10 , wherein the coating components include a pigment dispersion, a stabilizer, an IR dye, organo-borate catalyst, and an onium salt or triazine catalyst.
12. The printing plate of claim 10 , wherein the active components include,
from about 5 to about 30 wt % based on solids content, of a urethane acrylate resin;
from about 35 to about 75 wt % based on solids content, of a radically polymerizable, multifunctional acrylate monomer and/or oligomer; and
an initiator system capable of initiating a polymerization reaction upon exposure to imaging radiation.
13. The printing plate of claim 12 , wherein the coating components include a pigment dispersion, a stabilizer, and an IR dye.
14. The printing plate of claim 1 , wherein the PS coating consists essentially of the following components, none of which are soluble or dispersible in any of the group of fluids consisting of water, fountain solution, ink and press ink:
(a) a urethane acrylate resin
(b) multi-functional acrylate monomer and/or oligomer
(c) pigment dispersion
(d) stabilizer
(e) IR dye
(f) organo-borate catalyst
(g) onium salt catalyst
(h) colorant.
15. The printing plate of claim 1 , wherein none of any of the components of the PS coating are soluble or dispersible in any of the group of fluids consisting of water, fountain solution, ink and press ink.
16. The printing plate of claim 2 , wherein the PS coating includes a monomer having a functionality of at least three and a monomer to polymer ratio in the range of about 2-4.