Claims
- 1. A printing plate precursor comprising a substrate coated with a radiation sensitive composition which composition comprises at least one photoinitiator and at least one photopolymerisable compound which is an acrylic or methacrylic ester of a tetra functional polyol having the general formula:
- C(CH.sub.2 O).sub.4 (C.sub.3 H.sub.6 O).sub.n H.sub.4
- wherein the average degree of propoxylation n is from 3 to 6, from 50% to 90% of the available hydroxy groups have been converted to acrylate or methacrylate groups, and the remaining hydroxy groups have been reacted with a di-isocyanate or a polyisocyanate.
- 2. A printing plate precursor as claimed in claim 1 wherein the photoinitiator is a triazine, a ketone, a perester or an acridine.
- 3. A printing plate precursor as claimed in claim 1 wherein the composition comprises an acrylic polymer, a vinyl acetate polymer, a styrene-maleic anhydride copolymer, or a poly(vinyl acetal) as a binder resin.
- 4. A printing plate precursor as claimed in claim 1, wherein the composition includes a coumarin or bis coumarin, an .alpha., .beta.-unsaturated ketone, a methine dye or a pyrilium dye as an optical sensitiser.
- 5. A printing plate precursor as claimed in claim 1 wherein the substrate is formed of aluminium.
- 6. A method of producing a printing plate precursor which method comprises
- (i) forming a urethane acrylate or urethane methacrylate by converting from 50 to 90% of the available hydroxy group of a tetra functional polyol having the general formula:
- C(CH.sub.2 O).sub.4 (C.sub.3 H6O).sub.n H.sub.4,
- wherein the average degree of propoxylation n is from 3 to 6, into acrylate or methacrylate groups and reacting the remaining available hydroxy groups with a diisocyanate or polyisocyanate;
- (ii) admixing the urethane acrylate or urethane methacrylate with a photoinitiator to form a radiation sensitive composition, and
- (iii) forming a coating of the composition on a substrate.
- 7. A method according to claim 6 wherein the diisocyanate or polyisocyanate is additionally reacted with a compound having at least two groups which contain an active hydrogen atom.
- 8. A method according to claim 7 wherein said compound is polyethylene glycol; polypropylene glycol; 2-ethylamino ethanol; butan-1,3-diol; a polycaprolactone based diol; 3,6-dithiaoctan-1,8-diol, lactic acid or thiosalicylic acid.
- 9. A method according to claim 6, wherein the diisocyanate or polyisocyanate is 2,4 toluene diisocyanate; 2,6 toluene diisocyanate, diphenyl methane diisocyanate; hexamethylene diisocyanate; isophorone diisocyanate, or isophorone diisocyanate trimer.
- 10. A printing plate precursor as claimed in claim 1 wherein the photoinitiator is a polynuclear quinone.
- 11. A method of producing a printing plate precursor comprising the steps of:
- (i) forming a photopolymerisable compound by
- (a) providing a tetra functional polyol having a general formula:
- C(CH.sub.2 O).sub.4 (C.sub.3 H.sub.6 O).sub.n H.sub.4
- wherein n is from 3 to 6.
- (b) converting from 50% to 90% of available hydroxy groups of said tetra functional polyol to acrylate or methacrylate groups, and
- (c) reacting any unconverted hydroxy groups with a di-isocyanate or a polyisocyanate to form said photopolymerisable compound;
- (ii) admixing the photopolymerisable compound with a photoinitiator to form a radiation sensitive composition; and
- (iii) forming a coating of said radiation sensitive composition on a substrate.
Priority Claims (1)
Number |
Date |
Country |
Kind |
8622266 |
Sep 1986 |
GBX |
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Parent Case Info
This is a continuation of co-pending application Ser. No. 07/096,893 filed on 9/15/87 now abandoned.
US Referenced Citations (9)
Foreign Referenced Citations (2)
Number |
Date |
Country |
0054700 |
Dec 1980 |
EPX |
2459420 |
Dec 1974 |
DDX |
Continuations (1)
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Number |
Date |
Country |
Parent |
96893 |
Sep 1987 |
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