Radiation imagery chemistry: process – composition – or product th – Imaged product – Including resin or synthetic polymer
Patent
1996-03-21
1999-11-02
Hamilton, Cynthia
Radiation imagery chemistry: process, composition, or product th
Imaged product
Including resin or synthetic polymer
4302811, 430302, 4302831, 4302851, 4302871, 430911, 430906, 430947, 430919, 430915, 430926, 430923, 430945, 522 18, 522 28, 522 27, 522 26, G03F 7029
Patent
active
059767359
DESCRIPTION:
BRIEF SUMMARY
OBJECT OF THE INVENTION
The use of photoinitiators to enhance the U.V. sensitivity of photopolymerisable compositions is well known and includes such compounds or mixtures as trihalomethyl substituted-S-triazines, 9-phenyl acridine, thioxanthones together with dialkylamino compounds, basic acridine compounds and halo-methyl triazines and bis acyl phosphine oxide compounds.
However recently materials which are photosensitive in the visible light regions as well as in the U-V regions are beginning to displace silver sensitised compositions. In particular photopolymerisable compositions which can be laser imaged are required. These compositions must have a high sensitivity and can be photosensitive up to about 550 nm.
Metallocene compounds have been described as photoinitiators for photopolymerisable mixture for example in U.S. Pat. No. 3,717,558. Other metallocenes and in particular titanocenes are described for this same use in E.P.A. 119162, 122223 and 186626. However such metallocenes are not particularly soluble in the solvent usually used to coat photopolymerisable compositions and furthermore are not particularly sensitive to visible light for example an argon ion laser.
We have found a lithographic plate which comprises a photopolymerisable composition which comprises a metallocene which is soluble in the solvents used to coat photopolymerisable compositions and which is sensitive to visible light.
SUMMARY OF THE INVENTION
According to the present invention there is provided a lithographic plate which comprises a base coated with a photopolymerisable composition which comprises a polymeric binder, at least one free-radically polymerisable ethylenically unsaturated compound and as the photoinitiator combination a metallocene compound N-phenyl glycine or a substituted N-phenyl glycine or an N-phenyl glycine derivative together with a third component which is a substance which helps in the reaction initiation but also increases the sensitivity of the photopolyinerisable composition to a desired region of the spectrum, and which is selected from compounds which comprise an acridine, phenazine or quinoxaline moiety, from dibenzalacetone or coumarines or which is a dye selected from xanthene, benzoxanthene, benzothioxanthene, thiazine, pyronine, porphyrin or acridine dyes.
The metallocene when light exposed generates free radicals which cause the polymerisable ethylenically unsaturated compound to polymerise. This reaction is speeded-up by the presence of the N-phenyl glycine compound. The presence of the third component also aids to increase the speed of polymerisation. The choice of this compound depends on the wavelength of the exposing source to be used.
If the composition is to be exposed to the near ultra-violet region of the spectrum then the third component of the composition useful compound are those which comprise an acridine, phenazine or quinoxaline moiety. Examples are acridine substituted in the 9 position, such as 9-phenyl-, 9-p-methoxyphenyl- or 9-acetylaminoacridine, or acridine derivatives having fused-on aromatic rings, for example benz[a]acridine. A suitable phenazine derivative is, for example, 9,10-dimethylbenz[a]phenazine. Suitable quinoxaline derivatives are in particular 2,3-diphenyl derivatives which are preferably further substituted in the two phenyl preferred. The amount of this component in the mixture is in the range from about 0 to about 10% by weight, preferably between about 0.05 and 5% by weight.
For sensitisation to the visible region compounds of the dibenzalacetone or coumarin type are particularly useful. Suitable representatives of these compounds are 4,4'-disubstituted dibenzalacetones, for example diethylamino-4'-methoxydibenzalacetone, or coumarin derivatives, such as 3-acetyl-7-diethylamino-, 3-benzimidazolyl-7-diethylamino- or carbonyl-bis(7-diethylaminocoumarin). The amount of these compounds in the mixture are in the range from 0 to about 10, preferably about 0.05 to 4% by weight.
Alternatively, many dye types are particularly useful for spectral sensitisat
REFERENCES:
patent: 5011755 (1991-04-01), Rohde et al.
patent: 5229253 (1993-07-01), Zertani et al.
patent: 5397675 (1995-03-01), Arimatsu et al.
Yamashita et al, 118: 136273 from Chemical Abstracts, ACS, English Abstract of JP04-184344 published Jul. 1, 1992.
Toyo Kogyo Co, 92-272226 Frow WPIDS F..sup.1 e, Derwent Information LTD, English Abstract of JP04-184344 published Jul. 7, 1992.
Bennett Peter Andrew Reath
Horne Geoffrey
McCullogh Christopher David
Monk Alan Stanley Victor
Hamilton Cynthia
Kodak Polychrome Graphics LLC
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