GB986949A - Improvements relating to photopolymerizable compositions and their production - Google Patents

Abstract

Photopolymerizable compositions comprise, by weight (a) 10-60 parts of an addition polymerizable, non-gaseous, ethylenically unsaturated compound containing at least one terminal ethylenic group, having a boiling point above 100 DEG C. at normal atmospheric pressure and capable of forming a high polymer by free-radical initiated addition polymerization; (b) 40-90 parts of cellulose acetate hydrogen succinate having a degree of acetyl substitution of 1.5 to 2.45 and of hydrogen succinate substitution of 0.4 to 1.0, as bending agent; (c) 0.1 to 10.0 parts of maleic, glutaric, glycollic, lactic or citric acid, or a mixture of two or more such acids. The polymerizable compound (a) may be e.g. a polyethylene glycol diacrylate prepared from a diol precursor of molecular weight 300-600. The composition may also contain a free-radical generating, light activated initiator, e.g. 2-ethylanthraquinone and those disclosed in Specification 843,238, and also a polymerization inhibitor, e.g. p-methoxyphenol, hydroquinone, aryl- and alkyl-substituted hydroquinones, t-butyl catechol, pyrogallol, copper resinate, naphthylamines, b -naphthol, cuprous chloride, 2,6 - di - t - butyl - p - cresol, phenotriazine, pyridine, nitrobenzene, dinitrobenzene, p-toluquinone, and chloranil. The compositions may be made by merely mixing the constituents. Alternatively, the cellulose ester may be formed in situ by a melt esterification using a catalyst such as diethyl cyclohexylamine, pyridine, triethylamine, tributylamine, triamylamine, trimethylamine acetate, pyridine acetate, sodium or potassium carbonate, sodium phosphate, acetate, and borate, or lithium, calcium, potassium or magnesium acetates. The catalyst may comprise up to 20% of the composition. In an example, a mixture of pulverized cellulose acetate (D.S. 1.85), polyethylene glycol diacrylate, succinic anhydride, p-methoxyphenol and 2-ethylanthraquinone is milled at 135 DEG C. After addition of diethyl cyclohexylamine catalyst and further milling to form cellulose acetate succinate, glutaric acid is added to complete the photopolymerizable composition. The compositions are formed into sheets by calendering which are then laminated on to supports, with or without an adhesive, to form photopolymer printing plates (see Divisions B5 and G2). Specifications 741,294, 741,441, 741,470, 807,948, 825,795, 834,337, 850,453, 854,980, 864,041, 883,558, 905,070, 935,627 and 945,807 also are referred to.