GB815277A - Photo sensitive addition polymerisable compositions and products made therefrom - Google Patents

Abstract

An addition photopolymerizable composition comprises more than 50 per cent by weight of (1) a solid polyester, polyacetal or mixed polyester/polyacetal of a polyvinyl alcohol having 0-15 per cent of free hydroxyl groups and 5-80 per cent of ester or acetal groups which contain non-terminal addition polymerizable ethylenic unsaturation, 5.35 per cent of (2) a compatible polymerizable monomer boiling above 100 DEG C. at atm. pressure and (3) a small amount of a free radical-generating polymerization initiator activatable by actinic light and inactive thermally below 80 DEG C. The polyvinyl alcohol from which the polyester, polyacetal or mixed polyester/polyacetal is formed may be a partially or completely hydrolysed polymer of a vinyl carboxylate or copolymer of a vinyl carboxylate with other polymerizable vinyl monomers. Suitable polyvinyl alcohols of the hydrolysed olefine/vinyl ester copolymers are described in U.S.A. Specification 2,386,347 and Specification 600,023. In addition to the unsaturated ester or acetal groups, saturated ester, acetal or ether groups may be introduced into the polyvinyl alcohol. The mixed polyesters/polyacetals may be prepared by simultaneous or separate conventional reactions. Some specified polyesters, polyacetals or mixed polyester/polyacetals are poly (vinyl alcohol co vinyl crotonate co vinyl butyral); poly (vinyl alcohol co vinyl acetate co vinyl crotonal); poly (vinyl acetate co vinyl butyral co vinyl crotonate); poly (vinyl acetate co vinyl crotonate co vinyl butyral); poly (vinyl alcohol co vinyl acetate co vinyl butyrate co vinyl butyral co vinyl crotonal); poly (vinyl alcohol co vinyl acetate co vinyl crotonate co vinyl acetal co vinyl butyral). Others include the following groups in various combinations p-sorboyloxylbenzal; o- or p-crotonoyloxybenzal; p-cinnamoyloxybenzal; m-sorbamido-benzal; cinnamal; sorbate; cinnamate; and as saturated groups benzal; benzoyloxybenzal; chloroacetal; o- or p-chlorobenzal; propionate; benzoate; sulphonic acid ester groups. Some specified monomers are acrylic or methacrylic acid; bis-acrylates or methacrylates of polyols, e.g. diethylene glycol diacrylate; glycerol triacrylate; pentaerythritol tetramethacrylate; acrylamide; methacrylamide; methylene-bis-acrylamide; the tris-methacrylamide of diethylenetetramine; vinyl benzoate; divinyl succinate; divinyl terephthalate; divinyl sulphonates; acrylamidoacetaldehyde; b -(methacrylamido) propionaldehyde; m-(a -ethylacrylamido) - benzaldehyde; p - (2 - methacryloyl - oxyethoxy) benzaldehyde; a -vinylcrotonaldehyde; a -phenylacrolein; 4-vinyl-41-formylbiphenol; 1 - vinyl - 4 - naphthaldehyde. Suitable polymerization initiators are diacetyl; benzil; benzoin; pivalin; benzoin methyl or ethyl ether; a -methyl-, a -allyl, or a -phenyl-benzoin. The compositions may include stabilizers, e.g. hydroquinone or p-tertiary-butyl catechol. The compositions are especially useful for making photopolymerizable elements consisting of a layer of the composition on a support. By exposing them to light under an image-bearing transparency and dissolving away unpolymerized composition relief printing elements can be made. They are also suitable for coatings, pellicles, sheets, cast objects or in the preparation of phosphor patterns in colour television screens. Suitable solvents for unpolymerized composition are methanol; ethanol; ethyl acetate/ethanol mixtures; acetone; methyl ethyl ketone. In the examples: I. An 86-89 per cent hydrolysed polyvinyl acetate, p-sorboyloxybenzaldehyde, glacial acetic acid, trifluoracetic and hydroquinone were heated at 60-65 DEG C., and the resultant p-sorboyloxybenzaldehyde polyvinyl acetal was precipitated with ether-petroleum ether, and purified by repeated solution in acetone and precipitation with ether. The bis-methacrylate of a polyethylene glycol (mol. wt. 200) and a little benzoin methyl ether were added to an acetone solution of the p-sorboyloxybenzaldehyde polyvinyl acetal and the solution cast on to glass at room temperature in subdued light. The film was then exposed to ultra-violet light under a line negative, and the unexposed parts removed by working with acetone to give a relief image suitable for printing. II and III were similar but used a polyvinyl acetal containing in addition to the acetoxy and hydroxy groups, either p-crotonoyloxybenzal groups, or o-crotonoyloxybenzal groups. IV. The polyvinyl alcohol was esterified with sorbic acid and acetic anhydride to form a polyvinyl acetate/sorbate free of hydroxyl groups which was used as in Example I to form a relief image in conjunction with the bis-methacrylate of polyethylene glycol. V. The poly-vinylacetal used in this example contained acetate, hydroxyl, p-sorboyloxybenzal, and p-benzoyloxybenzal groups. VI. Polyvinylacetate/cinnamate substantially free of OH groups was used as before. VII. The polyvinyl acetal used contained acetoxy, hydroxy, p-benzoyloxybenzal and p-cinnamoyloxybenzal groups. VIII. The relief printing image was prepared from a copolymer of a polyvinyl acetal containing acetate, benzal and crotonal groups with triethylene glycol dimethacrylate, again using benzoin methyl ether as catalyst. IX and X were similar to VIII but used a polyvinyl acetal containing acetoxy, butyral and crotonal groups. XI was similar to I but uses a polyvinyl acetal containing acetoxy and m-sorbamidobenzal groups. Specification 638,895 also is referred to.ALSO:p-Sorboyloxybenzaldehyde is prepared by reacting sorboyl chloride with p-hydroxybenzaldehyde in methylene chloride in the presence of triethylamine, at 15-20 DEG C. o- and p-Crotonoyloxybenzaldehydes and p-cinnamoyloxybenzaldehyde are similarly prepared. In Example XI m-sorbamidobenzaldehyde ethylene glycol acetal is prepared by reacting m-aminobenzaldehyde ethylene glycol acetal (see Specification 638,895) in acetone with a dioxane solution of sorboyl chloride at 0-5 DEG C. and pH 7-9.