Patent GB-940135-A (GB)
Title: Improvements relating to photo-polymerizable compositions
IPC: C08F2/50
Filed: 1962-03-16
Abstract: 940,135. Photopolymerizable photographic plates. E. I. DU PONT DE NEMOURS & CO. March 16, 1962 [March 29, 1961], No. 10220/62. Heading G2C. [Also in Divisions B5 and C3] Photographic plates comprise a layer of a photopolymerizable composition on a support. In Example II a plate is made from granules of the composition by the method of Example 1 of Specification 883, 558. After exposure to ultraviolet radiation from a conventional ultraviolet lamp through a photographic negative and washing the exposed layer with 0. 04N sodium hydroxide at room temperature, a printing plate was obtained giving impressions of excellent quality and showing a long press life when used for printing on a rotary press. In Example VI, sheets made of the composition are calendered to a uniform thickness of 0.102 cm. and laminated on to a steel support coated with an adhesive layer as disclosed in Specification 864, 041. The laminate was cured in an oven at 145C. for 8 mins. and the resulting plate exposed and treated as above. The compositions are made by forming a mixture of (a) a cellulose partial ester of a saturated monocarboxylic acid containing 2-4 carbon atoms, (b) a dicarboxylic acid anhydride, (c) a non-gaseous addition polymerizable ethylenically unsaturated compound containing at least one terminal ethylenic (CH 2 =C=) group having a boiling point above 100C. at normal atmospheric pressure, and capable of forming a high polymer by free-radical photoinitiated, chainpropagated addition polymerization, (d) an addition polymerization initiator activatable by light of wavelength 120-700 millimicrons and having no significant thermal activity at temperatures below 50 C., and (e) a compatible, inert, liquid organic solvent of boiling point 55-180C. for said cellulose ester, in an amount sufficient to render the mixture readily stirrable, and heating the mixture while stirring to a temperature within the range 50 180C. and at which the initiator is thermally inactive until the desired degree of esterification of the cellulose ester with the dicarboxylic acid anhydride has occurred and a uniform solution has been formed. Preferably the cellulose partial ester is a cellulose acetate with a degree of substitution of about 1.85, but cellulose acetate propionate, cellulose acetate butyrate, cellulose propionate and cellulose butyrate may be used. The prefeered dicarboxylic acid anhydride is succinic anhydride, but others specified include glutaric and phthalic anhydrides. A monocarboxylic acid anhydride, preferably of an acid having 2-18 carbon atoms and especially 2-4 carbon atoms, e. g. propionic or butyric anhydride, may also be added to the mixture to introduce monoester groups into the cellulose ester. The ethylenically unsaturated compound is preferably an acrylic acid ester or methacrylic acid ester of a saturated aliphatic polyhydric alcohol or of a polyethylene or polypropylene glycol. Those specified include ethylene diacrylate, diethylene glycol diacrylate, glycerol diacrylate, glycerol triacrylate, ethylene dimethacrylate,1, 3-propane diol dimethacrylate, 1,2,4-butane triol trimethacrylate, 1,4 cyclohexanediol diacrylate, 1,4-benzenediol dimethacrylate, pentaerythritol tetramethacrylate, 1, 3-propanediol diacrylate, 1,5-pentane diol dimethacrylate, the bis-acrylates and methacrylates of polyethylene glycols of molecular weight 200-500; unsaturated amides, particularly those of the alphamethylene carboxylic acids and their alpha-alkyl substitution products, and especially those of alpha omega diamines and oxygen-interrupted alpha omega diamines, e.g. methylene bis-acrylamide, methylene bismethacrylamide, ethylene bis-methacrylamide, 1, 6-hexamethylene bis-acrylamide, diethylene triamine tris-methacrylamide, bis(gammamethacrylamido propoxy)-ethane,beta-methacryl amido ethyl methacrylate, N-(beta-hydroxy ethyl) - beta-(methacrylamido) ethyl acrylate and N, N-bis (beta-methacryloxyethyl) acrylamide; vinyl esters e.g. divinyl succinate, divinyl adipate, divinyl phthalate, divinyl terephthalate, divinyl benzene-1, 3- disulphonate and divinyl butane-1,4- disulphonate; and unsaturated aldehydes e.g. sorbaldehyde. The addition polymerization initiator may be anthraquinone or an initiator of the anthraquinone type disclosed in Specification 843.238. Preferably, the solvent is readily miscible with water. Those specified include acetone, methyl ethyl ketone, cyclohexanone and pyridine. The mixture may also contain an esterification catalyst, preferably a tertiary organic amine. Those specified include diethylcyclohexylamine, triethylamine, tributylam mine, triamylamine, tetramethylguanidine, trimethylamine acetate, pyridine acetate, sodium carbonate, sodium phosphate, sodium borate, sodium acetate, calcium acetate, magnesium acetate, potassium acetate and potassium carbonate. A thermal polymerization inhibitor may be added in an amount of 0. 001-2% by weight of the ethylenically unsaturated compound. Those specified include pmethoxyphenol, hydroquinone, p-toluquinone, alkyl- and aryl-substituted hydroquinones, t-butylcatechol, pyrogallol, naphthylamines, beta-naphthol, p-benzoquinone, 2, 6-di-t-butyl-p-cresol, dicyblopentadienyl iron, phenothiazine, pyridine, nitrobenzene, dinitrobenzene, chloranil, and thiazine dyes e.g. thionine, thionine blue G, methylene blue B and toluidine blue O. Certain salts, e. g. calcium acetate, calcium chloride, calcium nitrate, magnesium oxide, and magnesium methylate may also be added to the composition in an amount of 0. 5- 9% by weight of the composition, to prevent the formation of bloom on photopolymerizable elements made therefrom, or may be added subsequent to esterification. In a preferred method, the cellulose partial ester is slurried in the organic solvent with the desired amount of the dicarboxylic acid anhydride, the addition polymerizable ethylenically unsaturated monomer, an esterification catalyst, the addition polymerization initiator and other desired adjuvants, e. g. addition polymerization inhibitors and inert organic or inorganic filler material, and the mixture then heated in a suitable closed vessel equipped with a stireer and a reflux condenser at 50-180C.,but not higher than the boiling point of the solvent used, for 10 mins- 24 hours. Specifications 741, 294, 741, 441, 905, 070 and 905, 700 also are referred to.