Patent GB-410738-A (GB)
Title: Improvements in the manufacture of printing plates from plastic cellulosic compositions
IPC: B41C3/06
Filed: 1932-08-18
Abstract: Plastic cellulosic compositions particularly useful in the manufacture of cellotypes or printing-plates comprise a plurality of cellulose esters of different viscosities, but containing the same acid radicles, a small amount of plasticizer, and one or more volatile solvents, in the proportions of 12--36 per cent of total solids to 64--80 per cent of solvent or solvents.  The cellulose esters used may be nitrates or acetates.  As the plasticizers, tricresyl phosphate, triphenyl phosphate, and dibutyl phthalate are preferred for cellulose nitrate, and triacetin, tricresyl phosphate, triphenyl phosphate, dibutyl tartrate, diamyl tartrate, diethyl phthalate, and diacetin, for cellulose acetate.  Solvents specified are acetone, ethyl acetate, butyl acetate, amyl acetate, and butyl alcohol.  A mixture of ethyl acetate and alcohol, methyl ethyl ketone.  Methyl acetate, tetrachlorethane and diacetone alcohol may also be used for cellulose acetates.  Examples are given of compositions of which the solid contents comprise from 40 to 71 per cent of \ba1/2\be-second cellulose nitrate and from 20 to 43,25 per cent of 40-second cellulose nitrate.  In one example of a cellulose acetate composition, the total solids comprise 38 per cent of 5-second cellulose acetate, 57 per cent of 15-second cellulose acetate, together with 5 per cent of tricresyl phosphate, and in another example, the total solids comprise 47,5 per cent each of 1-second and 15-second cellulose acetates and 5 per cent of triacetin.  There may be present also resins or gums such as gum dammar, and also colouring matter.  In the production of printing plates, the composition is poured onto a water-swollen gelatine relief copy, covered with a backing of celluloid, and pressed into close contact with the gelatine surface.  Hardening occurs partly by precipitation by the water in the gelatine, and partly by absorption of the solvent by the celluloid backing.ALSO:Plastic cellulosic compositions comprise a phurality of cellulose esters of different viscosities but containing the same acid radicles, a small amount of plasticizer, and one or more volatile solvents, in the proportions of 12-36 per cent of total solids to 64-80 per cent of solvent or solvents.  The cellulose ester may be nitrates or acetates.  As the plasticizers, tricresyl phosphate, triphenyl phosphate, and dibutyl phthalate are preferred for cellulose nitrate, and triacetin, tricresyl phosphate, triphenyl phosphate, dibutyl tartrate, diamyl tartrate, diethyl phthalate, and diacetin, for cellulose acetate. Solvents specified are acetone, ethyl acetate, butyl acetate, amyl acetate, and butyl alcohol.  A mixture of ethyl acetate and alcohol, methyl ethyl ketone, methyl acetate, tetrachlorethane, and diacetone alcohol may also be used for cellulose acetates.  Examples are given of compositions of which the solid contents comprise from 40 to 71 per cent of 1/2 -second cellulose nitrate and from 20 to 43,25 per cent of 40-second cellulose nitrate.  In one example of a cellulose acetate composition, the total solids comprise 38 per cent of 5-second cellulose acetate, 57 per cent of 15-second cellulose acetate, together with 5 per cent of tricresyl phosphate, and in another example, the total solids comprise 47,5 per cent each of 1-second and 15-second cellulose acetates and 5 per cent of triacetin.  There may be present also resins or gums such as gum dammar, and also colouring matter.