GB1128959A - Improvements in or relating to photographic emulsions - Google Patents

Abstract

1,128,959. Making photographic silver halide emulsions. MINNESOTA MINING & MFG. CO. Jan.31, 1966 [Feb.26, 1965], No.4210/66. Heading G2C. A silver halide emulsion which may contain a synthetic binder in place of part or all of the gelatine is made by mixing a water-soluble silver salt, e.g. silver nitrate, with a water-dispersible polymeric polyamine halide or quaternary halide in an aqueous medium to precipitate silver halide. The binder may be present or may be added at a later stage, e. g. after ripening, and part or all of the polymeric polyamine may be subsequently removed. The polymeric polyamine halide may be the halide formed by reacting the polyamine with a hydrohalic acid or the quaternary halide formed by quaternising the polyamine with an alkyl or aryl halide. Polyamine halides mentioned are the hydrobromides of polyethylenimine, poly(N-hydroxyethyl ethylenimine) and polypropylenimine and poly-4-vinylpyridine quaternised with ethyl α-bromoacetate. Other polyamines specified are polyaminoalkyl acrylates, copolymers of polyethylenimine and polypropylenimine and of polyethylenimine and polyethylene oxide, and mixtures of polymers. Synthetic binders mentioned are polyvinyl alcohol which may be cross-linked by form-aldehyde, mucochloric acid or tris-(1-aziridinyl) phosphine oxide, hydroxyethyl cellulose, hydroxypropyl cellulose and polyvinyl-pyrrolidone. A comparative Example is given in which a poly-ethylenimine and polyvinyl alcohol solution, acidified with nitric acid and to which potassium bromide has been added, is mixed with silver nitrate solution and coated on a support.