GB877841A - Improvements relating to radiation-sensitive silver halide emulsions - Google Patents

Abstract

877,841. Photographic emulsions. DU PONT DE NEMOURS & CO., E. I. Nov. 27, 1959 [May 22, 1959; Nov. 12, 1959], No. 40465/59. Class 98(2) A light-developable light-sensitive waterpermeable colloid-silver halide emulsion contains at least 0.5 % mole of a stannous salt and at least 0.1 % mole of a plumbous salt per mole of silver together with an excess of bromine ions over the amount equivalent to the silver. Preferably the emulsion contains 0.5 to 12.0% mole of stannous salt such as stannous chloride, 0.1 to 25% mole of plumbous salt such as plumbous nitrate, at least 50% excess of bromine ions present as magnesium, calcium, ammonium, or potassium bromide and the colloid is gelatin. Other colloids which may be used are watersoluble or water-permeable vinyl polymers such as polyvinyl alcohol; partially hydrolyzed polyvinyl acelates, ethers and acetals; hydrolysed interpolymers of vinyl acetate and maleic anhydride ethyl acrylate and methacrylate, olefines, or styrene; polyvinyl lactams as in U.S.A. Specification 2,495,918; polyvinyl pyrollidone; hydrophilic acrylic and methacrylic acid amine copolymers as in Specificacation 788,343; and hydrophilic cellulose ethers and esters. The emulsions are made by adding the stannous and plumbous salts as solutions in water, sorbitol or glycerine in either order to a silver halide emulsion without or after washing sensitizing dyes may be added also. The emulsion may be coated on any suitable support, glycerine solutions of the metals salts being used if the support is to be of paper for which glycerine is an anti-curl agent. Specifications 542,704 and 600,023 also are referred to.