| 摘要 |
A polymeric ester comprises an acrylic acid or an alpha-alkacrylic acid polymer substantially completely esterified with amino-alcohol salt residues of which 35 to 75 per cent contain tertiary amino salt groups and 65 to 25 per cent contain quaternary amino salt groups, the anions of the salt residues being of the nonphotographically active type. Suitable anions are those of sulphuric, methanesulphonic, ethanesulphonic, decanesulphonic, dodecanesulphonic, benzenesulphonic, p-toluenesulphonic, cyclohexanesulphonic, methylsulphuric, phosphoric and perchloric acids. The copolymers may be obtained by copolymerizing in an aqueous solution having a pH between 6.5 and 7.5 a mixture of an ester containing a tert.-amino alcohol salt group, e.g. diethylaminoethyl methacrylate methylsulphate, and an ester containing a quaternary amino salt group, e.g. methyldiethylmethacryloxyethylammonium methylsulphate, in the presence of a catalyst such as ammonium persulphate, benzoyl peroxide, hydrogen peroxide and azo-bis-isobutyramidine hydrochloride. Too high a rate of polymerization may be reduced by the addition of an inhibitor, e.g. tert.-butyl catechol or oxygen. The copolymers are used in the preparation of photographic emulsions. Other unsaturated monomeric esters of amino alcohols from which suitable tertiary and quaternary esters may be prepared are described in U.S.A. Specification 2,138,763. Specifications 600,023 and 718,422 also are referred to.
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