| PATENT ASSIGNEE'S COUNTRY | Belgium |
| UPDATE | 01.00 |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT CLAIMS |
Method for prepg a gelatinous emulsion having grains rich in AgCl, wherein > 70%, of total projected area of all grains is provided by {111} tabular grains having an av aspect ratio > 2:1, an av. equiv. circular diam. > 0.3 micro.m & an av. thickness 0.05-0.25 micro.m wherein a % variation on av equiv circular diam. is < 30% & wherein % variation on av thickness < 20% & wherein said tabular grains are present in % numerical amounts > 90%, said method comprising - Prepg in a reaction vessel a dispersion medium compri sing an initial amount of a crystal habit modifying agent - Precipitating therein AgX crystal nuclei by double-jet preci pitation of an aq AgNO3 & an aq soln comprising halide ions, wherein < 10% by wt of total amount of AgNO3 used is consumed - Growing said AgX crystal nuclei by further precipitation of AgX by means of double-jet precipitation of an aq AgNO3 soln & an aq soln comprising halide ions, wherein > 90% by wt of a total amount of AgNO3 is consumed, characteri zed in that during at least one of the said steps at least one compd is added to the said reaction vessel, said compd being a hydrophilic amphoteric block copolymer contg (i) Non-ionic acrylic block comprising a seq. of units having (Meth)acrylonitrile derived units (I) & (ii) A acrylamid(in)ic block comprising (meth)acrylamide derived units (II) |
| PATENT PHOTOCOPY | Available on request |
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