| PATENT ASSIGNEE'S COUNTRY | Belgium |
| UPDATE | 07.00 |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT CLAIMS |
Method for prepg an emulsion having grains rich in AgBr in the presence of gelatin as a protective colloid in a reaction vessel wherein a yield of > 250 g, expressed as amount of AgNO3, equiv. with the amount of precipitated AgX/L of reaction vessel mixt is attained, wherein > 70% of a total projected area of all grains is provided by {111} tabular grains having an av aspect ratio > 2:1 & av thickness 0.05-0.3 micro.m & wherein ratio by number of hexagonal tabular grains to triangular tabular crystals present > 10:1; said method comprising following steps - Prepg in reaction vessel a gelatinous dispersion medium contg an initial amount of gelatin corresponding with < 50% of a total amount of gelatin used in the said method, said initial amount of gelatin having an av methionine content < 30 micro.moles/mole & said dispersion medium having a vol. < 2 liter per 500 g, expressed as amount of AgNO3, equiv. with the amount of precipitated AgX - 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 - Adding to said reaction vessel gelatin in an amount of > 50 % of total amount of gelatin used in said method; - 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 - Concentrating by ultrafiltration the said reaction mixt vol. in the said reaction vessel obtained during precipitation growth steps |
| PATENT PHOTOCOPY | Available on request |
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