US1758576A - Light-sensitive silver-halide emulsions and process of manufacturing the same - Google Patents

Description

Patenteday, 7

OTTO MATTHIES AND BRUNO WENIDT, OF DESSAU IN ANHALT, GERMANY, ASSIGNORS no .AGF'A AN$CO conronerron, or BINGEAMTON,.NEW YORK, A cosronnrron NE'WYORK r v LIGHT-SENSITIVE SILVEKHALIDE Eo'DrawingQ Application filed January 28,1929, Serial No. 335,732, andin Germany January 31, 1928.

The present invention relates to photographic silver salt emulsions of increased stabilityylittle tendency to fog and determined grain size, to layers containing the same and to a process for manufacturing the same.

I In our copending up lication Ser. No. 335,733,",filed this same ay we havestated that compoundswith three or more nitrogen compounds iii-"the molecule one ofwvhich is linked to hydrogen being liable to substitution by silver and forming of no highersolubility :t on silver chloride are good stabilizers for photographic cmula sions.

lVe found that also sulphur compounds forming stable'silver salts with the group --SAg, these sil-ver salts having the solubility characteristics cited above, can be em- I ployed for the same purpose incmulsion manufacture. They may be added to the finished I emulsionor to its constituents at any stage 7 of their manufacture or of emulsion-making. The compounds which form silver salts of the least solubilityexert the strongest effect on 95 the stability of emulsions.

W'e further found that the said compounds when present during the addition ofthe silver nitrate solutionrestrain the growing of silver bromide grains and thus give to the emulsion asteeper gradation while atj'the same time increasing its stability.

' By our present'process we may thus obtain emulsions of varying steepness jof gradation though starting with the same proportions of constituents. I

I The following examples illustrate the in vention: J

' Example L-A highly sensitive negative emulsion is made according to any known prescription and before the silver solution is run into the potassium bromide solution there are added to the latter 100 milligrams of thioglycollic acid per each 100 grams of silvernitrate. There is thus obtained a very finely grained, hard emulsion, whichis particularly suitable for copying black and white work.

Ewampi'e f2.--The procedure is the same as that described in Example 1, using as the added substance milligrams of thiolactic acid. There is obtained an emulsion which nmonsrons AND Tan erine stable silver salts ent of the emulsion BEGCESS 0F WUFAGTURING Example 3.-+;'io a negative emulsion made with a gelatine'which produces fog according to any known prescription, there are added per kilo of emulsion, before the pouring operation? milligrams of QB-dimercapto-d-keto-i-lo-diphenylpenthiophen. There is obtained an improvement in durability amountlngto 50 per cent.

Emample 4 .There are added to a positive bility, in Which'there is added to the emulsion a, sulphur compound forming a stable silver salt with the group SAg and having no higher solubility than silver chloride.

' 2. A process of manufacturing light sensitive silver halide emulsions of increased stability, in which there is added to a constituent of the emulsion at any stage of the manufacture a sulphur compound forming a stable silver salt with the group SAg and having no higher solubility than silver chloride;

3. A process of manufacturing light sensi tive silver halide emulsions of increased stability and restrained size of silver halide grains, in which there is added to a constitu- IlOI t'O the addition of silver nitrate a sulp iur compound forming a stable silver salt with the group --S Ag and having no higher solubilitylhen silver chloride.

4. A process of manufacturing light sensitive silver halide emulsions comprising the step of adding allyla'rninothiobiuzolesulfhy-' d1-ate.

5. A process ofmanufacturinglight sensitive silver halide emulsions comprising the step of adding alllylaniinothiobiazolesulfhydrate to a constituent of the emulsion at any stage of its manufacture.

6. Light sensitive silver halide emulsions containing a sulphur compound forming a i is suitable as a cinema film positive-e1nulsion.

stable sil ver salt with the group --SAg and heaving no higher solubility than silver chlom e.

7..Li ht sensitive silver halide emulsions cuntainmg a11ylavminqthiobiazolegulfhydrate; Q In testimony WIZQRQQQ l' fgfi x- Q1111 signa-V tures. V

OTTO MATTHIES.

BRUNO WEND T'. Y