Process for the manufacture of silver halide photographic emulsion containing iridium and rhodium

Claim 2

IN A NEGATIVE-WORKING SILVER HALIDE PHOTOGRAPHIC EMULSION COMPRISING AN UNFOGGED SILVER HALIDE EMULSION OF SILVER HALIDE PARTICLES DISPRESED IN AN AQUEOUS EMULSION OF A HYDROPHILIC COLLOID, THE IMPROVEMENT COMPRISING A COMBINATION OF A RHODIUM COMPOUND AND AN IRIDIUM COMPOUND WHICH HAVE BEEN ADDED TO SAID EMULSION DURING THE PRECIPITATION OF THE SILVER HALIDE PARTICLES IN AN AMOUNT SUFFICIENT TO PRODUCE A HIGH CONTRAST IMAGE WITH A MINIMUM OF LATENT IMAGE SENSITIZATION.

Claim 3

The emulsion of claim 1, wherein said silver halide is silver bromide, silver chlorobromide, silver bromoiodide or silver chlorobromoiodide.

Claim 4

The emulsion of claim 1, wherein said aqueous emulsion contains ammonia.

Claim 5

The emulsion of claim 1, wherein said hydrophilic colloid is a natural organic colloid or a synthetic organic polymer.

Claim 6

The emulsion of claim 4, wherein said hydrophilic colloid is gelatin, a gelatin derivative, polyvinyl alcohol, carboxy methyl cellulose, or maleic anhydride-phthalic acid copolymer.

Claim 7

The emulsion of claim 5, wherein said hydrophilic colloid material is gelatin, phthalic gelatin, maleic gelatin, carboxy methyl gelatin, or trimellitic gelatin.

Claim 8

The emulsion of claim 1, wherein said rhodium compound is a simple salt or an octahedral complex salt of alkali metal or ammonium and wherein said iridium compound is a simple salt, an octahedral complex acid or an alkali metal or ammonium salt thereof.

Claim 9

The emulsion of claim 7, wherein said rhodium compound is rhodium dihalide, rhodium trihalide, or alkali metal or ammonium hexahalogeno rhodate and wherein said iridium compound is iridium trihalide, iridium tetrahalide, hexahalogenoiridic (III) acid, hexahalogenoiridic (IV) acid, or the salts of said acids.

Claim 10

The emulsion of claim 1, wherein both the rhodium compound and the irridium compound are water-soluble.

Claim 11

The emulsion of claim 1, wherein said iridium compound and said rhodium compound are each present at a level of 10 8 to 10 6 mol per mol of silver halide.

Claim 12

The emulsion of claim 1 wherein said combination consists essentially of said rhodium compound and said iridium compound.

Claim 13

In a process for the manufacture of a negative-working silver halide photographic emulsion having an improved property for a flash exposure comprising preparing an unfogged silver halide emulsion of silver halide particles dispersed in an aqueous emulsion of a hydrophilic colloid including two ripening steps, said emulsion being unfogged because reducing agents are not added during the second ripening step, the improvement comprising: adding a combination of a rhodium compound and an iridium compound to said emulsion during the precipitation of the silver halide particles in an amount sufficient to produce a high contrast image with a minimum of latent image sensitization.

Claim 14

In a process for the manufacture of a negative-working silver halide photographic emulsion having an improved property for a flash exposure comprising preparing an unfogged silver halide emulsion of silver halide particles dispersed in an aqueous emulsion of a hydrophilic colloid including two ripening steps, said emulsion being unfogged because reducing agents are not added during the second ripening step, the improvement comprising: adding a combination of a rhodium compound and an iridium compound to said emulsion during the precipitation of the silver halide particles in an amount sufficient to produce a high contrast image with a minimum of latent image sensitization.

Claim 15

The process of claim 12, wherein said silver halide is silver bromoiodide, silver chlorobromide, or silver chlorobromoiodide.

Claim 16

The process of claim 12, wherein said aqueous emulsion contains ammonia.

Claim 17

The process of claim 12, wherein said hydrophilic colloid is a natural organic colloid or a synthetic organic polymer.

Claim 18

The process of claim 15, wherein said hydrophilic colloid is gelatin, a gelatin derivative, polyvinyl alcohol, carboxy methyl cellulose, or maleic anhydride- phthalic acid copolymer.

Claim 19

The process of claim 16, wherein said hydrophilic colloid material is gelatin, phthalic gelatin, maleic gelatin, carboxy methyl gelatin, or trimellitic gelatin.

Claim 20

The process of claim 12, wherein said rhodium compound is a simple salt or an octahedral complex salt of alkali metal or ammonium and wherein said iridium compound is a simple salt, an octahedral complex acid or an alkali metal or ammonium salt thereof.

Claim 21

The process of claim 18, wherein said rhodium compound is rhodium dihalide, rhodium trihalide, or alkali metal or ammonium hexahalogeno rhodate and wherein said iridium compound is iridium trihalide, iridium tetrahalide, hexahalogenoiridic (III), acid, hexahalogenoiridic (IV) acid, or the salts of said acids.

Claim 22

The process of claim 12, wherein both the rhodium compound and the iridium compound are water-soluble.

Claim 23

The process of claim 12, wheRein said iridium compound and said rhodium compound are each present at a level of 10 8 to 10 6 mol per mol of silver halide.