DE1157077B - Process for the preparation of photographic silver halide emulsions stabilized with palladium salts - Google Patents

Description

Process for the preparation of photographic stabilized with palladium salts Halide Silver Emulsions The invention relates to the preparation of palladium salts stabilized photographic silver halide emulsions that use gelatin as a protective colloid contain.

Photographic emulsions with an addition of palladium compounds are already known, e.g. B. in German Patent 964 561. Their intended use is geared to increasing sensitivity, oversensitization and reducing fog, especially when storing photographic material at elevated temperature and humidity conditions. In the production of such halogenated silver emulsions, symptoms of desensitization and also an irregular mode of action are often observed, particularly with regard to the emulsion to be stabilized.

It was found that this irregular effect can be attributed to the formation of palladium gelatinate, which, depending on the conditions, sometimes takes place more, sometimes less, when stirring in. Is z. B. Pd (NOG) or (NH4) PdC] added aqueous 4 in the form of a 1 O / o solution of the gelatin-containing emulsion, there is obtained a local precipitation of Palladiumgelatinat, whereby the palladium remains photochemically partially ineffective.

This is the task of converting palladium in such a form into the gelatine-containing Bring photographic emulsion that the interfering interaction with gelatin is turned off. According to the invention, this is achieved by adding the emulsion Adds palladium amino acid chelate compounds.

When such compounds are added,], a precipitation phenomenon to observe. Suitable compounds are e.g. B. the chelates of palladium with Glycocolla, x-alanine, fl-alanine, serine, sarcosine, arginine, histidine, hippuric acid, Aspartic acid, glutamic acid, proline, tryptophan and others.

A similar effect is obtained when adding the ethylenediamine chelate of palladium. However, the ethylenediamine has as a chelating agent to the photeren amino acids have the disadvantage that the pII value of the emulsion is alkaline Area is moved. In addition, particularly highly sensitive emulsions show when the ethylenediamine chelate is added, there is an increased tendency to fog.

Palladium chelates can be converted into gelatin-containing ones without difficulty Stir in halogen silver emulsions. Compared to (NHI) 2PdC1, or Pd (NO1) 2 leaves The claimed compounds result in a significant improvement in the haze values in storage and the elevated temperature and humidity conditions. This effect does not change in the case of emulsions, some of which are gelatin by artificial protective colloids, such as cellulose derivatives, polyvinyl alcohol derivatives etc., is replaced.

The invention is detailed in the following exemplary embodiment described.

Example of one sensitized with sulfur and gold compounds and bromine-iodine-silver emulsion digested for optimal sensitivity, Pd-glycine chelate, Pd-glutamic acid chelate and Pd-hisfidine chelate compared to Pd (N0,), and (NHJ, PdC1 added as a pouring additive before pouring the emulsion. It was made by the individual Palladium chelate compounds added so much to the emulsion that they were compared to Pd (N0,), or (NH,), PdC1, contain the same amount of palladium. The emulsion was poured onto a film base and dried.

Samples of the dried film are exposed to X-rays between two X-ray intensifying screens behind an aluminum staircase. The exposed samples are developed in a commercially available X-ray developer for 5 minutes and 10 minutes at 20 ° C. In addition, storage of the film at 55 ° C and 700 / relative humidity for 96 hours is carried out to test the durability. These samples are exposed in the usual way and developed for 5 minutes in the X-ray developer.

The table below summarizes the results of the photographic testing of the fresh film and after storage at elevated temperature and elevated humidity. As a measure of the sensitivity, the deviation in the blackening with the same exposure at S = 1.0 was determined. veil Amount, as Pd in storage calculated, in Sensitive - 96 hours mg / kg emulsion at at 55'C and 5 minutes 10 minutes 70 1 / o more relative humidity Pd (N0,) 2 ......................... 3.9 0 0.11 0.14 0.54 Pd glycine chelate ................... 3.9 +0.08 0.12 0.15 0.38 (NH # 2PdC14 .................. .... 3.6 ± 0 0.13 0.17 0.50 Pd glycine chelate ... ................ 3.6 +0.12 0.13 0.14 0.30 Pd (N0,). ......................... 3.9 ± 0 0.13 0.15 0.72 Pd-glutamic acid chelate ............ 3.9 ± 0 0.13 0.14 0.34 (NH4), PdC14 ...................... 3.6 ± 0 0.14 0.17 0.80 Pd-glutamic acid chelate ............ 3.6 -0.12 0.13 0.17 0.38 Pd (N0,). ......................... 3.9 ± 0 0.11 0.14 0.54 Pd-ilistidine chelate .................. 3.9 +0.01 0.12 0.15 0.32 (NHO, PdC14 ...................... 3.6 : L 0 0.13 0.17 0.50 Pd-histidine chelate .................. 3.6 +0.19 0.13 0.18 0.22 From the above results it can be seen that the photographic properties of the emulsion in the fresh state are only slightly affected. The haze values of the tests after storage at 55 ° C. and 70 % relative humidity for 96 hours are considerably lower when the palladium amino acid chelates are added than in the comparison tests with Pd (NO,) 2 or (NH,), PdCl ,. This result suggests an improved shelf life of the film, especially with increased humidity.

Claims (2)

PATENT CLAIMS: 1. Process for the preparation of photographic silver halide emulsions stabilized with palladium salts, characterized in that the palladium is added to the emulsion in the form of a palladium amino acid chelate compound. 2. The method according to claim 1, characterized in that the emulsions are additionally sensitized with gold and sulfur compounds.