US 3846133 A
Description (OCR text may contain errors)
United States Patent MULTILAYEREI) COLOR PHOTOGRAPHIC MATE- RIAL WITH IMPROVED STABILITY UNDER TROPICAL CONDITIONS Hugo Zorn, Munich-Lochhausen, Helmut Broil, Munich, and Erich Reckziegel, Leverkusen, Germany, assignors to Agfa-Gevaert Aktiengesellschatt, Leverkusen, German No i Drawiug. Filed Oct. 4, 1972, Ser. No. 294,955 Claims priority, application Germany, Oct. 6, 1971, P 21 49 837.3 Int. Cl. G03c 1/76, 3/00 US. Cl. 96--'74 3 Claims ABSTRACT OF THE DISCLOSURE Stability to tropical conditions of color photographic multilayer materials comprising blue, green and red sensitive silver halide emulsion layers and color couplers therein, is improved if the red sensitized and/ or the green sensitized silver halide emulsion layer contains colloidal silver.
This invention relates to a multilayered color photographic material whose stability under tropical conditions is improved by the addition of colloidal silver to at least one spectrally sensitized silver halide emulsion layer.
In order to enable photographic films to be stored under mild climatic conditions or at elevated temperatures, the necessary stability can be achieved by after-ripening the silver halide emulsions and by adding stabilizers such as mercapto compounds, organic disulfides, alkali metal thiosulfate complexes or triazaindolizines to the emulsions before casting the emulsions on a layer support. In many cases, particularly in color photographic films, these measures are not sufficient to ensure that the material will be stable when stored under tropical conditions with high humidities.
It has now been found that the stability of multilayered color photographic material against tropical conditions can be improved if at least one of the two silver halide emulsion layers which contain color-forming couplers and are sensitized to the red or green region of the spectrum respectively contains colloidal silver.
It is thought that this stabilizing efiect is due to the colloidal silver protecting the sensitivity centres against the action of temperature and atmospheric moisture. In principle, any form of colloidal silver would have the effect required according to the invention but the yellow form dispersed in gelatin, so-called yellow silver, is pre ferred because it is almost completely transparent to red and green light and absorbs only blue light which is unwanted in the cyan-forming and magenta-forming layers. The blue sensitive yellow-forming layer, whose sensitivity would be reduced to a greater extent by the yellow silver, is in most cases much more resistant to tropical conditions than the cyan-forming and the magenta-forming layer and therefore generally, does not need stabilization with yellow silver. The quantities of colloidal silver to be added depend on the degree to which the stability under tropical conditions is required to be increased. In practice, it has been found that quantities of between 0.02 and 0.8 g. of colloidal silver per mol of silver halide are necessary in the emulsion to achieve the stabilizing effect. These quantities have little or no effect on the maximum reversal color density. The preparation of various types of colloidal silver has been described in the literature, e.g. in Weisers Colloidal Elements, Wiley & Sons, New York, 1933, which describes the preparation of yellow colloidal silver by the dextrin reduction method of Carey Lea, in German Pat. No. 1,096,193 (colloidal brown and black silver) and in US Pat. No. 2,688,601 (colloidal blue silver).
3,846,133 Patented Nov. 5, 1974 The invention is explained with the aid of the following examples which demonstrate the colloidal silver of various forms is suitable for improving the stability under tropical conditions regardless of the nature of the emulsion, of the color coupler and of the method of color development, whether it be reversal development or negative development.
EXAMPLE 1 Starting with a highly sensitive silver iodobromide emulsion which has been sensitized to the red region of the spectrum and which contains 5 mols percent of AgI, and 100 g. of 1-hydroxy-N-octadecyl-Z-naphthamide per mol of silver halide as cyan-forming coupler three samples containing 0, 0.4 or 0.16 g. respectively of colloidal yellow silver per mol of silver halide were cast on a layer support of cellulose acetate. The silver content of the layer was 2 -g./m. From each sample, an unexposed strip *was stored for 7 days under conditions simulating a tropical climate, the temperature being 35 C. and the relative atmospheric humidity These strips and a corresponding strip of each sample which had not been stored in a tropical cupboard were exposed through a grey sensitometer wedge. The sample were developed by a process of color reversal development as follows:
(1) First development: 12 minutes at 24 C. in a thiocyanate-containing metol-hydroquinone developer of the following composition:
Sodium ethylene diaminotetraacetate g 2 p-N-monomethylaminophenol semisulfate g 4 Sodium sulfite g 50 Hydroquinone g 6 Sodium carbonate g 35 Sodium thiocyanate :g 1.5 Potassium bromide g 2 Potassium iodide g 10 Benzotriazole mg 250 Made up with water to 1000 ml.
(2) Washing: 5 minutes.
- (3) Second exposure: 1 minute.
(4) Reversal development: 15 minutes at 24 C. in a color developer of the following composition:
Nitrilotriacetic acid g 2 Sodium sulfite g 5 Hydroxylarnine sulfate g 1 Trisodium phosphate g 20 Potassium bromide g 1 Potassium iodide mg 10 4 amino 3 methyl N ethyl N (ti-methylsulfonamidoethyl -anilinosesquisulfate monohydrate g 9 50% ethylene diamine ml 6 Made up with water to 1000 ml. pH 12.0.
The samples were then treated by the usual methods of clarifying, bleaching the silver, fixing and washing. The developed strips were assessed in a Macbeth densitometer behind a red filter.
The following table shows the specific sensitivity Ss=log I -t for the color density CF (C =color fog at total exposure) and the maximum color density D,,,,,, as well as the changes in these values AS and AD observed after storage under tropical conditions.
TABLE 1 G. of colloidal silver per mol of silver halide--." 0. 04 0. 16
S. 2. 54 2. 57 2. 54 AS. (alter storage under tropical conditions)- 0. 30 -0. 23 0. 19 m 2.36 2.36 2.40 ADmBX. (after storage under tropical conditions) 0. 20 +0. 07 +0. 06
behind a green filter.
TABLE 2 G. of colloidal silver per mol of silver halide 0 0. 04 0. l6 0. 64
2. 34 2. 33 2. 47 --0. 21 0. l7 --0. l1 2. 90 2. 94 2. 6G -0. 0. 02 0. 01.
This table again clearly shows the stabilizing elfect of colloidal yellow silver. It reduces the maximum color density D of the fresh material to a slight extent but has no deleterious eilect on the specific sensitivity S EXAMPLE 3 The procedure is the same as that employed in Example 2 except that g. of a white coupler of the formula 1 (4 sulfophenyl)-3-heptadecyl-4-methyl-pyrazolone- (5) are added per kg. of emulsion in addition to 48 g. of the magenta-forming coupler previously mentioned.
TABLE 3 G. of colloidal silver per mol of silver halide 0 0. 20 0. 40
S, 2. 84 2. 72 2. 66 AS! (after tropical storage 0. 54 0. 48 -O. 13 m" 2. 94 2. 92 2. 94 ADM; (after tropical storage) 0. 16 0. 22 0. 20
EXAMPLE 4 The procedure is the same as that employed in Example 1 except that a silver iodobromide emulsion of medium sensitivity containing 4 mol percent of AgI is used instead of the highly sensitive emulsion.
TABLE 4 G. of colloidal silver per mol of silver halide EXAMPLE 5 The procedure is the same as that employed in Example 4 with the exception that various types of colloidal silver "re added to the medium sensitivity cyan-forming layer to improve the stability under tropical conditions. The materials are subjected once to a reversal development as in the previous examples and once to a conventional color negative development using a color developer of the following composition:
Benzyl alcohol ml 4.2 Sodium hexametaphosphate g 2 Sodium sulfite anhydrous g 2 Potassium bromide g 1.5 Sodium metaborate cryst g 4 amino 3 methyl N ethyl N (B methylsulfonamido ethyl) anilinosesquisulfate monohydrate g 5 Made up with water to 1000 ml. pH l0.8i0.l.
Development temperature, 24 C. Development time, 12 minutes.
The relative sensitivity S achieved in colour negative development is indicated in log I 1 units measured at density 0.1 over the fog.
TABLE 5 Colloidal yellow Grey Nature of colloidal silver added silver 1 brown 2 Black 3 G. of colloidal silver per mol of silver halide 0. 60 0. 60 0. 60 Reversal development:
2. l9 2. 23 2. 10 A S! (after troplcal stcrag +0. 01 -0. 16 0. 20 ms; 2. 1. 84 2. 14 2. l2 ADmsx. (after tropical storage), +0. 11 -0. 14 +0. 01 0 Colour negative development:
S 3. 40 3. 30 3. 25 3. 15 A S (after tropical storage)-. 0. 42 +0. 12 -0. 27 0 1 Prepared by Carey Leo. method.
According to D.B.P. No. 1,096,193, Example 1, but without blue black particles. tiglggcording to D.B.P. No. 1,096,193, Example 1 (with blue black par- What is claimed is:
1. A color-photographic multilayer material having compounds that produce a negative image by imagewise exposure followed by developing treatment or reversal treatment producing positive image comprising at least one red-sensitized silver halide emulsion layer containing a cyan-forming coupler, at least one green-sensitized silver halide emulsion layer containing a magenta-forming coupler and at least one blue-sensitive silver halide emulsion layer containing a yellow-forming coupler, wherein the improvement comprises at least one of the emulsion layers of the group consisting of green-sensitized and redsensitized emulsion layers comprises in the same phase a binder, a silver iodobromide colloidal silver and the color coupler.
2. A color-photographic material as claimed in claim 1 wherein said colloidal silver containing layer contains 0.02 to 0.8 :g. of colloidal silver per mol of silver iodobromdie.
3. A color-photographic material as claimed in claim 1 wherein the said colloidal silver containing layer contains a gelatin binder and a yellow colloidal silver.
References Cited UNITED STATES PATENTS 2,673,800 3/1954 Meeussen et al. 9674 X 2,704,711 3/1955 Hanson, Jr. 9674 X 2,875,052 2/1959 Weyde 9668 3,206,310 9/1965 Herz 9667 3,211,552 10/1965 Chu 9674 DAVID KLEIN, Primary Examiner A. T. SURO PICG, Assistant Examiner U.S. Cl. X.R. 96-22, 114.7