CS243387B1 - A method for preparing chloro-bromosilicate photographic dispersions for low silver colored positive materials - Google Patents

Abstract

The invention relates to a method for preparing chloro-bromosilver photographic dispersions for color positive materials with a low silver content, characterized in that the dispersion is precipitated by the simultaneous inflow of silver nitrate and halide salts into a precursor containing an aqueous colloidal medium, without measuring the pAg value in the reaction mixture and subsequent regulation of the amount of added salts, where the desired morphology and dispersion parameters are achieved by the presence of Cd, Pb, Zn, Ti or Bl salts in the reaction mixture.

Description

(54) Method for preparing chloro-bromide silver photographic dispersions for color positive materials with low silver content

The invention relates to a method for preparing chloro-bromosilver photographic dispersions for color positive materials with a low silver content, characterized in that the dispersion is precipitated by the simultaneous inflow of silver nitrate and halide salts into a precursor containing an aqueous colloidal medium, without measuring the pAg value in the reaction mixture and subsequent regulation of the amount of added salts, where the desired morphology and dispersion parameters are achieved by the presence of Cd, Pb, Zn, Ti or Bl salts in the reaction mixture.

243387 2

The present invention relates to a method for preparing chloro-bromide silver photographic dispersions for color positive materials with low silver content.

The common method used in the preparation of chloro-bromide silver dispersions for color positive materials is the classic single-jet precipitation, in which a silver nitrate solution is added to a master batch containing a solution of halides and a protective colloid.

This usually results in a silver halide whose microcrystals do not have crystallographically definable surfaces and the resulting dispersion is characterized by a broad distribution curve of microcrystal sizes.

The second method used is the newer two-jet precipitation, in which solutions of silver nitrate and halo salts are simultaneously introduced into a sample containing a protective colloid.

The solution of the incoming components, usually halides, is regulated depending on the desired concentration of Ag ⁺ ions (pAg value) in the sample.

This method usually produces microcrystals of silver halides with crystallographically definable surfaces (mostly cubic, octahedral or dodecahedral structures) and a very narrow distribution curve of microcrystal sizes.

The disadvantage of single-jet precipitation of photographic dispersions, which is described in a number of publications, such as C. S. K. Hees and T. H. James Theory of the Photographie Process, 3rd edition Haemillan New York (1966), P. Olafkides, Chimie Photographigue, P. Montel, Paris (1957) and H. Frlaser Die Orundlagen der photographisehen Procease mit Silberhalogenlden, Akademische, Verlagsgesellsehaft (1968), is the low loss of the resulting dispersions, which then has to be compensated for by the high silver content in the resulting color positive material.

In the case of two-jet precipitation, which is described in a number of publications, such as Fundamental Aspects of Growth and Shape of Photogr. Silver Hallde Crystal published in the proceedings of the 5th International Conference of 18 July 1965 in Bern, H. Klein, Moisar Propertiea of Photographie Smulaions Oraine J. Phot. Sei. 12 242-251 (1964) and in a number of patent documents, such as VS 3 999 048 and DS 2 534 965, the narrow distribution curve of the particle size distribution of the photographic dispersion means a high steepness and, consequently, a lower silver content per area in the resulting photographic material.

However, compared to single-jet precipitation, double-jet precipitation is very demanding in terms of precise regulation of the inflow of individual photographically effective components, the intensity of mixing, the type of stirrer, the design of the reaction vessel, the reproducibility of measurements and the regulation of the pAg value.

For this reason, the two-jet precipitation of photographic dispersions is very expensive in terms of investment, both in terms of machinery and the relevant control electronics and measuring technology.

The above disadvantages of the existing methods are eliminated by a new method of preparing photographic dispersions according to the invention. The subject of the invention is a method of preparing chloro-bromosilver photographic dispersions for color positive materials with a low silver content per unit area of the poured photographic material, which is characterized in that the dispersion is precipitated by the simultaneous inflow of a silver nitrate solution and a solution of halo ions into a template containing an aqueous colloid medium, without measuring the pAg value of the reaction mixture and subsequent regulation of the amount of supplied solutions, while the desired morphology* and dispersion parameters are achieved by the presence of Cd, Pb, Zn, Ti or Bi ions in the reaction mixture.

The bromide content in the dispersion is in the range of 3 to 30%, and preferably 8 to 6%. The amount of Cd, Pb, Zn, Ti or Bl salts in the precipitation of the dispersions is in the range of 0.001 to 0.1%, and preferably 0.01 to 0.05 mol/mol Ag.

Cadmium chloride, bromide or iodide are used as Cd salts, lead nitrate as Pb salts, zinc chloride as Zn salts, thallium nitrate as TI salts and bismuth nitrate as Bi salts. Removal of water-soluble inorganic salts formed during dispersion formation can be achieved by classical washing of the gelatin gel dispersion with cold water or decantation with water after separation of the solid phase of silver halide using a flocculant.

Anionic polymers, e.g. polystyrene sulfonic acids, sulfonated styrene polymers and copolymers, as disclosed in patent document DB 1,085,422, anionic surfactants, sulfonated naphthols, their derivatives, inorganic salts, organic solvents, such as acetone, ethanol and others, as disclosed in patent documents US 2,618,556, 2,565,418, 3,241,969, can be used as flocculants.

Gelatin derivatives can also be used as flocculants, e.g. phthalyl gelatin, as described in US Patent Nos. 2,614,928, 2,614,929, 2,728,662 and others, and preferably a phenylcarbayl derivative of gelatin.

For redispersion of dispersions, gelatin, gelatin derivatives, hydrolyzed gelatin can be used, as described in US Patent No. 3,778,278, polymeric substances of natural origin such as albumin, agar, gum arabic, casein, dextran, hydrophilic cellulose polymers, cellulose esters, as described in a number of patent documents, e.g. in US Patent No. 2,327,808, synthetic polymers such as acrylamide polymers, copolymers, polyvinyl alcohols and their derivatives, polyvinyl acetals, alkylated and sulfoalkylated acrylates and methacrylates, polyvinylpyrrolidones, polyvinylpyridines, maleic acid copolymers, vinylamine copolymers, polyalkylene imines and their copolymers, vinylimide gels and others, as described, e.g. in US Patent Nos. 2,253,078 and 2,484,456.

The photographic dispersions according to the invention can be chemically sensitized with conventional chemical sensitizers containing sulfur, selenium, or tellurium, such as active gelatin, thiosulfate, thiosulfate, thio- and dithiocarbamides, thioacetals, allyl isothiocyanate, S-allyl-thiourea and allylseleno-(telluro)-thiosulfate, reducing agents such as stannous chloride, aminomethanesulfinic acids, polyamines, thiosulfate dioxide, hydrazides, and other agents as disclosed in a number of patents, e.g. in U.S. 1,623,499,

399,083, 3,297,447, 3,501,313, 3,518,689.

They can be sensitized with platinum group metals, such as gold, rhodium, iridium, platinum, palladium, ruthenium in the form of organic and inorganic complex salts, as disclosed in a number of patent applications, e.g. in US 2,399,083, 2,448,060, 2,540,068, 3,367,778.

To stabilize the photographic dispersions of our invention, conventional stabilizers against fogging during aging or fogging during processing at higher temperatures can be used, such as those disclosed in U.S. Patents 2,444,605, 2,444,606, 2,450,397, 2,713,541, 2,708,161.

The photographic dispersions of the invention can be spectrally sensitized and can be used with conventional hardeners, development activators and waxes, as disclosed in a number of patents, e.g., U.S. Pat. Nos. 2,444,389 and 3,046,132.

Water-insoluble and water-soluble color-forming cyan, magenta and yellow components, DIK and DiB components, as described, for example, in patent documents: US 3,341,331 and 2,875,057, can be used in the photographic dispersions according to the invention.

Coatings of photographic color positive materials according to the invention are carried out on conventional barytated paper substrates or on laminated paper substrates with or without a reflective layer.

The advantage of the color positive substrates according to the invention is the possibility of reducing the silver content per area while maintaining the maximum optical density of the individual layers D _aax , maintaining

243387 4 values of the mean gradient 0 and the values of the sensitivity S and haze D _# , compared to classically prepared photographic dispersions and a reduction in investment requirements, requirements for operation, measurement and regulation compared to dispersions prepared by double-jet precipitation.

The attached figure shows the microcrystal size distribution curves of the dispersions prepared in the following examples.

Example 1

Comparative dispersion prepared in the classical way - dispersion A

Solution I water dist. KBr NaCl RhCl ₃ 0.001% gelatin 212 ml ’,415 g 12.89 S 0.4 mi; 1.56 g Solution II science of dest. 206ml AgN0 ₃ 14.06 grams and Solution III distilled water 103 ml _AgNO3 6.86 grams i

After heating solution I to 45 °C, solution II was added for 30 min. A short maturation period followed, followed by the addition of solution III over 1 min. The microcrystal size distribution curve is shown in Fig. 1 (curve a).

The dispersion was stabilized with 1-phenyl-5-aercaptotetrazole and 6-methyl-4-hydroxy-1,3,3a,7-tetraazaindene.

Example 2

Comparative dispersion prepared by crystallization with constant pAg - dispersion B

Solution I dist. water NaCl gelatin 300 al 1.75 3 e g Solution II Ag«> ₃ water daat.de 21.23 125 alt g Solution III KBr 1.48 8 NaCl 6.57 8 science dest. to 125 alt

After heating solution I to 55 C, solutions II and III were simultaneously added to it so that the pAg value of the reaction mixture was 9.1 + 0.1. The pAg value was maintained by a constant flow rate of solution II and a regulated flow rate of solution III. 1

The microcrystal size distribution curve is shown in Fig. 1 (curve h). The dispersion was stabilized in the same manner as in Example 1. ;

Example 3 >

Dispersion according to the invention - dispersion C

Solution I water deat. HaCl gelatin 115 ali 1.41 9.35 g g Solution II AgHO-j 21.23 g water deet. to 250 ml Solution IH KBr 1.89 g HaCl 7.59 g CdCl ₂ 2.5 ^0 RhCl ₃ 0.001 % 0.82 g 0.4 al

After heating solution I to 51 °C, solutions II and III were simultaneously added to it so that the addition time of solution III was 10 to 15% longer than that of solution II. The pAg value was not regulated; its approximately the same value was maintained during the reaction by an excess of haloalcohol.

The distribution curve of microvessels is shown in Fig. 1 (curve g). The narrow distribution is due to the presence of Cd ⁺⁺ ions. The dispersion was stabilized by the same means as in example f.

Example 4

Dispersion according to the invention - dispersion D Solution X water deat. 150 alt HaCl ’ g gelatin 8 grams Solution II Ag» ₃ ’6.9g T1MO ₃ 0.538 grams water deat. to 100ml IH solution KBr 1.44 grams HaCl 5.72 grams dist. water to 110 a

After heating solution I to 50 °C, solutions II and III were simultaneously added to it so that the addition time of solution III was about 5 to 10% longer than that of solution II. The pAg value was not regulated, but maintained by an excess of hall salts.

The distribution curve of the microcrystals is identical to Example 3. The narrow distribution is due to the presence of Ti* ions. Stabilization was carried out in the same way as in Example 1.

The photographic dispersions from Examples 1 to 4 were cast onto glass plates so that the Ag content on the plate was 6 g/· ² · After exposure, the plates were exposed and processed in a metol-hydroquinone developer for 6 min at 20 °C. The results obtained are shown in Table 1.

Table 1

Dispersion A Dispersion B Dispersion C Dispersion D ^D ain ^_D eup 0.03 0.01 0.01 0.01 ^D. « 4.9 5.9 5.8 5.85 Q 4.5 6.2 6 6 relative sensitivity 100 92 100 95

It is clear from the results that dispersions C and D, prepared according to the invention, have parameters similar to dispersion B, prepared by complex controlled crystallization, and highly exceed the parameters of comparative dispersion A, prepared by the classical method.

The photographic dispersions obtained from examples 1 - 4 were sensitized with 3-allyl-3'-ethyl-4'-5'-diphenyl-4-keto-5-(1''-ethyldihydroquinonylidone-4' '-ethylidene)thiazolino-thiazolocyanine bromide and the color component 1-hydroxy-2-(hexadecenylamino)-4-sulfonephthalene. After adding coating additives and hardeners, coating was carried out on a baryta paper base. The coatings were sensitized and processed according to the following procedure:

1. Developer - 5 min at 20 °C

hydroxyl aainaulfate 1.2 and H-ethyl-N-(β-hydroxyethyl)-1 ,4-dlaainoben- dream 4.5 in sodium hexametaphosphate 2 grams potassium carbonate 75g sodium sulfate 0.5 , potassium broald 0.5 , water daat. to 1,000ml

2. Washing - 0.5 min

3. Interrupting and fixing bath - 4 min at 20 °C

Ingredients: Sodium Chloride 200 10 25 1,000 sodium sulfite potassium dihydrogen sulfide water daat. do B-Slicing and fixing bath - 5 min at 20 °C Ingredients: chelaton 3 5 iron chelate!toaodny 50 sodium carbonate 2 sodium sulfate 15 sodium thiosulfate 150 thioacetic acid 2 dist. water to 1,000

5.

6.

Washing - 15 min

Stabilization bath - 1 min at 20 °c Composition: sodium acetate formaldehyde (40*) distilled water to

000

I am young.

The results obtained are presented in Table 2.

table 2 Ag/ ^a2 content contents of folder/s ² ®ain ^D sup ^Dmax About relative S Dispersion A 0.8 0.44 0.09 2.3 3 100 Dispersion B 0.4 0.41 0.07 2.4 3.1 94 Dispersion C 0.4 0.41 0.07 2.3 3 100 Dispersion D 0.4 0.41 0.07 2.3 3 97

It is clear from the table that the dispersions prepared according to the invention allow achieving the same or improved parameters of the color positive material with a significantly reduced Ag/m ² content compared to classically prepared dispersions.

Claims (4)

OF THE INVENTION 1. A process for preparing chlorine-silver-silver photographic dispersions for color positive materials and low silver content, characterized in that the dispersion is precipitated by the simultaneous inflow of silver nitrate and halide salt solutions into an artwork containing an aqueous colloidal medium without measuring the pAg of the reaction mixture and subsequent control the amount of feed solutions where the desired morphology and dispersion parameters are achieved by the presence of a salt of Cd, Pb, Zn, TI or B1 in the reaction mixture. 2. The process according to claim 1, wherein the bromide content of the dispersions is in the range of 3 to 30%, preferably 8 and 16%. 3. Process according to claim 1, characterized in that the amount of Cd, Pb, Zn, TI or Bi salts in the precipitation of the dispersions is in the range of 0.001 to 0.1, preferably 0.01 to 0.0, mol per mol of silver. 4. The process of claim 1, wherein the Cd salt is cadmium chloride, bromide, or cadmium iodide, the Pb salt is Pb, the Zn chloride salt is Z, the thallium nitrate salt T1, and the bismuth nitrate salt Bi.