US3765897A

US3765897A - Process of incorporating additives into photographic emulsions

Info

Publication number: US3765897A
Application number: US00187554A
Authority: US
Inventors: F Nittel
Original assignee: Agfa Gevaert AG
Current assignee: Agfa Gevaert AG
Priority date: 1970-10-09
Filing date: 1971-10-07
Publication date: 1973-10-16
Anticipated expiration: 1990-10-16
Also published as: BE773584R; FR2113006A6; JPS5424290B2; DE2049689A1; JPS53131028A; GB1370151A

Abstract

The emulsification of additives into a photographic emulsion is stabilized by combining the additive with mono aryl esters or mono cycloalkyl esters of a succinic acid that has a long chained aliphatic substituent.

Description

United States Patent [1 1 [111 3,765,897 Nittel Oct. 16, 1973 PROCESS OF INCORPORATING [58] Field of Search 96/100, 97, 84, 114.5

ADDITIVES INTO PHOTOGRAPHIC EMULSIONS [56] References Cited Inventor: Fritz Nittel, Cologne, Germany Agfa-Gevaert Aktiengesellschaft, Leverkusen, Germany Filed: Oct. 7, 1971 Appl. No.: 187,554

Assignee:

Foreign Application Priority Data Oct. 9, 1970 Germany P 20 49 689.3

US. Cl 96/100, 96/84, 96/97,

96/1145 Int. Cl G03c 1/40 UNITED STATES PATENTS 3,689,271 9/1972 Nittel et al 96/100 Primary Examiner-Norman G. Torchin Assistant Examiner-Richard L. Schilling Attorney-Arthur G. Connolly et al.

10 Claims, No Drawings PROCESS OF INCORPORATING ADDITKVES llNTO PHOTOGRAPHIC EMULSKGNS The present invention relates to a process for incorporating substances in materials which are used to form photographic layers and auxiliary layers.

It is already known that emulsifiable compounds such as color couplers, UV absorbers, white toners and similar additives may be incorporated in gelatin solutions by using so-called oil forming agents. According to U.S. Pat. Nos. 2,322,027 and 2,533,514, for example, color couplers used in the production of photographic products are incorporated in emulsions by dissolving the color coupler in an organic liquid of relatively high boiling point which is insoluble in water, and emulsifying or dispersing the solution in the emulsions. This process has the disadvantage that hydrophilic developers, e.g., N-butyl-N-w-sulphobutyl-pphenylenediamine, penetrate the oil droplets only to a slight extent, if at all. This causes loss in sensitivity, flattening of the gradation and a reduced image density. Also residues of hydrophobic developer may be retained in the droplets and cause fogging when the photographic material is treated in oxidizing bleaching baths.

l-lydrophilic substances such as color couplers which carry a carboxyl group are incorporated in gelatin in the form of their sodium salts. Since the gelatine solutions are subsequently adjusted to a pH of 6.2 to 6.5, these compounds are generally present in microcrystalline distribution. The protective colloidal action of gelatin is in many cases insufficient, so that recrystallization occurs influencing sensitivity, gradation and color brilliance in an uncontrollable manner.

Although hydrophilic substances such as color couplers which carry SO H groups are generally more compatible with gelatin than the above mentioned compounds, recrystallization still occurs in manycases during digestion of the gelatine, especially in the case of compounds that have an enolate form which promotes solubility in an alkaline medium. At the pH values of 6.2 6.5 to which most emulsions are adjusted, the action of the S Na group in preventing recrystallization is no longer sufficient. This again leads to a loss in sensitivity, reduction in the color brilliance and loss in gradation. The use of lithium salts and increased amounts of wetting agents has been found to also bring no significant improvements.

Numerous hydrophilic substances of the above mentioned types, moreover, have the property of increasing the viscosity of the casting solution,- in some cases to such an extent that such solutions can no longer be worked up. i

It is an object of the present invention to provide an incorporation process which does not have the above mentioned disadvantages.

In our patent application Ser. No. 814,808, now U.S. Pat. No. 3,689,271, filed Apr. 9, 1969 there have been descirbed compounds of the general formula wherein R means asaturated or unsaturated alkyl radi cal of at least five carbon atoms and Q possibly contains the group COX, with Xhaving various meanings.

These compounds are said to prevent crystallization and to favor the coupling of oxidized color developers, especially of hydrophilic oxidized color developers. I now have found new compounds which are even more useful in emulsifying additional substances such as color couplers, UV absorbents, white toners or stabilizers in hydrophilic binders for photographic layers.

The compounds according to the present invention correspond to the formula:

The following compounds have proved to be e555 cially suitable:

din-c 0 oQ-om (mixture 0 and p) DOC-( 3H:

din-o o O E The above long chained aliphatic radicals are generally isomeric mixtures. In addition to the alkyl radicals represented in the examples, which in most cases contain one unsaturated bond, hydrogenated alkyl radicals HO O C-CH-CnHzv Hr-COOQCHO ClsHJs-CH-C O OH Hz-CO O c m-ores o 011 cal-coo- CmHw-CH-GO OH xiasi w v s th San .s

The compounds according to the invention are prepared by reacting suitable phenols or'cyclohexyl alco- .hols with long chained substituted succinic acid anhydride in a known manner, preferably in the presence of acid or' basic catalysts, such as sulfuric acid or pyridine. In this reaction, the succinic acid anyhdride ring is opened with formation of an ester bond and a carboxyl group. Products in which the long chained radical is in the d-pOSltlOl'l to the carboxyl group and those in which it is in the fi-position to the carboxyl group are formed side by side. For the sake of simplicity, only one of these forms is represented in the general formula and in the examples, but the invention is not thus limited to hi .99, 9L1-, m r

in cases where the compounds according to the invention contain several substituted succinic acid radicals, these are preferably the same radicals although in principle the cyclohexyl or aryl alcohols could be reacted with mixtures of variously substituted succinic acid anhydrides to yield compounds which contain vargusspqsivis a i radicals lly} stribv The process according to the invention is generally carried out as follows:

Substances which are capable of being emulsified, e.g., color couplers, UV absorbents, white toners, stabilizers or developers, are dissolved in an organic solvent which is immiscible with water, together with the compounds which are to be used according to the invention and the resulting solution is emulsified in the casting solution for the photographic layer by means of an if The compounds form soaps in alkaline pH ranges, in

other words, in the course of development. In contrast to lower carboxylic acids or those which have only a short fatty acid radical, the compounds described here are not washed out in an alkaline medium. They, therefore, prevent precipitation of the dyewhich is formed in the coupling reaction, and the occurrence of uneven colour surfaces. The crystallization of color couplers, which may otherwise already occur during the process of digestion, is also prevented. Furthermore, in contrast to the known hydrophobic oil-forming agents, the compounds used according to the invention cause neither flattening of the gradation nor a reduction in the image.

density. They also largely prevent the increase in viscosity which many color couplers containing COOH or SO l-l groups cause in the process of digestion.

The compounds according to the invention have the following advantages over the compounds described in patent application Ser. No. 814,808.

The tendency to crystallization of the substances which are to be emulsified is even more effectively suppressed so that even substances which have a very high tendency to crystallize may be emulsified without recrystallization taking place. When compounds to be emulsified are emulsified in the presence of the compounds according to the invention, only slight clouding of the wet layers is observed. The refractive index is practically the same as that of dry gelatin so that no opalescence occurs. This is paricularly important when UV absorbents, e.g. those of the benzotriazole type, are used in the protective layer over color photographic materials. If the auxiliary substances according to the invention arenot used, the opalescence is so severe that the black parts of the image have a bluish appearance.

The compounds described here are generally used in the proportion of 0.1 to parts by weight for each part by weight of the substance which is to be incorporated, the proportion being preferably within the range of 0.3 to 1 part by weight. The higher concentrations of up to 10 parts by weight are useful for those cases' in which only small quantities of additive, e.g., a stabilizer, should be introduced into the casting solution. Examples of particularly suitable organic solvents which are not miscible with water are chlorinated short chained aliphatic compounds, e.g., methylene chloride, as well as ethyl acetate and diethyl carbonate.

The binder used for the photographic layers is preferably gelatin although this may be partly replaced by other film-forming natural or synthetic polymers, e.g., alginic acid and its derivatives such as its salts, esters or amides, earboxymethyl cellulose, alkyl cellulose, starch and its derivatives, polyvinyl alcohol, copolymers containing vinyl alcohol and vinyl acetate units, polyvinyl pyrrolidone and the like, anionic polyurethanes and other latices, e.g., copolymers of acrylic acid esters, acrylonitrile or acrylamide.

The photographic layers may contain all the known 5 additives such as anti-fog agents, stabilizers, hardeners, plasticizers and wetting agents. Furthermore, they may be both chemically and spectrally sensitized.

The light-sensitive emulsions may be chemically sensitized by carrying out the ripening process in the pres- 10 ence of small quantities of compounds which contain sulfur, for example allyl isothiocyanate, allyl thiourea or sodium thiosulfate, or they may be sensitized by means of the compounds described in Belgian Pat. specifications Nos. 493,464 and 568,687, the iminoaminomethane sulfinic acid compounds described in Belgian Pat. specification No. 547,323, or small quantities of noble metal compounds such as compounds of gold, platinum, palladium, iridium, ru-

thenium and rhodium. The emulsions may also be sensitized with polyalkylene oxide derivatives, elg., polyethylene oxide having a molecular weight of between 1,000 and 20,000, condensation products of alkylene oxides and aliphatic alcohols, glycols, cyclic dehydration products of hexitols, alkyl-substituted phenols, aliphatic carboxylic acids, aliphatic amines, aliphatic diamines and amides. The condensation products have a molecular weight of at least 700, and preferably more than 1,000. These sensitizers may, of course, be combined in order to obtain special effects, as described in Belgian Pat. specification No. 537,278 and in British Pat. specification No. 727,982.

EXAMPLE 1 NHCOCHzO-QCtHn sHn and 20 g of Compound 7 dissolved in 160 cc of ethyl acetate are emulsified in 1 kg of a 10 percent gelatine solution at C. 'After removal of the solvent in a thin layer evaporator, the emulsion is added to 1 kg of a red sensitized silver halide gelatine emulsion which contains 0.33 mol of silver bromide, 0.0075 of silver iodide 50 and g of gelatine per kg.

The resulting mixture is used within a colour photographic multilayered material in the usual manner as a red-sensitive layer which contains. cyan-forming coupier.

Flattening of the gradation and reduction in the image density which are caused by the known hydrophilic developers do not occur in this case.

EXAMPLE 2 40g ofthe following cyan-forming coupler:

and g of Compound 12 are together emulsified in l kg of a 10 percent gelatin solution as described in Ex ample l. The emulsion is added to 1 kg of a red sensitised silver halide gelatine emulsion described in Example l. 5

The same results are obtained after the mixture has been worked up as described in Example 1.

EXAMPLE 3 g of the following magenta-forming coupler:

in 1 kg of a 10 percent gelatin solution as described in Example 1 and added to 1 kg of a green sensitised silver halide gelatin emulsion.

The mixture is worked up as in Example l. The green-sensitive layer with regard to gradation and density shows the properties described. in Example 1.

EXAMPLE 4 3 8 of fel wesllw figi s N rHu and 10 g of Compound 25 are dissolved in ethyl acetate and emulsified in 1 kg of a 10 percent gelatin solution. The emulsion is cast as a UV protective layer over a color photographic material.

The protective layer prepared by the process accord- ,ing to the invention is clear, whereas a layer which has awareness! .wiflzww npqsss 2229315 9951 1;-

EXAMPLE 5 30 g of the UV absorbent used for Example 4 and 15 g of Compound 8 are dissolved in ethyl acetate and emulsified in 1 kg of a 10 percent gelatin solution. The emulsion is cast as a UV protective layer over a color photographic material. The result is similar to that obtained in Example 4.

EXAMPLE 6 g of the following white tonerz W on. I as N \N 0 C t isHtr-CHC O OH and 2.5 g of Compound 20 are dissolved in 10 ml of ethanol and 10 ml of methyl chloride and emulsified in 1 kg of a 10 percent gelatin solution. The emulsion is cast as the uppermost protective layer over a color photographic material in which one of the lower protective layers is a UV protective layer. The fluorescence of the white toner is in no way impaired and no crystallization occurs.

EXAMPLE 7 The UV absorbent of Example 4 is dissolved in ethyl acetate and portions of this solution separately mixed the following oilformers:

I c rH1 -CHC 0 0H CH:C0O-C9Hl0(i50) (from Serial No. 814,808)

CuHrCH-C O OH CH1C 0 O-GgHn (from Serial No. 814,808)

A... COO@ (compound 31 of this application) (compound 27 0! this application) Each solution is poured on a glass plate and the solvent i is evaporated. The Table indicates when crystallization of the UV absorbent occurs.

TABLE oil-former added crystallization to 1 part of UV absorbent observed after no addition 5 minutes [.5 parts of! 45 minutes 2 parts of l 2 hours 1.5 parts of l] 1 hour 2 ports of ii 2 hours 1.5 parts of ll! no crystallization after 24 hours 2 parts of Ill no crystallization after 24 hours 1.5 parts of N no crystallization after 24 hours 2 parts of IV no crystallization after 24 hours I claim:

1. in the process of emulsifying materials into an aqueous dispersion of a hydrophilic photographic binder with an oil former that stabilizes the emulsion, the improvement according to which the oil former has l esmuiaa RCHCOOH R- H-COwO-R' wherein one R is hydrogen and the other is a saturated or unsaturated straight chained or branched aliphatic radical having six to 18 carbon atoms, and R a cycloalkyl group, an aryl group or a heterocyclic aromatic group. bg m i ati of la m. tiwh qhtbshin i solved in a volatile water-immisicible short chain aliphatic solvent along with the oil former, and the solution thus formed is emulsified into the gelatin emulsion.

3. The combination of claim 2 in which the organic solvent is methylene chloride.

4. The combination of claim 2 in which the organic solvent is diethyl carbonate.

5. The combination of claim 1 in which the binder is gelatin, the material to be emulsified is soluble in aqueous alkali, and is dissolved in an aqueous alkaline solution along with the oil former and the resulting solution emulsified into the gelatin emulsion.

6. In a photographic gelatin emulsion containing emulsified photographic additive particles and an oil former that stabilizes the emulsion, the improvement according to which the oil former has the formula:

wherein one R is hydrogen and the other a saturated or unsaturated straight chained or branched aliphatic radical having six to 18 carbon atoms, and .w R a cycloalkyl group, an aryl group or a heterocyclic aromatic group. 7. The combination of claim 6 in which R is substit led with another radical of the formula:

R-CH-COOH 9. The combination of claim 6 in which the photographic additive is a UV absorber.

10. The combination of claim 6 in which the photoa white toner.

IIK i l graphic additive is

Claims

2. The combination of claim 1 in which the binder is gelatin and the material to be emulsified is first dissolved in a volatile water-immisicible short chain aliphatic solvent along with the oil former, and the solution thus formed is emulsified into the gelatin emulsion.
3. The combination of claim 2 in which the organic solvent is methylene chloride.
4. The combination of claim 2 in which the organic solvent is diethyl carbonate.
5. The combination of claim 1 in which the binder is gelatin, the material to be emulsified is soluble in aqueous alkali, and is dissolved in an aqueous alkaline solution along with the oil former and the resulting solution emulsified into the gelatin emulsion.
6. In a photographic gelatin emulsion containing emulsified photographic additive particles and an oil former that stabilizes the emulsion, the improvement according to which the oil former has the formula:
7. The combination of claim 6 in which R'' is substituted with another radical of the formula:
8. The combination of claim 6 in which the photographic additive is a color coupler.
9. The combination of claim 6 in which the photographic additive is a UV absorber.
10. The combination of claim 6 in which the photographic additive is a white toner.