US2735765A - Ch-chs - Google Patents

Description

United States Patent O BIHYDROQUINONE ANTISTAIN AGENTS Anthony Loria, Paul W. Vitturn, and Arnold Wcissberger,

Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application June 3, 1953, Serial No. 359,423

7 Claims. (Cl. 95-6) This invention relates to color photography and particularly to a method for preventing the formation of color fog or stain in photographic emulsions.

The method of color photography in which color-forming or coupler compounds combine with the development product of aromatic amino photographic developers to produce dyes is well known. The color formers or couplers may be added directly to the emulsion layers or may be incorporated in the developing solution as described in Fischer U. S. Patent No. 1,102,028, granted June 30, 1914, or they may be incorporated in a waterpermeable medium which is insoluble in the carrier for the sensitive silver salt as described in Mannes and Godowsky U. S. Patent 2,304,940, December 15, 1942, and Jelley and Vittum U. S. Patent 2,322,027, granted June 15, 1943.

A difliculty frequently encountered in these processes is the formation of color fog or stain. When the exposed material is developed in a color-forming developer, dye fog is frequently formed in the emulsion layer. This is because the developing agent has been oxidized to some extent by the action of the air and the oxidized developer tends to couple with the color-forming compound at places in the photographic material where no silver image is produced. It is well known that in these processes the dye should beformed only where the silver halide is reduced to metallic silver, thereby oxidizing the developing agent to a form which couples with the color former. Once the developing agent is oxidized, it couples immediately with the color former whether a photographic image is present or not. Aerial oxidation of the developer or oxidation by means other than the photographic image therefore converts the developer to a form which will immediately react with the color former to produce a color fog on stain. This effect is especially noticeable in materials having couplers incorporated in the sensitive layer since there is no coupler in the developing solution to react with any developing agent which is oxidized by the action of the air. Fog or stain arising from these causes is not readily controlled by the same procedures used to control silver fog.

The control of color fog or stain by incorporating, hydroquinone or certain of its derivatives in photographic emulsions is described in Vittum and Wilder U. S. Patent 2,360,290, granted October 10, 1944. Hydroquinones described therein include diamyl hydroquinone and dioctyl hydroquinone. The dialkyl hydroquinones available at that time were the di-secondary and di-tertiary hydroquinones such as 2,5-di-tertiary octyl hydroquinone. This compound has good stain preventing properties whenincorporated in photographic color films but it suffers from the disadvantage when used in silver halide emulsion layers of causing instability of the color developed dye to heat or light.

It is therefore an object of the present invention to provide antistain agents which cause lessinstability of the color developed dve image to heat and light. A further object is to provide antistain agents which are easily compatible with and non-difiusing in the colloid of the photographic layer in which they are incorporated. A further object is to provide antistain agents which are non-diffusing in the photographic layer and which are strong enough reducing agents to react rapidly with oxidized color de- 5 veloper. A further object is to provide antistain agents which do not form highly colored oxidation products when the material containing them is put through an oxidizing bath. Other objects will appear from the following description of our invention.

These objects are accomplished by the use in an emulsion layer or other layer of a photographic material especially a silver halide emulsion layer in which a colored image is formed by development in a color forming developer, of a bihydroquinone having the formula OR OR The following compounds are illustrative of those which We may use:

1. 7 OH OH Blhydroquinone on on me. 04m

on. on;

'2,2-methylene bis(5-tert.butyl-4-methoxyphenoll OH OH at r 018E" 2,2'-methylene bis-5-n-octadecyl hydroquinone 4. 0 CH: 0 CH:

i Ha'lC 1 CisHn CH3 on,

1,1'-methy1ene bis(2,5-dimethoxy-4-octadecyl benzene) OH l 2,2-isobutylidene bis- (4) -meth0xypheno1) Ha C 4 I C 411 C H3 8) C H3 0 C H 2,2-isobutylidene bis-(-tert.butyll-methoxyphenol) 7. OH 0H 1 OH O H p-p'-Biphenylene-bis- (aminomethyl hydroquinone) The preparation of the compounds of our invention will now be described:

1. This compound was prepared as described by Hale and Robertson in the Am. Chem. 1., 36, 693 (1908).

2. A mixture of 180 g. (1 mole) of 3-tert-butyl-4- methoxyphenol, 300 ml. of benzene, 20 g. of calcium chloride, 20.8 g. (.25 mole) of 36% formalin, 3 ml. of concentrated hydrochloric acid, and 5 drops of thioglycollic acid was stirred at room temperature for several hours; then heated at reflux for one hour. Water was added and the organic layer was washed free of acid. The solvent was removed and the residue distilled in a high vacuum. The fraction boiling at 212-215 C/ 0.4-0.6 mm. was collected and crystallized, first from hexane, then three times from aqueous acetic acid. The product melted at 174.5-177.5 C.

3. This compound was prepared by demethylating 1,1- methylene bis(2,5-dimethoxy-4-octadecylbenzene) with AlC13 in boiling dry benzene. Aluminum chloride 20 g. (fine powder) g. of the dimethoxy intermediate, and 200 ml. of dry benzene were refluxed on a steam bath with eflective mechanical stirring for 20 hours. The cooled reaction mixture was poured into 1500 ml. of cold methyl alcohol, and the solid obtained was crystallized twice from ethyl acetate, using carbon decolorizing the first time. There was obtained 5.5 g. of colorless material (going pink on standing), having a melting point of 190-191 C.

4. This compound was prepared by the method of Jacini and Bacchetti as described in Gazz. 80, 760-761 (1950). Crystallized from tetrahydrofurfuryl alcohol the product is a colorless solid melting at 88-89 C.

The 2,5-dimethoxy octadecylbenzene intermediate for the above preparation is described by Cook, Heilbron, and Lewis in the J. Chem. Soc., 659-661 (1942).

5. This compound was prepared by the method given for 2,2-isobutylidene bis(5-tert-butyl-4-methoxyphenol) substituting 4-rnethoxyphenol for 2-tert-butyl-4-methoxyphenol.

6. This compound was prepared by the method given for 2,2-methylene bis(5-tert-butyl-4-methoxyphenol), substituting isobutyraldehyde for formaldehyde. The product is a white crystal line material melting at 181.5- 183.5 C.

7. A mixture of 13.8 g. gentisaldehyde and 9.2 g. benzidine were refluxed in 300 ml. of n-butanol for 15 minutes. On cooling an orange precipitate formed. The precipitate was filtered, washed first with 50 ml. of butanol and then with 250 ml. of ethanol. Yield: 16 g. The material gets brown at about 200 C. and does not melt up to 260 C.

The 4,4'-bis(2,5-dihydroxybenzalamino)diphenyl prepared above was reduced in dioxane solution, using Raney nickel as a catalyst and 40-50 pounds of hydrogen pressure at 60-65 C. The catalyst was removed from the hot solution by filtration and the solution cooled. The product formed was filtered, washed with a small volume of fresh dioxane, and crystallized twice from the same solvent. The (2,5-dihydroxybenzyl)benzidine was obtained almost colorless but turned light brown in the open air. It melts at 198-200 C.

The antistain agents of our invention are useful, in general, with emulsions containing couplers incorporated in the manner described in Mannes and Godowsky U. S. Patent 2,304,940 or Jelley and Vittum U. S. Patent 2,322,027.

Couplers such as those described in Weissberger U. S. Patent 2,298,443 and Salminen and Weissberger U. S. Patent 2,423,730, when incorporated in this way, produce dyes upon color development which are prone to fading by the action of visible or ultraviolet light, when known antistain agents such as 2,5-di-tert. octyl hydroquinone are used in the emulsion layer. These are the yellow and cyan dyes. The magenta dyes, such as those formed from couplers described in Loria, Weissberger and Vittum U. S. Patent 2,600,788 are relatively little affected by the known antistain agents upon the action of light.

In order to illustrate the eflect of our antistain agents, the following test was made.

A quantity of the antistain agent the molar equivalent of 0.05 g. of 2,5-di-tert. octyl hydroquinone, was dissolved with 0.5 g. of coupler in 1.5 cc. of dibutylphthalate. To this solution was added 11 cc. of 10% gelatin solution and 2.8 cc. of 5% alkanol B (sodium alkyl napthalene sulfonate) solution. The resulting mixture was passed through a colloid mill three times, and to the resulting dispersion, 32 cc. of a gelatino-silver halide emulsion were added, and the mixture blended and coated on a film support so that the antistain agent was equivalent to 5 mg. per square foot of 2,5-di-tert. octyl hydroquinone.

Two check coatings were made: One containing no antistain agent, and one containing 5 mg. per square foot of 2,5-di-tert. octyl hydroquinone.

The film strips were exposed on a Ib sensitorneter using a silver wedge varying in density from 0 to 3. They were then developed 10 minutes at 68 F. in the following developer:

G. 2-amiuo-5-diethylamino toluene HCl 2 Sodium sulfite (desiccated) 2 Sodium carbonate, monohydrate 20 Potassium bromide 2 Water to 1 liter This was followed by 5 min. in the following stop bath:

Sodium sulfite, desiccated g Acetic acid (28%) cc 235 Boric acid, crystals g 37.5 Potassium alum g 37.5

Water to 1 liter After washing, bleaching in ferricyanide-bromide, fixing in 30% hypo solution and again washing, the wavelength-density curves for each coating were read before and after exposure to visible and ultraviolet light. The loss of density at the maximum of the wavelength-density curve after exposure in the Fade-O-Meter for 6 hours and comparison with the check coatings under similar conditions indicated the effect of the agent under test. The following table shows these results:

Loss in density at maximum absorption Agent Cyan Dye Yellow Dye Check (none) 0 0 2,5-di-tert. octyl hydroquinone 21 13 Compound 1 .02 01 C mpound 2. .04 .01 Compound 3. 01 02 Compound 4. 0 01 Compound 5 0 02 Compound 6 02 03 Compound 7 0 07 These results show that all of the agents cause less fading of the cyan and yellow dyes than that caused by 2,5-di-tert. octyl hydroquinone. Compounds 4, and 7 caused no more fading of the cyan dye than the check coating without antistain agent, and compounds 1, 6 and 7 caused even less fading of the yellow dye than the check coating free of antistain agent, that is, these cornpounds caused some increase in density of yellow dye as well as improving antistain properties.

Another compound useful as an anti-stain agent in photographic emulsions is 2-p-cyanophenyl-2-imidazoline.

The antistain agents of our invention may also he used in non-sensitive overcoating or filter layers, such as a colloidal silver interlayer of multilayer photographic material. In general, the antistain agents of our invention are used in the emulsion or other layer in quantities ranging from 0.07 gram to 4.3 grams per liter of emulsion or gelatin solution. These values are, however, merely illustrative.

In certain cases the antistain agents of our invention may be incorporated in a processing solution such as a prebath, first developer bath, or color-forming developer used with color film which is developed with a primary aromatic amino developing agent.

Our materials are particularly useful with color-forming emulsions coated on paper supports where it is espe cially important to reduce the minimum or fog densities. This applies both to negative developed paper and to reversal paper as well as to transparency materials.

It will be understood that the examples and modifications described herein are illustrative only and that our invention is to be taken as limited 'only by the scope of the appended claims.

We claim:

1. A color-forming photographic emulsion having reduced fogging tendency, comprising a silver halide emulsion having incorporated therein a non-diffusing coupler compound capable of coupling with the oxidation product of a primary aromatic amino developing agent and as an antistain agent a bihydroquinone having the formula (BR OR where R is selected from the class consisting of hydrogen and a methyl radical, R is selected from the class consisting of hydrogen and a methyl radical, X is selected from the class consisting of hydrogen and amino group and an alkyl group having from 1 to 18 carbon atoms, and Z is selected from the class consisting of methylene, isobutylene and N,N'-dimethylenebenzidine groups and a single chemical bond.

2. A color-forming photographic emulsion having reduced fogging tendency, comprising a silver halide emulsion having incorporated therein a non-difiusing coupler compound capable of coupling with the oxidation prodduct of a primary aromatic amino developing agent and as an antistain agent a bihydroquinone having the formula (I)H OH OH OH in which R is an alkyl group of from 1 to 18 carbon atoms.

3. A color-forming photographic emulsion having reduced fogging tendency, comprising a silver halide emulsion having incorporated therein a non-diffusing coupler compound capable of coupling with the oxidation product of a primary aromatic amino developing agent and as an antistain agent a bihydroquinone having the formula CH; OCH:

in which R is an alkyl group of from 1 to 18 carbon atoms.

4. A color-forming photographic emulsion having reduced fogging tendency, comprising a silver halide emulsion having incorporated therein a non-diffusing coupler compound capable of coupling with the oxidation product of a primary aromatic amino developing agent and as an antistain agent a bihydroquinone.

5. A color-forming photographic emulsion having reduced fogging tendency, comprising a silver halide emulsion having incorporated therein a non-diffusing coupler compound capable of coupling with the oxidation product of a primary aromatic amino developing agent and as an antistain agent 2,2-methylene bis(5-tert. butyl-4-methoxyphenol.

6. A color-forming photographic emulsion having reduced fogging tendency, comprising a. silver halide emulsion having incorporated therein a non-ditfusing coupler compound capable of coupling with the oxidation prodnot of a primary aromatic amino developing agent and as an antistain agent 2,2-methylene bis-S-n-octyl hydroqumone.

7. A color-forming photographic emulsion having reduced fogging tendency, comprising a silver halide emulsion having incorporated therein a non-diffusing coupler compound capable of coupling with the oxidation product of a primary aromatic amino developing agent and as an antistain agent 1,1'-methylene bis(2,S-dimethoxy-4- octadecylbenzene).

References Cited in the file of this patent UNITED STATES PATENTS

Claims (1)

1. A COLOR-FORMING PHOTOGRAPHIC EMULSION HAVING REDUCED FOGGING TENDENCY, COMPRISING A SILVER HALIDE EMULSION HAVING INCORPORATED THEREIN A NON-DIFFUSING COUPLER COMPOUND CAPABLE OF COUPLING WITH THE OXIDATION PRODUCT OF A PRIMARY AROMATIC AMINO DEVELOPING AGENT AND AS AN ANTISTAIN AGENT A BIHYDROQUINONE HAVING THE FORMULA