US2901350A - Combined developers and fixers - Google Patents

Description

United States Patent C) COIVIBINED DEVELOERS AND FIXERS Jerome Stewart Goldharnmer, Levittown, N.Y..

No Drawing. Applicationctober'12, 1954i- Serial No. 461,929

1 Claim. (Cl. 96-61) This invention relates to chemical compositions for combined developing and fixing of silver halide photographic emulsions.

Formulas of the types disclosed in Goldhammer and Maurer U.S. Patent 2,782,120, and Goldhammer U.S. Patent 2,782,121, both issued February 19, 1957, and each entitled Combined Developer and Fixer are markedly superior to the combined developers and fixers of the prior art in all significant photographic properties. Nevertheless, there are occasions when the moderately fine-grained results produced by the formulas of the first application are not entirely adequate, and the use of formulas based on the second application (while producing sufliciently fine-grained results) cannot be considered, either because the objectionable ammonia odor exlsts, or because of the loss of activity upon continuous exposure to the air, due to loss of ammonia.

The objects of this invention are to producecombined developers and fixers capable of yielding fine-grained images in films developed and fixedtherein, and at the same time to eliminate the disadvantages of objectionable odor and deterioration of the combined developer and fixer containing ammonium thiosulfate upon exposure to the air. i l

Combined developing and fixing baths .of' high activity, compounded with sodium thiosulfate as a fixing agent produce negatives that are not as. fine-grained as are given by the special fine grain developer formulations of the prior art. This is believed to be due to the. relatively slow. fixing action of sodium thiosulfate, which permits development to proceed until clumping of the grains occurs. The substitution of ammonium thiosulfate, with its more rapid fixing action, considerably reduces, the graininess of negatives so processed, as compared to negatives of the same density and contrast produced by combined fixing and developing baths that are similar in composition except for the use of sodium thiosulfate rather than ammonium thiosulfate. The use of ammonium thiosulfate also makes it possible to compound a bath of low total salt content, which, as is explained in the second patent referred to above, is a condition favorable for obtaining exceptionally high activity. By high activity is meant a rapid rate of development and the ability to produce good effective emulsion speed in the films processed; I

Since this bath must bei'alkaline to: secure sufiicient developing activity, some free ammonia is liberated. When the solution is stored in a sealed vessel, it rapidly reaches an equilibrium state at the moderate alkalinity normally employed. Even in a deeptank, the loss of ammonia is so slow that no serious deteriorationof the bath occurs. However, under such conditionsas shallow tray use, prolonged storage in'poorly cappedbottles, elevated room temperature, or low atmospheric pressure (as encountered in aircraft or at high altitudes), significant retaining the excellent stability of such baths.

Patented Aug. 25, 1959 "ice lated. quarters, even a slightevolution of ammonia gas may be objectionable.

The present invention improves upon the graininess of images produced by the, sodium thiosulfate formula described in the first of the above identified patents, while At the same time, it has a'low total salt content comparable to that of the ammonium thiosulfate baths, thus producing; high development rates at moderate alkalinity.

The increased activity obtained by reducing the salt content of the combined developing and fixing bath may be seen by comparing the first formula given by way of example in the first of the above identified patents, with the second example in the present application. Theformula referred to above in the Goldhammer and Maurer patent employs sodium thiosulfate as the fixing essing time of 6 minutes at 68 degrees F. The bath prepared in accordance with the present invention, using ethanolamine in combination with sodium thiosulfate, and having the same quantities of the same developing agents, has a salt content of grams per liter and a pH of 9.3, and gives, with the same film, a gamma of 0.90 in a processing time of 5 minutes at 68 degrees F.

Except for the addition of sodium thiocyanate to the latter formula, which due to its silver solvent action prevents grain clumping, but also reduces developing activity, the two baths differ only in the combinations of chemicals used as alkali and fixing agent, and in the resulting salt content and pH. Since the bath prepared in accordance with the present invention gives a higher gamma in a shorter time and at a lower value of pH, in spite of the presence of the sodium thiocyanate, the comparative results show how strongly reduction of the total salt content favors higher activity.

The fixing time with the present formulas is only slightly increased from that of the ammonium thiosulfateformulas, and appreciably better than that of the sodium thiosulfate formulations. The exhaustion capacity is likewise much improved over that of the sodium thiosulfate formulations, and almost equal to the exhaustion capacity of the ammonium thiosulfate formulas.

The present invention consists in using primary amines: in a combined developing and fixing bath, in conjunction with a developing agent of the amidol type, or other active developing agent, with or withouta density building agent, a preservative, an anti-foggant, and sodium thiosulfate.

By the term developing agents of the amidol type I refer to a class of developing agents in which more than; two activity-conferring hydrcxyl (--OH) or amino (-NH groups are attached to a single benzene ring.

This includes agents which have one hydroxyl and two amino groups (as does amidol itself) as well as others in which there are three amino groups. In addition to their. chemical structure these agents are characterized by the fact that they develop in acid solutions as well as in neutral of alkaline solutions, whereas the great majority of developing agents are inactive in acid solution.

Amidol is the only member of this class that is manufactured in quantity and commercially available at the present time. The literature, however, records numerous other examples of this class of developing agents which have been found to have characteristics. similar to those of amidol. Specific examplesv are the following compounds:

NH; (Amidol) 2,4, diaminophenol 2,4, diaminoresorcinol G-methyl 2,4, diaminophenol S-methyl 2,4, diamlnophenol on onrgavn-o H3 Jr-amino-6-methy1-2-methy1amino-phenol GE -III- CH -dimethylamino-2-methylamino-phenol i Um.

NHZ

1,2,4 triaminobenzene N H: 5-methyi 1,2,4 triaminobenzeuev N H @NH: NH: -4 hydroxy; 2 ,4 diaminodiphenylamine NHg- I V ONH: NH:

4',2',4 triaminodiphenylamine 1,3 diamino 4,6 dihydroxybenzene The primary amines which may be employed are:

Ethylamine, C2H5NH2 Ethanolamine, CHgOHCH NH Ethylenediamine, NH CH C-H NH These compounds are' similar in action to the ammonium ion, insofar as their effect on fixation is concerned. That is to say, fixing agents are formed in situ from the sodium thiosulfate and one of the above men tioned primary amines much in the manner of the formation of ammonium thiosulfate in fixingbaths containing sodium thiosulfate andammonium chloride. (See chapter 17, Fixation and Washing, paragraph 3, pp. 718 720, of The Theory of the Photographic Process, by C. E. KennethMees, Revised Edition, 1954.) However these primary amines difler in important respects from ammonia itself. First, they are practically odorless in the concentrations employed. Second, even in very high concentrations, the odor is not objectionable. Third, because of the increased molecular weight, vapor pressure is much reduced, so that loss by aeration or evaporation is so slight that failure upon standing in open vessels occurs only through oxidation of the developing agents, as is normally the case with conventional developers and combined developer-fixers heretofore described, other than those employing ammonium salts.

In compounding combined developing and fixing formulas of this type, it is preferred to use the primary amines listed above, since they are all highly alkaline, and to'bring the alkalinity down to thedesired point by the use of sodium bisulfite, or potassium metabisulfite (which are, acid salts), in appropriate amounts. In the event that insufficient sulfite ion is present after this has been done, neutral sodium or potassium sulfite may be addedlinthe proper amount. Alternatively, the salts of these primary amines: formed -by reaction with hydrochloric, nitric, sulfuric,- or acetic acid may beused, but in these'cases, someother alkali, such as an alkali metal carbonate or hydroxide must be used, which involves an increase in total salt content and a consequent depressing effect on development activity.

Formulas using the present invention may consist of any active developing agent, an inorganic reducing agent, such as sodium sulfite or sodium bisulfite, sodium thicsulfate, and a primary amine. Depending on the results desired, an organic anti-foggant and a density building organic developing agent may also be employed.

The term, an active developing agent as used herein means a developer of reduction potential of 6.0 or greater in the series proposed by Nietz-Tschibissof. This reduction-potential series is given as Table IH, page 338, chapter XI, Developers and Theory of Development of the Handbook of Photography, by Henney and Dudley, 1939.

Density building developing agents as used herein, may be defined as developing agents having a reduction potential of less than 6.0, listed by the same source.

While most of the examples given below employ amidol as the initiating agent, it should be understood that the present invention is in no sense limited to this class of developing agents. Any of the active developing agents such as pyrogallol, Metol (mono methyl para amino-phenol sulfate), Phenidone (1 phenyl-3 methyl-5 pyrazolidone), Kodelon (para aminophenol hydrochloride) used alone or in conjunction with a density-building agent, such as hydroquinone, chlorhydroquinone, catechol or glycin, will also produce useful results.

Some typical formulas using the present invention follow:

(1) A fine-grain formula, for the processing of miniature camera films, using ethylene diamine:

Water (80 F.) ('0 750 Sodium bisulfite gm 50 Amidol 2m 85-88% ethylene diamine cc 32 0.5% 6-nitrobenzimidazole cc 40 Hydroquinone gm 3.3 Sodium thiocyanate gm 10 Sodium thiosulfate (anhydrous) gm 60 Water to make 1000 cc. pH=8.5. Time, 7 min. 68 F. Gamma, 0.55 on medium speed panchromatic film.

(2) A medium-grain formula, for the processing of high and medium speed panchromatic roll and sheet films, exposed by electronic flash illumination, using ethanolamine:

Water to make 1000 cc. pH=9.3. Time, 5 min. 68 F. Gamma, 0.90 on medium speed panchromatic film.

(3) A rapid processing formula, intended for the processing at elevated temperatures of special pre-hardened films:

Water (90 F.) cc 750 Sodium sulfite, desiccated gm 50 Sodium bisul'fite gm 20 Amidol gm 15 Hydroquinone m 5 Glycin gm 10 /2 6-nitrobenzimidazole cc Sodium thiosulfate (anhydrous) gm 54 Ethylene diamine 88% "cc" 60 Water to make 1000 cc.

pH=10.5. Time, 2 sec. 85 F.

Gamma, 0.60 on special pre-hardened motion picture negative film.

(4) A rapid processing formula for purposes similar to No. 3, using Phenidone as the initiating agent:

Water F.) cc 750 Phenidone gm 2 Sodium sulfite, desiccated gm 25 Chlorohydroquinone gm 6 Glycin gm 6 Sodium thiosulfate (anhydrous) gm 10 Ethanolamine cc 20 Water to make 1000 cc.

pH=l0.5. Time, 5 sec. 85 F.

Gamma, 0.6 on special pre-hardened motion picture negative film.

(5) A high contrast formula for press photographs using pyrogallol as the developing agent:

Water (80 F.) cc 750 Pyrogallol um 10 Sodium sulfite, desiccated gm 25 Sodium thiosulfate (anhydrous) gm 50 Ethylene diamine 85-88% cc 20 Water to make 1000 cc. pH=l2.2. Time, 4 min. 68 F. Gamma, 1.5 on medium speed panchromatic film.

What is claimed is:

In a chemical composition for combined developing and fixing of silver halide photographic emulsions, the combination of sodium thiosulfate and ethylene diamine with 2,4, diaminophenol and p-hydroxyphenylaminoacetic acid.

fifth edition, 1952, page 224. (Copy in Division 67.)