US2875050A - Triaminopyridine developer - Google Patents

Description

TRIAMINOPYRIDINE DEVELOPER Gershon M. Goldberg,

Lexington, Mass., Incorporated, Burlington, Mass, a corporation of Delaware r Arlington, and James E. Lu Valle,

No Drawing. pplication December 16, 1957 Serial No. 702,759 1 9 Claims. (Cl. 96-66) This invention relates to the art of photography and assignors to Technical Operations,

more particularly to the development of. thelatent silver image in exposed photographic emulsions.

The principal object of this invention is to provideimproved photographic development with solutions which are more active than hydroquinone and which have a lower fog level than p-methylaminophenol (Elon) or 1,2,4-benzenetriamine. tion is to provide superadditive developing solutions which comprise new mixtures of active developing agents.

In a brief summary of this invention, these objects are achieved by the method of developing photographic film which comprises treating an exposed silver halide emulsion with a solution of 2,3,6-triaminopyridine. The developing solution preferably comprises 2,3,6-triaminopyridine,

' an anti-oxidant, an alkali and an anti-fogging agent dis solved in water and preferably has a 10 and 11. added to the triaminopyridine developer solution greatly increases the speed of the solution while the addition of small amounts of triaminopyridine to conventional hydroquinone solutions forms a superadditive developer wherein the speed and maximum density are greatly increased and the gamma raised.

The following description illustrates developers according to this invention.

A typical developer solution according to the invention is as follows:

pH between about 2,3,6-triaminopyridine mo1e 0.025 Water to make 2 liters.

In the above solution the active developing agent is the triaminopyridine while the carbonate, bromide and sulfite serve their usual function as an alkali, a restrainer or antifogging agent, and preservative or anti-oxidant respectively. Other alkali, anti-oxidant, and anti-fogging agents well known in the developer art can also be employed.

Strips of Plus X film'of the Eastman Kodak Company were exposed through a standard step-wedge and developed in a standard Jarrell-Ash processing unit. The results of these tests are indicated in Table I below. In this table the 2,3,6-triaminopyridine is abbreviated TAP and was used in the formula disclosed above. The other tests indicated were also run with the same formula excepting that the particular developer indicated in each test was substituted for the triaminopyridine. In each of these tests an unexposed strip of the same film was processed alongside the exposed test strip as a control and to determine the fog level. The time of development was eight A further object of this inven- 1-phenyl-3-pyrazolidone (Phenidone) minutes and the temperature of the developer solutions was 68 F. After processing the densities were determined for each of the exposure steps and H and D curves were plotted. The speed was taken as the antilog (3lo g E at D=0.2 above (fog-l-base).

2,875,050 Patented Feb. 24, 1959 Table II below illustrates the development obtained by TAP alone and in combination with other common de: veloping agents. The pH of each developingsolutionwas 10.5 and the development time was eight minutes. The developing solutions contained the materials initially indicated except that the developers indicated in Table II replaced the triaminopyridine in the amounts stated. These data show that the combination of Phenidone andTAP produces an appreciable speed increase. With Eton, TAP appears. to inhibit the developing activity of the Elon. When a small amount of hydroquinone is added to a TAP developer, the combination appears to produce only a small improvement. However, in TAP-hydroquinone combinations wherein the hydroquinone is the major molar ingredient, a superadditive developer appears to result. According to these data the speed and maximum density of hydroquinone are doubled and the gamma is Table III below indicates the development obtained with TAP developing solutions with various development times. TAP developing solutions of this concentration appear to have an induction period of about four minutes before development becomes evident. This induction period is not as long as that observed with hydroquinone since the same concentration of hydroquinone produces the first visible development in about eight minutes. Table III shows that TAP in this concentration produces adquate development in about eight minutes but that development for sixteen minutes is optimal. With the long developing times TAP becomes quite compares very favorably with other high energy developers.

Increasing the concentration of TAPfrom 0.025 to 0.050 M produces a large speed increase. Further iucreases in concentration produce relatively small efiects. In the absence of bromide ion, the speed of development energetic and its action increases" from pH 9 to pH 11 and then falls otf sharply -at--pH 12. 1 In the-presence of a-rnoderatoconcentration of bromide ion (up to 0.02 M) TAP develops best at about pH 10. Higher pHs cause a sharp rise in the fog level. The presence of larger concentrations of bromide ions suppresses-development with TAP developer solutions as well as with hydroquinone solutions up to about pH 1 0.5. The proper pH range for TAP developing solutions is thus about to 11.

'As-illustrated by the foregoing data, tests indicatethat TAP is ,similar'vto hydroquinoneiin its action and is generally a Strongerdeveloping agentt 2,3,6-triaminopyridine together with methodsfor its preparation are disclosed in United States Patent No. 2,136,044. 7

It. should, be u derstood that. the. toregqing...d isclosureis torthe pu p s o i l tr tiq eulysand t at t vent in udes a mod fi ati n .talliugr i l i thes qpe of t appende i l im "W cla m;

Th m hod o d e nfp q r ph .fi mtwh comprisesv treating an exposed silver halide emulsion with a solution of 2,3,6-triaminopyridine,

t 2. The method according toclaim 1 wherein said solu- ;tion has apH between about 10v and 11.

3. The method of developing. photographic filmvwhich comprises treating anexposed silver halide. emulsion with 4 V V a solution of 2,3,6-triarninopyridine and l-phenyl-S-py- --razolidone.

4. The method of developing photographic film which comprises treating an exposed silver halide emulsion with a solution of 2,3,6-triaminopyridine and hydroquinone.

5. A developing solution for exposed photographic silver halide emulsion which comprises 2,3,6-triaminopyridine,- an anti-oxidant, an alkali,--andamend-fogging agent dissolved in water.

6. A developing solution according ,to claim 5 which as pHb w n abou 10 an tll- 7. A developing solution for exposed photographic silver halide ,pernulsio-n which comprises t2,3,6l-ttriaminopyridine, sodium sulfite, sodiumcarbonate, and sodium bromide dissolved in water, said solution having a pH between about IO- and 11.

8. A developing solution for exposed photographic silver halide emulsion which comprises 2,3,6-tria tninopyridine and '1-phenyl'-3-pyrazolidone dissolved in water, 9. -A superadditive developing solution 'for exposed photographic silver halide emulsion which comprises 2,3;6-tr-iaminopyridine and hydroquinone dissolvedin water, 4 said-hydroquinone exceeding in moi percent the amount of the triaminopyridine.

No references cited.

Claims (1)

1. THE METHOD OF DEVELOPING PHOTOGRAPHIC FILM WHICH COMPRISES TREATING AN EXPOSED SILVER HALIDE EMULSION WITH A SOLUTION OF 2,3,6-TRIAMINOPYRIDINE.