US2371740A - Developers containing silver halide solvents - Google Patents

Description

Fatente be a, Bearing and Charles Henry Gnell, Rochester, N. Y, assignors to Eastman Kodak Company, Rochester, N. Y.,

New Jersey This invention relates to photographic developers and particularly to addition agents for de- I velopers.

It is well known that sulfltes are usually added to photographic developing solutions for the purpose of preventing aerial oxidation or the developing agent. In addition to their action in this way, sulfltes also have a slight solvent action on silver halides and as development progresses they actually dissolve a small quantity of each silver halide grain and thereby minimize the tendency for clump formation which would increase'graininess. This solvent action is especially useful in reversal processes and, in fact, an additional silver halide solvent is ordinarily used in the negative developer. If some other silver halide solvent is not used, the development will beso low that the reversal highlights are not cleaned out and are heavy or dense in the final image.

Not all silver halide solvents have the most favorable properties for use in negative developers. These solvents should accomplish the primary purpose of cleaning out the reversal high lights without dissolving the unexposed silver halide.

1 This means that in the ordinary negative development the silver halide should be completely reduced in the fully exposed areas and the silver halide solvent helps to accomplishthis purpose. These solvents should not produce an unsually great amount of latent imagegrowth. That is, they should not develop silver halide to any great extent in the "regions surrounding the exposedportions. A further efiect which should'b'e absent in the solvents is that of fogging .thefilm in the unexposed portions. As a result or the eflects which a silver halide solvent should produce, and for reasons not fully understood, they should help to improve the resolving power and definition of the image and in a color process should improve the color saturation and brightness of the final image. Other effects which the 1 solvent should produce are an increase in penetration of the developing agent, important in the development or multi-layer,materials, a reduction in grain size and an improvement in resolu- -tion at the edges of the image.

Silver halide solvents such as hypo. ammonia and thiocyanates have hitherto been used in phoa corporation of Application March 20, 1942, Serial No. #35528 1 Claims. (CI. 95-88) tographic developers, but do not meet all therequirements listed above. Hypo tends to produce fog unless the concentration is very carefully adiusted and ammonia is difllcult'to maintain in solution and undesirable to-use on account/of its high vapor pressure. The thiocyanates tend to produce latent image growth and do not improve resolving power and definition.

Lower aliphatic amines such as ethylamine, div ethylamine and ethanolamine have been used in both the negative developer and the color developers of color reversal processes but they, too. are not completely satisfactory for various reasons. These compounds are not so good with respect to solvent action, reduction of latent image growth, resolving power and definition as are the compounds of our invention.

- It is therefore 'an'object of the present invention to "provide novel silver halide solvents, for photographic developers. A'further object is to provide addition agents for photographic developers which will produce less latent image growth and change of color balance on reversal than silver halide solventshitherto used. A still further object is to provide novel addition agents for photographic developers which give improved photographic characteristics such as resolvingpower and definition.

These and other objects are accomplished by incorporating in a photographic developing solution a primary or secondary aliphatic amine having' an aliphatic carbon chain of from 3 to 7 carbon atoms. According to the preferred form or our invention, these amines are incorporated in V the negative developer of a reversal process, especially a coloru'ever'sal process, for improving the photographic characteristics referred to above.

The developer ordinarily used as the negative or first developer in a reversal process is an MQ" developer, that is, one which contains mono-' methyl-p-aminophenol sulfate and hydroquinone in varying proportions. Other developing agents may, howevenbe used and the developing soluf tion may-contain the usual ingredients such as sulflte, carbonate, bromide etc. .To these developing solutions we addthe amines in varying amounts usually from'slightly less than 1 gram to about 10 grams per liter of developer. It will be understood that the amines may be used in the developers of a negative-positive process, that of a reversal process.

The following compounds are suitable for use according to our invention:

CH1=CHCH1NH1 Allyl amine CHFCHCH:

CH:=HCH:

Diallyl amine NH: H: crncmcnon 1,3-diamino propanol Hr-C HzCHaQHr-NH:

Propylene diamine CHiCHaCHrNH: n-Propylamh'ie OHNH;

C H: Isopropylamine N H: C H O H G Ht- H I lHiOH 3-amino-2-mcthyl-L3-propanediol NH; N H: HPCHICHIHOH 1,4-dlamino butanol CHsCHzCHiCHzNH:

n-Butylamine GHsCHaCHsCH:

I s I NH orncrncnicm I v Ibi-n-butylamine NH: CHiCHiHCHsQfl I 2-amino-1-butanol cmcn omcnicnilvm I I nmylsmine CHsCHzCHsCHaCH: I

NH lcineincmcrncni Diainylamine NH: "QH Clif-L-fHCHaCHiCHI B! "1 ml oamem tahermo m cmcmunomcno cnt H u C ii-aniinoi-heptnliol These compounds may be used in varying amounts depending upon theirsolvent' activity.

example, 2-amino-1-butanol is less active than butyl amine or isopropyl amine presumably because the polar hydroxyl group, near the silver solvent amino group has reduced its solvent activity.

We have found that the following range of concentrations is suitable with the compounds listed above.

We have also found that improved results can be obtained by using mixtures of the amines; a

lower molecular weight amine to give required definition and lack of fog while a small amount of a higher molecular weight amineis added to give the necessary complete development by in greater silversolvent action. A satisfactory mixture is 5 grams per liter of isopropylamine with 2 grams per liter of butylamines It may also be I pH which we have generally found best in negative developers is -10 to 11.5 as compared with The straight chain'iatty amines are usually the most eil'ective and, in general, the compounds with the longer chains are more active unless some side chain interferes with thev activity. For

Example 1, I A negative developer for the reversal process the following composition:

Monomethyl-p-aminophenol sulfates a 7 ygrams-.. 6 Hydrqqlflnbne do 3 eodiumsumte do 655 Sodium carbonate.. do 17.5 Potassium bromide "do"... 1.25 S-nitroindazole (1 A%tsolution) cc 3.5 n-Butylamine grams 2.5 Water o u Q er" 1 The pH is adjusted to about 10.5 by adding approximately advantageous to mix these amines with inorganic silver halide solvents such as thiocyanate or ammonia. i I

An important condition which we have discovered and perhaps accounts for the reason that a good many of these amines have hitherto been.

to 10 for thiocyanate The pH for negative developers shouldnot be greater than 11.5, however, .or the developer is likely to produce fog.

Ordinarily most of these amines are watersoluble to the extent to which they are required for solvent action. In a few instances we have had to dissolve them in alcohol to bring them into solution. p

The following examples illustrate the developers compounded according toour invention.

10 cc. of 9,20% solution of sodium hydroxide.

Example 2 The following solution is used as a negative developer in the reversal process:

Monomethyl-p-aminophenol sulfate grams; 6

Hydroquinone -do 3 Sodium sulfite -do- 55 Sodium carbonate..- ..-do 17.5

Potassium bromide -do-.. 1.25

Isopropylamine ..do---- 3.5

Water in er... 1

Example 3 The following developer'ls suitable for the formation of a color image by direct development:

A. Diethyl-p-phenylenediamine hydrochlo- We have referred principally to the use of the amines to which our invention relates. in the first developer of a reversal process. However, they may also be used to advantage in the second developer of a reversal process, whether black and white or color, or in the single developer used in a negative process. either black and white or color, or in the single developer used to make a positive print on paper from a negative, either black and white or in color.

Where color development is used. the usual type of coupler compound reactive with the development product of the developing agent to form a dye, may be employed. Such coupler compounds usually have a reactive methylene or phenolic 'hydroxyl group with which the developer reacts.

In general, all of the primary and secondary aliphatic amines, having a carbon chain within the range specified, are satisfactory silver halide solvents. Amide derivatives such as urea and acetamide, dicyan diamide and ethyl methyl carbamide have no silver halide solvent properties in photographic developers of the type we use. Secondary alkylolamines, such as diethanolamine, likewise have little solvent action. We believe that the activity of the amines which we have found suitable for use as silver halide solvents is controlled to a large extent by surface activity, molecular structure and atomic arrangement. The amide derivatives such as acetamide and urea are not solvent reactive because oxygen is more strongly attracted to silver halide than the amine group and the solvent activity of such compounds is, therefore, reduced or eliminated.

It is to 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 negative photographic developer for the reversal process containing a developing agent and as a silver halide solvent, 9. non-fogging amount, from about A to about 10 grams per liter of an amine selected from the group consisting of primary and secondary alkyl, alkylene and allylamines having a carbon chain containing from 3 to 7 carbon atoms and containing no hydroxyl group.

2. A negative photographic developer for the reversal process containing a developing agent and as a silver halide solvent 3. non-fogging amount, from about to about 10 grams per liter of an alkyl amine having a straight chain alkyl group of from 3 to 7 carbon atoms and containing no hydroxyl group.

3. A negative photographic developer. for the reversal process containing a developing agent and as a. silver halide solvent a non-fogging amount, from about V gram to about 10 grams per liter of an amine selected from the group consisting of primary and secondary alkyl, alkylone and allylamines having a carbon chain of three carbon atoms and containing no hydroxyl group.

4. The method of improving the photographic characteristics of a positive photographic image produced by the reversal method, which comprises incorporating in the negative developer of the reversal rocess as a silver halide solvent a non-fogging amount of amine selected from the group consisting of primary and secondary alkyl, alkyiene and allylamines having a carbon chain'containing from 3 to 7 carbon atoms and containing no hydroxyl group.

matic amino coupling developing agent and a non-fogging amount of an'amlne selected from the group consisting of primary and secondary alkyl, alkylene and allylamines having a carbon chain containing from 3 to '7 carbon atoms, and having, a pH not greater than 11.5, and simultaneously coupling the development product of said developing agent with a coupling compound reggtive with said development product to form a e.

6. The method oi improving the photographic characteristics of a silver image produced by a single development step, which comprises developing an exposed gelatino-silver halide layer in a developing solution containing a silver'halide developing agent and a non-fogging amount of an amine selected from the group consisting of primary and secondary alkyl, alkylene and allylamines having a carbon chain containing from 3 to 7 carbon atoms and containing no hydroxyl