US3713827A

US3713827A - Process for the development of photographic material

Info

Publication number: US3713827A
Application number: US00078937A
Authority: US
Inventors: J Willems
Original assignee: Agfa Gevaert NV
Current assignee: Agfa Gevaert NV
Priority date: 1969-10-27
Filing date: 1970-10-07
Publication date: 1973-01-30
Anticipated expiration: 1990-01-30
Also published as: BE757905A; GB1326358A; JPS4946939B1; FR2065923A5; DE2052694A1

Abstract

A METHOD OF DEVELOPING EXPOSED PHOTOGRAPHIC SILVER HALIDE ELEMENTS IS DESCRIBED ACCORDING TO WHICH AN AQUEOUS ALKALINE COMPOSITION IS USED IN THE PRESENCE OF AN ANIONIC SILVER HALIDE DEVELOPING AGENT AND A DIQUATERNARY CYCLIC AMMONIUM SALT WHICH BY THE UPTAKE OF 1 ELECTRON FORMS STABLE WEITZ RADICALS. THE DIQUATERNARY CYCLIC AMMONIUM SALTS ACCELERATE DEVELOPMENT AND THE DEVELOPMENT ACCELERATING EFFECT SURPASSES THAT OF RELATED QUATERNNARY AMMONIUM COMPOUNDS THAT DO NOT FORM STABLE WEITZ RADICALS.

Description

United States Patent 3,713,827 PROCESS FOR THE DEVELOPMENT OF PHOTOGRAPH'IC MATERIAL Jozef Frans Willems, Wilrijk, Belgium, assignor to Gcvaert-Agfa N.V., Mortsel, Belgium No Drawing. Filed Oct. 7, 197.0, Ser. No. 78,937 Claims priority, application Great Britain, Oct. 27, 1969, 52,569/ 69 Int. Cl. G03c 5/30 US. Cl. 96-663 7 Claims ABSTRACT OF THE DISCLOSURE A method of developing exposed photographic silver halide elements is described according to which an aqueous alkaline composition is used in the presence of an anionic silver halide developing agent and a diquaternary cyclic ammonium salt which by the uptake of 1 electron forms stable Weitz radicals. The diquaternary cyclic ammonium salts accelerate development and the development accelerating efiect surpasses that of related quaternary ammonium compounds that do not torm stable Weitz radicals.

This invention relates to the development of photographic materials containing exposed silver halide in the presence of substances influencing the development.

It is known that certain chemical compounds such as 1-aryl-3-pyrazolidinone compounds, p-phenylenediamine derivatives and p-aminophenol derivatives which used alone are poor developers for photographic silver halide emulsions, become much more efl'ective when used in conjunction with other developers such as hydroquinone, hydroquinone derivatives, ascorbic acid, etc. the efi'ect being known as superadditivity. Though the compounds used in practice are effective superadditive developers, they still present a number of difliculties. For instance, some compounds such as 1-phenyl-3-pyrazolidinone, which is widely used as superadditive developing agent in conjunction with hydroquinone, is subject to hydrolysis in alkaline medium whereas other compounds, when used in concentrated aqueous solutions that should be diluted before use, have insuflicient solubility.

It is further known that onium compounds such as quaternary ammonium, quaternary phosphonium and ternary sulphonium compounds are able to accelerate photographic development by agents which act as doubly or more highly charged negative ions for instance hydroquinone, hydroquinone derivatives, ascorbic acid, etc., whether as an additive to the developer or to the emulsion. However, the development accelerating eifect of the onium compound is lower than that of the above superadditive developing agents.

In accordance with the present invention a new class of development accelerators of the quaternary ammonium type with specific redox properties is provided, which a not subject to hydrolysis in alkaline medium, have a high water-solubility and are very effective accelerators of photographic development by doubly or more highly charged negative developer ions as well as by the singly ionized developer anions of hydroxylamine and derivatives thereof.

Patented Jan. 30, 1973 The novel accelerators of photographic development by negatively charged developing agents, of use in accordance with the present invention, are characterized as being diquaternary cyclic ammonium compounds which by the uptake of 1 electron form stable Weitz-radicals.

Particularly suitable development accelerators according to the present invention are the diquaternary dipyridinium, dithiazolium and diimidazolium salts and the diquaternary pyridiniumthiazolium and pyridinium-imidazolium salts represented by the following general formula:

each of Z and Z (the same or different) stands for the atoms necessary to complete a pyridinium, thiazolium or imidazolium nucleus optionally carrying fused on aryl nuclei such as benzthiazolium, benzimidazolium and quinolinium and further substituents such as alkyl and aryl A stands for a chemical bond linking the 2-position 0f Z =pyridinium, thiazolium or imidazolium to the 2- position of Z =pyridinium, thiazolium or imidazolium or to the 4-position of Z =pyridinium or for a chemical bond linking the 4- position of Z =Z =pyridinium, each of R and R stands for alkyl including substituted alkyl or R together with R may stand for ethylene including substituted ethylene when A is a chemical bond linking the 2-position of Z to the 2-position of Z2, and X'- stands for an anion or acid radical for example halide, p-toluene sulphonate, alkyl sulphate or perchlorate.

1 1.. Hz Q PREPARATION l: COMPOUND 3 21.2 g. (0.1 mole) of 2-(4-pyridyl)benzothiazole and 250 g. (2 moles) of dimethylsulphate are heated for 5 hours at 1 C. on an oil bath. The precipitate formed upon cooling is filtered by suction and washed with diethyl ether. Yield: 40 g. Melting point: 190 C.

PREPARATION 2: COMPOUND 4 5 g. (0.025 mole) of 1,10-phenanthroline monohydrate and 20 ml. of dibromoethane are refluxed for 1 hour whereupon the precipitate formed is recrystallized from ethanol/water. Yield: 3 g. Melting point: 260 C.

PREPARATION .3 COMPOUND 5 6.8 g. (0.025 mole) of l-pheny1-2-(2-pyridyl)benzimidazole and 20 ml. of dibromoethane are refluxed for 1 hour whereupon the precipitate formed is recrystallized from ethanol. Yield: 5 g. Melting point: 260 C.

PREPARATION '4: COMPOUND 6 10.6 g. (0.05 mole) of 2-(2-pyridyl)benzthiazole and 9.4 g. (0.05 mole) of dibromoethane are heated for 48 hours at 130 C. in a sealed tube whereupon the residue is boiled with acetone. Yield: 4 g. Melting point: 260 C.

Thus, in accordance with the present invention there is provided a process of making photographic records which comprises treating a photographic material having layers containing developable silver salts with an aqueous alkaline solution in the presence of a negatively charged developing agent and a diquaternary salt as described above. The invention also includes developer compositions comprising in addition to a negatively charged developing agent, a diquaternary salt as described.

The diquaternary salts of use according to the present invention may be added to the developing bath or to the emulsion or to both simultaneously, the developing bath being preferred however.

The accelerating eifect of the compounds according to the invention is not restricted to certain types of negatively charged developing agents. It is apparent with all developing agents the ionized forms of which in alkaline medium carry one or more negative charges. These developing agents including among others hydroquinone, hydroquinone derivatives, ascorbic acid, sodium dithionite addition products of sodium dithionite and formaldehyde, as Well as hydroxylamine and hydroxylarnine derivatives.

The use of hydroxylamine and derivatives as developing agents has been disclosed among others in U.S. Pat. 2,857,276. The oxidation products of these hydroxylamine developing agents have the favourable property of leaving no residual stain in the silver image obtained. Hydroxylamine itself is less suitable for use as developing agent because it can give rise to fog but the N,N-dialkylhydroxylamines such as N,N-diethylhydroxylamine and the heterocyclic N-hydroxylamines such as N-hydroxymorpholine, N-hydroxypiperidine and N-hydroxypyrrolidine disclosed in the above U.S. patent are particularly suitable. Other hydroxylamine derivatives that have been proposed for use as silver halide developing agents and of which the development activity is higher than that of the N,N-dialkyl hydroxylamines include for example aminoalkyl hydroxylamines, more especially N,N-dialkylhydroxylamines having in at least one of the N-alkyl groups an intralinear amino nitrogen atom, either cyclic or acyclic, examples of which can be found in U.S. Pat. 3,287,125, alkoxyhydroxylamines, more especially N,N-dialkylhydroxylamines of which at least one of the N-alkyl groups is substituted by alkoxy or alkoxyalkoxy, examples of which can be found in U.S. Pat. 3,293,034, and sulphone hydroxylamines, more especially N,N-dialkylhydroxylamines having in at least one of the N-alkyl groups an intralinear sulphonyl SO group, examples of which can be found-in U.S. Pat. 3,287,124.

The developing bath may comprise in addition to the anionic developing agent any of the common ingredients employed in developing compositions, e.g., alkalies such as sodium hydroxide, potassium hydroxide, sodium carbonate, trisodium phosphate etc., silver halide solvents such as sodium thiosulphate, sodium thiocyanate and cyclic imides such as barbiturates or uracils, preservatives such as sulphites, bisulphites, metabisulphites and acids such as boric acid and citric acid. Further the developer composition may comprise potassium bromide and watersoftening agents such as polyphosphates and derivatives of ethylene diamine tetraacetic acid, antifoggants such as benzotriazole, S-nitro-benzotriazole and 6-nitrobenzimidazole, wetting agents, developing agents having a superadditive elfect with the anionic developing agent used, e.g., 1-phenyl-3-pyrazolidinone as well as other compounds known in the photographic development technique.

The pH of the baths may vary within wide limits and depends on the kind of developing agent involved and the desired etfect. For instance, in the case of hydroquinone and ascorbic acid the compounds of use according to the present invention have little effect below pH 9 whereas in the case of sodium dithionite the pH may be lower, e.g., pH 8. The optimum pH-value for any developing agent used, can best be determined by some simple tests determining the pH-dependency of the development accelerating eflect. In general the pH is comprised between pH -8 and pH 13.

The amount of cyclic diquaternary ammonium compound used according to the present invention depends on the very compound, on the nature of the colloid binder of the silver halide grains and on the amount and type of silver halide in the emulsion.

The amount of onium compound incorporated into the developing bath can vary between very wide limits and depends on the developing agent used. The optimum concentration for any diquaternary salt of use according to the invention can best be determined by employing a series of concentrations in several batches of the same developer and determining the speed obtained before and after incorporation of the said compound in the usual manner which is of course well known to those skilled in the art. Generally, the onium compound is used in amounts ranging between 0.01 mmole and 20 mmole per litre.

The development acceleration obtained with the products according to the present invention can be combined With a chemical sensitization by means of chemical sensitizing agents such as sulphur-containing compounds, e.g, allyl isothiocyanate, allyl thiourea, or sodium thiosulphate, reducing agents such as the tin compounds described in the Belgian patent specifications 493,464 filed Jan. 24, 1950 and 568,687 filed June 18, 1958 both by Gevaert Photo-Producten N.V., the iminoaminomethane sulphonic acid compounds described in the British patent specification 789,823, filed .Apr. 29, 1955 by Gevaert Photo-Producten N.V., or precious metal compounds such as gold, platinum, palladium, iridium, ruthenium and rhodium compounds.

The products influencing the development according to the present invention can also be used in combination with stabilizing agents for silver halide emulsions, such as mercury compounds and the compounds described in the Belgian patent specifications 571,916 and 571,917 both filed Oct. 10, 1958 by Gevaert Photo-[Producten N.V., and in combination with sensitizing and stabilizing cadmium salts in the light-sensitive material as well as in the developer.

They may further be used in combination with alkylene oxide polymers and condensation products of alkylene oxide. The alkylene oxide compounds may be of various types and include, e.g., those described in the US. patent specifications 1,970,578 by Conrad Schoeller and Max Wittwer issued Aug. 21, 1934, 2,240,472 by Donald -R. Swan issued Apr. 29, 1941, 2,423,549 by Ralph K. Blake, William A. Stanton, Ferdinant Schulze issued July 8, 1947, 2,441,389 by Ralph K. Blake issued May 11, 1948, 2,531,832 by William A. Stanton issued Nov. 28, 1950, 2,533,990 by Ralph K. Blake issued Dec. 12, 1950 and the British patent specifications 920,637 filed May 7, 1959 by Gevaert Photo-Producten N.V., 940,051 filed Nov. 1, 1961 by Gevaert Photo-Producten N.V., 945,340 filed Oct. 23, 1961 by Gevaert Photo-Producten N.V., 991,608 filed June 14, 1961 by Kodak and the Belgian patent specification 648,710 filed June 2, 1964 by Gevaert Photo-Froducten NV.

The development accelerators of the invention may be used in conventional or wet development of silver halide emulsions, in diffusion transfer processes, both dye and silver, in such photographic processes known as stabilization processing wherein it is desired to eliminate or minimize the need for Washing or stabilizing operations in liquid baths subsequent to the formation of the silver print, etc.

In diffusion transfer processes, as is well known in the silver salt which is transferred to the image-receiving material and there reduced to silver to form a positive print. The processing composition normally includes a silver halide solvent, such as sodium thiosulphate, sodium thiocyanate and cyclic imides such as barbiturates or uracils, which forms with silver halide a soluble complex as is well known in the art of forming silver images by transfer, and may also include a film-forming material such as sodium carboxymethyl cellulose or hydroxyethyl cellulose, starch or gum for increasing the viscosity of the composition as, for instance, in the case of in-camera silver complex diffusion transfer processing. As is known in the art of diffusion transfer processing the developing agents may be present in the processing solution and/ or the light-sensitive material and/or the image-receiving material.

In stabilization processing the time-consuming fixing and washing operations are eliminated in order to produce the photographic record in the least possible time, by converting after development, with the aid of stabilizing agents such as ammonium thiocyanate, the unexposed and undeveloped silver halide of the photographic emulsion into colourless light-intensitive compounds that need not be removed by washing.

The following examples illustrate the present invention.

EXAMPLE 1 G. Sodium carbonate 20 Sodium hexametaphosphate 1 Sodium sulphite (anhydrous) 20 Potassium bromide 0.5 Hydroquinone 4.4

Water to make 1 litre (pH 10.4).

Other strips are developed in baths having the same composition as bath A but containing in addition thereto 0.31 mmole of 1,l'-tetramethylene-bis(pyridinium chloride) and 0.31 mmole of dodecyl pyridinium chloride respectively whereas the remaining strips are developed in baths having the same composition as bath A but containing in addition, as listed in Table I, 0.31 millimole of a diquaternary salt according to the above general formula. The densities are determined after a developing time of 10 sec., 20 sec., 30 sec., 1 min., 2 min. and 5 min. and are listed in the following table.

Density after a development time of- Developing bath 10 sec. 20 sec. 30 see. 1 min. 2 min. 5 min.

Bath A 0. 04 0. 04 0. 04 0. 04 0. 06 0. 80 Bath A plus 0.31 111111016 of 1, 1-tetramethylene-bis (pyridinium chloride) 0. 04: 0. 04 0. 09 0. 64 1. l3 2. 79 Bath A plus 0.31 mmole of dodecyl pyridinimn chloride 0- 04 0. 04 04 0. 0? Bath A plus 0.31 mmole of compound 1 0. (157 1. 91 3 Bath A plus 0.31 mmole of compound 2.. 0: 0 o: 31 0' 49 1 07 1 86 3 Bath A plus 0.31 mmole of compound 3-.

1 In this bath comprising a diquaternary ammonium bromide the amount of potassium bromide has been reduced to 463 mg. 5

ative results.

the unexposed silver halide is converted into a complex as to obtain compar- Weitz-radicals.

7 EXAMPLE 2 8 EXAMPLE 4 Strips of a photographic material comprising a lightsensitive silver halide emulsion layer coated on a cellulose triacetate support, are exposed through a grey filter with a Density after a development time oi- Developing bath sec. sec. 30 see. 1 min. 2 min. 5 min.

Bath A 0. 04 0. 04 0. 05 0. 05 0. 06 0. 80 Beth A plus L55 mmole of l, l-tetramethylene-bis (pyridinium chloride). 0.04 0. 04 0. l7 0. 66 1. 21 1. 71 Bath A plus 6.2 mmole of 1, 1-tetramethylene-bis (pyridinium chloride). 0. 07 0.33 0. 55 0. 93 1. 34 1. 64 Bath A plus 1.55 mmole of compound 1 1 0.21 0. 54 0. 87 1. 49 2. 71 3 Beth A plus 6.2 mmole of compound 1 2 0. 33 O. 71 1. 01 1. 76 3 8 1 In this bath containing a diquaternary ammonium bromide, the amount of potassium bromide has been reduced to 316 mg. in order to obtain comparative results.

2 In order to obtain comparative results no potassium bromide has been added to this bath.

These density values confirm the results attained in Example 1.

EXAMPLE 3 Strips of a photographic material comprising a lightsensitive silver halide emulsion layer, coated on a cellulose triacetate support, are exposed through a grey filter with a light-quantity (E) which corresponds to the shoulder part of the density/ log E curve. G. For comparison purposes some of these film strips are Sodium hexamctaphosphate 1 developed at 20 C. in separate developing baths, having S dium Carbonate 20 different pH values and having the following compositions. Trisodi'urn phosphate 20 Sodium hydroxide 2.7 Bath Potassium bromide 0.5 A B C D Ascorbic acid 7 Water to make 1 litre (pH 12). Sodium hexametaphosphate, grams 1 1 1 1 gogium sulphkite (tanhydrous), grams 12g 20 20 20 0 rum me a 0T8 e, I'SIIIS l f carbonate, grgams 20 20 Another strip is developed in a bath having the same y quinone, grams 4.4 4 4 4.4 4.4 com Trisodmm phosDhatemms M 20 4o plosltlon h E b ntaining n addltlon 9.05 lsjogimp hygoxiqg, grams n n 2 3 e f ,1 m hylen 1s(pyrl lmum chlorlde) 0 assium romi e, grams 7 waterto make, me 2 1 E 1 1 W fleas stlll th strlp is v l p d in a bath hav ng the same composition as bath E but containing in addition gg 8%: 0.05 mmole of Compound 1. The densities are determined after a development time of 10 sec., 20 sec., 30 sec., 1 min.

P and 2 min. and are listed in the following table.

Density after a development time of- Developing bath 10 sec. 20 see. 30 sec. 1 min. 2 min.

Bath E Bath E plus 0.05 mmole of 1,1-tetramethylene-bis(pyridinium chloride) Bath E plus 0.05 mole of compound 1 1 0.10 0.18 0: 27 0170 1: 10

1 In this bath comprising a diquaternary ammonium bromide the amount of potassium bromide was reduced to 494 mg. so as to obtain comparative results.

Other film strips are developed in baths A, B, C and D having the same composition as the above baths but comprising in addition 6.2 mmole of Compound 1. In these baths A, B, C and D comprising a diquaternary ammonium bromide no potassium bromide was added so as to obtain comparative results.

The following density values were attained.

Densities obtained after a development time of- Developing bath 1 min. 2 min. 4 min. 8 min. 16 min.

From these results appears clearly that Compound 1 has a markedly higher accelerating effect on development by ascorbic acid than the related 1,1-tetramethylene-bis (pyridinium chloride).

EXAMPLE 5 different pH values and having the following compositions:

Sodium hydroxide, grams" Potassium bromide, grams. Ascorbic acid, grams 1 7 sh p 10 From the results obtained it appears that Compound 1 has a high development accelerating efiect whereas the related 1,l-tetramethylene-bis(pyridinium chloride) inhibits development.

5 EXAMPLE 7 This example is analogous to Example 6 with the difference however that the developing bath now contains as developing agent instead of 4.2 g. of hydroxylamine 10 hydrochloride 5 g. of N-methylhydroxylamine hydro- 1 chloride (bath I). 2 P The results attained are listed in the following table.

Densities obtained after a development time of- Developing bath sec. 20 sec. 1 min. 3 min. min.

Bath I." 0. 04 0. 05 0. 07 O. 60 1 09 Bath I plus 0.5 g. (1.75 mole) of 1,1-tetramethy1ene-b 0. 04 O. 04 0.05 0.32 0. 91 Bath I plus 0.5 g. (1.38 mmole) of compound 1. 0- 04 0. l3 0. 65 2. 28 3 Other film strips are developed in baths having the same composition as the above baths but comprising in addition 1.55 mmole of Compounds 1 and 2.

The density values obtained are listed in the following table.

From these results too it appears that 1,1-tetramethylene-bis(pyridinium chloride) inhibits development whereas Compound 1 has a favourable development accelerating effect.

Densities obtained after a development time of Developing bath 10 sec. sec. see. 1 min. 2 min. 5 min.

Bath F 0. 04 0. 04 0. 04 0. 04 Bath F plus 1.55 mmole of compound 1 1 0. 04 0. 06 0. 13 0. 44 Bath F plus 1.55 mmole of compound 2 0. 04 0. 04 0. 06 0. 80 Bath G 0.04 0. 04 0.04 0.05 Bath G plus 1.55 mmole of compound 1 l 0. 72 0. 86 1. 22 1. 72 Bath G plus 1.55 mmole of compound 2 0.28 0. 0. 78 1. 04

1 In these baths comprising a diquaternary ammonium bromide the amount of potassium bromide was reduced to 316 mg. so as to obtain comparative results.

EXAMPLE 6 ,After exposure of film strips as described in Example 1, each of the film strips is developed at 20 C. in separate developing baths. One of them is developed in a bath H EXAMPLE 8 Densities obtained after a development time of- Developing bath 0 sec. 20 sec. 1 min. 3 min. 5 min.

Bath .1 0.04 0.04 0.04 0.07 0.37 Bath .1 plus 88 mg. (0.31 mmole) of 1,1'-tetramethylene-bis-(pyridinium chloride)- 0. 04 0. 04 0. 04 0. 22 1. 14 Bath .7 plus 500 mg. (1.75 mole) of 1,1-tetramethylene-bis-(pyrrd1mum chloride) 0. 04 0. 04 0.05 0. 43 1. 77 Bath J plus 112 mg. (0.31 mole; of compound 1 0. 04 0. 04 0. 07 1. 14 2. 96 Bath J plus 500 mg. (1.38 mmole of compound 1 0. 04 0.05 0. 27 2. 12 3 containing as developing agent hydroxylamine hydrochloride and having the following composition:

Water to make 1 litre.

Other strips are developed in baths having the same composition as bath H but containing in addition one of the compounds identified in the table below.

The densities obtained after various development times are listed in the following table.

By these results it is shown that Compound 1 has a markedly higher effect on development of diethylhydroxylamine than 1,1'-tetramethylene-bis(pyridinium chloride).

EXAMPLE 9 After exposure of film strips as described in Example 1, each of the film strips is developed at 20 C. in separate developing baths. One of them is developed in a bath K containing as developing agent Rongal HT Type 66 (trade name of Badische Anilin & Soda Fabrik Ludwigshafen, Germany, for an addition product of formal- Densities obtained aiter a development time of- Developing bath 0 see. 20 S90. 1 min. 3 min. 5 min.

Bath H 0. 04 0. 05 0. 34 0. 1. 43 Bath H plus 0.5 g. (1.75 mmole) of l,1-tetramethylene-bis-(pyiidinium chloride) 0. 04 0. 04-. 0. 25 0. 79 1. 03 Bath H plus 0.5 g. (1.38 mmole) of compound 1. 0- 0 09 62 1- 55 2. 11

dehyde and sodium dithionite) and having the following composition:

I wherein:

each of Z and Z (the same or diflierent) stands for Boric acid g 20 the atoms necessary to complete a pyridinium, thia- Borax g 25 zolium or imidazolium nucleus which may be sub- Rongal HT Type 66 (trade name) g 10 5 situated and carry fused-on aryl nuclei, Potassium iodide mg 20 A stands for a chemical bond linking the 2-position of Sodium bisulphite 0.5 g. (pH 8.5) Z =pyridinium, thiazolium or imidazolium to the Water to make 1 litre. the 2-position of Other strips are developed in baths having the same 2=P WP thlazohum or lmldazohum or to composition as bath K but containing in addition 0.05 the PP of mmole of one of the compounds identified in the table 2=PY for chemlc'al llnkmg the below. 4-pos1t1ons of The densities obtained after a development time of 30 1= 2=PY sec., 1 min, 3 min., and 5 min. are listed in the followeach of 1 and 2 Stands for an alkyl group 1 ing table. 15 gether with R may stand for an ethylene group when Densities obtained after a development time of- Developing bath sec. 1min. 3min. 5min.

Bath K 0.04. 0.07 0.30 0.70 Bath K plus 0.05 mmole of compound 1 0.63 1. 21 2. 02 2. 45 Bath K plus 0.05 mmole of 1,1'-tetramethylene-bis(pyrldin ium chloride) 0. O4 0. l0 0. 75 1. 15

These results show that Compound 1 has a higher ac- A is a chemical bond linking the 2-position of Z to celerating effect on development by sodium dithionite the 2-position of Z and than 1,1-tetramethylene-bis(pyridinium chloride). X- stands for an anion or acid radical.

EXAMPLE 10 2. Photographic developingmethod acordmg to clalm 0 1, wherein said development is carried out using as de- A photosensitive element was prepared comprising on a paper support a silver bromoiodide emulsion layer containing per kg. an amount of silver halide corresponding to 60 g. of siliver nitrate.

After exposure, the photosensitive element and an image-receiving element, which comprises a silver receptive layer containing development nuclei dispersed in a matrix of colloidal silica coated on a water-impervious support according to the practice described in U.S. Pat. 2,823,122, were advanced in superposed relationship between a pair of pressure-applying rollers to spread between them in a thin layer the following processing composition:

After a contact period of 36 seconds, the emulsion together with the layer of processing liquid was stripped from the image-receiving element to uncover the positive print.

When using a same developing composition but comprising no Compound 1 the density of the positive print obtained was markedly lower. Moreover, in the presence of compounds better quality transfer images are obtained at lower illumination levels as is the case when using N,N-diethylhydroxylamine alone.

I claim:

1. Photographic developing method which comprises developing an exposed silver halide emulsion layer of a photographic material with an aqueous alkaline composition in the presence of an anionic developing agentand a diquaternary cyclic ammonium salt, wherein said ammonium salt corresponds to the formula:

veloping agent a member selected from the group consisting of hydroquinone, derivatives, ascorbic acid, sodium dithionite, hydroxylamine and hydroxylamine derivatives.

3. Photographic developing method according to claim 1, wherein the said diquaternary salt is present in the developing bath in an amount. comprised between 0.01 mmole and 20 mmole per litre.

4. Photographic developing method according to claim 1 wherein said method is used for making images according to the, silver complex diffusion transfer process.

5. Photographic developing composition for developing an exposed silver halide emulsion layer of a photographic material comprising in aqueous alkaline solution in addition to an anionic developing agent a diquaternary cyclic ammonium compound corresponding to the formula in claim 1.

6. Photographic developing composition according to claim 5 containing per litre from 0.01 mmole to 20 mmole of the said diquaternary ammonium salt.

7. Photographic developing composition according to claim 6 wherein the anionic developing agent is a member selected from the group consisting of hydroquinone, a hydroquinone derivative, ascorbic acid, sodium dithionite,, hydroxylarnine and a hydroxylamine derivative.

References Cited UNITED STATES PATENTS 3,240,810 3/1966 Blout ct a1. 9666 3,241,963 3/1966 Green et al. 96-66 3,253,915 5/1966 Weyerts et a1. 9666 J. TRAVIS BROWN, Primary Examiner E. C. KIMLIN, Assistant Examiner U.S. Cl. X.R. 9666,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. I 3, 713, 827

DATED January 30, 1973 INVENTOR(S) I Jozef Frans WILLEMS It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 30, "position" should read positions Column 2, lines 55 57, formula 2 should appear as follows:

Column 3, lines 20 29, formula 6 should appear as follows:

Column 10, line 67, "Germany" should read W. -Germany Column 12, lines 4 and 5, claim 1, "subsituated" should read substituted Column 12, line 8, delete "the"; Column 12, line 32, claim 2, before "derivatives" insert hydroquinone Signed and Sealed this sixteenth Day of March 1976 [SEAL] RUTH C. MRSON C. MARSHALL DANN Attesnng Officer Commissioner oj'Patents and Trademarks