CA1313082C - Silver halide photographic developer compositions and process for the formation of photographic silver images - Google Patents

Abstract

Photographic Silver Halide Developer Compositions and Process For Forming Photographic Silver Images ABSTRACT OF THE DISCLOSURE
An aqueous alkaline photographic silver halide developer composition comprising a dihydroxy benzene developing agent, an auxiliary superadditive developing agent, an antifogging agent, an antioxidant and a buffering agent, characterized by the fact that the composition further comprises a stabilizing amount of an .alpha.-ketocarboxylic acid. The developer composition has a better resistance against air oxidation and can be left in continuous transport automatic processors for several days without undergoing any substantial decrease of its developing properties. The developer composition is particularly useful in a process for the formation of a high contrast silver image by developing silver halide photographic elements including at least a negative acting surface latent image type silver halide emulsion in the presence of a hydrazine compound, preferably in the additional presence of an effective amount of a contrast promoting agent.

Description

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Photos~ra~ Silver l~alide DeveloPer ComPositions and Process For Forming Photogra~hic Silver Images FIELD OF THE INVENTION

The present invention relates to pho~ographic silver halide developer compositions, particularly to photograph-ic silver halide developer compositions having an improved resistance to air oxidation, and to a process for forming a silver image by developing a silver halide photographic element, particularly to a process for forming a high-contxast negative silver image.

BACKGROUND OF THE ART

In general, the processing of ~lack and white silver halide photographic materials is performed in the order of development, stopping, fixing and washing.
Development is ordinarily carried out with aqueous alkaline developer compositions con~aining a developing a~ent, usually o~ the dihydroxyben~ene type such as hydro-quinone. The activity of these de~loping agents i~ ~x~at-ly influenced by the pH of the s~lution and the optimum pH
range should ~ot significantly change during the useful life of the developer composition; therefore ~he composi-tion has always to possess a high buffering capacity. The developer compositions are usually provided with antifog-ging agents (in particular inorganic antifogging agents such as soluble bromides and organic antifogging agen~s~
to retard the development of non-exposed silver halide grains and decrease ~og, i.e. silver formed as a result o~
the d~velopman~ o~ said larains.
Antioxidant compounds are usually added to the alka-line devel~per composi~ion to limit oxida~ion of the de-veloping agents by air. Alkaline and ammonîum sulfi~es are the most common compounds used for this purpose, but other ~k , .

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- 2 ~ 3~2 60557-3272 antio~idant co~pounds such as hydroxylamine and ascorbic acid can be used instead of or in combination with such sulfites.
It is a well-known phenomenon that traces of certain metal ions, such as copper and iron ions, have a catalytic effect on the aerial oxidation of the developing agents (the metal ions may have been introduced as impurities in the water or in the chemicals used to compound the developer composition). The cata-lytic effect of said ions on. the aerial oxidation of developing agents can be reduced by suitable se~uestering agents. Sequester-ing agents work by forming fairly stable and saluble complexes with the metallic ions so that free metal ions are present only in small amounts.
However, the activity of antioxidant compounds and sequestering agents to improve the resistance to aerial oxidation is much reduced when silver halide photographic materials are treated in continuous transport processing machines, especially at high temperatures~ In this case, considerably high quantities of air are introduced into the developer composition used in processing machines, said aeration causing a rapid degradation of the de~eloper itself.
The problem of resistan.ce to aerial oxidation is par-ticularly serious in developing compositions intended for pro-cesses of ~igh contrast silver image formation in the presence of hydrazine compounds (as described for instance in United States patents 4,168,977; 4,224,401; 4,269,929; 4,272,614 and 4,323,643), wherein the relative high pH levels in developi~g ~, :' Q~32 - 2a - 60~57-3272 compositions reduce their effective life.
SUMM~RY OF THE INVENTION
Aqueous alkaline photographic silver halide developer compositions, which can be left in continuous transport pro-cessing machines for several days without any ' .....

. . .. :

3~3Z
~ 3 ~ ~ b~z~

..significant degradation, comprising a r~n~ene~de-veloping agent, an auxiliary superadditive developing agent, an antifogging agent, an antioxidant and a buffer-ing agent, are characterized by the fac~ that ~he composi-tions further comprise a stabilizing amount of an a-~eto-carboxylic acid.
Said developer compositions are particularly suitable in a process for forming a high contrast silver image by developing silver halide photographic elements, including at least a negative acting surface latent image-type sil-ver halide emulsion layer, in the presence of a hydrazine compound, preferably in the additional presence of an ef-fective amount of a contrast promoting agent.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an a~ueous alkaline photographic silver halide developer composition compris-ing a dihydroxybenzene developing agent, an auxiliary superadditive developing agent, an antifogging agent, an antioxidant compound and a buffering agent, characterized by further comprising a stabilizing amount of an a-keto-aarboxylic acid compound.
~ . ., Particularly, according to the present invention the a-ketocarboxylic acid compound corresponds to formula (I):
R-CO COOH (I) wherein R represents a hydrogen atom or an organic yroup.
Organic groups useful in the above formula are well ~nown in the photo~raphic art and can be selected upon the basis o~ ~arious common criteria. For example, they should be reasonable in size and nature, useful to the properties of the a-~et~carboxylic aci~ compounds such as to control th~ir solubility in the photographic developer composition and to obtain the desired stabilizing effects with no siq-nificant deleterious e~ects on the photographic charac-teristi~s of the silver image, such as fog~ sensitivity and contrast. In the compounds represented by the formula .... : . "~.. . . ...

13~3~2 (I~ above, R particularly represents a CooH group Gr a substitute~ or unsubstituted aliphatic group, a su~sti-tuted or unsubstituted aromatic group or a substituted or unsubstituted heterocyclic group, each of these R groups preferably having a number of carbon atoms not higher than 12. The aliphatic groups include straight and branched chain alkyl groups, cycloalkyl groups, alkenyl groups and alkynyl group~. Said straight or branched chain aliphatic groups Icomprising alkyl, alkenyl and alkynyl groups) preferably contain 1 to 8 carbon atoms (e.g., methyl, eth-yl, propyl, allyl, butyl, amyl, hexyl, octyl), and more preferably contain 1 to 4 carbon atoms. The cycloalkyl groups preferably contain 3 to 10 carbon atoms; preferred examples thereof include cyclopropyl, cyclopentyl, cyclo-hexyl and adamantyl groups. ~he substituted or unsubs~i-tuted aromatic groups preferably contain 6 to 10 ring car-bon atoms (e.g., phenyl, naphthyl). Useful substituents of said aliphatic and aromatic groups include halogen, aryl~
cyano, carboxy, alkylcarbonyl, arylcarbonyl, alkoxy, alkoxycaxbonyl, aryloxycarbonyl, alkylaryloxycarbonyl, sulfoxy, alkylsulfonyl, arylsulfonyl, and the like. Typi-cal examples of a-ketocarboxylic acid compounds according to the present invention include HOC-COOH (glyoxylic ac-id), HOOC-CO-COOH ~mesoxalic acid), CH3-CO-COOH tpyruvic acid), E~OOC-CO-CH2-CO-COO~ ~oxalacetic acid), C2H~-CO-COOt~
( 2-ketobutyric acid), HOOC-CH2-CH2-CO-COOH ( 2-ketoglutaric acid), C6HS-CH2-CO-COOH (phenylpyruvic acid) and CH3 ~ CH-CO-COOH (a-keto-~-methylvaleric acid).
C2H5 ~/
a Ketocarboxylic acid compounds may be adavantageously obtained by oxidation under mild conditions of a-hydroxy acids or methyl ketones. These and other methods to obtain a-keto~arboxyllc acid compound~ are described, ~or exam-ple, by V. Migrdichian, Organic Synthesis, Reinhold Publ., 1956, page 267.
The dih~droxybenzene developing agents employed in the aqueous alkaline developing solutions of this .
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invention are well-known and widely used in photographic processing. The preferred developing agent is hydroqui-none. Other useful dihydroxybenzene developing agents in-clude chlorohydroquinone, bromohydroquinone, isopropyl-hydroquinone, tolylhydroquinone, methylhydroquinone, 2,3-dichlorohydroguinone, 2,5-dimethylhydroquinone, 2,3-dibromohydroquinone, 1,4-dihydroxy-2-acetophenone-2,5-di-methylhydroquinone, 2,5-diethylhydroquinone, 2,5-di-p-phenethylhydroquinone, 2,5-dibenzoylaminohydroquinone, 2,5-diacetamidohydroquinone, and the like.
Such developing agents can be used alone or, prefera-bly, in combination wi~h an auxiliary developing agent or agents which show a superadditive developing effect, such as p-aminophenol and substituted p-aminophenols (e.g. N-methyl-p-aminophenol or metol and 2,4-diaminophenol) and 3-pyrazolidones (e.g. 1-phenyl-3 pyrazolidone or pheni-done) and substituted pyrazolidones (e.g. 4-methyl-1-phen-yl-3-pyrazolidone and 4,4'-dimethyl-1-phenyl-pyrazoli-done).
The aqueous alkaline developing compositions of this invention contain an antioxidant compound in a guantity sufficient to give good stability charact~ristics. Useful antioxidant compounds include the sulfite preservatives, i.e. any sulfur compound capable of forming sulfite ions in aqueous solutions, such as alkali metal or ammonium sulfites, bisulfites, me~abisulfites, sulfurous acid and carbonyl-bisulfite adducts. Typical examples of sulfite preservatives include sodium sulfite, potassium sulfite, lithium sulfite, ammoni~n sulfite, sodium bisulfite, po-tassiwm metabisulfite, bisulfite-formaldehyde addition compound sodium salt, and the like. Also ascorbic acid is a known preservative against aerial oxidation of the de-veloper for use in the developing composition of ~he pre-sent invention.
The antifoggant agents, known in the art to eliminate fog on the developed photographic silver halide films, useful in the developer compositions of this invention - 6 _ 13~3~8~ 60557-3272 include organic antifoggant agents, such as derivatives of benz-imidazole, benzotriazole, tetrazole, imidazole, indazole, thiazole, etc., used alone or ln combination. The organic anti~oggants are well known as discussed, ~or example, in Mees, The Theory of the Photographic Process, 3rd Edition~ 1966, p. 344-346. Derivatives of ~enzimidazole and benzotriazole are pre~erred in the practice of this invention, as described in United Statas patent 4,6Q3,956.
Said deri~atives include lower alkyl groups (having 1 to 4 carbon atoms) or halogen (chlorine) substituted benzimidazole and benzo-triazole antifoggant agents.
At least an inorganic alkali agent is used in the developer compositions of this invention to achieve the preferred pH range which normally is above 10. The inorganic alkali agent group includes KOH, NaOH, potassium and sodium carbonate, etc.
Other adjuvants well known in the art are comprised in the developer compositions of this invention. These include in-organic antifogging agents such as soluble halides (e.g. KBr and NaBr), buffering agents (e.g. borates, carbonates and phosphates) and sequestering agents such as aminopolycarboxylic acid compounds (e.g. nitrilotriacetic acid or NTA, ethylenediaminotetracetic acid or EDTA, diethylenetriaminopentacetic acid or DTPA, diamino-propanoltetracetic acid or DPTA and ethylendiamino-N,N,N',N'-tetrapropionic acid or EDTP), ~-hydroxycarboxylic acid compounds (e.g. lactic acid), dicarboxylic acid compounds (e.g. oxalic acid and malonic acid) or polyphosphate compounds (e.g. sodium hexa-mataphosphate).

- - 6a - 1 3~ ~ 08Z 60557-3272 The aqueous alkaline developing compositions of this lnvention can vary widely with respect to the concentration of the various ingredients included therein. Typically, the dihydroxy-benzene developing agent i9 used in an amount of from about 0.040 to about 0.70 moles per liter, preferably in an amount of from about 0.08 to about 0.40 moles per liter; the auxiliary developing agent is used in an amount of from about 0.0001 to ; about 0.15 moles per .'~

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liter, preferably in an amount of ~rom about 0.0005 to about 0,01 moles per liter; the inorganic antifogging a~ent is used in an amount of from about 0.001 to about 0.2 moles per liter, preferably in an amount of from a~out 0.01 to about 0.05 moles per liter ; the antioxidant com-pound ~such as the sulfite preservative) is used in an amount of from about 0.001 to about 1 moles per liter, preferably in an amount of from about 0.08 ~o about 0.7 moles per liter of solution; the organic antifogging com-pound is used in an amount of from about lxlO 5 to about 5xlO 2 moles per liter, prefera~ly in an amount of from about 5xlO 4 to about lxlO 2 moles per liter; the buffer-ing agent is used in an amount of from about 0.02 to about 1 moles per liter, preferably is used in an amount of from about 0.07 to about 0.5 moles per liter and the sequester-ing agent is used in an amount of from about lxlO 4 to about 0.2 moles per liter, preferably in an ~mount of irom about 5xlO 3 to about 3xlO 2 moles per liter.
According to the present invention, the black and white developer composi~ion comprising the above reported ingredients has a better resistance to air oxidation if including an a-ketocarboxylic acid in a stabilizing quan-tity. The developer composition according to the present invention can be lef t in continuous transport automatic processors for several day~, such as for instance for two days, without being replaced with fresh developer solu-tions or continuously replenished with a replenisher com-position still maintaining substantially unchanged its development capability. The effective stabilizing quantity o~ the a-ketocarhoxylic acid preferably ranges from about 5xlO 5 to about 3xlO 1 moles per liter, more preferably from about 0.01 to about 0.08 moles per liter.
Of courser ~he stabiliæing effect of the compounds of the present invention depend upon their chemical nature, upon the ~uantity w.ith which they are used and upon the chemical nature of ~he developer composition the stability of which has been improved by adding the compounds of the present invention. The man skilled in the art can choose the most sui~able compounds to be used and the quantities thereof according to his operational needs and the stabi-lization demands.
The man skilled in the art can also evaluate the sta-bilization improv~ments, thus obtained, ~o be more or less significant according to particular circumstances he has found.
To the purposes of the present invention it is deemed to be significant to evaluate the stability of the devel-oping bath as absorbance variation (measured at S00 nm) when a sample of 100 m~ developer solution is stored under room conditions in a 1000 ml open flask in contact with air for significant times, for instance of one, two or three days (from a practical point of view two days and, still better, three days are a particularly significant time since they represent a week-end work stop).
Making reference to a three~day period of time, the stability of a developing bath can be said to be si~nifi-cantly improved according to the present invention when the absorbance, measured under the above specified condi-tions with a LAMB~A 5 spectrophotometer of Perkin Elmer, is brought to a value not higher than 1, pr~ferably not higher than 0.8 by adding a-ketocarboxylic acidO
Of course, both the p~ of the solution and the stor-ing temperature will affect the obtained results. The higher the values of such variables, the higher in general the measured absorbance values.
Alternatively and, preferably, additionally, a bath can be considered to be stable when its pH is stable. To the purposes of the present inven~ion, a developing bath can be considered to be unstable when after three days under the above reported condltlons its p~ varies of an absolute value, which is the 5um of all changes of at least 0.025, higher than 0.2 unit, while it can be consid-ered to be stable when pH varies of an absolute value low-er or equal to 0.2 units. The term "absolute value`' ~3~

g obviously means that the total variation and the single variations it consists of are counted undependently from their sign: a first variation from 0 to -0.2 and a further variation fro~ -0.2 to +0.2, for instance, herein mean a total variation in absolute value of 0.6.
The photographic developer compositions of the present invention, having improved resistance to air oxi-dation, are useful for ~orming black and white silver images by development o~ light-sensitive silver halide photographic elements, more specifically for forming high contrast silver images by development of lithographic films used in the field of graphic arts. ---In particular, said developer compositions are usefulfor forming high contrast silver images by development of a photographic element, including a negative acting sur-face latent image-type silver halide emulsion layer, in the presence o a hydrazine compound, preferably in the additional presence of a contrast promoting agent.
Accordingly, in one particular aspect the present invention relates to a process for forming a high contrast negative photographic image by development of a silver halide photographic element, including at least a negative acting sur~ace latent image-type silver halide emulsion layex, in the presence of a hydrazine compound and prefer-a~ly in the additional presence of a contrast promoting agent, ~1 th the aqueous alkaline developer composition comprising a dih~droxybenzene developing agent, an a~xil-iary superadditive developing agent, an antifogging agent, an antioxidant compound, a buffPring agent, and a stabi-lizing amount o~ an a-ketocar~oxylic acid compound, as descrlbed above.
The silver halide emulsions for use in the process of the present invention may be silver chloride, silver chloro-bromide, silver ~odo-bromide, silver iodo-chloro-bromide or any mixture thereof. Generally, the iodide con-tent of the silver h~lide emulsions is less than about 10%
iodide moles, said content ~eing based on the total silver 13~3~

halide. The silver halide emulsions are usually monodispersed or narrow grain size distribution emulsions, as described for example in United States Patent Specifica~ions 4,166,742; 4,1~8,977;

4,224,401; 4,237,214; 4,241,164; 4,272,614 and 4,311,871. The silver halide emulsions may comprise a mixture of emulsions having different grain combinations, for example a combination of an emulsion having a mean grain size below 0.4 ~ with an emulsion having a mean grain size above 0.7 ~ or a combination of two emulsions, both having a grain size below 0.4 ~, such as for e~ample a first silver halide emulsion having a mean grain size of 0.1 to 0.4~ and a second silver halide emulsion with particles having a mean grain volume lower than one half the particles of the first emulsion.
The silyer halide grains of the emulsions for use in the process of the present invention are capable of forming a surface latent image, as opposed to those emulsions forming an internal latent image. Surface latent image-forming silver halide grains are most employed in negative type silver halide emulsions, while internal latent image-forming sil~er halide grains, though capable of forming a negative imagP when developed in an internal developer, are usually employed with surface developers to form direct-positive images. The distinction ~etween surface latent image and internal latent image-forming silver halide grains is well-known in the art. Generally, some additional ingredients or steps are required in the preparation of silver halide grains capable of preferentially forming an internal latent image instead - lOa ~ ~3 1~ O~ 60557-3272 of a surface latent image.
In the silver halide emulsions for use in the process of the present invention, the precipitation or the growth of the silver halide grains may be carried out .in the presence of metal salts or complex salts thereof, such as rhodium and iridium salts or complex salts thereof. According to the present inven-tion, the presence of rhodium 1~

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-, or iridium has been found anyhow not to be necessary to obtain the high contrasts. Silver halide grains free of rhodium or iridium, as well as those formed or ripened in the presence of rhodium and iridium may be used.
The silver halide emulsions of the process of the present invention may be not chemically sensitized, but are preferably chemically sensitized. As chemical sensiti-zation methods for silver halide emulsions, the known sul-fur sensitization employing su~ur compounds, the reduc-tion sensitiæation employing mild reducinq agents and the noble metal sensitization can be used, either alone or in combination.
The silver halide emulsions can be spectrally sensi-tized with dyes from a variety o classes, including the polymethine dye class, ~uch as cyanines, merocyanines, complex cyanines and merocyanines (i.e., tri , tetra- and poly-nuclear cyanines and merocyanines), oxonols, hemi-oxonols, styryls, merostyryls and streptocyanines.
The binder or protective colloid for the silver halide layer and layers of the photographic element is preferably gelatin, but other hydrophilic colloids or syn-thetic wa~er insoluble polymers in the form of latexes can be used for partially or completely replacing gelatin~
In addition, the photographic elements may also con-tain any photographic additive known in the art, such as for example s~abilizers, antifoggants, hardeners, plasti-cizers, development accelerators, gelatin extenders, mat-ting agents and the like.
To achieve the ~enefits of this invention, a hydra-zine compound has to be present during development of the exposed element.
The hydra~ine compound can be incorporated in the photographic element or in the developing solution or both-in the developing solution and in the photographic ele-m~nt.
Hydra~ine and any water soluble hydrazine derivative are e~fective to increase contrast when incorporated in 3~

the developing composition. Preferred hydrazine deriva-tives ~o be used in the developing solution of this inven-tion include compounds of ormula ~V):
R6~ / R7 N-N (V) wherein R6 is an organic radical and R7, R8 and Rg each are hydrogen or an organic radical. Organic radicals rep-resented ~y R6, R7, R~ and ~9 include hydrocarbon groups, such as an alkyl group, an aryl group, an aralkyl group and an alicyclic group and such groups can be substi~uted with substituents such as alkoxy groups, carboxy groups,-sulfonamido groups and halogen atoms.
Other examples of hydra~ine derivatives, which can be incorporated in the developing solutions, are hydrazides, acyl hydrazines, semicarbazides, carbohydrazides and aminobiuret campounds.
Specifical examples of hydrazine derivatives, which can be incorporated in the developing solutions of the present invention, are disclosed in US Patent Specifica-tion 2 j 419,575.
Preferably, the h~drazine compound is incorpora~ed--in-the photographic element, for example in a silver halide~
emulsion layer or in a hydrophilic colloidal layer, pref-erably a hydrophilic colloidal layer adjacent to the emul-sion layer in which the effects of the hydrazine compound are desired. It can, of course, be present in the photo-graphic element dis~ributed between the emulsion and the hydrophilic colloidal layers, such as ~ subbing layers, interlayers and protective layers.
H~drazine compounds suitable to be incorporated into the pho~ographic element are disclosed in GB Paten~ Speci-fication 598,108 and in U5 Patent Specification 2,419,974;
they include the water soluble alkyl, aryl and hetero-cyclic hydrazine compounds, a well as the hydrazide, semicarbazide and aminobiuret compounds.
Particularly preferred hydrazine compounds, for use 13~3~B~

according to this inven~ion incorporated in the photo-graphic element, are the formylhydrazine compounds corre-sponding to the formula:
R1o NHNH-C-~ (VI) wherein R1o represents a substituted or unsubstituted aro-matic group. Examples of aromatic groups represented by R1o include a phenyl group and a naphthyl group. Such aro-matic groups may be su~stituted with one or more substi-tuents which are not electron at~racting, such as straight or branched-chain alkyl groups ~e.g. methyl, ethyl, prop-yl, isopropyl, n-butyl, iso~utyl, n-ottyl, n-hexyl, tert.-octyl, n-decyl, n-dodecyl, etc.), aralkyl groups te.g. benzyl, phenethyl, etc.), alkoxy groups (e.g. meth-oxy, ethoxy, 2-methyl-propyloxy, etc.3, amino groups which are mono- or disubstituted with alkyl groups, acylamino-aliphatic groups (e.g. acetylamino, benzoylamino, etc.), etc., as disclosed in US Patent Specification 4,168,977 and in CA Patent Specification 1,146,001. Such aromatic groups may also be substituted with a ureido group of for-mula:
o Rll-N-C-N-wherein Rll and R12 (which may b~ the same or different) each represents hydrogen, an aliphatic group (such as a straight or branched-chain alkyl group, a cycloalkyl group, a substituted cycloalkyl group, an alkenyl group and an alkynyl group), an aromatic group (such as a phenyl group and a naphthyl group) or a heterocyclic group; R8 represents hydrogen or an aliphatic group (such as those listed above) as descrlbed in US Patent Specification 4,323,64~.
Other hydrazine compounds, for use incorporated in the photographic element, are those represented by the formula:

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R14-NHNH ~ R15 (VII) wherein R14 represents the same aromatic group of the the formula above and R15 represents an alkyl group having 1 to 3 carbon atoms, which may be a straight or branched-chain alkyl (e.g. methyl~ ethyl, n-propyl a~d isopropyl) or a phenyl group. The phenyl group may be substituted wi~h one or more substituents which preferably are elec-tron attracting groups, such as halogen atoms (chlorine, bromine, etc.)/ a cyano group, a trifluoromethyl group, a carboxy group or a sulfo group, etc. Specific examples of hydrazine compounds represented by the formula above are disclosed in US Paten~ Specification 4,224,401.
Still o~her examples of hydrazine compounds, for use according to this invention incorporated in the photo-graphic element, are those corresponding to the formula (VIII):
"Z ~
=N(y)mx-NHNH-ll R17 (VIII) "N O

wherein R16 represents hydrogen, an aliphatic group which may be substituted; Y represents a divalent lin~ing group;
m represents 0 or 1; X represents a divalent aromatic group (such as for example a phenylene group, a naphthyl-ene group and the ana~ogous substituted groups thereof);
R17 represents a hydrogen atom, an aliphatic group which may be substituted and Z represents a non metallic atom groups necessary to form a S- or a 6-membered heterocyclic ring. Speific examples of hydrazine compounds represented by the formula above are disclosed in US Patent Specifica-tion 4,272,614.
In one part~cular ~referred form, the hydrazlne com-pound to be incorpora~ed in the photographic element is substituted with ballasti~g groups, such as the ~allasting groups of incorporated colar couplers and other non-dif-fusing photographic emulsion addenda. Said ballasting groups contain at least 8 carbon atoms and can be selected from the relatively non reactive aliphatic and aromatic groups, such as alkyl, alkoxy, alkylphenyl, phenoxy, alkylphenoxy groups and the like.
Such hydrazine compounds can be incorporated in the photographic element usin~ various methods well-known in the photo~raphic art, the most common being the method o~
dissolving the hydrazi~e derivatives in a high boiling crystalloidal solvent and dispersing the mixture in the emulsion, as described for example in US Patent Specifica-tion 2,322,027.
Hydrazi~e compounds incorporated in the developing solutions in the practice of this invention are effective at very low levels of concentration. For example, hydrazine compounds give useful results in the developing solution in a quantity of about 0.001 moles per liter to about 0.1 moles per liter~ more preferably in a quantity from about 0.002 to about 0.01 moles per liter. Hydrazine compounds incorporated in the photographic element are typically employed in a concentration ranging from about 5xlO 4 to about 5xlO 1 moles per mole of silver, more preferably in a quantity from about 8xlO 4 ~o about 5xlO 2 moles per mole of silver.
Preferably, according to the process of the present invention, a contrast promoting agent is additionally present during development in the presence of the hydra-zine compound. The use of a contrast promoting agent al-lows a high contrast to be obtained by developing the pho-tographic el~ment in the presence of the hydrazine com-pound, at a pH lower than the pH necessary to obtain the high contrast when the hydrazine compound alone is used.
As a consequence of a lower pH level, the effective life of the developer composition is further enhanced.
The contrast promoting agent has to be present during development of the exposed photographic element. The con-trast promoting agent may be incorpora~ed in the photo-graphic element or in the developer composition or both in :

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the photographic element and in the developer composition.
The contrast promoting agents comhined with the hydrazine compounds produce a very high contrast, which means a contrast of at least 10. This contrast is the slope of the straight line portion of the characteristic curve (referred to as "average contrast") and is measured between two points located at densities of 0~10 and 2.50 above Dmin.
A preferred class of contrast promoting agents are the alkanolamine compounds which comprise amine compounds wherein the ni~rogen atom is directly attached to a hydroxyalkyl group. Particularly preferred alkanolamine compounds, for use as contrast promoting agents, are the compounds of formula (IX):

R 8-N (IX) wherein R18 represents an hydroxyalkyl group of 2 to lO
carbon atoms and R19 and R20 each represent a hydrogen atom, an al~yl group of 1 to 10 carbon atoms, a hydroxy-alkyl group of 2 to 10 carbon atoms, a benzyl group, or a CnH2n N~

group wherein n is an integer of 1 to 10 and R21 and R22 each repres~nt a hydrogen atom, an alky~ group of 1 to 10 carbon atoms, or a hydroxyalkyl group of 2 to 10 carbon atoms.
Typical specific examples of the numerous alkanol-amine compounds that can be used those described in the US
Patent Specification No. 4,269,929.
Preferably, the alkapolamine compounds are incorpo-rated in the aqueous alkaline developer composition in a contrast promoting amount. The alkanolamine compounds dif-fer markedly in their degree of effectiveness as contrast promoting agents. The less effective alkanolamine com-pounds may be used at a relatively high concentration to 3~

obtain high contrast at lower pH, such as a pH lower than 12.
Typically, the alkanolamine compounds are used in an amount of about 0.009 to about 0.85 ~oles per liter, preferably in an amount of about 0.09 to about 0.35 moles per liter of developing solution.
A still more preferred class of contrast promoting agents are arylalkyl alcohols, preferably, the compounds contain-ing a hydroxymethylidine group. Particularly preferred hydroxy-methylidine group containing compo~ds, for use as contrast promoting agents, are the compounds of formula (II~:

l\
~ CHOH (II) wherein Rl and R2 each independently represent a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, or R
and R2 together complete a non aromatic cyclic group.
The aliphatic groups represented by each of Rl and R2 include a straight or branched chain alkyl group, a cycloalkyl group, an alkeny,l group, an alkynyl group. Examples of straight or branched chain alkyl groups are alkyl groups having 1 to 10, and preferably 1 to 5 carbon atoms, such as a methyl group, an ethyl group, a propyl group, a butyl group. The cycloalkyl group has generally 3 to 10 carbon atoms. Preferred examples thereof are a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group.
Examples of aromatic groups shown by each of Rl and R2 includ~ a phenyl group and a naphthyl group.

- 17a - ~3~3~8~ 60557-3272 The heterocyclic ring group shown by each of Rl and R2 is a 5-membered or 6-membered single or condensed ring, having at least one oxygen, nitrogen, sulfur or selenium atom with or without substituents. Preferred examples o~ heterocyclic groups include a pyrroline ring, a pyridine ring/ a quinoline ring, an indole ring, an oxazole ring, a , ,. :

~3~

benzoxazole ring, a naph~hoxazo1e ring, an imidazole ring, a benzimidazole ring, a thiazoline ring, a thiazole ring, a benzothiazole rin~, a naphthothiazole ring, a selenazole ring, a benzoselenazole ring, a naphthoselenazole ring, etc.
of course, as known in the art, such described Rl and R2 substituents may be substituted with any substituents known in the art not to negatively affect the development process. Examples of such substituents could be alkyl, alkoxy and hydroxy substituents.
When the hydroxymethylidine group containing compunds are incorporated in the aqueous alkaline developer compo-sition, a parameter to take into proper account is their water solubility. In order not to have them water-inso-luble, it is preferred to keep the total number of carbon atoms in Rl and R2 to a value of less than 20 carbon at-oms, preferably less than 15 carbon a~oms.
Speci~ic examples of hydroxymethylidine group con-taining compounds that can be used in the process of the present invention include the following compounds:
1) methyl alcohol 2) ethyl alcohol 3) 1 propanol 43 2-propanol 5) l-butanol 6) 2-methyl-1-pxopanol 7) 3-methyl~ utanol 8) 2-propen-1-ol 9) benzyl alcohol 10) salicyl alcohol 11) p~methoxy-benzyl alcohol 12) ~-phenethyl alcohol 13) l-phenyl~ethan-l-ol ~phenyl-methyl carbinol) 14) diphenylmethanol (ben~ydrol) 153 3-phenyl-l-prope~ ol ~cin~amyl alcohol) 16) 4-diphenylmethanol 17) 1-phenyl-1,2-ethanediol (styrene glycol3 -: .
,: i : ' :. :

~ 363~3~

18) tetrahydrofurfuryl alcohol 19) 1,2-ethanediol 20) 1,2-propanediol 21) 1,3-propanediol 22) 1,2-butanediol 23) 1,3-butanediol 24) 1,4-butanediol 25) 1,5-pentanediol 26) 1,6-hexanediol 27) pinacol 28) 2-butene-1,4-diol 29) 1,2-cyclohexanediol 30) 1,4-cyclohexanediol 31) 1,2,4-butanetriol 32) phenylethylcarbinol 33) phenylcyclopropylcarbinol 34) cycloheptanol 35) 1,2,3,4-tetrahydro-1-naphthol (a-tetralol).
T~pically, the hydroxymethylidine group containing compounds, when incorporated in the developer composition, are used in an amount of about 0.001 to about 3.00 moles per liter, preferably in an amount of about 0.01 to a~out 1.50 moles per liter. When used in reactive associa ion with the negative acting surface latent image-type silver halide grains incorporated in the silver halide element, the hydroxymethylidine group containing compounds are preferably diarylcarbino~ compounds.
More preferably said diarylcarbinol compounds corre-spond to the formula (III) or (IV):
R3R4R5COH ( III ) R3R4R~jC(CH2)mOH ~IV?
wherein R3 and R4 represen~ a substituted or unsubstituted aromatic group, R5 represents a hydrogen atom~ a substi-tuted or unsubstituted alkyl group or a substituited or unsubstituted aromatic group and m represents a positive integer from 0 to 4.
The diarylcarbinol compounds can be present during ~3~

development of the exposed element and the element can contain the diarylcarbinol compound prior to the contact with the whole developer composition. By "contact with the whole developer composition" is meant that the exposed element is placed into conctact with all of the required developer ingredients.
Accordingly, the diarylcarbinol compounds can be in-corporated into the photographic element. For example they may be incorporated in the silver halide emulsion layer of the element or in a hydrophilic colloid layer adjacent to the silver halide emulsion layer in which the effects of the diarylcarbinol compounds are desired. They can, for instance, be present in the photographic element distrib-uted between the emulsion la~er(s) and the hydrophilic colloid layers, such as for instance a subbing layer, interlayers and protective layers.
The aromatic groups represented by R3, R4 and R5 of formulas (III) and (IV) above include a naphthyl group and, preferably, a phenyl group. The alkyl groups repre-sented by R5 of formulas (III) and (IV) above include branched or straight chain alkyl groups, preferably low alkyl groups ~having 1 to 5 carbon atoms). Such groups may contain substituents, such substituents being chosen in nature and size as not to negatively affect their behaviour according to the present invention. For what concerns their nature, such substituents include for exam-ple an alkyl group, an alkoxy group, a cyano group, a di-alkylamino group, an alkoxycarbonyl group, a carboxy group, a nitro group, an al~ylthio ~roup, a hydroxy ~roup, a sulphoxy group, a carbamoyl group, a sulfamoyl group, a halogen group, etc. Wi~h regard to their size, such sub-stituents are preferred to have 1 to 10 carbon atoms, more pre~erably 1 to 5 carbon atoms.
Parametrs to take into proper consideration are solu-bility and boiling point of the diarylcarbinol compounds for use in the process of the present invention. In fact said compounds are to be substantially water soluble or , - 21 ~

soluble in water miscible solvents (by "substantially wa-ter soluble" it is meant soluble in water in a quantity of at least 1% by weight and by "soluble" in water miscible solvents it is meant that they are to be soluble in water miscible solvents in a ~uantity of at least 5% by weight) in order to introduce them into the aqueous coating compositions used to form the layers of the photographic elements according to ~he present invention. Sa.id diarylcarbinol compounds are re~uired to have a suffi-ciently high ~oiling point not to evaporate during drying of the layer forming coating composition. Said boiling points are pref~rably higher ~han 150C, more preferably higher than 200C.
Specific examples of diarylcarbinol compounds include the following compounds:
l) diphenylmethanol (benzydrol) 2) 4,4'-dimethoxydiphenylmethanol 3) 4,4'-dimethyldiphenylmethanol 4) 2,2'-dibromodiphenylmethanol 5) 4,4'-di~romodiphenylmethanol 6) 2,2'-dinitrodiphenylmethanol 7~ 4,4'-dinitrodiphenylmethanol : 8) 2,3'-dimethoxydiphenylmethanol .
9) 2,4'-dihydroxydiphenylmethanol lO) 4-ethyldiphenylmethanol ll) 4-methyldiphenylmethanol 12) 2,2',4,4'-te~ramethyldiphenylmethanol.
The diarylcarbinol compounds are used incorporated into the photographic silver halide element in amount form about lO 4 to about 13 l moles per mole of silver, moxe preferably ln an amount from about lO 3 to about 5xlO 2 moles per mole of silver.
The followin~ examples, which further illustrate the invention, repor~ some experimental d~ta in order to show the stability to aerial oxidation of the developer compo-sitions of the present invention. In particular, the ab-sorbance at 500 nm of lO0 ml of developer solution stored 3~

in a 1,000 ml conical flask in contact with air and the variation of the pH between fresh and stored developer solution (~ pH) were measured. It i5 in fact well known that aerial oxidation of alkaline developers containing hydroquinone results in the liberation of alkali (and therefore a pH increase) and in the darkening of the solu-tion.

EXAMPL~ 1 Three silver halide photographic developer solutions (I to III) were prepared according to the following table 1:

Table 1 I II III
____________~________ __________________________ W~ter ml 600 600 600 KOH 35% g 210 250 257 1-phenyl-4,4-dimethyl--3-pyrazolidone g 0.4 0.4 0.4 sec-phenethyl alcohol g 1.5 2.5 2.5 5-methyl~enzotriazole g 0.1 0.1 0.1 DTPA.SNa 40% g 5 - -EDTA g - 3 5 Ketomalonic acid H2O g ~ 2 Pyruvic acid g - - 5 KBr g 3 3 3 KCl g 2 2 2 H3PO4 86% g 38 45 45 K2S3 44% g 200 200 200 H~droquinone g 30 30 30 Watex to make 1 liter pH at 2CC 11.5 11.5 11.5 The values of the absorbance at 500 nm for the ; .

. .

~L3~
- 23 ~

developer solutions stored for different days are reported hereinbelow in Table 2.

Table 2 : Developer Absorbance values solutions 1 day 2 days 3 days ____________~________________________________________ ___ I 0.20 0.50 1.60 II 0.10 0.40 0.70 III 0.10 0.30 0.60 Two silver halide photographic developer solutions (IV and V) were prepared according to the following table 3:

Table 3 ...
IV V
_______________________,_________________________________ .
Water ml 800 800 KOH 35% g 72 72 X2S25 g 35 35 K2CO3 g 9.8 ~.8 DPTA.5Na 40% g S
EDTA g ~ 3 Diethanolamine g 15.6 15.6 L~ctic acid 8Q% g 8 Pyruvic acid g ~ 5 KBr ~ 3-3 3-3 Hydro~uinone g 16 16 1-Phenyl-3-pyrazolidone g 0.24 0.24 1-Phenyl-5-mercapto--t~trazole g 0.028 0.028 ~enzotriazole g 0.65 0.65 : .... ,, .,,~ . .... . .

~3~3~
~ 24 -Water to make 1 liter pH at 20C 10.49 10.46 The~pH and the absorbance values at 500 nm of the stored developer solutions are reported hereinbelow in table 4.

Tàble 4 Developer ~ pH Absorbance values solutions 1 day 2 days 1 day 2 days 3 days ______________________________________________._______ __ IV +0.6 ~0.7 0.2 2.0 3.0 V +0.05 +0.1 0.1 0.2 0.6 Six silver halide photographic developer solutions ( VI to XI ) were prepared according to the f ollowing table - 25- ~3~ 2 o ~ I O ao o o o o o o I Lfl ~ ~1 X I ~D ~ ~ ~ O O ~ ` `
r~ ~ ~ o o I

o In XIo~ oooooo~DI~ ~1 ~r Ln ~ o o ~ ~ o o o X,o, oooooo,,~ ,, H I ~CI ~Lt`l -1 0 0t``l ~ ~1 ~3 ~ ~ O

O
H I O co O O O O o o I ~1 1 ~rl ~1 H I u~ 7 ~; o o ~
Ul ~H I ~ ~ (~ O

i In H I O 01:) o o o o o o ~ I I ~) ~1 H I ~O ~ Lrl ~1 0 01~1 ` ~1 ~ ~ ~ ~ ~ ~ O
,n ~ O CO O O O O O O I i I

I
~) O Q~
S O O
U ~
~ /d o ,~ O ,~

,~ o u~ ~ O ~ ,~ ~r u ~
)-I ~ q) N I ~ ~ :> O )-I ~
o I ,~ ~ I m , .
, ~ .
.

- 2~ -~ ach of the above developer solutions was stored in a 1,000 ml conical flask in contact with air and the time necessary to have an absorbance at 500 nm higher than about 3 was measured. The time in hours is reported here-inbelow in table 6.

Tabla 6 Developer solution Oxidation time (hours) Two silver halide photographic developer solutions (XII and XIII) were prepared according to the following table 7:

- Table 7 XII XIII
_______________ Water ml 675 675 KOH 35~ g 285 292 2S25 g 65 65 1-Phenyl-4,4 dimethyl- g 0.4 0.4 -3-pyrazolidone S-Methylbenzotriazole g 0.1 0.1 DTPA.5Na 40% g 5 5 Pyruvic acid g - 3 ~r g 3 3 KCl g 2 2 . - ' ' ` ~ ' .

~ ` ~

- 27 ~

H3PO4 86% g 45 45 Hydroguinone g 30 30 Water to make 1 liter pH at 20C 11.00 11.00 The ~ pH and the absorbance values at 500 nm of the developer solutions after 3 days storage are reported in the table 8:

Table 8 Developer L~ pH Absorbance values solutions ______________ _____,_______,________ __ ________________ XII +0.38 1.128 XIII *0.10 0.121 Two photographic developer solutions (XIV and XV) were prepared according ts the following table 9:

Table 9 XIV XV
_____________________________________________________._ Water ml 675 67S
KOH 35% g 280 280 N-methyl-p-aminophenol sulfate g 2.5 2.5 5-methylbenzotriazole g 0.1 0.1 DTPA ~ 5 Na 40% g 5 5 Pyruvio acid g - 3 RBr ~ 3 3 KCl g 2 2 H3PO4 86% g 45 45 Hydroquinone g 30 30 - 2a - ~3~30~3~

Water to make 1 liter pH at 20C 11.00 11.00 The ~ pH and absorbance values at S00 nm of the de-veloper solutions afetr 3 days storage are reported in the following Table 10.

Table 10 Developer Q pH Absorbance values solutions ___________. _____________________________________________ XIV+0.25 > 3 XV 0.00 0.36

Claims (25)

1. An aqueous alkaline photographic silver halide developer composition comprising a dihydroxybenzene devel-oping agent, an auxiliary superadditive developing agent, an antifogging agent, an antioxidant compound and a buff-ering agent, characterized by containing a stabilizing amount of an .alpha.-ketocarboxylic acid compound.

2. The photographic silver halide developer composi-tion of claim 1 wherein the .alpha.-ketocarboxylic acid compound corresponds to the following formula:
R-CO-COOH (I) wherein R represents a hydrogen atom or an organic group.

3. The photographic silver halide developer composi-tion of claim 1 wherein said .alpha.-ketocarboxylic acid com-pound is HOOC-CO-COOH.

4. The photographic silver halide developer composi-tion of claim 1 wherein said .alpha.-ketocarboxylic acid com-pound is H3C-CO-COOH.

5. The photographic silver halide developer composi-tion of claim 1, wherein said auxiliary developing agent is selected in the class consisting of 3-pyrazolidone and p-aminophenol compound.

6. The photographic silver halide developer composi-tion of claim 1, wherein the dihydroxybenzene developing agent is hydroquinone.

7. The photographic silver halide developer composition of claim 1, wherein the antifogging agents are selected within the group of the alkali metal halides.

8. The photographic silver halide developer composi-tion of claim 1, wherein the antioxidant compounds are selected within the group of alkali metal sulphites and ascorbic acid.

9. The photographic silver halide developer composi-tion of claim 1, wherein the antifogging agents are se-lected within the group consisting of benzotriazole and benzimidazole compound.

10. The photographic silver halide developer composi-tion of claim 1, wherein the buffering agents are selected within the group of alkali metal carbonates, borates and phosphates.

11. The photographic silver halide developer composi-tion of claim 1, comprising a sequestering agent selected within the group consisting of aminopolycarboxylic acid compounds, .alpha.-hydroxycarboxylic acid compounds, dicarboxy-lic acid compounds and polyphosphate compounds.

12. The photographic silver halide developer composi-tion of claim 1, comprising an alkanolamine compound.

13. The photographic silver halide developer composi-tion of claim 1, comprising a hydroxymethylidine group containing compound of the following formula:

(II) wherein R1 and R2 each independently represents a hydrogen atom, an aliphatic group, an aromatic group, a heterocycl-ic group, or R1 and R2 together complete a non aromatic cyclic group.

14. A photographic silver halide developer composi-tion comprising:
(a) a dihydroxybenzene developing agent in an amount of 0.04 to 0.7 moles per liter;
(b) an auxiliary developing agent in an amount of 0.0001 to 0.15 moles per liter;
(c) an inorganic antifogging agent in an amount of 0.001 to 0.2 moles per liter;
(d) an antioxidant compound in an amount of 0.001 to 1 moles per liter;
(e) a buffering compound in an amount of 0.02 to 1 moles per liter;
(f) a sequestering agent in an amount of 1x10-4 to 0.2 moles per liter;
(g) an organic antifogging agent in an amount of 1x10-5 to 5x10-2 moles per liter;
(h) an .alpha.-ketocarboxylic acid compound in an amount of 5x10-5 to 3x10-1 moles per liter;
(i) an inorganic alkali agent to have a pH in the range 9 to 13, and (l) water to make up one liter.

15. A photographic silver halide developer composi-tion comprising:
(a) a dihydroxybenzene developing agent in an amount of 0.04 to 0.7 moles per liter;
(b) an auxiliary developing agent in an amount of 0.0001 to 0.15 moles per liter;
(c) an inorganic antifogging agent in an amount of 0.001 to 0.2 moles per liter;
(d) an antioxidant compound in an amount of 0.001 to 1 moles per liter;
(e) an alkanolamine compound in an amount of 0.009 to 0.85 moles per liter;
(f) a buffering compound in an amount of 0.02 to 1 moles per liter;
(g) a sequestering agent in an amount of 1x10-4 to 0.2 moles per liter;
(h) an organic antifogging agent in an amount of 1x10-5 to 5x10-2 moles per liter;
(i) an a-ketocarboxylic acid compound in an amount of 5x10-5 to 3x10-1 moles per liter;
(l) an inorganic alkali agent to have a pH in the range 10 to 12, and (m) water sufficient to make up one liter.

16. A photographic silver halide developer composi-tion comprising:
(a) a dihydroxybenzene developing agent in an amount of 0.04 to 0.7 moles per liter;
(b) an auxiliary developing agent in an amount of 0.0001 to 0.15 moles per liter;
(c) an inorganic antifogging agent in an amount of 0.001 to 0.2 moles per liter;
(d) an antioxidant compound in an amount of 0.001 to 1 moles per liter;
(e) a hydroxymethylidine group containing compound of the following formula:

(II) wherein R1 and R2 each indipendently represent a hy-drogen atom, an aliphatic group, an aromatic group, a hetero cyclic group or R1 and R2 together complete a non-aromatic cyclic group, in an amount of 0,001 to 3 moles per liter;
(f) a buffering compound in an amount of 0.02 to 1 moles per liter;
(g) a sequestering agent in an amount of 1x10-4 to 0.2 moles per liter;
(h) an organic antifogging agent in an amount of 1x10-5 to 5x10-2 moles per liter;
(i) an a-ketocarboxylic acid compound in an amount of 5x10-5 to 3x10-1 moles per liter;

(l) an inorganic alkali agent in an amount to have a pH
in the range 10 to 12, and (m) water sufficient to make up one liter.

17. A process for forming a black and white photo-graphic silver image by development of a light-sensitive silver halide photographic element in an aqueous alkaline developer composition as claimed in any one of claims 1 to 16.

18. A process according to claim 17 for forming a black and white high-contrast negative photographic silver image by development of a silver halide photographic ele-ment, including at least a negative acting surface latent image-type silver halide emulsion layer, in the presence of a hydrazine compound.

19. The process of claim 18 wherein the silver halide element is developed in the presence of a contrast promot-ing amount of a compound selected from the group consist-ing of an alkanolamine and a hydroxymethylidine group con-taining compounds.

20. The process of claim 18 wherein the hydroxyme-thylidine group containing compound is included in the silver halide developer composition.

21. The process of claim 18 wherein the hydroxyme-thylidine group containing compound corresponds to the following formula:

wherein R1 and R2 each independently represent a hydrogen atom, an aliphatic group, an aromatic group, a heterocycl-ic group, or R1 and R2 together complete a non aromatic ciclic group.

22. The process of claim 18 wherein the hydroxyme-thylidine group containing compound is included in the silver halide photographic element.

23. The process of claim 22 wherein the hydroxyme-thylidine group containing compound is a diarylcarbinol compound according to one of the following formulas:
R3R4R5COH (III) R3R4R5C(CH2)mOH (IV) wherein R3 and R4 each represent an aryl group, R5 repre-sents a hydrogen atom, an alkyl group or an aryl group and m represents a positive integer from 0 to 4.

24. The process of claim 18 wherein the hydrazine compound is included in the silver halide photographic element.

25. The process of claim 24 wherein the hydrazine compound corresponds to the following formula:
R14-NHNH-?-R15 (VII) wherein R14 represents an aryl group and R15 represents a hydrogen atom, an alkyl group or an aryl group.