WO1987007039A2

WO1987007039A2 - High contrast development of photographic elements

Info

Publication number: WO1987007039A2
Application number: PCT/US1987/001008
Authority: WO
Inventors: Ronald J. Nothnagle; James H. Barrows; Paul A. Zielinkski
Original assignee: Eastman Kodak Company
Priority date: 1986-05-14
Filing date: 1987-05-04
Publication date: 1987-11-19
Also published as: EP0267264B1; WO1987007039A3; JPS63503247A; EP0267264A1

Abstract

High contrast development of photographic elements, such as lithographic films used in the field of graphic arts, is carried out in the presence of a hydrazine compound with an aqueous alkaline developing solution which has a pH of above 10 and below 12 and contains a dihydroxybenzene developing agent, an auxiliary super-additive developing agent, a sulfite preservative, and a contrast-promoting amount of a hydroxyalkylated piperidine compound. The developing solution combines the advantages of high capacity, a high degree of stability, and a long effective life, while providing excellent contrast and speed characteristics.

Description

HIGH CONTRAST DEVELOPMENT OF
PHOTOGRAPHIC ELEMENTS
FIELD OF THE INVENTION
This invention relates in general to photography and in particular to the black-and-white development of photographic elements. More specifically, this invention relates to the development of high contrast photographic elements, such as lithographic films used in the field of graphic arts.

BACKGROUND OF THE INVENTION
High contrast development of lithographic films is ordinarily carried out using special developers which are known in the art as "lith" developers. In conventional "lith" developers, high contrast is achieved using the "lith effect" (also referred to as infectious development) as described by J. A. C. Yule in the Journal of the Franklin
Institute, Vol. 239, 221-230, (1945). This type of development is believed to proceed autocatalytically.

To achieve lith effect" development, a low, but critical, concentration of free sulfite ion is maintained by use of an aldehyde bisulfite adduct, such as sodium formaldehyde bisulfite, which, in effect, acts as a sulfite ion buffer. The low sulfite ion concentration is necessary to avoid interference with the accumulation of developing agent oxidation products, since such interference can result in prevention of infectious development. The developer typically contains only a single type of developing agent, namely, a developing agent of the dihydroxybenzene type, such as hydroquinone.

Conventional "lith" developers suffer from serious deficiencies which restrict their usefulness.

For example, the developer exhibits low capacity as a result of the fact that it contains hydroquinone as the sole developing agent. Also, the aldehyde tends to react with the hydroquinone to cause undesirable changes in development activity.

Furthermore, the low sulfite ion concentration is inadequate to provide effective protection against aerial oxidation. As a result, a conventional "lith" developer is lacking in stability and tends to give erratic results depending on the length of time that it has been exposed to the air.

An alternative to the use of conventional "lith" developers is disclosed in Nothnagle, U. S.

Patent No. 4,269,929, High Contrast Development Of
Photographic Elements," issued May 26, 1981, the disclosure of which is incorporated herein by reference. As described in this patent, high contrast development of photographic elements is carried out in the presence of a hydrazine compound with an aqueous alkaline developing solution which has a pH of above 10 and below 12 and contains a dihydroxybenzene developing agent, a 3-pyrazolidone developing agent, a sulfite preservative, and a contrastpromoting amount of an amino compound. The developing solution combines the advantages of high capacity, a high degree of stability, and a long effective life, while providing excellent contrast and speed characteristics.

U. S. patent 4,269,929 describes the use of a very wide variety of amino compounds as contrast promoting agents. In particular, it discloses the use of both inorganic amines, such as the hydroxylamines, and organic amines, including aliphatic amines, aromatic amines, cyclic amines, mixed aliphatic-aromatic amines, and heterocyclic amines.

Primary, secondary and tertiary amines, as well as quaternary ammonium compounds, are included within the broad scope of the disclosure.

While the invention of U. S. patent 4,269,929 represents a very important advance in the art, its commercial utilization has been hindered by the disadvantageous characteristics exhibited by many amino compounds. Thus, for example, some amines suffer from the problem of toxicity, some from the problem of excessive volatility, some are characterized by highly unpleasant odors, some.tend to form azeotropes with water, some exhibit an inadequate degree of solubility in an aqueous alkaline photograD phic developing solution, and some are costly yet must be used at a relatively high concentration such that they constitute a substantial portion of the total cost of the developing solution. Moreover, many amines exhibit a degree of activity as contrastpromoters in the method and composition of U. S.

patent 4,269,929 that is less than is desired for commercial operation.

It is toward the objective of providing contrast-promoting agents which do not suffer from any of the aforesaid disadvantages, and are, therefore, especially advantageous for use in the invention of U. S. patent 4,269,929, that the present invention is directed.

SUMMARY OF THE INVENTION
In accordance with this invention, it has been discovered that unexpectedly superior per for mance in photographic developing methods and compositions of the type described in U. S. patent 4,269,929 is achieved with one particular sub-class of amino compounds, namely hydroxyalkylated piperidine compounds. Thus, in the present invention, high contrast development of a photographic element is carried out in the presence of a hydrazine compound with an aqueous alkaline developing solution which has a pH of above 10 and below 12, and contains a dihydroxybenzene developing agent, an auxiliary super-additive developing agent, a sulfite preservative, and a contrast-promoting amount of an hydroxyalkylated piperidine compound.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
Photographic elements which can be processed in the novel high contrast developing solutions of this invention are not limited to "lith" films.

Typically, Alith films contain high chloride emulsions (at least about 60 percent by weight silver chloride based on total silver halide). most usually in the form. of silver chlorobromides or. silver chlorobromoiodides. Such films give excellent results when used in the novel high contrast developing solutions of this invention. However, the novel high contrast developing solutions of this invention can also be usefully employed with other types of silver halide photographic elements, for example with elements utilizing silver bromide or silver bromoiodide emulsions. To achieve the benefits of this invention, the hydrazine compound can be incorporated in the photographic element or in the developing solution, the essential requirement being that it be present during development of the exposed element.

Incorporatios of a hydrazine compound in both the photographic element and in the developing solution is, of course, a further alternative that can be utilized where it is desired to do so.

The contrast or "gamma8 of a photographic element refers to the rate of change of density with exposure and is measured by the slope of the straight line portion of the characteristic curve. Photographic elements processed in the novel developing solutions of this invention typically exhibit very high contrast, by which is meant a gamma of greater than 10.

As used herein, the term "a hydrazine compound" is intended to include hydrazine and hydrazine derivatives, including those which are suited for incorporation in developing solutions and those which are suited for incorporation in photographic elements.

Hydrazine (H2N-NH2) is an effective contrast-promoting agent which can be incorporated in the developing solutions of this invention. As an alternative to the use of hydrazine, any of a widë variety of water-soluble hydrazine derivatives can be added to the developing solution. Preferred hydrazine derivatives for use in the developing solutions of this invention include organic hydrazine compounds of the formula:
EMI5.1
where R1 is an organic radical and each of R2,
R3 and R4 is a hydrogen atom or an organic radical. Organic radicals represented by R1,
R2, R3 and R4 include hydrocarbyl groups such as an alkyl group, an aryl group, an aralkyl group, an alkaryl group, and an alicyclic group, as well as hydrocarbyl groups substituted with substituents such as alkoxy groups, carboxy groups, sulfonamido groups, and halogen atoms.

Particularly preferred hydrazine derivatives for incorporation in the developing solutions of this invention include alkylsulfonamido aryl hydrazines such as p-(methylsulfonamido)phenylhydrazine and alkylsulfonamidoalkyl aryl hydrazines such as p-(methylsulfonamidomethyl)phenylhydrazine.

In the practice of this invention, it is preferred that the hydrazine compound be incorporated in the photographic element. For example, it can be incorporated in a silver halide emulsion used in forming the photographic element. Alternatively, the hydrazine compound can be present in a hydrophilic colloid layer of the photographic element, preferably a hydrophilic colloid layer which is coated to be contiguously adjacent to the emulsion layer in which the effects of the hydrazine compound are desired.

It can, of course, be present -in the photographic element distributed between or among emulsion and hydrophilic colloid layers, such as undercoating layers, interlayers, and overcoating layers.

Photographic elements which are particularly preferred for use in the method of this invention include elements containing a hydrazine compound of the formula:
EMI6.1
wherein R1 is a phenyl nucleus having a Hammett sigma value-derived electron withdrawing character is- tic of less than +0.30.

In the above formula, R1 can take the form of a phenyl nucleus which is either electron donating (electropositive) or electron withdrawing (electronegative); however, phenyl nuclei which are highly electron withdrawing produce inferior nucleating agents. The electron withdrawing or electron donating characteristic of a specific phenyl nucleus can be assessed by reference to
Hammett sigma values. The phenyl nucleus can be assigned a Hammett sigma value-derived electron withdrawing characteristic which is the algebraic sum of the Hammett sigma values of its substituents (i.e., those of the substituents, if any, to the phenyl group).

For example, the Hammett sigma values of any substituents to the phenyl ring of the phenyl nucleus can be determined algebraically simply by determining from the literature the known Hammett sigma values for each substituent and obtaining the algebraic sum thereof. Electron donating substituents are assigned negative sigma values.

For example, in one preferred form, R1 can be a phenyl group which is unsubstituted. The hydrogens attached to the phenyl ring each have a Hammett sigma value of O by definition. In another form, the phenyl nuclei can include halogen ring substituents.

For example, ortho- or Para-chloro or fluoro substituted phenyl groups are specifically contemplated, although the chloro and fluoro groups are each mildly electron withdrawing.

Preferred phenyl group substituents are those which are not electron withdrawing. For example, the phenyl groups can be substituted with straight or branched chain alkyl groups Ce.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-hexyl, noctyl, tert-octyl, n-decyl, n-dodecyl and similar groups). The phenyl groups can be substituted with alkoxy groups wherein the alkyl moieties thereof can be chosen from among the alkyl groups described above. The phenyl groups can also be substituted with acylamino groups.

Illustrative acylamino groups include acetylamino, propanoylamino, butanoylamino, octanoylamino, benzoylamino, and similar groups.

In one particularly preferred form the alkyl, alkoxy andlor acylamino groups are in turn substituted with a conventional photographic ballast, such as. the ballasting moieties of incorporated couplers and other immobile photographic emulsion addenda. The ballast groups typically contain at least eight carbon atoms and can be selected from both aliphatic and aromatic relatively unreactive groups, such as alkyl, alkoxy, phenyl, alkylphenyl, phenoxy, alkylphenoxy and similar groups.

The alkyl and alkoxy groups, including ballasting groups, if any, preferably contain from 1 to 20 carbon atoms, and the acylamino groups, including ballasting groups, if any, preferably contain from 2 to 21 carbon atoms. Generally, up to about 30 or more carbon atoms in these groups are contemplated in their ballasted form. Methoxyphenyl, tolyl (e.g., p-tolyl and m-tolyl) and ballasted butyramidophenyl nuclei are specifically preferred.

Examples of specifically preferred hydrazine compounds are the following:
l-Formyl-2-(4- [ 2-(2 ,4-di-tert-pentylphenoxy)- butyramido ] phenyl)hydrazine
EMI8.1
l-Formyl-2-phenylhydrazine
EMI9.1
l-Formyl-2-(4-methoxylphenyl)hydrazine
EMI9.2
l-Formyl-2-(4-chlorophenyl )hydrazine
EMI9.3
l-Formyl-2-(4-fluorophenyl)hydrazine
EMI9.4
l-Formyl-2-(2-chlorophenyl)hydrazine
EMI9.5
l-Formyl-2-(p-tolyl)hydrazine
EMI9.6

Preferred photographic elements for use in the method of this invention also include those in which the hydrazide comprises an adsorption promoting moiety. Hydrazides of this type contain an unsubstituted or mono-substituted divalent hydrazo moiety and an acyl moiety.

The adsorption promoting moiety can be chosen from among those known to promote adsorption of photographic addenda to silver halide grain surfaces. Typically, such moieties contain a sulfur or nitrogen atom capable of complexing with silver or otherwise exhibiting an affinity for the silver halide grain surface. Examples of preferred adsorption promoting moieties include thioureas, heterocyclic thioamides and triazoles.

Exemplary hydrazides containing an adsorption promoting moiety include:
1-[4-(2-formylhydrazino)phenyl]-3-methyl thiourea
3-[4-(2-formylhydrazino)phenyl-5-(3-methyl-2- benzoxazolinylidene)rhodanine-6-( #4-(2-formylhydra- zino)phenyl ] ureylene)-2-methylbenzothiazole
N-(benzotriazol-5-yl )-4-( 2-formylhydraz ino )- phenylacetamide
N#(benzotriazol-5-yl )-3-( 5-formylhydrazino-2- methoxyphenyl)propionamide and N-2-(5,5-dimethyl-2 thioimidazol-4-yl-idenimino)ethyl-3- [ 5-( formylhydra- zino)-2-methoxyphenyl)propionamide.

Hydrazine compounds incorporated in the developing solution in the practice of this invention are effective at very low levels of concentration.

For example, hydrazine gives effective results in the developing solution in an amount of only 0.1 grams per liter. Hydrazine compounds incorporated in the photographic element are typically employed in a concentration of from about 10-4 to about 10-1 mole per mole of silver, more preferably in an amount of from about 5 x 10-4 to about 5 x 10-2 mole per mole of silver, and most preferably in an amount of from about 8 x 10-4 to about 5 x 10-3 mole per mole of silver. The hydrazides containing an adsorption promoting moiety can be used at a level as low as about 5 x 10 6 mole per mole of silver.

The dihydroxybenzene developing agents employed in the aqueous alkaline developing solutions of this invention are well known and widely used in photographic processing. The preferred developing agent of this class is hydroquinone. Other useful dihydroxybenzene developing agents include:
chlorohydroquinone,
bromohydroquinone,
isopropylhydroquinone,
toluhydroquinone,
methylhydroquinone,
2,3-dichlorohydroquinone,
2,5-dimethylhydroquinone,
2,3-dibromohydroquinone,
1, 4-dihydroxy-2-acetophenone-2, 5-dimethyl-
hydroquinone,
2,5-diethylhydroquinone,
2,5-di-p-phenethylhydroquinone,
2, 5-dibenzoylaminohydroquinone,
2,5-diacetaminohydroquinone, and the like.

The auxiliary super-additive developing agents employed in the aqueous alkaline developing solutions of this invention are also well known and widely used in photographic processing. As explained in Mason, "Photographic Processing Chemistry", Focal
Press, London, 1975, "super-additivity" refers to a synergistic effect whereby the combined activity of a mixture of two developtng agents is greater than the sum of the two activities when each agent is used alone in the same developing solution (Note especially the paragraph entitled, "Superadditivity" on Page 29 of Mason).

For the purposes of this invention, the preferred auxiliary super-additive developing agents are the 3-pyrazolidone developing agents.

Particularly preferred developing agents of this class are those represented by the formula:
EMI12.1
in which R1 is aryl (including substituted aryl) and R2, R3, and R4 are hydrogen or alkyl (including substituted alkyl). Included within the definition of R1 are phenyl and phenyl substituted with groups such as methyl, chloro, amino, methylamino, acetylamino, methoxy and methylsulfonamidoethyl. Included within the definition of R2, R3 and R4 are unsubstituted alkyl and alkyl substituted with groups such as hydroxy, carboxy, or sulfo.

The most commonly used developing agents of this class are l-phenyl-3-pyrazolidone, 1-phenyl-4,4dimethyl-3-pyrazolidone, l-phenyl-4-methyl-4-hydroxymethyl-3-pyrazolidone and l-phenyl-4, 4-dihydroxy- methyl-3-pyrazolidone. Other useful 3-pyrazolidone developing agents include:

:
l-phenyl-5-methyl-3-pyrazolidone,
l-phenyl-4, 4-diethyl-3-pyrazolidone,
l-p-aminophenyl-4-methyl-4-propyl-3
pyrazolidone,
1-p-chlorophenyl-4-methyl 4 ethyl-3-
pyrazolidone,
1-p-acetamidophenyl-4,4-diethyl-3-pyrazolidone,
l-p-betahydroxyethylphenyl-4, 4-dimethyl-3-pyra-
zolidone,
l-p-hydroxyphenyl-4, 4-dimethyl-3-pyrazolidone,
l-p-methoxyphenyl-4,4-diethyl-3-pyrazolidone,
l-p-tolyl-4,4-dimethyl-3-pyrazolidone, and the like.

Less preferred but also useful auxiliary super-additive developing agents for use in the aqueous alkaline developing solutions of this invention are the aminophenols. Examples of useful aminophenols include:
p-aminophenol
o-aminophenol
p-methylaminophenol sulfate
2,4-diaminophenol hydrochloride
N-( 4-hydroxyphenyl )glycine
p-benzylaminophenol hydrochloride
2,4-diamino-6-methylphenol
2, 4-diaminoresorcinol
N-(beta-hydroxyethyl )-p-aminophenol
and the like.

More than one auxiliary super-additive developing agent can be incorporated in the developing solutions of this invention, if desired.

For example, the developing solution can contain hydroquinone, 1-phenyl-3-pyrazolidone, and p-methylaminophenol sulfate. More than one dihydroxybenzene developing agent can, of course, also be utilized, if desired.

The aqueous alkaline photographic developing compositions of this invention contain a sulfite preservative at a level sufficient to protect the developing agents against aerial oxidation and thereby promote good stability characteristics.

Useful sulfite preservatives include sulfites, bisulfites, metabisulfites, and carbonyl bisulfite adducts. Typical examples of sulfite preservatives include:
sodium sulfite,
potassium sulfite,
lithium sulfite,
ammonium sulfite,
sodium bisulfite,
potassium metabisulfite,
sodium formaldehyde bisulfite, and the like.

In accordance with this invention, an hydroxyalkylated piperidine compound is incorporated in the aqueous alkaline developing solution in a contrast-promoting amount; the term "an hydroxyalkylated piperidine compound" being used herein to mean a compound comprising at least one piperidine ring and at least one hydroxyalkyl group. The use of an hydroxyalkylated piperidine compound permits high contrast development in the presence of a hydrazine compound to be accomplished at low pH levels as compared to the pH level needed to achieve the same contrast without the use of an hydroxyalkylated piperidine compound. The use of an hydroxyalkylated piperidine compound also permits high contrast development in the presence of a hydrazine compound to be carried out at lower pH levels than does the use of many of the other amino compounds.

The advantages of being able to carry out development at low pH levels will be readily apparent to those skilled in the art of photographic processing. For example, with the use of a low pH level, the developing solution is much less hazardous and its effective life is greatly enhanced.

The aqueous alkaline developing solutions of this invention can vary widely in regard to the concentration of the various ingredients included therein. Typically, the dihydroxybenzene developing agent is used in an amount of from about 0.045 to about 0.65 moles per liter, more preferably in an amount of about 0.09 to about 0.36 moles per liter; the auxiliary super-additive developing agent is used in an amount of from about 0.0005 to about 0.01 moles per liter, more preferably in an amount of from about 0.001 to about 0.005 moles per liter; the sulfite preservative is used in an amount of from about 0.04 to about 0.80 moles per liter, more preferably in an amount of from about 0.12 to about 0.60 moles per liter;

and the hydroxyalkylated piperidine compound is used in an amount of from about 0.001 to about 0.15 moles per liter, more preferably in an amount of from about 0.002 to about 0.1 moles per liter.

As mentioned under BACKGROUND OF THE
INVENTION hereinabove, many factors are involved in assessing the suitability of an amino compound for use as a contrast-promoting agent in the invention of U. S. patent 4,269,929. Thus, a compound which is acceptable on the basis of activity, i.e., contrast-promoting and speed-promoting ability, may be unacceptable because of its toxicity, or because of its odor, or because it is sufficiently volatile that it forms deposits on processing equipment, or because it forms azeotropes with water and, es a consequence, tends to form deposits on processing equipment. Moreover, many amino compounds are not sufficiently water-soluble to be used in the developing solution at an effective concentration, and many amino compounds are unsatisfactory because of their inability to provide good halftone dot quality.

A particularly important factor is "discrimination", a term which is used herein to describe the ratio of the extent of shoulder development to "pepper fog" level. Good discrimination, i.e., full shoulder development with low pepper fog, is necessary to obtain good halftone dot quality.

(The term "pepper fog" is commonly utilized in the photographic art, and refers to fog of a type characterized by numerous fine black specks).

An extensive experimental evaluation of amino compounds has established, most unexpectedly, that one subclass of amino compounds, namely the hydroxyalkylated piperidine compounds, meets all the criteria necessary to provide optimum performance in the invention of U. S. patent 4,269,929. Thus, the hydroxyalkylated piperidine compounds are highly active, have an adequate degree of solubility, exhibit very low volatility, have no azeotropic characteristics, are non-toxic, exhibit no odor, and provide very low pepper fog, excellent discrimination and excellent halftone dot quality.

Preferred hydroxyalkylated piperidine compounds for use in this invention include compounds of the formula:
EMI16.1
where each n is independently an integer with a value of from 1 to 4, and compounds of the formula:
EMI16.2
where R1 amd R2 are independently selected from the group consisting of hydrogen, alkyl groups of 1 to 6 carbon atoms, and radicals of the formula:
EMI17.1
where X is O to 3, y is O to 3, and Z is 1 to 3, with the proviso that at least one of R1 and R2 is a radical of the above formula.

The compound 1,3-di(N-2-hydroxyethyl-4piperidyl)propane, which is a well known compound that is commercially available, is illustrative of compounds of formula I above. It has the formula:
EMI17.2

An alternative name for this compound is 4,4'-(l,3-propanediyl)-bis-l,l'-piperidineethanol.

Illustrative examples of hydroxyalkylated piperidine compounds of Formula II above include:
EMI17.3
l-methyl-2-piperidinemethanol
EMI17.4
l-methyl-3-piperidinemethanol
EMI18.1
l-piperidineethanol
EMI18.2
3-piperidino-1,2-propanediol
Compounds of Formula II are also well known, and many are commercially available.

The very high degree of activity as a contrast-promoting agent exhibited by the hydroxyalkylated piperidine compounds is of particular benefit in permitting the use of lower pH levels than is feasible with many other amino compounds, with resulting improvement in the effective life of the developing solution, that is, the length of time that it can be used or stored and still provide acceptable development characteristics. Generally speaking, the greater the amount of hydroxyalkylated piperidine compound utilized, the lower the pH needed to achieve the desired high contrast level.

It is a further particular advantage of the present invention that the hydroxyalkylated piperidine compounds can be used at very low concentration levels such as levels of a few grams per liter and, in some instances, as low as one gram per liter or less and still provide very high contrast. This is important for reasons of economy, since the cost of the amino compound can be a substantial portion of the cost of the entire developing solution, and use of very low concentrations of the amino compound provides very significant cost savings. Certain of the amino compounds employed in the working examples of U. S. patent 4,269,929 also provided very high contrast when used at very low concentration levels.

For example, as shown in Table II of U. S. patent 4,269,929, l,4-cyclohexanebis(methylamine) provided a contrast of 16.67 at a concentration of 1 gram per liter and triethylamine provided a contrast of 20.00 at a concentration of 5 grams per liter. However, these compounds suffer from serious disadvantages which render impractical their commercial utilization in the method and composition of U. S. patent 4,269,929. For example, l,4-cyclohexane-bis(methyl- amine) is unsatisfactory because of very high pepper fog and poor halftone dot quality, while triethyl- amine is unsatisfactory because of a severe odor problem.

The aqueous alkaline developing solutions of this invention have a pH of above 10 and below 12.

The preferred pH range for the aqueous alkaline developing solutions of this invention is from 10.3 to 11.8. A particularly preferred pH range is from 11.2 to 11.6.

As explained in U. S. patent 4,269,929, alkaline agents whose function is to control pH, such as carbonates or phosphates, can be included in the developing solution, if necessary, but adequate control of pH can also be provided by amino compounds.

In some instances, it will be useful to utilize two different amino compounds, one to promote contrast and one to control pH. Thus, for example, a particularly useful developing solution is one which is free of pH buffers such as carbonates or phosphates, which contains 2-methylaminoethanol in an amount sufficient to provide the desired pH, and which contains a contrast-promoting amount of an hydroxyalkylated piperidine compound. This developing solution is particularly useful in combination with a hardening fix, since it avoids the problems of precipitate formation that can occur when a developing solution containing a phosphate buffer is used in combination with a hardening fix.

In contrast with conventional "lith" developers which require a low level of sulfite ion, the developing solutions of this invention can utilize much higher levels of sulfite ion, and thereby achieve the advantage of increased stability, since the higher level of sulfite ion provides increased protection against aerial oxidation.

In carrying out the method of this invention, it is preferred to employ one or more organic anti¯ foggants to minimize fog formation. The organic antifoggants can be incorporated in the photographic element or they can be added to the developing solution, the essential requirement being that they be present during the developing process. Particularly advantageous results are achieved with the use of benzotriazole antifoggants. A further preferred class of organic antifoggants are the mercapto azole antifoggants. Inorganic antifoggants, or restrainers, such as-alkali metal bromides, can be utilized in conjunction with the use of an organic antifoggant, if desired.

Particularly preferred benzotriazole antifoggants for use in the developing solutions of this invention are benzotriazole, halo-substituted benzotriazoles such as 4-chlorobenzotriazole; 4-bromobenzo- triazole and 5-chlorobenzotriazole, and alkyl-sub stituted benzotriazoles such as 5-methylbenzotriazole.

Preferred mercapto azole antifoggants are those represented by the formula:
EMI21.1
wherein Z represents the atoms necessary to complete 5 or 6 member heterocyclic ring, such as pyrimidine, triazine, tetrazole, triazole, imidazole, diazole, oxadiazole or thiadiazole ring; and SX represents a mercapto function, n being a whole number, typically number from 1 to about 3, any free bonds being satisfied by hydrogen atoms. In the mercapto function or group, X is a cation which includes hydrogen, an alkali metal, e.g., sodium or potassium, ammonium or an organic amine residue of such amines as triethyl amine, triethanol amine, morpholine and the like.

Mercapto tetrazole antifoggants are especially suitable in the practice of this invention and include those of the formula:
EMI21.2
wherein R is an aliphatic or aromatic radical containing up to about 30 carbon atoms and SX is a mercapto function.

Specific examples of mercapto azole antifoggants include:
mercapto-substituted pyrimidines such as:
thiobarbituric acid and thiouracil,
mercapto-substituted oxadiazoles or thiadiazoles such as:
5-phenyl-2-mercapto-1,3,4-oxadiazole and
5-o-toryl-2-mercapto-1,3,4-thiadiazole,
mercapto triazines such as: 2,4,6-trimercapto
1,3,5-triazine,
mercapto imidazoles such as:
2-mercapto-5-phenylimidazole,
condensed imidazoles such as:
2-mercaptobenzimidazole, triazoles such as:
3,4-diphenyl-5-mercapto-1,2,4-triazole and
3-mercapto-5-methyl-1,2,4-triazole,
mercapto tetrazoles such as:
l-phenyl-5-mercaptotetrazole and
l-(3-capramido)phenyl-5-mercaptotetrazole.

The combination of 5-methylbenzotriazole and l-phenyl-5-mercaptotetrazole is preferred for antifoggant use in the aqueous alkaline developing solutions of this invention, while the combination of benzotriazole, 5-methylbenzotriazole and l-phenyl-5mercaptotetrazole is particularly preferred.

Photographic elements processed in the aqueous alkaline developing solutions of this invention comprise one or more layers formed from a negative-working silver halide emulsion comprised of a binder and radiation-sensitive silver halide grains capable of forming a surface latent image. The useful silver halide emulsions include the high chloride emulsions conventionally employed in forming "lith" photographic elements as well as silver bromide and silver bromoiodide emulsions, which are recognized in the art to be capable of attaining higher photographic speeds. Generally, the iodide content of the silver halide emulsions is less than about 10 mole percent silver iodide, based on total silver halide.

The silver halide grains of the emulsions are capable of forming a surface latent image, as opposed to being of the internal latent image-forming type. Surface latent image silver halide grains are employed in the overwhelming majority of negative¯ working silver halide emulsions, whereas internal latent image-forming silver halide grains, though capable of forming a negative image when developed in an internal developer, are usually employed with surface developers to form direct-positive images.

The distinction between surface latent image and internal latent image silver halide grains is generally well recognized in the art. Generally, some additional ingredient or step is required in preparation to form silver halide grains capable of preferentially forming an internal latent image as compared to a surface latent image.

The silver halide emulsions can be spectrally sensitized with dyes from a variety of classes, including the polymethine dye class, which includes the cyanines, merocyanines, complex cyanines and merocyanines (i.e., tri-, tetra- and poly-nuclear cyanines and merocyanines), oxonols, hemioxonols, styryls, merostyryls and streptocyanines.

In addition to the essential components specified hereinabove, the developing solutions of this invention can optionally contain any of a wide variety of addenda known to be useful in photographic developing compositions. For example, they can contain solvents, buffers, sequestering agents, development accelerators, agents to reduce swelling of the emulsion layers, and the like.

In processing photographic elements with the developing solutions described herein, the time and temperature employed for development can be varied widely. Typically, the development temperature will be in the range of from about 200C (680F) to about 50 C (122 F), more preferably in the range of from about 25 0C (77OF) to about 400C (1040F), while the development time will be in the range of from about 10 seconds to about 150 seconds, more preferably in the range of from about 20 seconds to about 120 seconds.

The invention is further illustrated by the following examples of its practice.

Example 1
Developing solutions similar to those described in the working examples of U. S. patent 4,269,929, except that the amino compound utilized as a contrast-promoting agent was l,3-di(N-2-hydroxy- ethyl-4-piperidyl)propane, were prepared and evaluated in a similar manner to that described in the aforesaid patent. Excellent results were obtained with concen- trations of l,3-di(N-2-hydroxyethyl-4-piperidyl) propane as low as one gram per liter. In particular developing solutions containing l,3-di(N-2-hydroxy- ethyl-4-piperidyl)propane at a concentration of as low as one gram per liter were found to provide low fog, high speed, excellent halftone dot quality and an average contrast of at least fifteen.

Moreover, these solutions exhibited no unpleasant odor and were free from the problem of formation of unwanted deposits on processing equipment that occurs in using amines which exhibit significant volatility.

Example 2
Developing solutions were prepared as in
Example 1, except that the amino compound was l-methyl-2-piperidinemethanol and similar results were obtained.

Example 3
Developing solutions were prepared as in
Example 1, except that the amino compound was l-methyl-3-piperidinemethanol and similar results were obtained.

Example 4
Developing solutions were prepared as in
Example 1, except that the amino compound was l¯piperidineethanol and similar results were obtained.

Example 5
Developing solutions were prepared as in
Example 1, except that the amino compound was 3-piperidino-1,2-propanediol and similar results were obtained. With this amino compound, the optimum concentration in the developing solution was about 15 grams per liter.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

Claims

WE CLAIM:

1. A method for high contrast development of a photographic element comprising at least one silver halide emulsion layer, which method comprises contacting said element in the presence of a hydrazine compound with an aqueous alkaline developing solution which has a pH of above 10 and below 12 and contains a dihydroxybenzene developing agent, an auxiliary super-additive developing agent, a sulfite preservative, and a contrast-promoting amount of an hydroxyalkylated piperidine compound.

2. A method for high contrast development of a photographic element comprising at least one silver halide emulsion layer containing a hydrazine compound, which method comprises contacting said element with an aqueous alkaline developing solution which has a pH of above 10 and below 12 and contains a dihydroxybenzene developing agent, an auxiliary super-additive developing agent, a sulfite preservative, and a contrast-promoting amount of an hydroxyalkylated piperidine compound.

3. A method for high contrast development of a photographic element comprising at least one silver halide emulsion layer which method comprises contacting said element with-an aqueous alkaline developing solution which has a pH of above 10 and below 12 and contains a hydrazine compound, a dihydroxybenzene developing agent, an auxiliary super-additive developing agent, a sulfite preservative, and a contrast-promoting amount of an hydroxyalkylated piperidine compound.

4. A method for high contrast development of a photographic element comprising at least one silver halide emulsion layer, which method comprises contacting said element in the presence of a hydrazine compound with an aqueous alkaline developing solution which has a pH of above 10 and below 12 and contains a dihydroxybenzene developing agent, an auxiliary super-additive developing agent, a sulfite preservative, and a contrast-promoting amount of an hydroxyalkylated piperidine compound of the formula: EMI27.1 where each n is independently an integer with a value of from 1 to 4, or the formula: EMI27.2 where R1 and R2 are independently selected from the group consisting of hydrogen, alkyl groups of 1 to 6 carbon atoms, and radicals of the formula:

: EMI27.3 where X is O to 3, y is O to 3, and Z is 1 to 3, with the proviso that at least one of R1 and R2 is a radical of the above formula.

5. A method as claimed in claim 1 wherein said developing solution has a pH in the range of from 10.3 to 11.8.

6. A method as claimed in claim 1 wherein said developing solution has a pH in the range of from 11.2 to 11.6.

7. A method as claimed in claim 1 wherein said dihydroxybenzene developing agent is hydroquinone.

8. A method as claimed in claim 1 wherein said auxiliary super-additive developing agent is a 3-pyrazolidone developing agent.

9. A method as claimed in claim 1 wherein said auxiliary super-additive developing agent is an aminophenol developing agent.

10. A method as claimed in claim 1 wherein said auxiliary super-additive developing agent is l-phenyl-3-pyrazolidone.

11. -A method as claimed in claim 1 wherein said auxiliary super-additive developing agent is l-phenyl-4-hydroxymethyl-3-pyrazolidone.

12. A method as claimed in claim 1 wherein said auxiliary super-additive developing agent is l-phenyl-4,4-dimethyl-3-pyrazolidone.

13. A method as claimed in claim 1 wherein said auxiliary super-additive developing agent is pmethylaminophenol sulfate.

14. A method as claimed in claim 1 wherein said sulfite preservative is sodium sulfite.

15. A method as claimed in claim 1 wherein said developing solution additionally contains a benzotriazole antifoggant.

16. A method as claimed in claim 1 wherein said developing solution additionally contains 5-methylbenzotriazole.

17. A method as claimed in claim 1 wherein said developing solution additionally contains a combination of benzotriazole, 5-methylbenzotriazole and l-phenyl-5-mercaptotetrazole.

18. A method as claimed in claim 1 wherein said hydroxyalkylated piperidine compound is selected from the group consisting of 1, 3-di(N-2-hydroxyethyl-4-piperidyl )propane, l-methyl-2-piperidinemethanol, l-methyl-3- piperidinemethanol, l-piperidineethanol, and 3-piperidino-1, 2-propanediol.

19. A method for high contrast development of a photographic element comprising at least- one silver halide emulsion layer containing l-formyl-2 (4- [ 2-(2,4-di-t-pentylphenoxy)butyramido ] phenyl)hy- drazide, which method comprises contacting said element with an aqueous alkaline developing solution which has a pH in the range of from 11.2 to 11.6 and contains hydroquinone, l-phenyl-4 , 4-dimethyl-3-pyra- zolidone, sodium sulfite, and a contrast-promoting amount of 3-piperidino-1 , 2-propanediol.

20. A method as claimed in claim 19 wherein said developing solution contains about fifteen grams of 3-piperidino-l,2-propanediol per liter of solution.

21. An aqueous alkaline photographic developing solution for use in high contrast processing of photographic elements in the presence of a hydrazine compound, said solution having a pH of above 10 and below 12, and containing a dihydroxybenzene developing agent, an auxiliary super-additive developing agent, a sulfite preservative, and a contrast-promoting amount of an hydroxyalkylated piperidine compound.

22. An aqueous alkaline denteloping solution as claimed in claim 21 having a pH in the range of from 10.3 to 11.8.

23. An aqueous alkaline developing solution as claimed in claim 21 having a pH in the range of from 11.2 to 11.6.

24. An aqueous alkaline developing solution as claimed in claim 21 wherein said dihydroxybenzene developing agent is hydroquinone.

25. An aqueous alkaline developing solution as claimed in claim 21 wherein said auxiliary super-additive developing agent is a 3¯pyrazolidone developing agent.

26. An aqueous alkaline developing solution as claimed in claim 21 wherein said auxiliary super-additive developing agent is an aminophenol developing agent.

27. An aqueous alkaline developing solution as claimed in claim 21 wherein said auxiliary super-additive developing agent is l-phenyl-4-me thy 1- 4-hydroxy-methyl-3-pyrazolidone.

28. An aqueous alkaline developing solution as claimed in claim 21 wherein said auxiliary super-additive developing agent is 1-phenyl-4,4 dimethyl-3-pyrazol idone.

29. An aqueous alkaline developing solution as claimed in claim 21 wherein said auxiliary superadditive developing agent is p-methylaminophenol sulfate.

30. An aqueous alkaline developing solution as claimed in claim 21 wherein said sulfite preservative is sodium sulfite.

31. An aqueous alkaline developing solution as claimed in claim 21 additionally containing 2-methylaminoethanol.

32. An aqueous alkaline developing solution as claimed in claim 21 additionally containing a benzotriazole antifoggant.

33. An aqueous alkaline developing solution as claimed in claim 21 additionally containing 5-methylbenzotriazole.

34. An aqueous alkaline developing solution as claimed in claim 21 additionally containing a combination of benzotriazole, 5-methylbenzotriazole and l-phenyl-5-mercaptotetrazole.

35. An aqueous alkaline photographic developing solution for use in high contrast processing of photographic elements in the presence of a hydrazine compound, said solution having a pH of above 10 and below 12, and containing a dihydroxybenzene developing agent, an auxiliary super-additive developing agent, a sulfite preservative, and a contrast-promoting amount of an hydroxyalkylated piperidine compound of the formula: EMI32.1 where each n is independently an integer with a value of from 1 to 4, or the formula:. EMI32.2

where R1 and R2 are independently selected from the group consisting of hydrogen, alkyl groups of 1 to 6 carbon atoms, and radicals of the formula EMI32.3 where X is O to 3, y is O to 3, and Z is 1 to 3, with the proviso that at least one of R1 and R2 is a radical of the above formula.

36. An aqueous alkaline photographic developing solution for use in high contrast processing of p#otographic elements in the presence of a hydrazine compound, said solution having a pH in the range of from 10.3 to 11.8 and containing hydroquinone, l-phenyl-4, 4-dimethyl-3-pyrazolidone, sodium sulfite, and 3-piperidino-1,2-propanediol.

37. An aqueous alkaline photographic developing solution for use in high contrast processing of photographic elements, said solution having a pH of above 10 and below 12 and containing a hydrazine compound, a dihydroxybenzene developing agent, an auxiliary super-additive developing agent, a sulfite preservative, and a contrast-promoting amount of 3-piperidino-l, 2-propanediol.

38. An aqueous alkaline developing solution as claimed in claim 37 having a pH in the range of from 11.2 to 11.6.