GB2297747A - Hydrazides useful in photographic materials - Google Patents

Abstract

A hydrazide compound of the general formula 1:- wherein U is a unsubstituted or substituted alkylene or arylene group with up to 8 carbon atoms, n and m are 1 or 0 and may be equal or different, R 1 and R 2 are independently an alkyl or isoalkyl group containing 1 - 4 carbon atoms, a substituted alkyl, an alkoxy or aralkoxy group with up to 12 carbon atoms, or a halogen and where either R 1 or R 2 can also be hydrogen, or R 1 and R 2 together can form an aromatic or a partially unsaturated ring, R 3 is H or alkyl with up to 4 carbon atoms, A + is a activity regulating group, and G - is an anion, can be used in photographic silver halide materials to provide good dot quality.

Description

1. Field of the Invention This invention relates to novel hydrazide compounds, to their production and to photographic materials which comprise these compounds which are useful as dot-promoting agents in photographic image systems.. In particular the presence of these compounds in photographic silver halide material facilitates the process of forming a high contrast image which permits the production of dot and line images possessing high image quality when exposed in graphic arts cameras or when exposed by electronic scanners, film plotters, image setters using lasers or other high intensity light sources for exposure.

2. Description of the Prior Art Traditionally, the production of high quality halftone dots was obtained with the use of 'lith' films and chemistry. These films, used for making halftone and line images were capable to produce extremely high contrast and good image sharpness. Sharpness is quantified in terms of 'edge gradient' which is the ratio of change in density to distance at the boundary between the darkened part and the undarkened part of the photographic image. In general, the higher the edge gradient the sharper the image eg. the harder the dot. In the case of halftone images such properties contribute to 'high dot quality'.

Those skilled in the art attribute the formation of hard dots produced with lith materials to the high contrast obtained from infectious development as described by Yule, J. Frank. Inst.

239 221 (1945). In fact high contrast has come to be synonymous with edge gradient.

Although the dot quality delivered from lith materials is excellent, the lith system suffers serious deficiencies which restrict its utility. As has been recognised, the deficiencies of the lith system include a shortened useful life of the processing chemistry and deterioration of the image quality due to pepper spots, drag streaks, narrow screen range and high dependence on processing.

This present invention discloses an alternative method for producing high quality dot images that solves most of the problems inherent in the lith system. The method involves the use of novel hydrazide derivatives as additives to silver halide emulsions for the purpose of providing good dot quality. The mechanism by which hydrazides operate has been proposed by Okamura et al. East-West IS & Meeting 1993 and by K.I.

Shinohara et al. J. Photo. Sci. 35. 181, 1987.

The more soluble hydrazides can be incorporated into the processing solution, but if they are to be incorporated into the photographic element, their mobility is preferably reduced. This can be achieved by incorporating either a ballast group or a functionality that promotes adsorption to the silver halide grain surface. When groups such as thiourea, thioamide, heterocyclic rings, or urea are used as adsorption-promoting functionalities, the molar concentration of the hydrazide can be reduced by an order of magnitude without loss of activity. This is a significant advantage over the use of mobile hydrazines because, at the high concentrations necessary to exhibit contrast enhancement in a negative emulsion, some hydrazines release sufficient nitrogen to disrupt the ordered array of the photographic element and thereby deteriorate the image quality.Furthermore, diffusion of the mobile hydrazines into the processing chemistry alters the properties of the chemistry with time.

The selection of an adsorption-promoting substituent for a phenyl hydrazide is limited in that 'Tightly adsorbed aryl hydrazides are not usually efficient in increasing the contrast in negative-working silver halide emulsion. It is believed that contrast is increased by infectious development and that undue restriction of mobility interferes with the ability of the aryl hydrazides to promote infectious development'. Parton, U.S. Pat. No. 4,459,347. The delicate balance necessary to provide adsorptivity to the silver halide grain while still providing adequate solubility, as well as the requirement for stability and inherent acticity, place serious constraints upon the design of the new aryl hydrazide contrast-enhancing agents.

Significantly, although both the mobile hydrazides and the adsorption-promoting hydrazides substantially increase the contrast of a photographic emulsion, only a selected few of the latter class also improve dot quality. Undoubtedly, the dual constraints on controlled adsorptivity of the hydrazide and the printing parameters, which require tight control on screen range, severely limit the initially large number of choices of hydrazide derivatives that produce high contrast; it follows then that these constraints also limit the number of hydrazides that can produce high quality dots since high contrast is a necessary factor in producing high-quality dots.

US Patent No. 2,419,975 teaches that high-contrast negative photographic characteristics can be obtained by adding hydrazine compounds to photographic emulsions. The art has however long recognised that the activity of hydrazides can be increased by direct attachment of a substituted carbonyl blocking group to the remaining nitrogen.

Presently, only a few substituents attached to the acyl-carbonyl group have demonstrated utility in high contrast systems. The most common in the art are hydrogen, alkyl and aryl which can be substituted.

Particularly useful are derivatives of oxalic acid as hydrazide blocking groups..

A few recent patents teach that the most efficient hydrazides employ a combination of substituents to balance photographic performance and stability.

Some of these facts have been recognised and subsequently have become part of the state of the art. Groups promoting the adsorption to the silver halide have been described in several more recent publications, for instance in Machonkin (US 5,126,227) which discusses the necessity of incorporating ballasting groups in order to promote activity due to diffusion fastness. Likewise in Koga et al. (US 5,212,045) increased diffusion fastness is achieved by doubling their structures via divalent linkage groups. In order to achieve enhanced activity it has likewise become part of the art to combine hydrazides used as contrast promoting agents and a wide variety of amines. These amines are in general called 'boosters'.

High contrast developing compositions which contain amino compounds as 'boosters' and are intended for carrying out development in the presence of a hydrazine compound are also disclosed in U.S. Patents 4,668,605 issued May 26, 1987 and 4,740,452 issued April 26, 1988 and in Japanese Patent Publication No. 211647/87 published September 17, 1987. U.S.

Patent 4,668,605 describes developing compositions containing a dihydroxyalkyl group of 2 to 10 carbon atoms, and a mercapto compound.

The developing compositions of U.S. Patent 4,740,452 contain a contrast-promoting amount of certain trialkyl amines, monoalkyldialkanol amines or dialkylmorloalkanol amines. The developing composition of Japanese Patent Publication No 211647/87 contains a dihydroxybenzene developing agent. a sulfite and certain amino compounds characterised by reference to their partition coefficient values. However, the developing compositions of U.S. Patents 4,668,605 and 4,740,452 and Japanese Patent Publication No. 211647/87 do not fully meet the needs of the state of the art since they exhibit many disadvantages.

U.S. Patent 4,269,929 describes the use of a very wide variety of amino compounds as contrast-promoting agents for use in developer baths. In particular, it discloses the use of nines, such as hydroxylamines, 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.

The same aspect has been put forward by Looker (EP 0,458,708) where ballasted hydrazides have been described which contain the same structural elements, for instance hydrazides of the structure:

where each R is an alkyl group, preferably containing 1 to 12 carbon atoms, n is 1 to 3, X is an anion such as chloride or bromide, m is 1 to 6, Y is a divalent aromatic radical, and R1 is hydrogen or a blocking group. The divalent aromatic radical represented by Y, such as a phenylene radical or naphthalene radical, can be unsubstituted or substituted with one or more substituents such as alkyl, halogen, alkoxy, haloalkyl or alkoxyalkyl.

These hydrazides have been combined with amine boosters of well defined structures added to the coating formulation. Also Machonkin in US 5,126,227 further improves the activity of the combination of hydrazides and boosters by addition of a third compound of the structure

where R is alkyl While the inventions of EP 0,458,708 and US 5,126,227 represent very important technical progress they still suffer from the disadvantage of having to rely on 'incorporated boosters' and additional activity promoters to achieve the necessary activity.

Some of the disadvantages connected with the necessity of adding amines either to the processing chemistry or to coated film, are quite obvious.

Thus some amines suffer from the problem of toxicity, some from the problem of excessive volatility, some are characterised by highly unpleasant odours, some tend to form azeotropes with water, some exhibit an inadequate degree of solubility in an aqueous alkaline photographic 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 contrast-promoters in the method and composition of U.S. Patent 4,269,929 that is less than desired for commercial operation.

Yogihara (EP 0,286,062) introduces the concept of 'nucleation accelerators'. He describes compounds of the structure:

The combination of hydrazides and booster amines in photographic assemblies has been described as "an exceedingly complex system". It depends on many parameters like for instance the concentration of the individual elements as well as the ratio of the different hydrazide/booster combinations. Further, it might depend particularly on pH, temperature and time of photographic processing. The tight control of the system and of the processing becomes quite difficult.

There are considerable requirements imposed onto today's photographic systems and therefore also on the single components used in the design of such systems.

One of the aspects of eminent practical and commercial value of photographic assemblies of this type is the stability of unprocessed material under sometimes quite adverse conditions. Of equal importance is the reliability and constant photographic performance of the materials. These aspects are tightly connected with a simple and robust design.

From the proposed mechanism it becomes quite obvious for those skilled in the art that activity and stability of hydrazides and/or the combination of hydrazides and booster amines are difficult to balance, eg the more active a compound or a combination of compounds are the less likely a good long term stability is to be expected.

Sufficient activity and stability are often so tightly connected that they seem to be mutually exclusive. Needed are therefore on one hand hydrazide structures with improved stability when incorporated into a photographic material and on the other hand hydrazide structures optimised with respect to their activity. There is also the wish to keep the systems simple and easy to control. There exists moreover a need for photographic materials, particularly in the field of graphic arts which are functioning in processing systems with high stability under normal working conditions. It has since long been recognised that such stable processing solution, in particular developer solutions, can only be obtained if the pH of such solutions is kept as low as possible, that is in the range of 9.5 to 12.0, preferably in the range of 9.5 to 11.0.It has been reported (IS & T 46th Annual Conference 1993) that a major factor in achieving sufficient activity in hydrazide promoted photographic systems processed at a pH of 10.5 is strictly linked to hydrazide structures where the ballasting group is linked to the aromatic ring connected to the hydrazine via a sulphonamido group.

(Looker, loc.cit.) On the other hand hydrazides of the following general structure have been reported to have high activity.

for instance in US 4,686,167 (Resnick et al.) or

for instance in US 5,279,919 (Hitashi et al.) Where BC is a blocking group and R stands for a ballasting group. In other cases R stands for a group promoting the adhesion to silver halide. Such examples can for instance be found in EP,398,285, EP,397,167, US,5,006,445 and US,468,167. Often the ballasting group contains bulky organic substituents in order to control diffusion. In those cases the molecules are often difficult to dissolve in solvents which are well tolerated by photographic systems. The choice of useful solvents which can be used to make up hydrazide solutions to be added to photographic layers is quite restricted.Most of the efficient solvents for such high molecular compounds of the type described here often have harmful effects on the photographic properties of the coated layers. In addition the quantities and the properties of organic solvents allowed in industrial coating operations is quite limiting due to ecological requirements. The elimination of organic solvents is for the described reasons highly desirable, ideally hydrazides used as described here should be water soluble. To a certain extent water solubility and diffusion fastness seem to be mutually excluding properties. Diffusion fastness is however one of the prerequisites of high performance of active compounds.

Hydrazides with high activity, showing no or little diffusion during action, that is performing their action close to the silver grain, are of particular importance when the photographic material is to be used with modern electronic imagesetters using lasers to generate ultra fine dots. It is however well known that ultra high contrast photographic material alone is not sufficient to ensure smooth high quality dots in halftone photographic material. Hydrazides even when of high activity but lacking diffusion fastness tend to promote dots with ragged edges leading to unsharp images.

Summary of the invention: The chief object of the present invention is to provide novel water soluble contrast-enhancing agents that can be used in photographic elements to produce high-contrast negative images.

Another object of the present invention is to provide water soluble hydrazides acting as contrast enhancing agents providing sufficient activity without requiring a booster amine.

A third object of the present invention is to provide water soluble hydrazides which, besides demonstrating sufficient activity exhibit excellent long-term stability when incorporated into photographic assemblies.

A fourth object of the present invention is to produce a photographic element that can be processed in a stable developer of a pH < 11 and still yield a high contrast material.

Therefore according to the present invention there is provided a hydrazide compound of the general formula 1:

wherein U is an unsubstituted or substituted alkylene or arylene group with up to 8 carbon atoms, n and m are 1 or 0 and may be equal or different, RI and R2 are independently an alkyl or isoalkyl group containing 1-4 carbon atoms, a substituted alkyl, an alkoxy or aralkoxy group with up to 12 carbon atoms, or halogen and where either R1 or R2 can also be hydrogen, or RI and R2 together can form an aromatic or a partially unsaturated ring, R3 is H or alkyl with up to 4 carbon atoms, is is an activity regulating group, and G is an anion.

By activity regulating group is a group by virtue of its electronic deficiency is capable of increasing the activity of adjacent hydrogen atoms. Preferred compounds of formula I are those wherein A+ is selected from

where Z denotes the atoms necessary to form an unsaturated, partially unsaturated or a fused heterocyclic ring, R4, R5, R6 and R7, R8 Rg are 9 each equal or different and selected from the group alkyl or isoalkyl Cl-C8, substituted alkyl, aralkyl, phenyl and substituted phenyl, R5 and R6 can be linked to form a heterocyclic ring, R8 and Rg can be linked to form a heterocyclic ring, and G is an anion.

Particularly preferred activity regulating groups A+ of formulae I, II, or III and as set forth above are those wherein Z denotes the unsubstituted or substituted elements necessary to form an aromatic five or six membered heterocyclic ring, R4, R5, R6 are each equal or different and selected from the groups alkyl. alkoxy, hydroxy, thioalkyl or substituted alkyl C2 - C4, R5 and R6 can be linked to form a preferentially five or six membered ring, R7, R8 Rg are phenyl, tolyl or alkyl C2 - C4 and in such cases preferably U is ethylene or propylene, 2-hydroxypropylene, n and m are 1 or 0 and G is chloride or bromide.

When the activity regulating group of formula I is a triazolium residue the following triazoles can be used to form the residue.

When the activity regulating group of formula I is an imidazolium residue the following imidazoles can be used to form the residue:

The preferred imidazoles are:

When the activity regulating group of formula I is a pyridinium residue the following pyridines can be used to form the residue:

The preferred pyridines are:

When the activity regulating group is of formula II and R4, R5 and R6 are each the same alkyl. It may be trimethylammonium up to trioctylammonium, preferentially triethylammonium to tributylammonium.

When R5 and R6 are linked it may be N-methylpiperidinium up to N-butylpiperidinium, N-hdroxyethylpiperidinium, N-methoxyethyl - piperidinium, preferentially it is N-butylpiperidinium; or it may be N.methyl morpholinium up to N-butylimorpholinium, N-hydroxyethylmorpholinium, N-methoxyethylrnorpholinium; preferentially it is N-butylmorpholinium; or it may be N-methylpyrrolidinium up to N-butylpyrrolidinium, N-hydroxyethyl- pyrrolidinium, N-methoxyethyl pyrolidinium, preferentially it is N-butylpyrrolidinium; With reference to the compound of formula 1 usefully R1 and R2 are independently H, alkyl or substituted alkyl C1-C4, hydroxyalkoxy, an alkoxy group with up to 4 carbon atoms, a group or halogen with the provision that at least RI or R2 are different from H.

Alternatively R1 and R2 together can form an aromatic, or a partially unsaturated ring with up to six atoms.

R3 is hydrogen or alkyl with 1-4 carbons. Preferentially R3 is hydrogen.

Most preferably R1 and R2 are methyl ethyl methyloxy or ethoxy and R1 or R2 can be H.

In formula 1 G is mesylate, tosylate, bromide or chloride.

Preferentially G is chloride.

Useful compounds of formula 1 are those wherein n and m are each 0 and U is -(CH2)2-.

Other useful compounds are those wherein n and m are each 0 and U is

Another useful group of compounds are those wherein n and m are each 1 and U is -CH2CH2-OH.

Yet another useful group of compounds are those wherein n and m are both 0 and

wherein R20 is C1 to C4 alkyl.

Preferred compounds of formula 1 are compounds of the general structure 2:

where R1, R2, R3, U and A are as defined with reference to the compounds of formula 1.

Particularly preferred compounds of formula 1 are compounds of formula 3:

and of formula 4:

where in the above two formulae R1-R3 are as defined with reference to formula 1 R10 is alkyl, isoalkyl, dimethylamino, pyrolidino, acylamino, sulphonylamino, R11 and R14 are H or methyl, Rl2 is alkyl or substituted alkyl, R13 is H or methyl, U is ethylene, propylene, phenylene or substituted phenylene, Water solubility is a function of four structural elements in compounds of formula 1 which includes:1. at least one hydroxy group in the end group of the oxalylamino group.

2. at least one substituent R1 or R2 which is not hydrogen, 3. a cationic activity regulating group A+ and 4. a negatively charged counter ion G Synthesis of Compound 1.01

ntermediote A intermediate B

0 oc a-cH,-e-HN - NH- C- C- NHCYCYOH CH3 ínterrnedste C &verbar; H3C < | H3C V CH,- 0 0 0 N \,N-C- - C - NH vNH- NH- C-C- NHCeCH20H Cl CHn Compound 1.01 Example 1.01 Intermediate A: The mixture of 267g 2-ethoxalyl-l-(2-methyl-4- nitrophenyl) hydrazine and 73g of ethanolamine was heated up in 2500 ml ethanol on a steam bath for 1.5 hours.After cooling, the yellowish precipitate was filtered, washed with ethanol and dried. Yield: 246g; Melting point: 199-204C (dec.) Intermediate B: A mixture of 141.lg of intermediate A, 700ml of dimethylacetamide and 108 Pd/C catalyst was hydrogenated at 50 psi over a 20 hour period to obtain intermediate B. Then the catalyst is filtered off and the solution was diluted with the same volume of water.

On cooling in an ice bath the product precipitated in yellowish needles.

Yield: 102.2g; Melting point: 198-202"C.

Intermediate C: A solution of 25.2g of intermediate B and 14.2g of ethyl-N,N-disopropylamine in 150 ml of dry dimethylacetamide was cooled in an ice bath. 11.3g of chloroacetyl chloride was added over a 30 minute period at 0-5"C. The reaction mixture was stirred at room temperature for 2 hours and then it was poured into 300g of ice water; the separated solid was filtered off, washed well with water and dried.

The product was a nearly colourless soli, 28.2g, Melting point: 191-194"C.

Compound 1.01: A solution of 3.3g intermediate C and 1.5g of 4-dimethylaminopyridine in 15ml of dry dimethylacetamide was heated up to 80"C. After 3 hours 10ml of isopropanol was added and the reaction mixture was allowed to cool. The colourless product was filtered, washed with isopropanol and dried to give 3.6g.

The structure agrees with the expected nmr spectrum.

Compound 1.13: A solution of 6.4 g intermediote C and 2.4 g of triethylomine in 25 ml of dry dimethylacetamide was heated up to 80' C. After 3 hours 20 ml of isopropanol was added ond the reaction mixture was allowed to cool. The colorless product was filtered, washed with isopropanol ond dried to give 5.1 g.

The structure agrees with the expected nmr spectrum.

Example 1.05 Compound 1.05: A solution of 3.3g intermediate C and 2.9g of triphenylphosphine in l5ml of dry dimethylacetamide was heated up to 100"C. After 6 hours the reaction mixture was cooled and poured into 10Oml of isopropanol. the yellowish product was filtered off, washed with isopropanol and dried to give 4.4g.

The structure agrees with the expected nmr spectrum.

Table 1

The amount of the compound of formula (1) added to the silver halide emulsion layer or hydrophilic colloidal layer(s) is such that the compound does not appreciably function as a developer. Typically, -8 -2 5 x 10-2 moles/mole -5 amounts from 10 to 5 x 10 moles/mole Ag and preferably about 10 to 5 x 10 moles/mole Ag are used.

The compound can be incorporated in a silver halide emulsion used in the photographic element. Alternatively, the hydrazide 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 compound are desired. The compound of the present invention can, of course, be present in the photographic element distributed between or among the emulsion and hydrophilic colloid layers, such as undercoating layers and overcoating layers.

The hydrazide compounds of the present invention are employed in combination with negative-working photographic emulsions comprising radiation-sensitive silver halide grains capable of forming a surface latent image, and a binder. The silver halide emulsions include the high-chloride emulsions conventionally employed in forming lith photographic elements as well as silver bromide and silver bromiodide emulsions, which are recognised 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 the total amount of silver halide.

The compound of formula 1 can be incorporated in the photographic element by common techniques used for the addition of additives to photographic emulsions. The compound are typically dissolved in a solvent selected from water or organic solvents compatible with water such as alcohols, glycols, ketones, esters, amides, and the like which exert no adverse influences on the photographic characteristics, and the solution is added to the photographic element. The preferred solvent is water. Ultrasound can be employed to dissolve marginally soluble hydrazides.

Still another way to introduce compounds of formula 1 is in the form of fine dispersions loaded onto latex particles. Suitable latices are the same as described below. Hydrazides which are less soluble in water can be introduced as their water-soluble cyclodextrine complexes. The preferred way however for the claimed hydrazides is their introduction as aqueous solutions.

These solutions or dispersions can be added to the emulsion at any stage subsequent to the precipitation and washing steps. Preferably, these agents should be added just prior to coating.

Gelatin is advantageously used as a binder or protective colloid in the photographic emulsion, but other hydrophilic colloids can also be used.

For example, gelatin derivatives, graft polymers of gelatin with other high molecular weight materials, proteins such as albumin or casein.

Cellulose derivatives such as hydroxyethyl cellulose, carboxymethyl cellulose or cellulose sulfate, saccharide derivatives such as sodium alginate or starch derivatives, various synthetic hydrophilic high molecular weight materials such as homopolymers or copolymers, e.g., polyvinyl alcohol, poly-N-vinyl pyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyvinyl imidazole, polyvinyl pyrazole or polyurethane can be added as hydrophilic colloids.

Preferred are homo-, Co- or terpolymers in form of latices of small particle size distribution.

Examples of suitable gelatin graft polymers include those prepared by grafting a homopolymer or a copolymer of a vinylic monomer such as acrylic acid, methacrylic acid, the derivatives thereof (such as the esters or the amides thereof), acrylonitrile or styrene to gelatin. In particular, graft polymers prepared from polymers which are compatible with gelatin to some degree, such as those of acrylic acid, methacrylamide or a hydroxyalkyl methacrylate are preferred. Examples of those polymers are described in, e.g., U.S. Pat. Nos. 2,763,625, 2,831,767 and 2,956,884, etc. Typical synthetic hydrophilic high molecular weight materials are described in, e.g., German Patent Application (OLS) 2,312,708, U.S. Pat. Nos. 3,620,751, and 3,879,205, all incorporated by reference.

In forming photographic elements the layers can be coated on photographic supports by various procedures, including immersion or dip coating, roller coating, reverse roll coating, doctor blade coating, gravure coating, spray coating, extrusion coating, bead coating, stretch-flow coating and curtain coating. High speed coating using a pressure differential is illustrated by U.S. Patent No. 2,681,294.

The layers of the photographic elements can be coated on a variety of supports. Typical photographic supports include polymeric film provided with one or more layers to enhance the adhesive, antistatic, dimensional, abrasive, hardness, frictional, antihalation and/or other properties of the support surface.

Typical of useful polymeric film supports are polyester films and films of cellulose nitrate and cellulose esters such as cellulose triacetate and diacetate, polystyrene, polyamines, homo- and co-polymers of vinyl chloride, poly(vinyl acetal), polyolefin, particularly a polymer of an olefin containing 2 to 10 carbon atoms, such as polyethylene, polypropylene, copolymers of ethylene and propylene and the like.

Polyolefins, such as polyethylene, polypropylene and copolymers of ethylene with propylene, as illustrated by U.S. Patent No. 4,478,128, are preferably employed as resin coatings over paper, as illustrated by U.S. Patent Nos. 3,411,908 and 3,630,740, over polystyrene and polyester film supports, as illustrated by U.S. Patent No. 3,973,963.

Preferred cellulose ester supports are cellulose triacetate supports, as illustrated by U.S. Patent Nos. 2,492,977; 2,492,978 and 2,739,069, as well as mixed cellulose ester supports, such as cellulose acetate propionate and cellulose acetate butyrate, as illustrated by U.S. Patent No. 2,739,070.

Preferred polyester film supports are comprised of linear polyester, such as illustrated by U.S. Patent Nos. 2,627,088; 2,720,503; 2,779,684 and 2,901,466.

The photographic emulsion used in this invention can be prepared using the well-known methods described in, e.g., P. Glafkides, Chimie et Physique Photographique, Paul Montel, Paris (1967), G. F. Duffin, Photographic Emulsion Chemistry, The Focal Press, London (1966).

V. L. Zelikman et al., Making and Coating Photographic Emulsions, the Focal Press, London (1964), all incorporated by reference. These methods include the acid method, the neutral method, the ammonia method and others. Moreover, a soluble silver salt can be reacted with a soluble halogen salt using any of the single jet method, the double jet method and a combination thereof. The method of forming grains in the presence of an excess of silver ions (the so-called 'reverse mixing method') can also be used. The 'controlled double jet method' (also called 'controlled diffusion method') is preferred. According to this method, the pAg of the liquid phase (in which the silver halide is to be produced) is kept constant or varied systematically to provide emulsions with the desired properties.This method can provide silver halide emulsions having a regular crystal form and an almost uniform grain size.

The silver halide grains in the photographic emulsion used in this invention can have a relatively wide grain size distribution, but a narrow grain size distribution is preferred. In particular, the size of the silver halide grains amounting to 90% of the total, based on the weight or number of the grains, is preferably within + 40% of the average grain size (such an emulsion is usually called a monodispersed emulsion).

The individual reactants can be added to the reaction vessel through surface or sub-surface delivery tubes by gravity feed or by delivery apparatus for maintaining control of the pH and/or pAg of the reaction vessel contents, as illustrated by Culhane et al (U.S.Patent 3,821,002), and Oliver (U.S. Patent 3,031,304), all incorporated by reference. In order to obtain rapid distribution of the reactants within the reaction vessel, specially constructed mixing devices can be employed, as illustrated by Audran (U.S. Patent 2,996,287), McCrossen et al (U.S. Patent 3,342,605), Frame et al (U.S. Patent 3,415,650), Porter et al (U.S. Patent 3,785,777), Saito et al (German OLS 2,556,885) and Sato et al (German OLS 2,555,364), all incorporated by reaction vessel, as illustrated by Forster et al U.S. Patent 3,897,935 and Posse et al U.S.

Patent 3,790,386.

The grain size distribution of the silver halide emulsions can be controlled by silver halide grain separation techniques or by blending silver halide emulsions of differing grain sizes. The emulsions can include ammoniacal emulsions, as illustrated by Glafkides, Photographic Chemistry, Vol. 1, Fountain Press, London, 1958, pp. 365-368 and pp.

301-304; thiocyanate ripened emulsions, as illustrated by Illingsworth (U.S. Patent 3,320,069); thioether ripened emulsions, as illustrated by McBride (U.S. Patent 3,271,157), Jones (U.S. Patent 3,574,628) and Rosecrants et al (U.S. Patent 3,737,313) or emulsions containing weak silver halide solvents, such as ammonium salts, as illustrated by Perignon (U.S. Patent 3,784,381) and Research Disclosure, Vol. 134, June 1975, Item 13452, all incorporated by reference.

The crystal form of the silver halide grains in the photographic emulsion may be regular (such as cubic or octahedral) or irregular (such as spherical or plate-like) or a composite of these forms. The grains may comprise mixed grains having various crystal forms.

The interior and the surface layer of the silver halide grains may be different or the grains may be uniform throughout. During formation or physical ripening of the grains, cadmium salts, zinc salts, lead salts, thallium salts, iridium, cobalt, rhodium salts or complex salts thereof, iron salts or iron complex salts, and the like can be present, as can mixtures thereof. Preferred are rhodium or iridium salts or mixtures thereof.

Two or more of silver halide emulsions which are separately prepared can be mixed and then used, if desired, After the formation of the precipitates or after physical ripening, the soluble salts are usually removed from the emulsion. For this purpose ultrafiltration or the well-known noodle washing method may be used.

Alternatively, the flocculation method may be used. This method employes an inorganic salt having a polyvalent anion such as sodium sulfate, an anionic surface active agent, an anionic polymer (such as polystyrene sulfonic acid) or a gelatin derivative (such as an aliphatic acylated gelatin, an aromatic acylated gelatin or an aromatic carbamoylated gelatin). The removal of the soluble salts may be omitted, if desired.

Although the silver halide emulsions used in the present invention do not need to be chemically sensitised, chemically sensitised silver halide emulsions are preferred. Processes for chemical sensitisation, of silver halide emulsions which can be used include known sulfur sensitisation, reduction sensitisation and noble metal sensitisation processes. In addition to sulfur sensitisation, selenium, tellurium, rhenium or phosphorus sensitisers or combinations of these sensitisers can be used. Chemical sensitisation can be performed at pAg levels of from 5 to 10, pH levels of from 5 to 8 and at temperatures from 30 to 80'C.

These processes are described in references such as P. Glafkides, Chimie et Physique Photographique, Paul Montel, Paris (1967) or Zelikmann, Making and Coating Photographic Emulsions, The Focal Press, London (1964) or H. Frieser, Die Gundlagen der Photographischen Prozesse mit Silberhalogeniden, Akademische Verlagsgesellschaft (1968). The disclosures of these references are incorporated by reference. In the noble metal sensitisation processes, a gold sensitisation process is a typical process where gold compounds or mainly gold complexes are used.

Complexes of noble group VIII metals other than gold, such as those of platinum, palladium, osmium or iridium, etc. can also be used. A reduction sensitisation process may be used if the process does not generate fog to a degree that causes practical difficulties. A particularly preferred chemical sensitisation process for the present invention is the use of a sulfur sensitisation process.

Examples of sulfur sensitising agents which can be used include not only sulfur compounds present in the gelatin per se, but also various sulfur compounds for example thiosulfates, thioureas, thiazoles or rhodanines.

Examples of suitable sulfur compounds are described in U.S. Pat. Nos.

1,574,994, 2,410,689, 2,278,947, 2,728,668 and 3,656,955, all incorporated by reference. Typical examples of suitable reduction-sensitising agents include stannous salts, amines, formamidine sulfinic acid and silane compounds, methyldichlorosilane, hydrazine derivatives, aminoboranes, thiourea dioxide, hydrogen, cyanoborohydrides, etc. Reduction sensitisation can also be obtained by low pAg (less than 5) or high pH (greater than 8) treatment.

Specifically contemplated is the combined use of several of the aforementioned chemical ripening techniques; in particular, gold-sulfur combinations are highly preferred.

A photographic material used in this invention may contain an anti-foggant. Examples of anti-foggants which can be advantageously used for the photographic material used in this invention are 1, 2, 4-triazole compounds substituted with a mercapto group at the 3-position, benzotriazole compounds, 2-mercaptobenzimidazole compounds (which do not contain a nitro group), 2-mercaptopyrimidines, 2-mercaptothiazoles, 2-mercaptobenzothiazoles, benzothiazolium compounds (such as N-alkylbenzothiazolium halides, nitrobenzindazole, substituted triazaindolizines (tetraazaindenes) or N-allylbenzothiazolium halides), 2-mercapto-l, 3,4-thiazoles and aromatic thiosulphides. Antifoggants which are not effective when used alone, such as 6-nitrobenzimidazole, however, can be used in combination with any of the above advantageous antifoggants.

It has been observed that both fog reduction and an increase in contrast are obtainable by employing benzotriazole antifoggants. When the benzotriazole is located in the photographic element concentrations of -4 -l -3 -2 10 4 to 10 , preferably 10 to 3 x 10 mole per mole of silver are employed.

Useful benzotriazoles can be chosen from among conventional benzotriazole antifoggants, such as those disclosed by Land (U.S. Patent 2,704,721) and Rogers et al (U.S. Patent 3,265,498), both incorporated by reference. The preferred benzotriazoles for use in this invention are benzotriazole (that is, the unsubstituted benzotriazole compound), halo-substituted benzotriazoles (e.g., 5-chlorobenzotriazole, 4-bromobenzotriazole and 4-chlorobenzotriazole) and alkyl-substituted benzotriazoles wherein the alkyl moiety contains from about 1 to 12 carbon atoms (e.g., 5-methylbenzotriazole). 5-methyl benzotriazole is most preferred. The use of 5-methylbenzotriazole as an antifoggant is illustrated by Baldassari et al (U.S. Patent 3,925,086), incorporated by reference.

The photographic emulsions used in this invention can be spectrally sensitised with methine or other dyes. Suitable sensitising dyes include cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes, holopolar cyanine dyes, hemicyanine dyes, styryl dyes and hemioxonol dyes. Particularly useful dyes are cyanine dyes, merocyanine dyes and complex merocyanine dyes.These dyes can contain, as a basic heterocyclic nucleus, any of the nuclei which are usually employed in cyanine dyes: a pyrroline nucleus, an oxazoline nucleus, any of the nuclei which are usually employed in cyanine dyes: a pyrroline nucleus, an oxazoline nucleus, a thiazoline nucleus, a pyrrole nucleus, an oxazole nucleus, a thiazole nucleus, a selenazole nucleus, an imidazole nucleus, a tetrazole nucleus, a pyridine nucleus and the like; one of the above-described nuclei condensed with an alicyclic hydrocarbon ring; and one of the above-described nuclei condensed with an aromatic hydrocarbon ring, such as an indolenine nucleus, a benzindoleinine nucleus, an indole nucleus, a benzoxazole nucleus, a naphthoxazole nucleus, a benzothiazole nucleus, a naphthothiazole nucleus, a benzoselenazole nucleus, a benzimidazole nucleus and a quinoline nucleus. The carbon atoms of the above-described nuclei may be substituted.

The merocyanine dyes or complex merocyanine dyes can contain, as a nucleus having a ketomethylene structure, a 5-to 6-membered heterocyclic nucleus such as a pyrazolin-5-one nucleus, a thiohydantoin nucleus, a 2-thiooxazolidin-2,4-dione nucleus, a thiazolidin-2, 4-dione nucleus, a rhodanine nucleus or a thiobarbituric acid nucleus.

Useful sensitising dyes are those described in, e.g., German Pat. No.

929,080, U.S. Pat. Nos. 2,231,658, 2,493,748, 2,503,776, 2,519,001, 2,912,329, 3,656,959, 3,672,897, and 3,694,217, and British Pat. No.

1,242,588, all incorporated by reference.

These sensitising dyes may be used individually or in combination. A combination of sensitising dyes is often employed particularly for the purpose of supersensitisation. Typical examples of such combinations are described in, e.g., US. Pat. Nos. 2,688,545, 2,977,229, 3,397,060, 3,522,052, 3,527,641, 3,617,293, 3,628,964, 3,666,480, 3,679,428, 3,703,377, 3,769,301, 3,814,609 and 3,827,862, and British Pat. No.

1,344,281, all incorporated by reference. Preferred sensitising dye combinations are mixtures of cyanine and merocyanine dyes that orthochromatically sensitise at wavelengths between 400 and 580nm.

The sensitising dyes may be present in the emulsion together with dyes which themselves do not have any spectral sensitising effects but exhibit a supersensitising effect when used in combination, or with materials which do not substantially absorb visible light but exhibit a supersensitising effect when used in combination. For example, aminostilbene compounds substituted with a nitrogen-containing heterocyclic ring group (e.g., those described in U.S. Pat. Nos.

2,933,390 and 3,635,721), aromatic organic acid formaldehyde condensates (e.g., those described in U.S. Pat. No. 3,743,510), azaindene compounds, and the like, can be present. The combinations described in U.S. Pat.

Nos. 3,615,613, 3,615,641, 3,617,295 and 3,635,721 are particularly useful. (The disclosure of all patents mentioned in this paragraph is incorporated by reference).

Other sensitising dyes which may be used are those which exhibit maximum sensitivity at the peak emission of some lasers such as 488nm for the argon laser, 633nm for the HeNe laser, 650-680nm for the Red LED laser and 760-820 for the infra-red diode laser.

A water-soluble dye may be present in any of the hydrophilic colloid layers of the photographic light-sensitive material used in this invention, for example, as a filter dye or for prevention of light scattering, or for antihalation. Examples of these dyes include oxonol dyes, hemioxonol dyes, styryl dyes, merocyanine dyes, cyanine dyes and azo dyes. Of these dyes, oxonol dyes, hemioxonol dyes and merocyanine dyes are particularly useful. Specific examples of dyes which can be used are those described in British Pat. Nos. 584,609 and 1,177,429, and U.S. Pat. Nos. 2,274,782, 2,533,472, 2,956,879, 3,148,187, 3,177,078, 3,247,127, 3,540,887, 3,575,704, 3,653,905 and 3,718,472, all incorporated by reference.

A hardener may be present in any of the hydrophilic colloid layers in the light-sensitive material used in this invention. These hardeners include, for example, chromium salts (such as chrome alum or chromium acetate), aldehydes (such as formaldehyde, glyoxal or glutaraldehyde), N-methylol compounds (such as dimethylolurea or methyloldimethylhydantoin), dioxane derivatives (such as 2,3-dihydroxydioxane), active vinyl compounds (such as 1,3, 5.triacrylolyl.hexahydro-s-triazine), mucohalic acids (such as mucochloric acid or mucophenoxychloric acid), isooxazoles, dialdehyde starch, dichlorohydroxytriazine and carbamoyl-pyridinium compounds can be used alone or in combination.

Specific examples of these compounds are described, e.g., U.S. Pat. Nos.

1,870,354, 2,080,019, 2,726,162, 2,870,013, 2,983,611, 2,992,109, 3,047,394, 3,057,723, 3,103,437, 3,321,313, 3,325,287, 3,362,827, 3,539,664 and 3,543,292, British Pat. Nos. 676,628, 825,544 and 1,270,578, and German Pat. Nos. 872,153 and 1,090,427, all incorporated by reference.

Examples of preferred hardeners are dichlorohydroxytriazine or 2 - (4-dimethylcarbamoyl-pyridino) ethane sulfonate.

The light-sensitive material of this invention may contain various known surface active agents for various purposes, e.g., as a coating aid, for preventing the generation of static charges, improving slip characteristics, improving emulsion dispersion, preventing adhesion, improving photographic characteristics (e.g., accelerating development, increasing contrast, sensitisation), etc.

Examples of suitable surfactants are: nonionic surface active agents such as saponin (steroids), alkylene oxide derivatives (such as polyethylene glycol, polyethylene glycol/polypropylene glycol condensates, polyethylene glycol alkyl or alkylaryl ethers, polyethylene glycol esters, polyethylene glycol sorbitan esters, polyalkylene glycol alkylamines or amides or silicont/polyethylene oxide adducts), glycidol derivatives (such as alkenylsuccinic acid polyglycerides or alkylphenol polyglycerides), aliphatic esters of polyhydric alcohols, alkyl esters of sucrose, urethanes or ethers; anionic surface active agents containing an acidic group such as a carboxy group, a sulfo group, a phospho group, a sulfuric acid ester group of a phosphoric acid ester group, such as triterpenoid type saponin, alkylcarboxylates, alkylsulfonates, alkylbenzenesulfonates, alkylnaphthalenesulfonates, alkyl sulfuric acid esters alkyl phosphoric acid esters, N-acyl-N-alkyltaurines, sulfosuccinates, sulfoalkylpolyoxyethylene alkylphenyl ethers or polyoxyethylene alkylphosphates; amphoteric surface active agents such as amino acids, aminoalkylsulfonic acids, aminoalkylsulfonic acid esters, aminoalkylphosphoric acid esters, alkylbetaines, amineimides or amine oxides; and cationic surface active agents such as alkylamine salts, aliphatic or aromatic quaternary ammonium salts, (such as pyridinium or imidazolium salts) or phosphonium or sulfonium salts containing an aliphatic or heterocyclic ring.

Specific examples of these surface active agents are those described in, e.g., U.S. Pat. Nos. 2,240,472, 2,831,766, 3,158,484, 3,210,191, 3,294,540 and 3,507,660, British Pat. Nos. 1,012,495, 1,022,878, 1,179,290 and 1,198,450, U.S. Pat. Nos. 2,739,891, 2,823,123, 3,068,101, 3,415,649, 3,666,478 and 3,756,828, British Pat. No. 1,397,218, U.S.

Pat. Nos. 3,133,816, 3,441,413, 3,475,174, 3,545,974, 3,726,683 and 3,843,368. Belgium Pat. No. 731,126, British Pat. Nos. 1,138,514, 1,159,825 and 1,374,780, and U.S. Pat. Nos. 2,271,623, 2,288,226, 2,944,900, 3,253,919, 3,671,247, 3,772,021, 3,589,906 and 3,754,924, all incorporated by reference. Specifically preferred is a mixture of saponin, nonionic surfactants such as aliphatic esters of polyhydric alcohols, and an anionic surfactant containing a sulfuric acid ester group.

The photographic emulsion layer and other layers can contain a dispersion of a synthetic polymer which is insoluble or slightly soluble in water for the purpose of improving the dimensional stability, the development and the fixing and drying rates. Examples of polymers which can be used include polymers composed of one or more alkyl acrylates or methacrylates, acetacetoxy acrylates and acetacetoxymethacrylates, alkoxyalkyl acrylates or methacrylates, glycidyl acrylates or methacrylates, acryl or methacrylamide, vinyl esters (for example, vinyl acetate), acrylonitrile, olefins and styrene, etc., and polymers comprising a combination of the above described monomers and acrylic acid, methacrylic acid, unsaturated dicarboxylic acids, hydroxyalkyl acrylates or methacrylates, or styrenesulfonic acid, etc. For example, those compounds described in U.S. Pat.Nos. 2,376,005, 2,739,137, 2,853,457, 3,062,674, 3,411,911, 3,488,708, 3,525,620, 3,607,290, 3,635,715 and 3,645,740, and British Pat. Nos. 1,186,699 and 1,307,373, all incorporated by reference, can be used. A suitable amount of the polymer ranges from about 10 to 80% by weight based on the total weight of the binders. Since high-contrast emulsions such as that used in this invention are suitable for the reproduction of line drawings and the dimensional stability is of importance for such a purpose, it is preferred to use the above described polymer dispersion.

In addition to the components of the photographic emulsions and other hydrophilic colloid layers described above, it is appreciated that other conventional agents compatible with obtaining relatively high contrast images can be present. For example, the photographic elements can contain developing agents (described below in connection with the processing steps), development modifiers, plasticisers and lubricants, coating aids, antistatic materials, matting agents, brighteners and colour materials, these conventional materials being illustrated in Paragraphs V, VIII, XI, XII, and XVI of Research Disclosure, December 1978 Item 17643, all incorporated by reference. Preferably, the photographic emulsion also contains antiageing agents, useful to prolong the shelf life of the emulsion.Suitable anti-ageing agents (especially for rhodium-doped emulsions) include polyhydroxyspiro-bis-indane as disclosed in U.S. Patent No. 4,346,167 of E. Imatomi and preferably a pyrazolone (up to 2g/kg of emulsion) as disclosed in U.S. Patent No.

2,751,297 of G. Hood.

The photographic elements can be imagewise exposed with various forms of energy, which encompass the ultraviolet, visible (e.g., actinic) and infrared regions of the electromagnetic spectrum as well as electron beam and beta radiation, gamma ray, X-ray, alpha particle, neutron radiation and other forms of corpuscular and wavelike radiant energy in either noncoherent (random phase) forms or coherent (in-phase) forms, as produced by lasers. Exposures can be monochromatic, orthochromatic or panchromatic.Imagewise exposures at ambient, elevated or reduced temperatures and/or pressures, including high or low intensity exposures, continuous or intermittent exposures, exposure times ranging from minutes to relatively short durations in the millisecond to nanosecond range and solarising exposures, can be employed within the useful response ranges determined by conventional sensitometric techniques, as illustrated by T.H. James, The Theory of the Photographic Process, 4th Ed., Macmillan, 1977, Chapters 4, 6, 17, 18 and 23 incorporated by reference.

The photographic light-sensitive material of this invention can be photographically processed using known methods and known processing solutions. The processing temperature usually ranges from about 18 to about 50"C, but temperatures lower than about 18"C or higher than about 50"C may be used. This invention is useful for the formation of an image by development in which a silver image is formed (a black-and-white photographic processing).

The developers used for black-and-white photographic processing preferably contain, as a developing agent, aminophenols (such as N-methyl-p-aminophenol), 3-pyrazolidones (such as l-phenyl-3pyrazolidone), dihydroxybenzene (such as hydroquinone) and other of the aforementioned developing agents. Specific examples of the useful developing agents include hydroquinone alone, hydroquinone plus N-methyl-p-aminophenol, hydroquinone plus l-phenyl-3-pyrazolidone, and hydroquinone plus N-methyl-p-aminophenyl plus l-phenyl-3 -pyrazolidone.

Also developing agents such as reductones and ascorbates usually together with an auxiliary developing agent of the l-phenyl-3pyrazolidone type may be used. Moreover, the developers usually contain an antioxidant, an alkali agent, a pH buffer or the like and, if desired, a dissolving aid, a colour toning agent, a development accelerator, a surface active agent, an anti-foaming agent, a water softener, a hardener, a tackifier, etc. An anti-fogging agent (such as an alkali metal halide or benzotriazole) may be present in the developer - According to this invention, even when development is carried out using a developer containing more than about 0.15 mol/l of sulfite ions, a gamma of more than 8 can be obtained. The pH of the developer is preferably between 10.0 and 11.5 and preferably 10-11.If the pH exceeds about 12.3, the developer is unstable even when a high concentration of sulfite ions is present, and it is difficult to maintain stable photographic characteristics for more than 3 days under normal use conditions.

Fixing solutions having a composition generally employed in the art can be used in the present invention. Not only thiosulfates and thiocyanates but also organic sulfur compounds known as fixing agents can be used as fixing agents in the present invention Preferred examples of fixing agents which can be used in the fixing solution include water-soluble thiosulfates such as sodium thiosulfate, potassium thiosulfate, ammonium thiosulfate, etc., water-soluble thiocyanates such as sodium thiocyanate, potassium thiocyanate, ammonium thiocyanate, etc., water-soluble organic diol fixing agents containing an oxygen atom or a sulfur atom such as 3-thiol,5-pentanediol, 3,6-dithiol, 8-octanediol, 9-oxo-3,6,12,15-tetrathiol, 17-heptadecanediol, etc., water soluble sulfur-containing organic dibasic acids and water-soluble salts thereof such as ethylenebisthioglycollic acid and the sodium salt thereof, etc., imidazolidinethiones such as methylimidazolidinethione, etc. These agents have been described in L.F.A. Mason, Photographic Processing Chemistry, pages 187 and 188, Focal Press (1966).

The accompanying Example will serve to illustrate the invention.

Example A gelatino-(silver chlorobromide) emulsion containing approximately 70 percent chloride and 30 percent bromide was prepared at 40"C for 42 minutes by a standard double jet addition technique producing silver halide grains having an average size of 0.28 micron with a size distribution of 12%. A Rhodium doped shell was incorporated during growth of the cubic shaped crystals. After removal of soluble salts by a conventional method, the emulsion was chemically ripened using labile sulfur compounds in addition with gold compounds at 60-C for 40 minutes.

This emulsion contained gelatin in the amount of 54g per mole of silver halide.

The concentrated developer solution was prepared from the following elements as described below: KOH (45% sol) 8ml EDTA l.Og Diethylenetriamine-pentacetic acid penta sodium salt 1.Sg Sodium bromide 4.0g Boric acid 2.5g l-Phenyl-5-mercapto-tetrazol 0.025g Benztriazol 0.250g Sodiumsulfite 55.0g Potassium carbonate 22.0g Hydroquinone 24.0g l-Phenyl-4-hydroxymethyl-4-methyl-3.pyrazolidon 0.75g Diethyleneglycol 22.0g Water to 1L The developing solutions had a pH of 10.2 to 10.75. The above concentrate is diluted with two equal parts of water to obtain a working solution. The added amount of the hydrazide was 0.75 m Mol/mol Ag.

After development the material was fixed with a conventional fixing solution, washed with water and dried.

In the examples that follow, a comparison is made between several of the preferred agents as described in the present invention and two structurally analogous agents. Significant parameters for comparison include: a) Dmin - background fog optical density b) Toe Speed - relative LogE value at OD 0.1 + fog c) Mid Speed - relative LogE value at OD 2.5 + fog d) Dmax - maximum optical density e) Gamma - (2.4 x 100) - (mid speed - toe speed) f) Dot Quality - determined for 50% dot, arbitrary scale from 1 (best to 5 (worst). Dot quality 1 and 2 are useable, dot quality 4 and 5 are not useable.

The emulsion was split into 250g portions. Each portion was identically prepared for coating by addition of the surfactant (Olin lOG) and by adjusting the gelatine such that the final coating had 5.6g silver and 3.36g gelatine/m. To the final coating solution the hydrazides to be tested were added as aqueous solutions in the amounts (moles/mole silver) indicated in the tables below. The final coating-solutions were then coated onto a subbed polyester film on a laboratory-size cascade-coater together with a protecting layer of 1.5g gelatine/m.

The system was hardened with hydroxy-dichloro-1,3,5-triazine. Results are shown in Table 2.1. 2.2, 2.3 and 2.4.

The compounds of this invention were compared with known compounds of the following structure.

Compound D from US 5.229,919 The emulsion was exposed through an optical wedge using tungsten light with 10,000 lux/sec.

The exposed material was processed in table-top processor at 35oC for 20, 30, and 40 sec/developer and 35 sec fix and wash.

The results are presented in table 2.1, 2.2 and 2.3.

They show that the examples embodying the compounds of the present invention had high Dmax, low Dmin and extremely good dot qualities when compared to examples A, B, C and D.

Table 2.1 Standard development

Dmin Dmax Gamma Dot quality T/M Emulsion 0.41 6.010 5.67 1 B 0.37 5.830 5.23 1 C 0.37 5.860 6.11 D 0.04 5.95 6.30 1 1.01 0.34 5.840 11.09 6 1.02 0.238 5.890 6.58 3 1.03 0.88 5.890 9.44 6 1.07 0.058 5.920 6.37 3 1.08 0.38 5.970 8.58 4 1.13 0.41 5.900 10.48 4 pH of developing solution e 10.75 processing time = 40 seconds temperature - 35"C Dot quality is an arbitrary scale 1 (worst), 6 (best) Table 2.2

t =40" Dmin Dmax Gamma pH 10.20 T/M 35"C Emulsion 0.43 6.010 5.56 A 0.37 6.040 5.08 1.01 0.34 5.960 6.67 1.02 0.35 5.940 10.56 1.03 0.36 5.900 5.95 1.08 0.039 5.960 5.56 1.13 0.040 5.940 5.79 1.14 0.044 5.940 5.72 pH of developing solution = 10.2 processing time = 40 seconds temperature = 35"C Table 2.3

pH 10.50 Processing Dmin Dmax Gamma 35 C time, sec. T/M 20 0.37 5.770 5.90 Emulsion 30 0.39 5.930 5.95 40 0.38 5.940 6.18 20 0.34 5.990 5.45 1.01 30 0.36 6.290 8.24 40 0.35 6.040 9.08 20 0.40 5.890 5.94 102 30 0.79 6.140 6.17 40 0.77 6.270 7.94 pH of developing solution = 10.5 temperature = 35 C Table 2.4 Comparison of water solubility

Compound Solubility in water (T 20 C) A < 1.3% B < 0.3% C < 16 1.08 10% 1.13 14% 1.14 4% Compound A B and C - Comparison Compound 1.08, 1.13, and 1.14 - Invention

Claims (22)

1. Claims:1. A hydrazide compound of the general formula 1:

   wherein U is an unsubstituted or substituted alkylene or arylene group with up to 8 carbon atoms, n and m are 1 or 0 and may be equal or different, R1 and R2 are independently an alkyl or isoalkyl group containing 1 - 4 carbon atoms, a substituted alkyl, an alkoxy or aralkoxy group with up to 12 carbon atoms or a halogen and where either R1 or R2 can also be hydrogen, or R1 and R2 together can form an aromatic or a partially unsaturated ring, R3 is H or alkyl with up to 4 carbon atoms, A+ is an activity regulating group, and G is an anion.
2. 2. A hydrazide compound according to claim 1 where in the compound of + formula 1 A is selected from groups of formulae I, II or III

   where Z denotes the atoms necessary to form an unsaturated, partially unsaturated or a fused heterocyclic ring, R4, R5, R6 and R7, R8, R9 are each equal or different and selected from the groups alkyl or isoalkyl C1-C8, substituted alkyl. aralkyl, phenyl and substituted phenyl, R5 and R6 can be linked to form a heterocyclic ring, R8 and R9 can be linked to form a heterocyclic ring, and G is an anion.
3. 3. A hydrazide compound according to claim 2 where in the group of formula I, Z denotes the unsubstituted or substituted elements necessary to form an aromatic five or six membered heterocyclic ring.
4. 4. A hydrazide compound according to claim 3 where a group of formula I is a triazolium residue and the following triazoles can be used to form the residue:
5. 5. A hydrazide compound according to claim 3 where the group of formula I is an imidazolium residue and the following imidazoles can be used to form the residue:
6. 6. A hydrazide compound according to claim 3 where group I is a pyridinium residue and the following pyridines can be used to form the residue:
7. 7. A hydrazide compound according to claim 2 where in the group II R4, R5 and R6 are each equal or different and are selected from alkyl, substituted alkyl, alkoxy or thioalkyl wherein the alkyl moiety has from 2 to 4 carbon atoms, or alkoxy or R5 and R6 can be linked to form a five or six membered ring.
8. 8. A hydrazide compound according to claim 7 wherein R5 and R6 are linked to form an N-alkyl piperidinium wherein the alkyl group has from 1 to 4 carbon atoms, N-hydroxyethylpiperidinium or N-methoxyethylpiperidinium.
9. 9. A hydrazide compound according to claim 7 wherein R and R are 5 6 linked to form an N-alkylmorpholinium where the alkyl group has from 1 to 4 carbon atoms, N-hydroxy - ethylmorpholinium or N-methoxyethylmorpholinium.
10. 10. A hydrazide compound according to claim 7 wherein R5 and R6 are linked to form an N-alkylpyrrolidinium where the alkyl group has from 1 to 4 carbon atoms, N-hydroxyethylpyrrolidinium or N-methoxyethylpyrrolidinium.
11. 11. A hydrazide compound according to claim 7 wherein R5 and R6 are linked to form N-butylpiperidinium, N-butylmorpholinium or N-butylpyrrolidinium.
12. 12. A hydrazide compound according to claim 7 in formula II R4, R5 and R6 are each the same alkyl having 1 to 8 carbon atoms.
13. 13. A hydrazide compound according to claim 2 where in the group III R7, R8 and Rg are phenyl, tolyl or alkyl groups having two, three or four carbon atoms.
14. 14. A hydrazide compound according to claim 2 where in the compound of formula 1 U is ethylene. propylene or 2-hydroxypropylene, n or m are 1 or 0 and G is chloride or bromide.
15. 15. A hydrazide according to claim 1 where in the compound of formula 1 R1 and R2 are each independently hydrogen, alkyl or substituted alkyl having up to 4 carbon atoms, alkoxy with up to 4 carbon atoms or halogen but only one of R1 or R2 can be hydrogen.
16. 16. A hydrazide according to claim 1 where in the compound of formula 1 G is mesylate, tosylate, bromide or chloride.
17. 17. A hydrazide according to claim 1 wherein n and m are each 0 and U is -(CH2)2-
18. 18. A hydrazide according to claim 1 wherein n and m are each 0 and the U-OH group is

    wherein R20 is alkyl having 1 to 4 carbon atoms.
19. 19. A hydrazide according to claim 1 of the general formula 2:

    where R1, R2, R3, U, G and A+ are as defined with reference to the compounds of formula 1 in claim 1.
20. 20. A hydrazide according to claim 1 of the general formula 3:

    where R1, R2, R3 and G are as defined in claim 1 U is ethylene, propylene, phenylene or substituted phenylene, and R10 is alkyl, isoalkyl, dimethylamino, pyrolidino, acylamino or sulphonylamino.
21. 21. A hydrazide according to claim 1 of the general formula 4:

    where R1, R2, R3 and G are as defined in claim 1 U is ethylene propylene, phenylene or substituted phenylene, R11, R13 and R14 are each hydrogen or methyl, and R12 is alkyl or substituted alkyl.
22. 22. Photographic silver halide material which comprises in at least one layer thereof at least one hydrazide as claimed in any one of claims 1 to 21.