SUPER-HIGH CONTRAST SILVER HALIDE MATERIAL

Abstract: A silver halide photographic material and a method for processing the photographic material to form a super high contrast negative image are disclosed. The photographic material comprises a radiation-sensitive silver halide grains capable of forming a surface latent image, a binder, a dot quality-promoting amount of a hydrazine or hydrazide compound and a pepper-reducing effective amount of a compound of formula (II), wherein R'1 is selected from the group consisting of benzothiazole, quinoline, indolenine, nitrobenzothiazole, benzotriazole and rhodanine, each of which may be substituted or unsubstituted, and m is an integer between 0 and 6 inclusive.

Description: SUPER-HIGH CONTRAST SILVER HALIDE MATERIAL FIELD OF THE INVENTION This invention relates to high-contrast silver halide photographic materials for use in the ield of graphic arts and to a process for reducing black spots ("pepper") in exposed photographic materials of the foregoing type. BACKGROUND OF THE INVENTION In the field of graphic arts / an image-forming system providing a super-high contrast photographic characteristic, especially one having a sensitivity ("gamma") of 10 or more, is required for satisfactory reproduction of continuous tone images or line images by dot images. For this purpose, a specific developer called a lith-type developer is generally used. The lith developer contains, as a developing agent, hydroquinone and, as a preservative, a sulfite usually in the form of an adduct with formaldehyde at a concentration of not more than 0.1 mol/l, thereby preventing deterioration of the infectious development ability of the developing agent. The lith developer has a serious disadvantage in that it is very susceptible to air oxidation and cannot withstand use for a period of time exceeding 3 days. Increasing the sulfite content of the developer improves its useful life but deteriorates its high-contrast development characteristics. Known ways to obtain equivalent or substantially equivalent high-contrast photographic characteristics with a stable developer include the use of hydrazine or hydrazide derivatives as described for example in U.S. Patent Nos. 4,224,401, 4,168,977, 4,166,742, 4,311,781, 4,272,606, 4,211,857 and 4,243,739 all incorporated by reference in their entirety. Use of hydrazine or hydrazide compounds in image formation systems provides super-high contrast and high sen¬ sitivity, and also ensures greatly improved stability of the developer against air oxidation as compared to the conventional lith developer because hydrazine (and/or derivative) presence in the film or in the developer permits use of a higher sulfite ion concentration in the developer. However, it has been found that use of hydrazine or hydrazide compounds in high-contrast image formation systems tends to cause black silver spots (also called "black pepper" or simply "pepper") on non-image area (i.e. in areas of no ex- posure), for example between dots. This phenomenon becomes particularly conspicuous when the sulfite ion content in a developer is decreased or the pH of a developer increases, e.g., due to fatigue of the developer, and causes significant impairment of photographic quality. Various attempts have hitherto been made to eliminate the problem of black spots, but whatever ad hoc improvement was achieved was frequently accompanied by reduction in sensitivity and gamma. For example, use of several hydrazides disclosed in U.S. Patent No. 4,686,167 (incorporated by reference in its entirety) describes several hydrazides which, when used in photographic emulsions, produce very good results including favorable pepper ratings. However, no general applicability means has been proposed for solving the problem of black spots without substantially hindering the ability of the above- described hydrazine or hydrazide compounds to increase sen¬ sitivity and contrast, especially as measured by dot quality. Moreover, although the hydrazides of U.S. Patent No. 4,686,167 produce low pepper when processed in fresh developer, the pepper increases upon processing in exhausted oxidized or inhibitor-contaminated developer. It is therefore desirable to provide a method for enhancing the performance of photographic materials by substantially reducing or eliminating pepper over a wide processing latitude (i.e. processing solution qualit and age) essentially without affecting the contrast an sensitivity properties of the processed photographic material. U.S. Patent No. 4,851,321 issued 7/25/889 to Takag discloses hydrazide-containing, low-sensitivity, high-contras photographic materials in which sensitivity (and pepper) ha been lowered by use of a development restrainer. Suc restrainers are said to ordinarily also lower contrast. According to this patent, contrast is not lowered because th photographic material also contains a contrast-enhancing com pound. The hydrazides specifically contemplated are for y phenyl hydrazides with various εubstituents and other function alities appended to the phenyl ring. The restrainers con templated ("organic desensitizers") are compounds having positive polarographic half-wave potential (Col. 24:57-65) an are represented by formulas disclosed at Col. 25-26. Specifi restrainer examples are disclosed at Col. 27-31 and include XI-1 2-[4,6 dinitrophenylthioether]-3-[benzene carboxylic acid]-imidazole, XI-3 2-[4,6 dinitrophenylthioether]-3-[benzene εulfonic acid]-benzei idazole, XII-1 5-[p nitrobenzelidine]-3-[carboxymethyl] rhodanine, and XIII-6 3-[m-nitrobenzelidene] rhodanine. The amounts of restrainer range between 10"^ and 10""^ mol/m^ (using 3.8 g Ag/m 2 ) (Col. 31:59-62). All of the Takagi photographic materials must contain a contrast-enhancing compound and are intended to have low sen¬ sitivity. Thus, Takagi does not provide a solution to the pepper problem of a high-sensitivity, high-contrast photographic material. U.S. Patent No. 4,737,442 issued 4/12/88 to Yogihara discloses photographic materials containing a formyl phenyl hydrazide (or certain derivatives) as well as a restrainer of the type C A -B wherein C A is a blocking group capable of releasing during the development process a development restrainer or a precursor thereof regardless of the degree of exposure of the photographic material, and D is a restrainer or a precursor of a restrainer. Examples of restrainers include: 1-(2,4-dihydroxyphenyl)-5-mercaptotetrazole, 4-phenyl-5-methyl-3-mercaptotetrazole, 5-nitro-2-mercaptobenz.imidazole, 2-mercaptobenzoxazole, benzimidazole, and 6-nitroindazole. The purpose of adding the restrainer is to avoid pepper. The amount of restrainer ranges between about 5.4x10"^ to 1 10"! mole/mole Ag. The restrainers disclosed in the '442 patent are of the so-called "stabilizer" type which form strong silver salts and not of the "antifoggant" type. Stabilizer- type restrainers would decrease speed markedly more than antifoggant-type compounds when used with hydrazides, notably the hydrazides of the Formula I, below. U.S. Patent No. 4,839,259 issued 6/13/89 to Sasaoka discloses hydrazide-containing photographic materials that are said to have simultaneously high sensitivity (gamma) and are free (or substantially free) of black spots or pepper. The pepper-free quality according to the patent is imparted by the use of dual developing agents in combination with a sulfite preservative and a pH in the range of 10.5-12.3. Optional ingredients include sensitizing dyes to improve emulsion sensitivity and/or various conventional antifoggant/stabilizers such as benzothiazoleε, nitrobenzothiazoles, benzotriazoles, etc. (Col. 10:26-46). The antifoggantε can be added to the developer. U.S. Patent No. 4,789,618 isεued 12/06/88 to Inoue et al diεcloεeε "black-spot" prone hydrazide-containing photographic materialε in which black spotε are εaid to be reduced or prevented by incorporation of an oxidizing agent (at 10~5 _ i mole/mole Ag) such aε N-bromoεuccinimide, hydrogen peroxide and its addition products, peroxy acid saltε, peroxy complexeε , ozone, etc. Conventional antifoggant εtabilizers such as azoles, mercaptobenzothiazoles, nitrobenzotriazoles, etc. are listed as optional ingredients (Col. 11:4-24) for their conventional antifoggant/stabilizer purpose, as i Saεaoka. U.S. Patent No. 4,785,587 issued to Kuwabara o 11/22/88 diεcloεes hydrazine-containing photographic material of high-sensitivity, and "very high" contrast in which peppe is said to be reduced by using two different silver halid emulsions which differ in mean grain size (within specifie limitε). Thiazoles and rhodanineε are diεclosed as (optional) sensitizers. Antifoggants/stabilizers such as thiazoles, etc. are also disclosed as optional ingredients (Col. 13:37-60). European Application No. A2 306,833 of Fuji Photo Fil published on 3/15/89 discloses photographic materials of hig contrast and sensitivity containing a hydrazine derivative an two additional compounds; a photographic restrainer bearing a late-absorbin group P R (Time) t - LA(1) and a tetrazole derivative. Antifog- gants/εtabilizers are also added. Pepper reduction iε at¬ tributable to the electron-withdrawal propertieε of the nitro group. European Application No. A^ 286,840 discloses allegedly reduced-pepper photographic materialε compriεing a hydrazine compound of the Formula: A l A 2 R 1 -S0 2 -NH-Y-N—N-G-R 2 wherein G is CO, sulfonyl, sulfoxy, phosphoryl or N-εubstituted or unsubstituted iminomethylene. The pepper-reducing proper¬ ties are attributable to the hydrazide. None of the above-cited documents (the disclosure of which is incorporated by reference) disclose use of a small amount of antifoggant/stabilizer of Formula II to reduce pepper, nor a combination of the hydrazide of U.S. Patent No. 4,686,167 with a pepper-reducing effective amount of a stabilizer/antifoggant in h gh-contrast, high-sensitivity photographic materials. SUMMARY OF THE INVENTION Accordingly, an object of thiε invention is to provide a highly sensitive high-contrast silver halide photographic material which can be developed with a stable developer in the presence (in the photographic material or in the developer) of a hydrazine or hydrazide contrast-enhancing compound to obtain a super-high contrast image with substantial reduction or elimination of black spots. Another object of this invention is to provide a method for reducing or eliminating black spots upon development of a silver halide photographic material which contains, or which is developed in a developer containing, a hydrazine or hydrazide compound and which yields a super-high contrast negative image. The above objects can be accomplished by the incorpora¬ tion in a photographic material or in its developer of a compound within Formula II below in an amount effective to reduce or eliminate black spot formation but not capable of εubεtantially affecting εensitivity or contraεt (i.e. not reduce εenεitivity more than about 10% or εpeed more than about a quarterstop or decrease the value of gamma below 10) . Preferably, use of this compound is made in a negative-working surface-latent image syεtem (but the preεent invention is not limited to such systems) . The Formula II compound is preferab¬ ly incorporated in the photographic material, in at least one of the emulsion layer or in another (e.g. a hydrophilic colloid) layer coated on the photographic material support. Most preferably, the photographic material compriseε the following: a εupport having provided thereon at leaεt one εilver halide emulsion layer, wherein said emulsion layer or another layer of the εilver halide photographic material provided on the support containε at leaεt one compound repreεented by the Formula I and alεo containε at leaεt one compound of the Formula II. It iε again emphaεized, however, that the preεent invention iε not limited to hydrazide deriva¬ tives of Formula I not to hydrazines or hydrazideε preεent in the film. Formyl phenyl hydrazide could, for example, be uεed in the developer with a compound of Formula II in the film in accordance with the preεent invention. A super-high contraεt negative image iε formed by a process comprising i agewise exposing a hydrazine- o hydrazide- containing photographic material (preferably material containing a Formula I compound) to light and develop ing the exposed material with a developer containing dihydroxybenzene derivative (as a developing agent), a ben zotriazole antifoggant, a sulfite preεervative and an effectiv amount of an amine compound. Compounds of Formula I include: Y 00 tl M II R 1 (NR 2 ) π CN-R -NHNHCCX (Formula I) R3 wherein: X«-NR5Rg, or -0R 7 ; Ri and R 2 are independently hydrogen and substituted o unsubstituted (i) alkyl, having up to 18 carbons; (ii) cycloalkyl; (iii) phenyl or naphthyl or (iv) aryl sulfonyl. R3 is hydrogen, phenyl or benzyl, the latter tw substituted or unsubεtituted, but if neither ^ nor R 2 iε hydrogen then R3 is hydrogen. R4 iε a εubstituted or unsubstituted divalent aromatic group. R 5 , Rg, and R7 are independently hydrogen, εubεtitute or unεubstituted (i) alkyl having up to 12 carbonε; (ii) cycloalkyl; (iii) phenyl or naphthyl. -L and R3 or R^ and R 2 can be linked to form a heterocyclic ring εyεtem with the ring containing three to ten ato ε. R 5 and Rg can be linked to form a heterocyclic ring εyεtem with the ring containing 3-10 atomε. Y iε an oxygen or sulfur atom; n=0,l, but if Y iε εulfur then n=l. Suitable εubεtituentε include without limitation halogen, hydroxy, alkoxy, amino, alkylamino, aryl, arylamino, cyano, acylamino. The εubstituents themselves may be further subεtituted. Compoundε of Formula II, include compounds containing one moiety selected from the group consisting of ben- zothiazoles, quinolines, indolenine benzotriazoles, and rhodanines having one or more nitro groups attached to a benzene nucleus, which is either a part of the heterocyclic compound or is attached to it through a doubly-bonded carbon- to-carbon chain. The quaternary εalts (such as ammonium, triethylamine, piperidine and alkali metal salts, preferably methanol-εoluble) of the benzothiazoleε, quinolines and in- dolenineε are alεo suitable. Compounds of Formula II are defined as follows: wherein m is an integer between 0 and 6 inclusive; R^ is selected from the group conεiεting of benzothiazole, quinoline, indolenine, nitrobenzothiazole, benzotriazole and rhodanine, each of which may be unεubεtituted or εubεtituted by, e.g. halogen, hydroxy, alkoxy, aryl, amino, arylamine, εulfuric acid, carboxylic acid, phenyl, etc., or fused to the nitroben¬ zene nucleus. Preferably, ^ is substituted by hydrogen or carboxy and m is 1. Furthermore, the substituentε in R j are preferably in the 3-poεition if the ring S is 1 and numbering is clock¬ wise. DETAILED DESCRIPTION OF THE INVENTION Several of the compounds repreεented by Formula II according to the preεent invention were previouεly known and uεed as photographic stabilizerε/antifoggantε (in amountε generally ranging between about 10 ** ^ and about 1 moleε/mole Ag) to improve the speed constancy of photographic emulsions. Unexpectedly, in experiments testing the ability of such compounds to improve speed stability of εilver halide emulεionε containing hydrazide derivativeε, eεpecially hydrazide deriva- tiveε of the Formula I type, it waε diεcovered that εuch compoundε also reduced and/or eliminated "pepper" in a con- centration-dependent manner but at very small concentrations. 0/07454 Moεt unexpectedly, at εuch εmall concentration, such compound remarkably reduce or eliminate black spots without inhibitin the ability of the compound represented by the Formula I t increase sensitivity and contraεt. The range of εubstantia pepper reduction effectiveness of such compounds iε generall between about 5xl0~ 8 and about 1x10"^ moles/mole Ag an preferably about 10" 5 to about 10~ 4 moles/mole Ag. (Th present emulsion is preferably uεed at 3.6 g Ag/m 2 .) The compound of the Formula I or another contraεt enhancing hydrazide and the compound of the Formula II ar preferably incorporated into the same layer, but may alεo b incorporated into different layers or the compound of Formula I can be used in the developing solution. In the general Formula I described above, R^ preferably represents a hydrogen atom, an unsubstituted or εubεtitute alkyl group (εuitable preferred εubstituents include without limitation alkyl, cyano, halo, or alkoxy), a substituted or unsubstituted cycloalkyl group or a substituted or unsub¬ stituted arylsulfonyl group. The total number of carbon atoms in ^ can be up to 18 but preferably, should be lesε than 12. Moεt preferably, R^ is unεubεtituted alkyl or cycloalkyl containing 1-6 carbon atomε. R is independently chosen from the group representing Rι_; preferably, however, the total number of carbon atoms between Rj and R 2 εhould not exceed 12. 3 preferably repreεentε a hydrogen atom, an unsub- εtituted or εubεtituted benzyl group (suitable preferred sub- εtituentε include without limitation alkoxy, halo or alkyl). If neither R^ nor R 2 iε hydrogen, then R3 must be hydrogen. Most preferably, R3 iε hydrogen. In the preferred case, Y is a sulfur atom. If Y iε a sulfur atom then n=l. In the most preferred case n=l. R4 preferably repreεents either an unsubstituted or substituted divalent aromatic group. Suitable subεtituentε include without limitation alkyl, alkoxy, halo, or acylamino functionalitieε. In the moεt preferred case R4 is phenylene with the thioamide or amido group in the ortho- or para-posi- tion relative to the hydrazido group. Furthermore, it iε preferred that any suitable εubεtituent aε deεcribed herein be attached at a remaining, unoccupied ortho- or para-poεition relative to the hydrazine group. R5 preferably repreεentε either a hydrogen atom, an unεubεtituted or subεtituted alkyl group (suitable preferred εubεtituentε include hydroxy, halo, alkoxy, alkylamino, acylamino, amino and aryl εuch as phenyl), a cycloalkyl group, an unsubεtituted or εubεtituted aryl group (εuitable preferred substituents include alkyl, cyano, halo or alkoxy) or an unsub¬ stituted or subεtituted amine. The total number of carbon atoms in R5 εhould be up to 12. Preferably, R5 ±ε alkyl, cycloalkyl, dialkylaminoalkyl or acylaminoalkyl each -containing 1-6 carbon atoms. Rg and R7 are independently chosen from the group representing R5; preferably, however, the total number of carbon atoms between R5 and Rg εhould not exceed 12. In addition, R5 and Rg preferably do not contain amino functionalitieε that are directly linked to the nitrogen atom of X. Furthermore, R5 and Rg can be linked to form a heterocyclic ring syεtem with the ring containing 3-10 atomε. Additionally, either R^ and R3 or R^ and R 2 can be linked to form a heterocyclic ring εyεtem with the ring containing 3-10 atomε. The preferred compoundε repreεented by the general Formula I are thoεe repreεented by the general Formula (IA) . 00 // NX (Formula IA) R 8 NHCNH - - NHNHCCZR9 In thiε formula, Y = S or 0; Z = 0 or HN; Rg and Rg have the εame meaning aε R^ and R5 reεpectively for the above deεcribed general Formula I. Moεt preferably Rg is ethyl, n-butyl or cyclohexyl, Rg is hydrogen, methyl, ethyl, dimethylaminoethyl or acetylaminoethyl, Z = HN, and Y = S. Specific examples of the compounds represented by the general Formula I are given below in Table I, but the presen invention iε not limited to these examples. In fact, th present invention broadly involves the .use or incorporation o a Formula XI compound, in an amount sufficient to reduce o eliminate pepper, in any high-contrast image forming syste (photographic material and/or developer} containing a contrast enhancing amount of a hydrazine or hydrazide compound. TfiE E I GH 2 Ph SUBSTITUTE SHEET TABUS I f∞NTIMJED) (1-13) (1-14) (1-15) (1-16) (1-17) (1-20) (1-21) SUBSTITUTE SHEET TftBEE I (CONTINUED. (1-22) (1-23 (1-24) (1-25 (1-26) (1-27) (1-28) (1-29) The amount of the compound of Formula I added to the εilver halide emulsion layer or to one or more hydrophilic colloidal layer(ε) iε εuch that the compound enhances contraεt but does not appreciably function aε a developer. Typically, amounts from about 10 -m-B to about 5x10 -3 moles/mole Ag and preferably from about 10 -5 to about 5x10-4 mole/mole Ag are uεed. In the above described Formula II the electron-accept¬ ing compounds are compounds having one or more nitro groups attached to a benzene nucleus which is either a part of the heterocyclic compound or iε attached to it through a doubly bonded carbon-to-carbon chain as described in US Patent 2,541,472 (incorporated by reference) . Specific but non-limiting examples of Formula II according to our present invention are shown below. Generally suitable amounts of the Formula II compound are within the range of about 10-^ to about 10 " ^ moles/mole Ag, with about l l0~ -to about x10"^ being preferred. This is different from the stabilizer effective amounts, which as stated above, are much SUBSTITUTE SHEET higher in the syεtem employing Formula I hydrazideε. In other εyεtems (e.g. using different hydrazides or different εilver halide emulεionε, etc.) the conventional εtabilizing/antifoggant amounts may be different but the anti-pepper effective amounts 5 are also anticipated to be much εmaller. The anti-pepper effect will perεiεt at higher a ountε but aε the amount of Formula II compounds approacheε or reaches the antifoggant/stabilizer effective range, sensitivity will (begin to) be affected, which is undesirable in the preεent invention. Table I below liεtε 10 compoundε within Formula II aε an illuεtration. It εhould be underεtood that any combination of the Table II groupε R and left and right moiety εubstituentε are fully within the εcope of Formula II and the preεent invention, not only individually but alεo generally (e.g. "methyl" εhall be an illuεtration of alkyl, 15 etc. ) . - N0 2 II-3 \ N0 II-6 \ N0 2 II-7 \ H N0 2 II-9 \ 0 2 11-12 \ N0 2 N0 2 1-21 11-23 N0 2 N0 2 11-25 Aε εtated above, the pepper-reducing amountε of the Formula II compounds εhould not be higher than about 10"^ moleε/mole Ag in order to avoid deεenεitization and loεε of contraεt, the latter due to interference with the contraεt- enhancing function of the (e.g. Formula I) hydrazide. The compounds of Formula I and II can be incorporated in the photographic element by well-known techniques uεed for the incorporation of additives to photographic emulsionε or elementε. The compounds are typically disεolved in a εolvent εelected from organic solvents compatible with water, such aε alcoholε, glycolε, ketones, esters, amides, and the like which exert no adverse influences on photographic characteristicε, and the εolution iε added to the photographic element. Preferred εolvents include dimethylformamide (DMF), dimethylsulfoxide (DMSO) and N-methyl-2-pyrrolidinone (NMP). Alternatively, the compound of Formula I and II can be added to an emulsion in a disperεion by known methodε uεed when water-inεoluble (εo-called "oil εoluble") couplerε are added to emulsions. Preferred oils include N-butyl acetanilide, N-methyl formanilide and N,N-diethyl-m-toluamide. These oils are commer¬ cially available. Ultrasound can be employed to disεolve (more preciεely finely diεperεe) marginally εoluble ethanedioic acid hydrazideε. These solutions or dispersions can be added to the photographic emulsion at any stage εubεequent to the emulεion precipitation and waεhing εtepε. Preferably theεe agentε εhould be added during chemical ripening or juεt prior to coating. Gelatin iε advantageouεly uεed aε a binder or protec¬ tive colloid in the photographic emulεion, but other hydrophilic colloidε can alεo be used. For example, gelatin derivatives, graft polymers of gelatin with other high molecular weight materials, proteins such aε albumin or caεein; celluloεe deriva- tives such as hydroxyethyl cellulose, carboxymethyl cellulose or celluloεe εulfate, εaccharide derivativeε εuch aε εodiu alginat or starch derivativeε, polyglycoεide dextranε and variou synthetic hydrophilic high molecular weight materialε εuch aε homopolymerε or copolymerε of e.g., polyvinyl alcohol, polyvinyl alcohol (partial acetal), poly-N-vinyl pyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide, polyvinyl imidazole, polyvinyl pyrazole, etc., can alεo be uεed. Gelatin iε preferred. All theεe materialε are well-known and commercially available. ime-procesεed gelatin and acid-processed gelatin can alternatively be used as the gelatin. Hydrolyzed or enzyme- decompoεed gelatin can alεo be uεed. Suitable gelatin deriva¬ tives are prepared by reacting gelatin with various * compounds εuch as acid halides, acid anhydrides, isocyanateε, bromoacetic acid, alkaneεulfoneε, vinylεulfonamideε, maleinimide compoundε, polyalkylene oxides or epoxy compounds and, preferably, with phthalic anhydride or succinic anhydride. Specific examples of these gelatin derivatives are described in e.g., U.S. Patent Nos. 2,614,928, 3,132,945, 3,186,846 and 1,005,784, all incorporated by reference. Exampleε of εuitable gelatin graft polymerε include thoεe prepared by grafting a homopolymer or a copolymer of a vinylic monomer εuch aε acrylic acid, methacrylic acid, the derivatives thereof (such as the esters or the amides thereof), acrylonitrile or styrene to gelatin. In particular, graft polymerε prepared from polymers which are compatible with gelatin to some degree, such as those of acrylic acid, methacrylamide or a hydroxyalkyl methacrylate which are preferred. Exampleε of those polymers are described in, e.g., U.S. Patent Noε. 2,763,625, 2,831,767 and 2,956,884. Typical εynthetic hydrophilic high molecular weight materials are described in, e.g., German Patent Application (OLS) 2,312,708, U.S. Patent Noε. 3,620,751 and 3,879,205, all incorporated by reference. The photographic emulεion uεed in thiε invention can be prepared uεing the well-known methodε described in, e.g., P. Glafkides, Chimie et Phyεique Photographique, Paul Montel, Pariε (1967), G. F. Duffin, Photographic Emulεion Chemiεtry, The Focal Preεs, London (1966), V. L. Zelikman et al.. Making and Coating Photographic Emulεions, the Focal Presε, London (1964), all incorporated by reference. Theεe methodε include the acid method, the neutral method, the ammonia method and others. Moreover, a εoluble εilver εalt can be reacted with a soluble halogen εalt using any of the εingle jet method, the double jet method and a combination thereof. The well-known method of forming grainε in " the presence of an excesε of εilver ionε (the εo-called "reverse mixing method") can alεo be uεed. The "controlled double jet method" (alεo called "controlled diffuεion method") iε preferred. According to thiε method, the pAg of the liquid phaεe (in which the εilver halide iε to be produced) iε kept constant. This method can provide silver halide" emulsionε having a regular cryεtal form and an almost uniform grain size. The εilver halide grainε in the photographic emulεion uεed in thiε invention can have a relatively wide grain εize distribution, but a narrow grain size distribution is preferred. In particular, the εize of the εilver halide grainε amounting to 90% of the total, based on the weight or number of the grains, iε preferably within + 40% of the average grain εize (εuch an emulεion iε usually called a monodiεperεed emulεion). Grain εize can be controlled by known techniqueε εuch aε are diεcloεed in, e.g. U.S. Patents No. 3,271,157; No. 3,704,130; No. 3,574,628; No. 4,276,374 and No. 4,297,439 and in Research Discloεureε RD No. 17643, December 1978 and 18716, November 1979, all incor¬ porated by reference. The individual reactantε can be added to the reaction veεsel through surface or εub-εurface delivery tubeε by gravity feed or .by delivery apparatuε for maintaining control of the pH and/or pAg of the reaction veεsel contentε, aε illustrated by Culhane et al U.S. Patent No. 3,821,002, Oliver U.S. Patent No. 3,031,304 all incorporated by reference. In order to obtain rapid distribution of the reactants within the reaction veεsel, εpecially conεtructed mixing deviceε can be employed, aε il- luεtrated by Audran U.S. Patent No. 2,996,287, McCrossen et al U.S. Patent No. 3,342,605, Frame et al U.S. Patent No. 3,415,650, Porter et al U.S. Patent No. 3,785,777, Saito et al German OLS 23 No. 2,556,885 and Sato et al German OLS No. 2,555,364 all incor¬ porated by reference. An encloεed reaction vessel can be employed to receive and mix reactantε upstream of the main reaction vessel, as illustrated by Forster et al U.S. Patent No. 3,897,935 and Posεe et al U.S. Patent No. 3,790,386, all incor¬ porated by reference. The grain εize distribution of the silver halide emulsions can be controlled by εilver halide grain separation techniqueε or by blending εilver halide emulεionε of differing grain sizes. The emulεionε can include ammoniac l emulsions, as illustrated by Glafkides, Photographic Chemiεtry, Vol. 1, Fountain Preεε, London, 1958, pp. 365-368 and pp. 301-304; thiocyanate ripened emulεions, aε illuεtrated by Illingεworth U.S. Patent No. 3,320,069; thioether ripened emulsions, as il¬ lustrated by McBride U.S. Patent No. 3,271,157, Jones U.S. Patent No. 3,574,628 and Rosecrantε et al U.S. Patent No. 3,737,313 or emulsions containing weak silver halide εolventε, εuch aε ammonium εaltε, as illustrated by Perignon U.S. Patent No. 3,784,381 and Research Discloεure, Vol. 134, June 1975, Item 13452 all incorporated by reference. The method using ammonium εalts is preferred. The crystal form of the εilver halide grainε in the photographic emulεion may be regular (εuch aε cubic or oc¬ tahedral) or irregular (εuch aε εpherical or plate-like) or it may be a compoεite of theεe forms. The grains may comprise mixed grains having various crystal forms. The interior and the surface layer of the silver halide grain may be different or the grainε may be uniform throughout. During the proceεε of the formation or physical ripening of the grains, cadmium saltε, zinc saltε, lead εaltε, thallium εaltε, rhodium εaltε or complex saltε thereof, iron εaltε or iron complex εaltε, and the like can be preεent, aε can mixtureε thereof. Preferred as εuch dopants, are rhodium or iridium salts or mixtures thereof. Two or more of silver halide emulεions which are separately prepared can be mixed and then used, if desired. After the formation of the precipitates or after phyεical ripening, the εoluble εaltε are usually removed from the emulsion. For thiε purpose, the well known noodle washing method may be uεed. Alternatively, the flocculation method may be uεed. Thiε method employε an inorganic εalt having a polyvalent anion εuch aε εodium εulfate, an anionic εurface active agent, an anionic polymer (εuch as polystyrene εulfonic acid) or a gelatin derivative (εuch as an aliphatic acylated gelatin, an aromatic acylated gelatin or an aromatic carbamoylated gelatin) . The removal of the soluble εaltε may be omitted, if deεired. Although the εilver halide emulεionε uεed in the preεent invention do not need to be chemically εenεitized, chemically εenεitized εilver halide emulεions are preferred. Procesεes for chemical εenεitization of the εilver halide emulsions which can be used include known sulfur sensitization, reduction εenεitization and noble metal εenεitization proceεεeε. In addition to εulfur sensitization, selenium, tellurium, rhenium or phoεphoruε εensitizerε or combinationε of these senεitizerε can be uεed. Chemical ripening can be performed at pAg levelε of from 5 to 10, pH levelε of from 5 to 8 and at temperatureε from 30° to 80 β C. Theεe processes are described in references such as P. Glafkides, Chimie et Phyεique Photographique, Paul Montel, Pariε (1967) or Zelikmann, Making and Coating Photographic Emulεionε, The Focal Press, London (1964) or H. Frieser, Die Gundlagen der Photographiεchen Prozeεεe mit Silberhalogeniden, Akademiεche Verlagεgeεellεchaft (1968). The disclosure of these references iε incorporated by reference. In the noble metal εenεitization processeε, a gold εenεitization proceεε iε a typical proceεε where gold compoundε or gold complexeε are uεed. Complexeε of noble group VIII metals other than gold, such aε those of platinum, palladium, osmium, rhodium or iridium, etc. can alεo be uεed aε chemical εenεitizerε. A reduction εensitization process may be used if the process does not generate fog to a degree which causes practical difficulties (with or without the use of known antifoggentε) . A particularly preferred chemical εenεitization proceεε for the present inven¬ tion is the use of a sulfur senεitization proceεε. Examples of εulfur εensitizing agents which can be used include not only sulfur compounds present in the gelatin per εe, but alεo various εulfur compoundε εuch as thiosulfates, thioureas, thiazoles or rhodanines, etc. Examples of suitable εulfur compoundε are described in U.S. Patent Nos. 1,574,994, 2,410,689, 2,278,947, 2,728,668 and 3,656,955, all incorporated by reference. Typical exampleε of reduction-sensitizing agentε include εtannouε εalts, amines, formamidine sulfinic acid and εilane compoundε, methyldichloroεilane, hydrazine derivativeε, boranes such aε aminoboraneε, thiourea dioxide, hydrogen, and other boron hydrides εuch as cyanoborohydrides. Reduction senεitization can alεo be obtained by low pAg (leεε than 5) or high pH (greater than 8) treatment, aε iε well-known in the art. Specifically contemplated iε the combined uεe of εeveral of the aforementioned chemical ripening techniqueε; in particular gold-εulfur εenεitization combinations are highly preferred. A photographic material used in thiε invention may contain an antifoggant. Examples of antifoggants which can be advantageously used for the photographic material uεed in thiε invention are 1,2,4-triazole compoundε εubεtituted with a mercapto group at the 3-poεition, benzotriazole compounds, 2-mercaptobenzimidazole compounds (which do not contain a nitro group), 2-mercaptopyrimidines, 2-mercaptothiazoleε, 2-mercap- tobenzothiazoleε, benzothiazolium compoundε (εuch aε N-alkylben- zothiazolium halideε, nitrobenzindazole, εubstituted triazain- dolizineε (tetraazaindeneε) or N-allylbenzothiazolium halideε), and 2-mercapto-l,3,4-thiazoleε. Antifoggants which are not effective when used alone, such a 6-nitrobenzimidazole, however, can be used in combination with advantageous antifoggants. It has been observed that both fog reduction and an increase in contraεt are obtainable by employing benzotriazole antifoggants. When the benzotriazole is located in the photographic element concentrations of 10 -4 to 10-1, preferably 10 —3 to 3x10—2, mole per mole of silver are employed. Useful benzotriazoles can be chosen from among conven¬ tional benzotriazole antifoggants, εuch as those disclosed by Land U.S. Patent No. 2,704,721 and Rogers et al U.S. Patent No. 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-methylbenzotriazole is most preferred. The use of 5-methylbenzotriazole as an antifoggant is illustrated by Baldassari et al U.S. Patent No. 3,925,086, incor¬ porated by reference. The effect of this invention is enhanced even more by adding a small amount of an iodide salt (such as potassium iodide) to the emulsion after the formation of the grains, before chemical ripening, after chemical ripening or before coating. A suitable amount of iodide added ranges from about 10 -4 to about -2 10 mol/mol Ag. Larger amounts are not harmful but are unneces¬ sary. Smaller amounts may still be effective in isolated cases but as a general rule amounts within the aforementioned range should be used. The photographic emulsions used in this invention can be used for camera exposure. To insure good safelight protection UV absorbing compounds are used, such as those in U.S. Patents Nos. 3,533,794; 3,314,794 and 3,352,681, all incorporated by reference. Safelight dyes such as oxonols, hemioxonols, styryl dyes, merocyanine dyes and aso dyes can also be used, as long as such dyes are easily removed or decolorized during processing (see US Patents Nos. 2,274,782; 2,956,879; 3,423,207; 3,976,661 and 3,384,487, all incorporated by reference). Desensitizing dyes (see, e.g. U.S. Patent No. 3,501,307, incorporated by reference) can alεo be uεed. The preεent emulsion can be spectrally sensitized (e.g. to long blue, green, red or infrared) with at least one methine- type and/or other spectrally-sensitizing dye. Suitable sensitiz- ing dyes include cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes, holopolar cyanine dyes, hemicyanine dyes, styryl dyes and hemioxonol dyes. Particularly 07 54 27 uεeful dyeε are cyanine dyes, merocyanine dyes and comple merocyanine dyes. These dyes can contain, as a basi heterocyclic nucleus, any of the nuclei which are usuall employed in cyanine dyes: a pyrroline nucleus, an oxazolin nucleus, a thiazoline nucleus, a pyrrole nucleus, an oxazol nucleus, a thiazole nucleus, a εelenazole nucleus, an imidazol nucleus, a tetrazole nucleus, a pyridine nucleuε and the like; one of the above-deεcribed nuclei condenεed with an alicyclic hydrocarbon ring; and one of the above-described nuclei condenεe with an aromatic hydrocarbon ring, such as an indolenine nucleus, a benzindolenine nucleuε, an indole nucleus, a benzoxazole nucleus, a naphthoxazole nucleus, a benzothiazole nucleus, a naphthothiazole nucleus, a benzoselenazole nucleus, a ben- zimidazole nucleus and a quinoline nucleus. The carbon atoms of the above-described nuclei may be mono- di- or poly-εubεtituted with εuch diverεe εubεtituentε as alkyl, aryl, carboxy, εulfo, phenyl, alkoxy and halo, without limitation, and, optionally themεelveε further εubεtituted. The merocyanine dyeε or complex merocyanine dyeε can contain, as nucleus having a ketomethylene structure, a 5- to 6-membered heterocyclic nucleus εuch 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 nucleuε. Uεeful εenεitizing dyes include those described in, e.g., German Patent No. 929,080, U.S. Patent 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 Patent No. 1,242,588, all incorporated by reference. Preferred εenεitizing dyeε include dicarbocyanine derivativeε and tricarbocyanine derivativeε (moεt preferably symmetric) sensitizing within the range of about 680 to about 850 nm. Theεe εensitizing dyes may be used individually or as a combination. A combination of sensitizing dyes is often employed particularly for the purpoεe of εuperεenεitization. Typical exampleε of εuch combinationε are deεcribed in, e.g., U.S. Patent Noε. 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 3,837,862, and Britiεh Patent No. 1,344,281, all incorporated by reference. Preferred sensitizing dye combina¬ tions are mixtures of cyanine and merocyanine dyeε that or- thochromatically εenεitive at wavelengthε between 400 and 580 nm. The εensitizing dyes may be present in the emulεion together with dyeε which themεelveε do not have any εpectral εenεitizing effectε but exhibit a εuperεenεitizing effect when uεed in combination with εenεitizing dyeε, or with other materialε which do not substantially absorb visible light but exhibit a εuperεensitizing effect when used in combination with senεitizing dyeε. Exampleε of εuch materialε are dyeε, heterocyclic mercaptanε, εtyryl bases, "Q" salts (e.g. quaternary ammonium saltε) and high-molecular weight εulfonic acidε εuch aε εtilbeneε. More εpecifically, exampleε include εtilbene εuch aε aminoεtilbene compounds preferably εubεtituted with a nitrogen-containing heterocyclic ring group (e.g., thoεe described in U.S. Patent Nos. 2,933,390 and 3,635,721), aromatic organic acid formaldehyde condensates (e.g., those described in U.S. Patent No. 3,743,510), azaindene compounds, and the like, can be present. The combinations described in U.S. Patent Nos. 3,615,613, 3,615,641, 3,617,295 and 3,635,721 are particularly useful. (The diεcloεure of all patentε mentioned in thiε paragraph iε incorporated by reference.) A water-εoluble dye may be preεent in any of the hydrophilic colloid layerε in the photographic light-εenεitive materialε uεed in thiε invention, for example, aε a filter dye or for prevention of light εcattering, or for antihalation. Exampleε of theεe dyeε include oxonol dyeε, hemioxonol dyeε, εtyryl dyeε, merocyanine dyeε, cyanine dyeε and azo dyeε. Of theεe dyeε, oxonol dyeε, hemioxonol dyeε and merocyanine dyeε are particularly uεeful. Specific exampleε of dyeε which can be uεed are thoεe deεcribed in Britiεh Patent Noε. 584,609 and 1,177,429, and U.S. Patent 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. An inorganic or organic hardener may be present in any of the hydrophilic colloid layers in the light-sensitive material used in thiε invention. Theεe hardeners include, for example, chromium salts (such aε chrome alum or chromium acetate), aldehydes (εuch as formaldehyde, glyoxal or glutaraldehyde), N-methylol compounds (such as dimethylolurea or methyloldimethyl- hydantoin), dioxane derivatives (such aε 2,3-dihydroxydioxane), active vinyl compounds (such as 1,3,5-tri- acryloyl-hexahydro-s-triazine or bis(vinylεulfonyl)methyl ether), active halogen compoundε (such aε 2 , 4-dichloro- 6-hydroxy-ε-triazine), mucohalic acidε (εuch aε mucochloric acid or mucophenoxychloric acid), isooxazoles, dialdehyde starch, 2-chloro-6-hydroxytriazinylated gelatin and the like can be uεed individually or in combination. Specific exampleε- of theεe compounds are described, e.g., U.S. Patent Nos. 1,870,354, 2,080,019, 2,726,162, 3,870,013, 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 Patent Nos. 676,628, 825,544 and 1,270,578, German Patent Nos. 872,153 and 1,090,427, all incor¬ porated by reference. A preferred hardener is one that will not cause reduction-senεitization (formaldehyde, for example, εhould be avoided). An example of a preferred hardener iε dichlorohydroxytriazine. The light-εenεitive material of thiε invention may contain various known surface active agents for variouε purpoεes, e.g., as a coating aid, for preventing the generation of static charges, improving slip characteriεticε, improving emulεion diεperεion, preventing adheεion, improving photographic charac¬ teriεticε (e.g., accelerating development, increaεing contraεt, sensitization) , etc. Examples of suitable εurfactantε are: nonionic εurface active agentε such as saponin (εteroids) , alkylene oxide deriva- tives (εuch aε polyethylene glycol, polyethylene glycol/polypropylene glycol condenεateε, polyethylene glycol alkyl or alkylaryl ethers, polyethylene glycol esters, polyethylene glycol sorbitan esters, polyalkylene glycol alkylamines or amides or εilicone/polyethylene oxide adducts), glycidol derivatives (such as alkenylεuccinic acid polyglycerideε or alkylphenol polyglycerides) , aliphatic eεterε of polyhydric alcohols, alkyl esterε of sucrose, urethanes or ethers; anionic surface active agentε containing an acidic group εuch aε a carboxy group, a εulfo group, a phoεpho group, a εulfuric acid eεter group or a phoεphoric acid eεter group, such aε triter- penoid type εaponin, alkylcarboxylateε, alkylεulfonates, alkyl- benzenesulfonateε, alkylnaphthaleneεulfonateε, alkyl εulfuric acid esters, alkyl phosphoric acid esterε, N-acyl-N-alkyl- taurines, εulfoεuccinateε, εulfoalkylpolyoxyethylene alkylphenyl etherε or polyoxyethylene alkylphoεphateε; amphoteric εurface active agentε εuch aε amino acidε, aminoalkylεulfonic acidε, aminoalkylεulfuric acid eεterε, aminoalkylphoεphoric acid eεterε, alkylbetaineε, amineimideε or amine oxides; and cationic εurface active agentε εuch aε alkylamine εaltε, aliphatic or aromatic quaternary ammonium εalts, (εuch as pyridinium or imidazolium εaltε) or phoεphonium or εulfonium εaltε containing an aliphatic or heterocyclic ring. Specific exampleε of theεe εurface active agentε are thoεe deεcribed in, e.g., U.S. Patent Noε. 2,240,472, 2,831,766, 3,158,484, 3,210,191, 3,294,540 and 3,507,660, Britiεh Patent Noε. 1,012,495, 1,022,878, 1,179,290 and 1,198,450, U.S. Patent Noε. 2,739,891, 2,823,123, 3,068,101, 3,415,649, 3,666,478 and 3,756,828, Britiεh Patent No. 1,397,218, U.S. Patent Noε. 3,133,816, 3,441,413, 3,475,174, 3,545,974, 3,726,683 and 3,843,368. Belgium Patent No. 731,126, Britiεh Patent Noε. 1,138,514, 1,159,825 and 1,374,780, U.S. Patent Noε. 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 εaponin, nonionic εurfactantε εuch aε aliphatic esterε of polyhydric alcoholε, and an anionic εurfac- tant containing a εulfuric acid ester group. The photographic emulsion used in thiε invention can contain a diεperεion of a εynthetic polymer which is inεoluble or εlightly εoluble in water for the purpoεe of improving the dimenεional εtability, the development and the fixing and drying rateε. Examples of polymerε which can be uεed include polymerε compoεed of one or more alkyl acrylateε or methacrylateε, alkoxyalkyl acrylates or methacrylates, glycidyl acrylates or methacrylates, acyl or methacrylamide, vinyl eεterε (for example, vinyl acetate), acrylonitrile, olefinε and εtyrene, etc., and polymerε comprising a combination of the above deεcribed monomerε and acrylic acid, methacrylic acid, unεaturated dicarboxylic acidε, hydroxyalkyl acrylates or methacrylates or εtyreneεulfonic acid, etc. For example, thoεe compoundε deεcribed in U.S. Patent Noε. 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 Britiεh Patent Noε. 1,186,699 and 1,307,373, all incorporated by reference, can be uεed. A εuitable amount of the polymer rangeε from about 20 to 80% by weight baεed on the total weight of the binders. Since high-contraεt emulsions such as that used in this invention are suitable for the reproduction of line drawings and the dimensional stability iε of importance for εuch a purpoεe, it iε preferred to use the above-described polymer disperεion to be employed. In addition to the componentε of the photographic emulεionε and other hydrophilic colloid layers described above, it is appreciated that other conventional agents compatible with obtaining relatively high contraεt images can be present. For example, the photographic elements can contain developing agents (deεcribed below in connection with the proceεεing εtepε), development modifierε, plaεticizerε and lubricantε, coating aids, antistatic materialε, matting agentε, brightenerε and color materialε, theεe conventional materialε being illuεtrated in Paragraphs V, VIII, XI, XII and XVI of Research Diεclosure, December 1978 Item 17643, all incorporated by reference. Preferably, the photographic emulεion alεo containε anti-ageing agentε, " useful to prolong the shelf life of the emulεion. Suitable anti-ageing agentε (eεpecially for rhodium-doped emulεionε) include polyhydroxyεpiro-biε-indane aε diεcloεed in U.S. Patent No. 4,346,167 of E. Imatomi and preferably phenidone (up to 2 g/kg of emulεion) aε diεcloεed in U.S. Patent No. 2,751,297 of G. Hood. In forming photographic elements, the layers can be applied on photographic supports by various procedures, including immersion or dip coating, roller coating, reverse roll coating, air knife coating, doctor blade coating, gravure coating, spray coating, extruεion coating, bead coating, εtretch-flow coating and curtain coating. High speed coating uεing a pressure differential iε illustrated by Beguin U.S. Patent No. 2,681,294. Controlled variation in the presεure differential to facilitate coating εtartε iε illuεtrated by Johnson U.S. Patent No. 3,220,877 and to minimize splicing diεruptionε iε illuεtrated by Fowble U.S. Patent No. 3,916,043. Coating at reduced preεεureε to accelerate drying iε illuεtrated by Beck U.S. Patent No. 2,815,307. Very high εpeed curtain coating iε illuεtrated by Greiller U.S. Patent No. 3,632,374. Two or more layers can be coated simultaneouεly, aε illustrated by Russell U.S. Patent No. 2,761,791, Wynn U.S. Patent No. 2,941,898, Miller et al U.S. Patent No. 3,206,323, Bacon et al U.S. Patent No. 3,425,857, Hughes U.S. Patent No. 3,508,947, Herzhoff et al U.K. Patent No. 1,208,809, Herzhoff et al U.S. Patent No. 3,645,773 and Dittman et al U.S. Patent No. 4,001,024. In εimultaneouε multilayer coating varied coating hopperε can be uεed, aε illuεtrated by Ruεεell et al U.S. Patent No. 2,761,417, Ruεsell U.S. Patent Noε. 2,761,418 and 3,474,758, Mercier et al U.S. Patent No. 2,761,419, Wright U.S. Patent No. 2,975,754, Padday U.S. Patent No. 3,005,440, Mercier U.S. Patent No. 3,627,564, Timεon U.S. Patent Noε. 3,749,053 and 3,958,532, Jackεon U.S. Patent No. 3,933,019 and Jackεon et al U.S. Patent No. 3,996,885. Silver halide layerε can also be coated by vacuum evaporation, aε illuεtrated by Lu Valle et al U.S. Patent Noε. 3,219,444 and 3,219,451. The photographic emulsionε are coated on conventional εupportε which do not undergo εeriouε dimenεional changeε during proceεεing. Typical εuitable εupportε which can be uεed are a celluloεe acetate film, a polyεtyrene film, a polyethylene terephthalate film, a polycarbonate film, a laminate thereof, paper, baryta paper, paper coated on laminated with a hydrophobic polymer εuch aε polyethylene, polypropylene, etc. aε are commonly uεed for photographic light-εenεitive materialε. Tranεparent εupportε can be employed for certain end uεeε of the light-εenεitive material. Alεo, tranεparent εupports may be 33 colored by adding a dye or a pigment thereto aε deεcribed in SMPTE, 67, 296 (1958), or Cleare, U.S. Patent No. 3,822,13 (1984), incorporated by reference. Where the adheεion betwee the εupport and the photographic emulεion layer(ε) is inεuffi cient, a εubbing layer (an adheεive layer) that adhereε to bot the εupport and the photographic emulsion layer(s) can b employed. Alεo, in order to improve the adheεion, εurface of th support may be subjected to a preliminary proceεεing such a corona diεcharge, irradiation with ultraviolet light, flam treatment, etc. A suitable coating amount of silver iε about 0. g/m^ to about 10 g/m 2 of the εupport. The photographic elementε can be i agewiεe expoεed wit various forms of energy, which encompasε the ultraviolet an viεible (e.g., actinic) and infrared regionε of the electromag netic spectrum aε well aε electron beam and beta radiation, gamm ray. X-ray, alpha particle, neutron radiation and other forms o corpuscular and wavelike radiant energy in either noncoheren (random phase) formε or coherent (in phase) forms, as produced b laserε ("flash exposure"). Exposures can be monochromatic orthochromatic or panchromatic. Imagewiεe expoεureε at ambient elevated or reduced temperatureε and/or preεεures, including hig or low intensity exposureε, continuous or intermittent exposures exposure times ranging from minutes to relatively εhort duration in the millisecond to microsecond range and solarizing exposureε can be employed within the uεeful reεponεe rangeε determined b conventional εensitometric techniqueε, aε illuεtrated by T. H Jameε, The Theory of the Photographic Proceεε, 4th Ed., Macmil lan, 1977, Chapterε 4, 6, 17, 18 and 23, incorporated b reference. The photographic light-εenεitive material of thi invention can be photographically processed uεing known method and known proceεεing solutions. The processing temperatur uεually rangeε from about 18° to about 50 β C, but temperature lower than about 18 β C. or higher than about 50 β C. may be uεed. Thiε invention is particularly useful for the formation of a image by development in which a εilver image iε formed ( black-and-white photographic proceεεing). The developers used for black-and-white photographic procesεing preferably contain, aε a developing agent, aminophenolε (such aε N-methyl-p-aminophenol), 3-pyrazolidones (such as l-phenyl-3-pyrazolidone) , l-phenyl-3-pyrazolines, dihydroxybenzeneε (εuch aε hydroquinone) and other of the aforementioned developing agentε. Specific exampleε of the uεeful developing agentε include hydroquinone alone, hydroquinone pluε N-methyl-p-aminophenol, hydroquinone pluε 1 -pheny1-3-pyrazolidone , and hydroquinone pluε N-methyl-p-aminophenol pluε l-phenyl-3-pyrazolidone. Moreover, the developerε uεually contain a known antioxidant, an alkali agent, a pH buffer or the like and, if deεired, a diεεolving aid, a color toning agent, a development accelerator, a εurface active agent, an anti-foaming agent, a water εoftener, a hardener, a tackifier, etc., may be preεent. An anti-fogging agent (εuch as an alkali metal halide or benzotriazole) may be present in the developer. According to thiε invention, even when development is carried out uεing 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 about 11 to about 12.3. If the pH exceeds about 12.3, the developer iε unεtable even when a high concentration of εulfite ionε iε preεent, and it iε dif¬ ficult to maintain εtable photographic characteriεticε for more than 3 days under usual use conditionε. Fixing εolutionε having a compoεition generally employed in the art can be uεed in the preεent invention. Not only thioεulfateε and thiocyanateε but alεo organic εulfur compoundε known aε fixing agentε can be uεed aε fixing agentε in the preεent invention. Preferred exampleε of fixing agentε which can be uεed in the fixing εolution include water-εoluble thioεulfateε εuch as εodium thioεulfate, potaεεium thioεulfate, ammonium thioεulfate, etc., water-εoluble thiocyanateε εuch aε εodium thiocyanate, potasεium thiocyanate, ammonium thiocyanate, etc., water-εoluble organic diol fixing agentε containing an oxygen atom or a εulfur atom εuch aε 3-thia-l,5-pentanediol, 3,6-dithio-l,8-octanediol, 9-OXO-3,6,12,15-tetrathio-l,17-heptadecanediol, etc., wat εoluble sulfur-containing organic dibaεic acids and water-εolub εaltε thereof εuch aε ethyleneb ' iεthioglycollic-. acid and t εodium εalt thereof, etc., imidazolidimethioneε εuch methylimidazolidimethione, etc. Theεe agentε described in L. A.Maεon, Photographic Processing Chemistry, pageε 187 to 18 Focal Press (1966). A particularly preferred developing εyεtem in acco dance with the preεent invention containε a hydroquinone develo ing agent, a benzotriazole antifogging agent (developme restrainer), diethylamino-propanediol, εodium sulfite, and a modifier (preferably NaOH and/or Na 2 Cθ3) to adjust the pH to 11. ± 0.5. The most preferred developing εyεtem iε set forth in t Exampleε below. The preferred ethanedioic acid hydrazideε of t preεent invention are listed in Table I. Among them, the εe i oxamazideε 1-1, 1-2, 1-3 and 1-15 are particularly preferred. The compoundε of the preεent invention, "I", ar εyntheεized as described in U.S. Patent No. 4,686,167. The co Briefly, the reaction iε carried out at 60*-90*C in a appropriate εolvent εuch aε dimethyl formamide or pyridin without any catalyst being necessary. All compounds of Formul II can be synthesized using the foregoing scheme. Startin materials εuch as 2,4-dinitrobenzaldehyde; 2,6-dinitrobenzaldehyde; 2-nitrobenzaldehyde; 3-nitrobenzaldehyde; 4-nitrobenzaldehyde; rhodanine; rhodanine-3-acetic acid; and SUBSTITUTESHEET 36 5-nitroquinoline are commercially available from Eastman Kodak, Rochester, N.Y. and/or Aldrich Chemical, Milwaukee, Wise, and compounds II-3 and 11-25 are commercially available from Aπitec, Binghamtom, N.Y. The following exampleε are given to illuεtrate the present invention in more detail. However, the scope of the preεent invention iε not limited to theεe exampleε. EXAMPLE 1 (Syntheεiε) Compound II-2: 5 meta-nitrobenzylidene rhodanine To 507cc of dimethyl formamide (DMF) add 72 g of m- nitrobenzaldehyde followed by the addition of 60 g of rhodanine. Warm to diεεolve εolids 60-70 β C. Add slowly 50cc of pyridine. Heat to 80-70 β C with stirring for one hour. Cool to 20 β C, filter and wash with cool DMF. Disεolve cake in 507cc DMF (80-90 β C), filter. Cool to 20 β C, filter εolids, wash with DMF at 40 β C. Stir solidε in 900cc of methanol at room temperature for one hour. Filter, wash on funnel with an additional 450cc of methanol, dry. Analysis % C % H % N % S Theory 45.11 2.27 10.52 24.06 Found 45.39 2.37 10.21 23.73 Compound II-3: 5 meta-nitrobenzylidone rhodanine-3-acetic acid To 1000 cc of pyridine 166 g of m-nitrobenzaldehyde are added followed by 193 g of 3-carboxymethyl rhodanine. Heat is applied for 5 hours at 90-95 β C. The mixture iε then cooled and 4000 ml of methanol are added, iε then washed with methanol followed by acetone and ethyl ester and left to dry. The yield is 880 g. M.P. > 300, maximum n . ethanol. Compound II-4: 5 para-nitrobenzylidene rhodanine To 500 tc of dimethyl formamide (DMF) 72 g of p- nitrobenzaldehyde are added followed by addition of 60 g of rhodanine. The mixture is warmed to disεolve εolids to 60-70*C. Slowly 50 cc of pyridine are added and heated to 80-90"C for 1 hour while stirring. It is then cooled to 20"C, filtered and waεhed with cool DMF. The cake is diεsolved in 500 cc of εolids and washed with DMF at 40 β C. The εolidε are εtirred for 1 hou in 900 cc of methanol at room temperature, filtered and washed o funnel with the addition of 450 cc of methanol and left to dry. Maximum 371 nm in methanol. Compound II-6: 5 meta-nitrobenzylidene-3-hydroxy rhodanine To 500 cc of dimethyl formamide (DMF) 72 g of eta nitrobenzaldehyde are added followed by addition of 60 g of 3 hydroxyrhodanine (Aldrich). The mixture is warmed to dissolv solids to 60-70 β C. Slowly 50 cc of pyridine are added and heate to 80-90 β C for 1 hour while stirring. It iε then cooled to 20°C, filtered and washed with cool DMF. The cake is dissolved in 50 cc of DMF (80-90 β C), filtered hot, cooled to 20'C. The solid are filtered, washed with DMF at 40'C and εtirred in 900 cc o methanol for 1 hour in 900 cc of methanol at room temperature. Filtered and waεhed on funnel with the addition of 450 cc o methanol and left to dry. Maximum 373 nm in methanol. Compound II-9: 5T7-nitro-2-naphthylidene1-rhodanine To 500 cc of dimethyl formamide (DMF) 96 g of 7 nitro- 2-naphthaldehyde (Aldrich) are added followed by addition of 60 g of rhodanine. The mixture iε warmed to diεεolve εolidε to 60- 70"C. Slowly 50 cc of pyridine are added and heated to 80-90 β C for 1 hour while εtirring. It iε then cooled to 20 β C, filtered and waεhed with cool DMF. The cake iε diεεolved in 500 cc of DMF (80-90 β C) filtered hot, and then cooled to 20 β C. The εolidε are waεhed with DMF at 40"C, and εtirred for 1 hour under addition of 900 cc of methanol at room temperature, filtered and waεhed on funnel with the addition of 450 cc of methanol and then left to dry. Maximum 369 nm in methanol. EXAMPLE 2 A gelatino(εilver chlorobromoiodide) emulεion contain¬ ing approximately 90 percent chloride, 9 percent bromide and 1 percent iodide was prepared at 68 β C for 10 minutes by a standard double jet addition technique producing εilver halide grainε having an average εize of 0.30 micron. After removal of εoluble εaltε by a conventional method, the emulεion was chemically ripened uεing labile εulfur compoundε at 61 β C for 70 minutes. 38 This emulsion contained gelatin in the amount of 71.3 g per mole εilver halide. EXAMPLE 3 A gelatino(εilver bromide) emulεion was prepared at 65*C for 37 minutes by a controlled double jet addition technique while the pAg was maintained an 8.3. The average grain size of the εilver bromide cryεtalε waε 0.27 micron with a εize diεtribu- tion of 16%. After removal of the εoluble εaltε by conventional methods, the emulsion was chemically ripened using both labile εulfur and gold agentε at 65"C for 65 minuteε. Thiε εurface εensitized emulsion contained gelatin in the amount of 81.9 g per mole silver bromide. In the examples that follow, a comparison iε made between the preferred compoundε from Group I and II. Significant parameterε for compariεon include: a) relative mid εpeed b) gamma c) pepper level = arbitrary εcale from 1 (beεt) to 5 (worεt). (Any level below 4 iε acceptable.) A decreaεe in pepper from any unacceptable level to any acceptable level (e.g. from 4 to 3) iε conεidered εubstantial. EXAMPLE 4 The emulsion described in Example 3 was εplit into 250 g portionε. Each portion waε identically prepared for coating by the addition of an infrared εenεitizing dye (εubεtituted dicar- bocyanine) and εurfactant coating aidε (ethoxylated phenol). Variouε levels of compoundε of Formulas I and II were added as in Table A below. The finaled emulεionε were coated at 3.7 g εilver/m on a εubbed polyeεter film εupport along with a gelatin protective layer which contained formaldehyde, ethoxylated phenol εurfactant and a εilica matting agent. The exposed element waε proceεεed in an "exhausted" development chemiεtry (run through a table top proceεεor for 8 hourε at 90 β F) having the following compoεition (EDTA iε ethylene-diaminetetraacetate) As illustrated in the above test results, if Compoun I are added alone, gamma goes up but pepper also goes up. Pepp is substantially decreased with incorporation of about 1 10 mole Compound II/mole Ag. By contrast, neither sensitivity n gamma were substantially affected. The remaining Type I compounds can be anticipated yield comparable results when tested with the above and oth Type II compounds. The amount of compound II that could be used in t developing solution would be about 500-1000 times larger (p liter of solution) than in the photographic material. SUBSTITUTESHEET

Claims: 40 What is claimed is: 1. A silver halide photographic material comprising 1 radiation-senεitive εilver halide grainε capable of forming a 2 εurface-latent image, a binder, a dot quality-promoting amount of 3 at leaεt one compound of the Formula I, and a pepper-reducing 4 effective amount of at least one compound of the Formula II: 5 6 Y 00 "7 M fl II (I) 11 12 wherein: 13 X=-NR 5 R 6 , or -0R 7 14 R^ and R 2 are independently selected from the 15 group consisting of hydrogen, substituted and unsubεtituted alkyl 16 having up to 18 carbon atomε; εubstituted and unsubεtituted 17 cycloalkyl, phenyl and naphthyl; 18 R3 is selected from the group conεiεting of 19 hydrogen, εubstituted and unsubstituted benzyl provided that R3 20 is hydrogen when neither R j _ and R 2 are hydrogen; wherein R^ and 21 R 2 or R^ and R3 can be linked together for form a heterocyclic 22 ring syεtem with the ring having 3-10 carbon atomε; 23 R4 iε a divalent aromatic group with the two 24 valenceε being ortho- or para- to each other εaid group being 25 εubεtituted or unεubεtituted; 26 R5, Rg and R are independently εelected from the 27 group conεiεting of hydrogen, εubεtituted or unεubεtituted alkyl -28 having up to 12 carbon atomε; εubεtituted or unsubεtituted 29 cycloalkyl, phenyl and naphthyl; wherein R5 and Rg can be linked 30 to form a hetercyclic ring εyεtem with the ring containing 3-10 31 atomε; 32 Y is selected from the group conεiεting of εulfur 33 and oxygen atomε; 34 n iε zero or one; provided that n = 1 when Y is R'ι is selected from the group consisting of ben- zothiazole, quinoline, indolenine, nitrobenzothiazole, ben- zotriazole and rhodanine nuclei, each of which may be εubstituted or unsubstituted, and m is an integer between 0 and 6 inclusive; and wherein εaid amount of εaid Formula II compound is inεufficient to εubstantially decrease senεitivity of εaid emulεion. 2. A εilver halide photographic material aε in claim 1, wherein εaid at leaεt one compound repreεented by the Formula I iε preεent in an amount of 1x10 " to lxl0~ ol per mol of εilver halide and εaid at least one compound represented by the Formula II is preεent in an amount of 5xl0~ to 1.0 mol per mol of silver halide. 3. A silver halide photographic material aε in claim 1, wherein εaid at leaεt one compound represented by the Formula I iε preεent m an amount of 1x10 -5 to 4x10-1 mol per mol of εilver halide and said at least one compound represented by the Formula II is present in an amount of from 1x10 -5 to 5x10-4 mol per mol of εilver halide. 4. The material of claim 1 wherein both εaid com- poundε are incorporated in εaid emulεion. 5. The material of claim 1 wherein at leaεt one of εaid compounds is incorporated in another hydrophilic layer of εaid material. 6. A εilver halide photographic material aε in claim 1, wherein εaid at least one compound represented by the Formula I and said at least one compound represented by the Formula II, are independently incorporated in at least one of a εilver halide emulεion layer, a protective layer, an intermediate layer, a filter layer, and an antihalation layer. 7. A proceεε for forming a εuper-high contraεt negative image, compriεing imagewiεe expoεing and developing a εilver halide photographic material compriεing a support having provided thereon at least one silver halide emulsion layer, said emulεion layer or another layer or the developer εolution uεed to develop εaid image εaid material containing a dot-quality promot- ing amount of at leaεt one compound repreεented by the Formula I and a pepper-reducing effective amount of a compound of the Formula II: Y 00 R χ (NR 2 )nCN-R 4 -NHNHCCX (I) 3 wherein: X=-NR 5 R 6 , or -0R 7 R^ and R 2 are independently εelected from the group conεiεting of hydrogen, εubεtituted and unεubεtituted alkyl having up to 18 carbon atomε; εubεtituted and unεubεtituted cycloalkyl, phenyl and naphthyl; R3 is εelected from the group conεiεting of hydrogen, εubεtituted and unεubεtituted benzyl provided that R3 iε hydrogen when neither R^ and R 2 are hydrogen; wherein R j and R 2 or R^ and R3 can be linked together for form a heterocyclic ring εyεtem with the ring having 3-10 carbon atomε; R4 iε a divalent aromatic group with the two valenceε being ortho- or para- to each other εaid group being εubεtituted or unεubstituted; R5, Rg and R7 are independently εelected from the group conεiεting of hydrogen, εubεtituted or unεubεtituted alkyl having up to 12 carbon atomε; εubεtituted or unεubεtituted cycloalkyl, phenyl and naphthyl; wherein R5 and Rg can be linked to form a hetercyclic ring εyεtem with the ring containing 3-10 atomε; Y iε εelected from the group conεiεting of εulfur and oxygen atomε; n iε zero or one; provided that n = 1 when Y iε εulfur; wherein R' iε εelected from the group conεiεting of ben- zothiazole, quinoline indolenine, nitrobenzothiazole, ben- zotriazole and rhodanine, each of which may be εubεtituted or unεubεtituted, and m iε an integer between 0 and 6 inclusive; and wherein εaid amount of εaid Formula II compound iε insufficient to substantially decrease sensitivity of εaid emulsion. 8. A process for forming a super-high contrast negative image according to claim 7, wherein said developing iε carried out with a developer containing a εulfite ion in an amount of from 0.4 mol/l to 2.5 mol/l and having a pH of 10.5 to 12.3. 9. The proceεε of claim 7 wherein εaid Formula I compound iε preεent in the developing εolution. 10. The proσeεε of claim 7 wherein εaid Formula II compound iε preεent in the developing εolution. 11. The proceεε of claim 7 wherein both εaid Formula I and εaid Formula II compounds are both present in the photographic material. 12. A proceεε for forming a εuper high-contraεt image compriεing imagewiεe exposing and developing a εilver halide containing photographic material compriεing a εupport having provided thereon at leaεt one εilver halide emulεion layer, at leaεt one of εaid emulεion layer, another layer and the developer uεed to develop εaid image, εaid material containing a dot- quality promoting amount of a hydrazine or hydrazide compound and a pepper-reducing effective amount of a compound of the Formula II wherein R' j iε εelected from the group conεiεting of ben- zothiazole, quinoline, indolenine, nitrobenzothiazole, ben- zotriazole and rhodanine, each of which may be εubεtituted or unεubstituted, and m iε an integer between 0 and 6 inclusive; and wherein εaid amount of εaid Formula II compound iε inεufficient to εubεtantially decreaεe εenεitivity of εaid emulεion. 13. The proceεε of claim 12 wherein εaid image iε a negative image. 14. The process of claim 13 wherein said emulsion is of the εurface latent image negative-working type. 15. The process of claim 14 wherein εaid Formula II compound is incorporated in the photographic material. 16. The procesε of claim 14 wherein said Formula II compound iε incorporated in the developer. 17. The proceεε of claim 15 wherein εaid Formula II compound iε 5-metanitrobenzylidene rhodanine. 18. The proceεε of claim 16 wherein εaid hydrazide compound iε 1-[4,-(3"-ethylthioureido)-phenyl]-5-methyl- εemioxamazide, and iε alεo incorporated in the photographic material. 19. The proceεε of claim 18 wherein the amount of εaid Formula II compound iε within the range of about 1x10"^ to about 5x10""^ mol per mol of εilver halide. 20. The procesε of claim 19 wherein the amount of said εemioxamazide iε within the range of about 1x10"^ to about 4xl0~ mol per mol of εilver halide. 21. The material of claim 1 wherein εaid Formula I compound is Compound 1-2 and said Formula II compound is 5-meta nitrobenzylidene rhodanine. 22. The material of claim 21 wherein said Formula I and εaid Formula II compoundε are incorporated in εaid emulεion in amountε within the range of 1x10"^ to 4x10"" " - for the compound of Formula I and the range of lxl0~ 5 to 5x10"^ for the compound of Formula II.

Inventors: ALTAVILLA ALEXANDER, ALTAVILLA, ALEXANDER
Applicants: INT PAPER CO, INTERNATIONAL PAPER COMPANY
Application year: 1990
Main classification: G03C1
IPC codes: G03C1