Silver halide photographic light-sensitive material

Abstract: A silver halide photographic light-sensitive material optically sensitized in red wavelength region. The light-sensitive material comprises a support having thereon a silver halide emulsion layer containing an optical sensitizing dye represented by the following formula I; wherein Z is a group of atoms necessary to form a thiazole ring, a benzothiazole ring, a naphthothiazole ring, a selenazole ring, a benzoselenazole ring or a naphthoselenazole ring; R₁, R₂, R₃, R₄ and R₅ are independently a hydrogen atom, a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, provided that at least three of groups represented by R₁, R₂, R₃, R₄ and R₅ each has an organic group having a water-solubilizing group. The light-sensitive material is excellent in storage stability and lowered color stain after processing.

Description: The present invention relates to a red-sensitive silver halide photographic light-sensitive material low in residual color stain with improved storage stability. As spectral sensitizing dyes for a silver halide photographic light-sensitive material, cyanine dyes and merocyanine dyes are primarily used, and many proposals have been made for techniques to sensitize light-sensitive material spectrally from the visual wavelength region to the infrared wavelength region. Recently, in the fields of graphic arts and medical care, the use of silver halide photographic light-sensitive materials with light sources which emit infrared light, for example, laser beams, is becoming widespread. Particularly in the field of printing, various facsimile films and color scanner films are used, and a helium-neon gas laser having an output wavelength of 632.8 nm and a light-emitting diode LED having an output wavelength of 650 to 700 nm is mainly used as a light source. These silver halide photographic light-sensitive materials need a high spectral sensitizing capability in the red wavelength regions as well as a high storage stability and a capability of preventing residual color stain after development. Following the recent technical tendency toward a more rapid and simple processing and lower replenishing amounts, removal of residual color stains is liable to be insufficient and, as a result, the performance and commercial value of light-sensitive materials are impaired. As conventional techniques to minimize the residual color of light-sensitive materials, U.S. Pat. Nos. 2,493,747 and 2,526,632 for example, disclose merocyanine dyes to which a water-solubilizing group is introduced; further, use of trinuclear merocyanine dyes is proposed in Japanese Pat. O.P.I. Pub. No. 143242/1990, and use of trinuclear merocyanine dyes having two water-solubilizing groups is disclosed in Japanese Pat. O.P.I. Pub. No. 171135/1991, wherein all the exemplified compounds contain carboxyl groups as water-solubilizing groups. However, none of these techniques is sufficient in preventing residual color stains and they all have the problem that light-sensitive materials are liable to vary in sensitivity or to cause fog in the course of storage. Therefore, a new approach has been required to solve these problems. It is an object of the invention to provide a silver halide photographic light-sensitive material having a high sensitivity in the red wavelength region, excellent in storage stability and free from residual color stains after processing. According to the present invention there is provided a silver halide photographic light-sensitive material comprising a support having thereon a silver halide emulsion layer containing an optical sensitizing dye represented by the following Formula [1]: wherein Z represents a group of atoms necessary to complete a thiazole, benzothiazole, naphthothiazole, selenazole, benzoselenazole or naphthoselenazole ring; R 1 , R 2 , R 3 , R 4 and R 5 are independently a hydrogen atom, substituted or unsubstituted alkyl or aryl group; provided that at least one of the groups represented by R 1 , R 2 , R 3 , R 4 and R 5 is a -(CH 2 ) n SO 3 M group, a -C 6 H 4 SO 3 M group, a -CH 2 C 6 H 4 SO 3 M group, a -CH 2 -CH=CH-CH 2 SO 3 M group or a -CH 2 CH(SO 3 M)CH 3 group; and at least two of the groups represented by R 1 , R 2 , R 3 , R 4 and R 5 are a -CH 2 COOH group, a -(CH 2 ) n COOM group, a -C 6 H 4 COOM group, a -CH 2 C 6 H 4 COOM group, a -CH 2 -CH=CH-CH 2 COOM group, a -(CH 2 ) 2 SO 2 NHC 6 H 5 group, and/or a -CH 2 CH 2 CONH 2 group, wherein n is an integer of 2 to 4 and M is hydrogen, an alkali metal, an ammonium group or an organic amine. In the above Formula [1], at least three of R 1 to R 5 represent organic groups each having a water-solubilizing group; the term "water-solubilizing groups" meaning a group having a negative π value in the Hansch method used in the so-called structure-activity correlation which deals with the relationship between structure of a compound and its bioactivity. Details of the Hansch method can be seen in J. Med. Chem., 16, 1207 (1973) and ibid. 20,304 (1979). At least two of these water-solubilizing groups are ionizable in water and have a pKa of 4 to 11, and at least one of these water-solubilizing groups or organic groups has a pKa not larger than 4. Thus excellent spectral sensitivity is obtained and residual color stains can be reduced. The water-solubilizing groups having a pKa of 4 to 11 are: -(CH 2 ) n COOM, -C 6 H 4 COOM, -CH 2 C 6 H 4 COOM, -CH 2 -CH=CH-CH 2 COOM, -(CH 2 ) 2 SO 2 NHC 6 H 5 , -CH 2 CH 2 CONH 2 . The water-solubilizing groups having a pKa not larger than 4 are: -(CH 2 ) n SO 3 M, -C 6 H 4 SO 3 M, -CH 2 -CH=CH-CH 2 SO 3 M, -CH 2 CH(SO 3 M)CH 3 . In the above formulas, n represents an integer of 2 to 4, and M represents a hydrogen atom, an alkali metal atom, an ammonium group or an organic amine. In Formula [1], examples of the alkyl substituents for R 1 to R 5 other than those mentioned above include those having up to 8 carbon atoms such as methyl, ethyl, propyl, butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, heptyl and octyl groups which may be straight chained or branched (when not cyclic). Preferred examples of the substituents for substituted alkyl groups include a halogen atom such as chlorine, bromine or fluorine atom, a hydroxyl group, a monocyclic or dicyclic aryl group having 6 to 12 carbon atoms. This aryl group, for example a phenyl group is optionally substituted by an alkyl group with 4 or less carbon atoms, a nitro group or a halogen atom, an alkoxycarbonyl group with 4 or less carbon atoms such as ethoxycarbonyl group, an acyl group having 4 or less carbon atoms such as acetyl group or benzyl group whose benzene ring is substituted by a nitro group or a halogen atom, and an alkoxy group having 4 or less carbon atoms such as methoxy or ethoxy group. Preferred aryl groups are phenyl or naphthyl groups which are optionally substituted. Examples of the substituents include an alkyl group having 4 or less carbon atoms such as methyl, ethyl or isopropyl group. The thiazole, benzothiazole, naphthothiazole, selenazole, benzoselenazole or naphthoselenazole ring represented by Z in Formula 1 is optionally substituted by a group usually used in a spectral sensitizing dye. Preferred substituents are, for example, the same alkyl group as that represented by any one of the above R 1 to R 5 , a substituted alkyl group, an aryl group, a halogen atom and, further, a sulfonamido group such as a sulfonamido group substituted with an alkyl group having not more than 4 carbon atoms, a carbamoyl group such as a non-substituted carbamoyl, methyl carbamoyl or phenyl carbamoyl group. The following are typical examples of the sensitizing dyes represented by Formula [1]. The above merocyanine dyes can be synthesized according to the methods described in U.S. Pat. Nos. 2,493,747 and 2,656,351 or methods analogous to them. The dye of the invention is preferably added to an emulsion in an amount of 10 -6 mol to 10 -2 mol, more preferably 10 -5 mol to 10 -3 mol, per mol of silver contained in the emulsion. The dye may be added to the emulsion at any time during silver halide grain formation to coating, preferably at a time between completion of chemical ripening and coating of the emulsion. The silver halide emulsion used in the invention (hereinafter referred to as the silver halide emulsion or simply as the emulsion) may use any of the silver halides usually employed in a silver halide emulsion, such as silver bromide, silver iodobromide, silver iodochloride, silver chlorobromide and silver chloride. But preferred are monodispersed emulsions comprising silver halide grains having a grain size less than 3 µm, especially from 0.1 to 1 µm. The silver halide emulsion may use various techniques and additives known in the art. For example, there may optionally be contained in the silver halide emulsion or in backing layers various chemical sensitizers, toning agents, hardeners, surfactants, thickeners, plasticizers, lubricants, development controlling agents, UV absorbents, anti-irradiation dyes, heavy metals and matting agents in various manners. Further, the silver halide emulsion and the backing layer may contain polymer lattices. Suitable supports for the silver halide photographic light-sensitive material of the invention include film or sheets of acetylcellulose, nitrocellulose, polyesters such as polyethylene terephthalate or polyolefines such as polyethylene; baryta paper; paper coated with polyolefine; and glass or metal sheets. These supports can optionally be subjected to surface treatment when necessary. The silver halide photographic light-sensitive material of the invention can be processed, after exposure, by various of the usual methods. Suitable black-and-white developers are alkaline solutions containing developing agents such as hydroxy benzenes, aminophenols or aminobenzenes and may contain sulfites, carbonates, bromides or iodides of an alkali metal. EXAMPLES Example 1 Preparation of Silver Halide Emulsion A silver chloroiodobromide emulsion, comprising 62 mol% silver chloride, 0.5 mol% silver iodide, the other was silver bromide, was prepared by the double-jet method. To the emulsion were added potassium hexabromorhodate and potassium hexachloroiridate in amounts of 8 × 10 -8 mol/mol Ag and 8 × 10 -7 mol/mol Ag, respectively, during the mixing process from the time when grains had grown to 5% of the intended final average size to the time when the grains had grown to the intended final average size. The emulsion obtained was desalted by the usual flocculation method using a modified gelatin treated with phenylisocyanate and then dispersed in gelatin. Subsequently, fungicides (A), (B) and (C) described later were added thereto, so that an emulsion comprising cubic monodispersed grains having an average grain size of 0.30 µm and a coefficient of variation of 10% were obtained. The coefficent of variation is defined as σ/ r × 100(%), in which σ is an standard deviation of grain sized distribution and r is an averaged grain size. After adding citric acid and potassium bromide, the emulsion was chemically ripened at 60 °C to the maximum sensitivity by the addition of chloroauric acid and sodium thiosulfate, then the ripening was stopped by adding 1-phenyl-5-mercaptotetrazole and 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene in amounts of 50 mg/mol AgX and 1 g/mol AgX, respectively. Preparation of Emulsion Coating Solution To this emulsion were added separately the comparative compounds and the exemplified compounds of the invention in amounts of 2 × 10 -4 mol per mol of silver halide as shown in Table 1. After adding sodium dodecylbenzenesulfonate as a surfactant and sodium 2,4-dichloro-6-hydroxytriazine as a hardener in the usual amounts, the coating solution so-obtained was uniformly coated on a subbed polyethylene terephthalate film so as to give a silver coating weight of 4 g/m 2 and a gelatin coating weight of 3 g/m 2 . The coated sample was exposed for 10 -6 seconds through an optical wedge by use of a He-Ne laser as light source. Then, it was processed in a Photomechanical Automatic Processor GR-27 (Konica Corp.) using the following developer and fixer under the following conditions. The processed sample was subjected to sensitometry using an Optical Densitometer Konica PD A-65. In Table 1, the sensitivity is given in a value relative to the sensitivity of sample 1 which was set at 100, and the residual color density is a residual color density measured with the above densitometer immediately after the processing. A residual color density of 0.05 in the table is at a level of almost no residual color, and a value of 0.09 or above is at a level at which practical problems arise. Processing Conditions The processing conditions were as follows: As the use of developper, composition A and composition B were dissolved in this order in 500 ml of water, and then water was added to make the total volume 1 liter. Fixer (Composition A) Ammonium thiosulfate (72.5% W/V aqueous solution) 230 ml Sodium sulfite 9.5 g Sodium acetate trihydrate 15.9 g Boric acid 6.7 g Sodium citrate dihydrate 2 g Acetic acid (90% W/W aqueous solution) 8.1 ml (Composition B) Deionized water 17 ml Sulfuric acid (50% W/W aqueous solution) 5.8 g Aluminium sulfate (8.1% W/W aqueous solution as Al 2 O 3 ) 26.5 g At the use of developper, composition A and composition B were dissolved in this order in 500 ml of water, and then water was added to make the total volume 1 liter. The pH of this fixer was about 4.3. Processing Conditions Process Temperature Time Developing 34 °C 15 sec Fixing 34 °C 15 sec Washing ordinary temp. 10 sec Drying 40 °C 10 sec Each processing time includes the crossover time till the start of a following process. Sample No. Sentitizing Dye Sensitivity Residual Color Remarks 1 Comparison(1) 100 0.10 Comparison 2 Comparison(2) 80 0.09 Comparison 3 Comparison(3) 90 0.09 Comparison 4 Comparison(4) 100 0.10 Comparison 6 Exemplified I-3 105 0.05 Invention 7 Exemplified I-4 90 0.06 Invention 9 Exemplified I-7 110 0.06 Invention 11 Exemplified I-13 105 0.06 Invention 13 Exemplified I-17 90 0.05 Invention 14 Exemplified I-18 105 0.05 Invention 15 Exemplified I-19 105 0.05 Invention As is apparent from Table 1, the samples of the invention have sensitivities equal to those of the comparative samples and much higher residual color preventing capabilities. Example 2 Dyes of the invention and those for comparison were added as shown in Table 2 to the emulsion ripened under the optimum conditions in Example 1. Preparation of Emulsion Layer Coating Solution To this emulsion were added, per mol of silver halide, 4 g of hydroquinone, 2 g of potassium bromide, 10 g of polymer latex P1 of the following structure, 250 mg of 5-nitroindazole and 2 g of styrene-maleic acid copolymer and, further, usual amounts of 1N aqueous solution of sodium hydroxide, sodium dodecylbenzenesulfonate as an auxiliary and sodium salt of 2,4-dichloro-6-hydroxyazine as a hardener. Preparation of Coating Solution for Emulsion Protective Layer As coating weights per m 2 , there were added 5.5 mg of 1-phenyl-4-hydroxymethyl-3-pyrazolidone and 25 mg of monodispersed silica having an average particle size of 3 µm to an aqueous solution of 1.1 g of gelatin. Further, there were added an aqueous solution of sodium 1-decyl-2-(3-isopentyl)succinate-2-sulfonate, S-1 and citric acid as coating aids, and formalin as a hardener. Preparation of Backing Layer Coating Solution As coating weights per m 2 , there were added, to an aqueous solution containing 2.0 g of gelatin, 100 mg of the following water-soluble dye III-1, 25 mg of III-2, 100 mg of III-3, 100 mg of III-4, 350 mg of polymer latex P-1, 60 mg of styrene-maleic acid copolymer, 150 mg of colloidal silica, sodium dodecylbenzenesulfonate as a coating aid, glyoxal, and 55 mg of E-2. Preparation of Coating Solution for Backing Protective Layer As coating weights per m 2 , there were added 12 mg of sodium 1-decyl-2-(3-isopentyl)succinate-2-sulfonate and a dispersion of monodispersed polymethylmethacrylate with an average particle size of 5.5 µm to an aqueous solution containing 1.0 g of gelatin. After stirring, there were further added glyoxal as a hardener, and sodium salt of 2,4-dichloro-6-hydroxytriazine. Preparation of Samples After performing a corona dischage treatment on one side of a polyethylene terephthalate film support at an energy of 15 W/m 2 ·min, the backing layer coating solution and the coating solution for protecting the backing layer were coated thereon. After performing a corona dischage treatment on the other side of the support at an energy of 15 W/m 2 ·min, an emulsion layer was formed thereon so as to give a silver coating weight of 4.0 mg/m 2 and a gelatin coating weight of 1.7 mg/m 2 , followed by the formation of a protecting layer for the emulsion layer. Accelerated Aging Test The light-sensitive material sample obtained as above was divided into two parts. One part was stored for 3 days under conditions of 23 °C and 50% RH for use as a fresh sample. The other part was conditioned for 8 hours under conditions of 23 °C and 50% RH and enclosed in a moisture-proof bag in a lapped form. Then, it was subjected to forced deterioration at 55 °C for 3 days, so that a sample for the accelerated aging test was obtained. These samples were each exposed for 10 -5 second through an optical wedge and an interference filter of 488 nm and then were processed as in Example 1. The sensitivity and the residual color density in the unexposed portion of these samples shown in Table 2 were determined in the same manner as in Example 1. The sensitivity is expressed in a value relative to the sensitivity of sample 22 stored for 3 days at 23 °C and 50% RH, which was set at 100. As apparent from Table 2, the samples of the invention have a smaller sensitivity change due to aging and have less residual color.

Claims: A silver halide photographic light-sensitive material comprising a support having thereon a silver halide emulsion layer containing an optical sensitizing dye represented by the following formula I: wherein Z is a group of atoms necessary to complete a thiazole ring, a benzothiazole ring, a naphthothiazole ring, a selenazole ring, a benzoselenazole ring or a naphthoselenazole ring; R 1 , R 2 , R 3 , R 4 and R 5 are independently a hydrogen atom, a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, provided that at least one of the groups represented by R 1 , R 2 , R 3 , R 4 and R 5 is a -(CH 2 ) n SO 3 M group, a -C 6 H 4 SO 3 M group, a -CH 2 C 6 H 4 SO 3 M group, a -CH 2 -CH=CH-CH 2 SO 3 M group or a -CH 2 CH(SO 3 M)CH 3 group; and at least two of the groups represented by R 1 , R 2 , R 3 , R 4 and R 5 are a -CH 2 COOH group, a -(CH 2 ) n COOM group, a -C 6 H 4 COOM group, a -CH 2 C 6 H 4 COOM group, a -CH 2 -CH=CH-CH 2 COOM group, a -(CH 2 ) 2 SO 2 NHC 6 H 5 group, and/or a -CH 2 CH 2 CONH 2 group, wherein n is an integer of 2 to 4 and M is hydrogen, an alkali metal, an ammonium group or an organic amine. The light-sensitive material of claim 1, wherein the ring represented by Z is a benzothiazole ring or a naphthothiazole ring. The light-sensitive material of claim 1 or 2, wherein said silver halide emulsion layer comprises silver halide grains having a silver chloride content of not less that 30 mol%. The light-sensitive material of claim 3, wherein said silver halide emulsion layer comprises silver halide grains having a silver chloride content of from 50 mol % to 90 mol %. The light sensitive material of any one of the preceding claims wherein the substituted or unsubstituted alkyl group represented by R 1 , R 2 , R 3 , R 4 or R 5 is a straight or branch chained or cyclic alkyl group with up to eight carbon atoms. The light sensitive material of any one of the preceding claims wherein the substituted or unsubstituted alkyl group represented by R 1 , R 2 , R 3 , R 4 or R 5 is a methyl, ethyl, propyl, butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, heptyl or octyl group. The light sensitive material of any one of the preceding claims wherein the dye is added to the silver halide emulsion layer in an amount of 10 -6 mol to 10 -2 mol per mole of silver contained in the emulsion. The light sensitive material of claim 7 wherein the dye is added to the silver halide emulsion layer in an amount of 10 -5 mol to 10 -3 mol per mole of silver contained in the emulsion. The light sensitive material of any one of the preceding claims wherein the silver halide emulsion used in the silver halide emulsion layer is a monodispersed emulsion comprising silver halide grains having a grain size less than 3µm. The light sensitive material of claim 9 wherein the silver halide emulsion layer comprises silver halide grains having a grain size of from 0.1 to 1µm.

Inventors: ITO HIROHIDE, KATO MARIKO, SANPEI TAKESHI, ITO, HIROHIDE, KATO, MARIKO, SANPEI, TAKESHI, ITO, HIROHIDE, OF KONICA CORPORATION, KATO, MARIKO, OF KONICA CORPORATION, SANPEI, TAKESHI, OF KONICA CORPORATION
Applicants: KONISHIROKU PHOTO IND, KONICA CORPORATION
Application year: 1992
Main classification: G03C1
IPC codes: C09B23, G03C1