JPH0377974B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to improving the whiteness of photographic materials, and more particularly to improving the whiteness of photographic materials by incorporating a fluorescent brightener into a photographic layer coated on a support. The photographic layer referred to in the present invention includes a silver halide emulsion layer, subbing layer, intermediate layer, over layer, and backing layer of a silver halide photographic light-sensitive material, and an image receiving layer, subbing layer, intermediate layer of a diffusion transfer photographic material, Including overlayer, backing layer, etc. In general, the technology of improving the whiteness of photographic materials by incorporating a fluorescent brightener into a photographic layer containing gelatin as the main component is well known and has already been used in the industry as a means of increasing the commercial value of photographic materials. There is. Fluorescent whitening agent uses ultraviolet light (300-400nm)
and part of the energy of this absorbed light is 400
It has the property of emitting blue or violet light of ~500 nm. Generally, photographic materials use gelatin, so they have a yellowish tinge, and the emitted light is between 420 and 450 nm.
An optical brightener having a maximum wavelength of . Fluorescent brighteners such as stilbene derivatives, benzidine derivatives, diphenyl derivatives, benzothiazole derivatives, benzoxazole derivatives, coumarin derivatives, and pyrazoline derivatives are known, but stilbene derivatives in particular are water-soluble and commercially available. It has been widely used in photographic materials. Fluorescent brighteners used in photographic layers must have sufficient whiteness even when added in small amounts, must not affect photographic properties (sensitivity, tone, fog, developability, etc.), and must be used during photographic processing (especially during water washing). ), strict properties are required, such as no leakage, and little change in whiteness of the photographic material before and after processing. Stilbene derivative optical brighteners, which are commonly used in photographic materials, have poor dyeing properties for gelatin, and have the disadvantage that they leak out during photographic processing (especially during water washing), resulting in insufficient whiteness. . Various attempts have been made to eliminate these drawbacks. For example, Tokuko 34-7127, Tokuko 39-
22065, Special Publication 43-22882, Special Publication 44-2522, Special Publication 47-
26900 and Japanese Patent Publication No. 47-49028, polyvinylpyrrolidone, poly-N-vinyl-5-methyl-2-oxazolidinone, N-vinylpyrrolidone and styrene,
Copolymers such as vinyl acetate, N-morpholinoalkylalkenoylamide polymers, dialdehyde starch and aminoguanidine reaction products, and optical brighteners such as partially urethanized polyvinyl alcohol are water-soluble polymeric substances that have good adsorption properties. How to add, also JP 44-11941 JP 45-24068, JP 46-8518, JP JP
No. 48-27692, Japanese Patent Publication No. 48-28220, etc., attempts have been made to use a method in which a water-insoluble optical brightener is dispersed or to polymerize the optical brightener. However, polyvinylpyrrolidone and poly-N-vinyl-5-methyl-
Addition of a water-soluble polymeric substance such as 2-oxazolidinone affects the setting temperature and viscosity of the gelatin solution, and often also affects the physical properties of the gelatin film, particularly the hardness and glossiness. Furthermore, the method of dispersing the optical brightener or the method of polymerizing it is expensive. JP-A-54-94318 uses acid-treated gelatin to prevent the optical brightener from leaking into the processing solution, but this method requires the use of acid-treated gelatin in the photographic layer. subject to certain restrictions. In addition, regarding photographic properties, stilbene derivative fluorescent brighteners can improve the photographic properties of silver halide emulsions (sensitivity,
(fogging, tone, etc.). In particular, fogged direct positive silver halide photographic emulsions are extremely sensitive to additives due to the nature of the emulsion, and are therefore easily affected by optical brighteners. Consideration is required. The present inventors have developed a stilbene derivative optical brightener, which has been conventionally used in silver halide negative emulsions with relatively little effect on photographic properties, in fogged direct positive silver halide photographic emulsions. When photographic characteristics were investigated, most of them affected the photographic characteristics, and in particular, the decrease in sensitivity was remarkable. In the present invention, the fogged direct positive silver halide photographic light-sensitive material is a silver halide photographic light-sensitive material consisting of fogged silver halide grains and an electron acceptor. Refers to a silver halide photographic light-sensitive material in which the fog is formed to an appropriate degree, the fog nuclei are destroyed by exposure, and a reversed image is obtained by development. In general, stilbene derivative optical brighteners have the following general formula: Z is a water-soluble group such as a sulfonic acid group or a carboxyl group, and X and Y are various substituents such as a hydrogen atom, a hydroxyl group, an aryloxy group, an alkoxy group, a halogen atom, a heterocyclic group, an alkylthio group, an arylthio group, These include an amino group, an alkylamino group, an arylamino group, and the like. For reference, here are a few compounds: There are many descriptions in U.S. Pat. Many are also listed in the Dye Handbook (edited by the Organic Synthetic Chemistry Association) and the Color Index. A first object of the present invention is to provide a photographic material that has excellent whiteness even after undergoing various photographic processes. The second object is to provide a fogged direct positive silver halide photosensitive material having excellent whiteness. The present inventors have investigated various stilbene derivative fluorescent brighteners to achieve the above object, and have found that certain stilbene derivative fluorescent brighteners are extremely effective for the purpose of the present invention. Ta.
That is, the object was achieved by incorporating a fluorescent whitening agent having the following general formula into a photographic layer using gelatin. (In the formula, R ₁ R ₂ represents an alkyl group having 1 to 4 carbon atoms, and M represents hydrogen or an alkali metal.) The optical brightener of the present invention has excellent dyeing properties for gelatin, and has various Because there is little leakage from the photographic layer during photographic processing, there is very little change in whiteness before and after processing, and even when added to a fogged direct positive photographic emulsion, there is no change in its photographic properties. It has an excellent property of having no influence. The optical brightener of the present invention is synthesized in accordance with the synthesis of general stilbene derivative optical brighteners, and is easily synthesized by a general synthetic method. Mata Tokukoaki
52-41366, 51-13797, the synthesis method is described in detail. Next, the gelatin used in the present invention is an alkali-treated gelatin, an acid-treated gelatin, or a modified gelatin thereof, which is generally used in photographic layers, and the type of gelatin is not particularly limited. Alkali-processed gelatin includes bone and skin gelatin, desalted gelatin, gelatin with a calcium content of 2000 PPM or less compared to dry gelatin, low molecular weight gelatin, high jelly-strength gelatin with a young extraction number of 280 g or more, and acid-processed gelatin. is bone and skin gelatin, demineralized gelatin, calcium content is higher than dry gelatin.
Gelatin jelly strength of 2000 PPM or less High jelly strength gelatin of 280 g or more, low isoelectric point gelatin (for example, acid-treated gelatin with an isoelectric point of 5.5), and modified gelatin include phthalated gelatin, carbamylated gelatin, etc. Even if different types of gelatin are used, the effects of the present invention will not be impaired. In addition to gelatin, the photographic layer contains polymeric compounds such as polyvinyl alcohol and its derivatives and copolymers, acrylamide and its derivatives and copolymers, polyvinylpyrrolidone and its derivatives and copolymers, and maleic anhydride copolymers (such as styrene-copolymers). Maleic anhydride copolymer, ethylene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, vinyl acetate
maleic anhydride copolymers, etc.) and their derivatives, acrylic acid and its derivatives and copolymers, emulsion polymers (e.g. styrene, butadiene, methyl acrylate, ethyl acrylate, butyl acrylate, ethylene, methyl methacrylate, Latexes of ethyl methacrylate, butyl methacrylate, acrylic acid, vinyl acetate, etc. alone or copolymers thereof, etc.), heated products of polyvinyl alcohol and maleic anhydride copolymers, etc. may also be present. Further, natural polymer compounds such as carboxymethyl cellulose, hydroxyethyl cellulose, pullulan, etc. may be used in combination with gelatin. The method of adding the optical brightener of the present invention is to add it in an aqueous solution during the manufacturing process so that it is contained in an amount of 5 mg or more per 1 m ² of at least one photographic layer, and the photographic layer to which it is added is not limited. The whitening effect is greater when it is contained in the top layer. The content of the fluorescent whitening agent is not particularly limited and may be increased or decreased as appropriate depending on the desired degree of whiteness. Moreover, the pH at the time of addition is not particularly limited, and can be added within the range of 2 to 13. Photographic materials to which the present invention can be applied include silver halide photographic materials and image-receiving materials for diffusion transfer photographic materials, and are particularly suitable for fogged direct positive silver halide photographic materials. The properties of fogged direct positive silver halide photosensitive materials are different from those of silver halide negative photosensitive materials.
The properties of the fogged emulsion (stability of fog nuclei, aging, sensitivity to additives, etc.) are particularly sensitive compared to negative emulsions, and emulsion technology different from negative emulsion technology is required. . The optical brightener of the present invention can be added to an emulsion without impairing the properties of the fogged emulsion. The fogged direct positive silver halide photographic emulsion of the present invention can be prepared using known techniques such as JP-A No. 56-36646,
56-36647 and 56-39534 using the type of silver halide, grain size, fogging agent, noble metal, dye sensitizer, etc. Further, silver halide negative photographic emulsions and image-receiving layers of diffusion transfer photographic materials can also be manufactured using techniques well known in the photographic industry. The photographic layer of the photographic material of the present invention contains various conventionally used photographic additives (for example, surfactants, plasticizers, developing agents such as hydroquinone and phenidone, matting agents, antistatic agents, thickeners). , stabilizers, etc.). The photographic layer can also be hardened with a suitable hardening agent. Hardeners include aldehyde compounds, methylol compounds, triazine compounds, activated vinyl compounds, and carbodiide compounds. As the support for the photographic layer of the photographic material of the present invention,
Examples include cellulose acetate film, polyethylene terephthalate film, polyethylene, polypropylene laminated paper, paper, baryta paper, etc., with polyethylene laminated paper or baryta paper being particularly suitable. The photographic material of the present invention can be subjected to known photographic processing (developing, fixing, bleaching, washing), and
Even if the above-mentioned high-temperature rapid treatment is performed, the effects of the present invention are not impaired. Next, embodiments of the present invention will be described, but of course the present invention is not limited thereto. Example 1 Acid- and alkali-treated gelatin aqueous solution (PH6~
Add a 2% aqueous solution of an optical brightener to 6.5), and further add a hardening agent and a coating aid, and add 3 g/m ² of gelatin and an optical brightener to photographic polyethylene laminated paper.
After coating and drying at 20mg/m ² and 30mg/m ²
Samples were prepared by heating at 50°C for one day. As optical brighteners, those having the following structural formula according to the present invention and Compound 1.2 described in the specification were added as a comparison. Optical brightener of the present invention The fluorescence intensity of the samples before and after treatment was compared. Processed with SKD-72 developer for 90 seconds (20℃), 2%
After treatment with acetic acid stop solution for 30 seconds and EKF-5 fixer for 5 minutes, the sample was washed with running water for 10 minutes and dried. Fluorescence intensity was measured with a Hitachi 203 fluorescence spectrometer. Table 1 summarizes the results of the examples. In Table 1, the fluorescence intensity is shown as relative fluorescence intensity.

【table】

[Table] * Acid-treated gelatin isoelectric point 8-9
Table 1 shows that Compounds 1 and 2 significantly leak out during processing, but the optical brightener of the present invention shows extremely little leakage. Example 2 Silver nitrate aqueous solution, potassium bromide and potassium iodide aqueous solution were added to an alkali-treated gelatin aqueous solution of pH 2.5 with strong stirring at 60°C over 80 minutes while controlling PAg to 7.4 to give 2.5 mol%. A cubic monodisperse silver iodobromide gelatin emulsion containing silver iodide and an average grain size of approximately 0.25 microns is prepared. This emulsion is desalted by a flocculation method using salts or a gelatin flocculant. After redissolving this emulsion and adding gelatin to make the weight ratio of gelatin to silver nitrate 1, PH = 6.5 PAg = 6.2
Adjusted to. After adding 0.2 mg/mol Ag of thiourea dioxide and aging at 65℃ for 45 minutes,
mg/mol Ag was added and aged for 45 minutes. After this, adjust the pH from 5.0PAg to 8.6 and use the dye below.
300mg/mol Ag and pinacryptol yellow 200mg/mol
After adding Ag, a hardening agent and a surfactant were added, the mixture was divided into seven equal parts, a fluorescent brightener was added as shown in Table 2, and the mixture was coated on polyethylene laminate paper and dried. The amount of silver applied is 2
g/m ² , and the amount of coated gelatin is 3 g/m ² . The sample was heated at 40°C for 4 days and then treated in the same manner as in Example 1.
Changes in photographic characteristics were expressed as relative sensitivity.

【table】

[Table] As is clear from Table 2, even when the optical brightener of the present invention is added to a fogged direct positive emulsion, it does not affect the photographic properties at all, and the fogged emulsion has excellent whiteness. I was able to make positive photographic materials directly.

Claims (1)

[Scope of Claims] 1. A silver halide photosensitive material for direct positive use, characterized in that a water-soluble optical brightener having the general formula shown below is contained in a photographic layer using gelatin. (In the formula, R ₁ and R ₂ represent an alkyl group having 1 to 4 carbon atoms, and M represents hydrogen or an alkali metal.)