JPH10509251A - Photothermographic element with improved adhesion between layers. - Google Patents

Abstract

  (57) [Summary] Spectral sensitized photothermal comprising a support having on at least one surface thereof a photothermographic composition comprising a polyvinyl acetal binder, a non-photosensitive silver source, a reducing agent for silver ions and infrared-sensitive silver halide grains A photographic silver halide element, wherein the composition comprises a non-polyvinyl acetal polymer component or a metallic soap other than an organic acid silver soap dispersed in an amount of from 0.3 to 20% by weight of the polyvinyl acetal (particularly halogen). Wherein the polymer component has a stronger adhesive strength to polyester than polyvinyl acetal, and the polymer is a polyvinyl acetal. Element that may be present as a separate phase within.

Description

Description: FIELD OF THE INVENTION The present invention relates to radiation-sensitive photothermography comprising silver halide, a source of reducible silver, a reducing agent for silver ions and a binder. The invention relates to a photothermographic element having an emulsion coating that exhibits improved adhesion to the element, particularly to adjacent layers, especially to polymer film substrates and supports. BACKGROUND OF THE INVENTION Silver halide containing photothermographic imaging materials that are thermally developed and not liquid developed (ie, heat developable photographic elements) have been known in the art for many years. The materials are also known as "dry silver" compositions or emulsions and generally comprise (a) a photosensitive material that generates silver atoms upon irradiation, (b) a non-photosensitive source of reducible silver, (c) A) a reducing agent for silver ions (ie, a developer), eg, silver ions in a non-photosensitive silver source, and (d) a support coated with a binder. The photosensitizer is generally a photographic silver halide that must be in catalytic proximity to a non-photosensitive source of reducible silver. Since the catalytic approach requires a close physical relationship between the two materials, the silver atoms (also known as silver specks, clusters or nuclei) are exposed to the light of the photographic silver halide. Alternatively, when produced by exposure, the nuclei can catalyze the reduction of a reducible silver source. Elemental silver (Ag ⁰ ) Has long been understood to be a catalyst for the reduction of silver ions, in which photosensitive silver halide is placed in a number of different forms in catalytic proximity to a non-photosensitive source of reducible silver. There is. For example, catalytic access may be by partial metathesis of a halogen-containing source and a reducible silver source (see, eg, US Pat. No. 3,457,075); By precipitation (see, for example, U.S. Pat. No. 3,839,049); and by other methods closely related to light-sensitive photographic silver halide and non-photosensitive sources of reducible silver. The non-photosensitive source of reducible silver is a substance containing silver ions. Preferred non-photosensitive sources of reducible silver are typically silver salts of long chain aliphatic carboxylic acids having 10 to 30 carbon atoms. Silver salts of behenic acid or a mixture of acids of equivalent molecular weight are generally used. Other organic acids or salts of organic substances (eg, silver imidazolates) have also been proposed. U.S. Pat. No. 4,260,677 discloses the use of complexes of inorganic or organic silver salts as non-photosensitive sources of reducible silver. In both photographic and photothermographic emulsions, exposure of photographic silver halide to light produces small clusters of silver atoms (Ag °). The distribution of the image aspects of this cluster is known in the art as a latent image. This latent image is generally not visible by ordinary means. As such, the photosensitive emulsion must be further processed to produce a visible image. This is caused by the reduction of silver ions that are in catalytic proximity to silver halide grains (ie, the latent image) having clusters of silver atoms. The reducing agent for organic silver salts (often called "developer") may be a substance capable of reducing silver ions to metallic silver, preferably an organic substance. At high temperatures, a non-photosensitive source of reducible silver (eg, silver behenate) is reduced by a silver ion reducing agent in the presence of a latent image. This produces a negative black and white image of the silver element. Conventional photographic developers such as methyl gallate, hydroquinone, substituted hydroquinones, sterically hindered phenols, catechol, pyrogallol, ascorbic acid and ascorbic acid derivatives are useful, but provide highly reactive photothermographic formulations. And a tendency to cloud during preparation and coating of photothermographic elements. As a result, sterically hindered bisphenol reducing agents are conventionally preferred. Since the visible image in a black and white photothermographic element is made exclusively of silver elements (Ag °), the amount of silver in the emulsion cannot be easily reduced without reducing the maximum image density. However, reducing the amount of silver is often desired because it reduces the cost of raw materials used in the emulsion and / or improves performance. For example, bluing agents may be incorporated to enhance the color of the silver image of the photothermographic element. Another way to increase the maximum image density of photographic and photothermographic emulsions without increasing the amount of silver in the emulsion layer is to incorporate dye-forming or dye-releasing materials into the emulsion. Upon imaging, the dye-forming or dye-releasing material is oxidized to simultaneously form a dye and a reduced silver image in the exposed areas. In this way, a black-and-white silver image enhanced by the dye can be produced. Imaging technology has long acknowledged that photothermographic and thermal transfer technologies are quite different from photographic technologies. Photothermal and thermal transfer elements are significantly different from conventional silver halide photographic elements that require wet development. In photothermographic and thermal transfer imaging elements, the visible image is created by heat as a result of the reaction of a developer incorporated within the element. Heat is essential for development and usually temperatures above 100 ° C are required. In contrast, conventional wet-developed photographic imaging elements require processing in aqueous developing baths (eg, developing and fixing baths) to provide a visible image, and development is usually It is performed at a moderate temperature (for example, 30 to 50 ° C.). In photothermographic elements, only a small amount of silver halide is used to capture light, and different forms of silver (eg, silver behenate) are used to generate the image thermally. That is, silver halide is supplied as a catalyst for developing a non-photosensitive source of reducible silver. In contrast, conventional wet-developed black-and-white photographic elements use only some forms of silver (e.g., silver halide) that are themselves converted to silver images during development. Further, photothermographic elements require as much as one hundredth of the silver halide per unit area of silver halide used in conventional wet developed silver halide. Photothermographic systems use a non-photosensitive silver salt, such as behenic acid, which is associated with the developer when developing the latent image. In contrast, photographic systems do not use non-photosensitive silver salts directly in the image forming process. As a result, images in photographic black-and-white elements are mainly obtained by silver halide, whereas images in photothermographic elements are mainly produced by reduction of a non-photosensitive silver source (silver behenate). In photothermographic and thermal transfer elements, all of the "chemicals" of the system are incorporated into the element itself. For example, photothermographic and thermal transfer elements incorporate a developer (i.e., a reducing agent for a non-photosensitive source of reducible silver) into the element, whereas conventional photographic elements do not. The incorporation of a developer into the photothermographic element may enhance the formation of "cloudiness" when coating the photothermographic emulsion as compared to the photographic emulsion. Even in so-called instant photography, the developer chemicals are physically separated from the silver halide until development is desired. Great efforts have been made in the preparation and manufacture of photothermographic and thermal transfer elements to minimize haze formation during coating, storage and post-development aging. Similarly, in a photothermographic element, unexposed silver halide remains inherent after development and the element must be stabilized against further development. In contrast, silver halide is removed from the photographic element after development to avoid further imaging (i.e., the fixing step). In photothermographic and thermal transfer elements, the binder can vary widely, and a number of binders are available when preparing the element. In contrast, photographic elements are almost exclusively limited to hydrophilic colloidal binders such as gelatin. Because photothermographic and thermal transfer elements require development, they pose another consideration and represent a completely different problem in manufacturing and use. In addition, the effects of additives (eg, stabilizers, anti-fogging agents, speed enhancers, sensitizers, supersensitizers, etc.) that are believed to directly affect the imaging process can be attributed to photothermography. It can vary depending on whether it is incorporated into a photographic or thermal transfer element or in a photographic element. The difference between photothermographic elements and photographic elements is that Imaging Processes and Materials, Nebulette, 8th ed .; J. Sturge et al .; Van Nostrand * Van Nostrand Reinhold: New York, 1989; Chapter 9 and Unconventional Imaging Processes; Ed. E. Brinckman et al .; The Focal Press. (The Focal Press): London and New York: 1978; pages 74-75. It is important that the layers of the photothermographic element adhere closely to each other. This is usually done by selecting components in adjacent layers that have good adhesion, or by treating the support layer for better adhesion (eg, flash light source, corona discharge, flame treatment, etc.), or This is achieved by using a primer layer. The fact that polyester (polyethylene terephthalate or polyethylene naphthalate) film supports and polyvinyl butyral are preferred binders for photothermographic emulsion layers avoids altering the above components to enhance adhesion. SUMMARY OF THE INVENTION The present invention is directed to a photothermographic imaging system, including those that are spectrally sensitized to red or infrared, to provide high adhesion between an emulsion layer and an adjacent polymer binder layer or polymer support layer. Describes a structure having improved adhesion between layers. According to the present invention, there is provided a spectrally sensitized photothermographic silver halide element comprising a support layer having a photothermographic composition on at least one surface, wherein the composition comprises a polyvinyl acetal binder, A composition comprising a photosensitive silver source, a reducing agent for silver ions and infrared-sensitive silver halide particles, wherein the composition is 1) not a polyvinyl acetal, but a dissolved (solution) or dispersed polymer component, or 2) an organic Metallic soaps other than the acid silver soaps (especially not usually the long chain fatty acids usually contained in silver halide based photothermographic elements), wherein the dispersion and / or solution is incorporated into the composition. , Polyvinyl acetal in an amount of 0.5 to 20% by weight, and the adhesive strength to the polymer component polyester film is higher than that of polyvinyl acetal. Element is provided. Here, “emulsion layer” means a layer of a photothermographic element containing a photosensitive silver salt (eg, silver halide) and a silver source material. Here, the term "photothermographic element" means a structure comprising at least one photothermographic emulsion layer and a support, a top coat layer, an image receiving layer, a blocking layer, an antihalation layer, an undercoat layer, and the like. For the purposes of the present invention, the infrared region of the spectrum is defined as 750-1400 nm, the visible region of the spectrum is defined as 400-750 nm, and the red region of the spectrum is defined as 640-700 nm. Preferably, the red region of the spectrum is between 650 and 700 nm. DETAILED DESCRIPTION OF THE INVENTION Pending U.S. patent applications Ser. Nos. 08 / 072,153 (filed Nov. 23, 1993) and 08 / 239,984 (filed May 9, 1994) include, for example, Most photothermographic elements having an antihalation layer, silver halide grains having an average grain size of less than 0.10 .mu.m, and infrared supersensitization leading to infrared photothermographic articles satisfying the requirements in medical or graphic arts laser recording applications. Are described. Commercially available products have an undesirable adhesion of the emulsion layer containing polyvinyl butyral as the sole binder to the support. This is particularly noticeable in high density image areas where a significant amount of the adhesion promoting silver soap has been consumed and converted to metallic silver and fatty acids, and the coating is easily stripped from the polyester support. Conventional photothermographic elements contain polyvinyl butyral as a first component (first trip) to provide cohesion of the silver-containing emulsion layer. Polyvinyl butyral is also assumed to be a component due to the adhesion of the coating to the polyester support. In recent years, we have found that a 100% polyvinyl butyral coating has little adhesion to polyester, suggesting that polyvinyl butyral is not the only component due to the adhesion of the silver-containing emulsion layer to the polyester support. did. We have subsequently found that coated films consisting of a mixture of polyvinyl butyral and silver soap adhere strongly to polyester. That is, it is clear that the adhesion of the emulsion layer to the support is provided by the mixture of polyvinyl butyral and silver soap in the silver-containing emulsion layer. This hypothesis is substantiated by the observation that the adhesion of the silver-containing emulsion layer to the support is significantly lower in high density image areas than in low density image areas or untreated film. The addition of resins and / or metallic soaps that promote adhesion to the silver layer significantly improves the adhesion of the silver layer to the support and is readily observed in dense image areas where adhesion is poor. Addition of a resin that promotes adhesion to the photosensitive layer (silver halide containing layer) can obviously improve the adhesion of the emulsion layer to the support layer (with or without a primer layer). The resin particles that promote adhesion are halogenated by blending two different resins that are not stable in a single phase (eg, using polyvinyl butyral as a first binder for a photothermographic layer containing silver halide). When generated within the silver halide layer, binders such as polyester resins (eg, PE2200 polyester), polyvinyl acetate, resins, etc., separate from the blend as particles dispersed within the polyvinyl butyral phase. The grains formed during this preparation were found to have a tendency to deposit, contact or adhere to the support (or a primer layer on the support) when the silver halide layer containing the above substances was coated on the support. . The grains have a size that is significantly smaller than the thickness of the silver halide containing layer and tend to remain immersed or buried in said layer so that they do not adversely affect the refractive pattern of the surface of the topcoat layer. Help to make. The grains may have an average size which is believed to be on the order of 1/10 to 2/3 of the thickness of the silver halide containing layer. Granular soaps that were evaluated to improve the adhesion of the silver layer to the polyester were magnesium stearate and zinc stearate. Photosensitive Silver Halide As noted above, the present invention includes photosensitive silver halide in photothermographic structures. The photosensitive silver halide can be a photosensitive silver halide such as silver bromide, silver iodide, silver chloride, silver iodobromide, silver iodobromochloride, silver bromochloride and the like. The photosensitive silver halide can be added to the emulsion layer in any manner as long as the photosensitive silver halide is placed in catalytic proximity to the organic silver compound supplied as the source of reducible silver. Examples of the silver halide include a cube, an octahedron, a rhombic dodecahedron, an orthorhombic, a tetrahedron, and other polygonal shapes, but are not limited thereto. May be epitaxially grown. Tabular grains are undesirable and, in fact, are the least preferred crystalline for use in the photothermographic elements of this invention. Narrow grain size distributions of just tabular grains (e.g., aspect ratios of 5: 1 or more) cannot be readily provided by existing techniques using preferred grain sizes of less than 0.10 [mu] m in average diameter. U.S. Pat. No. 4,806, representing "tabular" paired flat particles, referred to as tabular grains, having a grain thickness of less than 0.5 .mu.m and a mean grain diameter of less than 0.3 and having an aspect ratio of 2: 1 or more. There are particles referred to in the art as "plate-like", "plate-like" or "sigma" particles, whose aspect ratio can be less than 5: 1, as disclosed in U.S. Pat. The grains have a higher trapping surface area and volume ratio in the silver halide grains (e.g., higher than the coating weight of the grains, as in U.S. Pat. Nos. 4,425,425 and 4,425,426). (Projected area) does not include the conceptual properties of the original disclosure of tabular grains, and as tabular or tabular grains, as defined by the term simply extending the coverage area Within the skill of the expert It is not obvious. The silver halide grains may have a uniform ratio throughout the halide, for example, having a continuously varying, graded halide content of silver bromide and silver iodide. Alternatively, it may be of the core-shell type with a separate core of one halide ratio and a separate shell of another halide ratio. Core-shell silver halide grains useful in photothermographic elements and methods for their preparation are described in the following co-pending U.S. patent application Ser. No. 08 / 199,114, filed Feb. 22, 1994. The silver halide can be prepared ex situ (ie, preformed) and mixed with the organic silver salt in a binder before being used to prepare the coating solution. Silver halide can be preformed, for example, by the means of U.S. Pat. No. 3,839,049. For example, it is effective to blend the silver halide and the organic silver salt using a homogenizer for a long time. Such materials are often referred to as "preformed emulsions". A method for preparing the silver halide and the organic silver salt and a method for blending them are described in Research Disclosure, 1978, Item 17029; U.S. Pat. 076,539; and JP-B Nos. 13224/74, 42529/76, and 17216/75. It is desirable in the practice of this invention to use preformed silver halide grains of less than 0.10 μm in the infrared sensitized photothermographic material. Preferably, the number average particle size of the particles is between 0.01 and 0.08 μm, especially between 0.03 and 0.07 μm, most preferably between 0.04 and 0.06 μm. Iridium-doped silver halide grains and iridium-doped core-shell silver halide grains as disclosed in pending U.S. patent applications Ser. Nos. 08 / 072,153 and 08 / 239,984. It is also preferred to use. The preformed silver halide emulsion, when used in the materials of this invention, is unwashed or can be washed to remove soluble salts. In the latter case, the soluble salt is, for example, described in U.S. Pat. Nos. 2,618,556, 2,614,928, 2,565,418, and 3,241,969. According to the procedures described in U.S. Pat. No. 5,059,878 and U.S. Pat. No. 2,489,341, they can be removed by cooling and extraction or the emulsion can be coagulated and washed. It is also effective to use an in situ process (ie, a process in which a halogen-containing compound is added to an organic silver salt to partially convert the silver of the organic silver salt to silver halide). The light-sensitive silver halide used in the present invention is used in an amount of about 0.005 to about 0.5 mol, preferably about 0.01 to about 0.15 mol, especially about 0.1 mol, per mol of non-photosensitive reducible silver salt. .03 to 0.12 mole. The silver halide used in the present invention may be chemically and spectrally processed in a manner similar to that used to sensitize conventional wet developable silver halide or heat developable photographic materials known in the art. I can sensitize. For example, it may be a compound containing sulfur, selenium, tellurium or the like or a compound containing gold, platinum, palladium, ruthenium, rhodium, iridium, etc., a reducing agent such as tin halide or the like, or a chemical enhancer such as a combination thereof. It can be chemically sensitized by a sensitizer. Details of this procedure can be found in TH The James of The Theory of the Photographic Process, 4th Edition, Chapter 5, pages 149-160. Have been described. Suitable chemical sensitization procedures are also described in U.S. Pat. Nos. 1,623,499 [Shepard], 2,399,083 [Waller], and 3,297,477. [McVeigh] and 3,297,446 [Dunn]. The addition of a sensitizing dye to the photosensitive silver halide is provided to provide high sensitivity to visible light and infrared light by spectral sensitization. That is, the photosensitive silver halide can be spectrally sensitized using various known dyes that spectrally sensitize silver halide. Non-limiting examples of sensitizing dyes that can be used include cyan dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes, holopolar cyanine dyes, hemicyanine dyes, styryl dyes, and hemioxanol dyes. Of these dyes, cyanine dyes, merocyanine dyes, and complex merocyanine dyes are particularly useful. An appropriate amount of sensitizing dye added is generally about 10 to about 10 moles per mole of silver halide. ^-Ten -10 ^-1 Mole, preferably about 10 ^-8 -10 ^-3 Range of moles. Supersensitizers It is often desirable to use supersensitizers to increase the speed of the photothermographic element to a maximum level and further enhance infrared sensitivity. While any supersensitizer that enhances infrared sensitivity can be used, preferred supersensitizers are described in pending US patent application Ser. No. 07 / 846,919, and include heteroaromatic mercapto compounds (I) or Heteroaromatic disulfide compound (II): Ar-SM (I) Ar-SS-Ar (II) (wherein M represents a hydrogen atom or an alkali metal atom). In the supersensitizers (I) and (II), Ar represents an aromatic or fused aromatic ring containing one or more of nitrogen, sulfur, oxygen, selenium or tellurium atoms. Preferably, the heteroaromatic ring is benzimidole, naphthoimidazole, benzothiazole, naphthothiazole, benzoxazole, naphthoxazole, benzoselenazole, benzotellurazole, imidazole, oxazole, pyrazole, triazole, thiadiazole, tetrazole, triazine, pyrimidine, pyridazine , Pyrazine, pyridine, purine, quinoline or quinazolinone. However, other heteroaromatic rings are within the scope of the invention. Examples of the preferred heteroaromatic ring include halogen (for example, Br and Cl), hydroxyl, amino, carboxy, alkyl (for example, having 1 or more carbon atoms, preferably 1 to 4 carbon atoms) and alkoxy (for example, It may be substituted with a substituent selected from the group consisting of 1 or more carbon atoms, preferably 1 to 4 carbon atoms). Preferred supersensitizers are 2-mercaptobenzimidazole, 2-mercapto-5-methylbenzimidazole and 2-mercaptobenzothiazole. The supersensitizer is generally used in the emulsion layer in an amount of at least 0.001 mole per mole of silver. Usually, the range is between 0.001 and 1.0 mole of compound per mole of silver, preferably between 0.01 and 0.3 mole of compound per mole of silver. Non-photosensitive reducible silver source material The non-photosensitive reducible silver source that can be used in the present invention can be a material containing a reductant silver ion source. Preferably, it is a silver salt that is relatively light stable, but forms a silver image when heated above 80 ° C. in the presence of an exposed photocatalyst (such as silver halide) and a reducing agent. Silver salts of organic acids, particularly silver salts of long-chain aliphatic carboxylic acids, are preferred. The chains typically have 10 to 30 carbon atoms, preferably 15 to 28 carbon atoms. Suitable organic silver salts include silver salts of organic compounds having a carboxyl group. Examples include silver salts of aliphatic carboxylic acids and silver salts of aromatic carboxylic acids. Preferred examples of the aliphatic carboxylic acid silver salt include silver behenate, silver stearate, silver oleate, silver laurate, silver caprate, silver myristate, silver palmitate, silver maleate, silver fumarate, and tartaric acid. Examples include silver, silver furoate, silver linoleate, silver butyrate, and silver camphorate, and mixtures thereof. A silver salt that can be substituted with a halogen atom or a hydroxyl group can also be used effectively. Preferred examples of silver salts of aromatic carboxylic acids and other compounds containing a carboxyl group include silver benzoate, substituted silver benzoate (for example, silver 3,5-dihydroxybenzoate, silver o-methylbenzoate, m-methyl Silver benzoate, silver p-methylbenzoate, silver 2,4-dichlorobenzoate, silver acetamidobenzoate, silver p-phenylbenzoate, etc.), silver gallate, silver tannate, silver phthalate, silver terephthalate, Silver salicylate, silver phenylacetate, silver pyromellitate, silver salts of 3-carboxymethyl-4-methyl-4-thiazoline-2-thione as described in U.S. Pat. No. 3,785,830, And silver salts of aliphatic carboxylic acids containing a thioether group as described in U.S. Pat. No. 3,330,663. A silver salt of a compound containing a mercapto group or a thione group or a derivative thereof can be used. Preferred examples of the above compounds include silver salts of 3-mercapto-4-phenyl-1,2,4-triazole, silver salts of 2-mercaptobenzimidazole, silver salts of 2-mercapto-5-aminothiadiazole, Silver salt of thioglycolic acid such as silver salt of-(2-ethylglycolamide) benzothiazole, silver salt of S-alkylthioglycolic acid (wherein the alkyl group has 12 to 22 carbon atoms), dithioacetic acid Silver salt of dithiocarboxylic acid, silver salt of thioamide, silver salt of 5-carboxyl-1-methyl-2-phenyl-4-thiopyridine, silver salt of mercaptotriazine, silver of 2-mercaptobenzoxazole Salts, silver salts as described in U.S. Pat. No. 4,123,274 (e.g., 1,2,4, such as silver salts of 3-amino-5-benzylthio-1,2,4-thioazole). -Melka Thiones such as silver salts of derivatives of putthioazole), silver salts of 3- (2-carboxyethyl) -4-methyl-4-thioazoline-2-thione as disclosed in U.S. Pat. No. 3,201,678. And silver salts of the compounds. Silver salts of acetylene can also be used. Silver acetylides are described in U.S. Pat. Nos. 4,761,361 and 4,775,613. Furthermore, a silver salt of an imino group-containing compound can be used. Preferred examples of the compound include silver salts of benzotriazole and its derivatives (for example, silver methylbenzotriazole and silver 5-chlorobenzotriazole), as described in US Pat. No. 4,220,709. And silver salts of 2,4-triazole, and silver salts of imidazole and imidazole derivatives. It has also proven convenient to use silver half soap. A preferred example of a silver half soap is an equimolar blend of silver behenate and behenic acid having a silver analysis of about 14.5% and prepared by precipitation from a commercially available aqueous solution of sodium behenate. Transparent sheet materials made from a transparent film backing require a transparent coating. For this purpose, silver behenate full soap containing up to about 4 or 5% free behenic acid and having a silver analysis of about 25.2% can be used. The methods used to make silver soap dispersions are well known in the art and are described in Research Disclosure, April 1983, pp. 22812, and October 1983, pp. 23419, and U.S. Pat. No. 3,985,565. The silver halide and non-photosensitive reducible silver source material that form the starting point for development must be catalytically close, ie, "reactive association". “Catalytic proximity” or “reactive association” means that the substances should be in the same layer, in adjacent layers, or in layers separated from each other by an intermediate layer less than 1 μm thick Means It is preferable that the silver halide and the non-photosensitive reducible silver source material are contained in the same layer. According to the present invention, a preformed silver halide containing photothermographic emulsion can be sensitized with a chemical sensitizer, or a spectral sensitizer as described above. The reducing silver source material generally comprises from about 5% to about 70% by weight of the emulsion layer. It is preferably included on a basis of about 0 to about 50% by weight of the emulsion layer. Non-photosensitive reducing agent for reducing silver generating source The reducing agent for the organic silver salt may be a substance capable of reducing silver ions to metallic silver, preferably an organic compound. Conventional photographic developers (eg, phenidone, hydroquinone, and catechol) are useful, but sterically hindered phenol reducing agents are preferred. The photothermographic element used in this invention containing a reducing agent for the non-photosensitive source of reducible silver is preferably substantially free of water at a temperature of about 80 to about 250 ° C for about 1 second to about 2 minutes. Thermal development after or concurrently with imagewise exposure under conditions that do not include a black and white silver image in either the exposed or unexposed areas containing the exposed photosensitive silver halide. A wide range of reducing agents include amide oximes (eg, phenylamido oxime, 2-thienylamidooxime, and p-phenoxyphenylamidooxime), azines (eg, 4-hydroxy-3,5-dimethoxybenzaldehyde azine); Combinations of carboxylic acid aryl hydrazides and ascorbic acid (eg, combinations of ascorbic acid and 2,2′-bis (hydroxymethyl) propionyl-β-phenylhydrazide); polyhydroxybenzene and hydroxylamine, reductone and / or hydrazine [ For example, hydroquinone and bis (ethoxyethyl) hydroxylamine, piperidinohexose reductone or formyl-4-methylphenylhydrazine, phenylhydrooxamic acid, p-hydroxyphenylhydro Combinations with hydroxamic acids such as oxamidic acid and o-alanine hydrooxamic acid]; combinations of azines with sulfonamidophenols (eg, phenothioazines with 2,6-dichloro-4-benzenesulfonamidophenol); α-cyanophenylacetic acid derivatives (eg, α-cyano-2-methylphenylacetate, α-cyano-phenylacetate); 2,2′-dihydroxy-1-binaphthyl, 6,6′-dibromo-2,2 Bis-o-naphthols such as'-dihydroxy-1,1'-binaphthyl and bis (2-hydroxy-1-naphthyl) methane; combinations of bis-o-naphthol with 1,3-dihydroxybenzene derivatives (eg, 2,4-dihydroxybenzophenone or 2,4-dihydroxyacetophenone); 5-pyrazolone (eg, 3-methyl- -Phenyl-5-pyrazolone); reductones represented by dimethylaminohexose reductone, anhydrodihydroaminohexose reductone and anhydrodihydropiperidone hexose reductone; sulfamidophenol reducing agents (for example, 2,6 -Dichloro-4-benzenesulfonamidophenol and p-benzenesulfonamidophenol); indane-1,3-dione such as 2-phenylindan-1,3-dione and the like; 2,2-dimethyl-7-t- Chromans such as butyl-6-hydroxychroman; 1,4-dihydropyridines such as 2,6-dimethoxy-3,5-dicarbethoxy-1,4-dihydropyridine, bisphenols [for example, bis (2-hydroxy-3 -t-butyl-5-methylphenyl) methane), 1,1-bis (2-hydroxy-3,5-dimethylphenyl)- 3,5,5-trimethylhexane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 4,4-ethylidene-bis (2-tert-butyl-6-methylphenol) and 2,2- Bis (3,5-dimethyl-4-hydroxyphenyl) propane]; ascorbic acid derivatives (eg, 1-ascorbyl palmitate, ascorbyl stearate; unsaturated aldehydes and ketones; certain 1,3-indandiones; It is disclosed in a dry silver system containing 3-pyrazolidone (phenidone). The reducing agent should be present as 1 to 10% by weight of the imaging layer. In a multilayer structure, when a reducing agent is added to a layer other than the emulsion layer, the higher the ratio (about 2 to 15%), the more desirable there is a tendency. Optical Dye Forming or Dye Emitting Substance The reducing agent for the reducible silver source may be a compound that can be oxidized, directly or indirectly, to form or release the dye. A photothermographic element for use in the invention containing an optical dye-forming or dye-releasing material is treated with water, preferably at a temperature of from about 80 ° C to about 250 ° C (176 to 482 ° F) for about 1 to about 2 minutes. Thermal development after or simultaneously with imagewise exposure under substantially free conditions yields a black and white silver image in either the exposed or unexposed areas containing the exposed photosensitive silver halide. Leuco dyes are one of the dye-releasing substances that form dyes when oxidized. Leuco dyes that can be oxidized with silver ions to form a visible image can be used in the present invention. Leuco dyes that are pH sensitive and oxidizable can be used but are not preferred. Leuco dyes that are only sensitive to pH changes are not included in the category of dyes useful in the present invention because they cannot be oxidized to a colored form. Here, the "leuco dye" or "blocked leuco dye" is generally a colorless or very pale dye, and a dye capable of forming a colored image when the leuco or blocked leuco dye is oxidized to a dye form. In a reduced form. That is, blocked leuco dyes (ie, blocked dye releasing compounds) absorb more strongly than dyes in the visible region of the electromagnetic spectrum. The resulting dye is imaged directly on the sheet on which the dye is formed or, if used with a dye-receiving or image-receiving layer, as it diffuses through the emulsion and intermediate layers, onto the image-receiving layer. Is prepared. Representative types of leuco dyes that can be used in the photothermographic element of the present invention include chromogenic leuco dyes (eg, indoaniline, indophenol or azomethine leuco dyes); see US Pat. No. 3,985,565. Imidazole leuco dyes as described [eg 2- (3,5-di-t-butyl-4-hydroxyphenyl) -4,5-diphenylimidazole]; U.S. Pat. No. 4,563,415; Dyes having an azine, diazine, oxazine or thiazine nucleus as described in JP-A-4,662,395, JP-A-4,710,570 and JP-A-4,778,210; Examples include, but are not limited to, benzylidene leuco dye compounds as described in U.S. Pat. No. 4,923,792. Another class useful in the present invention is those derived from azomethine leuco dyes or indoaniline leuco dyes. The dyes herein are often referred to herein because many of the dyes are useful in advanced wet development photography. It is prepared by oxidative coupling with a nitrenediamine compound or a p-aminophenol compound. Reduction of the corresponding dye as described, for example, in U.S. Pat. No. 4,374,921 forms a chromogenic leuco dye. Chromogenic leuco dyes are also described in U.S. Pat. No. 4,594,307. Cyanogenic leuco dyes having short-chain carbamoyl protectors are described in EP-A-533,008. For a review of chromogenic leuco dyes, see K. Ventkataraman, The Chemistry of Synthetic Dyes, Academic Press, New York. 1952, Vol. 4, Chapter VI. Another class useful in the present invention are "aldazine" and "ketazine" dyes. Dyes of this type are described in U.S. Pat. Nos. 4,587,211 and 4,795,697. Benzylidene leuco dyes are also useful in the present invention. Dyes of this kind are described in U.S. Pat. No. 4,923,792. Another class of dye-releasing materials that form diffusible dyes upon oxidation are known as pre-formed-dye-release (PDR) or redox-dye-release (RDR) compounds. It is. In these compounds, the reducing agent for the organic silver compound releases a mobile preformed dye upon oxidation. Examples of these materials are disclosed in U.S. Pat. No. 4,981,775 (Swain). Further, as another image forming material, the mobility of a compound having a dye moiety as described in Japanese Patent Application Publication No. 165,054 (1984) is important for the oxidation / reduction reaction with silver halide. The resulting changing substances, or organic silver salts, can also be used at elevated temperatures. Also, the reducing agent can be a compound that releases a conventional photographic dye coupler or developer upon oxidation, as is known in the art. The dyes formed or released in the various colored forming layers should of course be different. Preferably there is at least a 60 nm difference in the reflection maximum absorption. In particular, there is at least a 80-100 nm difference in the maximum absorption of the dye formed or released. If three dyes are to be formed, two of them must preferably have at least this minimum difference, the third dye preferably having at least one of the other dyes, There must be a difference of at least 150 nm, especially at least 200 nm. Reducing agents that can be oxidized with silver ions to form or release visible dyes are useful in the present invention, as described above. The total amount of any leuco dye used as a reducing agent useful in the present invention is preferably in the range from 0.5 to 25% by weight, in particular from 1 to 10% by weight, based on the total weight of the individual layers using the reducing agent. It must be in the range of weight percent. Binder The photosensitive silver halide, non-photosensitive source of reducible silver, reducing agent and other additives used in the present invention are generally added to at least one binder. The binders that can be used in the present invention can be used independently or in combination with one another. Preferably, the binder is selected from polymeric materials (eg, natural and synthetic resins) that are sufficiently polar to maintain other components in the solution or suspension. Typical hydrophilic binders are transparent or translucent hydrophilic colloids. Examples of hydrophilic binders include proteins such as gelatin, gelatin derivatives, cellulose derivatives, etc .; polysaccharides such as starch, gum arabic, pullulan, dextrin, etc .; and synthetic polymers (eg, polyvinyl alcohol, polyvinyl pyrrolidone, acrylamide polymers) And water-soluble polyvinyl compounds). Another example of a hydrophilic binder is a latex-like dispersed vinyl compound used for the purpose of improving the dimensional stability of a photographic element. Examples of typical hydrophobic binders are polyvinyl acetal, polyvinyl chloride, polyvinyl acetate, cellulose acetate, polyolefin, polyester, polystyrene, polyacrylonitrile, polycarbonate, methacrylate copolymer, maleic anhydride copolymer, butadiene-styrene copolymer and the like. is there. Copolymers, such as terpolymers, are also included within the definition of polymer. Particularly preferred are polyvinyl acetals such as polyvinyl butyral and polyvinyl formal, and vinyl copolymers such as polyvinyl acetate and polyvinyl chloride. The binder can be hydrophilic or hydrophobic, but is preferably hydrophobic in the silver-containing layer. In some cases, the above polymers may be used in combination of two or more thereof. The binder is preferably used on a basis of about 30 to about 90%, especially about 45 to about 85% by weight of the emulsion layer. If the proportion and activity of the non-photosensitive reducing agent for the reducible silver source requires a particular development time and temperature, the binder must be resistant under those conditions. In general, it is preferred that the binder does not decompose or lose its structural integrity at 250 ° F. (121 ° C.) for 60 seconds, particularly, at 350 ° F. (177 ° C.) for 60 seconds. It is preferable not to lose integrity. The polymer binder may be used in combination of two or three. Such polymers are used in an amount sufficient to carry the components to be dispersed therein, ie, within an effective range of action as a binder. The effective range can be appropriately determined by those skilled in the art. Photothermographic Composition The composition for the photothermographic emulsion layer comprises a binder, a photosensitive silver halide, a non-photosensitive reducible silver source, a non-photosensitive reductant for a reducible silver source, and optionally added. Can be prepared by dissolving and dispersing the substance in an inert organic solvent such as, for example, toluene, 2-butanone, or tetrahydrofuran. The use of "toners" or derivatives thereof to improve the image is highly desirable but not essential to the element. The toner may be included in an amount of 0.01 to 10%, preferably 0.1 to 10% by weight of the emulsion layer. Toner is a material well known in the photothermographic art, as shown in U.S. Patent Nos. 3,080,254, 3,847,612, and 4,123,282. Examples of toners include phthalimide and N-hydroxyphthalimide; cyclic imides such as succinimide, pyrazolin-5-one and quinazolinone, 1-phenylurazole, 3-phenyl-2-pyrazolin-5-one and 2,4. -Thiazolidinedione; naphthalimides (eg, N-hydroxy-1,8-naphthalimide); cobalt complexes (eg, cobalt hexamine trifluoroacetate); mercaptans (eg, 3-mercapto-1,2,4-triazole) 2,2-dimercaptopyrimidine, 3-mercapto-4,5-diphenyl-1,2,4-triazole and 2,5-dimercapto-1,3,4-thiodiazole); N- (aminomethyl) Aryldicarboximides [eg, (N, N-dimethylaminomethyl) phthalimide, and N- (dimethylaminomethyl) na Taren-2,3-dicarboximide]; combinations of blocked pyrazoles, isothiuronium derivatives and certain photobleaches [eg N, N'-hexamethylene-bis (1-carbamoyl-3,5-dimethylpyrazole) Combination of 1,8- (3,6-diazaoctane) bis (isothiuronium) trifluoroacetate and 2- (tribromomethylsulfonylbenzothiazole)]; 3-ethyl-5-[(3-ethyl-2-benzo Merocyanine dyes such as thiazolinylidene) -1-methylethylidene] -2-thio-2,4-o-azolidinedione; phthalazinone, phthalazinone derivatives, or metal salts of these derivatives [eg, 4- (1 -Naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethoxyphthalazinone, and 2,3-dihydro-1,4-phthalazinedione]; Combinations of phthalic acid derivatives and phthalazinones (eg, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid, and tetrachlorophthalic anhydride); quinazolinedione, benzoxazine or naphthoxazine derivatives; halogens as well as tone modifiers Rhodium complexes that also function as halide ion sources for forming silver halide in situ [eg, ammonium hexachlororhodium (III) complex, rhodium bromide, rhodium nitrate, and potassium hexachlororhodium (III) complexes]; inorganic Peroxides and persulfides (eg, ammonium peroxydisulfate and hydrogen peroxide); benzoxazine-2,4-diones [eg, 1,3-benzoxazine-2,4-dione, 8-methyl -1,3-benzoxazine-2,4-dione and 6-nitro- , 3-benzoxazine-2,4-dione]; pyrimidines and asymmetric triazines (eg, 2,4-dihydroxypyrimidine, 2-hydroxy-4-aminopyrimidine and azauracil); and tetraazapentalene derivatives (eg, 3,6-dimercapto-1,4-diphenyl-1H, 4H-2,3a, 5,6a-tetraazapentalene and 1,4-di (o-chlorophenyl) -3,6-dimercapto-1H, 4H- 2,3a, 5,6a-tetraazapentalene). The photothermographic elements used in this invention can protect against the further formation of haze and can be stabilized against loss of sensitivity during storage. Although not required for the practice of the present invention, it may be advantageous to add a mercury (II) salt to the emulsion layer as an anti-fogging agent. Preferred mercury (II) salts for this purpose are mercury acetate and mercury bromide. Other suitable anti-fogging agents and stabilizers which can be used alone or in combination include the thiazolium salts described in U.S. Pat. Nos. 2,131,038 and 2,694,716; Azaindenes described in 2,886,437; triazaindolizines described in 2,444,605; mercury salts described in U.S. Pat. No. 2,728,663; U.S. Pat. Urazoles described in 3,287,135; sulfocatechols described in U.S. Pat. No. 3,235,652; oximes described in British Patent 623,448; U.S. Pat. No. 839,405; polyvalent metal salts described in U.S. Pat. No. 3,220,839; thyuronium salts described in U.S. Pat. No. 3,220,839; and U.S. Pat. Nos. 2,566,263 and 2,597,915. To Placing the palladium, salts of platinum and gold. The photothermographic elements of the present invention are, for example, polyalcohols and diols of the type described in U.S. Pat. No. 2,960,404; U.S. Pat. Nos. 2,588,765 and 3,121,060. Fatty acids or esters as described in US Pat. No. 5,095,061; and plasticizers and lubricants such as silicone resins as described in GB 955,061. The photothermographic element of this invention can include an image-forming dye stabilizer. Such image dye stabilizers are disclosed in British Patent No. 1,326,889, and in U.S. Patent Nos. 3,432,300, 3,698,909, and 3,574,627. No. 3,573,050, No. 3,764,337, and No. 4,042,394. The photothermographic element of the present invention is disclosed in U.S. Pat. Nos. 3,253,921, 2,274,782, 2,527,583, 2,956,879, Light absorbing substances, antihalation agents, acutances and filter dyes as described in US Pat. Nos. 5,266,452 and 5,314,795 can also be included. If desired, the dye can be mordanted, for example, as described in US Pat. No. 3,282,699. Further, in addition to the particles used in the present invention for optical effects, the photothermographic elements of the present invention include starch, titanium dioxide, zinc oxide, silica, and U.S. Pat. Matting agents such as polymer beads including beads of the type described in 2,701,245 may be included. Photothermographic elements include antistatic or conductive layers [e.g., layers comprising soluble salts (e.g., chlorides, nitrates, etc.), metallized layers, U.S. Pat. Nos. 2,861,056 and No. 3,206,312, or a layer comprising an insoluble inorganic salt as described in U.S. Pat. No. 3,428,451]. Photothermographic Structure The photothermographic element of the present invention can be composed of one or more layers on a support. The monolayer structure comprises silver halide, a non-photosensitive source of reducible silver, a reducing agent for a non-photosensitive reducible silver source, a binder, a toner, a dye-forming or dye-releasing substance, a coating aid and other components. It must contain any substances, such as adjuvants. The bilayer construction comprises a silver halide and a non-photosensitive source of reducible silver in one emulsion layer (usually the layer adjacent to the support) and the other in the second or both layers. , A two-layer structure consisting of a single emulsion layer coating containing all the components and a protective topcoat. Multicolor photothermographic dried silver structures may contain this set of overlays for each color, or may include all of the ingredients in a single layer, as described in U.S. Pat. No. 4,708,928. May be included. In the case of multilayer multicolor photothermographic elements, the various emulsion layers are generally provided with a functional or non-functional barrier between the various photosensitive layers, as described in U.S. Pat. No. 4,460,681. By using layers, they are kept separate from each other. A barrier layer, preferably comprising a polymeric material, may also be included in the photothermographic element of the present invention. The polymer for the barrier material can be selected from natural and synthetic polymers (eg, gelatin, polyvinyl alcohol, polyacrylic acid, sulfonated polystyrene, etc.). The polymer can optionally be blended with a barrier aid such as silica. Alternatively, the composition can be spray-dried or encapsulated to produce solid particles, which can then be redispersed in another (preferably different) binder and then coated on a support. The composition for the emulsion layer may also include a coating aid such as a fluoroaliphatic polyester. The photothermographic emulsion used in the present invention can be prepared by wire rod coating, dip coating, air knife coating, curtain coating, or extrusion die coating using a hopper of the type described in U.S. Pat. No. 2,681,294. It can be coated by various coating procedures, including: If desired, two or more layers can be coated simultaneously by the procedures described in U.S. Pat. No. 2,761,791 and British Patent No. 837,095. A typical wet thickness of the emulsion layer can be about 10-150 μm, and the layer can be dried in forced air at a temperature of about 20-100 ° C. When measured with a MacBeth color densitometer TD504 using a color filter that is a complementary color of the color of the dye, the maximum image density in the range of 0.2 or more, more preferably in the range of 0.5 to 4.0 is obtained. It is preferred to select the thickness of the layer to obtain. Further, if it is desired to separate the imaging chemistry of the different emulsion layers, as disclosed in US Pat. No. 5,264,321, a separate emulsion layer is coated on both sides of the transparent substrate. It may be desirable. Development conditions will vary depending on the structure used, but will typically involve heating the imagewise exposed article to a suitable elevated temperature. When used in photothermographic elements, the latent image obtained after exposing the heat-sensitive structure may be at a moderately elevated temperature (e.g., about 80-250C, preferably about 100-200C) for a sufficient amount of time (generally, (From about 1 second to about 2 minutes) and can be developed by heating the material. The heating may be performed by a typical heating means (for example, a hot plate, an iron, a hot roller, a heat generator using carbon or white titanium, and the like). In one method, development is performed in two steps. Thermal development occurs at the higher temperature (eg, about 150 ° C. for about 10 seconds), followed by thermal diffusion at the lower temperature (eg, about 80 ° C.) in the presence of a conversion solvent. A second heating step at the lower temperature causes the already formed dye to diffuse from the emulsion layer to the receiving layer without further development. Support The photothermographic emulsion used in the present invention can be coated on a wide variety of supports. The support (also known as the substrate) can be selected from a wide range of materials, depending on the imaging requirements. The support may be transparent or at least translucent. Typical supports include polyester films, primed polyester films (eg, polyethylene terephthalate or polyethylene naphthalate films), cellulose acetate films, cellulose ester films, polyvinyl acetal films, polyolefin films (eg, polyethylene or polypropylene or a mixture thereof). Blends), polycarbonate films, and related or resinous materials, as well as glass, paper, and the like. Typically, a flexible support, especially a polymer film support, is used and can be partially acetylated or coated, especially with a polymer primer or primer. Preferred polymeric materials for the support include polymers having excellent thermal stability (eg, polyesters). Particularly preferred polyesters are polyethylene terephthalate and polyethylene naphthalate. Substrates having a heat-resistant layer on the back can also be used in photothermographic imaging systems, as shown in U.S. Pat. No. 4,374,921. Use as a Photomask As mentioned above, the low absorbance potential of the photothermographic element at 380 nm in the non-imaged areas is attributed to the subsequent exposure of the UV-sensitive imaging medium to the photothermographic element of the present invention. Promote use. For example, imaging and subsequent development of a photothermographic element provides a visible image. The developed photothermographic element absorbs ultraviolet radiation in areas where there is a visible image and transmits ultraviolet radiation where there is no visible image. Thereafter, the developed element can be used as a mask and positioned between a source of ultraviolet energy and an ultraviolet-sensitive imaging medium, such as, for example, a photosensitive polymer. This step is particularly useful when the imaging medium comprises a printing plate and the photothermographic element is supplied as an imaging film. Appropriate modifications and variations can be made from the above description without departing from the spirit and scope of the invention as defined in the appended claims. The objects and advantages of the present invention will be illustrated by the following examples, which are not intended to limit the present invention unduly, as are the specific materials and amounts thereof, as well as other conditions and details, defined in the following examples. Should be considered. EXAMPLES All of the materials used in the following examples are readily available from standard commercial sources, such as Aldrich Chemical Co., Milwaukee, Wis., Unless otherwise specified. did. The following additional terms and materials were used. Acryloid® A-21 is an acrylic copolymer from Rohm and Haas, (Rohm and Haas, Philadelphia, PA). Butvar B-79 is a polyvinyl butyral from Monsanto Company (St. Louis, MO). CAB 171-15S is a cellulose acetate butyrate manufactured by Eastman Kodak Company. Desmodur® N3300 is an aliphatic triisocyanate from Mobay Chemicals, Pittsburgh, PA. Gelva® V1.5 is a polyvinyl acetate resin from Monsanto Company (St. Louis, Mo.). MEK is methyl ethyl ketone (2-butanone). MR-60 is a polyketone resin manufactured by Mohawk. Permanax® WSO is 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -3,5,5-trimethylhexane [CAS RN = 7292-14-0] Manufactured by Vulnax International Ltd. It is also known as Nonox. PE-2200 is a shell-made polyester resin. PET is polyethylene terephthalate. Dye-1 has the structure shown below. Its preparation is disclosed in pending US patent application Ser. No. 08 / 202,941 (filed Feb. 28, 1994). Dye-2 has the structure shown below. Its preparation is disclosed in EP-A-0616014. 2- (Tribromomethylsulfonyl) quinoline has the following structure. The fluorinated terpolymer A has the following random polymer structure (where m = 7, n = 2 and p = 1). The preparation of fluorinated terpolymer A is described in pending U.S. patent application Ser. No. 08 / 104,888, filed Aug. 10, 1993. Examples 1-4 As described above, the adhesion of a coated emulsion layer of a photothermographic element to a support can be measured by adding an "adhesion promoting resin" or metallic soap to the silver-containing emulsion layer coating layer composition (i.e., the support). To the first layer adjacent to the first layer). An "adhesion promoting resin" is a resin that meets the following two criteria: When coated on a flat polyester from a solvent, the resin adheres more strongly to the support than polyvinyl butyral (if polyvinyl butyral is the primary binder in the silver halide containing layer); When coated onto a flat polyester from a solvent as a blend with polyvinyl butyral (if polyvinyl butyral is the primary binder in the silver halide containing layer), the resin blend adheres more strongly to the substrate than polyvinyl butyral . In order to confirm a resin that satisfies the criterion 1 for polyvinyl butyral, more than 100 resins out of 25 resins were solvent-coated on polyester, and the adhesiveness of the resulting film was compared with that of polyvinyl butyral. The types of resins evaluated were acrylic, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, ethyl cellulose, cellulose nitrate, hydroxypropyl cellulose, polyamide, polycaprolactone, polyester, polyketone, polystyrene, and polystyrene copolymer (styrene-acrylonitrile, Styrene-maleic anhydride, styrene-butadiene), polyvinyl toluene, polyurethane, polyvinyl acetal, polyvinyl butyral, polyvinyl acetate, polyvinyl chloride copolymer and terpolymer, polyvinyl pyrrolidone, polyvinyl pyrrolidone / vinyl acetate copolymer, chlorinated rubber, phenoxy resin , Polyimide and epoxy resin. Resins from the following types have shown superior adhesion to polyesters compared to polyvinyl butyral: acrylic, cellulose acetate butyrate, polyamide, polyanhydride, polyester, polyketone, polystyrene copolymer, vinyl toluene copolymer, poly Vinyl acetate, polyvinylpyrrolidone / vinyl acetate copolymer, chlorinated rubber and polyimide. To identify resins that meet Criterion 2, a solution of polyvinyl butyral is mixed with a solution of each resin that meets Criterion 1, the resin blend is coated on polyester, and the resulting film is adhered to polyvinyl butyral. It was compared with the adhesiveness. Resins meeting this criterion include cellulose acetate butyrate [CAB551-0.2, manufactured by Eastman Chemicals], polyester [Vitel PE-22000, PE-2700 (manufactured by Shell)], polyketone [K-3886, K-1717B, MR-60 (Mohawk), Union Carbide 252], Styrene-butadiene [Goodyear Pliolite S5A], Vinyl-toluene -Butadiene (Priolite VT from Goodyear), polyvinyl acetate (AYAC from Union Carbide, Gerva (R) V1.5 from Monsanto) and polyvinylpyrrolidone / vinyl acetate (PVP / VA E-335, GAF). Granular metallic soaps evaluated to enhance the adhesion of the silver layer to the polyester were magnesium stearate and zinc stearate. Example 1 The following example shows the adhesion of the resin to the polyester (criterion 1). Butvar® B-79 polyvinyl butyral resin (manufactured by Monsanto), Vittel PE-220 polyester resin (manufactured by Shell), Gerva® V1.5 polyvinyl acetate resin (manufactured by Monsanto), MR-60 polyketone resin (manufactured by Monsanto) Mohawk), Acryloid B-66 acrylic resin (Rohm and Haas) and Styron 685D polystyrene resin (Dow) were prepared by dissolving the resin in a suitable solvent. A comparison of each solution is summarized in the second column of Table 1. Each solution was coated at 2.5 miL (0.06 mm) wet thickness onto a 7 miL (0.18 mm) polyester film and dried at 77-82 ° C (170-180 ° F) for 3 minutes. The adhesion of the resin layer to the support layer for each sample was determined using Method B of ASTM D3359-92a, a 2 mm cross-cut tester (manufactured by Byk-Gardner) and a 3M # 610 tape [manufactured by 3M (Cent. Paul, Minn.)] Using the standard test method for measuring adhesion by tape test. This test evaluates the adhesion of the coating to the support and classifies the adhesion on a scale of 0 to 5 (0 is the poorest adhesion and 5 is the best adhesion). . The results, shown in Table 1 below, show that certain resins adhere more strongly to the polyester support than polyvinyl butyral. Example 2 The following example shows the adhesion of Resin / Butvar B-79 to polyester (criterion 2). A resin meeting criteria 1 from Table 1 was blended with Butvar B-79 by mixing the Butuval B-79 solution listed in Table 1 with a 20% resin in methyl ethyl ketone. The proportions of each resin solution are listed in Table 2 below. The resulting solution was coated on 7 miL (0.18 mm) polyester at a wet thickness of 2.5 miL and dried at 170-180 ° F for 3 minutes. The adhesiveness of the resin layer to the support for each sample was determined in the same manner as in Example 1. In this case, the adhesion classification of each sample based on the ASTM D 3359-92a test method was 0 even though there was a clear difference in adhesion between the various samples. Therefore, an adhesion classification was used in which the amount of film peel resistance was subjectively compared to the amount of the control Butvar B-79. Table 2 shows the results. Example 3 The following example illustrates the use of an adhesion promoting resin for a photothermographic silver emulsion layer. Resins meeting the above criteria 1 and 2 improve the adhesion of the photothermographic silver emulsion layer to a polyester support, as shown in the examples below. Preparation of Preformed Core-Shell Type Silver Bromide Iodide Emulsion A pre-formed core-shell silver bromoiodide emulsion was prepared by the method described in U.S. Patent Application Serial No. 08 / 199,114, filed February 22, 1994, the contents of which are incorporated herein. The preformed silver soap contained 2.0% by weight of a core-shell silver bromoiodide emulsion of 0.05 μm in diameter (25% core containing 8% iodide; and all bromide shell 75). %). Homogenization of preformed soap (homogenate): A homogenate of a preformed fatty acid silver salt was prepared by homogenizing the following components. Methyl ethyl ketone 76.0 g Toluene 1.0 g Butvar B-79 2.2 g Preformed core-shell type silver salt dispersion 20.8 g The above components were mixed at 21 ° C. for 10 minutes and kept for 24 hours. The mixture was homogenized at 4000 psi and then again at 8000 psi. Silver emulsion coating solution for photothermography: Homogenate 513.1 g Pyridinium hydrobromide perbromide 2.48 g (15 wt% in methanol) Calcium bromide 3.79 g (15 wt% in methanol) 2-mercapto-5-methylbenzimidazole 0.35 g 2- (3-chloro Benzolyl) benzoic acid 3.91 g Dye-1 0.073 g Methanol 16.07 g Butvar B-79 124.01 g 2- (tribromomethylsulfonyl) quinoline 37.89 g (8% by weight in MEK) Permanax WSO 29.15 g Desmodur N3300 diisocyanate 2.35 g (66.7% by weight in MEK) Tetrachlorophthalic acid 3.70 g (26% by weight in MEK) 13.13 g of phthalazine (22% by weight in MEK) The first two listed above The two components were mixed at 21 ° C. for 60 minutes. After adding calcium bromide and stirring the mixture for another 30 minutes, imidazole, benzoic acid, dye and methanol were added. After mixing for 30 minutes, the dispersion was cooled to 10 ° C. Next, butvar and 2- (tribromomethylsulfonyl) quinoline were added and the dispersion was mixed for 30 minutes. The remaining components were each added separately with a mixing interval of 15 minutes. The following four samples (3A, 3B, 3C and 3D) were prepared by adding 40.0 g of the photothermographic silver emulsion coating solution to the corresponding resin. Topcoat solution: The following components were mixed in order to prepare a topcoat solution. Methanol 10.68 g Methyl ethyl ketone (MEK) 81.07 g Tetrachlorophthalic anhydride 0.06 g CAB 171-15S (cellulose acetate butyrate) 7.14 g Fluorinated terpolymer A (16% by weight in MEK) 0.50 g Acryloid A -21 (acrylic copolymer) 0.27 g 4-methylphthalic acid 0.27 g Each of Examples 3A to D was dual-coated on a 7 miL (0.18 mm) polyester with a topcoat solution (during a single trip, in tandem). Or continuous coating). The silver emulsion orifice for photothermography is set at 3.7 to 4.0 miL (0.09 to 0.10 mm), and the top coat solution orifice is 5.2 to 5.5 miL (0.13 to 0.14 mm). Set to. The coating was dried at 82 ° C (180 ° F) for 3 minutes. The sample was exposed with an infrared laser sensitometer containing an 811 nm semiconductor laser and developed at 124 ° C. (255 ° F.) for 15 seconds. Sensitivity wedges were scanned and analyzed on a computer densitometer. The initial sensitivity data is shown in Table 3 below. ASTM D3359-92a Method B, "Standard Test for Measuring Adhesion by Tape Test, Using 2mm Cross Cut Tester (Byk-Gardner) and 3M # 601 Tape (3M Corporation, St. Paul, Minn.) Method, the adhesion of the resin layer to the support in the Dmax image area for each sample was determined. The results are shown in Table 4 below. Example 4 The following example illustrates the improvement in adhesion using zinc stearate. Homogenization of preformed soap (homogenate): A homogenate of a preformed fatty acid silver salt was prepared by homogenizing the following components. 79.5 g of methyl ethyl ketone 1.0 g of toluene 1.9 g of Butvar B-79 17.6 g of a preformed core-shell type silver salt dispersion 17.6 g The above components were mixed at 21 ° C. for 10 minutes and kept for 24 hours. The mixture was homogenized at 4000 psi and then again at 8000 psi. Silver emulsion coating solution for photothermography: Homogenate 70.85 g pyridinium hydrobromide perbromide 0.44 g (18 wt% in methanol) calcium bromide 0.43 g (15 wt% in methanol) butvar B-79 15.46 g 2- (tribromomethylsulfonyl) quinoline 4. 25 g [Anti-fogging agent A (8% by weight in MEK)] Permanax 2.93 g Desmodur N3300 triisocyanate 0.30 g (66.7% by weight in MEK) Tetrachlorophthalic acid 0.47 g (26% by weight in MEK) 2-mercapto-5-methylbenzimidazole 0.05 g 2- (3-chlorobenzolyl) benzoic acid 0.55 g Dye-2 0.001 g methanol 2.72 g Phthalazine 1.53 g (24% by weight in MEK) The first two components listed were mixed at 10 ° C. for 120 minutes. After adding calcium bromide and stirring the mixture for a further 30 minutes, Butvar B-79 and antifoggant A were added. Permanax, Desmodur N3300 triisocyanate and tetrachlorophthalic acid were added separately with a mixing interval of 15 minutes. After mixing for 30 minutes, the dispersion was kept at 10 ° C. for 16 hours. 2- (3-chlorobenzolyl) benzoic acid, dye-2 and methanol. This emulsion coating dispersion was used in Example 4a. A dispersion of methyl ethyl ketone (71.74 parts), toluene (10.76 parts), butvar B-791.68 parts and zinc stearate (15.82 parts) was homogenized to prepare a zinc stearate dispersion. 50.0 g of the silver emulsion coating dispersion from above was combined with 5.27 g of zinc stearate dispersion to prepare a silver emulsion coating dispersion for photothermography. This emulsion coating dispersion was used in Example 4b. Topcoat solution: The following components were mixed in order to prepare a topcoat solution. Methanol 10.69 g Methyl ethyl ketone (MEK) 80.88 g Tetrachlorophthalic anhydride 0.13 g CAB 171-15S (cellulose acetate butyrate) 7.06 g Fluorinated terpolymer A (16% by weight in MEK) 0.49 g Acryloid A -21 (acrylic copolymer) 0.27 g 4-methylphthalic acid 0.30 g Super-P Flex 200 (calcium carbide, 0.17 g from Specialty Minerals, Inc.) Emulsion coating dispersion, Example 4a (control) and top The coating solution was dual coated on 7 miL (0.18 mm) polyester at a wet thickness of 4.2 miL (0.11 mm) and 5.6 miL (0.14 mm), respectively, and at 180 ° F. for 3 minutes. Dried. The emulsion coating dispersions, Example 4a (invention), Example 4b, and the topcoat solution were wetted onto 7 miL (0.18 mm) polyester with a wet thickness of 4.6 miL (0.12 mm) and 6.0 miL (0.1 mm). 15 mm) and dried at 82 ° C. (180 ° F.) for 3 minutes. Each coated film was exposed with an infrared laser sensitometer containing an 811 nm semiconductor laser and developed by heating to 124 ° C. (255 ° F.) for 15 seconds. Silver layer to support in Dmax area for each sample according to ASTM D3359-92a test method using a 2 mm cross cut tester (Byk-Gardner) and 3M # 601 tape (3M Corporation, St. Paul, Minn.). Was determined. Appropriate modifications and variations can be made from the above description without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (1)

[Claims]   1. Polyvinyl acetal binder, non-photosensitive silver source, silver ion reducing agent And light on at least one surface comprising radiation-sensitive silver halide grains. Spectral sensitized photothermographic silver halide element including a support having a thermographic layer Wherein the layer containing both silver halide and a non-photosensitive silver source is a) Polymers with better adhesion to polyesters than Rivinyl Acetal and b) Includes an adhesion promoter selected from the group consisting of fine metal soaps other than silver soap Element consisting of.   2. The silver halide grains have a number average grain size of at least 80% of the entire grains. Preformed silver halide grains having an average of ± 0.05 μm with a size of less than 10 μm. Item 10. The element according to item 1.   3. The photothermographic emulsion layer comprises particles of the polymer and a metal of the carboxylic acid. Including particles having a number average size of 0.5 to 12 μm selected from the group consisting of soap particles. The element of claim 1 comprising:   4. The number average size of the silver halide grains is between 0.01 and 0.08 µm. An element according to 1, 2, or 3.   5. The element of claim 1 wherein metallic soap particles are included in said layer.   6. The polymer particles comprise halo in an amount of 0.5 to 20% by weight of polyvinyl acetal. 4. The method of claim 3 wherein said layer comprising silver genide and a silver source is included. Elementary.   7. 7. The method according to claim 1, wherein the support layer comprises polyester. Element.   8. Claims 1, 2, 3, wherein the polyvinyl acetal is polyvinyl butyral. An element according to 5 or 6.   9. Cellulose acetate butyrate, polyester, styrene-butadiene, vinyl Toluene-butadiene, polyvinyl acetate and polyvinyl pyrrolidone / bi acetate 2. A polymer particle comprising a resin selected from the group consisting of nil. , An element according to 2, 3, 5 or 6.   10. A metal soap other than silver soap and a carboxylic acid soap 2. The element of claim 1 comprising:   11. The polymer is treated with light in an amount of 0.5 to 40% by weight of the polyvinyl acetal. The element of claim 1 which dissolves in the thermographic layer.   12. The resin is polyvinyl ketone and polyvinyl pyrrolidone / vinyl acetate; 12. The element of claim 11, wherein the element is selected from the group consisting of: