Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/494—Silver salt compositions other than silver halide emulsions; Photothermographic systems ; Thermographic systems using noble metal compounds
  • G03C1/498—Photothermographic systems, e.g. dry silver
  • G03C1/49872—Aspects relating to non-photosensitive layers, e.g. intermediate protective layers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
  • Y10S430/162—Protective or antiabrasion layer

Definitions

• ABSTRACT Certain acrylamide polymers in a layer contiguous to a photothermographic layer comprising (a) photographic silver halide in association with (b) a silver salt of certain heterocyclic thione compounds, (c) an organic reducing agent, and (d) a polymeric, synthetic binder for the photothermographic layer of a photothermographic element provide, for example, increased stability prior to imagewise exposure without significantly adversely affecting sensitometric properties of the photothermographic element.
• the acrylamide polymers can comprise an overcoat layer or a layer between the photothermographic layer and a support for the photothermographic element or can be in both such layers.
• This invention relates to certain acrylamide polymers in certain photothermographic materials comprising photographic silver halide in association with a silver salt of certain heterocyclic thione compounds.
• a photothermographic element comprising a support having thereon (I) a layer comprising the described silver salts of a heterocyclic thione and a contiguous layer (II) comprising certain acrylamide copolymers.
• a method of developing a latent image in a photothermographic element comprising the described acrylamide polymers In another of its aspects, it relates to a method of developing a latent image in a photothermographic element comprising the described acrylamide polymers.
• Phototherrnographic materials comprising photographic silver halide in association with a silver salt of certain heterocyclic thione compounds and an organic reducing agent are known in the art. These photothermographic materials are described, for example, in US. Pat. No. 3,785,830 issued Jan. I5, I974.
• One problem which has been encountered with these photothermographic materials is the need for increased preprocessing stability of the photothermographic element. This problem is illustrated in the following comparative Example 2. This problem is illustrated by failure of the photothermographic material to provide a desired developed image after storage at elevated temperatures such as storage at 38 C. at 50% relative hu midity.
• a commonly employed overcoat layer for photothermographic ele ments comprises cellulose acetate.
• Such an overcoat layer is described, for example, in Belgian Pat. No. 729,043 and US. Pat. No. 2,732,304 issued Jan. 24, I956.
• Such an overcoat comprising cellulose acetate does not provide a useful solution to problems encountered with photothermographic materials comprising photographic silver halide in association with silver salts of certain heterocyclic thiones as described in US. Pat. No. 3,785,830 issued Jan. 15, I974.
• Polymer overcoat layers have been proposed for photothermographic elements to reduce susceptibility to abrasion marks, especially in machine processing wherein the photothermographic layer side of the element is contacted with a metal roller or the like.
• the processing of photothermographic elements by contacting the photothermographic element with a heating means can cause undesired physical properties such as surface cracking, reticulation and bubbling which can detract from the overall image quality desired in the photothermographic element.
• An ethyl cellulose overcoat layer and other overcoat layers have not satisfactorily overcome these problems in a photothermographic element as described.
• Polymers in order to be satisfactory with the photothermographic materials as described, must satisfy each of the following characteristics in addition to those described: (1) they provide sufficient resistance to abrasion and fingerprint marking to enable machine processing, (2) they provide sufficient resistance to reticulation and surface cracking upon processing with heat in a photothermographic element, (3) they provide sufficient resistance to surface bubbling in a photothermographic material upon processing with heat, (4) they do not significantly adversely afiect sen sitometric properties of the photothermographic materials, and (5) they are sufficiently transparent for desired viewing of an image.
• a photothermographic element comprising a support having thereon a layer comprising (a) photographic silver halide in association with (b) a silver salt of a heterocyclic thione as described herein, (c) an organic reducing agent for the silver salt of the heterocyclic thione, and (d) a polymeric, synthetic binder for layer (I) and a polymer layer (II), contiguous to layer (I), wherein the polymer layer (II) comprises at least 50% by weight of a polymer (A) comprising the repeating units represented by the formulas:
• R is hydrogen or alkyl containing l to 4 carbon atoms
• azonia nitrogen-containing ring such as an imidazoliurn salt group, such as a l-aza- 3-methyl-3-azoniacyclopenta-2,4-diene-l-yl methosulfate salt group, or a pyridinium salt group, such as l,2-dimethyl-l-azonia-S-phenyl methosulfate salt group, and
• the weight ratio of starting monomers for the units B and C is, respectively, about 60:40 to 100:0.
• the described polymers are acrylamide polymers.
• the acrylamide polymers are preferably copolymers which exhibit reduced or no adverse physical or chemical properties resulting from the thermal processing described herein. This is intended to mean that the described polymers are preferably copolymers which do not adversely discolor, decompose, crystallize, flow or the like as a result of the heating described herein.
• a process for developing an image in the described photo thermographic element by uniformly heating the element, such as from about 80 to about 200 C., for a sufficient time to provide the desired developed image.
• This process can be carried out by contacting the photothermographic element with a suitable heating means to provide the described temperature.
• Useful acrylamide polymers do not adversely flow, smear or distort at the processing temperatures for a described photothermographic material.
• the acrylamide polymers also do not cause adverse opacification of the photothermographic material.
• Useful acrylamide polymers have an average molecular weight of at least about 50,000, and preferably from about 100,000 to about 2,000,000. The molecular weight can be determined by methods known in the polymer art.
• Useful acrylamide polymers have inherent viscosities, measured at a concentration of 0.25 g. per deciliter in 1 normal sodium chloride solution at 25 C., ranging from 0.2 to 2.0, and preferably from 0.6 to 17.
• Useful acrylamide polymers are typically transparent and colorless. It is necessary, if the polymer is not completely transparent, that it be at least transparent to the wavelength of radiation employed to provide a latent image in the photothermographic element of the invention when exposure is through a layer comprising the acrylamide polymer.
• acrylamide polymers especially acrylamide copolymers, useful in photothermographic elements according to the invention are described in, for example, U.S. Pat. No. 3,658,878 of Smith issued Apr. 25, 1972.
• U.S. Pat. No. 3,591,386 of Abbott et al. issued July 6, 1971 U.S. Pat. No. 3,488,708 of Smith issued Jan, 6, 1970, U.S. Pat. No. 3,459,790 of Smith issued Aug. 5, 1969, and U.S. Pat. No. 3,554,987 of of Smith issued Jan. 12, 1971.
• Useful acrylamide polymers can be prepared empolying procedures known in the polymer art, such as described in the above U.S. patents. Generally, any of the known poly merization procedures, particularly copolymerization procedures used in the polymer art, are useful for making the described acrylamide polymers.
• Typical reactants employed when preparing the polymers within the described structure (A) are acrylamide and acrylamide copolymerized with one of the following monomers:
• Examples of useful acrylamide polymers according to the invention include:
• the concentration of acrylamide polymer which is useful in a layer of a photothermographic element according to this invention can vary, depending upon such factors as the particular photothermographic ele ment, processing conditions, components in the photothermographic element, particular acrylamide polymer and the like.
• a useful concentration range or coating coverage is about 0.1 g. to about 1.08 g. of acrylamide polymer/m. of support of the photothermographic element.
• a useful concentration of acrylamide polymer, when the acrylamide polymer is used as an overcoat layer is about 0.3 g. to about 7.5 g., such as about 0.40 g. to about 2.15 g., of acrylamide polymer/m. of support of the photothermographic element.
• a useful concentration of acrylamide polymer is about 0.3 g. to about 5.0 g., such as about 2.15 g. of acrylamide polymer/m. of support of the photothermographic element.
• the described acrylamide polymer comprises at least 50% by weight of the layer contiguous the photothermographic layer (1) as described.
• Other polymers can be useful with the acrylamide copolymers. However, typically, the acrylamide polymer comprises about 100% of the contiguous layer.
• Other polymers which can be useful with the acrylamide polymers include, for example, poly(vinyl alcohol) and polymers having properties similar to poly(vinyl alcohol) such as other acrylamide and N-substituted acrylamide copolymers including. for instance, poly-(acrylamide-co-acrylic acid), and cellulosic materials such as sulfoethyl cellulose and sodium cellulose sulfate.
• Photothermographic elements according to this invention can comprise, if desired, multiple polymer-containing layers.
• the photothermographic element can comprise an overcoat layer containing an acrylamide polymer as described and an additional overcoat layer comprising another polymer such as poly(vinyl alcohol).
• One embodiment of the invention is in a photother mographic element comprising a support having thereon (l):
• R represents the atoms completing a 5- member heterocyclic nucleus and Z is alkylene containing l to 30 carbon atoms, typically 1 to carbon atoms,
• polymer layer (ll) contiguous to (I), at least one polymer layer (ll), the improvement being one wherein said polymer layer (ll) comprises at least 50% by weight of a polymer (A) comprising the repeating units represented by the formulas:
• R is hydrogen or alkyl containing l to 4 carbon atoms, R is as described, and the weight ratio of starting monomers for the units B and C are respectively about 60:40 to l00:0.
• concentration of photographic silver halide which is useful in a photothermographic element of the invention can be very low compared with photographic materials which contain photographic silver halide in the absence of the other components of the photothermographic element of the invention.
• concentration of photographic silver halide which is suitable in a photothermographic element of the inven tion can be about 0.0025 to about 0.3 mole of photographic silver halide per mole of silver as the silver salt of the described heterocyclic thione.
• the concentration of photographic silver halide is typically about 0. l0 times 10' to about 1.29 times 10' moles of photographic silver halide/m of support.
• Useful photographic silver halides include, for example, silver chloride, silver bromide, silver iodide, silver bromoiodide, silver chloro bromoiodide, silver iodide, or mixtures thereof.
• the photographic silver halide can be coarseor fine-grain, very fine-grain silver halide being especially useful.
• the photographic silver halide can be prepared by any of the known procedures employed in the photographic art.
• the silver halide can be prepared, for example, employing single-jet preparation techniques or double-jet preparation techniques such as techniques employed in preparing Lippmann emulsions and the like.
• Surfaceimage silver halide can be useful. If desired, mixtures of surfaceand internal-image silver halide can be used. Negative-type silver halide is typically employed.
• the silver halide can be regulargrain silver halide such as described in Klein and Moisar, Journal of Photographic Science, Vol. 12, No. 5, Sept-Oct, l964. pp. 242-251. Photographic silver iodide is especially useful as the photographic silver halide.
• the photographic silver halide according to this invention can be unwashed or washed, and can be chemically sensitized employing techniques empolyed in the photographic art.
• the latent image formed in the photographic silver halide upon imagewise exposure of the photothermographic material increases the reaction rate between the components of the photothermographic material upon heating of the photothermo graphic material. It is believed this enables a lower processing temperature to be employed for developing an image which otherwise would not be possible.
• photographic silver halide in association with is intended to mean the photographic silver halide is in a location with respect to the other described components of the photothermographic material which enables this desired lower processing temperature and provides a more useful developed image.
• a useful silver salt of a heterocyclic thione is a silver salt of a heterocyclic thione represented by the formula (XX) as described. Selection of an optimum heterocyclic thione silver salt will depend upon such factors as the particular photothermographic material, particular toning agent, processing temperature, desired image and the like.
• Examples of useful 5- member heterocyclic nuclei containing the described carboxyalkyl group are thiazoline-Z-thione, benzothiazoline-Z-thione, imida2oline-2-thione, oxazoline-Z- thione, or similar heterocyclic thione nuclei.
• the heter ocyclic thione nucleus can be substituted with groups which do not adversely affect the photothermographic properties of the photothermographic element of the invention, such as alkyl containing l to 3 carbon atoms, or phenyl.
• thiazoline-Z-thiones represented by the formula:
• Z is alkylene containing 1 to 4 carbon atoms; and R and R are each, independently, hydrogen, alkyl containing l to 4 carbon atoms, such as methyl, ethyl, propyl or butyl, or aryl containing 6 to 10 carbon atoms, such as phenyl or tolyl, or taken together are the atoms necessary to complete a benzo group represented by the broken line between R and R
• Other useful heterocyclic thiones within formula (XX) are imidazoline-Z-thiones represented by the formula:
• Z is alkylene containing 1 to 4 carbon atoms
• R and R are each, independently, hydrogen, alkyl containing 1 to 4 carbon atoms, such as methyl, ethyl, propyl or butyl, or aryl containing 6 to 10 carbon atoms, such as phenyl or tolyl, or taken together are the atoms necessary to complete a benzo group represented by the broken line between R and R"; and R is alkyl, typically alkyl containing 1 to 3 carbon atoms, such as methyl, ethyl or propyl, aryl containing 6 to carbon atoms, such as phenyl, or carboxyalkyl such as carboxyalkyl containin l to 3 carbon atoms, for example, carboxymethyl and carboxyethyl.
• Other useful heterocyclic thiones within structure (XX) are oxazoline- 2-thiones represented by the formula:
• alkylene includes straight-chain alkylene and branched-chain alkylene, such as:
• Preparation of the thione compounds can be carried out employing procedures described, for example, in an article of R. W. Lamon and W. J. Humphlett, Journal of Heleroc'yclic Chemistry, Vol. 4, pp. 605609, 1967, or as described in Belgian Pat. No. 739,705.
• Preparation of 4-thiazoline-2-thiones bearing a carboxyalkyl group in the 3 position can, for instance, be effected by treating a dithiocarbamic acid derived from an amino acid and carbon disulfide with an a-halogenated ketone. In this process the use of methyl alcohol as a solvent can improve the solubility of the reactants.
• the preparation of the silver salt of 3-carboxymethyl- 4-methyl-4-thiazoline-2-thione is typical.
• This silver complex is prepared by mixing the described thiazoline-2-thione with silver trifluoroacetate in water and thoroughly dispersing the reactants. Concentrations of the reactants can be varied to provide the desired ratio of silver to heterocyclic compound. Typically, the ratio of the thione compound to silver ion is less than about 2: l
• the resulting silver salt can be purified and stored for later mixture with other components of the described photothermographic materials. Dispersing of the silver trifluoroacetate with the heterocyclic compound is typically carried out at about 38 to about 71 Various reducing agents can be employed in the photothermographic materials of the invention.
• polyhydroxybenzenes such as hydroquinones including, for instance, hydroquinone; alkyl-substituted hydroquinones such as tertiarybutylhydroquinone, methylhydroquinone, 2,5-dimethylhy droquinone and 2,6
• silver halide developing agents which can be employed as reducing agents include reductones such as anhydro dihydro piperidino hexose reductone; hydroxytetronic acids and hydroxytetronimides; 3-pyrazolidones such as l-phenyl- 3-pyrazolidone 4-methyl-4- hydroxymethyl l -phenyl-3-pyrazolidone, and those described in British Pat. No. 930,572 published July 3, 1963; hydroxylamines; ascorbic acids such as ascorbic acid, ascorbic acid ketals, and other ascorbic acid derivatives; phenylenediamines; aminophenols; and the like. Combinations of reducing agents can also be employed.
• a suitable reducing agent typically is one which in the photothermographic compositions of the invention provides a developed image within about sec. at a temperature of about l00 to 250 C.
• a photothermographic element according to the invention can comprise a support having thereon in the photothermographic layer (A) about 0.10 times l0 to about 1.29 times l0 moles of photographic silver halide in association with (B) about 2.69 times ID to about 21.5 times 10 moles of reducing agent and (C) about 2.69 times 10 to about 2l .5 times 10 moles of silver as the described complex per m of support.
• A about 0.10 times l0 to about 1.29 times l0 moles of photographic silver halide in association with
• B about 2.69 times ID to about 21.5 times 10 moles of reducing agent and
• C about 2.69 times 10 to about 2l .5 times 10 moles of silver as the described complex per m of support.
• An optimum concentration of each component will depend upon such factors as the particular components, the desired image, processing temperature and the like.
• one or more components of the photothermographic element can be present in one or more lay ers of the element.
• the reducing agent, silver salt of the described heterocyclic thione and/or photographic silver halide in the described layer (ll) comprising an acrylamide polymer. This can reduce, for example, migration of certain addenda throughout the layers of the photothermographic element.
• Suitable binders for photothermographic layer (1) can be hydrophilic or hydrophobic, transparent or translucent, and include synthetic polymeric materials useful in the described photothermographic materials. It is desirable in many cases to use an acrylamide polymer both as a component of polymer layer (11) and as a binder for layer (1). Useful acrylamide polymers for this purpose are within the described formulae.
• Typical supports include those film supports which can withstand processing temperatu res employed for developing an image in a photothermographic element of the invention.
• film supports include, for example, cellulose ester film, poly(vinyl acetal) film, polystyrene film, poly(ethylene terephthaL ate) film, polycarbonate film, film supports as described in U.S. Pat. No. 3,634,089 of Hamb issued Jan. ll, 1972, and U.S. Pat. No. 3,725,070 of Hamb et al. issued Apr. 3, 1973, and related films or resinous materials.
• Other useful supports include glass, paper, metal and the like. Typically, a flexible support is employed.
• the photothermographic elements according to the invention can contain addenda commonly employed in photothermographic elements, such as antistatic and- /or conducting layers, plasticizers, lubricants, surfactants, matting agents, sensitizing dyes, brightening agents, light-absorbing materials, filter dyes, antihalation dyes, absorbing dyes and the like.
• addenda commonly employed in photothermographic elements such as antistatic and- /or conducting layers, plasticizers, lubricants, surfactants, matting agents, sensitizing dyes, brightening agents, light-absorbing materials, filter dyes, antihalation dyes, absorbing dyes and the like.
• a toning agent can be employed in the photothermographic element of the invention to provide a desired image.
• useful toning agents include, for example, certain heterocyclic compounds which can provide a more neutral tone image.
• useful toning agents include 3-mercapto-1,2,4-triazole and 2,4dimercaptopyrimidine, described in copending U.S. application Ser. No. 466,331, of White, filed May 2, 1974.
• the various components of the photothermographic materials of the invention can be added from water solutions, or suitable organic solvents can be useful to aid in addition.
• the components can be mixed using various procedures known in the photographic art.
• a hardener especially an aldehyde hardener like formaldehyde
• This can provide improved incubation stability.
• a range of concentration of the aldehyde hardener can be employed depending upon such factors as the particular acrylamide polymer, particular components of the photothermographic element, desired image, desired stability and the like.
• a concentration of about 0.l to about such as about 0.1 to about 5%, by weight of aldehyde hardener, particularly formaldehyde, is incorporated in the acrylamide polymer before coating on the photothermographic element.
• the aldehyde hardener in the acrylamide polymer when the acrylamide polymer is coated directly on the support before coating of the photothermographic layer.
• the aldehyde hardener can be employed in any one or more of the layers of the photothermographic element.
• improved incubation stability is observed when the photothermographic element containing the aldehyde hardener is stored for a period of time, such as about at least 2 days, before imagewise exposure and processing as described. It is believed that this storage time permits a crosslinking of the polymer in the photothermographic element. However, the exact mechanism which results in the improved incubation stability is not fully understood.
• An especially useful embodiment of the invention comprises a photothermographic element comprising a support having thereon, respectively, (A) a layer comprising about 1.08 g./m. of support of poly(acrylamide-co-l-vinylimidazole) (weight ratio :10) containing 1% by weight of formaldehyde, (B) a photothermographic layer containing photographic silver iodide in association with a silver salt of a heterocyclic thione as described, a hydroquinone reducing agent for the silver salt of the heterocyclic thione, and a synthetic polymeric binder comprising poly(acrylamide-co-Z- acetoacetoxyethyl mmethacrylate) (weight ratio 98:2) or poly(acrylamide-co-l-vinylimidazole) (weight ratio 90:10), and (C) an overcoat layer comprising about L08 g./m. of support of poly(acrylamide-co-lvinylimidazole (weight ratio 90:10).
• a range of concentration of the described acrylamide polymer can be useful in an overcoat on the described photothermographic element according to the invention. While such factors as the particular photothermographic materials, the particular acrylamide copolymer, processing temperature and the like will influence the optimum concentration range of acrylamide copolymer in the overcoat layer, typically a concentration of about 0.3 to about 7.5 g., such as about 0.4 to about 2.l5 g., of acrylamide copolymer in the overcoat layer per m. of support is useful.
• a useful reducing agent concentration range in the acrylamide copolymer when the acrylamide copolymer is used as an overcoat is typically about 0.25 to about 0.55 g. of reducing agent per m. of support.
• concentration of about 2.15 to about 4.30 g. of reducing agent is used per m? of support.
• Photothermographic materials according to the invention are typically sensitive to the ultraviolet and blue regions of the spectrum and exposure means which provide this radiation are preferred.
• a photothermographic element according to the invention is exposed imagewise with a visible light source such as a tungsten lamp.
• a visible image can be developed in a photothermographic element as described, after imagewise exposure, within a short time by overall heating of the photothermographic element.
• the photothermographic element can be overall heated for about 1 to about 90 sec. at a temperature of about 100 to about 200 C., preferably about l40 to about l70 C.
• the time of heating is less than about 20 sec., such as about l to about 4 sec., at a temperature of about l5O to about 170 C.
• Increasing or decreasing the length of time of heating can enable use of a lower or higher temperature within the described range.
• the heating means can be, for example, a simple hot plate, iron or roller; or hot-air convection heating means; or dielectric heating means.
• the described acrylamide polymers can be useful in various layers of photothermographic materials known in the art, such as materials described in U.S. Pat. No. 3,589,903 of Birkeland issued June 29, l97l, U.S. Pat. No. Reissue 26,719 of Sorenson et al. issued Nov. 18, 1969, U.S. Pat. No. 3,429.706 of Shepard et al. issued Feb. 25, I969, U.S. Pat. No. 3,645,739 of Ohkubo et al. issued Feb. 29, 1972, U.S. Pat. No. 3,515,559 of Druker et al. issued June 2, l970, and U.S. Pat. No.
• the described acrylamide polymers can be useful in thermographic materials also.
• Thermographic materials in which the acrylamide polymers can be useful are described, for example, in U.S. Pat. Nos. 2,910,377 and 3,094,417 ofworkman issued June l8, 1963. Selection of an optimum acrylamide polymer as described for use in one or more layers of the photothermographic materials or thermographic materials described in the above art will depend upon such factors as the compatability of the acrylamide polymer with the other components of the photothermographic or thermographic material, the desired image, processing temperature and the like.
• the acrylamide polymers described are used with hydrophilic materials such as photothermographic materials coated from aqueous formulations.
• EXAMPLE l poly(vinyl alcohol) as a binder 2.15 gJm. hydroquinone l.
• the resulting layer was designated layer (1).
• poly(vinyl alcohol) as a binder surfactant (Surfactant 106 which is a nonylphenoxypolyglycidol sold by Rohm and Haas Co., USA.
• Poly(acrylamide-co-2-acetoacetoxyethyl methacrylate) (weight ratio 98:2) (inherent viscosity l.40) measured in L0 N NaCl solution at a concentration of 0.25 g./dl. at a temperature of 25 C. was then coated on layer (2) at the concentration of 7.26 g. of the acrylamide copolymer per m? of support.
• the acrylamide copolymer layer was designated layer (3).
• the resulting photothermographic element was packaged in a so-called double paper envelope, that is, a black paper envelope inside a yellow paper envelope.
• the double paper envelope was stored in a controlled temperature-relative humidity chamber at 38 C. and 50% relative humidity.
• samples of the photothermographic element were removed from the double paper envelope and imagewiseexposed for 10 sec. to xenon light in a sensitometer.
• the samples of exposed photothermographic element were uniformly heated after exposure by passing them over a metal roller for 4 sec. at C. A developed image was observed in each of the samples.
• the Dmax, Dmin and photographic speed for each of the images in the samples were the same as those of an image developed in an equivalent photothermographic element with the exception that the imagewise exposure and image development were carried out without storing the photothermographic element for a period of time.
• EXAMPLE 2 This is a comparative example.
• a control photothermographic element (B) was prepared as in Example 1 without the described acrylamide copolymer overcoat (layer 3), and then imagewiseexposed and developed in the same manner as in Example 1. This control photothermographic element provided no acceptable developed image after storage for 14 days under the described incubation conditions in a double paper envelope.
• the resulting layer was designated as layer (2).
• the resulting photothermographic element was imagewise-exposed to tungsten light as described in Examples 4-10 and then overall heated by contacting the element with a metal block at 160 CV for 4 see. A de veloped image is observed.
• the image had the sensitometric properties given in following Table 2.
• EXAMPLE 12 The procedure in Example 1 l was repeated with the exception that an overcoat containing 1.08 g./m. of poly(acrylamide-co-2-acetoacetoxyethyl methacrylate) (weight ratio 98:2) was applied to layer (2) prior to imagewise exposure.
• the resulting sensitometric properties are reported in following Table 2.
• the overcoated photothermographic element was T bl 2 imagewise-exposed to tungsten light in a sensitometer l b L E R l for sec.
• the exposed photothermographic element gg was overall heated by contacting it with a metal block
• Similar samples of the photothermographic element were incubated in a double paper H f h 1'3 rcfuence poi, envelope at 38 C and 50% relative humidity for up to i )2 3 WEE S 15 days.
• the resulting samples were then lm agewlse- 12 fresh 08 reference pom exposed and overall heated as above.
• the Dmin. Dmax 25 1 week 108 .06 and relative photographic speed values for each photo- 2 098 3weeks 1.16 .14 thermographic element are given in following Table 1.
• a resin-coated paper support was coated with 1.08 g./m. of polymer Vll containing 1% by weight of formaldehyde based on the weight of the polymer. This was designated as layer (1 On layer 1) was coated a photothermographic composition containing:
• 3-mercapto-l .2.4 triazole 0.022 g./rn. isopropylhydroquinone 1.62 g./m.
• Surfactant 100 0.008 g./m. total silver as silver iodide and 0.81 g./m.
• a resin-coated paper support was coated with a layer comprising a mixture of the following:
• the sensitometric results of the photothermographic element are given in following Table 3, including the results from incubation.
• silver iodide gelatino emulsion 0.075 g. Ag/m. silver complex of 3-carboxy 0.68 g. Ag/m? methy1-4-methyl-4-thiazo1ine Z-thione tertiary-hutylhydroquinorie 1.88 g./m. 3-mcrcapto1.2,4triazo1e 0.0094 gjm. 2.4-dimercuptopyrimidine 0.0024 g./m. Surfactant 106 0.008 g./m.
• R represents atoms completing a 5 member heterocyclic nucleus and Z is alkylene containing 1 to 30 carbon atoms,
• an organic reducing agent for said silver salt of a heterocyclic thione and d. a polymeric, synthetic binder and contiguous to (l), at least one polymer layer (H), the improvement wherein said polymer layer (II) comprises at least 50% by weight of a polymer (A) compris ing the repeating units represented by the formulas:
• R is hydrogen or alkyl containing 1 to 4 carbon atoms
• R is an imidazolyl, N-substituted carbamoyl, 2-
• pyrrolidonyl acetoacetoxyethoxycarbonyl, acetoacetonylmethylphenyl, ethoxycarbonylaceto, pyridyl, hydroxy, hydroxyalkyl containing 1 to 4 carbon atoms, carboxy, carboxyethoxycarbonyl, a heterocyclic ammonium salt group having a S- or 6-membered azonia nitrogen-containing ring, or a pyridinium salt group, and
• the weight ratio of starting monomers for said units B and C is, respectively. about 60:40 to lz0.
• a photothermographic element as in claim 1 also comprising in said layer (II) at least one polymer other than said copolymer (A),
• a photothermographic element as in claim 1 comprising a support having thereon, in sequence:
• a photothermographic layer comprising:
• a photothermographic element as in claim 1 wherein said polymeric synthetic binder comprises a polymer selected from the group consisting of poly(acrylamide), poly(acrylamide-co-Z-acetoacetoxyethyl methacrylate), poly(acrylamide-co-a-chloroacrylic acid), poly(acrylamide-co-l-vinylimidazole), poly- (vinyl alcohol), and combinations thereof.
• a photothermographic element as in claim 1 also comprising a hardener in said layer ([1).
• a photothermographic element as in claim 1 also comprising a aldehyde hardener in said layer (ll).
• a photothermographic element as in claim 1 also comprising a 3-mercapto-l,2,4-triazole toner.
• a photothermographic element as in claim 1 also comprising a 2,4-dimercaptopyrimidine toner.
• a process of developing a latent image in a photothermographic element as defined in claim 1 comprising heating said element to a temperature of about to about 200 C.

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• Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)

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Cited By (19)

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Citations (6)

• 1974
  • 1974-07-16 US US489029A patent/US3893860A/en not_active Expired - Lifetime
  • 1974-09-10 CA CA208,883A patent/CA1027409A/fr not_active Expired
• 1975
  • 1975-07-15 FR FR7522062A patent/FR2279131A1/fr active Granted
  • 1975-07-15 DE DE19752531563 patent/DE2531563A1/de active Pending
  • 1975-07-16 JP JP50086257A patent/JPS5135320A/ja active Pending
  • 1975-07-16 GB GB29848/75A patent/GB1510539A/en not_active Expired
  • 1975-07-16 BE BE158365A patent/BE831443A/fr unknown

Patent Citations (6)

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