Source: https://patents.justia.com/patent/20080057450
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US Patent Application for Thermally developable materials containing reducing agent combinations Patent Application (Application #20080057450 issued March 6, 2008) - Justia Patents Search
Justia Patents And Inorganic Silver CompoundUS Patent Application for Thermally developable materials containing reducing agent combinations Patent Application (Application #20080057450)
Incorporating a combination of phenolic reducing agents provides thermally developable materials with improved silver efficiency and hot-dark print stability without loss in other sensitometric properties. Both photothermographic and thermographic materials are provided, and particularly photothermographic materials having lower silver coverage.
This invention relates to thermally developable materials having a mixture of phenolic reducing agents to provide improved silver efficiency and hot-dark print stability. This invention also relates to methods of imaging and using these materials.
In photothermographic materials, all of the “chemistry” for imaging is incorporated within the material itself. For example, such materials include a reducing agent (that is, a developer for the reducible silver ions) while conventional photographic materials usually do not. The incorporation of the reducing agent into photothermographic materials can lead to increased formation of various types of “fog” or other undesirable sensitometric side effects.
These and other distinctions between photothermographic and photographic materials are described in Unconventional Imaging Processe, E. Brinckman et al. (Eds.), The Focal Press, London and New York, 1978, pp. 74-75, in D. H. Klosterboer, Imaging Processes and Materials, (Neblette's Eighth Edition), J. Sturge, V. Walworth, and A. Shepp, Eds., Van Nostrand-Reinhold, New York, 1989, Chapter 9, pp. 279-291, in C. Zou et al., J. Imaging Sci. Technol. 1996, 40, pp. 94-103, and in M. R. V. Sahyun, J. Imaging Sci. Technol. 1998, 42, 23.
One problem encountered in the use of thermally developable materials is inadequate covering power by the developed silver image. This can be caused by incomplete development of the non-photosensitive silver salt, by the morphology of the developed silver, or by a combination of these two factors. Increased covering power results in higher image density for the same amount of thermally developable silver salt and allows lower silver coating weights to be utilized. Because silver salts are expensive, increased covering power can lower manufacturing costs. A convenient measure of covering power is “silver efficiency”, the maximum density (Dmax) of an imaged and processed thermally developable material divided by the silver coating weight.
U.S. Pat. Nos. 6,413,712 (Yoshioka et al.) and U.S. Pat. No. 6,645,714 (Oya et al.) describe various binary mixtures of bisphenols with monophenols or trisphenols with monophenols as reducing agents (developers) in photothermographic materials.
Despite the considerable research and knowledge in the art relating to various reducing agents in thermally developable materials, there remains a need for additional effective reducing agent combinations that provide more efficient use of silver and allow a reduction in the amount of silver needed to reach a given density.
b. a combination of reducing agents for the reducible silver ions, and
c. a polymeric binder,
wherein the combination of reducing agents comprises at least one trisphenol represented by the following Structure (I), and
(a) at least one monophenol represented by the following Structure (II) or at least one bisphenol represented by the following Structure (III), or
(b) at least one monophenol represented by the following Structure (II) and at least one bisphenol represented by the following Structure (III):
wherein L1, L2, and L3 are independently sulfur or a mono-substituted or unsubstituted methylene group,
R1 and R2 are independently primary or secondary substituted or unsubstituted alkyl groups having I to 12 carbon atoms,
R3, R4, R5, R19, and R20 are independently substituted or unsubstituted alkyl groups having 1 to 12 carbon atoms, substituted or unsubstituted alkoxy groups having 1 to 12 carbon atoms, or halo groups,
R6, R7, R8, R9, R10, R11, R21, R22, R23 and R24 are independently hydrogen or any substituent that is substitutable on a benzene ring,
R12 and R13 are independently substituted or unsubstituted alkyl exclusive of 2-hydroxyphenylmethyl groups, substituted or unsubstituted alkoxy, or halo groups, or hydrogen, such that both R12 and R13 are not both simultaneously hydrogen,
R14, R15, and R16 are independently hydrogen, or any substituent that is substitutable on a benzene ring,
R17 and R18 are independently substituted or unsubstituted alkyl groups, and
n is an integer of 1 or greater, provided that when n is 2 or greater, L4 is a single bond or a linking group that is attached to any of R12, R13, R14, R15 or R16.
c. a combination of reducing agents for the reducible silver ions, and
wherein said combination of reducing agents comprises at least one trisphenol represented by the Structure (I) identified above, and
(a) at least one monophenol represented by Structure (II) identified above or at least one bisphenol represented by Structure (III) identified above, or
(b) at least one monophenol represented by Structure (II) identified above and at least one bisphenol represented by Structure (III) identified above.
In preferred embodiments, the invention includes a black-and-white, organic solvent based photothermographic material comprising a support and having on at least one side thereof a photothermographic layer and comprising, in reactive association:
wherein the total amount of silver is present in an amount of at least 1 g/m2 and less than or equal to 2.5 g/m2,
the combination of reducing agents includes the combination of either or both of Compounds I-2 and I-3 with either or both of Compounds II-8 and II-17,
the combination of either or both of Compounds I-2 and I-3 with either or both of Compounds III- 1 and III-4, or
the combination of either or both of Compounds I-2 and I-3 with either or both of Compounds II-8 and II-17 and either or both of Compounds III-1 and III-4,
a co-developer compound that is optionally present in an amount of from about 0.0005 to about 0.15 g/m2, and
a high contrast enhancing agent that is optionally present in an amount of from about 0.001 to about 0.5 g/m2.
(B) simultaneously or sequentially, heating the exposed photothermo-graphic material to develop the latent image into a visible image.
We have found that by incorporating specific combinations of a mixture of trisphenol with monophenol and/or bisphenol reducing agents in the thermally developable materials, we have improved Silver Efficiency with little change in other sensitometric properties. In fact, initial Dmin and print stability in the dark during storage under hot conditions (known as “hot-dark print stability”) are improved. Additionally, improvements in Image Tone may also be obtained. These advantages are particularly evident when the coating level of silver is reduced from those normally used in photothermographic materials.
The thermally developable materials described herein are both thermographic and photothermographic materials. While the following discussion will often be directed primarily to the preferred photothermographic embodiments, it would be readily understood by one skilled in the art that thermo-graphic materials can be similarly constructed and used to provide black-and-white or color images using appropriate imaging chemistry and particularly non-photosensitive organic silver salts, reducing agents, toners, binders, and other components known to a skilled artisan. In both thermographic and photothermo-graphic materials, the reducing agent combinations described herein are in reactive association with the non-photosensitive silver salt.
The thermally developable materials described herein can be used in black-and-white or color thermography or photothermography and in electronically generated black-and-white or color hardcopy recording. They can be used in microfilm applications, in radiographic imaging (for example digital medical imaging), X-ray radiography, and in industrial radiography. Furthermore, the absorbance of these materials between 350 and 450 nm is desirably low (less than 0.5), to permit their use in the graphic arts area (for example, image-setting and phototype-setting), in the manufacture of printing plates, in contact printing, in duplicating (“duping”), and in proofing.
For some embodiments, it may be useful that the photothermo-graphic materials be “double-sided” or “duplitized” and have the same or different photothermographic coatings (or imaging layers) on both sides of the support. In such constructions each side can also include one or more protective overcoat layers, primer layers, interlayers, acutance layers, conductive/antistatic layers auxiliary layers, anti-crossover layers, and other layers readily apparent to one skilled in the art, as well as the required conductive layer(s).
In the descriptions of the photothermographic materials, “a” or “an” component refers to “at least one” of that component (for example, the combination of reducing agent compounds described herein).
The term “hot-dark print stability” refers to the susceptibility of imaged and processed (photo)thermographic materials to undergo changes in such properties as Dmin, Dmax, tint, and tone during storage under hot conditions in the absence of light.
As noted above, photothermographic materials include one or more photocatalysts in the photothermographic emulsion layer(s). Useful photo-catalysts are typically photosensitive silver halides such as silver bromide, silver iodide, silver chloride, silver bromoiodide, silver chlorobromoiodide, silver chlorobromide, and others readily apparent to one skilled in the art. Mixtures of silver halides can also be used in any suitable proportion. Silver bromide and silver iodide are preferred. More preferred is silver bromoiodide in which any suitable amount of iodide is present up to almost 100% silver iodide and more likely up to about 40 mol % silver iodide. Even more preferably, the silver bromoiodide comprises at least 70 mole % (preferably at least 85 mole % and more preferably at least 90 mole %) bromide (based on total silver halide). The remainder of the halide is iodide, chloride, or chloride and iodide. Preferably the additional halide is iodide. Silver bromide and silver bromoiodide are most preferred, with the latter silver halide generally having up to 10 mole % silver iodide.
The silver halide grains may have a uniform ratio of halide throughout. They may also have a graded halide content, with a continuously varying ratio of, for example, silver bromide and silver iodide or they may be of the core-shell type, having a discrete core of one or more silver halides, and a discrete shell of one or more different silver halides. Core-shell silver halide grains useful in photothermographic materials and methods of preparing these materials are described in U.S. Pat. No. 5,382,504 (Shor et al.). Iridium and/or copper doped core-shell and non-core-shell grains are described in U.S. Pat. No. 5,434,043 (Zou et al.) and U.S. Pat. No. 5,939,249 (Zou). Bismuth(III)-doped high silver iodide emulsions for aqueous-based photothermographic materials are described in U.S. Pat. No. 6,942,960 (Maskasky et al.).
In some constructions, it is preferable to form the non-photo-sensitive source of reducible silver ions in the presence of ex-situ-prepared silver halide. In this process, the source of reducible silver ions, such as a long chain fatty acid silver carboxylate (commonly referred to as a silver “soap” or homogenate), is formed in the presence of the preformed silver halide grains. Co-precipitation of the source of reducible silver ions in the presence of silver halide provides a more intimate mixture of the two materials to provide a material often referred to as a “preformed soap” [see U.S. Pat. No. 3,839,049 (Simbns)].
The silver halide grains used in the imaging formulations can vary in average diameter of up to several micrometers (aim) depending on the desired use. Preferred silver halide grains for use in preformed emulsions containing silver carboxylates are cubic grains having a number average particle size of from about 0.01 to about 1.0 μm, more preferred are those having a number average particle size of from about 0.03 to about 0.1 μm. It is even more preferred that the grains have a number average particle size of 0.06 μm or less, and most preferred that they have a number average particle size of from about 0.03 to about 0.06 μm. Mixtures of grains of various average particle size can also be used. Preferred silver halide grains for high-speed photothermographic constructions use are tabular grains having an average thickness of at least 0.02 μm and up to and including 0.10 μm, an equivalent circular diameter of at least 0.5 μm and up to and including 8 μm and an aspect ratio of at least 5:1. More preferred are those having an average thickness of at least 0.03 μm and up to and including 0.08 μm, an equivalent circular diameter of at least 0.75 μm and up to and including 6 μm and an aspect ratio of at least 10:1.
The photosensitive silver halides can be chemically sensitized using any useful compound that contains sulfur, tellurium, or selenium, or may comprise a compound containing gold, platinum, palladium, ruthenium, rhodium, iridium, or combinations thereof, a reducing agent such as a tin halide or a combination of any of these. The details of these materials are provided for example, in T. H. James, The Theory of the Photographic Process, Fourth Edition, Eastman Kodak Company, Rochester, N.Y., 1977, Chapter 5, pp. 149-169. Suitable conventional chemical sensitization procedures are also described in U.S. Pat. No. 1,623,499 (Sheppard et al.), U.S. Pat. No. 2,399,083 (Waller et al.), U.S. Pat. No. 3,297,446 (Dunn), U.S. Pat. No. 3,297,447 (McVeigh), U.S. Pat. No. 5,049,485 (Deaton), U.S. Pat. No. 5,252,455 (Deaton), 5,391,727 (Deaton), U.S. Pat. No. 5,759,761 (Lushington et al.), and U.S. Pat. No. 5,912,111 (Lok et al.), and EP 0 915 371A1 (Lok et al.).
In addition, sulfur-containing compounds can be decomposed on silver halide grains in an oxidizing environment according to the teaching in U.S. Pat. No. 5,891,615 (Winslow et al.). Examples of sulfur-containing compounds that can be used in this fashion include sulfur-containing spectral sensitizing dyes. Other useful sulfur-containing chemical sensitizing compounds that can be decomposed in an oxidizing environment are the diphenylphosphine sulfide compounds described in U.S. Pat. No. 7,026,105 (Simpson et al.) and U.S. Pat. No. 7,063,941 (Burleva et al.), and in U.S. Patent Application Publication 2005/0123871 (Burleva et al.).
The chemical sensitizers can be present in conventional amounts that generally depend upon the average size of the silver halide grains. Generally, the total amount is at least 10−1 mole per mole of total silver, and preferably from about 10−8 to about 10−2 mole per mole of total silver for silver halide grains having an average size of from about 0.01 to about 1 μm.
Suitable spectral sensitizing dyes such as those described in U.S. Pat. No. 3,719,495 (Lea), U.S. Pat. No. 4,396,712 (Kinoshita et al.), U.S. Pat. No. 4,439,520 (Kofron et al.), U.S. Pat. No. 4,690,883 (Kubodera et al.), U.S. Pat. No. 4,840,882 (Iwagaki et al.), U.S. Pat. No. 5,064,753 (Kohno et al.), U.S. Pat. No. 5,281,515 (Delprato et al.), U.S. Pat. No. 5,393,654 (Burrows et al.), U.S. Pat. No. 5,441,866 (Miller et al.), U.S. Pat. No. 5,508,162 (Dankosh), U.S. Pat. No. 5,510,236 (Dankosh), and 5,541,054 (Miller et al.), Japan Kokai 2000-063690 (Tanaka et al.), 2000-112054 (Fukusaka et al.), 2000-273329 (Tanaka et al.), 2001-005145 (Arai), 2001-064527 (Oshiyama et al.), and 2001-154305 (Kita et al.) can be used. Useful spectral sensitizing dyes are also described in Research Disclosure, December 1989, item 308119, Section IV and Research Disclosure, 1994, item 36544, section V.
Teachings relating to specific combinations of spectral sensitizing dyes also include U.S. Pat. No. 4,581,329 (Sugimoto et al.), U.S. Pat. No. 4,582,786 (Ikeda et al.), U.S. Pat. No. 4,609,621 (Sugimoto et al.), U.S. Pat. No. 4,675,279 (Shuto et al.), 4,678,741 (Yamada et al.), U.S. Pat. No. 4,720,451 (Shuto et al.), U.S. Pat. No. 4,818,675 (Miyasaka et al.), 4,945,036 (Arai et al.), and U.S. Pat. No.4,952,491 (Nishikawa et al.).
An appropriate amount of spectral sensitizing dye added is generally about 10−10 to 10−1 mole, and preferably, about 10-7 to 10-2 mole per mole of silver halide.
Silver salts other than the silver carboxylates described above can be used also. Such silver salts include silver salts of aliphatic carboxylic acids containing a thioether group as described in U.S. Pat. No. 3,330,663 (Weyde et al.), soluble silver carboxylates comprising hydrocarbon chains incorporating ether or thioether linkages or sterically hindered substitution in the α-(on a hydrocarbon group) or ortho-(on an phenyl group) position as described in U.S. Pat. No. 5,491,059 (Whitcomb), silver salts of dicarboxylic acids, silver salts of sulfonates as described in U.S. Pat. No. 4,504,575 (Lee), silver salts of sulfosuccinates as described in EP 0 227 141A1 (Leenders et al.), silver salts of aryl carboxylic acids (such as silver benzoate), silver salts of acetylenes as described, for example in U.S. Pat. No. 4,761,361 (Ozaki et al.) and U.S. Pat. No. 4,775,613 (Hirai et al.), and silver salts of heterocyclic compounds containing mercapto or thione groups and derivatives as described in U.S. Pat. No. 4,123,274 (Knight et al.) and U.S. Pat. No. 3,785,830 (Sullivan et al.).
Sources of non-photosensitive reducible silver ions can also be core-shell silver salts as described in U.S. Pat. No. 6,355,408 (Whitcomb et al.), wherein a core has one or more silver salts and a shell has one or more different silver salts, as long as one of the silver salts is a silver carboxylate. Other useful sources of non-photosensitive reducible silver ions are the silver dimer compounds that comprise two different silver salts as described in U.S. Pat. No. 6,472,131 (Whitcomb). Still other useful sources of non-photosensitive reducible silver ions are the silver core-shell compounds comprising a primary core comprising one or more photosensitive silver halides, or one or more non-photo-sensitive inorganic metal salts or non-silver containing organic salts, and a shell at least partially covering the primary core, wherein the shell comprises one or more non-photosensitive silver salts, each of which silver salts comprises a organic silver coordinating ligand. Such compounds are described in U.S. Pat. No. 6,803,177 (Bokhonov et al.).
Organic silver salts that are particularly useful in aqueous based thermographic and photothermographic materials include silver salts of compounds containing an imino group. Preferred examples of these compounds include, but are not limited to, silver salts of benzotriazole and substituted derivatives thereof (for example, silver methylbenzotriazole and silver 5-chloro-benzotriazole), silver salts of 1,2,4-triazoles or 1 -H-tetrazoles such as phenyl-mercaptotetrazole as described in U.S. Pat. No. 4,220,709 (deMauriac), and silver salts of imidazoles and imidazole derivatives as described in U.S. Pat. No. 4,260,677 (Winslow et al.). Particularly useful silver salts of this type are the silver salts of benzotriazole and substituted derivatives thereof. A silver salt of a benzotriazole is particularly preferred in aqueous-based thermographic and photo-thermographic formulations.
Useful nitrogen-containing organic silver salts and methods of preparing them are described in U.S. Pat. No. 6,977,139 (Hasberg et al.). Such silver salts (particularly the silver benzotriazoles) are rod-like in shape and have an average aspect ratio of at least 3:1 and a width index for particle diameter of 1.25 or less. Silver salt particle length is generally less than 1 μm. Also useful are the silver salt-toner co-precipitated nano-crystals comprising a silver salt of a nitrogen-containing heterocyclic compound containing an imino group, and a silver salt comprising a silver salt of a mercaptotriazole. Such co-precipitated salts are described in U.S Pat. No. 7,008,748 (Hasberg et al.).
The total amount of silver (from all silver sources) in the thermo-graphic and photothermographic materials is generally at least 0.002 mol/m2, preferably from about 0.01 to about 0.05 mol/m2, and more preferably from about 0.01 to about 0.02 mol/m2. In other aspects, it is desirable to use total silver [from both silver halide (when present) and reducible silver salts] at a coating weight of less than 2.5 g/m2, preferably at least I but less than 2.0 g/m2, and more preferably equal to or less than 1.9 g/m2 especially in photothermographic materials.
Reducing Agent Combination
The reducing agent combination for the source of reducible silver ions comprises at least one trisphenol represented by the following Structure (I), and
wherein L1, L2, and L3 are independently sulfur or a mono-substituted or unsubstituted methylene group, R1 and R2 are independently primary or secondary substituted or unsubstituted alkyl groups having 1 to 12 carbon atoms that can be linear, branched or cyclic (such as methyl, ethyl, n-propyl, iso-propyl, iso-butyl, cyclohexyl, benzyl, 4-methylcyclohexyl, norbomyl, or isobomyl),
R3, R4, R5, R19, and R20 are independently substituted or unsubstituted alkyl groups having 1 to 12 carbon atoms (such as methyl, ethyl, n-propyl, iso-propyl, iso-butyl, tert-butyl, cyclohexyl, benzyl, 4-methyl-cyclohexyl, norbomyl, or isobomyl), substituted or unsubstituted alkoxy groups having 1 to 12 carbon atoms (such as methoxy, ethoxy, propoxy, iso-propoxy, or n-butoxy), or halo groups (such as chloro or bromo),
R6, R7, R8, R9, R10, R11, R21, R22, R23, and R24 are independently hydrogen or any substituent that is substitutable on a benzene ring,
R12 and R13 are independently substituted or unsubstituted alkyl groups having 1 to 12 carbon atoms exclusive of 2-hydroxyphenylmethyl group, (such as methyl, ethyl, n-propyl, iso-propyl, iso-butyl, tert-butyl, 1-methylcyclohexyl, cyclohexyl, benzyl, tert-pentyl, norbomyl, or isobomyl), substituted or unsubstituted alkoxy groups having 1 to 12 carbon atoms (as defined above), halo groups (such as chloro or bromo), or hydrogen, such that both R12 and R13 are not both simultaneously hydrogen,
R17 and R18 are independently substituted or unsubstituted alkyl groups having 1 to 12 carbon atoms (as defined above for R12 and R13),
n is an integer of 1 or greater, and
when n is 2 or greater, L4 is a single bond or a linking group that is attached to any of R12, R13, R14, R15, or R16.
Preferably, L1, L2, and L3 are independently methylene groups or mono-substituted methylene groups (for example, a mono-substituted methylene group substituted with one alkyl group, aryl group, cycloalkyl group, or heterocyclic group),
R1 and R2 are independently substituted or unsubstituted primary or secondary alkyl groups having 1 to 8 carbon atoms,
R3, R4, R5, R9, and R20 are independently substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms,
R6, R7, R8, R9, R10, R11, R15, R16, R21, R22, R23, and R24are independently hydrogen, or substituted or unsubstituted methyl, ethyl, or methoxy groups, or chloro groups,
R12, R13, R17, and R18 are independently substituted or unsubstituted primary, secondary, or tertiary alkyl groups having 1 to 7 carbon atoms, and
R14 is a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, and
n is 1 to 4, provided that when n is 2 or greater, L4 is a single bond or a linking group that is attached to any of R14, R15, R16.
More preferably, L1, L2, and L3 are unsubstituted methylene groups,
R1 and R2 are the same substituted or unsubstituted primary or secondary alkyl groups having 1 to 6 carbon atoms,
R3, R4, R5, R19, and R20 are the same substituted or unsubstituted methyl or ethyl groups,
R6 ,R7, R8, R9, R10, R11, R15, R16, R21, R22, R23, and R24 are independently hydrogen or unsubstituted methyl groups,
R12, R13, R17, and R18 are independently substituted or unsubstituted secondary or tertiary alkyl groups having 3 to 7 carbon atoms, and
R14is a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or in some embodiments, R14 is a group represented by —CH2CH2(C═O)— and L4 is a group represented by (—OCH2)4C-, particularly when n is 4.
One skilled in the art would understand that when n is 1, L4 is not present.
Compounds (I-1) to (I-18) in TABLE I are representative of the trisphenol reducing agents represented by Structure (I) that are useful in the present invention. Compounds (II-1) to (II-17) in TABLE II are representative of the monophenol reducing agents represented by Structure (II) that are useful in the present invention. Compounds (III-1) to (III-18) in TABLE III are representative of the bisphenol reducing agents represented by Structure (III) that are useful in the present invention. Of these listed compounds, Compounds I-2 and I-3 of TABLE I, Compounds II-8 and II-17 of TABLE II, and Compounds III-1 and III-4 of TABLE III, are preferred.
Preferred combinations of reducing agents useful in this invention include combinations of either or both of Compounds I-2 and I-3 of TABLE I with either or both of Compounds II-8 and II-17 of TABLE II. Other preferred combinations include combinations of either or both of Compounds I-2 and I-3 of TABLE I with either or both of Compounds III-1 and III-4 of TABLE III. Still other preferred combinations include combinations of either or both of Compounds I-2 and I-3 of TABLE I with either or both of Compounds II-8 and II-17 of TABLE II and either or both of Compounds III-1 and III-4 of TABLE III.
TABLE I Compound R1, R2 R3, R5 R4 L1, L2
I-1 CH3 t-C4H9 CH3 CH2 I-2 CH3 CH3 CH3 CH2 I-3 Cyclohexyl CH3 CH3 CH2 I-4 Isobornyl CH3 CH3 CH2 I-5 CH3 CH3 CH3 CH(C3H7) I-6 C2H5 CH3 CH3 CH2 I-7 CH3 C2H5 CH3 CH2 I-8 CH3 CH3 t-C4H9 CH2 I-9 CH3 CH3 C2H5 CH2 I-10 CH3 CH3 OCH3 CH2 I-11 CH3 CH3 Cl CH2 I-12 Norbornyl CH3 CH3 CH2 I-13 CH3 CH3 CH3 CH(CH2CH2C6H5) I-14 i-(C3H7) CH3 CH3 CH2 I-15 Cyclopentyl CH3 CH3 CH2 I-16 CH3 CH2CH2OH CH3 CH2 I-17 CH3 CH3 CH3 CH(CH2CH2CH2OH) I-18 CH3 CH3 Cyclohexyl CH2
TABLE II Compound R12, R13 R14 R15, R16 L4 n
II-1 t-C4H9 CH3 H Nil 1 II-2 t-C4H9 t-C4H9 H Nil 1 II-3 t-C4H9, CH3 CH3 H Nil 1 II-4 t-C4H9 COOCH3 H Nil 1 II-5 t-C4H9 COOC18H37 H Nil 1 II-6 t-C5H11 CH3 H Nil 1 II-7 t-C4H9 C9H19 H Nil 1 II-8 t-C4H9 CH2CH2(C═O)— H (—OCH2)4C 4 II-9 t-C4H9 CH2CH2(C═O)— H 2 II-10 t-C4H9 CH2— H single bond 2 II-11 t-C4H9 CH2CH2(C═O)— H —OCH2CH2O— 2 II-11 t-C4H9 CH2CH2(C═O)— H (—OCH2)3CCH2CH3 3 II-12 t-C4H9 CH2CH2O— H 3 II-13 t-C4H9 CH2CH2(C═O)— H 2 II-14 t-C4H9 CH2CH2— H single bond 2 II-15 t-C4H9 CH2— H 3 II-16 t-C4H9 CH2CH2(C═O)— H OCH2CH2—S—CH2CH2O 2 II-17 t-C4H9, CH3 CH3 CH2—, H 3
TABLE III Compound R17, R18 R19, R20 L3
III-1 t-C4H9 CH3 CH2 III-2 CH3 CH3 CH(CH2CH2C6H5) III-3 CH3 CH3 CH(Cyclohexyl) III-4 1-CH3(Cyclohexyl) CH3 CH2 III-5 Isobornyl CH3 CH2 III-6 Norbornyl CH3 CH2 III-7 CH3 CH3 CH(i-C3H7) III-8 CH3 C2H5 CH2 III-9 t-C4H9 CH3 S III-10 t-C5H11 CH3 CH2 III-11 Cyclohexyl CH3 CH2 III-12 t-C4H9 CH2CH2OH CH2 III-13 t-C4H9 CH3 CH(CH2CH2CH2OH) III-14 t-C4H9 CH3 CH(CH2CH2CH3) III-15 t-C4H9 t-C4H9 CHCH3 III-16 CH3 CH2OCH3 CH(CH2CH2CH3) III-17 CH3 CH3 CH2(C3H7) III-18 CH3 CH3 CH(CH2CH(CH3)CH2C(CH3)3)
The various phenols represented by Structures I, II, and III can be obtained from a number of commercial sources, including Aldrich Chemical Company (Milwaukee, Wis.), or they can be prepared using known synthetic methods. For example, the trisphenols represented by Structure (I) can be prepared by the procedures described in D. J. Beaver et al., J. Amer Chem. Soc., 1953, 75, 5579-81.
The mixture of phenolic reducing agents represented by the compounds of Structures I, II, and III generally provides from about 1 to about 45% (dry weight) of the emulsion layer in which it is located. In multilayer constructions, if the reducing agent(s) is added to a layer other than an emulsion layer, slightly higher proportions, of from about 2 to 55 weight % may be more desirable. Thus, the total range for the total amount of phenolic reducing agents can be from about 1 to about 55 % (dry weight). Also, these phenolic reducing agents are generally present in an amount of at least 0.05 and up to and including about 0.5 mol/mol of total silver in the thermally developable material, and preferably in an amount of from about 0.1 to about 0.4 mol/mol of total silver. Other additional reducing agents (described below) that may be present could contribute additional amounts of overall reducing agents to the imaging chemistry.
The molar ratio of the reducing agent of Structure (I) to the total reducing agents of Structure (II) or (III), or to the total reducing agents of both Structures (II) and (III), is from about 0.1:1 to about 50: 1, and preferably from about 0.1: 1 to about 10:1. The amount of the reducing agent of Structure (I) is generally from about 0.5 to about 30 % (dry weight of the layer), or from about 0.05 to about 0.5 mol/mol of total silver, and preferably is from about 1 to about 10% (dry weight) or from about 0.05 to about 0.25 mol/mol of total silver.
Additional reducing agents include the bisphenol-phosphorous compounds described in U.S. Pat. No. 6,514,684 (Suzuki et al), the bisphenol, aromatic carboxylic acid, hydrogen bonding compound mixture described in U.S. Pat. No. 6,787,298 (Yoshioka), and the compounds that can be one-electron oxidized to provide a one-electron oxidation product that releases one or more electrons as described in U.S. Patent Application Publication 2005/0214702 (Ohzeki). Other reducing agents that can be used include substituted hydrazines such as the sulfonyl hydrazides described in U.S. Pat. No. 5,464,738 (Lynch et al.). Still other useful reducing agents are described in U.S. Pat. No. 3,074,809 (Owen), U.S. Pat. No. 3,080,254 (Grant, Jr.), U.S. Pat. No. 3,094,417 (Workman), U.S. Pat. No. 3,887,417 (Klein et al.), U.S. Pat. No. 4,030,931 (Noguchi et al.), and U.S. Pat. No. 5,981,151 (Leenders et al.).
Additional reducing agents that may be used along with the reducing agent mixture described above, include amidoximes, azines, a combination of aliphatic carboxylic acid aryl hydrazides and ascorbic acid, a reductone and/or a hydrazine, piperidinohexose reductone or formyl-4-methylphenylhydrazine, hydroxamic acids, a combination of azines and sulfonamidophenols, α-cyanophenylacetic acid derivatives, reductones, indane-1,3-diones, chromans, 1,4-dihydropyridines, and 3-pyrazolidones.
Reducing agent mixtures including high contrast enhancing agents are also useful. Such materials are useful for preparing printing plates and duplicating films useful in graphic arts, or for nucleation of medical diagnostic films. These “high contrast enhancing agents” are also identified in the art as “contrast enhancing agents”, “nucleating agents”, and “silver saving agents”. Examples of such compounds are described in U.S. Pat. No. 6,150,084 (Ito et al.) and U.S. Pat. No. 6,620,582 (Hirabayashi). Certain contrast enhancing agents are preferably used in some thermographic and photothermographic materials with specific reducing agents and the co-developers described herein. Examples of such useful high contrast enhancing agents include, but are not limited to, hydroxylamines, alkanolamines and ammonium phthalamate compounds as described in U.S. Pat. No. 5,545,505 (Simpson), hydroxamic acid compounds as described for example, in U.S. Pat. No. 5,545,507 (Simpson et al.), N-acylhydrazine compounds as described in U.S. Pat. No. 5,558,983 (Simpson et al.), and hydrogen atom donor compounds as described in U.S. Pat. No. 5,637,449 (Harring et al.), all of which patents are incorporated herein by reference. It would be understood by one skilled in the art that such compounds may have varying effectiveness depending upon the imaging chemistry in which they are used and the amount at which they are used, and that they also may have multiple properties, for example, acting as co-developers as well as enhancing contrast.
The high contrast enhancing agents can be present in an amount of from about 0.0005 to about 1 g/m2 and preferably from about 0.001 to about 0.5 g/m2.
In addition to the reducing agent mixture described above, the thermally developable materials may also contain one or more co-developer compounds. “Co-developers” are organic compounds that by themselves do not act as effective reducing agents for the non-photosensitive silver salt, but when used in combination with a reducing agent and a non-photosensitive silver salt provide, upon development, increased silver development. This results in increased optical density (Dmax) and improved Silver Efficiency.
Thus, in some instances, the reducing agent composition comprises in addition to the reducing agent combination, one or more co-developers (also known as co-reducing agents). Such contrast enhancing agents can be chosen from the various classes of reducing agents described below.
Classes of co-developers that can be used in combination with the inventive co-developers described herein are trityl hydrazides and formyl phenyl hydrazides as described in U.S. Pat. No. 5,496,695 (Simpson et al.). Yet another class of co-developers includes substituted acrylonitrile compounds such as those described in U.S. Pat. No. 5,545,515 (Murray et al.) and U.S. Pat. No. 5,635,339 (Murray). Also useful are the crown ether-alkali metal complex cation of an enolate anion of an aldehyde having at least one electron withdrawing group in the alpha (α) position, as described in copending and commonly assigned U.S. Ser. No. 11/455,415 (filed Jun. 19, 2006 by Kumars Sakizadeh and Sharon M. Simpson). These patents and patent application are incorporated herein by reference.
One or more co-developer compounds can be added to any layer on the side of the support having a thermally developable thermographic or photo-thermographic emulsion layer as long as they are allowed to come into intimate contact with the emulsion layer during coating, drying, storage, thermal development, or post-processing storage. Thus one or more co-developer compounds can be added directly to the thermally developable thermographic or photothermographic emulsion layer or to one or more overcoat layers above the emulsion layer (for example a topcoat layer, interlayer, or barrier layer) and/or below the emulsion layer (such as to a primer layer, subbing layer, or carrier layer). Preferably one or more co-developer compounds are added directly to the emulsion layer or to an overcoat layer and allowed to diffuse into the emulsion layer.
Where the photothermographic material has one or more photo-thermographic layers on both sides of the support, one or more of the same or different co-developer compounds can be used on one or both sides of the support.
Generally, one or more co-developer compounds are present in a total amount of at least 0.0005 g/m2 in one or more layers on the imaging side of the support, of the emulsion layer into which they are incorporated or diffused. The co-developers are preferably present in a total amount of from about 0.0005 g/m2 to about 0.15 g/m2, and preferably present in a total amount of from about 0.001 to about 0.05 g/m2 in one or more layers on an imaging side of the support. The molar ratio of reducing agent combination to co-developer is generally from about 5,000: 1 to about 10: 1, preferably from about 1000:1 to about 100:1.
Ternary mixtures comprising the reducing agent combination, one or more co-developers, and one or more high contrast enhancing agents are also useful.
Suitable stabilizers that can be used alone or in combination include thiazolium salts as described in U.S. Pat. No. 2,131,038 (Brooker) and 2,694,716 (Allen), azaindenes as described in U.S. Pat. No. 2,886,437 (Piper), triazaindolizines as described in U.S. Pat. No. 2,444,605 (Heimbach), the urazoles described in U.S. Pat. No. 3,287,135 (Anderson), sulfocatechols as described in U.S. Pat. No. 3,235,652 (Kennard), the oximes described in GB 623,448 (Carrol et al.), polyvalent metal salts as described in U.S. Pat. No. 2,839,405 (Jones), thiuronium salts as described in U.S. Pat. No. 3,220,839 (Herz), palladium, platinum, and gold salts as described in U.S. Pat. No. 2,566,263 (Trirelli) and U.S. Pat. No. 2,597,915 (Damshroder), and the heteroaromatic mercapto compounds or heteroaromatic disulfide compounds described in EP 0 559 228B1 (Philip et al.).
Other useful antifoggants/stabilizers are described in U.S. Pat. No. 6,083,681 (Lynch et al.). Still other antifoggants are hydrobromic acid salts of heterocyclic compounds (such as pyridinium hydrobromide perbromide) as described in U.S. Pat. No. 5,028,523 (Skoug), benzoyl acid compounds as described in U.S. Pat. No. 4,784,939 (Pham), substituted propenenitrile compounds as described in U.S. Pat. No. 5,686,228 (Murray et al.), silyl blocked compounds as described in U.S. Pat. No. 5,358,843 (Sakizadeh et al.), the 1,3-diaryl-substituted urea compounds described copending and commonly assigned U.S. Patent Application Publication 2007/0117053 (Hunt et al.), and tribromo-methylketones as described in EP 0 600 587A1 (Oliffet al.).
Also useful as stabilizers for improving the post-processing print stability of the imaged material to heat during storage (known as “hot-dark print stability”) are the arylboronic acid compounds described in copending and commonly assigned U.S. Ser. No. 11/351,773 (filed on Feb. 10, 2006 by Chen-Ho and Sakizadeh).
The photothermographic materials preferably also include one or more polyhalogen stabilizers that can be represented by the formula Q-(Y)n—C(Z1Z2X) wherein, Q represents an alkyl, aryl (including heteroaryl) or heterocyclic group, Y represents a divalent linking group, n represents 0 or 1, Z1 and Z2 each represents a halogen atom, and X represents a hydrogen atom, a halogen atom, or an electron-withdrawing group. Particularly useful compounds of this type are polyhalogen stabilizers wherein Q represents an aryl group, Y represents (C═O) or SO2, n is 1, and Z1, Z2, and X each represent a bromine atom. Examples of such compounds containing —SO2CBr3 groups are described in U.S. Pat. No. 3,874,946 (Costa et al.), U.S. Pat. No. 5,369,000 (Sakizadeh et al.), U.S. Pat. No. 5,374,514 (Kirk et al.), U.S. Pat. No. 5,460,938 (Kirk et al.), U.S. Pat. No. 5,464,747 (Sakizadeh et al.) and U.S. Pat. No. 5,594,143 (Kirk et al.). Examples of such compounds include, but are not limited to, 2-tribromomethylsulfonyl-5-methyl-1,3,4-thiadiazole, 2-tribromomethylsulfonyl-pyridine, 2-tribromomethylsulfonylquinoline, and 2-tribromomethylsulfonyl-benzene. The polyhalogen stabilizers can be present in one or more layers in a total amount of from about 0.005 to about 0.01 mol/mol of total silver, and preferably from about 0.01 to about 0.05 mol/mol of total silver.
Stabilizer precursor compounds capable of releasing stabilizers upon application of heat during imaging can also be used, as described in U.S. Pat. No. 5,158,866 (Simpson et al.), U.S. Pat. No. 5,175,081 (Krepski et al.), 5,298,390 (Sakizadeh et al.), and U.S. Pat. No. 5,300,420 (Kenney et al.). Also useful are the blocked aliphatic thiol compounds described in U.S. Patent Application Publication 2006/0141403 (Ramsden et al.).
Compounds useful as toners are described in U.S. Pat. No. 3,080,254 (Grant, Jr.), U.S. Pat. No. 3,847,612 (Winslow), U.S. Pat. No. 4,123,282 (Winslow), U.S. Pat. No. 4,082,901 (Laridon et al.), U.S. Pat. No. 3,074,809 (Owen), U.S. Pat. No. 3,446,648 (Workman), 3,844,797 (Willems et al.), U.S. Pat. No. 3,951,660 (Hagemann et al.), U.S. Pat. No. 5,599,647 (Defieuw et al.) and GB 1,439,478 (AGFA).
The addition of development accelerators that increase the rate of image development and allow reduction in silver coating weight is also useful. Suitable development accelerators include phenols, naphthols, and hydrazine-carboxamides. Such compounds are described, for example, in Y. Yoshioka, K. Yamane, T. Ohzeki, Development of Rapid Dry Photothermographic Materials with Water-Base Emulsion Coating Method, AgX 2004: The International Symposium on Silver Halide Technology “At the Forefront of Silver Halide Imaging”, Final Program and Proceedings of IS&T and SPSTJ, Ventura, Calif., Sept. 13-15, 2004, pp. 28-31, Society for Imaging Science and Technology, Springfield, Va., U.S. Pat. No. 6,566,042 (Goto et al.), U.S. Patent Application Publications 2004/234906 (Ohzeki et al.), 2005/048422 (Nakagawa), 2005/118542 (Mori et al.), (Nakagawa), and 2006/0014111 (Goto).
Thermal solvents (or melt formers) can also be used, including combinations of such compounds (for example, a combination of succinimide and dimethylurea). Thermal solvents are compounds which are solids at ambient temperature but which melt at the temperature used for processing. The thermal solvent acts as a solvent for various components of the heat-developable photosensitive material, it helps to accelerate thermal development and it provides the medium for diffusion of various materials including silver ions and/or complexes and reducing agents. Known thermal solvents are disclosed in U.S. Pat. No. 3,438,776 (Yudelson), U.S. Pat. No. 5,064,753 (noted above) U.S. Pat. No. 5,250,386 (Aono et al.), U.S. Pat. No. 5,368,979 (Freedman et al.), U.S. Pat. No. 5,716,772 (Taguchi et al.), and U.S. Pat. No. 6,013,420 (Windender). Thermal solvents are also described in U.S. Pat. No. 7,169,544 (Chen-Ho et al.).
The photothermographic materials can also include one or more image stabilizing compounds that are usually incorporated in a “backside” layer. Such compounds can include phthalazinone and its derivatives, pyridazine and its derivatives, benzoxazine and benzoxazine derivatives, benzothiazine dione and its derivatives, and quinazoline dione and its derivatives, particularly as described in U.S. Pat. No. 6,599,685 (Kong). Other useful backside image stabilizers include anthracene compounds, coumarin compounds, benzophenone compounds, benzotriazole compounds, naphthalic acid imide compounds, pyrazoline compounds, or compounds described in U.S. Pat. No. 6,465,162 (Kong et al), and GB 1,565,043 (Fuji Photo).
Any conventional or useful phosphor can be used, singly or in mixtures. For example, useful phosphors are described in numerous references relating to fluorescent intensifying screens as well as U.S. Pat. No. 6,440,649 (Simpson et al.) and U.S. Pat. No. 6,573,033 (Simpson et al.) that are directed to photothermo-graphic materials. Some particularly useful phosphors are primarily “activated” phosphors known as phosphate phosphors and borate phosphors. Examples of these phosphors are rare earth phosphates, yttrium phosphates, strontium phosphates, or strontium fluoroborates (including cerium activated rare earth or yttrium phosphates, or europium activated strontium fluoroborates) as described in U.S. Patent Application Publication 2005/0233269 (Simpson et al.).
The one or more phosphors can be present in the photothermo-graphic materials in an amount of at least 0.1 mole per mole, and preferably from about 0.5 to about 20 mole, per mole of total silver in the photothermographic material. As noted above, generally, the amount of total silver is at least 0.002 mol/m2. While the phosphors can be incorporated into any imaging layer on one or both sides of the support, it is preferred that they be in the same layer(s) as the photosensitive silver halide(s) on one or both sides of the support
The photosensitive silver halide (when present), the non-photo-sensitive source of reducible silver ions, the reducing agent composition, and any other imaging layer additives are generally combined with one or more binders that are generally hydrophobic or hydrophilic in nature. Thus, either aqueous or organic solvent-based formulations can be used to prepare the thermally developable materials. Mixtures of either or both types of binders can also be used. It is preferred that the binder be selected from predominantly hydrophobic polymeric materials (at least 50 dry weight % of total binders).
Latex of methyl methacryl ate (70)-2-ethylhexyl acryl ate (20)-styrene (5)-acrylic acid (5).
Styrene-butadiene copolymer are particularly preferable as the polymer latex for use as a binder. The weight ratio of monomer unit for styrene to that of butadiene constituting the styrene-butadiene copolymer is preferably in the range of from 40:60 to 95:5. Further, the monomer unit of styrene and that of butadiene preferably account for 60% by weight to 99% by weight with respect to the copolymer. Moreover, the polymer latex contains acrylic acid or methacrylic acid, preferably, in the range from 1% by weight to 6% by weight, and more preferably, from 2% by weight to 5% by weight, with respect to the total weight of the monomer unit of styrene and that of butadiene. The preferred range of the molecular weight is the same as that described above.
Preferred latexes include styrene (50)-butadiene (47)-methacrylic acid (3), styrene (60)-butadiene (35)-divinylbenzene-methyl methacrylate (3)-methacrylic acid (2), styrene (70.5)-butadiene (26.5)-acrylic acid (3) and commercially available LACSTAR-3307B, 7132C, and Nipol Lx4l6. Such latexes are described in U.S. Patent Application Publication 2005/0221237 (Sakai et al.) that is incorporated herein by reference.
Hardeners for various binders may be present if desired. Useful hardeners are well known and include diisocyanate compounds as described in EP 0 600 586 Bi (Philip, Jr. et al.), vinyl sulfone compounds as described in U.S. Pat. No. 6,143,487 (Philip, Jr. et al.) and EP 0 640 589 A1 (Gathmann et al.), aldehydes and various other hardeners as described in U.S. Pat. No. 6,190,822 (Dickerson et al.). The hydrophilic binders used in the thermally developable materials are generally partially or fully hardened using any conventional hardener. Useful hardeners are well known and are described, for example, in T. H. James, The Theory of the Photographic Process, Fourth Edition, Eastman Kodak Company, Rochester, N.Y., 1977, Chapter 2, pp. 77-8.
An organic solvent-based coating formulation for the thermo-graphic and photothermographic emulsion layer(s) can be prepared by mixing the various components with one or more binders in a suitable organic solvent system that usually includes one or more solvents such as toluene, 2-butanone (methyl ethyl ketone), acetone, or tetrahydrofuran, or mixtures thereof. Methyl ethyl ketone is a preferred coating solvent.
The thermally developable materials may also include a surface protective layer over the one or more emulsion layers. Layers to reduce emissions from the material may also be present, including the polymeric barrier layers described in U.S. Pat. No. 6,352,819 (Kenney et al.), U.S. Pat. No. 6,352,820 (Bauer et al.), U.S. Pat. No. 6,420,102 (Bauer et al.), U.S. Pat. No. 6,667,148 (Rao et al.), and U.S. Pat. No. 6,746,831 (Hunt).
Mottle and other surface anomalies can be reduced by incorporating a fluorinated polymer as described, for example, in U.S. Pat. No. 5,532,121 (Yonkoski et al.) or by using particular drying techniques as described, for example in U.S. Pat.5,621,983 (Ludemann et al.).
Thermographic and photothermographic formulations of can be coated by various coating procedures including wire wound rod coating, dip coating, air knife coating, curtain coating, slide coating, or extrusion coating using hoppers of the type described in U.S. Pat. No. 2,681,294 (Beguin). Layers can be coated one at a time, or two or more layers can be coated simultaneously by the procedures described in U.S. Pat. No. 2,761,791 (Russell), U.S. Pat. No. 4,001,024 (Dittman et al.), U.S. Pat. No. 4,569,863 (Keopke et al.), U.S. Pat. No. 5,340,613 (Hanzalik et al.), U.S. Pat. No. 5,405,740 (LaBelle), U.S. Pat. No. 5,415,993 (Hanzalik et al.), U.S. Pat. No. 5,525,376 (Leonard), U.S. Pat. No. 5,733,608 (Kessel et al.), U.S. Pat. No. 5,849,363 (Yapel et al.), U.S. Pat. No. 5,843,530 (Jerry et al.), and U.S. Pat. No. 5,861,195 (Bhave et al.), and GB 837,095 (Ilford). A typical coating gap for the emulsion layer can be from about 10 to about 750 μm, and the layer can be dried in forced air at a temperature of from about 20° C. to about 100° C. It is preferred that the thickness of the layer be selected to provide maximum image densities greater than about 0.2, and more preferably, from about 0.5 to 5.0 or more, as measured by an X-rite Model 361/V Densitometer equipped with 301 Visual Optics, available from X-rite Corporation, (Granville, Mich.).
The thermally developable materials can include one or more antistatic or conductive layers agents in any of the layers on either or both sides of the support. Conductive components include soluble salts, evaporated metal layers, or ionic polymers as described in U.S. Pat. No. 2,861,056 (Minsk) and U.S. Pat. No. 3,206,312 (Sterman et al.), insoluble inorganic salts as described in U.S. Pat. No. 3,428,451 (Trevoy), electroconductive underlayers as described in U.S. Pat. No. 5,310,640 (Markin et al.), electronically-conductive metal antimonate particles as described in U.S. Pat. No. 5,368,995 (Christian et al.), and electrically-conductive metal-containing particles dispersed in a polymeric binder as described in EP 0 678 776 Al (Melpolder et al.). Particularly useful conductive particles are the non-acicular metal antimonate particles used in a buried backside conductive layer as described and in U.S. Pat. No. 6,689,546 (LaBelle et al.), U.S. Pat. No. 7,018,787 (Ludemann et al.), and U.S. Pat. 7,022,467 (Ludemann et al.) and in U.S. Patent Application Publications 2006/0046215 (Ludemann et al.), 2006/0046932, and 2006/0093973 (Ludemann et al.).
Still other conductive compositions include one or more fluoro-chemicals each of which is a reaction product of Rf—CH2CH2—SO3H with an amine wherein Rf comprises 4 or more fully fluorinated carbon atoms as described in U.S. Pat. No. 6,699,648 (Sakizadeh et al.). Additional conductive compositions include one or more fluorochemicals described in more detail in U.S. Pat. No. 6,762,013 (Sakizadeh et al.).
Thermal development conditions will vary, depending on the construction used but will typically involve heating the imagewise exposed photo-thermographic material at a suitably elevated temperature, for example, at from about 50° C. to about 250° C. (preferably from about 80° C. to about 200° C. and more preferably from about 100° C. to about 200° C.) for a sufficient period of time, generally from about 1 to about 120 seconds. Heating can be accomplished using any suitable heating means such as contacting the material with a heated drum, plates, or rollers, or by providing a heating resistance layer on the rear surface of the material and supplying electric current to the layer so as to heat the material. A preferred heat development procedure for photothermographic materials includes heating within a temperature range of from 110 to 150° C for 25 seconds or less, for example, at least 3 and up to 25 seconds (and preferably for 20 seconds or less) to develop the latent image into a visible image having a maximum density (Dmax) of at least 3.0. Line speeds during development of greater than 61 cm/min, such as from 61 to 200 cm/min can be used.
Thermal development of either thermographic or photothermo-graphic materials is carried out with the material being in a substantially water-free environment and without application of any solvent to the material.
The thermographic and photothermographic materials can be sufficiently transmissive in the range of from about 350 to about 450 nm in non-imaged areas to allow their use in a method where there is a subsequent exposure of an ultraviolet or short wavelength visible radiation sensitive imageable medium. The thermally-developed materials absorb ultraviolet or short wavelength visible radiation in the areas where there is a visible image and transmit ultraviolet or short wavelength visible radiation where there is no visible image. The thermally-developed materials may then be used as a mask and positioned between a source of imaging radiation (such as an ultraviolet or short wavelength visible radiation energy source) and an imageable material that is sensitive to such imaging radiation, such as a photopolymer, diazo material, photoresist, or photosensitive printing plate. Exposing the imageable material to the imaging radiation through the visible image in the exposed and heat-developed thermographic or photothermographic material provides an image in the imageable material. This method is particularly useful where the imageable medium comprises a printing plate and the thermally developable material serves as an image-setting film.
PARALOID® A-2 1 is an acrylic copolymer available from Rohm and Haas (Philadelphia, Pa.).
PIOLOFORM® BL-16 is reported to be a polyvinyl butyral resin having a glass transition temperature of about 84° C. PIOLOFORM® BM- 18 is reported to be a polyvinyl butyral resin having glass transition temperature of about 70° C. Both are available from Wacker Polymer Systems (Adrian, Mich.).
Comparative Compound 1 (CC-1) has the following structure
The following example demonstrates the improvement in hot-dark print stability using a combination of trisphenol and bisphenol reducing agents.
A photothermographic emulsion formulation was prepared at 67° F. (19.4° C.) containing 174 parts of the above preformed silver halide at 28.2% solids, silver carboxylate soap dispersion. To this formulation was added 1.6 parts of a 15% solution of pyridinium hydrobromide perbromide in methanol, with stirring. After 45 minutes of mixing, 2.1 parts of an 11% zinc bromide solution in methanol was added. Stirring was continued and after 30 minutes, a solution of 0.15 parts 2-mercapto-5-methylbenzimidazole, 0.007 parts of Sensitizing Dye A, 1.7 parts of 2-(4-chlorobenzoyl)benzoic acid, 10.8 parts of methanol, and 3.8 parts of MEK were added. After stirring for 75 minutes, the temperature was lowered to 50° F. (10° C.), and 26.15 parts of PIOLOFORM® BM-18 and 19.8 parts of PIOLOFORM® BL-16 were added. Mixing was continued for another 15 minutes.
Solution A containing: Antifoggant AF-A 0.80 parts Tetrachlorophthalic acid (TCPA) 0.37 parts 4-Methylphthalic acid (4-MPA) 0.71 parts MEK 21 parts Methanol 0.36 parts Solution B containing: DESMODUR ® N3300 Solution 0.66 parts in 0.33 parts MEK Solution C containing: Phthalazine (PHZ) Solution 1.3 parts in 6.3 parts MEK
To 25.5 parts of the completed emulsion formulation was added the amount of reducing agent or reducing agent mixture shown in TABLE IV, and enough additional MEK for the emulsion to contain 37.1% solids.
Overcoat Formulation-A:
Overcoat Formulation-A was prepared by mixing the following materials:
MEK 329.04 parts PARALOID ® A-21 2.34 parts CAB 171-15S 25.57 parts Vinyl Sulfone VS-1 1.18 parts, 82.89% active (0.98 parts net) Benzotriazole (BZT) 0.72 parts Acutance Dye AD-1 0.48 parts Antifoggant AF-B 0.64 parts DESMODUR ® N3300 Solution 1.92 parts, in 0.94 parts MEK Tinting Dye TD-1 0.016 parts
Overcoat Formulation-B:
Overcoat Formulation-B was prepared by mixing the following materials:
MEK 329.04 parts PARALOID ® A-21 2.34 parts CAB 171-15S 25.57 parts Vinyl Sulfone VS-1 1.18 parts, 82.89% active (0.98 parts net) Benzotriazole (BZT) 0.72 parts Acutance Dye AD-1 0.29 parts Antifoggant AF-B 0.64 parts DESMODUR ® N3300 Solution 1.92 parts, in 0.94 parts MEK Tinting Dye TD-1 0.021 parts
The photothermographic emulsion and overcoat formulations were simultaneously coated onto a 7 mil (178 μm) polyethylene terephthalate support, tinted blue with support dye SD-1. An automated dual knife coater equipped with an in-line dryer was used. Immediately after coating, samples were dried in a forced air oven at between 90 and 97° C. for between 4 and 7 minutes. The photo-thermographic emulsion formulation was coated to obtain a coating weight of between about 1.65 and 2.00 g of total silver/m2. The overcoat formulation was coated to obtain about a dry coating weight of about 0.2 g/ft2 (2.2 g/m2) and an absorbance in the imaging layer of between 0.9 and 1.35 at 810 μm.
Samples of each photothermographic material were cut into strips, exposed with a laser sensitometer at 810 nm, and thermally developed to generate continuous tone wedges with image densities varying from a minimum density (Dmin) to a maximum density (Dmax) possible for the exposure source and development conditions. Development was carried out on a 6 inch diameter (15.2 cm) heated rotating drum. The strip contacted the drum for 210 degrees of its revolution, about 11 inches (28 cm). Samples were developed at 122.5° C. for 15 seconds at a rate of 0.733 inches/sec (112 cm/min) A strip sample of each photothermographic material was scanned using a computerized densitometer equipped with both a visible filter and a blue filter having peak transmission at about 440 nm. The Dmin, Dmax, Silver Efficiency (Dmax/Silver Coating Weight in g/m2), AC-1, Speed-2, and hot-dark print stability were measured using the blue filter. The data, shown below in TABLE IV, demonstrate that the reducing agent combinations to provide improved Silver Efficiency.
Silver efficiency was calculated for each sample by dividing Dmax by silver coating weight in g/m2. The silver coating weight of each film sample was measured by X-ray fluorescence using commonly known techniques.
Evaluation of Hot-Dark Print Stability:
A continuous tone wedge strip sample of each developed photo-thermographic coating prepared above, was illuminated with fluorescent lighting for 3 hours at 70° F. (21° C.) and 50% relative humidity. The illumination at the surface of each strip sample was 90 to 120 foot candles (968 to 1291 lux). Each sample was then re-scanned using the same computer densitometer and using the blue filter having a peak transmittance at about 440 nm. The Dmin-Blue, Dmax-Blue, and the point on the strip having an optical density of approximately 1.2 (OD-Blue) were recorded.
A set of processed samples was then stacked together and tightly double-bagged in two high-density, flat-black polyethylene bags. Three strips of polyethylene terephthalate support tinted blue with support dye SD-1 were placed above and below the stack of film samples. The bagged samples were then placed in an oven and heated at 68-74° C. for 3 hours. Upon cooling to room temperature, the samples were removed from the bag and re-scanned using the same densitometer and blue filter. The changes in Dmin-Blue (ΔDmin-Blue), Dmax-Blue, (ΔDmax-Blue), and OD-Blue (ΔOD-Blue) were recorded to determine the hot-dark print stability.
The results, shown below in TABLE V demonstrate the unique ability of reducing agent combinations to provide improved hot-dark print stability.
TABLE IV Silver Efficiency Reducing Amount (Dmax/Ag Absorbance Initial Initial Sample Agent (parts) Overcoat Coating Wt.) 810 nm Dmin Dmax Speed-2 AC-1
1-1-Comparative III-7 0.89 A 1.93 1.05 0.216 3.73 1.69 3.59 1-2-Inventive I-2 + III-4 0.45 A 2.05 0.93 0.217 3.91 1.76 3.87 0.25
TABLE V ΔDmin-Blue ΔOD-Blue at ΔDmax-Blue After 3 Hours 1.2 After 3 Hours After 3 Hours Hot-Dark Hot-Dark Hot-Dark Sample Print Stability Print Stability Print Stability
1-1-Comparative 0.057 0.708 0.71 1-2-Inventive 0.045 0.246 0.25
Photothermographic materials were prepared, coated, imaged, and evaluated for hot-dark print stability substantially as described in Example 1 but incorporating combinations of trisphenol and monophenol reducing agents.
The results, shown below in TABLES VI and VII demonstrate the unique ability of reducing agent combinations to provide improved silver efficiency and hot-dark print stability.
TABLE VI Reducing Amount Absorbance Initial Initial Silver Efficiency Sample Agent (parts) Overcoat 810 nm Dmin Dmax (Dmax/Ag Ct. Wt.) Speed-2 AC-1
2-1-Comparative III-7 0.89 A 1.10 0.213 3.85 1.96 1.72 3.67 2-2-Inventive I-2 + II-8 0.60 B 1.19 0.212 3.85 2.16 1.73 3.92 0.70 2-3-Inventive I-3 + II-8 0.81 B 1.19 0.213 3.94 2.21 1.70 4.00 0.70 2-4-Inventive I-3 + II-8 0.81 A 0.95 0.210 3.93 2.23 1.74 4.71 0.70 2-5-Inventive I-1 + II-8 0.73 B 1.19 0.213 3.71 2.07 1.50 3.23 0.70 2-6-Inventive I-1 + II-8 0.73 A 0.95 0.209 3.68 2.13 1.56 3.63 0.70
TABLE VII ΔDmin-Blue ΔOD-Blue at ΔDmax-Blue After 3 Hours 1.2 After 3 Hours After 3 Hours Hot-Dark Hot-Dark Hot-Dark Sample Print Stability Print Stability Print Stability
2-1-Comparative 0.036 0.466 0.47 2-2-Inventive 0.015 0.133 0.16 2-3-Inventive 0.010 0.089 0.15 2-4-Inventive 0.011 0.073 0.16 2-5-Inventive 0.011 0.045 0.17 2-6-Inventive 0.010 0.023 0.12
Photothermographic materials were prepared, coated, imaged, and evaluated for hot-dark print stability substantially as described in Example 1. Comparative Sample 3-1 contained only a bisphenol reducing agent, Comparative Samples 3-2 and 3-3 contained a mixture of a bisphenol and a monophenol reducing agent. Inventive Samples 3-4 and 3-5 contained a mixture of a trisphenol and monophenol reducing agent.
The results, shown below in TABLES VIII and IX demonstrate the unique ability of reducing agent combinations comprising a trisphenol to provide improved hot-dark print stability. Inventive Samples 3-4 and 3-5 showed higher Silver Efficiency and less change in Dmin-Blue, Dmax-Blue, and Density at 1.2 OD-Blue than comparative samples not containing a trisphenol developer.
TABLE VIII Reducing Amount Absorbance Initial Initial Silver Efficiency Sample Agent (parts) Overcoat 810 nm Dmin Dmax (Dmax/Ag Ct. Wt.) Speed-2 AC-1
3-1-Comparative III-7 0.89 A 1.04 0.225 3.74 1.95 1.73 3.57 3-2-Comparative III-7 + II-8 0.71 A 0.98 0.215 3.78 1.96 1.67 3.87 0.35 3-3-Comparative III-7 + II-8 0.71 A 1.03 0.216 3.60 1.92 1.64 3.73 0.70 3-4-Inventive I-2 + II-8 0.60 A 0.99 0.216 3.68 2.07 1.71 3.90 0.35 3-5-Inventive I-2 + II-8 0.60 A 0.94 0.219 3.76 2.12 1.70 3.99 0.70
TABLE IX ΔDmin-Blue ΔOD-Blue ΔDmax-Blue After 3 Hours at 1.2 After 3 Hours After 3 Hours Hot-Dark Hot-Dark Hot-Dark Sample Print Stability Print Stability Print Stability
3-1-Comparative 0.025 0.309 0.33 3-2-Comparative 0.025 0.460 0.51 3-3-Comparative 0.029 0.495 0.61 3-4-Inventive 0.012 0.158 0.22 3-5-Inventive 0.016 0.145 0.28
Photothermographic materials were prepared, coated, imaged, and evaluated for hot-dark print stability substantially as described in Example 1. Comparative Sample 4-1 contained only a bisphenol reducing agent, Inventive Samples 4-2 and 4-3 contained a mixture of a trisphenol and monophenol reducing agent. In Comparative Sample 4-1, the reducing agent composition was added to 25.5 parts of the emulsion formulation. In Inventive Samples 4-2 and 4-3, the reducing agent composition was added to the full emulsion formulation The results, shown below in TABLES X and XI demonstrate the unique ability of reducing agent combinations comprising a trisphenol to provide improved Silver Efficiency, Image Tone, and hot-dark print stability. Inventive Samples 4-2 and 4-3 showed higher Silver Efficiency and less change in Dmin-Blue, Dmax-Blue, and Density at 1.2 OD-Blue than the Comparative Sample. Image tone, measured at a visible density of 2.0, is the difference of the blue filter density from 2.0. The larger Image Tone values for the Inventive Samples 4-2 and 4-3 indicate a bluer image than the Comparative Sample.
TABLE X Silver Efficiency Image Reducing Amount Absorbance Initial Initial (Dmax/Ag Ct. Tone Sample Agent (parts) Overcoat 810 nm Dmin Dmax Wt.) at D = 2.0 Speed-2 AC-1
4-1-Comparative III-7 0.89 A 1.01 0.218 3.83 1.96 0.190 1.76 3.81 4-2-Inventive I-2 + II-8 6.34 A 0.96 0.218 3.89 2.19 0.248 1.82 4.22 7.48 4-3-Inventive I-2 + II-8 6.34 B 1.17 0.220 3.91 2.15 0.232 1.78 3.93 7.48
TABLE XI ΔDmin-Blue ΔOD-Blue ΔDmax-Blue After 3 Hours at 1.2 After 3 Hours After 3 Hours Hot-Dark Hot-Dark Hot-Dark Sample Print Stability Print Stability Print Stability
4-1-Comparative 0.028 0.330 0.35 4-2-Inventive 0.015 0.092 0.17 4-3-Inventive 0.012 0.064 0.13
A preformed silver halide, silver carboxylate soap dispersion, was prepared in similar fashion to that described in U.S. Pat. No. 5,939,249 (noted above) and as described in Example 1.
A photothermographic emulsion formulation was prepared at 67° F. (19.4° C.) containing 174 parts of the above preformed silver halide, silver carboxylate soap dispersion and 4.6 parts of MEK. To this formulation was added 1.6 parts of a 15% solution of pyridinium hydrobromide perbromide in methanol, with stirring. After 45 minutes of mixing, 2.1 parts of an 11% zinc bromide solution in methanol was added. Stirring was continued and after 30 minutes, a solution of 0.18 parts 2-mercapto-5-methylbenzimidazole, 0.009 parts of Sensitizing Dye A, 2.0 parts of 2-(4-chlorobenzoyl)benzoic acid, 10.8 parts of methanol, and 3.4 parts of MEK were added. After stirring for 75 minutes, the temperature was lowered to 50° F. (10° C.), and 46.16 parts of PIOLOFORM® BL-16 were added. Mixing was continued for another 15 minutes.
Reducing agent or reducing agent mixtures were added to separately prepared photothermographic emulsion formulations. Mixing was continued for another 5 minutes.
TABLE XII Sample Reducing Agent(s) Amount
5-1 Comparative Compound I-2 4.21 g 5-2 Inventive Compound I-2 and 4.21 g Compound II-9 9.48 g 5-3 Inventive Compound I-2 and 4.21 g Compound II-17 6.71 g 5-4 Inventive Compound I-2 and 4.21 g Compound II-8 7.54 g
Solution A containing: Antifoggant AF-A 0.80 parts Tetrachlorophthalic acid (TCPA) 0.37 parts 4-Methylphthalic acid (4-MPA) 0.71 parts MEK 21 parts Methanol 0.36 parts Solution B containing: DESMODUR ® N3300 Solution 0.66 parts in 0.33 parts MEK Solution C containing: Phthalazine (PHZ) 1.4 parts in 6.3 parts MEK
Overcoat Formulation-C:
Overcoat Formulation-C was prepared by mixing the following materials:
MEK 458.1 parts PARALOID ® A-21 2.93 parts CAB 171-15S 31.95 parts Vinyl Sulfone VS-1 1.62 parts, 80.8% active (0.1.30 parts net) Benzotriazole (BZT) 0.91 parts Acutance Dye AD-1 0.91 parts Antifoggant AF-B 0.8 parts DESMODUR ® N3300 Solution 2.4 parts, in 0.76 parts MEK Tinting Dye TD-1 0.022 parts
Sample 5-1 contained only a trisphenol reducing agent. It served as a control. Samples 5-2, 5-3 and 5-4 contained a mixture of reducing agents.
The photothermographic emulsion and overcoat formulations were simultaneously coated onto a 7 mil (178 μm) polyethylene terephthalate support, tinted blue with support dye SD-1. An automated dual knife coater equipped with an in-line dryer was used. Immediately after coating, samples were dried in a forced air oven at between 90 and 97° C. for between 4 and 6 minutes. The photo-thermographic emulsion formulation was coated to obtain a coating weight of between about 1.6 and 2.0 g of total silver/m2. The overcoat formulation was coated to obtain a dry coating weight of about 0.2 g/ft2 (2.2 g/m2) and an absorbance in the imaging layer between 0.9 and 1.0 at 815 nm.
Samples of each photothermographic material were cut into strips and imaged with a laser sensitometer at 810 nm, and thermally developed as described in Example 1.
A strip sample of each photothermographic material was scanned using a computerized densitometer equipped with both a visible filter and a blue filter having peak transmission at about 440 nm as described in Example 1. TABLE XIII shows the values for Dmin, Dmax, Speed-2, and. Silver Efficiency for these samples using a visual filter.
The results, shown below in Table XIII, demonstrate that the mixtures of a trisphenol reducing agent with a monophenol reducing agent provide improved Silver Efficiency when compared to the use of a trisphenol reducing agent alone.
TABLE XIII Silver Coating Wt. Silver Efficiency Sample Dmin Dmax Speed-2 (g/m2) (Dmax/Ag Ct. Wt.)
5-1 Comparative 0.221 2.620 1.726 1.87 1.40 5-2 Inventive 0.217 3.411 1.861 1.69 2.02 5-3 Inventive 0.216 3.738 1.744 1.77 2.11 5-4 Inventive 0.221 3.978 1.782 1.80 2.21
Photothermographic materials were prepared in the same manner as described in Example 5 using the amounts of reducing agents shown below in TABLE XIV.
TABLE XIV Sample Reducing Agent(s) Amount
6-1 Comparative Compound III-7 9.52 g 6-2-Inventive Compound I-3 5.75 g Compound II-8 6.5 g 6-3-Comparative Compound CC-1 5.16 Compound II-8 6.5 g
Samples were coated, dried, imaged, and evaluated as described in Example 1. TABLE XV shows the sensitometric values for Dmin, Dmax, Speed-2, and Silver Efficiency for each sample using a visual filter. The data demonstrate that Inventive Sample 6-2 has a higher Silver Efficiency than Comparative Sample 6-1. Although Comparative Sample 6-3 showed high Silver Efficiency, it also has unacceptably high Dmin.
TABLE XV Silver Coating Wt. Silver Efficiency Sample Dmin Dmax Speed-2 (g/m2) (Dmax/Ag Ct. Wt.)
6-1 Comparative 0.218 3.402 1.758 1.62 2.1 6-2 Inventive 0.212 3.674 1.675 1.65 2.23 6-3 Comparative 0.287 3.748 2.007 1.71 2.19
A photothermographic emulsion formulation was prepared at 67° F. (19.4° C.) containing 174 parts of the above preformed silver halide, silver carboxylate soap dispersion and 4.6 parts of MEK. To this formulation was added 1.6 parts of a 15% solution of pyridinium hydrobromide perbromide in methanol, with stirring. After 45 minutes of mixing, 2.1 parts of an 11% zinc bromide solution in methanol was added. Stirring was continued and after 30 minutes, a solution of 0.18 parts 2-mercapto-5-methylbenzimidazole, 0.009 parts of Sensitizing Dye A, 2.0 parts of 2-(4-chlorobenzoyl)benzoic acid, 10.8 parts of methanol, and 3.4 parts of MEK were added. After stirring for 75 minutes, the temperature was lowered to 50° F. (10° C.), and 26.2 parts of PIOLOFORM® BM-18, 19.8 parts of PIOLOFORM® BL-16, and 50.9 parts of MEK were added. Mixing was continued for another 15 minutes.
Solution A containing: Antifoggant AF-A 0.80 parts Tetrachlorophthalic acid (TCPA) 0.37 parts 4-Methylphthalic acid (4-MPA) 0.71 parts MEK 21 parts Methanol 0.36 parts Solution B containing: DESMODUR ® N3300 Solution 0.66 parts in 0.33 parts MEK Solution C containing: Phthalazine (PHZ) 1.32 parts in 6.3 parts MEK
To 27.8 parts of the completed emulsion formulation was added the amount of reducing agent or reducing agent mixture shown in TABLE XVI.
TABLE XVI Amount Sample Reducing Agent(s) (parts)
7-1 Comparative Compound III-1 0.87 Compound II-8 0.67 7-2-Inventive Compound I-2 0.48 Compound III-1 0.27 Compound II-8 0.67 7-3-Comparative Compound I-3 0.41 7-4-Inventive Compound I-2 0.31 Compound III-4 0.21 Compound II-8 0.67
Overcoat Formulation-D:
Overcoat Formulation-D was prepared by mixing the following materials:
MEK 292 parts PARALOID ® A-21 12.1 parts CAB 171-15S 132 parts Vinyl Sulfone VS-1 0.96 parts, 80.8% active (0.78 parts net) Benzotriazole (BZT) 0.29 parts Acutance Dye AD-1 0.50 parts Antifoggant AF-B 0.51 parts DESMODUR ® N3300 Solution 1.54 parts, in 0.76 parts MEK Tinting Dye TD-1 0.090 parts
The photothermographic emulsion and overcoat formulations were simultaneously coated onto a 7 mil (178 μm) polyethylene terephthalate support, tinted blue with support dye SD-1. An automated dual knife coater equipped with an in-line dryer was used. Immediately after coating, samples were dried in a forced air oven at 85° C. for about 5 minutes. The photothermographic emulsion formulation was coated to obtain a coating weight of between about 1.6 and 1.7 g of total silver/m2. The overcoat formulation was coated to obtain a dry coating weight of about 0.2 g/ft2 (2.2 g/m2) and an absorbance in the imaging layer between 0.90 and 1.00 at 815 nm.
Samples of each photothermographic material were cut into strips, imaged with a laser sensitometer at 810 nm and developed as described in Example 1.
A strip sample of each photothermographic material was scanned using a computerized densitometer equipped with both a visible filter and a blue filter having peak transmission at about 440 nm. Image tone, measured at a visible density of 2.0, is the difference of the blue filter density from 2.0. Larger Image Tone values indicate a bluer image.
The data, shown below in TABLE XVII, demonstrates the advantage of reducing agent combinations comprising a trisphenol to provide improved Silver Efficiency, Image Tone, and hot-dark print stability.
TABLE XVII Silver Efficiency Initial Initial (Dmax/Ag Ct. Image Tone at ΔOD-Blue at 1.2 After 3 Hours Sample Dmin Dmax Wt.) Speed-2 D = 2.0 Hot-Dark Print Stability
7-1-Comparative 0.228 3.73 2.26 1.82 0.055 1.36 7-2-Inventive 0.222 3.78 2.24 1.77 0.235 0.329 7-3-Comparative 0.213 3.55 2.22 1.70 0.154 0.575 7-4-Inventive 0.219 3.73 2.24 1.71 0.213 0.291
1. A thermally developable material comprising a support having on at least one side thereof, one or more thermally developable imaging layers comprising in reactive association: wherein L1, L2, and L3 are independently a methylene group or a mono-substituted methylene group.
b. a combination of reducing agents for said reducible silver ions, and
wherein said combination of reducing agents consists essentially of at least one trisphenol represented by the following Structure (I), and
R1 and R2 are independently substituted or unsubstituted primary or secondary alkyl groups having 1 to 8 carbon atoms. R3, R4, R5, R19, and R20 are independently substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms. R6, R7, R8, R9, R10, R11, R15, R16, R21, R22, R23, and R24 are independently hydrogen, or substituted or unsubstituted methyl, ethyl, or methoxy groups, or chioro groups. R12, R13, R17, and R8 are independently substituted or unsubstituted primary, secondary, or tertiary alkyl groups haying 1 to 7 carbon atoms, R4 is a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, and n is 1 to 4. provided that when n is 2 or greater, L4 is a single bond or a linking group that is attached to any of R14, R15, or R16.
3. The thermally developable material of claim 1 wherein L1, L2, and L3 are unsubstituted methylene groups,
R1 and R2 are the same substituted or unsubstituted primary or secondary alkyl groups,
R3, R4, R5, R9, and R20 are the same substituted or unsubstituted methyl or ethyl groups,
R6, R7,R8, R9, R10, R11, R15, R16, R21, R22, R23, and R24 are independently hydrogen or unsubstituted methyl groups,
R14 is a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms.
4. The thermally developable material of claim 3 wherein R14 is a CH2CH2(C=O)- group, n is 4, and L4 is a (-OCH2)4C- group.
5. The thermally developable material of claim 1 wherein the molar ratio of the reducing agent of Structure (I) to the total reducing agents of Structure (II) and (III), is from about 0.1:1 to about 50:1.
6. The thermally developable material of claim 1 that is a photothermographic material and further comprises a photosensitive silver halide.
7. The thermally developable material of claim 1 further comprising a high contrast enhancing agent, co-developer, or both.
8. The thermally developable material of claim 7 wherein said high contrast enhancing agent or co-developer is a substituted acrylonitrile compound, a trityl hydrazide or formyl phenyl hydrazide, hydroxylamine, alkanolamine, ammonium phthalamate, hydroxamic acid, N-acylhydrazine, or hydrogen atom donor compound.
9. The thermally developable material of claim 1 wherein the total amount of silver is less than 1.9 g/m2.
11. The thermally developable material of claim 1 wherein the molar ratio of all reducing agents of Structure (I) through (III) to total silver is from about 0.05 mol/mol of total silver to about 0.5 mol/mol of total silver.
12. The thermally developable material of claim 1 wherein the reducing agent of Structure (I) is present in an amount of from about 0.5 to about 30 weight % and the total amount of reducing agents from Structure (I), (II), and (III) is from about 1 to about 45 weight %.
13. A photothermographic material comprising a support having on at least one side thereof, one or more thermally developable imaging layers comprising in reactive association: wherein L1, L2, and L3 are independently a methylene group or a mono-substituted methylene group.
c. a combination of reducing agents for said reducible silver ions, and
R1 and R2 are independently substituted or unsubstituted primary or secondary alkyl groups having 1 to 8 carbon atoms.
R3, R4, R5, R19, and R20 are independently substituted or unsubstituted alkyl groups having 1 to 6 carbon atoms.
R6, R7, R8, R9, R10, R11, R15, R16, R21, R22, R23, and R24 are independently hydrogen, or substituted or unsubstituted methyl, ethyl, or methoxy groups, or chloro groups.
R12, R13, R17 and R18 are independently substituted or unsubstituted primary, secondary, or tertiary alkyl groups haying 1 to 7 carbon atoms
14. A black-and-white, organic solvent based photothermographic material comprising a support and having on at least one side thereof a photothermographic layer and comprising, in reactive association:
wherein the total amount of silver is present in an amount of at least 1 g/m2 and less than or equal to 2.5 g/m2.
said combination of reducing agents consists essentially of combination of either or both of Compounds I-2 and I-3 with either or both of Compounds II-8 and ii-17,
a combination of either or both of Compounds I-2 and I-3 with either or both of Compounds III-1 and III-4, or
a combination of either or both of Compounds I-2 and I-3 with either or both of Compounds II-8 and II-17 and either or both of Compounds III-1 and III-4,
a high contrast enhancing agent that is optionally present in an amount of from about 0.001 to about 0.5 g/m2,
the structural formulae of compounds I-2, I-3, II-8, II-17, III-1, and III-4 represented by:
15. The photothermographic material of claim 14 wherein said co-developer is a substituted acrylonitrile.
16. The photothermographic material of claim 14 wherein said high contrast enhancing agent is a hydroxylamine, alkanolamine, ammonium phthalamate, hydroxamic acid, N-acylhydrazine, or hydrogen atom donor compound.
B) simultaneously or sequentially, heating said exposed photothermo-graphic material to develop said latent image into a visible image.
18. The method of claim 17 wherein said development is carried out for 25 seconds or less.
19. The method of claim 17 wherein said imagewise exposing is carried out using laser imaging at from about 600 to about 1200 nm.
20. A method of forming a visible image comprising thermal imaging of the material of claim 1 that is a thermographic material.
Inventors: Stacy M. Ulrich (Dresser, WI), Doreen C. Lynch (Afton, MN), Takuzo Ishida (Woodbury, MN), Chaofeng Zou (Maplewood, MN), Paul G. Skoug (Stillwater, MN), William D. Ramsden (Afton, MN)
Application Number: 11/507,550
Current U.S. Class: And Inorganic Silver Compound (430/619)