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
  • G03C1/72—Photosensitive compositions not covered by the groups G03C1/005 - G03C1/705
  • G03C1/73—Photosensitive compositions not covered by the groups G03C1/005 - G03C1/705 containing organic compounds
  • G03C1/732—Leuco dyes
• • 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
  • G03C1/52—Compositions containing diazo compounds as photosensitive substances
  • G03C1/61—Compositions containing diazo compounds as photosensitive substances with non-macromolecular additives

Definitions

• a novel light sensitive, heat developable imaging system incorporating a diazonium salt and a leuco dye in a binder is disclosed.
• the system is useful, for example, as a microfilm duplicating sheet or a heat sensitive recording material.
• U.S. Patent 3,390,997 discloses a light-sensitive admixture of an alkylthio, benzylthio, 2-phenylhydrazino or alkoxycarbonyl derivative of a triphenylmethane compound (a "leuco dye") and a selected non-volatile nitrogen-containing compound which functions as a photooxidant useful as an imaging system.
• the patent does not disclose the use of diazonium salts or materials which contain a pentavalent nitrogen atom.
• the light sensitive compounds of the present invention differ significantly from those of the patent which contain only trivalent nitrogen atoms.
• the present invention requires elevated temperatures, 82°C to 193°C, for image development, whereas the patent disclosure is of a room temperature developing system.
• the present invention relates to a light sensitive, heat developable imaging system comprising a polymeric binder resin, a leuco dye, and a diazonium salt.
• a polymeric binder resin e.g., polyethylene glycol dimethacrylate copolymer
• a leuco dye e.g., polyethylene glycol dimethacrylate copolymer
• a diazonium salt e.g., organic or inorganic acid
• oxidizing anion including nitrate ion
• nitrate ion is a necessary component of the present invention as it is in assignee's copending application mentioned above. If any nitrate ion is present, it is in amounts of less than 0.1 mole nitrate/1.0 mole dye. Other oxidizing anions and compounds may be present in greater or lesser amounts, but are not essential in the practice of the present invention.
• the leuco dye a clear to faintly colored material
• the diazonium salt and thepolymeric binder resin are incorporated in a solvent system and cast on any substrate such as paper, polymeric film such as polyester, glass, metal, ceramics and the like. Upon irradiation by light, the diazonium salt is destroyed.
• reaction appears to be an oxidation of the leuco dye during heat development by the diazonium salt which has not been decomposed by incident radiation.
• the present invention relates to a light sensitive, heat developable layer comprising a polymeric binder, a le. o dye, and a photosensitive diazonium salt. These ingredients are preferably in a homogeneous or molecular mixture with each other.
• the Binder Any natural or synthetic polymeric binder may be used in the practice of the present invention.
• Organic polymeric resins preferably thermoplastic resins (although thermoset resins may be used), are generally preferred.
• the most preferred resins are polyvinyl acetate and polyvinyl chloride copolymers.
• Such resins as polyvinyl acetals, polyesters, polyvinyl resins, polyvinylpyrrolidone, polyesters, polycarbonates, polyamides, polyvinyl butyral, polyacrylates, cellulose esters, copolymers,and blends of these classes of resins, and others have been used with particular success.
• Natural polymeric materials such as gelatin and gum arabic may also be used.
• the resin should be able to withstand those conditions. Generally it is preferred that the polymer not decompose or lose its structural integrity at 147°C for 60 seconds and most preferred that it not decompose or lose its structural integrity at 193°C for 5 minutes.
• polymers must be compatible with the other components and solvents, in addition to having a reasonably low softening point for processability. Such polymers desirably are permeable to trapped gases.
• the selected binder must be transparent or translucent and be either clear or lightly colored. This will ensure an obvious contrast with colored areas (non-light struck) after heat development.
• the binder may serve a number of additionally important purposes in the constructions of the present invention.
• the imageable materials may be protected from ambient conditions such as moisture. The consistency of the coating and its image quality are improved. The durability of the final image is also significantly improved.
• the binder should be present as at least 25% by weight of ingredients in the layer, more preferably as at least 50% by weight and most preferably as at least 70% by weight of dry ingredients (i.e., excluding solvents in the layer).
• Dyes Leuco dyes are well known in the art. Ihese are colorless or lightly colored dyes which when subjected to an oxidation reaction form a colored dye. These leuco dyes are described in the literature (e.g., Mees and James, “The Theory of the Photographic Process", 3rd Edition, published 1966, by Macrnillan Co. (N.Y.) , see pages 283-4, 390-1; and J. Koshar, "Light-Sensitive Systems", published 1965, by Wiley and Sons, Inc. (N.Y.), see pages 367, 370-380, 406).
• leuco dyes are leuco crystal violet (LCV) and leuco malachite green (LMG) .
• LCV leuco crystal violet
• LMG leuco malachite green
• Acid or base sensitivedyes such as phenolphthalein and other indicator dyes are not useful in the present invention unless they are also oxidizable to a colored state.
• Indicator dyes would only form transient images or would be too sensitive to changes in the environment.
• the dyes which have been specifically shown to work in the present invention are discussed in detail below and include but are not limited to the following:
• the leuco dyes of the present invention become colored due to oxidation, that is, they have absorbance after coloration in the visible portion of the electromagnetic spectrum (approximately 400 to 700 nm).
• the leuco dye should be present as at least about 0.3 by weight of the binder layer, preferably at least 1% by weight, and most preferably at least 2% to 10% or more by weight of the dry weight of the imageable layer.
• temperatures should, of course, not be used during manufacture which would colorize the layer or decompose the diazonium salts. Some slight colorization is tolerable, with the initial leuco dye concentrations chosen so as to allow for anticipated colorization. It is preferred, however, that little or no leuco dye be colorized during forming or coating so that more standardized layers can be formed.
• the coating or forming temperature can be varied. Therefore, if the anticipated development temperature were, for example, 167°C, the drying temperature could be 138 °C, and it would not be desirable for the layer to gain 20% of its optical density at the drying temperature in less than 4-5 minutes.
• Such a gain would be tolerable by correspondingly increasing the amount of leuco dye.
• the preferred limitation of at least 0.2 gain in optical density or absorbance of colorless light at 132°C for 60 seconds is based on the assumption of a development temperature of 132°C.
• the 0.2 gain in optical density or absorbance should occur at that development temperature within a reasonable period of time.
• a reasonable development temperature range is between 82°C and 193°C and a reasonable dwell time is between 5 seconds and 5 minutes, preferably at between
• Diazonium Salts Light sensitive diazonium salts are well known in the art. ⁇ iese salts comprise a light sensitive aromatic nucleus with an external diazonium group and an anion associated therewith (e.g., J. Kosar, " Light-Sensitive System", published 1965, by John Wiley and Sons, Inc. (N.Y.), see pages 202-214; and P.
• X- is an anion. Any anion may be used in the diazonium salt. Anions as diverse as zinc chloride, tri-isopropyl naphthalene sulfonate, fluoroborate (i.e., BF 4 -), and bisf perfluoroalkylsulfonyl)methides may be used. Ihe change in anions may affect the speed of the imaging layer, but not its function. Any light sensitive aromatic diazonium nucleus, as known in the art, may also be used in the practice of the present invention.
• diazonium nuclei particularly those belonging to the classes pyrrolidine, morpholine, aniline, and diphenyl amine and its polymers are well known in the art and include, for example, P-anilinobenzene;. N-(4-diazo-2,4-dimethoxy phenyl) pyrrolidine; 1-diazo-2, 4-diethoxy-4-morpholino benzene; 1- diazo-4-benzoyl amino-2, 5-diethoxy benzene; 4-diazo-2,5-dibutoxy phenyl morpholino; 4- diazo-1-dimethyl aniline; 1-diazo-N,N-dimethyl aniline; 1-diazo-4-N-methyl-N-hydroxyethyl aniline; etc.
• Additives Other materials which may be useful in the formulations of the present invention include reducers and complexors, plasticizers and polyketones, stablizers, surfactants, antistatic agents, coating aids, oxidizing materials (other than nitrate ion which may be present only in amounts less than 0.1 mole nitrate to 1.0 mole dye), inhibitors, lubricants, flexibilizers, fillers and the like. All of this will be more thoroughly understood by consideration of the following examples:
• Examples 1-11 These examples examine the effect of using different binders in the formulation.
• Two separate solutions, A and B were prepared.
• .Solution A comprised .020 g phthalic acid, .010 g catechol, .10 g Phenidone A (1-phenyl-3-pyrazolidone), .200 g aromatic ketone resin, .200 g polymeric plasticizer ( ter,2,4-trimethylpentane, 1,3-diol adipate 2-ethylhexanol terminated [900-1100 molecular weight] ) and 1.060 g methyl ethyl ketone (MEK) for a total weight of 1.5 g.
• MEK methyl ethyl ketone
• Solution B comprised .051 g leuco crystal violet (4, 4 ' ,4"-methyl idynetris-(N-N dimethylaniline)), .046 g leuco malachite green ( ⁇ , p' -benzyl idenebis- (N , N-dimethylaniline) ) , and 1. 429 g tetrahydrofuran (THF), for a total weight of 1.5 g.
• leuco crystal violet (4, 4 ' ,4"-methyl idynetris-(N-N dimethylaniline)
• leuco malachite green ⁇ , p' -benzyl idenebis- (N , N-dimethylaniline)
• THF tetrahydrofuran
• Phthalic acid is useful in these formulations to stablize the coating solution by preventing the diazonium salt from reacting before development.
• Examples 12-19 These examples further investigate vinyl chloride and vinyl acetate binders.
• the reference solution 1.5 g each of solutions A and B, and 0.1 g DDMBB was prepared and mixed with the stated amount of binder (Table 2), then coated and treated as in examples 1-11. Results appear below.
• the binders of examples 12, 13 and 14 decrease progressively in molecular weight which correlates with a progressive decrease in softening points of these resins. It is of note that the ⁇ Density increases as the softening temperature of the resin decreases, reflecting better reacting conditions in softer resins.
• the binders of examples 15 and 16 are resins with acid content, a factor which did not enhance the ⁇ Density.
• Examples 20-33 The following acids and a control were screened with the resin of example 14 (VC-VA 87/13-2) using in each case 0.1g DDMBB and 4.0g of a master batch solution comprising 2.0g LCV, 18.0g toluene and a solution containing 60.0g of 40% VC-VA-87/13-2, 18% MIBK, 18% ethanol and 24% MEK:
• Example 14 The following acids and a control were screened with the resin of example 14 (VC-VA 87/13-2) using in each case 0.1g DDMBB and 4.0g of a master batch solution comprising 2.0g LCV, 18.0g toluene and a solution containing 60.0g of 40% VC-VA-87/13-2, 18% MIBK, 18% ethanol and 24% MEK:
• Example 20-33 The following acids and a control were screened with the resin of example 14 (VC-VA 87/13-2) using in each case 0.1g DDMBB and 4.0g of a master batch solution comprising 2.0
• Tetrachlorophthalic anhydride 2,4, 4- trimethylpentyl-bis (2-hydroxy-3,5-dimethylphenyl)methane (TBHDM), 2,6-bis(2'hydroxy-3'-tert butyl-5'-methyl benzyl)-4-methylphenol, and 2,2'-methylenebis(4-methyl-6-tert butylphenol) showed some degree of usefulness in increasing the ⁇ Density compared to experiments without these materials.
• Phenidone A (1-phenyl-3-pyrazolidone) and ascorbic acid greatly depressed both the Dmin and Driax values and when studied at lower levels of concentration ( .01 g) were found to be useful in depressing the Dnin.
• Examples 53-68 Small amounts of various polyketones, plasti cizers, metal salts, and benzoyl peroxide were screened for their possible effect in lowering the softening point of the resin using 4 g of a master batch solution comprising 2.0 g leuco crystal violet, 18.0 g toluene, and 60.0 g of a solution containing 40% VC-VA-87/13-2, 18% methyl isobutyl ketone, 18% ethanol, and 24% methyl ethyl ketone.
• Aromatic polyketone resin (Mohawk Industries MR-85)
• TCCI 1,1,2-trimethyl-5-carboxyl-3-(p-carboxyphenyl) indan
• TBHDM 1,1,2-trimethyl-5-carboxyl-3-(p-carboxyphenyl) indan
• Examples 128-129 Anylsis of formulations containing variable amounts of Phenidone A, phthalic acid, 1:1 DDMBB and DDBF, leuco crystal violet, TCCI, ascorbic acid, and a solution of 40% VC-VA-87/13-2 dissolved in 10% MIBK/50% MEK, in addition to solvents, was made. The best results were obtained from formulations of examples 128 and 129, shown below in Table 3.
• Formulation included .010g Ascorbic acid 2 Formulation included .050g Catechol 3 Formulation included .125g DDBF 4 Formulation included 1.000g Methanol * Resin solutin was added to diazo solution rather than LCV solution ** 1-diazo-2,5-dibutoxy-4-morpholino benzene sulfate

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• Spectroscopy & Molecular Physics (AREA)
• Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)
• Heat Sensitive Colour Forming Recording (AREA)

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• 1980
  • 1980-10-27 DE DE8181900099T patent/DE3069247D1/de not_active Expired
  • 1980-10-27 WO PCT/US1980/001444 patent/WO1981001756A1/en active IP Right Grant
  • 1980-10-27 JP JP56500300A patent/JPH0143938B2/ja not_active Expired
  • 1980-10-27 EP EP81900099A patent/EP0041984B1/en not_active Expired

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