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
  • G03C1/002—Photosensitive materials containing microcapsules
• • 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
  • G03C1/54—Diazonium salts or diazo anhydrides

Definitions

• This invention relates to a heat-sensitive recording material and, more particularly, to a diazo type heat-sensitive recording material capable of being fixed by light. Still more particularly, it pertains to a light-fixable heat-sensitive recording material providing a high color density and, upon fixing, forming a white background by light exposure only in a lower exposure amount.
• an excellent heat-sensitive recording material has been obtained by a technique of microencapsulating at least one of the components relating to the color-forming reaction as a core substance by forming a wall around the core substance through polymerization (Japanese Patent Application (OPI) No. 190886/84).
• This recording material can truly give high coloration density, can show good stability, and can be fixed by light. In practical use, however, when a diazonium salt is used in an amount to give a sufficient coloration density, a long time is required for fixing by light. Thus, in apparatus containing a heat-recording zone and a light-fixing zone, the recording material requires that the speed of conveying be slowed down or that several fixing lamps be used in a wide fixing zone which has caused serious problems with respect to increasing recording speed and reducing size of the apparatus, as are currently required.
• fixing means both that a diazonium salt, one of the color-forming components, is decomposed by light and becomes unable to form color any more even when heated and that a diazonium salt which often appears yellow loses this yellow color when exposed to light to form a white non-printed background (or to become colorless). From a practical viewpoint, the latter is often of importance because the yellow color residue gives an unfavorable yellowish appearance to users, and paper coming out of a recording machine is therefore required to be white in non-printed areas. On the other hand, even when a non-reacted diazonium salt remains in a small amount, it practically causes no problems since it will soon be naturally decomposed, during being handled, by light from lighting fixtures or by natural light.
• Another object of the present invention is to provide a heat-sensitive recording material which can be fixed by photo decomposition of a non-reacted diazo compound after heat recording.
• a further object of the present invention is to provide a light-fixing type heat-sensitive recording material which provides high coloration sensitivity and coloration density and gives a white background when fixed by light exposure in a small exposure amount.
• a light-fixable heat-sensitive recording material comprising a diazonium salt component and a coupler capable of reacting with the diazonium salt component to form color
• the diazonium salt component comprises at least two diazonium salts, one having a maximum light absorption wavelength of 410 ⁇ 10 nm and the other having a maximum light absorption wavelength of 385 ⁇ 10 nm.
• the diazonium salts to be used in the present invention are in the form of diazo compounds represented by the general formula ArN2 ⁇ X ⁇ (wherein Ar represents an aromatic moiety, N2 ⁇ represents a diazonium group, and X ⁇ represents an acid anion). These compounds have varying maximum light absorption wavelengths (hereinafter referred to as " ⁇ max ”) depending upon the position and the kind of substituents in the Ar moiety.
• ⁇ max maximum light absorption wavelengths
• the present invention is characterized in that there is used said combination of at least two of a diazonium salt having a ⁇ max of 410 ⁇ 10 nm and a diazonium salt having a ⁇ max of 385 ⁇ 10 nm among the above-describd diazo compounds.
• Their structure is not particularly limited as long as the above-described requirements are satisfied.
• diazonium salt having a ⁇ max of 410 ⁇ 10 nm examples include 2,5-dibutoxy-4-morpholino­benzenediazonium hexafluorophosphate, 2,5-dibutoxy-4-­morpholinobenzenediazonium tetrafluoroborate, 2,5-­dibutoxy-4-morpholinobenzenediazonium chloride-zinc chloride, 2,5-dibutoxy-4- ⁇ N-(2-ethylhexanoyl)piperadino ⁇ ­benzenediazonium hexafluorophosphate, 2-5-diethoxy-4-[N-­ ⁇ 2-(2,4-di-tert-amylphenoxy)butyryl ⁇ -piperadino]­benzenediazonium 1,5-naphthalenedisulfonate, 3-(2-­ethylthioethoxy)-4-pyrodinobenzenediazonium tetraphenylborate, 3-(2-octyloxye
• diazonium salt having a ⁇ max of 385 ⁇ 10 nm examples include 4-[N- ⁇ 2-(2,4-di-tert-amyl­phenoxy)butyryl ⁇ piperadino]benzenediazonium hexa­ fluorophosphate, 4-dioctylaminobenzenediazonium tetraphenylborate, 4- ⁇ N-(2-ethylhexanoyl)­piperadino ⁇ benzenediazonium 1,5-naphthalene-disulfonate, 4-dihexylamino-2-hexyloxybenzenediazonium hexafluoro­phosphate, 4-N-ethyl-N-hexadecylamino-2-ethoxy-benzo­diazonium hexafluorophosphate, 3-chloro-4-dioctylamino-2-­octyloxybenzenediazonium hexafluorophosphate.
• diazonium salts are also characterized in that they can undergo coupling reactions with the following couplers to form colors with various hues of from short wavelength to long wavelength depending upon the kind of coupler. Black coloration, which is popularly favored, can easily be attained by a suitable combination with the coupler.
• the coupling components (couplers) to be used in the present invention are those which couple with a diazo compound (diazonium salt) in a basic environment to form a dye.
• a diazo compound diazonium salt
• Specific examples thereof include resorcin, phloroglucin, sodium 2,3-dihydroxynaphthalene-6-sulfonate, 1-hydroxy-2-naphthoic acid morpholinopropylamide, 1,5-­dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,3-­dihydroxy-6-sulfanylnaphthalene, 2-hydroxy-3-naphthoic acid morpholinopropylamide, 2-hydroxy-3-naphthoic acid anilide, 2-hydroxy-3-naphthoic acid-2 ⁇ -methylanilide, 2-­hydroxy-3-naphthoic acid ethanolamide, 2-hydroxy-3-­ naphthoic acid octy
• the amount of the coupling component is preferably 0.1 to 10 parts by weight per part by weight of the diazonium salt component.
• the amount of the diazonium salt component used in the present invention is preferably 0.05 to 5.0 g/m2.
• a basic substance for accelerating coloration may preferably be included.
• the basic substance sparingly water-soluble or water-insoluble basic substances and those substances which generate alkali when heated may be used.
• the basic substances include nitrogen-containing compounds such as inorganic and organic ammonium salts, organic amines, thiazoles, pyrimidines, piperazines, guanidines, imidazoles, imidazolines, triazoles, morpholines, piperidines, amidines, formamidines, pyridines, etc.
• nitrogen-containing compounds such as inorganic and organic ammonium salts, organic amines, thiazoles, pyrimidines, piperazines, guanidines, imidazoles, imidazolines, triazoles, morpholines, piperidines, amidines, formamidines, pyridines, etc.
• ammonium acetate tricyclohexylamine, tribenzylamine, octadecylbenzylamine, stearylamine, 2-benzylimidazole, 4-phenylimidazole, 2-­phenyl-4-methyl-imidazole, 2-undecylimidazoline, 2,4,5-­trifuryl-2-imidazoline, 1,2-diphenyl-4,4-dimethyl-2-­imidazoline, 2-phenyl-2-imidazoline, 1,2,3-triphenyl­quanidine, 1,2-ditolylguanidine, 1,2-dicyclo­hexylguanidine, 1,2,3-tricyclohexylguanidine, guanidine trichloroacetic acid salt, N,N ⁇ -dibenzylpiperadine, 4,4 ⁇ - dithiomorpholine, morpholinium trichloroacetate, 2-amino­benzothiazole, 2-benzoylimidazo
• the heat-sensitive recording material of the present invention may be obtained by finely dispersing two or more of the above-described diazonium salts, couplers, and preferably basic substances, and, if necessary sensitizing agents and other additives in a binder.
• at least one of the above-­described substances is preferably microencapsulated in a manner described in the foregoing Japanese Patent Application (OPI) No. 65043/83.
• the microcapsules are not of the type used in conventional recording materials which type are ruptured by heat or pressure to permit the reactive substance contained in the core of the microcapsules to come into contact with a reactive substance outside of the microcapsules and cause a coloration reaction, but are the type which, when reactive substances existing in the core of the microcapsules and outside of them are heated, permit them to permeate through the microcapsule wall and undergo reaction therebetween.
• a process of dissolving or dispersing a reactive substance to be retained in the core substance of the microcapsules in a water-insoluble or sparingly water-soluble organic solvent and, after emulsifying the solution or dispersion, forming a microcapsule wall around the droplets is particularly preferable.
• This process is disclosed in U.S. Patents 3,726,804, 3,796,669, 3,281,383, 3,773,675 and 3,793,­268.
• Microencapsulation of at least one of the color-­forming components is markedly effective for improving shelf stability.
• a diazonium salt or a coupler is effective.
• two or more diazonium salts may be microencapsulated in different capsules or in the same capsule.
• the use of a sensitizing agent is preferably in veiw of sensitivity.
• sensitizing agents those which are described in Japanese Patent Applications (OPI) No. 201986/85, 40190/86 and 84283/86, may favorably be used.
• the sensitizing agent is preferably used in the present invention in an amount of 0.1 to 20 parts by weight per part by weight of the diazonium salt component.
• the ratio of diazonium salt having a ⁇ max of 410 ⁇ 10 nm to that having a ⁇ max of 385 ⁇ 10 nm to be used is suitably 9/1 to 1/9 by weight.
• the ratio may properly be decided in view of the kind of coupler to be used, hue of formed color, coloration density and fixing speed.
• the heat-­sensitive recording material of the present invention may contain fine powder of pigments such as silica, barium sulfate, titanium oxide, aluminum hydroxide, zinc oxide, or calcium carbonate, or of styrene beads or urea-melamine resin.
• metal soaps may be used for preventing sticking.
• coating may be conducted by using a proper binder.
• binder various emulsions of polyvinyl alcohol, methylcellulose, carboxymethylcellulose, hydroxypropylcellulose, gum arabic, gelatin, polyvinylpyrrolidone, casein, styrene-butadiene latex, acrylonitrile-butadiene latex, polyvinyl acetate, a polyacrylic acid ester or an ethylene-vinyl acetate copolymer may be used.
• citric acid, tartaric acid, oxalic acid, boric acid, phosphoric acid, or pyrophosphoric acid may be added as acid stabilizers in addition to the above-described ingredients.
• the heat-sensitive recording material of the present invention can be obtained by preparing a coating solution containing a diazo compound, a coupling component, and other additives, coating the solution on a support such as paper or synthetic resin film according to a bar-coating process, a blade-coating process, an air knife-coating process, a gravure-coating process, a roll-­coating process, a spray-coating process or dip-coating process, and then drying the coating.
• the heat-sensitive recording material of the present invention may have an overcoat layer on the heat-­ sensitive layer for the purpose of preventing sticking or imparting water resistance, and may have a backing layer on the back side of the support for the purpose of preventing curling and generation of static charge, and for improving running properties, and resistance to water and oil.
• the heat-sensitive recording material of the present invention may be used as paper for printers such as a facsimile machine, a CRT, a bar code printer, etc. which require high-speed recording. After heat-recording, the heat-sensitive recording material can be fixed by exposure to thereby decompose unreacted diazo compound.
• the recording material is characterized in that it provides high coloration density and a white background even when high-speed printing is conducted.
• the recording material of the present invention may also be used as so-called heat-developable copying material which is to be thermally developed after photo recording.
• a sample prepared by coating this capsule solution A had a ⁇ max of 408 nm.
• Capsule solution B was obtained in the same manner as capsule solution A except for changing the amount of diazonium salt to 5.3 parts.
• the resulting sample had a ⁇ max of 408 nm.
• Capsule solution C was obtained in the same manner as capsule solution B except for changing the diazonium salt to a diazonium salt having the following structure: and excluding trimethylolpropane trimethacrylate.
• a sample obtained by coating this solution and drying the coat had a ⁇ max of 387 nm.
• Capsule solution D was obtained in the same manner as capsule solution A except for changing the diazonium salt in the diazonium capsule solution B to the following:
• the resulting mixture was dispersed for 24 hours in a sand mill to obtain a black color-forming dispersion of 1.5 ⁇ m in average particle size.
• the visual density of the thus formed image-­recorded areas was measured using a Macbeth densitometer.
• the yellow density of the background areas was also measured in the same manner.
• the hue of each of the resulting images was observed with the naked eye.
• Comparative examples 1 and 2 show that to raise the image density by using a diazonium salt having a ⁇ max of long wavelength causes an extreme increase in background yellowing. Comparative examples 1 and 3 show that a diazonium salt having a ⁇ max of short wavelength fails to give black coloration, although high image density is obtained with less background yellowing.
• Examples 1, 2, 3 and 4 show that the combined use of the two kinds of diazonium salts according to the present invention gives recording materials providing high image density, undergoing less background yellowing, and forming a clear black image.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Heat Sensitive Colour Forming Recording (AREA)
• Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)

Applications Claiming Priority (2)

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Cited By (3)

Citations (4)

• 1987
  • 1987-03-27 JP JP62073192A patent/JPH0679867B2/ja not_active Expired - Fee Related
• 1988
  • 1988-03-24 EP EP88302579A patent/EP0284378A3/de not_active Withdrawn

Patent Citations (4)

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