Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/40—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used characterised by the base backcoat, intermediate, or covering layers, e.g. for thermal transfer dye-donor or dye-receiver sheets; Heat, radiation filtering or absorbing means or layers; combined with other image registration layers or compositions; Special originals for reproduction by thermography
  • B41M5/42—Intermediate, backcoat, or covering layers
  • B41M5/44—Intermediate, backcoat, or covering layers characterised by the macromolecular compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/40—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used characterised by the base backcoat, intermediate, or covering layers, e.g. for thermal transfer dye-donor or dye-receiver sheets; Heat, radiation filtering or absorbing means or layers; combined with other image registration layers or compositions; Special originals for reproduction by thermography
  • B41M5/42—Intermediate, backcoat, or covering layers
  • B41M5/426—Intermediate, backcoat, or covering layers characterised by inorganic compounds, e.g. metals, metal salts, metal complexes

Definitions

• the present invention relates to thermo­sensitive recording materials having excellent thermal response and having minimized tailings or foreign matters adhered to a thermal head.
• Thermosensitive recording materials are generally composed of a support having provided thereon a thermosensitive recording layer containing as major constituents an ordinarily colorless or slightly colored electron giving dye precursor and an electron receptive developer. Upon being heated by means of a thermal head, thermal pen or laser beam, the dye precursor instan­taneously reacts with the developer to form a recorded image, as disclosed in Japanese Patent KOKOKU (Post Exam. Publication) Nos. 43-4160, 45-14039, etc. Because of the advantages of relatively simple design of devices, easy maintenance and making no noise, the recording devices employing such thermosensitive recording materials are being used in a wide field including recording instruments for measurements, facsimiles, printers, terminal devices for computers, labels, and automatic vending machines for railroad tickets and the like.
• thermosensitive recording materials On the other hand, a dot density of thermal head was generally 8 lines/mm but has recently become a density as high as 16 lines/mm. In addition, a dot area has become small and, demands for printing small-sized characters in high image quality or printing characters with density gradation by Dither method have been increasing. Thus, good printability, namely, to obtain images faithfully reproduced from dots on a head has been much more demanded than ever.
• undercoat layer As described above, by the provision of undercoat layer, the higher density recording has been progressed than before. However, demands for much higher sensitivity and more improvement in the dot repro­ducibility in recent years cannot be coped simply with the provision of undercoat layer merely aiming at smoothening the surface.
• An object of the present invention is to provide thermosensitive recording materials having good thermal response and good dot reproducibility in response to requirements for higher sensitivity and improving dot reproducibility which could not be solved by the foregoing techniques as described above.
• the arrangement of the present invention is characterized in that aggregated high polymer particles are coated as an undercoat layer interposed between a support and a thermosensitive coating layer.
• the aggregated high polymer particles coated as the undercoat layer is considered to exhibit the effect of more effectively applying thermal energy to the thermosensitive layer by preventing the thermal energy from a thermal head from escaping to the outside of a system due to the thermally insu­lating property of porous particles as well as the effect to provide a smoother surface by smoothing the irregularities of the support like an undercoat layer to which only a pigment is coated. Further, it is considered that the elasticity of the porous particle layer improves the close contact property of the surface of a thermo­sensitive paper to the thermal head and exhibits an excellent dot reproducibility.
• porous particles used in the present invention have an outside diameter of 5 ⁇ m or less, preferably have an outside diameter of 2 ⁇ m or less and most preferably have an outside diameter of 1 ⁇ m or less.
• the porous particles having an outside diameter greater than 5 ⁇ m are used, the thermosensitive recording layer having an excellent thermal response, which is an object of the present invention, cannot be provided.
• aggregated high polymer particles can be provided by aggregating fine particles of a high polymer material to particles of the high polymer material emulsified to a diameter of about 0.05 ⁇ m - 0.5 ⁇ m serving as a core in a poly­merizing process so that they have a diameter of 1 ⁇ m - 5 ⁇ m, the aggregated high polymer particles having an oil absorbing property of 50 - 200 ml/100 g and a specific surface area (BET) of 5 - 20 m2/g.
• BET specific surface area
• These aggregated high polymer particles can provide a thermosensitive recording material which is particularly excellent in a thermal response when styrene-acryl copolymer resin is used.
• a typical example thereof is XMRP-170 made by Mitsui Toatsu Co., Ltd. or the like.
• Conventional styrene-acrylic copolymer particles are not porous and they cannot provide a sufficient effect of improving a thermal response because they are not porous.
• the first layer described above it is also possible to incorporate other pigments in such an amount that does not interfere with the effect of aggregated high polymer particles.
• a pigment ordinarily used for coated paper, etc., e.g., an organic pigment such as polyethylene, polystyrene, ethylene-vinyl acetate, urea-formaldehyde resin, etc.; diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, etc. They may be used singly or as admixture of two or more.
• An amount of the pigment described above to be used in combination is not particularly limited but preferably less than 50 wt% of the amount of the first layer.
• thermosensitive recording layer is directly provided on the aggregated high polymer particle layer
• a color forming component melted by thermal energy from a thermal head is absorbed into the hollow particle layer and colored images are shielded, sometimes resulting in rather decreasing image density or adherence of foreign matters onto the thermal head or sticking upon printing.
• the provision of the oil-absorbing inorganic pigment layer further onto the porous particle layer as the second undercoat layer would not only prevent those defects but also act to render the surface smoother which was already smoothened by providing the first undercoat layer.
• pigments generally used for coated paper, etc. can be used and are exempli­fied by calcium carbonate, kaolin, calcined kaolin, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, silicon oxide, etc.
• the pigments showing an oil absorbing amount of 70 ml/100 g or more, especially calcined kaolin and silicon oxide are preferred ones.
• the porous particles as the first layer in the present invention are effective when they are coated in a coverage of 1 g/m2 or more.
• the porous particles are coated in an excessively large amount, properties as paper are rather injured than improving that of thermosensitive.
• the base paper is thinned to make its whole thickness even. This would result in a problem of flexural rigidity.
• a coverage of 3 to 15 g/m2 is thus preferred.
• a coverage of 1 to 10 g/m2 of oil-absorbing inorganic pigment of the second layer is most preferred. Where a coverage in the second layer is large, the thermal transfer becomes poor so that the heat insu­lating properties and elasticity of the first layer are not sufficiently utilizable in some occasion.
• thermosensitive layer By providing a thermosensitive layer on the thus provided undercoat layer, desired properties can be obtained.
• Dye precursors used in the present invention are not particularly limited so long as they are generally used for pressure-sensitive recording paper or thermosensitive recording paper. Specific examples include the following dye precursors.
• thermosensitive paper As dye developers used in the present invention, electron accepting compounds generally employed for thermosensitive paper are used; in particular, phenol derivatives, aromatic carboxylic acid derivatives or metal compounds thereof, N,N′-diarylthiourea derivatives, etc. are used. Among them, particularly preferred ones are phenol derivatives.
• p-phenyl­phenol p-hydroxyacetophenone
• 4-hydroxy-4′-methyl­diphenylsulfone 4-hydroxy-4′-isopropoxydiphenylsulfone
• 4-hydroxy-4′-benzenesulfonyloxydiphenylsulfone 1,1-­bis(p-hydroxyphenyl)propane, 1,1-bis(p-hydroxyphenyl)­pentane, 1,1-bis(p-hydroxyphenyl)hexane, 1,1-bis(p-­hydroxyphenyl)cyclohexane, 2,2-bis(p-hydroxyphenyl)­propane, 2,2-bis(p-hydroxyphenyl)butane, 2,2-bis(p-­hydroxyphenyl)hexane, 1,1-bis(p-hydroxyphenyl)-2-­ethylhexane, 2,2-bis(3-chloro-4-hydroxyphenyl)propane, 1,1-bis(p-hydroxyphenyl)
• thermosensitive layer may also contain as pigments diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, urea-formalin resin, etc.; may further contain waxes such as N-hydroxymethylstearic amide, stearic amide, palmitic amide, etc.; naphthol derivatives such as 2-benzyloxynaphthalene, etc.; biphenyl derivatives such as p-benzylbiphenyl, 4-­allyloxybiphenyl, etc.; polyether compounds such as 1,2-bis(3-methylphenoxy)ethane, 2,2′-bis(4-methoxy­phenoxy)diethyl ether, bis(4-methoxyphenyl)ether, etc.; carbonate or oxalate diester derivatives such as diphenyl carbonate, dibenzyl oxalate, di(p-fluorobenz
• higher fatty acid metal salts such as zinc stearate, calcium stearate, etc.
• waxes such as paraffin, oxidized paraffin, polyethylene, oxidized polyethylene, stearic amide, castor wax, etc.
• dispersing agents such as sodium dioctylsulfosuccinate, etc.
• adhesives used for the first undercoat layer, second undercoat layer and thermosensitive recording layer used in the present invention various adhesives generally used are usable.
• the adhesives include water soluble adhesives such as starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, sodium polyacrylate, acrylic amide/acrylate copolymer, acryl­amide/acrylate/methacrylate ternary copolymer, alkali salts of styrene/maleic anhydride copolymer, alkali salts of ethylene/maleic anhydride copolymer, etc.; latexes such as polyvinyl acetate, polyurethane, polyacrylates, styrene/butadiene copolymer, acrylonitrile/­butadiene copolymer, methyl acrylate/butadiene copolymer, ethylene/vinyl acetate
• a mixture having the following composition was stirred to prepare a coating liquid for the first layer.
• XMRP-100 porous particle emulsion composed of styrene-acryl copolymer resin made by Mitsui Toatsu Kagaku K.K.; particle diameter: about 1.0 ⁇ m, solid content: 40%
• Styrene-Butadiene copolymer latex 50% aqueous dispersion
• thermosensitive suspension was prepared in the following formulation, using the prepared [Suspension C] and [Suspension D].
• thermosensitive recording material a thermosensitive recording material weighing 40 g/m2 in the following coverages with a Mayor bar to prepare a thermosensitive recording material.
• thermosensitive layer was prepared in a manner similar to Example 1 except that a coating liquid for the first layer was prepared by stirring a mixture having the following composition and coated in a coverage of 8 g/m2.
• MXRP-140 porous particle emulsion composed of styrene-acryl copolymer resin made by Mitsui Toatsu Kagaku K.K.; particle diameter: about 0.5 ⁇ m, solid content: 40%
• Styrene-Butadiene copolymer latex 50% aqueous dispersion
• thermosensitive recording material was prepared in a manner similar to Example 1 except that a coating liquid for the first layer was prepared by stirring a mixture having the following composition and coated in a coverage of 8 g/m2.
• XMRP-170 porous particle emulsion composed of styrene-acryl copolymer resin made by Mitsui Toatsu Kagaku K.K.; particle diameter: about 0.9 ⁇ m, solid content: 40%
• Styrene-Butadiene copolymer latex 50% aqueous dispersion
• thermosensitive recording material was prepared in such a manner that the coating liquid for the first layer used in Example 1 was coated in a coverage of 8 g/m2, no coating was effected to the second layer and the thermosensitive suspension was directly coated like Example 1.
• thermosensitive recording material was prepared in a manner similar to Example 1 except that 100 parts of Ultra White-90 (kaolin for the purpose of coating, made by Engelhardt Co., Ltd.) were used in place of 100 parts of ANSILEX in the preparation of Suspension B (coating liquid for the second layer) used in Example 1.
• Ultra White-90 kaolin for the purpose of coating, made by Engelhardt Co., Ltd.
• thermosensitive recording material for the comparative study was prepared by directly coating the thermosensitive coating liquid prepared in Example 1 in a coverage of 5.5 g/m2 without coating the coating liquids for the first and second layers prepared in Example 1.
• thermosensitive recording material for the comparative study was prepared by directly coating the coating liquid for the second layer prepared in Example 1 on a base paper in a coverage of 8 g/m2 and then coating the thermosensitive suspension prepared in Example 1 in a coverage of 5.5 g/m2 thereon without coating the coating liquid for the first layer prepared in Example 1.
• thermosensitive recording material for the comparative study was prepared by directly coating the coating liquid for the second layer prepared in Example 1 on a base paper in a coverage of 11 g/m2 and then coating the thermosensitive suspension prepared in Example 1 to the amount of 5.5 g/m2 thereon without coating the coating liquid for the first layer prepared in Example 1.
• thermosensitive recording material was prepared in a manner similar to Example 1 except that a coating liquid for the first layer was prepared by stirring a mixture having the following composition and coated in a coverage of 8 g/m2.
• Spherical particle emulsion composed of styrene-acryl copolymer resin (particle diameter: about 1.0 ⁇ m, solid content: 40%) 100 parts Styrene-Butadiene copolymer latex (50% aqueous dispersion) 10 parts Water 20 parts
• thermosensitive recording material was prepared by directly coating the thermosensitive suspension after coating the coating liquid for the first layer in a coverage of 8 g/m2 without coating the second layer.
• thermosensitive recording materials prepared as described above were treated by a super­calendering so as to have compiled with a Beck's degree of smoothness varied between 400 and 500 seconds. And these materials were compared with respect to recording density, printability and degree of adhering tailings or foreign matters using a FIII facsimile test machine.
• the test machine was (TH-PMD) manufactured by Okura Denki Co., Ltd. Printing was performed using with a thermal head showing its dot density of 8 dots/mm and its head resistance of 185 ohm at a head voltage of 15 V, for its load time of 0.10 ms and 0.12 ms.
• the recording density was measured with Macbeth RD-918 reflection densitometer.
• Table 1 sensitivity printability tailings 0.10 ms 0.12 ms
• Example 1 0.86 1.22 ⁇ ⁇ 2 0.86 1.23 ⁇ ⁇ 3 0.95 1.29 ⁇ ⁇ 4 0.77 1.10 ⁇ ⁇ ⁇ ⁇ ⁇ 5 0.80 1.14 ⁇ ⁇ ⁇ ⁇ Comparative Example 1 0.34 0.57 X X 2 0.56 0.97 ⁇ ⁇ 3 0.61 1.01 ⁇ ⁇ 4 0.70 1.09 ⁇ ⁇ 5 0.58 0.95 ⁇ ⁇ ⁇ good ⁇ ⁇ ⁇ relatively good ⁇ no good X bad

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• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Heat Sensitive Colour Forming Recording (AREA)

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• 1988
  • 1988-09-29 JP JP63246752A patent/JP2755396B2/ja not_active Expired - Lifetime
• 1989
  • 1989-09-29 DE DE1989627698 patent/DE68927698T2/de not_active Expired - Lifetime
  • 1989-09-29 EP EP89118033A patent/EP0361500B1/fr not_active Expired - Lifetime

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