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
  • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
  • B41M5/337—Additives; Binders
  • B41M5/3375—Non-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
  • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
  • B41M5/333—Colour developing components therefor, e.g. acidic compounds
  • B41M5/3333—Non-macromolecular compounds

Definitions

• the present invention relates to heat-sensitive recording paper. More particularly, it relates to heat-­sensitive recording paper that has not only high sensitivity but also sufficient resistance to water to experience only limited fading of image even if it is submerged in water.
• heat-sensitive recording paper finds use in a broad range of applications including measuring recorders, terminal printers such as word processors, facsimiles, automatic ticket venders and bar code labels. As these recording apparatus have become versatile in applications and their performance improved, the requirements to be satisfied by heat-sensitive recording paper have become strict.
• a protective layer be provided by coating the surface of a heat-sensitive color-forming layer on ordinary paper with an aqueous emulsion of a resin having a film-­forming capability and resistance to chemicals (Japanese Patent Public Disclosure No. 54-128347) or a water-soluble high-molecular weight compound such as polyvinyl alcohol (Japanese Utility Model Public Disclosure No. 56-125354). These methods are capable of preventing the color formation in non-image areas or fading in image areas even if the heat-sensitive recording paper is placed in contact with overwrap films or exposed to oils.
• An object, therefore, of the present invention is to provide heat-sensitive recording paper that is capable of producing a record of high sensitivity, that will resist fading of image areas even if it is submerged in water, and that will experience only limited fogging in the white background.
• Common leuco dyes may be used in the heat-sensitive color-forming layer of the heat-sensitive recording paper of the present invention.
• fluoran-based leuco dyes which may be exemplified by the following: 3-diethylamino-6-methyl-7-anilinofluoran; 3-(N-ethyl-p-toluidino)-6-methyl-7-anilinofluoran; 3-(N-cyclohexyl-N-methylamino)-6-methyl-7-anilinofluoran; 3-diethylamino-7-(ortho-chloroanilino)fluoran; 3-diethylamino-7-(meta-trifluoromethylanilino)fluoran; 3-diethylamino-6-methyl-7-(ortho,para-­dimethylanilino)fluoran; 3-pyrrolidino-6-methyl-7-anilinofluoran; 3-piperidino-6-methyl-7-anilinofluor
• Parabenzylbiphenyl which is the other essential component of the heat-sensitive color-forming layer works as an accelerator of color formation. Presumably, it will cause a melting point dropping effect when present in combi­nation with the organic acidic substance and react with the leuco dye at a temperature that is lower than the melting point of either compound. Further, the incorporation of this parabenzylbiphenyl will contribute to the accomplish­ment of a higher sensitivity and a higher degree of white­ness in the background.
• the 4,4′-thiobis(6-t-butyl-3-methylphenol) and para­benzylbiphenyl are generally used with the leuco dye in such amounts that 0.5 - 10 parts by weight of 4,4′-thiobis(6-t-­butyl-3-methylphenyl) and 0.2 - 10 parts by weight of parabenzylbiphenyl are combined with one part by weight of the leuco dye.
• Organic or inorganic pigments commonly employed in coating and other applications may be used as fillers in the heat-sensitive recording paper of the present invention.
• Typical examples include calcium carbonate, clay, calcined clay, aluminum hydroxide, talc, magnesium carbonate, silica, polystyrene particles and a urea-formaldehyde resin powder.
• Suitable binders may be selected from among the following: water-soluble resins such as various polyvinyl alcohols, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, styrene-acrylic copolymer, isobutylene-maleic acid copolymer and starches; and aqueous emulsions of styrene-butadiene copolymer, vinyl acetate copolymers, ethylene-vinyl acetate copolymer, etc.
• binders of high water resistance are selected and these may be used in combination with either themselves or crosslinking agents.
• Various waxes may also be incorporated in order to provide greater ease in coating operations.
• Supports that can be used in the present invention may be selected from among paper, plastic films, synthetic paper, and any other suitable materials.
• the heat-sensitive recording paper of the present invention may be provided with conventional protective layers that are effective in preventing color formation in non-image areas or fading in image areas due to contact with packaging films or exposure to oils.
• protective layers may be made of film-forming water-soluble resins or chemical resistant aqueous emulsions.
• lubricants and crosslinking agents may also be used for the purpose of antiblocking or increasing the strength of water-resistant films having good slip properties.
• Solutions A - D were prepared by pulverizing compositions having the recipes shown below with a sand grinder until an average particle size of 1.0 ⁇ m was attained.
• Solution A 3-dibutylamino-6-methyl-7-anilinofluoran 200 parts Polyvinyl alcohol (10% aq.
• Solution A 100 parts by weight
• Solution B 400 parts by weight
• a styrene-butadiene copolymer latex 50% solids; 500 parts by weight
• a zinc stearate emulsion 20% solids; 625 parts by weight
• This solution was applied onto fine paper (basis weight, 50 g/m2) in a dry coating weight of 5 g/m2 and dried to prepare heat-­sensitive recording paper.
• Heat-sensitive recording paper was prepared as in Example 1 except that the heat-sensitive color-forming layer was coated with a protective layer that was formed from a coating solution having the recipe shown below and which was deposited in a dry weight of 3.0 g/m2.
• Coating Solution for Protective Layer Polyvinyl alcohol (10% aq. sol.) (polymerization degree, 1100; saponification degree, 98.5%) 100 parts Calcined clay (Ansilex 93, Engelhard Corp.) 6 parts 20% zinc stearate emulsion 2 parts Glyoxal (40% aq. sol.) 1 part
• Solution A 100 parts by weight
• Solution C 400 parts by weight
• a styrene-butadiene copolymer latex 50% solids; 500 parts by weight
• a zinc stearate emulsion 20% solids; 625 parts by weight
• This solution was applied onto fine paper (basis weight, 50 g/m2) in a dry coating weight of 5 g/m2 and dried to prepare heat-­sensitive recording paper.
• Heat-sensitive recording paper was prepared as in Comparative Example 1 except that the heat-sensitive color-­forming layer was coated with a protective layer that was formed from a coating solution having the recipe shown below and which was deposited in a dry weight of 3.0 g/m2.
• Coating Solution for Protective Layer Polyvinyl alcohol (10% aq. sol.) (polymerization degree, 1100; saponification degree, 98.5%) 100 parts Calcined clay (Ansilex 93, Engelhard Corp.) 6 parts 20% zinc stearate emulsion 2 parts Glyoxal (40% aq. sol.) 1 part
• Solution A 100 parts by weight
• Solution D 400 parts by weight
• a styrene-butadiene copolymer latex 50% solids; 500 parts by weight
• a zinc stearate emulsion 20% solids; 625 parts by weight
• This solution was applied onto fine paper (basis weight, 50 g/m2) in a dry coating weight of 5 g/m2 and dried to prepare heat-­sensitive recording paper.
• Heat-sensitive recording paper was prepared as in Comparative Example 3 except that the heat-sensitive color-­forming layer was coated with a protective layer that was formed from a coating solution having the recipe shown in Comparative Example 2 and which was deposited in a dry weight of 3.0 g/m2.
• the heat-sensitive recording paper was submerged in tap water (40°C) for 24 hours, recovered, dried with air and subjected to measurements of the densities in image and non-­image areas with a Macbeth reflection densitometer (RD 514).
• Example Comparative Example 1 2 1 2 3 4 Water resistance of recorded area Before testing 1.33 1.30 1.02 1.00 1.05 1.04 After testing 1.30 1.28 0.14 0.18 0.72 0.75 Color retention 97% 98% 14% 18% 69% 72% Water resistance of white background Before testing 0.09 0.10 0.11 0.11 0.25 0.29 After testing 0.10 0.10 0.11 0.12 0.30 0.32 Degree of whiteness 82% 78% 75% 70% 65% 60% Sensitivity for color formation 1.33 1.30 1.02 1.00 1.05 1.04
• the above data show that the present invention enables the preparation of a heat-sensitive recording material that has good balance between various aspects such as whiteness, sensitivity for color formation and water resistance in both image and non-image areas.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Heat Sensitive Colour Forming Recording (AREA)

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Publications (2)

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Cited By (3)

Citations (4)

• 1988
  • 1988-12-07 JP JP63309150A patent/JPH02155687A/ja active Pending
• 1989
  • 1989-12-04 EP EP19890312602 patent/EP0372878A3/de not_active Withdrawn

Patent Citations (4)

Non-Patent Citations (3)

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