EP0518552B1 - Wärmeempfindliches Aufzeichnungsmaterial - Google Patents

Wärmeempfindliches Aufzeichnungsmaterial Download PDF

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Publication number
EP0518552B1
EP0518552B1 EP19920305101 EP92305101A EP0518552B1 EP 0518552 B1 EP0518552 B1 EP 0518552B1 EP 19920305101 EP19920305101 EP 19920305101 EP 92305101 A EP92305101 A EP 92305101A EP 0518552 B1 EP0518552 B1 EP 0518552B1
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EP
European Patent Office
Prior art keywords
weight
recording material
thermosensitive recording
layer
water
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP19920305101
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English (en)
French (fr)
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EP0518552A1 (de
Inventor
Hiroshige Yamauchi
Hideaki Shinohara
Shuji Saito
Ken c/o Hosoya Kanazawa
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New Oji Paper Co Ltd
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New Oji Paper Co Ltd
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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
    • B41M5/41—Base layers supports or substrates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M2205/00—Printing methods or features related to printing methods; Location or type of the layers
    • B41M2205/04—Direct thermal recording [DTR]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M2205/00—Printing methods or features related to printing methods; Location or type of the layers
    • B41M2205/36—Backcoats; Back layers
    • 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 a thermosensitive recording material. More particularly, the present invention relates to a thermosensitive recording material useful for a thermosensitive plotter for outputting a drawing prepared in a computer-aided design (CAD) system, and for a thermosensitive image-printer for outputting CRT images as a hard copy in a medical measurement.
  • CAD computer-aided design
  • thermosensitive recording material comprises a substrate material, for example, a paper sheet, synthetic paper sheet or plastic resin film, and a thermosensitive colored image-forming layer formed on a surface of the substrate material and comprising, as main components, a substantially colorless dye precursor consisting of, for example, an electron-donative leuco basis dye; a color-developing agent consisting of an electron-acceptive organic acid compound, for example, a phenolic compound; and a binder, and that the colored recording images can be created on the colored image-forming layer by reacting the dye precursor with the color-developing agent upon applying heat thereto.
  • a substantially colorless dye precursor consisting of, for example, an electron-donative leuco basis dye
  • a color-developing agent consisting of an electron-acceptive organic acid compound, for example, a phenolic compound
  • thermosensitive recording material is advantageous in that the recording apparatus can be made relatively compact and small size at a low cost, and can be easily maintained, and thus is widely utilized not only as a recording medium for facsimile machines and automatic ticket-vending machines, but also as an outputting medium for various printers and plotters of colored images of POS labels, CAD images and CRT medical images.
  • EP-A-0345419 discloses a heat sensitive recording material comprising a heat sensitive recording layer and a substrate containing a synthetic resin film layer containing minute cavities, the content of the cavities in the synthetic resin film layer being 40 to 100cc/100g.
  • the heat-sensitive recording material thus produced gives a clear recorded image having a high density even with low printing energy due to high-speed printing.
  • a synthetic paper sheet having a multi-layer structure, and a bi-axially drawn thermoplastic resin film optionally containing an inorganic pigment are utilized as a recording material that must have a high water-resistance and tensile strength, or as a recording material for a printer used with a CRT medical measurement apparatus that must record colored images with a high uniformity and resolving power, or as a recording material for a CAD plotter that must record colored images with a high dimensional stability and thin line images.
  • the conventional synthetic paper sheet having the multi-layered structure is produced by heat-kneading a polyolefin resin and a white inorganic pigment, extruding a melt of the resultant mixture through a film-forming die, drawing the resultant extruded sheet in a longitudinal direction thereof, laminating, on each of the two surfaces of the drawn sheet, one or two layers each consisting of a film formed from a mixture of a polyolefin resin with a white inorganic pigment and then drawing the resultant laminated sheet in a cross direction thereof.
  • thermoplastic resin film is produced by extruding a melt of a thermoplastic resin comprising at least one member selected from, for example, polyolefin resins and polyester resins, through a film-forming die and then drawing the resultant extruded sheet biaxially, or by extruding a melt of a mixture of a thermoplastic resin with a white inorganic pigment through a film-forming die, and then drawing the resultant sheet biaxially.
  • thermosensitive recording procedure in which a thermal head is brought into contact with the recording material to record colored images at a high density, heat transmitted to a substrate material of the recording material causes the substrate material to be thermally shrunk and the recording material to be curled inward at the recorded face thereof, or to be cockled, and thus to exhibit an undesirable appearance.
  • thermosensitive recording label comprising a layer of wax or a wax-like material between the carrier sheet and the adhesive layer, opposite the thermosensitive coloring layer on the other side of the carrier sheet.
  • the wax or wax-like layer prevents the intrusion of materials such as dioctyl phthalate and dioctyl adipate into the thermosensitive coloring layer; such materials can cause discoloration of the layer, and hence illegibility of the matter printed on the backing layer.
  • An object of the present invention is to provide a thermosensitive recording material comprising a substrate sheet and a thermosensitive colored image-forming layer formed on a surface of the substrate sheet and exhibiting an excellent resistance to a creation of a curling or cockling thereof even when the substrate sheet is formed from a synthetic paper sheet having a multi-layer structure or a thermoplastic resin film.
  • thermosensitive recording material of the present invention which comprises, a substrate sheet comprising a thermoplastic resin; a thermosensitive colored image-forming layer formed on a surface of the substrate sheet and comprising a substantially colorless dye precursor, a color-developing agent reactive with the dye precursor upon heating to develop a color, and a binder; and a backcoat layer formed on an opposite surface of the substrate sheet and comprising a water-soluble polymeric material, said substrate sheet exhibiting a thermal shrinkage which in the larger of the longitudinal and cross direction values is from 1.0% to 2.0% when the sheet is heated to a temperature of 120°C, for 30 minutes, said backcoat layer having a weight of from 1 to 10 g/m2, and said water-soluble resin material being present in an amount of 20% or more based on the total weight of the backcoat layer.
  • thermosensitive recording material comprises a substrate sheet comprising a thermoplastic resin, a thermosensitive colored image-forming layer formed on a surface of the substrate sheet, a backcoat layer formed on the opposite surface of the substrate sheet, and optionally, an overcoat layer formed on the thermosensitive colored image-forming layer.
  • the substrate sheet usable for the present invention comprises at least one member selected from the group consisting of thermoplastic resin films, which may be transparent, opaque or semitransparent, and synthetic paper sheets, which are preferably opaque or semitransparent, and preferably have a thickness of 50 to 500 ⁇ m.
  • the transparent thermoplastic resin film is produced, for example, by extruding a melt of a thermoplastic resin selected from the group consisting of polyethylene, polypropylene, ethylene-vinyl acetate copolymer, polyvinyl chloride, polystyrene and polyester resins and heat-mixtures of two or more of the above-mentioned resins, through a film-forming die, and biaxially drawing the resultant extruded film.
  • a thermoplastic resin selected from the group consisting of polyethylene, polypropylene, ethylene-vinyl acetate copolymer, polyvinyl chloride, polystyrene and polyester resins and heat-mixtures of two or more of the above-mentioned resins
  • the opaque or semitransparent thermoplastic resin film can be produced from a mixture of a white inorganic pigment with the above-mentioned thermoplastic resin in the same manner as mentioned above.
  • the opaque or semitransparent synthetic paper sheet is prepared, for example, by extruding a melt of a mixture of a polyolefin resin with a white inorganic resin through a film-forming die, drawing the resultant extruded film in the longitudinal direction thereof, laminating, on the two surfaces of the drawn film, one or two films comprising a mixture of a polyolefin resin with a white inorganic pigment, and then drawing the resultant laminated sheet in the cross direction thereof.
  • the synthetic paper sheet is available under the trademark of Yupo, grades of TPG (semitransparent type), KPK (semitransparent type), WST (semitransparent type), SGG (opaque type), FPG (opaque type), GFG (opaque type), WFP (opaque and thick type), WSF (opaque type) or WCF (opaque type), from OJI YUKA GOSEISHI K.K., or under the trademark of Toyopal (opaque type) from TOYOBO K.K..
  • the substrate sheet has a thermal shrinkage restricted to a level of from 1 to 2% determined at a heating temperature of 120°C, and for a heating time of 30 minutes.
  • thermoplastic resin film or a synthetic paper sheet When a thermoplastic resin film or a synthetic paper sheet has a thermal shrinkage of 1 to 2% at a heating temperature of 120°C for 30 minutes, the film or sheet can be employed to form a substrate sheet of the thermosensitive recording material of the present invention, without applying a shrinkage-reducing treatment. If the thermal shrinkage is more than 2%, this shrinkage can be reduced to a level of 1 to 2% by heat treating the thermoplastic film or synthetic paper sheet in the form of a wound roll at a temperature of 10°C to 20°C below the softening temperature thereof for a time of one day or more. By the above-mentioned heat treatment, a residual stress of shrinkage created by the above-mentioned drawing procedure is released.
  • thermoplastic resin film or synthetic paper sheet is continuously passed through a dryer of a coater at a temperature of 60°C to 80°C for a heating time of 10 to 60 seconds.
  • the thermoplastic resin film or synthetic paper sheet must be tensed under a tension and heat-treated within a short time, and therefore, the heat-setting effect of this method is not always satisfactory. Therefore, the above-mentioned heat-treating method, in which the thermoplastic resin film or synthetic paper sheet is heat-treated in the form of a wound roll, is advantageous in that the shrinkage-reducing effect is satisfactory and the heat treatment cost is low.
  • the thermal shrinkage of the substrate sheet is determined in the following manner.
  • a substrate sheet is cut to provide a specimen having a length of 200 mm in the longitudinal or cross direction of the substrate sheet and a width of 15 mm in the cross or longitudinal direction of the substrate sheet.
  • the specimen is placed in a heating oven without restriction, heated at a temperature of 120°C for 30 minutes, and then cooled to room temperature.
  • the required thermal shrinkage of the specimen is in the larger of the values measured in the longitudinal and cross directions.
  • thermosensitive recording material of the present invention a specific backcoat layer must be formed on a surface of a substrate sheet opposite to the surface thereof on which a thermosensitive colored image-forming layer is formed.
  • the backcoat layer comprises at least 20% by weight of a water-soluble polymeric material, and optionally comprises, in addition to the water-soluble polymeric material, a water-insoluble polymeric material employed in the form of an aqueous emulsion or dispersion, and an additive selected from cross-linking agents, pigments and antistatic agents.
  • the cross-linking agents are used to enhance the water-resistance of the backcoat layer.
  • the pigments effectively prevent an undesirable blocking phenomenon of the backcoat layer.
  • the antistatic agents comprise at least one member selected from anionic and cationic electrolytic polymeric materials that effectively prevent an undesirable static electrification of the backcoat layer.
  • the backcoat layer has a weight of 1 to 10 g/m2, and is formed by applying a coating liquid containing the above-mentioned materials to the opposite surface of the substrate sheet and drying the coating liquid layer. When dried, the coated liquid layer creates a strong shrinking force that causes the resultant thermosensitive recording material to be curled inwardly on the backcoat layer side.
  • thermosensitive colored image-forming layer when a thermosensitive colored image-forming layer is formed on a front surface of the substrate sheet, a shrinking force is created in the resultant layer, to thus cause the resultant thermosensitive recording sheet to be curled inwardly on the thermosensitive colored image-forming layer side.
  • thermosensitive recording material When the curling force created in the thermosensitive colored image-forming layer is balanced by the curling force created in the backcoat layer, the resultant thermosensitive recording material is released from the undesirable curling or cockling phenomenon.
  • the resultant backcoat layer cannot satisfactorily prevent the curling or cockling phenomenon of the resultant thermosensitive recording material.
  • the resultant thick backcoat layer hinders the coating and drying operations.
  • the backcoat layer comprises at least 20% by weight of a water-soluble polymeric material comprising, for example, at least one member selected from the group consisting of polyvinyl alcohol resins, starch, modified starches, gum arabic, gelatin, casein, chitosan, methyl cellulose, hydroxy-ethyl cellulose, hydroxymethyl cellulose, polyvinyl pyrrolidone, polyacrylic acid salts, polyacrylamides, styrene-maleic anhydride copolymers, methylvinylether-maleic anhydride copolymers and isoprene-maleic anhydride copolymers, which have a satisfactory film-forming property.
  • a water-soluble polymeric material comprising, for example, at least one member selected from the group consisting of polyvinyl alcohol resins, starch, modified starches, gum arabic, gelatin, casein, chitosan, methyl cellulose, hydroxy-ethyl cellulose, hydroxymethyl cellulose, polyvinyl
  • the water-soluble polymeric material is optionally employed together with a water-insoluble polymeric material comprising at least one member selected from the group consisting of, for example, vinyl acetate-acrylic acid ester copolymers, polyurethane resins, polyvinyl chloride resins, polyvinylidene chloride resins, methacrylic acid ester copolymers and acrylic acid ester copolymers usually employed in the form of an aqueous emulsion or dispersion, and exhibit a satisfactory film-forming property and a lowest film-forming temperature of 20°C or less.
  • the water-insoluble polymeric material is used in an amount of 0 to 70%, preferably 10% to 60%, based on the total dry weight of the backcoat layer.
  • a cross-linking agent is preferably added in an amount of 1% to 10% based on the weight of the backcoat layer.
  • the cross-linking agent preferably comprises at least one member selected from the group consisting of dialdehyde compounds, for example, glyoxal and paraformaldehyde; polyamine compounds, for example, polyethyleneimine; epoxide compounds; polyamide compounds; melamine-formaldehyde resins; diglycidyl compounds, for example, glycerol diglycidylether; dimethylolurea compounds; aziridine compounds; block isocyanate compounds and cross-linking inorganic compounds, for example, ammonium persulfate, ferric chloride and magnesium chloride, usually, the cross-linking agent is employed in an amount of 0 to 20%, preferably 1% to 10%, based on the total dry weight of the backcoat layer.
  • dialdehyde compounds for example, glyoxal and paraformaldehyde
  • polyamine compounds for example, polyethyleneimine
  • epoxide compounds polyamide compounds
  • melamine-formaldehyde resins
  • the backcoat layer optionally comprises a pigment preferably having an average particle size of 5 ⁇ m or less, more preferably from 10 nm to 2,000 nm.
  • the pigment comprises at least one member selected from the group consisting of inorganic pigments, for example, calcium carbonate, magnesium carbonate, kaolin, clay, talc, anhydrous clay, silica, diatomaceous earth, synthetic aluminum silicate, zinc oxide, titanium dioxide, aluminum hydroxide, barium sulfate, and surface-coated or treated calcium carbonate and silica, and organic pigments, for example, urea-formaldehyde resins, styrene-methacrylic acid copolymer resins and polystyrene resins.
  • the pigment is contained in an amount of 0 to 60%, preferably 10% to 50%, based on the total dry weight of the backcoat layer.
  • the antistatic agent comprises at least one member selected from, for example, alkali metal and ammonium salts of polystyrenesulfonic acid and polyacrylic acid.
  • the backcoat layer is formed by coating a coating liquid containing the above-mentioned materials on the opposite (back) surface of the substrate sheet by a customary coating method, for example, an air knife, mayer bar, blade, reverse roll or slit die coating method.
  • a customary coating method for example, an air knife, mayer bar, blade, reverse roll or slit die coating method.
  • thermosensitive recording material of the present invention a thermosensitive colored image-forming layer is formed on the front surface of the substrate sheet by the customary coating method as mentioned above.
  • the surface of the thermosensitive colored image-forming layer is treated by a super calender, gloss calender or a machine calender, to smoothen the surface and to enhance the color density and sensitivity of the colored images.
  • the thermosensitive colored image-forming layer preferably has a weight of 3 to 10 g/m2, and comprises a substantially colorless dye precursor, a color-developing agent reactive with the dye precursor upon heating to develop a color, and a binder.
  • the substantially colorless dye precursor comprises at least one electron-donative color-forming compound, for example, fluoran compound selected from 2,2-bis ⁇ 4-[6'-(N-cyclohexyl-N-methylamino)-3'-methylspiro(phthalide-3,9'-xanthene)-2'-ilamide]phenyl ⁇ propan, 3-diethylamino-6-methyl-7-anilinofluoran, 3-pyperidino-6-methyl-7-anilinofluoran, 3-(N-methyl-N-cyclohexylamino)-6-methyl-7-anilinofluoran, 3-diethylamino-7-chloroanilinofluoran, 3-[N-ethyl-N-(p-methylphenyl)amino]-6-methyl-7-anilinofluoran, 3-diethylamino-7-(methatrifluoromethyl)anilinofluoran, 3-[N-ethyl-N-tetrahydr
  • the color-developing agent comprises at least one electron-acceptive organic acid compound capable of being gasified or liquefied at room temperature or more, preferably upon heating at a temperature of 70°C or more, and of reacting with the dye precursor upon heating to develop a color.
  • the color-developing agent usable for the present invention preferably comprises at least one member selected from phenolic compounds, for example, 4,4'-isopropylidene diphenol (bisphenol A), 4,4'-isopropylidene-bis(2-chlorophenol), 4,4'-isopropylidene-bis(2-methylphenol), 4,4'-isopropylidene-bis(2,6-di-tert-butylphenol), 4,4'-sec-butylidene diphenol, 4,4'-cyclohexylidene diphenol, 4-tert-butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, 4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 3,3'-dihydroxydiphenylsulfone, 3,3'-diamino-4,4'-dihydroxydiphenylsulfone, 3,3'-diallyl-4,4'-dihydroxydip
  • the color-developing agent in the heat-sensitive color-forming layer is present in an amount of 1 to 5 parts by weight, preferably 1.5 to 3 parts by weight, per part by weight of the dye precursor.
  • the binder in the heat-sensitive color-forming layer comprises at least one polymeric material selected from the same water-soluble polymeric materials and water-insoluble polymeric materials as those usable for the backcoat layer, unless when mixed with aqueous dispersions of the dye precursor and of the developing agent the binder causes the resultant mixture to be colored, to be coagulated or to exhibit an increased viscosity. Also, preferably the binder effectively enhances the mechanical strength of the resultant thermosensitive colored image-forming layer, and does not cause an undesirable reduction of the thermosensitivity of the thermosensitive colored image-forming layer and an increase in the sticking property of the thermosensitive colored image-forming layer to the thermal head.
  • thermosensitive colored image-forming layer optionally contains the same cross-linking agent as that used for the backcoat layer, to improve the water-resistance thereof.
  • thermosensitive colored image-forming layer optionally comprises at least one additive selected from, for example, customary white pigments, dispersing agents, antifoaming agents, fluorescent dyes and thermofusible substances.
  • the white pigment can be selected from the same inorganic and organic pigments as those usable for the backcoat layer, and is preferably used in an amount of 10 to 50% based on the total dry weight of the thermosensitive colored image-forming layer.
  • the dispersing agent, antifoaming agent and fluorescent dye can be selected from those usable for the conventional thermosensitive colored image-forming layer, and are used in a customary amount.
  • the thermofusible substance preferably has a melting point of from 80°C to 110°C and is selected from fatty acid amide, for example, stearic acid amide, stearic acid ethylene-bisamide, oleic amide, palmitic amide, coconut fatty acid amide, behenic amide; wax (or lubricant) materials, for example, calcium stearate, polyethylene waxes, carnauba wax, paraffin waxes, ester waxes; aromatic carboxylic esters, for example, dimethyl terephthalate ester, dibutyl terephthalate ester, dibenzyl terephthalate ester, dibutyl isophthalate ester, and phenyl 1-hydroxy-naphthoate ester; 1,2-di(3-methylphenoxy)ethane, 1,2-diphenoxy-ethane, 1-phenoxy-2-(4-methylphenoxy)ethane, diphenyl carbonate, p-benzyl biphenyl
  • thermofusible substance is preferably employed in an amount of 4 parts by weight or less per part by weight of the color-developing agent.
  • the coating liquid optionally contains a wetting agent, for example, acetylene glycol or a dialkylsulfosuccinic acid salt.
  • the thermosensitive colored image-forming layer is optionally coated with an overcoat layer comprising 20% to 60% by weight of a pigment, 39% to 79% by weight of a binder resin, 1% to 10% by weight of a cross-linking agent and 0 to 40% by weight of a lubricant.
  • the overcoat layer has a weight of 1.0 to 5.0 g/m2, more preferably 2.0 to 4.0 g/m2. If the amount of the overcoat layer is less than 1.0 g/m2, the resultant overcoat layer sometimes has an unsatisfactory uniformity and includes pinholes and coating defects.
  • the pinholes and coating defects will allow an oily or fatty substance or plasticizer to penetrate the thermosensitive colored image-forming layer therethrough, and thus the resistance of the resultant formed in the thermosensitive colored image-forming layer colored image to the oily or fatty substance or plasticizer is reduced.
  • the amount is more than 5 g/m2
  • the resultant overcoat layer causes a decrease in thermosensitivity of the thermosensitive colored image-forming layer and a reduction in color density of the resultant colored images.
  • the binder resin and the pigment are present in a weight ratio of 80 : 20 to 40 : 60. If the weight ratio is more than 80 : 20, sometimes the resultant overcoat layer exhibits an undesirably increased stickiness, which results in a sticking of the recording sheets to a thermal head of a printer during a printing operation, and has an undesirably lowered bonding property to a printing ink in a labelling operation. If the weight ratio is less than 40 : 60, the resultant overcoat layer sometimes exhibits an unsatisfactory barrier effect against the oily or fatty substance or plasticizer, and thus the resultant colored images have a lower persistency.
  • the pigment, binder resin, cross-linking agent and lubricant for the overcoat layer can be selected from those usable for the above-mentioned backcoat layer. Also, the overcoat layer can be formed in the same manner as that for the backcoat layer, as mentioned above.
  • the binder resin in the overcoat layer preferably comprises 10% to 100% by weight, more preferably 20% to 90% by weight,of a water-soluble polymeric material and 0 to 90% of weight, more preferably 10% to 80% by weight, of a water-insoluble polymeric material.
  • the water-soluble and -insoluble polymeric materials can be selected from those used for the backcoat layer.
  • the heat treated synthetic paper sheet exhibited a thermal shrinkage of 1.0 to 2.0% at 120°C in the longitudinal and cross directions thereof as shown in Table 1.
  • An aqueous dye precursor dispersion (A) was prepared in the following composition. Component Part by weight 3-(N-methyl-N-cyclohexylamino) -6-methyl-7-anilinofluoran 5 10% aqueous solution of a methylvinylether-maleic anhydride copolymer 5 Water 8 The composition was disperse-pulverized in an ultraviscomill until the average size of the pulverised particles became 1 ⁇ m or less.
  • An aqueous color developing agent dispersion (B) was prepared in the following composition.
  • Component Part by weight 2 4-dihydroxy-diphenylsulfone 30 10% aqueous solution of a methylvinylether-maleic anhydride copolymer 30 Water 22
  • the composition was dispersed and pulverized in an ultraviscomill until the average size of the pulverized particles became 1 ⁇ m or less.
  • a coating liquid was prepared by mixing 30 parts by weight of the aqueous dye precursor dispersion A and 90 parts by weight of the aqueous color developing agent dispersion with 45 parts by weight of a 60% aqueous calcium carbonate slurry, 40 parts by weight of a 10% aqueous polyvinyl alcohol solution, 32 parts by weight of a styrene-butadiene rubber (SBR) latex (solid content: 50% by weight) and 70 parts by weight of water.
  • SBR styrene-butadiene rubber
  • thermosensitive colored image-forming layer (2) Formation of a thermosensitive colored image-forming layer.
  • thermosensitive colored image-forming layer having a dry weight of 5.5 g/m2.
  • a coating liquid for an overcoat layer was prepared in the following composition.
  • Component Part by weight Kaolinite clay aqueous slurry (Solid content: 60% by weight) 40 Modified polyvinyl alcohol aqueous solution (Solid content: 10% by weight) 300
  • Casein aqueous solution (Solid content: 10% by weight) 200
  • Zinc stearate aqueous dispersion (Solid content: 30% by weight) 13
  • Dimethylol urea aqueous solution Solid content: 30% by weight) 15 Water 300
  • the coating liquid was applied onto the surface of the thermosensitive colored image-forming layer, to form an overcoat layer with a dry weight of 3.0 g/m2.
  • a coating liquid for a backcoat layer was prepared in the following composition.
  • Component Part by weight Casein aqueous solution (Solid content: 10% by weight) 200 Oxidized starch aqueous solution (Solid content: 10% by weight) 200 Calcium carbonate aqueous slurry (Solid content: 70% by weight) 79 Dimethylol urea aqueous solution (Solid content: 30% by weight) 15 Water 6
  • the coating liquid was applied onto the opposite surface of the substrate sheet, to form a backcoat layer having a dry weight of 3.0 g/m2.
  • the overcoat layer surface of the resultant recording sheet was calendered by a super calender to an extent such that the calendered surface exhibited a Bekk smoothness of 1,000 seconds to 1,200 seconds as indicated in Table 1, measured by an Ohken type smoothness tester (J. TAPPI, No. 6).
  • thermosensitive recording sheet was cut into A-4 size sheets, and the sheets were subjected to a thermal printing operation in a checkered pattern having dimensions of 1 cm ⁇ 1 cm, using a customary thermal printer.
  • the printed sheet was observed by the naked eye to evaluate a resistance of the recording sheet to cockling, and a degree of curling of the recording sheet was determined in the following manner.
  • the printed sheet was placed on a horizontal plane and height of apices of four corners of the sheet from the horizontal plane were measured.
  • the degree of curling of the printed sheet was represented by an average value of the measured heights in mm.
  • thermosensitive recording sheet was prepared and tested by the same procedures as in Example 1 with the following exceptions.
  • the substrate sheet was heat-treated under the conditions as shown in Table 1 and the resultant heat-treated substrate sheet exhibited the thermal shrinkages as shown in Table 1.
  • the coating liquid for the backcoat layer had the following composition.
  • Component Part by weight Oxidized starch aqueous solution (Solid content: 10% by weight) 350 SBR latex (Solid content: 50% by weight) 30 Kaolinite clay aqueous slurry (Solid content: 60% by weight) 83 Water 37
  • the coating liquid was applied onto the opposite surface of the substrate sheet to form a backcoat layer with a dry weight of 2.0 g/m2 in Example 4, 4.5 g/m2 in Example 5, and 7.0 g/m2 in Example 6.
  • thermosensitive recording sheet was prepared and tested by the same procedures as in Example 1, with the following exceptions.
  • the substrate sheet was prepared by heat treating a thermoplastic resin film in the form of a wound roll, available under the trademark of Toyopal from Toyobo K.K.. having a thickness of 50 ⁇ m and a thermal shrinkage of 3.5% in the longitudinal direction thereof at 120°C and comprising a polyethylene resin, at a temperature of 100°C for 24 hours.
  • the resultant heat treated film exhibited the thermal shrinkages as shown in Table 1.
  • Example 7 the same coating liquid for the backcoat layer as in Example 1 was applied onto the opposite surface of the substrate sheet, to form a back layer having a weight of 3.0 g/m2.
  • Example 8 the same back layer-coating liquid as in Example 4 was applied in the same manner as in Example 7.
  • thermosensitive recording sheet was prepared and tested in the same manner as in Example 1, except that the substrate sheet consisting of the synthetic paper sheet Yupo FPG-80 was not heat-treated.
  • thermosensitive recording sheet was prepared and tested in the same manner as in Example 7, except that the substrate sheet consisting of the thermoplastic film Toyopal was not heat-treated.
  • thermosensitive recording sheet was produced and tested by the same procedures as in Example 7, except that the backcoat layer was formed in a small weight of 0.5 g/m2.
  • Table 1 clearly shows that the recording sheets of Examples 1 to 8 in accordance with the present invention exhibited a satisfactory resistance to cockling and curling in a thermal printing procedure, whereas the comparative recording sheets of Comparative Examples 1 to 3 were significantly cockled and curled by the thermal printing procedure.

Landscapes

  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Heat Sensitive Colour Forming Recording (AREA)
  • Thermal Transfer Or Thermal Recording In General (AREA)

Claims (14)

  1. Wärmeempfindliches Aufnahmematerial, umfassend:
    ein Substratblatt, welches ein thermoplastisches Harz umfaßt;
    eine wärmeempfindliche Farbbild-bildende Schicht, welche auf einer Oberfläche des Substratblattes ausgebildet ist und einen im wesentlichen farblosen Farbstoffvorläufer, ein farbentwickelndes Mittel, welches beim Erwärmen mit dem Farbstoffvorläufer unter Entwicklung einer Farbe reagiert, und ein Bindemittel umfaßt; und
    eine Rückseitenüberzugsschicht, welche auf der gegenüberliegenden Oberfläche des Substratblattes ausgebildet ist und ein wasserlösliches Polymermaterial umfaßt,
    wobei das Substratblatt eine thermische Schrumpfung aufweist, welche über den längeren der longitudinalen und quergerichteten Werte 1,0% bis 2,0% beträgt, wenn das Blatt auf eine Temperatur von 120°C während 30 Minuten erwärmt wird,
    die Rückseitenüberzugsschicht ein Gewicht von 1 bis 10 g/m² besitzt, und
    das wasserlösliche Harzmaterial in einer Menge von 20% oder mehr, bezogen auf das Gesamtgewicht der Rückseitenüberzugsschicht, vorhanden ist.
  2. Wärmeempfindliches Aufnahmematerial nach Anspruch 1, worin das Substratblatt mindestens ein aus der aus thermoplastischen Harzfolien und synthetischen Papierblättern bestehenden Gruppe ausgewähltes Element umfaßt.
  3. Wärmeempfindliches Aufnahmematerial nach Anspruch 2, worin die thermoplastischen Harzfolien aus der aus Polyethylen, Polypropylen, Ethylen-Vinylacetat-Copolymer, Polyvinylchlorid, Polystyrol und Polyesterharzfolien bestehenden Gruppe ausgewählt sind.
  4. Wärmeempfindliches Aufnahmematerial nach Anspruch 2, worin die synthetischen Papierblätter eine Vielschichtstruktur besitzen.
  5. Wärmeempfindliches Aufnahmematerial nach irgendeinem vorangehenden Anspruch, worin das Substratblatt eine Dicke von 50 bis 500 µm besitzt.
  6. Wärmeempfindliches Aufnahmematerial nach irgendeinem vorangehenden Anspruch, worin die Rückseitenüberzugsschicht ein Bindemittelharz umfaßt, welches zu 20 bis 100 Gew.-% aus einem wasserlöslichen Polymermaterial und zu 0 bis 80 Gew.-% aus einem wasserunlöslichen Polymermaterial besteht.
  7. Wärmeempfindliches Aufnahmematerial nach Anspruch 6, worin das wasserlösliche Polymermaterial mindestens ein aus der aus Polyvinylalkoholharzen, Stärke, modifizierte Stärken, Gummiarabikum, Gelatine, Casein, Chitosan, Methylcellulose, Hydroxyethylcellulose, Hydroxymethylcellulose, Polyvinylpyrrolidon, Polyacrylsäuresalzen, Polyacrylamiden, Styrol-Maleinsäureanhydrid-Copolymeren, Methylvinylether-Maleinsäureanhydrid-Copolymeren und Isopren-Maleinsäureanhydrid-Copolymeren bestehenden Gruppe ausgewähltes Element umfaßt.
  8. Wärmeempfindliches Aufnahmematerial nach Anspruch 6, worin das wasserunlösliche Polymermaterial mindestens ein aus der aus Vinylacetat-Acrylsäureester-Copolymeren, Polyurethanharzen, Polyvinylchloridharzen, Polyvinylidenchloridharzen, Methacrylsäureester-Copolymeren und Acrylsäureester-Copolymeren bestehenden Gruppe ausgewähltes Element umfaßt, welche in der Form einer wäßrigen Emulsion oder Dispersion vorliegen.
  9. Wärmeempfindliches Aufnahmematerial nach irgendeinem vorangehenden Anspruch, worin das wasserlösliche Polymermaterial in der Rückseitenüberzugsschicht mit einem Vernetzungsmittel quervernetzt ist, welches mindestens ein aus der aus Dialdehydverbindungen, Polyaminverbindungen, Epoxyverbindungen, Polyamidharzen, Melaminformaldehydharzen, Diglycidylverbindungen, Dimethylolharnstoffverbindungen, Aziridinverbindungen, Blockisocyanatverbindungen, Ammoniumpersulfat, Eisen(III)-chlorid und Magnesiumchlorid bestehenden Gruppe ausgewähltes Element umfaßt, wobei das Vernetzungsmittel in einer Menge von 1% bis 10%, bezogen auf das Gewicht der Rückseitenüberzugsschicht, vorhanden ist.
  10. Wärmeempfindliches Aufnahmematerial nach irgendeinem vorangehenden Anspruch, worin die Rückseitenüberzugsschicht ferner mindestens ein Additiv umfaßt, welches aus der aus Pigmenten und Antistatikmitteln bestehenden Gruppe ausgewählt ist.
  11. Wärmeempfindliches Aufnahmematerial nach irgendeinem vorangehenden Anspruch, welches ferner eine auf der wärmeempfindlichen Farbbild-bildenden Schicht ausgebildete Überzugsschicht umfaßt und 20 bis 60 Gew.-% eines Pigments, 40 bis 80 Gew.-% eines Bindemittelharzes, 0,5 bis 10 Gew.-% eines Vernetzungsmittels und 0 bis 39,5% eines Gleitmittels umfaßt.
  12. Wärmeempfindliches Aufnahmematerial nach Anspruch 11, worin die Überzugsschicht ein Gewicht von 1,0 bis 5,0 g/m² besitzt.
  13. Wärmeempfindliches Aufnahmematerial nach Anspruch 11 oder Anspruch 12, worin das Bindemittelharz und das Pigment in der Überzugsschicht in einem Gewichtsverhältnis von 80 : 20 bis 40 : 60 vorhanden sind.
  14. Wärmeempfindliches Aufnahmematerial nach irgendeinem der Ansprüche 11 bis 13, worin das Bindemittelharz in der Überzugsschicht 50 bis 100 Gew.-% eines wasserlöslichen Polymermaterials und 0 bis 50 Gew.-% eines wasserunlöslichen Polymermaterials umfaßt.
EP19920305101 1991-06-12 1992-06-03 Wärmeempfindliches Aufzeichnungsmaterial Expired - Lifetime EP0518552B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP3166155A JPH04364983A (ja) 1991-06-12 1991-06-12 感熱記録体
JP166155/91 1991-06-12

Publications (2)

Publication Number Publication Date
EP0518552A1 EP0518552A1 (de) 1992-12-16
EP0518552B1 true EP0518552B1 (de) 1996-03-06

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Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19542598A1 (de) * 1995-11-15 1997-05-22 Feldmuehle Ag Stora Wärmeempfindlicher Aufzeichnungsbogen
DE19713590C1 (de) * 1997-04-02 1998-10-29 Stora Publication Paper Ag Wärmeempfindlicher Aufzeichnungsbogen
WO1999014056A1 (de) 1997-09-12 1999-03-25 Stora Spezialpapiere Gmbh Wärmeempfindlicher aufzeichnungsbogen mit einer rückseitenbeschichtung, die stärke, ein acrylatcopolymer und einen alkalischen katalysator enthält
DE19740072A1 (de) * 1997-09-12 1999-03-18 Stora Spezialpapiere Gmbh Wärmeempfindlicher Aufzeichnungsbogen
DE19748258A1 (de) * 1997-10-31 1999-05-06 Stora Spezialpapiere Gmbh Wärmeempfindlicher Aufzeichnungsbogen
JP2001056522A (ja) 1999-08-20 2001-02-27 Fuji Photo Film Co Ltd 熱現像画像記録材料
DE10014351A1 (de) 2000-03-24 2001-09-27 Mitsubishi Hitec Paper Flensbu Aufzeichnungspapier zum rückseitigen Bedrucken
EP2329958B1 (de) * 2009-12-01 2012-10-03 Mitsubishi HiTec Paper Europe GmbH Wärmeempfindliches Aufzeichnungsmaterial mit Rückseitenbeschichtung

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS57146686A (en) * 1981-03-05 1982-09-10 Ricoh Co Ltd Thermal recording type label sheet
US4370370A (en) * 1981-06-08 1983-01-25 Ricoh Company, Ltd. Thermosensitive recording adhesive label
US4996182A (en) * 1988-06-08 1991-02-26 Toyo Boseki Kabushiki Kaisha Heat-sensitive recording material
JPH0822627B2 (ja) * 1988-08-31 1996-03-06 ダイアホイルヘキスト株式会社 プリンター用転写材

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DE69208741D1 (de) 1996-04-11
DE69208741T2 (de) 1996-08-22
JPH04364983A (ja) 1992-12-17
EP0518552A1 (de) 1992-12-16

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