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
  • B41M5/333—Colour developing components therefor, e.g. acidic compounds
  • B41M5/3333—Non-macromolecular compounds

Definitions

• the present invention relates to a thermosensitive recording material on which colored images are formed by heating. More particularly, the present invention relates to a thermosensitive recording material capable of forming thereon colored images having a high persistency for a record storage thereof for a long time.
• thermosensitive record material is able to record thereon colored images exhibiting an excellent resistance to moisture, heat, oily and fatty substances, and plasticizers, and thus has a superior stability when storaged for a long time, and has a high whiteness, and therefore is useful as colored image-recording sheets, sheets for use in facsimiles and cash dispensers, as passenger tickets, commuter's passes, labels such as POS labels, cards such as prepaid cards, and as transit passes.
• thermosensitive recording material comprises a supporting substrate, 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 supporting substrate and comprising an electron-donative dye precursor, for example, a leuco basic dye, an electron-acceptive color-developing agent consisting of an organic acid substance, for example, a phenol compound, and a binder.
• an electron-donative dye precursor for example, a leuco basic dye
• an electron-acceptive color-developing agent consisting of an organic acid substance, for example, a phenol compound
• thermosensitive recording material is disclosed in Japanese Examined Patent Publication Nos. 43-4,160, 45-14,039 and 48-27,736, and is widely employed in practice.
• thermosensitive recording material is advantageous in that colored images can be easily formed only by heating, and the recording apparatus can be made relatively compact and small size, at a low cost, and is easily maintained, and thus is useful as an information-recording material for various outputs or printers used with, for example, computers, facsimile machines, automatic ticket-vending machines, scientific measurement recorders, and CRT medical measurement recorders.
• thermosensitive colored image-forming layer comprises a conventional color-developing agent together with the dye precursor and the binder
• the reaction of the dye precursor with the color-developing agent is reversible, and thus the resultant colored images fade with a lapse of time.
• This fading of the colored images is accelerated by exposure to light, high temperatures and high humidity, and promoted by contact with an oily or fatty substance or a plasticizer, and the colored images fade to an extent such that the faded images cannot be recognized.
• thermosensitive colored image-forming layer containing a phenolic antioxidant.
• Japanese Unexamined Patent Publication No. 56-146,796 discloses a protective layer formed from a hydrophobic polymeric compound emulsion on a thermosensitive colored image-forming layer.
• Japanese Unexamined Patent Publication No. 58-199,189 discloses an intermediate layer formed from a water-soluble polymeric compound solution or a hydrophobic polymeric compound emulsion on a thermosensitive colored image-forming layer, and a surface layer formed from a solution of a hydrophobic polymer in a solvent on the intermediate layer.
• thermosensitive colored image-forming layer containing an additive consisting of an epoxy compound and/or an aziridine compound.
• thermosensitive colored image-forming layer containing the phenolic antioxidant In the thermosensitive colored image-forming layer containing the phenolic antioxidant, the resultant colored images exhibit a longer persistency in the ambient atmosphere than that of a conventional colored image-forming layer free from the phenolic antioxidant, but the improvement in the storage stability of the resultant colored images is still not satisfactory. Also, the phenolic antioxidant does not effectively enhance the resistance of the colored images to the oily or fatty substances and plasticizes.
• the resistance of the colored images to oily or fatty substance or plasticizer is determined in such a manner that an oily or fatty substance, for example, a salad oil, or a plasticizer, is brought into contact with colored images, the colored images are left in contact with the oily or fatty substance or the plasticizer for a predetermined time, and then a retention of the color density of the tested colored images is measured in comparison with an initial color density thereof.
• an oily or fatty substance for example, a salad oil, or a plasticizer
• the resultant colored images exhibit an enhanced storage stability in the ambient atmosphere, to a certain extent, but the fading of the colored images cannot be avoided after a lapse of a long time.
• the resistance of the colored images to the oily or fatty substances, or to the plasticizer, immediately after the contact with the oily or fatty substance, or the pasticizer is improved, the colored images gradually fade with a lapse of time and a penetration of the oily or fatty substance, or the plasticizer, into the colored image-forming layer, and finally disappear. Therefore, the provision of the protecting layer or the intermediate and surface layer cannot completely eliminate this undesirable color-fading of the images.
• the additon of the epoxy compound and/or aziridine compound to the colored image-forming layer is unsatisfactory in that it takes a long time to satisfactorily stabilize the colored images formed on the colored image-forming layer by a heat-recording operation, and therefore, if an oily or fatty substance, for example, salad oil, is brought into contact with the colored image-forming layer immediately after the heat-recording operation, the resultant colored images are faded to a great extent.
• the resultant thermosensitive colored image-forming layer exhibits a lowered whiteness, and sometimes, is color-developed at a relatively low temperature of 50°C to 60°C which is lower than the temperature at which a heat recording operation is carried out.
• This phenomenon is referred to as a low temperature ground color-developing phenomenon hereafter.
• An object of the present invention is to provide a thermosensitive recording material allowing colored images having an excellent storage persistency over a long time and a superior resistance to oil or fat substance, plasticizer, heat, and moisture, to be formed thereon.
• Another object of the present invention is to provide a thermosensitive recording material having a satisfactory whiteness, thermosensitivity, and inhibition of a low temperature ground color-developing phenomenon.
• Still another object of the present invention is to provide a thermosensitive recording material useful for facsimile printers, word processer printers, video printers, CRT image-forming recording material, medical diagnosis, passenger's tickets, coupon tickets, and commuter's passes, which must have a high persistency in terms of the quality of the colored images recorded thereon, and for label sheets in a POS bar code price-indicating system, to be attached to an inside surface of a polyvinyl chloride film containing a pasticizing agent and wrapping fresh food or meat containing an oily or fatty substance, which label sheets are unavoidably brought into contact with the plasticizing agent and/or the oily or fatty substance.
• thermosensitive recording material of the present invention which comprises a sheet substrate, and a thermosensitive colored image-forming layer formed on a surface of the sheet substrate and comprising a substantially colorless dye precursor, a color developing agent reactive with the dye precursor upon heating to thereby develop a color, and a binder, the color developing agent comprising at least one aromatic sulfonyl (thio) amide compound selected from the group consisting of the compounds of the formulae (I) and (II): and in which formulae (I) and (II), X and Y, respectively and independently from each other, represent a member selected from the group consisting of oxygen and sulfur atoms;
• R1 represents a member selected from the group consisting of unsubstituted aromatic mono-and poly-cyclic groups, and substituted phenyl groups having at least one substituent selected from the group consisting of lower alkyl groups, aryl groups and halogen atoms;
• R2 represents a member selected from the group consist
• thermosensitive colored image-forming layer further contains a colored image-stabilizing agent comprising at least one member selected from the group consisting of aromatic compounds having at least one epoxy group and organic compounds, namely, aromatic, aliphatic and cycloaliphatic compounds, having at least one aziridinyl group.
• a colored image-stabilizing agent comprising at least one member selected from the group consisting of aromatic compounds having at least one epoxy group and organic compounds, namely, aromatic, aliphatic and cycloaliphatic compounds, having at least one aziridinyl group.
• thermosensitive recording material of the present invention comprises a sheet substrate and a thermosensitive colored image-forming layer formed on a surface of the sheet substrate.
• thermosensitive colored image-forming layer comprises a substantially colorless dye precursor, a color-developing agent reactive with the dye precursor upon heating, to thereby develop a color, and a binder.
• the color developing agent must comprise at least one aromatic sulfonyl(thio)amide compound selected from N-arylsulfonyl(thio)carbamic acid esters the formula (I): and N-arylcarbonylarylsulfonamides and N-alkylcarbonylarylsulfonamides of the formula (II):
• X and Y respectively and independently from each other, represent a member selected from the group consisting of oxygen and sulfur atoms;
• R1 represents a member selected from the group consisting of unsubstituted aromatic mono-and poly-cyclic groups, and substituted phenyl groups having at least one substituent selected from the group consisting of lower alkyl groups, aryl groups and halogen atoms;
• R2 represents a member selected from the group consisting of substituted alkyl groups having at least one substituent selected from the group consisting of aralykyl and aryloxy groups, unsubstituted aromatic mono- and polycyclic groups, and substituted aromatic mono- and polycyclic groups having at least one substituent selected from the group consisting of alkyl, alkenyl, aryl, aralkyl, alkyloxy, aryloxy, aralkyloxy, alkylmercapto, arylmercapto, aralkylmercapto, alkyloxycarbonyl
• R1 is as defined above, and R3 represents a member selected from the group consisting of substituted phenyl groups having at least one substituent selected from the group consisting of lower alkyl groups, aryl groups and halogen atoms, unsubstituted aromatic mono- and poly-cyclic groups and aliphatic and cycloaliphatic hydrocarbon groups having 1 to 20 carbon atoms.
• the aliphatic and cycloaliphatic hydrocarbon groups may be saturated or unsaturated.
• the cycloaliphatic hydrocarbon groups have 3 to 20 carbon atoms.
• aromatic sulfonyl(thio)amide compounds of the formulae (I) and (II) do not have an acid group, for example, a phenolic hydroxyl group or carboxyl group, nevertheless those aromatic sulfonyl(thio)amide compounds serve as a color-developing agent for the electron-donative dye-precursor in the thermosensitive colored image-forming layer.
• the N-arylsulfonyl(thio) carbamic acid esters of the formula (I) are preferably selected from: phenyl N-(p-toluenesulfonyl) carbamate (m.p.: 106°C) 2,3,4-trimethylphenyl N-(p-toluenesulfonyl) carbamate (m.p.: 144°C), benzyl N-(p-toluenesulfonyl) carbamate (m.p.: 98°C), 2-phenoxyethyl N-(p-toluenesulfonyl) carbamate (m.p.: 120°C), p-cumylphenyl N-(p-toluenesulfonyl) carbamate (m.p.: 120°C), o-biphenyl N-(p-toluenesufonyl) carbamate (m.p.:
• N-arylcarbonylarylsulfonamides and N-alkylcarbonylarylsulfonamides of the formula(II) are preferably selected from: N-benzoylbenzenesulfonamide (m.p.: 147°C), N-(o-toluoyl) benzenesulfonamide (m.p.: 91°C), N-(m-toluoyl) benzenesulfonamide (m.p.: 116°C), N-(p-toluoyl) benzenesulfonamide (m.p.: 135°C), N-(1-naphthoyl) benzenesulfonamide (m.p.: 174°C), N-(2-naphthoyl) benzenesulfonamide (m.p.: 151°C), N-benzoyl-o-toluenesulfonamide (m.p
• thermosensitive colored image-forming layer contains a colored image-stabilizing agent comprising at least one member selected from aromatic compounds having at least one epoxy group of the formula: as disclosed in Japanese Unexamined Patent Publication Nos. 62-164,579, and 2-220,885 and organic compounds having at least one aziridinyl group of the formula:
• the aromatic compounds having at least one epoxy group and usable for the present invention are preferably selected from the group consisting of 4,4′-bis(2 ⁇ ,3 ⁇ -epoxypropyloxy)diphenylsulfone, 2,2-bis[4′-(2 ⁇ ,3 ⁇ -epoxypropyloxy)phenyl]propane, 1,4-bis(2′,3′-epoxypropyloxy)benzene, 4-(2 ⁇ -methyl-2 ⁇ ,3 ⁇ -epoxypropyloxy)-4′-benzyloxy-diphenylsulfone, 4-(2 ⁇ -3 ⁇ -epoxypropyloxy)-4′-(p-methylbenzyloxy)-diphenylsulfone, epoxidized o-novolak cresol resines, 4,4′-bis(2 ⁇ ,3 ⁇ -epoxypropyloxy)diphenylmethane, 4,4′-bis(2 ⁇ ,3 ⁇ -e
• the organic compounds having at least one aziridinyl group are preferably selected from the group consisting of 2,4-bis(1-aziridinylcarbonylamino)toluene, bis[4-(1-aziridinylcarbonylamino)phenyl]methane, bis[3-chloro-4-(1-aziridinylcarbonylamino)phenyl]methane, 2,2-bis[4-(1-aziridinylcarbonyloxy)phenyl]propane, 1,4-bis(1-aziridinylcarbonyl)benzene.
• the dye precursor usable for the present invention comprises at least one member selected form conventional triphenylmethane, fluoran and diphenylmethane leuco dyes, for example, 3-(4-diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methylindole-3-il)-4-azaphthalide, crystal violet lactone, 3-(N-ethyl-N-isopentylamino)-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-(2′,4′-dimethyl-anilino) fluoran, 3-(N-ethyl-N-p-toluidino)-6-methyl-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3-(N-
• the color-developing agent usable for the present invention optionally comprises, in addition to the aromatic sulfon(thio)amide compound, at least one conventional acid compound selected from phenolic compounds and organic acid compounds, for example, 2,2-bis(4-hydroxyphenyl) propane(bisphenol A), 1,1-bis(4-hydroxyphenyl)-1-phenyl-ethane, 1,4-bis[1-methyl-1-(4′-hydroxy-phenyl)ethyl] benzene, 1,3-bis[1-methyl-1-(4′-hydroxyphenyl)ethyl] benzene, dihydroxydiphenylether (JP-A-1-180,382), benzyl p-hydroxybenzoate (JP-A-52-140,483), bis-phenol S, 4-hydroxy-4′-iso propyloxydiphenyl-sulfone(JP-A-60-13,852), 1,1-di(4-hydroxy-phenyl) cyclohexane, 1,7-
• the aromatic sulfon(thio)amide compound is present in an amount of 50% to 100% based on the total weight of the color developing agent.
• thermosensitive colored image-forming layer of the present invention optionally further comprises a heat-fusible organic substance, usually referred to as a sensitizing agent.
• This sensitizing agent comprises at least one organic compound having a melting point of from 50°C to 160°C, for example, phenyl 1-hydroxy-2-naphthoate (JP-A-57-191,089), p-benzyl-biphenyl (JP-A-60-82,382), benzyl-naphthylether (JP-A-58-87,094), dibenzyl terephthalate (JP-A-58-98,285), benzyl p-benzyloxybenzoate (JP-A-57-201,691), diphenyl carbonate, ditolyl cabonate (JP-A-58-136,489), m-terphenyl (JP-A-57-89,994), 1,2-bis(m-tolyloxy) e
• thermosensitive colored image-forming layer of the present invention optionally further comprises at least one member selected from hindered phenolic compounds and ultraviolet ray-absorbers, as disclosed, for example, in JP-A-57-151,394, JP-A-58-160,191, JP-A-58-69,096, JP-A-59-2,884, JP-A-59-95,190, JP-A-60-22,288, JP-A-60-255,485, JP-A-61-44,686, JP-A-62-169,683, JP-A-63-17,081, and JP-A-1-249,385.
• hindered phenolic compounds and ultraviolet ray-absorbers as disclosed, for example, in JP-A-57-151,394, JP-A-58-160,191, JP-A-58-69,096, JP-A-59-2,884, JP-A-59-95,190, JP-A-60-22,288, JP-A-60-255
• the phenolic compounds and ultraviolet ray-absorbers are preferably selected from 1,1,3-tris(3′-cycloxyl-4′-hydroxyphenyl)butane; 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 4,4′-thio-bis(3-methyl-6-tert-butylphenol), 1,3,5-trimethyl-2,4-6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, p-octylphenyl salycilate, 2-(2′-hydroxy-5′-methylphenyl)benzotriazole, ethyl 2-cyano-3,3′-diphenyl acrylate, and tetra(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butane-tetracarbonate.
• the thermosensitive colored image-forming layer comprises a dye precursor, a color-developing agent comprising at least one aromatic sulfonyl(thio)amide compound the formulae (I) and/or (II), a binder, and optionally, a colored image-stabilizing agent comprising at least one member selected from the epoxy group-having aromatic compounds and the aziridinyl group-having organic compounds.
• thermosensitive colored image-forming layer of the present invention optionally further contains an additive comprising at least one member selected from, for example, conventional color-developing phenolic and organic acid compounds, sensitizing agents, antioxidants, ultraviolet ray-absorbers, waxes, and organic and inorganic pigments.
• an additive comprising at least one member selected from, for example, conventional color-developing phenolic and organic acid compounds, sensitizing agents, antioxidants, ultraviolet ray-absorbers, waxes, and organic and inorganic pigments.
• the dye precursor is present in an amount of 5 to 40% by weight
• the color-developing aromatic sulfonyl(thio)amide compound is present in an amount of 10 to 50% by weight
• the binder is present in an amount of 5 to 20% by weight.
• the above-mentioned amounts are based on the total dry weight of the thermo sensitive colored image-forming layer. If the amount of the color-forming aromatic sulfonyl(thio)amide compound is less than 10% by weight, the resultant colored image-forming layer sometimes exhibits an unsatisfactory color-developing effect. Also, an amount of the color-developing aromatic sulfonyl(thio)amide compound exceeding 50% by weight is not effective for further increasing the color-developing power of the resultant color image-forming layer.
• the colored image-stabilizing agent comprising the epoxy group-having aromatic compound and/or the aziridinyl group-having organic compound, is present in an amount of 1 to 30% by weight in the thermosensitive colored image-forming layer.
• the presence of the colored image-stabilizing agent in an amount of less than 1% does not impart a satisfactorily high persistency to the resultant colored images, and an amount of the colored image-stabilizing agent of more than 30% by weight does not effectively further enhance the storage durability of the resultant colored images.
• the antioxidant or ultraviolet ray absorber is optionally preferably contained in an amount of 1 to 10% by weight in the thermosensitive colored image-forming layer.
• An amount of the antioxidant or ultraviolet ray absorber of less than 1% by weight does not satisfactorily and effectively prevent a fading or discoloring of the colored images. Further, an amount of more than 30% by weight of the antioxidant or ultraviolet ray absorber causes a reduction of the whiteness of the resultant colored image-forming layer, and sometimes hinders the ease of travel of the resultant recording material in a printer.
• the conventional color-developing phenolic or organic acid compound is optionally preferably contained in an amount of 5 to 40% in the colored image-forming layer.
• the sensitizing agent is optionally preferably contained in an amount of 10 to 40% by weight, and the wax and organic or inorganic pigment are optionally contained in amounts of 5 to 20% by weight and 10 to 50% by weight, respectively.
• the wax usable for the present invention preferably comprises at least one member selected from, for example, paraffin waxes, carnauba wax, microcrystalline waxes, polyethylene waxes, amide type waxes, bisimide type waxes, higher fatty acid amide waxes, for example, stearic acid amide, ethylene-bis-stearoamide wax, higher fatty acid esters and metal salts, for example, zinc stearate, aluminum stearate calcium stearate and zinc oleate.
• the inorganic and organic pigments usable for the present invention are preferably selected from inorganic fine particles of, for example, calcium carbonate, silica, zinc oxide, titanium dioxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, anhydrous clay, talc, and surface-treated calcium carbonate and silica and organic fine particles of, for example, urea-formaldehyde resins, styrene-methacrylate copolymer resins and polystyrene resins.
• the binder preferably comprises at least one member selected from water-soluble polymeric materials, for example, various types of polyvinyl alcohol resins which have a different molecular weight from each other, starch and starch derivatives, cellulose derivatives, for example, methoxy cellulose, carboxymethyl cellulose, methyl cellulose and ethyl cellulose, sodium polyacrylate, polyvinyl pyrrolidine, acrylic acid amide-acrylic acid ester copolymers, acrylic acid amide-acrylic acid ester-methacrylic acid terpolymers, alkali salts of styrene-maleic anhydride copolymers, polyacrylic acid amide, sodium alginate, gelatine and casein, and water-insoluble polymeric materials, for example, polyvinyl acetate resins, polyurethane resins, styrene-butadiene copolymer resins, polyacrylic acid resins, polyacrylic acid ester resins, vinyl chloride-vinyl acetate copo
• the sheet substrate usable for the present invention is not limited to a specific group of materials, and usually the sheet substrate comprises a member selected from fine paper sheets, coated paper sheet having a clay or plastic coating layer, cast-coated paper sheets, paper boards, plastic resin films, synthetic paper sheets comprising a plastic resin, and laminated paper sheets.
• the sheet substrate has a basis weight of 40 to 170 g/m2.
• the colored image-forming layer can be formed on a surface of a sheet substrate, by applying a coating liquid containing the above-mentioned components, and by drying and solidifying the coating liquid layer on the sheet substrate.
• the colored image-forming layer is preferably present in a dry weight of from 1 to 15 g/m2, more preferably 2 to 10 g/m2.
• thermosensitive recording material a protective layer and/or a printed layer may be formed on the colored image-forming layer.
• a three necked flask equipped with a dropping funnel, a thermometer, and a reflux condenser was charged with 10 g of p-toluenesulfonamide.
• the p-toluene-sulfonamide was dissolved in 20 ml of pyridine, and to the resultant reaction solution were dropwise added 9.5 g of o-toluoyl chloride, while the flask was cooled in an ice bath, and the reaction mixture was stirred by using a magnetic stirrer. This dropwise addition was carried out at a temperature of 20°C or less, and after the dropwise addition was completed, the temperature of the reaction mixture was gradually restored to room temperature.
• the ice bath was then replaced by a heating oil bath, and the flask placed in the heating oil bath to heat the reaction mixture at a temperature of 140°C for 3 hours.
• the resultant reaction product was washed with IN hydrochloric acid solution and extracted with ethyl ether.
• the extracted ethyl ether solution was washed with water, dried over magnesium sulfate, and filtered, and the resultant filtered solution was solidified by evaporating away ethyl ether, to obtain 13 g of light yellow crystals as the product.
• the crystals were recrystallized by using toluene, and a white crystalline substance was obtained in an amount of 12 g, and exhibited a melting point of 118°C.
• a three necked flask equipped with a dropping funnel, a thermometer and a reflux condenser was charged with 10 g of p-toluenesulfonamide.
• the p-toluenesulfonamide was dissolved in 20 ml of pyridine, and to the resultant reaction solution was dropwise added a solution of 8.7 g of phenyl chlorocarbonate in 10 ml of toluene, while the flask was cooled in an ice bath and the reaction mixture was stirred by using a magnetic stirrer. This dropwise addition was carried out at a temperature of 20°C or less.
• the temperature of the reaction mixture was gradually restored to room temperature, and then the ice bath was replaced by a heating oil bath, and the flask was placed in the heating oil bath to heat the reaction mixture at a temperature of 100°C for 3 hours.
• the resultant reaction product was washed with IN hydrochloric acid solution and extracted with ethyl ether.
• the extracted ethyl ether solution was washed with water, dried over magnesium sulfate, and filtered, and the ethyl ether in the resultant filtered solution was evaporated to obtain a toluene solution of the reaction product.
• a small amount of fresh toluene was added to the toluene solution, and the solution was subjected to a recrystallization process.
• the product was 11.5 g of white crystals having a melting point of 106°C.
• a three necked flask equipped with a dropping funnel, a thermometer and a reflux condenser was charged with 5.0 g of hydroquinone-monobenzylether.
• the hydroquinone monobenzyl ether was dissolved in 20 ml of toluene at a temperature of 80°C, and to the resultant reaction solution was dropwide added 5.2 g of p-toluenesulfonyl isocyanate. After the dropwise addition was completed, several drops of pyridine were added to the reaction mixture, and the resultant reaction mixture was maintained at a temperature of 80°C for 2 hours.
• thermosensitive recording paper sheet was prepared by the following procedures.
• composition was dispersed in a sand grinder to an extent such that the resultant dispersed solid particles had an average size of 1 ⁇ m or less.
• composition was dispersed in a sand grinder to an extent such that the resultant dispersed solid particles had an average size of 1 ⁇ m or less.
• a coating liquid was prepared by mixing an aqueous dispersion, prepared by dispersing 85 parts by weight of anhydrous clay available under the trademark of Ansilex, from Engelhard Corporation, in 320 parts by weight of water, with 40 parts by weight of an aqueous emulsion of a styrene - butadiene copolymer in a solid concentration of 50% by weight and 50 parts by weight of a 10% aqueous oxidized starch solution.
• the coating liquid was coated on a surface of a fine paper sheet having a basis weight of 48 g/m2, to form a coating layer having a dry weight of 7.0 g/m2, whereby coated paper sheet was obtained.
• a coating liquid was prepared by evenly mixing 80 parts by weight of the aqueous dye precursor dispersion A and 160 parts by weight of the aqueous color-developing agent dispersion B with 30 parts by weight of a calcium carbonate pigment, 20 parts by weight of a 25% aqueous zinc stearate dispersion, 15 parts by weight of a 30% aqueous parafin dispersion, and 120 parts by weight of a 10% aqueous polyvinyl alcohol solution, by agitating the mixture.
• thermosensitive colored image-forming layer was formed in a weight of 5.0 g/m2, to provide a thermosensitive recording paper sheet.
• the recording sheet was treated by a super calender, and the calendered surface of the recording sheet had a Bekk smoothness of 600 to 1000 seconds.
• thermosensitive recording sheet A specimen of the resultant thermosensitive recording sheet was tested by a thermal inclination tester made by Toyoseiki Co., at a temperature of 120°C under a pressure of 2.5 kg/cm2 for one second, to color develop the thermosensitive colored image-forming layer thereof, and as a result, a clear black colored image was found to have a high color density of more than 1.2 as determined by Macbeth Reflection Color Density Tester - 914 (trademark), as shown in Table 1.
• the non-color developed portions of the tested colored image-forming layer were subjected to a whiteness test by using a Hunter Whiteness Tester (trademark) with a blue filter.
• Example 2 The same procedures as in Example 1 were carried out except that, in the preparation of the aqueous color developing agent dispersion B, N-(o-toluoyl)-p-toluenesulfonamide was replaced by N-benzoyl-o-toluenesulfonamide.
• Example 2 The same procedures as in Example 1 were carried out except that, in the preparation of the aqueous color-developing agent dispersion B, N-(o-toluoyl)-p-toluenesulfonamide was replaced by N-benzoyl-o-toluenesulfonamide.
• Example 2 The same procedures as in Example 1 were carried out except that, in the preparation of the aqueous color-developing agent dispersion B, N-(o-toluoyl)-p-toluenesulfonamide was replaced by a conventional color-developing agent consisting of 2,2-bis(4-hydroxyphenyl)propane, namely bisphenol A.
• Example 3 The same procedures as in Example 3 were carried out except that, in the preparation of the aqueous color-developing agent dispersion B, N-(0-toluoyl)-p-toluenesulfonamide was replaced by N-benzoyl-o-toluenesulfonamide.
• Example 3 The same procedures as in Example 3 were carried out except that, in the preparation of the aqueous color-developing agent dispersion B, N-(o-toluoyl)-p-toluenesulfonamide was replaced by N-palmitoyl-p-toluenesulfonamide.
• Example 3 The same procedures as in Example 3 were carried out except that, in the preparation of the aqueous colored image-stabilizing agent dispersion C, bis[4-(1-aziridinylcarbonylamino)phenyl]methane was replaced by 2,4-bis(1-aziridinylcarbonylamino)toluene.
• the coating liquid for the colored image-forming layer was prepared by mixing 40 parts by weight of the aqueous dye precursor dispersion A, 80 parts by weight of the aqueous color-developing agent dispersion B and 70 parts by weight of the aqueous colored image-stabilizing agent dispersion C with 40 parts by weight of a calcium carbonate pigment, 20 parts by weight of a 25% zinc stearate dispersion, 15 parts by weight of a 30% parafin dispersion and 120 parts by weight of a 10% polyvinyl alcohol solution, while stirring.
• the coating liquid was applied to a surface of a fine paper sheet having a basis weight of 48 g/m2, to form a thermosensitive colored image-forming layer having a dry weight of 7.0 g/m2.
• thermosensitive recording sheet The test results of the resultant thermosensitive recording sheet are shown in Table 2.
• Example 3 The same procedures as in Example 3 were carried out except that, in the preparation of the aqueous dye precursor dispersion A, 3-(N-isopentyl-N-ethylamino)-6-methyl-7-anilino-fluoran was replaced by 3-dibutylamino-6-methyl-7-anilinofluoran.
• thermosensitive recording sheet The test results of the resultant thermosensitive recording sheet are shown in Table 2.
• Example 3 The same procedures as in Example 3 were carried out except that, in the preparation of the aqueous color-developing agent dispersion, N-(o-toluoyl)-p-toluenesulfonamide was replaced by 2,2-bis(4-hydroxyphenyl)propane, namely bisphenol A.
• thermosensitive recording sheet The test results of the resultant thermosensitive recording sheet are shown in Table 2.
• the color density (D) of the resultant colored image was measured by using a Macbeth Reflection Color Density Tester RD - 914 (Trademark).
• the whiteness of the non-colored portion of the tested recording sheet was measured by using a Hunter Whiteness Tester with a blue filter.
• Example 9 The same procedures as in Example 9 were carried out except that, in the preparation of the aqueous color-developing agent dispersion B-a, p-cumylphenyl N-(p-toluenesulfonyl)carbamate having a melting point of 120°C was replaced by p-benzyloxyphenyl N-(p-toluenesulfonyl)carbamate having a melting point of 126°C.
• Example 9 The same procedures as in Example 9 were carried out except that, in the preparation of the aqueous color-developing agent dispersion B-a, p-cumylpheny N-(p-toluenesulfonyl)carbamate was replaced by 2,2-bis(4-hydroxyphenyl)propane, namely bisphenol A, having a melting point of 156°C.
• Example 11 The same procedures as in Example 11 were carried out except that, in the preparation of the aqueous color-developing agent dispersion B-a, p-cumylphenyl N-(p-toluenesulfonyl) carbamate having a melting point of 120°C was replaced by p-benzyloxyphenyl N-(p-toluenesulfonyl) carbamate having a melting point of 126°C.
• Example 11 The same procedures as in Example 11 were carried out except that, in the preparation of the aqueous colored image-stabilizing agent dispersion C, bis[4-(1-aziridinylcarbonylamino)phenyl]methane was replaced by 2,4-bis(1-aziridinyl-carbonylamino)toluene.
• Example 12 The same procedures as in Example 12 were carried out except that, in the preparation of the aqueous dye precursor dispersion A, 3-(N-isopentyl-N-ethylamino)-6-methyl-7-anilinoflnoran was replaced by 3-dibutylamino-6-methyl-7-anilinoflnoran.
• Example 11 The same procedures as in Example 11 were carried out except that, in the preparation of the aqueous color-developing agent dispersion B-a, p-cumylphenyl N-(p-toluenesulfonyl)carbamate having a melting point of 120°C was replaced by 2,2-bis(4-hydroxyphenyl)propane, namely bisphenol A.
• Example 11 The same procedures as in Example 11 were carried out except that, in the preparation of the aqueous color-developing agent dispersion B-a, p-cumylphenyl N-(p-toluenesulfonyl)carbomate having a melting point of 120°C was replaced by 4-tert-butylphenyl N-phenylcarbamate as disclosed in JP-A-60-184,874.
• the color density of the remaining colored image was measured by a Macbeth Reflection Color Density Tester.
• the measured color density value is referred to as an after test color density value D′.
• Example 16 The same procedures as in Example 16 were carried out except that, in the preparation of the aqueous color-developing agent dispersion B-a, p-cumylphenyl N-(p-toluenesulfonyl)carbamate having a melting point of 120°C was replaced by p-benzyloxyphenyl N-(p-toluenesulfonyl)carbamate having a melting point of 126°C.
• Example 16 The same procedures as in Example 16 were carried out except that, in the preparation of the aqueous color-developing agent dispersion B-a, p-cumylphenyl N-(p-toluenesulfonyl) carbamate having a melting point of 120°C was replaced by N-(o-toluoyl)-p-toluenesulfonamide having a melting point of 118°C.
• Example 17 The same procedures as in Example 17 were carried out except that, in the preparation of the aqueous colored image-stabilizing agent dispersion C-a, 4,4′-bis(2 ⁇ ,3 ⁇ -epoxypropyloxy)diphenylsulfone was replaced by bis(2,3-epoxypropyl)terephthalate.
• Example 17 The same procedures as in Example 17 were carried out except that, in the preparation of the aqueous colored image-stabilizing agent dispersion C-a, 4,4′-bis(2 ⁇ ,3 ⁇ -epoxypropyloxy)diphenylsulfone was replaced by 4-(2′-methyl-2′,3′-epoxypropyloxy)-4′-benzyloxy-diphenylsulfone.
• Example 16 The same procedures as in Example 16 were carried out except that, in the preparation of the aqueous colored image-stabilizing agent dispersion C-a, 4,4′-bis(2 ⁇ ,3 ⁇ -epoxypropyloxy)diphenylsulfone was replaced by an epoxidized novolak cresol resin (available under the trademark of Denacol EM-125, from Nagase Kasei.)
• an epoxidized novolak cresol resin available under the trademark of Denacol EM-125, from Nagase Kasei.
• Example 16 The same procedures as in Example 16 were carried out except that, in the preparation of the aqueous dye precursor dispersion A, 3-(N-isopentyl-N-ethylamino)-6-methyl-anilinofluoran was replaced by 3-dibutylamino-6-methyl-7-anilinofluoran.
• Example 19 The same procedures as in Example 19 were carried out except that, in the preparation of the aqueous color-developing agent dispersion, p-benzyloxyphenyl N-(p-toluenesulfonyl)carbamate was replaced by 2,2-bis(4-hydroxyphenyl)propane, namely bisphenol A.
• Example 16 The same procedures as in Example 16 were carried out except that, in the preparation of the aqueous color-developing agent dispersion B-a, p-cumylphenyl N-(p-toluenesulfonyl)carbamate having a melting point of 120°C was replaced by (4-hydroxyphenyl)sulfone, namely bisphenol S.
• Table 1 clearly shows that the new color-developing compounds of the formula (I) have a color-developing capability comparable with bisphenol A, which is a typical conventional color-developing agent, and the resultant thermosensitive colored image-forming layer exhibits a significantly higher whiteness than that of the conventional colored image-forming layer containing bisphenol A.
• Table 2 clearly shows that, when the color-developing compound of the present invention is employed together with a colored image-stabilizing agent comprising an aziridinyl compound, the resultant colored image exhibits a high resistance to oily or fatty substances and to a plasticizer, even immediately after the completion of the color development.
• Table 3 clearly shows that the color-developing compounds of the formula (I) exhibit an excellent color-developing activity higher than that of bisphenol A, and the resultant colored image-forming layer has a superior whiteness significantly higher than that of the conventional bisphenol A - containing colored image - forming layer.
• Table 4 shows that the employment of the colored image-stabilizing agent comprising an aziridinyl compound, in combination with the specific color-developing compound of the present invention, is highly effective for enhancing the oil and plasticizer resistance of the resultant colored images, even immediately after the color development thereof.
• Table 5 clearly indicates that, when the specific color-developing compounds of the formulae (I) and (II) of the present invention are used together with an aromatic epoxy compound, the resultant color images exhibit a superior resistance to oils and plasticizers, and the resultant colored image-forming layer exhibits a satisfactory whiteness, whereas a combination of a conventional phenolic color-developing agent with an aromatic epoxy compound usually causes the resultant colored image-forming layer to exhibit a lowered whiteness and an undesirably enhanced ground color-developing property at a relatively low temperature.

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• 1992
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