JP2001071644A - Heat-sensitive multiple copy sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-sensitive multiple copy sheet having high recording density of each recording sheet and excellent image quality of a recorded part of a heat-sensitive recording layer of an upper recording sheet. SOLUTION: In the heat-sensitive multiple copy sheet obtained by sequentially superposing an upper recording sheet having a heat-sensitive recording layer containing a leuco dye and a colorant on a front surface of an upper base material sheet, an intermediate recording sheet having a heat-sensitive recording layer containing a leudo dye and a colorant on a front surface of an intermediate base material sheet and having a thermal transfer layer containing a leuco dye and a thermoplastic organic compound, and a lower recording sheet having a thermal transfer receiving layer containing a colorant and an adhesive on a front surface of a lower base material sheet, an organic compound having a sulfonyl group as a colorant and a melting point of 150 to 250 deg.C is contained in the recording layer of the upper recording sheet, and a hydrophobic acrylic resin having a mean molecular weight of 5,000,000 or more is contained as an adhesive in the recording layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive multiplex copy sheet capable of simultaneously performing heat-sensitive recording on a plurality of sheets.

[0002]

2. Description of the Related Art A thermosensitive recording medium is known which utilizes a color reaction between a leuco dye and a coloring agent to react both coloring materials with heat energy from a thermal head to obtain a recorded image. . Such a thermosensitive recording medium is relatively inexpensive, has a compact recording device, and is easy to maintain. Therefore, it is used not only as a recording medium for facsimile and various computing devices but also in a wide range of fields. In particular, since the thermal recording medium has been used as a receipt or delivery note, there has been an increasing demand for a thermal recording medium capable of recording on a plurality of sheets with a single thermal recording.

However, when energy necessary for obtaining a sufficient recording density for a large number of sheets is applied to the heat-sensitive recording layer of the upper-leaf recording sheet, the recording portion of the heat-sensitive recording layer of the upper-leaf recording sheet is colored. A white spot phenomenon due to decomposition, sublimation, etc. of the material appears. In order to suppress such white spots, Japanese Patent Laid-Open No. Hei 11 (1999) discloses a heat-sensitive multiple copy sheet in which the heat-sensitive recording layer of the upper leaf recording sheet contains an organic compound having a molecular weight of 250 or more as a colorant.
Although it is described in JP-A-34491, there is a demand for further improvement in the recording runnability and white spots.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive multiplex copy sheet which has a high recording density on each recording sheet and is excellent in the image quality of the recording portion of the heat-sensitive recording layer of the upper leaf recording sheet and the recording running property. Is to provide.

[0005]

Means for Solving the Problems An upper leaf recording sheet having a heat-sensitive recording layer containing a leuco dye and a coloring agent on the front surface of the upper leaf base sheet, and a leuco dye on the front surface of the middle leaf substrate sheet. A middle-leaf recording sheet having a heat-sensitive recording layer containing a colorant, and a thermal transfer layer containing a leuco dye and a heat-fusible organic compound on the back surface, and a colorant on the front surface of the lower-leaf base material sheet and an adhesive. Transfer sheet containing a lower transfer sheet having a thermal transfer receiving layer containing a heat-sensitive agent, or a thermal transfer sheet containing a leuco dye and a heat-fusible organic compound on the back side of the upper leaf record sheet of the above heat-sensitive copy sheet. Heat-sensitive multiplex copy sheet provided with a layer, or upper leaf recording sheet with a leuco dye and a heat-fusible organic compound-containing heat transfer layer on the back side of the upper leaf recording sheet, coloration on the front side of the middle leaf base sheet Contains adhesive and adhesive A middle-leaf recording sheet having a thermal transfer receiving layer and a thermal transfer layer containing a leuco dye and a heat-fusible organic compound on the back surface, and a thermal transfer containing a colorant and an adhesive on the front surface of the lower leaf base sheet In a heat-sensitive multiplex copy sheet in which lower leaf recording sheets having a receiving layer are sequentially stacked,
As a means for solving the above-mentioned problems, the present invention provides a heat-sensitive recording layer of an upper leaf recording sheet having a melting point of 1 as a colorant.
Containing a sulfonyl organic compound at 50 to 250 ° C.,
The adhesive contains a hydrophobic acrylic resin having an average molecular weight of 5,000,000 or more.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a heat-sensitive multiplex copying sheet having at least an upper leaf recording sheet, a middle leaf recording sheet and a lower leaf recording sheet, and has a melting point as a colorant in a thermosensitive recording layer of the upper leaf recording sheet. Contains a sulfonyl-based organic compound at 150 to 250 ° C. (hereinafter, referred to as a specific colorant), and has an average molecular weight of 5,000,000 or more as an adhesive. )
Wherein the specific colorant has a melting point of 1
If the temperature is lower than 50 ° C., the specific colorant in the heat-sensitive recording layer of the upper recording sheet may be decomposed or sublimated by the thermal energy of the thermal head during recording, so that the image quality of the recording portion may be remarkably deteriorated. If the density exceeds, the density of the recording portion recorded on the heat-sensitive recording layer of the upper leaf recording sheet may be lowered.

The average molecular weight of a specific adhesive is 500
If it is less than 10,000, sticking may occur at the time of recording, and the recording traveling property may be reduced.
About 8 to 12 million is preferable. If it exceeds 12,000,000, the synthesis itself becomes difficult and the adhesive strength may be reduced.

The average molecular weight of a specific acrylic resin can be measured by gel permeation chromatography. However, if the average molecular weight exceeds 10,000,000, the measured value may be unclear, and the specific molecular weight may exceed 10,000,000. Acrylic resin has an average molecular weight of 10
Million or more.

The specific acrylic resin is prepared by converting a monomer containing at least a (meth) acrylic acid ester and an ethylenically unsaturated carboxylic acid under a condition that the oxygen concentration is lower than the oxygen concentration of a 0.5% aqueous sodium bisulfite solution. It is obtained as an aqueous adhesive (latex) by emulsion polymerization and used in the form of a latex.

Examples of the (meth) acrylate include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and methacrylic acid. -2-ethylhexyl and the like.

As the ethylenically unsaturated carboxylic acid, for example, acrylic acid, methacrylic acid, itaconic acid, maleic acid and the like can be mentioned.

In addition, as long as the desired effect of the present invention is not impaired, acrylonitrile, butadiene, isoprene, styrene, α-methylstyrene, vinyl chloride, acrylamide, N-methylolacrylamide may be used as a monomer during the emulsion polymerization. Can also be added.
Of these, acrylonitrile is preferred.

The proportion of each monomer is not particularly limited, but is preferably, for example, about 1 to 30 parts by weight of an ethylenically unsaturated carboxylic acid per 100 parts by weight of (meth) acrylate.

In the emulsion polymerization, an anionic or nonionic emulsifier and a redox polymerization initiator are used. The amount of the emulsifier used is about 0.5 to 5.0% by weight based on all monomers. Further, the amount of the redox polymerization initiator to be used is 0.1 to all monomers.
It is about 0.1 to 0.1% by weight.

The amount of the specific colorant and the specific adhesive is not particularly limited, but the specific colorant is preferably about 10 to 40% by weight based on the heat-sensitive recording layer.
The specific adhesive is preferably about 5 to 35% by weight. In particular, for certain colorants, it is 10% by weight.
If it is less than 40%, the storage stability of the recording part is reduced,
Exceeding the range may cause a decrease in recording traveling performance.

The leuco dyes contained in the heat-sensitive recording layer and the heat transfer layer include, for example, the following compounds.
3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2)
-Methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3-diethylamino-7-dibenzylaminofluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3- Diethylamino-7-chlorofluoran, 3-diethylamino-7-anilinofluoran, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluoran, 3-diethylamino-7- ( m-trifluoromethylanilino) fluoran, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3 -Di (n-butyl) amino-6-methyl-7-anilinofluoran, 3-di (n-pentyl) amino-6-methyl 7-anilinofluoran, 3-diethylamino -7- (o- chloroanilino) fluoran,
3-di (n-butyl) amino-7- (o-chloroanilino) fluoran, 3-di (n-butyl) amino-7-
(O-fluoroanilino) fluoran, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-pepyridino -6-methyl-7-anilinofluoran, 3,3-bis [1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-2-yl] -4,5,6,7 -Tetrachlorophthalide, 3,6-bis (dimethylamino) fluorene-9
-Spiro-3 '-(6'-dimethylamino) phthalide,
3- (N-ethyl-N-2-tetrahydrofurfuramino) -6-methyl-7-anilinofluoran, 3- (4
-Dimethylamino) anilino-5,7-dimethylfluoran and the like

Of course, it is not limited to these,
If necessary, two or more kinds can be used in combination. The amount of the leuco dye used is about 5 to 35% by weight based on the total solids of the heat-sensitive recording layer in the heat-sensitive recording layer, and 3 to 50% by weight based on the total solids of the heat-transfer layer in the thermal transfer layer.
% By weight.

Specific colorants contained in the heat-sensitive recording layer of the upper leaf recording sheet include, for example, the following compounds. 4,4′-dihydroxydiphenyl sulfone (melting point 248 ° C.), 2,4′-dihydroxydiphenyl sulfone (melting point 183 ° C.), bis (3-allyl-4-hydroxyphenyl) sulfone (melting point 151 ° C.), 2,4- Bis (phenylsulfonyl) phenol (melting point 157 ° C),
4,4′-bis (p-tolylsulfonylaminocarbonylamino) diphenylmethane (melting point: 155 ° C.), etc. Of course, two or more of such colorants can be used, provided that the desired effects of the present invention are not impaired. Various other known colorants can be used in combination.

Examples of the coloring agent contained in the heat-sensitive recording layer and the heat transfer receiving layer of the middle leaf recording sheet include the following compounds. Acid clay, activated clay, attapulgite, zeolite, acidic clays such as bentonite, 4,
4′-isopropylidene diphenol, 2,2-bis (4-hydroxyphenyl) -4-methylpentane,
4,4'-cyclohexylidenediphenol, 2,4 '
-Dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, bis (3-allyl-
4-hydroxyphenyl) sulfone, 4-hydroxy-
4'-benzyloxydiphenyl sulfone, 2,4-bis (phenylsulfonyl) phenol, 2,2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] diethyl ether, 1,1-bis (4-hydroxyphenyl) ) Phenolic compounds such as 1-phenylethane, 4-hydroxybenzoic acid-p-methoxybenzyl, novolak type phenolic resin, phenolic polymer and the like;
-Tert-butylsalicylic acid, zinc 3-benzylsalicylate, zinc 3- (α-methylbenzyl) salicylate, 3,
Zinc 5-di-tert-butylsalicylate, 3,5-di (α
-Methylbenzyl) zinc salicylate, 3-phenyl-5
-(Α, α-dimethylbenzyl) zinc salicylate, 3,
Zinc 5-di-tert-octylsalicylate, 3,5-di-te
Zinc rt-nonyl salicylate, zinc 5-cyclohexylsalicylate, zinc 4- [2- (p-methoxyphenoxy) ethyloxy] salicylate, zinc 4- [3- (p-tolylsulfonylpropyloxy) salicylate, 5- [p-
(2-p-methoxyphenoxyethoxy) cumyl] zinc salicylate, mono [poly (0-4) [ω-hydro [poly (1-7) α-methylbenz] -α-yl] benzyl]
Zinc salts of salicylic acid derivatives such as zinc salicylate;
p-tolylsulfonyl-N'-phenylurea, 4,4 '
Compounds having a sulfamide bond in the molecule such as -bis (p-tolylsulfonylaminocarbonylamino) diphenylmethane and the like. Of course, the compounds are not limited to these, and two or more of them can be used in combination as needed. The amount of the coloring agent used is about 5 to 50% by weight for the heat-sensitive recording layer and 10 to 70% by weight for the thermal transfer receiving layer.

In particular, the following sensitizer is preferably contained in the heat-sensitive recording layer of the middle leaf recording sheet in an amount of about 5 to 40% by weight based on the heat-sensitive recording layer in order to increase the recording sensitivity. m-
Terphenyl, di-p-methylbenzyl oxalate, di-p-chlorobenzyl oxalate, dibenzyl terephthalate, phenyl 1-hydroxynaphthoate, 1,2-di- (3-methylphenoxy) ethane , 1,2-diphenoxyethane, 1-phenoxy-2-naphthoxyethane, p-benzylbiphenyl.

The heat-sensitive recording layer is generally composed of water as a medium, a leuco dye finely dispersed to an average particle size of about 0.1 to 3 μm, a specific colorant, and, if necessary, a sensitizer, a preservability improver and the like. And a specific adhesive are mixed and stirred, and the coating liquid for the heat-sensitive recording layer obtained on the front surface of the upper-leaf (middle-leaf) base sheet is dried, and the coated amount is about ² to 7 g / m ^2. Is formed by coating and drying.

In the coating solution for the heat-sensitive recording layer, various other known adhesives can be used in combination as long as the desired effects of the present invention are not impaired. Examples of such an adhesive include the following. Complete (partial) saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, styrene-maleic acid copolymer salt, ethylene-acrylic acid copolymer salt, isobutylene, maleic acid Water-soluble resin such as a polymer salt, and an acrylic latex having an average molecular weight of less than 5 million,
Water-dispersible resins such as urethane latex, styrene-butadiene latex, and vinyl acetate latex are exemplified.

If necessary, pigments such as kaolin, calcium carbonate, amorphous silica, titanium oxide, aluminum hydroxide, calcined kaolin and zinc oxide, paraffin wax, polyethylene wax,
Lubricants such as stearic acid amide, ethylenebisstearic acid amide, stearic acid amide, zinc stearate, calcium stearate, and 1,1,3-tris (2-
Methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, N,
It is also possible to add storage stability improvers such as N'-di-2-naphthyl-p-phenylenediamine for improving the storage stability of the recording portion, and a fluorescent dye, a coloring dye, a surfactant, a water-proofing agent and the like. it can.

The thermal transfer layer formed on the back surface of the middle leaf (upper leaf) base sheet contains the following heat-fusible organic compound together with the above-mentioned leuco dye. It is not particularly limited as long as it is an organic compound having a melting point of about 35 to 150 ° C., for example, carnauba wax, montan wax, paraffin wax, microcrystalline wax, polyethylene wax, palmitic acid,
Higher aliphatic compounds such as stearic acid, behenic acid stearic acid amide, ethylenebisstearic acid amide, methyl stearate, and stearic anilide are excellent in pressure-sensitive recording properties and are preferred. The amount of the heat-fusible organic compound used is about 30 to 90% by weight based on the total solid content of the thermal transfer layer. Preferably, it is about 40 to 80% by weight.

The thermal transfer layer is generally formed by coating a heat-fusible organic compound on the back surface of a middle-leaf (upper-leaf) base sheet with a heat-fusible organic compound.
It is formed by coating by, for example, a hot melt method so as to be about g / m ² .

The heat transfer receiving layer is prepared by mixing and stirring a colorant, an adhesive, and, if necessary, the following auxiliary agents which are finely dispersed in an average particle diameter of about 0.1 to 3 μm using water or an organic solvent as a medium. The coated amount after drying the heat transfer receiving layer coating solution obtained on the back surface of the lower leaf base sheet or the middle leaf base sheet is 2 to 2.
It is formed by coating and drying so as to have a weight of about 7 g / m ² .

As the adhesive contained in the thermal transfer receiving layer, an adhesive which can be used for the above-mentioned heat-sensitive recording layer can be used. Further, an auxiliary agent that can be added to the heat-sensitive recording layer may be added to the thermal transfer receiving layer.

In the coating solution for the thermal transfer receiving layer, pigments, lubricants, preservatives, fluorescent dyes, coloring dyes, surfactants, and water-resistant materials which can be further contained in the coating solution for the heat-sensitive recording layer. Agents and the like can be contained.

The coating solution for the heat-sensitive recording layer and the coating solution for the thermal transfer receiving layer include, for example, an air knife, a Meyer bar, a pure blade, a rod blade, a reverse roll, a gravure,
It is applied by a coating method such as a slit die and a curtain.

The thermal transfer layer is generally formed by applying a coating liquid for a thermal transfer layer in which a leuco dye is added to a heat-soluble heat-soluble organic compound to the back of the upper leaf base sheet and the middle leaf base sheet.
It is formed by applying, for example, a hot melt method so as to have a weight of about 8 g / m ² .

Further, in order to prevent the heat transfer layer surface from being rubbed against the heat transfer receiving layer surface or the heat-sensitive recording layer surface to thereby generate color stain on the heat transfer receiving layer surface or the heat-sensitive recording layer surface, 0.1 to 0. A protective layer of about 8 g / m ² can be provided. Such a protective layer is formed, for example, by applying a protective layer coating liquid mainly composed of an ultraviolet curable compound such as an acrylic monomer or a prepolymer onto the thermal transfer layer, and then irradiating with ultraviolet rays.

In the protective layer coating solution, benzoin, benzopheno, 2,2-diethoxyacetophenone, p-
A polymerization initiator such as dimethylaminoacetophenone is added, and further, a thermofusible organic compound, an inorganic pigment, an organic pigment, and the like contained in the thermal transfer layer can be added to the protective layer.

It is possible to use two or more middle leaf recording sheets, or to further contain a leuco dye in the thermal transfer receiving layer of the lower leaf recording sheet. When two or more middle-leaf recording sheets are used, at least the middle-leaf recording sheet has a heat-sensitive recording layer only on the front surface of the middle-leaf base sheet (the heat transfer layer Is required, a heat transfer receiving layer is provided on the front surface of the middle leaf base sheet, and a heat transfer layer is provided on the back surface (a heat transfer layer is required on the back surface of the upper leaf recording material sheet), and At least two or more materials selected from those having a heat-sensitive recording layer on the front surface of the middle leaf base sheet and a heat transfer layer on the back surface thereof.

As the upper, middle and lower leaf base sheets, 2
Examples include high quality paper, film, and synthetic paper of about 0 to 70 g / m ² , and particularly, for the base sheet of the upper and middle leaves, glassine paper of about ²⁰ to 45 g / m ² is preferable. A recording portion having a high recording density can be obtained.

Further, in the heat-sensitive recording medium of the present invention, in order to improve the recording sensitivity, a pigment having an oil absorption of about 70 to 300 ml / 100 g or a hollow organic particle is adhered between the lower leaf base sheet and the thermal transfer receiving layer. An undercoat layer containing an agent as a main component can also be provided.

The heat-sensitive multiplex copy sheet of the present invention has a known paper processing technique such as providing an adhesive layer on the back surface of the lower leaf recording sheet, printing each layer with UV ink, or providing a magnetic recording layer. Can be added.

[0037]

EXAMPLES The present invention will be described below in more detail with reference to Examples, but it should be understood that the present invention is by no means restricted thereto. Unless otherwise specified, parts and% in the examples are parts by weight and% by weight, respectively.

[Preparation of Solution A] 10 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluoran, sulfone-modified polyvinyl alcohol (trade name: Goselan L-
3266, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), a composition comprising 5 parts of a 10% aqueous solution and 25 parts of water was pulverized with a sand mill until the average particle diameter became 0.8 μm to obtain a liquid A.

[Preparation of Solution B] 10 parts of 2,4'-dihydroxydiphenylsulfone (melting point: 183 ° C.), sulfone-modified polyvinyl alcohol (trade name: Goselan L-326)
6, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), a composition comprising 5 parts of a 10% aqueous solution and 25 parts of water was pulverized with a sand mill to an average particle size of 1.5 μm to obtain a liquid B.

[Preparation of Solution C] A composition consisting of 10 parts of m-terphenyl, 5 parts of a 10% aqueous solution of sulfone-modified polyvinyl alcohol (trade name: Goselan L-3266, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and 25 parts of water. Was pulverized with a sand mill until the average particle diameter became 1.0 μm to obtain a liquid C.

[Preparation of Coating Solution (I) for Thermosensitive Recording Layer] Solution A 50
Parts, 100 parts of solution B, 15 parts of amorphous silica (trade name: Mizukasil P-527, manufactured by Mizusawa Chemical Industry Co., Ltd.), 10 parts of light calcium carbonate, acrylic latex having an average molecular weight of 8,000,000 to 10,000,000 (trade name: Polysol) AM2250,
Solid content 50%, Showa Polymer Co., Ltd.) 20 parts, melting point 75 ° C
5 parts of an aqueous dispersion of paraffin wax (solid concentration 30%, average particle diameter 0.5 μm), 10 parts of an aqueous dispersion of zinc stearate (solid concentration 30%, average particle diameter 0.8 μm) and 30 parts of water Is mixed and agitated to form a coating solution (I) for the heat-sensitive recording layer.
I got

[Preparation of Coating Solution (II) for Thermosensitive Recording Layer] Solution A 4
0 parts, 80 parts of liquid B, 40 parts of liquid C, 25 parts by weight of amorphous silica (trade name: Mizukasil P-527, manufactured by Mizusawa Chemical Industry Co., Ltd.), carboxy-modified polyvinyl alcohol (trade name:
KL-318, manufactured by Kuraray Co., Ltd.)
2 parts of a 20% aqueous solution of glyoxal and 30 parts of water were mixed and stirred to obtain a coating liquid (II) for a heat-sensitive recording layer.

[Preparation of coating liquid (I) for thermal transfer layer] 10 parts of 3-piperidino-6-methyl-7-anilinofluoran,
50 parts of carnauba wax and stearamide 2
0 part was mixed and melted at 100 to 120 ° C. to obtain a thermal transfer layer layer coating liquid (I).

[Preparation of Coating Solution (II) for Thermal Transfer Layer] 3-Piperidino-6-methyl-7-anilinofluoran 10
, 40 parts of behenic acid, 30 parts of montan wax and 20 parts of paraffin wax were mixed and melted at 100 to 120 ° C to obtain a thermal transfer layer layer coating liquid (II).

[Preparation of Coating Solution for Thermal Transfer Receiving Layer] 65 parts of aluminum hydroxide (average particle size: 1 μm), 20 parts of zinc oxide (average particle size: 0.5 μm), 3,5-di (α-methylbenzyl) salicylic acid 25 parts of a 30% aqueous dispersion of a mixed melt of zinc and α-methylstyrene / styrene copolymer (mixed melt weight ratio = 80/20, average particle diameter 2.3 μm), mono (or bis or tris or tetrakis) ) [Poly (0-4)
[Ω-hydro [poly (1-7) α-methylbenz] -α
-Yl] benzyl] 25 parts of a 30% aqueous dispersion of a zinc salt of salicylic acid-styrene copolymer which is a zinc salt of 2-hydroxybenzoic acid, and 1 part of a carboxy-modified polyvinyl alcohol
50 parts of a 0% aqueous solution, 10 parts of a 20% aqueous solution of a polyamide epichlorohydrin resin as a waterproofing agent, and a glass transition point of 2
Styrene-butadiene latex (solid concentration 50
%), A composition comprising 5 parts of a 20% aqueous solution of sodium polyacrylate and 100 parts of water was mixed and stirred to obtain a coating liquid for a thermal transfer receiving layer.

[Preparation of coating liquid for undercoat layer] Oil absorption is 80 m
1/100 g calcined kaolin (average particle size 1.8 μm)
50 parts, hollow particles (average outer diameter 1 μm, average inner diameter 0.7 μm
m, membrane material polystyrene, solid content concentration 50%) latex 100 parts, 10% aqueous solution of polyvinyl alcohol 60
Parts, styrene-butadiene latex (solid concentration 50
%) A composition consisting of 12 parts and 100 parts of water was mixed and stirred to obtain a coating liquid for an undercoat layer.

Example 1 Preparation of Upper Leaf Recording Sheet On the front side of an upper leaf base sheet (glassine paper containing a basis weight of 36 g / m ² , a tension of 1.0 and 8% by weight of talc), a coating liquid for heat-sensitive recording was applied. After coating and drying (I) so that the coating amount after drying is 4.0 g / m ² , a super calender treatment is performed to provide a heat-sensitive recording layer, and the back surface (back surface side) of 120 to 1
The heat transfer layer coating liquid (I) heated to 30 ° C. was 6.0 g /
After application of m ² , the resultant was cooled to form a thermal transfer layer to obtain an upper leaf recording sheet.

Preparation of middle leaf recording sheet Front side (front side) of a middle leaf base sheet (crusin paper containing 36 g / m ² of rice, 1.0 in tension, and 8% by weight of talc)
The coating amount after drying the heat-sensitive recording layer coating liquid (II) is 5.
After coating and drying to provide 0 g / m ² to provide a heat-sensitive recording layer, a super calender treatment was performed, and a heat transfer layer coating liquid (II) heated to 120 to 130 ° C. was applied to the back surface (back surface side). After coating at 6 g / m ² , the resultant was cooled to form a thermal transfer layer to obtain a midleaf recording sheet.

Preparation of lower leaf recording sheet A lower layer base sheet (neutral high-quality paper containing a basis weight of 64 g / m ² , a tension of 0.8, and 5% by weight of calcium carbonate) was coated with an undercoat layer. after the liquid and thermal transfer receiving layer coating solution coating amount after drying was respectively 9.2 g / m ^2, sequentially applied and dried to the undercoat layer and the thermal transfer receiving layer so that 5.1 g / m ² provided a thermal transfer A lower calender recording sheet was obtained by performing a super calender treatment so that the density of the receiving layer was 1.1 g / cm ³ . After forming the undercoat layer, a super calender treatment was performed.

Preparation of Thermally Sensitive Multiplexed Copy Sheet The back side of the upper leaf recording sheet and the front side of the middle leaf recording sheet, and the back side of the middle leaf recording sheet and the front side of the lower leaf recording sheet are cut so as to be in contact with each other. The sheets were stacked to obtain a thermosensitive multiple copy sheet.

Example 2 In the preparation of the middle leaf recording sheet of Example 1, the coating amount after drying was changed to 5.5 m ² using the coating solution for the thermal transfer receiving layer instead of the coating solution (II) for the heat-sensitive recording layer. A heat-sensitive multiple copy sheet was obtained in the same manner as in Example 1 except that the thermal transfer receiving layer was formed by coating and drying as described above.

Example 3 A heat-sensitive multiple copy sheet was obtained in the same manner as in Example 1 except that the thermal transfer layer was not provided in the production of the upper leaf recording sheet of Example 1.

Example 4 The procedure of Example 1 was repeated except that 4,4′-dihydroxydiphenyl sulfone (melting point: 248 ° C.) was used instead of 2,4′-dihydroxydiphenyl sulfone (melting point: 183 ° C.). In the same manner, a thermosensitive multiple copy sheet was obtained.

Example 5 In the preparation of solution B, bis (3-allyl-4-hydroxyphenyl) sulfone (melting point 151 ° C.) was used instead of 2,4′-dihydroxydiphenyl sulfone (melting point 183 ° C.).
A thermosensitive multiple copy sheet was obtained in the same manner as in Example 1 except for using.

Example 6 In the preparation of solution B, 4,4′-dihydroxydiphenyl sulfone (melting point: 183 ° C.) was replaced by 4,4′-dihydroxysulfonate (melting point: 183 ° C.).
Dihydroxydiphenyl sulfone (melting point 248 ° C) 5
And a color former containing 2,2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] diethyl ether as a main component [trade name: D-90, manufactured by Nippon Soda Co., Ltd.] 5
A heat-sensitive multiplex copy sheet was obtained in the same manner as in Example 1 except that parts were used.

Example 7 In the preparation of solution B, 2,4'-dihydroxydiphenyl sulfone (melting point: 183 ° C) was replaced by 2,4'-dihydroxysulfone (melting point: 183 ° C).
Dihydroxydiphenyl sulfone (melting point 183 ° C) 2
And a heat-sensitive multiple copy sheet was obtained in the same manner as in Example 1 except for using 4 parts by weight and 8 parts of 4,4'-isopropylidene diphenol (melting point: 156 ° C.).

Example 8 A heat-sensitive multiplex copy sheet was obtained in the same manner as in Example 1, except that in preparing the coating solution (I) for the thermosensitive recording layer, 160 parts of the B solution was used instead of 100 parts of the B solution. Was.

Example 9 A heat-sensitive multiplex copy sheet was obtained in the same manner as in Example 1, except that 20 parts of the solution B was used instead of 100 parts of the solution B in the preparation of the coating solution (I) for the heat-sensitive recording layer. Was.

COMPARATIVE EXAMPLE 1 In the preparation of solution B, 4-hydroxy-butane was used instead of 2,4'-dihydroxydiphenylsulfone (melting point: 183 ° C.)
4'-isopropoxydiphenyl sulfone (melting point 128
C) except that the heat-sensitive multiple copy sheet was obtained in the same manner as in Example 1.

Comparative Example 2 Example 1 was repeated except that 4,4′-cyclohexylidenediphenol (melting point: 175 ° C.) was used instead of 2,4′-dihydroxydiphenyl sulfone (melting point: 183 ° C.) in the preparation of Liquid B. In the same manner as in the above, a heat-sensitive multiple copy sheet was obtained.

Comparative Example 3 In the preparation of the coating liquid (I) for the heat-sensitive recording layer, instead of 20 parts of an acrylic latex (solid concentration: 50%) having an average molecular weight of 8 to 10 million, an acrylic having an average molecular weight of 280,000 was used. A heat-sensitive multiple copy sheet was obtained in the same manner as in Example 1 except that 20 parts of a system latex (solid concentration: 50%) was used.

The following evaluation test was conducted on the thus obtained heat-sensitive multiplex copy sheet, and the obtained results are shown in Table 1.

[Heat Sensitive Recording Density] Thermal Sensitivity Evaluation Machine [Product Name: Thermal Printer PW-PR01-02, manufactured by NEC Corporation]
, Recording in the maximum applied energy mode, and measuring the density of each recording portion with a Macbeth densitometer (trade name: RD914 type,
Macbeth)).

[Recording Image Quality] The recording image quality of the recording portion of the upper leaf recording sheet was visually determined as follows. A: There is no white spot in the recording section. ：: There is a little white spot in the recording part. X: There are many white spots in the recording portion.

[Recording Runnability] Sticking that occurs during recording in the above evaluation of the thermosensitive recording density was determined as follows. A: No sticking mark is observed in the recording section. ：: Some traces of sticking are seen in the recording section. X: Sticking marks are strongly observed in the recording portion.

[0066]

[Table 1]

[0067]

As shown in Table 1, the heat-sensitive multiplex copy sheet of the present invention has a high recording density on each recording sheet, and furthermore, the image quality and the recording runnability of the recording section of the heat-sensitive recording layer of the upper leaf recording sheet. It has excellent effects.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H026 AA07 AA28 BB01 BB24 BB30 DD34 DD48 DD53 EE03 FF01 FF27 GG01 2H111 AA03 AA26 AA33 AA49 BA03 BA08 BA09 BA12 BA52 BA53 BA54 BB04 CA03 CA30 CA33

Claims (5)

[Claims] 1. An upper leaf recording sheet having a heat-sensitive recording layer containing a leuco dye, a color former and an adhesive on the front surface of an upper leaf substrate sheet, and a leuco dye on the front surface of a middle leaf substrate sheet. A middle-leaf recording sheet having a heat-sensitive recording layer containing a coloring agent, and a thermal transfer layer containing a leuco dye and a heat-fusible organic compound on the back surface of the base sheet, and a front-side surface of a lower-leaf base sheet. In a thermosensitive multiplex copying sheet in which a lower leaf recording sheet having a thermal transfer receiving layer containing a colorant and an adhesive is sequentially superimposed so that each front side is facing upward, the lower leaf recording sheet is present in the thermosensitive recording layer of the upper leaf recording sheet. Melting point 150-250 as coloring agent
A heat-sensitive multiplex copying sheet containing a sulfonyl organic compound at a temperature of ℃ and a hydrophobic acrylic resin having an average molecular weight of 5,000,000 or more as an adhesive. 2. A sulfonyl-based organic compound having a melting point of 150 to 250 ° C. is added to the heat-sensitive recording layer of the upper leaf recording sheet in an amount of 1%.
The heat-sensitive multiplex copy sheet according to claim 1, which contains 0 to 40% by weight. 3. A heat transfer layer containing a leuco dye and a heat-fusible organic compound on the back surface of the upper leaf base sheet.
The heat-sensitive multiplex copying sheet according to 1 or 2. 4. The middle leaf recording sheet according to claim 3, further comprising a heat transfer receiving layer containing a colorant and an adhesive on the front surface of the middle leaf base sheet, and a leuco dye and a heat fusible layer on the back surface. The heat-sensitive multiplex copy sheet according to claim 3, which is a middle-leaf recording sheet having a thermal transfer layer containing a hydrophilic organic compound. 5. An upper leaf base sheet and a middle leaf base sheet each having a basis weight of 25 to 40 g / m ² and a tension of 0.9 to 1.
Sensitive multiple copy sheet according to claim 1 is a paper of 3 g / m ^2.