JP2000071614A - Thermosensitive multiple copy sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermosensitive multiple copy sheet having excellent recording density and dot reproducibility on a lower recording sheet and excellent operability. SOLUTION: In the thermosensitive multiple copy sheet comprising at least an upper leaf recording sheet having a thermal recording layer containing a leuco dye and a colorant on one surface of an upper leaf base material sheet and a thermal transfer layer containing a leuco dye and a thermally fusible organic compound on the other surface, and a lower leaf recording sheet having a thermal transfer receiving layer containing a colorant and an adhesive on one surface of a lower leaf base material sheet; as the upper leaf base material sheet, a hollow polyethylene terephthalate film having 25 to 40 g/m2 of weighing and 30 to 100 cc/100 g of a hollow content amount is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material utilizing a color-forming reaction between a leuco dye and a color former, and more particularly to a heat-sensitive multi-copy sheet capable of simultaneously performing heat-sensitive recording on two or more 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, and its recording equipment is compact and easy to maintain, so that it is used not only as a recording medium for facsimile machines and various computers but also in a wide range of fields. In particular, after using thermal recordings as receipts,
There is an increasing demand for a thermosensitive recording medium capable of recording on a number of sheets with a single thermal recording.

In order to obtain clear thermal recording images on a plurality of sheets, a heat-sensitive recording layer containing a leuco dye and a coloring agent is provided on one surface of the upper leaf base sheet, and on the other surface of the upper leaf base sheet, Upper leaf recording sheet provided with a thermal transfer layer containing a leuco dye and a heat-fusible organic compound, and lower leaf recording provided with a thermal transfer receiving layer containing a colorant and an adhesive on one surface of a lower leaf base sheet Thermal multiple copy sheets having at least one sheet are disclosed in JP-A-57-96895 and JP-A-57-968.
No. 96. However, there is a problem in the recording density and dot reproducibility on the lower leaf recording sheet.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat-sensitive multiplex copy sheet which is excellent in recording density and dot reproducibility on a lower leaf recording sheet and excellent in workability.

[0005]

Means for Solving the Problems An upper leaf base sheet has a heat-sensitive recording layer containing a leuco dye and a color former on one surface thereof,
An upper leaf recording sheet having a thermal transfer layer containing a leuco dye and a heat-fusible organic compound on the other side, and a thermal transfer receiving layer containing a colorant and an adhesive provided on one side of a lower leaf base sheet. As a means for solving the above-mentioned problems, the present invention provides an upper-leaf base sheet having a basis weight of 25
４０40 g / m ² and hollow content is 30-100 cc / 1
A hollow polyethylene terephthalate film of 00 g is used.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the support (upper leaf base sheet) of the upper leaf recording sheet in the thermal multiplex recording sheet has a basis weight of 25 to 40 g / m ² and a hollow content of 30 to 10 g / m ² .
0 cc / 100 g of a hollow polyethylene terephthalate film is used, and the upper leaf base sheet has a rice area of less than 25 g / m ² or a hollow content of 1
If it exceeds 00 cc / 100 g, the tensile strength of the base sheet itself will decrease, and the workability in forming the heat-sensitive recording layer and the thermal transfer layer will decrease. Rice tsubo of upper leaf base sheet is 40g
If it exceeds / m ² , the recording sensitivity of the thermal transfer layer of the upper recording sheet decreases, and the recording density of the thermal transfer receiving layer of the lower recording sheet decreases. The hollow content is 30 cc / 100
When the weight is less than g, the image quality of recording on the lower leaf recording sheet may be reduced, or curl may occur after the formation of the heat-sensitive recording layer, resulting in a decrease in workability.

Such a hollow polyethylene terephthalate film is, for example, a fine powder (average particle size of 0.38) incompatible with polyethylene terephthalate resin (density: 1.38).
(About 1 to 5 μm), melt-extruded, and then successively biaxially stretched to form microcavities (about 1 to 10 μm) at the time of stretching. Alternatively, the hollow polyethylene terephthalate film may be formed by firing with a foaming agent.

[0008] Examples of the incompatible fine powder include calcium carbonate, magnesium carbonate, aluminum hydroxide, and titanium oxide. The content of the incompatible fine powder is preferably about 5 to 20% by weight based on the upper leaf sheet.

The hollow content in 100 g of the hollow polyethylene terephthalate film is calculated by the following equation (1). Hollow content = 100 × (1 / D) −Σ (M _i / d _i ) (1) In the formula (1), D is the apparent density of the hollow polyethylene terephthalate film, and the film (10 cm × 10 c
m) divided by its volume (10 cm × 10 cm × thickness cm). M _i is hollow polyethylene terephthalate film weight of the material in 100 g, d _i denotes the density of each material.

In the hollow polyethylene terephthalate film, a stabilizer, an antistatic agent and a dye can be appropriately added. Further, both surfaces of the upper leaf-described sheet may be subjected to corona discharge treatment, anchor coat treatment and antistatic treatment.

The heat-sensitive multiplex recording sheet of the present invention is used in a state where at least the thermal transfer layer of the upper leaf recording sheet and the thermal transfer receiving layer of the lower leaf recording sheet are set in contact with each other. A heat transfer receiving layer containing a colorant and an adhesive is provided on one surface of the middle leaf base sheet between the and the lower leaf recording sheet, and a leuco dye and a heat-fusible organic compound are contained on the other surface. This includes a sheet in which at least one middle sheet recording sheet provided with a thermal transfer layer is set.

As the middle-leaf base sheet, for example, the above-mentioned upper-leaf base sheet, glassine paper, woodfree paper, etc. are used. The basis weight of glassine paper and high quality paper is 20 to 50 g / m
^{About 2} is preferred. In addition, as the lower leaf base sheet, high quality paper, coated paper, film, foamed film, etc., having a basis weight of about 30 to 200 g / m ² can be used.

Examples of the leuco dye contained in the heat-sensitive recording layer and the heat transfer layer include the following.
3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2)
-Methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3-diethylamino-7-dibenzylaminofluoran, 3-cyclohexylamino-6-chlorofluoran, 3-diethylamino-6 -Methyl-7-chlorofluorane, 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-piperidino -6-methyl-7-anilinofluoran, 3,3-bis [1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-2-yl] -4,5,6,7 -Tetrachlorophthalide, 3,3-bis [1- (4-methoxyphenyl) -1
-(4-pyrrolidinophenyl) ethylene-2-yl]-
4,5,6,7-tetrachlorophthalide, 3,6, -bis (dimethylamino) fluorene-9-spiro-3'-
(6′-dimethylamino) phthalide, 3- (N-ethyl-N-2-tetrahydrofurfurylamino) -6-methyl-7-anilinofluoran, 3- (4-dimethylamino) anilino-5,7 -Dimethyl fluoran, etc.

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.

Examples of colorants contained in the heat-sensitive recording layer and the heat transfer receiving layer include the following compounds.
Acid clay, activated clay, attapulgite, zeolite,
Acidic clays such as bentonite, 4,4'-isopropylidene diphenol, bis (2-tert-butylphenol), 4,4'-sec-butylidene diphenol, 4-
Phenylphenol, 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'-methyldiphenylsulfone, 4-hydroxy-4'-benzyloxydiphenylsulfone, 3,4- Dihydroxyphenyl-4 '
-Methylphenyl sulfone, hydroquinone monobenzyl ether, 4-hydroxybenzophenone, 1,1-bis (4-hydroxyphenyl) -1-phenylethane,
1,4-bis [(4-hydroxyphenyl) isopropylidene] benzene, benzyl 4-hydroxybenzoate,
4-hydroxybenzoic acid-p-methoxybenzyl, a phenolic compound such as a novolak type phenol resin, a phenol polymer, 4- [2- (p-methoxyphenoxy)
Ethyloxy] zinc salicylate, 4- [3- (p-tolylsulfonyl) propyloxy] zinc salicylate, 5-
[P- (2-p-methoxyphenoxyethoxy) cumyl] zinc salicylate, zinc 4-octyloxyacetylaminosalicylate, mono (or bis or tris or tetrakis) [poly (0-4) [ω-hydro [poly (1 ~ 7) α-methylbenz] -α-yl] benzyl]
Zinc salts of salicylic acid derivatives such as zinc salicylate and 3,5-di (α-methylbenzyl) zinc salicylate, Np-
Compounds having a sulfamide bond in the molecule, such as tolylsulfonyl-N'-phenylurea and 4,4'-bis (p-tolylsulfonylaminocarbonylamino) diphenylmethane. Of course, the compounds are not limited to these, If necessary, two or more of them can be used in combination. The amount of the coloring agent used is about 10 to 50% by weight based on the total solids content of the heat-sensitive recording layer in the heat-sensitive recording layer, and 10 to 70% by weight in the thermal transfer receiving layer based on the total solids content of the thermal transfer receiving layer. %. Of these, a zinc salt of a salicylic acid derivative is preferred for the thermal transfer receiving layer because it is particularly excellent in heat-sensitive recording properties and pressure-sensitive recording properties.

Of course, it is not limited to these,
If necessary, two or more kinds can be used in combination. The amount of the coloring agent used is about 10 to 70% by weight based on the total solids of the heat-sensitive recording layer in the heat-sensitive recording layer, and 1 to 70% by weight based on the total solids in the heat-transfer receiving layer.
It is about 0 to 60% by weight.

The heat-fusible organic compound contained in the thermal transfer layer 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, stearic acid, behenic acid, stearic acid amide, ethylenebisstearic acid amide, methyl stearate,
Higher aliphatic compounds such as stearic acid anilide are preferred because of their excellent pressure-sensitive recording properties. 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.

In the heat-sensitive recording layer, pigments such as kaolin, calcium carbonate, amorphous silica, titanium oxide, aluminum hydroxide, calcined kaolin, zinc oxide, m-terphenyl, di-p-oxalate may be used, if necessary, as auxiliaries. -Methylbenzyl ester, di-p-chlorobenzyl oxalate, dibenzyl terephthalate, phenyl 1-hydroxynaphthoate, 1,2-di- (3-methylphenoxy) ethane, 1,2-diphenoxyethane ,
Sensitizers such as 1-phenoxy-2-naphthoxyethane and p-benzylbiphenyl, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,1,3-tris (2 -Methyl-4-hydroxy-5-tert-butylphenyl) butane, N, N'-di-2-naphthyl-p-phenylenediamine, 2,2'-
Preservative improvers such as sodium methylenebis (4,6-di-tertbutylphenyl) phosphate, waxes such as carnauba wax, montan wax, paraffin wax, microcrystalline wax, polyethylene wax, stearic acid amide, ethylene bisstearic acid amide And other lubricants such as higher aliphatic amides, zinc stearate, calcium stearate, etc .; and fluorescent dyes, coloring dyes, surfactants, and water-proofing agents.

The heat-sensitive recording layer is generally made of water as a medium, a leuco dye finely dispersed to have an average particle diameter of about 0.1 to 3 μm, a coloring agent, an adhesive, and if necessary, a sensitizer and a storage stability improving agent. The coating liquid for the heat-sensitive recording layer obtained by mixing and stirring is dried on one surface of a specific paper (upper leaf base sheet) and then dried by application so that the coating amount is about ² to 7 g / m ^2. Is done.

The thermal transfer receiving layer is obtained by mixing and stirring a colorant and an adhesive, 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 coating liquid for application is formed on one surface of the lower leaf base sheet or the middle leaf base sheet by applying and drying such that the applied amount after drying is about 1 to 7 g / m ² . As the adhesive contained in the thermal transfer receiving layer, an adhesive that 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.

Examples of the method of applying the coating solution for the heat-sensitive recording layer and the coating solution for the thermal transfer receiving layer include an air knife system, a Meyer bar system, a pure blade, a system rod blade system, a reverse roll system, a gravure system, and a slit die system. Is mentioned.

The thermal transfer layer is generally formed by applying a thermal transfer coating solution in which a leuco dye is added to a heat-soluble heat-soluble organic compound on the other surface of the upper leaf or middle leaf base sheet at 1 to 8 g / m ^2.
For example, it is formed by applying by a hot melt method so as to have a degree.

[0023]

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.

Embodiment 1

(1) 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, Nippon Synthetic Chemical Industry Co., Ltd.) A) was prepared by pulverizing a composition comprising 5 parts of a 10% aqueous solution and 25 parts of water using a sand mill until the average particle diameter became 0.8 μm.

(2) Preparation of Solution B 10 parts of 4-hydroxy-4'-isopropoxydiphenylsulfone, 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 of water and 25 parts of water was pulverized with a sand mill until the average particle diameter became 1.5 μm to obtain a liquid B.

(3) Preparation of Solution C A composition comprising 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. The product was pulverized with a sand mill until the average particle diameter became 1.0 μm to obtain a liquid C.

(4) Preparation of coating solution for heat-sensitive recording layer 40 parts of liquid A, 80 parts of liquid B, 40 parts of liquid C, 15 parts by weight of amorphous silica (trade name: Mizuka Seal P-527, manufactured by Mizusawa Chemical Industry Co., Ltd.) 10% aqueous solution 1 of completely saponified polyvinyl alcohol (trade name: PVA-105, manufactured by Kuraray Co., Ltd.)
00 parts, 2 parts of a 20% aqueous solution of glyoxal and 3 parts of water
And 0 parts were mixed and stirred to obtain a coating solution for a heat-sensitive recording layer.

(5) Preparation of Coating Liquid for Thermal Transfer Ten parts of 3-piperidino-6-methyl-7-anilinofluoran, 30 parts of carbana wax and 15 parts of stearamide were melted at 120 to 130 ° C. and thermally transferred. A layer coating liquid was obtained.

(6) Preparation of coating solution for thermal transfer receiving layer 65 parts of aluminum hydroxide, 20 parts of zinc oxide, mono (or bis or tri or tetrakis) [poly (0-4)
[Ω-hydro [poly (1-7) α-methylbenz] -α
-Yl] benzyl] 50 parts of a 30% aqueous dispersion of zinc salt of salicylic acid-styrene copolymer which is a zinc salt of 2-hydroxybenzoic acid, and 1 part of carboxy-modified polyvinyl alcohol
50% by weight of a 0% aqueous solution, 10 parts of a 20% aqueous solution of a polyamide epichlorohydrin resin as a waterproofing agent, and a styrene-butadiene resin having a glass transition point of 2 ° C.
%), 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.

(7) Preparation of Coating Solution for Protective Layer 100 parts of a 10% aqueous solution of acetoacetyl-modified polyvinyl alcohol, 50% of kaolin having an average particle diameter of 0.8 μm
A composition comprising 40 parts of the dispersion and 1 part of a 30% zinc stearate dispersion was mixed and stirred to obtain a coating liquid for a protective layer.

(8) Preparation of Upper Leaf Recording Sheet One side of a hollow polyethylene terephthalate film (25 g / m ² tsubo, 35 cc / 100 g hollow content, containing 10% by weight of aluminum hydroxide having an average particle diameter of 1 μm) The coating amount after drying the heat-sensitive recording coating liquid and the protective layer coating liquid is 4.0 g / m ² and 2.5 g / m ² on the front side).
After forming a heat-sensitive recording layer and a protective layer by coating and drying in order to obtain ² , a super calender treatment was performed, and a coating liquid for a thermal transfer layer having a temperature of 70 to 80 ° C. was applied to the other surface (back side). After coating at 2 g / m ² , cooling was performed to form a thermal transfer layer to obtain an upper leaf recording sheet.

(9) Preparation of middle leaf recording sheet A coating liquid for a heat transfer receiving layer was dried on one surface (front surface side) of a hollow polyethylene terephthalate film having a square meter of 25 g / m ² and a hollow content of 35 cc / 100 g. After coating and drying so that the coating amount is 4.0 g / m ² , a super calender treatment is performed to provide a thermal transfer receiving layer, and the other side (back side) is coated with a thermal transfer layer at a temperature of 70 to 80 ° C. After applying 3.2 g / m ^{2 of the} solution, the solution was cooled to form a thermal transfer layer to obtain a midleaf recording sheet.

(10) Preparation of lower leaf recording sheet Neutral high-quality paper having a basis weight of 64 g / m ² (lower leaf base sheet)
On one surface (surface side) of the above, a coating solution for a thermal transfer receiving layer was applied and dried so that the coating amount after drying was 5.0 g / m ² to form a thermal transfer receiving layer, and then subjected to a super calender treatment. To obtain a lower leaf recording sheet.

(11) Preparation of heat-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 cut to A4 size. The sheets were stacked so as to be in contact with each other to obtain a thermosensitive multiple copy sheet.

Example 2 In the production of the upper leaf recording sheet and the middle leaf recording sheet of Example 1, the rice tsubo was 25 g / m ² and the hollow content was 35 cc / 1.
Instead of 00 g of a hollow polyethylene terephthalate film (containing 10% by weight of aluminum hydroxide having an average particle diameter of 1 μm), 25 g / m ² of rice tsubo and a hollow content of 80 cc
/ 100 g of a hollow polyethylene terephthalate film (containing 10% by weight of calcium carbonate having an average particle diameter of 1 μm) was used in the same manner as in Example 1 to obtain a thermosensitive multiplex copying sheet.

Example 3 In the preparation of the upper leaf recording sheet and the middle leaf recording sheet of Example 1, a rice tsubo was 25 g / m ² and the hollow content was 35 cc / 1.
Instead of 00 g of a hollow polyethylene terephthalate film (containing 10% by weight of aluminum hydroxide having an average particle diameter of 1 μm), the area is 38 g / m ² and the hollow content is 35 cc.
/ 100 g of a hollow polyethylene terephthalate film (containing 10% by weight of titanium oxide having an average particle diameter of 1 μm) was used in the same manner as in Example 1 to obtain a thermosensitive multiple copy sheet.

Comparative Example 1 In the production of the upper leaf recording sheet and the middle leaf recording sheet of Example 1, 25 g / m ^{2 of} rice and 35 cc / 1 of hollow content.
Instead of 00 g of a hollow polyethylene terephthalate film (containing 10% by weight of aluminum hydroxide having an average particle size of 1 μm), 25 g / m ² of rice tsubo and a hollow content of 20 cc
/ 100 g of hollow polyethylene terephthalate film (10% by weight of aluminum hydroxide having an average particle size of 1 μm)
(Contained), a heat-sensitive multiple copy sheet was obtained in the same manner as in Example 1.

Comparative Example 2 In the preparation of the upper leaf recording sheet and the middle leaf recording sheet of Example 1, the rice tsubo was 25 g / m ² and the hollow content was 35 cc / 1.
Instead of 00 g of a hollow polyethylene terephthalate film (containing 10% by weight of aluminum hydroxide having an average particle diameter of 1 μm), 45 g / m ² of rice tsubo and a hollow content of 40 cc
/ 100 g of hollow polyethylene terephthalate film (10% by weight of aluminum hydroxide having an average particle size of 1 μm)
(Contained), a heat-sensitive multiple copy sheet was obtained in the same manner as in Example 1.

COMPARATIVE EXAMPLE 3 In the production of the upper leaf recording sheet and the middle leaf recording sheet of Example 1, the rice tsubo was 25 g / m ² and the hollow content was 35 cc / 1.
Instead of 00 g of a hollow polyethylene terephthalate film (containing 10% by weight of aluminum hydroxide having an average particle diameter of 1 μm), the area is 30 g / m ² and the hollow content is 110 c.
A heat-sensitive multiple copy sheet was obtained in the same manner as in Example 1 except that c / 100 g of a hollow polyethylene terephthalate film (containing 10% by weight of aluminum hydroxide having an average particle diameter of 1 μm) was used.

COMPARATIVE EXAMPLE 4 In the production of the upper leaf recording sheet and the middle leaf recording sheet of Example 1, the rice tsubo was 25 g / m ² and the hollow content was 35 cc / 1.
The same procedure as in Example 1 was carried out except that instead of 00 g of the hollow polyethylene terephthalate film (containing 10% by weight of aluminum hydroxide having an average particle diameter of 1 μm), glassine paper having a density of 0.97 and a rice area of 25 g / m ² was used. Thus, a heat-sensitive multiple copy sheet was obtained.

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

[Recording Density and Dot Reproducibility] Using a thermal evaluation machine (trade name: TH-PMD, manufactured by Okura Electric Co., Ltd.), recording each thermal multiple copy sheet with an applied energy of 0.45 mJ / dot, and recording the thermal recording The recording density of the image recorded on the thermal transfer receiving layer of the layer and the lower leaf recording sheet was measured in visual mode with a Macbeth densitometer (RD-914, manufactured by Macbeth), and the recording sensitivity was determined from the measured values. Was.
Regarding the recording image quality, the reproducibility of dots of the thermal head of the recorded image recorded on the thermal transfer receiving layer of the lower leaf recording sheet was visually determined and examined as follows. (Judgment Criteria) A: The dot reproducibility is very excellent. ：: dot reproducibility is excellent. Δ: Reproducibility of dots is slightly poor. X: Poor dot reproducibility.

[Workability] The workability in forming the heat-sensitive recording layer by coating and drying the coating solution for the heat-sensitive recording layer on the upper leaf base sheet was determined as follows. (Judgment Criteria) ：: After coating and drying, curling is small and workability is excellent. Δ: After application drying, curling slightly occurred, and workability was slightly inferior. ×: After coating and drying, curl is strongly generated and workability is poor.

[0045]

[Table 1]

[0046]

The multiple thermographic sheet of the present invention has excellent recording sensitivity and recording image quality and excellent operability.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H026 AA07 BB01 BB21 EE05 FF17 FF27 FF29 2H111 AA03 AA27 BA52 BB06 CA03 CA12 CA34

Claims (1)

[Claims] An upper leaf base sheet has a heat-sensitive recording layer containing a leuco dye and a coloring agent on one side and a thermal transfer layer containing a leuco dye and a heat-fusible organic compound on the other side. An upper leaf recording sheet, and a thermosensitive multiplex copy sheet having at least a lower leaf recording sheet provided with a thermal transfer receiving layer containing a colorant and an adhesive on one surface of the lower leaf substrate sheet, wherein the upper leaf substrate sheet has a grammage of 25~40g / m ^2, heat-sensitive multiple copying, characterized in that a hollow polyethylene terephthalate film of the hollow content 30~100cc / 100g sheet - and.