JPH11301109A - Thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a thermal recording material not being liable to strike- through, and being effective to forgery prevention as well. SOLUTION: A thermal recording material is furnished with a thermal recording layer coloring through heat on at least one surface of a support having an opacity of 70% or more, a backcoat on another surface, and an adhesive layer on the backcoat layer, wherein one kind of a coloring pigment or dye is contained in at least the backcoat layer or adhesive layer. In order to color the backcoat layer or adhesive layer, a coloring pigment or dye marketed generally can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material for labels.

[0002]

2. Description of the Related Art A thermosensitive recording material generally comprises, as a main component, an electron-donating, usually colorless or pale-colored dye precursor and an electron-accepting developer on a support such as paper, synthetic paper, or plastic film. It has a heat-sensitive recording layer,
By heating with a hot pen, laser light, or the like, the dye precursor and the color developer react instantaneously to obtain a recorded image. Japanese Patent Publication Nos. 43-4160 and 45-14039.
No., for example. The heat-sensitive recording material has advantages such as simplicity of equipment, easy maintenance, and no generation of noise, and is used for facsimile paper, automatic ticket vending machines, recording paper for measuring instruments, and POS (point of point).
sales) Widely used for labels, plotters, and various other printer papers. In particular, in recent years, the use of POS labels has been increasing in accordance with the reform of the distribution organization, and further expansion of the use in this field is expected in the future.

A heat-sensitive recording material for a label is characterized in that a heat-sensitive recording layer can be provided on one side of a support and an adhesive layer can be provided on the other side and adhered to an adherend. Is supplied in a state of being stuck.

[0004] In some cases, thermal recording materials for labels are used by attaching them to a plastic film containing a plasticizer at a retail store or the like, in which case the plasticizer penetrates from the back surface and discoloration of the thermal recording image occurs. There is. Further, an emulsifier or the like contained in the pressure-sensitive adhesive may penetrate from the back surface, causing fading of the heat-sensitive recorded image, and these improvements have been strongly desired.

In order to solve such a problem, Japanese Utility Model Application Publication No.
JP-A-140461 proposes a method of providing a back coat layer mainly composed of a water-soluble polymer between a support and an adhesive layer. JP-A-6-227119 discloses a method of providing a back coat layer containing a soap-free type acrylic emulsion, and JP-A-6-23919 discloses a method comprising a two-layer acrylate copolymer as a main component. A method for providing a back coat layer is disclosed.

In general, a thermosensitive recording material for a label is mainly used at a store to display information such as the content, price, and bar code of a product by attaching it to a product or a package of the product. Printing or the like applied to a product or its package may be seen through (through through) the thermosensitive recording material for use, and it often overlaps with label information and is difficult to read.

Further, since the heat-sensitive recording material itself for labels is generally easily available, it has a drawback that it can be easily forged. If the thermosensitive recording material for labels is forged, the price of the product may be changed illegally, and if a fake product is attached with a fake label, the fake product may be distributed to the market. Had been requested.

In Japanese Utility Model Laid-Open No. 4-107076,
A method is disclosed in which a thermosensitive coloring layer is provided on the surface of a transparent support, a colored adhesive layer is provided on the back surface, and a thermosensitive label of any color is obtained. Japanese Patent Application Laid-Open No. Hei 7-156541 discloses a method in which a thermosensitive coloring layer is provided on the surface of a transparent support, a colored layer is provided on the back surface, and a thermosensitive recording material is obtained in which the base is colored.

All of them are characterized by using a transparent support and the colored layer on the back surface can be clearly recognized from the table, which is clearly different from the present invention.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermosensitive recording material for labels which is hard to strike through and is effective in preventing forgery.

[0011]

According to the heat-sensitive recording material of the present invention, a heat-sensitive recording layer which develops color by heating is provided on one side of a support having an opacity of 70% or more, and a back coat layer is provided on the other side. In a heat-sensitive recording material having an adhesive layer provided on the back coat layer, by coloring the back coat layer or the adhesive layer, a heat-sensitive recording material which is difficult to strike through and is also effective in preventing forgery is obtained. I was able to.

The back coat layer or the adhesive layer of the heat-sensitive recording material of the present invention is arbitrarily colored using a coloring pigment or a dye. However, it is clear that the coloring is clearly recognized from the table. There is no hindrance to reading recorded information. Except for white and transparent, the colors can be freely used such as black, red, dark blue, blue, green, and orange as needed.

Further, the thermosensitive recording material of the present invention has a colored back coat layer or a colored adhesive layer, and is therefore very difficult to forge. This is because it is very difficult to color only the back surface of a commercially available thermal recording material for labels.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In producing the heat-sensitive recording material of the present invention, a commercially available coloring pigment or dye can be used for coloring the back coat layer or the adhesive layer. Examples include iron black, carbon black, yellow iron oxide, graphite, cadmium yellow, fast yellow, disazo yellow, molybdate orange, pyrazolone orange, red iron, cadmium red, lake red C, brilliant carmine 6B, quinacridone red, and manganese. Various pigments such as violet, methyl violet, dioxazine violet, ultramarine, navy blue, cobalt blue, Victoria blue lake, phthalocyanine blue, phthalocyanine green, chrome green, zinc green chromium oxide, thioindib, dioxazine, insoluble azo pigment, soluble azo pigment, Indigo dye, azomethine dye, diphenylmethane dye, triphenylmethane dye,
There are various dyes such as anthraquinone dye.

Particularly, a phthalocyanine pigment is preferable in terms of coloring power, and a pigment containing a divalent metal such as copper or iron and having chlorine, bromine, iodine or the like introduced into an aromatic ring can be used.

The amount of the coloring pigment or dye added is not particularly limited as long as it is an amount that can obtain appropriate coloring, but the amount contained in the back coat layer or the adhesive layer is preferably 0.0
Preferably ^{01~1g / m 2, 0.01~0.2g / m} 2 is more preferable.

The color pigment added to the back coat layer or the adhesive layer preferably has a particle size of 10 μm or less, more preferably 5 μm or less. If the particle size is too large, it can be used after being pulverized dry or, if necessary, wet in the presence of a dispersant. There is no lower limit on the particle size.

The back coat layer of the heat-sensitive recording material of the present invention is mainly composed of a water-soluble polymer or an aqueous polymer such as an aqueous emulsion. Examples thereof include an acrylic emulsion, polyvinyl alcohol, modified polyvinyl alcohol, and poly (vinyl alcohol). Sodium acrylate, acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid terpolymer, alkali salt of styrene / maleic anhydride copolymer, ethylene /
Alkaline salts of maleic anhydride copolymers, starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl acetate, polyurethane, polyacrylate, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, Examples include a methyl acrylate / butadiene copolymer and an ethylene / vinyl acetate copolymer.

For the purpose of improving water resistance, a crosslinking agent such as borax, melamine formalin compound, glyoxal, polyaldehyde, epoxy-containing compound, dimethylol urea compound, blocked isocyanate compound, zirconium ammonium carbonate or the like is used in the back coat layer. Can be added. These crosslinking agents can be added in a weight ratio of 0.5 to 20% based on the solid content of the back coat layer. Surfactants, defoamers,
Organic pigments, inorganic pigments, conductive agents, and the like can be added as necessary. These additives should be added in a weight ratio of 0.01 to 20% with respect to the solid content of the back coat layer. Can be.

The back coat layer in the present invention can be composed of a plurality of layers. In this case, it is sufficient that at least one layer constituting the back coat layer contains a coloring pigment or dye.

The pressure-sensitive adhesive layer of the heat-sensitive recording material of the present invention contains a pressure-sensitive adhesive as a main component. Examples of the pressure-sensitive adhesive include a synthetic rubber-based emulsion-type pressure-sensitive adhesive, an acrylic emulsion-type pressure-sensitive adhesive, and a natural rubber-based pressure-sensitive adhesive. Solvent-based pressure-sensitive adhesives, acrylic solvent-based pressure-sensitive adhesives, and silicon-based solvent-based pressure-sensitive adhesives are exemplified, and acrylic emulsion-based pressure-sensitive adhesives are particularly preferable.

When coloring the pressure-sensitive adhesive layer, for example, a dye or a color pigment aqueous dispersion is added to an acrylic emulsion-type pressure-sensitive adhesive, and the colored pressure-sensitive adhesive layer coating liquid is obtained by a method such as sufficient stirring. Can be.

The order of application in producing the heat-sensitive recording material of the present invention is not particularly limited. For example, after a heat-sensitive recording layer is provided on a support, a back coat layer is provided on the other surface, and an adhesive layer is further provided. It is possible to produce with
Alternatively, it can be prepared by providing a back coat layer on a support, providing a heat-sensitive recording layer on another surface, and further providing an adhesive layer on the back coat layer.

The adhesive layer may be provided on the back coat layer by directly applying the adhesive layer liquid on the back coat layer and drying it, or by applying the adhesive layer liquid on release paper in advance and drying. And the back coat layer side of the heat-sensitive recording material before the pressure-sensitive adhesive layer is provided.

The heat-sensitive recording layer of the heat-sensitive recording material of the present invention comprises, as main components, an electron-donating, usually colorless or pale-colored dye precursor and an electron-accepting developer, and a dispersion of these with a binder together with a binder. It is formed by coating on top.

Examples of usually colorless or pale color dye precursors include crystal violet lactone, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl) phthalide, 3,3- Bis (2-methyl-1-octyl-3-indolyl) phthalide, 3-
[4-Diethylamino-2-ethoxyphenyl] -3-
(2-methyl-1-octyl-3-indolyl) -4-
Azaphthalide, 3,3-bis (2-methyl-1-octyl-3-indolyl) -4-azaphthalide, 3-cyclohexylamino-6-chlorofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-
5-methyl-7-dibenzylaminofluoran, 3-diethylamino-6-methyl-7-anilinofluoran,
3-piperidino-6-amino-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-propylamino)-
6-methyl-7-anilinofluoran, 3- (N-ethyl-N-cyclohexyl-6-methyl-7-anilinofluoran, 3- (N-methyl-N-cyclohexylamino) -6-methyl- 7-anilinofluoran, 3- [N
-Ethyl-N- (2-methylbutyl) amino] -6-methyl-7-anilinofluoran, 3- [N-ethyl-N
-(4-methylphenyl) amino] -6-methyl-7-
Anilinofluoran, 3-diethylamino-7-[(3
-Trifluoromethyl) phenyl] aminofluoran, 3
-Dibutylamino-7-[(2-chlorophenyl) amino] fluoran, 6'-dibutylamino-2 '-(2-
Fluoroanilino) spiro [phthalide-3,9'-xanthene].

The electron accepting compound is not particularly limited as long as it is an acidic substance generally used for thermosensitive recording paper.

For example, phenol derivatives, aromatic carboxylic acid derivatives, N, N'-diarylthiourea derivatives, etc.
In addition, polyvalent metal salts such as zinc salts of these organic compounds can be used.

Examples are p-phenylphenol, p
-Hydroxyacetophenone, 4-hydroxy-4'-
Methyldiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxy-
4'-benzenesulfonyloxydiphenyl sulfone,
1,1-bis (p-hydroxyphenyl) propane,
1,1-bis (p-hydroxyphenyl) pentane,
1,1-bis (p-hydroxyphenyl) hexane,
1,1-bis (p-hydroxyphenyl) cyclohexane, 2,2-bis (p-hydroxyphenyl) propane, 2,2-bis (p-hydroxyphenyl) hexane, 1,1-bis (p-hydroxyphenyl) -2-ethylhexane, 2,2-bis (3-chloro-4-hydroxyphenyl) propane, 1,1-bis (p-hydroxyphenyl) -1-phenylethane, 1,3-di- [2
-(P-hydroxyphenyl) -2-propyl] benzene, 1,3-di- [2- (3,4-dihydroxyphenyl) -2-propyl] benzene, 1,4-di- [2-
(P-hydroxyphenyl) -2-propyl] benzene, 4,4'-dihydroxydiphenyl ether, 4,
4'-dihydroxydiphenylsulfone, 3,3'-dichloro-4,4'-dihydroxydiphenylsulfone,
3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone, 3,3'-dichloro-4,4'-dihydroxydiphenyl sulfide, methyl 2,2-bis (4-hydroxyphenyl) acetate, 2,2- Butyl bis (4-hydroxyphenyl) acetate, 4,4'-thiobis (2-
t-butyl-5-methylphenol), benzyl p-hydroxybenzoate, chlorobenzyl p-hydroxybenzoate, dimethyl 4-hydroxyphthalate, benzyl gallate, stearyl gallate, salicylanilide, 5-chlorosalicylanilide, salicylic acid , 3,5-di-te
rt-butylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, 4- [2 ′-(4-methoxyphenoxy) ethyloxy] salicylic acid, 4-n-octyloxycarbonylaminosalicylic acid, 4-n-nonyloxycarbonyl Examples thereof include aminosalicylic acid, 4-n-decyloxycarbonylaminosalicylic acid, 4-n-heptyloxycarbonylaminosalicylic acid, and metal salts of these salicylic acid derivatives.

The binder used in the heat-sensitive recording material of the present invention includes gelatin, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose,
Polyvinyl alcohol, copolymers of maleic anhydride and ethylene, styrene, etc., water-soluble acrylic resin, modified polyvinyl alcohol, water-soluble polymers such as polyurethane,
Latexes such as polyacrylate, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer and the like can be mentioned.

The heat-sensitive recording layer contains inorganic or organic pigments such as diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, and urea-formalin resin. Can be added. In order to improve the thermal responsiveness, the heat-sensitive recording layer contains stearic acid amide, 2-
Benzyloxynaphthalene, 4-benzylbiphenyl,
m-terphenyl, dibenzyl oxalate, di (4-methylbenzyl) oxalate, di (4-chlorobenzyl) oxalate, 4,
An organic compound having a melting point of 80 ° C. to 150 ° C., such as 4′-diallyloxydiphenyl sulfone, can be added.

Other thermal recording layers include head wear prevention,
For the purpose of preventing sticking, zinc stearate,
Higher fatty acid metal salts such as calcium stearate, waxes such as paraffin, paraffin oxide, polyethylene, polyethylene oxide, stearamide and caster wax; dispersants such as sodium dioctyl sulfosuccinate; and ultraviolet rays such as benzophenone and benzotriazole An absorbent, an antioxidant such as a hindered phenol compound, a surfactant, a fluorescent pigment, and the like can be added as necessary.

The coating amount of the heat-sensitive recording layer is usually preferably 0.1 to 2.0 g / m ² as the coating amount of the dye precursor.
~1.5g / m ² is more preferable.

The support used in the heat-sensitive recording material of the present invention is not particularly limited as long as the opacity is 70% or more. Examples include paper, woven fabric, nonwoven fabric, plastic film, synthetic paper, or a composite sheet combining these. The opacity of the support is determined by JI
It can be measured by a method according to SP8138.

The heat-sensitive recording material of the present invention may be provided with an overcoat layer in order to improve abrasion resistance and chemical resistance. The overcoat layer can consist of multiple layers. The overcoat layer contains a water-soluble binder, latex or the like as a main component, and the same water-soluble binder or latex as the binder for the heat-sensitive recording layer can be used. Further, a crosslinking agent, an organic or inorganic pigment, an antifoaming agent, a lubricant and the like can be added as required. The dry coating amount is preferably in the range of 0.2 to 5.0 g / m ² .

An undercoat layer may be provided between the heat-sensitive recording layer and the support to improve the thermal response. Undercoat layer is organic, inorganic pigment, hollow particles,
It is mainly composed of a water-based binder such as a water-soluble polymer or latex, and the same organic and inorganic pigments and water-based binder as those used in the heat-sensitive recording layer can be used. The dry coating amount is preferably in the range of 2.0 to 15.0 g / m ² .

[0037]

Next, the present invention will be described in more detail by way of examples. The parts and percentages shown below are based on weight.

Example 1 (A) Preparation of Undercoat Coating Liquid An undercoat coating liquid having the following composition was prepared. Calcined kaolin 100 parts 50% styrene / butadiene latex aqueous dispersion 24 parts Water 200 parts

(B) Preparation of Thermal Sensitive Coating Solution 20 parts of 3- [N-ethyl-N- (4-methylphenyl) amino] -6-methyl-7-anilinofluoran was added to a 2.5% aqueous solution of polyvinyl alcohol 80 And the resulting mixture was pulverized to obtain a dye precursor dispersion. 40 parts of 2,2-bis (p-hydroxyphenyl) propane was pulverized together with 60 parts of a 5% aqueous solution of polyvinyl alcohol to obtain an electron accepting compound dispersion. 40 parts of 2-benzyloxynaphthalene in 5 parts
The mixture was pulverized together with 60 parts of an aqueous solution of polyvinyl alcohol to obtain a sensitizer dispersion. Using each of the above dispersions, a heat-sensitive coating liquid having the following composition was prepared. 20% dye precursor dispersion 40 parts 40% electron acceptor compound dispersion 30 parts 40% sensitizer dispersion 30 parts 20% calcium carbonate aqueous dispersion 50 parts 40% zinc stearate aqueous dispersion 10 parts 10% polyvinyl Alcohol aqueous solution 60 parts Water 40 parts

(C) Preparation of Overcoat Coating Liquid An overcoat coating liquid having the following composition was prepared. 20% acrylic emulsion 100 parts 20% calcium carbonate dispersion 20 parts 40% zinc stearate dispersion 10 parts Water 100 parts

(D) Preparation of Backcoat Coating Solution A backcoat coating solution having the following composition was prepared. 20% acrylic emulsion 100 parts 20% color pigment aqueous dispersion (Dainichi Seika Kogyo TB-1548 Violet) 7 parts Water 93 parts

(E) Preparation of heat-sensitive recording material On one side of base paper (55 g / m ² ) having an opacity of 81%, the undercoat coating solution prepared in (A) was applied in a solid content of 10 g / m 2.
Coated to dryness, coated on the same surface with the heat-sensitive coating liquid prepared in (B) so as to have a solid coating amount of 4 g / m ² , dried and prepared on the same surface in (C) The overcoat solution was applied to a solid content of 3 g / m ² and dried. Further, the uncoated surface was coated with the back coat coating solution prepared in (D) so as to have a solid content of 1 g / m ² , dried and calendered. An acrylic emulsion-type pressure-sensitive adhesive (Sebian A AST467, 63%, manufactured by Daicel Chemical Industries, Ltd.) was applied to the surface coated with the back coat using a doctor blade (75 μm) and dried to obtain a heat-sensitive recording material.

Example 2 A heat-sensitive recording material was prepared in the same manner as in Example 1 except that the following composition was used when preparing the back coat coating solution. 20% acrylic emulsion 100 parts 20% color pigment aqueous dispersion (Dainichi Seika Kogyo TB-1548Violet) 3 parts Water 97 parts

Example 3 As a color pigment aqueous dispersion to be added to the back coat coating liquid, a 20% color pigment aqueous dispersion (TB-
Except for using 536 Blue), a heat-sensitive recording material was produced in the same manner as in Example 1.

Example 4 As a color pigment aqueous dispersion to be added to the back coat coating liquid, a 20% color pigment aqueous dispersion (TB-
516 (Green) was used in the same manner as in Example 1 to prepare a thermosensitive recording material.

Example 5 A heat-sensitive recording material was prepared as follows using the undercoat coating solution, heat-sensitive coating solution, and backcoat coating solution prepared in Example 1. An undercoat coating liquid is applied to one side of a base paper (55 g / m ² ) having an opacity of 81% so as to have a solid content of 10 g / m ² and dried, and a heat-sensitive coating solution is coated on the same surface with a solid content. Effort 4
g / m ² was applied and dried. Further, the back coat coating liquid was applied to the uncoated surface so as to have a solid content of 1 g / m ² , dried, calendered, and provided with an adhesive layer in the same manner as in Example 1. A recording material was obtained.

Example 6 Using the heat-sensitive coating solution, overcoat coating solution and backcoat coating solution prepared in Example 1, a heat-sensitive recording material was prepared as follows. One side of base paper (75 g / m ² ) with opacity of 85% is coated with a heat-sensitive coating liquid at a solid content of 4 g / m ² and dried, and the same surface is coated with an overcoat coating liquid at a solid content. 3g /
m ² and comprising as coating, and dried. Further, the back coat coating liquid was applied to the uncoated surface so as to have a solid content of 1 g / m ² , dried, calendered, and provided with an adhesive layer in the same manner as in Example 1. A recording material was obtained.

Example 7 Using the heat-sensitive coating solution and the backcoating solution prepared in Example 1, a heat-sensitive recording material was produced as follows. Opacity 8
One side of a 5% base paper (75 g / m ² ) was coated with a heat-sensitive coating solution so as to have a solid content of 4 g / m ² and dried. Further, the back coat coating liquid was applied to the uncoated surface so as to have a solid content of 1 g / m ² , dried, calendered, and provided with an adhesive layer in the same manner as in Example 1. A recording material was obtained.

Example 8 A heat-sensitive recording material was prepared as follows using the undercoat coating solution, the heat-sensitive coating solution, and the overcoat coating solution prepared in Example 1. An undercoat coating liquid is applied to one side of a base paper (55 g / m ² ) having an opacity of 81% to a solid content of 10 g / m ² and dried, and a heat-sensitive coating solution is coated on the same surface with a solid content. A coating amount of 4 g / m ² was applied and dried, and the same surface was coated with an overcoat coating liquid at a solid coating amount of 3 g / m ² .
Dried. Further, on the uncoated surface, a backcoat coating solution obtained by mixing 100 parts of a 20% acrylic emulsion and 100 parts of water was applied so as to have a solid content of 1 g / m2, and dried. Calendar processed. Acrylic emulsion type pressure-sensitive adhesive (Sebian A AST467 63%, manufactured by Daicel Chemical Industries) on the surface coated with the back coat
100 parts of a 20% colored pigment aqueous dispersion (TB-1548 Violet manufactured by Dainichi Seika Kogyo Co., Ltd.) is mixed with 0.4 part of an adhesive coating liquid obtained by mixing with a doctor blade (75 μm), dried, and heat-sensitive recording material I got

Example 9 Using the undercoat coating liquid and the heat-sensitive coating liquid prepared in Example 1, a heat-sensitive recording material was produced as follows. An undercoat coating liquid is applied to one side of a base paper (55 g / m ² ) having an opacity of 81% to a solid content of 10 g / m ² and dried.
The same surface was coated with a heat-sensitive coating liquid so as to have a solid content of 4 g / m ² and dried. Further, a back coat layer and an adhesive layer were provided on the uncoated surface in the same manner as in Example 8 to obtain a thermosensitive recording material.

Example 10 Using the heat-sensitive coating solution and the overcoating solution prepared in Example 1, a heat-sensitive recording material was produced as follows. One side of base paper (75 g / m ² ) with opacity of 85% is coated with a heat-sensitive coating liquid at a solid content of 4 g / m ² and dried, and the same surface is coated with an overcoat coating liquid at a solid content. Coating was performed so that the amount was 3 g / m ^2, and the coating was dried. Further, a back coat layer and an adhesive layer were provided on the uncoated surface in the same manner as in Example 8 to obtain a thermosensitive recording material.

Example 11 Using the heat-sensitive coating solution prepared in Example 1, a heat-sensitive recording material was produced as follows. Base paper with 85% opacity (75g /
m ² ) was coated with a heat-sensitive coating solution at a solid content of 4 g / m ² and dried. Example 8 was applied to the surface not further coated.
In the same manner as in the above, a back coat layer and an adhesive layer were provided to obtain a heat-sensitive recording material.

Comparative Example 1 A heat-sensitive recording material was prepared in the same manner as in Example 1 except that the aqueous dispersion of the coloring pigment was not added to the back coat coating liquid.

Comparative Example 2 A heat-sensitive recording material was prepared in the same manner as in Example 5 except that the aqueous dispersion of the coloring pigment was not added to the back coat coating liquid.

Comparative Example 3 A heat-sensitive recording material was prepared in the same manner as in Example 6 except that the aqueous dispersion of the coloring pigment was not added to the back coat coating liquid.

Comparative Example 4 A heat-sensitive recording material was prepared in the same manner as in Example 7 except that the aqueous dispersion of the coloring pigment was not added to the back coat coating liquid.

The above Examples 1 to 11 and Comparative Examples 1 to 4
The heat-sensitive recording material prepared in the above was evaluated by the following evaluation methods, and the results are shown in Table 1 below. <Evaluation of Transparency of Text on Adherend> The thermosensitive recording material was adhered to a printed material subjected to text printing, and it was evaluated whether the text could be read visually. For further numerical evaluation, the heat-sensitive recording material was adhered to the following two types of adherends, and the reflection optical density was measured from the heat-sensitive recording material side using a Macbeth RD918 (visual filter). Adherend 1 High quality paper (optical density 0.077) Adherend 2 Black construction paper (optical density 1.30)

The smaller the difference between the optical density when adhered to the adherend 1 and the optical density when adhered to the adherend 2, the thermosensitive recording material through which the print on the adherend is less visible. Conversely, the larger the difference, the more easily the heat-sensitive recording material allows the print on the adherend to be seen through.

[0059]

[Table 1]

As is clear from Table 1 above, the heat-sensitive recording materials of Examples 1 to 7 in which the backcoat layer contained a coloring pigment,
In the heat-sensitive recording materials of Examples 8 to 11 in which the adhesive layer contained a color pigment, the characters on the adherend were not legible, indicating that printing on the adherend was difficult to see through.

The measurement results of the optical densities of the heat-sensitive recording materials of Examples 1 to 11 compared to the heat-sensitive recording materials of Comparative Examples 1 to 4 show that the optical densities of the heat-sensitive recording materials when bonded to two types of adherends were compared. Is remarkably small, and supports the visual evaluation.

Further, the heat-sensitive recording materials of Examples 1 to 4, 6, 8, and 10 which were provided with an overcoat layer for improving the scratch resistance and the chemical resistance, were printed on the adherend. Is a heat-sensitive recording material that is difficult to see through and has excellent scratch resistance and chemical resistance. Further, the thermal recording materials of Examples 1 to 5, 8 and 9 in which an undercoat layer was provided to improve the thermal responsiveness, the printing of the adherend was difficult to be seen through, and the thermal sensitive recording material was excellent in thermal responsiveness. It is.

The heat-sensitive recording materials of Examples 1 to 11 in which the back coat layer or the adhesive layer was colored were harder to forge than the heat-sensitive recording materials of Comparative Examples 1 to 4 which were not colored. .

[0064]

As is clear from the examples, the heat-sensitive recording material of the present invention has a colored backcoat layer or an adhesive layer, so that it is difficult for strike-through to occur and is effective in preventing forgery. Useful as a thermal recording material.

Claims (4)

[Claims] 1. A support having a opacity of 70% or more, a heat-sensitive recording layer that develops color by heating, a backcoat layer on another surface, and an adhesive layer on the backcoat layer. The heat-sensitive recording material according to claim 1, wherein at least one of the back coat layer and the adhesive layer contains at least one kind of a coloring pigment or a dye. 2. The heat-sensitive recording material according to claim 1, wherein an overcoat layer is further provided on the heat-sensitive recording layer. 3. The heat-sensitive recording material according to claim 1, wherein an undercoat layer is provided between the support and the heat-sensitive recording layer. 4. The heat-sensitive recording material according to claim 1, wherein the content of at least one kind of the coloring pigment or the dye is 0.01 to 0.2 g / m ² .