JP2003094808A - Heat sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat sensitive recording material, which is high in sensitivity and excellent in the cutting properties thereof. SOLUTION: In the heat sensitive recording material formed by providing at least a heat sensitive recording layer on a synthetic paper, the synthetic paper such as a polypropylene film including a fine inorganic power or the like has at least a layer with voids under the condition that the density of the layer with the voids is 0.50 to 0.75 g/cm<3> and the Ohken type smoothness of the surface of a layer coming into contact with the heat sensitive layer of the synthetic paper is 3,000 to 30,000 s.

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, and more particularly to a heat-sensitive recording material utilizing a color reaction between a leuco dye and a color developer.

[0002]

2. Description of the Related Art A heat-sensitive recording material is generally a heat-sensitive recording layer containing a leuco dye and a color developer as a main component on a support such as paper or plastic film. A colored image can be obtained by heating with a lamp or the like. Compared to other recording materials, this type of recording material can perform recording in a short time with a relatively simple device without performing complicated processing such as development and fixing, and has less noise and environmental pollution. Due to its low cost, it is used for copying books, documents, etc., as well as electronic calculators, facsimiles, printers, ticket vending machines, labels,
Widely used as a recording material in various fields such as recorders. Further, in recent years, there has been a demand for a high-strength heat-sensitive recording material having improved paper quality strength, instead of a conventional plain paper for a plastic film or the like. A heat-sensitive recording material using a plastic film or the like has a higher smoothness and a better heat insulating property than a heat-sensitive recording material using a plain paper, and is therefore superior in terms of sensitivity corresponding to high-speed recording. In addition, in recent years, JP-A-5
No. 573, etc., a means is disclosed in which by providing an undercoat layer having plastic spherical hollow particles, even when plain paper is used, sensitivity equal to or higher than that when a plastic film is used is obtained. There is a demand for higher sensitivity of a heat-sensitive recording material using a plastic film or the like.

However, when a plastic film or the like is used and an undercoat layer having plastic spherical hollow particles is provided as in JP-A-5-573, coating of the heat-sensitive layer is caused by voids generated in the undercoat layer. Occasionally, there are new problems such as flicker and uneven coating, which were not problems with conventional plain paper. As a cause of this trouble, when an undercoat layer having plastic spherical hollow particles is provided, and a thermosensitive recording layer is provided thereon, the voids in the undercoat layer are replaced with the thermosensitive recording layer coating liquid and replaced. This is because air appears on the front surface or the back surface, but when an undercoat layer having plastic spherical hollow particles is provided on plain paper and a thermal recording layer is provided on it, plain paper is normally air-permeable. While air escapes from the back surface of the paper, when a plastic film or the like is used to provide an undercoat layer having plastic spherical hollow particles and a thermosensitive recording layer is provided thereon, the thermosensitive recording layer coating liquid was replaced. Since the air in the undercoat layer appears on the thermosensitive recording layer, it is considered that cissing or uneven coating may occur during coating.

Further, when the support is replaced by a conventional plain paper with a plastic film or the like, while such a material has improved paper quality strength, it is mounted in a printer for printing, and after printing, the recording material is cut. If you try to do so, it will have very poor sharpness (cutability), it will not cut lightly, it will not cut straight, and if you try to cut it forcibly your hand may be injured.

As described above, when a plastic film or the like is used as a support for the heat-sensitive recording material, there is no repellency or coating unevenness during coating of the heat-sensitive recording layer, and at the same time, there is no background fog at high temperature and storage is possible. It is also required to have good properties.

[0006]

The present invention has high sensitivity and
Moreover, it is an object of the present invention to provide a heat-sensitive recording material having excellent cutting property of the recording material.

[0007]

DISCLOSURE OF THE INVENTION As a result of intensive studies made by the present inventors to improve the sensitivity of a heat-sensitive recording material, the use of synthetic paper having a specific density and smoothness as a support results in the above problems. Found that
The present invention has been completed.

That is, according to the present invention, there is provided a thermosensitive recording material in which at least a thermosensitive recording layer is provided on a synthetic paper, the synthetic paper having a layer having at least voids, and the density of the layer having the voids. Is 0.50 to 0.75 g / cm ³ ,
Further, there is provided a heat-sensitive recording material characterized in that the surface of the layer of the synthetic paper which is in contact with the heat-sensitive recording layer has an Oken type smoothness of 3,000 to 30,000 seconds. Further, according to the present invention, the synthetic paper is formed on the surface of the layer having cavities on the thermosensitive recording layer side.
There is provided the above-mentioned heat-sensitive recording material, which is characterized by having at least other layers. Further, according to the present invention, there is provided the above thermosensitive recording material, wherein the synthetic paper is calendered. Furthermore, according to the present invention, there is provided the heat-sensitive recording material, wherein the synthetic paper is a polypropylene film containing an inorganic fine powder.

The high sensitivity of the heat-sensitive recording material is achieved by increasing the heat insulating property of the support, and the heat insulating property has a high void ratio (hollow ratio, void ratio) of the support (hence lower density). However, the density of conventional synthetic paper is
Usually, it is 0.85 g / cm ³ or more, and when such a synthetic paper is used as a support for a thermal recording material, the current sensitivity cannot be exceeded. Recently 0.85g / cm ³
A synthetic paper having a lower density of 0.75 g / cm ³ or less has been developed, a thermosensitive recording layer is provided with the synthetic paper as a support, a thermosensitive recording material is prepared, and the characteristics are evaluated. As a result, this synthetic paper is used. As a result, it has been found that the sensitivity is improved remarkably than ever before. Further, the surface smoothness of the conventional synthetic paper was about 2000 seconds in terms of Oken type smoothness, but it was found that the sensitivity was further improved by using one having 3000 seconds or more as a support. It is presumed that the higher the surface smoothness of the heat-sensitive recording material, the better the adhesion to the head (so-called head touch), the higher the heat transfer efficiency, and the higher the heat recording sensitivity.

In the present invention, by combining these two elements for improving the sensitivity, that is, in a heat-sensitive recording material, synthetic paper is used as the support, and the density of the synthetic paper is 0.75 g / cm ³ or less. The heat energy supplied from the thermal head is effectively utilized by using the above-mentioned synthetic paper and increasing the surface smoothness by setting the surface of the surface of the synthetic paper in contact with the heat-sensitive recording layer to Oken type smoothness of 3000 seconds or more. It was possible to improve the sensitivity of the thermosensitive recording material.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The synthetic paper which is the support of the heat-sensitive recording material of the present invention will be described. Synthetic paper usually consists mainly of a resin film (plastic film), and has properties similar to those of paper. By incorporating a cavity in the film layer, the fibrous body of paper is made similar. In many cases, inorganic fine particles are added to the film layer, if necessary. As described above, the synthetic paper (support) of the heat-sensitive recording material of the present invention has at least a layer having voids, and the density of the layer having voids is 0.50 to 0.50.
0.75 g / cm ³ , and the surface of the layer in contact with the heat-sensitive recording layer of synthetic paper has an Oken smoothness of 3000 to 30000.
Seconds.

When the density of the layer having the voids of the synthetic paper is low, the cuttability is also improved, but when it is less than 0.50 g / cm ³ (that is, the void ratio is very large), the mechanical strength and the like are lowered. It is not practical, while 0.75 g / cm ³
If it is larger (that is, the void ratio is smaller), the heat insulation becomes insufficient as described above, so that the thermal energy supplied from the thermal head cannot be effectively used, resulting in low sensitivity. I will end up.

If the surface of the layer of the synthetic paper in contact with the heat-sensitive recording layer has an Oken type smoothness of less than 3000 seconds, the smoothness of the surface is lowered and the adhesion with the thermal head cannot be obtained. The sensitivity will be low. On the other hand, the upper limit of 30
000 seconds is the upper limit of the synthetic paper that can be realized, and it is not practical beyond this. In the present invention, the surface of the layer in contact with the heat-sensitive recording layer of the synthetic paper refers to the surface of the layer in direct contact with the heat-sensitive recording layer, and may be a layer having a cavity on which a non-hollow layer is provided. For example, the surface of the layer is the surface of the layer, and the surface of the layer, if there is a layer provided thereon. In the present invention, the density is used as a measure of the porosity, but other measures such as xcc / 100 g (the amount of voids in the volume of 100 g solid content), y% (the ratio of voids to the volume of the layer of a unit area), etc. , Which can be converted to each other by the desired calculation.

As described above, in the heat-sensitive recording material of the present invention, by lowering the density of the synthetic paper which is the support, not only the cuttability but also the heat insulating property is improved, and the heat energy supplied from the thermal head is effective. It has the effect of being usable. By smoothing the surface of the synthetic paper, the surface of the heat-sensitive recording layer is smoothed, and the effect of making good contact with the thermal head is exhibited. Therefore, the sensitivity of the synthetic paper and the smoothness of the surface of the synthetic paper are important factors, and if the density of the synthetic paper is low, the greater effect can be obtained if the smoothness of the surface of the synthetic paper is higher. vice versa,
When the density of the synthetic paper becomes high, the sensitivity is lowered, and the cuttability is not good when cut after printing with a printer, and the cuttability is very poor. Further, if the smoothness of the surface of the synthetic paper becomes low, not only the sensitivity is lowered but also the definition of the image is lowered.

The synthetic paper used in the present invention can use a thermoplastic resin such as polyolefin-based, polystyrene-based, polyester-based, or polyvinyl chloride as a main raw material. As the inorganic fine powder added to the synthetic paper, calcium carbonate, calcined clay, diatomaceous earth, talc, titanium oxide, barium sulfate, aluminum sulfate, silica, etc. are used, and the particle size is preferably 12 μm or less.

The synthetic paper used in the present invention is produced by a fiber method, a film method (extrusion method, surface treatment method, surface coating method) or the like, and is obtained in the range of the density and the smoothness. If it can be manufactured by all manufacturing methods.

For example, in the above-mentioned synthetic paper which is a support of the heat-sensitive recording material of the present invention, an inorganic fine powder is added to a synthetic paper-forming material mainly made of a synthetic resin such as polypropylene and the like in the film forming step. When it is deformed, it can be manufactured by biaxially stretching it, and by stretching it vertically and horizontally, the voids around the fine powder extend vertically and horizontally, and the resin is three-dimensionally intricately overlapped to form a layer direction. Looking at the cross section, the structure can be made as if the paper fibers were intertwined.

The leuco dyes used in the heat-sensitive recording layer of the present invention may be used alone or in admixture of two or more, and as such leuco dyes, those used in this kind of heat-sensitive recording material may be arbitrarily used. The leuco compounds of dyes such as triphenylmethane type, fluorane type, phenothiazine type, auramine type, spiropyran type and indolinophtalide type dyes are preferably used. Specific examples of such leuco dyes include those shown below. 3,3-bis (p-dimethylaminophenyl) -phthalide, 3,3-bis (p-dimethylaminophenyl) -6
-Dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis (p-dimethylaminophenyl) -6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3, 3-bis (p-dibutylaminophenyl) phthalide, 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3-diethylamino-7-chlorofluorane, 3-
Diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3- (Np
-Tolyl-N-ethylamino) -6-methyl-7-anilinofluorane, 2- {N- (3'-trifluoromethylphenyl) amino} -6-diethylaminofluorane, 2- {3,6- Bis (diethylamino) -9- (o
-Chloranilino) xanthyl lactam benzoate}, 3
-Diethylamino-6-methyl-7- (m-trichloromethylanilino) fluorane, 3-diethylamino-7
-(O-Chloranilino) fluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-di-n-
Butylamino-7-o-chloroanilino) fluorane,
3-N-methyl-N, n-amylamino-6-methyl-
7-anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3- (N, N -Diethylamino) -5-methyl-7- (N, N-dibenzylamino) fluorane, benzoylleucomethylene blue, 6'-chloro-8'-
Methoxy-benzoindolino-spiropyran, 6'-bromo-3'-methoxy-benzoindolino-spiropyran, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5 ' Chlorphenyl) phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-nitrophenyl) phthalide, 3- (2'-hydroxy-
4'-diethylaminophenyl) -3- (2'-methoxy-5'-methylphenyl) phthalide, 3- (2'-methoxy-4'-dimethylaminophenyl) -3- (2 '
-Hydroxy-4'-chloro-5'-methylphenyl)
Phthalide, 3- (N-ethyl-N-tetrahydrofurfuryl) amino-6-methyl-7-anilinofluorane,
3-N-ethyl-N- (2-ethoxypropyl) amino-6-methyl-7-anilinofluorane, 3-N-methyl-N-isobutyl-6-methyl-7-anilinofluorane, 3- Morpholino-7- (N-propyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7
-Trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7- (N-benzyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7
-(Di-p-chlorophenyl) methylaminofluorane, 3-diethylamino-5-chloro-7- (α-phenylethylamino) fluorane, 3- (N-ethyl-p
-Toluidino) -7- (α-phenylethylamino) fluorane, 3-diethylamino-7- (o-methoxycarbonylphenylamino) fluorane, 3-diethylamino-5-methyl-7- (α-phenylethylamino)
Fluorane, 3-diethylamino-7-piperidinofluorane, 2-chloro-3- (N-methyltoluidino)-
7- (pn-butylanilino) fluorane, 3-di-
n-Butylamino-6-methyl-7-anilinofluorane, 3,6-bis (dimethylamino) fluorenspiro (9,3 ')-6'-dimethylaminophthalide, 3-
(N-benzyl-N-cyclohexylamino) -5,6
-Benzo-7-α-naphthylamino-4'-promofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-diethylamino-6-methyl-7-
Mesitidino-4 ', 5'-benzofluorane, 3-N-
Methyl-N-isopropyl-6-methyl-7-anilinofluorane, 3-N-ethyl-N-isoamyl-6-methyl-7-anilinofluorane, 3-diethylamino-
6-methyl-7- (2 ', 4'-dimethylanilino) fluorane, 3-morpholino-7- (N-propyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7-trifluoromethylanilinoflu Olane, 3-diethylamino-5-chloro-7- (N-benzyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7- (di-p-chlorophenyl) methylaminofluorane, 3-diethylamino-5- Chlor- (α-phenylethylamino) fluorane, 3- (N-ethyl-p-
Toluidino) -7- (α-phenylethylamino) fluorane, 3-diethylamino-7- (o-methoxycarbonylphenylamino) fluorane, 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluorane, 3 -Diethylamino-7-piveridinofluorane, 2-chloro-3- (N-methyltoluidino) -7
-(P-N-butylanilino) fluorane, 3,6-bis (dimethylamino) fluorenspyrro (9,3 ')-
6'-dimethylaminophthalide, 3- (N-benzyl-
N-cyclohexylamino) -5,6-benzo-7-α
-Naphthylamino-4'-bromofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3
-N-ethyl-N-(-2-ethoxypropyl) amino-6-methyl-7-anilinofluorane, 3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-
7-anilinofluorane, 3-diethylamino-6-methyl-7-mesitidino-4 ', 5'-benzofluorane, 3-p-dimethylaminophenyl) -3- {1,1
-Bis (p-dimethylaminophenyl) ethylene-2-
Il} phthalide, 3- (p-dimethylaminophenyl)
-3- {1,1-bis (p-dimethylaminophenyl)
Ethylene-2-yl} -6-dimethylaminophthalide,
3- (p-dimethylaminophenyl) -3- (1-p-
Dimethylaminophenyl-1-phenylethylene-2-
Yl) phthalide, 3- (p-dimethylaminophenyl)
-3- (1-p-Dimethylaminophenyl-1-p-chlorophenylethylene-2-yl) -6-dimethylaminophthalide, 3- (4'-dimethylamino-2'-methoxy) -3- (1 "-P-dimethylaminophenyl-1"
-P-chlorophenyl-1 ", 3" -butadiene-4 "-
Yl) benzophthalide, 3- (4'-dimethylamino-
2'-benzyloxy) -3- (1 "-p-dimethylaminophenyl-1" -phenyl-1 ", 3" -butadiene-4 "-yl) benzophthalide, 3-dimethylamino-
6-Dimethylamino-fluorene-9-spiro-3'-
(6'-Dimethylamino) phthalide, 3,3-bis (2
-(P-Dimethylaminophenyl) -2-p-methoxyphenyl) ethenyl) -4,5,6,7-tetrachlorophthalide, 3-bis {1,1-bis (4-pyrrolidinophenyl) ethylene- 2-yl} -5,6-dichloro-
4,7-dipromophthalide, bis (p-dimethylaminostyryl) -1-naphthalenesulfonylmethane, bis (p-dimethylaminostyryl) -1-p-tolylsulfonylmethane and the like.

As the color developer used in the heat-sensitive recording layer of the present invention, various electron-accepting compounds which develop the above leuco dye upon contact, such as phenolic compounds, thiophenolic compounds, thiourea derivatives, organic compounds. Acids and metal salts thereof are preferably applied, and specific examples thereof include the following, but are not limited thereto. 4,4'-isopropylidene bisphenol, 4,4 '
-Isopropylidene bis (o-methylphenol),
4,4'-secondary butylidene bisphenol,
4,4'-isopropylidene bis (2-tert-butylphenol), zinc p-nitrobenzoate, 1,3,3
5-tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid, 2,2
-(3,4'-dihydroxydiphenyl) propane, bis (4-hydroxy-3-methylphenyl) sulfide, 4- {β- (p-methoxyphenoxy) ethoxy}
Salicylic acid, 1,7-bis (4-hydroxyphenylthio) -3,5-dioxaheptane, 1,5-bis (4-
Hydroxyphenylthio) -5-oxapentane, phthalic acid monobenzyl ester monocalcium salt, 4,4′-
Cyclohexylidene diphenol, 4,4'-isopropylidene bis (2-chlorophenol), 2,2'-methylene bis (4-methyl-6-tert-butylphenol), 4,4'-butylidene bis (6-tert-butyl) -2-methyl) phenol, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-) Cyclohexylphenyl) butane, 4,4'-thiobis (6-tert-butyl-
2-methyl) phenol, 4,4'-diphenol sulfone, 4-isopropoxy-4'-hydroxydiphenyl sulfone, 4-benzyloxy-4'-hydroxydiphenyl sulfone, 4,4'-diphenol sulfoxide, p-hydroxy. Isopropyl benzoate, benzyl p-hydroxybenzoate, benzyl protocatechuate, stearyl gallate, lauryl gallate, octyl gallate, 1,3-bis (4-hydroxyphenylthio) -propane, N, N′-diphenylthio Urea, N, N'-di (m-chlorophenyl) thiourea, salicylanilide,
Bis- (4-hydroxyphenyl) acetic acid methyl ester, bis- (4-hydroxyphenyl) acetic acid benzyl ester, 1,3-bis (4-hydroxycumyl) benzene, 1,4-bis (4-hydroxycumyl) benzene,
2,4'-diphenol sulfone, 2,2'-diallyl-4,4'-diphenol sulfone, 3,4-dihydroxyphenyl-4'-methyldiphenyl sulfone, 1-
Zinc acetyloxy-2-naphthoate, zinc 2-acetyloxy-1-naphthoate, 2-acetyloxy-3-
Zinc naphthoate, α, α-bis (4-hydroxyphenyl) -α-methyltoluene, antipyrine complex of zinc thiocyanate, tetrabromobisphenol A, tetrabromobisphenol S, 4,4′-thiobis (2-methylphenol) , 4,4'-thiobis (2-chlorophenol) and the like. In the heat-sensitive recording material of the present invention, the developer is 1 to 20 parts by weight, preferably 2 to 10 parts by weight, relative to 1 part by weight of the color former (leuco dye). The developers can be applied alone or in combination of two or more.

In order to produce the heat-sensitive recording material of the present invention,
When the leuco dye and the color developer are bound and supported on the support, various commonly used binder resins can be appropriately used, and specific examples thereof include the following. Polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylic ester copolymer, acrylamide / acrylic ester / methacrylic acid Terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein and other water-soluble polymers, polyvinyl acetate, Polyurethane, polyacrylic acid,
Emulsion of polyacrylic acid ester, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer, etc., latex of styrene / butadiene copolymer, styrene / butadiene / acrylic copolymer, etc.

Further, in the heat-sensitive recording layer of the present invention, various heat-fusible substances can be used as a heat sensitivity improver together with the leuco dye and the color developer, if necessary.
Specific examples thereof include the followings, but are not limited to these. Fatty acids such as stearic acid and behenic acid, fatty acid amides such as stearic acid amide and palmitic acid amide, fatty acid metal salts such as zinc stearate, aluminum stearate, calcium stearate, zinc palmitate and zinc behenate, p-benzyl Biphenyl, terphenyl,
Triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, phenyl β-naphthoate, phenyl 1-hydroxy-2-naphthoate, 1
-Methyl hydroxy-2-naphthoate, diphenyl carbonate, glare coal carbonate, dibenzyl terephthalate, dimethyl terephthalate, 1,4-dimethoxynaphthalene, 1,4-diethoxynaphthalene, 1,4-
Dibenzyloxynaphthalene, 1,2-diphenoxyethane, 1,2-bis (3-methylphenoxy) ethane,
1,2-bis (4-methylphenoxy) ethane, 1,4
-Diphenoxy-2-butene, 1,2-bis (4-methoxyphenylthio) ethane, dibenzoylmethane, 1,
4-diphenylthiobutane, 1,4-diphenylthio-
2-butene, 1,3-bis (2-vinyloxyethoxy) benzene, 1,4-bis (2-vinyloxyethoxy) benzene, p- (2-vinyloxyethoxy) biphenyl, p-aryloxybiphenyl, p -Propargyloxybiphenyl, dibenzoyloxymethane, dibenzoyloxypropane, dibenzyl disulfide,
1,1-diphenylethanol, 1,1-diphenylpropanol, p-benzyloxybenzyl alcohol,
1,3-phenoxy-2-propanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene,
N-octadecylcarbamoylbenzene, 1,2-bis (4-methoxyphenoxy) propane, 1,5-bis (4-methoxyphenoxy) -3-oxapentane, dibenzyl oxalate, bis (4-methylbenzyl) oxalate, Bis (4-chlorobenzyl) oxalate and the like.

In the heat-sensitive recording layer, if necessary, auxiliary additives commonly used in heat-sensitive recording materials of this type,
For example, a filler, a dispersant, a color image stabilizing agent, an antioxidant, an antifoaming agent, a light stabilizer, a fluorescent whitening agent, a surfactant and the like can be used in combination. In this case, examples of the filler include calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, surface-treated calcium and silica, and other inorganic fine powders. , Urea-formalin resin, styrene / methacrylic acid copolymer, polystyrene resin, crosslinkable polymethylmethacrylate, polyvinylidene chloride, acrylonitrile-vinylidene chloride-methylmethacrylate copolymer, etc. it can.

Further, in the present invention, a protective layer is provided for the purpose of improving the head matching property (meaning slipperiness with the head, abrasion resistance, stain resistance, sticking resistance, etc.), or a heat-sensitive recording layer and synthetic paper. An undercoat layer (underlayer) may be provided for the purpose of improving color development and adhesiveness between and, and these layers may have conventional components within a range not impairing the object of the present invention, such as a resin and a filler, A heat-fusible substance (or lubricant) and a surfactant can be contained. Specific examples of the resin, the filler and the heat-fusible substance in this case include the same as those exemplified in connection with the heat-sensitive recording layer. Regarding the layer structure, a back layer may be provided, if necessary, in addition to the protective layer and the undercoat layer.

The heat-sensitive recording material of the present invention is formed by a conventionally known method, and the coating method for forming each layer is an air knife method, a wire bar method, a blade method, a reverse roll method, a slit die method or the like. Known methods can be used. The surface of the heat-sensitive recording material of the present invention and, if necessary, the surface of the undercoat layer, the heat-sensitive recording layer and the protective layer can be smoothed by a super calender, a gloss calender, a machine calender or the like.

[0025]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.
All parts and% shown below are based on weight.

(Production Example of Synthetic Paper A) Mixture a Polypropylene 94 parts Calcium carbonate 6 parts Mixture a having the above composition is mixed and agitated, and the resulting film is extruded through a die slit after the extruder is compatible and kneaded. The film obtained by stretching is 10 kg /
The calender treatment under a pressure of cm ² gave a density of 0.71 g / cm ³ , and one surface had a Oken type smoothness of 33.
A 00 second synthetic paper A was prepared.

(Production Example of Synthetic Paper B) In the production example of the synthetic paper A, except that the calender treatment at a pressure of 10 kg / cm ² is changed to the calender treatment at a pressure of 30 kg / cm ^2. A synthetic paper B having a density of 0.69 g / cm ³ and an Oken type smoothness on one surface of 5500 seconds was produced in the same manner as in the production example of the synthetic paper A.

(Production Example of Synthetic Paper C) A film obtained by kneading polypropylene and extruding through the die slit is laminated on the surface of the film obtained by extruding through the die slit in the production example of synthetic paper A, and obtained. The film obtained by biaxially stretching the obtained laminated structure film was subjected to a calendering treatment at a pressure of 10 kg / cm ² to prepare a synthetic paper C having a surface of one side having an Oken type smoothness of 30,000 seconds. . At this time, the density of the film portion in the synthetic paper C was 0.69 g / cm ³ .

(Production Example of Synthetic Paper D) In the production example of the synthetic paper A, the density is 0.76 g in the same manner as in the production example of the synthetic paper A except that the biaxial stretching and the calender treatment are not carried out. / Cm ³ , Oken type smoothness of one surface is 48
A 0 second synthetic paper D was prepared.

(Production Example of Synthetic Paper E) In the production example of the synthetic paper A, the density was 0.78 g / c in the same manner as in the production example of the synthetic paper A except that the biaxial stretching treatment was not carried out.
A synthetic paper E having a surface area of m ³ and an Oken type smoothness of 3800 seconds on one surface was prepared.

(Production Example of PET Film F) In the production example of the synthetic paper A, the density of 1. was obtained in the same manner as in the production example of the synthetic paper A except that the polypropylene in the mixture a was changed to polyethylene terephthalate (PET). 02 g / cm ³ ,
A PET film F having an Oken type smoothness of 30,000 seconds on one surface was produced.

Example 1 The following thermosensitive recording layer coating liquid and protective layer coating liquid were prepared. <Preparation of coating liquid for thermosensitive recording layer> [Solution A] 2-anilino-3-methyl-6-N-methyl-N-cyclohexylaminofluorane 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts water 60 seconds [solution B] 4-isopropoxy-4'-hydroxydiphenyl sulfone 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts water 60 parts [solution C] silica 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts water 60 parts [solution D] oxalic acid di ( p-Methylbenzyl) ester 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts water 60 parts Dispersion and pulverization of the mixture having the above composition for 3 hours with a Santo grinder, [solution A], [solution B], [solution C], [solution] D
Liquid] was prepared. [Thermal recording layer coating liquid] [A liquid] 16 parts [B liquid] 50 parts [C liquid] 16 parts [D liquid] 16 parts Water 2 parts The thus obtained thermal recording layer coating liquid has a density of 0. ．
71 g / cm ³ surface of synthetic paper A with Oken type smoothness of 330
It was coated on the surface for 0 seconds so that the adhesion amount after drying was 4 g / m ³ , and dried to obtain a paper on which a thermal recording layer was coated. <Preparation of Coating Liquid for Protective Layer> [Liquid E] Aluminum hydroxide 20 parts Polyvinyl alcohol 10% aqueous solution 20 parts Water 60 parts [F liquid] Zinc stearate 20 parts 5% aqueous solution of methylcellulose 40 parts Water 40 parts Mixture of the above composition Were dispersed and pulverized for 3 hours with a Santo grinder to prepare [E liquid] and [F liquid]. [Protective Layer Coating Liquid] Polyvinyl alcohol 10% aqueous solution 34 parts [E Liquid] 20 parts [F Liquid] 1 part Water 45 parts The above mixture was stirred to prepare a protective layer coating liquid. The protective layer coating liquid thus obtained is coated on a thermal recording layer coated paper so that the adhesion amount after drying is 4 g / m ³ , dried and supercalendered to prepare a thermal recording material. did.

Example 2 In Example 1, synthetic paper B was used in place of synthetic paper A,
A heat-sensitive recording material was produced in the same manner as in Example 1 except that a heat-sensitive recording layer was provided on the surface of the surface of the synthetic paper B on which the Oken type smoothness was 5500 seconds.

Example 3 In Example 1, synthetic paper C was used in place of synthetic paper A, and a thermosensitive recording layer was provided on the surface of synthetic paper C on which Oken type smoothness was 30,000 seconds. A thermal recording material was produced in the same manner as in Example 1 except for the above.

Comparative Example 1 In Example 1, synthetic paper D was used in place of synthetic paper A,
A heat-sensitive recording material was prepared in the same manner as in Example 1 except that a heat-sensitive recording layer was provided on the surface of the synthetic paper D on which the Oken type smoothness was 480 seconds.

Comparative Example 2 In Example 1, synthetic paper E was used in place of synthetic paper A,
A heat-sensitive recording material was produced in the same manner as in Example 1 except that a heat-sensitive recording layer was provided on the surface of the synthetic paper E on which the Oken type smoothness was 3800 seconds.

Comparative Example 3 In Example 1, the PET film F was used instead of the synthetic paper A.
The Oken type smoothness of the surface of PET film F is 30 using
A heat-sensitive recording material was produced in the same manner as in Example 1 except that the heat-sensitive recording layer was provided on the surface on the side of 000 seconds.

<Evaluation of Thermal Recording Material> The thermal recording materials obtained in Examples and Comparative Examples were evaluated for sensitivity and cuttability. The evaluation methods and evaluation criteria are shown below. The results are shown in Table 1. [Sensitivity] Head thermal power 0.45 W / dot, line recording time 20 ms / line, scanning line density 8 × 3.85 in a thermal printing experimental device having a thin film head manufactured by Matsushita Electronic Components Co., Ltd.
Pulse width 0.3, 0.4, 0.
Printing was performed for 5 and 0.6 ms, and the printing density was measured with a Macbeth densitometer RD-914. The print density-print energy (when the power is constant, the print time is proportional) curve was used to evaluate the density in the middle before saturation. [Cutability] The sample of Example and Comparative Example was mounted on a printer UP-880 manufactured by Sony Corporation (a cutter is provided on the outside of the printer machine), and the cutability when cut with the cutter was visually evaluated. Evaluation criteria ○ ・ ・ ・ Straight cut △ ・ ・ ・ Sometimes it cannot be cut straight (pass level) × ・ ・ ・ It is very difficult to cut.

[0039]

[Table 1] From the above results, it can be seen that the thermosensitive recording material of the present invention has high sensitivity. Further, the thermosensitive recording material (Example 3), which uses a synthetic paper having a non-hollow layer on both sides of the hollow layer as a support, is slightly less cut.

[0040]

The heat-sensitive recording material of the present invention has at least a layer having voids as a support, and the density of the layer having voids is 0.50 to 0.75 g / cm ³ , and the heat-sensitive recording is carried out. Oken type smoothness of the surface of the layer that is in contact with the layer is 3000
By using the synthetic paper of -30000 seconds, the sensitivity is high and the cutting property of the recording material is excellent.

Claims (4)

[Claims] 1. A heat-sensitive recording material in which at least a heat-sensitive recording layer is provided on synthetic paper, wherein the synthetic paper has a layer having at least voids, and the density of the layer having voids is 0.5.
0 to 0.75 g / cm ³ , and the Oken type smoothness of the surface of the layer in contact with the heat-sensitive recording layer of the synthetic paper is 3000 to 30.
A heat-sensitive recording material characterized by being 000 seconds. 2. The heat-sensitive recording material according to claim 1, wherein the synthetic paper has one or more other layers on the surface of the layer having cavities on the heat-sensitive recording layer side. 3. The heat-sensitive recording material according to claim 1, wherein the synthetic paper is calendered. 4. The heat-sensitive recording material according to claim 1, 2 or 3, wherein the synthetic paper is a polypropylene film containing an inorganic fine powder.