JP3520648B2 - Thermal recording material - Google Patents

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 improvement of a heat-sensitive recording material provided with a heat-sensitive coloring layer containing a leuco dye and a color developer as main components on a support.

[0002]

2. Description of the Related Art Recently, various recording materials have been researched and developed and put to practical use in the information recording field in response to social demands such as diversification and increase of information, resource saving and pollution-free. Among them, the heat-sensitive recording material is (1) that a color image is recorded only by heating and a complicated developing step is not required, (2) it can be manufactured using a relatively simple and compact apparatus, and further the obtained recording The material is easy to handle and the maintenance cost is low. (3) In many cases, paper is used as the support. In this case, not only the support cost is low, but also the feel of the obtained recording material is improved. Also, because of its advantages such as being close to plain paper, it is used in the fields of computer output, printers such as calculators, recorders for medical measurement, low and high-speed facsimile fields, automatic ticket vending machines, thermal copying fields, and POS system. Are widely used in the label field and the like of the beam.

In the above-mentioned thermosensitive recording material, a thermosensitive coloring layer liquid containing a coloring component (for example, a leuco dye) capable of causing a coloring reaction by heating is usually coated on a support such as paper, synthetic paper or synthetic resin film. It is produced by drying, and the heat-sensitive recording material thus obtained records a color image by heating it with a hot pen or a thermal head.
As a conventional example of such a heat-sensitive recording material, for example, a heat-sensitive recording material disclosed in JP-B-43-4160 or JP-B-45-14039 can be cited. However, in the case of a leuco-type heat-sensitive recording material as described above, the stability of the recorded image is poor, and, for example, when the oil or the plasticizer of the plastic film comes into contact with the back surface, the recorded image is discolored and there is a defect or background. It had the drawback of discolored parts. In order to eliminate such drawbacks, thermal recording materials provided with various overcoat layers and backcoat layers have been proposed.

In order to improve the slipperiness of the thermal recording material with the thermal head and to make the printing smooth, wax such as metallic soap is added to the surface layer, or the surface of the thermal recording material and the thermal recording material. In most cases, a filler such as aluminum hydroxide, silica, or calcium carbonate is added to remove sticking or sticking, or a so-called head residue that a low-melting point material adheres to the thermal head during printing. . However,
Wax, which is a slip agent, has a drawback that the above-mentioned plasticizer resistance of the overcoat layer is lowered in place of improving the slipperiness of the surface of the heat-sensitive recording material. In addition, if a wax having good plasticizer resistance is used, slipperiness is insufficient and printing noise becomes large at the time of printing, sticking occurs, and printing becomes inconvenient. It was not possible to achieve both plasticizer resistance.

Zinc stearate as a wax is relatively compatible in terms of slipperiness and plasticizer resistance, but the plasticizer resistance is still of insufficient quality. On the other hand, polyethylene wax and montan wax are both relatively compatible qualities as wax, and although they possess sufficient quality as plasticizer resistance, they are somewhat inferior in slipperiness and have poor print quality. Has no problem, but has a drawback that the printing sound during printing is loud.

Further, when these heat-sensitive recording materials are used as a label, an adhesive paste is attached to the back surface of the support.
Therefore, a back coat layer is often provided on the back surface of the support in order to protect the thermosensitive coloring layer from the smoothness of the back surface or the solvent of the viscous agent. The backcoat layer has almost the same main components as the overcoat layer, but since it does not require much head shavings and lubricity, conventionally, no lubricant is added, and the filler is less than that of the overcoat layer. However, there may be a problem when these back coat layers are provided.
Usually, when these thermal recording materials are produced on a factory scale, each coating liquid is applied to a roll-shaped base paper, dried, wound again in a roll shape, and then cured. May adhere and may not be rewound, or when rewound, a phenomenon may occur in which the surface of the recording material sticks to the back surface and peels off (blocking).

[0007]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to achieve both the above-mentioned drawbacks of the heat-sensitive recording material, the plasticizer resistance, the printing sound and the printing runnability, and the above-mentioned blocking resistance. To provide a heat-sensitive recording material.

[0008]

According to the present invention, firstly, a leuco dye and a color developer, which are colored by heat, are mainly formed on a support.
A thermosensitive recording material comprising a thermosensitive coloring layer contained as a component, and an overcoat layer provided on the upper surface thereof, wherein the overcoat layer serves as a lubricant , and at least one selected from polyethylene oxide wax and montan wax and silicone wax. There is provided a heat-sensitive recording material containing : and a filler . Secondly, the filler contained in the overcoat layer has a particle size of
There is provided the heat-sensitive recording material described in the first above, which is a filler of 2 to 8 μm . Thirdly, there is provided the heat-sensitive recording material described in the second, wherein the filler having a particle size of 2 to 8 μm is an organic filler.

[0009] That is, the heat-sensitive recording material of the present invention, since the provision of the overcoat layer containing the oxide Po triethylene wax or / and montan wax and silicon wax as a lubricant <br/>, plasticizer resistance In addition, the printing sound is excellent and the printing runnability is extremely excellent, and printing under high humidity is possible. Further, when a filler having a particle size of 2 to 8 μm is contained and an organic filler is used as the filler, the printing sound is further improved.

[0010]

The present invention will be described in more detail below. In the present invention, the overcoat layer contains wax as a lubricant. However, the back coat layer also has a lubricant
A wax may be contained as the above. Examples of the wax used in the present invention include polyethylene wax and montan wax, and the addition amount thereof is preferably 0.05 to 1.5 parts with respect to 1 part of the resin. The particle size is 0.
It is preferably 5 to 6 μm. Silicon wax is also used in the present invention, but the addition amount is preferably 0.01 to 1.0 part with respect to 1 part of the resin. If it is added more than this, the plasticizer resistance is lowered. These waxes can also be combined with other conventionally known waxes.

Examples of the wax used in combination in this case include candelilla wax, carnauba wax, rice wax, wood wax, jojoba oil and other plant waxes, beeswax, lanolin, whale wax and other animal waxes, and ceresin. Mineral waxes and their derivatives, paraffin, petrolatum, microcristan, petrolactam, and other petroleum waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch wax, hydrogenated castor oil, hydrogenated wax of hydrogenated castor oil derivatives, stearin Acids, oleic acid, erucic acid, lauric acid, sebacic acid, behenic acid, palmitic acid and other fatty acids, adipic acid, isophthalic acid and other amides, bisamides, esters, ketones, metal salts and their derivatives, alkyl- or amide-modified Silicone resin etc. It is below. Of course, these lubricants may be used in combination.

Examples of the filler having a particle diameter of 2 to 8 μm used in the present invention include silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate,
In addition to clay, kaolin, talc, inorganic fine powder such as surface-treated calcium and silica, organic fine powder such as urea-formalin resin, styrene / methacrylic acid copolymer, polystyrene resin, vinylidene chloride resin Among them, spherical particles are particularly preferable. Particularly effective among these are silica fillers and polymethylmethacrylate fillers. The addition amount is preferably 0.05 to 2 parts with respect to 1 part of the resin. In addition, other particle size 2μm
Can be used in combination with less than fillers.

The resin used for forming the overcoat layer in the present invention includes a water-soluble resin, an aqueous emulsion,
Hydrophobic resins and UV curable resins, as well as electron beam curable resins are included. Specific examples of the water-soluble resin include polyvinyl alcohol, modified polyvinyl alcohol, cellulose derivatives (methyl cellulose, methoxy cellulose, hydroxy cellulose, etc.), casein, gelatin,
Polyvinylpyrrolidone, styrene / maleic anhydride copolymer, diisobutylene / maleic anhydride copolymer, polyacrylamide, modified polyacrylamide, methyl vinyl ether / maleic anhydride copolymer, carboxyl modified polyethylene, polyvinyl alcohol / acrylamide block copolymer Coalesce, melamine formaldehyde resin,
Examples include urea and formaldehyde resins. Examples of the resin or hydrophobic resin for the aqueous emulsion include polyvinyl acetate, polyurethane, styrene / butadiene copolymer, styrene / butadiene / acrylic copolymer, polyacrylic acid, polyacrylic acid ester, vinyl chloride /
Examples thereof include, but are not limited to, vinyl acetate copolymer, polybutyl methacrylate, polyvinyl butyral, polyvinyl acetal, ethyl cellulose, ethylene / vinyl acetate copolymer and the like. Of these, water-soluble resins such as polyvinyl alcohol are preferable in view of plasticizer resistance. If necessary, a conventionally known cross-linking agent can be used as a water resistance agent for these water-soluble resins. In the present invention, the back coat
When a protective layer is provided, the tree used for the above overcoat layer
It is preferable to use the same one as the fat.

The leuco dyes used in the thermosensitive coloring layer of the present invention may be used alone or as a mixture of two or more kinds. As such leuco dyes, those applied to this type of thermosensitive material are arbitrarily applied. For example, 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, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- {N- (3'-trifluoromethylphenyl) amino} -6-diethylaminofluorane, 2- {3. 6-bis (diethylamino)-
9- (o-chloroanilino) xanthyl benzoate lactam}, 3-diethylamino-6-methyl-7- (m-trichloromethylanilino) fluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 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, benzoyl leuco methylene blue, 6'-chloro-
8'-methoxy-benzoindolino-spiropyran, 6 '
-Bromo-3'-methoxy-benzoindolino-spiropyran, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-chlorophenyl) 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) methylaminofluor Oran, 3-
Diethylamino-5-chloro-7- (α-phenylethylamino) fluorane, 3- (N-ethyl-p-toluidino) -7- (α-phenylethylamino) fluorane, 3-diethylamino-7- (o-methoxy Carbonylphenylamino) 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'-bromofluorane, 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-
Trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7- (N-benzyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7-
(Di-p-chlorophenyl) methylaminofluorane,
3-diethylamino-5-chloro- (α-phenylethylamino) fluorane, 3- (N-ethyl-p-toluidino) -7- (α-phenylethylamino) fluorane, 3-diethylamino-7- (o-methoxy Carbonylphenylamino) fluorane, 3-diethylamino-
5-methyl-7- (α-phenylethylamino) fluorane, 3-diethylamino-7-piperidinofluorane, 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
-Benz-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-yl} 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" -butadiene4 "-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-dibromophthalide,
Bis (p-dimethylaminostyryl) -1-naphthalenesulfonylmethane, bis (p-dimethylaminostyryl) -1-p-tolylsulfonylmethane and the like.

As the color developer used in the heat-sensitive color developing layer of the present invention, various electron-accepting compounds that cause the leuco dye to develop color upon contact, or oxidizing agents are used. Such materials are conventionally known, and specific examples thereof include the following, but are not limited to these.

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,
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 ' -Isopropylidenebis (2-chlorophenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4'-butylidenebis (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,
Isopropyl P-hydroxybenzoate, benzyl P-hydroxybenzoate, benzyl protocatechuate, stearyl gallate, lauryl gallate, octyl gallate,
1,3-bis (4-hydroxyphenylthio) -propane, N, N'-diphenylthiourea, 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, zinc 1-acetyloxy-2-naphthoate, 2-acetyloxy-
1-naphthoate zinc, 2-acetyloxy-3-naphthoate zinc, 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 color developer is contained in an amount of 1 to 20 parts, preferably 2 to 10 parts, per 1 part of the color former. The color developer can be applied alone or in combination of two or more kinds, and also in the case of the color developer, it can be applied alone or in combination of two or more kinds.

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 binders 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 and ethyl cellulose, polyacrylic acid sodium -Da, polyvinylpyrrolidone, acrylamide / acrylic acid ester copolymer, acrylamide / acrylic acid ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt , Water-soluble polymers such as polyacrylamide, sodium alginate, gelatin and casein, as well as polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylic acid ester, vinyl chloride / vinyl acetate copolymer, polybutylmethacrylate G, ethylene / vinyl acetate copolymer Emulsion and styrene / butadiene copolymers such as the body, styrene / butadiene / latex such as acrylic copolymer.

Further, in the present invention, various heat fusible substances can be used as the sensitivity improver, and specific examples thereof include the followings, but the present invention is not limited thereto. .

Fatty acids such as stearic acid and behenic acid, fatty acid amides such as stearic acid amide and palmitic acid amide, zinc stearate and aluminum stearate,
Fatty acid metal salts such as calcium stearate, zinc palmitate and zinc behenate, p-benzylbiphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, β
-Phenyl naphthoate, phenyl 1-hydroxy-2-naphthoate, methyl 1-hydroxy-2-naphthoate, diphenyl carbonate, glare call carbonate, dibencil 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) bifer, p-aryloxypphenyl, p-
Propagyloxybiphenyl, 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.

The heat-sensitive color-developing layer is prepared by uniformly dispersing or dissolving it in an organic solvent together with a color-developing agent, a color-developing agent, a binder, etc., coating it on a support and drying it, but the coating method is not particularly limited. Not done. The dispersed particle size of the color forming layer coating solution is preferably 10 μm or less, more preferably 5 μm or less, still more preferably 1 μm or less. The film thickness of the color forming layer is about 1 to 50 μm, preferably about 3 to 20 μm, though it depends on the composition of the color forming layer and the use of the heat-sensitive recording material. Further, if necessary, various additives commonly used in heat-sensitive recording paper may be added to the coating solution for color forming layer for the purpose of improving coatability or recording characteristics.

Either acidic paper or neutral paper can be used as the support in the present invention. Further, the release paper comprising the neutral paper support and the neutral paper preferably has a low calcium content. In this way, the neutral paper having a small amount of calcium and the release paper composed of the neutral paper can be obtained by reducing the ratio of the waste paper used for papermaking. Also,
Normally, calcium carbonate is used as an internal additive in the papermaking of neutral paper, and alkyl ketene dimer or alkenyl succinic anhydride is used as a sizing agent, while the internal additive is replaced with talc or clay, Obtained by combining with rosin size.

The recording method of the heat-sensitive recording material of the present invention is not particularly limited to a heating pen, a thermal head, laser heating or the like depending on the purpose of use.

[0026]

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

<Preparation of Coating Liquid> The following undercoat layer forming liquid, thermosensitive coloring layer forming liquid, and overcoat layer forming liquid are prepared.

(I) Preparation of Liquid for Forming Undercoat Layer Plastic spherical micro hollow particles (copolymer resin mainly composed of styrene / acryl, solid content concentration 27.5%, average particle diameter 1 μm, hollow ratio 50%) 36 Part Styrene / butadiene copolymer latex (solid content concentration 47.5%) 10 parts water 54 parts The above mixture was stirred and dispersed to prepare an undercoat layer forming liquid.

(II) Preparation of thermosensitive color forming layer forming liquid [Solution A] 3-dibutylamino-6-methyl-N-7-anilinofluorane-A 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts water 60 parts [solution B ] 4-Isopropoxy-4'-hydroxydiphenyl sulfone 20 parts 10% aqueous solution of polyvinyl alcohol 25 parts water 50 parts [solution C] silica 20 parts 5% aqueous solution of methyl cellulose 20 parts water 50 parts Each of the above mixtures is magnetic. It was pulverized for 2 days in a ball mill to prepare [solution A], [solution B] and [solution C].

[0030] [Thermal coloring layer forming liquid]     [A liquid] 15 parts     [B liquid] 45 parts     [C liquid] 45 parts     20% aqueous alkali solution of isobutylene / maleic anhydride copolymer                                                               5 copies The above mixture was stirred to prepare a thermosensitive coloring layer forming liquid.

(III) Preparation of Overcoat Layer Forming Liquid [Liquid D] Aluminum hydroxide 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts The above mixture was ground in a magnetic ball mill for 2 days [D
Liquid] was adjusted.

[0032] [Overcoat layer forming liquid 1]     [D liquid] 12.5 parts     Lubricant dispersion 20% (see Table 1) 2.5 parts     Carboxy modified polyvinyl alcohol (10%) aqueous solution 40 parts     Polyacrylamide epichlorohydrin cross-linking agent     (27.5%) aqueous solution 4.4 parts     Additive filler dispersion (20%) 8.0 parts     Water 33.0 parts

[0033] [Overcoat layer forming liquid 2]     [D liquid] 12.5 parts     Lubricant dispersion 20% (see table) 2.5 parts     Carboxy modified polyvinyl alcohol (10%) aqueous solution 40 parts     Polyacrylamide epichlorohydrin cross-linking agent     (27.5%) aqueous solution 4.4 parts     Additive filler dispersion (20%) 8.0 parts     Silicone wax (20%) (See table) 0.8 parts     Water 33.0 parts

The coating liquid of each layer prepared as described above is applied to the undercoat layer (intermediate layer) so that the amount of the coating liquid deposited on the support is 3.0 g / m ² , and the amount of the dye deposited on the undercoat layer is 0.
The thermosensitive color-developing layer was applied and dried so as to be 35 g / m ^2, and the resin adhesion amount was 1.6 g / m according to Table 1 and Table 2.
m ² and an overcoat layer on the back surface of the support, and a backcoat layer on the back surface of the support so that the amount of resin adhered is 0.7 g / m ² (the amounts of adhesion are dry amounts). After that, surface treatment with a super calender,
Samples of Examples and Comparative Examples were obtained. The samples obtained as described above were evaluated as follows.

<Evaluation> (1) Plasticizer resistance A sample that has been forcibly cured is printed with a heat block so that the image density becomes 1.30 with a Macbeth reflection densitometer. After that, three polymer wraps are placed on the printed surface, left at 40 ° C. for 15 hours, and the image density is measured by a Macbeth reflection densitometer.

(2) Printing Sound Forced curing of the sample is printed with a B-300 label printer manufactured by TEC at a speed of 3 inches, and the printing sound generated at that time is measured by a sound level meter for judgment. . (Background was 50 dB) ◎: Very quiet ○: Quiet and good ○ to △: Between ○ and △ △: Noisy can be used △ to ×: Between △ and × ×: Very noisy and used Impossible level

(3) Printing runnability at high temperature The cured sample was printed at 3 inches with a B-300 label printer manufactured by TEC under the conditions of 32 ° C. and 90% RH, and the runnability was evaluated. . ◎ Very good ○ Good △ Somewhat bad × bad

(4) Blocking Evaluation Thirty samples that were not cured were stacked, sealed in a bag, a weight (80 kg) was added to the stacked part, and forced curing was carried out at 50 ° C. for 15 hours. After that, peel off one sample at a time,
Examine the degree. ◎: No adhesion ○: Almost no adhesion ○ to △: Between ○ and △ △: Slightly adhered and the thermal layer surface is slightly peeled when peeling, but can be used △ to ×: Between △ and × ×: Adhesion , When peeling, the surface layer peels off and cannot be used

Examples 1 to 10 and Comparative Examples 1 to 7 Using the above overcoat layer forming liquid (1) or (2),
Without forming a back layer, Examples 1 to 10 and Comparative Examples 1 to 1
A thermal recording material of No. 7 was prepared. In addition, in Examples 1 to 10, the overcoat layer forming liquid (2) was used, and in others, the overcoat layer forming liquid (1) was used. The results are shown in Table 1.
-(1) to Table 1- (2) are shown.

[0040]

[Table 1- (1)]

[0041]

[Table 1- (2)]

[0052]

The heat-sensitive recording material of claim 1 is used as a lubricant.
<br/> set an overcoat layer containing a polyethylene wax and / or montan wax oxide and silicon wax only, since it contained more filler in the overcoat layer, plasticizer resistance, and excellent in printing noise The printing runnability is extremely excellent and printing under high humidity is possible. Claim 2
The heat-sensitive recording material of No. 1 contains the overcoat layer of Claim 1.
Since the particle size of the filler used is 2 to 8 μm , the effect of further improving the printing sound is added. The heat-sensitive recording material according to claim 3 is the overcoat layer according to claim 2, wherein
Since the organic filler is used as the filler, the effect of further improving the printing sound is added.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasutomo Mori 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) Reference JP-A-5-254249 (JP, A) JP JP 5-104859 (JP, A) JP 5-96853 (JP, A) JP 5-96852 (JP, A) JP 7-96665 (JP, A) JP 6-206375 (JP , A) JP-A-5-246140 (JP, A) JP-A-6-64326 (JP, A) JP-A-57-123088 (JP, A) JP-A-1-133783 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B41M 5/26-5/40

Claims (3)

(57) [Claims] 1. A leuco dye that develops heat on a support, and
A thermosensitive recording material comprising a thermosensitive coloring layer containing a color developer as a main component, and an overcoat layer provided on the upper surface thereof, wherein the overcoat layer serves as a lubricant, and an oxidized polyethylene wax and a montan wax are used. A filler containing at least one selected from
A heat-sensitive recording material characterized by containing: 2. A filler contained in the overcoat layer
Is a filler having a particle size of 2 to 8 μm
Heat-sensitive recording material according to claim 1, wherein that. 3. The heat-sensitive recording material according to claim 2, wherein the filler having a particle diameter of 2 to 8 μm is an organic filler.