JP2003276334A - Thermal recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal recording material which, under low temperature and low humidity conditions, does not cause a sticking phenomenon attributable to sticking of a heat melt of a thermal layer and a protective layer onto a head and is free from a deterioration in recording density, recording sensitivity, and storage stability of recorded images. <P>SOLUTION: This thermal recording material provided with a thermal color developing layer, capable of developing color upon exposure to heat, on the support, and provided with a protective layer, containing a binder resin, a crosslinking agent, a filler, and a release agent, on the thermal color developing layer, and is characterized in that the release agent is a hydrocarbon group- modified silicone oil. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal recording used in the fields of computer output, calculators and other printers, medical measurement recorders, low speed and high speed facsimiles, automatic ticket vending machines, handy terminals and the like. It is about materials.

[0002]

2. Description of the Related Art Conventionally, a heat-sensitive recording layer containing a colorless or light-colored leuco dye and a color developer which develops a color when the leuco dye is contacted is provided on a support such as paper, synthetic paper or plastic film. Heat between the leuco dye and the developer,
Various recording materials have been proposed which utilize a coloring reaction due to pressure or the like. This type of heat-sensitive recording material does not need to be subjected to complicated processing such as development and fixing, can be recorded in a short time with a relatively simple device, generates little noise, and has low cost. Due to its advantages, it is widely used as a recording material for computers, facsimiles, ticket issuing machines, label printers, recorders, handy terminals, etc. in addition to being used for copying books and documents.

Due to the widespread use of heat-sensitive recording materials, the frequency with which they are used outdoors is increasing, and there is a demand for recording material characteristics capable of printing under harsh environments such as low temperature and low humidity conditions. In particular,
Small label printers and printers for handy terminals that are vulnerable to motor torque are prone to sticking and transport defects under low temperature and low humidity conditions.

Conventionally, in a thermal recording material, in order to improve the water resistance and chemical resistance of a recorded image to improve the storability of the recorded image, and also to prevent the adhesion of head residue, head abrasion, sticking, etc. In order to improve the matching property, a protective layer containing a water-soluble resin, a pigment, a cross-linking agent, and the like as main components has been proposed (for example, Jikkou Sho 59).
No. 9909, Japanese Utility Model Publication No. 62-21616, Japanese Patent Publication No. 1-17478, Japanese Patent Publication No. 4-30918, Japanese Patent Publication No. 4-71716, Japanese Patent Publication No. 4-7767.
No. 2, etc.). Also, in JP-A-54-128347, the use of a styrene-acrylonitrile-butyl acrylate copolymer emulsion is disclosed in Japanese Patent Publication No. 4-221.
The use of polyurethane resin emulsion is proposed in Japanese Patent No. 53.

A silicone compound is added to the protective layer of the heat-sensitive recording material to improve running property and sticking (for example, JP-A-1-198386, JP-A-02-187).
No. 388 and Japanese Patent Laid-Open No. 03-002088). However, in small label printers and printers for handy terminals that have weak motor torque, the heat-sensitive layer and the protective layer cannot be formed under low temperature and low humidity conditions. There are new defects such as sticking phenomenon caused by the sticking of the hot melt to the head, deterioration of recording density and storability of recorded images, and increase in head residue adherence.
As a result, the current situation is that what is not sufficiently satisfactory is obtained.

Further, in recent years, since it has a high preservation characteristic,
(Poly) 4-hydroxybenzoic acid derivative and diphenyl sulfonic acid derivative, which have high utility value (JP-A-10-299)
No. 69), the high-melting-point color developer rapidly solidifies after thermal melting under low temperature and low humidity conditions, so that the hot melt easily sticks to the head and sticking phenomenon easily occurs. Therefore, there is an increasing demand for a thermosensitive recording medium which does not deteriorate the sticking resistance and the recording density and the storability of recorded images.

[0007]

DISCLOSURE OF THE INVENTION The present invention eliminates the sticking phenomenon caused by the hot melt of the heat sensitive layer and the protective layer sticking to the head under low temperature and low humidity conditions.
Further, it is an object of the present invention to provide a heat-sensitive recording material which does not reduce the recording density, recording sensitivity, and storability of recorded images.

[0008]

As a result of intensive studies to solve the above problems, the present invention has been completed. That is, according to the present invention, the following thermal recording material is provided.

(1) A thermosensitive recording comprising a thermosensitive coloring layer which is colored by heat on a support, and a protective layer containing a binder resin, a cross-linking agent, a filler and a releasing agent on the thermosensitive coloring layer. In the material, the release agent is a hydrocarbon group-modified silicone oil, which is a heat-sensitive recording material. (2) The heat-sensitive recording material as described in (1) above, wherein the binder resin is polyvinyl alcohol containing a reactive carbonyl group. (3) The heat-sensitive recording material as described in any of (1) and (2) above, wherein the crosslinking agent is a hydrazide compound. (4) The oil absorption of the filler is 50 ml / 100 g to 2
The above (1), which is 00 ml / 100 g
The heat-sensitive recording material according to any one of to (3). (5) The filler is 100 to 500% of the binder resin.
The heat-sensitive recording material as described in any one of (1) to (4) above. (6) The thermosensitive recording material according to any one of (1) to (5), wherein an intermediate layer containing thermoplastic hollow resin particles is provided between the support and the thermosensitive coloring layer. . (7) The thermosensitive coloring layer is selected from a (poly) 4-hydroxybenzoic acid derivative, a urea urethane compound, a diphenylsulfonic acid derivative, a compound having a sulfonylaminocarbonylamide group, and 4,4′-dihydroxydiphenylsulfone. The heat-sensitive recording material as described in any of (1) to (6) above, which contains at least one developer.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The heat-sensitive recording material of the present invention comprises a support, on which a heat-sensitive coloring layer and a protective layer are provided in this order.
The protective layer is characterized by containing a release agent made of a hydrocarbon group-modified silicone oil.

The inventors of the present invention are concerned with the use of a heat-sensitive recording material, in order to improve the sticking phenomenon caused by sticking of the heat-melted material of the heat-sensitive layer and the protection layer to the head under low temperature and low humidity conditions. Silicone compound (dimethylpolysiloxane emulsion / SH7036 / SH7024 manufactured by Toray Dow Corning Silicone Co., Ltd.)
And resin emulsion / SH7706 manufactured by Toray Dow Corning Silicone Co., Ltd.) have a small effect of improving the sticking phenomenon in a low temperature environment, and increasing the addition amount inhibits color development of the coloring layer. It was confirmed that it is difficult to achieve both the improvement of the sticking phenomenon and the reduction of the density of the color image and the deterioration of storability because the color density of the color image is reduced. As a release agent, an alkyl / aralkyl modified silicone oil (SM7001, SM7 manufactured by Toray Dow Corning Silicone Co., Ltd.)
002) is contained, the heat-melted material of the heat-sensitive layer and the protective layer prevents sticking to the head under low-temperature and low-humidity conditions, improves the sticking phenomenon, does not reduce the color density, and has excellent storage stability. It has been found that a recording material can be obtained. Further, in the present invention, by combining the resin contained in the protective layer, the cross-linking agent, the filler and the release agent, not only the color density, sticking property, storage stability, but also binding property, water resistance, printing property, etc. It is possible to obtain both good quality and good quality as a heat-sensitive recording material.

The hydrocarbon group-modified silicone oil used as a release agent in the present invention is a conventionally known substance, and various kinds thereof are known. Such compounds include, for example, alkyl-modified silicone oil, aralkyl-modified silicone oil, alkyl-aralkyl-modified silicone oil, and the like. These hydrocarbon group-modified silicone oils have an α value higher than that of silicone oils containing Si--H groups.
-Olefin or phenyl group-substituted-α-olefin and the like can be obtained. In this case, the number of carbon atoms of the hydrocarbon group is not particularly limited, but usually 2 to
12, preferably 3-8. These hydrocarbon group-modified silicone oils are commercially available from, for example, Toray Dow Corning Silicone Co., Ltd.
It is sold under the product name such as "7002".

The protective layer used in the present invention contains the above-mentioned hydrocarbon group-modified silicone oil as a binder resin, a crosslinking agent, a filler and a release agent.

The binder resin used for the protective layer is water-soluble, for example, polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as methoxycellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, styrene. / Maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, water-soluble polymers such as polyacrylamide, gelatin and casein. It is preferable to use a resin having high heat resistance, which is resistant to thermal dissolution and softening, to improve sticking, and from this viewpoint, polyvinyl alcohol containing a reactive carbonyl group is most preferable.

Polyvinyl alcohol containing a reactive carbonyl group can be produced by a known method such as saponification of a polymer obtained by copolymerizing a vinyl monomer containing a reactive carbonyl group and a fatty acid vinyl ester. Examples of the vinyl monomer containing a reactive carbonyl group include a group containing an ester bond and a group containing an acetone group.
A vinyl monomer having a diacetone group is preferable, and specifically, diacetone acrylamide or meta diacetone acrylamide is preferable. Examples of the fatty acid vinyl ester include vinyl formate, vinyl acetate and vinyl propionate, with vinyl acetate being preferred. Polyvinyl alcohol containing a reactive carbonyl group used in the present invention,
It may be obtained by copolymerizing a copolymerizable vinyl monomer. Examples of these copolymerizable vinyl monomers include acrylic acid ester, butadiene, ethylene, propylene, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, and itaconic acid. The content of the reactive carbonyl group in the polyvinyl alcohol containing the reactive carbonyl group used in the present invention is 0.5 mol% to 20 mol% in the polymer, and considering the water resistance, it is 2 mol% to 10 mol%. Ranges are particularly preferred. If it is less than 2%, the water resistance is not practically sufficient, and if it exceeds 10 mol%, no improvement in water resistance is observed and it becomes economically expensive. Polyvinyl alcohol having a reactive carbonyl group used in the present invention has a degree of polymerization of 300 to 3000 and 500 to 2200.
Is particularly preferred. The saponification degree is preferably 80% or more.

In the present invention, in order to make the binder resin a resin having high heat resistance that is less likely to be melted and softened by heat, it is advantageous to add a cross-linking agent to the protective layer to improve sticking. . As the cross-linking agent used in the present invention, a hydrazine cross-linking agent is preferably used. This hydrazine cross-linking agent should have a hydrazide group,
For example, carbohydrazide, oxalic acid dihydrazide, formic acid hydrazide, acetic acid hydrazide, malonic acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, azelaic acid hydrazide, sebacic acid dihydrazide, dodecane diacid dihydrazide, maleic acid, dihydrazide,
Itaconic acid dihydrazide, benzoic acid hydrazide, glutaric acid dihydrazide, diglycolic acid hydrazide, tartaric acid dihydrazide, malic acid dihydrazide, isophthalic acid hydrazide, terephthalic acid dihydrazide, 2,7-naphthoic acid dihydrazide, polyacrylic acid hydrazide and the like can be mentioned. Not limited to. In the present invention, two or more hydrazide compounds may be used in combination, or may be combined with other known cross-linking agents such as epichlorohydrin and glyoxal as long as the function is not impaired. However, among the hydrazide compounds, adipic acid dihydrazide is preferable in terms of water resistance and safety.

As the filler for the protective layer, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, inorganic fine particles such as surface-treated calcium and silica are used. In addition to powder, organic fine powder such as urea formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin can be used. In particular, in order to absorb the heat-melted material of the heat-sensitive layer and the protective layer and prevent sticking to the head, the protective layer should contain powder of silica, calcium carbonate, aluminum hydroxide or the like having high oil absorption. Is preferred. The oil absorption (JIS K510121.) Is
The amount is preferably 50 ml / 100 g to 200 ml / 100 g, and the amount of filler used is preferably 100 to 500 parts (parts by weight) per 100 parts of the binder resin. If the oil absorption is less than 50 ml / 100 g, it will not be effective because it will not be able to absorb the hot melt, and 200 ml / 1
If it exceeds 00 g, a color-developed image and a reduction in sensitivity are observed due to the hiding effect. The amount of filler used is 100
If the amount is less than 500 parts, there is no effect because the hot melt cannot be completely absorbed. If the amount is more than 500 parts, a color-developed image and a decrease in sensitivity are observed due to the hiding effect.

In the present invention, the amount of the hydrocarbon group-modified silicone oil contained in the protective layer is 50 to 200%, preferably 100 to 150% (% by weight) based on the binder resin. If it is less than 50%, the effect of addition is not exhibited, and if it exceeds 200%, it causes the generation of print dust, which is not preferable.

The amount of the protective layer deposited is 0.5 g / m ² to 4.
It is preferably 0 g / m ² . The adhesion amount of the protective layer is
If it is less than 0.5 g / m ² , it is not effective because it cannot absorb the hot melt. If it exceeds 4.0 g / m ² ,
Due to the concealing effect, a color image and a decrease in sensitivity are seen. Further, if necessary, auxiliary components commonly used in this type of heat-sensitive recording material may be added to the protective layer in the present invention, for example, a surfactant, a lubricant, a pressure color-developing preventing agent and the like.

Particularly, fatty acids such as stearic acid and behenic acid, fatty acid amides such as stearic acid amide and palmitic acid amide, zinc stearate, aluminum stearate and calcium stearate can be prepared by lowering the friction coefficient of the protective layer. In addition, it is preferable to add it because the effects of improving running property and improving sticking can be seen.

As the heat-sensitive color developing layer in the heat-sensitive recording material of the present invention, a conventionally known heat-sensitive color developing layer can be used. A colorless or light-colored leuco dye and a color developer that develops a color upon contact with the leuco dye are used. A thermosensitive coloring layer containing the main component is preferable. Examples of such leuco dyes include:
Triphenylmethanephthalide type, triallylmethane type,
Fluoran-based, phenothidian-based, thioferoral-based, methine-based, rhodamine-anilinolactam-based, rhodamine-lactam-based, quinazoline-based, diazaxanthene-based,
Leuco compounds such as bislactones are preferable, and these are used alone or in admixture of two or more.

Specific examples of such a compound include those shown below. 3,3-bis (P-
Dimethylaminophenyl) -phthalide, 3,3-bis (P-dimethylaminophenyl) -6-dimethylaminophthalide, 3,3-bis (P-dimethylaminophenyl) -6-diethylaminophthalide, 3,3- Screw (P
-Dimethylaminophenyl) -6-chlorophthalide,
3,3-bis (P-dimethylaminophenyl) phthalide, 3-cyclohexialamino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3- (N-methyl-N-isoamylamino) ) -6-
Methyl-7-anilinofluorane, 3- (N-ethyl-
N-isobutylamino) -6-methyl-7-anilinofluorane, 3- (NP-tolyl-N-ethylamino)
-6-Methyl-7-anilinofluorane, 3- (N-methyl-N-amylamino) -6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexylamino) -6- Methyl-7-anilinofluorane, 3-
(N-methyl-N-isopropylamino) -6-methyl-7-anilinofluorane, 3- (N-methyl-N-tetrahydrofurylamino) -6-methyl-7-anilinofluorane, 3-diethylamino -7,8-benzfluorane, 3-diethylamino-7-chlorofluorane,
3-diethylamino-7-methylfluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-
Pyrrolidino-6-methyl-7-anilinofluorane, 3
-Diethylamino-6-methyl-7- (m-trichloromethylanilino) fluorane, 3-diethylamino-7
-(O-chloroanilino) fluorane, 3-dibutylamino-7- (o-chloroanilino) fluorane, 3-diethylamino-6-methyl-7-anilinofluorane,
3-dibutylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (2 ',
4'-dimethylanilino) fluorane, 3- (N, N-
Diethylamino) -5-methyl-7- (N, N-dibenzylamino) fluorane, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrrilospirane, 6'-bromo-3'-methoxy-
Benzindolino-pyrrilospirane, 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'-dimethylaminophenyl) -3- (2'-methoxy-5'-methylphenyl) phthalide, 3 -(2'-Methoxy-4'-dimethylaminophenyl) -3- (2'-hydroxy-4'-
Chlor-5'-methylphenyl) phthalide, 3-morpholino-7- (N-propyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro. -7- (N-benzyl-trifluoromethylanilinofluorane, 3-pyrrolidino-7- (di-P-chlorophenyl) methylaminofluorane, 3-diethylamino-5-chloro-7- (α-phenylethyl) Amino) 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, 3,6-bis (dimethylamino) fluorenebispyro (9,3 ′)-6′-dimethylaminophthalide, 3- (N -Benzyl-N-cyclohexylamino) -5,6-benzo-7-α-naphthylamino-4'bromofluorane, 3-diethylamino-6-
Chlor-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'-benzoyloxy) -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-dibromophthalide, bis (P-dimethylaminostyryl) -1-naphthalenesulfonylmethane, bis (P-dimethylaminostyryl) -1-P-tolylsulfonylmethane and the like.

As the color developer, various electron-accepting compounds such as phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids, and metal salts thereof can be used. Examples include those shown below.

4,4'-isopropylidene bisphenol, 4,4'-isopropylidene bis (o-methylphenol), 4,4'-secondary butylidene bisphenol 4,4'-isopropylidene bis (2-tert-butylphenol) ) 4,4'-Methylenebis (oxyethylenethio) diphenol, 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'-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, isopropyl P-hydroxybenzoate, benzyl P-hydroxybenzoate, benzyl protocatechuylate, 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, 1-acetate Aryloxy-2-naphthoic acid zinc, 2-acetyloxy-1-naphthoic acid zinc, 2-
Zinc acetyloxy-3-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) international patent WO99 / 5
1444 (poly) 4-hydroxybenzoic acid derivative, international patent WO00 / 14058 urea urethane compound, JP-A-08-333329, etc. diphenyl sulfone derivative, sulfonylaminocarbonylamide group-containing color developer, etc. . The developer is used in an amount of 2 to 10 parts based on 1 part of the leuco dye.

In order to prepare a thermal paper having improved chemical resistance, a (poly) 4-hydroxybenzoic acid derivative, a urea urethane compound, a diphenyl sulfone derivative, 4,4 '
-The use of developers having dihydroxydiphenyl sulfone, sulfonylaminocarbonylamide groups is preferred.
The (poly) 4-hydroxybenzoic acid derivative is represented by the following formula (1).

[Chemical 1] (In the formula, n represents a number of 0 to 2) The urea urethane compound is represented by the following formula (2).

[Chemical 2] (In the formula, R1, R2, and R3 each independently represent a substituent.) The diphenyl sulfone derivative is represented by the following formula (4).

[Chemical 3] (In the formula, Ph represents a P-phenylene group, and n is 1 to 12
Number, preferably 3 to 10)

Further, in the present invention, various heat fusible substances can be used in combination as the sensitivity improving agent, and specific examples thereof include the following. 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-
Benzylbiphenyl, terphenyl, triphenylmethane, benzyl P-benzyloxybenzoate, β-benzyloxynaphthalene, phenyl β-naphthoate, phenyl 1-hydroxy-2-naphthoate, 1-hydroxy-
2-methyl 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-diphenoxybutane, 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-aryloxy Biphenyl, P-propargyloxybiphenyl, dibenzoyloxymethane, dibenzoyloxypropane, dibenzyldisulfide, 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- (4-methoxyphenoxy) -3-oxapentane, dibenzyl oxalate, bis (4-methylbenzyl) oxalate, bis (4-chlorobenzyl oxalate)
Such.

As the support in the present invention, high-quality paper,
A support made of waste paper pulp (50% or more of waste paper pulp is used), synthetic paper, laminated paper and the like can be used.

Further, an undercoat layer between the support and the thermosensitive recording layer or an overcoat layer may be provided on the thermosensitive recording layer. As the material for forming the undercoat layer or the overcoat layer, the binder, filler, cross-linking agent or the like used in the heat-sensitive recording layer can be used. It is particularly preferable to use hollow resin particles as a filler in the undercoat layer because the heat insulating property can improve the sensitivity. Further, the hollow particles used in the present invention, a thermoplastic resin as a shell, which contains air or other gas inside, is a hollow microparticles already in a foamed state,
Those having an average particle diameter of 2 to 10 μm are used. The average particle size (particle outer diameter) smaller than 2 μm is
On the other hand, there is a production problem such that it is difficult to achieve an arbitrary hollow ratio. On the contrary, when the hollowness is larger than 10 μm, the smoothness of the surface after coating and drying is deteriorated, the adhesion with the thermal head is deteriorated, and the sensitivity is lowered. The improvement effect decreases. Therefore, such a particle distribution is preferably such that the particle diameter is within the above range and the distribution peaks are uniform with little variation. Further, the hollow microparticles used in the present invention preferably have a hollowness of 50% or more, more preferably 70% or more.
The hollow ratio mentioned here is the ratio of the outer diameter to the inner diameter of the hollow particles and is represented by the following formula.

## EQU1 ## Hollow ratio = (inner diameter of hollow particles) / (outer diameter of hollow particles) × 100 (1) The fine hollow particles used in the present invention have a shell of a thermoplastic resin as described above. Examples of the resin include polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyacrylic acid ester, polyacrylonitrile, polybutadiene, and copolymer resins thereof. A copolymer resin mainly containing vinylidene chloride and acrylonitrile is particularly preferable. Normal,
When the hollow particles are used as an intermediate layer between the thermosensitive coloring layer and the support, high heat insulating property and adhesion to the head are improved, and coloring sensitivity is improved.

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 and the like depending on the purpose of use.

A conventionally known method may be used to form the thermosensitive coloring layer and the protective layer on the support, and the thermosensitive coloring layer coating solution and the protective layer coating solution are sequentially coated on the support. It can be dried. The coating solution for the heat-sensitive color forming layer and the coating solution for the protective layer include blade coating method, air knife coating method, gravure coating method, roll coating coating method, spray coating method, dip coating method, bar coating method, extrusion coating. A conventionally known coating method such as a method can be used.

[0031]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, all parts and% in the examples are parts by weight and% by weight.

Example 1 (1) Preparation of Dye Dispersion (Liquid A) 3-Dibutylamino-6-methyl-N-7-anilinofluorane 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts water 60 parts The composition is sand-milled to have an average particle size of 0.5 μm.
The resulting mixture was dispersed until it became a liquid A.

(2) Preparation of Solution B A developer (30 parts by weight), calcium carbonate 10 parts, 10% aqueous solution of polyvinyl alcohol 20 parts water 40 parts, and a composition having an average particle size of 0.5 μm in a ball mill.
The solution B was dispersed until

Type of developer shown in Table 1: (2) -1: 4-isopropoxy-4'-hydroxydiphenyl sulfone (2) -2: 4-hydroxybenzoic acid polyester (Asahi Denka Kogyo KK) K-5 manufactured by (2) -3: urethane urea compound (U manufactured by Asahi Kasei Corporation)
D) (2) -4: Diphenylsulfonic acid derivative (D-90 manufactured by Nippon Soda Co., Ltd.) (2) -5: Compound having a sulfonylaminocarbonylamide group (pergafast 201 manufactured by Ciba Specialty Chemicals Co., Ltd.) (2) -6: 4,4'-dihydroxydiphenyl sulfone (bisphenol S)

(3) Preparation of thermosensitive color developing layer coating solution 20 parts of solution A, 60 parts of solution B 30 parts of carboxy group-modified PVA (solid content: 10%), 1 part of dioctylsulfosuccinic acid aqueous solution (solid content: 5%) 1 part Was mixed to prepare a thermosensitive color developing layer coating liquid.

[0036] (4) Preparation of protective layer coating liquid     Silica dispersion (oil absorption: listed in Table 1, water dispersion: 1 hour,         Solid content: 50%) X part     Aqueous resin solution (described in Table 1, solid content 10%) 100 parts     Dioctyl sulfosuccinic acid aqueous solution (solid content; 5%) 1 part     Crosslinking agent aqueous solution (solid content; 10%) 10 parts     20 parts of release agent (described in Table 1) The composition consisting of was mixed to prepare a protective layer coating liquid.

(5) Preparation of Undercoat Layer Forming Liquid (5) -1 Calcined Kaolin: 20 parts Styrene / butadiene copolymer latex (solid content concentration 47.5%): 20 parts Water: 60 parts (5) -2 Hollow resin particles (hollowness 90%, average particle size 3.5 μm, solid content 40%): 25 parts Styrene / butadiene copolymer latex (solid content concentration 47.5%): 15 parts Water: 60 parts Stir the above mixture An undercoat layer forming liquid was prepared by dispersion.

Preparation of thermal recording paper: An undercoat solution shown in Table 1 was coated on a paper having a basis weight of 60 g / m ^{2 so} that the dry coating amount was 3.0 g / m ² and dried. Then, a thermosensitive coloring solution was applied on top of it, and the amount of dye deposited was 0.45 g /
m ² was applied and dried, and a protective layer coating solution was further applied thereon so that the amount of the protective layer adhered was 1.5 g / m ² , and dried (the amount of adhered is the amount of dried adhered). After processing with a super calender, the heat-sensitive recording material papers described in Examples and Comparative Examples in Table 1 were obtained.

[0039]

[Table 1]

In the release agent shown in Table 1, SM700
1 and SM7002 are hydrocarbon group-modified silicone oil emulsions manufactured by Toray Dow Corning Silicone Co., Ltd. SH7036 shown in Table 1 is S
Both H7024 and SH7706 are non-hydrocarbon modified silicone oil emulsions manufactured by the same company.

<Evaluation method for thermal recording paper> (1) Sensitivity magnification; calendered product was used in a thermal printing experimental apparatus having a thin film head manufactured by Matsushita Electric Parts Co., Ltd., head power 0.45 W / dot 1 line recording time. 20 ms
ec / L, scanning density 8 × 385 dots / mm,
A pulse width of 0.0 to 0.7 mmsec was printed every 1 msec, the print density was measured with a Macbeth densitometer RD-914, and the pulse width at which the density became 1.0 was calculated. Comparative example-
Using 1 as a reference, (pulse width of Comparative Example-1) / (pulse width of measured sample) = sensitivity magnification is calculated. The larger the value, the better the sensitivity (thermal response). (2) Image density: The calendered product was printed with a pulse width of 0.5 mmsec using the thermal printing experimental device described above, and the print density and background density were measured with a Macbeth densitometer RD-914. (3) Evaluation of sticking property under low temperature and low humidity conditions Each thermal recording material and handy printer (type FHT205B, manufactured by Fujitsu Ltd.) were stored at -5 ° C. and 20% RH.
After being left in the low temperature and low humidity environment for 1 hour to adjust the humidity, printing was performed (printing conditions were mode printing). The print length is the print length from the print start part to the print last part when a specific print pattern is printed by the printer, whereas if the sticking property is excellent, the print pattern is printed accurately. If the sticking property is inferior, the same part of the heat-sensitive recording material is overprinted, and meandering of the heat-sensitive recording material occurs. The print length will be shorter than the print length. Further, the print quality was visually confirmed, and the sticking was evaluated according to the following criteria. (Visual evaluation of sticking) ◎ No sticking occurred. ○: There is a slight occurrence of stacking. △ …… Sticking occurred slightly. × ・ ・ ・ Sticking occurred quite often.

[0042]

[Table 2]

As is clear from the results shown in Table 2, the thermosensitive recording material of the present invention has good sticking property at low temperature and low humidity and excellent color density / sensitivity.

[0044]

According to the heat-sensitive recording material of the present invention, in the heat-sensitive recording material having a protective layer containing a binder resin, a crosslinking agent, a filler and a releasing agent, the releasing agent is a hydrocarbon group-modified silicone oil. By using it, it is possible to perform heat-sensitive recording which is excellent in head matching property even under low temperature and low humidity conditions and is also excellent in color image / sensitivity.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H026 AA07 BB24 BB26 BB28 BB30                       DD08 DD32 DD42 DD48 DD55                       DD56 FF01 FF11 FF13

Claims (7)

[Claims] 1. A heat-sensitive recording material comprising a support and a heat-sensitive coloring layer which is colored by heat, and a protective layer containing a binder resin, a cross-linking agent, a filler and a releasing agent on the heat-sensitive coloring layer. In the heat-sensitive recording material, the release agent is a hydrocarbon group-modified silicone oil. 2. The binder resin is polyvinyl alcohol containing a reactive carbonyl group.
The heat-sensitive recording material described in. 3. The heat-sensitive recording material according to claim 1, wherein the crosslinking agent is a hydrazide compound. 4. The oil absorption of the filler is 50 ml / 10.
The heat-sensitive recording material according to any one of claims 1 to 3, wherein the heat-sensitive recording material is 0 g to 200 ml / 100 g. 5. The filler is 100 to 100 relative to the binder resin.
It is 500%, The thermal recording material in any one of Claims 1-4. 6. The thermosensitive recording material according to claim 1, wherein an intermediate layer containing thermoplastic hollow resin particles is provided between the support and the thermosensitive coloring layer. 7. The thermosensitive coloring layer is selected from the group consisting of (poly) 4-hydroxybenzoic acid derivatives, urea urethane compounds, diphenylsulfonic acid derivatives, compounds having a sulfonylaminocarbonylamide group and 4,4′-dihydroxydiphenylsulfone. 7. The heat-sensitive recording material according to claim 1, containing at least one developer selected.