JP3496799B2 - Thermal recording medium - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosensitive recording medium utilizing a color-forming reaction between an electron-donating color-forming compound and an electron-accepting compound, and more particularly to a film for a video printer,
The present invention relates to a transparent thermosensitive recording medium useful as an image forming film sheet for an overhead projector and a CAD image forming film sheet.

[0002]

2. Description of the Related Art Conventionally, electron-donating color-forming compounds (hereinafter referred to as
A heat-sensitive recording medium utilizing a color-forming reaction between a color former and an electron-accepting compound (hereinafter also referred to as a developer) is widely known. In recent years, the usage has been expanded and there is a demand for an overhead projector, a second original drawing of a diazo copying system, and a design drawing.

As a transparent thermosensitive recording medium which can be directly recorded by a thermal head, Japanese Patent Application No. 61-2187 is available.
There is one proposed in Japanese Patent No. 5 and Japanese Patent Application Laid-Open No. 1-99873. However, in order to produce these transparent heat-sensitive recording media, a color-forming agent is microencapsulated, and a developer consisting of an emulsified dispersion prepared by emulsifying and dispersing a color-developing agent dissolved in an organic solvent that is hardly soluble or insoluble in water. There is a problem in production such as a fairly complicated process such as applying a liquid to a transparent support to prepare it, and there is also a problem that transparency is insufficient. There is also a problem that the thermal transfer printer for printing cannot sufficiently print.

Recently, thermal sensitivity and color image density have improved,
Furthermore, runnability and sticking (head matching)
A transparent heat-sensitive recording medium which is excellent in transparency, can be easily manufactured, and has excellent transparency has been proposed (Japanese Patent Laid-Open No. 5-104859). However, this transparent thermosensitive recording medium has a problem in the adhesiveness between the transparent support and the thermosensitive recording layer, and when the transparent thermosensitive recording medium is cut with a cutter or the like, there is a problem that the recording layer peels from the cut end. .

To solve this problem, Japanese Patent Laid-Open No. 7-10
In 8763, the adhesiveness is improved by the method of providing the adhesive layer, but there is a problem that the manufacturing cost is increased by forming the adhesive layer. Further, this transparent thermosensitive recording medium also has a problem in flexibility, and when the transparent thermosensitive recording medium is bent, there is a problem that the recording layer is cracked and becomes cloudy.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above problems found in the prior art in a transparent thermosensitive recording medium utilizing the reaction between a color former and a color developer, and has a thermal sensitivity and a color image. Higher density, more excellent running property, sticking property (head matching property), adhesiveness between support and recording layer, flexibility, easy production, and transparent heat sensitivity. The purpose is to provide a recording medium.

[0007]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have found that polyester film
On a transparent support comprising a beam, a leuco dye, a recording layer composed of a binder resin as a color developer and a binder allowed to heat coloring the leuco dye is formed directly, further the recording
It is a transparent thermosensitive recording medium having a protective layer formed on the layer.
And the binder resin contained in the recording layer is polyester.
Urethane and the polyester urethane is 2 or more
Polybasic acid having a carboxyl group and dihydric alcohol
The saturated polyester obtained by the condensation reaction of
A molecule obtained by reacting a cyanate with a chain extender
The inventors have found that an elastomer having a urethane bond in the chain is effective for the adhesiveness and flexibility of the support and the recording layer, and completed the present invention. It has also been found that the content of polyester urethane in the binder resin is particularly preferably 15% or more. Further, a polyester film whose surface is subjected to corona discharge treatment is particularly preferable in terms of adhesiveness with the recording layer. The present invention will be described in more detail below. A polyester urethane resin is used for the binder of the recording layer of the heat-sensitive recording medium in the present invention for the purpose of improving the adhesiveness and flexibility between the support and the recording layer.

The polyester urethane in the present invention is
An elastomer having a urethane bond in the molecular chain,
Usually, a saturated polyester obtained by a condensation reaction of a polybasic acid having two or more carboxyl groups and a dihydric alcohol can be obtained by reacting an organic diisocyanate and a chain extender.

Examples of the polybasic acid include adipic acid, azelaic acid, sebacic acid, dodecanoic acid, terephthalic acid, isophthalic acid, phthalic acid, succinic acid, orthophthalic acid,
2,3-naphthalic acid, 1,1,3-trimethyl-3-phenylindene-4′5-dicarboxylic acid, 5-sodiumsulfoisophthalic acid, naphthalenedicarboxylic acid and the like can be mentioned.

Examples of the dihydric alcohol include ethylene glycol, propylene glycol, neopentyl glycol, diethylene glycol, dipropylene glycol, polyethylene glycol, tripropylene glycol, 2,3,4-trimethylol-1,3-pentanediol, 1 , 6-hexanediol, bisphenol A
Ethylene oxide adduct, hydrogenated bisphenol A
Ethylene oxide and / or propylene oxide adduct, 2,2-diethyl-1,3-propanediol, 2-n-butyl-2-ethyl-1,3-propanediol, tricyclodecanedimethylol, cyclohexanediol, etc. Is mentioned.

As the organic diisocyanate used,
Hexamethylene diisocyanate, tetramethylene diisocyanate, 3,3-dimethoxy-4,4'-biphenylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, 1,3-diisocyanate-methylcyclohexane, 1,4-diisocyanate methylcyclohexane , 4,4-diisocyanate dicyclohexane, 4,4-diisocyanate cyclohexylmethane, isophorone diisocyanate,
2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, p-phenylene diisocyanate,
Diphenylmethane diisocyanate, m-phenylene diisocyanate, 2,4-naphthalene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 4,4'-diisocyanate biphenyl ether, 1,5'-naphthalene diisocyanate and the like can be mentioned. . Preferred among these are hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate and diphenylmethane diisocyanate.

Examples of the chain extender include ethylene glycol, propylene glycol, neopentyl glycol, 2,2-diethyl-1,3-propanediol, polyethylene glycol, diethylene glycol, polypropylene glycol, polytetramethylene glycol,
Examples include tricyclodecane dimethylol, bisphenol A ethylene oxide adduct, 1,4-cyclohexanedimethanol and the like. Among them, neopentyl glycol, ethylene glycol, polyethylene glycol, diethylene glycol and bisphenol A ethylene oxide adduct are more preferable.

The polyester urethane resin is produced by a known method, for example, in a solvent at a reaction temperature of 20 to 150 ° C. in the presence of a catalyst or without a catalyst. Examples of the solvent used at this time include ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; aromatic hydrocarbons such as toluene and xylene; and esters such as ethyl acetate and butyl acetate. In addition, amines, organotin compounds and the like are used as catalysts for promoting the reaction.

These polyester urethane resins may be used alone or in combination of two or more. Furthermore, transparency,
In order to improve the gradation of the image and the like, a conventionally known binder resin can be mixed if necessary. Examples of these resins include polyacrylamide, maleic acid copolymer, polyacrylic acid ester, polymethacrylic acid ester, vinyl chloride / vinyl acetate copolymer, styrene copolymer, polyester, polyurethane, polyvinyl butyral, ethyl cellulose. , Polyvinyl acetal, polyvinyl acetoacetal, polycarbonate,
An epoxy resin, polyamide, etc. can be mentioned. The content of polyester urethane in the binder resin is 15
% Or more is preferable. If the content of the polyester urethane is less than 15%, the adhesiveness to the support may be reduced.

The leuco dye used in the present invention is a compound exhibiting an electron-donating property, and is applied alone or as a mixture of two or more kinds, but it is a colorless or light-colored dye precursor per se and is not particularly limited and is conventionally. Known compounds, for example, triphenylmethanephthalide-based, triallylmethane-based, fluorane-based, phenothidian-based, thioferolane-based, xanthene-based, indophthalyl-based, spiropyran-based, azaphthalide-based, chromenopyrazole-based, methine-based, rhodamine Leuco compounds such as anilinolactam type, rhodamine lactam type, quinazoline type, diazaxanthene type and bislactone type are preferably used. Examples of such compounds include those shown below.

2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-
(Di-n-butylamino) fluorane, 2-anilino-
3-Methyl-6- (Nn-propyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (N
-Isopropyl-N-methylamino) fluorane, 2-
Anilino-3-methyl-6- (N-isobutyl-N-methylamino) fluorane, 2-anilino-3-methyl-
6- (Nn-amyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (N-sec-butyl-N-ethylamino) fluorane, 2-anilino-
3-Methyl-6- (Nn-amyl-N-ethylamino) fluorane, 2-anilino-3-methyl-6- (N
-Isoamyl-N-ethylamino) fluorane, 2-anilino-3-methyl-6- (Nn-propyl-N-isopropylamino) fluorane, 2-anilino-3-methyl-6- (N-cyclohexyl-N -Methylamino)
Fluoran,

2-anilino-3-methyl-6- (N-ethyl-p-toluidino) fluorane, 2-anilino-3
-Methyl-6- (N-methyl-p-toluidino) fluorane, 2- (m-trichloromethylanilino) -3-methyl-6-diethylaminofluorane, 2- (m-trifluoromethylanilino) -3 -Methyl-6-diethylaminofluorane, 2- (m-trifluoromethylanilino) -3-methyl-6- (N-cyclohexyl-N-methylamino) fluorane, 2- (2,4-dimethylanilino) -3-methyl-6-diethylaminofluorane,
2- (N-ethyl-p-toluidino) -3-methyl-6
-(N-ethylanilino) fluorane, 2- (N-methyl-p-toluidino) -3-methyl-6- (N-propyl-p-toluidino) fluorane, 2-anilino-6-
(Nn-hexyl-N-ethylamino) fluorane,
2- (o-chloroanilino) -6-diethylaminofluorane, 2- (o-bromoanilino) -6-diethylaminofluorane, 2- (o-chloroanilino) -6-dibutylaminofluorane,

2- (o-Fluoroanilino) -6-dibutylaminofluorane, 2- (m-trifluoromethylanilino) -6-diethylaminofluorane, 2- (p-
Acetylanilino) -6- (Nn-amyl-Nn-
Butylamino) fluorane, 2-benzylamino-6-
(N-Ethyl-p-toluidino) fluorane, 2-benzylamino-6- (N-methyl-2,4-dimethylanilino) fluorane, 2-benzylamino-6- (N-ethyl-2,4-dimethyl) Anilino) fluorane, 2-dibenzylamino-6- (N-methyl-p-toluidino)
Fluorane, 2-dibenzylamino-6- (N-ethyl-p-toluidino) fluorane, 2- (di-p-methylbenzylamino) -6- (N-ethyl-p-toluidino) fluorane, 2- (α -Phenylethylamino)-
6- (N-ethyl-p-toluidino) fluorane, 2-
Methylamino-6- (N-methylanilino) fluorane, 2-methylamino-6- (N-ethylanilino) fluorane, 2-methylamino-6- (N-propylanilino) fluorane, 2-ethylamino-6- ( N-methyl-p-toluidino) fluorane, 2-methylamino-
6- (N-methyl-2,4-dimethylanilino) fluorane,

2-ethylamino-6- (N-methyl-
2,4-dimethylanilino) fluorane, 2-dimethylamino-6- (N-methylanilino) fluorane, 2-
Dimethylamino-6- (N-ethylanilino) fluorane, 2-diethylamino-6- (N-methyl-p-toluidino) fluorane, 2-diethylamino-6- (N-
Ethyl-p-toluidino) fluorane, 2-dipropylamino-6- (N-methylanilino) fluorane, 2-
Dipropylamino-6- (N-ethylanilino) fluorane, 2-amino-6- (N-methylanilino) fluorane, 2-amino-6- (N-ethylanilino) fluorane, 2-amino-6- (N-propylanim Rhino) fluorane, 2-amino-6- (N-methyl-p-toluidino) fluorane, 2-amino-6- (N-ethyl-p-
Toluidino) fluorane, 2-amino-6- (N-propyl-p-toluidino) fluorane, 2-amino-6-
(N-methyl-p-ethylanilino) fluorane, 2-
Amino-6- (N-ethyl-p-ethylanilino) fluorane, 2-amino-6- (N-propyl-p-ethylanilino) fluorane, 2-amino-6- (N-methyl-2,4-dimethylanilino) ) Fluorane, 2-amino-6- (N-ethyl-2,4-dimethylanilino) fluorane, 2-amino-6- (N-propyl-2,4-dimethylanilino) fluorane,

2-amino-6- (N-methyl-p-chloranilino) fluorane, 2-amino-6- (N-ethyl-p-chloroanilino) fluorane, 2-amino-6
-(N-propyl-p-chloroanilino) fluorane,
2,3-Dimethyl-6-dimethylaminofluorane 3-
Methyl-6- (N-ethyl-p-toluidino) fluorane, 2-chloro-6-diethylaminofluorane, 2-
Bromo-6-diethylaminofluorane, 2-chloro-
6-dipropylaminofluorane, 3-chloro-6-cyclohexylaminofluorane, 3-bromo-6-cyclohexylaminofluorane, 2-chloro-6- (N-
Ethyl-N-isoamylamino) fluorane, 2-chloro-3-methyl-6-diethylaminofluorane, 2-
Anilino-3-chloro-6-diethylaminofluorane, 2- (o-chloroanilino) -3-chloro-6-cyclohexylaminofluorane, 2- (m-trifluoromethylanilino) -3-chloro-6-diethylamino Fluorane, 2- (2,3-dichloroanilino) -3-chloro-6-diethylaminofluorane, 1,2-benzo-6-diethylaminofluorane, 1,2-benzo-6
-(N-ethyl-N-isoamylamino) fluorane,
1,2-benzo-6-dibutylaminofluorane, 1,
2-benzo-6- (N-ethyl-N-cyclohexylamino) fluorane, 1,2-benzo-6- (N-ethyl-toluidino) fluorane, and others.

Specific examples of other color formers preferably used in the present invention are as follows. 2-anilino-3-methyl-6- (N-2-ethoxypropyl-N
-Ethylamino) fluorane, 2- (p-chloroanilino) -6- (Nn-octylamino) fluorane, 2
-(P-chloranilino) -6- (N-n-partimilylamino) fluorane, 2- (p-chloranilino) -6
-(Di-n-octylamino) fluorane, 2-benzoylamino-6- (N-ethyl-p-toluidino) fluorane, 2- (o-methoxybenzoylamino) -6-
(N-ethyl-p-toluidino) fluorane, 2-dibenzylamino-4-methyl-6-diethylaminofluorane, 2-dibenzylamino-4-methoxy-6- (N
-Methyl-p-toluidino) fluorane, 2-dibenzylamino-4-methyl-6- (N-ethyl-p-toluidino) fluorane, 2- (α-phenylethylamino)
-4-Methyl-6-diethylaminofluorane, 2-
(P-Toluidino) -3- (t-butyl) -6- (N-
Methyl-p-toluidino) fluorane,

2- (o-methoxycarbonylanilino)
-6-diethylaminofluorane, 2-acetylamino-6- (N-methyl-p-toluidino) fluorane, 3
-Diethylamino-6- (m-trifluoromethylanilino) fluorane, 4-methoxy-6- (N-ethyl-
p-toluidino) fluorane, 2-ethoxyethylamino-3-chloro-6-dibutylaminofluorane, 2-
Dibenzylamino-4-chloro-6- (N-ethyl-p
-Toluidino) fluorane, 2- (α-phenylethylamino) -4-chloro-6-diethylaminofluorane, 2- (N-benzyl-p-trifluoromethylanilino) -4-chloro-6-diethylaminofluorane Two
-Anilino-3-methyl-6-pyrrolidinofluorane,
2-anilino-3-chloro-6-pyrrolidinofluorane, 2-anilino-3-methyl-6- (N-ethyl-N
-Tetrahydrofurfurylamino) fluorane, 2-mesitidino-4 ', 5'-benzo-6-diethylaminofluorane, 2- (m-trifluoromethylanilino) -3
-Methyl-6-pyrrolidinofluorane, 2- (α-naphthylamino) -3,4-benzo-4'-bromo-6-
(N-benzyl-N-cyclohexylamino) fluorane, 2-piperidino-6-diethylaminofluorane,

2- (N-n-propyl-p-trifluoromethylanilino) -6-morpholinofluorane, 2-
(Di-Np-chlorophenyl-methylamino) -6-
Pyrrolidinofluorane, 2- (N-n-propyl-m-
Trifluoromethylanilino) -6-morpholinofluorane, 1,2-benzo-6- (N-ethyl-Nn-octylamino) fluorane, 1,2-benzo-6-diallylaminofluorane, 1 , 2-benzo-6- (N-ethoxyethyl-N-ethylamino) fluorane, benzoleucomethylene blue 2- {3,6-bis (diethylamino)}-6- (o-
Chloranilino) xanthyl lactam benzoate, 2-
{3,6-bis (diethylamino)}-9- (o-chloroanilino) xanthyl benzoate lactam, 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- (2-methoxy-4)
-Dimethylaminophenyl) -3- (2-hydroxy-
4,5-dichlorophenyl) phthalide, 3- (2-hydroxy-4-dimethylaminophenyl) -3- (2-methoxy-5-chlorophenyl) phthalide, 3- (2-hydroxy-4-dimethoxyaminophenyl) ) -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,
3,6-bis (dimethylamino) fluorene spiro (9,3 ′)-6′-dimethylaminophthalide, 6′-
Chloro-8'-methoxy-benzoindolino-spiropyran, 6'-bromo-2'-methoxy-benzoindolino-spiropyran and the like.

Next, the color developing agent used in the present invention is an electron-accepting compound, and various conventionally known electron-accepting color developing agents can be used, but the more preferable one in the present invention is It is an electron-accepting color developer containing a long-chain alkyl group in the molecule, which is disclosed in, for example, Kaihei 5-124360.
For example, an organic phosphoric acid compound, an aliphatic carboxylic acid compound or a phenol compound having an aliphatic group having 12 or more carbon atoms, or a metal salt of mercaptoacetic acid having an aliphatic group having 10 to 18 carbon atoms, or 5 to 8 carbon atoms. And an alkyl ester of caffeic acid having an alkyl group, an acidic phosphoric acid ester having an aliphatic group having 16 or more carbon atoms, and the like. The aliphatic group includes a linear or branched alkyl group and alkenyl group,
It may have a substituent such as a halogen, an alkoxy group or an ester. Specific examples of the developer will be illustrated below. (A) Organic Phosphoric Acid Compound In the present invention, an organic phosphoric acid compound represented by the following general formula (1) is preferably used.

[0026]

[Chemical 1] (R ₁ represents a linear alkyl group having 12 or more carbon atoms) Specific examples of the organic phosphoric acid compound represented by the general formula (1) include the following. Dodecylphosphonic acid, tetradecylphosphonic acid, hexadecylphosphonic acid, octadecylphosphonic acid, eicosylphosphonic acid, docosylphosphonic acid, tetracosylphosphonic acid, hexacosylphosphonic acid, octacosylphosphonic acid and the like. As the organic phosphoric acid compound, α-hydroxyalkylphosphonic acid represented by the following general formula (2) is also preferably used.

[0027]

[Chemical 2] (However, R ₂ is an aliphatic group having 11 to 29 carbon atoms.) Specific examples of the α-hydroxyalkylphosphonic acid represented by the general formula (2) include α-hydroxydodecylphosphonic acid and α-hydroxytetracarboxylic acid. Decylphosphonic acid, α-
Examples thereof include hydroxyhexadecylphosphonic acid, α-hydroxyoctadecylphosphonic acid, α-hydroxyeicosylphosphonic acid, α-hydroxydocosylphosphonic acid, and α-hydroxytetracosylphosphonic acid. Also,
As the organic phosphoric acid compound, an acidic organic phosphoric acid ester represented by the following general formula (3) is also preferably used.

[0028]

[Chemical 3] (In the formula, R ₃ represents an aliphatic group having 16 or more carbon atoms, and R ₄ represents a hydrogen atom or an aliphatic group having 1 or more carbon atoms.) An acidic organic phosphate ester represented by the general formula (3) Specifically, dihexadecyl phosphate, dioctadecyl phosphate, dieicosyl phosphate, didocosyl phosphate, monohexadecyl phosphate,
Examples include monooctadecyl phosphate, monoeicosyl phosphate, monodocosyl phosphate, methyl hexadecyl phosphate, methyl octadecyl phosphate, methyl eicosyl phosphate, methyl docosyl phosphate, amyl hexadecyl phosphate, octyl hexadecyl phosphate, and lauryl hexadecyl phosphate. To be

(B) Aliphatic carboxylic acid compound In the present invention, as the aliphatic carboxylic acid compound, α-hydroxy fatty acids represented by the following general formula (4) are preferably used.

[0030]

[Chemical 4] (However, R ₅ represents an aliphatic group having 12 or more carbon atoms.) Examples of the α-hydroxy aliphatic carboxylic acid compound represented by the general formula (4) include the following.
α-hydroxydecanoic acid, α-hydroxytetradecanoic acid, α-hydroxyhexadecanoic acid, α-hydroxyoctadecanoic acid, α-hydroxypentadecanoic acid, α-hydroxyeicosanoic acid, α-hydroxydocosanoic acid, α
-Hydroxytetracosanoic acid, α-hydroxyhexacosanoic acid, α-hydroxyoctacosanoic acid and the like.

As the aliphatic carboxylic acid compound,
An aliphatic carboxylic acid compound having an aliphatic group having 12 or more carbon atoms which is substituted with a halogen element and having a halogen element at at least the α-position or β-position carbon is also preferably used. Specific examples of such a compound include the followings. 2-bromohexadecanoic acid, 2-bromoheptadecanoic acid, 2-bromooctadecanoic acid, 2-bromoeicosanoic acid, 2-bromodocosanoic acid, 2-bromotetracosanoic acid, 3-bromooctadecanoic acid, 3-bromoeicosanoic acid 2,3-dibromooctadecanoic acid, 2-fluorododecanoic acid, 2-fluorotetradecanoic acid, 2-fluorohexadecanoic acid, 2-fluorooctadecanoic acid, 2-fluoroeicosanoic acid, 2-
Fluorodocosanoic acid, 2-iodohexadecanoic acid, 2-
Iodooctadecanoic acid, 3-iodohexadecanoic acid, 3
-Iodooctadecanoic acid, perfluorooctadecanoic acid and the like.

The aliphatic carboxylic acid is an aliphatic carboxylic acid compound having an aliphatic group having 12 or more carbon atoms and having an oxo group in the carbon, and at least the carbon at the α-position, β-position or γ-position is oxo. The base material is also preferably used. Specific examples of such a compound include the followings. 2-oxododecanoic acid, 2-oxotetradecanoic acid, 2-oxohexadecanoic acid, 2-oxooctadecanoic acid, 2-oxoeicosanoic acid, 2-oxotetracosanoic acid, 3-oxododecanoic acid, 3-oxotetradecanoic acid, 3-oxohexadecanoic acid, 3-oxooctadecanoic acid, 3-oxoeicosanoic acid, 3-oxotetracosanoic acid, 4-oxohexadecanoic acid, 4-oxooctadecanoic acid, 4-oxodocosanoic acid and the like. Further, as the aliphatic carboxylic acid compound, a dibasic acid represented by the following general formula (5) is also preferably used.

[0033]

[Chemical 5] (However, R ₆ represents an aliphatic group having 12 or more carbon atoms,
X represents an oxygen atom or a sulfur atom, and n represents 1 or 2. Specific examples of the dibasic acid represented by the general formula (5) include:
For example: Dodecylmalic acid, tetradecylmalic acid, hexadecylmalic acid, octadecylmalic acid, eicosylmalic acid, docosylmalic acid, tetracosylmalic acid, dodecylthiomalic acid, tetradecylthiomalic acid, hexadecylthiomalic acid,
Octadecyl thiomalic acid, eicosyl thiomalic acid,
Docosylthiomalic acid, tetracosylthiomalic acid, dodecyldithiomalic acid, tetradecyldithiomalic acid,
Eicosyl dithiomalic acid, docosyl dithiomalic acid,
Tetracosyldithiomalic acid, etc. Furthermore, as the aliphatic carboxylic acid compound, a dibasic acid represented by the following general formula (6) is also preferably used.

[0034]

[Chemical 6] (However, R ₇ , R ₈ , and R ₉ represent hydrogen or an aliphatic group, at least one of which is an aliphatic group having 12 or more carbon atoms.) Specific examples of the dibasic acid represented by the general formula (6) For example,
For example: Dodecyl butanedioic acid,
Tridecyl butanedioic acid, tetradecyl butanedioic acid, pentadecyl butanedioic acid, octadecyl butanedioic acid, eicosyl butanedioic acid, docosyl butanedioic acid, 2,3-dihexadecyl butanedioic acid, 2,3-dioctadecyl Butanedioic acid, 2-methyl-3-dodecylbutanedioic acid, 2-methyl-3-tetradecylbutanedioic acid, 2-methyl-3-hexadecylbutanedioic acid, 2-ethyl-3-dodecylbutanedioic acid, 2-propyl-3-dodecylbutanedioic acid, 2-octyl-3-hexadecylbutanedioic acid, 2-tetradecyl-3-octadecylbutanedioic acid and the like. Furthermore, as the aliphatic carboxylic acid compound, a dibasic acid represented by the following general formula (7) is also preferably used.

[0035]

[Chemical 7] (However, R ₁₀ and R ₁₁ represent hydrogen or an aliphatic group, at least one of which is an aliphatic group having 12 or more carbon atoms.) Specific examples of the dibasic acid represented by the general formula (7) ,
For example, the following may be mentioned. Dodecylmalonic acid, tetradecylmalonic acid, hexadecylmalonic acid, octadecylmalonic acid, eicosylmalonic acid, docosylmalonic acid, tetracosylmalonic acid, didotecilmalonic acid,
Ditetradecylmalonic acid, dihexadecylmalonic acid, dioctadecylmalonic acid, dieicosylmalonic acid, didocosylmalonic acid, methyloctadecylmalonic acid, methyldocosylmalonic acid, methyltetracosylmalonic acid, ethyloctadecylmalonic acid, ethyl Eicosyl malonic acid, ethyl docosyl malonic acid, ethyl tetracosyl malonic acid, etc. Furthermore, as the aliphatic carboxylic acid compound, a dibasic acid represented by the following general formula (8) is also preferably used.

[0036]

[Chemical 8] (However, R ₁₂ represents hydrogen or an aliphatic group, n represents 0 or 1, m represents 1, 2 or 3, and when n is 0, m is 2 or 3 and n is 1 If m is 1 or 2
As a specific example of the dibasic acid represented by the general formula (8),
For example, the following may be mentioned. 2-dodecyl-
Pentanedioic acid, 2-hexadecyl-pentanedioic acid, 2-
Octadecyl pentanedioic acid, 2-eicosyl-pentanedioic acid, 2-docosyl-pentanedioic acid, 2-dodecyl-hexanedioic acid, 2-pentadecyl-hexanedioic acid, 2-octadecyl-hexanedioic acid, 2-eicosyl-hexane. Diacid, 2-docosyl-hexanedioic acid and the like. Furthermore, as the aliphatic carboxylic acid compound, a tribasic acid such as citric acid acylated with a long chain fatty acid is also preferably used. Specific examples thereof include the following. O-palmityl citric acid

[0037]

[Chemical 9] O-stearyl citric acid

[0038]

[Chemical 10] O-eicosyl enoic acid

[0039]

[Chemical 11] (C) Phenol compound In the present invention, a compound represented by the following general formula (9) is preferably used as the phenol compound.

[0040]

[Chemical 12] (However, Y is -S-, -O-, -CONH-, or -C.
OO-, R ₁₃ represents an aliphatic group having 12 or more carbon atoms, and n is an integer of 1, 2 or 3) Specific examples of the phenol compound represented by the general formula (9) are shown below. Something like this. p-
(Dodecylthio) phenol, p- (tetradecylthio) phenol, p- (hexadecylthio) phenol, p- (octadecylthio) phenol, p- (eicosylthio) phenol, p- (docosylthio) phenol, p- (tetracosylthio) Phenol, p- (dodecyloxy) phenol, p- (tetradecyloxy) phenol, p- (hexadecyloxy) phenol, p- (octadecyloxy) phenol, p- (eicosyloxy) phenol, p- (docosyloxy)
Phenol, p- (tetracosyloxy) phenol,
p-dodecylcarbamoylphenol, p-tetradecylcarbamoylphenol, p-hexadecylcarbamoylphenol, p-octadecylcarbamoylphenol, p-eicosylcarbamoylphenol, p-docosylcarbamoylphenol, p-tetracosylcarbamoylphenol, hexa gallic acid Decyl ester,
Gallic acid octadecyl ester, gallic acid eicosyl ester, gallic acid docosyl ester, gallic acid tetracosyl ester, etc. As the phenol compound, a caffeic acid alkyl ester represented by the following general formula (10) can also be used.

[0041]

[Chemical 13] (However, R ₁₄ is an alkyl group having 5 to 8 carbon atoms.) Specific examples of the caffeic acid alkyl ester represented by the general formula (10) include caffeic acid-n-ventil, caffeic acid-n-hexyl, and caffer. Acid-n-octyl etc. are mentioned. (D) Metal salt of mercaptoacetic acid In the present invention, a metal salt of an alkyl or alkenyl mercaptoacetic acid represented by the general formula (11) can be preferably used as the metal salt of mercaptoacetic acid.

[0042]

[Chemical 14] (However, R ₁₅ represents an aliphatic group having 10 to 18 carbon atoms, and M represents tin, magnesium, zinc, or copper.) Specific examples of the mercaptoacetic acid metal salt represented by the general formula (11) include the following. Something like.
Decylmercaptoacetic acid tin salt, dodecylmercaptoacetic acid tin salt, tetradecylmercaptoacetic acid tin salt, hexadecylmercaptoacetic acid tin salt, octadecylmercaptoacetic acid tin salt, decylmercaptoacetic acid megnesium salt, dodecylmercaptoacetic acid magnesium salt, tetradecylmercaptoacetic acid magnesium salt , Hexadecylmercaptoacetic acid magnesium salt, octadecylmercaptoacetic acid magnesium salt, decylmercaptoacetic acid zinc salt, dodecylmercaptoacetic acid zinc salt, tetradecylmercaptoacetic acid zinc salt, hexadecylmercaptoacetic acid zinc salt, octadecylmercaptoacetic acid zinc salt, decylmercaptoacetic acid copper salt Salt, dodecyl mercapto acetic acid copper salt, tetradecyl mercapto acetic acid copper salt, hexadecyl mercapto acetic acid copper salt, octadecyl mercapto acetic acid copper salt Etc..

Further, in the present invention, the color developer is not limited to the above compounds, and various other compounds having an electron accepting property can be used. In the heat-sensitive recording medium of the present invention, the color developer is 1 to 20 with respect to 1 part of the color developer.
Parts, preferably 2 to 10 parts are used. The color developer can be used 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.

The substrate of the heat-sensitive recording medium of the present invention is a transparent support, and polyester films such as polyethylene terephthalate and polybutylene terephthalate, cellulose derivative films such as cellulose triacetate, polypropylene,
It is common to use a polyolefin film such as polyethylene, a polystyrene film, or a transparent support obtained by laminating these. Among them, the polyester film is particularly preferable because it has mechanical strength, appropriate stiffness, heat resistance and solvent resistance, and has good adhesiveness to polyester urethane. When the polyester film is subjected to corona discharge treatment in order to improve the surface adhesiveness, a heat-sensitive recording medium having further excellent adhesiveness is provided.

In the transparent heat-sensitive recording layer of the present invention, only the color developer is uniformly dispersed in an organic solvent, and a color-developing agent and a binder resin are sequentially mixed to prepare a coating solution for the heat-sensitive recording layer, or an organic solvent is used. A developer is uniformly dispersed in a binder resin solution in which a binder resin is dissolved, and a thermosensitive recording layer is prepared by uniformly mixing a color former and the like, or a color developer and a developer together with a binder resin are combined with an organic solvent. It is prepared by uniformly dispersing the coating solution in the thermosensitive recording layer to prepare a coating solution for the thermosensitive recording layer, or by coating the coating solution uniformly dispersed by any method on a transparent support.

Since the particle size of the color developer has a great influence on the surface roughness of the protective layer and, in particular, the dot reproducibility during printing, the particle size is preferably 0.5 μm or less. The film thickness of the recording layer depends on the composition of the recording layer and the use of the thermal recording medium, but is 1 to
It is about 50 μm, preferably about 3 to 20 μm. Further, if necessary, various additives such as a conventionally known surfactant can be added to the recording layer coating liquid for the purpose of improving coatability or recording characteristics.

In the present invention, a layer containing a pigment, a binder, a heat-fusible substance or the like as an intermediate layer is optionally provided between the support and the thermosensitive coloring layer to improve smoothness. Can be provided.

In the present invention, a protective layer is provided on the thermosensitive coloring layer in order to improve chemical resistance, water resistance, abrasion resistance, light resistance and head matching with a thermal head.

The protective layer of the present invention includes a coating formed mainly of a water-soluble resin or a hydrophobic resin, a coating formed mainly of an ultraviolet curable resin or an electron beam curable resin, and the like. By forming such a protective layer, an organic solvent,
A recording medium having no practical problem can be obtained even by contact with a plasticizer, oil, sweat, water, or the like. Further, by containing an organic or inorganic filler and a lubricant, it is possible to obtain a heat-sensitive recording medium excellent in reliability and head matching property without causing a problem such as sticking caused by contact with a thermal head or the like.

Next, the protective layer of the present invention will be described in detail.
As the binder resin used in the protective layer of the present invention, a binder resin having a refractive index of 1.45 to 1.60 at room temperature is used. Examples of such a resin include a water-soluble resin, an aqueous emulsion, a hydrophobic resin, an ultraviolet curable resin, an electron beam curable resin, and the like. Specific examples of the water-soluble resin include polyvinyl alcohol, modified polyvinyl alcohol, cellulose derivatives (methyl cellulose,
Methoxy cellulose, hydroxyethyl cellulose, etc.), casein, gelatin, polyvinylpyrrolidone, styrene-maleic anhydride copolymer, diisobutylene-maleic anhydride copolymer, polyacrylamide, modified polyacrylamide, methyl vinyl ether-maleic anhydride copolymer Examples thereof include polymer, carboxy-modified polyethylene, polyvinyl alcohol / acrylamide block copolymer, melamine-formaldehyde resin, urea-formaldehyde resin. 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 / acetic acid. Examples thereof include vinyl copolymers, polybutyl methacrylate, ethylene / vinyl acetate copolymers and the like. These may be used alone or as a mixture, and if necessary, a curing agent may be added to cure the resin.

Next, the most preferred ultraviolet curable resin and electron beam curable resin as the protective layer of the present invention will be described in detail. The UV-curable resin used for forming the protective layer is not limited in kind as long as it is a monomer or oligomer (or prepolymer) which undergoes a polymerization reaction upon irradiation with UV rays and becomes a resin by curing, and various known resins are available. All can be used. Examples of such monomers or oligomers include (poly) ester acrylate, (poly) urethane acrylate, epoxy acrylate, polybutadiene acrylate, silicone acrylate, and melamine acrylate. Examples of the (poly) ester acrylate include polyhydric alcohols such as 1,6-hexanediol, propylene glycol (as propylene oxide), and diethylene glycol, and polybasic acids such as adipic acid, phthalic anhydride, and trimellitic acid, and acrylic acid. The thing which was made to react is mentioned.

When the UV curable resin is used, a solvent may be used. Examples of the solvent in this case include tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, chloroform, carbon tetrachloride, ethanol, isopropyl alcohol, acetic acid. Organic solvents such as ethyl, butyl acetate, toluene and benzene can be mentioned. Further, in place of these solvents, a photopolymerizable monomer can be used as a reactive diluent for easy handling.

Examples of the photopolymerizable monomer include 2-ethylhexyl acrylate, cyclohexyl acrylate, butoxyethyl acrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, trimethylolpropane triacrylate, pentaeryi. Examples include trit triacrylate.

Next, the electron beam curable resin will be described. The electron beam curable resin is also not particularly limited in type, but a particularly preferable electron beam curable resin is an electron beam curable resin having a branched molecular structure of 5 or more functional groups having a polyester skeleton (hereinafter referred to as “electron beam curable resin”). Acrylic-modified polyurethane resin ") and a silicone-modified electron beam-curable resin are the main components.

The electron beam curable acrylic modified polyurethane resin can be produced, for example, as follows. That is, a reaction product of 1,4-butanediol and adipic acid, or a reaction product of propylene glycol and adipic acid (the above is equivalent to the polyester skeleton) is a mixture of polyesterdiol and polyethertriol. , Diisocyanate and a compound having an acrylic double bond can be added and reacted. Instead of the mixture of polyester diol and polyether triol, for example, a mixture of polyether diol and polyether triol, a mixture of polyester diol and polyester triol, or a mixture of polyether diol and polyester triol is used. Here, as the diisocyanate,
2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,6-hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, methylene bis (4-phenyl isocyanate), etc., also have an acrylic double bond. 2-hydroxyethyl (meth) acrylate as a compound,
2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, etc. can be illustrated. The polyester diol is, for example, ADEKA NEW ACE Y-30 (manufactured by Asahi Denka Kogyo KK), and the polyether triol is, for example, Sannix TP-40.
0, Sannix GP-3000 (above, Sanyo Chemical Co., Ltd. make) etc. are available.

The molecular weight of the polyester portion of the electron beam-curable acrylic modified polyurethane resin is 200 in order to give the heat-resistant slip layer the flexibility and toughness required.
The range of 0 to 4000 is preferable. Further, the molecular weight of the entire electron beam-curable acrylic modified polyurethane resin is preferably in the range of 20,000 to 50,000 for the same reason as above. In addition, in this resin, effects such as acceleration of curing and improvement of hardness can be brought about by having 5 or more functional groups, preferably 7 to 13 functional groups.

On the other hand, the silicone-modified electron beam curable resin is represented by the following formula.

[0058]

[Chemical 15] (However, in the above formulas, R _{- (CH 2) -n (n} = 0~
3), TDI is 2,4-tolylene diisocyanate, H
EM represents 2-hydroxyethyl acrylate, x =
50-100 and y = 3-6. ) Since this silicone-modified electron beam curable resin has excellent coatability, a uniform and thin coat can be formed well,
Further, since it has a silicone functional group, it has an excellent sliding effect.

When the electron beam curable acrylic modified polyurethane resin and the electron beam curable silicone modified resin are used in combination, the ratio is 100 parts by weight of the electron beam curable acrylic modified polyurethane resin to the electron beam curable silicone. Up to 30 parts by weight of modified resin, preferably 5 to 2
It is desirable to add in the range of 0 parts by weight.

In the protective layer of the present invention, in order to accelerate the curing and improve the heat resistance effect during the formation process,
It is desirable to use a polyfunctional electron beam curable monomer together.
This monomer acts as a cross-linking accelerator and is advantageous in forming a complicated and dense cross-linked structure. Specific examples of such a monomer include trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, pentaerythritol triacrylate, dipentaerythritol hexatriacrylate and the like. Then, it is preferable to add the monomer in an amount of up to 50 parts by weight, preferably 20 to 50 parts by weight, based on 100 parts by weight of the electron beam curable acrylic modified polyurethane resin. If it is more than 50 parts by weight, the lubricating effect is weakened and the sliding effect is reduced.

The protective layer according to the present invention is a phosphazene-based resin having a repeating unit having a phosphazene skeleton represented by the following formula, and is extremely excellent in heat resistance.

[0062]

[Chemical 16] Specific examples include those represented by the following formulas, but the present invention is not limited thereto.

[0063]

[Chemical 17] (Where a and b are a> 0, b ≧ 0, and a + b =
2 is a real number, A is a polymerization-curable group such as a methacryloyloxyethyl group, and B is

[0064]

[Chemical 18] Wherein R _{1 to} R ₅ each represent a hydrogen atom, a chlorine atom, a bromine atom or a halogenated alkyl group having 1 to 4 carbon atoms, and M represents an oxygen atom, a sulfur atom or an imino group. In the case where the phosphazene-based resin represented by the above formula has a polymerization-curable group, it is cured by ultraviolet rays, electron beams, heating, etc. to further improve mechanical strength, hardness and heat resistance.

Further, the improvement of the head matching property of the heat-sensitive recording medium of the present invention is achieved by incorporating an organic or inorganic filler and a slip additive into the protective layer to the extent that transparency is not deteriorated. Examples of the organic filler used in the present invention include polyolefin particles, polystyrene particles, urea-formaldehyde resin particles, or plastic micro hollow sphere particles.As the inorganic filler, aluminum hydroxide, heavy and light calcium carbonate, Zinc oxide, titanium oxide, barium sulfur, silica gel, colloidal silica (10 to 50 μm), alumina sol (10 to 10 μm)
200 μm), activated clay, talc, clay titanium white, kaolinite, calcined kaolinite, diatomaceous earth, synthetic kaolinite, zirconium compounds, glass micro hollow spheres, and the like, and particularly the shape of the filler is spherical,
A material having lubricity such as Si resin or fluororesin is preferable. Examples of the lubricity additive include silicone oil, surfactants, lubricants such as organic salts and waxes, and lubricant fillers. Examples of the silicone oil include dimethylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, alkyl-modified polysiloxane, amino-modified polysiloxane, carboxyl-modified polysiloxane, alcohol-modified polysiloxane and the like.

Examples of the surfactant include commercially available carboxylates, higher alcohol sulfate ester salts, sulfonates, higher alcohol phosphate esters and salts thereof. Specific examples of these compounds include sodium laurate, sodium stearate,
Sodium oleate, sodium lauryl alcohol sulfate, sodium myristyl alcohol sulfate, sodium cetyl alcohol sulfate, sodium stearyl alcohol sulfate, sodium oleyl alcohol sulfate, sodium sulfate ester of ethylene oxide adduct of higher alcohol,
Sodium octyl sulfonate, sodium decyl sulfonate, sodium dodecyl sulfonate, sodium octyl benzene sulfonate, sodium dodecyl benzene sulfonate, potassium dodecyl benzene sulfonate,
Sodium nonylnaphthalenesulfonate, sodium dodecylnaphthalenesulfonate, potassium dodecylnaphthalenesulfonate, sodium N-oleoyl-N-methyltaurine, tetraethoxylauryl alcohol ester, sodium monostearyl ester phosphate, distearyl phosphate sodium salt, etc. However, the present invention is not limited to these.

Examples of the organic salts include metal soaps such as zinc stearate, aluminum stearate, calcium stearate, magnesium stearate, hexyl ammonium chloride, sodium sulfosalicylate, sodium succinate, potassium succinate, and benzoic acid. Examples thereof include salts such as potassium and potassium adipate.

As the waxes, natural waxes such as candelilla wax, carnauba wax, rice wax, beeswax, lanolin wax, montan wax, paraffin wax, microcrystalline wax, synthetic waxes such as polyethylene wax, hardened castor oil or its derivatives, Examples thereof include fatty acid amides. The amount of lubricant in the protective layer is 0.001 to 15.
0 wt% is suitable. If it is more than this range, the mechanical strength of the protective layer is poor, and if it is less than this range, the effect of the lubricant is lost.

There is no particular limitation on the coating method and the coating amount of the protective layer, but the coating amount of the coating layer on the recording medium is 0.1-0.1 in consideration of the performance and economical efficiency of the protective layer. 20
μm range, more preferably 0.5 to 10 μm
Within this range, the performance as a protective layer is sufficiently exhibited and the performance of the recording medium is not deteriorated.

The formation of a recorded image on the transparent thermosensitive recording medium of the present invention varies depending on the purpose of use, but is not particularly limited to thermal pen, thermal head, laser heating, thermal etching using light. However, in practical use, image formation by a thermal head and image formation by thermal etching using light (white light including visible light and infrared light) are useful.

[0071]

EXAMPLES The present invention will be specifically described below with reference to examples. In the following, all parts and% are based on weight.

Example 1 The following composition was pulverized and dispersed by a ball mill to a particle size of 0.3 μm to prepare a color developer dispersion. [Liquid A] Octadecylphosphonic acid 6 parts 10% Polyvinyl butyral resin solution 10 parts (solvent: toluene / methyl ethyl ketone: 5/5) (Denka Butyral # 3000-2 manufactured by Denki Kagaku Kogyo Co., Ltd.) Toluene 15 parts Methyl ethyl ketone 15 parts

Next, [B liquid] prepared by the following composition was sufficiently stirred to prepare a recording layer coating liquid. [Liquid B] Developer dispersion [Liquid A] 23.3 parts 2-anilino-3-methyl-6-diethylaminofluorane 1 part (Hodogaya Chemical Co., Ltd., TH109) Polyester urethane (30% Lacquer) 5 parts (Toyobo Co., Ltd., UR3200) Toluene 5.4 parts Methyl ethyl ketone 5.4 parts

The coating solution prepared as described above is added to 75 μm
m transparent polyester film (Emblet S-75 manufactured by Unitika Ltd., no surface treatment) was applied using a wire bar, applied to a film thickness of about 10 μm, and dried to form a heat-sensitive recording layer. Furthermore, a coating solution for forming a protective layer comprising the following composition was applied onto the heat-sensitive recording layer using a wire bar, heated and dried, and then cured with an 80 w / cm ultraviolet lamp to provide a protective layer having a thickness of about 3 μm. A transparent thermosensitive recording medium was prepared, and the following adhesiveness test method, bending test method,
Adhesion, flexibility, transparency density, and transparency were evaluated by the printing test method and the transparency test method. The results are shown in Table 2.

[0075] [Coating liquid for forming protective layer]   100 parts of urethane acrylate UV curable resin     75% butyl acetate solution     (Dainippon Ink and Chemicals, Unidick C7-157)   52% xylene solution of silicone resin 4 parts     (Byk-344, manufactured by Big Chemie Japan)   50 parts of ethyl acetate

Example 2 Polyester urethane (3) of [B liquid] used in Example 1
Example 1 except that the 0% lacquer) was changed from Toyobo Co., Ltd., UR3200 to Toyobo Co., Ltd., UR8300.
The adhesiveness, flexibility, transparency density and transparency were evaluated in the same manner as in. The results are shown in Table 2.

Example 3 Except that [B liquid] used in Example 1 was changed to the following composition,
The adhesiveness, flexibility, transparent density and transparency were evaluated in the same manner as in Example 1. The results are shown in Table 2. [Liquid B] Developer dispersion [Liquid A] 23.3 parts 2-anilino-3-methyl-6-diethylaminofluorane 1 part (Hodogaya Chemical Co., Ltd., TH109) Polyester urethane (30% Lacquer 1.2 parts (Toyobo Co., Ltd., UR3200) 10% polyvinyl acetal resin solution 14 parts (solvent: toluene / methyl ethyl ketone: 5/5) (Sekisui Chemical Co., Ltd., KS-1) Toluene 1 part Methyl ethyl ketone 1 part

Example 4 The 75 μm transparent polyester film (Unitika Embrette S-75, without surface treatment) used in Example 3 was used as a 75 μm transparent polyester film (Unitika Embrette S-75, double-sided). The adhesiveness, flexibility, transparent density, and transparency were evaluated in the same manner as in Example 3 except that the corona treatment was used instead. The results are shown in Table 2.

Example 5 Except that [B liquid] used in Example 1 was changed to the following composition,
The adhesiveness, flexibility, transparent density and transparency were evaluated in the same manner as in Example 1. The results are shown in Table 2. [Liquid B] Developer dispersion [Liquid A] 23.3 parts 2-anilino-3-methyl-6-diethylaminofluorane 1 part (Hodogaya Chemical Co., Ltd., TH109) Polyester urethane (30% Lacquer 1 part (Toyobo Co., Ltd., UR3200) 10% polyvinyl acetal resin solution 14 parts (solvent: toluene / methyl ethyl ketone: 5/5) (Sekisui Chemical Co., Ltd., KS-1) Toluene 1 part methyl ethyl ketone 1 Department

Example 6 The transparent polyester film of 75 μm (Enblet S-75 manufactured by Unitika Ltd., without surface treatment) used in Example 5 was used as the transparent polyester film of 75 μm (Emblet S-75 manufactured by Unitika Ltd., double-sided). The adhesiveness, flexibility, transparency density, and transparency were evaluated in the same manner as in Example 5 except that the corona treatment was used instead. The results are shown in Table 2.

COMPARATIVE EXAMPLE 1 Except that [B liquid] used in Example 1 was replaced with the following composition,
The adhesiveness, flexibility, transparent density and transparency were evaluated in the same manner as in Example 1. The results are shown in Table 2. [B liquid] Developer dispersion liquid [A liquid] 23.3 parts 2-anilino-3-methyl-6-diethylaminofluorane 1 part (TH109 manufactured by Hodogaya Chemical Co., Ltd.) 10% polyvinyl acetal resin Dissolving solution 15 parts (solvent: toluene / methyl ethyl ketone: 5/5) (KS-1 manufactured by Sekisui Chemical Co., Ltd.) Toluene 0.35 part Methyl ethyl ketone 0.35 part

Comparative Example 2 The transparent polyester film of 75 μm used in Comparative Example 1 (Emblet S-75 manufactured by Unitika Ltd., without surface treatment) was used as a transparent polyester film having a thickness of 75 μm (Emblet S-75 manufactured by Unitika Ltd., double-sided). The adhesiveness, flexibility, transparent density and transparency were evaluated in the same manner as in Comparative Example 1 except that the corona treatment was used instead. The results are shown in Table 2.

Adhesion Test Method A transparent heat-sensitive recording medium of 150 mm × 70 mm was used as a test piece, and it was firmly fixed on a test bench so as not to interfere with the test. Thereafter, the operation is JIS test method 5400-1990.
The test evaluation shown in the following Table 1 was performed based on the cross-cut tape method.

[0084]

[Table 1]

Flexibility test method A transparent thermosensitive recording medium of 100 mm × 100 mm was held at both ends and was bent at 360 ° so that the recording layer was on the outside. ○: No cloudiness of the recording medium △: Some clouding of the recording medium ×: Cloudy of the recording medium

Transmission density test method Thermal head (printing energy: 10.7 mJ / mm
² ) Print and print the transmission density of the printed area and the background area with X-Rit.
It was measured with a transmission densitometer of e309TR (manufactured by XRITE COMPANY).

Transparency test method Direct reading haze computer HG by JISK7105
The haze value was measured with M-2DP (manufactured by Suga Test Instruments Co., Ltd.).

[0088]

[Table 2]

[0089]

As is clear from the detailed and specific description above, the heat-sensitive recording medium of the present invention comprises at least a leuco dye on a transparent support, a developer and a binder capable of heating and coloring the leuco dye. In a heat-sensitive recording medium forming a recording layer made of a binder resin as described above, by containing polyester urethane as the binder resin to improve the adhesiveness between the transparent support and the recording layer, the heat-sensitive recording medium can be cut with a cutter or the like. Even when cut, it does not peel off from the cut end, and exhibits an extremely excellent effect that it is excellent in flexibility when the thermosensitive recording medium is bent.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-186549 (JP, A) JP-A-7-223370 (JP, A) JP-A-8-225781 (JP, A) JP-A-2- 172788 (JP, A) JP 8-34163 (JP, A) JP 7-253632 (JP, A) JP 8-11435 (JP, A) JP 9-254548 (JP, A) JP-A-1-87293 (JP, A) JP-A-8-156420 (JP, A) JP-A-7-309066 (JP, A) JP-A-7-179040 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B41M 5/26-5/40

Claims (3)

(57) [Claims] To 1. A transparent support on which a polyester film, a leuco dye, comprising a binder resin as a color developer and a binder allowed to heat coloring the leuco dye serial
The recording layer is directly formed, and the protective layer is further formed on the recording layer.
A transparent heat-sensitive recording medium comprising
The binder resin to be used is polyester urethane,
Polyester urethane has two or more carboxyl groups
Obtained by the condensation reaction between the polybasic acid and the dihydric alcohol
Of saturated polyester with organic diisocyanate
Urethane bond in the molecular chain obtained by reacting with a long medicine
A transparent heat-sensitive recording medium, which is an elastomer having 2. The transparent thermosensitive recording medium according to claim 1, wherein the content of the polyester urethane in the binder resin is 15% or more. To 3. A process according to claim 1 or 2, characterized in that the surface of the polyester film is corona discharge treatment
The transparent thermosensitive recording medium described .