JPH11334211A - Transparent thermosensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate sticking of a component in a coating layer melted at the time of thermally color developing to a thermal head by incorporating a cellulose ester containing a specific hydroxyl group as a binder resin of a protective layer and spherical particles made of a specific melamine- formaldehyde condensate as a filler. SOLUTION: A resin used for a protective layer is a cellulose ester resin containing a hydroxyl group having a skeleton represented by formula I (wherein R is any one of CH3 , C2 H5 and C3 H7 or a combination of them), and a polyacrylic ester resin, a polyurethane resin or the like is used. As a filler, spherical particles made of a melamine-formaldehyde condensate represented by formula II is used, and accompanied with a cellulose ester resin having a hydroxyl group represented by formula I. As the filler, a phosphate fiber, potassium titanate or the like is used. Thus, head matching properties and a chemical resistance of the thermosensitive recording material which is transparent can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent heat-sensitive recording medium utilizing a color-forming reaction between an electron-donating color-forming compound and an electron-accepting compound, and has excellent chemical resistance.
The present invention also relates to a transparent thermosensitive recording material having excellent head matching properties.

[0002]

2. Description of the Related Art Various recording materials have been proposed which utilize a color-forming reaction between a colorless or pale-colored leuco dye and a color developing agent upon contact with color by heat and pressure. One such heat-sensitive recording material does not require frequent processing such as development and fixing, and can be recorded in a short time with a relatively simple device, has less noise, and has further advantages such as lower cost. Thus, it is useful as various recording materials for electronic computers, facsimile machines, ticket vending machines, label printers, recorders and the like.

As a color-forming dye used in a heat-sensitive recording material, for example, a colorless or light-colored leuco dye having a lactone, lactam or spiropyran ring is used. As a developer, an organic acid, a phenolic substance or the like is conventionally used. ing. The heat-sensitive recording material using this leuco dye and a developer,
It is widely used because of its high image density and high whiteness of the background.

[0004] These heat-sensitive recording materials are generally produced by coating the above-described color-forming dye and color developer on paper. In recent years, a transparent dry film system that can be easily output has been demanded mainly in the medical field due to a waste liquid treatment problem caused by a wet process of a silver halide X-ray film and a flow of digitization of images. In such a flow, a transparent heat-sensitive recording film is also demanded in the heat-sensitive process because of the simplicity of the process.

A thermosensitive recording material using a plastic film as a support has better adhesion between the recording material and the thermal head and better color uniformity as compared to a case where paper is used as a support, but has a higher color uniformity. At the time of coloring, the components in the coating layer dissolve and stick to the thermal head (adhesion of scum), and a phenomenon that causes running failure (hereinafter referred to as sticking) is likely to occur. As a method for improving such a defect, a method using a polyvinyl acetal resin (JP-A-9-104170) has been proposed, but this resin has a defect that it is inferior in chemical resistance, which is a problem for medical use. Also, it cannot be said that head matching is sufficient.

[0006]

SUMMARY OF THE INVENTION In view of the above prior art, it is an object of the present invention to dissolve the components in a coating layer during heating and coloring, which is a problem when a plastic film is used as a support, to adhere to a thermal head. An object of the present invention is to provide a transparent heat-sensitive recording material having no chemical phenomenon (sticking) and excellent in chemical resistance.

[0007]

According to the present invention, a colorless or light-colored leuco dye, a developer for heating the leuco dye to form a color, and a binder resin as a binder are mainly contained on a transparent support. Heat-sensitive recording layer, and further thereon a filler,
In a heat-sensitive recording material provided with a protective layer containing a binder resin as a main component, a cellulose ester containing a hydroxyl group represented by the following general formula (a) is used as the binder resin of the protective layer, and the following general formula is used as a filler: A heat-sensitive recording material is provided, comprising spherical particles composed of a melamine-formaldehyde condensate as represented by (b).

[0008]

Embedded image

[0009]

Embedded image

The details of the thermosensitive recording medium of the present invention will be described below. As described above, white streaks mean that dust on the recording material surface or head scum generated during printing is caught between the thermal recording material and the thermal head during printing travel, and the image is streaked at that portion and in the vicinity thereof. It is a phenomenon that escapes. In the case of sticks, it is a phenomenon in which the components in the coating layer are melted at the time of color development by heat and adhere to the thermal head.

The protective layer of the heat-sensitive recording material generally contains a filler for the purpose of improving heat resistance. However, when applied to a transparent support, transparency is often reduced when a filler is included in the protective layer. In order to maintain transparency by adding a filler, the surface needs to be finely roughened. As this method, it is conceivable to add a filler having a small particle size (average particle size of 0.1 to 0.7 μm) to the protective layer. This filler is not limited to any material as long as it has a small particle size. Depending on the material, it may be agglomerated and large irregularities may be formed, resulting in reduced transparency. In many cases, a difficult surface cannot be formed. In such a case, when a spherical particle composed of the melamine-formaldehyde condensate represented by the above general formula (b) is used in combination with a hydroxyl group-containing cellulose ester resin of the general formula (a) as a filler, it is easily transparent. It has been found that a surface can be formed that is compatible with both properties and head matching.

The content of the particles represented by the above general formula (b) with respect to the entire protective layer is preferably in the range where the filler is exposed on the surface from the viewpoint that the particles form the surface. Preferably, it is contained in an amount of at least% by weight. Considering the improvement in heat resistance and the binding property by the filler, a more preferable range is 50 to 70% by weight.

As the filler which can be used in the present invention, those of the above-mentioned general formula (b) may be used alone. However, in order to prevent blocking and improve matching, transparency and surface properties are not significantly affected. It is also possible to use other fillers.

Examples of fillers include phosphate fibers, potassium titanate, acicular magnesium hydroxide, whiskers, talc, mica, glass flakes, calcium carbonate, plate charcoal, aluminum hydroxide, plate aluminum hydroxide, and silica. , Clay, kaolin, talc, calcined clay, inorganic fillers such as hydrotalcite, crosslinked polystyrene resin particles, urea-formalin copolymer particles, silicone resin particles, crosslinked polymethyl methacrylate resin particles, guanamine-formaldehyde copolymer Examples include organic fillers in the form of particles, but the present invention is not limited thereto.

In the present invention, as the resin used for the protective layer, a cellulose ester resin containing a hydroxyl group having a skeleton represented by the general formula (a) is excellent in solubility in a solvent and compatibility with other resins. It is a preferable material from the viewpoints of particle dispersibility, transparency, and chemical resistance, but in addition to other water-soluble resins, an aqueous emulsion, a hydrophobic resin, ultraviolet rays, an electron beam curing resin, and the like, if necessary. It is also possible. Specific examples of the resin include poly (meth) acrylate resin, polyurethane resin, polyester resin, polyvinyl acetate resin, styrene acrylate resin, polyolefin resin, polystyrene resin, polyvinyl chloride resin, and polyether. Resin, polyamide resin, polycarbonate resin, polyethylene resin,
Examples include a polypropylene resin and a polyacrylamide resin. As the cross-linking agent used with the resin, a conventionally known compound can be used, and an isocyanate compound and an epoxy compound are particularly effective. Specific examples of the isocyanate compound include compounds having two or more isocyanate groups in a molecule such as toluylene diisocyanate, a dimer thereof, diphenylmethane diisocyanate, polymethylene polyphenyl isocyanate, hexamethylene diisocyanate, polyisocyanate, and derivatives thereof. Can be Further, specific examples of the epoxy compound include ethylene glycol diglycidyl ether, butyl glycidyl ether, polyethylene glycol glycidyl ether, epoxy acrylate, and the like.

In order to further improve the head matching property, wax or oil is added to the protective layer, or a resin modified with silicon is used as a binder resin, and the ratio of the resin and the filler is adjusted. The friction coefficient can be adjusted by raising or lowering the friction coefficient. Examples of the waxes that can be used here include stearic acid amide, palmitic acid amide, oleic acid amide, lauric acid amide, ethylene bisstearamide, methylene bisstearamide, methylol stearoamide, paraffin wax, polyethylene, carnauba Wax, paraffin oxide, zinc stearate and the like. As the oil, a general silicone oil or the like can be used.

The support used in the present invention may be a polyester film such as polyethylene terephthalate or polybutylene terephthalate, a cellulose derivative film such as cellulose triacetate, a polyolefin film such as polypropylene or polyethylene, a polystyrene film, or a film obtained by laminating these. Is preferred. Since the transparency of the support also affects the transparency of the entire sheet, it is preferable to use a support having a haze degree of 10% or less in the present invention. As a desirable transparency of the transparent heat-sensitive recording material in the present invention, the haze degree is 40%.
The following is preferred.

The leuco dye used in the present invention is a compound having an electron donating property, and may be used alone or as a mixture of two or more. However, the leuco dye itself is a colorless or light-colored dye precursor, and is not particularly limited. Known ones, for example, triphenylmethanephthalide, triallylmethane, fluoran, phenothiazine, thiofluoran, xanthene, indophthalyl, spiropyran, azaphthalide, chromenopyrazole, methine, rhodamine anilino Leuco compounds such as lactams, rhodamine lactams, quinazolines, diazaxanthenes and bislactones are preferably used. Examples of such compounds include, for example, those shown below.

2-anilino-3-methyl-6-diethylaminofluoran, 2-anilino-3-methyl-6
(Di-n-butylamino) fluoran, 2-anilino-
3-methyl-6- (Nn-propyl-N-methylamino) fluoran, 2-anilino-3-methyl-6- (N
-Isopropyl-N-methylamino) fluoran, 2-
Anilino-3-methyl-6- (N-isobutyl-N-methylamino) fluoran, 2-anilino-3-methyl-
6- (Nn-amyl-N-methylamino) fluoran, 2-anilino-3-methyl-6- (N-sec-butyl-N-ethylamino) fluoran, 2-anilino-
3-methyl-6- (Nn-amyl-N-ethylamino) fluoran, 2-anilino-3-methyl-6- (N
-Iso-amyl-N-ethylamino) fluoran, 2
-Anilino-3-methyl-6- (Nn-propyl-N
-Isopropylamino) fluoran, 2-anilino-3
-Methyl-6- (N-cyclohexyl-N-methylamino) fluoran, 2-anilino-3-methyl-6- (N
-Ethyl-p-toluidino) fluoran, 2-anilino-3-methyl-6- (N-methyl-p-toluidino) fluoran,

2- (m-trichloromethylanilino)-
3-methyl-6-diethylaminofluoran, 2- (m
-Trifluoromethylanilino) -3-methyl-6-diethylaminofluoran, 2- (m-trifluoromethylanilino) -3-methyl-6- (N-cyclohexyl-N
-Methylamino) fluoran, 2- (2,4-dimethylanilino) -3-methyl-6-diethylaminofluoran, 2- (N-ethyl-p-toluidino) -3-methyl-6- (N-ethylanilino ) Fluoran, 2- (N-
Methyl-p-toluidino) -3-methyl-6- (N-propyl-p-toluidino) fluoran, 2-anilino-
6- (Nn-hexyl-N-ethylamino) fluoran,

2- (o-chloroanilino) -6-diethylaminofluoran, 2- (o-bromoanilino) -6
-Diethylaminofluoran, 2- (o-chloroanilino) -6-dibutylaminofluoran, 2- (o-fluoroanilino) -6-dibutylaminofluoran, 2-
(M-trifluoromethylanilino) -6-diethylaminofluoran, 2- (p-acetylanilino) -6
(Nn-amyl-NNn-butylamino) fluoran, 2-benzylamino-6- (N-ethyl-p-toluidino) fluoran, 2-benzylamino-6- (N-
Methyl-2,4-dimethylanilino) fluoran, 2-
Benzylamino-6- (N-ethyl-2,4-dimethylanilino) fluoran, 2-dibenzylamino-6
(N-methyl-p-toluidino) fluoran, 2-dibenzylamino-6- (N-ethyl-p-toluidino) fluoran, 2- (di-p-methylbenzylamino) -6
-(N-ethyl-p-toluidino) fluoran, 2-
(Α-phenylethylamino) -6- (N-ethyl-p
-Toluizino) fluoran,

2-methylamino-6- (N-methylanilino) fluoran, 2-methylamino-6- (N-ethylanilino) fluoran, 2-methylamino-6- (N
-Propylanilino) fluoran, 2-ethylamino-
6- (N-methyl-p-toluidino) fluoran, 2-
Methylamino-6- (N-methyl-2,4-dimethylanilino) fluoran, 2-ethylamino-6- (N-methyl-2,4-dimethylanilino) fluoran, 2-dimethylamino-6- ( (N-methylanilino) fluoran, 2-dimethylamino-6- (N-ethylanilino)
Fluoran, 2-diethylamino-6- (N-methyl-
p-Toluidino) fluoran, 2-diethylamino-6
-(N-ethyl-p-toluidino) fluoran, 2-dipropylamino-6- (N-methylanilino) fluoran, 2-dipropylamino-6- (N-ethylanilino) fluoran,

2-amino-6- (N-methylanilino)
Fluoran, 2-amino-6- (N-ethylanilino)
Fluoran, 2-amino-6- (N-propylanilino) fluoran, 2-amino-6- (N-methyl-p-
Toluidino) fluoran, 2-amino-6- (N-ethyl-p-toluidino) fluoran, 2-amino-6
(N-propyl-p-toluidino) fluoran, 2-amino-6- (N-methyl-p-ethylanilino) fluoran, 2-amino-6- (N-ethyl-p-ethylanilino) fluoran, 2-amino-6 -(N-propyl-
p-ethylanilino) fluoran, 2-amino-6-
(N-methyl-2,4-dimethylanilino) fluoran, 2-amino-6- (N-ethyl-2,4-dimethylanilino) fluoran, 2-amino-6- (N-propyl-2,4 -Dimethylanilino) fluoran, 2-amino-6- (N-methyl-p-chloroanilino) fluoran, 2-amino-6- (N-ethyl-p-chloroanilino) fluoran, 2-amino-6- (N- Propyl-p
-Chloranilino) fluoran,

2,3-dimethyl-6-dimethylaminofluoran, 3-methyl-6- (N-ethyl-p-toluidino) fluoran, 2-chloro-6-diethylaminofluoran, 2-bromo-6-diethylamino Fluoran, 2-chloro-6-dipropylaminofluoran, 3
-Chloro-6-cyclohexylaminofluoran, 3-
Bromo-6-cyclohexylaminofluoran, 2-chloro-6- (N-ethyl-N-isoamylamino) fluoran, 2-chloro-3-methyl-6-diethylaminofluoran, 2-anilino-3-chloro-6 -Diethylaminofluoran, 2- (o-chloroanilino) -3-
Chlor-6-cyclohexylaminofluoran, 2-
(M-Trifluoromethylanilino) -3-chloro-6-
Diethylaminofluoran, 2- (2,3-dichloroanilino) -3-chloro-6-diethylaminofluoran,

1,2-benzo-6-diethylaminofluoran, 1,2-benzo-6- (N-ethyl-N-isoamylamino) fluoran, 1,2-benzo-6-dibutylaminofluoran, 2-benzo-6- (N-ethyl-N-cyclohexylamino) fluoran, 1,2
-Benzo-6- (N-ethyl-toluidino) fluoran 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) fluoran, 2- (p-chloroanilino) -6- (Nn-octylamino) fluoran, 2
-(P-chloroanilino) -6- (Nn-partimylamino) fluoran, 2- (p-chloroanilino) -6
-(Di-n-octylamino) fluoran,

2-benzoylamino-6- (N-ethyl-p-toluidino) fluoran, 2- (o-methoxybenzoylamino) -6- (N-ethyl-p-toluidino) fluoran, 2-dibenzylamino- 4-methyl-
6-diethylaminofluoran, 2-dibenzylamino-4-methoxy-6- (N-methyl-p-toluidino)
Fluoran, 2-dibenzylamino-4-methyl-6
(N-ethyl-p-toluidino) fluoran, 2- (α
-Phenylethylamino) -4-methyl-6-diethylaminofluoran, 2- (p-toluidino) -3- (t
-Butyl) -6- (N-methyl-p-toluidino) fluoran, 2- (o-methoxycarbonylanilino) -6
-Diethylaminofluoran, 2-acetylamino-6
-(N-methyl-p-toluidino) fluoran, 3-diethylamino-6- (m-trifluoromethylanilno) fluoran, 4-methoxy-6- (N-ethyl-p
-Toluidino) fluoran, 2-ethoxyethylamino-3-chloro-6-dibutylaminofluoran, 2-dibenzylamino-4-chloro-6- (N-ethyl-p-
Toluidino) fluoran, 2- (α-phenylethylamino) -4-chloro-6-diethylaminofluoran,
2- (N-benzyl-p-trifluoromethylanilino)
-4-chloro-6-diethylaminofluoran,

2-anilino-3-methyl-6-pyrrolidinofluoran, 2-anilino-3-chloro-6-pyrrolidinofluoran, 2-anilino-3-methyl-6- (N
-Ethyl-N-tetradrofurfurylamino) fluoran, 2-mesitidino-4 ', 5'-benzo-6-diethylaminofluoran, 2- (m-trifluoromethylanilino) -3-methyl-6-pyrroli Dinofluoran, 2-
(Α-naphthylamino) -3,4-benzo-4′-bromo-6- (N-benzyl-N-cyclohexylamino)
Fluoran, 2-piperidino-6-diethylaminofluoran, 2- (Nn-propyl-p-trifluoromethylanilino) -6-morpholinofluoran, 2- (di-Np-chlorophenyl-methyl) Amino) -6-pyrrolidinofluoran, 2- (Nn-propyl-m-trifluoromethylanilino) -6-morpholinofluoran,

1,2-benzo-6- (N-ethyl-N-
n-octylamino) fluoran, 1,2-benzo-6
-Diallylaminofluoran, 1,2-benzo-6-
(N-ethoxyethyl-N-ethylamino) fluoran, benzolecomethylene methylene-, 2- (3,6-bis (diethylamino))-6- (o-chloroanilino) xanthyl benzoate lactam, 2- (3,6 -Bis (diethylamino))-9- (o-chloroanilino) xanthylbenzoic acid 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) fluorenespiro (9,3 ′)-6′-dimethylaminophthalide, 6′-chloro-8′-methoxy-benzoindolino-spiropyran, 6'-bromo-
2'-methoxy-benzoindolino-spiropyran and the like.

Next, the developer used in the present invention is an electron-accepting compound, and various conventionally known electron-accepting developers can be used. Preferred are electron-accepting developers containing a long-chain alkyl group in the molecule described in JP-A-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, a metal salt of a mercaptoacetic acid having an aliphatic group having 10 to 18 carbon atoms, or a metal salt of 5 to 8 carbon atoms And alkyl phosphates of caffeic acid having an alkyl group, and acidic phosphate esters having an aliphatic group having 16 or more carbon atoms. The aliphatic group includes a linear or branched alkyl group and alkenyl group, and may have a substituent such as a halogen, an alkoxy group, and an ester. Hereinafter, specific examples of the developer will be described.

(A) Organic phosphoric acid compounds Those represented by the following general formula (1) are preferably used.

[0033]

Embedded image (In the formula, R ₁ represents a linear alkyl group having 12 to 24 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.

[0035]

Embedded image (In the formula, 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-hydroxydodecylphosphonic acid. Hydroxytetradecylphosphonic acid, α-
Examples include hydroxyhexadecylphosphonic acid, α-hydroxyoctadecylphosphonic acid, α-hydroxyeicosylphosphonic acid, α-hydroxydocosylphosphonic acid, and α-hydroxytetracosylphosphonic acid.

As the organic phosphoric acid compound, an acidic organic phosphoric acid ester represented by the following general formula (3) is also used.

[0037]

Embedded image (Wherein, 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.) The acidic organic phosphoric acid ester represented by the general formula (3) Specifically, dihexadecyl phosphate, dioctadecyl phosphate, dieicosyl phosphate, didicosyl phosphate, monohexadecyl phosphate,
Monooctadecyl phosphate, monoeicosyl phosphate, monodocosyl phosphate, methyl hexadecyl phosphate, methyl octadecyl phosphate, methyl eicosyl phosphate, methyl docosyl phosphate, amyl hexadecyl phosphate, octyl hexadecyl phosphate, lauryl hexadecyl phosphate, etc. Can be

(B) Aliphatic carboxylic acid compounds α-hydroxy fatty acids represented by the following general formula (4) are preferably used.

[0039]

Embedded image (In the formula, 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-hydroxyhexacocanoic acid, α-hydroxyoctacosanoic acid and the like.

The aliphatic carboxylic acid compound is an aliphatic carboxylic acid compound having an aliphatic group having 12 or more carbon atoms and substituted with a halogen element, at least in the α-position or β-position.
Those having a halogen element at the carbon at the 2nd position are also preferably used. Specific examples of such compounds include, for example, the following. 2-bromohexadecanoic acid, 2-bromoheptadecanoic acid, 2-bromooctadecanoic acid, 2-bromoeicosanoic acid, 2-bromodocosanoic acid, 2-bromotetracosanoic acid, 3-bromooctadecanoic acid, 3-bromoeicosanoic acid 2,2-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, 2
-Iodooctadecanoic acid, perfluorooctadecanoic acid and the like.

The aliphatic carboxylic acid compound is an aliphatic carboxylic acid compound having an oxo group in the carbon and having an aliphatic group having 12 or more carbon atoms, wherein at least the carbon at the α-position, the β-position or the γ-position is an oxo group. Are preferably used. Specific examples of such compounds include, for example, the following. 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-oxodokosanoic acid and the like.

As the aliphatic carboxylic acid compound, a dibasic acid represented by the following general formula (5) is also preferably used.

[0043]

Embedded image (Wherein, R ₆ represents an aliphatic group having 12 or more carbon atoms;
Represents an oxygen atom or a sulfur atom, and n represents 1 or 2. As specific examples of the dibasic acid represented by the general formula (5),
For example, the following are mentioned. Dodecyl malate, tetradecyl malate, hexadecyl malate, octadecyl malate, eicosyl malate, docosyl malate, tetracosyl malate, dodecyl thiomalate, tetradecyl thiomalate, hexadecyl thiomalate,
Octadecylthiomalic acid, eicosylthiomalic acid,
Docosylthiomalic acid, tetracosylthiomalic acid, dodecyldithiomalic acid, tetradecyldithiomalic acid,
Eicosyldithiomalic acid, docosyldithiomalic acid,
Tetracosyldithiomalic acid and the like.

As the aliphatic carboxylic acid compound, a dibasic acid represented by the following general formula (6) is also preferably used.

[0045]

Embedded image (Wherein R ₇ , R ₈ and R ₉ represent hydrogen or an aliphatic group,
At least one of them is an aliphatic group having 12 or more carbon atoms. As specific examples of the dibasic acid represented by the general formula (6),
For example, the following are mentioned. Dodecyl butane diacid,
Tridecyl butane diacid, tetradecyl butane diacid, pentadecyl butane diacid, octadecyl butane diacid, eicosyl butane diacid, docosyl butane diacid, 2,3-dihexadecyl butane diacid, 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-dodecyl butane diacid, 2-octyl-3-hexadecyl butane diacid, 2-tetradecyl-3-octadecyl butane diacid, and the like.

As the aliphatic carboxylic acid compound, a dibasic acid represented by the following general formula (7) is also preferably used.

[0047]

Embedded image (Wherein, 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) as,
For example, the following are mentioned. Dodecylmalonic acid, tetradecylmalonic acid, hexadecylmalonic acid, octadecylmalonic acid, eicosylmalonic acid, docosylmalonic acid, tetracosylmalonic acid, didetecylmalonic acid, ditetradecylmalonic acid, dihexadecylmalonic acid, dioctadecylmalon Acid, dieicosylmalonic acid, didocosylmalonic acid, methyloctadecylmalonic acid, methyldocosylmalonic acid, methyltetracosylmalonic acid, ethyloctadecylmalonic acid, ethyleicosylmalonic acid, ethyldocosylmalonic acid, ethyltetracosyl Malonic acid and the like.

As the aliphatic carboxylic acid compound, a dibasic acid represented by the following general formula (8) is also preferably used.

[0049]

Embedded image (Wherein, R ₁₂ represents an aliphatic group having 12 or more carbon atoms;
Represents 0 or 1, m represents 1, 2 or 3,
When n is 0, m is 2 or 3, and when n is 1, m
Represents 1 or 2. As specific examples of the dibasic acid represented by the general formula (8),
For example, the following are 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-hexanedioic acid, 2-docosyl-hexanedioic acid and the like.

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 those shown in Table 1 below.

[0051]

[Table 1]

(C) Phenol compound A compound represented by the following general formula (9) is preferably used.

[0053]

Embedded image (Wherein 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) include the following. 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, hexadecyl gallate, octadecyl gallate, eicosyl gallate, docosyl gallate, tetracosyl gallate, and the like.

As the phenol compound, an alkyl caffeic acid ester represented by the following general formula (10) can also be used.

[0055]

Embedded image (In the formula, 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-pentyl and caffeic acid-n-. Hexyl, caffeic acid-n-octyl and the like.

(C) Metal salt of mercaptoacetic acid A metal salt of alkyl or alkenyl mercaptoacetic acid represented by the general formula (11) can be preferably used.

[0057]

Embedded image (Wherein, R ₁₅ represents an aliphatic group having 10 to 18 carbon atoms,
M represents tin, magnesium, zinc or copper. Specific examples of the metal mercaptoacetate represented by the general formula (11) include the following. Tin decyl mercapto acetate, tin dodecyl mercapto acetate, tin tetradecyl mercapto acetate, tin hexadecyl mercapto acetate, tin octadecyl mercapto acetate, magnesium decyl mercapto acetate, magnesium dodecyl mercapto acetate, magnesium tetradecyl mercapto acetate , Magnesium hexadecylmercaptoacetate, magnesium octadecylmercaptoacetate, zinc decylmercaptoacetate, zinc dodecylmercaptoacetate, zinc tetradecylmercaptoacetate, zinc hexadecylmercaptoacetate, zinc octadecylmercaptoacetate, copper decylmercaptoacetate Salt, copper dodecylmercaptoacetate, copper tetradecylmercaptoacetate, copper hexadecylmercaptoacetate, copper octadecylmercaptoacetate Etc..

In the present invention, the color developer is not limited to the compounds described above, but may be a general 4,4'-isopropylidenebisphenol or 4,4 '
It is possible to use various other electron-accepting compounds such as phenolic developers such as isopropylidenebis (o-methylphenol), salicylic acid, carboxylic acid developers and metal salt developers. it can.

In the heat-sensitive recording medium of the present invention, the developer is used in an amount of 1 to 20 parts, preferably 2 to 10 parts, per part of the color former. The color developer can be applied alone or as a mixture of two or more types, and the color former can also be applied alone or as a mixture of two or more types.

Next, various known resins can be used as the binder resin in the thermosensitive coloring layer used in the present invention.
For example, polyacrylamide, maleic acid copolymer, polyacrylate, polymethacrylate,
Vinyl chloride / vinyl acetate copolymer, styrene copolymer,
Polyester, polyurethane, polyvinyl butyral,
Ethyl cellulose, polyvinyl acetal, polyvinyl acetoacetal, polycarbonate, epoxy resin,
Polyamide and the like. Here, as in the case of the protective layer, it is preferable from the viewpoint of transparency to use a resin having a ratio of the refractive index of the resin to the refractive index of the support between 0.8 and 1.2. In addition, the content of the binder resin in the thermosensitive coloring layer is preferably 15% or more of the total solid content of the thermosensitive coloring layer from the viewpoint of transparency, and more preferably in consideration of the substrate adhesiveness, the coloring property, and the like. Is in the range of 25 to 40%.

The specific examples of the leuco dye, the color developer, and the binder resin which are the main components in the heat-sensitive coloring layer of the heat-sensitive recording material of the present invention have been described above, but the invention is not limited thereto. Also,
If necessary, known fillers, pigments, surfactants, and heat-fusible substances can be added.

Organic resins (toluene, methyl ethyl ketone, alcohols, etc.) among the resins used for the protective layer of the present invention.
When used on a thermosensitive coloring layer, the leuco dye and the developer generally dissolve and come into contact with each other to form a color immediately after coating. In order to prevent this color formation, a leuco dye and / or a developer which are insoluble or slightly soluble in the solvent to be used are selected and used. The leuco dye and / or the developer is coated with the microcapsules so that the dye and the developer hardly come into contact with each other. A resin layer is provided on the thermosensitive coloring layer to make it difficult for the dye and the developer to come into contact with each other. It is desirable to take such a method. Among them, it is preferable to use the organic phosphoric acid compound represented by the general formula (1) as a color developer in terms of avoiding fog by a solvent, color sensitivity, and color density. When this compound is used as a color developing agent, resins having a hydroxyl group among the resins used in the above-mentioned heat-sensitive recording layer are preferable from the viewpoint of color development and storage. Specific examples include polyvinyl butyral and polyvinyl acetoacetal.

In the heat-sensitive recording layer of the present invention, a color former (dye) and a developer are uniformly dispersed or dissolved in water or an organic solvent together with a binder resin or microencapsulated, and this is coated on a support and dried. The coating method is not particularly limited. When a dye or a developer is dispersed or microencapsulated in the recording layer coating solution, the particle size of the dye, the developer or the microcapsules containing these is determined by the surface roughness of the protective layer, the transparency, Since the particle size greatly affects dot reproducibility during printing, the particle size is 1.0
μm or less is preferred. The thickness of the recording layer is about 1 to 50 μm, preferably about 3 to 20 μm, although it depends on the composition of the recording layer and the use of the thermosensitive recording medium. In addition, various additives such as a surfactant can be added to the recording layer coating liquid, if necessary, 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 is provided as an intermediate layer between the support and the thermosensitive coloring layer, if necessary, for example, to improve smoothness. be able to. In addition, a back layer can be provided as required for preventing curling and charging. The coating method of the protective layer is not particularly limited, and the coating can be performed by a conventionally known method. The preferred thickness of the protective layer is 0.1 to 20 μm.
m, more preferably 0.5 to 10 μm. If the thickness of the protective layer is too thin, the storage layer of the recording medium and the function as a protective layer such as head matching are insufficient, and if it is too thick, the thermal sensitivity of the recording medium decreases and the cost is disadvantageous.
The recording method of the transparent thermosensitive recording medium of the present invention is not particularly limited, such as a hot pen, a thermal head, and laser heating, depending on the purpose of use.

[0065]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. In the following, “parts” and “%” are based on weight. As for the particle size, the result measured by a laser diffraction type particle size measuring device (HORIBA LA-700) is described. Example 1 The following composition was pulverized and dispersed in a ball mill to a particle size of 0.3 μm to prepare a recording layer coating solution. [Solution A] 2-anilino-3-methyl-6-diethylaminofluoran 4 parts Octadecylphosphonic acid 12 parts Polyvinyl butyral 2 parts (Denka Butyral # 3000-2 manufactured by Denki Kagaku Kogyo Co., Ltd.) Polyvinyl acetoacetal 6 parts (Sekisui Chemical 57 parts of methyl ethyl ketone (MEK) 57 parts of the coating solution prepared as described above was coated on a 75 μm-thick polyester film (Unitika T-75) [Solution A].
And dried to form a heat-sensitive recording layer having a thickness of 10 μm.

Next, the following composition was dispersed in a ball mill to prepare a filler dispersion liquid [B liquid]. [Liquid B] Melamine-formaldehyde copolymer particles 30 parts (Nippon Shokubai, Eposter S) Cellulose ester resin solution 30 parts (Kodak, CAP-482-0.5, 10% MEK solution) Methyl ethyl ketone 140 parts The particle size of the dispersion at this time was 0.19 μm.

Further, the following composition was dispersed in a ball mill to prepare a filler dispersion liquid [liquid C]. [Solution C] Zinc stearate 30 parts Cellulose ester resin solution 30 parts (manufactured by Kodak, CAP-482-0.5, 10% MEK solution) Methyl ethyl ketone 140 parts The particle size of the dispersion at this time is 0.60 μm Met.

Further, the following composition was sufficiently stirred to prepare a protective layer coating liquid [D liquid]. [D solution] 100 parts of B solution 13 parts of C solution 83 parts of cellulose ester resin solution (CAP-482-0.5, 10% MEK solution of Kodak) Toluylene diisocyanate derivative 10 parts (Nippon Polyurethane Industry, Coronate L) 74 parts of methyl ethyl ketone The protective layer coating solution [D solution] prepared as described above was subjected to ultrasonic treatment for 15 minutes, and then applied onto the previously obtained heat-sensitive recording layer, dried, and dried. A protective layer having a thickness of 2.0 μm;
A thermosensitive recording medium of the present invention was produced.

Example 2 A heat-sensitive recording layer was formed on a polyester film (T-75 manufactured by Unitika) in the same manner as in Example 1. Further, the following composition was sufficiently stirred to prepare a protective layer coating solution [E solution]. [Solution E] Solution B 100 parts Solution C 30 parts Cellulose ester resin solution 130 parts (Kodak CAP-482-0.5, 10% MEK solution) Methyl ethyl ketone 85 parts Protective layer prepared as above The coating liquid [E liquid] was subjected to ultrasonic treatment for 15 minutes, and then coated and dried on the previously obtained heat-sensitive recording layer to provide a protective layer having a thickness of 2.0 μm.
A thermosensitive recording medium of the present invention was produced.

Example 3 A heat-sensitive recording layer was formed on a polyester film (T-75 manufactured by Unitika) in the same manner as in Example 1. Next, the following composition was dispersed by a ball mill to prepare a filler dispersion liquid [F liquid]. [Solution F] Melamine-formaldehyde copolymer particles 30 parts (Nippon Shokubai, Eposter S) Cellulose ester resin solution 30 parts (Kodak, CAB-553-0.4, 10% MEK solution) 140 parts of methyl ethyl ketone The particle size of the dispersion at this time was 0.22 μm.

Next, the following composition was dispersed in a ball mill,
A filler dispersion liquid [G liquid] was prepared. [G solution] Zinc stearate 30 parts Cellulose ester resin solution 30 parts (manufactured by Kodak, CAB-553-0.4, 10% MEK solution) Methyl ethyl ketone 140 parts The particle size of the dispersion at this time is 0.68 μm Met.

Further, the following composition was sufficiently stirred to prepare a protective layer coating solution [H solution]. [H solution] 100 parts of F solution 13 parts of G solution 83 parts of cellulose ester resin solution (CAB-553-0.4, 10% MEK solution of Kodak) Toluylene diisocyanate derivative 10 parts (Nippon Polyurethane Industry, Coronate L) 74 parts of methyl ethyl ketone The protective layer coating solution [solution H] prepared as described above was subjected to ultrasonic treatment for 15 minutes, and then applied onto the previously obtained heat-sensitive recording layer, dried, and dried. A protective layer having a thickness of 2.0 μm;
A thermosensitive recording medium of the present invention was produced.

Comparative Example 1 A 10 μm heat-sensitive recording layer was provided on a polyester film (T-75 manufactured by Unitika) in the same manner as in Example 1. Next, the following composition was dispersed by a ball mill to prepare a filler dispersion liquid [I liquid]. [Solution I] Kaolinite powder 30 parts (Tsuchiya Kaolin, ASP-170) Polyvinyl acetoacetal resin solution 30 parts (Sekisui Chemical, KS-1, 10% MEK solution) Methyl ethyl ketone 140 parts The particle size was 0.6 μm. Further, the following composition was sufficiently stirred to prepare a protective layer coating solution [solution J]. [Solution J] 100 parts Solution I Polyvinyl acetoacetal resin solution 105 parts (Sekisui Chemical, KS-1, 10% MEK solution) Silicon modified polyvinyl butyral resin 24 parts (Dainichi Seika, SP-712, 12. (5% MEK solution) 72 parts of methyl ethyl ketone The protective layer coating solution [solution J] prepared as described above was subjected to ultrasonic treatment for 15 minutes, and then applied onto the previously obtained heat-sensitive recording layer and dried. Then, a protective layer having a thickness of 2.0 μm was provided, and a thermosensitive recording medium of a comparative example was produced.

Comparative Example 2 A 10 μm heat-sensitive recording layer was provided on a polyester film (T-75 manufactured by Unitika) in the same manner as in Example 1. Next, the following composition was dispersed in a ball mill to prepare a filler dispersion liquid [K liquid]. [K liquid] Melamine-formaldehyde copolymer particles 30 parts (Nippon Shokubai, Eposter S) Acrylic resin solution 30 parts (Mitsubishi Rayon, BR73, 10% MEK solution) Methyl ethyl ketone 140 parts Particles of dispersion at this time The diameter was 0.73 μm. Further, the following composition was sufficiently stirred to prepare a protective layer coating solution [L solution]. [L solution] K solution 100 parts Acrylic resin solution 105 parts (Mitsubishi Rayon, BR73, 10% MEK solution) Silicon modified polyvinyl butyral resin 24 parts (Dainichi Seika, SP-712, 12.5% MEK solution) Liquid) 72 parts of methyl ethyl ketone The protective layer coating liquid [Liquid L] prepared as described above was subjected to ultrasonic treatment for 15 minutes, applied onto the previously obtained thermosensitive recording layer, dried, and dried. Providing a 2.0 μm protective layer,
A thermosensitive recording medium of a comparative example was produced.

Comparative Example 3 A 10 μm heat-sensitive recording layer was provided on a polyester film (T-75 manufactured by Unitika) in the same manner as in Example 1. Next, the following composition was dispersed by a ball mill to prepare a filler dispersion liquid [M liquid]. [M liquid] Kaolinite powder 30 parts (Tsuchiya Kaolin, ASP-170) Cellulose ester resin solution 30 parts (Kodak, CAP-482-0.5, 10% MEK solution) Methyl ethyl ketone 140 parts The particle size of the dispersion was 0.53 μm. Further, the following composition was sufficiently stirred to prepare a protective layer coating solution [N solution]. [N solution] M solution 100 parts Cellulose ester resin solution 57 parts (Sekisui Chemical, KS-1, 10% MEK solution) Silicon modified polyvinyl butyral resin 16 parts (Dainichi Seika, SP-712, 12.5 % MEK dissolution solution) 69 parts of methyl ethyl ketone The protective layer coating solution [N solution] prepared as described above was subjected to ultrasonic treatment for 15 minutes, and then applied onto the previously obtained thermosensitive recording layer and dried. A protective layer having a thickness of 2.0 μm;
A thermosensitive recording medium of a comparative example was produced.

Comparative Example 4 The following composition was ground and dispersed in a ball mill to a particle size of 0.7 μm to prepare a dispersion. [Liquid O] 2-anilino-3-methyl-6-diethylaminofluoran 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts [Liquid P] 4-isopropoxy-4'-hydroxydiphenylsulfone 20 parts Polyvinyl alcohol 10% aqueous solution 25 parts Water 50 parts [Solution Q] Silica 20 parts 10% aqueous solution of methylcellulose 20 parts Water 60 parts Adjustment of thermal recording layer [Solution R] [Solution O] 15 parts [Solution P] 45 parts [Solution Q] 45 parts 20% alkaline aqueous solution of isobutylene / maleic anhydride copolymer 5 parts [R solution] was coated on a 75 μm thick polyester film (Unitika T-75) with the heat-sensitive coating solution prepared as described above. After drying, a thermosensitive recording layer having a thickness of 10 μm was formed. The protective layer solution [solution J] of Comparative Example 1 was applied on this heat-sensitive layer and dried to form a protective layer having a thickness of 20 μm, thereby producing a heat-sensitive recording medium of Comparative Example.

The heat-sensitive recording medium produced as described above was evaluated as follows.・ Transparency JIS7105 by direct reading haze meter manufactured by Suga Test Machine
It measured according to. -White streaks Transmission density (X-Rite 309; Visual) with the medium of Example 1 using a video printer UP-930 manufactured by Sony Corporation.
The average number of white streaks was calculated by printing at n = 3 for each example with an energy that makes the (l filter) 2.0. -Sticking: Print with the energy of 1.5 of the medium of Example 1 using the medium of Example 1 with the video printer UP-930 manufactured by Sony Corporation, and evaluate the sticking sound between the thermal recording medium and the thermal head during printing based on the following criteria. did. (Standard) ◎: No sticking sound ○: Almost no sticking sound △: There is sticking sound ×: Loud sticking sound ・ Ethanol resistance After rubbing the recording medium surface five times with a cotton swab impregnated with ethanol Surface condition

[0078]

[Table 2]

[0079]

As is apparent from the above detailed and specific description, the transparent thermosensitive recording material of the present invention has a spherical shape comprising a cellulose ester containing a hydroxyl group as a resin in a protective layer and a melamine-formaldehyde condensate as a filler. By containing particles, it is extremely excellent in head matching and chemical resistance while being transparent.

Claims (3)

[Claims] 1. A heat-sensitive recording layer comprising, as a main component, a colorless or light-colored leuco dye, a developer for causing the leuco dye to develop a color and a binder resin as a binder, on a transparent support.
Further, in a thermosensitive recording material having a protective layer mainly composed of a filler and a binder resin provided thereon, a cellulose ester containing a hydroxyl group represented by the following general formula (a) as a binder resin of the protective layer. A heat-sensitive recording material comprising, as a filler, spherical particles comprising a melamine-formaldehyde condensate represented by the following general formula (b): Embedded image Embedded image 2. The heat-sensitive recording material according to claim 1, wherein an isocyanate compound is used as a crosslinking agent for the protective layer. 3. The developer used in the recording layer is an organic phosphoric acid compound represented by the following general formula (1), and a resin having a hydroxyl group in a molecule is used as the binder resin for the recording layer. Item 3. The heat-sensitive recording material according to Item 1 or 2. Embedded image