JPH09234957A - Heat-sensitive recording body and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-sensitive recording body excellent in light resistance, plasticizer resistance, oil resistance, hard matching properties and gloss and its manufacturing method. SOLUTION: This heat-sensitive recording body made of a heatsensitive recording layer, an intermediate layer and an overcoat layer containing resin hardened by the irradiation of electron beam or an overcoat layer mainly made of pigment and aqueous resin formed further on the layer containing resin hardened by the irradiation of electron beam especially under the condition that the resin obtained by hardening under the coexistence of benzotriazole-based ultraviolet absorber having reactive double bond andelectron beam curing resin is employed as the resin hardened by the irradiation of electron beam. Further, this heat-sensitive recording body is manufactured by providing the above- mentioned overcoat layer mainly made of the pigment and the aqueous resin on a plastic film or metal drum as a releasing medium so as to be bonded with a layer containing the resin hardened separately by the irradiation of electron beam and, after that, by irradiating electron beam, the overcoat layer is transferred to the side of the layer containing the resin hardened by the irradiation of electron beam for finishing.

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,
In particular, the present invention relates to a heat-sensitive recording material excellent in light resistance, plasticizer resistance, oil resistance, head matching property and gloss, and a method for producing the same.

[0002]

2. Description of the Related Art Heretofore, a thermosensitive recording medium has been well known in which a color image is obtained by contacting both color-forming substances with heat by utilizing a color reaction between a colorless or light-colored leuco dye and a color developing agent. ing. Since such a thermal recording material is relatively inexpensive, and the recording device is compact and its maintenance is relatively easy, it is not only used as a recording medium for facsimiles and various computers, but also in a wide range of fields such as thermal labels. It is used. However, there are drawbacks in fingerprint resistance, solvent resistance, and the like, for example, when human skin oils or solvents come into contact with the recording layer, the recording density is reduced, or unnecessary coloration called background fog occurs.

On the other hand, in recent years, the number of applications requiring a heat-sensitive recording material excellent in light resistance has been increasing. There is a method of using an ultraviolet absorber as a method for improving the light resistance, but when it is contained in the heat-sensitive recording layer, a sufficient effect cannot be obtained, or unnecessary background fog and the storage stability of the print are deteriorated. There is a drawback to Further, when it is contained in the overcoat layer, there are drawbacks such as adhesion of dust to the printer head and deterioration of surface barrier properties such as plasticizer resistance and oil resistance. It should be noted that in the case where the resin hardened by electron beam irradiation is contained in the overcoat layer, the dust adhesion to the printer head, the plasticizer resistance, the oil resistance, etc. do not always reach a satisfactory level under the present circumstances. is there.

[0004]

DISCLOSURE OF THE INVENTION The inventor of the present invention has earnestly conducted research on a solution to the problem of the conventional thermal recording medium as described above. As a result, the present invention provides a thermosensitive recording layer comprising a support, a thermosensitive recording layer, an intermediate layer, and an overcoat layer containing a resin cured by electron beam irradiation, or a resin cured by the electron beam irradiation. A layer containing a second intermediate layer, which is a thermosensitive recording medium further laminated with an overcoat layer, as a resin cured by electron beam irradiation, a specific ultraviolet absorber and electron beam curing By using a co-curing resinous resin, it is possible to provide a heat-sensitive recording material which is particularly excellent in light resistance, plasticizer resistance and oil resistance, and to provide a method for producing the same.

[0005]

SUMMARY OF THE INVENTION The present invention provides a method for manufacturing a semiconductor device comprising the steps of:
A colorless or light-colored basic dye, a heat-sensitive recording layer containing a colorant and an adhesive as a main component, an intermediate layer, and a heat-sensitive recording body formed by laminating an overcoat layer containing a resin cured by electron beam irradiation, Alternatively, a second recording medium containing a colorless or light-colored basic dye, a heat-sensitive recording layer containing a colorant and an adhesive as a main component, a first intermediate layer, and a resin cured by electron beam irradiation on a support. In a thermosensitive recording medium in which an intermediate layer and an overcoat layer containing a pigment and an aqueous resin as main components are laminated, a benzotriazole-based ultraviolet absorber having a reactive double bond as a resin cured by the electron beam irradiation. A thermosensitive recording medium characterized by using a resin obtained by co-curing an electron beam curable resin and an electron beam curable resin.

Further, according to the present invention, a heat-sensitive recording layer containing a colorless or pale basic dye, a coloring agent and an adhesive as a main component, a first intermediate layer, and an electron beam irradiation are cured on a support. A layer containing a resin as a second intermediate layer, and a further overcoat layer containing a pigment and an aqueous resin as a main component is further laminated thereon,
A second intermediate layer, in which a benzotriazole-based UV absorber having a reactive double bond and an electron beam curable resin are made to coexist on the first intermediate layer, is provided on a plastic film which is separately used as a release medium or An overcoat layer containing a pigment and a water-based resin as a main component is provided on a metal drum surface having a mirror surface smoothness, and then the second intermediate layer surface and the overcoat layer surface are bonded to each other, and an electron is applied from the film surface side or the support surface side. A method for producing a thermosensitive recording medium, characterized in that the overcoat layer is peeled off from the release medium and finished after being cured by irradiation with rays.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The inventor of the present invention has the drawbacks of the conventional thermal recording materials as described above, namely, light resistance, plasticizer resistance,
Further, in a heat-sensitive recording material having a difficulty in oil resistance, earnest studies were conducted to improve it. As a result, the present invention provides a support containing a colorless or light-colored basic dye, a heat-sensitive recording layer containing a colorant and an adhesive as main components, an intermediate layer, and a resin cured by electron beam irradiation. On a thermosensitive recording medium formed by laminating a coat layer, or on a support,
A colorless or light-colored basic dye, a thermosensitive recording layer containing a coloring agent and an adhesive as main components, a first intermediate layer, a second intermediate layer containing a resin cured by electron beam irradiation, and a pigment. A heat-sensitive recording material in which an overcoat layer containing a water-based resin as a main component is laminated, and a method for producing the same, and in particular, a benzotriazole-based ultraviolet absorber having a reactive double bond as a resin cured by electron beam irradiation. By using a resin co-cured with an electron beam curable resin, excellent light resistance, solvent resistance, which the present invention desires,
It was the first discovery that a heat-sensitive recording material having oil resistance was obtained.

The details of the present invention will be described below. In the present invention, various colorless or light-colored basic dyes contained in the heat-sensitive recording layer are known, and the following are exemplified. 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3,
3-bis (p-dimethylaminophenyl) phthalide, 3
Triallylmethane dyes such as-(p-dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl) phthalide, 4,4'-bis-dimethylaminobenzhydrylbenzyl ether, N-halophenyl -Diphenylmethane dyes such as leuco auramine and N-2,4,5-trichlorophenyl leuco auramine, thiazine dyes such as benzoyl leuco methylene blue and p-nitrobenzoyl leuco methylene blue, 3-methyl-spiro-dinaphthopyran, 3- Ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho-
Spiro dyes such as (6′-methoxybenzo) -spiropyran and 3-propyl-spiro-dibenzopyran, lactam dyes such as rhodamine-B anilinolactam, rhodamine (p-nitroanilino) lactam and rhodamine (o-chloroanilino) lactam , 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-N-isoamylamino) -7-
Chloroanilinofluorane, 3-dibutylamino-7-
Chloroanilinofluorane, 3-dibutylamino-6-
Fluoran dyes such as methyl-7-anilinofluorane.

Various kinds of color formers are known as a color former which develops a color by contacting with a basic dye, and the following are exemplified. 2,2-bis (p-hydroxyphenyl) propane, 1,1-bis (p-hydroxyphenyl) propane, 2,2-bis (p-hydroxyphenyl) pentane, 1,1-bis (p-hydroxyphenyl) Pentane, dihydroxydiphenyl ether, 4,
4'-cyclohexylidene diphenol, 4,4'-dihydroxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-isopropyloxydiphenyl sulfone, bis (3-allyl-
4-Hydroxyphenyl) sulfone and other phenol derivatives, zinc 3,5-di-tert-butylsalicylate, 4-
Zinc salts of aromatic carboxylic acids such as zinc [2- (p-methoxyphenoxy) ethyloxy] salicylate and zinc 4- [3- (p-tolylsulfonyl) propyloxy] salicylate, and other N- (p-toluenesulfonyl)- N'-
Phenylurea, N- (p-toluenesulfonyl) -N '
-(P-Tolyl) urea, 1- [α-methyl-α- (4 '
-Hydroxyphenyl) ethyl] -4- [α ', α'-
Bis (4 "-hydroxyphenyl) ethyl] benzene,
And 4,4′-bis (Np-toluenesulfonylaminocarbonylamino) diphenylmethane. Of course, the present invention is not limited to these coloring agents.

The use ratio of the basic dye and the color-developing agent in the recording layer is appropriately selected according to the type of the basic colorless dye and the color-developing agent used, and is not particularly limited.
Generally, 1 to 5 parts by weight of the basic dye is added to the coloring agent in an amount of 1 to 5
It is adjusted to 0 parts by weight, more preferably 1 to 10 parts by weight.

In the present invention, a sensitizer can be used in order to improve the recording sensitivity of the heat-sensitive recording material, and examples of the sensitizer include p-benzyl biphenyl, dibenzyl terephthalate and dibenzyl oxalate. , Di-p-chlorobenzyl oxalate, di-p-methylbenzyl oxalate, dibutyl terephthalate, di-o-chlorobenzyl adipate, 1,2-diphenoxyethane, 1,2-
Di (3-methylphenoxy) ethane, 1-phenoxy-
2- (4-methylphenoxy) ethane, 1,2-bis (3,4-dimethylphenyl) ethane, p-xylene glycol bis (p-tolyloxymethyl) ether,
1,4-bis (p-tolyloxy) benzene, 1,2-
Di (3-methylphenoxy) ethane, 3-phenyl-
Examples are 1,1′-biphenyl, diphenyl sulfone, diphenyl carbonate, stearic acid amide, ethylenebisstearic acid amide, methylol behenic acid amide, oleic acid amide, and palmitic acid amide.

Further, if necessary, various auxiliaries can be appropriately added to the coating liquid for the heat-sensitive recording layer. For example, sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, lauryl alcohol sulfate- Dispersants such as sodium salts, alginates, and fatty acid metal salts, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,
1,3-tris (2-methyl-4-hydroxy-5-te
Examples of the storage stability improver include rt-butylphenyl) butane and 2,2′-methylenebis (4,6-di-tert-butylphenyl) phosphate, and other defoaming agents, fluorescent dyes, coloring dyes and the like.

If necessary, calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, silicon dioxide,
Appropriately add inorganic pigments such as aluminum hydroxide, barium sulfate, zinc sulfate, talc, kaolin, clay, calcined clay, colloidal silica, organic pigments such as styrene microballs, nylon powder, polyethylene powder, urea formalin resin filler, etc. You can also

The recording layer coating liquid containing the above-mentioned materials is
Water is used as a dispersion medium, and the above materials are dispersed or prepared together by an agitator such as an attritor and a sand mill, or separately by a crusher, and then finally prepared as a coating liquid. Examples of the adhesive used in such a coating liquid include the following water-dispersible resins and water-soluble resins. Examples of the water-dispersible resin include styrene-butadiene copolymer emulsion, vinyl acetate-vinyl chloride-ethylene copolymer emulsion, methyl methacrylate-butadiene copolymer emulsion and the like. As the water-soluble resin: starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, diisobutylene-maleic anhydride copolymer salt, styrene-maleic anhydride copolymer salt, ethylene- Examples thereof include acrylic acid copolymer salts and styrene-acrylic acid copolymer salts.
The amount of the adhesive used is 20 to 5 of the total solid content of the thermosensitive recording layer.
It is adjusted in the range of 0% by weight, preferably 25-40% by weight.

Coating method of coating liquid for heat-sensitive recording layer
Is not particularly limited, and is conventionally known and commonly used.
It can be formed according to the technique, for example Barco
Coating, air knife coating, rod breaker
Coating, pure blade coating,
Toduel coating, micro gravure coat
The coating liquid is applied by coating and dried.
Is done. The amount of coating liquid applied is also not particularly limited.
It is not something that is usually 2 to 20 g / m 2 by dry weight. ^Two, Good
More preferably 3 to 15 g / m^TwoIt is a range of degrees. In addition,
Treat the surface of the holder with corona discharge, electron beam irradiation, etc.
Therefore, the coating efficiency can be increased.

In the heat-sensitive recording material of the present invention, an intermediate layer is first provided on the heat-sensitive recording layer thus obtained.
In this case, a coating composition containing a pigment and an aqueous resin as main components is usually used as the intermediate layer. The following substances are exemplified as the aqueous resin used for the intermediate layer. Fully saponified or partially saponified polyvinyl alcohol, acetoacetylated polyvinyl alcohol having an acetoacetyl group introduced by reacting polyvinyl alcohol with diketene, polyvinyl alcohol and fumaric acid,
Fumaric anhydride, trimetic anhydride, a reaction product of a polycarboxylic acid such as itaconic anhydride or an esterified product of these reactants, further vinyl acetate and maleic acid, fumaric acid, itaconic acid, crotonic acid, acrylic acid, Carboxy-modified polyvinyl alcohol obtained as a saponification product of a copolymer with an ethylenically unsaturated carboxylic acid such as methacrylic acid, a copolymer of vinyl acetate and an olefin sulfonic acid such as ethylene sulfonic acid, allyl sulfonic acid, or a salt thereof. Sulfonic acid-modified polyvinyl alcohol obtained as a saponified product, vinyl acetate and an olefin-modified polyvinyl obtained by saponifying a copolymer of ethylene, propylene, isobutylene, α-octene, α-dodecene, α-octadodecene and other olefins. Alcohol, vinyl acetate and acrylonitrile , Nitrile-modified polyvinyl alcohol obtained as a saponification product of a copolymer with nitriles such as methacrylonitrile, and amide-modified polyvinyl alcohol obtained by saponifying a copolymer of vinyl acetate with amides such as acrylamide and methacrylamide. , Pyrrolidone-modified polyvinyl alcohol obtained by saponifying a copolymer of vinyl acetate and N-vinylpyrrolidone, cellulose derivatives such as methylcellulose, ethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, casein, acacia gum, oxidized starch, etherified starch, Starch such as dialdehyde starch, esterified starch, styrene-butadiene copolymer emulsion, vinyl acetate-vinyl chloride-ethylene copolymer emulsion,
Methacrylate-butadiene copolymer emulsion, polyurethane emulsion and the like. Among these aqueous resins, various modified polyvinyl alcohols, cellulose derivatives and casein are preferable, and acetoacetylated polyvinyl alcohols and carboxy-modified polyvinyl alcohols are more preferable in terms of heat resistance and barrier properties. The amount of such an aqueous resin used is not particularly limited, but is 1 with respect to the total solid content of the intermediate layer coating composition.
It is adjusted in the range of 0 to 50% by weight, preferably 15 to 40% by weight.

Examples of the pigment used in the intermediate layer include the following substances. Inorganic pigments such as calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, silicon dioxide, aluminum hydroxide, barium sulfate, zinc sulfate, talc, kaolin, clay, calcined clay, colloidal silica, styrene microballs, nylon powder, polyethylene powder , Urea / formalin resin filler, organic pigments such as raw starch granules, and the like. The amount of the pigment used is generally 5 to 50 with respect to 100 parts by weight of the aqueous resin component.
It is adjusted in the range of 0 parts by weight, preferably 80 to 350 parts by weight (based on the solid content).

Further, in the coating composition for the intermediate layer (coating liquid), glyoxal, methylolmelamine, potassium persulfate, ammonium persulfate, sodium persulfate, ferric chloride, magnesium chloride, boric acid are added to improve water resistance. It is desirable to add a curing agent such as ammonium chloride. If necessary, zinc stearate, calcium stearate, stearamide, potassium stearyl phosphate, polyethylene wax, carnauba wax, paraffin wax, ester wax, and other lubricants, sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, lauryl alcohol sulfate. Ester-sodium salt, alginate, surfactant such as fatty acid metal salt,
Various auxiliaries such as defoaming agents, fluorescent dyes and coloring dyes may be added as appropriate.

The coating liquid for forming the intermediate layer is generally prepared as an aqueous coating liquid, and if necessary, a mixer,
After mixing with an attritor, a ball mill, a roll mill or the like, thoroughly mixing and dispersing with a stirrer, it is coated on the heat-sensitive recording layer by various known coating devices. After the application, curing and drying may be performed by irradiating ultraviolet rays or electron beams. The coating amount of the intermediate layer coating liquid after drying is not particularly limited, but if it is less than 0.1 g / m ² , the effect desired by the present invention cannot be sufficiently obtained. , The other 20g /
If it exceeds m ² , the recording sensitivity of the thermosensitive recording medium may be remarkably reduced. Therefore, the dry weight is generally 0.1 to 20 g / m 2.
² , preferably in the range of about 0.5 to 10 g / m ² . Further, if necessary, by providing a coating layer similar to the intermediate layer on the back surface side of the thermosensitive recording medium, the storage stability can be further improved. Furthermore, by providing an undercoat layer on the support, smoothing treatment with a super calender, etc.,
If necessary, various publicly known techniques in the field of heat-sensitive recording material production can be added, such as processing the back surface of the recording material with an adhesive to process it into an adhesive label.

In the present invention, an overcoat layer containing a resin cured by an electron beam on the intermediate layer thus formed, or a layer containing a resin cured by an electron beam is used as the second intermediate layer. A thermosensitive recording medium (final layer structure) provided on the intermediate layer, and further, an overcoat layer containing a pigment and a water-based resin as a main component is further laminated on the intermediate layer. A resin cured by electron beam irradiation in a state where a benzotriazole-based UV absorber having a reactive double bond and an electron beam curable resin coexist is used as the resin cured by a beam.

Thus, in the present invention, as the electron beam curable resin used, the following monomers and oligomers, or a mixture thereof are used. (A) Radical-polymerizable monofunctional monomer; acrylic acid, ethyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, tetrahydrofurfuryl acrylate, phenoxyethyl acrylate, triloxyethyl Acrylate, nonylphenoxyethyl acrylate, tetrahydrofurfuryloxyethyl acrylate, 1,3-dioxolane acrylate, phenoxydiethylene glycol acrylate, benzyl acrylate, butoxyethyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, dicyclopentenyl acrylate, glycidyl acrylate, carbi. Tall acrylate, isobonyl acrylate And the like.

(B) Radical-polymerizable polyfunctional monomer: 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, tripropylene glycol diacrylate, dicyclopentanyl diacrylate, butylene glycol diacrylate. , Pentaerythritol diacrylate, trimethylolpropane triacrylate, propylene oxide modified trimethylolpropane triacrylate, pentaerythritol triacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol hexaacrylate, caprolactone modified dipentaerythritol hexaacrylate,
Tetramethylol methane tetraacrylate and the like.

(C) As radically polymerizable oligomer (prepolymer); polyester (poly) acrylate,
Polyurethane (poly) acrylate, epoxy (poly)
Examples thereof include acrylate, polyol (poly) acrylate, silicone (poly) acrylate and the like. Furthermore, cationically polymerizable monomers or / and oligomers such as 2-chloroethyl vinyl ether, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, triethylene glycol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether can also be used. it can.

When the cationically polymerizable monomer and / or oligomer is blended, a cationic polymerization initiator is required. Such a cationic polymerization initiator is not particularly limited as long as it is a substance that initiates cationic polymerization by an electron beam, and examples thereof include a diazonium salt, an iodonium salt, a sulfonium salt, and a metallocene compound. The addition amount of these cationic polymerization initiators is preferably about 0.1 to 10 parts by weight with respect to 100 parts by weight of the cationically polymerizable monomer or / and oligomer. Incidentally, if it is less than 0.1 part by weight, the polymerization initiation ability tends to be insufficient, and if it exceeds 10 parts by weight, not only the effect is saturated, but also the solubility of the cationic polymerization initiator is deteriorated and the transparency of the coating film is decreased. There may be adverse effects such as inferiority. Further, as a characteristic of the resin after curing, when an electron beam curable resin having a glass transition temperature (Tg) after curing of 150 ° C. or more is used, the effect of preventing the sticking phenomenon to the head during high-speed recording is excellent. Particularly preferred.

In addition to the above-mentioned electron beam-curable prepolymers and monomers, the electron beam-curable resin component may optionally contain, for example, a non-electron beam-curable resin, as long as the effects of the present invention are not impaired. Resin, antifoaming agent, leveling agent, lubricant, surfactant, plasticizer, UV absorber, fluorescent dye, coloring dye,
Additives such as pigments, fluorescent pigments, and coloring pigments can be added as appropriate.

Incidentally, examples of the non-electron beam curable resin include acrylic resin, silicon resin, alkyd resin, fluororesin, butyral resin and the like. In the present invention, a benzotriazole-based UV absorber having a reactive double bond in a layer containing a resin cured by these electron beams is contained in a layer co-cured with an electron beam curable resin, Specifically, the specific ultraviolet absorber is dissolved or kneaded and mixed in an electron beam curable resin and cured by electron beam irradiation. By coexisting in such a manner, it is possible to improve the surface barrier properties such as dust adhesion to the printer head and plasticizer resistance and oil resistance, which are problems with general ultraviolet absorbers that cannot be co-cured with electron beam curable resins. We have found that it can be greatly improved. In this case, the amount of the benzotriazole-based UV absorber having a reactive double bond used is 1 to 50% by weight, preferably 5% by weight based on the total solid content of the layer containing the UV absorber.
It is adjusted in the range of -40% by weight. Further, in this case, the amount of the electron beam curable resin co-cured is similarly adjusted in the range of 10 to 99% by weight based on the total solid content.

Next, examples of the benzotriazole-based UV absorber having a reactive double bond include a benzotriazole-based UV absorber having a (meth) acrylic oil group, an allyl group, and a vinyl group. 2'-hydroxy-5 '-(2 "-methacryloxyethyl) phenyl] benzotriazole, 2- (2'-hydroxy-3'-allyl-5'-methylphenyl) benzotriazole and the like can be mentioned.

The combination of the benzotriazole type ultraviolet absorber having a reactive double bond and the electron beam curable resin is not particularly limited, but from the viewpoint of reactivity, a methacrylic oil group is used as a functional group. Have 2-
[2′-Hydroxy-5 ′-(2 ″ -methacryloxyethyl) phenyl] benzotriazole is particularly preferable as a combination of free radical polymerization reaction with an acrylic resin, and 2 having an allyl group as a functional group.
In the case of-(2'-hydroxy-3'-allyl-5'-methylphenyl) benzotriazole, a cationic polymerization reaction with a vinyl ether resin is particularly preferable as a combination.

The benzotriazole-based UV absorber having a reactive double bond as described above and the electron beam-curable resin component are thoroughly mixed by a suitable mixing stirrer such as a mixer and the like, and then, are placed on the intermediate layer. Although it is applied by various known methods, the viscosity can be adjusted by heating the resin component as necessary. In addition, although the coating amount is not necessarily limited, the desired effect of the present invention cannot be expected if the coating amount is less than 0.1 g / m ² , and the coating amount is more than 20 g / m ^2. Since it is feared that the recording sensitivity of the recording material may be lowered, it is usually adjusted in the range of 0.1 to ²⁰ g / m ² , and more preferably 0.3 to 10 g / m ² .

As the heat-sensitive recording material of the present invention, a coating in which a resin which is hardened by an electron beam is contained on an intermediate layer (first intermediate layer) containing a usual pigment and an aqueous resin as main components. The layer is provided as a second intermediate layer, and an overcoat layer containing a pigment and an aqueous resin as main components is provided on a plastic film used as a release medium separately or on a metal drum surface having a mirror surface. After bonding the second intermediate layer surface and the overcoat layer surface and curing the resin by electron beam irradiation from the plastic film surface side or the support surface side (when the release medium is a metal drum), the resin is overheated from the release medium. By transferring the coat layer to the second intermediate layer, the obtained thermosensitive recording medium exhibits not only the excellent effect desired by the present invention but also the surface thereof particularly strong gloss and excellent image quality. Thermal recording body is obtained. In this case, as the overcoat layer, the same coating composition as the above-mentioned intermediate layer containing a pigment and an aqueous resin as main components is used.

The plastic film used as the release medium is not particularly limited,
For example, a polyethylene terephthalate film, a polypropylene film, or the like is used as appropriate. In addition, a layer containing a resin that is cured by an electron beam in order to improve the adhesion between the layers and the surface of the layer facing the layer may be subjected to corona treatment if necessary.

In the present invention, the amount of electron beam irradiated is 1
50kGy or less is desirable. Incidentally, excessive electron beam irradiation exceeding 150 kGy may cause coloring or discoloration of the thermosensitive recording medium. The lower limit of the electron beam to be irradiated is not particularly limited, but it is 10 kGy to obtain the desired effect.
The above is desirable. As an electron beam irradiation method, for example, a scanning method, a curtain beam method, a broad beam method, or the like can be adopted, and an accelerating voltage for irradiation is 1
About 100 to 300 KV is suitable. As the support, synthetic paper, plastic film, high-quality paper, coated paper, or the like is appropriately used and is not particularly limited. Further, the recording density and the unevenness of the recording density can be further improved by appropriately smoothing the recording medium after providing the overcoat layer with a super calender or the like.

[0033]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Unless otherwise specified, "part" and "%" in the examples mean "part by weight" and "% by weight", respectively.

Example 1 Preparation of liquid A 3-di (n-butyl) amino-6-methyl-7-anilinofluorane 30 parts 5% aqueous solution of methylcellulose 5 parts water 65 parts This composition was sand milled to give an average particle size of It was crushed to 2 μm.

Preparation of Solution B 2,2-bis (p-hydroxyphenyl) propane 50 parts Methylcellulose 5% aqueous solution 5 parts Water 45 parts This composition was ground with a sand mill until the average particle size became 2 μm.

Liquid C Preparation Di-p-methylbenzyl oxalate 40 parts Methylcellulose 5% aqueous solution 5 parts Water 55 parts This composition was ground with a sand mill until the average particle size became 2 μm.

Formation of Recording Layer 50 parts of A solution, 100 parts of B solution, 35 parts of C solution, 30 parts of SB latex (trade name: Polylac 750K / Mitsui Toatsu Co., Ltd.) (as solid content), and 45 parts of water. Parts were mixed to prepare a coating liquid for recording layer.

The coating liquid thus obtained was coated on a synthetic paper (trade name: YUPO FPG / Oji Yuka Synthetic Paper Co., Ltd.) as a support with a gravure roll to give a coating amount of 10 g / m ² after drying.
After the transfer, the coating amount after smoothing is 5 g / m after smoothing with a bar provided behind the gravure roll.
^The coating amount was adjusted so as to be ² to obtain a thermosensitive recording medium.

Formation of Intermediate Layer On the recording layer of the obtained thermosensitive recording medium, a coating liquid having the following composition was applied and dried so that the coating amount after drying was 2 g / m ^2, and the thermosensitive layer having the intermediate layer was formed. A recording material was prepared. 10% aqueous solution of acetoacetylated polyvinyl alcohol (trade name; Z-200 / Nippon Gosei Kagaku) 100 parts Kaolin (trade name; UW-90 / Engelhard) 20 parts Glyoxal 5% aqueous solution 2 parts Water 40 parts

Formation of Overcoat Layer 90 parts of pentaerythritol triacrylate (trade name; PET-3 / manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), 10 parts of calcium carbonate, 2- [2′-hydroxy-5 ′] on the intermediate layer. −
A mixture of 20 parts of (2 ″ -methacryloxyethyl) phenyl] benzotriazole was kneaded with a three-roll mill and applied so that the dry coating amount was 2 g / m ^2, and the electron curtain type electron beam irradiation device (CB: 150 type / E
(Manufactured by SI Co., Ltd.) at an irradiation dose of 40 kGy to cure the resin component to obtain a final thermosensitive recording medium provided with an overcoat layer containing an electron beam curable resin.

Example 2 In Example 1, before irradiating the overcoat layer of Example 1 with an electron beam, a coating liquid (to be an overcoat layer) having the following composition was separately dried on a polyethylene terephthalate film having a thickness of 38 μm. After coating and drying so that the subsequent coating amount becomes 2 g / m ² , the coating surface is bonded to the electron beam curable resin surface, and then the electron curtain type electron beam irradiation device (CB: 150 type / ESI) is used to cure the resin component by treatment with an irradiation dose of 40 kGy, the polyethylene terephthalate film is peeled off, and the layer containing the electron beam curable resin is used as a second intermediate layer to have an overcoat layer. A final thermosensitive recording medium was obtained. Polyurethane emulsion (trade name; UE-1101 / (solid content 35%) manufactured by Toa Kasei Kagaku) 92 parts Kaolin (trade name; UW-90 / manufactured by Engelhard) 65 parts Stearyl phosphate potassium salt (trade name) Woopol 1800 / (solid content 35%, Matsumoto Yushi-Seiyaku Co., Ltd.) 8 parts water 35 parts

Example 3 In Example 1, in forming the overcoat layer,
Alicyclic epoxy resin (trade name; CyracureUV) on the intermediate layer
R-6110 / Union Carbide Co., Ltd.) 28 parts, triethylene glycol divinyl ether 60 parts, cationic photoinitiator (trade name; Cyracure UVI-6990 / Union Carbide Co., Ltd.) 2 parts, calcium carbonate 10 parts, 2-
Example 1 except that 20 parts of (2′-hydroxy-3′-allyl-5′-methylphenyl) benzotriazole was kneaded with a three-roll mill to apply a mixed solution so that the dry coating amount was 2 g / m ^2. A thermosensitive recording medium was obtained in the same manner as described above.

Example 4 In Example 3, a thermosensitive recording medium having an overcoat layer having an electron beam curable resin as a second intermediate layer was prepared in the same manner as in Example 2 before the overcoat layer was irradiated with an electron beam. Obtained.

Comparative Example 1 In Example 1, in forming the overcoat layer,
2- [2'-hydroxy-5 '-(2 "-methacryloxyethyl) phenyl] benzotriazole instead of 2- (2'-hydroxy-5'-methylphenyl)
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that benzotriazole was used.

Comparative Example 2 In Example 3, in forming the overcoat layer,
2- (2′-hydroxy-3′-allyl-5′-methylphenyl) benzotriazole 2- (2′-hydroxy-5′-methylphenyl) used in Comparative Example 1 instead of
A thermosensitive recording medium was obtained in the same manner as in Example 3 except that benzotriazole was used.

Comparative Example 3 In Example 1, in forming the overcoat layer,
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 2- [2'-hydroxy-5 '-(2 "-methacryloxyethyl) phenyl] benzotriazole was not used.
The following quality tests were carried out on each of the heat sensitive recording materials thus obtained, and the results are shown in Table 1.

(1) Color developability Each thermal recording medium was applied with an applied energy of 0.45 mj / using a thermal recording evaluation machine (TM-PMD type / manufactured by Okura Electric Co., Ltd.).
Dot recording was performed, and the recording density of the obtained recorded image and the density of the unrecorded portion were measured with a Macbeth densitometer (RD-914 type / manufactured by Macbeth).

(2) Glossiness The glossiness of the blank part was measured according to JIS-P-8142.

(3) Light resistance After exposing the thermosensitive recording medium recorded in the above evaluation of color development to direct sunlight for 10 days, the densities of the recorded portion and the unrecorded portion were measured by a Macbeth densitometer (RD-914 type / Macbeth type). (Manufactured by the company).

(4) Resistance to plasticizer A wrap film (trade name; KMA-W / manufactured by Mitsui Toatsu Chemical Co., Ltd.) 3 was placed on a polycarbonate pipe (40 mmφ pipe).
Wrap it around heavily, place the thermosensitive recording material recorded in the above evaluation of color development on it, and wrap the film on top of it.
The color density after being wrapped around heavily and left at 40 ° C. for 24 hours was measured with a Macbeth densitometer (RD-914 type / manufactured by Macbeth Co.) to evaluate the plasticizer resistance.

(5) Oil resistance The edible oil was applied onto the thermosensitive recording medium recorded in the above evaluation of color development, and the color development density after leaving at room temperature for 8 hours was measured by a Macbeth densitometer (RD-914 type / Macbeth company). Manufactured) to evaluate the oil resistance.

(6) Head matching property Each thermal recording material was visually evaluated in the same manner as in the evaluation of color developability as to the degree of dirt (head residue) of the thermal head after recording for 20 m. [Evaluation Criteria] ◯: No head shavings at all ×: Many head shavings and some print defects

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[Table 1]

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As is clear from the results shown in Table 1, the heat-sensitive recording material of the present invention was a heat-sensitive recording material excellent in light resistance, plasticizer resistance, oil resistance and head matching property.

Claims (5)

[Claims] 1. An overcoat containing a thermosensitive recording layer containing a colorless or light basic dye, a colorant and an adhesive as main components, an intermediate layer, and a resin cured by electron beam irradiation on a support. In a heat-sensitive recording material in which layers are laminated, a resin in which a benzotriazole-based UV absorber having a reactive double bond and an electron beam-curable resin are co-cured is used as the resin cured by the electron beam irradiation. A heat-sensitive recording material characterized by the following. 2. A heat-sensitive recording layer containing a colorless or light basic dye, a colorant and an adhesive as main components, a first intermediate layer, and a resin cured by electron beam irradiation on a support. A second intermediate layer, and an overcoat layer containing a pigment and a water-based resin as a main component are laminated, a benzotriazole having a reactive double bond as a resin cured by the electron beam irradiation. A heat-sensitive recording material comprising a resin obtained by co-curing an ultraviolet ray absorbent and an electron beam curable resin. 3. A benzotriazole-based ultraviolet absorber having a reactive double bond is 2- [2'-hydroxy-5'-.
The thermosensitive recording medium according to claim 1 or 2, which is (2 "-methacryloxyethyl) phenyl] benzotriazole. 4. The benzotriazole-based ultraviolet absorber having a reactive double bond is 2- (2′-hydroxy-3′-allyl-5′-methylphenyl) benzotriazole, according to claim 1 or 2. The heat-sensitive recording material described. 5. A heat-sensitive recording layer containing a colorless or light-colored basic dye, a coloring agent and an adhesive as main components, a first intermediate layer, and a resin cured by electron beam irradiation on a support. In the method for producing a heat-sensitive recording material, the second intermediate layer and the overcoat layer containing a pigment and an aqueous resin as main components are laminated, and a benzotriazole having a reactive double bond is provided on the first intermediate layer. A second intermediate layer in which a system ultraviolet absorber and an electron beam curable resin coexist is provided, and a pigment and an aqueous resin are the main components on a plastic film used separately as a release medium or on a metal drum surface having a mirror surface smoothness. And then bonding the second intermediate layer surface and the overcoat layer surface to each other and irradiating them with an electron beam from the film surface side or the support surface side to cure them, and then removing them from the release medium. Method for producing a thermosensitive recording material, characterized in that finish by peeling the bar coating layer.