JPH0872401A - Double thermosensitive recording medium and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] [Purpose] It is possible to obtain uniform printing with less unevenness and less wrinkles and wrinkles. [Structure] A support A, a thermosensitive color recording layer A, an active energy ray-curable resin layer, a support B which can be peeled from the interface with the active energy ray curable resin layer, and a thermosensitive color recording layer B are provided in this order.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double thermosensitive recording medium in which two thermosensitive recording media are bonded together, and further to a method for efficiently producing the thermosensitive recording media.

[0002]

2. Description of the Related Art Conventionally, a colorless to light-colored basic dye,
A heat-sensitive recording material utilizing a color reaction with an organic or inorganic color developing agent to bring a color developed image by contacting both color developing materials with heat is well known. Since such a heat-sensitive recording material is relatively inexpensive and the recording equipment is compact and its maintenance is relatively easy, it is used in a wide range of fields such as recording media such as facsimiles and various computers, and heat-sensitive labels.

By the way, if there is a product such as a pressure-sensitive copying paper which can make a plurality of copies of a thermal recording medium at the same time, its application is widened, and therefore several methods have been proposed. For example, a method in which a plurality of thermosensitive recording media are pasted together by applying pressure using waxes (Japanese Patent Publication No. 53-48101, Japanese Patent Publication No. 57-54318), a thermosensitive layer containing polyvinyl alcohol is coated on a substrate, There is a method in which, while being in a wet state, another substrate is laminated and dried, and then a heat-sensitive layer is provided on the laminated substrate (Japanese Patent Publication No. 64-500504). However, with this method, it is difficult to pressurize uniformly, so that the bonded surface is likely to be non-uniform, and thus uneven printing is likely to occur. Further, since waxes have weak interlayer strength, the peeling surface is not constant when peeled, and it is difficult to control the peelability, and the gloss of the lower thermosensitive color recording layer surface after peeling the upper thermosensitive recording medium is difficult. It has the drawback of being low. Further, in the method of (3), since the heat-sensitive layer is attached to another base material while being in a wet state and dried, lumpiness and curling are likely to occur, and the thickness of the heat-sensitive layer becomes nonuniform, and uneven printing is likely to occur. . Further, since it is dried through the substrate, there is a drawback that the drying speed is slow and the efficiency is low in manufacturing.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a double heat-sensitive recording material in which two heat-sensitive recording materials are attached to each other. Curling, blistering and wrinkles are less likely to occur, and heat energy is applied from the surface. Both the upper and lower thermosensitive recording materials develop color, and uniform printing with less unevenness can be obtained. Further, the present invention relates to a method for efficiently producing such a double thermosensitive recording medium.

[0005]

A double thermosensitive recording medium according to the present invention comprises a support A, a thermosensitive color recording layer A, an active energy ray curable resin layer, and an interface with the active energy ray curable resin layer. A peelable support B and a thermosensitive color recording layer B are provided in this order. Further, at least one intermediate layer made of an aqueous composition may be provided between the thermosensitive color recording layer A and the active energy ray-curable resin layer. It is also preferable that the support B is a synthetic resin film.

In the method for producing a double thermosensitive recording medium according to the present invention, the thermosensitive color recording layer A is provided on the support A, and an intermediate layer made of an aqueous composition is further provided, if necessary. Alternatively, the intermediate layer and the support B are bonded together by using an active energy ray-curable resin layer, and the active energy ray-curable resin layer is cured by irradiation with an active energy ray, and then the thermosensitive color-developing recording layer is formed on the support B. B is provided. Further, a support in which a thermosensitive color recording layer A is provided on the support A, an intermediate layer made of an aqueous composition is further provided if necessary, and the thermosensitive color recording layer A or the intermediate layer and the thermosensitive color recording layer B are provided in advance. B may be bonded using an active energy ray-curable resin layer, and the active energy ray may be irradiated to cure the active energy ray-curable resin layer. In the above manufacturing method, it is preferable to use an electron beam as the active energy ray.

[0007]

The support A of the thermosensitive recording medium in the present invention is not particularly limited as long as it is a flexible sheet-like material. For example, various commonly known coated papers, fine papers, synthetic papers, metallized papers, etc. Paper sheets such as paper and colored paper; plastic films such as polyethylene terephthalate, polypropylene and polyethylene; metal foils such as copper, iron and aluminum; cloth and the like, or a laminated body and a laminated body thereof are appropriately used. . The thickness of the support A is not particularly limited, but about 10 to 500 μm is suitable from the viewpoint of easy handling.

As the support B, the same one as the support A can be used. However, the better the smoothness of the surface of the support B bonded to the thermosensitive recording medium A, the more smooth and strong glossy surface is formed on the thermosensitive recording medium A when the thermosensitive recording medium B is peeled off, which is preferable. . Further, it is preferable that the surface of the support B to be bonded to the thermal recording medium A has good releasability from the cured film of the active energy ray-curable resin. That is, at least when the heat-sensitive recording material B is peeled off, the support B and the active energy ray-curing resin are cured so that the cured film of the active energy ray-curable resin remains on the surface of the heat-sensitive color recording layer A or the intermediate layer surface. The peeling force between the film and the active energy ray-curable resin cured film needs to be smaller than the peeling force between the surface of the thermosensitive color recording layer A or the surface of the intermediate layer.
From the above points, as the support B, synthetic resin films are preferable, and examples thereof include synthetic resin films such as polyester, polycarbonate, polypropylene, polyethylene, polystyrene, polyvinyl chloride, and polyimide. Polyester films such as polyethylene terephthalate are the most preferable in view of the balance among peelability, heat resistance, strength and cost. When such a film is used as the support B and bonded with an active energy ray-curable resin and irradiated with an active energy ray, the smooth surface of the film is directly transferred to the active energy ray-curable resin cured film, An active energy ray-curable resin layer having a uniform thickness is obtained, and the surface becomes smooth. As a result, uniform and constant peelability can be obtained. Further, the peeling force can be freely controlled by appropriately selecting the types of active energy ray-curable resin and film. When a paper sheet is used as the support B without using such films, the surface contacting the active energy ray-curable resin layer is
It is necessary to apply a barrier agent such as starch or polyvinyl alcohol in order to prevent penetration of the resin and reduce the peeling force. The coating amount in this case is 0.1-5
About g / m ² is sufficient.

Further, after the heat-sensitive recording material B is peeled off, it is possible to prevent additional recording on the heat-sensitive recording material A for the purpose of falsification. The higher the smoothness of the surface of the cured film of the active energy ray-curable resin which becomes the recording surface of the thermal recording material A, and the lower the heat resistance of the active energy ray-curable resin, the more sticking is likely to occur. Such recording becomes difficult. Further, it is very preferable to use a general synthetic resin film for the support B in order to increase the smoothness.

On the contrary, when it is considered that further recording is positively performed on the thermal recording medium A after the thermal recording medium B is peeled off,
When making this recording possible direction, it suffices if the above-mentioned sticking does not occur. For that purpose,
It is preferable that the surface of the cured film of the active energy ray-curable resin that becomes the recording surface of the thermal recording material A is not so smooth. In other words, use a paper whose surface of support B is not as smooth as a general film, or a film whose surface is appropriately roughened by mixing a pigment or whose surface is appropriately roughened by sandblasting or the like. Is desirable. Further, in order to improve the recording suitability, it is also preferable to add a pigment or the like to the active energy ray curable resin. In this way, by selecting the type of the active energy ray-curable resin and the smoothness of the support B, it is possible to freely control the recording suitability of the thermal recording medium A after the thermal recording medium B is peeled off. Incidentally, unless special control is performed using a general active energy ray-curable resin, it may be considered that the recording aptitude of the thermal recording material A is rather deteriorated and the tampering prevention effect can be obtained.

The thickness of the support B is 3 to 50 μm, preferably 6 to 25 μm. If the thickness is less than 3 μm, wrinkles are likely to occur during bonding, which may cause a manufacturing problem.
Further, it may be easily broken during peeling. Also, 50 μm
If the thickness is thicker, the energy from the thermal head becomes difficult to be transmitted, and the color development sensitivity is likely to be significantly lowered. Next, the thermosensitive color-developing recording layer provided on the support A and the support B as described above will be described. The thermosensitive color recording layer contains a colorless or pale basic dye and an organic or inorganic coloring agent. The combination of the colorless or light-colored basic dye contained in the thermosensitive color-developing recording layer and the organic or inorganic colorant is not particularly limited, and may be a color reaction caused by contact between the two due to heat. Any combination can be used. For example, various types of basic dyes that are colorless or light-colored are known, and examples thereof include the following.

3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3,3-bis (p
-Dimethylaminophenyl) phthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrol-3-yl) -6-dimethylaminophthalide and other triallylmethane dyes, 4,4'-bis-dimethyl Aminobenzhydryl benzyl ether, N-halophenyl-leuco auramine, N-2,4,5-trichlorophenyl leuco auramine and other diphenylmethane dyes, benzoyl leuco methylene blue, p-nitrobenzoyl leuco methylene blue and other thiazine dyes, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran,
3-phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho (6 '
-Methoxybenzo) spiropyran, 3-propyl-spiro-dibenzopyran and other spiro dyes, rhodamine-B
-Lactam dyes such as anilinolactam, rhodamine (p-nitroanilino) lactam, rhodamine (o-chloroanilino) lactam, 3- (N-ethyl-Ni)
Pentyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexyl) amino-
6-Methyl-7-anilinofluorane, 3-dibutylamino- (N-methyl-N-cyclohexyl) amino-6
-Methyl-7-anilinofluorane, 3-diethylamino-6-methoxyfluorane, 3-diethylamino-7
-Methoxyfluorane, 3-diethylamino-7-chlorofluorane, 3- (N-ethyl-N-isoamylamino) -7- (o-chlorophenylamino) fluorane,
Fluorane dyes such as 3-pyrrolidino-6-methyl-7-p-butylphenylaminofluorane. Other examples include the colorless or light-colored basic dyes described in JP-A-3-79387.

Various kinds of inorganic or organic acidic substances which are colored by contact with a basic colorless dye are also known. Examples thereof include activated clay, acid clay, attapulgite, bentonite, colloidal silica and aluminum silicate. Acidic substance, 4-hydroxy-4'-isopropyloxydiphenyl sulfone, 4,4'-isopropylidenediphenyl (bisphenol A), 4-tert-butylphenol, 4-hydroxydiphenoxide, 4-hydroxyacetophenol, 4- ( In addition to zinc salt of 3-p-tolylsulfonylpropyloxy) salicylic acid, etc., JP-A-3-
Coloring agents described in No. 79387 can be mentioned.

In the present invention, the use ratio of the basic dye and the acidic substance in the recording layer is appropriately selected according to the kind. Generally, 1 to 50 parts by weight, preferably 1 to 10 parts by weight of an acidic substance is used with respect to 1 part by weight of a basic dye. To prepare a coating solution containing these substances, water is generally used as a dispersion medium, and stirring with a ball mill, attritor, sand mill, etc.
A basic dye and an acidic substance are dispersed together or separately by a pulverizer to prepare a coating liquid.

Examples of the water-soluble resin and / or the water-dispersible resin of the adhesive (binder) used in the coating liquid include the following substances. As water-soluble resin; starches, 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.

As the water-dispersible resin: styrene / butadiene copolymer emulsion, vinyl acetate-vinyl chloride-
Examples thereof include ethylene copolymer emulsions. The binder is used in an amount of 10 to 40% by weight, preferably 15 to 35% by weight, based on the total solids. In addition, in order to provide sufficient water resistance, it is preferable that the binder contains a water-dispersible resin in an amount of 50% by weight or more.

Further, various auxiliaries can be added to the coating liquid, for example, sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate / sodium salt, alginate, fatty acid metal salt and the like. Examples thereof include dispersants, benzophenone-based and triazole-based ultraviolet absorbers, other defoamers, fluorescent dyes, coloring dyes and the like.

If necessary, lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax and ester wax, kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth and fine anhydrous silica. , Inorganic pigments such as activated clay, and stearic acid amides, stearic acid methylenebisamides, oleic acid amides, palmitic acid amides, perfumed oleic acid amides, aliphatic acid amides such as coconut fatty acid amides, 1,2-diphenoxyethane,
1,2-bis (3-methylphenoxine) ethane, 1,
Ethers such as 2-bis (4-methylphenoxine) ethane, 1-hydroxy-2-naphthoic acid phenyl ester, dibenzyl lalephthalate, dibenzyl oxalate,
Esters such as bis (p-chlorobenzyl oxalate) and benzyl p-benzyloxybenzoate, aromatic compounds such as p-benzylbiphenyl and m-terphenyl, and various known heat-fusible substances are used as sensitizers. It can also be added.

The method of applying the heat-sensitive color forming recording layer is not particularly limited, and it can be formed according to a conventionally known and commonly used technique, for example, bar coating, air knife coating, rod blade coating, pure blade coating, short dwell. It is formed by a method of applying and drying a coating liquid by coating or the like. When a plastic film is used as a support, the coating efficiency can be increased by subjecting the surface to treatments such as corona discharge and electron beam irradiation. The coating amount of the coating liquid is also not particularly limited, but it is usually in the range of about ² to ²⁰ g / m ² , preferably about 3 to 15 g / m ² in terms of dry weight.

When the surface of the thermosensitive color-developing recording layer A and the support B are bonded together by using the active energy ray-curable resin, the thermosensitive color-developing recording layer A is provided on the thermosensitive color-developing recording layer A in order to impart a barrier property to the active energy ray-curable resin. It is preferable to provide an intermediate layer. Furthermore, the sticking prevention on the thermosensitive color recording layer B,
An overcoat layer may be provided to impart water resistance and chemical resistance.

The above-mentioned intermediate layer and overcoat layer are required to be formed from an aqueous coating composition in order to prevent fog of the thermosensitive color-developing recording layer and deterioration of color developability. This water-based coating composition contains a water-soluble resin and / or a water-dispersible resin as a main component, an intermediate layer as required, and an overcoat layer contains a pigment as an essential component. Examples of the water-soluble resin and / or the water-dispersible resin include the following substances.

As a water-soluble resin; completely 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, phthalic anhydride, anhydrous Reaction products with polyvalent carboxylic acids such as trimellitic acid and itaconic anhydride, or esterification products of these reaction products, and further vinyl acetate and maleic acid, fumaric acid, itaconic acid, crotonic acid, acrylic acid, methacrylic acid, etc. As a saponification product of a carboxy-modified polyvinyl alcohol, which is obtained as a saponification product of a copolymer of ethylenically unsaturated carboxylic acid, and a copolymer of vinyl acetate and an olefin sulfonic acid such as ethylene sulfonic acid and allyl sulfonic acid, or a salt thereof. Sulfonic acid obtained Sex polyvinyl alcohol, vinyl acetate and ethylene, propylene, isobutylene, alpha-octene, alpha-Dotesen, alpha-Okutadodesen like copolymers of olefins modified polyvinyl alcohol obtained by saponifying with olefins, vinyl acetate and acrylonitrile,
Nitrile-modified polyvinyl alcohol obtained as a saponification product of a copolymer with nitriles such as methacrylonitrile, an amide-modified polyvinyl alcohol obtained by saponifying a copolymer of vinyl acetate and acrylamide such as methacrylamide, Pyrrolidone-modified polyvinyl alcohol obtained by saponifying a copolymer of vinyl acetate and N-vinylpyrrolidone, a cellulose derivative such as methylcellulose, ethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, casein, gum arabic, oxidized starch, etherified starch, diester. There are starches such as aldehyde starch and esterified starch.

The water-dispersible resin includes styrene-butadiene copolymer emulsion, vinyl acetate-vinyl chloride-ethylene copolymer emulsion, methacrylate-butadiene copolymer emulsion and the like. Specific examples of pigments include inorganic carbonates 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, and styrene microballs. , Nylon powder, polyethylene powder,
Examples include urea / formalin resin fillers and organic pigments such as raw starch granules. Of these, kaolin is particularly preferable because it has excellent water resistance and barrier properties.

Further, in the coating liquid for forming the intermediate layer and the overcoat layer, if necessary, glyoxal, methylolmelamine, potassium persulfate, ammonium persulfate, sodium persulfate, ferric chloride, magnesium chloride, boric acid, ammonium chloride. Hardeners such as zinc stearate, calcium stearate, stearic acid amide, polyethylene wax, carnauba wax, paraffin wax, ester wax, and other lubricants may be added, if necessary.
Sodium dioctyl sulfosuccinate, sodium dodecylbenzene sulfonate, sodium lauryl alcohol sulfate / sodium salt, alginate, surfactants such as fatty acid metal salts, benzophenone-based, triazole-based UV absorbers, defoamers, fluorescent dyes, Various auxiliaries such as coloring dyes can also be added as appropriate. The coating liquid for forming the intermediate layer and the overcoat layer is generally prepared as an aqueous coating liquid, and if necessary, a mixer, an attritor,
After being sufficiently mixed and dispersed by a mixing / stirring machine such as a ball mill or a roll mill, it is coated on the thermosensitive recording layer by various known coating devices. After coating, it can be cured and dried by irradiating it with ultraviolet rays or electron beams.

When a curing agent is used in combination, the curing agent should be applied not only in the coating liquid for forming the intermediate layer and the overcoat layer, but also separately from the coating liquid for forming the intermediate layer and the overcoat layer. In addition, when separately applied, there is no need to worry about the pot life of the coating liquid, and there is an advantage that a strong curing agent can be selected. The coating amount of the coating liquid for forming the intermediate layer and the overcoat layer is not particularly limited, but if it is less than 0.1 g / m ² , the desired effect cannot be sufficiently obtained, and 10 g / m 2 ^If it exceeds ² , the recording sensitivity of the thermosensitive recording medium may be deteriorated. Therefore, the dry weight is generally 0.1 to 10 g / m ² , preferably 0.5 to 5 g / m ² .
It is adjusted in the range of about m ² .

The smoothness of the intermediate layer and the overcoat layer formed as described above is 50 to 5000 in terms of Beck's smoothness.
A range of about seconds is preferable. If it is less than 50 seconds, the recording density and image quality or in the case of an intermediate layer is apt to be insufficient in terms of barrier property, and if it is more than 5000 seconds, the adhesiveness to the bonding layer is easily lowered in the case of the intermediate layer, and in the case of the overcoat layer. The sticking prevention effect tends to decrease. In order to adjust to such a range of smoothness, surface smoothing treatment may be performed with a super calendar or the like, if necessary.

Next, the surface of the heat-sensitive color recording layer A or the intermediate layer on the heat-sensitive recording material A and the surface of the heat-sensitive recording material B (support B) on which the heat-sensitive color recording layer B is not provided are treated with an active energy ray curable resin. The method of bonding by using will be described. The active energy ray curable resin used for bonding is not particularly limited as long as it can be cured by irradiation with active energy rays, but there is no coloring of the thermosensitive coloring layer due to heating, no unevenness of the substrate, and no curling. From this point of view, it is preferable not to involve a drying step, and for this purpose, a solvent-free one is preferable. The viscosity of the resin is preferably about 10 to 10,000 cps, more preferably about 100 to 5,000 cps. If it is lower than 10 cps, the resin may exude during bonding, or the thermosensitive coloring layer or the intermediate layer may be impregnated, resulting in insufficient bonding, or coloring or desensitization of the thermosensitive coloring layer may occur. If it is higher, the coated surface becomes non-uniform, and it may be difficult to obtain a uniform bonded surface.

Active energy ray curing used for bonding
The coating amount of the mold resin is not particularly limited,
0.1 g / m²If less than, the desired effect can be sufficiently obtained.
Not possible, 15g / m²Recording on thermal recording media
Dry weight is generally used because it may reduce sensitivity.
0.1-15g / m², Preferably 0.5 to 10 g / m
²Adjusted in a range of degrees. Active energy ray hardening type tree
Fats are, for example, the monomers and oligomers shown below.
Alternatively, a mixture of these is used. (A) Radical-polymerizable monofunctional monomer Acrylic acid, ethyl acrylate, hexyl acrylate
2-ethylhexyl acrylate, 2-hydroxy
Ethyl acrylate, 2-hydroxypropyl acryl
, Tetrahydrofurfuryl acrylate, phenoki
Ciethyl acrylate, triloxyethyl acrylate
Nonylphenoxyethyl acrylate, tetrahydr
Rofurfuryloxyethyl acrylate, 1,3-dio
Xolan acrylate, phenoxydiethylene glyco
Acrylate, benzyl acrylate, butoxyethyl
Acrylate, cyclohexyl acrylate, disic
Lopentanyl acrylate, dicyclopentenyl acryl
Rate, glycidyl acrylate, carbitol acryl
Rate, isobornyl acrylate, etc. (B) Radical-polymerizable polyfunctional monomer 1,6-hexanediol diacrylate, neo-penti
Ruglycol diacrylate, diethylene glycol di
Acrylate, tripropylene glycol diacreyl
G, dicyclopentanyl diacrylate, butylene glycol
Cold diacrylate, pentaerythritol diacry
Rate, trimethylolpropane triacrylate,
Ropylene oxide modified trimethylolpropane triac
Relate, pentaerythritol triacrylate, diester
Trimethylolpropane tetraacrylate, dipenta
Erythritol hexaacrylate, caprolactone
Dipentaerythritol hexaacrylate, tetra
Methylol methane tetraacrylate etc. (C) Radical polymerizable oligomer (prepolymer) Polyester (poly) acrylate and urethane (poly)
Acrylate, Epoxy (poly) acrylate, Polio
(Poly) acrylate etc.

Further, 2-chloroethyl vinyl ether,
It is also possible to use cationically polymerizable monomers and / or oligomers such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, triethylene glycol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether. it can. A cation polymerization initiator is necessary when the cation polymerizable monomer and / or oligomer is added. The cationic polymerization initiator is not particularly limited as long as it is a substance that initiates cationic polymerization by irradiation with active energy rays, and examples thereof include diazonium salts, iodonium salts, sulfonium salts, metallocene compounds and the like. The amount of these cationic polymerization initiators added is 0.1 to 1 with respect to 100 parts by weight of the cationically polymerizable monomer or / and oligomer.
About 0 parts by weight is preferable, and if it is less than 0.1 parts by weight, the polymerization initiation ability tends to be insufficient, and if it is more than 10 parts by weight, not only the effect is saturated, but also the solubility of the cationic polymerization initiator deteriorates, There may be adverse effects such as poor transparency of the coating film.

If desired, various additives such as dyes, pigments, wetting agents, defoaming agents, dispersants, antistatic agents, leveling agents and lubricants may be added to the above-mentioned active energy ray-curable resin. It can be added as appropriate as long as the effect is not impaired. As the bonding method, 1) an active energy ray-curable resin is applied to the surface of the thermosensitive color recording layer A or the intermediate layer, and the surface of the thermosensitive recording body B (support B) without the thermosensitive color recording layer B is provided. 2) Bonding with an active energy ray curable resin, thermosensitive color recording layer B of thermosensitive recording medium B (support B)
3) The active energy ray-curable resin is applied to the surface of the thermosensitive color-developing recording layer A or the intermediate layer, and 3) the active energy ray-curable resin is applied to the surface of the thermosensitive color-developing recording layer A or the intermediate layer and the thermosensitive recording material B (support). A method may be mentioned in which the body B) is coated on both surfaces of the body B) on which the thermosensitive color recording layer B is not provided and is then laminated. The device used for bonding is not particularly limited,
Usually, it is carried out by passing it between two rolls (nip rolls) under appropriate pressure.

The thermosensitive color recording layer B provided on the support B
A) is provided after the thermosensitive recording medium A and the support B are bonded together, and b) after the thermosensitive color recording layer B is provided on the support B in advance,
Any method of sticking to the thermosensitive recording medium A may be adopted. When the support B is made considerably thin, if the thermosensitive color recording layer B is provided on the support B in advance, wrinkles and fluffiness may easily occur, which may make the operation difficult. In such a case, Adopting the method has the advantage that stable operation is easy. Further, if there is no problem in operation, it is preferable to use a film having very high heat resistance and strength, or to provide a thermosensitive color recording layer B on the support B in advance using a base material having a certain thickness. The method (3) has less loss, and is more easily applicable to the production of a large variety of small lots when it is desired to manufacture a product in which the support A and the thermosensitive color recording layer A are replaced with the same thermosensitive recording medium.

The method of applying the active energy ray-curable resin is not particularly limited, and a usual coating means such as a bar coater, a roll coater, an air knife coater, a gravure coater, an offset gravure coater or the like can be appropriately used. It is also possible to pretreat the coated surface and the bonded surface by corona discharge treatment, radiation treatment, plasma treatment or the like in advance to control the wettability and adhesion of the active energy ray-curable resin.

The active energy ray-curable resin is cured by subsequently irradiating the laminated body of the heat sensitive recording material A and the heat sensitive recording material B (support B) laminated as described above with active energy rays. As the active energy rays, ultraviolet rays,
Examples include electron beams, X-rays, and γ rays, but they are easy to handle and
From the viewpoint of safety, ultraviolet rays and electron beams are preferable. Especially in the case of electron beam, there is no problem in curability even with a substrate with excellent transparency and low transparency, less heat is generated, and fogging of the thermosensitive coloring layer (whiteness decrease due to coloring due to heat) is less, photo radical It is particularly preferable because it does not require the addition of a polymerization initiator and has various advantages such as low odor, light resistance, excellent storage stability of the coating composition, and high productivity.

When an electron beam is used, it is desirable to adjust the amount of the electron beam to be irradiated within the range of about 1 to 200 kGy as the absorbed dose. If it is less than 1 kGy, a sufficient irradiation effect cannot be obtained, and irradiation exceeding 200 kGy is not preferable because it may deteriorate the substrate such as papers and certain plastic films. As the electron beam irradiation method, for example, a scanning method, a curtain beam method, a broad beam method or the like is adopted, and the acceleration voltage at the time of irradiating the electron beam needs to be controlled by the thickness of the base material on the irradiation side. However, about 150 to 300 kV is suitable.

When ultraviolet rays are used as the active energy rays, it is necessary to incorporate a photoradical polymerization initiator into the coating composition. For example, thioxanthone, benzoin, benzoin alkyl ether xanthone, dimethylxanthone, benzophenone, anthracene, benzyl, 2 , 2-
Diethoxyacetophenone, benzyl dimethyl ketal, diphenyl disulfide, anthraquinone, 1-chloroanthraquinone, 2-ethylanthraquinone, 2-
One or more radical polymerization initiators such as ter-butylanthraquinone, N, N′-tetraethyl-4,4′-diaminobenzophenone and 1,1-dichloroacetophenone are appropriately mixed. The amount of the photo-radical polymerization initiator used is desirably adjusted within the range of 0.2 to 10% by weight, preferably 0.5 to 5% by weight, based on the total composition. As a light source for UV irradiation, 1 to 50 UV lamps (for example, several mmHg
Low, medium and high pressure mercury lamps with operating pressures of up to about 10 atmospheres), xenon lamps, tungsten lamps, etc. are used. When ultraviolet rays are used, it is difficult for the ultraviolet rays to pass through the opaque substrate, and thus it is necessary to irradiate from the substrate side having higher transparency (usually, the side of the thermal recording material B).

[0036]

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In addition, the part in an example shows a weight part.

Example 1 A coating solution prepared by mixing and stirring 45 parts of solution A, 80 parts of solution B, 50 parts of a 20% aqueous solution of oxidized starch, and 10 parts of water shown below as support A was 105 g / m 2. ^{A high-} quality paper of No. ² was coated and dried so that the coating amount after drying was 8 g / m ² to form a thermosensitive color recording layer A. [Preparation of solution A] 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-phenylaminofluorane 1
A composition consisting of 0 part, 5 parts of a 5% aqueous solution of methyl cellulose, and 30 parts of water was pulverized by a sand mill until the average particle size became 3 μm. [Preparation of solution B] 20 parts of benzyl 4-hydroxybenzoate,
A composition consisting of 5 parts of a 5% aqueous solution of methyl cellulose and 55 parts of water was pulverized with a sand mill until the average particle size became 3 μm.

Next, on the thermosensitive color recording layer A obtained as described above, 1000 parts of an 8% aqueous solution of acetoacetylated polyvinyl alcohol (trade name: Z-200, manufactured by Nippon Synthetic Chemical Industry), calcium carbonate ( Product Name: Softon 180
0, manufactured by Bihoku Kouka Co., Ltd.), a composition for an intermediate layer consisting of 100 parts of water and 100 parts of water is applied and dried so that the applied amount after drying is 3 g / m ^2, and further smoothed by a super calendar. An intermediate layer having a Bekk smoothness of 500 seconds was formed.

Next, electron beam curable resin (Ebecryl)
810; Daicel UCB) in a dry weight of 4 g / m
^It was applied so that it would be ² , and a polyethylene terephthalate film (E5001, 12 μm thickness, manufactured by Toyobo) serving as the support B was laminated with a laminator, and immediately thereafter, an electron beam irradiation device (electro curtain CB-150; manufactured by ESI). ) Is used as the absorbed dose at an accelerating voltage of 175 kV.
An electron beam of 0 kGy was irradiated from the polyethylene terephthalate film side.

Then, after subjecting the polyethylene terephthalate film to corona treatment, a composition similar to the above thermosensitive color recording layer was applied and dried so that the coating amount after drying was 5 g / m ² . A thermosensitive color recording layer B was formed, and a composition similar to the above-mentioned intermediate layer was applied and dried thereon so that the coating amount after drying was 2 g / m ² to obtain an overcoat layer.

Example 2 A high-quality paper of 105 g / m ^{2 serving as} a support A was coated in the same manner as in Example 1 with a coating amount after drying of 8 g / m ² of a thermosensitive color recording layer A and a coating amount after drying. Formed an intermediate layer of 3 g / m ² . Next, on a polyethylene terephthalate film (E5001, 12 μm thickness, manufactured by Toyobo) to be the support B,
After the corona treatment, a composition similar to the above heat-sensitive layer was applied and dried so that the coating amount after drying was 5 g / m ² to form a heat-sensitive color forming recording layer B. A composition similar to that of the intermediate layer was coated and dried so that the coating amount after drying was 2 g / m ² to obtain an overcoat layer.

Next, electron beam curable resin (Ebecryl)
810; manufactured by Daicel UCB Co., Ltd.) is applied to the intermediate layer so that the dry weight is 4 g / m ² , and the surface of the polyethylene terephthalate film on which the thermosensitive color recording layer B is not provided is laminated with a laminator. Immediately, using an electron beam irradiation device (Electro Curtain CB-150; manufactured by ESI), the absorbed dose was 3 at an accelerating voltage of 175 kV.
An electron beam of 0 kGy was irradiated from the surface side of the polyethylene terephthalate film on which the thermosensitive color recording layer B was provided.

Example 3 In Example 1, 26 g / m ² glassine paper was used in place of the polyethylene terephthalate film serving as the support B, and the surface of the glassine paper to which the electron beam curable resin was attached was covered with an electron beam. Polyvinyl alcohol (PVA117; made by Kuraray) so that the curable resin does not penetrate into the glassine paper
1 g / m ² was used, and Support A
A double thermosensitive recording medium was obtained in the same manner except that the electron beam curable resin was applied after the corona treatment on the intermediate layer.

Comparative Example 1 A thermosensitive color recording layer A having a coating amount after drying of 8 g / m ² was formed on a high-quality paper of 105 g / m ^{2 serving as} a support A in the same manner as in Example 1. Onto this, an 8% aqueous solution of acetoacetylated polyvinyl alcohol (trade name: Z-200, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was applied at a coating amount of 2 g / m ² after drying, and the same as Example 1 before drying. The polyethylene terephthalate film serving as the support B of 1. was attached and dried. Next, on the polyethylene terephthalate film,
After the corona treatment, a composition similar to the above thermosensitive color recording layer is applied and dried so that the coating amount after drying is 5 g / m ² , to form a thermosensitive color recording layer B. And the same composition as the above-mentioned intermediate layer, and the coating amount after drying was 2 g /
It was coated and dried so as to have an m ² thickness to form an overcoat layer.

Comparative Example 2 A thermosensitive color recording layer A having a coating amount after drying of 8 g / m ² was formed on a high-quality paper of 105 g / m ^{2 serving as} a support A in the same manner as in Example 1. On top of this, a composition consisting of 50 parts of a 5% aqueous solution of acetoacetylated polyvinyl alcohol (trade name: Z-200, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), 100 parts of aliphatic amide washes (Armide HT; manufactured by Lion Armor Co., Ltd.), and 200 parts of water. The material was applied and dried so that the applied amount after drying was 1 g / m ² , to prepare a thermosensitive recording medium (A). Next, after performing corona treatment on a polyethylene terephthalate film (E5001, 12 μm thickness, manufactured by Toyobo) to be the support B, a composition similar to the heat-sensitive layer of Example 1 was prepared.
Apply and dry so that the applied amount after drying is 5 g / m ² ,
A thermosensitive color recording layer B is formed, and a composition similar to that of the intermediate layer of Example 1 is further applied and dried thereon so that the coating amount after drying is 2 g / m ² to form an overcoat layer. A thermosensitive recording medium (B) was prepared. Next, the heat-sensitive recording material (B) was overlaid on the heat-sensitive recording material (A) and passed through a super calendar (calender pressure 40 kg / cm) for pressure bonding.

Comparative Example 3 A double thermosensitive recording medium was obtained in the same manner as in Comparative Example 2 except that 26 g / m ² glassine paper was used in place of the polyethylene terephthalate film serving as the support B.

Comparative Example 4 In the same manner as in Example 1, a thermosensitive color recording layer A having a coating amount after drying of 8 g / m ^{2 and} a coating amount after drying were applied to a high-quality paper of 105 g / m ^{2 serving as} a support A in the same manner as in Example 1. There was a heat-sensitive recording material (a) to form an intermediate layer of 3 g / m ^2. Next, a polyethylene terephthalate film (E5001,1 which becomes the support B)
2 μm thick, manufactured by Toyobo), and after the corona treatment, a composition similar to the above heat-sensitive layer was applied at a coating amount of 5 g / dry.
m ² is applied and dried to form a thermosensitive color recording layer B, and a composition similar to the above intermediate layer is further applied thereon so that the applied amount after drying is 2 g / m ^2. Then, an overcoat layer was formed to prepare a thermosensitive recording medium (B).
Next, the thermal recording material (B) was overlaid on the thermal recording material (A) (without pressure bonding).

[Evaluation] Gray scale (gradation) recording was performed on the thus obtained recording medium using a thermal printer (test printer equipped with a thermal head for sublimation transfer recording). After recording, the support B was peeled off at the interface between the electron beam curable resin layer or a corresponding layer such as a wax layer, and these recorded images were evaluated for the following items. The thermal recording material on the side of the support B is simply referred to as top paper, and the thermal recording material on the side of the support A is referred to as bottom paper. The results are shown in Table 1.

[Maximum Color Development Density] The maximum density of gradation recording was measured with a Macbeth densitometer (RD-100R type, manufactured by Macbeth Co.). The higher the value, the higher the recording density. [Surface glossiness] The glossiness was measured at an incident angle of 75 degrees. (JIS
According to P8142) [Printing unevenness] Printing unevenness in the maximum density portion of gray scale recording was visually determined. ◯: There is no print unevenness and uniform color development. ○ ': Printing is uneven, but the printing is legible. Δ: Printing unevenness is conspicuous and partial blurring is seen. X: Print unevenness is remarkable and a part where no color is developed is seen.

[0050]

[Table 1]

[Evaluation Results] In the heat-sensitive recording materials obtained in Examples 1 and 2, when the upper paper was peeled off after the heat-sensitive recording, a cured layer of the electron beam curable resin remained on the lower paper, and the surface thereof was the same as the upper paper. Since the surface of the polyethylene terephthalate film as the support was directly transferred, the surface was highly smooth and had a high gloss as shown in Table 1. Also, the color density of the lower paper was extremely high. The thermal recording material obtained in Example 3 was
Since the support of the top paper is paper and the smoothness is slightly inferior to the films used in Examples 1 and 2, the glossiness of the bottom paper is slightly inferior, but it is sufficient as compared to the comparative examples. It has a high gloss. Further, the used paper was 26 g / m ² (thickness 23 μm), which was thicker than the film (12 μm) of Examples 1 and 2 and had a high heat insulating property, and thus the color density was considerably low. Here, in the case of paper, those thinner than the above are generally difficult to manufacture and difficult to obtain. In each of the Examples, the cured layer of the electron beam curable resin and the release surface of the support B were stable, and the electron beam curable resin layer did not remain on the support.

In Comparative Example 1, when the upper paper was peeled off after the heat-sensitive recording, the polyvinyl alcohol film remained on the lower paper, but when dried after bonding, moisture was evaporated through the support of the lower paper, and Perhaps because of the uniform shrinkage, the bottom paper had fluffiness, the gloss was insufficient, and as a result, the color density was low. In Comparative Example 2, the slack of the lower paper was less than that in Comparative Example 1, but the adhesion between the upper paper and the lower paper was insufficient, and when peeled, the laminating layer remained on the upper paper or remained on the lower paper. Alternatively, the layers were peeled between layers, the peeling surface was unstable, and the glossiness of the lower paper was further insufficient. As a result, the color density was also lower. Comparative Example 3 is manufactured by the same method as Comparative Example 2, but since the paper is used as the support for the upper paper, the heat transfer is non-uniform. The gloss and color density were low. In Comparative Example 4, the top paper and the bottom paper were not in close contact with each other, and the gloss and color density of the bottom paper were very low.

[0053]

EFFECTS OF THE INVENTION The double thermosensitive recording medium of the present invention, in which the two thermosensitive recording media are bonded together, has less curling, swelling and wrinkling, and when heat energy is applied from the surface, both the thermosensitive recording media on the upper side and the lower side of the thermosensitive recording medium are formed. The color is developed, and uniform printing with less unevenness can be obtained. The upper thermosensitive recording medium can be easily peeled off, the peeled surface is stable, and the color density is extremely high.

Claims (6)

[Claims] 1. A support A, a thermosensitive color recording layer A, an active energy ray-curable resin layer, a support B releasable from the interface with the active energy ray curable resin layer, and a thermosensitive color recording layer B in this order. A double thermosensitive recording medium having. 2. The double thermosensitive recording medium according to claim 1, wherein at least one intermediate layer made of an aqueous composition is provided between the thermosensitive color recording layer A and the active energy ray-curable resin layer. 3. The double thermosensitive recording medium according to claim 1, wherein the support B is a synthetic resin film. 4. A thermosensitive color recording layer A is provided on a support A,
If necessary, an intermediate layer composed of an aqueous composition is further provided, and the thermosensitive color-developing recording layer A or the intermediate layer and the support B are bonded together by using an active energy ray-curable resin layer, and the active energy ray is irradiated to activate the active energy ray. The thermosensitive color-developing recording layer B is provided on the support B after curing the line-curable resin layer.
2. The method for producing a double thermosensitive recording medium according to 2 or 3. 5. A thermosensitive color-developing recording layer A is provided on a support A,
Further, an intermediate layer made of an aqueous composition is optionally provided, and the thermosensitive color recording layer A or the support B having the thermosensitive color recording layer B previously provided thereon is bonded using an active energy ray-curable resin layer. The method for producing a double thermosensitive recording medium according to claim 1, 2 or 3, wherein the active energy ray-curable resin layer is cured by irradiation with an active energy ray. 6. The method for producing a double thermosensitive recording medium according to claim 4 or 5, wherein the active energy ray is an electron beam.