JP3053130B2 - Thermal recording medium and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is excellent in recording properties such as water resistance, oil resistance or chemical resistance such as organic solvent resistance, abrasion resistance, anti-sticking property and smoothness and recording preservability. It relates to a thermal recording medium.

[0002]

2. Description of the Related Art In recent years, in a wide range of fields such as facsimile machines, printers and recorders of various measuring instruments, printers for labels, printers for POS, and vending machines for tickets, etc., heat-sensitive recording materials for recording by thermal energy have been developed. It has come to be used. However, the general heat-sensitive recording layer has a drawback that it develops color or desensitizes upon contact with a solvent. In addition, they have insufficient water resistance and abrasion resistance, so that they cannot be used as such as label thermal recording media attached to fresh foods and the like, and have the disadvantage that they are colored by a slight scratch. At present, a heat-sensitive recording medium having enhanced water resistance, oil resistance, and scratch resistance has been desired. As a method of solving such a drawback, a method has been proposed in which a resin having a film forming ability is smeared on a heat-sensitive recording layer, and a recorded image is prevented from disappearing by physically separating the resin from a substance having a desensitizing property. . JP-A-54-128347 discloses a method of applying a water-soluble emulsion of a chemical-resistant resin having a film-forming ability onto a heat-sensitive recording layer, and JP-A-56-125354 discloses a method of coating a water-soluble emulsion such as polyvinyl alcohol. A method in which a molecular compound is smeared on a heat-sensitive recording layer, and a method in which a resin component smeared on a heat-sensitive recording layer is cured by an electron beam to form a resin layer has been proposed in JP-A-58-177392. ing.

[0003] However, even if improvements are made using these methods, new problems arise, and at present, sufficient results have not been obtained. For example, when providing a water-soluble resin overcoat layer on the heat-sensitive recording layer, it is very difficult to control the temperature at the time of drying, and if the drying temperature is too high, the background fog occurs, and if the drying temperature is too low, the resin component is too low. Is insufficiently cured, which causes scum generation and causes sticking (adhesion to a recording head) under high humidity conditions. In addition, even if an overcoat layer of an electron-curable resin is provided on the heat-sensitive recording layer, the contact between the color former and the developer is impeded due to the infiltration of the resin component into the heat-sensitive recording layer, and the color density is reduced. There has been a problem in that a reduction (desensitization effect) is caused and sticking is caused to cause printing trouble, or there is a problem that color development (fog) occurs due to an electron beam curable resin. As a means for solving the above problems, there is a method of providing an intermediate layer containing a water-soluble resin as a main component on a heat-sensitive recording layer, and further overcoating the intermediate layer with an electron beam-curable resin. JP 6
It is disclosed by Japanese Patent Application Laid-Open No. 2-279980. By this method, it is possible to prevent the desensitizing effect for the penetration of the electron beam curable resin into the heat-sensitive recording layer,
The color development (background fog) of the heat-sensitive recording layer due to the heat generated during the curing of the electron beam-curable resin, which was inevitable in the process of curing the resin by electron beam irradiation by directly providing the electron beam-curable resin on the heat-sensitive recording layer. It also had the effect of being suppressed.

However, in the method using such a water-soluble resin as the intermediate layer, the intermediate layer must be heated and dried before the application of the electron beam-curable resin. The same problem as in the case of providing the overcoat layer was caused. That is, it is very difficult to control the temperature during drying, and if the drying temperature is too high, fogging of the background will occur. Poor adhesion with resin. Also, when the thickness of the intermediate layer is thin, pinholes are likely to occur, and when an overcoat layer made of an electron beam curable resin is provided, only the pinholes are colored or when the thickness of the intermediate layer is increased to avoid the pinholes, Due to the heat shielding by the intermediate layer, there arises a problem that the print density is lowered particularly at low energy.

The present inventors have previously found the following means to solve the above-mentioned problems. That is, on the heat-sensitive recording layer of the heat-sensitive recording medium, a radiation-curable silicone resin layer having an action of preventing penetration of the overcoat resin is provided, and a radiation-curable overcoat resin layer is provided thereon. It is an invention of a recording medium. Here, the radiation includes ultraviolet rays, γ rays, and electron beams, and among them, ultraviolet rays and electron beams are preferable. The present invention
The fact that the radiation-curable silicone resin does not cause desensitization or fogging in the heat-sensitive recording layer, and that the radiation-curable silicone resin and the heat-sensitive recording layer have a very high affinity and are thin and uniform on the heat-sensitive recording layer The fact that the overcoat resin can be applied to the heat-sensitive recording layer regardless of whether it is cured or uncured. Is completely blocked, and the desensitization and fogging of the heat-sensitive recording layer by the overcoat resin can be prevented. According to this method, the silicone resin layer and the overcoat resin layer can be simultaneously cured by irradiation with radiation, and no thermal load is applied to the heat-sensitive recording layer, so that there is no background fog, and the silicone resin covers the surface of the heat-sensitive recording layer. Pinholes do not occur because they are completely covered and no heat shrinkage occurs. In addition, the process can be performed by a very simple process.

The present inventors have continued to study a method of manufacturing a thermosensitive recording medium using this silicone resin layer as an intermediate layer and providing a radiation-curable overcoat resin layer. Was revealed. That is, when a pigment is dispersed in a radiation-curable overcoat resin, for example, for the purpose of imparting anti-sticking properties, the viscosity of the radiation-curable resin increases, and especially when applied on a silicone resin intermediate layer, application by a coater is performed. Mixing of a viscosity modifier or a leveling agent as a surface smoothing agent in the overcoat resin may result in difficulties in controlling and / or impairing surface smoothness when the overcoat resin layer is cured by irradiation. May be required. However, general leveling agents (for example, fluorine compounds having a large leveling effect include fluoroalkyl carboxylic acid, perfluoroalkyl carboxylic acid, perfluorooctanesulfonic acid diethanolamide, N-propyl-N- (2-hydroxyethyl) perfluoro For silicone compounds such as octanesulfonamide, bis (N-perfluorooctylsulfonyl-N-ethylaminoethyl) phosphate, and monoperfluoroalkylethyl phosphate, amino-modified silicone oils, polyether-modified silicone oils, and olefin-modified silicone oils , Epoxy-modified silicone oil,
Alcohol-modified silicone oil, higher fatty acid-modified silicone oil, aromatic hydrocarbon-modified silicone oil,
The addition of an alkyl-modified silicone oil, a carboxy-modified silicone oil, a fluorine-modified silicone oil, etc.) contributes to lowering the viscosity of the overcoat resin and smoothing the surface of the overcoat resin layer. In particular, after heating and printing, a part of the leveling agent diffuses on the surface of the overcoat resin layer, causing crystallization to lower the apparent thermal recording density. in this way,
A commonly used leveling agent has advantages and disadvantages because the function as a leveling agent and the function as a thermal recording do not match.

[0007]

That is, the problem to be solved by the present invention is to provide a heat-sensitive recording medium while maintaining the properties of the silicone resin intermediate layer and the radiation-curable overcoat resin layer. The object of the present invention is to obtain a thermosensitive recording medium having improved surface smoothness, improved thermal recording accuracy, and improved sticking prevention.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies to improve the surface smoothness of a thermal recording medium provided with an overcoat resin layer and to improve the anti-sticking property. I found it. That is, a radiation-curable silicone resin intermediate layer , a polyester acrylate, and a polyester are provided on a heat-sensitive recording layer containing a color former and a color developer that comes into contact with the color former on a support.
Methacrylate, urethane acrylate, urethane meth
Acrylate, polyfunctional acrylate or polyfunctional methacrylate
Based on at least one radiation curable resin
Radiation containing radiation curable leveling agent
Characterized by having a curable overcoat resin layer
The invention is directed to a thermosensitive recording medium. Preferably, the radiation curing
Leveling agent is a polydialkylsiloxane molecule
An acryloyl group or methacrylate at the end or side chain of the main chain
Silicone resin with liloyl group introduced, radiation curable
Fluorine-containing acrylate resin or fluorine-containing methacrylate
Resin or radiation-curable acrylate-modified carbonized
Hydrogen surfactant or methacrylate modified hydrocarbon
Characterized by at least one of surfactants
It is an invention of a thermosensitive recording medium. In addition, on the heat-sensitive recording layer,
After providing the radiation-curable silicone resin intermediate layer,
Teracrylate, polyester methacrylate, urethane
Tanacrylate, urethane methacrylate, polyfunctional
Acrylate or polyfunctional methacrylate
Radiation-curable resin
Overcoat resin layer containing a leveling agent
After that, the silicone resin
Layer and the overcoat resin layer at the same time.
And a method for manufacturing a thermosensitive recording medium. The
Radiation-curable silicone resin interlayer on the thermal recording layer
After being provided, the radiation-irradiating silicone is irradiated with radiation.
After curing the resin interlayer, the polyester acryl
, Polyester methacrylate, urethane acryle
Acrylate, urethane methacrylate, polyfunctional acrylate, etc.
The other is the least also one of the multi-functional methacrylate radiation
Radiation curable leveling with curable resin as the main component
Irradiation with an overcoat resin layer containing an agent
For producing a thermosensitive recording medium characterized by curing by heat
The invention of the law. Here, the radiation-curable silicone resin is preferably a resin in which an acryloyl group or a methacryloyl group has been introduced into the terminal or side chain of the molecular main chain of polydialkylsiloxane. The overcoat resin layer containing the radiation-curable leveling agent here is a layer of a composition comprising the radiation-curable leveling agent and the radiation-curable resin. Hereinafter, in the present invention,
The overcoat resin layer containing a radiation-curable leveling agent is simply referred to as an overcoat resin layer, and is an overcoat resin layer containing a radiation-curable leveling agent unless otherwise specified.

The radiation-curable leveling agent referred to herein is preferably a radiation-curable silicone resin, a radiation-curable fluorine-containing acrylate resin or a fluorine-containing methacrylate resin, or a radiation-curable acrylate-modified hydrocarbon-based resin. It is a surfactant or a methacrylate-modified hydrocarbon-based surfactant. Here, the radiation includes ultraviolet rays, γ rays, and electron beams, and among them, ultraviolet rays and electron beams are preferable. A heat-sensitive recording medium of the present invention is obtained by providing a radiation-curable silicone resin intermediate layer and an overcoat resin layer on the heat-sensitive recording layer and curing by irradiation with radiation.The silicone resin intermediate layer and the overcoat resin layer are Each of them can be used alone or both layers can be simultaneously cured by irradiation. That is, after providing the radiation-curable silicone resin intermediate layer on the heat-sensitive recording layer, and before curing by radiation irradiation, a radiation-curable overcoat resin layer may be provided and both layers may be cured at the same time. After providing the hydrophilic silicone resin intermediate layer, curing may be performed by irradiation with radiation, and thereafter, an overcoat resin layer may be provided and cured. In particular, when the overcoat resin layer is provided before the silicone resin intermediate layer is cured, it is applied by a curtain coater or the like that can apply the overcoat resin layer without directly applying mechanical pressure to the existing silicone resin intermediate layer, Curing can be performed by irradiation with radiation.

Hereinafter, the present invention will be described in detail. As described above, when a leveling agent as a viscosity modifier or a surface smoothing agent is mixed into the overcoat resin, the addition of a general leveling agent reduces the viscosity of the overcoat resin and smoothens the surface of the overcoat resin layer. Although there is a contribution, there is a problem in the print density preservation after radiation curing,
The function as a leveling agent and the function as a thermal recording are not compatible. However, certain compounds have not only a sufficient leveling function for the electron beam curable composition, but also do not diffuse in the overcoat resin layer even after being cured by radiation, and are good even when subjected to thermal recording. Clarified the surprising fact that it has excellent recordability. Leveling agents having such good performance are all compounds having radiation curability, fluorine-containing compounds such as fluorine-containing acrylate or perfluoroalkyl acrylate, fluorine-containing methacrylate or perfluoroalkyl methacrylate, silicone-containing acrylate, Examples include silicone-containing compounds such as silicone-containing methacrylate or derivatives thereof, acrylate-modified hydrocarbon-based surfactants, and methacrylate-modified hydrocarbon-based surfactants. Hereinafter, typical electron beam-curable leveling agents are listed.

1) General formula of fluorine-containing acrylate or perfluoroalkyl acrylate; CH2 = CHCOOCnH2nCmF2mH, CH2 = CHCO
A compound represented by OCnH2nCmF2m + 1. For example, 2,2,2-trifluoroethyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, 1H, 1H, 5H-octafluoropentyl acrylate, 1H, 1H, 2H, 2H-heptadecafluorodecyl acrylate , N- (n-propyl) -N- (β-acryloxyethyl) -perfluorooctylsulfonamide, perfluoroalkylethyl acrylate, and the like. The product name is VISCOAT 3F, VISCOAT 4F, VISCOAT 8
F, Viscote 17F (above, Osaka Organic Chemical Industry Co., Ltd.), EF-125M (Mitsubishi Metal Corporation), AE8
00, AE1014 and Hoe T 3605 (Hoechst Japan K.K.).

2) General formula of fluorinated methacrylate or perfluoroalkyl methacrylate; CH2 = C (CH3) COOCnH2nCmF2mH, CH2 =
A compound represented by C (CH3) COOCnH2nCmF2m + 1. For example, 2,2,2-trifluoroethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, 1H, 1H, 5H-octafluoropentyl methacrylate, 1H, 1H, 2H, 2H-heptadecafluorodecyl methacrylate , N- (n-propyl) -N- (β-methacryloxyethyl) -perfluorooctylsulfonic acid amide, perfluoroalkylethyl acrylate and the like.
The product name is VISCOAT 3MF, VISCOAT 4MF,
VISCOAT 8MF, VISCOAT 17MF (above, Osaka Organic Chemical Industry Co., Ltd.), EF-135M (Mitsubishi Metal Corporation), MAE-600, MAE-1014, MAE
-800, Hoe T 3606 (Hoechst Japan K.K.) and the like.

3) Silicone-containing acrylate, silicone-containing methacrylate or derivative thereof A resin containing an acryloyl group or a methacryloyl group introduced into the terminal or side chain of the molecular main chain of a general silicone resin (mainly polydimethylsiloxane). An acrylate, a silicone-containing methacrylate or a derivative thereof. Product names are FM0711, FM0721, FM0725, P
S583 (above, Chisso Corporation), KNS-5000
2, KNS-5100, KNS-5300, KP-60
0, X-62-7052, X-62-7100, X-6
2-7112, X-62-7140, X-62-714
4, X-62-7153, X-62-7157, X-6
2-7158, KNS-5200, X-62-716
6, X-62-7168, X-62-7177, X-6
2-7180, X-62-7181, X-62-719
2, X-62-7200 X-62-7203, X-62
-7205, X-62-7931, KM-875, X-
62-7296A / B, X-62-7305A / B, X
-62-7028A / B, X-62-5039A / B,
X-62-5040A / B (Shin-Etsu Chemical Co., Ltd.), RC149, RC300, RC450, RC
802, RC710, RC715, RC720, RC7
30 (or more, Goldschmidt), EBECRYL
350, EBECRYL1360 (Daicel UC
B Co., Ltd.).

4) Acrylate-modified hydrocarbon surfactants, methacrylate-modified hydrocarbon surfactants having an acryloyl group or a methacryloyl group at a terminal or side chain of a hydrocarbon chain, and a sulfonic acid at another terminal or side chain A surfactant having a salt or phosphate functional group. Trade names are H-3355N and H-3355S.
(Daiichi Kogyo Seiyaku Co., Ltd.).

These radiation-curable leveling agents are:
They can be used alone or in combination of two or more.

The proportion of these radiation-curable leveling agents in the overcoat resin layer varies depending on the type of radiation-curable resin, the type and amount of pigments contained, and other additives, but generally is 0%. 0.0001% to 30%. The expected leveling effect is not obtained when the proportion of the radiation-curable leveling agent is smaller than this range,
If the amount exceeds this range, the leveling effect is not improved, and there is no merit in cost.

In the present invention, the resin used for the radiation-curable silicone resin intermediate layer is the same resin as the radiation-curable silicone resin used as the aforementioned radiation-curable leveling agent. These radiation-curable silicone resins can be used alone or in combination of two or more.

Typical examples of the radiation-curable resin forming the overcoat resin layer used in the present invention include (1) polyester acrylate and polyester methacrylate, for example, Aronix M-530.
0, Aronix M-5400, Aronix M-55
00, Aronix M-5600, Aronix M-5
700, Aronix M-6100, Aronix M-
6200, Aronix M-6300, Aronix M
-6500, Aronix M-7100, Aronix M-8030, Aronix M-8060, Aronix M-8100 (all trade names of Toa Gosei Chemical Industry Co., Ltd.), Biscoat 700, Biscoat 3700 (all,
Osaka Organic Chemical Industry Co., Ltd.), Kayarad HX-2
20, Kayarad HX-620 (Nippon Kayaku Co., Ltd.)
(Product name).

(2) Urethane acrylate, urethane methacrylate, for example, Aronix M-1100, Aronix M-1200, Aronix M-1210,
Aronix M-1250, Aronix M-126
0, Aronix M-1300, Aronix M-13
10 (above, trade name of Toa Gosei Chemical Industry Co., Ltd.), VISCOAT 812, VISCOAT 823, VISCOAT 823 (above, trade name of Osaka Organic Chemical Industry Co., Ltd.), NK ester,
U-108-A, NK ester, U-4HA (all trade names of Shin-Nakamura Chemical Co., Ltd.) and the like.

(3) Monofunctional acrylate, monofunctional methacrylate, vinylpyrrolidone, for example, methyl acrylate, ethyl acrylate, butyl acrylate, 2-
Ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2
-Hydroxypropyl acrylate, tetrahydrofurfuryl acrylate, phenoxyethyl acrylate,
Cyclohexyl acrylate, cyclohexyl methacrylate, acryloyl morpholine, benzyl acrylate, glycidyl methacrylate, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N-diethylaminoethyl methacrylate, butoxyethyl acrylate, vinylpyrrolidone, and the like. Ethylene oxide-modified phenoxylated phosphoric acid acrylate Ethylene oxide-modified butoxylated phosphoric acid acrylate, as well as Alonix M-101 and Aronix M-1 in trade names of Toa Gosei Chemical Industry Co., Ltd.
02, Aronix M-111, Aronix M-11
3, Aronix M-114, Aronix M-11
7, Aronix M-152, Aronix M-154
And the like.

(4) Polyfunctional acrylate, polyfunctional methacrylate, for example, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate,
Neopentyl glycol diacrylate, diethylene glycol diacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polypropylene glycol diacrylate, polypropylene glycol dimethacrylate, pentaerythritol diacrylate, dipentaerythritol hexaacrylate, isocyanuric acid diacrylate, pentaerythritol triacrylate , Isocyanuric acid triacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, ethylene oxide-modified pentaerythritol tetraacrylate, propylene oxide-modified pentaerythritol tetraacrylate, propylene oxide-modified dipentaerythritol polyacrylate Relate, ethylene oxide-modified dipentaerythritol polyacrylate, such acrylate esters of pentaerythritol acrylate adduct. Speaking of trade names of Toa Gosei Chemical Industry Co., Ltd., Aronix M-210 and Aronix M-21
5, Aronix M-220, Aronix M-23
0, Aronix M-233, Aronix M-24
0, Aronix M-245, Aronix M-30
5, Aronix M-309, Aronix M-31
0, Aronix M-315, Aronix M-32
0, Aronix M-325, Aronix M-33
0, Aronix M-400, Aronix M-45
0, TO-458, TO-747, TO-755, TH
IC. TA2 and the like. These can be used alone or in combination of two or more.

The photoinitiators used in the present invention, particularly when using the ultraviolet curing method, include acetophenones such as di- and trichloroacetophenone, benzophenone, Michler's ketone, benzyl, benzoin, benzoin alkyl ether, benzyldimethyl ketal, There are methylthiuram monosulfide, thioxanthones, azo compounds, and the like, which are selected from the viewpoint of the type of polymerization reaction of the radiation-curable resin, stability, and suitability for an ultraviolet irradiation device. The amount of the photoinitiator to be used is usually O.O. It is in the range of 1-5%. A storage stabilizer such as hydroquinone may be used in combination with the photoinitiator.

The coating amount of the silicone resin intermediate layer and the coating amount of the overcoat resin layer are not limited, but are desirably thinner for the purpose of avoiding heat interruption, and preferably 0.2 g / m ² to 0.2 g / m ² . 20 g / m ^2, more preferably in the range of ^{0.5g / m 2 ~10g / m 2} . The method of applying the radiation-curable silicone resin and the resin forming the overcoat resin layer according to the present invention includes a gravure coater, a bar coater, a roll coater, an air knife coater, a U comma coater, an AKKU coater, a smoothing coater, and a microgravure coater. , Reverse roll coater, four or five roll coater,
Any coater such as a blade coater, a dip coater, a falling curtain coater, a slide coater, a die coater and the like may be used. Particularly when the overcoat resin layer is provided before the silicone resin intermediate layer is cured, the vertical free fall curtain coater and slide coater can apply the overcoat resin layer without directly applying mechanical pressure to the existing silicone resin intermediate layer. It can be applied by a die coater or the like and cured by irradiation with radiation.

The base paper used as a support of the thermosensitive recording medium of the present invention may be any of the raw materials usually used in papermaking, such as wood pulp, synthetic pulp, filler, sizing agent, paper strength enhancer, and dye. It is possible to use a polymer film, a fibrous substrate, nonwoven, synthetic paper as a support, or a laminated paper, a metal foil, or a metal foil obtained by laminating a synthetic resin on paper on one side or both sides. A product bonded to paper or a synthetic resin film is also possible.

The color former used in the present invention is not particularly limited as long as it is generally used for a pressure-sensitive recording material or a heat-sensitive recording material.

Specific examples are as follows: (1) Triarylmethane compounds 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (crystal violet lactone), 3,3-bis ( p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3-
(1,2-dimethylindol-3-yl) phthalide,
3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindol-3-yl) phthalide, 3, 3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-
Yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -5-dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -5 -Dimethylaminophthalide, 3-p
-Dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6-dimethylaminophthalide and the like.

(2) Diphenylmethane compounds 4,4'-bis-dimethylaminophenylbenzhydryl benzyl ether, N-halophenyl leuco auramine, N-2,4,5-trichlorophenyl leuco auramine and the like.

(3) Xanthene compounds rhodamine B anilinolactam, rhodamine B-p-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluoran, 3-diethylamino-7-octylaminofluoran, 3- Diethylamino-7-phenylfluoran, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-chloro-7-methylfluoran, 3-diethylamino-7- (3,4-dichloroanilino) fluoran, 3 -Diethylamino-7
-(2-chloroanilino) fluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3- (N
-Ethyl-N-tolyl) amino-6-methyl-7-anilinofluoran, 3-piperidino-6-methyl-7-anilinofluoran, 3- (N-ethyl-N-tolyl) amino-6 Methyl-7-phenethylfluoran, 3-diethylamino-7- (4-nitroanilino) fluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-propyl) amino-
6-methyl-7-anilinofluoran, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-cyclohexyl) amino-6 Methyl-7-anilinofluoran, 3
-(N-ethyl-N-tetrahydrofuryl) amino-6
-Methyl-7-anilinofluoran and the like.

(4) Thiazine compounds Benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue and the like.

(5) Spiro compounds 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-methylnaphtho- (3 -Methoxybenzo) spiropyran, 3-propylspirobenzopyran and the like.

These can be used alone or in combination of two or more.

As the developer used in the present invention, an electron-accepting substance generally used for a thermosensitive recording medium is used, and in particular, a phenol derivative, an aromatic carboxylic acid derivative or a metal compound thereof, N, N ' -A diarylthiourea derivative or the like is used. Of these, particularly preferred are phenol derivatives, specifically, 1,1-bis (p
-Hydroxyphenyl) propane, 2,2-bis (p-
(Hydroxyphenyl) propane, 2,2-bis (p-hydroxyphenyl) butane, 2,2-bis (p-hydroxyphenyl) hexane, bisphenolsulfone,
Bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-isopropyloxydiphenylsulfone, 3,4-dihydroxy-4'-methyldiphenylsulfone, diphenol ether, benzyl p-hydroxybenzoate, p -Propyl benzoate, butyl p-hydroxybenzoate and the like.

In the present invention, the binder used for forming the heat-sensitive recording layer includes starches, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, and the like.
Carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, sodium polyacrylate, acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid terpolymer, styrene / maleic anhydride Water-soluble adhesives such as alkali salts of acid copolymers, alkali salts of ethylene / maleic anhydride copolymers, polyvinyl acetate, polyurethane, polyacrylate, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer And latex such as methyl acrylate / butadiene copolymer and ethylene / vinyl acetate copolymer.

In order to further improve the sensitivity, N-hydroxymethylstearic acid amide may be used as a sensitizer.
Waxes such as stearic acid amide and palmitic acid amide, naphthol derivatives such as 2-benzyloxynaphthalene, biphenyl derivatives such as p-benzylbiphenyl and 4-allyloxybiphenyl, 1,2-bis (3-methylphenoxy) ethane, Polyether compounds such as 2,2'-bis (4-methoxyphenoxy) diethyl ether and bis (4-methoxyphenyl) ether. Carbonic acid or oxalic acid diester derivatives such as diphenyl carbonate, dibenzyl oxalate, and di (p-chlorobenzyl) oxalate can be added.

The organic and inorganic pigments contained in the heat-sensitive recording layer, silicone resin intermediate layer or overcoat resin layer include diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide,
Examples include zinc oxide, silicon oxide, participating aluminum, barium sulfate, zinc sulfate, clay, colloidal silica, aluminum hydroxide, urea-formalin resin, styrene beads, nylon powder, polyethylene powder, and starch.

In addition, zinc stearate as an auxiliary agent,
Higher fatty acid metal salts such as calcium stearate. Waxes such as paraffin, paraffin oxide, polyethylene, polyethylene oxide, stearamide, caster wax and the like. Further, a dispersant such as sodium dioctyl sulfosuccinate and sulfonic acid-modified polyvinyl alcohol, a benzophenone-based or benzotriazole-based ultraviolet absorber, a surfactant, a fluorescent dye, and the like are added as necessary.

In the heat-sensitive recording medium of the present invention, the heat-sensitive recording layer may be coated by a known coating method such as a blade coating method, an air knife coating method, a gravure coating method, a roll coating method, a bar coating method, and a drop curtain coating method. Methods are available. After drying, the heat-sensitive recording layer is preferably subjected to a smoothing treatment using a calender.

Further, a back coat may be applied to prevent curling and recording storability, a conductive treatment may be performed to prevent jamming, an undercoat layer may be provided between the support and the heat-sensitive recording layer, Various known techniques in the field of heat-sensitive recording material production can be added as necessary, such as providing an adhesive layer for use as a recording medium. For the purpose of giving the overcoat resin layer releasability and adhesiveness, a release layer and an adhesive layer can be further provided thereon.

As the ultraviolet irradiation device used in the present invention,
For example, there are a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, a metal halide lamp, and the like, and an ozone-less type that generates less ozone. Generally, a plurality of lamps having an output of 30 w / cm or more are used in parallel.

The electron beam irradiation used in the present invention is performed by using an electron beam accelerator having an acceleration voltage of 100 to 1000 KV, more preferably 100 to 300 KV, in terms of transmission power and curing power.
It is preferable that the absorbed dose in one pass be 0.5 to 20 Mrad. If the accelerating voltage or the amount of electron beam irradiation is lower than this range, the electron beam penetrating power is too low to sufficiently cure, and if it is higher than this range, not only does the energy efficiency deteriorate, but also the resin and additives Undesired effects such as decomposition of paper and reduction in strength of base paper appear.

The electron beam accelerator may be, for example, any of an electron curtain system, a scanning type, a double scanning type, and the like. In the electron beam irradiation step, a synthetic resin film on the overcoat layer,
The overcoat layer can be cured while transferring the surface shape of the overcoat layer by bringing a metal foil or a metal drum into close contact.

At the time of electron beam irradiation, if the oxygen concentration is high, the curing of the electron beam curable resin is hindered. Therefore, replacement with an inert gas such as nitrogen, helium or carbon dioxide is performed.
Irradiation is preferably performed in an atmosphere in which the oxygen concentration is suppressed to 600 ppm or less, preferably 400 ppm or less. Even in the case of ultraviolet irradiation, it is desirable to reduce the oxygen concentration.

The heat-sensitive recording material of the present invention includes a label having a pressure-sensitive adhesive layer on the back surface, a heat-sensitive magnetic recording material having a magnetic recording layer on the back surface, a heat-sensitive heat transfer material having a heat transfer layer on the back surface, The present invention can also be used for a thermosensitive recording material having a gradation property, a photographic thermosensitive material having photographic paper adhered to the back surface, and a recording material having an ink jet layer on the back surface. In addition, it is also possible to use a heat-sensitive recording medium on which character printing or tint block printing is performed on the heat-sensitive recording layer, and to provide a silicone resin intermediate layer and an overcoat resin layer according to the present invention thereon.

[0044]

In the present invention, a radiation-curable silicone resin intermediate layer and an overcoat resin containing a radiation-curable leveling agent are provided on the thermal recording layer of the thermal recording medium. Due to the presence of the silicone resin intermediate layer, the overcoat resin does not penetrate into the heat-sensitive recording layer regardless of whether the silicone resin is cured or not, so that the heat-sensitive recording layer does not desensitize or fog. Due to the presence of the overcoat resin layer, the heat-sensitive recording layer is given water resistance, oil resistance, and chemical resistance while maintaining good heat-sensitive recording characteristics. In addition, by including a radiation-curable leveling agent in the overcoat resin layer, it is easy to apply a thin layer of the overcoat resin layer, the surface smoothness is improved, the sticking property to the thermal head is improved, and the curl characteristics are improved. Become good. Therefore, the thermal recording accuracy is improved, and better thermal recording characteristics can be obtained. Furthermore, since the leveling agent is radiation-curable, it imparts a leveling function to the overcoat resin at the time of coating, and when the overcoat resin layer is cured by irradiation, the leveling agent itself has a radiation-curable property. At the same time, and is fixed in the overcoat resin layer, so that it does not bleed out to the surface due to aging or heating, and therefore does not impair the heat-sensitive recording property and the heat-sensitive recording storage property. In addition, since the silicone resin intermediate layer and the overcoat resin layer are both cured by irradiation, the thermal recording medium does not suffer thermal damage, and the unevenness of the moisture in the thermal recording medium does not occur. Since generation is suppressed and thermal contraction of the resin layer does not occur, pinholes do not occur. Further, a thermal recording medium having an overcoat resin layer can be obtained by a very simple process.

[0045]

Next, the present invention will be described in more detail with reference to examples. Note that all parts and percentages shown below are based on weight. The value indicating the amount of application is the amount of application after drying unless otherwise specified.

Preparation Example 1 A mixture having the following composition was pulverized and dispersed by a sand mill until the average particle size became about 1 μm, and [Solution A] and [B
Liquid] was prepared. [Solution A] 3- (N-methyl-N-cyclohexyl) amino-6-
Methyl-7-anilinofluoran
42 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 40 parts [Solution B] Bisphenol A 52 parts 2-benzyloxynaphthalene 50 parts 10% aqueous solution of polyvinyl alcohol 50 parts Water 100 parts Next, [Solution A] [Solution B] was used. A heat-sensitive coating solution was prepared with the following composition. [Solution A] 50 parts [Solution B] 250 parts Zinc stearate (40% dispersion) 25 parts 10% aqueous solution of polyvinyl alcohol 216 parts Calcium carbonate 50 parts Water 417 parts

Example 1 A 50 g / m ² high-quality paper was coated with the heat-sensitive coating solution prepared in Preparation Example 1 so that the dry weight was 6 g / m ² , dried and then supercalendered to obtain a heat-sensitive recording material. . On the heat-sensitive recording layer of the obtained heat-sensitive recording medium, an electron beam-curable resin silicone resin (trade name: x-
62-7200) at an application amount of 0.6 g / m ² ,
Nitrogen-substituted electron beam irradiator (Nissin High Voltage
To the electron beam acceleration voltage 200
Electron beam irradiation of 3 Mrad was performed under the conditions of kV and irradiation current of 20 mA to obtain a thermosensitive recording medium having a silicone resin intermediate layer.
Next, as a radiation-curable overcoat resin, polyester acrylate (equivalent mixture of ARONIX M309 and M-8060, trade names, manufactured by Toa Gosei Chemical Industry Co., Ltd.) 9
0 parts and an electron beam-curable silicone resin as a radiation-curable leveling agent (trade name: x-62-72, manufactured by Shin-Etsu Chemical Co., Ltd.)
00) 10 parts of the mixture was mixed with a die coater at 5 g / m
^The composition was coated on the silicone resin intermediate layer so as to obtain No. ^2, and cured by an electron beam irradiation device to obtain a thermosensitive recording medium.

Example 2 In the same manner as in Example 1, except that the electron beam-curable silicone resin was changed to an ultraviolet-curable silicone resin (KNS5300, manufactured by Shin-Etsu Chemical Co., Ltd.), and curing was carried out by an ultraviolet irradiation device. In the same manner as in Example 1, a thermosensitive recording medium having a silicone resin intermediate layer was obtained. Next, as a radiation-curable overcoat resin, polyester acrylate (trade name: Aronix M, manufactured by Toa Gosei Chemical Industry Co., Ltd.)
A mixture of 97 parts of an equivalent mixture of 309 and M-8060) and 2 parts of a radiation-curable leveling agent, perfluoroalkylethyl acrylate: C ₈ F ₁₇ C ₂ H ₄ OCOCH = CH ₂ , was added to a die coater at 5 g / m ² was applied onto the silicone resin intermediate layer and cured by an electron beam irradiation device to obtain a thermosensitive recording medium.

Example 3 In the same manner as in Example 1, an electron beam-curable silicone resin intermediate layer was provided, cured by electron beam irradiation, and a polyester acrylate (manufactured by Toa Gosei Chemical Industry Co., Ltd., Name Aronix M309
And a mixture of 90 parts of calcium carbonate and 4 parts of calcium carbonate, 5 parts of an acrylate-modified surfactant as a radiation-curable leveling agent, and 1 part of a photoreaction initiator (Irgacure 651 manufactured by Ciba Geigy). Was coated on the silicone resin intermediate layer at a concentration of 5 g / m ² using a die coater, and cured by an ultraviolet irradiation device to obtain a thermosensitive recording medium.

Example 4 In the same manner as in Example 1, the electron beam-curable silicone resin was changed to an ultraviolet-curable silicone resin (trade name: KNS5300, manufactured by Shin-Etsu Chemical Co., Ltd.). Polyester acrylate (Toa Gosei Chemical Industry Co., Ltd.)
90 parts of an equivalent mixture of Aronix M309 and M-8060), 90 parts of calcium carbonate and 4 parts of perfluoroalkylethyl acrylate, a radiation-curable leveling agent: C ₈ F ₁₇ C ₂ H ₄ OCOCH = CH ₂ 5 parts, light Reaction initiator (Circa Geigy, trade name Irgacure 651)
Change to 1 part of mixture and use a die coater for 5 g / m
^The composition was coated on the silicone resin intermediate layer so as to obtain No. ^2, and cured by an ultraviolet irradiation device to obtain a thermosensitive recording medium.

Example 5 In the same manner as in Example 1, an electron beam curable resin silicone resin (trade name: x-62-720, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied on the heat-sensitive recording layer of the heat-sensitive recording material using a gravure coater.
3) was applied at an application amount of 0.6 g / m ² , and was used as an overcoat resin without curing by irradiation with polyester acrylate (available from Toagosei Chemical Co., Ltd. under the trade name ARONIX M309 and M-8060 in an equal mixture). ) 80 parts and an electron beam curable resin silicone resin (trade name: x-
62-7200) An electron beam irradiator (manufactured by Nisshin High Voltage, Co., Ltd.) in which 20 parts of the mixture was applied onto a silicone resin intermediate layer at a concentration of 3 g / m ² using a vertical free-fall curtain coater and subjected to nitrogen substitution. 3Mr under the conditions of electron beam acceleration voltage 200kV and irradiation current 20mA.
Irradiation of ad was performed to cure the silicone resin intermediate layer and the overcoat resin layer at the same time to obtain a thermosensitive recording medium.

Example 6 In the same manner as in Example 1, an ultraviolet-curable silicone resin (KNS5300, manufactured by Shin-Etsu Chemical Co., Ltd., trade name: 0.6 g / m) was coated on the heat-sensitive recording layer of the heat-sensitive recording material using a gravure coater. Polyester acrylate (Equivalent mixture of Aronix M309 and M-8060, manufactured by Toa Gosei Chemical Industry Co., Ltd.) 90 as an overcoat resin without being cured by irradiation with a coating amount of ²
And 4 parts of calcium carbonate, 5 parts of an ultraviolet-curable silicone resin (KNS5300, manufactured by Shin-Etsu Chemical Co., Ltd.) as a radiation-curable leveling agent, and 1 part of a photoreaction initiator (Irgacure 651, manufactured by Ciba Geigy). The silicone resin intermediate layer and the overcoat resin layer were simultaneously cured by applying to the silicone resin intermediate layer at a concentration of 3 g / m ² using a die coater and irradiating with an ultraviolet ray using an ultraviolet irradiating apparatus with nitrogen substitution. A thermosensitive recording medium was obtained.

Comparative Example 1 A dry paper having a dry weight of 6 was applied to the same high quality paper of 50 g / m ² as in Example 1.
The thermosensitive coating solution prepared in Preparation Example 1 was smeared, dried and supercalendered to give a thermosensitive recording medium so as to have a g / m ² .

Comparative Example 2 A thermosetting silicone resin (trade name KL-8, manufactured by Shin-Etsu Chemical Co., Ltd.) was formed on the heat-sensitive recording layer of the heat-sensitive recording medium obtained in Comparative Example 1.
38) Low temperature curing type platinum catalyst (CATPL-8)
Of 1% by weight, and a solid content of 0.6 g /
m ^2, and heat-cured with a hot air circulating drier at 80 ° C. Thereafter, an electron beam-curable overcoat resin layer was provided in the same manner as in Example 1, and cured by electron beam irradiation to obtain a thermosensitive recording medium.

Comparative Example 3 Polyester acrylate (trade name: Aronix M309, manufactured by Toa Gosei Chemical Industry Co., Ltd.) was directly used as a radiation-curable overcoat resin on the heat-sensitive recording layer of the heat-sensitive recording medium obtained in Comparative Example 1 using a gravure roll coater. And M-80
60 equivalent mixture) to 5 g / m ² .
The thermosensitive recording medium was obtained by curing with an electron beam irradiation device.

Comparative Example 4 A water-soluble resin composition was used as a water-soluble resin composition on the heat-sensitive recording layer of the heat-sensitive recording medium obtained in Comparative Example 1 using a gravure roll coater, PVA117 (trade name, manufactured by Kuraray Co., Ltd.).
1000 parts of aqueous solution, 100 parts of calcium carbonate and 10 parts of water
A solution consisting of 0 parts was applied so that the coating amount after drying was 1 g / m ^2, and then subjected to a super calendar treatment after thermal drying.
Polyester acrylate (equivalent mixture of ARONIX M309 and M-8060 manufactured by Toa Gosei Chemical Industry Co., Ltd.) as a radiation-curable overcoat resin thereon
A mixture of 95 parts and 5 parts of calcium carbonate was applied so as to be 5 g / m ^2, and cured by an electron beam irradiation device to obtain a thermosensitive recording medium.

Comparative Example 5 A thermosensitive recording medium was obtained in the same manner as in Comparative Example 4, except that the amount of the water-soluble resin composition after drying was 3 g / m ² .

Comparative Example 6 A thermosensitive recording medium was obtained in the same manner as in Comparative Example 4, except that the amount of the water-soluble resin composition after drying was 5 g / m ² .

Comparative Example 7 In the same manner as in Example 4, as a radiation-curable overcoat resin, polyester acrylate (trade name: Aronix M309 and M manufactured by Toa Gosei Chemical Industry Co., Ltd.) was used.
95 parts of calcium carbonate 4)
A thermosensitive recording medium was obtained in the same manner as in Example 4 except that a mixture of 1 part of a photoreaction initiator (trade name: Irgacure 651 manufactured by Ciba Geigy) was used.

Comparative Example 8 A thermosensitive recording medium was obtained in the same manner as in Example 1, except that only the leveling agent was replaced with polydimethylsiloxane carboxylate, which is a non-radiation-curable leveling agent. .

Comparative Example 9 In the same manner as in Example 2, only the leveling agent was changed to perfluoroalkylethanol having no radiation-curable functional group: C ₈ F ₁₇ C ₂ H ₄ OH, and thereafter Example 2 was used. In the same manner as in the above, a thermosensitive recording medium was obtained.

Comparative Example 10 A thermosensitive recording medium was obtained in the same manner as in Example 3, except that only the leveling agent was changed to an alkylsulfonic acid ester having no radiation-curable functional group. .

Test 1 (Print Density) Each of the heat-sensitive recording materials obtained in Examples 1 to 6 and Comparative Examples 1 to 9 was applied with a heat-sensitive printing tester using an applied pulse of 3.0 milliseconds and an applied voltage of 16.0 volts. After the print was developed under the conditions described above and stored at room temperature for 2 days, the color density of the obtained recorded image was evaluated using a densitometer Macbeth RD918. The results are shown in Table 1.

Test 2 (Sticking Test) The heat-sensitive recording materials obtained in Examples 1 to 7 and Comparative Examples 1 to 9 were
In the case of performing thermal printing using a thermal printing tester, the sticking property between the thermal head and the thermal recording medium was determined based on the printing sound. Based on the printing sound when the thermosensitive recording medium having no overcoat layer was continuously printed and colored, the sticking property was determined to be good when equal or better than the same. When the printing sound is clearly louder than the reference mark in the mark, or when there is an obstacle in the running of the thermosensitive recording medium due to sticking, the result is shown in Table 1 as a cross mark as poor sticking property.

Test 3 (Waterfastness) The background (uncolored portion) or the image recording portion (colored portion) of the thermosensitive recording medium obtained in Examples 1 to 6 and Comparative Examples 1 to 6 on a balance
Is fixed so that the heat-sensitive recording layer is on the top, a few drops of water are dropped on the heat-sensitive recording medium, and a silicon rubber stopper (diameter 2 cm) attached to the tip of the motor is loaded with a load of 600 g (pressure 191 g / c).
m), and the motor was rotated at a speed of 300 rpm for 4 seconds. At this time, peeling of the surface of the thermosensitive recording medium was visually judged, and when there was no change on the surface of the thermosensitive recording medium, the water resistance was determined to be good, and when peeling was observed on the surface of the thermosensitive recording medium, poor water resistance was observed. The results are shown in Table 1 with x marks.

Test 4 (Oil resistance) A few drops of castor oil were dropped on the image recording portion (colored portion) of each of the heat-sensitive recording media obtained in Examples 1 to 6 and Comparative Examples 1 to 6, and after 24 hours, the castor oil was wiped off. Thereafter, the density of the image recording portion was measured with a Macbeth densitometer, and a mark indicating that the decrease in print density was less than 0.03 points compared with the result of Test 1 was marked with a circle.
The results are shown in Table 1, in which the values of 0.03 points or more and less than 0.10 points are indicated by Δ, and those of 0.10 points or more are indicated by x.

Test 5 (resistance to organic solvent) A few drops of methyl ethyl ketone were dropped on the non-colored portions (background) of the heat-sensitive recording materials obtained in Examples 1 to 6 and Comparative Examples 1 to 6, and after one hour, they were wiped off. The results were measured with a densitometer and the results are shown in Table 1.

Test 6 (Surface Smoothness) Since the surface smoothness of the overcoat resin layer was observed as the density of the printed portion or the discontinuity of the thin line printed portion during thermal recording, Examples 1 to 6 and Comparative Examples 1 to 6 were performed. Observe with a microscope the colored portions of the vertical and horizontal thin lines of the thermosensitive recording medium obtained in Step 9, and mark those with good continuity of fine lines with ○ and those with discontinuous portions with fine lines with △. In Table 1, the results having a discontinuous portion in the thin line are represented by x marks.

Test 7 (Background Fog) The heat-sensitive recording media obtained in Examples 1 to 6 and Comparative Examples 1 to 9 were measured with a Macbeth densitometer without heat recording, and the results are shown in Table 1.

[0070] Test 8 (pinhole) a pinhole color heat-sensitive recording material was obtained in Examples 1 to 6 and Comparative Examples 1 to 9 were determined visually, if within several heat-sensitive recording surface of 1 m ² ○ with good pinhole property
When about 30 pinholes can be seen, mark 30
The results are shown in Table 1 with x marks when the number of the samples is more than one.

[0071]

[Table 1]

Evaluation: As is clear from the results in Table 1, a radiation-curable silicone resin intermediate layer was provided on the heat-sensitive recording layer as in the example, and a radiation-curable leveling agent containing a radiation-curable leveling agent was provided thereon. The thermal recording medium provided with the overcoat resin layer of the above shows good printing characteristics even in thermal recording at low energy, and the provision of the overcoat resin layer not only improves the scratch resistance but also improves the silicone resin intermediate property. In addition to the effect of the layer, chemical resistance such as water resistance, oil resistance and solvent resistance is improved. Although this is probably due to the heat insulating effect of the silicone resin intermediate layer, the heat of polymerization when the radiation-curable overcoat resin layer is cured is not directly transmitted to the heat-sensitive recording layer, and the background fog does not occur. Also, due to the good wettability of the silicone resin, no pinholes occur in the intermediate layer and the overcoat resin layer, and good curability even when the overcoat resin layer is applied on the uncured silicone resin intermediate layer, and A thermosensitive recording medium having good sticking properties and good recording characteristics can be obtained.
Further, by the action of the radiation-curable leveling agent contained in the overcoat resin layer, it is possible to obtain a heat-sensitive recording material having good surface smoothness, free from sticking, and having good thermal head running properties. The radiation-curable leveling agent is fixed in the layer when the overcoat layer is cured, so that the print density does not decrease even with the lapse of time, and exhibits good thermal recording properties.

Of the samples obtained as Comparative Examples, Comparative Example 1 had no overcoat resin layer at all, and thus had water resistance,
Poor organic solvent resistance. In Comparative Example 2, although the silicone resin intermediate layer was provided by thermosetting, desensitization of the heat-sensitive recording layer occurred and background fogging also occurred. When the radiation-curable overcoat resin layer is provided directly on the heat-sensitive recording layer as in Comparative Example 3, background fogging occurs due to heat of polymerization, and the chemical resistance is not as good as in the examples. When the intermediate layer is formed of a water-soluble resin as in Comparative Examples 4 to 6, the generation of pinholes is observed when the coating amount of the intermediate layer is small. If the coating amount of the water-soluble resin layer is increased to such an extent that the occurrence of pinholes becomes insufficient, the print density at low energy decreases and the recording characteristics deteriorate. Even if a silicone intermediate layer is provided as in Comparative Example 7, if the overcoat layer does not contain a leveling agent, the surface smoothness may be slightly inferior.
Although the surface properties are improved when the overcoat layer contains a leveling agent as in Comparative Examples 8 to 10, since the leveling agent is not fixed in the overcoat layer, the printing density which is considered to be caused by bleed-out of the leveling agent is reduced. Degradation occurs.

[0074]

The heat-sensitive recording material of the present invention has a high recording density, excellent water resistance and oil resistance, and has a background fog,
It has no pinhole coloring, has good surface smoothness, and has excellent heat-sensitive recording and record preservability.
After the heat-sensitive recording layer is provided in the manufacturing process, the high-temperature treatment is not performed, so that curling, wrinkles, pinholes, etc. can be suppressed, and the radiation-curable leveling agent is contained in the overcoat resin. It is possible to obtain a heat-sensitive recording material which is easy to apply a coat layer and has good sticking characteristics after curing.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-220791 (JP, A) JP-A-1-275183 (JP, A) JP-A-3-51180 (JP, A) JP-A-3-3180 166984 (JP, A) JP-A-5-8541 (JP, A) JP-A-5-177943 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/28-5 / 34

Claims (4)

(57) [Claims] 1. A radiation-curable silicone resin intermediate layer and a polyester acne on a heat-sensitive recording layer containing a color former and a color developer which comes into contact with the color former on a support.
Relate, polyester methacrylate, urethane ac
Related, urethane methacrylate, polyfunctional acrylate
Or at least one release of polyfunctional methacrylate
Ray curable resin as a main component, heat-sensitive recording material characterized by having a radiation curable overcoat resin layer containing a radiation-curable leveling agent. 2. The radiation-curable leveling agent is a silicone resin in which an acryloyl group or a methacryloyl group is introduced into a terminal or a side chain of a molecular main chain of polydialkylsiloxane, a radiation-curable fluorine-containing acrylate resin or a fluorine-containing methacrylate. The thermosensitive recording medium according to claim 1, wherein the thermosensitive recording medium is at least one of a resin, a radiation-curable acrylate-modified hydrocarbon-based surfactant, and a methacrylate-modified hydrocarbon-based surfactant. 3. After providing a radiation-curable silicone resin intermediate layer on the heat-sensitive recording layer, a polyester acrylate
G, polyester methacrylate, urethane acrylate
G, urethane methacrylate, polyfunctional acrylate or
Is at least one radiation hardened polyfunctional methacrylate
As a main component of resin, the overcoat resin layer containing a radiation-curable leveling agent is provided, and performs subsequent curing of the silicone resin intermediate layer and the overcoat resin layer by irradiation with simultaneous A method for producing a thermal recording medium. 4. After providing a radiation-curable silicone resin intermediate layer on the heat-sensitive recording layer, the radiation-curable silicone resin intermediate layer is cured by irradiation with radiation, and thereafter ,
Ester acrylate, polyester methacrylate,
Urethane acrylate, urethane methacrylate, multi-level
Acrylate or polyfunctional methacrylate
A method for producing a heat-sensitive recording material, comprising: providing an overcoat resin layer containing a radiation-curable resin as a main component and a radiation-curable leveling agent, and curing by radiation irradiation.