JPH0148156B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a heat-sensitive recording material, and particularly to a heat-sensitive recording material that has excellent printing stability. Conventionally, heat-sensitive recording materials that utilize a coloring reaction between a coloring agent and a coloring agent that develops color upon contact with the coloring agent, and obtain a colored image by bringing the two coloring materials into contact with each other using heat, are often used. Are known. Such thermosensitive recording media are relatively inexpensive, the recording equipment is compact, and maintenance is relatively easy, so they are used not only as recording media for facsimile machines and various computers, but also in a wide range of fields. However, such heat-sensitive recording materials generally have poor water resistance, oil resistance, and plasticizer resistance, so if, for example, water, oil, or plasticizers contained in the plastic film come into contact with the print after color development, the print density will be significantly reduced. It has the disadvantage of decreasing. Furthermore, it has a drawback in that it has poor resistance to organic solvents, and if organic solvents adhere to the background area where there is no printing, unnecessary coloring may occur. As a method to overcome these drawbacks, a method is proposed in which an aqueous emulsion of a resin having film-forming ability and chemical resistance is coated on the heat-sensitive recording layer (Japanese Patent Laid-Open Publication No.
54-128347) and a method of providing an ultraviolet curable resin layer (Japanese Unexamined Patent Publication No. 56-67293), etc., but improvements have been accompanied by new drawbacks, so satisfactory results have not always been obtained. is the current situation. That is, in the case of applying an aqueous emulsion of resin, the product tends to become bumpy, wrinkled, curled, etc., and the application speed must be limited to avoid color development due to high temperature drying, which poses difficulties in operability. be.
In addition, in the method of providing an ultraviolet curable resin layer, a photosensitizer such as benzophenone is required for curing the resin, which causes a strong odor during the curing process, and the odor also adheres to the product. Further, the pot life of the resin coating liquid is short, and it takes a long time for the resin to harden. In order to solve these difficulties, the inventors of the present invention have conducted extensive research on heat-sensitive recording materials with excellent print storage stability, and have found that the above-mentioned difficulties can be overcome by providing a resin coating layer on the recording layer by electron beam curing. resolved,
It was discovered that a recording medium with excellent water resistance, oil resistance, plasticizer resistance, and organic solvent resistance could be obtained very efficiently, and a patent application was previously filed as Japanese Patent Application No. 1983-60226. Subsequently, as a result of further intensive studies on such recording bodies, it became clear that simply providing a resin layer cured by electron beams may not be sufficient in some cases. That is, when water resistance and plasticizer resistance called water plasticizer resistance are required at the same time,
It has also been found that under extremely harsh conditions that require long-term oil resistance or organic solvent resistance, there is a risk that print density may decrease or unnecessary color development may occur. Therefore, as a result of further intensive research into heat-sensitive recording materials that have excellent print storage stability and do not produce unnecessary coloration even under the harsh conditions described above, we have found that a specific amount of By containing the pigment of
The present inventors have discovered that these difficulties can be overcome extremely efficiently, and have achieved the present invention. The present invention relates to a thermosensitive recording material having a resin coating layer cured by an electron beam on a thermosensitive recording layer containing at least a coloring agent and a coloring agent that develops a color when in contact with the coloring agent. Resin in the coating layer
This is a heat-sensitive recording material characterized by containing 5 to 300 parts by weight of pigment per 100 parts by weight. Although it is not clear why water plasticizer resistance etc. are significantly improved by incorporating pigments into the resin coating layer, for example, UV-curable resins, aqueous emulsions of resins, or water-soluble resins such as polyvinyl alcohol The above-mentioned excellent effects, which cannot be obtained even when pigments are added, are observed in the resin layer cured by electron beams of the present invention. Incidentally, when an ultraviolet curable resin is used, the curing speed of the resin film layer is significantly reduced because the pigment is used as an ultraviolet absorber. In addition, when using a water-based resin emulsion or water-soluble resin, it is necessary to dry at a low temperature to avoid color development in the recording layer, and a portion of the resin component permeates into the recording layer during the drying process, causing the pigment to fade. A sufficient barrier effect cannot be obtained probably because it is partially exposed. In the present invention, the color forming agent and coloring agent contained in the recording layer include a combination of a colorless or light-colored basic dye and an inorganic or organic acidic substance, and a combination of a higher fatty acid metal salt such as ferric stearate and a gallic acid. Examples include combinations of phenols such as acids, and the like. Among these, various types of colorless to light-colored basic dyes are known, and the following are exemplified. 3,3-bis(p-dimethylaminophenyl)
-6-dimethylaminophthalide, 3,3-bis(p-dimethylaminophenyl)phthalide, 3-
(p-dimethylaminophenyl)-3-(1,2-
dimethylindol-3-yl)phthalide, 3-
(dimethylaminophenyl)-3-(2-methylindol-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)-6-dimethylaminophthalide, 3,3-bis(2-phenylindole) -3-yl)-6-dimethylaminophthalide, 3
-p-dimethylaminophenyl-3-(1-methylpyrrol-3-yl)-6-dimethylaminophthalide and other triallylmethane dyes, 4,4'-bis-dimethylaminobenzhydryl benzyl ether, N-halofenyl-leucoauramine, N
- Diphenylmethane dyes such as 2,4,5-trichlorophenylleucoauramine, thiazine dyes such as benzoylleucomethylene blue and p-nitrobenzoylleucomethylene blue, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran , 3-phenyl-spiro-dinaphthrapine, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho(6'-methoxybenzo)spiropyran, 3-propyl-spiro-cibenzopyran, and other spiro dyes, Rhodamine-B-
Lactam dyes such as anilinolactam, rhodamine (p-nitroanilino)lactam, rhodamine (o-chloroanilino)lactam, 3-dimethylamino-7-methoxyfluorane, 3-diethylamino-6-methoxyfluorane, 3-diethylamino- 7-methoxyfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-
diethylamino-6,7-dimethylfluorane,
3-(N-Ethyl-p-toluidino)-7-methylfluorane, 3-diethylamino-7-N-acetyl-N-methylaminofluorane, 3-diethylamino-7-N-methylaminofluorane, 3
-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-N-methyl-N
-benzylaminofluorane, 3-diethylamino-7-N-chloroethyl-N-methylaminofluorane, 3-diethylamino-7-N-diethylaminofluorane, 3-(N-ethyl-p-toluidino)-6-methyl -7-phenylaminofluorane, 3-(N-ethyl-p-toluidino)-
6-methyl-7-(p-toluidino)fluoran,
3-diethylamino-6-methyl-7-phenylaminofluorane, 3-diethylamino-7-
(2-Carbomethoxy-phenylamino)fluoran, 3-(N-cyclohexyl-N-methylamino)-6-methyl-7-phenylaminofluoran, 3-pyrrolidino-6-methyl-7-phenylaminofluoran , 3-piperidino-6-methyl-7-phenylaminofluorane, 3-diethylamino-6-methyl-7-xylidinofluorane, 3-diethylamino-7-(o-chlorophenylamino)fluorane, 3-dibutyl Amino
7-(o-chlorophenylamino)fluoran,
Fluoran dyes such as 3-pyrrolidino-6-methyl-7-p-butylphenylaminofluoran. Various types of inorganic or organic acidic substances are also known that develop color upon contact with basic colorless dyes, for example, the following are exemplified. Inorganic acidic substances such as activated clay, acid clay, attapulgite, bentonite, colloidal silica, aluminum silicate, 4-tert-butylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, 4-hydroxyacetophenol, 4 -tert-octylcatechol, 2,
2'-Dihydroxydiphenol, 2,2'-methylenebis(4-methyl-6-tert-isobutylphenol), 4,4'-isopropylidenebis(2-
tert-butylphenol), 4,4'-sec-butylidene diphenol, 4-phenylphenol,
4,4'-isopropylidene diphenol (bisphenol A), 2,2'-methylenebis(4-chlorophenol), hydroquinone, 4,4'-cyclohexylidene diphenol, benzyl 4-hydroxybenzoate, 4-hydroxy Phenolic compounds such as dimethyl phthalate, hydroquinone monobenzyl ether, novolac type phenolic resin, phenolic polymer, benzoic acid, p-tert-butylbenzoic acid, triclobenzoic acid, terephthalic acid,
3-sec-butyl-4-hydroxybenzoic acid, 3
-cyclohexyl-4-hydroxybenzoic acid,
3,5-dimethyl-4-hydroxybenzoic acid, salicylic acid, 3-isopropylsalicylic acid, 3-
tert-butylsalicylic acid, 3-benzylsalicylic acid, 3-(α-methylbenzyl)salicylic acid, 3
-chloro-5-(α-methylbenzyl)salicylic acid, 3,5-di-tert-butylsalicylic acid, 3-
Aromatic carboxylic acids such as phenyl-5-(α,α-dimethylbenzyl)salicylic acid, 3,5-di-α-methylbenzylsalicylic acid, and these phenolic compounds, aromatic carboxylic acids such as zinc, magnesium, aluminum, calcium,
Organic acidic substances such as salts with polyvalent metals such as titanium, manganese, tin, and nickel. In the heat-sensitive recording material of the present invention, the ratio of the color former and color former in the recording layer is appropriately selected depending on the type of color former and color former used, and is not particularly limited. For example, when using a basic colorless dye and an acidic substance, generally 1 to 50 parts by weight, preferably 4 parts by weight, per 1 part by weight of the basic colorless dye.
~10 parts by weight of acidic substance are used. To prepare a coating solution containing these substances, generally water is used as a dispersion medium and a ball mill, attritor,
A coating liquid is prepared by dispersing the coloring agent and the coloring agent together or separately using a sand glider or other stirring or pulverizing machine. Such coating liquids usually contain starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, styrene/maleic anhydride copolymer salt, styrene/acrylic acid copolymer salt, Styrene-butadiene copolymer emulsion or the like is used in an amount of 10 to 40% by weight, preferably 15 to 30% by weight of the total solids. Furthermore, various auxiliary agents can be added to the coating liquid. For example, sodium dioctylsulfosuccinate, sodium dotesylbenzenesulfonate,
Examples include dispersants such as lauryl alcohol sulfate/sodium salt and fatty acid metal salts, ultraviolet absorbers such as benzophenone and triazole, antifoaming agents, fluorescent dyes, and coloring dyes. In addition, stearic acid, polyethylene, carnauba wax, paraffin wax, calcium stearate, waxes such as ester wax, kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, fine particulate anhydrous silica, activated Inorganic pigments such as clay, and sensitizers such as stearic acid amide, stearic acid methylene bisamide, oleic acid amide, palmitic acid amide, matcha oleic acid amide, and coconut fatty acid amide can also be added. In the heat-sensitive recording material of the present invention, there are no particular limitations on the method of forming the recording layer, and the recording layer can be formed according to conventionally well-known techniques, such as air knife coating, blade coating, etc. It is formed by applying and drying. The amount of coating liquid to be applied is also not particularly limited, but it is usually 2 to 12 g/m ² in terms of dry weight, preferably 3 to 10 g/m ²
is within the range of As mentioned above, the present invention has an important feature in that a resin coating layer containing a specific amount of pigment hardened by an electron beam is provided on the recording layer of a thermosensitive recording material. The formation is achieved by applying a coating agent consisting of a pigment and a resin component containing at least one prepolymer or oligomer having an ethylenically unsaturated bond, and curing it with an electron beam.
Such prepolymers or oligomers having ethylenically unsaturated bonds include unsaturated polyesters such as unsaturated polyesters, urethane-modified unsaturated polyesters, silicone-modified unsaturated polyesters, and epoxy-modified unsaturated polyesters, unsaturated polyethers, and acrylates. , polyester acrylate, epoxy acrylate, urethane acrylate, polyether acrylate, polyol acrylate, melamine acrylate, melamine urethane acrylate, silicone-modified acrylate, and other acrylates, methacrylate, polyester methacrylate, epoxy methacrylate, urethane methacrylate, polyether methacrylate, polyol methacrylate , methacrylates such as melamine methacrylate, melamine/urethane methacrylate, and silicone-modified methacrylate, prepolymers or oligomers such as vinyl polybutadiene, and alkyd resins, and copolymerization of two or more of these. Good too. As the resin component used in the present invention, in addition to the above-mentioned prepolymer, a vinyl monomer and a non-electron beam curable resin may be appropriately added as necessary within a range that does not impede the effects of the present invention. Such vinyl monomers include styrene, α
- off-line monomers such as methylstyrene;
Acrylic acid esters such as methyl acrylate, 2-ethylhexyl acrylate, methoxyethyl acrylate, butoxyethyl acrylate, butyl acrylate, methoxybutyl acrylate, cyanoacrylate, cyanoethyl acrylate, and phenyl acrylate; methyl methacrylate; Methacrylic acid esters such as propyl methacrylate, methoxyethyl methacrylate, ethoxymethyl methacrylate, phenyl methacrylate, ethyl methacrylate, and lauryl methacrylate; acrylamide, methacrylamide, N,N-dimethylacrylamide, N,N,-diisopropyl Acrylamide, N,N-didecyl acrylamide, N,N
-Unsaturated carboxylic acid amides and derivatives thereof such as dimethylmethacrylamide, N,N-diethylmethacrylamide; 2-(N,N-dimethylamino)methyl acrylate, 2-(N,
N-dimethylamino)ethyl, acrylic acid 2-
Compounds such as (N,N-dibenzylamino)ethyl, (N,N-dimethylamino)methyl methacrylate, 2-(N,N-diethylamino)propyl acrylate; ethylene glycol diacrylate, propylene glycol diacrylate, Neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, diethylene glycol diacrylate, triethylene glycol acrylate, dipropylene glycol diacrylate, ethylene glycol dimethacrylate,
Polyfunctional compounds such as propylene glycol dimethacrylate and diethylene glycol dimethacrylate can be mentioned. In addition, non-electron beam curable resins include acrylic resin, silicone resin, alkyd resin, fluororesin,
Examples include butyral resin. In the present invention, the pigment constituting the coating agent together with the resin component as described above is not particularly limited, but the following pigments can be exemplified. Inorganic pigments such as calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, silicon dioxide, aluminum hydroxide, barium sulfate, zinc sulfate, talc, kaolin, clay, calcined clay, colloidal silica, styrene microballs, nylon powder, polyethylene powder , raw starch granules, organic pigments such as zinc stearate, magnesium stearate, calcium stearate, and barium stearate, and these pigments in combination with fluorine, silicon, wax, higher fatty acids, organic titanates, silane coupling agents, and polymer resins. Pigments, etc. whose surfaces are coated or treated with compounds, organic acids, inorganic acids, etc. In the present invention, the pigment constituting a part of the coating agent is blended in an amount of 5 to 300 parts by weight, preferably 10 to 200 parts by weight, most preferably 20 to 100 parts by weight, based on 100 parts by weight of the resin component. It is something.
If the blending ratio of pigment is less than 5 parts by weight, sufficient effects cannot be obtained in terms of water plasticizer resistance, oil resistance, organic solvent resistance, etc., and if it exceeds 300 parts by weight, the film forming properties of the resin coating layer will be impaired. I end up. In the present invention, various auxiliary agents such as antifoaming agents, leveling agents, lubricants, surfactants, and plasticizers may be added to the coating agent as necessary. In the present invention, the coating agent containing resin components and pigments as main components is thoroughly mixed and dispersed using a mixing/stirring machine such as a mixer, attritor, ball mill, roll mill, etc., and then coated with a heat-sensitive recording material using a known coating device. applied on top of the layer. In order to maintain the viscosity of the coating agent within an appropriate range, the coating agent may be heated or a solvent may be added, if necessary, within a range that does not impede the effects of the present invention. The coating amount of the coating agent in the present invention is not particularly limited, but if it is less than 0.1 g/m ² , the desired effect of the present invention cannot be sufficiently obtained.
In addition, if it ^exceeds 20g/m2, the recording sensitivity of the thermal recording medium may be significantly reduced, so it is generally 0.1 to 20g/m2.
It is desirable to adjust the amount to 20 g/m ² , preferably in the range of 0.5 to 10 g/m ² . In the present invention, the electron beam accelerator used for curing the resin coating layer has a power of 50 to 1000 KeV,
Preferably, a device that generates an electron beam with an energy in the range of 100 to 500 KeV is desirable, such as a Kotscroft-Walton type, a Vande Graff type, a resonant transformer type, an insulated core transformer type, a linear type, a dynamitron type, a high frequency type, etc. An example is an electron beam accelerator. Further, the electron beam irradiation method is not particularly limited, and may be either a scanning method or an electrocurtain method. The irradiation dose of the electron beam in the present invention should be appropriately selected depending on the type and composition of the resin component used, the amount of application, etc., but if it is less than 0.1 Mrad, the resin component cannot be sufficiently cured.
If the radiation dose exceeds 15 Mrad, the heat-sensitive recording material may develop color or discolor, so it is desirable to carry out the treatment at an irradiation dose of 0.1 to 15 Mrad, preferably 0.5 to 10 Mrad. Thus, according to the present invention, a heat-sensitive recording material with excellent print storage stability can be obtained extremely efficiently by short-time electron beam treatment without the drawbacks of the prior art. The excellent effects of the present invention are achieved by providing a resin coating layer containing a specific amount of pigment on the recording layer by electron beam curing; however, an additional resin coating layer may be required. Depending on the situation, it is also possible to further improve the storage stability by providing it also on the back side of the heat-sensitive recording material. Further, the resin coating layer of the present invention can be provided over the recording layer, and may further include polyvinyl alcohol, methyl cellulose, hydroxyethyl cellulose, ethylene/acrylic acid copolymer salt, styrene/maleic anhydride copolymer salt, styrene·
Butadiene latex, acrylic latex,
It is also possible to provide the resin layer on a previously provided resin layer such as acetic acid viratex or electron beam curable resin. The present invention will be described in more detail with reference to Examples below, but it is of course not limited thereto. In addition, parts in the examples indicate parts by weight unless otherwise specified. Example 1 3-(N-cyclohexyl-N-
50 g of a coating liquid for a heat-sensitive recording layer prepared using methylamino)-6-methyl-7-phenylaminofluorane and bisphenol A as a coloring agent.
The mixture was smeared onto m ² of high-quality paper to a dry weight of 6 g/m ² and dried to obtain thermal recording paper. On the recording layer of the obtained thermosensitive recording paper, a coating agent having the following composition was applied. Coating agent composition: 30 parts of polyester acrylate prepolymer (Aronix M-8060, manufactured by Toagosei Co., Ltd.) (Aronix M-6300, manufactured by Toagosei Co., Ltd.) 35 After applying 35 parts of calcium carbonate (Softon 1200, manufactured by Bihoku Funka Co., Ltd.) using a hand-applied Meyer bar to a coating amount of 5 g/ ^m2 , an electrocurtain type electron beam irradiation device (manufactured by Inergy Science Co., Ltd.) was applied. , CB−150
The resin component was cured using a mold) at an irradiation dose of 3 Mrad to obtain resin-coated thermosensitive recording paper. Example 2 A resin-coated thermosensitive recording paper was obtained in the same manner as in Example 1 except that a coating agent having the following composition was used in Example 1. Coating agent composition Polyester acrylate prepolymer (Aronix M-8030, manufactured by Toagosei Co., Ltd.) 25 parts (Aronix M-6200, manufactured by Toagosei Co., Ltd.) 25 parts Calcium carbonate (Softon 1200, manufactured by Bihoku Funka Co., Ltd.) 50 parts Example 3 A resin-coated thermosensitive recording paper was obtained in the same manner as in Example 1 except that the coating agent in Example 1 had the following composition. Coating agent composition Polyester acrylate prepolymer (Aronix M-8060, manufactured by Toagosei Co., Ltd.) 40 parts (Aronix M-6200, manufactured by Toagosei Co., Ltd.) 40 parts Calcium carbonate (Softon 1200, manufactured by Bihoku Funka Co., Ltd.) 20 parts Example 4 A resin-coated thermosensitive recording paper was obtained in exactly the same manner as in Example 1, except that a coating agent having the following composition was used in Example 1. Coating agent composition Polyester acrylate prepolymer (Aronix M-8030, manufactured by Toagosei Co., Ltd.) 17 parts (Aronix M-6200, manufactured by Toagosei Co., Ltd.) 17 parts Calcium carbonate (Softon 1200, manufactured by Bihoku Funka Co., Ltd.) 64 parts Example 5 A resin-coated thermosensitive recording paper was obtained in the same manner as in Example 1 except that the coating agent in Example 1 had the following composition. Coating agent composition Polyester acrylate prepolymer (Aronix M-8030, Toagosei Co., Ltd.) 35 parts (Aronix M-6200, Toagosei Co., Ltd.) 35 parts Surface-treated calcium carbonate (Ryton
BK, manufactured by Bihoku Funka Co., Ltd.) 30 copies Example 6 A resin-coated thermosensitive recording paper was obtained in the same manner as in Example 1 except that the coating agent in Example 1 had the following composition. Coating agent composition Polyester acrylate prepolymer (Aronix M-8030, manufactured by Toagosei Co., Ltd.) 40 parts (Aronix M-6200, manufactured by Toagosei Co., Ltd.) 40 parts Silicon dioxide (Mizukashiru, manufactured by Mizusawa Chemical Co., Ltd.) 20 parts Example 7 Example 7 A resin-coated thermosensitive recording paper was obtained in the same manner as in Example 1, except that a coating agent having the following composition was used in Example 1. Coating agent composition Polyester acrylate prepolymer (Aronix M-1100, manufactured by Toagosei Co., Ltd.) 30 parts Polyester acrylate oligomer (Aronix M-1200, manufactured by Toagosei Co., Ltd.) 30 parts Calcium carbonate (Softon 1200, manufactured by Bihoku Funka Co., Ltd.) 40 parts Example 8 A resin-coated thermosensitive recording paper was obtained in the same manner as in Example 1 except that the coating agent used was as follows. Coating agent composition Polyester acrylate prepolymer (Ubicoat G, manufactured by Nippon Paint Co., Ltd.) 60 parts Calcium carbonate (Softon 1200, manufactured by Bihoku Funka Co., Ltd.) 40 parts Comparative example 1 Except for using the following composition as a coating agent in Example 1 A resin-coated thermosensitive recording paper was obtained in the same manner as in Example 1. Coating agent composition Polyester acrylate prepolymer (Aronix M-8060, manufactured by Toagosei Co., Ltd.) 50 parts (Aronix M-6200, manufactured by Toagosei Co., Ltd.) 50 parts Comparative example 2 Except for Example 1, where the coating agent had the following composition. A resin-coated thermosensitive recording paper was obtained in the same manner as in Example 1. Coating agent composition Polyester acrylate prepolymer (Aronix M-8030, manufactured by Toagosei Co., Ltd.) 5 parts Polyester acrylate oligomer (Aronix M-101, manufactured by Toagosei Co., Ltd.) 15 parts Calcium carbonate (Softon 1200, manufactured by Bihoku Funka Co., Ltd.) 80 parts Comparative Example 3 On the recording layer of a thermosensitive recording paper obtained in the same manner as in Example 1, diisobutylene, maleic anhydride copolymer salt (manufactured by Hitachi Chemical Co., Ltd., Aquasta HR-303) 40 parts (solid content), and ethylene were added.・Acrylic acid copolymer salt (manufactured by Seitetsu Kagaku Co., Ltd., Zaixen A) 40 parts (solid content) and calcium carbonate (Softon 1200, manufactured by Bihoku Funka Co., Ltd.)
A resin-coated thermosensitive recording paper was obtained by coating and drying 20 parts of a resin component to a dry weight of 5 g/m ² . The 11 types of thermal recording paper thus obtained were tested in a thermal gradient tester (manufactured by Toyo Seiki Co., Ltd., conditions: 130°C, 2 kg/
cm ² , 10 seconds), and the initial print color density was measured using a Macbeth densitometer (manufactured by Macbeth Co., Ltd., RD-
100R type, using an amber filter),
The results are shown in Table 1. Furthermore, the color density after each evaluation test of oil resistance, plasticizer resistance, water plasticizer resistance, and organic solvent resistance shown below was measured using a Macbeth densitometer, and the results are listed in Table 1. Oil resistance: Several drops of edible soybean oil were placed on the printed colored area, and after 24 hours, the soybean oil was wiped off with gauze, and the density of the printed area was measured. Plasticizer resistance: Polypropylene pipe (Fuji Polylene-PP, manufactured by Fuji Kako Co., Ltd., 40mmφ pipe)
A polyvinyl chloride wrap film (manufactured by Mitsui Toatsu Co., Ltd.) is wrapped three times on top of the film, a heat-sensitive recording paper with colored prints is placed on top of the film with the colored print side facing outward, and then a vinyl chloride wrap film is wrapped over the film. The film was wrapped five times, and the print density was measured after 72 hours. Water plasticizer resistance: Polypropylene pipe (Fuji Polylene-PP, manufactured by Fuji Kako Co., Ltd., 40mmφ pipe)
A vinyl chloride wrap film (manufactured by Mitsui Toatsu Co., Ltd.) was wrapped three times on top of the film, and heat-sensitive recording paper, which had been immersed in water for 5 seconds before coloring had been printed, was sandwiched on top of the film so that the colored side of the print was facing outward. Furthermore, a vinyl chloride wrap film was wrapped five times over it, and the print density was measured after 24 hours. Organic solvent resistance: Several drops of methyl ethyl ketone were placed on the skin, and after 30 minutes, the color density of the skin was measured.

[Table] As is clear from the results in Table 1, the heat-sensitive recording material according to the present invention was a recording material with extremely excellent print storage stability.

Claims (1)

[Claims] 1. In a thermosensitive recording material having a resin coating layer cured by an electron beam on a thermosensitive recording layer containing at least a coloring agent and a coloring agent that develops color when in contact with the coloring agent, in the resin coating layer. 5 to 300 parts by weight of pigment per 100 parts by weight of resin is contained in the heat-sensitive recording material.