JP4332457B2 - Thermal recording material - Google Patents

Description

  The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material that is excellent in light-resistant storage stability and light-recurrent color resistance of a red-colored color image.

  The heat-sensitive recording material generally comprises a heat-sensitive recording layer mainly comprising an electron-donating usually colorless or light-colored dye precursor and an electron-accepting color developer on a support, a thermal head, By heating with a thermal pen, laser light or the like, the dye precursor and the developer react instantaneously to obtain a recorded image (see, for example, Patent Documents 1 and 2). Such a heat-sensitive recording material is advantageous in that recording can be obtained with a relatively simple device, maintenance is easy, noise is not generated, measurement recorder, facsimile, printer, computer terminal, It is used in a wide range of fields such as label printing machines, boarding tickets, and ticket issuing machines.

  In recent years, in particular, thermal recordings such as receipts for gas, water, electricity bills, ATM usage statements for financial institutions, various receipts, etc., financial recording sheets, thermal recording labels or thermal recording tags for POS systems, etc. Materials are being used.

  As the use and demand of heat-sensitive recording materials expands in this way, color development other than general black color development or a combination of black color development and other color development has come to be required. In particular, there is an increasing demand for heat-sensitive recording materials capable of red color development.

  However, in general, a red color-developed image has a lower storage stability of a recorded image than a black color-developed image even in a monochrome color heat-sensitive recording material, and in particular, tends to be inferior in light-resistant storage stability. In addition, due to differences in heating conditions, multicolor thermosensitive recording materials that develop colors of two or more colors develop red, blue, green, etc. when printing on the low energy side, and black colors when printing on the high energy side. For this reason, the color development by printing on the low energy side does not form a necessary and sufficient color former. For this reason, a red color image printed on the low energy side has a lower storability of a recorded image than a black color image, and in particular, tends to be inferior in light-resistant storage stability.

  As described above, when the light resistance preservation property is inferior, when exposed outdoors or indoors through sunlight through a window, fluorescent light, etc., the deterioration of the recorded image due to light and the discoloration of the background increase, There is a strong demand for improvement in light-preserving stability because it may look out of date, or the contrast between the recorded image and the background becomes small, making it difficult to read. In addition, some of the tickets and tickets are used for purposes such as printing again after being exposed to sunlight or fluorescent lamps as described above. There is also a demand for improved light-recurring color resistance.

  As a means for enhancing the light fastness of a red color image in a heat-sensitive recording material, a method using a specific red color developing dye precursor and a binder resin soluble in an aromatic hydrocarbon solvent is described. (For example, refer to Patent Document 3) Since an organic solvent is used, there is a problem that safety and environmental load are large, and it is difficult to carry out by water-based coating which is a general thermal recording material coating method. is there.

  Further, as a method for improving the light resistance storage stability of the heat-sensitive recording material, a method of adding a specific antioxidant and an ultraviolet absorber is described (for example, see Patent Document 4), but sufficient light resistance storage stability is described. Is hard to say.

  In addition, a heat-sensitive recording material using a specific phenolic compound as an electron-accepting compound (see, for example, Patent Documents 5 and 6) has been proposed, and examples of several types of red coloring dye precursors are described. However, it is difficult to say that sufficient light resistance and light recurrence resistance are obtained.

On the other hand, a dye precursor particle in which a heat-sensitive recording layer is provided with a specific electron accepting compound, a red color forming dye precursor as an electron donating dye precursor, and a coating layer formed from an organic polymer on the surface of the dye particle Has been proposed (for example, see Reference 7), but it is difficult to say that the light-resistant storage stability of red-colored images is sufficient.
Japanese Patent Publication No.43-4160 Japanese Examined Patent Publication No. 45-14039 JP-A-8-175028 Japanese Patent No. 2727234 WO02 / 81229 WO01 / 25193 JP 2002-218707 A

  An object of the present invention is to provide a heat-sensitive recording material excellent in light-resistant storage stability and light-recurrent color resistance of a red-colored color image.

As a result of intensive studies, the present inventors have invented the heat-sensitive recording material of the present invention that can solve the problems. That is, in a heat-sensitive recording material provided with a heat-sensitive recording layer containing an electron-donating ordinary colorless or light-colored dye precursor and an electron-accepting compound that reacts when heated to develop a color of the dye precursor, At least as an electron-accepting compound, N- (2-hydroxyphenyl) -2-[(4-hydroxyphenyl) thio] acetamide and N- (4-hydroxyphenyl) -2-[(4-hydroxyphenyl) thio] acetamide contains at least one selected from an electron-donating reddish coloring dye precursor, 3, 3-bis (1-ethyl-2-methylindole-3-yl) phthalide及 beauty 3- (N A thermosensitive recording material comprising at least one selected from -ethyl-Np-tolyl) amino-7-methylfluorane.

  In a heat-sensitive recording material comprising an electron-donating compound, which is an electron-donating usually colorless or light-colored dye precursor, and an electron-accepting compound that develops a dye precursor when heated, the red color-forming dye precursor And at least one selected from N- (2-hydroxyphenyl) -2-[(4-hydroxyphenyl) thio] acetamide and N- (4-hydroxyphenyl) -2-[(4-hydroxyphenyl) thio] acetamide By combining various electron-accepting compounds, it is possible to obtain a heat-sensitive recording material that is excellent in light-resistant storage stability and light-recurring color resistance of red-colored developed images.

  Hereinafter, the content of the present invention will be described more specifically. The heat-sensitive recording material of the present invention has a heat-sensitive recording layer containing, on a support, an electron-donating compound that is an electron-donating usually colorless to light-colored dye precursor and an electron-accepting compound that reacts when heated to develop a color of the dye precursor. It is.

  As the support used in the present invention, paper is mainly used, but in addition to paper, various woven fabrics, non-woven fabrics, synthetic resin films, synthetic resin laminated papers, synthetic papers, metal stays, vapor deposition sheets, or bonding them together The composite sheet combined in (1) can be arbitrarily used depending on the purpose.

  As the electron-accepting compound for coloring the dye precursor constituting the heat-sensitive recording layer of the heat-sensitive recording material of the present invention, the aforementioned compounds are used.

  Specifically, N- (2-hydroxyphenyl) -2-[(4-hydroxyphenyl) thio] acetamide and N- (4-hydroxyphenyl) -2-[(4-hydroxyphenyl) thio] acetamide. In addition to these, N- (3-hydroxyphenyl) -2-[(4-hydroxyphenyl) thio] acetamide, N- (2-hydroxy-4-methylphenyl) -2-[(4-hydroxyphenyl) Thio] acetamide, N- (2-hydroxy-5-chlorophenyl) -2-[(4-hydroxyphenyl) thio] acetamide, N- (2-hydroxyphenyl) -2-phenylthioacetamide and the like can also be used.

  In addition, two or more of the above electron-accepting compounds can be used in combination. By the combined use, a heat-sensitive recording material that is further excellent in light-resistant storage stability and light-recurring color resistance can be obtained. Preferably, a combination of N- (2-hydroxyphenyl) -2-[(4-hydroxyphenyl) thio] acetamide and N- (4-hydroxyphenyl) -2-[(4-hydroxyphenyl) thio] acetamide is used. It is done. More preferably, a combined ratio of N- (2-hydroxyphenyl) -2-[(4-hydroxyphenyl) thio] acetamide and N- (4-hydroxyphenyl) -2-[(4-hydroxyphenyl) thio] acetamide Is in the range of 40:60 to 60:40 by mass ratio.

Further, the heat-sensitive recording material of the present invention, N- as an electron-accepting compound (2-hydroxyphenyl) -2 - [(4-hydroxyphenyl) thio] acetamide and N-(4-hydroxyphenyl) -2 - [( 4-hydroxyphenyl) thio] acetamide, which is characterized by containing at least one selected from the group consisting of one or more other electron-accepting compounds as long as the desired effects of the present invention are not impaired. Is also possible. The electron-accepting compound that can be used in combination is typically represented by an electron-accepting compound used in a pressure-sensitive recording material or a heat-sensitive recording material, but is not limited thereto. Examples thereof include phenol derivatives, aromatic carboxylic acid derivatives, N, N′-diarylthiourea derivatives, arylsulfonylurea derivatives, polyvalent metal salts such as zinc salts of organic compounds, and benzenesulfonamide derivatives.

  Specific examples include clay clays such as acid clay, activated clay, zeolite, bentonite and kaolin, p-phenylphenol, p-hydroxyacetophenone, 4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxy-4 '. -Isopropoxydiphenylsulfone, 4-hydroxy-4'-n-propoxydiphenylsulfone, 3-phenylsulfonyl-4-hydroxydiphenylsulfone, 4-hydroxy-4'-benzenesulfonyloxydiphenylsulfone, 1,1-bis (4 -Hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) pentane, 1,1-bis (4-hydroxyphenyl) hexane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-Hydroxyphenyl) cycl Dodecane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) hexane, 2,2-bis (4-hydroxyphenyl) octane, 1,1-bis (4-hydroxy) Phenyl) -2-ethylhexane, 2,2-bis (3-chloro-4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,3-di- [2 -(4-hydroxyphenyl) -2-propyl] benzene, 1,3-di- [2- (3,4-dihydroxyphenyl) -2-propyl] benzene, 1,4-di- [2- (4- Hydroxyphenyl) -2-propyl] benzene, 4,4'-dihydroxydiphenyl ether, N- (2-hydroxyphenyl) benzenesulfonamide, N- (2-hydroxy) Phenyl) -p-toluenesulfonamide, N- (4-hydroxyphenyl) benzenesulfonamide, N- (4-hydroxyphenyl) -p-toluenesulfonamide, 4,4'-dihydroxydiphenylsulfone, 2,4'- Dihydroxydiphenylsulfone, 3,3'-dichloro-4,4'-dihydroxydiphenylsulfone, 3,3'-diallyl-4,4'-dihydroxydiphenylsulfone, 3,3'-dichloro-4,4'-dihydroxydiphenyl Sulfide, methyl 2,2-bis (4-hydroxyphenyl) acetate, butyl 2,2-bis (4-hydroxyphenyl) acetate, 4,4'-thiobis (2-t-butyl-5-methylphenol), p -Benzyl hydroxybenzoate, chlorobenzyl p-hydroxybenzoate, 4-hydro Dimethyl xylphthalate, benzyl gallate, stearyl gallate, salicylanilide, 5-chlorosalicylanilide, novolac phenol resin, modified terpene phenol resin, 3,5-di-t-butylsalicylic acid, 3,5-di-t-nonyl Salicylic acid, 3,5-didodecylsalicylic acid, 3-methyl-5-t-dodecylsalicylic acid, 5-cyclohexylsalicylic acid, 3,5-bis (α, α-dimethylbenzyl) salicylic acid, 3-methyl-5- (α- (Methylbenzyl) salicylic acid and the like, and metal salts such as zinc, nickel, aluminum, calcium and the like can be mentioned, but are not limited thereto, and two or more kinds of them can be used in combination as required. You can also.

The reddish color of the dye precursor used in the heat-sensitive recording material of the present invention, 3, 3-bis (1-ethyl-2-methylindole-3-yl) phthalide, 3- (N-ethyl--N- p-tolyl) amino-7-methylfluorane is used, but in addition to these, 3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide, 3-diethylamino-7-chloro Fluorane and 3- (N-ethyl-N-isoamyl) amino-7-phenoxyfluorane can be used, and other red color-forming dye precursors as long as the desired effects of the present invention are not impaired. It is also possible to use 1 or more types together.

  Examples of red color-forming dye precursors include 3,3-bis (1-n-butyl-2-methylindole-3-yl) tetrachlorophthalide and 3,3-bis (1-n-butylindole- 3-yl) phthalide, 3,3-bis (1-n-pentyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-n-hexyl-2-methylindol-3-yl) Phthalide, 3,3-bis (1-n-octyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-methyl-2-methylindol-3-yl) phthalide, 3,3- Bis (1-propyl-2-methylindol-3-yl) phthalide, 3,3-bis (2-methylindol-3-yl) phthalide, rhodamine B-anilinolactam, rhodamine B- (o-chloroanilino) lacta Rhodamine B- (p-nitroanilino) lactam, 3-diethylamino-5-methyl-7-dibenzylaminofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6-methoxyfluorane 3-diethylamino-6-methylfluorane, 3-diethylamino-6-methyl-7-chloro-8-benzylfluorane, 3-diethylamino-6,7-dimethylfluorane, 3-diethylamino-6,8-dimethyl Fluorane, 3-diethylamino-7-methoxyfluorane, 3-diethylamino-7- (N-acetyl-N-methyl) aminofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7-methylethoxy Fluorane, 3-diethylamino-7-p-methylphenyl Luolan, 3-diethylamino-7,8-benzofluorane, 3-diethylaminobenzo [a] fluorane, 3-diethylaminobenzo [c] fluorane, 3-dimethylamino-7-methoxyfluorane, 3-dimethylamino-6- Methyl-7-chlorofluorane, 3-dimethylamino-7-methylfluorane, 3-dimethylamino-7-chlorofluorane, 3- (N-ethyl-p-toluidino) -7-methylfluorane, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-chlorofluorane, 3- (N-ethyl-N-isoamyl) amino-7,8-benzofluorane, 3- (N-ethyl-N -Isoamyl) amino-7-methylfluorane, 3- (N-ethyl-Nn-octyl) amino-6-methyl-7-chlorofluorane, 3- N-ethyl-Nn-octyl) amino-7,8-benzofluorane, 3- (N-ethyl-Nn-octyl) amino-7-methylfluorane, 3- (N-ethyl-N- n-octyl) amino-7-chlorofluorane, 3- (N-ethyl-N-4-methylphenyl) amino-7,8-benzofluorane, 3- (N-isopentyl-N-ethyl) amino-7 , 8-benzofluorane, 3- (N-ethoxyethyl-N-ethyl) amino-7,8-benzofluorane, 3- (N-ethoxyethyl-N-ethyl) amino-7-chlorofluorane, 3 -N-dibutylamino-6-methyl-7-chlorofluorane, 3-n-dibutylamino-7,8-benzofluorane, 3-n-dibutylamino-7-chlorofluorane, 3-n-dibutylamino -7-Me Tilfluorane, 3-diallylamino-7,8-benzofluorane, 3-diallylamino-7-chlorofluorane, 3-cyclohexylamino-6-chlorofluorane, 3-pyrrolidylamino-7-methylfluorane, 3 -Ethylamino-7-methylfluorane etc. are mentioned.

  In the heat-sensitive recording layer of the present invention, a dye precursor particle having a color tone other than red color developability in which a coating layer formed of an organic polymer is provided on the surface of the dye particle is included together with the red color developable dye precursor. Thus, it is possible to obtain a multicolor thermosensitive recording material that develops colors of two or more colors.

  In addition, the dye precursors of different color tones are contained in separate layers, and the dye precursor and the electron-accepting compound contained in the surface layer closer to the heating source are colored at a lower heating temperature. Although the dye precursor and the electron-accepting compound contained in the layer separated from the surface are colored at a higher heating temperature, it is possible to obtain a multicolor thermosensitive recording material that develops colors of two or more colors. In the present invention, there is a problem in that the color separation property is inferior, the layer configuration is complicated, and the productivity is lowered. A multicolor recording material containing dye precursor particles having a color tone other than the system color developability is preferred.

  As a method of providing a coating layer on the surface of the dye precursor particles in the present invention, a vinyl monomer is added to the dispersion of the dye precursor particles providing the coating layer, a polymerization initiator is added, and then heating is performed as necessary. The most preferable method is to form a coating layer by directly coating the surface of the dye precursor particles by addition polymerization. When the coating layer is formed by polymerizing a vinyl monomer, the productivity is better than when the coating layer is formed using a conventional microencapsulation method, and the properties of the coating layer can be freely controlled. Easy to do. The vinyl monomer is a compound that has at least one vinyl bond (carbon-carbon double bond) in the molecule and can undergo addition polymerization with the vinyl bond as an active point.

  The dispersion of the dye precursor particles provided with the coating layer can be obtained by a method of dry pulverizing the dye precursor and dispersing it in a dispersion medium, a method of mixing the dye precursor into the dispersion medium and wet pulverizing. Any method can be used as the method of pulverization.

  The average particle diameter of the dye precursor particles in the dispersion is usually 7 μm or less, preferably 0.1 to 5 μm, particularly preferably 0.1 to 2 μm. In the present invention, when the average particle diameter of the dye precursor particles is within this range, a coating layer can be efficiently provided, light scattering hardly occurs, the heat-sensitive recording layer has good transparency, and a colored image is obtained. Does not require much energy.

  Various states can be considered for the mixed state when the vinyl monomer is added to the dispersion of the dye precursor. That is, most of the dye precursor dispersion and the vinyl monomer are phase-separated to form separate phases, but a very small amount of the vinyl monomer is dissolved in the dye precursor dispersion. The dye precursor dispersion and the vinyl monomer are not completely dissolved and completely phase separated, and the vinyl monomer is mostly or completely dissolved in the dye precursor dispersion. State.

  Among these states, most of the dye precursor dispersion and the vinyl monomer are phase-separated to form separate phases, but a very small amount of vinyl monomer is in the dye precursor dispersion. When the vinyl monomer is polymerized in a state where the vinyl monomer is dispersed in the dye precursor dispersion and a very small amount is dissolved in the dye precursor dispersion, Compared with the case of polymerizing in this state, it is possible to form a coating layer that is more uniform and denser on the surface of the particles of the dye precursor and excellent in various properties.

  Most of the dye precursor dispersion and the vinyl monomer are phase-separated to form separate layers, but a very small amount of vinyl monomer is dissolved in the dye precursor dispersion. Can be realized by appropriately selecting the type of the dispersion medium in which the particles of the dye precursor are dispersed and the type of the vinyl monomer.

  In the present invention, an aqueous dispersion medium is preferably used as the dispersion medium for dispersing the dye precursor particles. The aqueous dispersion medium is water or a mixed solution of water and an organic solvent compatible with water. Specific examples of the organic solvent compatible with water include methyl alcohol, ethyl alcohol, isopropyl alcohol, Acetone, methyl ethyl ketone, ethylene glycol and the like can be mentioned, but there is no particular limitation as long as the organic solvent is compatible with water. When the dye precursor particles are dispersed in an aqueous dispersion medium, the dispersion stability of the dye precursor particles is good when the vinyl monomer is subjected to addition polymerization to form a coating layer on the surface of the dye precursor particles. Aggregation between dye precursor particles hardly occurs, and formation of a coating layer due to aggregation hardly occurs.

  Usually, a heat-sensitive recording material is prepared by applying a heat-sensitive recording component constituting a heat-sensitive recording layer to a support in the state of a coating liquid and drying it. From the viewpoint of productivity and safety, the coating material is applied. The main component of the liquid solvent / dispersion medium is often water. The fact that the dye precursor particles provided with the coating layer in the present invention are dispersed in the aqueous dispersion medium means that when a thermosensitive recording material containing the dye precursor particles is produced, a conventional thermosensitive recording material coating solution is used. The technology for producing the film can be applied as it is, which is advantageous from the viewpoint of industrial productivity.

  The vinyl monomer according to the present invention is composed of a compound having two or more vinyl bonds in addition to the compound having one vinyl bond, and by changing the content of the compound having two or more vinyl bonds, The characteristics of the coating layer can be freely changed. A coating layer formed by mixing and polymerizing a compound having one vinyl bond and a compound having two or more vinyl bonds is a compound having two or more vinyl bonds due to the crosslinked structure of the polymer forming the coating layer. Compared to a coating layer formed by polymerization without containing, the effect of improving the high-temperature heat-resistant storage stability and light-resistant storage stability is increased.

  The content of the compound having two or more vinyl bonds is preferably 1% by mass or more and 70% by mass or less, and more preferably 10% by mass or more and 50% by mass or less with respect to the total mass of the vinyl monomer. Within this range, the degree of freedom for quality design according to the purpose is increased while taking into consideration the balance between storage and thermal responsiveness.

  The addition amount of the vinyl monomer is preferably 0.5% by mass or more and 1000% by mass or less with respect to the dye precursor particles on which the coating layer is provided. Within this range, a coating having a sufficient function as a coating layer is possible, the polymerization proceeds easily, and aggregation does not easily occur at the time of polymerization, so that a heat-sensitive recording material having a sufficient color density can be obtained.

  Specific examples of the compound having only one vinyl bond used in the present invention include styrene, α-methylstyrene, α-methoxystyrene, m-bromostyrene, m-chlorostyrene, o-bromostyrene, o-chlorostyrene. P-bromostyrene, p-chlorostyrene, p-methylstyrene, p-methoxystyrene, 2-vinylpyridine, isobutene, 3-methyl-1-butene, butyl vinyl ether, methyl vinyl ketone, nitroethylene, vinylidene cyanide, Ethylene, propylene, vinyl chloride, vinyl acetate, acrolein, methylacrolein, acrylamide, N-methylolacrylamide, N, N-dimethylacrylamide, diacetoneacrylamide, N-octadecylacrylamide, α-acetoxyethyl acrylate, α- Ethyl loroacrylate, methyl α-chloroacrylate, methyl α-cyanoacrylate, methyl α-phenylacrylate, benzyl acrylate, butyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, acrylic Lauryl acid, tridecyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-methoxyethyl acrylate, 2-butoxyethyl acrylate, ethoxyethoxyethyl acrylate, methyl triglycol acrylate Cyclohexyl acrylate, tetrahydrofurfuryl acrylate, cyanoethyl acrylate, ferrocenylmethyl acrylate, glycidyl acrylate, heptafluorobutyl acrylate, methyl acrylate, octyl acrylate, Methyl trifluoroacrylate, 2-chloroethyl acrylate, 2-nitrobutyl acrylate, acrylic acid, α-bromoacrylic acid, 2-hydroxyethylacryloyl phosphate, acrylonitrile, allyl glycidyl ether, allyl acetic acid, allyl alcohol, allyl benzene N-allylstearylamide, 1-butene, 2-butene, N-vinylcaprolactam, ethyl N-vinylcarbamate, N-vinylcarbazole, crotonaldehyde, crotonic acid, 1,1-diphenylethylene, tetrafluoroethylene, fumarate Diethyl acid, 1-hexene, 1-vinylimidazole, 1-vinyl-2-methylimidazole, indene, diethyl maleate, maleic anhydride, maleimide, methacrylamide, benzyl methacrylate, Ethyl crylate, ferrocenyl methyl methacrylate, glycidyl methacrylate, isopropyl methacrylate, propyl methacrylate, methacrylic acid-n-butyl, methacrylic acid isobutyl, methacrylic acid-sec-butyl, methacrylic acid-tert-butyl, methacrylic acid 2-ethylhexyl, cyclohexyl methacrylate, isodecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, methyl methacrylate, phenyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, methacryl 2-Ethoxyethyl methacrylate, tetrahydrofurfuryl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, -3-chloro-2-hydroxy methacrylate Roxypropyl, methacrylic acid, methacryloxyethyl phosphate, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, N-methylolmethacrylamide, methacrylonitrile, methacryloylacetone, 2-isopropenyl-2-oxazoline, 2-vinylquinoline, benzoic acid Examples include, but are not limited to, vinyl acid, vinyl dodecyl ether, vinyl ethyl sulfoxide, vinyl formate, vinyl isobutyl ether, vinyl laurate, and vinyl phenyl ether. It can be used alone or in combination of two or more.

  Specific examples of the compound having two or more vinyl bonds include polyethylene glycol diacrylates such as ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, octaethylene glycol diacrylate, Polyethylene glycol dimethacrylates such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, 2,2-bis (4-acryloxyethoxyphenyl) propane, 2,2-bis (4 -Acryloxydiethoxyphenyl) propane, 2,2-bis (4-acryloxytriethoxyphenyl) propaprop 2,2-bis (4-acryloxypolyethoxyphenyl) propanes, 2,2-bis (4-methacryloxyethoxyphenyl) propane, 2,2-bis (4-methacryloxydiethoxyphenyl) propane, 2,2-bis (4-methacryloxypolyethoxyphenyl) propanes such as 2,2-bis (4-methacryloxytriethoxyphenyl) propane, allyl acrylate, 1,3-butanediol diacrylate, 1,4- Butanediol diacrylate, 1,5-pentanediol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, polypropylene glycol diacrylate, N, N'-methylenebisacrylamide, allyl methacrylate, 1,3- Butanedioldi Tacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, dipropylene glycol dimethacrylate, diallyl phthalate, diallyl chlorendate, butadiene, butadiene-1-carboxylate, diethyl butadiene-1,4-dicarboxylate , Diallyl melamine, diallyl phthalate, N, N-divinylaniline, divinyl ether, divinylbenzene, divinylnaphthalene, 1,3-butanediol dimethacrylate, isoprene, pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylolethanetri Methacrylate, trimethylolpropane trimethacrylate, triallyl cyanurate, triallyl isocyanurate, triallyl trimer Retate, tetramethylol methane tetraacrylate, tetramethylol methane tetramethacrylate and the like can be mentioned, but are not limited to these, and these compounds are used alone or in combination of two or more as required. can do.

  As the polymerization initiator to be added for addition polymerization of the vinyl monomer, known ones can be used, and the mode of the polymerization reaction is not particularly limited, such as radical polymerization, anionic polymerization, and cationic polymerization, but radical polymerization is particularly preferably used. It is done. In the polymerization, the system may be heated if necessary. Specific examples of the polymerization initiator for radical polymerization include hydrogen peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, dicumyl peroxide, di-tert-butyl peroxide, benzoyl peroxide, lauroyl peroxide, and the like. Oxides, persulfates such as potassium persulfate, ammonium persulfate, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis ( Azo compounds such as 4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2-methylpropionamidine) dihydrochloride, 4,4′-azobis (4-cyanovaleric acid), hydrogen peroxide And ferrous salt combination, persulfate and sodium acid sulfite combination, cumene hydroxyperoxide and ferrous salt Combinations, redox initiators such as a combination of benzoyl peroxide and diethylaniline, a combination of peroxide and metal alkyl, and a combination of oxygen and organometallic alkyl can be mentioned, but are not limited thereto, and These compounds can be used alone or in combination of two or more as required.

  The polymerization initiator for radical polymerization is not particularly limited as long as it generates an active radical by heat or light energy other than the above, but when the dye precursor particles are dispersed in an aqueous dispersion medium, Water-soluble polymerization initiators such as potassium persulfate, ammonium persulfate, and 2,2′-azobis (2-methylpropionamidine) dihydrochloride are particularly preferred.

  The amount of the polymerization initiator added is not particularly limited as long as the vinyl monomer starts addition polymerization, but in order to efficiently start addition polymerization, 0.001 mass relative to the vinyl monomer. % To 10% by mass is a preferred range.

  In the heat-sensitive recording material of the present invention, examples of the dye precursor provided with a coating layer formed from an organic polymer on the particle surface include those generally used for pressure-sensitive recording materials or heat-sensitive recording materials. However, it is not limited to these.

  A specific example is as follows. Examples of black dye precursors include 3-dibutylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-7- (2-chloroanilino) fluorane, 3-diethylamino-6-methyl-7-ani Linofluorane, 3-diethylamino-6-methyl-7- (3-methylphenylamino) fluorane, 3-diethylamino-6-methyl-7-xylidinofluorane, 3-diethylamino-7- (2-chloroanilino) fluorane 3-diethylamino-7- (3-trifluoromethylphenylamino) fluorane, 3-diethylamino-7- (2-carbomethoxy-phenylamino) fluorane, 3- (N-cyclohexyl-N-methyl) amino-6 Methyl-7-anilinofluorane, 3- (N-cyclopentyl-N-ethyl) amino- -Methyl-7-anilinofluorane, 3- (N-isoamyl-N-ethyl) amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-p-toluidino) -6-methyl- 7-anilinofluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7- (p-toluidino) fluorane, 3- (N-methyl-N-tetrahydrofurfuryl) amino-6-methyl -7-anilinofluorane, 3- (N-ethyl-N-tetrahydrofurfuryl) amino-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3 -Pyrrolidino-6-methyl-7-p-butylphenylaminofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3-dipentylamino-6-methyl-7-anilino Ruoran, and the like.

  Examples of green dye precursors include 3- (N-ethyl-Nn-hexyl) amino-7-anilinofluorane, 3- (N-ethyl-Np-tolyl) amino-7- (N -Phenyl-N-methyl) aminofluorane, 3- (N-ethyl-Nn-propyl) amino-7-dibenzylaminofluorane, 3- (N-ethyl-Nn-propyl) amino-6 -Chloro-7-dibenzylaminofluorane, 3- (N-ethyl-N-4-methylphenyl) amino-7- (N-methyl-N-phenyl) aminofluorane, 3- (N-ethyl-4) -Methylphenyl) amino-7-dibenzylaminofluorane, 3- (N-ethyl-4-methylphenyl) amino-6-methyl-7-dibenzylaminofluorane, 3- (N-ethyl-4-methyl) Phenyl) amino-6 Methyl-7- (N-methyl-benzyl) aminofluorane, 3- (N-methyl-Nn-hexyl) amino-7-anilinofluorane, 3- (N-propyl-Nn-hexyl) Amino-7-anilinofluorane, 3- (N-ethoxy-Nn-hexyl) amino-7-anilinofluorane, 3- (Nn-pentyl-N-allyl) amino-6-methyl- 7-anilinofluorane, 3- (Nn-pentyl-N-allyl) amino-7-anilinofluorane, 3-n-dibutylamino-6-chloro-7- (2-chloroanilino) fluorane, 3 -N-dibutylamino-6-methyl-7- (2-chloroanilino) fluorane, 3-n-dibutylamino-6-methyl-7- (2-fluoroanilino) fluorane, 3-n-dibutylamino-7- ( -Chloroanilino) fluorane, 3-n-dibutylamino-7- (2-chlorobenzylanilino) fluorane, 3,3-bis (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide, 3,6-bis ( Dimethylamino) fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide, 3-diethylamino-6-methyl-7-benzylamino-fluorane, 3-diethylamino-6-methyl-7-dibenzylaminofluoride Oran, 3-diethylamino-6-methyl-7-n-octylaminofluorane, 3-diethylamino-6-methyl-7- (N-cyclohexyl-N-benzylamino) fluorane, 3-diethylamino-6-methyl-7 -(2-Chloroanilino) fluorane, 3-diethylamino-6-methyl-7- (2- Trifluoromethylanilino) fluorane, 3-diethylamino-6-methyl-7- (3-trifluoromethylanilino) fluorane, 3-diethylamino-6-methyl-7- (2-ethoxyanilino) fluorane, 3- Diethylamino-6-methyl-7- (4-ethoxyanilino) fluorane, 3-diethylamino-6-chloro-7- (2-chloroanilino) fluorane, 3-diethylamino-6-chloro-7-dibenzylaminofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-diethylamino-6-ethylethoxy-7-anilinofluorane, 3-diethylamino-7-anilinofluorane, 3-diethylamino-7-methylani Linofluorane, 3-diethylamino-7-dibenzylaminofluorane, -Diethylamino-7-n-octylaminofluorane, 3-diethylamino-7-p-chloroanilinofluorane, 3-diethylamino-7-p-methylphenylanilinofluorane, 3-diethylamino-7- (N- (Cyclohexyl-N-benzylamino) fluorane, 3-diethylamino-7- (2-chloroanilino) fluorane, 3-diethylamino-7- (3-trifluoroanilino) fluorane, 3-diethylamino-7- (2-trifluoromethyl) Anilino) fluorane, 3-diethylamino-7- (2-ethoxyanilino) fluorane, 3-diethylamino-7- (4-ethoxyanilino) fluorane, 3-diethylamino-7- (2-chlorobenzylanilino) fluorane 3-dimethylamino-6-chloro-7-dive Ziraminofluorane, 3-dimethylamino-6-methyl-7-n-octylaminofluorane, 3-dimethylamino-7-dibenzylaminofluorane, 3-dimethylamino-7-n-octylaminofluorane, 3-dibutylamino-7- (2-fluoroanilino) fluorane, 3- [p- (p-anilinoanilino) anilino] -6-methyl-7-chlorofluorane, 3-anilino-7-dibenzylaminofluorane 3-anilino-6-methyl-7-dibenzylaminofluorane, 3-pyrrolidino-7-dibenzylaminofluorane, 3-pyrrolidino- (7-cyclohexylanilino) fluorane, 3-dibenzylamino-6- Methyl-7-dibenzylaminofluorane, 3-dibenzylamino-7-dibenzylaminofluorane, 3- Benzylamino-7- (2-chloroanilino) fluoran, and the like.

  Examples of blue electron-donating dye precursors include 3- (1-ethyl-2-methylindol-3-yl) -3- (4-diethylaminophenyl) phthalide and 3- (1-ethyl-2-methylindole) -3-yl) -3- (2-methyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4) -Aminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-methylaminophenyl) -4-azaphthalide, 3- (1 -Ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-ethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) ) -3- (2-Etoki -4-dimethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-dipropylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole- 3-yl) -3- (2-ethoxy-4-dibutylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4 -Dipentylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-dihexylaminophenyl) -4-azaphthalide, 3- ( 1 Ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-dihydroxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3 -(2-Ethoxy-4-dichloroaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-dibromoaminophenyl)- 4-Azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diallylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2- Methylindol-3-yl) -3- (2-ethoxy-4-dihydroxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- ( 2-Etoki Ci-4-dimethoxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethoxyaminophenyl) -4-azaphthalide 3- (1-Ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-dicyclohexylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindo- Ru-3-yl) -3- (2-ethoxy-4-dimethylethoxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2- Ethoxy-4-diethylethoxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylbutoxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-dimethylcyclohexylaminophenyl) -4-azaphthalide, 3- (1-ethyl) -2-Methylindol-3-yl) -3- (2-ethoxy-4-dimethoxycyclohexylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-Ethoxy-4-pyrrolidylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (3-ethoxy-4-diethylaminophenyl) ) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2,3-diethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1 Ethyl-2-methylindol-3-yl) -3- (4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2 -Chloro-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (3-chloro-4-diethylaminophenyl) -4-azaphthalide, 3 -(1-Ethyl-2-methylindole-3-yl) -3- (2-bromo-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3) -Yl) -3- (3-bromo-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethyl-4-diethylamino) Phenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-propyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2- Methylindol-3-yl) -3- (3-methyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2 -Nitro-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-allyl-4-diethylaminophenyl) -4-azaphthalide, 3 -(1-ethyl-2-methylindole-3-yl) -3- (2-hydroxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3) -Ile) 3- (2-Cyano-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-cyclohexylethoxy-4-diethylaminophenyl)- 4-Azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-methylethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2- Methylindol-3-yl) -3- (2-cyclohexylethyl-4-diethylaminophenyl) -4-azaphthalide, 3- (2-ethylindol-3-yl) -3- (2-ethoxy- 4-Diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-chloroindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-bromoindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2- Ethylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-propylindol-3-yl) -3- (2 -Ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methoxyindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3 -(1-Ethyl-2-ethoxyindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-phenylindole) -3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4) -Diethylaminophenyl) -7-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4,7-diazaphthalide, 3- ( 1-ethyl-4,5,6,7-tetrachloro-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl) -4-nitro-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-4-methoxy-2-methylindo-) Le-3 Yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-4-methylamino-2-methylindol-3-yl) -3- (2-ethoxy) -4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-4-methyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide 3- (2-Methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-chloro-2-methylindol-3-yl ) -3- (2-Ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-bromo-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylamino) Enyl) -4-azaphthalide, 3- (1-methyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-methyl- 2-Methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-propyl-2-methylindol-3-yl) -3- (2-Ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-butyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide 3- (1-butyl-2-indol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-pentyl-2-methylindole- 3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-hexyl-2-methylindol-3-yl) -3- (2-ethoxy-4-) Diethylaminophenyl) -4-azaphthalide, 3- (1-hexyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-octyl) -2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-octyl-2-methylindol-3-yl) -3 -(2-Ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-octyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminopheny ) -4,7-diazaphthalide, 3- (1-nonyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-methoxy) -2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethoxy-2-methylindol-3-yl) -3 -(2-Ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-phenyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4- Azaphthalide, 3- (1-pentyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-heptyl-2-methyl) Indol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-nonyl-2-methylindol-3-yl) -3- (2- Ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-dimethylamino-2-methylphenyl) -3- (4 -Dimethylaminophenyl) -6-dimethylaminophthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (4-diethylamino-2-n-hexyloxyphenyl) -4-azaphthalide, etc. Is mentioned. Moreover, it can be used individually or in mixture of 2 or more types as needed.

  The ratio of the electron-accepting compound represented by the general formula 1 of the present invention to the electron-donating dye precursor is preferably in the range of 0.5: 1 to 10: 1 by mass ratio. More preferably, it is the range of 1: 1 to 5: 1.

  The heat-sensitive recording material of the present invention can provide practically sufficient image storage stability, but if necessary, a hindered phenol compound, a hindered amine compound, a phosphate ester derivative, or a benzotriazole derivative may be added. Can do.

  Specific examples of hindered phenol compounds used in the heat-sensitive recording layer in the present invention as needed include 1,1,2,2-tetrakis (5-cyclohexyl-4-hydroxy-2-methylphenyl) ethane. 1,1,2,2-tetrakis (3-phenyl-4-hydroxyphenyl) ethane, 1,1,2,2-tetrakis (3-tert-butyl-4-hydroxyphenyl) ethane, 1,1,3 -Tris (3-cyclohexyl-4-hydroxyphenyl) butane, 1,1,3-tris (5-cyclohexyl-4-hydroxy-2-methylphenyl) butane, 1,1,3-tris (3-cyclohexyl-4 -Hydroxy-5-methylphenyl) butane, 1,1,3-tris (3-phenyl-4-hydroxyphenyl) butane, 1,1,3-tris ( 5-phenyl-4-hydroxy-2-methylphenyl) butane, 1,1,3-tris (3-tert-butyl-4-hydroxyphenyl) butane, 1,1,3-tris (5-tert-butyl- 4-hydroxy-2-methylphenyl) butane, 1,1,3,3-tetrakis (5-cyclohexyl-4-hydroxy-2-methylphenyl) propane, 1,1,3,3-tetrakis (3-cyclohexyl- 4-hydroxyphenyl) propane, 1,1,5,5-tetrakis (5-cyclohexyl-4-hydroxy-2-methylphenyl) pentane, 1,1,3,3-tetrakis (3-cyclohexyl-4-hydroxyphenyl) ) Pentane, 1,1,3,3-tetrakis (3-phenyl-4-hydroxyphenyl) propane, 1,1,3,3-tetrakis (5 Phenyl-4-hydroxy-2-methylphenyl) propane, 1,1,3,3-tetrakis (3-tert-butyl-4-hydroxyphenyl) propane, 1,1,3,3-tetrakis (5-tert- Butyl-4-hydroxy-2-methylphenyl) propane, 2,2-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol) ), 2,2'-ethylidenebis (4,6-di-tert-butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), 4,4'-thiobis ( 2-methyl-6-tert-butylphenol), 4,4'-thiobis (2-methylphenol), 4,4'-thiobis (2,6-dimethylphenol), 4,4'-thiobis (2,6-di-tert Butylphenol), 2,2'-thiobis (4-tert-octylphenol), 2,2'-thiobis (3-tert-octylphenol), 4,4'-butylidenebis (6-tert- Butyl-m-cresol), 1- [α-methyl-α- (4′-hydroxyphenyl) ethyl] 4- [α ′, α′-bis (4 ″ -hydroxyphenyl) ethyl] benzene, 2, Examples include 2-bis (4-hydroxy-3,5-dibromophenyl) propane and 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, but are not limited thereto. However, these compounds can be used alone or in combination of two or more as required.

  Specific examples of the hindered amine compound used in the heat-sensitive recording layer in the present invention as needed include bis (2,2,6,6, -tetramethyl-4-piperidyl) sebacate and succinic acid-bis (2 , 2,6,6, -tetramethyl-4-piperidyl) ester, butane-1,2,3,4-tetracarboxylic acid-tetrakis [1,2,2,6,6-pentamethyl (4-piperidyl)] Ester, butane-1,2,3,4-tetracarboxylic acid-tetrakis [2,2,6,6-tetramethyl (4-piperidyl)] ester, and the like. In addition, these compounds can be used alone or in combination of two or more as required.

  Specific examples of the phosphoric acid ester derivative used as necessary for the heat-sensitive recording layer in the present invention include triphenyl phosphate, diphenyl phosphate, bis (4-tert-butylphenyl) phosphate, bis (4,6-di-). -Tert-butylphenyl) phosphate, bis (4-chlorophenyl) phosphate, bis (benzyloxyphenyl) phosphate, 2,2'-methylenebis (4,6-di-tert-butylphenyl) phosphate, dimethyloxyphosphate, diethyloxy Phosphate, bis (3,5-di-tert-butyl-4-hydroxyphenyl) phosphate, 3,5-di-tert-butyldiphenyl phosphate, diethyl (3,5-di-tert-butyl-4-hydroxyphenyl) Phosphate, and 2,2'-methylenebis (4 6-di-tert-butylphenyl) phosphate sodium salt, 2,2'-methylenebis (4,6-di-tert-butylphenyl) phosphate calcium salt, 2,2'-methylenebis (4,6-di-) tert-butylphenyl) phosphate zinc salt, 2,2'-methylenebis (4,6-di-tert-butylphenyl) phosphate ammonium salt, potassium salt, and the like. However, these compounds can be used alone or in combination of two or more as required.

  Specific examples of the benzotriazole derivatives used as necessary for the heat-sensitive recording layer in the present invention include 2- (2-hydroxyphenyl) benzotriazole, 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-5-tert-butylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-tert-butylphenyl) benzotriazole, 2- (2-hydroxy-3-tert-butyl) -5-methylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3,5-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3,5-di -Tert-aminophenyl) benzotriazole, 2- (2-hydroxy-3,5-di-tert-butylphenyl) -5-tert-butyl Tylbenzotriazole, 2- (2-hydroxy-3-dodecyl-5-methylphenyl) benzotriazole, 2- [2-hydroxy-4- (2-ethylhexyl) oxyphenyl] benzotriazole, methyl-3- (3- Condensate with tert-butyl-5-benzotriazolyl-4-hydroxyphenyl) propionate-polyethylene glycol (molecular weight about 300), 5-tert-butyl-3- (5-chloro-benzotriazolyl) -4 -Hydroxybenzene-octyl propionate, 2- (2-hydroxy-3-sec-butyl-5-tert-butylphenyl) -5-tert-butylbenzotriazole, 2- (2-hydroxy-4-methoxy-5- Sulfophenyl) benzotriazole sodium salt, 2- (2-hydroxy-4-butoxy-5-sulfo Phenyl) benzotriazole sodium salt, 2,2'-methylenebis (4-methyl-6-benzotriazolylphenol), 2,2'-methylenebis [4-methyl-6- (5-methylbenzotriazolyl) phenol ], 2,2'-methylenebis [4-methyl-6- (5-chlorobenzotriazolyl) phenol], 2,2'-methylenebis [4- (1,1,3,3-tetramethylbutyl)- 6-benzotriazolylphenol], 2,2'-methylenebis (4-tert-butyl-6-benzotriazolylphenol), 2,2'-propylidenebis (4-methyl-6-benzotriazolylphenol) 2,2'-isopropylidenebis (4-methyl-6-benzotriazolylphenol), 2,2'-isopropylidenebis [4- (1,1 , 3,3-tetramethylbutyl) -6-benzotriazolylphenol], 2,2'-octylidenebis [4-methyl-6- (5-methylbenzotriazolyl) phenol], and the like. However, it is not limited thereto, and these compounds can be used alone or in combination of two or more as required.

  The amount of hindered phenol compound, hindered amine compound, phosphate ester derivative, or benzotriazole derivative used as necessary for the heat-sensitive recording layer in the present invention is a total amount, which is 1 for the electron-accepting compound. -15 mass% is a preferable range, and a more preferable range is 4-7 mass%. In this range, the thermal responsiveness, the saturated density of the colored image is good, the whiteness of the background portion is good, and the high-temperature heat-resistant storage stability improving effect of the colored image portion and the non-colored background portion is high. The heat-resistant storage stability of the part is also improved.

  The heat-sensitive recording layer constituting the heat-sensitive recording material of the present invention can contain a heat-fusible substance in order to improve its thermal response. In this case, those having a melting point of 60 ° C. to 180 ° C. are preferable, and those having a melting point of 80 ° C. to 140 ° C. are particularly preferably used.

  Specifically, stearic acid amide, N-hydroxymethyl stearic acid amide, N-stearyl stearic acid amide, ethylene bis stearic acid amide, N-stearyl urea, 1,2-bisphenoxyethane, 1,2-bis (3 -Methylphenoxy) ethane, benzyl-2-naphthyl ether, m-terphenyl, 4-benzylbiphenyl, 4-acetylbiphenyl 2,2'-bis (4-methoxyphenoxy) diethyl ether, α, α'-diphenoxyxylene 1,2-diphenoxyethane, 1,2-di (3-methylphenoxy) ethane, bis (4-methoxyphenyl) ether, diphenyl adipate, dibenzyl oxalate, di (4-methylbenzyl) oxalate, Acid di (4-chlorobenzyl) ester, dimethyl terephthalate, te Known heat-fusible substances such as dibenzyl phthalate, benzenesulfonic acid phenyl ester, bis (4-allyloxyphenyl) sulfone, 4-acetylacetophenone, acetoacetic anilides, fatty acid anilides and the like can be mentioned. These compounds can be used alone or in combination of two or more. Further, in order to obtain sufficient thermal responsiveness, it is preferable that the heat fusible substance occupies 5 to 50% by mass in the total solid content of the thermosensitive recording layer.

  The heat-sensitive recording layer constituting the heat-sensitive recording material of the present invention can be obtained by mixing each dispersion obtained by finely pulverizing each color forming component and a binder, and coating and drying on a support. The heat-sensitive recording layer may have a single layer structure or multiple layers.

  As the binder used in the heat-sensitive recording layer, various binders used in ordinary coating can be used.

  Specifically, starches, hydroxymethylcellulose, methylcellulose, ethylcellulose, carboxymethylcellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, sodium alginate, polyvinylpyrrolidone, polyacrylamide, acrylamide / acrylic acid ester copolymer, acrylamide / acrylic Acid ester / methacrylic acid terpolymer, alkali salt of polyacrylic acid, alkali salt of polymaleic acid, alkali salt of styrene / maleic anhydride copolymer, alkali salt of ethylene / maleic anhydride copolymer, isobutylene / Water-soluble binder such as alkali salt of maleic anhydride copolymer, and styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene Copolymer, acrylonitrile / butadiene / styrene terpolymer, polyvinyl acetate, vinyl acetate / acrylate copolymer, ethylene / vinyl acetate copolymer, polyacrylate, styrene / acrylate copolymer Examples thereof include water-dispersible binders such as coalescence and polyurethane, but are not limited thereto.

  For the heat-sensitive recording layer, diatomaceous earth, talc, kaolin, calcined kaolin, heavy calcium carbonate, precipitated calcium carbonate, magnesium carbonate, zinc oxide, aluminum oxide, aluminum hydroxide, magnesium hydroxide, titanium dioxide, barium sulfate are used as pigments. Inorganic pigments such as zinc sulfate, amorphous silica, amorphous calcium silicate, colloidal silica, and organic pigments such as melamine resin filler, urea-formalin resin filler, polyethylene powder, and nylon powder can be used.

  In addition, the heat-sensitive recording layer has a higher fatty acid metal salt such as zinc stearate and calcium stearate, a higher fatty acid amide such as stearic acid amide, paraffin, polyethylene wax, polyethylene oxide for the purpose of preventing thermal print head wear and sticking. Further, surfactants including anionic and nonionic high molecular weight materials, as well as fluorescent dyes, antifoaming agents, and the like are added as necessary as lubricants such as castor wax and dispersing / wetting agents.

  The method for forming the heat-sensitive recording layer is not particularly limited, and can be formed according to a conventionally known technique. Specific examples include various printing methods such as letterpress, lithographic, flexo, and gravure, air knife coating, rod blade coating, bar coating, blade coating, gravure coating, curtain coating, and E-bar coating. The heat-sensitive recording layer can be formed by coating the coating liquid on the support by a method such as coating and drying.

The solid coating amount of the heat-sensitive recording layer is usually 0.1 to 2.0 g / m ^{2 as} the solid coating amount of the dye precursor. By setting it within this range, the recorded image and thermal response are excellent, and the cost is advantageous.

In the heat-sensitive recording material of the present invention, if necessary, one or more undercoat layers containing a single layer or a plurality of layers of pigments or resins can be provided between the support and the heat-sensitive recording layer. When the heat-sensitive recording material of the present invention is provided with a subbing layer, the solid coating amount of the undercoat layer is preferably ^{1~30g / m 2, 3~20g / m} 2 is more preferable.

  In general, calcined kaolin is used as a pigment for the undercoat layer. In addition, diatomaceous earth, talc, kaolin, heavy calcium carbonate, precipitated calcium carbonate, magnesium carbonate, zinc oxide, aluminum oxide, aluminum hydroxide, Organic pigments such as magnesium hydroxide, titanium dioxide, barium sulfate, zinc sulfate, amorphous silica, amorphous calcium silicate, colloidal silica, organic pigments such as melamine resin filler, urea-formalin resin filler, polyethylene powder, nylon powder Pigments can be used.

  As the resin for the undercoat layer, various water-soluble resins or water-dispersible resins used in ordinary coating can be used. For example, starches, hydroxymethylcellulose, methylcellulose, ethylcellulose, carboxymethylcellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, sodium alginate, polyvinylpyrrolidone, polyacrylamide, acrylamide / acrylate ester copolymer, acrylamide / acrylate ester / Methacrylic acid terpolymer, alkali salt of polyacrylic acid, alkali salt of polymaleic acid, alkali salt of styrene / maleic anhydride copolymer, alkali salt of ethylene / maleic anhydride copolymer, isobutylene / maleic anhydride Water-soluble resin such as alkali salt of copolymer, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer , Acrylonitrile / butadiene / styrene terpolymer, polyvinyl acetate, vinyl acetate / acrylic acid ester copolymer, ethylene / vinyl acetate copolymer, polyacrylic acid ester, styrene / acrylic acid ester copolymer, polyurethane, etc. And water dispersible resin.

In the heat-sensitive recording material of the present invention, a protective layer can be formed on the heat-sensitive recording layer in order to further improve the chemical resistance of the image or to improve the recording running property as necessary. Such a protective layer is mainly composed of a water-soluble resin having a film-forming property or a water-dispersible resin, and is added to the ultraviolet absorber and the heat-sensitive recording layer as necessary while the adhesive is dissolved or dispersed. auxiliaries protective layer coating solution prepared by adding such to obtain the heat-sensitive recording layer, the coating amount after drying 0.2 to 10 g / m ^2, more preferably 0.5 to 5 g / m ² approximately It is formed by coating and drying so that

  The water-soluble resin or water-dispersible resin for the protective layer is appropriately selected from conventionally known water-soluble polymers or water-dispersible resins. That is, examples of the water-soluble resin include polyvinyl alcohol, modified polyvinyl alcohol, starch or derivatives thereof, cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, polyvinyl pyrrolidone, polyacrylamide, acrylamide / acrylic acid ester copolymer. , Acrylamide / acrylic acid ester / methacrylic acid terpolymer, alkali salt of polyacrylic acid, alkali salt of polymaleic acid, alkali salt of styrene / maleic anhydride copolymer, alkali salt of ethylene / maleic anhydride copolymer An alkali salt of an isobutylene / maleic anhydride copolymer, sodium alginate, gelatin, casein, an acid neutralized product of chitosan, and the like can be used.

  Examples of water-dispersible resins include styrene / butadiene copolymers, acrylonitrile / butadiene copolymers, methyl acrylate / butadiene copolymers, acrylonitrile / butadiene / styrene terpolymers, polyvinyl acetate, vinyl acetate / An acrylic ester copolymer, an ethylene / vinyl acetate copolymer, a polyacrylic ester, a styrene / acrylic ester copolymer, polyurethane and the like can be used.

  Among these, carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, epoxy-modified polyvinyl alcohol, and diacetone-modified polyvinyl alcohol are preferably used as the protective layer resin because a strong film can be formed.

  The protective layer can contain a pigment for the purpose of improving the recording running property, writing property, and the like. Specific examples of pigments include diatomaceous earth, talc, kaolin, calcined kaolin, heavy calcium carbonate, precipitated calcium carbonate, magnesium carbonate, zinc oxide, aluminum oxide, aluminum hydroxide, magnesium hydroxide, titanium dioxide, barium sulfate, sulfuric acid Inorganic pigments such as zinc, amorphous silica, amorphous calcium silicate, and colloidal silica, and organic pigments such as melamine resin filler, urea-formalin resin filler, polyethylene powder, and nylon powder can be used.

  In addition, the protective layer has higher fatty acid metal salts such as zinc stearate and calcium stearate, higher fatty acid amides such as stearic acid amide, paraffin, polyethylene wax for the purpose of improving recording running properties such as heat print head wear prevention and sticking prevention. Further, lubricants such as polyethylene oxide and castor wax are added as necessary.

  The formation method of the undercoat layer and the protective layer is not particularly limited, and can be formed according to a conventionally known technique. Specific examples include various printing methods, air knife coating, rod blade coating, bar coating, blade coating, gravure coating, curtain coating, E-bar coating, and other methods. And can be formed by drying.

  In the thermosensitive recording material of the present invention, an optional information recording layer such as a protective layer (barrier), an adhesive layer, a magnetic recording layer, an ink jet recording layer, etc. Or a smoothing process such as super calendering can be applied after each layer is applied.

Reference example 1
The thermosensitive recording material used in Reference Example 1 was prepared as described below, and the characteristics were evaluated.

<Preparation of dispersion A>
200 g of 3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide is dispersed in a mixture of 200 g of a 10% by weight sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water, and the average particle size is measured by a bead mill. Dispersion A was obtained by pulverizing to 0.9 μm.

<Preparation of dispersion B>
N- (2-hydroxyphenyl) -2-[(4-hydroxyphenyl) thio] acetamide (100 g) and N- (4-hydroxyphenyl) -2-[(4-hydroxyphenyl) thio] acetamide (100 g) A dispersion B was obtained by dispersing in a mixture of 200 g of a base-modified polyvinyl alcohol aqueous solution and 600 g of water and pulverizing with a bead mill until the average particle size became 0.9 μm.

<Preparation of dispersion C>
Dispersion C was obtained by dispersing 200 g of benzyl-2-naphthyl ether in a mixture of 200 g of a 10% by weight sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water, and pulverizing with a bead mill until the average particle size became 0.9 μm.

<Preparation of dispersion D>
200 g of calcium carbonate was dispersed in 800 g of an aqueous 0.5 mass% polyacrylic acid sodium salt solution, and stirred for 10 minutes with a homomixer to obtain dispersion D.

<Preparation of thermal recording layer coating solution A>
30 parts by weight of the above dispersion A, 70 parts by weight of dispersion B, 70 parts by weight of dispersion C, 80 parts by weight of dispersion D, 10 parts by weight of 40% by weight zinc stearate dispersion, 80 parts by weight of a completely saponified polyvinyl alcohol aqueous solution of 10% by weight Then, water was added so that the concentration of the heat-sensitive coating solution was 16% by mass, and the mixture was sufficiently stirred to prepare a coating solution A for heat-sensitive recording layer.

<Preparation of heat-sensitive coated paper>
An undercoat layer-forming coating solution consisting of 100 parts by weight of calcined kaolin, 24 parts by weight of 50% by weight styrene butadiene latex and 200 parts by weight of water is applied to a fine paper having a basis weight of 50 g / m ^{2 as} a solid content coating amount of 10 g / It was coated and dried to m ² to produce a heat-sensitive coated paper.

<Preparation of thermal recording material>
On the heat-sensitive coated paper, the heat-sensitive recording layer coating liquid A was applied and dried so that the solid content coating amount was about 5 g / m ² to prepare a heat-sensitive recording material.

  The produced heat-sensitive recording material was subjected to calendar treatment so that the Beck smoothness of the heat-sensitive recording layer coating surface was 300 to 800 seconds, and then subjected to the following evaluation.

[Print test]
Printing was performed using a facsimile testing machine TH-PMD manufactured by Okura Electric. A thermal head having a dot density of 8 dots / mm and a head resistance of 1685Ω was used, and an image was obtained by energizing with a head voltage of 21 V and a pulse width of 1.2 msec. The image and the unprinted background were measured with a Macbeth RD-918 reflection densitometer (magenta mode) to obtain an unprocessed image and a background density. The evaluation results are shown in Table 1.

[Light resistance test]
The image obtained in the printing test and the unprinted background were irradiated with a fluorescent lamp with an illuminance of 5000 lx for 100 hours, and then measured with a Macbeth RD-918 reflection density meter (magenta mode). The larger the numerical value of the image, the better the light-resistant image storage stability, and the lower the numerical value, the smaller the light-resistant background fogging and the better the light-resistant background preservation property. The evaluation results are shown in Table 1.

[Light recurrent color resistance test]
The thermal recording surface of the produced thermal recording material was irradiated with fluorescent lamp light having an illuminance of 5000 lx for 100 hours, and then printed in the same manner as in the printing test. The density of the obtained image was measured using a Macbeth RD-918 reflection densitometer (magenta Mode). The evaluation results are shown in Table 1.

Example 1
<Preparation of dispersion E>
200 g of 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide was dispersed in a mixture of 200 g of a 10% by weight sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water, and the average particle size was reduced to 0. 0 by a bead mill. Dispersion E was obtained by grinding to 9 μm.

A thermosensitive recording material was prepared in the same manner as in Reference Example 1 except that Dispersion A in Reference Example 1 was replaced with Dispersion E, and a printing test, a light resistance storage test, and a light resistance color reproduction test were performed. The evaluation results are shown in Table 1.

Example 2
<Preparation of dispersion F>
200 g of 3- (N-ethyl-Np-tolyl) amino-7-methylfluorane was dispersed in a mixture of 200 g of a 10% by weight sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water, and the average particle size was reduced to 0. 0 by a bead mill. Dispersion F was obtained by grinding to 9 μm.

A heat-sensitive recording material was prepared in the same manner as in Reference Example 1 except that the dispersion A in Reference Example 1 was replaced with the above-mentioned Dispersion F, and a printing test, a light-resistant storage stability test, and a light-recurring color resistance test were performed. The evaluation results are shown in Table 1.

Reference example 2
<Preparation of dispersion G>
200 g of 3- (N-ethyl-N-isoamyl) amino-7-phenoxyfluorane was dispersed in a mixture of 200 g of a 10% by weight sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water, and the average particle size was adjusted to 0.9 μm using a bead mill. The dispersion G was obtained by grinding until

A thermosensitive recording material was prepared in the same manner as in Reference Example 1 except that Dispersion A in Reference Example 1 was replaced with Dispersion G, and a printing test, a light-resistant storage stability test, and a light-recurring color resistance test were performed. The evaluation results are shown in Table 1.

Reference example 3
<Preparation of dispersion H>
Dispersion H was obtained by dispersing 200 g of 3-diethylamino-7-chlorofluorane in a mixture of 200 g of a 10% by weight sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water and pulverizing with a bead mill until the average particle size became 0.9 μm. It was.

A thermosensitive recording material was prepared in the same manner as in Reference Example 1 except that Dispersion A in Reference Example 1 was replaced with Dispersion H, and a printing test, a light fastness storage test, and a light recurring color fastness test were performed. The evaluation results are shown in Table 1.

Example 3
<Preparation of Dispersion I>
200 g of N- (2-hydroxyphenyl) -2-[(4-hydroxyphenyl) thio] acetamide was dispersed in a mixture of 200 g of a 10% by weight sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water, and the average particle size was 0 using a bead mill. Dispersion I was obtained by pulverization to 9 μm.

A thermosensitive recording material was prepared in the same manner as in Reference Example 1 except that Dispersion B in Reference Example 1 was replaced with Dispersion I, and a printing test, a light fastness storage test, and a light recurring color fastness test were performed. The evaluation results are shown in Table 1.

Reference example 4
<Preparation of Dispersion J>
3-Dibutylamino-6-methyl-7-anilinofluorane (5 g) was pulverized with 85 g of a 2.5% by weight aqueous polyvinyl alcohol solution with a ball mill to obtain a dye precursor dispersion having an average particle size of 1 μm. Next, this dispersion was transferred to a polymerization vessel, and 4 g of ethyl methacrylate and 1 g of ethylene glycol dimethacrylate were added and the temperature was raised to 70 ° C. while stirring. To this was added 5 g of a 1% by weight aqueous solution of potassium persulfate as a polymerization initiator, and the mixture was allowed to react for 6 hours while stirring was continued. Next, this was cooled to room temperature, and a dispersion J having a concentration of 12% by mass of electron donating dye precursor particles having a polymer coating layer provided on the surface was obtained.

<Preparation of thermal recording layer coating solution B>
50 parts by weight of the above dispersion J, 20 parts by weight of dispersion A prepared in Example 1, 70 parts by weight of dispersion B, 70 parts by weight of dispersion C, 80 parts by weight of dispersion D, 10 parts by weight of 40% by weight zinc stearate dispersion, 10 90 parts by mass of a mass% completely saponified polyvinyl alcohol aqueous solution was mixed, water was added so that the concentration of the thermal coating liquid was 16 mass%, and the mixture was sufficiently stirred to prepare a thermal recording layer coating liquid B.

<Preparation of thermal recording material>
On the heat-sensitive coated paper prepared in Reference Example 1, the heat-sensitive recording layer coating liquid B was applied and dried so that the solid content coating amount was about 8 g / m ² to prepare a heat-sensitive recording material. .

  The produced heat-sensitive recording material was subjected to calendar treatment so that the Beck smoothness of the heat-sensitive recording layer coating surface was 300 to 800 seconds, and then subjected to the following evaluation.

[Print test]
Printing was performed using a facsimile testing machine TH-PMD manufactured by Okura Electric. Using a thermal head with a dot density of 8 dots / mm and head resistance of 1685Ω, a red color image is obtained by energizing with a head voltage of 21 V and a pulse width of 1.0 msec, and a black color image with a pulse width of 1.7 msec. Got. With a Macbeth RD-918 reflection densitometer, the red color image and the unprinted background were measured in the magenta mode, and the black color image was measured in the black mode to obtain an unprocessed image and a background density. The evaluation results are shown in Table 1.

[Light resistance test]
After irradiating the image obtained in the printing test and the unprinted background with fluorescent light of 5000 lx for 100 hours, the Macbeth RD-918 reflection densitometer is used to display the red-colored image and the unprinted background in magenta mode. The black color image was measured in the black mode. The larger the numerical value of the image, the better the light-resistant image storage stability, and the lower the numerical value, the smaller the light-resistant background fogging and the better the light-resistant background preservation property. The evaluation results are shown in Table 1.

[Light recurrent color resistance test]
The heat-sensitive recording surface of the produced heat-sensitive recording material was irradiated with fluorescent light with an illuminance of 5000 lx for 100 hours, and then printed in the same manner as in the printing test. The density of the obtained image was measured with a Macbeth RD-918 reflection densitometer. The red color image was measured in the magenta mode, and the black color image was measured in the black mode. The evaluation results are shown in Table 1.

Example 4
In Reference Example 4 , except that Dispersion E was used instead of Dispersion A, a heat-sensitive recording material was prepared in the same manner as Reference Example 4, and a printing test, a light fastness test, and a light recurrence color resistance test were performed. . The evaluation results are shown in Table 1.

Example 5
In Reference Example 4 , a heat-sensitive recording material was prepared in the same manner as Reference Example 4 except that Dispersion F was used instead of Dispersion A, and a printing test, a light fastness storage test, and a light recurring color fastness test were performed. . The evaluation results are shown in Table 1.

Reference Example 5
In Reference Example 4 , except that Dispersion G was used instead of Dispersion A, a heat-sensitive recording material was prepared in the same manner as Reference Example 4, and a printing test, a light fastness test, and a light recurrence color resistance test were performed. . The evaluation results are shown in Table 1.

Reference Example 6
In Reference Example 4 , a heat-sensitive recording material was prepared in the same manner as in Reference Example 4 except that Dispersion H was used instead of Dispersion A, and a printing test, a light fastness storage test, and a light recurring color fastness test were performed. . The evaluation results are shown in Table 1.

Reference Example 7
In Reference Example 4 , a heat-sensitive recording material was prepared in the same manner as in Reference Example 4 except that Dispersion H was used instead of Dispersion A and Dispersion I was used instead of Dispersion B. Test and resistance to light recurrence were conducted. The evaluation results are shown in Table 1.

Reference Example 8
<Preparation of dispersion K>
Disperse by dispersing 200 g of 3-dibutylamino-6-methyl-7-anilinofluorane in a mixture of 200 g of a 10% by mass sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water, and pulverizing with a beer mill until the average particle size becomes 1 μm. Liquid K was obtained.

<Preparation of thermal recording layer coating liquid C>
30 parts by weight of the above dispersion K, 70 parts by weight of dispersion I, 70 parts by weight of dispersion C, 80 parts by weight of dispersion D, 10 parts by weight of 40% by weight zinc stearate dispersion, and 80 parts by weight of 10% by weight completely aqueous saponified polyvinyl alcohol solution Then, water was added so that the concentration of the heat-sensitive coating solution was 16% by mass, and the mixture was sufficiently stirred to prepare a heat-sensitive recording layer coating solution C.

<Preparation of thermal recording layer coating liquid D>
30 parts by weight of the above dispersion H, 70 parts by weight of dispersion I, 70 parts by weight of dispersion C, 80 parts by weight of dispersion D, 10 parts by weight of 40% by weight zinc stearate dispersion, 80 parts by weight of a completely saponified aqueous polyvinyl alcohol solution Then, water was added so that the concentration of the heat-sensitive coating solution was 16% by mass, and the mixture was sufficiently stirred to prepare a heat-sensitive recording layer coating solution D.

<Preparation of thermal recording material>
On the heat-sensitive coated paper prepared in Reference Example 1, the heat-sensitive recording layer coating solution C is applied and dried so that the solid content coating amount is about 2.5 g / m ² , and further the heat-sensitive recording is performed. The layer coating solution D was coated and dried so that the solid coating amount was about 2.5 g / m ² , thereby producing a heat-sensitive recording material.

  The produced heat-sensitive recording material was subjected to calendar treatment so that the Beck smoothness of the heat-sensitive recording layer coating surface was 300 to 800 seconds, and then subjected to the following evaluation.

[Print test]
Printing was performed using a facsimile testing machine TH-PMD manufactured by Okura Electric. Using a thermal head with a dot density of 8 dots / mm and head resistance of 1685Ω, a red color image is obtained by energizing with a head voltage of 21 V and a pulse width of 1.0 msec, and a black color image with a pulse width of 1.7 msec. Got. With a Macbeth RD-918 reflection densitometer, the red color image and the unprinted background were measured in the magenta mode, and the black color image was measured in the black mode to obtain an unprocessed image and a background density. The evaluation results are shown in Table 1.

[Light resistance test]
After irradiating the image obtained in the printing test and the unprinted background with fluorescent light of 5000 lx for 100 hours, the Macbeth RD-918 reflection densitometer is used to display the red-colored image and the unprinted background in magenta mode. The black color image was measured in the black mode. The larger the numerical value of the image, the better the light-resistant image storage stability, and the lower the numerical value, the smaller the light-resistant background fogging and the better the light-resistant background preservation property. The evaluation results are shown in Table 1.

[Light recurrent color resistance test]
The heat-sensitive recording surface of the produced heat-sensitive recording material was irradiated with fluorescent light with an illuminance of 5000 lx for 100 hours, and then printed in the same manner as in the printing test. The density of the obtained image was measured with a Macbeth RD-918 reflection densitometer. The red color image was measured in the magenta mode, and the black color image was measured in the black mode. The evaluation results are shown in Table 1.

(Comparative Example 1)
<Preparation of dispersion L>
Dispersion L was prepared by dispersing 200 g of 4-hydroxy-4'-isopropoxydiphenylsulfone in a mixture of 200 g of a 10% by weight sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water, and pulverizing with a bead mill until the average particle size became 0.9 μm. Got.

In Reference Example 3 , a heat-sensitive recording material was prepared in the same manner as Reference Example 1 except that the dispersion L was used instead of the dispersion B, and a printing test, a light fastness storage test, and a light recurrence color resistance test were performed. did. The evaluation results are shown in Table 1.

(Comparative Example 2)
<Preparation of dispersion M>
Dispersion M was obtained by dispersing 200 g of 3-diethylaminobenzo [a] fluorane in a mixture of 200 g of a 10% by weight sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water, and pulverizing with a bead mill until the average particle size became 0.9 μm. .

In Reference Example 1, a thermosensitive recording material was prepared in the same manner as in Reference Example 1 except that 30 parts by mass of the above dispersion M was used instead of 30 parts by mass of the dispersion A, and a printing test, a light fastness test, and a light fast recurrence color were produced. A sex test was performed. The evaluation results are shown in Table 1.

(Comparative Example 3)
In Example 5 , a heat-sensitive recording material was prepared in the same manner as in Reference Example 4 except that 70 parts by mass of the dispersion L used in Comparative Example 1 was used instead of 70 parts by mass of the dispersion B. A test and a light recurrent color resistance test were conducted. The evaluation results are shown in Table 1.

(Comparative Example 4)
<Preparation of dispersion N>
200 g of 3- (di-n-butyl) amino-6-methyl-7-bromofluorane was dispersed in a mixture of 200 g of a 10% by weight sulfone group-modified polyvinyl alcohol aqueous solution and 600 g of water, and the average particle size was reduced to 0. 0 by a bead mill. A dispersion liquid N was obtained by grinding to 9 μm.

In Reference Example 4 , a heat-sensitive recording material was prepared in the same manner as in Reference Example 4 except that 20 parts by weight of the above dispersion N was used instead of 20 parts by weight of dispersion A, and a printing test, a light fastness test, and a light fast recurrence color were obtained. A sex test was performed. The evaluation results are shown in Table 1.

As is clear from Table 1, Examples 1 to 5 and Reference Examples 1 to 8 are superior to Comparative Examples 1 to 4 in light-resistant storage stability and light-recurring color resistance of red-colored images. It also contains both N- (2-hydroxyphenyl) -2-[(4-hydroxyphenyl) thio] acetamide and N- (4-hydroxyphenyl) -2-[(4-hydroxyphenyl) thio] acetamide. Examples 1 , 2, 4, 5 and Reference Examples 1 to 6 are superior in storage stability to Examples 3 and 7 and 8 . Further, among them, Examples 1 and 4 and Reference Examples 1 and 4 are particularly excellent in light-resistant storage stability and light-recurring color resistance.

However, in Reference Example 8 which is a multi-color heat-sensitive recording material of a heat-sensitive recording layer laminate type, heat-sensitive recording using a dye precursor in which a coating layer is provided on the surface of the dye particle as in Examples 4 and 5 and Reference Examples 4 to 7 . Compared with single-layer multicolor thermosensitive recording materials, the degree of black color mixture in unprocessed and red images after storability tests is large, and the color separation between red and black colors is inferior. When used as a recording material, Examples 4, 5 and Reference Examples 4 to 7 are more excellent.

Claims (1)

A heat-sensitive recording material comprising a support and a heat-sensitive recording material comprising an electron-accepting compound that reacts with an electron-donating usually colorless or light-colored dye precursor upon heating to develop a color of the dye precursor. N- (2-hydroxyphenyl) -2-[(4-hydroxyphenyl) thio] acetamide and N- (4-hydroxyphenyl) -2-[(4-hydroxyphenyl) are used as at least electron-accepting compounds in the recording layer. ) thio] contains at least one selected from acetamide, as an electron donating reddish coloring dye precursor, 3, 3-bis (1-ethyl-2-methylindole-3-yl) phthalide及 beauty A heat-sensitive recording material comprising at least one selected from 3- (N-ethyl-Np-tolyl) amino-7-methylfluorane.