JP5272622B2 - Multicolor thermal recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multicolor thermosensitive recording material which is excellent in sufficient color developing concentration, color separability, light stability for a long time, storage stability of a skin portion after heat and moisture resistance test, and plasticizer resistance of a printing portion and which uses the color developing reaction of a leuco dye and a coloring agent developing color tone close to the red color of a vermilion inkpad. <P>SOLUTION: The multicolor thermosensitive recording material constituted by arranging the first thermosensitive color developing layer containing a dye precursor and a developer developing color in black on a support body and arranging the second thermosensitive color developing layer containing a dye precursor and a developer developing color in a color tone different from the black on the first thermosensitive color developing layer contains 3,3-bis(1-butyl-2-methylindole-3-yl)phthalide and 3-diethylamino-7-chlorofluoran as the dye precursor in the second thermosensitive color developing layer and contains a specific ultraviolet absorber in the second thermosensitive color developing layer. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention provides sufficient color density and color separation, long-term light resistance, storage stability of the background after the heat and humidity test, good plasticizer resistance of the printed area, and color development close to the red color of vermilion The present invention relates to a multicolor thermosensitive recording material.

  A heat-sensitive recording material is known which utilizes a color reaction between a colorless or light leuco dye and an organic or inorganic developer to bring a coloring image into contact with both coloring substances by heat. Such heat-sensitive recording materials are relatively inexpensive, and since the recording equipment is compact and relatively easy to maintain, they are used not only as recording media for facsimiles and various printers but also in a wide range of fields.

  Colored images of such heat-sensitive recording materials are known to be black-colored, single-colored, such as red-colored, blue-colored, and green-colored, and multicolored heat-sensitive recording materials such as full-color and two-color-colored. Yes. Among the multi-color recording means, two-color color development, particularly red-black two-color heat-sensitive recording material, has been put to practical use, and has the advantage that characters and figures to be emphasized can be displayed clearly and distinctly with different color tones. . However, the red and black two-color heat-sensitive recording materials proposed so far are not necessarily satisfactory in terms of both color development sensitivity and color separation, and printing and blank paper storage (heat resistance, moisture resistance, light resistance). It wasn't. In particular, a heat-sensitive recording material that develops red in red as a red color tone is generally desired, but in the field of conventional heat-sensitive recording, a multi-color heat-sensitive recording material that exhibits these clear red in red There was no.

  Attempts have been made to utilize the difference in heating temperature or the difference in heat energy as a multicolor recording system, and various multicolor thermosensitive recording materials have been proposed. In general, a multicolor thermosensitive recording material is formed by sequentially laminating a high-temperature color-developing layer and a low-temperature color-developing layer that develop colors in different colors on a support. 2 and 3) and additive type (see Patent Documents 4, 5, 6, and 7) and a method using microcapsules (see Patent Documents 8, 9, 10, 11, and 12) are disclosed. ing. Moreover, the method (refer patent document 13, 14, 15) which uses the composite particle which consists of organic polymer and dye precursor by this applicant is also disclosed. Furthermore, the dye precursor is covered with a color control layer polymerized with a compound having an unsaturated carbon bond, and a specific red color developing dye and a specific electron accepting property which do not have a color control layer in the surface of the thermosensitive recording layer. A method of containing a developer is disclosed (see Patent Document 16). Furthermore, a method of containing a diphenylsulfone cross-linking compound as a developer for the high-temperature coloring layer of a multicolor thermosensitive recording material is also disclosed (see Patent Document 17).

Japanese Patent Laid-Open No. 50-17865 JP-A-57-14320 Japanese Patent Laid-Open No. 2-80287 Japanese Patent Publication No.49-27708 Japanese Patent Publication No.51-19989 Japanese Patent Laid-Open No. 51-146239 JP-A-56-99697 JP 57-12695 A Japanese Patent Publication No.49-70 JP 59-214691 A Japanese Patent Publication No. 4-4960 Japanese Patent Laid-Open No. 4-101885 JP-A-9-263057 Japanese Patent Laid-Open No. 10-226175 Japanese Patent Laid-Open No. 10-95173 JP 2006-281473 A JP 2001-162951 A

  It is necessary to add a large amount of decoloring agent to the decoloring type multicolor thermosensitive recording material in order to obtain a sufficient decoloring effect for the low temperature coloring layer. The recorded color image fades during long-term storage due to the action of the decolorant added in a large amount, or an extra amount of heat is required to melt the decolorant, which places an excessive burden on the thermal head, etc. There is a problem, and the image recording reliability and the recording sensitivity are not always satisfactory.

  Additive type multicolor thermosensitive recording materials include multi-layer structures in which a heat-sensitive color-developing layer in which a high-temperature color-developing layer and a low-temperature color-developing layer are sequentially laminated on a support are separated into separate layers, and materials that develop color at high or low temperatures. As a typical example, one having at least one single-layer structure separated by microcapsules or the like can be given. The multilayer structure is a method of obtaining two distinct colors by laminating two heat-sensitive color-developing layers that develop different colors and applying different amounts of heat. When the upper thermosensitive coloring layer develops color at low temperatures, and both the upper and lower thermosensitive coloring layers develop color, and a mixed color image of both colors is obtained. Is suitable. Since no color eraser is used in the color-added recording material, it has the advantage of being excellent in long-term storage of recorded images and being relatively inexpensive to manufacture, and requires extra heat to melt the color eraser. Therefore, there is an advantage that the high-temperature coloring layer can be colored with low energy as compared with the decoloring type. However, the additive type two-color heat-sensitive recording material has a problem that if the amount of heat is excessively applied during low-temperature color development, the high-temperature color-developing layer also partially develops color mixing, which makes it difficult for the low-temperature color-development image to become clear. In addition, a method of mixing two or more types of dye precursors having different color tone and different average particle diameter in the same color developing layer has been described, but there is also a problem that color mixing is unavoidable during low temperature color development. It was.

  Some heat-sensitive coloring layers have a single-layer structure that uses microcapsules to perform color separation for low-temperature and high-temperature printing. In these methods, dye precursors are separated from each other by a capsule wall film, so color separation is possible. However, the microcapsules contain an oily liquid in which a dye precursor is dissolved or emulsified, and the capsules are broken due to pressure and friction during handling, resulting in a background coloration.

  Furthermore, it is of a single layer structure, the dye precursor is covered with a color control layer polymerized with a compound having an unsaturated carbon bond, and a specific red color developability without a color control layer in the surface of the heat-sensitive recording layer In the method of containing two kinds of dyes and a specific electron-accepting developer, a red color tone close to vermilion is obtained, but because of the single layer structure, color separation is still insufficient or red dye 2 There is a drawback that background fogging occurs due to the melting point drop caused by the combined use of seeds.

  The object of the present invention is to provide sufficient color density and color separation, long-time light resistance, storage stability of the background after the heat and humidity test, excellent plasticizer resistance of the printed part, and close to red of vermilion The present invention provides a multicolor thermosensitive recording material that develops colors.

  As a result of various studies on the above problems, the present inventors provided a first thermosensitive color developing layer containing a black color developing dye precursor and a developer on the support, and further on the first thermosensitive color developing layer, In a multicolor thermosensitive recording medium provided with a second thermosensitive coloring layer containing a dye precursor and a developer that develops a color tone different from that of black color development, the color development is different from the black color development in the second thermosensitive coloring layer. 3,3-bis (1-butyl-2-methylindol-3-yl) phthalide and 3-diethylamino-7-chlorofluorane as dye precursors to be used, and in the second thermosensitive coloring layer It has been found that the above problems can be solved by containing benzotriazole, and the present invention has been completed.

  That is, the present invention provides the following multicolor thermosensitive recording material.

Item 1: A first heat-sensitive color developing layer containing a dye precursor that develops black color and a developer is provided on a support, and further a dye precursor that produces a color tone different from that of black color on the first heat-sensitive color developing layer. In the multicolor thermosensitive recording material provided with the second thermosensitive coloring layer containing the color developer and the developer, 3,3-bis (1-butyl-2-methyl) is used as the dye precursor in the second thermosensitive coloring layer. 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, which contains indol-3-yl) phthalide and 3-diethylamino-7-chlorofluorane as a UV absorber in the second thermosensitive coloring layer; At least selected from-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-5'-tert-octylphenyl) benzotriazole 1 type, and 2.5 parts by mass or more of 3-diethylamino-7-chlorofluorane with respect to 1 part by mass of the 3,3-bis (1-butyl-2-methylindol-3-yl) phthalide A multicolor thermosensitive recording material containing 5 parts by mass or less .
Item 2: The multicolor thermosensitive recording material according to Item 1, wherein the ultraviolet absorber is contained in an amount of 5 to 35% by mass based on the total solid content of the second thermosensitive coloring layer.
Item 3: The multicolor heat-sensitive recording material according to Item 1 or 2, wherein the melting point of the black dye-forming dye precursor of the first heat-sensitive color developing layer is 200 ° C or higher.
Item 4: Any one of Items 1 to 3 , wherein the black color developing dye precursor of the first thermosensitive coloring layer is 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane. The multicolor thermosensitive recording material according to Item.
Section 5: second thermosensitive coloring layer, either the total amount 100 parts by weight of the dye precursor which develops different color tones and black color, hydroxypropylmethylcellulose containing 10 to 30 parts by weight, of claim 1-4 The multicolor thermosensitive recording material according to claim 1.
Item 6: Any one of Items 1 to 5 , wherein the second thermosensitive coloring layer contains 5 to 70 parts by mass of a hindered amine compound with respect to 100 parts by mass of the total amount of the dye precursor that develops a color tone different from that of black. The multicolor thermosensitive recording material according to claim 1.
Item 7: The multicolor thermosensitive recording material according to any one of Items 1 to 6 , wherein the first thermosensitive coloring layer contains spherical plastic resin particles and / or hollow plastic resin particles.
Item 8: The multicolor thermosensitive recording material according to any one of Items 1 to 7 , wherein the first thermosensitive coloring layer contains at least one diphenylsulfone cross-linking compound represented by the following general formula (1).

（但し、ｎは１〜７の整数を表わす）
項９：第１感熱発色層及び第２感熱発色層のそれぞれの主たる顕色剤が同一の化合物であり、前記顕色剤が、Ｎ−ｐ−トルエンスルホニル−Ｎ’−３−（ｐ−トルエンスルホニルオキシ）フェニルウレア、４−ヒドロキシ−４’−イソプロポキシジフェニルスルホン、３，３’−ジアリル−４，４’−ジヒドロキシジフェニルスルホン、及び４−ヒドロキシ−４’−アリルオキシジフェニルスルホンから選ばれる少なくとも一種である、項１〜８のいずれか一項に記載の多色感熱記録材料。
項１０：第２感熱発色層に、更にポリウレア及びポリウレアーポリウレタンより選ばれる少なくとも１種以上の有機高分子と、黒発色する染料前駆体とからなる複合粒子を含有する、項１〜９のいずれか一項に記載の多色感熱記録材料。
項１１：第１感熱発色層及び第２感熱発色層が、それぞれカーテン塗布法により塗布形成されることを特徴とする、項１〜１０のいずれか一項に記載の多色感熱記録材料。
項１２：第１感熱発色層及び第２感熱発色層が、同時多層カーテン塗布法により塗布形成されることを特徴とする、項１〜１１のいずれか一項に記載の多色感熱記録材料。

(Where n represents an integer of 1 to 7)
Item 9: The main color developers of the first thermosensitive color developing layer and the second heat sensitive color developing layer are the same compound, and the color developer is Np-toluenesulfonyl-N′-3- (p-toluene). Sulfonyloxy) phenylurea, 4-hydroxy-4′-isopropoxydiphenylsulfone, 3,3′-diallyl-4,4′-dihydroxydiphenylsulfone, and 4-hydroxy-4′-allyloxydiphenylsulfone Item 9. The multicolor thermosensitive recording material according to any one of Items 1 to 8 , which is a kind.
Item 10: The compound according to any one of Items 1 to 9 , wherein the second thermosensitive coloring layer further comprises composite particles comprising at least one organic polymer selected from polyurea and polyurea polyurethane and a dye precursor that develops black color. The multicolor thermosensitive recording material according to claim 1.
Item 11: The multicolor thermosensitive recording material according to any one of Items 1 to 10 , wherein the first thermosensitive coloring layer and the second thermosensitive coloring layer are each formed by coating by a curtain coating method.
Item 12: The multicolor thermosensitive recording material according to any one of Items 1 to 11 , wherein the first thermosensitive coloring layer and the second thermosensitive coloring layer are formed by coating by a simultaneous multilayer curtain coating method.

  According to the present invention, the color sensitivity and color separation property, and the multicolor thermosensitive color which is excellent in the storage stability of the printed part and the background part after long-time light resistance, heat resistance and humidity resistance test, and develops a red color close to red of vermilion. Recording materials can be provided.

  Hereinafter, the multicolor thermosensitive recording material according to the present invention will be described in detail. In the present invention, a first thermosensitive coloring layer containing a black color developing dye precursor and a developer is provided on a support, and further a dye that develops a color tone different from black coloring on the first thermosensitive coloring layer. In a multicolor thermosensitive recording medium provided with a second thermosensitive coloring layer containing a precursor and a developer, 3,3-, as a dye precursor that develops a color tone different from the black coloring in the second thermosensitive coloring layer A thermosensitive recording layer containing bis (1-butyl-2-methylindol-3-yl) phthalide and 3-diethylamino-7-chlorofluorane, and further containing a specific benzotriazole in the second thermosensitive coloring layer; It is formed on a support.

  In the present invention, various known dye precursors for black coloring of the first thermosensitive coloring layer can be used, but those having a melting point of 200 ° C. or higher are particularly preferred from the viewpoint of color separation. For example, 3- (N-ethyl-p-toluidino) -6-methyl-anilinofluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7- (p-toluidino) fluorane, 3- Piperidino-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-diethylamino-7- (o- Fluoroanilino) fluorane, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluorane), 3- (4-dimethylamino) alinino-5,7-dimethylfluorane, etc. Although mentioned, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane is more preferable because it is excellent in light resistance. The dye precursor used in the present invention is not limited to these, and two or more kinds may be used in combination. If necessary, blue, green, yellow, and red dye precursors may be added in addition to the black color as long as the effects of the present invention are not impaired. The amount of the dye precursor used is about 3 to 30% by mass with respect to the total solid content of the heat-sensitive recording layer.

  In addition, by including spherical plastic resin particles or hollow plastic resin particles in the first thermosensitive coloring layer, the contrast between black coloring and a color that develops in a color different from black is improved, and the color tone differs from black. It has become possible to greatly improve the storage stability of the color to be developed, especially the chemical resistance against plasticizers and oils. Such plastic resin particles are resin particles mainly composed of polystyrene, and the main monomer is styrene, aromatic vinyl compounds such as α-methylstyrene and vinyltoluene, methyl acrylate, ethyl acrylate, acrylic acid. Resin particles using acrylic acid esters such as butyl, vinyl esters such as vinyl acetate and vinyl propionate, vinylcyan compounds such as acrylonitrile, and vinyl halide compounds such as vinyl chloride and vinylidene chloride. The particle size is preferably about 0.2 to 3.0 μm in terms of sensitivity and image quality. The content of the plastic particles used in the present invention is about 5 to 30% by mass, preferably about 10 to 20% by mass, based on the total solid content of the first thermosensitive coloring layer. It is poor, and if it exceeds 30% by mass, the coloring ability is lowered, which is not preferable.

  In the present invention, in order to improve image stability, it is desirable that the first thermosensitive coloring layer contains at least one diphenylsulfone cross-linking compound represented by the following general formula (1).

（但し、ｎは1〜7の整数を表わす）

(However, n represents an integer of 1 to 7)

  The total amount of the diphenylsulfone cross-linking compound used in the first thermosensitive coloring layer is not particularly limited, but is 100 to 1000 parts by weight, preferably 100 to 500 parts by weight, based on 100 parts by weight of the total dye precursor. Part is preferred. By containing the diphenylsulfone cross-linking compound in the first thermosensitive coloring layer, the chemical resistance of the black coloring portion and the coloring portion derived from the solid dye fine particles that develop a color tone different from the black coloring in the second thermosensitive coloring layer. Can be improved.

  In the present invention, various known compounds can be used as the developer used in the first heat-sensitive recording layer and the second heat-sensitive recording layer. Specific examples of the developer include 4-tert-butylphenol, 4-acetylphenol, 4-tert-octylphenol, 4,4′-sec-butylidenediphenol, 4-phenylphenol, 4,4′- Dihydroxydiphenylmethane, 4,4′-isopropylidene diphenol, 4,4′-cyclohexylidene diphenol, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 4,4′-dihydroxydiphenyl sulfide, 4 , 4′-thiobis (3-methyl-6-tert-butylphenol), 4,4′-dihydroxydiphenylsulfone, 2,4′-dihydroxydiphenylsulfone, 4-hydroxy-4′-isopropoxydiphenylsulfone, and bis ( 3-allyl-4-hydroxyl Nyl) sulfone, bis (p-hydroxyphenyl) butyl acetate, phenolic compounds such as methyl bis (p-hydroxyphenyl) acetate, 4-hydroxybenzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, 4- Propyl hydroxybenzoate, 4-hydroxybenzoate-sec-butyl, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, tolyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, 4,4′-dihydroxydiphenyl ether Phenolic compounds such as benzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, salicylic acid, 3-tert-butylsalicylic acid, 3-isopropylsalicylic acid, 3-benzylsalicylic acid, 3- (α -Methylbenzyl) salicylic acid, aromatic carboxylic acids such as 3,5-di-tert-butylsalicylic acid, and salts of these phenolic compounds and aromatic carboxylic acids with polyvalent metals such as zinc, magnesium, aluminum, calcium, etc. Organic acid substances such as Np-toluenesulfonyl-N′-3- (p-toluenesulfonyloxy) phenylurea, N- (p-toluenesulfonyl) -N ′-(p-butoxycarbonyl) urea, N- Examples include urea compounds such as p-toluenesulfonyl-N′-phenylurea.

  Among these developers, Np-toluenesulfonyl-N′-3 is used as the developer for the first thermosensitive coloring layer from the viewpoint of chemical resistance and sensitivity, and heat resistance during high temperature storage (background fogging). -(P-toluenesulfonyloxy) phenylurea, 4-hydroxy-4'-isopropoxydiphenylsulfone, 3,3'-diallyl-4,4'-dihydroxydiphenylsulfone, and 4-hydroxy-4'-allyloxydiphenyl It is preferable to use at least one selected from sulfones. From the viewpoint of background fogging during high temperature storage, Np-toluenesulfonyl-N′-3- is also used for the developer of the second thermosensitive coloring layer. (P-Toluenesulfonyloxy) phenylurea, 4-hydroxy-4′-isopropoxydiphenylsulfone, 3,3′-diallyl-4,4′-dihi It is preferable to use at least one selected from roxydiphenyl sulfone and 4-hydroxy-4′-allyloxydiphenyl sulfone, and as the color developer for the first thermosensitive color developing layer and the second thermosensitive color developing layer, From the viewpoint of background fogging, the same compound is preferred. Furthermore, among these, it is particularly preferable to use Np-toluenesulfonyl-N′-3- (p-toluenesulfonyloxy) phenylurea as a color developer for the first and second thermosensitive coloring layers. This is preferable.

  The amount of the developer used in the first thermosensitive coloring layer and the second thermosensitive recording layer is preferably about 100 to 1000 parts by mass with respect to 100 parts by mass of the total amount of the dye precursor. Preferably, it is used at a ratio of about 150 to 500 parts by mass. Furthermore, the content ratio of the diphenylsulfone crosslinkable compound represented by the above formula (1) of the present invention is arbitrary, but the diphenylsulfone crosslinkable compound represented by the above formula (1) is based on 100 parts by mass of the developer. It is particularly preferably about 1 to 90 parts by mass, specifically about 5 to 80 parts by mass.

  In the present invention, in order to improve color separation and light resistance, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3) is used as the ultraviolet absorber in the second thermosensitive coloring layer. It contains at least one selected from '-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole and 2- (2'-hydroxy-5'-tert-octylphenyl) benzotriazole.

  In the present invention, the second thermosensitive coloring layer may contain 10 to 30 parts by mass of hydroxypropylmethylcellulose with respect to 100 parts by mass of the total amount of the dye precursor that develops a color tone different from that of black coloring. This is preferable because it suppresses moisture-resistant skin fog. If the hydroxypropyl methylcellulose is less than 10 parts by mass, the effect of suppressing fogging is not sufficient, and if it exceeds 30 parts by mass, the surface strength may be lowered. Furthermore, as the hydroxypropylmethylcellulose used in the present invention, known ones can be used as appropriate, but it is preferable that the 2% aqueous solution has a viscosity at 20 ° C. of 6 cSt or less.

  Furthermore, in the present invention, it is preferable that the second thermosensitive coloring layer contains 5 to 70 parts by mass of a hindered amine compound with respect to 100 parts by mass of the total amount of the dye precursor that develops a color tone different from that of black coloring. And it is preferable in order to suppress fog-resistant skin fog. The hindered amine compound added to the second thermosensitive coloring layer is a compound represented by the following [Chemical Formula 3], a compound represented by [Chemical Formula 4] having a molecular weight of 2500 or more, and a molecular weight represented by [Chemical Formula 5] 2000. The above compounds, and further, compounds represented by [Chemical Formula 6] to [Chemical Formula 11] and the like, and commercial products can be used for all of them.

In the present invention, a first thermosensitive coloring layer containing a black color developing dye precursor and a developer is provided on a support, and further a dye that develops a color tone different from black coloring on the first thermosensitive coloring layer. In a multicolor thermosensitive recording material provided with a second thermosensitive color-developing layer containing a precursor and a developer, as a dye precursor that develops a color tone different from the black color in the second thermosensitive color-developing layer, 3,3- By containing bis (1-butyl-2-methylindol-3-yl) phthalide and 3-diethylamino-7-chlorofluorane, it is possible to achieve both color development sensitivity and color separation, and printing and blank paper storage stability (heat resistance Multi-color heat-sensitive recording material having excellent moisture resistance and light resistance) can be obtained. In particular, 3-diethylamino-7-chlorofluorane, which is an orange color, is added to 1 part by mass of 3,3-bis (1-butyl-2-methylindol-3-yl) phthalide, which is a purple color. By containing 5 parts by mass or more and 6.5 parts by mass or less , it is possible to obtain a heat-sensitive recording material which develops a color tone close to the normally desired red color of vermilion, more preferably 3 parts by mass or more, and 3.5 More preferred is part by mass or more . When the addition amount of 3 -diethylamino-7-chlorofluorane is less than 2.5 parts by mass, the color tone of low temperature color development is close to purple, and redness (purple color) during black color development of high temperature color becomes strong. , Color separation is deteriorated. On the other hand, when the addition amount of 3-diethylamino-7-chlorofluorane is 7.5 parts by mass or more, the storage stability of red coloring, particularly the light resistance, is significantly deteriorated.

In the present invention, from the viewpoints of color tone adjustment and storage stability of black color development, in the second thermosensitive color development layer, at least one organic polymer selected from polyurea and polyurea polyurethane, and a dye precursor that produces black color development, Composite particles consisting of can be used. The composite particles can be produced by a known method. For example, a method for producing composite particles in which the organic polymer is at least one of polyurea and polyurea-polyurethane will be described. The composite particles are prepared by dissolving and mixing a leuco dye and a polymer-forming raw material that forms at least one of polyurea and polyurea-polyurethane by polymerization in a water-insoluble organic solvent having a boiling point of 100 ° C. or less. Is emulsified and dispersed in a hydrophilic protective colloid solution such as polyvinyl alcohol so that the average particle size is about 0.5 to 3 μm, and if necessary, a reactive substance such as polyamine is further mixed, and then this emulsified dispersion is heated. The organic solvent is volatilized and removed, and then the polymer-forming raw material is polymerized, or the leuco dye is dissolved in the polymer-forming raw material, and this solution is used as described above. And after the emulsion is dispersed to an average particle size of about 0.5 to 3 μm, the polymer-forming raw material is polymerized.
Examples of the dye precursor in the composite particles contained in the second thermosensitive coloring layer include 3-di (n-pentyl) amino-6-methyl-7-anilinofluorane and 3-di (n-butyl). Amino-7- (2-chloroanilino) fluorane, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, and 3-diethylamino-6-methyl-7- (3-toluidino) fluorane It is more preferable in that it hardly causes background fogging.

  The composite particles used in the present invention include 3,3′-bis (4-diethylamino-2-ethoxy) in order to improve the readability with a barcode reader, in addition to a black color-forming dye precursor. Absorption in the near infrared region such as phenyl) -4-azaphthalide, 3- [2,2-bis (1-ethyl-2-methylindol-3-yl) vinyl] -3- (4-diethylaminophenyl) phthalide A dye precursor, an aromatic organic compound (sensitizer) having a melting point of about 40 to 150 ° C. to increase recording sensitivity, if necessary, an ultraviolet absorber, an antioxidant, and oil-soluble fluorescence to increase light resistance A dye, a release agent, or the like may be added.

  In the present invention, an image stabilizer may be used mainly for improving the storage stability of the color-recorded image. Examples of such an image stabilizer include 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-ethylenebis (4-methyl-6-tert-butylphenol), 2, 2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,2'-methylenebis (4,6-di-tert-butylphenol), 2,2'-ethylidenebis (4,6-di-tert- Butylphenol), 2,2'-ethylidenebis (4-methyl-6-tert-butylphenol), 2,2'-ethylidenebis (4-ethyl-6-tert-butylphenol), 2,2 '-(2,2 -Propylidene) bis (4,6-di-tert-butylphenol), 2,2'-methylenebis (4-methoxy-6-tert-butyl) Enol), 2,2′-methylenebis (6-tert-butylphenol), 4,4′-thiobis (3-methyl-6-tert-butylphenol), 4,4′-thiobis (2-methyl-6-tert- Butylphenol), 4,4′-thiobis (5-methyl-6-tert-butylphenol), 4,4′-thiobis (2-chloro-6-tert-butylphenol), 4,4′-thiobis (2-methoxy-) 6-tert-butylphenol), 4,4′-thiobis (2-ethyl-6-tert-butylphenol), 4,4′-butylidenebis (6-tert-butyl-m-cresol), 1- [α-methyl- α- (4′-hydroxyphenyl) ethyl] -4- [α ′, α′-bis (4 ″ -hydroxyphenyl) ethyl] benzene, 1,1 , 3-Tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 4,4′- Thiobis (3-methylphenol), 4,4′-dihydroxy-3,3 ′, 5,5′-tetrabromodiphenyl sulfone, 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethyldiphenyl Sulfone, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2-bis (4-hydroxy-3) , 5-dimethylphenyl) propane, a hindered phenol compound, N, N′-di-2-naphthyl-p-phenylenediamine, 2,2′-methylenebis (4 6-di-tert-butylphenyl) sodium phosphate, 1,1-bis (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 4,4 ′-[1,4-phenylenebis (1 -Methylethylidene)] bisphenol and phenolic compounds such as 4,4 '-[1,3-phenylenebis (1-methylethylidene)] bisphenol, 4-benzyloxyphenyl-4'-(2-methyl-2 , 3-epoxypropyloxy) phenylsulfone, 4- (2-methyl-1,2-epoxyethyl) diphenylsulfone, and 4- (2-ethyl-1,2-epoxyethyl) diphenylsulfone, and the like, and 1,3,5-tris (2,6-dimethylbenzyl-3-hydroxy-4-tert-butyl) isocyanuric acid Can be used include one or more selected from Anuru acid compound. Of course, the image stabilizer is not limited to these, and two or more kinds of compounds may be used in combination as required.

  In order to adjust the color development sensitivity of the thermosensitive coloring layer of the multicolor thermosensitive recording material, a thermofusible substance can be contained in the thermosensitive coloring layer as a sensitizer. As the sensitizer, a compound conventionally known as a sensitizer for a heat-sensitive recording material can be used. For example, stearic acid amide, methoxycarbonyl-N-stearic acid benzamide, N-benzoyl stearic acid amide, N -Eicosanoic acid amide, ethylene bistearic acid amide, behenic acid amide, methylenebis stearic acid amide, N-methylol stearic acid amide, dibenzyl terephthalate, dimethyl terephthalate, dioctyl terephthalate, benzyl p-benzyloxybenzoate, 1- Hydroxy-2-naphthoic acid phenyl, 2-naphthylbenzyl ether, m-terphenyl, oxalic acid dibenzyl ester, oxalic acid-di-p-methylbenzyl ester, oxalic acid-di-p-chlorobenzyl ester, p-benzyl Biphenyl, Rilbiphenyl ether, di (p-methoxyphenoxyethyl) ether, 1,2-di (3-methylphenoxy) ethane, 1,2-di (4-methylphenoxy) ethane, 1,2-di (4-methoxyphenoxy) ) Ethane, 1,2-di (4-chlorophenoxy) ethane, 1,2-diphenoxyethane, 1- (4-methoxyphenoxy) -2- (2-methylphenoxy) ethane, p-methylthiophenylbenzyl ether, 1,4-di (phenylthio) butane, p-acetoluidide, p-acetophenetide, N-acetoacetyl-p-toluidine, di (β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1 -Isopropylphenyl-2-phenylethane, dibenzyl terephthalate, 1-hydroxy-2-naphtho Mention may be made of phenyl ethate, di-o-chlorobenzyl adipate, 1,2-bis (3,4-dimethylphenyl) ethane, 1,3-bis (2-naphthoxy) propane and the like. In particular, when oxalic acid di-p-methylbenzyl ester and oxalic acid di-p-chlorobenzyl ester are used as a sensitizer, a sensitizing effect with less background fogging can be obtained. The amount of these sensitizers to be used is not particularly limited, but it is generally desirable to adjust in a range of 4 parts by mass or less with respect to 1 part by mass of the developer.

  Additives such as a developer, an image stabilizer and a sensitizer used in the present invention are dispersed in water in the same manner as when the dye precursor is used in a solid fine particle state, and the heat-sensitive coloring layer forming coating What is necessary is just to mix with this in the case of preparation. Moreover, these additives can be dissolved in a solvent and emulsified in water using a water-soluble polymer compound as an emulsifier. Furthermore, composite fine particles containing these compounds may be prepared by the same method as the composite fine particle preparation method described above, and this may be contained in the thermosensitive coloring layer. Further, the image stabilizer and the sensitizer may be contained in the composite fine particles containing the dye precursor. In particular, the color sensitivity can be adjusted to a desired value by incorporating a sensitizer into the composite fine particles together with the dye precursor.

  In the present invention, in order to improve the whiteness of the thermosensitive coloring layer and improve the uniformity of the image, a fine pigment having a high whiteness and an average particle size of 10 μm or less can be contained in the thermosensitive coloring layer. For example, calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcined clay, silica, diatomaceous earth, synthetic aluminum silicate, zinc oxide, titanium oxide, aluminum hydroxide, barium sulfate, surface treated inorganic pigments such as calcium carbonate and silica In addition, organic pigments such as urea-formalin resin, styrene-methacrylic acid copolymer resin, and polystyrene resin can be used. In order to prevent residue adhesion and sticking to the thermal head, it is preferable to use a pigment having an oil absorption of 50 ml / 100 g or more. The amount of the pigment blended is preferably an amount that does not decrease the color density, that is, 50% by mass or less based on the total solid content of the heat-sensitive color developing layer.

  In the present invention, an adhesive is used as another component material constituting the thermosensitive coloring layer, and a crosslinking agent, a wax, a metal soap, a colored dye, a colored pigment, and a fluorescent dye can be used as necessary. . Examples of the adhesive include polyvinyl alcohol and derivatives thereof, starch and derivatives thereof, cellulose derivatives such as hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide-acrylic acid ester Water-soluble polymer materials such as polymers, acrylamide-acrylic acid ester-methacrylic acid ester copolymers, styrene-maleic anhydride copolymers, isobutylene-maleic anhydride copolymers, casein, gelatin and derivatives thereof, and , Polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylate, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, ethylene-vinyl acetate copolymer Emulsions and styrene body such as - butadiene copolymer, styrene - butadiene - can be given latex water-insoluble polymer such as an acrylic copolymer.

  Moreover, in order to improve the water resistance of the thermosensitive coloring layer, a crosslinking agent for three-dimensionally curing the adhesive can be contained in the thermosensitive coloring layer. For example, aldehyde compounds such as glyoxal, polyamine compounds such as polyethyleneimine, epoxy compounds, polyamide resins, melamine resins, dimethylol urea compounds, aziridine compounds, blocked isocyanate compounds, carboxylic acid dihydrazide compounds, ammonium persulfate and chloride Ferric and inorganic compounds such as magnesium chloride, sodium tetraborate and potassium tetraborate, or at least one cross-linkable compound selected from boric acid, boric acid triester, boron-based polymer, etc. in the total solid content of the thermosensitive coloring layer On the other hand, it is preferably used in the range of 1 to 10% by mass.

  Examples of the wax added to the thermosensitive coloring layer include waxes such as paraffin wax, carnauba wax, microcrystalline wax, polyolefin wax, and polyethylene wax, and higher fatty acid amides such as stearamide, ethylenebisstearic amide, and the like. Examples thereof include fatty acid esters and derivatives thereof. In particular, when methylolated fatty acid amide is added to the thermosensitive coloring layer, a sensitizing effect can be obtained without deteriorating the background fog resistance.

  Examples of the metal soap added to the heat-sensitive color developing layer include higher fatty acid polyvalent metal salts such as zinc stearate, aluminum stearate, calcium stearate, and zinc oleate. Further, the inclusion of a colored dye and / or a colored pigment having a color tone complementary to the low temperature color tone in the heat-sensitive color developing layer is preferably used for adjusting the color tone of the recording material before printing. If necessary, various additives such as an oil repellent, an antifoaming agent, and a viscosity modifier can be further added to the thermosensitive coloring layer within a range not impairing the effects of the present invention.

In the present invention, when the dye precursor is used in a solid fine particle state, the leuco dye is pulverized by various wet pulverizers such as a sand grinder, an attritor, a ball mill, and a cobo mill using water as a dispersion medium. In addition to water-soluble synthetic polymer compounds such as modified polyvinyl alcohols such as acrylamide, polyvinylpyrrolidone, polyvinyl alcohol, sulfone-modified polyvinyl alcohol, methylcellulose, carboxymethylcellulose, hydroxypropylmethylcellulose, styrene-maleic anhydride copolymer salts and derivatives thereof If necessary, it can be dispersed in a dispersion medium together with a surfactant, an antifoaming agent and the like to form a dispersion, and this dispersion can be used for preparing a coating solution for a thermosensitive coloring layer.
Alternatively, after the dye precursor is dissolved in a solvent, the solution is emulsified and dispersed in water using the above water-soluble polymer as a stabilizer, and then the solvent is evaporated from the emulsion to make the dye precursor into solid fine particles. it can. In any case, the average particle size of the dispersed particles of the dye precursor used in the solid fine particle state is preferably about 0.2 to 3.0 μm, more preferably 0.3 in order to obtain an appropriate color development sensitivity. ˜1.5 μm.

  Various auxiliary agents can be added to the coating solution for the thermosensitive coloring layer as required. For example, surfactants, waxes, metal soaps, antifoaming agents, fluorescent dyes, colored dyes, crosslinking agents, viscosity modifiers, and the like are added as appropriate.

  In the present invention, as a method of forming each thermosensitive coloring layer, any of known coating methods such as an air knife method, a blade method, a gravure method, a roll coater method, a spray method, a dip method, a bar method, and a curtain method is used. However, the curtain method is more preferable for further improving the effects of the present invention, particularly the color separation property.

  In the present invention, the curtain coating method is a method in which the coating liquid is allowed to flow down and fall freely, and is applied to the support in a non-contact manner. A known method such as a slide curtain method, a couple curtain method, or a twin curtain method is employed. There is no particular limitation. Further, as described in Japanese Patent Application Laid-Open No. 2006-247611, the paint is ejected downward from the curtain head to form a paint layer on the slope, and the paint curtain is formed from the downward curtain guide portion of the slope. The paint layer can also be transferred onto the web surface. The thermal recording layers can be applied alone or simultaneously, but the first thermal coloring layer and the second thermal coloring layer can be further reduced in terms of production efficiency and energy consumption during production. Are preferably applied simultaneously in multiple layers. It should be noted that various conditions such as coating concentration, coating speed, curtain film width, drop angle, and the like are desirably adjusted appropriately according to each curtain coating method and coating apparatus. Since these curtain coating methods are non-contact contour coating, a coating layer having a uniform thickness can be obtained. On the other hand, contact type coating such as blade, bar, and air knife coating is affected by the surface properties (unevenness) of the support, and therefore the film thickness becomes non-uniform. For this reason, with the same coating amount, the heat-sensitive color forming layer formed by curtain coating can obtain better color separation and better image quality, and also improve image storage stability.

  When the thermosensitive coloring layer is formed by the curtain coating method, a surfactant is added to the coating solution for the thermosensitive coloring layer in order to stabilize the curtain film by adjusting the surface tension. Surfactants include, for example, sulfosuccinic acid alkali metal salts, alkylbenzene sulfonates, acetylene glycol compounds, fluorine surfactants, silicon surfactants, phosphate ester surfactants, and ether type surfactants. Agents, amphoteric surfactants such as betaine, aminocarboxylate, and imidazoline derivatives. The addition amount of the surfactant is preferably about 0.05 to 3.0% by mass with respect to the total solid content of the thermosensitive coloring layer. If it is less than 0.05% by mass, the effect of addition is small and the surface tension is not sufficiently lowered, and the curtain film is likely to be cut. If it exceeds 3 mass%, the coating liquid tends to foam and causes coating defects. From the balance between the effect and the physical properties of the paint, the more preferable content of the surfactant is about 0.10 to 2.0% by mass.

The coating amount of each heat-sensitive coloring layer coating liquid is not particularly limited, and the desired quality can be achieved if the dry weight is about 0.5 to 10 g / m ² , particularly about 1 to 6 g / m ² . The thermosensitive recording layer can be divided into three or more layers as necessary, and the composition and coating amount of each layer can be changed.

(Protective layer)
In the present invention, a protective layer may be provided on the thermosensitive coloring layer as necessary. As the protective layer, a protective layer that has been used in conventionally known heat-sensitive recording materials can be used. The protective layer is mainly composed of a pigment and an adhesive. In particular, a lubricant such as polyolefin wax or zinc stearate is preferably added to the protective layer for the purpose of preventing sticking to the thermal head, and an ultraviolet absorber can also be included. In addition, the added value of the product can be increased by providing a glossy protective layer.

  The protective layer is preferably composed mainly of a water-soluble polymer and / or a synthetic resin emulsion.

  Examples of the water-soluble polymer include polyvinyl alcohols such as fully saponified or partially saponified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, and silicon-modified polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, and carboxymethyl cellulose. Cellulose resins such as gelatin, casein, alkali salts of styrene / maleic anhydride copolymers, alkali salts of ethylene / acrylic acid copolymers, alkali salts of styrene / acrylic acid copolymers, and the like.

  Examples of the synthetic resin emulsion include latexes such as styrene-butadiene latex, acrylic latex, and urethane latex.

  Among them, acetoacetyl-modified polyvinyl alcohol and diacetone-modified polyvinyl alcohol are preferably used because they can improve the surface barrier properties and improve the storage stability such as chemical resistance.

  The total content of the water-soluble polymer and / or synthetic resin emulsion is preferably about 10 to 80% by mass, and more preferably about 20 to 75% by mass, based on the total solid content of the protective layer.

  If it is less than 10% by mass, not only the barrier property is not sufficient, but also the surface strength is lowered, leading to deterioration of paper dust and the like. On the other hand, if it exceeds 80% by mass, sticking may be deteriorated.

  When the water-soluble polymer and the synthetic resin emulsion are used in combination, the usage ratio of the synthetic resin emulsion is about 5 to 100 parts by mass with respect to 100 parts by mass of the water-soluble polymer.

  Examples of the pigment include inorganic pigments such as calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, amorphous silica, synthetic mica, aluminum hydroxide, barium sulfate, talc, kaolin, clay, calcined kaolin, nylon resin filler, urea -Organic pigments such as formalin resin filler and raw starch particles.

  Of these, kaolin and aluminum hydroxide are preferred because they have a small decrease in barrier properties against chemicals such as plasticizers and oils, and a small decrease in recording density.

  The usage-amount of a pigment is about 5-80 mass% with respect to the total solid of a protective layer, and the range of about 10-70 mass% is especially preferable.

  If it is less than 5% by mass, slipping with the thermal head is deteriorated, causing sticking or deteriorating head wrinkles. On the other hand, when it exceeds 80 mass%, barrier property will worsen and the function as a protective layer will fall significantly.

  As the auxiliary agent, for example, lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax, sodium alkylbenzene sulfonate, sodium dioctyl sulfosuccinate, sulfone-modified polyvinyl alcohol, sodium acrylate glycol polyacrylate compound , Surfactants such as fluorosurfactants, silicon surfactants, phosphate ester surfactants, ether surfactants, or amphoteric surfactants such as betaines, aminocarboxylates, and imidazoline derivatives, Glyoxal, boric acid, dialdehyde starch, methylol urea, epoxy compound, hydrazine compound, etc., water resistance (crosslinking agent), hydrophobic polycarboxylic acid copolymer, UV absorber, fluorescent dye, coloring dye Mold release agents, antioxidants, and the like. The usage-amount of auxiliary agent can be suitably set from a wide range.

  In the present invention, the means for coating and forming the protective layer is not particularly limited, and air knife method, blade method, gravure method, roll coater method, curtain coater method, spray method, dip method, bar method, and extrusion method. Any known coating method such as the above may be used, but it is preferable to use a curtain coating method for improving the barrier property, and the first thermosensitive coloring layer, the second thermosensitive coloring layer, and the protective layer are simultaneously multilayered. Curtain coating is particularly preferable in terms of increasing production efficiency and reducing energy consumption during production. Although it does not specifically limit as a coating device used for curtain coating, An extrusion hopper type curtain coating device, a slide hopper type curtain coating device, or the method described in Japanese Patent Application Laid-Open No. 2006-247611 mentioned above can be used.

The coating amount of the protective layer coating liquid is not particularly limited, and a desired quality can be achieved if the dry weight is about 0.3 to 10 g / m ² , particularly about 0.5 to 8 g / m ² . The protective layer can be divided into two or more layers as required, and the composition and coating amount of each layer can be changed.

  After application of the coating liquid, it is dried, and thereafter, it is preferably smoothed by calendaring and used.

(Undercoat layer)
In the present invention, it is preferable to provide an undercoat layer between the support and the thermosensitive coloring layer, since the smoothness of the support surface can be enhanced and heat insulation can be imparted. The undercoat layer is mainly composed of a pigment and an adhesive. As the pigment, all of general inorganic and organic pigments can be added. Specific examples include calcined kaolin, aluminum oxide, magnesium carbonate, calcined diatomaceous earth, aluminum silicate, calcium carbonate, barium sulfate, aluminum hydroxide, kaolin, amorphous And inorganic pigments such as porous silica and talc, and organic pigments such as plastic hollow particles and dense particles. The total amount of the pigment is preferably about 40 to 85% by mass with respect to the total solid content of the undercoat layer.

  Examples of the adhesive for the undercoat layer include water-soluble polymers and aqueous binders. These may be used alone or in combination of two or more. Examples of the water-soluble polymer include starch, modified starch, polyvinyl alcohol, modified polyvinyl alcohol, acrylamide, carboxymethyl cellulose, and casein. As the aqueous binder, synthetic rubber latex and synthetic resin emulsion are common. Yes, for example, styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, vinyl acetate emulsion and the like.

  The amount of the adhesive used for the undercoat layer is determined in consideration of the coating strength and the color development sensitivity of the thermosensitive color developing layer, but is preferably about 3 to 100% by mass relative to the mass of the pigment contained in the undercoat layer. About 5-50 mass% is more preferable, and about 7-40 mass% is especially preferable. Moreover, you may add a thickener, a wax, an antifoamer, surfactant, etc. in an undercoat layer as needed.

As a method for forming an undercoat layer on a support, known coating methods such as an air knife method, a blade method, a gravure method, a roll coater method, a curtain coater method, a spray method, a dip method, a bar method, and an extrusion method are used. Either method may be used, but the blade method is particularly preferable from the viewpoint of print image quality. The coating amount, dry weight from 1 to 20 g / ^{m 2} approximately, is adjusted preferably in the range of about 3~12g / ^{m 2.} Examples of the support include high-quality paper, art paper, synthetic paper, PET film, non-woven fabric medium paper, coated paper, cast coated paper, glassine paper, resin-laminated paper, polyolefin-based synthetic paper, synthetic fiber paper, non-woven fabric, and synthetic resin. In addition to films, various transparent supports can be appropriately selected and used.

  The method using the blade coater is not limited to a coating method using a bevel type or a vent type blade, but also includes a rod blade method and a bill blade method, and is not limited to an off-machine coater. You may apply with the installed on-machine coater.

  In the present invention, in order to increase the added value of the multicolor thermosensitive recording material, the multicolor thermosensitive recording material can be further processed to give a higher function. For example, it can be used as a pressure-sensitive adhesive paper, a re-humidified adhesive paper, or a delayed tack paper by applying a coating process such as a pressure-sensitive adhesive, a re-humidifying adhesive, or a delayed tack type pressure-sensitive adhesive on the back surface. Or it can also be set as the thermosensitive recording body which has a layer which can be magnetic-recorded in a back surface by giving magnetic processing. In particular, those subjected to adhesive processing and magnetic processing are useful for applications such as heat-sensitive labels and heat-sensitive magnetic tickets. In addition, by using the back surface, a function of thermal transfer paper, ink jet paper, carbonless paper, electrostatic recording paper, and xerographic paper can be added to the recording material to enable double-sided recording. Of course, a double-sided thermal recording material can also be used.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” and “%” in the examples represent “part by mass” and “% by mass”, respectively.

Example 1
(Preparation of coating solution for undercoat layer)
60 parts of calcined kaolin having an oil absorption of 110 ml / 100 g, 80 parts of plastic hollow particle emulsion (trade name: AE852, solid content concentration 26%, volume hollowness 55%, average particle size 1.0 μm, manufactured by JSR), as an adhesive 20 parts of styrene / butadiene / acrylonitrile copolymer latex having a solid concentration of 50%, 20 parts of 5% aqueous solution of carboxymethylcellulose (trade name: Cellogen 7A, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), oxidized starch (trade name: Oji Ace A, An undercoat layer coating solution was obtained by uniformly mixing and stirring 25 parts of a 20% aqueous solution of Oji Cornstarch Co., Ltd. and 90 parts of water.

(Preparation of base paper with an undercoat layer)
A base paper having an undercoat layer formed on one surface of a high-quality paper having a basis weight of 60 g / m ² is coated with a blade coater so that the coating amount after drying is 7 g / m ² and dried. It was.

(Preparation of thermal recording layer coating solution)
-Preparation of Dye Precursor Dispersion (Liquid A) 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane, sulfone-modified polyvinyl (Goceran L-3266: Nihon Gosei) 10 parts of 20% aqueous solution of Chemical Industries, Ltd. and 20 parts of water were pulverized and dispersed using a vertical sand mill (made by IMEX Co., Ltd., sand grinder) so that the average particle size was 0.8 μm.

-Preparation of Dye Precursor Dispersion (Liquid B) 3-Di (n-butyl) amino-6-methyl-7-anilinofluorane, 20 parts of sulfone-modified polyvinyl (Goselan L-3266: Nippon Synthetic Chemical Industry) 10 parts of 20% aqueous solution and 20 parts of water were pulverized and dispersed using a vertical sand mill (Immex Co., Ltd., sand grinder) so that the average particle diameter was 0.8 μm.

-Preparation of Dye Precursor Dispersion (Liquid C) 3,3'-bis (1-n-butyl-2-methylindol-3-yl) phthalide 20 parts, sulfone-modified polyvinyl (trade name: Goceran L- 3266, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 10 parts of 20% aqueous solution and 20 parts of water were pulverized and dispersed using a vertical sand mill (made by IMEX Co., Ltd., sand grinder) so that the average particle size became 0.7 μm. did.

Preparation of Dye Precursor Dispersion (Liquid D) 10 parts of 20% aqueous solution of 3-diethylamino-7-chlorofluorane, 20 parts of sulfone-modified polyvinyl (trade name: Gocelan L-3266, manufactured by Nippon Synthetic Chemical Industry) Then, 20 parts of water was pulverized and dispersed using a vertical sand mill (made by Imex Co., Ltd., sand grinder) so that the average particle size became 0.7 μm.

Preparation of Dye Precursor Dispersion (Liquid E) 3-Di (n-butyl) amino-6-methyl-7-bromofluorane (20 parts), sulfone-modified polyvinyl (trade name: Goceran L-3266, Nihon Gosei) 10 parts of a 20% aqueous solution and 20 parts of water were pulverized and dispersed using a vertical sand mill (made by IMEX Co., Ltd., sand grinder) so that the average particle size was 0.7 μm.

Preparation of dye precursor-containing composite particle dispersion (liquid F) 3-di (n-pentyl) amino-6-methyl-7-anilinofluorane 6 parts and 2-hydroxy-4-octyl as an ultraviolet absorber 3 parts of oxybenzophenone was dissolved in 9 parts of dicyclohexylmethane-4,4′-diisocyanate heated to 100 ° C., this solution was cooled to 35 ° C., and then 8% polyvinyl alcohol (trade name, manufactured by Nippon Synthetic Chemical Industry, trade name). : Gohsenol GM-14L) The mixture was gradually added to 100 parts of an aqueous solution and emulsified and dispersed by stirring at a rotation speed of 8000 rpm using a homogenizer, and then 60 parts of water was added to the emulsified dispersion to make it uniform. The emulsion dispersion was heated to 90 ° C. and allowed to undergo a curing reaction for 10 hours, and then water was added so that the solid content concentration was 20%, and a composite particle dispersion having an average particle diameter of 0.8 μm was obtained. Obtained.

-Preparation of developer dispersion (liquid G) Np-toluenesulfonyl-N'-3- (p-toluenesulfonyloxy) phenylurea 20 parts, sulfone-modified polyvinyl (trade name: Goceran L-3266, 10 parts of a 20% aqueous solution (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and 20 parts of water were pulverized and dispersed using a vertical sand mill (a sand grinder, manufactured by IMEX Co., Ltd.) so that the average particle diameter was 1.2 μm.

-Preparation of developer dispersion (solution H) 20 parts of 4-hydroxy-4'-isopropoxydiphenylsulfone, 20% aqueous solution of sulfone-modified polyvinyl (trade name: Gocelan L-3266, manufactured by Nippon Synthetic Chemical Industry) 10 parts and 20 parts of water were pulverized and dispersed using a vertical sand mill (a sand grinder manufactured by IMEX Co., Ltd.) so that the average particle diameter was 1.2 μm.

・ Preparation of developer dispersion (liquid I) 3,3′-diallyl-4,4′-dihydroxydiphenylsulfone 20 parts, sulfone-modified polyvinyl (trade name: Gocelan L-3266, manufactured by Nippon Synthetic Chemical Industry) 10 parts of the 20% solution and 20 parts of water were pulverized and dispersed using a vertical sand mill (a sand grinder, manufactured by IMEX Co., Ltd.) so that the average particle diameter was 1.2 μm.

-Preparation of developer dispersion (solution J) 20 parts of 4-hydroxy-4'-allyloxydiphenylsulfone, sulfone-modified polyvinyl (trade name: Goceran L-3266, manufactured by Nippon Synthetic Chemical Industry) 10 parts and 20 parts of water were pulverized and dispersed using a vertical sand mill (a sand grinder manufactured by IMEX Co., Ltd.) so that the average particle diameter was 1.2 μm.

-Preparation of dispersion of UV absorber (liquid K) 2- (2'-hydroxy-5'-methylphenyl) benzotriazole (trade name: JF77T, manufactured by Johoku Chemical Co., Ltd.), sulfone-modified polyvinyl (trade name) : Goceran L-3266, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 10 parts of 20% aqueous solution and 20 parts of water using a vertical sand mill (made by Imex Co., Ltd., sand grinder), the average particle diameter becomes 1.0 μm. So that it was pulverized and dispersed.

Preparation of UV absorber dispersion (liquid L) 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole (trade name: JF79, manufactured by Johoku Chemical Co., Ltd.) ) 20 parts, 10 parts of a 20% aqueous solution of sulfone-modified polyvinyl (trade name: Gocelan L-3266, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), and 20 parts of water using a vertical sand mill (made by IMEX Co., Ltd., sand grinder). Then, the particles were pulverized and dispersed so that the average particle size was 1.0 μm.

Preparation of UV absorber dispersion (liquid M) 2- (2′-hydroxy-5′-tert-octylphenyl) -benzotriazole (trade name: JF83, manufactured by Johoku Chemical Co., Ltd.) 20 parts, sulfone-modified polyvinyl (Product name: Goceran L-3266, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 10 parts of a 20% aqueous solution and 20 parts of water using a vertical sand mill (made by IMEX Co., Ltd., sand grinder) have an average particle size of 1. The mixture was pulverized and dispersed to 0 μm.

-Preparation of diphenylsulfone cross-linking compound dispersion (N liquid) Compound represented by the general formula (1) (trade name: D-90, n is 1 to 7 in total content of 87% by mass, Nippon Soda 20 parts of a 20% aqueous solution of sulfonic acid-modified polyvinyl alcohol and 20 parts of water using a vertical sand mill (Imex Co., Ltd., sand grinder), the average particle size is 1.0 μm. The mixture was pulverized and dispersed so that

Preparation of hindered amine compound dispersion (liquid O) Poly {[6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl)] [( 2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino]} (trade name: Light Ace HS944, Sakai Chemical Co., Ltd. 20 parts), 20 parts of sulfone-modified polyvinyl (trade name: Goseiran L-3266, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), 20 parts of water, vertical sand mill (Eimex Co., Ltd., sand grinder). And then pulverized and dispersed so that the average particle size was 1.0 μm.

・ Preparation of coating liquid for first thermosensitive coloring layer A part 45 parts, G part 90 parts, N part 10 parts, plastic hollow particles (trade name: AE852, solid content concentration 26%, hollow rate 55%, manufactured by JSR) 50 parts, 50 parts of 15% aqueous solution of diacetone-modified polyvinyl alcohol (trade name: DF-10, degree of polymerization 1000, manufactured by Nihon Vinegar Bipoval), SBR latex (trade name: L-1571, solid concentration 48%, Asahi Kasei Chemicals) 8 parts, 8 parts of 35% aqueous solution of adipic acid dihydrazide, 4 parts of 10% aqueous solution of dioctylsulfosuccinic acid sodium salt (trade name: SN Wet OT-70, manufactured by San Nopco) A coating solution for a thermosensitive coloring layer was obtained.

-Preparation of coating liquid for second thermosensitive coloring layer C part 8 parts, D part 40 parts, G part 84 parts, K part 30 parts, diacetone modified polyvinyl alcohol (trade name: DF-10, polymerization degree 1000, Nippon Vinegar Bipovar 50 parts of 15% aqueous solution, 20 parts of 15% aqueous solution of hydroxypropylmethylcellulose (trade name: Metrolose 60SH-03, manufactured by Shin-Etsu Chemical Co., Ltd.), SBR latex (trade name: L-1571, solid content concentration 48%, Asahi Kasei Chemicals), 8 parts of 35% aqueous solution of adipic acid dihydrazide, and 4 parts of 10% aqueous solution of dioctylsulfosuccinic acid sodium salt (trade name: SN Wet OT-70, manufactured by San Nopco) A coating solution for a thermosensitive coloring layer was obtained.

-Preparation of coating solution for protective layer Diacetone-modified polyvinyl alcohol (trade name) was added to a dispersion obtained by dispersing 50 parts of aluminum hydroxide (trade name: Hygielite H-42M, manufactured by Showa Denko KK) in 50 parts of water. : 600 parts of 10% aqueous solution of DF-10, degree of polymerization 1000, manufactured by Nihon Vinegar Bipoval), zinc stearate (trade name: Hydrin Z-8-36, solid content concentration 36%, manufactured by Chukyo Yushi Co., Ltd.), 10 parts of 35% aqueous solution of adipic acid dihydrazide and 20 parts of 5% aqueous solution of sodium dioctylsulfosuccinate (trade name: SN Wet OT-70, manufactured by San Nopco) were mixed and stirred to obtain a coating solution for a protective layer.

-Preparation of multicolor thermosensitive recording material On the base paper on which the undercoat layer prepared above was formed, the first thermosensitive coloring layer coating solution, the second thermosensitive coloring layer coating solution and the protective layer coating solution were each dried. The undercoat layer, the first thermosensitive coloring layer, the second thermosensitive coloring layer, and the protective layer are sequentially applied by coating and drying by a rod coating method so that the coating amount becomes 4 g / m ² , 3 g / m ² , and 2 g / m ^2. After obtaining the multicolor heat-sensitive recording material, the multicolor heat-sensitive recording material was prepared by smoothing with a super calendar so that the Beck smoothness (JIS-P8119) of the heat-sensitive recording surface was 4000 seconds.

Example 2
A multicolor thermosensitive recording material was prepared in the same manner as in Example 1, except that the liquid for the second thermosensitive coloring layer of Example 1 was prepared by using 12 parts of C solution and 36 parts of D solution.

Example 3 (Reference Example)
A multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that 6 parts of the C solution and 42 parts of the D solution were prepared in the preparation of the coating solution for the second thermosensitive coloring layer of Example 1.

Example 4
A multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that 30 parts of L solution was used instead of K solution in the preparation of the second thermosensitive coloring layer coating solution of Example 1.

Example 5
A multicolor thermosensitive recording material was produced in the same manner as in Example 1 except that in the preparation of the coating solution for the second thermosensitive coloring layer of Example 1, 30 parts of M solution was used instead of K solution.

Example 6
A multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that in the preparation of the coating solution for the first thermosensitive coloring layer of Example 1, 45 parts of B liquid was used instead of 45 parts of A liquid.

Example 7
In the preparation of the coating solution for the second thermosensitive coloring layer of Example 1, Example 1 was used except that 20 parts of a 15% aqueous solution of hydroxypropylmethylcellulose (trade name: Metrolose 60SH-03, manufactured by Shin-Etsu Chemical Co., Ltd.) was not added. Similarly, a multicolor thermosensitive recording material was produced.

Example 8
A multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that 6 parts of O solution was added in the preparation of the second thermosensitive coloring layer coating solution of Example 1.

Example 9
In the preparation of the coating solution for the first thermosensitive coloring layer of Example 1, plastic solid particles (trade name: Grosdale 130S, solid content concentration 53%) instead of 50 parts of plastic hollow particles (trade name: AE852, supra). (Manufactured by Mitsui Chemicals, Inc.) A multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that 25 parts were added.

Example 10
In preparing the first thermosensitive coloring layer coating solution of Example 1, aluminum hydroxide (trade name: Heidilite H-42M, manufactured by Showa Denko KK) instead of 50 parts of plastic hollow particles (trade name: AE852, supra) A multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that 26 parts of a dispersion obtained by dispersing 50 parts in 50 parts of water was added.

Example 11
A multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that 15 parts of N solution was not added in the preparation of the first thermosensitive coloring layer coating solution of Example 1.

Example 12
In the preparation of the first thermosensitive coloring layer coating solution of Example 1, 90 parts of H solution was added instead of 90 parts of G solution, and in the preparation of the second thermosensitive coloring layer coating solution, 84 parts of G solution was added. Instead, a multicolor thermosensitive recording material was produced in the same manner as in Example 1 except that 84 parts of the H liquid was added.

Example 13
In the preparation of the first thermosensitive coloring layer coating solution of Example 1, 90 parts of I solution was added instead of 90 parts of G solution, and in the preparation of the second thermosensitive coloring layer coating solution, 84 parts of G solution was added. Instead, a multicolor thermosensitive recording material was produced in the same manner as in Example 1 except that 84 parts of I liquid was added.

Example 14
In the preparation of the first thermosensitive coloring layer coating solution of Example 1, 90 parts of J solution was added instead of 90 parts of G solution, and in the preparation of the second thermosensitive coloring layer coating solution, 84 parts of G solution was added. Instead, a multicolor thermosensitive recording material was produced in the same manner as in Example 1 except that 84 parts of J solution was added.

Example 15
A multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that 30 parts of the F solution was added in the preparation of the second thermosensitive coloring layer coating solution of Example 1.

Example 16
In the production of the multicolor thermosensitive recording material of Example 1, instead of the rod coating method, the first thermosensitive coloring layer coating solution, the second thermosensitive coloring layer coating solution, and the protective layer coating solution were respectively applied by the curtain coating method. A multicolor thermosensitive recording material was produced in the same manner as in Example 1 except that the coating and drying were successively performed.

Example 17
In the production of the multicolor thermosensitive recording material of Example 1, instead of the rod coating method, the first thermosensitive coloring layer coating solution, the second thermosensitive coloring layer coating solution and the protective layer coating solution were simultaneously applied by the curtain coating method. A multicolor thermosensitive recording material was produced in the same manner as in Example 1 except that the multilayer coating and drying were performed.

Comparative Example 1
・ Preparation of coating solution for thermosensitive coloring layer 5 parts of C solution, 25 parts of D solution, 70 parts of F solution, 90 parts of G solution, diacetone modified polyvinyl alcohol (trade name: DF-10, polymerization degree 1000, manufactured by Nihon Vinegar Bipoval) ), 15 parts aqueous solution of hydroxypropylmethylcellulose (trade name: Metroles 60SH-03, manufactured by Shin-Etsu Chemical Co., Ltd.), 20 parts of 15% aqueous solution, SBR latex (trade name: L-1571, solid content concentration 48%, Asahi Kasei Chemicals) 8 parts, 8 parts of 35% aqueous solution of adipic acid dihydrazide, 4 parts of 10% aqueous solution of dioctylsulfosuccinic acid sodium salt (trade name: SN Wet OT-70, manufactured by San Nopco Co., Ltd.) with uniform mixing and thermal coloring A layer coating solution was obtained.

-Preparation of multicolor thermosensitive recording material In the preparation of the multicolor thermosensitive recording material of Example 1, the above-described thermosensitive coloring layer coating solution was used instead of the first thermosensitive coloring layer coating solution and the second thermosensitive coloring layer coating solution. A multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that the coating amount after use was changed to 5 g / m ² .

Comparative Example 2
A multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that in the preparation of the coating solution for the second thermosensitive coloring layer of Example 1, 8 parts of C liquid was not added and 48 parts of D liquid was added.

Comparative Example 3
A multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that in the preparation of the coating solution for the second thermosensitive coloring layer of Example 1, 40 parts of D solution was not added and 48 parts of C solution was used.

Comparative Example 4
A multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that 40 parts of E solution was added instead of 40 parts of D solution in the preparation of the second thermosensitive coloring layer coating solution of Example 1.

Comparative Example 5
A multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that 30 parts of K solution was not added in the preparation of the second thermosensitive coloring layer coating solution of Example 1.

  The obtained multicolor thermosensitive recording material was subjected to the following evaluation tests, and the results are shown in Table 1.

・ Color density Using a printer (model name: Barrabe 300, manufactured by Sato Co., Ltd.), applied energy: 0.15 mJ / dot for low temperature color development (red printing), and 0.27 mJ / dot for high temperature color development (black printing) ) The printing density at that time was measured using a Macbeth densitometer (RD-914 type, manufactured by Macbeth Co.). At this time, a magenta filter was used for red printing, and a cyan filter was used for black printing.

-Color tone The sample printed with two colors as described above was visually evaluated according to the following evaluation criteria.
(Low temperature coloring part)
A: Red color development, which is a low-temperature color development part, has no mixing of high-temperature color development color tone, and is particularly excellent in two-color separation and a red color close to a clear vermilion.
○: The red color development, which is a low-temperature color development part, has some turbidity due to high-temperature color development color tone and a mixture of purple-type color tone, but the vividness of red color development close to vermilion is maintained.
Δ: The red color development, which is the low temperature color development portion, shows turbidity due to the high temperature color tone and a mixture of purple color tone, but it is at a level that causes no practical problems.
X: Red color development, which is a low-temperature color development portion, has a significant turbidity due to high-temperature color development color tone, and two-color separation is not achieved, or there is a mixture of purple color tones, which is a practically problematic level.
(High temperature coloring part)
A: Black color tone, which is a high-temperature color tone, has almost no turbidity due to other hues, and has a black color with a stronger blackness.
○: The black color tone, which is a high-temperature color tone, has some turbidity due to other hues, but the black color is strongly black.
Δ: The black color tone, which is a high-temperature color tone, has turbidity due to other hues, but is at a level that causes no problem in practice.
X: Turbidity due to other hues is remarkable in the black color tone which is a high-temperature color tone, and there is a problem in practical use.

Light resistance Xenon weather meter (Model: XL-75, manufactured by Suga Test Instruments Co., Ltd.) (Conditions: Black panel temperature 63 ° C, chamber humidity 40% RH, 390 W / m ² ) After leaving the high-temperature color recording part for 12 hours, the density of the recording part was measured using a Macbeth densitometer (RD-914 type, manufactured by Macbeth Co.). At this time, a magenta filter was used for red printing, and a cyan filter was used for black printing.

・ Plasticizer resistance A low temperature of the above printing test in which a vinyl chloride wrap film (High Wrap SAS, manufactured by Mitsui Chemicals Platec Co., Ltd.) is wrapped three times on a polypropylene pipe (40 mm diameter pipe) and then immersed in tap water for 5 seconds. Place the color development section and the high temperature color development recording section on the low temperature color development recording section and the high temperature color development recording section of the printing test so that the recording surface is outside, and further wrap the vinyl chloride wrap film in three layers on it. After standing for 24 hours, the density of the recording part was measured using a Macbeth densitometer (RD-914 type, manufactured by Macbeth Co.). At this time, a magenta filter was used for red printing, and a cyan filter was used for black printing.

・ Heat and heat resistance (background fogging)
The white paper was left in a constant temperature and humidity chamber at 40 ° C. and 90% RH for 72 hours, and after the test, the background density was measured with a Macbeth densitometer (RD-914 type, manufactured by Macbeth) using a magenta filter.

Claims (12)

A first thermosensitive coloring layer containing a black color developing dye precursor and a color developer is provided on the support, and a dye precursor and developing color developing in a color tone different from black coloring is further formed on the first thermosensitive coloring layer. In a multicolor thermosensitive recording material provided with a second thermosensitive coloring layer containing a colorant, 3,3-bis (1-butyl-2-methylindole-3) is used as the dye precursor in the second thermosensitive coloring layer. -Yl) phthalide and 3-diethylamino-7-chlorofluorane, and in the second thermosensitive coloring layer, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2 At least one selected from '-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole and 2- (2'-hydroxy-5'-tert-octylphenyl) benzotriazole; And 2.5 parts by mass or more of 3-diethylamino-7-chlorofluorane with respect to 1 part by mass of the 3,3-bis (1-butyl-2-methylindol-3-yl) phthalide. A multicolor heat-sensitive recording material comprising not more than part by mass . 2. The multicolor thermosensitive recording material according to claim 1, wherein the ultraviolet absorber is contained in an amount of 5 to 35 mass% with respect to the total solid content of the second thermosensitive coloring layer. The multicolor thermosensitive recording material according to claim 1 or 2, wherein the melting point of the dye precursor that develops black color in the first thermosensitive coloring layer is 200 ° C or higher. Dye precursor to black color of the first thermosensitive coloring layer, 3- (N-ethyl--p- toluidino) -6-methyl-7-anilinofluoran, in any one of claims 1 to 3 The multicolor thermosensitive recording material described. Second thermosensitive coloring layer, the total amount of 100 parts by mass of the dye precursor which develops different color tones and black color, hydroxypropylmethylcellulose containing 10 to 30 parts by weight, any of claims 1-4 one The multicolor thermosensitive recording material according to Item. The second thermosensitive coloring layer contains 5 to 70 parts by mass of a hindered amine compound with respect to 100 parts by mass of the total amount of the dye precursor that develops a color tone different from that of black coloring. The multicolor thermosensitive recording material according to Item. The multicolor thermosensitive recording material according to any one of claims 1 to 6 , wherein the first thermosensitive coloring layer contains spherical plastic resin particles and / or hollow plastic resin particles. The multicolor thermosensitive recording material according to any one of claims 1 to 7 , wherein the first thermosensitive coloring layer contains at least one diphenylsulfone crosslinking compound represented by the following general formula (1).

(Where n represents an integer of 1 to 7) The main developers of the first thermosensitive coloring layer and the second thermosensitive coloring layer are the same compound, and the developer is Np-toluenesulfonyl-N′-3- (p-toluenesulfonyloxy). It is at least one selected from phenylurea, 4-hydroxy-4′-isopropoxydiphenylsulfone, 3,3′-diallyl-4,4′-dihydroxydiphenylsulfone, and 4-hydroxy-4′-allyloxydiphenylsulfone The multicolor thermosensitive recording material according to any one of claims 1 to 8 . Second thermosensitive coloring layer contains further at least one or more organic polymers selected from polyurea and polyurea over polyurethane, composite particles consisting of a dye precursor to black color, any one of the claims 1-9 The multicolor thermosensitive recording material according to Item. The multicolor thermosensitive recording material according to any one of claims 1 to 10 , wherein the first thermosensitive coloring layer and the second thermosensitive coloring layer are each formed by coating by a curtain coating method. The multicolor thermosensitive recording material according to any one of claims 1 to 11 , wherein the first thermosensitive coloring layer and the second thermosensitive coloring layer are applied and formed by a simultaneous multilayer curtain coating method.