JP5304512B2 - Multicolor thermal recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-color thermal recording material which shows sufficient color developing density and color separation properties, further, is excellent in shelf stability at a printing part and a texture part after long-term light resistance and heat/humidity resistance tests. <P>SOLUTION: This multi-color thermal recording material is composed of a first thermal color developing layer containing a black color developing dye precursor and a developer formed on a support, and a second thermal color developing layer containing a dye precursor which develops a color in a different color tone from the developed black color and a developer, formed on the first thermal color developing layer. Further, the recording material is characteristic in that the first thermal color developing layer contains an inorganic layer-like compound. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a multicolor thermosensitive recording material excellent in sufficient color density and color separability, and further excellent in storage stability of a printed part and a background part after a long period of light resistance and a heat and humidity test.

  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, in particular, a red-black two-color thermal 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 a color tone different from other parts. However, the red and black two-color heat-sensitive recording materials proposed so far do not always satisfy the requirements of both recording sensitivity and color separation, and printing and blank paper storage (heat resistance, moisture resistance, light resistance). It was. In particular, a heat-sensitive recording material that develops a vivid red color such as vermilion is generally desired as a red color tone. However, in the field of conventional thermal recording, many of these brilliant vermilion red colors are exhibited. There was no color thermosensitive recording material.

  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. 1, 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). It is disclosed. 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. Further, the dye precursor is covered with a color developing layer polymerized with a compound having an unsaturated carbon bond, and a specific red color forming dye precursor and a specific color developing layer not having a color adjusting layer on the surface in the heat-sensitive recording layer. A method of containing an electron accepting developer has been 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).

  It is necessary to add a large amount of a decoloring agent to the decoloring type multicolor thermosensitive recording material in order to obtain a sufficient decoloring effect for the low temperature coloring layer. Due to the action of the decoloring agent added in a large amount, the recorded image fades during long-term storage, or an extra amount of heat is required to melt the decoloring agent, which causes an excessive burden on the thermal head. However, 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 multi-layer structure is a method of obtaining two distinct colors by laminating two color-developing layers that produce different colors and applying different amounts of heat. Since the upper color-developing layer develops color at low temperature and the upper and lower color-development layers develop color at high temperature, and a mixed tone image of both colors is obtained, it is suitable when the lower color-developing layer is a black color developing system. The additive color type multi-color heat-sensitive recording material does not use a decoloring agent, so that it has an advantage of being excellent in long-term storage stability of a recorded image and can be produced at a relatively low cost, and an extra amount for melting the decoloring agent. Since no heat is required, there is an advantage that a high-temperature coloring layer can be colored with low energy compared to the decoloring type. However, the color-added multicolor heat-sensitive recording material has a problem in that if the amount of heat is excessively applied during low-temperature color development, a part of the high-temperature color-development layer also develops color mixing, making 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 diameters in the same color developing layer has been described, but there is still 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 by 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 development without a color control layer on the surface in the thermal recording layer In the method in which two kinds of neutral dye precursors and a specific electron-accepting color developer are included, although a red color tone close to vermilion is obtained, the color separation property is still insufficient due to the single layer structure. There is a drawback that background fogging occurs due to the melting point drop due to the combined use of two red coloring dye precursors.

  On the other hand, in order to improve the plasticizer resistance, light resistance and print image quality, and to obtain a recording material with high glossiness, a method using an inorganic layered compound in any layer is disclosed. For example, a method of adding mica to the undercoat layer (see Patent Document 18), a method of adding mica to the intermediate layer (see Patent Documents 19 and 20), and a method of adding mica to any layer constituting the heat-sensitive recording material (See Patent Document 21) and the like have been proposed. However, in the method described in Patent Document 18, the coating liquid for the undercoat layer is thickened, and the adhesion to the support is deteriorated. In addition, the method described in Patent Documents 19, 20, and 21 is effective to some extent. However, there are drawbacks such as reduced surface strength, poor printability and reduced recording sensitivity, and the effect of improving light resistance is insufficient.

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 Japanese Patent Laid-Open No. 11-5366 JP 10-193789 A JP 2004-216718 A JP 2001-199163 A

  An object of the present invention is to provide a multicolor thermosensitive recording material having a sufficient color density and color separability, long-time light resistance, and excellent storage stability of a printed portion and a background portion after a heat and humidity test.

  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 material 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, an inorganic layered compound is contained in the first thermosensitive coloring layer, The inventors have found that the above problems can be solved and have completed the present invention.

  That is, the present invention provides the following heat-sensitive 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. A multicolor thermosensitive recording material provided with a second thermosensitive coloring layer containing a body and a developer, wherein the first thermosensitive coloring layer contains an inorganic layered compound.
Item 2: The multicolor thermosensitive recording material according to Item 1, wherein the inorganic layered compound is water-swellable mica.
Item 3: The multicolor thermosensitive recording material according to Item 1 or 2, wherein 2- (2'-hydroxy-5'-methylphenyl) benzotriazole is contained as an ultraviolet absorber only in the second thermosensitive coloring layer.
Item 4: Any one of Items 1 to 3, wherein the dye precursor that develops a black color in the first thermosensitive coloring layer is 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane The multicolor thermosensitive recording material according to item 1.
Item 5: The multicolor thermosensitive recording material according to any one of Items 1 to 4, wherein the first thermosensitive coloring layer contains spherical plastic resin particles or hollow plastic resin particles.
Item 6: 3,3-bis (1-butyl-2-methylindole-), a red coloring dye precursor, as a dye precursor that develops a color tone different from that of black coloring in the second thermosensitive coloring layer Item 6. The multicolor thermosensitive recording material according to any one of Items 1 to 5, comprising 3-yl) phthalide.
Item 7: The main color developers of the first thermosensitive coloring layer and the second thermosensitive coloring layer are the same compound, and the compound is Np-toluenesulfonyl-N′-3- (p-toluenesulfonyl). At least one selected from oxy) phenylurea, 4-hydroxy-4′-isopropoxydiphenylsulfone, 3,3′-diallyl-4,4′-dihydroxydiphenylsulfone, and 4-hydroxy-4′-allyloxydiphenylsulfone. Item 7. The multicolor thermosensitive recording material according to any one of Items 1 to 6, which is a seed or more.
Item 8: Any one of Items 1 to 7, 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. 2. The multicolor thermosensitive recording material according to item 1.
Item 9: The multicolor thermosensitive recording material according to any one of Items 1 to 8, wherein the first thermosensitive coloring layer and the second thermosensitive coloring layer are each formed by coating and drying by a curtain coating method.
Item 10: The multicolor thermosensitive recording material according to any one of Items 1 to 8, wherein the first thermosensitive coloring layer and the second thermosensitive coloring layer are formed by coating and drying by a simultaneous multilayer curtain coating method.

  According to the present invention, it is possible to provide a multicolor thermosensitive recording material excellent in sufficient color density and color separation property, long-time light resistance, and storage stability of a printed portion and a background portion after a heat and humidity test.

  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 material provided with a second thermosensitive coloring layer containing a precursor and a developer, the first thermosensitive coloring layer contains an inorganic layered compound, and if necessary, in other thermosensitive recording paper fields A heat-sensitive color forming layer containing a conventionally known adhesive, white pigment, preservability improver and the like is formed on a support.

The inorganic layered compound used in the present invention has a general formula: A (B, C) _2-5 D ₄ O ₁₀ (OH, F, O) ₂ [where A is any one of K, Na, and Ca, B and C are any one of Fe (II), Fe (III), Mn, Al, Mg, and V, and D is Si or Al], a mica group represented by the general formula: 3MgO · 4SiO · H Talc represented by ₂ O, general formula; (H ₂ O) ₄ (OH) ₄ Mg ₈ Si ₁₂ O ₃₀ · 6-8H ₂ O, sepiolite, teniolite, montmorillonite, saponite, hectorite, sodium hector Light, zirconium phosphate, etc. are mentioned.

In the mica group, examples of natural mica include muscovite, soda mica, phlogopite, biotite and sericite. Further, as the synthetic mica, non-swelling mica such as fluor-phlogopite mica KMg ₃ (AlSi ₃ O ₁₀ ) F ₂ , potassium tetrasilicon mica KMg _2.5 (Si ₄ O ₁₀ ) F ₂ , and Na tetrasilic mica NaMg _2.5 (Si ₄ O ₁₀ ) F ₂ , Na or Li Teniolite (Na, Li) Mg ₂ Li (Si ₄ O ₁₀ ) F ₂ , Montmorillonite Na or Li Hectorite (Na, Li) _1/8 Mg _2/5 Li _1/8 (Si ₄ O ₁₀ ) F ₂ , water-swelling mica such as sodium tetrasilicon mica and the like can be mentioned. In addition, synthetic smectites are also useful.

  In the present invention, among the above inorganic layered compounds, fluorine-based water-swellable mica, which is a synthetic inorganic layered compound, is particularly useful.

  The aspect ratio of the inorganic layered compound is preferably 20 or more, more preferably 100 or more, and particularly preferably 200 or more. The aspect ratio is the ratio of the thickness of the inorganic layered compound to the diameter of the particles.

  The average particle diameter of the inorganic layered compound is preferably about 0.3 to 20 μm, more preferably about 0.5 to 10 μm, and particularly preferably about 1 to 5 μm. The average thickness of the inorganic layered compound is preferably 0.1 μm or less, more preferably 0.05 μm or less, and particularly preferably 0.01 μm or less.

  The content of the inorganic stratiform compound is about 0.1 to 8% by mass, more preferably about 0.5 to 6% by mass, based on the total solid content of the thermosensitive coloring layer. When the content is less than 0.1% by mass, the effect of the present invention is not sufficient. On the other hand, when the content exceeds 8% by mass, the viscosity of the coating liquid becomes too high, and the recording sensitivity and the coating strength decrease.

  According to the present invention, the first thermosensitive coloring layer and the second thermosensitive layer can be formed by containing a specific inorganic layered compound in the first thermosensitive coloring layer, so that a uniform, dense and highly smooth layer can be formed. Interlayer separation of the color developing layer is improved, and sufficient color density and color separation can be obtained. Furthermore, since the interlayer separation is improved and the function of each thermosensitive coloring layer is sufficiently exhibited, the storage stability of the background portion and the printed portion after a long-time light resistance and heat and humidity test is also improved.

  In the present invention, various known dye precursors for black color development in the first thermosensitive coloring layer can be used, and 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) arinino-5,7-dimethylfluorane, etc. However, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane is more preferred because of its high sensitivity and excellent 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. In addition to the black coloring system, a blue coloring system, a green coloring system, a yellow coloring system, and a red coloring system dye precursor may be added 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 first thermosensitive coloring layer.

  Further, 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 tone different from black is improved, and is different from black. It has become possible to greatly improve the storage stability of colors that develop in color tone, especially the chemical resistance of 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 recording sensitivity and image quality. The content of the plastic resin particles used in the present invention is about 5 to 30% by mass, preferably about 10 to 20% by mass of the total solid content of the first thermosensitive coloring layer, and the content is less than 5% by mass. However, the effect of improving the chemical resistance 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 preferable that the first thermosensitive coloring layer contains at least one diphenylsulfone crosslinking compound represented by the following general formula (1).

（但し、ｎは１〜７の整数を表わす）

(Where n represents an integer of 1 to 7)

  Although it does not specifically limit as content of the said diphenyl sulfone bridge | crosslinking type compound used in a 1st thermosensitive coloring layer, About 100-1000 mass parts with respect to a total of 100 mass parts of a dye precursor, Preferably it is 100-500 masses. 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 composite particles in the second thermosensitive coloring layer Can be improved.

  In the present invention, various known compounds can be used as the color developer used in the first thermosensitive coloring layer and the second thermosensitive coloring 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, 4-hydroxy -4'-allyloxydiph Phenolic compounds such as nylsulfone, 3,3′-diallyl-4,4′-dihydroxydiphenylsulfone, butyl bis (p-hydroxyphenyl) acetate and methyl bis (p-hydroxyphenyl) acetate, 4-hydroxybenzophenone, 4 -Dimethyl hydroxyphthalate, methyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate, 4-hydroxybenzoate-sec-butyl, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, tolyl 4-hydroxybenzoate Phenolic compounds such as 4-hydroxybenzoic acid chlorophenyl, 4,4′-dihydroxydiphenyl ether, or benzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, salicylic acid, 3-tert-butylsalicy Acids, 3-isopropylsalicylic acid, 3-benzylsalicylic acid, 3- (α-methylbenzyl) salicylic acid, 3,5-di-tert-butylsalicylic acid and other aromatic carboxylic acids, and these phenolic compounds, aromatic carboxylic acids and For example, organic acidic substances such as salts with polyvalent metals such as zinc, magnesium, aluminum and calcium, Np-toluenesulfonyl-N′-3- (p-toluenesulfonyloxy) phenylurea, N- (p-toluene) And urea compounds such as sulfonyl) -N ′-(p-butoxycarboyl) urea and Np-tolylsulfonyl-N′-phenylurea.

  Among these developers, Np-toluenesulfonyl-N′-3- (p) is used for the first thermosensitive coloring layer from the viewpoint of chemical resistance, recording sensitivity, and heat resistance during high-temperature storage (background fogging). -Toluenesulfonyloxy) phenylurea, 4-hydroxy-4'-isopropoxydiphenylsulfone, 3,3'-diallyl-4,4'-dihydroxydiphenylsulfone, and 4-hydroxy-4'-allyloxydiphenylsulfone It is preferable to use at least one kind of compound, and 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 ′ It is preferred to use at least one or more compounds selected from dihydroxydiphenyl sulfone, and 4-hydroxy-4'-allyloxy diphenyl sulfone. Furthermore, it is preferable that the first and second heat-sensitive color developing layers are the same compound from the viewpoint of background fogging. Furthermore, among these, it is particularly preferable to use Np-toluenesulfonyl-N′-3- (p-toluenesulfonyloxy) phenylurea as a color developer for the first thermosensitive coloring layer and the second thermosensitive coloring layer. It is preferable in terms of chemical properties.

  The amount of the developer used in the first thermosensitive coloring layer and the second thermosensitive coloring layer is preferably used in an amount of about 100 to 1000 parts by mass with respect to a total of 100 parts by mass of the dye precursor. More 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 formula (1) of the present invention is arbitrary, but the diphenylsulfone crosslinkable compound represented by the formula (1) is based on 100 parts by mass of the developer. In particular, it is particularly preferably about 1 to 90% by mass, specifically about 5 to 80% by mass.

  In the present invention, it is preferable to contain 2- (2'-hydroxy-5'-methylphenyl) benzotriazole as an ultraviolet absorber only in the second thermosensitive coloring layer in order to further improve light resistance. When 2- (2'-hydroxy-5'-methylphenyl) benzotriazole is contained in the first thermosensitive coloring layer, the melting point is lower and the color separation property is deteriorated.

  In the present invention, the second thermosensitive coloring layer may contain about 10 to 30 parts by mass of hydroxypropyl methylcellulose with respect to 100 parts by mass of the dye precursor that develops a color tone different from that of black coloring. This is preferable because it suppresses background fogging. 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 a dye precursor that develops a color tone different from that of black coloring. It is preferable for suppressing fog. The hindered amine compound added to the second thermosensitive coloring layer is a compound represented by the following [Chemical Formula 2], a compound represented by [Chemical Formula 3] having a molecular weight of 2500 or more, and a molecular weight represented by [Chemical Formula 4] 2000. The above compounds, and further, compounds represented by [Chemical Formula 5] to [Chemical Formula 10] and the like can be used as commercial products.

  The present invention provides a first thermosensitive color-developing layer containing a black color-forming dye precursor and a developer on a support, and further a dye that develops a color tone different from black color development on the first thermosensitive color-developing layer. A multicolor thermosensitive recording material provided with a second thermosensitive coloring layer containing a precursor and a developer, wherein the first thermosensitive coloring layer contains an inorganic layered compound. However, as a dye precursor that develops a color tone different from that of black in the second thermosensitive coloring layer, 3,3-bis (1-butyl-2-methylindole-3- Yl) phthalide is preferable from the viewpoint of storage stability of red color development, particularly light resistance. Moreover, as long as the effects of the present invention are not impaired, other red coloring dye precursors may be used in combination, such as 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-chloro. Red color-forming dye precursors such as fluorane, 3-diethylamino-7-methylfluorane, and 3-N-ethyl-Np-methylphenylamino-7-chlorofluorane are red near vermilion, Although particularly preferred, 3-diethylamino-7-chlorofluorane is particularly preferred from the viewpoints of background fogging, red color preservation, particularly light resistance. When 3,3-bis (1-butyl-2-methylindole-3-yl) phthalide and 3-diethylamino-7-chlorofluorane are used in combination, 3,3-bis (1-butyl-2-methylindole) It is preferable that 3-diethylamino-7-chlorofluorane is less than 7.5 mass parts with respect to 1 mass part of -3-yl) phthalide. When the addition amount of 3-diethylamino-7-chlorofluorane is 7.5 parts by mass or more, the storage stability of red color, particularly the light resistance, is significantly deteriorated.

In the present invention, from the viewpoint of adjusting the color tone of black color development and storage stability, the second thermosensitive color development layer further contains at least one organic polymer selected from polyurea and polyurea-polyurethane and a dye precursor that produces black color development. It is preferable to use composite particles consisting of 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 of the composite particles contained in the second thermosensitive coloring layer include 3-di (n-pentyl) amino-6-methyl-7-anilinofluorane and 3-di (n-butylamino). -7- (2-chloroanilino) fluorane, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (3-toluidino) fluorane, etc. It is more preferable in terms of being less likely to cause 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. Phenyl) -4-azaphthalide, dyes such as 3- [2,2-bis (1-ethyl-2-methylindol-3-yl) vinyl] -3- (4-diethylaminophenyl) phthalide, recorded if necessary An aromatic organic compound (sensitizer) having a melting point of about 40 to 150 ° C., an ultraviolet absorber, an antioxidant, an oil-soluble fluorescent dye, a release agent, etc. are added to increase light resistance in order to increase sensitivity. It may be.

  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 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane and 1,1,3-tris (2-methyl-4-hydroxy-). 5-tert-butylphenyl) butane, 1,1-bis (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 4,4 ′-[1,4-phenylenebis (1-methylethylidene) ] Phenolic compounds such as bisphenol and 4,4 '-[1,3-phenylenebis (1-methylethylidene)] bisphenol, 4-benzyloxyphenyl-4'-(2-methyl-2,3-epoxy Propyloxy) phenylsulfone, 4- (2-methyl-1,2-epoxyethyl) diphenylsulfone, and 4- (2-ethyl-1,2-epoxy) One or more compounds selected from epoxy compounds such as til) diphenylsulfone and isocyanuric acid compounds such as 1,3,5-tris (2,6-dimethylbenzyl-3-hydroxy-4-tert-butyl) isocyanuric acid Can be used. Of course, the image stabilizer is not limited to these, and two or more kinds of compounds may be used in combination as required.

  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. . In the present invention, various known adhesives are used as the adhesive constituting the thermosensitive coloring layer. For example, starches such as oxidized starch, acid-modified starch, phosphate-modified starch, enzyme-modified starch, cation-modified starch, esterified starch, etherified starch and vinyl acetate-modified grafted starch, polyvinyl alcohol and its derivatives, methylcellulose, Cellulose derivatives such as ethylcellulose, carboxymethylcellulose, methoxycellulose, hydroxyethylcellulose and hydroxypropylmethylcellulose, polyacrylic acid soda, polyacrylamide, polyvinylpyrrolidone, acrylic acid amide / acrylic acid ester copolymer, acrylic acid amide / acrylic acid ester / methacrylic acid Acid copolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, sodium alginate, gelatin, casein, etc. But are below their content must not exceed the content of the polymerization degree of 500 or more polyvinyl alcohol. In addition to water-soluble adhesives, polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylic ester, polybutyl methacrylate, styrene / butadiene copolymer, vinyl chloride / vinyl acetate copolymer, ethylene / vinyl acetate copolymer Further, latex such as styrene / butadiene / acrylic copolymer can be used.

  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, dimethylolurea compounds, aziridine compounds, blocked isocyanate compounds, carboxylic acid dihydrazide compounds, ammonium persulfate and ammonium chloride An inorganic compound such as diiron, magnesium chloride, sodium tetraborate, potassium tetraborate, or at least one crosslinkable compound selected from boric acid, boric acid triester, boron-based polymer, etc. with respect to the total solid content of the thermosensitive coloring layer 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 heat-sensitive color developing 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 dye precursor 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. Of water-soluble synthetic polymer compounds such as polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, modified polyvinyl alcohol such as sulfone-modified polyvinyl alcohol, methylcellulose, carboxymethylcellulose, hydroxypropylmethylcellulose, styrene-maleic anhydride copolymer salts and derivatives thereof In addition, 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.

  Furthermore, a sensitizer can be used in combination according to the purpose. Specific examples of the sensitizer include stearic acid amide, methoxycarbonyl-N-stearic acid benzamide, N-benzoyl stearic acid amide, N-eicosanoic acid amide, ethylene bistearic acid amide, behenic acid amide, and methylenebisstearic acid. Amide, N-methylol stearic acid amide, dibenzyl terephthalate, dimethyl terephthalate, dioctyl terephthalate, benzyl p-benzyloxybenzoate, phenyl 1-hydroxy-2-naphthoate, 2-naphthylbenzyl ether, m-terphenyl, Oxalic acid dibenzyl ester, oxalic acid-di-p-methylbenzyl ester, oxalic acid-di-p-chlorobenzyl ester, p-benzylbiphenyl, tolylbiphenyl 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, etc. . In particular, when a mixed dispersion of oxalic acid di-p-methylbenzyl ester and oxalic acid di-p-chlorobenzyl ester is 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.

  In the present invention, as a method for forming each thermosensitive recording 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. In addition, although it is possible to apply each of the thermosensitive coloring layers alone or simultaneously, the first thermosensitive coloring layer and the second thermosensitive coloring layer can be further reduced in 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, a heat-sensitive recording layer formed by curtain coating can obtain better color separation and good image quality, and also improve image storage stability.

  When the thermosensitive coloring layer is formed by a 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, the surface tension is not sufficiently low, and the curtain film is easily cut off. 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 coloring layer can be divided into three or more layers as required, 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 thermal recording media 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.

  When the protective layer is formed by a curtain coating method, a surfactant is added to the protective layer coating solution 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. As addition amount of surfactant, it is preferable that it is about 0.05-3.0 mass% with respect to the total solid of a protective layer. If it is less than 0.05% by mass, the effect of addition is small, the surface tension is not sufficiently low, and the curtain film is easily cut off. 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 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 for the undercoat layer is determined in consideration of the coating strength and the recording sensitivity of the thermosensitive coloring layer, but is preferably about 3 to 100% by mass with respect 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 heat-sensitive recording material, it can be further processed to obtain a heat-sensitive recording material having 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 material 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 with an oil absorption of 110 ml / 100 g, 80 parts of plastic hollow particle emulsion (trade name: AE852, solid content concentration 26%, hollow rate 80%, average particle size 1.0 μm, manufactured by JSR), solid as an adhesive 20 parts of 50% styrene / butadiene / acrylonitrile copolymer latex, 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, Oji) An undercoat layer coating solution was obtained by uniformly mixing and stirring 25 parts of a 20% aqueous solution of Cornstarch Co., Ltd. and 90 parts of water.

(Preparation of undercoat layer)
On one surface of woodfree paper having a basis weight of 60 g / m ^2, coated with a subbing layer coating solution in a blade coater as the coating amount after drying of 7 g / m ^2, to obtain an undercoat layer-coated base paper and dried .

(Preparation of coating solution for thermosensitive coloring layer)
-Preparation of dye precursor dispersion (liquid A) 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane, sulfone-modified polyvinyl (Goceran L-3266: Nippon Synthetic Chemical) A composition comprising 10 parts of a 20% aqueous solution (made by Kogyo) and 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 diameter was 0.8 μm. did.

Preparation of dye precursor dispersion (liquid B) 20 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, sulfone-modified polyvinyl (Goselan L-3266: manufactured by Nippon Synthetic Chemical Industry) The composition comprising 10 parts of a 20% aqueous solution and 20 parts of water was pulverized and dispersed using a vertical sand mill (Sand Grinder, manufactured by AIMEX Co., Ltd.) so that the average particle size 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.) using a vertical sand mill (a sand grinder manufactured by IMEX Co., Ltd.), a composition comprising 10 parts of a 20% aqueous solution and 20 parts of water so that the average particle size is 0.7 μm. Crushed and dispersed.

-Preparation of dye precursor dispersion (liquid D) 3-diethylamino-7-chlorofluorane 20 parts, sulfone-modified polyvinyl (trade name: Gocelan L-3266, manufactured by Nippon Synthetic Chemical Industry) 10 parts of an aqueous solution, And the composition which consists of 20 parts of water was grind | pulverized and disperse | distributed so that the average particle diameter might be set to 0.7 micrometer using the vertical sand mill (The product made from IMEX Co., Ltd., a sand grinder).

Preparation of dye precursor-containing composite particle dispersion (liquid E) 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 rotational speed of 8000 rpm using a homogenizer, and then 60 parts of water was added to the emulsified dispersion for homogenization. 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 concentration was 20%, and the dye precursor-containing composite having an average particle diameter of 0.8 μm. A particle dispersion was obtained.

-Preparation of developer dispersion (liquid F) Np-toluenesulfonyl-N'-3- (p-toluenesulfonyloxy) phenylurea 20 parts, sulfone-modified polyvinyl (trade name: Goceran L-3266, Japan A composition consisting of 10 parts of a 20% aqueous solution (manufactured by Synthetic Chemical Industry Co., Ltd.) and 20 parts of water is pulverized using a vertical sand mill (made by Imex Corp., sand grinder) so that the average particle diameter is 1.2 μm. Distributed.

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

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

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

-Preparation of UV absorber dispersion (liquid J) 2- (2'-hydroxy-5'-methylphenyl) benzotriazole (trade name: JF77T, manufactured by Johoku Chemical Co., Ltd.), sulfone-modified polyvinyl (trade name: A composition comprising 10 parts of a 20% aqueous solution of Gocelan L-3266 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and 20 parts of water is used with a vertical sand mill (manufactured by IMEX Co., Ltd., sand grinder), and the average particle size is 1. It was pulverized and dispersed so as to be 0.0 μm.

Preparation of UV absorber dispersion (liquid K) 2- (2′-hydroxy-3′-t-butyl-5′-methylphenyl) -5-chlorobenzotriazole (trade name: JF79, manufactured by Johoku Chemical Co., Ltd.) A composition composed of 20 parts, 10 parts of a 20% aqueous solution of sulfone-modified polyvinyl (trade name: Goseilan L-3266, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), and 20 parts of water is used as a vertical sand mill (made by Imex Corporation, Sand Using a grinder), the mixture was pulverized and dispersed so that the average particle size was 1.0 μm.

-Preparation of diphenylsulfone crosslinkable compound dispersion (L liquid) The 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 Co., Ltd. 20 parts, 20 parts of a 20% aqueous solution of sulfonic acid-modified polyvinyl alcohol, and 20 parts of water using a vertical sand mill (Immex Co., Ltd., sand grinder), the average particle size is 1.0 μm. The mixture was pulverized and dispersed so that

-Preparation of coating liquid for first thermosensitive coloring layer A part 45 parts, F part 90 parts, L part 10 parts, mixed dispersion of oxalic acid di-p-methylbenzyl ester and oxalic acid di-p-chlorobenzyl ester ( Product name: HS-7150B, solid concentration 50%, manufactured by Dainippon Ink Co., Ltd.) 8 parts, plastic hollow particles (trade name: AE852, solid content concentration 26%, hollow rate 55%, manufactured by JSR) 50 parts, diacetone 50 parts of a 15% aqueous solution of modified polyvinyl alcohol (trade name: DF-10, degree of polymerization 1000, manufactured by Nihon Ventures and Poval), SBR latex (trade name: L-1571, solid content concentration 48%, manufactured by Asahi Kasei Chemicals Corporation) ) 8 parts, 8 parts of 35% aqueous solution of adipic acid dihydrazide, 4 parts of 10% aqueous solution of dioctyl sulfosuccinic acid sodium salt (trade name: SN Wet OT-70, manufactured by San Nopco) 60 parts of 5% aqueous dispersion of sodium tetrasilicon mica (trade name: NTO-5, aspect ratio: 2000, average diameter: 13 μm, average thickness: 5 to 6 nm, manufactured by Topy Industries Co., Ltd.) was uniformly mixed and stirred. A coating solution for the first thermosensitive coloring layer was obtained.

-Preparation of coating solution for second thermosensitive coloring layer 48 parts C solution, 84 parts F solution, 30 parts J solution, mixed dispersion of oxalic acid di-p-methylbenzyl ester and oxalic acid di-p-chlorobenzyl ester ( Product name: HS-7150B, solid content concentration 50%, manufactured by Dainippon Ink Co., Ltd. 8 parts, 15% aqueous solution of diacetone modified polyvinyl alcohol (trade name: DF-10, degree of polymerization 1000, manufactured by NIPPON VICHI POVAL) 50 parts, 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%, manufactured by Asahi Kasei Chemicals), adipine 8 parts of 35% aqueous solution of acid dihydrazide, dioctylsulfosuccinate sodium salt (trade name: SN Wet OT-70, manufactured by San Nopco) Uniformly mixing and stirring the liquid 4 parts to obtain a second thermal color-forming layer coating solution.

-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 Acetate / Poval), zinc stearate (trade name: Hydrin Z-8-36, solid content concentration 36%, manufactured by Chukyo Yushi Co., Ltd.) 25 10 parts of a 35% aqueous solution of adipic acid dihydrazide and 20 parts of a 5% aqueous solution of dioctylsulfosuccinic acid sodium salt (trade name: SN Wet OT-70, manufactured by San Nopco) were mixed and stirred to obtain a coating solution for a protective layer. It was.

・ Preparation of multicolor thermosensitive recording material The first thermosensitive coloring layer coating solution, the second thermosensitive coloring layer coating solution, and the protective layer coating solution are each applied after drying on the base paper coated with the undercoat layer prepared above. a quantity by coating and drying at ^{4g / m 2, 3g / m} 2, and 2 g / ^{m 2} and composed as rod coating undercoat layer, the first thermosensitive coloring layer, a second thermosensitive coloring layer and a protective layer sequentially After obtaining the multicolor heat-sensitive recording material, the multicolor heat-sensitive recording material was prepared by using a super calendar so that the Beck smoothness (JIS-P8119) of the heat-sensitive recording surface was 4000 seconds.

Example 2
In the preparation of the coating solution for the first thermosensitive coloring layer of Example 1, sodium hectorite (trade name: trade name: instead of 60 parts of 5% aqueous dispersion of sodium tetrasilicon mica (trade name: NTO-5, supra). Multicolor thermosensitive in the same manner as in Example 1 except that 60 parts of a 5% aqueous dispersion of sol B2, aspect ratio: 1000, average diameter: 3 μm, average thickness: 3-4 nm, manufactured by Topy Industries, Ltd. A recording material was prepared.

Example 3
In the preparation of the coating solution for the first thermosensitive coloring layer of Example 1, instead of 60 parts of 5% aqueous dispersion of sodium tetrasilicon mica (trade name: NTO-5, supra), talc (trade name: PC talc) Multi-color heat sensitivity in the same manner as in Example 1 except that 10 parts of a 30% aqueous dispersion having an aspect ratio of 2 to 4, an average diameter of 2 μm, an average thickness of 1 to 2 μm, manufactured by Daio Engineering Co., Ltd. was used. A recording material was prepared.

Example 4
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 and 40 parts of D liquid were used instead of 48 parts of C liquid. Was made.

Example 5
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, 30 parts of K solution was used instead of 30 parts of J 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 first thermosensitive coloring layer coating liquid 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 first thermosensitive coloring layer of Example 1, instead of 50 parts of plastic hollow particles (trade name: AE852, solid content concentration 26%, hollow ratio 55%, manufactured by JSR), plastic solid particles A multicolor thermosensitive recording material was produced in the same manner as in Example 1 except that 25 parts (trade name: Grosdale 130S, solid concentration 53%, manufactured by Mitsui Chemicals, Inc.) were added.

Example 8
In the preparation of the first thermosensitive coloring layer coating liquid of Example 1, instead of 90 parts of the F liquid, 90 parts of the G liquid was used. Further, in the preparation of the second thermosensitive coloring layer coating liquid, instead of the F liquid of 84 parts. In addition, a multicolor thermosensitive recording material was produced in the same manner as in Example 1 except that the liquid G was 84 parts.

Example 9
In the preparation of the first thermosensitive coloring layer coating liquid of Example 1, 90 parts of H liquid was used instead of 90 parts of F liquid, and in addition, in the preparation of the second thermosensitive coloring layer coating liquid, instead of 84 parts of F liquid. A multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that 84 parts of the H liquid was used.

Example 10
In the preparation of the coating solution for the first thermosensitive coloring layer of Example 1, 90 parts of I solution was used instead of 90 parts of the F solution. Further, in the preparation of the coating solution for the second thermosensitive coloring layer, 84 parts of the F solution were substituted. In addition, a multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that the liquid I was 84 parts.

Example 11
A multicolor thermosensitive recording material was produced in the same manner as in Example 1 except that 30 parts of E solution was added in the preparation of the second thermosensitive coloring layer coating solution of Example 1.

Example 12
In the production of the multicolor thermosensitive recording material of Example 11, 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 11 except that sequential coating and drying were performed.

Example 13
In the production of the multicolor thermosensitive recording material of Example 11, 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 11 except that the multilayer coating and drying were performed.

Comparative Example 1
Instead of preparing the coating solution for the first thermosensitive coloring layer and the coating solution for the second thermosensitive coloring layer in Example 1, as the coating solution for the thermosensitive coloring layer, 5 parts of C solution, 25 parts of D solution, 70 parts of E solution, 90 parts of liquid F, diacetone-modified polyvinyl alcohol (trade name: DF-10, degree of polymerization 1000, manufactured by Nippon Bibi-Poval), hydroxypropyl methylcellulose (trade name: Metroles 60SH-03, Shin-Etsu Chemical) 20 parts of 15% aqueous solution, 8 parts of SBR latex (trade name: L-1571, solid concentration 48%, manufactured by Asahi Kasei Chemicals), 8 parts of 35% aqueous solution of adipic acid dihydrazide, dioctylsulfosuccinate sodium salt ( Product name: SN wet OT-70, 4 parts of 10% aqueous solution of San Nopco), 60 parts of 5% aqueous dispersion of sodium tetrasilicon mica (trade name: NTO-5, supra) After uniformly mixing and stirring to obtain a thermal coloring layer coating liquid, the coating amount after drying the thermal coloring layer coating liquid and the protective layer coating liquid on the base paper coated with the undercoat layer prepared above is After coating and drying by a rod coating method so as to be 5 g / m ² and 2 g / m ² , a multicolor thermosensitive recording material having an undercoat layer, a thermosensitive coloring layer and a protective layer in order is obtained, The recording surface was smoothed so as to have a Beck smoothness (JIS-P8119) of 4000 seconds to produce a multicolor thermosensitive recording material.

Comparative Example 2
Example 1 except that 60 parts of a 5% aqueous dispersion of sodium tetrasilicon mica (trade name: NTO-5, supra) was not added in the preparation of the first thermosensitive coloring layer coating liquid of Example 1. A multicolor thermal recording material was prepared in the same manner as described above.

Comparative Example 3
In the preparation of the first thermosensitive coloring layer coating liquid of Example 1, 60 parts of a 5% aqueous dispersion of sodium tetrasilicon mica (trade name: NTO-5, supra) was not added. A multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that 60 parts of a 5% aqueous dispersion of sodium tetrasilicon mica (trade name: NTO-5, supra) was added.

Comparative Example 4
In the preparation of the coating solution for the first thermosensitive coloring layer of Example 1, 60 parts of a 5% aqueous dispersion of sodium tetrasilicon mica (trade name: NTO-5, supra) was not added, but for the second thermosensitive coloring layer. A multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that 60 parts of a 5% aqueous dispersion of sodium tetrasilicon mica (trade name: NTO-5, supra) was added. .

Comparative Example 5
In the preparation of the coating solution for the first thermosensitive coloring layer of Example 1, 60 parts of a 5% aqueous dispersion of sodium tetrasilicon mica (trade name: NTO-5, supra) was not added. A multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that 60 parts of a 5% aqueous dispersion of sodium tetrasilicon mica (trade name: NTO-5, supra) was added.

  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)
(Double-circle): The 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 development 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 noticeable 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 and 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 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 blank paper part and the recording part was measured using a Macbeth densitometer (RD-914, manufactured by Macbeth Co.). At this time, a magenta filter was used for blank paper and red printing, and a cyan filter was used for black printing.

・ Heat and heat resistance The low temperature color recording part and the high temperature color recording part of the printing test are left for 72 hours in a constant temperature and humidity chamber of 40 ° C.-90% RH, and after the test, magenta is measured with a Macbeth densitometer (RD-914 type, manufactured by Macbeth Co. The density of the white paper portion and the recording portion was measured using a filter. At this time, a magenta filter was used for white paper and red printing, and a cyan filter was used for black printing.

  According to the present invention, a first thermosensitive color-developing layer containing a black dye-forming dye precursor and a developer is provided on a support, and further, the first thermosensitive color-developing layer has a color tone different from that of black color development. In a multicolor thermosensitive recording material provided with a second thermosensitive coloring layer containing a dye precursor and a developer, sufficient color density and color separation can be achieved by including an inorganic layered compound in the first thermosensitive coloring layer. And a multicolor thermosensitive recording material excellent in storage stability of a printed part and a background part after a long-time light resistance and heat and humidity test can be provided.

Claims (10)

  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. A multicolor thermosensitive recording material provided with a second thermosensitive coloring layer containing a colorant, wherein the first thermosensitive coloring layer contains an inorganic layered compound.   The multicolor thermosensitive recording material according to claim 1, wherein the inorganic layered compound is water-swellable mica.   3. The multicolor thermosensitive recording material according to claim 1, wherein 2- (2′-hydroxy-5′-methylphenyl) benzotriazole is contained as an ultraviolet absorber only in the second thermosensitive coloring layer.   The dye precursor that produces black color in the first thermosensitive coloring layer is 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane. The multicolor heat-sensitive recording material described in 1.   The multicolor thermosensitive recording material according to any one of claims 1 to 4, wherein the first thermosensitive coloring layer contains spherical plastic resin particles or hollow plastic resin particles.   In the second thermosensitive coloring layer, 3,3-bis (1-butyl-2-methylindol-3-yl), which is a red coloring dye precursor, is used as a dye precursor that develops a color tone different from that of black coloring. The multicolor thermosensitive recording material according to any one of claims 1 to 5, which contains a phthalide.   The main color developers in the first thermosensitive color developing layer and the second thermosensitive color developing layer are the same compound, and the compound is Np-toluenesulfonyl-N′-3- (p-toluenesulfonyloxy). 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 6.   8. The composite particle comprising at least one organic polymer selected from polyurea and polyurea-polyurethane and a dye precursor that develops black color is further contained in the second thermosensitive coloring layer. The multicolor thermosensitive recording material according to Item.   The multicolor thermosensitive recording material according to any one of claims 1 to 8, wherein the first thermosensitive coloring layer and the second thermosensitive coloring layer are each formed by coating and drying by a curtain coating method.   The multicolor thermosensitive recording material according to any one of claims 1 to 8, wherein the first thermosensitive coloring layer and the second thermosensitive coloring layer are formed by coating and drying by a simultaneous multilayer curtain coating method.