JP4882785B2 - Multicolor thermal recording material and method for producing the same - Google Patents

Description

  The present invention relates to a multicolor heat-sensitive recording material that develops colors different from each other due to differences in heating application conditions from a thermal head, and a method for producing the same. More specifically, the present invention relates to a multicolor thermosensitive recording medium capable of detecting a coating defect in an upper thermosensitive coloring layer in a two-color thermosensitive coloring layer and a coating defect portion. The present invention relates to a method for producing a multicolor thermal recording medium to be excluded.

  Conventionally, a thermal recording medium that utilizes a color development reaction between a dye precursor and a color developer that is brought into contact with color by heating and melts and contacts both color developing materials by heating to obtain a color image. Widely known. Such a thermal recording medium is relatively inexpensive, has a compact recording device, and is easy to maintain, so it can be used in a wide range of recording media for facsimiles, word processors, various computers, and other applications. Has been.

  The quality required for thermal recording media has been diversified with the expansion of applications, and there can be mentioned demands for higher sensitivity, image stabilization, multicolor recording, and the like. In particular, the multi-color recording means has an advantage that characters and figures to be emphasized can be displayed clearly and clearly with a color tone different from other parts, and there is an increasing demand for practical use. Taking advantage of these features, it has recently been used as lottery ticketing paper, and the ability to print in multiple colors can be incorporated as a true / false judgment criterion for lottery ticketing paper. It can be utilized.

  In the case of two-color thermal recording, a structure in which a high-temperature coloring layer and a low-temperature coloring layer are further provided on a support is common. In the coating process, the coating is performed for completeness. However, there may be a case where a coating defect occurs on a part or the whole surface for some reason. If there is an uncoated part of these thermosensitive coloring layers, that part cannot be colored in two colors, and when used for lottery ticketing purposes, it is detected as a counterfeit ticket and is tremendous to the lottery purchaser. May have an impact. In order to avoid such a situation, if an uncoated part occurs in the coating process, it is required to detect it at that time and not put it on the market.

  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 thermal 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). It is disclosed. Furthermore, a method using composite particles composed of an organic polymer and a dye precursor (see Patent Documents 13, 14, 15, and 16) is also disclosed. Furthermore, Np-toluenesulfonyl-N′-3- (p-toluenesulfonyloxy) is used as a developer and composite particles comprising at least one polymer selected from polyurea and polyurethane, and a dye precursor. A method using phenylurea is also disclosed (see Patent Document 16).

  As a means for preventing counterfeiting of the thermal recording material, a method using a near-infrared fluorescent compound (see Patent Documents 17 and 18), a method using a fluorescent agent, a fluorescent dye, and a fluorescent pigment (Patent Documents 19, 20, 21, and 22 and 23), a method using a special pigment ink (see Patent Documents 24 and 25), a method using a support in which a strip thread is drawn (see Patent Document 26), and a watermark on the support. The method used (see Patent Document 27) is disclosed.

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 2001-341432 A JP-A-11-314459 Japanese Patent Laid-Open No. 11-309945 Japanese Unexamined Patent Publication No. 4-135589 Japanese Patent Laid-Open No. 11-129617 JP-A-6-166264 JP-A-7-225488 JP-A-4-363289 JP 2002-293022 A JP 2002-293026 A Japanese Patent Laid-Open No. 2002-19296 JP 2003-200634 A

  An object of the present invention is to provide a multicolor thermosensitive recording medium capable of detecting a coating defect in an upper thermosensitive coloring layer in a two-color thermosensitive coloring layer and a multicolor which eliminates coating defect portions. The object is to provide a method for producing a thermal recording material.

  In order to solve the above problems, the multicolor thermosensitive recording material according to the present invention is provided with a first thermosensitive coloring layer containing a dye precursor that develops black and a developer on the support, and further includes a first thermosensitive coloring layer. By having a second thermosensitive coloring layer containing solid dispersed fine particles composed of a dye precursor that develops a color tone different from the first thermosensitive coloring hue on the thermosensitive coloring layer, a developer and a fluorescent brightening agent, It became possible to solve.

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

Item 1: A first thermosensitive coloring layer containing a black color developing dye precursor and a developer is provided on a support, and a coloring hue different from the color tone of the first thermosensitive coloring layer is further provided on the first thermosensitive coloring layer. A multicolor thermosensitive recording medium comprising a second thermosensitive coloring layer containing solid dispersed fine particles comprising a dye precursor, a developer, and a fluorescent brightening agent.
Item 2: The multicolor thermosensitive recording material according to claim 1, wherein the second thermosensitive coloring layer further contains composite particles comprising an organic polymer and a dye precursor that develops black color.
Item 3: The multicolor thermosensitive recording material according to claim 1 or 2, wherein the fluorescent dye is 0.01 to 5.0 mass% with respect to the total solid content of the second thermosensitive coloring layer.
Item 4: The heat-sensitive recording material according to any one of claims 1 to 3, wherein the first heat-sensitive color-developing layer does not contain a fluorescent brightening agent.
Item 5: The protective layer is further provided on the second thermosensitive coloring layer, and the first thermosensitive coloring layer and the protective layer do not contain a fluorescent brightening agent. Multicolor thermal recording medium.
Item 6: The multicolor thermosensitive recording material according to any one of claims 1 to 5, wherein spherical plastic resin particles or hollow plastic resin particles are contained in the first thermosensitive coloring layer.
Item 7: The multicolor thermal recording material according to any one of Items 1 to 6, wherein the organic polymer is at least one selected from polyurea and polyurea-polyurethane.
Item 8: The developer according to any one of Claims 1 to 7, wherein the developer in the second thermosensitive coloring layer is Np-toluenesulfonyl-N'-3- (p-toluenesulfonyloxy) phenylurea. Multicolor thermal recording material.
Item 9: The developer according to any one of claims 1 to 8, wherein the developer of the first thermosensitive coloring layer is Np-toluenesulfonyl-N'-3- (p-toluenesulfonyloxy) phenylurea. Multicolor thermal recording medium.
Item 10: The multicolor thermosensitive recording material according to any one of Claims 1 to 9, wherein the melting point of the black dye-forming dye precursor of the first thermosensitive coloring layer is 200 ° C or higher.
Item 11: The dye precursor that develops black color in the first thermosensitive coloring layer is 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 The multicolor thermosensitive recording material according to any one of claims 1 to 10, which is at least one selected from (dimethylamino) alinino-5,7-dimethylfluorane.
Item 12: The dye precursor that develops a color tone different from that of the composite particles contained in the second thermosensitive coloring layer is 3- (N-methyl-N-isoamylamino) -7-phenoxyfluorane, 3-diethylamino-7 -Chlorofluorane, 3,3'-bis (1-n-butyl-2-methylindol-3-yl) phthalide, 3-di-N-butylamino-6-methyl-7-bromofluorane, 3- Diethylamino-6-methyl-7-chlorofluorane, 3-cyclohexylamino-6-chlorofluorane, 3-diethylamino-6,8-dimethylfluorane, 7- (N-ethyl-N-isoamylamino) -3- Methyl-1-phenylspiro [(1,4-dihydrochromeno [2,3-c] pyrazole) -4,3′-phthalide], 3- (4-diethylamino-2-methylphenyl) At least one selected from -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide and 3,6-bis (dimethylamino) fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide The multicolor thermosensitive recording material according to claim 1, wherein
Item 13: The dye precursor that develops a color tone different from that of the composite particles contained in the second thermosensitive coloring layer is 3,3′-bis (1-n-butyl-2-methylindol-3-yl) phthalide, 3 At least selected from-(N-methyl-N-isoamylamino) -7-phenoxyfluorane, 3-diethylamino-7-chlorofluorane, 3-di-N-butylamino-6-methyl-7-bromofluorane It is 1 type, The color developer in a 1st thermosensitive coloring layer and a 2nd thermosensitive coloring layer is Np-toluenesulfonyl-N'-3- (p-toluenesulfonyloxy) phenyl urea. The multicolor thermosensitive recording material according to any one of 12 above.
Item 14: The dye precursor used for the composite particles contained in the second thermosensitive coloring layer is 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 3-di (n-pentyl) Amino-6-methyl-7-anilinofluorane, 3-di (n-butylamino) -7- (2-chloroanilino) fluorane, 3- (diethylamino) -6-methyl-7- (3-methylphenylamino) The multicolor thermal recording material according to any one of claims 1 to 13, which is at least one selected from fluoran.
Item 15: 3,3′-bis (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide, 3- [2,2-bis (1-ethyl-) is further added to the composite particles contained in the second thermosensitive coloring layer. The multicolor thermosensitive recording material according to any one of claims 1 to 14, comprising at least one selected from 2-methylindol-3-yl) vinyl] -3- (4-diethylaminophenyl) -phthalide.
Item 16: The multicolor thermosensitive recording material according to any one of claims 1 to 15 is irradiated with ultraviolet rays to measure fluorescence generated from the fluorescent brightening agent, thereby identifying a coating defect location, and A method for producing a multicolor thermal recording medium to be excluded.

  According to the present invention, in a multicolor thermosensitive recording medium, it becomes possible to detect coating defects in the upper thermosensitive coloring layer in the two-layer thermosensitive coloring layer, and by removing the coating defect portion, the entire portion of the thermosensitive recording medium can be detected. Thus, it is possible to provide a multicolor thermosensitive recording medium capable of multicolor development.

  In the multicolor thermosensitive recording material of the present invention, the thermosensitive coloring layer includes a first thermochromic layer containing a black color developing dye precursor and a developer, and further provided on the first thermosensitive coloring layer. It comprises a second thermosensitive coloring layer containing solid dispersed fine particles comprising a dye precursor having a coloring hue different from the color tone of the thermosensitive coloring layer, a developer and a fluorescent brightening agent. In the present invention, the low temperature coloring color tone is the coloring color tone of the dye precursor present in the solid dispersed fine particle state in the second thermosensitive coloring layer.

  In addition, when forming the first thermosensitive coloring layer, coating defects can be detected by the transmission method or the reflection method, but in the defect detection method when forming the second thermosensitive coloring layer, the defect detection is performed by the transmission method or the reflection method. The present invention has been completed because it is very difficult to carry out.

  In addition, by not containing the fluorescent whitening agent in the first thermosensitive coloring layer, it becomes possible to more efficiently detect coating defects in the second thermosensitive coloring layer containing the fluorescent whitening agent.

  The fluorescent whitening agent means a fluorescent substance that absorbs ultraviolet rays and emits fluorescence in the vicinity of 400 to 450 nm.

  Typical fluorescent brighteners include bis (triazinylamino) stilbene disulfonic acid derivatives and bisstyryl biphenyl derivatives represented by the following general formula (1).

（Ｘとしては、−ＮＨ−〔ｂｅｎｚｅｎｅ〕、−ＮＨ−〔ｂｅｎｚｅｎｅ〕−ＣＨ_３、−ＮＨ−〔ｂｅｎｚｅｎｅ〕−ＯＣＨ_３、−ＮＨ−〔ｂｅｎｚｅｎｅ〕−ＳＯ_３Ｎａ、−ＮＨ−〔ｂｅｎｚｅｎｅ〕−ＳＯ_２ＮＨ_２、−ＯＣＨ_３、−ＯＣＨ_２ＣＨ_２ＯＣＨ_３、−Ｃｌ、−ＮＨＣＨ_３があげられ、Ｙとしては、−ＮＨ_２、−ＮＨ−〔ｂｅｎｚｅｎｅ〕、−ＯＣＨ_３、−ＮＨ−ＣＨ_３、−ＮＨ−Ｃ_２Ｈ_５、−ＯＨ、−ＮＨ−ＣＨ_２ＣＨ_２ＯＨ、−Ｎ（ＣＨ_３）ＣＨ_２ＣＨ_２ＯＨ、−Ｎ（ＣＨ_２ＣＨ_２ＯＨ）_２、−〔ｍｏｒｐｈｏｌｉｎｅ〕、−Ｎ（ＣＨ_３）ＣＨ_２ＣＨ_２ＳＯ_３Ｈがあげられる。）

(X is -NH- [benzo], -NH- [benzene] -CH ₃ , -NH- [benzo] -OCH ₃ , -NH- [benzene] -SO ₃ Na, -NH- [benzene]- SO ₂ NH ₂ , —OCH ₃ , —OCH ₂ CH ₂ OCH ₃ , —Cl, —NHCH ₃ may be mentioned, and Y may be —NH ₂ , —NH— [benzene], —OCH ₃ , —NH—CH. _{3, -NH-C 2 H 5} , -OH, -NH-CH 2 CH 2 OH, -N (CH 3) CH 2 CH 2 OH, -N (CH 2 CH 2 OH) 2, - [morpholine], _{-N (CH 3) CH 2 CH} 2 SO 3 H and the like.)

  The fluorescent brightening agent is contained in the second thermosensitive coloring layer. After the second thermosensitive coloring layer is formed, for example, as one method, black light having a spectral distribution of 315 to 380 nm is applied to the second thermosensitive coloring layer surface. The coating defect portion can be detected using a smart view manufactured by Cognex as a detector. That is, since the coating defect portion does not emit fluorescence, the defect portion can be grasped thereby, and finally the defect portion is removed.

In order to be detected by a detector, the fluorescent whitening agent is preferably contained in an amount of 0.01 to 5.0% by mass with respect to the total solid content of the second thermosensitive coloring layer. And the fluorescent brightening agent is more preferable from the viewpoint of the amount of Na ⁺ ions in the thermal recording layer related to the corrosion of the thermal head because Na ⁺ ions are present as shown in the general formula (1). Is 0.1-3.0 mass%, More preferably, it is 0.4-2.8 mass%.

  In the multicolor thermosensitive recording material of the present invention, the second thermosensitive coloring layer further contains composite particles composed of an organic polymer and a black color developing dye precursor, thereby further improving the storage stability of the printed portion, Color development due to pressing force and generation of background fog when stored for a long time in a blank state can be suppressed.

  The composite particles can be produced by the methods described in Patent Documents 13, 14, 15, and 16. As described above, among organic polymers, at least one selected from polyurea and polyurea-polyurethane is preferably used because of particularly good storage stability of the recording portion.

  Here, 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 a dye precursor 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. The solvent solution 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 further, if necessary, a reactive substance such as polyamine is mixed, and then this emulsified dispersion is added. The organic solvent is removed by volatilization by heating, and then the polymer precursor is prepared by polymerizing the polymer former or the dye precursor is dissolved in the polymer former. This is prepared by polymerizing the polymer-forming raw material after emulsification and dispersion by the above method.

  The polymer-forming raw material forming at least one selected from the above polyurea and polyurea-polyurethane may be only a polyvalent isocyanate compound, or a polyvalent isocyanate compound and a polyol, polyamine which reacts with the polyvalent isocyanate compound Or a multimer such as an adduct of a polyvalent isocyanate compound and a polyol, a biuret body, or an isocyanurate body.

  A polyisocyanate compound and water react to form an amine compound, and the amine compound and polyvalent socyanate compound react to form polyurea. Such a reaction further reacts with an organic compound having a hydroxyl group and a polyvalent isocyanate compound to form a polyurea-polyurethane.

  Examples of the polyvalent isocyanate compound used as the polymer-forming raw material include p-phenylene diisocyanate, 1,3-bis (1-isocyanato-1-methylethyl) benzene, 2,6-tolylene diisocyanate, 2,4 -Tolylene diisocyanate, naphthalene-1,4-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, Xylylene-1,4-diisocyanate, 4,4′-diphenylpropane diisocyanate, hexamethylene diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate 4,4 ′, 4 ″ -triphenylmethane triisocyanate, toluene-2,4,6-triisocyanate, trimethylolpropane adduct of hexamethylene diisocyanate, trimethylolpropane addition of 2,4-tolylene diisocyanate And trimethylolpropane adduct of xylylene diisocyanate.

  Examples of the polyol compound used for the polymer-forming raw material include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,7-heptanediol, 1,8-octanediol, propylene glycol, 1,3-dihydroxybutane, 2,2-dimethyl-1,3-propanediol, 2,5-hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanedimethanol, dihydroxycyclohexane, diethylene glycol , Phenylethylene glycol, pentaerythritol, 1,4-di (2-hydroxyethoxy) benzene, 1,3-di (2-hydroxyethoxy) benzene, p-xylylene glycol, m-xylylene glycol, 4,4 ′ -Isopropylidenediphenol, 4 , 4′-dihydroxydiphenylsulfone, 2-hydroxyacrylate and the like.

  Of course, the polyvalent isocyanate compound, the adduct of polyvalent isocyanate and polyol, the polyol compound, and the like are not limited to the above compounds, and two or more kinds may be used in combination as necessary. In addition, it is especially preferable to use what has 3 or more isocyanate groups in a molecule | numerator among the polyvalent isocyanate compounds used in this invention, or the addition product of a polyvalent isocyanate compound and a polyol compound.

  Examples of the polyamine compound used in the polymer-forming raw material of the present invention include ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, p-phenylenediamine, 2,5-dimethylpiperazine, and triethylene. Examples include triamine, triethylenetetramine, diethylaminopropylamine, tetraethylenepentamine, and pentaethylenehexamine.

  In the present invention, a surfactant, an antifoaming agent and the like may be used in addition to the hydrophilic protective colloid agent in the emulsification dispersion during the preparation of the composite particles. The amount of the hydrophilic protective colloid agent used in preparing the composite particles is not particularly limited, but in general, it is preferably 1 to 50% by mass, and about 3 to 30% by mass with respect to the total solid content of the composite particles. More preferably.

  In addition, the content of the dye precursor that develops black color in the composite particles of the present invention is preferably about 5 to 80% by mass, and more preferably about 20 to 50% by mass with respect to the total solid content of the composite particles.

  The average particle size of the composite particles used in the present invention is preferably 0.1 to 15 μm, more preferably adjusted to be in the range of 1.0 to 6.0 μm, in consideration of color development sensitivity. .

  Examples of the dye precursor of the first thermosensitive coloring layer and the composite precursor contained in the second thermosensitive coloring layer used in the present invention include 3-diethylamino-6-methyl-7-anilinofluorane, 3 -Di (n-butyl) amino-6-methyl-7-anilinofluorane, 3-di (n-pentyl) amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N- Isoamylamino) -6-methyl-7-arininofluorane, 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-fluoroanilino) fluorane, 3- (N-cyclohexyl-N-methylamino) -6 Methyl -7-anilinofluorane), 3- (4-dimethylamino) alinino-5,7-dimethylfluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-diethylamino-7- (m-trifluoromethylanilino) fluorane, 3- (N-isoamyl-N-ethylamino) -7- (o- Chloroanilino) fluorane, 3- (N-ethyl-N-2-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3- ( Nn-hexyl-N-ethylamino) -6-methyl-7-anilinofluorane, 3- [N- (3-ethoxypropyl) -N-ethylamino] -6-methyl-7 Anilinofluorane, 3- [N- (3-ethoxypropyl) -N-methylamino] -6-methyl-7-anilinofluorane, 3-diethylamino-7- (2-chloroanilino) fluorane, 3-di At least one of (n-butylamino) -7- (2-chloroanilino) fluorane and 3- (diethylamino) -6-methyl-7- (3-methylphenylamino) fluorane can be used.

  In particular, the dye precursor contained in the first thermosensitive coloring layer is preferably a dye precursor having a melting point of 200 ° C. or more from the viewpoint of color separation, for example, 3- (N-ethyl-p-toluidino) -6-methyl-anilino. Fluorane, 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., but high sensitivity and excellent light resistance 3 because it (N- ethyl -p- toluidino) -6-methyl-7-anilinofluoran is preferable.

  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-methylphenylamino) Fluoran is more preferable because it hardly causes background fogging.

  The composite particles used in the present invention include 3,3′-bis (4-diethylamino-2-ethoxyphenyl), in addition to a dye precursor that develops a black color, in order to improve the readability with a barcode reader. ) -4-Azaphthalide, dyes such as 3- [2,2-bis (1-ethyl-2-methylindol-3-yl) vinyl] -3- (4-diethylaminophenyl) -phthalide, recorded if necessary Aromatic organic compounds (sensitizers) with a melting point of about 40 to 150 ° C. to increase sensitivity, UV absorbers to increase light resistance, antioxidants, oil-soluble fluorescent dyes, release agents, etc. are added. May be. Such an additive substance is preferably solid at room temperature, but may be liquid. The dye precursor that produces black color may be a mixture of two or more dye precursors. When making the composite particles contain a dye precursor with a color tone that becomes a black color tone by mixing with the color tone formed by low-temperature color development, that is, a color tone that is complementary to the color tone, thereby making the high-temperature color tone black It is possible to obtain a high-temperature coloring color tone with a stronger blackness. In this case, a black color-forming dye precursor and a dye precursor that develops a color tone complementary to the low-temperature color tone can be used in combination as a dye precursor in the composite particles. Only a dye precursor that develops a color tone that is complementary to the color tone may be contained in the composite particles as a single dye precursor.

  Further, by including spherical plastic resin particles or hollow plastic resin particles in the first thermosensitive coloring layer, the coloring density of the color that develops in a color tone different from black is improved, and as a result, the contrast of the two colors is improved. In addition, it has become possible to greatly improve the storage stability of a color that develops in a color tone different from that of black, particularly the chemical resistance of plasticizers and oils.

  Such spherical plastic resin particles are resin particles mainly composed of polystyrene, and the main monomer is styrene, and aromatic vinyl compounds such as α-methylstyrene and vinyltoluene, methyl acrylate, ethyl acrylate, acrylic Resin particles using acrylic acid esters such as butyl acid, 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.

  Moreover, as a hollow plastic resin particle, a conventionally well-known thing, for example, the particle | grains whose hollow rate consists of an acrylic resin, a styrene resin, a vinylidene chloride resin etc. about 50-99% can be illustrated. Here, the hollowness is a value obtained by (d / D) × 100. In the formula, d represents the inner diameter of the hollow plastic resin particle, and D represents the outer diameter of the hollow plastic resin particle. The average particle diameter of the hollow plastic resin particles is preferably about 0.5 to 10 μm, particularly preferably about 0.7 to 2 μm.

  The content of the spherical plastic resin particles or hollow plastic resin particles used in the present invention is 2 to 30% by mass, preferably 5 to 20% by mass, preferably 2 to 30% by mass, based on the total solid content of the first thermosensitive coloring layer. If it is within the range, the color density of the color that develops in a color tone different from that of black is improved. As a result, the contrast of the two colors is improved, and the chemical resistance improving effect is further increased.

  As the dye precursor that develops a color tone different from that of the composite particles contained in the second heat-sensitive layer, a dye precursor that develops a color tone different from black, for example, red, magenta, orange, blue, green, etc. The body is raised.

  For example, 3,6-bis (diethylamino) fluorane-γ-anilinolactam, 3,6-bis (diethylamino) fluorane-γ- (p -Nitro) anilinolactam, 3,6-bis (diethylamino) fluorane-γ- (o-chloro) anilinolactam, 3-dimethylamino-7-bromofluorane, 3-diethylaminofluorane, 3-diethylamino-6 -Methylfluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-bromofluorane, 3-diethylamino-7,8-benzofluorane, 3-diethylamino -6,8-dimethylfluorane, 3-diethylamino-6-methyl-7-chloro Luolan, 3-diethylamino-7-tert-butylfluorane, 3- (N-ethyl-N-tolylamino) -7-methylfluorane, 3- (N-ethyl-N-tolylamino) -7-ethylfluorane, 3- (N-methyl-N-isoamylamino) -7-phenoxyfluorane, 3- (N-ethyl-N-isobutylamino) -6-methyl-7-chlorofluorane, and 3- (N-ethyl- N-isoamylamino) -7,8-benzofluorane.

  Examples of dye precursors that give red, magenta and orange color shades include 3-cyclohexylamino-6-chlorofluorane, 3-di-n-butylamino-6-methyl-7-bromofluorane, 3-di-n-butylamino-7,8-benzofluorane, 3-tolylamino-7-methylfluorane, 3-tolylamino-7-ethylfluorane, 2- (N-acetylanilino) -3-methyl -6-di-n-butylaminofluorane, 2- (N-propionylanilino) -3-methyl-6-di-n-butylaminofluorane, 2- (N-benzoylanilino) -3-methyl -6-di-n-butylaminofluorane, 2- (N-carbobutoxyanilino) -3-methyl-6-di-n-butylaminofluorane, 2- (N-formylanilino) -3 Methyl-6-di-n-butylaminofluorane, 2- (N-benzylanilino) -3-methyl-6-di-n-butylaminofluorane, 2- (N-allylanilino) -3-methyl- Examples thereof include 6-di-n-butylaminofluorane and 2- (N-methylanilino) -3-methyl-6-di-n-butylaminofluorane.

  Further, 3,3′-bis (1-n-butyl-2-methylindol-3-yl) phthalide, 3,3′-bis as dye precursors exhibiting red, magenta, and orange color tone (1-Ethyl-2-methylindol-3-yl) phthalide, 3,3′-bis (1-n-octyl-2-methylindol-3-yl) phthalide, 7- (N-ethyl-N-isoamyl) Amino) -3-methyl-1-phenylspiro [(1,4-dihydrochromeno [2,3-c] pyrazole) -4,3′-phthalide], 7- (N-ethyl-N-isoamylamino) -3-methyl-1-p-methylphenylspiro [(1,4-dihydrochromeno [2,3-c] pyrazole) -4,3′-phthalide], and 7- (N-ethyl-Nn) -Hexylamino) -3-methyl-1-pheni Spiro [(1,4-dihydro-chromate Bruno [2,3-c] pyrazole) 4,3' phthalide] and the like.

  Among the above-mentioned compounds, 3-diethylamino-7-chlorofluorane and 3-diethylamino-6-methyl-7- are examples of dye precursors that give red coloration because they have high color development sensitivity and little background fogging. Chlorofluorane, 3- (N-methyl-N-isoamylamino) -7-phenoxyfluorane is preferred, and as the dye precursor that gives orange color, 3-cyclohexylamino-6-chlorofluorane, 3-diethylamino -6,8-dimethylfluorane, and 7- (N-ethyl-N-isoamylamino) -3-methyl-1-phenylspiro [(1,4-dihydrochromeno [2,3-c] pyrazole)- 4,3′-phthalide], and 3,3′-bis (1-n-butyl-2-methyl ester) is preferable as a dye precursor that gives a reddish purple color. Doll-3-yl) phthalide is preferred. Note that 3,3′-bis (1-n-butyl-2-methylindol-3-yl) phthalide is excellent in oil resistance of the recording portion. In particular, when 3-diethylamino-7-chlorofluorane or 3-diethylamino-6-methyl-7-chlorofluorane is used as a red coloring dye precursor, dyes having different color tones are used for color correction. It is rather desirable to use a mixture, such as 3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide or 3,3′-bis (1-ethyl-2-methylindole-3). -Il) By blending a small amount of a dye precursor that develops a reddish purple color tone such as phthalide, it is possible to develop a color tone that feels more reddish.

Examples of dye precursors that give blue color development include 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylamino). Phenyl) -6-dimethylaminophthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (4-diethylaminophenyl) phthalide, 3- (1-ethyl-2-methylindole-3) -Yl) -3- (2-methyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-n-hexyloxy-4-diethylaminophenyl)- - azaphthalide, and 3-diphenyl-amino-6-diphenylamino fluoran and the like. In particular, among these blue color-forming dye precursors, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide is said to have less background fog. It is preferable from the point.

  Examples of the dye precursor that gives green color development include 3- (N-ethyl-Nn-hexylamino) -7-anilinofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3,3-bis ( 4-diethylamino-2-ethoxyphenyl) -4-azaphthalide, 3- (N-ethyl-Np-tolylamino) -7- (N-phenyl-N-methylamino) fluorane, 3- [p- (p- Anilinoanilino) anilino] -6-methyl-7-chlorofluorane, 3,6-bis (dimethylamino) fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide, and the like. Among these, 3,6-bis (dimethylamino) fluorene-9-spiro-3 ′-(6′-dimethylamino) phthalide is preferable from the viewpoint that there is little background fog.

  Examples of dye precursors that give yellowish color development include 3,6-dimethoxyfluorane and 1- (4-n-dodecyloxy-3-methoxyphenyl) -2- (2-quinolyl) ethylene. The above dye precursor may be used alone, but it is also effective to use it together with other color developing dyes for color tone correction.

  In the present invention, when the dye precursor is used as a dye precursor 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. Water-soluble synthetic polymer compounds such as polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, modified polyvinyl alcohols such as sulfone group-modified polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, styrene-maleic anhydride copolymer salts and derivatives thereof. In addition, if necessary, it is 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 the preparation of a coating for forming 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 diameter of the dispersed particles of the dye precursor used in the solid fine particle state is preferably 0.2 to 3.0 μm, more preferably 0.3 to 3.0 in order to obtain appropriate color development sensitivity. 1.0 μm.

  In the second thermosensitive coloring layer, about 50 to 2000 parts by mass, preferably about 100 to 1500 parts by mass of the dye precursor that develops a different color tone with respect to 100 parts by mass of the dye precursor in the composite particles. is there.

  As the developer used in the present invention, 4-tert-butylphenol, 4-acetylphenol, 4-tert-octylphenol, 4,4′-sec-butylidenediphenol, 4-phenylphenol, 4,4′-dihydroxy Diphenylmethane, 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-hydroxyphenyl) sulfur , Phenolic compounds such as bis (p-hydroxyphenyl) butyl acetate and methyl bis (p-hydroxyphenyl) acetate, 4-hydroxybenzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, 4-hydroxybenzoate Propyl acid, 4-hydroxybenzoic acid-sec-butyl, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, tolyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, 4,4′-dihydroxydiphenyl ether, etc. Phenolic compounds, or benzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, salicylic acid, 3-tert-butylsalicylic acid, 3-isopropylsalicylic acid, 3-benzylsalicylic acid, 3- (α-methyl) Nzyl) salicylic acid, aromatic carboxylic acids such as 3,5-di-tert-butylsalicylic acid, and these phenolic compounds, salts of aromatic carboxylic acids with polyvalent metals such as zinc, magnesium, aluminum, calcium, etc. Organic acidic substance, Np-toluenesulfonyl-N′-3- (p-toluenesulfonyloxy) phenylurea, N- (p-toluenesulfonyl) -N ′-(p-butoxycarboyl) urea, Np And urea compounds such as -tolylsulfonyl-N'-phenylurea.

  Among these developers, Np-toluenesulfonyl-N′-3- (p-toluenesulfonyloxy) is used for the thermosensitive coloring layer from the viewpoints of storage stability, sensitivity, and heat resistance during high temperature storage (background fogging). It is preferable to use phenylurea, and it is more preferable to use the same developer for the first and second thermosensitive coloring layers from the viewpoint of background fogging during high-temperature storage. Furthermore, 3,3′-bis (1-n-butyl-2-methylindol-3-yl) phthalide is used as the dye precursor that develops a color tone different from that of the composite particles contained in the second thermosensitive coloring layer. When Np-toluenesulfonyl-N′-3- (p-toluenesulfonyloxy) phenylurea is used as a color developer for the first and second thermosensitive coloring layers, the heat resistance (background fogging) during high-temperature storage is also obtained. It is more preferable because of its excellent chemical resistance such as plasticizer and oil.

  The developer is usually preferably used in an amount of 100 to 700 parts by mass, more preferably 150 to 400 parts by mass, with respect to 100 parts by mass in total of the dye precursor. Of course, if necessary, two or more colorants can be used in combination.

  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 ester) 1) One or more selected from epoxy compounds such as diphenylsulfone and isocyanuric acid compounds such as 1,3,5-tris (2,6-dimethylbenzyl-3-hydroxy-4-tert-butyl) isocyanuric acid What is included 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.

  In order to adjust the color development sensitivity of the thermosensitive coloring layer of the thermosensitive recording material, a thermofusible substance can be contained in the thermosensitive coloring layer as a sensitizer. As the sensitizer, compounds conventionally known as sensitizers for thermal recording materials can be used. For example, parabenzylbiphenyl, dibenzyl terephthalate, phenyl 1-hydroxy-2-naphthoate, dibenzyl oxalate Di-o-chlorobenzyl adipate, 1,2-di (3-methylphenoxy) ethane, di-p-methylbenzyl oxalate, di-p-chlorobenzyl oxalate, 1,2-bis (3,4 -Dimethylphenyl) ethane, 1,3-bis (2-naphthoxy) propane and the like can be mentioned. In particular, when di-p-methylbenzyl oxalate and di-p-chlorobenzyl oxalate are used as sensitizers, a sensitizing effect with less fog is obtained.

  Additives such as developers, image stabilizers, and sensitizers used in the present invention are dispersed in water in the same manner as when the dye precursor is used in the form of solid fine particles, so 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 calcium carbonate and silica, etc. Inorganic pigments and 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 lower the color density, that is, 50% by mass or less based on the total solid content weight of the thermosensitive 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 the like 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, acrylic ad-acrylic acid ester-methacrylic acid ester copolymer, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, casein, gelatin and derivatives thereof, Polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylic ester, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, ethylene-vinyl acetate copolymer Emulsions and styrene etc - butadiene copolymer, styrene - butadiene - such as latex of water-insoluble polymers such as acrylic copolymers and the like.

  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, and ammonium persulfate, ferric chloride, and chloride At least one crosslinking agent selected from inorganic compounds such as magnesium, sodium tetraborate, potassium tetraborate or the like, boric acid, boric acid triester, boron-based polymer, etc. It is preferable to use in the range of -10 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 higher. 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.

  There are no particular limitations on the type, shape, dimensions, and the like of the support material used in the present invention. Examples include high-quality paper (acidic paper, neutral paper), medium-quality paper, coated paper, art paper, cast-coated paper, In addition to glassine paper, resin-laminated paper, polyolefin-based synthetic paper, synthetic fiber paper, non-woven fabric, synthetic resin film, and the like, various transparent supports can be appropriately selected and used.

  In the present invention, in order to increase the added value of the multicolor thermal recording material, it can be further processed to provide a thermal recording material having a higher function. For example, adhesive paper, rewet adhesive paper, delayed tack paper can be used by applying coating with adhesive, rewet adhesive, delayed tack type adhesive, etc. on the back side, or magnetic processing is applied Thus, a thermosensitive recording material having a magnetically recordable layer on the back surface can be obtained. In particular, those subjected to adhesive processing and magnetic processing are useful for applications such as two-color heat-sensitive labels and two-color heat-sensitive magnetic tickets. Further, by using the back surface, a function as a thermal transfer paper, an ink jet paper, a carbonless paper, an electrostatic recording paper, and a xerographic paper can be added to the recording paper which can be recorded on both sides. Of course, a double-sided thermal recording material can also be used. As the multicolor thermal recording material of the present invention, when two or more types of two-color thermal recording materials having different low-temperature color tone are used, various colors such as file color coding, delivery destination color coding, receipt and journal color coding, etc. It becomes possible to perform recognition with different colors depending on the application.

  In the present invention, a protective layer can be provided on the thermosensitive coloring layer, and an undercoat layer can be provided below the thermosensitive coloring layer. As these additional layers, there can be used a protective layer and an undercoat layer that are used in conventionally known heat-sensitive recording materials. Both the protective layer and the undercoat layer are mainly composed of a pigment and an adhesive. In particular, a lubricant such as polyolefin wax and zinc stearate is preferably added to the protective layer for the purpose of preventing sticking to the thermal head, and it may be composed of two or more layers. In addition, the added value of the product can be increased by providing a glossy protective layer.

  By using a pigment having a high porosity such as silica or calcined kaolin for the undercoat layer, the color development sensitivity of the thermosensitive color developing layer thereon can be increased. In addition, the inclusion of plastic pigments, hollow particles, foams and the like in the undercoat layer is also effective for improving the color development sensitivity of the thermosensitive color development layer formed thereon.

  A protective layer containing a UV curable resin or an EB curable resin can be provided on the thermosensitive coloring layer of the present invention, and printing can be performed with UV ink, flexographic ink or the like thereon. By using a release agent such as silicon for the protective layer, the heat-sensitive recording material of the present invention can also be used as a linerless adhesive label. In this case, a release agent may be applied after printing.

As a method for forming each layer on the support, 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 an extrusion method is used. May be. It is also possible to partially print the heat-sensitive color developing layer paint of the present invention using a printing machine or the like. The heat-sensitive coloring layer coating is applied to one surface of the support so that the weight after drying is 1 to 10 g / m ^{2 for the first} and ^second heat-sensitive coloring layers, thereby forming the heat-sensitive coloring layer. Is done. Further, a back layer can be provided for suppressing permeation of oil and plasticizer from the back surface of the recording material, or for curling control.
Further, smoothing the thermosensitive coloring layer using a known smoothing method such as a super calender or a soft calender is effective in increasing the coloring sensitivity. The surface of the heat-sensitive color developing layer may be applied to either a calendar metal roll or an elastic roll.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Unless otherwise specified, “parts” and “%” represent “parts by mass” and “mass%”, respectively.

Example 1
・ Preparation of paint for undercoat layer 88 parts of calcined kaolin having an oil absorption of 110 ml, 20 parts of styrene-butadiene latex (solid content concentration: 50%), 5 of carboxymethylcellulose (trade name: Cellogen 7A, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) An undercoat layer coating solution was obtained by uniformly mixing 20 parts of a 20% aqueous solution, 5 parts of a 20% aqueous solution of sodium polyacrylate, and 190 parts of water.

-Preparation of dye precursor-containing composite particle dispersion (liquid A) 6 parts 3- (diethylamino) -6-methyl-7- (3-methylphenylamino) fluorane and 2-hydroxy-4- as UV absorber 3 parts of octyloxybenzophenone is dissolved in 9 parts of dicyclohexylmethane-4,4′-diisocyanate (manufactured by Sumitomo Urethane) heated to 100 ° C., this solution is cooled to 35 ° C., and then 12% partially saponified polyvinyl alcohol at the same temperature. (Product name: PVA217EE, manufactured by Nippon Synthetic Chemical Industry) Gradually added to 66.7 parts of aqueous solution, emulsified and dispersed by stirring at a rotation speed of 8000 rpm using a homogenizer, and then 6 parts of water was added to the emulsified dispersion uniformly. Turned into. This emulsified dispersion was heated to 90 ° C. and subjected to a curing reaction for 10 hours using an amine-based crosslinking agent, and then water was added so that the solid content concentration became 23%. An 8 μm composite particle dispersion was obtained.

-Preparation of Dye Precursor Dispersion (Liquid B) 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane 20 parts, sulfone-modified polyvinyl (trade name: Goceran L-3266 , Nippon Synthetic Chemical Industry Co., Ltd.) 10 parts of 20% liquid and 20 parts of water were pulverized and dispersed using a vertical sand mill (Imex Co., Ltd., sand grinder) 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.) 10 parts of 20% liquid 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 developer dispersion (liquid D) 20 parts of Np-toluenesulfonyl-N'-3- (p-toluenesulfonyloxy) phenylurea, sulfone-modified polyvinyl (trade name: Goceran L-3266, 10 parts of 20% liquid (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and 30 parts of water were 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 sensitizer dispersion (solution E) 1: 1 mixture of di-p-methylbenzyl oxalate and di-p-chlorobenzyl oxalate (trade name: HS7150, manufactured by Dainippon Ink & Chemicals) 20 Part, 10 parts of 20% liquid of sulfone-modified polyvinyl (trade name: Goseiran L-3266, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and 30 parts of water using a vertical sand mill (made by Imex Corporation, sand grinder), The particles were pulverized and dispersed so that the average particle size was 1.0 μm.

-Preparation of coating liquid for first thermosensitive coloring layer B part 30 parts, D part 80 parts, E part 60 parts, aluminum hydroxide 10 parts, polyvinyl alcohol (trade name: PVA110, manufactured by Kuraray Co., Ltd.) 10 parts aqueous solution 100 parts And 50 parts of water were mixed and stirred uniformly to obtain a first thermosensitive coloring layer coating solution.

-Preparation of coating solution for second thermosensitive coloring layer A part 44 parts, C part 40 parts, D part 100 parts, E part 30 parts, aluminum hydroxide 10 parts, polyvinyl alcohol (trade name: PVA110, manufactured by Kuraray Co., Ltd.) 200 parts of a 10% aqueous solution, 2 parts of a fluorescent brightener (trade name: Kayahole BPS Liquid Conk, manufactured by Nippon Kayaku Co., Ltd.) and 50 parts of water were uniformly mixed and stirred to obtain a coating solution for a second thermosensitive coloring layer.

-Preparation of coating solution for protective layer Diacetone-modified polyvinyl alcohol (trade name: D-610, manufactured by Nihon Vinegar Bipoval) 20% liquid 200 parts, aluminum hydroxide 60 parts, zinc stearate 30% dispersion (trade name: Hydrin Z-7 (manufactured by Chukyo Yushi Co., Ltd.) and 135 parts of water were uniformly mixed to obtain a coating solution for a protective layer.

・ Preparation of multicolor thermal recording material The coating amount after drying the coating solution for the undercoat layer and the coating solution for the first thermosensitive coloring layer on one side of a high-quality paper (paper surface pH 5.9) having a basis weight of 81.4 g / m ^2. Was coated and dried so as to be 8 g / m ² and 4 g / m ^2, and coating defects were detected by using both the transmission method and the reflection method, and wound up. Thereafter, by applying a black light by coating and drying as the coating amount after drying the second thermosensitive coloring layer coating liquid and protective layer coating liquid, respectively is 3 g / m ^2, and 2 g / m ^2, produced Fluorescence is detected by a detector to detect the coating defect of the second thermosensitive coloring layer, and at the same time, the coating defect of the protective layer is detected by using both the transmission method and the reflection method. A multicolor thermosensitive recording material having a first thermosensitive coloring layer, a second thermosensitive coloring layer and a protective layer in sequence was obtained. Thereafter, a super-calendar was used to smooth the thermal recording surface so that the Beck smoothness (JIS-P8119) was 3500 seconds, thereby producing a multicolor thermal recording material.

Example 2
In Example 1, the multicolor thermal sensitivity was the same as in Example 1 except that 2 parts of the fluorescent whitening agent (trade name: Kaya Hall BPS Liquid Conk, supra) in the second thermal recording layer was changed to 0.3 part. A recording body was produced.

Example 3
In Example 1, a multicolor thermosensitive recording material was used in the same manner as in Example 1 except that 2 parts of the fluorescent whitening agent (trade name: Kaya Hall BPS Liquid Conk, supra) in the second thermosensitive recording layer was changed to 4 parts. Was made.

Example 4
In the preparation of solution C of Example 1, 3- (N-methyl-N-isoamylamino) -7 instead of 3,3′-bis (1-n-butyl-2-methylindol-3-yl) phthalide A multicolor thermosensitive recording material was produced in the same manner as in Example 1 except that phenoxyfluorane was used.

Example 5
Except that 3-diethylamino-7-chlorofluorane was used in place of 3,3′-bis (1-n-butyl-2-methylindol-3-yl) phthalide in the preparation of solution C of Example 1. A multicolor thermal recording material was produced in the same manner as in Example 1.

Example 6
In preparing the liquid C used for the second thermosensitive coloring layer coating liquid of Example 1, 3-diethylamino instead of 3,3′-bis (1-n-butyl-2-methylindol-3-yl) phthalide In the preparation of solution D using -7-chlorofluorane and also used in the coating solution for the second thermosensitive coloring layer, the developer Np-toluenesulfonyl-N′-3- (p-toluenesulfonyloxy) was used. ) A multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that 4-hydroxy-4'-isopropoxydiphenylsulfone was used instead of phenylurea.

Example 7
In the preparation of the liquid D used for the first thermosensitive color-developing layer coating liquid of Example 1, instead of the developer Np-toluenesulfonyl-N′-3- (p-toluenesulfonyloxy) phenylurea, 4 was used. A multicolor thermosensitive recording material was produced in the same manner as in Example 1 except that -hydroxy-4'-isopropoxydiphenyl sulfone was used.

Example 8
In the preparation of the liquid D used for the first thermosensitive coloring layer coating liquid of Example 1, bis instead of the developer Np-toluenesulfonyl-N′-3- (p-toluenesulfonyloxy) phenylurea was used. A multicolor thermosensitive recording material was produced in the same manner as in Example 1 except that (p-hydroxyphenyl) butyl acetate was used.

Example 9
A multicolor thermosensitive recording material was produced in the same manner as in Example 1 except that the sensitizer dispersion liquid (E liquid) was not used in the preparation of the first thermosensitive coloring layer coating liquid of Example 1.

Example 10
In the preparation of the liquid B used for the first thermosensitive coloring layer coating liquid of Example 1, instead of the dye precursor 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane A multicolor thermosensitive recording material was produced in the same manner as in Example 1 except that 3-di (n-pentyl) amino-6-methyl-7-anilinofluorane was used.

Example 11
In the preparation of solution A of Example 1, 3- (diethylamino) -6-methyl-7- (3-methyl) instead of 6 parts of 3- (diethylamino) -6-methyl-7- (3-methylphenylamino) fluorane Except that 3 parts of phenylamino) fluorane and 3 parts of 3- [2,2-bis (1-ethyl-2-methylindol-3-yl) vinyl] -3- (4-diethylaminophenyl) phthalide were used, A multicolor thermosensitive recording material was produced in the same manner as in Example 1.

Example 12
In preparing the first thermosensitive coloring layer coating solution of Example 1, 25 parts of spherical plastic particle dispersion (trade name: Grosdale 130S, solid content: 53%, manufactured by Mitsui Chemicals, Inc.) was used instead of 10 parts of aluminum hydroxide. A multicolor thermosensitive recording material was produced in the same manner as in Example 1 except that.

Example 13
In the preparation of the first thermosensitive coloring layer coating liquid of Example 1, 45 parts of hollow plastic resin particle dispersion (trade name: AE851, solid content: 28%, manufactured by JSR) was used instead of 10 parts of aluminum hydroxide. Produced a multicolor thermal recording material in the same manner as in Example 1.

Example 14
A multicolor thermosensitive recording material was produced in the same manner as in Example 1 except that the liquid A of the first thermosensitive coloring layer of Example 1 was not used.

Example 15
In the preparation of the coating solution for the second thermosensitive coloring layer of Example 1, solution A was not used, but instead of solution B, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane. A multicolor thermosensitive recording material was produced in the same manner as in Example 1 except that 60 parts of a dispersion using 3-di (n-pentyl) amino-6-methyl-7-anilinofluorane was used.

Comparative Example 1
A multicolor thermosensitive recording material was produced in the same manner as in Example 1 except that the fluorescent whitening agent was not used in the preparation of the second thermosensitive coloring layer coating solution of Example 1.

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

・ Printing test Using a printer (model name: High Quality Printer L-2000, manufactured by Ishida Co., Ltd.), low energy: printing density setting 10, high energy: printing density setting 18, printing speed: 125 mm / s A test was conducted.

  The color development part thus obtained was evaluated according to the following evaluation criteria.

-Color density For the low energy color development part, the density value obtained using the cyan filter was subtracted from the density value obtained using the magenta filter with a Macbeth densitometer (RD-914 type, manufactured by Macbeth). The numerical value was defined as the color density, and the density value obtained by using a cyan filter was defined as the color density for the high energy color development part.

-Two-color separation property (circle): The low energy coloring part (red) was clear and was excellent in two-color separation property.
Δ: Color development in which the low energy color development part is slightly mixed with the color tone of the high energy color development part, but the separation of the two colors is at a level that causes no problem in practice.
X: Color development in which the low energy color development portion was mixed with the color tone of the high energy color development portion, and the two colors were not separated.

・ Oil resistance Soaked edible oil with a cotton swab, 10 reciprocations on the high-energy color development part, 1 hour after wiping, and 1 week later, the color density of the high-energy color development part is measured with a Macbeth densitometer (RD-914 type, manufactured by Macbeth). Measurements were made using a cyan filter.

  Regarding defect detectability, can a coating defect be intentionally generated in the second thermosensitive coloring layer during the production of a multicolor thermosensitive recording medium and the coating defect of the second thermosensitive coloring layer can be detected after the protective layer is formed? We evaluated whether.

-Defect detectability Black light having a spectral distribution of 315 to 380 nm was applied, and the detection level of the coating defect of the second thermosensitive coloring layer was confirmed using a smart view manufactured by Cognex.
: Easy to detect.
○: Detectable.
×: Cannot be detected.

Claims (15)

Provided on the support is a first thermosensitive coloring layer containing a black color developing dye precursor and a developer, and further has a coloring precursor having a coloring hue different from the color tone of the first thermosensitive coloring layer on the first thermosensitive coloring layer. solid dispersion particulates consisting of the body, have a second thermosensitive coloring layer containing the developer and fluorescent whitening agent, wherein the first thermosensitive coloring layer, characterized in that it does not contain a fluorescent whitening agent multicolor heat-sensitive Recorded body.   2. The multicolor thermosensitive recording material according to claim 1, wherein the second thermosensitive coloring layer further contains composite particles composed of an organic polymer and a black dye-forming dye precursor.   The multicolor thermal recording material according to claim 1 or 2, wherein the fluorescent whitening agent is 0.01 to 5.0% by mass relative to the total solid content of the second thermosensitive coloring layer. The multicolor thermosensitive according to any one of claims 1 to 3 , wherein a protective layer is further provided on the second thermosensitive coloring layer, and the first thermosensitive coloring layer and the protective layer do not contain a fluorescent brightening agent. Recorded body. It was contained spherical plastic resin particles or hollow plastic resin particles in the first thermosensitive coloring layer, a multicolor heat-sensitive recording material according to any one of claims 1-4. The multicolor thermal recording material according to any one of claims 1 to 5 , wherein the organic polymer is at least one selected from polyurea and polyurea-polyurethane. The multicolor according to any one of claims 1 to 6 , wherein the developer in the second thermosensitive coloring layer is Np-toluenesulfonyl-N'-3- (p-toluenesulfonyloxy) phenylurea. Thermal recording material. The multicolor thermosensitive material according to any one of claims 1 to 7 , wherein the developer of the first thermosensitive coloring layer is Np-toluenesulfonyl-N'-3- (p-toluenesulfonyloxy) phenylurea. Recorded body. The multicolor thermosensitive recording material according to any one of claims 1 to 8 , wherein a melting point of a dye precursor that develops black color in the first thermosensitive coloring layer is 200 ° C or higher. The dye precursor that develops black color in the first thermosensitive coloring layer is 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) The multicolor thermosensitive recording material according to any one of claims 1 to 9 , which is at least one selected from alinino-5,7-dimethylfluorane. Dye precursors that develop colors different from the composite particles contained in the second thermosensitive coloring layer are 3- (N-methyl-N-isoamylamino) -7-phenoxyfluorane, 3-diethylamino-7-chlorofluol. Oran, 3,3′-bis (1-n-butyl-2-methylindol-3-yl) phthalide, 3-di-N-butylamino-6-methyl-7-bromofluorane, 3-diethylamino-6 -Methyl-7-chlorofluorane, 3-cyclohexylamino-6-chlorofluorane, 3-diethylamino-6,8-dimethylfluorane, 7- (N-ethyl-N-isoamylamino) -3-methyl-1 -Phenylspiro [(1,4-dihydrochromeno [2,3-c] pyrazole) -4,3'-phthalide], 3- (4-diethylamino-2-methylphenyl) -3- It is at least one selected from 4-dimethylaminophenyl) -6-dimethylaminophthalide and 3,6-bis (dimethylamino) fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide. Item 11. The multicolor thermal recording material according to any one of Items 1 to 10 . A dye precursor that develops a color tone different from that of the composite particles contained in the second thermosensitive coloring layer is 3,3′-bis (1-n-butyl-2-methylindol-3-yl) phthalide, 3- (N -Methyl-N-isoamylamino) -7-phenoxyfluorane, 3-diethylamino-7-chlorofluorane, 3-di-N-butylamino-6-methyl-7-bromofluorane , the color developer of the first thermosensitive coloring layer and a second thermosensitive coloring layer is an N-p-toluenesulfonyl-N'-3- (p-toluenesulfonyloxy) phenylurea, any claim 1 to 11 The multicolor thermal recording material according to claim 1. The dye precursor used for the composite particles contained in the second thermosensitive coloring layer is 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 3-di (n-pentyl) amino-6. From -methyl-7-anilinofluorane, 3-di (n-butylamino) -7- (2-chloroanilino) fluorane, 3- (diethylamino) -6-methyl-7- (3-methylphenylamino) fluorane The multicolor thermosensitive recording material according to any one of claims 1 to 12 , which is at least one selected. In the composite particles contained in the second thermosensitive coloring layer, 3,3′-bis (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide, 3- [2,2-bis (1-ethyl-2-methyl) is further added. The multicolor thermosensitive recording material according to any one of claims 1 to 13 , comprising at least one selected from indol-3-yl) vinyl] -3- (4-diethylaminophenyl) -phthalide. A multicolor thermosensitive recording material according to any one of claims 1 to 14 , wherein ultraviolet rays are irradiated to measure fluorescence generated from the fluorescent brightening agent to identify a coating defect location and eliminate the location. A method for producing a color thermal recording material.