JP2003105223A - Dye precursor composite and multicolor heat sensitive recording body using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multicolor heat sensitive recording body in which a recorded image having a high recording density and a clear color tone is obtained. SOLUTION: In the recording body equipped with a heat sensitive color developing layer on a support, which contains two or more kinds of colorless or light-colored electron donable dye precursors respectively developing colors different in color tones from each other and an electron accepting organic compound developing colors by reacting with the dye precursors, at least one kind of the dye precursor is a dye precursor composite coated with a resinous film of a polyisocyanate compound.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a dye precursor composite comprising a dye precursor and a resin film of a water-dispersible polyisocyanate compound, and a multicolor heat-sensitive recording material using the same.

[0002]

2. Description of the Related Art A heat-sensitive recording material generally has a heat-sensitive coloring layer mainly composed of a colorless or light-colored electron-donating dye precursor and an electron-accepting organic compound on a support. By heating with a pen / laser light or the like, the electron-donating dye precursor and the electron-accepting organic compound are made compatible and react with each other to obtain a color recorded image. Such a thermal recording medium is generally advantageous in that the recording device is compact and inexpensive, maintenance is easy, and there is little noise generation. The output label of the measuring recorder, facsimile, printer, register, etc. Although it is used in a wide range of fields such as, the required quality is diversifying with the expansion of its application, and in particular, regarding multicolor recording, there is an increasing demand for its practical application in terms of its visual effect. A multicolor thermosensitive recording medium generally comprises a support having a single-layer or a plurality of color-developing layers, and a plurality of color-developing hues depending on the difference in applied energy. In the case of a single layer type containing two or more kinds of dye precursors that develop different colors in the same thermosensitive coloring layer, these methods usually produce a clear hue by mixing a high temperature coloring color with a low temperature coloring color. In the case of a multi-layer type in which a high-temperature coloring layer and a low-temperature coloring layer are laminated, it is inevitable that the manufacturing process becomes complicated due to the multilayer structure. In order to obtain a clear multicolored color, Japanese Patent Laid-Open No.
No. 0-242093 describes that two or more types of microcapsules having different glass transition temperatures contain a color-forming component that develops a different color tone. However, when the dyes that develop different color tones are separately encapsulated in microcapsules, there is a problem in that the color development sensitivity is lowered and the color separation properties are poor because they are completely isolated from the capsule wall.

Japanese Unexamined Patent Publication No. 2000-177251 describes microcapsules containing a leuco dye in a solid state and easily broken during thermal recording. However, since they are easily broken, they are inferior in ground color and scratch resistance. When the wall film material is gelatin, the moisture resistance is poor and a multicolor thermosensitive recording medium of sufficient quality cannot be obtained. Further, in JP-A-9-76634, an oil solution containing a dye as a solute and an organic solvent as a solvent is emulsified and dispersed in an aqueous liquid to form a wall film made of a polymer substance around the oil droplets. It is described that the microcapsules containing a color forming dye as a core substance and a color forming dye in a solid fine particle state that develops a color tone different from that of the dye contained in the microcapsules, but color separation The sex is insufficient. Japanese Patent Laid-Open No. 4-101885
In No. 6, a dye precursor and a microcapsule wall material are dissolved in a water-insoluble or insoluble organic solvent, emulsified and dispersed in a hydrophilic colloid solution, and then the system is heated and the pressure in the reaction vessel is reduced. By doing so, a manufacturing method for forming the walls of the microcapsules while distilling off the organic solvent is described. However, when the organic solvent is removed, complication of the process is unavoidable and the strength of the microcapsules is also reduced.

[0004]

The object of the present invention is to obtain a dye precursor composite which can be used for a multicolor thermosensitive recording medium by a simple method, and to prevent a mixture of a low temperature coloring color and a high temperature coloring color. It is an object of the present invention to provide a multicolor heat-sensitive recording material which is excellent in color separation and is also excellent in background color and scratch resistance.

[0005]

The above objects have been achieved by the present invention described below. That is, the present invention is a dye precursor complex in which a colorless or light-colored electron-donating dye precursor is coated with a resin film of a polyisocyanate compound, and the polyisocyanate compound is a water-dispersible polyisocyanate compound. The present invention relates to a dye precursor complex. The dye precursor composite of the present invention comprises, on a support, two or more kinds of colorless or light-colored electron-donating dye precursors each of which develops a different color tone, and an electron-accepting property of reacting with the dye precursor to form a color. In a multicolor thermosensitive recording medium having a thermosensitive coloring layer containing an organic compound provided on a support,
It can be used as at least one kind of the dye precursor. The present invention has been made to find that the objective can be achieved by coating an electron-donating dye precursor (hereinafter sometimes referred to as “dye precursor”) with a resin film of a water-dispersible polyisocyanate compound. is there. The reason why the present invention provides excellent color separation is not clear, but it is considered as follows. The water-dispersible polyisocyanate compound has a glass transition temperature higher than that of the normal dye precursor, so that by coating the dye precursor with the resin film of the water-dispersible polyisocyanate compound, the color development temperature shifts to the high temperature side. It is considered that the state becomes suitable as a dye precursor for high temperature color development, and the difference between the low temperature color tone and the high temperature color tone becomes clear. Further, in the conventional microcapsule, an oily solution in which a dye precursor and a polyisocyanate compound are dissolved is emulsified and dispersed in a protective colloid aqueous solution and heated to cause a polymerization reaction to form a capsule film. Therefore, the resin film of the polyisocyanate compound is formed from the inside of the capsule containing the dye precursor, but even if the polyisocyanate compound and the dye precursor are in a molten state, the glass transition point becomes low. On the other hand, the present invention is characterized in that the resin film is formed from the outside of the dye precursor, and since it is possible to maintain a high glass transition point, it is considered that excellent color separation properties can be obtained. .

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The dye precursor composite of the present invention is prepared by dispersing a dye precursor using a water-soluble polymer substance and then adding a water-dispersible polyisocyanate compound to the dispersion liquid to prepare a dye precursor. It is obtained by forming a resin film of polyisocyanate on the periphery. As the dye precursor used in the present invention, any of colorless and light-colored leuco dyes known in the conventional pressure-sensitive or thermal recording paper field can be used, and the triphenylmethane-based compound is not particularly limited. , Fluorane compounds, fluorene compounds, divinyl compounds and the like are preferable. Specific examples of typical dye precursors are shown below. These dye precursors may be used alone or in combination of two or more. <Triphenylmethane leuco dye> 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide [also known as crystal violet lactone] 3,3-bis (p-dimethylaminophenyl) phthalide [also known as malachite green] Lactone] <Fluoran-based leuco dye> 3-diethylamino-6-methylfluorane 3-diethylamino-6-methyl-7-anilinofluorane 3-diethylamino-6-methyl-7- (o, p-dimethylanilino) Fluorane 3-diethylamino-6-methyl-7-chlorofluorane 3-diethylamino-6-methyl-7- (m-trifluoromethylanilino) fluorane 3-diethylamino-6-methyl-7- (m-methylanilino) fluorane 3-diethylamino-6-methyl-7- (o-oct Loloanilino) fluorane 3-diethylamino-6-methyl-7- (p-chloroanilino) fluorane 3-diethylamino-6-methyl-7- (o-fluoroanilino) fluorane 3-diethylamino-6-methyl-7-n-octyl Anilinofluorane 3-diethylamino-6-methyl-7-n-octylaminofluorane

3-Diethylamino-6-methyl-7-benzylaminofluorane 3-diethylamino-6-methyl-7-dibenzylaminofluorane 3-diethylamino-6-chloro-7-methylfluorane 3-diethylamino-6 -Chloro-7-anilinofluorane 3-diethylamino-6-chloro-7-p-methylanilinofluorane 3-diethylamino-6-ethoxyethyl-7-anilinofluorane 3-diethylamino-7-methylfluorane 3-Diethylamino-7-dibenzylaminofluorane 3-diethylamino-6,8-dimethylfluorane 3-diethylamino-7-chlorofluorane 3-diethylamino-7- (m-trifluoromethylanilino) fluorane 3-diethylamino -7- (o-chloroanilino) fluorane -Diethylamino-7- (p-chloroanilino) fluorane 3-diethylamino-7- (o-fluoroanilino) fluorane 3-diethylamino-benzo [a] fluorane 3-diethylamino-benzo [c] fluorane 3-dibutylamino-6- Methyl-fluorane 3-dibutylamino-6-methyl-7-anilinofluorane 3-dibutylamino-6-methyl-7- (o, p-dimethylanilino) fluorane 3-dibutylamino-6-methyl-7- (O-Chloroanilino) fluorane 3-dibutylamino-6-methyl-7- (p-chloroanilino) fluorane 3-dibutylamino-6-methyl-7- (o-fluoroanilino) fluorane 3-dibutylamino-6-methyl -7- (m-trifluoromethylanilino) fluorane 3-dibutyl Mino-6-methyl-chlorofluorane 3-dibutylamino-6-methyl-7-bromofluorane 3-dibutylamino-6-ethoxyethyl-7-anilinofluorane 3-dibutylamino-6-chloro-7- Anilinofluorane 3-dibutylamino-6-methyl-7-p-methylanilinofluorane

3-dibutylamino-7- (o-chloroanilino) fluorane 3-dibutylamino-7- (o-fluoroanilino) fluorane 3-di-n-pentylamino-6-methyl-7-anilinofluorane 3-di-n-pentylamino-6-methyl-7- (p-
Chloroanilino) fluorane 3-di-n-pentylamino-7- (m-trifluoromethylanilino) fluorane 3-di-n-pentylamino-6-chloro-7-anilinofluorane 3-di-n-pentyl Amino-7- (p-chloroanilino) fluorane 3-pyrrolidino-6-methyl-7-anilinofluorane 3-piperidino-6-methyl-7-anilinofluorane 3- (N-methyl-N-propylamino) -6-Methyl-7-anilinofluorane 3- (N-methyl-N-cyclohexylamino) -6-
Methyl-7-anilinofluorane 3- (N-ethyl-N-cyclohexylamino) -6-
Methyl-7-anilinofluorane 3- (N-ethyl-N-xylamino) -6-methyl-
7- (p-chloroanilino) fluorane 3- (N-ethyl-p-toluidino) -6-methyl-
7-anilinofluorane 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluorane 3- (N-ethyl-N-isoamylamino) -6-chloro-7-anilino Fluorane 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane 3- (N-ethyl-N-isobutylamino) -6-methyl-7-anilinofluorane

3- (Np-tolyl-N-ethylamino) -7- (N-phenylmethyl-N-methyl) fluorane 3- (N-ethyl-N-ethoxypropylamino) -6
-Methyl-7-anilinofluorane 3-N-ethyl-N-isoamylamino-benzo [a]
Fluoran 3-N-ethyl-Np-methylphenylamino-7-
Methylfluorane 3-cyclohexylamino-6-chlorofluorane 2- (4-oxahexyl) -3-dimethylamino-6
-Methyl-7-anilinofluorane 2- (4-oxahexyl) -3-diethylamino-6
-Methyl-7-anilinofluorane 2- (4-oxahexyl) -3-dipropylamino-
6-methyl-7-anilinofluorane 2-methyl-6-p- (p-dimethylaminophenyl)
Aminoanilinofluorane 2-methoxy-6-p- (p-dimethylaminophenyl) aminoanilinofluorane 2-chloro-3-methyl-6-p- (p-phenylaminophenyl) aminoanilinofluorane 2 -Chloro-6-p- (p-dimethylaminophenyl)
Aminoanilinofluorane 2-nitro-6-p- (p-diethylaminophenyl)
Aminoanilinofluorane 2-amino-6-p- (p-diethylaminophenyl)
Aminoanilinofluorane 2-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluorane 2-phenyl-6-methyl-6-p- (p-phenylaminophenyl) aminoanilinofluorane

2-Benzyl-6-p- (p-phenylaminophenyl) aminoanilinofluorane 2-hydroxy-6-p- (p-phenylaminophenyl) aminoanilinofluorane 3-methyl-6-p -(P-dimethylaminophenyl)
Aminoanilinofluorane 3-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluorane 3-diethylamino-6-p- (p-dibutylaminophenyl) aminoanilinofluorane 2,4-dimethyl- 6-[(4-Dimethylamino) anilino] -fluorane <fluorene-based leuco dye> 3,6,6′-tris (dimethylamino) spiro [fluorene-9,3′-phthalide] 3,6,6′-tris (Diethylamino) spiro [fluorene-9,3'-phthalide] <Divinyl-based leuco dye> 3,3-bis- [2- (p-dimethylaminophenyl)
-2- (p-Methoxyphenyl) ethenyl] -4,5,
6,7-Tetrabromophthalide 3,3-bis- [2- (p-dimethylaminophenyl)
-2- (p-Methoxyphenyl) ethenyl] -4,5,
6,7-Tetrachlorophthalide 3,3-bis- [1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrabromophthalide 3,3- Bis- [1- (4-methoxyphenyl) -1-
(4-Pyrrolidinophenyl) ethylene-2-yl]-
4,5,6,7-tetrachlorophthalide

<Others> 3- (4-diethylamino-2-ethoxyphenyl)-
3- (1-ethyl-2-methylindol-3-yl)
-4-azaphthalide 3- (4-diethylamino-2-ethoxyphenyl)-
3- (1-octyl-2-methylindol-3-yl) -4-azaphthalide 3- (4-cyclohexylethylamino-2-methoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) ) -4-Azaphthalide 3,3-bis (1-ethyl-2-methylindole-3)
-Yl) phthalide 3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide 3,6-bis (diethylamino) fluorane-γ- (3
′ -Nitro) anilinolactam 3,6-bis (diethylamino) fluorane-γ- (4
′ -Nitro) anilinolactam 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2,
2-Dinitrileethane 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2-
β-naphthoylethane 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2,
2-Diacetylethanebis- [2,2,2 ', 2'-tetrakis- (p-dimethylaminophenyl) -ethenyl] -methylmalonic acid dimethyl ester

In the present invention, the water-soluble polymer substance used to disperse the dye precursor is an ionic polymer, a nonionic polymer such as gelatin, starch,
Carboxymethyl cellulose, polyvinyl alcohol,
Examples thereof include, but are not limited to, polyalkylbenzene sulfonate, polyoxyethylene sulfate, polycarboxylic acid, polycarboxylic acid salt, polyoxyalkyl ether and modified products thereof. The dispersion liquid in which the dye precursor is dispersed by using these water-soluble polymer substances has a particle diameter of the dye precursor of 50% by volume average of 0.1 μm to
It is desirable that the particles are atomized so as to be in the range of 1.0 μm, more preferably 0.3 μm to 0.8 μm. Finer particles are very effective in improving recording density and color separation. Further, instead of directly dispersing the dye precursor in the water-soluble polymer substance, a dye precursor dissolved in a low boiling point solvent such as ethyl acetate or dichloromethane, emulsified in the solution of the water-soluble polymer substance, After forming the emulsion,
It is also possible to volatilize the low boiling point solvent to obtain a dispersion liquid of the dye precursor. In the case of this method, since the obtained dispersion of the dye precursor becomes spherical, it becomes easy to be coated with the resin film of the water-dispersible polyisocyanate compound.

Next, a water-dispersible polyisocyanate compound and, if necessary, an auxiliary agent such as a polyol or polyamine are added to the dispersion liquid of the above dye precursor, and the mixture is added at 0.2 to 1.5 ° C.
The temperature is raised at a pace of / min and held while gently stirring to form a resin film of the water-dispersible polyisocyanate compound around the dye precursor. The water-dispersible polyisocyanate compound used in the present invention is mainly an aliphatic, alicyclic, or aromatic polyisocyanate compound or a derivative thereof, and is dispersed in water by adding a nonionic functional group such as ethylene oxide. It is the one that enhances sex. Examples of water-dispersible polyisocyanate compounds include, for example, Japanese Patent Publication No.
Reaction product of aliphatic polyisocyanate disclosed in JP-A-30160 and a monovalent or polyvalent nonionic polyalkylene ether alcohol containing at least one polyether chain having at least 10 ethylene oxide units. No. 7,109,327 and monohydric or polyhydric alcohols containing polyether chains containing an average of 7 to 25 alkylene oxide units, at least 70 mol% of which are ethylene oxide units, and 2,4- and / or Alternatively, a partially urethanized composition of 2,6-diisocyanatotoluene, JP-A-11-31070.
No. 0, which has an active hydrogen atom reactive with a polyisocyanate and an isocyanate group, has a hydrophilic / hydrophobic balance (HLB) of 17 or less, and has an average of 15 to 15 ethylene oxide units in one molecule. Examples thereof include modified polyisocyanates composed of a reaction product with 35 nonionic emulsifiers, but are not limited thereto.

The isocyanate used to obtain the water-dispersible polyisocyanate compound is mainly an aliphatic, alicyclic or aromatic polyisocyanate or a derivative thereof. Examples of the aliphatic and alicyclic polyisocyanates include: 1) Isocyanurate group-containing polyisocyanates based on aliphatic and / or alicyclic diisocyanates. 1,
6-diisocyanatohexane and / or 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (isophorone diisocyanate = IP
DI) based isocyanato isocyanurate. The production of such compounds is described, for example, in German Patent No. 2,616,416, European Patent Publication No. 3,765.
No. 10,589,47,452, U.S. Pat. No. 4,288,586 or 4,324,879. In addition, isocyanurate group-containing polyisocyanates based on other aliphatic and / or alicyclic diisocyanates represented by the following formula are also included. This is a simple tris-isocyanatoalkyl- (or -cycloalkyl-) isocyanurate or a mixture of it with its higher (containing more than one isocyanurate ring) homologue.

[0015]

[Chemical 1]

(In the formula, R ₁ , R ₂ , and R ₃ represent the same or different hydrocarbon groups obtained by removing the isocyanate group from the starting diisocyanate.) 2) Aliphatic group represented by the following formula And / or uretdione diisocyanate having an alicyclic bonded isocyanate group.

[0017]

[Chemical 2]

(In the formula, R ₁ and R ₂ are the same as above. In particular, they represent a hydrocarbon group obtained by removing an isocyanate group from hexamethylene diisocyanate and / or IPDI.) The uretdione diisocyanate may be used alone or otherwise. Can be present as a mixture with the aliphatic polyisocyanates mentioned above, in particular with the isocyanurate group-containing polyisocyanates described under 1) above.

3) Biuret group-containing polyisocyanates having aliphatically bonded isocyanate groups, ie tris- (6-isocyanatohexyl) -biuret or mixtures thereof with higher homologues thereof. 4) Polyisocyanates containing urethane groups and / or allophanate groups having aliphatically or cycloaliphatically bound isocyanate groups, ie excess hexamethylene diisocyanate or IPDI in a simple polyhydric alcohol (eg trimethylolpropane, glycerin, 1 , 2-dihydroxypropane or a mixture thereof). 5) An oxadiazinetrione group-containing polyisocyanate having an aliphatically or alicyclically bound isocyanate group represented by the following formula.

[0020]

[Chemical 3]

(Wherein R ₁ has the meaning already mentioned above, in particular the hexamethylene group when the product is formed from 1,6-diisocyanatohexane and carbon dioxide. The aliphatic or alicyclic polyisocyanates exemplified in 1) to 5) above can be present alone or in admixture as desired. In addition, the "aliphatic polyisocyanate" in the present invention represents a polyisocyanate in which the isocyanate is bonded to an aliphatic or alicyclic carbon atom. Further, examples of the aromatic polyisocyanate include 2,4-
And / or 2,6-diisocyanatotoluene and the like. Examples of the nonionic functional group such as ethylene oxide added to the polyisocyanate include ethylene oxide unit-containing polyether alcohol. For the preparation of suitable polyether alcohols, mono- or polyhydric initiator molecules such as methanol, n-butanol, cyclohexanol, 3-methyl-3-hydroxymethyloxetane, phenol, resorcinol, ethylene glycol, propylene glycol , Aniline,
Alkoxylation products of trimethylolpropane or glycerin (at least 10 generally 10-70, preferably 1
It contains at least one polyether chain containing 5 to 65 ethylene oxide units. ) Is used.

The water-dispersible polyisocyanate is produced by adding a hydrophilic compound containing an isocyanate-reactive group to the above-mentioned aliphatic, alicyclic or aromatic polyisocyanate or a derivative thereof, preferably the above-mentioned nonionic ethylene oxide. The unit-containing polyether alcohol is reacted at an NCO / OH equivalent ratio of at least about 1: 1, preferably about 2: 1 to about 1000: 1. An NCO / OH equivalent ratio of at least about 2: 1 is used, especially when using polyhydric polyether alcohols.
The production of the water-dispersible polyisocyanate is generally 50
It is carried out at a moderately high temperature of about 130 ° C. In the present invention, the amount of the water-dispersible polyisocyanate used for coating the dye precursor may be appropriately determined depending on the color development temperature required for the target multicolor heat-sensitive recording material, but 1 g of the dye precursor is used. On the other hand, by setting the amount to 0.03 to 0.7 g, and more preferably 0.1 to 0.5 g, a preferable color hue can be obtained.

Further, in addition to the water-dispersible polyisocyanate, it is possible to add a polyol, a polyamine or the like. Examples of the polyol include polyhydric alcohols and alkylene oxide adducts of polyhydric alcohols. Examples of polyhydric alcohols are ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,
4-butanediol, 1,5-pentanediol, 1,
6-hexanediol, resorcinol, glycerin,
Examples thereof include compounds having two or more hydroxyl groups such as diglycerin, trimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythritol, diglycerin, methyl glucoside, sorbitol and polysaccharides such as sucrose. As the polyamine, for example, ethylenediamine, propylenediamine, hexamethylenediamine, octamethylenediamine, paraphenylenediamine, piperazine, diethylenetriamine, triethylenetetramine, alkylenepolyamines such as tetraethylenepentamine, monoethanolamine, diethanolamine, triethanolamine, isopropanol. -Alkanolamines such as ruamine and isobutanolamine.

Further, in the present invention, it is possible to use commercially available polyurethane particles together with the water-dispersible polyisocyanate. This is a polyurethane particle having a particle diameter of 5 nm to 500 nm, preferably 10 nm to 200 nm. When used together with the above water-dispersible polyisocyanate, the polyurethane particle is cross-linked and the coverage with the dye precursor is improved. Examples of polyurethane particles include Takelac W series, Takelac WS series (manufactured by Mitsui Takeda Chemicals), and the like. The dye precursor composite coated with the resin film of the water-dispersible polyisocyanate compound obtained as described above is preferably used as a color-forming component which gives a high-temperature color-developing color tone of a multicolor thermosensitive recording medium. The multicolor thermosensitive recording medium of the present invention contains at least one dye precursor that develops a color tone different from that of the dye precursor contained in the dye precursor composite. These can be appropriately selected from various known dye precursors such as the above-mentioned dye precursors, but those that develop color at a lower temperature than the dye precursor composite are desirable. Further, these can be used by being dispersed in a form used in a general thermal recording material, that is, in a solid fine particle state. As the electron-accepting organic compound used in the multicolor thermosensitive recording medium of the present invention, an organic developer known in the thermosensitive recording field can be used.
Bisphenol A, 4-hydroxybenzoic acid esters, 4-hydroxyphthalic acid diesters, phthalic acid monoesters, bis- (hydroxyphenyl) described in JP-A-3-207688 and JP-A-5-24366. Sulfides, 4-hydroxyphenylarylsulfones, 4-hydroxyphenylarylsulfonates, 1,3-di [2- (hydroxyphenyl) -2
-Propyl] -benzenes, 4-hydroxybenzoyloxybenzoic acid ester, bisphenol sulfones,
Examples thereof include aminobenzenesulfonamide derivatives described in JP-A-8-59603 and diphenylsulfone cross-linking compounds described in International Publication WO97 / 16420. Specific examples of typical known color developing agents are shown below, but the invention is not particularly limited thereto. Further, these color developing agents may be used alone or in combination of two or more kinds.

<Bisphenol A>4,4'-isopropylidene diphenol (also known as bisphenol A) 4,4'-cyclohexylidene diphenol p, p '-(1-methyl-normal hexylidene) diphenol 1, 7-di (hydroxyphenylthio) -3,5-dioxaheptane <4-hydroxybenzoic acid esters> benzyl 4-hydroxybenzoate 4-hydroxybenzoate ethyl 4-hydroxybenzoate propyl 4-hydroxybenzoate isopropyl 4 -Butyl hydroxybenzoate 4-Hydroxybenzoic acid isobutyl 4-hydroxybenzoic acid methylbenzyl <4-hydroxyphthalic acid diesters> 4-hydroxyphthalic acid dimethyl 4-hydroxyphthalic acid diisopropyl 4-hydroxyphthalic acid dibenzyl 4-hydroxyphthalic acid Dihexyl acid <Phthalic acid monoesters> Phthalic acid monobenzyl ester Phthalic acid monocyclohexyl ester Phthalic acid monophenyl ester Phthalic acid monomethyl phenyl ester Phthalic acid monoethyl phenyl ester Phthalic acid monopropyl benzyl ester Phthalic acid monohalogen benzyl ester Phthalic acid mono Ethoxybenzyl ester <bis- (hydroxyphenyl) sulfides> Bis- (4-hydroxy-3-tert-butyl-6-
Methylphenyl) sulfide bis- (4-hydroxy-2,5-dimethylphenyl)
Sulfide bis- (4-hydroxy-2-methyl-5-ethylphenyl) sulfide bis- (4-hydroxy-2-methyl-5-isopropylphenyl) sulfide bis- (4-hydroxy-2,3-dimethylphenyl)
Sulfide bis- (4-hydroxy-2,5-dimethylphenyl)
Sulfide bis- (4-hydroxy-2,5-diisopropylphenyl) sulfide bis- (4-hydroxy-2,3,6-trimethylphenyl) sulfide bis- (2,4,5-trihydroxyphenyl) sulfide bis- ( 4-hydroxy-2-cyclohexyl-5-methylphenyl) sulfide bis- (2,3,4-trihydroxyphenyl) sulfide bis- (4,5-dihydroxy-2-tert-butylphenyl) sulfide bis- (4- Hydroxy-2,5
-Diphenylphenyl) sulfide bis- (4-hydroxy-2-tert-octyl-5
-Methylphenyl) sulfide

<4-Hydroxyphenylarylsulfones>4-hydroxy-4'-isopropoxydiphenylsulfone4-hydroxy-4'-n-propoxydiphenylsulfone4-hydroxy-4'-n-butyloxydiphenylsulfone<4-Hydroxyphenylarylsulfonates> 4-hydroxyphenylbenzenesulfonate 4-hydroxyphenyl-p-tolylsulfonate 4-hydroxyphenylmethylenesulfonate 4-hydroxyphenyl-p-chlorobenzenesulfonate 4-hydroxyphenyl-p- tert-Butylbenzenesulfonate 4-hydroxyphenyl-p-isopropoxybenzenesulfonate 4-hydroxyphenyl-1'-naphthalenesulfonate 4-hydroxyphenyl-2'-naphth Phosphorus sulfonate <1,3-di [2- (hydroxyphenyl) -2-propyl] benzenes> 1,3-di [2- (4-hydroxyphenyl) -2-propyl] benzene 1,3-di [ 2- (4-Hydroxy-3-alkylphenyl) -2-propyl] benzene 1,3-di [2- (2,4-dihydroxyphenyl)-
2-propyl] benzene 1,3-di [2- (2-hydroxy-5-methylphenyl) -2-propyl] benzene <resorcinols> 1,3-dihydroxy-6 (α, α-dimethylbenzyl) -benzene

<4-Hydroxybenzoyloxybenzoate> Benzyl 4-hydroxybenzoyloxybenzoate 4-Hydroxybenzoyloxymethyl benzoate 4-Hydroxybenzoyloxyethyl benzoate 4-Hydroxybenzoyloxypropyl propyl 4-hydroxybenzoyloxy Butyl benzoate 4-hydroxybenzoyloxy isopropyl 4-hydroxybenzoyloxy benzoate tert-butyl 4-hydroxybenzoyloxy hexyl benzoate 4-hydroxybenzoyloxy octyl 4-hydroxybenzoyloxy benzoate Nonyl 4-hydroxybenzoyloxy benzoate Cyclohexyl benzoate 4-hydroxybenzoyloxy β-phenethyl 4-hydroxybenzoyloxy benzoate Phenyl 4-hydroxybenzoyloxybenzoic acid α-naphthyl 4-hydroxybenzoyloxybenzoic acid β-naphthyl 4-hydroxybenzoyloxy sec-butyl benzoate

<Bisphenol Sulfones (I)> Bis- (3-1-butyl-4-hydroxy-6-methylphenyl) sulfone Bis- (3-ethyl-4-hydroxyphenyl) sulfone Bis- (3-propyl-4-) Hydroxyphenyl) sulfone bis- (3-methyl-4-hydroxyphenyl) sulfone bis- (2-isopropyl-4-hydroxyphenyl)
Sulfone bis- (2-ethyl-4-hydroxyphenyl) sulfone bis- (3-chloro-4-hydroxyphenyl) sulfone bis- (2,3-dimethyl-4-hydroxyphenyl)
Sulfone bis- (2,5-dimethyl-4-hydroxyphenyl)
Sulfone bis- (3-methoxy-4-hydroxyphenyl) sulfone 4-hydroxyphenyl-2'-ethyl-4'-hydroxyphenyl sulfone 4-hydroxyphenyl-2'-isopropyl-4'-
Hydroxyphenyl sulfone 4-hydroxyphenyl-3'-isopropyl-4'-
Hydroxyphenyl sulfone 4-hydroxyphenyl-3'-sec butyl-4'-
Hydroxyphenyl sulfone 3-chloro-4-hydroxyphenyl-3'-isopropyl-4'-hydroxyphenyl sulfone 2-hydroxy-5-t-butylphenyl-4'-hydroxyphenyl sulfone 2-hydroxy-5-t-aminophenyl -4'-hydroxyphenyl sulfone 2-hydroxy-5-t-isopropylphenyl-4 '
-Hydroxyphenyl sulfone 2-hydroxy-5-t-octylphenyl-4'-hydroxyphenyl sulfone 2-hydroxy-5-t-butylphenyl-3'-chloro-4'-hydroxyphenyl sulfone 2-hydroxy-5-t -Butylphenyl-3'-methyl-4'-hydroxyphenyl sulfone 2-hydroxy-5-t-butylphenyl-3'-isopropyl-4'-hydroxyphenyl sulfone 2-hydroxy-5-t-butylphenyl-2 '-Methyl-4'-hydroxyphenyl sulfone

<Bisphenolsulfones (II)>4,4'-sulfonyldiphenol2,4'-sulfonyldiphenol3,3'-dichloro-4,4'-sulfonyldiphenol3,3'-dibromo-4 , 4'-Sulfonyldiphenol 3,3 ', 5,5'-Tetrabromo-4,4'-sulfonyldiphenol 3,3'-Diamino-4,4'-sulfonyldiphenol <Others> p-tert-butylphenol 2,4-Dihydroxybenzophenone novolac type phenol resin 4-hydroxyacetophenone p-phenylphenol benzyl-4-hydroxyphenylacetate p-benzylphenol 4,4′-bis (p-tolylsulfonylaminocarbonylamino) diphenylmethane 4,4′- Bis (phenylaminothiocarbonyla No.) diphenyl sulfide In addition to this, a metal chelate-type color-forming component such as a higher fatty acid metal double salt described in JP-A-10-258577 and a polyvalent hydroxyaromatic compound is formed in a color tone different from that of the dye precursor complex. Can also be used as

In the present invention, conventionally known sensitizers may be blended to adjust the recording sensitivity as long as the desired effects for the above problems are not impaired. Such sensitizers include stearic acid amide, palmitic acid amide, methoxycarbonyl-N-stearic acid benzamide, N-
Benzoylstearic acid amide, N-eicosanoic acid amide, ethylenebisstearic acid amide, behenic acid amide, methylenebisstearic acid amide, methylolamide, N-methylolstearic acid amide, dibenzyl terephthalate, dimethyl terephthalate, dioctyl terephthalate, Benzyl p-benzyloxybenzoate, 1-
Phenyl hydroxy-2-naphthoate, dibenzyl oxalate, oxalic acid-di-p-methylbenzyl, oxalic acid-
Di-p-chlorobenzyl, 2-naphthylbenzyl ether, m-terphenyl, p-benzyl biphenyl, 4-
Biphenyl paratolyl 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-acetotoluidide, p-acetophenene Tizide, N-acetoacetyl-p-toluidine, di (β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1-isopropylphenyl-2-phenylethane, 1,2-bis (phenoxymethyl) Examples thereof include benzene, p-toluenesulfonamide, o-toluenesulfonamide, di-p-tolylcarbonate, phenyl-α-naphthylcarbonate, but are not particularly limited thereto. You may use these sensitizers individually or in mixture of 2 or more types.

As the binder used in the present invention, a completely saponified polyvinyl alcohol having a polymerization degree of 200 to 1900, a partially saponified polyvinyl alcohol, a carboxy modified polyvinyl alcohol, an amide modified polyvinyl alcohol, a sulfonic acid modified polyvinyl alcohol, and a butyral modified polyvinyl are used. Modified polyvinyl alcohol such as alcohol, cellulose derivative such as hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, acetyl cellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer, polyvinyl chloride, polyvinyl acetate, polyacrylamide , Polyacrylic acid ester, polyvinyl butyral, polystyrene and their copolymers, polyamide resin, silicone Butter, petroleum resins, terpene resins, ketone resins, and coumarone resins. These polymeric substances are water, alcohols, ketones, esters,
In addition to being used by being dissolved in a solvent such as a hydrocarbon, it may be used in a state of being emulsified in water or another medium or dispersed in a paste form, and may be used together depending on the required quality. Examples of the filler that can be used in the present invention include silica, calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, titanium oxide, zinc oxide, aluminum hydroxide, polystyrene resin, urea-formalin resin, styrene-methacrylic acid copolymer. Polymer, styrene-butadiene copolymer,
Examples include inorganic or organic fillers such as hollow plastic pigments.

In order to obtain a more vivid color tone at high temperature, in the case of a multi-layer type, it is effective to reduce the amount of the filler in the high temperature color-forming layer or not to add it. This is because, in the case of a color-added type, the color-forming composition (reaction product of the dye precursor and the developer, that is, color-developed image) formed in the high-temperature color-developing layer during high-temperature heating is not limited to the high-temperature color-developing layer and is low in temperature. This is probably because the filler in the color forming layer is easily absorbed, and the high temperature color tone, which is a mixed color, is obtained by efficiently mixing with the low temperature color forming composition. In addition, release agents such as fatty acid metal salts, lubricants such as waxes, benzophenone-based and triazole-based UV absorbers, waterproofing agents such as glyoxal, dispersants, defoamers, antioxidants, fluorescent dyes, etc. Can be used. As the support, paper, recycled paper, synthetic paper, plastic film, foamed plastic film, non-woven fabric, metal foil or the like can be used, and a composite sheet in which these are combined may be used. further,
An overcoat layer of a polymer substance or the like may be provided on the thermosensitive color developing layer for the purpose of enhancing scratch resistance. Further, an undercoat layer containing an organic filler or an inorganic filler may be provided between the thermosensitive color developing layer and the support for the purpose of increasing the color developing sensitivity. The amount of the organic developer, dye precursor, dye precursor complex, and other various components used in the multicolor thermosensitive recording medium of the present invention, and the types and amounts of various other components are determined according to the required performance and recording suitability, and in particular, Although not limited, normally, 0 to 4 parts of the filler and 1 to 5% of the total solid content of the binder are suitable for 1 part of the color developer. It is preferred that the dye precursor is contained in the composite or in the non-composite content in an amount of 0.1 to 2 parts per 1 part of the color developer.

In the present invention, the coating amount of the thermosensitive color developing layer is not particularly limited, but is generally 1.5 by dry weight.
It is adjusted in the range of about 12 g / m ² . Further, in the present invention, in the case of a multi-layer type, it is possible to provide an intermediate layer between the high temperature color developing layer and the low temperature color developing layer. The above-described binder, filler, sensitizer, defoaming agent, ultraviolet absorber, fluorescent dye and the like can be appropriately incorporated into the coating liquid for forming the intermediate layer. Further, the coating amount of the intermediate layer may be adjusted within the range of about 1 to 10 g / m ² .
These developers, dye precursor composites, and materials to be added as necessary are atomized by a crusher such as a ball mill, attritor, or sand grinder or a suitable emulsifying device to a particle size of several microns or less, A binder and various additive materials are added depending on the purpose to prepare a coating liquid. As the coating method, hand coating, size press coater method, roll coater method, air knife coater method, blend coater method, flow coater method, curtain coater method, comma direct method, gravure direct method, gravure reverse method, reverse roll coater method Etc. Moreover, you may dry after spraying, spraying, or immersion.

[0034]

EXAMPLES Examples of the present invention will be shown below, but the scope of the present invention is not limited thereto. In Examples and Comparative Examples, parts and% indicate parts by weight and% by weight, respectively.

Example 1 <Preparation of Dye Precursor Coated with Resin Film of Water-Dispersible Polyisocyanate> 3- (N-ethyl-) was added to 80.0 parts of 8% polyvinyl alcohol aqueous solution.
20.0 parts of N-isoamylamino) -6-methyl-7-anilinofluorane are mixed and wet-milled with a sand grinder until the 50% volume particle diameter of the above particles becomes 0.5 μm, and dispersed. Liquid A was obtained. Dispersion A-50 parts with water 4
6.6 parts and 0.4 parts of glycerin were added and stirred, and then kept at 35 ° C., 3 parts of a water-dispersible polyisocyanate (trade name WD730: manufactured by Mitsui Takeda Chemical Co., Ltd.) in which ethylene oxide units were added to isocyanurate polyisocyanate. 8 at a pace of 0.2-1.5 ° C / min after addition of
The temperature was raised to 0 ° C. and kept for 10 hours and then cooled to 30 ° C. to obtain a dye precursor dispersion B (dye concentration 10.0%) coated with a resin film of a water-dispersible polyisocyanate. <Manufacture of multicolor thermosensitive recording medium> A developer dispersion (liquid) for the thermosensitive coloring layer and a leuco dye dispersion (liquid) that develops a blue color having the following composition are separately prepared with a sand grinder to have an average particle diameter of 1 Wet milling was done to micron. Liquid (developer dispersion liquid) 4-hydroxy-4'-isopropoxydiphenyl sulfone 6.0 parts 10% polyvinyl alcohol 18.8 parts water 11.2 parts liquid (blue leuco dye dispersion liquid) 3,3-bis (P-Dimethylaminophenyl) -6-dimethyl aminophthalide 1.0 part 10% Polyvinyl alcohol 2.3 parts Water 1.3 parts The dispersions were mixed and stirred at the following ratios to prepare a thermosensitive color developing layer coating liquid. . Liquid (developer dispersion liquid) 48.0 parts Liquid (blue leuco dye dispersion liquid) 9.2 parts Dye precursor dispersion liquid B 20.0 parts Silicon oxide pigment (25% dispersion liquid; Mizukasil P-527 (Mizuzawa) Chemical)) 40 parts 10% polyvinyl alcohol 12.4 parts The adjusted thermosensitive coloring layer coating solution is applied to one side of a base paper of 50 g / m ^{2 so} that the coating amount is 5.0 g / m ^2, and then dried. Then, this sheet was processed with a super calender so that the smoothness was 500 to 600 seconds to obtain a multicolor thermosensitive recording material.

[Example 2] 46 parts of water was added to 50 parts of dispersion A.
To 52 parts and 0.48 parts of tetraethylenepentamine were added and stirred and then held at 35 ° C., 3 parts of a water-dispersible polyisocyanate (WD730: manufactured by Mitsui Takeda Chemical Co., Ltd.) in which ethylene oxide unit was added to isocyanurate polyisocyanate was added. A dye precursor dispersion C coated with a resin film of a water-dispersible polyisocyanate was obtained in the same manner as in Example 1 except that the addition was performed. Furthermore, this dispersion C
A multicolor thermosensitive recording medium was prepared in the same manner as in Example 1 except that was used instead of the dye precursor dispersion liquid B.

Example 3 Water-dispersible polyisocyanate obtained by adding ethylene oxide unit to isocyanurate polyisocyanate (WD730: Mitsui Takeda) was added to 50 parts of Dispersion A-50 parts of water and kept at 35 ° C. A dye precursor dispersion D coated with a resin film of a water-dispersible polyisocyanate was obtained in the same manner as in Example 1 except that 3 parts of Chemical) was added. Furthermore, except that this dispersion D is used instead of the dye precursor dispersion B,
A multicolor thermosensitive recording medium was prepared in the same manner as in Example 1.

Example 4 To 50 parts of Dispersion A was added 44 parts of water and 4 parts of a 30% aqueous solution of polyurethane particles having an average particle size of 60 μm (W-615: manufactured by Mitsui Takeda Chemical Co., Ltd.), and the mixture was heated to 35 ° C. Water-dispersible polyisocyanate was prepared in the same manner as in Example 1 except that 2 parts of water-dispersible polyisocyanate (WD730: manufactured by Mitsui Takeda Chemical Co., Ltd.) in which ethylene oxide units were added to isocyanurate-type polyisocyanate was added to the retained product. A dye precursor dispersion E coated with the resin film of was obtained. Further, a multicolor thermosensitive recording medium was prepared in the same manner as in Example 1 except that this dispersion liquid E was used instead of the dye precursor dispersion liquid B.

Comparative Example 1 A multicolor thermosensitive recording medium was prepared in the same manner as in Example 1. However, in the preparation of the heat-sensitive color developing layer coating liquid, 9.2 parts of the black dye dispersion liquid (liquid) which had been wet ground with the following composition was added instead of the dye precursor B liquid. Liquid (black leuco dye dispersion) 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluorane 1.0 part 10% polyvinyl alcohol 2.3 parts water 1.3 parts

[Comparative Example 2] 15.0 parts of 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluorane was added to 30.0 parts of diisopropylnaphthalene and dissolved by heating to 35 ° C. The mixture was allowed to cool, 36.0 parts of dicyclohexylmethane-4,4'-diisocyanate was added and stirred, and the resulting mixture was added to 64.0 parts of a 5.5% PVA aqueous solution and vigorously stirred to emulsify. O / W with an average particle diameter of 1.5 μm
After obtaining a type emulsion, 105.0 parts of water was mixed with this emulsion, and the mixture was held at 80 ° C. for 10 hours while stirring extremely gently to obtain a urethane precursor microcapsule dispersion liquid F of a dye precursor. A multicolor thermosensitive recording medium was prepared in the same manner as in Example 1 except that 49.1 parts of this dispersion liquid F was used instead of 29.4 parts of the dye precursor dispersion liquid B.

[Evaluation Method] The multicolor thermosensitive recording medium obtained as described above was tested as follows, and the results are shown in Table 1.・ Color development For multicolor thermosensitive recording media, thermal printer manufactured by MARKPOINT (thermal head manufactured by ROHN, KM2004-
A3 attached), applied energy 0.076 mj /
Printing was performed at dot and 0.219 mj / dot, and the obtained image and background were measured using a Macbeth densitometer (RD-914). In the case of evaluating a blue color image, the difference between the values measured by the red filter (R) and the blue filter (B) of a Macbeth densitometer is used. When evaluating a black color image and the background, an amber filter (A) is used. It was expressed by the value measured in. Color separation property The thermosensitive recording materials obtained in Examples and Comparative Examples were blown by a writer's fire from the surface opposite to the surface provided with the thermosensitive recording layer, and the state of the central portion and the peripheral portion of the color-developed portion which spreads in a round and irregular shape Was visually determined. Since the central portion of the color-developing portion has a high temperature, it has a high-temperature coloring color tone, and the peripheral portion has a low temperature, and thus has a low-temperature coloring color tone. ○: The boundary between the black color of the high-temperature color tone and the blue color of the low-temperature color tone is clear △: The boundary is blurred or blurred ×: The boundary is difficult to distinguish

[0042]

[Table 1]

[Evaluation Results] In the examples of the present invention, sufficient recording density and clear color tone were obtained at low applied energy (0.076 mj / dot) and high applied energy (0.219 mj / dot). On the other hand, in Comparative Example 1 in which two kinds of dye precursors that develop different color tones were mixed, it was not possible to obtain a multicolor thermosensitive recording material that develops different color tones depending on the applied energy. Further, the examples of the present invention have a clear color tone difference due to the temperature difference and are excellent in color separability, whereas the comparative example has an unclear boundary between the black color of the high temperature color tone and the blue color of the low temperature color tone. It was

[0044]

According to the present invention, a multicolor thermosensitive recording medium having high recording density in each color tone can be obtained. In particular,
Even in the case where the same thermosensitive coloring layer contains dye precursors that develop different color tones, a recorded image having a clear color tone can be obtained, which is extremely useful.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshihide Kimura             5-21-1 Oji, Kita-ku, Tokyo Nippon Paper Industries             Product Research Institute Co., Ltd. F term (reference) 2H026 AA11 AA28 BB01 BB21 CC05                       EE05 FF05 FF07                 4G005 AA01 AB14 BA02 DA05W                       DB27X DC42Y DC46Y DD24Y                       DD38Z EA08

Claims (3)

[Claims] 1. A dye precursor composite in which a colorless to light-colored electron-donating dye precursor is coated with a resin film of a water-dispersible polyisocyanate compound. 2. A support comprising two or more kinds of colorless or light-colored electron-donating dye precursors each of which develops a different color tone, and an electron-accepting organic compound which reacts with the dye precursor to develop a color. A multicolor thermosensitive recording medium comprising a thermosensitive coloring layer on a support, wherein at least one of the dye precursors is the dye precursor composite according to claim 1. 3. A method for producing a dye precursor complex in which a colorless or light-colored electron-donating dye precursor is coated with a resin film of a water-dispersible polyisocyanate compound, wherein a water-soluble polymer substance is used. A method for producing a dye precursor complex, comprising dispersing the dye precursor, adding a water-dispersible polyisocyanate compound to the dispersion, and forming a resin film of the polyisocyanate compound around the dye precursor.