JP2002011959A - Multi-color heat sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-color heat sensitive recording material having good color separating of a low temperature color (red color) and a high temperature color (black color), high resolution originating from color bleeding and good image preservability. SOLUTION: In the multi-color heat sensitive recording material comprising a heat sensitive recording layer containing two types or more of electron donative dye precursors for color developing in different color tones and one or more types of developers for color developing the precursor at a heating time, the precursor contains (1) one or more types of dye precursor dispersion particles for color developing in a red color, and (2) one or more types of dye precursors for color developing in a black color having a color developing regulating layer obtained by addition polymerizing a vinyl monomer, and at least one of the recording layer and a protective layer provided on the recording layer is colored in a pale blue or pale green color by a coloring agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor heat-sensitive recording material which develops different colors depending on different heating conditions such as color temperature. More specifically, it is a multicolor heat-sensitive material that develops a reddish color at low temperatures and a blackish color by mixing with low-temperature colors at high temperatures, with good color separation, no color bleeding at high temperatures, and good image storability. Related to recording materials.

[0002]

2. Description of the Related Art A thermosensitive recording material generally comprises a support provided with a thermosensitive recording layer mainly composed of an electron-donating, usually colorless or pale-colored dye precursor and an electron-accepting developer.
By heating with a thermal head, hot pen, laser light, etc., the dye precursor and the developer react instantaneously to obtain a colored image, the recording device is simple and easy to maintain, and noise is generated. Measurement recorder, facsimile, printer, computer terminal, PO
It is used in a wide range of fields, such as S label machines and ticket vending machines.

With the diversification of uses of such heat-sensitive recording materials, a multicolor heat-sensitive recording material capable of developing two or more colors depending on the heating temperature is desired. There have been many proposals for two-color heat-sensitive recording paper, which is highly practicable, and has good color separation, represented by two-color heat-sensitive recording paper represented by a color that develops a black color at high temperatures.

[0004] As a typical method for realizing such multicolored thermal recording, a method of providing two or more thermosensitive layers is as follows.
(1) A method in which dye precursors that form colors different from each other are classified into a high-temperature coloring layer and a low-temperature coloring layer, and a color mixture of a low-temperature hue and a high-temperature hue is obtained during high-temperature printing following low-temperature coloring (
54-097048). In this method, although the high-temperature coloring layer and the low-temperature coloring layer are separated, the color separation is improved,
Color mixing with a low-temperature color (red color) during high-temperature (black color) printing was inevitable, and the color became reddish black, and color separation was still insufficient.
In order to improve this color separation, (2) dye precursors that form colors different from each other are stratified into a high-temperature coloring layer and a low-temperature coloring layer via a decoloring agent layer, and at the time of high-temperature printing following low-temperature printing, Method of printing while erasing the low-temperature coloring layer
-139470, JP-A-57-178791). In this method, the color separation is very good because the low-temperature color is erased during high-temperature coloring, but the presence of the decoloring agent in the heat-sensitive layer raises concerns about the long-term storage of images. There is still a disadvantage that the production cost is high.

On the other hand, as a method for obtaining two colors having good color separation with a single layer of the heat-sensitive layer, (3) a plurality of dye precursors which develop colors different from each other are contained in the same layer, and at least There is a method of encapsulating one type in a microcapsule (Japanese Patent Laid-Open No. 8-282115). In this method, color separation is good because the dye precursors are isolated from each other by the capsule membrane, but since the oily liquid is encapsulated in the microcapsules, the capsules are destroyed by the pressure and friction during handling and the background coloration There are drawbacks that occur.

Further, (4) a method in which a high-temperature coloring dye precursor is formed into composite fine particles of at least one polymer substance selected from polyurea and polyurethane, and is used in combination with solid fine particles of a low-temperature dye precursor (Japanese Patent Application Laid-Open No. 9-1997). No. 142025) has also been proposed. In this method, in order to completely cover the dye precursor, a large amount of polyurea or polyurethane is contained, and color separation is good, but there is a difficulty in insufficient color development sensitivity. Further, (5) a method of covering at least one or more of two or more dye precursors that develop colors with different color tones with a color control layer polymerized with a compound having an unsaturated carbon bond (JP-A-11-311)
No. 01118) has been proposed by the present applicant. In this method, the dye precursor particles are covered with a thin polymer film (color-controlling layer), so that the color-forming sensitivity can be easily adjusted, and color separation can be controlled by the color-controlling layer. In this case, there is a defect that color fringing occurs, which is a phenomenon in which the periphery of a character is surrounded by a low-temperature color, and the image lacks sharpness.

[0007]

An object of the present invention is to provide good color separation between a low-temperature color (red color) and a high-temperature color (black color).
An object of the present invention is to provide a multicolor heat-sensitive recording material having a high resolution derived from color bleeding and good image storability.

[0008]

The object of the present invention is to provide at least two kinds of electron-donating dye precursors having different color tones on a support, and at least one type of developer for coloring the dye precursors upon heating. A multicolor heat-sensitive recording material having a heat-sensitive recording layer containing a coloring agent, wherein the dye precursor comprises: 1) one or more dye precursor-dispersed particles emitting a reddish color; and 2) a vinyl monomer. The heat-sensitive recording layer is formed of one or more dye precursors which are obtained by addition polymerization and have a color control layer, and which develops a black color having a black color on the surface. This was achieved by coloring in a series color.
Further, when high preservability of the recorded image is required, one or more protective layers are laminated on the heat-sensitive recording layer, and at least one of the heat-sensitive recording layer and the protective layer is lightened with a coloring agent. The above-mentioned object has been achieved by coloring a bluish color or a pale greenish color.

Further, by using a phthalocyanine-based organic pigment as the coloring agent, the long-term preservability of the background is improved, and by using 3-diethylamino-7-chlorofluorane as the dye precursor, high sensitivity and color bleeding can be achieved. No multicolor heat-sensitive recording material was obtained. Furthermore, the red discoloration of the heat-sensitive surface background that occurs when a magnetic recording layer is provided on the back surface of the support is improved by the addition of a coloring agent, and the printed characters are multicolor thermosensitive magnetic recording materials having a visually vivid resolution. was gotten.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As a constituent material of a heat-sensitive recording layer,
One or more dye precursor dispersed particles that develop a reddish color, and one or more dye precursors that develop a blackish color having a coloration control layer obtained by addition polymerization of a vinyl monomer on the surface; , One or more developers for coloring these dye precursors when heated, and a colorant capable of coloring pale blue or pale green, etc. as main components. A known binder, a sensitizer, an oil-absorbing white pigment, a surfactant and the like are added, and the composition is coated on a support.
Further, in order to impart chemical resistance, a protective layer is provided on the heat-sensitive recording layer, and a coloring agent is added to at least one of the heat-sensitive recording layer and the protective layer. A support having a magnetic recording layer provided on the back surface is also used.

The dispersion of the dye precursor in the present invention can be obtained by dry-milling or wet-milling a dye precursor known in the field of heat-sensitive recording materials. As a method of pulverization, generally, water is used as a dispersion medium and dispersed using an arbitrary method such as a sand mill or a ball mill, and the particle size of the dispersed particles is 0.1 μm or more and 10 μm or less, preferably 0.3 μm or less.
m or more and 2 μm or less. When the thickness is smaller than 0.1 μm, the red coloring dye precursor has a background fog when a heat-sensitive recording material is used, while the black coloring dye precursor provided with a color development controlling layer is difficult to form a color development controlling layer. On the other hand, if the particle size of the dispersed particles is larger than 10 μm, the coloring sensitivity of both the red and black coloring dye precursors deteriorates, which is not preferable.

Here, specific examples of the red coloring dye precursor include the following, but the present invention is not limited thereto. 3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide,
3,3-bis (1-n-butyl-2-methylindol-3-yl) tetrachlorophthalide, 3,3-bis (1
-N-butylindol-3-yl) phthalide, 3,3
-Bis (1-n-pentyl-2-methylindole-3
-Yl) phthalide, 3,3-bis (1-n-hexyl-
2-methylindol-3-yl) phthalide, 3,3-
Bis (1-n-octyl-2-methylindole-3-
Yl) phthalide, 3,3-bis (1-methyl-2-methylindol-3-yl) phthalide, 3,3-bis (1
-Ethyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-propyl-2-methylindol-3-yl) phthalide, 3,3-bis (2-methylindol-3-yl) phthalide , Rhodamine B-anilinolactam, rhodamine B- (o-chloroanilino) lactam, rhodamine B- (p-nitroanilino) lactam, 3-diethylamino-5-methyl-7-dibenzylaminofluoran, 3-diethylamino-6- Methyl-
7-chlorofluorane, 3-diethylamino-6-methoxyfluoran, 3-diethylamino-6-methylfluoran, 3-diethylamino-6-methyl-7-chloro-8-benzylfluoran, 3-diethylamino-6
7-dimethylfluoran, 3-diethylamino-6,8
-Dimethylfluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-7-methoxyfluoran, 3-diethylamino-7- (N-acetyl-N
-Methyl) aminofluoran, 3-diethylamino-7
-Methylfluoran, 3-diethylamino-7-methylethoxyfluoran, 3-diethylamino-7-p-methylphenylfluoran, 3-diethylamino-7,8
-Benzofluoran, 3-diethylaminobenzo [a]
Fluoran, 3-diethylaminobenzo [c] fluoran, 3-dimethylamino-7-methoxyfluoran, 3
-Dimethylamino-6-methyl-7-chlorofluoran, 3-dimethylamino-7-methylfluoran, 3-
Dimethylamino-7-chlorofluorane, 3- (N-ethyl-p-toluidino) -7-methylfluoran, 3-
(N-ethyl-N-isoamyl) amino-6-methyl-
7-chlorofluorane, 3- (N-ethyl-N-isoamyl) amino-7,8-benzofluoran, 3- (N-
Ethyl-N-isoamyl) amino-7-methylfluoran, 3- (N-ethyl-Nn-octyl) amino-6
-Methyl-7-chlorofluoran, 3- (N-ethyl-
Nn-octyl) amino-7,8-benzofluoran, 3- (N-ethyl-Nn-octyl) amino-7
-Methylfluorane, 3- (N-ethyl-NNn-octyl) amino-7-chlorofluorane, 3- (N-ethyl-N-4-methylphenyl) amino-7,8-benzofluoran, 3- (N-ethyl-N-4-methylphenyl) amino-7-methylfluoran, 3- (N-isopentyl-N-ethyl) amino-7,8-benzofluoran, 3- (N-ethoxyethyl -N-ethyl) amino-
7,8-benzofluoran, 3- (N-ethoxyethyl-N-ethyl) amino-7-chlorofluoran, 3-n
-Dibutylamino-6-methyl-7-chlorofluorane, 3-n-dibutylamino-7,8-benzofluoran, 3-n-dibutylamino-7-chlorofluoran,
3-n-dibutylamino-7-methylfluoran, 3-
Diallylamino-7,8-benzofluorane, 3-diallylamino-7-chlorofluorane, 3-di-n-butylamino-6-methyl-7-bromofluorane, 3-cyclohexylamino-6-chlorofluorane Oran, 3-pyrrolidylamino-7-methylfluoran, 3-ethylamino-7-methylfluoran, 3-diethylamino-benzo [a] fluoran, 3-N-ethyl-N-isoamylamino-benzo [a] Fluoran, 3-N-ethyl-N
-P-methylphenylamino-7-methylfluoran,
3-dibutylamino-6-methyl-7-bromofluorane, 3,6-bis (diethylaminofluoran) -γ-
(4'-nitro) anilinolactam.

Among these red color dye precursors, 3-diethylamino-6-methyl-7-chlorofluoran,
Diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluoran, 3-N-ethyl-N-
p-Methylphenylamino-7-methylfluoran is a red color close to vermilion and is particularly preferably used. In particular, in the present invention, 3-diethylamino-7-chlorofluorane has good color-forming sensitivity, color separation and color bleeding. Surface was good.

Next, specific examples of the black color dye precursor include 3-dibutylamino-6-methyl-7-anilinofluoran and 3-dibutylamino-6-methyl-7-phenylaminofluoran. , 3-dibutylamino-7-
(2-chloroanilino) fluoran, 3-dibutylamino-7- (o-chlorophenyl) aminofluoran, 3
-Diethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-phenylaminofluoran, 3-diethylamino-6-methyl-7
-Xylidinofluoran, 3-diethylamino-7-
(2-chloroanilino) fluoran, 3-diethylamino-7- (o-chlorophenyl) aminofluoran, 3
-Diethylamino-7- (o-chlorophenyl) amino-fluoran, 3-diethylamino-7- (2-carbomethoxy-phenylamino) fluoran, 3- (N-cyclohexyl-N-methyl) amino-6-methyl-7-
Anilinofluoran, 3- (N-cyclohexyl-N-
Methyl) amino-6-methyl-7-phenylaminofluoran, 3- (N-cyclopentyl-N-ethyl) amino-6-methyl-7-phenylaminofluoran, 3-
(N-isoamyl-N-ethyl) amino-6-methyl-
7-anilinofluoran, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluoran, 3-
(N-ethyl-p-toluidino) -6-methyl-7-
(P-toluidino) fluoran, 3- (N-ethyl-N
-Isoamyl) amino-6-methyl-7-phenylaminofluoran, 3- (N-methyl-N-tetrahydrofurfuryl) amino-6-methyl-7-phenylaminofluoran, 3- (N-ethyl-N -Tetrahydrofurfuryl) amino-6-methyl-7-phenylaminofluoran, 3-pyrrolidino-6-methyl-7-phenylaminofluoran, 3-pyrrolidino-6-methyl-7-p-
Butylphenylaminofluoran, 3-piperidino-6
-Methyl-7-phenylaminofluoran, 2-phenylamino-3-methyl-6- (N-ethyl-Np-toluyl) amino-fluoran and the like, but the present invention is not limited to these. Absent. In the present invention, the dye precursor provided with the color control layer on the surface may be a mixture of the dye precursors that form each color, and the respective color tones are not limited as long as the mixture forms a blackish color.

Next, the color control layer of the present invention is formed by using the above black color dye precursor as a dispersion medium in water or in water-compatible methyl alcohol, ethyl alcohol, isopropyl alcohol, acetone, methyl ethyl ketone, ethylene glycol or the like. After the dispersion with a mixed solution of the above, a vinyl monomer and a polymerization initiator are added, and the mixture is heated if necessary to produce the polymer. Here, the vinyl monomer used is a compound having at least one vinyl bond (carbon-carbon double bond) in its molecule, and the vinyl bond becomes an active site and is capable of addition polymerization.

Various states can be considered as a mixed state when the vinyl monomer is added to the dispersion of the dye precursor. That is, 1) Most of the dispersion of the dye precursor and the vinyl monomer are phase-separated to form separate phases or are in an emulsified state, but a very small amount of the vinyl monomer is a dispersion of the dye precursor. 2) A state in which the dispersion liquid of the dye precursor and the vinyl monomer are completely dissolved and completely phase-separated 3)
Examples include a state in which the vinyl monomer is completely dissolved in most or all of the dispersion, but among these states,
When polymerization is performed in a state in which a very small amount of the vinyl monomer of 1) is dissolved in the dispersion liquid of the dye precursor, the surface of the particles of the dye precursor is more polished than in the case where polymerization is performed in another state. This is a preferable state because a uniform and dense color-developing layer can be formed. Such a state can be realized by appropriately selecting the type of dispersion medium for dispersing the dye precursor particles and the type of vinyl monomer.

The vinyl monomer includes a compound having one vinyl bond and a compound having two or more vinyl bonds. By changing the content of the compound having two or more vinyl bonds, the characteristics of the color control layer can be freely changed. Compared to those polymerized with a compound having only one vinyl bond, the color-controlling layer using a compound having two or more vinyl bonds together has a stronger crosslinked structure, and the color-forming start temperature when a thermosensitive recording material is formed. Can be higher. The combination ratio of the compound having two or more vinyl bonds is preferably 1% by weight or more and 70% by weight or less, and more preferably 10% by weight or more and 50% by weight or less based on the total weight of the vinyl monomer. Within this range, it is possible to arbitrarily adjust the color development characteristics such as the color development start temperature, and it becomes easy to adjust the color separation in the multicolor heat-sensitive recording material.

The total amount of the vinyl monomer based on the dye precursor particles is preferably 0.5% by weight or more and 1000% by weight or less. In this case, the polymerization proceeds without agglomeration during the polymerization, and a coating having a sufficient function as a color control layer is obtained.

Specific examples of the compound having only one vinyl bond in the present invention include styrene, α-methylstyrene, α-methoxystyrene, m-bromostyrene and m-bromostyrene.
-Chlorostyrene, o-bromostyrene, o-chlorostyrene, p-bromostyrene, p-chlorostyrene, p
-Methylstyrene, p-methoxystyrene, 2-vinylpyridine, isobutene, 3-methyl-1-butene, butyl vinyl ether, methyl vinyl ketone, nitroethylene, vinylidene cyanide, ethylene, propylene, vinyl chloride, vinyl acetate, acrolein, Methyl acrolein, acrylamide, N-methylol acrylamide,
N, N-dimethylacrylamide, diacetoneacrylamide, N-octadecylacrylamide, ethyl α-acetoxyacrylate, ethyl α-chloroacrylate,
α-Methyl chloroacrylate, α-methyl methyl cyanoacrylate, α-methyl acrylate, benzyl acrylate, butyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, acrylic acid Tridecyl, acrylic acid-
2-hydroxyethyl, 2-hydroxypropyl acrylate, 2-methoxyethyl acrylate, 2-butoxyethyl acrylate, ethoxyethoxyethyl acrylate, methyl triglycol acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate , Cyanoethyl acrylate, ferrocenylmethyl acrylate, glycidyl acrylate, heptafluorobutyl acrylate, methyl acrylate, octyl acrylate, methyl trifluoroacrylate, 2-chloroethyl acrylate, 2-nitrobutyl acrylate, Acrylic acid, α
-Bromoacrylic acid, 2-hydroxyethylacryloyl phosphate, acrylonitrile, allyl glycidyl ether, allyl acetic acid, allyl alcohol, allyl benzene, N-allyl stearyl amide, 1-butene, 2-
Butene, N-vinylcaprolactam, ethyl N-vinylcarbamate, N-vinylcarbazole, crotonaldehyde, crotonic acid, 1,1-diphenylethylene, tetrafluoroethylene, diethyl fumarate, 1-hexene, 1-vinylimidazole, 1 -Vinyl-2-methylimidazole, indene, diethyl maleate, maleic anhydride, maleimide, methacrylamide, benzyl methacrylate, ethyl methacrylate, ferrocenylmethyl methacrylate, glycidyl methacrylate, isopropyl methacrylate, propyl methacrylate, Methacrylic acid-
n-butyl, isobutyl methacrylate, methacrylic acid-
sec-butyl, t-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, isodecyl methacrylate, lauryl methacrylate,
Tridecyl methacrylate, stearyl methacrylate, methyl methacrylate, phenyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-ethoxyethyl methacrylate, tetrahydrofurfuryl methacrylate, dimethylamino methacrylate Ethyl, diethylaminoethyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, methacrylic acid, methacryloxyethyl phosphate, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, N-methylol methacrylamide, methacrylonitrile, methacryloyl acetone , 2-isopropenyl-2-oxazoline, 2-vinylquinoline, vinyl benzoate, vinyl dodecyl ether, vinyl Ethyl sulfoxide, vinyl formate, vinyl isobutyl ether, vinyl laurate, although vinyl phenyl ether, the present invention is not limited thereto.

Specific examples of the compound having two or more vinyl bonds include polyethylene glycol diacrylates such as ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, and octaethylene glycol diacrylate. Acrylates, polyethylene glycol dimethacrylates such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and tetraethylene glycol dimethacrylate, 2,2-bis (4-acryloxyethoxyphenyl) propane, 2,2- Bis (4-acryloxydiethoxyphenyl) propane, 2,2-bis (4-acryloxytriethoxyphene) B) 2,2-bis (4-acryloxypolyethoxyphenyl) propanes such as propane, 2,2-bis (4-methacryloxyethoxyphenyl) propane, 2,2-bis (4-methacryloxydiethoxyphenyl) 2,2) such as propane and 2,2-bis (4-methacryloxytriethoxyphenyl) propane
-Bis (4-methacryloxypolyethoxyphenyl) propanes, allyl acrylate, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,5-pentanediol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, polypropylene glycol diacrylate, N, N'-methylenebisacrylamide, allyl methacrylate, 1,3-butanediol dimethacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, Dipropylene glycol dimethacrylate, diallyl phthalate, diallyl chlorendate, butadiene, ethyl butadiene-1-carboxylate, diethyl butadiene-1,4-dicarboxylate Diallyl melamine, diallyl phthalate, N, N-divinyl aniline, divinyl ether,
Divinylbenzene, divinylnaphthalene, 1,3-butanediol dimethacrylate, isoprene, pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylolethane trimethacrylate, trimethylolpropane trimethacrylate,
Examples include triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, tetramethylolmethanetetraacrylate, tetramethylolmethanetetramethacrylate, and the like, but the present invention is not limited thereto.

The above-mentioned vinyl compounds according to the present invention can be used alone or in combination of two or more. When used in combination of two or more, as described above,
A combination of a compound having one vinyl bond and a compound having two or more vinyl bonds is preferable, but a combination of compounds having one vinyl bond and compounds having two or more vinyl bonds can also be used.

When some or all of these vinyl monomers are methacrylates, the methacrylates and their polymers have good adhesion to the dye precursor particles provided with the color control layer, It has good solubility in the dispersion medium and good polymerizability, so it is possible to efficiently coat the surface of the dye precursor particles by addition polymerization, and furthermore, it has a function of adjusting color development characteristics such as color development start temperature. And are particularly preferably used in the present invention.

As the polymerization initiator to be added for the addition polymerization of the vinyl monomer, known ones can be used. The type of the polymerization reaction is not particularly limited, such as radical polymerization, anionic polymerization and cationic polymerization. Particularly preferably used. During the polymerization, the system may be heated as required. Specific examples of the polymerization initiator for radical polymerization are shown below. Hydrogen peroxide, cumene hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide, di-
Peroxides such as t-butyl peroxide, benzoyl peroxide and lauroyl peroxide, persulfates such as potassium persulfate and ammonium persulfate, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2 , 4-Dimethylvaleronitrile), 2,2'-azobis (4-methoxy-
Azo compounds such as 2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylpropionamidine) dihydrochloride, and 4,4'-azobis (4-cyanovaleric acid), hydrogen peroxide and ferrous iron Combination of salt, combination of persulfate and sodium acid sulfite, combination of cumene hydroxyperoxide and ferrous salt, combination of benzoyl peroxide and diethylaniline, combination of peroxide and metal alkyl, combination of oxygen and organic metal alkyl Redox initiators and the like. These may be used not only alone but also in a mixture.

The polymerization initiator for radical polymerization is not particularly limited as long as it generates active radicals by heat or light energy other than those described above. In this case, it is particularly preferable to use a water-soluble polymerization initiator such as potassium persulfate, ammonium persulfate, and 2,2'-azobis (2-methylpropionamidine) dihydrochloride.

The amount of the polymerization initiator to be added is not particularly limited as long as the vinyl monomer starts the addition polymerization. Is preferably not less than 0.001 and not more than 10% by weight.

Next, examples of the color developing agent which reacts with the above-described red color dye precursor dispersed particles or the black color dye precursor having a color control layer on the surface to form a color include the following. It is used as dispersed particles in the same manner as the coloring dye precursor.

4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4-
Hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxy-4'-benzyloxydiphenylsulfone, 4-hydroxy-4'-propoxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 3,4- Dihydroxy-4'-methyldiphenylsulfone, 4-hydroxy-4'-benzenesulfonyloxydiphenylsulfone, 2,4-bis (phenylsulfonyl) phenol, p-phenylphenol, p-hydroxyacetophenone, 1,1-bis (p
-Hydroxyphenyl) propane, 1,1-bis (p-
Hydroxyphenyl) pentane, 1,1-bis (p-hydroxyphenyl) hexane, 1,1-bis (p-hydroxyphenyl) cyclohexane, 2,2-bis (p-
(Hydroxyphenyl) propane, 2,2-bis (p-hydroxyphenyl) hexane, 1,1-bis (p-hydroxyphenyl) -2-ethylhexane, 2,2-bis (3-chloro-4-hydroxyphenyl) propane,
1,1-bis (p-hydroxyphenyl) -1-phenylethane, 1,3-di- [2- (p-hydroxyphenyl) -2-propyl] benzene, 1,3-di- [2-
(3,4-dihydroxyphenyl) -2-propyl] benzene, 1,4-di- [2- (p-hydroxyphenyl) -2-propyl] benzene, 4,4'-hydroxydiphenyl ether, 3,3'- Dichloro-4,4'-
Hydroxydiphenyl sulfide, 2,2-bis (4-
Methyl hydroxyphenyl) acetate, 2,2-bis (4-
(Hydroxyphenyl) butyl acetate, 4,4'-thiobis (2-tert-butyl-5-methylphenol), 4
Dimethyl-hydroxyphthalate, benzyl 4-hydroxybenzoate, methyl 4-hydroxybenzoate, benzyl gallate, stearyl gallate, N, N′-diphenylthiourea, 4,4′-bis (3- (4-methyl Phenylsulfonyl) ureido) diphenylmethane, N- (4-
Methylphenylsulfonyl) -N′-phenylurea, salicylanilide, 5-chlorosalicylanilide, salicylic acid, 3,5-di-tert-butylsalicylic acid,
3,5-di-α-methylbenzylsalicylic acid, 4-
[2 '-(4-methoxyphenoxy) ethyloxy] salicylic acid, 3- (octyloxycarbonylamino) salicylic acid or a metal salt of these salicylic acid derivatives, N
-(4-hydroxyphenyl) -p-toluenesulfonamide, N- (4-hydroxyphenyl) benzenesulfonamide, N- (4-hydroxyphenyl) -1-naphthalenesulfonamide, N- (4-hydroxyphenyl)- 2-naphthalenesulfonamide, N- (4-hydroxynaphthyl) -p-toluenesulfonamide, N-
(4-hydroxynaphthyl) benzenesulfonamide,
N- (4-hydroxynaphthyl) -1-naphthalenesulfonamide, N- (4-hydroxynaphthyl) -2-naphthalenesulfonamide, N- (3-hydroxyphenyl) -p-toluenesulfonamide, N- (3- Hydroxyphenyl) benzenesulfonamide, N- (3-hydroxyphenyl) -1-naphthalenesulfonamide,
N- (3-hydroxyphenyl) -2-naphthalenesulfonamide and the like can be mentioned. These are used singly or as a mixture of two or more, and are used in a proportion of 100 to 700, preferably 150 to 400 parts by weight based on 100 parts by weight of the total amount of the dye precursor.

Next, in the present invention, a blue-green colorant is added to the heat-sensitive recording layer in order to improve color bleeding around characters at the time of high-temperature coloring. Further, when high preservability of the recorded image is required, one or more protective layers are laminated on the heat-sensitive recording layer, and a coloring agent is added to at least one of the heat-sensitive recording layer and the protective layer. You.

Such colorants include a color dye and a color pigment described below, and are not limited to these as long as they are blue-green colorants. Methylene Blue, CI Disperse Blue 3, CI Sulfur Blue 7, CI Solvent Blue 22, CI Acid Blue 5
9, CI Mordant Blue 10, CI Bat Blue 4
1. Blue dyes such as CI Direct Blue 86. Green dyes such as methylene green, CI basic green 4, and CI mordant green 4. Ultramarine, navy blue, cobalt blue, cerulean blue, kasu, alkali blue lake,
Peacock Blue Lake, Victoria Pure Blue Lake, Victoria Blue Lake, Metal-Free Phthalocyanine Blue, Phthalocyanine Blue, Monochrome Copper Phthalocyanine, Fast Sky Blue, Indanthrene Blue R
Blue pigments such as S, Indanthrene Blue BC, Indigo and the like. Chrome green, zinc green, chromium oxide, viridian, emerald green, cobalt green, pigment green B, naphthol green B, green gold, acid green lake, malachite green lake, diamond green lake, phthalocyanine green, polychlorobrom copper phthalocyanine, poly Green pigments such as bromophthalocyanine.

Of these, phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green are particularly excellent in dispersibility, coloring properties, and weather resistance of the colored background when used as a heat-sensitive recording material, and are effectively used in the present invention. You.

These colorants are used alone or in combination of two or more in the form of a solution or dispersion in a solvent.
The addition amount is 0.001 to 1% by weight based on the total solid content of the heat-sensitive recording layer and the protective layer, and is added to the heat-sensitive recording layer and the protective layer to such an extent that the background is colored pale blue or pale green. . In accordance with the measurement method specified in JIS-Z8722, when represented by the color difference value specified in JIS-Z8730, L * value = 80 to 95, a * = − 10 to 2, b * = −
It is better to adjust so as to be 10 to 2.

Here, a water-soluble resin, a water-dispersible resin or the like is used for the protective layer formed on the heat-sensitive recording layer. For example, starches, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol,
Modified polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, polyacrylate, polymethacrylate, sodium polyacrylate, polyethylene terephthalate, polybutylene terephthalate, chlorinated polyether, allyl resin, furan resin, ketone resin, oxybenzoyl Polyester, polyacetal, polyetheretherketone, polyethersulfone, polyimide, polyamide, polyamideimide, polyaminobismaleimide, polymethylpentene, polyphenylene oxide, polyphenylene sulfide, polyphenylene sulfone, polysulfone, polyarylate, polyallyl sulfone, polybutadiene, polycarbonate, Polyethylene, polypropylene, polystyrene, polyvinyl chloride,
Polyvinylidene chloride, polyvinyl acetate, polyurethane,
Phenolic resin, urea resin, melamine resin, melamine formalin resin, benzoguanamine resin, bismaleimide triazine resin, alkyd resin, amino resin, epoxy resin, unsaturated polyester resin, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer,
Methyl acrylate / butadiene copolymer, ethylene / vinyl acetate copolymer, acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid terpolymer, styrene / maleic anhydride copolymer Examples thereof include an alkali salt of a polymer, an alkali salt or an ammonium salt of an ethylene / maleic anhydride copolymer, and various other polyolefin-based resins. These may be used alone or as a mixture of two or more kinds. The layers may be stacked as described above.

A coloring agent is added to the protective layer. In addition to the coloring agent, conventionally known additives such as an oil-absorbing pigment, an ultraviolet absorber, and a fluorescent dye may be added. Various printings represented by an ultraviolet curable ink can be performed on the uppermost layer of the protective layer as long as the color hue of the printed portion is not hindered.

The heat-sensitive recording layer according to the present invention is prepared by adding a binder, a sensitizer, an oil-absorbing pigment, a surfactant and the like, which are conventionally known in the field of heat-sensitive recording paper, in addition to the above main constituent materials. Coated on top.

Examples of the binder include starches, hydroxyethylcellulose, methylcellulose, ethylcellulose, carboxymethylcellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, polyacrylic acid ester, polymethacrylic acid ester, polymethacrylic acid ester. Sodium acrylate, polyethylene terephthalate, polybutylene terephthalate, chlorinated polyether, allyl resin, furan resin, ketone resin, oxybenzoyl polyester, polyacetal, polyetheretherketone, polyethersulfone, polyimide, polyamide, polyamideimide, polyaminobismaleimide , Polymethylpentene, polyphenylene oxide, polyphenylene sulfide, polyphenylene Sulfone, polysulfone, polyallylate, polyallyl sulfone, polybutadiene, polycarbonate, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyurethane, phenolic resin, urea resin, melamine resin, melamine formalin resin, benzoguanamine resin , Bismaleimide triazine resin, alkyd resin, amino resin, epoxy resin, unsaturated polyester resin, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, ethylene / vinyl acetate copolymer , Acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid terpolymer, styrene / maleic anhydride copolymer Alkali salt of,
An alkali salt or ammonium salt of an ethylene / maleic anhydride copolymer, and other various polyolefin resins are used.

As the sensitizer, those having a melting point of 60 ° C. to 180 ° C. are preferable, and those having a melting point of 80 ° C. to 140 ° C. are more preferably used. Specifically, stearamide, N-hydroxymethyl stearamide,
N-stearylstearic acid amide, ethylene bisstearic acid amide, N-stearylurea, benzyl-2-
Naphthyl ether, m-terphenyl, 4-benzylbiphenyl, 2,2'-bis (4-methoxyphenoxy)
Diethyl ether, α, α′-diphenoxyxylene,
Bis (4-methoxyphenyl) ether, diphenyl adipate, dibenzyl oxalate, di (4-chlorobenzyl) oxalate, dimethyl terephthalate, dibenzyl terephthalate, phenyl benzenesulfonate, bis (4-allyloxyphenyl) Sulfone, 4-
Known sensitizers such as acetylacetophenone, acetoacetic anilide, fatty acid anilide and the like can be mentioned. These compounds can be used alone or in combination of two or more. In order to obtain a sufficient thermal response, the sensitizer preferably accounts for 5 to 50% by weight of the total solid content of the heat-sensitive recording layer.

As the oil-absorbing pigment, inorganic and organic pigments such as diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, and urea-formalin resin are used. You.

In addition, higher fatty acid metal salts such as zinc stearate and calcium stearate, and waxes such as paraffin, paraffin oxide, polyethylene, polyethylene oxide, stearic acid amide, caster wax, etc.
In addition, a surfactant such as sodium dioctylsulfosuccinate, a fluorescent dye, and the like can be contained.

Further, an antioxidant and an ultraviolet absorber can be added for the purpose of improving light resistance. Examples of antioxidants include, but are not particularly limited to, hindered amine antioxidants, hindered phenol antioxidants, and sulfide antioxidants. Examples of the UV absorber include organic UV absorbers such as benzotriazole UV absorber, salicylic acid UV absorber, and benzophenone UV absorber; and inorganic UV absorbers such as zinc oxide, titanium oxide, and cerium oxide. Although an absorbent is mentioned, it is not particularly limited.

Next, the support on which the heat-sensitive recording layer according to the present invention is provided is made of various papers, nonwoven fabrics, woven fabrics, synthetic resin films,
Synthetic resin laminated paper, synthetic paper, metal foil, etc. can be used, and especially, heat-sensitive coated paper pre-coated with an oil-absorbing pigment to enhance the sensitivity of the heat-sensitive recording material or to prevent print residue is effective as a support. is there.

In the case where a dense, thick layer is previously formed on the back surface of the paper as a support, in particular, a magnetic recording material layer is applied to the support, the high sensitivity multicolor recording layer is applied to the front surface. Because the moisture at the time of drying does not escape to the back side, the background fog of the low-temperature color is large, and in the present invention, the background is colored to a pale blue color or a pale green color, and the color separation of red and black is improved for the first time. We were able to.

[0042]

The present invention will be described in more detail with reference to the following examples. The following parts are parts by weight, and% is% by weight.
And L * value, a * value and b * value are JIS-Z87
According to JIS-Z8730
Represents the color difference value specified by.

(A) Preparation of Coating Solution for Forming Multicolor Thermosensitive Recording Layer 5 parts of 3-dibutylamino-6-methyl-7-anilinofluoran, a black coloring dye precursor, was dissolved in a 2.5% aqueous solution of polyvinyl alcohol. With a ball mill together with 85 parts, a dye precursor dispersion having a volume average particle size of 1 μm was obtained. Next, this dispersion was transferred to a polymerization vessel, and 4 parts of methyl methacrylate and 1 part of ethylene glycol dimethacrylate were added, and the temperature was raised to 70 ° C. with stirring. To this, 5 parts of a 1% aqueous solution of potassium persulfate as a polymerization initiator was added, and the mixture was reacted for 6 hours while stirring was continued. It is then cooled to room temperature,
As a result, 100 parts of a dispersion of black color dye precursor particles having a color control layer on the surface was obtained. Further, 3-, which is a red coloring dye precursor,
Diethylamino-6-methyl-7-chlorofluoran 2
The mixture was pulverized with a ball mill together with 8 parts of a 2% aqueous solution of polyvinyl alcohol to obtain 10 parts of a red coloring dye precursor dispersion having a volume average particle diameter of 1 μm. Then, 3,3'-
6 parts of diallyl-4,4'-dihydroxydiphenylsulfone was pulverized in a ball mill together with 14 parts of a 2% aqueous solution of polyvinyl alcohol to obtain 20 parts of a developer dispersion having a volume average particle diameter of 1 μm. Further, 6 parts of 2-benzyloxynaphthalene as a sensitizer was added to a 2% aqueous solution of polyvinyl alcohol 14
Part and pulverized with a ball mill to obtain 2 μm
20 parts of a benzyloxynaphthalene dispersion were obtained. Further, 5 parts of calcium carbonate (Univar 70, manufactured by Shiraishi Kogyo Co., Ltd.) was dispersed with a homogenizer together with 10 parts of a 2% aqueous sodium hexametaphosphate solution to obtain 15 parts of a calcium carbonate dispersion having a volume average particle diameter of 1 μm. The above five dispersions and 0.5 part of a 1% aqueous solution of methylene blue were mixed to prepare a coating liquid for forming a multicolor heat-sensitive recording layer.

(B) Preparation of heat-sensitive coated paper A coating liquid composed of 100 parts of calcined kaolin, 24 parts of a 50% styrene-butadiene-based latex aqueous dispersion and 200 parts of water was mixed with a high-quality paper having a basis weight of 50 g / m ² . The coating was dried to give a solid content of 9 g / m ² and dried to prepare a heat-sensitive coated paper.

Example 1 The coating solution for forming a multicolor heat-sensitive recording layer prepared in (A) was
On the heat-sensitive coated paper prepared in (B), the solid coating amount is 7
g / m < ² > and dried, and then calendered so that the coated surface has a Bekk smoothness of 400 to 500 seconds to produce a multicolor heat-sensitive recording material. The background portion is represented by an L * value / a * value / a * value measured by SpectroEye manufactured by Macbeth.
b * values are 93.57 / -0.15 / -3.5, respectively.
6 and pale blue.

(C) Preparation of Magnetic Paper for Thermal Coating Barium Ferrite (MC127 manufactured by Toda Kogyo) 100
Part, 30 parts of urethane-acrylic resin, 5 parts of polyethylene oxide (manufactured by Sumitomo Seika) and 2 parts of zinc stearate having an average particle diameter of 0.9 μm dispersed in polyvinyl alcohol.
Forty parts of a 5% aqueous dispersion was mixed with 200 parts of water and pulverized with a ball mill to prepare a coating solution for the magnetic recording layer. Next, the grammage of 160
g / m ² of high-quality paper, the above-mentioned magnetic recording layer coating solution is applied so as to have a solid content of 30 g / m ² and dried after magnetic field orientation.
50% styrene butadiene latex aqueous dispersion 24
Parts of water and 200 parts of water were applied to a solid content of 9 g / m ² as a coating amount and dried to prepare a heat-sensitive coating magnetic paper.

Example 2 A multicolor heat-sensitive recording material was produced in the same manner as in Example 1, except that the heat-sensitive coated paper (B) in Example 1 was changed to a magnetic paper (C) for heat-sensitive coating. The background is Macbeth Spec
The L * value / a * value / b * value measured by troEye was 90.25 / -1.52 // 4.21, respectively, which was light blue.

Example 3 A multicolor heat-sensitive recording material was prepared in the same manner as in Example 1 except that 0.5 part of a 1% aqueous solution of methylene blue in Example 1 was changed to 0.5 part of a 1% dispersion of phthalocyanine blue. Was prepared. In the background, the L * value / a * value / b * value measured by SpectroEye manufactured by Macbeth was 90.52 /
It was -1.24 / -4.52, which was light blue.

Example 4 0.5 part of a 1% aqueous solution of methylene blue of Example 1 was added to 0.5 part of a 1% dispersion of phthalocyanine green, and the heat-sensitive coating paper (B) was coated with magnetic paper for heat-sensitive coating. A multicolor heat-sensitive recording material was produced in the same manner as in Example 1 except that the material was changed to (C). The background is SpectroEy made by Macbeth
The L * value / a * value / b * value measured at e
9.25 / -4.53 / -2.56, which was light green.

(D) Coating solution for forming protective layer 30 parts of a 20% aqueous dispersion of aluminum hydroxide, 5 parts of a 40% aqueous dispersion of zinc stearate, 200 parts of a 10% aqueous solution of polyvinyl alcohol, and 1 part of phthalocyanine blue %
2 parts of the dispersion was mixed with 115 parts of water to prepare a coating liquid for forming a protective layer.

Example 5 0.5 part of a 1% aqueous solution of methylene blue of Example 1 was
Part, except that the multicolor heat-sensitive recording layer was coated in the same manner as in Example 1, and the coating liquid for forming a protective layer adjusted in (D) was coated on the multicolor heat-sensitive recording layer. After coating and drying to ² g / m ² , the coating surface has a Beck smoothness of 700 to 700 g / m ^2.
A calendar treatment was performed for 800 seconds to produce a multicolor heat-sensitive recording material. The background is Spectro made by Macbeth
The L * value / a * value / b * value measured by Eye
90.57 / −2.35 / −4.56, which was a pale blue color.

Example 6 2 parts of 3-diethylamino-6-methyl-7-chlorofluorane of Example 1 were added to 2 parts of 3-diethylamino-7-chlorofluorane, and 0.5% of a 1% aqueous solution of methylene blue was added. Part of a 1% dispersion of phthalocyanine blue.
A multicolor heat-sensitive recording material was produced in the same manner as in Example 1 except that the amount was changed to 5 parts. The background is Macbeth's Spect
The L * value / a * value / b * value measured by roEye was 90.57 / -3.59 / -5.62, respectively, indicating a light blue color.

Example 7 2 parts of 3-diethylamino-6-methyl-7-chlorofluorane of Example 1 was added to 2 parts of 3-diethylamino-7-chlorofluoran in 0.5% of a 1% aqueous solution of methylene blue.
To 0.5 part of a 1% dispersion of phthalocyanine green,
And heat-sensitive coated paper (B) is converted to magnetic paper for heat-sensitive coating (C)
A multicolor heat-sensitive recording material was produced in the same manner as in Example 1 except that the composition was changed to. The background is Spectro made by Macbeth
The L * value / a * value / b * value measured by Eye
87.57 / -5.65 / -4.56, which was light green.

(E) Preparation of Coating Solution for Forming Multicolor Thermosensitive Recording Layer 5 parts of 3-dibutylamino-6-methyl-7-anilinofluoran, a black coloring dye precursor, was dissolved in a 2.5% aqueous solution of polyvinyl alcohol. 15 parts together with a ball mill were pulverized to obtain 20 parts of a dispersion of a black coloring dye precursor. In addition, 2 parts of 3-diethylamino-7-chlorofluorane, which is a red-coloring dye precursor, is pulverized with a ball mill together with 8 parts of a 2% aqueous solution of polyvinyl alcohol, and 10 parts of a red-coloring dye precursor dispersion having a volume average particle diameter of 1 μm is prepared. Obtained. Then, the developer 3,
6 parts of 3'-diallyl-4,4'-dihydroxydiphenylsulfone were ground with a ball mill together with 14 parts of a 2% aqueous solution of polyvinyl alcohol to obtain 20 parts of a developer dispersion having a volume average particle diameter of 1 μm. Further, 6 parts of 2-benzyloxynaphthalene as a sensitizer were pulverized with a ball mill together with 14 parts of a 2% aqueous solution of polyvinyl alcohol to give a volume average particle diameter of 1 μm.
Thus, 20 parts of 2-benzyloxynaphthalene dispersion liquid of m were obtained. In addition, calcium carbonate (Univar 7 manufactured by Shiraishi Kogyo)
0) 5 parts of 2% sodium hexametaphosphate aqueous solution 10
With a homogenizer, and a volume average particle size of 1 μm
To obtain 15 parts of a calcium carbonate dispersion. The above five dispersions and 0.5 part of a 1% phthalocyanine blue dispersion were mixed to prepare a coating liquid for forming a multicolor heat-sensitive recording layer.

Comparative Example 1 The coating liquid for forming a multicolor heat-sensitive recording layer prepared in (E) was
On the heat-sensitive coated paper prepared in (B), the solid coating amount is 7
g / m < ² > and dried, and then calendered so that the coated surface has a Bekk smoothness of 400 to 500 seconds to produce a multicolor heat-sensitive recording material. The background portion is represented by an L * value / a * value / a * value measured by SpectroEye manufactured by Macbeth.
The b * values were 77.75 / 7.45 / 4.56, respectively, indicating a pale reddish rat.

Comparative Example 2 0.5 part of a 1% dispersion of phthalocyanine blue of Comparative Example 1 was added to 0.5 part of a 1% dispersion of phthalocyanine green.
A multicolor heat-sensitive recording material was produced in the same manner as in Comparative Example 1 except that the heat-sensitive coated paper (B) was changed to a magnetic paper for heat-sensitive coating (C). The background is Macbeth Spec
The L * value / a * value / b * value measured by troEye were 74.5 / 5.24 / 6.35, respectively, indicating a light gray color.

COMPARATIVE EXAMPLE 3 A multicolor heat-sensitive recording layer was coated in the same manner as in Comparative Example 1, and the protective layer-forming coating liquid adjusted in (D) was applied on the multicolor heat-sensitive recording layer at a solid content of 2 g. / M ² after coating and drying
The coated surface was calendered so that the Bekk smoothness was 700 to 800 seconds to prepare a multicolor heat-sensitive recording material. The background is L * measured by SpectroEye manufactured by Macbeth.
Value / a * value / b * value is 82.52 / 5.65, respectively.
/4.17, which is a pale reddish rat.

(F) Preparation of a Coating Solution for Forming a Multicolor Thermal Recording Layer A 6-part of 3-diethylamino-6-methyl-7- (3-trifluoromethylanilino) fluoran, which is a black color dye precursor, is converted into a chloride. Dissolved in 30 parts of methylene, and then added to this solution an adduct of trimethylolpropane and xylylene diisocyanate at a molar ratio of 1: 3 (Takenate D-110N manufactured by Takeda Chemicals, diluting solvent: ethyl acetate, concentration: 75%).
12 parts were added and mixed uniformly. 5% of this mixture
The mixture was added to 250 parts of an aqueous polyvinyl alcohol solution, dispersed at 25 ° C. using a homomixer, heated to 45 ° C., and continuously stirred for 5 hours to evaporate methylene chloride and ethyl acetate. Thereafter, the temperature was raised to 80 ° C., and a curing reaction was performed for 3 hours to obtain a dispersion of composite particles comprising a polymer substance selected from polyurea and polyurethane having a volume average particle diameter of 1.8 μm and a black coloring dye precursor. Obtained. In addition, 2 parts of 3-diethylamino-7-chlorofluorane, which is a red-coloring dye precursor, is pulverized with a ball mill together with 8 parts of a 2% aqueous solution of polyvinyl alcohol, and 10 parts of a red-coloring dye precursor dispersion having a volume average particle diameter of 1 μm is prepared. Obtained. Subsequently, 6 parts of 3,3'-diallyl-4,4'-dihydroxydiphenylsulfone as a color developer was added to a 2% aqueous solution of polyvinyl alcohol 14
Were milled with a ball mill to obtain 20 parts of a developer dispersion having a volume average particle size of 1 μm. In addition, 6 parts of 2-benzyloxynaphthalene as a sensitizer were pulverized by a ball mill together with 14 parts of a 2% aqueous solution of polyvinyl alcohol to obtain 20 parts of a 2-benzyloxynaphthalene dispersion having a volume average particle diameter of 1 μm. Further, 5 parts of calcium carbonate (Univar 70 manufactured by Shiroishi Kogyo) was added to a 2% aqueous sodium hexametaphosphate solution 1
Disperse with a homogenizer together with 0 parts, volume average particle size 1μ
m of calcium carbonate dispersion was obtained. The above five dispersions and 0.5 part of a 1% phthalocyanine blue dispersion were mixed to prepare a coating liquid for forming a multicolor heat-sensitive recording layer.

Comparative Example 4 The coating solution for forming a multicolor heat-sensitive recording layer prepared in (F) was
On the heat-sensitive coated paper prepared in (B), the solid coating amount is 7
g / m < ² > and dried, and then calendered so that the coated surface has a Bekk smoothness of 400 to 500 seconds to produce a multicolor heat-sensitive recording material. The background portion is represented by an L * value / a * value / a * value measured by SpectroEye manufactured by Macbeth.
b * value is 94.58 / 1.02 // 4.35, respectively.
It was pale blue.

(G) Preparation of Coating Solution for Forming Multicolor Thermosensitive Recording Layer (High-Temperature Coloring Layer) 3 parts of 3-dibutylamino-6-methyl-7-anilinofluoran, a black coloring dye precursor, was added in an amount of 2%. The mixture was ground with a ball mill together with 7 parts of an aqueous polyvinyl alcohol solution to obtain 10 parts of a dye precursor dispersion having a volume average particle size of 1 μm. Then
5 parts of 2,2'-bis {4- (4-hydroxyphenylsulfonyl) phenoxy} diethyl ether, which is a color developer, is pulverized with a ball mill together with 10 parts of a 2% aqueous solution of polyvinyl alcohol to obtain a color developer having a volume average particle diameter of 1 μm. Dispersion 15
Got a part. The two dispersions were mixed to prepare a coating liquid for forming a multicolor heat-sensitive recording layer (high-temperature coloring layer).

(H) Preparation of Coating Solution for Forming Multicolor Thermosensitive Recording Layer (Low-Temperature Color-Forming Layer) Three parts of 3-diethylamino-7-chlorofluorane, a red-coloring dye precursor, was added to a 2% aqueous solution of polyvinyl alcohol 7
And 10 parts of a dye precursor dispersion having a volume average particle diameter of 1 μm. Then, 5 parts of 3,3'-diallyl-4,4'-dihydroxydiphenylsulfone as a color developer was added to a 2% aqueous solution of polyvinyl alcohol 10
The resulting mixture was pulverized with a ball mill to obtain 15 parts of a developer dispersion having a volume average particle size of 1 μm. Further, 5 parts of 2-benzyloxynaphthalene as a sensitizer were pulverized with a ball mill together with 10 parts of a 2% aqueous solution of polyvinyl alcohol to obtain 15 parts of a 2-benzyloxynaphthalene dispersion having a volume average particle diameter of 1 μm. Further, 3 parts of calcium carbonate (Univar 70 manufactured by Shiroishi Kogyo) was added to a 2% aqueous sodium hexametaphosphate solution 7
With a homogenizer, and a volume average particle size of 1 μm
To obtain 10 parts of a calcium carbonate dispersion. The above four dispersions and 0.5 part of a 1% phthalocyanine blue dispersion were mixed to prepare a coating liquid for forming a multicolor heat-sensitive recording layer (low-temperature coloring layer).

Comparative Example 5 The coating liquid for forming a multicolor heat-sensitive recording layer (high-temperature color-forming layer) prepared in (G) was applied onto the heat-sensitive coating paper prepared in (B) at a solid content of 4 g / g. m ² , dried, and further coated thereon with a multicolor heat-sensitive recording layer (low-temperature coloring layer) -forming coating liquid prepared in (H) at a solid content of 3 g / m ^2. After coating and drying, the coating surface has a Beck smoothness of 4
A calender treatment was performed so that the recording time was from 00 to 500 seconds, to produce a multicolor heat-sensitive recording material. The background is Macbeth Spec
The L * value / a * value / b * value measured by troEye was 85.58 / −2.02 // 3.25, respectively, indicating a light blue color.

Comparative Example 6 2 parts of 3-diethylamino-6-methyl-7-chlorofluorane of Example 1 was added to 2 parts of 3-diethylamino-7-chlorofluorane, and 0.5% of a 1% aqueous solution of methylene blue was added. A multicolor heat-sensitive recording material was produced in the same manner as in Example 1, except that the parts were changed to 0 parts. The background portion is represented by an L * value / a * value / a * value measured by SpectroEye manufactured by Macbeth.
The b * values were 92.56 / 5.81 / 2.21 respectively, and the color was pale red.

Test 1 Printing Test and Evaluation of Multicolor Thermosensitive Recording Material The TDK print head (LH440) was applied to the multicolor thermosensitive recording materials of Examples 1 to 7 and the multicolor thermosensitive recording materials of Comparative Examples 1 to 6.
9) Okura Electric Thermal Facsimile Printing Tester (TH
-PMD), low-energy printing (red printing) of the letter "H" was performed at an applied voltage of 20 volts and an applied pulse of 1.0 millisecond, and the color tone was visually observed. In addition, high energy printing (black printing) and solid black printing of the character "H" were performed with an applied pulse of 2.0 milliseconds. Black "H"
, The degree of color bleeding is determined from the color tone of the black printing portion, and the density of the solid black printing portion is determined by a Macbeth densitometer (RD91).
Measured in 8) and used as a measure of high-temperature color sensitivity. The results are shown in Table 1.

Test 2 Printing test and evaluation of the multicolor heat-sensitive recording material after light exposure The multicolor heat-sensitive recording materials of Examples 1 and 3 and the multicolor heat-sensitive recording material of Comparative Example 1 were exposed to direct sunlight for two days. Later, T
Using an Okura Denki thermal facsimile printing tester (TH-PMD) with a DK print head (LH4409), "H" at an applied voltage of 20 volts and an applied pulse of 1.0 millisecond.
Was performed with low energy printing (red printing). In addition, high energy printing (black printing) of the character "H" was performed with an applied pulse of 2.0 milliseconds. The color tone of each printed character was visually observed. The results are shown in parentheses in Table 1.

[0066]

[Table 1]

In Table 1, MB is an abbreviation for methylene blue, PB is phthalocyanine blue, and PG is phthalocyanine green. In the red print color tone item, ◎ indicates that the color is very bright red, ○ indicates the color is colored red without black, and Δ indicates the color is brownish red with black. X indicates that the color is almost black or brown, which cannot be recognized as red.

In Table 1, the circle of the item of black print color tone is
The letter “H” indicates a state in which the letter “H” is black, the symbol “△” indicates a state in which the letter “H” is slightly brownish but looks black, and the symbol “x” indicates a state in which the letter “H” appears brown or maroon.

Further, in the color separation items in Table 1, ◎ indicates a state where the color separation between red and black is very clear, 状態 indicates a state where the color separation between red and black is clear, and Δ indicates a state where the color separation is clear. The color separation of black is slightly indistinct, and x indicates that the color separation of red and black is indistinct.

Table 1 and L * values of Examples and Comparative Examples, a
As is clear from the * and b * values, Examples 1 to 7 of the present invention, which have both a colorant and a color-developing layer, have a vivid red printing color tone and a black printing color tone, that is, good color bleeding. Therefore,
Visually, it showed vivid resolution and color separation. On the other hand, in the comparative example, when the color-developing layer was not provided even when the coloring agent was used (Comparative Examples 1 to 3), the low-temperature red color tone was poor. The separation is very bad. When the black dye precursor was replaced with a composite particle system instead of the color control layer (Comparative Example 4), 2 parts of the red-black dye precursor were used.
When the layers were separated into layers (Comparative Example 5), the color bleeding was poor, and the color-developing control layer of the present invention was combined with a coloring agent.
It is understood that the color separation effect is exhibited for the first time. Furthermore, according to the present invention, when the support is magnetic recording paper (Example 2,
The background (L * value) of (4, 7) is worse than that of non-magnetic recording paper (Examples 1, 3, and 6), but is not as bad as that of the case without the color control layer (Comparative Example 2). It can be seen that the effect of the present invention is great even when the support is magnetic recording paper. In addition, even when the colorant was added to the protective layer (Example 5), the difference in color separation was remarkable as compared with the case where the color control layer was not used (Comparative Example 3). Further, it can be seen from Examples 1, 3 and Comparative Example 1 that phthalocyanine blue is better than methylene blue in image preservability after light exposure. When 3-diethylamino-7-chlorofluorane (Example 6) is used as a red dye precursor, 3-dibutylamino-6-
Compared with methyl-7-anilinofluoran (Example 3), the color tone of red printing was remarkably improved, and it was found to be an excellent red dye precursor in the present invention.

[0071]

As described above, according to the present invention, the color separation between a low-temperature color (red color) and a high-temperature color (black color) is good.
A multicolor heat-sensitive recording material having high resolution due to color bleeding and good image storability could be provided.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) B41M 5/18 105

Claims (5)

[Claims] 1. A thermosensitive recording comprising, on a support, two or more kinds of electron-donating dye precursors which develop colors different from each other, and one or more kinds of color developing agents which form the dye precursors upon heating. In a multicolor heat-sensitive recording material provided with a layer, the dye precursor is obtained by addition-polymerizing 1) one or more kinds of dye precursor dispersed particles emitting a reddish color and 2) a vinyl monomer. The thermosensitive recording layer is formed of one or more dye precursors having a color control layer on the surface and developing a black color, and the heat-sensitive recording layer is colored to a pale blue color or a pale green color by a colorant. Multicolor heat-sensitive recording material. 2. A thermosensitive recording comprising, on a support, at least two types of electron-donating dye precursors that develop colors different from each other, and at least one type of developer that causes the dye precursors to develop color when heated. A multicolor heat-sensitive recording material comprising a layer and one or more protective layers, wherein the dye precursor comprises: 1) one or more dye precursor-dispersed particles emitting a reddish color; And at least one of the heat-sensitive recording layer and the protective layer is made of a colorant. A multicolor heat-sensitive recording material characterized by being colored pale blue or pale green. 3. The multicolor heat-sensitive recording material according to claim 1, wherein said colorant is a phthalocyanine organic pigment. 4. The dye precursor which develops a reddish color is 3-diethylamino-7-chlorofluorane.
2. The multicolor heat-sensitive recording material as described in the item 2 or 3. 5. The multicolor thermosensitive recording material according to claim 1, wherein a magnetic recording layer is provided on the back surface of the support of the multicolor thermosensitive recording material.