JPH05116448A - Multi-color thermal recording body - Google Patents

Abstract

PURPOSE:To obtain a multi-color thermal recording body having good recording sensitivity and forming an image of a clear color tone with little color mixing and bleeding in a multi-color thermal recording body provided with two or more thermally color-forming layers forming different color tones on a substrate. CONSTITUTION:One of thermally color-forming layers of a multi-color thermal recording body contains 3,3-bis (p-dimethyl aminophenyl)-6- dimethyl aminophthalide, a color developer, and tetrakis (1,2,2,6,6-pentamethyl-4- piperidyl)-1,2,3,4-butane tetracarboxylate serving as a decoloring 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 having a plurality of color-developing layers which respectively develop different color tones.

[0002]

2. Description of the Related Art Conventionally, a heat-sensitive recording which utilizes a color reaction between a color-forming agent and a color-forming agent which develops color by contacting with the color-forming agent, by contacting both color-forming substances with heat to obtain a color-developed image. The body is well known. Since such a thermal recording medium is relatively inexpensive and the recording device is compact and its maintenance is relatively easy, it is used not only as a recording medium for facsimiles and various computers but also in a wide range of fields.

However, the performances and qualities required have been diversified with the expansion of applications, and for example, high sensitivity, image stabilization, multicolor recording, etc. have been mentioned. In particular, because of its wide range of application for multicolor recording, many recording materials have been researched and proposed so far.

The conventional multicolor recording materials are roughly classified into the following 2
It is divided into two. The first is a method in which the low temperature thermosensitive coloring layer is colored during low temperature heating, and both the low temperature thermosensitive coloring layer and the high temperature thermosensitive coloring layer are colored during high temperature heating to obtain a mixed color. The other is the method of the first method, in which a color-developing color tone of only the high-temperature heat-sensitive color-developing layer is obtained at the time of high-temperature heating by using a decolorizing agent having a decoloring effect on the color-developing system of low-temperature coloring at the time of high-temperature heating. ..

In the first method, the image becomes unclear due to color mixture and blurring occurs, so that the second method is generally suitable as a method for obtaining a multicolor image. Then, in the second method, various decolorizing agents having a decoloring effect on a color forming system composed of a basic leuco dye and an organic acidic substance have been proposed. However, when these decoloring agents are simply used in the vicinity of the high-temperature color-developing layer, there are disadvantages that a sufficient color-developing density cannot be obtained at the time of heating at a high temperature or the original color tone of the dye is changed.

In the second method, the decolorizing agent is generally provided in an adjacent layer capable of decoloring with respect to the thermosensitive coloring layer to be decolored, but the decolorizing effect is not sufficient. Not only that, but also the manufacturing process becomes complicated, which is not preferable.
On the other hand, it is not preferable to use a decolorizer in the heat-sensitive color developing layer to be decolored, because color development is generally hindered.

[0007]

DISCLOSURE OF THE INVENTION The present invention has improved the above-mentioned problems associated with the use of a decolorizing agent, and is capable of forming a clear color tone image having good recording sensitivity and less color mixture or blurring. A thermal recording material is provided.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, when a specific basic dye and a specific decoloring agent were combined in a low temperature color forming layer,
It has been found that a multicolor thermosensitive recording medium can be obtained which, even if contained in the same layer, does not interfere with color development at low temperature heating and can sufficiently perform decoloring action at high temperature heating.

That is, according to the present invention, in a multicolor thermosensitive recording medium having two or more thermosensitive coloring layers each of which develops a different color tone on a support, one of the thermosensitive coloring layers is a basic dye. , 3-Bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, a coloring agent that shows a color reaction with the basic dye, and tetrakis (1,2,2,6,6) which is a decoloring agent. -Pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate is contained in the multicolor heat-sensitive recording material.

[0010]

In the multicolor thermosensitive recording material of the present invention, at least one of the color-developing layers is 3,3-bis (p-dimethylaminophenyl).
-6-Dimethylaminophthalide (basic dye) and tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate (decolorizer) It is used together. The amount of the decoloring agent used is 50 to 1500 with respect to 100 parts by weight of the basic dye.
It is desirable to use it in an amount of 100 parts by weight, preferably 100 to 700 parts by weight. In addition, this decolorizer is water, an organic solvent,
It may be used by dispersing it in oil or the like, or may be encapsulated in a capsule. Further, it is possible to use a conventionally known decoloring agent in combination to the extent that the effects of the present invention are not impaired.

Various known compounds can be used as the color-forming agent which constitutes a color-forming system in combination with the 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, and the following are exemplified. It 4-tert-butylphenol, α-naphthol, β-naphthol, 4-acetylphenol, 4-tert-octylphenol,
4,4'-sec-butylidene diphenol, 4-phenylphenol, 4,4'-dihydroxy-diphenylmethane, 4,4'-isopropylidenediphenol, 1,
1-bis (4-hydroxyphenyl) -1-phenylethane, 1,4-bis (p-hydroxycumyl) benzene, hydroquinone, 4,4'-cyclohexylidene diphenol, 4,4 '-(1,3 -Dimethylbutylidene) bisphenol, 4,4'-dihydroxydiphenyl sulfide, 4,4'-thiobis (6-tert-butyl-3-methylphenol), 2,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxy Diphenyl sulfone, 4-hydroxy-4'-methyldiphenyl sulfone, 4-hydroxy-4'-methoxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, 4-hydroxy-3 ', 4'-trimethylene diphenyl Sulfone, 4-hydroxy-3 ',
4'-tetramethylene diphenyl sulfone, 3,4-dihydroxy-4'-methyldiphenyl sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone,
1,3-di [2- (4-hydroxyphenyl) -2-propyl] benzene, 1- [α-methyl-α- (4'-hydroxyphenyl) ethyl] -4- [α ', α'-bis (4 ″ -hydroxyphenyl) ethyl] benzene, di (p-hydroxyphenylthioethoxy) methane, di (p-hydroxyphenylthioethyl) ether, hydroquinone monobenzyl ether, bis (4-hydroxyphenyl) acetic acid butyl ester, 4-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,
4,4'-trihydroxybenzophenone, 2,2 ',
4,4'-Tetrahydroxybenzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, ethyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate, -sec-butyl 4-hydroxybenzoate, 4-hydroxy. Pentyl benzoate, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate,
Tolyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, phenylpropyl 4-hydroxybenzoate, phenethyl 4-hydroxybenzoate, p-chlorobenzyl 4-hydroxybenzoate, p-methoxybenzyl 4-hydroxybenzoate. , Novolac type phenolic resin, phenolic compounds such as phenolic polymer,
Benzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, terephthalaldehyde acid, 3-se
c-Butyl-4-hydroxybenzoic acid, 3-cyclohexyl-4-hydroxybenzoic acid, 3,5-dimethyl-4
-Hydroxybenzoic acid, salicylic acid, 3-isopropylsalicylic acid, 3-tert-butylsalicylic acid, 3,5-di-tert-butylsalicylic acid, 3-benzylsalicylic acid,
3- (α-methylbenzyl) salicylic acid, 3-chloro-
5- (α-methylbenzyl) salicylic acid, 3-phenyl-5- (α, α-dimethylbenzyl) salicylic acid, 3,
Aromatic carboxylic acids such as 5-di-α-methylbenzyl salicylic acid, and these phenolic compounds, aromatic carboxylic acids and polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin and nickel. Organic acidic substances such as salt. In addition, two or more kinds of the above-mentioned color formers can of course be used together if necessary.

In particular, 4,4'-cyclohexylidene diphenol, 4,4 '-(1,3-dimethylbutylidene) bisphenol, 4-hydroxy-4'-isopropoxydiphenyl sulfone, 2,4'-dihydroxydiphenyl When sulfone, 1,3-di [2- (4-hydroxyphenyl) -2-propyl] benzene, and more preferably 4,4'-cyclohexylidenediphenol, is used, the color density is high and the temperature is high. It is desirable that the color can be erased quickly.

The ratio of the basic dye to the color developing agent to be used should be appropriately selected according to the type of the color developing agent to be used and is not particularly limited, but generally 50 to 100 parts by weight of the basic dye. 700 parts by weight, preferably 100-400
About a part by weight of the coloring agent is used.

In the present invention, the color-forming layer may further contain an appropriate heat-fusible substance for the purpose of adjusting the color-forming temperature. As the heat-fusible substance, various known compounds can be used, for example, stearic acid amide, stearic acid methylenebisamide, stearic acid ethylenebisamide,
Oleic acid amides, palmitic acid amides, fatty acid amides such as coconut fatty acid amides, 4,4′-butylidene bis (6
-Tert-butyl-3-methylphenol), 1,1,3
-Hindered phenols such as tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane and 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, p -Benzylbiphenyl, p- (4-trioxy) biphenyl, 1,5-bis (4-methoxyphenoxy) -3-oxa-pentane, 1,2-bis (phenoxy) ethane, 1,2-bis (4-methyl) Phenoxy) ethane, 1,2-bis (3-
Ethers such as methylphenoxy) ethane, 1- (2-methylphenoxy) -2- (4-methoxyphenoxy) ethane, 2-naphtholbenzyl ether, dibenzyl terephthalate, 2-hydroxy-2-naphthoic acid-phenyl ester, Oxalic acid dibenzyl ester, oxalic acid di (4-methylbenzyl) ester, oxalic acid di (4
-Chlorobenzyl) ester and the like, 2-hydroxy-4-benzyloxybenzophenone, 2,4-
Di-tert-butylphenyl-3 ', 5'-di-tert-butyl-4'-hydroxybenzoate, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy -3 ', 5'-di-tert-
Butylphenyl) -5-chloro-benzotriazole,
2- (2'-hydroxy-3'-tert-butyl-5'-
Methylphenyl) -5-chloro-benzotriazole,
2- (2'-hydroxy-3 ', 5'-di-tert-aminophenyl) benzotriazole, 2- (2'-hydroxy-3', 5'-di-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-5'-tert-
Butylphenyl) benzotriazole, 2- (2'-hydroxy-5'-tert-octylphenyl) benzotriazole, 2- [2'-hydroxy-3 '-(3 ",
4 ", 5", 6 "-tetra-hydrophthalimidomethyl) -5'-methylphenyl] benzotriazole, 2
An ultraviolet absorber such as-[2'-hydroxy-3 ', 5'-bis (α, α-dimethylbenzyl) phenyl] 2H-benzotriazole and various known heat-fusible substances are used together as a sensitizer. be able to.

In particular, 2- (2'-hydroxy-5 '
-Methylphenyl) benzotriazole, 2- (2'-
Hydroxy-3 ', 5'-di-tert-butylphenyl)
-5-chloro-benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl)
-5-chloro-benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-aminophenyl) benzotriazole, 2- (2'-hydroxy-3', 5 '
-Di-tert-butylphenyl) benzotriazole, 2
-(2'-hydroxy-5'-tert-butylphenyl)
Benzotriazole, 2- (2'-hydroxy-5'-
tert-octylphenyl) benzotriazole, 2-
[2'-hydroxy-3 '-(3 ", 4", 5 ", 6"
-Tetra-hydrophthalimide-methyl) -5'-methylphenyl] benzotriazole, 2- [2'-hydroxy-3 ', 5'-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole It is preferable to use a benzotriazole-based ultraviolet absorber such as the above as a heat-fusible substance because the color density is high and the color is rapidly erased on the high temperature side. The amount of the heat-fusible substance contained in the recording layer is not necessarily limited, but is preferably 50 per 100 parts by weight of the basic dye.
To 500 parts by weight, more preferably 100 to 300 parts by weight.

As described above, in the present invention, a specific basic dye is used, but it is also possible to use a known basic dye in combination as long as the effect of the present invention is not impaired. Preparation of a coating liquid containing these, generally using water as a dispersion medium, a ball mill, an attritor, a stirrer / grinder such as a sand mill, the specific dye, the color former, the specific decolorizer,
It is prepared by adding a heat-fusible substance or the like as appropriate together or separately.

In such coating liquid, starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy group-modified polyvinyl alcohol, sulfo group-modified polyvinyl alcohol, acetoacetyl group-modified are usually used as binders. Polyvinyl alcohol, various modified polyvinyl alcohol such as silicone modified polyvinyl alcohol, styrene / maleic anhydride copolymer salt, styrene / acrylic acid copolymer salt, styrene
Butadiene copolymer emulsion, colloidal silica particle composite styrene / acrylic acid ester copolymer emulsion and the like are 2 to 40% by weight of the total solid content, preferably 5 to 2%.
About 5% by weight is blended. Of course, these binders may be used in combination of two or more.

In particular, styrene-maleic anhydride copolymer salt, styrene-acrylic acid copolymer salt, styrene
Butadiene copolymer emulsion, colloidal silica particle-combined styrene / acrylic acid ester copolymer emulsion, and among them, colloidal silica particle-combined styrene / acrylic acid ester copolymer emulsion is preferable because the stability of the paint over time is good. .

Further, various auxiliaries can be added to the coating liquid, for example, dioctylsulfosuccinic acid sodium salt, dodecylbenzenesulfonic acid sodium salt,
Examples thereof include dispersants such as lauryl alcohol sulfate / sodium salt and fatty acid metal salt, and other defoaming agents, fluorescent dyes, coloring dyes and the like.

Further, kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, fine anhydrous silica, in order to improve the adhesion of dust to the recording head,
Inorganic pigments such as activated clay, styrene microballs, nylon powder, polyethylene powder, urea / formalin resin filler, and organic pigments such as starch particles can also be added. Further, a dispersion liquid or emulsion of stearic acid, polyethylene, carnauba wax, paraffin wax zinc stearate, calcium stearate, ester wax or the like can be added so that sticking does not occur due to contact with a recording device or recording head.

The method for forming the recording layer is not particularly limited, and the recording layer can be formed according to a conventionally known and commonly used technique. For example, the coating liquid for the heat-sensitive recording layer is coated on a support with an appropriate coating device such as an air knife coater, a blade coater, a rod blade coater, a bar coater, a gravure coater, a curtain coater, and a die coater, and the recording layer is dried. To form. The coating amount of the coating liquid is also not particularly limited, and is generally 1.0 to 12 g / m ² in dry weight, preferably 1.5 to 10
It is adjusted in the range of g / m ² .

The multicolor thermosensitive recording medium of the present invention, as described above,
It is characterized by having a single thermosensitive coloring layer having a specific dye and a specific decoloring agent, but other coloring layers are not particularly limited as long as they develop different colors at different heating temperatures, and a basic dye Known coloring layers such as a color former, a diazonium salt and a coupler compound can be used. The order of stacking the layers is not particularly limited, and an intermediate layer may be provided between the color forming layers.

As the support, paper, plastic film, synthetic paper or the like is used. However, in order to clearly distinguish different color tones, the use of a highly smooth support is suitable. preferable. Of course,
A colored support may be used.

[0024]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Unless otherwise specified, "part" and "%" in the examples mean "part by weight" and "% by weight", respectively.

Example 1 Preparation of solution A 10 parts of 3-diethylamino-7-chlorofluorane,
A composition consisting of 5 parts of a 5% aqueous solution of methyl cellulose and 25 parts of water was pulverized with a sand mill until the average particle diameter became 0.9 μm.

Preparation of Solution B 4,4'-Cyclohexylidenediphenol 30 parts,
A composition consisting of 30 parts of a 5% aqueous solution of methyl cellulose and 70 parts of water was pulverized with a sand mill until the average particle diameter became 1.1 μm.

Preparation of Solution C 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide 10 parts, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole 20
Parts, methyl cellulose 5% aqueous solution 15 parts and water 80
The average particle size is 0.8μ in a sand mill.
It was crushed until it reached m.

Preparation of solution D Tetrakis (1,2,2,6,6-pentamethyl-4-
A composition consisting of 40 parts of piperidyl) -1,2,3,4-butanetetracarboxylate, 20 parts of a 5% aqueous solution of methylcellulose and 88 parts of water was pulverized with a sand mill until the average particle diameter became 1.0 μm.

[Preparation of Coating Liquid for High Temperature Thermosensitive Recording Layer] Liquid A 20
Part, B solution 65 parts, kaolin (trade name: UW-90, EM
C) 60 parts, 100 parts 20% aqueous solution of oxidized starch, water 1
55 parts were mixed and stirred to obtain a coating liquid.

[Preparation of coating liquid for intermediate layer] Silicon oxide pigment (trade name: Mizukasil P-527, oil absorption 170 cc / 10)
0 g, Mizusawa Chemical Co., Ltd.) 35 parts, 30% paraffin wax liquid (trade name: Hydrin P-7, Chukyo Yushi Co., Ltd.) 25
Parts, 10% polyvinyl alcohol aqueous solution 75 parts, water 11
5 parts were mixed and stirred to obtain a coating liquid.

[Preparation of coating liquid for low temperature heat sensitive recording layer] C liquid 12
5 parts, D solution 149 parts, B solution 130 parts, silicon oxide pigment (trade name: Mizukasil P-527, manufactured by Mizusawa Chemical Co., Ltd.) 20 parts,
20 parts of light calcium carbonate fine powder, 30 parts of colloidal silica particle composite styrene-acrylic acid ester copolymer emulsion (trade name: Movinyl 8200, solid content 44%, Hoechst Japan Co.), 20% aqueous solution of oxidized starch 4
0 parts, 30% zinc stearate dispersion 40 parts, water 125
The parts were mixed and stirred to obtain a coating liquid.

[Formation of Recording Layer] A synthetic paper having a basis weight of 60 g / m ² is coated with a coating solution for a high temperature heat sensitive recording layer, a coating solution for an intermediate layer and a coating solution for a low temperature heat sensitive recording layer in this order after drying. 7 each
Multi-color thermosensitive recording paper was obtained by applying and drying so as to have g / m ² , 3 g / m ² , and 4 g / m ^2, and applying a super calender.

Example 2 In preparation of solution C, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole was replaced by 2-
A multicolor thermosensitive recording paper was obtained in the same manner as in Example 1 except that [2'-hydroxy-3 ', 5'-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole was used.

Example 3 A multicolor thermosensitive recording paper was obtained in the same manner as in Example 1 except that 2- (2'-hydroxy-5'-methylphenyl) benzyltriazole was not used in the preparation of the liquid C.

Comparative Examples 1 to 2 Tetrakis (1,2,2,6,6-
In place of pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, α-triphenylguanidine (Comparative Example 1) and 1,3-di-o-tolylguanidine (Comparative Example 2) were used. Example 1 except that each was used
A multicolor thermosensitive recording paper was obtained in the same manner as.

Comparative Examples 3 to 4 In the preparation of C liquid, instead of 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide,
3- (4-diethylamino-2-ethoxy) phenyl-
3- (1-ethyl-2-methylindol-3-yl)
-4-Azaphthalide (Comparative Example 3) and 3- (4-diethylamino-2-ethoxy) phenyl-3- (1-octyl-2-methylindol-3-yl) -4-azaphthalide (Comparative Example 4) were each added. A multicolor thermosensitive recording paper was obtained in the same manner as in Example 3 except that it was used.

When the static color development characteristics of the thus obtained 7 kinds of multicolor color thermosensitive recording paper were examined, a blue color was obtained at a temperature of about 90 ° C. and a red color was obtained at a temperature of about 140 ° C. Was given. The recording density of blue color of the obtained multicolor thermosensitive recording paper was measured with a Macbeth densitometer (RD-914 type, blue filter, manufactured by Macbeth Co.), and the results are shown in Table 1.
It was shown to. In addition, Table 1 also shows the degree of blue / red color mixture during red color development.

[0038]

[Table 1]

Degree of blue / red color mixture ◯: Almost no bluish color, showing a clear red color. X: Blue and red are mixed, and it becomes blackish.

[0040]

INDUSTRIAL APPLICABILITY The multicolor heat-sensitive recording material of the present invention can obtain a recorded image having a clear color tone without color mixture or blurring, even though the basic dye and the decoloring agent are contained in the same layer. You can

Claims (1)

[Claims] 1. In a multicolor thermosensitive recording medium having two or more thermosensitive coloring layers each of which develops a different color tone on a support, one of the thermosensitive coloring layers is a basic dye. Bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, a coloring agent that shows a color reaction with the basic dye, and tetrakis (1,2,2) as a decoloring agent.
2,6,6-pentamethyl-4-piperidyl) -1,
A multicolor heat-sensitive recording material containing 2,3,4-butanetetracarboxylate.