JPH0284380A - Multicolor thermal recording material - Google Patents

Abstract

PURPOSE:To enable formation of a clear color tone image free of color mixing or bleeding by blending a specified decoloring agent. CONSTITUTION:At least one compound of formula I is incorporated in the title recording material at a position at which the compound can display a decoloring action to a color forming system comprising a leuco dye and a color reaction agent. In formula I, each of R1 to R3 is a 1-18C alkyl, 5-8C cycloalkyl, 7-9C aralkyl or 6-12C aryl, and R1 may further be a group of formula II (wherein each of R4 and R5 is hydrogen, a 1-18C alkyl, 5-8C cycloalkyl or 6-10C aryl which may have a halosubstd. or unsubstd. 1-5C alkyl). At least one of R1 to R5 is a cycloalkyl, aryl or aralkyl.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a multicolor thermosensitive recording material having a plurality of coloring layers each developing a different color tone.

"Prior Art" Conventionally, heat-sensitive recording utilizes a coloring reaction between a coloring agent and a coloring agent that develops color when it comes into contact with the coloring agent, and a colored image is obtained by bringing both coloring materials into contact with each other using heat. The body is well known. Such heat-sensitive recording media are relatively inexpensive, and the recording equipment is compact and relatively easy to maintain.
It is used not only as a recording medium for facsimiles and various computers, but also in a wide range of fields.

However, with the expansion of applications, the performance and quality required are also diversifying, such as higher intensity, image stabilization, multicolor recording, etc. In particular, since multicolor recording has a wide range of applications, a large number of recording materials have been researched and proposed.

Conventional multicolor recording materials can be roughly divided into the following two types. The first is a method in which the low-temperature heat-sensitive coloring layer develops color during low-temperature heating, and both the low-temperature heat-sensitive coloring layer and the high-temperature heat-sensitive coloring layer develop color during high-temperature heating to obtain a mixed color. The other method is to obtain the color tone of only the high-temperature thermosensitive coloring layer during high-temperature heating by using a decoloring agent that has a decoloring effect on the low-temperature coloring system during high-temperature heating in the first method above. It is. However, in the first method, the image becomes unclear and blurring occurs due to color mixture, so the second method is generally suitable as a method for obtaining a two-color image.

In the second method, various decolorizing agents are used,
Examples of decoloring agents that have a decoloring effect on color-forming systems consisting of basic leuco dyes and organic acidic substances include alkylene oxide adducts of bisphenols (Japanese Patent Application Laid-Open No. 139-1982).
741), ethylene oxide adduct of terephthalic acid (Japanese Patent Publication No. 55-25306), long chain 1,2-glycol (Japanese Patent Application Publication No. 55-27217), glycerin fatty acid ester (Japanese Patent Application Publication No. 55-113593) , urea derivatives (JP-A No. 55-139290), alkylene oxide adducts of linear glycols (JP-A No. 55-152094), morpholine derivatives (JP-A No. 56-40588), solid alcohols (JP-A No. 56-40588), 50-17865), polyether or polyethylene glycol derivatives (Japanese Patent Publication No. 50-1786)
7, Japanese Patent Publication No. 50-17868), nitrogen-containing crystalline organic compounds (Japanese Patent Publication No. 51-19991), guanidine derivatives (Japanese Patent Publication No. 51-29024), amines or quaternary ammonium salts (Japanese Patent Publication No. 50-1999) No. 18048) etc. have been proposed.

``Problem to be solved by the invention'' However, even when these decolorizing agents are used, it is not possible to sufficiently prevent color mixing and bleeding, and the current situation is that satisfactory results are not always obtained. .

Therefore, an object of the present invention is to provide a multicolor thermosensitive recording material that is capable of forming images with clear color tones without color mixing or bleeding by examining various decolorizing agents.

"Means for Solving the Problems" The above-mentioned object of the present invention is to have two or more heat-sensitive coloring layers each developing a different color tone, and at least one of the heat-sensitive coloring layers is colored with a leuco dye. By containing at least one compound represented by the following general formula in a multicolor thermosensitive recording medium containing a leuco dye and a coloring agent at a position capable of decolorizing the coloring system of the leuco dye and the coloring agent. achieved.

[In the formula, RI-R's is an alkyl group of 01 to 16, a cycloalkyl group of C3 to 8, an aralkyl group of C'l-9, or an aryl group of C, -, □ (with a halogen atom as a substituent) , a hydroxyl group, an alkyl group of CI to +8, an alkoxyl group of 02 to 5, or a hendiyl group), and R8 further represents R, -N - R3 (However, R and R5 are each hydrogen Atom, 01-II+
may have an alkyl group of Cs-11, a cycloalkyl group of Cs-11, or an alkyl group of C5-, which may be substituted with a halogen atom. . represents an aryl group. ). Incidentally, at least one of the substituents R8 to R3 is a cycloalkyl group, an atomyl group, or an aralkyl group. [Function] The thermosensitive recording material of the present invention has a small amount of the compound represented by the above general formula (both 1 and 1 It has an important feature in that it contains seeds.

Specific examples of the compound represented by the above general formula include the following compounds, but are of course not limited to these.

N-benzoyldicyclohexylamine, N-(4-methoxybenzoyl)dicyclohexylamine, N-(4
-ethoxybenzoyl)dibenzylamine, N-(4-
chlorobenzoyl) dibenzylamine, N-α-naphthoyldicyclohexylamine, N-β-naphthoyldicyclohexylamine, N-(2-phenylbenzoyl)
Dicyclohexylamine, N-(4-phenylbenzoyl)dicyclohexylamine, N-(2-hydroxy-
3-naphthoyl)dicyclohexylamine, N-(1-
hydroxy-2-naphthoyl)dicyclohexylamine, N-benzoyl-p,p-ditolylamine, N-benzoyl-β,β-dinaphthylamine, N-(benzophenone-2-carbonyl)dicyclohexylamine, N-
(benzophenone-4-carbonyl)dicyclohexylamine, N-(2-hydroxy-3-naphthoyl)cyclohexylmethylamine, N-(1-hydroxy-2-
naphthoyl)cyclohexylmethylamine, N-stearoyldicyclohexylamine, N-(4-ethoxybenzoyl)dicyclohexylamine, N-(4-n-propoxybenzoyl)dicyclohexylamine, N
(4-n-Butoxybenzoyl)dicyclohexylamine, N-(4-methylbenzoyl)dicyclohexylamine, N-(4-ethylbenzoyl)dicyclohexylamine, N-(4-n-propyldibenzoyl)dicyclohexylamine, N-( 4-n-butylbenzoyl)dicyclohexylamine, N-(4-tert-butylbenzoyl)dicyclohexylamine, N-(4-n
-octylbenzoyl)dicyclohexylamine, N
n-Propyl-N-cyclohexyl-N'-phenylurea, N,N-dicyclohexyl-N'-α-naphthylurea, N,N-dicyclohexyl-N'-β-naphthylurea, N- Methyl-N-cyclohexyl-N'-
α-naphthylurea, N-methyl-N-cyclohexyl-N'-β-naphthylurea, N-ethyl-N-phenyl-N'-α-naphthylurea, N-ethyl-N-phenyl-N'- β-naphthylurea, N-ethyl-N-phenyl-N'-(mtrifluoromethylphenyl)urea, N,N-dicyclohexyl-N'-stearylurea, etc.

Two or more of these compounds may be used in combination, and among these, those with a cyclohexyl group bonded to the N atom have a good decoloring effect, and are also highly hydrophobic, so they have a good effect on the storage stability of unrecorded paper. In particular, urea-based compounds having a cyclohexyl group on the N atom are most preferably used because they have excellent color erasing properties. These compounds are used in an amount of 0.1 to 20 times, preferably 0.5 to 10 times the total weight of the thermosensitive coloring basic dye and coloring agent to be decolored. is desirable.

In the multicolor thermosensitive recording material of the present invention, a position capable of decoloring action means a position where a decoloring reaction can occur between the thermosensitive coloring system to be decolored and the above-mentioned compound. This includes at least one of a protective layer, an intermediate layer, and an undercoat layer adjacent to the thermosensitive coloring layer that it contains, but especially when it is included in the intermediate layer, excellent effects on storage stability and decolorization can be obtained. This is the most preferred embodiment.

In addition, the above compound may be encapsulated in a capsule, and water,
It may be used after being dispersed in an organic solvent, oil, or the like.

Furthermore, it is also possible to use various conventionally known decolorizing agents in combination within a range that does not impair the effects of the present invention.

In the present invention, the combination of the color former and the color former contained in the color forming layer is not particularly limited, and any combination that causes a color reaction when the two come into contact with each other due to heat can be used. Examples include combinations of colorless or light-colored basic dyes and inorganic or organic acidic substances, and combinations of higher fatty acid metal salts such as ferric stearate and phenols such as gallic acid. Furthermore, various thermosensitive coloring layers capable of obtaining a colored image (recorded image) by heat, such as a thermosensitive coloring layer containing a combination of a diazonium compound, a coupler, and a basic substance, may be included as part of the structure.

However, since the specific color erasing agent of the present invention exhibits a color erasing effect on a coloring system consisting of a basic dye and an acidic substance, at least the coloring layer to be erased is composed of a basic dye and an acidic substance. It must be composed of a coloring system.

Various types of colorless to light-colored basic dyes are known, and examples include the following.

3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3,3-bis(p-dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl")-3-(1, 2-dimethylindole-3-
yl)phthalide, 3(p-dimethylaminophenyl)-
3-(2-methylindol-3-yl)phthalide, 3
．． 3-bis(1,2-dimethylindol-3-yl)
5-dimethylaminophthalide, 3,3-bis(1,2-
dimethylindol-3-yl)-6 dimethylaminophthalide, 3,3-bis(9-ethylcarbazole-3-
yl)-6-dimethylaminophthalide, 3,3-bis(
2-phenylindol-3-yl)-6-dimethylaminophthalide, 3-p-dimethylaminophenyl-3-
Triallylmethane dyes such as (1-methylpyrrol-3-yl)-6-dimethylaminophthalide, 4゜4'-bis-dimethylaminobenzhydrylbenzyl ether,
N-halophenyl-leukoolami 7, N-2,4,5
-g') Diphenylmethane dyes such as chlorophenyl leuco auramine, benzoyl leucomethylene blue, p
- Thiazine dyes such as nitrobenzoylleucomethylene blue, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho-( Spiro dyes such as 6'methoxybenzo) spiropyran and 3-propyl-spiro-dibenzopyran; lactam dyes such as rhodamine-B anilinolactam, rhodamine (p-nitroanilino) lactam, and rhodamine (0-chloroanilino) lactam;
3-dimethylamino-7-methoxyfluorane, 3-diethylamino-6-methoxyfluorane, 3-diethylamino-7-methoxyfluorane, 3-diethylamino-
7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7,
8-Benzofluorane, 3-diethylamino-5-methyl-7-dibenzylaminofluorane, 3-diethylamino-6,7-dimethylfluorane, 3-(N-ethyl-p-)luidino)-7- Methylfluoran, 3-diethylamino-7-N-acetyl-N-methylaminofluorane, 3-diethylamino-7-N-methylaminofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino- ? -N-methyl-N
-benzylaminofluorane, 3-diethylamino-7
-N-chloroethyl-N-methylaminofluorane, 3
-diethylamino-7-N-diethylaminofluorane, 3-(N-ethyl-p-)luidino)=6-methyl-
7-phenylaminofluorane, 3(N-cycloben-N-ethylamino)-6-methyl-7-anilinofluorane, 3-(N-ethyl-p-)luidino)-6-
Methyl-7(p-toluidino)fluoran, 3-diethylamino-6-methyl-7-phenylaminofluoran, 3-diethylamino-7-(2-carbomethoxy-phenylamino)fluoran, 3-(N-ethyl-N -isoamylamino)-6-methyl-7-phenylaminofluorane, 3-(N-cyclohexyl-N-methylamino)-6-methyltwophenylaminofluorane, 3-
Pyrrolidino-6-methyl-7-phenylaminofluorane, 3-piperidino-6-methyl-7-phenylaminofluorane, 3-diethylamino-6-methyl-7-xylidinofluorane, 3-diethylamino-7-( 0-
chlorophenylamino)fluoran, 3-dibutylamino-7-(0-chlorophenylamino)fluoran, 3
-pyrrolidino-6methyl-7-p-butylphenylaminofluorane, 3-N-methyl-N-tetrahydrofurfurylamino-6-methyl-7-anilinofluorane,
3-N-ethyl-N-tetrahydrofurfurylamino-
Fluoran dyes such as 6-methyl-7-anilinofluorane, etc.

Various types of inorganic or organic acidic substances that develop color upon contact with basic dyes are known, and examples thereof include the following.

Inorganic acidic substances such as activated clay, acid clay, acpulgite, bentonite, colloidal silica, aluminum silicate, 4-tert-butylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, 4
-Hydroxyacetophenone, 4-tert-octylcatechol, 2,2'-dihydroxydiphenyl, 2.
2'-methylenebis(4-methyl-6-tert-isobutylphenol), 4.4'-isopropylidenebis(2-tert-butylphenol), 4. 4'-5
ee-butylidene diphenol, 4-phenylphenol, 4,4'-isopropylidene diphenol (bisphenol A), 2,2'-methylenebis (4-chlorophenol), hydroquinone, 4,4'-cyclohexylidene diphenol, Phenolic compounds such as benzyl 4-hydroxybenzoate, dimethyl 4-hydroxyphthalate, hydroquinone monobenzyl ether, 4-hydroxyphenyl-4'-isopropyloxyphenyl sulfone, novolac type phenolic resin, phenol polymer, benzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, 3-sec-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-benzylsalicylic acid, 3-(α-methylbenzyl)salicylic acid, 3-chloro-5-(α-methylbenzyl)salicylic acid, 3.5-di-tert-butylsalicylic acid, 3-phenyl-5 −
Aromatic carboxylic acids such as (α,α-dimethylbenzyl)salicylic acid and 3,5-di-α-methylbenzylsalicylic acid, and their phenolic compounds, aromatic carboxylic acids such as zinc, magnesium, aluminum, calcium, titanium, Examples include existing acidic substances such as salts with polyvalent metals such as manganese, tin, and nickel.

In the leisurely recording medium of the present invention, the ratio of the coloring agent and coloring agent used in the coloring layer is appropriately selected depending on the type of coloring agent and coloring agent used, and is not particularly limited. For example, when using a basic colorless dye and an acidic substance,
Generally, from 1 to 50 parts by weight, preferably from 1 to 10 parts by weight, of the acidic substance are used per part by weight of the basic colorless dye.

To prepare a coating solution containing these substances, generally, water is used as a dispersion medium, and the coloring agent and the coloring agent are dispersed together or separately using a ball mill, an attritor sand mill, etc., and then the coating solution is prepared. prepared.

Such coating liquids usually contain starches and binders as binders.
Hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, gelatin, casein, gum arabic, polyvinyl alcohol, diisobutylene/maleic anhydride copolymer salt, styrene/maleic anhydride copolymer salt, ethylene/acrylic acid copolymer salt, styrene/
Acrylic acid copolymer salt, natural rubber emulsion, styrene/butadiene copolymer emulsion, acrylonitrile/butadiene copolymer emulsion, methyl methacrylate/butadiene copolymer emulsion, polychloroprene emulsion, vinyl acetate emulsion, ethylene/vinyl acetate emulsion etc. is 10 to 7 of the total solid content.
0% by weight, preferably 15-50% by weight. Furthermore, various auxiliary agents can be added to the coating liquid.

For example, dispersants such as sodium dioctyl sulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, alginates, fatty acid metal salts, ultraviolet absorbers such as benzophenone and triazole, and other foaming agents. , fluorescent dyes, colored dyes, and the like.

In addition, lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, and ester wax, calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide,
=m+ti materials such as silicon dioxide, aluminum hydroxide, barium sulfate, zinc sulfate, talc, kaolin, clay, calcined resin, colloidal silica, styrene microholes, nylon powder, polyethylene powder, urea/formalin resin filler, raw starch granules Organic pigments such as stearic acid amide, stearic acid methylene bisamide, oleic acid amide, palmitic acid amide, fatty acid amides such as coconut fatty acid amide, 2.2゛-methylenebis(4-methyl-6-tert-butylphenol), 4 .4'-
Hindered phenols such as butylidene bis(6-tert-butyl-3-methylphenol), 1,1゜3-tris(2-methyl-4-hydroxy-5-tert-butylphenol)butane, dibenzyl terephthalate, 1゜2-di(3-methylphenoxy)ethane, 1,
2-diphenoxyethane, 4,4'-ethylenedioxy-bis-benzoic acid diphenylmethyl ester and various known thermofusible substances can also be used in combination.

When an inorganic or organic pigment is contained in the coloring layer, it is preferable to use a pigment with a particle size as small as possible, and it is particularly desirable to use a pigment with an average particle size of 2 μm or less.

In the heat-sensitive recording material of the present invention, the method of forming the coloring layer is not particularly limited, and can be formed according to conventionally well-known and commonly used techniques, such as air knife coating, blade coating, etc. to support the coating liquid. It is formed by applying it on the body and drying it. Further, the amount of coating liquid to be applied is not particularly limited, but is generally 1.5 to 12 g/n in terms of dry weight. It is adjusted within a range of degrees.

In addition, the support is not particularly limited, and paper such as high-quality paper, base paper made with a Yankee machine, single-sided glossy base paper, double-sided glossy base paper, cast coated paper, art paper, coated paper, medium-quality coated paper, etc. etc., synthetic fiber paper, synthetic resin film, etc. are used as appropriate.

In addition, after coating and drying the coloring layer, smoothing treatment such as super calendering can be performed as necessary. Furthermore, it is possible to provide an overcoat layer on the color-forming layer for the purpose of protecting the color-forming layer, etc., and various known techniques in the heat-sensitive recording field can be added, such as providing an undercoat layer or an N coating layer on the support. It's something you get.

11 In the heat-sensitive recording material of the present invention, among the two or more heat-sensitive color-forming layers each forming a different color tone formed as described above, in particular, a color-forming layer containing a color-forming system of a leuco dye and a coloring agent. In contrast, a specific decolorizing agent is contained in a position where it can act as a decoloring agent, but for example, when a decoloring agent is contained in a coloring layer containing the coloring system, it is necessary to simply remove the coloring layer from the coloring layer. A decoloring agent may be added to the coating liquid to be formed. Also,
For example, when the coloring system is contained in the protective layer 311 or undercoat layer adjacent to the coloring layer containing the coloring system, a decoloring agent may be added to the coating liquid constituting the protective layer or the undercoat layer. Of course, it is also possible to apply a coating liquid mainly composed of a decolorizing agent as the decolorizing agent layer, and it goes without saying that various variations are possible without exceeding the gist of the present invention. In addition, various variations are possible in the color-forming materials and color tones constituting each color-forming layer of the multicolor thermosensitive recording material, and can be appropriately selected depending on the intended multicolor thermosensitive recording material. .

The heat-sensitive recording material of the present invention thus obtained is an extremely excellent multicolor heat-sensitive recording material that can obtain recorded images with clear color tones without color mixing or bleeding.

"Example" The present invention will be described in more detail with reference to Examples below, but the present invention is of course not limited to these.

Further, unless otherwise specified, parts and % in the examples indicate parts by weight and % by weight, respectively.

Example I Solution A Preparation 3-diethylamino-7,8-benzofluorane

10 parts methylcellulose 5% aqueous solution
5 parts water
25 parts This composition was milled with a sand mill until the average particle size was 3 μm.
It was crushed until it was.

Preparation of Solution B 3-(N-Cyclohexyl-N-methylamino)6-methyl-7-phenylaminofluorane 10 parts Dibenzyl terephthalate 20 parts Methylcellulose 5% aqueous solution 15 parts Water
80 parts of this composition was ground in a sand mill until the average particle size was 3 μm.

C Lacquer Preparation 4.4'-Cyclohexylidene diphenol 30 parts Methylcellulose 5% aqueous solution 30 parts water
70 parts of this composition was ground in a sand mill until the average particle size was 3 μm.

Preparation of Solution D N-α-naphthoyldicyclohexylamine 50 parts Methylcellulose 5% aqueous solution 25 parts Water
110 parts of this composition was ground in a sand mill until the average particle size was 3 μm.

[Preparation of coating liquid for high temperature heat-sensitive recording layer]

40 parts of liquid A, 130 parts of liquid C, 30 parts of silicon oxide pigment (trade name: Mizukasil P-527, manufactured by Mizusawa Chemical Co., Ltd.), 75 parts of 20% oxidized starch aqueous solution, and 70 parts of water were mixed and stirred to prepare a coating liquid. .

[Preparation of coating liquid for low-temperature heat-sensitive recording layer]

125 parts of liquid B, 130 parts of liquid C, silicon oxide pigment (product name:
A coating liquid was prepared by mixing and stirring 30 parts of Mizukashiru P-527), 150 parts of a 20% oxidized starch aqueous solution, and 55 parts of water.

[Preparation of coating liquid for decolorizing layer]

185 parts of Liquid D and 50 parts of a 20% oxidized starch aqueous solution were mixed and stirred to prepare a coating liquid.

[Preparation of coating liquid for intermediate layer]

A coating liquid was prepared by mixing and stirring 100 parts of a 10% polyvinyl alcohol aqueous solution, 20 parts of kaolin, and 50 parts of water.

[Formation of recording layer]

High-temperature heat-sensitive recording layer coating liquid was applied to high-quality paper with a basis weight of 50 g/m.
Coating liquid for intermediate layer, coating liquid for erasing layer, and coating liquid for low-temperature heat-sensitive recording layer, in this order, the coating amount after drying is 6 g/durable and 3 g, respectively.
/resistant, 4g/resistant, 3g/n? The mixture was coated and dried, and then subjected to super calendering to obtain a two-color thermosensitive recording paper.

Example 2 Two-color thermosensitive recording in the same manner as in Example 1 except that N-(2-hydroxy-3-naphthoyl)dicyclohexylamine was used instead of N-α-naphthoyldicyclohexylamine in preparing liquid D. Got paper.

Example 3 In the preparation of solution D, N-(4-methoxybenzoyl) was used instead of N-α-naphthoyldicyclohexylamine.
A two-color thermosensitive recording paper was obtained in the same manner as in Example 1 except that dicyclohexylamine was used.

Example 4 In the preparation of solution D, N,N-dicyclohexyl-N' was used instead of N-α-naphthoyldicyclohexylamine.
A two-color thermosensitive recording paper was obtained in the same manner as in Example 1 except that -α-naphthylurea was used.

Example 5 In the preparation of solution D, N,N-dicyclohexyl-N' was used instead of N-α-naphthoyldicyclohexylamine.
A two-color thermosensitive recording paper was obtained in the same manner as in Example 1 except that , N'-diphenylurea was used.

Comparative Example I A two-color thermosensitive recording paper was prepared in the same manner as in Example 1, except that 1,2-(4'-morpholinodithio)benzothiazole was used instead of N-α-naphthoyldicyclohexylamine in the preparation of liquid D. I got it.

The dynamic coloring properties of the six types of two-color thermosensitive recording papers thus obtained were tested in the following manner.

[Recording conditions]

Using a thermal printer (PS-8600, manufactured by ROHM Co., Ltd.), thermal head = 8 dots/mu, heating resistance:
Approximately 1300Ω/dot, main scanning recording speed: 20 m5e
c/1ine, sub-scanning: 321ine/m, head 0.44W/dot, low temperature coloring energy: 0
．． Recording was performed under the conditions of 26 mJ and high temperature coloring energy: 1.06 mJ.

The density of the recorded area was measured using a Macbeth densitometer (manufactured by Macbeth, Model RD914) using a visual filter for low-temperature colored images (black) and a green filter for high-temperature colored images (red). , the results are shown in the table.

Furthermore, in order to check the degree of color mixture in the high-temperature color image, the density of the blue component was measured using a red filter, and the results are also listed in the table. Note that the smaller this number is, the more vivid the red color is.

"Effects" The colored images of the two-color thermosensitive recording paper obtained in each example were extremely clear without color mixture or bleeding, but in the recording paper of the comparative example, color mixture occurred and the clarity was significantly lacking.

table

Claims (1)

[Scope of Claims] A multicolor thermosensitive recording material having two or more thermosensitive coloring layers each developing a different color tone, and at least one of the thermosensitive coloring layers containing a leuco dye and a coloring agent, A multicolor thermosensitive recording material, characterized in that at least one compound represented by the following general formula is contained in a position capable of decolorizing a coloring system of a leuco dye and a coloring agent. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, R_1 to R_3 are C_1_ to _1_8, respectively.
alkyl group, C_5_-_8 cycloalkyl group, C
Aralkyl group of _7_ to _9, or C_6_ to _1_2
Aryl group (substituents include halogen atom, hydroxyl group, alkyl group of C_1_ to_1_8, C_2_ to__
5), and R_1 further includes ▲numerical formulas, chemical formulas, tables, etc.▼ (However, R_4 and R_5 are hydrogen atoms, C_1_
~_1_0 alkyl group, C_5_-_8 cycloalkyl group, or C_1_ which may be substituted with a halogen atom
C_6_~_1_0 which may have ~_5 alkyl groups
represents an aryl group. ). Note that at least one of the substituents R_1 to R_5 is a cycloalkyl group, an aryl group, or an aralkyl group. ]