JPH04329178A - Multi-color thermal recording medium - Google Patents

Abstract

PURPOSE:To provide a multi-color thermal recording medium capable of forming a sharp color image free from a motley color fog peculiar to a low-temperature developed color image and with high recording sensitivity as a high-temperature developed color image. CONSTITUTION:The multi-color thermal recording medium consists of at least, a high-temperature color development layer, an intermediate layer and a low- temperature color development layer laminated sequentially. In addition, the color development layers contain leuco color comprising leuco dye and a color developer. The intermediate layer contains inorganic pigment and an adhesive as main ingredients and has a haze value of 65% or lower.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a multicolor thermosensitive recording material having a plurality of coloring layers each developing a different color tone.

0002

[Prior Art] Conventionally, heat-sensitive recording utilizes a color-forming reaction between a color-forming agent and a color-forming agent that develops color when it comes into contact with the color-forming agent, and a color-forming image is obtained by bringing both color-forming substances into contact with heat. The body is well known. Such heat-sensitive recording media are relatively inexpensive, the recording equipment is compact, and maintenance is relatively easy, so they are used not only as recording media for facsimiles and various computers, but also in a wide range of fields. With the expansion of applications, the performance and quality required of these thermosensitive recording media have diversified, such as increased sensitivity, image stabilization, and multicolor recording. In particular, since multicolor recording has a wide range of applications, a large number of recording materials have been researched and proposed to date.

Conventional two-color heat-sensitive recording materials can be broadly classified into the following two types. The first is a method in which the low-temperature coloring layer develops color during low-temperature heating, and both the low-temperature coloring layer and the high-temperature coloring layer develop color during high-temperature heating to obtain a mixed color image (additive coloring method).
Another method is to use a decoloring agent that has a decoloring effect on the low-temperature color-forming system during high-temperature heating in the above method, thereby obtaining a color tone of only the high-temperature color-forming layer during high-temperature heating ( color erasure method).

Of the above two methods, the color erasing method has been put into practical use to some extent as it has become possible to obtain clear two-color images without bleeding due to the development of effective color erasing agents and improvements in the layer structure. However, since a decolorizing agent is used, the storage stability of images after recording is difficult, and as a result, the range of use is currently limited. Furthermore, when looking at the storage stability of images, the first additive coloring method is excellent, but it is accompanied by the problem that the high-temperature coloring layer inevitably becomes partially colored during low-temperature heating, resulting in images becoming cloudy and lacking clarity.

[0005]

[Problems to be Solved by the Invention] The present invention improves the above-mentioned problems in the additive coloring method, so that the high-temperature coloring layer hardly develops color when heated at low temperatures, and also has good coloring sensitivity and clear color when heated at high temperatures. The object of the present invention is to provide a multicolor thermosensitive recording material capable of forming a toned image.

[0006]

[Means for Solving the Problems] The present invention provides a leuco coloring layer comprising at least a high temperature coloring layer, an intermediate layer, and a low temperature coloring layer laminated on a support, the coloring layer containing a leuco dye and a coloring agent. The present invention is a multicolor thermosensitive recording material that is a layer, in which the intermediate layer contains an inorganic pigment and an adhesive as main components, and has a haze value of 65% or less.

[0007]

[Effect] In order to obtain clear images when heated at low temperatures, it is necessary to eliminate color mixing fog caused by partial color development in the high temperature coloring layer. It is necessary to have color development sensitivity. Therefore, in the multicolor thermosensitive recording material of the present invention, an intermediate layer having the above-mentioned specific properties is formed between the high temperature coloring layer and the low temperature coloring layer.

[0008] Multicolor thermosensitive recording materials are known in which an intermediate layer containing various adhesives or pigments as main components is provided between a high-temperature coloring layer and a low-temperature coloring layer. The coatability is poor, and the effect as an intermediate layer is also insufficient. Furthermore, with an intermediate layer containing a normal pigment, although the clarity of a low-temperature colored image is improved, sufficient recording sensitivity of the high-temperature coloring layer cannot be obtained when heated at a high temperature. Therefore, in the multicolor thermosensitive recording material of the present invention, the haze value of the intermediate layer containing an inorganic pigment and an adhesive as main components is specified to be 65% or less. When such a specific intermediate layer is formed, the clarity of the low-temperature coloring image is significantly improved, and the sensitivity of the high-temperature coloring layer is also sufficiently improved, resulting in a clear multicolor image.

In the multicolor thermosensitive recording material of the present invention, the haze value (haze value, haze, turbidity) of the intermediate layer is determined by applying the intermediate layer forming coating liquid to transparent polypropylene in the same coating amount as the intermediate layer to be formed. A sample for measurement is prepared by coating and drying on a film, and its haze value is measured using a haze meter (for example, TC-HII manufactured by Tokyo Denshoku Co., Ltd.) according to JIS K6714 method.
Defined by the value measured in I).

The type of inorganic pigment contained in the intermediate layer is not particularly limited as long as the intermediate layer has a specific haze value as described above, but kaolin and colloidal silica with an average particle size of 1 μm or less have a particularly low haze value. It is most preferably used to give a value. The proportion of the inorganic pigment contained in the intermediate layer is 30 to 30% of the total solid content of the intermediate layer.
It is desirable to adjust the amount within a range of about 80% by weight, and in order to obtain a suitable barrier effect, it is desirable to adjust the coating amount of the intermediate layer within a range of about 1 to 5 g/m@2 in terms of dry weight.

Specific examples of adhesives that are other components forming the intermediate layer include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, diisobutylene/maleic anhydride, etc. Polymer 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 Examples include a combined emulsion, a methyl methacrylate/butadiene copolymer emulsion, a polychloroprene emulsion, a vinyl acetate emulsion, an ethylene/vinyl acetate emulsion, and these are blended in an amount of about 20 to 70% by weight of the total solid content of the intermediate layer.

Among the adhesives mentioned above, polyvinyl alcohol derivatives are particularly preferred, such as completely saponified or partially saponified polyvinyl alcohol, acetoacetylated polyvinyl alcohol into which an acetoacetyl group is introduced by reacting polyvinyl alcohol with diketene, etc. , carboxy-modified polyvinyl alcohol obtained as a saponified copolymer of vinyl acetate and ethylenically unsaturated carboxylic acids such as maleic acid, fumaric acid, itaconic acid, crotonic acid, acrylic acid, and methacrylic acid, silicon-modified polyvinyl alcohol , sulfonic acid-modified polyvinyl alcohol obtained as a saponified copolymer of vinyl acetate and an olefin sulfonic acid or its salt such as ethylene sulfonic acid or allyl sulfonic acid, vinyl acetate and ethylene, propylene, isobutylene, α-octene , olefin-modified polyvinyl alcohol obtained by saponifying copolymers with olefins such as α-dotecene and α-octadodecene, and saponified products of copolymers of vinyl acetate and nitriles such as acrylonitrile and methacrylonitrile. nitrile-modified polyvinyl alcohol obtained by saponifying a copolymer of vinyl acetate and amides such as acrylamide or methacrylamide; and amide-modified polyvinyl alcohol obtained by saponifying a copolymer of vinyl acetate and N-vinylpyrrolidone. Examples include pyrrolidone-modified polyvinyl alcohol.

Furthermore, the paint that forms the intermediate layer for crosslinking the adhesive component contains glyoxal, methylolmelamine, potassium persulfate, ammonium persulfate, sodium persulfate, ferric chloride, magnesium chloride, boric acid, A curing agent such as ammonium chloride may be added, and if necessary, other auxiliary agents such as sodium dioctyl sulfosuccinate, sodium dodecylbenzene sulfonate, sodium lauryl alcohol sulfate,
Dispersants such as alginates and fatty acid metal salts, ultraviolet absorbers such as benzophenone and triazole, lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, and ester wax, stearamide, and methylene stearate. Fatty acid amides such as bisamide, oleic acid amide, palmitic acid amide, matcha oleic acid amide, coconut fatty acid amide, 2,2'-methylenebis(4-methyl-6-
tert-butylphenol), 4,4'-butylidenebis(6-tert-butyl-3-methylphenol)
, 1,1,3-tris(2-methyl-4-hydroxy-
Hindered phenols such as (5-tert-butylphenol) butane, dibenzyl terephthalate, 1,2-
Diphenoxyethane, p-benzylbiphenyl, 1-hydroxy-2-naphthoic acid phenyl ester, 4,4'
-ethylenedioxy-bis-benzoic acid diphenylmethyl ester, oxalic acid di-p-methylbenzyl ester,
A thermofusible substance such as di-p-chlorobenzyl oxalate, an antifoaming agent, a fluorescent dye, a coloring dye, etc. can also be added as appropriate.

The coloring layer constituting the recording medium of the present invention is a leuco coloring layer containing a leuco dye and a coloring agent,
Useful colorless to light-colored leuco dyes include, for example, 3
, 3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3,3-bis(p-dimethylaminophenyl)phthalide, 3-(4-dimethylaminophenyl)-3-(1,2- Dimethylindol-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
-(1-methylpyrrol-3-yl)-6-dimethylaminophthalide and other triallylmethane dyes, 4,4'-
Bis-dimethylaminobenzhydrylbenzyl ether, N-halophenyl-leucoolamine, N-2,4,
Diphenylmethane dyes such as 5-trichlorophenylleucoauramine, benzoylleucomethylene 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-( 6'-methoxybenzo)
spiro dyes such as spiropyran, 3-propyl-spiro-dibenzopyran, rhodamine-B anilinolactam,
Lactam dyes such as rhodamine (p-nitroanilino) lactam and rhodamine (o-chloroanilino) lactam, 3-cyclohexylamino-6-chlorofluoran,
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-toluidino)-7-methyl Fluoran, 3-diethylamino-7-N-acetyl-N-methylaminofluorane, 3-diethylamino-7-N-methylaminofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7 -N-methyl-
N-benzylaminofluorane, 3-diethylamino-
7-N-chloroethyl-N-methylaminofluorane,
3-diethylamino-7-N-diethylaminofluorane, 3-(N-ethyl-p-toluidino)-6-methyl-7-phenylaminofluorane, 3-(N-cyclopentyl-N-ethylamino)-6- Methyl-7-anilinofluorane, 3-(N-ethyl-p-toluidino)-
6-Methyl-7-(p-toluidino)fluoran, 3-
Diethylamino-6-methyl-7-phenylaminofluorane, 3-dibutylamino-6-methyl-7-phenylaminofluorane, 3-dipentylamino-6-methyl-7-phenylaminofluorane, 3-diethylamino-7 -(2-carbomethoxy-phenylamino)fluorane, 3-(N-ethyl-N-isoamylamino)-
6-Methyl-7-phenylaminofluorane, 3-(N
-cyclohexyl-N-methylamino)-6-methyl-
7-phenylaminofluorane, 3-pyrrolidino-6-
Methyl-7-phenylaminofluorane, 3-piperidino-6-methyl-7-phenylaminofluorane, 3-
Diethylamino-6-methyl-7-xylidinofluorane, 3-diethylamino-7-(o-chlorophenylamino)fluoran, 3-dibutylamino-7-(o-chlorophenylamino)fluoran, 3-pyrrolidino-6
-methyl-7-p-butylphenylaminofluorane,
3-N-methyl-N-tetrahydrofurfurylamino-
Examples include fluoran dyes such as 6-methyl-7-anilinofluorane and 3-(N-ethyl-N-tetrahydrofurfurylamino)-6-methyl-7-anilinofluorane.

In the multicolor thermosensitive recording material of the present invention, the color tone of the coloring layer is appropriately adjusted by selecting various leuco dyes as described above. A coloring system is preferably used, and a coloring system that produces green, purple, black, etc. by color mixing with a low temperature coloring image is preferably used for the high temperature thermosensitive coloring layer. In particular, if a black coloring system is used in the high temperature thermosensitive coloring layer, a clear color tone can be obtained.
-diethylamino-6-methyl-7-phenylaminofluorane, 3-dibutylamino-6-methyl-7-phenylaminofluorane, 3-dipentylamino-6-methyl-7-phenylaminofluorane, 3-(N -ethyl-N-isoamylamino)-6-methyl-7-phenylaminofluorane, 3-(N-cyclohexyl-N-
methylamino)-6-methyl-7-phenylaminofluorane, 3-(N-ethyl-N-tetrahydrofurfurylamino)-6-methyl-7-phenylaminofluorane, 3-(N-ethyl-p- Toluidino-6-methyl-7-phenylaminofluoran, 3-dibutylamino-7-(o-chlorophenylamino)fluoran, and the like are preferably used in the high temperature thermosensitive coloring layer.

Various types of inorganic or organic acidic substances that develop color upon contact with the various leuco dyes mentioned above are also known, such as activated clay, acid clay, attapulgite,
Bentonite, colloidal silica, inorganic acidic substances such as aluminum silicate, 4-tert-butylphenol, 4
-Hydroxydiphenoxide, α-naphthol, β-naphthol, 4-hydroxyacetophenol, 4-te
rt-octylcatechol, 2,2'-dihydroxydiphenol, 2,2'-methylenebis(4-methyl-6
-tert-isobutylphenol), 4,4'-isopropylidene bis(2-tert-butylphenol)
, 4,4'-sec -butylidene diphenol, 4-
Phenylphenol, 4,4'-isopropylidenediphenol (bisphenol A), 2,2'-methylenebis(4-chlorophenol), hydroquinone, 4,4
'-Cyclohexylidene diphenol, benzyl 4-hydroxybenzoate, dimethyl 4-hydroxyphthalate,
Hydroquinone monobenzyl ether, 4-hydroxyphenyl-4'-isopropyloxyphenylsulfone, 4,4'-dihydroxydiphenylsulfone, 2,
Phenolic compounds such as 4'-dihydroxydiphenylsulfone, 3,4-dihydroxy-4'-methyldiphenylsulfone, novolac type phenolic resin, phenol polymer, benzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthal acid, 3-sec
-Butyl-4-hydroxybenzoic acid, 3-cyclohexyl-4-hydroxybenzoic acid, 3,5-dimethyl-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-
Chlor-5-(α-methylbenzyl)salicylic acid, 3,
5-di-tert-butylsalicylic acid, 3-phenyl-
5-(α,α-dimethylbenzyl)salicylic acid, 3,5
- Aromatic carboxylic acids such as di-α-methylbenzylsalicylic acid, and their phenolic compounds; salts of aromatic carboxylic acids and polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, and nickel; Examples include organic acidic substances such as.

[0017] The ratio of the leuco dye to the coloring agent is adjusted appropriately depending on the type of materials used, but generally it is 1 to 50 parts by weight, preferably 1 to 10 parts by weight, per 1 part by weight of the leuco dye. A coloring agent of about 100% is used. In addition, various thermofusible substances such as those mentioned above can be blended into the coating liquid that forms the coloring layer.In particular, the higher the sensitivity of the low-temperature coloring layer, the greater the difference in coloring energy from the high-temperature coloring layer. As a result, the clarity of the multicolor image is improved, so it is preferable to incorporate such an auxiliary agent into the low-temperature coloring layer.

[0018] Incidentally, attempts have been made to incorporate a thermofusible substance with a low melting point into the low-temperature coloring layer, but this may be because the thermofusible substance with a low melting point permeates into the high-temperature coloring layer. However, during low-temperature heating, the occurrence of fog due to color development in the high-temperature coloring layer was unavoidable. However, in the heat-sensitive recording material of the present invention, since the specific intermediate layer as described above is formed, this intermediate layer may exert a sufficient barrier effect against thermofusible substances, but the high-temperature coloring layer No color fog occurs at all, and extremely clear multicolor images can be obtained. Therefore, a thermofusible substance having a low melting point of 70-120°C, preferably 75-100°C, most preferably 75-90°C can be incorporated into the low-temperature coloring layer. Specific examples of thermofusible substances with such low melting points include:
For example, p-benzylbiphenyl (85°C), 1-(2-
methylphenoxy)-2-(4-methoxyphenoxy)
Ethane (83℃), oxalic acid dibenzyl ester (80℃)
~81°C).

Further, the above-mentioned adhesive is added to the coating liquid for forming the coloring layer in an amount of about 15 to 50% by weight based on the total solid content. Furthermore, for example, diatomaceous earth, calcined diatomaceous earth, kaolin, calcined kaolin, white carbon, magnesium carbonate, calcium carbonate, zinc oxide, aluminum oxide,
Inorganic pigments such as titanium oxide, silicon oxide, aluminum hydroxide, barium sulfate, zinc sulfate, talc, clay, calcined clay, styrene microballs, nylon powder, polyethylene powder, urea/formalin resin filler,
Organic pigments such as raw starch granules may be added, and various auxiliary agents such as dispersants, lubricants, antifoaming agents, ultraviolet absorbers, fluorescent dyes, and colored dyes may also be blended as appropriate.

[0020] Coloring layer-forming coating liquids containing these substances are generally prepared using water as a dispersion medium and using an appropriate stirring or grinding machine such as a ball mill, attritor, or sand mill. In addition, the coating amount of the coloring layer forming coating liquid is generally 1 to 10% by dry weight.
About 12g/m2, preferably 1.5-7g/m2
It is adjusted within a range of degrees.

In the multicolor thermosensitive recording material of the present invention, the method of forming the coloring layer and the intermediate layer is not particularly limited, and they can be formed according to conventionally well-known and commonly used techniques, such as air knife coating, blade coating, etc. It is formed by coating and drying on a support. Also,
The support is not particularly limited, and examples include papers 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, and synthetic paper. Fiber paper, synthetic resin film, etc. are used as appropriate. Furthermore, after coating and drying the coloring layer, smoothing treatment such as supercalendering can be performed as necessary.

Of course, various variations are possible within the scope of the gist of the present invention. For example, an overcoat layer may be provided on the coloring layer for the purpose of protecting the coloring layer, or an undercoat layer or an undercoat layer may be provided on the support. Various known techniques in the field of heat-sensitive recording materials, such as providing a backing layer, can be added as appropriate. Also,
Various variations are possible in the color-forming material and color tone constituting each color-forming layer, and can be appropriately selected depending on the intended multicolor thermosensitive recording material.

[0023]

[Examples] The present invention will be explained 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 1 Preparation of Solution A 10 parts of 3-dibutylamino-6-methyl-7-phenylaminofluorane 5% aqueous solution of methylcellulose
Part 5 Water


25 parts of this composition was ground in a sand mill until the average particle size was 1.5 μm. Preparation of B solution 4,4'-isopyrrolidendiphenol
30
Part 5% aqueous solution of methylcellulose

30 parts water

70 parts of this composition was ground in a sand mill until the average particle size was 1.5 μm. Preparation of liquid C 3-diethylamino-7-chlorofluorane
10 copies
1,2-di(3-methylphenoxy)ethane
20 copies
5% aqueous solution of methylcellulose

Part 15 Water

80 parts of this composition was ground in a sand mill until the average particle size was 1.5 μm.

[Preparation of high-temperature color forming layer forming coating solution] 40 parts of liquid A, 130 parts of liquid B, silicon oxide pigment (trade name: Mizukashiru)
P-527 (manufactured by Mizusawa Chemical Co., Ltd.), 30 parts of a 20% oxidized starch aqueous solution, and 54 parts of water were mixed and stirred to prepare a coating liquid. [Preparation of low-temperature color forming layer forming coating solution] 125 parts of liquid C, 13 parts of liquid B
0 parts, silicon oxide pigment (trade name: Mizukasil P-52
7, Mizusawa Chemical Co., Ltd.) 10 parts, 20% oxidized starch aqueous solution 5
0 parts and 85 parts of water were mixed and stirred to prepare a coating liquid. [Preparation of intermediate layer forming coating liquid] 32 parts of kaolin (trade name: UW-90, average particle size 0.8 μm, manufactured by EMC), 8% acetoacetylated polyvinyl alcohol (trade name: Gosefimer Z-200) , manufactured by Nippon Gosei Kagaku Co., Ltd.) and 243 parts of water were mixed and stirred to prepare a coating liquid.

[Manufacture of multicolor thermosensitive recording material] Basis weight 50 g/m
2. On top of the high-quality paper, apply the coating liquid for forming a high-temperature coloring layer, the coating liquid for forming an intermediate layer, and the coating liquid for forming a low-temperature coloring layer in this order, with the coating amounts after drying being 4 g/m2, 1.5 g/m2, and 3 g/m2, respectively.
The mixture was coated and dried, and subjected to super calendering to obtain a two-color thermosensitive recording material. The same intermediate layer as above was provided on a transparent polypropylene film, and the haze value was measured with a haze meter (manufactured by Tokyo Denshoku Co., Ltd., TC-HIII) and found to be 23%.

Examples 2 to 4 The coating amount of the intermediate layer forming coating solution after drying was 2.5 g/m.
Three types of two-color thermal recording bodies were obtained in the same manner as in Example 1, except that the amounts were 2, 3.5 g/m2, and 4.5 g/m2. These were designated as Examples 2, 3, and 4, and the haze values were measured in the same manner as in Example 1, and the results are listed in Table 1.

Example 5 The same procedure was carried out except that 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide was used instead of 3-diethylamino-7-chlorofluoran in the preparation of Solution C. A two-color thermosensitive recording material was obtained in the same manner as in Example 2.

Example 6 In the preparation of an intermediate layer forming coating solution, instead of kaolin,
Two colors were prepared in the same manner as in Example 3, except that 107 parts of a 30% colloidal silica aqueous solution (trade name: Snowtex-30, average particle size 10 to 20 mμ, manufactured by Nissan Chemical Co., Ltd.) and 168 parts of water were used. A colored thermosensitive recording material was obtained.

Example 7 In the preparation of an intermediate layer forming coating solution, Asahi Denka Co., Ltd. (trade name: Adelite AT-30, average particle size 10 to A two-color thermosensitive recording material was obtained in the same manner as in Example 6, except that silicone-modified polyvinyl alcohol (trade name: PVA R2105, manufactured by Kuraray Co., Ltd.) was used instead of acetoacetylated polyvinyl alcohol. .

Example 8 In the preparation of Solution C, 1-(2-methylphenoxy)- was used instead of 1,2-di(3-methylphenoxy)ethane.
A two-color thermosensitive recording material was obtained in the same manner as in Example 2 except that 2-(4-methoxyphenoxy)ethane was used.

Example 9 Two colors were prepared in the same manner as in Example 8, except that 4-hydroxyphenyl-4'-isopropyloxyphenyl sulfone was used instead of 4,4'-isopropylidene diphenol in the preparation of liquid B. A colored thermosensitive recording material was obtained.

Example 10 In preparing liquid C, 1-(2-methylphenoxy)-2
A two-color thermosensitive recording material was obtained in the same manner as in Example 9 except that oxalic acid dibenzyl ester was used instead of -(4-methoxyphenoxy)ethane.

Comparative Example 1 In the preparation of an intermediate layer forming coating solution, instead of kaolin,
A two-color thermosensitive recording material was obtained in the same manner as in Example 2, except that a silicon oxide pigment (trade name: Mizukasil P-527, average particle diameter 1.8 μm, manufactured by Mizusawa Chemical Co., Ltd.) was used.

Comparative Example 2 The coating amount of the intermediate layer forming coating liquid after drying was 7.0 g/m2.
A two-color thermosensitive recording material was obtained in the same manner as in Example 1 except for the following.

Comparative Example 3 Comparative Example 2 was prepared in the same manner as in Example 1 except that no intermediate layer was formed.
A color-developing thermosensitive recording material was obtained.

The dynamic coloring characteristics of the 13 types of two-color thermosensitive recording materials 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/mm, heating resistance: approximately 1300 ohms/dot, main scanning recording speed: 20
msec/line, sub-scan: 32 line/mm,
Recording was performed under the following conditions: head input: 0.44 W/dot, low temperature coloring energy: 0.21 mJ, high temperature coloring energy: 1.06 mJ, and the density of the recorded portion was measured with a Macbeth densitometer (model RD914, manufactured by Macbeth). The results are listed in Table 1. The color density is measured by measuring the density of the color tones corresponding to red, blue, and black, respectively, and for black fog during low temperature heating, in the case of red (low temperature color image), the blue density is measured, and the density of blue (low temperature color image) is measured.
In the case of a low-temperature color image), the yellow density was measured. If the black fog density exceeds 0.2, the sharpness of the red or blue color of the low-temperature coloring image will be significantly impaired.

[0038]

[Table 1]

[0039]

Effects of the Invention As is clear from the results in Table 1, the multicolor thermosensitive recording materials of each example of the present invention have no color mixture fog in low-temperature colored images, and have excellent recording sensitivity in high-temperature colored images. A clear multicolor image was obtained.

Claims (3)

[Claims] 1. A multicolor thermosensitive recording material comprising at least a high-temperature coloring layer, an intermediate layer, and a low-temperature coloring layer laminated on a support, the coloring layer being a leuco coloring layer containing a leuco dye and a coloring agent. A multicolor thermosensitive recording material, characterized in that the intermediate layer contains an inorganic pigment and an adhesive as main components, and has a haze value of 65% or less. 2. The multicolor thermosensitive recording according to claim 1, wherein the inorganic pigment in the intermediate layer is kaolin or colloidal silica with an average particle size of 1 μm or less, and the coating amount of the intermediate layer is 1 to 5 g/m2 in terms of dry weight. body. 3. The multicolor thermosensitive recording material according to claim 1 or 2, wherein the low-temperature coloring layer contains a thermofusible substance having a melting point of 75 to 90°C.