JPS63111088A - Thermal recording material - Google Patents

Abstract

PURPOSE:To enhance water resistance, plasticizer resistance and oil resistance, by incorporating a specified compound and at least one specified phenol compound as a color reaction agent for developing the color of a basic dye when being heated. CONSTITUTION:A recording layer comprising a colorless or light-colored basic dye and a color reaction agent for developing the color of the dye when being heated is provided, a compound of formula [I] and at least one phenol compound of formula [II] being incorporated as the color reaction agent. In formula [I], X is hydrogen, a halogen, alkyl or alkoxyl, and each of R1-R5 is hydrogen, a halogen, hydroxyl, alkyl, cycloalkyl, aralkyl, aryl, alkoxyl, aralkyloxyl, aryloxyl, alkylthio, aralkylthio or arylthio. In formula [II], each of R6-R9 is hydrogen or a 1-8C alkyl.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to a heat-sensitive recording medium, and more particularly to a heat-sensitive recording medium with excellent storage stability of recorded images.

``Prior art'' Thermal recording materials that utilize a color reaction between a colorless or light-colored basic dye and an organic or inorganic coloring agent to obtain a recorded image by bringing a recoloring substance into contact with heat are well known. Are known.

Such heat-sensitive recording media are relatively inexpensive, and the recording devices are compact and relatively easy to maintain, so they are used not only as recording media for facsimiles and various computers, but also in a wide range of fields.

For example, one of the fields of use is POS at retail stores, etc.
' (Point of 5ales) With the expansion of systemization, the number of cases in which labels are used as labels is increasing.

However, when a POS system is introduced in a supermarket or the like, the labels often come into contact with water, plastic wrap, and oil, and as a result, the recorded image (print) on the label fades due to the effects.

Therefore, thermal recording materials are required to have qualities such as water resistance, plasticizer resistance, and oil resistance.

``Problems to be Solved by the Invention'' In order to improve the storage stability of recorded images, methods of adding various storage improvers have been proposed, but with the improvement, the whiteness of the recording layer decreases. However, satisfactory results have not always been obtained due to new drawbacks such as the generation of capri at high temperatures.

In view of the current situation, the inventors of the present invention have conducted intensive research on the coloring agent to be contained in the recording layer, and as a result, the following general formula (1
) and (If) in combination, the water stability and moisture resistance of recorded images are significantly improved, color fog does not occur, and plasticizer resistance and oil resistance are improved. The present inventors have discovered that excellent effects can also be obtained in the above methods, and have completed the present invention.

"Means for Solving the Problem" The present invention provides a heat-sensitive recording material provided with a recording layer containing a colorless or light-colored basic dye and a coloring agent that causes the basic dye to develop color when heated. This is a heat-sensitive recording material characterized by containing at least one of a compound represented by the following general formula [I] and a phenol compound represented by the following general formula (If).

[In the formula, X represents a hydrogen atom, a halogen atom, an alkyl group, or an alkoxyl group, and R3 to R1 each represent a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group, a cycloalkyl group, an aralkyl group, or group, alkoxyl group, aralkyloxy group, aryloxy group, alkylthio group, aralkylthio group, or arylthio group, where R, and R, , R, and R1 represent a naphthalene ring or tetrahydronaphthalene together with an adjacent benzene ring. A ring or an indane ring may be formed. ] [In the formula, R6 to R9 each represent a hydrogen atom or a C3 to C8 alkyl group.] "Function" In the present invention, as the basic dye contained in the recording layer, various known colorless dyes are used. Basic dyes include 0 such as 3,3-bis(p-dimethylaminophenyl)
-6-dimethylaminophthalide, 3.3-bis(p-dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl)-3-(1,2-dimethylindol-3-yl)phthalide, 3- (p-dimethylaminophenyl)-3-(2-methylindol-3-yl)phthalide, 3,3-bis(1,2-dimethylindole-3)
-yl)-5-dimethylaminophthalide, 3.3-bis(1,2-dimethylindol-3-yl)-6-dimethylaminophthalide, 3゜3-bis(9-ethylcarbazol-3-yl) )-6-dimethylaminophthalide, 3
．． 3-bis(2-phenylindol-3-yl)-6
-dimethylaminophthalide, 3-p-dimethylaminophenyl-3-(1-methylpyrrol-3-yl)-6-
triallylmethane dyes such as dimethylaminophthalide,
4.4'-bis-dimethylaminobenzhydrylbenzyl ether, N-halophenyl-leucoolamine, N
-2,4,5-) Diphenylmethane dyes such as dichlorophenyl leuco auramine, thiazine dyes such as benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran , 3-phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho-(6'-methoxybenzo)spiropyran, 3-propyl-spiro-dibenzopyran, and other spiro dyes, rhodamine -B Lactam dyes such as anilinolactam, rhodamine (p-nitroanilino) lactam, rhodamine (0-chloroanilino) lactam, 3-dimethylamino-7-methoxyfluoran, 3-diethylamino-6-methoxyfluoran, 3- Diethylamino-7-methoxyfluorane, 3-
Diethylamino-7-chlorofluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3-
Diethylamino-6゜7-dimethylfluorane, 3-(
N-ethyl-p-toluidino)-7-methylfluorane, 3-diethylamino-7-N-acetyl-N-methylaminofluorane, 3-diethylamino-? -N-methylaminofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-N-
Methyl-N-benzylaminofluorane, 3-diethylamino-7-N-chloroethyl-N-methylaminofluorane, 3-diethylamino-? -N-diethylaminofluorane, 3-(N-ethyl-p-)luidino)-6
-Methyl-7-phenylaminofluorane, 3-(N-
Ethyl-p-toluidino)-6-methyl-7-(p-toluidino)fluoran, 3-diethylamino-6-methyl-7-phenylaminofluorane, 3-diethylamino-7-(2-carbomethoxy-phenylamino) Fluoran, 3-(N-cyclohexyl-N-methylamino)-6-methyl-7-phenylaminofluoran, 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-diethylamino-7-(o-fluorophenylamino)fluoran, 3-dibutylamino-7-(o-fluorophenylamino)fluoran, 3
-(N-methyl-N-n-amyl)amino-6-methyl-7-phenylaminofluorane, 3-(N-ethyl-
N-n-amyl)amino-6-methyl-7-phenylaminofluorane, 3-(N-ethyl-N-iso-amyl)amino-6-methyl-7-phenylaminofluorane, 3-(N- Methyl-N-n-hexyl)amino-6
-Methyl-7-phenylaminofluorane, 3-(N-
Ethyl-Nn-hexyl)amino-6-methyl-7-
Phenylaminofluorane, 3- (N-ethyl-N-
Examples include fluoran dyes such as β-ethylhexyl)amino-6-methyl-7-phenylaminofluoran. In addition, two or more types of these basic dyes can be used in combination as necessary.

As described above, in the heat-sensitive recording material of the present invention, a specific 3,4-dihydroxydiphenylsulfone compound represented by the general formula CI) and a general formula [ (2) A specific phenol compound represented by [2] is used.

Specific examples of the coloring agent represented by general formula (1) include 3,4-dihydroxydiphenylsulfone, 3,4-
Dihydroxy-4'-methyldiphenylsulfone, 3.
4-dihydroxy-4'-ethyldiphenylsulfone,
3.4-dihydroxy-4'-propyldiphenylsulfone, 3.4-dihydroxy-4'-isopropyldiphenylsulfone, 3.4-dihydroxy-4'-butyldiphenylsulfone, 3.4-dihydroxy-2'4'
-dimethyldiphenylsulfone, 3.4-dihydroxy-4'-chlordiphenylsulfone, 3.4.4'-)
Lihydroxydiphenylsulfone, 3.4-dihydroxy-4'-cyclohexyldiphenylsulfone, 3.4
-dihydroxy-4'-methoxydiphenyl sulfone,
3.4-dihydroxy-4'-ethoxydiphenylsulfone, 3.4-dihydroxy-4'-phenoxydiphenylsulfone, 3.4-dihydroxy-4'-benzyloxydiphenylsulfone, 3,4-dihydroxy-4
1-benzyldiphenylsulfone, 3,4-dihydroxy-4'-phenethyldiphenylsulfone, 3,4-dihydroxy-4'-methylthiodiphenylsulfone, 3
, 4-dihydroxy-4'-ethylthiodiphenylsulfone, 3゜4-dihydroxy-4'-phenylthiodiphenylsulfone, 3,4-dihydroxy-4'-benzylthiodiphenylsulfone, 3,4-dihydroxyphenyl-1- Naphthylsulfone, 3.4-dihydroxyphenyl-2-naphthylsulfone, 3.4-dihydroxy-2',3'-)rimethylenediphenylsulfone, 3.
Examples include 4-dihydroxy-2', 3'-tetramethylene diphenyl sulfone.

Moreover, as a specific example of the specific phenol compound represented by the general formula [II], for example, 1,4-di(2-(4
-hydroxyphenyl)-2-propyl]benzene, 1
,3-di(2-(4-hydroxyphenyl)-2-propyl)benzene, 1゜4-di(2-(3,5-dimethyl-4-hydroxyphenyl)-2-propyl)benzene, 1,3 -di(2-(3,5-dimethyl-4-hydroxyphenyl)-2-propyl]benzene, 1.4-di(2-(3,5-diethyl-4-hydroxyphenyl)
-2-propyl]benzene, 1,3-di(2-(3,5
-diethyl-4-hydroxyphenyl)-2-propyl]benzene, 1,4-di[2-(3,5-di-1so-
Propyl-4-hydroxyphenyl)-2-propyl]
Benzene, 1°3-di(2-(3,5-di-1so-propyl-4-hydroxyphenyl)-2-propyl)benzene, 1.4-di(2-(3,5-di-tert)
-propyl-4-hydroxyphenyl)-2-propyl]benzene, 1,3-di(2-(3,5-di-ter
Examples include t-propyl-4-hydroxyphenyl)-2-propyl]benzene.

In the present invention, the usage ratio of the basic dye and coloring agent is appropriately selected depending on the type of basic dye and coloring agent used, and is not particularly limited, but in general, 1 weight of the basic dye 1 to 50 parts by weight, preferably 2 to 50 parts by weight
10 parts by weight room colorant is used. Of these, the general formula [
The amount of the phenol compound represented by II] is determined based on the amount of the phenol compound used, the basic dye and the general formula (II).
Although the coloring agent represented by ) is adjusted as appropriate depending on the type of coloring agent, it is generally desirable to use about 0.05 to 5 parts by weight per 1 part by weight of the dye.

In addition, it is also possible to use ordinary coloring agents in addition to the above-mentioned specific coloring agents within a range that does not impede the effects of the present invention, such as activated clay, acpargite, colloidal silica, aluminum silicate, etc. inorganic acidic substances, 4 te
rt-Butylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, 4-hydroxyacetophenol, 4-tert-octylcatechol, 2,2'-dihydroxydiphenol, 4,4'-isopropylidene bis(2 -tert-butylphenol), 4+ 4' -5ec-butylidenediphenol, 4-phenylphenol, 4.4'-isopropylidenediphenol, 2.2'-methylenebis(4-chlorophenol), hydroquinone, 4.4' -Cyclohexylidene diphenol, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-methyldiphenyl sulfone, 4-hydroxy-4'-isopropyloxydiphenyl sulfone, hydroquinone monobenzyl Ether, 4-hydroxybenzophenone, 2.4-dihydroxybenzophenone, 2.4.4'-)dihydroxybenzophenone, 2.2',4.4'-tetrahydroxybenzophenone, dimethyl 4-hydroxyphthalate, 4
-Methyl hydroxybenzoate, propyl 4-hydroxybenzoate, 5ec-fufu, 4-hydroxybenzoate.

Pentyl benzoate, phenyl 4-hydroxybenzoate,
Benzyl 4-hydroxybenzoate, tolyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate,
Phenylpropyl 4-hydroxybenzoate, phenethyl 4-hydroxybenzoate, p-4-hydroxybenzoate
- Phenolic compounds such as chlorobenzyl, p-methoxybenzyl 4-hydroxybenzoate, novolac type phenolic resin, phenol polymer, benzoic acid, p-te
r t-Butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, 3-sec-butyl-4-hydroxybenzoic acid, 3-cyclohexyl-4-hydroxybenzoic acid, 3.
5-dimethyl-4-hydroxybenzoic acid, 3-tert
-butylsalicylic acid, 3-benzylsalicylic acid, 3-(
α-Methylbenzyl)salicylic acid, 3-chloro-5-(
α-methylbenzyl)salicylic acid, 3,5-diter
t-Butylsalicylic acid, 3-phenyl-5-(α, α
Aromatic carboxylic acids such as -dimethylbenzyl)salicylic acid, 3,5-di-α-methylbenzylsalicylic acid, and their phenolic compounds, aromatic carboxylic acids such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, Examples include organic acidic substances such as salts with polyvalent metals such as nickel.

Coating liquids containing these substances are generally prepared using water as a dispersion medium. Coating liquids usually contain starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein,
Gum Arabic, polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, diisobutylene/maleic anhydride copolymer salt, styrene/maleic anhydride copolymer salt, ethylene/acrylic acid copolymer salt, styrene/acrylic acid copolymer Salt, styrene-butadiene copolymer emulsion, urea resin, melamine resin, amide resin, etc. are used in an amount of about 10 to 70% by weight, preferably about 15 to 50% by weight of the total solid content.

Furthermore, various auxiliaries can be added to the coating liquid as necessary, such as sodium dioctyl sulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, fatty acid metal salts, etc. Dispersants, UV absorbers such as benzophenone,
Other foaming agents, fluorescent dyes, coloring dyes, etc. may be added as appropriate.

In addition, waxes such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, and ester wax, kaolin, clay, talc, calcium carbonate, calcined gel,
Inorganic pigments such as titanium oxide, diatomaceous earth, particulate anhydrous silica, and activated clay may also be added.

Furthermore, a sensitizer can also be used in combination depending on the purpose. Specific examples of sensitizers include stearic acid amide, stearic acid methylene bisamide, oleic acid amide, palmitic acid amide, fatty acid amides such as coconut fatty acid amide, and 2,2'-methylenebis(4-methyl-6-tert).
-butylphenol), 4,4'-butylidene bis(6
tert-butyl-3-methylphenol), 2.2'
-Hindered phenols such as methylenebis(4-ethyl-6=tert-butylphenol), 2,4-di-tert-butyl-3-methylphenol! , 2-(2'
UV absorbers such as -hydroxy-5'-methylphenyl)benzotriazole, 2-hydroxy-4-benzyloxybenzophenone, 1°2-di(3-methylphenoxy)ethane, 1,2-diphenoxyethane, 1- Phenoxy-2-(4-methylphenoxy)ethane, dimethyl terephthalate, dibutyl terephthalate, dibenzyl terephthalate, diptyle isofucric acid, phenyl 1-hydroxynaphthoic acid, various known thermofusible substances, etc. can be mentioned.

The amount of sensitizer used is not particularly limited, but generally color former 1
It is desirable to adjust the amount within a range of about 4 parts by weight or less.

In the heat-sensitive recording material of the present invention, the method for forming the recording layer is not particularly limited, and may be formed, for example, by a method of applying and drying a coating liquid by air knife coating, blade coating, or the like. Further, the amount of the coating liquid to be applied is not particularly limited, and is usually applied in a dry weight range of 2 to 12 g/m, preferably 8 times in a range of about 3 to 10 g/m.

Since the heat-sensitive recording material of the present invention contains a combination of the above-described two types of compounds as a coloring agent in the recording layer,
It exhibits excellent archival properties such as water resistance, humidity resistance, plasticizer resistance, oil resistance, etc., but in order to further improve these properties, the main component is a water-soluble polymer compound on the recording layer. An overcoat layer can also be provided.

Examples of water-soluble polymer compounds used in the overcoat layer include polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, starch and its derivatives, casein, sodium alginate, Examples include polyvinylpyrrolidone, polyacrylamide, styrene-maleic acid copolymer salt, polyurethane resin, urea resin, melamine resin, polyamide resin, epichlorohydrinated polyamide resin, and the like. Of course, two or more of these polymer compounds may be used in combination.

Note that among these water-soluble polymer compounds, acetoacetyl group-modified polyvinyl alcohol is particularly preferably used because it exhibits excellent effects when combined with the specific substance of the present invention.

Pigments can be added to the overcoat layer as necessary to improve printability and sticking. Specific examples of pigments include calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, silicon dioxide, aluminum hydroxide, barium sulfate, zinc sulfate, talc,
Examples include inorganic pigments such as kaolin, clay, calcined clay, and colloidal silica, and organic pigments such as styrene microspheres, nylon powder, polyethylene powder, urea/formalin resin filler, and raw starch granules.

The amount used is generally 5 to 100 parts by weight of the resin component.
It is desirable to adjust the amount within a range of about 500 parts by weight.

Furthermore, if necessary, lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, and ester wax, and surfactants such as sodium dioctyl sulfosuccinate may be added to coating liquids containing water-soluble polymer compounds as the main component. Various auxiliary agents such as agents (dispersants, lubricants) and antifoaming agents can also be added as appropriate.

In addition, to further improve water resistance, glyoxal,
Hardening agents such as boric acid, dialdehyde starch, and epoxy compounds can also be added.

In the present invention, the coating liquid forming the overcoat layer is
Generally, it is prepared as an aqueous coating liquid, and if necessary, it can be mixed and processed using a mixer, attritor, ball mill, roll mill, etc.
After thorough mixing and dispersion using a stirrer, the mixture is coated onto the heat-sensitive recording layer using a suitable coating device. The amount of coating is not particularly limited, but the dry weight is 20 g/n? If the temperature exceeds 0.1 to 20 g/m, preferably 0.5 to 10 g/r, the recording sensitivity of the heat-sensitive recording medium may decrease significantly.
It is desirable to adjust within a range of about rr.

Thus, the heat-sensitive recording material of the present invention having an overcoat layer provided on the recording layer does not cause color fog and exhibits extremely excellent recorded image retention even under severe conditions.

Note that, if necessary, it is also possible to further improve the storage stability by providing a protective layer on the back side of the heat-sensitive recording material. Furthermore, various known techniques in the field of heat-sensitive recording material production may be added as necessary, such as providing an undercoat layer on the support, applying an adhesive treatment to the back surface of the recording material, and processing it into an adhesive label.

As the support, paper, plastic film, synthetic paper, etc. can be used, but paper is most preferably used in terms of cost, coatability, etc.

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

In addition, "part" and "%" in the layer are 1 unless otherwise specified.
"Parts by weight" and "% by weight" are shown, respectively.

Example 1 ■ Preparation of Solution A 3-Dibutylamino-7-(0-chlorophenylamino)fluoran 10 parts Methylcellulose 5% aqueous solution 5 parts Water
40 parts of this composition was ground in a sand mill until the average particle size was 3 μm.

■ Bl preparation 3.4-dihydroxy-4'-methyldiphenylsulfone 20 parts methylcellulose
5% aqueous solution 5 parts water
55 parts of this composition was ground in a sand mill until the average particle size was 3 μm.

■ Preparation of liquid C 1.3-di(2-(4-hydroxyphenyl)-2-propyl)benzene 10 parts Methylcellulose 5% aqueous solution 5 parts water
40 parts of this composition was ground in a sand mill until the average particle size was 3 μm.

(2) Formation of Recording Layer 55 parts of liquid A, 80 parts of liquid B, 55 parts of liquid C, 50 parts of a 15% aqueous polyvinyl alcohol solution, and 10 parts of calcium carbonate were mixed and stirred to prepare a coating liquid. 50 g/rd of the obtained coating liquid
A heat-sensitive recording material was obtained by coating and drying the mixture on a base paper so that the coating amount after drying was 6 g/rd.

Example 2 Thermal recording was carried out in the same manner as in Example 1, except that 3,4-dihydroxy-4'-ethyldiphenylsulfone was used instead of 3,4-dihydroxy-4'-methyldiphenylsulfone in preparing liquid B. I got a body.

Example 3 In the preparation of liquid C, 1.4-di(2-(4-hydroxyphenyl)-2-propyl)benzene was replaced with
A thermosensitive recording material was obtained in the same manner as in Example 1 except that -di(2-(4-hydroxyphenyl)-2-propyl)benzene was used.

Comparative Examples 1 to 3 Thermosensitive recording bodies were obtained in the same manner as Examples 1 to 3, except that liquid C was not used in forming the recording layer.

Comparative Example 4 A thermosensitive recording material was obtained in the same manner as in Example 1, except that 4,4'-isopropylidene diphenol was used instead of 3,4-dihydroxy-4'-methyldiphenylsulfone in preparing liquid B. Ta.

Comparative Example 5 In preparing liquid B, 4-hydroxy-4' was used instead of 3,4-dihydroxy-4'-methyldiphenylsulfone.
- Example 1 except that methyldiphenyl sulfone was used
A thermosensitive recording material was obtained in the same manner as above.

The following evaluation tests were conducted on the eight types of heat-sensitive recording bodies obtained in this manner, and the results are listed in Table 1.

[Whiteness]

In order to evaluate the degree of color fog, the whiteness of the recording layer was measured using a Hunter whiteness needle.

[Color density]

The color density of the recorded image obtained by printing with a thermal printer was measured with a Macbeth densitometer (manufactured by Macbeth, Model RD-100R).

〔water resistance〕

After printing, the heat-sensitive recording material was immersed in water and left at room temperature for 48 hours, after which the water resistance was evaluated from the print density.

[Plasticizer resistance] Vinyl chloride lamp film (manufactured by Mitsui Raisatsu Co., Ltd.) is wrapped three times around a polypropylene pipe (40 fin diameter tube), and a heat-sensitive recording material with colored prints is placed on top of it, with the printed colored side facing outward. Then, a vinyl chloride wrap film was wrapped three times over it, and the plasticizer resistance was evaluated from the print density after leaving it at room temperature for 12 hours.

〔Oil resistance〕

After printing, several drops of cottonseed oil were dropped onto the printed colored area of the heat-sensitive recording material, and after 24 hours, it was wiped off with gauze, and the oil resistance was evaluated from the print density.

Example 4 ■ Formation of recording layer A thermosensitive recording material was obtained in the same manner as in Example 1.

■ Formation of overcoat layer Polyvinyl alcohol (Product name: PVA-11
0, manufactured by Kuraray Co., Ltd.), 20 parts of calcium carbonate, and 50 parts of water were mixed and stirred, and a coating solution obtained was applied onto the recording layer of the above heat-sensitive recording material so that the coating amount after drying was 6 g/rrf.
The mixture was coated and dried to obtain a heat-sensitive recording material having an overcoat layer.

Comparative example 6 ■ Formation of recording layer A thermosensitive recording material was obtained in the same manner as in Comparative Example 1.

(2) Formation of overcoat layer A thermosensitive recording material having an overcoat layer was obtained in the same manner as in Example 4 except that the above thermosensitive recording material was used.

Comparative example 7 ■ Formation of recording layer A thermosensitive recording material was obtained in the same manner as in Comparative Example 5.

(2) Formation of overcoat layer A thermosensitive recording material having an overcoat layer was obtained in the same manner as in Example 4 except that the above thermosensitive recording material was used.

The three types of heat-sensitive recording materials obtained in this manner were subjected to the same evaluation test as described above, except that the plasticizer resistance was evaluated by the following method, and the results are listed in Table 2.

[Plasticizer resistance]

Wrap vinyl chloride wrap film (manufactured by Mitsui Toatsu Co., Ltd.) three times around a polypropylene pipe (40 Tsuru φ pipe), sandwich the heat-sensitive recording material with colored print on it so that the colored side of the print is on the outside, and then A vinyl chloride wrap film was wrapped three times over it, and the plasticizer resistance was evaluated from the print density after being left at 40° C. for 24 hours.

Table 1 Table 2 "Effects" As is clear from the results in Tables 1 and 2, the heat-sensitive recording material of the present invention has excellent storage stability of recorded images, especially water resistance and plasticizer resistance. It was an excellent recording medium with remarkable improvement in oil resistance, etc., and no color capri.

Patent applicant: Kanzaki Paper Co., Ltd. Procedural amendment July 2, 1986

Claims (2)

[Claims] (1) In a heat-sensitive recording material provided with a recording layer containing a colorless or light-colored basic dye and a coloring agent that causes the basic dye to develop color when heated, the coloring agent is expressed by the following general formula [I]. 1. A heat-sensitive recording material containing at least one of a compound represented by the following general formula [II] and a phenol compound represented by the following general formula [II]. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [I] [In the formula, ,
It represents a cycloalkyl group, an aralkyl group, an aryl group, an alkoxyl group, an aralkyloxy group, an aryloxy group, an alkylthio group, an aralkylthio group, or an arylthio group. Note that R_1 and R_2, R_2 and R_3 may form a naphthalene ring, a tetrahydronaphthalene ring, or an indane ring together with mutually adjacent benzene rings. ] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [II] [In the formula, R_6 to R_9 are each a hydrogen atom or C_1
Indicates an alkyl group from ___ to ___8. ] (2) The heat-sensitive recording material according to claim (1), which has an overcoat layer above the recording layer.