JPS6317084A - Thermal recording medium - Google Patents

Abstract

PURPOSE:To enhance the storage stability of a recording image, by using at least one of compounds represented by predetermined formula as a coupler in a recording layer and containing a specific phenol compound in said recording layer. CONSTITUTION:In a thermal recording medium provided with a recording layer containing a colorless or light-colored basic dye and a coupler for allowing said basic dye to form a color at the time of heating, at least one of compounds represented by the predetermined formulae [I]4n[III] is used as the coupler and a phenol compound represented by predetermined formula [IV] is contained in the recording layer. The use ratio of the basic dye to the coupler is 1:1-50 pts.wt. and the use amount of the phenol compound is preferably about 0.05-5 pts. by wt. based on 1 part of the dye. The binder in a coating solution is used in an amount of 10-70% by wt. of the total solid therein, and the coating amount of the coating solution is 2-12 g/m<2> as a dry wt.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to a heat-sensitive recording medium, and 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, cases of use as labels are 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 heat-sensitive label becomes defective in color fading. 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, new drawbacks such as the occurrence of fogging at high temperatures have not necessarily been achieved, and therefore satisfactory results have not always been obtained.

In view of the current situation, the present inventors conducted intensive research not only on storage improvers to be included in the recording layer but also on coloring agents, and as a result, the present inventors developed a compound represented by the following general formula (mV) with a specific coloration. It has been discovered that when used in combination with an agent, the water stability and moisture resistance of recorded images are significantly improved, color capri does not occur, and excellent effects are obtained in terms of plasticizer resistance, oil resistance, etc. The present invention has now been completed.

"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. As the following general formula (T) ~ (
At least one coloring agent selected from the compounds represented by I [
] This is a heat-sensitive recording material characterized by containing a phenol compound represented by the following.

[In the formula, RI-RS represents a hydrogen atom, a halogen atom, an alkyl group of 01 to 1°, an alkoxyl group of cl-(., a benzyloxy group, an aryloxy group, or a hydroxyl group, respectively. In addition, R1 and R2 or R2 and R1 may be combined with each other to form a ring.](n) ” (
III) [In the formula, R8 to RIS each represent a hydrogen atom, a halogen atom, a C1-1° alkyl group, a Cl-1° alkoxyl group, a benzyloxy group, an aryloxy group, or a hydroxyl group.] [In the formula, R1&l R1? I RIM each represents a hydrogen atom, a Cl-S alkyl group, or a C5-11 cycloalkyl group. However, RIb+ Rl 11 R
At least one of ts represents a C3~ cycloalkyl group. R3,.

R2°, R□+ R4N+ R13 each represent a hydrogen atom or a C8-〇 alkyl group. [Function] In the present invention, examples of the basic dye contained in the recording layer include various known colorless or light-colored basic dyes. For example, 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-methylindole-3-inorifthalide, 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
Diphenylmethane dyes such as -2,4,5-trichlorophenylleucoolamine, thiazine dyes such as benzoylleucomethylene blue and p-nitrobenzoylleucomethylene blue, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-
Spiro dyes such as dinaphthopyran, 3-methyl-naphtho-(6'-methoxybenzo)spiropyran, 3-propyl-spiro-dibenzopyran, rhodamine-B anilinolactam, rhodamine (p-nitroanilino)lactam, rhodamine (0- Lactam dyes such as chloroanilino)lactam, 3-dimethylamino-7-methoxyfluoran, 3-diethylamino-6-methoxyfluoran,
3-diethylamino-7-methoxyfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6゜7-dimethylfluorane, 3-( N
-ethyl-p-toluidino)-7-methylfluorane,
3-diethylamino-7-N-acetyl-N-methylaminofluorane, 3-diethylamino-7-N-methylaminofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethyl 7mi/-7 -N-methyl-N-benzylaminofluorane, 3-diethylamino-7-N-chloroethyl-N-methylaminofluorane, 3-diethylamino-7-N-diethylaminofluorane, 3-(N-ethyl-p- ) Luigino) -6-
Methyl-7-phenylaminofluoran, 3-(N-ethyl-p-)luidino)-6-methyl-7-(p-toluidino)fluoran, 3-diethylamino-6-methyl-7-phenylaminofluoran, 3-diethylamino-7-(2-carbomethoxy-phenylamino)fluorane, 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-(0-chlorophenylamino)fluoran, 3-
Pyrrolidino-6-methyl-7-P-butylphenylaminofluorane, 3-diethylamino-7-(O-fluorophenylamino)fluorane, 3-dibutylamino-
7-(o-fluorophenylamino)fluorane, 3-
(N-methyl-Nn-amyl)amino-6-methyl-
7-phenylaminofluorane, 3-(N-ethyl-N
-n-amyl)amino-6-methyl-7-phenylaminofluorane, 3-(N-ethyl-N-1so-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.

In the heat-sensitive recording material of the present invention, as described above, as a coloring agent that develops color upon contact with such a dye, a 4-hydroxydiphenylsulfone coloring agent represented by the general formula (1), a 4-hydroxydiphenylsulfone coloring agent represented by the general formula (1), and a coloring agent of the general formula (1) are used. At least one coloring agent selected from 4-hydroxybenzenesulfonylnaphthalene coloring agents represented by II) or (III) is used.

Specific examples of the coloring agent represented by general formula CI) include 4,4'-dihydroxydiphenylsulfone, 3.3
'-Dibrovanyl-4,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-chlorodiphenylsulfone, 4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxy-4'-isopropyloxydiphenylsulfone, 4- 4-hydroxydiphenylsulfone derivatives such as hydroxy-41-butoxydiphenylsulfone and 3',4'-1-dimethylene-4-hydroxydiphenylsulfone, 3'+4'-trimethylene-2
, 6-dimethyl-4-hydroxydiphenylsulfone,
3',4'-tetramethylene-4-hydroxydiphenylsulfone, 3'.

Examples include 4-hydroxydiphenylsulfone derivatives having rings at the 3' and 4' positions, such as 4'-tetramethylene-2-methyl-4-hydroxydiphenylsulfone.

Further, as specific examples of the coloring agent represented by general formula (n) or (III), for example, 1-(4-hydroxybenzenesulfonyl)naphthalene, 1-(4-hydroxybenzenesulfonyl)-4-methylnaphthalene , 1-(4-
hydroxybenzenesulfonyl)-4-methoxybenzyl, 1-(4-hydroxybenzenesulfonyl)-4-
Examples include chloronaphthalene, 1-(4-hydroxy-2-methylbenzenesulfonyl)naphthalene, and 2-(4-hydroxybenzenesulfonyl)naphthalene.

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, 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-ter
t-octylcatechol, 2,2'-dihydroxydiphenyl, 4. 4'-isopropylidene bis(2-
tert-butylphenol), 41 4'-5ec-
Butylidene diphenol, 4-phenylphenol, 4
．． 4'-isopropylidene diphenol, 2゜2'-methylenebis(4-chlorophenol), hydroquinone, 4,4'-cyclohexylidene diphenol, 4.4
'-dihydroxydiphenyl sulfide, hydroquinone monobenzyl ether, 4-hydroxybenzophenone, 2.4-dihydroxybenzophenone, 2,4.4
'-Trihydroxybenzophenone, 2.2', 4.4
'-Tetrahydroxybenzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, 4
-ethyl hydroxybenzoate, propyl 4-hydroxybenzoate, 5ec-butyl 4-hydroxybenzoate,
Pentyl 4-hydroxybenzoate, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, 4-
Tolyl hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, phenylpropyl 4-hydroxybenzoate, phenethyl 4-hydroxybenzoate, p-chlorobenzyl 4-hydroxybenzoate, p-methoxybenzyl 4-hydroxybenzoate, novolak Phenolic compounds such as type phenolic resins and phenol polymers, 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, 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-methylbenzyl salicylic 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.

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, preferably 2 to 50 parts
10 parts by weight room colorant is used.

Therefore, in the heat-sensitive recording material of the present invention, the specific phenol compound represented by the general formula [IV] is contained in the recording layer in combination with the specific coloring agent as described above. Specific examples of the phenol compound represented by the general formula [IV] include 1.1.3-tris(2-methyl-4-hydroxy-5-cyclohexyl)butane,
1.1.3-tris(2-ethyl-4-hydroxy-5
-cyclohexyl)butane, 1,1.3-)lis(2-
Methyl-4-hydroxy-5-cyclohexyl)propane, 1,1.3-)lis(2-methyl-4-hydroxy-5-cyclopentyl)butane, 1°1.3-)lis(
Examples include 2-ethyl-4-hydroxy-5-cyclopentyl)butane and 1,1.3-tris(2-methyl-4-hydroxy-5-cyclopentyl)propane.

The amount of the phenol compound represented by the general formula [IV] to be used is adjusted as appropriate depending on the type of phenol compound, basic dye, coloring agent, etc. used, but generally it is used per 1 part by weight of the dye. It is desirable to use about 0.05 to 5 parts by weight.

Coating liquids containing these substances are generally prepared using water as a dispersion medium. The phenol compound represented by the general formula [IV] may be added to the coating liquid as an aqueous dispersion, or may be added and dispersed in the process of dispersing the dye or coloring agent.

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, etc. as binders. Maleic anhydride copolymer salt, ethylene/acrylic acid copolymer salt, styrene/acrylic acid copolymer salt, styrene/butadiene copolymer emulbutane,
Urea resin, melamine resin, amide resin, etc. account for 1% of the total solid content.
It is used in an amount of about 0 to 70% by weight, preferably about 15 to 50% by weight.

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 antifoaming agents, fluorescent dyes, coloring dyes, etc. may be added as appropriate.

In addition, waxes such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, halaffin wax, and ester wax, kaolin, clay, talc, calcium carbonate, calcined gel, etc.
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, valmitic acid amide, fatty acid amides such as coconut fatty acid amide, 2,2'-methylenebis(4-methyl-6tert-
butylphenol), 4,4'-butylidene bis(6-
tert-butyl-3-methylphenol), 1,1.
3-) Lis(2-methyl-4-hydroxy-5-ter
t-butylphenyl)butane, 2,2'-methylenebis(4-ethyl-5-tert-butylphenol), 2
．． Hindered phenols such as 4-di-tert-butyl-3-methylphenol, 4.4'nithiobis(3-methyl-6-tert-butylphenol), 2-(
UV absorbers such as 2'-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, dibutyl isophthalate, 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. Furthermore, the amount of coating liquid applied is not particularly limited, and is usually 2 to 12 glrd in terms of dry weight, preferably 3 to 10 g/r.
It is prepared in a range of about rr.

Since the heat-sensitive recording material of the present invention contains a combination of the above-mentioned specific coloring agent and a phenol compound in the recording layer, it has excellent recorded image preservation properties such as water resistance, moisture resistance, plasticizer resistance, and oil resistance. However, in order to further enhance these characteristics, an overcoat layer mainly composed of a water-soluble polymer compound or the like may be provided on the recording layer.

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 resin, and colloidal silica, and organic pigments such as styrene microballs, 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 preferable to adjust the amount between about 500 parts by weight.

Furthermore, if necessary, lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, and ester Fuchs, and surfactants such as sodium dioctyl sulfosuccinate are added to the coating liquid, which is mainly composed of water-soluble polymer compounds. 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 if the dry weight exceeds 20 glrd, the recording sensitivity of the heat-sensitive recording medium may decrease significantly, so it is generally 0.1 to 20 glrd, preferably 0.5 to 10 g.
It is desirable to adjust within a range of /A.

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.

Note that "parts" and "%" in the examples indicate "parts by weight" and "% by weight", respectively, unless otherwise specified.

Example 1 ■ Preparation of liquid A 3-(N-cyclohexyl-N-methylamino)-6-
Methyl-7-phenylaminofluorane 10 parts Methyl cellulose 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.

■ Preparation of B solution 4-hydroxy-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 1.1.3-) Lis(2-methyl-4-hydroxy-5
-cyclohexyl)butane 10 parts Methyl cellulose 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. 50g/rrr 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/rrf.

Example 2 In the preparation of Solution B, 3',4'-trimethylene- was used instead of 4-hydroxy-4'-methyldiphenylsulfone.
A thermosensitive recording material was obtained in the same manner as in Example 1 except that 4-hydroxydiphenylsulfone was used.

Example 3 A thermosensitive recording material was obtained in the same manner as in Example 1, except that 2-(4-hydroxybenzenesulfonyl)naphthalene was used instead of 4-hydroxy-4'-methyldiphenylsulfone in preparing liquid B. .

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 in place of 4-hydroxy-4'-methyldiphenylsulfone in preparing liquid B.

The following evaluation tests were conducted on the seven types of heat-sensitive recording bodies thus obtained, 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 meter.

[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]

Wrap vinyl chloride lamp film (manufactured by Mitsui Toatsu Co., Ltd.) three times around a polypropylene pipe (401φ 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 wrap the film on top of that. A vinyl chloride wrap film was wrapped three times, and the plasticizer resistance was evaluated from the print density after being left at room temperature for 12 hours.

[Water resistance to plasticizers]

The colored heat-sensitive recording material was lightly wetted with water and then evaluated in the same manner as the plasticizer resistance described above to determine its water resistance to plasticizers.

〔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
A coating solution obtained by mixing and stirring ioo parts of a 10% aqueous solution of 0.0 (manufactured by Kuraray Co., Ltd.), 20 parts of calcium carbonate, and 50 parts of water was applied onto the recording layer of the above heat-sensitive recording material so that the coating amount after drying was 6 g/r+. ?
The mixture was coated and dried to obtain a heat-sensitive recording material having an overcoat layer.

Comparative example 5 ■ 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 6 ■ Formation of recording layer A thermosensitive recording material was obtained in the same manner as in Comparative Example 4.

(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 thus obtained were subjected to the same evaluation tests as described above, except that the plasticizer resistance and water plasticizer resistance were evaluated using the following methods, 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 fl φ pipe), sandwich a heat-sensitive recording material with colored print on top of it so that the colored side of the print is facing out, and then wrap it on top of that. The plasticizer resistance was evaluated from the print density after wrapping three layers of vinyl chloride wrap film and leaving it at 40° C. for 24 hours.

[Water resistance to plasticizers]

The colored heat-sensitive recording material was wetted with light water and then evaluated in the same manner as the plasticizer resistance described above to determine its water plasticizer resistance.

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 a remarkable improvement in oil resistance, etc., and no color fog was observed.

Patent Applicant: Kanzaki Paper Co., Ltd. Procedure Kugi 1↑Shoshi September 2, 1988 Patent Application No. 162607, 1988 2, Title of Invention Thermal Recording Material 3, Relationship with the Person Making Amendment Case Patent Applicant 4, Agent's residence: Kanzaki Seigi Co., Ltd., 4-3-1 Jokoji, Amagasaki City, 660 JPY (Contents of amendment) The specification of application B is amended as follows.

(11 Specification, page 15, line 18 to page 16, line 8, "ba1,1.3-tris...propane etc. can be mentioned.") was changed to "ba1,1.3- Tris(2-methyl-4
-hydroxy-5-cyclohexylphenyl)butane,
1.1.3-)IJs(2-ethyl-4-hydroxy-
5-cyclohexylphenyl)butane, 1,1.3-1
-Lis(2-methyl-4-hydroxy-5-cyclohexylphenyl)propane, 1,1.3-tris(2-methyl-4-hydroxy-5-cyclopentylphenyl)
Butane, 1,1.3-tris(2-ethyl-4-hydroxy-5-cyclopentylphenyl)butane, 1,1.
3-) Lis(2-methyl-4-hydroxy-5-cyclopentylphenyl)propane and the like. ” he corrected.

(2) "Cyclohexyl" on page 24, line 14 of the specification
Insert "phenyl" after.

−1 above

Claims (1)

[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 represented by the following general formulas [I] to [
A thermosensitive recording material characterized by using at least one coloring agent selected from the compounds represented by [III], and containing a phenol compound represented by the following general formula [IV] in the recording layer. . ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [I] [In the formula, R_1 to R_5 are hydrogen atoms, halogen atoms, alkyl groups of C_1_ to _1_0, and C_1_ to _
1_0 represents an alkoxyl group, benzyloxy group, aryloxy group, or hydroxyl group. In addition, R_1 and R_
2 or R_2 and R_3 may be combined with each other to form a ring. ] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [II] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [III] [In the formula, R_6 to R_1_5 are hydrogen atoms, halogen atoms, alkyl groups of C_1_ to _1_0, C_1_
~_1_0 represents an alkoxyl group, benzyloxy group, aryloxy group, or hydroxyl group. ] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [IV] [In the formula, R_1_6, R_1_7, and R_1_8 are each a hydrogen atom, an alkyl group of C_1_ to_8, or C_5_
~_8 cycloalkyl group is shown. However, R_1_6, R
At least one of _1_7 and R_1_8 is C_5_~_
8 shows a cycloalkyl group. R_1_9, R_2_0
, R_2_1, R_2_2, and R_2_3 each represent a hydrogen atom or an alkyl group of C_1_ to_8. ]