JP2003063149A - Heat sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a characteristically well-balanced heat sensitive recording material, which is excellent in the whiteness and heat responsiveness of a ground, and excellent in resistance to plasticizer, resistance to moist heat, heat resistance, light resistance or the like of a recorded image and the storage stability of a ground part. SOLUTION: In the heat sensitive recording material, a heat sensitive color developing layer contains a condensation reaction product between a carboxylic acid component (A) having an essential component of (poly)4-hydroxybenzoic acid represented by general formula (1) (wherein, p represents an integer of 0 to 2) and a polyhydric alcoholic component (B) including a trihydric or more polyhydric alcohol as an essential component as an organic acidic substance and, in addition, a 4-acetyl biphenyl is also included in the layer as a sensitizer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material, which is excellent in whiteness and heat response of the background and has a recorded image such as plasticizer resistance, moisture heat resistance, heat resistance and light resistance, and storage stability of the background portion. The present invention relates to a heat-sensitive recording material having excellent properties and good performance balance.

[0002]

2. Description of the Related Art A thermosensitive recording material comprising a support and a thermosensitive coloring layer containing a colorless or light-colored leuco dye at room temperature and an organic acidic substance which reacts with the leuco dye to produce a color when heated is a printing device. Has many advantages such as being relatively easy and compact, and requiring no maintenance such as consumables such as ink and ribbons, computer output, printers such as calculators, recorders for various measuring instruments, facsimiles. It is used in many fields, such as automatic ticket issuing machines, thermal copying machines, and labels.

As the use of the heat-sensitive recording material expands, the recorded image of the whiteness of the background, the plasticizer resistance, the heat and moisture resistance, the heat resistance, the light resistance, etc., and the storage stability of the background portion are maintained while maintaining the color development sensitivity. The demand for sex is becoming stricter. In order to improve the stability of these recorded images and the background, many proposals of new leuco dyes, organic acidic substances or sensitizers have been made, but while maintaining the color development sensitivity, there are sufficient demands for various storability. It is difficult to be satisfied.

As organic acidic substances which have been conventionally used in general, 2,2-bis (4-hydroxyphenyl) propane, benzyl p-hydroxybenzoate described in JP-A-56-144193, JP-A-60-13852. 4-hydroxy-4'-isopropoxydiphenyl sulfone described in Japanese Patent Application Publication No. 2004-242242 is mentioned. Although these are excellent in color development sensitivity, they are not satisfactory in terms of storability of recorded images.

On the other hand, for the purpose of improving the storage stability of the background and color images, WO99 / 51444 proposes to use a high molecular weight hydroxybenzoic acid ester as an organic acidic substance. This high molecular weight hydroxybenzoic acid ester is excellent in storage stability of recorded images, but the sensitizer taught in the publication is not sufficiently satisfactory from the viewpoint of storage stability of the background and color development sensitivity.

[Problems to be Solved by the Invention]

The present invention was devised in view of such a viewpoint, and the object thereof is to obtain excellent whiteness of the background and heat response, plasticizer resistance, moist heat resistance, heat resistance, light resistance, etc. Another object of the present invention is to provide a heat-sensitive recording material which is excellent in the storage stability of the recorded image and the background portion and has a good performance balance. The other purpose is
Another object of the present invention is to provide a heat-sensitive recording material in which the effect of the organic acidic substance disclosed in WO99 / 51444 is further enhanced.

[Means for Solving the Problems]

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that as an organic acidic substance, WO99 / 5144.
The organic acid substance disclosed in Japanese Patent No. 4 is used as a sensitizer.
-By containing acetylbiphenyl, it provides a heat-sensitive recording material with excellent performance balance, which has excellent recorded images such as whiteness of the background, plasticizer resistance, heat and humidity resistance, heat resistance and light resistance, and storage stability of the background. The inventors have found that they can be achieved and have completed the present invention.

That is, the present invention provides a heat-sensitive recording material comprising a support and a thermosensitive coloring layer containing a colorless or pale-colored leuco dye at room temperature and an organic acidic substance which reacts with the leuco dye to develop a color. In, a carboxylic acid component (A) containing (poly) 4-hydroxybenzoic acid represented by the general formula (1) as an essential component as an organic acidic substance
And a polyhydric alcohol component (B) containing a trihydric or higher polyhydric alcohol as an essential component,
Further, the heat-sensitive recording material is characterized by containing 4-acetylbiphenyl as a sensitizer.

[Chemical 3] (However, p represents an integer of 0 to 2) Here, as the trihydric or higher polyhydric alcohol, a compound represented by the following general formula (2) is mentioned as one of the preferable ones.

[Chemical 4] (However, n represents an integer of 0 to 9, and R ₁ and n R ₂ are each independently a hydroxymethyl group or a carbon number of 1 to 8.
Represents the alkyl group of

The present invention will be described in detail below. In the present invention, the leuco dye used as a color former is a substance which is colorless or light-colored at room temperature and develops a color by reacting with an organic acidic substance when heated. Examples of such leuco dyes include 3- (N, N-diethylamino) -6-methyl-
7-anilinofluorane, 3- (N, N-dibutylamino) -6-methyl-7-anilinofluorane, 3- (N
-Ethyl-N- (i-butyl) amino) -6-methyl-
7-anilinofluorane, 3- (N, N-dipentylamino) -6-methyl-7-anilinofluorane, 3-
(N, N-dibutylamino) -7- (o-chloroanilino) fluorane, 3- (N, N-dibutylamino) -6
-Methyl-7- (o-chloroanilino) fluorane, 3
Fluorane dyes such as-(N-ethyl-N- (p-tolyl) amino) -6-methyl-7-anilinofluorane and 3,3-bis (p-dimethylaminophenyl) -6.
-Dimethylaminophthalide, 3- (p-dimethylaminophenyl) -3- (2-phenyl-3-indolyl) phthalide, 3- (p-dimethylaminophenyl) -3-
(1,2-Dimethyl-3-indolyl) phthalide, 3,
3-bis (9-ethyl-3-carbazolyl) -5-dimethylaminophthalide, 3,3-bis (2-phenyl-3)
-Indolyl) -5-dimethylaminophthalide and other triallylmethane dyes, for example, 4,4'-bisdimethylaminobenzhydridobenzyl ether and other diphenylmethane dyes, for example, benzoyl leuco methylene blue and other thiazine dyes Further, for example, spiro dyes such as 3-methylspirodinaphthopyran and other dyes such as leuco auramine dyes, indoline dyes, indigo dyes, and the like. These leuco dyes may be used either individually or in combination of two or more.

The organic acidic substance used in the present invention is
A carboxylic acid component (A) containing (poly) 4-hydroxybenzoic acid represented by the general formula (1) as an essential component, and a polyhydric alcohol component (B) containing a polyhydric alcohol of trihydric or higher as an essential component Condensation reaction product of (hereinafter, (poly) 4
-Hydroxybenzoic acid ester derivative). Here, the carboxylic acid component (A), the polyhydric alcohol component (B), and the (poly) 4-hydroxybenzoic acid ester derivative derived therefrom are the compounds described in WO99 / 51444.
The carboxylic acid component (A), the polyhydric alcohol component (B), and the (poly) 4-hydroxybenzoic acid ester derivative described in JP-A No. 2003-242242 can be used. Hereinafter, this will be described in detail.

The carboxylic acid component (A) contains (poly) 4-hydroxybenzoic acid represented by the general formula (1) as an essential component. Although other monovalent carboxylic acid or divalent carboxylic acid may be contained as an optional component, the carboxylic acid component (A)
50 mol% or less of all carboxyl groups in the medium, preferably 2
It is better to keep it to 0 mol% or less. However, in order to improve performance, it is advantageous to include these in small amounts. Further, in the general formula (1), p represents 0, 1 or 2, but is preferably 0 or 1.

The polyhydric alcohol component (B) contains a trihydric or higher polyhydric alcohol as an essential component. If necessary, a dihydric low molecular weight alcohol may be contained, but it is preferably 50 mol% or less, preferably 20 mol% or less, of all alcoholic hydroxyl groups in the polyhydric alcohol component (B). Trivalent or higher polyhydric alcohol is necessary for obtaining a heat-sensitive recording material having excellent color development sensitivity and storage stability, and this effect cannot be expected only with divalent low-molecular alcohol. Examples of trihydric or higher polyhydric alcohols include hexitols, pentitols, pentaerythritol, trimethylolethane,
Trimethylol propane, tetramethylol propane,
Examples thereof include glycerin, a condensate of these trihydric or higher polyhydric alcohols, and a condensate of a trihydric or higher polyhydric alcohol and a dihydric low-molecular-weight alcohol, and in particular, the polyhydric alcohol represented by the above general formula (2). Are preferred.
In the general formula (2), n represents an integer of 0 to 9 and R ₁
And n R ₂ each independently represent a hydroxymethyl group or an alkyl group having 1 to 8 carbon atoms, preferably,
n is 1 to 3 and R ₁ and R ₂ are hydroxymethyl groups. Pentaerythritol, trimethylolpropane or a condensate thereof is more preferred.
When the dihydric low molecular weight alcohol is used in combination with the polyhydric alcohol, examples of the dihydric low molecular weight alcohol include ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol and 3-methyl-1. , 5-pentanediol, 1,6-
Examples include glycols such as hexanediol and cyclohexanedimethanol.

The molar ratio of each raw material for obtaining the (poly) 4-hydroxybenzoic acid ester derivative is (poly) 4-
Hydroxybenzoic acid is (1-150) / (P + 1), other monovalent carboxylic acid is 0-50, and divalent carboxylic acid is 0.
The polyhydric alcohol having a valence of 1 or 3 is used in a ratio of 1 to 50, and the low molecular alcohol having a valence of 2 to 50 is used.
When the use ratio of (poly) 4-hydroxybenzoic acid is low, the color development sensitivity tends to be insufficient, and when it is too high,
There is a tendency that unreacted (poly) 4-hydroxybenzoic acid remains or the high molecular weight becomes insufficient and the background fog easily occurs. If the proportion of the polyhydric alcohol having a valence of 3 or more is low, the color development sensitivity tends to be insufficient, and if it is too high, the background fog is likely to occur. If the molar ratio of the other monovalent carboxylic acid, divalent carboxylic acid or divalent low molecular weight alcohol used as needed is too large, the color developing sensitivity tends to be insufficient.

The (poly) 4-hydroxybenzoic acid ester derivative used in the present invention is obtained by dehydrating the carboxylic acid component (A) and the polyhydric alcohol component (B) with an ordinary carboxylic acid and alcohol by an acid catalyst. It can be prepared by reacting according to a condensation reaction. This (poly) 4-hydroxybenzoic acid ester derivative is often obtained as a mixture even when the carboxylic acid component (A) and polyhydric alcohol component (B) used as raw materials are single compounds. . A mixture is often superior in terms of color development sensitivity.

The (poly) 4-hydroxybenzoic acid ester derivative is often a mixture as described above,
It is difficult to completely define the chemical structure for all of its components. If a typical general formula is shown, the following general formula (3) will be mentioned. This is an example obtained from (poly) 4-hydroxybenzoic acid, a monovalent carboxylic acid, and a trivalent or higher polyhydric alcohol.

[Chemical 5] (However, Z represents a group obtained by removing a hydroxyl group from a polyhydric alcohol. A is 0 or more, b is 1 or more, and c is 0 or more and a
+ B + c is 3 or more, p is an integer of 0 to 2,
R ₃ represents an alkyl group or an aryl group) The more preferable general formula of the component is i mole of HO-B- (OOC-B) p-
COOH, j mol Z (OH) a ', k mol RCOOH (provided that B is a benzene ring, p is 0 or 1, a'is 3 or more, preferably 3 to 22)
When using as a raw material: Here, the raw material composition usually differs depending on the condensation reaction conditions, but (i + k) / a'j = 0.
The range of 5 to 1.5 is preferable, and the compound of the composition formula represented by the formula (3 ′) is generally obtained. [HO-B- (OOC-B) p-COO-] i- (Z) j (OH) (a'j-ik)-(-OOCR) k (3 ') (where Z is a polyhydric alcohol Residue, R is an alkyl group having 1 to 8 carbon atoms, a phenyl group or an alkyl-substituted phenyl group, i
Is preferably j to a'j, k is preferably 0 to a'j / 2, a'j-
ik preferably represents 0 to a'j / 2)

Specific preferred examples of the (poly) 4-hydroxybenzoic acid ester derivative include, for example, formulas (4) to (4)
(7) is mentioned.

[Chemical 6]

Further, the (poly) 4-hydroxybenzoic acid ester derivative used in the present invention when a raw material contains a divalent carboxylic acid, a dihydric alcohol or the like is a polyhydric alcohol having a valence of 3 or more, a dihydric alcohol or the like. A mixed ester or ester mixture, which is a condensation reaction product of alcohols and carboxylic acids such as dicarboxylic acid, (poly) 4-hydroxybenzoic acid and other carboxylic acids, is produced. Although the condensation reaction product varies depending on the raw materials used, the molar ratio used, etc., the general chemical formula can be understood by referring to the above formula (3).

Preferred specific examples of the (poly) 4-hydroxybenzoic acid ester derivative obtained from a raw material containing a divalent carboxylic acid include compounds (8) to (10). The compounds (8) to (10) can be synthesized by using the raw materials shown in Table 1 at the molar ratio shown in Table 1.

[0019]

[Table 1]

The organic acidic substance used in the present invention needs to contain the above-mentioned (poly) 4-hydroxybenzoic acid ester derivative. From the viewpoint of color development sensitivity, it is advantageous that the organic acidic substance used in the present invention is mixed with the (poly) 4-hydroxybenzoic acid ester derivative and another organic acidic substance, but other organic acidic substances are used. Is preferably 50 wt% or less, preferably 20 wt% or less of the total organic acidic substance.

Specific examples of such other organic acidic substances include p-octylphenol, p-tertiary butylphenol, p-phenylphenol, p-hydroxyacetophenone, α-naphthol, p-tertiary octylcatechol, 2, 2'-dihydroxybiphenyl, 1,1
-Bis (p-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis- (3-methyl-4-hydroxyphenyl) propane,
2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane, 2,2-bis (3,5-dichloro-4)
-Hydroxyphenyl) propane, 4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, (3-allyl-4-hydroxyphenyl) sulfone, bis (3,4-dihydroxyphenyl)
Sulfone, 1,1-bis (4-hydroxyphenyl) cyclohexane, bis (4-hydroxyphenyl ether), 1,5-bis (4-hydroxyphenylthio)-
1,3-Dioxaheptane, 4- (4-isopropoxybenzenesulfonyl) phenol, dimethyl 4-hydroxyphthalate, butyl bis (4-hydroxyphenyl) acetate, benzyl p-hydroxybenzoate, 3,5-di-dicarboxylic acid Examples thereof include phenols such as tributylsalicylic acid, organic carboxylic acids such as benzoic acid, phthalic acid and salicylic acid, other dihydroxydiphenyl sulfone isomers, and metal salts such as zinc salicylate.

The amount of the organic acidic substance used varies depending on the type of leuco dye used, but is usually 0.5 to 6 parts by weight, preferably 1.0 to 2.5 parts by weight per 1 part by weight of the leuco dye. Parts by weight.

The sensitizer used in the present invention must contain 4-acetylbiphenyl. In some cases, 4
Compounds known as sensitizers other than -acetylbiphenyl can be mixed and used for the purpose of improving the characteristics, but the amount is preferably 30 wt% or less, preferably 10 wt% or less based on the total sensitizers. If 4-acetylbiphenyl is not used, the stability of the background and the heat resistance will not be improved. The reason why 4-acetylbiphenyl can be preferably used as a sensitizer in the present invention has not been elucidated, but it has not only a particularly good compatibility with (poly) 4-hydroxybenzoic acid ester derivatives but also 4-acetylbiphenyl. Compared with general-purpose sensitizers, it easily dissolves organic acidic substances with large molecular weight and high polarity, improves color development sensitivity, and has a melting point higher than that of general-purpose sensitizers, thus stabilizing the background. Sex,
It is considered to have excellent heat resistance. The amount of the sensitizer used varies depending on the type of leuco dye or organic acid substance used, but is usually 0.5 per 1 part by weight of the leuco dye.
-6 parts by weight, preferably 1.0-2.5 parts by weight.

The heat-sensitive recording material of the present invention comprises a support such as paper and film provided with a heat-sensitive color forming layer. When a high degree of image storability is required, an overcoat layer is formed on the heat-sensitive color forming layer. Is desirable.

Further, when a high degree of image storability is required, it is desirable that a known storage stabilizer be present in the thermosensitive color developing layer, if necessary. Examples of the storage stabilizer include tris (2,6-dimethyl-4-tert-butyl-3-hydroxybenzyl) isocyanurate and tris (3,5-ditert-butyl-4-hydroxybenzyl).
Isocyanurate, tris (2- (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy) ethyl) isocyanurate, 1,3,5-tris (3,5-dimethyl-4-hydroxybenzyl) ) -2,
4,6-trimethylbenzene, 1,1,3-tris (2
-Methyl-4-hydroxy-5-tert-butylphenyl)
Butane, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 4,4 ′
-Butylidene bis (2-tert-butyl-5-methylphenol), 4,4'-thiobis (2-tert-butyl-5-methylphenol), 2,2'-methylenebis (6-tert-butyl-4-methyl) Phenol) and other hindered phenol compounds, 4-benzyloxy-4 ′-(2-methylglycidyloxy) diphenyl sulfone, 4,4′-
Examples thereof include epoxy compounds such as diglycidyloxydiphenyl sulfone, and sodium-2,2′-methylenebis (4,6-ditertiarybutylphenyl) phosphate. These storage stabilizers are usually used in an amount of 0.1 to 10 parts by weight based on 1 part by weight of the dye.

When long-term light resistance is required, it is preferable to add an ultraviolet absorber to the heat-sensitive color forming layer and / or the overcoat layer of the heat-sensitive recording material of the present invention. Examples of the ultraviolet absorber include 2,4
-Dihydroxybenzophenone, 2-hydroxy-4-
2-Hydroxybenzophenones such as methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone and 2,2′-dihydroxy-4-methoxybenzophenone, 2- (2-hydroxy-5-methylphenyl)
Benzotriazole, 2- (2-hydroxy-5-third
Octylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy3,5-
Dicumylphenyl) benzotriazole, 2,2′-methylenebis (4-tertiaryoctyl-6-benzotriazolyl) phenol, 2- (2-hydroxy-3-tertiarybutyl-5-carboxyphenyl) benzotriazole 2- (2-hydroxyphenyl) benzotriazoles such as polyethylene glycol ester, phenyl salicylate, resorcinol monobenzoate, 2,4-ditert-butylphenyl-3,5-ditert-butyl-4-hydroxybenzoate, hexadecyl- Benzoates such as 3,5-ditertiary butyl-4-hydroxybenzoate, substituted oxanilides such as 2-ethyl-2'-ethoxyoxanilide, 2-ethoxy-4'-dodecyloxanilide, ethyl-α. -Cyano-β, β-diphenyl acrylate, methyl-2 Cyano-3-methyl-3-
Cyanoacrylates such as (p-methoxyphenyl) acrylate, 2- (2-hydroxy-4-octoxyphenyl) -s-triazine, 2- (2-hydroxy-).
4-Methoxyphenyl) -4,6-diphenyl-s-triazine, 2- (2-hydroxy-4-propoxy-5)
Examples thereof include triazole triazines such as -methylphenyl) -4,6-bis (2,4-ditertiarybutylphenyl) -s-triazine.

Further, various additives can be added to the heat-sensitive recording material of the present invention depending on its application. Examples of such an additive include a binder for fixing the leuco dye dispersed on the fine particles and the organic acidic substance in a state of being isolated from each other, for example, polyvinyl alcohol (PVA), latex, methyl cellulose, carboxymethyl cellulose, polyacrylic acid. Casein, gelatin, starch or derivatives thereof, whiteness of thermosensitive coloring layer, slipperiness of writing instruments, white pigments added for sticking purpose, for example, calcium carbonate, kaolin, clay, talc, titanium oxide, etc. To be These additives are mixed or separately coated on a support such as paper, film or the like to form a thermosensitive coloring layer.

Further, the heat-sensitive recording material of the present invention preferably has another layer such as an undercoat layer between the heat-sensitive color-developing layer and a support such as paper or film in order to improve color-developing sensitivity.

[0029]

EXAMPLES The present invention will be specifically described below based on Examples and Comparative Examples. Example 1 (1) Preparation of solution A 3- (N, N-dibutylamino) -6 as leuco dye
20 g of methyl-7-anilinofluorane and 100 g of a 10% polyvinyl alcohol aqueous solution were sufficiently ground by a ball mill to prepare a liquid A in which powder having an average particle diameter of 0.8 μm was suspended. (2) Preparation of solution B 20 g of the compound (4) as an organic acidic substance and 100 g of a 10% aqueous solution of polyvinyl alcohol were sufficiently ground by a ball mill to prepare a solution B in which powder having an average particle size of 0.8 μm was suspended. (3) 4-acetylbiphenyl 20 g and 10% as a sensitizer for the preparation of solution C
100 g of an aqueous polyvinyl alcohol solution was sufficiently ground with a ball mill to prepare a liquid D in which powder having an average particle diameter of 0.8 μm was suspended. (4) Preparation of thermosensitive recording paper The above dispersions A, B and C were mixed in a weight ratio of 1: 2: 2, and 200 g of this mixed solution was mixed with 50 g of calcium carbonate.
Was added and sufficiently dispersed to form a coating liquid. The coating liquid was applied onto a base paper and dried to prepare a thermal recording paper having a coating amount of 6 g / m ² after drying.

(5) Coloring test The thermal recording paper thus prepared was subjected to a dynamic coloring test (24 V, 1.0 ms) to measure the coloring density of the printed part and the background. The dynamic color development test was performed by using a printing tester (manufactured by Okura Electric Co., Ltd.) and measuring the color development density using a Macbeth reflection densitometer RD-914. (6) Humidity resistance test The thermosensitive recording paper that has been subjected to the dynamic color development test is placed in a thermo-hygrostat (50
C., relative humidity 90%) for 24 hours, after which the color density of the printed area and background is determined by Macbeth reflection densitometer RD-914.
The measurement was performed by using. (7) Plasticizer resistance test A vinyl chloride wrap is brought into close contact with the entire printing surface of the thermosensitive recording paper subjected to the dynamic color development test. This test thermal recording paper was stored in a dryer (40 ° C.) for 24 hours, and then the color density of the printed part and the background was measured by using a Macbeth reflection densitometer RD-914. (8) Heat resistance test The thermosensitive recording paper that had been subjected to the dynamic color development test was dried in a thermostatic dryer (80
C.) for 24 hours, after which the color density of the printed area and the background was measured using a Macbeth reflection densitometer RD-914. (9) Light resistance test A method of irradiating a thermosensitive recording paper that has been subjected to a dynamic color development test with a fade meter for 12 hours, and then measuring the color density of the printed part and the background using a Macbeth reflection densitometer RD-914. I went there. Table 2 shows the results of the dynamic color development test, the humidity resistance test, the plasticizer resistance test, the heat resistance test, and the light resistance test.

Example 2 A thermosensitive recording paper was prepared and carried out in exactly the same manner as in Example 1 except that the compound (5) was used in place of the compound (4) in the preparation of the dispersion B of Example 1. The test was carried out as in Example 1. The results are shown in Table 2.

Example 3 A thermosensitive recording paper was prepared and carried out in exactly the same manner as in Example 1 except that Compound (6) was used in place of Compound (4) in the preparation of Dispersion B of Example 1. The test was carried out as in Example 1. The results are shown in Table 2.

Example 4 A thermosensitive recording paper was prepared and carried out in the same manner as in Example 1 except that the compound (7) was used in place of the compound (4) in the preparation of the dispersion B of Example 1. The test was carried out as in Example 1. The results are shown in Table 2.

Example 5 A thermosensitive recording paper was prepared and carried out in exactly the same manner as in Example 1 except that the compound (8) was used in place of the compound (4) in the preparation of the dispersion B of Example 1. The test was carried out as in Example 1. The results are shown in Table 2.

Example 6 A thermosensitive recording paper was prepared and carried out in exactly the same manner as in Example 1 except that the compound (9) was used in place of the compound (4) in the preparation of the dispersion B of Example 1. The test was carried out as in Example 1. The results are shown in Table 2.

Example 7 A thermosensitive recording paper was prepared and carried out in exactly the same manner as in Example 1 except that the compound (10) was used in place of the compound (4) in the preparation of the dispersion B of Example 1. The test was carried out as in Example 1. The results are shown in Table 2.

Comparative Example 1 Thermal recording was carried out in the same manner as in Example 1 except that oxalic acid di (4-methylbenzyl ester) was used in place of 4-acetylbiphenyl in the preparation of Dispersion C of Example 1. Paper was prepared and tested as in Example 1.
The results are shown in Table 2.

Comparative Example 2 A thermosensitive recording paper was prepared in the same manner as in Example 1 except that acetoacetic acid-o-chloroanilide was used in place of 4-acetylbiphenyl in the preparation of Dispersion C of Example 1. Then
The test was carried out in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 3 A thermosensitive recording paper was prepared in the same manner as in Example 1 except that diphenyl sulfone was used instead of 4-acetylbiphenyl in the preparation of Dispersion C of Example 1, and Example 1 was used. The test was conducted in the same manner as in. The results are shown in Table 2.

Comparative Example 4 A thermosensitive recording paper was prepared in the same manner as in Example 1 except that stearic acid amide was used in place of 4-acetylbiphenyl in the preparation of the dispersion C of Example 1. The test was conducted in the same manner as in the case of 1. The results are shown in Table 2.

[0041]

[Table 2]

[0042]

The heat-sensitive recording material of the present invention is excellent in the whiteness of the background and the thermal responsiveness, and is resistant to plasticizer, resistance to moist heat, heat resistance,
It is a heat-sensitive recording material having excellent recorded performance such as light fastness and excellent storage stability on the background, and good performance balance.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasunari Maeda             No.46, Nakahara-no-hama, Tobata-ku, Kitakyushu, Fukuoka             Local 80 Inside Nippon Steel Chemical Research Center (72) Inventor Shuichiro Hase             No.46, Nakahara-no-hama, Tobata-ku, Kitakyushu, Fukuoka             Local 80 Inside Nippon Steel Chemical Research Center F term (reference) 2H026 BB02 BB24 DD02 DD45 DD53                       FF01

Claims (2)

[Claims] 1. A thermosensitive recording material comprising a support and a thermosensitive coloring layer containing a colorless or pale leuco dye at room temperature and an organic acidic substance that reacts with the leuco dye to develop a color when heated. As a substance, the general formula (1)
A condensation reaction product of a carboxylic acid component (A) containing (poly) 4-hydroxybenzoic acid as an essential component and a polyhydric alcohol component (B) containing a polyhydric alcohol having a valence of 3 or more as an essential component And a 4-acetylbiphenyl as a sensitizer. [Chemical 1] (However, p represents an integer of 0 to 2) 2. The heat-sensitive recording material according to claim 1, wherein the trihydric or higher polyhydric alcohol is a compound represented by the following general formula (2). [Chemical 2] (However, n represents an integer of 0 to 9, and R ₁ and n R ₂ are each independently a hydroxymethyl group or a carbon number of 1 to 8.
Represents the alkyl group of