JPH09314994A - Thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a low costed thermal transfer recording material which has an excellent heat response property, is simultaneously little in fogging on texture, and excellent in oil resistance by a method wherein one or more kinds of a phenolic derivative having a hydrazide skeleton expressed by the specific formula are contained in a thermal coloring layer. SOLUTION: One or more kinds of phenolic derivative having a hydrazide skeleton expressed by the formula I or formula II are contained as an organic acidic material, i.e., a developer in a thermal coloring layer. In the formula I, R1 expresses a 1-8C alkyl group or aryl group, X expresses a lower alkyl group, an alkoxyl group or a halogen atom, (n) is an integer of 0-4, and (m) is an integer of 1-3. However, m+n is 5 or under. In the formula II, R2 expresses a bivalent aliphatic hydrocarbon group or a bivalent aromatic group, X expresses a lower alkyl group, an alkoxyl group or a halogen atom, (n) is an integer of 0-4, and (m) is an integer of 1-3. However, m+n is 5 or under.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a thermal recording material,
In particular, the present invention relates to a heat-sensitive recording material having excellent thermal responsiveness of a recorded image, less fog on the background, and excellent storage stability of the recorded image, that is, excellent oil resistance and humidity resistance of toluene and the like.

[0002]

2. Description of the Related Art In recent years, the amount of information has increased due to the increasing use of information. In the field of information recording for recording such information, various recording methods and recording materials have been studied and put to practical use. I have. Among them, the thermal recording method can obtain a recorded image by simply heating the thermal recording material and does not require a complicated developing step. In many cases, inexpensive paper is used as a support for thermosensitive recording materials, which is advantageous in that the obtained recording material has a feeling similar to plain paper. It has been adopted in many fields such as computer output, printers such as calculators, recorders for various measuring instruments, facsimiles, automatic ticketing machines, thermal copying machines and labels.

However, with the spread of these OA devices,
In recent years, thermal paper sales competition has intensified, and thermal paper manufacturers have been forced to reduce costs. In addition, the spread of word processors to ordinary households has almost stopped for manufacturers of OA equipment, and in order to spread a plurality of units, high-performance functions different from conventional functions have been required. . As one of them, when the conventional heat-sensitive recording material is used as a label for a POS system or the like, in particular, a supermer is used.
The label used on the ket or the like often comes into contact with water or oils, and has a defect that the recorded image is significantly discolored. For this reason, there has been a demand for a chemical agent having good thermal response as in the past, which is inexpensive and can stabilize a printed image.

[0004] Therefore, as an attempt to solve such problems in the conventional thermosensitive recording material, it has been proposed to add various substances to the thermosensitive coloring layer to improve the storage stability of the recorded image. Have been. Japanese Examined Japanese Patent Sho 63-460
JP-A-59-7 discloses a method in which a diphenylsulfone derivative having a phenol skeleton as a color developer and a dibenzyl ester of phthalic acid as a sensitizer are contained in JP-A-59-7.
No. 3990, No. 61-160292, No. 60-176794, No. 1-20918.
No. 4, JP-A-4-37589 discloses a method of incorporating a sulfonic acid ester as a sensitizer.
No. 147357 and JP-A No. 5-148220 propose a method of incorporating a sulfonylurea compound as a developer. However, although the storage stability is improved by any of the techniques, it is not satisfactory, and it cannot be said that the performance of each drug is sufficiently brought out.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of such a viewpoint.
It is an object of the present invention to provide an inexpensive heat-sensitive recording material which has excellent heat response, has less fogging on the background, and has excellent storage stability of recorded images, that is, excellent oil resistance against toluene and the like.

[0006]

That is, the present invention provides a heat-sensitive coloring layer containing a colorless or pale-colored leuco dye at room temperature and an organic acid substance which reacts with the leuco dye by heating to form a color on a support. In the thermal recording material provided,
A heat-sensitive recording material comprising the heat-sensitive recording layer containing one or more phenol derivative having a hydrazide skeleton represented by the following general formula (1) or (2).

Embedded image (In the formula, R ₁ is an alkyl group or aryl group having 1 to 8 carbon atoms, X is a lower alkyl group, an alkoxy group or a halogen atom, n is an integer of 0 to 4, and m is an integer of 1 to 3. (However, m + n is 5 or less.)

Embedded image (In the formula, R ₂ is a divalent aliphatic hydrocarbon group or a divalent aromatic group, X is a lower alkyl group, an alkoxy group or a halogen atom, n is an integer of 0 to 4, and m is 1 to Represents an integer of 3, provided that m + n is 5 or less.)

Hereinafter, the present invention will be described in detail. 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 3,3-bis (p-dimethylaminophenyl)-
Triallylmethane dyes such as 6-dimethylaminophthalide, diphenylmethane dyes such as 4,4′-bisdimethylaminobenzhydridobenzyl ether, and thiazine dyes such as benzoylleuco methylene blue, for example, Spiro dyes such as 3-methylspirodinaphthopyran and, for example, 7'-anilino-3 '
Examples thereof include fluorane dyes such as-(dibutylamino) -6'-methylfluorane, and other 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.

In the present invention, it is preferable to use a heat-soluble substance as a sensitizer in the heat-sensitive coloring layer.
As such a sensitizer, a heat-soluble organic compound having a melting point of 50 to 150 ° C. is used, and examples thereof include p-benzylbiphenyl, m-terphenyl, 1-hydroxy-2-naphthoic acid phenyl ester, benzylnaphthyl ether,
Dibenzyl terephthalate, benzyl p-benzyloxybenzoate, diphenyl carbonate, ditolyl carbonate, 1,2-
Examples thereof include bis (m-tolyloxy) ethane, oxalic acid diesters, hydrazides, sulfonyl hydrazides and the like.

In the present invention, one or more phenol derivatives having a hydrazide skeleton represented by the above general formula (1) or (2) are added to an organic acidic substance,
That is, it is contained in the thermosensitive coloring layer as a developer.

The alkyl group represented by R ₁ in the general formula (1) includes a group represented by C _n H _{2n + 1} (preferably n is 1 to 8), and the aryl group is a phenyl group. Examples include a toluyl group. Further, the lower alkyl group of X includes a methyl group, an ethyl group, a propyl group and the like, the alkoxy group includes a methoxy group, an ethoxy group, a propoxy group and the like, and the halogen atom includes a fluorine, chlorine and bromine atom. Etc. N in the general formula (1) is 0 to 4
, M is an integer of 1 to 3, m + n is 5 or less,
Preferably, m is 1.

Further, R in the general formula (2)_TwoThe two-valued
Examples of the aliphatic hydrocarbon group include C_nH _2n(N is 1-8)
There is a group represented by phenylene as a divalent aromatic group.
And divalent aromatic groups having aromatic rings at both ends.
It is. Then, a divalent aromatic group whose both ends are aromatic rings
Preferred examples include those represented by the following general formula (3).
And a 4-ring aromatic group. The general formula (2)
X in is similar to X in the general formula (1).
There are things. N in the general formula (2) is 0 to 4
An integer, m is an integer of 1 to 3, m + n is 5 or less, and
More preferably, m is 1.

Embedded image Z in the general formula (3) is -O-, -CH.
_{2 -, - CO -, -} S -, - SO 2 - or -CF ₂ - and the like.

Specific preferred examples of the phenol derivative having a hydrazide skeleton include the following compounds 1 to 6
And the like. [Compound 1: melting point = 233 ° C.]

[Chemical 6] [Compound 2: melting point = 198 ° C.]

[Chemical 7] [Compound 3: melting point = 180 ° C.]

Embedded image [Compound 4: melting point = 215 ° C.]

Embedded image [Compound 5: melting point = 210 ° C.]

Embedded image [Compound 6: melting point = 223 ° C.]

Embedded image

These compounds can be synthesized by reacting hydroxybenzaldehydes with hydrazides in a solvent such as isopropyl alcohol. For example, 4-hydroxybenzaldehyde and benzhydrazide are stirred at room temperature in isopropyl alcohol,
The product is filtered to give compound 1.

When a phenol derivative having a hydrazide skeleton is used as the organic acidic substance, one or more of these can be used. The amount of these used, depending on the type of leuco dye, sensitizer and organic acidic substance used, etc.
The organic acid substance and the sensitizer are 1 to 6 parts by weight, preferably 1.5 to 2.5 parts by weight, per 1 part by weight of the leuco dye.

Further, in addition to these, it is added in order to improve the storage stability of the color-developed part, and the thermal response is slightly inferior, but for example, organic acid substances such as epoxy resin, zinc stearate, zinc salicylate, etc. You may use together the metal salt of.

Further, various additives can be added to the heat-sensitive recording material of the present invention depending on its application.
As such an additive, a binder for fixing the leuco dye and the organic acidic substance dispersed in the form of fine particles in a state of being isolated from each other, for example, polyvinyl alcohol (PVA),
Methylcellulose, carboxymethylcellulose, polyacrylic acid casein, gelatin, starch or derivatives thereof, and white pigments that improve the whiteness of the thermosensitive coloring layer, the slipperiness of writing instruments, sticking, etc., for example, calcium carbonate, kaolin, clay, talc. , Titanium oxide, etc. These additives may be mixed or separated,
It is coated on a support such as a paper film to form a thermosensitive coloring layer. Further, this thermosensitive coloring layer may have other layers such as a protective layer.

[0017]

In the heat-sensitive recording material of the present invention, when the leuco dye constituting the heat-sensitive color-developing layer is colored by the organic acidic substance, the phenol derivative having a hydrazide skeleton contained in the heat-sensitive color-developing layer forms a printed image. It is believed to produce robustness.

[0018]

The present invention will be specifically described below based on examples and comparative examples. Example 1 (1) Preparation of Solution A 11.5 parts by weight of Compound 1 as the above phenol derivative, 11.5 parts by weight of diphenyl sulfone, and 5% by weight of PV
46 parts by weight of the A aqueous solution and 46 parts by weight of water were pulverized and mixed using a sand mill to prepare an A solution having an average particle size of 0.6 μm. (2) Preparation of solution B 7'-anilino-3 '-(dibutylamino) -6'-methylfluorane 5.5 parts by weight and 59.5% by weight PVA aqueous solution 49.5 parts by weight were pulverized and mixed using a paint shaker. Then, a liquid B having an average particle size of 0.8 μm was prepared. (3) Preparation of thermal recording paper 20 parts by weight of liquid A, 10 parts by weight of liquid B, 1 part by weight of paraffin wax emulsion (hydrin Z-7 manufactured by Chukyo Yushi Co., Ltd.), 4 parts by weight of paraffin wax emulsion (hydrin P-7 manufactured by Chukyo Yushi Co., Ltd.) Parts, 10 parts by weight of 50% calcium carbonate dispersion and 11.5 parts by weight of 10% by weight PVA aqueous solution are mixed to prepare a coating liquid, the coating liquid is coated on a base paper and dried, and the coating amount after drying. A thermal recording paper of 6 g / m ² was prepared.

(4) Color development test The thermal recording paper thus prepared was subjected to a dynamic color development test. The dynamic color test uses a printing tester (manufactured by Okura Electric Co., Ltd.) and uses 24 V for sensitivity evaluation and humidity resistance test.
27V, 1.9m for toluene resistance test in 1.0ms
s for printing, and the color density is determined by Macbeth reflection densitometer RD-
914 was used. (5) Humidity resistance test method Thermal recording paper (24 V, 1.0 m
s) was stored in a thermo-hygrostat (40 ° C., relative humidity 90%) for 10 hours, and then the color density of the printed portion was measured using a Macbeth reflection densitometer RD-914. The residual rate was calculated by the following mathematical formula (1). Residual rate = (AB) / C (1) (where A represents the dynamic color density after the humidity resistance test, and B
Indicates a value obtained by subtracting the color density of the background before the humidity resistance test from the color density of the background after the humidity resistance test, and C indicates the dynamic color density before the humidity resistance test. (6) Toluene resistance test method Thermal recording paper (27 V, 1.9 m) that has been subjected to a dynamic color development test.
After immersing s) in toluene for 1 minute, the color density of the printed portion was measured using a Macbeth reflection densitometer RD-914. The residual rate was calculated by the following mathematical formula (2). Residual rate = (D−E) / F (2) (In the formula, D represents the dynamic color density after the toluene resistance test, and E represents the color density of the background after the toluene resistance test and before the toluene resistance test. The value obtained by subtracting the color development density of the background is shown, and F shows the dynamic color development density before the toluene resistance test.) The results of the sensitivity and humidity resistance tests are shown in Table 1, and the results of the toluene resistance test are shown in Table 2. Shown in.

Example 2 A thermosensitive recording paper was prepared in the same manner as in Example 1 except that Compound 2 was used in place of Compound 1 in the preparation of the liquid A of Example 1. A color development test was conducted in the same manner as in. The results of the sensitivity and humidity resistance test are shown in Table 1, and the results of the toluene resistance test are shown in Table 2.

Example 3 In the case of Example 1, a thermal recording paper was prepared in the same manner as in Example 1 except that Compound 3 was used in place of Compound 1 in the preparation of the liquid A of Example 1. A color development test was conducted in the same manner as in. The results of the sensitivity and humidity resistance test are shown in Table 1, and the results of the toluene resistance test are shown in Table 2.

Example 4 A thermosensitive recording paper was prepared in the same manner as in Example 1 except that Compound 4 was used in place of Compound 1 in the preparation of the solution A of Example 1. A color development test was conducted in the same manner as in. The results of the sensitivity and humidity resistance test are shown in Table 1, and the results of the toluene resistance test are shown in Table 2.

Example 5 In the case of Example 1, a thermal recording paper was prepared in the same manner as in Example 1 except that Compound 5 was used in place of Compound 1 in the preparation of the liquid A of Example 1. A color development test was conducted in the same manner as in. The results of the sensitivity and humidity resistance test are shown in Table 1, and the results of the toluene resistance test are shown in Table 2.

Example 6 In the case of Example 1, a thermal recording paper was prepared in the same manner as in Example 1 except that Compound 6 was used in place of Compound 1 in the preparation of the liquid A of Example 1. A color development test was conducted in the same manner as in. The results of the sensitivity and humidity resistance test are shown in Table 1, and the results of the toluene resistance test are shown in Table 2.

Comparative Example 1 A thermosensitive recording paper was prepared in the same manner as in Example 1 except that Bisphenol A was used in place of Compound 1 in the preparation of solution A in Example 1. A color development test was conducted in the same manner as in the case of 1. Table 1 shows the results of the sensitivity and humidity resistance tests.
The results of the toluene resistance test are shown in Table 2.

Comparative Example 2 Thermosensitive recording was carried out in the same manner as in Example 1 except that 4-hydroxy-4'-isopropoxydiphenyl sulfone was used in place of the compound 1 in the preparation of the liquid A of Example 1. Paper was prepared and a color development test was conducted in the same manner as in Example 1.
The results of the sensitivity and humidity resistance test are shown in Table 1, and the results of the toluene resistance test are shown in Table 2.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

INDUSTRIAL APPLICABILITY The hydrazide skeleton phenol derivative according to the present invention has excellent thermal response as a chemical agent for heat-sensitive recording materials, and can significantly improve the storage stability of recorded images, that is, the oil resistance and humidity resistance of toluene and the like. .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroe Nonaka 556-4 Takyu, Munakata City, Fukuoka Prefecture

Claims (1)

[Claims] 1. A thermosensitive 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 produce a color when heated. A thermosensitive recording material comprising one or more phenol derivatives having a hydrazide skeleton represented by the formula (1) or (2) contained in the thermosensitive coloring layer. Embedded image (In the formula, R ₁ is an alkyl group or aryl group having 1 to 8 carbon atoms, X is a lower alkyl group, an alkoxy group or a halogen atom, n is an integer of 0 to 4, and m is an integer of 1 to 3. Representation, provided that m + n is 5 or less.) (In the formula, R ₂ is a divalent aliphatic hydrocarbon group or a divalent aromatic group, X is a lower alkyl group, an alkoxy group or a halogen atom, n is an integer of 0 to 4, and m is 1 to Represents an integer of 3, provided that m + n is 5 or less.)