JPH06286316A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material excellent not only in thermal response but also in storage stability (heat resistance). CONSTITUTION:In a thermal recording material wherein a thermal color forming layer containing a leuco dye colorless or light-colored at the normal temp. and a org. acidic substance reacting with the leuco dye by heating to allow the leuco dye to form a color is provided on a support, a glycerol derivative represented by general formula Ar1OCH2CH(OR)CH2OAR, (1) (wherein R is an aryl group, a 1-8C alkyl group or a cycloalkyl group and Ar1 and Ar2 are an aryl group and may be same or different) is added to the thermal color forming layer.

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, and more particularly to a heat-sensitive recording material excellent in heat response and storage stability (heat resistance).

[0002]

2. Description of the Related Art In recent years, the amount of information has increased with the diversification of information, and various recording systems and recording materials have been studied and put into practical use in the field of information recording for recording such information. There is. Among them, the heat-sensitive recording method can obtain a recorded image by simply heating the heat-sensitive recording material and does not require a complicated developing step. Inexpensive and inexpensive paper is often used as a support for the heat-sensitive recording material, but in this case, there is an advantage that the obtained recording material has a feeling similar to that of plain paper, and a computer is used. Output, printers such as calculators, recorders for various measuring instruments, facsimiles, automatic ticketing machines, and thermal copying machines.

As a heat-sensitive recording material used for these purposes, conventionally, a leuco dye which is colorless or light-colored at room temperature and an organic acidic substance such as a phenolic compound which reacts with the leuco dye by heating to develop a color. It is known that a thermosensitive color-forming layer containing is provided on a support such as paper, synthetic paper or synthetic resin film (see, for example, Japanese Examined Patent Publication No.
-4160 and Japanese Patent Publication No. 45-14039).
However, these conventional heat-sensitive recording materials have a problem that their thermal responsiveness is insufficient and, when used for high-speed recording, sufficient color density cannot be obtained. Also in this information recording field, the time for heating the thermal head is short, and sufficient density can be obtained at a low voltage, thereby improving the recording speed and supporting high-speed recording. Has been requested.

Therefore, as an attempt to solve the problems in the conventional heat-sensitive recording material, it has been proposed to add a thermoplastic substance to the heat-sensitive color forming layer to improve the thermal response. (JP-B-51-27599, JP-A-48-19231 and JP-B-63-30,
878). However, even in such a technique, since the demand for high-speed recording in recent years has been further increased, satisfactory results have not yet been obtained regarding the thermal responsiveness, and the thermal responsiveness has not been improved. If the sensitivity of the heat-sensitive recording material is improved to improve the sensitivity, so-called background fog is likely to occur when the material is used in, for example, a facsimile.

[0005]

SUMMARY OF THE INVENTION The present invention was devised in view of such a viewpoint, and its purpose is to:
An object of the present invention is to provide a heat-sensitive recording material which has excellent thermal responsiveness and storage stability (heat resistance) at the same time.

[0006]

That is, the present invention provides a thermosensitive coloring layer on a support containing a colorless or pale-colored leuco dye at room temperature and an organic acidic substance that reacts with the above leuco dye to develop a color. In the thermosensitive recording material to be provided, the thermosensitive coloring layer has the following general formula (1) Ar ₁ OCH ₂ CH (OR) CH ₂ OAr ₂ (1) (wherein R is an aryl group, a carbon number of 1 to 1). Represents an alkyl group or a cycloalkyl group of 8. Also, Ar ₁ and A
r ₂ represents an aryl group, and may be the same or different. ), And a heat-sensitive recording material containing one or a mixture of two or more selected from glycerol derivatives having a melting point in the range of 50 to 150 ° C.

In the present invention, the leuco dye used as a color former is a colorless or pale color at room temperature and is a substance that reacts with an acidic substance under heating to develop a color, and 3,3-bis (p-dimethylamino) (Phenyl) -6-dimethylaminophthalide and other triallylmethane dyes, 4,4'-bisdimethylaminobenzhydridobenzyl ether and other diphenylmethane dyes, benzoylleucomethylene blue and other thiazine dyes, and 3-methyl Examples thereof include spiro-based dyes such as spirodinaphthopyran, and other dyes such as leuco auramine-based dyes, indoline-based dyes, and indigo-based dyes. When used, these color formers may be used alone or in combination of two or more.

The organic acidic substance used together with the above leuco dye is a substance which comes into contact with the leuco dye by heating to become a developer, and various phenol compounds and organic acids can be mentioned. As the organic acidic substance used for this purpose, those which are solid at room temperature and liquefy or vaporize at 50 ° C. or higher are preferable. Specific examples of such organic acidic substances include phthalic anhydride, gallic acid, salicylic acid, 4,4′-isopropylidene (2-chlorophenol), 4,4′-isopropylidene (2-t-butylphenol). , 4,4'-sec-Butylidenephenol, 4,4 '-(1-methyl-n-hexylidene) diphenol, 4-phenylphenol, 4-hydroxydiphenoxide methyl-4-hydroxybenzoate, 4-hydroxyacetophenone Anilide salicylate, 4,4'-cyclohexylidene diphenol,
4,4'-Cyclohexylidenebis (2-methylphenol), 4,4'-Benzylidenephenol, 4,4'-Thiobis (6-t-butyl-3-methylphenol), Bis (4-hydroxyphenyl) Examples thereof include sulfone, 4-hydroxy-4′-isopropoxydiphenyl sulfone, novolac type phenol resin, halogenated novolac type phenol resin, α-naphthol and β-naphthol. These organic acidic substances may be used alone or in combination of two or more.

The glycerol derivative used in the present invention is
It has a melting point lower than that of the leuco dye and / or the organic acidic substance, or one of them, and has a solubility in the leuco dye and / or the organic acidic substance to dissolve one or both of them and accelerate the reaction between them. That is, a function as a color development accelerator. In the present invention, the thermosensitive coloring layer is represented by the general formula (1) and has a melting point of 50 to 50.
One or two glycerol derivatives in the range of 150 ° C
Mix more than one seed.

In the general formula (1), R is an aryl group,
An alkyl group having 1 to 8 carbon atoms or a cycloalkyl group having 1 to 8 carbon atoms, each of which may have a substituent. As the aryl group, in addition to a phenyl group, a naphthyl group, a biphenyl group, etc., one or more of these substituted with an alkyl group such as a methyl group, an ethyl group, a propyl group, a halogen group, a hydroxy group, an alkoxy group,
Some are substituted with 1 or 2 or more aryloxy groups, nitro groups and the like. As the alkyl group, a methyl group, an ethyl group,
In addition to propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group and the like, there are those in which halogen, hydroxy group, alkoxy group, allyloxy group, nitro group and the like are substituted by 1 or 2 or more. As the cycloalkyl group, in addition to a cyclopentyl group, a cyclohexyl group and the like, those in which one or more alkyl groups such as a methyl group, an ethyl group and a propyl group are substituted, a halogen, a hydroxy group, an alkoxy group, an allyloxy group , Nitro groups and the like are substituted by 1 or 2 or more.

Ar ₁ and Ar ₂ are aryl groups which may be the same or different and may have a substituent. As the aryl group, in addition to a phenyl group, a naphthyl group, a biphenyl group, and the like, those in which one or more alkyl groups such as a methyl group, an ethyl group, and a propyl group are substituted,
Some of them are substituted with one or more halogen, hydroxy group, alkoxy group, allyloxy group, nitro group and the like.

Specific examples include the following compounds.

[Chemical 1]

[Chemical 2]

[Chemical 3]

[Chemical 4]

[Chemical 5]

[Chemical 6]

[Chemical 7]

[Chemical 8]

[Chemical 9]

In use, one or more selected from these can be used, and other sensitizers may be used in combination. The amount of these used varies depending on the type of the leuco dye and the organic acidic substance used, but is usually 0.5 to 30 parts by weight, preferably 1 to 10 parts by weight per 1 part by weight of the leuco dye. is there. Further, various additives can be added to the heat-sensitive recording material of the present invention depending on its use and the like. Examples of such an additive include polyvinyl alcohol (PVA), methyl cellulose, carboxymethyl cellulose, polyacrylic acid casein, gelatin, starch, or the like which adheres a leuco dye and an organic acidic substance dispersed in a fine particle state in a state of being isolated from each other. Binders such as these derivatives, whiteness of thermosensitive coloring layer, slipperiness of writing instruments, white pigments or aliphatic metal salts such as calcium carbonate, kaolin, clay, talc, titanium oxide added for the purpose of sticking, , Epoxy resin, zinc stearate, which is added for the purpose of long-term storage stability of the colored part and the uncolored part,
Examples include zinc salicylate. These additives are mixed or separately coated on a support such as a paper film to form a thermosensitive color developing layer. Further, the thermosensitive coloring layer may have other layers such as a protective layer.

[0014]

In the heat-sensitive recording material of the present invention, the glycerol derivative contained in the heat-sensitive color forming layer has a lower melting point or sublimation than the leuco dye and / or the organic acidic substance constituting the heat-sensitive color forming layer. It is considered that the compound has a dot and has a solubility in a leuco dye and / or an acidic substance, and acts as a color development accelerator that dissolves one or both of them and accelerates the reaction of both of them.

[0015]

EXAMPLES 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 6>, bisphenol A1
1.5 parts by weight, 46 parts by weight of 5 wt% -PVA aqueous solution, and 46 parts by weight of water were pulverized and mixed using a sand mill to prepare an A liquid having an average particle size of 0.6 μm. (2) Preparation of solution B 3- (N-isoamyl-N-ethylamino) -6-methyl-7-anilinofluorane 5.5 parts by weight, and 5 w
49.5 parts by weight of a t% -PVA aqueous solution was pulverized and mixed using a paint shaker to prepare a liquid B having an average particle size of 0.8 μm. (3) Preparation of thermal recording paper 20 parts by weight of A solution, 10 parts by weight of B solution, paraffin wax emulsion (Hydrin Z-7 manufactured by Chukyo Yushi Co., Ltd.)
1 part by weight, paraffin wax emulsion (Chukyo Yushi Co., Ltd .: Hydrin P-7) 4 parts by weight, 50% calcium carbonate dispersion liquid 10 parts by weight, and 10 wt% -PVA
A coating liquid was prepared by mixing 11.5 parts by weight of the aqueous solution, and the coating liquid was applied onto a base paper and dried, and the coating amount after drying was 6 g / m 2.
A thermal recording paper of ² was obtained.

The thermal recording paper thus obtained was subjected to a dynamic color development test and a static color development test at 70 ° C. The results are shown in Table 1. The dynamic color test uses a printing tester (Okura Electric Co., Ltd.), and the static color test uses a stamp type color tester (Daei Kagaku Seiki Co., Ltd.).
(Made by) and the color density of Macbeth reflection densitometer RD-9
14 was used for measurement.

Example 2 A thermosensitive recording paper was prepared in the same manner as in Example 1 except that <Compound 8> was used in place of <Compound 6> in the preparation of the liquid A of Example 1. Then, the color development test was conducted in the same manner as in the case of Example 1 above. The results are shown in Table 1.

Example 3 A thermosensitive recording paper was prepared in the same manner as in Example 1 except that <Compound 9> was used in place of <Compound 6> in the preparation of the liquid A of Example 1. Then, the color development test was conducted in the same manner as in the case of Example 1 above. The results are shown in Table 1.

Example 4 In the preparation of solution B of Example 1, 3-dibutylamino- was used instead of 3- (N-isoamyl-N-ethylamino) -6-methyl-7-anilinofluorane. 6-methyl-7
-A thermosensitive recording paper was prepared in the same manner as in Example 1 except that anilinofluoran was used, and a color development test was performed in the same manner as in Example 1 above. The results are shown in Table 1.

Example 5 In the preparation of solution B of Example 2, 3-dibutylamino- was used instead of 3- (N-isoamyl-N-ethylamino) -6-methyl-7-anilinofluorane. 6-methyl-7
-A thermosensitive recording paper was prepared in the same manner as in Example 1 except that anilinofluoran was used, and a color development test was performed in the same manner as in Example 1 above. The results are shown in Table 1.

Example 6 In preparing the solution B of Example 3, 3-dibutylamino- was used instead of 3- (N-isoamyl-N-ethylamino) -6-methyl-7-anilinofluorane. 6-methyl-7
-A thermosensitive recording paper was prepared in the same manner as in Example 1 except that anilinofluoran was used, and a color development test was performed in the same manner as in Example 1 above. The results are shown in Table 1.

Comparative Example 1 A thermosensitive recording paper was prepared in the same manner as in Example 1 except that stearamide was used instead of <Compound 6> in the preparation of the liquid A of Example 1. A color test was conducted in the same manner as in Example 1 above. The results are shown in Table 1.

Comparative Example 2 A thermosensitive recording paper was prepared in the same manner as in Example 1 except that stearamide was used in place of <Compound 6> in the preparation of the liquid A of Example 4. A color test was conducted in the same manner as in Example 1 above. The results are shown in Table 1.

[0024]

[Table 1]

[0025]

INDUSTRIAL APPLICABILITY The glycerol derivative of the present invention has excellent thermal responsiveness and improved stability (heat resistance) as a color-forming accelerator for heat-sensitive recording materials.

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. In the color forming layer, the following general formula (1) Ar ₁ OCH ₂ CH (OR) CH ₂ OAr ₂ (1) (wherein R represents an aryl group, an alkyl group having 1 to 8 carbon atoms or a cycloalkyl group) Also, Ar ₁ and A
r ₂ represents an aryl group, and may be the same or different. ) And having a melting point in the range of 50 to 150 ° C., one or a mixture of two or more selected from glycerol derivatives.