JPH0872406A - Thermal recording material - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a heat-sensitive recording material which has a good initial color density, has little decolorization of a color-developed part due to a plasticizer, etc. and has excellent storage stability. [Structure] The heat-sensitive recording material of the present invention comprises:
It is characterized by containing bis (4-hydroxyphenyl) sulfone and at least one of the acylacetic acid anilide derivatives represented by the following general formula (I). Embedded image

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 having improved storage stability, more specifically, bis (4-hydroxyphenyl) sulfone (hereinafter referred to as "bisphenol S") and a specific acylacetic acid anilide. The present invention relates to a heat-sensitive recording material containing not only excellent color development sensitivity but also improved storage stability such as heat resistance, light resistance and oil resistance by containing a derivative.

[0002]

2. Description of the Related Art A heat-sensitive recording material generally comprises a colorless or light-colored color-forming substance and a color-developing agent which develops the color-forming substance when subjected to heat, a sensitizer and a binder. It is produced by coating the surface of a support such as paper, synthetic paper, plastic film or sheet together with other additives. And
In a recording device, when a heating element such as a thermal head or a heating pen comes into contact, the color-forming substance reacts with a developer to develop a black color or the like for recording. Such a recording material (thermosensitive recording material) does not require complicated processing such as development and fixing as compared with other recording materials, and recording can be obtained with a relatively simple device in a short time. Not only recording materials for copying books, documents, etc., but also various measuring recording papers, computers, facsimiles, telex, boarding because of the advantages of low generation, low environmental pollution, low cost, etc. It is widely used as a recording material for vending machines such as tickets, prepaid cards, and labels.

In a conventional heat-sensitive recording material, an appropriate combination of a color-forming substance (leuco dye), a color-developing agent for thermally developing the color-developing substance and a sensitizer used as necessary is used to obtain an initial composition. From the viewpoints of color development sensitivity and dirt on the background (background fogging), what is practically satisfactory is obtained.

However, when these heat-sensitive recording materials are stored in a vinyl chloride bag or come into contact with a vinyl chloride desk mat, or when the heat-sensitive recording material is touched by hand, the vinyl chloride is not There is a drawback that the coloring portion is erased by the contained plasticizer and sebum.

When these heat-sensitive recording materials are exposed to sunlight or lighting for a long time, not only the printed part (coloring part) is blurred or disappears but also the background part is discolored (yellowing). It has the drawback of being erased, and when a facsimile-received paper, a word processor, a personal computer, etc., that is printed out and left on a desk, the recorded image becomes unclear, which is a problem in terms of document storage.

Among the above-mentioned color developers, bisphenol S is known to be relatively excellent in oil resistance. For example, JP-A-57-11088 and JP-A-58-11989 are known.
No. 3, JP-A-61-160292 and the like propose that the addition of bisphenol S improves the stability of the color image with respect to the plasticizer or the stability of the background portion. However, since bisphenol S has a high melting point and poor compatibility with the color forming layer, it has a drawback that the color density is low. Thus, concomitant agents for improving the color forming property of wax and the like have been investigated, but the color developing property is poor. It was still unsatisfactory in that it was sufficient and the oil resistance, which is the characteristic feature of bisphenol S, was reduced.

Further, Japanese Patent Publication No. 57-16914 proposes to use acetoacetic acid anilide as a sensitizer, but in combination with a general phenol developer such as bisphenol A, It lacked oil resistance and light resistance, and was not satisfactory in practical use.

Accordingly, it is an object of the present invention to provide a heat-sensitive recording material which has a good initial color density, little decoloring of the color part due to a plasticizer or the like, and excellent storage stability.

[0009]

Means for Solving the Problems As a result of intensive investigations by the present inventors, a heat-sensitive recording material containing a specific acylacetic acid anilide derivative together with bisphenol S in the heat-sensitive recording layer achieved the above object. It was found that it could be done.

The present invention has been made based on the above findings, and is represented by bisphenol S in the heat-sensitive recording layer and the following general formula (I) (Chemical formula 1). It is intended to provide a heat-sensitive recording material containing at least one kind of acylacetic acid anilide derivative.

[0011]

Embedded image

The thermal recording material of the present invention will be described in detail below.

The bisphenol S [bis (4-hydroxyphenyl) sulfone] used in the present invention has a color developing property by itself and has a function as a color developing agent.

The content of the bisphenol S is not particularly limited as it varies depending on the required performance and recording suitability, the type and amount of the color forming dye described below or other additives used in combination. Usually, it is 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, relative to 1 part by weight of the color forming dye. The above content is a color forming dye 1.
When the amount is less than 0.01 parts by weight, the color density is low, and when the amount is more than 10 parts by weight, the effect is not further increased and it is uneconomical.

The acylacetic acid anilide derivative represented by the above general formula (I) used in the present invention has a function as a sensitizer. In the acylacylanilide derivative, the alkyl group having 1 to 8 carbon atoms represented by R _{1 to} R ₄ in the general formula (I) includes methyl, ethyl,
Propyl, isopropyl, butyl, secondary butyl, tertiary butyl, isobutyl, amyl, tertiary amyl, hexyl, heptyl, octyl, isooctyl, tertiary octyl, 2-
Examples thereof include groups such as ethylhexyl, and examples of the alkoxy group having 1 to 8 carbon atoms represented by R _{2 to} R ₄ include the alkoxy groups derived from the above alkyl groups and represented by R _{2 to} R _4. As a halogen atom, a chlorine atom, a bromine atom,
Fluorine atoms are mentioned, and the number of carbon atoms represented by R ₁ is 6 to ₁
Examples of the aryl group or alkylaryl group of 8 include groups such as phenyl, naphthyl, 3-methylphenyl, 4-methylphenyl, 4-tertiarybutylphenyl, and 2,4-dimethylphenyl, and in particular, R ₁ is The effect is remarkable when an acetoacetic acid anilide derivative which is a methyl group is used.

Therefore, as specific representative examples of the acylacetic acid anilide derivative represented by the above general formula (I), compound No. 1 to compound No. 8 shown in the following [Chemical formula 3] to [Chemical formula 10], etc. Can be given.

[0017]

[Chemical 3]

[0018]

[Chemical 4]

[0019]

[Chemical 5]

[0020]

[Chemical 6]

[0021]

[Chemical 7]

[0022]

Embedded image

[0023]

[Chemical 9]

[0024]

[Chemical 10]

The content of the acylacetic acid anilide derivative varies depending on the content of the bisphenol S, the required performance and recording suitability, the type and the amount of the color forming dye or other additive used in combination, and therefore, in particular, Although not limited, the above bisphenol S1 is usually used.
0.1-5 parts by weight, preferably 0.2-
3 parts by weight are used. When the content is less than 0.1 parts by weight, the color developing sensitivity becomes insufficient, and even when it exceeds 5 parts by weight, the effect is not further increased and it is uneconomical.

The heat-sensitive recording material of the present invention comprises a heat-sensitive recording layer and a support, and the bisphenol S and at least one of the acetoacetic anilide derivative represented by the general formula (I) are contained in the heat-sensitive recording layer. It is contained. The heat-sensitive recording layer is composed of the bisphenol S.
And an acetoacetic acid anilide derivative represented by the general formula (I) and a color-forming substance, and if necessary, other developer, other sensitizer, known storage stabilizer, etc. Can be added to form.

The above-mentioned color-forming substance is usually a colorless or light-colored color-forming substance, and various dyes (color-forming dyes) are used as the color-forming substance. There is no particular limitation as long as it is used for.

Specific examples of the above-mentioned color forming dye include (1) 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide and 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)-
Triarylmethane compounds such as 5-dimethylaminophthalide and 3,3-bis (2-phenyl-3-indolyl) -5-dimethylaminophthalide; (2) 4,4-bis (dimethylamino) benzhydride Diphenylmethane compounds such as phosphorus benzyl ether and N-2,4,5-trichlorophenylleuco auramine; (3) Rhodamine-β-anilinolactam, 3- (N-methyl-N-cyclohexylamino) -6-methyl -7-anilinofluorane, 3-diethylamino-7-octylaminofluorane, 3-diethylamino-7- (2-chloroanilino) fluorane, 3-diethylamino-6-methyl-7
-Anilinofluorane, 3-diethylamino-6-methyl-7- (2,4-dimethylanilino) fluorane, 3
-Diethylamino-7-dibenzylaminofluorane,
3-diethylamino-6-chloro-7- (β-ethoxyethylamino) fluorane, 3-diethylamino-6-
Chloro-7- (γ-chloropropylamino) fluorane, 3- (N-ethyl-N-isoamylamino) -6-
Methyl-7-anilinofluorane, 3- (N-ethyl-
N-ethoxyethylamino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane, 3- (N-ethyl) -N-tolylamino) -6-methyl-7-anilinofluorane, 3-N, N-dibutylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-7- (2-chloroanilino) fluorane ,
3-dipentylamino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3- (4-anilino) anilino-6-methyl-7-chlorofluorane, etc. Xanthene compound of
(4) Thiazine-based compounds such as benzoyl leuco methylene blue and p-nitrobenzoyl leuco methylene blue; (5) 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-methylnaphtho- Spiro compounds such as (3-methoxybenzo) spiropyran; (6) Other 3,
5 ', 6-tris (dimethylamino) -spiro [9H-
Fluorene-9,1 '(3'H) -isobenzofuran]
-3'-one, 1,1-bis [2- (4-dimethylaminophenyl) -2- (4-methoxyphenyl) ethenyl] -4,5,6,7-tetrachloro (3H) isobenzofuran-3 -ON, etc., and these dyes can be used alone or in combination of two or more.

Further, as described above, the bisphenol S used in the present invention has an effect as a developer by itself, so that it is not necessary to use another developer.
When it is necessary to increase the color-developing sensitivity, a well-known developer such as a phenol type, an organic carboxylic acid type or a metal salt type can be used in combination. Further, the content of the bisphenol S in the present invention can be reduced by using these other color developers in combination.

Examples of the other color developer include p-octylphenol, p-tert-butylphenol, p-phenylphenol, p-hydroxyacetophenone and α.
-Naphthol, β-naphthol, p-tertiary octylcatechol, 2,2'-dihydroxybiphenyl, bisphenol-A, 1,1-bis (p-hydroxyphenyl)
Butane, 2,2-bis (4-hydroxyphenyl) heptane, 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, bis (3-allyl-4-hydroxyphenyl) sulfone, bis (3,4-dihydroxyphenyl) sulfone, 2,4'-dihydroxydiphenyl sulfone, 1,
1-bis (4-hydroxyphenyl) cyclohexane,
Bis (4-hydroxyphenyl) ether, bis [2-
(4-Hydroxyphenylthio) ethoxy] methane, 4
-(4-Isopropoxybenzenesulfonyl) phenol, dimethyl 4-hydroxyphthalate, butyl bis (4-hydroxyphenyl) acetate, benzyl p-hydroxybenzoate, phenolic such as 3,5-di-tert-butylsalicylic acid, benzoin Examples include organic carboxylic acid-based developers such as acids and metal salt-based developers such as zinc salicylate. Of these, phenol-based developers are particularly preferably used.

The amount of the other color developer used is usually 0.1 to 10 parts by weight, preferably 0.2 to 5 parts by weight, based on 1 part by weight of the color forming dye. When the amount used is less than 0.1 parts by weight with respect to 1 part by weight of the color forming dye, the color developing sensitivity is insufficient, and even when it exceeds 10 parts by weight, the effect is further increased. It is uneconomical.

Further, since the above-mentioned acylacetic acid anilide derivative is a sensitizer, it is not necessary to use other sensitizers. However, in the heat-sensitive recording material of the present invention, in order to enhance its color developing sensitivity, other It is also possible to use together with a sensitizer of, for example, zinc acetate, zinc octylate, zinc laurate, zinc stearate, zinc oleate, zinc behenate, zinc benzoate, zinc dodecyl salicylate, calcium stearate. , Metal salts of organic acids such as magnesium stearate, aluminum stearate; stearic acid amide, stearic acid methylol amide, stearoyl urea, acetanilide, acetotoluidide, benzoic acid stearyl amide, ethylene bis stearic acid amide, hexamethylene bis octyl acid amide, etc. Amide compound; 1,2-bis 3,4-dimethylphenyl) ethane, m- terphenyl, 1,2-diphenoxyethane, 1,2-bis (3-methylphenoxy) ethane, p
-Benzylbiphenyl, p-benzyloxybiphenyl,
Diphenyl carbonate, bis (4-methylphenyl)
Carbonate, dibenzyl oxalate, bis (4-methylbenzyl) oxalate, 1-hydroxy-2-naphthalenecarboxylic acid phenyl, 1-hydroxy-2-naphthalenecarboxylic acid benzyl, 3-hydroxy-2-naphthalenecarboxylic acid phenyl, Methylenedibenzoate, 1,4-bis (2-vinyloxyethoxy) benzene, 2-benzyloxynaphthalene, benzyl 4-benzyloxybenzoate, dimethyl phthalate, dibenzyl terephthalate, dibenzoylmethane, 4-methylphenoxy-p-biphenyl Etc., and these sensitizers are usually used in an amount of 0.1 to 1 with respect to 1 part by weight of the color forming dye.
0 parts by weight are used.

Further, in the heat-sensitive recording material of the present invention, when a particularly high storage stability is required, a known storage stabilizer can be used in combination, if necessary.

Examples of the storage stabilizer include 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'-thiobis (6-tert-butyl-4-methylphenol),
Hindered phenol compounds such as 2,2′-methylenebis (6-tert-butyl-4-methylphenol), 4-
Benzyloxy-4 ′-(2-methylglycidyloxy) diphenylsulfone, sodium-2,2′-methylenebis (4,6-ditertiarybutylphenyl) phosphate and the like can be mentioned. These storage stabilizers are usually 0.1 to 10 parts by weight is used for 1 part by weight of the color forming dye.

The heat-sensitive recording material of the present invention can be obtained, for example, as follows. A dispersion liquid of the bisphenol S used in the present invention and the acylacetic acid anilide derivative represented by the general formula (I) is prepared. The dispersions may be prepared separately, mixed together, or may be mixed together, or may be mixed and melted to prepare a dispersion. In addition to the above dispersion liquid, a color-forming dye (color-forming colorless dye), other color-developing agents and other sensitizers used as necessary, a storage stabilizer, etc. are usually used in a ball mill, an attritor, a sand grinder, etc. The heat-sensitive recording of the present invention, which is atomized by a grinder or an appropriate emulsifying device, is added with various additive materials according to the purpose to prepare a coating liquid, and the coating liquid is applied to paper or various films. The material can be obtained.

The above-mentioned coating liquid is usually polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose,
Polyvinylpyrrolidone, polyacrylamide polymer, starches, styrene-maleic anhydride copolymer, vinyl acetate-maleic anhydride copolymer, styrene-butadiene copolymer or a binder such as a modified product thereof, kaolin,
Fillers such as silica, diatomaceous earth, talc, titanium dioxide, calcium carbonate, magnesium silicate, magnesium carbonate, aluminum hydroxide and melamine are mixed, but in addition to these, metallic soaps, amides, waxes, light stabilizers. A water resistant agent, a dispersant, an antifoaming agent, etc. can be added as necessary.

The heat-sensitive recording material of the present invention can be used in various applications such as facsimile paper, printer paper, label, price tag, ticket, etc. to which the heat-sensitive recording material is applied.

[0038]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these examples.

Example 1 and Comparative Example 1 20 g of 3- (N, N-dibutylamino) -6-methyl-7-anilinofluorane and 100 g of a 10% aqueous polyvinyl alcohol solution were thoroughly ground with a ball mill to prepare a dispersion liquid. It was set to A.

Dispersion B was obtained by thoroughly grinding 20 g of bisphenol S together with 100 g of a 10% aqueous solution of polyvinyl alcohol in a ball mill.

20 g of sample compound (shown in [Table 1] below)
Was thoroughly ground in a ball mill together with 100 g of a 10% aqueous polyvinyl alcohol solution to obtain a dispersion C.

The above dispersions A, B and C were mixed in a weight ratio of 1: 2: 2, 50 g of calcium carbonate was added to 200 g of the mixed solution, and the mixture was sufficiently dispersed to obtain a coating solution. A 32 μm-thick coating was applied on a base paper of / m ² and dried to obtain a heat-sensitive recording material.

Using the obtained heat-sensitive recording material, a heat-sensitive printing device (TH-PMD: made by Okura Electric Co., Ltd.) was used to print with a pulse width of 0.8 msec. The density (initial density) was measured with a Macbeth densitometer (Model RD-933 manufactured by Macbeth Co.).

The color-developed heat-sensitive recording material was stored for 24 hours at 60 ° C. under a dry condition, and the densities of the printed part and the background part were measured to evaluate the heat-resistant storage stability.

Further, the color-developed heat-sensitive recording material was placed in a carbon arc fade meter, and the density of the printed portion and the background portion after irradiation for 6 hours was measured to evaluate the light resistance storage stability. In addition, the density of the background portion was measured using a yellow filter.

Further, a vinyl chloride resin film plasticized with dioctyl phthalate was adhered to the colored thermosensitive recording material at room temperature for 24 hours, and the density was measured.
The oil storage stability was evaluated.

The results are shown in Table 1 below.

[0048]

[Table 1]

In the above [Table 1], compound No. 1 to compound
No. 8 shows the compounds of [Chemical Formula 3] to [Chemical Formula 10] (hereinafter the same), and * 1 to * 3 are as follows.

[0050]

[Chemical 11]

[0051]

[Chemical 12]

[0052]

[Chemical 13]

Example 2 20 g of 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluorane and 100 g of a 10% aqueous polyvinyl alcohol solution were thoroughly ground with a ball mill to obtain dispersion A. Obtained.

20 g of bisphenol S and 100 g of a 10% aqueous polyvinyl alcohol solution were thoroughly ground with a ball mill to obtain a dispersion B.

20 g of sample compound (shown in [Table 2] below)
Was thoroughly ground in a ball mill together with 100 g of a 10% aqueous polyvinyl alcohol solution to obtain a dispersion C.

The above dispersions A, B and C were mixed in a weight ratio of 1:
Mix at a ratio of 2: 2, disperse well to give a coating solution, and apply this coating solution on a base paper of 50 g / m ^{2 in} a thickness of 32 μm,
It was dried to obtain a heat sensitive recording material.

Comparative Example 2 A thermosensitive recording material was obtained in the same manner as in Example 2 except that bisphenol A was used instead of bisphenol S used in Dispersion B of Example 2.

The same test as in Example 1 was conducted using the obtained heat-sensitive recording material. The results are shown in [Table 2] below.

[0059]

[Table 2]

From the results of the above [Table 1] and [Table 2], the following is clear. When bisphenol S was used as a color developer and a sensitizer other than acylacetic acid anilide was used (Comparative Examples 1-1 to 1-3), the color development sensitivity was low, and practical color development was not expected. When S is replaced with bisphenol A (Comparative Examples 2-1 to 2-3), the color development sensitivity is improved, but the oil resistance is deteriorated.

On the other hand, when the bisphenol S according to the present invention and the acylacetic acid anilide derivative represented by the general formula (I) are used in combination (Examples 1-1 to 1-
8), 2-1 to 2-3) not only have good initial color density, but also have excellent oil resistance, and even after the storage test, there is very little decoloring of the colored part (printed part) and background fog.

[0062]

INDUSTRIAL APPLICABILITY The heat-sensitive recording material of the present invention, by containing bisphenol S and a specific acylacetic acid anilide derivative, has a good initial color density, little decoloring of the color part by a plasticizer, and storage stability. It has excellent properties.

Claims (2)

[Claims] 1. The heat-sensitive recording layer contains at least one of bis (4-hydroxyphenyl) sulfone and an acylacetic acid anilide derivative represented by the following general formula (I). Heat sensitive recording material Embedded image 2. The heat-sensitive recording material according to claim 1, wherein the acylacetic acid anilide derivative is an acetoacetic acid anilide derivative.