JP2002225439A - Heat-sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-sensitive recording material devised to improve sensitivity of a heat-sensitive sheet by using a developer having a high thermal sensitivity. SOLUTION: The heat-sensitive recording material comprises at least a leuco dye and a developer of the leuco dye. As the developer, 4,4'-dihydroxy-3,3',5,5'- tetramethyldiphenyl-methane is blended.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heat-sensitive recording material, and more particularly, to a heat-sensitive recording material excellent in high-speed recording.

[0002]

2. Description of the Related Art A thermosensitive recording paper having a structure in which a thermosensitive recording material containing at least a leuco dye and a developer of the leuco dye is provided on a support has been known. In particular, bisphenol A (melting point: 157) is used as the developer.
C.) is preferably used (JP-A-56-15394).
JP-A-57-151394, JP-A-57-151394
-152784, JP-A-3-120088).

[0003] In recent years, it has been found that bisphenol A has a problem of an environmental hormone, and switching to another developer has been studied. And, bisphenol S has attracted attention as a substitute. However, bisphenol S has a high melting point (250 ° C.), low color development sensitivity to ripening, and is unsuitable for high-speed recording. Therefore, fatty acid amide or the like may be used as a sensitizer conventionally used, but the effect of lowering the melting point is not sufficient.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to improve the sensitivity of thermal paper by using a developer having high thermal sensitivity. An object of the present invention is to provide a heat-sensitive recording material.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventor has found that the above objects can be easily achieved by using a specific compound, and has completed the present invention. .

That is, the gist of the present invention is to provide a thermosensitive recording material containing at least a leuco dye and a developer of the leuco dye as 4,4'-dihydroxy-3,3 ', 5,5' as a developer. -A thermosensitive recording material characterized by comprising tetramethyldiphenylmethane.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the first invention, the heat-sensitive recording material contains at least a leuco dye and 4,4'-dihydroxy-3,3 ', 5,5'-tetramethyldiphenylmethane as a developer for the leuco dye. Then, if necessary, similarly to conventionally known heat-sensitive recording materials, additives such as a binder, a pigment, a lubricant, a sensitizer, a wax, a dispersant, and an antifoaming agent are contained. The second invention further provides 4,4'-dihydroxy- as a color developer.
3,3 ', 5,5'-tetramethyldiphenylmethane and bisphenol S are used in combination.

[0008] Leuco dyes include, for example, crystal violet lactone, malachite green lactone,
3-diethylamino-7-methylfluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3-
Diethylamino-7-benzylaminofluoran, 3-
Diethylamino-7-anilinofluoran, 3- (N-
Methylanilino) -7-anilinofluoran, 3-diethylamino-7- (m-trifluoromethylanilino)
Fluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3- (N-methylcyclohexylamino) -6-methyl-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-anilino Fluoran, 3-
Piperidino-6-methyl-7-anilinofluoran, 3
-(N-methyl-p-toluidino) -6-methyl-7-
Anilinofluoran, benzo-β-naphthospiropyran and the like can be mentioned.

As the binder, for example, polyvinyl alcohol, starch and derivatives thereof, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylic acid ester Water solubility of polymers, acrylamide / acrylic acid ester / methacrylic acid copolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, etc. In addition to the polymer,
Emulsions such as polyurethane, polyacrylate, polymethacrylate, vinyl chloride / vinyl acetate copolymer and ethylene / vinyl acetate copolymer, and latexes such as styrene / butadiene copolymer.

Examples of the pigment include kaolin, calcined kaolin, talc, fluorite, diatomaceous earth, calcium carbonate, aluminum hydroxide, magnesium hydroxide, magnesia, titanium oxide, barium carbonate and the like.

[0011] Lubricants are used for the purpose of preventing head abrasion and sticking, and specific examples thereof include higher fatty acid metal salts such as zinc stearate and calcium stearate, paraffin, paraffin oxide, polyethylene, polyethylene oxide, and stearin. And waxes such as acid amide and caster wax.

Examples of the sensitizer include terephthalic acid ester, terephenyl, tribenzylamine, benzylmandenoic acid, parabenzylbiphenyl and di-adipate.
o-Chlorobenzyl, dibenzyl oxalate, di-p-chlorobenzyl oxalate, phenyl 1-hydroxy-2-naphthoate, 1,2-di- (3-methylphenoxy) ethane and the like.

Examples of the waxes include stearic acid amide, palmitic acid amide, oleic acid amide, lauric acid amide, ethylenebisstearamide, methylenebisstearamide, and methylol stearamide. As a dispersant, for example,
Sodium dioctyl sulfosuccinate and the like can be mentioned, and examples of the defoaming agent include various defoaming agents of silicone type, fluorine type and acrylate ester type.

In the present invention, in addition to the above components, other known coloring materials may be used together with bisphenol S.

As a developer other than bisphenol S,
4,4′-isopropylidenebisphenol, 3,4 ′
-Isopropylidenebisphenol, 4,4, -isopropylidenebis (o-methylphenol), 4,4'-
sec butylidenebisphenol, 4,4'-isopropylidenebis (otbutylphenol), 4,4,-
Cyclohexylidene diphenol, 4,4′-isopropylidenebis (2-chlorophenol), 2,2′-methylenebis (4-methyl-6-tbutylphenol),
2,2'-methylenebis (4-ethyl-6-tbutylphenol), 4,4'-butylidenebis (6-tbutylphenol-2-methyl) phenol, 1,1,3-tris (2-methyl-4-hydroxy-5- t-butylphenyl) butane, 1,1,3-tris (2-methyl-4-
(Hydroxy-5-cyclohexylphenyl) butane,
4,4'-thiobis (6-tbutyl-2-methyl) phenol, 4,2'-diphenolsulfone, 4-isopropoxy-4, -hydroxydiphenylsulfone, 4-
Benzyloxy-4′-hydroxydiphenyl sulfone,
4,4′-diphenol sulfoxide, isopropyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, benzyl protocatechuate, stearyl gallate,
Lauryl gallate, octyl gallate, 1,7-bis (4-hydroxyphenylthio) -3,5-dioxaheptane, 1,5-bis (4-hydroxyphenylthio)
-3-oxapentane, 1,3-bis (4-hydroxyphenylthio) -propane, N, N'-diphenylthiourea, N, N'-di (m-chlorophenyl) thiourea,
Salicylanilide, 5-chloro-salicylanilide, salicyl-O-chloroanilide, 2-hydroxy-3-naphthoic acid, antipyrine complex of zinc thiocyanate, 2-
Zinc salt of acetyloxy-3-naphthoic acid, 2-hydroxy-1-naphthoic acid, 1-hydroxy-2-naphthoic acid, metal salts of hydroxynaphthoic acid such as zinc, aluminum and calcium, bis (4-hydroxyphenyl) Acetic acid methyl ester, bis (4-hydroxyphenyl) acetic acid benzyl ester, 4- {β- (p-methoxyphenoxy) ethoxy} salicylic acid, 1,3-bis (4-hydroxycumyl) benzene, 1,4- Bis (4-hydroxycumyl) benzene and the like can be mentioned.

The proportions of the leuco dye, the developer, the binder, the pigment, the lubricant, the sensitizer, the dispersant, the defoamer and the wax are as follows:
Usually, the developer is 10 to 10 parts by weight of the leuco dye.
1000 parts by weight (preferably 50 to 700 parts by weight), the binder is 10 to 200 parts by weight (preferably 20 to 100 parts by weight), and the pigment is 50 to 400 parts by weight (preferably 100 to 100 parts by weight).
To 200 parts by weight), a lubricant is 10 to 100 parts by weight (preferably 20 to 50 parts by weight), a sensitizer is 10 to 800 parts by weight (preferably 20 to 400 parts by weight), and a wax is 10 to 100 parts by weight.
To 800 parts by weight (preferably 20 to 400 parts by weight), the dispersant 1 to 50 parts by weight (preferably 5 to 20 parts by weight),
0.001 to 0.5 parts by weight (preferably 0.0 to 0.5 parts by weight)
05 to 0.1 part by weight).

A feature of the present invention is that the heat-sensitive recording material as described above has a low melting point of 4,4'-dihydroxy-3,
The point is to use 3 ', 5,5'-tetramethyldiphenylmethane. Thereby, the sensitivity of the heat-sensitive recording material increases, and the recording speed increases. When used in combination with bisphenol S, 4,4′-dihydroxy-3,3 ′, 5,5
5'-Tetramethyldiphenylmethane lowers the melting point of bisphenol S and acts not only as a color developer but also as a sensitizer for the thermosensitive recording material.

4,4'-dihydroxy-3,3 ', 5
The method of blending 5′-tetramethyldiphenylmethane is not particularly limited. However, when used in combination with bisphenol S, (1) a method in which a pulverized product of a melt mixture with bisphenol S is blended with other components, (2) bisphenol S and 4,4′-dihydroxy-3,3 ′, 5,5 (3) bisphenol S and 4,4'-dihydroxy-3,3 ', 5,5'-tetramethyldiphenylmethane are previously mixed with a powder mixture of 5'-tetramethyldiphenylmethane and other components. It is possible to adopt a method of blending with other components without performing. Among them, the method (1) is preferable because the effect of lowering the melting point of bisphenol S is large.

The heat-sensitive recording material of the present invention is coated on a support and used for heat-sensitive recording in the same manner as conventionally known heat-sensitive recording.

[0020]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. In the following, in order to further clarify the effects of the present invention, the leuco dye and 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethyl were preceded by the examples of the thermosensitive recording material. A confirmation test of the color development starting temperature by mixing diphenylmethane and bisphenol S was performed. Table 1 shows various melting points and final melting points of each developer compound used.

[0021]

[Table 1]

Test Example 1 The leuco dyes 3-dimethylamino-6-methyl-7-anilinofluoran and 4,4'-hydroxy-3,3 ', 5
5′-Tetramethyldiphenylmethane was mixed at a weight ratio of 1 to 1, taken into a glass capillary, placed on a melting point measuring apparatus, and visually checked for a color development temperature while raising the temperature. Table 2 shows the results.

Test Example 2 The leuco dyes 3-dimethylamino-6-methyl-7-anilinofluoran and 4,4'-hydroxy-3,3 ', 5
5′-Tetramethyldiphenylmethane and bisphenol S were mixed at a weight ratio of 1: 0.75: 0.25, taken in a glass capillary, applied to a melting point measuring apparatus, and visually checked for the color development temperature while raising the temperature. Table 2 shows the results.

Test Example 3 The leuco dyes 3-dimethylamino-6-methyl-7-anilinofluoran and 4,4'-hydroxy-3,3 ', 5
5′-Tetramethyldiphenylmethane and bisphenol S were mixed at a weight ratio of 1: 0.50: 0.50, taken in a glass capillary, set on a melting point measuring apparatus, and visually examined for the color development temperature while raising the temperature. Table 2 shows the results.

Test Example 4 The leuco dyes 3-dibutylamino-6-methyl-7-anilinofluoran and 4,4'-hydroxy-3,3 ', 5,5'
-Tetramethyldiphenylmethane and bisphenol S were mixed at a weight ratio of 1: 0.25: 0.75, taken in a glass capillary, placed on a melting point measuring apparatus, and visually checked for the color development start temperature while raising the temperature. Table 2 shows the results.

Comparative Test Example 1 A leuco dye, 3-dibutylamino-6-methyl-7-anilinofluoran, and bisphenol S were mixed at a weight ratio of 1 to 1, taken in a glass capillary, and subjected to a melting point measuring apparatus.
While the temperature was being raised, the color development start temperature was visually examined. Table 2 shows the results
Shown in

Test Example 5 The leuco dyes 3-dibutylamino-6-methyl-7-anilinofluoran and 4,4'-hydroxy-3,3 ', 5
5′-Tetramethyldiphenylmethane and bisphenol S were mixed at a weight ratio of 1: 0.50: 0.50, taken in a glass capillary, placed on a melting point measuring device, and visually checked for the color development temperature while raising the temperature. However, 4,4'-hydroxy-3,3 ', 5,5'-tetramethyldiphenylmethane and bisphenol S were used by previously heating, melting, mixing and pulverizing. Table 2 shows the results.

[0028]

[Table 2]

Example 1 Leuco dye and 4,4'-dihydroxy-3,3 ', 5
A thermal recording paper was prototyped using 5'-tetramethyldiphenylmethane, and a printing test was performed. The details will be described below.

The liquids A and B shown in Table 3 below were separately pulverized and dispersed in a ball mill for 48 hours, and then mixed at a weight ratio of 1: 2 to obtain a coating liquid for thermal recording. This coating solution was applied to the surface of high quality paper so that the dry coating amount was 5 g / m ² , and then dried to obtain a thermosensitive recording paper.

[0031]

[Table 3]

The obtained heat-sensitive recording paper was colored by facsimile, and the print density was evaluated by visual comparison. The evaluation criteria were as follows: ○: high blackness and sharp, ×: low blackness and unclear. Table 4 shows the results.

Example 2 In Example 1, 4,4'-dihydroxy-3,3 ',
1 part by weight of 0.25 to 0.75 mixture of 4,4'-dihydroxy-3,3 ', 5,5'-tetramethyldiphenylmethane and bisphenol S instead of 5,5'-tetramethyldiphenylmethane A thermal paper was obtained in the same manner except for using the thermal paper.

Example 3 In Example 1, 4,4'-dihydroxy-3,3 ',
1 part by weight of a mixture of 4,4'-dihydroxy-3,3 ', 5,5'-tetramethyldiphenylmethane and bisphenol S in a ratio of 0.50 to 0.50 instead of 5,5'-tetramethyldiphenylmethane A thermal paper was obtained in the same manner except for using the thermal paper.

Example 4 In Example 1, 4,4'-dihydroxy-3,3 ',
1 part by weight of a mixture of 4,4'-dihydroxy-3,3 ', 5,5'-tetramethyldiphenylmethane and bisphenol S in a ratio of 0.25 to 0.75 instead of 5,5'-tetramethyldiphenylmethane A thermal paper was obtained in the same manner except for using the thermal paper.

Example 5 In Example 1, 4,4'-dihydroxy-3,3 ',
4, in place of 5,5′-tetramethyldiphenylmethane,
0.5 to 0.5 of 4'-dihydroxy-3,3 ', 5,5'-tetramethyldiphenylmethane and bisphenol S
And a heat-sensitive paper was obtained in the same manner except that 1 part by weight of the mixture was used.

Comparative Example 1 In Example 1, 4,4'-dihydroxy-3,3 ',
A thermosensitive paper was obtained in the same manner except that bisphenol S was used in place of 5,5'-tetramethyldiphenylmethane and 1 part by weight of bisphenol S.

[0038]

[Table 4]

[0039]

According to the present invention described above, the thermal sensitivity of the developer can be greatly reduced, and high-speed printing on thermal paper can be performed.

Continued on the front page (72) Inventor Takashi Watanabe 34-ka Takayama, Onahama, Iwaki-shi, Fukushima Japan Kasei Co., Ltd. Reference) 2H026 AA07 BB02 BB30 BB39

Claims (2)

[Claims] 1. A thermosensitive recording material containing at least a leuco dye and a developer of said leuco dye, wherein 4,4'-dihydroxy-3,3 ', 5,5'-tetramethyldiphenylmethane is blended as a developer. A heat-sensitive recording material characterized by comprising: 2. As a color developer, 4,4′-dihydroxy-
The heat-sensitive recording material according to claim 1, wherein 3,3 ', 5,5'-tetramethyldiphenylmethane and bisphenol S are blended.