JP2665683B2 - Thermal recording material - Google Patents

Description

Description: 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 having excellent storage stability of a color image.

2. Description of the Related Art A heat-generating recording material using a colorless or pale-colored color-forming substance and a color-developing substance capable of coloring the color-forming substance when heated is disclosed in
No. -4160 and Japanese Patent Publication No. 45-14039, which are widely used. In general, a thermosensitive recording material is obtained by separately dispersing a developer such as a leuco dye and a phenolic substance into fine particles, and then mixing the two, and adding additives such as a binder, a sensitizer, a filler, and a lubricant. As a coating liquid, coated on a support such as paper, film, or synthetic paper, and heated to obtain a color record by a chemical reaction caused by the melting or contact of one or both of the leuco dye and the developer. A sheet-like thermosensitive recording material is usually prepared. A thermal printer with a built-in thermal head or the like is used for coloring the heat-sensitive recording sheet. In this thermal recording method, (1) no noise is generated at the time of recording as compared with other recording methods. (2) No need for development and fixing, etc. (3) Maintenance-free, (4) Machines are relatively inexpensive, etc., so that they are used for facsimile, computer output, printers such as calculators, and medical measurement Are widely used in the field of recorders, automatic ticket vending machines, heat-sensitive recording labels, and the like.

Among these fields of use, the use of labels and station automation systems for tickets is increasing due to the expansion of POS systems in retail stores and supermarkets. A problem in these applications is that the color image disappears or fades due to a plasticizer or the like. Conventionally, various methods have been proposed for improving the plasticizer resistance of a color image, but a satisfactory method has not yet been established.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned disadvantages of the prior art. That is, it is an object of the present invention to provide a heat-sensitive recording material having good so-called plasticizer resistance, in which decoloration and fading of a color image are not caused by a plasticizer or the like.

Means for Solving the Problems The present inventors have made various studies to achieve the above object, and as a result, completed the present invention. That is, the present invention relates to a thermosensitive recording material in which a colorless or pale-colored color-forming substance and a heat-sensitive color-forming layer mainly composed of a color-developing substance capable of coloring the color-forming substance when heated are formed on a support. And a triazine-based compound represented by the following formula (I):

[In formula (I), R ₁ , R ₂ and R ₃ represent hydrogen, alkyl having 1 to 5 carbon atoms, alkoxy, halogen or aralkyl having 1 to 5 carbon atoms, and X represents oxygen or sulfur. The present invention will be described in detail.

The heat-sensitive recording material of the present invention comprises the triazine-based compound of the formula (I) and a color-forming substance, a color-developing substance, and, if necessary, a filler containing a heat-fusible compound and a surfactant, and the like. It is obtained by containing it in a layer.

The triazine compounds of the formula (I) used in the present invention include 2,4,6-trisphenoxy-S-triazine, 2,4,6-tris (1-methylphenoxy) -S-triazine, and 2,4 , 6-Tris (2,6-dimethylphenoxy)
-S-triazine, 2,4,6-tris (2,4,5-trimethylphenoxy) -S-triazine, 2,4,6-tris (2-
(Butylphenoxy) -S-triazine, 2,4,6-tris (2-methoxyphenoxy) -S-triazine, 2,4,6
-Tris (4-butoxyphenoxy) -S-triazine, 2,4,6-tris (2-dichlorophenoxy) -S-
Triazine, 2,4,6-tris (4-bromophenoxy)
-S-triazine, 2,4,6-tris (3,4-dichlorophenoxy) -S-triazine, 2,4,6-tris (benzyloxy) -S-triazine, 2,4,6-tris (2 -Methylbenzyloxy) -S-triazine, 2,4,6-tris (phenylthio) -S-triazine, 2,4,6-tris (1-methylphenylthio) -S-triazine, 2,4,6
-Tris (3,4-dimethylphenylthio) -S-triazine, 2,4,6-tris (2-methoxyphenylthio)-
S-triazine, 2,4,6-tris (4-butoxyphenylthio) -S-triazine, 2,4,6-tris (2-chlorophenylthio) -S-triazine, 2,4,6-tris (2,4-Dibromophenylthio) -S-triazine and the like are used. The preferred use amount is 1 to 15% by weight, more preferably 5 to 10% by weight, based on the total weight of the heat-sensitive recording color-forming layer. Examples of the coloring substance include xanthene compounds, triarylmethane compounds, spiropyran compounds, diphenylmethane compounds, thiazine compounds, and fluorene compounds. Specific examples thereof are given below.

2-anilino-3-methyl-6-diethylaminofluoran and 2-anilino-3 as xanthene compounds
-Methyl-6- (methylcyclohexylamino) -fluoran, 2-anilyl-3-methyl-6- (ethylisobentylamino) fluoran, 2-anilino-3-methyl-6-dibutylaminofluoran, 2- ( p-chloroanilino) -3-methyl-6-diethylaminofluoran, 2- (p-fluoroanilino) -3-methyl-6-
Diethylaminofluoran, 2-anilino-3-methyl-6- (p-triidinoethylamino) fluoran, 2
-(P-toluidino) -3-methyl-6-diethylaminofluoran, 2- (o-chloroanilino) -6-dibutylaminofluoran, 2- (o-fluoroanilino)
-6-diethylaminofluoran, 2- (o-fluoroanilino) -6-dibutylaminofluoran, 2-anilino-3-methyl-6-piperidinofluoran, 2-anilino-3-methyl-6 Pyrrolidinofluoran, 2-
Ethoxyethylamino-3-chloro-6-diethylaminofluoran, 2-anilino-3-chloro-6-diethylaminofluoran, 2-chloro-6-diethylaminofluoran, 2-methyl-6-diethylaminofluoran and the like; 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone) as a reel methane compound;
3,3-bis- (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2
-Dimethylaminoindol-3-yl) phthalide and the like;
Diphenylmethane compounds such as 3-methyl-3-spirodinaphthopyran and 1,3,3-trimethyl-6'-nitro-8'-methoxyspiro (indoline-2,2'-benzopyran) as spiropyran compounds; N-halophenyl-leuco auramine, benzoyl leucomethylene blue as a thiazo compound, 3,6-bis (dimethylamino) fluorene spiro (9,3 ')-6'-dimethylaminophthalide as a fluorene compound [3 , 6
-Bis (dimethylamino) fluorenespiro (9,3 ')
-6'-pyrrolidinophthalide], [3-dimethylamino-6-dieramino-fluorenespiro (9,3 ')-
6'-pyrrolidinophthalide], and these leuco dyes are used alone or in combination.

Examples of the color-developing substances include p-octylphenol and p-octylphenol.
tert-butylphenol, p-phenylphenol, 1,
1-bis (p-hydroxyphenyl) propane, 2,2-bis (p-hydroxyphenyl) -propane, 1,1-bis (p-hydroxyphenyl) cyclohexane, 4,4'-
Thiobisphenol, 4,4'-sulfonyldiphenol, bis- (3-allyl-4-hydroxyphenyl)-
Sulfone, novolak type phenol resin, benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate,
Dimethyl 4-hydroxyphthalate, ethyl 5-hydroxyisophthalate, 3,5-di-tert-butylsalicylic acid,
Examples of 3,5-di-α-methylbenzylsalicylic acid and the like and aromatic carboxylic acids include polyvalent metal salts thereof.

As a binder, methylcellulose, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetylated polyvinyl alcohol, silica-modified polyvinyl alcohol, alkali salts of styrene acrylate copolymer, polyvinylpyrrolidone, Polyacrylamide, polyacrylic acid, starch and its derivatives, casein, gelatin, styrene
Water-soluble ones such as an alkali salt of a maleic anhydride copolymer, an alkali salt of an iso (or diiso) butylene-maleic anhydride copolymer, or polyvinyl acetate, a vinyl chloride / vinyl acetate copolymer, polystyrene, and polyacryl Water-insoluble emulsions such as acid esters, polyurethanes, and styrene / butadiene / acrylic acid copolymers are used.

Calcium carbonate, magnesium carbonate,
Examples include magnesium oxide, silica, white turbon, talc, clay, alumina, magnesium hydroxide, aluminum hydroxide, aluminum oxide, barium sulfate, polystyrene resin, and urea-formalin resin.

Examples of the heat-fusible compound include waxes such as animal and vegetable waxes, polyethylene waxes, and synthetic waxes, higher fatty acids, higher fatty acid amides, higher fatty acid metal salts, acetylated aromatic amines, aromatic ether compounds, and biphenyl derivatives. And a solid having a melting point of 80 ° C. or higher.

As other additives, lubricants such as zinc stearate, calcium stearate and aluminum stearate, various surfactants, antifoaming agents and the like are added as required.

The heat-sensitive recording material of the present invention can be obtained by using the above-mentioned material, for example, by the following method.

That is, first, the color-forming substance, the color-developing substance and the formula (I)
A triazine compound, and if necessary, a heat-fusible compound,
After each of the other additives is separately dispersed with a binder, water or an organic solvent in a dispersing machine such as a ball mill, an attritor, or a sand mill (the triazine-based compound of the formula (I) may be a color-forming substance or (They may be mixed in advance with the color-developing substance and dispersed at the same time.) The mixture is mixed to prepare a thermosensitive coloring layer-forming coating solution, and the paper, plastic sheet,
It is applied on a support such as synthetic paper at 5 to 40 g / m ² by a bar coater or the like and dried to obtain the heat-sensitive recording material of the present invention. (The ratio of the coloring substance to the developing substance is usually the dry weight ratio.
(1: 1 to 1:10) Further, if necessary, an intermediate layer may be provided between the support and the thermosensitive coloring layer, or an overcoat layer may be provided on the thermosensitive coloring layer.

The color image of the heat-sensitive recording sheet of the present invention in which the triazine-based compound of the formula (I) is contained in the heat-sensitive recording color-forming layer,
By the action of the triazine compound of the formula (I), the decolorizing action of the plasticizer is inhibited, and good plasticizer resistance is exhibited.

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. `` Parts '' in the examples
Indicates parts by weight.

Example 1. Liquids (A) to (D) were prepared by separately pulverizing and dispersing a mixture having the following compositions using a sand grinder so that the average particle diameter was 2 μm or less.

Next, solution (A): solution (B): solution (C): solution (D) was added to 6:
Prepare a thermosensitive coloring layer forming solution by mixing at a ratio of 34:40:20,
The heat-sensitive recording sheet of the present invention was obtained by applying and drying a dry solid content of 10 g / m ² on the surface of high quality paper weighing about 50 g / m ² .

Example 2. Except that 2,4,6-trisphenoxy-S-triazine was used in place of 2,4,6-tris (2,6-dimethylphenoxy) -S-triazine used in Example 1. Example 1
In the same manner as in the above, a heat-sensitive recording sheet of the present invention was obtained.

Example 3 2,4,6-Tris (benzyloxy) -S-triazine was used in place of 2,4,6-tris (2,6-dimethylphenoxy) -S-triazine used in Example 1. A heat-sensitive recording sheet of the present invention was obtained in the same manner as in Example 1 except for using the same.

Example 4. 2-anilino-3-methyl-6 used in Example 1
Use 2- (2-fluoroanilino) -6-dibutylaminofluorane instead of dibutylaminofluoran, and use 2,4,6-tris (2,6-dimethylphenoxy) -S-
A heat-sensitive recording sheet of the present invention was obtained in the same manner as in Example 1 except that 2,4,6-tris (4-n-butoxyphenoxy) -S-triazine was used instead of triazine.

Examples 5 to 9. The procedure of Example 1 was repeated except that the following compound was used in place of 2,4,6-tris (2,6-dimethylphenoxy) -S-triazine used in Example 1. Similarly, a heat-sensitive recording sheet of the present invention was obtained.

(Example 5) 2,4,6-tris (4-chlorophenoxy) -S-triazine (Example 6) 2,4,6-tris (2,4,6-trimethylphenoxy) -S- Triazine (Example 7) 2,4,6-tris (2,4-dichlorophenoxy) -S-triazine (Example 8) 2,4,6-tris (4-bromophenylthio) -S- Triazine (Example 9) 2,4,6-Tris (2-methoxyphenylthio) -S-triazine Example 10. Instead of bis (3-allyl-4-hydroxyphenyl) sulfone used in Example 1 Using 2,2-bis (4-hydroxyphenyl) propane for 2,4,6-tris (2,6-dimethylphenoxy) -S-triazine instead of 2,4,6- Tris (4-n-butylphenoxy) -S
-A heat-sensitive recording sheet of the present invention was obtained in the same manner as in Example 1 except that triazine was used.

Example 11. 2-anilino-3-methyl-6 used in Example 1
Use 2- (2-chloroanilino) -6-dibutylaminofluorane in place of dibutylaminofluoran and 2,2-bis (4) in place of bis (3-allyl-4-hydroxyphenyl) sulfone -Hydroxyphenyl) propane was used in the same manner as in Example 1 to obtain a heat-sensitive recording sheet of the present invention.

Comparative Example 1. A comparative thermosensitive recording sheet was obtained in the same manner as in Example 1 except that the solution (D) was not used.

Comparative Example 2. Instead of 2,4,6-tris (2,6-dimethylphenoxy) -S-triazine used in Example 1, 1,1,3-tris (2-methyl-4-hydroxy- A heat-sensitive recording sheet for comparison was obtained in the same manner as in Example 1 except that 5-t-butylphenyl) butane was used.

Comparative Example 3. Instead of bis (3-allyl-4-hydroxyphenyl) sulfone used in Example 1, 1,1-bis (4-hydroxyphenyl) propane was used, and the solution (D) was used. A heat-sensitive recording sheet for comparison was obtained in the same manner as in Example 1 except that it was not used.

Table 1 shows the test results for the heat-sensitive recording sheets obtained in the above Examples and Comparative Examples.

From the above comparative test results, it is apparent that the heat-sensitive recording sheet of the present invention has a sufficient coloring property and an improved plasticizer resistance of an image.

Effects of the Invention A heat-sensitive recording material which gives a color image excellent in plasticizer resistance has been obtained.

Claims (1)

(57) [Claims] 1. A thermosensitive recording material comprising, on a support, a colorless or pale-colored color-forming substance and a heat-sensitive color-forming layer mainly composed of a color-developing substance capable of coloring the color-forming substance when heated. Thermosensitive recording material characterized by containing a triazine compound represented by the following formula (I): [In formula (I), R ₁ , R ₂ and R ₃ represent hydrogen, alkyl having 1 to 5 carbon atoms, alkoxy, halogen or aralkyl having 1 to 5 carbon atoms, and X represents oxygen or sulfur. ]