JPH05221142A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material excellent in coloring performance, heat resistance and moisture resistance and in which fogging is suppressed by employing a coloring compound and a color developing compound therefor, each satisfying a specified general formula. CONSTITUTION:A compound satisfying formula I, e.g. 2-anilino-3-methy-6- dipentylaminofluoran, is employed as a colorless or ligh-colored coloring compound to be formed on a support such as a paper. A compound represented by formula II, e.g. bis(4 hydroxy phenyl) benzyl acetate, is employed as a compound for thermally developing the coloring compound. In formula II, R represents an alkyl group of 1-4C or general formula 3. They are then ground under presence of binder such as methy cellulose and dispersed to prepare a coating liquid to be applied on the support. A color developing agent such as alpha-naphthol may be employed together.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a heat-sensitive recording material.
More specifically, the present invention relates to a heat-sensitive recording material which is excellent in color development and has little heat resistance and heat and moisture fogging.

[0002]

2. Description of the Related Art Generally, a heat-sensitive recording material is prepared by separately dispersing a leuco dye and a color developing agent such as a phenolic substance in the form of fine particles, and then mixing them together, and then adding a binder, a sensitizer and a filler. , A coating liquid prepared by adding an additive such as a lubricant, which is applied to paper, film, synthetic paper, or the like, and one or both of the leuco dye and the developer melt by heating, and a chemical reaction caused by contact causes This is to obtain a color development record. A thermal printer or the like having a built-in thermal head is used for coloring the thermal recording sheet. Compared with other recording methods, this heat-sensitive recording method has (1) no noise during recording,
Due to the features such as (2) no need for development and fixing, (3) maintenance-free, (4) relatively inexpensive machines, the field of facsimiles, computer output, printers such as calculators, medical It is widely used in the fields of measurement recorders, automatic ticket vending machines, and heat-sensitive recording labels.

Among these application fields, the use of labels and station automation systems for passenger tickets has recently increased with the expansion of POS systems in retail stores and supermarkets. The problem in these applications is heat,
It is that fog is caused by the humidity. Further, in recent years, the demand for high-speed recording has further increased, and development of a heat-sensitive recording material capable of sufficiently responding to high-speed recording has been strongly desired. That is the drawback. Various methods have been proposed in order to obtain good heat response and high heat resistance and heat and humidity resistance, but a satisfactory method has not been established yet.

[0004]

The objects of the present invention are as follows.
It is to solve the drawbacks of the prior art. That is, it is to provide a heat-sensitive recording material having high sensitivity and good storage stability against heat and humidity.

[0005]

The inventors of the present invention have completed the present invention as a result of various studies to achieve the above object. That is, the present invention provides a thermosensitive recording material having a thermosensitive color-forming layer containing a colorless or light-colored color-forming substance and a color-developing substance capable of coloring the color-forming substance on heat on a support. The present invention also provides a heat-sensitive recording material characterized by containing a substance represented by the following formula (1) and a substance represented by the following formula (2) as the color-developing substance.

[0006]

[Chemical 4]

[0007]

[Chemical 5]

(In the formula (2), R is an alkyl group having 1 to 4 carbon atoms or

[0009]

[Chemical 6]

Represents The present invention will be described in detail. The present invention comprises the above-mentioned color-forming compound of formula (1) and the color-developing compound of formula (2) as main components, but if necessary, a heat-fusible compound, a filler and a surfactant. It can be contained in the thermosensitive coloring layer together with the binder described later. Further, the above color developer can be used in combination with another color developer.

Examples of developers that can be used in combination include α-naphthol, β-naphthol, p-octylphenol and 4-t.
-Octylphenol, pt-butylphenol, p
-Phenylphenol, 1,1'-bis (p-hydroxyphenyl) propane, 2,2'-bis- (p-hydroxyphenyl) propane, 2,2'-bis (p-hydroxyphenyl) butane, 1,1 '-Bis (p-hydroxyphenyl) cyclohexane, 4,4'-thiobisphenol, 4,4'-cyclo-hexylidene diphenol,
4,4'-sulfonyldiphenol, 4,4'-sulfonyl-bis (2-allylphenol), 2,2'-bis (2,5-dibromo-4-hydroxyphenyl) propane, 4,4'-isopropyi Phenolic compounds such as lidene bis (2-t-butylphenol) and 2,2′-methylenebis (4-chlorophenol), benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, 4-
Dibenzyl hydroxyphthalate, dimethyl 4-hydroxydiphthalate, ethyl 5-hydroxyisophthalate, 3,
Examples thereof include aromatic carboxylic acid derivatives such as 5-di-t-butylsalicylic acid and 3,5-di-α-methylbenzylsalicylic acid, aromatic carboxylic acids or polyvalent metal salts thereof.

A binder is used in the preparation of the heat-sensitive recording material of the present invention. Examples of the binder that can be used include methyl cellulose, methoxy cellulose, hydroxyethyl cellulose, carboxymethyl cellulose,
Sodium carboxymethyl cellulose, cellulose,
Polyvinyl alcohol (PVA), carboxyl group-modified polyvinyl alcohol, sulfonic acid group-modified polyvinyl alcohol, acetoacetylated polyvinyl alcohol, silica-modified polyvinyl alcohol, alkali salt of acrylic acid-styrene copolymer, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, Water-soluble substances such as starch and its derivatives, casein, gelatin, alkali salts of styrene / maleic anhydride copolymer, or polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, polystyrene, polyacrylic acid ester, polyurethane, styrene / Butadiene (SB) copolymer, carboxylated styrene / butadiene (sb) copolymer, styrene / butadiene / acrylic acid copolymer, colloidal silica / acrylic resin composite particles, etc. Water-soluble emulsion, and the like.

Examples of fillers that can be used are calcium carbonate, magnesium carbonate, magnesium oxide, silica,
There are white carbon, talc, clay, alumina, magnesium hydroxide, aluminum hydroxide, aluminum oxide, barium sulfate, polystyrene resin, urea-formalin resin and the like.

Examples of heat-fusible compounds that can be used are waxes such as animal and vegetable waxes, polyethylene waxes, synthetic waxes and the like, higher fatty acids, higher fatty acid amides, higher fatty acid metal salts, acetyl compounds of aromatic amines, aromatics. Examples thereof include ether compounds and biphenyl derivatives which are solid at room temperature and have a melting point of about 80 ° C. or higher.

In addition, as 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 using the above-mentioned material, for example, by the following method. That is, first, a color-developing substance and a color-developing substance are separately ball-milled together with a binder or, if necessary, other additives.
A thermosensitive recording layer coating liquid is prepared by pulverizing and dispersing with a disperser such as an attritor or a sand mill, and the weight when dried is usually 1 on a support such as paper, a plastic sheet, or synthetic paper. The heat-sensitive recording material of the present invention is obtained by coating with a bar coater, a blade coater or the like so that the coating amount becomes about ²⁰ g / m ² and drying. The ratio of the color-developing substance to the color-developing substance is usually 1: 1 to 1:10 in dry weight ratio. 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 chromogenic substance of the above formula (1) and the above formula (2)
The heat-sensitive recording material of the present invention using the above-mentioned color-developing substance has higher sensitivity than the conventionally known materials, has good storage stability against heat and humidity, and has little background fog.

[0018]

EXAMPLES The present invention will be described in more detail by way of examples, but the present invention is not limited thereto. In the examples, “part” means “part by weight”.

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

(A) Liquid 2-anilino-3-methyl-6-dipentylaminofluorane 30 parts 25% polyvinyl alcohol aqueous solution 20 parts water 50 parts (B) Liquid bis (4-hydroxyphenyl) benzyl benzyl 15 parts 25% Polyvinyl alcohol aqueous solution 5 parts Calcium carbonate 20 parts Carboxylated SB latex (50%) 10 parts Water 50 parts

Next, the liquid (A) and the liquid (B) are mixed at a ratio of 15:85 to prepare a thermosensitive color forming layer-forming liquid having a basis weight of 50.
the liquid volume in fine paper in g / m ² is coated to a 20 g / m ^2, and dried to obtain a heat-sensitive recording material of the present invention.

Example 2 The present invention was carried out in the same manner as in Example 1 except that methyl bis (4-hydroxyphenyl) acetate was used instead of benzyl bis (4-hydroxyphenyl) acetate in (B). A heat-sensitive recording material of was obtained.

Example 3 On the thermosensitive coloring layer of the thermosensitive recording material obtained in the same manner as in Example 1, a 10% PVA aqueous solution was further dried to give a weight of 3 g / m 2.
^It was coated so as to be ² and dried to obtain the thermal recording material of the present invention with an overcoat.

Comparative Example 1 A thermal recording material for comparison was prepared in the same manner as in Example 1 except that bisphenol A was used in place of the benzyl bis (4-hydroxyphenyl) acetate in the liquid (B). Obtained.

Comparative Example 2 In Example 1, bis- (3-allyl-) was used instead of benzyl bis (4-hydroxyphenyl) acetate in solution (B).
A thermal recording material for comparison was obtained in the same manner as in Example 1 except that 4-hydroxyphenyl) -sulfone was used.

Comparative Example 3 In Example 1, instead of 2-anilino-3-methyl-6-dipentylaminofluorane in the solution (A), 2-anilino-3-methyl-6-dipentylaminofluorane was used.
A heat-sensitive recording material for comparison was obtained in the same manner as in Example 1 except that anilino-3-methyl-6-diethylaminofluorane was used.

Comparative Example 4 In Example 1, instead of 2-anilino-3-methyl-6-dipentylaminofluorane in solution (A),
A thermal recording material for comparison was obtained in the same manner as in Example 1 except that anilino-3-methyl-6-dibutylaminofluorane was used.

Comparative Example 5 In Example 1, in place of 2-anilino-3-methyl-6-dipentylaminofluorane of the liquid (A), 2-
Anilino-3-methyl-6-dibutylaminofluorane was used, and bis- (3-allyl-4-hydroxyphenyl) -sulfone was used instead of benzyl bis (4-hydroxyphenyl) acetate in solution (B). A thermal recording material for comparison was obtained in the same manner as in Example 1.

Using the heat-sensitive recording material of the present invention and the heat-sensitive recording material for comparison which were obtained as described above, the following quality performance tests were conducted.

Table 1 Quality performance test Dynamic sensitivity (V) Heat resistance Moisture and heat resistance 21 23 25 27 Example 1 1.09 1.49 1.57 1.57 0.08 0.10 Example 2 1.05 1.41 1.57 1.57 0.08 0.10 Example 3 1.07 1.47 1.56 1.56 0.08 0.10 Comparative Example 1 0.80 1.32 1.44 1.49 0.10 0.15 Comparative Example 2 0.95 1.37 1.51 1.51 0.11 0.18 Comparative Example 3 1.06 1.48 1.55 1.55 0.12 0.19 Comparative Example 4 1.10 1.50 1.50 1.50 0.13 0.20 Comparative Example 5 1.06 1.45 1.49 1.50 0.15 0.26

1) Dynamic Sensitivity: A value measured by a Macbeth reflection densitometer RD-914 type when the color density of each sample (V) was printed on a sample with a thermal printer (D-508P) manufactured by Ishida Koki Co., Ltd. 2 ) Heat resistance: A value measured by a Macbeth reflection densitometer for the color density of the background after leaving it in a dryer at 70 ° C for 24 hours. 3) Moisture resistance: The background after leaving it in an atmosphere at 70 ° C and 90% RH for 24 hours. Value measured by Macbeth reflection densitometer, as is clear from Table 1, the thermal recording material of the present invention is superior in color density, heat resistance and moist heat resistance to the thermal recording material for comparison.

[0032]

EFFECTS OF THE INVENTION A heat-sensitive recording material excellent in color development, heat resistance and less fogging due to heat and humidity was obtained.

Claims (1)

[Claims] 1. A thermosensitive recording material comprising a support and a thermosensitive coloring layer mainly comprising a colorless or light-colored coloring compound and a color-developing compound capable of coloring the coloring compound when heated. A thermosensitive recording material comprising a compound of the following formula (1) as a compound and a compound of the following formula (2) as the color-developing compound. [Chemical 1] [Chemical 2] (In the formula (2), R is an alkyl group having 1 to 4 carbon atoms or Represents)