JPH06210960A - Thermal recording material - Google Patents

Abstract

PURPOSE:To improve water resistance by providing a thermal color forming layer containing a specific color forming compd., a specific developer and 4- benzyloxy-4'-(2-methylglycidyl)diphenylsulfone on a support. CONSTITUTION:A color forming compd. represented by formula I (wherein X is F or Cl and Y is a 4C or less alkyl group), a compd. represented by formula II (wherein R1, R2 and R3 are hydrogen, a 5C or less alkyl group or an alkenyl group) being a developer and 4-benzyloxy-4'-(2-methylglycidyloxy) diphenylsulfone are added to and mixed with an aqueous soln. of a water-soluble polymeric compd. under stirring in respective specific amts. to prepare a coating soln. for a thermal recording layer. This coating soln. is applied to a support such as paper or a plastic sheet and dried to form the thermal recording layer to obtain a thermal recording material. The obtained thermal recording material is reduced in background fog as compared with a conventional known one and the preservability of a developed color image is improved.

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 having less background fog and excellent storage stability of a color image.

[0002]

2. Description of the Related Art A heat-sensitive recording material using a colorless or light-colored color-forming substance and a color-developing substance capable of coloring the color-forming substance under heat is disclosed in JP-B-43-4160 and JP-B-451403.
It was announced in No. 9 and has been put to practical use. Generally, in a heat-sensitive recording material, a leuco dye and a color developer such as a phenolic substance are separately dispersed in fine particles, and then both are mixed, and a binder, a sensitizer, a filler, a lubricant, etc. are added thereto. It forms a coating liquid by adding an agent and is applied to a support such as paper, film, synthetic paper, etc. Color recording by a chemical reaction that occurs when one or both of the leuco dye and the developer melt and contact by heating. And a sheet-like heat-sensitive recording material is usually prepared. A thermal printer or the like having a built-in thermal head is used for color development of such a thermal recording sheet. Compared to other recording methods, this heat-sensitive recording method is (1) no noise is generated during recording, (2) there is no need for developing and fixing, (3) maintenance-free, (4)
It is widely used in the field of facsimiles, computer output, printers such as calculators, recorders for medical measurement, ticket vending machines, thermosensitive recording labels, etc. due to the fact that machines are relatively inexpensive. .

[0003] Among these fields of use, labels are being used with the expansion of POS systems in retail stores, supermarkets, etc., and their use is increasing in train tickets for station automation systems. However, their use is a major drawback in that the color image disappears or fades due to contact with plastic sheets or water wetting.

As a method for solving such a drawback, a method of coating an aqueous emulsion of a chemically resistant resin on the heat-sensitive recording layer (JP-A-54-128347) and a method of coating a water-soluble polymer compound such as polyvinyl alcohol. (Actual development No. 50-125354), or a method of using a bisphenol derivative for the purpose of improving water resistance and storability of a color image (JP-A-57-195691, JP-A-57-20519).
1), a method using a novolac epoxy resin (Japanese Patent Laid-Open No. 2-289378), etc. have been proposed, but no sufficiently satisfactory effect has been obtained.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art. That is,
To provide a heat-sensitive recording material having high water resistance and high plasticizer property, which is unlikely to be discolored or discolored due to wetness of a color image or contact with a plastic film or the like, has little background fog under high temperature and high humidity conditions. It is in.

[0006]

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 comprising a support or a thermosensitive coloring layer containing a colorless or light-colored coloring compound and a color-developing compound as a main component capable of coloring the coloring compound under heat. It contains a compound of the following formula (1) as a compound, a compound of the following formula (2) as the color-developing compound, and further contains 4-benzyloxy-4 ′-(2-methylglycidyloxy) diphenyl sulfone. A characteristic heat-sensitive recording material is provided.

[0007]

[Chemical 3]

(In the formula (1), X represents F or Cl, and Y
Represents an alkyl group having 4 or less carbon atoms. )

[0009]

[Chemical 4]

(In the formula (2), R ₁ , R ₂ and R ₃ each independently represent hydrogen or an alkyl or alkenyl group having 5 or less carbon atoms.) In the heat-sensitive recording material of the present invention, the formula (1) is used. Of the color-developing compound of the formula (2), 4-benzyloxy-4 '-(2-methylglucidyloxy) diphenyl sulfone as a main component, and the following binder and other A thermosensitive coloring layer is prepared with a filler, other additives, and the like. 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight, of the color-developing compound of the formula (2), relative to 1 part by weight of the color-forming compound of the formula (1), 4-benzyloxy-4 ′-(2- Methylglycidyloxy) diphenyl sulfone is 0.1 to 10 parts by weight, preferably 0.1.
5 to 5 parts by weight is suitable.

Examples of the color-developing compound represented by the formula (2) include 4,4'-sulfonyldiphenol and 4,4'-.
Sulfonyl-bis- (2-allylphenol), 4-hydroxy-4'-methoxydiphenyl sulfone, 4-hydroxy-4'-ethoxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone,
4-hydroxy-4'-hydroxy-4'-butoxydiphenyl sulfone and the like can be mentioned, and these can be used alone or in combination.

Further, examples of the color-developing compounds other than the formula (2) which can be used in combination include the following.

Α-naphthol, β-naphthol, p-octylphenol, 4-t-octylphenol, p-
t-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, 2,2'-bis-
(2,5-dibromo-4-hydroxyphenyl) propane, 4,4′-isopropylidene bis (2-t-butylphenol), 2,2′-methylenebis (4-chlorophenol), bis (4-hydroxyphenyl) Phenolic compounds such as methyl acetate, bis (4-hydroxyphenyl) butyl acetate, bis (4-hydroxyphenyl) benzyl acetate, benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, 4 -Aromatic carboxylic acid derivatives such as dimethyl hydroxyphthalate, ethyl 5-hydroxyisophthalate, 3,5-di-t-butylsalicylic acid and 3.5-di-α-methylbenzylsalicylic acid, aromatic carboxylic acids or polycarboxylic acids thereof. It is commonly used for pressure-sensitive recording paper and heat-sensitive recording paper, such as valent metal salt, and is especially controlled. Not limited.

Examples of the binder include methyl cellulose,
Methoxycellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, cellulose, polyvinyl alcohol (P
VA), carboxyl group-modified polyvinyl alcohol, sulfonic acid group-modified polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch and its derivatives, casein, gelatin, aqueous isoprene rubber, alkali salt of styrene / maleic anhydride copolymer , Water-soluble substances such as alkali salts of iso (or diiso) butylene / 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-based copolymers, water-soluble emulsions such as composite particles of colloidal silica and acrylic resin are used.

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 include waxes such as animal and vegetable waxes, polyethylene wax, and synthetic wax, and higher fatty acids, higher fatty acid amides, higher fatty acid metal salts, acetylated aromatic amines, and aromatic ethers. Compounds, aromatic sulfonic acid esters, biphenyl derivatives and the like that are solid at room temperature and have a melting point of about 80 ° C. or higher can be used.

Specific examples of these compounds include caproic acid amide, capric acid amide, palmitic acid amide,
Stearic acid amide, oleic acid amide, erucic acid amide, linoleic acid amide, N-methyl stearic acid amide, stearic acid anilide, N-methyl oleic acid amide, benzanilide, linoleic acid anilide, N-ethylcaprylic acid amide, N-butyllaurin Acid amide, N-
Octadecylacetamide, N-oleinacetamide, N-oleinbenzamide, N-stearylcyclohexylamide, erucic acid amide, methylolbehenic acid amide, methylolstearic acid amide, methylenebisstearic acid amide, ethylenebisstearic acid amide, p-acetotoluidide, polyethylene Glycol,
1-benzyloxynaphthalene, 2-benzyloxynaphthalene, 1-hydroxynaphthoic acid, 1,2-bis (3-methylphenoxy) ethane, 1,2-bis (4-
Methoxyphenoxy) ethane, 1,2-bis (3,4-
Dimethylphenyl) ethane, 1-phenoxy-2- (4
-Chlorophenoxy) ethane, 1-phenoxy-2-
(4-methoxyphenoxy) ethane, 1- (2-methylphenoxy) -2- (4-methoxyphenoxy) ethane, terephthalic acid dibenzyl ester, oxalic acid dibenzyl ester, oxalic acid di (4-methylbenzyl) ester , P-benzyloxybenzoic acid benzyl ester,
p-benzylbiphenyl, m-terphenyl, 1,5-
Bis (p-methoxyphenoxy) -3-oxa-pentane, 1,4-bis (2-vinyloxyethoxy) benzene, p-biphenyl-p-tolyl ether, benzyl-
Examples of such compounds include p-methylthiophenol, phenylmesitylene sulfonate, and 4-methylphenylmesitylene sulfonate.

In addition, lubricants such as zinc stearate, calcium stearate and aluminum stearate, various surfactants, defoaming agents, ultraviolet absorbers and the like are added as required.

The heat-sensitive recording material of the present invention is prepared by using the above-mentioned material by the following method, for example. That is, according to a conventional method, the color-forming compound of the formula (1), the color-developing compound of the formula (2), and 4-benzyloxy-4 ′-(2-methylglycidyloxy) diphenyl sulfone are separately used as binders or required. Depending on the requirements, other additives are crushed and dispersed in a ball mill, attritor, sand mill, or other disperser, and then mixed to prepare a thermosensitive coloring layer coating solution, which is then applied to a support such as paper, plastic sheet, or synthetic paper. Usually, it is applied by a bar coater, a blade coater or the like so that the dry weight is 1 to 20 g / m ² (the ratio of the color forming compound to the color developing compound is usually 2: 1 to 1:10 by dry weight ratio). ) Drying to obtain the heat-sensitive recording material of the present invention.

If necessary, an intermediate layer may be provided between the thermosensitive color developing layer and the support, or an overcoat layer may be provided on the thermosensitive color developing layer. The heat-sensitive recording material of the present invention containing the color-forming compound of the formula (1), the color-developing compound of the formula (2) and 4-benzyloxy-4 ′-(2-methylglycidyloxy) diphenyl sulfone is conventionally known. It has less background fog than the ones and has good preservation of color images.

[0021]

EXAMPLES The present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. In the examples, "part" indicates part by weight.

Example 1 A mixture [A] liquid, a [B] liquid, and a [C] liquid were prepared by pulverizing and dispersing a mixture having the following composition using a sand grinder so that the average particle diameter was 2 μm or less. did. [A] liquid: 2- (o-fluoroanilino) -6-diethylaminofluorane 25 parts 25% PVA aqueous solution 20 parts water 55 parts [B] liquid: 4,4′-sulfonyl-bis- (2-allylphenol) 25 parts 25% PVA aqueous solution 20 parts water 55 parts [C] liquid: 4-benzyloxy-4 ′-(2-dimethylglycidyloxy) diphenylsulfone 25 parts 25% PVA aqueous solution 20 parts water 55 parts

Next, the preparation solutions were mixed in the following proportions to prepare a coating solution for the thermosensitive color developing layer, which was coated on a high quality paper having a basis weight of 50 g / m ² to a dry weight of about 13 g / m ² and dried. Then, a thermosensitive coloring layer was provided. Furthermore, 10% on the thermosensitive coloring layer
The PVA aqueous solution was applied and dried so that the coating amount after drying was 3 g / m ^2, and the heat-sensitive recording material of the present invention was obtained. [A] liquid 6 parts [B] liquid 24 parts [C] liquid 6 parts 50% calcium carbonate dispersion 20 parts 25% PVA aqueous solution 15 parts

Example 2 Instead of the liquid [A] of Example 1, pulverization was carried out in the same manner as in Example 1,
25% 2- (o-chloroanilino) -6 obtained by dispersion
Example 1 using a dibutylaminofluorane dispersion
A thermal recording material of the present invention was obtained in the same manner as in.

Example 3 Instead of the solution [B] of Example 1, 25% 4-hydroxy-
A thermal recording material of the present invention was obtained in the same manner as in Example 1 except that the 4'-isopropoxydiphenyl sulfone dispersion was used.

Example 4 A thermosensitive recording material of the present invention was obtained in the same manner as in Example 1 except that 25% 4,4'-sulfonyldiphenol dispersion liquid was used instead of the liquid [B] of Example 1.

A quality performance test was conducted on the thermal recording material of the present invention obtained as described above, and the results are shown in Table 1.

[0028]

[Table 1] Table 1 Quality performance test results Background 1) Color density 2) Heat resistance 3) Water resistance 4) Plasticizer resistance 5) Example 1 0.06 1.42 1.42 1.42 1.42 Example 2 0.05 1.41 1.41 1.41 1.41 Example 3 0.05 1.42 1.42 1.41 1.41 Example 4 0.05 1.38 1.38 1. 35 1.37

1) Background: A value (reflection density) obtained by measuring the uncolored portion of the sample with a Macbeth reflection densitometer RD-914 type. 2) Color density: Macbeth reflection density of the image portion printed by a thermal printer (D-805P) manufactured by Ishida Koki. 3) Heat resistance: 6 samples of color developed by the above printer
Remaining rate (%) of the density of the image area after standing for 24 hours in a thermostat at 0 ° C. 4) Water resistance: The residual ratio (%) of the density of the image area after the sample colored by the printer was immersed in tap water at room temperature for 24 hours. 5) Plasticizer resistance: P was added to the sample colored by the above printer.
0.3kg / cm with VC wrap film on both sides
The residual ratio (%) of the density of the image area after standing for 15 hours at 40 ° C. under the weight of ² .

As can be seen from the table, the heat-sensitive recording material of the present invention has little background fog and is excellent in color density, and the color image has excellent heat resistance, water resistance and plasticizer resistance.

[0031]

EFFECT OF THE INVENTION A heat-sensitive recording material having less background fogging and excellent storage stability of a color image was obtained.

Claims (1)

[Claims] 1. A heat-sensitive recording material comprising a support and a heat-sensitive color-forming layer containing a colorless or light-colored color-forming compound and a color-developing compound capable of developing a color when the color-forming compound is heated.
The compound of the following formula (1) is contained as the color-forming compound, and the compound of the following formula (2) is contained as the color-developing compound.
A heat-sensitive recording material containing -benzyloxy-4 '-(2-methylglucidyloxy) diphenyl sulfone. [Chemical 1] (In the formula (1), X represents F or Cl, and Y represents an alkyl group having 4 or less carbon atoms.) (In the formula (2), R ₁ , R ₂ and R ₃ each independently represent hydrogen, an alkyl group having 5 or less carbon atoms or an alkenyl group.)