JP2000289331A - Heat-sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize the fog of a texture under high temperature and high humidity conditions and donate high water resistance, high plasticity and the like by adding a chemical compound represented by a specific formula to a heat-sensitive coloring layer which is formed on a support and composed mainly of a colorless or a pale-color coloring compound and a developing compound. SOLUTION: A heat-sensitive recording material is prepared by forming a heat-sensitive coloring layer composed mainly of a colorless or pale-color coloring compound and a developing compound which makes the color developing compound develop a color during heating, on a support. In this case, a chemical compound represented by the formula is added to the heat-sensitive coloring layer. With regard to the ratio of the components added to the heat- sensitive coloring layer, the chemical compound represented by the formula suitably accounts for 1-50 wt.% and best suitably accounts for 2-30 wt.% to the total weight of 100% of the coloring layer. On the other hand, the addition amount of the developing compound is suitably 1-50 wt.% and the addition amount of the developing compound is suitably 5-80 wt.%. The best- recommended coloring compounds are a fluoran compound, a triaryl methane compound, a spiro compound and the like.

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 excellent storage stability and high color density and color sensitivity.

[0002]

2. Description of the Related Art A heat-sensitive recording material utilizing 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 JP-B-43-4160 and JP-B-45-1403.
No. 9 etc. and widely used. Generally, a thermosensitive recording material is prepared by separately dispersing a developer such as a leuco dye and a phenolic substance into fine particles separately, then mixing the two, and adding a binder, a sensitizer, a filler, a lubricant, etc. Adds an agent to form a coating solution, and is applied to a support such as paper, film, or synthetic paper. Heating allows the leuco dye and / or the developer to melt and come into contact with the color reaction to form a color reaction record. In general, a sheet-like heat-sensitive recording material is prepared. For color development of such a heat-sensitive recording sheet, a thermal printer or the like having a built-in thermal head is used. Compared with other recording methods, this heat-sensitive recording method is (1) no noise is generated at the time of recording, (2) there is no need for developing and fixing, (3) maintenance-free, and (4)
It is widely used in the facsimile field, computer output, printers such as calculators, recorders for medical measurement, automatic ticket vending machines, heat-sensitive recording labels, etc. .

[0003] Among these fields of use, labels are increasing with the expansion of POS systems such as retail stores and supermarkets, and their use is increasing for tickets for station automation systems. However, a major drawback in their use is that the color image disappears or discolors due to contact with plastic sheets or wetness of water. As a method for solving such a defect, a method of applying an aqueous emulsion of a resin having chemical resistance on the heat-sensitive recording layer (Japanese Patent Laid-Open No. 128347/1979) and a method of applying a water-soluble polymer compound such as polyvinyl alcohol (Japanese Utility Model Application) 50-125354), and a method of using a bisphenol derivative for the purpose of enhancing water resistance and preservation of a color image (JP-A-57-195691, JP-A-57-20519).
1), a method using a novolak epoxy resin (JP-A-2-289378) and the like have been proposed, but a satisfactory effect has not been obtained. In addition, there is an increasing demand for high-speed recording and high-density recording, and there is a strong demand for not only high-speed recording apparatuses but also development of a more sensitive thermosensitive recording material that can respond to this.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the disadvantages of the prior art as described above. That is,
Decoloring and fading due to contact with water and plastic films etc. of the colored image are unlikely to occur, there is little background fog under high temperature and high humidity conditions, and it has high water resistance, high plasticizer preservability, and An object of the present invention is to provide a heat-sensitive recording material having high sensitivity.

[0005]

The present inventor has made various studies to achieve the above object, and as a result, completed the present invention. That is, the present invention relates to (1) a heat-sensitive recording material comprising a support provided with a colorless or pale-colored color-forming compound and a heat-sensitive color-forming layer containing, as a main component, a color-developing compound capable of coloring the color-forming compound when heated. The following formula (1) is contained in the thermosensitive coloring layer.

[0006]

Embedded image

A heat-sensitive recording material characterized by containing a compound represented by the formula:

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the heat-sensitive recording material of the present invention, a compound represented by the formula (1) and a color-forming compound, a color-developing compound, a binder and other fillers as required are shown below. A heat-sensitive coloring layer is prepared by using a heat-fusible compound, a surfactant, etc., so that discoloration and fading hardly occur, and background fog under high-temperature and high-humidity conditions is reduced.
A highly sensitive thermosensitive recording paper having high water resistance, high plasticizer preservability and high sensitivity can be obtained. The compound represented by the formula (1)
AS No. No. 6683-19-8 is a known compound registered in Chemical Abstracts.

The proportion of each component in the thermosensitive coloring layer is 100% by weight of the total weight of the layer, and the compound represented by the formula (1) is 1 to 50% by weight, preferably 2 to 30% by weight. 1 to 50% by weight of the color-forming compound, 5 to 80% by weight of the color-developing compound, 1 to 90% by weight of the binder, 0 to 80% by weight of the filler and the heat-fusible compound, and other lubricants, Surfactants, defoamers, ultraviolet absorbers and the like are each used in an arbitrary ratio, for example, 0 to 30% by weight, respectively.

Examples of the coloring compound used in the thermosensitive coloring layer are not particularly limited as long as they are those generally used in pressure-sensitive recording paper or thermosensitive recording paper. Specific examples include fluoran compounds, triarylmethane compounds, spiro compounds, diphenylmethane compounds, thiazine compounds, lactam compounds, and fluorene compounds.

The fluoran compounds include, for example, 3-
Diethylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilino Fluoran, 3- (N
-Ethyl-N-isopentylamino) -6-methyl-7
-Anilinofluoran, 3-isobutylethylamino-
6-methyl-7-anilinofluoran, 3- [N-ethyl-N- (3-ethoxypropyl) amino] -6-methyl-7-anilinofluoran, 3- (N-ethyl-N-
Hexylamino) -6-methyl-7-anilinofluoran, 3-dipentylamino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-propylamino)
-6-methyl-7-anilinofluoran, 3- (N-ethyl-N-tetrahydrofurylamino) -6-methyl-
7-anilinofluoran, 3-diethylamino-6-methyl-7- (p-chloroanilino) fluoran, 3-
(P-toluidinoethylamino) -6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-
7- (p-toluidino) fluoran, 3-diethylamino-7- (o-chloroanilino) fluoran, 3-dibutylamino-7- (o-chloroanilino) fluoran,
3-diethylamino-7- (o-fluoroanilino) fluoran, 3-dibutylamino-7- (o-fluoroanilino) fluoran, 3-diethylamino-7- (3,
4-dichloroanilino) fluorane, 3-pyrrolidino-
6-methyl-7-anilinofluoran, 3-diethylamino-6-chloro-7-ethoxyethylaminofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-diethylamino-7-chlorofluor Orane, 3-diethylamino-6-chloro-7-methylfluoran, 3-diethylamino-7-methylfluoran,
3-diethylamino-7-octylaminofluoran,
3-diethylamino-7-phenylfluoran, 3-
(P-toluidinoethylamino) -6-methyl-7-phenethylfluoran and the like.

Examples of triarylmethane compounds include 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone or CVL) and 3,3-bis (p
-Dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylaminoindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methyl Indole-3-
Yl) phthalide, 3- (p-dimethylaminophenyl)
-3- (2-Phenylindol-3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-
Yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-bis) 9-ethylcarbazol-3-yl) -5-dimethylaminophthalide,
3,3- (2-phenylindol-3-yl) -5
Dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6-dimethylaminophthalide and the like.

Further, as the spiro compound, for example, 3
-Methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, 3-benzylcipirodinaphthopyran, 3-propylspirobenzopyran, 3-methylnaphtho- (3-methoxybenzopyran ) Spiropyran, 1,3,3-trimethyl-6
-Nitro-8'-methoxyspiro (indoline-2,
2′-benzopyran) and the like as diphenylmethane-based compounds, for example, N-halophenyl-leukoauramine, 4,4-bis-dimethylaminophenylbenzhydryl benzyl ether, N-2,4,5-trichlorophenylleucoura As a thiazine-based compound, for example, benzoyl leucomethylene blue and p-nitrobenzoyl leucomethylene blue, and as a lactam-based compound, for example, rhodamine B anilinolactam,
Rhodamine B-p-chloroanilinolactam and the like are fluorene-based compounds, for example, 3,6-bis (dimethylamino) fluorenespiro (9,3 ′)-6-′dimethylaminophthalide, 3,6-bis ( Dimethylamino)
Fluorene spiro (9,3 ')-6'-pyrrolidinophthalide, 3-dimethylamino-6-diethylaminofluorene spiro (9,3')-6'-pyrrolidinophthalide]
And the like. These color-forming compounds are used alone or in combination of two or more.

The color-developing compound is not particularly limited as long as it is generally used in pressure-sensitive recording paper or heat-sensitive recording paper. Examples thereof include phenolic compounds, aromatic carboxylic acid derivatives having a phenolic hydroxyl group, and aromatic carboxylic acids. Examples thereof include an acid or a metal salt thereof.

As the phenolic compound, for example, α-
Naphthol, β-naphthol, p-octylphenol, 4-t-octylphenol, pt-butylphenol, p-phenylphenol, 1,1-bis (p-
Hydroxyphenyl) propane, 2,2-bis (p-hydroxyphenyl) propane (also called bisphenol A)
Or BPA), 2,2-bis (p-hydroxyphenyl) butane, 1,1-bis (p-hydroxyphenyl)
Cyclohexane, 4,4′-thiobisphenol, 4,
4'-cyclohexylidenediphenol, 2,2'-
(2,5-dibromo-4-hydroxyphenyl) propane, 4,4-isopropylidenebis (2-t-butylphenol), 2,2'-methylenebis- (4-chlorophenol), 4,4'-dibenzyl Xydiphenyl sulfone, 2,4′-dihydroxydiphenyl sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone,
-Hydroxy-4'-methoxydiphenyl sulfone, 4
-Hydroxy-4'-ethoxydiphenyl sulfone, 4
-Hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxy-4'-butoxydiphenylsulfone and the like.

Examples of the aromatic carboxylic acid derivative or aromatic carboxylic acid include methyl bis (4-hydroxyphenyl) acetate, butyl bis (4-hydroxyphenyl) acetate, benzyl bis (4-hydroxyphenyl) acetate, and 2,4. Phenolic compounds such as -dihydroxy-2'-methoxybenzanilide, benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, dimethyl 4-hydroxyphthalate, ethyl 5-hydroxyisophthalate, Examples thereof include aromatic carboxylic acid derivatives such as 3,5-di-t-butylsalicylic acid and 3,5-di-α-methylbenzylsalicylic acid, aromatic carboxylic acids and metal salts thereof.

Examples of usable binders include methylcellulose, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, cellulose, polyvinyl alcohol (PVA), carboxyl group-modified polyvinyl alcohol, sulfonic acid group-modified polyvinyl alcohol, polyvinyl pyrrolidone, Water solubility of polyacrylamide, polyacrylic acid, starch and derivatives thereof, casein, gelatin, aqueous isoprene rubber, alkali salt of styrene / maleic anhydride copolymer, iso (or diiso) butylene / maleic anhydride copolymer salt, etc. Or styrene /
Butadiene (SB) copolymer, carboxylated styrene / butadiene (SB) copolymer, styrene / butadiene / acrylic acid copolymer, polyvinyl acetate, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, polystyrene, Hydrophobicity of acrylic resin, acrylic / styrene resin, polyacrylate, polyester, polycarbonate, polyurethane, polybutyral, epoxy resin, furan resin, vinyltoluene resin, rosin ester resin, composite particles of colloidal silica and acrylic copolymer, etc. Polymer compounds or their emulsions.

Other additives used as needed include, for example, fillers and heat-fusible compounds (sensitizers). Examples of the filler include calcium carbonate, magnesium carbonate, magnesium oxide, silica, white carbon, talc, clay, alumina, magnesium hydroxide, aluminum hydroxide, aluminum oxide, barium sulfate, polystyrene resin, acrylic resin, polyolefin resin, and benzoguanamine. Resin, melamine resin, urea
Formalin resin and the like can be mentioned.

Examples of the heat-fusible compound include waxes such as animal and vegetable waxes and synthetic waxes, higher fatty acids, higher fatty acid amides, higher fatty acid anilides, acetylated aromatic amines, naphthalene derivatives, aromatic ethers and aromatics. Carboxylic acid derivatives, aromatic sulfonic acid ester derivatives, carbonic acid or oxalic acid diester derivatives, biphenyl derivatives, terphenyl, etc.
Those having a melting point of not less than ° C can be used.

Examples of waxes include wood wax, carnauba wax, shellac, paraffin, montan wax,
Acid or paraffin, polyethylene wax, polyethylene oxide, etc., as higher fatty acids, for example, stearic acid,
Examples of higher fatty acid amides such as behenic acid include stearic acid amide, oleic acid amide, N-methylstearic acid amide, erucic acid amide, methylolbehenic acid amide, methylolstearic acid amide, methylenebisstearic acid amide, and ethylenebisstearin Examples of acid amides include higher fatty acid anilides such as stearic acid anilide and linoleic acid anilide, and examples of acetylated aromatic amines include acetotoluizide.

The naphthalene derivatives include, for example, 1
-Benzyloxynaphthalene, 2-benzyloxynaphthalene, 1-hydroxynaphthoic acid phenyl ester and the like, as aromatic ethers, for example, 1,2-diphenoxyethane, 1,4-diphenoxyethane, 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
Examples of aromatic carboxylic acid derivatives include, for example, p-hydroxybenzoic acid benzyl ester, p-benzyloxybenzoic acid benzyl ester, and terephthalic acid dibenzyl ester; and aromatic sulfonic acid. As ester derivatives, for example, p-toluenesulfonic acid phenyl ester, phenylmesitylenesulfonate, 4-methylphenylmesitylenesulfonate and the like, and as carbonic acid or oxalic acid diester derivatives, for example, diphenyl carbonate, dibenzyl oxalate, oxalic acid Di (4-methylbenzyl) ester, oxalic acid di (4-chlorobenzyl) ester and the like include biphenyl derivatives such as p-benzylbiphenyl and p-benzylbiphenyl.
-Allyloxybiphenyl and the like and terphenyl derivatives include, for example, m-terphenyl and the like.

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

Using the above materials, the heat-sensitive recording material of the present invention is prepared, for example, by the following method. That is, first, the color-forming compound, the color-developing compound, and the compound of the formula (1) are separately pulverized together with a binder or, if necessary, other additives by a dispersing machine such as a ball mill, an attritor, or a sand mill by an ordinary method. After dispersion, the compound of formula (1) may be mixed in advance with a color-forming compound or a color-developing compound for dispersion to prepare a thermosensitive color-forming layer coating solution, and then formed into paper, a plastic sheet, and synthesized. Coating on a support such as paper with a bar coater, a blade coater or the like so that the dry weight is usually 1 to 20 g / m ² (the ratio of the color-forming compound to the color developing compound is usually 2: 1-1: 1
0) to obtain the heat-sensitive recording material of the present invention.

If necessary, an intermediate layer may be provided between the thermosensitive coloring layer and the support, or an overcoat layer may be provided on the thermosensitive coloring layer. The intermediate layer and the overcoat layer are pulverized and dispersed in the same manner as in the preparation of the thermosensitive coloring layer coating solution together with a binder or other additives as necessary, to obtain an intermediate layer coating solution or a protective layer coating solution, and then dried. It is applied so that the weight at the time is usually 0.1 to 30 g / m ² .

[0025]

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

Example 1 A mixture having the following composition was pulverized and dispersed using a sand grinder so that the average particle diameter became 2 μm or less, and the solution [A], the solution [B] and the solution [C] were respectively obtained. Prepared. [A] solution: 2-anilino-3-methyl-6-dibutylaminofluoran 25 parts 25% PVA aqueous solution 20 parts water 55 parts [B] solution: 4-hydroxy-4'-isopropoxydiphenyl sulfone 25 parts 25% Liquid PVA 20 parts Water 55 parts [C] Liquid: Compound of formula (1) 25 parts 25% PVA aqueous solution 20 parts Water 55 parts

Next, each of the prepared solutions was mixed at the following ratio to prepare a coating solution for the thermosensitive coloring layer, and dried on a synthetic paper having a thickness of 80 μm (trade name: Yupo FPG80, manufactured by Oji Yuka Synthetic Paper Co., Ltd.). It is applied so that the weight at the time becomes about 10 g / m ² and dried to obtain a thermosensitive coloring layer. [A] solution 8 parts [B] solution 24 parts [C] solution 16 parts 50% calcium carbonate dispersion 10 parts 40% styrene / acrylic ester copolymer emulsion 20 parts (formation of protective layer) Is applied onto the above-mentioned thermosensitive coloring layer so that the weight when dried is 3 g / m ^2, and dried to obtain the thermosensitive recording material of the present invention. 40% styrene / acrylate copolymer emulsion 20 parts 5% bentonite dispersion 40 parts 30% zinc stearate dispersion 3 parts

Example 2 25% 3- (N-ethyl-N-isopentylamino) -pulverized and dispersed in the same manner as in Example 1 except that the solution [A] was used.
A heat-sensitive recording material of the present invention is obtained in the same manner as in Example 1 using a 6-methyl-7-anilinofluorane dispersion.

Example 3 The same procedure as in Example 1 was repeated except that the 25% 3-dibutylamino-7- (o-chloroanilino) fluoran dispersion, which had been pulverized and dispersed in the same manner as in Example 1, except for the solution [A], was used. Thus, the heat-sensitive recording material of the present invention is obtained.

Example 4 In the same manner as in Example 1, except that the liquid [B] of Example 1 was replaced with a 25% 2,4'-dihydroxydiphenylsulfone dispersion that had been pulverized and dispersed in the same manner as in Example 1, A heat-sensitive recording material is obtained.

Example 5 In the same manner as in Example 1 except that the 25% bis (3-allyl-4-hydroxyphenyl) sulfone dispersion, which was similarly ground and dispersed, was used in place of the solution [B] of Example 1, To obtain the heat-sensitive recording material of the present invention.

Tables 1 and 2 show the quality performance of the heat-sensitive recording material of the present invention obtained as described above.

Table 1 Quality Performance Table Background 1) Color density 2) Heat resistance 3) Heat resistance 4) Moisture resistance 5) Example 1 0.02 1.65 0.03 1.60 0.02 Example 2 02 1.67 0.03 1.62 0.03 Example 3 0.02 1.60 0.02 1.54 0.02 Example 4 0.02 1.60 0.02 1.55 0.02 Example Example 5 0.03 1.63 0.05 1.60 0.04

[0034]

1) Background: A value (reflection density) of an uncolored portion of the prepared sample measured by a Macbeth reflection densitometer RD-914. 2) Color density: Macbeth reflection density of a portion printed by a commercially available thermal printer (D-805P, manufactured by Ishida). 3) Heat resistance: Macbeth reflection density of an unprinted portion of a sample left for 24 hours in a thermostat at 60 ° C. 4) Heat resistance: Macbeth reflection density of a portion printed by the above-mentioned printer of a sample left for 24 hours in a thermostat at 60 ° C. 5) Moisture resistance: Macbeth reflection density of an unprinted portion of a sample left for 24 hours in a constant humidity chamber at 40 ° C. and 90% relative humidity. 6) Moisture resistance: Macbeth reflection density of a portion printed by the above-described printer on a sample left for 24 hours in a constant humidity chamber at 40 ° C. and a relative humidity of 90%. 7) Water resistance: Macbeth reflection density of a printed portion after immersing a sample printed by the above printer in tap water at room temperature for 24 hours. 8) Plasticizer resistance: Macbeth reflection density of a printed portion after a PVC wrap film was placed above and below a sample printed by the printer and allowed to stand at 25 ° C. for 24 hours under a load of 30 g / cm ² .

As is clear from the table, the heat-sensitive recording material of the present invention is hardly decolored or faded, has little background fog under high temperature and high humidity conditions, and has good water resistance and high plasticizer properties. It has storability and high color density.

[0037]

The heat-sensitive recording material of the present invention containing the compound represented by the formula (1) is characterized in that the background fog is small, the preservability of a color image is excellent, and the color sensitivity is high. That is, it is difficult for decoloring or fading due to contact with water or plastic films, etc. of the colored image to occur, less background fog under high temperature and high humidity conditions, high water resistance, and high plasticizer preservability. In addition, a highly sensitive thermosensitive recording material can be obtained.

Claims (1)

[Claims] 1. A thermosensitive recording material comprising a support and a thermosensitive coloring layer containing a colorless or pale-colored coloring compound and a developing compound capable of causing the coloring compound to develop color when heated. The following formula (1) A heat-sensitive recording material comprising a compound represented by the formula: