JPH06336082A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material reduced in background fog and excellent in the preservability of a recording image against chemicals such as a plasticizer or the like and recording sensitivity. CONSTITUTION:In a thermal recording material wherein a recording layer containng a colorless or light-colored basic dye and a developer is provided on a support, 3-(N-ethyl-N-ethoxypropylamino)-6-methyl-7-anilinofluorane and 4-benzyloxy-4'-(2-methyl-2,3-epoxypropyloxy)diphenylsulfone are added to the recording layer.

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 having less background fog, excellent storability of a recorded image against chemicals such as oils and fats and plasticizers, and excellent recording sensitivity. .

[0002]

2. Description of the Related Art Heretofore, a heat-sensitive recording material has been well known which uses a heat energy of a heat-sensitive head or the like to develop a colorless or light-colored basic dye and a color developer. Since such a thermal recording material is relatively inexpensive and the recording equipment is compact and its maintenance is relatively easy, it is used not only as a recording medium for facsimiles and various computers but also in a wide range of fields such as thermal labels. .

In recent years, recording speeds of 10 seconds or less in A4 size for thermal fax and 120 characters / second or more for thermal printer have become possible, and there is a further demand for higher sensitivity of the thermal recording material. In addition, the use of heat-sensitive recording labels is increasing with the expansion of POS systems aimed at labor saving in the retail industry. However, in a normal thermal recording material, fogging occurs due to a plasticizer, a solvent, etc.
It has the drawback of discoloration due to chemicals. Therefore, for example, water-based pen, oil-based pen, highlighter pen,
Touching stationery such as red meat, adhesive, glue, diazo developer and office supplies, etc., or cosmetics such as hand cream, emulsion will cause white part to develop color, the density of the recorded image will decrease significantly, and the color will change. However, the product value was significantly impaired. For the purpose of improving such defects, various proposals have been made such as a method of providing a protective layer on the recording layer and a method of adding a storage stability improver to the recording layer, but all of them have new defects. However, since it is not always possible to obtain a sufficiently satisfactory effect, further improvement is strongly demanded. For example, JP-A-4-179579 discloses 4-benzyloxy-4 '-(2-methyl-2) as a preservative improving agent for a recorded image formed by a reaction of a colorless or light-colored basic dye and a color developing agent. Although a heat-sensitive recording material using 3,3-epoxypropyloxy) diphenyl sulfone is described, it has a problem in storability against chemicals such as plasticizer at high temperature.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a thermosensitive recording medium which has little background fog and is excellent in storability of a recorded image with respect to chemicals such as plasticizers and recording sensitivity.

[0005]

DISCLOSURE OF THE INVENTION The present inventors have proposed a thermosensitive recording medium comprising a support and a recording layer containing a colorless or light-colored basic dye and a color-forming agent. −
(N-Ethyl-N-ethoxypropylamino) -6-methyl-7-anilinofluorane and 4-benzyloxy-
It was found that the above object can be achieved by incorporating 4 '-(2-methyl-2,3-epoxypropyloxy) diphenyl sulfone, and the present invention has been completed.

[0006]

The present invention provides a colorless or light-colored basic dye as 3
-(N-ethyl-N-ethoxypropylamino) -6-
Methyl-7-anilinofluorane and 4-benzyloxy-4 '-(2-methyl-2,3-
By using epoxypropyloxy) diphenyl sulfone, the preservability of a recorded image by a plasticizer, a hand cream, etc. was further improved without impairing the characteristics of color development sensitivity. In the present invention, the amounts of the specific basic dye and the specific storage stability improver to be used are not particularly limited, but for the specific basic dye, the coloring agent 1 is used.
10 to 200 parts by weight with respect to 00 parts by weight, and 5 to 30 parts with respect to 100 parts by weight of the coloring agent for a specific storage stability improving agent
It is desirable to adjust within the range of about 0 parts by weight.

Further, 4,4'-dihydroxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, 4-hydroxy 4'-benzyloxydiphenyl sulfone, as a coloring agent, By using at least one of bis (3-allyl-4-hydroxyphenyl) sulfone, a heat-sensitive recording material with less background fog can be obtained.

The present invention provides 3- (N-ethyl-N-ethoxypropylamino)-as a colorless to light-colored basic dye.
Although 6-methyl-7-anilinofluorane is used, it is also possible to use the following known colorless to light-colored basic dyes in combination as long as the effects of the present invention are not impaired. 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide, Three
-Diethylamino-7-dibenzylamino-benzo [a] fluorane, 3- (N-ethyl-Np-tolyl) amino-7-N-methylanilinofluorane, 3-
Diethylamino-7-anilinofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3,6-
Bis (diethylamino) fluorane-γ-anilinolactam, 3-cyclohexylamino-6-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-chlorofluorane,
3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-
Cyclohexyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane , 3-di (n-pentyl) amino-6-methyl-7-anilinofluorane, 3
-Diethylamino-7- (o-chlorophenylamino)
Fluorane, 3-di (n-butyl) amino-7- (o-
Chlorophenylamino) fluorane, 3-diethylamino-7- (o-fluorophenylamino) fluorane,
3-di (n-butyl) amino-7- (o-fluorophenylamino) fluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane, 3-
(N-ethyl-p-toluidino) -6-methyl-7-
(P-Toluidino) fluorane, 3- (N-ethyl-N)
-Furfurylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3- (N-methyl-Nn-propylamino) -6-methyl -7-Anilinofluorane, 3,3
-Bis [1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-2-yl] -4,
5,6,7-Tetrachlorophthalide, 3,3-bis [1
-(4-Methoxyphenyl) -1- (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, 3,3-bis [1,1-bis (4 −
Pyrrolidinophenyl) ethylene-2-yl] -4,5,
6,7-Tetrabromophthalide, 3-p- (p-anilinoanilino) anilino-6-methyl-7-chlorofluorane, 2,2-bis {4- [6 '-(N-cyclohexyl-N-methyl Amino) -3'-methylspiro [phthalide-3,9'-xanthene-2'-ylamino] phenyl} propane, 3,6, -bis (dimethylamino) fluorene-9-spiro-3 '-(6'-dimethyl) amino)
Examples thereof include phthalide.

In the heat-sensitive recording material of the present invention, as the color former used for developing the color of the specific basic dye contained in the recording layer, in addition to the above-mentioned color formers, for example, the following known color formers are used. Agents. Activated clay; attapulgite; colloidal silica; inorganic acid substances such as aluminum silicate, 4-cumylphenol; hydroquinone monobenzyl ether; 4,4'-isopropylidenediphenol; 1,1-bis (4-hydroxyphenyl) cyclohexane; 4,4'-dihydroxydiphenyl-2,2-
Butane; 4,4'-dihydroxydiphenylmethane;
2,2-bis (4-hydroxyphenyl) -4-methylpentane; 2,2-bis (4-hydroxyphenyl) heptane; bis (4-hydroxyphenylthioethoxy)
Methane; 1,5-di (4-hydroxyphenylthio)-
3-oxapentane; 1,1-bis (4-hydroxyphenyl) -1-phenylethane; 1,4-bis [α-methyl-α- (4'-hydroxyphenyl) ethyl] benzene; 1,3-bis [Α-Methyl-α- (4′-hydroxyphenyl) ethyl] benzene; 4,4′-dihydroxydiphenyl sulfide; bis (4-hydroxy-3
-Methylphenyl) sulfine; benzyl 4-hydroxybenzoate; butyl bis (p-hydroxyphenyl) acetate; methyl bis (p-hydroxyphenyl) acetate; (4
-Hydroxyphenylthio) acetic acid-2- (4-hydroxyphenylthio) ethyl ester; di (p-hydroxyphenylthioethyl) ether; N, N'-di-m-chlorophenylthiourea; N- (phenoxyethyl)- Four
-Phenolic compounds such as hydroxyphenyl sulfonamide, 4- [3- (p-tolylsulfonyl) propyloxy] salicylic acid; 4- [2- (p-methoxyphenoxy) ethyloxy] salicylic acid; 5- [p- (2- p
-Methoxyphenoxyethoxy) cumyl] salicylic acid;
Aromatic carboxylic acids such as p-chlorobenzoic acid; and zinc of these aromatic carboxylic acids; magnesium; aluminum; calcium; titanium; manganese; tin; salts with polyvalent metals such as nickel; and antipyrine of zinc thiocyanate Examples include organic acidic substances such as complexes.

In the heat-sensitive recording material of the present invention, a sensitizer can be added to the recording layer according to the purpose. Specific examples of the sensitizer include stearic acid amide and methoxycarbonyl-.
N-stearic acid benzamide, N-benzoylstearic acid amide, N-eicosanoic acid amide, ethylenebistearic acid amide, behenic acid amide, methylenebisstearic acid amide, N-methylolstearic acid amide,
Dibenzyl terephthalate, dimethyl terephthalate, dioctyl terephthalate, benzyl p-benzyloxybenzoate, phenyl 1-hydroxy-2-naphthoate, dibenzyl oxalate, oxalate-di-p-methylbenzyl,
Oxalic acid-di-p-chlorobenzyl, 2-naphthylbenzyl ether, m-terphenyl, p-benzylbiphenyl, tolylbiphenyl ether, di (p-methoxyphenoxyethyl) ether, 1,2-di (3-methylphenoxy). ) Ethane, 1,2-di (4-methylphenoxy) ethane, 1,2-di (4-methoxyphenoxy) ethane, 1,2-di (4-chlorophenoxy) ethane,
1,2-diphenoxyethane, 1- (4-methoxyphenoxy) -2- (2-methylphenoxy) ethane, p-
Methylthiophenyl benzyl ether, 1,4-di (phenylthio) butane, p-acetotoluidide, p-acetophenetide, N-acetoacetyl-p-toluidine, di (β-biphenylethoxy) benzene, p-di (vinyloxy) Examples include ethoxy) benzene and 1-isopropylphenyl-2-phenylethane. The amount of these sensitizers used is not particularly limited, but it is generally desirable to adjust the amount within the range of about 4 parts by weight or less relative to 1 part by weight of the color developing agent.

Further, a preservative improving agent may be used in combination so as to further enhance the preservability of the recorded image depending on the purpose as long as the effect is not impaired. Specific examples of such a storability improver include, for example, 1,4-diglycidyloxybenzene,
Epoxy compounds such as 4,4'-diglycidyloxydiphenyl sulfone, diglycidyl terephthalate, and bisphenol A type epoxy resin, 2,2'-methylenebis (4
-Methyl-6-tert-butylphenol), 2,2'-
Methylenebis (4-ethyl-6-tert-butylphenol), 2,2'-ethylidenebis (4,6-di-tert-
Butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), 4,4'-thiobis (2-methyl-6-tert-butylphenol), 4,
4'-butylidene bis (6-tert-butyl-m-cresol), 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,1,
3-tris (2-methyl-4-hydroxy-5-tert-
Butylphenyl) butane, 4,4'-thiobis (3-methylphenol), 4,4'-dihydroxy-3,
3 ', 5,5'-tetrabromodiphenyl sulfone,
4,4'-dihydroxy-3,3 ', 5,5'-tetramethyldiphenyl sulfone, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-
Hindered phenol compounds such as bis (4-hydroxy-3,5-dichlorophenyl) propane and 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 1- [α-methyl-α- (4 '-Hydroxyphenyl) ethyl] -4- [α', α'-bis (4 "-hydroxyphenyl) ethyl] benzene, N, N'-di-2-
Examples thereof include naphthyl-p-phenylenediamine and 2,2'-methylenebis (4,6-di-tert-butylphenyl) sodium phosphate.

In order to prepare a coating liquid for a recording layer containing these substances, water is generally used as a dispersion medium, and a basic dye, a coloring agent, and further a basic dye, a coloring agent, and the like are required by a stirrer / pulverizer such as a ball mill, attritor, or sand mill. A sensitizer or the like added according to the above is dispersed together or separately to prepare a coating liquid.
In such a coating liquid, starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, arabic gum, polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer are used as adhesives. A polymer salt, an ethylene / acrylic acid copolymer salt, a styrene / acrylic acid copolymer salt, a styrene / butadiene copolymer emulsion or the like is used in an amount of 10 to 40% by weight, preferably about 15 to 30% by weight of the total solid content. To be

It is also possible to use various pigments in combination in the coating liquid, for example, kaolin, clay, calcium carbonate, calcined clay, calcined kaolin, titanium oxide, diatomaceous earth,
Inorganic pigments such as fine particulate anhydrous silica and activated clay, styrene microballs, nylon powder, polyethylene powder, urea / formalin resin filler, and organic pigments such as raw starch particles can be used.

Furthermore, various auxiliaries can be added to the coating liquid, for example, sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, sodium salt, alginate, fatty acid metal salt and the like. Dispersant, benzophenone type,
Examples thereof include UV absorbers such as triazole type, defoaming agents, fluorescent dyes, and coloring dyes.

In the present invention, the method of forming the heat-sensitive recording layer is not particularly limited, and the heat-sensitive recording layer can be formed according to a conventionally well-known technique, for example, air knife coating, varibar blade coating, pure blade coating. It can be formed by a method of coating and drying the coating liquid on the support by short dwell coating, curtain coating or the like. The coating amount of the coating liquid is also not particularly limited, and is usually ² to 12 g / m ² in dry weight, preferably 3 to 10 g.
The range is / m ² . As the support, paper, synthetic paper, plastic film or the like is appropriately selected and used.

In the present invention, it is possible to further improve the storability of a recorded image by providing a resin layer on the heat-sensitive recording body and / or on the back side thereof, if necessary.
Further, in the field of heat-sensitive recording material manufacturing, such as providing an undercoat layer on the support to improve image quality and sensitivity, processing the back surface of the recording material into an adhesive label by processing with an adhesive, and providing a magnetic layer on the back surface of the recording material. Various known techniques can be added. Further, the image quality and the image density can be improved by performing a super calendering process after forming the recording layer.

[0017]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In addition, "part" and "%" in an example show "weight part" and "weight%", respectively, unless there is particular notice.

Example 1 Preparation of solution A 3- (N-ethyl-N-ethoxypropylamino) -6
A composition consisting of 10 parts of -methyl-7-anilinofluorane, 5 parts of a 5% aqueous solution of methyl cellulose, and 40 parts of water was pulverized with a sand mill until the average particle size became 1.5 µm. Preparation of Solution B A composition consisting of 30 parts of 2,4′-dihydroxydiphenyl sulfone, 5 parts of a 5% aqueous solution of methylcellulose, and 80 parts of water was pulverized with a sand mill until the average particle diameter became 1.5 μm. Preparation of liquid C A composition consisting of 20 parts of 1,2-di (3-methylphenoxy) ethane, 5 parts of a 5% aqueous solution of methylcellulose, and 55 parts of water was pulverized with a sand mill until the average particle diameter became 1.5 μm. Preparation of solution D 4-benzyloxy-4 '-(2-methyl-2,3-epoxypropyloxy) diphenyl sulfone 10 parts, 5% 5% aqueous solution of methylcellulose, and 40 parts of water It was pulverized until the diameter became 1.5 μm. Formation of recording layer 55 parts of solution A, 115 parts of solution B, 80 parts of solution C, 55 parts of solution D,
A recording layer coating liquid obtained by mixing and stirring 160 parts of a 10% polyvinyl alcohol aqueous solution and 25 parts of calcium carbonate,
45 g / m ² of high-quality paper coated on one side with a coating amount of 4 g /
A recording layer was formed by coating and drying so that the recording layer had a thickness of m ² .

Example 2 In the preparation of solution B, the heat-sensitivity was the same as in Example 1 except that 30 parts of 4,4'-isopropylidenediphenol was used in place of 30 parts of 2,4'-dihydroxydiphenylsulfone. I got a record.

Example 3 In the same manner as in Example 1 except that 30 parts of 4-hydroxy-4'-isopropoxydiphenyl sulfone was used in place of 30 parts of 2,4'-dihydroxydiphenyl sulfone in the preparation of the liquid B. A thermosensitive recording material was obtained.

Example 4 A thermosensitive recording medium was prepared in the same manner as in Example 1 except that 2-naphthylbenzyl ether 20 was used in place of 20 parts of 1,2-di (3-methylphenoxy) ethane in the preparation of solution C. Got

Example 5 Preparation of Liquid G A composition comprising 100 parts of calcined clay [trade name: Ansilex, manufactured by EMC, oil absorption: 110 ml / 100 g], 100 parts of a 10% aqueous solution of polyvinyl alcohol, and 200 parts of water was prepared. By mixing and stirring, a coating liquid for the undercoat layer was obtained. On one surface of woodfree paper of Preparation 45 g / m ² of the heat-sensitive recording material, after coating and drying the solution G so that the coating amount after drying of 8 g / m ^2, coating the recording layer was prepared as in Example 1 Coating amount after drying is 4 g /
After coating and drying so as to be m ² , super calender treatment was carried out to obtain a heat-sensitive recording material.

Example 6 Same as Example 1 except that 30 parts of bis (3-allyl-4-hydroxyphenyl) sulfone was used in place of 30 parts of 2,4'-dihydroxydiphenylsulfone in the preparation of solution B. A thermosensitive recording medium was obtained.

Comparative Example 1 In the preparation of solution A, 3- (N-ethyl-N-ethoxypropylamino) -6-methyl-7-anilinofluorane was replaced with 10 parts of 3-di (n-butyl) amino-. Except that 10 parts of 6-methyl-7-anilinofluorane were used,
A thermal recording material was obtained in the same manner as in Example 1.

Comparative Example 2 In preparation of solution A, 3- (N-ethyl-N-isoamyl was used instead of 10 parts of 3- (N-ethyl-N-ethoxypropylamino) -6-methyl-7-anilinofluorane. A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 10 parts of amino) -6-methyl-7-anilinofluorane was used.

Comparative Example 3 4-benzyloxy-4 '-(2-
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 10 parts of 1,4-diglycidyloxybenzene was used instead of 10 parts of methyl-2,3-epoxypropyloxy) diphenylsulfone.

Comparative Example 4 55 parts of A solution, 115 parts of B solution, 80 parts of C solution, 160 parts of 10% polyvinyl alcohol aqueous solution in the formation of the recording layer,
And a recording layer coating solution obtained by mixing and stirring 25 parts of calcium carbonate, the coating dried to a recording layer as the coating amount after drying on one surface of woodfree paper of 45 g / m ² is 4g / m ² Formed. The 10 types of heat-sensitive recording materials thus obtained were subjected to the following evaluation tests, and the results are shown in [Table 1].

1. [Whiteness] To evaluate the degree of color fog, the whiteness of the recording layer was measured with a Hunter whiteness meter.

2. [Coloring Density] Each thermal recording material was colored with an applied voltage of 24 V and a pulse time of 2 ms by using a thermal recording material evaluation device [TH-PMD, manufactured by Okura Electric Co., Ltd.] to obtain a recorded image. The color density was measured in a visual mode with a Macbeth densitometer [RD-914 type, manufactured by Macbeth Co.].

3. [Plasticizer resistance] A vinyl chloride wrap film (manufactured by Mitsui Toatsu Kagaku Co., Ltd.) was triple-wrapped on a polypropylene pipe (40 mmφ pipe),
A heat-sensitive recording material on which print color was developed was sandwiched so that the print color surface was on the outside, and a vinyl chloride wrap film was further wound three times over it, and the print density after leaving at 20 ° C. for 24 hours and 40 The plasticizer resistance was evaluated from the print density after standing at 24 ° C. for 24 hours. [Evaluation Criteria] The evaluation criteria of the plasticizer resistance are as follows. ◎ −−−−− ○ −−−−− △ −−−−− × Excellent Excellent Inferior

[0031]

[Table 1]

[0032]

As is clear from the results of [Table 1], each of the thermosensitive recording materials of the present invention has little background fog, is excellent in the storability of the recorded image on the plasticizer, and is also excellent in the recording sensitivity. It was a thermosensitive recording medium.

Claims (2)

[Claims] 1. A thermosensitive recording medium comprising a support and a recording layer containing a colorless or light-colored basic dye and a coloring agent, wherein 3- (N-ethyl-N-ethoxypropyl) is contained in the recording layer. A heat-sensitive recording material containing amino) -6-methyl-7-anilinofluorane and 4-benzyloxy-4 '-(2-methyl-2,3-epoxypropyloxy) diphenyl sulfone. 2. In the recording layer, 4,4'-dihydroxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone and 4-hydroxy 4'- are used as a coloring agent. Benzyloxydiphenyl sulfone, bis (3-allyl-4)
The heat-sensitive recording material according to claim 1, which contains at least one of -hydroxyphenyl) sulfone.