JPS61108582A - Thermal recording body - Google Patents

Abstract

PURPOSE:To make the retentivity of a printed character excellent and to prevent the generation of color development fog in a recording layer, by providing a resin layer based on a water-soluble high-molecular compound on a thermal recording layer containing a fluorane compound as a color forming agent and a diphenylsulfone derivative as a coupler. CONSTITUTION:As a fluorane compound represented by general formula [I], 3-diethylamino-7-(o-fluoroanilino)fluorane and 3-dibutylamino-7-(o-fluoroanilino) fluorane are especially designated and used as a color forming agent. At least one compound selected from a diphenylsulfone derivative and 4,4'- cyclohexylidene diphenol represented by general formula [II] is used as a coupler. The coupler is used in an amount of 1-50pts.wt. of the color forming agent end a sensitizer is added if necessary. In the preparation of a coating solution, water is generally used as a dispersing medium and a binder is contained in the coating solution in usual. A resin layer based on a water-soluble high-molecular compound is provided on thus formed recording layer.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to a heat-sensitive recording medium, and particularly to a heat-sensitive recording medium with excellent storage stability.

"Prior Art" Conventionally, heat-sensitive recording utilizes a coloring reaction between a coloring agent and a coloring agent that develops color when it comes into contact with the coloring agent, and brings a recoloring substance into contact with heat to obtain a colored image. The body is well known. Such heat-sensitive recording media are relatively inexpensive, and the recording devices are compact and relatively easy to maintain, so they are used not only as recording media for facsimiles and various computers, but also in a wide range of fields.

One of the fields of use is POS (PoS) in retail stores etc.
(int of 5ales) With the expansion of systemization, its use as a label is increasing.

However, such heat-sensitive recording materials generally have water resistance, oil resistance,
Because of its poor plasticizer resistance, for example, if water, oil, oil, or plasticizers contained in plastic films come into contact with the colored print, the print density will drop significantly, and heat-sensitive recording may occur during handling. There is a drawback that when the layer is touched with the hand, a fingerprint-like fog appears.

As a method to eliminate such drawbacks, there is a method of coating an aqueous emulsion of a resin having film-forming ability and chemical resistance on the heat-sensitive recording layer (Japanese Patent Application Laid-open No. 128347-1982).
, a method of applying a water-soluble polymer compound such as polyvinyl alcohol (Utility Model Application Publication No. 56-125354), and the like have been proposed.

However, even for heat-sensitive recording materials with a resin layer on the recording layer, there are cases where long-term plasticizer resistance or oil resistance is required, or water resistance and plasticizer resistance called water plasticizer resistance are required. When both are required at the same time, or under extremely severe conditions where both humidity and temperature are involved, defects such as decreased print density are associated.

Furthermore, coating a water-soluble polymer compound on the recording layer may cause color fogging on the recording layer.

"Problems to be Solved by the Invention" An object of the present invention is to provide a heat-sensitive recording material that has excellent print retention even under severe conditions and does not cause color fogging on the recording layer. This object is achieved by selectively using specific coloring agents and coloring agents as described below, and by providing a resin layer on the recording layer.

At least one oran compound;
s each represents a hydrogen atom, a halogen atom, a methyl group, an ethyl group, or a nitro group. ] A diphenylsulfone derivative represented by the following general formula (II) as a coloring agent and g
4. A heat-sensitive recording material characterized in that a resin layer containing a water-soluble polymer compound as a main component is provided on a heat-sensitive recording layer containing at least one selected from 4'-cyclohexylidene diphenol. It is.

R60Rq [In the formula, Rh, R? , Rs each represent a hydrogen atom, a halogen atom, a lower alkyl group, an alkoxyl group, an aryloxyl group or a benzyloxy group, and R9 represents a hydrogen atom or a hydroxyl group. [Effect] In the present invention, specific examples of the fluoran compound represented by the general formula (I) include 3-diethylamino-7
-(0-fluoroanilino)fluoran 3-diethylamino-7-(p~fluoroanilino)fluoran 3-diethylamino-6-methyl-7-(p-fluoroanilino)fluoran 3-diethylamino-7-(2'-Methyl-5'-fluoroanilino)fluoran 3-diethylamino-? -(2'-chloro-4'-fluoroanilino)fluoran 3-diethylamino-7-(m-fluoroanilino)fluoran 3-diethylamino-7-(2'-fluoro-5'-nitroanilino)fluoran 3-diethylamino -7-(2',4'-difluoroanilino)fluoran 3-dibutylamino-7-(0-fluoroanilino)fluoran and the like may be mentioned, but of course two or more of these may be used in combination. Among these fluoran compounds, 3-
Diethylamino-7-(o-fluoroanilino)fluoran and 3-diptylamino-7-(0-fluoroanilino)fluoran are more preferably used because they provide the desired effects of the present invention.

The present invention is characterized in that a specific fluoran compound as described above is contained in the recording layer as a coloring agent, but if necessary, various known colorless or light-colored compounds may be used as long as they do not impede the effects of the present invention. A basic dye may be used in combination. Examples of such known basic dyes include the following.

3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3,3-bis(p-dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl)-3-(1,2 -dimethylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(2-methylindol-3-yl)phthalide, 3,3-andsu(1,2-dimethylindole-
3-yl)-5-dimethylaminophthalide, 3,3-bis(1゜2-dimethylindol-3-yl)-6-dimethylaminophthalide, 3,3-bis(9-ethylcarbazol-3- yl)-6-dimethylaminophthalide,
3.3-bis(2-phenylindo-(ru-3-yl)
-6-dimethylaminophthalide, 3-p-dimethylaminophenyl-3-(1-methylpyrrol-3-yl)-
Triallylmethane dyes such as 6-dimethylaminophthalide, 4,4'- and su-dimethylaminobenzhydrylbenzyl ether, N-halophenyl-leucoauramine, N-2,4,5-)lichlorophenylleugo , diphenylmethane dyes such as t-lamin, thiazine dyes such as benzoylleucomethylene blue and p-nitrobenzoylleucomethylene blue, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-
Phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho(6'-methoxybenzo)spiropyran, 3-propyl-spiro-
Spiro dyes such as dibenzopyran, lactam dyes such as rhodamine-B-anilinolactam, rhodamine (p-nitroanilino) lactam, rhodamine (0-chloroani+7)) lactam, 3-dimethylamino-7-methoxyfluoran, 3-diethylamino-6-methoxyfluorane, 3-diethylamino-7-methoxyfluoran, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3
-diethylamino-6,7-dimethylfluorane, 3-
(N-ethyl-1)-)luidino)-7-methylfluorane, 3-diethylamino-7-N-acetyl-N-
Methylaminofluorane, 3-diethylamino-7-N
-Methylaminofluorane, 3-diethylamino-7-
Dibenzylaminofluorane, 3-diethylamino-7
-N-methyl-N-benzylaminofluorane, 3-diethylamino-7-N-chloroethyl-N-methylaminofluorane, 3-diethylamino-7-N-diethylaminofluorane, 3-(N-ethyl-p- ) luidino)-6-methyl-7-phenylaminofluorane, 3-
(N-ethyl-p-)luidino)-6-methyl-7-(
p-1luidino)fluoran, 3-diethylamino-6
-Methyl-7-phenylaminofluorane, 3-diethylamino-7-(2-carbomethoxy-phenylamino)fluoran, 3-(N-ethyl-N-1so-amylamino)-6-methyl-7-phenylaminofluoran Oran, 3-(N-cyclohexyl-N-methylamino)-
6-methyl-7-phenylaminofluorane, 3-pyrrolidino-6-methyl-7-phenylaminofluorane,
3-Piperidino-6-methyl-7-phenylaminofluorane, 3-diethylamino-6-methyl-7-xylidinofluorane, 3-diethylamino-7-(o-chlorophenylamino)fluorane, 3-dibutylamino-
Fluoran dyes such as 7-(o-chlorophenylamino)fluoran and 3-pyrrolidino-6-methyl-7-p-butylphenylaminofluoran.

In addition, when using the above-mentioned specific fluoran compound and other basic dye together as a coloring agent, the mixing ratio should be selected appropriately depending on the quality objective, the type of basic dye, etc. It is desirable to use the compound in an amount of at least 10% by weight, preferably 50% by weight or more, based on the total color former.

In the present invention, examples of the diphenylsulfone derivative represented by the general formula (n) include the following.

4-hydroxy-diphenylsulfone 4-hydroxy-4'-chlorodiphenylsulfone 4-hydroxy-4'-fluorodiphenylsulfone 4-hydroxy-4'-methyldiphenylsulfone 4-hydroxy-4'-isopropyldiphenylsulfone 4-hydroxy- 2', 4', 6'-) Listyl diphenyl sulfone 4-hydroxy-2'-methyl-4'-chlorodiphenyl sulfone 4-hydroxy-2', 4'-dichlorodiphenyl sulfone 4-hydroxy-4'-methoxy Diphenylsulfone 4-hydroxy-4'-isopropyloxydiphenylsulfone 4-hydroxy-4'-butoxydiphenylsulfone 4-hydroxy-4'-octyloxydiphenylsulfone 4-hydroxy-4'-benzyloxydiphenylsulfone 2,4-dihydroxy -Diphenylsulfone 2,4-dihydroxy-4'-methyldiphenylsulfone In the present invention, at least one selected from the diphenylsulfone derivative represented by the general formula (II) and 4,4'-cyclohexylidene diphenol is used. Among these coloring agents, 4-hydroxy-4'-chlorodiphenyl sulfone,
4-Hydroxy-4'-methyldiphenylsulfone, 4
-Hydroxy-4'-isopropyloxydiphenylsulfone, 4-hydroxy-4'-butoxydiphenylsulfone, and 4,4'-cyclohexylidene diphenol are particularly preferably used because the desired effects of the present invention can be efficiently obtained. It will be done.

Note that the ratio of the color former to the color former in the recording layer is appropriately selected depending on the color former used and the type of color former, and is not particularly limited, but in general, 1 weight of the color former is 1 to 50 parts by weight, preferably 2 to 10 parts by weight, of the coloring agent is used.

In the heat-sensitive recording material of the present invention, an aggravating agent may be added to the recording layer as necessary. Various substances are known as sensitizers, such as stearic acid amide,
Stearic acid methylenebisamide, oleic acid amide,
Fatty acid amides such as palmitic acid amide and coconut fatty acid amide, terephthalic acid dibenzyl ester, 1,2-di(
3-methylphenoxy)ethane, 1,2-diphenoxyethane, 2,2'-methylenebis(4-methyl-6-t
-butylphenol), 4,4'-butylidene bis(6
-t-butyl-3-methylphenol), 1,1.3-
) Hindered phenols such as lis(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 2-(
Examples include ultraviolet absorbers such as 2'-hydroxy-5'-methylphenyl)benzotriazole and 2-hydroxy-4-benzyloxybenzophenone, and various known thermofusible substances.

The amount of the sensitizer added is not particularly limited, and is generally 0.05 to 5 parts by weight per 1 part by weight of the basic dye.
It is used in an amount of 0 parts by weight, preferably in the range of 0.2 to 5 parts by weight.

To prepare a coating solution containing these substances, the coloring agent and the coloring agent are generally dispersed together or separately using water as a dispersion medium, stirring with a ball mill, attritor, sand grinder, etc., or using a pulverizer, and then coating. Prepared as a liquid. Such coating liquids usually contain starches, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, loin, gelatin, casein, gum arabic, polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, and diisobutylene/maleic anhydride. Copolymer salt, styrene/maleic anhydride copolymer salt, ethylene/
Acrylic acid copolymer salt, styrene/acrylic acid copolymer salt, styrene/butadiene copolymer emulsion, urea resin, melamine resin, amide resin, etc. have a total solid content of 10
It is used in an amount of from 70% by weight, preferably from 15 to 50% by weight.

Furthermore, various auxiliary agents can be added to the coating liquid.

For example, sodium dioctyl sulfosuccinate,
Dispersants such as sodium dotecylbenzenesulfonate, sodium lauryl alcohol sulfate, fatty acid metal salts, ultraviolet absorbers such as benzophenone,
Other examples include antifoaming agents, fluorescent dyes, and colored dyes.

Also, if necessary, waxes such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, and ester wax, kaolin, clay, talc, and charcoal can be used! Inorganic pigments such as calcium acid, calcined clay, titanium oxide, diatomaceous earth, fine particulate anhydrous silica, and activated clay may also be added.

In the heat-sensitive recording material of the present invention, there are no particular limitations on the method of forming the recording layer, and the recording layer can be formed according to conventionally well-known techniques, such as applying a coating liquid by air knife coating, blade coating, etc. - Formed by drying methods, etc. The amount of coating liquid to be applied is also not particularly limited, but it is usually 2 to 12 g/m in terms of dry weight, preferably 3 to Log
/d range.

As described above, the heat-sensitive recording material of the present invention is provided with a resin layer containing a water-soluble polymer compound as a main component on the thus formed recording layer. , carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, starch and its derivatives, casein, sodium alginate, polyvinylpyrrolidone, polyacrylamide, styrene-maleic acid copolymer salt, polyurethane resin, Examples include urea resin and melamine resin. Among these water-soluble polymer compounds, acetoacetyl group-modified polyvinyl alcohol is particularly preferably used because it yields a heat-sensitive recording material with particularly excellent print retention.

Incidentally, a pigment may be added to the resin layer in the present invention, if necessary, in order to improve printing permeability and sticking.

Specific examples of such pigments include calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, silicon dioxide, aluminum hydroxide, barium sulfate, zinc sulfate, talc,
Examples include inorganic pigments such as kaolin, clay, calcined clay, and colloidal silica, organic pigments such as styrene microballs, nylon powder, polyethylene powder urea/formalin resin filler, and raw starch granules. The amount used is generally 5 parts by weight per 100 parts by weight of the resin component.
It is desirable that the content be in the range of 500 parts by weight.

Furthermore, in the coating liquid, lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, and ester wax, surfactants such as sodium dioctyl sulfosuccinate (as dispersants and wetting agents), Various auxiliary agents such as antifoaming agents can also be added as appropriate.

In the present invention, the coating liquid forming the protective layer is generally prepared as an aqueous coating liquid, and if necessary, it is thoroughly mixed and dispersed using a mixing/stirring machine such as a mixer, attritor, ball mill, or roll mill. It is applied onto the heat-sensitive recording layer by a device.

The coating amount of the protective layer coating liquid is not particularly limited, but if it is less than 0.1 g/ryf, the desired effect of the present invention cannot be sufficiently obtained, and if it exceeds 20 glcd, the thermal recording material There is a risk that the recording sensitivity of
Generally, dry weight is 0.1~20g/! 1 Preferably adjusted within the range of 0.5 to 10 g/rrr) Awa! (
7) No, no.

Thus, in the heat-sensitive recording material of the present invention, a specific coloring agent and a coloring agent are selectively used, and a resin layer is provided on the recording layer, so that no color development or fading occurs, and moreover, it is difficult to use under harsh conditions. It has excellent print retention even under various conditions.

Note that, if necessary, it is also possible to further improve the storage stability by providing a protective layer on the back side of the heat-sensitive recording material. Furthermore, various known techniques in the field of heat-sensitive recording material production may be added as necessary, such as providing an undercoat layer on the support, applying an adhesive treatment to the back surface of the recording material, and processing it into an adhesive label.

The present invention will be described in more detail with reference to Examples below, but it is of course not limited thereto.

Note that parts and % in the examples indicate parts by weight and % by weight, respectively, unless otherwise specified.

"Example" Example 1 ■ Preparation of liquid A 3-dibutylamino-7-(o-fluoroanilino)fluoran 10 parts Methylcellulose 5
% aqueous solution 5 parts water
40 parts of this composition was ground to an average particle size of 3 μm using a sand grinder.

■ Preparation of B solution 4.4'-Cyclohexylidene diphenol 20 parts Methyl cellulose 5% aqueous solution 5 parts water
55 parts of this composition was ground to an average particle size of 3 μm using a sand grinder.

■C? & Preparation Stearic acid amide 20 parts Methyl cellulose 5% aqueous solution 5 parts Water
55 parts of this composition was ground to an average particle size of 3 μm using a sand grinder.

(2) Formation of Recording Layer 55 parts of liquid A, 80 parts of liquid B, 80 parts of liquid C, and 50 parts of a 15% polyvinyl alcohol aqueous solution were mixed and stirred to prepare a coating liquid.

The obtained coating liquid was applied to a base paper of 50 g/rrr so that the coating amount after drying was 6 glcd and dried to obtain a heat-sensitive recording paper.

■ Formation of resin layer 10% aqueous solution of acetoacetyl group-modified polyvinyl alcohol (Goseheimer Z-200, manufactured by Nippon Gosei Kagaku Co., Ltd.)
00 parts, 20 parts of calcium carbonate, and 50 parts of water were mixed and stirred to prepare a coating liquid. The resulting coating liquid was applied onto the recording layer of the heat-sensitive recording paper so that the coating amount after drying was 6 glcd, and dried to form a resin layer.

Examples 2 to 4 In Bi1M composition, 4-hydroxy-4'-methyldiphenylsulfone (Example 2), 4-hydroxy-4 instead of 4,4'-cyclohexylidene diphenol
'-Chlorodiphenylsulfone (Example 3) and 4-
A thermosensitive recording paper having three types of resin layers was obtained in the same manner as in Example 1 except that 20 parts of hydroxy-4'-isopropyloxydiphenyl sulfone (Example 4) was used.

Example 5 In preparing Solution A, instead of 10 parts of 3-dibutylamino-7-(O-fluoroanilino)fluorane, 8 parts of 3-dibutylamino-7-(0-fluoroanilino)fluorane and 3- A thermosensitive recording paper having a sludge layer was obtained in the same manner as in Example 1 except that a mixture with 2 parts of (N-ethyl-p-toluidino)-6-methyl-7-phenylaminofluorane was used.

Example 6 In the coating liquid for resin layer formation, 10 parts of polyvinyl alcohol (PVA-110° manufactured by Kuraray Co., Ltd.) was used instead of 100 parts of acetoacedel group-modified polyvinyl alcohol aqueous solution.
A thermosensitive recording paper having a resin layer was obtained in the same manner as in Example 1 except that 100 parts of the % aqueous solution was used.

Comparative Examples 1 to 2 In preparing liquid A, 3-dibutylamino-7-1 (0-
3-dibutylamino-7-(o-chlorophenylamino)fluoran (Comparative Example 1) and 3-(N-ethyl-p-+-luidino)-6-methyl-7-phenyl instead of fluoroanilino)fluoran A thermosensitive recording paper having two types of resin layers was obtained in the same manner as in Example 1, except that 10 parts of each aminofluorane (Comparative Example 2) was used.

Comparative Example 3 In preparing liquid A of Example 3, 3-dibutylamino-7
-(0-fluoroanilino)fluorane instead of 3
-dibutyl 7 minnow 7-(0-chlorophenylamino)
A thermosensitive recording paper having a resin layer was obtained in the same manner as in Example 3 except that 10 parts of fluorane was used.

Comparative Example 4 A thermosensitive recording material having a resin layer was prepared in the same manner as in Example 1 except that 20 parts of 4.4'-isopropylidene diphenol was used instead of 4.4'-cyclohexylidene diphenol in preparing liquid B. Got paper.

Comparative Example 51 In preparing liquid A, 3-dibutylamino-7-(o-chlorophenylamino)fluoran 1 was used instead of 3-dibutylamino-7-(0-fluoroanilino)fluoran.
Using 0 parts, and further in the B111l composition, 4.4'-
Example 1 except that 20 parts of benzyl 4-hydroxybenzoate was used instead of cyclohexylidene diphenol.
A thermosensitive recording paper having a resin layer was obtained in the same manner as above.

For the 11 types of heat-sensitive recording papers thus obtained, in order to evaluate the degree of color fogging, the whiteness of the recording layer was measured using a Hunter whiteness meter, and the results are shown in Table 1.

Next, these thermal recording papers were printed using a thermal printer, and the printed color density was measured using a Macbeth densitometer (Macbeth Co., Model RD-100R). The results are shown in Table 1. In addition, regarding the thermal recording paper after such printing,
Plasticizer resistance and temperature/humidity suitability were evaluated by the following methods, and the results are listed in Table 1.

Plasticizer resistance: Wrap vinyl chloride lamp film (manufactured by Mitsui Toatsu Co., Ltd.) three times around a polypropylene pipe (40mmφ tube), and then place heat-sensitive recording paper with colored print on it so that the colored side of the print is on the outside. A vinyl chloride wrap film was then wrapped three times over the paper using scissors, and the plasticizer resistance was evaluated from the print density after 72 hours.

◎: Very good ○: Good △: Slightly poor ×: Poor Temperature and humidity suitability: 50″C290%R thermal recording paper after printing
After being left in an H atmosphere for 24 hours, temperature and humidity suitability was evaluated from the print density.

◎: Extremely good ○: Good △: Slightly poor ×: Poor Table 1 "Effect" As is clear from the results in Table 1, 1 according to the present invention
The heat-sensitive recording material did not cause color fogging and had excellent printing stability even under severe conditions.

Claims (1)

[Claims] (1) At least one fluoran compound represented by the following general formula [I] as a coloring agent, and ▲a mathematical formula, a chemical formula, a table, etc.▼[I] [In the formula, R_1 and R_2 are each a hydrogen atom or a lower alkyl group, R_3 is a hydrogen atom or a methyl group, R
_4 and R_5 each represent a hydrogen atom, a halogen atom, a methyl group, an ethyl group, or a nitro group. ] A water-soluble polymer compound as a main component is placed on a heat-sensitive recording layer containing a diphenylsulfone derivative represented by the following general formula [II] as a coloring agent and at least one selected from 4,4'-cyclohexylidene diphenol. A heat-sensitive recording material characterized by being provided with a resin layer. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [II] [In the formula, R_6, R_7, and R_8 are hydrogen atoms, respectively.
R_9 represents a halogen atom, a lower alkyl group, an alkoxyl group, an aryloxyl group, or a benzyloxy group, and R_9 represents a hydrogen atom or a hydroxyl group. ]