JPH04135784A - Thermal recording material - Google Patents

Abstract

PURPOSE:To make the title thermal recording material high in sensitivity and excellent in raw shelf property and stability of a coloring image by a method wherein 4-hydroxy-4-isopropoxydiphenyl sulfone is contained in a thermal coloring layer for a thermal recording material composed by providing the thermal coloring layer containing an electron donative colorless dye and an electron acceptive compound on a base material, and the compound as expressed by the formula is contained as the electron donative colorless dye. CONSTITUTION:2-Anilino-3-methyl-6-N-methyl-N-tetrahydrofurfurylaminofl uoran or the like is as an example of the compound to be expressed by the formula and triphenylmethane phthalide compound or the like is as an example of an electron donative colorless dye. The electron donative colorless dye, electron acceptive compound, and sensitizer together with water soluble high molecular aquous solution of polyvinyl alcohol or the like are dispersed to several micron or under by using a ball mill, a sand mill, etc., and a thermal applicable liquid is prepared by adding pigment, surface active agent, binder, metal soap, wax, antioxidant, ultraviolet absorption agent, etc., if necessary. Thereby, very excellent performance which is good in both heat resistance and light fastness can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a heat-sensitive recording material, and more particularly to an electron-donating colorless dye and an electron-donating colorless dye that have improved color development, shelf life, and stability of colored images. The present invention relates to a heat-sensitive recording material in which a coloring layer containing an electron-accepting compound is provided on a support.

(Prior Art) Recording materials using electron-donating colorless dyes and electron-accepting compounds are already well known as pressure-sensitive paper, thermal paper, light-sensitive pressure-sensitive paper, electrically conductive thermal recording paper, thermal transfer paper, and the like. For example, British Patent No. 2,140.449, U.S. Patent No. 4,48
No. 0.052, No. 4.436.920, Special Publication No. 1983
-23992, JP-A-57-179836, JP-A No. 60
-123556, 60-123557, etc. for details. In particular, heat-sensitive recording materials are detailed in Japanese Patent Publications No. 43-4160 and Japanese Patent Publication No. 45-14039.

These thermal recording systems are being applied in many fields such as facsimiles, printers, and labels, and the needs are expanding. However, heat-sensitive recording materials have the disadvantage of fogging caused by solvents, etc., and the disadvantage that the color-forming material causes discoloration due to oils, fats, chemicals, etc., so labels, etc.
In the fields of slips, word processor paper, plotter paper, etc., the value of products has been significantly diminished. The present inventors have determined the oil solubility, water solubility, 1 partition coefficient, pKa
We have pursued the development of good materials for recording materials and recording materials by focusing on the polarity of the base and the position of the substituents. However, by imparting these resistances, a problem has arisen in that sensitivity, light resistance, and heat resistance are significantly reduced.

(Objective of the Invention) An object of the present invention is to provide a heat-sensitive recording material which is highly sensitive and has good print quality in terms of storage stability and color image stability.

(Structure of the Invention) The object of the present invention is to provide a heat-sensitive recording material in which a heat-sensitive coloring layer containing an electron-donating colorless dye and an electron-accepting compound is provided on a support. 1. A heat-sensitive recording material comprising hydroxy-4'-isopropoxydiphenyl sulfone and, as the electron-donating colorless dye, a compound represented by the following general formula (1).

(R represents a lower furkyl group.) (2) The electron-donating colorless dye is 2-anilino-3-methyl-6-N-ethyl-N-tetrahydrofurfurylaminofluorane according to claim (1). heat-sensitive recording material.

achieved by.

The 4-hydroxy-4'-isopropoxydiphenyl sulfone according to the present invention generally does not easily fade, but has the characteristics of low sensitivity and poor light resistance.

However, it has been found that when the fluoran compound of the present invention is used, the sensitivity is specifically increased, the light resistance is good, and the image storage stability is high.

Specific examples of the compound represented by compound (1) according to the present invention include 2-anilino-3-methyl-6-N-methyl-N-tetrahydrofurfurylaminofluorane, 2-
Anilino-3-methyl-6-N-ethyl-N-tetrahydrofurfuryl 7minofluorane, 2-anilino-3-
Methyl-6-N-propyl-N-tetrahydrofurfurylaminofluorane, 2-anilino-3-methyl-6-
N-butyl-N-tetrahydrofurfurylaminofluorane, especially 2-anilino-3-methyl-6
-N-ethyl-N-tetrahydrofurfurylaminofluorane is preferred.

In the present invention, it is necessary that the compound [1] accounts for 50% by weight or more of the electron-donating colorless dye. Under the above-mentioned conditions, it can be used in combination with other electron-donating colorless dyes. Examples of electron-donating colorless dyes that can be used in combination are shown below.

Examples of electron-donating colorless dyes include triphenylmethane phthalide compounds, fluoran compounds, phenothiazine compounds, indolyl phthalide compounds, leucoolamine compounds, rhodamine lactam compounds, triphenylmethane compounds, There are various compounds such as triazene compounds, spiropyran compounds, and fluorene compounds. Specific examples of phthalides can be found in U.S. reissued patent specification cylinder 2.
3゜024, U.S. Patent Specification No. 3,491,111, U.S. Patent No. 3,491.112, U.S. Patent No. 3,491゜116
No. 3,509,174, and specific examples of fluorans are given in U.S. Pat.
, 627.787, 3.641.011, 3.462.828, 3.681.390, 3,920.510, 3,959,571 ,
Specific examples of spiropyrans can be found in U.S. Patent Specification No. 3,971.
No. 808, pyridine-based and pyrazine-based compounds are described in U.S. Pat.
, No. 869, No. 4,246,318, and specific examples of fluorene compounds are described in Japanese Patent Application No. 61-240989.

Among these, 2-7 arylamino-3-H, halogen-, alkyl-, or alkoxy-6-substituted aminofluorane which regenerates color is particularly effective.

Specific examples include 2-anilino-3-methyl-6-dibutyl-7minofluorane and 2-anilino-3-methyl-6-N-cyclohexyl-N-methylaminofluorane.

2-p-Chloroanilino-3-methyl-6-sibutylaminofluorane, 2-anilino-3-methyl-6-cyoctyl7minofluorane, 2-7 dilino-3-chloro-
6-ethylaminofluorane, 2-anilino-3-methyl-6-N-ethyl-N-isoamyl 7minofluorane, 2-anilino-3-methyl-6-N-ethyl-N-
Dodecylaminofluoran, 2-anilino-3-methoxy-6-cyptyl 7minofluoran, 2-0-chloroanilino-6-sibutylaminofluoran, 2-p-chloroanilino-3-ethyl-6-N-ethyl -N-isoamylaminofluorane, 2-〇-chloro7nilino6-
p-Butylanilinofluorane, 2-anilino-3-pentadecyl-6-ethylaminofluorane, 2-anilino-3-ethyl-6-sibutylaminofluorane, 2
-0-Toluidino-3-methyl-6-diitupropylaminofluorane, 2-anilino-3-methyl-6-N-
Inbutyl-N-ethylaminofluorane, 2-anilino-3-methyl-6-N-methyl-N-γ-ethoxypropylaminofluorane.

2-anilino-3-methyl-6-N-ethyl-N-γ-
Methoxypropyl 7minofluorane, 2-anilino-3
-Methyl-6-N-ethyl-N-γ-ethoxypropylaminofluorane, 2-7 dilino-3-methyl-6-N
-Ethyl-N-γ-propoxypropylaminofluorane, 2-anilino-3-chloro-6-N-ethyl-N-
Examples include isoamylaminofluorane.

The dispersed particle size of the 4-hydroxy-4'-impropoxydiphenyl sulfone according to the present invention after being atomized using a sand mill or the like is preferably 3 microns or less, preferably 2 microns or less in order to obtain a color sensitivity of 1.

In addition, the 4-hydroxy-4'-isopropoxydiphenylsulfone according to the present invention can be prepared from the already well-known 4-hydroxydiphenylsulfone compounds, salicylic acid derivatives, metal salts of aromatic carboxylic acids, phenol derivatives, phenolic resins, novolac resins, Electron-accepting compounds such as metal-treated novolak resins, metal complexes, acid clay, and hentonite may be used in combination.

Examples of these are Special Publication No. 9309 of 1972 and Special Publication No. 1 of 1973.
No. 4039, JP-A-52-140483, JP-A-48
-51510, JP-A-57-210886, JP-A-58-87089, JP-A-59-11286, JP-A-60-176795, JP-A-61-95988, etc.

Some examples of these include 4-tert-butylphenol, 4-phenylphenol, and 4-hydroxydiphenoxide-α-naphthol.

β-naphthol, hexyl-4-hydroxybenzoate, 2,2'-dihydroxybiphenyl.

2.2-bis(4-hydroxyphenyl)propane (bisphenol A), 4.4'-isopropylidenebis(2-methylphenol)I It l+-bis-(3-chloro-4-hydroxyfer)cyclohexane, 111 -bis(3-chloro-4-hydroxyphenyl)-2-ethylbutane.

4.4'-Secondary octylidene diphenol, 4-tert-octylphenol.

4+ 4'-5ee-butylidene diphenol, 4-
p-methylphenylphenol, 4.4'-isopentylidenephenol, 4.4'-methylcyclohexylidenediphenol, bis(3-7ly-4-hydroxyphenyl)sulfone, 4-hydroxyphenyl-
34 dimethylphenyl sulfone, 4-hydroxy-4'
-Propoxydiphenylsulfone, 4-hydroxy-4
'-Dithoxydiphenylsulfone, 4-hydroxy-4
'-Methoxydiphenylsulfone, 4-hydroxy-4
'-Methyldiphenylsulfone, 4-hydroxy-4'
-ethyldiphenylsulfone, 4-hydroxy-4'-
Improvir diphenyl sulfone, 4-hydroxy-4
'-Propyldiphenylsulfone, 4-hydroxy-4
'-Chlorodiphenylsulfone, 4-hydroxy-4'
-Florodiphenylsulfone, 4-hydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfide, 1,4-bis-(4'-hydroxycumyl)
Benzene, 1,3-bis-(4'-hydroxycumyl)
Benzene, 4.4'-thiobis(6-tert-butyl-3-methylphenol).

4.4'-Dihydroxydiphenylsulfone.

Human O-quinone monohensyl ether, 4-hydroxybenzophenone, 2,4-dihydroxybenzophenone,
Polyvinylbenzyloxyphenol, 2,
4.4'-hdihydroxybenzophenone, 2.2'
, 4.4'-tetrahydroxybenzophenone, 4
-Hydroxyphthalic acid.

Methyl dimethyl-4-hydroxybenzoate, 2°4.4
'-1 ~ lyhydroxydiphenyl sulfon.

1.5-bis-p-hydroxyphenylpentane.

1.6-bis-p-hydroxyphenoxyhexane, 4
-Tolyl hydroxybenzoate, 4-hydroxybenzoic acid α-phenylhensyl ester, phenylpropyl 4-hydroxybenzoate, phenethyl 4-hydroxybenzoate, p-chlorohensyl 4-hydroxybenzoate, 4
-Hydroxybenzoic acid-p-methoxyhen2cinyl, 4-
Hydroxybenzoic acid hensyl ester, 4-hydroxybenzoic acid-m-chlorohensyl ester, 4-hydroxybenzoic acid-β-phenethyl ester, 4-hydroxy-2',4'-dimethyldiphenylsulfone β
-Phenethyl orselinate, cinnamyl orselinate, orserinic acid-〇-chlorophenoxyethyl ester, 0-ethylphenoxyethyl orselinate, o-
Phenylphenoxyethyl orselinate + m-phenylphenoxyethyl orselinate, 2,4-dihydroxybenzoic acid-β-3°-1-butyl-4'-hydroxyphenoxyethyl ester, 1-t-butyl-4-p
-Hydroxyphenylsulfonyloxyhenzene, 4-
N-hensylsulfamoylphenol, 2,4-dihydroxybenzoic acid-β-phenoxyethyl ester, 2
, 4-dihydroxy-6-methylbenzoic acid hensyl ester, methyl bis-4-hydroxyphenylacetate, ditolylthiourea, 4.4'-diacetyldiphenylthiourea, 3-phenylsalicylic acid, 3-cyclohexylsalicylic acid, 3. 5-tart-butylsalicylic acid, 3-methyl-5-pencylsalicylic acid, 2-phenyl-5-(α,α-dimethylbenzyl)salicylic acid, 3
I 5-c(α-methylhensyl)salicylic acid, 5-
t-octylsalicylic acid, 3,5-t-butylsalicylic acid, 3-chloro-5-cumylsalicylic acid, 3-methyl-5-t-octylsalicylic acid, 3-methyl-5-α
-Methylbensylsalicylic acid, 3-methyl-5-cumylsalicylic acid, 3,5-di-t-7milsalicylic acid, 3-
Phenyl-5-hensylsalicylic acid.

3-Phenyl-5-t-octylsalicylic acid, 3-phenyl-5-α-methylhensylsalicylic acid, 3.5-t-octylsalicylic acid, 3,5-bis(α-methylhensyl)salicylic acid, 3,5-salicylic acid Mirsalicylic acid, 4
-Methyl-5-(α-methylhensyl)salicylic acid, 4
-Methyl-5-cumylsalicylic acid, 3-(α-methylhensyl)-6-methylsalicylic acid, 3-(α-methylhensyl)-6-phenylsalicylic acid, 3-triphenylmethylsalicylic acid, 3-diphenylmethylsalicylic acid,
4-n-dodecylsalicylic acid, 4-t-dodecylsalicylic acid + 4-n-dodecylsalicylic acid, 4-n-pentadecylsalicylic acid, 4-n-heptadecylsalicylic acid, 5-(1,3-diphenylbutyl)-salicylic acid ,5
-n-octadecylsalicylic acid, 4-pentadecylsalicylic acid, 3゜5-bis(α-methylhensyl)salicylic acid, 3゜5-bis-t-octylsalicylic acid, 5-octadecylsalicylic acid, 5-α-(p-α-methyl hensylphenyl)ethylsalicylic acid, 3-α-methylhensyl-5-t-octylsalicylic acid, 5-titradecylsalicylic acid, 4-hexyloxysalicylic acid, 4-cyclohexyloxysalicylic acid, 4-octyloxysalicylic acid, 4-decyl Oxysalicylic acid, 4-dodecyloxysalicylic acid, 4-tetradecyloxysalicylic acid, 4
-pentadecyloxysalicylic acid, 4-hexadecyloxysalicylic acid, 4-octadecyloxysalicylic acid,
4-icosyloxysalicylic acid, 4-driacontyloxysalicylic acid, 4-oleyloxysalicylic acid, 4-
β-Phenethyloxysalicylic acid, 4-β-dodecyloxyethoxysalicylic acid, 4-(12-chlorododecyl)oxysalicylic acid, 4-β-N-stear0ylaminoethoxysalicylic acid, 4-β-N-mylnutoylaminoethoxy Salicylic acid, 4-β-perfluorohexylethoxysalicylic acid, 4-dodecyloxy-5-chlorosalicylic acid, 4-dodecyloxy-5-methylsalicylic acid, 4-dodecyloxy-6-methylsalicylic acid, 4-dodecyloxy-e-phenyl Salicylic acid, 4-methoxy-6-dozosyloxysalicylic acid, 6-octazosyloxysalicylic acid + 4p'-octylphenyloxysalicylic acid, 4-p-dodecyloxyphenyloxysalicylic acid, 4-p-chlorophenoxy-6-butylsalicylic acid , 4-p-phenylphenoxysalicylic acid,
4-p-N-myristoylcarbamoylphenyloxysalicylic acid, 4-β-p-methoxyphenoxyethoxysalicylic acid, 4-hensyloxy-6-todecyloxysalicylic acid, 5-dodecylsulfonylsalicylic acid, 5-
Examples include dodecylsulfosalicylic acid and 3-methyl-5-dodecylsulfosalicylic acid.

The electron-accepting compound is an electron-donating colorless dye of 50 to 80
It is preferable to use 0% by weight, preferably 1% by weight.
00 to 500% by weight. With respect to 4-hydroxy-4'-isopropoxydiphenylsulfone, which is an electron-accepting compound according to the present invention, the above-mentioned electron-accepting compound is
It is preferable to mix in a proportion of 10 to 100% by weight. Further, two or more of the above electron-accepting compounds may be used in combination.

Examples of the sensitizer of the present invention include JP-A-58-57989
No., JP-A-58-87094, JP-A-63-3937
Examples include compounds disclosed in No. 5 and the like. Representative examples thereof include aromatic ethers (particularly hensyl ethers and di(substituted phenoxy) alkanes), esters and/or aliphatic amides, ureidos, and aromatic amides or ureidos.

Next, a typical method for producing a heat-sensitive coloring layer of the present invention will be described.

The electron-donating colorless dye, the electron-accepting compound, and the sensitizer are dispersed to a size of several microns or less using a hole mill, sand mill, etc., together with an aqueous solution of a water-soluble polymer such as polyvinyl alcohol. The sensitizer is added to either the electron-donating colorless dye or the electron-accepting compound, or both, and is dispersed simultaneously, or in some cases, a eutectic product is prepared in advance with the electron-donating colorless dye or the electron-accepting compound. , may be dispersed.

These dispersions are mixed after dispersion, and pigments and
Add surfactant, binder, metal soap, wax, antioxidant, ultraviolet absorber, etc. to make a heat-sensitive coating liquid.

The obtained heat-sensitive coating liquid is coated and dried on high-quality paper, high-quality paper with an undercoat layer, synthetic paper, plastic film, etc., and then smoothed by calendering to obtain the desired heat-sensitive recording material. In this case, it is particularly preferable to use a support having a smoothness defined by JIS-8119 of 500 seconds or more, particularly 800 seconds or more from the viewpoint of dot reproducibility. To obtain a support with a smoothness of 500 seconds or more, ■ Use a material with a highly smooth layer such as synthetic paper or plastic film ■ Provide an undercoat layer containing pigment as the main component on the support ■ Super Calender There are means such as increasing the height of the smooth layer of the support by using the same method.

The binder is preferably a compound that dissolves 5% by weight or more in water at 25°C, and specifically, polyvinyl alcohol (including modified polyvinyl alcohols such as carboxy-modified, itaconic acid-modified, maleic acid-modified, and silica-modified polyvinyl alcohols). , methylcellulose, carboxymethylcellulose, starches (including modified starches), gelatin, gum arabic, casein, styrene-maleic anhydride copolymer hydrolyzate, polyacrylamide, saponified vinyl acetate-polyacrylic acid copolymer, etc. can be given. These binders are used not only for dispersion but also for the purpose of improving coating film strength. A synthetic polymer latex binder such as acid methyl butadiene copolymer or polyvinylidene chloride may also be used.

Further, a crosslinking agent for a suitable binder may be added depending on the type of these binders, if necessary.

Pigments include calcium carbonate, barium sulfate, lithopone, waxite, kaolin, silica, and amorphous silica.

As the metal soap, higher fatty acid metal salts are used, such as zinc stearate, calcium stearate, aluminum stearate, and the like.

Further, an antistatic agent, an antifoaming agent, a conductive agent, a fluorescent dye, a coloring dye, etc. may be added as necessary.

The coated heat-sensitive recording material is dried and subjected to a process such as a calender before being used.

Further, a protective layer may be provided on the heat-sensitive coloring layer if necessary. As the protective layer, any one known as a protective layer for heat-sensitive recording materials can be used.

Furthermore, if necessary, a back coat layer may be provided on the opposite side of the support of the heat-sensitive recording material from the heat-sensitive coloring layer. As the hack coat layer, any material known as a back coat layer for heat-sensitive recording materials can be used.

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited only to the Examples below.

(Example-1) 2-anilino-3-methyl-6-N-ethyl-N-tetrahydrofurfuryl 7minofluorane as an electron-donating colorless dye, 4-hydroxy- as an electron-accepting compound
4'-isopropoxydiphenyl sulfone, β-naphthylhensyl ether as a sensitizer, 209 to 100 each
9 5% polyvinyl alcohol (Kuraray PVA-10
5") Dispersed with an aqueous solution in a ball mill for one day and night to make the average particle size 1.5 μm or less to obtain each dispersion. Also,
Calcium carbonate 809 to sodium hexametaphosphate 0.5
% solution 1609 using a homogenizer to obtain a pigment dispersion.

Each of the dispersions prepared as described above was mixed with 59 parts of an electron-donating colorless dye dispersion, 109 parts of an electron-accepting compound dispersion, 109 parts of a β-naphthylhensyl ether dispersion, and 59 parts of a calcium carbonate dispersion. A heat-sensitive coating liquid was obtained by adding 21% zinc stearate emulsion 39. This heat-sensitive coloring layer coating solution was applied onto a high-quality paper with a basis weight of 509/m2 using a wire bar so that the dry weight of the coating layer was 59/m2, and was dried at 50°C for 1 minute to obtain heat-sensitive recording paper. Ta.

(Example-2) Instead of using 2-anilino-3-methyl-6-N-ethyl-N-tetrahydrofurfurylaminofluorane in Example-1, 2-anilino-3-methyl-6-N −
A heat-sensitive recording paper was obtained in the same manner except that methyl-N-tetrahydrofurfuryl 7minofluorane was used to prepare a heat-sensitive coating solution.

(Example-3) Instead of using 2-anilino-3-methyl-6-N-ethyl-N-tetrahydrofurfuryl 7minofluorane in Example-1, 2-anilino-3-methyl-6-N-
A thermal recording paper was obtained in the same manner except that a thermal coating liquid was prepared using butyl-N-tetrahydrofurfuryl 7minofluorane.

(Comparative Example-1) Instead of using 2-anilino-3-methyl-6-N-ethyl-N-tetrahydrofurfurylamine fluoran in Example-1, 2-anilino-3-methyl-6-sibutyl A thermal recording paper was obtained in the same manner except that aminofluoran was used to prepare the thermal coating liquid.

(Comparative Example-2) Instead of using 2-anilino-3-methyl-6-N-ethyl-N-tetrahydrofurfurylaminofluorane in Example-1, 2-anilino-3-methyl-6-dinifluorane was used. A thermal recording paper was obtained in the same manner except that thylaminofluoran was used to prepare the thermal coating liquid.

(Comparative Example-3) A thermal recording paper was prepared in the same manner as in Example-1 except that bisphenol A was used instead of 4-hydroxy-4'-isopropoxydiphenyl sulfone to prepare a thermal coating liquid. I got it.

The surface of the thermal recording paper obtained as described above was treated with a calender, and the smoothness was 300±5 as Beck smoothness.
The temperature was adjusted to 0 seconds to obtain a heat-sensitive recording material.

The thermal recording paper was evaluated as follows.

■The heat resistance test was conducted using a sample printed at 30mJ/mm2 of printing energy using a Kyocera Uji tester at 60°C.
The initial J degree and the J degree after aging were measured using a Maches densitometer after 24 hours in a %R)I environment.

(2) In the chemical resistance test, filter paper was impregnated with castor oil and placed on the colored side of the recording paper obtained by the above method to evaluate the degree of fogging in the white background area and decolorization (discoloration) in the colored area.

■Light resistance test was conducted using a fluorescent lamp at 5000 LuX.
The coloring of the white background area after irradiation for 00 hours was measured using a Maches densitometer (Yet low Fi 1ter).

The above results are shown in the table below.

◎ Very excellent O Excellent (some changes are observed) △ Practical (images can be read) × Not possible (images are very difficult to read) As can be seen from the results in the table, the recording material of the present invention It can be seen that it has high sensitivity, does not cause fogging or decolorization of colored areas due to chemicals, and has extremely excellent performance with good heat resistance and light resistance.

Claims (2)

[Claims] (1) In a heat-sensitive recording material in which a heat-sensitive coloring layer containing an electron-donating colorless dye and an electron-accepting compound is provided on a support, the heat-sensitive coloring layer contains 4-hydroxy-4'-isopropoxydiphenyl sulfone. A heat-sensitive recording material characterized in that the electron-donating colorless dye contains a compound represented by the following general formula [I]. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [I] (R represents a lower alkyl group.) (2) The heat-sensitive recording material according to claim 1, wherein the electron-donating colorless dye is 2-anilino-3-methyl-6-N-ethyl-N-tetrahydrofurfurylaminofluorane.