JPS62176882A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material having high sensitivity, by having not only at least one kind of a specific leuco dye with m.p. of specific temp. or less but also at least one kind of a specific compound contained and further mixing a specific developer. CONSTITUTION:At least one kind of a leuco dye with m.p. of 170 deg.C or less represented by general formula I (wherein R1 is a 2 or more C alkyl group, R2 is a 5 or more C alkyl group, an alkoxyalkyl group or a tetrahydrofuryl group, R3 is hydrogen or a methyl group and R4 is hydrogen, halogen or a alkylhalide group) and at least one kind of a compound represented by general formula II (wherein R is a 1-2C alkylene group, X and Y are a lower alkyl group, an aryl group, an aralkyl group or a halogen atom and may be the same or different and n and m are respectively independently an integer of 0-3) are contained in a thermal color forming layer. Further, either one of methyl 4-hydroxyphthalate, benzyl p-hydroxybenzoate or 1, 7-di(4- hydroxyphenylthio)-3, 5-dioxaheptane is mixed as a developer to prepare a thermal recording material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and a color developer.

[Prior art]

Recently, various recording sheets have been researched and developed in the field of information recording and put into practical use in response to social demands such as diversification and increase in information, resource conservation, and decentralization. Among them, thermal recording sheets (1) A colored image is recorded simply by heating, eliminating the need for a complicated development process; (2) It can be manufactured using a relatively simple and compact device;
Furthermore, the resulting recording sheet is easy to handle and maintenance costs are low; (3) paper is often used as a support; in this case, not only is the support cost low; Because of its advantages such as the feel of the recording sheet is similar to that of plain paper, it is used in the field of computer output, printers such as calculators, recorders for medical measurement, low and high speed facsimiles, automatic ticket vending machines, thermal copying, etc. Widely used.

The above-mentioned heat-sensitive recording sheet is manufactured by applying and drying a heat-sensitive coloring layer solution containing a coloring component capable of causing a coloring reaction when heated on a support such as ordinary paper, synthetic paper, or synthetic resin film. A colored image is recorded on the heat-sensitive recording sheet thus obtained by heating it with a thermal pen or a thermal head. Conventional examples of such heat-sensitive recording sheets include, for example, the heat-sensitive recording sheet disclosed in Japanese Patent Publication No. 43-4160 or Japanese Patent Publication No. 45-14039; Responsiveness was low, and sufficient color density could not be obtained during high-speed recording.

As a method for improving such drawbacks, for example, Japanese Patent Application Laid-Open No. 49-3
No. 4842 discloses nitrogen-containing compounds such as acetamide, stearamide, san-nitroaniline, and di-1-lyl phthalate; JP-A-52-106746 discloses acetoacetic anilide; JP-A-53-11036 discloses N
, N-diphenylamine derivative, benzamide derivative,
Carbazole derivatives, alkylated biphenyls and biphenyl alkanes in JP-A-53-39139, and P-oxybenzoic acid ester derivatives in JP-A-56-144193.

JP-A-59-68295 discloses that 1,7-bis(4
-Hydroxyphenylthio)-3,5-dioxaheptane has been disclosed to improve speed and sensitivity, but among these methods, benzyl P-hydroxybenzoate and 1,7- A method using bis(4-hydroxyphenylthio)-3,5-dioxane as a color developer was considered to be effective.

However, recently, the speed of thermal facsimile has become even faster.
As miniaturization is being considered, there is a growing demand for higher sensitivity of heat-sensitive recording sheets, and the above-mentioned methods for increasing sensitivity do not provide sufficiently satisfactory results.

〔the purpose〕

An object of the present invention is to provide a highly sensitive heat-sensitive recording material.

[Oval]

According to the present invention, in a heat-sensitive recording material in which a heat-sensitive coloring layer is provided on a support, the heat-sensitive coloring layer is composed mainly of a normally colorless or slightly light-colored leuco dye and a color developer capable of coloring the leuco dye when heated. A heat-sensitive recording material characterized by using at least one leuco dye represented by the following general formula (1) and having a melting point of 170°C or less, and containing at least one compound represented by the following general formula (II). provided.

(In the formula, R is an alkyl group having 2 or more carbon atoms, R2 is an alkyl group having 5 or more carbon atoms, an alkoxyalkyl group, or a tetrahydrofuryl group 1. R3 is hydrogen or a methyl group, R4 is hydrogen, halogen, or halogenated alkyl group) Indicates the group.

General formula (II) (wherein, R is an alkylene group having 1 to 2 carbon atoms, X and Y are lower alkyl groups, aryl groups, aralkyl groups, or halogen atoms, and X and V may be the same or different. Good(,n,
Each m independently represents an integer from θ to 3. ) Furthermore, the above color developer is methyl 4-hydroxyphthalate, p-
It is provided in a thermosensitive recording material which is benzyl hydroxybenzoate or l,7-di(4-hydroxyphenylthio)-3,5-dioxaheptane.

As a result of intensive research on increasing the sensitivity of heat-sensitive functional materials, the present inventors have found that the heat-sensitive coloring layer contains at least one fluoran compound represented by the general formula (1), and a compound represented by the general formula (II). By containing at least one of
It has been discovered that sensitivity can be increased by using either methyl hydroxyphthalate, benzyl P-hydroxybenzoate, or 1,7-di(4-hydroxyphenylthio)-3,5-dioxaheptane, and the present invention I have come to complete this.

Examples of the fluoran compound represented by the general formula (1) used in the present invention include 3-(N-ethyl-N-ethoxypropyl)amino-6
-Methyl-7-anilinofluorane, 3-(N-ethyl-N-tetrahydrofurfuryl)amino-6-methyl-
7-anilinofluorane, 3-(N-ethyl-N-di-
7 mil) amino-6-methyl-7-anilinofluorane, 3-(N-i-pentyl-N-m-hexyl)amino-
6-Methyl-7-anilinofluorane.

3-(N-octyl-N-i-propyl)amino-6-
Methyl-7-anilinofluorane, 3-(N-ethyl-N-ethoxypropyl)amino-6
-Chloro-7-7nylinofluorane etc., but
It is not limited to these.

Further, as examples of compounds represented by general formula (n), etc.

These compounds also contain methyl 4-hydroxyphthalate, benzyl P-hydroxybenzoate, or
1,7-di(4-hydroxyphenylthio)-3,5-
Even more favorable results are obtained when dioxaheptane is used.

Further, in the present invention, in addition to the leuco dye of general formula (1) and the compound represented by general formula (n), appropriate amounts of leuco dyes other than those described above and color developers may be added. Specific examples thereof include the following.

[Leuco dye]

3.3-bis(p-dimethylaminophenyl)-phthalide, 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone), 3.3-bis(p- dimethylaminophenyl)-6-dibutylaminophenyl, 3.3-bis(P-dimethylaminophenyl)-6-chlorophthalide, 3.3-bis(P-dibutylaminophenyl)phthaliz
- 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3
-diethylamino-7-chlorofluorane, 53-diethylamino-7-methylfluorane.

3-diethylamino-7,8-benzfluorane, 3-
Diethylamino-6-methyl-7-chlorofluorane, 3-(N-p-tolyl-N-dithylamino)-6-methyl-7-anilinofluorane.

3-pyrrolidino-6-methyl-7-anilinofluorane.

2-(N-(3'-trifluoromethylphenyl)amino)-6-dinithylaminofluorane.

2-(3,6-bis(diethylamino)-9-(o-chloroanilino)xantylbenzoic acid lactam), 3-diethylamino-6-methyl-7-(m-trichloromethylanilino)fluoran, 3-diethylamino-7 -(0-chlorodianilino)fluoran, 3-dibutylamino-7-(o-chloroanilino)fluoran, 3-N-methyl-N-amylamino-6-methyl-7-
Anilinofluorane.

3-N-Methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane.

3-diethylamino-6-methyl-7-anilinofluorane, 3-(N,N-diethylamino)-5-methyl-7-(
N.

N-dibenzylamino)fluoran, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrylospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrylospirane, 3-(2'- 3-(2'-hydroxy-41-dimethylaminophenyl)-3-(2'-methoxy- 5'-nitrophenyl) phthalide, 3-(2'-hydroxy-41-diethylaminophenyl)-3-(2'-methoxy-5'-methylphenyl) phthalide.

3-(2'-Me1-xy4'-dimethylaminophenyl)-3-(2'-hydroxy-4'-chloro-5
'-methylphenyl)phthalide.

3-morpholino-7-(N-propyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-1-lifluoromethylanilinofluorane.

3-diethylamino-5-chloro-7-(N-benzyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluorane.

3-Diethylamino-5-chloro-7-(α-phenylethylamino)fluoran, 3-(N-ethyl-P-toluidino)-7-(α-phenylethylamino)fluoran.

3-diethylamino-7-(o-methoxycarbonylphenylamino)fluoran.

3-diethylamino-5-methyl-7-(α-phenylethylamino)fluorane, 3-diethylamino-7-piperidinofluorane.

2-chloro-3-(N-methyltoluidino)-7-(p
-n-butylanilino)fluoran, 3-(N-benzyl-N-cyclohexylamino)-5
, 6-penzo 7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino 4
',5'-benzofluorane etc.

Further, as the color developer used in the present invention, various electron-accepting substances that react with the leuco dye and develop color when heated are used, and specific examples thereof include phenol as shown below. sexual substance.

Examples include organic or inorganic acidic substances, esters and salts thereof, and the like.

gallic acid, salicylic acid, 3-isopropylsalicylic acid,
3-cyclohexylsalicylic acid, 3,5-di t,c
rt, -butylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, 4,4'-isopropylidene diphenol, 4,4'-isopropylidene bis(2-chlorophenol), 4,4'-isopropylidene Screw (2,
6-dibromophenol), 4,4'-isopropylidene bis(2,6-dichlorophenol), 4,4'-isopropylidene bis(2-methylphenol), 4.4
'-isopropylidene bis(2,6-dimethylphenol), 4,4'-isopropylidene bis(2-tart
-butylphenol), 4,4'-5ec-butylidene diphenol, 4,4'-cyclohexylidenebisphenol, 4,4'-cyclohexylidenebis(2-
methylphenol), 4-t,crt-butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, 3,5-xylenol, thymol, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone , novolac type phenolic resin, 2,2'-thiobis(4,6-dichlorophenol), catechol, resorcinol, hydroquinone, pyrogallol, phloroglycine, phloroglycine carboxylic acid, 4-tart, -octylcatechol, 2
, 2'-methylenebis(4-chlorophenol), 2,
2'-methylenebis(4-methyl-6-t, art-butylphenol), 2,2'-dihydroxydiphenyl, ethyl P-hydroxybenzoate, propyl P-hydroxybenzoate, butyl P-hydroxybenzoate, P-hydroxy Benzyl benzoate, P-hydroxybenzoic acid-
p-Chlorbenzyl, P-hydroxybenzoate-〇-chlorobenzyl, P-hydroxybenzoate-P-methylbenzyl, p-hydroxybenzoate-〇-octyl, benzoic acid, zinc salicylate, l-hydroxy-2-naphthoate acid, 2-hydroxy-6-naphthoic acid, zinc 2-hydroxy-6-naphthoate, 4-hydroxydiphenylsulfone, 4-hydroxy-4'-chlorodiphenylsulfone, bis(4-hydroxyphenyl)sulfide, 2-
Hydroxy-p-toluic acid, 3,5-di-t, crt
, -zinc butylsalicylate, tin 3,5-di-tart-butylsalicylate.

tartaric acid, oxalic acid, maleic acid, citric acid, succinic acid,
Stearic acid, 4-hydroxyphthalic acid, 4-hydroxybenzoic acid chlorobenzyl ester, etc.

In the present invention, in order to bind and support the leuco dye and color developer on the support, various commonly used binders can be used as appropriate, such as polyvinyl alcohol, starch and its derivatives, methoxycellulose, hydroxyl, etc. Cellulose derivatives such as ethyl cellulose, carboxymethyl cellulose, methyl cellulose, and ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic amide/acrylic ester copolymer, acryl amide/acrylic ester/methacrylic acid ternary copolymer, styrene/ Maleic anhydride copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali salt,
In addition to water-soluble polymers such as polyacrylamide, sodium alginate, gelatin, and casein, polyvinyl acetate, polyurethane, polyvinyl chloride, polyvinylidene chloride, styrene/butadiene copolymer, polyacrylic acid, polyacrylic ester, and vinyl chloride. /vinyl acetate copolymer, styrene/acrylic acid ester copolymer, polybutyl methacrylate, ethylene/vinyl acetate copolymer, styrene/
Latexes such as butadiene/acrylic copolymers can be used.

In addition, in the present invention, in addition to the leuco dye and color developer, if necessary, auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers, surfactants, thermofusible substances ( or lubricant), etc. can be used in combination. In this case, fillers include, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and surface-treated inorganic fine powders such as calcium carbonate and silica. Others, urea-
Organic fine powders such as formalin resin, styrene/methacrylic acid copolymer, and polystyrene resin can be mentioned, and examples of thermofusible substances include higher fatty acids or their esters and amides (including their methylolated products). In addition to metal salts, various waxes, dimethyl terephthalate, condensates of aromatic carboxylic acids and amines, phenyl benzoate, higher linear glycols, dialkyl 3,4-epoxy-hexahydrophthalate, higher ketones. ,
Examples include other thermofusible organic compounds having a melting point of about 70 to 120°C. Furthermore, if necessary, an undercoat layer made of a filler or a water-soluble binder can be provided between the support and the thermosensitive coloring layer.

Generally known methods can be used to obtain the heat-sensitive recording material of the present invention. That is, a leuco dye, a color developer, a binder, and other additives may be used alone or in a mixture other than the leuco dye, and a protective colloid substance such as polyvinyl alcohol, a surfactant, etc. may be added to the ball mill, attritor, etc.
After dispersing with a dispersing machine such as a sand mill, a heat-sensitive coloring layer coating solution is prepared according to the recipe, coated on a support such as paper, synthetic paper, film, etc., dried, and then calendered to produce the heat-sensitive recording of the present invention. Materials are obtained.

〔effect〕

The heat-sensitive recording material of the present invention contains a leuco dye represented by general formula (1) with a melting point of 170° C. or less for at least 1 second, and at least one compound represented by general formula (II). A highly sensitive heat-sensitive recording material can be obtained. In addition, especially when methyl 4-hydroxyphthalate, benzyl P-hydroxybenzoate, or 1,7-di(4-hydroxyphenylthio)-3,5-dioxaheptane is used as a color developer, , more favorable results are obtained.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples. Note that all parts and percentages shown below are based on weight.

Example 1 [Liquid A] 3-(N-ethyl-N-ethoxypropyl)amino-6
-Methyl-7-anirite fluorane 300 parts 10% polyvinyl alcohol water tM solution 300# water
400# [B
Liquid] Benzyl p-hydroxybenzoate 100 parts2.
2-bis(3,3',5,5'-tetrabromo-4
-Hydroxyphenyl)propane 50 parts Calcium carbonate 150 Zinc stearate 25 lO% polyvinyl alcohol aqueous solution 300 // Water
31511 Mixtures consisting of the above compositions were each mixed with a sand grinder,
After dispersing for 2 to 4 hours, liquids A and B were prepared.

Next, liquid A and liquid B were mixed and stirred so that the weight ratio was A:B=l:6 to prepare a heat-sensitive coating liquid.

[Liquid C]

Polystyrene 40% dispersion 750 parts lO
% polyvinyl alcohol aqueous solution 20011 water
50
II The above mixture was dispersed for 30 minutes using a sand grinder to obtain an undercoat coating liquid.

Next, apply this undercoat coating liquid at 52 g/n? After coating and drying on high-quality paper so that the coating amount after drying was 4 g/rrr to form an undercoat layer, the heat-sensitive coating liquid was applied so that the leuco dye coating amount after drying was 0.5 g/rrr. It was coated and dried. These coated papers were calendered to a Beck smoothness of 700 to 1,500 scc to prepare a heat-sensitive recording material of the present invention.

Example 2 A heat-sensitive recording material was also prepared in the same manner as in Example 1, except that the leuco dye in the liquid (A) was changed to the leuco dye shown in Table 1.

Comparative Example 1 A comparative heat-sensitive recording material was prepared in the same manner as in Example 1 except for the exceptions.

Comparative Example 2 3-(N-methyl-N-cyclohexyl)amino-6-methyl- instead of 3-(N-ethyl-■-ethoxypropyl)amino-6-methyl-7-anilitsufluorane in Comparative Example 1 A heat-sensitive functional material was produced in the same manner except that 7-anirite fluorane was used.

The above thermosensitive recording sheet was tested for dynamic color development sensitivity, and the results are shown in Table 1.

The test method in this case is as follows. Using a printing experiment device manufactured by Matsushita Electronic Components Co., Ltd. with a thin film head, head power was 0.45 V/dot, and 1 line recording time was 20 m5.
IQ, scanning line density 8 x 3.85 dots/IIm conditions.

Set the pulse width to 0.6.0.8.1.0.1.2.1.4
(msec), and the print density was measured using a Macbeth densitometer RD-514 (filter Vrattcn-106).

Table 1 shows that the heat-sensitive recording material of the present invention has higher sensitivity than conventional materials.

Claims (2)

[Claims] (1) In a heat-sensitive recording material in which a heat-sensitive color forming layer is provided on a support, the heat-sensitive coloring layer is composed mainly of a usually colorless or slightly light-colored leuco dye and a color developer capable of coloring the leuco dye when heated, in which the leuco dye is There are the following general formulas (I), ▲mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R_1 is an alkyl group with 2 or more carbon atoms, R_2 is an alkyl group with 5 or more carbon atoms, an alkoxyalkyl group, or a tetrahydro Furyl group, R_3 is hydrogen or methyl group,
(R_4 represents hydrogen, halogen, or halogenated alkyl group) At least one fluoran compound with a melting point of 170°C or less is used, and the following general formula (II) ▲Mathematical formula, chemical formula, table, etc.▼(II ) (wherein, R is an alkylene group having 1 to 12 carbon atoms, X and Y
represents a lower alkyl group, an aryl group, an aralkyl group, or a halogen atom, X and Y may be the same or different, and n and m each independently represent an integer of 0 to 3. ) A heat-sensitive recording material characterized by containing at least one compound represented by: (2) Claim 1, wherein the color developer is methyl 4-hydroxyphthalate, benzyl p-hydroxybenzoate, or 1,7-di(4-hydroxyphenylthio)-3,5-dioxaheptane. Heat-sensitive recording material described in Section 1.