JPS61242889A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material capable of forming a color with high density under low thermal energy of a thermal head and enhanced in sensitivity, byusing a specified ether compound as a color developer and using a specified heat-fusible substance therewith. CONSTITUTION:A thermal color forming layer comprising a normally colorless or light-colored leuco dye and a color developer capable of developing the color of the dye as main constituents is provided on a base to produce a thermal recording material. In the recording material, at least one of ether compounds of formulas (1) and (2) is used as the color developer, and at least one heat- fusible substance selected from octahydroanthracene, p-benzylbiphenyl, acenaphthene, m-terphenyl and phenyl 1-hydroxy-2-naphthoate is incorporated in the color forming layer. Tough the ether compounds are excellent for use as highly sensitized color developer because of the low melting point of 100-120 deg.C thereof, the sensitivity-enhancing effect is increased when at least one selected heat-fusible substance is jointly used.

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.

[Conventional technology]

Recently, various recording sheets have been researched and developed and put into practical use in the information recording field in response to social demands such as the diversification and increase of information, resource conservation, and pollution-free technology.Among them, thermal recording sheets are (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 heat-sensitive recording sheet is manufactured by coating and drying a heat-sensitive coloring layer liquid containing a coloring component that can cause a coloring reaction when heated, on a support such as ordinary paper, synthetic paper, or a 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
-4842 publication includes acetamide, stearamide,
Nitrogen-containing compounds such as l-nitroaniline and dinitrile phthalate, acetoacetanilide in JP-A-52-106746, and N-containing compounds in JP-A-53-11036.
, N-diphenylamine derivative, benzamide derivative,
The speed can be increased by incorporating carbazole derivatives, alkylated biphenyls and biphenylalkanes in JP-A No. 53-39139, and p-oxybenzoic acid ester derivatives in JP-A-56-144193. , methods for increasing sensitivity have been disclosed, but among these methods, the method using a P-oxybenzoic acid ester derivative as a color developer is the most 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〕

In view of the current situation, the present inventors have conducted intensive research on increasing the sensitivity of heat-sensitive recording materials, and as a result, have completed the present invention. Therefore, an object of the present invention is to develop color with high density even with low thermal energy of the thermal head. The object of the present invention is to provide a heat-sensitive recording material with high sensitivity (high dynamic color development sensitivity).

〔composition〕

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 is provided, characterized in that an ether compound represented by the following formula is used as the color developer, and this is used together with a specific heat-fusible substance.

The color developer used in the present invention is:

At least one of the ether compounds represented by Formula and Formula 1 is one. These ether compounds have a melting point of 100 to 12
It is excellent as a high-sensitivity color developer because its temperature is 0°C, which is lower than the conventionally used bisphenol A, but octahydroanthracene, P-benzylbiphenyl, acenaphthene, sono-terphenyl, and l-hydroxy-2-naphthoic acid When used together with at least one thermofusible substance selected from phenyl, the effect of increasing sensitivity is greater than when used together with higher fatty acid amide or the like. These thermofusible substances are aromatic compounds with a melting point of 70 to 100°C, so they have a high ability to melt and dissolve color developers and leuco dyes, and are superior to higher fatty acid amides that are commonly used in the past. It is also thought that the sensitivity can be increased.

The above-described color developer consisting of an ether compound is used in an amount of 1 to 10 times the amount of the leuco dye (based on weight), preferably 2 to 5 times the amount of the leuco dye, and the thermofusible substance is used in an amount of 0.0 times the amount of the leuco dye.
It is used in an amount of 5 to 10 times, preferably 1 to 5 times.

In addition, in the present invention, leuco dyes may be applied alone or as a mixture of two or more types, and as such leuco dyes, those applied to this type of heat-sensitive material may be arbitrarily applied. Examples of leuco dyes include the following. In addition to the above-mentioned ether compound color developer,
In order to prevent fading of recorded images and yellow dust on the background, an appropriate amount of a color developer as shown below may be added.

[Leuco dye]

3,3-bis(p-diethylaminophenyl)-phthalide, 3,3-his(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone).

3.3-His(p-dimethylaminophenyl)-6-
Diethylaminophenyl.

3.3-Bis(P-dimethylaminophenyl)-6-chlorphthalide.

3.3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3
-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6
-Methyl-7-chlorofluorane, 3-(N-p-tolyl-N-ethylamino)-6-methyl-7-7nylinofluorane, 3-pyrrolidino-6-methyl-7-7nylinofluorane, 2-(N -(3'-trifluoromethylphenyl)amino)-6-dinithylaminofluorane.

2-(3,6-bis(diethylamino)-9-(o-
Chloranilino)xantylbenzoic acid lactam).

3-diethylamino-6-methyl-7-(■-trichloromethylanilino)fluoran, 3-diethylamino-? -(o-chloroanilino)fluorane.

3-dibutylamino-7-(0-chloroanilino)fluoran, 3-N-methyl-N-7mylamino-6-methyl-7-
Anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-7nilinofluorane.

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-virirosvirane, 3-(2'-hydroxy-41-dimethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl)phthalide, 3-( 2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-nitrophenyl)
Phthalide.

3-(2'-Hydroxy-41-diethylaminophenyl)-3-(2'-methoxy-5'-methylphenyl)phthalide.

3-(2'-methoxy-4'-dimethylaminophenyl)-3-(2'-hydroxy-4'-chloro-5'
-methylphenyl)phthalide, 3-morpholino-7-(N-propyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane.

3-Diethylamino-5-chloro-7-(N-benzyl-trifluoromethylanilino)fluoran.

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-? -(o-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-(α-phenylethylamino)fluoran.

3-diethylamino-7-piperidinofluorane.

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

[Developer]

gallic acid, salicylic acid, 3-isopropylsalicylic acid,
3-cyclohexylsalicylic acid, 3,5-tar
t-Butylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, 4,4'-isopropylidene diphenol, 4,4'-isopropylidene bis(2-chlorophenol), 4,4'-isopropylidene bis (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(2-7art-butylphenollidene diphenol, 4,4'-cyclohexylidene bisphenol, 4,4'-cyclohexylidene bis(2)
-Methylphenol, 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, phloroglycin, phloroglycin Carboxylic acid, 4-tart-octylcatechol, 2,2'-methylenebis(4-chlorophenol),
2.2'-methylenebis(4-methyl-6-ter
t-butylphenol), 2,2'-dihydroxydiphenyl, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-hydroxybenzoate,
Benzyl p-hydroxybenzoate, P-chlorobenzyl p-hydroxybenzoate, P-hydroxybenzoic acid-
〇 -Chlorbenzyl, p-hydroxybenzoic acid-p-
Methylbenzyl, n-octyl p-hydroxybenzoate, benzoic acid, zinc salicylate, 1-hydroxy-2-
naphthoic acid, 2-hydroxy-6-naphthoic acid, zinc 2-hydroxy-6-naphthoic acid, 4-hydroxydiphenylsulfone, 4-hydroxy-4'-chlorodiphenylsulfone, bis(4-hydroxyphenyl)sulfide, 2- Hydroxy-ph-ruyl acid, 3,5-di-t
art-butylsalicylic acid zinc, 3,5-di-tart
-tin butylsalicylate, tartaric acid, oxalic acid, maleic acid, citric acid, succinic acid, stearic acid, 4-hydroxyphthalic acid.

Boric acid 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, styrene/butadiene copolymer, polyacrylic acid, polyacrylic ester, vinyl chloride/vinyl acetate copolymer, and Latexes of butyl methacrylate, ethylene/vinyl acetate copolymer, and styrene/butadiene/acrylic copolymer 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 and silica. , urea-formalin resin, styrene/methacrylic acid copolymer, polystyrene resin, etc. Examples of thermofusible substances include higher fatty acids or their esters, amides (methylolated products thereof), etc. ) or metal salts, petroleum waxes such as polyethylene, paraffin, microcrystalline wax, etc. 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, leuco dyes, color developers, binders, and other additives may be used alone or in a mixture other than the leuco dyes, protective colloids such as polyvinyl alcohol, surfactants, etc. may be added, and then ball milling, attritor,
After dispersing with a dispersing machine such as a sand mill, a heat-sensitive coloring layer coating solution is prepared according to the recipe, and applied onto 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] Since the heat-sensitive recording material of the present invention uses a combination of a color developer made of a specific ether compound and a specific heat-fusible substance, It uses less energy and has higher sensitivity than ever before.

〔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-methyl-N-cyclohexyl)amino-7-
7 Nilinofluorane 300 parts lO%
Polyvinyl alcohol aqueous solution 300# water
400〃[
B liquid] HOCaHs-5CHzCHzOCHzCHzS-Ca
Hs-OH 100 parts P-benzylbiphenyl 100 Calcium carbonate 100# Polycarboxylic acid type surfactant 5H2O% polyvinyl alcohol aqueous solution 300# Water
395 parts The mixture consisting of the above composition was pulverized and dispersed to prepare liquids A and B.6 Next, liquids A and B were prepared in a weight ratio of A:B=1:
Prepare a heat-sensitive coating liquid by mixing and stirring so that it becomes 52
It was coated on high-quality paper of g/rrr with a wire bar so that the coating amount after drying was 5 g/rrr. This coated paper was calendered to give a Beck smoothness of 700 to 1200 seconds to prepare a heat-sensitive recording material of the present invention.

Examples 2 to 8 HO-Csos -5CH2CH20CH2CH25- in the above [Liquid B]
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1, except that Caos -OH and l or p-benzylbiphenyl were changed as shown in Table 1.

Comparative Examples 1 to 3 Example 1 except that the developer and sensitizer shown in Table 1 were used.
A heat-sensitive recording material for comparison was prepared in the same manner as described above.

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 Kenko Electronics Co., Ltd. with a thin film head, the head power was 0.45 V/dot and the recording time for one line was 20 seconds.
/Ω, scanning line density 8 x 3.85 dots/am, pulse width 0.8.1.0.1.2.1.4, 1.6 m5e
c, and measure the print density using Macbeth Densitometer RD-51.
4 (filter vratten-106).

As can be seen from Table 1, it is clear that the thermal recording material of the present invention has a higher dynamic color development sensitivity than the known system using bisphenol A, benzyl P-hydroxybenzoate, and stearamide. .

Claims (1)

[Claims] (1) A heat-sensitive recording material in which a heat-sensitive coloring layer is provided on a support, and 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. As, the formula HO-C_6H_5-SCH_2CH_2OCH_2C
H_2S-C_6H_5-OH and formula HO-C_6H_5-SCH_2CH_2OCH_2C
At least one of the ether compounds represented by H_2OCH_2CH_2S-C_6H_5-OH is used, and in the heat-sensitive coloring layer, octahydroanthracene, p-benzylbiphenyl, acenaphthene, m-terphenyl, and 1-hydroxy-2-naphthoic acid are used. A heat-sensitive recording material characterized by containing at least one thermofusible substance selected from phenyl.