JPH0428591A - Sensitizer and heat sensitive recording material - Google Patents

Abstract

PURPOSE:To improve light resistance, moisture resistance and plasticizer resistance by forming from compound of predetermined composition. CONSTITUTION:A sensitizer made of compound represented by a formula is formed. In the formula, R1, R2 are aliphatic hydrocarbon group containing 4 or less carbons; x is hydrocarbon group containing 10 or less carbons. The hydrocarbon group containing 4 or less carbon of the R1, R2 includes, for example, normal chain or branched alkyl group such as methyl, ethyl, n-propyl; normal chain or branched alkenyl group such as vinyl, aryl, propenyl and alkyl group. Desirably, methyl, ethyl, tert-butyl. The hydrocarbon group containing 10 or less carbons of the x includes, for example, normal chain or branched alkyl group such as methyl, ethyl, n-propyl; normal chain or branched alkenyl group and alkynyl group such as vinyl, aryl; carbon cyclic group such as phenyl, cyclopentyl, cyclohexyl group; alkyl group containing carbon cyclic group such as tryl group; alkoxy group containing carbon cyclic group such as methoxyphenyl group, etc.

Description

[Detailed description of the invention] [Industrial application fields] The present invention relates to a sensitizer and a heat-sensitive recording material.

More specifically, the present invention relates to a heat-sensitive recording material that has extremely high color development sensitivity and excellent whiteness, light resistance, moisture resistance, and plasticizer resistance.

[Prior Art] Heat-sensitive recording materials are produced by melting an electron-donating colorless coloring agent (hereinafter also referred to as coloring agent) and an electron-accepting color developing substance (hereinafter also referred to as coloring agent) with heat to cause them to associate. It is made using the principle of color development.

Thermosensitive recording materials have recently been used for various recording purposes such as facsimiles and POS labels.

As the coloring agent, a lactone compound such as crystal violet lactone is used, and as the color developer, a solid acidic substance, a phenol compound, a percussion acid, or a metal compound thereof is used.

Furthermore, in recent years there has been a significant demand for faster information, and various high-speed devices have been developed. Along with this, highly sensitive heat-sensitive recording materials have also been developed. For example, in order to improve the sensitivity by using color forming agents and color developing agents in combination, the use of sensitizers such as benzyl biphenyls (Japanese Unexamined Patent Publication No. 11-11-082382)
Publication), combined use of l,2-bis(phenoxy)ethane (
Tokukai Sho Go-+! 588) and triphenylmethane (Japanese Patent Publication No. 1-53640).

[Problems to be Solved by the Invention] However, heat-sensitive recording materials using conventional sensitizers have insufficient light resistance, moisture resistance, and plasticizer resistance.

[Means for Solving the Problems] The present inventors have made intensive studies to obtain a heat-sensitive recording material that has high sensitivity, high whiteness, light resistance, moisture resistance, and plasticizer resistance, and as a result, the present invention has been developed. reached. That is, the present invention is represented by the general formula % (1) [wherein R+ and R2 are aliphatic hydrocarbon groups having 4 or less carbon atoms; X is a hydrocarbon group having 10 or less carbon atoms] Claim I: A sensitizer characterized by comprising the compound (A); and a heat-sensitive recording material in which an electron-donating colorless color former and an electron-accepting color developer are placed on a support and heated to melt to develop color. This is a heat-sensitive recording material characterized by containing the sensitizer described above.

In the general formula (1), the aliphatic hydrocarbon groups having 4 or less carbon atoms in R8 and R2 include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutylN5ec
Straight chain or branched alkyl groups such as -butyl, jerj-butyl; straight chain or branched alkenyl groups and alkynyl groups such as vinyl, allyl, propenyl, impropenyl, 2-butenyl, ethynyl, 2-propynyl, etc. can.

Preferred are methyl, ethyl and tert-butyl.

The bonding position of RIO1R20 to the benzene nucleus is -Os
-rrh-p position may be used, but -p position is usually preferred.

In general formula (1), the hydrocarbon group having carbon number IO or less in x is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, 5ec-butyl, ter
Straight chain or branched alkyl groups such as t-butyl, pentyl, hexyl; Straight chain or branched alkenyl groups and alkynyl groups such as vinyl, allyl, propenyl, impropenyl, 2-butenyl, ethynyl, 2-propynyl; phenyl, Examples include carbocyclic groups such as cyclopentyl and cyclohexyl groups; alkyl group-containing carbocyclic groups such as tolyl group; and alkoxy group-containing carbocyclic groups such as methoxyphenyl group.

Preferred are tert-butyl, phenyl, cyclopentyl and cyclohexyl groups.

The specific examples of the compound (A) represented by the general formula (1) are as follows.

(1) Diarylmethane derivative from alkoxybenzene or alkenoxybenzene and an aliphatic aldehyde (2) Diarylmethane derivative from alkoxybenzene or alkenoxybenzene and an aromatic aldehyde, alkoxybenzene or alkenoxybenzene and carbocycle Preferred compounds (A) are diarylmethane derivatives from an alkoxybenzene and an aliphatic aldehyde, diarylmethane derivatives from an alkoxybenzene and an aromatic aldehyde, and diarylmethane derivatives from an alkoxybenzene and a carbocyclic aldehyde. Among the diarylmethane derivatives, particularly preferred are diarylmethane derivatives from anisole and an aliphatic aldehyde, diarylmethane derivatives from anisole and an aromatic aldehyde, and diarylmethane derivatives from anisole and a carbocyclic aldehyde.

Two or more different types of compounds (A) may be used in combination. In addition, the compound (A) described in Japanese Patent Application No. 1-28329 filed by the present applicant, Japanese Patent Application No. 1-28329; Compound (A) described in specification No.-41133, Japanese Patent Application No. 1-134080
Compound (A) described in the specification of the patent application No. -15130
Compound (A) described in Mei IB No. 4, Patent Application No. 1-158
Compound (A) described in specification No. 729, patent application No. 1-25
Compound (A) described in specification No. 6220, patent application No. 1-2
Compound (A) described in specification No. 56221, patent application No. 1-
Compound (A) described in specification No. 263551, Patent Application No. 1999
Compound (A) described in Japanese Patent Application No. 1-288747, Compound (A) described in Japanese Patent Application No. 1297142, Compound (A) described in Japanese Patent Application No. 1-323199, Japanese Patent Application No. 2-323199 Compound (A) described in specification No. 5541, compound (A) described in Japanese Patent Application No. 2-42844, 1990
Compound (A) described in patent application (2) (title of invention: sensitizer and heat-sensitive recording material) filed on April 20, 1990 and patent application (2) (invention) filed on April 24, 1990 Name: Compound (A) described in sensitizer and heat-sensitive recording material)
One type or two or more types of these may be used in combination.

The compound (A) represented by the general formula (1), a so-called sensitizer, can be produced by any method, such as P, P'
-Dimethoxytriphenylmethane can usually be obtained from anisole and benzaldehyde by Baeyer reaction.

More specifically, for example, the presence of a condensing agent such as aluminum chloride, iron trichloride, tin tetrachloride, zinc chloride, boron fluoride, P-)luenesulfonic acid, sulfuric acid, phosphorus pentoxide, phosphoric acid, hydrofluoric acid, etc. Below, anisole, benzaldehyde and benzene (solvent) are dissolved and heated to reflux. Then, the solvent is distilled off and distilled under reduced pressure to obtain a product.

Recrystallized from methanol/chloroform mixture to 102~
P,P'-dimethoxytriphenylmethane at 103°C can be obtained.

As the color forming agent constituting the recording layer in the heat-sensitive recording material of the present invention, those used in conventional heat-sensitive or pressure-sensitive recording materials can be used. For example, color formers such as triarylmethane, diphenylmethane, xanthine, phenothiazine, and spiropyran are preferably used.

As a triarylmethane coloring agent, 3,3-bis(
p-dimethylaminophenyl)-6-dimethylaminophthalide (crystal violet lactone, abbreviated as CvL), 3,3-bis(p-dimethylaminophenyl)phthalide) 3-(p-dimethylaminophenyl)
-3-(1,2-dimethylindole-dimethylaminophenyl)-3-(2-methylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(2-phenylindole-3- )
Phthalide, 3,3-bis(l,2-dimethylindol-3-yl)-5-dimethylaminophthalide, 3,3-
Bis-(I,2-dimethylindol-3-yl)-6
-dimethylaminophthalide, 3,3-bis(9-ethylcarbazol-3-yl)-5-dimethylaminophthalide, 3,3-bis(2-phenylindol-3-yl)-5-dimethylaminophthalide 3-p-dimethylaminophenyl-3-(+-methylpyrrol-2-yl)
-G-dimethylaminophthalide and the like.

Examples of diphenylmethane color formers include 4,4'-bisdimethylaminobenzhydrin benzyl ether, N-halophenylleuforamine, and N-2,4,5-trichlorophenylleuforamine.

As the xanthine coloring agent, rhodamine B-anilinolactam, rhodamine B (p-nitroanilino)lactam, rhodamine B (p-chloroanilino)lactam, 3
-dimethylamino-6-medoxyfluorane, 3-diethylamine-7-medoxyfluorane, 3-diethylamino-7-chloro-6-methylfluoraneethylamino-7-(acetylmethylamino)fluorane, 3-diethylamino -7-(dibenzylamino)fluorane, 3
Examples include -diethylamino-7-(methylbenzylamino)fluoran, 3-diethylamino-7-(chloroethylmethylamino)fluoran, and 3-diethylamino-7-(diethylamino)fluoran.

Examples of the phenothiazine color former include benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue, and the like.

As a spiropyran coloring agent, 3-methyl-spiro-
dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3,3'-cyclolosevirodinaphthopyran, 3-
Examples include benzyl-spiro-dinaphthopyran, 3-methyl-naphtho-(3-methoxy-benzo)-spiropyran, and 3-propyl-subilodibenzodipyran.

These color formers may be used alone or in combination of two or more.

On the other hand, as the color developer, various electron-accepting substances that react with the color former when heated to develop color can be used. As such an electron-accepting substance, a phenolic substance, an organic or inorganic acidic substance, or a salt thereof can be used. Examples of known color developers include "Color Developers for Thermal Recording Paper (1) to (Complete)" in "Paper and Pulp Technology Times", "Tic Time Co., Ltd., Vol. 30, No. B to Vol. 31, No. 3".
, written by Takashi Shiga" and "Color developer for thermal recording paper (+) - (complete), written by Takashi Shiga" in "Volume 32, No. 4 to Vol. 32, No. 10", both of which can be used. Specifically, the following are mentioned 2 (1) Bisphenol color developer (1-1) Non-sulfur containing bisphenol color developer 2-(4
-hydroxyphenyl)propane, 2-(3'hydroxyphenyl)propane, tetrabromobisphenol A
, 4.4'-isopropylidenediphenol, 4.
Bisphenol A derivative compounds such as 4'-butylidenebis (2-t-butyl-5-methylphenol); 4
, 4'-methylenebis(2-cyclohexyl-5-methylphenol), 4,4'-isopropylidenebis(2
-cyclohexyl-5-methylphenol), 4.
4'-Butylidene bis(2-cyclohexyl-5-methylphenol), 4,4'-cyclohexylidene bis(
2-cyclohexyl-5-methylphenol), 3.3
-ethyl bis(3-cyclohexyl-4-hydroxy-5-methylphenol)butanoate, 4-[1.1-bis(4-hydroxyphenyl)ethyl]biphenyl, 2-
[1.1-bis(4-hydroxyphenyl)ethyl]naphthalene, l-phenyl-1.1-bis(4-hydroxyphenyl)butane, 1.1-bis(p-hydroxyphenyl)cyclohexane, 4. Bisphenol A-based compounds such as 4'-butylidene bis(2-cyclohexyl-5-methylphenol) and methyl-phenyl-methylidene bisphenol: '+'-bis(4-
hydroxyphenyl)acetic acid, 2,2-bis(4-hydroxyphenyl)propionic acid, bis(4-hydroxyphenyl)acetic acid methyl ester, bis(4-hydroxyphenyl)acetic acid-n-methyl, bis(4-hydroxyphenyl) Propargyl acetate, bis(4-hydroxyphenyl)cinnamyl acetate, bis(4-hydroxyphenyl)benzyl acetate, bis(4-hydroxyphenyl)phenyl acetate, bis(4-hydroxyphenyl)phenethyl acetate, bis(4-hydroxyphenyl) Acetic acid-β-(4'-
ethoxyphenoxy)ethyl, 2,2-bis(4-hydroxyphenyl)acetate-3-phenoxypropyl, 2.
2-bis(4-hydroxyphenyl)valerin M-β-(4
'-Methylphenoxy)ethyl, bis(4-hydroxyphenyl)stearamide, l, 3-bis(4-hydroxyphenyl)propane, 2,4-bis(4-hydroxyphenyl)-4-methylpentane, l, 3-di[
2-(4-hydroxyphenyl)-2-propyl]benzene, 1,3-di[2-(3,5-dimethyl-4-hydroxyphenyl)-2-probylcobenzene, bisphenol 1,1-bis( Bis(hydroxyphenyl) acid compounds such as (hydroxyphenyl)-1-phenylethane (1-2) Sulfur-containing bisphenol color developer 4.4
'Dihydroxyphenyl diphenyl sulfone, 2.4'
Dihydroxyphenyl diphenyl sulfone, bis-(3
-allyl-4-hydroxyphenyl)sulfone, bis-
(3-allyl-4-hydroxyphenyl)sulfone, 3
- Bisphenolsulfone reading conductors such as 3'-sulfonylbis(4-hydroxybenzoic acid methyl ester), 1,3-bis(p-hydroxyanilinosulfonyl)benzene; 4-hydroxy-4'-benzyloxydiphenylsulfone, 4 -monoethers of bisphenolsulfones such as hydroxy-4'-isopropoxydiphenylsulfone; bis(3,5-dimethyl-4-hydroxyphenyl)sulfide, bis(2methyl-5-isopropyl-4-hydroxyphenyl)sulfide, 4 .4'-
Thiobis(G-ter-butyl-3-methylphenol), 1,5-di(4-hydroxyphenylthio)-3-
Oxybencune, l,8-di(4-hydroxythio)-
3,6-Sioxaoctane, ■,3-di(4-hydroxyphenylthio)acetone, l,7-di(4-hydroxyphenylthio)-3,5-dione, l,2-di(4-
Hydroxyphenylthio)phenylethane, l,2-di(4-hydroxyphenylthio)-1-(4-chlorophenyl)ethane, methyl 4-hydroxyphenylthio-4-hydroxyphenyl)acetate, bis(4-hydroxyphenylthio) ) Bisphenol sulfide such as methyl acetate, 4-benzyloxyphenyl-4-hydroxyphenyl sulfide; (2) Hydroxyarylcarboxylic acid color developer (2-1
) Hydroxybenzoic acid color developer p-hydroxybenzoic acid, enteric-hydroxybenzoic acid, salicylic acid, methyl p-hydroxybenzoate, benzyl p-hydroxybenzoate,
p-hydroxybenzoic acid-β-p-methoxyphenoxyethyl, p-hydroxybenzoic acid-β-phenoxyethyl, p-hydroxybenzoic acid-β-p-methoxyphenoxyethyl, p-hydroxybenzoic acid-2-(o- Hydroxybenzoic acid and p-hydroxybenzoic acid esters such as hydroxyphenylthio)ethyl; octadecyl 2,4-dihydroxybenzoate, β-p-ethoxyphenoxyethyl 2,4-dihydroxybenzoate, 2,4
-β-methallyloxyethyl dihydroxybenzoate,
2,4-dihydroxybenzoic acid-β-ethyloxyethyl, 2,4-dihydroxy-β-phenylthioethyl,
Hydroxybenzoic acid derivatives (2-2) such as 1,4-cyclohexanedimethanol-bis-(p-hydroxybenzoic acid) ester and 1,4-ethylene glycol-bis-(p-hydroxybenzoic acid) ester. Color agent salicylic acid metal salt (Z nl M L Cal
A I ), 4-tetradecyloxysalicylic acid, 4-
β-p-)lyoxyethoxysalicylic acid, 315-di(α-methylbenzyl)salicylic acid, 3,5-di(α
, α-dimethylbenzyl)salicylic acid, 3,5-di-t
er-butylsalicylic acid, 3-isopropenyl-5-t
er-butylsalicylic acid, 3-vinyl-5-cyclohexanoic acid, 3vinyl-5-benzylsalicyl9.5-myristoylsalicylic acid, 5-phenylacetylsalicylic acid, methylphenoxyacetylsalicylic acid, 4-myristoylaminosalicylic acid, 4-phenylacetylamino Salicylic acid, 2゜2-bis(3-carboxy-4-hydroxyphenyl)propane, 1,4-bis(3-carboxy-4-hydroxycumyl)benzene, bis(2-hydroxy-3-carboxy-5-α) Salicylic acid derivatives such as -phenethylphenyl)methane (2-3) Other hydroxyarylcarboxylic acid color developers 4-Hydroxyphthalate dimethyl, 3,4,5. l1i
-zinc salt of mono-2-hydroxyethyl tetrachlorophthalate, 3.4. S, phthalic acid derivatives such as the zinc salt of mono-3-hydroxy-2,2-dimethylpropyl 8-tetrachlorophthalate, p-chlorobenzyl gallate, hensyl gallate, p-vinylbenzyl gallate Gallic acid derivative; 1-hydroxy-4-benzyloxy-2-naphthoic acid, 1-acyloxy-4-benzyloxy-2-naphthoic acid, 2-acyloxy-4-
benzyloxy-1-naphthoic acid, Z n of these acids
Naphthoic acid derivatives such as polyvalent metal salts such as 2Mg; (2-4) Other carboxylic acid color developers 0-methyl fumarate, p-methyl fumarate, 0-ethyl fumarate,
p-benzyl fumarate, 0-naphthylmethyl fumarate,
Zinc indole-2-carboxylate, calcium indole-2-carboxylate, zinc l-methylindole-2-carboxylate, zinc p-nitrobenzoate, p-nitrobenzoic acid moiety, ascorbic acid, etc. (3) Sulfone Color developer methyl 4-hydroxybenzenesulfonate, ethyl 4-hydroxy-3-methyl-5-bromobenzenesulfonate, ethyl 4-hydroxy-3,5-dibromobenzenesulfonate, 4-hydroxy-41-methyldiphenyl Sulfone, 3', 4')rimethylene-4-hydroxydiphenylsulfone, 2-(4-hydroxybenzenesulfonyl)naphthalene, 1-(4-hydroxybenzenesulfonyl)naphthalene, 3-allyl-4-hydroxy-
4'~methyldiphenylsulfone, 3-allyl-4-hydroxy-4'-methquine diphenylsulfone, 3-allyl-4-hydroxy-4°-(2-phenoxyethoxy)diphenylsulfone, 3,4-dihydroxyphenyl -p-tolylsulfone, 2,2'-bis(4-hydroxybenzenesulfonyl)ethyl ether, 4-hydroxy-4'-isopropoxydiphenylsulfone, 4-
Hydroxy-4'-chlorodiphenyl sulfone, 3.5
-di-β-phenoxyethoxycarbonylbenzenesulfonic acid, 2-β-naphthoxyethoxynaphthalene-6-
Sulfonic color developers such as sulfonic acid; N-benzenesulfonyl-■-aminophenol, N-(α-naphthalenesulfonyl)-open-aminophenol, 1I3-bis(
p-hydroxyanilinosulfonylbenzene, N-(2
-phenoxyethyl)-4-hydroxybenzenesulfonamide, N-(3-phenoxypropyl)-4-hydroxybenzenesulfonamide, N-(phenylsulfonyl)-p-toluenesulfonamide, n-butyl-N
-(o-carboxyphenylsulfonyl)-p-7 minobenzoate, N-(dimethylsulfamoyl)-p-
) Sulfonamide compounds such as luenesulfonamide and N,N'-diphenylsulfonamide; Sulfonyl chloride compounds such as α-naphthalenesulfonyl chloride and p-phenylbenzenesulfonyl chloride These color developers may be used alone or in combination of two or more. May be used.

In the heat-sensitive recording material of the present invention, the amount of compound (A) represented by general formula (1) used is usually 1 to 200 parts by weight, preferably 3 to 300 parts by weight, based on 100 parts by weight of the color developer. Particularly preferably, the amount is in the range of 10 to 70 parts by weight. If the amount of compound (A) used is less than 1 part by weight, the effect of improving sensitivity in thermal recording is poor, and if it exceeds 200 parts by weight, the effect of improving sensitivity is already saturated and is uneconomical.

The usage ratio of color former and color developer is 1.0 parts by weight per 100 parts by weight of color former. The color developer is usually 5 to 100 parts by weight, preferably 1
0 to 70 parts by weight, particularly preferably 20 to 50 parts by weight. When the amount of the color developer used is less than 5 parts by weight, the desired color density cannot be obtained, and when it exceeds 100 parts by weight, the color density reaches an equilibrium and it is no longer economical to use any more.

Next, a method for producing the heat-sensitive recording material of the present invention will be described.

Compound (A), a color former, and a color developer are separately dispersed to produce a suspension solution. Next, mix each suspension solution,
The mixture (coating liquid) is applied to a support to produce a heat-sensitive recording material.

In detail, the compound (A) and the binder, the color former and the binder, and the color developer and the binder are each mixed in water with a surfactant (2-ethylhexylsulfosuccinate soda salt, naphthalenesulfonic acid), if necessary. 10 μ or less, preferably 3
Pulverize and disperse into particles smaller than μ to make a coating liquid.

Examples of the binder include polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose; sodium polyacrylate, polyvinylpyrrolidone, acrylic amide/acrylic ester copolymer, Acrylic acid amide/acrylic ester/methacrylic acid terpolymer, styrene/maleic anhydride copolymer alkali salt, imbutylene/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 acid ester, vinyl chloride/vinyl acetate copolymer, and Latex such as butyl methacrylate, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer, etc. can be used.

The coating solution is prepared by combining suspension solutions of each compound as shown in Table 1 below.

Table 1 The mark 0 in Table 1 means that, for example, coating liquid (b) is a mixture of a suspension solution of compound (A) and a suspension solution of a color former.

Further, each coating liquid may contain, if necessary, auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers, thermofusible substances, lubricants, and the like. Examples of fillers include calcium carbonate, warping force, zinc oxide,
In addition to fine inorganic powders such as titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, kaolin, talc, and surface-treated calcium carbonate and silica, urea/
Examples include organic fine powders such as formalin resin, styrene/methacrylic acid copolymer, and polystyrene resin. Examples of thermofusible substances and lubricants include higher fatty acids or their esters, amides, or metal salts, as well as various waxes, condensates of aromatic carboxylic acids and amines, benzoic acid phenyl esters, higher linear glycols, Examples include dialkyl 3,4-epoxy-hexahydrophthalate, higher ketones, and other thermofusible substances having a melting point of about 50 to 200°C.

Examples of the support include paper, synthetic paper, and synthetic resin film, with paper being preferred.

As a coating method, the following methods (I) to (■) can be used. That is, the coating liquids (a) to (g) are applied to the support.
) can be coated using a method such as an air knife coater, blend coater, roll coater or wipe press to form a heat-sensitive recording layer.

(I) Coating the coating liquid (a) onto the support. FIG. 1 shows the heat-sensitive recording material obtained. In FIG. 1, 1 is a support, and 2 is a layer containing a mixture of compound (A), a color former, and a color developer.

(n) Coating the coating liquid (d) on the support, and further coating the coating liquid (e) on top of the coating liquid (d). FIG. 2 shows the heat-sensitive recording material obtained. In FIG. 2, 5 is a layer containing a mixture of a color former and a color developer, and 6 is a layer of compound (A).

(I [I) Coating liquid (e) is coated on the support, and coating liquid (d) is further coated on the upper layer. FIG. 3 shows the heat-sensitive recording material obtained. In Figure 3, 6 is a compound (A
), layer 5 is a layer containing a mixture of a color former and a color developer.

(mV) Coating solution (g), coating solution (e), and coating solution (f) are coated on the support in a layered manner. FIG. 4 shows the heat-sensitive recording material obtained. In FIG. 4, 8 is a color developer layer, 6 is a compound (A) layer, and 7 is a color former layer.

(V) Coating liquid (f), coating liquid (e), and coating liquid (g) are sequentially layered on the support. The obtained thermosensitive recording material is shown in FIG. In FIG. 5, 6 is a layer of compound (A), 7 is a layer of color former, and 8 is a layer of color developer.

(Vl) Coating liquid (b) is coated on the support, and coating liquid (C) is further coated on top of the coating liquid (b). The obtained thermosensitive recording material is shown in FIG. In Figure 6, 3 is compound (A)
4 is a layer containing a mixture of compound (A) and a color developer, and 4 is a layer containing a mixture of compound (A) and a color developer.

(■) Coating liquid (c) is applied onto the support, and coating liquid (b) is further applied on top of the coating liquid (c). The obtained thermosensitive recording material is shown in FIG. In FIG. 7, 4 is a layer containing a mixture of compound (A) and a color developer, and 3 is a layer containing a mixture of compound (A) and a color former.

Preferred coating methods and heat-sensitive recording materials are (II) (V
l) and (■).

The coating thickness of each layer is determined depending on the form of the heat-sensitive recording material and other conditions. The coating amount is not particularly limited, but is usually 0.5 to 20 g/ra', preferably 1 to 15 g/ra', particularly preferably 3 to IO g/m in terms of dry weight.
It is 2.

[Examples] The present invention will be further described below with reference to Examples, but the present invention is not limited thereto. Parts and percentages in the examples are by weight. Further, the test methods in the examples are shown below.

(Test method) (+) Color development! ) Dynamic color development test The produced thermal recording paper was tested for the relationship between operating time (pulse width) and color density using an MSI type thermal head printing device. 0.1 to 1.0 m5ec, voltage 22Y0 Color density was determined by measuring reflection density using a Macbeth densitometer (manufactured by Macbeth). The larger the value, the higher the color density.

2) Static color development test The prepared thermal recording paper was heated using a thermal gradient heat sealer at a temperature range of 70°C to 100'C and a printing pressure of 2 kg/crs.
l The color was developed under the conditions of 2 seconds of pressure bonding time and the color density was measured. Same as t1 degree 1).

(2) Whiteness (background fog) Hunter white discoloration before coloring of thermal recording paper, B value is Mu
ltl 5pectro Co1our Meter
1 using H5C-2 type! II+ determined. The larger the value, the higher the degree of whiteness.

(3) Light resistance The colored image area in the color development test was irradiated for 972 hours at 80°C using a fade meter, and the color density of the irradiated area was measured. The densitometer is the same as I).

(4) Moisture resistance test Color developed image area at 45℃, 90% R1 (
After being left in a constant temperature and humidity chamber for 24 hours, the color density of the image area was measured. The concentration meter is the same as 1).

(5) Plasticizer Resistance Test A plastic eraser was placed on the image area that had been colored in the color development test, and after being left for 24 hours, the color density of the image area was measured. Same as densitometer beam.

Examples 1 to 3, Comparative Examples 1 to 3 Each of the following liquids A, B, or C was ground and dispersed in a ball mill for 24 hours, and then each layer was thoroughly mixed to prepare coating liquids I to H. This coating liquid was applied to high-quality paper (basis weight 50 g/m
The film was coated with a doctor blade so that the dry solid molecules tH;
3) was created.

As Comparative Examples 1 to 3, comparative sensitizer suspension solutions H-1, H-2 and H-3 (conventional compound suspensions) were used instead of the suspension solution of the sensitizer of the present invention in Solution A. Thermal paper (Comparative Examples 1 to 3) was prepared in the same manner using the same solution.

Table 2 [Liquid A: Sensitizer suspension solution (parts) Compound (4) (conventional product); 0°1・℃0 Compound (5) (conventional product); ) (conventional product); Compound (7); Calcium carbonate compound (8); Hydroxyethylcellulose (5%
Aqueous solution) [Liquid B: Color former suspension solution 3-(N-ethyl N-pentylamino-6-methyl-7
-Anilinofluorane [S-205 manufactured by Yamada Chemical Co., Ltd. 10 parts Hydroxyethyl cellulose 40 parts (5% aqueous solution) Water
50 parts [Liquid C: Color developer suspension solution Cobisphenol A Calcium carbonate polyvinyl alcohol (5% aqueous solution) Water table-3 [Coating liquid 30 parts 10 parts 40 parts 20 parts (parts) [Recording paper performance coefficient Table 4 Dynamic coloring test table 5 Static coloring test table 6 As is clear from Tables 4 to 6, the coloring properties of the thermal recording paper of the present invention are different from that of the conventional thermal recording paper (Comparative Examples 1 to 3). It was better. The light resistance, moisture resistance, and plasticizer resistance of the thermal recording paper of the present invention were superior to those of conventional thermal recording papers (Comparative Examples 1 to 3).

Examples 4 to 6, Comparative Example 4 The following solutions D and E were ground in a ball mill for 24 hours.
After being dispersed, a coating solution was prepared. Apply this coating liquid to high-quality paper (basis weight B
og/m, methods (I), (Vl) and (■), that is, (I), apply a mixed solution (1/1 weight ratio) of liquid D and E to paper with a dry solid content of 8 g/m2. It was applied with a doctor blade and dried. For (VI), a coating solution was applied to paper using a doctor blade so that the dry solid content was J14 g/m2, and then coating solution E was similarly applied onto this layer and dried. (■) is the opposite of (VI), in which liquid E was applied first, and then liquid D was applied. The coating amount was the same as (Vl).

[Liquid D: Mixed suspension solution of sensitizer and color former, colo-diethylamino-6-methyl 7-anilinofluorane
30 parts calcium carbonate
5 parts polyvinyl alcohol (5% aqueous solution) 35 parts water
40 parts [Liquid E: mixed suspension of sensitizer and color developer Copisphenol A
20 parts 1,5-di(4-hydroxyphenylthio)-
3-oxapentane
10 parts calcium carbonate 5 parts polyvinyl alcohol (5% aqueous solution) 35 parts water

Thermal recording papers prepared by the 25-part coating methods (I), (Vl) and (■) were designated as Examples 4.5 and 6, respectively.

Further, as Comparative Example 4, a thermosensitive recording paper (Comparative Example 4) was prepared by using parabenzylbiphenyl instead of compound (A) in Liquid D and Liquid E and applying the coating method in (r).

[Performance of recording paper Table 8 Static color development test table 9 As is clear from Tables 7 to 9, the color development of the thermal recording paper of the present invention is superior to that of the conventional thermal recording paper (Comparative Example 4). Ta. Lightfastness of the thermal recording paper of the present invention.

The moisture resistance and plasticizer resistance of conventional thermal recording paper (Comparative Example 4)
) was superior to the others.

Furthermore, among the coating methods, method (Vl) was the most excellent for producing heat-sensitive recording paper.

[Effects of the Invention] The heat-sensitive recording material containing the sensitizer of the present invention has significantly better coloring sensitivity and whiteness (background fog) than conventional materials.

Additionally, the image area provides high quality performance such as light fastness, moisture resistance and plasticizer resistance.

[Brief explanation of drawings]

FIGS. 1 to 7 are explanatory views (cross-sectional views) of the heat-sensitive recording material of the present invention. DESCRIPTION OF SYMBOLS 1... Support, 2... Layer containing a mixture of compound (A), a color former, and a color developer, 3... Layer containing a mixture of compound (A) and a color former, 4... Compound (A) ) and a color developer, 5... a layer containing a mixture of a color former and a color developer, 6... a layer of compound (A), 7... a layer of a color former, 8... a color developer. Agent layer diagram Figure 1 Figure 2

Claims (1)

[Claims] 1. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (1) [In the formula, R_1 and R_2 are aliphatic hydrocarbon groups having 4 or less carbon atoms; X is a carbonized group having 10 or less carbon atoms. A sensitizer comprising a compound (A) represented by the following formula: hydrogen group. 2. A thermosensitive recording material comprising an electron-donating colorless coloring agent and an electron-accepting color developing substance on a support and capable of developing color by heat melting, which contains the sensitizer according to claim 1. Recording materials. 3. The heat-sensitive recording material is a layer containing a mixture of an electron-donating colorless color former and an electron-accepting color developing substance on a support, and a layer of a compound (A) represented by general formula (1) is laminated thereon. The material according to claim 2, characterized in that it is made of. 4. A layer in which the heat-sensitive recording material is a mixture of a compound (A) represented by the general formula (1) and an electron-donating colorless coloring agent on a support;
3. The material according to claim 2, further comprising a layer containing a mixture of the compound (A) and an electron-accepting color developing substance. 5. A layer in which the heat-sensitive recording material is a mixture of a compound (A) represented by the general formula (1) and an electron-accepting color developing substance on a support;
3. The material according to claim 2, further comprising a layer containing a mixture of the compound (A) and an electron-donating colorless coloring agent.