JPH04112080A - Thermal recording material and sensitizer therefor - Google Patents

Abstract

PURPOSE:To prevent the lowering of color forming sensitivity in such a case that a lubricant is added and to enhance whiteness, light fastness, humidity resistance and plasticizer resistance by using a compound represented by a specific formula and solid at room temp. and having a specific solubility parameter as a sensitizer. CONSTITUTION:A sensitizer for a thermal recording material is composed of a compound represented by general formula R1-Y-CO-R2 (wherein R1 and R2 are a phenyl group, a naphthyl group, a tetrahydronaphthyl group or a group selected from these groups substituted with a 10 or less C hydrocarbon group and Y is 1-4C alkylene group or a 2-4C alkenylene group) and solid at room temp. and has a solubility parameter of 9.5-12. The thermal recording material containing this sensitizer is markedly enhanced in color forming sensitivity and generates no lowering of color forming sensitivity even when a specific metal salt of higher fatty acid (lubricant) is added and is also excellent in whiteness (background fog) and generates no lowering of whiteness even when the lubricant is added. An image part provides high-grade capacities such as light fastness, humidity resistance, plasticizer resistance or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a heat-sensitive recording sensitizer and a heat-sensitive recording material. More specifically, the present invention relates to a sensitizer for heat-sensitive recording paper and a heat-sensitive recording material such as heat-sensitive recording paper.

[Prior Art] In recent years, there has been a significant demand for faster information processing, and various high-speed devices have been developed. Along with this, there is a demand for highly sensitive heat-sensitive recording materials. Heat-sensitive recording materials such as heat-sensitive recording paper develop color by melting an electron-donating colorless coloring agent and an electron-accepting color-developing substance contained in a layer formed on a support such as paper with heat and causing the two to associate. It is made using the principle of

Conventionally, as a sensitizer to be used in combination with the above color forming agent and color developing substance to improve sensitivity, for example, a combination of sensitizers such as benzyl biphenyls (JP-A-82382-11
) 1l + Sensitizers such as 2-bis(phenoxy)ethane (JP-A-58588-1988), sensitizers such as P-nitroacetophenone (JP-A-84-40373), and deoxyanisoin (JP-A-84-40373). Kaihei 2-30584
Publication No. 2), etc. have been proposed.

[Problems to be Solved by the Invention] However, the color development sensitivity of heat-sensitive recording materials using these sensitizers is still insufficient, and in particular higher fatty acid metal salts such as zinc stearate and calcium stearate are used to prevent sticking. When such lubricants are added, there is a problem in that the coloring sensitivity decreases. Further, there is a problem in that side effects due to increased sensitivity, ie, decreases in whiteness, light resistance, moisture resistance, and plasticizer resistance, cannot be avoided.

[Means for Solving the Problems] The present inventors have arrived at the present invention as a result of intensive studies to solve these problems. That is, the present invention is based on the general formula % (1) [wherein R1 and R2 are phenyl group, naphthyl group, tetrahydronaphthyl group, or a group in which these are substituted with a hydrocarbon group having 10 or less carbon atoms, and Y is represents an alkylene group having 1 to 4 carbon atoms or an alkenylene group having 2 to 4 carbon atoms], is solid at room temperature, and has a solubility parameter of 3.5 to I2. a sensitizer for heat-sensitive recording; and a heat-sensitive recording material that contains at least an electron-donating colorless coloring agent and an electron-accepting color-developing substance in a layer formed on a support and that develops color under heat; The present invention is a heat-sensitive recording material characterized by containing the sensitizer described in 1 or 2 in a layer formed on a support.

In the present invention, among the groups represented by RI and R,
Specific examples of substituents constituting a group in which a phenyl group or a naphthyl group is substituted with a hydrocarbon group having a carbon number of IO or less include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and 5ec-butyl. ,tert
- Straight chain or branched alkyl groups such as butyl, pentyl, hexyl groups; Straight chain or branched alkenyl groups such as vinyl, allyl, propenyl, impropenyl groups; 2
- Straight chain or branched alkynyl groups such as butynyl, ethynyl, and 2-propynyl groups; aralkyl groups such as benzyl and phenethyl groups; aryl groups such as phenyl, tolyl, xylyl, biphenyl, naphthyl, and cumyl groups; and cyclohexyl groups, etc. Examples include cycloalkyl groups.

Among the groups representing RI and R2, preferred are phenyl, naphthyl, and groups substituted with methyl, phenyl, or cyclohexyl.

In general formula (1), RI and R2 may be the same or different. In addition, the above substituents may be plural, but
l substitution is preferred.

Among the groups representing Y in the present invention, examples of the alkylene group having 1 to 4 carbon atoms include alkylene groups such as methylene, ethylene, propylene, and butylene (these groups may be linear or branched) groups. Also, among the groups representing Y,
Examples of the alkenylene group having 2 to 4 carbon atoms include alkenylene groups such as vinylene (ethynylene) and flopenylene, with methylene, ethylene and vinylene groups being preferred.

Specific examples of the compound (A) [1 piece ~ [6] Shown below.

[1] Ketone compound compound from phenyl (naphthyl) acetic acid halide and (substituted) benzene (naphthalene) SP QCH2COO■, 02 QCHa C0QCHs 10.8BHs ○CFi*C0QC (CL h Qcn2coQcu, Q Qcn, C00O Qcn, COc+α +0.68 11.11 11.27 11.89 [Ketone compound compound from 2-core alkyl phenyl acetic acid halide and (substituted) benzene (naphthalene) 5P CHa QCH2COOIo, 8G CI+3 CHsQ CH2coQc ( cut )3CB3QCH
2cooc■20 CH2QCnsCOW C0QCHs COQω 10.16 10.99 10.30 10.78 etc. [3] Ketone compound compound from aralkyl phenyl (naphthyl) acetic acid halide and (substituted) benzene (naphthalene) Compound ○CH2QCH2co .

P 11.11 CHa CH3 [4Coarylphenyl(naphthyl)acetic acid halide and (
Ketone compound from benzene (naphthalene) (having a substituent) [ketone compound from 5-cocycloalkylphenyl (naphthyl) acetic acid halide and benzene (naphthalene) (having a substituent) Compound P Compound P σP Qcn2co○CH3 10,78 C庳DCH2CO○CHt○ 11.00 [6 Ketone compound compound from conaphthyl acetic acid halide and benzene (naphthalene) (with a substituent) P Solubility parameter (hereinafter abbreviated as SP) in the present invention What is cohesive energy density?
gy Denslty (hereinafter abbreviated as CHD)]. As shown below, this CED indicates the amount of energy required to evaporate 10 3 substances in a physicochemical manner.

(S P )”=CHD=ΔE/V=(ΔH-RT)/
VΔE: Evaporation energy (cal/Mok) ■Two molar capacity (am”/Mo#) △H: Latent heat of vaporization (ca
11 moles) R; gas constant (1,987ca11
Mol °k) T = Absolute temperature (°k) SP indicates the degree of polarity of the molecule, that is, the value of SP governs the thermodynamic properties of the solution, and from this value, solubility etc. can be quantitatively predicted or explained. SP
The calculation method is written by Robert F. Feders, "Polymer Engineering and Science J, 1974, 2.
It is described in "Solution and Solubility", Kozo Shinoda, published by Maruzen Co., Ltd., pages 92 to 10B, published in May, Volume 14, No. 2, or "Solution and Solubility" by Kozo Shinoda.

Each compound has an SP, and for electron-donating colorless coloring agents used in thermosensitive recording materials, for example, 2-anilino-3-methyl-6-1ethyl-N-
Isoamylaminofluorane is 11.50; 2-anilino-3-methyl-6-dinithylaminofluorane is 1
1.94; 2-7nilino-3-methylto-dibutylaminofluorane is 11.44; regarding electron-accepting color developing substances, for example, bisphenol A is 13. B4;
Bisphenol S is 1B, 94; salicylic acid benzyl ester is 12, 69; regarding lubricants, for example, zinc stearate is 9.18; aluminum stearate is 9.71; lead stearate is! +, 22; Cadmium stearate is 9.20.

As mentioned above, the SP of each of the electron-donating colorless coloring agent, the electron-accepting color developer, and the lubricant is quite different from each other, and it can be seen that they are difficult to respond to instantaneous dissolution by heat. Therefore, the sensitizer (solid solvent) that plays the role of mediating these dissolutions, that is, the compound (A
) is effective, first select those with SPs similar to these, such as electron-donating colorless color formers, electron-accepting color developers, lubricants, etc., and then select the sensitizer of the present invention having SPs similar to these. It is preferable to use one or more of these in combination.

Among the compounds (A) exemplified above, preferred are [1
], [2], [5] and [6] Particularly preferred are ketone compounds from phenylacetic acid halide and toluene, ketone compounds from phenylacetic acid halide and xylene, and phenylacetic acid. Ketone compounds from halide and biphenyl, ketone compounds from phenylacetic acid halide and cyclohexylbenzene, ketone compounds from phenylacetic acid halide and naphthalene, ketone compounds from phenylacetic acid halide and toluene, cyclohexylphenyl acetic acid halide Ketone compound from toluene, ketone compound from cyclohexylphenylacetic acid halide and cyclohexylbenzene, naphthyl acetate 7, ketone compound from ride and benzene, ketone compound from naphthyl acetate halide and toluene, naphthyl acetate halide and cyclohexylbenzene and a ketone compound from naphthyl acetate halide and naphthalene.

Among these, more preferred is a ketone compound made from phenylacetic acid halide and toluene.

The compound (A) in the present invention can be produced by any method. For example, the compound (A) can be produced by a Friedel-Crafts reaction from an acid chloride represented by the general formula R+ Y COCl and a hydrocarbon represented by the general formula Rs H. A)
can be obtained.

This Friedelta-rat reaction can be performed by a known method. For example, aluminum chloride, iron trichloride, tin tetrachloride, zinc chloride, boron fluoride, sulfuric acid, phosphorus pentoxide,
In the presence of a condensing agent such as phosphoric acid or hydrofluoric acid, the acid chloride and hydrocarbon are heated to 30 to 120°C and reacted. The reaction product is decomposed with cold water, solid insoluble matter is filtered; washed with water, dried, and then recrystallized with alcohol to obtain the compound (A).

In the present invention, the electron-donating colorless coloring agent (hereinafter abbreviated as coloring agent) is not particularly limited, and includes, for example, those used in known heat-sensitive or pressure-sensitive recording materials. Examples of the known coloring agents include triarylmethane-based, diphenylmethane-based, xanthine-based, phenothiazine-based, and spiropyran-based coloring agents.

Specific examples of triarylmethane coloring agents include 3.3
-Bis(p-dimethylaminophenyl)-trimethylaminophthalide (crystal violet lactone C
VL), 3,3-bis(p-dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl)
-3-(1,2-dimethylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(2
-methylindol-3-yl)phthalide, 3-(p-
dimethylaminophenyl)-3-(2-phenylindol-3-yl)phthalide, 3,3-bis(1,2-dimethylindol-3-yl)-5-dimethylaminophthalide, 3,3-bis- (2-dimethylindol-3-yl)-6-dimethylaminophthalide, 3,3-
Bis(3-ethylcarbazol-3-yl)-5-dimethylaminophthalide, 3,3-bis(2-phenylindol-3-yl)-5-dimethylaminophthalide, 3
-p-dimethylaminophenyl-3-(l-methylvirol-2-yl)-6-dimethylaminophthalide and the like.

As a diphenylmethane color former, 4,4'-bis-
Examples include dimethylaminobenzhydrin benzyl ether N-halophenyl leuco auramine and N-2.4.5-trichlorophenyl leuco auramine.

Examples of xanthine coloring agents include rhodamine-B-anilinolactam, rhodamine (p-nitroanilino)lactam, rhodamine (0-chloroanilino)lactam, and 3-
Diethylamino-7,8-benzofluorane, Rhodamine-B-(P-chloroanilinolactam), 2-anilino-3-methyl-6-dimethylaminofluorane 2-anilino-3-methyl-GN- Ethylaminofluorane, 2-anilino-3-methyl-G-N-methyl-N-(
isopropyl)aminofluorane, 2-anilino-3-
Methyl-6-N-methyl-N-cyclohexylaminofluorane, 2-anilino-3-methyl-6-dinithylaminofluorane, 2-anilino-3-methyl-6-sibutylaminofluorane, 2-anilino -3-chloro-6
-dimethylaminofluorane, 2-anilino-3-methyl-〇-N-ethyl-N-isoamylaminofluorane, 2-anilino-3-chloro-6-dinithylaminofluorane, 2-anilino-3-chloro-11i -N-methyl-N-dithylaminofluorane, 2-anilino-3-
Chloro-Ei-N-methyl-N-(isopropyl)aminofluorane, 2-anilino-3-chloro-BN-methyl-N-cyclohexylaminofluorane, 2-anilino-3-chloro-6-N- Methyl-N-pentylaminofluorane, 2-(P-methylanilino)-3-methyl-8-dimethylaminofluorane, 2-(P-methylanilino)-3-methyl-6-N-methyl-N-ethylamino Fluoran, 2-(P-methylanilino)-3-
Methyl-6-N-methyl-N-(isopropyl)aminofluorane, 2-CP-methylanilino)-3-methyl-BN-methyl-N-pentylaminofluorane, 2
-(P-methylanilino)-3-methyl-N-methyl-N-cyclohexylaminofluorane, 2-(P-methylanilino)-3-methyl-〇-N-ethyl-N-pentylaminofluorane, 2-(P- methylanilino)
-3-chloro-6-diethylaminofluorane, 2-(
P-methylanilino)-3-Frolo-6-diethylaminofluorane, 2-(P-methylanilino)-3-chloro-G-N-methyl-N-ethylaminofluorane, 2
-(P-methylanilino)-3-chloro-6-N-methyl-N-(isopropyl)aminofluorane, 2-(P
-methylanilino)=3-chloro-6-N-methyl-N
-cyclohexylaminofluorane, 2-(P-methylanilino)-3-chloro-6-N-methyl-N-pentylaminofluorane, 2-CP-methylanilino)-3
-chloro-6-N-ethyl-N-pentylaminofluorane, 2-(P-methylanilino)-3-chloro-6-
N-methyl-N-furylmethylaminofluorane, 2-
Examples include (P-methylanilino)-3-ethyl-6-N-methyl-N-furylmethylaminofluorane.

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'-cyclospirodinaphthopyran, 3-
Examples include benzyl-spiro-dinaphthopyran, 3-methyl-naphtho-(3-methoxy-benzo)-spiropyran, and 3-probyl-spiro dibenzodipyran.

As an indolylphthalide coloring agent, 3,3-bis(
1-Ethyl-2-methylindol-3-yl)phthalide, 3,3-bis(l-octyl-2-methylindol-3-yl)phthalide, 3-(2-ethoxy-4-diethylaminophenyl)-3 -(1-ethyl-2-methylindol-3-yl)phthalide, 3-(2-ethoxy-4-dibutylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)phthalide, 3 −(
2-amyloxy-4-diethylaminophenyl)-3
-(+-Ethyl-2-methylindol-3-yl)phthalide, 3-(2-ethoxyle-4-diethylaminophenyl)-3-(1-octyl-2-methylindole-
Examples include 3-yl) phthalide.

Examples of pyridine-based coloring agents include 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-octyl-2-methylindol-3-yl)-7-azaphthalide, 3-
(2-ethoxy-4-diethylaminophenyl)-3
-(1-ethyl-2-methylindol-3-yl)-
Examples thereof include 4-azaphthalide, 3-(2-hexyloxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide, and the like.

Examples of fluorene color formers include 3',6°-bisdiethylamino-5-diethylaminospiro(inbenzofuran-1,9-fluorene)-3'-one, 3',6'-bisdiethylamino-7-diethylamino-2- Methylspiro(1,3-benzoxazine-4,9'-fluorene)-3'-one 31. Examples include G+-bisdiethylamino-twodiethylaminospiro(2-hydro-1,3-benzoxazin-4,9'-fluorene)-2-one.

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

On the other hand, as the electron-accepting color-developing substance (hereinafter abbreviated as a color-developing agent), various electron-accepting color-developing substances that react with a color former when heated to develop color can be used. Examples of such color developers include phenolic substances, organic or inorganic acidic substances, and salts thereof.

Specific examples include "Paper and Pulp Technology Times, Chic Time Co., Ltd., Vol. 30, No. 6 to Vol. 31, No. 3"
``Color developer for thermal recording paper (1) - (complete), written by Takashi Shiga'' serialized in ``Color developer for thermal recording paper (1) - (complete),'' written by Takashi Shiga, and ``Color developer for thermal recording paper (1)'' published in ``Volume 32, No. 4 to Vol. 32, No. ) ~ (complete), written by Takashi Shiga”
These include those listed in . Specifically, the following can be mentioned.

(1) Bisphenol color developer (1-1) Non-sulfur-containing bisphenol color developer 2-(4
-hydroxyphenyl)propane, 2-(3'-hydroxyphenyl)propane, tetrabromobisphenol A14.4'-isopropylidenediphenol, 4,4
Bisphenol A derivative compounds such as '-butylidenebis (2-t-butyl-5-methylphenol), 4.4
'-Methylenebis(2-cyclohexyl-5-methylphenol), 4,4'-isopropylidenebis(2-cyclohexyl-5-methylphenol), 4,4'-butylidenebis(2-cyclohexyl-5-methyl phenol), 4,4'-cyclohexylidenebis(2-cyclohexyl-5-methylphenol), 3,3-bis(
Ethyl 3-cyclohexyl-4-hydroxy-5-methylphenol)butanoate, 4-[:1,1-bis(4-
hydroxyphenyl)ethyl]biphenyl, 2-[1,
1-bis(4-hydroxyphenyl)ethylconaphthalene, phenyl-1,1-bis(4-hydroxyphenyl)butane, 1,1-bis(p-hydroxyphenyl)cyclohexane, 4,4'-butylidene bis(2 -cyclohexyl-5-methylphenol), bisphenol A related compounds such as methyl-phenyl-methylidene bisphenol, 1, t-bis(4-hydroxyphenyl)acetic acid, 2,2-bis(4-hydroxyphenyl)propionic acid , bis(4-hydroxyphenyl)acetic acid methyl ester, bis(4-hydroxyphenyl)-n-butyl acetate, bis(4-hydroxyphenyl)propargyl acetate, bis(4-hydroxyphenyl)acetate cinnamyl, bis(4-hydroxyphenyl)acetate hydroxyphenyl)acetate, bis(4-hydroxyphenyl)acetate% phenyl, bis(4-hydroxyphenyl)phenethyl acetate, bis(4-hydroxyphenyl)acetate, bis(4-hydroxyphenyl)acetate,
-hydroxyphenyl)acetate-β-(4'-ethoxyphenoxy)ethyl, 2.2-bis(4-hydroxyphenyl)acetate-3-phenoxypropyl, 2゜2-bis(
4-hydroxyphenyl)valerate-β-(4'-methylphenoxy)ethyl, bis(4-hydroxyphenyl)
Stearic acid amide, 1,3-bis(4-hydroxyphenyl)propane, 2,4-bis(4-hydroxyphenyl)-4-methylpentane, l,3-di[2-(4-
hydroxyphenyl)-2-propylcobenzene, 1,
3-di[2-(3,5-dimethyl-4-hydroxyphenyl)-2-propylcobenzene, bisphenol 1
．． Bis(hydroxyphenyl) acid compounds such as 1-bis(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, 3-3'
- Bisphenolsulfone derivatives such as sulfonylbis(4-hydroxybenzoic acid methyl ester) and 1,3-bis(p-hydroxyanilinosulfonyl)benzene;
Monoethers of bisphenolsulfones such as 4-hydroxy-4'-benzyloxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone; bis(3,5-dimethyl-4-hydroxyphenyl)sulfide, bis(2- Methyl-5-isopropyl-
4-hydroxyphenyl) sulfide, 4,4'-thiobis(B-ter-butyl-3-methylphenol),
1. S-di(4-hydroxyphenylthio)-3-
Oxypentane, l,8-di(4-hydroxythio L-
3. li-dioxaoctane! , 3-di(4-hydroxyphenylthio)acetone, ! , 7-di(4-hydroxyphenylthio)-3,5-dione, 1,2-di(4
-Hydroxyphenylthio)phenylethane, 1,2-
Di(4-hydroxyphenylthio)-1-C4-chlorophenyl)ethane, 4-hydroxyphenylthio-4-
(2) Hydroxyarylcarboxylic acid color developer (2-1
) Hydroxybenzoic acid color developer p-hydroxybenzoic acid, ■-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, 2.4-β-p-ethoxyphenoxyethyl dihydroxybenzoate, 2.4
-dihydroxybenzoic acid-β-methallyloki/ethyl,
2,4-dihydroxybenzoic acid-β-ethyloquinethyl, 2,4-dihydroxy-β-phenylthioethyl,
1. Hydroquine benzoic acid derivatives such as 4-7 chlorhexanedimethanol bis(p-hydroxybenzoic acid) ester, 4-ethylene glycol-bis(p-hydroxybenzoic acid) ester, etc. (2-2) Salicylic acid color developer Salicylic acid metal salt (Z n1M g+ Cal A
l ), 4-tetradecyloxysalicylic acid, 4-β
-p-trioxyethoxysalicylic acid, 3,5-di(
α-methylbenzyl)salicylic acid, 3,5-di(α,
α-Dimethylbenzilic acid, 3-impropenyl-5-ter-butylsalicylic acid, 3-vinyl-5-cyclohexanoic acid, 3-vinyl-5
-Benzylsalicylic acid, 5-myristoylsalicylic acid,
5-phenylacetylaminosalicylic acid, methylphenoxyacetylsalicylic acid, 4-myristoylaminosalicylic acid, 4-phenylacetylaminosalicylic acid, 2.

2-bis(3-carboxy-4-hydroxyphenyl)
Salicylic acid derivatives such as propane, l,4-bis(3-carboxy-4-hydroxycumyl)benzene, bis(2-hydroxy-3-carboxy-5-α-phenethylphenyl)methane, etc. (2-3) Other Hydroxyarylcarboxylic acid color developer Dimethyl 4-hydroxyphthalate, 3,4,5,6-tetrachlorophthalic acid-mono-2-hydroxyethyl zinc salt, 3,4,5,[i-tetrachlorophthalic acid- Phthalic acid derivatives such as the zinc salt of mono-3-hydroxy-2,2-dimethylpropyl, gallic acid derivatives such as p-chlorobenzyl gallate, benzyl gallate, p-vinylbenzyl gallate; l-hydroxy-4 -benzyloxy-2-naphthoic acid, l-acyloxy-4-benzyloxy-2-naphthoic acid, 2-acyloxy-4-benzyloxy-1-naphthoic acid, Z no of these acids
Naphthoic acid derivatives such as polyvalent metal salts such as Mg (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 1-methylindole-2-carboxylate, zinc p-nitrobenzoate, p-nitrobenzoic acid moiety, L-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-4'-methyl Diphenyl, sulfone, 3',4') dimethylene-4-hydroxydiphenylsulfone, 2-(4-hydroxybenzenesulfonyl)naphthalene, 1-(4-hydroxybenzenesulfonyl)naphthalene, 3-allyl-4-hydroxy-4 '-Methyldiphenylsulfone, 3-allyl-4-
Hydroxy-4'-methoxydiphenyl sulfone, 3-
Allyl-4-hydroxy-4'-(2-phenoxyethoxy)diphenylsulfone, 3,4-dihydroxyphenyl-9-)lylsulfone, 2,2'-bis(4-hydroxybenzenesulfonyl)ethyl ether, 4-hydroxy- 41-isopropoxydiphenyl sulfone,
4-Hydroxy-4'-chlorodiphenylsulfone, 3
, 5-di-β-phenoxyethoxycarbonylbenzenesulfonic acid, 2-β-naphthoxyethoxynaphthalene-
Sulfonic color developers such as 6-sulfonic acid; N-benzenesulfonyl-1-aminophenol, N-(α-naphthalenesulfonyl)-11-aminophenol,! ,3-
Bis(p-hydroxyanilinosulfonylbenzene, N
-(2-phenoxyethyl)-4-hydroxybenzenesulfonamide, N-(3-phenoxypropyl)-4
-Hydroxybenzenesulfonamide ζ N-(phenylsulfonyl)-p-)luenesulfonamide, n-butyl-N-(o-carboxylphenylsulfonyl)-
Sulfonamide compounds such as p-aminobenzony), N-(dimethylsulfamoyl)-p-toluenesulfonamide, and N,N'-diphenylsulfonamide:
These color developers, such as sulfonyl chloride compounds such as α-naphthalenesulfonyl chloride and p-phenylbenzenesulfonyl chloride, may be used alone or in combination of two or more.

In the present invention, when the above grade fatty acid metal salt is used as a lubricant, examples of the grade fatty acid metal salt include calcium salts, magnesium salts, lead salts, cadmium salts, barium salts of higher fatty acids such as balmitic acid, stearic acid, and behenic acid; Examples include aluminum salts, with zinc salts and aluminum salts being particularly preferred.

In the heat-sensitive recording material of the present invention, the amount of the sensitizer of the present invention used is usually 1 to 200 parts by weight, preferably 3 to 100 parts by weight, particularly preferably 1 to 100 parts by weight.
It is 0 to 70 parts by weight. If the amount of the sensitizer used is less than 1 part by weight, the effect of improving sensitivity as a thermosensitive recording will decrease, and the
If the amount exceeds parts by weight, the sensitivity improvement effect is already saturated and it is uneconomical.

The ratio of the color former to the color developer is usually 5 to 100 parts by weight, preferably 10 to 70 parts by weight, particularly preferably 20 to 50 parts by weight per 100 parts by weight of the color former. . If the amount of the color developer used is less than 5 parts by weight, the color density will decrease, and if it exceeds 10 (1 part by weight), the color density will reach equilibrium and it is uneconomical to use more than this.

The amount of the higher fatty acid metal salt of the present invention used is usually 100 parts of the color developer.
Usually 5 to 300 parts by weight, preferably 1 part by weight
It is 0 to 200 parts by weight. If the amount of higher fatty acid metal salt used is less than 5 parts by weight, the anti-sticking property is poor;
Moreover, if it exceeds 300 parts by weight, thermal head residue will increase, which is not preferable.

The coating solution is applied to the support using a method such as an air knife coater, blade coater, roll coater, or wipe press.

Next, a method for producing the heat-sensitive recording material of the present invention will be illustrated. A suspension solution containing a sensitizer, a color former, and a developer is prepared. Subsequently, a heat-sensitive recording material is produced by applying each of the suspension solutions alone or in combination according to various coating methods to a support as a coating solution.

An example of how to prepare each suspension solution is to prepare a sensitizer and a binder, a color former and a binder, a color developer and a binder in water, and optionally a surfactant (2-ethylhexyl sulfosuccinate soda salt, naphthalene, etc.). (sulfonic acid sodium salt formalin condensate, etc.) using a pulverizer such as a ball mill, atrider, or sand grinder to obtain each suspension solution.

Examples of the binder include polyvinyl alcohol,
Starch and its derivatives, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose; sodium polyacrylate, polyvinylpyrrolidone, acrylic amide/acrylic ester copolymer,
Acrylic acid amide/acrylic ester/methacrylic acid terpolymer, styrene/maleic anhydride copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, etc. In addition to water-soluble polymers, polyvinyl acetate, polyurethane, styrene/butadiene copolymer, polyacrylic acid, polyacrylic ester, vinyl chloride/
Latex such as vinyl acetate copolymer, polybutyl methacrylate, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer, etc. can be used.

As shown in Table 1 below, the coating solution may be a mixture of three suspension solutions, a mixture of two solutions, or a single solution, depending on the various coating methods.

Table 1 Note) Mark 0 indicates the suspension solution constituting each of coating solutions a to g.

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, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay kaolin, talc, and surface-treated inorganic fine powders such as calcium carbonate and silica, as well as urea. / Formalin resin, styrene/methacrylic acid copolymer, polystyrene resin, and other fine powders. Examples of thermofusible substances include higher fat 1m2 amides such as stearic acid amide, stearic acid methylene bisamide, oleic acid amide, and coconut fatty acid amide, bisamides such as ethylene bisstearylamide, N-decyl-N
Urea-based compounds such as '-lauryl urea and tostearyl-r-tocosyl urea, waxes such as stearic acid, polyethylene, carnauba wax, beeswax, paraffin wax, and other known thermofusible substances having a melting point of 50 to 200°C Things can be given.

For example, the coating solution can be applied to the support using an air knife coater or a blade coater.
Coating is done by a method such as a roll coater or wipe press. Further, as a method for forming the heat-sensitive recording layer, for example, the heat-sensitive recording layer may be formed by the following methods (I) to (■) in which the combinations selected from coating liquids a to g shown in Table 1 are changed. can.

(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 a sensitizer, 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 forming agent and a color developer, and 6 is a layer containing a sensitizer.

(III) Coating liquid (e) is applied onto the support, and coating liquid (d) is further applied on top of the coating liquid (e). FIG. 3 shows the heat-sensitive recording material obtained. In FIG. 3, 6 is a layer of a sensitizer, and 5 is a layer containing a mixture of a color former and a color developer.

(IV) 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 sensitizer layer, and 7 is a color former layer.

(Coating solution (f), coating solution (e), and coating solution (g) are coated on the Vl support in a layered manner in this order. The obtained heat-sensitive recording material is shown in FIG. 5. In FIG. 5, 6 is a sensitizer layer, 7 is a color former layer, and 8 is a color developer layer.

(VI) 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 FIG. 6, 3 is a layer containing a mixture of a sensitizer and a color former, and 4 is a layer containing a mixture of a sensitizer 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 in which a sensitizer and a color developer are mixed, and 3 is a layer in which a sensitizer and a color former are mixed.

Among these, preferred method for forming a thermosensitive recording layer (II)
(VI) 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 the dry weight is usually 0.5 to 20 g//, preferably 1 to 15 g/$, particularly preferably 3 to 1 Og/s
It is 2.

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

(Test Methods) (1) Color development (■) Dynamic color development test The prepared thermal recording paper was tested for the relationship between operating time (pulse width) and color density using a 1151 type thermal head printing device. 0.1-1.0*+sec, voltage 22v0
The color density was determined by measuring the 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/cta.
l The color was developed under the conditions of 2 seconds of pressure bonding time and the color density was measured. The densitometer is the same as I).

(2) Whiteness (background fog) Hunter's white skin before coloring of thermal recording paper, B value is Mu
lti 5pectro Co1our Meter
Measurement was performed using N5C-2 type. The larger the value, the higher the degree of whiteness.

(3) Light resistance The colored image area in the color development test was irradiated with a xenon lamp at 30°C for 7 hours, and the color density of the irradiated area was measured. The densitometer is the same as l).

(4) Moisture resistance test Colored image area in color development test at 45℃, 90% R11
After being left in a constant temperature and humidity chamber for 24 hours, the color density of the image area was measured. The densitometer is the same as l).

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

Production Examples 1 to 6 and Comparative Production Examples 1 to 4 Each of the compounds shown in Table-2 was finely ground, and each compound shown in Table-2 (1
) were obtained as sensitizers of the present invention. In addition, sensitizers (1) to (phase) of Comparative Production Examples were each obtained by finely pulverizing each compound shown in Table 2 (2).

Table 2 (1) Table 2 (2) Comparative Examples 1 to 8 shown in Table 8 were carried out in the same manner as above except that
A coating liquid and a heat-sensitive recording material were prepared.

Tables 9 to 14 show the results of measuring each performance of the heat-sensitive recording materials of Examples 1 to 12 and Comparative Examples 1 to 8.

Examples 1 to 12, Comparative Examples 1 to 8 After pulverizing and dispersing the AA, BB (1), BB (2) and CC liquids shown in Tables 3 to 5 for 24 hours in a ball mill, each liquid was The combinations shown in -7 and 8 were thoroughly mixed to prepare coating liquids of Examples 1 to 12. This coating solution was applied with a doctor blade onto high-quality paper (basis weight 5 Gg/m) with a dry solid content of 1 g/■2, and after drying, Example 1
-12 heat-sensitive recording materials of the present invention were prepared.

In addition, the conventional sensitizer suspension solution and HH solution shown in Table 6 were used instead of the AA solution, and the combinations shown in Table 8 were used instead of the combinations shown in Table 7. ) ■ = Calcium carbonate @: 0% hydroxyethyl cellulose aqueous solution) Table 5 Table 4 Table 4 Table 6 Table 7 [Coating solution containing sensitizer of the present invention] Table 7 of the coating solution using the sensitizer of the present invention Table 9 Table of color density based on dynamic color development test -1 O Table of color density based on static color development test -1 Table - Dynamic color development Color Density Table Based on Static Color Test - 1 Color Density Table Based on Static Color Test - ■ Examples 13 to 15, Comparative Example 9 The DD and EE solutions in Tables 15 and 16 were ground and dispersed in a ball mill for 24 hours. A suspension solution was obtained.

Spread this solution on high-quality paper
, (V[) and (■) methods, that is, (I), a mixture of DD liquid and EE liquid (1/I weight ratio) is applied to paper using a doctor blade so that the dry solid content is 8 g/■2. Coated and dried. For (Vl), coat the coating liquid DD on paper with a doctor blade so that the dry solid content is 4 g 2,
Subsequently, coating liquid EE was similarly applied onto this layer and dried. (■) is the opposite of (Vl), in which the EE liquid was applied first, and then the DD liquid was applied. The coating amount was the same as (Vl).

As is clear from Tables 9 to 14, the whitening, color development, light resistance, moisture resistance, and plasticizer resistance of the thermal recording paper of the present invention were all superior to those of conventional thermal recording paper. In particular, white discoloration was high and dynamic color development was excellent.

Table - Table 16 Heat-sensitive recording materials prepared by coating methods (I), (VI) and (■) were designated as Examples 13.14 and 15, respectively.

In addition, as Comparative Example 9, benzyl-P of DD and EE liquids
- A heat-sensitive recording material (Comparative Example 9) was prepared by coating by the coating method (I) using P-benzylpyphenyl instead of methylphenylketone. Next, the performance of the heat-sensitive recording materials of Examples 13 to 15 and Comparative Example 8 was measured, and the results are shown in Tables 17 to 19.

Table - ■ Table - Dynamic color development test table-1 As is clear from the static color development test color density tables -13 to 15, the whitening color development, light fastness, moisture resistance, and resistance of the heat-sensitive recording material of the present invention. The plasticizer properties were superior to those of conventional heat-sensitive recording materials.

(Example 14) was the best.

[Effect of the invention] The thermal recording material of the invention containing the sensitizer of the invention has the following properties:
Extremely high color sensitivity, especially higher fatty acid metal salts (lubricant)
Even when added, the color development sensitivity does not decrease as in the conventional case. It also has excellent whiteness (background fog), and does not deteriorate even when a lubricant is added like in the past.

In addition, the image area provides excellent performance such as light resistance, moisture resistance, and plasticizer resistance.

Because of these effects, the sensitizer and heat-sensitive recording material of the present invention are useful for various recording materials such as facsimiles and POS labels.

[Brief explanation of drawings]

FIGS. 1 to 7 are explanatory views (cross-sectional views) of the heat-sensitive recording material of the present invention. 1...Support, 2...A layer containing a mixture of a sensitizer, a color former and a color developer, 3...A layer containing a mixture of a sensitizer and a color former, 4...A layer containing a mixture of a sensitizer and a color former. Calendar mixed with colorants,
5... Layer containing a mixture of color former and color developer 6... Layer of sensitizer, 7... Layer of color former, 8... Layer of color developer Fig. 1 Fig. 2

Claims (1)

[Claims] 1. General formula R_1-Y-CO-R_2 (1) [In the formula, R_1 and R_2 are substituted with a phenyl group, a naphthyl group, a tetrahydronaphthyl group, or a hydrocarbon group having 10 or less carbon atoms. group, Y has 1 to 4 carbon atoms
represents an alkylene group or an alkenylene group having 2 to 4 carbon atoms], is solid at room temperature, and has a solubility parameter of 9.5 to 12. Sensitizer. 2. A claim in which R_1 represents a phenyl group, tolyl group, cyclohexylphenyl group, or naphthyl group, R_2 represents a phenyl group, tolyl group, xylyl group, cyclohexylphenyl group, biphenyl group, or naphthyl group, and Y represents a methylene group. The sensitizer according to 1. 3. A heat-sensitive recording material which contains at least an electron-donating colorless color former and an electron-accepting color developing substance in a layer formed on a support and which develops color by heat, the sensitizer according to claim 1 or 2. 1. A heat-sensitive recording material comprising a layer formed on a support. 4. Claim 3, wherein the layer formed on the support is a laminated layer containing the electron-donating colorless coloring agent, the electron-accepting color-developing substance, and a sensitizer-containing layer. heat-sensitive recording material. 5. The layer formed on the support is a layer containing the sensitizer and the electron-donating colorless color former, and a layer containing the sensitizer and the electron-accepting color developing substance. The heat-sensitive recording material according to claim 3, which is a layer. 6. The layer formed on the support is a layer containing the sensitizer and the electron-accepting color developer, and a layer containing the sensitizer and the electron-donating colorless color former. The heat-sensitive recording material according to claim 3, which is a layer. 7. The heat-sensitive recording material according to any one of claims 3 to 6, wherein the layer formed on the support is a layer containing a higher fatty acid metal salt.