JPS62142683A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material having a sufficient developed color density and a sufficient color forming sensitivity, by incorporating an electron-donative colorless dye, an electron-acceptive compound and a heat- fusible substance. CONSTITUTION:A thermal recording material comprises an electron-donative colorless dye, an electron-acceptive compound and a heat-fusible substance of the formula, wherein R is an alkyl, aryl or acyl and X is a bivalent group. Typical examples of the heat-fusible substance include 1,4,-bis(2-hydroxy-4- methoxybenzoyloxy)butane and 1,8-bis(2-hydroxy-4-methoxybenzoyloxy)octane. This thermal recording material has a sufficient color forming sensitivity, and is capable of forming a developed color image which is so stable that discoloration or fading hardly occurs even under irradiation with light, heating or moistening for a long period of time. Therefore, a record formed can be preserved for a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Application of the Invention> The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material with improved color development and color image storage stability.

<Prior art> Akihiro Tokko developed a heat-sensitive recording material using an electron-donating colorless dye and an electron-accepting compound. -/≠No. 032, Special public show 1A3
−≠/Disclosed in Otsu No. 0, etc. The minimum performance that such a heat-sensitive recording material should have is (1) sufficient color density and color development sensitivity, (2) no fogging (color development phenomenon during storage before use), and (3) The coloring material must have sufficient fastness after coloring, but currently no product has been obtained that completely satisfies these requirements.

Especially in recent years, with the speeding up of thermal recording systems, the above (1)
Research is being carried out intensively.

In the 2J method, the melting point of the electron-accepting compound itself is set to 6
It may be changed from 0 to 1oo0c. However, it is difficult to control the melting point of phenolic compounds, which are electron-accepting compounds that are currently widely used.
In addition, the phenolic compound itself is expensive, making it impractical.

Other methods include the combined use of an organic acid and a phenolic compound as an electron-accepting substance, or the use of a compound having an alcoholic hydroxyl group. The use of polyvalent metal salts is described. It is also described that a copolymer of hydroxyethyl cellulose and maleic anhydride is used.

Also, Tokuko Akihiro/-276 Tata and Tokukai Akihiro! -/ri 23/ issue describes the addition of warakun ode.

In addition, JP-A ≠ 2-3 ≠ r ≠ λ, JP-A ≠ ter//1
J6 Hiro issue, JP-A-1989-/≠23j-3, JP-A-12-
1047≠No. 6, JP-A No. 33-J"AJlI, JP-A No. 1031-/1031p, JP-A No. 33-≠♂71/,
and Japanese Unexamined Patent Publication No. 72-72, etc., containing compounds such as thioacetanilide, phthalonitrile, acetamide, di-β-naphthyl-p-phenylenediamine, fatty acid amide, acetoacetanilide, diphenylamine, penzamide, carbazole, etc. Nitrogen organic compounds or thermofusible substances such as -23-di-m-tolylbutane, ≠, ≠'-dimethylbiphenyl, or dimethyl isophthalate,
It has been described that carboxylic acid esters such as diphenyl heptatarate, dimethyl terephthalate, etc. are added as sensitizers. Also, British patent publication λ, 07≠,
No. 333 describes the addition of hindered phenols.

However, heat-sensitive recording materials produced using these methods are insufficient in color density and color sensitivity.

<Object of the Invention> Therefore, an object of the present invention is to provide a heat-sensitive recording material which has sufficient color density and color development sensitivity and satisfies other requirements.

<Structure of the Invention> The object of the present invention has been achieved by a heat-sensitive recording material containing a captive electron-donating colorless dye, (1) an electron-accepting compound, and a thermofusible substance represented by the following general formula (1).

In the above formula, R is an alkyl group, an aryl group, or an acyl group VX
represents a divalent group.

These alkyl groups, aryl groups, and acyl groups may have substituents, and examples of substituents include alkyl groups, alkoxy groups, aryl groups, acyl groups, aryloxy groups, substituted amino groups, halogen atoms, etc. can be given.

Among the substituents represented by R in the above general formula ([), an alkyl group having a carbon atom number of /~/l, a carbon atom number of 6~/l,
A male aryl group and an acyl group having 2 to 10 carbon atoms are preferred, particularly an alkyl group having 10 to 10 carbon atoms, an aryl group having 6 to 2 carbon atoms, and an acyl group having λ to t carbon atoms. preferable.

Among the groups represented by X in the above general formula (1), oxygen atoms and sulfur atoms each having λ to 10 carbon atoms.

Preferred are alkylene groups and phenylene groups which may contain a benzene ring χ.

60 of the thermofusible substances represented by the above general formula (I)
Those having a melting point of 0.06 or higher are preferred.

Those having a melting point of %Vc700C to /IO'C are preferred.

Representative examples of the thermofusible substance represented by the above general formula (I) include the following compounds.

/, ≠-bis(2-hydroxy-≠-methoxybenzoyloxy)butane, /,? -bis(2-hydroxy-Hiro-methoxybenzoyloxy)octane, /, Hiro-bis(2-hydroxy-Hiro-methoxybenzoyloxymethyl)benzene, /.

≠-bis(2-hydroxy-≠-benzyloxybenzoyloxy)butane, /, 2-bis(2-hydroxy-
≠-benzyloxybenzoyloxy)ethane, /,!
-Bis(2-hydroxy-≠-benzyloxybenzoyloxy)-3-oxapentane, /,! -Bis(2-
Hydroxy-≠-benzyloxybenzoyloxy)-
3-Thiapentane, /, 3-bis(2-hydroxy-≠
-penzyloxybenzoyloxymethyl)benzene,
/, Hiro-bis(2-hydroxy-≠-β-phenoxyethoxybenzoyloxy)butane, /.

! -bis(2-hydroxy-≠-β-7dinoxyenoxyethoxybenzoyloxine, /, 4t-bis(2-
Hydroxy-≠-acetoxybenzoyloxy)butane, /, tA-bis(2-hydroxy-Hiro-benzoyloxybenzoyloxy)butane, i,r-bis(2-hydroxy-≠-benzoyloxybenzoyloxy)-
3-oxapentane, /, ≠-bis(2-hydroxy-
≠-methoxybenzoyloxy)benzene, /, Hiro-bis(2-hydroxy-Hiro-benzyloxybenzoyloxy)benzene, etc.

These may be used alone or with other thermofusible substances (e.g. % Kaisho A
o-sl, J'l#, JP-A-60-2/R-orz, etc.) may be used in combination.

The electron-donating colorless dye used in the present invention includes:

Triarylmethane compounds, diphenylmethane compounds, xanthine compounds, thiazine compounds, spiropyran compounds, etc. are used. To illustrate some of these, triarylmethane compounds include 3,3-bis(p-dimethylaminophenyl)-6-dimethylamino 7-thallide (i.e., crystal violet lactone);
3.3-bis(p-dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl)-3-(he3-
Dimethylindol-3-yl)phthalide, 3-(p-
Dimethylaminophenyl)-j-(2-methylindol-3-yl)7talide, etc., and diphenylmethane compounds include Hiroshi, ≠'-bis-dimethylaminobenzhydrin benzyl ether, and N-halophenyl-leucoauramine. , N-2, <4. j + -lichlorophenylleucoolamine, etc., and xanthine compounds include o-tamine-B-anilinolactam, rhodamine (p-nitroanilino)lactam, rhodamine B (
p-chloroanilino)lactam, 2-dibenzylamino-6-diethylaminofluorane, 2-anilino-6-
Diethylaminofluorane, 2-anilino-3-methyl-ot-diethylaminofluorane, 2-anilino-3-
Methyl-A-N-cyclohexyl-N-methylaminofluorane, 2-anilino-3-methyl-AN-ethyl-N-isoamylaminofluorane, 2-0-chloroanilino-ot-diethylaminofluorane, 2-m-
Chloroanilino-4-diethylaminofluorane 1,2
-(3,IA-dichloroanilino)-6-diethylaminofluorane, 2-octylamino-O-diethylaminofluorane, 2-dihexylamino-2-diethylaminofluorane, λ-m-trichloromethylanilino-
Otsu-diethylaminofluorane, 2-butylamino-3
-chloro-ot-diethylaminofluoran, 2-ethoxyethylamino-3-chloro-6-diethylaminofluoran, 2-anilino-3-chloro-6-diethylaminofluoran, 2-diphenylamino-ot-diethylaminofluoran, 2-anilino-3-methyl-6-siphenylaminofluorane.

2-anilino-3-methyl-yo-chloro-4--/ethylaminofluorane, 2-anilino-3-methyl-6-
Dinitylamino-7-methylfluorane, 2-anilino-3-methoxy6-sibutylaminofluorane, 2-〇-dichloroanilino-6-cyptylaminofluorane 2
-p-chloroanilino-3-ethoxy-6-diethylaminofluoran 1,2-phenyl-1+-') ethylaminofluoran, etc. Thiazine compounds include:
There are pensoyl leucomethylene blue, p-nitrobenzyl leucomethylene blue, etc., and spiro compounds include 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3゜3'-cyclorosespiro-dinaphthopyran, 3 -benzylspiro-cinna7topyran, 3-methyl-naphtho-(3-methoxy-benzo)
-spiropyran, j-propyl-spiro-dibenzopyran, etc. These may be used alone or in combination.

The electron-accepting compounds used in the present invention include monophenols, bisphenols, 1. Hydroxybenzoic acid esters, salicylic acid derivatives, metal salts thereof, and the like are used. Among these, the following general formulas (l[) to (
When the hydroxybenzoic acid ester represented by IV) is used, the stability of the colored image and the dusting of the colored area are improved.

(In the formula, R2 represents an alkyl group having 2 to 2 carbon atoms, and a cycloalkyl group.) Examples of some of these include monophenols, p-benzylphenol, p-benzyloxy Phenol, p-β-phenoxyethoxyphenol, Hiro-β-p-chlorophenoxyethoxyphenol, ≠-β-p-tolyloxyethoxyphenol, p-phenylphenol, Hiro-α-cumylresorcin, etc., and bisphenols. As 2.
λ-bis(!-hydroxyphenyl)propane, /, /
-bis(≠-hydroxyphenyl)cyclohexane, 1
．． 3-bis(α,α-dimethyl-p-hydroxybenzyl)benzene, bisphenolsulfone, bis(β-
p-hydroxyphenylthioethoxy)methane, etc., and as salicylic acid derivatives and metal salts thereof, 3. j-
bix-α-methylbenzylsalicylic acid, 3. J-bis-αα-dimethylbenzylsalicylic acid, 3°! -Bisnonylsalicylic acid, ≠- includes tadecylsalicylic acid and its zinc salt, aluminum salt, etc.Hydroxybenzoic acid esters include ≠-hydroxybenzoic acid butyl ester, ≠-hydroxybenzoic acid octyl ester, ≠-
Hydroxybenzoic acid cyclohexyl ester, Hiro-Hydroxybenzoic acid benzyl ester, ≠-hydroxybenzoic acid β-phenoxyethyl ester, ≠-hydroxybenzoic acid β-O-chlorophenoxyethyl ester, Hiro-
Hydroxybenzoic acid p-methylbenzyl ester, ≠-
Hydroxy7talic acid dimethyl ester, 2. ≠-dihydroxybenzoic acid propyl ester, 2. ≠-dihydroxybenzoic acid butyl ester, 2. ≠-dihydroxybenzoic acid cyclohexyl ester, co≠-dihydroxybenzoic acid benzyl ester, 2. ≠-dihydroxybenzoic acid p-methylbenzyl ester, Korg dihydroxybenzoic acid p-kurotobenzyl ester, 2. −≠−
Dihydroxybenzoic acid-β-phenoxyethyl ester, co,≠-dihydroxybenzoic acid-β-p-)lyloxyethylbenzyl ester, 2. ≠-dihydroxybenzoic acid-β-0-chlorophenyloxyethyl ester,
Examples include Korg dihydroxybenzoic acid β-phenylethyl ester.

The heat-sensitive recording material according to the present invention has sufficient color development sensitivity.

Moreover, the colored images are extremely stable and hardly change color or fade even after long-term light irradiation, heating, or humidification, which is particularly advantageous from the viewpoint of long-term preservation of records.Next, the heat-sensitive recording material according to the present invention The specific manufacturing method will be described.

The heat-sensitive recording material is produced by mixing a binder dissolved or dispersed in a solvent or dispersion medium with a sufficiently finely ground electron-donating colorless dye, an electron-accepting compound, and a thermofusible substance, and then adding kaolin and calcined kaolin. , talc, waxite,
Oil-absorbing pigments such as diatomaceous earth, calcium carbonate, aluminum hydroxide, magnesium hydroxide, magnesium carbonate, titanium oxide, barium carbonate, urea-formalin filler, and cellulose filler are added to form a coating liquid.

Add to this as necessary/11 rough-in wax emulsion, latex binder, sensitivity improver, metal soap, antioxidant, ultraviolet ray absorber, 1 image preservation improver, etc.
Can be added.

The coating solution is applied to a support such as paper, plastic sheet, or resin-coated paper and dried. When preparing a coating liquid, all the components may be mixed and pulverized at the same time from the beginning, or they may be combined in appropriate combinations, pulverized and dispersed separately, and then mixed.

In addition, the coating solution may be incorporated into the support. parts, 7 to 30 parts by weight of thermofusible substance, 0 to 75 parts by weight of pigment, 7 to 7 parts by weight of binder, and 20 to 20 parts by weight of dispersion medium (solvent). 30
It is 0 parts by weight.

One or more electron-donating colorless dyes may be used in combination. Water is most desirable as the dispersion medium (solvent).

Examples of binders used in the present invention include styrene-butadiene copolymers, alkyd resins, acrylamide copolymers, vinyl chloride-vinyl acetate copolymers, styrene-maleic anhydride copolymers, synthetic rubbers, and gum arabic.

Examples include polyvinyl alcohol and hydroxyethyl cellulose.

In particular, water-soluble binders such as gum arabic, polyvinyl alcohol, hydroxymethyl cellulose, and carboxymethyl cellulose are desirable in relation to the dispersion medium (solvent).

Examples of waxes include norahin wax, carnauba wax, microcrystalline wax, polyethylene wax, and higher fatty acid amides such as stearic acid amide, ethylene bisstearamide, and higher fatty acid esters.

Examples of metal soaps include higher fatty acid polyvalent metal salts such as zinc stearate, aluminum stearate, calcium stearate, and zinc oleate.

Examples of the image preservation improving agent include phenol or its derivatives in which at least 7 or more of the λ or 6 positions are substituted with an alkyl group, and among these, phenol or its derivatives in which at least 7 or more of the 2 or 6 positions are substituted with a branched alkyl group. Substituted phenols or derivatives thereof are preferred. Moreover, those having a plurality of phenol groups in the molecule are preferable, and those having 1 to 3 phenol groups are particularly preferable. Specific examples of these compounds include bis[3,3-bis-(Hiro'-hydroxy-3'-tart-butylphenyl)-
Butanoic acid coglycol ester, bis-[3
,3-bis-(Hiro'-hydroxy-J', l-diter
t-Butylphenyl)butanoic acidoglycol ester, bis-[3,3-bis-(2'-methyl-≠
'-Hydroxy, t'-tert-butylphenyl)
- Phtanoic acid] Glycolic acid, /,
/, 3-tris(2-methyl-≠-hydroxy-j-t
ert-butylphenyl)butane, ≠, Hiro'-thiobis(3-methyl-1,-tert-butiflephenol)
,≠,lA'-thiobis(2-methifure-tert
-butylphenol), 2,2'-thiobis(Hiro-methyl-A-tert-butylphenol).

2.2'-methylenebis(≠-methyl-A-tert-
butylphenol), 2,2'-methylenebis(Hiro-ethyl-1,-tert-butylphenol), Hiro, t
A'-phthyritin bis(3-methyl-6-tert-
butylphenol), Hiroshi, ψ′-methylenebis(,2,
A-di-tert-butylpheno-1).

λ-tert-butyl≠-tert-butoxyphenol, 2,2-dimethyl-≠-inpropyl-7-te
rt-butyl-6-glomanol, 2,2-dimethyl-
4-t-butyl-! -benzofuranol, g((4,+
-Bis(tertbutylthio)-5-trisulfate-2-
Examples include yl]amino]λ, tert-butylphenol, and the like.

The amount of these compounds used is J--, 200 weight percent, preferably 20 to io, based on the electron-accepting compound.
o″it percent.

Examples will be shown below, but the present invention is not limited only to these examples.

Example 1 - ≠ 2-anilino-3-methyl-, an electron-donating colorless dye
A-N-methyl-N-cyclohexylaminofluorane 3F and λ-anilino-3-chloro-6-diethyl-minofluorane 2F were dispersed in a ball mill overnight with an aqueous solution of tatipolyvinyl alcohol (carbon value tachi, polymerization degree 10Oθ). did. On the other hand, similarly, the electron-accepting compound loyw! shown in Table 1. % polyvinyl alcohol water-soluble fi100F in a ball mill overnight. Further, 10P of the thermofusible substance shown in Table 1 was dispersed in a ball mill with J'' Tivoli Vinyl Alcohol Aqueous Solution 10011 for a day and night, and after mixing these three types of dispersions, 20P'l of kaolin was added and well dispersed. , 4 Rough-in Wax Emulsion J-0% Dispersion (Middle East Fat Cellosol #≠2♂) was added to prepare a coating liquid.

The coating liquid was applied to neutral paper having a basis weight of 6,097 m'' so that the coating amount of solids was 7 m'', and the coated paper was dried with a TOOC for 7 minutes.

Heating coated paper by facsimile takes 3 energy! mJ
A black printed image was obtained by heating and coloring at /-. Macbeth Company RD-! The color density of the colored area was determined using the /l/- type.

The results are shown in the first IK.

Further, after the obtained color former was left in an atmosphere of ≠o'C1RH5'7% for 2 hours, the concentration of the color member was measured, and the residual rate of the color member was calculated using a linear equation. The results are shown in Table 1.

A similar test was conducted using the same formulation as Comparative Example/~Hiro Example/~μ except that only the heat-fusible substance was removed.

The results are also shown in Table 1.

From Table 1, it can be seen that the thermal recording paper of the present invention has a higher color density and less discoloration than the comparative thermal recording paper.

Claims (1)

[Scope of Claims] A thermosensitive recording characterized by containing (A) an electron-donating colorless dye, (B) an electron-accepting compound, and (C) a thermofusible substance represented by the following general formula (I). Materials▲Mathematical formulas, chemical formulas, tables, etc.▼(I) In the above formula, R represents an alkyl group, aryl group, or acyl group.
represents a divalent group.