JPS61283592A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain sufficient developed color density and color forming sensitivity as well as favorable preservation stability and matching property for a thermal head, by incorporating an electron-donative colorless dye, an electron- acceptive compound and an alkyldicarboxylic acid ester derivative. CONSTITUTION:The alkyldicarboxylic acid ester derivative is a compound of formula I, wherein Ar is subst. or unsubst. phenyl or naphthyl, and each of R and W is a 1-6C bivalent group, and preferably has a melting point of 50-150 deg.C. The weight ratio of the amount of the electron-donative colorless dye to the amount of the electron-acceptive compound is preferably 1:5-2:3. The ester derivative is used in an amount of 20-300wt% based on the amount of the electron-acceptive compound, whereby a sufficient sensitivity-enhancing effect can be obtained.

Description

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

<Prior art> Heat-sensitive recording materials using electron-donating colorless dyes and electron-accepting compounds are disclosed in Japanese Patent Publication No. 4cj-111032 and Japanese Patent Publication No. 4cj-111032.
3-4!140 etc. The minimum performance that such a heat-sensitive recording material should have is (1) sufficient color density and color development sensitivity, (2) no occurrence of capri (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.

One way to do this is to adjust the melting point of the electron-accepting compound itself to 6-1-too"c. However, the melting point of phenolic compounds, which are electron-accepting compounds that are currently widely used, can be adjusted. It is difficult to do so, and the phenolic compound itself is expensive and impractical.

Other methods include Tokko Sho≠2-/7711t and Tokko Sho! /-32. No. t67 describes the combined use of an organic acid and a phenolic compound as an electron-accepting substance, or the use of a polyvalent metal salt of a compound having an alcoholic hydroxyl group. Tokko Akira again! Nokotsuta 4t No. 3 describes the use of a copolymer of droxyethyl cellulose and maleic anhydride.

tTh special public Akira! No. l-27199 and % Kai Akihiro r-i
tco No. 37 includes six articles about adding waxes.

In addition, Tokukai Sho Getter 3 μl Da No. 1, Tokukai Sho≠ri-//!
! -1≠ issue, Tokukai Sho! 0-/≠? JjJ issue, Tokukai Sho! Ko 1067≠No. 6, Tokukai Sho 13-jbu 3 No., Toku Kai Sho!
Thioacetanilide,
Phthalonitrile, acetamide, di-β-naphthyl-p
- Nitrogen-containing organic compounds such as phenylenediamine, fatty acid amide, acetoacetanilide, diphenylamine, benzamide, carbazole, etc.
- Addition of thermofusible substances such as tolylbutane, p,p'-dimethylvinyl, or carboxylic acid esters such as dimethyl isophthalate, diphenyl phthalate, dimethyl terephthalate, etc., as a sensitizer is described. There is. Also, British Patent Publication No. 2,07μ, JJ
No. jA describes the addition of hindered phenols.

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

In order to solve this problem, the present inventors have investigated thermofusible substances with high color development sensitivity, such as naphthoic acid derivatives, diphenoxyalkane derivatives, and phenoxyalkylcarboxylic acid phenyl ester derivatives, but these compounds And heat-sensitive recording materials containing these have drawbacks such as sublimation, insufficient storage stability, poor matching with thermal heads, and poor compound stability. was.

<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 characterized by containing an electron-donating colorless dye, an electron-accepting compound, and an alkyl dicarboxylic acid ester derivative.

Among the alkyldicarboxylic acid ester derivatives according to the present invention, those represented by the following general formula (I) are (I) where Ar is a substituted 1+ unsubstituted phenyl group or a naphthyl group, and R and W are carbon atoms. Represents a divalent group having 7 to t atoms.

Among the alkyl dicarboxylic acid ester derivatives represented by the above general formula (I), those represented by the following general formula (It) are particularly preferred (I) In the above formula, X and Y may be the same or different and a hydrogen atom, Lower alkyl group, lower alkoxy group, halogen atom, anru group, aryl group, cyclohexyl group or cyclohexenyl group, R is a covalent group having from 1 to 6 carbon atoms, and W is 2 to 2 carbon atoms. Represents a valence group. Moreover, X and Y may be connected to form a naphthalene ring.

Among the above alkyl dicarboxylic acid ester derivatives,
Those with a melting point of °C-/10°C are preferred, especially jO°C~/! Those having a melting point of 0°C are preferred.

The heat-sensitive recording material containing the alkyl dicarboxylic acid ester derivative according to the present invention has sufficient color density and color development sensitivity, and also has little decrease in color development sensitivity over time and fog, and has sufficient fastness of the color image after color development. Furthermore, the mating properties with the thermal head are good, and there are no problems such as adhesion of debris or scratches.

Next, specific examples of the alkyl dicarboxylic acid ester derivatives according to the present invention will be shown, but the present invention is not limited thereto.

/)/, J-bis(β-phenoxyethoxycarbonyl)ethane J)/, J-bis(β-p-methylphenoxyethoxycarbonyl)ethane-t)'sλ-bis(β-p-chlorophenoxyethoxycarbonyl) ethane)/, J-bis(r-phenoxypropyloxycarbonyl)ethanez)i,a-bis(β-p-methoxyphenoxyethoxycarbonyl)ethane6)bis(β-phenoxyethoxycarbonyl)methane7)/, J-bis(β-phenoxyethoxycarbonyl)ethylene/2-bis(β-m-methylphenoxyethoxycarbonyl)ethylene? ) 7.2-Bis(β-1-dimethylphenoxyethoxycarbonyl)ethylene IO) 19.2-Bis(β-0-methylphenoxyethoxycarbonyl)ethylene//)/, ≠-bis(β -phenoxyethoxycarboel)butane/J)/, Hiro-bis(β-p-methylphenoxyethoxycarbonyl)butane/J)/, 4A-bis(β-p-chlorophenoxyethoxycarbonyl)butane/4')/ , 4-his(β-phenoxyethoxycarbonyl)hexane, etc.

Examples of the electron-donating colorless dye used in the present invention include 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)-1-dimethylaminophthalide (i.e., crystal violet lactone);
3.3-Bis(p-dimethylaminophenyl)phthalide%J(El-dimethylaminophenyl)-J-(/,J
-dimethylindol-3-yl)phthalide, J(p-
dimethylaminophenyl)-J-(nomethylindol-3-yl)phthalide, etc., and diphenylmethane compounds include !, 4C'-bis-dimethylaminobenzhydrin benzyl ether, and N-halophenylleucoolae. There are min, N-co, da,!-trichlorophenyl leuco auramine, etc., and examples of the xyf7-based compounds include rhodamine-B-anilinolactam, rhodamine (p-nitroanilino)lactam, and rhodamine B (p-chloroanilino). ) lactam, co-dibenzylamino-t-diethylaminofluorane/, λ-anilino-1-diethylaminofluorane, no-anilino-3-methyl-6-dinithylaminofluorane, no-anilino-3-methyl-t-cyclohexylmethylaminofluorane, no-0 -chloroanilino-6-dinithylaminofluoran 7b2-m-chloroanilino-t-diethylaminofluorane, J-(J,≠-dichloroanilino)-A-
Diethylaminofluorane, noanilino-3-methyl-j-N-ethyl-N-tetrahydrofurfurylaminofluorane, noanilino-3-methyl-j-N-butyl-N-tetrahydrofurfurylaminofluorane, noanilino-3- Methyl-4-N-ethyl-N-imbutylaminofluorane, -octylamino-4-diethylaminofluorane, -1-dihexylamino-6-ethylaminofluorane, λ-m-1 lifluoromethylanilino Bu-diethylaminofluoran, coptylamino-3-chloro-4-diethylaminofluoran, λ
-ethoxyethylamino-3-chloro-bu-diethylaminofluorane, J-p-chloroanilino-3-methyl-t-dibutylaminofluorane, noanilino-3-
Methyl-6-cyoctylaminofluorane, noanilino-3-chloro-4-diethylaminofluorane, J-
Diphenylamino-t-diethylaminofluorane, no-anilino-3-methyl-4-diphenylaminofluorane, no-pheny-4-diethylaminofluorane,
No-anilino-3-methyl-4-N-ethyl-N-isoamylaminofluorane, λ-anilino-3-methyl-! -Chloro-4-diethylaminofluorane, no-anilino-3-methyl-t-diethylamino-7-methylfluoran, λ-anilino-3-methoxy-6-cyptylaminofluorane, no-0-chloroanilino-t-dibutylamino Fluoran%λ-p-chloroanilino-3-
Ethoxy-4-N-ethyl-N-isoamylaminofluorane, no-0-chloroanilino J-p-butylanilinofluorane, co-anilino 3-is phtadecyl-t
-diethylaminofluorane, co-anilino 3-ethyl-4-cyphthylaminofluorane, co-anilino 3-ethyl-AN-ethyl-N-isoamylaminofluorane, -1-anilino 3-methyl-4-N-ethyl-N-γ -Methoxypropylaminofluorane, λ-anilino-3-chloro-4-N-ethyl-N-ynamylaminofluorane, etc. Thiazine-based compounds include tea,
Examples of spiro compounds include benzoyl leucomethylene blue, p-nitrobenzyl leucomethylene blue, and 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, J,! '-Cyclolosespirosinaphthopyran, 3-benzylspirosina7
Topyran, 3-methyl-naphtho-(3-methoxy-benzo)spiropyran, 3-propyl-spiro-dibenzopyran, and the like. These may be used alone or in combination.

Examples of electron-accepting compounds include phenolic compounds,
Organic acids or their metal salts, oxybenzoic acid esters,
Phenol compounds, in particular, are preferably used because they require only a small amount;
It is well described in the OJ Ri-go issue, the special public Shojl-Kota IJO issue, etc. Specific Niha, Hiro-tertiary butylphenol, μ-phenylphenol, l-hydroxydiphenoxide, α-naphthol, β-naphthol, methyl-
p-hydroxybenzoate, -9λ'-dihydroxybiphenyl, co, corbis(μm hydroxyphenyl)furopane (bisphenol A), Hiroshi, 3'-inpropylidene bis(comethylphenol), I, /-bis-(3- Chloro-μm hydroxyphenyl) hexane, i,i-bis-(3-chloro-hydroxyphenyl)-coethylbutane, 'I g 4''-secondary isbuteridenediphenol, μm benzyl hydroxybenzoate ester, dihydroxybenzoic acid-m-chlorobenzyl ester, ≠-hydroxybenzoic acid β-phenethyl ester, Hiro-hydroxy-λ′, ≠′-dimethyldiphenylsulfone, bis(β-≠-hydroxyphenylthioethoxy J methane, l, 3-bis-(≠-hydroxyphenylthio]---hydroxypropane, /
-('<4-hydroxyphenyl)-/-(J-β-proynyl-μmhydroxyphenyl)cyclohexanenot-t-butyl-11-p-hydroxyphenylsulfonyloxybenzene, ≠-N<ndylsulfamoylphenol, , ≠-dihydroxybenzoic acid-p-methylbenzyl ester, J,4A-dihydroxybenzoic acid-β-phenoxyethyl ester, J,4t-dihydroxy-4-methylbenzoic acid benzyl ester, and the like.

The alkyl dicarboxylic acid ester derivative used in the present invention is used after being dispersed in a dispersion medium to a particle size of 10 μm or less using a ball mill or the like. Alternatively, the electron-donating colorless dye and/or the electron-accepting compound may be added at the same time as being dispersed in the dispersion medium using a ball mill or the like.

The electron-donating colorless dye and electron-accepting compound used in the present invention are pulverized and dispersed in a dispersion medium to a particle size of ioμ or less, preferably 3μ or less. As the dispersion medium, a water-soluble polymer aqueous solution having a concentration of about 1/0% is generally used, and dispersion is carried out using a ball mill, sand mill, attritor, colloid mill, etc.

The ratio of the electron-donating colorless dye to the electron-accepting compound used is preferably between 1:1O and 1:1 by weight, and even /:! The alkyl dicarboxylic acid ester derivative is added in a weight ratio of 20% to 300%, particularly preferably ≠θ% to izo%, with respect to the electron-accepting compound.

If the amount of this alkyl dicarboxylic acid ester derivative added is too small, the sensitivity improvement effect aimed at by the present invention will not be sufficient, and if it is added in an amount of 300% or more, the heat capacity of the system will increase too much, which may cause problems. This leads to a decrease in sensitivity.

Additives are further added to the heat-sensitive coating liquid thus obtained in order to meet various requirements.

Examples of additives include round K to prevent the recording head from getting dirty during recording, oil-absorbing substances such as inorganic pigments dispersed in the binder, and fatty acids to improve the releasability of the head. , metal stones, etc. are added. Therefore, in general, in addition to a color forming agent and a color developer that directly contribute to color development, a pigment wax, additives, etc. are coated on a support to form a heat-sensitive recording material.

Specifically, kaolin as a pigment, calcined kaolin, talc, waxite, diatomaceous earth, calcium carbonate, aluminum hydroxide, magnesium hydroxide, magnesium carbonate,
Titanium oxide, barium carbonate.

The waxes selected from urea-formalin fillers, cellulose fillers, etc. include paraffin wax, cownaparous wax, microcrystalline wax, polyethylene wax, and higher fatty acid esters.

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

These are dispersed and applied in a binder.

Water-soluble binders are generally used, such as polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, and imbutylene-maleic anhydride copolymer. , polyacrylic acid, polyacrylic acid amide, starch derivatives, casein, gelatin, etc. In addition, water-resistant agents (gelling agents, cross-linking agents) are added to these binders for the purpose of imparting water resistance, and emulsions of hydrophobic polymers, specifically styrene-butadiene rubber latex, acrylic resin emulsions, etc. You can also add

The coating fluid is most commonly applied onto base paper, preferably neutral paper.

In general, the coating amount is λ~1011/m'' as a solid content.
”, and the lower limit depends on the density during heating color development.
The upper limit is determined primarily by economic constraints.

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

Example (1) Preparation of sample/-7 Co-anilino 3-chloro- which is an electron-donating colorless dye
Ni-diethylaminofluoran λ, Ji9 and λ-anilino-3-methyl-4-N-x f Ru-ni-N-amylaminofluoran 1. ! fi and 1% polyvinyl alcohol (saponification degree 22%, polymerization degree 1000) aqueous solution RO
The mixture was dispersed in a ball mill with g for a day and night. On the other hand, j% of bisphenol A109, which is also an electron-accepting compound,
Dispersion was carried out overnight in a ball mill with polyvinyl alcohol aqueous solution ioog. Further, as shown in Table 1, the alkyl dicarboxylic acid ester derivative 10fif and a 1% polyvinyl alcohol aqueous solution were dispersed in a ball mill for a day and night, and after mixing these dispersions, kaolin (Jossia Kaolin Coco OI) was added to disperse well. Then, 10% paraffin wax emulsion dispersion (Chukyo Yushi Cello Seal Na Sanko R) pg was added to prepare a coating liquid.

The coating liquid was applied onto neutral paper having a basis weight of 09/@2 so that the solid content coating amount was 49/rn''.
After drying at oC for 7 minutes, a coated paper was obtained by applying a super calender with linear pressure TOY4 sand.

Heating energy 3, rmJ by application ah facsimile
/mm'' to determine the color density.

The results are shown in Table 7.

(2) Creation of comparative sample With the exact same recipe as that used to create sample/-j,
A similar test was conducted using stearamide instead of the alkyl dicarboxylic acid ester derivative.

The results are also shown in Table 7.

It can be seen from Table 1 that the recording material according to the invention clearly has a high sensitivity.

Table 1 Patent Applicant Fuji Photo Film Co., Ltd. Procedural Amendment (7)
Showa era year month ≠ day

Claims (1)

[Claims] A heat-sensitive recording material comprising an electron-donating colorless dye, an electron-accepting compound, and an alkyl dicarboxylic acid ester derivative.