JPS61280988A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material having sufficient developed color density and color forming sensitivity, by mixing an electron acceptive compound with a specific diether compound in a state dispersed so as to have an average particle size of 3mum or less. CONSTITUTION:An electron acceptive compound is mixed with a diether compound represented by general formula I (wherein Ar1 and Ar2 are a substituted or unsubstituted aryl group and n is a positive integer of 10 or less) in a state dispersed so as to have an average particle size of 3mum or less. As an embodiment of an electron donating leuco dye to be used, a triarylmethane compound, a diphenylmethane compound, a xanthene compound, a thiazine compound and a spiropyrane compound are used. As the embodiment of the electron acceptive compound, there are a phenolic compound, an org. acid or a metal salt thereof and oxybenzoate etc. and the phenolic compound is especially pref. because of the reduced use amount thereof and a bisphenol compound is especially pref.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to a heat-sensitive recording material E-1, and particularly to a heat-sensitive heat recording material with improved color development properties.

(Prior Art) Good and bad heat recording materials using an electron-donating colorless dye precursor and an electron-accepting compound are disclosed in Japanese Patent Publication No. 4Aj-/3032, Japanese Patent Publication No. 4C140, etc. The minimum performance that such a heat-sensitive recording material should have is (1) sufficient color density and color development sensitivity; ) The color forming body must have sufficient fastness after color development, etc., but currently there is no product that completely satisfies these requirements. )
Research is being carried out intensively.

The method and the melting point t- of the electron-accepting compound itself are
The temperature may be 60 to 100 °C. However, it is difficult to control the melting point of phenolic compounds, which are electron-accepting compounds that are currently widely used, and the tamienol compound itself is expensive and impractical.

Other methods include Tokko Sho Data No. 77741Ct and Tokko Sho! No. 147 describes the use of an organic acid, a phenolic compound, and gold together as an electron-accepting substance, and the use of a polyvalent metal salt of a compound having an alcoholic hydroxyl group. Tokuko Akij/--Tata 4/-! No. 1 describes the use of a copolymer of hydroxyethyl cellulose and maleic anhydride.

Kutoku Kosho! /-27! Tata issue L and Tokukai Shosan 1-/?
VC No. 131 describes the addition of waxes.

In addition, Tokukai Sho≠tar 3≠j Hiroλ, Tokukai Sho μtar/ /
jJ-144, JP-A-10-/41! ri No. 333,
Tokukai Akira! λ-7067≠≦ issue, JP-A-Sho J-J-1436
Issue, Tokukai Show 1! -11034, Tokukai Sho! 3-+ryz
thioacetanilide, phthalonitrile, acetamide, di-β-
Naphthyl-p-phenylenediamine, fatty acid amide, acetoacetanilide, diphenylamine, benzamide,
Nitrogen-containing organic ornaments such as Carbasol 1+ are 2.
It is described that thermofusible substances such as 3-di-m-tolylbutane, dimethylbiphenyl, and carboxylic acid esters such as dimethyl isophthalate, diphenyl phthalate, dimethyl terephthalate, etc. are added as sensitizers. has been done. Also, British Patent Publication -
071A,! ! ! No. 2 describes the addition of hindered phenols.

However, heat-sensitive recording materials produced using these methods are still unsatisfactory in terms of 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 is to provide a heat-sensitive recording material comprising an electron-donating colorless dye precursor and an electron-accepting compound dispersed on a support, in which the electron-accepting compound has the following general formula (1). This is achieved by a heat-sensitive recording material characterized in that it is mixed with a diether compound shown in ) and dispersed to have an average particle size of 3 μm or less.

Ar l-0-CnH2fl-o-Ar2
(1) In the above formula, Arl and Ar2 are substituted or unsubstituted aryl groups k, n #:t'' or less positive integer a
t represents.

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.

Some examples of these include, as triarylmethane compounds, 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (i.e., crystal violet lactone), 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (i.e., crystal violet lactone), -Dimethylaminophenyl supraphthalide,'-(D-dimethylaminophenyl)-3-(/,J-dimethylindol-J-yl)phthalide%J-(p-dimethylaminophenyl)-
J-(comethylindol-3-yl)phthalide, etc., and diphenylmethane compounds include Hiroshi, San'
-Bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl-leucoolamine, N-2,≠
, J-trichlorophenylleucoauramine, etc.
Examples of xanthine compounds include rhodamine-B-anilinolactam, rhodamine (p-nitroanilino)lactam, rhodamine B (p-chloroanilino)lactam, colabenzylamino-6-diethylaminofluoran,
λ-anilino-6-dinithylaminofluorane, co-anilino-3-methyl-6-dinithylaminofluorane,
2-anilino-J-methyl-6-cyclohexylmethylaminofluorasi, co-0-chloroanilino-6-dinithylaminofuran, co-m-chloroanilino-4-
Diethylaminofluorane, -1(3,dichloroanilino)-6-dinithylaminofluorane, -1octylamino-4-diethylaminofluorane, Kodihexylamino-6-diethylaminofluorane, 2-m-
1-70 methylanilino-6-diethylaminofluorane, 2-butylamino-3-chloro-6-diethylaminofluorane, λ-ethoxyethylamino-3-chloro-6-diethylaminofluorane, col-chloroanilino-3- Methyl-6-sibutylaminofluorane,
co-anilino 3-methyl-6-sioctylaminofluorane, λ-anilino 3-chloro-6-dinithylaminofluorane, 2-diphenylamino-haruka-diethylaminofluorane, λ-anilino 3-methyl-6-siphenylamino Fluorine, λ-phenyl-1-diethylaminofluorane, co-anilino 3-methyl-6-N
-Ethyl-N-isoamylaminofluorane, 2-anilino-3-methyl-j-chloro-6-diethylaminofluorane, 2-anilino-3-methyl-6-dinithylamino-7-methylfluorane, coanilino-3-methoxy- 6-cyptylaminofluorane, co-0-chloroanilino-6-cyptylaminofluoran, co-chloroanilino-3-ethoxy-6-N-ethyl-N-isoamylaminofluorane, 2-o-chloroanilino-
6-p-butylanilinofluorane, λ-anilino 3
-pentadecyl-6-diethylaminofluorane, coanilino 3-ethyl-6-cyptylaminofluorane, -monoanilino 3-ethyl-6-N-ethyl-N-isoamylaminofluorane, coanilino 3-methyl-4-N- Ethyl-N-γ-methoxypropylaminofluorane, coanilino-3-chloro-6-N-ethyl-N-isoamylaminofluorane, etc. Thiazine compounds include benzoylleucomethylene blue, p
-Nitrobenzylleucomethylene blue, etc., and spiro compounds include 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, J, J'
-cyclolosespiro-dinaphthopyran, 3-benzylspiro-dinaphthopyran, 3-methyl-naphtho-(3-
Examples include methoxybenzo) 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,
Among them, phenol compounds are particularly preferred because they can be used in small amounts, and among these, bisphenol compounds are preferred.

These compounds are disclosed in, for example, Japanese Patent Publication No. Sho μj-/lll32, Japanese Patent Publication No. Shoj/-co No. 2130, and the like. Specifically, Hiro-tertiary butyl phenol, $-722 phenol, hydroxydiphenoxide, α-
naphthol, β-naphthol, methyl-≠-hydroxybenzoate, 2, λ'-dihydroxybiphenyl,
J, J-bis(4cm hydroxyphenyl)furopane (
Bisphenol A), 4'-4''-isopropylidene bis(co-methylphenol), /,/-bis-(
3-chloro-4-11-hydroxy 7-ale) cyclohexane, /,/-bis-(3-chloro-hydroxyphenyl)-2-ethylbutane, 44.4c'-7-candalyimplylidene diphenol, cyclo-hydroxy Benzoic acid benzyl ester,
m-chlorobenzyl ester, hydroxybenzoic acid β-7enethyl ester, hydroxyl-21, pl
-dimethylphenylsulfone, /-t-butyl-≠-p
-Hydroxyphenylsulfonyloxybenzene, reference-
N-pendylufamoylphenol, 2. Hiro-dihydroxybenzoic acid p-methylbenzyl ester,
4C-dihydroxybenzoic acid-β-phenoxyethyl ester, 2. Examples include benzyl dihydroxy-6-methylbenzoic acid ester.

Among the diether compounds according to the present invention, the following general formula (f
Those represented by I[1,)i are preferred.

In the above formula, R1*Rz, Ra and R4 represent a hydrogen atom, an alkyl group having 6 or less carbon atoms, an alkoxy group or a halogen atom, n represents an integer from 2 to j, and R1, R2 and R3 R4 may combine with each other to form an aromatic ring.

In the above general formula ((I), R1=R2* R3 and R4 may be the same or different.

Examples of these diether compounds are shown below.

Some of the compounds are described in JP-A-Sho-s6art, and specific examples include the following compounds.

/, l-di(Hiro-methylphenoxy)butane mp, io ℃/, j-
Di(4A-methylphenoxy) is mp,! −2°CI
,! -di(≠=methylphenoxy)pronoξn mp, ta3°C1
, l-di(4cm isopropylphenoxy)butane mp. 7t'C/, J-
Diphenoxyethane mpo Ta100/-(≠-methylphenoxy) Cophenoxyethane mp, 100"C/-(
Hiro-chlorophenoxy) -2-phenoxyethane mp, 1O10C/-(
tert-butylphenoxy)-λ-phenoxyethane''mp, Pco・C/-(λ-chlorophenoxy) one-cophenoxyethane mp, 74'c/, 4C
-di(≠-chlorophenoxy)butane mp, / 04c0C
7-S7toxy(1)-2-phenoxyethane' mp, 104°C1,
μm diphenoxybutane mp, 7°C/- (see-
methylphenoxy) -2-(2-methylphenoxy)ethane mp, Ij0C/-(≠-
Methylphenoxy)-co(λ, 4cm dimethylphenoxy)ethane mp, 70℃/-($-
methylphenoxy) -J -(j-methylphenoxy(ethane mp, ta/"C
/-($-Fluorophenoxy) -2-phenoxyethane mp, Tao 'C/
-(3-methoxyphenoxy) monocophenoxyethane mp, 6°C/-
(derfluorophenoxy)-co(≠-methylphenoxy)ethane mp, iotoCl-(3
-methoxyphenoxy) -(methylphenoxy) ethane mp, 42°C/-(
4! -ethylphenoxy) -2-phenoxy mp, 106℃/-(≠
-ethoxyphenoxy) monocophenoxyethane mp, 723°CI-(
3-propylphenoxy) monocophenoxyethane mp, 4j'CI, J-
Di(4C-ethylphenoxy)intane mp, 13℃/-(4
A-hexylphenoxy) -cophenoxyethane ,, p, yr"c Among the diether compounds according to the present invention, to"c or more izo°
Those having a melting point of C or lower are preferred, and more preferably 70
Melting point between °C and above lλo 'C below 1! - is particularly preferred.

The electron-donating colorless dye precursor and electron-accepting compound of the present invention are each separately dispersed together with a water-soluble polymer using a ball mill, sand mill, attritor, three-roller mill, pebble mill, or the like. The diether compound of the present invention may also be added in a dispersed manner, or an electron-donating colorless dye precursor or
Although it is possible to use it by dispersing it simultaneously with an electron-accepting compound, it is essential to disperse it simultaneously with an electron-accepting compound in order to obtain a heat-sensitive recording material with high color density and high sensitivity, which is the objective of the present invention. It is. That is, when the diether compound is dispersed alone, the color development sensitivity is insufficient, and when it is dispersed simultaneously with the electron-donating colorless dye precursor, the sensitivity is similarly insufficient, and the color development sensitivity is insufficient. It has been found that it has the disadvantage that it tends to produce turnip+7t- when trying to obtain it.

The diether compound of the present invention is preferably dispersed simultaneously with the electron-accepting compound. In addition, it has good dispersibility, sufficient sensitivity, and little fog. This effect is further manifested by eutecticizing the electron-accepting compound and the diether compound in advance. Ninth, there is almost no difference from the melted product, and processes such as eutectic melting are unnecessary, which is preferable.

Furthermore, mixed dispersions have the advantage that they are less likely to cause fog than eutectic ones.

The mixing ratio of the diether compound and the electron-accepting compound of the present invention is 1:j to 3:l by weight.

Even better! fi/: J φ and Koni l.

If the proportion of the diether compound is smaller than this range, the effect of increasing sensitivity will be small; if it is too large, it will be difficult to obtain a saturated concentration and the storage stability of the color former will be reduced.

The electron-donating colorless dye precursor is preferably used in a ratio of 1:IO to 2:1, and more preferably in a ratio of /:IO to 1:1, with respect to the electron-accepting compound.

The dispersed electron-donating colorless dye precursor and the mixture of electron-accepting compound and diether compound are mixed in the above-mentioned ratio, and additives may be added to meet various requirements.

Examples of additives include dispersing oil-absorbing substances such as inorganic pigments in the binder in order to prevent the recording head from getting dirty during recording, and also as additives to improve the releasability of the head. Fatty acids, metal soaps, 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, pigments such as kaolin, calcined kaolin, talc, waxite, diatomaceous earth, calcium carbonate, aluminum hydroxide, magnesium hydroxide, magnesium carbonate, titanium oxide, barium carbonate, urea-formalin filler, and cellulose filler Examples of the waxes selected from among the above include paraffin wax, couch parrot wax 4, microcrystalline wax, polyethylene wax, and higher fatty acid esters.

Examples of the metal soap include polyvalent metal salts of higher fatty acids, ie, zinc stearate, aluminum stearate, calcium stearate, zinc oleate, and the like.

Binders used during dispersion include polyvinyl alcohol, droxyethyl cellulose, hydroxypropyl cellulose, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, and isobutylene-maleic anhydride copolymer.
Maleic anhydride copolymer, polyacrylic acid, polyacrylic acid amide, starch derivatives, casein, gelatin, carboxymethylcellulose, methylcellulose, etc.
1'I'm happy.

During dispersion, dispersibility is often improved by adding a small amount of surfactant or water-soluble oligomer.

In order to impart water resistance to these binders, water-resisting agents (gelling agents, cross-linking agents) may be added, or emulsions of hydrophobic polymers, specifically styrene-butadiene rubber latex, acrylic resin emulsions, etc. You can also add

Coating fluids are most commonly applied onto base paper, preferably neutral paper.

Generally, the coating amount is 2 to 1 ot7vt'' in terms of solid content, and the lower limit is determined by the density at the time of color development by heating, and the upper limit is determined mainly by economic constraints.

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

Example (1) Preparation of samples l to t Co-anilino 3-chloro-t-diethylaminofluorane 2° which is an electron-donating colorless dye precursor! f and co-anilino 3-methyl-A-N-methyl-N-cyclohexylaminofluorane λ, jf and kj% polyvinyl alcohol (ken measurement touch, degree of polymerization 1ooo) aqueous solution ro
A friend who spent two days and nights in a ball mill with T. On the other hand, bisphenol Aioy, which is also an electron-accepting compound, and
The diether compounds shown in the table and the sensitivity improver l0f1 conventionally used in heat-sensitive recording materials! -Disperse overnight in a hole mill with 100 ml of a 1% polyvinyl alcohol aqueous solution.

After mixing these dispersions of J@, kaolin (Jossia kaolin) was added to disperse well, and then No9 rough-in wax emulsion 30% dispersion (Chukyo Yushi Hydrin P-7) and zinc stearate were added. Emulsion 30% dispersion (Chukyo Yushi Hydrin Z-7) T-21 each added, coating liquid and L79.

Coating liquid FijO9/rIL was coated on neutral paper with a basis weight of 6f/m2 as a solid content coating amount, and after drying at O'C for 1 minute, it was coated with a snow coater at a linear pressure of 60W/cIL. Render and coated paper.

(2) Preparation of sample tar 1 Samples with large dispersed particle sizes were prepared by setting the dispersion time of the mixture dispersion of an electron-accepting compound and a diether compound to 3 hours, 4 hours, and 1 hour. , sample/-r
Create coated paper in the same manner as Lfc.

(3) Preparation of Sample 12 Coanilino 3-chloro-6-dinithylaminofluorane 2. jf and 1,2-difeno sietan! ft-
Then, the mixture was dispersed in a ball mill for two days and nights with 'fk polyvinyl alcohol aqueous solution toy to obtain a dispersion having an average particle diameter of i and 4 ct μm. Similarly, 2-anilino-3-methyl-A-N-
Methyl-N-cyclohexylaminofluorane λ, jt
and/or Kodiphenoxyethane jft to obtain a dispersion having an average particle size of 2.31 μm. Bisphenol Al0
ff! - Dispersion was carried out overnight in a ball mill with polyvinyl alcohol aqueous solution 1009. After mixing these three types of dispersions, coated paper was prepared in the same manner as samples 1 to 1.

(4) Preparation of Samples 73-/j In Samples 1-3, the bisphenol and the diether compound were not dispersed simultaneously, but were used separately dispersed together with the j% polyvinyl alcohol aqueous solution jOf.

(5) Coated paper is evaluated as follows9.

(1) ° Printing sensitivity Using a Kyocera test tester, the printing energy t-Jjm
J/sn*, print solid black, and measure the density with a Macbeth densitometer. Print density is jr do
t/n+X 4 d o t/its pulse width/ml.

((I) Fog The fog of the coated paper was measured with a Macbeth densitometer, and then stored in an atmosphere of to 0cJ01RH for 2 hours to determine thermal fog, and the fog was determined in the same manner.

The results are shown in the table below. The dispersed particle size shown in Table 1 indicates the volume average particle size, and was determined using a particle size distribution analyzer (Microtrac) manufactured by LAN.

Claims (1)

[Scope of Claims] A heat-sensitive recording material prepared by coating an electron-donating colorless dye precursor and an electron-accepting compound on a support, wherein the electron-accepting compound is a diether compound represented by the following general formula (I). A heat-sensitive recording material characterized in that it is mixed and dispersed to have an average particle size of 3 μm or less. Ar_1-O-C_nH_2_n-O-Ar_2( I
) In the above formula, Ar_1 and Ar_2 represent substituted or unsubstituted aryl groups, and n represents a positive integer of 10 or less.