JPS627588A - Thermal recording material - Google Patents

Abstract

PURPOSE:To make color forming property favoarable, by using a leuco dye, a color developer and a specified auxiliary component in combination. CONSTITUTION:The thermal recording material utilizes a color forming reaction of a leuco dye with a color developer, and a diether compound of formula [I] is used jointly as an auxiliary component. The auxiliary component has high capability of dissolving the color developer (electron-acceptive compound) and the leuco dye (electron-donative colorless dye) when beging heated, and by controlling the melting point thereof it is possible to obtain a thermal recording material having an arbitrary sensitivity. In the formula, R1 is a bivalent organic group of formula II or III, wherein each of R2 and R3 is lower alkylene, Ar is subst. or unsubst. arylene and each of R4 and R5 is hydrogen, lower alkylene or subst. or unsubst. aryl, at least one of R4 and R5 being aryl, and each of X and Y is lower alkyl, halogen, alkoxy, aryl or aralkyl.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat-sensitive recording material, and particularly to a heat-sensitive recording material with excellent color development.

[Prior art]

General heat-sensitive recording materials are coated on a support such as paper or film, and contain a colorless or light-colored dye such as a leuco dye as a color former, and a phenolic compound (particularly bisphenol A) as a color developer to make the color develop when heated. A heat-sensitive color-forming layer in which a binder, filler, sensitivity improver, lubricant, and other auxiliary agents are further dispersed in a color-forming system consisting of an acidic substance such as an organic acid. Kosho 45-14
No. 039 and Japanese Patent Application Laid-Open No. 48-27736, it has been widely put into practical use. This type of thermal recording sheet produces a colored image through an instantaneous chemical reaction between a coloring agent and a color developer during heating (a thermal printer or facsimile machine with a built-in thermal head is used for heating). because there is,
Compared to other recording materials, records can be obtained in a short time using relatively simple equipment without complicated processing such as development and fixing, there is less noise generation and environmental pollution, and the cost is low. Due to its advantages, it can be used for copying books, documents, etc.

It is useful as a recording material for various information and measuring instruments such as electronic computers, facsimiles, telex machines, and medical measuring instruments.

On the other hand, in recent years, along with the development of society, there has been an increasing demand for higher speed and higher density recording. For this reason, there is a strong desire not only to increase the speed of the recording apparatus itself, but also to develop recording materials that can handle this. The first method is to lower the melting point of the electron-accepting compound used as the color developer to a practically acceptable level (e.g., 80 to 120°C) and lower the melting point with the leuco dye. The objective is to reduce the speed and speed up the process. However, it is difficult to control the melting point of phenolic compounds, which are color developers that are currently widely used in the field of heat-sensitive recording materials, and the phenolic compounds themselves are expensive, making them impractical. As method 2, for example, as described in JP-A-53-39139, JP-A-53-26139, JP-A-53-5636, JP-A-53-11036, etc.
Various waxes, fatty acid amides, alkylated biphenyls, substituted biphenylalkanes, coumarins,
There is a method of adding a low melting point heat-melting substance such as diphenylamines as a sensitizer (or melting point depressant). However, it cannot be said that the heat-sensitive recording materials produced based on these methods are still sufficient in terms of color density, color sensitivity, background whiteness, etc.

〔the purpose〕

The objects of the present invention are to have a single color density, sufficient color development sensitivity, suitable for high-speed recording, and high background whiteness.

It is an object of the present invention to provide a heat-sensitive recording material with extremely high practicality.

〔composition〕

The heat-sensitive recording material of the present invention is characterized in that it uses a diether compound represented by the following general formula (1) as an auxiliary component in a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and a color developer.

In the above formula, R1 is a divalent organic group represented by the general formula R2Ar R3-(II) or the general formula. In this case, the R2
, R3 represents a lower alkylene group, and Ar represents a substituted or unsubstituted arylene group, where the arylene group includes divalent aromatic groups such as a phenylene group and a naphthylene group. SR4%R represents a hydrogen atom, a lower alkylene group, or a substituted or unsubstituted aryl group, at least one of which is a substituted or unsubstituted aryl group, and ■ and n are O or a positive integer (usually , θ~6
), where the aryl group includes monovalent aromatic groups such as phenyl group, tolyl group, xylyl group, bibuenyl group, and naphthyl group. Note that the substituents that can be bonded to the arylene group and the aryl group include halogen atoms, alkoxy groups, and the like. X and Y are lower alkyl groups,
It represents a halogen atom, an alkoxy group, an aryl group or an aralkyl group, which may be the same or different, and k and Q represent an integer of 0 to 5.

The diether compound represented by the general formula (1) used in combination as an auxiliary component in the present invention is a phenolic compound that is a widely used color developer (electron-accepting compound) and a leuco dye (electron-donating colorless dye). ) has a high ability to dissolve when heated, and by adjusting the melting point of the diester compound used in combination, a heat-sensitive recording material with any sensitivity can be obtained.

The diether compound used in the present invention preferably has a melting point of 40 to 150°C, particularly preferably 50 to 120°C, from the viewpoint of storage stability and sensitivity as a heat-sensitive recording material. For example,
The present invention is not limited to these.

^ To ^ 6 Co c++
ψ B - The leuco dyes used in the present invention may be applied singly or in combination of two or more types, and as such leuco dyes, those applied to this type of heat-sensitive material may be arbitrarily applied.1 For example, triphenylmethane type, fluorane type, phenothiazine type,
Leuco compounds of dyes such as auramine and spiropyran are preferably used. Specific examples of such leuco dyes include those shown below.

3.3-bis(p-dimethylaminophenyl)-phthalide, 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone).

3.3-bis(p-dimethylaminophenyl)-6-dibutylaminophenyl, 3.3-bis(p-dimethylaminophenyl)-6-chlorophthalide.

3.3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3
-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane.

3-diethylamino-7,8-benzfluorane, 3-
Diethylamino-6-methyl-7-chlorofluorane, 3-(N-p-tolyl-N-dithylamino)-6-methyl-7-anilinofluorane.

3-pyrrolidino-6-methyl-7-anilinofluorane, 2-(N-(3'-trifluoromethylphenyl)
amino)-6-dinithylaminofluorane, 2-(3
, 6-bis(diethylamino)-9-(o-chloroanilino)xantylbenzoic acid lactam), 3-diethylamino-6-methyl-7-(m-trichloromethylanilino)fluoran, 3-diethylamino-7-(o- chloroanilino)fluoran, 3-dibutylamino-7-(0-chloroanilino)fluoran, 3-N-methyl-N-amylamino-6-methyl-7-
Aniritufluoran.

3-N-methyl-N-cyclohexylamino-6-methyl-77anilinofluorane, 3-diethylamino-6-methyl-7-7nilinofluorane, 3-(N,N-diethylamino)-5-methyl-7 −(
N.

N-dibenzylamino)fluoran.

Benzoylleucomethylene blue, 6'-ri♂low8'-methoxybenzoindolino-pyrylospirane.

6'-Bromo-3'-methoxy-benzoindolino-virirosvirane.

3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl)phthalide, 3-(2'-hydroxy-4'-dimethylaminophenyl)-3- (2'-Methoxy-5'-nitrophenyl)phthalide, 3-(2'-hydroxy-4'-diethylaminophenyl)-3-(2'-methoxy-5'-methylphenyl)phthalide, 3-(2'-methoxy-4'-dimethylaminophenyl)-3-(2'-hydroxy-4'-chloro-5'
-methylphenyl)phthalide, 3-morpholino-7-(N-propyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7-( N-benzyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluorane.

3-diethylamino-5-chloro-7-(α-phenylethylamino)fluoran, 3-(N-ethyl-P-toluidino)-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-(0 -methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-piperidinofluorane, 2-
Chloro-3-(N-methyltoluidino)-7-(p-n
-butylanilino)fluoran, 3-(N-benzyl-N-cyclohexylamino)-5
, 6-penzo 7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino 4
',5'-benzofluorane etc.

As the color developer used in the present invention, various electron-accepting compounds 1 such as phenolic compounds, thiophenolic compounds, thiourea derivatives, etc. are preferably used, and specific examples thereof are shown below.

4.4'-Isopropylidene bisphenol.

4.4'-isopropylidene bis(0-methylphenol).

4.4'-Secondary-butylidene bisphenol 4
．． 4'-isopropylidene bis(2-tert-butylphenol), 4.4'-cyclohexylidene diphenol, 4.4'
-isopropylidene bis(2-chlorophenol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol).

2.2'-methylenebis(4-ethyl-6-tert-butylphenol).

4.4'-Butylidenebis(6-tert-butyl-2methyl)phenol.

4.4'-thiobis(6-tert-butyl-2-methyl)phenol, 4.4'-diphenolsulfone, 4.4'-diphenolsulfoxide, isopropyl P-hydroxybenzoate, benzyl P-hydroxybenzoate , benzyl protocatechuate, stearyl gallate, lauryl gallate, octyl gallate, N,N'-diphenylthiourea, N,N'-di(■-chlorophenyl)thiourea.

Salicylanilide.

5-chloro-salicylanilide, salicyl-〇-chloroanilide, 2-hydroxy-3-naphthoic acid, 2-hydroxy-1-naphthoic acid, l-hydroxy-2-naphthoic acid, 1,7-di(4-hydroxy phenylthio)-3,5-
Dioxahebutane, 1,5-di(4-hydroxyphenylthio)-3-oxaheptane, metal salts of hydroxynaphthoic acid such as zinc, aluminum, calcium, etc.

In the present invention, in order to bind and support the leuco dye, color developer and auxiliary components on the support, various conventional binders can be used as appropriate, such as polyvinyl alcohol, starch and its derivatives, methoxy Cellulose derivatives such as cellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic amide/acrylic ester copolymer, acrylic amide/acrylic ester/methacrylic acid ternary copolymer , styrene/maleic anhydride copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, and other water-soluble polymers, as well as polyvinyl acetate, polyurethane, styrene/butadiene. Copolymer, polyacrylic acid, polyacrylic acid ester, vinyl chloride/
Latexes such as vinyl acetate copolymer, polybutyl methacrylate, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer, etc. can be used.

In addition, in the present invention, in addition to the leuco dye, color developer, and auxiliary components, if necessary, auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers, surfactants, thermofusible A sexual substance (or lubricant), etc. can be used in combination. In this case, examples of the filler include calcium carbonate and silica.

In addition to inorganic fine powders such as zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and surface-treated calcium and silica, urea-formalin resin, styrene/methacrylic acid copolymer, Examples include organic fine powder such as polystyrene resin.

The heat-sensitive recording material of the present invention can be produced, for example, by applying a coating solution for forming a heat-sensitive layer containing the above-mentioned components onto a suitable support such as paper, synthetic paper, or plastic film, and drying the coating solution. In this case, the amounts of the leuco dye, color developer, and color development sensitivity enhancer used are 5 to 40% by weight and 20% by weight, respectively.
-60% by weight, 20-60% by weight is suitable.

〔effect〕

The heat-sensitive recording material of the present invention has improved sensitivity, is suitable for high-speed recording, and has a high background whiteness, making it extremely practical.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples. Note that all parts and percentages shown below are based on weight.

Example 1 The following liquids (A) to (03) were prepared by separately grinding and dispersing mixtures having the following compositions using a magnetic ball mill for two days.

[Liquid A]

3-(N-cyclohexyl-N-methyl)amino-6-
Methyl-7-anirite fluorane 20 parts 10% aqueous solution of hydroxyethyl cellulose 20 parts Water
60 [Liquid B] Bisphenol A 20 parts 10% aqueous solution of hydroxyethyl cellulose in water
61 [Liquid C] α,α'-diphenoxy 0-xylene (compound of Compound Example No. L5, melting point 78-79°C) 20 5% aqueous solution of methylcellulose 20 parts water
60
I/[Liquid D] Calcium carbonate 20 parts Methyl cellulose 5% aqueous solution 20 parts Water
6o then A
10 parts of liquid B, 30 parts of liquid C, 20 parts of liquid D, and 10 parts of a 20% alkaline aqueous solution of isobutylene-maleic anhydride copolymer were mixed to prepare a thermosensitive coloring layer forming liquid, which had a basis weight of 50 g. /rdl' dry adhesion on high quality paper is 4 ~
A heat-sensitive coloring layer was provided by coating and drying to give a coating weight of 5 g/rd, and then the layer surface was calendered to give a surface smoothness of 500 to 600 seconds to prepare a heat-sensitive recording material.

Example 2 Thermal recording material (b) was prepared in the same manner as in Example 1 except that the following liquid (E) was used instead of the liquid CB) in Example 1.
It was created.

(E) Liquid P-Hydroxybenzoic acid benzyl ester 20 parts 10% aqueous solution of hydroxyethyl cellulose 20 parts water
60 Example 3 Thermal recording material (C) was prepared in the same manner as in Example 1 except that the following liquid (F) was used instead of liquid (B) in Example 1.
It was created.

[F] Liquid 1.7-di(4-hydroxyphenylthio)-3,5-
Dioxahebutane 20 parts 10% aqueous solution of hydroxyethylcellulose 20 parts Water 6 parts
0 Example 4 Thermal recording material (d) was prepared in the same manner as in Example 1 except that the following liquid (G) was used instead of liquid (B) in Example 1.
It was created.

CG) Solution 4.4'-Dihydroxydiphenylsulfone 20 parts 10% aqueous solution of hydroxyethyl cellulose 20〃 Water 6
0 Comparative Example 1 Example 1 except that water was used instead of liquid (C) in Example 1.
A thermosensitive recording material (e) was prepared in the same manner as above.

Comparative Example 2 A heat-sensitive recording material (f) was prepared in the same manner as in Example 2 except that water was used instead of liquid (C) in Example 2.

Comparative Example 3 Example 3 except that water was used instead of liquid (C) in Example 3.
A heat-sensitive recording material (g) was prepared in the same manner as above.

Comparative Example 4 Example 4 except that water was used instead of liquid (C) in Example 4.
A thermosensitive recording material (h) was prepared in the same manner as above.

Comparative Example 5 A thermosensitive recording material (i) was prepared in the same manner as in Example 1, except that the following liquid (H) was used instead of liquid (C) in Example 1.

(H) Liquid stearamide 20 parts 5% aqueous solution of methylcellulose 20 parts water
60 parts Comparative Example 6 A heat-sensitive recording material (j) was prepared in the same manner as in Example 2, except that the liquid (H) was used instead of the CC1 liquid in Example 2.

Comparative Example 7 A heat-sensitive recording material (k) was prepared in the same manner as in Example 3, except that the liquid (H) was used instead of the liquid (C) in Example 3.

Comparative Example 8 A heat-sensitive recording material (1) was prepared in the same manner as in Example 4, except that the liquid (H) was used instead of the liquid (C) in Example 4.

Thermosensitive recording materials (a) to (1) obtained as above.

Using a thermal printing experimental device with a thin film head manufactured by Matsushita Electronics Co., Ltd., the head power was 0.451/dot, the recording time per line was 20 m5ecIQ, and the scanning line density was 8 x 3.85 dots/dot.
The pulse width is 1.6.2.0.2.4 (ms
ec), and the print density is measured using a Macbeth Densitometer RD-
514 (filter V-106). The results are shown in Table-1.

Table 1 Next, heat sensitive recording materials (a) to (1) were subjected to a 24 hour storage test under dry conditions at 60"C to examine changes in skin density. The results are shown in Table 2.

Table 2 From the above results, it can be seen that the heat-sensitive recording material of the present invention has high color development sensitivity, is suitable for high-speed recording, and also has high background whiteness, making it an extremely practical heat-sensitive recording material.

Claims (1)

[Claims] (1) In heat-sensitive recording materials that utilize the color-forming reaction between leuco dye and its color developer, there are general formulas, ▲mathematical formulas, chemical formulas, tables, etc. as auxiliary components▼(I) [In the formula, R_1 is General formula -R_2-Ar-R_3-(II) (wherein, Ar is a substituted or unsubstituted arylene group, R
_2 and R_3 represent a lower alkylene group) or a general formula, ▲Mathematical formula, chemical formula, table, etc.▼(III) (In the formula, R_4 and R_5 represent a hydrogen atom, lower alkyl, or a substituted or unsubstituted aryl group) , at least one of which is a substituted or unsubstituted aryl group, m and n are 0 or a positive integer), and X and Y are an alkyl group, a halogen Indicates an atom, alkoxy group, aryl group or aralkyl group,
A heat-sensitive recording material characterized in that a diether compound represented by the following formula is used in combination: k and l may be the same or different, and k and l represent integers of 0 to 5.