JPS62121089A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material having sufficient developed color density and color forming sensitivity, suitable for high-speed recording and having a high ground brightness, by using at least one compound of a specified formula as an auxiliary component. CONSTITUTION:A compound of formula (I) is used as an auxiliary component in a thermal recording material utilizing a color forming reaction between a leuco dye and a color developer therefor. In formula (I), each of R1 and R2 is independently an alkyl, alkoxyl, halogen, aryl, aralkyl, acyl or aryl which may have a substituent such as acyloxyl, and R2 is alkylene or aralkylene. From the viewpoints of preservation stability and sensitivity of the thermal recording material, the above compound preferably has a melting point of 60-120 deg.C. The amounts of the leuco dye, the color developer and the color forming sensitivity increasing agent used are suitably 5-40wt%, 20-60wt% and 20-60wt%, respectively. The thermal recording material is produced by applying a coating liquid containing the above components to an appropriate base such as a paper, a synthetic paper and a plastic film, followed by drying.

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 improved color development sensitivity suitable for high-speed recording.

[Prior art]

General heat-sensitive recording materials are coated on a support such as paper or film, and contain a colorless or light-colored color-forming dye such as a leuco dye as a color-forming agent, and a phenolic compound (especially bisphenol A) as a color-developing agent to cause the dye to develop specific heat color. A heat-sensitive coloring layer in which a binder, a filler, a sensitivity improver, a lubricant, and other auxiliary agents are further dispersed in a coloring system made of an acidic substance such as an organic acid is provided. 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 the advantages of
It is useful as a recording material for various information and measuring instruments such as 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. The second method is, 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, the heat-sensitive recording materials produced based on these methods are still not sufficient in terms of color density, color sensitivity, background whiteness, etc.

〔the purpose〕

An object of the present invention is to provide a heat-sensitive recording material that has sufficient color density and color sensitivity, is suitable for high-speed recording, has high background whiteness, and is highly practical.

〔composition〕

According to the present invention, in a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and its color developer, at least one compound selected from the compounds represented by the following general formula (1) is added as an auxiliary component. A heat-sensitive recording material characterized in that it is used is provided.

R1-0-R2-S R3(1) (wherein R and R3 each independently represent an alkyl group, an alkoxy group, a halogen atom, an aryl group, an aralkyl group,
It represents an aryl group which may have a substituent such as an acyl group or an acyloxy group, and R2 represents an alkylene group or an aralkylene group. ) The compound represented by the general formula (1) used as an auxiliary component in the present invention preferably has a melting point of 40 to 150°C, particularly 60 to 120°C, from the viewpoint of storage stability and sensitivity as a heat-sensitive recording material. ℃ is preferred. Specific examples are shown below, but the present invention is not limited thereto.

Compound No. #1 Formula The leuco dyes used in the present invention can be applied singly or in a mixture of two or more types, but such leuco dyes include:
Those applied to this type of heat-sensitive material can be arbitrarily applied. For example, leuco compounds of dyes such as triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, and indolinophthalide-based dyes are preferably used. .

Specific examples of such leuco dyes include, for example.

Examples 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-diethylaminophenyl, 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-ditylamino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7- Anilinofluorane, 2- (N-(3'-trifluoromethylphenylamino)-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) Fluorane.

3-dibutylamino-7-(o-chloroanilino)fluoran, 3-N-methyl-N-isoamylamino-6-methyl-
7-anilinofluorane.

37N-Methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane.

3-diethylamino-6-methyl-7-anilinofluorane, 3-(N,N-diethylamino)-5-methyl-7-(
N.

N-dibenzylamino)fluoran.

Benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrylospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrylospirane, 3-(2'-hydroxy-4'-dimethylami, nophenyl) )-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)fluoran, 3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluoran, 3-diethylamino-5-chloro-7-(α-phenylethylamino)fluoran, 3-(N-ethyl-p-toluidino)-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-(o-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-( α-phenylethylamino)fluorane, 3-diethylamino-7-piperidinofluorane, 2nichloro-3-(N-methyltoluidino)-7-(p-n
-butylanilino)fluoran, 3-(N-benzyl-N-cyclohexylamino)-5
, 6-penzo 7-α-naphthylamino-4'-bromofluorane.

3-diethylamino-6-chloro-7-anilinofluorane, 3-N-ethyl-N-(2-ethoxypropyl)amino-6-methyl-7-anilinofluorane.

3-N-ethyl-N-tetrahydrofurfurylamino-
6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-mesitidino 4', 5'-benzofluorane, and the like.

As the color developer used in the present invention, various electron-accepting compounds, such as phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof, are preferably used, and the specific examples thereof are as follows. Give an example.

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-jert, butyl-
2methyl)phenol, 4.4'-thiobis(6-tertbutyl-2-methyl)phenol, 4.4'-diphenolsulfone, 4.4'-diphenol sulfoxide, isopropyl P-hydroxybenzoate, Benzyl P-hydroxybenzoate, Benzyl protocatechuate, Stearyl gallate, Lauryl gallate, Octyl gallate, 1,7-bis(4-hydroxyphenylthio)-3,5
-dioxahebutane, 1,5-bis(4-hydroxyphenylthio)-3-oxapentane.

1.3-bis(4-hydroxyphenylthio)-propane, (1), 3-bis(4-hydroxyphenylthio)-2-hydroxypropane, N,N'-diphenylthiourea.

N,N'-di(ffi-chlorophenyl)thiourea.

salicylanilide, 5-chloro-salicylanilide, salicyl-〇-chloroanilide, 2-hydroxy-3-naphthoic acid, 2-hydroxy-1-naphthoic acid, l-hydroxy-2-naphthoic acid, zinc hydroxynaphthoic acid, Metal salts such as aluminum and calcium.

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 In addition to water-soluble polymers such as , styrene/maleic anhydride copolymer alkali salt, inbutylene/maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, polyvinyl acetate, polyurethane, styrene/ Butadiene copolymer, polyacrylic acid, polyacrylic ester, vinyl chloride/
Vinyl acetate copolymer, polybutyl methacrylate-1-, ethylene/vinyl acetate copolymer, styrene/butadiene/
Latex such as acrylic copolymer 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 may be added.

For example, fillers, surfactants, thermofusible substances (or lubricants)
etc. can be used together. In this case, the filler is
For example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate,
Examples include inorganic fine powders such as clay, talc, and surface-treated calcium and silica, as well as organic fine powders such as urea-formalin resin, styrene/methacrylic acid copolymer, and polystyrene resin.

The heat-sensitive recording material of the present invention is produced, for example, by applying a heat-sensitive layer-forming coating solution containing each of the above-mentioned components onto a suitable support such as synthetic paper or plastic film, and drying. 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 and is suitable for high-speed recording.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.6 Note that all parts and percentages shown below are based on weight.

Example 1 The following mixtures were each pulverized and dispersed in a magnetic ball mill for two days to prepare liquids A, B, and C.

[Liquid A]

10% 2Qn aqueous solution of 3-(N-methyl-N-cyclohexyl 20 parts amino)-6-methyl-7-anilite fluoran hydroxyethylcellulose
60II [Liquid B] Bisphenol A 20 parts 10% aqueous solution of hydroxyethylcellulose 20/! water
60
[Liquid C] 20 parts of 1-phenoxy-2-(β-naphthylmercapto)ethane (compound of Compound Example No. 4, melting point 86-88°C) 20 parts of a 5% aqueous solution of methylcellulose Water
60//[Liquid D] Calcium carbonate 20 parts Methyl cellulose 5% aqueous solution 20! ! water
60
//Next, 10 parts of liquid A, 30 parts of liquid 8, 30 parts of liquid C, 2 parts of liquid D.
0 parts and 20 parts of inbutylene-maleic anhydride copolymer
% alkaline aqueous solution to form a thermosensitive coloring layer forming solution, which was coated and dried on high-quality paper with a basis weight of 50 g/m to a dry adhesion weight of 4 to 5 g/rd to form a thermosensitive coloring layer. After that, the layer surface was further calendered to obtain a heat-sensitive recording material (a
)It was created.

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! ! water
6
0 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-bis(4-hydroxyphenylthio)-3,5
-Dioxahebutane 20 parts 10% aqueous solution of hydroxyethyl cellulose in water
6olI Comparative Example 1 Example 1 except that water was used instead of liquid [C] in Example 1.
A thermosensitive recording material (d) was prepared in the same manner as above.

Comparative Example 2 A heat-sensitive recording material (e) 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 A heat-sensitive recording material (f) was prepared in the same manner as in Example 3 except that water was used instead of liquid [C] in Example 3.

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

CG) Liquid stearamide 20 parts 5% aqueous solution of methylcellulose 20 parts water
601
Comparative Example 5 A heat-sensitive recording material (h) was prepared in the same manner as in Example 2, except that the liquid (G) was used instead of the liquid (C) in Example 2.

Comparative Example 6 A thermosensitive recording material (i) was obtained in the same manner as in Example 3, except that the liquid CG) was used instead of liquid [C] in Example 3.

The heat-sensitive recording materials (a) to (i) obtained as described above are
Using a thermal printing experimental device with a thin film head manufactured by Matsushita Electronics Co., Ltd., the pulse width was set to 1.6. 2.0.2.4(
msec), and the print density is measured using Macbeth Densitometer R.
Measured with D-514 (filter W-106). The results are shown in Table-1.

Table-1 As is clear from Table 1, the thermal recording of the present invention.

It can be seen that the material has excellent color development during high-speed recording.

Claims (1)

[Claims] (1) A thermosensitive recording material that utilizes a color-forming reaction between a leuco dye and its color developer, characterized in that it uses at least one compound selected from the compounds represented by the following general formula as an auxiliary component. Recording materials. R_1-O-R_2-S-R_3 (wherein R_1 and R_3 each independently represent an alkyl group,
It represents an aryl group which may have a substituent such as an alkoxy group, a halogen atom, an aryl group, an aralkyl group, an acyl group, or an acyloxy group, and R_2 represents an alkylene group or an aralkylene group. )