JPH0243085A - heat sensitive recording material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a heat-sensitive recording medium, in particular, it has excellent storage stability of recorded images, does not reduce the whiteness of blank paper areas, and is suitable for preventing sticking and thermal heads. The present invention relates to a heat-sensitive recording material with little residue adhesion.

(Prior Art and Problems to be Solved) Heat-sensitive recording paper containing a leuco compound and an organic acid, for example,
It is already known from No. 14039 and the like. This recording paper is based on the principle that thermal energy is applied to the recording layer to soften or melt the leuco compound, organic acid, and binder, and the two coloring components are brought into contact to cause a coloring reaction. It is used in fields such as IJ.

The recording characteristics of this recording paper vary depending on the application, but as its usage has become more widespread, it has become important to not only be suitable for high-speed recording, but also to maintain the stability of recorded images under high temperature and high humidity conditions, and to avoid unnecessary fogging in blank areas. It is required to have the following characteristics.

Conventionally, various methods have been proposed for the purpose of improving the archivability of recorded images. For example, JP-A-49-45747 and JP-A-49-54040 propose the addition of various phenol derivatives.

However, according to these techniques, 1. The effect of preventing fading is not sufficient; 2. 3. If a fingerprint gets on the colored part, the color will fade. 4. It has the disadvantage that if a fingerprint is attached to the uncolored part, the color will develop, so it is not suitable for practical use. In addition, in JP-A-53-17346, JP-A-53-17347, and JP-A-55-34901, the addition of various resins has been proposed, and although some of them have a tolerable effect,
When used as a thermal recording medium, new problems such as sticking and adhesion of residue to the thermal head arise.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a thermal recording medium which has excellent storage stability of recorded images, does not reduce the whiteness of blank paper portions, and exhibits less sticking and adhesion of residue to the thermal head.

(Means for Solving the Problems) As a result of intensive studies to achieve the above object, the present inventors discovered that a thermosensitive recording material containing a leuco compound and an organic acid that develops a color by reacting with the leuco compound as a main component. In the heat-sensitive recording layer, tris(3-methyl-5-tert-butyl- 4-
The present inventors have discovered that the above object can be achieved by incorporating hydroxybenzyl) in cyanurate (hereinafter referred to as compound (I)), and have accomplished the present invention.

The present invention will be explained in detail below.

The heat-sensitive recording material of the present invention comprises a leuco compound, an organic acid as a color developer, a binder, and a compound (
It consists of a heat-sensitive recording layer containing 1) coated on a support.

This compound (I) is generally 2-methyl-6tert-"
It is obtained by heating and reacting 3 moles of methylphenol, formalin, for example, 3 moles of paraformaldehyde, and 1 mole of cyanuric acid in an organic solvent in the presence of an amine catalyst. Compound (1) is 1 to 50% by weight, preferably 1 to 30% by weight of the total solid content of the heat-sensitive recording layer.
It shows sufficient effect when used in

In the present invention, a known storage improver may be included in the recording layer together with compound (1).

The leuco compounds used in the present invention are colorless to light-colored substances that develop color by reacting with organic acids, such as triphenylmethane, triphenylmethane phthalide, fluoran, leuco auramine, and diphenylmethane. system,
Examples include various derivatives such as phenothiazine, phenoxazine, spiropyran, indoline, and indigo derivatives. Preferred leuco compounds include, for example, crystal bioleft lactone, 3-diethylamino-6methyl-7-anilinofluoran, 3-(N-ethyl-P-
) luidino)-6-methyl-7-anilinofluorane,
3-diethylamino-6-methyl-7-(ortho, para-dimethylanilino)fluorane, 3-pyrrolidino-6
-Methyl-7-anilinofluorane, 3-piperidino-
6-Methyl 7-anilinofluorane, 3-(N-cyclohexyl-N-methylamino)-6-methyl-7anilinofluorane, 3-diethylamino-7(ortho-chloroanilino)fluorane, 3-diethylamino -7-(
meta-trifluoromethylanilino)fluorane, 3-
Diethylamino-6-methyl-chlorofluorane, 3-diethylamino-6-methyl-fluorane, 3-cyclohexylamino-6-chlorofluorane, 3-(N-isoamyl-N-ethylamino)-6-methyl-7anilino Examples include fluoran and 3-dibutylamino-6-methyl-7-anilinofluoran.

The organic acid used in the present invention is a substance that is solid at room temperature, melts by heating, and becomes a color developer when it comes into contact with a leuco compound, and includes various phenolic substances, fatty acids, aromatic carboxylic acids, and the like. Examples include gallic acid, salicylic acid, 1-hydroxy-2-naphthoic acid, 0-hydroxybenzoic acid, m-hydroxybenzoic acid, 2-hydroxy-p-
) Ruylic acid, 3.5-xylenol, thymol, p-t
ert-butylphenol, 4-hydroxyphenoxide, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, α-naphthol, β-naphthol, catechol, resorcinol, hydroquinone, 4-ter
t-octylcatechol, 4°4'-5ec-butylidenephenol, 2.2'dihydroxydiphenyl, 2.
2'-methylenebis(4-methyl-6-tert-butylphenol), 2.2'-bis(4'-hydroxyphenyl)furopane (also known as bisphenol A), 4.
4'isopropylidene-bis(2-tert-butylphenol), pyrogallol, phloroglucin, 70loglucincarboxylic acid, p-methylphenol, p-phenylphenol, 4.4'-cyclohexylidene diphenol, 4.4'- (1-methyl n-hexylitine) diphenol, 4.4' isopropylene dicatechol, 4.4'-benzylidene diphenol, 4.4'
-isopropylidene bis(2-chlorophenol), 3
-7enylsalicylic acid, 3.5-di-tert-butylsalicylic acid, -oxy-2-naphthoic acid, gallic acid ester, salicylic acid ester, p-hydroxybenzoic acid ester, 4-hydroxyphthalic acid ester, 2-(4
-hydroxyphenyl)-2-(3'hydroxyphenyl)propane, 4,4'-dihydroxy-3,3'
-diisopropyldiphenyl-2,2'-propane and the like.

The binder used in the present invention is mainly a water-soluble binder, which separates and fixes the coloring agent dispersed in fine particles from each other, and includes polyvinyl alcohol, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, Examples include acrylic acid, casein, gelatin, starch and derivatives thereof.

The heat-sensitive recording layer of the present invention may optionally contain other additives, such as clay, synthetic silica, calcium carbonate, aluminum hydroxide, talc, titanium oxide, zinc oxide, and other inorganic or organic pigments, and waxes. , an antioxidant for storage stability, an ultraviolet absorber, various fatty acid metal salts to prevent stickiness, a water resistant agent to improve water resistance, a phenol resin, a surfactant, etc. can be added.

The paint for a heat-sensitive recording layer of the present invention comprises the above-mentioned leuco compound,
Organic acid, compound (1), and additives such as pigments and sensitivity adjusters as necessary are crushed in an aqueous medium containing a binder such as polyvinyl alcohol at an appropriate concentration using a pulverizer such as a ball mill or a sand grinder. It is generally prepared by grinding and dispersing using. It is advantageous in terms of color development efficiency to make each constituent material as fine as possible, and it is preferable to make the particles as fine as possible to a particle size of 0.5 to 3 .mu.m. The heat-sensitive dye thus obtained is applied to the support described below and dried to obtain the heat-sensitive recording material of the present invention.

Coating can be done using a regular blade coater, air knife coater,
This can be done using a bar coater, reverse roll coater, or the like.

The support used in the present invention generally includes high-quality paper,
Papers such as medium-quality paper and coated paper are used, but other materials such as glass fiber sheets, plastic sheets, and film-laminated papers can also be used as the support.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

Synthesis Example> In a 5β autoclave equipped with a thermometer and a stirring device, 4.2-methyl-6-tert-butylphenol was added.
63.2g, cyanuric acid 116.4g, paraformaldehyde 97.7g, hexamethylenetetramine 4.0g
, 982.5 g of acetonitrile, and 218.2 g of distilled water.
After the reaction system was sufficiently purged with nitrogen, stirring and heating was started. After continuing heating at a temperature of 115°C for 6 hours,
After cooling to room temperature, the slurry-like reaction solution was taken out from the autoclave.

Acetonitrile 300+ni in the reaction solution! After adding the crystals, the crystals were filtered off under reduced pressure and dried under reduced pressure at 80°C for 2 hours. Furthermore, recrystallization was performed from ethanol 2β.
9 g of tris(3-methyl-5tert-butyl-4
-hydroxybenzyl) isocyanurate (compound (
1)) (white crystals, melting point 199.5°C) was obtained.

(Analytical value) H-NMR absorption spectrum [CDCA 3. δ(ppm)] 1.37 (27)1. s)2.16
(9H, s) 4.94 (9H, s) 7.03-7.45 (6H, m) rR absorption spectrum [KBr, wave! (cm-')ko350Q, 2940. 1670. 1440.
1310°1170, 750 Example 1 Solutions A and B having the following compositions were prepared by shaking each separately in a paint shaker (manufactured by Toyo Seiki) for 10 hours.

Solution A: 3-dibutylamino-6-methyl-7-anilinofluorane (leuco dye) g zinc stearate 5 g polyvinyl alcohol 12% solution 35 g water
50g Solution B: Bisphenol A 15g Compound (I) 10g Zinc stearate 3g Polyvinyl alcohol 1
2% $ 35g water
47g Next, add 11g of B liquid to 95g of A liquid.
0 g, 50 g of 12% polyvinyl alcohol solution, 15 g of synthetic silica P-832 (manufactured by Mizusawa Chemical Co., Ltd.) and 60 g of water were added and mixed with stirring to prepare a coating liquid. Next, apply this coating liquid for 5
It was coated on the surface of 0 g/m' high-quality paper using a Mayer bar so that the coated amount after drying was 8 g7 m2, and dried to obtain heat-sensitive recording paper.

Comparative Example 1 A thermosensitive recording material was obtained in exactly the same manner as in Example 1 except that compound (1) was omitted from the formulation of liquid B used in Example 1.

Comparative Example 2 In the formulation of liquid B used in Example 1, 4,4'-butylidenebis(3-methyl-6-te) was used instead of compound (I).
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that rt-butyl-m-cresol was used.

Comparative Example 3 In the formulation of Solution B used in Example 1, 4.4'-thiobis(6-tertbutyl-m
A thermosensitive recording paper was obtained in the same manner as in Example 1, except that 1-cresol) was used.

Comparative Example 4 Among the formulations of liquid B used in Example 1, 1. 1. A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 3-)lis(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane was used.

Comparative Example 5 A thermosensitive recording paper was obtained in the same manner as in Example 1 except that a terpene-modified phenol resin was used in place of compound (I) in the formulation of liquid B used in Example 1.

Comparative Example 6 A thermosensitive recording paper was obtained in the same manner as in Example 1, except that in the formulation of liquid B used in Example 1, rose octylphenol resin was used instead of compound (1).

Example 2 A thermosensitive recording paper was obtained in exactly the same manner as in Example 1 except that benzylbara hydroxybenzoate was used instead of bisphenol A in the formulation of liquid B used in Example 1.

Example 3 In the formulation of liquid B used in Example 1, n-butyl-bis(4-hydroxyphenyl) was used instead of bisphenol A.
A thermosensitive recording paper was obtained in exactly the same manner as in Example 1 except that acetate was used.

Example 4 Thermosensitive recording paper was obtained in exactly the same manner as in Example 1, except that 4-hydroxy-4'-isopropoxy-diphenylsulfone was used instead of bisphenol A in the formulation of liquid B used in Example 1. Ta.

The characteristics of the thermal recording papers (samples) obtained in the above Examples and Comparative Examples were evaluated by the test method described below.

1. High temperature and high humidity storage test After printing with a commercially available heat-sensitive facsimile machine UP-1000 (Matsushita Densen@), the temperature is 40℃, the humidity is 90%, and the temperature is 6.
The samples were stored for 24 hours under two conditions: dry smoke (R815%) at 0°C, and the skin density of the samples before and after storage was measured.

Separately, the density of the printed area of the sample before and after storage was measured, and the residual rate of the density of the printed area after storage was determined from the following formula.

The results of the above tests are shown in Table 1.

All color density measurements were made using the Macbeth density system RD-5.
I went with 14 type.

2. Light resistance storage test After printing with the same UP-1000, the sample was exposed to sunlight for one week, and then the background density of the sample was measured. The density of the printed area after separate exposure was measured, and the residual rate of the density of the printed area was determined in the same manner as in the storage test.

3. Sticking test Printing was performed using UF-1000 in an atmosphere of 0°C, and the presence or absence of sticking was examined at that time.

4. Dust adhesion test A 3 mm solid pattern was performed using UF-1000 in an atmosphere of 20°C, and dirt around the thermal head was visually determined.

As can be seen from Table 1, the compound of the present invention (
By incorporating I), it is possible to obtain a heat-sensitive recording material that has excellent storage stability of recording density, has little fogging of background density, and has little sticking and adhesion of residue to the head.

Claims (1)

[Scope of Claims] A heat-sensitive recording material comprising, on a support, a heat-sensitive recording layer containing a leuco compound, an organic acid that develops a color by reacting with the leuco compound, and a binder, wherein the heat-sensitive recording layer It contains the following structural formula (I): ▲Mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R represents a tert-butyl group.) Tris (3-methyl-5-tert-butyl) A thermosensitive recording material characterized by containing -4-hydroxybenzyl) isocyanurate.