JPS62242581A - 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 [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 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. One example is a coloring system comprising an acidic substance such as an organic acid, and a heat-sensitive coloring layer in which a binder, a filler, a sensitivity improver, a lubricant, and other auxiliary agents are dispersed.

It was introduced in Japanese Patent Publication Sho/+3-4160, Japanese Patent Publication No. 45-14039, and Japanese Patent Application Laid-open No. 48-27736, and 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 of this, compared to other recording materials, recording can be obtained in a short time using relatively simple equipment without complicated processes such as development and fixing, and there is less noise and environmental pollution, and the cost is lower. Due to its low cost, it is also used for copying books, documents, etc.

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

On the other hand, in recent years, with the development of society, the demand for higher speed and higher recording density has increased, so there is a strong desire not only to increase the speed of the recording device itself, but also to develop recording materials that can meet this demand. . 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.

The phenolic compound itself is expensive and has little practical use. As a second method, for example, JP-A-53-3013
No. 9, JP-A-53-26139, JP-A-53-563
No. 6, JP-A No. 53-11036, etc., the heat-sensitive coloring layer contains various waxes, fatty acid amides, alkylated biphenyls, substituted biphenylalkanes, coumarins, diphenylamines, etc. with low melting points. There is a method of adding a melting substance as a sensitizer (or melting point depressant). However, it is fair to say 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 first object of the present invention is to have sufficient color development sensitivity per color density,
The purpose is to provide a highly practical heat-sensitive recording material that is suitable for high-speed recording, has high background whiteness, and has sufficient color density and sensitivity, is suitable for high-speed recording, and Extremely practical, with high background whiteness, no color development on the background or decoloration of colored areas even when in contact with oils or plasticizers, and no decrease in image density when in contact with water, such as when immersed in water. The object of the present invention is to provide a heat-sensitive recording material with high heat resistance.

〔composition〕

According to the present invention, as a first invention, in a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and its color developer, an auxiliary component of the general formula
~8 alkyl groups.

R3, R4, R6 and R6 are hydrogen atoms or have 1 to 8 carbon atoms
represents an alkyl group, provided that R5 and R6 are not hydrogen atoms at the same time. ) A heat-sensitive recording material is provided, characterized in that it uses a monophenol compound represented by:
In a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and its color developer, the color developer has the general formula (n) (R) kZn(X) z (II) (
Zinc represented by While using a complex, as an auxiliary component, the general formula (summer) (in the formula, R2 represents an alkyl group having 1 to 8 carbon atoms).

R3, R4, R5 and R6 represent a hydrogen atom or an alkyl group of C□ to C♂. However, R5 and R6 are not hydrogen atoms at the same time.) A heat-sensitive recording material characterized in that a monophenol compound represented by the following is used in combination is provided.

The monophenol compound represented by the general formula (1), which is used in combination as an auxiliary component in the present invention, is a color developer (electron-accepting compound) and a leuco dye (electron-donating colorless dye) that are widely used. By adjusting the melting point of the monophenol compound used in combination,
A heat-sensitive recording material of any sensitivity can be obtained, and since the background whiteness is also excellent, a heat-sensitive recording material suitable for high-speed recording can be obtained.

The monophenol compound used in the present invention has a melting point of 40 to 150 from the viewpoint of storage stability and sensitivity as a heat-sensitive recording material.
℃ is preferable, and 50 to 120 ℃ is particularly preferable. Specific examples of the monophenol compound of the present invention are shown below, but the present invention is not limited thereto.

Compound surface Structural formula Furthermore, the present invention provides a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and its color developer, in which a zinc complex represented by the formula (II) is used as the color developer. In addition, the present invention provides a heat-sensitive recording material characterized in that at least one kind selected from the monophenol compounds represented by the above formula (1) is used as an auxiliary component.

In this case, one color density and one color sensitivity are sufficient, it is suitable for high-speed recording, and the whiteness of the background is high, and there is no coloration on the background or decolorization of the coloring area even when it comes into contact with oils or plasticizers. It is possible to obtain an extremely practical heat-sensitive recording material whose image density does not decrease even when it comes into contact with water, such as when immersed in water.

Examples of the zinc complex represented by the general formula (n) used in the present invention include the following compounds, which are the same as the color developer conventionally used in this type of heat-sensitive recording material as described below. It is also possible to use them together.

[Zinc complex]

The leuco dyes used in the present invention can be applied singly or in combination 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. Nine.

A specific example of such a leuco dye is as follows.

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-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-ethylamino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilino Fluorane.

2-(N-(3'-trifluoromethylphenyl)amino)-6-dinithylaminofluorane.

2-(3,6-bis(diethylamino)-fl-(
o-chloroanilino)xantylbenzoic acid lactam),
3-diethylamino-6-methyl-7-(+w-trichloromethylanilino)fluoran.

3-diethylamino-7-(o-chloroanilino)fluoran.

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

3-N-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-31-methoxy-benzoindolino-pyrylospirane, 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-41-diethylaminophenyl)-3-(2'-methoxy-5'-methylphenyl)phthalide, 3-(2'-methoxy-4'-dimethylaminophenyl)-3-(2'-hydroxy- 4'-chlor-51
-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-? -(o-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-42-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.

In the present invention, the color developer that can be used in combination with the auxiliary component represented by the general formula (1) and the color developer represented by the general formula (I Compounds, thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof, etc. are preferably used, and specific examples thereof are shown below.

4.4'-isopropylidene bisphenol, 4.4
′ -isopropylidene bis(O-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'-butylidene bis(6-t, ertbutyl-
2 methyl) 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(m-chlorophenyl)thiourea, salicylanilide, 5-chloro-salicylanilide, salicyl-〇-chloroanilide.

2-hydroxy-3-naphthoic acid, 2-hydroxy-1-naphthoic acid, 1-hydroxy-2-naphthoic acid, 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, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose and other cellulose derivatives, 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, isobutylene-maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, polyvinyl acetate, polyurethane, styrene/butadiene Copolymer, polyacrylic acid, polyacrylic ester, vinyl chloride
Latex such as vinyl acetate copolymer, polybutyl methacrylate, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer, etc. can be used.

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, fillers include 1, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and surface-treated inorganic fine powders such as calcium and silica. ,
Examples include organic fine powders such as urea-formalin resin, styrene/methacrylic acid copolymer, and polystyrene resin.

The heat-sensitive recording material of the present invention can be produced, for example, by applying a coating liquid for forming a heat-sensitive layer containing each of the above-mentioned components onto a suitable support such as paper 1 synthetic paper or plastic film, and drying it. . In this case, the amounts of leuco dye, color developer, and color development sensitivity enhancer used are:

5 to 40 weight%, 20 to 60 weight%, 20 to 6 weight% respectively
0% by weight is suitable.

〔effect〕

The heat-sensitive recording material of the first invention uses the compound represented by the general formula (1) as an auxiliary component.

It has improved sensitivity, is suitable for high-speed recording, and has high background whiteness, making it highly practical.

The heat-sensitive recording material of the second invention uses the general formula (
Since the zinc complex represented by 11) is used and the compound represented by the general formula (1) is used as an auxiliary component, the sensitivity is improved, making it suitable for high-speed recording, and the whiteness of the background is high. Moreover, it is extremely practical because it does not develop color in the background or decolorize the colored area even when it comes into contact with oils or plasticizers, and the image density does not decrease even when it comes in contact with water, such as when immersed in water. .

〔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 [ΔLiquid] 10% 2o aqueous solution of 3-(N-methyl-N-cyclohexyl 20 parts amino)-6-methyl-7-anilite fluoran hydroxyethyl cellulose
60 [Liquid B] Bisphenol A 20 parts 10% 2Qu aqueous solution of hydroxyethyl cellulose
6011 [Liquid C] 2.3.5-trimethylphenol 20 parts (compound of Compound Example No. 2, melting point 95°C) 5% aqueous solution of methylcellulose 20 parts water
60〃[D
Liquid] Calcium carbonate 20 parts Methyl cellulose 5% aqueous solution 29n water
60
Next, add 10 parts of liquid A, 30 parts of liquid B, 30 parts of liquid C, and 20 parts of liquid D.
part and 20% of isobutylene-maleic anhydride copolymer
10 parts of alkaline aqueous solution are mixed to form a thermosensitive color forming layer forming liquid, and this is applied to a high-quality paper with a basis weight of 50 g/- with a dry adhesion weight of 4 to 4.
After coating and drying to form a heat-sensitive coloring layer at a concentration of 5 g/trr, the layer surface was further calendered to a surface smoothness of 500 to 600 seconds to obtain a heat-sensitive recording material (0).
It was created.

Example 2 A heat-sensitive recording material (b
)It was created.

[E] Liquid P-hydroxybenzoic acid benzyl ester 20 parts 10% aqueous solution of hydroxyethyl cellulose 20 parts water
60
7F 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 20 parts Water
60 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 the C3 liquid.

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 [G] was used instead of liquid (C) in Example 1.

(G) Liquid stearamide 20 parts 5% aqueous solution of methylcellulose 20 parts water
60 Comparative Example 5 A heat-sensitive recording material (h) was prepared in the same manner as in Example 2, except that the above liquid [G] was used instead of 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 (G) was used instead of the 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 Matsushita Electronics TM film head, the pulse width was set to 1.6 with head power of 0.451/dot, l-line recording time of 20+wsac/Q, and scanning line density of 8 x 3.85 dots/+n+. .2.0.2.
4 (+++5 ec), and the print density was measured using a Macbeth densitometer RD-514 (Filterly 106). The results are shown in Table-1.

Table 1 Next, heat-sensitive recording materials (a) to (i) were subjected to a 24-hour storage test under dry conditions at 60° C., and changes in skin density were examined. 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 first 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.

Next, the second invention will be explained in more detail with reference to examples.

Note that all parts and percentages shown below are based on weight.6 Furthermore, the antipyrine complex of zinc thiocyanate (compound No. 1) used in the examples described later was synthesized in the following manner.

14.4 g of zinc sulfate (Zn5044Hz 0) and 29.2 g of potassium thiocyanate were dissolved in 200 μa of water.

Separately, a solution of 8.8 g of antipyrine dissolved in 200 mQ of water was prepared, and when the solution was added dropwise to the above solution while stirring, a white precipitate was immediately generated. This precipitate was filtered, washed with water, dried, and the obtained white powder was recrystallized from a mixed solvent of water and ethanol to obtain 24.2 g of white crystals of an antipyrine complex of zinc thiocyanate with a melting point of 118 to 120°C. Ta.

Example 4 The following liquids (A) to (D) were prepared by separately pulverizing and dispersing mixtures having the following compositions for two days using a magnetic ball mill.

[Liquid A]

3-(N-cyclohexyl-N-methylamino-6-methyl-7-anilite fluorane 20 parts 10% aqueous solution of hydroxyethylcellulose 20 parts water
60 parts [Liquid B] Antipyrine complex of zinc thiocyanate 20 parts 5% aqueous solution of methylcellulose 20 parts water
60 copies [
Solution C] 2.3.5-1-limethylphenol 20
Part (compound of Compound Specific Example No. 2, melting point 95°C) 5% aqueous solution of methylcellulose 20 parts water
60 parts [Liquid D] Urea-formalin resin fine powder 20 parts 5% methylcellulose aqueous solution 20 parts water
60 parts Next, 10 parts of liquid A, 30 parts of liquid N, 3 o parts of liquid C, 2 o 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. The dry adhesion amount is 4 to 5 on a high-quality paper of 50 g per tsubo Jt.
A heat-sensitive coloring layer was provided by coating and drying to give a ratio of g/r/, and then the layer surface was calendered to give a surface smoothness of 500 to 600 seconds to prepare a heat-sensitive recording material (j).

Comparative Example 7 Example 4 except that water was used instead of liquid (C) in Example 4.
A thermosensitive recording material (k) was prepared in the same manner as above.

Comparative Example 8 A heat-sensitive recording material (12) was prepared in the same manner as in Example 4, except that the following liquid (E) was used instead of liquid (C) in Example 4.

(E) Liquid stearamide 20 parts 5% aqueous solution of methylcellulose 20 parts water
60 copies or more of the heat-sensitive recording materials (j) to (Q) obtained as described above were printed using a heat-sensitive printing experimental device having a thin-film head manufactured by Matsushita Electronics Co., Ltd. at a head power of 0.45 V/dot and a recording time of 20 n+ per line.
sec/Q, pulse width 1.6.2.0.2.4 (+5 sec) under the conditions of scanning line density 8 x 3.85 dots/■
Macbeth Densitometer RD-514
(filter lt-106). The results are shown in Table-1.

Table-1 Next, heat-sensitive recording materials (j) to (Q) were tested using a thermal gradient tester (Toyo Seiki Il) at a pressure of 2 kg and a contact time of 1 second.
℃ conditions, cut out a 4 cm square with the printed area in the center, overlapped with a sheet of polyvinyl chloride film (Polywrap V-300 manufactured by Shin-Etsu Polymer ■), and applied a load of 500 at room temperature.
After applying g/c+J for 24 hours, take it out and measure the density of the background part and the density of the colored part using a Macbeth densitometer (RD-514).
and compared with the concentration before the test. The results are in Table-2
It is as follows.

Table 2 Next, when a thin layer of cottonseed oil was applied to the background and colored areas of the similarly printed samples and the samples were stored at room temperature for 24 hours, all samples (j) to (a) had the same coloration as the colored areas in the background area. No discoloration was observed.

Next, place a sample printed in the same way at a distance of 4 cm around the printed area.
100n+Q cut out on all sides and filled with 80m of tap water
The sample was immersed in a beaker at room temperature for 24 hours, taken out and dried, and the change in density of the colored area was measured. The results are shown in Table-3.

Table 3 From the above, the heat-sensitive recording material of the second invention has high sensitivity and white background, does not develop color on the background or decolorize the colored area even when in contact with oils or plasticizers, and is resistant to immersion in water. It can be seen that the image density does not decrease even when it comes into contact with water, such as by immersion, and is extremely practical.

Claims (2)

[Claims] (1) In a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and its color developer, the general formula (
I) ▲Mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R_2 is an alkyl group having 1 to 8 carbon atoms, R_
3, R_4, R_5 and R_6 are hydrogen atoms or have 1 carbon number
~8 alkyl group, provided that R_5 and R_6 are not hydrogen atoms at the same time. ) A heat-sensitive recording material characterized in that it uses a monophenol compound represented by: (2) In a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and its color developer, the color developer may be of the general formula (
II) (R)kZn(X)_2(II) (wherein, R represents an organic ligand capable of bonding with a zinc ion via a heteroatom to form a complex, k represents 2 or 4, X represents SCN or a halogen atom. represents an alkyl group of 1 to 8,
R_3, R_4, R_5 and R_6 represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, provided that R_5 and R_6 are not hydrogen atoms at the same time. ) A heat-sensitive recording material characterized in that it uses a monophenol compound represented by: