JPS62294585A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material imparting sufficient developed color density, having sufficient color forming sensitivity, suitable for high speed recording and reduced in background fog at the time of preservation, in a thermal recording material utilizing color forming reaction between a leuco dye and the coupler thereof, by containing a nitrophenol compound represented by a specific formula as an auxiliary component. CONSTITUTION:In a thermal recording material utilizing the color forming reaction between a leuco dye and a coupler, a nitrophenol compound represented by general formula (I) (wherein X is a saturated or unsaturated hydrocarbon group, an alkoxy group, an acyl group or aq halogen atom and n is an integer of 1-4) is together used as an auxiliary component. This nitrophenol compound has high capacity melting the coupler and the leuco dye widely used at the time of heating and, by regulating m.p. of the nitrophenol compound used, the thermal recording material having arbitrary sensitivity can be obtained. Further, said compound pref. has m.p. of 40-150 deg.C and especially pref. has m.p. of 5-120 deg.C from the aspect of the storage stability and sensitivity of the thermal recording material. The proper use quantities of the leuco dye, the coupler and the color forming sensitivity enhancer are respectively 5-40wt%, 20-60wt% and 20-60wt%.

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 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, it cannot be said that the heat-sensitive recording materials produced based on these methods are sufficient in terms of color density, color sensitivity, background whiteness, etc.

〔the purpose〕

The purpose of the present invention is to provide sufficient color density and sensitivity.

Suitable for high-speed recording, and has less background fog during storage.
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 nitrophenol 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 formula, X is a saturated or unsaturated hydrocarbon group.

Represents an alkoxy group, acyl group or halogen atom, n
represents an integer from 1 to 4. ) The nitrophenol compound represented by the general formula (1) used as an auxiliary component in the present invention is a widely used color developer (electron-accepting compound) and leuco dye (electron-donating colorless dye) that is heated. By adjusting the melting point of the nitrophenol compound used, a heat-sensitive recording material of any sensitivity can be obtained.

The nitrophenol compound used in the present invention has a melting point of 40 to 15, from the viewpoint of storage stability and sensitivity as a heat-sensitive recording material.
A temperature of 0°C is preferable, and a temperature of 50 to 120°C is particularly preferable. Specific examples of the nitrophenol compound of the present invention are shown below, but the present invention is not limited thereto.

Compound NO Structural Formula 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. .

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=chlorphthalide, 3.3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6- Chlorfluorane, 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-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-(0- 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-3'-methoxy-benzoindolino-pyrylospirane, 3-(2'- Hydroxy-47-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)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, 2-
Chloro-3-(N-methyltoluidino)-7-(p-〇-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'-isopropylidenebis(2-chlorophenol), 2.2'-methylenebis(4-methyl-6-tert-butylphenol), 2.2'-methylenebis(4-ethyl-6-tert-butylphenol) , 4.4'-butylidene bis(6-tertbutyl-2
methyl)phenol, 4.4'-thiobis(6-tartbutyl-2-methyl)phenol, 4.4'-diphenolsulfone, 4.4'-diphenol sulfoxide, P-hydroxybenzoic acid Isopropyl.

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(111-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, the leuco dye, color developer, and auxiliary components are bonded and supported on a support.

Various conventional binders can be used as appropriate, for example,
Polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, sodium polyacrylate,
Polyvinylpyrrolidone, acrylic amide/acrylic ester copolymer, acrylic amide/acrylic ester/methacrylic acid ternary copolymer, styrene/maleic anhydride copolymer alkali salt, inbutylene/maleic anhydride copolymer In addition to water-soluble polymers such as alkali salts, polyacrylamide, sodium alginate, gelatin, and casein, polyvinyl acetate, polyurethane, styrene/butadiene copolymer, polyacrylic acid, polyacrylic acid ester, vinyl chloride/vinyl acetate copolymer Coalescence, polybutyl methacrylate, ethylene/vinyl acetate copolymer, styrene/
Latexes such as butadiene/acrylic copolymers 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 coating liquid 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 coated liquid. In this case, the amounts of the leuco dye, color developer, and coloring sensitivity enhancer used are 5 to 40% by weight and 20 to 40% by weight, respectively.
Appropriate amounts are 60% by weight and 20 to 60% by weight.

〔effect〕

The heat-sensitive recording material of the present invention has improved sensitivity, is suitable for high-speed recording, and has little background fog during storage, 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 [Liquid A] 10% 201I aqueous solution of 3-(N-methyl-N-cyclohexyl 20 parts amino)-6-methyl-7-anilite fluoran hydroxyethyl cellulose
60I/CB liquid] Bisphenol A 20 parts 10% of hydroxyethyl cellulose 20II aqueous solution water
5Qn [Liquid C] 2-nitro-4-chlorophenol 20 parts (compound of specific compound example No. 9, melting point 88°C) polyvinyl alcohol 10% aqueous solution 201I water
60〃[D
Liquid] Calcium carbonate 20 parts Methyl cellulose 5% aqueous solution 20 parts Water
6Q
Next, add AtElo part, 30 parts of liquid B, 30 parts of liquid C, 2 parts of liquid D.
0 parts and 20 parts of isobutylene-maleic anhydride copolymer
% alkaline aqueous solution to form a thermosensitive coloring layer forming solution, this was coated on high-quality paper with a basis weight of 50 g/rn' to a dry adhesion weight of 4 to 5 g/rn' and dried to form a thermosensitive coloring layer. After providing, the surface smoothness is further improved to 500 to 600.
A heat-sensitive recording material (a) was prepared by calendering the surface of the layer to a temperature of 10 seconds.

Example 2 A heat-sensitive recording material (b) was prepared in the same manner as in Example 1 except that the following CH3 liquid was used instead of the liquid (B) in Example 1.
It was created.

[E) Liquid p-hydroxybenzoic acid benzyl ester 20 parts 10% aqueous solution of hydroxyethylcellulose 20 parts water
60I
I Example 3 A heat-sensitive 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 parts 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 (a) 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 (G) was used instead of liquid [C) in Example 1.

[G] Liquid stearamide 20 parts 5% aqueous solution of methylcellulose 20n water
601I
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 the liquid (C) in Example 3.

The heat-sensitive recording materials (a) to (i) obtained as described above are
The pulse width was set to 1.5 mm using a thermal printing experimental device equipped with a thin film head made of sold-out electronic components, under conditions of head power of 0.45 W/dot, 1 line recording time of 20 m5 ec/Q, and scanning line density of 8 x 3.85 dots/mm. 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 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 present invention has high color development sensitivity, is suitable for high-speed v2 recording, and has little background fog during storage, 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, auxiliary components include general formulas, ▲mathematical formulas, chemical formulas, tables, etc.▼ (where X is saturated or unsaturated. represents a hydrocarbon group, alkoxy group, acyl group or halogen atom, and n is 1 to 4
A heat-sensitive recording material characterized by containing a nitrophenol compound represented by (representing an integer of ).