JPS5939594A - Heat sensitive recording paper - Google Patents

Abstract

PURPOSE:To obtain a heat sensitive recording paper with an improved color formation sensitivity excellent in the heated water resisance and water resistance by arranging a specified benzenesulfonic amide compound into a recording layer. CONSTITUTION:A fluorane compound, colorless or slightly light-colored fluorane compound (e.g. 2-(2-chlorophenyl amine)-6-diethylamine-fluorane), an acid substance (e.g. bisphenol A) for having said fluorane compound forming color when heated, a binder (e.g. PVA) and one or more kinds of benzenesulfonic amide compounds of the formula (R1 is lower alkyl or acetylamine, R2 H or lower alkyl, R3 lower alkyl or substitutable phenyl, R2 and R3 may each form a saturated ring with N) are applied on a support such as paper as water slurry to obtain a desired heat sensitive paper.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal recording paper, and more particularly to a thermal recording paper that has excellent heat resistance and water resistance, and has improved heat-sensitive characteristics, and in particular, it relates to a thermal recording paper that has improved color development sensitivity. It relates to thermal recording paper.

The minimum performance required for a recording layer of thermal recording paper is excellent self-coloring resistance, pressure coloring resistance, heat sensitivity, light resistance, heat decoloring resistance, moisture decoloring resistance, and water resistance. However, we have not yet obtained anything that completely satisfies these requirements.

First, as a method of improving self-coloring resistance,
8-101943 (Japanese Patent Publication No. 51-29850) describes the addition of a water-soluble alkanolamine compound, and JP-A-49-11141 (Japanese Patent Publication No. 51-2825) describes the addition of a basic organic compound. ing.

As a method to improve water resistance, Japanese Patent Application Laid-Open No. 49-3643
No., JP-A-49-52646, JP-A-50-3055
No. 9, JP-A-52-145228 and JP-A-55-
No. 15929 describes the use of a water-soluble binder and a water-resistant agent in combination.

As a method for improving colorfastness, Japanese Patent Application Laid-Open No. 48-52
245, a phenol resin which is a condensation product of a phenol compound and an aliphatic aldehyde or an alkyl vinyl ether, and 4.4'-thiobis(6
JP-A No. 55-17347 describes the addition of water-insoluble modified phenol resins such as rosin-modified or terpene-modified resins. ing.

In addition, as a method for improving heat-sensitive characteristics,
7748 and Japanese Patent Publication No. 51-39567, the use of an organic acid and a phenolic compound as acidic substances in combination;
Alternatively, it is described that a polyvalent metal salt of a compound having an alcoholic hydroxyl group is used. Japanese Patent Publication No. 49-1114
No. 0 (Japanese Patent Publication No. 51-29945) describes the use of a copolymer of K hydroxyethyl cellulose and maleic anhydride. Furthermore, JP-A-49-34842, JP-A-49-115554, JP-A-50-1495
No. 55, JP-A-52-106746, JP-A-53-5
No. 636, JP-A-53-11036, and JP-A-5
! 1-48751 etc., thioacetanilide, phthalonitrile, acetamide, di-β-naphthyl-p-phenylenediamine, fatty acid amide, acetoacetanilide,
Nitrogen-containing organic compounds such as diphenylamine, penzamide, carbazole, etc. or thermofusible substances such as 2,3-di-m-)lylbutane, 4,4'-dimethylbiphenyl, or dimethyl isophthalate, diphenyl phthalate, etc. The addition of calgenic acid esters such as esters as sensitizers is described.

The present inventors manufactured thermal recording paper using a known fluoran compound as a coloring agent and according to the methods described in the above-mentioned patent publications and the methods described in the above-mentioned patent publications. 3- When tested on the surface, the initial color development temperature by heating (
Ts) is high, and the rising temperature coefficient D of the color density curve is high.
) was low, and the maximum color density (Dmax) was low, indicating poor thermal properties. For this reason, it is not practical as a thermal recording paper for facsimile 1, especially high-speed facsimile. In addition, thermally colored recording paper is 50 to 6
When the sample was left in an atmosphere at 0° C. and 20% relative humidity for 3 to 5 days, the concentration of the color former decreased compared to that immediately after color development. That is, the heat decolorization resistance is low. Sg)K
12 in an atmosphere of 50-60℃ and relative humidity 80-90%.
When left for ~24 hours, the concentration of the color former becomes lower than the color density immediately after the color development, and in some cases the color disappears completely, with no trace of the color former being even visible. In other words, the moisture decoloring resistance is low. When thermal recording paper that uses a water-soluble binder as a binder or thermal recording paper that has been colored by heating is immersed in water for a long time, both the uncolored thermal recording layer and the colored thermal recording layer will flow. , or faded. In other words, water resistance is poor.

41 The present inventors have completed the present invention as a result of intensive research in order to improve the above-mentioned drawbacks of heat-sensitive recording paper using known fluoran compounds.

That is, the present invention provides a heat-sensitive recording paper comprising, on a support, a recording layer basically comprising a colorless or slightly pale fluoran compound, an acidic substance that causes the fluoran compound to develop color when heated, and a binder. The bait recording layer contains the following general formula, (wherein R1 is a lower alkyl group or an acetylamino group, R2 is a hydrogen atom or a lower alkyl group,
R3 is a lower alkyl group or a substitutable phenyl group. Further, R2 and Rs may form a saturated ring together with N. ) A thermosensitive recording medium characterized by containing one or more benzenesulfonamide compounds represented by:

Conobenzenesulfonamide compound is a white crystal synthesized from benzenesulfonyl chloride and amine and is difficult to dissolve in water.

The normally colorless or light-colored fluoran compound used in the thermal recording paper of the present invention can be selected from a large number of conventionally known fluoran compounds. Formula (in the formula, R4 is a lower alkyl group, R5 is a lower alkyl group, a cyclohexyl group, or an optionally substituted phenyl group, and R4 and R11 may form a heterocycle together with the nitrogen atom to which they are bonded) , X is a hydrogen atom or a lower alkyl group, and Y is a hydrogen atom, a lower alkyl group, ).rogen atom or a trifluoromethyl group. )
This is a conventionally known compound represented by The representative compounds are listed below.

7- 2-(2-chlorophenylamino)-6-dinithylaminofluorane, 2-(2-chlorophenylamino)-6
-D-n-butylaminofluorane, 2-anilino-3
-Methyl-6-dinithylaminofluorane, 2-1nilino-3-methyl-6-pyrrolidinylfluorane, 2-anilino-3-methyl-6-piperidinofluorane, 2-
(3-Trifluoromethylanilino)-6-dinithylaminofluorane, 2-anilino-6-dinithylaminofluorane, 2-anilino-3-methyl-6-(N-ethyl-N-p-) lyl)aminofluorane, 2-(p-ethoxyanilino)-3-methyl-6-dinithylaminofluorane, 2-xylidino-3-methyl-6-dinithylaminofluorane, 2-anilino-5- Methyl-6-(N
-Methyl-N-cyclohexylamino) fluorane, but is not limited to these fluoran compounds.

The acidic substance used in the present invention is a substance that is solid at room temperature and can react with a color forming agent when heated, and a representative example thereof is a phenolic compound described in Japanese Patent Publication No. 14039/1983. Or 50℃ such as stearic acid, benzoic acid, gallic acid, salicylic acid etc.
These are colorless solid organic acids or their metal salts such as aluminum and zinc, which have the property of liquefying or vaporizing. Acidic substances that can be suitably used are the above-mentioned phenolic compounds, a typical example of which is 4,4'-impropylidene diphenol (bisphenol A) theal.

Next, representative examples of the benzenesulfonamide compound represented by the general formula (1) (hereinafter referred to as an additive compound) according to the present invention are shown in Table I, but these representative examples are not intended to limit the present invention.

Table I A water-soluble or water-insoluble binder is used as the binder for binding the mixture of color former, acidic substance, and additive compound onto the support sheet. Typical examples include polyvinyl alcohol, methylcellulose, droxyethylcellulose, calgeximethylcellulose, gum arabic, marten flour, gelatin, casein, polyvinylpyrrolidone, styrene-maleic anhydride copolymer, polyacrylic acid amide, and polyacrylic. Although there are acid salts, terpene resins, and petroleum resins, the binder particularly preferably used in the present invention is a water-soluble binder, and a typical example thereof is polyvinyl alcohol ether.

In order to produce the thermal recording paper of the present invention, each component consisting of a fluoran compound as a coloring agent, an acidic substance, and one or more additive compounds represented by the general formula [■] is formed into fine particles. Although it is preferable in terms of the performance of thermal recording paper to provide a layer that exists in a uniform state in one heat-sensitive layer, it is also preferable that each component consisting of a coloring agent and an additive compound be formed as fine particles in a single layer. A method of providing a layer in which fine particles of an acidic substance exist in a uniform state by adhering to this layer, or a method in which each component consisting of an acidic substance and an additive compound is present as fine particles in one layer. A method of providing a layer in which fine particles of a coloring agent are present in a uniform state by adhering to this layer; There is a method in which layers existing in a uniform state are brought into close contact with each other.

When producing the heat-sensitive recording paper of the present invention, the weight ratio of each of the above-mentioned components and binder in the recording layer to the coloring agent is 0.0.
1 to 10 times, preferably rl, 3 to 3 times, the acidic substance is 2 to 10 times, preferably 4 to 6 times, and the binder is α3 to 3 times, preferably [L5 to 1 times]. be.

The color former, acidic substance and additive compound are preferably each separately dispersed in a dispersing machine such as a ball mill, sand mill or paint conditioner in water or an organic medium containing a binder, preferably in which the binder is dissolved. It is dispersed in water as a medium and pulverized to form a suspension with a particle size of 1 to 6 microns, preferably 3 to 5 microns. If necessary, an antifoaming agent, dispersant, or brightener may be added for dispersion and pulverization.

Next, a suspension of each of the above-mentioned separately dispersed and pulverized components is mixed to form a paint for forming a heat-sensitive recording layer, when the weight ratio of each component in the recording layer is as described above. .Apply this paint to the surface of the paper by wire paring +6~+
10, the weight of the solid after drying is 3 to 7 F/77
A heat-sensitive recording paper is produced by coating the film at a temperature of 1' and drying it in a blow dryer at room temperature to 70°C. If necessary, an inorganic or organic filler may be added to the paint to improve the thermal head's fusion resistance, binding properties, etc.

The thermal recording paper of the present invention was obtained through such efforts.

It has excellent heat-sensitive properties, heat decoloring resistance, moisture decoloring resistance, and water resistance, and successfully overcomes the drawbacks of conventionally known thermal recording papers.

The performance of the recording layer of the thermosensitive recording paper was tested using the following test method. In other words, the color density of the self-developed color, the color density after heat color development at each temperature, and the decolorization density of the color former in hot air or humidity after heat color development is measured using a Macbeth RD-514 reflection densitometer. Measured using The heating temperature was 80 to 170 using a Rhodiaceta type thermotest tester (manufactured by the French National Textile Research Institute) for color development.
℃, heating time for 3 seconds, and a load of 100 P/-. Further, decoloring of the coloring agent after coloring by heating was carried out using a constant temperature and humidity tester.

The present invention will be specifically explained below using examples, but the present invention is not limited to these examples.

Example Solution B (Developer Dispersion) Solution C (Additive Compound Dispersion) The canned liquid of the above composition is ground to a particle size of 2 to 3 microns using a ball mill.

Next, each dispersion liquid is mixed in the following proportions to form a paint.

Furthermore, as a control, liquids A and B were mixed in the following proportions to prepare a paint.

15- Apply these paints to the surface of high-quality paper using a Φ1o wire bar coater, and the solid weight after drying is 5 Pan? I applied it so that it looked like this and put it in a blow dryer to dry it. Regarding the obtained thermal recording paper, those of the present invention are (a) to (y),
Table H shows the results of performance tests of each thermal recording paper, with the control being shown as (Yu).

16- Note; *1; Background and color density were measured with a Macbeth reflection densitometer RD-514 model using a biscore filter. The heating color development conditions were 150° C., 3 seconds, and a load of 100 tons.

*2; Humid heat storage conditions are 60°C, 80% RH, and 24 hours.

*3; Light irradiation conditions were determined using a carbon arc lamp light resistance tester [6
It's time.

*4; The first value is the value when the color is developed after being stored under the conditions described above (see *2 and *3) in an uncolored state.
The value in parentheses is the reflection density after storage in a colored state.

*5; Tanθ at the maximum slope of the color density-color temperature curve, where the vertical axis is the color density and the horizontal axis is the color temperature, is 10.
The value multiplied by 0 is γ, which is a measure of the rise of color development. Also, the intersection of the tangent at the maximum inclination and the temperature axis is Ts
and indicates the temperature at which color development starts. In addition, heating color development was performed using a Rhodiaceter type thermotest tester (manufactured by the French National Textile Research Institute) at a heating temperature of 70 to 160°C and a heating time of 5 seconds.
The test was carried out under the condition of a load of 1007P/-.

As is clear from Table 2, the thermal recording paper (
A) to (Y) are compared with the control thermal recording paper (evening).
The color density is high, and the color development sensitivity is particularly improved.

Hodogaya Chemical Industry Co., Ltd.

Claims (1)

[Scope of Claims] A thermal recording paper comprising a recording layer provided on a support, which basically includes a colorless or slightly pale fluoran compound, an acidic substance that causes the fluoran compound to develop color when heated, and a binder. , the bait recording layer contains the following general formula (wherein R1 is a lower alkyl group or an acetylamino group, R2 is a hydrogen atom or a lower alkyl group,
R3 is a lower alkyl group or a substitutable phenyl group. Further, R2 and R3 may form a saturated ring together with N. ) A thermosensitive recording paper characterized by containing one or more benzenesulfonamide compounds represented by: