JPS60239281A - Thermal recording paper - Google Patents

Abstract

PURPOSE:To enhance color forming sensitivity and reduce ground density, by incorporating at least one fluoran compound of a specified general formula into a thermal recording paper as a color former. CONSTITUTION:A coating liquid comprising at least one fluoran compound of the formula, wherein R1 is 1-8C alkyl, cyclohexylalkyl, cycloalkyl or the like, R2 is hydrogen, halogen, 1-4C alkyl or the like, R3 is hydrogen, chlorine, fluorine or 1-4C alkyl, and A is branched 1-6C alkylene group, is applied to the base such as a paper, followed by drying to obtain the thermal recording paper. The fluoran compound is used in combination with a color developer such as 4-t- butylphenol.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal recording paper characterized by containing at least one type of novel fluoran compound as a color former (electron-donating coloring agent).

Thermal recording paper 4 is a recording paper with a structure in which a so-called thermosensitive coloring layer that develops color when heated is formed on a support such as paper, and a thermal printer with a built-in thermal head is used to heat the coloring layer. It is used. Compared to other types of recording paper, recording paper with a structure that has a heat-sensitive coloring layer is widely used in printers, etc. due to its advantages such as being cheaper, making less noise, and being able to record in a short time. It's being used. The most important thing for thermal recording paper is that it has excellent color development sensitivity, but recently it has also begun to be used for display labels for PO8 (point op sale), etc., and it is essential that the color image has a good shelf life. It has become a condition of

The minimum properties that should be possessed by the coloring layer of thermal recording paper are excellent self-coloring resistance (surface resistance), pressure coloring resistance, coloring sensitivity, moisture and coloring resistance, heat coloring resistance, oil resistance, and light resistance. However, currently we have not found anything that fully satisfies these requirements. Color formers that produce a black color are often used for heat-sensitive coloring waste, but fluoran compounds as color formers were developed in the Japanese Patent Publication No. 51-25.
No. 204, Special Publication No. 51-29180, Special Publication No. 56-5
No. 2759, JP-A-57-53562, JP-A-58-
It is disclosed in No. 7453 and U8P-56B1590. Regarding heat-sensitive recording paper using a color former, Japanese Patent Publications No. 4160/1986 and Japanese Patent Publication No. 44/1983
-5680 and Japanese Patent Publication No. 49-17748 are known.

The present inventors used known fluoran compounds as Color Four! - Thermal recording papers were manufactured according to the conventionally known method or the method described in each of the above-mentioned patent publications, and were tested in terms of the performance that should be provided as a thermal recording paper. , color development sensitivity, moisture decolorization resistance,
It had shortcomings in oil resistance, resistance to surface fogging, etc.

The inventors of the present invention have conducted extensive studies on thermal recording paper that has improved these drawbacks, and have discovered that the performance of the thermal recording paper can be pleasantly improved by using a specific fluoran compound.

That is, the present invention provides the following general formula (1), (wherein R is a linear or branched alkyl group having 1 to 8 carbon atoms, a cyclohexyl alkyl group, a cyclic alkyl group, a substitutable phenyl group, an alkoxy Alkyl group, substitutable benzyl group,
or represents a hydrogen atom, R2 represents a hydrogen atom, a halogen atom, a lower alkyl group having 1 to 4 carbon atoms, a substitutable phenyl group, a substitutable benzyl group, a lower alkoxy group, or a lower 1-rukoxyalkyl group, R3 represents a hydrogen atom, a chlorine atom, a fluorine atom, or a lower alkyl group having 1 to 4 carbon atoms, and A represents a branched alkylene group having 1 to 6 carbon atoms. The present invention relates to a heat-sensitive recording paper characterized in that it contains at least one of the novel full chloride compounds represented by the following as a color former.

The fluoran compound represented by the general formula (I) is almost colorless in itself, but has the property of rapidly developing color when exposed to an electron-accepting substance. Phenol rust conductors such as hisphenol A (p-1) 0xbenzoic acid benzyl ester (D organic carboxylic acid ester) develop a blackish color.

Representative examples of the novel fluoran compound represented by general formula (1), which is a color former used in the thermal recording paper of the present invention, are shown below. The hue indicates the hue when the color is developed on one layer of silica gel.

In order to synthesize the fluoran compound represented by the general formula (1), which has not yet been invented, the following steps are required: A diphenylamine derivative represented by the general formula (wherein R and A have the same meanings as defined above).

) in a condensing agent such as sulfuric acid, phosphoric acid, or boric acid.

Obtained by treatment in alkaline water. For example 2
-Anilino-3-methyl-6-N-(2-cyclohexylpropyl-(1))-N-ethyl-aminofluorane is synthesized as follows.

2-Hydroxy-4-N-[2
-cyclohexylpropyl-(1)) -N-ethyl-amino-2'-carboxy-benzophenone 2a5
After adding F and completely dissolving it while keeping it at about 25℃,
2-Methyl-4-methoxy-diphenylamine 11.7
Add F for 20 hours at 0-5℃, and then at 25-30℃ for 2 hours.
After reacting for 4 hours, 1/2 cup of ice water was added to the reaction mixture, and the precipitate was collected by filtration. Toluene 450m' for cake
After adding 340 tons of 10% aqueous sodium hydroxide solution and stirring under reflux for 2 hours, the toluene layer was separated and washed with water, and the toluene was distilled off by steam distillation. The precipitated crystals were collected by filtration, and after washing by adding 200 methanol to the cake, the crystals were collected again by filtration.

The crystals were dried to give a pale and colored 2-1nilino-3-methyl-b-N-(2-cyclohexylglobyl-(1))-
N-ethyl-aminofluorane 21.5F was obtained. The melting point of this fluoran compound is 187.5°C to 190°C.
It was 0°C. In addition, the λmax and molecular extinction coefficient of this compound in a 95% acetic acid solution are 455 nm (1,
924X10') and 597nm (2,02X104
)Met. A solution obtained by dissolving this product in toluene was colorless and quickly developed color due to bisphenol A, giving it a reddish-black color.

Color developers used in combination with these fluoran compounds include 4-1-butylphenol, 4-phenylphenol, and methyl-4-hydroxybenzoate.
a, at-isopropylidenediphenol, 4.4
'-Impropylidene bis(2,6-dibromophenol), bis(4-hydroxyphenyl)sulfone, p-
Conventionally known color developers include benzyl human mixybenzoate, 5ee-butyl p-hydroxybenzoate, and 3-(a-methylbenzyl)salicylic acid.

Furthermore, various water-soluble or water-insoluble binders are used in the heat-sensitive coloring layer of the present invention for binding onto the support. Typical examples include polyvinyl alcohol, methylcellulose, hydroxyethylcellulose,
calgeximethylcellulose, gum arabic, starch,
There are gelatin, casein, holivinylpyrrolidone, styrene-maleic anhydride copolymer, etc., but the binder that can be particularly preferably used in the present invention is a water-soluble binder, and a typical example is polyvinyl It's alcohol.

In addition, in the heat-sensitive coloring layer, if necessary, auxiliary additives such as fillers such as aluminum hydroxide, calcium carbonate, magnesia, barium sulfate, calcium stearate, dimethyl terephthalate, dibenzyl terephthalate, β-naphthol benzyl ether, etc. By adding conventionally known sensitivity improvers such as , stearamide, benzyl p-benzyloxybenzoate, etc., it is possible to improve the clarity or color density of colored stools.

The thermosensitive recording paper of the present invention is produced by applying and drying a coating liquid for forming a thermosensitive coloring layer containing the above-mentioned components onto a support such as paper. The heat-sensitive recording paper of the present invention thus obtained had characteristics such as excellent color development sensitivity and low background density (less background capri). The performance of the thermal recording paper was determined by the following test method. That is, the skin density was measured using a Macbeth RD-514 reflection densitometer. Heating coloring was done using Rhodiaceta type Thermotest Test A (manufactured by France National Textile Research Institute), heating temperature 60-170℃, heating time 3 seconds, load 10 ot/cd.
It was conducted under the following conditions.

Next, the present invention will be explained in detail with reference to Examples.

Example 1 Mixtures having the following compositions were separately ground for 3 hours using a paint conditioner (trade name: Red Devil) to prepare liquids (1), (2), and (2).

■Liquid composition 2-1 Nilino 3-methyl-6-N-(2-cyclohexylpropyl-(1))-N-ethyl-1 Minofluorane 4 parts by weight 10% polyvinyl alcohol aqueous solution 34 parts by weight 5% antifoaming agent (Sannoguco 1407, San Nopco product) 2 parts by weight ■Liquid composition Bisphenol A 6 parts by weight 10% polyvinyl alcohol aqueous solution 20 parts by weight Water
14 parts by weight ◎Liquid composition Aluminum hydroxide 10 parts by weight 10% polyvinyl alcohol aqueous solution 20 parts Water 1
0 parts by weight Solution (■), Solution (■), Solution (◎) and water were mixed in a weight ratio of 5:9:5:5 to obtain a paint for heat-sensitive recording paper. This paint was applied to the surface of high-quality paper using a wire bar until the solid weight after drying was 5.
f/rr? The coated paper was coated so as to have the following properties, placed in a blow dryer, and dried at room temperature to obtain the thermal recording paper 0) of the present invention.

Comparative Example 1 A comparative thermosensitive recording paper (→ was obtained in exactly the same manner as in Example 1, except that liquid O was used instead of liquid ①).

[F] Liquid composition 2-1 Nilino 3-methyl-6-N-methyl-N-cyclohexyl-amino-fluorane 4 parts by weight 10% polyvinyl alcohol aqueous solution 34 parts 5% Antifoaming agent (San Nopco 1407) 2 parts by weight The heat-sensitive recording papers of the present invention and comparative heat-sensitive recording papers obtained as described above were tested for coloring sensitivity and background capri. The results are shown in Table 1.

Example 2 2-anilino-3-methyl-6-N used in Example 1
-(2-Cyclohexylpropyl-(1)]-]Thermal recording paper (B) was prepared in the same manner as in Example 1, using the fluoran shown in Table 1 instead of N-ethylaminofluora.
~(b) was obtained. Performance tests on these thermal recording papers of the present invention were carried out in the same manner as in Example 1. The results are shown in Table IK.

The thermal recording papers 0) to (b) of the present invention have extremely excellent color development sensitivity and low background depth, and have sufficient practical value as thermal recording papers for various recording fields, especially for high-speed recording. was there.

Hodogaya Chemical Industry Co., Ltd.

Claims (1)

[Scope of Claims] General formula (wherein R1 is a linear or branched alkyl group having 1 to 8 carbon atoms, a cyclohexylalkyl group, a cyclic alkyl group, W
R2 represents a substitutable phenyl group, an alkoxyalkyl group, a substitutable benzyl group, or a hydrogen atom, and R2 is a hydrogen atom, a halogen atom, a lower alkyl group having 1 to 4 carbon atoms, a substitutable phenyl group, a substitutable benzyl group. s represents a group, a lower alkoxy group, or a lower alkoxyalkyl group.
R1 represents a hydrogen atom, a chlorine atom, a fluorine atom, or a lower alkyl group having 1 to 4 carbon atoms, and A represents a branched 1-rukylene group having 1 to 6 carbon atoms. 1. A heat-sensitive recording paper containing at least one of the novel fluoran compounds represented by the following as a color former.