JP2001287461A - Heat sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat sensitive recording material excellent in the color developing speed, color development density and storage stability of a recorded image. SOLUTION: In the heat sensitive recording material utilizing the color development reaction between an electron donable leuco dye and an electron acceptable developer, which develops color in the dye, a heat sensitive recording layer includes an acyl anilide-based compound represented with general formula (1) and an diphenoxy ethane-based compound represented with general formula (2), wherein R represents a methyl group or an ethyl group, X represents a hydrogen atom, a methyl group, an ethyl group, a chlorine atom or a bromine atom, R1 and R2 each represent hydrogen atoms, methyl groups or methoxy groups, which are same as each other or different from each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material, and more particularly, to a heat-sensitive recording material utilizing a color-forming reaction between an electron-donating leuco dye and an electron-accepting developer for forming the dye.

[0002]

2. Description of the Related Art Thermosensitive recording materials are known as recording materials utilizing a color-forming reaction between an electron-donating leuco dye represented by crystal violet lactone, a fluorene-based or fluoran-based leuco dye, and an electron-accepting developer. Widely used. In the heat-sensitive recording material, when the leuco dye and the developer are melted and mixed by heat to form a color, the amount of applied heat energy is small, and the color-forming speed is high, and the color density is required to be high, Various proposals have been made to address this. For example, a method of adding a third substance called a sensitizer or a solubilizer for the purpose of improving the color development speed has been proposed and put into practical use.

[0003] Such sensitizers include acetylanilide, acetyltoluidide, stearoylamide, 2-acetyl amide.
Benzyloxynaphthalene, 1,2-bisphenoxyethane, 1,2-bis (3-methylphenoxy) ethane,
1- (2-methylphenoxy) -2- (4-methoxyphenoxy) ethane, 4-benzylbiphenyl, 4-toluoxybiphenyl, bis (4-methylbenzyl) oxalate and the like are disclosed (JP-B-43-4160). JP, JP-A-59-9092, JP-A-58-87
094, JP-A-60-56588, JP-A-60-82382, JP-A-64-1583 and JP-A-2-9683.

[0004]

However, in the prior art, the improvement of the coloring speed and the coloring density and the storage stability, especially the stability of the color image at high temperatures (heat resistance, moisture resistance, oil resistance It is desired to improve the oiliness and plasticizer resistance) and the whiteness of the uncolored portion (stain on the background). This requirement is particularly large when 4,4'-bis (4-hydroxyphenyl) sulfone (bisphenol S) is used as a developer.

An object of the present invention is to provide a heat-sensitive recording material which is excellent in the color development speed, color density and storage stability of a recorded image.

[0006]

According to the present invention, there is provided a heat-sensitive recording material utilizing a color-forming reaction between an electron-donating leuco dye and an electron-accepting color developer for forming the dye. 1)

[0007]

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(In the formula, R represents a methyl group or an ethyl group, and X represents a hydrogen atom, a methyl group, an ethyl group, a chlorine atom or a bromine atom.)

An acylanilide compound represented by the general formula (2)

[0010]

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(In the formula, R ¹ and R ² are the same or different and each represent a hydrogen atom, a methyl group or a methoxyl group.)

And a diphenoxyethane-based compound represented by formula (1).

[0013]

Embodiments of the present invention will be described below in detail.

As the acylanilide compound represented by the general formula (1), acetanilide, 2-, 3- or 4-
Examples thereof include chloroacetanilide, 2-, 3- or 4-acetotoluizide, propioanilide, and 2-, 3- or 4-propiotoluizide, and preferably 4-acetotoluizide.

The diphenoxyethane compounds represented by the general formula (2) include 1,2-bis (phenoxy) ethane, 1,2-bis (2-methylphenoxy) ethane,
1,2-bis (3-methylphenoxy) ethane, 1,2
-Bis (4-methylphenoxy) ethane and 1- (2-
Methyl) -2- (4-methoxyphenoxy) ethane and the like are exemplified, and 1,2-bis (phenoxy) ethane and 1,2-bis (3-methylphenoxy) ethane are preferable, and in particular, 1,2-bis (3-Methylphenoxy) ethane is preferred.

The sensitizers may be mixed in a required ratio by finely dispersing each in an aqueous medium, or
Alternatively, a method of finely dispersing a mixture obtained by mixing the respective powders in a required ratio in an aqueous medium, or a method of mixing and cooling the respective powders at a predetermined ratio and then pulverizing the resulting mixture in an aqueous medium is used. Is taken. The mixing ratio is 20:
80-80: 20 is preferable, and especially 30: 70-7.
0:30 is preferred.

Examples of the electron-donating leuco dye include crystal violet lactone, 3,3'-bis (4-dimethylaminophenyl) phthalide, and 3- (4-dimethylaminophenyl) -3- (1,2-dimethylaminoindole. -3-yl) phthalide, 3-methyl-3-spirodinaphthopyran, 2-anilino-3-methyl-6-diethylaminofluoran, 2-anilino-3-methyl-6-dibutylaminofluoran and 2-anilino Examples thereof include -3-methyl-6- (4-toluidinoethylamino) fluoran and the like.

Examples of the electron-accepting color developer include 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 4,4'-bis (4-hydroxyphenyl) sulfone (bisphenol S), (Hydroxyphenyl)-(4-hydroxyphenyl) sulfone, bis (4
-Hydroxy-3-methylphenyl) sulfone, bis (4-hydroxy-3-allylphenyl) sulfone, 4
Examples thereof include -hydroxy-4'-isopropoxydiphenyl sulfone and {2- (4-hydroxyphenoxy) ethyl} ether, and the effect is remarkable in 4,4'-bis (4-hydroxyphenyl) sulfone. .

These leuco dyes, developers and sensitizers are usually pulverized in an aqueous medium containing a dispersant or the like by a pulverizer such as a ball mill, a colloid mill, a high-pressure homogenizer or a sand grinder, and then mixed. It is prepared by adding a filler such as calcium carbonate, a lubricant such as wax, a water-soluble adhesive, an antifoaming agent, etc. to prepare a paint, and coating and drying on a support such as paper, film and synthetic paper. Finish on thermal recording paper.

[0020]

EXAMPLES In order to further clarify the present invention, examples and comparative examples are shown below (the amounts used are shown in parts by weight unless otherwise specified).

(Example 1) <Preparation of solution A> 10 parts of 2-anilino-3-methyl-6-dibutylaminofluorane 10 parts of 4-acetotoluizide 10 parts of 1,2-bis (3-methylphenoxy) ethane Cellulose 5% aqueous solution 15 parts Water 120 parts

This composition was pulverized with a sand grinder to an average particle diameter of 1 μm to obtain a liquid A.

<Preparation of Solution B> 4,4'-bis (4-hydroxyphenyl) sulfone 20 parts Methyl cellulose 5% aqueous solution 30 parts Water 70 parts

This composition was pulverized with a sand grinder to an average particle diameter of 1 μm to obtain a liquid B.

<Preparation of heat-sensitive recording material by forming recording layer> 175 parts of solution A, 130 parts of solution B, calcium carbonate pigment 2
0 parts, zinc stearate 5 parts, 20% oxidized starch aqueous solution 1
50 parts and 55 parts of water were mixed to prepare a coating solution. 50g
/ M ² of base paper having a coating amount of 4 g /
m ² to obtain a thermosensitive recording paper.

(Example 2) 1,
A thermosensitive recording paper was obtained in the same manner as in Example 1, except that 10 parts of 1,2-bis (phenoxy) ethane was used instead of 10 parts of 2-bis (3-methylphenoxy) ethane.

Comparative Example 1 Except that 20 parts of 4-acetotoluzide was used instead of the mixture of 10 parts of 4-acetotoluide and 10 parts of 1,2-bis (3-methylphenoxy) ethane in Example 1. The same operation as in Example 1 was performed to obtain a thermosensitive recording paper.

Comparative Example 2 Instead of the mixture of 10 parts of 4-acetotoluizide and 10 parts of 1,2-bis (3-methylphenoxy) ethane in Example 1, 1,2-bis (3-methylphenoxy) A thermal recording paper was obtained in the same manner as in Example 1, except that 20 parts of ethane were used.

<< Evaluation of Examples and Comparative Examples >><Evaluation 1: Evaluation of Coloring Sensitivity (Coloring Speed)> The thermosensitive recording papers obtained in Examples 1, 2 and Comparative Examples 1 and 2 were heat-sensitive. Using a printing device {manufactured by Okura Electric Co., Ltd.}, a printing voltage of 24 V, a printing cycle of 8 milliseconds, a pulse width of 0.0 and a.
7, 0.8, 1.0, 1.2, 1.4, 1.6 and 2.
Printing was developed in eight stages of 0, and the color development density was measured with a Macbeth densitometer (manufactured by Sakata Inx Co., Ltd.) to compare the color development sensitivities.

<Evaluation 2: Evaluation of heat resistance> The recording paper obtained in Evaluation 1 was left in an electric oven having an internal volume of about 200 liters at 60 ° C. for 16 hours, and the degree of fading of the recorded image and the rash of the uncolored portion were observed. Was visually evaluated by the following evaluation method.

Evaluation level A: sufficiently good. ：: good. □: Partial failure and practical limit. ×: Poor for practical use.

<Evaluation 3: Evaluation of Moisture Resistance> The recording paper obtained in Evaluation 1 was left in a device maintained at 45 ° C./90% RH for 16 hours, and evaluated by the same evaluation method as Evaluation 2. did.

<Evaluation 4: Evaluation of Plasticizer Resistance> The recording paper obtained in Evaluation 1 was sandwiched between upper and lower double wraps with a plastic wrap film made of polyvinyl chloride containing a plasticizer, and 20 g / g
After placing the weight of ² cm ² and leaving it at 20 ° C for 24 hours,
Evaluation was performed by the same evaluation method as Evaluation 2.

Table 1 shows the results.

[0035]

[Table 1]

[0036]

As is clear from Table 1, the heat-sensitive recording material according to the present invention is excellent in the recording color-forming speed, the color-forming density, the preservability of the color-formed image and the uncolored part, The fact that 4,4′-bis (4-hydroxyphenyl) sulfone (bisphenol S), which had a problem in color density, can be advantageously used has great industrial significance.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Takashi Ishibashi 1-10-24, Itokaichi, Ibaraki-shi, Osaka F-term in Sanko Development Research Institute Co., Ltd. (Reference) 2H026 AA07 BB01 BB30 DD02 DD12 DD45 DD53 FF01

Claims (5)

[Claims] 1. A heat-sensitive recording material utilizing a color-forming reaction between an electron-donating leuco dye and an electron-accepting color developer for forming the dye, the heat-sensitive recording layer comprising a compound represented by the general formula (1): (Wherein, R represents a methyl group or an ethyl group, and X represents a hydrogen atom, a methyl group, an ethyl group, a chlorine atom or a bromine atom), and an acylanilide-based compound represented by the general formula (2): ] (Wherein R ¹ and R ² are the same or different and each represent a hydrogen atom, a methyl group or a methoxy group), and a diphenoxyethane-based compound represented by the following formula: 2. The heat-sensitive recording material according to claim 1, wherein the acylanilide-based compound represented by the general formula (1) is 4-acetotoluidide. 3. The diphenoxyethane compound represented by the general formula (2) is 1,2-bis (phenoxy) ethane or 1,2-bis (phenoxy) ethane.
The heat-sensitive recording material according to claim 1, which is 2-bis (3-methylphenoxy) ethane. 4. An acylanilide compound represented by the general formula (1) is 4-acetotoluidide, and a diphenoxyethane compound represented by the general formula (2) is 1,2.
The heat-sensitive recording material according to any one of claims 1 to 3, which is 2-bis (3-methylphenoxy) ethane. 5. The method according to claim 1, wherein the electron-accepting developer is 4,4′-bis (4
The heat-sensitive recording material according to claim 1, which is -hydroxyphenyl) sulfone.