JPH06247052A - Heat sensitive recording body - Google Patents

Abstract

PURPOSE:To provide a heat sensitive recording body which is hard to generate texture fog under high temperature environment and has high sensitivity. CONSTITUTION:In a heat sensitive recording body, at least one kind to be selected out of 3-dimethylamino-7-(o-chlorophenyl amino) fluorane, and 3-diethyl amino-7-(m-trifluoromethl anilino) fluorane is used as basic dyes. At least one kind out of 4-hydroxydiphenyl sulfone compounds having the melting point of at least 120 deg.C is used as a coloration agent and emulsion of stearic amide having a mean particle diameter of not exceeding 0.5mum is used together.

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 high-sensitivity heat-sensitive recording material excellent in background fog in a high temperature environment.

[0002]

2. Description of the Related Art Heretofore, a heat-sensitive recording material has been well known, which utilizes a color reaction between a colorless or light-colored basic dye and a color-forming agent to react both color-forming substances with heat to obtain a recorded image. ing. Such a thermosensitive recording medium is relatively inexpensive, and the recording device is compact and maintenance-free, and is used in a wide range of fields.

As an example of this, recently, POS (point)
The to-of-sales label system has come to be used in various manufacturing processes, and even if it is used in a place where the ambient temperature is around 90 ° C., the background fog does not occur, and the recording density of the environment is improved. High thermal recording materials have been demanded.

Conventionally, various sensitizers have been used to increase the recording density, but a heat-sensitive recording material which has sufficiently high sensitivity and does not cause background fog under high temperature conditions has not yet been obtained. .

[0005]

In view of the present situation, the present inventors have found that the background fog does not occur even when exposed to an environmental temperature of about 90 ° C., and the density is sufficient even under such a high temperature environment. In order to provide a thermosensitive recording medium that can maintain a recorded image, the components constituting the recording layer have been extensively studied. As a result, it was found that when a combination of a specific basic colorless dye and a specific coloring agent is used in combination with an emulsion of stearic acid amide having an average particle size of 0.5 μm or less, a desired thermosensitive recording material can be obtained. The invention was completed.

[0006]

SUMMARY OF THE INVENTION The present invention comprises:
In a thermosensitive recording medium provided with a recording layer containing a colorless or light-colored basic dye and a coloring agent, 3-diethylamino-7- (o-chlorophenylamino) fluorane, 3-diamine as a basic dye in the recording layer. (N-butyl) amino-7
At least one selected from-(o-chlorophenylamino) fluorane and 3-diethylamino-7- (m-trifluoromethylphenylamino) fluorane, and a 4-hydroxydiphenylsulfone compound having a melting point of 120 ° C or higher as a colorant And a stearamide amide emulsion having an average particle diameter of 0.5 μm or less.

[0007]

The present invention, as described above, is excellent in background fog in a high temperature environment by using a specific stearic acid amide emulsion in combination with a color forming system containing a specific basic dye and a specific color developing agent. It is a high-sensitivity thermosensitive recording medium.

The 4-point melting point of 120 ° C. or higher used in the present invention
Specific examples of the hydroxydiphenyl sulfone compound include 4-hydroxy-4'-methyldiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone and 4,4'-dihydroxydiphenyl sulfone. , Bis (3-allyl-4-hydroxyphenyl) sulfone, 4
-Hydroxy-3 ', 4'-tetramethylene diphenyl sulfone, 4-hydroxy-3', 4'-trimethylene diphenyl sulfone and the like can be mentioned, but these can be used in combination of two or more if necessary. Among the above-mentioned 4-hydroxydiphenyl sulfone compounds, 2,4 '
-Dihydroxydiphenyl sulfone is preferred as it is consistent with the object of the invention.

In the present invention, the use ratio of the specific basic dye and the specific coloring agent is not particularly limited, but the coloring agent is preferably 50 parts by weight with respect to 100 parts by weight of the basic dye. It is desirable to adjust the amount to be in the range of 1000 parts by weight, more preferably 150 parts by weight to 700 parts by weight.

Further, in the present invention, an average particle size of 0.5 μm is added to the color-forming system containing the above-mentioned specific basic dye and color former.
An emulsion of stearic acid amide of m or less is used together. The amount of this emulsion used is not particularly limited, but in general, the coloring agent 100 is used.
1 to 300 parts by weight, preferably 1 to 300 parts by weight
A range of about 100 parts by weight is desirable.

As described above, in the present invention, 3-diethylamino-7- (o-chlorophenylamino) fluorane, 3
-Di (n-butyl) amino-7- (o-chlorophenylamino) fluorane, 3-diethylamino-7- (m-
At least one of trifluoromethylphenylamino) fluorane is used as a basic dye,
Other basic dyes known in the range that does not impair the effects of the present invention, for example, triarylmethane dyes, diphenylmethane dyes, divinylphthalide dyes, thiazine dyes as described in JP-A-2-239977. Spiro dyes, lactam dyes, fluorane dyes, fluorene dyes and the like can also be used in combination. When other basic dyes are used in combination, it is desirable to adjust the ratio of the other basic dyes in the total basic dyes to 20% by weight or less.

In the present invention, 4-having a specific melting point is used.
Hydroxydiphenyl sulfone is used as a color-developing agent.
It is also possible to use various publicly known colorants such as those described in JP-A-239977.

In the heat-sensitive recording material of the present invention, an emulsion of stearic acid amide having an average particle diameter of 0.5 μm or less is used for the purpose of improving recording sensitivity, but it is known within a range not impairing the object of the present invention. A heat-fusible substance can also be used in combination. Examples of such a heat-fusible substance include stearic acid amide, stearic acid methylenebisamide, stearic acid ethylenebisamide, stearic acid methylolamide, oleic acid amide, palmitic acid amide, coconut fatty acid amide, and other fatty acid amides, p-benzyl. Biphenyl, 1,2-bis (phenoxy) ethane, 1,2-bis (4-methylphenoxy) ethane,
1,2- (3-methylphenoxy) ethane, 1- (4-
Methoxyphenoxy) -2- (2-methylphenoxy)
Ethane, 2-naphthol benzyl ether, benzyl-
Ethers such as 4-methylthiophenyl ether, dibenzyl terephthalate, esters such as 1-hydroxy-2-naphthoic acid phenyl ester, 2,2′-methylenebis (4-methyl-6-tert-butylphenol),
2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,2'-methylidenebis (4,6-
Di-tert-butylphenol), 2,2'-ethylidenebis (4-sec-butyl-6-tert-butylphenol), 4,4'-butylidenebis (6-tert-butyl-
3-methylphenol), 4,4'-thiobis (6-te
rt-Butyl-3-methylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris (5-cyclohexyl-4-hydroxy) 2-Methylphenyl) butane, 1,3,5-Tris [2- (3,5-di-tert-butyl-4-hydroxycinnamoyloxy) ethyl] isocyanurate, 1,3,5-Tris (4 -Tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, tris (3,5-di-tert-butyl-4)
-Hydroxybenzyl) isocyanurate, 2,4,6
-Tris (3 ', 5'-di-tert-butyl-4'-hydroxybenzyl) mesitylene, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] And hindered phenols, and UV absorbers such as 2-hydroxy-4-benzyloxybenzophenone. Among them, those having a melting point of 95 ° C. or higher are preferable.

The coating liquid containing them is generally prepared by using water as a dispersion medium and a dyeing agent, a coloring agent and a phosphoric acid ester compound by an agitating / pulverizing machine such as a ball mill, an attritor, a vertical or horizontal sand mill, and a colloid mill. And the like are dispersed together or separately. In such coating liquid, starch as a binder, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, sulfone group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, Various modified polyvinyl alcohol such as silicone modified polyvinyl alcohol,
Styrene / maleic anhydride copolymer salt, styrene / acrylic acid copolymer salt, styrene / butadiene copolymer emulsion and the like are 2 to 40% by weight of the total solid content, preferably 5
About 25% by weight is blended. Of course, these binders may be used in combination of two or more.

Further, various auxiliaries can be added to the coating liquid, for example, dioctylsulfosuccinic acid sodium salt, dodecylbenzenesulfonic acid sodium salt,
Dispersants such as sodium salt of lauryl alcohol sulfate and fatty acid metal salt, UV absorbers such as benzophenone-based, cyanoacrylate-based and hydroxybenzoate-based,
Other examples include antifoaming agents, fluorescent dyes, coloring dyes and the like.

Further, stearic acid ester wax, polyethylene wax, carnauba wax, microcrystalline wax, so as to prevent the thermal recording material from sticking due to contact with a recording device or recording head.
It is also possible to add a dispersion liquid or emulsion of carboxy-modified paraffin wax, zinc stearate, calcium stearate or the like.

In addition, kaolin, clay, talc, calcium carbonate,
Magnesium carbonate, calcined clay, titanium oxide, diatomaceous earth,
Inorganic pigments such as particulate anhydrous silica and activated clay, organic pigments such as styrene microballs, nylon powder, polyethylene powder, urea / formalin resin filler, and raw starch granules can also be added.

In the heat-sensitive recording material of the present invention, the method for forming the recording layer is not particularly limited, and the recording layer can be formed according to a well-known and conventional technique. For example, the coating liquid for the heat-sensitive recording layer is air-coated on the support. Examples thereof include a method of forming a recording layer by coating and drying with a suitable coating device such as a knife coater, a blade coater, a bar coater, a die coater, a gravure coater, and a curtain coater.

The coating amount of the coating liquid is not particularly limited, and generally 1.0 to 12 g / m 2 in dry weight.
² , preferably in the range of 1.5 to 10 g / m ² . As the support, paper, plastic film, synthetic paper and the like are used, but paper is preferable in terms of cost and coating suitability, and synthetic paper is preferable in view of color density.

The thermal recording material of the present invention thus obtained is
Since a stearamide emulsion with a specific particle size is used in combination with a color development system that contains a combination of a specific basic dye and a coloring agent, the whiteness and recording density decrease even when exposed to high temperature conditions. Is extremely small, and exhibits excellent characteristics of high recording sensitivity.

In the present invention, it is possible to further improve the storability of a recorded image by providing a resin layer on the heat-sensitive recording material and / or on the back surface side, if necessary.
Further, in the field of heat-sensitive recording material manufacturing, such as providing an undercoat layer on the support to improve image quality and sensitivity, processing the back surface of the recording material into an adhesive label by processing with an adhesive, and providing a magnetic layer on the back surface of the recording material. Various known techniques can be added. Further, the image quality and the image density can be improved by performing a super calendering process after forming the recording layer.

[0022]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Unless otherwise specified, parts and% in the examples represent parts by weight and% by weight, respectively.

Example 1 [Formation of Intermediate Layer] Calcined clay (trade name: Ancilek)
100 parts, styrene / butadiene co-weight
Combined latex (solid content: 50%) 15 parts, 10% poly
From 30 parts of vinyl alcohol aqueous solution and 200 parts of water
The following compositions were mixed to prepare a coating liquid for the intermediate layer. Obtained
50g / m²7g of coating amount after drying on high quality paper
/ M ²Was applied and dried to form an intermediate layer.

[Preparation of solution A] 3-diethylamino-7-
A composition comprising 10 parts of (o-chlorophenylamino) fluorane, 10 parts of a 5% aqueous solution of methylcellulose, and 10 parts of water was subjected to a horizontal sand mill to have an average particle size of 0.8 μm.
It was crushed until it became. [Preparation of solution B] A composition consisting of 25 parts of 2,4'-dihydroxydiphenyl sulfone, 5 parts of a 5% aqueous solution of methylcellulose, and 40 parts of water was pulverized by a horizontal sand mill until the average particle diameter became 0.5 µm.

[Formation of Recording Layer] Liquid A 30 parts, Liquid B 70
Part, stearic acid amide emulsion 21.5% dispersion liquid (trade name: High Micron G-270, manufactured by Chukyo Yushi Co., Ltd.,
45 parts of average particle diameter 0.4 μm, light calcium carbonate (trade name: Callite KT, manufactured by Shiraishi Calcium Co., Ltd.) 30
Part, 10% polyvinyl alcohol aqueous solution 80 parts, 10%
80 parts of an aqueous solution of oxidized starch, 10 parts of a 30% aqueous dispersion of zinc stearate, and 75 parts of water were mixed and stirred to obtain a coating liquid for heat-sensitive recording layer. The obtained coating liquid is smeared on the above intermediate layer with a varibar so that the coating amount after drying is 4 g / m ² .
After drying, a super-calender process was performed to obtain a heat-sensitive recording material.

Example 2 Example 3 except that 3-diethylamino-7- (m-trifluoromethylphenylamino) fluorane was used in place of 3-diethylamino-7- (o-chlorophenylamino) fluorane in the preparation of solution A. A thermal recording material was obtained in the same manner as in 1.

Example 3 In preparation of solution A, 3-di (n-butyl) amino-7- (o-chlorophenylamino) fluorane was used in place of 3-diethylamino-7- (o-chlorophenylamino) fluorane. A thermal recording material was obtained in the same manner as in Example 1.

Comparative Example 1 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that a 21.5% emulsion of stearic acid amide was not used in the formation of the recording layer.

Comparative Example 2 [Preparation of Solution C] A composition consisting of 10 parts of stearic acid amide, 3 parts of a 5% aqueous solution of methylcellulose, and 32 parts of water was pulverized by a horizontal sand mill until the average particle size became 1.2 μm. [Formation of Recording Layer] In the formation of the recording layer, a thermosensitive recording medium was obtained in the same manner as in Example 1 except that 45 parts of C liquid was used instead of 45 parts of 21.5% dispersion of stearic acid amide emulsion. It was

Comparative Example 3 [Preparation of solution D] A composition comprising 10 parts of 1,2- (3-methylphenoxy) ethane, 3 parts of a 5% aqueous solution of methylcellulose, and 32 parts of water was used to obtain an average particle size of 1 using a horizontal sand mill. It was pulverized until it became 0.0 μm. [Formation of Recording Layer] In the formation of the recording layer, a thermosensitive recording medium was obtained in the same manner as in Example 2 except that 45 parts of the D solution was used instead of 45 parts of the 21.5% stearic acid amide emulsion. It was

Comparative Example 4 The same procedure as in Example 1 was carried out except that a stearic acid amide emulsion (average particle size of 0.9 μm was used in place of the stearic acid amide emulsion (average particle size of 0.4 μm) in forming the recording layer. A thermosensitive recording material was obtained.

Comparative Example 5 In the preparation of solution A, 3- (N-N was used instead of 3-diethylamino-7- (o-chlorophenylamino) fluorane.
-Ethyl-N-isoamyl) amino-6-methyl-7-
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that anilinofluoran was used.

Comparative Example 6 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 4,4'-isopropylidenediphenol was used instead of 2,4'-dihydroxydiphenylsulfone in the preparation of solution B.

The obtained 9 kinds of heat-sensitive recording materials were applied to Matsushita Simulator MF-1 (applied voltage: 16 V, pulse width: 4 m).
s). The density of the obtained recorded image and the density of the background portion were measured with a Macbeth densitometer (RD-914 type, manufactured by Macbeth Co.), and the results are shown in Table 1.

Next, the heat-sensitive recording material after recording was treated in a hot air dryer at 95 ° C. for 5 hours, and the density of the background part was measured with a Macbeth densitometer to evaluate the background fog under high temperature conditions. The results are also shown in Table 1.

[0036]

[Table 1]

[0037]

As is clear from the results shown in Table 1, the thermosensitive recording medium of the present invention is a high-sensitivity thermosensitive recording medium with little background fog even when exposed to high temperature conditions.

Claims (1)

[Claims] 1. A thermosensitive recording medium comprising a support and a recording layer containing a colorless or light-colored basic dye and a coloring agent, and 3-diethylamino-7- (as a basic dye in the recording layer. o-chlorophenylamino) fluorane, 3-
Di (n-butyl) amino-7- (o-chlorophenylamino) fluorane and 3-diethylamino-7- (m-
At least one selected from trifluoromethylphenylamino) fluorane and a melting point of 12 as a colorant.
At least one 4-hydroxydiphenyl sulfone compound at 0 ° C. or higher is contained, and the average particle size is 0.5.
A heat-sensitive recording material comprising an emulsion of stearic acid amide having a size of not more than μm.