JPH06297849A - Heat-sensitive recording material - Google Patents

Abstract

PURPOSE:To provide a heat-sensitive recording material which has high sensitivity and does not generate a picking phenomenon at the time of printing. CONSTITUTION:An intermediate layer forming solution is prepared by mixing agitating a 1.0 pts. hollow filler having a hollow ratio of 30%, 0.2 pts. styrene/ butadiene tex and 0.1 pts. PVA. Then a heat-sensitive color development solution is prepared by mixing agitating a dye dispersing solution comprised of 3-(N- methyl-N-cyclohexyl)amino-6-methyl anilino fluorane, PVA and water and a dispersing solution of a developer comprised of 1,5-di(4-hydroxyphenylthio)-3- oxapentane, calcium carbonate, PVA and water at a weight ratio of 1:3. Then the intermediate layer forming solution, heat-sensitive color development layer forming solution and a protective layer forming solution are applied onto wood free paper in this order.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosensitive recording material utilizing a color forming reaction between a leuco dye and a color developing agent, and more specifically, an intermediate layer is provided between a support and a thermosensitive coloring layer. The present invention relates to a thermosensitive recording material having various properties improved.

[0002]

2. Description of the Related Art Heretofore, various thermosensitive recording materials have been known in which a thermosensitive coloring layer containing a leuco dye and a color developing agent as a main component is provided on a support. Is recorded and is widely used in the fields of computer output, calculators and other printers, medical measurement recorders, facsimiles, automatic ticket vending machines, heat-sensitive labels, heat-sensitive copying, and the like.

On the other hand, recently, there has been a strong demand for higher sensitivity of the heat-sensitive recording material in response to a reduction in power supply accompanying downsizing of a recording apparatus and a reduction in printing energy accompanying an increase in recording speed.

Various methods have been proposed in which an underlayer is used between a support and a heat-sensitive color developing agent in order to improve the heat insulating property and the uniformity of color development in order to improve the sensitivity of the heat-sensitive recording material. For example, a method using heat-foamable hollow plastic pigments or non-foamable glass or fine hollow particles having an aluminosilicate as a shell (JP-A-59-50).
93, JP-A-60-248390, etc.),
There is a method of using a two-layer type under layer in which a pigment layer is provided on a layer containing non-expandable fine hollow particles having a thermoplastic resin as a shell (JP-A-62-5886).

Further, a method of using an under layer containing a thermoplastic resin as a shell and a non-expandable micro hollow sphere having a hollow ratio of 30% or more as a main component (JP-A-2-214688).
Etc.

[0006]

When the intermediate layer is mainly composed of the non-expandable micro hollow spheres and a hydrophobic resin is used as the binder, the effect of improving the sensitivity is sufficient, but the printing process There is a problem that a picking phenomenon occurs at the time and a printing defect occurs. When a water-soluble resin is used,
Although the picking phenomenon does not occur during printing, it is improved, but the effect of improving sensitivity is remarkably reduced, and water peeling resistance ("water peeling" is the property that the intermediate layer elutes and peels off when water is submerged. ) Was a problem.

The present invention is intended to solve the above-mentioned problems, and an object thereof is to use the non-foaming micro hollow spheres,
It is an object of the present invention to provide a heat-sensitive recording material that does not cause a picking phenomenon during printing processing, has good water resistance and peeling resistance, and has improved sensitivity.

[0008]

According to the present invention (Claim 1), there is provided a thermosensitive recording material having a thermosensitive coloring layer containing a leuco dye and a color developer as main components on the support. Provided is an intermediate layer containing a hollow filler as a main component between the thermosensitive coloring layer, and a hydrophobic resin and a water-soluble resin are used in combination as a resin in the intermediate layer to provide a thermosensitive recording material. It The heat-sensitive recording material of the present invention has high sensitivity, does not cause a picking phenomenon during printing, and has excellent water resistance and peeling resistance.

In the heat-sensitive recording material of the present invention, the weight ratio of the hollow filler / all resins (sum of hydrophobic resin and water-soluble resin) is 1.0 / 0.4 or more (2.5 or more) (claim) Item 2) further improves the sensitivity.

Further, in the heat-sensitive recording material of the present invention, the weight ratio of the hydrophobic resin / water-soluble resin is set to 1.0 / 0.5 or more (2.0 or more) (claim 3) to improve the sensitivity. The decrease does not occur, and the picking phenomenon of the printing resin does not occur.

The present invention will be described in detail below. In the heat-sensitive recording material of the present invention, its sensitivity is most affected by the heat insulating effect of the hollow filler. However, when a water-soluble resin is used as the binder, the sensitivity of the binder of the intermediate layer when applying the heat-sensitive color developing layer is improved. The elution into the heat-sensitive color-developing layer increases the amount of resin components in the heat-sensitive color-developing layer, resulting in a decrease in sensitivity. Therefore, a hydrophobic resin is generally used as the resin when the hollow filler is used in the intermediate layer.

On the other hand, the sensitivity is basically a heat-melting reaction between the dye and the color developer, and therefore, the non-melted material in the heat-sensitive color-forming layer during heating, particularly the resin component, hinders color development. We are trying to increase the sensitivity by reducing it. Therefore, the interlayer binding force of the sensitivity coloring layer is weak and the picking phenomenon during printing is likely to occur.

When the thermosensitive coloring layer is provided on the intermediate layer containing a hollow filler and a hydrophobic resin as a main component, picking phenomenon occurs during printing although the sensitivity is not lowered. Therefore, as a result of intensive studies by the present inventors, by mixing a hydrophobic resin and a water-soluble resin in a specific weight ratio, and further by providing an intermediate layer using a hollow filler and the total resin in a specific weight ratio, high sensitivity can be achieved. Moreover, it has been found that an excellent thermosensitive recording material can be obtained in which picking phenomenon does not occur during printing.

Examples of the hydrophobic resin used in the intermediate layer of the present invention include styrene-butadiene latex, polyvinyl acetate emulsion, polyacrylic acid ester emulsion, polyurethane emulsion, and the water-soluble resin includes polyvinyl alcohol and starch. , Cellulose, casein, isobutylene maleic anhydride copolymer and the like.

Next, the chemicals used in the present invention will be specifically described below. As the thermosensitive color-forming layer-constituting chemical, various types are known as basic dyes which are colorless or light-colored, and examples thereof include the following.

3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3,3-bis (p
-Dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindole -3-yl)
Phthalide, 3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide,

3,3 bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-
Bis (9-ethylcarbazol-3-yl) -6-dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -6-dimethylaminophthalide,

3-p-dimethylaminophenyl-3-
Triallylmethane dyes such as (1-methylpyrrol-3-yl) -6-dimethylaminophthalide; 4,4′-bis-dimethylaminobenzhydrylbenzyl ether,
N-halophenyl-leukoauramine, N-2,4,5
-Diphenylmethane dyes such as trichlorophenyl leuco auramine; benzoyl leuco methylene blue, p-
Thiazine dyes such as nitrobenzoyl leuco methylene blue;

3-methyl-spiro-dinaphthopyran, 3
Spiro dyes such as -ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho (6'-methoxybenzo) spiropyran, 3-propyl-spiro-dibenzopyran ;

Rhodamine-B-aninolactam, rhodamine (p-nitroanilino) lactam, rhodamine (o
A lactam dye such as chloroanilino) lactam;

3-dimethylamino-7-methoxyfluorane, 3-diethylamino-6-methoxyfluorane,
3-diethylamino-7-methoxyfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6,7-dimethylfluorane,

3- (N-ethyl-p-toluidino) -7
-Methylfluorane, 3-diethylamino-7-N-acetyl-N-methylaminofluorane, 3-diethylamino-7-N-methylaminofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino -7-N-methyl-N-benzylaminofluorane,

3-diethylamino-7-N-chloroethyl-N-methylaminofluorane, 3-diethylamino-7-N-diethylaminofluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7- Phenylaminofluorane, 3- (N-ethyl-p-toluidino)-
6-methyl-7- (p-toluidino) fluorane, 3-
Diethylamino-6-methyl-7-phenylaminofluorane,

3-dibutylamino-6-methyl-7-phenylaminofluorane, 3-diethylamino-7-
(2-carbomethoxy-phenylamino) fluorane,
3- (N-cyclohexyl-N-methylamino) -6-
Methyl-7-phenylaminofluorane, 3-pyrrolidino-6-methyl-7-phenylaminofluorane, 3-
Piperidino-6-methyl-7-phenylaminofluorane,

3-diethylamino-6-methyl-7-xylidinofluorane, 3-diethylamino-7- (o-
Chlorophenylamino) fluorane, 3-dibutylamino-7- (o-chlorophenylamino) fluorane, 3
-Pyrrolidino-6-methyl-7-p-butylphenylaminofluorane, 3- (N-methyl-Nn-amyl)
Amino-6-methyl-7-phenylaminofluorane,

3- (N-ethyl-Nn-amyl) amino-6-methyl-7-phenylaminofluorane, 3-
(N-ethyl-N-isoamyl) amino-6-methyl-
7-phenylaminofluorane, 3- (N-methyl-N
-N-hexyl) amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl-N-n-hexyl) amino-6-methyl-7-phenylaminofluorane,

3- (N-ethyl-N-β-ethylhexyl) amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl-N-tetrahydrofurfuryl)
Amino-6-methyl-7-phenylaminofluorane,
3- (N-ethyl-N-cyclopentyl) amino-6-
Fluorane dyes such as methyl-7-phenylaminofluorane.

Of course, the dyes are not limited to these dyes, and two or more dyes may be used in combination.

Various kinds of inorganic or organic acidic substances are known, which are colored by contact with the basic dye.
For example, the following is exemplified.

Activated clay, acid clay, attapulate,
Inorganic acidic substances such as bentonite, colloidal silica, aluminum silicate;

4-tert-butylphenol, α-naphthol, β-naphthol, 4-acetylphenol,
4-tert-octylphenol, 4,4'-sec
-Butylidene diphenol, 4-phenylphenol,
4,4'-dihydroxy-diphenylmethane, 4,4 '
-Isopropylidenediphenol, 2,2-bis (4-
Hydroxyphenyl) -4-methylpentane, hydroquinone, 4,4′-cyclohexylidene diphenol,
4,4 '-(1,3-dimethylbutylidene) bisphenol, 4,4'-dihydroxydiphenyl sulfide,

4,4'-thiobis (6-tert-butyl-3-methylphenol), 4,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-methyldiphenyl sulfone, 4-hydroxy-4'-methoxy Diphenyl fluphone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, 4-hydroxy-3 ', 4'
-Trimethylene diphenyl sulfone, 4-hydroxy-
3 ', 4'-tetramethylene diphenyl sulfone, 3,
4-dihydroxy-4′-methyldiphenyl sulfone,
Bis (3-allyl-4-hydroxyphenyl) sulfone,

1,3-di [2- (4-hydroxyphenyl) -2-propyl] benzene, hydroquinone monobenzyl ether, bis (4-hydroxyphenyl) acetic acid butyl ester, 4-hydroxybenzophenone, 2,4
-Dihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone,

Dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, ethyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate, sec-butyl 4-hydroxybenzoate, pentyl 4-hydroxybenzoate, 4- Phenyl hydroxybenzoate, benzyl 4-hydroxybenzoate, tolyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, phenylpropyl 4-hydroxybenzoate, phenethyl 4-hydroxybenzoate, 4-hydroxybenzoic acid-p-chloro. Phenolic compounds such as benzyl, 4-hydroxybenzoic acid-p-methoxybenzyl, novolac type phenol resin, and phenol polymer;

Benzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, 3-sec-
Butyl-4-hydroxybenzoic acid, 3-cyclohexyl-4-hydroxybenzoic acid, 3,5-dimethyl-4-hydroxybenzoic acid, salicylic acid, 3-isopropylsalicylic acid, 3-tert-butylsalicylic acid, 3,5-di -Tert-butylsalicylic acid, 3-benzylsalicylic acid, 3- (α-methylbenzyl) salicylic acid, 3-chloro-5- (α-methylbenzyl) salicylic acid, 3-phenyl-5- (α, α-dimethylbenzyl) salicylic acid ,
Aromatic carboxylic acids such as 3,5-di-α-methylbenzylsalicylic acid, and their phenolic compounds, aromatic carboxylic acids and polyvalent compounds such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin and nickel An organic acidic substance such as a salt with a metal. It should be noted that, of course, these colorants may be used in combination of two or more, if necessary.

The ratio of the basic dye and the color-developing agent to be used is appropriately selected according to the type of the basic dye or the color-developing agent used and is not particularly limited, but generally 1 weight of the basic dye is used. 1 to 50 parts by weight, preferably 1 to 1
About 0 parts by weight of the coloring agent is used.

In order to prepare a thermosensitive color developing layer coating liquid containing these substances, generally, water is used as a dispersion medium, and a dye and a coloring agent are used together or separately by a stirring / grinding machine such as a ball mill, an attritor or a sand mill. It is prepared by dispersing.

In such a coating liquid, starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polo vinyl alcohol, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride are usually used as binders. Acid copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, natural rubber emulsion, styrene / butadiene copolymer emulsion, acrylonitrile / butadiene copolymer emulsion, methyl methacrylate / butadiene copolymer Polymer emulsion, polychloroprene emulsion, vinyl acetate emulsion, ethylene-vinyl acetate emulsion, etc.
10 to 70% by weight of the total solid content of the thermosensitive coloring layer, preferably 1
About 5 to 50% by weight is added.

Further, various auxiliary agents can be added to the coating solution, for example, sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, lauryl alcohol sulfate / sodium salt, alginate, fatty acid metal salt and the like. Dispersants; UV absorbers such as benzophenone type and triazole type; other defoaming agents; fluorescent dyes; coloring dyes and the like.

If necessary, lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax and ester wax; calcium carbonate, zinc oxide, aluminum oxide,
Inorganic pigments such as titanium dioxide, silicon dioxide, aluminum hydroxide, barium sulfate, zinc sulfate, talc, kaolin, clay, calcined clay, colloidal silica; styrene microballs, nylon powder, polyethylene powder, urea / formalin resin filler, raw starch Organic pigments such as stearic acid amide, stearic acid methylenebisamide, oleic acid amide, palmitic acid amide, coconut fatty acid amide, and other fatty acid amides;

Dibenzyl phthalate, 1,2-di (3-
Methylphenoxy) ethane, 1,2-diphenoxyethane, 4,4′-ethylenedioxy-bis-benzoic acid diphenylmethyl ester, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-) Butylphenyl)
Butane, 2,2'-methylenebis (4-methyl-6-t
ert-butylphenol), 4,4′-butylidenebis (6-tert-butyl-3-methylphenol) and other hindered phenols, and various known heat-fusible substances can be added.

When an inorganic or organic pigment is contained in the thermosensitive coloring layer, it is preferable to use a pigment having a particle diameter as small as possible, and it is particularly preferable to use a pigment having an average particle diameter of 2 μm or less.

In the present invention, the method for forming the thermosensitive coloring layer is not particularly limited, and the coating solution is applied onto the intermediate layer by a coating apparatus equipped with an appropriate coater head such as an air knife coater or a blade coater. It is formed by a method of drying. Further, the coating amount of the coating liquid is not particularly limited, and is usually ² to 12 g / m ² in dry weight,
The range is preferably about 3 to 10 g / m ² .

After applying and drying the intermediate layer and / or the heat-sensitive coloring layer, a smoothing treatment such as super calendering can be applied if necessary.

Further, it is possible to provide an overcoat layer (protective layer) on the heat-sensitive color developing layer for the purpose of protecting the heat-sensitive color developing layer, and various backing layers such as a backing layer may be provided on the support. The publicly known technique of can be applied. The overcoat layer is composed mainly of a resin, a pigment, a lubricant, etc., and examples of the chemicals used include the same chemicals as those for forming the thermosensitive coloring layer.

[0044]

EXAMPLES Next, the present invention will be described in detail with reference to Examples. All parts and% shown below are based on weight.

Example 1 A mixture having the following composition was stirred and mixed with a disper to prepare an intermediate layer forming liquid. In this case, the compounding ratio of each component (the ratio in the dry state) is as shown in [Table 1] below. [Intermediate layer forming liquid] Hollow filler: Hollow filler having a styrene / acrylic copolymer shell and a hollow ratio of 30% Hydrophobic resin: Styrene / butadiene latex Water soluble resin: PVA

[0046]

[Table 1]

[Thermosensitive color forming layer forming liquid] A mixture having the following composition was pulverized and dispersed by an attritor for 24 hours to prepare a dispersion liquid having an average particle diameter of 2 to 3 µm. Dye dispersion: 3- (N-methyl-N-cyclohexyl) amino-6-methylanilinofluoran 20 parts PVA 10% solution 20 parts water 60 parts Dispersing liquid for color developer: 1,5-di ( 4-Hydroxyphenylthio) -3-oxapentane 20 parts Calcium carbonate 10 parts PVA 10% solution 30 parts Water 40 parts The above dye dispersion liquid: developer dispersion liquid is mixed in a weight ratio of 1: 3. -The mixture was stirred to prepare a thermosensitive color forming layer forming liquid.

[Protective Layer Forming Liquid] A mixture having the following composition was pulverized and dispersed by an attritor for 14 hours to prepare a pigment / lubricant dispersion having an average particle diameter of 2 to 3 μm. Kaolin 10 parts Zinc stearate 1 part PVA 10% solution 10 parts Next, this pigment / lubricant dispersion and the PVA 10% solution are mixed and stirred at a weight ratio of 21: 100 to prepare a protective layer forming solution. did.

The above-mentioned intermediate layer forming liquid is applied onto high-quality paper so as to have a dry adhesion amount of only the hollow filler of 39 g / m ² and dried to form an intermediate layer, on which the above-mentioned thermosensitive coloring layer forming liquid is formed. After coating and drying so that the dry adhesion amount becomes 6 g / m ² , a thermosensitive coloring layer is formed, and then the protective layer forming liquid is applied on the thermosensitive coloring layer so that the dry adhesion amount becomes 3 g / m ^2. -Drying to form a protective layer, the surface of this protective layer was surface-treated with a super calender, and the sample of Example 1 was prepared with a main-ken smoothness of about 1000 seconds.

Example 2 A sample was prepared in the same manner as in Example 1 except that the preparation conditions of the intermediate layer forming liquid were set as shown in [Table 1] above.

Example 3 A sample was prepared in the same manner as in Example 1 except that an acrylic emulsion was used as the hydrophobic resin in the preparation of the intermediate layer forming liquid.

Example 4 A sample was prepared in the same manner as in Example 1 except that starch was used as the water-soluble resin in the preparation of the intermediate layer forming liquid.

Comparative Examples 1 to 4 Samples were prepared in the same manner as in Example 1 except that the preparation conditions for the intermediate layer forming liquid were set as shown in [Table 1] above.

With respect to each of the samples obtained as described above, the sensitivity and the picking property during printing were evaluated. [Sensitivity evaluation] A thermal printing device (manufactured by Matsushita Electronic Components Co., Ltd.) was used, and head power was 0.45 W / dot and pulse width was 1.0 m.
The density when printed in sec is Macbeth densitometer RD-9
It was measured at 14. [IGT Picking Test] An IGT printing machine was used as a printing machine, and standard tack inks (10, 15, 20) manufactured by Toyo Ink Co., Ltd. were used as standard inks to investigate whether or not a picking phenomenon occurs during printing. The above evaluation results are shown in [Table 2].

[0055]

[Table 2] [Note] ○: No picking △: Partially picking ×: Picking

From the results shown in [Table 2], it can be seen that the heat-sensitive recording material of the present invention has high sensitivity and is an excellent heat-sensitive recording material in which picking does not occur during printing.

[0056]

As is clear from the above description, in the heat-sensitive recording material of the present invention, the intermediate layer formed by using the hollow filler, the hydrophobic resin and the water-soluble resin together in a specific weight ratio is provided with the support and the heat-sensitive coloring. By providing between the layer, high sensitivity,
In addition, there is an effect that it becomes an excellent heat-sensitive recording material in which picking phenomenon does not occur during printing.

Claims (3)

[Claims] 1. A thermosensitive recording material having a thermosensitive coloring layer mainly composed of a leuco dye and a color developer on a support, wherein a hollow filler is contained as a main component between the support and the thermosensitive coloring layer. A heat-sensitive recording material, characterized in that a hydrophobic resin and a water-soluble resin are used together as a resin in the intermediate layer. 2. The heat-sensitive recording material according to claim 1, wherein a weight ratio of the hollow filler / all resins (sum of hydrophobic resin and water-soluble resin) is 1.0 / 0.4 or more. . 3. The weight ratio of the hydrophobic resin / water-soluble resin is 1.0 / 0.5 or more.
The heat-sensitive recording material described in.