JPH07314891A - Heat-sensitive multiple duplicating paper - Google Patents

Abstract

PURPOSE:To provide a heat-sensitive multiple duplicating paper of superior preservative stability of a heat-sensitive recording layer of a first recording sheet as an upper sheet which can get simultaneously two sheets of recording of high fastness and high physical recognition by one printing. CONSTITUTION:A duplicating paper is formed by the combination of an upper sheet I provided with a heat-sensitive recording layer A composed of aliphatic acid ferric salt and a chelate agent as main components formed on one face of a base sheet and a heat fusible layer B containing a colorless or light-color basic dye and a heat fusible substance formed on the other face, and a lower sheet II with a heat-sensitive color developing layer C containing a coloration agent for the coloration of the basic dye formed on one face of a base sheet 2.

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 multiplex copying paper excellent in image visibility and storage stability.

[0002]

2. Description of the Related Art A heat-sensitive recording material which utilizes a coloring reaction between a colorless or light-colored basic dye and an organic or inorganic coloring agent to bring both coloring substances into contact with each other by heat to obtain a recorded image is often used. Are known. Such a thermal recording material is relatively inexpensive,
Also, since the recording equipment is compact and its maintenance is easy,
It is used not only as a recording medium for facsimiles and various computers but also in a wide range of fields. In particular, since thermal recording materials have begun to be used as receipts, it has been strongly desired that a plurality of sheets can be recorded by one printing and that each record has high storability.

However, although multiple recording can be performed by printing a plurality of heat-sensitive papers in piles, heat transfer is insufficient and satisfactory recording cannot be performed. Therefore, various proposals have been made for heat-sensitive multiple copy papers. But there is not always satisfactory.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
Japanese Laid-Open Patent Publication No. 115229 discloses a technique in which a heat-meltable ink layer containing a colored pigment is provided on the back surface of the upper paper (I), which is combined with a so-called thermal transfer technique to improve the recording property. Although this technology certainly has good storage and recording characteristics, since a heat-meltable ink layer containing a colored pigment is provided on the back surface of the top paper (I), this layer can be seen through the base sheet, The background is colored and there is a problem in the visibility of the recorded image of the layer containing the colorless or light-colored basic dye of the upper paper (I) and the coloring agent, or the heat fusion containing the colored pigment of the upper paper (I). There is a handling problem that the functional ink layer contaminates fingers and clothes during handling.

To solve this problem, JP-A-57-96
No. 895, a base sheet (1) has a layer (A ′) containing a colorless or light-colored basic dye and a coloring agent on the surface thereof, and has a colorless or light-colored basic dye and a heat fusible substance on the back surface. A heat-sensitive multiplex copying paper comprising an upper paper (I) having a layer (B) containing a substance and a lower paper (II) having a layer (C) containing a colorant on the surface of a substrate sheet (2). Was disclosed.

Since (B) and (C) are separated from each other in this heat-sensitive multiplex copying paper, a light-colored basic dye and a color-developing agent which enhance the fastness of the image can be used. However, in general, coexistence of a light-colored basic dye and a coloring agent that increase the fastness in the same layer makes it easy for the background to be covered, or when stored under high temperature or high humidity, the background becomes more covered. There is such a problem that it is difficult to visually recognize the image.

On the other hand, in a general thermal paper in which a colorless or light-colored basic dye and a color developing agent are contained in the same layer, a light-colored basic dye used while balancing the fog of the background and the fastness of the image is used. A coloring agent is selected. Since the above layer (A ') is an ordinary heat-sensitive recording layer having a light-colored basic dye and a coloring agent in the same layer, the storage stability of the image eventually becomes a problem.

According to the present invention, the thermal recording layer provided on the surface of the upper paper (I) has excellent storage stability and high fastness in one printing.
It is an object of the present invention to provide a heat-sensitive multiplex copying paper which can simultaneously obtain two highly visible records.

[0009]

In order to eliminate this drawback, the present inventors have provided a heat-sensitive recording layer provided on the surface of top paper (I) with a heat-sensitive recording layer containing a ferric acid fatty acid salt and a chelating agent as main components. I found that the purpose can be achieved by (A).

The thermal recording layer (A) containing a ferric acid fatty acid salt and a chelating agent as main components will be described in more detail.
A specific example of the fatty acid ferric iron salt used in the thermosensitive coloring layer is a ferric salt of a linear or branched saturated fatty acid or unsaturated fatty acid having 6 to 25 carbon atoms, preferably 9 to 22 carbon atoms. ,
More specifically, ferric stearate, ferric myristic acid, ferric behenate, ferric lauric acid, ferral pelargonate, and the like.

Particularly, the height (H) of the main peak and the peak half value width (W) existing within the range of the diffraction angle (2θ) of 21.8 ± 0.5 degrees in the X-ray diffraction analysis curve with Cu-Kα ray. ) And the ratio (H / W) is 10 or more, and
The main endothermic peak in the differential thermal analysis curve is 100
A ferric fatty acid ferric salt composed of a ferric stearate salt, a ferric behenate salt, or a mixture thereof having a high crystallinity and having a temperature of not less than 0 ° C. is preferable.

The chelating agent used in the heat-sensitive coloring layer is polyhydric phenol, dithiocarbamate, diphenylcarbazone, hexamethylenetetramine, spirobenzopyran, 1-formyl-4-phenylsemicarbazide and the like. These chelating agents form chelating compounds with fatty acid ferric salts. Since the chelate compound of the ferric acid fatty acid salt and the chelating agent has absorption in the near-infrared region, a color image readable by a semiconductor laser is formed on the thermosensitive color developing layer of the thermosensitive recording medium of the present invention. It

As the chelating agent, polyhydric phenol is most often used, and among them, gallic acid ester and dihydroxybenzoic acid ester are preferable, and propyl gallate, octyl gallate, lauryl gallate, cetyl gallate, gallic acid are preferred. Examples include stearyl and behenyl gallate.

Dithiocarbamate is also used as a chelating agent, and zinc butylxanthogenate, zinc dibutyldithiocarbamate, zinc N-ethyl-N-phenyldithiocarbamate, zinc dibenzyldithiocarbamate, zinc N-pentamethylenedithiocarbamate, etc. Is exemplified. The mixing ratio of the ferric acid fatty acid salt and the chelating agent is 0.
It is 5 to 3 parts by weight, preferably 1.2 to 1.8 parts by weight.

The water-soluble or water-dispersible binder used for forming the thermosensitive coloring layer includes various starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol and styrene-anhydrous. Water-soluble binders such as maleic acid copolymers and ethylene-maleic anhydride copolymers, and styrene-butadiene copolymers, acrylonitrile-butadiene copolymers, acrylic ester-butadiene copolymers, etc. A binder or the like.

In order to prevent fogging of the coating solution, the pH of the coating solution proposed by the inventor of the present invention to be 6 to 9 and the addition of an additive such as ammonium zirconium carbonate will further improve the performance. improves.

It is necessary to add a pigment to the coating solution for forming the heat-sensitive color forming layer in order to prevent sticking and adhesion of the melt to the thermal head. As a pigment,
Diatomaceous earth, clay, calcined clay, talc, kaolin,
Inorganic pigments such as calcined kaolin, titanium oxide, zinc oxide, silicon oxide, alumina, aluminum hydroxide and synthetic aluminum silicate, and organic pigments such as polystyrene, polymethacrylic acid ester, urea resin and urea-formalin resin are preferably used.

Furthermore, for the purpose of preventing head wear and sticking, higher fatty acid metal salts such as zinc stearate, waxes such as paraffin, oxidized paraffin, polyethylene, oxidized polyethylene, stearamide, and castor wax are also used. Sensitivity improvers such as metatarphenyl, parabenzylbisphenyl, esters of hydroxynaphthoic acid, stearic acid amide, tribenzylamine, naphthalene derivatives, dibenzyl terephthalate, dibenzyl oxalate, bis (paramethylbenzyl oxalate) and other oxalic acids Esters and the like can be added if necessary.

Further, a dispersant such as sodium dioctylsulfosuccinate, an ultraviolet absorber such as a benzophenone type and a benzotriazole type, and various storage stabilizers such as a surfactant and a fluorescent dye, an antistatic agent, a colorant and the like are added. Agents are also added as desired.

The coating liquid for forming the heat-sensitive recording layer is prepared in substantially the same manner as the conventional coating liquid for forming the basic dye type heat-sensitive color developing layer. Specifically, an aqueous dispersion containing a ferric acid fatty acid as a main component and an aqueous dispersion containing a chelating agent as a main component are separately used by using a sand grinder, an attrider, a ball mill or the like. It is adjusted by mixing both the liquids after they are obtained or after they are dispersed by using the emulsion dispersion method.

The heat fusible layer (B) containing a colorless or light basic dye and a heat fusible substance will be described. The heat-fusible layer (B) is formed by heating and melting the heat-fusible substance and then dissolving the basic dye to prepare a coating solution, which is applied to the back surface of the substrate sheet (1) in a heated state. Therefore, the heat-fusible substance serves as a binder for the basic dye.

The basic dyes include (1) triarylmethane compounds such as 3,3-bis (p-dimethylaminophenyl)
-6-Dimethylaminophthalide (Crystal Violet Lactone), 3- (p-Dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl)
Phthalide, 3- (p-dimethylaminophenyl) -3-
(2-Phenylindol-3-yl) phthalide, 3,
3-bis- (p-ethylcarbazol-3-yl) -3
-Dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -5-dimethylaminophthalide, etc .;

(2) Diphenylmethane compound For example, 4,4-bis-dimethylaminobenzhydrin benzyl ether, N-halophenylleuco auramine, N-2,4,5-trichlorophenyl leuco auramine and the like;

(3) Xanthene compound For example, rhodamine B-anilinolactam, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-butylaminofluorane, 3-diethylamino-7- (2- Chloroanilino) fluoran, 3
-Diethylamino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3-ethyl-tolylamino-6-methyl-7-anilinofluorane, 3-cyclohexyl- Methylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7- (β-ethoxyethyl) aminofluorane, 3-diethylamino-6-chloro-7-
(Γ-chloropropylaminofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-N
-Cyclohexyl-N-methylamino-6-methyl-7
-Anilinofluorane, 3-diethylamino-7-phenylfluorane, 3- (N-isoamyl-N-ethylamino) -6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7 -Anilinofluorane, etc .;

(4) Thiazine-based compounds such as benzoylleucomethylene blue, p-nitrobenzoylleucomethylene blue and the like; (5) Spiro-based compounds such as 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3 -Benzyl spiro-
Dinaphthopyran, 3-methylnaphtho- (3-methoxy-
Benzo) -spiropyran and the like; and mixtures of these are utilized and selected depending on the desired properties depending on the application.

Examples of the heat-fusible substance include waxes such as paraffin, oxidized paraffin, polyethylene, oxidized polyethylene, stearamide, and castor wax.

Next, the thermosensitive coloring layer (C) containing a coloring agent will be described. The material and the manufacturing method can be obtained in exactly the same manner as the case of the lower sheet of the pressure sensitive paper. Activated clay, zinc salicylate, a resin having a phenolic hydroxyl group, and the like are preferably used as the coloring agent. These coloring agents are fixed to the support by the water-soluble or water-dispersible binder used when forming the above (A).

[0028]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Preparation of Thermosensitive Recording Layer (A) The following composition (a) and composition (b) were separately dispersed by a sand grinder, and the solution (a) according to the composition (a) and the solution (b) according to the composition (b) After obtaining and, (a) Liquid 130
Parts by weight, 190 parts by weight of (b) liquid, and 50 parts by weight of a 12% by weight aqueous solution of polyvinyl alcohol are mixed and stirred,
(C) A liquid was obtained.

Composition (a) Ferric stearate 20 parts by weight Aluminum hydroxide 20 parts by weight Polyvinyl alcohol: 12% by weight solution 40 parts by weight Water 50 parts by weight

Composition (b) Stearyl gallate 30 parts by weight Aluminum hydroxide 20 parts by weight Polyvinyl alcohol: 12% by weight solution 70 parts by weight Water 70 parts by weight

Next, after the liquid (c) for forming the thermosensitive coloring layer was prepared, it was coated on a substrate sheet (1) made of high-quality paper of 30 g / m 2 at a coating amount of 5 g (dry) / m 2. After processing, drying and calendering, a recording material having a thermosensitive coloring layer (A) on the base material sheet (1) having a Bekk smoothness of 500 seconds was obtained.

Preparation of a heat-fusible layer (B) containing a basic dye and a heat-fusible substance 10 g of 3-piperidino 6-methyl-7-anilinofluorane as a basic dye and 10 g of a heat-fusible substance Carbana wax 30g and stearic acid amide 15g 120
After melting at ˜130 ° C., at a temperature of 70 ° C. to 80 ° C., a coating amount of 3 g (dry) / m ^{2 is} applied to the back surface of the recording material having the thermosensitive coloring layer (A) on the above-mentioned substrate sheet (1). Paper (I) was obtained.

Preparation of Lower Paper (II) Having Thermosensitive Coloring Layer (C) Containing Coloring Agent on Surface 65 parts of aluminum hydroxide, 20 parts of zinc oxide, 3,5-
Mixture of zinc di (α-methylbenzyl) salicylate and α-methylstyrene / styrene copolymer (mixing / melting ratio 80 /
20) 15 parts, 5 parts of a 12% by weight polyvinyl alcohol aqueous solution (solid content) and 300 parts of water were crushed in a ball mill for 24 hours to obtain a dispersion liquid, and 20 parts of carboxy-modified styrene-butadiene copolymer latex (solid content). Was applied to a base material sheet (2) made of high-quality paper of 50 g / m ² at a coating amount of 5 g (dry) / m ² and dried to obtain a lower paper (II). Got

[Evaluation and Results] Thermal printer "DPU-412" manufactured by Seiko Denshi Kogyo Co., Ltd. from the thermal recording layer (A) side of thermal multiple copying paper in which upper paper (I) and lower paper (II) are superposed. Printing was performed. As a result, it was possible to obtain two sheets of high visibility and high visibility at the same time by printing once.

[0035]

EFFECTS OF THE INVENTION The heat-sensitive multiplex copying paper of the present invention has high fastness in one printing and can obtain two highly visible records at the same time. It was found that the thermal recording material is highly practical and has a high utility value in the fields of heat-sensitive recording labels, handy terminals, and the like, for example, in applications that require unobtrusive recording.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a usage state of a heat-sensitive multiplex copy paper of the present invention.

[Explanation of symbols]

 (I): Recording sheet as upper sheet (II): Recording sheet as lower sheet (1): Base sheet of upper sheet (I) (2): Base sheet of lower sheet (II) (A) ): Thermosensitive recording layer of top paper (I) (B): Thermofusible layer of top paper (I) (C): Thermosensitive coloring layer of bottom paper (II)

Claims (2)

[Claims] 1. A base sheet (1) has a heat-sensitive recording layer (A) containing a ferric acid fatty acid salt and a chelating agent as main components on the surface, and a colorless or pale basic dye and a heat-sensitive recording layer on the back side. Top paper (I) having a heat-fusible layer (B) containing a fusible substance,
And a bottom paper (II) having a thermosensitive color developing layer (C) containing a coloring agent for coloring the basic dye on the surface of the substrate sheet (2). paper. 2. The heat-sensitive multiplex copying paper according to claim 1, wherein the chelating agent of the upper paper (I) is a polyhydric phenol and / or a dithiocarbamate.