JP2965925B2 - Thermal recording medium using sublimable dye - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive material which is heated by a thermal head or the like to form a color at a portion of the heat-sensitive material to form an image record. The present invention relates to a thermosensitive recording medium having excellent heat resistance.

[0002]

2. Description of the Related Art A thermosensitive recording paper is provided on a support, which is provided with a thermosensitive coloring layer comprising a colorless or pale-colored leuco dye and an organic color developer, and the surface thereof is heated and melt-colored by a thermal head or the like to form an image record. But, JP 43-4160, JP 45-
It is widely known as 14039. Such heat-sensitive recording paper is widely used as a recording material for facsimile and the like, and as a word processor paper. However, this type of heat-sensitive recording paper has a serious drawback in that the obtained image record gradually becomes thinner and, in severe cases, the record disappears. Furthermore, when a very weak pressure is applied during handling, especially when rubbed, there is a disadvantage that the portion develops color due to the frictional heat, and the reliability of the obtained image recording is extremely low. At present, the use of thermosensitive recording paper is extremely limited.

On the other hand, other heat-sensitive recording materials include pigments,
A thermosensitive recording layer made of a heat-meltable wax, thermoplastic resin, etc. is provided on a thin polyester film, and this is combined with another facing recording paper. The heat of the thermal head transfers the thermosensitive recording layer to the recording paper to record images. Thermal transfer materials for obtaining the above are widely known, for example, from JP-B-58-13359 and JP-B-01-46319. This type of heat-sensitive recording material is extremely excellent in image recording stability and preservability due to the use of a pigment, but because the recording layer on the film is transferred to recording paper such as high quality paper combined with this. In addition to the disadvantage that the two materials of the thermal transfer film and the high-quality paper are always required and the cost is high, the transferred image remains on the transfer film, which is not desirable from the viewpoint of maintaining security.

Further, there is known a sublimable dye-transfer thermosensitive recording material described in, for example, JP-B-03-80116, which uses a sublimable dye instead of a pigment. Polyester, a thermosensitive recording material in which a sublimable dye layer is provided on a thin support such as paper, and a polyester layer on which the sublimable dye is dyed is provided on the surface of another sheet facing the sublimation dye, wherein the pigment layer is Instead of the transfer, the sublimable dye sublimates by heating, moves to the opposite resin surface, and dyes to form an image record. These thermosensitive recording materials, like pigment-based transfer thermosensitive recording materials, are not only extremely expensive because they always use two types of recording materials, but also discard the donor film coated with a sublimable dye after use. This has the disadvantage that the operation is extremely complicated.

[0005]

SUMMARY OF THE INVENTION The present invention is intended to simply and easily obtain a thermal image record on the same paper surface instead of a transfer image. There is no serious drawback that the record will be lost if it becomes thin and in extreme cases, it is extremely excellent in storability,
When a very weak pressure is applied during handling, especially when rubbed, there is no defect that the portion develops color due to the frictional heat, and the reliability for image recording is extremely high, and its use Is not limited thereto.

[0006]

Generally, sublimable dyes are not colorless or light-colored but are all colored. When a layer containing this sublimable dye is provided on a recording paper, a conventional heat-sensitive recording paper is used. It was extremely difficult to obtain a recording paper having a white surface as described above. However, the present inventors have conducted intensive studies on this, and as a result, by providing a layer containing a thermoplastic resin and titanium oxide to be dyed with the sublimable dye on the layer of the sublimable dye, It has been found that a heat-sensitive recording medium having an external appearance surface, and a portion which is sharply colored by heating with a thermal head or the like, and which is robust and extremely excellent in storability can be obtained.

That is, the present invention relates to a polyester resin formed by forming a sublimable dye layer (2) containing a sublimable dye on a support (1) and then dyeing the sublimable dye layer on the sublimable dye layer with the sublimable dye. Particles and titanium oxide particles in a weight ratio of 1: 1 to 1
The present invention relates to a heat-sensitive recording material characterized by being contained at a ratio of 1: 5.

This type of thermosensitive recording medium does not have any coloring stains caused by friction seen in conventional thermosensitive paper, and the recorded image is stable and has no tendency to disappear. Furthermore, as in the case of transfer thermosensitive recording materials, there is no need to combine two types of recording materials, a donor transfer film and a recording paper, and use them in a superimposed manner. Can be obtained.

The structure and operation of the present invention will be described with reference to FIG. The thermosensitive recording medium 4 of the present invention comprises a support 1, a sublimable dye layer 2, and a sublimable dye fixing layer 3. When a sublimable dye or a sublimable dye layer 2 composed of a sublimable dye and a binder provided on a support 1 is partially heated by a thermal head 6 or the like, the sublimable dye at that portion sublimates and is overlaid thereon. The process proceeds to the sublimable dye fixing layer 3 provided. The sublimable dye fixing layer 3 is made of a thermoplastic resin, titanium oxide, and other inorganic pigments dyed according to the amount of the sublimable dye.
It is composed of a binder and captures and fixes the sublimable dye that has been sublimated by heating. The sublimable dye fixing layer 3 also has the function of concealing the color tone of the sublimable dye in the lower layer by titanium oxide, resin particles and other inorganic pigments contained in the layer at the same time. The resin particles are easily softened by heating, and the fixing layer is partially transparentized. At the same time, the resin particles are easily and uniformly dyed by the sublimed dye, thereby forming the thermal image record 5 having excellent resolving power and storage stability. At the same time, the fixing layer 3 has a function as a protective layer for the sublimable dye, and plays a role of completely preventing coloring of the recording medium due to friction during handling.

The sublimable dye used in the present invention includes:
A dye that sublimates or vaporizes at 50 ° C. or higher, mainly a disperse dye, a thermal transfer recording material such as an oil-soluble dye, a sublimable dye used for thermal transfer printing, and the like, for example, CI Disperse Yellow 1, 3, 8, 9, 16, 41, 54, 60, 77, 116, etc .;
I. Disperse threads 1, 4, 6, 11, 15, 17, 55, 5
9, 60, 73, 83, etc .; CI Disperse Blue 3, 14, 1
9, 26, 55, 60, 64, 72, 99, 108 etc .; CI Solvent Yellow 77, 116 etc .; CI Solvent Red 23, 25, 2
7 etc .; CI Solvent Blue 36, 83, 105 etc. can be used. Naturally, these sublimable dyes can be used alone or as a mixture of two or more of them for adjusting the color tone.

The sublimable dye layer 2 comprises a solvent such as toluene, hexane, methyl ethyl ketone,
Ethyl acetate, methyl alcohol, dissolved or finely dispersed in ethyl alcohol, etc., binders such as polyvinyl chloride, polyvinyl acetate, polyvinyl butyral, cellulose acetate butyrate, polyamide, polyacrylate,
Polystyrene, natural rubber, synthetic rubber, or the like, or a mixture of two or more of these, and if necessary, an inorganic pigment is added, and the mixture is solvent-coated on a support and dried. Further, a sublimable dye may be finely dispersed in an aqueous solution and applied together with an aqueous binder such as polyvinyl alcohol, styrene-butadiene latex, and acrylate emulsion.

The sublimable dye layer 2 is generally formed by applying the above-described sublimable dye solution or dispersion onto a film or thin high-quality paper as a support by a method such as a wire bar, an air knife, a roll, or a gravure screen coating. Later, it is dried. The coating amount of the sublimation dye is generally from about 0.05-5 g / m ² in dry weight, preferably 2.0 to 3.0 g / m ²
It is.

As the support 1, ordinary high-quality paper, condenser paper, polyester film, polyethylene naphthalate film, porsulfone film, polyimide film, cellophane and the like are used. Desirably, it is ordinary high-quality paper, coated paper, or polyester film. Also, if necessary, to prevent penetration of the sublimable dye into the support, or to improve the adhesion of the sublimable dye layer, use a water-soluble or organic solvent-soluble resin to coat the undercoat anchor coat layer. May be formed.

As the resin to be dyed with the sublimable dye used for the sublimable dye fixing layer 3, various commonly available thermoplastic resins can be used, but polyester resins are particularly preferable from the viewpoint of dyeing properties. Is preferred. In the sublimable dye-fixing layer, these resins exist in the form of finely dispersed particles. However, it is particularly advantageous that the surface area is large in terms of capturing the sublimable dye,
Preferably, a polyester resin dispersion liquid dispersed in fine particles is used. Furthermore, in order to easily capture and dye the sublimable dye sublimated from the sublimable dye layer 2 at the bottom,
It is preferred that the resin be easily softened by the heat of the thermal head, and a polyester resin having a relatively low molecular weight is particularly desirable. Preferred examples have a particle size of 10 μm or less, and 1
It is particularly preferable to form the sublimable dye fixing layer of the present invention using a dispersion of a polyester resin having a glass transition temperature and a melting point of not higher than 00 ° C. Various polyester dispersions are commercially available as polyester resin dispersions suitable for this purpose. For example, there is an aqueous polyester dispersion (trade name: Polyester) manufactured by Nippon Synthetic Chemical Co., Ltd. This aqueous polyester dispersion is a 20% dispersion of a polyester resin having a glass transition temperature of 57 ° C. and has a particle size of about 5 μm.

The titanium oxide used in the present invention is used for the purpose of concealing the colored sublimable dye contained in the first layer and obtaining a thermosensitive recording medium having a white surface. Any commercially available anatase or rutile type titanium oxide can be used. Generally, titanium oxide has a particle size of about 0.2 to 0.5 μm, but it is particularly desirable that the titanium oxide has a particle size in the range of 0.2 to 0.5 μm. The ratio of the sublimable dye fixing resin to titanium oxide is generally in the range of 1: 1 to 1: 5, particularly preferably in the range of 1: 2 to 1: 3 by weight.

If necessary, an inorganic pigment other than titanium oxide may be used in the dye fixing layer. Since the surface of the sublimable dye fixing layer is heated by directly contacting the thermal head, a so-called sticking may cause an instantaneous adhesion phenomenon due to the melting and cooling between the thermal head and the surface of the recording medium. Generally, this phenomenon occurs remarkably in a normal thermosensitive recording medium, but an inorganic pigment other than titanium oxide may be used for the purpose of preventing this phenomenon. As this kind of inorganic pigment, inorganic pigments usually used in the field of paper processing,
For example, clay, talc, silica, magnesium carbonate, alumina, aluminum hydroxide, magnesium hydroxide, barium sulfate, kaolin, zinc oxide, calcium carbonate, aluminum oxide and the like can be used.

Further, in the present invention, it is particularly preferable that the fixing resin such as a polyester resin is heated and melted by heating with a thermal head or the like, and the sublimable dye fixing layer in that portion is made transparent. It is particularly preferable to use crystalline fine powder silica manufactured and sold under the trade name of Aerosil (manufactured by Nippon Aerosil Co., Ltd.).

Titanium oxide, an inorganic pigment, and / or aerosil are added to an aqueous solution in which a binder is dissolved, finely dispersed by an attritor or the like, and thereafter, an aqueous polyester dispersion is added and stirred to obtain a sublimable dye fixing solution. Is prepared. As the binder, all ordinary water-soluble resins such as polyvinyl alcohol, polyacrylamide, starch, gelatin, methylcellulose, polyvinylpyrrolidone and the like can be used in addition to the polyester resin, but polyester is preferably used. The obtained coating liquid is applied on the previously applied sublimation dye layer by wire bar, air knife, roll, gravure screen coating,
dry. The application amount of the sublimable dye fixing layer is about 1 g /
m ² range to 10 g / m ² are preferred, particularly preferably 3 g / m ² ~
It is in the range of 5 g / m ² .

Further, in the present invention, the sensitizing heat energy sensitivity can be adjusted by using a sensitizer (a heat-fusible substance) used for the leuco dye thermal paper. The sensitizer used for the leuco dye thermal paper includes dibenzyl oxalate,
Stearic acid amide, stearic acid methylenebisamide, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 4,4'-butylidenebis (6-t-butyl-3-methylphenol), 4,4 ' Many substances are already known, such as -ethylenedioxy-bis-benzoic acid diphenyl ester, and these substances can be appropriately selected and used.
No. 431, Japanese Unexamined Patent Application Publication No. 2-9680, Japanese Unexamined Patent Application Publication No. 2-1362, and numerous examples are disclosed in Japanese Patent Publication No. 51-37542.
The description is quoted here.

These sensitizers are added to the sublimable dye layer (2) and / or
Alternatively, fine particles can be contained in the sublimable dye-fixing layer (3), and by appropriately selecting the type and amount thereof, the temperature at which sublimation and fixing and color formation can be controlled.

[0021]

The present invention will be described more specifically with reference to the following examples.

Example 1 (a) Sublimable dye layer coating solution having the following composition; and (b)
A coating solution for a sublimable dye fixing layer was prepared. On the base paper of 40g / m ²
Using a 0.15 mm wire bar, the solution (a) was applied as the first layer, and dried by applying hot air. Next, after sufficiently drying, the liquid (b) was layered thereon as a second layer, and the liquid was similarly applied using a 0.25 mm wire bar, and dried to obtain a thermosensitive recording material that developed yellow. (a) Sublimation dye layer coating liquid weight part toluene 400 methyl ethyl ketone 400 Denka vinyl # 1000AKT (Note 1) 100 Kaya set Yellow-AG (Note 2) 40 Aerosil # 200 (Note 3) 30 (b) Sublimation dye fixing Layer coating liquid by weight aqueous polyester resin (Note 4) 700 Titanium oxide 300 Aerosil # 200 20

Example 2 The following coating liquid was prepared, and the same operation as in Example 1 was performed to obtain a thermosensitive recording medium that developed a blue color. (a) Sublimation dye layer coating liquid weight part toluene 400 Methyl ethyl ketone 400 Denka vinyl # 1000AKT 100 Kaya set Blue-FR (Note 5) 40 Dibenzyl oxalate 20 Aerosil # 200 30 Titanium oxide 20 (b) Sublimation dye fixing layer Coating liquid parts by weight Aqueous polyester resin 700 Titanium oxide 300 Aerosil # 200 20

Example 3 The following coating solution was prepared, and the same operation as in Example 1 was performed to obtain a thermosensitive recording medium that developed a red color. (a) Parts by weight of sublimation dye layer coating liquid Toluene 400 methyl ethyl ketone 400 Denka vinyl # 1000AKT 100 MS Magenta VP (Note 6) 40 Aerosil # 200 30 Titanium oxide 20 (b) Parts by weight of sublimation dye fixing layer coating liquid Aqueous polyester resin 700 Stearamide 40 Titanium oxide 300 Aerosil # 200 20

(Note 1) Denka vinyl # 1000AKT; manufactured by Denki Kagaku Kogyo Co., Ltd., polyvinyl resin (Note 2) Kayaset Yellow-AG; manufactured by Nippon Kayaku Co., Ltd.
Yellow sublimable dye (Note 3) Aerosil # 200; Nippon Aerosil Co., Ltd., fine powdered silica (Note 4) Aqueous polyester resin; Nippon Synthetic Chemical Co., Ltd., 20% aqueous solution (Note 5) Kayaset Blue-FR; Nippon Kagaku Made by Yakuhin Co., Ltd.
Blue sublimation dye (Note 6) MS magenta VP; Mitsui Toatsu Dye Co., Ltd., red sublimation dye

[0026]

According to the first embodiment, the color is yellow, and in the second embodiment, the color is blue.
In Example 3, a clear red heat-sensitive record could be obtained by the thermal printer PW-PR01-02 manufactured by NEC Corporation. Furthermore, the obtained recorded image was excellent in storability without being changed even with the passage of time, and no color was formed even when the surface of the recorded material was rubbed with a nail or the like.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a thermosensitive recording medium according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Support 2 ... Sublimation dye layer 3 ... Sublimation dye fixing layer 4 ... Thermal recording medium 5 ... Recorded image 6 ... Thermal head

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-286270 (JP, A) JP-A-7-228062 (JP, A) JP-A-63-71389 (JP, A) JP-A-2- 229084 (JP, A) JP-A-61-139490 (JP, A) JP-A-7-276833 (JP, A) JP-A-61-217291 (JP, A) JP-A-2-80288 (JP, A) JP-A-4-347691 (JP, A) JP-A-59-106997 (JP, A) JP-B-48-39183 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41M 5/26-5/38

Claims (4)

(57) [Claims] 1. A sublimable dye layer (2) containing a sublimable dye is formed on a support (1), and then polyester resin particles and titanium oxide to be dyed with the sublimable dye on the sublimable dye layer. A thermosensitive recording medium comprising particles in a weight ratio of 1: 1 to 1: 5. 2. The heat-sensitive recording material according to claim 1, wherein said sublimable dye layer (2) further contains a sensitizer. 3. The thermosensitive recording medium according to claim 1, wherein said sublimable dye fixing layer further contains a sensitizer. 4. The thermosensitive recording medium according to claim 1, wherein said support (1) is a paper or a polyester film.