JPH02155694A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To prevent the formation of a hole in a substrate or the cutting thereof even when a color material solution of a solvent system is applied on the substrate being poor in solvent resistance and thereby to enable the application of the color material solution without any problem by having a construction wherein a thermosetting resin layer is laminated on the substrate and then a color material layer is laminated on said layer. CONSTITUTION:A thermosetting resin layer is provided on a substrate and then a color material layer is provided on said layer. In the case when a hot-melt color material layer is formed by solvent coating on a substrate formed of a polymer being poor in solvent resistance, neither wrinkle nor cutting takes place on or in the substrate in the process of coating even when any ordinary solvent is used, and the coating can be performed without any problem. In a thermal transfer recording medium having the color material layer on one surface of the substrate, a thermal transfer recording medium of the present inventing has a construction wherein thermosetting resin is laminated on the substrate and then the color material layer is laminated on said resin. For the substrate, a well known film or paper can be used. As for the thermosetting resin, the resin obtained by making a self-crosslinking water resin emulsion or a water resin emulsion having a hydroxyl or carboxyl group react with a hydroxylic resin crosslinking agent is used.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a thermal transfer recording medium, which can be advantageously used in particular for color recording in office automation terminals such as facsimiles, printers, and copying machines, and for color recording of television images. The present invention relates to thermal transfer recording media.

(Prior art) Various methods are being considered for color recording, such as electrophotography, inkjet, and thermal transfer recording. It is advantageous over other methods in that it is inexpensive.

In the thermal transfer recording method, an image receptor is superimposed on the coloring layer surface of a thermal transfer recording medium in which a coloring material layer containing a coloring material is formed on a base material, and the coloring material layer is applied to the back side of the thermal transfer recording medium through a thermal head or an electric head. Recording is performed by heating the recording medium to transfer the coloring material in the thermal transfer recording medium to the image receptor. From the point of view of coloring materials, these methods include a melt-type transfer recording method using a heat-melting coloring material layer, and a coloring material layer containing a sublimable dye (
There is a sublimation transfer recording method using a heat-transferable coloring material layer.
In terms of heating means, a thermal head method and an energization method are known.

(Problems to be Solved by the Invention) In the above-mentioned thermal transfer recording medium, the heat-melting coloring material liquid is usually applied by the following three methods.

One is hot-melt coating, in which the colorant liquid is melted with heat to lower its viscosity and applied at high temperatures, and the other is solvent coating, in which the colorant liquid is applied by dissolving the colorant components in an appropriate organic solvent. The remaining seven are water-emulsion coach inflatables in which coloring components are dispersed in water and applied.

Hot-melt coating is the cheapest coating method as it does not require drying of the solvent and the manufacturing cost of the coating equipment is low. However, if the melt viscosity of the colorant liquid is high, it is necessary to control the coating thickness thinly. is difficult.

Water-emulsion Φ coatings do not present any particular problems during application, but in order to achieve stable dispersion, a surfactant must be used, and these surfactants often have a negative effect on the performance of the colorant. Can be seen. Another drawback is that water as a dispersion medium must be dried, resulting in high energy costs.

Solvent coating does not require any particular surfactant to dissolve and disperse the binder colorant, nor does water require any energy costs to dry the solvent. However, aromatic solvents such as toluene, ketone solvents such as methyl ethyl ketone and methyl imbutyl ketone, and ester solvents such as ethyl acetate and butyl acetate, which are commonly used in solvent coatings, do not have good solvent resistance as base materials. Polymers When using resin films such as polycarbonate, polyacrylate, polysulfone, polyethersulfone, etc., they attack the substrate, cause wrinkles, and eventually cause the substrate to break. Therefore, when using substrates made of the above-mentioned superior materials, coating is not possible.

In addition, in the case of the current-carrying method, a metal thin film layer may be provided between the heat-fusible colorant layers on the base material, but in that case, the color material liquid is applied directly onto the base material. However, during coating, the solvent may penetrate through defects in the metal thin film layer, amplifying scratches on the base material surface, creating holes in the base material, or in severe cases. for,
The base material may be cut. Further, even after coating, a part of the base material is eroded by the solvent that has penetrated into the thin metal layer, and a part of the thin metal film layer is peeled off and transferred during printing.

c) Means for Solving the Problems) As a result of intensive studies by the present inventors to solve the above problems, it was found that by providing a thermosetting resin layer and then a coloring material layer on the base material, solvent resistance can be improved. When coating a hot-melt coloring material layer on a substrate such as a polymer with poor quality, no matter what kind of solvent is used, the substrate may wrinkle or cut during coating. We have discovered that coating can be performed without any problems and have arrived at the present invention.

That is, the gist of the present invention is a thermal transfer recording medium having a coloring material layer on one side of a base material, which is characterized by having a structure in which a thermosetting resin layer and then a coloring material layer are laminated in contact with the base material. It exists in a thermal transfer recording medium.

, Hereinafter, the present invention will be explained in detail.

As the base material used in the present invention, conventionally known films and papers can be used.

For example, resin films with relatively good heat resistance such as polyester, nylon, and polyimide, glassine paper, and condenser paper are used, but the present invention is particularly applicable to resin films such as polycarbonate, polysulfone, and polyethersulfone, which have poor solvent resistance. It is effective when used as a base material. Moreover, the thickness of the base material is preferably 7 to 208 m. In the case of the current-carrying method, the base material is a film in which the above-mentioned resin isobarically conductive carbon or metal powder is kneaded, and then a method such as vacuum evaporation or sputtering is applied on top of the film.
A material provided with a metal thin film layer such as s A l or Cul N t is used.

In this case, the appropriate thickness of the base material is 3 to 30 μm, and the thickness of the metal thin film layer is 200 to 2000 Å.

Commercial products can also be used as films containing conductive carbon, such as Macrohole KLJ manufactured by Bayer AG, West Germany.
-100 (volume specific resistance O1 0, thickness/J-μr
rL).

As the thermosetting resin used in the present invention, a self-crosslinking aqueous resin emulsion or an aqueous resin emulsion having a hydroxyl group or a carboxyl group and a hydroxyl resin crosslinking agent are used. The self-crosslinking aqueous resin emulsion includes saturated copolymerized polyester resin, acrylic acid ester copolymerized resin, acrylic vinylidene chloride copolymerized resin, vinyl acetate acrylic copolymerized resin, acrylic tyrene copolymerized resin, and ethylene-vinyl acetate copolymerized resin. Modified products such as (for example, glycidyl etherification) are used. Water-based resin emulsions with hydroxyl or carboxyl groups include saturated copolyester resins, carboxy-modified styrene-butadiene copolymer resins, acrylic ester copolymers, etc. Water-soluble isocyanate resins, melamine resins, glyoxal resins, The thermosetting resin layer used in the present invention can be obtained by reacting with a crosslinking agent such as an epoxy resin.

The composition ratio of the resin emulsion to the crosslinking agent is preferably 2// to //3 in terms of the ratio of reactive groups. The self-crosslinking aqueous resin emulsion can be thermally cured alone or in combination with the above-mentioned water-soluble resin crosslinking agent. Further, as the thermosetting resin used in the present invention, the above-mentioned polyester type and acrylic type are excellent, and polyester type is particularly recommended.

These resin emulsions are coated in an aqueous dispersion system, then dried and hardened to form a thermosetting resin layer.

The dry coating thickness of the thermosetting resin is 0.02 to 70
μm Preferably 0.7 to g μm, more preferably 0
．． A range of 2 to 48 m is good. If the coating thickness is less than 0.0.2 μm, when a solvent-based coloring material is applied later, the solvent may pass through the film and attack the base material, causing holes or cutting of the base material. However, if it is thicker than 70 μm, heat transfer from the thermal print head during printing or from the resistive layer when energizing is slow, resulting in poor thermal efficiency, resulting in blurred printed images and an inability to increase printing speed. The negative effects of this can be seen.

Drying is carried out by heating at 0 to 100° C. for 10 to 20 seconds, followed by aging at 60° C. for 7 days and further at 120° C. for half a day, to achieve good hardening.

The heat-melting color material layer includes waxes such as paraffin wax, microcrystalline wax, and carnauba wax, thermoplastic resins such as ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate, and pigments such as carbon black. A coloring material such as a dye such as oil black is dissolved and dispersed in a suitable solvent such as toluene or methyl ethyl ketone, and is overcoated on the thermosetting resin layer. The dry thickness of the color material layer to be applied is 2 to gμm,
Preferably it is 3 to 2 μm.

The heat sublimable color material layer is made of polycarbonate, polysulfone,
A binder resin such as polyether sulfone, ethyl cellulose, polyarylate, etc. and a heat-sublimable colorant are dissolved and dispersed in a suitable solvent such as toluene, THF, dioxane, etc. It is overcoated on the curable resin layer. The dry thickness of the applied coloring material layer is 0.2 to 3 μm, preferably 0.3 to 3 μm.

The significance of providing a thermosetting resin layer on a base material and then a coloring material layer is that, in addition to preventing wrinkles and cutting of the base material when applying the coloring material, It also has the effect of increasing the adhesive strength between the layer and the base material and making it difficult for the colorant layer to peel off. In addition, in the case of an energization method in which a metal thin film layer is provided, there is also an effect of preventing a phenomenon in which a part of the metal thin film layer is peeled off and transferred together with the coloring material during printing.

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. In addition, in the examples, "part"
indicates "parts by weight".

Example 1 Thermosetting polyester emulsion Bess Resin A-2/Yo/G (manufactured by Takamatsu Yushi ■) was coated onto a 6μ polycarbonate film by reverse gravure so that the dry film thickness was 0 μm.

After coating, the film was wound up and cured at 20'C for 7 hours.

Next, 2# of a mixture of alkyl alcohols having 30 to 36 carbon atoms was mixed with tolylene diisocyanate/zO? while stirring in a reaction pot heated to io0°C. was added dropwise, and after reacting for 5 hours, the product was taken out and used to obtain a color material liquid having the following composition.

Heat-melting coloring material layer composition This coloring material liquid was applied onto the previous thermosetting resin layer using a gravure coater at a coating speed of /Om/min so that the dry thickness was ≠ μm. The film could be coated without any problems without wrinkles or cutting. This recording medium was installed in a thermal printer (prototype device equipped with a thin film type line thermal head with a heating element density of ♂dots/mm), and O1/W/dot, 7m.
When printed on plain paper with a pulse width of 5 ec, a clear printed image without background stains was obtained. We also tested the peeling resistance of the coloring material layer by hand-rolling this recording medium.
Good results were obtained.

Comparative Example 1 A color material liquid having the exact same composition as in Example 1 was applied to a 6μ polycarbonate film using a gravure coater without providing a thermosetting resin layer. As a result, the film was wrinkled and frequently cut, making it difficult to coat the film properly.

Example Conductive polycarbonate film manufactured by Bayer, West Germany (trade name: Macrohole KLj-1009, thickness: 1 μm)
) was vacuum-deposited with AI to a thickness of 1000A, and a coating liquid having the following composition was further applied thereon so that the dry film thickness was O0≠μm.

After coating the thermosetting resin layer, the wound film was cured in a TO'C oven, and then further cured in an oven at ixo℃ for 7 days.
Allowed to cure for hours.

Next, two mixtures of alkyl alcohols having a carbon number of 34t to ≠0 and tolylene diisocyanate 2002 were added to Example/
Using the reaction product produced in the same manner as above, a color material liquid having the following composition was obtained.

Composition of heat-melting coloring material layer This coloring material liquid was applied onto the previous thermosetting resin layer using a gravure coater at a coating speed of 3.0 m/min and a dry thickness of 3.
Where the film was coated in such a way that it became even μm, the scratches on the film were amplified.
There were no holes or cuts, and the coating could be applied without any problems.

Furthermore, when this recording medium was slit into ribbons and printed using an IBM Quiet Writer, the color material layer did not peel off, and clear alphabets without background stains could be printed.

Comparative Example 2 A conductive polycarbonate film (Macrohole KL3-100,
A color material liquid having the same composition as in Example 1 was applied onto the AI vapor-deposited layer using a gravure coater at a coating speed of 2 evenings (H/nin, 758 m thick) without providing a thermosetting resin layer.
When the film was coated to a dry thickness of 3.3 μm, the scratches that were originally on the film were clearly amplified, and the film was cut during the coating process. Next, when this recording medium was slit into a ribbon shape and printed using an IBM Quiet Lighter, clear printing with no background smudges was achieved. Some peeling was observed.

Example 3 In the same manner as in Example 3, a coating liquid with the following composition was applied to a conductive polycarbonate film (Macrohole K L 3-/00, thickness 758 m) on which AI was vacuum-deposited to a thickness of 10OOA to a dry film thickness of O9≠ It was coated to a thickness of μm.

After curing the thermosetting resin layer for one day, it was further cured in an oven at ISO℃ for 2 days.
It was allowed to cure for 0.1 minute.

Next, a magenta heat-sublimable coloring material layer was obtained using a sublimable dye having the following structural formula.

Composition of heat sublimable coloring material layer This coloring material liquid was applied onto the previous thermosetting resin layer using a gravure coater at a coating speed of 10 m/min to a dry thickness of 0. There was no amplification of scratches, holes, or cuts, and the coating could be applied without any problems. Further, this recording medium was slit onto a ribbon, and the image receiving paper having a color developing layer containing polyester resin and fine silica on the surface was printed using a Sharp electric printer WD-
When printing using 02HP, the coloring material layer did not peel off,
It was possible to print clear characters without background smudges.

(Effects of the Invention) As explained above, according to the present invention, even when a solvent-based coloring liquid is applied onto a substrate with poor solvent resistance, there is no problem in that the substrate is not punctured or cut. It is possible to provide an excellent heat-sensitive transfer recording medium on which a coloring material liquid can be applied and the coloring material layer has good peeling resistance. Therefore, the present invention is extremely useful industrially.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of the thermal transfer recording medium of the present invention, and FIGS. 2 and 3 are schematic cross-sectional views in the thickness direction of the electrically conductive thermal transfer recording medium of the present invention. Thermal print head base material Thermosetting resin layer Heat melting coloring material layer or heat sublimation coloring material layer Recording electrode resistance layer Return electrode metal thin film layer

Claims (1)

[Claims] (1) A thermal transfer recording medium having a coloring material layer on one side of a base material, characterized in that the thermal transfer recording medium has a structure in which a thermosetting resin layer and then a coloring material layer are laminated in contact with the base material.