JPH0419189A - Thermal transfer recording medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal transfer recording medium used in a color recording device using a thermal transfer method.

[Prior Art] Thermal transfer recording media used in conventional thermal transfer printers are
In order to transfer ink sharply and reproducibly to the transfer target during thermal transfer, we select a binder that instantly melts and reduces viscosity at a certain temperature, and then add coloring materials such as pigments and dyes to it and disperse it. The heat-melting ink is processed to become a heat-melting ink, and the heat-melting ink is coated onto a base material in a uniform film thickness, or as in Patent Bg59-224389, the thickening of the ink and prevention of ink connections are prevented. Therefore, the heat-melting ink was applied in a dotted manner.

[Problems to be Solved by the Invention] However, with the thermal transfer recording medium of the prior art described above, when a full-color image consisting of three colors of yellow, magenta, and cyan is printed using a high-resolution thermal head, the ink runs out. As a result, gradation characteristics deteriorate due to a density jump from medium density to high density, resulting in a narrow color expression range and an unclear image.

Even if the shape of the ink is dotted to improve ink cutting, if the area of each individual ink is large, or if the ink is crushed and deformed during transfer, the dots may not form with each other. Good gradation could not be obtained due to connections, ink flow, etc.

Therefore, the purpose of the present invention is to prevent density jumps, ink flow, etc. when printing high-resolution color images, improve ink gradation characteristics, and obtain clear images with a wide color reproduction range. An object of the present invention is to provide a thermal transfer recording medium that can be

[Means for Solving the Problems] The thermal transfer recording medium of the present invention has colored particles each having a diameter of 20 μm or less independently coated on a base material, and each colored body having a diameter of 20 μm or less is independently coated on a base material. The method is characterized in that the applied particulate colored material is transferred onto the transfer target without changing its shape.

[Function] According to the thermal transfer recording medium of the present invention having the above-mentioned characteristics, it is possible to prevent ink connections, flows, etc. when printing high-resolution color images, and it has excellent gradation characteristics from low density to high density. A clear image with a wide color reproduction range can be obtained.

[Example 1 The present invention will be specifically explained below using Examples and Comparative Examples.

FIG. 1 schematically shows the concept of the structure of the thermal transfer recording medium of the present invention.

The thermal transfer recording medium shown in FIG. 1 is constructed by coating a support 2 with colored particles 3 prepared in the form of fine particles at a density that allows each particle to be independent.

The particle size is preferably 20μ or less, more preferably 5μ or less.

The particles can be fixed onto the support by melt-bonding some of the particles onto the support, or by coating the surface of the particles with a material capable of melt-bonding or other adhesive action. The material fixes the particles to the support, or fixes them by strengthening the affinity between the particle's surface properties and the support's surface properties, or by providing an adhesive layer on the support and adhering the particles to it. There are ways to fix it.

The coating density of particles is preferably as small as the distance between particles.
It is desirably smaller than the diameter of the particles, and as long as there is no interaction between the particles, they may be partially in contact with each other.

The form of particle application may be either regular or irregular, but it may be preferable to be irregular in order to avoid interference with head density and signal density.

FIG. 2 schematically shows the concept of the transfer mechanism of the thermal transfer recording medium of the present invention.

As shown in FIG. 2, the thermal transfer recording medium 1 is superimposed on the transfer target 6 directly under the thermal head 7, and heat generation according to a signal and pressure necessary for transfer are applied on the platen 8.

4 in the figure is a particulate colored body transferred from the thermal transfer recording medium 1, and 5 indicates the original position of the colored body. As shown in the figure, the relative positions of the particles do not change when they are coated on the support and when they are transferred onto the transfer target. Further, even if some distortion or crushing occurs in the shape of the particles, changes in shape such as cracking or cohesive failure of the particles do not occur.

Particulate colored materials that can be used in the thermal transfer recording medium of the present invention include PMMA, EVA, EEA, polystyrene, methacrylate, axolate, divinyl, fluorine polymer, colloidal silica, polyurethane, polyester, and silicone. , polymers such as polyvinyl, melamine resin, polyamide, alkyd resin, polyamide, phenol resin, waxes and pigments such as carnauba wax, paraffin wax, oxidized wax, synthetic wax, animal and vegetable wax, petroleum wax, etc. It may be a mixture of coloring materials such as dyes and carbon black, or it may be particles made of the coloring material itself or a mixture of the coloring material and the resin wax described above and coated with the above-mentioned materials.

The method for producing the thermal transfer recording medium of the present invention involves coating a support with an emulsion of colored particles or dispersing them in a specific solvent using a surfactant, and then evaporating the solvent. or a method in which the particles or a dispersion of the particles are applied onto a support provided with an adhesive layer and the particles are fixed on the adhesive layer. , the colored particles in the form of fine particles are charged, and the particles are attached to the support by electrostatic attraction with the support;
Thereafter, the particles are fixed on the support by heating, pressure, an adhesive layer or other methods, or the colored particles are made into a mist and sprayed onto the support, and then the particles are fixed by heating, pressure, an adhesive layer, etc. There are ways to fix it.

Table 1 shows the composition and size of the particulate colored bodies used in this example.

Table 1 The colored bodies in the form of fine particles were prepared according to the following procedure. First, the composition in the table above is hot-melt kneaded, and the binder is
After confirming uniform dispersion and mixing of the coloring material, fine particles with a particle size of 3 μm were prepared to obtain a particulate colored body.

The method for producing the particulate colored body of the present invention is not limited to the above-mentioned method, but can also be produced by an emulsion method, a microcapsule method, or the like.

FIG. 3 shows the structure of a thermal transfer recording medium according to Example 1 of the present invention.

Example 1 was obtained by heat-treating the particles that were individually coated on a support to melt only the surface of the particles and impart adhesiveness to the surface of the particles, thereby fixing the particles on the support. This is a thermal transfer recording medium.

FIG. 4 shows the structure of a thermal transfer recording medium according to Example 2 of the present invention.

In Example 2, colored particles whose surfaces are coated with heat-melting adhesive are individually coated onto a support, and then heat-treated to impart adhesiveness to the particle surface, thereby forming particles onto the support. This is a thermal transfer recording medium obtained by fixing.

This time, the material used as a surface coating agent for particles is a mixture of paraffin wax and EVA resin, but it is not limited to these materials.

FIG. 5 shows the structure of a thermal transfer recording medium according to Example 3 of the present invention.

In Example 3, an acrylic resin-based adhesive layer was coated on the surface of the support, and colored particles were independently applied to the surface.
This is a thermal transfer recording medium obtained by fixing particles on a support.

FIG. 6 shows the structure of a thermal transfer recording medium according to a comparative example of the present invention.

As shown in the figure, the thermal transfer recording medium of the comparative example has a structure in which a heat-melting wax-based ink is coated on a support in a layered manner.

When creating a color image, the thermal transfer recording medium of the present invention can be used to create a monochromatic thermal transfer recording medium as shown in FIG. 8 even if a plurality of inks are coated on the same substrate as shown in FIG. A configuration having a plurality of them may also be used.

Next, a printing test was conducted using the above thermal transfer recording medium. In the printing test, three-color overlapping printing was performed using a line type thermal head having a heating element density of 300 DPI.

The print pattern was a density gradation pattern of 16 horizontal stripes on smooth paper. Adjust the printing energy so that the 14th gradation is at full density when the first color is transferred,
A constant value was set so that excess energy was applied to gradations of 15 and above. Next, as an evaluation of transferability, the transfer density for each gradation was measured using Ma
The reflection OD value was measured using cb et h -T R-927 using a complementary color filter.

The evaluation results of gradation of the present example and comparative example are shown below. In the figures below, the vertical axis represents the reflection OD normalized to the maximum OD value of 1.0, and the horizontal axis represents the transfer energy.

FIG. 9 shows the gradation of magenta, the first color, in Examples 1 to 3 and a comparative example.

FIG. 10 shows the gradation of the second color cyan in Examples 1 to 3 and the comparative example.

FIG. 11 shows the gradation of the third color yellow in Examples 1 to 3 and the comparative example.

As shown in FIGS. 9 to 11, the thermal transfer recording media of Examples 1 to 3 have excellent gradation from the low printing energy range to the high printing energy range, and can be applied with high printing energy. No ink flow phenomenon occurred even in the high concentration range.

On the other hand, in the thermal transfer recording medium of the comparative example, in addition to poor ink transfer performance in the low density range, there was a rapid increase in density from medium density to high density, and furthermore, the ink flow phenomenon occurred in the high density range. It has happened.

Next, using the four types of thermal transfer inks mentioned above, 64
As a result of printing a full-color image by superimposing three-color gradation transfer, the images using the thermal transfer recording media of Examples 1 to 3 had a wide range of color expression, and smooth and clear images were obtained.

In addition, the image produced using the thermal transfer recording medium of the comparative example had a narrow color expression range, and image quality deterioration phenomena such as roughness due to density jumps, ink flow, and insufficient density were observed.

From the above results, in order to prevent density jumps, ink flow, etc. when printing high-resolution color images, improve ink gradation characteristics, and obtain clear images with a wide color reproduction range, It is preferable to use the thermal transfer recording medium of the present invention.

The thermal transfer recording medium of the present invention is not limited to the thermal transfer method using a line type thermal head as in the embodiment, but can also be applied to a serial type thermal transfer method, an electrically conductive thermal transfer method, and other thermal transfer methods.

Furthermore, in this embodiment, three colors of yellow, magenta, and cyan are used.
Although a color image composed of colors has been described, the present invention is not limited to this, and the present invention is not limited to this.
It is also possible to apply the present invention to color printers, monochrome printers, and two-color printers.

[Effect of the invention 1 As explained above, by using the thermal transfer recording medium of the present invention, when printing a high-resolution full-color image, good gradation can be obtained in all density ranges, and clear and color expression can be achieved. This has the effect of providing a wide range of high image quality.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the structure of the thermal transfer recording medium of the present invention. FIG. 2 is a schematic diagram showing the transfer principle of the thermal transfer recording medium of the present invention. FIG. 3 is a sectional view showing the structure of a thermal transfer recording medium according to Example 1 of the present invention. FIG. 4 is a sectional view showing the structure of a thermal transfer recording medium according to Example 2 of the present invention. FIG. 5 is a sectional view showing the structure of a thermal transfer recording medium according to Example 3 of the present invention. FIG. 6 is a sectional view showing the structure of a thermal transfer recording medium according to a comparative example of the present invention. FIG. 7 is a schematic diagram showing the configuration of a transfer mechanism using a thermal transfer recording medium having multiple colors according to the present invention. FIG. 8 is a schematic diagram showing the configuration of a transfer mechanism using the monochromatic thermal transfer recording medium of the present invention. FIG. 9 is a correlation diagram between printing energy and transfer density showing the gradation of magenta, the first color, of thermal transfer recording media of Examples and Comparative Examples of the present invention. FIG. 10 is a correlation diagram between printing energy and transfer density showing the gradation of cyan, the second color, of the thermal transfer recording media of Examples and Comparative Examples of the present invention. FIG. 11 is a correlation diagram between printing energy and transfer density showing the gradation of the third color yellow in Examples and Comparative Examples of the present invention. 1 ・ 2 ・ 3 ・ 4 ・ 5 ・ 6 ・ 7 ・ 8 ・ 9 Adhesive layer for coating / Adhesive layer for fixing particles / Hot-melt ink layer Fig. 3 Fig. 4 Fig. 5 Fig. 1 (Q)

Claims (2)

[Claims] (1) A thermal transfer recording medium characterized in that colored particles each having a diameter of 20 μm or less are independently coated on a base material. (2) The thermal transfer recording medium according to claim 1, wherein the particulate colored bodies individually coated on the base material are transferred onto the transfer target without changing the shape thereof.