JPS6341187A - Thermal transfer ink sheet - Google Patents

Abstract

PURPOSE:To obtain a homogeneous low density recording image having no density irregularity by lowering the melt viscosity of an ink component due to low energy heating, by adding a proper amount of non-drying oil to the ink component constituting a heat-meltable ink layer. CONSTITUTION:Non-drying oil is added to the ink component consisting of a coloring material and a low m.p. wax material in the heat-meltable ink layer 23 provided on a sheet base material 21 through an intermediate adhesive layer 22 in an amount of 2-60% by wt. of the ink component to lower the melt viscosity of the ink component. Since non-drying oil is added to the ink component consisting of the coloring material and the low m.p. wax material in an amount of 2-60% by wt. of the ink component, the melt viscosity of the ink component due to low energy heating can be lowered. Therefore, at the time of low density transfer recording caused by low energy heating, a homogeneous low density recording image having no density irregularity can be obtained. Further, by the low viscosity effect of the ink component, sensitivity to transfer density is enhanced.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a thermal transfer ink sheet for halftone recording used in thermal transfer printers and facsimile machines using thermal heads, in which a coloring material constituting a heat-melting ink layer and a low melting point are used. The composition is made by adding a non-drying oil such as castor oil to the ink component made of wax material, which lowers the melt viscosity of the ink component by low energy heating. This allows a uniform low-density recorded image to be obtained.

[Industrial application field]

The present invention relates to a thermal transfer ink sheet for intermediate density recording that can be repeatedly transferred and is used in thermal transfer recording type printers and facsimile machines using thermal heads, and is particularly capable of recording homogeneous transfer images from low to high density. The present invention relates to a thermal transfer ink sheet.

One of the recording methods for thermal printers and facsimiles is a thermal transfer recording method using a thermal head. This is done by pressing a thermal head through a thermal transfer ink sheet provided with a thermo/8 fusible ink layer onto a recording paper such as plain paper, such as commonly used high-quality paper, which is guided by a platen or the like. A plurality of heat generating parts of a thermal head are selectively made to generate heat based on print information, and molten ink is transferred onto recording paper to perform recording.

Due to the diversification of recorded information, the thermal transfer ink sheets described above are required to be capable of recording transferred images from low to high density, but density unevenness is particularly likely to occur in low-density transferred recorded images. Therefore, there is a need for a thermal transfer ink sheet for halftone recording that can record low-density transferred images without such 7% degree unevenness.

[Conventional technology]

As shown in FIG. 3, the conventional thermal transfer ink sheet for halftone recording has a structure in which Kayascent black is applied as a coloring material onto a sheet base material 1 made of, for example, a polyester film, via an intermediate adhesive layer 2 made of polyester resin. (manufactured by Nippon Kayaku), fatty acid amide and paraffin wax as a low melting point wax material are mixed, and fine powder of carbon blank with excellent cohesiveness is further dispersed as a filling material, so-called solid fine powder. It has a structure in which a hot-melt ink layer 3 filled with an ink component consisting of the coloring material and a low melting point wax material that is solidified at room temperature is provided in the porous space of a porous stone wall structure made of a filled material. .

The thermal transfer ink sheet described above is produced by pressing a thermal bed onto one surface of the sheet base material with the heat-melting ink layer 3 stacked on the recording paper in a corresponding manner, and then applying the heat-melting ink to the recording paper using the heating element of the thermal bed. By selectively heating the ink layer 3, an appropriate amount of the melted ink component oozes out onto the surface of the ink layer 3, and is transferred onto the recording paper to perform recording.

At this time, by controlling the electric power for heat generating energy applied to the thermal head or the application time (applied pulse width), the melt transfer rate of the ink components to the recording paper is adjusted, and the desired density from low to high can be adjusted. This enables transfer recording between intermediate densities.

[Problem that the invention seeks to solve]

However, in the conventional thermal transfer ink sheet as described above, when the thermal head is heated with low heat generation energy to perform low-density transfer recording, the melt viscosity of the ink component of the heat-melting ink layer 3 is However, since it is difficult to obtain a sufficiently low viscosity to achieve a suitable low density viscosity, significant density unevenness occurs in low-density transfer recordings, and a homogeneous and clear low-density recorded image cannot be obtained.

In view of the above-mentioned conventional drawbacks, the present invention provides the ink components constituting the hot-melt ink layer with a property of lowering the melt viscosity during low-energy heating, thereby increasing the density during low-density transfer recording. It is an object of the present invention to provide a novel thermal transfer ink sheet for halftone recording, which allows a uniform, low-density recorded image to be obtained.

[Means for solving problems]

In order to achieve the above object, the present invention adds a non-drying oil to an ink component consisting of a coloring material and a low melting point wax material in a heat-melting ink layer provided on a sheet base material via an intermediate adhesive layer. The melt viscosity of the ink component is lowered by adding 2 to 60% by weight of the ink component.

[For production]

The thermal transfer ink sheet of the present invention has an ink component consisting of a coloring material and a low-melting wax material constituting a heat-melting ink layer.
Since the non-drying oil is added in an amount of 2 to 60 ffiff1% of the ink component, it is possible to lower the melt viscosity of the ink component by low energy heating.

Therefore, during low-density transfer recording by low-energy heating, a homogeneous low-density recorded image without density unevenness can be obtained. Furthermore, the low viscosity effect of this ink component also produces secondary effects such as improved sensitivity to transfer density.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view of a main part of an embodiment of a thermal transfer ink sheet according to the present invention.

In the figure, 21 is a sheet base material made of polyethylene terephthalate film (PET) with a thickness of, for example, 7 μm, and 22 is a sheet base material 21 on which an adhesive made of polyamide resin or polyester resin is coated to a thickness of 3 μm. This is the intermediate adhesive layer applied.

Further, on the intermediate adhesive layer 22, for example, 0.4% of a dye consisting of Kayaset Black (manufactured by Nippon Kayaku Co., Ltd.) is applied as a coloring agent.
ili part, 1.4 parts by weight of fatty acid amide wax (manufactured by NOF Corporation) and 1.4 parts by weight of paraffin wax (manufactured by 8KO Fine Chemicals Co., Ltd.) as low melting point wax materials, and castor oil, for example, in the above ink components. , or 1.0 parts of heavy metal of a non-drying oil such as rapeseed oil is added and mixed with heat, and a filling material consisting of finely powdered carbon black (manufactured by Nippon Kayaku Co., Ltd.) with excellent cohesion is added to this mixture. A thermal transfer ink sheet has a structure in which a heat-melting ink layer 23 containing 1.6 parts by weight of the heat-melting ink layer 23 mixed and dispersed is coated to a thickness of 10 μm.

However, the transfer characteristics of a thermal transfer ink sheet having such a structure are such that the ink sheet is mounted on a recording paper disposed in a thermal printer with the ink layer surface facing each other, and the thermal head is pressed, and the applied electric power is IOW/n
+m2. As a result of transferring and recording a solid image under printing conditions with a printing pulse width of 4 ms, the transfer density (0,0) was as high as 1.2, as shown by transfer characteristic curve A in Figure 2, and the density was A clear and even transferred recorded image was obtained.

Furthermore, when a solid image was transferred and recorded in the same manner under the printing conditions where the applied power was LOW/mm'' and only the print pulse width was 1.0ms, the transfer density (0,0) was as low as 0.2. A homogeneous transferred recorded image without density unevenness was obtained.

Another characteristic curve B shown in FIG. 2 shows the transfer sensitivity characteristics of a conventional thermal transfer ink sheet in which a similar solid image was transferred and recorded under the above printing conditions in order to compare the transfer characteristics of the thermal transfer ink sheet of the present invention. In the transfer recording of a solid image under printing conditions where the printing pulse width is 2111S or less, density unevenness occurs noticeably in the transferred recorded image, making it difficult to obtain a clear transferred recorded image.

Furthermore, as is clear from the comparison of both characteristic curves A and B, the thermal transfer ink sheet of the present invention to which non-drying oil is added has a higher transfer density of the recorded image than the conventional one by transfer recording with the same heating energy. This lowering of the viscosity of the ink component also has the secondary effect of improving the sensitivity to transfer density.

Further, in the detailed explanation of the present invention, the amount of non-drying oil added is approximately 30 w 1% with respect to the ink component consisting of a coloring material and a low melting point wax material, but There is naturally an appropriate amount of drying oil to be added. For example, if the amount added is 60wt% or more, the melt viscosity of the ink component will decrease more than necessary during thermal transfer recording, and not only the ink component but also the heat melt A problem occurs in that a part of the ink layer is peeled off and transferred to the recording paper side.

Furthermore, if the amount added is less than 2 wt%, there is almost no effect due to the addition, so the amount of non-drying oil added should be 2 to 60-1%.
A range of is appropriate.

〔Effect of the invention〕

As is clear from the above description, according to the thermal transfer ink sheet according to the present invention, by adding an appropriate amount of non-drying oil to the ink components constituting the heat-melting ink layer, the ink components can be heated with low energy. It is possible to lower the melt viscosity of the ink, and it has the excellent advantage of being able to obtain a homogeneous low-density recorded image without density unevenness in low-density transfer recording by low-energy heating. It is extremely advantageous when applied to this type of thermal transfer ink sheet for halftone recording, as it has the secondary effect of improving the sensitivity to transfer density due to the lower viscosity of the components.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part showing an embodiment of a thermal transfer ink sheet according to the present invention, FIG. 2 is a diagram showing transfer and re-recording characteristics of a thermal transfer ink sheet according to the present invention, and FIG. 3 is a conventional thermal transfer ink sheet. FIG. 2 is a cross-sectional view of a main part for explaining the sheet. In FIG. 1, 2I represents a sheet base material, 22 represents an intermediate adhesive layer, and 23 represents a hot-melt ink layer. Shumeime '16t A row ε & Chaos Akizuru prison curry consideration No. 1131 □ lzurusfuku (outside S) Transcript Nuka Tokusha diagram 2nd 1 Conventional Eve base 9uth φi; 4 Ikuo last year 1D90 Figure 3

Claims (2)

[Claims] (1) In an ink sheet in which a heat-melting ink layer (23) consisting of a coloring material, a low melting point wax material, and a filler is provided on a sheet base material (21) via an intermediate adhesive layer (22), the above color A thermal transfer ink sheet characterized by adding a non-drying oil to an ink component consisting of a wax material and a low melting point wax material. (2) The amount of the non-drying oil added is 2 to 60% of the ink component.
Claim No. (1) characterized in that it is % by weight.
Thermal transfer ink sheet described in section.