JPS6064896A - Thermal transfer recording ink sheet - Google Patents

Abstract

PURPOSE:To enable to record an excellent halftone of dense and pale tone even when energy applied to a thermal print head is as low energy by using two types of low melting point materials having lower mutual solubility to dye when a low melting point material contained in an ink layer is lower. CONSTITUTION:A halftone adhesive layer 2 is formed on a base material 1, 1pt.wt. of Kayaset black of dye, 1pt.wt. of low melting point material which has low solubility with dye and exhibits 42 deg.C of melting point of cane suger ester, 1.5pt.wt. of low melting point material which has higher solubility with cane sugar ester with dye and exhibits 77 deg.C of melting point such as fatty acid amide, and 1pt.wt. of carbon black such as filler are coated thereon. When the energy of the thermal print head is reduced, the cane suger ester having low melting point is first melted, and the melted ink is transferred onto the recording sheet, by solubility to the Kayaset of dye is low, halftone print with low density is transferred.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to an ink sheet for thermal transfer recording, and particularly to an ink sheet for thermal transfer recording suitable for halftone recording.

Background of the technology Capacitors are placed on a base material such as paper, through an intermediate adhesive layer such as polyamide resin, and filled with voids of a filler consisting of fine powders such as organic pigments, inorganic pigments, and metal powders at room temperature. Then, an ink layer made of a solid dye, a low melting point material, etc. is provided to form an ink sheet for thermal transfer recording, and a thermal print head that is partially heated by printing information is pressed from the base material side of the ink sheet for thermal transfer recording. A thermal transfer recording method in which the ink in the ink layer is partially melted and the melted ink is transferred onto recording paper is well known.

This thermal transfer recording method makes no noise during printing, can be printed on plain paper, does not cause chemical changes that occur when printing on thermal paper, and has excellent recording preservation characteristics. It has many characteristics such as:

(C1 Prior art and problems) Recently, even in such thermal transfer recording methods, instead of the conventional binary printing of black "1" and white (background) "0",
It has become desirable to record intermediate tones between black "1" and white (background) "0". Conventionally, as a method to obtain halftone recording, by changing the value of the applied energy applied to the thermal print head, the ink layer, which is in a solid phase at room temperature surrounded by fine powder such as the filler of an ink sheet for thermal transfer recording, is Halftone recording was obtained by controlling the amount of melting and seeping onto the recording paper.

However, when the energy applied to the thermal print head is set to low energy, problems such as transfer unevenness occur in the transferred image transferred onto the recording paper.

(dl Purpose of the Invention The present invention eliminates the above-mentioned problems, and even when the energy applied to the thermal print head is set to low energy,
The object of the present invention is to provide a new ink sheet for thermal transfer recording that is capable of recording halftones with excellent gradation.

tel Structure of the Invention To achieve the above object, the ink sheet for thermal transfer recording of the present invention is an ink sheet for thermal transfer recording comprising an ink layer comprising a dye, a low melting point material, and a filler on a base material. The ink layer includes at least two types of low melting point materials having different melting points, and the lower the melting point of the low melting point material, the lower the compatibility with the dye.

ff) Embodiment of the Invention The figure is a cross-sectional view of an ink sheet for thermal transfer recording according to the present invention. As shown in the figure, a poly layer 3 with a thickness of 2 μm is formed on a base material 1 made of capacitor paper with a thickness of 10 μm. It is formed by coating.

To form such an ink sheet for thermal transfer recording, a solution of polyester resin dissolved in a solvent of toluene is applied to a thickness of 2 μm on a base material 1 made of capacitor paper with a thickness of 10 μm using a bar coater coating device, and an intermediate adhesive is formed. layer 2
form. On this intermediate adhesive layer 2, 1 part by weight of a low melting point material such as sucrose ester (manufactured by NOF Corporation), which has a low melting point of 42°C and has low compatibility with dyes described below, and 1 part by weight of a fatty acid Melting point is 77℃ like amide (manufactured by NOF Corporation)
1.5 parts by weight of the low-melting point material, which shows a high value and has higher compatibility with the dye described below than sucrose ester, 1 part by weight of the dye Kayascent Blank (manufactured by Nippon Kayaku Co., Ltd.), and the filler. A solution in which 1 part by weight of carbon blank (manufactured by Nippon Kayaku Co., Ltd.) was melted and mixed in an acetone solvent and sufficiently dispersed was coated with a bar coater coating device to a thickness of 10 μm, and then
It was dried in a dryer to form an ink sheet for thermal transfer recording of the present invention.

The ink sheet for thermal transfer recording of the present invention is placed on top of the recording paper and then installed in a thermal facsimile apparatus. When the electric power applied to the thermal print head of this thermal facsimile device was set to 10 W/fi2, and the pulse width of this applied power was set to 4 m5ec, a rectangular solid black image was transferred onto the recording paper. A homogeneous solid transfer image with (0,D) of 1.2 was obtained.

In addition, in order to obtain halftone recording, the applied power to the thermal print head of the thermal facsimile device was 10W/l.
I+12, and the applied pulse width of this applied power is 1m5e
As for c, when solid transfer was performed with the applied energy applied to the thermal print head reduced, the result was 0.
A record of homogeneous medium and spacing was obtained with a decrease in 0 to 0.5.

This means that when the thermal print head is pressed against the recording paper in a state where the energy applied to the thermal print head is low in order to obtain halftone recording on the base material 1 side, the low energy contained in the ink layer 3 Among the melting point materials, sucrose ester, which has a low melting point and low compatibility with dyes, is first melted, and the melted ink is transferred onto the recording paper. Since this sucrose ester has low compatibility with the dye colorant blank, a low-density halftone print is transferred to the recording paper.

In order to compare with the ink sheet for thermal transfer recording of the present invention, a sheet for thermal transfer recording was prepared using the same materials, except for the sucrose ester, among the materials constituting the ink layer of this example. An ink sheet was formed, a recording paper was placed on this thermal transfer recording ink sheet, and the same solid transfer was performed by installing it in the thermal facsimile device described above.
When the energy applied by the thermal print head was set to low energy, uneven transfer easily occurred in the transferred image transferred onto the recording paper, and only prints with extremely poor homogeneity were obtained.

In addition, an ink sheet for thermal transfer recording was formed using the same materials for forming the ink layer of this example, except for the fatty acid amide, which is a low melting point material, and the ink sheet for thermal transfer recording was used in the same manner. When we conducted a series of tests, we found that even when the energy applied to the thermal print head was set to high energy, it was not possible to record with a high recording density of 1 or more, so even if the energy applied to the thermal print head was changed, , the recording density of the transferred image transferred to the recording paper did not vary over a wide range, and therefore good halftone recording was not possible.

On the other hand, if the ink sheet for thermal transfer recording of the present invention is used, when the energy applied to the thermal print head is changed from a high energy state to a low energy state in order to obtain halftone recording, The recorded density of the transferred image transferred to the recording paper varied with good reproducibility from high density to low density, and moreover, records with high print quality were obtained.

In addition to this example, in order to further increase the transfer sensitivity during halftone recording, when forming the ink layer, fatty acid amide, which is a low melting point material with a higher melting point, is added to the side closer to the base material. A mixed solution of the dye Kayasent black, the filler carbon blank, and acetone is applied, and then on top of that, the lower melting point material sucrose ester, the dye Kayasent black, the carbon blank, and acetone are applied. A thermal transfer recording ink sheet having a two-layer structure may be formed by coating a mixed solution of the above.

[gl Effects of the Invention As described above, according to the ink sheet for thermal transfer recording of the present invention, when the energy applied to the thermal printing gutter is changed from a high energy value to a low energy value, the transferred print recording is improved. The effect is that a uniform halftone record is obtained in which the density varies almost linearly from a high density to a low density.

[Brief explanation of drawings]

The figure is a sectional view showing an embodiment of the ink sheet for thermal transfer recording of the present invention. In the figure, 1 is a base material, 2 is an intermediate adhesive layer, and 3 is an ink layer.

Claims (1)

[Claims] In a structure in which an ink layer consisting of a dye, a low melting point material, and a filler is provided on a base material, the ink layer includes at least two types of low melting point materials having different melting points, and the low melting point material having a low melting point is An ink sheet for thermal transfer recording that is characterized by low compatibility with dyes.