JPS6283186A - Thermal transfer material - Google Patents

Abstract

PURPOSE:To obtain a thermal transfer material imparting a transfer recording image having good printing quality even to a recording medium inferior in surface smoothness, by providing recessed parts with a predetermined diameter dimension to one surface of a support in a scattered state and forming a liquid ink layer and a thermoplastic resin layer in this order. CONSTITUTION:The diameter l of each of the recessed parts 2a formed to one surface of a support 2' in a scattered state is pref. 5-100mum and the depth (h) is pref. about 0.1-15mum. The cross-sectional shape or flat surface shape of each recessed part 2a is set regularly while the securing of the uniformity of recording density becomes much easier. A liquid ink layer 3 is stably held in each recessed part 2a in a membrane form by surface tension between a thermoplastic resin layer 4 and the support 2 to constitute a thermal transfer material. In the thermal transfer material to which heat is applied, the liquid ink 3 flows out through the hole formed by thermally softening or melting the thermoplastic resin layer to be transferred to a recording medium to form a transfer recording image.

Description

Detailed Description of the Invention By Katsuhiko ■ The present invention can be applied to, for example, recording media with poor surface smoothness by forming a layer of liquid ink on a support having recesses on its surface. 4 transfer recorded images with good print quality
Regarding thermal transfer materials.

The ff1J nine-week thermal transfer recording method is capable of recording on plain paper, and the apparatus used is lightweight, compact, and noiseless, and has recently been widely used.

This thermal transfer recording method generally uses a sheet-like support [
- a heat-sensitive transfer material coated with a heat-melt ink comprising a 7i coloring agent dispersed in a heat-melt binder; By superimposing the ink on the recording medium and supplying heat from the support side of the thermal transfer material with an external heat generating member such as a thermal head, the molten ink is transferred onto the recording medium according to the shape of the heat supply. It forms an image.

However, in the conventional thermal transfer recording method, (
When printing on a recording medium with low Z lubricity, the ink that melts during transfer cannot penetrate the width of the M&fibres of the paper that is the recording medium, and only adheres to the convex parts of the surface and the vicinity thereof, resulting in poor transfer. The disadvantage is that the edges of the printed image may not be sharp or parts of the image may be missing, resulting in poor print quality.

In order to improve this printing quality, it is possible to use a heat-melt binder with a low melting point, but in this case, the heat-melt ink layer becomes sticky even at relatively low temperatures, so This causes inconveniences such as a decrease in the storage stability of the thermal transfer material and staining of non-printing areas of the recording medium.

The main purpose of the present invention is to eliminate the drawbacks of the conventional thermal transfer recording methods mentioned above, maintain various thermal transfer performances, and provide a recording medium with good surface smoothness. Another object of the present invention is to provide a heat-sensitive transfer material that can provide a high-quality transferred recorded image even to a recording medium with poor surface smoothness.

According to the research of the present inventors, a liquid ink layer and a thermoplastic resin layer are formed on a support having scattered dot-like recesses on the negative side to form a thermal transfer material. was found to be extremely effective in achieving the above objectives.

The thermal transfer material of the present invention is based on such knowledge, and more specifically, the diameter of the dots on the negative side is 5 to 1100 mm.
On the concave forming surface of the support body provided with the concave portion of JL,
It is characterized by forming a liquid ink layer and a thermoplastic resin layer in this order.

In the thermal transfer material of the present invention, the liquid ink layer of the support-L exists substantially in the dotted recesses formed on the surface of the support, and a thermoplastic resin layer is provided on the ink layer. Because of this, the liquid ink is stably held between the support and the thermoplastic resin layer.

In particular, even when pressure is applied from a thermal head or the like during thermal transfer, the thickness of the liquid ink layer, which is supported by the convex portions of the support and substantially exists in the dotted concave portions, hardly changes.

The liquid ink layer formed on the support is microscopically non-uniform in thickness, but during actual thermal transfer recording, the liquid ink layer has a substantially (macroscopically) uniform thickness. By utilizing the liquid ink itself's good permeability into the surface of the recording medium, it is possible to transfer a recorded image to the recording medium with a uniform density and faithful to the pattern of heat application. can be formed on top.

Therefore, by performing thermal transfer recording using the thermal transfer material of the present invention, the above-mentioned effects are combined with the ink transfer prevention effect in the non-heat-applied area by the thermoplastic resin layer, resulting in excellent selectivity and reproducibility. It becomes possible to improve the transfer recording performance while maintaining the same, and it is possible to obtain a high-quality transfer recorded image without variations in print density or stains in non-printed areas even on recording media with low surface smoothness.

Hereinafter, the present invention will be described in further detail with reference to the drawings as necessary. In the following descriptions, "%" is used to express quantitative ratio.
” and “parts” are based on weight unless otherwise specified.

1. FIG. 1 is a schematic sectional view in the thickness direction of a heat-sensitive transfer material in a basic embodiment of the present invention.

That is, the thermal transfer material 1 of the present invention is formed by forming a layer of liquid ink 3 and a thermoplastic resin layer 4 on a support 2 having scattered recesses 2a on one surface.

As the support 2, conventionally known films and papers can be used as they are.1 For example, films of relatively heat-resistant plastics such as polyester, polycarbonate, triacetylcellulose, polyamide, polyimide, cellophane 16, or sulfuric acid. Paper or the like can be suitably used.

When considering a thermal head as a heat source during thermal transfer, the thickness of the support is usually 2 to 20 #L at the thickest part.
If the whole support is formed into an endless belt shape and used repeatedly, it is preferably about 5 to 50 gm. When used, there are no particular restrictions on the thickness, and by providing a heat-resistant protective layer made of silicone resin, fluororesin, etc. on the surface of the support that comes into contact with a thermal head, etc., the heat resistance of the support can be improved.
Alternatively, using a support material with relatively low heat resistance also provides nf capability.

With reference to FIG. 2(a), which is a schematic cross-sectional view in the thickness direction of the support 2 in the thermal transfer material of FIG. , 5-1100p
The amount is preferably about 20 to 50 g or m. l
It is difficult to form a concave portion 2a in which the surface tension is less than 5 JLm, and it is also difficult to store the liquid ink 3 in the concave portion due to the effect of surface tension. On the other hand, if l exceeds 100 μm, 1, for example, the diameter of the dots constituting the thermal head (usually 120 μm
(about m), the fidelity to the heat application pattern becomes insufficient.

Although the depth h of the recess 2a is related to the strength of the support, it is usually preferably about 0.1 to 15 gm, more preferably about 0.5 to 10 pm.

With reference to FIG. 2(b), which is a schematic plan view of the thermal transfer material shown in FIG.
The distribution rate of the recesses 2a on the support 2° is 10 to 90%.
The above distribution rate here refers to the planar area ratio of the recesses 2a to the surface on which the recesses 2a of the support 2 are formed.
If this distribution ratio is less than 103, the fidelity of the transferred recorded image to the heat application pattern will be insufficient, while if the distribution ratio exceeds 90%, the thickness of the liquid ink layer will be maintained by the convex portions 2b of the support. The effect will no longer be sufficient.

Since the recessed portion 2a described in I- has a groove that stably holds the liquid ink 3 therein, its cross-sectional shape is not particularly limited, and may be, for example, as shown in FIG. 3(a). The planar shape of the recess 2a is not particularly limited, and may be a semicircular or other polygonal shape, for example, a circular shape as shown in FIG. 3(b), or another polygonal shape.

A concave like this? The cross-sectional shape or cross-sectional shape of 52a may be irregular, but if it is regular, it is easier to ensure the fidelity of the transferred recorded image to the heat application pattern or the uniformity of the recorded density. Therefore, it is preferable.

Further, the distribution state of the recesses 2a on the support body 2 may be irregular, but it is more preferable to be regular. In the case of regular distribution, the distribution state is lattice-like or staggered. It doesn't matter.

The liquid ink 3 held in the recesses 2a on the support 2 as described above is obtained by mixing a coloring agent such as a dye or pigment with a liquid substance such as water, animal or vegetable oil, mineral oil, ester compound, or ether compound. A liquid solution at room temperature is used, which has been dissolved or dispersed and the viscosity has been adjusted by adding a resin as necessary. Specifically, for example, writing ink, typewriter ribbon ink, printing ink, etc. are suitably used.

The thermoplastic resin layer 4 formed on the layer of the liquid ink 3 is preferably made of polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, soft polyvinyl chloride, polyvinyl alcohol, polystyrene, polyurethane, etc. with a softening point of 60. ~180°C, more preferably 90°C
The resin layer 4 is made of thermoplastic resin at -120°C, but it is preferable to make the thickness of this resin layer 4 as thin as possible, from 0.1 to 1 l.
OpLm, particularly in the range of 0.5 to 2 lm, is preferably used. Further, the plastic resin layer 4 may be colored with a dye, a pigment, or the like.

In order to obtain the thermal transfer material 1 of the present invention, a liquid ink 3 is applied onto a support 2 having scattered dotted recesses 2a on one surface thereof using an Everor coater, a blade coater, a percoater, etc. After removing the ink adhering to the convex portions 2b on the support 2 using a blade or the like as necessary, a heat r+l plastic resin layer 4 is formed on the applied ink layer so that the uniform thickness is usually 0. .1-10 gm, preferably 0.5-5
It is sufficient to use a thermal transfer material having a layer of liquid ink 3 of gm.
It is the value obtained by dividing the total J, l of the liquid ink 3 existing directly under the surface portion by the area of the surface portion.

The method of forming the concave portion 2a on the support 2 is not particularly limited, and for example, a method of manufacturing by casting using a mold having an uneven shape, or an embossing process using a support having a uniform J-shape. to form a recess 2a,
Alternatively, attach additional resin etc. to the surface of the support to form the convex portion 2.
A method of forming b is used.

It is formed on a layer of liquid ink 3. The thermoplastic resin layer 4 is 1, for example, fA-4, which has the same thickness as this resin layer 4.
It is obtained by laminating a tf plastic resin film on the ink layer. Other 1 For example, the resin layer 4 may be formed by spraying a solution of the above-mentioned thermoplastic resin dissolved in a solvent incompatible with the liquid ink 3 onto the ink layer.

The liquid ink layer 3 is held between the thermoplastic resin layer 4 and the support 2, substantially in the recess 2a, and is stably held in a thin film form due to interfacial tension. constitute the material.

In addition, in the thermal transfer material 1 of the present invention, the liquid ink 3
is maintained between the support 2 and the resin layer 4 in a state that satisfies fidelity to the heat application pattern and pressure resistance against pressure from a thermal head, etc., and as long as this condition is satisfied, for example, in the recess 2a. layer of liquid ink 3 and resin layer 4
There may be a slight gap between the protrusions 2b and 2b.
A liquid ink having a certain thickness may be sandwiched between the resin layer 4 and the resin layer 4.

The thermal transfer recording method using the thermal transfer material 1 described above is not particularly different from a normal thermal transfer recording method, but for the sake of caution, the case where a thermal head, which is a typical heat source, is used will be described.

That is, a recording medium is placed opposite the thermoplastic resin layer 4 of the thermal transfer material 1, and a thermal pulse according to a desired pattern is applied from the support 2 side of the thermal transfer material 1 using a thermal head.

As other heat sources, laser light is also suitably used as described above.

In the heat-sensitive transfer material to which heat is applied, heat is transmitted to the ink 3 layer and the thermo-OT plastic resin layer 4 via the support 2, so that the thermoplastic resin layer 4 is thermally softened or melted, and transferred to the opposing recording medium. The liquid ink 3 is transferred together with the liquid ink 3 or flows out to the recording medium by the applied pressure from the thermal head through holes formed by the thermoplastic resin layer 4 being thermally softened or melted according to the heat application pattern. A transferred recorded image is formed by the transfer.

As is clear from the above, according to the present invention,
A heat-sensitive transfer material is provided, in which a liquid ink layer and a thermoplastic resin layer are formed on a support having scattered concave portions having a diameter of 5 to 100 gm on the − surface.

In the heat-sensitive transfer material obtained in this way, the shape of the ink layer is stably maintained, and the thermoplastic resin layer prevents ink transfer in the non-heat-applied area, so that the liquid ink has good transfer to the recording medium. Penetration can be utilized selectively and with excellent uniformity and reproducibility.

Therefore, by performing thermal transfer recording using the thermal transfer material of the present invention, it is possible to infiltrate liquid ink into the recesses on the surface of the recording medium faithfully to the heat application pattern. Even when printing, a high-quality transferred recorded image can be obtained without variations in print density or stains in non-print areas.

The present invention will be explained in more detail below using Examples and Comparative Examples.

Migokan carbon black 20 parts, cottonseed oil 50 parts, lecithin 10 parts
A liquid ink 3 was obtained by kneading the mixture using a triple roll. This is applied onto the concave formation surface of the support 2, and further softened at a softening temperature of 1
Oxidized polyethylene emulsion (4#1 fat content 3
0%) on the liquid ink layer and the convex formation surface of the support and dried to form a thermoplastic resin layer 4 with a thickness of 0.1 to 1 m to obtain a thermal transfer material 1. Ta.

Next day 1 10 parts of carbon black, 60 parts of paraffin wax (softening point 60 to 65°C), 25 parts of carnauba wax, and 15 parts of ethylene-vinyl acetate copolymer (ethylene/vinyl acetate = 907 to) using an attritor. Te90
The heat-sensitive transfer ink obtained by melt-kneading at .degree. C. was applied onto a polyester film having a thickness of 6 mm using a hot melt coater to form a heat-sensitive transfer ink layer having a thickness of 9 mm to obtain a heat-sensitive transfer material.

The thermal transfer ink layers of the thermal transfer materials of Examples and Comparative Examples obtained as described above were placed facing recording paper, and the printing pressure was set to 0.
2Kg/cm2. Thermal transfer recording was performed with an applied pulse width of 5 msec. The recording paper has a smoothness of 10 sec, 25 sec, and 120 sec using an Oken type smoothness tester.
Three types of paper were used.

The evaluation results of the print quality of the obtained records are shown below.

As is clear from the results of 0: good, Δ: slightly poor, X: poor, the thermal transfer material of the present invention has
This is a thermal transfer material that can provide records of extremely good print quality even if the smoothness of the recording paper is reduced, and does not select only one paper quality.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view in the thickness direction of a basic example of the thermal transfer material of the present invention, and FIG. 2(a) is a schematic cross-sectional view in the thickness direction of the support in the thermal transfer material of FIG. Figure, Figure 2(b)
is a schematic plan view of the above-mentioned support body as seen from the recess formation surface side;
Figure 3(a) is a schematic cross-sectional view in the thickness direction of the support when the surface recesses are formed into a spherical shape, and Figure 3(b) is a schematic plan view of the support as seen from the side where the recesses are formed. . l...Thermal transfer material. 2...Support, 2a...Surface recesses of support, 2b...Surface protrusions of support, 3...Liquid ink. 4...Thermoplastic resin layer. υJ: Figure 1

Claims (1)

[Claims] A layer of liquid ink and a layer of thermoplastic resin are formed in this order on the concave-forming surface of a support having concave portions having a dotted diameter of 5 to 100 μm on one surface. Thermal transfer material.