JPS6224278B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal transfer two-color recording method for transferring two-color recorded images onto a recording medium.

The thermal transfer recording method has the general characteristics of the thermal recording method, such as the equipment used is lightweight, compact, noiseless, and has excellent operability and maintainability. It has the characteristic of having excellent image durability, and has recently begun to be widely used.

This thermal transfer recording method generally uses a thermal transfer material formed by coating a sheet-like support with a thermal transferable ink made of a heat-melting binder and a colorant dispersed therein. The ink layer is superimposed on the recording medium so as to be in contact with the recording medium, and heat is supplied from the support side of the thermal transfer material by a thermal head to transfer the melted ink layer onto the recording medium, thereby creating a heat supply shape on the recording medium. It forms a transfer ink image according to the

Furthermore, there is a strong market demand for two-color printing while taking advantage of the advantages of the thermal transfer recording method, and various techniques for obtaining two-color printing have been proposed.

Conventionally, two images were recorded on plain paper using a thermal transfer recording method.
As a color printing method, JP-A-56-148591 discloses a method in which two heat-melting high melting point ink layers A and a low melting point ink layer B containing different amounts of coloring are sequentially laminated from the substrate side on a substrate. In the case of low heat applied energy, only the low melting point ink layer B is transferred onto the plain paper, and in the case of high heat applied energy, both the heat melting ink layers A and B are transferred to obtain a two-color recording. A thermal transfer recording element is disclosed. In this method, if the melting point difference between layers A and B is small, it is difficult to separate the two layers because the same type of material is used for layers A and B. Therefore, it is difficult to separate the two layers. Therefore, if the melting point difference is increased, the melting point of the B layer must be lowered considerably in order to improve the transferability of the entire ink layer, which will cause a decrease in storage stability and the occurrence of background smearing, thereby improving the print quality. Two-color printing is not possible.

Furthermore, Japanese Patent Application Laid-Open No. 59-64389 discloses a two-color thermal transfer ink sheet in which an ink layer consisting of an ink that melts and leaches by heating and an ink that melts and peels off at a temperature higher than the melting and leaching temperature is provided on a substrate. However, in this method, each ink layer is composed of a different kind of material, and it is thought that color separation is better than the former method, but in principle, a low melting point material must be used, and the It is difficult to avoid stains and decreased shelf life. In addition, a problem common to both is that two-color recording cannot be performed without changing the applied energy. The applied energy had to be controlled for color printing, and the control was complicated.

An object of the present invention is to provide a thermal transfer two-color recording method that can provide clear two-color recording prints on plain paper in a simple manner while eliminating the above-mentioned drawbacks and maintaining various thermal transfer performances. be.

In the recording method of the present invention, each color tone is different and difficult to mix with each other when heat is applied.
The first ink layer and the second ink layer, which have the characteristics that the ink layer is easily separated from the first ink layer and that the first ink layer is easy to separate from the support after a period of time has passed after heat application, are placed on the support and the second ink layer. Using a heat-sensitive transfer material having a first ink layer and a second ink layer, a second ink layer is used.
When recording by bringing the ink layer side into contact with a recording medium and applying thermal energy from the support side, the second ink layer is separated from the first ink layer in accordance with the above-mentioned characteristics, and the separation timing between the recording medium and the support is controlled. The method is characterized in that it is selected based on whether it is easy to separate and when the first ink layer is easy to separate from the support.

That is, as a result of research for the above-mentioned purpose, the inventors of the present invention have developed a thermal transfer having a two-layer structure in which a first heat-melting ink layer of color tone A and a second heat-melting ink layer of color tone B are laminated in order from the support side. The thermal transfer material and the thermal head are opposed to each other and thermal energy is applied to transfer the heat-fusible ink layer to the paper. Immediately thereafter, the thermal transfer material is peeled off, leaving only the second ink layer. is transferred to the recording medium, and on the other hand, after the thermal transfer ink layer is transferred to paper, an ink cooling process of the thermal transfer material is provided to separate the thermal transfer material and the recording medium,
It has been found that the ink layer peels off from the first ink layer and both the first ink layer and the second ink layer are transferred to the recording medium. Therefore, for example, when color tone A is black and color tone B is red, two-color recording of black and red can be obtained.

Hereinafter, the present invention will be described in further detail with reference to the drawings as necessary. In the following description, "%" and "part" expressing quantitative ratios are based on weight unless otherwise specified.

FIG. 1 is a schematic cross-sectional view in the thickness direction showing an example of a thermal transfer material in the most basic embodiment used in the recording method of the present invention. That is, the thermal transfer material 5
Usually, a thermally transferable ink layer 4 is formed on a sheet-like support 1.

Further, the thermal transferable ink layer 4 itself has a multilayer structure, and consists of a first ink layer 2 and a second ink layer 3 provided from the support 1 side.

As the support 1, conventionally known films and papers can be used as they are, such as relatively heat-resistant plastic films such as polyester, polycarbonate, triacetyl cellulose, nylon, and polyimide, cellophane, or parchment paper. , condenser paper, etc. can be suitably used.
The thickness of the support is preferably about 1 to 15 μm when considering a thermal head as a heat source during thermal transfer, but for example, when using a heat source such as a laser beam that can selectively heat the thermal transferable ink layer. There are no particular restrictions.

In addition, when using a thermal head, a heat-resistant protective layer made of silicone resin, fluororesin, polyimide resin, epoxy resin, phenolic resin, melamine resin, nitrocellulose, etc. is provided on the surface of the support that comes into contact with the thermal head. This makes it possible to improve the heat resistance of the support, or to use support materials that could not be used conventionally.

The first ink layer 2 needs to have good separation between the first ink layer 2 and the second ink layer 3 when thermal energy is applied. Moreover, the first ink layer 2
When the time from when thermal energy is applied to when the support 1 is separated from the recording medium is long, that is, when the thermal transfer material 5 and the recording medium are in close contact with each other facing each other, and after heat is applied, they are in close contact with each other. When the thermal head continues to run and the thermal transfer material has cooled considerably, the support 1
It is necessary that the first ink layer 2 is easily peeled off.

For this reason, heat-melting binders include natural waxes such as spermaceti wax, beeswax, lanolin, carnauba wax, candelilla wax, Montan wax, and ceresin wax, and petroleum waxes such as paraffin wax and microcrystalline wax. , synthetic waxes such as oxidized waxes, ester waxes, low molecular weight polyethylene, and fiberglass waxes, higher fatty acids such as lauric acid, myristic acid, palmitic acid, stialic acid, and behenic acid, and higher alcohols such as stearyl alcohol and behenyl alcohol. Contains at least 50% of esters such as sucrose fatty acid ester, sorbitan fatty acid ester, amides such as oleylamide, and other polyolefin resins, polyamide resins, polyester resins, epoxy resins, and polyurethane resins. Resin, polyacrylic resin, polyvinyl chloride resin, cellulose resin, polyvinyl alcohol resin, petroleum resin, phenolic resin, polystyrene resin, vinyl acetate resin, natural rubber, styrene-butadiene rubber, isoprene rubber, chloroprene By appropriately mixing elastomers such as rubber, polyisobutylene, polybutene, or plasticizers, and oils such as mineral oil and vegetable oil, the melting temperature of the ink layer including colorants and other additives is 50°C to 150°C, at 150°C. It is desirable that the melt viscosity (rotational viscometer) is 500 CPS or less.

The melting temperature referred to in the present invention is measured using a Shimadzu flow tester CFT500 with a load of 10 kg and a heating rate of 2°C/
When the apparent viscosity-temperature curve of the sample ink is determined under the conditions of 100 min, it is determined as the outflow starting temperature.

The second ink layer 3 melts and softens when heat is applied from the thermal head and firmly adheres to the recording medium, and it is difficult to mix with the first ink layer 2 when the second ink layer 3 is in a molten state. The heat-melting binder for this purpose contains at least 50% of the above-mentioned resins and the above-mentioned waxes,
Mix appropriate oils such as plasticizer, mineral oil, vegetable oil, etc.
Melting temperature as ink layer is 60℃~150℃, 150℃
Melt viscosity (rotational viscometer) of 200CPS ~
It is better to choose so that it will be 1000000CPS. Also, the second
In order to improve the sharpness of printing on the ink layer 3, the second ink layer 3 may be formed into a dot shape, or the surface of the second ink layer may be formed into an uneven shape.

The thickness of the first ink layer 2 is preferably in the range of 0.5μ to 10μ, and the thickness of the entire thermal transferable ink layer is 2μ to 10μ.
20μ is preferred.

If you want to obtain the same color tone as the first ink layer 2 and the second ink layer 3, it is better to place a dark color such as black in the first ink layer 2 and a bright color such as yellow in the second ink layer 3. , when it is desired to obtain a color mixture of the color tone of the first ink layer 2, the color tone of the second ink layer, and the color tone of the second ink layer 3, for example, the first ink layer 2 is yellow, the second ink layer 2 is yellow, and the second ink layer 3 is yellow.
If the ink layer 3 is colored magenta, magenta and red can be obtained. In addition, by changing the pigment concentration or layer thickness ratio of each layer, various recordings of two different colors can be obtained.

As the colorant, various dye pigments widely used in the field of printing and recording are used. The content of the colorant is 1 to 80% for each of ink layers 2 and 3.
A range of % is appropriate. Moreover, additives such as a dispersant or a filler made of fine metal powder, fine inorganic powder, metal oxide, etc. may be added to each of the ink layers 2 and 3, if necessary.

Regarding the relationship between the first ink layer 2 and the second ink layer 3, it is desirable to select materials that are not compatible with each other, but even if the materials are compatible, they can be separated from each other due to the difference in their melt viscosity. becomes.

To obtain the heat-sensitive transfer material used in the present invention, the heat-melting binder, colorant, and additives described above for each of the ink layers 2 and 3 are melt-kneaded using a dispersion device such as an attritor, or a suitable method is used. A first ink layer and a second ink layer are obtained by kneading the ink with a suitable solvent to obtain a hot-melt, solution or dispersion ink, and sequentially coating these inks on a support and drying as necessary. They should be formed in this order.

The planar shape of the thermal transfer material used in the present invention is as follows:
Although not particularly limited, it is generally used in the form of a typewriter ribbon or a wide tape used in line printers.

Now, the thermal recording method of the present invention using the above thermal transfer material will be explained below. In the following, a case will be explained in which the most typical heat head is used as the heat source.

FIGS. 2 and 3 are schematic cross-sectional views in the thickness direction of a heat-sensitive transfer material showing an outline of the case where only the second ink layer 3 is transferred. FIG. 2 shows the state before recording. In Fig. 2, 5 is a thermal transfer material, 6 is a thermal head,
6b is the heater part of the thermal head, 7 is the recording object, 8
indicates the platen.

Now, a case where the first ink layer 2 is black and the second ink layer 3 is red will be described. FIG. 3 shows the state after recording, in which the thermal head 6 moves to the right, the thermal transfer material 5 is wound up on a reel (not shown), and the thermal transfer material 5
This shows a state in which the red recording material 3a is peeled off from the recording medium 7 immediately after passing through the heater section 6b of the thermal head 6, and a red record 3a is obtained on the recording medium 7.

FIGS. 4 and 5 are schematic cross-sectional views in the thickness direction of a thermal transfer material showing an overview of the case where both the first ink layer 2 and the second ink layer 3 are transferred. FIG. 4 shows the state before recording. The difference from the example shown in Figure 2 is that
After the thermal transfer material 5 is heated, a pressing member 9 is provided for separating the recording medium 7 and the thermal transfer material 5 after the recording medium 7 and the thermal transfer material 5 run idly for a certain distance l while remaining in close contact with each other. be. The member 9 is provided, for example, on a carriage (not shown). The member 9 moves in conjunction with the thermal head 6 while maintaining a certain distance l, and is configured to move back and forth as necessary. That is, when the member 9 is moved back, the thermal transfer material 5 is peeled off from the recording medium 7 immediately after the thermal head 6 has passed, as shown in FIG. On the other hand, when the member 9 protrudes forward, the thermal transfer material 5 and the recording medium 7 remain in close contact with each other even after passing through the thermal head 6, as shown in FIG. The time from application to peeling off of the thermal transfer material 5 becomes longer.

FIG. 5 shows the state after recording, in which the heat-sensitive transfer material 5 is wound up on a reel (not shown) while the head 6 is running to the right after heat is applied to it, and then the member 9
Immediately after, the thermal transfer material 5 and the recording medium 7 are separated,
Transferring both the first ink layer 2 and the second ink layer 3,
This shows that a black recording 2a was obtained on the recording medium 7.

FIGS. 6 and 7 are schematic cross-sectional views in the thickness direction of a heat-sensitive transfer material showing another example. FIG. 6 shows the method for obtaining a red record, which is the same as that shown in FIGS. 2 and 3.

FIG. 7 shows a method for obtaining a black record. The difference between the example shown in FIG. 7 and the examples shown in FIGS. 4 and 5 is that after the thermal transfer material 5 is heated by the thermal head 6 and comes into close contact with the recording medium 7, it remains unchanged for a certain distance l. A member to be peeled off after running idly is detachably provided integrally with the thermal head 6 and has a length l.
The pressing member 10 is used, and in this case, the head is replaced when a red record is obtained and when a black record is obtained, or only the member 10 is attached and detached to obtain a two-color record. Further, the member 10 may be configured to move back and forth like the member 9 shown in FIG. 4.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example Prescription A Terpene-phenol copolymer resin 10 parts Oil-soluble red dye 1 part MEK (methyl ethyl ketone) 89 parts Dissolve the above resin in MEK, dissolve the oil-soluble red dye in the solution, and prepare a coating material for the second ink layer. I gave it an A. Furthermore, what is terpene-phenol copolymer resin?
It is a polycondensate of terpene and bisphenol A whose main components are - and β-pinene.

Prescription B Carbon black 12 parts Oxidized wax 30 parts Low molecular weight polyethylene 10 parts Paraffin wax 48 parts After heating and melting the oxidized wax, low molecular weight polyethylene, and paraffin wax, carbon black was mixed and stirred, and then sand milled while heating. Carbon black was dispersed for 30 minutes to form a coating material B for the first ink layer.

The above coating material B was hot-melt coated onto a 6μ thick polyethylene terephthalate film using a coating bar to obtain a first ink layer with a thickness of 4μ.
Subsequently, coating material A was solvent coated on the above coating film, and then heated and dried in an oven at 80°C for 3 minutes to give a 2μ
A second ink layer was obtained to complete a thermal transfer material.

This was cut into a tape shape with a width of 8 m/m, loaded into a thermal transfer printer used in Canoward 45S, and printed on copy paper at the maximum print volume, resulting in clear red prints. Next, printing was performed by increasing the contact time between the heat-applied thermal transfer material and the copy paper (as shown in FIG. 4 or 7), and a clear black print was obtained on the copy paper.

As explained above, the present invention uses a thermal transfer material with overlapping ink layers that are difficult to mix with each other when heat is applied, and by changing the timing of peeling between the thermal transfer material and the recording medium, the amount of heat applied can be reduced. It is very useful as it allows you to get clear two-color printing without changing anything.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view in the thickness direction of the thermal transfer material used in the present invention, and FIGS. 2 and 3 are schematic cross-sectional views in the thickness direction of the thermal transfer material showing an outline of the case where only the second ink layer is transferred. Cross-sectional view, Figures 4 and 5
The figure is a schematic cross-sectional view in the thickness direction of a thermal transfer material showing an outline of the case where both the first ink layer and the second ink layer are transferred, and FIGS. 6 and 7 are thickness directions of the thermal transfer material showing another example. It is a schematic cross-sectional view of the direction. In the figure, 1... Support, 2... First ink layer, 3... Second ink layer, 4... Thermal transfer ink layer, 5... Thermal transfer material, 6... Thermal head, 6b...
...heater part of thermal head, 7...recorded object, 8...
. . . platen, 9, 10 . . . pressing member.

Claims (1)

[Claims] 1. Each color tone is different and difficult to mix with each other when heat is applied. Immediately after heat is applied, the second ink layer is easy to separate from the first ink layer. Using a thermal transfer material having a first ink layer and a second ink layer in the order of the support, the first ink layer, and the second ink layer, in which the first ink layer has a characteristic that the first ink layer is easily separated from the support, When recording by bringing the layer side into contact with a recording medium and applying thermal energy from the support side, the second ink layer is separated from the first ink layer in accordance with the above-mentioned characteristics, and the separation timing between the recording medium and the support is controlled. A thermal transfer two-color recording method characterized in that the method is selected based on whether the first ink layer is easy to separate from the support or when the first ink layer is easy to separate from the support.