JPS63191684A - Production of electrotehrmal-type transfer material - Google Patents

Abstract

PURPOSE:To reduce contact resistance at a part of contact with an energizing electrode and suppress diffusion of an electric current through a low resistance layer, by providing the low-resistance layer on a high-resistance layer on the side for contact with the energizing electrode by spray coating. CONSTITUTION:A low-resistance layer is provided by using a coating material comprising a resin and a conductivity-affording agent. By removing a solvent by drying after spray coating, the low-resistance layer is constituted of a conductive resin material comprising a mixture of the resin and the conductivity- affording agent. The resin is preferably an acrylic resin or the like. The conductivity-affording agent may be, for example, a carbon material such as carbon black and graphite, or a powder of a metal such as silver, copper, nickel, aluminum and gold. The resin and the conductivity-affording agent are used in respective relative amounts of 10-60 pts.wt. and 40-90 pts.wt. A mixture of the resin and the conductivity-affording agent is used in the form of the coating material, by diluting with a solvent before spray coating. By the spray coating, the low-resistance layer is provided in the thickness of 0.1-3 mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing an electrically conductive thermal transfer member having a two-layered resistance layer.

[Conventional technology]

The current-carrying thermal transfer recording method is a method in which a current-carrying electrode with a needle-shaped tip called a recording electrode needle is brought into contact with the resistance layer of a transfer body that includes a resistance layer, a conductive layer, and a heat-melting ink layer, and a voltage is applied. The current flows from the current-carrying electrode to the resistive layer and then to the conductive layer before returning to the return electrode.The heat generated when the current passes through the resistive layer partially melts the ink, and the melted portion This is a recording method in which ink is transferred to a recording medium such as yam or other recording medium.

In this current-carrying thermal transfer recording method, when the resistance value of the resistance layer is large, the contact resistance between the current-carrying electrode and the resistance layer also becomes large, resulting in energy loss at that part, and the contact resistance value varies at each part of the resistance layer. There was a problem in that the printing characteristics were deteriorated because the printing characteristics were not uniform and varied widely, which affected the printing characteristics.

Therefore, as a solution to this problem, Japanese Patent Application Laid-Open No. 59-227492
JP-A-60-64893 and the like propose that a resistance layer having a low resistance is provided on the side of the resistance layer that comes into contact with the current-carrying electrode to eliminate contact resistance.

However, the above-mentioned JP-A-59-227492 and JP-A-60-64893 do not disclose specific means for forming the low-resistance layer.
In JP-A No. 9-227492 and JP-A-60-64893, the low-resistance layer (indicated by the expression "current-carrying layer") is also formed to have a thickness of 15 μm. however,
The inventors have investigated that when the low-resistance layer is as thick as 15 μm, even if the contact resistance with the current-carrying electrode can be reduced, the low-resistance layer is too thick. There have been problems in that current diffusion occurs, making it impossible to obtain sufficient printing characteristics, and also causing premature wear of the current-carrying electrodes.

In other words, a thicker low-resistance layer means that the lower-resistance layer is thicker, so the current from the current-carrying electrode is diffused in the low-resistance layer, and less heat is generated in the desired area. , the ink is not melted in the intended area, making it impossible to obtain the desired print. Therefore, it is necessary to increase the applied voltage, and as a result, consumption of the current-carrying t& can be reduced.

In this way, despite the disadvantage that a thick low-resistance layer causes the current to spread, the above-mentioned Japanese Patent Application Laid-Open No. 59-2274
In Publication No. 92 and Japanese Unexamined Patent Publication No. 60-64893,
The reason why the low resistance layer is formed thick is because of its formation method.
This is thought to be due to the fact that it is difficult to form thin.

That is, the above-mentioned Japanese Patent Laid-Open No. 59-227492 and Japanese Patent Laid-Open No. 60-64893 do not disclose a specific means for forming a low resistance layer, and therefore, it is difficult to form a low resistance layer. For this purpose, it is thought that the coating method that has been commonly used in this type of field will be adopted, but the solid content concentration of the coating composition (approximately 3
5.5% by weight), it seems likely that gravure coating or solution casting will be employed.

However, with the most common type of gravure coating, the pressure applied by the gravure roll when forming the low resistance layer may mechanically destroy the high resistance layer that has already been formed. In this case, the destruction of the high-resistance layer and the like becomes significant, making it difficult to form a thin low-resistance layer. Also, to prevent damage to the high-resistance layer, it is possible to form the low-resistance layer before the high-resistance layer, but it is not possible to form the low-resistance layer first and then form the high-resistance layer. However, in the solution casting method, the coating material is poured into a predetermined slit gap to form a coating film, which makes it even more difficult to perform because the low resistance layer is thin and the damage is greater. Variations in the thickness of the layers (in this case, the high-resistance layer, conductive layer, and hot-melt ink layer) also affect layer formation, and in order to reduce the viscosity of the coating material when forming a thin film, the viscosity of the coating material is reduced before drying. It is inherently difficult to form a uniform thin film because the solvent has an adverse effect on the already formed layer, and therefore the thickness mentioned above results in current spreading and poor printing characteristics. This can cause problems and reduce the wear and tear of the electrodes.

[Problem that the invention seeks to solve]

This invention solves the problem of the high contact resistance between the current-carrying electrode and the resistance layer that conventional current-carrying type thermal transfer materials had, which deteriorates printing characteristics, or the formation of a thick low-resistance layer to solve this problem. To solve this problem, we developed a method to form a thin low-resistance layer. The purpose is to reduce the contact resistance with the current-carrying electrode and to reduce the diffusion of current through the low-resistance layer.

[Means for solving problems]

The present invention involves forming a low-resistance layer with a thickness of 0.1 to 3 μm by spray coating on the side of the high-resistance layer having high electrical resistance that generates heat to melt the ink and comes into contact with the current-carrying electrode. In this way, it is possible to lower the contact resistance with the current-carrying electrode, eliminate the negative effects such as current diffusion caused by forming a thick low-resistance layer, and obtain a current-carrying thermal transfer material with good printing characteristics. This is what I did.

That is, in the present invention, since the low-resistance layer is formed by spray coating, the low-resistance layer can be formed with a thickness as thin as 0.1 to 3 μm, and current diffusion due to the low-resistance layer can be prevented. In addition, since the low resistance layer can be formed without any contact with the transfer body or its constituent members with a coating jig such as a gravure roll, the ink layer or conductive layer will not be damaged. By forming such a thin, low-resistance layer, the contact resistance with the current-carrying electrode can be reduced, making it possible to obtain a current-carrying thermal transfer member with good printing characteristics.

In the present invention, a coating material containing a resin and a conductivity-imparting agent is used to form the low-resistance layer, and when the solvent dries after spray coating, the low-resistance layer is formed of a mixture of the resin and the conductivity-imparting agent. It will be composed of a conductive resin material, such as polycarbonate, polyamide, polyimide, polyamideimide, polyurethane,
Polypropylene, polyethylene terephthalate, polybutylene terephthalate, acrylic resin, etc. are preferably used. These resins have a film-forming ability and a binding effect to bind the conductivity imparting agent, and have a melting point or softening point of 150
°C or higher, and the heat is high enough to melt the heat-melt ink during printing (normally, heat-melt ink is about 50 to 14
It is preferably used because it does not melt at temperatures of about 0°C.

On the other hand, as the conductivity imparting agent, for example, carbon-based materials such as carbon black and graphite, and metal powders such as silver, copper, nickel, aluminum, and gold are used. The ratio of these resins and the conductivity imparting agent is 10% of the resin.
It is preferable to use 40 to 911 parts of the conductivity imparting agent to 60 parts by weight. This is because if the resin amount is less than the above range, it will be difficult to form a uniform low resistance layer. On the other hand, if the resin amount is less than the above range, This is because if the number of layers increases, the resistance increases and the low-resistance layer cannot sufficiently fulfill its role of reducing contact resistance.

The resin and the conductivity imparting agent may be mixed in the presence of a solvent because it is necessary to dilute it with a solvent and use it as a coating material before spray painting.
For example, a small amount of a surfactant or the like may be added to the mixture of the resin and the conductivity imparting agent for the purpose of improving the dispersion of the conductivity imparting agent.

In the present invention, a low resistance layer of 0.1
It is formed to a thickness of ~3 μm, but this is because if the thickness of the low resistance layer becomes thicker than 3 μm, current diffusion occurs in the low resistance layer and energy loss occurs as described above. This is because if it becomes thinner than .1 μm, it becomes impossible to lower the contact resistance, which is the role of a low resistance layer, as the thickness decreases, and the variation in contact resistance increases. In other words, the thicker the low-resistance layer, the more likely current diffusion will occur, and the thinner the low-resistance layer, the greater the variation in contact resistance.

For spray painting, a coating material containing a resin and a conductivity imparting agent is used, but in order to easily carry out this spray coating and to control the thickness of the coated object, an important condition is the viscosity of the coating material. And, the moving speed of the object to be coated, that is, the transfer body, must be appropriate. The viscosity of the coating material is preferably about 2 to 50 centimeters,
The solid content concentration at this time corresponds to approximately 1 to IO weight %. Therefore, the above-mentioned JP-A-59-227492
When the solid content concentration is about 35.5% by weight as in Japanese Patent Publication No. 60-64893, the viscosity is too high;
It is clear that a low resistance layer is not formed by spray painting. And the movement speed is usually 5
It is preferable to set it to ~50m/win. By employing such conditions, a low resistance layer can be easily formed with a thickness as thin as 0.1 to 3 μm. In other words, unlike gravure coating, spray painting does not damage high-resistance layers, conductive layers, heat-melt ink layers, etc., and even if there are variations in the thickness of high-resistance layers that have already been formed, As the resistance layer, a thin layer with a uniform thickness can be formed by appropriately setting the viscosity of the coating material and the moving speed of the object to be coated.

In the present invention, the low resistance layer is thinly formed by spray painting as described above, but other parts, such as the high resistance layer, can be formed in the same manner as conventional resistance layers, and the conductive layer and the The ink layer and the like can be formed in a conventional manner.

〔Example〕

Example 1 15 parts by weight of polycarbonate was dissolved in 130 parts by weight of dichloromethane, and conductive carbon black (Pulcan XC-72 (trade name) manufactured by Cabot, Inc., USA) was added to this solution.
) 5.4 parts by weight were added and mixed in a ball mill for 8 hours to disperse. This dispersion was applied onto a 75 μm thick polyester film (polyethylene terephthalate film) by a solution casting method to a dry thickness of 15±1 μm, and dried to form a high resistance layer. When the surface resistance of this high resistance layer was measured, it was approximately 650Ω/hole.

Next, a conductive layer is formed by vapor-depositing aluminum to a thickness of 1,500 mm on this high-resistance layer, and then on the conductive layer, carbon black is used as a coloring agent, and hot-melt ink with wax as the main binder is applied. was applied to a thickness of 4 μm using a hot-melt coating method to form a heat-melt ink layer, and then the polyester film was peeled off from the high-resistance layer.

Next, 50 parts by weight of conductive carbon black was added and mixed into a solution of 50 parts by weight of polycarbonate dissolved in 670 parts by weight of dichloromethane on the side of the high-resistance layer that was in contact with the polyester film, and then 700 parts by weight of dichloromethane was added. The solution viscosity was adjusted to 20 centivoise by adding 50% of the solution (solid content concentration about 7% by weight) to a nozzle diameter of 1%.
The object to be coated, that is, the high-resistance layer side, is moved at a speed of 10 m/+win using a spray coating device with a 00 μm nozzle, and the coating is spray-coated to a dry thickness of 1 μm. After drying, the low-resistance layer is formed. Formed. The surface resistance of this low resistance layer was 100Ω/hole.

The electrically conductive heat-sensitive transfer material produced as described above is shown in FIG. This is a sexual ink layer.

The above-mentioned electrically conductive thermal transfer body was cut into a ribbon shape with a width of 7 fl,
Printing was carried out using bond paper as a recording medium in the manner shown in FIG.

In FIG. 2, 4 is a recording medium made of bond paper;
It is arranged on the heat-melting ink layer 3 side of the electrically conductive heat-sensitive transfer body 10. 5 is a current-carrying electrode made of a tungsten electrode with a diameter of 75 μm; 6 is a return electrode made of tungsten; the current-carrying electrode 5 is brought into contact with the low resistance layer la of the transfer body 10; I am in contact with it. In this state, a voltage of 20 V and 30 mA was applied between the electrodes 5.6 for 0.5 milliseconds to cause the resistance layer 1 (mainly the high resistance layer 1b) to generate heat to perform printing. This printing was performed on five transfer bodies manufactured in the same manner as above, and the size of the printing was measured.

The results are shown in Table 1 as average values and variations.

Example 2 An electrically conductive thermal transfer body was manufactured in the same manner as in Example 1 except that the moving speed of the object to be coated was changed to 20 m/+win and the thickness of the low resistance layer was formed to 0.5 μm, and then Example Printing was carried out under the same conditions as in Example 1. The results are shown in Table 1.

Example 3 An electrically conductive thermal transfer body was manufactured in the same manner as in Example 1, except that the moving speed of the object to be coated was changed to 5 m/win and the thickness of the low resistance layer was formed to 3 μm. Printing was performed under the same conditions. The results are shown in Table 1.

Example 4 An electrically conductive thermal transfer member was manufactured in the same manner as in Example 1 except that the moving speed of the object to be coated was changed to 50 m/min and the thickness of the low resistance layer was formed to 0.1 pm. Printing was carried out under the same conditions as in Example 1. The results are shown in Table 1.

Comparative Example 1 An electrically conductive thermal transfer body was manufactured in the same manner as in Example 1 except that the moving speed of the object to be coated was changed to 3 m/sin and the thickness of the low resistance layer was formed to 5 μm. Printing was carried out under the same conditions. The results are shown in Table 1.

Comparative Example 2 An electrically conductive thermal transfer member having the same structure as in Example 1 was manufactured except that the low resistance layer was not formed. In other words, this electrically conductive heat-sensitive transfer member is composed of a high-resistance layer, a conductive layer, and a heat-melting ink layer without providing a low-resistance layer. Printing was performed on this electrically conductive thermal transfer member under the same conditions as in Example 1. The results are shown in Table 1.

Note that Table 1 shows the printing test results arranged in order of the thickness of the low resistance layer in order to clarify the effects of the presence or absence of the low resistance layer and the thickness of the low resistance layer on printing characteristics.

Table 1 As shown in Table 1, Comparative Example 2 without a low resistance layer
In this case, energy loss occurs due to the high contact resistance, and sufficient heat generation within the resistive layer is not achieved, resulting in a small print size.The contact resistance also varies widely, resulting in variations in print. The printing characteristics were very poor. On the other hand, in Examples 1 to 4 of the present invention, the print size was almost as expected, the variation in print was small, and the print characteristics were excellent.

In other words, when a low-resistance layer was provided, the variation became smaller as the thickness of the low-resistance layer increased, but the variation did not change when the thickness of the low-resistance layer exceeded 1.0 μm. . On the other hand, as the thickness of the low-resistance layer increases, the size of the print gradually decreases because the current diffusion increases. When the size of the printed character became 95 μm and the thickness of the low resistance layer became 5.0 μm, the size of the printed character became 70 μm as shown in Comparative Example 2.

If the print size is smaller than expected, you can make the print thicker by increasing the applied voltage. 75 with an applied voltage of 20V for 0.5 ms.
If an attempt is made to increase the size from μm to 100 μm, the applied voltage will have to be considerably increased, which will increase energy loss and may increase damage to the current-carrying electrode. However, the thickness of the low resistance layer is 3.0μ
In Example 3 of M, the current diffusion due to the low resistance layer is not so large and a print of 95 μm is obtained, and increasing this to 100 μm does not require a very large applied voltage, so the energy loss is not so large. Since it is not large and there is little risk of damaging the current-carrying electrode,
Judging from both the size and variation of these prints, the thickness of the low resistance layer is 0.1 to 3.0, which is practical.
[mu]m1 It can be said that it is particularly preferable to set it in the range of 0.5 to 1.0 [mu]m.

〔Effect of the invention〕

As explained above, in the present invention, by forming a low resistance layer with a thickness of 0.1 to 3 μm by spray coating, the contact resistance between the current-carrying electrode and the resistance layer is reduced, and the low resistance layer is formed with a thickness of 0.1 to 3 μm. By suppressing the current diffusion, it was possible to provide an electrically conductive thermal transfer member with good printing characteristics.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of an electrically conductive heat-sensitive transfer member according to the present invention. FIG. 2 is a cross-sectional view showing a state in which printing is performed using the electrically conductive heat-sensitive transfer member. 1... Resistance layer, 1a... Low resistance layer, 1b...
High resistance layer, 2... Conductive layer, 3... Hot-melt ink layer, 5... Current-carrying electrode

Claims (1)

[Claims] (1) Comprising a heat-melting ink layer, a conductive layer, and a resistive layer,
The resistance layer includes a high resistance layer having an electrical resistance capable of generating heat for melting the thermofusible ink when energized, and a low resistance layer having a resistance lower than the high resistance layer on the side in contact with the current-carrying electrode. In manufacturing an electrically conductive heat-sensitive transfer body consisting of a layer, the low resistance layer is formed to a thickness of 0.1 to 3 μm by spray-coating a coating material containing a resin and a conductivity imparting agent onto the high resistance layer. 1. A method for producing an electrically conductive heat-sensitive transfer material, characterized in that the material is formed in a cylindrical shape.