JPH0259387A - Resistor layer for electrothermal transfer recording medium - Google Patents

Abstract

PURPOSE:To prevent an ink from being adhered to an electrothermal resistor layer of an electrothermal transfer recording medium and enable reliability and image stability to be maintained by causing the resistor layer to comprise at least a fluoro surface active agent in a specified amount. CONSTITUTION:A fluoro surface active agent to be used in an electrothermal resistor layer is a nonionic surface active agent, preferably, a perfluoroalkylethylene oxide adduct, a perfluoroalkylpropylene oxide adduct or the like. From the viewpoint of an effect on blocking resistance, the fluoro surface active agent is preferably used in an amount of 1.0 to 5.0wt.% based on the resistor layer. It is thereby possible to prevent adhesion of an ink to the resistor layer, while ensuring satisfactory dispersion of conductive particles and maintaining a stable resistance value and application properties.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a resistive layer used in an electrical thermal transfer recording medium used in an electrical thermal transfer printer.

[Conventional technology]

Among thermal transfer recording methods, the method of generating a record by generating heat from a current-carrying resistive layer using a current-carrying head and transferring ink to the transfer paper is more advantageous in terms of recording energy than the conventional method using a thermal head. Recently, it has attracted increasing attention because it is suitable for color recording and has a fast printing speed.

And the resistance layer is polyester-based, urethane-based, epoxy-based, phenoxy-based, polyethersulfone-based,
Conductive ash carbon black and/or metal powder (conductive dispersed particles) are dispersed with various organic thermoplastic and/or thermosetting resins as a binder along with other additives such as plasticizers and dispersants. Furthermore, as disclosed in Japanese Patent Application No. 62-234016, the addition of 0.01% to 1.0% by weight of a fluorosurfactant prevents wear of the current-carrying head electrode and improves image reproducibility during long-term use. This is to maintain and ensure the following.

However, in thermal melt transfer, the main component of the ink is wax, and as the temperature rises, the wax softens, melts, and then transfers to the surface it comes in contact with, which often induces a so-called blocking phenomenon. Ta.

In particular, when the current-carrying resistance layer and the ink layer are in contact with each other in a roll form, the lipophilic nature of the current-carrying resistance layer makes it easy for the ink to adhere, causing a change in resistance value, making the concentration unstable, and If ink adheres to the paper, it has a significant impact on image quality, such as reducing transfer efficiency.

Therefore, a top layer with a high melting point was provided on top of the interlayer to prevent blocking.

[Problem to be solved by the invention]

However, in the prior art described above, the top layer itself is made of wax, although it has a high melting point, so if blocking is considered as ink adhesion, it cannot be a wood-based solution.

The present invention aims to solve this problem, and its purpose is to sufficiently disperse conductive particles by adding a fluorosurfactant to the current-carrying resistance layer, thereby achieving stable resistance values and coating properties. It is an object of the present invention to provide a resistive layer that prevents ink from adhering to a current-carrying resistive layer while maintaining reliability and image stability.

[Means to solve the problem]

The resistance layer for an electrically conductive thermal transfer recording medium of the present invention is characterized in that it contains at least a fluorosurfactant. Preferably, the content of the fluorosurfactant is 1.0% by weight or more.
It is 5.0% by weight.

[Effect]

The object of the present invention is to significantly improve blocking resistance by using a fluorosurfactant in the current-carrying resistance layer.

The fluorosurfactant used in the present invention is nonionic, and preferred examples include perfluoroalkylethylene oxide adducts and perfluoroalkylpropylene oxide adducts.

Further, in view of the effect on blocking resistance, the amount of the fluorosurfactant used is preferably 1.0% by weight or more based on the resistance layer. However, if it exceeds 5.0% by weight, it will not only reduce the dispersibility of the conductive particles but also cause the generation of bubbles, which is a characteristic of surfactants, which will deteriorate the coating properties and make it difficult to maintain a stable resistance value. It becomes difficult.

The present invention will be specifically explained below using examples.

〔Example〕

The material names of the current-carrying resistance layers according to the examples of the present invention are shown below, and the composition ratios are shown in Table 1.

Resistance layer material Carbon black: Ketchen Black Lion AKZO Baycil PE-100 Gutdeyer Tsuruspersasl Cl Polyester resin: Carbon Plaque M: Dispersant Fluorine surfactant 1) CF-150 2) Surflon 338 3) Surflon SC1 : Toagosei Kagaku 1 : Asahi Glass 01 : Asahi Glass Nao, Examples 1 to 9 and Comparative Examples 1 to 6 are:
Using the binder shown in Table 1, polyester resin and fluorosurfactant were dissolved in a mixed solution of toluene/methyl ethyl ketone/cyclohexanone = 1/1/1, and then placed in a sample bottle filled with glass beads. Carbon black was added to the mixture and dispersed in a shaker for 6 hours.

Furthermore, in Comparative Example 7, the addition of the fluorosurfactant was excluded from the above procedure.

Each of these solutions was gravure coated onto a 6 μm PET film so that the film thickness after drying was 4 μm to prepare a sample.

The ink composition used in this example is shown below.

Ink layer composition Magenta pigment: 10wt% Carnauba wax: 40t% Microcrystalline wax: 20wt% Normal paraffin wax:
24wt% ethylene-vinyl acetate copolymer: 5-t%
Pigment dispersant: 1wt% Next, as shown in FIG. 1(a), the thermal transfer ink was applied to the support layer 104.
LoCm coated area 102 and 2cm uncoated area 103 on top
was prepared and coated repeatedly as a unit. In addition, FIG. 1(a) is a locally enlarged view of FIG. 1(a).

The evaluation method is shown below.

1: Blocking resistance As shown in FIG. 1(a), the current-carrying resistance layer 101 produced by the above method is overlaid on the ink layer repeatedly coated with 102 and 103, and the 2 m length is wound around the core 105. 50°C
and left for 48 hours in an environment with humidity of 70% RH.

Furthermore, the anti-blocking performance was evaluated by subjecting the left sample to electrical transfer as follows.

First, the ink layer is removed, and as shown in FIG. 2, a thin, low-density solid color is applied to the hot paper using a resistance layer section 203 that has both an ink layer contact section 201 and a standard ink layer non-contact section 202. The degree of blocking was determined from the density reduction rate after electrical transfer.

As blocking progresses, the resistance layer portion 2 comes into contact with 102
01 has a higher resistance layer than 202 which is in contact with 103.

FIG. 3 shows the result of electrically transferring the portion 203 onto thermal paper, and shows the change in the amount of heat generated due to the difference in resistance value.

Note that 301 is the transfer result of the 201st portion, and 302 is the transfer result of the 202nd portion.

2: Dispersibility of carbon black A small amount of the current-carrying resistance layer coating solution prepared by the above method was applied onto a slide glass, and observed under a microscope with a magnification of 400 times. The evaluation criteria were as follows: The number of carbon blacks present within 0.1 mm'' that were neither aggregated nor dispersed was counted and rated as less than 5 and 0.0.5 and 0.x.

3. Coating properties When applying the current-carrying resistance layer coating liquid prepared by the above method, check for defects such as generation of bubbles, and if there are no defects, mark ○.
, If there was a problem, it was marked as ×.

The evaluation results of 1, 2.3 above are shown in Table 2.

From Table 2, it can be seen that Examples 1 to 9 of the present invention are excellent in blocking resistance, carbon black dispersibility, and coatability.

On the other hand, although Comparative Examples 1, 3, and 5 have excellent blocking resistance, they have problems such as poor dispersion of carbon black and poor coating due to the generation of bubbles.
, 6.7 had no problems in dispersibility and coatability, but the anti-blocking performance was insufficient.

It goes without saying that the present invention is not limited to these, and that similar effects can be achieved in other ways as well.

〔Effect of the invention〕

(According to the present invention, by adding a fluorosurfactant to the conductive resistance layer, the conductive particles are sufficiently dispersed, and the conductive resistance layer is coated while maintaining stable resistance value and coatability.) This has the effect of providing a resistive layer that prevents ink from adhering to the surface and maintains reliability and image stability.

[Brief explanation of the drawing]

FIG. 1(a) is a perspective view of the electrically conductive thermal transfer recording medium of the present invention wound around a core. Figure 3) is a cross-sectional view of a thermal transfer ink layer used to evaluate the current-carrying resistance layer of the present invention. FIG. 2 is a cross-sectional view showing the state of contact between the ink layer and the resistance layer when the ink layer and the resistance layer are rolled as shown in FIG. 1(a). FIG. 3 is an explanatory diagram when the portion 203 in FIG. 2 is thermally transferred. 101: Current carrying resistance layer 102: Heat transfer ink coated area 103: Iron transfer ink uncoated area 104: Support layer 105; Core 201: Resistance layer part 202 in contact with 102 = Resistance layer part 203 in contact with 103: Sensitive Thermal transfer unit 301: Transfer result of 201 302: Transfer result of 202 303: Thermal paper or more

Claims (2)

[Claims] (1) A resistance layer for a current-carrying thermal transfer recording medium comprising at least a current-carrying resistance layer and an ink layer, which contains a fluorine-based surfactant. (2) The resistance layer for an electrical thermal transfer recording medium according to claim 1, wherein the content of the fluorosurfactant is from 1.0% by weight to 5.0% by weight.