JPS60210494A - Heat transfer recording material - Google Patents

Abstract

PURPOSE:To provide a heat transfer recording material which does not need treatments to be heat-resistant and is inexpensive, by using a polyethylene film having a density of not lower than 0.935 as a sheet form base. CONSTITUTION:A polyethylene film having a density of not lower than 0.935 is used as a sheet form base, in a heat transfer recording material comprising a heat transferable ink layer on the upper side of a sheet form base. A material obtained by blending a high-density polyethylene with a low-density polyethylene may also be used, provided that the density thereof is not lower than 0.935. When the polyethylene film is brought into contact with a thermal head heated to a high temperature (about 300 deg.C), the film is instantaneously melted, but it is not thermally deformed, since the density thereof is high, and the head is moved while the film is left molten. It is presumed that a sticking phenomenon does not occur because polyethylene is low in adhesiveness to the head and serves as a kind of lubricant.

Description

[Detailed description of the invention] The present invention is a printer using a thermal head.

Regarding a thermal transfer recording material used in a thermal recording device such as a facsimile q'), more specifically, in a thermal transfer recording material having a thermally transferable ink layer on the upper surface of a thin sheet support, the thin sheet support has a density of 0.935 or more. The present invention relates to a thermal transfer recording material characterized by using a polyethylene film.

Recently, thermal printers, thermal facsimiles, etc.
A thermal transfer recording material made by coating a thin support with thermal transfer ink is used to obtain a clear and robust image on the transfer paper. The principle of thermal transfer recording is as follows. That is, the transfer paper is placed on the thermally transferable ink surface of the thermal transfer recording material, and the ink is selectively heated using a thermal head in accordance with an electric signal, starting from the side of the thin support that is not coated with the ink. Then, it is melted or sublimated transferred onto the transfer paper. Recording is completed when the thermal transfer recording material and the transfer paper are peeled off.

As the thin support for this thermal transfer recording material, it is necessary to use a heat-resistant support that can withstand the high temperature (250 to 350°C) of the thermal head. A heat-resistant film such as a polyimide film or a Teflon film that can withstand the high temperature of the thermal head even if it has a melting point is recommended. Other films such as polystyrene film, polyethylene film, polypropylene film, polyvinyl chloride film, polyhynylidene chloride film, polyethylene terectrate film,
It is said that polycarbonate film has a melting point lower than the heat generation temperature of the thermal head, and when printing, a so-called sticking phenomenon occurs in which the film melts and sticks to the thermal head, making it impossible for the thermal head to run.

Therefore, in the case of a support that causes such a sticking phenomenon, JP-A No. 55-7467 discloses a method for preventing it by using silicone resin, epoxy resin, melamine resin, etc. on the surface of the support that comes into contact with the thermal head. It has been proposed that a heat-resistant protective film selected from the group consisting of , phenolic resin, fluororesin, polyimide resin, and nitrocellulose may be provided.

In addition, Japanese Patent Publication No. 155794/1984 provides a platen prevention layer.

Japanese Patent Publication No. 57-74195 discloses a plastic film provided on one side with an anti-stick layer selected from a silicon oxide layer or a three-dimensionally crosslinked layer of polyfunctional (meth)acrylates.

The present inventors have also proposed in Japanese Patent Application No. 58-23585 a method for preventing sticking by coating or impregnating a thin sheet support with wax and/or a liquid or paste-like substance at room temperature. However, such coating or impregnating operations increase the cost by one step during production.

The present inventors do not apply processes such as coating and impregnation.
As a result of intensive research into inexpensive synthetic resin films that do not exhibit the sticking phenomenon, we have discovered that there are some types of polyethylene that are conventionally regarded as a sticking material, but which exhibit the sticking phenomenon.

In other words, among polyethylenes, what is called high-density polyethylene is good, and the relationship between density and sticking +C
As a result of the study, the prefecture found that even if high-density polyethylene is blended with low-density polyethylene, if the density is 0.935 or higher, it can be used in Act 11.

Generally, polyethylene includes high-density polyethylene (density 20, 941-0.965, melting point: 132-135°C) and low-density polyethylene: r-4-L/7 (density: 0.910-0.
．． There are two types: 940°3-melting point: 105-110°C), and each is an inexpensive material used singly or in a blend for packaging materials.

The temperature during use of the thermal head reaches about 250 to 350°C, and most of the thermoplastic resin film melts and is run in a rapidly cooled state.

However, as recent thermal printers and thermal facsimile IJs have become faster, the temperature does not drop to room temperature even when rapidly cooled, and although the temperature varies depending on the type of equipment, they still do not generate heat. It is being driven while holding it.

The sticking phenomenon between the support and the thermal head is affected by the heating and cooling temperature of the thermal head, the heating and cooling time, as well as the melting point and density of the support. It also depends slightly on whether the head is being used.

In addition to the polyethylene used in the present invention, the present inventors have reviewed a wide range of materials for the support, but polypropylene film ranks second to polyethylene film at 4-4 points, and other films cannot be put to practical use. A sticking phenomenon occurred to some extent. Although polypropylene film may be used alone, it is conceivable that it may be used as a blend with polyethylene in the present invention. In addition, in the present invention, the density of polyethylene is important, and the density is 0.9.
As long as the condition of 35 or more is not exceeded, additives other than polyethylene, such as other synthetic resins, anti-oxidant agents, lubricants, organic and inorganic pigments, etc. may be added.

The reason why the polyethylene film of the present invention does not cause the sticking phenomenon is considered as follows.

When the polyethylene film of the present invention comes into contact with a thermal head heated to a high temperature (approximately 300°C), the film melts instantaneously, but due to its high density, it does not deform due to heat. First, the thermal head melts the polyethylene before it is run. Since polyethylene is a material with low adhesion to the head, it is presumed that it acts as a kind of lubricant and does not cause the sticking phenomenon. vice versa,
The sticking phenomenon occurs in polyethylene terephthalate film because when it is heated and melted (melting point approximately 250°C) by a thermal head and then rapidly cooled, the temperature of the thermal head drops to below the melting point. It is believed that the molten material solidifies, which causes poor running due to adhesion.

In this way, when the thermal head runs, that is, during rapid cooling, if the support is still in a molten state, it is thought that the sticking phenomenon is unlikely to occur.

Polyethylene other than the one according to the present invention, that is, when the density is lower than 0.935, melting and deformation occurs at the same time as heating with a thermal head, and the deformed material traces the movement of the thermal head, making it unsuitable for practical use.

As described below, the support of the present invention has great industrial significance because it does not require heat-resistant treatment and can provide inexpensive thermal transfer recording materials.

Next, as the thermal transfer ink layer of the present invention, a conventionally known ink layer can be used as is, and is not particularly limited.

That is, the thermal transfer ink layer includes: (1) a heat-melting ink containing a colorant (carbon black, oil black, yellow pigment, magenta pigment, cyan pigment, etc.), (2) a leuco dye that is colorless at room temperature, and a leuco dye that is colorless at room temperature; A color-forming thermal transfer ink mainly containing a color developer that develops a dye, 6)
There are three known types of sublimation heat transfer inks that mainly contain a heat sublimation dye along with a binder;
Either can be used. (2), (2), 0) No matter which method is used, there is no difference in the degree of sticking between the thermal head and the support.

Example 1 High-density polyethylene with a density of 0.965 (manufactured by Mitsubishi Kasei)
and low density polyethylene with a density of 0.924 (Mitsubishi Kasei, 1
3! Films with a thickness of 10 μm and a density of 0.924 to 0.965 were prepared using a silica film at various mixing ratios. On the surface of this film, a hot melt ink containing 12% carbon black and having a melting point of 65° C. was applied at 3.5 P/m′ using a hot melt coater.

The ink on this thermal transfer film is applied to plain paper (manufactured by Mitsubishi Paper Mills,
Thermal facsimile IJ tester (manufactured by Matsushita Electronics Components ■) was placed on the image receiving paper for thermal transfer paper (trade name: TTR-T) from the uninked side (back side) to print pulse width 0.8. 1.0. 2.0 ms, voltage 16.
A completely black pattern was printed under OV conditions.

The sticking evaluation method is pulse width 0.8°1.0
, Runability (ease of movement of the support) at 2.0 milliJ seconds was rated as ○...Good, △...fair to poor.
×...Evaluated as poor and listed in Table 1.

The results show that a density of 0.936 or higher is good, especially for blended products of high-density polyethylene and low-density polyethylene.
For example, it has been confirmed that a value of 0.949 or higher is good for a fourth grade.

9- Table 1 "Example 2 Using a 10μ high-density polyethylene film with a density of 0.960, the hot melt ink of Example 1 was applied to the surface of this film at 3.5ψ/m", and the film had a density of 6.0 -/- Finished with slits on the width.

This slit-finished ribbon was loaded into a thermal type electric typewriter BP-20 manufactured by Brother Industries, Ltd., and printed using the image-receiving paper TTR-T in Example 1.

The ribbon ran smoothly without any stick noise, and the transferred characters were sufficiently dark (optical density 1.20). Although the standard thermal ribbon attached to this EP-20 uses heat-resistant treated polyethylene terephthalate as a support, it has been demonstrated that the inexpensive product of the present invention can also be used satisfactorily.

For comparison, similar experiments were conducted using a commercially available 10μ low density polyethylene film (density 0.918) and a 10μ polyethylene terephthalate film.

As a result, in the case of 10μ low-density polyethylene, the head does not run at all, and in the case of 10μ polyethylene phthalate film, the head is a serial head, so it somehow runs ~, the stick noise is loud, and the printed area is enlarged. When I tried it, I found that the film had a frosted image due to unevenness.

In addition, there was polyethylene terephthalate residue attached to the head, and it was determined that it would not be able to withstand long-term use.

Claims (1)

[Claims] 1. In a thermal transfer recording material having a thermally transferable ink layer on the upper surface of a thin sheet support, the thin sheet support has a density of 0.9
A thermal transfer recording material characterized by using a polyethylene film of 35 or more.