JPS61277486A - Pressure-sensitive thermal transfer material - Google Patents

Abstract

PURPOSE:To enhance transfer performance, by providing a pressure-sensitive thermal ink layer comprising a resin, an oil incompatible with the resin and a heat-conductive substance and/or an electrically conductive substance as main constituents on a base. CONSTITUTION:A resin, an oil incompatible with the resin and a heat-conductive substance and/or an electrically conductive substance are agitated and ground together with a solvent to prepare an ink composition. The composition is applied to the base, and is dried to provide the ink layer on the base, thereby obtaining a pressure-sensitive thermal transfer material. The base is a plastic film or the like, and the resin is preferably Versamid-711, which is a dimer acid polyamide produced by Henkel Japan, Ltd. The heat-conductive substance is typically carbon black, while the electrically conductive substance is typically a dye such as Ketjen Black, a powder of a metal such as iron and copper, or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION C. Industrial Application Field The present invention relates to a novel heat-sensitive pressure-sensitive transfer material. More specifically, by incorporating a thermally conductive substance and/or an electrically conductive substance in the ink layer and heating the ink layer, the ink layer is made to exhibit good transfer performance even with extremely weak impact pressure and low impact energy. This invention relates to a new heat-sensitive pressure-sensitive transfer material.

[Prior Art] Conventionally, typewriters that print using impact pressure from a type bar or print pole have been widely used.
Various pressure-sensitive transfer materials such as collector ink ribbons used for printing are also known.

However, in recent years, there has been an increasing demand for low-noise printing operations, and tie platers that use daisy wheels instead of the type bar or print pole described above have become widely adopted.

A typewriter using a daisy wheel is similar to a typewriter using a type bar or print pole.
This is not a printing method in which the type is hit with strong impact pressure as in the case of the above, but an impact method in which the type is pressed lightly is suitable for reducing noise, but even this method still satisfies the requirements for low noise. However, efforts are being made to further reduce impact pressure and impact energy.

[Problems to be Solved by the Invention] By the way, pressure-sensitive transfer materials that have been proposed in the past, such as the above-mentioned collector pull ink ribbon, generally use a film-like base material, and a film-forming resin is coated on the base material. In addition, it is composed of laminated ink layers whose main component is oil, which is substantially incompatible with the resin. When printing, transfer defects such as missing characters often occur, making it difficult to obtain a satisfactorily clear printed image. Furthermore, when printing is performed with such weak impact pressure or low impact energy, the printed image obtained on an adherend such as paper is a state in which the printed image is only weakly attached to the surface of the adherend. Therefore, a problem arises in that the printed image easily peels off when a force such as friction or bending is applied.

An object of the present invention is to solve the above-mentioned problems and provide a transfer medium with excellent transfer performance that can form a sufficiently clear printed image even when printing with weak impact pressure or low impact energy. As a result of the inventor's intensive research to achieve the above object,
The present invention was completed based on the discovery that it is extremely effective to include a thermally conductive substance and/or an electrically conductive substance in the ink layer and heat the ink layer to achieve the above object.

[Means for Solving the Problems] The present invention that achieves the above object mainly includes a resin, an oil substantially incompatible with the resin, a thermally conductive substance, and/or an electrically conductive substance, on a base material. This is a heat-sensitive pressure-sensitive transfer material characterized by comprising a heat-sensitive and pressure-sensitive ink layer as a component.

The present invention will now be described in detail; however, the following discussion of the effects of specific materials is provided to the best of the present understanding since the complete interactions of these materials are not fully understood. It is something.

The ink layer of the heat-sensitive pressure-sensitive transfer material of the present invention contains a resin, preferably a film-forming resin, and an oil substantially incompatible with the resin, as in conventional pressure-sensitive transfer materials. is included. In pressure-sensitive transfer materials, the oil described above is thought to have the function of making the resin brittle and easily crushed, and forming a thin layer at the interface between the ink layer and the base material to bring the ink layer and base material into close contact. ing. Also, at the time of impact, the boundary layer of the oil causes cohesive failure.

It is believed that the ink layer adheres to the adherend and printing is performed.

The heat-sensitive pressure-sensitive transfer material of the present invention contains a thermally conductive substance and/or an electrically conductive substance in the ink layer in addition to the above resin and oil.

By heating such an ink layer during printing, the viscosity of the oil in the ink layer is reduced, and even with weak cohesive failure, i.e., weak impact pressure or low impact energy, the ink layer migrates to the adherend side, i.e., printing. It is thought that this makes it easier to transfer images and prevents transfer defects such as missing characters.

In addition, due to the reduction in the viscosity of the oil due to the heating of the ink layer, when the ink layer transfers to the adherend, the oil oozes out to the interface between the adherend and the ink layer, and this reduced viscosity oil causes the oil to be covered. It seems that the adherend and the ink layer are firmly adhered to each other, and the ink layer is prevented from peeling off from the adherend after printing.

When constructing such a heat-sensitive pressure-sensitive transfer material of the present invention, a wide variety of base materials of various materials and shapes can be used, such as known plastic films used in conventional pressure-sensitive transfer materials. Preferably, for example, polyethylene,
polypropylene.

Examples include plastic films with relatively good heat resistance such as polyethylene terephthalate and aramid. Considering heating efficiency and the like, the thickness of the base material is preferably about 5 to 15 μm in the ink layer lamination direction.

The resin contained in the ink layer laminated on the base material is
Preferably, a hard resin rather than a waxy one is used, and more preferably a film-forming resin having a high degree of flexibility that can impart an appropriate cohesive force to the ink layer.

Specific examples of such resins include, for example, Persamide 711 and Persamide 725 manufactured by Henkel Japan, Emery 1533 and Emery 1548A manufactured by Emery Kogyo Co., Ltd.
These resins themselves have specific physical and chemical properties, as will be readily understood by those skilled in the art, such as Polymide S-150 manufactured by Sanyo Chemical Industries, Ltd. and Ultramid IC manufactured by Buffs. but preferably has a softening point of 100°C to 130°C, an amine value of less than 3.0 milligrams of KOH per gram, and 5.0 milligrams of KOH per gram of Ig.
Those having an acid value of milligrams or less are preferred. Among them, Persamide 711 manufactured by Henkel Japan, which is a dimer-based polyamide, has a softening point of 115°C to 125°C and a softening point of 20°C.
Particularly preferred are resins having a viscosity at 0° C. of 4 poise to 7 poise, an amine value of KO) + 2°θ milligrams per Ig, and an acid value of 5.Q milligrams of KOH per gram.

Examples of the oil used with the above resin include polyethylene glycol and n-paraffin.

Examples include one or a mixture of two or more of linseed oil, rapeseed oil, lecithin, castor oil, cottonseed oil, butyl stearate, isocetyl stearate, and the like. Preferably, it has a molecular weight of about 200 to 1000, a relatively high viscosity at room temperature, and a temperature characteristic such that the viscosity decreases at a heating temperature of about 50°C to 100°C. More preferably, the molecular weight is about 500 to 800,
The oil has a viscosity of 50 to 300 centipoise at room temperature and 5 to 40 centipoise at 50 to 80°C.

In addition to the above-mentioned resin and oil, preferably 10% to 30% by weight of a thermally conductive substance and/or an electrically conductive substance as referred to in the present invention is mainly used to facilitate the temperature rise of the ink layer during printing. It is contained in the ink layer within a certain range.

Specifically, the thermally conductive substance and the electrically conductive substance are carbon black as the thermally conductive substance, dyes such as Ketjen black, and metal powders such as iron, copper, and aluminum.

Typical examples include magnetic powder such as γ-ferrite and graphite. These substances can be used alone or in a mixture of two or more, but preferably have a function as a coloring agent, and carbon black is a thermally conductive substance, and γ is a conductive substance.
- Ferrite is particularly preferably used. Of course, these substances can be used in any form, but in view of their dispersibility in the ink layer, they are preferably in powder form, and preferably have a particle size of 20 angstroms to 500 angstroms.

The ink layer of the heat-sensitive pressure-sensitive transfer material of the present invention is mainly composed of the resin, oil, thermally conductive substance, and/or conductive substance as described above, and the thickness of the ink layer laminated on the base material is A suitable length is about 1 to 5 μs. Of course, there is no problem in adding various additives used in conventional pressure-sensitive transfer materials to the ink layer, if necessary.

The heat-sensitive transfer material of the present invention can be used in various forms, such as an ink ribbon, but methods of heating the ink layer during printing include, for example, a method using heating means such as a heater, and a method using electrical heating. method etc. can be used. Specifically, if a heater is used, for example, the printed portion of the heat-sensitive transfer material of the present invention formed as an ink ribbon, preferably the back surface of the substrate of the printed portion (i.e., the side facing the adherend) On the opposite side), attach a heater of desired shape and capacity (for example, area 1 cm, thickness 1 mm) so that its center is in close contact with the back of the substrate, preferably within about 1.5 cm from the printed area. If it is carried out by heating with electricity, for example, by contacting the electrodes from the ink layer side before and after the printed part of the ink ribbon, preferably with an electrode spacing of about 20 mm. It is preferable to perform heating, but of course, there is no problem in using both electrical heating and heating with a heater or the like.

[Example] Examples of the present invention are shown below.

[Example 1] Ink composition I Ingredients Parts by weight Resin (Persamide 725) 20 Oil (Standard #34) 40 (
Butyl stearate) 30 Carbon black lacking a thermally conductive substance) 15 - Conductive substance (
γ-ferrite) 20 After dissolving 20 parts by weight of Persamide 725 in a mixed solvent consisting of about 4/5 of Impropatol and about 1/5 of toluene, Standard #34, butyl stearate, and carbon were added to this. The above ink composition having a uniform composition was obtained by adding the above-mentioned amounts of Brassile and γ-ferrite and stirring and pulverizing the mixture in an attritor for 24 hours. The heat-sensitive pressure-sensitive transfer material of the present invention formed as an ink ribbon was obtained by coating this on a high-density polyethylene film with a thickness of 17 μs and drying it, and then cutting it into 811 mm width. has a dry weight of approximately 3 g/l
n'.

[Example 2] □ Ink ribbon ■ Ingredients Weight parts Resin (Persamide 725) 43 Oil (polyethylene glycol) 50 Conductive substance (Kerachetsu Black)
15 An ink ribbon was prepared in the same manner as in Example 1, except that the ink composition was formulated as described above.

[Example 3] Ink composition ■ Ingredients Weight parts Resin (Persamide?25) 43 Oil (linseed oil) 50 Conductive substance (
Graphite) 20 An ink ribbon was prepared in the same manner as in Example 1, except that the ink composition was formulated as described above.

[Example 4] Ink composition - Ingredients Parts by weight Resin (Persamide 725) 50 Oil' (polyethylene glycol) 80 Thermal conductive substance (carbon black) 20 Conductive substance (fine iron powder) 10 Ink composition formulation An ink ribbon was produced in the same manner as in Example 1 except that the steps were as described above.
' After mounting each of the ink ribbons of Examples 1 to 4 obtained as described above on a daisy-wheel type electronic typewriter (APAOO made by Canon (I)), 'the electrodes were placed in one contact as described above. 2 to 25 m J/
Printing was performed with an impact energy of "mrn" to obtain a printed image on the transfer paper.The printing temperature was set by heating with electricity so that the surface temperature of the ink layer of the ink ribbon was in the temperature range of 60°C to 80°C. I did it.

As a result, for all of the ink ribbons of Examples 1 to 4, good printed images with no transfer defects such as missing characters were obtained on the transfer paper with a low impact energy of 2 mJ/mrn'. Needless to say, good printed images were obtained over the entire range of impact energy, and the noise during printing was at most 50 decibels.

On the other hand, when printing is performed using a conventional ink ribbon with the typewriter described above without heating with electricity, at least one
An impact energy of 5 mJ/mrn' was required. With impact energy less than this, it was not possible to obtain a good printed image. The noise levels were also at a high level of over 75 decibels. , , As mentioned above, in the heat-sensitive pressure-sensitive transfer material of the present invention, the impact energy is substantially reduced to about one-eighth to one-tenth of that of conventional pressure-sensitive transfer materials. Since the noise is also reduced to about 1/2', the heat-sensitive pressure-sensitive transfer material of the present invention is extremely useful in daisy-wheel type typewriters, which are currently required to have low noise.

[Effects of the invention] Above 1. As described above, the present invention has made it possible to provide a novel heat-sensitive and sensual positive transfer material that eliminates transfer defects such as noise and missing characters in conventional pressure-sensitive transfer materials.

Claims (1)

[Claims] (1) A heat-sensitive and pressure-sensitive ink layer whose main components are a resin, an oil substantially incompatible with the resin, a thermally conductive substance, and/or an electrically conductive substance is provided on a base material. Heat-sensitive pressure-sensitive transfer material.