JPS62286789A - Thermal transfer recording material - Google Patents

Abstract

PURPOSE:To stabilize the running property of a base material, by roughening the surface on the side opposite to a heat-meltable ink layer forming surface of the base material formed from a synthetic resin having fine particles added thereto and specifying the center line average roughness of said surface. CONSTITUTION:A base material 1 is prepared by forming a synthetic resin 1a such as polyester having fine particles 1b added thereto into film of which the surface on the side opposite to a surface having a heat-meltable ink layer 2 formed thereto is roughened by projections 1c based on fine particles 1b. As the synthetic resin, polyester or polybutylene terephthalate is used and, as the fine particles, calcium carbonate and silicon oxide are used. The particle size of these inorg. fine particles is usually 0.05-0.6mum and the addition amount thereof is 0.5-60pts. by wt. of 100pts. of the synthetic resin. The film is formed under a usual molding condition and the surface roughness of the base material is set to 0.05-0.3mum as center line average roughness. By this method, the contact area of the base material with the thermal head of a printer becomes small and the running property thereof can be improved.

Description

[Detailed description of the invention] 3. Detailed description of the invention [Industrial application field] The present invention relates to a thermal transfer recording material.

[Conventional technology]

Conventional thermal transfer recording materials were not required to print at particularly high speeds, and simply ran through the printer's running system, so little attention was paid to the reliability and constant speed of their running. As shown in FIG. 3, the structure was such that a hot-melt ink layer 2 was formed on one side of a smooth base material 1.

By the way, in order to support the future demand for color printing and the multiple use of thermal transfer recording materials due to improved printer accuracy, thermal transfer recording materials must run at high speeds, and Reliability and constant speed are required for low-speed running.

However, with conventional thermal transfer recording materials, no attention has been paid to their runnability, and since no improvements have been made to the runnability, the base material is easily exposed to the printer's thermal under high-speed running. There was a problem in that the sliding properties between the base material and the thermal head were poor, such as close contact, and as a result, the running movement of the thermal transfer recording material became inaccurate and unstable, making high-speed printing difficult.

Therefore, by providing grooves parallel to the running direction of the base material on the surface opposite to the surface on which the heat-melt ink layer is formed, the contact area between the base material and the thermal head can be reduced, and the thermal transfer recording material can be It has been proposed to improve the running performance of (for example, Japanese Patent Laid-Open No. 142187/1987).

However, according to the research of the present inventor, when grooves are provided in the base material as described above, the contact area between the base material and the thermal head is theoretically reduced, so the close contact of the base material to the thermal head is reduced. Although it is thought that running performance will be improved by reducing the amount of friction, contact with the thermal head is still made on a flat surface in areas that are not grooves, so the effect of improving running performance is small, and it is necessary to increase the effect. When the width of the grooves is increased or the gap between the grooves is narrowed, there is a problem in that the ink is no longer melted and the resolution of printing is reduced.

[Problem that the invention seeks to solve]

The object of the present invention is to solve the uncertainties in runnability that the above conventional products had and to provide a thermal transfer recording material that has stable runnability.

[Means for solving problems]

In the present invention, the surface of the base material opposite to the surface on which the heat-melting ink layer is formed;
By making the surface, that is, the surface that comes into contact with the thermal head of the printer, a rough surface with a center line average roughness (Ra) of 0.05 to 0.3μ, the contact area between the substrate and the thermal head can be increased. The running properties of the thermal transfer recording material are stabilized by reducing the size and improving the slidability between the base material and the thermal head.

The surface roughening of the base material as described above is achieved by adding fine particles to a synthetic resin and molding it into a film when producing the base material. The film formed in this manner has protrusions based on fine particles on its surface, thereby making the surface rough. By bringing the thermal head into contact with the protrusions on the film surface based on the fine particles dispersed in the film, the contact area between the base material and the thermal head is reduced, and the sliding properties between the base material and the thermal head are improved. This stabilizes the running properties of the thermal transfer recording material. Note that the above-mentioned roughening of the film surface can be done on both sides, or it can be selectively roughened on only one side by bringing one side into contact with a roller or the like to smooth it immediately after forming. You can also do that.

The thermal transfer recording material of the present invention is schematically shown in FIGS. 1 and 2. In FIG. 0, 1 is a base material and 2 is a heat-melting ink layer. The base material 1 is made by adding fine particles 1b to a synthetic resin la such as polyester and molding it into a film, the surface of which is roughened by projections 1c based on the fine particles 1b. Figure 2 shows a base material l whose surface is roughened on both sides, and FIG. Then, as described above, the protrusion IC portion on the surface of the base material 1 based on the fine particles 1b dispersed in the base material 1 is brought into contact with the thermal head. Therefore, according to this thermal transfer recording material, the contact area between the base material and the thermal head is reduced, and running properties are improved.
Since the height of the base material l is regulated so that the surface roughness of the base material l is maintained within a specific range, there is no possibility that the ink will not melt when heated by the thermal head. No deterioration of printing characteristics occurs.

The synthetic resin for forming the base material may be any material as long as it can be molded into a film and bind fine particles. Examples of such synthetic resin include polyester (polyethylene terephthalate), polybutylene terephthalate, polyethylene, Polypropylene, polyamide, cellulose acetate, polyvinyl chloride, polycarbonate, polyimide, etc. are used.

As the fine particles added to the synthetic resin, either inorganic fine particles or organic fine particles can be used, but inorganic fine particles are usually used. Examples of inorganic fine particles include carbonate fine particles such as calcium carbonate, barium carbonate, and cobalt carbonate;
Iron oxide (Fe2O2), zinc oxide (ZnO), titanium oxide (Ti02), aluminum oxide (A1203), magnesium oxide (MgO), silicon oxide (SiO2)
fine particles of total oxides such as, fine particles of sulfates such as barium sulfate, fine particles of metals such as nickel, cobalt, iron,
Alternatively, fine particles of the above-mentioned metals, carbonates, sulfates, metal oxides, etc., having a surface of a protective colloid layer such as a polymer may be used. Since these inorganic fine particles are themselves hard, they can form solid protrusions. In addition, these inorganic fine particles are firmly fixed with a synthetic resin so that they do not fall off due to contact with the thermal head (this also has the effect of scraping off dirt adhering to the thermal head).

The size of the fine particles is usually 0.05 to 0.6.
Preferably, these particles are on the order of μm in size. Even if these fine particles are small in size, they become secondary particles and contribute to roughening the surface of the base material. There isn't.

The amount of these fine particles added to the synthetic resin is 100% of the synthetic resin.
It is preferable that the amount of fine particles is 0.5 to 60 parts by weight.In addition to the above-mentioned fine particles, the synthetic resin also contains additives that are usually added during film forming, such as sodium lauryl sulfate and dodecylbenzenesulfate. Antistatic agents such as sodium fluoride and alkylphenol polyoxyethylene ether may also be added.

Film forming can be performed under normal forming conditions, and the thickness is usually about 2 to 20 μm steel. During molding, -axial stretching or biaxial stretching may be performed. Furthermore, after biaxial stretching, further uniaxial stretching may be performed.

nG fusible ink does not require anything special,
A conventional one can be used.

For example, colorants such as carbon black, waxes such as paraffin wax, microcrystalline wax, and carnauba wax, thermoplastics such as petroleum resins, etc.
Conventional heat-melting inks containing appropriate fats and other additives can be used without any restrictions.

In the present invention, the degree of roughening of the base material surface is determined according to JIS B
Center line average roughness (Ra) based on 0601: 0°05
~0.3 μm was chosen when the center line average roughness (Ra) was 0.
．． If the center line average roughness (Ra) is smaller than 0.3 μm, the running movement between the substrate and the thermal head becomes unstable during high-speed running, and if the center line average roughness (Ra) is larger than 0.3 μm, the running performance becomes stable, but the thermal head This is because contact becomes insufficient, and as a result, printing resolution decreases. Incidentally, in this field, the center line average roughness (Ra) of the surface of the base material commonly used is 0.02 to 0.03 μ area, and in the present invention, the roughness of the base material surface is particularly measured based on the center line average roughness (Ra) of the base material surface. Average roughness (
It is particularly preferable that Ra) is 0.09 to 0.2 μm.

〔Example〕

Next, the present invention will be explained in more detail by giving examples.

Example 1 35 parts by weight of calcium carbonate fine particles having an average particle size of 0.34 μm were added to 100 parts by weight of polyester, and the mixture was heated and mixed.
A polyester film having a thickness of 611 m and a surface roughened based on calcium carbonate fine particles was obtained by melt extrusion at 280°C. This polyester film was used as a base material, a heat-melting ink layer having a thickness of 5 μm was formed on one side thereof, and the film was cut into a width of 6.31 mm to obtain a ribbon-shaped thermal transfer recording material.

The centerline average roughness (Ra) of the surface of this thermal transfer recording material opposite to the surface on which the heat-melting ink layer is formed, that is, the surface that contacts the thermal head of the printer, is 0.17 μm.
It was I. The heat-melting ink used to form the ink layer was 20 parts by weight of carbon black, 65 parts by weight of paraffin wax, 20 parts by weight of carnauba wax,
It consists of 10 parts by weight of petroleum resin and 5 parts by weight of liquid paraffin.

Example 2 A ribbon-shaped G2 transfer recording material was produced in the same manner as in Example 1, except that silicon oxide fine particles having an average particle size of 0.20 μm were used in place of the calcium carbonate fine particles in Example 1. In this thermal transfer recording material, the center line average roughness (Ra) of the surface opposite to the surface on which the heat-melting ink layer is formed is 0.1.
It was 0μ sperm.

Example 3 A ribbon-shaped thermal transfer recording material was produced in the same manner as in Example 1, except that barium sulfate fine particles with an average particle size of 12 μm were used in place of the calcium carbonate fine particles in Example 1. In this thermal transfer recording material! 8. The centerline average roughness (Ra) of the surface opposite to the surface on which the fusible ink layer was formed was 0.06 μm.

Comparative Example 1 A polyester film with a thickness of 6 μm and a smooth surface was used as a base material, and one side of the film was coated with a film having the same thickness of 5 μm as in Example 1.
A heat-melting ink layer of μm is formed, cut into a width of 6.3 ms, and a ribbon-shaped! 3 A thermal transfer recording material was produced. The polyester film used as the base material had a center line average roughness (Ra) of 0°02 μm on both sides, and the center line average roughness of the surface opposite to the surface on which the heat-melting ink layer was formed in this thermal transfer recording material was 0.02 μm. Sa(Ra) is 0.02 as a matter of course.
It was μm.

Ribbon shapes of Examples 1 to 3 and Comparative Example 11 obtained as described above! 3 Load the thermal transfer recording material into the cartridge 1
Printing was performed on plain paper at a running speed of 0.3 m/sec using a printer with a thermal head of 8 dots/maa and a roll of 60 m>, and the running performance and printing characteristics were evaluated. The results are shown in Table 1. The running performance was evaluated based on the "background stain" of the transfer paper, and the printing characteristics were evaluated using the transfer area ratio. "Background stain" on the transfer paper is caused by poor sliding between the thermal head and the base material of the thermal transfer recording material, causing the ink in the untransferred area to be pushed by the thermal head and rubbed onto the transfer paper. It refers to the dirt that occurs on the transfer paper, and the transfer area ratio indicates the ratio of the size of the printed dot to the size of the dot of the thermal radar.
Measure the area of the printed dot using an optical microscope with 100 times magnification, divide it by the dot area of the thermal head, and get 10.
It is multiplied by 0. When the transfer area ratio is 100%, it can be said that the dot area of the thermal head is faithfully reproduced. The running speed adopted in the above test was eight times the normal running speed, and corresponded to so-called high-speed printing.

Table 1 As shown in Table 1, the T:3 thermal transfer recordings of Examples 1 to 3 (E) exhibited excellent running properties, with little occurrence of "scumming" on the transfer paper even when running at high speed. This is because the surface of the base material that is in contact with the thermal head, which is opposite to the surface on which the hot-melt ink layer is formed, is roughened (as mentioned above), so that the contact between the base material and the thermal head is improved. This is due to the fact that the contact area between the substrate and the thermal head has become smaller because the contact area between the substrate and the thermal head has become smaller due to the projections on the surface of the substrate based on fine particles.In contrast, the thermal transfer recording of Comparative Example 1 showing the conventional product The surface of the material that comes into contact with the base material is smooth and the contact area between the base material and the thermal head is large, so during high-speed running, the base material comes into close contact with the thermal head, and the contact between the base material and the thermal head is The 7g hardness of the paper deteriorated, and a large number of "background stains" occurred as shown in Table 1.As for the printing characteristics, the thermal transfer recording materials of Examples 1 to 3 did not have appropriate transfer area ratios. It was not inferior to the thermal transfer recording material of Comparative Example 1, which is a conventional product.

〔Effect of the invention〕

As explained above, in the present invention, by using a film with a roughened surface obtained by adding fine particles to a synthetic resin and molding it as a base material, contact between the base material and the thermal head of the printer is achieved. By reducing the area, it was possible to improve the running properties of the thermal transfer recording material.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view schematically showing an example of the thermal transfer recording material of the present invention, and FIG. 2 is a cross-sectional view schematically showing another example of the thermal transfer recording material of the present invention. FIG. 3 is a sectional view showing an example of a conventional thermal transfer recording material. 1...Base material, 1a...Synthetic resin, 1b...Fine particles, 1c...Protrusions, 2...Heat-fusible ink layer litigation Eight comparisons to the lawsuit

Claims (2)

[Claims] (1) In a thermal transfer recording material formed by forming a heat-melting ink layer on one side of a base material, the base material is a film formed by adding fine particles to a synthetic resin, and the base material The surface opposite to the surface on which the meltable ink layer is formed is roughened based on the fine particles, and the center line average roughness (Ra) of the surface is
A thermal transfer recording material characterized in that the diameter is 0.05 to 0.3 μm. (2) The thermal transfer recording material according to claim 1, wherein the fine particles added to the synthetic resin are inorganic fine particles.