JPS6280092A - Thermal transfer film and production thereof - Google Patents

Abstract

PURPOSE:To improve sticking at the time of thermal transfer and obtain a thermal transfer film optimal for the use in a thermal printer, by providing a heat-fusible ink layer on one side of a base film and providing a thin layer of a fluoro polymeric resin on the other side. CONSTITUTION:A polyester film is particularly effective for use as a base film. A coating resin comprises an aqueous emulsion or solution of a fluoro polymeric resin having perfluoroalkyl groups at side chains or other resin based on methacrylic acid or the like, with a stabilizer, an inorganic fine powder, an antistatic agent or the like mixed therein, as required. The coating agent or the like mixed therein, as required. The coating agent produces an effect when being provided in the form of a thin layer, in which the solid content is preferably 0.005 to 0.5g/m<2>. To produce a thermal transfer film, for example, an unstretched film obtained by melt extrusion of a thermoplastic resin in the form of a film is coated with the coating agent, and the coated film is subjected to simultaneous or sequential biaxial stretching. After thermally treating the biaxially stretched film, an ink layer comprising a mixture of paraffin, carbon black or the like is provided on the base film on the side opposite to the anti-sticking layer provided as above.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a thermal transfer film and a method for manufacturing the same.

Recently, recording media collectively known as thermal printers have become popular due to their ease of operation and maintenance.

It has become widely used because it has excellent characteristics such as low noise. This recording method consists of forming a heat-sensitive transfer film by providing a heat-fusible ink layer on a fixed base film, and placing a recording paper, which is a transfer material, on the heat-fusible ink layer side, and then contacting a heating head on the opposite side. and pressurize the platen roll from above the recording paper. Subsequently, a heat pulse corresponding to the recording signal is applied to the heating head, and finally the heat-melting ink layer is selectively melted and transferred onto a piece of paper to form a recorded image.

(Conventional technology) In order to perform high-speed recording using such a thermal transfer method.

It is necessary to rapidly raise the surface temperature of the heating head in a very short period of time. As a result, the base film exceeds its softening point, causing a phenomenon in which part of the base film is fused to the surface of the heating head (stain phenomenon), resulting in uneven printing and problems in feeding the thermal transfer ribbon at high speeds. Recording will no longer be possible. Conventionally, as a method to prevent this stick phenomenon,
It has been proposed to provide a metal vapor deposited layer or a heat-resistant resin layer on one side of the base film to serve as a stick prevention layer. The former is achieved by a method such as aluminum vapor deposition, but it is expensive because it involves a vapor deposition process. Most of the latter use thermosetting resins, which are heat resistant but require a curing process, which limits production speed.

There were drawbacks such as insufficient adhesion to the base film and the heat-resistant resin layer peeling off easily.

JP-A-59-169878 discloses an example in which a bonding layer is interposed between the base film and the heat-resistant coating layer, and cellulose acetate is coated with a thickness of 0.2 μm to 5 μm as a heat-resistant coating. Since layers are required, coating is time-consuming, and there is a problem with the coating thickness when making a long and compact thermal transfer film ribbon by using an ultra-thin base material. JP-A-60-24995 discloses an example in which an alkoxysilane hydrolyzate is applied.

In order to effectively advance the hydrolysis reaction of alkoxysilane, we have selected a system in which various catalysts and organic solvents coexist with colloidal silica.

As described above, in the case of this example, an organic solvent-based boss coating method is used, which increases the number of steps and requires expensive explosion-proof type coat dryer equipment. Furthermore, when aiming to make the product long and compact by using an ultra-thin base material of 3.5μ or less, advanced coating technology is required, which does not improve efficiency.

(Problems and Means to be Solved by the Invention) An object of the present invention is to improve the above-mentioned stain phenomenon during thermal transfer and to provide a thermal transfer film optimal for use in thermal printers.

That is, the gist is that in a heat-sensitive transfer film in which a heat-meltable ink layer is provided on one side of a base film made of a biaxially stretched thermoplastic resin film,
On the other side of the base film, a solid content of 0.0.
This is a heat-sensitive transfer film with excellent heat-resistant stick properties, characterized by having a thin layer of 0.005 to 0.5 g/m.

Furthermore, as a manufacturing method of the present invention, the emulsion or solution of the fluoropolymer resin is coated on one side of an unstretched film or a thermoplastic resin film stretched only in one direction, and then, after drying, simultaneous biaxial stretching or the above-mentioned We propose a method for producing a heat-sensitive transfer film with excellent heat-resistant stick prevention, which is characterized by providing a heat-melt ink layer on the non-coated surface of a biaxially stretched film obtained by stretching in a direction perpendicular to the stretching direction and heat centrifugation. It is something to do.

(Function) Although various biaxially stretched thermoplastic films can be used as the base film in the present invention, polyester films are particularly effective. The film may be a crystalline resin film such as polypropylene or nylon, or an amorphous resin film such as polycarbonate polyarylate.

The coating resin in the present invention is a fluororesin polymer resin having a perfluoroalkyl group in the side chain, and includes a structure represented by the following formula ((I) or (■)) as a general formula, and includes R+ H4C1h- C=0 (I) ■ tl-+CII* -C Moth H Insect C=0 1 (■) R+ -N O=S=O R+: ll or alkyl group with 10 or less carbon atoms R2: Alkylene with 10 or less carbon atoms Group P perfluoroalkyl group having 10 or less carbon atoms n: 5
In addition to the integer of 0 or more, methacrylic acid, methacrylic ester, acrylic acid, acrylic ester, etc. can be selected as the copolymerization component. These resins can be used in the form of an aqueous emulsion or solution.

The coating agent of the present invention may contain a coating liquid stabilizer, an inorganic fine powder for adjusting slipperiness, an antistatic agent, and the like, as necessary, within a range that does not impair its function. The heat-resistant stick coating agent of the present invention is effective with a very thin layer, and the solid content is o, oos ~ 0.5 g/r.
rr is good and preferably 0.01 to 0.1 g/-.

If the coating amount is extremely large, such as 0.5 g/rrf or more, cracks are likely to occur in the coating film during the drying process after coating, and as a result, the coating layer is likely to peel off. On the other hand, if the coating amount is extremely small, such as 0.005g10f or less, the stick prevention effect will be weak.

A method for manufacturing the heat-sensitive transfer film of the present invention will be described. The heat-sensitive transfer film of the present invention is produced by applying the above-mentioned specific coating agent to a two-wheel stretched thermoplastic resin film. Although it is of course possible to use a coating film obtained by the so-called post-coating method, the method of the present invention uses thermoplastic resin in film form in order to uniformly and inexpensively coat the necessary minimum thickness. coating a so-called unstretched film melt-extruded to
Alternatively, it is an in-line coating method in which the unstretched film is coated on a uniaxially stretched film that has been previously stretched in either the vertical or horizontal direction, and then the base film and the coating layer are stretched simultaneously in the vertical and horizontal directions or in a direction perpendicular to the previous stretching. This is the best way to obtain high productivity.

In this way, a film with extremely good adhesion of the coating layer to the base film can be obtained. The coating method is not particularly limited.

A gravure roll coating method, an inverse roll coating method, a reverse roll coating method, a Meyer bar coating method, an air knife coating method, etc. can be employed. After the coating layer and base film are co-stretched, they are heat treated to provide sufficient thermal dimensional stability to withstand post-processing steps.

In order to provide a uniform coating with the necessary minimum thickness that has a stick-preventing effect at a low cost, coating is performed before stretching during the film manufacturing process, and the base film and coating layer are simultaneously biaxially stretched.

Alternatively, this can be most effectively realized by an in-line coating method in which a film stretched in only one direction is coated and then simultaneously stretched biaxially or in a direction perpendicular to the stretching direction.

The most important feature of the present invention is that the anti-stick layer can be coated in-line on the base film without an anchor treatment. This is thought to be due to. In other words, it is thought that the integration of the base film and coating agent progresses through a process in which the hydrocarbon chains in the molecular chain of the coating agent have a large interaction force with the carbon- or hydrogen-based molecules of the base film and undergo deformation together. . Also, the stick prevention effect.

It is assumed that this is due to the molecular structure of the fluorocarbon side chain of the coating agent.

As the hot-melt ink used in the present invention, a conventionally known transfer ink can be used, and carbana wax.

Lotus wax, beeswax, micro wax.

It is selected from paraffin wax, etc., and the colored substances include carbon black, cyanine blue, lake red, phthalocyanine boule, cadmium yellow, zinc oxide, etc. A thermal transfer ink with the required color is created by mixing these, and 1g to 10g is produced using the true melt coating method.
An ink layer of /rrl is applied on the opposite side of the base film to the anti-stick layer.

Example 1 and Comparative Example 1 A perfluoroalkyl acrylate resin (resin solid content: 15 imt) was applied to an unstretched polyester film with a thickness of 35 μm.
%, Manufacturer: Asahi Glass aS, Product name: Asahi Guard AG
-710) was coated with a 150-mesh gravure roll L, dried at 60°C, preheated to 85°C, and simultaneously biaxially stretched 3.0 times in length and 3.3 times in width at the same temperature. Then, heat treatment was performed at 225° C. for 5 seconds. Obtained 3
, the anti-stick coating on the 5μ film surface is 0.0
It was 6g/rd. A heat-sensitive transfer film ribbon was formed by true-melt coating the non-coated surface of the same film with a heat-melt ink consisting of paraffin wax and carbon wax at a coating amount of 2 g/rrr. When thermal transfer printing was performed using the same ribbon using a thermal printer,
Clear printing was obtained without any staining phenomenon.

When a hot-melt ink was applied to a biaxially stretched film obtained in the same manner as in Example 1 without applying the anti-stick coating, and a printing test was conducted in the same manner, a sticking phenomenon occurred and the printing was unclear. became.

Example 2 and Comparative Example 2 An unstretched polyester film with a thickness of 52μ was stretched 1.40 times lengthwise at 80°C, then gravure coated and dried in the same manner as in Example 1, and then preheated at 100°C. , 95
℃ again under the conditions of Example 1 to obtain a 3.5μ film coated with a 0.06g/m anti-stick coating.A thermal transfer ribbon was prepared in the same manner and a printing test was carried out. When this was done, clear printing was obtained without any sticking phenomenon.

In Example 2, no anti-stick coating was applied.

When a similar printing test was performed on a biaxially stretched film obtained in the same manner by hot-melt coating with a hot-melt ink, a sticking phenomenon occurred and the printing was unclear.

Example 3 and Comparative Example 3 An unstretched film with a thickness of 48μ was stretched 3.5 times lengthwise at 82°C, coated with the aqueous emulsion of the perfluoroalkyl acrylate resin of Example 1 with a 200-mesh gravure roll, and similarly After drying and stretching 4 times in the transverse direction at 90°C to obtain a 3.5μ film coated with an anti-stick coating of 0.06g/-.

A thermal transfer ribbon was prepared in the same manner as in Example 1, and a printing test was performed. Clear printing was obtained without any sticking phenomenon.

In Example 3, no anti-stick coating was applied.

When a thermal transfer ribbon was prepared using the film obtained in the same manner and a comparative test was conducted, a stick phenomenon occurred and the resulting prints were unclear.

(Effects of the Invention) The thermal transfer film obtained by the present invention is prevented from causing the stick phenomenon, and there is no peeling of the anti-stick coating film. This effect is effectively exhibited even when the thickness of the coating film is extremely thin, such as 0.1 g/rrr or less to 0.01 g/rd, so heat conduction from the thermal head of the thermal transfer film to the ink layer is also extremely effective. Transfers quickly and is ideal for high-speed thermal transfer.

Furthermore, although the anti-stick coated surface of the present invention has a high degree of water and oil repellency, it does not transfer to the film surface where the ink layer has not been processed. This has the effect of preventing images from being copied.

Claims (3)

[Claims] (1) In a heat-sensitive transfer film in which a heat-melt ink layer is provided on one side of a base film made of a biaxially stretched thermoplastic resin film, a perfluoroalkyl group is added to the side chain on the other side of the base film. A solid content of 0.005 to 0.5 g/m^2 consisting of a fluoropolymer resin having
A heat-sensitive transfer film with excellent heat-resistant stick properties, featuring a thin layer of (2) The heat-sensitive transfer film according to claim 1, wherein the biaxially stretched thermoplastic film is a polyester film. (3) An emulsion or solution of a fluoropolymer resin having a perfluoroalkyl group in the side chain is coated on one side of an unstretched film or a thermoplastic resin film stretched in only one direction, and then dried, and then simultaneously A heat-sensitive transfer film excellent in preventing heat-resistant stickiness, characterized in that a heat-meltable adhesive layer is provided on the non-coated surface of a biaxially stretched film obtained by biaxial stretching or stretching in a direction perpendicular to the stretching direction and heat setting. manufacturing method.