JPS6039024B2 - Film for vacuum deposition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum deposited film having a smooth surface and high vacuum deposited film adhesion strength.

Because polyester film has good heat resistance, high mechanical strength, and relatively high adhesion strength of vacuum-deposited films, it is possible to form a ferromagnetic deposited thin film of iron, nickel, cobalt, etc. on its surface. obtain magnetic recording media,
Gold thread, by forming a vapor-deposited thin film of aluminum, silver, gold, etc.
Although silver threads and the like can be obtained, polyester itself inherently has poor lubricity, so surface lubricity is obtained by making polymerization catalyst residuals or added fine particles protrude from the film surface during film production.

With such surface texture methods, it is difficult to control the surface condition with high precision, and a high degree of smoothness, such as that of video magnetic tape, is required, as well as fine surface roughness. In some cases, it may not be possible to obtain sufficiently desirable characteristics with the polyester film alone, and in such cases, methods of forming another resin layer on the surface of the polyester film to control the surface are being considered. However, problems such as the adhesion of the resin layer formed to the polyester film, the adhesion between the resin layer and the vapor-deposited film, the heat resistance, and mechanical strength of the resin layer arise, and it is difficult to obtain a resin layer that satisfies all of these issues. Ta. The inventors of the present invention investigated various materials for forming the resin layer, and found that an ultraviolet-curable epoxy resin layer reaction-polymerized with a Lewis acid is most suitable for this purpose.

That is, the present invention relates to a film for vacuum deposition characterized in that a UV-curable epoxy resin layer is formed on the surface of a polyester film. In the present invention, the term "vacuum evaporation" refers to depositing various materials from a vapor state in a vacuum (low pressure) to form a film that will serve as a substrate. It also includes.

The above-mentioned ultraviolet curing epoxy resin refers to an epoxy resin composition that is ionically polymerized by ultraviolet irradiation.For example, an epoxy prepolymer and an epoxy monomer mixed varnish are combined with a halide that has the property of producing a Lewis acid upon ultraviolet irradiation. An example of this is an eboxy resin composition obtained by mixing a rust body with an aromatic diazonium salt catalyst solution and then polymerizing it by UV irradiation.The above varnish and catalyst solution are commercially available from Asahi Denka Kogyo ■ under the trade name Ultraset. This is what is being done.

In addition, various additives such as an antioxidant, a heat stabilizer, a polymerization rate regulator, an antistatic agent, a leveling agent, and a lubricant can be added to this product as necessary. The eboxy composition before polymerization is in the form of a low-viscosity liquid at room temperature, and can be easily coated as it is to a thickness of about 1 to 5 mm using a commercially available industrial coating device. In order to further reduce the thickness of the pus, it is sufficient to dilute it with a solvent and apply it, then evaporate and remove the solvent, and then polymerize. The greatest effect of the present invention is that the adhesion strength of the vapor-deposited film of this ultraviolet-polymerized epoxy resin layer is extremely high. Although the reason for this is not clear, it is thought to be unique to ultraviolet polymerization in this material. Polyester films manufactured for photographic use also have significantly improved surface smoothness. However, in such a smoothed polyester film, the adhesion strength of the vapor deposited film is low and it easily peels off in a peel test using cellophane tape. The deposited film can even withstand a sellotape peel test. The second effect of the present invention is that the adhesion strength of the epoxy resin layer to the polyester film is high. The thickness of the ultraviolet-curing epoxy resin layer can be determined appropriately taking into account the thickness of the underlying polyester film, the material of the deposited material, the characteristics of the final object, etc., but if only the adhesion strength is to be improved, the thickness is 0.
Even just one mountain can accomplish that purpose. In addition, the surface roughness of the underlying polyester film is Ra = 0.7 to 1.
．． 0, and if only one side is to be mirror-finished, a film thickness of 4 to 8 degrees or more is required. Examples of the present invention are shown below.

Example 1 100 parts by weight of epoxy varnish (B6136J, manufactured by Asahi Denka Industries, Ltd.) and 3 parts by weight of a curing catalyst (PS-33, manufactured by Asahi Denka Industries, Ltd.) were applied to the surface of a photographic polyester film with a thickness of 25 mm.
The liquid containing the added parts by weight was applied to a thickness of about 3 cm using a gravure coater, and then coated with an ultraviolet lamp with an output of 80 W/arc to a thickness of about 3 cm.
Polymerization was performed by irradiation for seconds to form a thin layer of epoxy resin.

Vacuum deposition on the surface (degree of vacuum: 1 x 10-5 Torr)
A metallic cobalt thin film (thickness of about 0.1 mm) was formed by the following steps. The appearance of this item shows a specular luster, and is very clear. No peeling of the Aoi film was observed in the tape peel test.
Furthermore, when this sample was pulled by about 10%, many cracks were generated in the resin layer extending in the direction perpendicular to the pulling direction, but no peeling of the Aoi film on the resin layer was observed, and the polyester film and resin No peeling occurred between the layers. Comparative Example The resin layer formation in Example 1 was omitted, and a cobalt vapor deposited film was directly formed on the polyester film under the same conditions.

The surface of this product also had a specular gloss, but peeling of the deposited film was observed as a result of a cellophane tape peeling test. Example
2 In Example 1, the epoxy resin liquid was mixed with acetone solvent.
When a diluted epoxy resin was used, the thickness of the epoxy resin layer after curing was approximately 0.1 mm.

After forming a cobalt thin film on this material in the same manner as in Example 1, a cellophane tape test was conducted. No peeling of the vapor deposited film was observed, and numerous cracks were generated in the vapor basket film by 10% tension, but the vapor deposited film No peeling from the polyester film was observed. In the above examples, a photographic polyester film with a smooth surface was used because it was thought that this film had the lowest adhesion strength to the thin epoxy resin layer among the polyester films. Therefore, it is practically effective to apply the method to tensilized polyester film, which has a larger surface phase degree and is difficult to improve. As is clear from the above, the film for vacuum deposition of the present invention has excellent surface properties and deposition film adhesion, and is therefore very suitable as a substrate for thin-film magnetic tapes. It is also highly used as a substrate film for products.

Claims (1)

[Claims] 1. A film for vacuum deposition, characterized in that a thin layer of ultraviolet curing epoxy resin is formed on the surface of a polyester film.