JPS646015B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming an uneven pattern on a biaxially stretched film.

It has been known for a long time that the design effect of a biaxially stretched plastic film can be improved by embossing a pattern on the surface of the film. In some cases, normal embossing methods cannot produce clear linear patterns,
Further, there is a drawback in that large wrinkles are formed in the film after embossing, making it impossible to obtain a good embossing film. Therefore, sandblasting was generally used to impart a hairline pattern to biaxially stretched films. However, when the above-mentioned sandblasting method is used, the thickness of the thin lines that make up the hairline pattern becomes uneven, it is difficult to form deep linear patterns with large irregularities, and processing takes a long time. There's a problem. Furthermore, the sandblasting method cannot form a wavy pattern consisting of thin lines or a pattern in which thin lines are inclined to each other.

As a result of intensive research into forming a concavo-convex pattern consisting of clear thin lines by embossing, the inventor found that a clear concavo-convex pattern was realized by embossing a plastic film with release paper attached. Moreover, they found that the film was free from wrinkles caused by embossing.

That is, the present invention is a method for forming a concavo-convex pattern on a biaxially stretched plastic film, which is characterized by attaching a release paper to a biaxially stretched plastic film and subjecting the film surface to embossing.

The biaxially stretched plastic film used in this invention is a plastic film made of polyester such as polyethylene terephthalate, polyamide such as nylon, polyolefin such as polyethylene or polypropylene, and its thickness is
It is 25-300 microns. These films are dyes,
If the film is colored with pigments or has metal vapor deposited on its surface, the design effect after embossing will be even greater.

The release paper used in this invention is a paper coated with a silicone release agent and has release properties, and the basis weight of the paper is preferably 50 to 200 g/m ² . The basis weight of the release paper is
If it is less than 50 g/m ² , the release paper may be damaged during the embossing process on the film surface, and the cushioning properties during the embossing process will decrease, and the uneven pattern consisting of thin lines will become unclear, making it less than the desired level. It is difficult to obtain something. If the basis weight of the release paper exceeds 200 g/m ² , the flexibility of the release paper attached to the biaxially stretched film will decrease, making it difficult to wind it around a roller.

In order to attach a release paper to the above-mentioned biaxially stretched film, a pressure-sensitive adhesive is applied to either or both of the film and the release paper in advance, and the films and release paper are overlapped and adhered. A preferred method is to superimpose a release paper coated with the above-mentioned adhesive on a biaxially stretched film and then wind it around a roller, but the method is not limited to the above-mentioned method.

As the above-mentioned adhesive, polyvinyl acetate, polyacrylic acid ester, polyvinyl alcohol, etc. are suitable, and the solid content of the adhesive layer is 10 to 100.
g/m ² is preferred.

Embossing is carried out on the surface of the biaxially stretched plastic film adhered to the release paper by applying pressure at an appropriate temperature and pressure with an embossing roller having an uneven pattern engraved thereon. In the present invention, a normal plain roller with a smooth surface can be used as the back roller facing the embossing roller. In addition to the embossing method described above, embossing can be performed by a known preheating method. The embossing temperature and pressure vary depending on the type of synthetic resin composing the film. For example, in the case of polyester film, the temperature is 130°C or less, preferably 60 to 90°C, and the linear pressure is 10 to 100 kg/cm, preferably 50-90
Kg/cm.

According to this invention, since the release paper acts as a cushion during embossing, it is possible to clearly form an uneven pattern consisting of thin lines, a so-called hairline pattern, on the film surface. To form a hairline pattern, each line preferably has a width of 50 to 200 microns and a depth of 5 to 100 microns. Further, according to the present invention, a hairline pattern with different linear lengths as shown in FIG. 1, a wavy hairline pattern as shown in FIG. 2, and a diamond pattern with different luster as shown in FIG. 3 are formed. can do. It goes without saying that a normal uneven pattern can be clearly formed.

Further, according to the present invention, when embossing the film surface, wrinkles do not occur on the film because the release paper is attached.
Furthermore, there is no need to directly heat or pressurize the back roller of the embossing roller, so there is no damage to the back roller, which is usually made of rubber.

The plastic film obtained by this invention can be used as a sealing label by printing a desired pattern on its surface.
Widely used for stickers, etc.

Examples of the present invention will be described below.

Example 1 A release paper with a basis weight of 120 g/m ² coated with polyacrylic acid ester as an adhesive at a solid content of 50 g/m ² is superimposed on a 50 micron thick biaxially stretched polyester film vacuum-deposited with aluminum. I wound it up on a roller. Next, a layer of 150 microns in width was applied to the surface of the laminated sheet film pulled out from the roller.
An embossing roller with closely spaced grooves of 40 microns in depth and different lengths was moved at a circumferential speed of 5 m/min and at a temperature of
Pressure was applied at 90° C. and a linear pressure of 90 kg/cm to form a hairline pattern on the film surface as shown in FIG. The hairline pattern of the obtained film was clearer than the hairline pattern formed by conventional sandblasting, and the film showed no wrinkles at all.

Note that when the release paper was not attached, wrinkles were generated in the longitudinal direction of the film due to embossing, and under the same embossing conditions as in Example 1, partial cracks were generated in the film.

Example 2 A solid amount of polyvinyl acetate as an adhesive was applied to a biaxially stretched polyethylene film with a thickness of 100 microns at a solid content of 25.
Release paper with a basis weight of 150 g/m ² was coated at 150 g/m ² and wound on a roller. Next, the surface of the film of the laminated sheet pulled out from the roller was heated to a surface temperature of 50°C with a preheater, and then passed between a room temperature embossing roller with grooves similar to those in Example 1 and a rubber roller with a smooth surface to heat the film surface. A hairline pattern as shown in FIG. 1 was formed on the wafer. The hairline pattern of the obtained film was as clear as in Example 1, and there were no wrinkles at all in the film.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a straight hairline pattern, FIG. 2 is a plan view showing a wavy hairline pattern, and FIG. 3 is a plan view showing a lattice pattern.

Claims (1)

[Scope of Claims] 1. A method for forming a concavo-convex pattern on a biaxially stretched plastic film, which comprises attaching a release paper to a biaxially stretched plastic film and subjecting the film surface to embossing. 2. The method for forming a concavo-convex pattern on a biaxially stretched film according to claim 1, wherein the concavo-convex pattern is formed by paralleling thin lines.