JP2976066B2 - Shrink film with excellent metallic luster - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shrink film excellent in metallic luster, and more particularly to a shrink film suitable for a cap seal of a bottle or a body label.

[0002]

2. Description of the Related Art Shrink films with excellent metallic luster used for bottle cap seals and body labels are 10%.
It is necessary that the above heat shrinkage is possible, and that even if the heat shrinkage is 10% or more, it has a desired appearance. For this reason, the present inventors have conducted intensive research and have found that the heat-shrinkable film has two
It has been found that a desired effect can be obtained by laminating a metal thin film via an adhesive having a dry film elongation of not less than 00%.
No. 6 ( Japanese Patent No. 1918930), Japanese Patent Application Laid- Open No. 2-43
041 ( Japanese Patent No. 197935),
No. 143487 ( JP-B-7-41700 ) ,
Although a patent application was filed as Japanese Patent Application Laid-Open No. 7-52311 (Japanese Patent Publication No. H8-15767 ) , these products are broken by a metal layer due to stress at the time of high shrinkage, causing foil dust,
There have been problems such as the inability to obtain a desired metallic luster and the lack of stability to the contents.

However, in a shrink film as disclosed in Japanese Patent Publication No. 6-28936, a large amount of foil dust is generated due to heat shrinkage, so that only a product having a low commercial value is obtained. As described in the publication, a shrink film having a heat-shrinkable film on both the front and back surfaces of a metal thin film can prevent the generation of foil dust, but has a drawback that the metal shrinkage is reduced by heat shrinkage.

In order to solve these disadvantages, the present inventor has made repeated studies, and has made the heat-shrinkable film exist only on one side of the metal thin film. It has been found that these drawbacks can be solved by laminating a high elongation resin layer on a thin film via a low elongation resin layer ( JP-A-6-143487 and JP-A-6-143487).
JP-A-7-52311 ).

[0005] By such means, a shrink film having extremely excellent metallic luster can be obtained. However, this product has a strong metallic luster even after being used for a cap seal or the like (shrink), and has a slight quality. In some cases, the heat-shrinkable film is present only on one surface, so that only the surface on which the heat-shrinkable film is present can be used for the front surface, and both front and back surfaces have to be used properly. Also,
The surface where the heat-shrinkable film does not exist is only a two-layer thin resin layer having a total thickness of several μm on the metal thin film, so when used for bottle cap sealing, if the contents of the bottle leak, There was a risk that the metal thin film would be attacked by the contents from the back of the film.

[0006]

SUMMARY OF THE INVENTION According to the present invention, all of the drawbacks of the conventional shrink film can be improved, and when heat shrunk, an elegant metallic luster can always be obtained.
It is a product that can be used efficiently as a cap seal or body label for bottles without heat and no heat shrinkage, and can be used equally on both front and back surfaces. Another object of the present invention is to provide a product capable of stably providing a high-quality cap seal or the like without being affected by a metal thin film.

[0007]

According to the present invention, a heat-shrinkable film is provided on both front and back surfaces with a metal thin film interposed therebetween.
The heat-shrinkable film on one side of the metal thin film is dried on the metal thin film via a low elongation resin layer having a dry film elongation of 20% or less and a high elongation resin layer having a dry film elongation of 100 to 800%. The above problem was solved by sticking and laminating with an adhesive or pressure-sensitive adhesive having an elongation of 200% or more.

That is, even if a heat-shrinkable film is provided on both front and back surfaces of a metal thin film, one of the heat-shrinkable films is laminated via a specific low elongation resin layer and a high elongation resin layer as described above. By doing so, it can be used with good quality even if both sides are turned upside down, and when used for cap seals etc.
The inventors have found a surprising effect of always exhibiting an elegant metallic luster, and have completed the present invention.

The other of the heat-shrinkable films is adhered to the other surface of the metal thin film with an adhesive or adhesive having a dry elongation of 200% or more via a low elongation resin layer having a dry film elongation of 20% or less. it Re is. Of course, an adhesive or adhesive having a dry elongation of 200% or more is applied through a low elongation resin layer having a dry elongation of 20% or less and a high elongation resin layer having a dry film elongation of 100 to 800%. May be done .

The thickness of the low elongation resin layer is preferably 0.3 to 3.0 μm and the thickness of the high elongation resin layer is preferably 1 to 5 μm on both sides of the metal thin film. The thickness of the elongation resin layer is preferably smaller than the thickness of the high elongation resin layer.

The shrink film of the present invention obtained in this manner is, surprisingly, a heat-shrinkable film laminated on both sides of a metal thin film, one of which has a low elongation with a low elongation. By being laminated via a resin layer and a highly elastic resin layer, the metal gloss of the shrink film becomes extremely elegant and beautiful in the form of silver and silver when both sides are heat shrunk. Can be stably used for a cap seal or the like. The presence of the low elongation resin layer does not substantially affect the heat shrinkability of the heat shrinkable film, and can completely prevent problems such as foil dust during heat shrinkage.

Further, in the present invention, the low elongation resin layer provided between the heat shrinkable film and the metal thin film is colored to have a uniform appearance without color unevenness even by a change in shrinkage. Shrink films of various colors can be obtained.

As the heat-shrinkable film, for example, polyvinyl chloride, polyethylene, polypropylene,
A heat-shrinkable film having a heat-shrinkability of 10% or more, such as polyester, may be used. As an adhesive for attaching the heat-shrinkable film, generally, an acrylic resin-based adhesive having a dry film elongation of about 200 to 1000% is used. It is preferable to use a urethane or other rubber-based adhesive, a vinyl chloride / vinyl acetate copolymer-based adhesive or a so-called pressure-sensitive adhesive, and particularly preferable to use a pressure-sensitive adhesive.

Next, the metal thin film may be made of any of aluminum, chromium, nickel, silver, tin, and other metals or alloys, and the forming method is not particularly limited. For example, it can be formed by vacuum deposition, sputtering, ion plating, or the like.

The low elongation resin layer provided on one or both sides of the metal thin film protects the metal thin film, and at the same time, does not cause the non-elastic metal thin film to be distorted due to the displacement of the adhesive layer during heat shrinkage. It helps to maintain a uniform metallic luster. Therefore, this resin is preferably formed of a resin that is relatively hard and has an elongation of 20% or less, particularly 10% or less, without change during heat shrinkage. For example, it is preferably formed of an acrylic resin, a melamine resin, a phenol resin, a urethane resin, a vinyl chloride resin, an epoxy resin, an unsaturated polyester resin, or the like having excellent metal vapor deposition characteristics.

Next, the high elongation resin layer serves to prevent foil dust and the like during heat shrinkage and to enhance the stability of metallic luster. Examples of the resin include urethane rubber and fluorine rubber. And synthetic rubbers such as polyisobutylene rubber, silicone rubber, nitrile rubber, and styrene-butadiene rubber, and natural rubbers.

The total thickness of the high elongation resin layer and the low elongation resin layer located between at least one of the heat shrinkable film and the metal thin film is 1/5 of the thickness of the heat shrinkable film. Hereinafter, it is particularly preferable to set the value to 1/10 or less.

The shrink film of the present invention may be produced by any method, but as shown in the following examples,
It is preferably formed by a transfer method.

[0019]

Next, the present invention will be described in more detail with reference to examples. The thickness shown in the examples is
Each is the thickness of the dry film. Example 1 Mitsui Toatsu's Olester NL2472-221 (urethane elastomer, dry film elongation 200-250%) 15% / Slip Aid S on one side of polyester film # 12
The L-280 liquid was coated to a thickness of 2 μm by a gravure coating method, and an acrylic / urethane resin (dry film elongation: 10%) was further coated thereon by the gravure coating method.
A low elongation resin layer having a thickness of 5 μm was formed, and then aluminum was evaporated to a thickness of 500 to 600 ° using a vacuum evaporation machine.
Further, a polyester / urethane resin (dry film elongation: 10%) colored with a dye was applied to the aluminum vapor-deposited surface by a gravure coating method to form a low elongation resin layer having a thickness of 2 μm. Next, a heat-shrinkable vinyl chloride film (thickness: 30 μm) having a heat-shrinkage rate of 60% or more was bonded with a 20% liquid adhesive (Corponyl 8020 manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), and then the polyester film # 12 was peeled off. . The same heat-shrinkable vinyl chloride film (30 μm
Thickness) was applied to obtain a desired shrink film having excellent metallic luster. When this shrink film was heat-shrinked as a cap seal for sake with a margin of 20%, the cap seal was able to be well-fitted with both excellent metallic luster and design, regardless of whether it was turned upside down. . In addition, even if either of the front and back surfaces came in contact with the contents and the like, they could always be used stably.

Comparative Example 1 A shrink film having heat-shrinkable films on both front and back surfaces was obtained in the same manner as in Example 1 except that the high elongation resin layer and the colored low elongation resin layer were not formed.

Comparative Example 2 A method similar to that of Example 1 was used except that the heat-shrinkable film was not stuck on the high elongation resin layer and the colored low elongation resin layer was not formed. A shrink film having a heat shrinkable film was obtained.

Using the shrink films obtained in Example 1 and Comparative Examples 1 and 2, a cap seal test was performed by heat shrinkage of 40%. Table 1 shows the results.

[0023]

[Table 1]

As is clear from Table 1, the product of Example 1 according to the present invention was excellent in metallic luster, design and center sealability, and was very easy to handle. .

[0025]

The shrink film of the present invention is excellent in heat shrinkability on both front and back sides, and always retains an elegant and stable metallic luster. It can be used without producing dust. In addition, both surfaces are chemically stable and can be used efficiently.

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI B65D 71/08 B65D 71/08 A

Claims (3)

(57) [Claims] 1. A laminate comprising a heat-shrinkable film on both front and back sides of a metal thin film, wherein a low elongation resin layer having a dry film elongation of 20% or less is provided on one surface of the metal thin film. A high elongation resin layer having a dry film elongation of 100 to 800% is provided, and the high elongation resin layer has a dry elongation of 20 to 800%.
One of the heat-shrinkable films is adhered via an adhesive or pressure-sensitive adhesive of 0% or more, and the other of the heat-shrinkable films is dried on the other surface of the metal thin film.
Dry elongation of 20% through a low elongation resin layer having an elongation of 20% or less
A shrink film excellent in metallic luster characterized by being stuck with 0% or more of an adhesive or a pressure-sensitive adhesive . 2. A low elongation resin layer having a dry film elongation of 20% or less and a high elongation having a dry film elongation of 100 to 800%, wherein the other of the heat shrinkable films is formed on the other surface of the metal thin film. The shrink film according to claim 1 , wherein the shrink film is adhered with an adhesive or a pressure-sensitive adhesive having a dry elongation of 200% or more via a resin layer. 3. The low elongation resin layer has a thickness of 0.3 to 3.0 μm.
In m, the thickness of the high elongation resin layer is 1 to 5 [mu] m, and that claim 1 or, wherein the thickness of the low elongation resin layer is thinner than the thickness of the high elongation resin layer 3. The shrink film according to 2.