JPH0739158B2 - Machine-friendly 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 mechanical self-loading shrink film excellent in metallic luster.

[0002]

2. Description of the Related Art A heat-shrinkable film having excellent metallic luster, which is used for bottle cap seals, body labels, etc., can shrink by 10% or more, and even if it shrinks by 10% or more, it has a desired appearance. It is necessary to have Therefore, in order to satisfy this requirement, the present inventor has conducted extensive studies and laminated a metal thin film on a heat-shrinkable film via an adhesive having a dry film elongation of 200% or more to obtain a desired effect. The inventors have found that they can be obtained, and applied for a patent for that (Japanese Patent Laid-Open No. 63-37931 and Japanese Patent Laid-Open No. 2-931).
-43041 gazette). Here, on the metal thin film,
It is also disclosed that a protective film is formed. However, such a shrink film is practically used in terms of heat shrinkability and metallic luster, so that it is practically used, but it has poor slipperiness with a bottle and is difficult to be automatically loaded. Therefore, its use is performed by hand, which is very inefficient and leads to an increase in product cost.

[0003]

DISCLOSURE OF THE INVENTION The present invention improves the slipperiness of such a shrink film with a bottle without sacrificing the metallic luster and heat shrinkability, and is used as a bottle cap seal or a body label. An object is to provide a product that can be efficiently and mechanically automatically loaded.

[0004]

In the present invention, a metal thin film and a non-shrinkable resin layer are sequentially laminated on one surface of a heat-shrinkable film via an adhesive layer having a dry film elongation of 200% or more. The above problems were solved by laminating a special additional resin surface layer on the non-shrinkable resin layer of the obtained laminate. This resin surface layer contains polyethylene waxes as a lubricant in a dry weight ratio of 2 to 5% by weight, and the friction coefficient-the friction coefficient between the resin surface layers-is 0.35 or less.

The shrink film of the present invention has a surface
The desired object was achieved by providing a resin surface layer having a friction coefficient as low as ever before, but such a resin surface layer is not obtained by adding a general lubricant to an ordinary protective layer.

For example, even if a silica type lubricant, which is the most common lubricant, is added to an ordinary protective layer, the friction coefficient thereof is 0.
Only 4 or more can be obtained. In such a protective layer, sufficient slipperiness cannot be obtained, and even if a large amount of a lubricant having poor slipperiness is added to forcibly reduce the friction coefficient, the protective layer However, the adhesiveness is poor and only peeling occurs.

However, when an appropriate amount of polyethylene wax is added to the resin surface layer provided on the non-shrinkable resin layer,
Its coefficient of friction (measured by the method according to JIS-K-7125-1987) can be reduced to 0.35 or less, preferably 0.3 or less, and a product that is very efficient and can be automatically loaded by a machine can be obtained. You will be able to get it. In addition,
Polyethylene waxes have a dry weight of 2 to 5 on the resin surface.
It may be added at a rate of 5% by weight.

The type of resin forming the resin surface layer is not particularly limited, and acrylic resin, urethane resin, vinyl chloride resin and the like can be effectively used.

The method of manufacturing the shrink film of the present invention is not particularly limited, and any conventional method can be used. For example, a transfer foil composed of a metal thin film and a non-shrinkable resin layer is attached by a transfer method to one surface of a heat-shrinkable film having a heat-shrinkability of 10% or more such as polyvinyl chloride, polyethylene, polypropylene, polyester, A resin surface layer is formed thereon. The thickness of the resin surface layer is 0.5-3μ
About m is sufficient.

The heat shrinkable film and the metal thin film (or the above transfer foil) have a dry film elongation (according to JIS K-7113).
By using an adhesive having a ratio of 200% or more, it is possible to obtain a product having a good quality and a uniform metallic luster even if it is shrunk. Examples of such an adhesive include an acrylic resin adhesive having a dry film elongation of about 200 to 1000%, a urethane or other rubber adhesive, a vinyl chloride / vinyl acetate copolymer adhesive, or a so-called adhesive. Can be used.

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

Further, the non-shrinkable resin layer located on the metal thin film not only prevents the metal thin film from being damaged or being invaded by the outside air, but also the metal thin film having no elasticity acts as an adhesive layer when the heat shrinks. It is useful for maintaining a uniform metallic luster without causing distortion due to displacement. Therefore, this resin layer is relatively hard and does not change at the time of heat shrinkage and has an elongation of 1
It is formed of 0% or less, preferably 5% or less of resin. For example, it is formed of an acrylic resin, a melamine resin, a phenol resin, a hard urethane resin, an epoxy resin, an unsaturated polyester resin or the like which has excellent metal vapor deposition characteristics. In the present invention, a resin surface layer containing polyethylene waxes is further formed on the non-shrinkable resin layer. Therefore, the thickness of the non-shrinkable resin layer is 0.5 to 3 μm.
It is preferably a thin layer of about m.

Incidentally, it is necessary that the non-shrinkable resin layer and the resin surface layer are selected within a range that does not substantially affect the shrinkability of the heat-shrinkable film which is the main component of the shrink film of the present invention. Of course, normally, the total thickness of the non-shrinkable resin layer and the resin surface layer is preferably set to 1/5 or less, particularly 1/10 or less of the thickness of the heat-shrinkable film.

[0014]

EXAMPLES The present invention will be described in more detail with reference to Examples. The friction coefficient in the Examples is JIS-K-
It measured by the method according to 7125-1987. Example 1 A release layer having a thickness of 1 μm was formed on one surface of a polyester film by a gravure coater, and a thickness of 1.5 μm was formed thereon.
m acrylic-urethane layer (non-shrinkable resin layer), thickness 4
A transfer foil provided with an aluminum vapor deposition layer of 00-500Å was prepared, and an adhesive having a thickness of 3-5 μm (Takelac A-975 and Takenate A-3 manufactured by Takeda Pharmaceutical Co., Ltd. was prepared on the transfer foil.
Was applied-a dry film elongation of 440%), and a heat-shrinkable polyvinyl chloride film having a thickness of 60 μm was laminated. Next, the polyester film having a release layer was peeled from this laminate, and a vinyl chloride resin (Hostaflex CM131 manufactured by Hoechst Co.) was further applied to the transfer foil surface side of the obtained film with a gravure coater. A resin surface layer having a thickness of 1 to 2 μm was formed. As shown in Table 1, this resin surface layer was applied by changing the kind and amount of lubricant added, to produce 18 kinds of heat-shrinkable films. The results of testing the adhesiveness of the resin surface layer and the friction coefficient between the resin surface layers of the obtained heat-shrinkable film are shown in Table 1 together with the automatic loading property and the gloss after shrinkage.

The addition amount of the lubricant shown in Table 1 is% with respect to the solid content of the resin surface layer. The adhesiveness of the resin surface layer was evaluated by a cellophane tape peeling test. In addition, the used lubricant A ~
E is as follows. A. Polyethylene wax manufactured by San Nopco (SL-
280) B. Polyethylene waxes (Ceridust 130) manufactured by Hoechst C.I. Polyethylene waxes (Ceridust 9615A) manufactured by Hoechst Co. D. Silica-based lubricant manufactured by Nippon Aerosil Co., Ltd. (TT-60
0) E. Silica lubricant made by Nippon Aerosil Co., Ltd. (R-972)

[0016]

[Table 1]

Example 2 A heat-shrinkable film was produced in the same manner as in Example 1 except that an acrylic resin (Akrit 0502TC manufactured by Taisei Kako Co., Ltd.) was used in place of the vinyl chloride resin to form the resin surface layer. did. As the lubricant, two kinds of B and E were used. In the same manner as in Example 1, Table 2 shows the results of testing the adhesion and friction coefficient of the resin surface layer.

[0018]

[Table 2]

As is clear from Tables 1 and 2, the polyethylene wax-based lubricants added in an amount of 2 to 5% according to the present invention show very good results. Further, it can be seen that if the amount of the lubricant is too small or too large, the lubricity deteriorates, and if it is too large, there is a risk that the adhesive strength of the resin surface layer is lowered. When the heat-shrinkable film with good lubricity obtained in Examples 1 and 2 was applied to an automatic loading machine, it was loaded into the bottle very smoothly, and the content was 10 to 30%.
Even when it was shrunk, it retained the metallic luster.

[0020]

INDUSTRIAL APPLICABILITY In the present invention, in a state of excellent metallic luster,
As a bottle cap seal or body label, it is possible to efficiently obtain a shrink film that can be mechanically automatically loaded.

Claims (1)

[Claims] 1. A metal thin film and a non-shrinkable resin layer are sequentially laminated on one surface of a heat-shrinkable film having a heat-shrinkability of 10% or more, with an adhesive layer having a dry film elongation of 200% or more interposed therebetween. In the obtained laminate, an additional resin surface layer is laminated on the non-shrinkable resin layer, and the resin surface layer is 2 to 5% by dry weight of polyethylene wax as a lubricant.
And the coefficient of friction of the resin surface layer is 0. A mechanically auto-loadable shrink film having a metallic luster of 35 or less.