JPH06102373B2 - Heat-shrinkable sheet with excellent metallic luster - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a heat-shrinkable sheet obtained by laminating a metal thin film on a heat-shrinkable film.

As a heat-shrinkable sheet having a metallic luster, a heat-shrinkable film coated with a coating having a metallic luster, a heat-shrinkable film coated with a hard resin excellent in metal deposition characteristics,
It is known that a metal vapor-deposited after that, or a metal foil or a vapor-deposited film that does not change even at the temperature during the heat-shrinking process is attached to the heat-shrinkable film. If the shrinkage ratio is not controlled to 3% or less, there is a problem that a uniform surface condition cannot be obtained, and it is difficult to put it into practical use for mechanical loading such as a bottle cap cover.

Therefore, the inventors of the present invention have conducted intensive studies to improve such drawbacks and obtain a heat-shrinkable sheet excellent in metallic luster that can be effectively used for mechanical loading such as a cover of a bottle cap. A thin metal film is provided on one side of a flexible film via an adhesive layer with a very high degree of elongation, and a non-heat-shrinkable resin layer with a very low degree of elongation is then sequentially laminated on it. By doing so, it was found that a heat-shrinkable sheet having an appearance excellent in metallic luster can be obtained even when heat-shrinked by 10% or more, and a patent application was previously filed (JP-A-63-37931).

Problems to be Solved by the Invention The heat-shrinkable sheet of the patent application has excellent metallic luster even when heat-shrinked by 10% or more, but high shrinkage causes foil dust,
Therefore, it cannot be applied to packaging of bottle mouths that come into direct contact with foods, and the metallic luster has a poor design effect because it shines evenly over the entire surface. It was easy to have a non-appearance. Furthermore, when using it in a tubular shape, it is necessary to overlap and join both ends of the heat-shrinkable sheet, but in this joining, that is, "backing process", if a solvent is used, the adhesive layer will be attacked and delamination will occur. Since it is easy to do so, it is difficult to directly bond both ends of the heat-shrinkable sheet, and there is a drawback that special processing is required such as newly stacking heat-shrinkable tape and bonding.

Therefore, the present invention is a heat-shrinkable sheet having a metallic luster that is used for a cap of a bottle, that is, a cap seal or the like, and does not cause foil dust even when shrunk to a high level of 20% or more. It is an object of the present invention to provide a product having a uniform appearance rich in design effect and capable of performing back-pasting processing with good workability.

Means for Solving the Problems The present invention provides a heat-shrinkable film on both front and back surfaces of a metal thin film through an adhesive layer, and further, this adhesive layer has a dry film elongation of 200% or more on both front and back surfaces. And then
The thickness of the adhesive layer is 5 μm or less, and the metal thin film is formed thinner than this adhesive layer to effectively solve the above problems (the elongation in the present invention is not limited to JIS K). Indicates the value measured by −7113).

That is, the sheet of the present invention has a thickness of the adhesive layer (5 μm or less)
Thinner, for example 0.1 μm or less, 400 to 500 Å (0.04 to 0.0
(5 μm) Since the front and back sides of a thin metal thin film are covered with heat-shrinkable films, stable shrinkage is possible even if heat shrinking by 20% or more does not peel off the metal thin film and cause foil dust. Therefore, it can be used for a cap seal or the like depending on its appearance. Furthermore, since the back and back processing is made of a film due to its processability on both the front and back sides, delamination does not occur,
With general processing, strong processing can be easily performed. In addition,
The metallic luster is that since both sides of the metal thin film are covered with a heat-shrinkable film having an appropriate elongation, the metal thin film shrinks uniformly as the heat-shrinkable film shrinks, resulting in a matte finish. It will have a calm appearance.

The method for producing the sheet of the present invention is not particularly limited, but for example, one side of a heat-shrinkable film, with an adhesive having an elongation of 200% or more, a support / release layer / protective layer / metal vapor deposition layer After bonding such transfer foil, peel the support of the transfer foil, and then bond the heat-shrinkable film to the peeled surface with an adhesive having an elongation of 200% or more. it can.

In the present invention, as the heat-shrinkable film, it is preferable to use a film having a heat-shrinkability of 10% or more, and any film which is generally commercially available as a heat-shrinkable film can be applied. Examples of typical materials include polyvinyl chloride, polyethylene, polypropylene and polyester.

Incidentally, the heat-shrinkable film, it is preferable to use those having different thicknesses on the front and back of the metal thin film, generally, the thickness of one heat-shrinkable film to the thickness of the other heat-shrinkable film is 80 It is preferably selected and used so as to be thinned to -15%, particularly 60 to 20%. This is because when the heat-shrinkable sheet of the present invention is actually loaded into a bottle or the like and heat-shrinked, the heat-shrinkage occurs more strongly when the thick heat-shrinkable film is brought to the side strongly receiving heat, and the shrinkage time is longer. This is because it is fast and the appearance is tight.

Next, the adhesive layer may be formed so as to have an elongation of 200% or more in a dry film state. Generally, an acrylic resin adhesive, urethane or other rubber-based adhesive having a dry film elongation of about 200 to 10000%. The adhesive is formed using an adhesive, a vinyl chloride / vinyl acetate copolymer adhesive, or the like, but may be formed using a so-called adhesive.

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

In the present invention, it is preferable to directly provide a heat-shrinkable film on both front and back surfaces of the metal thin film via a predetermined adhesive layer. However, when manufactured by a transfer method or the like, protection generally applied at the time of forming a transfer foil. The adhesive layer may be applied to a metal thin film having layers or the like.

Example (1) A transfer foil having an acrylic-urethane protective layer having a thickness of 1 μm and an Al vapor deposition layer of 400 to 500 Å formed by gravure coating on one surface of a polyester film # 25 was prepared. A heat-shrinkable polyvinyl chloride film having a thickness of 50 μm is attached to the layer through an adhesive having a dry film elongation of 700 to 800% and a thickness of 3 to 5 μm (U-LOCK N502 manufactured by Honey Chemical Co., Ltd.). I matched it.

Next, the polyester film is peeled off, and a 2-5 μm thick adhesive (COPONYL # 8020) is further applied to the peeling surface side of the resulting beautiful silver-colored metallic luster film, and after drying, A 20 μm-thick heat-shrinkable vinyl chloride film having the same heat-shrinkage direction as the used polyvinyl chloride film is attached, and the heat-shrinkable film is provided on both sides of the Al vapor deposition layer. Sheet A with a beautiful silver metallic luster
Was manufactured.

Example (2) Takeda Pharmaceutical Co., Ltd. instead of the adhesive of Example (1)
3-4 μm of adhesive (dry film elongation 440%) in which Takelac A-975 and Takenate A-3 made in Japan were blended in a ratio of 7: 1
A sheet B having a beautiful silver metallic luster was obtained in the same manner as in Example (1) except that the sheet B was applied in the same thickness.

Comparative Example (1) Takeda Pharmaceutical Co., Ltd. instead of the adhesive of Example (1)
Takelac A-2071 and Takenate A-3 made in a ratio of 10: 1 (3% to 4μ of dry film elongation 140%)
A sheet C having a beautiful silver metallic luster was obtained in the same manner as in Example (1) except that the sheet C was applied in a thickness of m.

Comparative Example (2) A 1 μm-thick wax release layer was provided on one side of a polyester film by a gravure coater, and the wax release layer was formed thereon.
1.5μm acrylic-urethane protective layer, thickness 400 ~ 500Å
The transfer foil provided with the Al vapor-deposited layer was prepared, and the transfer foil was attached to a heat-shrinkable polyvinyl chloride film having a thickness of 70 μm via a pressure-sensitive adhesive (Corponyl # 8020) having a thickness of 2 to 5 μm. Sheet D obtained by peeling off the polyester film had a beautiful silver metallic luster.

Comparative Example (3) A 1 μm-thick wax release layer is provided on one side of a polyester film, and a urethane elastomer having a dry film elongation of 800% is applied thereon by a gravure coater so as to form a 2 μm-thick film. Then, after further providing a 1.5 μm thick acrylic-urethane protective layer, 400-500 Å thick Al
A transfer foil provided with a vapor deposition layer is prepared, and the transfer foil having a thickness of 3 to
5 μm adhesive (Honey Kasei Co., Ltd. CORLOCK N-50
2) -The dry film elongation is 700-800% -and the thickness is 70μ.
m heat-shrinkable polyvinyl chloride film. Sheet E obtained by peeling off the polyester film had a beautiful silver metallic luster.

The product sheets A to E obtained in Examples and Comparative Examples were heat-treated at shrinkage rates of 10%, 20% and 30%, respectively, to obtain metallic luster, texture,
The occurrence of foil dust, and the adhesive strength and spine processability of the spine sticking portion when used in a tubular form were examined. The results are shown in the table below.

The back-pasting process is to directly bond the overlapping surfaces of both ends of the sheet using a solvent.

From the above results, the sheets A and B according to the present invention have excellent metallic luster and calm matte texture at any shrinkage ratio (10% to 30%), and there is no foil dust at all. Further, it can be seen that the heat-shrinkable sheet is excellent in processability and can obtain excellent adhesive strength even in back-adhesion process using a simple solvent. On the other hand, the sheets D and E obtained in the comparative examples show extremely excellent metallic luster at any shrinkage ratio, but in practical use, the occurrence of foil dust, the adhesive strength and the low workability are low. It becomes a problem. In addition, even with the same configuration as the present invention, the elongation
When an adhesive of 200% or less is used (sheet C obtained in the comparative example), the metallic luster disappears and the feeling becomes poor at a high shrinkage ratio.

Example 3 A polyvinyl chloride film having a thickness of 40 μm was used as the heat-shrinkable film, the adhesive layer and the Al layer were changed as shown in Table 2, and the heat-shrinkable film / adhesive layer / Al layer / adhesive layer / heat shrinkable. A heat-shrinkable sheet having a laminated structure of a flexible film was obtained (however, A1 to A4, B1 to B4 and C1 in Table 2 are comparative examples).

The resulting heat-shrinkable sheet was heat-treated at shrinkage rates of 10%, 20% and 30%, and the appearance after heat shrinkage was examined. The results are shown in Table 2.

The sheet of C2 to C4 according to the present invention has a uniform appearance even when heat-shrinked at a shrinkage ratio of 20 to 30%, whereas the Al layer using an aluminum foil or a vapor deposition film as an Al layer. It was impossible to heat-shrink the sheets A4 and B1-B4 with a uniform appearance even with a shrinkage of 10%.

Effects of the Invention In the heat-shrinkable sheet of the present invention, both front and back surfaces of the metal thin film,
Since a heat-shrinkable film is provided through an adhesive layer that has a dry film elongation of 200% or more, even if it is shrunk to a high degree, it does not peel off the metal thin film and generate foil dust, which is stable for any application Can be used. Furthermore, the back-pasting process can be performed by a simple method such as simply using a solvent, and the appearance at the time of high shrinkage is a satin-like appearance in which the metal thin film shrinks uniformly according to the shrinkage of the heat-shrinkable film. It becomes calm and noble.

Claims (2)

[Claims] 1. A heat-shrinkable film provided on both front and back surfaces of a metal thin film via an adhesive layer, each of the adhesive layers having a dry film elongation of 200% or more, and the adhesive layer. Is a thickness of 5 μm or less, and the metal thin film is formed in a layer thinner than the adhesive layer. A heat-shrinkable sheet excellent in metallic luster used for a cap seal of a bottle and the like. 2. The heat-shrinkable films provided on the front and back surfaces of the metal thin film have different thicknesses, and one of the thicknesses is 80 to 15% of the thickness of the other. (1)
The heat-shrinkable film described.