JPS5839066B2 - Plastic film with thermal adhesive properties - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plastic film having thermal adhesive properties that can be used as a surface protection film and packaging material for decorative laminates mainly used as building materials, such as decorative steel sheets and plywood.

In recent years, decorative steel sheets and decorative plywood used as building materials are coated with adhesive on one side of a plastic film such as polyethylene to prevent damage to the painted surface during construction, processing, transportation, and storage. Temporarily attached adhesive plastic film or paper coated with adhesive on one side is used.

The first characteristic desired for a temporary adhesive film for decorative laminates is that it has the adhesive strength necessary to protect the surface of the decorative laminate during storage, transportation, processing, construction, etc. If the body film is unnecessary, it can be easily peeled off from the adherend.

That is, the adhesive force between the temporary adherent film and the adherend is 150 to 4
00g720%, the adhesive strength does not change during storage.

The second is that no residue remains on the surface of the adherend when it is peeled off from the temporary adherend.

However, with conventional adhesive plastic films and adhesive papers, the adhesive strength of the adhesive is highly temperature dependent, so the adhesive strength of the temporary bond changes significantly over time, and if stored at a low temperature of 5 degrees Celsius or less for a long period of time, the temporary bond will deteriorate. The adhesion force of the temporary adherend becomes weak and it may peel off from the adherend, and if stored for a long time at high temperatures of 30°C or higher, the adhesive force of the temporary adherend increases significantly. There are drawbacks that make it difficult.

Further, when the adhesive plastic or adhesive paper is peeled off, a part of the adhesive layer remains on the surface of the adherend, which has the disadvantage of impairing the appearance of the adherend.

In addition, as a surface protection sheet for metal plates, etc., 20 to 10
One side of a flexible plastic support sheet with a linear expansion coefficient of 2 x 10" or less at 0°C has a vinyl acetate content of 5 to 5
Utility Model Publication No. 47-13902 discloses a heat-adhesive sheet obtained by providing a heat-activated adhesive layer mainly made of ethylene-vinyl acetate copolymer with a weight ratio of 0.0 weight, and further subjecting the surface of the adhesive layer to a corona discharge treatment. It is known from the publication no.

However, in the surface protection plastic sheet described in Japanese Utility Model Publication No. 47-13902, when the ethylene-vinyl acetate content of the thermal adhesive layer is less than 10%, the thermal adhesion to decorative steel sheets, decorative plywood, etc. is poor; If the protective sheet is left to cool after thermal adhesion to a decorative board, etc., the protective sheet will naturally separate from the end of the adherend.

A protective sheet such as a decorative board with a thermal adhesive layer of ethylene-vinyl acetate copolymer has a practically sufficient adhesive strength (approximately 150 to 4
009/20r I
It is necessary to perform the corona discharge treatment so that the diameter is greater than □□□.

However, the ethylene-vinyl acetate copolymer film on a heavy board with a vinyl acetate content of 18% has weak adhesion or stickiness even at room temperature, and the wetting tension on its surface is 37 dynes/cm or more. When corona discharge treatment is applied, the adhesion at room temperature increases significantly, resulting in a blocking phenomenon when wound in layers.

That is, when the sheet is rolled, it becomes one piece, making it difficult to unwind it, and the work of laminating it onto a decorative board or the like is seriously hindered, making it impossible to put it to practical use.

Furthermore, when using a board with a vinyl acetate content of 18 weight and a wetting tension of 37 dynes/wound or more, the adhesive strength changes significantly over time, especially at high temperatures, as with the temporary adherents described above. The disadvantage is that it is very difficult to remove from the body.

In order to eliminate such drawbacks, the present inventors conducted intensive research on the thermal adhesion of various thermoplastic resin films to decorative laminates, and found that the ethyl acrylate content was 5 to 1.
The surface of a film made of ethylene-ethyl acrylate copolymer (hereinafter referred to as EEA copolymer) of 8% by weight is subjected to corona discharge treatment so that the wetting tension becomes 37 dynes/□□□ or more. It has appropriate thermal adhesion to the painted surface, and there is little change in adhesive strength over time. Moreover, the EEA copolymer film has a wetting tension of 37 dynes/α or higher even when subjected to corona discharge treatment. It has been found that it has no adhesive properties at room temperature, does not cause any blocking phenomenon even when wound in layers, and has good handling and workability.

In addition, E with an ethyl acrylate content of 5 to 18% by weight
The surface of the EA copolymer film subjected to corona discharge treatment has zero thermal adhesion not only to the painted surface of decorative laminates but also to base materials such as paper, plastic plates, and glass plates. I discovered that.

The present invention is based on such findings, and includes an EEA copolymer having an ether acrylate content of 5 to 18% by weight on one side of a support film made of polyolefin resin and having a thickness of 0.02 to 0.1%. Thickness from rj 0.003 to 0.0
3% thermal adhesive layer is laminated, and the surface thereof is subjected to corona discharge treatment so that the wet tension becomes 37 dynes/piece or more. This is a plastic film with thermal adhesive properties that can be used as any packaging material.

When the plastic film according to the present invention is used as a protective film, the coating surface of decorative steel plate fL, decorative plywood, etc. that has been preheated to 40 to 80° C.
By thermally bonding at a temperature of 150°C, the adhesive strength is 150°C, which is desired as a surface protection material for decorative steel sheets and decorative plywood.
~4009720%, and it is possible to obtain adhesive strength with little change over time.

However, E with an ethyl acrylate content of 5% by weight or less
EA copolymer films have poor adhesion, and EEA copolymer films on 18-weight plates with an ethyl acrylate content show significant changes in adhesion over time, that is, when stored for long periods at high temperatures of 30°C or higher Adhesion strength increases significantly,
1. is preferred because it is extremely difficult to peel off from the adherend.・.

Furthermore, if the wet tension of the EEA copolymer film is less than 37 dynes/socket, the adhesion to decorative boards etc. is poor and it is difficult to obtain a practically sufficient adhesion force.

When using the plastic film according to the present invention for skin packaging, the film is uniformly heated and melted,
Vacuum suction is applied from below the mount to bring the film into close contact with the object to be packaged, and the film is also thermally bonded to the mount, thereby making it possible to fix the object to the mount.

The polyolefin resin support film used in the present invention may be made of polyethylene, polypropylene, ethylene-propylene copolymer, ionomer resin, etc. alone or with additives such as slip agents and antistatic agents added as necessary; There are films processed by mixing these resins.

Furthermore, the most economical method for laminating the polyolefin resin support film and the EEA copolymer film is to use a known coextrusion method.

In addition, the thickness of the film is determined based on handling efficiency and economic considerations.
The thickness of the polyolefin resin support film is 0.03~
0.1%, EE A copolymer film thickness is 0.0
03 to 0.03r'yn is suitable.

The effects of the product of the present invention as a protective film for decorative laminates will be shown in Examples below.

Examples 1 to 8 Modern Machinery (using a coextrusion device manufactured by Kikisha, that is, extruder 1 (65%φ extruder) extruded polyolefin resin at an extrusion temperature of 220 to 280°C, extruder 2 (50%
%φ extruder) to extrude the EEA copolymer at a temperature of 220~
Extrude at 280℃ and connect both with a special connector at 22℃.
Combine and combine at a temperature of 0 to 280°C, 220 to 28
Polyolefin resin and EE are produced from a 1'-die (600rynφ, single manifold die) heated to 0°C.
Coextruded as a melt bilayer film with A copolymer, 30
0nXnφX 700'/, 12 and 200'XφX70
A two-layer film of any thickness is processed using a film take-up device (manufactured by Osaka Seiki Kogyo Co., Ltd.) consisting of two cooling rolls with 0 $ A corona discharge treatment was performed using a 12KVA high frequency corona discharge treatment apparatus to prepare a surface protection film for a decorative board.

Next, a surface protection film was placed on the painted surface of a 1% thick steel sheet coated with acrylic paint, which had been preheated to 60°C, so that the surface of the EEA copolymer film that had been treated with corona discharge was in contact, and the temperature was increased. 120°C1 pressure 4Ky/C
rrl was heated and thermally bonded using a pressure roll, and the adhesive force between the decorative steel plate and the surface protection film was measured, and the results shown in the table were obtained.

Comparative Examples 1 to 4 Laminated to a decorative steel plate in the same manner as in the example except that a KEA copolymer film having different wetting tension and ethyl acrylate content from the EEA copolymer film used in the example was used. Processed.

The adhesive strength at that time is shown in the table.

Comparative Example 5 DQDJ-18 instead of EEA copolymer used in Example
A surface protection film was processed and laminated with a decorative steel sheet in the same manner as in the example except that Nippon Unicar (Ethylene-vinyl acetate copolymer made by Kiki: vinyl acetate content: 10 weight) was used. .

The adhesive strength at that time is shown in the table. Comparative Example 6 DQD J-3 instead of DQDJ-1830 in Comparative Example 5
A surface protection film was processed and laminated with a decorative steel sheet in the same manner as in the example except that 868 (Ethylene-vinyl acetate copolymer manufactured by Nippon Unicar Co., Ltd.: vinyl acetate content 20% by weight) was used. .

The adhesive strength at that time is shown in the table. Comparative Example 7 Lamination processing with a decorative steel plate was carried out in the same manner as in the example except that commercially available adhesive paper was used instead of the surface protection film used in the example.

The adhesive strength at that time is shown in the table.

As is clear from the table, the protective film according to the present invention has the following properties:
Adhesion strength 15 desired as a protective film for decorative steel sheets
0 to 400 g/20rIXn, and the adhesive strength should not change much even if stored at high temperatures for a long period of time.

Furthermore, when the decorative steel sheet was peeled off from the film, no foreign matter remained and the surface was very flat.

On the other hand, EEA copolymer films with a wetting tension of 37 dynes/dyne or less have weak adhesion to decorative steel plates, and naturally separate from the end of the adherend during storage.

In addition, EE with an ethyl acrylate content of 5% by weight or less
Copolymer A film also has weak adhesion to decorative steel sheets.
Nature has gone away.

On a plate with an ethyl acrylate content of 18 weight, the adhesive strength increased significantly when stored at high temperature for a long period of time, and when the film was peeled off from the decorative steel plate, the film broke and peeling was extremely difficult.

When an ethylene-vinyl acetate copolymer is used instead of an EEA copolymer, the adhesive force is weak when the vinyl acetate content is 10 deuterons, and it naturally peels off, whereas when the vinyl acetate content is 20 deuterons, it does not adhere well at high temperatures. When stored for a long period of time, the adhesive strength increased significantly, and when the film was peeled off from the decorative steel plate, the film broke and was extremely difficult to peel off.

In addition, when adhesive paper is used instead of the product of the present invention and stored at high temperature for a long period of time, the adhesive strength increases significantly, and the paper layers occasionally separate, causing some of the adhesive and paper to separate. remained on the decorative steel plate, resulting in poor appearance.

The protective film according to the present invention has the following advantages compared to conventional products.

1) The price is low.

2) There is little change in the adhesive strength of the protective film over time.

3) When the film is peeled off from the adherend, residues such as adhesives should remain on the surface of the adherend.

4) Excellent workability in laminating to adherends (the film has no adhesive properties at room temperature and can be laminated to adherends using a simple heating device).

5) The transparency of the film laminated to the adherend is very good, making it easy to select the adherend.

Claims (1)

[Claims] 1 Made of polyolefin resin, thickness 0.02-0.
A thermal adhesive layer with a thickness of 0.003 to 0.03% made of an ethylene-ethyl acrylate copolymer having an ethyl acrylate content of 5 to 18% by weight is laminated on one side of a 1 nyn support film, and the surface is wetted to create a tension. 37 dynes/crrr
A plastic film with thermal adhesive properties characterized by being subjected to corona discharge treatment to achieve the above properties.