JPH10110145A - Surface protection film for metal plate processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject film not peeling off and not transferring its surface form to a metal surface in metal plate processing, by specifying its residual stress when deformed at 100%. SOLUTION: This surface protecting film bears an adhesive layer on its one side, and has a residual stress of <=0.4kgf/cm<4> when deformed at 100% and is <=0.2μm in center line average roughness of the surface of at least the side having the adhesive layer. It is preferable that the film has a tensile elongation of >=100% and tensile modulus of 20 to 60kgf/mm<2> , and is a laminated film in at least three layers with the outermost layer consisting of a crystalline polyolefin layer, and the inner layer thereof a noncrystalline polyolefin layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a surface protection film for processing a metal plate.

[0002]

2. Description of the Related Art Conventionally, when processing or transporting a metal plate such as a stainless steel plate, an aluminum plate, a steel plate, etc., a surface protection film is temporarily attached so that the surface of the metal plate is not damaged. The surface of the metal plate is protected. As such a surface protection film for a metal plate, for example, a film formed by mixing polyethylene and polypropylene and provided with an adhesive layer on one surface (Japanese Patent Publication No. 59-59)
A film obtained by mixing two or more of polyethylene, polypropylene and ethylene-propylene copolymer at a specific mixing ratio and having an adhesive layer on one surface (see Japanese Patent Publication No. No. 14667) is known.

[0003]

However, when a metal plate is subjected to processing such as deep drawing or bending, the surface protective film cannot follow the plastic deformation of the metal plate, and a part of the film is peeled or torn. Or something. Especially,
In the manufacture of a deep bottom that cannot be manufactured by a single deep drawing such as a sink part (sink tank) of a sink, it is necessary to perform redrawing after the first deep drawing. In this case, it is necessary to perform the first deep drawing. If the surface protective film is peeled or torn, a dent is formed on the surface of the metal plate in the next re-drawing, resulting in a problem of impairing commercial value.

On the other hand, if the adhesive strength of the surface protective film is increased in the above, peeling and tearing of the surface protective film can be eliminated, but there is a problem that the work of peeling the surface protective film becomes difficult. Therefore, it is necessary to eliminate peeling and tearing of the surface protection film without increasing the adhesive strength.

Further, when deep drawing is performed on a metal plate as in the case of a sink portion of a sink, radial wrinkles are easily generated in the sink portion. Therefore, plastic deformation around the sink portion is generally called a wrinkle holder. It is necessary to apply a load from above to the parts that do not. However, when the sink (sink tank) and the stage (cooking table) are integrated like a recent stainless steel sink, it is necessary to apply a load to the stage from above. If the surface is rough, the surface shape of the film is transferred to the stage portion, which causes a problem that the commercial value is impaired similarly to the dents.

An object of the present invention is to provide a surface protection film for processing a metal plate which does not peel off during processing of the metal plate and does not transfer the surface shape to the surface of the metal plate.

[0007]

The surface protection film for processing a metal plate of the present invention has the following features. (1) The film has an adhesive layer on one side and the amount of deformation is 1
The residual stress in the case of being 00% is 0.4 kgf / cm ² or less, and the center line average roughness of at least the surface having the adhesive layer of the film is 0.2 μm or less. Surface protection film for metal plate processing.

(2) The tensile elongation is 100% or more,
Tensile modulus of elasticity of 20kgf / mm ² ~60kgf / mm ²
The surface protective film for processing a metal plate according to the above (1).

(3) The film is formed by laminating at least three layers, wherein the outermost layer is a layer of crystalline polyolefin, and the inner layer is a layer of amorphous polyolefin. The surface protective film for processing a metal plate according to 1).

[0010]

The surface protective film for processing a metal sheet of the present invention has a residual stress of 0.4 kgf / cm ² when the deformation is 100%.
Because of the following, it is possible to prevent the film from being partially peeled off due to residual stress and to be lifted or torn.
Therefore, when redrawing is performed after deep drawing, which has conventionally been a problem, it is possible to suppress the formation of dents on the surface of the metal plate during redrawing. Furthermore, peeling of the film edge when the metal plate is left unattended can be suppressed.
Moreover, since peeling and tearing of the film can be suppressed without increasing the adhesive strength of the film, the peeling operation does not become difficult.

Further, since the center line average roughness of the surface of the film having at least the pressure-sensitive adhesive layer is 0.2 μm or less, the surface shape of the film may be transferred to the surface of the metal plate during the processing of the metal plate. It can be suppressed, and even if it is transferred, it cannot be confirmed visually or by a surface roughness meter.

Further, since the surface protection film for processing a metal sheet of the present invention has a tensile elongation of 100% or more, even when the amount of deformation of the metal is large, such as in deep drawing, it is almost equal to the deformation of the metal. Can be transformed into Further, the surface protective film for processing a metal plate of the present invention has a tensile modulus of 20 kgf / mm ² or more.
Since the pressure is 60 kgf / mm ² , there is no possibility that the metal sheet is unnecessarily stretched at the time of peeling or cannot be deformed following the plastic deformation of the metal plate.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The metal sheet surface protection film of the present invention is a film
An adhesive layer is provided on one side, and the amount of deformation
Residual stress generated at 100% is 0.4 kgf / c
m^TwoThe following, and at least the adhesion of the film
The center line average roughness of the surface having the agent layer is 0.2 μm or less
It is characterized by being below. Further, the tensile elongation is 10
0% or more, tensile modulus of 20 kgf / mm^Two~ 60kg
f / mm ^TwoIt is more preferable that the metal plate
It becomes a surface protection film for construction.

The film may be any one as long as it becomes a base material of the surface protection film for processing a metal plate having the above characteristics. Even if the film is made of a kind of material,
It may be composed of a material in which two or more kinds are mixed, and may have a single-layer structure composed of only one layer or a multilayer structure composed of two or more layers.

When the film has a single-layer structure, it is preferable to use a mixture of polypropylene and polyethylene as the film material. This is because a film made of a mixture of polypropylene and polyethylene has a sea-island structure and is phase-separated (polypropylene: sea, polyethylene: island), and a gap is generated between the sea-island phases to easily ease stress. In this case, the thickness of the film is from 20 μm to
It is preferably 200 μm.

In the case where the film has a multi-layer structure, at least three or more multi-layer structures in which the outermost layer is a layer of a crystalline polyolefin and the inner layer is a layer of an amorphous polyolefin. preferable. With such a multi-layer structure, the intermediate layer is provided with a layer of amorphous polyolefin in which no distortion remains even after plastic deformation,
Compared with a film made of only crystalline polyolefin having the same thickness, a portion where residual stress is generated is reduced, which is a preferable film.

Specifically, when a layer of a crystalline polyolefin is represented by (a) and a layer of an amorphous polyolefin is represented by (b), (a), (b), and (a) are laminated in this order. A layer structure, a five-layer structure in which layers (a), (b), (a), (b), and (a) are stacked in this order, are not particularly limited as long as they are three or more layers. In such a multilayer structure, the thickness of the amorphous polyolefin is preferably 10 μm to 180 μm, and the thickness of the crystalline polyolefin is preferably 10 μm to 20 μm. Further, the thickness of the entire film is preferably from 20 μm to 200 μm, particularly preferably from 30 μm to 70 μm, in the case of a three-layer structure.

Examples of the amorphous polyolefin include a copolymer of propylene and another α-olefin, atactic polypropylene and the like. As the atactic polypropylene, a by-product produced during the production of crystalline polypropylene may be used. Further, both a copolymer of propylene and another α-olefin and atactic polypropylene may be directly produced from propylene or the like as a raw material, and a slurry method may be used as a production method. Also, commercially available amorphous polyolefins may be used, and specific examples thereof include REXTAC (Rexene) of the United States.

As the crystalline polyolefin, polypropylene or the like which is generally commercially available for extrusion molding, injection molding, blow molding and the like may be used. Specifically, there is Showa Lomer FA432 manufactured by Showa Denko.

The residual stress generated in the surface protection film for processing a metal plate of the present invention refers to an elastic force generated in the film. That is, since the film is a kind of elastic body, when the metal plate to which the film is attached is plastically deformed, an elastic force is generated in the film to return to the original state, and this elastic force becomes residual stress. The residual stress may be 0.4 kgf / cm ² or less when the deformation is 100%, but may be 0.4 kgf / cm ² or less even when the deformation is less than 100%. In addition, the deformation amount here is 100%,
It means that the elongation of the film in any direction is 100%.

The residual stress was measured by measuring a tape-shaped test piece (width: 20 mm, length: 100 mm) with a distance of 50 m between chucks.
m and stretched at a rate of 300 mm / min until the deformation of the test piece reaches 100%, and then left for 5 minutes to measure the stress generated in the test piece.
In addition, when the deformation amount is 100%, the residual stress is 0.4 kg.
f / cm ² or less, the deformation amount is 1
A film which causes necking when the film is stretched at not more than 00% may be used. That is, a film having a tensile yield point of 100% or less may be used. Specifically, a film made of the above-described material may be used.

The base film must have a center line average roughness of at least 0.2 μm on at least the surface having the pressure-sensitive adhesive layer or on both surfaces. In addition, the measurement of the center line average roughness of the film surface is performed by
The measurement was performed at a measuring speed of 0.3 mm / sec, a measuring length of 5 mm, and a cut-off value of 0.8 mm using TURCOM 564A manufactured by Tokyo Seimitsu. In order to reduce the center line average roughness of the film surface to 0.2 μm or less, the film may be formed by using a three-layer T-die method or an inflation method. At this time, if the surface roughness exceeds 0.2 μm, a mirror-finished roll may be applied after extrusion as appropriate.

The tensile elongation of the surface protective film for processing a metal sheet of the present invention is preferably 100% or more. Therefore, even when the metal plate is subjected to a large deformation such as deep drawing, the film can be deformed to the same extent. In particular, in the production of a sink (sink tank) of a stainless steel sink by deep drawing, the amount of deformation of the stainless steel plate is 100% at the maximum, and even in this case, the film can be deformed to the same extent. The tensile elongation was measured by JI
SZ0237 (Adhesive tape, adhesive sheet test method)
The test is performed by stretching a tape-shaped test piece at a speed of 300 mm / min to break it, and measuring the elongation at that time. Further, by controlling the stretching ratio at the time of film formation, the tensile elongation of the film can be made 100% or more.

The metal sheet processing protective film of the present invention is preferably in the tensile modulus 20kgf / mm ² ~60kgf / mm ² a. By doing so, there is a problem that the film is unnecessarily stretched when peeled from the metal plate due to a small tensile modulus, and the peeling workability is reduced, and a deformation of the metal plate due to a large tensile modulus. Thus, it is possible to solve the problem that the deformation of the film cannot follow the film, causing the film to float. In addition, the measurement of the tensile elastic modulus is in accordance with JIS K7127 (tensile test method for plastic films and sheets), and a tape-like test piece (width 20 mm, thickness 0.05 mm) is gripped at a distance of 100 mm and a speed of 300 mm / min. Stretching is performed.

The method for producing the film is not particularly limited, but is a known production method such as the inflation method or the T method.
A die method or the like may be used, and may be determined according to the film material, production scale, and the like. If the film has a multilayer structure, it can be manufactured by a multilayer inflation method or a multilayer T-die method using a plurality of extruders and a die capable of stacking and extruding a plurality of materials with a uniform thickness. good.

As the pressure-sensitive adhesive layer, a pressure-sensitive adhesive generally used for a pressure-sensitive adhesive film may be used, and examples thereof include known acrylic-based pressure-sensitive adhesives and rubber-based pressure-sensitive adhesives. The pressure-sensitive adhesive layer has a thickness of 1 μm to 20 μm, and has an adhesive force of 50 gf / stainless steel plate (SUS304BA).
It is preferable to prepare so as to be 20 mm to 600 gf / 20 mm. In addition, the measurement of the adhesive strength is based on JIS Z 15
Perform according to 22.

[0027]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 [Preparation of Film] Atactic polypropylene produced as a by-product during the production of crystalline polypropylene was used as the amorphous polyolefin, and Showaomer FA432 (manufactured by Showa Denko) was used as the crystalline polyolefin. A three-layer film was prepared by laminating a crystalline polyolefin layer on both sides of a high-quality polyolefin layer by a multilayer T-die method. The temperature of the extruder at this time was set to 230 ° C. The thickness of the entire film was 70 μm (amorphous polyolefin layer 50 μm, crystalline polyolefin layer 10 μm).

[Preparation of pressure-sensitive adhesive layer] butyl acrylate 92
To 100 parts by weight of a copolymer consisting of 5 parts by weight of acrylonitrile and 3 parts by weight of acrylic acid, 3 parts by weight of hexamethylene isocyanate was added to obtain an acrylic pressure-sensitive adhesive. Next, the pressure-sensitive adhesive was applied to one surface of the film obtained above so as to have a dry thickness of 5 μm to obtain a surface protective film for processing a metal plate of the present invention.

Example 2 80 parts by weight of polypropylene (showaromer FA43)
2: Showa Denko) and 20 parts by weight of polyethylene (SHOLEX F141: Showa Denko) were mixed, and a film was formed to a thickness of 50 μm by a T-die method.
The temperature of the extruder was set at 230 ° C. next,
A pressure-sensitive adhesive layer was provided in the same manner as in Example 1 to obtain a surface protection film for processing a metal plate of the present invention.

[Measurement of Physical Properties of Metal Sheet Processing Surface Protective Film] The above conditions for residual stress, center line average roughness, tensile elongation and tensile elasticity of the metal sheet processing surface protective film obtained above were obtained. And are shown in Table 1.

[0032]

[Table 1]

[Evaluation of workability] The surface protection film (1360 mm in length and 925 mm in width) obtained above for metal sheet processing was pasted on a stainless steel plate (SUS304BA), and the sink part (520 mm in length and 830 mm in width) of a sink was actually used. , Depth 200 mm). The pressing load at this time was set to 600 t, and the size of the sink portion was set to the above size by two deep drawing operations. After processing, tearing of the film,
Floating and transfer of the surface shape of the film were confirmed, and the evaluation was evaluated as な け れ ば if no problem occurred in the product due to these, and evaluated as × if any problem occurred. Table 2 shows the results.

[Evaluation of peeling workability] After the above-mentioned processing was completed, the surface protective film for processing a metal plate was peeled from the stainless steel plate, and the peeling workability was evaluated. The evaluation of the peeling workability was carried out on two items: whether the film was torn at the time of peeling (tearability) and whether the film was unnecessarily stretched to make work difficult (workability). If the workability did not decrease, it was evaluated as ○, and if the peelability decreased, it was evaluated as ×. Table 2 shows the results.

[Comprehensive Judgment] The overall judgment was "O" if the film could be suitably used as a surface protective film for processing a metal sheet, and "X" if it could not be used.
Table 2 shows the results.

[0036]

[Table 2]

Comparative Example 1 A film was obtained by melting and extruding a low-density polyethylene, and the adhesive layer had a dry thickness of 7 μm.
A surface protection film for processing a metal plate was prepared and evaluated in the same manner as in Example 1 except for the following. Tables 1 and 2 show the results.

Comparative Example 2 A film was obtained by melting and extruding a mixture of 80 parts by weight of granular polypropylene and 20 parts by weight of granular polyethylene, and the adhesive layer had a dry thickness of 7 μm. A surface protection film for processing a metal plate was prepared and evaluated in the same manner as in Example 1 except for the following. Tables 1 and 2
Shows the results.

[Evaluation] The surface protective film for processing a metal plate prepared in Example 1 has physical properties required in the present invention as can be seen from Table 1, and as shown in Table 2, Good results were also obtained for workability and peeling workability.

[0040]

As described above, since the surface protection film for processing a metal plate of the present invention has a small residual stress when deformed, the film peels or tears during the processing of the metal plate without increasing the adhesive strength of the pressure-sensitive adhesive layer. Nothing. Further, since the adhesive strength does not need to be increased, the peeling workability does not decrease. Further, since the transfer of the film surface shape to the metal plate is suppressed, the occurrence of defective products due to the transfer is suppressed.

Claims (3)

[Claims] 1. A film having an adhesive layer on one side and a residual stress of 0.4 kgf / c when the amount of deformation is 100%.
is intended to be m ² or less, the metal plate working surface protective film, wherein the center line average roughness of the surface of the side is 0.2μm or less having at least a pressure-sensitive adhesive layer of the film. Wherein the tensile elongation is 100% or more, a tensile modulus of 20kgf / mm ² ~60kgf / mm ² a metal plate working surface protective film according to claim 1, wherein. 3. The film according to claim 1, wherein the film is formed by laminating at least three layers, wherein the outermost layer is a layer of crystalline polyolefin, and the inner layer is a layer of amorphous polyolefin. The surface protection film for processing a metal plate according to the above.