JPH06220412A - Pressure-sensitive adhesive sheet for surface protection - Google Patents

Abstract

PURPOSE:To obtain the subject sheet which hardly suffers a phenomenon such as necking when stretched and which, even when a metal plate having the sheet stuck to the surface is subjected to, e.g. drawing, can quickly follow the deformation of the metal plate so that it is hardly broken and scarcely mars the surface of the metal plate. CONSTITUTION:This adhesive sheet is made by forming a pressure-sensitive adhesive layer on one side of a film base. The film base contains a polypropylene and at least 40wt.% olefin elastomer consisting mainly of ethylene and propylene and has a modulus in tension of 3,000-7,000kg/cm<2> with no yield point and a recovery from deformation under a tensile load of at most 70%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-protective pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer provided on one surface of a film substrate, and particularly to protect the surface of a metal plate or a coated steel plate and prevent scratches during drawing. The present invention relates to a surface protective pressure sensitive adhesive sheet.

[0002]

2. Description of the Related Art Conventionally, in order to protect the surface of a metal plate such as a stainless plate, an aluminum plate or a copper plate or a coated steel plate (hereinafter abbreviated as a metal plate) or when drawing these metal plates. In order to prevent the surface from being scratched, a surface-protective pressure-sensitive adhesive sheet for protecting the surface of a metal plate or the like has been generally used. As the surface protective pressure-sensitive adhesive sheet, conventionally, one in which an acrylic or rubber pressure-sensitive adhesive layer is provided on one surface of a film base material made of a soft vinyl chloride film is widely used. Since the soft vinyl chloride film does not have a yield point during tensile deformation, necking is unlikely to occur due to the tensile force applied when drawing is applied, and it stretches uniformly during drawing.
Therefore, it is preferably used.

On the other hand, in recent years, vinyl chloride films have problems such as final collection problems and adverse effects on the environment upon incineration. Therefore, soft vinyl chloride films have been replaced by olefin-based materials. A conversion is required.

In view of this, Japanese Patent Laid-Open No. 3-14885 proposes a surface protective pressure-sensitive adhesive film for drawing, which comprises a base film made of a polyolefin film made of a propylene-ethylene copolymer resin. Further, JP-A-4-106175 proposes a surface protective pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer is provided on one surface of a base film formed by mixing polypropylene, polyethylene, and an ethylene-propylene copolymer. There is.

[0005]

However, in the surface protective pressure-sensitive adhesive sheet using the above-mentioned conventional polyolefin film base material, necking occurs when a tensile force is applied. Therefore, when the film is attached to a metal plate or the like and subjected to a drawing process, the film may not be uniformly stretched and a constriction may occur. As a result, on the deformed metal plate,
There is a problem that the pattern of the constricted portion is attached, or that the thinnest portion of the film base material is torn and the metal plate is scratched.

An object of the present invention is to provide a surface-protective pressure-sensitive adhesive sheet which is used by being attached to a metal plate or the like and protects the surface of the metal plate or the like during drawing, and which uses a polyolefin film base material. In spite of the above, it is an object of the present invention to provide a surface-protective pressure-sensitive adhesive sheet which is unlikely to cause necking and therefore can reliably protect metal plates and the like.

[0007]

The surface protective pressure-sensitive adhesive sheet of the present invention has been made to achieve the above-mentioned object and has the following constitution.

That is, the surface protective pressure-sensitive adhesive sheet of the present invention is a surface protective pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed on one surface of a film substrate, wherein the film substrate is made of polypropylene and mainly ethylene-propylene. An olefin-based elastomer is contained, the content of the olefin-based elastomer is 40% by weight or more, and the tensile strength is 3000 kg / cm ^{2 to} 7000 kg / cm.
² , the yield recovery point is 7 and the deformation recovery rate after tensile deformation is 7
It is characterized by comprising a film having a content of 0% or less.

As described above, the film base material used in the present invention contains polypropylene and the above-mentioned olefin elastomer, and such a film base material is polypropylene and an ethylene-propylene copolymer. And the ethylene-propylene copolymer ratio is 4
It can be obtained by mixing so as to be 0% by weight or more, but preferably, it can be obtained by polymerizing ethylene and propylene monomers in the presence of a predetermined polypropylene, that is, by a so-called reactor blending method. The specific method of this reactor blend,
And the structure and physical properties of the obtained reactor blend,
It is well known in the art, for example, "Polymer Jou".
rnal, Vol. 17, No. 1, pp. 37-55 (1985) "and JP-A-3-205439.

Further, the olefin elastomer mainly composed of ethylene-propylene may be a copolymer of a third component such as butene, if necessary. As an example of the polyolefin-based material of the above reactor blend, Catalloy KS-01 manufactured by Highmont Co., Ltd.
0, the same KS-020, the same KS-030 and the like.

The content ratio of the above olefinic elastomer mainly composed of ethylene-propylene is 4 as described above.
It should be 0% by weight or more. This is important for controlling the physical properties such as the elastic modulus of the film, the strength, and the behavior during stretching. When the content is less than 40% by weight, an adhesive layer is formed on one side. When it is provided to form a surface protective pressure-sensitive adhesive sheet, drawability is not sufficient, and the balance of sticking property, peeling property and the like is deteriorated. Therefore, the content ratio of the olefin elastomer needs to be 40% by weight or more, and more preferably 50% by weight or more, a surface protective pressure-sensitive adhesive sheet having a better balance of physical properties can be obtained.

The content ratio of the olefin elastomer may be 40% by weight or more, but the upper limit is preferably about 70% by weight. 70
If it exceeds 5% by weight, it becomes too soft and the drawability and the like may deteriorate.

The yield point is described in "Mechanical properties of polymers and composites" (LE NIELSEN, translated by Shigeharu Onoki, pages 183 to 188, Kagaku Dojin). As described above, when a sample is stretched, a constriction occurs at a certain limited point of the sample film, and a phenomenon in which the constricted portion grows long with stretching is called necking. The cross section of this neck is
It is much smaller than the cross section of the rest of the film.
When the constricted portion occurs when the surface protection pressure-sensitive adhesive sheet is attached to a metal plate or the like and deep drawing is performed, a difference in thickness partially occurs in the surface protection pressure-sensitive adhesive sheet, and the surface protection pressure-sensitive adhesive sheet is cut or metal. It is considered that scratches such as streaks occur on the surface of the plate or the like.

The elastic modulus of the film base material used in the surface protective pressure-sensitive adhesive sheet of the present invention has a great influence on the stickability to a metal plate or the like, the extensibility during drawing, and the peeling property. Therefore, in the present invention, the tensile modulus is 300
It is ^{0kg / cm 2 ~7000kg / cm 2} . Thirty
If it is less than 00 kg / cm ^2, it will be too soft and the surface protective adhesive sheet will stretch during sticking, or the surface protective adhesive sheet will tear when sticking to a metal plate etc. and then cut when peeled off. There is a problem of doing. On the other hand, if it is greater than 7000 kg / cm ² ,
There is a possibility that the deformation of the metal plate or the like cannot be followed during the drawing process. The elastic modulus is a value measured according to JISK 7127.

The deformation recovery rate after tensile deformation of the film base material used in the present invention is such that the surface protective pressure sensitive adhesive sheet floats over time when a metal plate or the like to which the surface protective pressure sensitive adhesive sheet is attached is drawn. Related to the coming phenomenon. That is, when the deformation recovery rate is 70% or less, such floating is unlikely to occur, and more preferably 50% or less. If the deformation recovery rate exceeds 70%, a floating portion of the surface protective adhesive sheet may overlap with a peripheral surface protective adhesive sheet portion during drawing, and a scratch such as a dent may occur on the metal plate. Even if the deformation recovery rate is 70% or less, if the tensile elastic modulus exceeds 7000 kg / cm ² , the residual stress is large and the above floating occurs.

In the tensile test of the film, the above-mentioned deformation recovery rate means the elongation of 100% at a temperature of 23 ° C., the load is released after 5 minutes, and the length of the film after leaving for 5 minutes after opening is L _5min. Then, the deformation recovery rate = (2L ₀ −L
_{5 min} ) / L ₀ . However, L ₀ is
The length of the film in the initial state, that is, before stretching is shown.

In the surface protective pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive layer is formed on one surface of the above film substrate. As the pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer, a generally used pressure-sensitive adhesive can be appropriately used, and for example, an acrylic pressure-sensitive adhesive or a rubber-based pressure-sensitive adhesive can be used.

The pressure-sensitive adhesive is applied to the film substrate by applying a pressure-sensitive adhesive solution on one side of the film substrate and drying it, or by the pressure-sensitive adhesive and the above-mentioned olefinic system consisting of polypropylene and mainly ethylene-propylene. Any method such as a method of co-extruding a film base material component containing an elastomer to prepare a two-layer type surface protection adhesive sheet of base material / adhesive layer can be adopted. It is suitable that the thickness of the pressure-sensitive adhesive layer is usually about 3 to 20 μm, while the thickness of the film substrate is 30 to 120 μm.
It is appropriate to set the degree.

[0019]

In the surface protective pressure-sensitive adhesive sheet of the present invention, as a film substrate on which the pressure-sensitive adhesive layer is formed on one side, polypropylene and the olefin-based estomer mainly consisting of ethylene-propylene are contained as described above, Since the content of the elastomer is 40% by weight or more and it has the above-mentioned specific tensile elastic modulus, tensile property and deformation recovery rate, it is an olefin film substrate, but is drawn after being attached to a metal plate or the like. Even if it is applied, a surface-protective pressure-sensitive adhesive sheet can be obtained which can quickly follow the deformation of the metal plate or the like and is less likely to cause an undesired phenomenon such as necking.

[0020]

EXAMPLES The present invention will be described in more detail by describing examples below. Example 1 A base material containing 55% by weight of an olefinic elastomer composed of ethylene-propylene and 45% by weight of polypropylene (manufactured by Highmont, trade name; Catalloy KS-
031) and a thickness of 50 μm by an inflation method.
The film base material of m was produced. The tensile elastic modulus of the film base material was 3900 kg / cm ² , and the film base material did not show a yield point (does not cause necking) in the tensile test, and showed uniform elongation behavior. The deformation recovery rate (2L ₀ −L _5min ) / L ₀ of the film substrate was 47%.

A corona discharge treatment is applied to one surface of the film base material, an acrylic adhesive is applied to the treated surface so as to have a solid content of 5 μm, and dried at 100 ° C. for 5 minutes to give a surface protective adhesive. Got the sheet.

[0022]Example 2 Olefin-based elastomer consisting of ethylene-propylene
-Containing 55% by weight of polypropylene and 45% by weight of polypropylene
Base material (manufactured by Highmont, trade name; Catalloy KS-
011) and a thickness of 40 μm by an inflation method.
The film base material of m was produced. Tension of the film substrate
Elastic modulus is 5800 kg / cm²And the tensile test
However, the film substrate does not show a yield point (causing necking).
However, it showed a uniform elongation behavior. Also this fill
Deformation recovery rate of base material (2L₀-L _5min) / L₀Is 40%
Met. Next, using the above film substrate,
Similarly, a surface protective pressure-sensitive adhesive sheet was obtained.

Example 3 A base material containing 55% by weight of an olefinic elastomer composed of ethylene-propylene and 45% by weight of polypropylene (trade name; Catalloy KS-, manufactured by Highmont Co., Ltd.)
021), SEBS (styrene-based triblock copolymer, manufactured by Asahi Kasei Kogyo Co., Ltd., trade name; Tuftec 1052) as an adhesive, and tackifying resin (Arakawa Chemical Co., Ltd., trade name: Alcon P-125) in a weight ratio of 100. A mixture of a mixture of / 30 was extruded in a two-layer coextrusion T-die with a thickness of a substrate layer of 60 μm and an adhesive layer of 7 μm to obtain a surface protective adhesive sheet. 60μ thickness consisting only of base material
The film characteristic of m is that the elastic modulus is 3700 kg / cm ² ,
The deformation recovery rate (2L ₀ −L _5min ) / L ₀ was 50%. Further, a film made of only the base material at the time of the tensile test does not show a yield point (does not cause necking),
It showed a homogeneous elongation behavior.

Comparative Example 1 A film base material was obtained in the same manner as in Example 1 except that a base material containing 15% by weight of an olefin elastomer composed of ethylene-propylene and 85% by weight of polypropylene was used. A protective pressure sensitive adhesive sheet was prepared. During the tensile test of the film substrate, the film substrate showed a yield point and caused necking.

Comparative Example 2 A base material containing 60% by weight of an olefinic elastomer of ethylene-propylene and 40% by weight of polypropylene (trade name; Catalloy KS-, manufactured by Highmont Co., Ltd.).
063) was used, and in the same manner as in Example 1, a film substrate was obtained and a surface-protective pressure-sensitive adhesive sheet was produced.

The tensile elastic modulus of the film base material is 950.
a kg / cm ^2, (without causing necking) the film substrate showed no yield point when the tensile test showed a homogeneous elongation behavior. Further, the deformation recovery rate (2L ₀ −L _5min ) / L ₀ of this film substrate was 50%.

Comparative Example 3 The procedure of Example 1 was repeated except that a base material containing 80% by weight of an olefinic elastomer composed of ethylene-propylene and 20% by weight of polypropylene was used.
A film base material was obtained and a surface protective pressure-sensitive adhesive sheet was produced.

The tensile elastic modulus of the film base material is 750.
kg / cm ² , the film substrate showed no yield point (no necking) during the tensile test, and showed homogeneous elongation behavior. The deformation recovery rate (2L ₀ −L _5min ) / L ₀ of this film substrate was 90%.

Each of the surface protective pressure-sensitive adhesive sheets of Examples 1 to 3 and Comparative Examples 1 to 3 prepared as described above was cut to a length of 150 m.
m × width 150 mm × thickness 0.5 mm stainless steel plate (S
It was attached to a US304BA plate) from the pressure-sensitive adhesive layer side and subjected to a drawing process. In this drawing, as shown in FIG. 1, the stainless steel plate is 50 mm deep and has a bottom diameter of 85 mm.
Was performed by drawing so as to form the cylindrical portion 1. After the drawing process, the surface protective pressure-sensitive adhesive sheet was peeled off and the surface condition of the stainless steel plate was observed. The results are shown in Table 1 below along with the details of Examples 1 to 3 and Comparative Examples 1 to 3.

[0030]

[Table 1]

As is clear from Table 1, in the surface protective pressure-sensitive adhesive sheets of Comparative Examples 1 and 2, breakage occurred when the surface protective pressure-sensitive adhesive sheet was peeled off after drawing, and in Comparative Example 1, the surface of the stainless steel plate was scratched. Had occurred. Further, in the surface protective pressure-sensitive adhesive sheet of Comparative Example 3, a floating portion was generated on the surface protective pressure-sensitive adhesive sheet during the drawing process, and moreover, the surface of the metal plate after the drawing process was scratched. On the other hand, in the surface protective pressure-sensitive adhesive sheets of Examples 1 to 3, the sheet did not float during the drawing process, and the surface of the metal plate was not scratched after the drawing process.

[0032]

According to the present invention, the film base material of the surface protective pressure-sensitive adhesive sheet is composed of polypropylene and an olefin elastomer mainly composed of ethylene-propylene, and the content of the olefin elastomer is 40% by weight or more. In addition, since the tensile elastic modulus and the deformation recovery rate after tensile deformation are within the above specific range, when used as a surface protection adhesive sheet for metal plates or coated steel plates, even if deep drawing is performed. In addition, it is possible to quickly follow the deformation of the metal plate or the coated steel plate, and the surface of the metal plate or the coated steel plate is not damaged.

Therefore, it is possible to provide an excellent surface-protective pressure-sensitive adhesive sheet which replaces the conventional surface-protective pressure-sensitive adhesive sheet using a film base material made of a soft vinyl chloride film. Moreover, since the surface-protective pressure-sensitive adhesive sheet of the present invention contains polypropylene and the above-mentioned olefin-based elastomer as main components, problems of recovery and environmental pollution at the time of incineration are unlikely to occur.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a drawn sample performed when evaluating surface protective pressure-sensitive adhesive sheets of Examples and Comparative Examples.

Claims (1)

[Claims] 1. A pressure-sensitive adhesive layer is formed on one surface of a film substrate.
The surface protective pressure-sensitive adhesive sheet comprising
From polypropylene and mainly ethylene-propylene
And an olefin-based elastomer containing
The content of the tin-based elastomer is 40% by weight or more,
And the tensile strength is 3000kg / cm ²~ 7000kg
/ Cm²In, it does not have a yield point, and it recovers deformation after tensile deformation.
Characterized by comprising a film having a ratio of 70% or less
Surface protective adhesive sheet.