JPH0726213A - Surface protective film - Google Patents

Abstract

PURPOSE:To obtain a surface protective film with suitable initial adhesive properties by coextruding a substrate resin with a self-adhesive compsn. comprising a specific block copolymer, a tackifying resin, and an ethylene-butene copolymer in a specified wt. ratio. CONSTITUTION:100 pts.wt. block copolymer of an A-B-A type (wherein A is a styrene polymer block; and B is a butadiene polymer block, an isoprene polymer block, or an olefin polymer block formed by hydrogenating a butadiene or isoprene polymer block), 10-200 pts.wt. tackifying resin, and 30-300 pts.wt. ethylene-butene copolymer are compounded to give a self-adhesive compsn., which is coextruded with a polyolefinic resin to give the objective surface protective film comprising a polyolefinic resin substrate film and the self-adhesive compsn. layer formed on one side of the substrate film. The compsn. may further contain an antioxidant, an ultraviolet absorber, etc., if necessary.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a synthetic resin plate, a metal plate,
The present invention relates to a surface protection film that protects the surface of a decorative plywood, coated coated steel plate, various name plates, etc.

[0002]

2. Description of the Related Art Conventionally, a surface protective film has been attached to the surface of an adherend such as a metal plate such as a stainless steel plate, an aluminum plate or a coated steel plate or a plywood, and is used for transporting, storing or processing the adherend. It is used to prevent the body surface from being contaminated or scratched.

Therefore, the surface protective film does not adhere to the adherend to be peeled off during transportation, storage or processing of a metal plate or plywood, and can be easily peeled off during use. It is preferable that the body has no adhesive residue and does not contaminate the adherend.

However, when the adhesive strength of the surface protective film becomes weak, the surface protective film spontaneously peels off from the adherend during transportation or storage, so that the peeling speed is generally 50 mm / 25 m at 300 mm / min.
It is said that a peeling force of about m width is required. Further, it is known that even if the adhesive has an appropriate adhesive force in the initial stage of the application, the adhesive force remarkably increases due to a change with time after the application (adhesion progress).

When the adhesive strength of the surface protection film increases,
There are problems that it becomes difficult to peel from the adherend, that the peeling work takes time, that if it peels off rapidly, adhesive residue occurs, and the base film is broken.

In particular, when the adherend is a heavy material such as a metal plate and is stacked and stored with the surface protective film attached, the metal plate increases with time. When the load of itself (generally said to be 50 ton / m ² ) is applied, peeling of the surface protective film becomes more difficult.

When the adherend is a metal plate, the surface protection film is usually peeled at a peeling speed of 5 to 40 m / min. Under such a high speed peeling condition, the peeling force is 300.
There is a problem in that the width exceeds g / 25 mm and the peeling work is hindered.

In order to solve the above-mentioned problems, a mixture containing an ethylene-based copolymer, a tackifying resin and a stabilizer on one side of a base material such as polyolefin is added with a compound represented by the general formula A-B-A (where A is Is a styrene polymer block, B is a butadiene polymer block or an isoprene polymer block), and a pressure-sensitive adhesive prepared by blending a styrene-butadiene-styrene block copolymer and a styrene-isoprene-styrene block copolymer. A composition is disclosed (Japanese Patent Publication No. 1-26389).

[0009]

However, in the above-mentioned pressure-sensitive adhesive composition, the adherend is a heavy material such as a metal plate,
High-speed peelability can be obtained even under the condition that they are stacked and stored, but there is a problem that the initial adhesive strength is remarkably reduced.

The present invention has been made in view of the above-mentioned drawbacks, and an object thereof is to provide a high initial speed even when it is stored in a state in which pressure is applied to an adherend after being applied. It is to provide a surface protective film having a small peeling force when peeled by.

[0011]

The surface protective film of the present invention is a surface protective film having a pressure-sensitive adhesive layer formed on one surface of a base film made of a polyolefin resin, wherein the pressure-sensitive adhesive layer is the above-mentioned base. The material is coextruded at the same time when the material is molded, and the pressure-sensitive adhesive layer has a structure represented by the general formula A-B-A (wherein A is a styrene polymer block, B is a butadiene polymer block, an isoprene polymer block, or these are hydrogenated). The olefin polymer block thus obtained) is formed of a pressure-sensitive adhesive composition comprising a block copolymer represented by (1), a tackifying resin, and an ethylene-butene copolymer.

The present invention will be described in detail below. Examples of the polyolefin resin forming the base film used in the present invention include low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, ethylene-α-olefin copolymer and ethylene-ethyl acrylate copolymer. Polymer, ethylene-vinyl acetate copolymer,
Ethylene-methyl methacrylate copolymer, ethylene-
Examples thereof include n-butyl acrylate copolymer, polypropylene (homopolymer, random copolymer, block copolymer) and the like, and these may be used alone,
Two or more kinds may be used in combination.

The pressure-sensitive adhesive composition used in the pressure-sensitive adhesive layer used in the present invention comprises a block copolymer, a tackifying resin and an ethylene-butene copolymer.

The above block copolymer has the general formula AB-
It is represented by A. In the above general formula, A represents a styrene polymer block, B represents a butadiene polymer block, an isoprene polymer block, or an olefin polymer block obtained by hydrogenating these.

In the block copolymer represented by the general formula ABA, a part of A is represented by the general formula A ', and B
May be partially replaced with the block copolymer represented by the general formula B ′.

Examples of the block copolymer include:
Styrene-butadiene-styrene (hereinafter referred to as S-B-S) block copolymer, styrene-isoprene-styrene (hereinafter referred to as S-I-S) block copolymer, styrene-ethylene-butylene-styrene (hereinafter referred to as S-E) -B
Block copolymers and the like).

In the block copolymer represented by the general formula ABA, the styrene polymer block represented by A or A'has a weight average molecular weight of 12,000 to 100,
Those having a glass transition point of 20 ° C. or higher are preferable.

The butadiene polymer block represented by B or B ', the isoprene polymer block, or the olefin polymer block obtained by hydrogenating these is
The weight average molecular weight is preferably 10,000 to 300,000, and the glass transition point is preferably −20 ° C. or lower.

Further, in the block copolymer represented by the general formula ABA, the weight ratio of the constituent components A and A'to the constituent components B and B'is A / B or [(A + A '). /
(B + B ′)] = 5/95 to 50/50 is preferable, and more preferably 10/90 to 30/70.

As the above tackifying resin, for example, aliphatic hydrocarbon resin, terpene resin, coumarone-indene resin, aromatic hydrocarbon resin, rosin resin and the like are preferably used.

In the pressure-sensitive adhesive composition, when the amount of the tackifying resin used is small, sufficient tackiness cannot be obtained, and when the amount is large, the cohesive force is lowered.
It is limited to 10 to 200 parts by weight, preferably 10 to 1 part by weight based on 100 parts by weight of the block copolymer represented by B-A.
It is 00 parts by weight.

In the pressure-sensitive adhesive composition, when the amount of the ethylene-butene copolymer used is small, the peeling force at the time of peeling at a high speed after storage under pressure is large, and when the amount is large, sufficient adhesiveness is obtained. Is not obtained and spontaneously peels off, so the block copolymer 100 represented by the above general formula ABA.
The amount is limited to 30 to 300 parts by weight, preferably 30 to 200 parts by weight.

If desired, additives such as antioxidants and ultraviolet absorbers may be added to the pressure-sensitive adhesive composition.

The surface protective film of the present invention can be obtained by coextruding the pressure-sensitive adhesive layer at the same time when the base film is extruded. Examples of the coextrusion molding method include a multilayer inflation method and a multilayer T-die method.

The above-mentioned surface protection film does not necessarily have to be two layers of a base film and an adhesive layer, and one or more intermediate layers are provided between the base film and the adhesive layer. Good.

The thickness of the surface protective film is not particularly limited as long as it can protect the adherend from scratches, stains, etc.
0 to 300 μm is preferable.

[0027]

In the surface protective film of the present invention, the pressure-sensitive adhesive layer is formed from the pressure-sensitive adhesive composition comprising the block copolymer, the tackifying resin and the ethylene-butene copolymer, and the pressure-sensitive adhesive layer is applied to the substrate. Since the wettability is improved, the initial adhesiveness is excellent, and the storage elastic modulus of the pressure-sensitive adhesive layer is increased, so that the peelability at high speed is improved.

[0028]

EXAMPLES Examples of the present invention will be described below. (Example 1) 100 parts by weight of an S-E-B-S block copolymer ("Clayton G1657" manufactured by Shell Chemical Co., Ltd.) was added to a tackifying resin ("Arcon P-10 manufactured by Arakawa Chemical Co., Ltd.").
0 ") 100 parts by weight, ethylene-butene copolymer (" Toughmer A4085 "manufactured by Mitsui Petrochemical Co., Ltd.) 30 parts by weight, and an antioxidant (" Irganox 101 manufactured by Ciba Geigy ").
0 ") 1 part by weight of an adhesive composition having a thickness of 60 μm
Low density polyethylene (Mitsui Petrochemical's "Mirason 1
6 ”) A surface protection film was obtained by forming the film on the substrate by a T-die coextrusion method so as to have a thickness of 20 μm.

Example 2 Example 2 was repeated except that an S—B—S block copolymer (“Toughprene A” manufactured by Shell Chemical Co., Ltd.) was used instead of the S—E—B—S block copolymer. A surface protective film was obtained in the same manner as in Example 1.

Example 3 An S-I-S block copolymer ("Califlex TR1102" manufactured by Shell Chemical Co., Ltd.) was used in place of the S-E-B-S block copolymer. A surface protective film was obtained in the same manner as in Example 1.

Example 4 Ethylene-butene copolymer 2
A surface protective film was obtained in the same manner as in Example 1 except that 100 parts by weight was used.

Comparative Example 1 A surface protective film was obtained in the same manner as in Example 1 except that no ethylene-butene copolymer was used.

(Comparative Example 2) Ethylene-butene copolymer 2
A surface protective film was obtained in the same manner as in Example 1 except that 0 part by weight was used.

(Comparative Example 3) Ethylene-butene copolymer 3
A surface protective film was obtained in the same manner as in Example 1 except that 50 parts by weight was used.

Comparative Example 4 The procedure of Example 1 was repeated except that an ethylene-propylene copolymer (“Tufmer XR-111T” manufactured by Mitsui Petrochemical Co., Ltd.) was used in place of the ethylene-butene copolymer. A surface protective film was obtained.

(Comparative Example 5) Instead of the ethylene-butene copolymer, low density polyethylene ("LK-" manufactured by Mitsubishi Petrochemical Co., Ltd.) was used.
30 ″) was used, and a surface protective film was obtained in the same manner as in Example 1.

[Evaluation of Surface Protective Film] The surface protective films obtained in the above Examples and Comparative Examples were subjected to the following adhesive strength test, and the results are shown in Table 1. (1) Adhesion Test Immediately After Adhesion A surface protective film was adhered to a color steel plate, and the adhesive strength immediately after application was measured by a 180-degree peeling method according to JIS Z0237 at a peeling speed of 300 mm / min. (2) Adhesive force test after 7 days (under no load) After sticking the surface protection film on the color steel plate, the plate was left without load for 7 days, and the adhesive force was measured by a 180 degree peeling method according to JIS Z0237. It was measured at a peeling speed of 300 mm / min. (3) Adhesive strength test after 7 days (under load) After the surface protection film was attached to the color steel plate, it was left for 7 days under a load of 50 ton / m ² to determine the adhesive strength to JI.
According to S Z0237, it was measured by a 180 degree peeling method at a high peeling speed of 10 m / min. (4) Adhesive strength test after 7 days (under load) After sticking the surface protection film on the color steel plate, the adhesive strength was left to stand for 7 days under a load of 50 ton / m ² to determine the adhesive strength to JI.
According to S Z0237, a 180 degree peeling method was used to measure at a high peeling speed of 40 m / min.

[0038]

[Table 1]

[0039]

EFFECTS OF THE INVENTION The surface protective film constitution of the present invention is as described above, has a proper initial adhesiveness, and is easy to operate at high speed even when stored in a state where a load is applied to an adherend after attachment. Can be peeled off.

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Claims (1)

[Claims] 1. A surface protective film comprising a base material film made of a polyolefin resin and a pressure-sensitive adhesive layer formed on one surface of the base material film, wherein the pressure-sensitive adhesive layer is coextruded at the same time when the base material is molded, and has a pressure-sensitive adhesive property. The agent layer has a general formula A-B-A (wherein A represents a styrene polymer block, B represents a butadiene polymer block, an isoprene polymer block, or an olefin polymer block obtained by hydrogenating these). A surface protection characterized by being formed from a pressure-sensitive adhesive composition comprising 100 parts by weight of a block copolymer represented by the following formula, 10 to 200 parts by weight of a tackifying resin, and 30 to 300 parts by weight of an ethylene-butene copolymer. the film.