JPH0925465A - Surface-protection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a surface-protection film having moderate initial tackiness even to an adherend such as a synthetic resin plate having surface roughness, stably keeping the tacky adhesive force at high temperature and after aging and easily peelable without leaving residual adhesive on the adherend. SOLUTION: A tacky adhesive layer is formed on one surface of a substrate film composed of a polyolefin resin. The tacky adhesive layer is composed of an ethylene-α-olefin copolymer and a hydrogenated resin of a styrene-based random copolymer composed of 7-45wt.% of a styrenic monomer and 93-55wt.% of butadiene. The content of the hydrogenated resin of the styrene-based random copolymer in the tacky adhesive is 20-80wt.%.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a film for protecting the surface of a metal plate such as a stainless plate or an aluminum plate, a coated metal plate, a synthetic resin plate, a glass plate or a vinyl chloride laminated steel plate, In particular, the present invention relates to a surface protective film that protects the surface processed into an embossed plate, a mat plate or the like or the surface subjected to hairline processing.

[0002]

2. Description of the Related Art Conventionally, as a surface protection film, polyvinyl chloride, polyethylene, etc. have been used to prevent scratches on the surface of metal plates, synthetic resin plates, decorative plates, etc. during cutting, transportation and transportation. A surface protective film in which an adhesive layer containing ethylene / vinyl acetate copolymer, acrylic resin, natural rubber or the like as a main component is provided on one surface of a base film such as polypropylene or paper is often used.

Further, one or both surfaces of a metal plate, a synthetic resin plate, a decorative plate, etc. are subjected to hairline processing, mat processing,
For an embossed resin plate with irregularities on the surface, as a pressure-sensitive adhesive that is easily plastically deformed at room temperature, a natural rubber, which is called glueing, and a tackifier are dissolved in a solvent, and the base is applied by bar coating or the like. The surface protection film applied to the material film is used.

Further, it has a suitable adhesive force to a surface having irregularities having different surface roughness, and the adhesive force does not change with time even if it is exposed to high temperature or is applied for a long period of time.
There has been a demand for a surface protective film that can be easily peeled off when not needed, has no adhesive residue, does not break the substrate, does not release chlorine gas even when incinerated, or does not use a solvent.

Therefore, in order to solve the above problems, Japanese Patent Publication No. 58-30911 and Japanese Patent Laid-Open No. 61-103975.
On one side of the base film such as polyolefin,
A block copolymer of the general formula AB (wherein A represents a styrene polymer block, B represents a butadiene polymer block, an isoprene polymer block, or an ethylene / butylene copolymer block) and a tackifier. There is disclosed a surface protective film having a pressure-sensitive adhesive layer formed by mixing and.

However, when a pressure-sensitive adhesive layer composed of a block copolymer and a tackifier is attached to the surface protective film, the content of the block copolymer in the pressure-sensitive adhesive composition is large, and therefore, immediately after the attachment. Adhesive strength is already quite high, and if it changes over time during transportation and storage, or if the adherends are stacked,
When left at a high temperature of about 0 ° C., there is a problem that the adhesive force further increases and peeling is difficult.

As a method of improving them, Japanese Patent Laid-Open No. 6-
JP-A-240216 discloses a pressure-sensitive adhesive layer containing an ethylene-α-olefin copolymer and / or a propylene-α-olefin copolymer as a main component. There is disclosed a surface protective film which does not cause a significant rise.

However, this surface protection film is
It is effective for mirror plates such as metal plates, synthetic resin plates, decorative plates, etc. or comparatively smooth surfaces with a small center average roughness (for example, less than 1 μm), but the surfaces are hairline processed, matted, embossed A metal plate or a resin plate having unevenness on the surface (for example, center line average roughness (JIS
-B0601) Ra having a Ra of about 1 to 3 μm) has a problem that it is difficult to adhere.

[0009]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention The present invention has been earnestly studied in order to solve the above problems, and as a result, an appropriate initial adhesive force (for example, 200 g to 500 g / 50 m) has been obtained.
m), the adhesive strength does not increase with time even if it is exposed to high temperatures or is applied for a long period of time, and it can be easily peeled off when not in use, leaving no adhesive residue on the adherend. It is an object of the present invention to provide a surface protection film which does not break.

[0010]

Means for Solving the Problems In the surface protection film of the present invention for this purpose, a pressure-sensitive adhesive layer is formed on one side of a base film made of a polyolefin resin, and the pressure-sensitive adhesive layer is formed of ethylene-α-olefin. A pressure-sensitive adhesive for a hydrogenated resin of a styrene-based random copolymer, comprising a polymer and a hydrogenated resin of a styrene-based random copolymer composed of 7-45% by weight of a styrene-based monomer and 93-55% by weight of butadiene. It is characterized in that the content therein is 20 to 80% by weight.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as the polyolefin resin forming the base film, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene (LLD-PE), ethylene-
α-olefin copolymer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-
Methyl methacrylate copolymer, ethylene-n-butyl acrylate copolymer, polypropylene and the like can be used, and a mixture of two or more of these polyolefin resins may be used.

Ethylene used in the pressure-sensitive adhesive layer of the present invention
The α-olefin copolymer has an ethylene content of 30% by weight or more, preferably 40% by weight or more, more preferably 50% by weight or more, and propylene, butene-1, hexene-1,4-methylpentene-1, It is a copolymer with octene-1 and the like. Of these, a copolymer of propylene and butene-1 may be used alone or as a mixture, but an amorphous or low crystalline copolymer is preferred.

The hydrogenated resin of the styrene-based random copolymer used in the pressure-sensitive adhesive layer of the present invention means 7 to 45% by weight of styrene-based monomer, preferably 7 to 35% by weight, more preferably 7 to 20% by weight. % And butadiene 93 to 55% by weight, preferably 93 to 65% by weight, more preferably 97.
It is a hydrogenated resin of a copolymer with .about.80. When the amount of the styrene-based monomer is less than 7% by weight, the handleability as a resin becomes poor, and when the amount of the styrene-based monomer exceeds 45% by weight, the resin becomes hard. Further, the hydrogenation rate of the copolymer is 95% or more, preferably 97% or more. Also,
These resins are classified into a block type and a random type depending on the polymerization method, but the random type is preferable from the viewpoint of adhesiveness to an embossed plate or mat plate having irregularities.

The block type of the styrene copolymer hydrogenated resin is a hydrogenated block copolymer of styrene or α-methylstyrene and butadiene. Hydrogenated block copolymers of styrene and butadiene are commonly called SEBS (styrene / ethylene / butylene / styrene) resins. Further, the random type of the hydrogenated resin of the styrene-based copolymer means a block (a) of polystyrene or α-methyl polystyrene and a random copolymer block (b) of styrene or α-methylstyrene and butadiene, if necessary. Is a block copolymer composed of a tapered block (c) of styrene or α-methylstyrene and butadiene, and these are block-bonded.

Further, the difference between the random type and the block type of the styrene copolymer hydrogenated resin is that the block type is a glass near 100 ° C. corresponding to the block (a) of polystyrene or α-methyl polystyrene. While the transition temperature is detected, the random type is in that the glass transition temperature corresponding to (a) is not detected.

The amount of the styrene-based random copolymer hydrogenated resin added to the adhesive is 20 to 80% by weight.
If it is less than 20% by weight, the adhesive strength will decrease, and if it exceeds 80% by weight, an appropriate adhesive strength cannot be obtained.
Limited to 80% by weight.

The surface protective film of the present invention is one in which the above-mentioned pressure-sensitive adhesive is laminated on one side of the substrate film, and any method may be adopted as the laminating method, for example, a substrate film is formed. A method in which a thermoplastic resin and a pressure-sensitive adhesive composition are coextruded and laminated can be adopted.

The thickness of the base material film and the pressure-sensitive adhesive layer constituting the surface protective film is appropriately determined depending on the application, but the thickness of the base material film is 10 to 80 μm, and the thickness of the pressure-sensitive adhesive layer is 5 to 30 μm. Is.

The pressure-sensitive adhesive layer may contain, if necessary, a tackifier, a softener, and a tackifier, as long as the effects of the present invention are not impaired.
UV absorbers, heat resistance stabilizers, antioxidants, weather resistance stabilizers,
The antistatic agent, antiblocking agent, slip agent, pigment, dye, and inorganic / organic filler can be used in combination with additives which are usually added to resins.

[0020]

In the surface protective film of the present invention, the pressure-sensitive adhesive layer is formed from a resin composition composed of an ethylene-α-olefin copolymer and a hydrogenated resin of a styrene-based random copolymer, so An embossed plate,
An appropriate adhesive force is also exhibited on a mat plate or the like, the adhesive force is less promoted even after aging with heating, and is easily peeled off at the time of peeling.

[Measurement Method of Characteristic and Evaluation Criteria] (1) Adhesive Strength Surface protective film is a hairline processed SUS steel plate, mat plate (center line average roughness JIS-B0601: Ra = 1.5)
μm) and a mat plate (center roughness Ra = 2.6 μm) on the surface of the mat plate with a 2 kg pressure roller at 23 ° C., 23
The adhesive strength in each case of ℃ × 30 minutes and 60 ℃ × 7 days was measured according to JIS-Z0237.

(2) Contamination property of adherend surface A surface protective film is a hairline processed SUS steel plate, a mat plate (center line average roughness JIS-B0601: Ra = 1.5).
23 ° C on the surface of the mat plate (Ra = 2.6 μm)
Attach using a 2 kg pressure roller at 23 ° C x 30
The stain resistance of the mat plate after peeling in each case of 60 minutes and 60 ° C. was visually determined. Those that were not contaminated at all were evaluated as ◯, stains were slightly visible, but those that were practical were rated as Δ, and those that were visible and impractical were rated as x.

[0023]

EXAMPLES The present invention will now be described with reference to examples. Examples 1 to 3 (1) Preparation of pressure-sensitive adhesive composition As an ethylene-α-olefin copolymer in the pressure-sensitive adhesive layer, an ethylene-1 butene copolymer (“Tafuma A4085” manufactured by Mitsui Petrochemical Co., Ltd.), styrene-based random As a copolymer hydrogenated resin, "Dynaron 1" manufactured by Nippon Synthetic Rubber Co., Ltd.
320P "was used and the addition amounts were as shown in Table 1. 1.0 part by weight of" Irganox 1010 "manufactured by Ciba-Geig Co., Ltd. as an antioxidant and" Tinuvin manufactured by Ciba-Gaigi Co., Ltd. as an ultraviolet absorber. A pressure-sensitive adhesive composition was prepared by blending 327 ″ 0.5 part by weight.

(2) Preparation of Surface Protective Film The above-mentioned pressure-sensitive adhesive composition and high-density polyethylene (“Sumikasen F6080” manufactured by Sumitomo Chemical Co., Ltd.) for the base material layer were mixed with each other.
The thickness of the base material layer is 5 by melt extrusion molding by the layer coextrusion method.
0 μm, 60 μm so that the thickness of the adhesive layer is 10 μm
A thick surface protection film was produced. The obtained surface protection film was attached to a mat plate having different surface roughness, and the characteristics of the film were evaluated. The results were as shown in Table 1.

Comparative Examples 1 to 4 (Comparative Example 1) As ethylene-α-olefin copolymers,
An adhesive composition was prepared in the same manner as in Example 1 except that the ethylene-1 butene copolymer (“Tafuma A4085” manufactured by Mitsui Petrochemical Co., Ltd.) was 100% by weight.

(Comparative Example 2) A pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 except that 100% by weight of "Dyalon 1320P" manufactured by Nippon Synthetic Rubber Co., Ltd. was used as the hydrogenated resin for the styrene-based random copolymer. Prepared. Table 2 shows the measurement and evaluation results.

(Comparative Example 3) A pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 except that "Tuftec H1052" manufactured by Asahi Kasei Kogyo Co., Ltd. was used instead of the hydrogenated resin of the styrene random copolymer. Table 2 shows the measurement and evaluation results.

(Comparative Example 4) A pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 except that "Tuftec H1041" manufactured by Asahi Kasei Kogyo Co., Ltd. was used instead of the hydrogenated resin of the styrene random copolymer. Table 2 shows the measurement and evaluation results.

As shown in Tables 1 and 2, Examples 1 to 1
Example 3 had an appropriate adhesive force to any mat plate having irregularities. Further, there was little change with time due to high temperature. Further, no contamination of the adherend surface was observed after sticking / peeling.

On the other hand, in Comparative Examples 1, 3, and 4, the surface of the adherend was not contaminated but the tackiness was insufficient for the mat plate having irregularities. In Comparative Example 2, the adhesive strength was too strong, and adhesive residue was left on the surface of the adherend.

Therefore, it can be seen that the surface protective film of the present invention is remarkably excellent in adhesive performance with respect to the mat plate having irregularities.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

The surface protective film of the present invention is obtained by melt-extruding a specific ethylene-α-olefin copolymer and a specific styrene-based random copolymer hydrogenated product in a pressure-sensitive adhesive layer by a two-layer coextrusion method. A film that has a suitable initial adhesive strength to adherends such as synthetic resin plates having irregularities such as hairline processing, matting processing, embossing processing, etc. The adhesive strength does not increase with time even if it is attached, and it can be easily peeled off at the time of peeling, there is no adhesive residue on the adherend, and the base film is not broken.

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Claims (1)

[Claims] 1. A pressure-sensitive adhesive layer is formed on one side of a base film made of a polyolefin resin, and the pressure-sensitive adhesive layer comprises an ethylene-α-olefin copolymer and a styrene monomer 7 to 7.
A styrene-based random copolymer hydrogenated resin composed of 45% by weight and butadiene 93-55% by weight,
The surface protective film, wherein the content of the hydrogenated resin of the styrene-based random copolymer in the pressure-sensitive adhesive is 20 to 80% by weight.