JPH07179830A - Surface protection film - Google Patents

Abstract

(57) [Summary] [Purpose] Without applying primer treatment or back treatment,
Synthetic resin plate, decorative plate, which has excellent removability and rewindability,
Providing surface protection films for painted steel sheets, etc. A surface protective film having a rubber-based pressure-sensitive adhesive layer formed on one surface of a base material layer made of polypropylene resin, wherein the base material layer is a laminate of two or more layers including a propylene homopolymer layer and a propylene block copolymer layer. A surface protective film, which is a body and has an adhesive layer formed on a propylene block copolymer layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface protective film used for the purpose of preventing contamination and external damage of synthetic resin plates, decorative plywood, coated steel plates and the like.

[0002]

2. Description of the Related Art Conventionally, in order to prevent contamination and external damage of synthetic resin plates, decorative plywood, coated steel plates, etc., thermoplastic resins such as polyester resin, polyvinyl chloride resin, polyethylene resin, etc. A laminated body having a peelable rubber-based or acrylic-based pressure-sensitive adhesive layer is used.

[0003]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention In a laminate in which a releasable pressure-sensitive adhesive layer is formed on a thermoplastic resin substrate as described above, the adhesion (adhesiveness) between the substrate layer and the pressure-sensitive adhesive layer is It becomes important. If this adhesion is not good, when peeling again,
There is a problem that the adhesive layer remains on the adherend side. In order to solve these problems, corona treatment or primer treatment is performed on the surface of the base material layer, but in the case of corona treatment, the effect is small, and in the case of primer treatment, the manufacturing process increases and it is economically disadvantageous. Is.

On the contrary, when the adhesiveness between the base material layer and the pressure-sensitive adhesive layer is good, when the surface protective film is unwound from the wound state which is the storage state, the pressure-sensitive adhesive is applied to the base material layer side of the adjacent film. The phenomenon of being taken is easy to occur. In order to prevent this, a release paper is inserted or a back surface treatment is performed on the base film, but the operation is complicated. Therefore,
There has been a demand for a surface protective film that does not require primer treatment or back treatment.

[0005]

Means for Solving the Problems As a result of intensive studies to overcome the above-mentioned problems, the present inventors have found that the adhesion between the base resin layer and the pressure-sensitive adhesive layer is good without primer treatment. In addition, we have developed a surface protection film that does not require release paper or back treatment. Therefore, the gist of the present invention is that in a surface protective film having a rubber-based pressure-sensitive adhesive layer formed on one side of a base material layer made of a polypropylene-based resin, the base material layer is a propylene homopolymer layer and a propylene block copolymer. A surface protective film, which is a laminate of two or more layers including layers, wherein a pressure-sensitive adhesive layer is formed on the propylene block copolymer layer.

The present invention will be described in detail below. In the present invention, propylene homopolymer refers to isotactic polypropylene that is usually produced industrially,
A melt flow rate of 0.5 to 10 is used.
Further, if necessary, polyethylene may be added in a ratio of within 30% by weight to prepare a mixture.

The propylene block copolymer is a block copolymer of propylene and one or more different monomers, and has a melt flow rate of 0.5.
Use 10 to 10. Ethylene is preferable as a comonomer, and specifically, after polymerizing a propylene homopolymer, ethylene is charged or a propylene / ethylene mixed gas is charged to continue the polymerization to produce a propylene / ethylene copolymer, which is required. Accordingly, a block copolymer to which an elastomer such as EPR (ethylene propylene rubber) is added is used. With respect to the total amount of the copolymer, the amount of the comonomer component to be charged is preferably 1 to 10% by weight, the amount of the elastomer component is preferably 1 to 20% by weight, and the total amount of the comonomer component and the elastomer component is 1 to 30% by weight.
Is preferred. If each component is out of the predetermined range, the adhesiveness to the pressure-sensitive adhesive layer may be insufficient, which is not preferable.
Further, it may be a mixture obtained by adding polyethylene, an ethylene / vinyl acetate copolymer or the like to the propylene block copolymer of the present invention at a ratio within 20% by weight.

As for the layer structure of the base material layer, a two-layer laminate comprising a propylene homopolymer layer as an outer base material layer and a propylene block copolymer layer as an inner base material layer, polyethylene,
It may be a laminate of three or more layers in which a polyolefin resin such as an ethylene / vinyl acetate copolymer or a polypropylene adhesive resin is used as a substrate intermediate layer. The thickness of the base material layer may be appropriately determined depending on the content and the application, but is usually about 20 to 300 μm. If it is 20 μm or less, resistance to external damage may be poor, and if it is 300 μm or more, handleability may be poor. The thickness of each layer of the base layer laminate is not particularly limited, but is preferably 5 μm or more in terms of production.

As the rubber-based pressure-sensitive adhesive used in the present invention, conventionally known ones may be used, and there are natural rubber-based and synthetic rubber-based pressure-sensitive adhesives, specifically, butyl rubber-based and styrene-butadiene rubber-based pressure-sensitive adhesives. Adhesives such as styrene and isoprene rubber can be used. In addition, known additives such as antioxidants, ultraviolet absorbers, light stabilizers, inorganic fine particles, and lubricants may be added to the base material layer and / or the pressure-sensitive adhesive layer within a range that does not impair the object of the present invention. it can.

The substrate layer of the present invention is formed and manufactured by a conventionally known method, for example, an extruder such as a multilayer T die and a multilayer inflation device. Corona treatment may be performed during manufacturing. Further, in order to form the adhesive layer on the base material layer,
A coating solution prepared by dissolving the pressure-sensitive adhesive in a soluble solvent such as toluene may be coated on the substrate by a usual method such as a reverse coating method and dried.

[0011]

EXAMPLES The present invention will be described in detail below based on examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

Example 1 As a propylene homopolymer layer as an outer layer of a substrate, isotactic polypropylene (melt flow rate: 0.
9) 100 parts by weight of an antioxidant (Ciba Geigy, IR
GANOX-1010) 0.5 part by weight of a resin is used, and 5% by weight of polyethylene copolymer, EP is used as the propylene block copolymer layer of the inner layer of the substrate.
Using a resin obtained by adding 0.5 part by weight of an antioxidant (IRGANOX-1010) to 100 parts by weight of a propylene block copolymer (melt flow rate 0.8) containing 10% by weight of R, a two-layer T-die method is used. And each thickness is 25μ
m, the film is formed so that the total thickness of the film is 50 μm, and a polyisobutylene adhesive (LM-M, manufactured by Donex Co., Ltd.)
H-LC 100 parts by weight + Exxon Chemical Co., Vistanex LM 50 parts by weight) was dissolved in a toluene solvent and applied to the inner layer of the base material by a reverse coating method so as to have a thickness of 10 μm after drying, followed by drying to obtain a surface protective film. .

Comparative Example 1 As the substrate layer, the same resin as the substrate outer layer of Example 1 was used, and a film having a thickness of 50 μm was formed by the single-layer T-die method, and the pressure-sensitive adhesive layer was formed in the same manner as in Example 1. It formed, and the surface protection film was obtained. Comparative Example 2 As the base material layer, the same resin as the base material inner layer of Example 1 was used to form a film having a thickness of 50 μm by the single-layer T-die method, and the pressure-sensitive adhesive layer was formed by the same method as in Example 1, A surface protection film was obtained. Comparative Example 3 A two-layer film similar to that used in Example 1 was used as the base material layer, and an acrylic pressure-sensitive adhesive was applied to the inner base material layer to a thickness of 10 μm after drying to obtain a surface protective film.

With respect to the surface protective films obtained in the above Examples and Comparative Examples, the initial adhesive strength, removability and rewindability were evaluated, and the results are shown in Table-1. The evaluation method is as follows. (1) Initial Adhesion Strength The obtained surface protection film was attached to a coated steel sheet (paint; acrylic-melamine resin) and evaluated by 180 ° peel strength according to JIS K6854.

(2) Removability A surface protective film was attached to a coated steel sheet, and the temperature was 70 ° C. × 10.
After being left under the condition of time, the film was peeled off, and the removability at that time was evaluated. The evaluation criteria are as follows. ○: Good (no adhesive remaining) △: Slight adhesive remaining ×: Large adhesive remaining

(3) Rewinding property The surface protective film is left in a wound state at 50 ° C. for 7 days and then rewound at about 10 m / min. evaluated. The evaluation criteria are as follows. ◯: Good (no pressure-sensitive adhesive was picked up on the back surface) △: Slightly picked up ×: Significantly picked up

[0017]

The surface protective film of the present invention is excellent in removability and rewindability without any primer treatment or back surface treatment and is extremely useful as a surface protective film for synthetic resin plates, decorative plywood, coated steel plates and the like. is there.

[0018]

[Table 1]

Claims (2)

[Claims] 1. A surface protective film comprising a base material layer made of polypropylene resin and a rubber-based pressure-sensitive adhesive layer formed on one surface thereof, wherein the base material layer comprises two or more layers including a propylene homopolymer layer and a propylene block copolymer layer. And a pressure-sensitive adhesive layer formed on the propylene block copolymer layer. 2. The surface protective film according to claim 1, wherein the propylene block copolymer contains 1 to 10% by weight of ethylene as a comonomer component.