Surface protective film

Abstract

The present invention provides a surface protective film which has proper adhesion property even for an adherend having a rough surface, which is excellent in sliding property of a back surface and is excellent also in anti-blocking property and unwinding characteristic (unwinding tension is reduced, no wrinkle or damage occurs even upon the attaching to the adherend, and the easy and high-speed attachment is made possibly). The surface protective film of the present invention comprising a three-layer composite form consists of an adhesive layer, a middle layer and a back surface layer, wherein the adhesive layer consists of a straight chain-form low density polyethylene 35 to 90 wt.%, a styrenic elastomer 5 to 50 wt.% and a tackfier <= 15wt.%, the middle layer consists mainly of a propylenic resin and the back surface layer is composed mainly of a propylenic resin constituting the middle layer and / or different propylenic resin, and the back surface layer has a surface roughness of >= 3 [mu] m by a ten-point mean roughness(Rz).

Description

technical field [0001] The present invention relates to a surface protection film for preventing adhesion of stains or scratches on the surface of an adherend. More specifically, it relates to an adherend having a relatively rough surface, such as a diffusion plate or a diffusion film used in the field of optics, having suitable adhesive properties, and the back surface It is a surface protection film with excellent sliding properties and excellent handling properties such as blocking resistance and unwinding characteristics. Background technique [0002] When processing and transporting synthetic resin sheets, metal sheets, coated steel sheets, and various signs, etc., surface protection films are used to prevent stains from adhering to or scratching the surfaces of these products. [0003] In particular, in recent years, ultra-thin displays such as liquid crystal displays are often used as display devices such as personal computers and televisions. The ultra-thin displays...

AI Technical Summary

Problems solved by technology

[0005] In addition, these surface protection films are usually rolled into a roll to form a roll, and these rolls have a problem that the films are easily blocked because the base layer and the adhesive layer are pressed together by a strong adhesive force. , when the surface protective film is unrolled during use, it is difficult to perform operations such as peeling off

As such a release treatment, the method of previously applying a release agent to the back layer has been used conventionally. However, it is difficult to achieve a strong bond between the release agent and the back layer and to make it easy to separate from the adhesive layer. Therefore, using A method of undercoating a special release agent, or corona-treating the back layer before applying a release agent

However, there are problems in that the coating process of such release treatment becomes complicated, and the yield decreases and the cost increases.

However, in such a method, a part of the silicon-based fine particles is captured by the adhesive layer due to the adhesive properties of the adhesive layer, and there is a problem of causing contamination of the adherend or lowering of the adhesive force.

[0010] In addition, for the method of forming the substrate layer and the adhesive layer by the co-extrusion method and laminating them at the same time, many proposals have been proposed, represented by the above-mentioned patent documents. Among them, a laminated film has also been proposed. The composite film is constituted as an adhesive layer that has suitable adhesiveness for sticking to the surface of the adherend, is easy to peel off when peeled off, and does not pollute the surface of the adherend, and is composed of styrene and diene hydrocarbons. Random copolymers are formed (Patent Document 4, Patent Document 5), but it is difficult to avoid the above-mentioned problem of difficult unwinding caused by blocking during unwinding, and there are common problems that need to be solved with the above-mentioned

[0011] In order to solve such problems in the prior art, the present applicant has proposed a plan for roughening both surfaces of the adhesive layer and the back layer (Patent Document 6), but when desiring to obtain higher adhesive force, sometimes Insufficient effect

[0012] In addition, it is also proposed that the back layer is composed of fluorine-based resin or silicone-based resin and polyolefin (Patent Document 7), but sufficient effect cannot be obtained only by using fluorine-based resin or the like. When storing at high temperature, etc., the adhesive layer and the back layer may easily stick together

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