JPH10279896A - Surface-protective film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a surface-protective film suppressed in the buildup of frictional electricity, effectively inhibited from being charged and easily produced by a common plastic film production equipment without the necessity for any special precision apparatus and any complicated processes by laminating a pressure-sensitive adhesive layer on a layer of a base material containing a polyolefin resin and a potassium ionomer resin in a specified ratio. SOLUTION: A pressure-sensitive adhesive layer having a thickness of 5-50 μm is laminated on a 10-100 μm-thick layer of a base material comprising 100 pts.wt. polyolefin resin such as a low-density polyethylene, a medium-density polyethylene, a high-density polyethylene or an ethylene/α-olefin copolymer and 5-30 pts.wt. composition prepared by mixing 100 pts.wt. potassium ionomer with 0.1-30 pts.wt. compound having at least three hydroxyl groups in the molecule and having a molecular weight of 400 or below, desirably 80-300 in such amounts that the total potassium content is 0.4-4 mol, desirably 0,6-2 mol per kg of the potassium ionomer resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a surface protection film.

[0002]

2. Description of the Related Art Surface protection films such as synthetic resin plates, surface-treated metal plates, decorative plywood, painted steel plates, various nameplates, etc. are provided with a surface protective film to prevent contamination of the plate surface such as dust adhesion and scratching. Has been temporarily attached to the surface. When the surface protective film is temporarily attached to one or both surfaces of these adherends, or after the temporary attachment, when these adherends are transported or subjected to various processing, the surface protective film temporarily attached Because the friction between the workbench and the adherend occurs repeatedly on the film surface,
The generated static electricity is stored on the surface protective film surface and has a considerable voltage.

[0003] As described above, the static electricity stored on the surface protective film surface and having a considerable voltage absorbs dust in the air, and rubs on a hard base while the dust thus attracted remains attached. When transported, the surface of a product or a semi-finished product as an adherend may be damaged.
Further, even if there is no damage due to the above-mentioned scratches or dust adsorption, there is a problem that an operator who handles these products or semi-finished products deteriorates work efficiency due to the electric shock caused by the static electricity.

[0004] In order to solve the problems caused by static electricity of plastic products in various fields, proposals have been made to impart conductivity to the surface protective film. For example, JP-A-2-295732 discloses that a conductive thin layer made of a metal or a metal oxide is provided on one surface of a base film, and sorbitan monolaurate is formed on the conductive thin layer as a scratch-resistant coating layer. UV-curable hard coating agent using acrylic resin or urethane-modified acrylic resin mixed with surfactant-based antistatic substance such as glycerol and stearic acid monoglyceride, thermosetting hard coating agent using silicone resin as main agent An antistatic plastic sheet provided with a protective coating layer consisting of:

The plastic sheet for antistatic disclosed in Japanese Patent Application Laid-Open No. 2-295732 discloses a surfactant-based electrically conductive thin layer provided on one side of a substrate film made of metal or metal oxide. Although a protective coating layer mixed with an inhibitor is provided, in order to produce the above-described antistatic plastic sheet, equipment for uniformly mixing a matrix component made of a thermosetting resin or the like forming the protective coating layer is used. In addition, it requires highly accurate equipment for forming the protective coating layer, such as an apparatus for uniformly coating the conductive thin layer, and various manufacturing steps. Furthermore, it is considerably difficult to uniformly disperse a surfactant-based antistatic agent in a matrix component made of a thermosetting resin or the like that forms the protective coating layer, and the protective coating layer has a considerable difficulty. There are problems such as unevenness in antistatic performance and loss of antistatic performance in a short time due to bleeding.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above facts, and its object is to
A surface protection film that suppresses the accumulation of static electricity due to friction and can effectively prevent electrification. It can be easily manufactured with ordinary plastic film manufacturing equipment without the need for special precision equipment or complicated processes. It is an object of the present invention to provide a surface protective film that can be used.

[0007]

According to the present invention, 100 parts by weight of a polyolefin resin and a potassium ionomer resin 5 to 5 parts by weight are used.
The gist of the present invention is a surface protective film characterized in that a pressure-sensitive adhesive layer is laminated on a base material layer composed of 30 parts by weight.

The polyolefin resin used in the present invention is not particularly limited. For example, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-α-olefin copolymer Propylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, polypropylene and the like. These may be used alone or as a mixture of two or more.

The potassium ionomer resin comprises a potassium ionomer of an ethylene-unsaturated carboxylic acid copolymer. Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, fumaric acid, monomethyl maleate and monoethyl maleate. , Maleic anhydride and the like, among which acrylic acid and methacrylic acid are particularly preferably used.

The potassium ion of the potassium ionomer resin has a stable ionized structure in the resin, and the static electricity generated in the base layer is quickly discharged and is not stored, so that it exhibits excellent antistatic performance. Can be done. However, an ionomer of an ethylene-unsaturated carboxylic acid copolymer using lithium or sodium instead of the above potassium cannot exhibit sufficient antistatic performance.
Rubidium and cesium are expensive and difficult to use because of their economical efficiency.

Further, the potassium ionomer resin includes:
Total amount of potassium ion is 1k of potassium ionomer resin
A molecular weight of 400 having 3 or more hydroxyl groups in the molecule so as to be 0.4 to 4 mol, preferably 0.6 to 2 mol per g.
Hereinafter, preferably 80 to 300 compounds are blended. These molecules have 3 or more hydroxyl groups in molecular weight 4
Examples of the compound having a molecular weight of 00 or less include glycerin, diglycerin, trimethylolpropane, 1,1,1-tris (hydroxymethyl) ethane, 2,2-di (hydroxymethyl) -1,3-propanediol, sorbitol, 1,3,5-trihydroxybenzene, 1,3,5
-Trihydroxybenzoic acid, tris (hydroxymethyl)
Aminopropane, N, N, N ', N'-tetrakis (2
-Hydroxyethyl) ethylenediamine, N, N,
Polyhydric group-containing compounds such as N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine are exemplified.

The amount of the compound having a molecular weight of 400 or less having at least three hydroxyl groups in the molecule is 0.1 to 30 parts by weight, preferably 1 to 20 parts by weight, per 100 parts by weight of the potassium ionomer resin. I have.

When the total amount of the potassium ions is in the range of 0.4 to 4 mol, preferably 0.6 to 2 mol per kg of the potassium ionomer resin, excellent antistatic performance is exhibited and favorable film properties are exhibited.

If the amount of the potassium ionomer resin is less than 5 parts by weight based on 100 parts by weight of the polyolefin resin, the obtained surface protective film may not have sufficient antistatic properties. If the amount exceeds the weight part, the antistatic performance is saturated,
Not only is it difficult to expect a further antistatic effect, but also there is a risk that the surface of the adherend may not be able to be clearly seen through due to a decrease in transparency.
Limited to parts by weight.

The base material layer is composed of 100 parts by weight of the polyolefin resin and 5 to 30 parts by weight of a potassium ionomer resin. If necessary, for example, an antioxidant, a heat stabilizer, and an ultraviolet absorber may be used. An additive such as a coloring agent may be added. The thickness of the substrate layer is appropriately determined according to the intended use of the obtained surface protective film, but generally about 10 to 100 μm is preferably used.

The pressure-sensitive adhesive used in the present invention comprises:
It can adhere to the above various adherends and can be easily peeled off after completion of various processes such as transfer, bending, drawing, cutting, etc. or application such as sticking and installation, leaving adhesive on the surface of the adherend, The material is not particularly limited as long as it does not damage the body surface by tearing, for example, ethylene-vinyl acetate copolymer, low-density polyethylene, linear low-density polyethylene, ethylene- Ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-α-olefin copolymer, styrene-butadiene-styrene block copolymer, styrene-isoprene-
Styrene block copolymers, styrene-ethylene-butylene-styrene block copolymers, styrene-butadiene random copolymers, hydrogenated styrene-butadiene random copolymers and the like can be mentioned. These may be used alone or as a mixture of two or more.

The above-mentioned pressure-sensitive adhesive may be, for example,
Additives such as antioxidants, heat stabilizers, ultraviolet absorbers and tackifier resins may be added. The thickness of the pressure-sensitive adhesive layer is appropriately determined according to the use of the obtained surface protective film, but generally, about 5 to 50 μm is preferably used.

The method for producing the surface protective film comprising the above-mentioned substrate layer and the pressure-sensitive adhesive layer of the present invention is not particularly limited. For example, a substrate layer extruded by an inflation method or a T-die method may be used. On one side, the pressure-sensitive adhesive solution may be applied and dried to laminate the pressure-sensitive adhesive layer. However, the base material layer component and the pressure-sensitive adhesive layer component may be coated by inflation or T
It may be integrally formed by a multi-layer coextrusion method by a die method. In particular, since the surface protective film obtained by the multilayer coextrusion molding method has more excellent anchoring properties between the base material layer and the pressure-sensitive adhesive layer, both the temporary adhesion property and the peelability after use are good. Also, productivity is better than other methods.

The surface protective film of the present invention is such that the potassium ion of the potassium ionomer resin used in the above composition in the base material layer is extremely stable,
Since static electricity generated by friction can be quickly discharged, an excellent antistatic effect can be obtained.

The surface protective film of the present invention is one wherein the base material layer has the above-mentioned composition, and the coefficient of static friction between the base material surfaces is as small as 0.01 to 0.6. Therefore, the generation of static electricity itself is suppressed by friction.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.

(Examples 1 to 5, Comparative Examples 1 and 2) Medium density polyethylene (manufactured by Mitsui Petrochemicals Co., Ltd., trade name "Neozex 3510F", MFR = 1.6 g / 10 min) and potassium ionomer resin (Mitsui DuPont Polypropylene) Chemical company,
(Product name "SD100", MFR = 6.0g / 10min)
Was dry blended with the composition shown in Table 1 to prepare a base layer component, and the vinyl acetate content of the ethylene-vinyl acetate copolymer was 19% by weight (trade name “Evaflex # 460” manufactured by DuPont-Mitsui Polychemicals, Inc.). And 19% EVA
) Or 7% by weight of vinyl acetate content of ethylene-vinyl acetate copolymer (trade name “Ultracene 537”, manufactured by Tosoh Corporation; hereinafter, abbreviated as 7% EVA) with the composition shown in Table 1. Used as an adhesive layer component.

A surface protection film was prepared using an inflation two-layer co-extruder so that the above-mentioned base layer component had a thickness of 40 μm and the pressure-sensitive adhesive layer component had a thickness of 20 μm.

In order to evaluate the performance of the surface protective films obtained in Examples and Comparative Examples, the surface resistivity, the coefficient of static friction and the transparency were tested by the following methods. The test results are shown in Table 1.

1. Surface resistivity: According to JIS K 6911, a voltage of 500 V was applied to the substrate surface of the surface protective film, and the surface resistivity was measured after one minute.

2. Coefficient of static friction: According to JIS C 6244, the base layer of the surface protective film is 50 mm × 100
mm, a test piece was prepared, and the test piece was fixed on a weight of 1 kg load and placed on the surface of the base layer of the surface protection film so that the base layers were in close contact with each other. The test piece is pulled horizontally with the above weight at a speed of 200 mm / min. The resistance at the start of the movement was read as a load by a load cell, and the coefficient of static friction was calculated by the following equation. Static friction coefficient = (load indicated by load cell) / (load of weight: 1 kg)

3. Transparency (haze): JIS K71
The transparency (haze) was measured using a digital turbidity meter (trade name "NDH-20D") manufactured by Nippon Denshoku Co., Ltd.

[0028]

[Table 1]

As is evident from Table 1, the surface protective films of Examples all have low frictional resistance, exhibit excellent antistatic performance, and have sufficient transparency so that the surface of the adherend can be sufficiently observed. Although the surface protective film of Comparative Example 1 has a large frictional resistance and large generation and storage of static electricity, and the surface protective film of Comparative Example 2 has excellent antistatic performance, The transparency is so low that it is impossible to identify the surface of the body, and none of them is preferable as a surface protective film.

[0030]

Since the surface protective film of the present invention is constituted as described above, the generation of static electricity itself is suppressed by friction and the static electricity generated by friction is quickly discharged. Thus, an excellent antistatic effect is exhibited.

Claims (1)

[Claims] 1. A surface protective film comprising a pressure-sensitive adhesive layer laminated on a base material layer comprising 100 parts by weight of a polyolefin resin and 5 to 30 parts by weight of a potassium ionomer resin.