JPH05186747A - Surface-protecting film - Google Patents

Abstract

PURPOSE:To prepare a surface-protecting film which has a good stickiness, is resistant to degradation in adhesive strength after being stuck, leaves little adhesive behind on the adherend, and exhibits a good weatherability by forming a self-adhesive layer comprising a compsn. comprising a specific thermoplastic elastomer, a tackifier, and an epoxy resin on the surface of a substrate film. CONSTITUTION:A surface-protecting film is prepd. by forming a self-adhesive layer comprising a self-adhesive compsn. comprising 100 pts.wt. thermoplastic acid-modified polystyrene elastomer, 20-150 pts.wt. tackifier, and 0.1-5 pts.wt. epoxy resin on at least one side of a substrate film. The elastomer is prepd., e.g. by acid-modifying a rubber block of a thermoplastic elastomer such as an SEBS(styrene-ethylene/butylene-styrene) rubber or an SBS(styrene-butylene- styrene) rubber. Examples of the tackifier are a hydrogenated rosin ester, a terpene resin, a hydrogenated terpene resin, and a terpene-phenol resin.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a surface protective film. More specifically, the present invention is applied for protecting the surface of a metal plate such as a stainless plate or an aluminum plate, a coated metal plate or a resin plate, a vinyl chloride laminated steel plate, a glass plate, etc. when they are transported, processed or cured. The present invention relates to a surface protection film that has applications such as being attached.

[0002]

[Problems to be Solved by the Prior Art / Invention] The characteristics required for a surface protective film are that the protective film does not float or peel after being attached to an adherend, and the adhesive remains on the adherend when peeled and removed. It means not. In particular, when the substrate is placed under severe conditions such as high temperature or outdoor exposure between the time it is attached to the adherend and the time it is peeled off, the above-mentioned properties are required to be more advanced.

For this reason, as a surface protective film which has been generally used in the past, an acrylic copolymer was crosslinked three-dimensionally with an isocyanate compound or a methylol compound to the extent that the tackiness was not lost, and the cohesive force was increased. Examples thereof include those using a pressure-sensitive adhesive, and those using a pressure-sensitive adhesive in which an appropriate amount of a tackifier or the like is mixed with synthetic rubber, natural rubber or modified natural rubber.

Such a surface protection film causes no particular problem when it is adhered to an adherend such as a metal plate, an aluminum plate, a resin plate, or a coated plate having a relatively flat surface.

However, dioctyl phthalate (D
OP) plastic surface mixed with a plasticizer, such as vinyl chloride laminated steel sheet that has been widely used recently (among others,
When a conventionally known surface protection film is attached to a vinyl chloride laminated steel sheet with a rough surface such as embossed on the surface, the plasticizer bleeds out into the adhesive layer and Problem arises.

(1) When the pressure-sensitive adhesive layer is composed of a pressure-sensitive adhesive composition containing an acrylic copolymer as a main component, the compatibility between the pressure-sensitive adhesive composition and a plasticizer such as DOP is good. Therefore, the plasticizer migrates into the pressure-sensitive adhesive layer, and the cohesive force of the pressure-sensitive adhesive is extremely lost, resulting in a sticky state. Therefore, the adhesive force of the pressure-sensitive adhesive is reduced and the surface protective film floats from the adherend, or when the surface protective film is peeled from the adherend, the adhesive exhibits a stringing phenomenon and remains on the adherend.

(2) In the case where the pressure-sensitive adhesive layer is composed of a composition containing natural rubber or modified natural rubber as a main component and a tackifier, etc., added to the bleed-out of the plasticizer as described above. On the other hand, it is relatively strong. However, since natural rubber and modified natural rubber have unsaturated double bonds in the structure, UV irradiation causes molecular cleavage when exposed to the outside, and when the surface protective film is peeled off, an adhesive is applied to the adherend. Remains.

[0008] The problem to be solved by the present invention is to solve the above-mentioned problems, and in particular, the sticking property is good even on a plastic surface containing a plasticizer, and the adhesive strength after sticking is lowered. An object of the present invention is to provide a surface protective film having little adhesive residue on an adherend and good weather resistance.

[0009]

The surface protection film of the present invention is characterized in that at least one surface of the base film is 100 parts by weight of an acid-modified polystyrene-based thermoplastic elastomer, 20 to 150 parts by weight of a tackifier and 0 epoxy resin. .1
The point is that an adhesive layer made of an adhesive composition containing 5 to 5 parts by weight is provided.

Examples of the acid-modified polystyrene-based thermoplastic elastomer used in the present invention include SEBS (styrene-ethylene / butylene-styrene), SBS (styrene-butylene-styrene), and SIS (styrene-isoprene-styrene) rubber blocks. Examples thereof include those modified with an acid, and examples of the acid for modification include maleic anhydride, stearic acid, and (meth) acrylic acid.

Considering the initial adhesion to the rough surface, the tensile strength of the pressure-sensitive adhesive composition is preferably 300 kg / cm ² or less.

Examples of the tackifier include hydrogenated rosin ester, terpene type resin, hydrogenated terpene type resin, terpene phenol type resin, aliphatic petroleum resin, hydrogenated aliphatic petroleum resin and the like.

Among these tackifiers, compatibility with acid-modified polystyrene-based thermoplastic elastomer, weather resistance,
Considering initial adhesiveness and the like, hydrogenated terpene resins and hydrogenated aliphatic petroleum resins are preferable. The blending amount is 20 to 150 parts by weight with respect to 100 parts by weight of the acid-modified polystyrene-based thermoplastic elastomer. If the tackifier is less than 20 parts by weight, the initial adhesive strength is low and the adhesive tends to peel off, resulting in poor workability. When the tackifier exceeds 150 parts by weight, the adhesive strength is too strong and it is difficult to peel off the adherend after use. The preferred blending amount is 30 to 130 parts by weight, especially 60 to
100 parts by weight.

Examples of the epoxy resin include polyfunctional polyglycidyl amine epoxy resin, polyfunctional polyglycidyl ether epoxy resin, bisphenol epoxy resin, and the like. Especially, in consideration of reactivity and weather resistance, polyfunctional Glycidyl amine epoxy resin is preferred.

The amount of the epoxy resin compounded is 0.1 with respect to 100 parts by weight of the acid-modified polystyrene-based thermoplastic elastomer.
By blending up to 5 parts by weight, it is possible to three-dimensionally crosslink and suppress a decrease in adhesive strength at high temperature due to migration of a plasticizer from an adherend (for example, a vinyl chloride steel plate such as a soft vinyl chloride laminated steel plate). In addition, it is possible to prevent the adhesive from remaining on the adherend. The amount of epoxy resin compounded is 0.
If it is less than 1 part by weight, the crosslinking reaction will not proceed sufficiently and the adhesive will remain on the adherend. On the other hand, if it is 5 parts by weight or more, the crosslink density becomes too high, which causes a problem in the initial adhesiveness at the time of laminating. The preferred blending amount is 0.3 to 2.0 parts by weight, and especially 0.1.
5 to 1.0 parts by weight.

The method for preparing the pressure-sensitive adhesive composition is not particularly limited, and each component may be dissolved in a known aromatic organic solvent and mixed, or may be heated and mixed in a molten state. The pressure-sensitive adhesive composition thus obtained is applied to at least one surface of the substrate film to form a pressure-sensitive adhesive layer. The thickness of the pressure-sensitive adhesive layer is preferably 5 to 50 μm.

The material of the substrate film is not particularly limited, but polyolefin resin, polyvinyl chloride resin, etc. are preferable. The base film may be a single layer film or a laminated film. The thickness of the base film is 20
˜100 μm is preferred.

[0018]

EXAMPLES Next, examples will be shown below in order to specifically describe the present invention. Example 1 A PP / PE (polypropylene / polyethylene) blend film having a thickness of 40 μm was prepared as a base film. 60 parts by weight of hydrogenated aliphatic petroleum resin (Alcon P-100, manufactured by Arakawa Chemical) and epoxy resin (Tetrad C, manufactured by Mitsubishi Gas Chemical Co., Ltd.) per 100 parts by weight of acid-modified SEBS (Tuftec M1911, manufactured by Asahi Kasei) 0.3 parts by weight and 370 parts by weight of toluene as a solvent were added and completely dissolved to obtain an adhesive composition. This pressure-sensitive adhesive composition was applied onto a substrate film so as to have a thickness of 15 μm and dried to obtain a surface protective film.

Example 2 A surface protective film was obtained in the same manner as in Example 1 except that the amount of Alcon P-100 in the pressure-sensitive adhesive composition was changed to 100 parts by weight.

Example 3 In the same manner as in Example 1 except that 80 parts by weight of hydrogenated terpene resin (Clearon P-105, manufactured by Yasuhara Yushi Kogyo Co., Ltd.) was added in place of the Alcon P-100 in the pressure-sensitive adhesive composition. A surface protection film was obtained.

Example 4 A surface protective film was obtained in the same manner as in Example 1 except that the content of Tetrad C in the adhesive composition was 1.0 part by weight.

Comparative Example 1 A surface protective film was obtained in the same manner as in Example 2 except that the tetrad C in the pressure sensitive adhesive composition was omitted.

Comparative Example 2 To 100 parts by weight of 2-ethylhexyl acrylate, 2 parts by weight of acrylic acid, 0.01 part by weight of trimethylolpropane triacrylate, and 0.2 part by weight of benzoyl peroxide as an initiator were added, and the mixture was placed in a toluene solution. Polymerization treatment was performed to obtain an acrylic copolymer solution. 5 parts by weight of trifunctional isocyanate (Coronate L,
(Manufactured by Nippon Polyurethane Co., Ltd.) was added to prepare a pressure-sensitive adhesive composition, and this pressure-sensitive adhesive composition was used to obtain a surface protective film in the same manner as in Example 1.

Comparative Example 3 An adhesive composition was prepared by adding 70 parts by weight of a terpene resin (YS resin Px- # 1150, manufactured by Yasuhara Yushi Kogyo Co., Ltd.) and 3 parts by weight of Coronate L to 100 parts by weight of a methyl acrylate-grafted natural rubber. Then, using this pressure-sensitive adhesive composition, a surface protective film was obtained in the same manner as in Example 1.

Experimental Example The performance of the surface protective films obtained in the above Examples and Comparative Examples was tested, and the results are shown in Table 1.

[0026]

[Table 1]

The performance test of the surface protective film shown in Table 1 was conducted as follows. (1) Initial Adhesion Strength The surface protection film was applied with surface roughness (Rz according to JIS standard).
(10-point average flatness) 22 μm rough surface vinyl chloride laminated steel sheet (20% by weight of DOP in vinyl chloride sheet)
Rolls (pressure 5 kg / cm ² ),
The adhesive force when peeling 180 ° at a pulling speed of 300 mm / min after 30 minutes is shown. The higher the number, the better the sticking property.

(2) After attaching the protective film (60 ° C. ×
2 days storage) It corresponds to about 1-2 months under summer conditions. As the adhesive strength,
If it is not more than 20 g, it will float or peel off. As the evaluation standard of the film floating, the case where the film floating was not visually observed was evaluated as ◯, and the case where the film floating was visually observed was evaluated as x. Also, the presence or absence of adhesive residue was visually observed.

(3) Weather resistance In an accelerated test with a sunshine weather meter, the time until the adhesive remains on the adherend is observed. It is preferably 50 hours or more.

[0030]

The surface protective film of the present invention can be applied to not only adherends such as stainless steel plate, aluminum plate and glass plate, but also to adherends of plastics containing a plasticizer and having a rough surface. However, the sticking property is good, the adhesive strength after sticking is small, the adhesive residue on the adherend is small, and the weather resistance is good, which is extremely practical value.

Claims (1)

[Claims] 1. A base film, on at least one surface of which 100 parts by weight of an acid-modified polystyrene-based thermoplastic elastomer,
20 to 150 parts by weight of a tackifier and 0.
A surface protective film provided with a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive composition containing 1 to 5 parts by weight.