JPH07188620A - Film for surface protection - Google Patents

Abstract

PURPOSE:To obtain a surface-protecting film which is excellent in initial tack and releasability and does not contaminate the surface of an adherend even when left to stand outdoors over a long period of time. CONSTITUTION:This film is made by forming a pressure-sensitive adhesive layer on one side of a polyolefin resin base layer comprising a film formed from a mixture of 100 pts.wt. polyolefin resin, 10-30 pts.wt. titanium oxide and 0.1-5 pts.wt. ultraviolet absorber.

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 a coated steel plate, a synthetic resin molded product, or an automobile.

[0002]

2. Description of the Related Art Conventionally, in order to prevent contamination and external damage of painted steel plates, stainless steel plates, aluminum sash plates, machine parts, metal household products, synthetic resin molded products, etc. (1) Polyester resin, chloride A laminate in which a base material such as vinyl resin or polyethylene resin is coated with a releasable rubber-based or acrylic-based pressure-sensitive adhesive, or (2) a polyolefin-based resin containing 0.1 to 5 inorganic fine particles such as titanium oxide. Adhesive tape for surface protection, which is obtained by applying a pressure-sensitive adhesive to a polyolefin resin film having 10% by weight of ultraviolet ray transmittance of 10% or less at a wavelength of 300 to 360 nm (JP-A-4-153).
287) and the like have been proposed.

However, coated steel sheets, synthetic resin molded products, automobiles for export, etc. may be temporarily stored outdoors for several months to a year before reaching the demand of consumers. In such a case, ( When a laminate such as 1) is used as a surface protection film, a difference occurs in the coating surface state between the part that is not in close contact and the part that is not (the part containing air bubbles) during temporary storage, and the surface protection film is peeled off. After that, it has a problem that it appears as a pattern with different gloss. or,
When the pressure-sensitive adhesive tape of (2) is used, the ultraviolet rays and visible rays are not sufficiently shielded, heat deterioration of the pressure-sensitive adhesive occurs, and the pressure-sensitive adhesive remains on the coated surface of the adherend after peeling the pressure-sensitive adhesive tape. There was a problem of adhesive residue. In the case of this (2), the shielding property against ultraviolet rays and the like is improved by increasing the addition amount of the inorganic fine particles, but on the contrary, a new problem such as contamination due to bleeding of the fine particles on the surface occurs.

[0004]

Even when left outdoors for a long period of time, the base material and the adhesive are not deteriorated, the coated surface of the adherend is not affected, and the compounding agent bleeds out. Providing a surface protection film that never happens.

[0005]

The present inventors have completed the present invention by finding that the above problems can be solved by blending a specific amount of titanium oxide and an ultraviolet absorber in a polyolefin resin. That is, the gist of the present invention is that a polyolefin-based resin base layer formed by mixing 10 to 30 parts by weight of titanium oxide and 0.1 to 5 parts by weight of an ultraviolet absorber with 100 parts by weight of a polyolefin-based resin to form a film. And a pressure-sensitive adhesive layer formed on one surface thereof.

The present invention will be described in detail below. Examples of the polyolefin resin used in the present invention include polyethylene, polypropylene, polyethylene / polypropylene block copolymers, ethylene / vinyl acetate copolymers, and mixtures thereof. As the titanium oxide, rutile type titanium oxide is preferable because it has good weather resistance, and the titanium oxide is preferably the polyolefin resin 1
10 to 30 parts by weight, preferably 10 to 100 parts by weight
Add 20 parts by weight. If the amount of titanium oxide is less than 10 parts by weight, the ultraviolet and / or visible light is not sufficiently shielded, and the pressure-sensitive adhesive is deteriorated.
Removability of "(film)" and coating surface contamination prevention property after film peeling are inferior, and when it is more than 30 parts by weight, titanium oxide bleeds out, the initial adhesive strength of the film decreases, and coating after peeling The surface contamination preventive property is also inferior.

The ultraviolet absorber has a wavelength of 290 to 38.
Any one having an absorption maximum at 0 nm may be used,
Conventionally known ultraviolet absorbers such as 2-hydroxy-4
-Methoxybenzophenone, 2-hydroxy-4-n-
Octyloxybenzophenone, 2-hydroxy-4-
n-dodecyloxybenzophenone, 2,2 ', 4
Benzophenone-based UV absorbers such as 4'-tetrahydroxybenzophenone; 2- (2'-hydroxy-3'-
Methylphenyl) benzotriazole, 2- (2'-hydroxy-3'-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5-chloro Benzotriazole, 2- (2'-hydroxy-3'-tert-
Butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'-methylphenyl) -5-butoxycarbonylbenzotriazole and other benzotriazole ultraviolet absorbers; phenyl salicylate, p- Examples include salicylic acid ester-based UV absorbers such as tert-butylphenyl salicylate, p-methylphenyl salicylate, and p-octylphenyl salicylate, but they have good compatibility with polyolefin-based resins and little pollution to coated steel sheets. Therefore, a benzophenone type ultraviolet absorber is preferable. The ultraviolet absorber is 0.1 per 100 parts by weight of the polyolefin resin.
-5 parts by weight, preferably 0.2-3 parts by weight.

When the amount of the ultraviolet absorber is less than 0.1 parts by weight, the ultraviolet ray is not sufficiently shielded, the adhesive is deteriorated, and the removability of the film and the prevention of the coating surface contamination after the peeling are deteriorated. If it is more than 5 parts by weight, the ultraviolet absorbent may bleed out. If both or one of the titanium oxide and the ultraviolet absorber is not blended or if the prescribed blending amount is not met, the weather resistance becomes insufficient,
When the surface protective film is peeled off after outdoor use, the deteriorated adhesive may remain on the coated steel plate or the like. Further, when the content exceeds a predetermined amount, there is a problem that when the film is peeled off, the coated steel sheet and the like are contaminated and the gloss is reduced.

After blending the above-mentioned titanium oxide and ultraviolet absorber with a polyolefin resin, a film is formed by a conventionally known method, for example, a commonly used extruder such as a T-die and an inflation device, and a polyolefin resin substrate layer. (Hereinafter referred to as "base material layer"). The thickness of the base material layer is
It may be appropriately determined depending on the compound and the use, but usually 20 to
It is about 150 μm. If the thickness is less than 20 μm, the resistance to external damage may be poor, and if it exceeds 150 μm, the lapping property may be poor or the economy may be poor, which is not preferable.

The light transmittance of the base material layer of the present invention is such that the ultraviolet (300 to 360 nm) transmittance is 5% or less, preferably 2% or less, particularly preferably 1% or less. Good, and visible part (400-700nm)
Has a transmittance of 50% or less, preferably 3
It is preferably 0% or less, more preferably 20% or less.

The pressure-sensitive adhesive used in the present invention is preferably a rubber-based pressure-sensitive adhesive because it has good removability and is less likely to leave an adhesive residue, and natural rubber-based or synthetic rubber-based adhesives can be used. Examples of the synthetic rubber-based pressure-sensitive adhesive include pressure-sensitive adhesives made of isobutylene-isoprene copolymer and polyisobutylene. To form a pressure-sensitive adhesive layer on the base material layer, a coating solution prepared by dissolving the pressure-sensitive adhesive in a soluble solvent such as toluene is applied on the base material layer by a usual method such as a reverse coating method and dried. do it. In addition, known additives such as antioxidants, light stabilizers, antiblocking agents, and lubricants can 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.

[0012]

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 Polypropylene (PF341, manufactured by Mitsubishi Kasei Co., Ltd.) 10
0 parts by weight of titanium oxide (R-83 manufactured by Ishihara Sangyo Co., Ltd.)
0) 15 parts by weight and 1 part by weight of an ultraviolet absorber (benzophenone-based, American Cyanamide, UV-531) are mixed to form a film having a thickness of 50 μm by a T-die method. Then, a substrate layer film was obtained. Butyl rubber adhesive (manufactured by Exxon Chemical Co., Ltd., IIR: 100 parts by weight, Vistanex L)
(M: 50 parts by weight, toluene: 450 parts by weight) was applied by a reverse coating method to a thickness of 10 μm after drying to obtain a surface protective film.

Example 2 90 parts by weight of polypropylene (PF341), 10 parts by weight of low-density polyethylene (F141 manufactured by Mitsubishi Kasei Co., Ltd.), 18 parts by weight of titanium oxide (R-830), and an ultraviolet absorber (UV-531). A resin composition containing 0.6 part by weight was formed into a film having a thickness of 40 μm by a T-die method to obtain a substrate layer film. A polyisobutylene adhesive (LM-M manufactured by Tonex Co., Ltd.) is added to the base layer film.
H-LC: 100 parts by weight and Exxon Chemical Co., Ltd., Vistanex LM: 50 parts by weight and toluene 450 parts by weight) are applied by a reverse coating method to a thickness of 15 μm after drying, and a surface protective film Got

Comparative Examples 1 to 6 In the same manner as in Example 1, except that the amounts of titanium oxide (R-830) and ultraviolet absorber (UV-531) used in Example 1 were changed to those shown in Table 1. A surface protection film was obtained.

Comparative Example 7 A substrate layer film was formed in the same manner as in Example 1, and an acrylic pressure-sensitive adhesive (SK Dyne 1491, manufactured by Soken Chemical Co., Ltd.) was formed thereon.
H) was dried and then applied to a thickness of 10 μm to obtain a surface protective film.

The (average) light transmittances of the substrate layer films obtained in the above Examples and Comparative Examples were measured, and the surface protective films were evaluated for initial adhesive strength, removability and paint surface contamination prevention after peeling. The results are shown in Table-2. 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 and prevention of paint surface contamination after peeling A surface protective film is attached to a coated steel sheet and exposed outdoors for 6 months, then the film is peeled off, and removability at that time and prevention of contamination on the coated surface The sex was evaluated. The evaluation criteria are as follows.

Removability ○ ・ ・ ・ Good (no adhesive residue left) △ ・ ・ ・ Slight adhesive residue left × ・ ・ ・ A large amount of adhesive residue Paint surface contamination prevention property ○ ・ ・ ・ Good (no change in appearance) △: Minor change in appearance ×: Significant change in appearance --- Unable to evaluate due to residual adhesive

[0019]

EFFECTS OF THE INVENTION The surface protective film of the present invention is excellent in initial adhesive strength and removability, and is coated without contaminating the coated surface of the adherend even when it is left outdoors for a long time. Extremely useful as a steel plate, synthetic resin molded product, or surface protection film for automobiles, etc.

[0020]

[Table 1]

[0021]

[Table 2]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B32B 27/32 Z 8115-4F // C08K 3/22 C08L 23/02 KEC

Claims (2)

[Claims] 1. A polyolefin resin of 100 parts by weight, titanium oxide of 10 to 30 parts by weight, and an ultraviolet absorber of 0.1 to 5 parts by weight.
A surface protection film comprising a pressure-sensitive adhesive layer formed on one surface of a polyolefin-based resin base material layer prepared by blending parts by weight. 2. The surface protective film according to claim 1, wherein the adhesive is a rubber-based adhesive.