JPH08120233A - Surface protective film for resin plate - Google Patents

Abstract

PURPOSE: To obtain a surface protective film for resin plate improved in antistatic properties by laminating a pressure-sensitive adhesive comprising an ethylene/vinyl acetate copolymer on a base film made of a thermoplastic polyolefin resin and a polyether resin having specified groups. CONSTITUTION: 100 pts.wt. thermoplastic polyolefin resin (e.g. PP) is mixed with 5-30 pts.wt. amide or imide polyether resins having molecular weights of 5000-20000 [e.g. a polyether ester amide resin represented by formula I (j and k are each an integer of 1 or greater) and/or a polyether amide imide resin represented by formula II (m, n and p are each an integer of 1 or greater; and m/p is 3/7-7/3)] to form a uniform mixture. This mixture and a pressure- sensitive adhesive comprising an ethylene/vinyl acetate copolymer of a vinyl acetate content of 5-30wt.% are coextruded by e.g. the T die process to obtain a protective film used for a resin plate and composed of a polyolefin base film of a thickness of about 10-80μm and a pressure-sensitive adhesive layer of a thickness of about 5-30μm laminated thereon.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a surface protective film for a resin plate.

[0002]

2. Description of the Related Art Up to now, polyethylene has been used for the purpose of preventing pollution such as adhesion of dust on the surface of synthetic resin plates, decorative plates, metal plates, etc., and preventing damage during processing and transportation.
A method is known in which a surface protective film obtained by laminating an adhesive on one surface of a polyolefin resin film such as polypropylene is temporarily attached.

However, since the surface protective film and the synthetic resin plate both have high insulating properties due to friction when the surface protective film is attached to the synthetic resin plate and then conveyed or stacked, the surface protective film and the synthetic resin plate are highly insulative. There is a problem that static electricity is easily applied in a dry atmosphere, and as a result, not only electric shock is generated and dust is adsorbed, but also workability is deteriorated due to suction and repulsion between the synthetic resin plates.

As a method for solving the above-mentioned problems, for example, a surface protective film using a film formed by mixing a thermoplastic polyolefin resin with a surfactant and mixing it as a base material is disclosed (Japanese Unexamined Patent Publication No. Hei 4 (1998) -19984). 292943
Issue).

[0005]

However, even when the surface protective film described in the above publication is used, the amount of the surfactant to be added is limited, and a sufficiently satisfactory antistatic property cannot be obtained. If a large amount of surfactant is added to obtain satisfactory antistatic properties, the adhesive performance may decrease due to the surfactant bleeding out into the adhesive during sticking and the adhesive performance such as contamination of the adherend after peeling. There was a problem with aging.

An object of the present invention is to provide a surface protective film for a resin plate, which can sufficiently satisfy the antistatic function of the synthetic resin plate and which does not change the adhesive performance with time during application. .

[0007]

The base film used in the present invention comprises a polyolefin type thermoplastic resin (A) and a polyether type resin (B).

The above polyolefin-based thermoplastic resin (A)
As, for example, low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-α olefin copolymer, propylene-α
Examples thereof include an olefin copolymer, an ethylene-ethyl acrylate copolymer, an ethylene-vinyl acetate copolymer, an ethylene-methyl methacrylate copolymer, and polypropylene. These may be used alone or in combination of two or more.

The above-mentioned polyether resin (B) is a polyether resin having an amide group and / or an imide group in the molecule, and examples thereof include a polyether ester amide resin and a polyether amide imide resin.

The above polyether ester amide resin is derived from a polyamide having carboxyl groups at both terminals derived from ε-caprolactam and an alkali metal salt of 3-isophthalic acid, and an alkylene oxide adduct of bisphenols. And specifically,
Other than those represented by the following general formula (1), derivatives thereof and the like can be mentioned.

[0011]

Embedded image (J and k each represent an integer of 1 or more.)

The above-mentioned polyether amide imide resin is a compound having a polyether as a main chain and containing both an amide group and an imide group in the molecule.
Other than those represented by the following general formula (2), their derivatives and the like can be mentioned.

[0013]

Embedded image (M, n and p each represent an integer of 1 or more, and
m: p is 3: 7 to 7: 3)

If the weight average molecular weight of the above-mentioned polyether resin (B) is small, the cohesive force of the sheet is lowered, and if it is large, the flexibility is impaired.
50,000 is preferable, and more preferably 10,000 to
It is 100,000.

When the amount of the above-mentioned polyether resin (B) added is small, it becomes difficult to obtain sufficient antistatic property, and even when it is increased, only a certain antistatic property is obtained.
From the reason that the productivity becomes low, it is 5 to 35 parts by weight, preferably 15 to 25 parts by weight, relative to 100 parts by weight of the above-mentioned polyolefin-based thermoplastic resin (A).

The essential components of the base film used in the present invention are as described above, but in addition to the above essential components, a light stabilizer such as an ultraviolet absorber, an antioxidant, a filler and the like are added if necessary. May be.

The thickness of the above-mentioned substrate film is appropriately selected depending on the application, but it is preferably 10 to 80 μm from the viewpoint of ease of use.

The surface protective film for a resin plate of the present invention can be obtained by laminating a pressure-sensitive adhesive made of an ethylene-vinyl acetate copolymer on one surface of the above-mentioned substrate film.

When the content of vinyl acetate in the ethylene-vinyl acetate copolymer is low, the adhesiveness of the surface protective film for a resin plate to an adherend cannot be obtained, and the film tends to float or peel off. If the amount is too large, it becomes difficult to obtain removability from the adherend after use. Therefore, it is 5 to 30% by weight, preferably 10 to 20% by weight.

The above-mentioned adhesive includes a tackifying resin, a softening agent,
An ultraviolet absorber, an antioxidant and the like may be added if necessary.

The thickness of the pressure-sensitive adhesive is appropriately selected depending on the intended use, but is preferably 5 to 30 μm from the viewpoint of ease of use.

The method for producing the surface protective film for a resin plate of the present invention is not particularly limited. For example, even if the solution of the pressure-sensitive adhesive is applied to the base film extruded after hot-melting and then dried. Alternatively, the constituent components of the base film and the pressure-sensitive adhesive may be collectively molded by a two-layer coextrusion method using a thermal melting method such as an inflation method or a T-die method.

Examples of the resin plate to which the surface protective film of the present invention is preferably applied include a polycarbonate resin plate, an acrylic resin plate, a vinyl chloride resin plate, an olefin resin plate, an ABS resin plate, and the like. Alternatively, a mixed resin in which these are melt-mixed or a composite resin in which multiple layers are laminated may be used.

[0024]

The base film used in the present invention contains a thermoplastic resin having a specific amount of a polyether resin having a carbonyl group derived from an amide group and / or an imide group in a molecule thereof, and therefore has a carbonyl group. Water in the air is easily coordinated to the unpaired electron pair of the oxygen atom of the base,
When used as a surface protective film for a resin plate, the antistatic property is excellent, and since there is little bleed-out to the adhesive, the adhesive performance does not change with time. Further, since the pressure-sensitive adhesive composed of the ethylene-vinyl acetate copolymer is used, the pressure-sensitive adhesiveness to the synthetic resin plate is good.

[0025]

EXAMPLES Examples of the present invention will be described below. still,
Hereinafter, "part" means "part by weight". (Examples 1 to 5 and Comparative Examples 1 and 2) According to the compounding composition shown in Table 1, first, polypropylene and polyetheresteramide resin were added to 100 parts of polypropylene (trade name "1501F" manufactured by Mitsubishi Kasei Co., Ltd.). 70:30
A homogeneous kneaded product was obtained by adding the melt-mixed resin mixed in (manufactured by Sanyo Chemical Industry Co., Ltd., trade name "Pelestat PP-3170", hereinafter referred to as "Pelestat").

The ethylene-vinyl acetate copolymer has a vinyl acetate content of 19% by weight, "EVA FLEX".
# 460 "(trade name, manufactured by Mitsui DuPont Polychemical Co.,
Hereinafter referred to as "EVA-19"), 28% by weight of "EVA-19"
FLEX # 280 "(trade name, manufactured by Mitsui DuPont Polychemical Co., Ltd., hereinafter referred to as" EVA-28 ") and 7% by weight of" Ultrasen 537 "(trade name, Tosoh Corp.)
Manufactured by the company, hereinafter referred to as "EVA-7") was used as an adhesive.

The uniform kneaded product and the pressure-sensitive adhesive were coextruded by a T-die method to obtain a surface protective film having a polyolefin base film thickness of 60 μm and an ethylene-vinyl acetate copolymer pressure-sensitive adhesive thickness of 10 μm.

(Examples 6 to 10 and Comparative Examples 3 to 4) According to the blending composition shown in Table 2, first, polypropylene and the polyether amide imide resin represented by the above general formula (2) (weight average molecular weight 50,000, m: p = 5: 5, n =
A uniform kneaded product was obtained by melt mixing 5 to 15).

Further, the ethylene-vinyl acetate copolymers used in Examples 1-5 and Comparative Examples 1-2 were used as a pressure-sensitive adhesive. The uniform kneaded product and the pressure-sensitive adhesive were co-extruded by a T-die method to obtain a surface protective film having a polyolefin base film thickness of 60 μm and an ethylene-vinyl acetate copolymer pressure-sensitive adhesive thickness of 10 μm.

[Evaluation Items and Evaluation Methods] The evaluation items and evaluation methods of the surface protective film obtained above are shown below. All operations were performed under the conditions of constant temperature and humidity of room temperature of 23 ° C. and humidity of 65%. (Initial resistance value) The surface protection film obtained above is 30
After leaving for a minute, a high resistance meter (type "432
9A ", manufactured by Yokogawa Hewlett-Packard Co., Ltd.
Table 1 shows the results of measuring the surface specific resistance value (Ω / □) of the base material using.

(Time-dependent resistance value) The surface protective film obtained above was left in the original shape for one week, and then the surface specific resistance value (Ω / □) of the substrate was measured using the above measuring device. It shows in Table 1.

(Initial Adhesive Strength) The surface protective film obtained above was used as a polycarbonate resin plate having a thickness of 2 mm (trade name: “UPILON NF-200” manufactured by Mitsubishi Gas Chemical Co., Inc.).
0 "), using a 2 kg pressure roller, 300 mm /
After leaving it pasted for 30 minutes at the speed of min, J
Table 1 shows the results obtained by measuring the 180 ° peel adhesive strength in a 25 mm width according to IS Z0237. Unit is g / 2
It is 5 mm.

(Adhesion with time) The surface protective film obtained above was left in the original shape for 1 week, and then attached to the polycarbonate resin plate using the pressure roller, and then 25 mm in accordance with JIS Z0237. 18 in width
The results of measuring the 0 ° peel adhesion are shown in Table 1. The unit is g / 25 mm.

(Change in Surface Appearance) Table 1 shows the results of visual observation of the appearance of surface defects such as surface roughness on the surface of the surface protective film obtained above.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

The constitution of the surface protective film for a resin plate of the present invention is as described above, and it is possible to suppress electrostatic charge not only at the initial stage but also after a lapse of time, and there is no adverse effect on the pressure-sensitive adhesive, so that the adhesive strength is improved. Since there is almost no change with time or contamination of the adherend after peeling, it can be suitably used for surface protection of easily-charged resin plates such as synthetic resin plates and composite synthetic resin plates.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B32B 27/28 101 9349-4F // C08L 23/00 LBZ 31/04 LHH 77/12 LQY 79 / 08 LRE

Claims (2)

[Claims] 1. A thermoplastic polyolefin resin (A) 10
The content of vinyl acetate is 5 to 3 on one side of a base film composed of 0 parts by weight and (B) 5 to 30 parts by weight of a polyether resin having an amide group and / or an imide group in the molecule.
A surface protective film for a resin plate, characterized in that a pressure-sensitive adhesive comprising 0% by weight of an ethylene-vinyl acetate copolymer is laminated. 2. The surface protective film for a resin plate according to claim 1, wherein the polyether resin is a polyether ester amide resin or a polyether amide imide resin.