JPH04309585A - Surface-protecting film - Google Patents

Abstract

PURPOSE:To efficiently protect articles covered by the surface-protecting film from electrification. CONSTITUTION:The title film is manufactured by adding an antistatic agent to a pressure-sensitive adhesive layer formed on one side of a thermoplastic resin film. When the film is applied to and then peeled off a highly insulative synthetic resin plate, etc., the level of electrification of the plate can be maintained low afterwards.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface protection film.

0002

[Prior Art] Conventionally, a surface protection film with an adhesive layer formed on one side of a thermoplastic resin film has been used to prevent damage and contamination during processing and transportation of synthetic resin boards, decorative boards, metal boards, etc. .

0003

[Problem to be Solved by the Invention] However, when such a surface protection film is peeled off after being attached to a synthetic resin board, etc., since both the surface protection film and the synthetic resin board have high insulation properties, , especially in a dry atmosphere such as winter, it is easy to be charged with static electricity. When synthetic resin plates are charged, there is a problem in that not only electric shock and dust adsorption occur, but also workability is reduced due to mutual attraction and repulsion between the synthetic resin plates.

[0004] As a method for preventing static electricity, it is generally known to apply an antistatic agent to the surface of the film, but although this method is effective when the surface protection film is attached to the synthetic resin plate, It is impossible to prevent the synthetic resin board from being charged with static electricity when the surface protection film is peeled off from the synthetic resin board and immediately thereafter. Furthermore, the method of kneading an antistatic agent into a film does not provide sufficient antistatic effect.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a surface protection film that can effectively prevent static electricity on a synthetic resin plate.

[0006]

[Means for Solving the Problems] The present invention provides, firstly, a surface protection film comprising an adhesive layer formed on one surface of a thermoplastic resin film, in which an antistatic agent is added to the adhesive layer. Secondly, the antistatic agent is liquid at room temperature.

[0007] The thermoplastic resin used for the base film in the present invention is not particularly limited, but olefin resins such as polyethylene and polypropylene are preferably used.

In the present invention, the resin constituting the adhesive layer is not particularly limited, but includes ethylene-vinyl acetate copolymer, low-density polyethylene, linear low-density polyethylene, ethylene-ethyl acrylate copolymer, and ethylene. −
Examples include methyl methacrylate copolymers, ethylene-α olefin copolymers, and mixtures thereof.

[0009] The antistatic agent used in the present invention is not particularly limited, but the amount added is as low as 1 for the adhesive.
It is preferably 0.05 to 6.0 parts by weight, more preferably 0.1 to 4.0 parts by weight. If it is less than 0.05 parts by weight, the antistatic effect will be insufficient, and if it exceeds 6.0 parts by weight, the antistatic agent that has bled onto the surface of the adhesive layer will remain on the surface of the synthetic resin plate even after peeling off, causing printing problems. This may cause defects, etc.

[0010] Furthermore, the antistatic agent that is liquid at room temperature and is used in the second invention is not particularly limited, and may include cationic surfactants, anionic surfactants, amphoteric surfactants, and nonionic surfactants. Any surfactant may be used. The amount added is 0.1 to 100 parts by weight of the adhesive.
Preferably, the amount is 6.0 parts by weight, and more preferably,
It is 0.2 to 4.0 parts by weight. If the amount is less than 0.1 part by weight, the effect of preventing increase in adhesive strength due to heating will be insufficient, and peeling after heat treatment will become difficult. Moreover, if it exceeds 6.0 parts by weight, it becomes difficult to adhere to a synthetic resin board at room temperature.

[0011]

[Function] The surface protection film of the present invention has an antistatic agent added to the adhesive layer, so it is completely electrically neutralized when applied, and the antistatic agent is appropriately applied to the interface with the board to which it is applied. Because of its presence, polarization does not occur at the adhesive interface between the surface protection film and the synthetic resin plate, and static electricity is less likely to be charged on the surface of the synthetic resin plate when peeled off.

[0012] Furthermore, when an antistatic agent that is liquid at room temperature is added to the adhesive layer, during heat treatment such as printing or vacuum forming, the liquid antistatic agent may be mixed with the adhesive layer and the non-adhesive material. It migrates to the adhesive interface with the synthetic resin board and moderately suppresses the physicochemical affinity between the surface protection film and the synthetic resin board. Therefore, the adhesive strength of the adhesive layer is prevented from increasing due to heat treatment.

[0013]

[Examples] Examples of the present invention will be specifically explained below.
The invention is not limited to the examples.

Example 1 Low-density polyethylene ("Mirason 12" manufactured by Mitsui Petrochemical Industries, Ltd.) forming the base material layer and ethylene-vinyl acetate copolymer ("EVA25K" manufactured by Mitsubishi Yuka Co., Ltd.) forming the adhesive layer.
A mixture of 100 parts by weight of ``vinyl acetate content 11% by weight'' and 0.1 parts by weight of a powdered nonionic surfactant (``Electro Stripper TS-3'' manufactured by Kao Corporation) was prepared, with the former having a thickness of 40 μm and the latter having a thickness of 40 μm. so that the thickness is 20 μm,
A surface protection film was obtained by extrusion molding using a two-layer coextrusion method.

[0015] The obtained surface protection film was attached to a 2 mm thick polycarbonate plate (hereinafter abbreviated as PC board) using a laminator, left at 23°C for 30 minutes, and then peeled off with a peel width of 25 mm to determine the initial adhesive strength. was measured.

Similarly, after pasting on a PC board, it was placed in a hot air circulation oven preheated to 90°C and 160°C.
After being left for 0 minutes, it was taken out, cooled to room temperature, and peeled off with a peeling width of 25 mm to measure adhesive strength 1 and 2 after heat treatment.

Similarly, after pasting it on a PC board, the room temperature was 23°C.
After leaving it for 60 minutes in an atmosphere with a humidity of 30% RH, it was peeled off by hand (peeling speed of about 20 m/min) and 10 minutes from the PC board.
The electrostatic voltage was measured 5 seconds after peeling off at a point separated by cm.

[0018] Initial adhesive strength is 5.0 g/25 mm width, adhesive strength 1 after heat treatment is 300.0 g/25 mm width, adhesive strength 2 after heat treatment is 1000.0 g/25 mm width or more, and electrostatic voltage after peeling is +500 V. Met. Example 2 Surface protection was carried out as in Example 1 except that the antistatic agent added to the adhesive layer was replaced with a powdered nonionic surfactant (“Denon 331P” manufactured by Marubishi Yuka Kogyo Co., Ltd.). A film was obtained, and its adhesive strength and charging voltage were measured.

[0019] Initial adhesive strength is 4.5 g/25 mm width, adhesive strength 1 after heat treatment is 300.0 g/25 mm width, adhesive strength 2 after heat treatment is 1000.0 g/25 mm width or more, and electrostatic voltage after peeling is +950 V. Met. Example 3 The antistatic agent added to the adhesive layer was a powdered nonionic surfactant (“Denon 331P” manufactured by Marubishi Yuka Kogyo Co., Ltd.) 6.
A surface protective film was obtained in the same manner as in Example 1 except that the amount was changed to 0 parts by weight, and the adhesive force and charging voltage were measured.

[0020] Initial adhesive strength is 4.0 g/25 mm width, adhesive strength 1 after heat treatment is 300.0 g/25 mm width, adhesive strength 2 after heat treatment is 1000.0 g/25 mm width or more, and electrostatic voltage after peeling is +800 V. Met. Example 4 The antistatic agent added to the adhesive layer was a nonionic surfactant that is liquid at room temperature (“Denon 331L” manufactured by Marubishi Yuka Kogyo Co., Ltd.)
A surface protection film was obtained in the same manner as in Example 1 except that the adhesive force and charging voltage were measured.

[0021] The initial adhesive strength is 3.0 g/25 mm width, the adhesive strength 1 after heat treatment is 12.5 g/25 mm width, the adhesive strength 2 after heat treatment is 35.0 g/25 mm width, and the electrostatic voltage after peeling is +250 V. there were. Example 5 Nonionic surfactant of Example 4 (“Denon 331L”)
A surface protective film was obtained in the same manner as in Example 4, except that the amount of 6.0 parts by weight was added, and the adhesive strength and charging voltage were measured.

[0022] The initial adhesive strength is 1.0 g/25 mm width, the adhesive strength 1 after heat treatment is 6.5 g/25 mm width, the adhesive strength 2 after heat treatment is 14.0 g/25 mm width, and the electrostatic voltage after peeling is + 100 V. there were. Example 6 The same procedure as Example 4 was carried out, except that the ethylene-vinyl acetate copolymer forming the adhesive layer was replaced with linear low-density polyethylene ("Urtzex 2080C" manufactured by Mitsui Petrochemical Industries, Ltd.), and the surface was A protective film was obtained, and its adhesive strength and charging voltage were measured.

[0023] The initial adhesive strength is 1.0 g/25 mm width, the adhesive strength 1 after heat treatment is 4.0 g/25 mm width, the adhesive strength 2 after heat treatment is 9.0 g/25 mm width, and the electrostatic voltage after peeling is +250 V. there were. Example 7 The ethylene-vinyl acetate copolymer forming the adhesive layer was replaced with an ethylene-ethyl acrylate copolymer (“EVAFLEX-FEAA-703” manufactured by DuPont Mitsui Polychemicals Co., Ltd.)
A surface protection film was obtained in the same manner as in Example 4 except that the content of ethyl acrylate was 25% by weight).
Adhesive force and charging voltage were measured.

[0024] The initial adhesive force is 4.0 g/25 mm width, the adhesive force 1 after heat treatment is 11.0 g/25 mm width, the adhesive force 2 after heat treatment is 22.0 g/25 mm width, and the electrostatic voltage after peeling is +200 V. there were. Example 8 Example 4 except that the ethylene-vinyl acetate copolymer forming the adhesive layer was replaced with an ethylene-methyl methacrylate copolymer ("Acrift WH303" manufactured by Sumitomo Chemical Co., Ltd. Methyl methacrylate content: 18% by weight) A surface protective film was obtained as described above, and its adhesive strength and charging voltage were measured.

[0025] The initial adhesive strength is 3.5 g/25 mm width, the adhesive strength 1 after heat treatment is 10.5 g/25 mm width, the adhesive strength 2 after heat treatment is 19.0 g/25 mm width, and the charged voltage after peeling is +300 V. there were. Comparative Example 1 A surface protective film was obtained in the same manner as in Example 1, except that no antistatic agent was added to the adhesive layer, and the adhesive strength and charging voltage were measured.

[0026] Initial adhesive strength is 5.0 g/25 mm width, adhesive strength 1 after heat treatment is 300.0 g/25 mm width, adhesive strength 2 after heat treatment is 1000.0 g/25 mm width or more, and electrostatic voltage after peeling is +10000 V. Met. Comparative Example 2 No antistatic agent was added to the adhesive layer, and 100 parts by weight of low-density polyethylene to form the base layer was added with a nonionic surfactant (“Denon 331L” manufactured by Marubishi Yuka Kogyo Co., Ltd.) that is liquid at room temperature.
'') A surface protective film was obtained in the same manner as in Example 1 except that 0.1 part by weight was added, and the adhesive force and charging voltage were measured.

[0027] The initial adhesive strength is 4.5 g/25 mm width, the adhesive strength 1 after heat treatment is 300.0 g/25 mm width, the adhesive strength 2 after heat treatment is 1000.0 g/25 mm width or more, and the charged voltage after peeling is +7000 V. there were. Comparative Example 3 No antistatic agent was added to the adhesive layer, and 100 parts by weight of low-density polyethylene to form the base layer was added with a nonionic surfactant (“Denon 331L” manufactured by Marubishi Yuka Kogyo Co., Ltd.) that is liquid at room temperature.
A surface protective film was obtained in the same manner as in Example 1, except that 6.0 parts by weight was added, and the adhesive force and charging voltage were measured.

[0028] Initial adhesive strength is 4.0 g/25 mm width, adhesive strength 1 after heat treatment is 300.0 g/25 mm width, adhesive strength 2 after heat treatment is 1000.0 g/25 mm width or more, and electrostatic voltage after peeling is +5000 V. there were. The formulations and physical properties of the above Examples and Comparative Examples are summarized in Table 1.

[0029]

[Table 1]

As mentioned above, in Examples 1 to 8, the generation of static electricity was smaller than in Comparative Examples 1 to 3, respectively, especially in Examples 1 to 5 in which an antistatic agent that was liquid at room temperature was added. Even when heat treatment was applied to the synthetic resin plate after adhesion, the adhesive strength did not increase significantly.

[0031]

[Effects of the Invention] Since the surface protection film of the present invention is constructed as described above, even when it is peeled off after being attached to a highly insulating synthetic resin board, the electrostatic voltage can be kept low. Suitable for surface protection of synthetic resin plates.

[0032] Especially when an antistatic agent that is liquid at room temperature is added, even if the synthetic resin plate is subjected to secondary processing such as vacuum forming at high temperatures, the tendency of adhesion is small and it can be easily peeled off. .

Claims (2)

[Claims] 1. A surface protection film comprising an adhesive layer formed on one side of a thermoplastic resin film, characterized in that an antistatic agent is added to the adhesive layer. 2. The surface protection film according to claim 1, wherein the antistatic agent is liquid at room temperature.