JPH08276485A - Production of surface protecting film - Google Patents

Abstract

PURPOSE: To produce a surface protecting film by extruding a cylindrical film so that the innermost layer is set to a self-adhesive layer by a multilayered co-extrusion inflation molding method without generating trouble in a molding process and taking over the same while turning the self-adhesive layer inwardly to protect the same. CONSTITUTION: A base material layer with a total thickness of 30-200μm of which at least the inner surface of a thermoplastic resin compsn. obtained by adding 0.1-12 pts.wt. of an inorg. filler to 100 pts.wt. of a thermopastic resin and a self-adhesive layer with a thickness of 20μm or less are extruded from a multilayered extrusion circular die so that the self-adhesive layer becomes inside to form a cylindrical multilayered film. After the surface temp. of the cylindrical multilayered film is cooled to 50 deg.C, the film is folded to be taken over.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a surface protective film.

[0002]

2. Description of the Related Art Conventionally, when a surface protective film is formed by using a multi-layer coextrusion circular die, when the tubular film is folded in a pinch roll part, the adhesive layers of the tubular film are blocked to obtain a film. Reopen the tubular film that has been opened to avoid being unable to be processed into one or more surface protection films,
In general, a tubular film having a substrate layer inside and an adhesive layer outside has been formed.

However, when the tubular film is formed by the inflation method with the adhesive layer on the outside, dust or other foreign matter may be attached to the adhesive layer during the molding process and the semi-finished product and product conveying process, and the inflation molding may be performed. Due to the large frictional resistance in the various guide rolls of the machine, lumps and wrinkles occur when winding semi-finished products and products, and if this is significant, the tubular film being formed will wind around the guide rolls. There is a possibility that troubles such as interrupting the molding process may occur. Although various attempts have been made to reduce the frictional resistance of each portion of the inflation molding apparatus that comes into contact with the above-mentioned tubular film, a sufficient measure for solving the above problems has not yet been devised.

JP-A-3-125139 discloses that the innermost layer has a low polymerization degree of polyolefin resin of 0.05 to 10% by weight.
And tackifier 0.05 to 10% by weight and antioxidant 0.0
A packaging material comprising a multi-layer coextrusion inflation film made of a thermoplastic resin composition containing 1 to 0.8% by weight, and comprising a laminated film in which innermost layers of the inflation film are adhered by blocking. It is disclosed.

However, the above-mentioned packaging material is configured to form a layer having adhesiveness on the inner side when forming a multi-layer coextrusion blown film, but the above technique does not form a tubular film. The present invention relates to a technique for forming a laminated film in which the innermost layers having the above-mentioned adhesiveness are pseudo-adhered by blocking. By stopping the pseudo-adhesive state in this way, it is possible to improve the hardness of a laminated film in which two layers of uniaxially stretched film disclosed in JP-A-57-6754 are laminated with an adhesive, for example. The effect is described.

The technique disclosed in JP-A-3-125139 is a technique in which the innermost layers of a multi-layer coextrusion blown film are positively blocked. At this point, the innermost layer is an adhesive layer. In that case, blocking could not be avoided by the multilayer coextrusion inflation method.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above facts, and an object thereof is to adhere the innermost layer to the innermost layer without trouble in the molding step by a multi-layer coextrusion inflation molding method. It is another object of the present invention to provide a method for producing a surface protective film in which a tubular film is extruded as a layer, and the pressure-sensitive adhesive layer is taken out while protecting it as an inner layer.

[0008]

According to the present invention, at least the inner surface is made of a thermoplastic resin composition containing 0.1 to 12 parts by weight of an inorganic filler with respect to 100 parts by weight of the thermoplastic resin. A substrate layer having a thickness of 30 to 200 μm and an adhesive layer having a thickness of 20 μm or less are extruded into a tubular shape with the adhesive layer inside from a multilayer coextrusion circular die, and the surface temperature of the tubular multilayer film is 50 ° C. or less. The gist of the invention is a method for producing a surface protective film, which is characterized in that it is cooled and then folded and taken out.

The thermoplastic resin used in the present invention is applied to the surface of a synthetic resin plate such as a vinyl chloride resin plate, an acrylic resin plate, a polycarbonate resin plate, a surface-treated steel plate, a metal plate such as a surface-treated aluminum plate, or the like. It is not particularly limited as long as it can be attached and protect the surface of the protected object during process movement or processing, for example,
Mainly composed of polymers and copolymers of mono-olefins such as ethylene, propylene and butene, for example, high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, polypropylene, ethylene-propylene block Examples thereof include copolymers, ethylene-propylene random copolymers, polybutene-1, and polymethylpentene-1. The structure may be a single layer or multiple layers.

The above-mentioned inorganic filler is contained in at least the innermost surface of the base material layer, not the adhesive layer, in an amount of 0.1 to 12 parts by weight based on 100 parts by weight of the thermoplastic resin. If limited, the type is not particularly limited, and examples thereof include titanium oxide, zinc oxide,
Examples include precipitated barium sulfate, silica, alumina, kaolin, clay, diatomaceous earth, calcium carbonate, mica, talc and the like.

If the amount of the above-mentioned inorganic filler added is less than 0.1 parts by weight, the effect of inhibiting the adhesion of the adhesive layer will not be sufficiently exerted, and if it exceeds 12 parts by weight, the unevenness of the surface of the adhesive layer will become large, which is sufficient. I can't get good adhesion.

The thickness of the base material layer depends on the purpose of protecting the object to be protected, but it is attached to the surface of a synthetic resin plate or a surface-treated metal plate, and its movement, surface protection during storage, bending or 30 μm when used for surface protection during processing such as cutting
If it is less than 200 μm, a sufficient protective effect cannot be obtained, and if it exceeds 200 μm, the surface cannot be protected by following the object to be protected during the bending process.

The pressure-sensitive adhesive layer is appropriately selected and used depending on the properties of the thermoplastic resin used for the base material layer. For example, when an olefin resin is used for the base material layer, SE is used.
Block copolymers such as BS and SIS, EVA and the like are preferably used.

The thickness of the pressure-sensitive adhesive layer must be 20 μm or less, and if it exceeds 20 μm, the effect of adding the inorganic filler to the base material layer is impaired, and the pressure-sensitive adhesive layers adhere to each other to form a folded tubular film. Cannot be peeled off.

The base material layer and the adhesive layer are extruded in a tubular shape from the multilayer coextrusion circular die with the adhesive layer inside and cooled from the outer periphery of the tubular multilayer film.
It is not particularly limited as long as it can be cooled evenly and efficiently over the entire circumference of the tubular multilayer film, and an air ring in which a cooling means of a refrigerant or the like is optionally combined is preferably used. Surface temperature of 5
After cooling to 0 ° C. or lower, it is folded by a pinch roll and taken out. The surface temperature of the tubular multilayer film is 5
When it is folded by a pinch roll at a temperature above 0 ° C., the tubular multilayer film adheres to the adhesive layer and becomes difficult to peel off.

If necessary, an ultraviolet absorber, a flame retardant, an antistatic agent, a lubricant, a coloring agent and the like may be added to the base material layer and the adhesive layer.

[0017]

In the method for producing a surface protective film of the present invention, at least the inner surface is made of a thermoplastic resin composition containing 0.1 to 12 parts by weight of an inorganic filler with respect to 100 parts by weight of the thermoplastic resin, and A substrate layer having a total thickness of 30 to 200 μm and an adhesive layer having a thickness of 20 μm or less are extruded in a tubular shape with the adhesive layer inside from a multilayer coextrusion circular die, and the surface temperature of the tubular multilayer film is 50 ° C. After cooling to
Since it is folded and taken up, the inorganic filler imparts appropriate unevenness to the surface of the adhesive layer to inhibit its adhesion and is folded after the adhesive layer has been sufficiently cooled, and the tubular film is, for example, both sides. Since it does not come into direct contact with the manufacturing equipment at all until it is cut open at the end and wound up as two surface protective films on the core, the adhesive layer may reduce the adhesive strength due to dust in the air and other foreign matter. The appearance is not impaired, and there is no risk of large frictional resistance, wrinkles in the contact portion, or winding around the rotating portion of the manufacturing apparatus.

Further, since the base material layer is on the outer side, a release layer provided on the base material layer can be carried out in the inflation molding step, if necessary, and after the release processing is performed, the tubular film is formed, for example. Since it is possible to cut open at both ends to form two surface protection films, the surface protection film can be efficiently produced without being contaminated.

[0019]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 A resin composition obtained by adding 3 parts by weight of titanium oxide to 100 parts by weight of low-density polyethylene (trade name: LK30, manufactured by Mitsubishi Chemical Co., Ltd.) is used as a base material layer to have a thickness of 100 μm. In addition, a two-layer coextrusion inflation method with an ethylene-vinyl acetate copolymer (manufactured by Mitsui DuPont Co., Ltd., trade name: Evaflex 260) as an adhesive layer to a thickness of 10 μm and with the adhesive layer inside After being extruded in a tubular shape by, the surface temperature of the tubular film was cooled to 40 ° C. around the tubular film, it was folded by a pinch roll, and taken out to prepare a surface protective film.

Example 2 A surface protective film was prepared in the same manner as in Example 1 except that 3 parts by weight of silica was used instead of 3 parts by weight of titanium oxide in Example 1.

(Example 3) The same procedure as in Example 1 was repeated except that a SEPS-based adhesive (Kuraray Co., Ltd., trade name: Septon G1657) was used in place of the ethylene-vinyl acetate copolymer of Example 1. To produce a surface protection film.

(Example 4) In place of the SEPS-based adhesive of Example 3, 100 parts by weight of the SEPS-based adhesive was added to a tackifying resin (Arakawa Chemical Co., Ltd., trade name: Alcon P10).
0) A surface protective film was produced in the same manner as in Example 1 except that an adhesive containing 10 parts by weight was used.

Comparative Example 1 A surface protective film was produced in the same manner as in Example 1 except that titanium oxide was not added to the low density polyethylene of Example 1.

(Comparative Example 2) The thickness of the adhesive layer of Comparative Example 1 was set to 1
A surface protective film was produced in the same manner as in Example 1 except that the thickness was changed from 0 μm to 40 μm.

(Comparative Example 3) The cooling conditions of Example 1, that is,
A surface protective film was produced in the same manner as in Example 1 except that the tubular film was folded with a pinch roll and the surface temperature of the tubular film before being taken out was changed from 40 ° C to 70 ° C.

Comparative Example 4 A surface protective film was prepared in the same manner as in Example 1 except that the positions of the base material layer and the adhesive layer in Comparative Example 1 were changed so that the adhesive layer was the outer layer of the tubular film. It was made.

Performance Test The surface protection films obtained in the above Examples and Comparative Examples were measured for the following items by the following test methods. Table 1 shows the test results.

1. Initial Adhesion Strength A surface protection film is attached to a 2 mm SUS plate with a laminator, and this is left for 30 minutes in an environment of a temperature of 23 ° C. and a humidity of 65% RH, and then a peeling width is 25 mm and a pulling speed is 300.
The initial adhesion was measured by a 180 degree peel test at mm / min.

2. Peeling force The peeling force was measured when the surface protective film wound on a 3-inch winding core was rewound at a peeling width of 25 mm and a pulling speed of 300 mm / min.

3. Contamination In the above Examples and Comparative Examples, visually inspecting for dust or other foreign matter when wound on a 3-inch winding core, ◯: substantially no adhesion, Δ: slightly adhesion, X: extremely adhesion not usable. The grade was evaluated.

4. In the above-mentioned Examples and Comparative Examples, by visually observing the wrinkle state of the tubular film after being folded with a pinch roll,
Evaluation was made in 3 grades: ◯: substantially no wrinkle, Δ: slightly wrinkled, and x: significantly wrinkled.

[0033]

[Table 1]

[0034]

EFFECTS OF THE INVENTION Since the method for producing a surface protective film of the present invention is configured as described above, it is folded after the adhesive layer is sufficiently cooled, and the tubular film is cut open at both ends, for example. Since it does not come into direct contact with the manufacturing equipment at all until it is wound onto the core as two surface protection films, dust and other foreign matter in the air may adhere to the adhesive layer, reducing the adhesive strength and impairing the appearance. In addition, there is no possibility that the frictional resistance is large and wrinkles are formed at the contact portion, or that the contact portion is wound around the rotating portion of the manufacturing apparatus.

Further, since the base material layer is on the outside, a release layer provided on the base material layer can be carried out during the inflation molding process as required, and after the release treatment is performed, the tubular film is treated with, for example, Since it is possible to cut open at both ends to form two surface protection films, the surface protection film can be efficiently produced without being contaminated.

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Claims (1)

[Claims] 1. A thermoplastic resin 100 having at least an inner surface.
It is made of a thermoplastic resin composition containing 0.1 to 12 parts by weight of an inorganic filler, and has a total thickness of 30 to 30 parts by weight.
A substrate layer having a thickness of 200 μm and an adhesive layer having a thickness of 20 μm or less are extruded into a tubular shape with the adhesive layer inside from a multilayer coextrusion circular die, and the surface temperature of the tubular multilayer film is 50
A method for producing a surface protective film, which comprises cooling after cooling to ℃ or below, and then folding and picking it up.