JPH0834098A - Composite film for dustless packing - Google Patents

Abstract

PURPOSE:To provide a composite film for dustless packing not blowing off foreign matter and suitable for packing an electronic machinery member such as a hard disk requiring clean packing free from dust and a contaminant. CONSTITUTION:A polyolefin resin layer to which a thermoplastic elastomer is added is laminated to both surfaces of a core layer being a polyamide resin layer and/or a saponified ethylene/vinyl acetate copolymer layer. By this constitution, a composite not blowing off foreign matter even when preserved for a long period of time and excellent in pinhole resistance and blocking resistance is obtained and can be suitably used in the packing of an electronic machinery member such as a hard disk requiring clean packing free from dust or a contaminant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite film, and more particularly, to a composite film for dust-free packaging which can be suitably used for packaging electronic equipment members such as hard disks which require clean packaging free from dust and contaminants. Regarding

[0002]

2. Description of the Related Art Usually, a bag-manufactured product made of a composite film having various resin layers has a slipperiness on the film surface to improve workability and an anti-blocking property to improve opening property of the film. It has been granted. In order to impart such slipperiness and antiblocking properties, it has been made to add a lubricant such as a fatty acid amide or an antiblocking agent such as an inorganic filler to the outermost layer or the innermost layer of the composite film.

However, there is a problem that the above lubricant easily blows out (bleeds out) on the surface of the film with the passage of time, and the blown product adheres to a packaged electronic device member such as a hard disk to cause a trouble. . Similarly, the antiblocking agent also has a problem that it is scraped from the film surface by the package and adheres to the package as a foreign substance.

[0004]

DISCLOSURE OF THE INVENTION The present invention has found a composite film which can solve the above problems, and its gist is to provide a polyamide resin layer and / or ethylene-
A composite film for dust-free packaging, comprising a saponified vinyl acetate copolymer layer as a core layer, and a polyolefin resin layer formed by adding a thermoplastic elastomer to both sides of the core layer.

In the composite film of the present invention, the polyamide resin layer and / or the saponified ethylene-vinyl acetate copolymer layer serves as the core layer, but the polyamide resin layer (hereinafter referred to as "P
"A") is for imparting pinhole resistance, and as the polyamide resin, nylon 6, nylon 66, a copolymer of nylon 6 and nylon 66, or the like can be used. The saponified ethylene-vinyl acetate copolymer layer (hereinafter, referred to as “EVOH”) may be provided when the barrier property is provided, and it is possible to prevent rust from occurring in the package.
EVOH with an ethylene content of 30 to 60 mol%
It is preferable that the saponification degree is 95% or more from the viewpoint of moldability and barrier properties.

It is necessary to laminate a polyolefin resin layer formed by adding a thermoplastic elastomer on both sides of the core layer, and the resin used for the polyolefin resin layer is a low density polyethylene resin (hereinafter referred to as "LDPE"). , Linear low-density polyethylene resin (hereinafter referred to as "LLDP
"E"), ultra-low density polyethylene resin (hereinafter "V"
LDPE ") and ethylene-vinyl acetate copolymer resin (hereinafter referred to as" EVA ") are preferable from the viewpoint of moisture permeability and heat sealability.

Here, a thermoplastic elastomer is mixed in the polyolefin resin layer. As the thermoplastic elastomer, a hydrogenated product of styrene-butadiene-styrene block copolymer (SEBS) or styrene-isoprene-styrene block copolymer is used. Polyolefin-based thermoplastic elastomers such as polymer hydrogenated products (SEPS), block copolymers of these with styrene, and ethylene-α-olefin random copolymers can be preferably used. This thermoplastic elastomer is preferably added in the range of 3 to 30 parts by weight with respect to 100 parts by weight of the polyolefin resin,
If the amount is less than 3 parts by weight, the inner surfaces of the bag-making product are likely to block each other, resulting in poor blocking resistance, and if the amount exceeds 30 parts by weight, the pinhole resistance tends to be poor.

A polyolefin-based adhesive resin layer (hereinafter referred to as "PO contact") may be interposed between the core layer and the polyolefin resin layer to increase the adhesive force between the two layers. An acid-modified polyolefin resin grafted with at least one monomer selected from unsaturated carboxylic acids or derivatives thereof can be preferably used. The composite film having the above structure may be formed into a film by various manufacturing methods, and a method by a coextrusion molding method is preferable from the viewpoint of productivity and adhesiveness between layers.

The present invention will be described below with reference to examples.

[0010]

【Example】

Example 1 Layer structure: Outermost layer (first layer): 100 parts by weight of LDPE was added to an olefinic thermoplastic elastomer (Milastomer 503).
0N Mitsui Petrochemical (manufactured)) 5 layers by weight, second layer: carboxylic acid-modified ethylene-vinyl acetate copolymer (PO contact), third layer: nylon 6, fourth layer: carboxylic acid-modified ethylene -Vinyl acetate copolymer (in contact with PO), 5th layer (seal layer): a structure in which 5 parts by weight of an olefinic thermoplastic elastomer (same as above) is added to 100 parts by weight of LDPE.

Thickness: First layer / PO contact / nylon 6 / PO contact / fifth layer (20 μm / 5 μm / 20 μm / 5 μm / 40 μ
m) The composite film having the above structure was coextruded to form a film in a cylindrical shape by an inflation molding method. Using the obtained composite film, "foreign matter blowing property" and "blocking prevention property"
And "pinhole resistance" were evaluated.

The "foreign matter blowing property" was as follows. The above composite film was stored for one month in an atmosphere of 23 ° C and 65% relative humidity, and was inspected for foreign matter blowing. "Anti-blocking property" is 1kg / cm ^{2 for} a cylindrical composite film.
After the pressure was applied for 1 day and the film was stored for 1 day, the ease with which the opening of the film was opened was examined. Further, regarding the “pinhole resistance”, a gelbo flex test was performed in an atmosphere of 23 ° C. and 65% relative humidity, and the number of pinholes generated by bending 5000 times was counted. When evaluated by the above method,
No foreign matter was blown out, the opening was opened well, pinholes were not generated, and the pinhole resistance was also good.

Example 2 Layer structure: Outermost layer (first layer): Layer in which 30 parts by weight of olefinic thermoplastic elastomer was added to 100 parts by weight of LLDPE, Second layer: Carboxylic acid-modified ethylene-vinyl acetate copolymer (PO) Contact), the third layer: nylon 6, the fourth layer: carboxylic acid-modified ethylene-vinyl acetate copolymer (contact with PO),
Fifth layer (seal layer): a structure in which 30 parts by weight of an olefinic thermoplastic elastomer is added to 100 parts by weight of EVA. Thickness: 1st layer / PO contact / Nylon 6 / PO contact / 5th layer (20 μm / 5 μm / 20 μm / 5 μm / 40 μ
m) The composite film having the above structure was coextruded to form a film in a cylindrical shape by an inflation molding method. Using the obtained composite film, "foreign matter blowing property" and "blocking prevention property"
And "pinhole resistance" were evaluated. as a result,
As in Example 1, there was no problem in any of the items.

Example 3 Except that the first layer was a layer in which 2 parts by weight of an olefinic thermoplastic elastomer was added to 100 parts by weight of LDPE, and the fifth layer was a layer in which 2 parts by weight of an olefinic thermoplastic elastomer was added to 100 parts by weight. When a composite film having the same content as in Example 1 was obtained and evaluated, no foreign matter was blown out or pinholes were not generated, but the cylindrical film tended to be slightly open due to blocking.

Example 4 The first layer was a layer in which 35 parts by weight of an olefinic thermoplastic elastomer was added to 100 parts by weight of LDPE, and the fifth layer was 100 parts.
A composite film was obtained and evaluated in the same manner as in Example 1, except that 35 parts by weight of the olefinic thermoplastic elastomer was added to the parts by weight, and no evaluation was made that no foreign matter was blown out or blocking occurred. 3 occurred and the pinhole resistance was poor.

Comparative Example 1 The first layer was LDPE with 0.04% by weight of oleic acid amide.
And the same content as in Example 1 except that the fifth layer is a layer in which 0.04% by weight of oleic acid amide and 0.05% of silicon oxide are added to EVA. When the composite film was obtained and evaluated, no pinholes were found, but it was difficult to open the cylindrical film due to blocking, and foreign matter was slightly blown out, which was a problem for dust-free packaging. .

[0017]

As described above, according to the composite film of the present invention, no foreign matter is blown out even when it is stored for a long period of time, and the pinhole resistance and blocking prevention are excellent.
It can be suitably used for packaging electronic equipment members such as hard disks that require clean packaging free of dust and contaminants.

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Claims (2)

[Claims] 1. A polyamide resin layer and / or ethylene-
A composite film for dust-free packaging, comprising a saponified vinyl acetate copolymer layer as a core layer, and a polyolefin resin layer formed by adding a thermoplastic elastomer to both sides of the core layer. 2. The polyolefin resin is selected from low-density polyethylene resin, linear low-density polyethylene resin, ultra-low-density polyethylene resin, and ethylene-vinyl acetate copolymer resin, and is thermoplastic to 100 parts by weight of the polyolefin resin. The composite film for dust-free packaging according to claim 1, wherein the elastomer is added in an amount of 3 to 30 parts by weight.