JPS62214948A - Multilayer film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a multilayer film, and more particularly to a multilayer film that can be effectively used for packaging articles such as home appliances, office equipment, and furniture.

[Prior art and problems to be solved by the invention] Conventionally, packaging of items such as home appliances such as televisions and audio equipment, office equipment, precision equipment, and furniture has been done to prevent scratches and damage to these items. To do this, the article is usually packaged in advance with a film such as polyethylene, then fixed with cushioning material such as resin foam or corrugated poles, and then placed in an exterior case. However, in this case, there is a problem that the protection of the article is not sufficient due to friction between the film and the article, resulting in scratches, peeling of the paint, etc.

For this reason, it has been proposed to use a laminated film made by laminating a foamed low-density polyethylene film and an unfoamed polyethylene film, or a low-density polyethylene coextruded multilayer film consisting of a foamed layer and a non-foamed layer, as these packaging films. ing.

However, the former laminate film has a high processing cost, and it is virtually difficult to produce a thin foamed film, so the thickness must be within the range of thickness, and the strength is low compared to the film thickness. The disadvantage is that the packaging cost is high. In addition, in the case of the latter multilayer film, since the resin used is the same, the intermediate layer is a foam layer, which provides cushioning properties, and when compared with the same weight φ film, it has characteristics such as stiffness. However, in terms of friction with the packaged goods and cushioning material, it is no different from a single-layer film, and there is a problem in that the protection of the goods is not measured.

It is an object of the present invention to solve the above-mentioned conventional problems, and to provide a multilayer film that can provide additional protection to packaged articles, is easy to manufacture, and has high strength.

[Means for Solving Problems J] That is, the present invention is a cylindrical coextruded multilayer film in which the intermediate layer is made of a foamed resin layer and both outer layers are made of non-foamed resin layers, and one of the outer layers is made of a non-foamed resin layer. The object of the present invention is to provide a multilayer film characterized in that one layer is slippery and the other layer is easily slippery.

Although various thermoplastic resins can be used as raw materials for the multilayer film of the present invention, polyolefin resins are usually used. Here, as polyolefin resin,
In addition to polyethylene resins, examples include polypropylene, polybutene, and mixtures thereof. Any known polyethylene resin can be used as the above-mentioned polyethylene resin, such as high-density polyethylene (HOPE
).

Examples include medium density polyethylene (MDPE), low density polyethylene (LDPE), etc. In addition to ethylene homopolymers, ethylene-ethyl acrylate copolymers, ethylene-vinyl acetate copolymers (vinyl acetate content 10% by weight or less), Random or block copolymers such as low-crystalline ethylene-α-olefin copolymers and ethylene-unsaturated carboxylic acid copolymers, or mixtures thereof are available. Here, high density polyethylene has a density of 0.94
0~0.970g/, cm3, melt index (
XI) 0.01-10g/10min, preferably 0.0
It is 2-5 g/10 minutes. Medium- and low-density polyethylenes include high-pressure polyethylene and copolymers of ethylene obtained by medium- and low-pressure processes with α-olefins having 3 to 12 carbon atoms, such as propylene, butene-1,4-methylpentene-1, and octene-1. There is so-called linear low-density polyethylene (LLDPE), where medium-low density polyethylene has a density of 0.900 to 0.940 g/cm3,
Nl O, 1 to 50 g/10 min, preferably 0.2 to
20g/10 minutes. In addition, low crystalline ethylene-α-
As an olefin copolymer, the density is 0.900g/cm3
The following ethylene-propylene copolymer (EPR),
Ethylene-propylene-diene copolymer (EPDM)
, ethylene-butene-1 octapolymer, and the like.

The multilayer film of the present invention is obtained by coextrusion inflation molding the above-mentioned raw material resins, and has an intermediate layer made of a foamed resin layer and both outer layers made of non-foamed resin layers. Although the raw material resin constituting the intermediate layer is not particularly limited, it is preferable to use a polyethylene resin, particularly a low-density polyethylene resin as a main component.

Furthermore, the foaming agents that can be used to form the intermediate foamed resin layer can be broadly classified into chemical foaming agents and physical foaming agents based on their foaming mechanism. Among these, chemical blowing agents include:
Examples include azodicarbonamide, dinitropentamethylenetetramine, azodiisobutyronitrile, and physical blowing agents include butane, hebutane, hexane, dichlorodifluoromethane, nitrogen, carbon dioxide, and the like.

In this foamed resin layer, the blending ratio of the raw resin and the foaming agent is not particularly limited and varies depending on the type of foaming agent, etc., but in short, the foaming ratio is 1.2 to 5.0, preferably 1.2 to 4.0.
All you have to do is set it so that

In addition to a nucleating agent 1 coloring agent such as non-aluminum fine powder, rubbers, carboxylic ugly metal salts, etc. can be added to this foamed resin layer as appropriate.

Next, both outer layers of the multilayer film of the present invention are made of non-foamed resin layers, and one is made to be non-slip and the other is easy to slip. Here, non-slip property means that the coefficient of static friction of the surface is 0.4 or more, preferably 0.45 or more. In this case, the static friction coefficient refers to the static friction coefficient between two layers of the same type. On the other hand, slipperiness means that the coefficient of static friction on the surface is less than 0.4, preferably 0.35 or less. In the present invention, the difference in the coefficient of static friction between the surfaces of both outer layers is 0.1. The above is preferable, however, the static friction coefficient of the surfaces of both outer layers should be determined in consideration of moldability and the like.

The raw resin constituting the non-foamed resin layer may be appropriately selected from the thermoplastic resins mentioned above, but in particular, the non-slip layer may be made mainly of low-density polyethylene, ethylene-vinyl acetate copolymer, etc. Preferably, the slippery layer is especially high density polyethylene.

In the present invention, a material mainly composed of polypropylene or the like is preferred.In the present invention, a difference in the coefficient of static friction may be created by selecting the raw resin as described above, or a difference in the coefficient of static friction may be created by adding a lubricant.

There are various types of lubricants; for example, fatty acid lubricants such as higher fatty acids and oxyfatty acids; fatty acid amide lubricants such as fatty acid amide; fatty acid ester lubricants;
Hydrocarbon-based lubricants include alcohol-based lubricants. Note that it is preferable to add antistatic agents such as various surfactants to this non-foamed resin layer.

The multilayer film of the present invention has the above-mentioned structure, and usually consists of a three-layer film including an intermediate layer and both outer layers. Here, one of the two outer layers is defined as outer layer (A) and the other as outer layer (B), and the layer ratio is outer layer (A): intermediate layer: outer layer (B).
), it is preferably 5-60:lO-80:5-60. In addition, the thickness of the multilayer film is usually 20
~200p. Although the multilayer film of the present invention is a cylindrical coextruded multilayer film, it can also be opened to form a flat film. In the present invention, the slippery layer is usually formed on the inside of the cylindrical film.

Such a multilayer film of the present invention can be produced by coextrusion inflation molding the raw material resin using a conventional extrusion molding machine. Specifically, the above-mentioned raw resins were melt-kneaded using respective extruders, and then co-extruded with a foamed resin layer as an intermediate layer and non-foamed resin layers as both outer layers, and further with a blowing ratio of 1.5.
Inflation molding may be performed in steps 5 to 5. Incidentally, the gouly temperature at this time is usually 130 to 180°C, and the gouly lip gap is usually 0.5 to 2 tw.

[Effects of the Invention] Since the multilayer film of the present invention has different coefficients of static friction on the surfaces of both outer layers, when used as a packaging film, there is little slippage against the packaged article, and moreover, it easily slips against external cushioning materials, etc. It has become. Therefore, the packaged articles can be effectively protected without damaging the packaged articles or peeling off the coating due to friction between the film and the packaged articles.

Moreover, since the multilayer film of the present invention has a foamed resin layer as an intermediate layer, the foaming efficiency is high, and there is no occurrence of so-called eye stain, so that production is easy.

Furthermore, the multilayer film of the present invention can be made thin and has sufficient strength even as a thin film. Therefore, packaging costs can be reduced and resources can be saved.

Furthermore, the multilayer film of the present invention has good surface printability, and has a luxurious appearance with a pearl-like luster and a Japanese paper feel.

Therefore, 1. The multilayer film of the present invention can be used for home appliances, office equipment,
It can be effectively used for packaging various items such as furniture.

[Example] Next, examples of the present invention will be shown.

Examples 1 to 4 The resins shown in Table 1 were melt-kneaded using an extrusion molding machine made by Ohdai, and then introduced into a circular gouie with adhesive inside the gou, extruded, and then inflation molded at a blow ratio of 3 to form a predetermined layer ratio. A three-layer film with a pearl-like luster and having a foamed resin layer in the middle was obtained. Table 1 shows the results of measuring the physical properties of this film. The film thickness when the intermediate layer is not foamed is 60.
It was le. Further, 4% by weight of azodicarbonamide was added as a foaming agent to the intermediate layer.

Reference Example Table 1 shows the results of measuring the physical properties of a commercially available laminate film (a laminate film of a foamed low-density polyethylene film with a thickness of 500 IL and a high-density polyethylene with a thickness of 13P).

Low HDPE: Made by Idemitsu Petrochemical ■, Idemitsu Polyethylene 8
400F, density 0.950g813XI O,0
3g/10min LDPE-A: manufactured by Toyo Soda Kogyo ■, Petrosen 205
゜Density 0.924g/cm3, Ml 3g/10min LDPE-B: Toyo Soda Kogyo ■, Petrocene 175
゜Density 0.921g/cm3. MI O, 13g/1
0 minute LLDPE-1: Manufactured by Idemitsu Petrochemical ■, Moretic 0
138N, density 0.920g/cm3, Ml
g/10 min LLDPE II: Manufactured by Idemitsu Petrochemical ■, Idemitsu Polyethylene-L 0134L, density 0.920 g/
cm3.

XI 1 g/10 min LL [lPE-m: manufactured by Idemitsu Petrochemical Company, Idemitsu Polyethylene-L 0234H, density 0.920 g/cs3.

Claims (1)

[Scope of Claims] 1. A cylindrical coextruded multilayer film in which the middle layer is made of a foamed resin layer and both outer layers are made of non-foamed resin layers, one of the two outer layers is non-slip and the other is non-slip. A multilayer film characterized by easy slipping. 2. The multilayer film according to claim 1, wherein the resin is a polyolefin resin.