JPH08174751A - Packaging multilayer film and production thereof - Google Patents

Abstract

PURPOSE: To obtain a packaging multilayer film superior in gas barrier properties and light-shielding properties by a method wherein a resin composition layer having a good adhesion to a metallizing surface of a metallized polyropylene film and little deterioration of mechanical strength after processing is provided on the metallizing surface. CONSTITUTION: On a metallizing surface of a metallized polypropylene film, a resin composition layer is provided, which is composed of 5-30 pts.wt. ethylene/ ethylene unsatd. carboxylate copolymer and 95-70 pts.wt. ethylene/ethylene unsatd. carboxylic acid/ethylene unsatd. carboxylate copolymer, contains 1-10wt.% ethylene unsatd. carboxylic acid, and has a melt flow rate of 15-50dg/ min.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer film for packaging having one layer of metallized polypropylene and a method for producing the same. More specifically, the present invention relates to an ethylene copolymer composition suitable for performing extrusion lamination, preferably sandwich lamination, on the metal-deposited surface side of a metal-deposited polypropylene film.

[0002]

2. Description of the Related Art At present, polypropylene (P
Various types of laminated films have been manufactured by extrusion laminating an olefin resin or the like to a metal vapor-deposited film obtained by vapor-depositing a metal such as aluminum on a plastic film such as P) or polyethylene terephthalate (PET). These films are widely used as packaging materials for foods and the like because of their excellent gas barrier properties and light-shielding properties and their metallic luster. Specifically, aluminum deposition PP
From two-layer and three-layer simple structures such as film / PP film and aluminum-deposited PP film / resin / PP film, to five-layer structure such as PP film / resin / aluminum-deposited PET film / resin / PP film And an anchor coat agent is used between layers as required.

In extrusion lamination, it is of course important to select a resin having excellent extrusion processability, but at the same time, it must have good adhesion to the metal deposition surface side. By the way, when extruding and laminating a resin onto a metal-deposited film, the adhesive strength of the metal-deposited layer to the film to be deposited tends to decrease immediately after processing or over time after processing due to heat history or shrinkage received during lamination. I have. The degree of occurrence of such a phenomenon varies depending on the type of the film to be deposited, and is not remarkable in a film having good heat resistance such as PET or nylon.
It is seen quite frequently in the case of P films. Therefore, in the case of extruding a resin on the metal-deposited surface side of a metal-deposited PP film, in order to obtain a laminated film having good interlayer adhesion, simply extruding a resin having good adhesiveness with metal into an extruded laminate. It is not necessary to use the resin, but it is necessary to consider a decrease in the adhesive strength between the PP film and the vapor-deposited metal, and selection of a suitable resin has never been easy.

To give a concrete example of problems, aluminum vapor deposition P
When a film having a constitution of P film / resin (A) / PP film coated with anchor coating agent is produced from the resin (A) by the sandwich extrusion laminating method, the resin (A) is used.
When an ethylene / ethylenically unsaturated carboxylic acid copolymer such as an ethylene / acrylic acid copolymer or an ethylene / methacrylic acid copolymer which is considered to have good adhesiveness to a metal is selected, the aluminum vapor-deposited PP is obtained immediately after processing. The film and the resin (A) have an appropriate peel strength. However, after about 3 to 10 days, a phenomenon in which the deposited aluminum layer and the PP film to be deposited are peeled off by a slight peeling force is recognized, and such a laminated film is not necessarily suitable for some applications. Absent.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and when extrusion lamination is performed on a metal-deposited PP film, a reduction in deposition strength after processing is small, and a good adhesive strength to a metal-deposited surface is provided. SUMMARY OF THE INVENTION An object of the present invention is to provide a novel multilayer film for packaging having a metallic luster excellent in gas barrier properties, light-shielding properties, and interlayer adhesion. Another object of the present invention is to provide a method for producing such a multilayer film by an extrusion laminating method which is economically advantageous.

[0006]

According to the present invention, an ethylene / ethylenically unsaturated carboxylic acid ester copolymer 5 is provided on the metal-deposited surface of a metal-deposited polypropylene film.
30 parts by weight, and an ethylene / ethylenically unsaturated carboxylic acid / ethylenically unsaturated carboxylic acid ester copolymer 95 to
70 parts by weight, having an ethylenically unsaturated carboxylic acid content of 1 to 10% by weight and a melt flow rate of 15 to 5%.
A multilayer film for packaging is provided, wherein a resin composition layer of 0 dg / min is formed. According to the present invention, there is also provided a method for producing the multilayer film for packaging, which comprises extrusion laminating the resin composition on the metal vapor deposition surface side of the metal vapor deposition polypropylene film.

In the present invention, the metal-deposited polypropylene film is a biaxially oriented polypropylene (OPP) or a non-oriented polypropylene film (CPP) on one or both sides of which a metal such as aluminum, copper, silver or gold is deposited by a known deposition method. A film deposited to a thickness of about 100 to 1000 °.

In the multilayer film for packaging of the present invention,
5-30 parts by weight of ethylene / ethylenically unsaturated carboxylic acid ester copolymer in contact with the metallized surface (at least one surface if formed on both surfaces) of the metallized polypropylene film and ethylene / ethylenically unsaturated Carboxylic acid / ethylenically unsaturated carboxylic acid ester copolymer 95
A resin composition layer consisting of about 70 parts by weight is formed.
As long as such a configuration is adopted, another layer may be further provided on one or both sides different from the contact surface between them.

Typical of the above ethylene / ethylenically unsaturated carboxylic acid ester copolymer is an ethylene / acrylic acid ester having an acrylic acid ester or methacrylic acid ester content of 5 to 50% by weight, preferably 15 to 50% by weight. Melt flow rate of copolymer and ethylene / methacrylic acid ester copolymer 1 to 100 dg / mi
n, preferably about 2 to 50 dg / min. The ester groups of the acrylates and methacrylates herein include methyl, ethyl, n-
Propyl, i-propyl, n-butyl, i-butyl, t-butyl, 2-ethylhexyl and the like.

The ethylene / ethylenically unsaturated carboxylic acid / ethylenically unsaturated carboxylic acid ester copolymer is typically a copolymer of ethylene / acrylic acid or methacrylic acid / acrylic acid ester or methacrylic acid ester. is there. Here, the acrylic acid ester or the methacrylic acid ester may be those as exemplified above. The ethylene content in the copolymer is 94-
30% by weight, preferably 80 to 40% by weight, the ethylenically unsaturated carboxylic acid content is usually 1 to 20% by weight, preferably 2 to 20% by weight, and the ethylenically unsaturated carboxylic acid ester content is usually 5 to 5%. ~ 50% by weight, preferably 15
~ 50% by weight. The melt flow rate is 1
About 100 dg / min, preferably 2 to 50 dg / min.
It is about min.

The amount of the ethylene / ethylenically unsaturated carboxylate copolymer is 5 to 30 parts by weight, preferably 10 to 30 parts by weight, depending on the type and composition of the above-mentioned copolymers.
Parts by weight of ethylene / ethylenically unsaturated carboxylic acid / ethylenically unsaturated carboxylic acid ester copolymer 95 to
70 parts by weight, preferably 90 to 70 parts by weight (total 100 parts by weight)
(Part by weight) is used. From the viewpoint of adhesiveness to metal-deposited polypropylene, the content of ethylenically unsaturated carboxylic acid in the resin composition is preferably 1-10.
%, Particularly preferably 2 to 8% by weight. If the amount is too small, the adhesion between the resin composition and the deposited metal surface tends to be inferior, and if the amount is too large, the adhesion between the deposited metal and the deposited polypropylene will be adversely affected, and in any case Also tends to peel easily. When the resin active material layer is formed on the metal-deposited polypropylene film by extrusion lamination, the melt flow rate of the resin composition is preferably 15 to 50 dg / min, and more preferably 20 to 50 in order to obtain good extrusion processability. It is good to be 35 dg / min. That is, if the melt flow rate is too small, the spreadability of the molten resin film is insufficient, and if it is too large, the neck-in (loss at both ends of the molten resin film) of the molten resin film becomes large.

The multilayer film for packaging according to the present invention can be produced by extrusion laminating the resin composition on a metal-deposited metal surface of a metal-deposited polypropylene film. Here, as extrusion lamination, in addition to simple lamination, multi-layer extrusion by co-extrusion lamination,
There is a two-time lamination by tandem lamination.
At this time, another thermoplastic resin film such as a biaxially stretched polypropylene film, an unstretched polypropylene film, a polyester, a polyamide, a low density polyethylene or the like is formed on the surface of the resin composition opposite to the surface in contact with the metal-deposited polypropylene film. It is possible to make a sandwich extrusion laminate by arranging. At this time, the laminate surface of another thermoplastic resin film may be coated with an anchor coat agent as necessary, or may be subjected to a corona treatment or the like. The thickness of the metallized polypropylene film or other thermoplastic film optionally formed is 10
About 100 μm is preferable, and the thickness of the resin composition layer to be extrusion-laminated is 5 to 200 μm, especially 10 to 5 μm.
It is preferably about 0 μ. The temperature of the extrusion lamination is preferably from 120 to 300C, particularly preferably from about 190 to 230C.

[0013]

According to the present invention, by extrusion lamination,
It is possible to provide a multilayer film for packaging having excellent interlayer adhesiveness and less decrease in interlayer adhesive strength with time. Such a multilayer film is suitable for packaging snack foods and the like that require moisture-proof properties and gas barrier properties.

[0014]

【Example】

Example 1 17% by weight of ethylene / ethyl acrylate copolymer (melt flow rate 6.0 dg / min, content of ethyl acrylate 41% by weight) as [A] component, ethylene / methacrylic acid as [B] component -Isobutyl acrylate copolymer (melt flow rate 36.9 dg / min,
A resin composition (melt flow rate 27.1) obtained by melt-blending 83% by weight of a methacrylic acid content of 10.0% and an isobutyl acrylate content of 10.0%) has a caliber of 65.
200 ° C resin temperature from T-die using extruder of mmφ
To form a molten thin film. Next, using a known extrusion laminating apparatus, the surface of the 25 μm-thick biaxially stretched polypropylene film (OPP) coated with an anchor coat (a commercially available imine-based anchor coating agent) and the 25 μm thick aluminum-deposited unstretched polypropylene film (CPP) were used. By extrusion coating the above-mentioned molten thin film between the aluminum deposition surfaces,
Aluminum laminated film with three layers (OPP25μm /
(AC agent) / Coating resin 15μm / Aluminum evaporation C
(PP 25 μm). The laminating speed is 80
m / min, the extrusion coating thickness was 15 μm (other processing conditions and the like are described below).

The three-layer aluminum-deposited laminated film obtained as described above was peeled between the coating resin and the aluminum-deposited CPP, and the interlayer adhesion was measured one day after and 30 days after the processing. Observation of the peeling interface was performed to confirm the presence or absence of peeling of the vapor-deposited aluminum from the CPP film. The extrusion laminating processability (drawdown property, neck-in property) of the above resin composition was also measured. The above-mentioned extrusion lamination processing conditions, measurement conditions, and the like are as follows.・ Extrusion lamination processing conditions -Adhesive force measurement conditions Peeling sample width: 15 m Peeling speed: 300 mm / min Peeling angle: 90 ° (T-type peeling) -Laminated workability measuring method Neck-in: Coat resin width and T-die opening when processed under the above-mentioned processing conditions Measure the difference from the width (500 mm). 60
There is no problem if it is less than mm. Drawdown property: resin extrusion amount under the above processing conditions (560
(g / min) The processing speed is gradually increased from 80 m / min while keeping it constant, and the processing speed at the time when the melt film breakage starts to be measured. It may be 140 m / min or more.

Examples 2 to 5 and Comparative Examples 1 to 7 The processing methods, conditions and the like of Examples 2 to 5 and Comparative Examples 1 to 7 were all the same as in Example 1 described above, and various extrusion coating processes were performed. It carried out about the resin composition. The composition of each resin composition is described below.

Example 2 8% by weight of an ethylene / ethyl acrylate copolymer (melt flow rate 25 dg / min, ethyl acrylate content 35% by weight) as the component [A], and the component [B] as in Example 1 A 92% by weight composition was used.

Example 3 As the component (A), 20% by weight of an ethylene / ethyl acrylate copolymer (melt flow rate: 5 dg / min, ethyl acrylate content: 25% by weight) was used. The same 80% by weight composition was used.

Comparative Example 1 Low-density polyethylene (melt flow rate 25 dg / m
in) was used.

Comparative Example 2 Ethylene / methacrylic acid copolymer (melt flow rate 25 dg / min, methacrylic acid content 10% by weight)
Was used.

Comparative Example 3 An ethylene / methacrylic acid / isobutyl acrylate terpolymer (melt flow rate 35 dg / min, methacrylic acid content 10% by weight, isobutyl acrylate content 10% by weight) was used.

Comparative Example 4 17% by weight of an ethylene / ethyl acrylate copolymer (melt flow rate: 8.0 dg / min, ethyl acrylate content: 41% by weight), an ethylene / methacrylic acid copolymer (melt flow rate: 35 dg) / Min, 10% by weight of methacrylic acid) was used.

Comparative Example 5 8% by weight of an ethylene / ethyl acrylate copolymer (melt flow rate 25 dg / min, ethyl acrylate content 35% by weight) as a component [A], and ethylene / methacrylic acid as a component [B] A composition comprising 92% by weight of an acid copolymer was used.

Comparative Example 6 Ethylene / vinyl acetate copolymer (melt flow rate 3
A composition comprising 20% by weight of 2 dg / min, vinyl acetate content of 33% by weight) and 80% by weight of ethylene / methacrylic acid copolymer (melt flow rate: 25 dg / min, methacrylic acid content: 15% by weight) is used. Was.

Comparative Example 7 Ethylene / methacrylic acid copolymer (melt flow rate 10.0 dg / min, methacrylic acid content 10% by weight) was 16% by weight and ethylene / methacrylic acid / isobutyl acrylate ternary copolymer. Coalescence (Melt flow rate 35
A composition comprising 84 wt% of dg / min, methacrylic acid content of 10 wt%, isobutyl acrylate content of 10 wt%) was used. Table 1 shows the evaluation results of the laminated films obtained in these Examples and Comparative Examples.

[0026]

[Table 1]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location B32B 31/30 9349-4F C08L 33/06 LJB (72) Inventor Yoshio Nozaki Yuuki Ichihara, Chiba Prefecture 1-1 Taito (72) Inventor Kenichi Date Ariaki Ichihara, Chiba 1-1 Taito 1-1

Claims (4)

[Claims] 1. An ethylene / ethylenically unsaturated carboxylic acid ester copolymer comprising 5 to 30 parts by weight of an ethylene / ethylenically unsaturated carboxylic acid ester copolymer on the metal deposition side of a metallized polypropylene film. A resin composition layer comprising 95 to 70 parts by weight of an ester copolymer, having an ethylenically unsaturated carboxylic acid content of 1 to 10% by weight and a melt flow rate of 15 to 50 dg / min is formed. And a multilayer film for packaging. 2. The multilayer film for packaging according to claim 1, wherein a stretched polypropylene film is further laminated in contact with the resin composition layer. 3. An ethylene / ethylenically unsaturated ester copolymer having 5 to 30 parts by weight of an ethylene / ethylenically unsaturated ester copolymer and an ethylene / ethylenically unsaturated carboxylic acid ester, Extrusion lamination of a resin composition comprising 95 to 70 parts by weight of a polymer, having an ethylenically unsaturated carboxylic acid content of 1 to 10% by weight and a melt flow rate of 15 to 50 dg / min. A method for producing a multilayer film. 4. The extruded laminate is a sandwich extruded laminate between a metallized surface of a metallized polypropylene film and a stretched polypropylene film.
The manufacturing method described.