JPS588984B2 - Curl-free gas barrier metallized laminate film and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, the inner layer is composed of a polyamide resin layer and a specific saponified ethylene-vinyl acetate copolymer layer, and the outer layer laminated on both outer surfaces of the inner layer is a hydrophobic thermoplastic resin layer. The present invention relates to a metal-deposited laminated film that does not curl, has excellent gas barrier properties, and has good impact resistance, and includes four metal-deposited layers.

Conventionally, gas barrier films are made from ethylene-vinyl acetate copolymers (with specific ethylene content and degree of saponification).
It is known that saponified materials (hereinafter abbreviated as "saponified materials") have particularly excellent effects.

However, films made solely of saponified materials have impact resistance,
; Since it is inferior in physical properties such as strength, and pinholes are likely to occur during use, it is often used by laminating it with other types of films to compensate for this drawback.

However, if other types of films are simply laminated, for example, if the outer layer is a saponified layer serving as a gas barrier layer, pinholes will still occur and the impact resistance will be poor.
This also caused problems during packaging.

Therefore, the present inventors focused on the excellent properties of polyamide-based resins, such as good gas barrier properties and impact resistance, and attempted to improve the above-mentioned drawbacks by laminating a polyamide-based film on a saponified material.

However, if this was done alone, the gas barrier properties would deteriorate due to co-absorption of moisture by both layers, and curling would occur due to the influence of temperature and humidity, causing trouble in the packaging process.

In addition, since this product has poor light-shielding properties, it is difficult to prevent photodeterioration of foods, etc., and there is a problem in using it for packaging long-term stored foods.

As a result of research based on these facts, the present inventors succeeded in establishing a new metal-deposited laminated film that overcomes all of the above-mentioned drawbacks, and a technology related to its manufacturing method.

That is, the present invention provides an inner layer consisting of two layers: a polyamide resin layer and a saponified ethylene-vinyl acetate copolymer layer with an ethylene content of 25 to 60 mol% and a saponification degree of 90% or more.
The outer layer laminated on one outer surface is a metal vapor-deposited layer, and the outer layer laminated on the other outer surface is a hydrophobic thermoplastic resin layer.It is a metal-deposited laminated film that does not curl. 3 consisting of a saponified moisture layer (A), a polyamide resin layer (B), and a hydrophobic thermoplastic layer (C)
This is a method for producing a metal-deposited film that does not curl, which is characterized by forming a laminated film and applying metal vapor deposition to the A side or B side of the film while maintaining a moisture-proof state. Regarding moisture-proofing, the film must have a volatile content (water vapor) of 1% or less, preferably 0.5% or less, and should not be exposed to temperatures and humidity that would produce more volatile water vapor. This is undesirable because the saponified material absorbs moisture, which causes uneven deposition, pinholes, and bubbles in the metal deposition process.

That is, if the saponified material enters the metal vapor deposition process in a state in which it has absorbed moisture, moisture, moisture evaporation, etc. will occur during the process, and the vapor deposition will be inhibited.

Regarding maintenance of the moisture-proof state, since the degree of moisture absorption of the saponified material is about 0.3 to 0.65% at 20°C x 80% RH x 24 hours, the moisture-proof state is maintained after film formation and winding, and the unwinding roll is used before metal vapor deposition. When attaching the saponified material, the moisture-proof state can be sufficiently maintained even if the moisture-proof state is removed, and the effects of the present invention can be fully achieved.

Further, the moisture-proof state can be maintained in a preferable state by packaging for moisture-proofing, but it goes without saying that other appropriate methods can be applied.

The saponified product according to the present invention has an ethylene content of 25 to 60
The saponified ethylene-vinyl acetate copolymer preferably has a mole % of 30 to 50 mole % and a saponification degree of 90% or more, preferably 95% or more.

Further, aluminum is suitable as the metal used for metal vapor deposition, but other metals such as tin and zinc can also be used.

Examples of the hydrophobic thermoplastic resin include polyolefin resins such as polyethylene, polypropylene and copolymers thereof, ionomer resins, and modified polyolefin resins having adhesive properties.

Particularly preferable modified polyolefin resins having adhesive properties include polyolefins such as polyethylene, polypropylene, and copolymers thereof, and at least one selected from unsaturated carboxylic acids such as fumaric acid and maleic acid, or derivatives thereof. ~10% by weight, preferably ~10-3
This is a modified polyolefin resin obtained by graft copolymerization in a range of 5% by weight.

Although well-known methods can be used to produce the three-layer film before metal vapor deposition according to the present invention, a particularly preferred method is a method of obtaining a three-layer film by coextrusion. Another example is a method in which a three-layer film is obtained by coextruding the saponified material layer and then melt-extrusion laminating the hydrophobic thermoplastic resin.

This three-layer film may be unstretched, uniaxially or biaxially stretched, or each layer may be unstretched, uniaxially or biaxially stretched.

The metal vapor-deposited laminated film of the present invention may be unstretched, but it can also be uniaxially or biaxially stretched, and a biaxially stretched film can also be used as a heat-shrinkable film.

Preferred embodiments included in the present invention include the following films.

This embodiment was made for the purpose of protecting the metal vapor deposited layer and further improving the physical properties of the film such as impact resistance.

(2) A metallized finolem formed by laminating a thermoplastic resin on the metallized surface of the film of the present invention via an adhesive layer.

In this case, examples of adhesive layers include various adhesive layers, layers of modified polyolefin resins having adhesive properties as described above, layers of ionomer resins, etc., and examples of thermoplastic resins include polyolefin resins such as polypropylene and polyethylene, and polychloride resins. Examples include vinyl, polyethylene terephthalate, etc.
This material may be unstretched, uniaxially or biaxially stretched.

A particularly preferred example is a method in which a modified polyolefin resin and/or an ionomer resin having adhesive properties and a polyolefin resin are coextruded and laminated on the metal vapor-deposited surface, and in this case, the metal vapor-deposited surface is subjected to wetting tension. Direct extrusion lamination is sufficiently possible at a pressure of about 40 dynes/cm2.

2) A metallized film obtained by melt-extruding and laminating the various resins mentioned above (especially preferably polyethylene) directly on the metallized surface of the film of the present invention.

At this time, the wetting tension of the metal vapor-deposited surface was approximately 40 dynes/cm.
2, and extrusion lamination is fully possible.

3) A metal vapor deposited film obtained by providing the metal vapor deposited film of the present invention with the vapor deposited protective layer of embodiment 1) or 2), and further extrusion laminating polyolefin such as polyethylene or polypropylene on the hydrophobic thermoplastic resin surface. .

In this case, it is particularly preferable to use the modified polyolefin resin having adhesive properties as the hydrophobic thermoplastic resin.

It goes without saying that the present invention is not limited to the embodiments described above.

Next, examples of the present invention will be described.

Example 1 Admer resin (C) (manufactured by Mitsui Petrochemical, modified polyolefin resin with adhesive properties), nylon 6-66 copolymer (B) (MP: 199 to 200°C), and ethylene content of 40 mol% The saponified ethylene-vinyl acetate copolymer (A) with a saponification degree of 95% or more was introduced into one die from three extruders so as to be stacked in that order, and heated at 240°C.
A three-layer film was obtained by coextrusion lamination.

After winding up this film, the volatile matter (water vapor) of the copolymer saponified film is removed by sealing it with a moisture-proof film made of polyethylene or the like.
The voltage was kept below 0.5%.

Then, just before performing metal vapor deposition, the moisture-proof packaging is opened and the above (
5) Aluminum was vapor-deposited (thickness: 0.03 μm) on the surface to obtain a metal-deposited film of the present invention.

Example 2 Low density polyethylene (D: 0.9].
8, M■: 7) was extruded at a T-die temperature of 320° C., and immediately extrusion laminated by pressing with a nip pressure of 10 kg/Cm to obtain a metal vapor-deposited laminated film with a protected vapor-deposited surface.

The peel strength between this metal vapor deposited surface and the polyethylene surface is 25
0g/15mm (tensile speed 200mm/min
, 20° C., 180° direction), which is a practically sufficient value.

Example 3 In the film of Example 2, on the admer resin surface,
Further, low-density polyethylene was melt-extruded and laminated to obtain a metal-deposited laminated film.

Comparative Example A film made of the saponified material and nylon 6-66 copolymer used in Example 1 was heated at 20°C without moisture-proof packaging.
The sample was stored at 80% RH for one week, and metal vapor deposition was performed on the saponified surface to obtain a metal vapor deposited film.

The above comparative data are shown in Table 1.

The method for measuring the physical property values listed in Table 1 is as follows.

Measuring method Curl degree: How many times is it curled from one measurement to the other? Measure whether Lum is involved.

Oxygen permeability: ASTM-DI434, 25°C-dryo
Moisture permeability: JIS-ZO208.

Impact resistance: Based on JIS-P8134 (23°C).

Rub and Friction Resistance Two cylinders are vacuum packed, the film that has entered the cylinder is pulled out of the cylinder and released, this is repeated and the corners of the cylinder are rubbed and the number of times until vacuum leakage is measured.

As mentioned above, the metal-deposited film of the present invention has gas barrier properties,
Since it has excellent moisture resistance, it is particularly suitable for use as a food packaging film.

Furthermore, since it has a light-shielding property, it not only prevents the contents from deteriorating due to light, but also prevents the curling phenomenon due to moisture absorption, making it convenient to handle, excellent in packaging suitability, and extremely beautiful packaging possible.

Furthermore, no pinholes, bubbles, etc. were generated.

The metallized film of the present invention is particularly suitable for use in vacuum packaging, gas exchange packaging, fragrance packaging, spoilage prevention packaging for oil-based foods, oil-resistant packaging, deep drawing packaging, etc., and as BIB films, etc. It can be used for various purposes.

Although a film has been described above, even if the thickness is sheet-like, it naturally falls within the technical scope of the present invention.

Claims (1)

[Claims] 1. Ethylene content 25-60 mol%, saponification degree 90%
A non-curling, gas-barrier, metal-deposited laminated film in which one of the inner layers consisting of the saponified ethylene-vinyl acetate copolymer layer and the polyamide resin layer is a metal-deposited layer, and the other outer layer is a hydrophobic thermoplastic resin layer. . 2 Ethylene content 25-60 mol%, saponification degree 90%
The above saponified ethylene-vinyl acetate copolymer (3), polyamide resin (B), and hydrophobic thermoplastic resin layer (
A/B/C or
A film is formed with the configuration B/A/C, and while maintaining the moisture-proof state after film formation, the above A
A method for producing a non-curling gas barrier metal-deposited laminated film, characterized in that metal vapor deposition is performed on the A side when the structure is /B/C, and on the B side when the structure is B/A/C. .