JPS5898251A - High barrier composite film and package - 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 The present invention relates to a packaging composite film having high oxygen gas barrier properties and water vapor barrier properties, and a package using the film.

In food and drug packaging, good oxygen and water vapor barrier properties are a key factor in extending the shelf life of the product, and various improvements have been made to improve these barrier properties.

In terms of oxygen barrier properties, saponified ethylene-vinyl acetate copolymer (EV musaponized product) is one of the most excellent resins in terms of ``fAIR'' and is therefore widely used in food packaging and the like. However, this resin has a serious drawback in that it has a high water absorption rate and its P4 properties are significantly reduced when it absorbs water, so in order to compensate for this drawback, nine different composite films are being considered by combining it with other resins. For example, P4'
Adhesive layer (A(1)/11iVA saponified material/A(1)
/ Pf! (Like D, a composite film with a layered structure in which both sides are sandwiched with resins such as PI and PP with good moisture resistance has been put into practical use, but even this structure is insufficient if further barrier properties are required. Therefore, further improvements were required.

iv Mu saponified resin is the best oxygen barrier resin under dry conditions, but some foods are exposed to considerable moisture, and in this case, when MV Mu saponified material absorbs water, its barrier properties decrease significantly. Even in the construction of a composite film, the scope of use of the resin had to be restricted.

Furthermore, since the conditions under which the packaging body is placed vary widely, harsh conditions must be set, and the composition of the composite film used as the packaging material also needs to have a sufficient composition in terms of barrier properties. Ta.

For this reason, various studies have been conducted to see if it is possible to create a layer structure for a composite film using saponified EVA that can be used even under humid conditions, that is, whether it is possible to create a layer structure that does not reduce its oxygen barrier properties even under high humidity conditions [7. We completed a film and a package using the film.

The composite film and package of the present invention generally include a package VC
In this case, moisture permeates into the packaging material from the outside or inside depending on the humidity conditions inside and outside the package.
By providing a hydrophilic resin f- before reaching the kVA saponified layer of -, water intrusion into the EvA saponified layer is prevented by 1 liter.
7 to keep the EVA saponified layer dry by
In this way, the EvA saponified product exhibits the most effective oxygen barrier property.

Taking into account the moisture content of the package, the environmental atmosphere in which the package is placed, etc., the water-resistance resin layer can be provided at an appropriate thickness on both sides or on either side of the 1CvA saponified product. The water-absorbing resin layer 2 may be a composition obtained by blending a so-called drying substance such as calcium chloride or silica gel with a thermoplastic resin, a starch-based water-absorbing polymer such as a combination of denguin-acrylonitrile graft 1, or a cellulose-based water-absorbing polymer. Any resin having a high water-absorbing performance may be used, such as a composition obtained by blending a thermoplastic resin with a synthetic resin-based water-absorbing polymer such as molecule, polyacrylate-based, polyvinyl alcohol-based, or polyethylene oxide-based polymer. The mixing ratio of the drying substance to the thermoplastic resin is desirably higher in terms of water absorption performance, but it varies depending on film forming suitability, strength, etc., and compatibility with the resin, but is usually 30 to 150 parts. In the case of synthetic resin polymers, 10 to 100 sites are desirable.

In addition to the KVA saponified layer and the water-absorbing resin layer, the composite film of the present invention is provided with other thermoplastic resin layers depending on the application and required performance, and is produced by dry lamination, extrusion lamination, or coextrusion lamination.

This will be explained below using examples.

Examples 1 to 3 As a water-absorbing resin layer, the following water-absorbing substance was added to LDPR by cooling and using a resin composition, the following one-layer structure 12 was prepared by coextrusion method.
A 0μ film was made.

Pi; /Water-absorbing resin layer Act /EV Aket/v
Transformation? ! I/A(1/PK(I11μ) (additional μ)
(5μ) (1 (1μ) (5μ) (30μ) 1 time
Mouth 1 External Example 1
Addition of 30% by weight of acrylic super absorbent polymer 2
Calcium chloride 〃〃 3 Silica gel 〃Comparative example 1 A molded container with a diameter of 100wn and depth of 20cm was made from these additive-free films, and PFiT (12μ) / Az (1
The oxygen permeability of the heat-sealed container was measured using a film of 5μ)/Pffl (40μ) and the results are shown in Table 1.
Shown below.

0 goose transmission it (Co/24hr) *Humidity inside the container

Claims (2)

[Claims] (1) The film is characterized by containing a water-absorbing resin layer in which one or more of a water-absorbing polymer, calcium chloride, and silica gel is dissolved in a thermoplastic resin, and a saponified ethylene-vinyl acetate copolymer layer in the 11-layer film. High barrier composite film. (2) Packaging body 1° made of the composite film described in 411 claim (1)