JPH04115940A - Packing film - Google Patents

Abstract

PURPOSE:To obtain a colorless transparent packing film excellent in gas barrier properties and enhanced in heat resistance, strength and flexibility by successively laminating an SiOx layer in the state mutually mixed with the structure of a base material composed of a flexible plastic film and an SiO2 film to at leas the single surface of the base material. CONSTITUTION:A flexible plastic film becoming a base material 3 is composed of polyethylene, polypropylene, a copolymer containing ethylene as a main component or a copolymer containing propylene as a main component and, as a material for forming a membrane layer, one having high vapor pressure is pref. and SiO is suitable. Next, in order to form the SiOx layer 2 mixed with the structure of the base material, energy of several ten-several hundred eV is applied to film forming particles in an oxygen free atmosphere. Further, when the SiO2 film 1 is formed on the SiOx layer 2 by vacuum vapor deposition using SiO as a raw material, O2 gas is usually introduced into the atmosphere in order to enhance the degree of oxidation. By this method, since an Si-Si bond is formed at the interface between the base material 3 and the SiOx layer, high density and strength are developed without losing excellent barrier properties and the flexibility of the base material.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a packaging film, and more specifically, it has excellent gas barrier properties such as moisture resistance, fragrance retention, and antioxidant properties, as well as heat resistance, strength, and flexibility. The present invention relates to a highly durable, colorless and transparent packaging film.

(Prior art) In recent years, with the spread of microwave ovens in households, the market for food packaging materials using packaging films made from flexible plastic films that can be distributed at room temperature and can be used in microwave ovens along with the packaging material has expanded. There is.

Characteristics required for food packaging films include: ■ Excellent gas barrier properties such as moisture resistance, aroma retention, and antioxidant properties; ■ Sufficient strength and flexibility; ■ Applicability to heat and pressure sterilization. ,and so on.

Conventionally, packaging materials that meet the above characteristics are made using a flexible plastic film as a base material, on the surface of which metal oxides such as aluminum oxide, magnesium oxide, and silicon oxide are vapor-deposited, and with other films laminated on the vapor-deposited surface. Films have been proposed (JP-A-58-148759, JP-A-1-206036, JP-A-1-267036).
No., JP-A-2-34330).

In particular, packaging films made by vacuum-depositing silicon oxide have excellent water resistance, so their gas barrier properties are less likely to deteriorate before and after retort sterilization, or due to changes in the environment in which packaging materials and foods are placed, making them suitable as packaging materials that meet the above characteristics. It is being used.

[Problem to be solved by the invention]

However, when a silicon oxide thin film layer is used, (1) If a silicon oxide thin film is to have gas barrier properties that can be stored at room temperature for a long period of time, 1,500 to 2,000 people are required to form the film, resulting in high costs.

■ The film tends to crack when bent, causing problems in gas barrier properties and adhesion. Therefore, its use is limited to packaging forms that can avoid folding, such as standing pouches.

■ Although the SiOx layer created by vapor deposition using SiO as a raw material is transparent, it has a pale yellow color that makes it look bad and is not suitable for food packaging.
When t is used as a raw material, colorless and transparent 5 is obtained by vacuum evaporation method.
Although it is possible to form an IFT film, the evaporation rate is slow due to the low vapor pressure, making it unsuitable for large-area, mass-production applications such as packaging films.

The following shortcomings remained unresolved.

The present invention provides a colorless and transparent packaging film that has excellent gas barrier properties such as moisture proofing, fragrance retention, and antioxidant properties, and has high heat resistance, strength, and flexibility.

[Means to solve the problem]

That is, the present invention has been made in order to solve the problems that existed in the past, and includes S i Ox mixed with the structure of the base material on at least one side of a base material made of a flexible plastic film. Jii (
0≦χ<2), the above-mentioned problem was solved by a packaging film formed by sequentially laminating SiO and films.

[Effect]

In the packaging film according to the present invention, a SiOx layer (0≦X×2) and a SiO□ film are laminated in order from the base material side on at least one side of a flexible plastic film as a base material, and the above-mentioned Sin.

The layer is in a state in which the base material structure and the Sin structure are mutually mixed.

As a result, a 5i-3i bond is formed at the interface between the base material and the SiOx layer, thereby achieving excellent gas barrier properties and high adhesion strength without losing the flexibility of the base material.

[The flexible plastic film that serves as the base material used in the detailed description of the invention refers to olefin resins such as polyethylene polypropylene, copolymers containing ethylene as a main component, copolymers containing propylene as a main component, polyethylene terephthalate, and Polyesters such as petite lenticorephthalate, nylon, polyvinyl chloride, polyvinylidene chloride.

Examples include films such as polyvinyl alcohol. These films may be produced by any method, and may be either unstretched or stretched.

The thickness of the base material is preferably selected in the range of 5 to 1000 μm, particularly preferably in the range of 10 to 100 μm.

Note that, in order to improve the adhesion between the base material and the thin film layer, it is preferable that the surface of the base material on which the thin film layer is to be formed is pretreated in advance. Pretreatment includes electric discharge treatment, flame treatment,
Examples include chemical treatment and application of an anchor coating agent.

As a method for forming a thin film layer on a base material, a normal vacuum evaporation method is preferable from the viewpoints of reducing costs and increasing productivity due to its use as a packaging material.

The raw material for forming the thin film layer should preferably have a high vapor pressure, and SiO is suitable.

Next, in order to create a SiOx layer mixed with the base material structure, it is necessary to apply energy of several tens to several hundreds of eV to the film-forming particles in an oxygen-free atmosphere.

For this purpose, there are methods such as generating Ar plasma between the explosive source and the substrate to ionize the film-forming particles, or ionizing the film-forming particles by irradiating them with thermoelectrons, but these methods do not penetrate into the base material structure. This is not the case if energy can be applied to the film-forming particles to form a mixed layer of the 5iC1+ layer and the base material.

Note that the thickness of the SiOx layer requires at least about 10 people in order to achieve the desired gas barrier properties. Also, Si
n, if the layer thickness is too thick, colorless transparency will be lost, so 50~
It is preferable to set the number within 100 people.

Furthermore, when the SiO film formed on the SiOx layer is formed by vacuum evaporation using SiO as a raw material, 0° gas is usually introduced into the atmosphere to increase the degree of oxidation. Further, in order to improve film quality, film formation can be performed by generating plasma in a zero gas atmosphere. ○／Si
If the ratio is 2, the film will be colorless and transparent, so any method is not particularly limited as long as it can produce a film with such a composition.

Regarding the thickness of the Si0g film, the thinner it is, the more it will lead to a reduction in manufacturing costs, but the more it will lead to deterioration of the gas barrier properties. Conventional packaging films do not have sufficient gas barrier properties even when deposited with a film thickness of about 1,500 people, but the packaging film of the present invention does not have sufficient gas barrier properties.
Although it has good gas barrier properties even when the thickness of the film is 1500 Å or less, the preferred thickness of the film is 500 to 12
The range is 00 people.

In addition, the packaging film of the present invention has a colorless and transparent 34 ml film on the surface of the base material made of flexible plastic.
It is also possible to create this by first forming a 0g thin film and then implanting Si ions from the surface of the thin film to the interface between the film and the base material. In this case as well, the thin film production method is CV
Any method such as the D method, sputtering method, or vacuum evaporation method may be used.

Furthermore, for the purpose of improving heat sealability, the packaging film of the present invention may be laminated with other flexible plastic films via an adhesive or the like.

[Example 1] An example of the packaging film according to the present invention will be described in detail using FIG. 1.

In the figure, 1, 2, and 3 are SiO□ films, respectively.

S i Ox layer represents the substrate. It is thought that the interface between the base material 3, the Sin layer, and the layer 2 has a coexistence of mutual structures, as will be described later.

As a base material, 100 people formed a Niyori SiOx (X = 1.7) layer using the Ar ion blating method on the surface of a 12 μm thick PET film (manufactured by Tijin Co., Ltd.), and 02 gas reaction was performed on it. A 5iOz film was deposited by 1,100 people using a vapor deposition method to produce a packaging film. Note that 5iO (5 to 10 mesh manufactured by Osaka Titanium Co., Ltd.) was used as the evaporation material.

In addition, the structure of the packaging film in the film thickness direction was determined by photoelectron spectroscopy using ESCA spectra (S izp, Cp
s, 0Ss), a spectrum indicating the presence of 5t-3i bonds appeared at the interface between the base material and the SiOx layer. Further, in a similar measurement when PET as a base material was exposed by performing Ar ion beam etching in the film thickness direction, a spectrum indicating the presence of Cps and Si appeared.

As a result, the structures of both the base material and the 5inX layer are mixed at the interface, and the 5inX layer is further
It was found that a 5i bond exists.

The oxygen permeability of the packaging film produced in the above steps was measured in an oxygen atmosphere at 25°C and 100% RH. In addition, the transmittance of light was measured using a spectrometer. The measurement wavelength range is 190 μm to 700 μm. The measurement results are shown in Table 1.

[Example 2] Using the same base material as in Example 1, a SiO layer (X = 1°7) was formed on it by Ar ion blating method by 50 people, and an SiO layer was formed by 0□ gas reaction vapor deposition method. Rem made by 1150 people.

The oxygen transmittance and light transmittance of the above packaging film were measured in the same manner as in the examples. The measurement results are shown in Table 1.

(Comparative Example 1) Using the same base material as in Example 1 and using the same method as in Example 1, 1200 people produced SiO films.

The oxygen transmittance and light transmittance of the above packaging film were measured in the same manner as in the examples. The measurement results are shown in Table 1.

[Comparative Example 2] Using the same base material as in Example 1 and using the same method as in Example 1, 1200 people produced a SiOx layer.

The oxygen permeability and light transmittance of the above packaging film were determined in the same manner as in the Examples. The measurement results are shown in Table 1.

Table 1 Therefore, the food packaging material using the packaging film according to the present invention can be stored for a long time, can be packaged in a folded state, and has a good appearance because it is colorless and transparent.
It is particularly suitable as a food packaging material for microwave ovens.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the packaging film according to the present invention. 1...Sin, membrane 2...SiOx layer 3...base material [Effects of the invention] The packaging film according to the present invention is moisture-proof and fragrance-retentive. It has excellent gas barrier properties such as antioxidant properties, high heat resistance, strength, and flexibility, and is colorless and transparent. In addition, large-area, mass-production is possible using ordinary film-forming equipment. Patent application: Kazuo Suzuki, Representative of Toppan Printing Co., Ltd.

Claims (2)

[Claims] (1) On at least one side of the base material made of a flexible plastic film, a SiOx layer (0≦X<2), a Si
A packaging film made by sequentially laminating O_2 films. (2) The packaging film according to claim (1), wherein the SiOx layer is mixed with a base material structure.