JPS602443A - Vessel made of synthetic resin having excellent gas barrier property - 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 improvements in containers made of synthetic resins such as polyethylene terephthalate (IT), polyethylene (pz), polypropylene (PP), and vinyl chloride (PVC).

After the war, research and development of synthetic resins was carried out rapidly, especially in Japan, and today it boasts the second largest production volume in the world after the United States, and its widespread use is expected to be applied not only to industrial products but also to household items. It is now possible to see them in every corner of the forest.

In recent years, there has been a remarkable rise in the rise of synthetic resin products in the field of various containers in daily social and domestic life, and in particular, with the spread of refrigerators, demand for airtight containers for food and beverages, etc. has increased. ing.

Conventional types of airtight containers were limited to metal cans and glass bottles, which did not satisfy the diversifying demand, but synthetic resins, especially those developed and put into practical use in the 1950s, With the advent of polyethylene, a wide range of applications is now possible. When synthetic resin containers first appeared, they were not very versatile, and t! : Because the production system was not established, the price was high, and the product did not become explosively popular.
However, compared to conventional materials such as metal and glass, it is lightweight, has high chemical resistance, is highly water resistant and does not corrode, has transparent materials such as acrylic resin and polycarbonate resin, and is shock and vibration resistant. It has been recognized for its longevity in terms of performance, such as being highly durable, highly abrasion resistant, good in moldability, and allows for free coloring, and has been widely used to this day.

On the other hand, as a result of the diversification of lifestyles, major changes have been made to dietary habits, including nine types of beer.
As the demand for so-called carbonated drinks such as ciders, colas, and carbonated fruit juices has increased, there has been a great deal of interest in their containers (airtight containers).

Conventionally, and currently, most of these containers have relied on glass bottles or metal cans, but the cost of materials, molding and processing, and transportation costs due to the weight of the materials are high. In addition to the direct problems faced by producers, such as problems in handling and damage, the collection of empty containers has become a major problem. In addition, accidental accidents caused by materials such as glass and metal are occurring one after another, and this is developing into a serious social problem.
The development of alternative container materials is desired.

For synthetic resins to replace current materials as container materials for food and beverages, the following conditions must be met.

(1) It is lighter than current materials, reducing transportation cost.

(2) Material cost is lower than current materials and easy to obtain.

(6) Molding cost is lower than current materials and moldability is good.

(4) Physical and mechanical properties such as impact resistance, vibration resistance, and abrasion resistance are superior to, or are close to, those of current materials.

(5) It is easy to add decorative elements such as coloring and designs.

(6) Chemically stable, with no material components mixed into or remaining in the contents.

(7) It has excellent gas-barrier properties, and must not allow oxygen, etc. from the outside air to get mixed in, or carbon dioxide gas, etc. from the contents to leak out.

As mentioned above, there are generally many synthetic resin materials that meet most of these conditions, and based on these conditions, various synthetic resins have been studied and researched as container materials. In addition, polyvinyl chloride resin (PVC) containers appeared on the market as containers for soy sauce, etc.

In particular, Japan is blessed with raw materials for vinyl chloride resin,
The price of resin has fallen below international prices, and it has developed as an industry suited to the country's circumstances. Since it has the characteristic of being able to be used as a material with a high hardness of 1, it can be said that it is one of the materials suitable as a material for containers.

However, it cannot be said that all the problems of residual materials and contaminants have been resolved, so there is room for consideration as to whether or not they are ideal containers for food and beverages. A vinyl chloride resin with extremely low carbon content has been developed, and some products have received government approval for use in food and beverage containers, so the results of research and development are eagerly awaited.

Furthermore, among the various conditions mentioned above for closed circulation containers used for food and beverages, the most stringent requirement is ``gas barrier properties.'' There is a major need to reduce the oxidation of the contents due to the contamination of oxygen in the outside air.

In particular, with regard to the containers used for carbonated beverages mentioned above, since the purpose is to mix carbon dioxide gas into the contents and close the containers, the internal pressure also increases, so there is a great need for barrier properties against carbon dioxide gas. Become.

Therefore, as a synthetic resin material with low gas permeability, especially carbon dioxide gas permeability, among saturated polyester polymers with ester bonds, it has no camphor properties and hardly decomposes under heat of about 100 degrees Celsius. Polyethylene terephthalate (
PET) has been attracting attention as a container material, and in addition to the above-mentioned features, this material is also being gradually put into practical use because it is lightweight and has excellent mechanical properties.

However, even PET does not have a complete barrier property against carbon dioxide gas, and in actual use, a metal foil such as aluminum is bonded to the outside of the PFiT container. In addition, attempts have been made to improve the gas barrier properties by applying a thin film of metal, etc. to the outer surface of the PBCT container by vacuum evaporation, spacing, etc. However, in either method, since the metal thin film is deposited on the PET substrate, the adhesion is extremely weak, and at the same time K does not change the physical properties of the PET substrate surface and is a definite gas. At present, no blocking effect has been achieved.

The present invention eliminates the drawbacks of the prior art as described above, and has a thin film of metal, its oxide, compound, or inorganic material, and its oxide, compound, etc. formed tightly on the surface, and has gas barrier properties. The purpose is to provide synthetic resin containers and their parts that are rich in

The purpose of the present invention is to coat the surfaces of synthetic resin containers and parts with thin films of metals, inorganic substances, etc. so that some of their molecules or atoms are
This is achieved by closely adhering the synthetic resin under the surface of the container as a base material in a bonded state with a part of the molecules or atoms of the synthetic resin, thereby imparting a high degree of gas barrier property to the surface of the container and parts.

The method is a special ion coating method in which a radio frequency electric field is applied to the substrate to form a film on the surface (for example, patent application No. 55-124409 filed by the same applicant). No.) etc. are used.

In the synthetic resin container according to the present invention, the barrier properties against gases, particularly carbon dioxide gas, and oxygen are significantly improved,
It can now be used in fields that were previously impossible, and it can also have effects such as greatly improving inventory life in currently used product fields.

Hereinafter, embodiments of the present invention will be disclosed in conjunction with the accompanying drawings,
At the same time, its features and effects will be explained in detail.

The attached figures are a comparison of the properties of a thin film formed by the prior art and a thin film according to the present invention, and a cross-sectional view of a container made of synthetic resin.

FIG. 1 shows a state in which a thin film 2 according to the prior art is laminated on the surface of a base material 1. As shown in FIG.

In this case, the bond between the base material 1 and the thin film 2 is not so strong, and they are easily separated due to mechanical or chemical causes. On the other hand, on the surface of the container according to the present invention, as shown in FIG. Alternatively, it is tightly attached to some atoms 5 while exhibiting a bonded state. According to Jugo/i4 Chu F Takashi, which shows a cross section of a container with such a structure, A7. Ni, Or,
A metal thin film 7 such as T1 is tightly formed. Moreover, on this thin film Z, as shown in FIG. 4, 810, Sio2.
AA! 20. , MflF2, and other inorganic substances, inorganic oxides, inorganic compounds, metal oxides, and metal compounds can be formed. Furthermore, as shown in FIG. 5, a thin film 8 of an inorganic substance is formed on the surface of the thin metal 11Q7 applied to the surface of the container B, and a thin film 9 of an inorganic substance or a compound of a metal and an inorganic substance is further formed thereon. , are formed densely using a special ionization coating method. By forming a multilayer thin film of various materials in this way, it is possible to improve not only gas barrier properties but also optional properties such as chemical resistance and alkali resistance.

The selection and combination of these materials can be freely implemented in a wide range of ways as long as they do not depart from the basic spirit of the present invention.

In the examples, polyethylene terephthalate) (P
ET) is used, and the surface is coated with s.
1o□8 was formed by a special ionization coating method, and an experiment was conducted to measure the permeability of each gas at room temperature of 26°C, and the following experimental results were obtained.

Based on the above experimental results, it is possible to apply a thin film of metal or a dense thin film of inorganic substances, inorganic oxides, inorganic compounds, metal oxides, metal compounds, etc. to the surface of containers made of synthetic resin using a special ionization coating method. As a result, its gas barrier properties and other properties have been significantly improved, making it suitable for practical use as containers for food and beverages, especially carbonated beverages such as beer, cider, cola, and carbonated fruit juice. .

Although the embodiments of the present invention have been shown, it is clear that the selection and combination of materials for thin films, the thickness of the thin film, etc. can be appropriately selected depending on the properties of the base material, the use and purpose of the product, etc. Dew.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional model diagram showing a state of a saw covered with a thin film according to the prior art. FIG. 2 is an enlarged cross-sectional model diagram showing the state of thin film formation in the container according to the present invention. FIG. 5 is a sectional view showing the +iii configuration of the container according to the present invention. Figures 4 and 5 show examples of container walls. The reference numerals in the figure correspond to the following. 1... Base material 2.3... Thin film 4... Molecules of thin film substance (Jfj, child) 5... Molecules (atoms) of base material substance 6... Container (plastic) 7... Metal thin film 8...Thin film such as metal compound 9...None (thin film such as a substitute) Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5

Claims (1)

[Claims] (1) A container made of a synthetic resin such as polyethylene terephthalate (PUT), polyethylene (PK), polypropylene (PP), or vinyl chloride (PVC), with AJ, Ni, Metal thin film such as Or, Ti, or 810.5in2. Thin films of inorganic substances such as Al2O, MgF2, metal oxides, or combinations thereof,
Alternatively, a synthetic resin container characterized in that a thin film made of a compound such as a metal, an inorganic substance, a metal oxide, a metal compound, an inorganic oxide, or an inorganic compound is tightly formed. (2. The synthetic resin container according to claim 1, wherein the thin film is a single layer. (6) The synthetic resin container according to claim 1, wherein the thin film is a multilayer. something that is.