JP4300977B2 - Barrier plastic container - Google Patents

Description

  The present invention is characterized in that a plastic container excellent in barrier properties and transparency, in particular, contents containing moisture and the moisture does not deteriorate even if the moisture contacts or adheres to the inner surface of the container. It relates to a barrier plastic container.

  Recently, plastic containers are widely used as packaging containers in various fields such as the food field and the pharmaceutical field because of their various characteristics such as easy molding, light weight, and low cost. However, plastic containers have properties such as the permeation of low molecular gases such as oxygen, carbon dioxide, and water vapor, the property that low molecular organic compounds adhere to the inside, and the property that there are elution components such as acetaldehyde. There were many points that had to be improved as a container.

  Various measures have been taken to solve these problems, but all have various problems, and the above problems cannot be solved completely. For example, as one of the methods for reducing the gas permeability of a plastic container, there are a method of forming a container having a laminated structure using a plurality of plastic materials, a method of manufacturing a container using a plastic material in which various plastic materials are blended, and the like. is there. However, when these methods are used, the gas permeability can be reduced to a certain extent, but the gas permeability cannot be reduced to a level that satisfies a container that requires a higher barrier property. In addition, the cost of the plastic material used in the above method is very high.

  On the other hand, in recent years, various techniques for coating a plastic thin film on a plastic container using a vacuum process such as a plasma CVD method have been developed, and plastic containers in which a ceramic thin film is formed by these techniques are widely available. Most of these are made by forming a ceramic thin film on the surface of a plastic molded article made of a single plastic material to improve the barrier property, and a container having an excellent barrier property can be obtained at low cost. (For example, refer to Patent Document 1). However, these plastic containers have a problem that when the surface on which the thin film is formed directly touches moisture or the contents containing moisture, the thin film deteriorates and the initial barrier property is lowered.

  The present invention has been made to solve the above-mentioned problems of the prior art, and the plastic container that constitutes the skeleton of the plastic container has the property that the plastic container is permeable to low molecular gases such as oxygen, carbon dioxide, and water vapor. Even if the content containing water or moisture stored inside is directly brought into contact with the inner surface of the container, the initial barrier property is not lowered, by forming a predetermined thin film on the surface of the substrate, and An object is to provide a barrier plastic container having high transparency.

In order to achieve such a problem, the invention according to claim 1 is characterized in that the layer thickness is 0.2 nm or more and 20 nm or less on the inner surface of a plastic container base made of a plastic material and molded into a container shape. In addition, an undercoat layer in which the composition of carbon and hydrogen is both 40% and 55% and a barrier layer made of silicon oxide having a layer thickness of 10 nm to 200 nm are laminated in this order. The barrier plastic container is characterized in that the total light transmittance of the laminated portion of the layers is 80% or more.
Japanese Utility Model Publication No. 5-35660

  The barrier plastic container of the present invention is excellent in barrier properties and transparency, and even if the content containing water or moisture is in direct contact with the inner surface of the container, the initial barrier property does not deteriorate.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a partial cross-sectional configuration explanatory view showing an embodiment of the barrier plastic container of the present invention. Under this barrier plastic container 1, which is the inner surface of the plastic container body 2 constituting the skeleton, 20 nm or less in thickness is 0.2nm or more, a 55% or less of the composition of carbon and hydrogen, both at 40% or more A coat layer 3 and a barrier layer 4 made of silicon oxide and having a layer thickness of 10 nm or more and 200 nm or less are laminated in this order. Moreover, the total light transmittance in the lamination | stacking part of each said layer is 80% or more.

  On the other hand, FIG. 2 shows an example of a conventional barrier plastic container 11. This barrier plastic container 11 is provided with a silicon oxide layer 14 laminated on the inner surface side of a plastic container base 12 constituting the skeleton, and is provided with an intended barrier property. However, in the case of the barrier plastic container 11 in which only the silicon oxide layer 14 is laminated on the inner surface of the plastic container base 12 as described above, for example, contents containing moisture directly touch the silicon oxide layer 14. As a result, there is a problem in that moisture migrates and permeates into the silicon oxide layer, the interface between the plastic container base 12 and the silicon oxide layer 15 is deteriorated, and the initial barrier property is lowered.

However, as in the barrier plastic container of the present invention, an undercoat layer in which the composition of carbon and hydrogen is both 40% and 55% is interposed between the barrier layer and the plastic container substrate, and the layers of each layer When the thickness is set within the above range, the adhesion between the barrier layer and the plastic container substrate is improved and the interface can be prevented from being deteriorated. For example, the content containing moisture is contained in the inner layer. Even if touched directly, the initial barrier property can be maintained.

  The plastic container base 2 is made of a plastic material such as polyethylene, polypropylene, polyethylene terephthalate, and polyimide, and is obtained by molding these plastic materials into a container shape by a molding method such as blow molding, injection molding, or extrusion molding. It is.

Further, in order to form a higher undercoat layer 3 of the flexible, constituted by the material mainly composed of carbon and hydrogen, the composition of the carbon and hydrogen together with 40% to 55% or less .

As a method of forming the undercoat layer 3 in which both the carbon and hydrogen compositions are 40% or more and 55% or less, the inner surface of the plastic container base 2 molded in a three-dimensional form is uniform and low in thickness. Since a thin layer can be formed at low cost, it is desirable to use a plasma assisted CVD method using a hydrocarbon gas such as acetylene, methane, ethane, or propane.

  Also, as a method for forming the barrier layer 4 made of silicon oxide, for the same reason, a plasma-assisted CVD method using an organosilicon compound monomer gas such as hexamethyldisiloxane, tetramethyldisiloxane, tetraethoxysilane or the like is used. It is desirable to use it.

  In order to sequentially deposit the undercoat layer 3 mainly composed of carbon and the barrier layer 4 composed of silicon oxide on the inner surface of the plastic container base 2 using the plasma-assisted CVD method, for example, as shown in FIG. A film forming apparatus is used to form a film as follows.

In film formation, first, the inside of the chamber of the apparatus is evacuated and then a hydrocarbon gas is introduced therein. Next, high frequency power is applied from the high frequency power source 24 to the external electrode 25 to generate plasma between the external electrode 25 and the internal electrode 27, and this time, the organosilicon compound monomer gas is supplied while continuing to apply the high frequency power. Introduced plasma to generate an undercoat layer 3 and silicon oxide on the inner surface of the plastic container substrate with a layer thickness of 0.2 nm to 20 nm and a composition of both carbon and hydrogen of 40% to 55%. A barrier layer 4 made of a material is sequentially laminated.

The undercoat layer 3 in which the composition of carbon and hydrogen is both 40% or more and 55% or less is often colored, and it is necessary to reduce the layer thickness in consideration of the expression of high light transmittance. Although this layer thickness depends on the purpose of use of the container and the like , as described above, it is in the range of 0.2 nm or more and 20 nm or more. Further, the thickness of the barrier layer 4 made of silicon oxide is set in a range of 10 nm or more and 200 nm or less because a barrier property such as oxygen or water vapor decreases when the thickness is 10 nm or less and a crack is formed when the thickness is 200 nm or more. And the total light transmittance of the laminated part of the undercoat layer 3 and the barrier layer 4 shall be 80% or more.

  Hereinafter, the barrier plastic container of the present invention will be further described with specific examples.

  Using a film forming apparatus whose main part configuration is shown in FIG. 3, an undercoat layer mainly composed of carbon and silicon oxide on the inner surface of a polyethylene terephthalate (PET) container base having a capacity of 500 ml as follows: A barrier layer made of a material was sequentially formed.

First, after introducing acetylene into a PET container substrate set in the chamber of the film forming apparatus through a gas introduction pipe with a gas flow rate of 10 cc / min, the pressure during film formation is 0.5 torr, and the high frequency power to be applied. Was deposited at 250 watts. Further, following the above process while applying 250 watts of high-frequency power, this time, a mixed gas of hexamethyldisiloxane and oxygen was introduced into the PET container substrate through the gas introduction pipe at a gas flow rate of 500 cc / min. A film was formed on the inner surface of the container, and the barrier plastic container of the present invention according to Example 1 was obtained. At this time, the layer thickness of the undercoat layer that consists in construction material composed mainly of carbon and hydrogen of the first layer is 2 nm, the layer thickness of the barrier layer of a second layer of silicon oxide It was 50 nm.

  Table 1 shows the oxygen barrier property data measured by OXTRAN manufactured by MOCON, and the total light transmittance data measured by Haze Meter NDH2000 manufactured by Nippon Denka Kogyo Co., Ltd. for the obtained barrier plastic container. Table 1 also shows oxygen barrier property data measured by OXTRAN manufactured by MOCON of the barrier plastic container after the obtained barrier plastic container was filled with water and stored at 40 ° C. for 30 days.

Constituting a part of a barrier plastic container, formed under the same conditions as in Example 1 except that the layer thickness of the undercoat layer that consists in construction material composed mainly of carbon and hydrogen content of 10nm The barrier plastic container of the present invention according to Example 2 was obtained.

  Table 1 shows the oxygen barrier property data measured by OXTRAN manufactured by MOCON, and the total light transmittance data measured by Haze Meter NDH2000 manufactured by Nippon Denka Kogyo Co., Ltd. for the obtained barrier plastic container. Table 1 also shows oxygen barrier property data measured by OXTRAN manufactured by MOCON of the barrier plastic container after the obtained barrier plastic container was filled with water and stored at 40 ° C. for 30 days.

Perform film formation under the same conditions as in Example 1 except that the layer thickness of the undercoat layer that consists in construction material composed mainly of carbon and hydrogen content of 40 nm, for comparison according to Example 3 A plastic container was obtained.

  Table 1 shows the oxygen barrier property data measured by OXTRAN manufactured by MOCON and the total light transmittance data measured by Haze Meter NDH2000 manufactured by Nippon Denshoku Kogyo Co., Ltd. Table 1 also shows the oxygen barrier property data measured by OXTRAN manufactured by MOCON of the plastic container after the obtained plastic container was filled with water and stored at 40 ° C. for 30 days.

  A film was formed under the same conditions as in Example 1 except that only hexylenedisiloxane and oxygen mixed gas was used instead of acetylene as a source gas, and a plastic container for comparison according to Example 4 was prepared. Obtained. At this time, the thickness of the barrier layer made of silicon oxide was 50 nm.

  Table 1 shows the oxygen barrier property data measured by OXTRAN manufactured by MOCON and the total light transmittance data measured by Haze Meter NDH2000 manufactured by Nippon Denshoku Kogyo Co., Ltd. Table 1 also shows the oxygen barrier property data measured by OXTRAN manufactured by MOCON of the plastic container after the obtained plastic container was filled with water and stored at 40 ° C. for 30 days.

  Film formation was performed under the same conditions as in Example 1 except that the thickness of the silicon oxide layer was 10 nm, and a plastic container for comparison according to Example 5 was obtained.

  Table 1 shows the oxygen barrier property data measured by OXTRAN manufactured by MOCON and the total light transmittance data measured by Haze Meter NDH2000 manufactured by Nippon Denshoku Kogyo Co., Ltd. Table 1 also shows the oxygen barrier property data measured by OXTRAN manufactured by MOCON of the plastic container after the obtained plastic container was filled with water and stored at 40 ° C. for 30 days.

It is a partial cross-section block explanatory drawing which shows the barrier plastic container of this invention. It is a partial cross-section block explanatory drawing which shows an example of the conventional barrier plastic container. It is explanatory drawing which shows an example of a structure of the film-forming apparatus used when producing the barrier plastic container of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 11 ... Barrier plastic container 2, 12 ... Plastic container base | substrate 3 ... Undercoat layer 4 ... Barrier layer 14 ... Silicon oxide layer 24 ... High frequency power supply 25 ... External electrode 26 ... external electrode canopy 27 ... internal electrode 28 ... insulating plate 29 ... gas supply hole

Claims (1)

An undercoat made of a plastic material and having a layer thickness of 0.2 nm to 20 nm and a composition of carbon and hydrogen of both 40% and 55% on the inner surface of a plastic container base formed into a container shape And a barrier layer made of silicon oxide having a layer thickness of 10 nm or more and 200 nm or less, and a total light transmittance of a stacked portion of the two layers is 80% or more. Barrier plastic container.

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