JP4333382B2 - Gas barrier plastic container - Google Patents

Description

  The present invention relates to a gas barrier container, and more particularly to a plastic container having an improved gas barrier property by forming a plurality of deposited thin film layers on the inner surface of the container.

Conventionally, plastic containers have been widely used as packaging containers in various fields such as the food field and the pharmaceutical field due to various characteristics such as easy molding, light weight, and low cost. However, plastic containers are improved as containers, such as the ability to permeate low molecular gases such as oxygen, carbon dioxide, and water vapor, the property that low molecular organic compounds are adsorbed on the inner wall, and various elution components. There were many aspects that had to be added. Various measures have been taken to solve these problems. For example, as a method for reducing the gas permeability of a plastic container, a method of laminating a vinylidene chloride resin or ethylene / vinyl alcohol copolymer resin having a gas barrier property or using a blend resin is used. ing. However, laminating vinylidene chloride-based resins is not preferable because it causes generation of dioxins, such as generation of chlorine gas in incineration after use. In addition, when an ethylene / vinyl alcohol copolymer resin is laminated, it has a relatively excellent oxygen gas barrier property in a dry state, but has a humidity dependency and has a drawback that the gas barrier property is remarkably lowered when the humidity is high. Have. Furthermore, when these resins are used, the gas permeability can be reduced to some extent, but it is insufficient when a higher gas barrier property is required. Further, the cost of the gas barrier resin to be used is very high. In recent years, a technique for depositing an inorganic compound as a gas barrier layer on a thermoplastic resin has been known, and a gas barrier plastic container having an inorganic compound deposited thin film layer laminated on the inner surface of a molded container has been put on the market. Usually, a plastic container expands and contracts due to temperature change or moisture absorption during use, or deforms during transportation or storage. The gas barrier plastic container is subjected to great stress on the vapor deposition thin film layer on the inner surface of the container during expansion / contraction / deformation, and the thin film is cracked or peeled off, resulting in deterioration of gas barrier properties. It was. In order to improve the problem, a gas barrier plastic material in which a multilayer silicon compound thin film layer is laminated on a base material layer has been proposed (see, for example, Patent Document 1).
JP 7-32531 A

  However, in the proposed gas barrier plastic material, the silicon compound thin film layers are laminated in multiple layers, and the adhesion strength at the interface between the silicon compound thin film layers or at the interface between the silicon compound thin film layer and the innermost layer of the container. Has been disadvantageous, such as a decrease in color and the silicon compound thin film layer being colored.

  The problem of the present invention is that the multilayer deposited thin film layer laminated on the innermost layer surface of the plastic container is transparent and is excellent in that the deposited thin film layer is cracked or not peeled off during transportation and storage. An object of the present invention is to provide a plastic container capable of maintaining gas barrier properties.

The invention according to claim 1 of the present invention is the first vapor-deposited thin film layer made of an organosilicon compound having a carbon atom ratio of 10 to 20% on the innermost layer surface of the plastic container, wherein the carbon atom ratio is less than 5%. A second vapor-deposited thin film layer composed of an organosilicon compound and SiOx (x = 2 to 2.5) and a third vapor-deposited thin film layer composed of an organosilicon compound having a carbon atom ratio of 10 to 20% are sequentially laminated. It is a gas barrier plastic container characterized by the above.

  The invention according to claim 2 of the present invention is the invention according to claim 1, wherein the film thickness of the first vapor deposition thin film layer and the third vapor deposition thin film layer is 10 to 100 nm, and the film thickness of the second vapor deposition thin film layer is A gas barrier plastic container having a thickness of 5 to 50 nm.

  The gas barrier plastic container of the present invention is a first vapor-deposited thin film layer made of an organic silicon compound having a carbon atom ratio of 10 to 20% on the innermost layer surface of the plastic container, and an organic silicon having a carbon atom ratio of less than 5%. A second vapor-deposited thin film layer composed of a compound and SiOx (x = 2 to 2.5), and a third vapor-deposited thin film layer composed of an organosilicon compound having a carbon atom ratio of 10 to 20%. Since the film thickness of 1 vapor deposition thin film layer and the 3rd vapor deposition thin film layer is 10-100 nm and the film thickness of 2nd vapor deposition thin film layer is 5-50 nm, transparency is good and each vapor deposition thin film layer is carried during transportation and storage. The thin film is not cracked or peeled off, and excellent gas barrier properties can be maintained.

  The gas barrier plastic container of the present invention will be described in detail below along the embodiments. FIG. 1 is a cross-sectional view showing an embodiment of a gas barrier plastic container according to the present invention. Two vapor-deposited thin film layers (13) and a third vapor-deposited thin film layer (14) are sequentially laminated, and have an opening (15) at the upper end. The plastic container may be either a single layer or a multilayer.

  As the resin of the innermost layer (11) of the plastic container, polyolefin resin such as polyethylene resin and polypropylene resin, polyester resin, polyamide resin and the like are mainly used.

  The first vapor-deposited thin film layer (12) is provided for improving the adhesion to the innermost layer (11) of the container in addition to providing gas barrier properties, and an organic silicon compound having a carbon atom ratio of 10 to 20%. It is made up of. When the ratio of the number of carbon atoms is less than 10%, the adhesion is deteriorated, and when the ratio of the number of carbon atoms exceeds 20%, the thin film is colored and the transparency is impaired. Since the composition of the organosilicon compound is in the range described above, the adhesiveness with the innermost layer (11) is high, and the thin film is not cracked or peeled off when the plastic container is expanded or contracted or deformed.

  The second vapor-deposited thin film layer (13) is provided to give better gas barrier properties, and is composed of an organosilicon compound having a carbon atom ratio of less than 5% and SiOx (x = 2 to 2.5). It has become. In this case, SiOx (x = 2 to 2.5) is the main component. When the ratio of the number of carbon atoms is 5% or more and the value of x in SiOx is x <2 or x> 2.5, the gas barrier property is drastically lowered.

  The third vapor-deposited thin film layer (14) is provided to protect the second vapor-deposited thin film layer (13) in addition to providing gas barrier properties, and is made of an organic silicon compound having a carbon atom ratio of 10 to 20%. ing. When the ratio of the number of carbon atoms is less than 10%, the adhesion is deteriorated, and when the ratio of the number of carbon atoms exceeds 20%, the thin film is colored and the transparency is impaired.

  As described above, the second vapor-deposited thin film layer (13) is provided between the first vapor-deposited thin film layer (12) and the third vapor-deposited thin film layer (14), thereby cracking the thin film when the plastic container expands and contracts or deforms. No thin film is peeled off and excellent gas barrier properties can be maintained, and performance deterioration during use of a plastic container can be suppressed.

  A method for forming the first vapor-deposited thin film layer (12), the second vapor-deposited thin film layer (13), and the third vapor-deposited thin film layer (14) will be described below. In a vacuum film forming apparatus, a cylindrical chamber made of SUS304 is used. A plastic container is installed upside down, and a raw material gas nozzle that also serves as an earth electrode is inserted into the plastic container to introduce a raw material gas and a reactive gas, and each gas flow rate is sequentially changed to introduce high frequency power. Alternatively, it is formed by a chemical vapor deposition method in which a microwave power is applied to form a thin film. By successively changing each gas flow rate, it is possible to form a film continuously. In this case, the first vapor-deposited thin film layer (12), the second vapor-deposited thin film layer (13), and the third vapor-deposited thin film layer (14 ), The thin film composition continuously changes at each boundary surface, so that the adhesion between the thin films is greatly improved.

  Further, the film thickness of the first vapor-deposited thin film layer (12) and the third vapor-deposited thin film layer (14) is preferably 10 to 100 nm, and if it is less than 10 nm, the effect of protecting from various stresses cannot be expected and exceeds 100 nm. The thin film is colored, and the distortion increases, which is not good. Furthermore, the film thickness of the second deposited thin film layer (13) is preferably 5 to 50 nm. If it is less than 5 nm, the gas barrier property is inferior, and if it exceeds 50 nm, cracks tend to occur.

  As the source gas, hexamethyldisiloxane (hereinafter referred to as HMDSO) or trimethylsiloxane can be used as a main gas, and as a reactive gas, in addition to oxygen, ozone, Carbon dioxide or the like can be used.

  The gas barrier plastic container of the present invention will be described below with reference to specific examples, but the present invention is not limited to these examples.

  Using a polyethylene terephthalate resin, a cylindrical container with a 500 ml stretch-molded volume, an inner diameter of 25 mm, an average wall thickness of 0.5 mm and a narrowed neck is placed in a cylindrical chamber made of SUS304 in a vacuum film forming apparatus. The opening was turned upside down, and a raw material gas nozzle also serving as a ground electrode was inserted into the cylindrical container. HMDSO was flowed as a source gas at a rate of 10 ml / min in terms of gas standard state, oxygen was flowed at 50 ml / min as a reaction gas, and a high frequency power of 13.56 MHz was applied at 200 W for 2 seconds to form a film. A thin film layer (12) was formed. Next, the flow rate was continuously changed, HMDSO was flowed at 2 ml / min, oxygen was flowed at 100 ml / min, and high-frequency power was applied at 200 W for 8 seconds to form a second evaporated thin film layer (13). And laminated. Further, HMDSO was flowed as a raw material gas at a rate of 10 ml / min in terms of gas standard state, oxygen was flowed as a reaction gas at 50 ml / min, and a high frequency power of 13.56 MHz was applied at 200 W for 2 seconds to form a film. A vapor-deposited thin film layer (14) was formed and laminated to obtain a gas barrier plastic container of the present invention.

  In Example 1, the gas barrier plastic container of the present invention was obtained in the same manner except that HMDSO was flowed at 5 ml / min as the source gas of the first vapor-deposited thin film layer (12) and oxygen was flowed at 100 ml / min as the reaction gas. It was.

  In Example 1, HMDSO was flowed at 15 ml / min as a source gas for the first vapor-deposited thin film layer (12) and the third vapor-deposited thin film layer (14), and high-frequency power of 13.56 MHz was 5 at 200 W during the film formation of each layer. A gas barrier plastic container of the present invention was obtained in the same manner except that the film was formed by applying for 2 seconds.

  In the following, comparative examples of the present invention will be described.

  As a source gas for the first vapor-deposited thin film layer and the third vapor-deposited thin film layer, HMDSO was flowed at a rate of 5 ml / min in terms of gas standard state, and oxygen was flowed as a reactive gas at a rate of 100 ml / min. A comparative gas barrier plastic container was obtained in the same manner as in Example 1 except that power was applied at 200 W for 1 second to form a film.

  As source gas, HMDSO was flowed at 2 ml / min in terms of gas standard state, oxygen was flowed as reaction gas at 100 ml / min, and high frequency power of 13.56 MHz was applied at 200 W for 12 seconds, and only the first deposited thin film layer was supplied. A comparative gas barrier plastic container was obtained in the same manner as in Example 1 except that was formed.

<Evaluation>
Using the gas barrier plastic container according to the present invention of Examples 1 to 3 and the gas barrier plastic container for comparison of Examples 4 to 5, each deposited thin film layer in which the plastic container was laminated with an X-ray photoelectron spectrometer In addition to performing the elemental analysis, each plastic container was filled with distilled water and the oxygen permeability of the container after being dropped 10 times from a height of 1 m onto the concrete floor was measured and evaluated. The results are shown in Table 1.

表１に示すように、実施例１〜３の本発明のガスバリア性プラスチック容器は、落下試験後も酸素透過度が小さく、各蒸着薄膜層の薄膜が損傷していないことを示しており、実施例４〜５の比較用のガスバリア性プラスチック容器は、落下試験後の酸素透過度が大きく、各蒸着薄膜層が損傷していることが判明した。

As shown in Table 1, the gas barrier plastic containers of Examples 1 to 3 of the present invention have low oxygen permeability even after the drop test, indicating that the thin film of each deposited thin film layer is not damaged. It was found that the gas barrier plastic containers for comparison in Examples 4 to 5 had large oxygen permeability after the drop test, and the respective deposited thin film layers were damaged.

It is a sectional side view which shows one Embodiment of the gas barrier plastic container of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Gas barrier plastic container 11 ... Innermost layer 12 of container ... 1st vapor deposition thin film layer 13 ... 2nd vapor deposition thin film layer 14 ... 3rd vapor deposition thin film layer 15 ... Opening part

Claims (2)

  A first vapor-deposited thin film layer made of an organosilicon compound having a carbon atom ratio of 10 to 20% on the innermost layer surface of the plastic container, an organosilicon compound having a carbon atom ratio of less than 5% and SiOx (x = 2 to 2) .5) and a third vapor-deposited thin film layer made of an organosilicon compound having a carbon atom ratio of 10 to 20% are sequentially laminated.   2. The gas barrier plastic container according to claim 1, wherein the first vapor deposition thin film layer and the third vapor deposition thin film layer have a thickness of 10 to 100 nm, and the second vapor deposition thin film layer has a thickness of 5 to 50 nm.

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