JP4140357B2 - Multi-layer plastic container - Google Patents

Description

【００３０】
【発明の効果】
本発明により、積層体をブロー成形してなる、安価で、特に酸素バリア性に優れるバリア性を有する多層プラスチック容器を提供することをができる。
【図面の簡単な説明】
【図１】（ａ）は、本発明の積層体の一例を示す断面図である。
（ｂ）は、本発明の多層プラスチック容器の一例を示す模式図である。
【符号の説明】
１０・・・積層体
１・・・第１の樹脂層
２・・・第２の樹脂層
３・・・セラミック薄膜層
２０・・・多層プラスチック容器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laminate and a multilayer plastic container having a barrier property that is excellent in oxygen barrier property, and is formed by blow molding the laminate.
[0002]
[Prior art]
Recently, plastic containers have been 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 the property of permeating low-molecular gases such as oxygen, carbon dioxide, and water vapor, and the property that low-molecular organic compounds are adsorbed inside. was there.
[0003]
Various measures have been taken to solve these problems, but all have various problems and have not been completely solved. For example, as one method for reducing the gas permeability of a plastic container, there is a method of laminating or blending a plurality of plastic materials. When these methods are used, the gas permeability can be reduced to a certain extent, but it cannot be reduced to the target gas permeability such as when used in a container that requires a higher barrier property.
[0004]
Also, the cost of the resin used is very high. In recent years, a technique for coating a plastic container with a ceramic thin film has been known. Most of these films are formed on a plastic molded article made of a single material to improve the barrier property. By using this technique, a container having excellent barrier properties can be obtained at low cost by forming a container using a relatively inexpensive material and coating the surface of the container with a ceramic thin film. However, depending on the material, the ceramic thin film could not be coated or the desired barrier properties were not achieved.
[0005]
[Problems to be solved by the invention]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a multilayer plastic container having a barrier property which is low in cost and particularly excellent in oxygen barrier property, which is formed by blow molding a laminate. To do.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, that is, in the invention according to claim 1, at least the first resin layer has a melt flow rate defined in JIS K 7210 (at a test temperature of 190 ° C. and a nominal load of 2.16 kg). The first resin layer is made of polyethylene of 1 g / 10 min to 10 g / 10 min, and the second resin layer is formed by blow molding a laminate made of polyethylene having a melt flow rate of 0.5 g / 10 min or less. A container in which the inner layer surface and the second resin layer form the outer layer surface, and a ceramic thin film layer made of a silicon oxide thin film or diamond-like carbon is coated on the inner surface side of the first resin layer by a CVD deposition method. A multilayer plastic container characterized by the above.
[0007]
The invention according to claim 2 is a multilayer plastic container of claim 1, wherein the thickness of the first resin layer having a pre-Symbol polyethylene is 5μm or more.
[0008]
The invention according to claim 3 is the multilayer plastic container according to claim 1 or 2, wherein the polyethylene of the first resin layer is linear polyethylene.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment as an example of the present invention will be described with reference to the drawings. Fig.1 (a) is sectional drawing which shows an example of a structure of the laminated body used by this invention.
As shown in FIG. 1 (a), the laminate used in the present invention is at least a laminate comprising a first resin layer 1 and a second resin layer 2, and the first resin layer 1 is JIS K. The melt flow rate specified in 7210 (at a test temperature of 190 ° C. and a nominal load of 2.16 kg) is made of polyethylene of 1 g / 10 min to 10 g / 10 min .
If the melt flow rate exceeds 10 g / 10 min , the resin will be drawn down during molding. On the other hand, if the melt flow rate is less than 1, flow disturbance occurs on the surface of the first resin layer at the time of molding, the smoothness is impaired, and it is unsuitable as a film formation surface.
[0015]
In the present invention, the thickness of the layer made of polyethylene is preferably 5 μm or more in order to eliminate the influence of adhesion to the second resin layer.
[0016]
The polyethylene in the present invention is preferably a linear polyethylene.
[0017]
The second resin layer in the present invention is polyethylene having a melt flow rate of 0.5 g / 10 min or less.
[0018]
As shown in FIG. 1 (b), the multilayer body obtained above is subjected to a multilayer blow molding technique that is generally used, and the first resin layer 1 is the inner layer surface and the second resin layer 2 is After forming into a multilayer plastic container so as to form the outer layer surface, the multilayer plastic container of the present invention in which the ceramic thin film layer 3 is formed on the inner surface side of the first resin layer 1 can be manufactured.
Since the ceramic thin film layer is not affected by the type of the second resin layer, the material of the second resin layer is not particularly limited, and a multilayer plastic container having a barrier property excellent in oxygen barrier property can be obtained.
[0019]
As a method of forming the ceramic thin film layer on the inner layer surface composed of the first resin layer, it is desirable to use the plasma CVD method because the ceramic thin film can be uniformly coated on the surface of the three-dimensional container. In addition, an evaporation method, a sputtering method, or the like can also be used.
[0020]
The material and thickness of the ceramic thin film layer are not limited, but a silicon oxide film or a diamond-like carbon film is particularly desirable because high barrier properties can be obtained and coating can be performed relatively easily. The thickness is preferably set to 10 nm or more and 100 nm or less.
[0021]
【Example】
Examples of the present invention will be specifically described below.
[0022]
<Example 1>
A polyethylene resin having a melt flow rate of 0.3 g / 10 min is used as the second resin layer, and a polyethylene having a melt flow rate of 1.6 g / 10 min is used as the first resin layer. Molded by blow molding. The minimum thickness of the inner layer made of the first resin layer was 10 μm. A silicon oxide thin film having a film thickness of about 40 nm was coated on the inner surface of the container using a plasma CVD method. Table 1 shows the oxygen barrier property data of the obtained container.
[0023]
<Example 2>
A polyethylene resin having a melt flow rate of 0.3 g / 10 min is used as the second resin layer, and a polyethylene having a melt flow rate of 4.5 g / 10 min is used as the first resin layer. Molded by blow molding. The minimum thickness of the inner layer made of the first resin layer was 10 μm. A silicon oxide thin film having a film thickness of about 40 nm was coated on the inner surface of the container using a plasma CVD method. Table 1 shows the oxygen barrier property data of the obtained container.
[0024]
<Example 3>
A polyethylene resin having a melt flow rate of 0.3 g / 10 min is used as the second resin layer, a polyethylene having a melt flow rate of 7.3 g / 10 min is used as the first resin layer, and a multilayer plastic container having an internal volume of 500 ml is used. Molded by blow molding. The minimum thickness of the inner layer made of the first resin layer was 10 μm. A silicon oxide thin film having a film thickness of about 40 nm was coated on the inner surface of the container using a plasma CVD method. Table 1 shows the oxygen barrier property data of the obtained container.
[0025]
<Example 4>
The inner surface of a multilayer plastic container similar to that in Example 1 was coated with diamond-like carbon having a film thickness of about 50 nm using the plasma CVD method. Table 1 shows the oxygen barrier property data of the obtained container.
[0026]
<Comparative Example 1>
The oxygen barrier property of a bottle in which a ceramic thin film layer was not provided on the inner surface of the same multilayer plastic container as in Example 1 was measured. The data is shown in Table 1.
[0027]
<Comparative Example 2>
Using polyethylene melt flow rate 0.3 g / 10min as the second resin layer, using polyethylene melt flow rate 0.3 g / 10min to the first resin layer, a multilayer plastic container having an inner volume of 500ml Molded by blow molding. The minimum thickness of the inner layer made of the first resin layer was 10 μm. A silicon oxide thin film having a film thickness of about 40 nm was coated on the inner surface of the container using a plasma CVD method. Table 1 shows the oxygen barrier property data of the obtained container.
[0028]
<Comparative Example 3>
A polyethylene resin with a melt flow rate of 0.3 g / 10 min is used as the second resin layer, a polyethylene with a melt flow rate of 15 g / 10 min is used as the first resin layer, and a multilayer plastic container having an internal volume of 500 ml is blow-molded. Was molded by. The minimum thickness of the inner layer made of the first resin layer was 10 μm. A silicon oxide thin film having a film thickness of about 40 nm was coated on the inner surface of the container using a plasma CVD method. Table 1 shows the oxygen barrier property data of the obtained container.
[0029]
[Table 1]

[0030]
【The invention's effect】
According to the present invention, it is possible to provide an inexpensive multilayer plastic container having a barrier property which is low in cost and particularly excellent in oxygen barrier property, which is obtained by blow molding a laminate.
[Brief description of the drawings]
FIG. 1A is a cross-sectional view showing an example of a laminate of the present invention.
(B) is a schematic diagram which shows an example of the multilayer plastic container of this invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Laminated body 1 ... 1st resin layer 2 ... 2nd resin layer 3 ... Ceramic thin film layer 20 ... Multilayer plastic container

Claims (3)

At least the first resin layer is made of polyethylene having a melt flow rate specified in JIS K 7210 (at a test temperature of 190 ° C. and a nominal load of 2.16 kg) of 1 g / 10 min to 10 g / 10 min, The resin layer is a container formed by blow molding a polyethylene laminate having a melt flow rate of 0.5 g / 10 min or less, wherein the first resin layer forms the inner layer surface and the second resin layer forms the outer layer surface. A multilayer plastic container, wherein a ceramic thin film layer made of a silicon oxide thin film or diamond-like carbon is coated on the inner surface side of the first resin layer by a CVD deposition method . Multilayer plastic container of claim 1, wherein the thickness of the first resin layer having a pre-Symbol polyethylene and wherein the at 5μm or more. The multilayer plastic container according to claim 1 or 2, wherein the polyethylene of the first resin layer is a linear polyethylene.

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