JP2002080025A - Gas barrier container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas barrier container having stable gas barrier properties at a low cost without using a plastic and without providing a sealing layer on the container. SOLUTION: The gas barrier container is formed of a pulp-molded base material whose gas transmission rate measured according to JIS P8117 is at least 60 seconds and/or whose smoothness measured according to JIS P8119 is at least 2 seconds, and whose surface is provided with a thin film formed by plasma polymerization.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas barrier container having stable gas barrier properties.

[0002]

2. Description of the Related Art In recent years, as environmental problems have increased, paper containers have begun to be widely used in fields where plastic containers and metal containers are mainly used, for example, in the fields of toiletry-related products, beverages and foods. I have. For example, in the field of milk containers and the like, paper containers in which polyethylene paper is coated on both sides of paper and formed into an octahedral container or a roof-type container called a gable top have already been generally used. However, since the paper container as described above is formed by bending and bonding paperboard,
There is no flexibility in the shape, and it is difficult to fully express the uniqueness of the product.

[0003] One means for giving a paper container a degree of freedom is a pulp mold. A pulp mold container made of this pulp mold is generally manufactured by sucking and dewatering a pulp material on a papermaking mold by a wet method, and then drying it in a drying furnace or a heating mold. Also, especially dimensional stability,
When aesthetics are required, the pulp can be produced by suction-dehydrating pulp on a papermaking mold, and then heating and drying in a press mold that fits each other. Furthermore, according to the manufacturing method described in JP-A-11-314267, a hollow shape such as a bottle shape can be molded. The pulp mold container manufactured in this way has a high degree of freedom in shape and does not have a bonded portion, so that a high value-added product can be provided.

[0004] However, these pulp mold containers are:
Basically, since the constituent material is pulp, there are problems that the water resistance and the water vapor barrier property are poor, the strength of the container is reduced due to moisture absorption, and the quality of the contents cannot be maintained.
For example, if the water vapor barrier property is poor, there arises a problem that the content of the powder in the container absorbs moisture and causes deterioration in quality.

When a gas barrier property against water vapor, oxygen, etc. is required to maintain the quality of the contents, the pulp mold container obtained as described above has a complicated gas barrier layer due to its complicated three-dimensional shape. Has become difficult. As means for improving these problems, Japanese Patent Application Laid-Open
JP-A-218152 and JP-A-10-218235 disclose that a plastic sheet is vacuum-pressure-molded on a pulp mold container.
Japanese Patent Laid-Open Publication No. 2000-214, discloses that a plastic parison is stretch-blown on the inner surface of a pulp mold container and is compounded with plastic, but there is a problem that the manufacturing process is complicated and the manufacturing cost is increased. The concept does not fit into the concept considering environmental issues.

[0006] Therefore, we have filed Japanese Patent Application No. 2000-102600.
A pulp mold container as shown in the specification of JP-A No. 1993/1990, in which a thin film is formed by plasma polymerization on the surface of a pulp mold substrate of the container, has been developed. The pulp mold container has excellent gas barrier properties and hardly uses plastic.

However, the pulp mold base material is originally a porous and non-uniform structure obtained by collecting and drying pulp fibers as described above. If a thin film is formed directly on the surface by plasma polymerization, defects such as pinholes are formed. Easily occur,
There was a tendency that the quality of the gas barrier properties was difficult to stabilize. Conventionally, a resin layer was interposed to seal the surface of the porous pulp mold member.However, a process of coating the resin layer on the surface of the three-dimensional pulp mold was required, resulting in a large cost increase. Was.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and is intended to provide a gas-barrier container having a stable gas-barrier property without using plastic and providing a sealing layer. It is intended to be provided without any cost.

[0009]

Means for Solving the Problems The present invention has been made to achieve the above object, and the gas barrier container according to claim 1 is a container mainly composed of a pulp mold substrate. The pulp mold substrate is JIS P81
The air permeability measured in accordance with No. 17 is 60 seconds or more, and a thin film is formed on the surface by plasma polymerization.

The gas barrier container according to claim 2 is a container mainly composed of a pulp mold base material, and the pulp mold base material has a smoothness of 2 seconds or more measured according to JIS P8119. A thin film is formed on the surface by plasma polymerization.

Further, in the gas barrier container according to the third aspect, the pulp mold base material has an air permeability measured in accordance with JIS P8117 of 60 seconds or more, and JIS P811.
The smoothness measured according to No. 9 is 2 seconds or more, and a thin film is formed on the surface by plasma polymerization.

[0012] The gas barrier container according to claim 4 is the gas barrier container according to any one of claims 1 to 3, wherein the pulp mold substrate is formed at the time of molding.
Alternatively, after molding, in a mold with a smooth surface, 0.5 MPa
It is characterized by being pressed under the above pressure.

According to a fifth aspect of the present invention, there is provided the gas barrier container according to any one of the first to fourth aspects, wherein the pulp mold base material has at least a pulp material of a surface layer portion thereof according to JIS P8121. Freeness measured according to Canadian standard freeness test method is 200c
sf or less.

According to a sixth aspect of the present invention, there is provided the gas barrier container according to any one of the first to fifth aspects, wherein the pulp mold substrate comprises at least a pulp material of a surface layer portion thereof, and a fine pulp. Is included.

The gas barrier container according to claim 7 is the gas barrier container according to any one of claims 1 to 6, wherein the pulp mold base material has at least a pulp material in a surface layer portion of an alkoxysilane. It is characterized in that an internal additive mainly composed of a decomposition product is internally added.

The gas barrier container according to claim 8 is characterized in that, in the gas barrier container according to any one of claims 1 to 7, the pulp mold substrate is made of a multilayer paper.

According to a ninth aspect of the present invention, in the gas barrier container according to the first to eighth aspects, the thin film formed by the plasma polymerization is an organic silica thin film. .

According to a tenth aspect of the present invention, in the gas barrier container according to the ninth aspect, the ratio of carbon atoms contained in the thin film formed by the plasma polymerization is 5% or more. And

The gas barrier container according to claim 11 is characterized in that, in the gas barrier container according to any one of claims 1 to 8, the thin film formed by the plasma polymerization is a carbon-based thin film.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory sectional view showing one embodiment of the gas barrier container of the present invention. This container (1) is basically composed mainly of a pulp mold substrate (2), and a thin film (3) is formed on the surface thereof by plasma polymerization.

The pulp mold substrate (2) has a surface with a dense surface layer, high air permeability, and high smoothness. More specifically, the air permeability measured according to JIS P8117 is 60 seconds or more, or JIS P811
9 has a smoothness of 2 seconds or more, or an air permeability of 60 measured according to JIS P8117.
A base material characterized by having a smoothness of at least 2 seconds, measured in accordance with JIS P8119, for at least 2 seconds. The material and molding method of the pulp material are not limited as long as the pulp mold base material (2) applicable to the present invention satisfies the above characteristics. Also, the shape is not particularly limited as long as it is a shape such as a tray, a bowl, a bottle, or the like that can be pulp molded.

Further, the gas barrier container of the present invention (1)
Is characterized in that a thin film (3) formed by direct plasma polymerization is formed on the surface of a pulp mold substrate (2) having a dense surface layer and a smooth surface having the above-mentioned characteristics. . This thin layer (3) can impart gas barrier properties to a pulp mold container that originally has no gas barrier properties. The gas barrier container (1) having excellent gas barrier properties of the present invention has a smooth surface and a dense surface layer of the pulp mold base material (2). Even so, stable gas barrier properties can be imparted without generating defects such as pinholes. Therefore, since the step of applying and drying the filling layer is omitted, it can be manufactured at low cost.

There are no particular restrictions on the constituent materials of the thin layer formed by the above-mentioned plasma polymerization.
There are fluorine type and carbon type. Among them, the organic silica system is
It is particularly preferable because the film formation rate by plasma polymerization is high and relatively easy. Further, by setting the ratio of carbon atoms contained in the organic silica-based thin film to 5% or more, the permeability of water vapor passing through the film can be reduced.

The monomers used for forming the organic silica-based thin film include 1,1,3,3-tetramethyldisiloxane, hexamethyldisiloxane, vinyltrimethylsilane, methyltrimethoxysilane, hexamethyldisilane, methylsilane, Dimethylsilane, trimethylsilane, diethylsilane, propylsilane, phenylsilane, vinyltriethoxysilane, vinyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, octamethylcyclotetrasiloxane, etc. Among them, 1,1,3,3-tetramethyldisiloxane, hexamethyldisiloxane and octamethylcyclotetrasiloxane are particularly preferable. However, the present invention is not limited to these, and aminosilane, silazane, or the like can be used.
A gas having an oxidizing power such as oxygen, carbon dioxide, etc.
A mixture with a rare gas such as argon or helium is used.

A carbon-based thin film is particularly preferable because of its excellent chemical resistance against alkalis and the like. Examples of monomers used for polymerizing a carbon-based thin film include alkanes such as methane, ethane, propane, butane, pentane and hexane; alkenes such as ethylene, propylene, butene, pentene and butadiene; and alkynes such as acetylene. Including aromatic hydrocarbons such as benzene, toluene, xylene and naphthalene, cycloparaffins such as cyclopropane and cyclohexane, cycloolefins such as cyclopentene and cyclohexene, carbon monoxide, carbon dioxide, methyl alcohol and ethyl alcohol. Oxygen carbon compounds, nitrogen-containing carbon compounds such as methylamine, ethylamine and aniline can be used. These gases may be used alone, or may be used as a mixture with a rare gas such as argon or helium.

The surface on which the thin film is formed is the inner surface of the container,
Either the outer surface or both surfaces may be used.

[0028]

The gas barrier container of the present invention will be described in detail with reference to the following examples.

Example 1 LBKP was beaten to 350 csf to obtain a 0.4% pulp slurry. 4 L of this pulp slurry is suction-dehydrated on a female mold to obtain a mold intermediate, which is heated and dried in a press mold fitted to each other to form a pulp mold made of a pulp mold base material as shown in FIG. The container (4) was obtained. At this time, the press mold
A suction hole was provided on the female mold side, the surface of the male mold was smooth, the mold temperature was 160 ° C., the press pressure was 0.5 MPa, and the press time was 30 seconds. The sample sampled from the bottom and side of this pulp mold container (4) was JIS
The air permeability was measured according to P8117, and JIS P811
According to No. 9, the smoothness on the inner surface side was measured. Table 1 shows the average values.

A gas barrier container of the present invention was obtained by forming an organic silicone thin film having a thickness of 400 nm on the surface of the pulp mold container by plasma polymerization using hexamethyldisiloxane as a monomer. Table 1 shows the water vapor permeability when this container was filled with 300 g of calcium chloride, the container opening was sealed with a laminated film containing aluminum foil, and the container was stored in an environment of 40 ° C. and 90% RH.

<Example 2> A pulp mold container was prepared in the same manner as in Example 1 except that the press pressure under the pulp mold molding conditions of Example 1 was changed to 0.3 MPa. The pulp mold container is humidified to a moisture content of 30% by exposing the pulp mold container to a steam mist.
The pressing was performed again at a temperature of 0.6 ° C., a pressure of 0.6 MPa, and a pressing time of 10 seconds. The samples sampled from the bottom and sides of this pulp mold container were subjected to JIS P8
The air permeability was measured according to H.117, and the smoothness of the inner surface and the outer surface was measured according to JIS P8119. Table 1 shows the average values.

An organic silicone thin film was provided on the surface of the pulp mold container by plasma polymerization in the same manner as in Example 1 to obtain a gas barrier container of the present invention. This container was filled with 300 g of calcium chloride, and the container opening was sealed with a laminated film containing aluminum foil.
Table 1 shows the water vapor permeability when stored in an RH environment.

Example 3 LBKP was beaten to 350 csf to obtain a 0.4% pulp slurry. To 4 L of this pulp slurry, N- (2-aminoethyl) -3-
Aminopropyltrimethoxysilane (Sila Ace S3
20 made by Chisso) and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane (Silaace S53
20 ml of an internal additive obtained by mixing isopropyl alcohol and water at a molar ratio of 1/4/80/80, and adding 20 ml of an internal additive.
A pulp mold container was obtained in the same manner as in Example 1 except that the pressure was 3 MPa. About the sample sampled from the bottom and side of this pulp mold container, JISP
The air permeability was measured according to 8117, and the air permeability was measured according to JIS P8119.
Was measured for the smoothness on the inner surface side. Table 1 shows the average values.

An organic silicone thin film was provided on the surface of the pulp mold container by plasma polymerization in the same manner as in Example 1 to obtain a gas barrier container of the present invention. This container was filled with 300 g of calcium chloride, and the container opening was closed with a laminated film containing aluminum foil.
Table 1 shows the water vapor permeability when stored in an environment of% RH.

Example 4 LBKP was beaten to 350 csf and 200 csf to obtain pulp slurries each having a concentration of 0.4%. First, 3 liters of pulp slurry of 350 csf is suction-dehydrated on a female mold, and then continuously dried for 20 minutes.
One liter of the pulp slurry of 0 csf was supplied onto a female mold and subjected to suction dehydration to obtain a mold intermediate. Less than,
A pulp mold container was obtained in the same manner as in Example 1 except that the pressing pressure was changed to 0.3 MPa. For the sample sampled from the bottom and sides of this pulp mold container, the air permeability was measured according to JIS P8117,
The smoothness on the inner surface side was measured according to IS P8119.
Table 1 shows the average values.

An organic silicone thin film was provided on the surface of the pulp mold container by plasma polymerization in the same manner as in Example 1 to obtain a gas barrier container of the present invention. This container was filled with 300 g of calcium chloride, and the container opening was sealed with a laminated film containing aluminum foil.
Table 1 shows the water vapor permeability when stored in an RH environment.

<Embodiment 5> In Embodiment 4 described above, 20
Instead of the pulp slurry of 0 csf, a 0.4% slurry of LBKP beaten to 350 csf was added with microfibrillated cellulose having an average fiber length of 0.13 mm (hereinafter abbreviated as MFC manufactured by specialty papermaking) in an absolutely dry pulp weight of 2%.
A pulp mold container was obtained in the same manner as in Example 4 except that the pulp slurry to which 0% was added was used, ie, two layers of LBKP having 350 csf and LBKP to which MFC had been added. The samples sampled from the bottom and sides of this pulp mold container were subjected to JIS P81
The air permeability was measured according to No. 17, and the smoothness on the inner surface side was measured according to JIS P8119. Table 1 shows the average values.

An organic silicone thin film was provided on the surface of the pulp mold container by plasma polymerization in the same manner as in Example 1 to obtain a gas barrier container of the present invention. This container was filled with 300 g of calcium chloride, and the container opening was sealed with a laminated film containing aluminum foil.
Table 1 shows the water vapor permeability when stored in an RH environment.

<Example 6> A pulp mold container was prepared in the same manner as in Example 1 above, and a carbon-based thin film having a thickness of 400 nm was formed on the surface of the pulp mold container by plasma polymerization using acetylene gas as a monomer. Was provided. This container was filled with 300 g of calcium chloride, and the opening of the container was sealed with a laminated film containing aluminum foil.
Table 1 shows the water vapor permeability when stored in an environment of 0 ° C. and 90% RH.

<Comparative Example 1> A pulp mold container was prepared in the same manner as in Example 1 except that the pressing pressure under the pulp molding conditions of Example 1 was changed to 0.3 MPa. For the sample sampled from the bottom and sides of the pulp mold container, the air permeability was measured according to JIS P8117, and the smoothness on the inner surface side was measured according to JIS P8119. Table 1 shows the average values.

An organic silicone thin film was provided on the surface of this pulp mold container by plasma polymerization in the same manner as in Example 1. Table 1 shows the water vapor permeability when this container was filled with 300 g of calcium chloride, the container opening was sealed with a laminated film containing aluminum foil, and the container was stored in an environment of 40 ° C. and 90% RH.

[0042]

[Table 1]

[0043]

As described above, in the gas barrier container according to the present invention, since the pulp mold base material is dense and the surface is smooth, a thin film obtained by direct plasma polymerization without a sealing layer is provided. Even if formed, stable gas barrier properties can be obtained. Also, by performing pulp molding by multilayer paper making as shown in Examples 4 and 5, it is possible to minimize the amount of expensive materials used and to minimize the papermaking time. However, it is possible to provide a container having excellent gas barrier properties at a lower cost without using plastic, and it is also possible to apply the present invention to a field where a plastic container or the like is conventionally used.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view of a container showing one embodiment of the present invention.

FIG. 2 is an explanatory sectional view of a pulp mold container made of a pulp mold substrate.

[Description of Signs] 1 Gas barrier container 2 Pulp mold base material 3 Thin film 4 Pulp mold container

Claims (11)

[Claims] 1. A container mainly composed of a pulp mold base material, the pulp mold base material having an air permeability of at least 60 seconds measured according to JISP8117, and a thin film formed by plasma polymerization on its surface. A gas barrier container characterized by the above-mentioned. 2. A container mainly composed of a pulp mold substrate, wherein the pulp mold substrate has a smoothness of at least 2 seconds measured according to JIS P8119, and a thin film formed by plasma polymerization on the surface thereof. A gas barrier container characterized by the above-mentioned. 3. A container mainly comprising a pulp mold base material, wherein the pulp mold base material has an air permeability of 60 seconds or more measured in accordance with JIS P8117 and JIS P8.
119. A gas barrier container characterized by having a smoothness of at least 2 seconds measured according to 119, and a thin film formed on the surface by plasma polymerization. 4. The pulp mold base material is pressed at a pressure of 0.5 MPa or more in a mold having a smooth surface at the time of molding or after molding. 4. The gas barrier container according to any one of 3. 5. The pulp mold base material has at least a pulp material of a surface layer portion having a freeness of 200 cs as measured according to a Canadian standard freeness test method of JIS P8121.
The gas barrier container according to any one of claims 1 to 4, wherein f is equal to or less than f. 6. The gas barrier container according to claim 1, wherein the pulp mold base material contains at least a pulverized pulp in a pulp material of a surface layer portion thereof. 7. The pulp mold base material according to claim 1, wherein at least the surface layer of the pulp material has an internal additive containing a hydrolyzate of alkoxysilane as a main component. 7. The gas barrier container according to any one of 6. 8. The gas barrier container according to claim 1, wherein the pulp mold substrate is made of a multilayer paper. 9. The gas barrier container according to claim 1, wherein the thin film formed by the plasma polymerization is an organic silica thin film. 10. The gas barrier container according to claim 9, wherein the ratio of carbon atoms contained in the thin film formed by the plasma polymerization is 5% or more. 11. The gas barrier container according to claim 1, wherein the thin film formed by the plasma polymerization is a carbon-based thin film.