JPH04267747A - plastic container - Google Patents

Abstract

PURPOSE:To prevent contents from adhering to the inner surface of a container or flavor from adsorbing thereon by a method wherein the container is formed mainly of plastic or film having its surface covered with a thin silicon oxide film and fabricated with the thin silicon oxide film side positioning on the inner surface thereof. CONSTITUTION:As the resin material for plastic sheet or film, polyethylene, polypropylene, polyester, etc., are used in the form of a thin SO film 1. From the economical viewpoint, however, it is preferable to metallize silicon dioxide, silicon monoxide or a mixture thereof under vacuum. In a case where the plastic sheet or film covered with the thin SO film is used with the other plastic sheet 2, after the non-SO film sides are layered using an adhesive agent 5, the adhesive agent is applied to only the bonding areas required for container fabrication, the peripheral parts are cut off, the plastic materials are fabricated into the form of a container with the thin SO film sides inward and the joined parts 6 are thereafter subjected to thermocompression bonding.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic container, and more particularly to a plastic container whose inner surface is coated with a vitreous thin film.

0002

[Prior art] Plastic containers are lightweight, unbreakable,
It is widely used in place of glass and metal containers due to its many advantages, such as not rusting. However, depending on the type of plastic container, the contents may adhere to the inner surface of the container, making it difficult to remove the contents when the container is opened.

[0003] Furthermore, in the case of plastic containers, the flavor of the contents may be adsorbed by the container, or plastic odor or additives such as plasticizers may be transferred from the container to the contents, which may impair the quality of the contents. Furthermore, due to the lack of gas barrier properties of the container, the quality of the contents may be impaired due to oxidation of the contents or volatilization of moisture in the contents.

Conventionally, in order to deal with the above-mentioned problems, efforts have been made to select and use different plastic materials for containers depending on the type of contents and the intended use of the container. In addition, in order to maintain the quality of the contents and increase their shelf life,
Efforts have also been made to combine plastic materials. For example, a typical method is dry plating a metal such as aluminum or a compound of a metal such as aluminum, magnesium, or silicon with oxygen or nitrogen on the outside of a plastic container in order to improve gas barrier properties.

[0005]

[Problems to be Solved by the Invention] However, although the method of dry plating an inorganic substance on the outside of a plastic container as described above is effective in preventing oxidation of the contents and prevention of moisture volatilization, It cannot be used as a countermeasure against the problems of adhesion and flavor adsorption.

[0006]

[Means for Solving the Problems] In view of the above-mentioned circumstances, the present inventors have made extensive studies and have found that a container whose inner surface is coated with a glassy silicon oxide thin film has excellent gas barrier properties. The present invention has been completed based on the findings that not only is the content of the container less likely to adhere to the inner surface of the container, but also the adsorption of flavor to the inner surface of the container is less.

That is, the gist of the present invention is that the surface has a thickness of 1
The present invention relates to a plastic container mainly composed of a plastic sheet or film coated with a silicon oxide thin film having a thickness of 00 to 3,000 Å, and formed so that the silicon oxide thin film is located on the inner surface.

The present invention will be explained in detail below. First, the plastic sheet or film will be explained. As the plastic, any of the various plastics currently used for plastic containers can be used without restriction. Specifically, polyethylene, polypropylene,
Examples include polyester-based, polystyrene-based, polycarbonate-based, and nylon-based resins. The plastic sheet or film may be a single plastic material, or may be a composite material with other plastics, paper, aluminum, etc.

In particular, heat-set biaxially oriented polyethylene terephthalate film has excellent strength, thermal properties, safety,
It is advantageous in terms of cost and also has the advantage of being easy to form a silicon oxide thin film, which will be described later, and is therefore preferably used. It is advantageous to use a relatively thin polyethylene terephthalate film and laminate the opposite side of the silicon oxide thin film with another plastic sheet, film, or cardboard.

Next, a silicon oxide thin film (SO thin film) will be explained. The above-mentioned plastic sheet and the like are used after being coated with an SO thin film. Conventionally known thin film forming techniques such as vacuum evaporation, sputtering, and ion plating can be used to form an SO thin film on the surface of a plastic sheet, etc. However, from an economical point of view, silicon dioxide, silicon monoxide, etc. Alternatively, vacuum deposition is suitable, in which a mixture of these is deposited on a plastic sheet or the like in a vacuum.

[0011] The thickness of the SO thin film is 100 to 3,000 Å.
It needs to be within the range of If the thickness of the SO thin film is less than 100 Å, the gas barrier performance is insufficient;
If it exceeds 000 Å, it is not practical because the film may curl, which may cause problems, or the SO thin film itself may easily crack or peel.

[0012] Prior to forming the SO thin film, it is also possible to use an anchor coating agent in order to increase the adhesive strength between the thin films. Suitable anchor coating agents include isocyanate-based, polyethyleneimine-based, organic titanium-based adhesion promoters, and polyurethane-based, polyester-based adhesives. Further, as the anchor coating agent, a solvent-free type adhesive such as polyethylene, polyester, or polyamide may be used.

[0013] Note that the SO thin film may contain calcium, magnesium, or oxides thereof as impurities, as long as the amount is 10% by weight or less.

Next, a method for manufacturing the container will be explained. The plastic container of the present invention can be manufactured according to conventionally known methods commonly used for paper containers and the like. In other words, when using a plastic sheet or film coated with an SO thin film together with another plastic sheet, the non-SO thin film side of the former and the latter are laminated with an adhesive, and then the container is assembled. It is manufactured by applying adhesive only to the parts to be joined, cutting out the peripheral part, shaping it into a container with the SO thin film side facing inside, and then heat-pressing the joint parts.

[0015] Conventionally known general adhesives such as urethane adhesives and acrylic adhesives can be used as the above adhesive, but hot melt adhesives such as modified polyolefin adhesives, polyester adhesives, and polyamide adhesives may also be used. A film adhesive of these resins can also be used.

Next, the form of the container of the present invention will be explained using schematic diagrams. 1 is a schematic plan view of a three-sided sealed bag, FIG. 2 is an enlarged cross-sectional view taken along line X-X' in FIG. 1, FIG. 3 is a schematic side view of a cylindrical container, and FIG. 4 is a cylindrical container shown in FIG. 3. A schematic plan view of
FIG. 5 is an enlarged view of the YY' cross section of FIG.

[0017] The three-side sealed bag shown in Figs.
A cardboard (3) was laminated on the non-SO thin film side of the polyethylene terephthalate film (2) coated with the thin film (1) via an adhesive (5), and a polyethylene film (4) was laminated on the surface of the cardboard. Composite film is used. Then, two sheets of this composite film were used, and they were laminated so that each SO thin film (1) was on the inner surface, and the three ends were heat-pressed with the bonding layer (6) interposed therebetween.

The cylindrical container shown in FIGS. 3-5 uses a polyethylene terephthalate film (2) coated with a SO thin film (1). Then, this polyethylene terephthalate film was formed into a cylindrical shape with the SO thin film (1) on the inner surface, and both ends of the film were overlapped and heated and pressed through the bonding layer (6). The other parts were also heat-pressed in the same way.

[0019]

EXAMPLES The present invention will be explained in more detail with reference to examples below, but the present invention is not limited to the following examples unless it exceeds the gist thereof. In addition, in the following examples, the containers were evaluated by the following methods. Further, the structure of the container and the evaluation results are summarized in Tables 1 and 2.

<Oxygen permeability (cc/m2, 24H, atm)> Oxygen permeability of the film forming the container was measured using a UX-TRAN100 type oxygen permeability measuring device manufactured by Modern Control Co., Ltd. at a temperature of 30° C. Measurements were made under conditions of 80% humidity.

<Adhesion of contents> Commercially available tomato ketchup was filled and sealed in a three-sided sealed bag, and the bag was heated at 40°C x 90% RH.
After storage for 200 hours under these conditions, one side of the bag was opened and the bag was hung upside down to allow the contents to fall out of the bag. The amount of tomato ketchup remaining in the bag after 10 minutes was determined from the ratio to the initial filling amount.

<Change in flavor of contents> In evaluating the adhesiveness of the contents described above, a sensitivity test was conducted on tomato ketchup taken out from the bag to determine changes in flavor during storage.

<Change in the color of the contents> When evaluating the adhesiveness of the contents described above, the color of the tomato ketchup immediately before opening after storage was compared with the original sample, and the change in the color of the contents due to oxygen was judged with the naked eye. did.

[0024] The above-mentioned changes in the flavor of the contents and changes in the color of the contents were evaluated according to the following criteria. ○ Almost no change △ Change × Significant change

Examples 1 to 3 An SO thin film was formed on one side of an unstretched polypropylene film (thickness: 40 μm) to the thickness shown in Table 1 by vacuum evaporation, and then an SO thin film was formed on the opposite side of the SO thin film. , biaxially oriented polyethylene terephthalate film (thickness 2
5μ) was laminated to obtain a laminate film. Two films of 70 mm x 10 mm in size were cut out from the above laminated film, and with the SO thin film side on the inside, a 10 mm width around the three sides was thermally bonded via an adhesive polyolefin resin film (APO manufactured by Mitsubishi Kasei). 50mm x 10
A 0 mm three-sided sealed bag was created.

Example 4 Biaxially oriented polyethylene terephthalate film (thickness 2
A SO thin film was formed on one side of the 5μ) by vacuum evaporation method to the thickness shown in Table 1, and a 50 mm x 100 mm three-sided sealed bag was created in the same manner as in Example 1, with the SO thin film side on the inside. did.

Comparative Example 1 A biaxially stretched polyethylene terephthalate film (thickness 25 μm) was laminated on one side of an unstretched polypropylene film (thickness 40 μm) via an adhesive to obtain a laminate film. From the above laminated film, 70mm x
Cut out two 10mm-sized films, put the unstretched polypropylene film side inside, and heat-bond 10mm widths on three sides with an adhesive polyolefin resin film (APO manufactured by Mitsubishi Kasei) to form a 50mm x 100mm three piece.
I made a sticker bag.

Comparative Example 2 A three-sided sealed bag was prepared in the same manner as in Example 1, except that the thickness of the SO thin film was changed to 50 Å.

Comparative Example 3 After forming an SO thin film on one side of an unstretched polypropylene film (thickness 40μ) by vacuum evaporation method to the thickness shown in Table 1, an adhesive was applied to the side of the SO thin film. Biaxially stretched polyethylene terephthalate film (thickness 25μ
) were laminated to obtain a laminate film. Cut out two films of 70 mm x 10 mm from the above laminated film, place the polypropylene film side inside, and insert adhesive polyolefin resin film (Mitsubishi Kasei A
PO), heat-bond the 10mm width on three sides, and
A three-sided sealed bag measuring mm x 100 mm was prepared.

[0030]

[Table 1] PET: Biaxially oriented polyethylene terephthalate film CPP: Unoriented polypropylene film SO: Silicon oxide thin film

[0031]

[Table 2]

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view of a three-sided seal bag of the present invention.

FIG. 2 is an enlarged cross-sectional view taken along line XX' in FIG. 1;

FIG. 3 is a schematic plan view of the cylindrical container of the present invention.

FIG. 4 is a schematic plan view of the cylindrical container shown in FIG. 3;

FIG. 5 is an enlarged view of the YY' cross section in FIG. 3;

[Explanation of symbols]

1...Silicon oxide thin film 2...Polyethylene terephthalate film 3
・・・・・・Thick paper 4・・・Polyethylene film 5・・・Adhesive

Claims (1)

[Claims] Claim 1: Mainly composed of a plastic sheet or film whose surface is coated with a silicon oxide thin film with a thickness of 100 to 3,000 Å, and the silicon oxide thin film is located on the inner surface. A plastic container featuring: