JPH04267748A - Plastic container body and its manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic container body and a method for manufacturing the same.

0002

[Prior Art] Metal containers, such as metal cans, are used as food packaging containers for various canned foods, juices, soft drinks, jams, dried foods, etc., and are rigid containers with particularly excellent sealing and preservation functions. be. However, metal cans
There are points that need to be improved as shown below. That is, (1) Since it is a metal can, there is a limit to its weight reduction. ■ Once it is crushed by an impact, it will not recover.
It becomes deformed. ■ Compared to plastic containers, the energy cost of manufacturing them is higher. ■ If the display effect of the container exterior is made of metal, it cannot be changed freely, and the only means of exterior packaging is printing, and there is little freedom in the shape.

In order to solve these drawbacks of conventional metal cans, containers are being considered in which lids of various materials and shapes are attached to plastic container bodies. Also,
As a method of manufacturing a plastic container body, a plastic laminate having the thickness necessary for forming the container is heated using a general thermoforming method, and then a molded product of the container body with a flange is formed using a mold. There are several methods such as sheet forming, injection molding in which molten resin is poured into male and female molds, and blow molding in which molding air is blown into the parison in the mold. In order to improve the storage stability of the contents of these molded products, resins with high gas barrier properties such as ethylene vinyl alcohol copolymer (EVOH), vinylidene chloride (PV
DC, acrylonitrile-methyl acrylate copolymer, etc. are said to be effective. However, although all of these have excellent gas barrier properties, they allow a small amount of oxygen and water vapor to pass through, whereas metals and glass do not allow any oxygen or water vapor to pass through.

0004

As mentioned above, the container body is required to have a certain gas barrier property in order to protect the contents, depending on the contents, distribution period, and other conditions. At the same time, it is also necessary to consider the aesthetic appearance of the container body. The present invention has been made with these points in mind, and it is an object of the present invention to provide a container body with excellent gas barrier properties and aesthetic appearance.

[0005]

[Means for Solving the Problems] The present invention is characterized in that, in a plastic container body, an epoxy primer is applied to the outer surface of the molded product of the container body, and a metal powder is applied on the epoxy primer. a step of creating a plastic container body molded product having a flange portion at the top opening; a step of applying an epoxy primer to the outer surface of the container body molded product; This is a method for manufacturing a plastic container body, which comprises a step of low-temperature spraying metal powder in a molten state.

[0006]

[Operation] According to the present invention, metal powder below the melting point is thermally sprayed in a molten state onto the epoxy primer coated on the surface of the plastic container body molded product, so that the container body molded product is thermally deformed. It is possible to apply metal powder without causing any damage, and the amount of distortion due to solidification shrinkage after application can be kept small.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1 to 4 are diagrams showing an embodiment of a plastic container body and a method of manufacturing the same according to the present invention. First, a container body according to the present invention will be explained with reference to FIG. As shown in FIG. 1, the container body 11 includes a body 12a having an opening at the top, a bottom 12b, and a flange 13 provided around the upper opening of the body 12a and protruding radially outward. The container body 11 is constructed by applying an epoxy primer 21 as a roughening agent to the outer surface of a molded container body 25, and further applying metal powder 22 on the epoxy primer 21.

Among these, Brasnon #21 is used as the epoxy primer 21, and metal powder 2
Examples of 2 include Cu powder, Al powder, Fe powder, or Zn powder.
Powder is used. Also, the thickness of the metal powder 22 is 15 to 40u.
It becomes. The contents 19 are stored inside the container body 11 having such a structure, and the metal lid 1 is attached to the flange portion 13.
By doubly wrapping the peripheral edge 17 of 6, a container 10 with a metal lid as shown in FIG. 2 is obtained. The metal lid 16 that wraps around the container body 11 is made of Al, and its front and back surfaces are coated with a synthetic resin material.

Next, a method for manufacturing the plastic container body will be explained. First, with reference to FIG. 3, a process of thermoforming a molded product of a container body by general sheet forming will be described. That is, a laminated material 30 having a thickness necessary for forming a container is preheated by a heating machine 41, and a plurality of container body molded products 25 are formed using a mold 42. The molding method may be air pressure molding, vacuum molding, or a combination thereof. As the laminated material 30, for example, one having the following layer configuration is used. Laminated material of polypropylene (PP) layer/adhesive layer/ethylene-vinyl alcohol copolymer (EVOH) layer/adhesive layer/polypropylene (PP) layer.

Among these, the polypropylene (PP) layer has transparency, water resistance, and heat resistance, and also has ethylene-
The vinyl alcohol copolymer layer has gas barrier properties and is transparent at the same time. Further, as the adhesive layer, for example, an acid-modified polypropylene body is used.

Next, the container body molded product 25 is separated one by one, and then the thickness of the flange portion of the container body molded product is reduced (
(pressing process), and the width of the flange part of the container body molded product is set to a predetermined width (cutting process). Next, the container body molded product 25 is subjected to corona treatment to improve its wettability, and then an epoxy primer 2 such as Brasnon #21 is applied to the entire outer surface.
1 is applied as a surface roughening agent by spraying, and metal powder 22 is further applied onto the epoxy primer 21.
In this way, the container body 11 is obtained.

The metal powder 22 is applied onto the epoxy primer 21 by low-temperature spraying, and this low-temperature spraying will be explained with reference to FIG. 4. As shown in FIG. 4, the low-temperature spraying machine 45 has an injection air inlet 46 and a shield gas inlet 49 located inside the injection air inlet 46, and the discharge sides of these inlets 46 and 49 are conical. A nozzle 48 is provided. In addition, two metal welding materials 47 in the nozzle 48,
47 intersect, and an arc is generated at the tips of the weld metals 47, 47 to melt the metal weld materials 47, 47. As the metal welding material 47, 47, as mentioned above, Cu, A
1, Fe, Zn, etc. are used.

The molten metal is then heated to an air pressure of 6.5K, for example.
It is pulverized into fine particles of 5 to 150 um in g/cm2 jet air and rapidly cooled. The fine metal powder is further cooled during the distance to the container body molded product 25, reaches the container body molded product 25, becomes even lower in temperature, and is coated on the epoxy primer 21.

Immediately after the low-temperature spraying machine 45, the fine metal powder is already in a temperature range where it should be in a completely solid state;
Since the particles are given a high-speed flight motion of 200 to 220 m/sec, displacement of the deformed body occurs. Therefore, even though the metal powder is cooled to a temperature in a solid state, it remains in a liquid phase or a semi-liquid phase until immediately after colliding with the container body molded product 25. Therefore, compared to general sprayed molten metal powder, the amount of distortion due to solidification shrinkage immediately after deposition is minute.

As described above, according to this embodiment, metal powder at a low temperature below the melting point is applied to the epoxy primer 21 on the surface of the container body molded product 25 in a molten state (liquid phase or semi-liquid phase state).
The coating can be reliably applied to the container body molded product without thermally deforming it. Further, the amount of distortion due to solidification shrinkage of the molten metal after coating can be minimized, and a stable coating state can be maintained. Furthermore, the applied metal powder can improve the gas barrier properties of the container body and improve the aesthetic appearance of the container body.

Although the plastic sheet in the above embodiment includes an EVOH layer, it is not limited to the above embodiment, and may be a sheet made of polypropylene alone, for example. Further, in the above embodiment, the plastic container main body is formed by sheet molding, but the present invention is not limited to this, and plastic containers of various shapes and materials may be formed by injection molding or blow molding.

Next, a specific example of the present invention will be explained.

In a specific example, a plastic container body was thermoformed by general sheet forming and metal powder was applied onto the container body, and the following four types of container bodies were created. Next, a gas barrier property test was conducted on these container bodies.

The results are shown below.

[0021] Type
Layer structure Acidic barrier property

[20℃ 40RH%]

(cc/m2, 24h
rs, atm) ■ PP100
μ/EVOH20μ/PP100 μ
0.8 ■ P
P200μ
7
■ PP100μ/E
VOH20μ/PP100μ 0
/
Al low temperature spraying 25μ

■ PP200μ/Al low temperature spraying 25μ 0



As can be seen from this test result, A
All of the containers subjected to low-temperature spraying had good oxygen barrier properties.

[0022]

[Effects of the Invention] As explained above, according to the present invention,
Metal powder can be applied to the molded container body without causing thermal deformation, and the amount of distortion due to solidification shrinkage after application can be kept small to maintain a stable application state. Therefore, the applied metal powder can improve the gas barrier properties of the container body and also improve the aesthetic appearance of the container body.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing a container body according to the present invention.

FIG. 2 is a side sectional view showing a container with a metal lid.

FIG. 3 is a schematic system diagram showing a process of manufacturing a molded product of a container body by thermoforming by sheet forming.

FIG. 4 is a side sectional view showing a low temperature thermal spraying machine.

[Explanation of symbols]

10 Container with metal lid 11 Container body 12a Torso 12b Bottom 13 Flange part 16 Metal lid 17 Peripheral area 19 Contents 21 Epoxy primer 22 Metal powder 25 Container body molded product 45 Low temperature thermal spraying machine

Claims (2)

[Claims] 1. A plastic container body, characterized in that the outer surface of a molded container body is coated with an epoxy primer, and the epoxy primer is coated with metal powder. 2. A step of creating a plastic container body molded product, a step of applying an epoxy primer to the outer surface of the container body molded product, and a step of applying a metal powder below the melting point on the epoxy primer in a molten state. 2. The method of manufacturing a plastic container body according to claim 1, comprising the step of low-temperature thermal spraying.