JPH0341053B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing containers for storing foods, medicines, etc., and particularly to prevent foreign objects from entering the container before the contents are stored. The present invention relates to a method for manufacturing a hollow container that is sealed to prevent the occurrence of air leakage.

[Conventional technology]

The above-mentioned hollow containers are blown to prevent foreign matter such as dust from entering the hollow containers during transportation or storage, or to prevent deformation or damage to the original three-dimensional shape of the hollow containers. The blow hole formed by the nozzle is closed to form a sealed hollow container.

Conventionally, methods for obtaining this airtight hollow container include a method of sealing the container by moving the parison near the blow hole in the mold during blow molding, as shown in Japanese Patent Publication No. 52-45341; There are two methods: after molding, a separate member is attached to the blow hole formed by the blow nozzle to seal it.

[Problem that the invention seeks to solve]

As described above, in all conventional manufacturing methods, a sealed hollow container can be obtained by closing the blow holes created when the blow nozzle pierces the parison. The blow nozzle for forming the blow hole preferably has a diameter larger than the relation with the release time of the pressure fluid inside the hollow container. In other words, the larger the diameter of the blowing nozzle, the faster the pressure fluid can be blown into and discharged, and the cooling time can be shortened.

However, when the diameter of the blow nozzle is large, the diameter of the blow hole also becomes large, and it becomes difficult to seal the blow hole. In particular, it has not been possible to obtain a completely sealed state in which the sealed state is not released due to the pressure between the hollow containers during transportation and storage. In addition, in order to reduce the diameter of the blow hole generated by the blow nozzle, it is possible to make the wall thickness of the cylindrical body that constitutes the blow nozzle thin, but the strength of the blow nozzle itself is inferior and it is not stable for a long time. It was difficult to use it. In addition, when the blow nozzle does not penetrate the parison well, there is also the problem that when the parison is pierced, small pieces of resin separate from the area around the blow hole and are scattered as foreign matter into the hollow container in which the molding is performed. . In particular, when blow molding a multilayered parison, delamination occurs between the laminated resins around the blow hole, and this delamination extends to the hollow container being blow molded, resulting in defective products.

[Means to solve the problem]

The present invention has been made in view of the above points, and it is possible to manufacture a good airtight hollow container regardless of the size and structure of the blow nozzle or the size of the blow holes generated thereby, and it is also possible to This solves the conventional problems caused by the embedding process. That is, in the present invention, a parison is disposed between the molds of divided formation in which the container cavity and the bag-like cavity communicate with each other through a narrow recess, the mold is closed, and pressure is applied to the parison of the bag-like cavity from a blowing nozzle. By introducing fluid and introducing the pressure fluid into the parison of the container cavity through the narrow recess, a molded product in which the hollow container and the bag-shaped portion communicate with each other at the narrow portion is blow-molded, and then the narrow portion is cut. The present invention also relates to a method of manufacturing a sealed hollow container that closes a communicating portion of the hollow container. In addition, the communication part of the hollow container should be properly heated and closed, and small pieces of resin separated from around the blow hole may be mixed into the hollow container.
To prevent delamination from progressing around the blow hole,
It is preferable that the opening cross-sectional area of the narrow portion is 50% or less of the external cross-sectional area.

[Effect]

In the present invention, a narrow portion is provided between the hollow container and the bag-like portion to communicate them. In the present invention, the blow hole formed by the blow nozzle is not closed, but the narrow portion other than the blow hole is closed. This narrow portion is a communication hole for pressure fluid and is closed after molding.

In the present invention, when small pieces of resin are separated and scattered from around the blow hole of the bag-shaped part, their movement is prevented in the narrow part, and when blow molding a multilayered parison, the blow hole Even if delamination occurs in the periphery, its progress is prevented in the narrow portion.

〔Example〕

Embodiments of the present invention will be described based on the drawings. 1st
The figure shows a hollow container 1 manufactured according to the present invention, and the hollow container 1 has a body 2, a mouth 3 connected above the body 2 and having a smaller diameter than the body, and a mouth 3 connected to the upper end of the mouth. It consists of a head 4 with a rounded tip.

The head 4 is closed at its tip.
The hollow container 1 has a head 4 cut along a cutting line 4 when filling the contents.
The contents are filled through the opening which is separated from a and opened. A screw 3a is formed in the opening 3, and a cap (not shown) is screwed into the opening 3 after the contents are filled.

Next, the manufacturing method of the present invention is shown in FIGS. 2 to 5.

First, a multilayer tubular thermoplastic synthetic resin 14 (hereinafter referred to as parison), whose inner and outer plasticized layers are made of thick-walled polyolefin and whose middle layer is made of an oxygen barrier resin such as saponified ethylene-vinyl acetate copolymer (hereinafter referred to as parison), is separated. It is introduced into the center of the molds 11 and 12. Here, on mutually opposing surfaces of the split molds 11 and 12, a body cavity 16 and a mouth cavity 1 are provided.
7 and a head cavity 19, and a bag-like cavity 18. A narrow recess 20 is provided between the head cavity 19 and the bag cavity 18 for passage of pressure fluid, and the diameter of this narrow recess 20 is at least as large as the parison 14.
It is more than twice the wall thickness of . Pouch cavity 18
is a blowing nozzle 15 into which pressure fluid is pressurized in a direction perpendicular to the mating surface 11a of the split mold 11;
is formed so that it can slide freely in and out (see Figure 2).

Next, the split molds 11 and 12 are closed, the blow nozzle 15 is inserted into the parison 14, and the pressure fluid is ejected into the parison 14. Blow nozzle 15
is pushed toward the parison 14 from the bag-like cavity 18, and as a result, the blow hole 7 is formed in the bag-like portion 5. After forming the pouch 5, pressure fluid is introduced into the lower part of the parison 14 through the narrow recess 20, and the hollow container 1 and the pouch 5 form the narrow recess 6.
The connected molded product is blow molded (see Figure 3).

The narrow part 6 of the molded product is formed by the narrow recess 20 of the split molds 11 and 12.
The inside is formed so that the hollow container 1 and the bag-shaped portion 5 communicate with each other (see FIG. 4).

Then, the heated heating blade 23 passes the tip of the head 4 and the proximal end 6a of the narrow portion 6 in a direction substantially perpendicular to the axial direction of the hollow container molded product, thereby separating and fusing the bag-shaped portion 5. At the same time, the communicating portion at the upper end of the head 4 is closed to obtain the sealed hollow container 1 shown in FIG. 1 (see FIG. 5).

The heating blade 23 uses a metal plate heated by an electric heater or other heating means, and in the case of a resin whose melting point is relatively close to the temperature at which the resin deteriorates, a temperature control device is added to the heating device. Use a hot plate. The temperature of the heating blade used here depends on the resin, but if it is low-density polyethylene, it will be 120℃.
~350°C is preferred. If it is below 120°C, the resin will not start melting, and if it is above 350°C, the molten resin will easily carbonize. Generally, the temperature of the heating blade 23 is set from a temperature near the melting point of the resin used to a temperature at which the resin begins to carbonize.

Furthermore, in the embodiment, the proximal end portion 6a between the tip of the head and the narrow portion 6 was cut using the heating blade 23 and the communicating portion was closed by melting, but the portion to be cut is not limited in any way as long as the narrow portion 6 It's not something you can do. Furthermore, the means of closing is not limited to the above embodiments, and may be performed by cutting with a cutting blade and then heat welding other members, or by heating with a gas burner, infrared rays, or hot air, and then melting with an extruded member. Various means of sealing the hollow container can be used, such as moving and closing the surrounding resin.

[Effects of the Invention] As described above, since the present invention closes the hollow container at a portion other than the blow hole, there are no limitations on the size and structure of the blow nozzle or the size of the blow hole generated thereby. A good closed hollow container can be manufactured without any interference. Furthermore, by making the diameter of the blow hole relatively large, a large amount of pressure fluid can be ejected and discharged in a short time, and the strength of the blow nozzle is also increased, so that the disadvantage that the blow nozzle breaks during molding can be eliminated. Furthermore, although the present invention can be carried out whether the parison of the present invention has a single-layer structure or a multi-layer structure, it is particularly effective when the parison has a multi-layer structure. That is, when a parison with a multilayer structure is penetrated with a blow nozzle, delamination may occur between the laminated resins, resulting in a molding defect called "delamination." When a blowing nozzle was inserted directly into a hollow container, the delamination reached the mouth of the container, making it unusable as a product. However, according to the present invention, delamination occurring in the bag-shaped part is removed from the narrow part. It is focused at this point, and its progress is blocked at this point, preventing it from reaching the hollow container.

In addition, small pieces of resin scattered when the parison is pierced are prevented from adhering to the bag-like part or being prevented from moving in the narrow part, preventing foreign matter from entering the hollow container. .

[Brief explanation of drawings]

FIG. 1 is a partially cutaway side view of a hollow container obtained by the manufacturing method of the present invention, and FIGS. 2 to 5 illustrate the manufacturing method of the present invention. 3 is a partially enlarged side sectional view showing the state of blowing, FIG. 4 is a partially cutaway side view of the upper part of the hollow container molded body, and FIG. 5 is a side view of the hollow container molded body when sealed. It is a partially cutaway side view of the upper part. 1... Hollow container, 2... Body, 3... Mouth, 4
...Head, 5...Pacific portion, 6...Narrow portion, 7...
Blow hole, 20...Narrow recess, 22...Heating blade.

Claims (1)

[Scope of Claims] 1. A parison is placed between a split mold with a narrow recess communicating between the container cavity and the bag-like cavity, the mold is closed, and a blow nozzle is used to blow the inside of the bag-like cavity into the parison. By introducing pressurized fluid into the parison of the container cavity through the narrow recess, a molded product in which the hollow container and the bag-shaped portion communicate with each other at the narrow portion is blow-molded, and then the narrow portion is closed. A method for manufacturing a sealed hollow container, which comprises cutting the hollow container and closing a communicating portion of the hollow container. 2 The internal opening cross-sectional area of the narrow part is 50% of the external cross-sectional area
A method for producing a closed hollow container according to claim 1, characterized in that the following molded product is blow molded. 3. Claim 1, characterized in that the parison is multilayered, mainly consisting of polyolefin layers.
A method for producing a sealed hollow container as described in Section 1. 4. The method of manufacturing a sealed hollow container according to claim 1, characterized in that the bag-shaped portion is removed by contacting a heated fusing blade to the narrow portion and at the same time, the communicating portion of the hollow container is closed.