JPH1148315A - Manufacture of container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a container having an excellent appearance of the container and a good fitness of the cap. SOLUTION: The container manufacturing method is to manufacture a container 3 such as PET bottle by injection molding a parison 3 of polyethylene terephthalate or an olefinic resin having the mouth part 3a and trunk 3b of the container, and stretching the parison 3 by a blow mold 7 through biaxial biaxial orientation molding, and upon injection molding the parison 3, at least one recessed support ring 6 is circumferentially set on the outer circumference of the mouth part 3a, and upon stretch molding the parison 3, the support ring 6 is supported at the blow mold for orientation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a container made of polyethylene terephthalate or olefin resin.

[0002]

2. Description of the Related Art Conventionally, when a container is made of polyethylene terephthalate (hereinafter referred to as PET) or an olefin resin, a parison having a mouth and a body of the container is injection-molded in advance, and the parison is biaxially stretch-molded. However, the parison needs to be provided with a holding portion (support ring) for holding the container in the blow mold, and as shown in FIG. Has a support ring 11 protrudingly formed.

[0003]

However, in order to suppress the stress applied to the parison at the time of stretching at one point of the support ring, the support ring must be enlarged to some extent, and as a result, the diameter of the support ring 11 is located at the upper part thereof. It was necessary to make the size equal to or larger than the screw portion 10a. Therefore, as shown in FIG. 8B, when the cap 12 is screwed, the cap 12 must be formed so that the lower end of the cap 12 does not abut on the support ring 11, so that the compatibility of the cap is inferior. I had to be restricted. In addition, support ring 1
The appearance is not good due to 1 being large,
Material costs in mass production could not be neglected.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a method for producing a container which improves the external appearance of the container and has excellent compatibility with the cap.

[0005]

In order to solve the above-mentioned problems, a method of manufacturing a container according to the present invention comprises injection-molding polyethylene terephthalate or an olefin-based resin into a parison having a mouth portion and a body portion of a container. In a method for manufacturing a container such as a PET bottle by extending the parison by biaxial stretching molding with a blow mold, at least one concave groove-shaped support ring is formed around the outer peripheral surface of the mouth when the parison is injection-molded. When the parison is biaxially stretch-formed, the support ring is stretched while being supported by a blow mold.

[0006]

1 to 4 show a method of manufacturing a container. First, a cavity mold 1 is made of PET as a material.
The parison 3 is injection-molded with the core mold 2. The mouth 3a and the body 3b of the container are formed in the parison 3, and the mouth 3a is formed in a predetermined size, but the body 3b is in a contracted state.

At the time of injection molding in the cavity mold 1, a screw 5 for screwing the cap of the container by the neck mold 4 is formed at the mouth 3a of the parison 3, and a gap is formed between the screw 5 and the body 3b. An annular groove-shaped support ring 6 is formed on the outer peripheral surface of the ring (see FIG. 2).

[0008] The parison 3 formed by injection molding is transferred to a blow mold 7 together with a neck mold 4 as shown in FIG. Then, the body 3b is extended in the axial direction of the extension rod 8 and in the width direction of the body 3b by blowing air from the extension rod 8 as shown in FIG.

In this way, the parison 3 is stretched in the axial direction of the stretching rod 8 by the air blown from the stretching rod 8 and the parison 3 is stretched in the direction perpendicular to the axial center, as shown in FIG. Then, a container 9 (see FIG. 5) having a groove-shaped support ring 6 in the mouth 9a is formed. Since only the mouth 3a is fixed to the neck mold 4 during the stretch molding, stress is applied to the mouth 3a, particularly the support ring 6 during stretching, but since the support ring 6 is formed in a concave groove shape, The screw can be held against a larger stress than a convex support ring formed so as to protrude around the conventional mouth 3a.

This is apparent from the result of measuring the deflection by applying a load to the support ring of the container formed by biaxial stretching. In this measurement, in the case of a conventional convex support ring container having a thickness of 4.8 mm and a width of 4.1 mm, a deflection of 0.4 mm was measured when a load of 10 kg was applied, but a depth of 0 mm was measured. For a container with a support ring in the form of a groove having a width of 3.2 mm and a width of 3.2 mm, a deflection of only 0.1 mm was measured when a load of 10 kg was applied. This also indicates that the groove-shaped support ring can withstand higher stress.

According to the container manufacturing method described above, since the support ring 6 is formed in a concave groove shape when the parison 3 is formed, the screw is held against a large stress at the time of stretching during biaxial stretching molding. As a result, the stretching ratio can be increased, and the wall pressure of the container can be reduced. In addition, there is no extra protrusion between the screw 5 and the body 9b, the appearance is clear and the design is excellent, and the obstruction when screwing the cap 12 is eliminated, so that the compatibility with the cap is improved (see FIG. 6). .

Further, as shown in FIG. 7, a support ring 6 may be formed at the front end and the rear end of the screw 5 at the mouth 3a 'of the parison 3'. Support ring 6 in two places
By forming, during biaxial stretching molding, a holding force approximately twice as large as that of one support ring can be generated, and molding with a higher stretching ratio can be performed.

By increasing the stretching ratio, the thickness of the container can be reduced, the container can be made of a small amount of material, and it is suitable for environmental problems, and various physical properties such as clearness through which the inside of the container can be seen can be improved. .

[0014]

According to the container manufacturing method of the present invention, by providing a concave groove-shaped support ring around the mouth of the parison, a large holding force against stress during stretching by biaxial stretching is provided. As compared with the conventional support ring, the resistance to stress during stretching is remarkably improved, so that the stretching ratio can be increased and a thinner container can be formed.

[0015] In addition to the fact that the container can be made thinner, the support ring is formed in a concave groove shape, so that no extra material is required as compared with the convex support ring, thereby reducing the manufacturing cost and saving resources. be able to.

In addition, since unnecessary projections are eliminated, the external appearance is improved, and there is no obstacle to screwing the cap, so that the compatibility of the cap can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory view of injection molding a parison.

FIG. 2 is a front view of a parison.

FIG. 3 is a cross-sectional view showing a state in which the parison is transferred to a blow mold.

FIG. 4 is a sectional view showing a state where air is blown.

FIG. 5 is a front view of the container.

FIG. 6 is a front view of the container with the cap cut, showing the relationship between the container and the cap.

FIG. 7 is a front view showing another example of the parison.

8 (a) and 8 (b) are front views showing a state in which a conventional support ring and a cap are screwed.

[Explanation of symbols]

 3 parison 3a mouth 3b fuselage 6 support ring 9 container

Claims (1)

[Claims] An injection molding of polyethylene terephthalate or an olefin resin into a parison having a mouth portion and a body portion of a container, and the parison is extended by a biaxial stretching molding with a blow mold to form a container such as a PET bottle. In the manufacturing method, at least one concave groove-shaped support ring is provided around the outer peripheral surface of the mouth when the parison is injection-molded, and the support ring is supported by a blow mold when the parison is biaxially stretch-molded. And producing the container.