JPH0656139A - Preform and bottle for biaxial oriented blow molding - Google Patents

Abstract

PURPOSE:To obtain a bottle made of polyethylene terephthalate by biaxial oriented blow molding which is inexpensive to manufacture and has thermal resistance by molding a mouth of a preform separately, crystallizing an inner peripheral wall by thermal treatment and integrating the lower end of the mouth and the upper end of a body by thermal fusing. CONSTITUTION:Only a cylindrical mouth 10 is fabricated by injection-molding. An inner peripheral wail 11 of the mouth 10 is subjected to thermal treatment to be crystallized. Then the mouth 10 is inserted into a predetermined position of a metal mold for injection molding to be injection-molded. At the same time as this molding, the lower end of the mouth 10 is thermally fused with the upper end of a body 20 to be integrated to provided a blow molding preform 100. The preform 100 is then heated to be blow molded to obtain a polyethylene terephthalate bottle 200. Thus even if contents are put at a high temperature, shrinkage of the mouth due to cooling after the putting is small and a cap may not loosen by external vibration or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a preform used at the time of biaxial stretch blow molding of a bottle made of polyethylene terephthalate, which is filled with fruit juice drink, oolong tea, coffee, etc. at high temperature, and a bottle molded by the preform. It is a thing.

[0002]

2. Description of the Related Art Bottles made of polyethylene terephthalate obtained by biaxial stretch blow molding are used for liquid foods, liquid detergents, liquid toiletries, etc., which are filled at room temperature, and recently, aseptic bottles filled at a high temperature of 85 ° C. or higher. It has also come to be used in large quantities in aseptic-filled liquid foods. However, in the case of high temperature filling, the mouth portion contracts due to cooling after the filling, so that there is a problem that the cap attached to the bottle loosens due to external vibration or shock that occurs during distribution of the product. For this reason, many inventions and devices for improving the heat resistance of the mouth of the bottle and reducing shrinkage due to cooling after filling have been made. These inventions and devices can be broadly classified into a method of crystallizing the inner wall of the bottle by heat treatment to impart heat resistance, and a method of using a heat-resistant constituent material in the innermost layer by using a multilayer structure.

[0003]

However, the method of crystallizing the inner wall of the bottle to impart heat resistance is to heat-treat the molded bottle itself or heat-treat a preform used for biaxial stretch blow molding. Therefore, the manufacturing process is complicated and the manufacturing cost is increased. Further, in the method having a multi-layer structure, the material having heat resistance of the innermost layer is expensive resin, so that the manufacturing cost of the bottle is inevitably high. The present invention provides a method for manufacturing a bottle made of polyethylene terephthalate by biaxial stretch blow molding which has relatively low manufacturing cost, low manufacturing cost, and heat resistance.

[0004]

The first aspect of the present invention relates to a bottomed polyethylene terephthalate preform having a mouth, a body and a bottom, which is used for biaxially stretch blow molding. As shown in FIG. 1, the mouth portion of the preform is separately molded, and the inner peripheral wall portion (11) is crystallized by heat treatment. As shown in FIG. 2 (A), the mouth portion of the mouth portion (10) is A biaxially stretched blow molding preform (100), characterized in that the lower end and the upper end of the body are integrated by heat fusion. The second invention is the preform as described above. FIG. 3 is a bottle (200) shown in FIG. 2 (A), characterized in that it is molded by a biaxial stretching blow molding method.

The above-mentioned method of heat-treating the inner peripheral wall portion of the separately formed mouth portion is performed by contacting with a heating die or heating,
It is heated by hot air, infrared rays or a heater.

The portion to be crystallized by heat treatment is to crystallize the inner peripheral wall portion from one-third to two-thirds of the wall thickness of the mouth portion from the inner wall surface of the mouth portion.

[0007]

In the bottle molded using the biaxially stretch blow molding preform of the present invention, the inner peripheral wall of the mouth is crystallized by heat treatment to impart heat resistance, so that the content is 85 °. Even when filled at a high temperature of C or higher, shrinkage of the mouth portion due to cooling after filling is small, and the cap attached to the bottle at the time of distribution of the product is unlikely to loosen due to external vibration or shock.

[0008]

EXAMPLE FIG. 2A is a sectional view of a biaxially stretch blow-molding preform of the first invention, and FIG.
It is a fragmentary sectional view of the bottle of the 2nd present invention which carried out biaxial stretching blow molding using the preform. Next, embodiments will be described in detail with reference to the drawings.

First, only the cylindrical mouth portion was manufactured by injection molding using polyethylene terephthalate. The mouth is inserted into a temperature control mold of 30 ° C, a rod heater is inserted inside the cylinder of the mouth, and the inner wall surface of the mouth is set to 400
It was heated at ° C for 30 seconds. The inner peripheral wall of the mouth portion was crystallized by this heat treatment, and the crystallized portion was the inner peripheral wall portion from the inner peripheral wall surface of the mouth portion to about ½ of the wall thickness of the mouth portion.

Next, the cylindrical mouth portion having the inner peripheral wall portion crystallized is inserted into a predetermined position of an injection molding die for molding a biaxially stretch blow molding preform, and polyethylene terephthalate is used. Injection molding was performed to mold the body and bottom of the preform. Simultaneously with the molding of the body and the bottom, the lower end of the mouth attached to the mold is heat-fused and integrated with the upper end of the body to form the mouth from the top shown in FIG. 2 (A). A biaxially stretched blow molding preform (100) having a body and a bottom was prepared. Generally, a crystallized resin tends to be less likely to be heat-sealed with a normal non-crystallized resin, but the outer peripheral wall portion of the mouth portion is not crystallized, so that it is inserted into the mold. The heat fusion between the lower end of the formed mouth and the upper end of the melted body was good.

Next, the preform having the inner peripheral wall of the mouth portion crystallized was heated to a stretching temperature of about 100 ° C. and biaxially stretch blow-molded, as shown in FIG. 2 (B). A polyethylene terephthalate bottle (200) was prepared. In the production of the above-mentioned bottle, there was nothing particularly troublesome in the production process.

In order to evaluate the produced polyethylene terephthalate bottle, oolong tea at 90 ° C. was filled on the filling machine line, a cap was attached, the bottle was cooled to room temperature, and then the inner diameter of the mouth shrank. The rate was measured and was 0.3
% Or less, and the sealing property of the cap was good. Further, the bottles of this example filled with oolong tea were boxed upright and inverted up to half, and a transportation test of 200 km was carried out by a mixed flight, but there was no bottle with a loose cap and leaked contents.

[0013]

The bottle molded using the biaxially stretched blow molding preform of the present invention has heat resistance because the inner peripheral wall of the mouth is crystallized by heat treatment, and the contents are filled at a high temperature. However, the shrinkage of the mouth portion due to cooling after filling is small, and the inserted cap does not loosen due to external vibration or shock during the distribution of the product. Also, since only the mouth part is heat-treated, the manufacturing process is not relatively complicated,
The manufacturing cost is also low.

[Brief description of drawings]

FIG. 1A is a cross-sectional view of a mouth portion before heat treatment,
FIG. 6B is an explanatory diagram showing a state in which the mouth portion is heat-treated and the inner peripheral wall portion of the mouth portion is crystallized.

FIG. 2 (A) is a cross-sectional view of a biaxially stretch blow molded preform of the first present invention, and FIG. 2 (B) is a biaxially stretch blow molded preform using the preform. FIG. 2 is a partial cross-sectional view of the bottle of the present invention of No. 2.

[Explanation of symbols]

 10 ... Port 11 ... Inner wall 12 ... Outer wall 20 ... Body 30 ... Bottom 40 ... Temperature control mold 50 ... Lot heater 100 ... Preform 200 ... Bottle

Claims (2)

[Claims] 1. A bottomed polyethylene terephthalate preform comprising a top portion, a body portion, and a bottom portion for use in biaxial stretch blow molding, wherein the mouth portion of the preform is molded separately. A preform for biaxial stretch blow molding, wherein the inner peripheral wall is crystallized by heat treatment, and the lower end of the mouth and the upper end of the body are integrated by heat fusion. 2. A bottle molded by a biaxial stretch blow molding method using the preform according to claim 1 of the above claims.