JPH07164436A - Synthetic resin bottle and production thereof - Google Patents

Abstract

PURPOSE:To enhance internal pressure strength by forming a thin-walled shoulder part between the body part and neck part of a preform for a synthetic resin bottle and heating the preform so that the temp. of the body part becomes higher than that of the thin-walled shoulder part to subject the same to biaxial stretching blow molding to increase the thickness of the shoulder part without reducing the thickness of the body part. CONSTITUTION:A preform 4 is constituted of an opening edge part 6, a screw 5, a neck support ring 14, a thin-walled shoulder part 8, a body part 9 and a closed part 10. The preform 5 is fitted to a mandrel 12 to be rotated and the outside of the body part 9 is heated by a heater 13. By this heating, the thin-walled shoulder part 8 is heated to temp. lower than that of the body part. Then, the preform is set to a blow mold to be subjected to biaxial stretching blow molding. By this constitution, the shoulder part 8 is increased in thickness to the min. without reducing the wall thickness of the body part 9 and strength against internal pressure can be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin bottle preform suitable for filling carbonated drinks, soft drinks, etc., a bottle and a bottle manufacturing method using the same. In particular, the present invention provides a synthetic resin bottle preform that exhibits an excellent effect on internal pressure resistance, a bottle using the same, and a method for manufacturing a bottle.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 2, a synthetic resin bottle filled with carbonated drinking water has a body portion 1 having a circular tubular shape and a shoulder portion 2 having a substantially spherical shape. Since the shape is excellent, the body 1 and the shoulder 2 are thin.

[0003]

Recently, as shown in FIG. 3, the synthetic resin bottle is strongly desired by the customer to have a shape in which the shoulder portion 3 is a rounded shoulder. However, when a synthetic resin bottle with shoulders is filled with carbonated drinking water, the shoulder portion 3 is greatly deformed by the internal pressure, the shape desired by the customer cannot be maintained, and the taste line is greatly reduced, making a final purchase. There is a problem that people are at risk of lack of capacity. For this problem, it is conceivable to make the shoulder portion 3 thicker, but if it is formed by ordinary biaxial stretch blow molding, it becomes thicker than necessary, and the body portion becomes thin accordingly, and the deformation of the body portion is large There is a drawback that The present invention solves the above-mentioned drawbacks, and suppresses the thickening of the shoulder portion 3 as much as possible and realizes the shape maintenance against the internal pressure.

[0004]

That is, the first aspect of the present invention is a synthetic resin bottle preform comprising a bottomed hollow body having an open edge at the upper end and a closed portion at the lower end. The synthetic resin preform has a thin shoulder between the body and the neck, and the second invention is the synthetic resin bottle preform. A third aspect of the present invention is a synthetic resin bottle obtained by biaxially stretch-blow molding a reform, wherein the synthetic resin bottle preform is heated to a temperature suitable for stretching, and is set in a mold. In the axial stretch blow molding method, the preform is heated so that the temperature of the body portion of the synthetic resin bottle preform becomes higher than the temperature of the thin shoulder portion, and biaxial stretch blow molding is performed. This is a method for manufacturing a resin bottle.

The present invention will be specifically described below with reference to the drawings. FIG. 1 is a diagram showing a preform 4 and an infrared heater 13 for heating the preform 4 of the present invention. As shown in FIG. 1, the preform 4 has an opening mouth edge portion 6, a cap screwing screw 5, a neck support ring 14, a thin shoulder portion 8, a body portion 9 and a closing portion 10 (round bottom portion) in this order from the upper end. Composed. The preform 4 is fitted into the mandrel 12, rotated while being inverted, and the outside of the body portion 9 of the preform 4 is heated by the infrared heater 13. When the body 9 is heated to a temperature suitable for stretching, the preform 4 is set in a blow molding die and biaxially stretch blow molded. When the preform is heated, the thin shoulder portion 8 which is not heated by the infrared heater 13 is heated by heat transfer from the preform body portion 9, but has a temperature slightly lower than the body portion temperature. Therefore, it is rarely stretched in the blow molding process, and the thickness retention rate of the thin shoulder portion is in the range of 30 to 95%. The temperature of the body of the synthetic resin bottle preform is kept at least 10 ° C. or higher, preferably 15 ° C. or higher than the temperature of the thin shoulder, set in a blow mold and biaxially stretch blow molded.
The thin shoulder portion 8 of the preform of the present invention means that the ratio of the minimum outer diameter value of the thin shoulder portion 8 to the outer diameter value of the neck support ring lower portion 15 is 100% or less, preferably 25 to 95%. . The portion including the opening edge portion 6, the cap screwing screw 5, and the neck support ring 14 is generically called a neck portion.

Resins used for producing the preform of the present invention include saturated polyester resins and copolymers thereof.

The thin shoulder 8 of the preform 4 of the present invention.
The length and thickness are designed according to the shape of the synthetic resin bottle. The thickness of the thin shoulder portion 8 is generally 10 mm or more, and the thickness is usually constant, but a thickness that changes in an inclined manner can be used if necessary. Further, the position of the infrared heater 13 is set to the thin shoulder portion 8
It is desirable to be on the body 9 side with respect to the boundary between the body 9 and the body 9.

The preform of the present invention can be easily obtained by a usual injection molding method.

When the synthetic resin bottle of the present invention is filled with carbonated drinking water, the height of the solid line of the synthetic resin bottle is preferably low, and the lower value means less deformation due to internal pressure. This means that the initial shape of the bottle has been maintained.

[0010]

The present invention will be described in detail below with reference to examples.

Example 1 Polyethylene terephthalate (Intrinsic viscosity 0.84, trade name RT553C manufactured by Nippon Unipet Co., Ltd.) was used by using a biaxial stretch blow molding machine (Model LB-01) manufactured by Krupp Corpoplast (Germany). Using injection molding,
Preform with the shape shown in Fig. 1 (total length of preform 150
mm, weight 55 g, thin shoulder length 50 mm, thickness 1.
5 mm) was obtained. The body of this preform is 105 ℃,
The thin shoulder is heated to 85 ° C, then set in a mold, and compressed air is blown into the preform, and at the same time the inner bottom of the preform is pushed by an air cylinder to perform biaxial stretch blow molding. The synthetic resin bottle of FIG. 3 (total length 305 mm, barrel diameter 98 mm, internal volume 1500 ml) was obtained. The synthetic resin bottle was filled with 4.0 volume of carbonated water and stored in an oven at 38 ° C.
Each day was measured up to 7 days. The test results are shown in FIGS. As shown in FIG. 5, the wall thickness of the bottle shoulder portion was smaller and the wall thickness of the bottle body portion was larger than in Comparative Example 1. Further, as shown in FIG. 6, the height of the flavoring line was low and good.

Comparative Example 1 The same as Example 1 except that the preform (total length 130 mm) shown in FIG. 4 having no thin shoulder portion was used, and this was biaxially stretch blow-molded to obtain a synthetic resin bottle. Went to. The test results are shown in FIGS. The taste line height was high. The measuring method was as follows. 1) Thickness distribution 25 to 255 mm from the tip of the open mouth edge of the synthetic resin bottle
Up to 10 mm intervals were measured with a micrometer. 2) Height of taste line The height from the tip of the open mouth edge of the synthetic resin bottle to the liquid level of the content was measured.

[0013]

As is clear from the above invention, the use of the preform provided with the thin shoulder portion of the present invention, and
The temperature of the body is heated to a temperature higher than the temperature of the thin shoulder, and by biaxial stretch blow molding, the shoulder of the synthetic resin bottle is made thin to the minimum necessary without thinning the body, To obtain a synthetic resin bottle having improved strength against internal pressure and a method for producing the same.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a preform and an infrared heater according to the present invention.

FIG. 2 is a front view of a conventional synthetic resin bottle.

FIG. 3 is a front view of a synthetic resin bottle according to the present invention (Example 1).

FIG. 4 is a cross-sectional view of a preform of Comparative Example 1.

FIG. 5 shows the results of Example 1 and Comparative Example 1 of the present invention.

FIG. 6 shows the results of Example 1 and Comparative Example 1 of the present invention.

[Explanation of symbols]

 1 Bottle Body 2 Bottle Shoulder 3 Nades Shoulder Bottle Shoulder 4 Preform 5 Cap Screw Screw 6 Open Mouth Edge 7 Neck 8 Thin Wall Shoulder 9 Body 10 Closure 12 Mandrel 13 Infrared Heater 14 Neck Support Ring 15 Neck Support ring bottom

Claims (3)

[Claims] 1. A synthetic resin bottle preform having a bottomed hollow body having an open mouth edge portion at an upper end and a closed portion at a lower end, wherein the preform has a body portion and a neck portion. A synthetic resin bottle preform characterized by having a thin shoulder portion. 2. A synthetic resin bottle obtained by subjecting the synthetic resin bottle preform according to claim 1 to biaxial stretch blow molding. 3. A synthetic resin bottle preform according to claim 1, wherein the synthetic resin bottle preform is heated to a temperature suitable for stretching, set in a mold, and biaxially stretch blow molded. A method for producing a synthetic resin bottle, characterized in that the preform is heated so that the temperature of the body part thereof is higher than the temperature of the thin shoulder part, and biaxially stretch blow molded.