JPS602330A - Method of molding bottle of saturated polyester resin - Google Patents

Abstract

PURPOSE:To obtain a bottle that can withstand the internal pressure after it has been filled with the contents and also withstand heating when sterilization is carried out, by cooling a polyester resin bottle from the inside, which bottle is molded by biaxial stretch blow molding, while heating only the bottom part of the bottle so as to crystallize the bottom part. CONSTITUTION:A biaxially stretched polyester resin bottle 1 is clamped by a jig 2, and heating means 4 such as an electric heater, far infrared heater, hot air heating, etc. is arranged below the bottom part 3 of the bottle 1. To cool the inside of the bottle 1, cooling water, cooling air or a refrigerant such as liquefied nitrogen, dry ice is used. The jig 2 is positioned just above the bottom part 3 so that only the bottom part 3 is heated by the heating means 4 and the jig 2 would also serve as a heat conduction shield to prevent the heat from going to the barrel part 5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for molding a saturated polyester resin bottle suitable for filling beverages that are subject to internal pressure and require heat sterilization, such as carbonated beverages containing fruit juice. .

When a normal saturated polyester resin bottle is filled with a content such as a fruit juice-containing carbonated drink, the content becomes 2.5v0.
Due to the presence of fruit juice in carbonated water with a carbon dioxide gas concentration of about 1, after filling the contents and capping it, it will last about 7 hours.
When so-called heat sterilization is performed by immersing the bottle in hot water at 0° C. for about 30 minutes, an internal pressure of 55 to 6.0 kgArir is generated and the bottom of the bottle is deformed by the heating. Therefore, as a method to eliminate the above-mentioned drawbacks, it has been considered to crystallize the bottom of the fuselage. Methods for crystallizing the bottom of this field include a method of crystallizing the middle layer of the parison gate part during injection molding, or a method of crystallizing it by heating with a heater etc. after molding the parison, and then biaxially stretching and blowing the bottom part. There is a crystallized bottle forming method.

The present invention involves gripping a polyester resin bottle molded by biaxial stretch blow molding in a jig, cooling the polyester resin bottle from the inside, and heating only the bottom of the bottle with a heating means to crystallize the bottle. Accordingly, the present invention provides a molding method for filling a polyester resin in which the bottom of the box can withstand internal pressure after filling with contents and heat during heat sterilization without deformation.

Hereinafter, the method for molding the polyester resin according to the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, the present invention includes a biaxially stretched polyester resin body 1 held by a jig 2, and an electric heater placed below the bottom 3 of the body 1.

A heating means 4 such as a far infrared heater or hot air heating is arranged. Furthermore, the inside of the four bodies 1 is cooled by cooling means such as injecting cooling water, feeding cooling air, or using a refrigerant such as liquid nitrogen or dry ice.

The jig 2 is arranged at a position where only the upper part of the bottom part 3, that is, only the bottom part 3 is to be heated by the heating means 4, and also has a heat conduction shielding effect so that the body part 5 is not affected by heat. Also, the mounting position of jig 2 must be changed.
The area to be further crystallized can be changed arbitrarily.

As shown in FIG. 2, the bottom portion 3 is approximately 3.
It has a wall thickness of 0% or more, and has an inner thickness of about 1/9 or more compared to the wall thickness of the piece before biaxial stretch blow molding, and the part of the bottom 3 to be crystallized is , more than 20% of the surface area from its center, and 1 of its bottom inner thickness
0% or more, and the crystallization density is 1.39 VcJ or more.

As described above, by crystallizing the surface layer of the bottom wall thickness (10% or more of the bottom wall thickness), the impact strength against impact such as dropping can be increased.

Next, a specific example of the present invention will be described regarding a bottle with a capacity of 1000 cc for a carbonated beverage containing fruit juice.

Example 1: When an empty bottle is heated 5 cm above a 600W electric heater, no crystallization occurs for 20 seconds.Capacity: 30cc.Shrinkage: NG6
0 sec crystallization Capacity 250 cc Shrinkage NG Example 2 When a bottle is filled with cooling water and heated on a 600W electric heater at 5 cm, no crystallization occurs for 1 minute.No change in capacity.NG 3 minutes Slight crystallization △ 7 minutes Crystallization 0K Burnt for 15 minutes NG Example 3 Pour cooling water into a bottle, cover everything except the bottom with a jig, and boil for 600 minutes.
When heated 5 cm above the electric heater of W, there is slight crystallization for 1 minute, no change in capacity. 2. Four normal bodies without any treatment and four bodies of the same shape with bottom crystallization. l The results of measuring the changes in both bottles when they were filled with VOI carbonated water, capped, and immersed in 70°C warm water for 30 minutes showed that, assuming the normal amount of change for the four bottles to be 100%, the total height increased by 75%. , Incoming line decline 98%.

Lower elongation 60% The result was obtained.

The present invention has the above-mentioned structure, and by cooling the polyester resin charge molded by biaxial stretch blow molding from the inside and heating only the bottom part of the bottle with a heating means to crystallize it, carbon dioxide gas containing fruit juice is produced. It has pressure resistance that can withstand the internal pressure even when filled with beverages containing it, and heat resistance that can withstand heating during heat sterilization. This is a particularly effective molding method for loading polyester resin in which almost no deformation of the body occurs.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the molding method for polyester resin tearing according to the present invention, and Figure 2 is a diagram showing the method for molding the polyester resin tear molding according to the present invention.
It is a partial cross-sectional view of the body. 1: 4 bodies, 2: jig, 3: bottom, 4: heating means. Patent Applicant Yoshino Kogyo Co., Ltd. Representative Osamu Kawa Kawahitoichi Tatsuya Yoshito Fuji

Claims (1)

[Claims] Polyester molded by biaxial stretch blow molding/?
A method for forming a saturated polyester resin bottle, which comprises cooling the resin bottle from the inside and heating only the bottom of the bottle using a heating means to crystallize the bottle.