JPH09124024A - Polyester bottle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide excellent heat resistance, pressure resistance and shock resistance for the bottom part of a bottle by a method wherein a circular face for contacting the ground is provided at the bottom while an indent approximately in a spherical shape being provided at the inside of the circular face with its thickness being a specified times the thickness of the trunk part of the bottle, and whitening is made to the indent by heat crystallization. SOLUTION: A preform 3 with a thick part 32 formed at the inside of its bottom 31 is heated in a metal mold for forming bottle main body to a molding temperature generally at 95-115 deg.C, and a fluid is blown into the preform 3 and a bottle main body is formed by blow molding, and thereby a polyester bottle with its bottom 1 formed in a circular face 11 for contacting the ground is formed with an indent 12 approximately in a spherical shape provided at the inside of the circular face with the thickness thereof being five times or more the thickness of the trunk part 2 of the bottle. The indent 12 is heat treated with the bottom of a metal mold for blow molding heated to a temperature at 130 deg.C or more and whitened by heat crystallization. Thereby, a bottle suitable for carbonated beverage requiring heat treatment is obtained with its bottom 31 being highly heat resistant, pressure resistant and shock resistant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blow-molded polyester bottle having excellent heat resistance and pressure resistance at the bottom.

[0002]

2. Description of the Related Art Polyester bottles represented by polyethylene terephthalate are required to have heat resistance and pressure resistance in applications requiring heat sterilization under internal pressure, such as when used for carbonated beverages containing fruit juice. In the polyester bottle of, especially, the bottom part that is easily stretched and deformed easily has a pressure resistant shape protruding in a hemispherical shape, and a hakama-shaped base cup is attached to the bottom part,
It has been performed to provide self-supporting property by projecting a plurality of legs from a hemispherical bottom.

[0003]

However, in the former case where the base cup is mounted, waste of materials and mounting occurs, the base cup hinders recovery and recycling of the polyester bottle, and the base cup is heat-sterilized. In this case, there is a problem in that the thermal efficiency is lowered, and in the latter case where a plurality of legs are formed by protrusion, there is a problem in that they cannot withstand the high temperature and high pressure at the time of heat sterilization and are deformed.

Therefore, the present invention is excellent in heat resistance and pressure resistance,
Moreover, it is an object to provide a polyester bottle having excellent impact resistance.

[0005]

DISCLOSURE OF THE INVENTION The present invention is to solve the above problems, and its gist is to have a bottom portion having an annular grounding surface and a substantially spherical concave portion inside thereof, and the concave portion It is a polyester bottle having a thickness of 5 times or more of the wall thickness and being heat-crystallized and whitened.

Since the bottom recess is made thicker and heated and crystallized, it has excellent heat resistance and pressure resistance. Since the heat crystallized recess is located inside the annular grounding surface, the annular grounding surface becomes brittle. Without this, a polyester bottle excellent in impact resistance can be obtained.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the accompanying drawings. FIG. 1 is a partially cutaway front view showing an example of the polyester bottle of the present invention, and FIG. 2 is a half sectional view showing an example of a preform.

In the present invention, as shown in FIG. 1, the bottom portion 1 has an annular grounding surface 11 and a concave portion 12 having a substantially spherical shape inside thereof, and the concave portion 12 has a thickness of 5 times or more the thickness of the body portion 2. And a polyester bottle characterized by being heat-crystallized and whitened.

In order to manufacture this polyester bottle, as shown in FIG. 2, a method in which a thick portion 32 is formed on the inner surface of the bottom 31 of the preform 3 and the preform 3 is blow molded is used. is there.

By blowing a fluid into a preform 3 heated to a molding temperature, generally 95 to 115 ° C., into a mold for molding a bottle main body, and performing blow molding to form a bottle main body, as shown in FIG. The bottom portion 1 has an annular grounding surface 11 and a recessed portion 12 having a substantially spherical shape inside thereof, and the recessed portion 12 can provide a polyester bottle having a thickness of 5 times or more the wall thickness of the body portion 2. The bottom mold is heated to 130 ° C. or higher to heat-treat the concave portion 12 to heat-crystallize and whiten it, so that it has excellent heat resistance, pressure resistance, and good impact resistance. A polyester bottle suitable for beverages is obtained.

[0011]

EXAMPLE When the preform 3 as shown in FIG. 2 was blow-molded to form the polyester bottle as shown in FIG.
A polyester bottle having a thickness of 0.3 mm and a concave portion 12 having a thickness of 4 mm was obtained, and the concave portion 12 was heat-treated at 130 ° C. to be crystallized by heating to be whitened.

The obtained polyester bottle was filled with carbonated water in which 2.5 gas volume of carbon dioxide was dissolved, sealed, heat-sterilized for 40 minutes in a hot water shower at 70 ° C., and visually observed. As a result, there was no remarkable deformation, and even if it was dropped from a height of 1 m, it did not break, and it was excellent in heat resistance, pressure resistance, and impact resistance.

In this embodiment, the gas volume is 2
When carbon dioxide gas is dissolved in water at 0 ° C. and 1 atm, it is represented by the ratio of the volume of carbon dioxide gas to be dissolved to the volume of water.

[0014]

According to the present invention, the bottom portion has an annular grounding surface and a substantially spherical concave portion inside thereof, and the concave portion has a thickness of 5 times or more the thickness of the body portion and is heat-crystallized. Since it is a polyester bottle characterized by being whitened,
It has excellent heat resistance and pressure resistance, as well as impact resistance.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing an example of a polyester bottle of the present invention.

FIG. 2 is a half sectional view showing an example of a preform.

[Explanation of symbols]

 1 Bottom 11 Annular Grounding Surface 12 Recess 2 Body

Claims (1)

[Claims] 1. A bottom portion has an annular grounding surface and a substantially spherical concave portion inside thereof. The concave portion has a thickness of 5 times or more the wall thickness of the body and is heat-crystallized and whitened. A polyester bottle characterized by that.