JPH0716914A - Polystyrene resin made biaxially oriented blow molded item - Google Patents

Abstract

PURPOSE:To obtain a styrene resin made biaxially oriented blow molded item which is excellent in transparency, heat resistance, and dropping strength. CONSTITUTION:A molded item consists principally of styrene resin having a syndiotactic structure. The molded item is composed of a mouth part 1, a neck part 2, and a barrel part 3. The mouth part 1 and the neck part 2 are molded in nonorientation, and the barrel part 3 is molded in biaxially orientation. A vessel for drinkables which uses the polystyrene resin made biaxially oriented blow molded item is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polystyrene resin biaxially stretch blow-molded article having excellent transparency, heat resistance and drop strength, which is used for beverage containers and the like.

[0002]

2. Description of the Related Art Conventionally, styrene resins have been used for various trays because they have excellent transparency. Generally used styrene-based resins have an stereotactic regularity of an attack structure, are amorphous and have transparency, but have a drawback of lacking impact resistance. Although there is a method of adding a rubber component or the like in order to improve the impact resistance of this styrene resin, there is a drawback that the transparency is lost. Further, the improvement effect by stretching cannot be sufficiently obtained.

A container made of styrene resin is one of the useful ones used for a heat sterilization container. However, those having impact resistance are opaque and have poor visibility, so that their use is limited. Also, when transparency is utilized, it is inferior in impact resistance, so it is often used in small containers,
It has the drawback that it cannot be used as a large container.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a polystyrene resin biaxially stretched blow molded article which is excellent in transparency, heat resistance and drop strength and is suitable for beverages. . Another object of the present invention is to provide a soft drink container represented by a carbonated drink, which is also useful.

[0005]

That is, the present invention is a molded product mainly composed of a styrene resin having a syndiotactic structure, the molded product comprising a mouth, a neck and a body, and the mouth and the neck are It is intended to provide a polystyrene resin biaxially stretched blow molded article, which is a non-stretched, and whose body portion is biaxially stretched and molded, and a beverage container using the same.

The present invention will be described in detail below. As the styrene resin mainly having a syndiotactic structure of the present invention, for example, resins described in JP-A-62-187708 are used. In the present invention, mainly syndiotactic structure means that the steric structure is mainly syndiotactic structure, that is, the main chain formed from carbon-carbon bonds has phenyl groups and substituted phenyl groups which are side chains alternately in opposite directions. It has a positioned three-dimensional structure. The tacticity can be indicated by the abundance ratio of a plurality of continuous structural units, for example, when it is two, it is represented by a dyad. The weight average molecular weight of the styrene resin having the syndiotactic structure is at least 10
It is more than 10,000.

The styrene-based resin having a predominantly syndiotactic structure used in the present invention has a syndiotacticity of 70% or more as a diad, and particularly preferably 8
It is 0% or more of resin. It is also possible to use a mixture of these with 40% by weight or less of a styrene resin having an atactic structure.

The method for producing the biaxially stretched blow molded article of the present invention is usually a method in which the above-mentioned styrene resin is used to mold a bottomed parison by injection molding, and then it is placed in a molding die and biaxially stretched. Obtained by blow molding. The molded body of the present invention,
The mouth and neck of the molded body are unstretched, and the body is biaxially stretched. More specifically,
The unstretched molding of the mouth and neck means that the stretching ratio is less than 1.5 times. The case where the body is biaxially stretch-formed has a draw ratio of 1.5 times or more, particularly preferably 2 to 6 times. The thickness of each part of the blow molded body is 1.
It is 4 to 8.0 mm and the body is 0.2 to 3.0 mm. If the thickness of the body is less than 0.2 mm, the strength is insufficient.
Further, the haze value of the body of the blow-molded product is 5% or less, and particularly preferably 4% or less. If it exceeds 5%, the transparency is deteriorated and it is not practical. The molded product of the present invention comprises a mouth part, a neck part and a body part, and the neck part may include a support ring useful for supporting the molded product at the time of stretch molding of the bottle and during transportation.

[0009]

FUNCTION AND EXAMPLE In the present invention, by mainly using a resin having a syndiotactic structure or a resin composition comprising the same as the styrene resin, the effect of biaxial orientation of the polymer is exhibited by biaxial stretching. ,transparency,
Improves heat resistance and drop strength. Further, since the impact resistance is improved at the same time, it is not necessary to add a rubber component for making the molded body opaque, and the entire molded body can be kept transparent.

Hereinafter, more detailed description will be given with reference to Examples and Comparative Examples. Example 1 The styrene-based syndiotactic polystyrene used had a weight average molecular weight of 200,000 and
As for Citi, 13 C-NMR analysis showed that the syndiotacticity was 90% in terms of diads. Hereafter, PS
-Abbreviated as SY. Injection-molded PS-SY, weight 5
After molding 0 g of a bottomed parison and adjusting the temperature of the parison, biaxial stretch blow molding was performed with a molding die held at 20 ° C., and the mouth, neck and body shown in FIG. 1 were formed. A 1.5 liter molded body was obtained. The properties of the obtained blow-molded product were as follows. Transparency: Water was put into the blow-molded product, and a visual examination of the liquid volume part was performed, and the liquid volume could be easily visually recognized. The haze value of the body of the molded product was 3%. Heat resistance: The blow-molded body was filled with hot water at 90 ° C. and cooled by water, and the decrease in capacity was 0.2%. There was no leakage of contents from the mouth. Drop strength: After filling with hot water of 90 ° C., the water-cooled container was dropped from a height of 1.5 m, but the contents did not leak. Further, the container was not damaged.

Example 2 Using PS-SY used in Example 1, injection molding was carried out,
After molding a bottomed parison having a weight of 48 g and adjusting the temperature of the parison, biaxial stretch blow molding was performed with a molding die held at 20 ° C., from the mouth, neck and body shown in FIG. A 1.5 liter molded body was obtained. The characteristics of the obtained blow container for carbonated beverages were as follows. Transparency: Water was put into the blow-molded product, and a visual examination of the liquid volume part was performed, and the liquid volume could be easily visually recognized. The haze value of the body of the molded product was 3%. Heat resistance: The blow-molded body was filled with hot water at 90 ° C. and cooled by water, and the decrease in capacity was 0.2%. There was no leakage of contents from the mouth. Drop strength: After filling 3.5 volumes of carbonated water, the container was dropped in an upright state from a height of 1.5 m, but no damage occurred. The 3.5 volume means one containing 3.5 liters of carbon dioxide gas per 1 liter of water. Creep resistance: The obtained blow container was filled with 3.5 volumes of carbonated water, and after being stored at 38 ° C. for 1 day, the change in barrel diameter was 1.0%, which was good.

Comparative Example 1 A general-purpose styrene resin mainly having an atactic structure was injection-molded to mold a bottomed parison having a weight of 50 g, the temperature of the parison was adjusted, and then the molding die was kept at 20 ° C. Was biaxially stretch blow molded to obtain a molded body of 1.5 liters including the mouth portion, neck portion and body portion shown in FIG. The characteristics of the obtained blow container were as follows. Transparency: The amount of liquid inside the container was visible. The haze value of the body of the molded product was 3%. Heat resistance: The decrease in capacity after filling with hot water of 90 ° C. and cooling with water was 0.5%. There was no leakage of contents from the mouth. Drop strength: As a result of dropping a container cooled with water filled with hot water of 90 ° C. from a height of 1.5 m, the container was damaged.

Comparative Example 2 An impact-resistant polystyrene resin obtained by adding a rubber component to a styrene resin mainly having an atactic structure was injection-molded to form a bottomed parison having a weight of 50 g, and the temperature of the parison was adjusted. After that, biaxial stretch blow molding was performed with a molding die held at 20 ° C. to obtain a molded body of 1.5 liters including the mouth portion, neck portion, and body portion shown in FIG. The characteristics of the obtained blow container were as follows. Transparency: It was not easy to visually check the liquid volume inside the container. The haze value of the body of the molded product was 15%. Heat resistance: The phenomenon of capacity after filling with hot water of 90 ° C. and water cooling was 0.3%. There was no leakage of contents from the mouth. Drop strength: As a result of dropping a container cooled with water filled with hot water of 90 ° C. from a height of 1.5 m, the container was damaged.

[0014]

As described above, according to the present invention, the container biaxially stretch-blow molded mainly using the styrene resin having the syndiotactic structure is excellent in transparency, heat resistance and drop strength. .

[Brief description of drawings]

FIG. 1 is an outline view of blow-molded articles obtained in Example 1 of the present invention and Comparative Examples 1 and 2.

FIG. 2 is an outline view of a blow-molded product obtained in Example 2 of the present invention.

[Explanation of symbols]

 1 Blow Molded Mouth 2 Blow Molded Neck 3 Blow Molded Body 4 Backside of Blow Molded 5 Blow Molded Partial Sectional View

Claims (2)

[Claims] 1. A molded body mainly composed of a styrene resin having a syndiotactic structure, wherein the molded body has a mouth portion,
It consists of a neck and a body, and the mouth and neck are unstretched,
A biaxially stretch blow molded body made of a polystyrene resin, wherein the body is biaxially stretch molded. 2. A biaxially stretched blow container made of polystyrene resin for beverages, comprising the molded body according to claim 1, wherein the body has a haze value of 5% or less.