JPH0321424A - Hollow molding - Google Patents

Abstract

PURPOSE:To obtain excellent mechanical properties, transparency as well as gas barrier properties by a method wherein polyester resin composition, which contains specific ratio of polyethylene terephthalate resin and specified copolymer polyester resin, is stretched by the specified stretching index. CONSTITUTION:Preform is obtained by mixing 80-95wt.% of polyethylene terephthalate resin and 5-20wt.% of copolymer polyester resin containing dicarboxylic acid constituent unit, which consists of 20-100mol% of isophthalic acid component unit and 0-80mol% of terephthalic acid component unit, dihydroxy compound constituent unit, which consists of 5-90mol% of dihydro- ethoxy-resorcinol component unit and 10-95mol% of ethylene glycol component unit, and 0.05-1.0 pts.mol. of trimethylolpropane constituent unit with respect to 100 pts.mol. of the dicarboxylic acid constituent unit, for forming. A biaxially stretched bottle is obtained from the obtained preform. In addition, the stretching index calculated by the formula in this case is set to be 130 or more.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a hollow molded article having excellent properties such as gas barrier properties, transparency, and mechanical strength.

Technical Background of the Invention So-called PET (polyethylene terephthalate) resin has been known as a polyester resin composition having gas barrier properties.

PET resin generally has excellent mechanical strength and transparency, and also has good moldability such as melt moldability and stretchability, and is also lightweight. Therefore, certain shapes made of PET resin are widely used, for example, as containers for carbonated drinks or sparkling beverages such as beer mugs, or containers for seasonings, detergents, and cosmetics.

By the way, in containers for seasonings, detergents, cosmetics, etc., although mechanical strength and transparency may be a problem, gas barrier properties are rarely a problem.

However, for example, containers for carbonated drinks or sparkling drinks such as beer are filled with high-pressure carbon dioxide gas, so they must have extremely high gas barrier properties to prevent the internally filled gas from leaking. is required. To use polyethylene terephthalate resin in applications that require such strict gas barrier properties, gas barrier properties must be ensured by increasing the wall thickness of the container, which is disadvantageous in terms of cost. be.

Currently, the demand for polyester resin containers is increasing year by year. Therefore, in order to use polyester resin containers in the above applications, it is necessary to impart high gas barrier properties to polyethylene terephthalate resin without impairing the excellent properties of the polyethylene terephthalate resin currently used. .

In response to such demands, polyethylene terephthalate resin compositions have been proposed in which various improvements have been made to polyethylene terephthalate resins.

For example, the patent application filed earlier by the applicant in 1986-20
No. 5,739 proposes a resin composition in which a polyhydroxypolyether resin is blended with a PET resin as a PET resin composition with gas barrier properties that can withstand storage and transportation of carbonated drinks and the like. The container molded from the PET resin bottom described in the above specification has excellent gas barrier properties compared to conventional PET resin containers.

Claims (1)

[Claims] 1) 80 to 95% by weight of polyethylene terephthalate resin
and 5 to 20% by weight of a copolymerized polyester resin, and the copolymerized polyester resin has dicarboxylic acid constituent units consisting of 20 to 100 mol% of isophthalic acid component units and 0 to 80 mol% of terephthalic acid component units. , 5-90
A dihydroxy compound structural unit consisting of mol% of dihydroxyethoxyresorcinol component units and 10 to 95 mol% of ethylene glycol component units, and a polyfunctional hydroxy compound structural unit having at least 3 hydroxy groups per 100 mol parts of dicarboxylic acid structural units. 0.0
5 to 1.0 mole part, and has a stretch index of 130 c as defined below.
A hollow molded body characterized by being highly stretched to more than m. Stretching index = Inner volume of stretched bottle (excluding spout)/Inner volume of unstretched preform (excluding spout) x (1/f)
f=Inner surface area of stretched bottle (excluding the inner surface of the spout)/Inner volume of the stretched bottle (excluding the volume of the spout) (cm^-^1
)2) Consisting of 80 to 95% by weight of polyethylene terephthalate resin and 5 to 20% by weight of copolymerized polyester resin, wherein the copolymerized polyester resin contains 20 to 100 mol% of isophthalic acid component units and 0 to 80 mol% of isophthalic acid component units. a dicarboxylic acid constituent unit consisting of a terephthalic acid constituent unit, and 5 to 90
Contains mol% of 1,3-bis(2-hydroxyethoxy)benzene component units or 1,4-bis(hydroxyethoxy)benzene component units and dihydroxy compound constituent units consisting of 10 to 95 mol% of ethylene glycol component units. A hollow molded article made of a polyester resin composition, characterized in that it has been highly stretched to a stretching index of 130 cm or more as defined below. Stretching index = Inner volume of stretched bottle (excluding spout)/Inner volume of unstretched preform (excluding spout) x (1/f)
f=Inner surface area of stretched bottle (excluding the inner surface of the spout)/Inner volume of the stretched bottle (excluding the volume of the spout) (cm^-^1
)