Polyester resin, molded articles thereof, and process for production of the articles

Abstract

The present invention relates to a polyester resin, which is an aromatic polyester characterized in that the molecular weight distribution has a dispersion ratio Mw / Mn of 3.00 or more and mainly has a repeating unit composed of an aromatic dicarboxylic acid component and a glycol component , the flow characteristics of this resin are improved, so the amount of aldehydes generated during molding is small, and when it is formed into a molded body, it provides a molded body with excellent mechanical properties such as pressure resistance. In addition, this resin can be molded efficiently at high speed molding It can be used as a molded article with small deformation and excellent heat-resistant dimensional stability, especially a hollow molded article, and a polyester stretched hollow molded article with less pollution to the mold, excellent long-term continuous moldability, and excellent fragrance retention.

Description

technical field [0001] The present invention relates to a polyester resin suitable for use as a raw material for moldings such as hollow moldings represented by beverage bottles, sheets, stretched films, etc., and polyester moldings formed therefrom, particularly acetaldehyde etc. Formation of aldehydes is suppressed, excellent in transparency with little change in transparency, and a hollow molded product with excellent pressure resistance or pressure resistance and heat resistance dimensional stability, excellent in transparency, sliding and dimensional stability after molding Polyester moldings such as sheets and stretch films and methods for producing polyester moldings. Background technique [0002] Polyester whose main repeating unit is ethylene terephthalate (hereinafter sometimes referred to as PET), because of its excellent transparency, mechanical strength, heat resistance, gas barrier properties, etc., is used as carbonated beverages, fruit juices, It is widely u...

AI Technical Summary

Problems solved by technology

However, even with the use of polyester molded articles obtained by these methods, oligomers and acetaldehyde cannot be reduced to a non-problematic level, and the problem has not been solved and has yet to be solved.

[0010] In addition, in recent years, the thickness of the bottle has been reduced, and in order to increase the strength of the bottle along with this, attempts have been made to increase the molecular weight. However, due to the increase in the molecular weight, the melt viscosity during molding has increased, and the problem of increased acetaldehyde generation has arisen.

[0011] In addition, a method for producing a heat-resistant polyester container has been proposed in which a preform formed of a melt-mixed composition of two types of PET having different intrinsic viscosities of 0.03 or more is processed in a heat-setting mold under specific temperature conditions (e.g. Referring to Patent Document 1) and the obtained heat-resistant polyester container (Japanese Patent Publication No. 62-58973), it will have an intrinsic viscosity of 0.60 to 0.70 dl / g, a specific crystallization temperature when the temperature is raised, and a specific crystallization temperature when the temperature is lowered. Manufacture of preform stretch blow molded heat-resistant polyester containers made of polyester and a mixture of polyester with an intrinsic viscosity of 0.77-0.90dl / g and a specific crystallization temperature when the temperature is raised and a specific crystallization temperature when the temperature is lowered methods (for example, refer to Patent Document 2), but even with these methods, there are still problems in obtaining molded articles with stable transparency and reduced acetaldehyde content.

[0012] In addition, a compound of solid-phase polymerized PET and co-polyethylene terephthalate has been proposed (see Patent Document 3). Although the acetaldehyde content of the hollow molded product can be reduced by using it, the obtained There are problems in the heat resistance and pressure resistance of the molded body, which cannot meet the requirements and need to be solved

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