Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Reexamination Certificate
2000-05-24
2002-03-12
Short, Patricia A. (Department: 1712)
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
C428S036920, C525S166000, C525S173000, C525S176000
Reexamination Certificate
active
06355319
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application is the National Phase entry, under 35 USC §371, of international application PCT/JP99/04937, filed Sep. 10, 1999, and designating the United States.
TECHNICAL FIELD
The present invention relates to a polyester resin composition and a blow molded container therefrom. More particularly, the present invention relates to a polyester resin composition from which a transparent heat-resistant blow molded container suitable for use to pack potables and other liquids can be molded with high productivity, and relates to a preform formed from the polyester resin composition and a blow molded container obtained by drawing the preform.
BACKGROUND ART
In recent years, various plastic materials are used as a raw material of containers for packing carbonated beverage, juice, natural water, alcohol, various drinking teas, edible oil, liquid flavoring and other liquids. Among them, polyesters such as polyethylene terephthalate (PET) are very often utilized as a raw material of blow molded containers for potables because of the excellence in transparency at molding, gas barrier properties, heat resistance and mechanical strength.
These blow molded containers are often packed with potable having undergone heating sterilization and being still in the hot state. The blow molded containers must have satisfactory heat resistance in order to be free from problems such that the blow molded containers are clouded or caused to suffer from deformation such as shrinking or swelling by hot charged material and such that the self-supporting properties of the blow molded containers are deteriorated by the deformation.
Further, it is strongly demanded that the plastics employed to form the blow molded containers for potables be concurrently transparent.
Still further, in the production of blow molded containers, materials suitable for high-productivity production are demanded, and high-speed production thereof is desired. For realizing high-speed production of blow molded containers, it is desirable to employ a material whose heating crystallization rate is high with a range ensuring smooth molding operation. Thus, a polyester resin exhibiting a high crystallization rate is demanded.
However, when the crystallization rate is extremely high, the width of suitable molding conditions is restricted with the result that the yield at molding production is lowered. Accordingly, it is desirable that the material for producing the above blow molded containers have an appropriate crystallization rate, taking both the molding efficiency and the molding conditions into account. In order to meet this requirement, the polyester is loaded with various compounding agents so that the properties of the molding thereof are regulated.
For example, a polyester resin composition comprising polyethylene terephthalate in which a polyolefin such as polypropylene was contained in an amount of 0.002 to 200 ppm was proposed in Japanese Patent Laid-open Publication No. 8(1996)-302168.
In addition, a polyester resin composition comprising a polyester resin loaded with polypropylene in a content of 0.1 ppb to 1000 ppm was proposed in Japanese Patent Laid-Open Publication No. 9(1997)-194697.
Further, a polyester resin composition comprising a polyester resin composed mainly of ethylene terephthalate units in which polyethylene was contained in an amount of 0.1 to 45 ppb was proposed in Japanese Patent Laid-open Publication No. 9(1997)-151308.
Both the above compositions exhibit accelerated crystallization and maintain transparency still fit for use as compared with those not loaded with compounding agents. However, there is the problem that the transparency thereof is inferior to that of the molding of polyethylene terephthalate only.
When it is intended to increase the crystallization rate without any substantial lowering of transparency, it has been requisite to control the amount of added compounding agent within a range of extremely minute quantity.
The object of the present invention is to provide a polyester resin composition from which, in the molding of blow molded containers, highly heat-resistant transparent blow molded containers can be obtained with high productivity and thus to provide blow molded containers formed therefrom. In particular, the object of the present invention is to provide a polyester resin composition from which blow molded containers of excellent transparency can be obtained and thus to provide blow molded containers formed therefrom.
DISCLOSURE OF THE INVENTION
The polyester resin composition of the present invention comprises:
(A) a polyethylene terephthalate composed mainly of repeating units derived from a dicarboxylic acid containing terephthalic acid and/or an esterified derivative thereof and a diol containing ethylene glycol and/or an esterified derivative thereof, said polyethylene terephthalate containing diethylene glycol units in a ratio of 0.5 to 2.0% by weight based on the polyethylene terephthalate, and
(B) an ethylene/(meth)acrylic acid copolymer, said ethylene/(meth)acrylic acid copolymer (B) contained in the composition in an amount of 0.1 to 10,000 ppb based on the composition.
The content of a cyclic trimer in the polyethylene terephthalate is preferably not greater than 0.5% by weight based on the polyethylene terephthalate.
In this polyester resin composition, it is preferred that the ethylene/(meth)acrylic acid copolymer (B) have a (meth)acrylic acid content of 0.5 to 8% by weight. This polyester resin composition may further contain (C) polyethylene. In the polyethylene containing composition, it is preferred that the ethylene/(meth)acrylic acid copolymer (B) and the polyethylene (C) be contained in the composition in a total amount of 0.1 to 10,000 ppb based on the composition, and that the (meth)acrylic acid content based on the total weight of ethylene/(meth)acrylic acid copolymer (B) and polyethylene (C) range from 0.5 to 8% by weight.
Preforms can be produced from the polyester resin composition of the present invention. Blow molded containers having excellent heat resistance and transparency can be obtained with high productivity by drawing the preforms. Especially, blow molded containers of striking transparency can be obtained with high efficiency.
BEST MODE FOR CARRYING OUT THE INVENTION
The polyester resin composition of the present invention and the blow molded containers formed therefrom will be described in detail below.
<Polyester resin composition>
The polyester resin composition of the present invention comprises a polyethylene terephthalate (A) and an ethylene/(meth)acrylic acid copolymer (B). This polyester resin composition may further contain polyethylene (C).
These components will first be described.
Polyethylene terephthalate (A)
The polyethylene terephthalate (A) for use in the present invention is produced from, as main raw materials, dicarboxylic acids such as terephthalic acid and esterified derivatives thereof (for example, lower alkyl esters and phenyl esters) and diols such as ethylene glycol and ester derivatives thereof (for example, monocarboxylic acid esterified ethylene oxide).
The ratio of diethylene glycol (DEG) units contained in the above polyethylene terephthalate is generally in the range of 0.5 to 2.0% by weight, preferably 0.8 to 1.6% by weight, based on the polyethylene terephthalate.
When the DEG ratio is 0.5% by weight or higher, the transparency of the column part of a molded bottle is excellent. Further, when the DEG ratio is 2.0% by weight or below, excellent heat resistance and crystallization accelerating effect are realized.
As means for regulating the DEG ratio so as to fall within the above range, there can be mentioned the method in which diethylene glycol is used as a starting material of polymerization and the method in which, since diethylene glycol is formed as a by-product from ethylene glycol as a main starting material, the amount of by-product is regulated by appropriately selecting reaction conditions and additives.
Examples of additives capable of inhibiting the
Masumoto Mitsuaki
Nakamachi Koji
Niimi Hiroji
Mitsui Chemicals INC
Short Patricia A.
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