Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Reexamination Certificate
1999-03-02
2001-12-11
Pyon, Harold (Department: 1772)
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
C428S035600, C428S036900, C604S403000, C604S415000
Reexamination Certificate
active
06329031
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a novel polyester resin composition which can form a molded product excellent in transparency, gas barrier property, ultraviolet-screening property, impact strength and the like, and to a reduced pressure blood-collecting tube made using said molded product.
BACKGROUND OF THE INVENTION
Polyethylene terephthalate polymers (which may be hereinafter referred to as “PET”) having ethylene terephthalate units as major structural units have been heretofore widely used for forming molded products such as packaging materials, containers and the like because of their superior properties such as high mechanical strength, transparency, gas barrier property, and hygienic qualities.
However, such PET packaging materials and containers are not always sufficient in gas barrier property against oxygen or other gases, and are unsatisfactory for the drawback of changing the properties of contents in the case of long-term storage, small-size containers or requirement for high gas barrier property. Packaging materials and containers should be essentially transparent to permit inspection of contents and, in such case, should protect the contents against the degradation and the discoloration thereof which occur due to ultraviolet ray irradiation.
For improvements in the gas barrier property of PET packaging materials and containers, it has been proposed to laminate an ethylene-vinyl alcohol copolymer, polyamide resin or other resins which are superior to PET in gas barrier property. However, when a multi-layer structure on PET is stretched, interlaminar separation may occur for a low adhesion of the resins to PET, presumably leading to impairment of gas barrier property. Further because of their low compatibility with PET, these resins of the defective multi-layer molded product can not be reused by mixing with a virgin material to produce a transparent molded product.
A mixture of PET and polyethylene isophthalate or a copolymer thereof was proposed (Japanese Unexamined Patent Publications Nos. 64,624/1984; 64,658/1984; and 315,457/1989). However, a molded product made of the proposed mixture is low in gas barrier property and heat resistance.
A glass tube with a bottom end has been used as a container of high gas barrier property, especially as a reduced pressure blood-collecting tube because it is capable of retaining the reduced pressure for a prolonged time. Yet, since such glass tube is readily damaged and is difficult to handle for its weight, it is currently being replaced by a plastic tube. Nevertheless the plastic reduced pressure blood-collecting tube poses the following problem. The plastic tube has a low gas barrier property compared with the glass tube so that the level of reduced pressure in the tube is decreased with time, and the amount of collected blood is diminished accordingly. For this reason, when a reduced pressure blood-collecting tube is produced, it is necessary to use a resin composition capable of forming a molded product of high gas barrier property.
PET, polyethylene, polypropylene or the like is used as a plastic constituting a reduced pressure blood-collecting bottom-ended tube. Among them, polyethylene is low in transparency and gas barrier property, and is not satisfactory as a plastic constituting a reduced pressure blood-collecting tube. Polypropylene is superior in transparency but inferior in gas barrier property like polyethylene, and is unsatisfactory as a plastic constituting a reduced pressure blood-collecting bottom-ended tube. PET is outstanding in moldability and transparency but low in gas barrier property. Various improvements have been made in the plastics constituting a reduced pressure blood-collecting bottom-ended tube.
For example, Japanese Unexamined Patent Publication No.45,040/1990 proposed a reduced pressure blood-collecting bottom-ended tube made from a mixture of PET and a copolymer of polyethylene isophthalate. However, the proposed tube is defective in the following. 1,3-bis(2-hydroxyethoxy)benzene used as one of the monomers for the copolymer is expensive and is responsible for a high cost of the obtained copolymer. Furthermore, because the copolymer has low impact resistance, the resulting tube is inferior in impact strength, especially drop impact strength. Japanese Unexamined Patent Publication No.22,294/1995 proposed a vacuum blood-collecting tube formed from a mixture of PET with polyester of isophthalic acid, terephthalic acid, 1,3-bis(2-hydroxyethoxy)benzene and ethylene glycol. The proposed tube, however, calls for use of expensive material and is poor in drop impact strength as is the case with the proposal of Japanese Unexamined Patent Publication No.45,040/1990. Hence it is unsatisfactory.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a polyester resin composition which is free of the foregoing drawbacks or problems of conventional techniques, the composition being useful in producing a molded product excellent in transparency, gas barrier property, ultraviolet-screening property, and impact strength.
Another object of the invention is to provide a reduced pressure blood-collecting bottom-ended tube which shows substantially no change in the amount of collected blood with time for a high gas barrier property, the tube being excellent in ultraviolet-screening property, transparency and impact strength, especially drop impact strength.
Other objects and features of the present invention will become more apparent from the following description.
According to the present invention, there is provided a polyester resin composition comprising:
(A) 10 to 90% by weight of a polyethylene terephthalate polymer having 100 to 75 mole % of ethylene terephthalate units; and
(B) 90 to 10% by weight of a polyester resin, the polyester resin being prepared by polycondensation of dicarboxylic acid component and glycol component, the dicarboxylic acid component comprising, based on the total amount of the dicarboxylic acid component, 50 to 92 mole % of isophthalic acid or its ester-forming derivative, 5 to 47 mole % of terephthalic acid or its ester-forming derivative and 3 to 45 mole % of 2,6-naphthalenedicarboxylic acid or its ester-forming derivative, and the glycol component comprising, based on the total amount of the glycol component, 75 to 96.5 mole % of ethylene glycol and 3.5 to 25 mole % of diethylene glycol,
the polyester resin composition having an oxygen permeability coefficient of 3.0 or less cc·mm/m
2
·day·atm.
The present invention is also directed to a molded product formed from said polyester resin composition, and to a reduced pressure blood-collecting tube having a bottom at one end thereof and a plug for closing the opening at the other end thereof, said tube being molded from said polyester resin composition.
The present inventors conducted extensive research to achieve the foregoing objects and found that when said specific polyester resin composition is used, a molded product is produced which is excellent in gas barrier property, impact strength, especially drop impact strength, transparency, and ultraviolet-screening property, and that the reduced pressure blood-collecting tube made using the molded product of the polyester resin composition shows little variations with time in the amount of collected blood and is superior in ultraviolet-screening property, drop impact strength, transparency and the like. The present invention was completed based on these novel findings.
DETAILED DESCRIPTION
The polyester resin composition of the present invention comprises the polyethylene terephthalate polymer (A) and the polyester resin (B).
The polyethylene terephthalate polymer (A) in the polyester resin composition of the invention is a thermoplastic polyester resin containing 100 to 75 mole %, preferably 100 to 80 mole %, more preferably 100 to 85 mole %, of ethylene terephthalate units.
When the polyethylene terephthalate polymer (A) contains other units than the ethylene terephthalate units, dicarboxylic acid component as polycondensation componen
Eto Yoshitaka
Harada Mitsuhiro
Kitagawa Hironobu
Sonoda Hirotoshi
Kenyon & Kenyon
Nolan Sandra M.
Pyon Harold
Toyo Boseki Kabushiki Kaisha
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