Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1998-09-30
2001-08-28
Short, Patricia A. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S466000
Reexamination Certificate
active
06281299
ABSTRACT:
This invention relates to methods of manufacturing transparent polyester/polycarbonate compositions, in particular, methods of manufacturing transparent polyester/polycarbonate compositions using equipment for the manufacture of polycarbonates or polyesters by the melt polymerization method.
Polycarbonates have superior mechanical properties such as impact resistance, etc., and further, have superior heat resistance and transparency, and are widely used in applications such as various types of mechanical components, optical lenses and discs, automotive components, etc.
Polycarbonates such as these are traditionally manufactured using methods that react phosgene directly with aromatic dihydroxy compounds such as bisphenol A (interfacial methods) or methods based on ester interchange reactions of carbonate diesters with aromatic dihydroxy compounds in the melt phase, and are normally obtained as pellets, chips or powders.
However, it is desirable that polycarbonates having superior physical properties such as described above also offer further improvements in characteristics such as chemical resistance, moldability and impact strength dependent on thickness.
Accordingly, for many years, methods to improve chemical resistance and moldability by adding polyester to polycarbonate have been given trials.
For example, Publication of Unexamined Patent 5-239333 discloses a method that adds polybutylene terephthalate, ABS or polymethyl methacrylate, etc., during the manufacture of polycarbonates. However, in this method, the hue after mixing and kneading and mixing the base resin is improved, but the transparency and mechanical properties are not expressly stated.
In addition, polycarbonates have excellent mechanical strength, chemical resistance and gas barrier characteristics, and are widely used in applications such as bottles and films used for food products, tapes and fibers as well as automotive parts and various types of mechanical components that exploit its thermal resistance which results from crystallization.
The addition of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc., to polycarbonates is also a well-known method intended to improve chemical resistance and gas barrier characteristics of polycarbonates, and has been commercialized.
Nevertheless, when polyester is kneaded and mixed into the polycarbonate using ordinary methods, the transparency—an outstanding feature of polycarbonates—suffers a significant decline. The inventors have proposed Japanese Patent Application No. 7-345685, “Transparent polyester/polycarbonate composition,” as an improvement on this method. Polyester/polycarbonate compositions manufactured according to this method are transparent and maintain their transparency even at temperatures approaching the glass transition point, but there is a significant decline in the notched Izod impact strength compared to ordinary polycarbonates. Further, the cost rises because, during manufacture, the two resins are kneaded and mixed after both have been melted.
This invention is a method of manufacturing transparent polyester/polycarbonates in which, with respect to equipment using melt polymerization in the manufacture of one of a plural number of resins which are kneaded and mixed, directly adds another resin which is kneaded and mixed, specifically, a method of manufacturing transparent polyester/polycarbonates using manufacturing equipment for polycarbonates or polyesters by melt polymerization methods in which polyester or polycarbonate is added to the polymerization vessel, or to the outlet side of the polymerization vessel, of manufacturing equipment for polycarbonates or polyesters.
This invention also provides a manufacturing method for transparent polyester/polycarbonates comprising manufacturing polycarbonates or polyesters by melt polymerization methods in which polyester or polycarbonate resin is added to the polymerization vessel in which the polymerization reaction is substantially complete, or to the outlet side of the polymerization vessel, or to pelletization apparatus of manufacturing equipment for polycarbonates or polyesters.
In addition, the manufacturing method for transparent polyester/polycarbonates comprises adding specific additives together with the added polyester or polycarbonate in which preferably the ester interchange conversion percentage of the transparent polyester/polycarbonate is from about 1% to about 95%, the ratio by weight of the constituents in the polyester/polycarbonate composition is from about 45/55 to about 3/97, the polyester is polyethylene terephthalate, polybutylene terephthalate and/or polynaphthalene terephthalate, and the polycarbonate is a polycarbonate whose primary constituent is bisphenol A.
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patent: 10-87969 (1998-04-01), None
Nagai Takashi
Saito Akihiro
General Electric Company
Short Patricia A.
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