Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Patent
1989-10-17
1993-04-20
Foelak, Morton
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
521 56, 521 64, 521180, 521918, C08J 928
Patent
active
052043770
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a porous, crystallized, aromatic polycarbonate prepolymer, a porous, crystallized aromatic polycarbonate, and production methods therefor. More particularly, the present invention is concerned with a porous, crystallized, aromatic polycarbonate prepolymer having terminal hydroxyl and aryl carbonate groups in a specific molar ratio and having a specific number average molecular weight, surface area and crystallinity, which can readily be converted by solid-state condensation polymerization to a porous, crystallized aromatic polycarbonate having excellent properties. The porous, crystallized aromatic polycarbonate of the present invention can readily be molded to obtain a shaped, porous, crystallized polycarbonate. The porous, crystallized aromatic polycarbonate and the shaped, porous, crystallized polycarbonate of the present invention have excellent heat resistance and solvent resistance and exhibit advantageously low water absorption so that they are suited for use as a filter material or an adsorbent. The porous, crystallized aromatic polycarbonate and the shaped porous, crystallized polycarbonate of the present invention can also be readily molded by a melt process into an article useful as engineering plastics, such as an optical element and an electronic component, which is appreciated since it is free of impurities, such as chlorine-containing compounds, and has excellent properties.
BACKGROUND ART
In recent years, aromatic polycarbonates have been widely employed in various fields as engineering plastics which have excellent heat resistance, impact resistance and transparency. Various studies have been made with respect to processes for producing aromatic polycarbonates. Up to now processes, such as one utilizing interfacial condensation polymerization of an aromatic dihydroxy compound, such as 2,2-bis(4-hydroxyphenyl)propane (hereinafter frequently referred to as "bisphenol A"), with phosgene (hereinafter frequently referred to as the "phosgene process"), have been commercially practiced. In the phosgene process, a mixed solvent of water or an aqueous alkali solution and a water-immiscible organic solvent are generally used. Commercially, a mixed solvent of an aqueous sodium hydroxide solution and methylene chloride are employed. As a catalyst for polymerization, a tertiary amine or a quaternary ammonium compound is employed. By-produced hydrogen chloride is removed as a salt with a base.
However, in the interfacial condensation polymerization process employing phosgene, (1) toxic phosgene must be used; (2) due to the by-produced chlorine-containing compounds, such as hydrogen chloride and sodium chloride, the apparatus used is likely to be corroded; (3) it is difficult to remove impurities which adversely influence the polymer properties, such as sodium chloride, from the polymer; and (4) since methylene chloride (which is generally used as a reaction solvent) is a good solvent for polycarbonate and has a strong affinity to polycarbonate, methylene chloride inevitably remains in produced polycarbonate. Removal of the remaining methylene chloride on a commercial scale is extremely costly, and complete removal of the remaining methylene chloride from the obtained polycarbonate is almost impossible. Further, it is noted that the methylene chloride remaining in the polymer is likely to be decomposed, e.g., by heat at the time of molding, thereby forming hydrogen chloride, which not only causes corrosion of a molding machine but also lowers the quality of the polymer. Furthermore, when it is intended to produce a polycarbonate having a high molecular weight (e.g., number average molecular weight of 15,000 or more), a methylene chloride solution of such a polycarbonate has an extremely high viscosity, thereby making agitation of the solution difficult. Additionally, sticky polymer solution is produced, and hence it becomes extremely difficult to separate the polymer from methylene chloride. Therefore, commercial production of a high quality, high mole
REFERENCES:
patent: 4661528 (1987-04-01), Rei
patent: 4663359 (1987-05-01), Rei
patent: 4686239 (1987-08-01), Rei
Fukawa Isaburo
Fukuoka Shinsuke
Komiya Kyosuke
Sasaki Yoro
Asahi Kasei Kogyo Kabushiki Kaisha
Foelak Morton
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