Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Patent
1998-03-19
1999-08-24
Mosley, Terressa
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
528198, 528199, C08G 6400
Patent
active
059425946
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a polycarbonate and a process for producing the polycarbonate. More particularly, the present invention relates to a polycarbonate exhibiting excellent fluidity and moisture resistance and a process for efficiently producing the polycarbonate by transesterification in the presence of a specific catalyst.
BACKGROUND ART
Polycarbonates are engineering plastics having excellent impact resistance, heat resistance, and transparency and widely used as various types of mechanical parts, optical disks, and automobile parts. Recently, higher fluidity is required in the field of optical disks.
In response to this requirement, a polycarbonate which is obtained by interfacial polycondensation using a solvent such as methylene chloride and has a chain end structure modified with a group such as cumylphenoxy group has been proposed (Japanese Patent Application Laid-Open No. Heisei 1(1989)-245016). However, complete removal of impurities, such as sodium and chlorine, from the polycarbonate obtained by the interfacial polycondensation is difficult, and the polycarbonate is not satisfactory for optical applications.
On the other hand, as the process for obtaining a polycarbonate containing decreased amounts of impurities without using any solvent, a transesterification process (a melt polymerization process) is known. As the process for producing a polycarbonate having cumylphenoxy group at the chain ends in accordance with this transesterification process, for example, a process in which a catalyst comprising a combination of a basic compound containing nitrogen, an alkali metal compound or an alkaline earth metal compound, and boric acid is used as the polymerization catalyst (Japanese Patent Application Laid-Open No. Heisei 2(1990)-175723) and a process in which polymerization is conducted in the presence of an alkali metal compound or an alkaline earth metal compound used as the catalyst, and then an acidic compound is added (Japanese Patent Application Laid-Open No. Heisei 5(1993)-9287) have been proposed. However, polycarbonates obtained in accordance with these processes have a problem in that cracks are formed at high temperatures in high moisture and strength is decreased.
DISCLOSURE OF THE INVENTION
Under the above circumstances, the present invention has an object to provide a polycarbonate exhibiting excellent fluidity and moisture resistance (resistance to formation of cracks in steam) and a process for producing this polycarbonate efficiently.
As the result of extensive studies by the present inventors on polycarbonates exhibiting excellent fluidity and moisture resistance, it was found that the unit of a phenyl salicylate structure contained in the main chain in a small amount causes decrease in the moisture resistance (resistance to formation of cracks in steam), that a polycarbonate exhibiting excellent moisture resistance can be obtained by suppressing the content of this unit to a specific value or less, and that a polycarbonate satisfying this condition and having p-cumylphenoxy group, phenoxy group, and hydroxyl group in specific relative amounts at the chain ends exhibits particularly excellent fluidity and moisture resistance. It was also found that the above polycarbonates can be obtained efficiently by the transesterification process using a specific catalyst. The present invention has been completed on the basis of these knowledges.
Accordingly, the present invention provides: represented by general formula (I): ##STR3## wherein R.sup.1 and R.sup.2 each represents hydrogen atom or an alkyl group having 1 to 7 carbon atoms, may be the same with or different from each other, and may be bonded to each other to form a ring structure; contains 100 ppm by weight or less of a unit of a phenyl salicylate structure expressed by formula (II): ##STR4## in the main chain; and has a viscosity-average molecular weight of 10,000 or more; and p-cumylphenoxy group, 1 to 94% by mol of phenoxy group, and 1 to 94% by mol of hydroxyl group at the chain ends.
The
Ishikawa Yasuhiro
Nakae Mitsugu
Sato Sadayuki
Idemitsu Kosan Co. Ltd.
Mosley Terressa
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