Polycarbonate

Abbreviated as PC, it is a polyester made from carbon dioxide and glycol or a dihydric phenol and is represented by the general formula (R is a divalent aliphatic or aromatic hydrocarbon group, and in the narrow sense refers to polycarbonate obtained from bisphenol A and phosgene). A linear polymer with -O-CO-O- bonds was synthesized in 1956 by H. Schnell of Bayer AG in West Germany. Typical production methods include transesterification and polycondensation with phosgene; for example, bisphenol and an excess of diphenyl carbonate are heated to 180-220°C and the phenol is removed from the reaction system at a reduced pressure of 2.7-4.0 kPa. A catalyst is added if necessary. It is difficult to obtain a product with an extremely high degree of polymerization, but conversely, there is a tendency to obtain a product with good moldability.

In the reaction between bisphenol and phosgene, hydrogen chloride is eliminated, so a collector must be present; there are methods using an alkaline aqueous solution or a pyridine system. The former seems to be the more widely used industrially. It has excellent mechanical properties, weather resistance, and heat resistance, good dimensional stability, flame retardancy, and transparency, but it is slightly hygroscopic. Its resistance to organic solvents such as methanol, ketones, ethers, and aromatic hydrocarbons is not very good. Dichloromethane, dioxane, and chlorobenzene are good solvents. Taking advantage of its good dimensional stability, it can be used for mechanical parts, electrical parts, photographic film base, optical recording materials (CDs), etc. [CAS 24936-68-3]

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

略称PC．炭酸とグリコールまたは二価フェノールとからなるポリエステルで，一般式で表される(Rは二価の脂肪族または芳香族炭化水素基で，狭義にはビスフェノールAとホスゲンから得られるポリカーボネートをさす)．-O-CO-O-結合をもつ線状重合体は，1956年，西ドイツBayer社のH. Schnellによって合成された．代表的製法としては，エステル交換法とホスゲンによる重縮合とがあり，たとえば，ビスフェノールとジフェニルカルボナートの過剰とを180～220 ℃ に加熱し，2.7～4.0 kPa の減圧でフェノールを反応系外に除去する．必要に応じて触媒を添加する．重合度の非常に大きなものは得がたいが，逆に成形性のよいものが得られる傾向がある．

ビスフェノールとホスゲンの反応では塩化水素が脱離するので，その捕集剤を共存させる必要があり，アルカリ水溶液系やピリジン系で行う方法がある．工業的には前者が採用されているようである．機械的性質，耐候性，耐熱性がすぐれ，寸法安定性がよく，難燃性，透明であるが，わずかながら吸湿性がある．メタノール，ケトン，エーテル，芳香族炭化水素などの有機溶剤に対する耐溶剤性はあまりよくない．また，ジクロロメタン，ジオキサン，クロロベンゼンなどが好溶媒である．寸法安定性のよい点を利用して，機械部品，電気部品，写真フィルムベース，光記録材料(CD)などに利用できる．[CAS 24936-68-3]

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