Reference

Controlling the molecular weight of aromatic polycarbonates

Controlling the molecular weight of aromatic polycarbonates. Baggett, Joseph M. (Dow Chemical Co., USA). U.S. US 4020045 26 Apr 1977, 4 pp. (English). (United States of America). CODEN: USXXAM. CLASS: IC: C08G017-13. NCL: 260047000XA. APPLICATION: US 76-661672 26 Feb 1976. DOCUMENT TYPE: Patent CA Section: 35 (Synthetic High Polymers) In the prepn. of arom. polycarbonates from carbonyl halides and dihydric phenols by interfacial polymn., the mol. wt. of the product was controlled by adding metallic sulfites, e.g. alkali metal sulfites, pyrosulfites, and hyposulfites as chain terminators. Thus, 75 mL p-bisphenol A, 3 g anhydr. Na2SO3, 276 g H2O, 34 mL 35% caustic soln., 214 mL methylene chloride, 0.4 mL triethylamine, and 42 g phosgene were heated 30 min at 25.degree., sepd. to H2O and methylene chloride layers, and the methylene chloride layer filtered and pptd. with n-hexane to remove the white polycarbonate (I) [25971-63-5] particles. I was filtered, dried 8 h at 110.degree., and molded in a press at 600.degree.F to give a tough, high-impact type, clear plastic.

Nonopaque flame-retardant polycarbonate compositions

Nonopaque flame-retardant polycarbonate compositions. Mark, Victor (General Electric Co., USA). Ger. Offen. DE 2647271 5 May 1977, 22 pp. (German). (Germany).Some chemicals with cas registry numbers like 63295-41-0 are also used. CODEN: GWXXBX. CLASS: IC: C08L069-00. PRIORITY: US 75-626934 29 Oct 1975. DOCUMENT TYPE: Patent CA Section: 36 (Plastics Manufacture and Processing) A polycarbonate was mixed with 0.01-1.0% Na 2,5-dichlorothiophene-3-sulfonate (I) [56878-68-3], K dibenzofuran-3-sulfonate [63295-39-6], K 2,3,5-tribromothiophene-4-sulfonate [63295-40-9], Na pyridine-3-sulfonate [15521-77-4], or a similar compd. to prep. polycarbonates with good fire resistance and transparency. Thus, a bisphenol A-phosgene copolymer [25971-63-5] contg. 0.01% I had light transmission 86% and good fire resistance (UL 94 rating V-O). .