Patent GB-897114-A (GB)
Title: Process for the production of high molecular weight polycarbonates
IPC: C08G64/24
Filed: 1960-04-06
Abstract: Spherically-shaped thermoplastic polycarbonate particles with a diameter of about 10-2,000 m  are made by (1) polycondensing an organic dihydroxy compound with phosgene or a bis-chlorocarbonic acid ester of an organic dihydroxy compound in a dispersed two-phase system wherein an aqueous alkaline solution or suspension of the dihydroxy compound forms the continuous phase and a solution of the phosgene or the bis-chlorocarbonic acid ester in an organic solvent for the polycarbonate forms the dispersed phase, and wherein the dispersion is stabilized by stirring and by a suitable dispersion adjuvant in such a manner that the dispersed phase remains in the form of small particles even in the last stage of the polycondensation reaction, (2) removing so much solvent from these particles that they do not agglomerate at the termination of the stirring and with removal of the dispersion adjuvant and, (3) separating the particles from the aqueous phase, washing them free of electrolytes and finally completely freeing them from solvent residues.  The solvent may be removed by heating and/or by applying a vacuum, or by precipitation with a non-solvent for the polycarbonate (e.g. ligroin).  The polycarbonate whilst in solution may be treated with an acid to convert the phenate groups into hydroxy groups or with an acylating or alkylating agent.  The polycarbonate may be that of a bis-phenol or a mixture thereof with another dihydric phenol, a dihydric alcohol or a phenolalcohol and the solvent used to dissolve it may be a chlorinated hydrocarbon, an aromatic hydrocarbon, cyclohexanone or anisole.  The dispersion adjuvant may be (a) an anionic, cationic or non-ionic emulsifier, e.g. a sulphonic acid or a salt thereof, a sulphuric acid ester of a hydroxy compound, an emulsifier containing 3- or 5- valent phosphorus, diethylamine oleate, benzyl-dimethyllauryl ammonium chloride, or the reaction products of alkylene oxides with phenols, alcohols or carboxylic acids; (b) a finely-divided inorganic compound such as calcium hydroxide, calcium phosphate, calcium oxalate, calcium carbonate, magnesium hydroxide, aluminium hydroxide, silicon dioxide, titanium dioxide, barium sulphate, silicates, bentonite or talc; (c) a protective colloid such as tragacanth, gum arabic, starch, gelatine, polyacrylic acid, polyethylene oxide, carboxymethyl cellulose or polyvinyl alcohol, or (d) a sulphonated phenol-formaldehyde condensate.  The dispersion adjuvants may be used in admixture with one another or with neutral salts (e.g. sodium chloride) or with Marseilles soap. The polycondensation may also be effected in the presence of (a) a chain-breaker, e.g. p-tertiary-butyl phenol; (b) a reducing agent, e.g. sodium sulphite or tetradecane-1-phosphinate (which also acts as an emulsifier); (c) a catalyst, e.g. a tertiary amine or a quarternary ammonium salt; or (d) a plasticizer, filler, mould-release agent or dye (e.g. copper phthaloxyanine).  Example describe the manufacture of polycarbonates by reacting phosgene with bis-phenol-A or a mixture thereof with 1:1-(4:41-dihydroxydiphenyl)-cyclohexane; or by reacting hexane-1:6-diol-bis-chlorocarbonic acid ester with a mixture of bis-phenol-A and 1:1-(4,41-dihydroxydiphenyl)-cyclohexane.