Abstract: A process for purifying a polycarbonate resin solution which comprises passing a water-in-oil dispersion type (W/O) emulsion composed of a mixture of an organic solvent solution containing a polycarbonate resin with a aqueous solution and having water particles with an average diameter of 1 to 100 &mgr;m in an oil through a metallic filter having a filtering precision of 10 to 200 &mgr;m, and then, settling the mixture for 1 to 30 minutes to perform separation between the organic solvent solution containing a polycarbonate resin and the aqueous solution containing contaminations.

Abstract: In a process for producing a halogenated polycarbonate molded article from a powder or pellets of a halogenated polycarbonate resin or composition thereof by means of injection molding using an injection molding machine, the improvement wherein the injection molding machine comprises a cylinder whose inner circumferential wall being made of a corrosion-resistant and abrasion-resistant alloy comprising alloy component (1), (2), or (3) given below, and a screw part made of a steel having a metal coating formed by hard chromium plating or hard nickel plating or made of SUS420, SUS440, Hastelloy C, or a steel comprising alloy component (4) given below:______________________________________ Alloy component (1): C: 0.5-2 wt % Si: 1-5 wt % B: 0.5-5 wt % Ni: 10-25 wt % Cr: 20-35 wt % W: 10-25 wt % Cu: 0.5 -5 wt % Remainder: Co and unavoidable impurities, Alloy component (2): Si: 0.2-4 wt % Mn: 0.

Abstract: Disclosed is a process for producing powder aggregate particle of high molecular weight polycarbonate resin which comprises adding a poor solvent to a solution containing 3 to 8% by weight of high molecular weight polycarbonate resin having a viscosity average molecular weight of at least 70,000 in a solvent in a ratio of the poor solvent to the solution of the polycarbonate resin of 0.2 to 0.6 by volume, continuously pouring the resulting mixture into water heated to a higher temperature than a boiling point of a solvent of the solution of the polycarbonate resin, thereby suspending the mixture in the warm water, distilling out the solvent and the poor solvent from the mixture, thereby obtaining a slurry of the polycarbonate resin and water in the following ratio by volume:Solvent/polycarbonate resin.ltoreq.0.55Solvent/poor solvent.ltoreq.0.7,and recycling at least a portion of the slurry to a wet-process pulverizer, while further distilling out the solvent and the poor solvent from the slurry.

Abstract: A polycarbonate resin comprising either a structural unit derived from a spiro ring-containing dihydric phenol, or such a structural unit and a structural unit derived from a dihydric phenol, and a process for producing the same. The polycarbonate resin has excellent flowability and moldability, and also improved optical properties (low refractive index, large Abbe number, etc.), and can be advantageously used in various fields, e.g., as a material for molded articles for optical use and other precision molded articles.

Abstract: This invention provides 3,9-bis[1,1-dimethyl-2-(4'-hydroxybenzoyloxy)ethyl]-2,4,8,10-tetraoxaspiro [5,5]-undecane represented by the formula: ##STR1## a process for preparing the above compound by a transesterification reaction of 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane with alkyl 4-hydroxybenzoate.

Abstract: This invention provides 2,2-bis[4-(4'-hydroxybenzoyloxy)cyclohexyl]propane represented by the formula: ##STR1## a process for preparing the above compound by a transesterification reaction of 2,2-bis(4-hydroxycyclohexyl)propane with alkyl 4-hydroxybenzoate.