The present invention relates to a purifying apparatus for polycarbonate polyols, especially for removal of cyclic alkylene carbonates, comprising an evaporation unit (1) provided with a heater (10) and having an inlet (6) disposed at the top end thereof and a bottoms vessel (11), and a stripping column (2) connected downstream of the evaporation unit (1) and having a top (21) and a bottom (23), wherein a feed (5) for the polycarbonate polyol to be purified opens into the inlet (6) to the evaporation unit (1) and a gas outlet line (12) and a connecting line which opens into the top (21) of the stripping column (2) and is equipped with a pump (18) depart from the evaporation unit (1), and wherein a gas inlet line (24) for an inert gas opens into the bottom (23) of the stripping column (2) and a product line (27) for the purified polycarbonate polyol departs from the bottom (23) of the stripping column (2) and a gas outlet line (25) departs from the top (21) of the stripping column (2). The invention additionally relates to a process for purifying polycarbonate polyols with such a purifying apparatus.

In an embodiment, a process of purifying a polycarbonate from an interfacial polymerization product mixture comprising an aqueous phase and an organic phase comprising a first organic solvent, the polycarbonate, a catalyst, and ions, the process comprises: separating the aqueous phase and the organic phase to form a separated aqueous feed stream and a separated organic stream; extracting the catalyst and the ions from the separated organic stream to form a purified polycarbonate stream and an extracted aqueous feed stream, wherein at least one of the separated aqueous feed stream and the extracted aqueous feed stream comprise an organic portion and an aqueous portion; purifying an aqueous stream comprising one or both of the separated aqueous feed stream and the extracted aqueous feed stream by adjusting a viscosity of the organic portion to be less than or equal to 40 centipoise by adding a second organic solvent to the aqueous stream to form a combined stream; optionally, adjusting a ratio of the aqueous portion to the organic portion to 1.0 to 20.0 by adding an aqueous solution to the aqueous stream; and separating the combined stream to form a purified aqueous stream, wherein less than or equal to 3 vol % of the purified aqueous stream is the organic portion.

In an embodiment, a process of purifying a polycarbonate comprises: polymerizing a dihydroxy compound and a carbonate source via an interfacial reaction in the presence of a catalyst to form a product mixture comprising an aqueous phase and an organic phase, wherein the organic phase comprises the polycarbonate, the catalyst, ions, and a solvent having a boiling point T.sub.b; heating the product mixture to greater than or equal to T.sub.b; separating the aqueous phase and the organic phase at a temperature greater than or equal to T.sub.b to form a separated organic phase and a separated aqueous phase; extracting the catalyst from the separated organic phase; and extracting the ions from the separated organic phase; wherein if a centrifuge is used in the extracting of the catalyst, the extracting of the ions, or both, the process further comprises cooling a stream entering the centrifuge to less than T.sub.b.

In another embodiment, a process of purifying an interfacially polymerized polycarbonate from a feed comprising an aqueous phase and an organic phase comprising an organic solvent, the interfacially polymerized polycarbonate, a catalyst, and ions, can comprise: separating the aqueous phase and the organic phase from the feed, wherein during the separating the feed is subjected to at least one of: energy of less than or equal to 0.5 kJ/kg of feed, a shear rate of less than 150,000 S.sup.1, and centrifugal forces of 100 to 2,000 g-force; to form a purified aqueous phase and a purified organic phase comprising a purified polycarbonate.

A method of decreasing aldehyde content in a polymeric material uses a compound (Z) which includes a moiety of formula (I): wherein each R.sup.1 and R.sup.2 independently represents a substituent, n1 is 0 to 4 and n2 is 0 to 4; wherein X is selected from the group comprising C, N, P, O and S atoms; and each of the two benzene rings includes a moiety formula (A) and a moiety formula (B): NH wherein the carbon atom of moiety (A) and the nitrogen atom of moiety (B) are separated by at least one and not more than two atoms.

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A method of producing polycarbonate-based polymer microparticles including forming an emulsion in a system in which a polycarbonate-based polymer (A), a polymer (B) different from the polycarbonate-based polymer (A) and an organic solvent (C) are dissolved and mixed together and which causes phase separation into two phases of a solution phase having the polycarbonate-based polymer (A) as its main component and a solution phase having the polymer (B) different from the polycarbonate-based polymer (a) as its main component, and contacting a poor solvent for the polycarbonate-based polymer (A) with the emulsion at a temperature of 80 C. or higher to thereby precipitate microparticles of the polycarbonate-based polymer (A).

Systems and methods for purifying or recycling polymeric materials such as polycarbonates are disclosed. Such methods may include performing two or more extractions using differing solvent media to remove non-target materials and attain a purified composition of a target polymer. Other steps including dissolution, precipitation, filtration, and/or centrifugation may also be performed in the methods of the present invention.

The present disclosure relates to a method for separating an organic zinc catalyst dispersed in a polyalkylene carbonate resin solution by filtering the polyalkylene carbonate resin solution using a composite filtering membrane, which is a composite material comprising a hydroxyl group-containing material and polyolefin material and has a form in which one or both surfaces of the polyolefin material is coated with the hydroxyl group-containing material.

A method for producing a polycarbonate, comprising a polymerization step of polymerizing a dihydroxy compound and a diaryl carbonate, or a prepolymer thereof in a polymerization reactor, a washing step of contacting a discharged vapor containing the hydroxyaryl compound, the diaryl carbonate and the dihydroxy compound, discharged from the polymerization reactor in the polymerization step, with a washing liquid in a scrubber, and a condensation step of condensing the discharged vapor washed in the washing step, wherein at least a portion of a bottom liquid of the scrubber in the washing step is supplied to the polymerization reactor.

The present invention is capable of providing a method for producing a refined polycarbonate resin by removing unreacted dihydroxy compounds contained as impurities in a polycarbonate resin following polymerization. This production method includes: (i) a step for dissolving said polycarbonate resin following polymerization in an organic solvent, and filtering to prepare a 1-30 mass % resin solution or (ii) a step for preparing, by means of interfacial polymerization, a 1-30 mass % resin solution in which a polycarbonate resin is dissolved in an organic solvent following interfacial polymerization; and a step for passing the obtained resin solution through a column chromatograph to remove unreacted dihydroxy compounds contained as impurities in the polycarbonate resin following polymerization.