# US 7,041,775 B2 · Method for preparing a polycarbonate oligomer mixture at low temperature for manufacturing polycarbonate > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,041,775 B2 - Document ID: US7041775B2 - Status: Granted - Kind: B2 - Application number: 10/830,163 - Filed: 2004-04-21 - Published: 2005-10-20 - Granted: 2006-05-09 - Earliest claimed: 2004-04-20 - Assignees: General Electric Company - Inventors: Maria Tomas Martinez; Alberto Nisoli; Alfredo Lopez Carretero; Ganesh Kailasam; David Domingo; Patrick Joseph McCloskey - Web page: https://patentgrep.com/patent/US7041775B2 ## CPC - C08G 64/307: {and phenols} - B01J 19/18: Stationary reactors having moving elements inside (B01J19/08, B01J19/26 take precedence) - B01J 19/1806: {resulting in a turbulent flow of the reactants, such as in centrifugal-type reactors, or having a high Reynolds-number} - B01J 19/1887: {forming a thin film} - B01J 19/20: in the form of helices, e.g. screw reactors - C08G 64/205: {characterised by the apparatus used} - B01J 2219/00031: Semi-batch or fed-batch processes - B01J 2219/0004: Processes in series - B01J 2219/00083: Coils - B01J 2219/00094: Jackets - B01J 2219/00166: controlling the residence time inside the reactor vessel - B01J 2219/00184: controlling the weight of reactants in the reactor vessel - B01J 2219/00186: controlling the composition of the reactive mixture - C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS - B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS ## Abstract The present invention provides a method of making polycarbonate oligomers, polycarbonate, molded articles formed from polycarbonate, and an apparatus for making polycarbonate. An oligomer mixture is first prepared by the steps of providing an equilibration system comprising a vessel, a reaction mixture contained within the vessel, and means for mixing the reaction mixture contained within the vessel wherein the reaction mixture comprises a melted activated diaryl carbonate composition, and a catalyst present in sufficient amount to initiate an oligomerization reaction between a dihydroxy composition and the activated diaryl carbonate to form polycarbonate oligomers. The method further includes the steps of introducing a melted dihydroxy composition to the reaction mixture contained within the equilibration system, maintaining the reaction mixture contained within the vessel at an oligomerization temperature, said oligomerization temperature being below the melting point the dihydroxy composition, and sufficiently high to allow formation of a homogeneous melt within the vessel, and continuously drawing off a product stream from the equilibration system, wherein the product stream comprises a polycarbonate oligomer mixture. This polycarbonate oligomer mixture is suitably used as a feed stock for producing polycarbonate in a polycondensation system. The polycarbonate is suitably used for the preparation of molded articles. ## Claims ### Claim 1 A method of preparing a polycarbonate oligomer mixture comprising the steps of: (a) providing an equilibration system comprising a vessel, a reaction mixture contained within the vessel, and means for mixing the reaction mixture contained within the vessel wherein the reaction mixture comprises, i. a melted activated diaryl carbonate composition, and ii. a catalyst present in sufficient amount to initiate an oligomerization reaction between a dihydroxy composition and the activated diaryl carbonate to form polycarbonate oligomers, (b) introducing a melted dihydroxy composition to the reaction mixture contained within the equilibration system, (c) maintaining the reaction mixture contained within the vessel at an oligomerization temperature, said oligomerization temperature being below the melting point of the dihydroxy composition, and sufficiently high to allow formation of a homogeneous melt within the vessel, and (d) continuously drawing off a product stream from the equilibration system, wherein the product stream comprises a polycarbonate oligomer mixture. ### Claim 2 (depends on 1) The method of claim 1, wherein the melted dihydroxy compound is provided from a melting apparatus, and wherein the dihydroxy compound has a total residence time in the melting apparatus and the equilibration system such that the polycarbonate oligomer mixture has a Yellowness Index (YI) of less than 10. ### Claim 3 (depends on 2) The method of claim 2, wherein the residence time in the melting apparatus is less than 30% of the residence time in the equilibration system. ### Claim 4 (depends on 2) The method of claim 2, wherein the melted dihydroxy compound is provided from a melting apparatus, and wherein the dihydroxy compound has a total residence time in the melting apparatus and the equilibration system such that the polycarbonate oligomer mixture has a Yellowness Index (YI) of less than 5. ### Claim 5 (depends on 2) The method of claim 2, wherein the melting apparatus comprises a thin film turbulizing melter. ### Claim 6 (depends on 1) The method of claim 1, wherein the reaction mixture is maintained at an oligomerization temperature of between 140° C. and 300° C. ### Claim 7 (depends on 1) The method of claim 1, wherein the dihydroxy composition comprises bisphenol A (BPA). ### Claim 8 (depends on 7) The method of claim 7, wherein the dihydroxy composition further comprises one or more additional dihydroxy compounds different from BPA. ### Claim 9 (depends on 1) The method of claim 1, wherein the dihydroxy composition consists essentially of BPA. ### Claim 10 (depends on 1) The method of claim 1, wherein the activated diaryl carbonate composition comprises bismethylsalicylcarbonate (BMSC). ### Claim 11 (depends on 10) The method of claim 10, wherein the activated diaryl carbonate composition further comprises one or more additional diaryl carbonate compounds different from BMSC. ### Claim 12 (depends on 10) The method of claim 10, wherein the dihydroxy composition comprises BPA. ### Claim 13 (depends on 1) The method of claim 1, wherein the activated diaryl carbonate composition consists essentially of BMSC. ### Claim 14 (depends on 1) The method of claim 1, wherein the dihydroxy composition is introduced to the reaction mixture in a melted state and is melted by means which prevent substantial degradation of the dihydroxy composition. ### Claim 15 (depends on 1) The method of claim 1, wherein the diaryl carbonate composition is melted by means which prevent substantial degradation of the diaryl carbonate. ### Claim 16 (depends on 1) The method of claim 1, wherein the equilibration system is operated at atmospheric pressure under a substantially oxygen-free atmosphere. ### Claim 17 (depends on 1) The method of claim 1, wherein the means for mixing the reaction mixture comprises a recirculation feed whereby a portion of the polycarbonate oligomer mixture is recirculated to the equilibration system. ### Claim 18 (depends on 17) The method of claim 17, wherein the recirculation feed flow rate is higher than the feed flow rate of dihydroxy composition. ### Claim 19 (depends on 17) The method of claim 17, wherein the dihydroxy composition is combined with the recirculation feed prior to introduction to the equilibration system. ### Claim 20 (depends on 1) The method of claim 1, wherein the dihydroxy composition and the diaryl carbonate composition are present in molar ratios of 0.25:1 to 3:1. ### Claim 21 (depends on 20) The method of claim 20, wherein the dihydroxy composition and the diaryl carbonate composition are present in molar ratios of 0.9:1 to 1.5:1. ### Claim 22 (depends on 1) The method of claim 1, wherein the reaction mixture is maintained at a temperature of 10° C. lower than the melting temperature of the highest melting dihydroxy compound. ### Claim 23 (depends on 22) The method of claim 22, wherein the reaction mixture is maintained at a temperature of 30° C. lower than the melting temperature of the highest melting dihydroxy compound. ### Claim 24 (depends on 23) The method of claim 23, wherein the reaction mixture is maintained at a temperature of 100° C. lower than the melting temperature of the highest melting dihydroxy compound. ### Claim 25 A method for preparing polycarbonate, comprising the steps of: (i) preparing a polycarbonate oligomer mixture comprising the steps of: (a) providing an equilibration system comprising a vessel, a reaction mixture contained within the vessel, and means for mixing the reaction mixture contained within the vessel wherein the reaction mixture comprises, i. a melted activated diaryl carbonate composition, and ii. a catalyst present in sufficient amount to initiate an oligomerization reaction between a dihydroxy composition and the activated diaryl carbonate to form polycarbonate oligomers, (b) introducing a melted dihydroxy composition to the reaction mixture contained within the equilibration system, (c) maintaining the reaction mixture contained within the vessel at an oligomerization temperature, said oligomerization temperature being below the melting point of the dihydroxy composition, and sufficiently high to allow formation of a homogeneous melt within the vessel, and (d) continuously drawing off a product stream from the equilibration system, wherein the product stream comprises a polycarbonate oligomer mixture, and (ii) introducing the polycarbonate oligomer mixture from step (i) to a polycondensation system to build molecular weight, thereby producing polycarbonate. ### Claim 26 (depends on 25) The method of claim 25, wherein the melted dihydroxy compound is provided from a melting apparatus, and wherein the dihydroxy compound has a total residence time in the melting apparatus and the equilibration system such that the polycarbonate oligomer mixture has a Yellowness Index (YI) of less than 10. ### Claim 27 (depends on 26) The method of claim 26, wherein the residence time in the melting apparatus is less than 30% of the residence time in the equilibration system. ### Claim 28 (depends on 26) The method of claim 26, wherein the melted dihydroxy compound is provided from a melting apparatus, and wherein the dihydroxy compound has a total residence time in the melting apparatus and the equilibration system such that the polycarbonate oligomer mixture has a Yellowness Index (YI) of less than 5. ### Claim 29 (depends on 26) The method of claim 26, wherein the melting apparatus comprises a thin film turbulizing melter. ### Claim 30 (depends on 25) The method of claim 25, wherein the reaction mixture is maintained at an oligomerization temperature of between 140° C. and 300° C. ### Claim 31 (depends on 25) The method of claim 25, wherein the dihydroxy composition comprises BPA. ### Claim 32 (depends on 31) The method of claim 31, wherein the dihydroxy composition further comprises one or more the additional dihydroxy compounds different from BPA. ### Claim 33 (depends on 25) The method of claim 25, wherein the dihydroxy composition consists essentially of BPA. ### Claim 34 (depends on 25) The method of claim 25, wherein the activated diaryl carbonate composition comprises BMSC. ### Claim 35 (depends on 34) The method of claim 34, wherein the activated diaryl carbonate composition further comprises one or more additional activated diaryl carbonate compounds different from BMSC. ### Claim 36 (depends on 34) The method of claim 34, wherein the dihydroxy composition comprises BPA. ### Claim 37 (depends on 25) The method of claim 25, wherein the activated diaryl carbonate composition consists essentially of BMSC. ### Claim 38 (depends on 25) The method of claim 25, wherein the dihydroxy composition is melted by means which prevent substantial degradation of the dihydroxy composition. ### Claim 39 (depends on 25) The method of claim 25, wherein the activated diaryl carbonate composition is melted by means prevent substantial degradation of the activated diaryl carbonate. ### Claim 40 (depends on 25) The method of claim 25, wherein the equilibration system is operated at atmospheric pressure. ### Claim 41 (depends on 25) The method of claim 25, wherein the means for mixing the reaction mixture comprises a recirculation feed whereby a portion of the polycarbonate oligomer mixture is recirculated to the equilibration system. ### Claim 42 (depends on 41) The method of claim 41, wherein the recirculation feed flow rate is higher than the feed flow rate of dihydroxy composition. ### Claim 43 (depends on 41) The method of claim 41, wherein the dihydroxy composition is combined with the recirculation feed prior to introduction to the equilibration system. ### Claim 44 (depends on 25) The method of claim 25, wherein the dihydroxy composition and the activated diaryl carbonate composition are present in molar ratios of 0.25:1 to 3:1. ### Claim 45 (depends on 44) The method of claim 44, wherein the dihydroxy composition and the activated diaryl carbonate composition are present in molar ratios of 0.9:1 to 1.5:1. ### Claim 46 (depends on 25) The method of claim 25, further comprising the step of filtering the polycarbonate oligomer mixture prior to introducing it to the polycondensation system. ### Claim 47 (depends on 25) The method of claim 25, wherein the reaction mixture is maintained at a temperature of 10° C. lower than the melting temperature of the highest melting dihydroxy compound. ### Claim 48 (depends on 47) The method of claim 47, wherein the reaction mixture is maintained at a temperature of 30° C. lower than the melting temperature of the highest melting dihydroxy compound. ### Claim 49 (depends on 48) The method of claim 48, wherein the reaction mixture is maintained at a temperature of 100° C. lower than the melting temperature of the highest melting dihydroxy compound. ### Claim 50 A molded article formed from polycarbonate produced by the method, comprising the steps of: (i) preparing a polycarbonate oligomer mixture comprising the steps of: (a) providing an equilibration system comprising a vessel, a reaction mixture contained within the vessel, and means for mixing the reaction mixture contained within the vessel wherein the reaction mixture comprises, i. a melted activated diaryl carbonate composition, and ii. a catalyst present in sufficient amount to initiate an oligomerization reaction between a dihydroxy composition and the activated diaryl carbonate to form polycarbonate oligomers, (b) introducing a melted dihydroxy composition to the reaction mixture contained within the equilibration system, (c) maintaining the reaction mixture contained within the vessel at an oligomerization temperature, said oligomerization temperature being below the melting points of the dihydroxy composition, and sufficiently high to allow formation of a homogeneous melt within the vessel, and (d) continuously drawing off a product stream from the equilibration system, wherein the product stream comprises a polycarbonate oligomer mixture, and (ii) introducing the polycarbonate oligomer mixture from step (i) to a polycondensation system to build molecular weight, thereby producing polycarbonate, and (iii) forming a molded article from the polycarbonate. ### Claim 51 A method for making a molded article formed from polycarbonate produced by the method, comprising the steps of: (i) preparing a polycarbonate oligomer mixture comprising the steps of: (a) providing an equilibration system comprising a vessel, a reaction mixture contained within the vessel, and means for mixing the reaction mixture contained within the vessel wherein the reaction mixture comprises, i. a melted activated diaryl carbonate composition, and ii. a catalyst present in sufficient amount to initiate an oligomerization reaction between a dihydroxy composition and the activated diaryl carbonate to form polycarbonate oligomers, (b) introducing a melted dihydroxy composition to the reaction mixture contained within the equilibration system, (c) maintaining the reaction mixture contained within the vessel at an oligomerization temperature, said oligomerization temperature being below the melting point of the dihydroxy composition, and sufficiently high to allow formation of a homogeneous melt within the vessel, and (d) continuously drawing off a product stream from the equilibration system, wherein the product stream comprises a polycarbonate oligomer mixture, and (ii) introducing the polycarbonate oligomer mixture from step (a) to a polycondensation system to build molecular weight, thereby producing polycarbonate, and (iii) forming a molded article from the polycarbonate. ### Claim 52 An apparatus for making polycarbonate comprising: (a) one or more melters containing either separately or in combination an activated diaryl carbonate composition and a dihydroxy composition; (b) a equilibration vessel connected to the one or more melters and receiving melted activated diaryl carbonate composition and melted dihydroxy composition therefrom via one or more monomer feed lines; (c) a feed line connected to the equilibration vessel and containing a polymerization catalyst; (d) a polycondensation system, wherein the polycondensation system is connected at one end to the equilibration vessel; and (e) a transfer line connecting the equilibration vessel to the polycondensation system and containing an oligomer stream; wherein the equilibration vessel has a size and the apparatus has a flow rate that are selected in combination such that the residence time of the activated diaryl carbonate composition and the dihydroxy composition in the equilibration vessel is sufficient to produce polycarbonate oligomers within the equilibration vessel. ### Claim 53 (depends on 52) The apparatus of claim 52, wherein the activated diaryl carbonate composition comprises BMSC. ### Claim 54 (depends on 53) The apparatus of claim 53, wherein the activated diaryl carbonate composition further comprises one or more additional activated diaryl carbonate compositions different from BMSC. ### Claim 55 (depends on 52) The apparatus of claim 52, wherein the activated diaryl carbonate composition consists essentially of BMSC. ### Claim 56 (depends on 52) The apparatus of claim 52, wherein the one or more melters are selected such that substantial degradation of the dihydroxy composition does not occur in the one or more melters. ### Claim 57 (depends on 52) The apparatus of claim 52, wherein the one or more melters are selected such that substantial degradation of the activated diaryl carbonate composition does not occur in the one or more melters. ### Claim 58 (depends on 52) The apparatus of claim 52, further comprising a recirculation feed line extending from the transfer line to the equilibration vessel and containing a portion of the oligomer stream, whereby a portion of the oligomer stream is recirculated to the equilibration vessel. ### Claim 59 (depends on 58) The apparatus of claim 58, wherein the one or more monomer feed lines are combined with the recirculation feed line. ### Claim 60 (depends on 52) The apparatus of claim 52, wherein the one or more melters are selected from the group consisting of thin film melters, jacketed tubular melters with internal agitation, jacketed agitated vessels, jacketed agitated vessels with a recirculation line with or without heat exchanger, jacketed screw conveyors, two phase shell and tube heat exchangers, extruders, and two phase static mixers. ### Claim 61 A method of preparing a polycarbonate oligomer mixture comprising the steps of: (a) providing an equilibration system comprising a vessel, a reaction mixture contained within the vessel, and means for mixing the reaction mixture contained within the vessel wherein the reaction mixture comprises, i. a melted activated diaryl carbonate composition, and ii. a catalyst present in sufficient amount to initiate an oligomerization reaction between a dihydroxy composition and the activated diaryl carbonate to form polycarbonate oligomers, (b) introducing a melted dihydroxy composition to the reaction mixture contained within the equilibration system, wherein the dihydroxy composition is selected from the group consisting of 2,6-dihydroxy naphthalene; 2,6-dihydroxy-3-methyl naphthalene; and 2,6-dihydroxy-3-phenyl naphthalene, and (c) continuously drawing off a product stream from the equilibration system, wherein the product stream comprises a polycarbonate oligomer mixture, wherein the melted dihydroxy compound is provided from a melting apparatus, and wherein the dihydroxy compound has a total residence time in the melting apparatus and the equilibration system such that the polycarbonate oligomer mixture has a Yellowness Index (YI) of less than 10.