# US 5,710,238 A · Process for preparing branched polycarbonates by solid state polymerization > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,710,238 A - Document ID: US5710238A - Status: Granted - Kind: A - Application number: 08/653,166 - Filed: 1996-05-24 - Granted: 1998-01-20 - Earliest claimed: 1995-12-29 - Assignees: General Electric Company - Inventors: Swaminathan Sivaram; Sukhendu Bikash Hait - Web page: https://patentgrep.com/patent/US5710238A ## CPC - C08G 64/307: {and phenols} - C08G 64/14: containing a chain-terminating or -crosslinking agent - C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS ## Abstract This invention involves a novel process for preparing branched polycarbonates employing a solid state polycondensation process; specifically, subjecting a linear crystallized oligomer derived from dihydroxydiaryl compound and a diaryl carbonate to solid state polycondensation process by heating the said oligomer at a temperature which is higher than the glass transition temperature but below its melting point in the presence of a multifunctional phenol and an alkali or alkaline metal salt or bisphenol or tetraalkylammonium hydroxide, carboxylate or bicarboxylate catalyst, the reaction being effected under inert atmosphere. ## Claims ### Claim 1 A process for the preparation of branched polycarbonates which comprises subjecting a linear crystallised polycarbonate oligomer prepared by reaction of a dihydroxydiaryl compound with a diaryl carbonate to solid state polycondensation by heating said oligomer at a temperature higher than its glass transition temperature but below its melting point, in the presence of a multifunctional phenol and an alkali or alkaline metal salt of a bisphenol or a tetraalkylammonium hydroxide, carboxylate or bicarboxylate as catalyst, said polycondensation being effected in an inert atmosphere. ### Claim 2 (depends on 1) A process as claimed in claim 1 wherein the linear crystallised polycarbonate oligomer employed has an inherent viscosity in the range of 0.15 to 0.40 dL/g as measured in chloroform at 30.degree. C. ### Claim 3 (depends on 1) A process as claimed in claim 1 wherein the linear crystallised polycarbonate oligomer employed has a hydroxyl number from 5 to 18. ### Claim 4 (depends on 1) A process as claimed in claim 1 wherein the linear crystallised polycarbonate oligomer employed has crystallinity from 5 to 55%. ### Claim 5 (depends on 1) A process as claimed in claim 1 wherein the linear crystallised polycarbonate oligomer employed is derived from a bisphenol chosen from bis(4-hydroxyphenyl) methane; 1,1-bis(4-hydroxyphenyl) ethane; 2,2-bis(4-hydroxy phenyl) propane; 2,2-bis(4-hydroxyphenyl) butane; 2,2-bis(4-hydroxyphenyl) octane; bis(4-hydroxyphenyl)-phenylmethane; 2,2-bis(4-hydroxy-1-methylphenyl) propane; 2,2-bis(4-hydroxy-butylphenyl) propane, 2,2 bis(4-hydroxy-3-bromophenyl) propane, 1,1 -bis(4-hydroxyphenyl) cyclopentane, 1,1-bis(4-hydroxy phenyl) cyclohexane, 4,4'-dihydroxyphenyl ether, 4,4'-dihydroxy-3,3'-dimethyldiphenyl ether, 4,4'-dihydroxydiphenyl sulfoxide, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide and 4,4'-dihydroxydiphenyl sulfone. ### Claim 6 (depends on 1) A process as claimed in claim 1, wherein the diaryl carbonate used is diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate or bis(diphenyl) carbonate. ### Claim 7 (depends on 1) A process as claimed in claim 1, wherein the oligomer is subjected to solid state polycondensation in presence of 0.1 to 2 wt % of a multifunctional phenol. ### Claim 8 (depends on 1) A process as claimed in claim 1, wherein the multifunctional phenol used is chosen from 1,1,1-tris-(4-hydroxyphenyl) ethane ; 1,3,5-tris-(2-hydroxyethyl) cyanuric acid; 4,6-dimethyl-2,4,6-tris-(4-hydroxyphenyl) heptane-2; 2,2-bis-4,4-(4,4"-dihydroxyphenyl)-cyclohexyl propane; 1,3,5-trihydroxybenzene; 1,2,3-trihydroxybenzene; 1,4-bis-(4',4"-dihydroxytriphenylmethyl)-benzene; 2',3',4'-trihydroxy acetophenone; 2,3,4-trihydroxybenzoioc acid; 2,3,4-trihydroxybenzophenone; 2,4,4'-trihydroxybenzophenone; 2',4',6'-trihydroxy-3(4-hydroxyphenyl) propiophenone; pentahydroxyflavone; 3,4,5-trihydroxypyrimidine; 3,4,5-trihydroxyphenylmethyl amine; tetrahydroxy-1,4-quinone hydrate;2,2',4,4' tetrahydroxybenzophenone; and 1,2,5,8 tetrahydoxyanthraquinone. ### Claim 9 (depends on 1) A process as claimed in claim 1, wherein the catalyst used is chosen from disodium salt of bisphenol-A, dipotassium salt of bisphenol-A, tetrabutylammonium hydroxide, tetramethylammonium hydroxide, tetrabutylammonium hydrogen bisbenzoate, tetrabutylammonium hydrogen bis-o-nitrobenzoate, tetrabutylammonium hydrogen bis-p-nitrobenzoate, ›tetrabutylammoniumhydrogenbis-N,N-dimethylaminobenzoate; tetrabutylammonium hydrogen bis-N,N-dimethylaminobenzoate, tetrabutylammonium hydrogen bis-p-methoxybenzoate and tetramethylammonium hydrogen maleate. ### Claim 10 (depends on 1) A process as claimed in claim 1, wherein the quantity of catalyst used is from 10 to 150 ppm. ### Claim 11 (depends on 1) A process as claimed in claim 1, wherein solid state polycondensation is conducted by heating at a temperature in the range of 180.degree.-220.degree. C. ### Claim 12 (depends on 1) A process as claimed in claim 1, wherein the solid state polycondensation is conducted for a period of 2 to 10 hours. ### Claim 13 (depends on 1) A process as claimed in claim 1, wherein the solid state polycondensation is conducted in a fluidized bed using an inert gas as the fluidizing gas. ### Claim 14 (depends on 1) A process as claimed in claim 1, wherein the solid state polycondensation is conducted in presence of one of nitrogen, argon, carbon dioxide, and helium as fluidizing gas.