# US 5,703,196 A · Process for producing polycarbonate having terminal hydroxyl groups > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,703,196 A - Document ID: US5703196A - Status: Granted - Kind: A - Application number: 08/718,514 - Filed: 1996-10-08 - Granted: 1997-12-30 - Earliest claimed: 1994-04-08 - Assignees: Asahi Kasei Kogyo Kabushiki Kaisha - Inventors: Shinji Funakoshi; Kenzou Kawai - Web page: https://patentgrep.com/patent/US5703196A ## CPC - C08G 64/305: {and alcohols} - C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS ## Abstract A process for producing a polycarbonate having terminal hydroxyl groups obtained by reacting an aliphatic polyol with a carbonate monomer, characterized by comprising the first step of producing a low molecular weight polycarbonate while removing the alcohols produced as by-products from the reaction mixture containing the aliphatic polyol and the carbonate monomer and the second step of adding to the reaction mixture the carbonate monomer in portions or continuously under the conditions that the concentration of the aliphatic polyol in the reaction mixture in the first step is 5% by weight or less and effecting the reaction while removing the alcohols produced as by-products, whereby connecting the low molecular weight polycarbonates to one another through the carbonate monomer to heighten the molecular weight. ## Claims ### Claim 1 A process for producing a polycarbonate having terminal hydroxyl groups obtained by reacting an aliphatic polyol with a carbonate monomer selected from the group consisting of a dialkyl carbonate, a diaryl carbonate and an alkylene carbonate, which comprises a first step of producing a low molecular weight polycarbonate while removing alcohols produced as by-products from the reaction mixture containing said aliphatic polyol and said carbonate monomer and a second step of adding to the reaction mixture in the first step said carbonate monomer in portions or continuously under the conditions that the concentration of the aliphatic polyol in the reaction mixture in the first step is 5% by weight or less and subjecting the resulting mixture to reaction while removing the alcohols produced as by-products to connect the low molecular weight polycarbonates to one another through the carbonate monomer, thereby increasing the molecular weight. ### Claim 2 (depends on 1) The production process according to claim 1, wherein the concentration of the aliphatic polyol in the reaction mixture in the first step is adjusted to 1% by weight or less and the second step is carried out. ### Claim 3 (depends on 1) The production process according to claim 1, wherein the aliphatic polyol and the carbonate monomer are mixed in such a proportion that the mole ratio of the former to the latter becomes 1:10 to 10:1 and the first step is carried out. ### Claim 4 (depends on 1) The production process according to claim 1, wherein the aliphatic polyol and the carbonate monomer are mixed in such a proportion that the mole ratio of the former to the latter becomes 1:2 to 2:1 and the first step is carried out. ### Claim 5 (depends on 1) The production process according to claim 1, wherein the first step is carried out at a temperature of 80.degree. to 200.degree. C. at a pressure of 6.7.times.10.sup.2 Pa (5 mmHg) to atmospheric pressure and the second step is carried out at a temperature of 100.degree. to 200.degree. C. at a pressure of 13 Pa to 2.7.times.10.sup.4 Pa (0.1 to 200 mmHg). ### Claim 6 (depends on 1) The production process according to claim 1, wherein the first step is carried out at a temperature of 80.degree. to 200.degree. C. at a pressure of 6.7.times.10.sup.2 Pa (5 mmHg) to atmospheric pressure and the second step is carried out at a temperature of 100.degree. to 200.degree. C. at a pressure of 13 Pa to 2.7.times.10.sup.3 Pa (0.1 to 20 mmHg). ### Claim 7 (depends on 1) The production process according to claim 1, wherein the dialkyl carbonate is a dialkyl carbonate having 1 to 12 carbon atoms. ### Claim 8 (depends on 1) The production process according to claim 1, wherein the diaryl carbonate is a diaryl carbonate having 6 to 20 carbon atoms. ### Claim 9 (depends on 1) The production process according to claim 1, wherein the alkylene carbonate is an alkylene carbonates comprising a 5-membered to 7-membered ring. ### Claim 10 (depends on 1) The production process according to claim 1, wherein the aliphatic polyol is an aliphatic diol. ### Claim 11 (depends on 10) The production process according to claim 10, wherein the aliphatic diol consists of an alkylene glycol or a polyoxyalkylene glycol. ### Claim 12 (depends on 11) The production process according to claim 11, wherein the alkylene glycol has 3 to 20 carbon atoms in its main chain or the polyoxyalkylene glycol has 2 to 12 carbon atoms between oxygen atoms. ### Claim 13 (depends on 1) The production process according to claim 1, wherein the molecular chain length of the low molecular weight polycarbonate obtained in the first step is 2 to 10 units. ### Claim 14 (depends on 1) The production process according to claim 1, wherein the molecular weight of the polycarbonate having terminal hydroxyl groups obtained in the second step is 500 to 8,000. ### Claim 15 (depends on 1) The production process according to claim 1, wherein the concentration of the aliphatic polyol in the reaction mixture is adjusted to 5% by weight or less by removing the aliphatic polyol from the reaction mixture. ### Claim 16 (depends on 15) The production process according to claim 15, wherein the concentration of the aliphatic polyol in the reaction mixture is adjusted to 5% by weight or less by lowering the pressure to a reduced pressure of 13 Pa to 2.7.times.10.sup.3 Pa (0.1 to 20 mmHg). ### Claim 17 (depends on 15) The production process according to claim 15, wherein the concentration of the aliphatic polyol in the reaction mixture is adjusted to 5% by weight or less by elevating the temperature to 100.degree. to 200.degree. C. ### Claim 18 (depends on 15) The production process according to claim 15, wherein the concentration of the aliphatic polyol in the reaction mixture is adjusted to 5% by weight or less by blowing an inert gas into the reaction mixture.