Processes for producing polycarbonate and molded polycarbonate articles
View Patent ↗A subject for the invention relates to processes for producing a polycarbonate containing a plant-derived starting material and to molded articles thereof, the polycarbonate having excellent mechanical strength, heat resistance, a low refractive index, a large Abbe number, low birefringence, and excellent transparency. The invention relates to a process for producing a polycarbonate which includes a step in which one or more dihydroxy compounds including a dihydroxy compound having at least one linking group —CH 2 —O— in the molecule thereof are reacted with a carbonic acid diester in the presence of a polymerization catalyst, wherein the dihydroxy compound having at least one linking group —CH 2 —O— in the molecule thereof has a formic acid content lower than 20 ppm. The invention further relates to a molded article constituted of a polycarbonate or a composition of the polycarbonate, the polycarbonate being a polycarbonate which contains constituent units derived from a dihydroxy compound having at least one linking group —CH 2 —O— in the molecule thereof and has an Abbe number of 50 or larger and a 5% weight loss temperature of 340° C. or higher.
1. A process for producing a polycarbonate, the process comprising reacting one or more dihydroxy compounds comprising a dihydroxy compound having at least one linking —CH 2 —O— group with a carbonic acid diester in the presence of a polymerization catalyst, to form a polycarbonate,
wherein:
the polymerization catalyst comprises at least one metal compound selected from the group consisting of an alkali metal compound and an alkaline earth metal compound;
an amount of an alkali and/or alkaline earth metal compound contained in the one or more dihydroxy compounds is 5 μmol or smaller, in terms of an amount of metal(s) contained per mole of the one or more dihydroxy compounds reacted as starting material; and
the dihydroxy compound having at least one linking —CH 2 —O— group has a formic acid content of 3 ppm or lower than 20 ppm.
2. The process according to claim 1 , wherein an addition amount of the at least one metal compound of the polymerization catalyst ranges from 0.1 μmol to 25 μmol in terms of the amount of metal(s) added per mole of the one or more dihydroxy compounds reacted.
3. The process according to claim 1 , wherein the one or more dihydroxy compounds further comprise at least one other dihydroxy compound selected from the group consisting of an alicyclic dihydroxy compound, an aliphatic dihydroxy compound, an oxyalkylene glycol, an aromatic dihydroxy compound, and a diol having a cyclic ether structure.
4. The process according to claim 1 , wherein the dihydroxy compound having at least one linking —CH 2 —O— group is a dihydroxy compound represented by formula (1):
5. The process according to claim 4 , wherein the dihydroxy compound represented by formula (1) has been stored under at least one condition selected from the group consisting of an inert gas atmosphere, a reduced-pressure atmosphere, in the presence of a free-oxygen absorber, in the presence of a desiccant, and at a temperature of 40° C. or lower.
6. The process according to claim 4 , wherein the dihydroxy compound represented by formula (1) is reacted in a liquid state with the carbonic acid diester.
7. The process according to claim 4 , wherein a proportion of the dihydroxy compound represented by formula (1) relative to the one or more dihydroxy compounds is 10% by mole or higher.
8. The process according to claim 4 , wherein the one or more dihydroxy compounds further comprise at least one other dihydroxy compound selected from the group consisting of an alicyclic dihydroxy compound, an aliphatic dihydroxy compound, an oxyalkylene glycol, an aromatic dihydroxy compound, and a diol having a cyclic ether structure.
9. The process according to claim 4 , wherein an addition amount of the at least one metal compound of the polymerization catalyst ranges from 0.1 μmol to 25 μmol in terms of the amount of metal or metals added per mole of the one or more dihydroxy compounds reacted.
10. The process according to claim 9 , wherein the dihydroxy compound represented by formula (1) has been stored under at least one condition selected from the group consisting of an inert gas atmosphere, a reduced-pressure atmosphere, in the presence of a free-oxygen absorber, in the presence of a desiccant, and at a temperature of 40° C. or lower.
11. The process according to claim 9 , wherein a proportion of the dihydroxy compound represented by formula (1) relative to the one or more dihydroxy compounds is 10% by mole or higher.