Process for preparing poly(ester-carbonate)s and poly(ester-carbonate)s prepared thereby
View Patent ↗A method of preparing a poly(ester-carbonate) includes contacting an aqueous solution including a dicarboxylic acid with a first solution including phosgene and a first organic solvent in a tubular reactor to provide a first reaction mixture. A dihydroxy aromatic compound, the corresponding dialkali metal salt of the dihydroxy aromatic compound, or a combination comprising at least one of the foregoing, water, and a second organic solvent are combined to provide a second reaction mixture. The method further includes introducing the first reaction mixture, the second reaction mixture, and a second solution comprising phosgene to a tank reactor, wherein the tank reactor has a first pH of 7 to 10. The pH is optionally raised to 9 to 11 to provide a third reaction mixture including the poly(ester-carbonate). Poly(ester-carbonate)s prepared according to the method described herein are also disclosed.
1. A method of preparing a poly(ester-carbonate), the
method comprising
contacting an aqueous solution comprising a dicarboxylic acid with a first solution comprising phosgene and a first organic solvent in a tubular reactor to provide a first reaction mixture comprising the dicarboxylic acid, the corresponding diacid chloride, phosgene, or a combination comprising at least one of the foregoing;
combining a dihydroxy aromatic compound, the corresponding dialkali metal salt of the dihydroxy aromatic compound, or a combination comprising at least one of the foregoing, water, and a second organic solvent to provide a second reaction mixture;
introducing the first reaction mixture, the second reaction mixture, and a second solution comprising phosgene to a tank reactor, wherein the tank reactor has a first pH of 7 to 9; and
subsequently raising the pH to 9 to 11 to provide a third reaction mixture comprising the poly(ester-carbonate).
2. A method of preparing a poly(ester-carbonate), the method comprising
contacting an aqueous solution comprising a dicarboxylic acid with a first solution comprising phosgene and a first organic solvent in a tubular reactor to provide a first reaction mixture comprising the dicarboxylic acid, the corresponding diacid chloride, phosgene, or a combination comprising at least one of the foregoing;
combining a dihydroxy aromatic compound, the corresponding dialkali metal salt of the dihydroxy aromatic compound, or a combination comprising at least one of the foregoing, water, and a second organic solvent to provide a second reaction mixture;
introducing the first reaction mixture, the second reaction mixture, and a second solution comprising phosgene to a tank reactor, wherein the tank reactor has a first pH of 7 to 9, to provide a third reaction mixture comprising the poly(ester-carbonate).
3. The method of claim 1 , wherein the tubular reactor comprises a tube jacket arranged outside the tubular reactor, the jacket comprising water at a temperature of 1 to 10° C. flowing through the jacket to maintain a reaction mixture temperature of 20 to 55° C. within the tubular reactor.
4. The method of claim 1 , wherein the first reaction mixture has a residence time in the tubular reactor of 15 to 50 seconds.
5. The method of claim 1 wherein the contacting comprises introducing the first solution comprising phosgene and a first organic solvent to the tubular reactor at a linear fluid velocity of 3 to 45 meters per minute.
6. The method of claim 1 , wherein the contacting comprises introducing the aqueous solution to the tubular reactor at a rate that provides a combined linear velocity of all fluids in the tubular reactor of 5 to 65 meters per minute.
7. The method of claim 1 , wherein the aqueous solution comprises an alkaline aqueous solution comprising 20 to 40 wt. % of an alkali metal hydroxide.
8. The method of claim 1 , wherein the aqueous solution further comprises a catalyst comprising a tertiary amine.
9. The method of claim 1 , wherein the second reaction mixture further comprises
a phase transfer catalyst; and
a chelant.
10. The method of claim 1 , wherein the second solution comprising phosgene is introduced to the tank reactor at a rate effective to provide a weight ratio of the phosgene to the aromatic dihydroxy compound, averaged over one hour, of 0.3 to 3.1.
11. The method of claim 1 , wherein the third reaction mixture comprises less than or equal to 125 ppm of residual dicarboxylic acid.
12. The method of claim 1 , wherein
the dicarboxylic acid comprises a C 6-36 aliphatic diacid; and
the dihydroxy aromatic compound is of the formula
HO—Z—OH
wherein Z is an aromatic C 6-24 monocyclic or polycyclic moiety optionally substituted with 1 to 6 C 1-8 alkyl groups, 1 to 8 halogen atoms, or a combination comprising at least one of the foregoing.
13. The method of claim 1 further comprising adding an end-capping agent to the tank reactor.
14. The method of claim 1 , wherein the organic solvent comprises a C 1-6 chlorinated hydrocarbon.
15. The method of claim 1 , wherein the tank reactor is a stirred tank reactor.
16. A poly(ester-carbonate) prepared by the method of claim 1 , wherein the poly(ester-carbonate) has a molecular weight drop of less than 10 and wherein the poly(ester-carbonate) comprises less than or equal to 125 ppm of residual dicarboxylic acid.
17. The poly(ester-carbonate) of claim 16 , wherein the poly(ester-carbonate) is substantially free of dicarboxylic acid-dicarboxylic acid linkages.
18. An article formed from the poly(ester-carbonate) of claim 16 .