Process for preparing branched polycarbonate

• US 20050020804A1
• Filed: 06/29/2004
• Published: 01/27/2005
• Est. Priority Date: 07/23/2003
• Status: Active Grant

• Current Assignee: Trinseo Europe Gmbh
• Original Assignee: Dow Global Technologies, Inc. (Dow, Inc.)
• Inventors: Elbert, Bernhard, Rohde, Susanne
• Granted Patent: US 7,057,005 B2
• Time in Patent Office: Days
• US Class Current: 528/196
• CPC Class Codes: C08G 64/14 containing a chain-terminating or -crosslinking agent
• CPC Class Codes: C08G 64/20 General preparatory processes
• CPC Class Codes: C08G 64/24 and phenols

Abstract

The present invention is a process for producing branched polycarbonate providing for optimum utilization of the branching agent. It was surprisingly found that adding at least a portion of the coupling catalyst to the polymerization at a point during the oligomerization in the reaction results in a higher degree of branching and improved rheological properties.

Claims

1. A process for producing a branched polycarbonate composition from dihydric phenol, carbonate precursor, multifunctional phenolic branching agent and monophenolic chain terminator using a coupling catalyst which process comprises the sequential steps of:

a) combining a dihydric phenol, a multifunctional phenolic branching agent, base and water to form the reaction mixture,

b) then adding at least part of the carbonate precursor and the water immissible organic solvent and reacting the polymerization mixture, partially oligomerizing the dihydric phenol,

c) then adding a monophenolic chain terminator and at least a part of the coupling catalyst and base to the reaction mixture,

d) adding the balance of the carbonate precursor (if any) and continuing the reaction of the polymerization mixture,

e) adding the balance, if any, of the coupling catalyst,

f) completing the polymerization reaction.

2. A process according to claim 1 for producing a branched polycarbonate wherein all of coupling catalyst is added in step c) in the presence of the partially oligomerized dihydric phenol.

3. A process according to claim 2 for producing a branched polycarbonate wherein the coupling catalyst added in step c) is added to the oligomerizing reaction mixture at the point where the Mw is between about 1,200 and about 1,800 g/mole.

4. A process according to claim 3 for producing a branched polycarbonate wherein the coupling catalyst is added to the oligomerizing reaction mixture at the point where the Mw is between about 1,400 and about 1,600 g/mole.

5. A process according to claim 1 for producing a branched polycarbonate wherein there is a second or late addition of coupling catalyst separate from and after the addition of the first coupling catalyst added in step c) and after further reaction and polymerization of the step c) reaction mixture.

6. A process according to claim 5 for producing a branched polycarbonate wherein the first coupling catalyst added in step c) is added to the oligomerizing reaction mixture at the point where the Mw is between about 1,200 and about 1,800 g/mole.

7. A process according to claim 5 for producing a branched polycarbonate wherein a first coupling catalyst is added to the oligomerizing reaction mixture at the point where the Mw is between about 1,400 and about 1,600 g/mole,

8. A process according to claim 5 for producing a branched polycarbonate wherein the second the coupling catalyst component is added to the reaction mixture at the point where the Mw has increased to at least about 10,000.

9. A process according to claim 5 for producing a branched polycarbonate wherein the first addition of the coupling catalyst is in an amount of from 0.5 to 20 mole % of the total coupling catalyst amount that is added.