The swap will reduce the company's indebtedness by $175 million and annual interest expenses by $19.3 million, the company said.
The voluntary filing was submitted to the U.S. Bankruptcy Court in Wilmington, Del.
In a statement, President and Chief Executive Officer Michael Hoffman said Constar intended "to continue to operate as usual during the restructuring process with minimal disruption to the business."
"We intend to pay all our obligations in full," he said.
The company has been struggling to recoup losses incurred in 2002 when it was spun off from Crown Holdings Inc., the Philadelphia Inquirer reported.
Share values will be wiped out, but not from a great height. Share values closed at 4 cents Tuesday after closing at 15 cents Monday, the newspaper said.