Arco may get a special payment from a subsidiary.

Arco Chemical Co. is seeking to arrange $700 million in credit to be used to make a special payment to its parent, Atlantic Richfield Co., the companies said. At the same time, the board of the parent company approved looking into the possibility of selling 19.9% of Arco Chemical to the public. It was announced last week that management was investigating the plan. Repayment of the $700 million in credit, being arranged by Morgan Guaranty Trust Co. of New York, would become the sole responsibility of Arco Chemical, not the parent company.