Houston-based investment firm Main Street Capital Corp. said Tuesday it led a $12 million financing round for Baton Rouge’s East West Copolymer & Rubber LLC.

East West, which bought the synthetic rubbers plant from Lion Copolymer in April, will use the money for working capital and expansion.

Main Street provided $9.6 million of the total.

East West’s products are used in making automobile, industrial and agriculture tires.

Main Street provides long-term debt and equity capital to companies whose annual revenue generally ranges from $10 million and $150 million.