July 10 - Fitch Ratings has assigned a 'BBB-' rating to Westlake Chemical Corporation's (Westlake; NYSE: WLK) proposed $250 million 10-year notes. The Rating Outlook is Stable. A complete list of ratings follows at the end of this press release. The notes will be senior unsecured obligations of Westlake, guaranteed by material subsidiaries and will rank equally with the company's other senior unsecured debt, totaling $754 million as of March 31, 2012. The company had a total of $765 million