BARBERTON, Ohio (July 12)— RBX Corp. of Roanoke, Va. said it is seeking court approval to close its Midwest Rubber Custom Mixing company. The closing, which will leave 100 workers out of work, is due to excess capacity in the custom mixing industry combined with slowing demand from the automotive industry, a company release stated. Closed-cell foam producer RBX Corp. which is currently under Chapter 11 bankruptcy protection, filed a motion to close the Barberton plant last month in the U.S. bankruptcy court in Virginia. The Barberton facility mixes and compounds rubber for the automotive and other industries. RBX Corp. said it hopes to move business from Barberton to its Tallapoosa, Ga. site or to one of its seven other production locations in the U.S.