The chloroprene rubber (CR) business of Denka Co. Ltd. (TYO:4061) has increased its revenue since Nov. 1 of last year, when operations started up at U.S. subsidiary Denka Performance Elastomer LLC. Domestically, however, the business has stagnated somewhat, with a decline in CR for vehicle parts due to a downturn in automotive production volume. Denka has also suffered declines in…