Specialty chemical maker Stepan is buying Bayer’s North American unsaturated polyester business. At its facility in Columbus, Ga., Bayer makes powder resins for metal coatings and liquid resins for coatings, adhesives, and elastomers. The business has about $64 million in annual sales. Some 45 employees at the site will transfer to Stepan. Bayer acquired the plant in 2000 as part of its purchase of Sybron Chemicals. Stepan makes the unsaturated polyester precursor phthalic anhydride in Millsdale, Ill.