Arxada is buying the antimicrobial chemical maker Troy. The centerpiece of the deal is Troy’s 3-iodo propynyl butyl carbamate (IPBC), a potent antifungal compound used in coatings, wood protection, home and personal care products, plastics, textiles, energy, and metalworking fluids. Troy also sells other surface-finishing and preservative chemicals. The deal includes plants in the US, Germany, Thailand, and the Netherlands. Arxada is Lonza’s former specialty chemical business, which the private equity firms Bain Capital and Cinven acquired in July.