Eastman Chemical will sell its tire additives business to the private equity firm One Rock Capital Partners for $800 million. The sale includes Crystex insoluble sulfur, Santoflex antidegradants, and other products. The business employs over 500 people at seven plants and two technology centers. Eastman says the sale is part of an effort to improve the performance of its additives and functional product unit. One Rock owns the chemical maker Innophos and recently acquired BASF’s vitamin E business.