Recent independent tests reportedly confirm that anhydrous calcium sulfate (gypsum) is an economical TiO2 extender that maintains good pigmenting performance in PP. Grade CAS-20-4 from U.S. Gypsum Co.'s Specialty Products Div., Chicago, has been used by makers of color concentrates to reduce manufacturing costs without sacrificing quality. Conducted by specialty minerals producer and distributor Kish Co. Inc. of Mentor, Ohio, the tests demonstrated that L,a,b and opacity values were essentially unchanged at TiO2 substitution levels between 10% and 25%. CAS-20-4 is an extremely white, fine-particle filler made from high-purity gypsum rock. "Its brightness, narrow particle-size distribution, and non-abrasive properties make it an ideal TiO2 extender," says Susan Dichter, business manager for USG's Specialty Products Div.
United States Gypsum Co.
125 S. Franklin Street Chicago, IL 60606-4378
Phone (312) 606-5582 Fax (312) 606-4519