Diversified science-based group of companies - multinational - based in the United States; founded in 1902 with aim of exploiting mineral deposits for grinding-wheel abrasives; concentrated on sandpaper, inventing a water-proof sandpaper in 1920s; invented masking tape in 1925; diversified into video tape, microfilm, printing plates, post-it notes, print cartridges, pharmaceuticals and fabric cleaning products.