3M Co. (NYSE:MMM) said today that it paid $1 billion for the Polypore’s (NYSE:PPO) separations media business, which makes membranes and modules for blood treatment, ultrafiltration and gas transfer. St. Paul, Minn.-based 3M said Polypore’s separation media segment puts up annual sales of roughly $210 million. The acquisition is expected to dilute earnings this year by […]