The present invention relates to the improvement of metal bond strength in polypropylene films surface treated at higher levels through the addition to the basic isotactic polypropylene (iPP) polymer of an amount of syndiotactic polypropylene (sPP) in an amount no more than about 10 percent by weight...http://www.google.es/patents/US7026055?utm_source=gb-gplus-sharePatente US7026055 - Metal bond strength in polypropylene films
