Polymer film, film roll and knurling roller

摘要

The invention provides a polymer membrane, a membrane roller and a knurling endowing roller. A membrane producing device produces band-shaped polymer membrane. The knurling endowing device disposed at the downstream of the membrane producing device endows the knurling to the side part of the polymer membrane, i.e. an edge. The polymer membrane which is endowed with the knurling is reeled to a core, forming the membrane roller. The knurling is provided with a boss projecting from the surface of the polymer membrane. The boss is provided with a plurality of ridges and summits. The summit is formed by the intersection of ridges. The knurling is disposed at the edge in order that the length total of ridges per unit area is above a predetermined value.