IMPROVED PINNED ROLLERS AND PROCESSES FOR MANUFACTURING FIBRILLATED FILMS
Roller (10) has a cylindrical surface (12) from which project pins (16) inclined at an angle (A) between 20 and 80 to the tangent to the roller. The pins have a projection length of 0.5 to 2.0 mm and a diameter of 0.2 to 0.8 mm. They are arranged in double rows (14) with 25 to 34 pins to the inch arranged in a spaced staggered relationship in two adjacent lines. Each row is either inclined to a line parallel to the axis of the roller or of sinusoidal form. A film to be fibrillated is advanced over the surface of the rotating roller for an arc length of contact of 30 to 37 with the ratio of the surface speed of the roller to that of the advancing film being between 1.8 to 1 and 2.2 to 1.