Layer-to-layer slippage within paper rolls during winding

Abstract

Crepe wrinkles are created during reeling and winding of paper rolls against a rolling drum. These defects are associated with interlayer movement of paper within the body of the roll. To study this movement, rolls made from five different papers were loaded against a rotating drum under controlled conditions and the layer-to-layer movement quantified by means of "J''-lines marked on their face. The interlayer movement of paper is directly related to frictional stress; the coefficient of friction multiplied by the radial compressive stress in the paper roll, and the shear stress created by rolling friction of the paper roll.

The amount of interlayer movement can be reduced by lowering the nip load, increasing the drum diameter, or covering the drum with a soft material. Interlayer movement increases sharply when the coefficient of friction falls below a critical value, which explains why crepe wrinkles can appear after a seemingly imperceptible change in coefficient of friction.