A STRUCTURAL PLY OF A PAPERBOARD CORE, A PAPERBOARD CORE MADE THEREOF, AND A METHOD OF IMPROVING THE STIFFNESS OF A PAPERBOARD CORE

摘要

The present invention relates to a structural ply of a spiral paperboard ply, the cross machine direction (CD) elasticity modulus E of the structural ply being substantially higher than 4500 MPa. Further, the machine direction (MD) elasticity modulus E of the structural ply is substantially higher than 7500 MPa (N/mm<2>). The invention also relates to a spiral core comprising such a structural ply. The present invention further relates to a method of improving the stiffness of a spiral paperboard core. Paperboard cores in accordance with the invention may be manufactured by using, either solely or partly, structural plies according to the invention, the paperboard for making up such structural plies having been manufactured, e.g., with a method called press drying. Paperboard based on the press drying method can be manufactured, e.g., with a board machine employing a so-called Condebelt process. The invention also relates to use of such cores as yarn carriers and as tubes for thin films and foils.