Process and apparatus for producing a fibre/binder board, and fibre/binder board

摘要

In fibre/binder boards produced on board machines (endless-wire machines and cylinder machines), the nonwoven plies frequently only inadequately adhere to one another. The cause is the difference in weight between light fibres and binder. The heavier binder is drawn off with the excess production water. The binder content in the boards is so low that the desired strength is not reached. According to the invention, the charge mixture is now separated at a screen drum before it is charged to the felt. A fibre layer revolves with the screen drum. It is fixed below the felt to the surface thereof, on the one hand by the pressure of the screen drum and on the other hand by a pressure which is below atmospheric pressure. A water/binder mixture flows through the screen drum and drops like rain upon the precompacted fibre layer. The latter acts as a filter and prevents entrainment of binder with production water. This gives a compact nonwoven ply of a fibre layer and a binder layer. On winding up on a winding drum, fibre layers are intimately joined to binder layers of different nonwoven plies. Ply separations and surface damage are avoided. <IMAGE>