High strength low cost impervious structural wooden sheet - has alternating layers of wood and asphalt or bitumen binder, prepn. hot pressed with edges covered to prevent escape of binder

摘要

Timber structural sheet consists of thin layers of wood bonded together over their surface. These layers alternate with layers of asphalt or bitumen in the stack and these last layers are bonded to the wood layers over their whole area. The structure preferably has an extra outer layer of "Resopal" (R.T.N.). In the prodn. of the laminate the asphalt or bitumen layers are applied hot and the adjacent layers of wood are added. The complete stack is hot pressed to produce a good bond between wood and asphalt etc. Moreover the ends of the stack are closed off in the press so that no asphalt/bitumen can escape. The material can, if desired, be heated e.g. by induction while it is pressed. The sheet can be cut to size after pressing or the layers themselves are cut beforehand. ADVANTAGE - The laminated prod. is cheap, has a high mechanical strength, prevents the movement of moisture through its thickness, and retains its thermal insulating properties when warm or cold.