Fibrous sheets or films of resin-impregnated - fibrous material which are suitable for

摘要

Film or sheet consists of resin-impregnated fibrous material with regularly oriented threads aligned in the direction of the length of the film. One group of the fibres is separated from a neighbouring group by the regularly oriented threads. The threads which are parallel to the fibres consists of a material which exhibits a different permeability to X-rays as compared with the fibres.