Film lagging exposed roof in mechanised faces - using perforated or porous and gas-permeable material to allow gas or air to escape

摘要

Lagging the exposed roof with film in mechanised coal-mining operations is to hold the sensitive roof beds and prevent flaking and falls which give rise to dust and other dangers. The film is normally dispensed from a roll and bonded to the roof with the aid of an adhesive containing a solvent and backed up by a pressure roller to press it to the exposed roof surface. The film to be used now is to be perforated right the way across, or else be designed as a porous and gas-permeable material. Typically the film used are thermo plastics such as polyolefine, polyvinylchloride or polyester resin material. The aim of the perforations is to allow any air or gas bubbles forming between the film and roof to escape without rupturing the film.