| 摘要 |
The flat tubular film (1) of a thermoplastic material has inner surfaces which are not welded or adhesive bonded together but are in contact with each other at local points. The contact points form inner cells (3), hermetically sealed, containing a gas mainly of air. The air-filled cells are distributed in a regular pattern between the two inner surfaces of the tubular film, where each plane at right angles to the longitudinal axis is at least at a gas cell. The cells are essentially square, where the diagonal axis is parallel to the longitudinal axis of the tubular film, and the length of the sides is greater than the gap between neighboring cells. An Independent claim is included for a manufacturing process where the film material is extruded, and a gas is fed between the inner surfaces under pressure. The gas-filled tube is passed between two cylinders (2,2') without welding or adhesive bonding the layers. At least one cylinder (2) has a surface structure where its relief pattern applies pressure only at local points to develop an internal cell formation and trap the air within the cells in a hermetic seal. Preferred Features: After the formation of the internal cell structure, the two walls of the flat film are welded together to form a pocket. |
