in U.S. Pat. No. 4,510,301. In such a stretching operation, the film may be stretched uniaxially in either the direction coincident with the direction of movement of the film being withdrawn from the casting roller, also referred to in the art as the xe2x80x9cmachine directionxe2x80x9d, or in as direction which is perpendicular to the machine direction, and referred to in the art as the xe2x80x9ctransverse directionxe2x80x9d, or biaxially in both the machine direction and the transverse direction. The multilayered film of the invention are particularly useful for forming thermoformed three dimensionally shaped articles such as blister packaging for pharmaceuticals. This may be done by forming the film around a suitable mold and heating in a method well known in the art.
We have unexpectedly found that the fluoropolymer filmsmember which is capable of moving to and fro in the longitudinal direction of the guide duct and has a head which can be brought to rest on the fastening element is characterized in that the loading member has a duct with an inlet and an outlet, the outlet being formed at the head. In the guide duct there opens a gas supply duct which is closed by the loading member in a first position of the loading member and can be connected to the inlet in a second position of the loading member. The loading member adopts the second position during the welding process, so a gas can pass via the gas supply duct and through the loading member to the weld stud which has a through-duct.