Abstract: This invention concerns an improved apparatus for extruding abrasive pastes, especially those which contain ground glass together with polymerizable material, and which comprises a conventional piston and cylinder extrusion apparatus in which the working surfaces are protected by a replaceable lining system consisting of a thin tubular liner and two discs substantially closing its ends and enclosing the paste to be extruded. In the preferred embodiment (FIG. 1) the lining system is made of polypropylene.

Abstract: The invention relates to apparatus and a method for producing a coated film in which a cooled polymeric tubular extrudate is coated, reheated and inflated to yield an oriented, coated tubular film. The apparatus includes a coating head comprising a rotatable assembly including a support member [13] providing an orifice [14] through which the tubular extrudate may be fed, a plurality of spreading members [19] spaced-apart around the orifice, mounting means [15] for each of the spreading members operatively associated with the support member and displaceable relative thereto, and means [21] for biasing each of the spreading members into engagement with the tubular extrudate. Liquid coating medium is suitably deposited on the extrudate from a spray assembly, and the coating asembly is rotated around the extrudate thereby spreading and polishing the deposited medium to yield a uniformly coated film.