Abstract: Thermoplastic articles such as fenders, of large cross-sectional dimensions, may be made by extrusion without shrinkage voids by extruding a first stream of theremoplastic as a hollow profile, and extruding a second stream of molten thermoplastic by a second extruder and forcing same under pressure into the hollow profile to till the voids of shrink-age on cooling.

Abstract: The invention provides a method of forming composite products of two incompatible plastics or other materials by extruding a first stream of plastic through a die to form a profile and coextruding another stream on the surface thereof which is fusible with the first plastic and is impregnated with foreign matter and causing, by means of high heat, pressure drop or shear stress, a rupture of the layer to form a pattern of irregular cavities and projections to which a coating can be applied which will invade the cavities and surround the projections to bond with the extruded profile.

Abstract: A pipe joint seal comprises an insert (10) adapted to be mounted around the joint and the pipe sections adjacent thereto and having in its inner side dovetailed grooves (11) or the like which are filled with a plastic sealing compound. The insert (10) can be clamped around the pipes and the joint by means of a sheet-metal union piece (21) having bent edges (22) to form a channel within which said insert (10) is mounted. When insert (10) is tightened around the pipes, the sealing compound urges the insert portions defining the dovetailed grooves (11) tightly against the pipes so that a satisfactory seal is obtained also on uneven pipe surfaces. By designing one bent longitudinal edge (22) of the union piece (21) with a height greater than that of said insert, and by causing said bent edge to engage with a groove in one of said pipes, the seal can be simply and conveniently held in nondisplaceable engagement with said pipe, while the other pipe is displaceable in the seal.

Abstract: This invention discloses a plastic film having a non-slip surface comprising spaced random patterns of rigid peaks and ridges formed by a second thermo-plastic layer coextruded with and bonded to the plastic film and rupturing the second layer during expansion.

Abstract: The present invention discloses an improved heat shrinkable sleeve and method for making same in which an extruded sleeve piece is heated above the cross-linking temperature of the plastics material by immersing it in a heated bath while supporting its shape by fixed tubes and then expanding the sleeve piece while it is simultaneously cooled by means of a pair of rotating rolls which are movable away from each other.

Abstract: The method maintains a set nip clearance at a uniform value across the widths of the calendar, at different calendar loads, in at least the last nip, in the working direction, of a calender stack or the like including at least three rolls subjected to a common work-press load, with at least one roll being crowned to correspond to the maximum load of the calendar and at least one roll being adjustable. The thickness of the material being treated is sensed at one or several points in a direction transverse to the material web, or the deflection, or the load, is sensed at one or several of the rolls. The position of one or more adjustable rolls is displaced, relative to the common plane through the roll axes, in accordance with the sensing in a manner such that the axis of the adjustable roll or rolls remains parallel to the adjacent roll axis. The adjustable rolls may be displaced horizontally either linearly or arcuately to follow the contour of the adjacent rolls.

Abstract: A method of making a non-slip plastic film comprises extruding separate plasticized plastic materials in two streams so that one stream abuts against and adheres to the other to form a combined plastic layer. The combined plastic layer is then stretched by directing air centrally into a tubular formation of this layer. One of the plastic materials comprises a material having an expanding agent or a foaming agent and the stretching causes the breaking of the voids of the foam plastic to form a rough, irregular net-like formation on the exterior of the other plastic. The apparatus includes two separate nozzles arranged to extrude plastic material so as to intersect and form a combined plastic.