Abstract: A cross-laminate web is formed of two oriented films, the films being arranged so that the main direction of orientation of the first film (A) generally follows the longitudinal direction (D) of the web and the main direction of the second film (B) is perpendicular (F) to that direction. The coefficient of elasticity of the material of the first film, in an unoriented state, is at least 115% lower than that of the material of the second film, and the heat shrinkability of the first film is greater than that of the second film. Bags formed from the cross-laminate have heat seals with improved shock peel strength.

Abstract: A laminate of thermoplastic polymeric films comprises at least one fluted ply A and at least one substantially flat ply B, adhered to one another in bonded zones along the flute crests. The wavelength of the flutes is preferably no more than 3 mm. Ply A has a generally uniform thickness or can have attenuated zones of lessor thickness extending parallel to the flute direction, each bonded zone being located mainly within an attenuated zone. The flutes can be sinuous with crests on both sides of ply A and can be adhered on each side to a ply B, in which case, attenuated zones can be on both sides and can have different widths. The flutes can be filled with filler material, including reinforcement strands, and one or both sides can be perforated. The method and apparatus employ aligned grooved fluting rollers and a grooved laminating roller.

Abstract: Processes and apparatus for extruding a tubular film of polymer material. The apparatus comprises a circular coextrusion die having an inlet (10) for the or each component and having an exit channel (18) ending in a circular exit orifice (21) which is located radially outwardly from the die axis compared to the inlet (10). The die comprises several planar or conical die parts (5, 6, 7, 28, 29) clamped together, with surfaces supplied with grooves (14) shaped to form channels (11, 12, 13) for the flow polymer material. The shape of the channels is adapted to equalize the flow over the circumference of the exit orifice (21), and the flow of material is divided between the inlet (10) and the exit (21) into a number of part flows (13) of generally helical form with space (15) provided for overflow of material between said part flows, whereby the part are adapted so that they join to one common, circular flow.

Abstract: A cross-laminate web is formed of two oriented films, the films being arranged so that the main direction of orientation of the first film (A) generally follows the longitudinal direction (D) of the web and the main direction of the second film (B) is perpendicular (F) to that direction. The coefficient of elasticity of the material of the first film, in an unoriented state, is at least 115% lower than that of the material of the second film, and the heat shrinkability of the first film is greater than that of the second film. Bags formed from the cross-laminate have heat seals with improved shock peel strength.

Abstract: A method and apparatus are described for coextruding two materials A and B, in which B is extruded on A through a port (3), in which the separating wall between the flows of A and B is formed as a flap closure (4) adapted to act as a non-return valve for the flow of B into A, and further means are provided for extruding B through the port in pulses. The pulses may be effected by opening and closing the closure, by mechanical transmission means or by the effect of imposing pressure difference on the flap (4) by the flows of A and/or B. The pulsing means preferably involves rams (1). The invention is particularly suitable for extruding a low viscosity material B onto a higher viscosity material A, or for making sheets or pipes with alternating segments of differential flexibility, or for coextruding a flow of solid particles with a flow of liquid.

Abstract: Apparatus for heat-sealing polymer films which shrink when heated include provision for moving the zone of application of heat and pressure during the heat sealing process. This allows for shrinking of the polymer film in a region adjacent to the heat seal so that the film thickens and is more resistant to failure in use through peeling. The apparatus includes a pair of sealing bars (4, 5) one of which (4) is wedge-shaped and the other of which (5) is flat. Both bars are heated and one of them can be moved in direction (12) to apply pressure to film located between the bars. At the beginning of the heat sealing step pressure is applied over an initial zone along the apex of the wedge. Subsequently the bare (4) is rolled around an axis located near to the apex of the wedge, in the direction shown by the right hand end of arrow (13), to apply heat and pressure over a wider zone located adjacent to the initial zone.

Abstract: A cross-laminate of two or more individually stretch oriented films where the directions of orientation of the films are in criss-crossing relation, has a pattern of generally parallel elongated ribs extending lengthwise of the laminate. The ribs are defined between generally transversely coincident convex and concave curved surfaces on opposite faces of the laminate, the concave surface having a radius of curvature greater than that of the convex surface so that the ribs have a thickness greater than the average thickness of the laminate. The laminate material adjacent to lateral boundaries of the ribs is in a tensionless state reversely curved relative to the rib curvature making the material between adjacent pairs of ribs generally flat. The rib pattern is preferably regular with a preferred average transverse spacing between adjacent ribs, measured peak to peak, of about 1-10 mm. The convex surfaces of the ribs can all be on the same side of the laminate or can alternate in series between opposite sides.

Abstract: In an apparatus for cutting a tubular film into an elongated strip wherein the tubular film is fed at a given velocity in flattened form from a supply reel to an expansion zone where the film is expanded into a tube, advanced after such expansion along a mandrel, cut into a flat strip while advancing along the mandrel, and the flat strip is removed from the mandrel at an angle to the mandrel axis, the mandrel is hollow and air is introduced into the hollow mandrel under sufficient pressure that the flattened film is expanded into a relatively stiff cylindrical tube that makes a sliding fit with the mandrel and resists deformation while being supported thereon, Improved positive control over the film during its expansion and advance to the mandrel is achieved by means of moving surfaces, e.g. endless belts or roller arrays, that define a diverging expansion zone and are driven at a velocity equal to the velocity at which the film is fed.

Abstract: A parachute having an orientable thermoplastic polymeric film material is provided with at least one stretched zone in which the material has been stretched in a first direction and, adjacent to the opposite sides of the zone, unstretched zones in which the material is substantially unstretched. The material is of particular value for preventing rupture of the canopy or the connecting straps.

Abstract: Flexible tubular film is helically cut into a flat strip by feeding the tubular film in flattened form from a supply source to a film feeding means advancing the flat film tube at a predetermined velocity to a tube expansion zone in which the flat tube is expanded into a generally cylindrical tube and passed axially over a hollow mandrel slightly less in external diameter than the diameter of the expanded tube to be cut helically while on the mandrel into a flat strop that is removed at an angle to the mandrel axis. The tube is expanded in the zone by inflation with air fed through the mandrel in a direction countercurrent to the direction of tube movement and under a pressure sufficient to render the expanded tube stiff as it slides over the mandrel and resistant to deformation while being helically cut.

Abstract: Orientable thermoplastic polymeric film material is provided with at least one stretched zone in which the material has been stretched in a first direction and, adjacent to the opposite sides of the zone, unstretched zones in which the material is substantially unstretched. The material is of particular value for preventing rupture of bags containing the material, especially when the zones are adjacent a seam in a filled sack and/or in the gusset of a gusset bag.

Abstract: Sheet material (4) is stretched transversely into longitudinally extending pleats by passage between intermeshing grooved rollers (A and B) having circularly or helically extending grooves in their surfaces. Each groove is formed of a base (6a,6b) and side walls (5a,5b) inclined outwardly to a peak (7a,7b). Portions of adjacent side walls (5a,5b) are parallel to one another. The peaks are less than about 3 mm apart and the film is stretched by the peaks and is compressed between the side walls by forcing the rollers together. The pleated material is generally then stretched longitudinally substantially to eliminate the pleats and it may then be again stretched transversely between a further set of intermeshing grooved rollers.

Abstract: A high-strength laminate comprising generally weakly adhered biaxially oriented films, each formed of a blend which exhibits a distinct fibrous morphology with the fibres forming a distinct unidirectional grain when measured on a macro-scale but with the fibre-portions strongly deflected from this direction as seen on a micro-scale and with the unidirectional grain in at least two of the films criss-crossing each other. Producing this laminate by melt attenuating the blend(s) while extruding the latter to films, cross-laminating the layers before or after solidification while they are still in molecularly unoriented state--except for the weak orientation produced by the melt-attenuation--and finally strongly biaxially orienting the laminate by stretching in several steps, whereby the stretching is generally uniaxial during each step.

Abstract: A high strength laminate formed by stretching together is superposed relation at least two laminates of at least two films each, which films exhibit a distinct fibrous morphology with the fibres forming a distinct generally unidirectional grain when observed on a macroscale but with the fibre-portions strongly deflected from this direction when observed on a microscale and with said unidirectional grain in at least two of the films criss-crossing each other, so as to combine such laminates which are then separated by peeling apart. The resultant separated laminates have high strength with one highly smooth surface evidenced by high gloss and a high coefficient of friction particularly suitable for the production of high quality sacks while the opposite surface is slightly corrugated in its lengthwise direction.

Abstract: A sandwich of plural films of thermoplastic orientable polymers wherein the adjacent surfaces of each adjacent film pair are in direct face-to-face contact while being positively advanced is positively deflected into a temporarily generally uiniform zig-zag or pleated configuration, the deflecting forces being sufficiently strong that the films in the sandwich are cold welded together while being laterally stretched. The deflection into the temporarily pleated configuration can be repeated.

Abstract: Method and apparatus for the manufacture and stretching of a laminate comprising forming at least two laminates, which are stretched together in superposed relation, from at least four films so as to form a combination of laminates and subsequently peeling said combination to form separate laminates. A laminate prepared in this manner is advantageous in that one of its surfaces has a high smoothness evidenced by high gloss and a high coefficient of friction which makes the laminate particularly suitable for use in the production of high quality sacks.

Abstract: A two-dimensional integral net having a nap in form of relatively long fibres which are integral with the net and protrude from the edges which surround the apertures of the net.A method of producing this net from a film is by heating selected areas of the film to a molten state and dragging out this molten material into fibres to leave apertures in the film while controlling the fibre-dragging by cooling with an air jet.

Abstract: A method of preparing a high strength sheet material comprising (a) forming a laminate comprising at least two layers of a thermoplastic polymer material, each layer having a fibrillar grain structure providing a predominant direction of splittability in each said layer, and wherein the layers are bonded to one another with the said predominant directions of splittability generally transverse to each other, (b) biaxially orienting the molecules of said layers by stretching the layers in substantially uniaxial steps, at least the transverse stretching step thereof being effected by applying pressure to the surface of the laminate along lines extending substantially in the longitudinal direction of the laminate to impart thereto a transversely waved or sinuous configuration, and (c) subjecting the biaxially oriented laminate while in the sinuous condition to a heat treatment while allowing at least 7% shrinkage of the laminate to take place in at least its transverse direction.

Abstract: A coextrusion die for the extrusion of plastics materials in the shape of a tubular film comprising supply means for separately supplying at least two plastics materials to said die, a distribution channel system connected to each supply means, each distribution channel system comprising at least two arched channels provided in different axial planes, the ends of each arched channel being connected to the middle portion of the following arched channel and the distribution channel systems being located at different distances from the center axis of the die, collecting chambers communicating with said distribution channel systems and an annular extrusion slot communicating with the collecting chambers.

Abstract: An integrated reticulate structure comprising interconnected criss-crossing arrays of continuous or discontinuous filaments. The arrays are located in different layers and are mutually connected by flexible, generally strip-shaped links. Each link is integral with a filament in one array and with a filament in another array.A method of manufacturing an integrated reticulate structure commencing by extruding a sheet in form of an adhesively connected assembly of one or more films and one or more arrays of ribs extending from at least one surface of each such film. To enable a formation of thin ribs and of a close spacing of the ribs there is preferably further coextruded a separating component between the ribs.