Rigid PVC extrusion

Brighton, 20th-22nd April 1999, p.388-97 PERFORMANCE OF POLYMERIC CARRIER BASED COLOURANT SYSTEMS IN RIGID PVC EXTRUSION Smith N Matthey J... 

Uses Internal lubricant for rigid PVC extrusion, inj. molding, calenders, clear blow-molded bottles, sheet food-contact coatings, paper, cellophane, polymers... 

Uses Filler, mar resist, aid, gloss aid for paints containing soivs., povird. coatings filler for plastics (rigid PVC extrusion, rigid PVC foam extrusion, plasticized PVC, cables, calendered sheet, profiles, moldings, PE/ XPE), rubber, plastics... 

Since most rigid PVC extrusion is from powder blends, and the extrusion process—especially twin-screw—is sensitive to powder blend properties of flow, compact density, and bulk density, the need to be aware of bulk density variations is most important. This awareness is especially necessary with the supplier s requirement to reduce the residual VCM content of PVC resin, which in turn can mean more severe drying cycles after a steam-stripping operation in the process. Consequently, the bulk density of PVC resin, and its particle size distribution, may be somewhat different now than previously—and the resin particle surface may be a little harder, or less absorptive to liquid additives. Many resins are much drier than before. In short, the dry-blend, powder flow, and bulk density differences of current PVC resins may require subtle changes in mixing procedures and extrusion conditions to maintain product quality (more on this later). Knowing this before the resin is blended and extruded can minimize a host of production problems. 

Uses Processing aid, surfactant, lubricant for ABS, rigid PVC extrusions, PS, color cones., and filled PP Features EBS replacement... 

Fig. 9.20 Cross sections obtained from cooling experiments of a 2.5-in-diameter 26.5 length-to-diameter ratio screw extruder. Material rigid PVC. Operating conditions are listed in the figure Tb is the barrel temperature, N the screw speed, P the pressure at the die, and G the mass flow rate. Numbers denote turns from the beginning (hopper side) of the screw. The screw was of a metering type with a 12.5 turn feed section 0.37 in deep, a 9.5 turn transition section, and a 4.5 turn metering section 0.127 in deep. [Reprinted by permission from Z. Tadmor and I. Klein, Engineering Principles of Plasticaling Extrusion, Van Nostrand Reinhold, New York, 1970. The experiments were carried out at the Western Electric Engineering Research Center, Princeton, NJ.]...

Tubes and blown Aims can be produced as multilayer structures by employing multiple extruders and coextrusion manifolds and dies. Figure 12.44 is a schematic representative of a conventional and new spiral coextrusion die. The designs can be used for both blown-film and blown-molding parison dies. In the extrusion of tubes, such as rigid PVC or PE pipe, the extrudate passes over a water-cooled mandrel and enters a cold-water bath whose length depends on the tube thickness the tube leaves the bath well below its Tm (if it is crystalline) or Tg (if it is amorphous) and is sectioned to the desired lengths. 

Calendering is much more capital intensive than the extrusion process, but higher production rates and more accurate product thickness are obtained. Mini calenders or Calandrette lines (from Battenfeld) are available for the production of rigid and semi-rigid PVC films with lower investment costs. 

EFFECTS OF REPEATED EXTRUSION ON THE PROPERTIES AND DURABILITY OF RIGID PVC SCRAP... 

Ontario, 12th-14th Oct.1999, p.48-51 NEW LOW PLATE OUT RIGID PVC LUBRICANT SYSTEM TO MEET THE PROCESSING CHALLENGES OF TODAY S HIGH-OUTPUT EXTRUSION PROCESS Decker R W Falter J A Henkel Corp. 

Journal of Vinyl and Additive Technology 3, No.3, Sept. 1997, p.210-5 EFFECT OF EXTRUSION CONDITIONS ON RIGID PVC FOAM... 

Results are presented of an investigation of the effect of extrusion conditions, such as melt temp., screw speed and draw-down, on process morphology of rigid PVC foams and the properties of the extruded profile, including density, cell structure and surface appearance. The optimum conditions for the best quality profile found in this study were 190 to 196C melt temp, and no greater than 20 rpm screw speed on a 63.5 mm single screw. 15 refs. 

RECYCLING OF PVC SUPERMARKET TRAYS INTO RIGID FOAM EXTRUSIONS... 

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