Cable insulation extrusion

P Injection, blow, extrusion and rotational Pipe, pipe fittings, surgical implants, coatings, wire and cable insulation... 

Polyvinyl Chloride (PVC) 1940 M-H VG G G G Extrusion, injection, rotational, slush, transfer, compression, blow mold Pipe conduit and fittings, cable insulation, downspouts, bottles, film... 

Cable coating extrusion, 29 548-549, 790 Cable insulating materials, mechanical and electrical properties of, 27 849t Cable insulation HDPE, 20 174-175 LLDPE, 20 208-209 Cable materials, in electronic materials packaging, 27 848... 

Ethylene copolymers with methyl methacrylate and ethyl, butyl, and methyl acrylates are similar to EVA products but have improved thermal stability during extrusion and increased low-temperature flexibility. The commercial products generally contain 15-30% of the acrylate or methacrylate comonomer. Applications include medical packaging, disposable gloves, hose, tubing, gaskets, cable insulation, and squeeze toys. 

Melt filtration systems are commonly employed in pigment master-batch production and in situations where the presence of defects in the compound may have a critical effect on its subsequent processing or properties. This is vitally important, for example, in fibre-spinning operations involving extrusion of polyester or polyamide through fine spinneret plates [162], and in minimizing breakdown of polymer cable insulation subjected to electrical stress [163]. 

Processing PCTFE is by the conventional methods (extrusion, injection, etc.) processing temperatures are high, and any degradation of PCTFE can cause severe corrosion and environmental problems. Applications include wire and cable insulation, electronic flexible printed circuits, packaging material (transparent film and sheet), pharmaceutical industry in particular strip and blister packs for tablets and capsules, etc. In the chemical industry, used as gaskets, 0-rings, valve seats, chemical tank liners, etc. 

Oparex 15 calcined calcium sulphate (Yesos Ibericos) was evaluated as a filler in plasticised PVC cable insulation compounds in comparison with two grades of calcium carbonate. Improvements were observed in tensile, electrical and low temperature properties, flammability and heat ageing characteristics and chemical resistance for calcium sulphate filled compounds, while no significant differences in water absorption and hydrolysis were noted. Studies of rheological properties showed improved processability in mixing and extrusion trials. URALITA... 

Extrusion-Applied Insulations. The polymers used in extrusion applications can be divided into two classes low-temperature applications and high-temperature applications. Polymers in the first category are poly(vinyl chloride), polyethylene, polypropylene, and their copolymers along with other elastomers. Polymers in the second category are mainly halocarbons such as Teflon polytetrafluoroethylene (which requires special extrusion or application conditions), fluoroethylene-propylene copolymer (FEP), perf luoroalkoxy-modified polytetrafluoroethylene (PFA), poly(ethylene-tetrafluoroethylene) (ETFE), poly(vinylidene fluoride) (PVF2) (borderline temperature of 135 °C), and poly(ethylene-chlorotrifluoroethylene). Extrusion conditions for wire and cable insulations have to be tailored to resin composition, conductor size, and need for cross-linking of the insulating layer. 

Initially, two-component, PVC/TPU blends were proposed [B. F. Goodrich Co., 1960], but soon, PVC/TPU blends with a modifier, e.g., ABS [Waugaman et al., 1963] NBR or PA [Kepes, 1959] were disclosed. Blending was also carried out by mixing PVC with polyols and isocyanates then polymerizing these two [Dainichiseika Color Chemicals, 1983]. Commercial PVC/TPU (with NBR) are represented by Duralex . The materials are usually formulated for extrusion, e.g., for wire and cable insulation, hoses and packaging. 

BP Chemicals have introduced a new technology for silane cross-linking in low-voltage cable insulations to produce more uniform cross-linking and greater shelf-life. The new silane-linked polyethylene compounds can be run on conventional extrusion equipment. The company has also produced a strippable double layer cable shield in cross-linkable polyethylene for medium voltage cables. 

MAJOR APPLICATIONS Film extrusion, packaging, wire and cable insulation, adhesives, coatings, and compounding. 

Low Density Polyethylene A branched-chain thermoplastic with density 0.91-0.94 g/cm. Has good impact strength, flexibility, transparency, chemical resistance, dielectric properties, and low water permeability and brittleness temperature, but poor heat, stress cracking, fire resistance, and weatherability properties. Processed by extrusion coating, injection and blow-molding, and film extrusion. Can be cross-linked. Used in packaging and shrink films, toys, bottle caps, cable insulation, and coatings. Also called LDPE. 

Pipes, film, profiles, cable insulation, and knot-free nets are produced by extrusion. Extrusion with broad slits, for example to produce 20-100-/Ltni-thick film, is a special case. The film is then chilled by cold rolling or by water baths (melt-molding or chill rolling process). Broad slits are also used in what is called the extrusion coating of paper or cardboard with, for example, poly(ethylene). Papers thus treated can then be heat sealed. 

Both swell and eccentricity are important to a variety of parts profiles that are made from extrusion operations. Sealing applications for automotive components, wire and cable insulation, flexible tuning, gaskets, and many other parts can be affected by swell and eccentricity characteristics. 

In extrusion, the preheated material is forced out of the extruder with a screw (Figure 12-2) or double screw and allowed to cool in a bath or in the air. Thermoplasts, elastomers, and thermosets are extruded. As a rule, thermosets are processed in torpedo-containing extruders. With thermosets, most of the curing reaction must occur in a heated pressure chamber. Pressures can approach several hundred bars. The rate of extrusion is lowest with thick-walled bodies. Tubes are extruded at rates of up to 10 m/min, films up to 150 m/min, and telephone-cable insulating material or fibers at up to 1000 m/min. In extrusion, the Barus effect (Section 11.3.1) and melt fracture (Section 7.6.1) may be observed. Tubes, films, ducts, cable insulation, and knot-free nets are produced by extrusion. 

One constant concern of additive suppliers is how to help their customers achieve higher production speeds. Ciba Specialty Chemicals makes the ease of addition of Irgastab Cable KVIO, a liquid antioxidant stabiliser for high voltage cable insulation, one of its selling points. It is used in conjimction with a peroxide crosslinking agent, and is said to allow increased cable extrusion speeds because it minimises gel formation. 

Dynamite Nobel AG introduced PVC flooring in Europe in 1934 under the trade name Nipolan. In USA the same product manufactured by Carbide and Chemical Co., was named Vinylite. In England in 1943, ICI and Distillers Co., commenced pilot-plant production of PVC, a material then in demand as a rubber substitute for cable insulation. After the war, developments were concerned largely with PVC-P, handled mainly by extrusion, calendering and paste techniques. 

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