Extruder-roll preheater

Drying of Solventless Double-Base Propellants. Since the manuf of solventless double-base proplnts is potentially hazardous, particularly rolling, drying, extruding machine operations, all such opns are performed by remote control. Following the final mixing, wringing screen opns, the water-wet paste is preheated to 90°F and fed by remote control into differential rollers in sufficient quantity to make two sheets. Hot water or steam is used to control... 

Screw extruders were first introduced into the rubber industry in the late 19th century by Francis Shaw, John Royle, and Paul Troester and became the basis of the machinery companies they created (Fig. 22). The original rubber extruders were hot-feed screw extruders, for which strips of rubber compound preheated on a two-roll mill were added to the extruder. The screws had deep channels and short length/diameter ratios. 

In extrusion coating (Fig. 5.53 ), a layer of molten polymer is applied to a substrate such as paper, plastic, or metal foil. When the substrate is fed into the extrusion line, it is often preheated and may be pretreated to enhance adhesion. Then an extruder pumps molten plastic onto the substrate. The coated material is then cooled by chill rolls and collected on a wind-up roll. Auxiliary equipment, such as slitters, corona discharge stations, and printing heads, may be placed between the chill and wind-up rolls. Since extrusion coating offers high production rates and ehmina-tion of solvent-based adhesives, it is frequently used for packaging. 

Example No. Width/Thickness of Extruded Film, cm/mm Latent Solvent /wt% Film Temperature at Machine Direction Stretch, °C Fast Roll Speed /Slow Roll Speed /MD Stretch Ratio, cm/min Preheating Air Temperature at Transverse Stretch, °C Width/ Thickness of the Oriented Film, cm/mm Temperature/ Duel Time iu DryiugZone, C/sec... 

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