The extrusion device of the present invention must be capable of generating super-atmospheric pressures and elevated temperatures in the material being extruded. Preferably, the extruder employed is a twin screw extruder. The twin screwextruder houses two adjacent, parallel screws which are operated in a co-rotating mode. Suitable twin screw extruder can be obtained commercially and include, for example, a Baker-Perkins model MPF-50D twin screw extruder.
This formulation was compounded using the Werner Pfleiderer Model 53MM twin screw extruder to obtain a uniform blend. The two resins were dried in a desiccator hopper with a 0° F. dew point at 150° F. for eight hours afore getting extruded into pellets. During the banishment action the exhaustion aperture in the compression area of the spiral was acclimated to abolish damp and airy components. The broiled resins of the blush covering were fed into the extruder. The seven heating zones of the extruder were set: (1) 100° F., (2) 370° F., (3) 370° F., (4) 370° F., (5) 370° F., (6) 370° F., (7) 370° F. The spiral was maintained at 64 rpm application 600-670 H.P. and a agnate accepted of 54-59 amps. The cook temperature at the die was maintained for 367° F., and a awning backpack consisting of three altered wire meshes; 20, 40, 60 was acclimated to apple-pie the cook stream. The actual was pelletized. Press outs were acclimated to adviser the accord of the blend.
The formulation was compounded using a twin screw extruder to obtain uniform blended pellets. The two resins were dried before being extruded into pellets. During the extrusion process a vacuum vent in the compression zone of the screw was used to further remove moisture and other volatile components. The heating zones of the extruder were set at (1) 100° F., (2) 380° F., (3) 380° F., (4) 385° F., (5) 385° F., (6) 385° F. and (7) 385° F. The spiral was maintained at 70 rpm. The cook temperature of this conception was maintained at 380° F. and a awning backpack consisting of three altered wire meshes (20, 40 and 60) was acclimated to apple-pie the cook stream. This actual was pelletized and banishment coated on two mil top appearance Hostaphan 2000 polyester carrier film. The hot extrudate can anatomy a attenuate bright blur alignment from 0.1 mil to 2 mils thick. (The extruded actual had a cook bendability (Pas⋅sec) at 100, 500 and 1,000 sec-1 of about 888, 405 and 266, respectively; a melting temperature of about 147° C., and a Tg of about 23-33° C.) While faster band speeds aftereffect in a thinner film, faster spiral speeds aftereffect in thicker films. In this archetype a 1.75 inch lab extruder was acclimated to banishment covering a one mil PVDF copolymer/acrylic bright cape assimilate a two mil top appearance polyester carrier.