Abstract An apparatus is disclosed for producing fiber reinforced plastics wherein the fibers are more uniformly dispersed throughout the resin. Briefly, the apparatus includes an extrusion means and a means for feeding glass fibers and thermoplastic resin thereto, said extrusion means comprising a two-stage extruder having a multiflight extruder screw extending through the two stages and defining within each stage, respectively, a feed zone, a transition zone and a metering zone, the compression ratio in the first stage being in the range of about 3:1 to 5:1, the compression ratio in the second stage being in the range of about 1.5:1 to 3.5:1, and the ratio of the flight depth of the extruder screw in the second stage feed zone to the flight depth of the extruder screw in the first stage feed zone being in the range of about 1:1.25 to 1:2.5, said extruder screw being provided with flow deflection means in the second stage metering zone to cause uniform dispersion of the fibers throughout the resin.
An apparatus according to claim 1 wherein the flow deflection means comprises a plurality of studs mounted on the extruder screw between the flights.
Claim 2
Dependent Claim
39 words
An apparatus according to claim 2 wherein the plurality of studs are arranged in groups, each group having a series of rows of studs with the studs of one row being offset to the studs of the adjacent rows.
Claim 3
Dependent Claim
22 words
An apparatus according to claim 2 wherein the studs are noncircular in cross section and are rotatably mounted on the extruder screw.
Claim 4
Dependent Claim
30 words
An apparatus according to claim 1 wherein the flow deflection means comprises a series of damming strips mounTed on the extruder screw and extending generally transversely between adjacent screw flights.
Claim 5
Dependent Claim
17 words
An apparatus according to claim 5 wherein the damming strips are substantially equally spaced from each other.
Claim 6
Dependent Claim
23 words
An apparatus according to claim 1 wherein a plurality of studs are mounted on the extruder screw in the first stage metering zone.
Claim 7
Dependent Claim
18 words
An apparatus according to claim 2 wherein the flights of the extruder screw are of constant pitch throughout.
Claim 8
Dependent Claim
240 words
In combination, an apparatus for producing glass fiber reinforced thermoplastic compositions comprising: A. supply means for providing continuous quantities of glass fibers and thermoplastic resin, B. feed means for simultaneously and continuously feeding the glass fibers and thermoplastic resin to an extrusion means, said feed means including a hopper, C. an extrusion means for receiving and processing the glass fibers and thermoplastic resin, said extrusion means including a two stage extruder having an uninterrupted multiflight extruder screw extending through the two stages and defining within each stage, in sequence, a feed zone, a transition zone and a metering zone; the flight depth and pitch in the first stage provide a compression ratio in the first stage in the range of about 3:1 to about 5:1, the flight depth and pitch in the second stage provide a compression ratio in the second stage in the range of about 1.5:1 to about 3.5:1, and the ratio of the flight depth in the second stage feed zone to the flight depth in the first stage feed zone being in the range of about 1:1.25 to about 1:2.5; said extruder screw being provided in the second stage metering zone with flow deflection means to cause improved dispersion of the glass fibers throughout the resin as the fibers and resin are processed therethrough, and D. cutting means for severing the glass fiber reinforced composition extrudate into a desired size for subsequent molding and extrusion operations.
Claim 9
Dependent Claim
17 words
The invention according to claim 9 wherein the flight pitch of the extruder screw is constant throughout.