Patent ID: 9656408
Date: 2017-05-23
CPC Classifications: B29B,B29C,B29K,C08J,C08L

Claim:
1. A process for the production of thermoplastic molding compositions, where an extruder is used which consists essentially of the following, in the direction of conveying (in the direction of flow): a) at least one feed zone (DA) where a thermoplastic molding composition comprising water is introduced by means of feed equipment into the extruder, where said feed zone (DA) optionally comprises at least one dewatering aperture equipped with a metal-wire-mesh composite sheet (MV), a finely perforated metal sheet, or a slit diaphragm, b) at least one squeeze zone (Q) which serves to dewater the thermoplastic molding composition, which comprises at least one baffle, and which also comprises in each case at least one associated dewatering aperture, said at least one dewatering aperture being equipped with a metal-wire-mesh composite sheet (MV), a finely perforated metal sheet, or a slit diaphragm, c) at least one input zone (Z) where other components of the thermoplastic molding composition in the form of melt are introduced into the extruder, d) at least one plastifying zone (P) provided with mixing and/or kneading elements, e) at least one vent zone (E) which has at least one vent and in which further water or liquids are removed from the thermoplastic molding composition as vapor, where at least one of the vents is preferably equipped with a metal-wire-mesh composite sheet (MV), a finely perforated metal sheet, or a slit diaphragm, and f) a metering zone (AT) at which the thermoplastic molding composition is discharged from the extruder, where the squeeze zone (Q) in the process uses a screw-based extruder (S) in which the diameter (Ds) of at least one screw is from 30 to 230 mm, and where the rotation rate (DZ) of the at least one screw of the extruder is from 60 to 270 rpm, and where the screw-based extruder (S) used has at least one vent and/or dewatering aperture where there is, secured in the dewatering aperture, at least one metal-wire-mesh composite sheet (MV), with two or more layers, there being at least one smaller-mesh layer present on a coarsely woven, large-mesh but mechanically stable backing layer (first layer), where the location of the layer having the smallest mesh is on a side facing toward the product, and where the thermoplastic molding composition comprises at least one rubber-modified styrene-acrylonitrile (SAN) copolymer, with at least one acrylate-styrene-acrylonitrile (ASA) rubber with bimodal particle size distribution and an average particle size from 80 nm to 600 nm, and also with an SAN matrix with AN content from 25% by weight to 35% by weight.