Method for producing thermoplastic molding compounds, and thermoplastic molding compounds produced according thereto

Patent metadata

Field	Value
Publication number	US-9656408-B2
Application number	US-201414903830-A
Country	US
Kind code	B2
Filing date	Jul 8, 2014
Priority date	Jul 11, 2013
Publication date	May 23, 2017
Grant date	May 23, 2017

Abstract

A method for extruding thermoplastic molding compounds, the production of thermoplastic molding compounds taking place in a screw machine with mechanical dewatering, and impact-modified molding compounds or polymer blends which contain impact-modified thermoplastic materials that were produced by means of the method according to the invention.

First claim

What is claimed is:

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.

2. The process as claimed in claim 1 , characterized in that the thermoplastic molding composition comprises at least one rubber-modified styrene-acrylonitrile copolymer, where a rubber component is based on an acrylate-styrene-acrylonitrile copolymer or on a polybutadiene.

3. The process as claimed in claim 1 , characterized in that the thermoplastic molding composition comprises at least one impact-modified copolymer or one impact-modified copolymer blend, and also optionally other components, and
the thermoplastic molding composition is produced from a component comprising water, comprising up to 90% by weight of residual water, and said component is optionally mixed with the other components with devolatilization and/or dewatering, and then the thermoplastic molding composition is discharged from the extruder.

4. The process as claimed in claim 1 , characterized in that the process comprises, as at least one step, devolatilization and/or mechanical dewatering.

5. The process as claimed in claim 1 , characterized in that the diameter (Ds) of at least one screw of the screw-based extruder (S) is from 80 mm to 180 mm.

6. The process as claimed in claim 1 , characterized in that the rotation rate (DZ) of the at least one screw of the screw-based extruder (S) is from 100 rpm to 200 rpm.

7. The process as claimed in claim 1 , characterized in that the pressure in the squeeze zone (Q) of the screw-based extruder is from 10 bar to 55 bar.

8. The process as claimed in claim 1 , characterized in that the screw-based extruder (S) is equipped with at least two co- or contrarotating screws with diameter (Ds) from 30 mm to 230 mm.

9. The process as claimed in claim 1 , characterized in that the metal-wire-mesh composite sheet has from 2 to 30 layers.

10. The process as claimed in claim 1 , characterized in that the average mesh width of the smallest-mesh layer of the metal-wire-mesh composite sheet (MV) is from 1 μm to 500 μm.

11. A thermoplastic molding composition produced in an extruder by a process as claimed in claim 1 , 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.

12. The thermoplastic molding composition as claimed in claim 11 , comprising a butyl acrylate-styrene-acrylonitrile copolymer, and also an SAN copolymer, and optionally other components, characterized by less than 20 ppm content of 1-butene.

13. The thermoplastic molding composition as claimed in claim 11 , characterized by less than 50 ppm content of 1-butene, based on the total mass of the thermoplastic molding composition.

Assignees

• Ineos Styrolution Group Gmbh

Inventors

• Fischer Wolfgang
• Niessner Norbert

Classifications

• B29B7/842

  Removing liquids in liquid form · CPC title

• B29B7/42 Primary

  with screw or helix · CPC title

• B29B7/845

  Venting, degassing or removing evaporated components in devices with rotary stirrers · CPC title

• B29C48/09

  Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels · CPC title

• B29K2069/00

  Use of PC, i.e. polycarbonates {or derivatives thereof}, as moulding material · CPC title