Method for producing a thermoplastic moulding compound
A method for producing a thermoplastic moulding compound by means of an extruder ( 10 ), which comprises at least one feed zone ( 20 ), at least one mixing section ( 30 ), at least one venting section ( 40 ) and at least one discharge zone ( 50 ), wherein in the at least one feed zone ( 20 ) a water-containing first component and a second component are supplied, in the at least one mixing section ( 30 ) the thermoplastic moulding compound is mixed and contained water is evaporated, in the at least one venting section ( 40 ) water vapour is removed from the moulding compound and in the at least one discharge zone ( 50 ) the moulding compound is discharged. At least one of the mixing housings ( 31, 32 ) is kept at a temperature that is equal to or lower than the temperature of the moulding compound within the mixing section ( 30 ).
1. A process for producing a thermoplastic molding composition by an extruder, comprising:
at least one feed zone,
at least one mixing section,
at least one venting section, and
at least one discharge zone,
wherein:
a water-containing first component of the thermoplastic molding composition and a second component of the thermoplastic molding composition are introduced in the at least one feed zone,
the thermoplastic molding composition is mixed and water present is evaporated in the at least one mixing section,
water vapor is removed from the thermoplastic molding composition in the at least one venting section, and
the thermoplastic molding composition is discharged in the at least one discharge zone, and
wherein:
at least one mixing barrel section of the mixing section is maintained at a temperature which is the same as or lower than the temperature of the thermoplastic molding composition within the mixing section,
a first mixing barrel section and/or a second mixing barrel section is/are operated adiabatically, and
at least one barrel section of the venting section is heated by temperature-control equipment in a manner such that the temperature of the at least one barrel section of the venting section is higher than the temperature of at least one mixing barrel section, and/or
at least one barrel section of the discharge zone is heated by temperature-control equipment in a manner such that the temperature of the at least one barrel section of the discharge zone is higher than the temperature of at least one mixing barrel section.
2. The process of claim 1 , wherein the temperature at which at least one mixing barrel section is maintained is lower by at least 10 K than the temperature of the thermoplastic molding composition within the mixing section.
3. The process of claim 1 , wherein at least one barrel section of the feed zone is heated by temperature-control equipment in a manner such that the temperature of the at least one barrel section of the feed zone is higher than the temperature of at least one mixing barrel section.
4. The process of claim 1 , wherein the water-containing first component of the thermoplastic molding composition and the second component of the thermoplastic molding composition are introduced together in the feed zone.
5. The process of claim 1 , wherein:
the at least one feed zone comprises:
at least one addition section,
at least one squeeze section, and
at least one input section,
wherein:
the water-containing first component of the thermoplastic molding composition is introduced in the at least one addition section,
the water-containing first component of the thermoplastic molding composition is to some extent dewatered in the at least one squeeze section, and
the second component of the thermoplastic molding composition is introduced in the at least one input section.
6. The process of claim 5 , wherein at least a portion of a barrel section of the input section is heated by temperature-control equipment in a manner such that the temperature of the portion of the barrel section of the input section is higher than the temperature of at least one portion of the mixing barrel section.
7. The process of claim 5 , wherein the water-containing first component introduced in the at least one addition section is a rubber.
8. The process of claim 7 , wherein the rubber comprises at least one polybutadiene.
9. The process of claim 7 , wherein the rubber comprises at least one acrylate rubber.
10. The process of claim 5 , wherein the second component introduced in the at least one input section is a styrene-acrylonitrile copolymer (SAN).
11. The process of claim 5 , wherein the second component is introduced as melt in the at least one input section.
12. The process of claim 2 , wherein the temperature at which at least one mixing barrel section is maintained is lower by at least 20 K than the temperature of the thermoplastic molding composition within the mixing section.
13. The process of claim 9 , wherein the rubber comprises at least one butyl acrylate rubber.