摘要:
A process for concentrating polymers by evaporation is disclosed. The process entails (i) obtaining a mixture containing a polymer and volatile component, the volatile components being present in the mixture at an amount less than 20 wt. % relative to the weight of the mixture, and (ii) introducing the mixture in a downward direction under pressure through a plurality of nozzles arranged vertically and next to one another into a degassing container to form an extrudate. The volatile component contains at least one of residual monomers, oligomers and solvents, and the throughput of the mixture per nozzle is 0.3 to 2 kg/h. The vapor pressure of the volatile component of the extrudate is more than 2.5 bar, and the absolute pressure in the degassing container is 50 to 5000 Pa. The polymer prepared by the process is characterized in that it contains volatile components in an amount of less than 300 ppm.
摘要:
The invention relates to a process for extruding plastic compositions, in particular polymer melts and mixtures of polymer melts, above all thermoplastics and elastomers, particularly preferably polycarbonate and polycarbonate blends, also with the incorporation of other substances such as for example solids, liquids, gases or other polymers or other polymer blends with improved optical characteristics, with the assistance of a multi-screw extruder with specific screw geometries.
摘要:
The invention relates to a process for extruding plastic compositions. The process in particular relates to the conveying, kneading and/or mixing of plastic compositions, in particular of polymer melts and mixtures of polymer melts, above all thermoplastics and elastomers, particularly preferably polycarbonate and polycarbonate blends, also with the incorporation of other substances such as for example solids, liquids, gases or other polymers or other polymer blends.
摘要:
The invention relates to a process for extruding plastic compositions, in particular polymer melts and mixtures of polymer melts, above all thermoplastics and elastomers, particularly preferably polycarbonate and polycarbonate blends, also with the incorporation of other substances such as for example solids, liquids, gases or other polymers or other polymer blends with improved optical characteristics, with the assistance of a multi-screw extruder with specific screw geometries.
摘要:
The invention relates to a process for extruding plastic compositions, in particular polymer melts and mixtures of polymer melts, above all thermoplastics and elastomers, particularly preferably polycarbonate and polycarbonate blends, also with the incorporation of other substances such as for example solids, liquids, gases or other polymers or other polymer blends with improved optical characteristics, with the assistance of a multi-screw extruder with specific screw geometries.
摘要:
The invention relates to polycarbonates with extremely low residual levels of volatile constituents and thermal degradation products, and also improved optical properties, especially Yellowness Index (YI) and good thermal stability, from solvent-containing polymer melts. The invention further relates to an apparatus and a process for preparing these polycarbonates with the aid of a devolatilizing extruder with at least three devolatilizing zones, and zones for introducing entraining agent into dispersion are present upstream of at least three devolatilizing zones.
摘要:
The invention relates to polycarbonates with extremely low residual levels of volatile constituents and thermal degradation products, and also improved optical properties, especially Yellowness Index (YI) and good thermal stability, from solvent-containing polymer melts. The invention further relates to an apparatus and a process for preparing these polycarbonates with the aid of a devolatilizing extruder with at least three devolatilizing zones, and zones for introducing entraining agent into dispersion are present upstream of at least three devolatilizing zones.
摘要:
The invention relates to an apparatus and a process for devolatilizing solvent-containing polycarbonate solutions. By employing the inventive apparatus, polycarbonates with low residual values of volatile constituents are produced from solvent-containing polymer melts, which improved optical properties, especially yellowness index, with the aid of an apparatus combination of a flash devolatilizer and a vented extruder.
摘要:
The invention relates to an apparatus and a process for devolatilizing solvent-containing polycarbonate solutions. By employing the inventive apparatus, polycarbonates with low residual values of volatile constituents are produced from solvent-containing polymer melts, which improved optical properties, especially yellowness index, with the aid of an apparatus combination of a heatable tubular devolatilizer and a vented extruder.
摘要:
The invention is directed to an extruder (10), particularly for extruding a synthetic rubber product, which comprises a barrel (24), one or several extruder elements (12, 14), particularly one or several extruder screws and/or a kneader elements (14), arranged inside the barrel (24) for conveying the product, optionally an inlet port for feeding a stripping agent into the barrel (24) and an outlet port for removing volatile compounds from the product and, where applicable, the stripping agent. According to the invention a perforated die plate (26) is fixed to the barrel (24) in flow direction before the outlet port. Since the die plate (26) is not fixed to the extruder elements (12, 14) but to the barrel (24) a circumferential clearance between the die plate (26) and the barrel (24) is prevented so that no extruded material is passing the die plate (26) radially outside. Parts of the extruded material comprising a low surface area to volume ratio are prevented so that the evaporation of volatile compounds is facilitated.