Abstract: The invention relates to a spinneret for extruding self-crimping hollow fibers including at least one capillary. The at least one capillary has at least one segmented opening, which has at least two opening segments spaced apart from each other in the cross-section. A first opening segment of the at least two opening segments has a first opening-segment width and a second opening segment of the at least two opening segments has a second opening-segment width. The second opening-segment width is wider than the first opening-segment width.

Abstract: The invention pertains to an apparatus for premixing additives and feeding them into a polymer melt stream. The apparatus has a conducting element 2, first and a second intermediate element 4a and 4b, and a pump assembly 6, wherein the polymer melt stream is guided through channels 8 and 10 of the conducting element. The second intermediate element 4a has a feed element 12 that extends into the first channel 8 to form a ring channel. The feed element 12 is surrounded by openings 14, through which a portion of the polymer melt is drawn off, so that it can be mixed with an additive inside the pump assembly 6. This mixture is then returned via the feed element 12 to the polymer melt stream. The apparatus according to the invention makes it possible to decrease the residence times of the polymer and requires very little in the way of apparatus.

Abstract: The invention pertains to an apparatus for premixing additives and feeding them into a polymer melt stream. The apparatus has a conducting element 2, first and a second intermediate element 4a and 4b, and a pump assembly 6, wherein the polymer melt stream is guided through channels 8 and 10 of the conducting element. The second intermediate element 4a has a feed element 12 that extends into the first channel 8 to form a ring channel. The feed element 12 is surrounded by openings 14, through which a portion of the polymer melt is drawn off, so that it can be mixed with an additive inside the pump assembly 6. This mixture is then returned via the feed element 12 to the polymer melt stream. The apparatus according to the invention makes it possible to decrease the residence times of the polymer and requires very little in the way of apparatus.

Abstract: The present invention provides a process for mixing additives into a polymer melt steam, wherein a substream is removed from the polymer melt stream, mixed with additives, and then fed back into the polymer melt stream. In this process, the unmixed substream is sent as a single substream or in a maximum number of n−1 additional substreams directly to one up to a maximum number (n−1) of pump gear wheels of a planet wheel pump with n pump gear wheels. The additives are simultaneously supplied directly without mixing to at least one pump gear wheel of the planet wheel pump, and the substream mixed with the additives is removed from the planet wheel pump centrally at the inlet of the planet wheel pump and fed into the polymer melt stream.