The invention discloses a starch-based multi-channel airflow unit and a preparation method and an application thereof. The preparation method of the present invention comprises the following steps: melting a polylactic acid, wherein a temperature of a first temperature control zone is 135 C. to 145 C., a temperature of a second temperature control zone is 175 C. to 185 C., a temperature of a third temperature control zone is 190 C. to 200 C., and a temperature of a fourth temperature control zone is 175 C. to 185 C.; gelatinizing a starch-based material, adding the starch-based material in the third temperature control zone and fully mixing the mixture; adding a polyol in the third temperature control zone, and fully mixing the mixture; and extruding out the mixed material through twin screws, sizing in vacuum, cooling and sizing, and winding and cutting to obtain the starch-based multi-channel airflow unit.

A corrugator for an extrusion system for shaping a tubular plastic product, having a multiplicity of mould blocks, a guide track, along which the mould blocks are guided in each case in pairs during the operation of the corrugator from a starting region of the guide track towards an outlet region of the guide track, a first return track, along which the mould blocks are guided during the operation of the corrugator from the outlet region towards the starting region, and a second return track, with the aid of which individual mould blocks can be removed from the first return track and/or can be inserted into the latter during the operation of the corrugator.

Provided is a sizing die corresponding to a member installable between an extruder and a take-up machine, including a side surface in contact with an inner or outer surface of a tubular molten resin extruded toward the take-up machine through an annular die by the extruder, and causing the molten resin to flow along the side surface such that a shape of the molten resin matches a shape of the side surface, wherein the side surface includes a first region and a second region in an order of being close to the annular die in a flow direction of the molten resin, and surface roughness of the first region is smaller than surface roughness of the second region.

The method for extruding and labeling a packaging tube comprises the following successive steps: a) forming a partially or totally tubular label from a film in a shaper; b) inserting the label into a calibration element; c) extruding a tubular body at the concave-face side of the label in an extrusion head; d) bringing the outer face of the extruded tubular body into contact with the concave face of the label. In the method, the label comprises at least one layer of which the melting temperature is at least 20 C. higher than the melting temperature of the extruded tubular body. A first pressure difference is formed in the extruded tube with an air jet.