A single-screw extruder for conveying and plasticizing a meltable material, including a screw and a heated cylinder, wherein the screw is rotatably held in the heated cylinder, the screw has a core and a helical main flight, which is at a first distance from the internal wall of the cylinder, a region of a transition zone and a melting zone has at least two successive, non-overlapping barrier portions, and a cylinder-side outside flight surface of one or more overflow flights is chamfered in full or in part over a flight width such that a conical gap that gets narrower in an overflow direction is formed between the internal wall of the cylinder and the cylinder-side outside flight surface.

The present invention relates to a method of producing a powder coating material containing a fluororesin and a non-fluororesin. The method of producing a powder coating material includes kneading a raw material containing the fluororesin and the non-fluororesin with a kneading extruder equipped with a screw having a kneading zone, wherein a ratio of a length L.sub.K of the kneading zone to an effective length L.sub.S of the screw (L.sub.K/L.sub.S×100) is 21.0 to 50.0%.

The present invention relates to a method of producing a powder coating material containing a fluororesin and a non-fluororesin. The method of producing a powder coating material includes kneading a raw material containing the fluororesin and the non-fluororesin with a kneading extruder equipped with a screw having a kneading zone, wherein a ratio of a length L.sub.K of the kneading zone to an effective length L.sub.S of the screw (L.sub.K/L.sub.S×100) is 21.0 to 50.0%.

A multi-shaft extruder which has screw shafts which are rotatable in the same direction and at the same speed, and which has at least one gas venting opening, and which has, in the entry region of said at least one gas venting opening, screw elements with a particularly large pitch or screw elements which have an asymmetric screw profile or which are mounted eccentrically on the axis of rotation of the screw shaft. The invention also relates to the use of the extruder according to the invention for processing or manufacturing plastic materials, and to the use of the screw elements with a particularly large pitch or the use of screw elements which have an asymmetric screw profile or which are mounted eccentrically on the axis of rotation of the screw shaft, in the region of the gas venting opening of a multi-shaft extruder.

A multi-shaft extruder which has screw shafts which are rotatable in the same direction and at the same speed, and which has at least one gas venting opening, and which has, in the entry region of said at least one gas venting opening, screw elements with a particularly large pitch or screw elements which have an asymmetric screw profile or which are mounted eccentrically on the axis of rotation of the screw shaft. The invention also relates to the use of the extruder according to the invention for processing or manufacturing plastic materials, and to the use of the screw elements with a particularly large pitch or the use of screw elements which have an asymmetric screw profile or which are mounted eccentrically on the axis of rotation of the screw shaft, in the region of the gas venting opening of a multi-shaft extruder.

An extruder comprising a housing having an inner recess; in which an extruder screw having a helical extruder screw flight is rotatably mounted. The outer diameter of the extruder screw is subdivided into a diameter start region, diameter central region, and diameter end region, wherein the diameter central region has a larger outer diameter than the other diameter regions, and a conical transition is formed in each case between regions at different diameters, and wherein at least one degassing zone formed in the diameter central region said degassing zone having a housing recess from which at least one suction opening extends to an outer side of the housing. The flow channel formed between the extruder screw shaft core and the inner wall of the housing recess is an annular expansion nozzle, wherein the outer diameter of the extruder screw flight is constant and the radial flow channel height increases.

An extruder comprising a housing having an inner recess; in which an extruder screw having a helical extruder screw flight is rotatably mounted. The outer diameter of the extruder screw is subdivided into a diameter start region, diameter central region, and diameter end region, wherein the diameter central region has a larger outer diameter than the other diameter regions, and a conical transition is formed in each case between regions at different diameters, and wherein at least one degassing zone formed in the diameter central region said degassing zone having a housing recess from which at least one suction opening extends to an outer side of the housing. The flow channel formed between the extruder screw shaft core and the inner wall of the housing recess is an annular expansion nozzle, wherein the outer diameter of the extruder screw flight is constant and the radial flow channel height increases.

An extruder for the viscosity-increasing preparation of meltable polymers, wherein an extruder screw with at least one helical extruder screw flight is positioned in a housing having an inner housing recess. A diameter central region has a larger outer diameter than at least one of the other diameter regions, and a conical transition is formed in each case between regions of different diameters. Two degassing zones are provided in the diameter central region, each of which has at least one associated suction opening in the housing, one degassing zone being designed in the region of the satellite screws and an additional degassing zone being designed upstream thereof in the flow direction. The thread depth of the screw threads, formed between the extruder screw flights is greater in both degassing zones than in at least one sealing and compression section formed therebetween.

An extruder for the viscosity-increasing preparation of meltable polymers, wherein an extruder screw with at least one helical extruder screw flight is positioned in a housing having an inner housing recess. A diameter central region has a larger outer diameter than at least one of the other diameter regions, and a conical transition is formed in each case between regions of different diameters. Two degassing zones are provided in the diameter central region, each of which has at least one associated suction opening in the housing, one degassing zone being designed in the region of the satellite screws and an additional degassing zone being designed upstream thereof in the flow direction. The thread depth of the screw threads, formed between the extruder screw flights is greater in both degassing zones than in at least one sealing and compression section formed therebetween.

The application relates to a plasticizing unit with a cylinder and a screw that is rotatably mounted in the cylinder and has a screw section which is designed as a shearing section and in which a blocking web encircling the screw core in a helical manner and a main screw thread enclosed by the blocking web are provided. A shearing web runs in the main screw thread parallel to the blocking web at a lower height than the blocking web. In this manner, two screw threads are produced which run parallel to each other and are separated by the shearing web. The threads are designed in the form of wave screw threads. Each wave screw thread is equipped with one or more wave peaks with a surface which is designed in the form of a plateau and forms a wave peak shearing surface, wherein the wave peak shearing surface is located at the same height as the surface of the shearing web in the region. The shearing web surface section which lies in the region of a wave peak shearing surface constitutes a shearing web sharing surface. A wave peak shearing surface and a shearing web shearing surface together form a total shearing surface. A specified total shearing surface together with the inner wall of the cylinder forms a shearing gap in accordance with a shearing gap size specified for the total shearing surface.