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.

Disclosed is an asymmetric co-rotating multi-screw extrusion device, an extruder, and a processing method thereof. The barrel is provided with a feed port located at one end of the screw mechanism and a discharge port located at the other end of the screw mechanism, and the barrel comprises a conveying section, a melting section, an exhaust section, and a mixing extrusion section sequentially arranged from a side thereof where the feed port is located, wherein the exhaust section is provided with an exhaust hole. The screw mechanism comprises at least a first screw and a second screw arranged parallel to the first screw, wherein at least one of the first screw and the second screw has a cross-sectional profile comprising an arc forming a radial step between a root and a crest thereof, and the first screw and the second screw are asymmetrically inter-meshed and co-rotated at the same speed.

Disclosed is an asymmetric co-rotating multi-screw extrusion device, an extruder, and a processing method thereof. The barrel is provided with a feed port located at one end of the screw mechanism and a discharge port located at the other end of the screw mechanism, and the barrel comprises a conveying section, a melting section, an exhaust section, and a mixing extrusion section sequentially arranged from a side thereof where the feed port is located, wherein the exhaust section is provided with an exhaust hole. The screw mechanism comprises at least a first screw and a second screw arranged parallel to the first screw, wherein at least one of the first screw and the second screw has a cross-sectional profile comprising an arc forming a radial step between a root and a crest thereof, and the first screw and the second screw are asymmetrically inter-meshed and co-rotated at the same speed.

A shielding material fabricating apparatus according to the present invention includes: a mixing unit mixing a resin and a carbon fiber; an extrusion unit extruding a mixture obtained in the mixing unit; and a cutting unit cutting an extrudate extruded from the extrusion unit. The shielding material fabricating apparatus according to the present invention is capable of: reducing a manufacturing time and promoting simplification of a process when fabricating an electromagnetic wave shielding material; improving performance in mixing the resin and the carbon fiber, thereby fabricating an electromagnetic wave shielding material having a superior shielding rate; and cutting a metal-plated carbon fiber and simultaneously making the resin impregnated therein without a delay in time, thereby making it possible to use a long fiber as it is in a non-pelletized state.

Disclosed is an asymmetric co-rotating multi-screw extrusion device, an extruder, and a processing method thereof. The barrel is provided with a feed port located at one end of the screw mechanism and a discharge port located at the other end of the screw mechanism, and the barrel comprises a conveying section, a melting section, an exhaust section, and a mixing extrusion section sequentially arranged from a side thereof where the feed port is located, wherein the exhaust section is provided with an exhaust hole. The screw mechanism comprises at least a first screw and a second screw arranged parallel to the first screw, wherein at least one of the first screw and the second screw has a cross-sectional profile comprising an arc forming a radial step between a root and a crest thereof, and the first screw and the second screw are asymmetrically inter-meshed and co-rotated at the same speed.

Disclosed is an asymmetric co-rotating multi-screw extrusion device, an extruder, and a processing method thereof. The barrel is provided with a feed port located at one end of the screw mechanism and a discharge port located at the other end of the screw mechanism, and the barrel comprises a conveying section, a melting section, an exhaust section, and a mixing extrusion section sequentially arranged from a side thereof where the feed port is located, wherein the exhaust section is provided with an exhaust hole. The screw mechanism comprises at least a first screw and a second screw arranged parallel to the first screw, wherein at least one of the first screw and the second screw has a cross-sectional profile comprising an arc forming a radial step between a root and a crest thereof, and the first screw and the second screw are asymmetrically inter-meshed and co-rotated at the same speed.

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.S100) 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.S100) is 21.0 to 50.0%.

One embodiment provides a twin-screw extruder which is used to knead materials and has excellent productivity. The twin-screw extruder includes screws. The screws include double thread screws in which first screw portions engage with each other. Ratio D1/C of external diameter D1 of the first screw portion to a shaft distance C ranges from 1.25 to 1.40. The screws further include triple thread screws in which third screw portions engage with each other. Ratio D3/C of external diameter D3 of the third screw portion to the shaft distance C ranges from 1.05 to 1.10. External diameter D2 of a second screw portion decreases gradually from the first screw portion toward the third screw portion.

Processes for decrosslinking crosslinked plastic and devulcanizing vulcanized rubber include advancing such materials through single screw or twin screw extruders including special ultrasonic treatment zones wherein threadless shaft (single screw) or shafts (twin screw) rotate under an ultrasonic horn having a distal end aligned with the shaft or shafts and being shaped complimentary thereto. Special arcuate (single screw) or double-arcuate ultrasonic treatment flow paths confine the materials to flow under the horn where the material is subjected to ultrasonic waves to decrosslink the material, in the case of crosslinked plastic, or devulcanize the material, in the case of vulcanized rubber, with the extrudate leaving the die as a continuous stream or rope as is typical of virgin plastic or rubber.