A plasticating screw is proposed, with a screw channel, which runs spirally around a screw core, is laterally delimited by a flight (1), (2) and has flow elements (3), (4) that are distributed over its longitudinal direction, extend transversely over the screw channel and comprise a deep section (5) and a compression section (6), rising radially in the longitudinal direction. In order to design a plasticating screw of the type mentioned at the beginning in such a way that its length is reduced and good melting characteristics can be achieved even with little energy input, it is proposed that the compression section (6) forms at least one run-up surface (7), which is inclined towards the flight (1), (2) and is adjoined in the longitudinal direction by a plateau (8) for forming the flow.

A plasticating screw is proposed, with a screw channel, which runs spirally around a screw core, is laterally delimited by a flight (1), (2) and has flow elements (3), (4) that are distributed over its longitudinal direction, extend transversely over the screw channel and comprise a deep section (5) and a compression section (6), rising radially in the longitudinal direction. In order to design a plasticating screw of the type mentioned at the beginning in such a way that its length is reduced and good melting characteristics can be achieved even with little energy input, it is proposed that the compression section (6) forms at least one run-up surface (7), which is inclined towards the flight (1), (2) and is adjoined in the longitudinal direction by a plateau (8) for forming the flow.

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 method for manufacturing a foamed product uses a manufacturing apparatus having a plasticizing cylinder in which an introduction port for introducing a physical blowing agent into a starvation zone is formed, and an introduction speed adjustment container connected to the introduction port, wherein the manufacturing method comprises: turning a thermoplastic resin into a molten resin; introducing the physical blowing agent at a predetermined pressure into the starvation zone through the introduction speed adjustment container and maintaining the starvation zone at a predetermined pressure; setting the molten resin to a starved state; bringing the molten resin in the starved state and the pressurized fluid into contact with each other; and molding the molten resin into a foamed product. The maximum value of the inner diameter of the introduction speed adjustment container is larger than the inner diameter of the introduction port.

A conveyance portion, a barrier portion, and a path are provided at places of a screw main body in which a kneading portion is provided. In at least one of the places, the path is provided inside the screw main body, and includes an entrance and an exit. The entrance is opened to urge the raw materials having the conveyance limited by the barrier portion to increase pressure on the raw materials, to flow in the entrance. The raw materials flowing from the entrance flow through the path in the same direction as a conveyance direction of the conveyance portion.

A conveyance portion, a barrier portion, and a path are provided at places of a screw main body in which a kneading portion is provided. In at least one of the places, the path is provided inside the screw main body, and includes an entrance and an exit. The entrance is opened to urge the raw materials having the conveyance limited by the barrier portion to increase pressure on the raw materials, to flow in the entrance. The raw materials flowing from the entrance flow through the path in the same direction as a conveyance direction of the conveyance portion.

An extruder is disclosed including: a barrel; and a screw provided with a helical groove; wherein the screw comprises a dewatering portion comprising a first portion, and a second portion at a location downstream from the first portion; wherein, at the dewatering portion, clearance between the groove and the barrel decreases as one proceeds downstream; and wherein clearance reduction ratio at the first portion is greater than clearance reduction ratio at the second portion.

An extruder is disclosed including: a barrel; and a screw provided with a helical groove; wherein the screw comprises a dewatering portion comprising a first portion, and a second portion at a location downstream from the first portion; wherein, at the dewatering portion, clearance between the groove and the barrel decreases as one proceeds downstream; and wherein clearance reduction ratio at the first portion is greater than clearance reduction ratio at the second portion.

A conveyance portion, a barrier portion, and a path are provided at places of a portion of a screw main body in which a kneading portion is provided. In at least one of the places, an entrance is opened to cause raw materials, conveyance of which is limited by a barrier portion to increase pressure on the raw materials, to flow in. The raw materials flowing in from the entrance flow through the path in the opposite direction to a conveyance direction of the conveyance portion. An exit is opened in an outer circumferential surface of the screw main body at a position outside the conveyance portion in which the entrance is opened.