A multiple screw extruder (50) combines application of vacuum to a vacuum vent (62) positioned between material feed locations (70, 72) of the extruder and use of specially configured extruder screws (58) to extract gases, primarily air, out of the extruder to densify the materials introduced into it and to extract unwanted fluid from material introduced for mixture with molten polymeric material flowing through the extruder. The multiple screw extruder is operationally versatile in that it is capable of carrying out the material densification and fluid extraction processes either separately or simultaneously. Implementation of the disclosed vacuum feed technology provides an increase in rate of extrudate throughput as compared with that achievable by implementation of atmospheric venting (16) in a conventionally configured extruder (10a, 10b).

Provided is a method for producing a shaping material that contains a cyclic olefin polymer and has a low content of a volatile impurity. This method for producing a shaping material is a method which includes passing a raw-material resin in a molten state through an extruder to produce a shaping material, and in which the extruder is equipped with a cylinder, a screw housed within the cylinder, a resin introduction port for introducing the raw-material resin into the cylinder, a resin discharge port for discharging the molten resin from the cylinder, a fluid injection port for injecting carbon dioxide or water into the cylinder between the resin introduction port and the resin discharge port, and a fluid discharge port for removing fluid in the cylinder by suction downstream of the fluid injection port and between the resin introduction port and the resin discharge port.

A method for producing a densified material includes: obtaining a film including at least one first layer of plastic material and one second layer with a composition distinct from the first layer, the first layer having a first melting temperature, or obtaining pieces of such a film; compressing the obtained film or the obtained pieces of film through at least one die of at least one extruder, and obtaining a profile of densified material, the extruder including at least one rotary endless screw pushing the obtained film or pieces of film along a screw axis; and optionally cutting the profile in order to obtain granules of densified material, the compression step being carried out at a maximum compression temperature for the obtained film or pieces of film, the maximum compression temperature being less than the first melting temperature. Also disclosed are installation and use of the densified material.

A co-rotating self-cleaning two-screw extruder with a gradual number of threads and through self-cleaning function, and a processing method using the same, are disclosed. The screw assembly in the extruder includes a first screw (3) and a second screw (4) that co-rotate at the same speed in engagement; the first screw (3) includes a first single threaded element, a first transition element, a multiple threaded element, a second transition element and a second single threaded element that are connected in sequence; and the second screw (4) includes a first single threaded element, a third transition element, a multiple threaded element, a fourth transition element and a second single threaded element that are connected in sequence. The materials are transferred by rotation of the first (3) and second screws (4), and get their respective compositions mixed based on the structure of a gradual number of threads; with the flow passage expanded, contracted and re-expanded in shape in sequence, the materials undergo the single-to-multiple threaded, multiple-to-single threaded and again single-to-multiple threaded chaotic mixing in sequence; and the first and second screws achieve the self-cleaning effect by wiping each other.

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.

A method of forming a thermoplastic polymer film includes melting and subjecting a polymer resin material to shear stresses in a range of 250 kPa to 400 kPa to form a refined resin material and forming the thermoplastic polymer film from the refined resin material. The film is substantially free of microgels having a largest dimension greater than 50 microns. The film has a thickness in a range of 15 micron to 80 microns. The film has a microgel count in a range of 0 to 0.2 per mm.sup.2 of microgels having the maximum dimension greater than 10 microns.

The present invention provides a system for continuous production of sulfur polymer cement. The system may include a series of high shear mixers, such as twin screw mixers or compounding extruders, to which a sulfur-containing starting material is added at one end, followed by at least one stage at which a sulfur modifier is added. Micro-aggregate may be added at one or more stages. At the discharge end of the continuous system, an extrudate is produced, and a pelletizer may be used to form pellets of the polymerized sulfur and micro-aggregate material. The pelletizer may comprise a flowing cooled water system, e.g., underwater pelletizer. The formed pellets may then go through a dryer system and then to a dry storage collection system.

The present invention provides a system for continuous production of sulfur polymer cement. The system may include a series of high shear mixers, such as twin screw mixers or compounding extruders, to which a sulfur-containing starting material is added at one end, followed by at least one stage at which a sulfur modifier is added. Micro-aggregate may be added at one or more stages. At the discharge end of the continuous system, an extrudate is produced, and a pelletizer may be used to form pellets of the polymerized sulfur and micro-aggregate material. The pelletizer may comprise a flowing cooled water system, e.g., underwater pelletizer. The formed pellets may then go through a dryer system and then to a dry storage collection system.

Provided is a method for producing a shaping material that contains a cyclic olefin polymer and has a low content of a volatile impurity. This method for producing a shaping material is a method which includes passing a raw-material resin in a molten state through an extruder to produce a shaping material, and in which the extruder is equipped with a cylinder, a screw housed within the cylinder, a resin introduction port for introducing the raw-material resin into the cylinder, a resin discharge port for discharging the molten resin from the cylinder, a fluid injection port for injecting carbon dioxide or water into the cylinder between the resin introduction port and the resin discharge port, and a fluid discharge port for removing fluid in the cylinder by suction downstream of the fluid injection port and between the resin introduction port and the resin discharge port.

A treatment element for treating material by means of a screw machine comprises a conveying section and a melting section. The melting section is arranged downstream of the conveying section in a conveying direction and is connected in one piece with the conveying section. This reduces wear and increases the service life.