Provided is a method of producing a polyester by which the amount of cyclic oligomers in the polyester can be reduced to suppress deterioration of the quality.

An extruder includes a cylinder, a screw built in the cylinder, a dehydration cylinder block provided in the middle of the cylinder and discharging moisture that is separated from a resin material supplied into the cylinder. The dehydration cylinder block has a structure in which plate-shaped members each having an opening are arranged in a long-axis direction of the cylinder, a screw passing through the opening. Surface roughness of mutually opposing surfaces of the plurality of plate-shaped members is rougher than surface roughness of an inner wall of the cylinder.

The invention relates to a method for decontaminating recycled plastic materials, which comprises the steps of selecting, grinding, washing, rinsing, drying and decontaminating, wherein decontaminating is carried out by means of the steps of extracting and rinsing, and extracting is carried out using a water-soluble solvent having a boiling point greater than 180 C. at atmospheric pressure.

An extruder includes a cylinder, a screw built in the cylinder, a dehydration cylinder block provided in the middle of the cylinder and discharging moisture that is separated from a resin material supplied into the cylinder. The dehydration cylinder block has a structure in which plate-shaped members each having an opening are arranged in a long-axis direction of the cylinder, a screw passing through the opening. Surface roughness of mutually opposing surfaces of the plurality of plate-shaped members is rougher than surface roughness of an inner wall of the cylinder.

A method for the production of polyamide 6 pellets. The method includes, among other things, providing a melt of polyamide 6, feeding the melt into an underwater pelletizing system being operated with a fluid and producing pellets from the melt, transporting the pellets from the underwater pelletizing system with the fluid into an upper side of a vertical vessel having a cylindrical section and a tapered bottom section connected to a pipe comprising a screw and/or a rotary gate valve for conveying the pellets, and extracting of cyclic dimers and oligomers from the pellets, where the fluid is circulated between the underwater pelletizing system and the vertical vessel wherein a fraction thereof is withdrawn from circulation and the residual amounts of fluid leaving the vertical vessel with the pellets via the pipe and the withdrawn fraction are replenished with fresh fluid.

A method and material for 3D printing objects containing heat-sensitive molecules are disclosed. The composition consists of a water-saturated, polar thermoplastic polymer, such as highly hydrolyzed polyvinyl alcohol (PVA), into which functional moleculesproteins, peptides, pharmaceuticals, fragrances, or living cellsare dispersed. The polymer is first hydrated to form a gel, extruded and cut into pellets, then partially dried through a multi-stage dehydration process that leaves a moisture-rich core and a dry outer shell. During extrusion at typical FDM nozzle temperatures (200 C.), entrapped water within the material vaporizes at 100 C., providing in situ evaporative cooling and maintaining the temperature of the functional molecules below their degradation point. The process enables additive manufacturing of structurally sound objects that preserve the activity of heat-sensitive additives, opening new applications for 3D-printed consumables, pharmaceuticals, and bio-functional components.

A method for recycling polyester containers, in particular PET containers, said method including the following method steps: sorting the containers, comminuting the containers to produce flakes, friction washing the flakes, sorting the flakes, and extruding and granulating the cleaned flakes. The flake-sorting process is used to separate flakes which have a foreign polymer that is different from the polyester, and the flake-sorting process is a combination of a color-sorting process, a screening step, and polymer-sorting process.