Device for producing plastic molded parts and the use thereof

A method for directly producing plastic moldings, the method comprising the steps of:

• providing an extruder;
• providing a molding tool arranged downstream of a discharge opening of the extruder;
• providing a screw guided in the extruder such that the screw is rotatable and is axially displaceable in order to transfer plasticized or liquid polymers, prepolymers and/or monomers present in the extruder into the molding tool;
• providing a nonreturn valve arranged in an area of a free end of the screw, wherein at least one locking ring of the nonreturn valve acts against an inner circumferential wall of the extruder and has a seal applied to at least part of an outer circumference of the locking ring, said seal sealing the locking ring against the circumferential wall of the extruder;
• providing the sealing material of the seal of the locking ring as a wear-resistant material selected from the group of polyether ketones (PEK) and derivatives thereof, polyaryl ether ketones (PAEK) and derivatives thereof, polyhalogenated polyolefins, especially polyfluorinated polyolefins, high-molecular-weight polyolefins with a molecular weight of at least 100,000 g/mole and polyamides (PA) including copolymers and polymer blends with same, with a hardness lower than that of material of the circumferential wall of the extruder;
• and
• charging liquid prepolymers and/or monomers, optionally together with plasticizable polymers and/or together with fillers and/or reinforcing fibers, as starting material into the extruder, transferring the material as a reaction mixture into the molding tool and curing the mixture.