METHOD OF PRODUCING COMPOSITE FILAMENT FOR 3D PRINTING Russian patent published in 2024 - IPC B33Y70/00 C08J5/06 C08J5/24 B29C48/05 

FIELD: various technological processes.

SUBSTANCE: invention relates to production of composite materials and can be used in aircraft engineering, wind power engineering, land and water transport, in production of sports equipment and other industries for improving physical and mechanical properties of articles formed by three-dimensional printing. When making composite filament for three-dimensional printing, initial roving or bundle with diameter of 0.1-0.7 mm from carbon, glass, aramid, basalt fibres is impregnated with thermosetting binder, volume fraction of which is 20-40%. Heat treatment is carried out until complete hardening of the matrix material. Temperature conditions are set in accordance with the type and properties of the binder. Prepreg is coated with a layer of thermoplastic polymer by applying its melt and passed through a calibrating die to remove excess thermoplastic and obtain the required diameter of the composite filament. At the impregnation step, the binder and the roving or bundle of fibres are exposed to ultrasonic vibrations with amplitude of 12-15 mcm. Roving or bundle is passed through gap of 0.3-0.5 mm. Further, ultrasonic vibrations with amplitude of 2-3 mcm are applied to the calibrating die. After exiting the die, the obtained composite filament is exposed to a microwave electromagnetic field, the energy flow density and the exposure time of which are set depending on the electro- and thermophysical properties of the material of the reinforcing fibres. Enabling increase of volume of prepreg impregnation with thermosetting polymer by 1.5-1.7 times and 2-2.78 times at impregnation with thermoplastic polymer depending on frequency of oscillations in working zone. Increased uniformity of impregnation is provided. Full coverage of the prepreg surface with a thermoplastic polymer is provided, and as a result, better consolidation of separate filaments and monolayers during 3D printing.

EFFECT: higher strength of 3D printed articles.

5 cl, 27 dwg, 1 tbl