Method for production of coated filaments for extrusion-based 3d printing processes

Abstract

The present invention relates to a novel process for the production of coated filaments for subsequent application as print in extrusion-based 3D printers, e.g. FDM printers (fused deposition modelling printers). The filaments are coated in a separate process outside of the printer, and can also be used in a conventional extrusion printer. The present invention further relates to the coating device for application of the coating to the filament and to a roll containing the coated filaments.

1 . A method to prepare coated filaments, comprising:
 supplying a solid filament in a form of a strand to a coating unit;   applying a coating composition comprising at least one of a pigment, an ink and an additive to the solid filament in the coating unit;   controlling the thickness of the coating on the solid filament; and   fixing the coating on the surface of the solid filament to obtain the coated filament;   wherein   the solid filament comprises a thermoplastically processable material, an acid soluble polymer, a base soluble polymer or a water soluble polymer, and   the coated filament is suitable for printing in a 3D extrusion process.   
     
     
         2 . The method according to  claim 1 , wherein the filament comprises a thermoplastically processable material which is selected from the group consisting of acrylonitrile-butadiene-styrene terpolymer (ABS), polycarbonate (PC), poly(meth)acrylate, polyphenylene sulphone (PPSU), high density polyethylene (HDPE), polyetherimide (PEI), polyether ether ketone (PEEK), polylactic acid (PLA) and a mixture thereof. 
     
     
         3 . The method according to  claim 1 , wherein applying the coating composition comprises at least one application technology selected from the group consisting of a nozzle application, application by a sponge material which surrounds the filament, application of the coating through an annular gap, and microextrusion. 
     
     
         4 . The method according to  claim 3 , wherein application of the coating comprises microextrusion and the coating is applied as a melt onto the surface of the filament. 
     
     
         5 . The method according to  claim 1 , wherein the coating application is controlled with a metering device. 
     
     
         6 . The method according to  claim 1 , wherein fixing the coating on the surface of the filament comprises at least one fixing method selected from the group consisting of thermal drying, application of a jet of air, application of a jet of a gas other than air, plasma treatment, UV irradiation, microwave radiation and magnetic induction. 
     
     
         7 . The method according to  claim 1 , further comprising winding the coated filament onto rolls for transport and storage. 
     
     
         8 . The method according to  claim 1 , wherein the solid filament comprises an acid soluble polymer, a base soluble polymer or a water soluble polymer, and the coated filament is suitable as a support material for a 3D extrusion printed object. 
     
     
         9 . The method according to  claim 1 , wherein the coating composition comprises an additive which is act vatable by microwaves, heat, plasma, UV light or magnetic fields. 
     
     
         10 . The method according to  claim 1 , wherein the coating composition further comprises at least one of an adhesion promoter and adhesive. 
     
     
         11 . The method according to  claim 1 , wherein the coating composition does not comprise a pigment or an ink and is colorless. 
     
     
         12 . The method according to  claim 1 , wherein the coating is uniform on the filament strand. 
     
     
         13 . The method according to  claim 1 , wherein the coating is not uniform on the filament strand. 
     
     
         14 . The method according to  claim 1 , wherein the coating is not uniform and comprises different colors on the filament strand. 
     
     
         15 . A coated filament obtained according to the method of  claim 1 . 
     
     
         16 . A coated filament obtained according to the method of  claim 2 . 
     
     
         17 . A coated filament obtained according to the method of  claim 8 . 
     
     
         18 . A coated filament obtained by the method of  claim 10 . 
     
     
         19 . A roll obtained according to  claim 7 .