WO2023247121A1 - Endless-fibre-reinforced 3d-printing filament and method for the production thereof - Google Patents

Endless-fibre-reinforced 3d-printing filament and method for the production thereof Download PDF

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Publication number
WO2023247121A1
WO2023247121A1 PCT/EP2023/063586 EP2023063586W WO2023247121A1 WO 2023247121 A1 WO2023247121 A1 WO 2023247121A1 EP 2023063586 W EP2023063586 W EP 2023063586W WO 2023247121 A1 WO2023247121 A1 WO 2023247121A1
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WO
WIPO (PCT)
Prior art keywords
reinforced
polymer
matrix polymer
printing
endless
Prior art date
Application number
PCT/EP2023/063586
Other languages
German (de)
French (fr)
Inventor
Michael Wilhelm
Philipp Rosenberg
Frank Henning
Original Assignee
Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
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Publication of WO2023247121A1 publication Critical patent/WO2023247121A1/en

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Classifications

    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D11/00—Other features of manufacture
    • D01D11/06—Coating with spinning solutions or melts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B15/00—Pretreatment of the material to be shaped, not covered by groups B29B7/00 - B29B13/00
    • B29B15/08—Pretreatment of the material to be shaped, not covered by groups B29B7/00 - B29B13/00 of reinforcements or fillers
    • B29B15/10—Coating or impregnating independently of the moulding or shaping step
    • B29B15/12—Coating or impregnating independently of the moulding or shaping step of reinforcements of indefinite length
    • B29B15/122—Coating or impregnating independently of the moulding or shaping step of reinforcements of indefinite length with a matrix in liquid form, e.g. as melt, solution or latex
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/28—Shaping operations therefor
    • B29C70/40—Shaping or impregnating by compression not applied
    • B29C70/50—Shaping or impregnating by compression not applied for producing articles of indefinite length, e.g. prepregs, sheet moulding compounds [SMC] or cross moulding compounds [XMC]
    • B29C70/504—Shaping or impregnating by compression not applied for producing articles of indefinite length, e.g. prepregs, sheet moulding compounds [SMC] or cross moulding compounds [XMC] using rollers or pressure bands
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/28—Shaping operations therefor
    • B29C70/40—Shaping or impregnating by compression not applied
    • B29C70/50—Shaping or impregnating by compression not applied for producing articles of indefinite length, e.g. prepregs, sheet moulding compounds [SMC] or cross moulding compounds [XMC]
    • B29C70/52—Pultrusion, i.e. forming and compressing by continuously pulling through a die
    • B29C70/521—Pultrusion, i.e. forming and compressing by continuously pulling through a die and impregnating the reinforcement before the die
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/28—Shaping operations therefor
    • B29C70/40—Shaping or impregnating by compression not applied
    • B29C70/50—Shaping or impregnating by compression not applied for producing articles of indefinite length, e.g. prepregs, sheet moulding compounds [SMC] or cross moulding compounds [XMC]
    • B29C70/52—Pultrusion, i.e. forming and compressing by continuously pulling through a die
    • B29C70/525—Component parts, details or accessories; Auxiliary operations
    • B29C70/527—Pulling means
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/38—Formation of filaments, threads, or the like during polymerisation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/10—Processes of additive manufacturing
    • B29C64/106—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material
    • B29C64/118—Processes of additive manufacturing using only liquids or viscous materials, e.g. depositing a continuous bead of viscous material using filamentary material being melted, e.g. fused deposition modelling [FDM]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y10/00—Processes of additive manufacturing

Definitions

  • Continuous fiber-reinforced 3D printing filament and method for its production The invention relates to a method for producing continuous fiber-reinforced 3D printing filaments, which have at least one thermoplastic matrix polymer with a plurality of continuous fibers extending primarily in the longitudinal direction of the 3D printing filament, by a plurality of continuous fibers is aligned according to their arrangement in the 3D printing filament and impregnated with the at least one thermoplastic matrix polymer, after which the endless strand obtained in this way is cut to length to form the continuous fiber-reinforced 3D printing filament.
  • the invention relates to a continuous fiber-reinforced 3D printing filament produced in this way, which has at least one thermoplastic matrix polymer with a plurality of continuous fibers extending primarily in the longitudinal direction of the 3D printing filament.
  • the melt layer process also known as “fused deposition modeling” (FDM) or “fused filament fabrication” (FFF), is known, which is used in 3D printers and represents a manufacturing process in which a 3D printing filament made of a thermoplastic polymer or a polymer blend of several thermoplastic polymers is plasticized and deposited in layers using a nozzle usually provided in the print head of the 3D printer in order to produce the polymer molded part ultimately formed from a large number of such layers generate.
  • FDM fuseposition modeling
  • FFF fused filament fabrication
  • this enables layer-by-layer production of relatively complex and, for example, conventional thermoplastic processing methods, such as injection molding, extrusion, which is also suitable for prototyping or small series. ren etc., molded parts with more or less complex structures that are impossible or difficult to produce, although the melt layer process is also increasingly being used for the series production of polymer molded parts with relatively complex structures.
  • a three-dimensional model of the molded part to be produced is usually created digitally, which can be done in particular using the known methods of Computer Aided Design (CAD).
  • CAD Computer Aided Design
  • slicer program e.g.
  • the three-dimensional model of the molded part to be produced is broken down into a plurality of thin layers, whereupon the plasticized polymer is moved accordingly using the nozzle Print head is deposited layer by layer to build up the molded part layer by layer.
  • the solidification process begins, with the deposited plastic solidifying, for example, at ambient temperature or under active cooling.
  • continuous fiber-reinforced 3D printing filaments have recently been used, which are plasticized and using the nozzle of the print head are then deposited in layers to form the polymer molding, not in the form of drops, but rather in the form of strands, so that the individual layers of the polymer molding produced in this way are reinforced with continuous fibers. are provided, the orientation and alignment of which can be controlled by the movement of the print head.
  • Such continuous fiber-reinforced 3D printing filaments which have at least one thermoplastic matrix polymer with a plurality of continuous fibers extending primarily in the longitudinal direction of the 3D printing filament, is carried out by arranging a plurality of continuous fibers in accordance with their arrangement in the 3D printing filament.
  • Printing filament is aligned and impregnated with the at least one thermoplastic matrix polymer, after which the endless strand thus obtained is cooled to solidify the matrix polymer and is cut to length to form the 3D printing filament.
  • Such a method for producing 3D printing filaments intended for additive manufacturing is known, for example, from DE 102018 213 337 A1, in which a hybrid yarn made of different fiber materials is heated, after which it is overmolded with a plasticized matrix material.
  • the latter can in particular be a thermoplastic polymer which is extruded in plasticized form onto the hybrid yarn or the hybrid yarn is overmolded with the plasticized polymer.
  • the known process for producing continuous fiber-reinforced 3D printing filaments is associated with a number of disadvantages. After impregnating the continuous fibers with the plasticized, liquid-viscous matrix polymer, on the one hand there is a very inhomogeneous fiber distribution in the 3D printing filament, and on the other hand, pores form due to gas inclusions between the continuous fibers, which are not sufficient during the impregnation process have been wetted with the plasticized matrix polymer. Both lead to inadequate strength and toughness of a continuous fiber filament produced by 3D printing using such 3D printing filaments.
  • the plastics deposited from the nozzle of the print head of 3D printers using the known continuous fiber-reinforced 3D printing filaments have very little toughness in the plasticized state, so that they are only based on the already printed layers of the produced polymer molding can be deposited or deposited, whereas it is particularly the case with 3D printing of continuous fiber-reinforced 3D printing filaments, which - as mentioned above - can only be deposited in strand form to form the printed polymer molding , in some applications for the production of three-dimensional structures of the polymer molding it would be desirable if the continuous fiber-reinforced plastic could be arranged more or less freely in three dimensions in space using the 3D printer, without it being supported by a base or is supported by an already printed layer of the polymer molding.
  • the invention is therefore based on the object of developing a method for producing continuous fiber-reinforced 3D printing filaments of the type mentioned in a simple and cost-effective manner in such a way that 3D printing filaments are as pore-free as possible while at least largely avoiding the aforementioned disadvantages with a very homogeneous distribution of the continuous fibers across the filament cross-section, the diameter and fiber size of which part increased compared to the state of the art and which in this way can be given greater toughness in the plasticized state. It is also aimed at an endless fiber-reinforced 3D printing filament produced in this way.
  • this object is achieved according to the invention in a method of the type mentioned at the outset in that the plurality of aligned continuous fibers are impregnated with a liquid reaction mixture which, on the one hand, at least one for polymerization to the at least one thermoplastic matrix polymer suitable liquid mono-, di- and/or oligomer, on the other hand at least one initiator and/or catalyst suitable for initiating the polymerization, after which the mono-, di- and/or oligomer is polymerized to form the matrix polymer.
  • the invention further provides a continuous fiber-reinforced 3D printing filament produced by such a method to solve this problem, which comprises at least one thermoplastic matrix polymer with a plurality of continuous fibers extending primarily in the longitudinal direction of the 3D printing filament having.
  • the embodiment according to the invention allows for a significantly lower viscosity compared to the plasticized matrix polymer of the continuous fiber-reinforced 3D printing filament.
  • the resulting better capillary effect during impregnation initially results in a significantly improved quality of the 3D printing filament produced in this way, on the one hand, a practically complete wetting of the endless fibers can take place and in this way pore formation is reliably avoided, on the other hand an extremely homogeneous fiber distribution is generated in the 3D printing filament, which leads to high strength and in particular toughness of a continuous fiber-reinforced polymer molded part printed herewith without defects .
  • the proportion of fibers in the 3D printing filament can be significantly increased, and it has been found that in this way 3D printing filaments can be produced with a proportion of fibers distributed very homogeneously over their cross section of up to approximately 70% to 80% by volume % by volume, based on the total volume of the 3D printing filament, can be processed using commercially available 3D printers, whereas previously known 3D printing filaments have a fiber content of a maximum of around 40% by volume to 50% by volume. exhibit.
  • the invention makes it possible to significantly increase the cross section or the diameter of the 3D printing filament compared to the prior art, and it has been found on the basis of experiments that, for example, in the invention - Continuous fiber-reinforced 3D printing filaments with a diameter of up to 15 mm, produced in accordance with this method, can be printed into a continuous fiber-reinforced polymer molding, whereas previously available 3D printing filaments provided with continuous fiber reinforcement usually have a diameter between approximately 0 .5 mm and about 1.75 mm. In a corresponding manner, according to the invention, thicker and therefore not only more stable but also more cost-effective continuous fibers can be used than was previously possible.
  • a further advantage of the invention is that the crystallinity and in particular the molecular weight of the matrix polymer produced in situ of the continuous fiber-reinforced 3D printing filament can be significantly increased, with a crystallinity of the matrix polymer that is up to approximately 50% higher than the prior art and an approximately ⁇ m 3 to 10 times larger molecular weight of up to about 1,000,000 g/mol to 1,200,000 g/mol can be achieved.
  • the risk of thermal impairment of the matrix polymer is significantly reduced compared to the prior art, since the matrix polymer polymerized in situ from the liquid mono-, di- and/or oligomers only needs to be melted once, if it is processed into a continuous fiber-reinforced polymer molding using a 3D printer using the melt layer process, whereas the conventional melt impregnation of the continuous fibers requires the matrix polymer to be melted at least twice.
  • the method according to the invention also ensures an improved energy and therefore cost efficiency compared to the state of the art, since no already finished matrix polymer has to be plasticized and melted.
  • the ability to adjust both the filament diameter and the molecular weight of the matrix polymer within very wide limits while at the same time ensuring a very homogeneous fiber distribution across the filament cross-section while avoiding pores as a result of insufficient impregnation enables the continuous fiber-reinforced 3D printing filament, especially during its processing in the melt layer process to give a very high level of rigidity and toughness using 3D printers, so that plastic strands of the continuous fiber-reinforced 3D printing filament discharged from the nozzle of the print head of 3D printers are not necessarily only deposited on already printed layers of a polymer molding produced. must be filed.
  • the invention surprisingly makes it possible for such a strand of plastic to be arranged more or less freely in three dimensions in space using the 3D printer, whereby it "stands still” in accordance with the movement path of the print head without collapsing due to gravity to fall onto an already printed layer of a polymer molded part, so that practically any three-dimensional structure can be created in accordance with the programmed movement of the print head, the fiber orientation of which can be specified by the movement of the print head.
  • supporting structures of components in skeletal or honeycomb construction should only be mentioned as examples.
  • continuous fiber-reinforced 3D printing filaments With continuous fiber-reinforced 3D printing filaments according to the invention, it is therefore possible for them to have a fiber volume fraction of up to about 80% by volume, for example between about 50% by volume and about 80% by volume, preferably between about 55% % by volume and about 80% by volume, between about 60% by volume and about 80% by volume or between about 65% by volume and about 80% by volume, in each case based on the total volume of the 3D printing filaments;
  • a continuous fiber-reinforced 3D printing filament according to the invention can therefore preferably have a fiber volume proportion in the aforementioned proportions.
  • the continuous fiber-reinforced 3D printing filaments according to the invention can have a diameter of up to about 15 mm, for example between about 2 mm and about 15 mm, preferably between about 3 mm and about 15 mm, between about 4 mm and about 15 mm or between about 5 mm and about 15 mm;
  • a continuous fiber-reinforced 3D printing filament according to the invention can therefore preferably have a diameter in the aforementioned dimensions.
  • the continuous fiber-reinforced 3D printing filaments according to the invention can have a molecular weight of the thermoplastic matrix polymer of up to about 1,200,000 g/mol, for example between about 300,000 g/mol and about 1,200,000 g/mol, between about 400,000 g/mol and about 1,200,000 g/mol, between about 500,000 g/mol and about 1,200,000 g/mol or between about 600,000 g/mol and about 1,200,000 g/mol;
  • a continuous fiber-reinforced 3D printing filament according to the invention can therefore preferably have a molecular weight in the aforementioned sizes.
  • any known thermoplastic polymers including copolymers and their blends, such as those from the group of polyamides, for example cast polyamides and/or anionic polyamides, such as polyamide-6, can be considered as the matrix polymer of the continuous fiber-reinforced 3D printing filaments according to the invention (PA6), polyamide-12 (PA12) and the like, - the polyolefins, for example polyethylene, polypropylene (PP), polybutylene (PB) and the like, - the thermoplastic polyurethanes (TPU), and - the thermoplastic polyesters, for example polymethacrylates, polyalkylene terephthalates , such as polyethylene (PET), polypropylene (PPT), polybutylene terephthalate (PBT) etc., and the like.
  • PA6 matrix polymer of the continuous fiber-reinforced 3D printing filaments according to the invention
  • PA12 polyamide-12
  • - the polyolefins for example polyethylene, polypropylene (PP
  • liquid mono-, di- and/or oligomers used to impregnate the continuous fibers depends on the respective matrix polymer to be produced in situ, with in the case of the aforementioned polyamides, for example, caprolactams, laurolactams, aminocarboxylic acids or diamines Connection with dicarboxylic acids can be used.
  • the liquid impregnation monomers that can be used are, for example, ethylene, propylene, butylene and the like, whereas in the case of thermoplastic polyurethanes, for example, corresponding diisocyanates can be used in conjunction with corresponding diols.
  • liquid waterproofing monomers for thermoplastic polyesters include methacrylic acid, lactones, dicarboxylic acids in combination with di- oils, such as terephthalic acid in combination with ethanediol, 1,3-propanediol, 1,4-butanediol, etc.
  • at least a first liquid component which contains at least one liquid mono-, di- and / or contains oligomer, and at least one second liquid component, which contains the initiator and / or catalyst, is kept separately in stock and mixed to form the liquid reaction mixture immediately before the plurality of aligned continuous fibers are impregnated.
  • the matrix polymer of the continuous fiber-reinforced 3D printing filament to be polymerized in situ contains, for example, a plurality of different mono-, di- and/or or oligomers required.
  • the plurality of continuous fibers can preferably be unwound essentially continuously from at least one spool, in particular from a plurality of spools become.
  • the plurality of continuous fibers can preferably be preheated and/or dried before impregnation with the liquid reaction mixture in order, on the one hand, to eliminate any residual moisture content of the continuous fibers and, on the other hand, to bring the continuous fibers to the required temperature of the polymerization reaction.
  • the plurality of aligned continuous fibers can then advantageously be impregnated with the liquid reaction mixture in a pultrusion tool and the liquid reaction mixture can be formed into the thermoplastic matrix polymer is polymerized.
  • the continuous fibers can in particular be guided through a nozzle channel of the pultrusion tool, in which they are impregnated with the liquid reaction mixture and in which the latter is polymerized in situ to form the matrix polymer.
  • a jacket layer made of at least one further thermoplastic polymer is extruded onto the endless strand formed from the continuous fibers impregnated with the thermoplastic matrix polymer, the further thermoplastic polymer being lymer of the jacket layer in particular - the same polymer as the matrix polymer, but with a different, in particular lower, molecular weight, - a different polymer but compatible with the matrix polymer, and / or - a polymer mixed with at least one additive acts.
  • the polymer of the sheath layer can expediently be extruded onto the matrix polymer after essentially complete polymerization in order to give the continuous fiber-reinforced 3D printing filament and in particular also an endless fiber-reinforced polymer molded part thereby produced by means of the melt layer process additional properties to rent.
  • the jacket layer made of the further polymer can serve for improved adhesion or weldability of a further layer made of plastic strands of the continuous fiber-reinforced 3D printing filament printed onto an already printed layer of a polymer molded part, or at least one
  • additives such as electrically conductive ones, can also be added to the polymer of the jacket layer and/or magnetic fillers, dyes, pigments and the like.
  • a continuous fiber-reinforced 3D printing filament produced in this way it can therefore be provided that it has a sheath layer made of at least one further thermoplastic polymer, whereby the further thermoplastic polymer of the sheath layer is in particular - the same polymer as the matrix polymer, but with a different, in particular lower, molecular weight, - a different polymer but compatible with the matrix polymer, and / or - a polymer mixed with at least one additive.
  • the endless strand formed from the continuous fibers impregnated with the thermoplastic matrix polymer can be conveyed essentially continuously for the purpose of a continuous or semi-continuous feed, in particular by moving it between rollers or belts driven in opposite rotation with the rotation speed of which the respective feed speed can be controlled.
  • the endless strand formed from the continuous fibers impregnated with the thermoplastic matrix polymer can ultimately expediently be wound onto a roll and cut to length into wound continuous fiber-reinforced 3D printing filaments; or - cut to length into continuous fiber-reinforced 3D printing filaments that extend essentially in a straight line become.
  • a substantially continuous conveyance of the endless strand can also take place by means of a drive of the roller onto which the finished endless fiber-reinforced 3D printing filament is wound, so that no additional tensile force using rotationally driven rollers or belts is necessary.
  • FIG. 1 shows a schematic view of a device for producing continuous fiber-reinforced 3D printing filaments, which is used for the continuous or semi-continuous production of the continuous fiber-reinforced 3D printing filaments in the manner of the pultrusion process.
  • the device comprises a supply station 1 with a plurality of spools 2 on which the continuous fibers 3 to be processed made of any known materials are wound. In the conveying direction of the endless fibers 3 (from left to right in FIG.
  • the storage station 1 is followed by a preheating and drying station 4, through which the endless fibers unwound from the spools 2 fibers 3 can be passed through.
  • the preheating and drying station 4 can also serve to align the continuous fibers 3 according to their intended arrangement in the continuous fiber-reinforced 3D printing filament to be produced, for example in order to align them according to its desired cross-sectional shape.
  • a separate alignment station for the continuous fibers 3 can of course be provided as an alternative or in addition to the preheating and drying station 4 (not shown).
  • a pultrusion tool 5 in the nozzle channel 6 of which the aligned continuous fibers 3 can be impregnated with a liquid reaction mixture which, on the one hand, contains at least one liquid monomer suitable for polymerization into the thermoplastic matrix polymer. , di- and/or oligomer, on the other hand contains at least one initiator and/or catalyst suitable for initiating the polymerization.
  • the pultrusion tool 5 comprises an inlet channel 7 which is connected to the nozzle channel 6 and which opens into a mixing chamber 8, which in turn is connected to two or more separate storage containers 9, 10.
  • the pultrusion tool 5 can, for example, be followed by a further pultrusion tool (not shown in the drawing) according to the prior art, which is used to extrude a plasticized polymer the jacket layer on the continuous fiber reinforced endless strand 14 is designed, which is formed from the endless fibers 3 impregnated with the thermoplastic matrix polymer.
  • a feed station 11 Downstream of the pultrusion tool 5, this is followed by a feed station 11, which has, for example, two or more rotating belts 12, 13 driven in accordance with the desired feed, between which the from which the now with the thermo - Endless strand 14 formed by plastic matrix polymer impregnated endless fibers can be guided through.
  • a winding station 15 downstream of the feed station 11 there is finally a winding station 15, which is used to wind the endless fiber-reinforced 3D printing filaments 17 produced onto a roll 16, which in turn can be rotationally driven in a controlled manner in accordance with the desired feed.
  • a cutting device 18 arranged between the feed station 11 and the winding station 15 is used to cut the endless strand 14, which is formed from the endless fibers 3 impregnated with the thermoplastic matrix polymer, into the continuous fiber-reinforced 3D printing filaments.
  • a plurality of continuous fibers 3 are unwound essentially continuously from the spools 2 of the supply station 1, with the feed speed of the continuous fibers 3 being determined by the rotational speed of the rotating belts 12, 13 the feed station 11 can be controlled.
  • the continuous fibers 3 are transferred to the preheating and drying station 4 in order, on the one hand, to remove any residual moisture and to preheat the continuous fibers 3 to the polymerization temperature and, on the other hand, to heat them accordingly Arrangement in the 3D printing filament 17, in particular according to the desired cross-sectional shape (cf. the schematic cross-sectional view A of the essentially circularly aligned endless fibers 3 in the present case according to FIG. 1).
  • the aligned continuous fibers 3 then enter the nozzle channel 6 of the pultrusion tool 5, where they are impregnated with a liquid reaction mixture, which is fed to the nozzle channel 6 from the mixing chamber 8 via the inlet channel 7.
  • the liquid reaction mixture is formed, for example, from two components stored separately from one another in the two separate storage containers 9, 10, one of which, for example, contains one or more liquid components suitable for polymerization to form the matrix polymer. s) contains mono-, di- and/or oligomer(s) and other initiators, catalysts or the like suitable for activating the polymerization.
  • a monomer of the liquid reaction mixture can be, for example, ⁇ -caprolactam, which is converted into polycaprolactam (polyamide-6) as a matrix polymer using suitable initiators, such as in the form of alcoholates, by means of anionic chain polymerization.
  • suitable initiators such as in the form of alcoholates
  • the endless strand 14 produced in this way which is formed from the endless fibers 3 impregnated with the thermoplastic matrix polymer, is then guided between the rotating belts 11, 12 of the feed station. Downstream of the feed station, the endless strand 14 is finally cut to length by means of the cutting device 18 according to the desired length to form the endless fiber-reinforced 3D printing filaments 17, which in the present case have previously been wound onto the roll(s) 16 of the winding station 15.
  • the endless strand 14 is also possible instead to cut the endless strand 14 to length into essentially straight continuous fiber-reinforced 3D printing filaments (not shown), which can then be assembled and packaged.
  • FIG. 2 shows a microscopic view of the cross section of a continuous fiber-reinforced 3D printing filament produced in a conventional manner by means of melt impregnation, whereby on the one hand a very inhomogeneous distribution of the continuous fibers and on the other hand a plurality of pores marked with circular borders can be seen , which arose due to incomplete wetting with the liquid-viscous melt of the plasticized matrix polymer in some areas.
  • 3 shows a microscopic photograph of the cross section of a continuous fiber-reinforced 3D printing filament produced by means of the method according to the invention, as explained above with reference to FIG A significantly larger proportion of fibers has a very homogeneous fiber distribution and is free of pores.
  • such a Continuous fiber-reinforced polymer molded parts created using a 3D printing filament using the melt layer process not only have a significantly higher quality, especially in terms of their toughness, stiffness and strength, but also open up new areas of application for the continuous fiber-reinforced 3D printing filament, in particular the possibility of 3D printing -Printing of continuous fiber-reinforced molded part structures as freely as possible in three dimensions in space.

Abstract

The invention relates to a method for producing endless-fibre-reinforced 3D-printing filaments which comprise a thermoplastic matrix polymer having a plurality of endless fibres extending in the longitudinal direction of the 3D-printing filament. According to the invention, the plurality of oriented endless fibres is impregnated with a liquid reaction mixture which contains, on the one hand, a liquid monomer, dimer and/or oligomer suitable for polymerisation to give the thermoplastic matrix polymer, and, on the other hand, an initiator and/or catalyst suitable for initiating the polymerisation, after which the monomer, dimer and/or oligomer is polymerised in situ to form the matrix polymer. The endless strand obtained in this way is then trimmed to length to give the endless-fibre-reinforced 3D-printing filament. The invention further relates to an endless-fibre-reinforced 3D-printing filament produced in such a way.

Description

Endlosfaserverstärktes 3D-Druckfilament und Verfahren zu seiner Herstellung Die Erfindung betrifft ein Verfahren zur Herstellung von endlosfaserverstärkten 3D-Druckfilamenten, welche wenigs- tens ein thermoplastisches Matrixpolymer mit einer Mehrzahl an sich vornehmlich in Längsrichtung des 3D-Druckfilamentes erstreckenden Endlosfasern aufweisen, indem eine Mehrzahl an Endlosfasern entsprechend ihrer Anordnung in dem 3D- Druckfilament ausgerichtet und mit dem wenigstens einen thermoplastischen Matrixpolymer imprägniert wird, wonach der derart erhaltene Endlosstrang zu dem endlosfaserver- stärkten 3D-Druckfilament abgelängt wird. Darüber hinaus bezieht sich die Erfindung auf ein solchermaßen hergestell- tes endlosfaserverstärktes 3D-Druckfilament, welches we- nigstens ein thermoplastisches Matrixpolymer mit einer Mehrzahl an sich vornehmlich in Längsrichtung des 3D- Druckfilamentes erstreckenden Endlosfasern aufweist. Zur Herstellung von Polymer-Formteilen ist das auch als "fused deposition modeling" (FDM) oder "fused filament fabrication" (FFF) bezeichnete Schmelzschichtverfahren be- kannt, welches in 3D-Druckern Anwendung findet und ein Fer- tigungsverfahren darstellt, bei welchem ein 3D-Druck- filament aus einem thermoplastischen Polymer oder aus einem Polymer-Blend aus mehreren thermoplastischen Polymeren plastifiziert und mittels einer üblicherweise im Druckkopf des 3D-Druckers vorgesehenen Düse schichtweise abgeschieden wird, um das letztlich aus einer Vielzahl an solchen Schichten gebildete Polymer-Formteil zu erzeugen. Dies er- möglicht einerseits eine auch zum Prototyping oder für Kleinserien geeignete, schichtweise Herstellung von relativ komplexen und beispielsweise durch herkömmliche thermoplas- tische Verarbeitungsverfahren, wie Spritzgießen, Extrudie- ren etc., nicht oder nur schwer herstellbaren Formteilen mit mehr oder minder komplexen Strukturen, wobei das Schmelzschichtverfahren andererseits zunehmend auch für die Serienfertigung von Polymer-Formteilen mit relativ komple- xen Strukturen eingesetzt wird. Bei dem Schmelzschichtverfahren mittels auch als "addi- tive manufacturing" bezeichneten 3D-Druckens wird üblicher- weise ein dreidimensionales Modell des zu erzeugenden Form- teils digital erstellt, was insbesondere mittels der be- kannten Methoden des Computer Aided Designs (CAD) geschehen kann. Darüber hinaus wird mittels einer geeigneten Soft- ware, wie beispielsweise eines sogenannten Slicer-Programms (z.B. CuraTM oder dergleichen), das dreidimensionale Modell des zu erzeugenden Formteils in eine Mehrzahl an dünnen Schichten zerlegt, woraufhin das plastifizierte Polymer mittels der Düse des entsprechend bewegten Druckkopfes schichtweise abgeschieden wird, um das Formteil Schicht für Schicht aufzubauen. Unmittelbar nach dem Ausbringen des mehr oder minder strang- oder tropfenförmig aus der Düse des Druckkopfes ausgetragenen Polymerplastifikates beginnt der Erstarrungsprozess, wobei das abgeschiedene Plastifikat beispielsweise bei Umgebungstemperatur oder auch unter ak- tiver Abkühlung erstarrt. Um mittels des 3D-Druckens endlosfaserverstärkte Poly- mer-Formteile erzeugen zu können, kommen in jüngerer Zeit neben herkömmlichen 3D-Druckfilamenten aus thermoplasti- schen Polymeren auch endlosfaserverstärkte 3D-Druckfila- mente zum Einsatz, welche plastifiziert und mittels der Dü- se des Druckkopfes dann nicht tropfenförmig, sondern strangförmig schichtweise zu dem Polymer-Formteil abge- schieden werden, so dass die einzelnen Schichten des derart erzeugten Polymer-Formteils mit einer Endlosfaserverstär- kung versehen sind, deren Orientierung und Ausrichtung durch die Bewegung des Druckkopfes gesteuert werden kann. Die Herstellung von solchen endlosfaserverstärkten 3D- Druckfilamenten, welche wenigstens ein thermoplastisches Matrixpolymer mit einer Mehrzahl an sich vornehmlich in Längsrichtung des 3D-Druckfilamentes erstreckenden Endlos- fasern aufweisen, erfolgt dabei dadurch, indem eine Mehr- zahl an Endlosfasern entsprechend ihrer Anordnung in dem 3D-Druckfilament ausgerichtet und mit dem wenigstens einen thermoplastischen Matrixpolymer imprägniert wird, wonach der derart erhaltene Endlosstrang abgekühlt, um das Matrix- polymer zu erstarren, und zu dem 3D-Druckfilament abgelängt wird. Ein solches Verfahren zur Herstellung von zur additi- ven Fertigung vorgesehenen 3D-Druckfilamenten ist z.B. aus der DE 102018 213 337 A1 bekannt, indem ein Hybridgarn aus verschiedenen Fasermaterialien erwärmt wird, wonach es mit einem plastifizierten Matrixmaterial umspritzt wird. Bei letzterem kann es sich insbesondere um ein thermoplasti- sches Polymer handeln, welches in plastifizierter Form auf den Hybridgarn aufextrudiert wird oder der Hybridgarn wird mit dem plastifizierten Polymer umspritzt. Indes hat sich gezeigt, dass mit dem bekannten Verfahren zur Herstellung von endlosfaserverstärkten 3D-Druckfilamen- ten eine Reihe an Nachteilen einhergeht. So ergibt sich nach der Imprägnierung der Endlosfasern mit dem plastifi- zierten, flüssig-viskosen Matrixpolymer einerseits eine sehr inhomogene Faserverteilung in dem 3D-Druckfilament, andererseits kommt es zur Porenbildung infolge Gasein- schlüssen zwischen den Endlosfasern, welche während des Im- prägniervorgangs nicht hinreichend mit dem plastifizierten Matrixpolymer benetzt worden sind. Beides führt zu einer mangelhaften Festigkeit und Zähigkeit eines mittels solcher 3D-Druckfilamente durch 3D-Drucken erzeugten, endlosfaser- verstärkten Polymer-Formteils. Dies gilt um so mehr mit zu- nehmender Dicke und mit zunehmendem Faseranteil des endlos- faserverstärkten 3D-Druckfilamentes, so dass sowohl seinem maximalen Durchmesser als auch seinem Fasergehalt enge Grenzen gesetzt sind, wobei herkömmliche, gegenwärtig ver- fügbare 3D-Druckfilamente eine maximale Dicke von etwa 1,75 mm und einen maximalen Faseranteil von etwa 40 Vol.-%, bezogen auf das Gesamtvolumen des 3D-Druckfilamentes, be- sitzen. Darüber hinaus weisen die unter Verwendung der be- kannten endlosfaserverstärkten 3D-Druckfilamente aus der Düse des Druckkopfes von 3D-Druckern abgeschiedenen Plasti- fikate aufgrund der vorgenannten Defizite eine nur sehr ge- ringe Zähigkeit im plastifizierten Zustand auf, so dass sie lediglich auf den bereits gedruckten Schichten des erzeug- ten Polymer-Formteils abgeschieden bzw. abgelegt werden können, wohingegen es insbesondere beim 3D-Drucken von end- losfaserverstärkten 3D-Druckfilamenten, welche - wie oben erwähnt - nur strangförmig zu dem gedruckten Polymer-Form- teil abgeschieden werden können, in einigen Anwendungsfäl- len zur Erzeugung von dreidimensionalen Strukturen des Po- lymer-Formteils wünschenswert wäre, wenn das endlosfaser- verstärkte Plastifikat mittels des 3D-Druckers auch mehr oder minder frei dreidimensional im Raum angeordnet werden könnte, ohne dass es von einer Unterlage oder einer bereits gedruckten Schicht des Polymer-Formteils abgestützt wird. Der Erfindung liegt daher die Aufgabe zugrunde, ein Ver- fahren zur Herstellung von endlosfaserverstärkten 3D-Druck- filamenten der eingangs genannten Art auf einfache und kos- tengünstige Weise dahingehend weiterzubilden, dass unter zumindest weitestgehender Vermeidung der vorgenannten Nach- teile möglichst porenfreie 3D-Druckfilamente mit einer sehr homogenen Verteilung der Endlosfasern über den Filament- querschnitt erhalten werden, deren Durchmesser und Faseran- teil gegenüber dem Stand der Technik erhöht und welchen auf diese Weise eine höhere Zähigkeit im plastifizierten Zu- stand verliehen werden kann. Sie ist ferner auf ein sol- chermaßen hergestelltes endlosfaserverstärkten 3D-Druck- filament gerichtet. In verfahrenstechnischer Hinsicht wird diese Aufgabe er- findungsgemäß bei einem Verfahren der eingangs genannten Art dadurch gelöst, dass die Mehrzahl an ausgerichteten Endlosfasern mit einer flüssigen Reaktionsmischung impräg- niert wird, welche einerseits wenigstens ein zur Polymeri- sation zu dem wenigstens einen thermoplastischen Matrixpo- lymer geeignetes flüssiges Mono-, Di- und/oder Oligomer, andererseits wenigstens einen zur Initiierung der Polymeri- sation geeigneten Initiator und/oder Katalysator enthält, wonach das Mono-, Di- und/oder Oligomer zu dem Matrixpoly- mer polymerisiert wird. In erzeugnistechnischer Hinsicht sieht die Erfindung zur Lösung dieser Aufgabe ferner ein mittels eines solchen Ver- fahrens hergestelltes endlosfaserverstärktes 3D-Druckfila- ment vor, welches wenigstens ein thermoplastisches Matrix- polymer mit einer Mehrzahl an sich vornehmlich in Längs- richtung des 3D-Druckfilamentes erstreckenden Endlosfasern aufweist. Die erfindungsgemäße Ausgestaltung ermöglicht aufgrund der gegenüber dem plastifizierten Matrixpolymer des endlos- faserverstärkten 3D-Druckfilamentes deutlich geringeren Viskosität der zur Imprägnierung der ausgerichteten Endlos- fasern verwendeten Mono-, Di- und/oder Oligomere, welche in situ zu dem Matrixpolymer polymerisiert werden, und der hiermit einhergehenden besseren Kapillarwirkung bei der Im- prägnierung zunächst insoweit eine erheblich verbesserte Qualität des derart erzeugten 3D-Druckfilamentes, als ei- nerseits eine praktisch vollständige Benetzung der Endlos- fasern stattfinden kann und auf diese Weise eine Porenbil- dung zuverlässig vermieden wird, andererseits eine äußerst homogene Faserverteilung in dem 3D-Druckfilament erzeugt wird, welche zu einer hohen Festigkeit und insbesondere Zä- higkeit eines hiermit gedruckten endlosfaserverstärkten Po- lymer-Formteils ohne Fehlstellen führt. In Verbindung mit der in situ Polymerisation der flüssigen Mono-, Di- und/oder Oligomere der flüssigen Reaktionsmischung in Ge- genwart des Initiators und/oder Katalysators zu dem Matrix- polymer des endlosfaserverstärkten 3D-Druckfilamentes ergibt dies ferner eine verbesserte Anhaftung des Matrixpo- lymers an den Endlosfasern, was gleichfalls in einer höhe- ren Festigkeit und Zähigkeit eines hiermit gedruckten end- losfaserverstärkten Polymer-Formteils einhergeht. Im Hin- blick auf eine geringstmögliche Viskosität der flüssigen Reaktionsmischung kann es dabei in vielen Fällen von Vor- teil sein, Monomeren den Vorzug gegenüber Di- und/oder ins- besondere Oligomeren zu geben. Darüber hinaus lässt sich erfindungsgemäß der Faseran- teil in dem 3D-Druckfilament signifikant vergrößern, wobei festgestellt wurde, dass auf diese Weise 3D-Druckfilamente mit einem Anteil an sehr homogen über ihren Querschnitt verteilten Fasern von bis zu etwa 70 Vol.-% bis 80 Vol.-%, bezogen auf das Gesamtvolumen des 3D-Druckfilamentes, mit- tels kommerziell erhältlichen 3D-Druckern verarbeitet wer- den können, wohingegen bislang bekannte 3D-Druckfilamente einen Faseranteil von maximal etwa 40 Vol.-% bis 50 Vol.-% aufweisen. Dies bietet insbesondere Vorteile hinsichtlich einer gewünschten Leichtbauweise solchermaßen gedruckter endlosfaserverstärkter Polymer-Formteile sowie im Hinblick auf deren Zähigkeit in Erstreckungsrichtung der Fasern, welche - wie bereits erwähnt - durch die Bewegungsrichtung des Druckkopfes des 3D-Druckers frei eingestellt werden kann. Überdies macht es die Erfindung aus den obigen Grün- den möglich, den Querschnitt bzw. den Durchmesser des 3D- Druckfilamentes gegenüber dem Stand der Technik in erhebli- cher Weise zu vergrößern, wobei anhand von Experimenten festgestellt worden ist, dass sich z.B. in der erfindungs- gemäßen Weise hergestellte endlosfaserverstärkte 3D-Druck- filamente mit einem Durchmesser von bis zu 15 mm zu einem endlosfaserverstärkten Polymer-Formteil drucken lassen, wo- hingegen bislang verfügbare, mit einer Endlosfaserverstär- kung versehene 3D-Druckfilamente üblicherweise einen Durch- messer zwischen etwa 0,5 mm und etwa 1,75 mm besitzen. In entsprechender Weise können erfindungsgemäß dickere und so- mit nicht nur stabilere, sondern auch kostengünstigere End- losfasern eingesetzt werden als dies bislang möglich war. Ein weiterer Vorteil der Erfindung besteht darin, dass sich die Kristallinität sowie insbesondere die Molmasse des in situ erzeugten Matrixpolymers des endlosfaserverstärkten 3D-Druckfilamentes signifikant vergrößern lässt, wobei eine gegenüber dem Stand der Technik bis zu etwa 50% höhere Kristallinität des Matrixpolymers und eine etwa um das 3 bis 10-fache größere Molmasse von bis zu etwa 1.000.000 g/mol bis 1.200.000 g/mol erreicht werden können. Darüber hinaus wird die Gefahr einer thermischen Beein- trächtigung des Matrixpolymers gegenüber dem Stand der Technik deutlich verringert, da das in situ aus den flüssi- gen Mono-, Di- und/oder Oligomeren polymerisierte Matrixpo- lymer nur ein einziges Mal aufgeschmolzen werden muss, wenn es anlässlich des Schmelzschichtverfahrens mittels eines 3D-Druckers zu einem endlosfaserverstärkten Polymer-Form- teil verarbeitet wird, wohingegen die herkömmliche Schmelz- imprägnierung der Endlosfasern ein mindestens zweimaliges Aufschmelzen des Matrixpolymers erfordert. In diesem Zusam- menhang gewährleistet das erfindungsgemäße Verfahren auch eine gegenüber dem Stand der Technik verbesserte Energie- und somit Kosteneffizienz, da kein bereits fertiges Matrix- polymer plastifiziert und aufgeschmolzen werden muss. Die Einstellbarkeit sowohl des Filamentdurchmessers als auch der Molmasse des Matrixpolymers in sehr breiten Gren- zen bei einer gleichzeitig sehr homogenen Faserverteilung über den Filamentquerschnitt unter Vermeidung von Poren in- folge einer nicht hinreichenden Imprägnierung vermögen dem endlosfaserverstärkten 3D-Druckfilament insbesondere auch während seiner Verarbeitung im Schmelzschichtverfahren mit- tels 3D-Druckern eine sehr hohe Steifigkeit und Zähigkeit zu verleihen, so dass aus der Düse des Druckkopfes von 3D- Druckern ausgetragene Plastifikatstränge des endlosfaser- verstärkten 3D-Druckfilamentes nicht notwendigerweise nur auf bereits gedruckten Schichten eines erzeugten Polymer- Formteils abgeschieden bzw. abgelegt werden müssen. Viel- mehr macht es die Erfindung überraschenderweise möglich, dass ein solcher Plastifikatstrang mittels des 3D-Druckers auch mehr oder minder frei dreidimensional im Raum angeord- net werden kann, wobei er entsprechend der Bewegungsbahn des Druckkopfes "stehenbleibt", ohne infolge Gravitation zu kollabieren und auf eine bereits gedruckte Lage eines Poly- mer-Formteil herabzufallen, so dass entsprechend der pro- grammierten Bewegung des Druckkopfes praktisch beliebige dreidimensionale Gebilde erzeugt werden können, deren Fa- serorientierung durch die Bewegung des Druckkopfes vorgege- ben werden kann. Lediglich beispielhaft seien in diesem Zu- sammenhang Stützstrukturen von Bauteilen in Skelett- oder Wabenbauweise erwähnt. Den eingesetzten Fasertypen sind hierbei ebenso wenig Grenzen gesetzt wie der Querschnittsform des endlosfaser- verstärkten 3D-Druckfilamentes, zu welcher die Endlosfasern vor ihrer Imprägnierung ausgerichtet werden, wobei je nach Anordnung der Endlosfasern vor ihrer Imprägnierung kreis- runde, ovale, drei-, vier-, mehreckige oder andersartige Querschnittsformen des endlosfaserverstärkten 3D-Druck- filamentes erzeugt werden können. Als Endlosfasern kommen beliebige bekannte Fasertypen organischer oder anorgani- scher bzw. mineralischer Natur in Betracht einschließlich Glas-, Kohlenstoff-, Aramid-, Basaltfasern und dergleichen. Bei erfindungsgemäßen endlosfaserverstärkten 3D-Druck- filamenten ist es demnach möglich, dass sie mit einem Fa- servolumenanteil von bis zu etwa 80 Vol.-%, z.B. zwischen etwa 50 Vol.-% und etwa 80 Vol.-%, vorzugsweise zwischen etwa 55 Vol.-% und etwa 80 Vol.-%, zwischen etwa 60 Vol.-% und etwa 80 Vol.-% oder zwischen etwa 65 Vol.-% und etwa 80 Vol.-%, jeweils bezogen auf das Gesamtvolumen des 3D- Druckfilamentes, hergestellt werden; ein erfindungsgemäßes endlosfaserverstärktes 3D-Druckfilament kann demnach vor- zugsweise einen Faservolumenanteil in den vorgenannten An- teilen aufweisen. Alternativ oder zusätzlich können die er- findungsgemäßen endlosfaserverstärkten 3D-Druckfilamente mit einem Durchmesser von bis zu etwa 15 mm, z.B. zwischen etwa 2 mm und etwa 15 mm, vorzugsweise zwischen etwa 3 mm und etwa 15 mm, zwischen etwa 4 mm und etwa 15 mm oder zwi- schen etwa 5 mm und etwa 15 mm, hergestellt werden; ein er- findungsgemäßes endlosfaserverstärktes 3D-Druckfilament kann folglich vorzugsweise einen Durchmesser in den vorge- nannten Abmessungen aufweisen. Darüber hinaus können die erfindungsgemäßen endlosfaserverstärkten 3D-Druckfilamente mit einer Molmasse des thermoplastischen Matrixpolymers von bis zu etwa 1.200.000 g/mol, z.B. zwischen etwa 300.000 g/mol und etwa 1.200.000 g/mol, zwischen etwa 400.000 g/mol und etwa 1.200.000 g/mol, zwischen etwa 500.000 g/mol und etwa 1.200.000 g/mol oder zwischen etwa 600.000 g/mol und etwa 1.200.000 g/mol, hergestellt werden; ein erfindungsgemäßes endlosfaserverstärktes 3D-Druckfila- ment kann somit vorzugsweise eine Molmasse in den vorge- nannten Größen aufweisen. Als Matrixpolymer der erfindungsgemäßen endlosfaserver- stärkten 3D-Druckfilamente kommen grundsätzlich beliebige bekannte thermoplastische Polymere einschließlich Copolyme- ren und deren Blends in Betracht, wie beispielsweise solche aus der Gruppe - der Polyamide, z.B. Guss-Polyamide und/oder anionische Polyamide, wie Polyamid-6 (PA6), Polyamid-12 (PA12) und dergleichen, - der Polyolefine, z.B. Polyethylen, Polypropylen (PP), Polybutylen (PB) und dergleichen, - der thermoplastischen Polyurethane (TPU), und - der thermoplastischen Polyester, z.B. Polymethacrylate, Polyalkylenterephthalate, wie Polyethylen- (PET), Polypropylen- (PPT), Polybutylenterephthalat (PBT) etc., und dergleichen. Die Auswahl der zur Imprägnierung der Endlosfasern einge- setzten flüssigen Mono-, Di- und/oder Oligomere richtet sich hierbei nach dem jeweiligen, in situ zu erzeugenden Matrixpolymer, wobei im Falle der vorgenannten Polyamide beispielsweise Caprolactame, Laurinlactame, Aminocarbonsäu- ren oder Diamine in Verbindung mit Dicarbonsäuren einge- setzt werden können. Im Falle von Polyolefinen können als flüssige Imprägniermonomere beispielsweise Ethylen, Propy- len, Butylen und dergleichen eingesetzt werden, wohingegen im Falle von thermoplastischen Polyurethanen z.B. entspre- chende Diisocyanate in Verbindung mit entsprechenden Diolen eingesetzt werden können. Beispiele von flüssigen Impräg- niermonomeren für thermoplastische Polyester umfassen Me- thacrylsäure, Lactone, Dicarbonsäuren in Verbindung mit Di- olen, wie z.B. Terephthalsäure in Verbindung mit Ethandiol, 1,3-Propandiol, 1,4-Butandiol etc. In vorteilhafter Ausgestaltung des erfindungsgemäßen Verfahrens kann vorgesehen sein, dass wenigstens eine erste flüssige Komponente, welche wenigstens ein flüssiges Mono-, Di- und/oder Oligomer enthält, und wenigstens eine zweite flüssige Komponente, welche den Initiator und/oder Kataly- sator enthält, getrennt auf Vorrat gehalten und unmittelbar vor dem Imprägnieren der Mehrzahl an ausgerichteten Endlos- fasern zu der flüssigen Reaktionsmischung vermischt werden. Selbstverständlich können auch mehr als zwei flüssige Kom- ponenten, aus welchen die Reaktionsmischung gebildet wird, getrennt auf Vorrat gehalten werden, sofern das in situ zu polymerisierende Matrixpolymer des endlosfaserverstärkten 3D-Druckfilamentes z.B. eine Mehrzahl an verschiedenen Mo- no-, Di- und/oder Oligomeren erfordert. Um insbesondere für eine im Wesentlichen kontinuierliche oder semikontinuierliche Herstellung der erfindungsgemäßen endlosfaserverstärkten 3D-Druckfilamente nach Art des als solchen bekannten Pultrusionsverfahrens zu sorgen, kann die Mehrzahl an Endlosfasern vorzugsweise im Wesentlichen kon- tinuierlich von wenigstens einer Spule, insbesondere von einer Mehrzahl an Spulen, abgewickelt werden. Anschließend kann die Mehrzahl an Endlosfasern vor dem Imprägnieren mit der flüssigen Reaktionsmischung vorzugs- weise vorgewärmt und/oder getrocknet werden, um einerseits einen etwaigen Restfeuchtegehalt der Endlosfasern zu elimi- nieren und andererseits die Endlosfasern auf die erforder- liche Temperatur der Polymerisationsreaktion zu bringen. Die Mehrzahl an ausgerichteten Endlosfasern kann sodann vorteilhafterweise in einem Pultrusionswerkzeug mit der flüssigen Reaktionsmischung imprägniert und die flüssige Reaktionsmischung zu dem thermoplastischen Matrixpolymer polymerisiert wird. Zu diesem Zweck können die Endlosfasern insbesondere durch einen Düsenkanal des Pultrusionswerk- zeugs hindurch geführt werden, in welchem sie mit der flüs- sigen Reaktionsmischung imprägniert werden und in welchem letztere in situ zu dem Matrixpolymer polymerisiert wird. Gemäß einer Weiterbildung des erfindungsgemäßen Verfah- rens kann ferner vorgesehen sein, dass auf den aus den mit dem thermoplastischen Matrixpolymer imprägnierten Endlosfa- sern gebildeten Endlosstrang eine Mantelschicht aus wenigs- tens einem weiteren thermoplastischen Polymer aufextrudiert wird, wobei es sich bei dem weiteren thermoplastischen Po- lymer der Mantelschicht insbesondere - um dasselbe Polymer wie das Matrixpolymer, aber mit einer unterschiedlichen, insbesondere geringeren, Molmasse, - um ein anderes, aber mit dem Matrixpolymer verträgli- ches Polymer, und/oder - um ein mit wenigstens einem Additiv versetztes Poly- mer handelt. Das Polymer der Mantelschicht kann dabei zweckmä- ßigerweise nach im Wesentlichen vollständiger Polymerisati- on des Matrixpolymers auf dieses aufextrudiert werden, um dem endlosfaserverstärkten 3D-Druckfilament sowie insbeson- dere auch einem hierdurch mittels des Schmelzschichtverfah- rens erzeugten endlosfaserverstärkten Polymer-Formteil zu- sätzliche Eigenschaften zu verleihen. So kann die Mantel- schicht aus dem weiteren Polymer beispielsweise zur verbes- serten Anhaftung bzw. Verschweißbarkeit eines auf eine be- reits gedruckte Lage eines Polymer-Formteils aufgedruckte weitere Lage aus Plastifikatsträngen des endlosfaserver- stärkten 3D-Druckfilamentes dienen, oder das wenigstens ei- ne Polymer der Mantelschicht kann beispielsweise auch mit Additiven versetzt werden, wie elektrisch leitfähigen und/oder magnetischen Füllstoffen, Farbstoffen, Pigmenten und dergleichen. Bei einem solchermaßen hergestellten endlosfaserver- stärkten 3D-Druckfilament kann demnach vorgesehen sein, dass es eine Mantelschicht aus wenigstens einem weiteren thermoplastischen Polymer aufweist, wobei es sich bei dem weiteren thermoplastischen Polymer der Mantelschicht insbe- sondere - um dasselbe Polymer wie das Matrixpolymer, aber mit einer unterschiedlichen, insbesondere geringeren, Mol- masse, - um ein anderes, aber mit dem Matrixpolymer verträgliches Polymer, und/oder - um ein mit wenigstens einem Additiv versetztes Polymer handelt. Nach dem Imprägnieren der Endlosfasern und Polymerisie- ren der flüssigen Reaktionsmischung zu dem Matrixpolymer kann der aus den mit dem thermoplastischen Matrixpolymer imprägnierten Endlosfasern gebildete Endlosstrang zwecks eines kontinuierlichen oder semikontinuierlichen Vorschubs im Wesentlichen kontinuierlich gefördert wird, indem er insbesondere zwischen gegenläufig drehangetriebenen Walzen oder Bändern hindurch bewegt wird, mit deren Drehgeschwin- digkeit die jeweilige Vorschubgeschwindigkeit gesteuert werden kann. Darüber hinaus kann der aus den mit dem thermoplasti- schen Matrixpolymer imprägnierten Endlosfasern gebildete Endlosstrang schließlich zweckmäßigerweise - auf eine Rolle aufgewickelt und zu aufgewickelten end- losfaserverstärkten 3D-Druckfilamenten abgelängt; oder - zu sich im Wesentlichen geradlinig erstreckenden end- losfaserverstärkten 3D-Druckfilamenten abgelängt werden. Im erstgenannten Fall kann eine im Wesentlichen kontinuierliche Förderung des Endlosstrangs auch mittels eines Antriebs der Rolle geschehen, auf welche das fertige endlosfaserverstärkte 3D-Druckfilament aufgewickelt wird, so dass keine zusätzliche Zugkraft mittels drehangetriebe- nen Walzen oder Bändern vonnöten ist. Weitere Merkmale und Vorteile der Erfindung ergeben sich aus der nachfolgenden Beschreibung von Ausführungsbeispie- len unter Bezugnahme auf die Zeichnungen. Dabei zeigen: Fig. 1 eine schematische Ansicht einer zur Durchführung des erfindungsgemäßen Verfahrens geeigneten Aus- führungsform einer Vorrichtung zur Herstellung von endlosfaserverstärkten 3D-Druckfilamenten; Fig. 2 eine mikroskopische Aufnahme des Querschnittes eines konventionell erzeugten endlosfaserver- stärkten 3D-Druckfilamentes; und Fig. 2 eine mikroskopische Aufnahme des Querschnittes eines mittels des erfindungsgemäßen Verfahrens erzeugten endlosfaserverstärkten 3D-Druckfila- mentes. In der Fig. 1 ist eine schematische Ansicht einer Vor- richtung zur Herstellung von endlosfaserverstärkten 3D- Druckfilamenten schematisch dargestellt, welche zur konti- nuierlichen oder semikontinuierlichen der endlosfaserver- stärkten 3D-Druckfilamente nach Art des Pultrusionsverfah- rens dient. Die Vorrichtung umfasst eine Vorratsstation 1 mit einer Mehrzahl an Spulen 2, auf welchen die zu verar- beitenden Endlosfasern 3 aus beliebigen bekannten Materia- lien aufgewickelt sind. In Förderrichtung der Endlosfasern 3 (in der Fig. 1 von links nach rechts) schließt sich an die Vorratsstation 1 eine Vorwärm- und Trocknungsstation 4 an, durch welche die von den Spulen 2 abgewickelten Endlos- fasern 3 hindurchgeführt werden können. Die Vorwärm- und Trocknungsstation 4 kann bei dem zeichnerisch wiedergegebe- nen Ausführungsbeispiel zugleich zur Ausrichtung der End- losfasern 3 gemäß ihrer vorgesehenen Anordnung in dem zu erzeugenden endlosfaserverstärkten 3D-Druckfilament dienen, um sie z.B. entsprechend dessen gewünschter Querschnitts- form auszurichten. Indes kann zu den vorgenannten Zwecken selbstverständlich alternativ oder zusätzlich zu der Vor- wärm- und Trocknungsstation 4 eine separate Ausrichtstation für die Endlosfasern 3 vorgesehen sein (nicht gezeigt). Wiederum stromab der Vorwärm- und Trocknungsstation 4 befindet sich ein Pultrusionswerkzeug 5, in dessen Düsenka- nal 6 die ausgerichteten Endlosfasern 3 mit einer flüssigen Reaktionsmischung imprägniert werden können, welche einer- seits wenigstens ein zur Polymerisation zu dem thermoplas- tischen Matrixpolymer geeignetes flüssiges Mono-, Di- und/oder Oligomer, andererseits wenigstens einen zur Initi- ierung der Polymerisation geeigneten Initiator und/oder Ka- talysator enthält. Das Pultrusionswerkzeug 5 umfasst zu diesem Zweck einen mit dem Düsenkanal 6 in Verbindung ste- henden Einlasskanal 7, welcher in eine Mischkammer 8 mün- det, welche wiederum mit zwei oder mehreren getrennten Vor- ratsbehältern 9, 10 in Verbindung steht. Letztere dienen zur Bevorratung einzelner Komponenten der flüssigen Reakti- onsmischung, wie beispielsweise einerseits eines oder meh- rere Monomere, andererseits Initiatoren und/oder Katalysa- toren zum Auslösen der Polymerisation. Sofern ein endlosfa- serverstärktes 3D-Druckfilament 17 mit einer Kern-/Mantel- struktur erzeugt werden soll, kann dem Pultrusionswerkzeug 5 beispielsweise ein weiteres Pultrusionswerkzeug (nicht zeichnerisch wiedergegeben) gemäß dem Stand der Technik nachgeordnet sein, welches zum Aufextrudieren eines plasti- fizierten Polymers der Mantelschicht auf den endlosfaser- verstärkten Endlosstrang 14 ausgestaltet ist, welcher aus den mit dem thermoplastischen Matrixpolymer imprägnierten Endlosfasern 3 gebildet ist. Stromab des Pultrusionswerkzeugs 5 schließt sich an die- ses eine Vorschubstation 11 an, welche beispielsweise zwei oder mehrere, entsprechend dem gewünschten Vorschub gesteu- ert angetriebene, umlaufende Bänder 12, 13 aufweist, zwi- schen welchen der von dem aus den nunmehr mit dem thermo- plastischen Matrixpolymer imprägnierten Endlosfasern gebil- dete Endlosstrang 14 hindurch geführt werden kann. Stromab der Vorschubstation 11 befindet sich bei dem zeichnerisch wiedergegebenen Ausführungsbeispiel schließlich eine Wi- ckelstation 15, welche zum Aufwickeln der erzeugten endlos- faserverstärkten 3D-Druckfilamente 17 auf eine Rolle 16 dient, welche ihrerseits entsprechend dem gewünschten Vor- schub gesteuert drehangetrieben sein kann. Zum Ablängen des Endlosstrangs 14, welcher aus den mit dem thermoplastischen Matrixpolymer imprägnierten Endlosfasern 3 gebildet ist, zu den endlosfaserverstärkten 3D-Druckfilamenten dient eine zwischen der Vorschubstation 11 und der Wickelstation 15 angeordnete Schneideinrichtung 18. Anlässlich der Durchführung des erfindungsgemäßen Ver- fahrens zur Herstellung von endlosfaserverstärkten 3D- Druckfilamenten 17 mittels der Vorrichtung gemäß der Fig. 1 wird eine Mehrzahl an Endlosfasern 3 im Wesentlichen konti- nuierlich von den Spulen 2 der Vorratsstation 1 abgewi- ckelt, wobei die Vorschubgeschwindigkeit der Endlosfasern 3 durch die Umlaufgeschwindigkeit der umlaufenden Bänder 12, 13 der Vorschubstation 11 gesteuert werden kann. Die End- losfasern 3 werden an die Vorwärm- und Trocknungsstation 4 überführt, um einerseits eine etwaige Restfeuchte zu ent- fernen und die Endlosfasern 3 auf die Polymerisationstempe- ratur vorzuwärmen und sie andererseits entsprechend ihrer Anordnung in dem 3D-Druckfilament 17, wie insbesondere ent- sprechend der gewünschten Querschnittsform, auszurichten (vgl. die schematische Querschnittsansicht A der im vorlie- genden Fall im Wesentlichen kreisrund ausgerichteten End- losfasern 3 gemäß der Fig. 1). Die ausgerichteten Endlosfasern 3 gelangen sodann in den Düsenkanal 6 des Pultrusionswerkzeugs 5, wo sie mit einer flüssigen Reaktionsmischung imprägniert werden, welche dem Düsenkanal 6 aus der Mischkammer 8 über den Einlasskanal 7 zugeführt wird. Die flüssige Reaktionsmischung ist im vor- liegenden Fall beispielsweise aus zwei in den beiden sepa- raten Vorratsbehältern 9, 10 getrennt voneinander auf Vor- rat gehaltenen Komponenten gebildet, von welchen eine z.B. ein oder mehrere zur Polymerisierung zu dem Matrixpolymer geeignete(s) flüssige(s) Mono-, Di- und/oder Oligomer(e) und die andere z.B. zur Aktivierung der Polymerisierung ge- eignete Initiatoren, Katalysatoren oder dergleichen ent- hält. Die flüssige Reaktionsmischung wird nach der Impräg- nierung der Endlosfasern 3 im Mündungsbereich des Einlass- kanals 8 in den Düsenkanal 7 des Pultrusionswerkzeugs 6 in situ zu dem thermoplastischen Matrixpolymer polymerisiert. Lediglich beispielhaft kann es sich bei einem Monomer der flüssigen Reaktionsmischung beispielsweise um ε-Caprolactam handeln, welches mittels geeigneter Initiatoren, wie bei- spielsweise in Form von Alkoholaten, mittels anionischer Kettenpolymerisation zu Polycaprolactam (Polyamid-6) als Matrixpolymer umgesetzt wird. Die homogene Faserverteilung in dem solchermaßen erzeugten Endlosstrang 14 entspricht weitestgehend jener der ausgerichteten Endlosfasern 3 stromauf des Pultrusionswerkzeug 5 (vgl. die schematische Querschnittsansicht B gemäß der Fig. 1). Sofern ein endlos- faserverstärktes 3D-Druckfilament mit einer Kern-/Mantel- struktur erzeugt werden soll, gilt das oben in Bezug auf die Fig. 1 gesagte. Der derart erzeugte Endlosstrang 14, welcher aus den mit dem thermoplastischen Matrixpolymer imprägnierten Endlosfa- sern 3 gebildet ist, wird anschließend zwischen den umlau- fenden Bändern 11, 12 der Vorschubstation hindurch geführt wird. Stromab der Vorschubstation wird der Endlosstrang 14 schließlich mittels der Schneideinrichtung 18 entsprechend der gewünschten Länge zu den endlosfaserverstärkten 3D- Druckfilamenten 17 abgelängt, welche im vorliegenden Fall zuvor auf die Rolle(n) 16 der Wickelstation 15 aufgewickelt worden sind. Selbstverständlich ist es stattdessen auch möglich, den Endlosstrang 14 zu im Wesentlichen geradlini- gen endlosfaserverstärkten 3D-Druckfilamenten abzulängen (nicht gezeigt), welche anschließend konfektioniert und verpackt werden können. Die Fig. 2 zeigt eine mikroskopische Ansicht des Quer- schnittes eines auf herkömmliche Weise mittels Schmelz- imprägnierung erzeugten endlosfaserverstärkten 3D-Druck- filamentes, wobei einerseits eine sehr inhomogene Vertei- lung der Endlosfasern, andererseits eine Mehrzahl an mit kreisförmigen Umrandungen gekennzeichnete Poren erkennbar sind, welche aufgrund einer bereichsweise nur unvollständi- gen Benetzung mit der flüssig-viskosen Schmelze des plasti- fizierten Matrixpolymers entstanden sind. In der Fig. 3 ist eine mikroskopische Aufnahme des Quer- schnittes eines mittels des erfindungsgemäßen Verfahrens, wie es oben unter Bezugnahme auf die Fig. 1 erläutert ist, erzeugten endlosfaserverstärkten 3D-Druckfilamentes wieder- gegeben, welches selbst bei einem gegenüber der Fig. 1 deutlich größeren Anteil an Fasern eine sehr homogene Fa- serverteilung besitzt und frei von Poren ist. Aufgrund der weiter oben beschriebenen Vorteile besitzen aus einem sol- chen 3D-Druckfilament mittels des Schmelzschichtverfahrens erzeugte endlosfaserverstärkte Polymer-Formteile nicht nur eine erheblich höhere Qualität, insbesondere hinsichtlich ihrer Zähigkeit, Steifigkeit und Festigkeit, sondern er- schließen sich dem endlosfaserverstärkten 3D-Druckfilament auch neue Anwendungsgebiete, wie insbesondere die Möglich- keit zum 3D-Drucken von endlosfaserverstärkten Formteil- strukturen weitestgehend frei dreidimensional im Raum. Continuous fiber-reinforced 3D printing filament and method for its production The invention relates to a method for producing continuous fiber-reinforced 3D printing filaments, which have at least one thermoplastic matrix polymer with a plurality of continuous fibers extending primarily in the longitudinal direction of the 3D printing filament, by a plurality of continuous fibers is aligned according to their arrangement in the 3D printing filament and impregnated with the at least one thermoplastic matrix polymer, after which the endless strand obtained in this way is cut to length to form the continuous fiber-reinforced 3D printing filament. In addition, the invention relates to a continuous fiber-reinforced 3D printing filament produced in this way, which has at least one thermoplastic matrix polymer with a plurality of continuous fibers extending primarily in the longitudinal direction of the 3D printing filament. For the production of polymer molded parts, the melt layer process, also known as “fused deposition modeling” (FDM) or “fused filament fabrication” (FFF), is known, which is used in 3D printers and represents a manufacturing process in which a 3D printing filament made of a thermoplastic polymer or a polymer blend of several thermoplastic polymers is plasticized and deposited in layers using a nozzle usually provided in the print head of the 3D printer in order to produce the polymer molded part ultimately formed from a large number of such layers generate. On the one hand, this enables layer-by-layer production of relatively complex and, for example, conventional thermoplastic processing methods, such as injection molding, extrusion, which is also suitable for prototyping or small series. ren etc., molded parts with more or less complex structures that are impossible or difficult to produce, although the melt layer process is also increasingly being used for the series production of polymer molded parts with relatively complex structures. In the melt layer process using 3D printing, also known as "additive manufacturing", a three-dimensional model of the molded part to be produced is usually created digitally, which can be done in particular using the known methods of Computer Aided Design (CAD). In addition, using suitable software, such as a so-called slicer program (e.g. Cura TM or the like), the three-dimensional model of the molded part to be produced is broken down into a plurality of thin layers, whereupon the plasticized polymer is moved accordingly using the nozzle Print head is deposited layer by layer to build up the molded part layer by layer. Immediately after the polymer plastic, which is discharged more or less in the form of strands or drops from the nozzle of the print head, the solidification process begins, with the deposited plastic solidifying, for example, at ambient temperature or under active cooling. In order to be able to produce continuous fiber-reinforced polymer molded parts using 3D printing, in addition to conventional 3D printing filaments made of thermoplastic polymers, continuous fiber-reinforced 3D printing filaments have recently been used, which are plasticized and using the nozzle of the print head are then deposited in layers to form the polymer molding, not in the form of drops, but rather in the form of strands, so that the individual layers of the polymer molding produced in this way are reinforced with continuous fibers. are provided, the orientation and alignment of which can be controlled by the movement of the print head. The production of such continuous fiber-reinforced 3D printing filaments, which have at least one thermoplastic matrix polymer with a plurality of continuous fibers extending primarily in the longitudinal direction of the 3D printing filament, is carried out by arranging a plurality of continuous fibers in accordance with their arrangement in the 3D printing filament. Printing filament is aligned and impregnated with the at least one thermoplastic matrix polymer, after which the endless strand thus obtained is cooled to solidify the matrix polymer and is cut to length to form the 3D printing filament. Such a method for producing 3D printing filaments intended for additive manufacturing is known, for example, from DE 102018 213 337 A1, in which a hybrid yarn made of different fiber materials is heated, after which it is overmolded with a plasticized matrix material. The latter can in particular be a thermoplastic polymer which is extruded in plasticized form onto the hybrid yarn or the hybrid yarn is overmolded with the plasticized polymer. However, it has been shown that the known process for producing continuous fiber-reinforced 3D printing filaments is associated with a number of disadvantages. After impregnating the continuous fibers with the plasticized, liquid-viscous matrix polymer, on the one hand there is a very inhomogeneous fiber distribution in the 3D printing filament, and on the other hand, pores form due to gas inclusions between the continuous fibers, which are not sufficient during the impregnation process have been wetted with the plasticized matrix polymer. Both lead to inadequate strength and toughness of a continuous fiber filament produced by 3D printing using such 3D printing filaments. reinforced polymer molding. This applies all the more as the thickness and fiber content of the continuous fiber-reinforced 3D printing filament increases, so that there are narrow limits to both its maximum diameter and its fiber content, with conventional, currently available 3D printing filaments having a maximum thickness of around 1.75 mm and a maximum fiber content of around 40% by volume, based on the total volume of the 3D printing filament. In addition, due to the aforementioned deficits, the plastics deposited from the nozzle of the print head of 3D printers using the known continuous fiber-reinforced 3D printing filaments have very little toughness in the plasticized state, so that they are only based on the already printed layers of the produced polymer molding can be deposited or deposited, whereas it is particularly the case with 3D printing of continuous fiber-reinforced 3D printing filaments, which - as mentioned above - can only be deposited in strand form to form the printed polymer molding , in some applications for the production of three-dimensional structures of the polymer molding it would be desirable if the continuous fiber-reinforced plastic could be arranged more or less freely in three dimensions in space using the 3D printer, without it being supported by a base or is supported by an already printed layer of the polymer molding. The invention is therefore based on the object of developing a method for producing continuous fiber-reinforced 3D printing filaments of the type mentioned in a simple and cost-effective manner in such a way that 3D printing filaments are as pore-free as possible while at least largely avoiding the aforementioned disadvantages with a very homogeneous distribution of the continuous fibers across the filament cross-section, the diameter and fiber size of which part increased compared to the state of the art and which in this way can be given greater toughness in the plasticized state. It is also aimed at an endless fiber-reinforced 3D printing filament produced in this way. From a process engineering point of view, this object is achieved according to the invention in a method of the type mentioned at the outset in that the plurality of aligned continuous fibers are impregnated with a liquid reaction mixture which, on the one hand, at least one for polymerization to the at least one thermoplastic matrix polymer suitable liquid mono-, di- and/or oligomer, on the other hand at least one initiator and/or catalyst suitable for initiating the polymerization, after which the mono-, di- and/or oligomer is polymerized to form the matrix polymer. In terms of product technology, the invention further provides a continuous fiber-reinforced 3D printing filament produced by such a method to solve this problem, which comprises at least one thermoplastic matrix polymer with a plurality of continuous fibers extending primarily in the longitudinal direction of the 3D printing filament having. Due to the significantly lower viscosity of the mono-, di- and/or oligomers used to impregnate the aligned continuous fibers, which are polymerized in situ to form the matrix polymer, the embodiment according to the invention allows for a significantly lower viscosity compared to the plasticized matrix polymer of the continuous fiber-reinforced 3D printing filament The resulting better capillary effect during impregnation initially results in a significantly improved quality of the 3D printing filament produced in this way, on the one hand, a practically complete wetting of the endless fibers can take place and in this way pore formation is reliably avoided, on the other hand an extremely homogeneous fiber distribution is generated in the 3D printing filament, which leads to high strength and in particular toughness of a continuous fiber-reinforced polymer molded part printed herewith without defects . In conjunction with the in situ polymerization of the liquid mono-, di- and/or oligomers of the liquid reaction mixture in the presence of the initiator and/or catalyst to form the matrix polymer of the continuous fiber-reinforced 3D printing filament, this also results in improved adhesion of the matrix polymer. lymers on the continuous fibers, which also results in higher strength and toughness of a continuous fiber-reinforced polymer molded part printed with this. With regard to the lowest possible viscosity of the liquid reaction mixture, it can be advantageous in many cases to give preference to monomers over di- and/or in particular oligomers. In addition, according to the invention, the proportion of fibers in the 3D printing filament can be significantly increased, and it has been found that in this way 3D printing filaments can be produced with a proportion of fibers distributed very homogeneously over their cross section of up to approximately 70% to 80% by volume % by volume, based on the total volume of the 3D printing filament, can be processed using commercially available 3D printers, whereas previously known 3D printing filaments have a fiber content of a maximum of around 40% by volume to 50% by volume. exhibit. This offers particular advantages with regard to a desired lightweight construction of endless fiber-reinforced polymer moldings printed in this way and with regard to their toughness in the direction of extension of the fibers, which - as already mentioned - can be freely adjusted by the direction of movement of the print head of the 3D printer can. Furthermore, for the above reasons, the invention makes it possible to significantly increase the cross section or the diameter of the 3D printing filament compared to the prior art, and it has been found on the basis of experiments that, for example, in the invention - Continuous fiber-reinforced 3D printing filaments with a diameter of up to 15 mm, produced in accordance with this method, can be printed into a continuous fiber-reinforced polymer molding, whereas previously available 3D printing filaments provided with continuous fiber reinforcement usually have a diameter between approximately 0 .5 mm and about 1.75 mm. In a corresponding manner, according to the invention, thicker and therefore not only more stable but also more cost-effective continuous fibers can be used than was previously possible. A further advantage of the invention is that the crystallinity and in particular the molecular weight of the matrix polymer produced in situ of the continuous fiber-reinforced 3D printing filament can be significantly increased, with a crystallinity of the matrix polymer that is up to approximately 50% higher than the prior art and an approximately µm 3 to 10 times larger molecular weight of up to about 1,000,000 g/mol to 1,200,000 g/mol can be achieved. In addition, the risk of thermal impairment of the matrix polymer is significantly reduced compared to the prior art, since the matrix polymer polymerized in situ from the liquid mono-, di- and/or oligomers only needs to be melted once, if it is processed into a continuous fiber-reinforced polymer molding using a 3D printer using the melt layer process, whereas the conventional melt impregnation of the continuous fibers requires the matrix polymer to be melted at least twice. In this context, the method according to the invention also ensures an improved energy and therefore cost efficiency compared to the state of the art, since no already finished matrix polymer has to be plasticized and melted. The ability to adjust both the filament diameter and the molecular weight of the matrix polymer within very wide limits while at the same time ensuring a very homogeneous fiber distribution across the filament cross-section while avoiding pores as a result of insufficient impregnation enables the continuous fiber-reinforced 3D printing filament, especially during its processing in the melt layer process to give a very high level of rigidity and toughness using 3D printers, so that plastic strands of the continuous fiber-reinforced 3D printing filament discharged from the nozzle of the print head of 3D printers are not necessarily only deposited on already printed layers of a polymer molding produced. must be filed. Rather, the invention surprisingly makes it possible for such a strand of plastic to be arranged more or less freely in three dimensions in space using the 3D printer, whereby it "stands still" in accordance with the movement path of the print head without collapsing due to gravity to fall onto an already printed layer of a polymer molded part, so that practically any three-dimensional structure can be created in accordance with the programmed movement of the print head, the fiber orientation of which can be specified by the movement of the print head. In this context, supporting structures of components in skeletal or honeycomb construction should only be mentioned as examples. There are no limits to the types of fibers used, nor to the cross-sectional shape of the continuous fiber-reinforced 3D printing filament, into which the continuous fibers are aligned before they are impregnated, depending on the Arrangement of the continuous fibers before their impregnation allows circular, oval, triangular, quadrangular, polygonal or other cross-sectional shapes of the continuous fiber-reinforced 3D printing filament to be produced. Any known fiber types of organic or inorganic or mineral nature can be considered as continuous fibers, including glass, carbon, aramid, basalt fibers and the like. With continuous fiber-reinforced 3D printing filaments according to the invention, it is therefore possible for them to have a fiber volume fraction of up to about 80% by volume, for example between about 50% by volume and about 80% by volume, preferably between about 55% % by volume and about 80% by volume, between about 60% by volume and about 80% by volume or between about 65% by volume and about 80% by volume, in each case based on the total volume of the 3D printing filaments; A continuous fiber-reinforced 3D printing filament according to the invention can therefore preferably have a fiber volume proportion in the aforementioned proportions. Alternatively or additionally, the continuous fiber-reinforced 3D printing filaments according to the invention can have a diameter of up to about 15 mm, for example between about 2 mm and about 15 mm, preferably between about 3 mm and about 15 mm, between about 4 mm and about 15 mm or between about 5 mm and about 15 mm; A continuous fiber-reinforced 3D printing filament according to the invention can therefore preferably have a diameter in the aforementioned dimensions. In addition, the continuous fiber-reinforced 3D printing filaments according to the invention can have a molecular weight of the thermoplastic matrix polymer of up to about 1,200,000 g/mol, for example between about 300,000 g/mol and about 1,200,000 g/mol, between about 400,000 g/mol and about 1,200,000 g/mol, between about 500,000 g/mol and about 1,200,000 g/mol or between about 600,000 g/mol and about 1,200,000 g/mol; A continuous fiber-reinforced 3D printing filament according to the invention can therefore preferably have a molecular weight in the aforementioned sizes. In principle, any known thermoplastic polymers, including copolymers and their blends, such as those from the group of polyamides, for example cast polyamides and/or anionic polyamides, such as polyamide-6, can be considered as the matrix polymer of the continuous fiber-reinforced 3D printing filaments according to the invention (PA6), polyamide-12 (PA12) and the like, - the polyolefins, for example polyethylene, polypropylene (PP), polybutylene (PB) and the like, - the thermoplastic polyurethanes (TPU), and - the thermoplastic polyesters, for example polymethacrylates, polyalkylene terephthalates , such as polyethylene (PET), polypropylene (PPT), polybutylene terephthalate (PBT) etc., and the like. The selection of the liquid mono-, di- and/or oligomers used to impregnate the continuous fibers depends on the respective matrix polymer to be produced in situ, with in the case of the aforementioned polyamides, for example, caprolactams, laurolactams, aminocarboxylic acids or diamines Connection with dicarboxylic acids can be used. In the case of polyolefins, the liquid impregnation monomers that can be used are, for example, ethylene, propylene, butylene and the like, whereas in the case of thermoplastic polyurethanes, for example, corresponding diisocyanates can be used in conjunction with corresponding diols. Examples of liquid waterproofing monomers for thermoplastic polyesters include methacrylic acid, lactones, dicarboxylic acids in combination with di- oils, such as terephthalic acid in combination with ethanediol, 1,3-propanediol, 1,4-butanediol, etc. In an advantageous embodiment of the method according to the invention, it can be provided that at least a first liquid component, which contains at least one liquid mono-, di- and / or contains oligomer, and at least one second liquid component, which contains the initiator and / or catalyst, is kept separately in stock and mixed to form the liquid reaction mixture immediately before the plurality of aligned continuous fibers are impregnated. Of course, more than two liquid components from which the reaction mixture is formed can also be kept separately in stock, provided that the matrix polymer of the continuous fiber-reinforced 3D printing filament to be polymerized in situ contains, for example, a plurality of different mono-, di- and/or or oligomers required. In order in particular to ensure a substantially continuous or semi-continuous production of the continuous fiber-reinforced 3D printing filaments according to the invention in the manner of the pultrusion process known as such, the plurality of continuous fibers can preferably be unwound essentially continuously from at least one spool, in particular from a plurality of spools become. Subsequently, the plurality of continuous fibers can preferably be preheated and/or dried before impregnation with the liquid reaction mixture in order, on the one hand, to eliminate any residual moisture content of the continuous fibers and, on the other hand, to bring the continuous fibers to the required temperature of the polymerization reaction. The plurality of aligned continuous fibers can then advantageously be impregnated with the liquid reaction mixture in a pultrusion tool and the liquid reaction mixture can be formed into the thermoplastic matrix polymer is polymerized. For this purpose, the continuous fibers can in particular be guided through a nozzle channel of the pultrusion tool, in which they are impregnated with the liquid reaction mixture and in which the latter is polymerized in situ to form the matrix polymer. According to a development of the method according to the invention, it can further be provided that a jacket layer made of at least one further thermoplastic polymer is extruded onto the endless strand formed from the continuous fibers impregnated with the thermoplastic matrix polymer, the further thermoplastic polymer being lymer of the jacket layer in particular - the same polymer as the matrix polymer, but with a different, in particular lower, molecular weight, - a different polymer but compatible with the matrix polymer, and / or - a polymer mixed with at least one additive acts. The polymer of the sheath layer can expediently be extruded onto the matrix polymer after essentially complete polymerization in order to give the continuous fiber-reinforced 3D printing filament and in particular also an endless fiber-reinforced polymer molded part thereby produced by means of the melt layer process additional properties to rent. For example, the jacket layer made of the further polymer can serve for improved adhesion or weldability of a further layer made of plastic strands of the continuous fiber-reinforced 3D printing filament printed onto an already printed layer of a polymer molded part, or at least one For example, additives, such as electrically conductive ones, can also be added to the polymer of the jacket layer and/or magnetic fillers, dyes, pigments and the like. In the case of a continuous fiber-reinforced 3D printing filament produced in this way, it can therefore be provided that it has a sheath layer made of at least one further thermoplastic polymer, whereby the further thermoplastic polymer of the sheath layer is in particular - the same polymer as the matrix polymer, but with a different, in particular lower, molecular weight, - a different polymer but compatible with the matrix polymer, and / or - a polymer mixed with at least one additive. After impregnating the continuous fibers and polymerizing the liquid reaction mixture to form the matrix polymer, the endless strand formed from the continuous fibers impregnated with the thermoplastic matrix polymer can be conveyed essentially continuously for the purpose of a continuous or semi-continuous feed, in particular by moving it between rollers or belts driven in opposite rotation with the rotation speed of which the respective feed speed can be controlled. In addition, the endless strand formed from the continuous fibers impregnated with the thermoplastic matrix polymer can ultimately expediently be wound onto a roll and cut to length into wound continuous fiber-reinforced 3D printing filaments; or - cut to length into continuous fiber-reinforced 3D printing filaments that extend essentially in a straight line become. In the first-mentioned case, a substantially continuous conveyance of the endless strand can also take place by means of a drive of the roller onto which the finished endless fiber-reinforced 3D printing filament is wound, so that no additional tensile force using rotationally driven rollers or belts is necessary. Further features and advantages of the invention result from the following description of exemplary embodiments with reference to the drawings. 1 shows a schematic view of an embodiment of a device for producing continuous fiber-reinforced 3D printing filaments that is suitable for carrying out the method according to the invention; 2 shows a microscopic image of the cross section of a conventionally produced continuous fiber-reinforced 3D printing filament; and FIG. 2 shows a microscopic photograph of the cross section of a continuous fiber-reinforced 3D printing filament produced using the method according to the invention. 1 shows a schematic view of a device for producing continuous fiber-reinforced 3D printing filaments, which is used for the continuous or semi-continuous production of the continuous fiber-reinforced 3D printing filaments in the manner of the pultrusion process. The device comprises a supply station 1 with a plurality of spools 2 on which the continuous fibers 3 to be processed made of any known materials are wound. In the conveying direction of the endless fibers 3 (from left to right in FIG. 1), the storage station 1 is followed by a preheating and drying station 4, through which the endless fibers unwound from the spools 2 fibers 3 can be passed through. In the exemplary embodiment shown in the drawing, the preheating and drying station 4 can also serve to align the continuous fibers 3 according to their intended arrangement in the continuous fiber-reinforced 3D printing filament to be produced, for example in order to align them according to its desired cross-sectional shape. However, for the aforementioned purposes, a separate alignment station for the continuous fibers 3 can of course be provided as an alternative or in addition to the preheating and drying station 4 (not shown). Again downstream of the preheating and drying station 4 there is a pultrusion tool 5, in the nozzle channel 6 of which the aligned continuous fibers 3 can be impregnated with a liquid reaction mixture which, on the one hand, contains at least one liquid monomer suitable for polymerization into the thermoplastic matrix polymer. , di- and/or oligomer, on the other hand contains at least one initiator and/or catalyst suitable for initiating the polymerization. For this purpose, the pultrusion tool 5 comprises an inlet channel 7 which is connected to the nozzle channel 6 and which opens into a mixing chamber 8, which in turn is connected to two or more separate storage containers 9, 10. The latter serve to store individual components of the liquid reaction mixture, such as, on the one hand, one or more monomers and, on the other hand, initiators and/or catalysts for triggering the polymerization. If an endless fiber-reinforced 3D printing filament 17 with a core/sheath structure is to be produced, the pultrusion tool 5 can, for example, be followed by a further pultrusion tool (not shown in the drawing) according to the prior art, which is used to extrude a plasticized polymer the jacket layer on the continuous fiber reinforced endless strand 14 is designed, which is formed from the endless fibers 3 impregnated with the thermoplastic matrix polymer. Downstream of the pultrusion tool 5, this is followed by a feed station 11, which has, for example, two or more rotating belts 12, 13 driven in accordance with the desired feed, between which the from which the now with the thermo - Endless strand 14 formed by plastic matrix polymer impregnated endless fibers can be guided through. In the exemplary embodiment shown in the drawing, downstream of the feed station 11 there is finally a winding station 15, which is used to wind the endless fiber-reinforced 3D printing filaments 17 produced onto a roll 16, which in turn can be rotationally driven in a controlled manner in accordance with the desired feed. A cutting device 18 arranged between the feed station 11 and the winding station 15 is used to cut the endless strand 14, which is formed from the endless fibers 3 impregnated with the thermoplastic matrix polymer, into the continuous fiber-reinforced 3D printing filaments. On the occasion of carrying out the method according to the invention for producing 1, a plurality of continuous fibers 3 are unwound essentially continuously from the spools 2 of the supply station 1, with the feed speed of the continuous fibers 3 being determined by the rotational speed of the rotating belts 12, 13 the feed station 11 can be controlled. The continuous fibers 3 are transferred to the preheating and drying station 4 in order, on the one hand, to remove any residual moisture and to preheat the continuous fibers 3 to the polymerization temperature and, on the other hand, to heat them accordingly Arrangement in the 3D printing filament 17, in particular according to the desired cross-sectional shape (cf. the schematic cross-sectional view A of the essentially circularly aligned endless fibers 3 in the present case according to FIG. 1). The aligned continuous fibers 3 then enter the nozzle channel 6 of the pultrusion tool 5, where they are impregnated with a liquid reaction mixture, which is fed to the nozzle channel 6 from the mixing chamber 8 via the inlet channel 7. In the present case, the liquid reaction mixture is formed, for example, from two components stored separately from one another in the two separate storage containers 9, 10, one of which, for example, contains one or more liquid components suitable for polymerization to form the matrix polymer. s) contains mono-, di- and/or oligomer(s) and other initiators, catalysts or the like suitable for activating the polymerization. After the continuous fibers 3 have been impregnated in the mouth region of the inlet channel 8 into the nozzle channel 7 of the pultrusion tool 6, the liquid reaction mixture is polymerized in situ to form the thermoplastic matrix polymer. Just by way of example, a monomer of the liquid reaction mixture can be, for example, ε-caprolactam, which is converted into polycaprolactam (polyamide-6) as a matrix polymer using suitable initiators, such as in the form of alcoholates, by means of anionic chain polymerization. The homogeneous fiber distribution in the endless strand 14 produced in this way largely corresponds to that of the aligned endless fibers 3 upstream of the pultrusion tool 5 (cf. the schematic cross-sectional view B according to FIG. 1). If an endless fiber-reinforced 3D printing filament with a core/sheath structure is to be created, what was said above with regard to FIG. 1 applies. The endless strand 14 produced in this way, which is formed from the endless fibers 3 impregnated with the thermoplastic matrix polymer, is then guided between the rotating belts 11, 12 of the feed station. Downstream of the feed station, the endless strand 14 is finally cut to length by means of the cutting device 18 according to the desired length to form the endless fiber-reinforced 3D printing filaments 17, which in the present case have previously been wound onto the roll(s) 16 of the winding station 15. Of course, it is also possible instead to cut the endless strand 14 to length into essentially straight continuous fiber-reinforced 3D printing filaments (not shown), which can then be assembled and packaged. 2 shows a microscopic view of the cross section of a continuous fiber-reinforced 3D printing filament produced in a conventional manner by means of melt impregnation, whereby on the one hand a very inhomogeneous distribution of the continuous fibers and on the other hand a plurality of pores marked with circular borders can be seen , which arose due to incomplete wetting with the liquid-viscous melt of the plasticized matrix polymer in some areas. 3 shows a microscopic photograph of the cross section of a continuous fiber-reinforced 3D printing filament produced by means of the method according to the invention, as explained above with reference to FIG A significantly larger proportion of fibers has a very homogeneous fiber distribution and is free of pores. Due to the advantages described above, such a Continuous fiber-reinforced polymer molded parts created using a 3D printing filament using the melt layer process not only have a significantly higher quality, especially in terms of their toughness, stiffness and strength, but also open up new areas of application for the continuous fiber-reinforced 3D printing filament, in particular the possibility of 3D printing -Printing of continuous fiber-reinforced molded part structures as freely as possible in three dimensions in space.

Claims

Patentansprüche Verfahren zur Herstellung von endlosf serverstärkten 3D-Druckf ilamenten (17) , welche wenigstens ein thermoplastisches Mat rixpolymer mit einer Mehrzahl an sich vornehmlich in Längsrichtung des 3D-Druckf ilamentesClaims Method for producing endless server-reinforced 3D printing filaments (17), which have at least one thermoplastic matrix polymer with a plurality, primarily in the longitudinal direction of the 3D printing filament
(17) erstreckenden Endlosfasern (3) aufweisen, indem eine Mehrzahl an Endlosfasern (3) entsprechend ihrer Anordnung in dem 3D-Druckf ilament (17) ausgerichtet und mit dem wenigstens einen thermoplastischen Matrixpoly- mer imprägniert wird, wonach der derart erhaltene Endlosstrang (14) zu dem endlosfaserverstärkten 3D-Druck- filament (17) abgelängt wird, dadurch gekennzeichnet, dass die Mehrzahl an ausgerichteten Endlosfasern (3) mit einer flüssigen Reaktionsmischung imprägniert wird, welche einerseits wenigstens ein zur Polymerisation zu dem wenigstens einen thermoplastischen Matrixpolymer geeignetes flüssiges Mono-, Di- und/oder Oligomer, andererseits wenigstens einen zur Initiierung der Polymerisation geeigneten Initiator und/oder Katalysator enthält, wonach das Mono-, Di- und/oder Oligomer zu dem Matrixpolymer polymerisiert wird. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass wenigstens eine erste flüssige Komponente, welche wenigstens ein flüssiges Mono-, Di- und/oder Oligomer enthält, und wenigstens eine zweite flüssige Komponente, welche den Initiator und/oder Katalysator enthält, getrennt auf Vorrat gehalten und unmittelbar vor dem Imprägnieren der Mehrzahl an ausgerichteten Endlosfasern (3) zu der flüssigen Reaktionsmischung vermischt werden . Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Mehrzahl an Endlosfasern (3) im Wesentlichen kontinuierlich von wenigstens einer Spule (2) , insbesondere von einer Mehrzahl an Spulen (2) , abgewickelt wird. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass die Mehrzahl an Endlosfasern (3) vor dem Imprägnieren mit der flüssigen Reaktionsmischung vorgewärmt und/oder getrocknet wird. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass die Mehrzahl an ausgerichteten Endlosfasern (3) in einem Pultrusionswerkzeug (5) mit der flüssigen Reaktionsmischung imprägniert und die flüssige Reaktionsmischung zu dem thermoplastischen Matrixpo- lymer polymerisiert wird. Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass auf den aus den mit dem thermoplastischen Mat rixpolymer imprägnierten Endlosfasern (3) gebildeten Endlosstrang (14) eine Mantelschicht aus wenigstens einem weiteren thermoplastischen Polymer aufextrudiert wird, wobei es sich bei dem weiteren thermoplastischen Polymer der Mantelschicht insbesondere(17) extending endless fibers (3) by aligning a plurality of continuous fibers (3) according to their arrangement in the 3D printing filament (17) and impregnating them with the at least one thermoplastic matrix polymer, after which the endless strand (14) obtained in this way ) is cut to length to form the continuous fiber-reinforced 3D printing filament (17), characterized in that the plurality of aligned continuous fibers (3) is impregnated with a liquid reaction mixture which, on the one hand, contains at least one liquid mono-polymer suitable for polymerization into the at least one thermoplastic matrix polymer. , di- and / or oligomer, on the other hand contains at least one initiator and / or catalyst suitable for initiating the polymerization, after which the mono-, di- and / or oligomer is polymerized to form the matrix polymer. Method according to claim 1, characterized in that at least a first liquid component, which contains at least one liquid mono-, di- and / or oligomer, and at least a second liquid component, which contains the initiator and / or catalyst, are kept separately in stock and mixed into the liquid reaction mixture immediately before impregnating the plurality of aligned continuous fibers (3). become . Method according to claim 1 or 2, characterized in that the plurality of endless fibers (3) is unwound essentially continuously from at least one spool (2), in particular from a plurality of spools (2). Method according to one of claims 1 to 3, characterized in that the plurality of continuous fibers (3) is preheated and/or dried before being impregnated with the liquid reaction mixture. Method according to one of claims 1 to 4, characterized in that the plurality of aligned continuous fibers (3) are impregnated with the liquid reaction mixture in a pultrusion tool (5) and the liquid reaction mixture is polymerized to form the thermoplastic matrix polymer. Method according to one of claims 1 to 5, characterized in that a jacket layer made of at least one further thermoplastic polymer is extruded onto the endless strand (14) formed from the continuous fibers (3) impregnated with the thermoplastic matrix polymer, the further thermoplastic being Polymer of the cladding layer in particular
- um dasselbe Polymer wie das Matrixpolymer, aber mit einer unterschiedlichen, insbesondere geringeren, Molmasse, - the same polymer as the matrix polymer, but with a different, in particular lower, molar mass,
- um ein anderes, aber mit dem Matrixpolymer verträgliches Polymer, und/oder - a different polymer but compatible with the matrix polymer, and/or
- um ein mit wenigstens einem Additiv versetztes Poly- mer handelt . Verfahren nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass der aus den mit dem thermoplastischen Mat rixpolymer imprägnierten Endlosfasern (3) gebildete Endlosstrang (14) im Wesentlichen kontinuierlich gefördert wird, indem er insbesondere zwischen gegenläufig drehangetriebenen Walzen oder Bändern (12, 13) hindurch bewegt wird. Verfahren nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, dass der aus den mit dem thermoplastischen Mat rixpolymer imprägnierten Endlosfasern (3) gebildete Endlosstrang (14) - around a poly-mixed with at least one additive mer acts. Method according to one of claims 1 to 6, characterized in that the endless strand (14) formed from the endless fibers (3) impregnated with the thermoplastic matrix polymer is conveyed essentially continuously, in particular between rollers or belts (12, 13) which rotate in opposite directions ) is moved through. Method according to one of claims 1 to 7, characterized in that the endless strand (14) formed from the endless fibers (3) impregnated with the thermoplastic matrix polymer
- auf eine Rolle (16) aufgewickelt und zu aufgewickelten endlosfaserverstärkten 3D-Druckf ilamenten (17) abgelängt wird; oder - wound onto a roll (16) and cut to length to form wound endless fiber-reinforced 3D printing filaments (17); or
- zu sich im Wesentlichen geradlinig erstreckenden endlosfaserverstärkten 3D-Druckf ilamenten (17) abgelängt wird. Verfahren nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, dass das endlosfaserverstärkte 3D-Druck- filament mit - is cut to length into essentially straight-line extending continuous fiber-reinforced 3D printing filaments (17). Method according to one of claims 1 to 8, characterized in that the continuous fiber-reinforced 3D printing filament with
- einem Faservolumenanteil von bis zu 80 Vol.-% und/oder- a fiber volume fraction of up to 80% by volume and/or
- einem Durchmesser von bis zu 15 mm und/oder - a diameter of up to 15 mm and/or
- einer Molmasse des thermoplastischen Matrixpolymers von bis zu 1.200.000 g/mol hergestellt wird. Verfahren nach einem der Ansprüche 1 bis 9, dadurch gekennzeichnet, dass das Matrixpolymer aus der Gruppe der Polyamide, der Polyolefine, der thermoplastischen Polyurethane und der thermoplastischen Polyester einschließlich der Polymethacrylate und der Polyalkylen- terephthalate gewählt wird. Endlosfaserverstärktes 3D-Druckf ilament (17) , welches wenigstens ein thermoplastisches Matrixpolymer mit einer Mehrzahl an sich vornehmlich in Längsrichtung des 3D-Druckf ilamentes (17) erstreckenden Endlosfasern (3) aufweist, hergestellt mittels eines Verfahrens nach einem der Ansprüche 1 bis 10. Endlosfaserverstärktes 3D-Druckf ilament nach Anspruch 11, dadurch gekennzeichnet, dass es - a molecular weight of the thermoplastic matrix polymer of up to 1,200,000 g/mol is produced. Method according to one of claims 1 to 9, characterized in that the matrix polymer is from the group of Polyamides, polyolefins, thermoplastic polyurethanes and thermoplastic polyesters including polymethacrylates and polyalkylene terephthalates are selected. Continuous fiber-reinforced 3D printing filament (17), which has at least one thermoplastic matrix polymer with a plurality of continuous fibers (3) extending primarily in the longitudinal direction of the 3D printing filament (17), produced by a method according to one of claims 1 to 10. Continuous fiber-reinforced 3D printing filament according to claim 11, characterized in that it
- einen Faservolumenanteil von bis zu 80 Vol.-% und/oder- a fiber volume fraction of up to 80% by volume and/or
- einen Durchmesser von bis zu 15 mm und/oder - a diameter of up to 15 mm and/or
- eine Molmasse des thermoplastischen Matrixpolymers von bis zu 1.200.000 g/mol aufweist . Endlosfaserverstärktes 3D-Druckf ilament nach Anspruch 11 oder 12, dadurch gekennzeichnet, dass es eine Mantelschicht aus wenigstens einem weiteren thermoplastischen Polymer aufweist, wobei es sich bei dem weiteren thermoplastischen Polymer der Mantelschicht insbesondere - has a molecular weight of the thermoplastic matrix polymer of up to 1,200,000 g/mol. Continuous fiber-reinforced 3D printing filament according to claim 11 or 12, characterized in that it has a sheath layer made of at least one further thermoplastic polymer, the further thermoplastic polymer being the sheath layer in particular
- um dasselbe Polymer wie das Matrixpolymer, aber mit einer unterschiedlichen, insbesondere geringeren, Molmasse, - the same polymer as the matrix polymer, but with a different, in particular lower, molar mass,
- um ein anderes, aber mit dem Matrixpolymer verträgliches Polymer, und/oder - a different polymer but compatible with the matrix polymer, and/or
- um ein mit wenigstens einem Additiv versetztes Polymer handelt . Endlosfaserverstärktes 3D-Druckf ilament nach einem der Ansprüche 11 bis 13 , dadurch gekennzeichnet , dass das Mat rixpolymer aus der Gruppe der Polyamide, der Polyolefine, der thermoplastischen Polyurethane und der thermoplastischen Polyester einschließlich der Poly- methacrylate und der Polyalkylenterephthalate gewählt ist . - a polymer mixed with at least one additive acts. Continuous fiber-reinforced 3D printing filament according to one of claims 11 to 13, characterized in that the matrix polymer is selected from the group of polyamides, polyolefins, thermoplastic polyurethanes and thermoplastic polyesters including polymethacrylates and polyalkylene terephthalates.
PCT/EP2023/063586 2022-06-21 2023-05-22 Endless-fibre-reinforced 3d-printing filament and method for the production thereof WO2023247121A1 (en)

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