WO2017212190A1 - Filament for 3d printing, method for producing such a filament, and method for producing an object using 3d printing - Google Patents

Filament for 3d printing, method for producing such a filament, and method for producing an object using 3d printing Download PDF

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Publication number
WO2017212190A1
WO2017212190A1 PCT/FR2017/051468 FR2017051468W WO2017212190A1 WO 2017212190 A1 WO2017212190 A1 WO 2017212190A1 FR 2017051468 W FR2017051468 W FR 2017051468W WO 2017212190 A1 WO2017212190 A1 WO 2017212190A1
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WO
WIPO (PCT)
Prior art keywords
filament
core
envelope
printing
polyamide
Prior art date
Application number
PCT/FR2017/051468
Other languages
French (fr)
Inventor
Perrine LEGRAND
Original Assignee
Corextrusion Group
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Corextrusion Group filed Critical Corextrusion Group
Publication of WO2017212190A1 publication Critical patent/WO2017212190A1/en

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Classifications

    • 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
    • B33Y70/00—Materials specially adapted for additive manufacturing
    • B33Y70/10—Composites of different types of material, e.g. mixtures of ceramics and polymers or mixtures of metals and biomaterials
    • 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
    • D01D5/253—Formation of filaments, threads, or the like with a non-circular cross section; Spinnerette packs therefor
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F1/00—General methods for the manufacture of artificial filaments or the like
    • D01F1/02—Addition of substances to the spinning solution or to the melt
    • D01F1/10—Other agents for modifying properties
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
    • D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers
    • D01F8/12—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers with at least one polyamide as constituent

Definitions

  • the present invention relates to a filament for 3D printing, a method of manufacturing such a filament, and a method of manufacturing an object by 3D printing using such a filament.
  • 3D printing is understood to mean a process in which a filament of a thermoplastic material is driven through a supply tube to a printing head comprising heating means for heating the filament in a localized way. melts it, and then extrudes the molten material through a nozzle located downstream of the heating means in the path of the filament. The molten material is deposited on a support, in the form of successive superimposed layers.
  • ABS acrylonitrile butadiene styrene
  • PLA polylactic acid
  • filler intended to modify the mechanical properties of the final object.
  • These fillers may be in the form of powders, cut fibers or continuous or discontinuous fibers.
  • An object of the invention is therefore to design a filament for 3D printing that allows to overcome the aforementioned problems, while allowing the obtaining of objects with varied mechanical properties, adapted to the intended use for the object .
  • a filament for 3D printing characterized in that it has a core having a first composition and an envelope surrounding the core having a second composition different from that of the soul, the soul and the envelope each comprising a thermoplastic material, the thermoplastic material of the envelope being miscible with that of the core.
  • the filament has a section whose shape is that of a regular polygon.
  • said section may be star-shaped.
  • the filament may have a section whose shape is substantially that of a regular polygon, with at least one side and / or a rounded apex.
  • the core comprises a filler in the form of fibers or a powder and the envelope is devoid of a load.
  • the core load comprises glass, carbon, poly (p-phenylene-2,6-benzobisoxazole) (PBO) and / or aramid fibers.
  • the fibers are chopped or ground fibers having a diameter of between 18 and 70 ⁇ and a length of between 50 and 500 ⁇ .
  • the charge of the core comprises a powder of thermally conductive particles.
  • the thermally conductive particles comprise metal particles.
  • the core comprises polyamide and the envelope is made of a material impermeable to moisture and / or having a moisture recovery rate lower than that of the polyamide of the core.
  • the core comprises PA6, PA6 / 66 or PA6 / 66/12.
  • the material of the envelope preferably comprises polyamide 12, polyamide
  • the envelope has a thickness of between 0.05 and 0.30 mm, preferably between 0.05 and 0.20 mm.
  • the diameter of the filament is typically between 1 and 3 mm.
  • Another object relates to a process for manufacturing the filament described above.
  • the envelope is formed around the core by coextrusion.
  • the invention also relates to a method of manufacturing an object by 3D printing, in which a filament as described above is used.
  • the invention also relates to a method for limiting the withdrawal of a manufactured object by 3D printing by means of a load contained in a filament, in which a filament as described above is provided, in which the core comprises a charge in the form of fibers or a powder and the casing is free of a load, said filament is driven to a printing head in which said filament is locally heated, and the molten filament is extruded through a nozzle of a 3D printer so as to form the object by superposition of successive layers, the envelope preserving the components of the 3D printer wear by the load of the soul.
  • the invention also relates to a method for controlling the softening of a filament comprising a charge of thermally conductive fibers during the manufacture of an object by 3D printing, in which a filament as described above is provided, wherein the core load comprises a powder of thermally conductive particles, in particular metal particles, said filament is driven to a printing head in which said filament is heated locally, and the molten filament is extruded through a nozzle of a printer 3D so as to form the object by superposition of successive layers, the envelope forming a thermally insulating barrier limiting the softening of the filament upstream of the area of the print head where it is heated.
  • the invention finally relates to a method for preventing the formation of bubbles during the manufacture of an object by 3D printing with a filament comprising polyamide, in which a filament as described above is used, in which the envelope is made of a material impermeable to moisture and / or having a moisture recovery rate lower than that of the polyamide of the core, the envelope thereby forming a barrier to moisture absorption by the filament.
  • FIG. 1 is a block diagram of a 3D printer
  • FIG. 2 is a view of a filament according to one embodiment of the invention
  • Figure 3 shows sectional views of a filament according to different embodiments of the invention.
  • FIG. 1 is a block diagram of a 3D printer. The structure of such a printer is known in itself, only the components useful for understanding the invention are described here.
  • the printer 100 is powered by a coil of a filament 1.
  • Said filament 1 is introduced into the printer then driven and guided to a printing head 101 which comprises, from upstream to downstream on the path of the filament, a so-called “cold” zone 1010, a so-called “hot” zone 101 1 comprising means for heating the filament adapted to melt locally, and a nozzle 1012 through which the molten material is extruded.
  • a printing head 101 which comprises, from upstream to downstream on the path of the filament, a so-called “cold” zone 1010, a so-called “hot” zone 101 1 comprising means for heating the filament adapted to melt locally, and a nozzle 1012 through which the molten material is extruded.
  • a support 200 is placed facing the nozzle 1012 to receive the molten material and support the object during its manufacture by stacking layers.
  • the cold zone 1010 is maintained at a temperature substantially lower than that of the hot zone so as not to cause melting of the filament in said zone 1010. Indeed, a melting or even a significant softening of the filament would cause clogging of the head.
  • the cold zone may comprise cooling means.
  • the filament On its way to the head 101, the filament is driven by drive means 102 such as rollers for example. Before entering the head 101, the filament is guided in a tube 103.
  • composition we mean all the constituents of the soul and the envelope. These constituents include:
  • thermoplastic material or a mixture of thermoplastic materials forming a matrix having a melting point which is suitable for melting in a print head of a 3D printer and then extruding through a nozzle at the exit of the head, and
  • a charge in the form of particles (beads, fibers, etc.) and / or additives (for example: compatibilizing agents, softeners, colorants, etc.) for adjusting the properties of the composition.
  • the core and shell have thermoplastic materials that are miscible with each other, so that although the shell forms a separate layer of the core when the filament is introduced into the 3D printer, the material of the manufactured object is an intimate mixture of said materials.
  • compositions of the core and the shell may differ in the nature of their constituents and / or in the proportion of each constituent.
  • Figure 2 illustrates a filament according to one embodiment of the invention.
  • the filament has a circular section, but the invention is not limited to a particular geometry.
  • the filament is not circular, consider the diameter of a circular filament whose section has an identical area.
  • the diameter of the filament is typically between 1 and 3 mm, the most prevalent diameters at present for the 3D printing filaments being 1.75 mm, 2.85 mm and 3 mm. However, these values are not limiting and may evolve according to the needs of the market.
  • the manufacture of the filament comprises the formation of the core by extrusion through a suitable die.
  • the envelope may be formed by extrusion at the same time as the core (coextrusion) or by another recovery technique implemented during the manufacture of the core or later, in recovery.
  • the coextrusion process is preferred in that it provides the core and shell in a single operation.
  • the manufacturing process is configured to ensure a very precise tolerance on the diameter of the filament, of the order of a hundredth of a millimeter.
  • brushcutter cutting lines which typically have a diameter of the same order of magnitude as the 3D printing filaments described in this text, are not suitable for 3D printing.
  • the drive mechanism of the filament in the printer requires a very high dimensional accuracy of the filament, the tolerance on the diameter of the filament being, as indicated above, of the order of a hundredth of a millimeter.
  • Cutting lines for brush cutters do not require such dimensional accuracy and have a tolerance on the diameter of the order of a tenth of a millimeter.
  • the envelope January 1 forms a layer completely surrounding the core 10 and has a substantially constant thickness over the entire periphery of the core and over the length of the filament.
  • the thickness of the envelope is preferably as thin as possible to fulfill a barrier function (examples of which are described below), without significantly affecting the properties of the object obtained by 3D printing.
  • the material of the envelope forms a small proportion of the material of the object formed by 3D printing, which consists of an intimate mixture of the materials of the core and the envelope.
  • the thickness of the envelope is advantageously between 0.05 mm and 0.20 mm; for a filament of 2.85 or 3 mm in diameter, the thickness of the envelope may be between 0.05 mm and 0.30 mm.
  • the core comprises a filler in the form of particles such as fibers or a powder.
  • PBO poly (p-phenylene-2,6-benzobisoxazole) (PBO), marketed under the name ZYLON TM, which is used in many products requiring high mechanical strength and good thermal stability,
  • Said fillers may be in the form of powder or cut fibers. Optionally, it may also be continuous fibers.
  • the diameter of the fibers is typically between 18 and 70 ⁇ .
  • the length of the fibers may range from 50 ⁇ to 100 ⁇ , or up to 500 ⁇ , long fibers having the effect of binding the object produced by 3D printing from such a filament.
  • said charges may have for one or more of the following effects:
  • a high proportion of metal charges in the core makes it possible to give the object a metallic appearance, to increase its density and to increase its thermal and / or electrical conductivity.
  • a filler such as glass fibers makes it possible to block the shrinkage of the object and to increase its mechanical strength.
  • the envelope is devoid of charges.
  • the envelope has no abrasiveness likely to damage the components of the 3D printer.
  • a filament consisting solely of a thermoplastic material filled with glass fibers and, on the other hand, a filament according to the invention, comprising a core made of a thermoplastic material loaded with glass fibers and an envelope made of an unfilled thermoplastic material and miscible with the material of the core.
  • the 3D printer clogged in a few minutes and disassembly of the printer showed a net wear of the filament drive rollers.
  • the printer could be used for several hours without showing signs of wear.
  • the envelope may advantageously be made of a material forming a barrier to moisture.
  • the envelope prevents the penetration of water within the filament and thus limits the dimensional variations of the filament.
  • the core may comprise PA 6/66/12, which has a moisture recovery rate of 4.5% in an atmosphere at 20 ° C having a moisture content of 50%.
  • the core may comprise PA6 / 66 or PA6, which also have a high rate of moisture recovery.
  • the envelope is advantageously made of PA12, PA10 or PA1010, which have a moisture recovery rate lower than that of PA6, PA6 / 66 or PA6 / 66/12.
  • the PA12 has a relatively low rate of moisture uptake (of the order of 0.8%) and has the advantage of adhering perfectly to the material of the core (in particular as regards PA6 / 66 / 12).
  • the PA10 has an even lower moisture recovery rate (of the order of 0.4%).
  • any impervious material and / or having a low rate of moisture uptake may be used to form the envelope, provided that it has sufficient adhesion to the core material (which is not limited to polyamide). This prevents the formation of bubbles in the core during the heating of the filament.
  • the envelope may also form a thermal barrier to prevent excessive softening of a filament whose core would include a thermally conductive filler, typically comprising one or more metals. Said envelope being devoid of such a load, it provides a thermal insulation of the core which avoids the clogging problem mentioned in the preamble.
  • the envelope can fulfill all or part of the various functions mentioned above.
  • Figure 3 illustrates various non-circular shapes that can take the section of the filament.
  • the thickness of the casing 1 1 is substantially constant over the entire periphery of the filament, the shape of the core 10 is substantially identical to that of the section of the complete filament.
  • non-circular filaments have an increased perimeter relative to the perimeter of a circle to equivalent area have particular advantages.
  • such a non-circular filament has a heating surface in the print head greater than that of a round filament. Consequently, with a cross section or equal mass, the heating time of this filament is shorter, and in particular a fusion is obtained more rapidly in the center of the core of the filament.
  • the filament has a regular polygonal shape, that is to say that its section has at least one axis of symmetry, with sides and equal angles.
  • the polygon may be concave or convex.
  • the polygon advantageously fits in a circle.
  • a particularly preferred example is a star-shaped polygon filament comprising from three to eight vertices, preferably from five to eight vertices.
  • the filament has a regular hexagonal section.
  • the filament may have a "rounded" polygonal shape, that is to say with at least one non-straight side and / or a non-pointed top.

Abstract

The invention relates to a filament (1) for 3D printing, characterised in that it comprises a core (10) having a first composition and a casing (11) surrounding the core (10) and having a second composition different from that of the core (10), the core and the casing each comprising a thermoplastic material, and the thermoplastic material of the casing being miscible with that of the core.

Description

FILAMENT POUR IMPRESSION 3D, PROCEDE DE FABRICATION D'UN TEL FILAMENT, ET PROCEDE DE FABRICATION D'UN OBJET PAR IMPRESSION 3D  FILAMENT FOR 3D PRINTING, METHOD FOR MANUFACTURING SUCH FILAMENT, AND METHOD FOR MANUFACTURING OBJECT BY 3D PRINTING
DOMAINE DE L'INVENTION FIELD OF THE INVENTION
La présente invention concerne un filament pour impression 3D, un procédé de fabrication d'un tel filament, et un procédé de fabrication d'un objet par impression 3D utilisant un tel filament.  The present invention relates to a filament for 3D printing, a method of manufacturing such a filament, and a method of manufacturing an object by 3D printing using such a filament.
ARRIERE PLAN DE L'INVENTION BACKGROUND OF THE INVENTION
La fabrication d'objets par impression 3D prend une ampleur de plus en plus grande, non seulement à des fins de prototypage mais pour des productions à l'échelle industrielle.  The manufacture of objects by 3D printing is becoming increasingly important, not only for prototyping but for industrial scale production.
Par impression 3D, on entend un procédé dans lequel on entraîne un filament d'un matériau thermoplastique au travers d'un tube d'alimentation jusqu'à une tête d'impression comprenant des moyens de chauffage permettant de chauffer le filament de manière localisée de sorte à le fondre, puis on extrude le matériau fondu au travers d'une buse située en aval des moyens de chauffage sur le trajet du filament. Le matériau fondu est déposé sur un support, sous la forme de couches successives superposées.  3D printing is understood to mean a process in which a filament of a thermoplastic material is driven through a supply tube to a printing head comprising heating means for heating the filament in a localized way. melts it, and then extrudes the molten material through a nozzle located downstream of the heating means in the path of the filament. The molten material is deposited on a support, in the form of successive superimposed layers.
Les premiers objets ont été fabriqués avec des filaments d'ABS (acrylonitrile butadiène styrène) ou de PLA (acide polylactique), dans la mesure où ce matériau se prête facilement à l'impression 3D. Toutefois, l'ABS ne confère pas à l'objet de propriétés mécaniques intéressantes ; de plus, sa fusion génère des vapeurs toxiques. Par ailleurs, le PLA, qui présente d'être l'avantage d'être un matériau biosourcé, procure des propriétés mécaniques très faibles et se dégrade en vieillissant.  The first objects were made with ABS (acrylonitrile butadiene styrene) or PLA (polylactic acid) filaments, since this material is easily suitable for 3D printing. However, ABS does not give the object interesting mechanical properties; moreover, its fusion generates toxic vapors. Moreover, PLA, which has the advantage of being a biobased material, provides very low mechanical properties and degrades as it ages.
Le besoin est donc apparu de fabriquer des objets par impression 3D présentant des propriétés mécaniques aussi proches que possibles de celles obtenues avec des procédés de fabrication traditionnels tels que l'injection des matériaux thermoplastiques, par exemple.  The need has therefore appeared to manufacture objects by 3D printing having mechanical properties as close as possible to those obtained with traditional manufacturing processes such as the injection of thermoplastic materials, for example.
A cet effet, des tentatives ont été effectuées pour incorporer au matériau une charge destinée à modifier les propriétés mécaniques de l'objet finales. Ces charges peuvent se présenter sous la forme de poudres, de fibres coupées ou de fibres continues ou discontinues.  For this purpose, attempts have been made to incorporate into the material a filler intended to modify the mechanical properties of the final object. These fillers may be in the form of powders, cut fibers or continuous or discontinuous fibers.
Toutefois, la présence de ces charges dans le filament pose des problèmes dans la mise en œuvre du procédé d'impression 3D.  However, the presence of these charges in the filament poses problems in the implementation of the 3D printing process.
Ainsi, par exemple, dans le cas d'une charge constituée de fibres de verre, qui sont abrasives, il a été constaté que les composants de l'imprimante 3D en contact avec le filament (galets d'entraînement, tube d'alimentation, etc.) s'usent rapidement. Selon un autre exemple, dans le cas d'une charge constituée de particules métalliques, qui sont thermiquement conductrices, il a été constaté que, dans la tête d'impression, le filament est fondu sous l'action des moyens de chauffage mais que, par un effet de conduction thermique par les fibres métalliques, une partie du filament située en amont de la zone fondue s'échauffe également, se ramollit et colle aux parois du tube d'alimentation, bouchant ainsi ledit tube. Thus, for example, in the case of a load consisting of glass fibers, which are abrasive, it has been found that the components of the 3D printer in contact with the filament (drive rollers, feed tube, etc.) wear out quickly. According to another example, in the case of a charge consisting of metal particles, which are thermally conductive, it has been found that, in the print head, the filament is melted under the action of the heating means but that, by a thermal conduction effect by the metal fibers, a portion of the filament located upstream of the melted zone also heats, softens and sticks to the walls of the feed tube, thereby plugging said tube.
Un autre problème se posant avec l'utilisation de matériaux techniques tels que le polyamide est que, comme ce matériau est sujet à une importante reprise d'humidité, le filament absorbe une quantité d'eau importante avant son utilisation. Lorsque le matériau est chauffé dans la tête d'impression, l'eau absorbée se transforme en vapeur et des bulles se créent lors de l'impression, générant ainsi des défauts de l'objet.  Another problem with the use of technical materials such as polyamide is that since this material is subject to a significant moisture uptake, the filament absorbs a significant amount of water prior to use. When the material is heated in the print head, the absorbed water turns into vapor and bubbles are created during printing, thus generating defects in the object.
BREVE DESCRIPTION DE L'INVENTION BRIEF DESCRIPTION OF THE INVENTION
Un but de l'invention est donc de concevoir un filament pour impression 3D qui permette de s'affranchir des problèmes précités, tout en permettant l'obtention d'objets présentant des propriétés mécaniques variées, adaptées à l'usage prévu pour l'objet.  An object of the invention is therefore to design a filament for 3D printing that allows to overcome the aforementioned problems, while allowing the obtaining of objects with varied mechanical properties, adapted to the intended use for the object .
Conformément à l'invention, il est proposé un filament pour impression 3D, caractérisé en ce qu'il présente une âme présentant une première composition et une enveloppe entourant l'âme présentant une seconde composition différente de celle de l'âme, l'âme et l'enveloppe comprenant chacune un matériau thermoplastique, le matériau thermoplastique de l'enveloppe étant miscible avec celui de l'âme.  According to the invention, there is provided a filament for 3D printing, characterized in that it has a core having a first composition and an envelope surrounding the core having a second composition different from that of the soul, the soul and the envelope each comprising a thermoplastic material, the thermoplastic material of the envelope being miscible with that of the core.
Selon un mode de réalisation, le filament présente une section dont la forme est celle d'un polygone régulier.  According to one embodiment, the filament has a section whose shape is that of a regular polygon.
Par exemple, ladite section peut être en forme d'étoile.  For example, said section may be star-shaped.
De manière alternative, le filament peut présenter une section dont la forme est sensiblement celle d'un polygone régulier, avec au moins un côté et/ou un sommet arrondi.  Alternatively, the filament may have a section whose shape is substantially that of a regular polygon, with at least one side and / or a rounded apex.
Selon une forme d'exécution, l'âme comprend une charge sous la forme de fibres ou d'une poudre et l'enveloppe est dépourvue d'une charge.  According to one embodiment, the core comprises a filler in the form of fibers or a powder and the envelope is devoid of a load.
Selon un mode de réalisation, la charge de l'âme comprend des fibres de verre, de carbone, de poly(p-phénylène-2,6-benzobisoxazole) (PBO) et/ou d'aramide.  According to one embodiment, the core load comprises glass, carbon, poly (p-phenylene-2,6-benzobisoxazole) (PBO) and / or aramid fibers.
De manière avantageuse, les fibres sont des fibres coupées ou broyées présentant un diamètre compris entre 18 et 70 μηη et une longueur comprise entre 50 et 500 μηη.  Advantageously, the fibers are chopped or ground fibers having a diameter of between 18 and 70 μηη and a length of between 50 and 500 μηη.
Selon un mode de réalisation, la charge de l'âme comprend une poudre de particules thermiquement conductrices.  According to one embodiment, the charge of the core comprises a powder of thermally conductive particles.
De manière avantageuse, les particules thermiquement conductrices comprennent des particules métalliques. Selon une forme d'exécution, l'âme comprend du polyamide et l'enveloppe est réalisée en un matériau imperméable à l'humidité et/ou présentant un taux de reprise d'humidité inférieur à celui du polyamide de l'âme. Advantageously, the thermally conductive particles comprise metal particles. According to one embodiment, the core comprises polyamide and the envelope is made of a material impermeable to moisture and / or having a moisture recovery rate lower than that of the polyamide of the core.
De manière avantageuse, l'âme comprend du PA6, du PA6/66 ou du PA6/66/12. Le matériau de l'enveloppe comprend de préférence du polyamide 12, du polyamide Advantageously, the core comprises PA6, PA6 / 66 or PA6 / 66/12. The material of the envelope preferably comprises polyamide 12, polyamide
10 ou du polyamide 1010. 10 or polyamide 1010.
De préférence, lequel l'enveloppe présente une épaisseur comprise entre 0,05 et 0,30 mm, de préférence entre 0,05 et 0,20 mm.  Preferably, the envelope has a thickness of between 0.05 and 0.30 mm, preferably between 0.05 and 0.20 mm.
Le diamètre du filament est typiquement compris entre 1 et 3 mm.  The diameter of the filament is typically between 1 and 3 mm.
Un autre objet concerne un procédé de fabrication du filament décrit ci-dessus. Another object relates to a process for manufacturing the filament described above.
Selon ledit procédé, l'enveloppe est formée autour de l'âme par coextrusion. According to said method, the envelope is formed around the core by coextrusion.
L'invention concerne également un procédé de fabrication d'objet par impression 3D, dans lequel on utilise un filament tel que décrit ci-dessus.  The invention also relates to a method of manufacturing an object by 3D printing, in which a filament as described above is used.
L'invention concerne également un procédé pour limiter le retrait d'un objet fabriqué par impression 3D au moyen d'une charge contenue dans un filament, dans lequel on fournit un filament tel que décrit ci-dessus, dans lequel l'âme comprend une charge sous la forme de fibres ou d'une poudre et l'enveloppe est dépourvue d'une charge, on entraîne ledit filament vers une tête d'impression dans lequel ledit filament est chauffé localement, et on extrude le filament fondu au travers d'une buse d'une imprimante 3D de sorte à former l'objet par superposition de couches successives, l'enveloppe préservant les composants de l'imprimante 3D d'une usure par la charge de l'âme.  The invention also relates to a method for limiting the withdrawal of a manufactured object by 3D printing by means of a load contained in a filament, in which a filament as described above is provided, in which the core comprises a charge in the form of fibers or a powder and the casing is free of a load, said filament is driven to a printing head in which said filament is locally heated, and the molten filament is extruded through a nozzle of a 3D printer so as to form the object by superposition of successive layers, the envelope preserving the components of the 3D printer wear by the load of the soul.
L'invention concerne également un procédé pour contrôler le ramollissement d'un filament comprenant une charge de fibres thermiquement conductrices lors de la fabrication d'un objet par impression 3D, dans lequel on fournit un filament tel que décrit ci-dessus, dans lequel la charge de l'âme comprend une poudre de particules thermiquement conductrices, notamment métalliques, on entraîne ledit filament vers une tête d'impression dans lequel ledit filament est chauffé localement, et on extrude le filament fondu au travers d'une buse d'une imprimante 3D de sorte à former l'objet par superposition de couches successives, l'enveloppe formant une barrière thermiquement isolante limitant le ramollissement du filament en amont de la zone de la tête d'impression où il est chauffé.  The invention also relates to a method for controlling the softening of a filament comprising a charge of thermally conductive fibers during the manufacture of an object by 3D printing, in which a filament as described above is provided, wherein the core load comprises a powder of thermally conductive particles, in particular metal particles, said filament is driven to a printing head in which said filament is heated locally, and the molten filament is extruded through a nozzle of a printer 3D so as to form the object by superposition of successive layers, the envelope forming a thermally insulating barrier limiting the softening of the filament upstream of the area of the print head where it is heated.
L'invention concerne enfin un procédé pour éviter la formation de bulles lors de la fabrication d'un objet par impression 3D avec un filament comprenant du polyamide, dans lequel on utilise un filament tel que décrit ci-dessus, dans lequel l'enveloppe est réalisée en un matériau imperméable à l'humidité et/ou présentant un taux de reprise d'humidité inférieur à celui du polyamide de l'âme, l'enveloppe formant ainsi une barrière à la reprise d'humidité par le filament. BREVE DESCRIPTION DES DESSINS The invention finally relates to a method for preventing the formation of bubbles during the manufacture of an object by 3D printing with a filament comprising polyamide, in which a filament as described above is used, in which the envelope is made of a material impermeable to moisture and / or having a moisture recovery rate lower than that of the polyamide of the core, the envelope thereby forming a barrier to moisture absorption by the filament. BRIEF DESCRIPTION OF THE DRAWINGS
D'autres caractéristiques et avantages de l'invention ressortiront de la description détaillée qui va suivre, en référence aux dessins annexés sur lesquels :  Other characteristics and advantages of the invention will emerge from the detailed description which follows, with reference to the appended drawings in which:
la figure 1 est un schéma de principe d'une imprimante 3D,  FIG. 1 is a block diagram of a 3D printer,
- la figure 2 est une vue d'un filament selon un mode de réalisation de l'invention, la figure 3 présente des vues en coupe d'un filament selon différentes formes d'exécution de l'invention.  - Figure 2 is a view of a filament according to one embodiment of the invention, Figure 3 shows sectional views of a filament according to different embodiments of the invention.
Pour des raisons de lisibilité des figures, les différents éléments ne sont pas nécessairement représentés à l'échelle.  For reasons of legibility of the figures, the different elements are not necessarily represented on the scale.
DESCRIPTION DETAILLEE DE L'INVENTION DETAILED DESCRIPTION OF THE INVENTION
La figure 1 est un schéma de principe d'une imprimante 3D. La structure d'une telle imprimante étant connue en elle-même, seuls les composants utiles à la compréhension de l'invention sont décrits ici.  Figure 1 is a block diagram of a 3D printer. The structure of such a printer is known in itself, only the components useful for understanding the invention are described here.
L'imprimante 100 est alimentée par une bobine d'un filament 1 .  The printer 100 is powered by a coil of a filament 1.
Ledit filament 1 est introduit dans l'imprimante puis entraîné et guidé vers une tête d'impression 101 qui comprend, de l'amont vers l'aval sur la trajectoire du filament, une zone dite « froide » 1010, une zone dite « chaude » 101 1 comprenant des moyens de chauffage du filament adaptés pour le faire fondre localement, et une buse 1012 au travers de laquelle le matériau fondu est extrudé.  Said filament 1 is introduced into the printer then driven and guided to a printing head 101 which comprises, from upstream to downstream on the path of the filament, a so-called "cold" zone 1010, a so-called "hot" zone 101 1 comprising means for heating the filament adapted to melt locally, and a nozzle 1012 through which the molten material is extruded.
Un support 200 est placé en regard de la buse 1012 pour recevoir le matériau fondu et supporter l'objet au cours de sa fabrication par empilement de couches.  A support 200 is placed facing the nozzle 1012 to receive the molten material and support the object during its manufacture by stacking layers.
La zone froide 1010 est maintenue à une température sensiblement inférieure à celle de la zone chaude de sorte à ne pas provoquer de fusion du filament dans ladite zone 1010. En effet, une fusion voire un ramollissement significatif du filament occasionnerait un colmatage de la tête. A cet effet, la zone froide peut comporter des moyens de refroidissement.  The cold zone 1010 is maintained at a temperature substantially lower than that of the hot zone so as not to cause melting of the filament in said zone 1010. Indeed, a melting or even a significant softening of the filament would cause clogging of the head. For this purpose, the cold zone may comprise cooling means.
Sur son trajet vers la tête 101 , le filament est entraîné par des moyens d'entraînement 102 tels que des galets par exemple. Avant d'entrer dans la tête 101 , le filament est guidé dans un tube 103.  On its way to the head 101, the filament is driven by drive means 102 such as rollers for example. Before entering the head 101, the filament is guided in a tube 103.
Naturellement, la structure représentée sur la figure 1 est donnée à titre d'illustration et n'est en aucun cas limitative en ce qui concerne la structure des imprimantes 3D susceptibles d'utiliser le filament selon l'invention.  Naturally, the structure shown in Figure 1 is given by way of illustration and is in no way limiting with respect to the structure of 3D printers capable of using the filament according to the invention.
On va maintenant décrire différents modes de réalisation du filament.  Various embodiments of the filament will now be described.
Par « composition » on entend l'ensemble des constituants de l'âme et de l'enveloppe. Ces constituants comprennent :  By "composition" we mean all the constituents of the soul and the envelope. These constituents include:
- au moins un matériau thermoplastique (ou un mélange de matériaux thermoplastiques) formant une matrice présentant un point de fusion convenant à la fusion dans une tête d'impression d'une imprimante 3D puis à l'extrusion au travers d'une buse en sortie de la tête, et at least one thermoplastic material (or a mixture of thermoplastic materials) forming a matrix having a melting point which is suitable for melting in a print head of a 3D printer and then extruding through a nozzle at the exit of the head, and
- éventuellement : une charge sous la forme de particules (billes, fibres, etc.) et/ou des additifs (par exemple : agents compatibilisants, assouplissants, colorants etc.) permettant d'ajuster les propriétés de la composition.  - optionally: a charge in the form of particles (beads, fibers, etc.) and / or additives (for example: compatibilizing agents, softeners, colorants, etc.) for adjusting the properties of the composition.
L'âme et l'enveloppe présentent des matériaux thermoplastiques qui sont miscibles l'un avec l'autre, de sorte que, bien que l'enveloppe forme une couche distincte de l'âme lorsque le filament est introduit dans l'imprimante 3D, le matériau de l'objet fabriqué est un mélange intime desdits matériaux.  The core and shell have thermoplastic materials that are miscible with each other, so that although the shell forms a separate layer of the core when the filament is introduced into the 3D printer, the material of the manufactured object is an intimate mixture of said materials.
Les compositions de l'âme et de l'enveloppe peuvent différer par la nature de leurs constituants et/ou par la proportion de chaque constituant.  The compositions of the core and the shell may differ in the nature of their constituents and / or in the proportion of each constituent.
La figure 2 illustre un filament selon un mode de réalisation de l'invention. Dans cet exemple, le filament présente une section circulaire, mais l'invention n'est pas limitée à une géométrie particulière. Lorsque le filament n'est pas circulaire, on considère le diamètre d'un filament circulaire dont la section présente une aire identique.  Figure 2 illustrates a filament according to one embodiment of the invention. In this example, the filament has a circular section, but the invention is not limited to a particular geometry. When the filament is not circular, consider the diameter of a circular filament whose section has an identical area.
Le diamètre du filament est typiquement compris entre 1 et 3 mm, les diamètres les plus répandus à l'heure actuelle pour les filaments pour impression 3D étant de 1 ,75 mm, 2,85 mm et 3 mm. Toutefois, ces valeurs ne sont pas limitatives et pourront évoluer selon les besoins du marché.  The diameter of the filament is typically between 1 and 3 mm, the most prevalent diameters at present for the 3D printing filaments being 1.75 mm, 2.85 mm and 3 mm. However, these values are not limiting and may evolve according to the needs of the market.
La fabrication du filament comprend la formation de l'âme par extrusion au travers d'une filière appropriée. L'enveloppe peut être formée par extrusion en même temps que l'âme (coextrusion) ou par une autre technique de recouvrement mise en œuvre au cours de la fabrication de l'âme ou ultérieurement, en reprise. Le procédé de coextrusion est préféré dans la mesure où il permet d'obtenir l'âme et l'enveloppe en une unique opération.  The manufacture of the filament comprises the formation of the core by extrusion through a suitable die. The envelope may be formed by extrusion at the same time as the core (coextrusion) or by another recovery technique implemented during the manufacture of the core or later, in recovery. The coextrusion process is preferred in that it provides the core and shell in a single operation.
Le procédé de fabrication est configuré pour assurer une tolérance très précise sur le diamètre du filament, de l'ordre du centième de millimètre.  The manufacturing process is configured to ensure a very precise tolerance on the diameter of the filament, of the order of a hundredth of a millimeter.
A cet égard, il est à noter que les fils de coupe pour débroussailleuse, qui présentent typiquement un diamètre du même ordre de grandeur que les filaments pour impression 3D décrits dans le présent texte, ne conviennent pas pour l'impression 3D. En effet, le mécanisme d'entraînement du filament dans l'imprimante requiert une très grande précision dimensionnelle du filament, la tolérance sur le diamètre du filament étant, comme indiqué plus haut, de l'ordre du centième de millimètre. Les fils de coupe pour débroussailleuse ne requièrent pas une telle précision dimensionnelle et présentent une tolérance sur le diamètre de l'ordre du dixième de millimètre. Il en résulte que de tels fils ne pourraient être entraînés correctement dans une imprimante 3D, les variations de diamètre engendrant un entraînement irrégulier du fil et occasionnant rapidement un colmatage de la tête d'impression. L'enveloppe 1 1 forme une couche entourant entièrement l'âme 10 et présente une épaisseur sensiblement constante sur toute la périphérie de l'âme et sur la longueur du filament. In this respect, it should be noted that brushcutter cutting lines, which typically have a diameter of the same order of magnitude as the 3D printing filaments described in this text, are not suitable for 3D printing. Indeed, the drive mechanism of the filament in the printer requires a very high dimensional accuracy of the filament, the tolerance on the diameter of the filament being, as indicated above, of the order of a hundredth of a millimeter. Cutting lines for brush cutters do not require such dimensional accuracy and have a tolerance on the diameter of the order of a tenth of a millimeter. As a result, such yarns could not be properly driven into a 3D printer, the diameter variations resulting in uneven yarn drive and rapidly causing clogging of the print head. The envelope January 1 forms a layer completely surrounding the core 10 and has a substantially constant thickness over the entire periphery of the core and over the length of the filament.
L'épaisseur de l'enveloppe est de préférence la plus fine possible pour remplir une fonction de barrière (dont des exemples sont exposés plus bas), sans affecter notablement les propriétés de l'objet obtenu par impression 3D. Ainsi, le matériau de l'enveloppe ne forme qu'une faible proportion du matériau de l'objet formé par impression 3D, qui est constitué d'un mélange intime des matériaux de l'âme et de l'enveloppe.  The thickness of the envelope is preferably as thin as possible to fulfill a barrier function (examples of which are described below), without significantly affecting the properties of the object obtained by 3D printing. Thus, the material of the envelope forms a small proportion of the material of the object formed by 3D printing, which consists of an intimate mixture of the materials of the core and the envelope.
Par exemple, pour un filament de 1 ,75 mm de diamètre, l'épaisseur de l'enveloppe est avantageusement comprise entre 0,05 mm et 0,20 mm ; pour un filament de 2,85 ou 3 mm de diamètre, l'épaisseur de l'enveloppe peut être comprise entre 0,05 mm et 0,30 mm.  For example, for a filament of 1.75 mm in diameter, the thickness of the envelope is advantageously between 0.05 mm and 0.20 mm; for a filament of 2.85 or 3 mm in diameter, the thickness of the envelope may be between 0.05 mm and 0.30 mm.
Selon un mode de réalisation, l'âme comprend une charge sous la forme de particules telles que des fibres ou une poudre.  According to one embodiment, the core comprises a filler in the form of particles such as fibers or a powder.
Parmi les charges préférées, on peut citer :  Among the preferred fillers, mention may be made of:
- du verre,  - glass,
- de l'aramide,  aramid
- du carbone,  - carbon,
- du poly(p-phénylène-2,6-benzobisoxazole) (PBO), commercialisé sous le nom ZYLON™, qui est utilisé dans de nombreux produits demandant une grande résistance mécanique et une bonne stabilité thermique,  poly (p-phenylene-2,6-benzobisoxazole) (PBO), marketed under the name ZYLON ™, which is used in many products requiring high mechanical strength and good thermal stability,
- un métal,  - a metal,
- une céramique.  - a ceramic.
Lesdites charges peuvent se présenter sous la forme de poudre ou de fibres coupées. Eventuellement, il peut s'agir également de fibres continues.  Said fillers may be in the form of powder or cut fibers. Optionally, it may also be continuous fibers.
S'agissant de fibres coupées ou broyées, le diamètre des fibres est typiquement compris entre 18 et 70 μηι. La longueur des fibres peut aller de 50 μηη jusqu'à 100 μηι, voire jusqu'à 500 μηι, des fibres longues ayant pour effet de liant de l'objet fabriqué par impression 3D à partir d'un tel filament.  In the case of chopped or ground fibers, the diameter of the fibers is typically between 18 and 70 μηι. The length of the fibers may range from 50 μηη to 100 μηι, or up to 500 μηι, long fibers having the effect of binding the object produced by 3D printing from such a filament.
Par ailleurs, suivant la nature et la quantité de charges incorporées au matériau de l'âme, lesdites charges peuvent avoir pour un ou plusieurs des effets suivants :  Moreover, depending on the nature and the quantity of charges incorporated in the material of the core, said charges may have for one or more of the following effects:
- augmenter la densité de l'objet,  - increase the density of the object,
- limiter le retrait de l'objet après impression,  - limit the withdrawal of the object after printing,
- améliorer les propriétés mécaniques, thermiques, et/ou de conductivité électrique de l'objet,  to improve the mechanical, thermal and / or electrical conductivity properties of the object,
- modifier l'aspect de l'objet. Par exemple, une forte proportion de charges métalliques dans l'âme permet de donner un aspect métallique à l'objet, d'augmenter sa densité et d'augmenter sa conductivité thermique et/ou électrique. - change the appearance of the object. For example, a high proportion of metal charges in the core makes it possible to give the object a metallic appearance, to increase its density and to increase its thermal and / or electrical conductivity.
Selon un autre exemple, une charge telle que des fibres de verre permet de bloquer le retrait de l'objet et d'augmenter sa résistance mécanique.  According to another example, a filler such as glass fibers makes it possible to block the shrinkage of the object and to increase its mechanical strength.
Naturellement, l'homme du métier pourra utiliser les charges susmentionnées en combinaison, et pourra éventuellement y ajouter d'autres charges.  Naturally, the skilled person may use the aforementioned charges in combination, and may possibly add other charges.
Au contraire de l'âme, l'enveloppe est dépourvue de charges.  Unlike the soul, the envelope is devoid of charges.
Ainsi, l'enveloppe ne présente aucun caractère abrasif susceptible d'endommager les composants de l'imprimante 3D.  Thus, the envelope has no abrasiveness likely to damage the components of the 3D printer.
Des essais comparatifs ont ainsi été réalisés avec d'une part un filament constitué uniquement d'un matériau thermoplastique chargé de fibres de verre et d'autre part un filament conforme à l'invention, comprenant une âme constituée d'un matériau thermoplastique chargé de fibres de verre et une enveloppe constituée d'un matériau thermoplastique non chargé et miscible avec le matériau de l'âme. Avec le premier filament, l'imprimante 3D s'est colmatée en quelques minutes et un démontage de l'imprimante a montré une usure nette des galets d'entraînement du filament. Avec le second filament, l'imprimante a pu être utilisée pendant plusieurs heures sans présenter de signe d'usure.  Comparative tests were thus carried out with, on the one hand, a filament consisting solely of a thermoplastic material filled with glass fibers and, on the other hand, a filament according to the invention, comprising a core made of a thermoplastic material loaded with glass fibers and an envelope made of an unfilled thermoplastic material and miscible with the material of the core. With the first filament, the 3D printer clogged in a few minutes and disassembly of the printer showed a net wear of the filament drive rollers. With the second filament, the printer could be used for several hours without showing signs of wear.
Par ailleurs, l'enveloppe peut avantageusement être en un matériau formant une barrière à l'humidité. Ainsi, même si le matériau de l'âme présente une reprise d'humidité importante, l'enveloppe empêche la pénétration de l'eau au sein du filament et limite ainsi les variations dimensionnelles du filament.  Moreover, the envelope may advantageously be made of a material forming a barrier to moisture. Thus, even if the material of the core has a significant moisture uptake, the envelope prevents the penetration of water within the filament and thus limits the dimensional variations of the filament.
Par exemple, l'âme peut comprendre du PA 6/66/12, qui présente un taux de reprise d'humidité de 4,5% dans une atmosphère à 20°C présentant un taux d'humidité de 50%.  For example, the core may comprise PA 6/66/12, which has a moisture recovery rate of 4.5% in an atmosphere at 20 ° C having a moisture content of 50%.
Selon un autre exemple, l'âme peut comprendre du PA6/66 ou encore du PA6, qui présentent également un taux de reprise d'humidité élevé.  In another example, the core may comprise PA6 / 66 or PA6, which also have a high rate of moisture recovery.
Ces polyamides, qu'ils soient chargés ou non, présentent des propriétés mécaniques intéressantes, permettant d'obtenir des objets présentant une bonne tenue mécanique, y compris en température.  These polyamides, whether loaded or not, have interesting mechanical properties, making it possible to obtain objects having a good mechanical strength, including temperature.
L'enveloppe est avantageusement réalisée en PA12, en PA10 ou en PA1010, qui présentent un taux de reprise d'humidité inférieur à celui du PA6, du PA6/66 ou du PA6/66/12. Ainsi, le PA12 présente un taux de reprise d'humidité relativement faible (de l'ordre de 0,8%) et présente l'avantage d'adhérer parfaitement au matériau de l'âme (notamment s'agissant de PA6/66/12). Le PA10 présente un taux de reprise d'humidité encore plus faible (de l'ordre de 0,4%).  The envelope is advantageously made of PA12, PA10 or PA1010, which have a moisture recovery rate lower than that of PA6, PA6 / 66 or PA6 / 66/12. Thus, the PA12 has a relatively low rate of moisture uptake (of the order of 0.8%) and has the advantage of adhering perfectly to the material of the core (in particular as regards PA6 / 66 / 12). The PA10 has an even lower moisture recovery rate (of the order of 0.4%).
D'une manière plus générale, tout matériau imperméable et/ou présentant un faible taux de reprise d'humidité peut être employé pour former l'enveloppe, pour autant qu'il présente une adhésion suffisante vis-à-vis du matériau de l'âme (lequel n'est pas limité à du polyamide). On évite ainsi la formation de bulles dans l'âme lors du chauffage du filament. More generally, any impervious material and / or having a low rate of moisture uptake may be used to form the envelope, provided that it has sufficient adhesion to the core material (which is not limited to polyamide). This prevents the formation of bubbles in the core during the heating of the filament.
L'enveloppe peut également former une barrière thermique permettant d'éviter un ramollissement excessif d'un filament dont l'âme comprendrait une charge thermiquement conductrice, comprenant typiquement un ou plusieurs métaux. Ladite enveloppe étant dépourvue d'une telle charge, elle procure une isolation thermique de l'âme qui évite le problème de colmatage évoqué en préambule.  The envelope may also form a thermal barrier to prevent excessive softening of a filament whose core would include a thermally conductive filler, typically comprising one or more metals. Said envelope being devoid of such a load, it provides a thermal insulation of the core which avoids the clogging problem mentioned in the preamble.
Naturellement, selon le matériau choisi, l'enveloppe peut remplir tout ou partie des différentes fonctions mentionnées ci-dessus.  Naturally, depending on the chosen material, the envelope can fulfill all or part of the various functions mentioned above.
La figure 3 illustre différentes formes non circulaires que peut prendre la section du filament. L'épaisseur de l'enveloppe 1 1 étant sensiblement constante sur toute la périphérie du filament, la forme de l'âme 10 est sensiblement identique à celle de la section du filament complet.  Figure 3 illustrates various non-circular shapes that can take the section of the filament. The thickness of the casing 1 1 is substantially constant over the entire periphery of the filament, the shape of the core 10 is substantially identical to that of the section of the complete filament.
Bien que les imprimantes 3D actuelles fonctionnent exclusivement avec des filaments de section circulaire (la tête d'impression présentant une ouverture de section circulaire pour le passage du filament), des filaments non circulaires présentant un périmètre augmenté par rapport au périmètre d'un cercle à aire équivalente présentent des avantages particuliers.  Although current 3D printers operate exclusively with circular section filaments (the print head has an opening of circular section for the passage of the filament), non-circular filaments have an increased perimeter relative to the perimeter of a circle to equivalent area have particular advantages.
En effet, un tel filament non circulaire présente une surface de chauffage dans la tête d'impression supérieure à celle d'un filament rond. Par conséquent, à section ou masse égale, le temps de chauffe de ce filament est plus court, et l'on obtient notamment plus rapidement une fusion au centre de l'âme du filament.  Indeed, such a non-circular filament has a heating surface in the print head greater than that of a round filament. Consequently, with a cross section or equal mass, the heating time of this filament is shorter, and in particular a fusion is obtained more rapidly in the center of the core of the filament.
De manière avantageuse, le filament présente une forme polygonale régulière, c'est- à-dire que sa section présente au moins un axe de symétrie, avec des côtés et des angles égaux. Le polygone peut être concave ou convexe. Le polygone s'inscrit avantageusement dans un cercle.  Advantageously, the filament has a regular polygonal shape, that is to say that its section has at least one axis of symmetry, with sides and equal angles. The polygon may be concave or convex. The polygon advantageously fits in a circle.
Un exemple particulièrement préféré est un filament en forme de polygone étoilé, comprenant de trois à huit sommets, de préférence de cinq à huit sommets.  A particularly preferred example is a star-shaped polygon filament comprising from three to eight vertices, preferably from five to eight vertices.
Selon un autre exemple, le filament présente une section hexagonale régulière. In another example, the filament has a regular hexagonal section.
Selon une variante aux polygones précités, le filament peut présenter une forme polygonale « arrondie », c'est-à-dire avec au moins un côté non droit et/ou un sommet non pointu. According to an alternative to the aforementioned polygons, the filament may have a "rounded" polygonal shape, that is to say with at least one non-straight side and / or a non-pointed top.
Pour la mise en œuvre d'un tel filament, certains composants de l'imprimante 3D doivent être adaptés à la forme du filament, mais ces adaptations sont à la portée de l'homme du métier. Enfin, il va de soi que les exemples que l'on vient de donner ne sont que des illustrations particulières en aucun cas limitatives quant aux domaines d'application de l'invention. For the implementation of such a filament, some components of the 3D printer must be adapted to the shape of the filament, but these adaptations are within the reach of the skilled person. Finally, it goes without saying that the examples that we have just given are only particular illustrations in no way limiting as to the fields of application of the invention.

Claims

REVENDICATIONS
1 . Filament (1 ) pour impression 3D, caractérisé en ce qu'il présente une âme (10) présentant une première composition et une enveloppe (1 1 ) entourant l'âme (10) présentant une seconde composition différente de celle de l'âme (10), l'âme et l'enveloppe comprenant chacune un matériau thermoplastique, le matériau thermoplastique de l'enveloppe étant miscible avec celui de l'âme. 1. Filament (1) for 3D printing, characterized in that it has a core (10) having a first composition and an envelope (1 1) surrounding the core (10) having a second composition different from that of the core ( 10), the core and the envelope each comprising a thermoplastic material, the thermoplastic material of the envelope being miscible with that of the core.
2. Filament selon la revendication 1 , présentant une section dont la forme est celle d'un polygone régulier. 2. Filament according to claim 1, having a section whose shape is that of a regular polygon.
3. Filament selon la revendication 2, dont la section est en forme d'étoile. 3. Filament according to claim 2, the section of which is star-shaped.
4. Filament selon la revendication 1 , dont la section est sensiblement celle d'un polygone régulier, avec au moins un côté et/ou un sommet arrondi. 4. Filament according to claim 1, the section of which is substantially that of a regular polygon, with at least one side and/or a rounded vertex.
5. Filament selon l'une des revendications 1 à 4, dans lequel l'âme (10) comprend une charge sous la forme de fibres ou d'une poudre et l'enveloppe (1 1 ) est dépourvue d'une charge. 5. Filament according to one of claims 1 to 4, wherein the core (10) comprises a filler in the form of fibers or a powder and the envelope (1 1) is devoid of a filler.
6. Filament selon la revendication 5, dans lequel la charge de l'âme (10) comprend des fibres de verre, de carbone, de poly(p-phénylène-2,6-benzobisoxazole) (PBO) et/ou d'aramide. 6. Filament according to claim 5, wherein the filler of the core (10) comprises glass, carbon, poly(p-phenylene-2,6-benzobisoxazole) (PBO) and/or aramid fibers .
7. Filament selon la revendication 6, dans lequel les fibres sont des fibres coupées ou broyées présentant un diamètre compris entre 18 et 70 μηη et une longueur comprise entre 50 et 500 μηι. 7. Filament according to claim 6, in which the fibers are cut or crushed fibers having a diameter of between 18 and 70 μηη and a length of between 50 and 500 μηι.
8. Filament selon la revendication 5, dans lequel la charge de l'âme (10) comprend une poudre de particules thermiquement conductrices. 8. Filament according to claim 5, wherein the filler of the core (10) comprises a powder of thermally conductive particles.
9. Filament selon la revendication 8, dans lequel les particules thermiquement conductrices comprennent des particules métalliques. 9. Filament according to claim 8, wherein the thermally conductive particles comprise metallic particles.
10. Filament selon l'une des revendications 1 à 9, dans lequel l'âme (10) comprend du polyamide et l'enveloppe (1 1 ) est réalisée en un matériau imperméable à l'humidité et/ou présentant un taux de reprise d'humidité inférieur à celui du polyamide de l'âme. 10. Filament according to one of claims 1 to 9, in which the core (10) comprises polyamide and the envelope (1 1) is made of a material impermeable to humidity and/or having a recovery rate humidity lower than that of the polyamide of the core.
1 1 . Filament selon la revendication 10, dans lequel l'âme comprend du PA6, du PA6/66 ou du PA6/66/12. 1 1 . Filament according to claim 10, wherein the core comprises PA6, PA6/66 or PA6/66/12.
12. Filament selon l'une des revendications 10 ou 1 1 , dans lequel le matériau de l'enveloppe (1 1 ) comprend du polyamide 12, du polyamide 10 ou du polyamide 1010. 12. Filament according to one of claims 10 or 1 1, in which the material of the envelope (1 1) comprises polyamide 12, polyamide 10 or polyamide 1010.
13. Filament selon l'une des revendications 1 à 12, dans lequel l'enveloppe présente une épaisseur comprise entre 0,05 et 0,30 mm, de préférence entre 0,05 et 0,20 mm. 13. Filament according to one of claims 1 to 12, in which the envelope has a thickness of between 0.05 and 0.30 mm, preferably between 0.05 and 0.20 mm.
14. Filament selon l'une des revendications 1 à 13, dans lequel le diamètre du filament est compris entre 1 et 3 mm. 14. Filament according to one of claims 1 to 13, wherein the diameter of the filament is between 1 and 3 mm.
15. Procédé de fabrication d'un filament (1 ) pour impression 3D selon l'une des revendications 1 à 14, caractérisé en ce que l'enveloppe (1 1 ) est formée autour de l'âme (10) par coextrusion. 15. Method for manufacturing a filament (1) for 3D printing according to one of claims 1 to 14, characterized in that the envelope (1 1) is formed around the core (10) by coextrusion.
16. Procédé de fabrication d'un objet par impression 3D, dans lequel on utilise un filament (1 ) selon l'une des revendications 1 à 14. 16. Method for manufacturing an object by 3D printing, in which a filament (1) according to one of claims 1 to 14 is used.
17. Procédé pour limiter le retrait d'un objet fabriqué par impression 3D au moyen d'une charge contenue dans un filament, dans lequel on fournit un filament (1 ) selon l'une des revendications 5 à 9, on entraîne ledit filament vers une tête d'impression dans lequel ledit filament est chauffé localement, et on extrude le filament fondu au travers d'une buse d'une imprimante 3D de sorte à former l'objet par superposition de couches successives, l'enveloppe préservant les composants de l'imprimante 3D d'une usure par la charge de l'âme. 17. Method for limiting the shrinkage of an object manufactured by 3D printing by means of a charge contained in a filament, in which a filament (1) according to one of claims 5 to 9 is provided, said filament is driven towards a printing head in which said filament is heated locally, and the melted filament is extruded through a nozzle of a 3D printer so as to form the object by superposition of successive layers, the envelope preserving the components of the 3D printer from wear by the load of the core.
18. Procédé pour contrôler le ramollissement d'un filament comprenant une charge de fibres thermiquement conductrices lors de la fabrication d'un objet par impression 3D, dans lequel on fournit un filament (1 ) selon l'une des revendications 8 ou 9, on entraîne ledit filament vers une tête d'impression dans lequel ledit filament est chauffé localement, et on extrude le filament fondu au travers d'une buse d'une imprimante 3D de sorte à former l'objet par superposition de couches successives, l'enveloppe (1 1 ) formant une barrière thermiquement isolante limitant le ramollissement du filament en amont de la zone de la tête d'impression où il est chauffé. 18. Method for controlling the softening of a filament comprising a charge of thermally conductive fibers during the manufacture of an object by 3D printing, in which a filament (1) according to one of claims 8 or 9 is provided, drives said filament towards a print head in which said filament is heated locally, and the melted filament is extruded through a nozzle of a 3D printer so as to form the object by superposition of successive layers, the envelope (1 1) forming a thermally insulating barrier limiting the softening of the filament upstream of the area of the print head where it is heated.
19. Procédé pour éviter la formation de bulles lors de la fabrication d'un objet par impression 3D avec un filament comprenant du polyamide, dans lequel on utilise un filament (1 ) selon l'une des revendications 10 à 12, l'enveloppe (1 1 ) formant une barrière à la reprise d'humidité par le filament. 19. Method for avoiding the formation of bubbles during the manufacture of an object by 3D printing with a filament comprising polyamide, in which a filament (1) according to one of claims 10 to 12 is used, the envelope ( 1 1) forming a barrier to the absorption of moisture by the filament.
PCT/FR2017/051468 2016-06-09 2017-06-09 Filament for 3d printing, method for producing such a filament, and method for producing an object using 3d printing WO2017212190A1 (en)

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FR1655289A FR3052386B1 (en) 2016-06-09 2016-06-09 FILAMENT FOR 3D PRINTING, METHOD FOR MANUFACTURING SUCH A FILAMENT, AND METHOD FOR MANUFACTURING AN OBJECT BY 3D PRINTING
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