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    • 专利摘要:
    Procedure for obtaining a piece by modeling by depositing molten wire. The present invention relates to a method of obtaining a piece of composite material or a ceramic and/or metallic piece by modeling by depositing molten wire. The present invention can be framed in the area of materials science and is therefore of interest to industries that manufacture polymer matrix, ceramic and metal composites for applications in aeronautics, in the production of biomaterials, generation/storage devices energy and refractory materials used in severe service conditions. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2732766A1
    申请号:ES201830503
    申请日:2018-05-24
    公开日:2019-11-25
    发明作者:Montero Ana Ferrández；Fernández Begoña Ferrari；Herencia Antonio Javier Sánchez；Granados Zoilo González；López Francisco Javier González；Domínguez Joaquín Luis Yus；Carrasco Jose Luis González；Rodríguez Marcela Lieblich
    申请人:Consejo Superior de Investigaciones Cientificas CSIC；
    IPC主号:
    专利说明:

    [0001]
    [0002] Procedure for obtaining a piece by modeling by deposition of molten wire.
    [0003]
    [0004] The present invention relates to a method of obtaining a piece of composite material or a ceramic and / or metal part by modeling by deposition of molten wire.
    [0005]
    [0006] The present invention can be framed in the area of materials science and is therefore of interest to industries that manufacture composite materials of polymeric matrix, ceramics and metal for aeronautical applications, in the production of biomaterials, generation / storage devices energy and refractory materials used in severe service conditions.
    [0007]
    [0008] BACKGROUND OF THE INVENTION
    [0009]
    [0010] The processing of composite materials through rapid prototyping techniques has experienced an exponential development in recent years, due to the possibility offered by these techniques to obtain complex geometries or custom shapes, without the need to resort to the use of molds, which engrave and ballast the manufacturing costs and times
    [0011]
    [0012] From the range of 3D printing technologies available, additive fusion molding technologies (Fused Deposition Modeling, FDM, or Fused Filament Fabrication, FFF) enjoy a number of advantages that place them at the head of additive manufacturing. It is a methodology applicable to a wide variety of materials based on the use of thermoplastic polymers such as polylactic acid, acetonitrile-butadiene-styrene, nylon etc., which can act as a single material, matrix or structuring, depending on the amount of thermoplastic containing the final piece printed and / or sintered.
    [0013]
    [0014] The intrinsic limitation of fusion printing has its origin in the thermal properties of the thermoplastic polymer used. Similarly to what is done in other industrial processes of manufacturing of parts by fusion, such as molding by Injection [Preparation of articles using metal injection molding. US 20020144571 A1. EP 0465940 A3], the mixing of the different phases that form the final composite material, is carried out in a conventional way in a dual-use mixer, where the thermoplastic polymer melts, exceeding in all cases its glass transition temperature (Tg ) and fusion (Tm) during the processing time of the starting mixture or of the composite raw material. Moreover, in order to ensure the homogeneity of the final mixture, the mixing process of the different raw materials has an associated milling process and a second fusion mixing, repeating this milling and mixing protocol as many times as necessary. It is for all these reasons that the conventional fusion mixing process can sometimes cause thermal degradation of the material and / or the final mixture.
    [0015]
    [0016] This limitation is aggravated in the printing of an organic-inorganic composite material, where the thermoplastic is the matrix or the structuring additive of the process, since the melting points (Tm) and the glass transition temperatures (Tg) of inorganic materials they are well above the temperature ranges that are usually used in conventional mixing procedures (250-270 ° C). In addition, in melt mixing, the inorganic particles are mixed with the molten thermoplastic polymer, and the high viscosity of these mixtures (> 100 Pas) limits both the amount of inorganic particles and their dispersion in the thermoplastic matrix / structuring. That is why, in many occasions the additive technique cannot be applied directly in the printing of parts with a high load of inorganic particles. Consequently, precision in printing decreases and compromises the final finish of the printed piece. But in addition, in the case of manufacturing by printing 100% inorganic parts, the amount of thermoplastic polymer to print successfully is generally so high (> 30% by volume), that it undermines the consistency and mechanical integrity of the part during the volume contraction processes generated during the sintering heat treatment that consolidate the inorganic structure of the manufactured parts.
    [0017]
    [0018] The research carried out to date on printing techniques focuses on the improvement of parameters related to surface finishing, dimensional accuracy, mechanical properties or process efficiency. In fusion printing, in order to alleviate the process limitations indicated above, modifications on extrusion process have been proposed, such as variations in the velocities of 3D dosing and filament feeding, changes in pressure and temperature gradients, modification of nozzle designs, studies of melt viscosities, addition of stabilizers or other additives, trajectory planning, part orientation, etc. [SC Ligon, R. Liska, J. Stampfl, M. Gurr, R. Mülhaupt, Polymers for 3D Printing and Customized Additive Manufacturing, Chem. Rev. 117 (2017) 10212-10290. doi: 10.1021 / acs.chemrev.7b00074]. However, the efforts dedicated to the study of the mixing process are scarce, even though they are especially relevant, since the dispersion of inorganic particles in the polymer directly affects the homogeneity of the extruded threads, and therefore the specific properties of the final material . In fact it has been shown that the passage of composite materials in a semi-molten state (in the form of granules or thread) through a nozzle can break, cut or agglomerate the particles. This last agglomeration effect could be accentuated by using particles of nanometric size, causing the loss of mechanical properties, since the effect produced by the shear in the printed material is a direct function of the area of the particle-polymer bond.
    [0019]
    [0020] Conventionally, in the printing of thermoplastic and inorganic hybrid materials, after mixing the raw materials, the milled or pelleted material is passed through an extruder, in which the molten mixture passes through a nozzle with a specific diameter, and when cooled acquires a thread form, the thread being the conventional feeding form of fusion printing [Ji Hongbing; Dai Wen; Zeng Yongbin, Metal or ceramic consumable item for FDM 3D printing, preparation method for metal or ceramic consumable item and finished product printing method, CN105665697, 2016].
    [0021]
    [0022] In a literature review on the production of threads or hybrid raw material for fusion printing [S. Singh, S. Ramakrishna, R. Singh, Material issues in additive manufacturing: A review, J. Manuf. Process 25 (2017) 185-200. doi: 10.1016 / j.jmapro.2016.11.006], basic aspects such as the proportion of constituent materials, their composition and nature, etc., and their effects on the mechanical properties of manufactured materials are described. But it also includes, in what way different authors have proposed alternative routes for mixing, such as the use of pre-extrusion milling, in a centrifugal mill [M. Nikzad, SH Masood, I. Sbarski, Thermo-mechanical properties of a highly filled polymeric composites for Fused Deposition Modeling, Mater. Des. 32 (2011) 3448-3456.
    [0023] doi: 10.1016 / j.matdes. 2011.01.056], cryogenic grinding, or using a single screw extruder with a dry mix premix of raw materials [S.H. Masood, W.Q. Song, Development of new metal / polymer materials for rapid tooling using Fused deposition modeling, Mater. Des. 25 (2004) 587-594. doi: 10.1016 / j.matdes.2004.02.009].
    [0024]
    [0025] In more recent works, more innovative mixing methodologies have been carried out in liquid medium. M. Thuyet-Nguyen et al. they have prepared a Ni / ABS mixture by drop casting using a weight ratio of 2: 1 and 1: 1 [M. Thuyet-Nguyen, H. Hai-Nguyen, W.J. Kim, H.Y. Kim, J.-C. Kim, Synthesis and characterization of magnetic of Ni / ABS nanocomposites by electrical explosion of wire in liquid and solution blending methods, Met. Mater. Int. 23 (2017) 391-396. doi: 10.1007 / s12540-017-6533-z], while J. Canales et al. have patented a process for obtaining threads from slippers with a composition of between 30-70% by weight of ceramic material, which incorporate a polymeric mixture of complex formulation, and the printing is based on the presence of gelling agents, that retain their structure above the Tg [Canales Vázquez Jesús; Sánchez Bravo Gloria Begoña; Marín Rueda Juan Ramón; Yagüe Alcaraz Vicente; López López Juan José, Method for Obtaining Ceramic Barbotine for the Production of Filaments for 3D-FDM Printing, Barbotine Obtained using SAID Method, and Ceramic Filaments, WO2017191340, 2017]. None of the proposed processes contemplate the stage of stabilization and / or dispersion of inorganic particles in the liquid and flux medium.
    [0026]
    [0027] In the printing of composite and purely inorganic materials, the fundamental problem lies in obtaining a raw material in the form of yarn, with high inorganic, metal or ceramic load, homogeneously dispersed in the polymer, for the fusion printing of consistent pieces , with final properties, densities, mechanical and functional properties, reproducible. Therefore it is necessary to develop new procedures.
    [0028]
    [0029] DESCRIPTION OF THE INVENTION
    [0030]
    [0031] The present invention relates to a process for obtaining a piece with a composition selected from a purely ceramic or metallic material and a composite material, by modeling by deposition of molten wire.
    [0032] The process of the present invention is of particular interest to the end user, for industries that manufacture polymer matrix composite materials, in applications ranging from aeronautics to biomaterials, and inorganic materials (ceramic and / or metal or metal matrix compounds and / or ceramic) in energy generation / storage devices, biomaterials and, metals and refractory compounds used in severe service conditions. It also has a significant impact on industrial sectors dedicated to the manufacture and marketing of processed raw material and / or commercialization of engineering solutions for capital goods.
    [0033]
    [0034] In a first aspect, the present invention relates to a method of obtaining a part by modeling by deposition of molten wire (hereinafter "process of the invention") comprising the following steps:
    [0035] a) prepare a dispersed and stable suspension of inorganic particles, b) remove the solvent from the suspension obtained in step (a),
    [0036] c) redispersing the product obtained in step (b) in a polymer solution comprising at least one thermoplastic,
    [0037] d) drying the product obtained in step (c) in the absence of temperature, e) determining the extrusion window of the product obtained in step (d) f) extruding the product of step (d) in a temperature range of between the melting temperature and the initial decomposition temperature, obtained in step (e), and
    [0038] g) print the 3D pieces using the product obtained in step (f) using the technique of modeling by deposition of molten wire.
    [0039]
    [0040] Step (a) of the process of the invention relates to the preparation of a dispersed and stable suspension of inorganic particles.
    [0041]
    [0042] Any solvent can be used to prepare the suspension, including water.
    [0043]
    [0044] The inorganic particles used in step (a) are metallic powder, ceramic powder or a combination thereof. Said inorganic particles may be any size that the wire deposition modeling technique allows, including nanometric size. In addition, the inorganic particles of step (a) of the present invention can have any shape.
    [0045] Preferred example of inorganic metal powder particles are
    [0046] • biocompatible metals such as iron, magnesium, titanium,
    [0047] • refractory metals such as nickel, titanium and cobalt and
    [0048] • and a combination thereof
    [0049]
    [0050] Preferred examples of inorganic ceramic powder particles are:
    [0051] • bioactive ceramics such as hydroxyapatite and bioglass,
    [0052] • semiconductor ceramics such as titanium dioxide and zinc oxide, • ceramics of high chemical resistance under extreme conditions such as alumina, zirconia, nitrides and carbides and
    [0053] • any of its combinations.
    [0054]
    [0055] It should be noted that inorganic particles are dispersed by mechanical or sonic means in the suspension.
    [0056]
    [0057] Step (b) of the process of the invention refers to the removal of the solvent from the suspension obtained in step (a).
    [0058]
    [0059] Preferably, said step (b) is carried out by centrifugation or filtration.
    [0060]
    [0061] Step (c) of the process of the invention tries to redisperse the product obtained in step (b) with a polymer solution comprising
    [0062] • at least one polymer or thermoplastic copolymer.
    [0063]
    [0064] Examples of thermostable polymers or copolymers are polyethylene, polylactic acid, polyethylene glycol, polycaprolactone, nylon, acrylonitrile and styrene butadiene.
    [0065]
    [0066] In a preferred embodiment of the process of the present invention, the polymer solution of step (c) further comprises a plasticizer, a dye or an antifoam.
    [0067] It should be noted that inorganic particles are redispersed by mechanical or sonic means in the suspension.
    [0068]
    [0069] Step (d) of the process of the present invention relates to product drying obtained in step (c) in the absence of temperature to avoid deterioration of the thermoset polymeric matrix. Said step (d) is carried out under reduced pressure in a rotary evaporator or by freezing-sublimation.
    [0070]
    [0071] In step (e) of the process of the present invention the determination of the extrusion window of the product obtained in step (d) is carried out. Carrying out this determination is an advantage since it optimizes the extrusion procedure that follows.
    [0072]
    [0073] "Extrusion window" is understood as those temperatures that are necessary to know in order to specify the range of temperatures at which molten wire deposition modeling can be carried out. Specifically, the temperatures to be determined are the following:
    [0074] • melting temperature
    [0075] • initial decomposition temperature
    [0076]
    [0077] The determination of the extrusion window is preferably carried out by thermogravimetry and / or differential scanning calorimetry.
    [0078]
    [0079] In step (f) of the process of the invention, extrusion of the product obtained in step (d) is carried out in a range of temperatures between the melting temperature and the initial decomposition temperature obtained in step (e ). Within this temperature range, printing parameters such as
    [0080] • The diameter of the inlet nozzle
    [0081] • The outlet nozzle diameter
    [0082] • The diameter of the molten thread
    [0083] • The height from which the deposition is carried out
    [0084] • Print speed or deposition
    [0085] • Etc.
    [0086] They can be easily selected.
    [0087]
    [0088] For example, an advantage of the process of the present invention would be that step (f) can be carried out with any outlet nozzle, since the thermal parameters of the starting mixture have been previously determined for the specific composition .
    [0089] The last stage of the process of the invention, step (g) refers to the printing of the 3D pieces using the product obtained in step (f) by the technique of modeling by deposition of molten wire.
    [0090]
    [0091] "Thread deposition modeling" means, in the present invention, that technique of modeling by deposition of a molten mixture, in which an additive technique is used, so that by depositing the material in one or more successive layers conforms to a piece or printed material.
    [0092]
    [0093] An advantage of the process of the present invention, for example, would be that step (g) can also be carried out with any inlet nozzle, since the diameter of the thread has been defined in the extrusion stage (f) , and any outlet nozzle, since the thermal parameters of the starting mixture have been determined previously for the specific composition.
    [0094]
    [0095] In the present invention, the piece that is obtained is a composite material, a purely ceramic piece, a purely metallic piece or a piece formed by a ceramic-metal mixture.
    [0096]
    [0097] When the piece obtained is purely ceramic, purely metallic or is a piece formed by a ceramic-metal mixture:
    [0098] • step (a) of preparing a dispersed and stable suspension of inorganic particles is carried out by surface adsorption of a stabilizer / dispersant to be of a nature such that the homogeneous and stable dispersion of inorganic particles in the matrix takes place polymeric, preferably being a surfactant polymer or a polyelectrolyte,
    [0099] • and the procedure includes the following additional steps:
    [0100] (h), after step (g), of elimination of the polymer comprising the product obtained in step (g) by dissolution or thermal decomposition, and (i) sintering the product obtained in step (h).
    [0101] Examples of surfactant are dodecyl sulfate, oleimine and hexadecyltrimethylammonium bromide.
    [0102]
    [0103] Examples of polyelectrolyte are a polyacrylate, a citrate or a polyamine.
    [0104] In a preferred embodiment of the process of the present invention,
    [0105] • when the piece is purely ceramic, purely metallic or is a piece formed by a ceramic-metal mixture and
    [0106] • when the piece is porous,
    [0107] The volume percentage of the inorganic particles in the mixture obtained in step (d) is greater than 30%.
    [0108]
    [0109] In another preferred embodiment of the process of the present invention,
    [0110] • when the piece is purely ceramic, purely metallic or is a piece formed by a ceramic-metal mixture and
    [0111] • when the piece is dense,
    [0112] The volume percentage of the inorganic particles in the mixture obtained in step (d) is greater than 50%.
    [0113]
    [0114] When the piece obtained is a composite material:
    [0115] • step (a) of preparing a dispersed and stable suspension of inorganic particles is carried out by surface adsorption of a stabilizer / dispersant to be of a nature such that the homogeneous and stable dispersion of inorganic particles in the matrix takes place polymeric, preferably being a polyelectrolyte that is chosen according to the functional group to react with the thermoset polymeric matrix.
    [0116] • the volume percentage of inorganic particles in the mixture obtained in step (d) is greater than 1%.
    [0117]
    [0118] As mentioned above, examples of thermostable polymers or copolymers that are part of the composite part are polyethylene, polylactic acid, polyethylene glycol, polycaprolactone, nylon, acrylonitrile and styrene butadiene.
    [0119]
    [0120] Examples of polyelectrolytes of these thermostable polymers or copolymers are polyacrylates, citrates or polyamines.
    [0121]
    [0122] An advantage of the method of obtaining the present invention, for example, would be that from step (c) the particles interact with the polymer mixture, since the particles have on the surface the stabilizer / dispersant adsorbed on stage (a) that has been selected based on its interaction in the redispersion of stage (c) with the polymers in solution.
    [0123]
    [0124] Another advantage of the process of the present invention, for example, would be that step (c) is carried out at room temperature, which preserves the properties of the polymer matrix in the final piece of composite material.
    [0125]
    [0126] In a preferred embodiment of the process of the present invention, the volume percentage of the inorganic particles in the mixture obtained in step (d) is greater than 10%, preferably greater than 15%.
    [0127]
    [0128] Throughout the description and the claims the word "comprises" and its variants are not intended to exclude other technical characteristics, additives, components or steps. For those skilled in the art, other objects, advantages and features of the invention will be derived partly from the description and partly from the practice of the invention. The following examples and figures are provided by way of illustration, and are not intended to be limiting of the present invention.
    [0129]
    [0130] BRIEF DESCRIPTION OF THE FIGURES
    [0131]
    [0132] Figure 1. Micrographs obtained by scanning electron microscopy at different magnifications of the scaffolding 3D structure of the final piece, printed from the composition wire (1) of example 1: 1A, general image of the scaffolding structure, 1B, micrograph of the cross section of one of the beams and, 1C, a detail of the microstructure of this section.
    [0133]
    [0134] Figure 2. Graphs of the thermogravimetric analysis (2A) and differential scanning calorimetry (2B) of the starting mixture of the composition (1) of Example 1, obtained in the form of a granule after the drying of step (d). The graphs indicate the initial decomposition temperature (in 2A) and the melting temperature (in 2B) with an arrow.
    [0135]
    [0136] Figure 3. Images of the starting mixture of the composition (2) of example 1, obtained in the form of a granule after drying: 3A, photograph of the granules and, 3B, detail micrograph of the microstructure of the granules obtained by microscopy electronics of swept.
    [0137]
    [0138] Figure 4. Images of the composition wire (2) of example 1, obtained after extrusion: 4A, photographs the wire and, 4B, micrograph of the cross section of the wire obtained by scanning electron microscopy.
    [0139]
    [0140] Figure 5. Image of the three-dimensional scaffolding structure of the final piece, printed from the composition wire (2) of example 1.
    [0141]
    [0142] Figure 6. Images of the scaffolding 3D structure of the final piece, printed from the composition wire (3) of example 1: 6A, photograph of the final piece and, 6B, micrograph of the microstructure detail obtained by scanning electron microscopy.
    [0143]
    [0144] Figure 7. Micrographs obtained by scanning electron microscopy at different magnifications of the scaffolding 3D structure of the final piece, printed from the composition wire (1) of example 2: 7A, general image of the scaffolding structure of the printed piece, 7B, micrograph of the cross section of one of the beams and, 7C and 7D, details of the microstructure of the section.
    [0145]
    [0146] Figure 8. Images of the three-dimensional scaffolding structure of the final piece obtained after the heat treatment, and printed from the composition wire (1) of example 2: 8A, photograph of the final piece and, 8B, micrograph of the general structure of the scaffold of the final piece and, 8C, micrograph of the microstructure detail of the cross section of one of the beams, obtained by scanning electron microscopy.
    [0147]
    [0148] Figure 9. Micrographs obtained by scanning electron microscopy at different magnifications of the microstructure detail of the cross-section of an extruded wire from the composition (2) of example 2: 9A, before heat treatment and, 9B, after heat treatment.
    [0149]
    [0150] Figure 10. Images of the starting mixture of the composition (3) of example 2, obtained in the form of a granule after drying: 10A, photograph of the granules and, 10B and 10C, detail micrographs of the microstructure of the obtained granules by scanning electron microscopy.
    [0151]
    [0152] EXAMPLES
    [0153]
    [0154] The invention will now be illustrated by tests carried out by the inventors, which demonstrates the effectiveness of the product of the invention.
    [0155]
    [0156] Example 1: Printing of final pieces of a composite material .
    [0157]
    [0158] Metal / ceramic particle suspensions are prepared by adding a cationic polyelectrolyte as a stabilizer / dispersant, such as:
    [0159]
    [0160] (1) Hydroxyapatite (HA) particles, with an average particle size of 2 pm, with a concentration <35% by volume in aqueous medium at a fixed pH of 8, adding tetramethyl ammonium (HTMA). To this suspension is added polyethyleneimine (PEI> 25,000 KDa) in a proportion of 0.2% by weight with respect to the weight of the ceramic powder. The mixture is subjected to a homogenization grinding process of 45 min.
    [0161]
    [0162] (2) Metallic Magnesium (Mg) particles, with an average particle size of 25 pm, with a concentration <35% by volume in aqueous medium at a fixed pH of 12, adding tetramethyl ammonium (HTMA). To this suspension is added polyethyleneimine (PEI> 25,000 KDa) in a proportion of 0.2% by weight with respect to the weight of Mg, and subsequently the mixture is subjected to a homogenization grinding process of 45 min.
    [0163]
    [0164] (3) Haloisite nanotubes (NTH), with a mean diameter <30 nm and a length <150 pm, with a concentration of 100 g / L in aqueous medium. To this suspension is added polyethyleneimine (PEI> 25,000 KDa) in a proportion of 2% by weight with respect to the weight of the ceramic powder, and subsequently the mixture is dispersed by applying 1 min of ultrasound with a 400 W power probe
    [0165]
    [0166] The resulting suspensions are centrifuged twice, a first time to remove water and change the solvent to tetrahydrofuran (THF), and a second time to remove this last organic solvent. The particles modified with the polyelectrolyte, they are added under mechanical stirring to a solution of polymers in THF in the desired proportion, such proportion being in:
    [0167]
    [0168] (1) 15/85 by volume of HA / PLA.
    [0169]
    [0170] (2) 7/93 by volume of Mg / Polymer, the polymer being a mixture of a thermoplastic such as polylactic acid (PLA) and plasticizer polyethylene glycol (PEG-400) in a ratio 95/5 in volume PLA / PEG-400.
    [0171]
    [0172] (3) 1/99 by volume of HNT / PLA.
    [0173]
    [0174] Ultrasound is applied to disperse and homogenize the suspension.
    [0175]
    [0176] During drying, the solvent is removed under reduced pressure, recovering the solvent, and obtaining the starting mixture in the form of granules. To ensure complete solvent removal, the granules are dried in an oven at 60 ° C for at least 24 h.
    [0177]
    [0178] To determine the working thermal range, the melting temperature and the initial decomposition temperature of the mixture were determined by differential scanning calorimetry (DSC) and thermogravimetric analysis (ATG), respectively, the printing margins being:
    [0179]
    [0180] (1) 152 ° C and 212 ° C, for HA / Polymer composite materials
    [0181]
    [0182] (2) 149 ° C and 264 ° C, for Mg / Polymer composite materials
    [0183]
    [0184] (3) 150 ° C and 265 ° C, for HNT / PLA composite materials
    [0185]
    [0186] The mixtures were extruded at a temperature between 155 ° C and 200 ° C, in a single-use extruder with an exit nozzle of 2.00 mm in diameter, to obtain a filament with a diameter of less than 3.00 mm.
    [0187]
    [0188] With the extruded thread of each composition a three-dimensional piece is printed with a conventional 3D printer to which a head with an input of 3.00 has been attached mm and an outlet nozzle of 0.3 mm, maintaining a plate temperature 60 ° C, and a nozzle temperature of:
    [0189]
    [0190] (1) 160 ° C, for HA / Polymer composite materials
    [0191]
    [0192] (2) 155 ° C, for Mg / Polymer composite materials
    [0193]
    [0194] (3) 182 ° C, for HNT / PLA composites
    [0195]
    [0196] Figure 1 shows micrographs at different magnifications of the structure of the final 3D piece, printed from the starting mixture of composition (1): 15/85 by volume of HA / PLA. In detail (1C) the dispersion of the HA and the polymer matrix can be seen.
    [0197]
    [0198] Figure 2 shows the ATG (2A) and DSC (2B) of the composition granules (1): 15/85 by volume of HA / PLA. Both graphs indicate the temperatures that determine the thermal window: the melting temperature, and the degradation start temperature.
    [0199]
    [0200] Figure 3A shows a photograph of the starting mixture in the form of granules, and Figure 3B shows a detailed micrograph of the mixture of composition (2): 7/93 by volume of Mg / Polymer, where it is seen as a Mg particle is surrounded by polymer.
    [0201]
    [0202] Figure 4A shows a photograph of the extruded yarn from the composition mixture (2) shown in Figure 3, and a micrograph of the cross section of the same in which the dispersion of Mg in the polymer matrix is observed.
    [0203]
    [0204] Figure 5 shows a final 3D piece printed in the form of scaffolding, from yarn shown in Figure 4, obtained from the starting mixture of composition (2).
    [0205]
    [0206] Figure 6A shows a photograph of a final three-dimensional piece, printed in the form of scaffolding and Figure 6B shows a micrograph with the microstructure of the composite material (3), in which the dispersion of the NTHs in the PLA matrix is observed.
    [0207] Example 2: Printing final pieces of a 100% ceramic material
    [0208]
    [0209] Ceramic particle suspensions are prepared by adding a cationic polyelectrolyte as a stabilizer / dispersant, such as:
    [0210]
    [0211] (1) Hydroxyapatite (HA) particles, with an average particle size of 2 pm, with a concentration <35% by volume in aqueous medium at a fixed pH of 8, adding tetramethyl ammonium (HTMA). To this suspension is added polyethyleneimine (PEI> 25,000 KDa) in a proportion of 0.2% by weight with respect to the weight of the ceramic powder. The mixture is subjected to a homogenization grinding process of 45 min.
    [0212]
    [0213] (2) Alumina particles (ALO 3 ), with an average particle size of 0.5 pm, with a concentration <37% by volume in liquid medium. To this suspension an anionic polyelectrolyte is added as a stabilizer, the ammonium salt of a polyacrylic acid (PAA) in a proportion of 1% by weight with respect to the weight of the ceramic powder, and subsequently the mixture is subjected to a grinding process of 2 h homogenization.
    [0214]
    [0215] (3) Zinc Oxide Nanoparticles (ZnO), with an average particle size of <30 nm, with a concentration <5% by volume in aqueous medium. To this suspension is added a surfactant as a stabilizer, hexadecyltrimethylammonium bromide (CTAB), in a proportion of 3% by weight with respect to the weight of the ceramic powder, and subsequently the mixture is dispersed by applying 1 min of ultrasound with a probe of 400 W of power.
    [0216]
    [0217] The resulting suspensions are centrifuged twice, a first time to remove water and change the solvent to tetrahydrofuran (THF), and a second time to remove this last organic solvent. The particles modified with the polyelectrolyte are added under mechanical agitation to a solution of polymers in THF in the desired proportion, such proportion being in:
    [0218]
    [0219] (1) 40/60 by volume of HA / Polymer, the polymer being a mixture of a thermoplastic such as polylactic acid (PLA) and plasticizer polyethylene glycol (PEG-400) in a ratio of 95.3 / 4.7 in volume PLA / PEG-400
    [0220] (2) 50/50 by volume of AI 2 O 3 / Polymer, the polymer being a mixture of a thermoplastic such as polylactic acid (PLA) and plasticizer polyethylene glycol (PEG-400) in a ratio 80/20 in volume PLA / PEG -400
    [0221]
    [0222] (3) 30/70 by volume of ZnO / PLA.
    [0223]
    [0224] Ultrasound is applied to disperse and homogenize the suspension.
    [0225]
    [0226] During drying, the solvent is removed under reduced pressure, recovering the solvent, and obtaining the starting mixture in the form of granules. To ensure complete solvent removal, the granules are dried in an oven at 60 ° C for at least 24 h.
    [0227]
    [0228] To determine the working thermal range, the melting temperature and the initial decomposition temperature of the mixture were determined, as described in example 1.
    [0229]
    [0230] The mixtures (1) and (2) were extruded at a temperature between 160 ° C and 200 ° C, in a single-use extruder with an exit nozzle of 2.00 mm in diameter, to obtain filament with a smaller diameter to 3.00 mm.
    [0231]
    [0232] The extruded yarn from the mixture (2) was subjected to a heat treatment, to thermally decompose the polymer phase and consolidate / densify the ceramic structure; maintaining a constant temperature of 1550 ° C for 60 min, with heating and cooling ramps of 5 ° C / min. After heat treatment, threads of 100% AhO 3 dense composition were obtained.
    [0233]
    [0234] With the thread extruded from the mixture (1), a three-dimensional piece is printed with a conventional 3D printer to which a head with a 3.00 mm inlet and a 0.3 mm outlet nozzle has been attached, maintaining a plate temperature 60 ° C, and a nozzle temperature of 160 ° C, for HA / Polymer composite materials
    [0235]
    [0236] The printed material was subjected to a heat treatment, to thermally decompose the polymer phase and consolidate / densify the ceramic structure; maintaining a constant temperature of 1250 ° C for 90 min, with heating and cooling ramps of 5 ° C / min. After the heat treatment, a three-dimensional piece of 100% HA composition of porous structure was obtained.
    [0237]
    [0238] Figure 7 shows micrographs at different magnifications of the structure of the printed material in the form of scaffolding from the starting mixture of composition (1). The detail of Figure 7A shows the rough surface of the material. The detail in Figure 7B shows the diameter of the bar of approximately 2 mm. The dispersion of HA particles in the polymer matrix can be seen in the detail of Figure 7D. In the detail of Figure 7C it can be seen that with the volume ratio 40/60 HA / Polymer, the HA particles are in contact forming a compaction network, which will enable the consolidation of the ceramic material during sintering, and its stability structural once the polymer has been removed in the thermal process.
    [0239]
    [0240] Figure 8 shows a photograph of the final piece obtained by heat treating the material shown in Figure 7. Figure 8A shows the final piece 100% HA of porous structure obtained after sintering, while Figure 8B shows the micrograph of the Scaffolding structure, and Figure 8C shows a detail of the 100% porous HA microstructure of the already consolidated ceramic piece.
    [0241]
    [0242] Figure 9 shows in detail the microstructures of the yarn obtained from the composition (2), before (9A) and after (9B) of the sintering heat treatment. In the latter, the 100% dense AhO 3 dense microstructure obtained after the heat treatment is observed.
    [0243]
    [0244] Figure 10 shows a photograph (10A) and micrographs (10B and 10C) of the granules obtained from the composition mixture (3). In the detail of the micrograph of Figure 10C shows the homogeneous dispersion of the nanometric phase and the polymer phase.
    权利要求:
    Claims (17)
    [1]
    1- A method of obtaining a piece by modeling by deposition of molten wire comprising the following steps:
    a) prepare a dispersed and stable suspension of inorganic particles, b) remove the solvent from the suspension obtained in step (a),
    c) redispersing the product obtained in step (b) in a polymer solution comprising at least one thermoplastic polymer or copolymer,
    d) drying the product obtained in step (c) under reduced pressure in a rotary evaporator or by freezing-sublimation,
    e) determine the extrusion window of the product obtained in step (d), f) extrude the product of step (d) in a temperature range between the melting temperature and the initial decomposition temperature, and
    g) print the 3D pieces using the product obtained in step (f) using the technique of modeling by deposition of molten wire.
    [2]
    2. The process according to claim 1, wherein the inorganic particles are metallic powder, ceramic powder or a combination thereof.
    [3]
    3. The process according to any one of claims 1 or 2, wherein the inorganic particles are metal powder selected from biocompatible metals, refractory metals and a combination thereof.
    [4]
    4. The method according to any of claims 1 or 2, wherein the inorganic particles are ceramic powder selected from bioactive ceramics, semiconductor ceramics, ceramics of high chemical resistance under extreme conditions and any combination thereof.
    [5]
    5. The process according to any of claims 1 to 4, wherein step (b) is carried out by centrifugation or filtration.
    [6]
    6. The process according to any one of claims 1 to 5, wherein step (c) is carried out by mixing and redispersing the inorganic particles in the polymer mixture by mechanical or sonic means.
    [7]
    7. The process according to any of claims 1 to 6, wherein the thermoplastic is selected from polyethylene, polylactic acid, polyethylene glycol, polycaprolactone, nylon, acrylonitrile and styrene butadiene.
    [8]
    8. The process according to any of claims 1 to 7, wherein the polymer solution of step (c) further comprises a plasticizer, a dye or an antifoam.
    [9]
    9. The method according to any of claims 1 to 8, wherein step (e) is carried out by thermogravimetry and / or differential scanning calorimetry.
    [10]
    10. The method according to any of claims 1 to 9, wherein
    • the piece is purely ceramic, purely metallic or is a piece formed by a ceramic-metal mixture
    • step (a) is carried out by surface adsorption of a surfactant or a polyelectrolyte, the process comprises the following additional steps: (h), after step (g), of removal of the polymer comprising the product obtained in step (g) by dissolution or thermal decomposition, and (i) sintering the product obtained in step (h).
    [11]
    11. The process according to claim 10, wherein the surfactant of step (a) is selected from dodecyl sulfate, oleimine and hexadecyltrimethylammonium bromide.
    [12]
    12. The method according to claim 10, wherein the polyelectrolyte of step (a) is selected from a polyacrylate, a citrate or a polyamine.
    [13]
    13. The process according to any of claims 10 to 12, wherein the piece is porous and the volume percentage of the inorganic particles in the mixture obtained in step (d) is greater than 30%.
    [14]
    14. The process according to any of claims 10 to 12, wherein the part is dense and the volume percentage of the inorganic particles in the mixture obtained in step (d) is greater than 50%.
    [15]
    15. The method according to any of claims 1 to 9, wherein
    • the piece is a composite material,
    • step (a) is carried out by surface adsorption of a polyelectrolyte and • the volume percentage of the inorganic particles in the mixture obtained in step (d) is greater than 1%.
    [16]
    16. The method according to claim 15, wherein the polyelectrolyte of step (a) is selected from a polyacrylate, a citrate or a polyamine.
    [17]
    17. The method according to any of claims 15 or 16, wherein the volume percentage of the inorganic particles in the mixture obtained in step (d) is greater than 15%.
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    同族专利:
    公开号 | 公开日
    EP3805184A1|2021-04-14|
    WO2019224418A1|2019-11-28|
    ES2732766B2|2021-01-20|
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    ES201830503A|ES2732766B2|2018-05-24|2018-05-24|Procedure for obtaining a part by modeling by deposition of molten wire|ES201830503A| ES2732766B2|2018-05-24|2018-05-24|Procedure for obtaining a part by modeling by deposition of molten wire|
    EP19759629.9A| EP3805184A1|2018-05-24|2019-05-24|Method for obtaining a piece by fused filament deposition modelling|
    PCT/ES2019/070348| WO2019224418A1|2018-05-24|2019-05-24|Method for obtaining a piece by fused filament deposition modelling|
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