WO2015173439A1 - Method for producing starting materials for additive manufacturing - Google Patents

Method for producing starting materials for additive manufacturing Download PDF

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Publication number
WO2015173439A1
WO2015173439A1 PCT/ES2014/000207 ES2014000207W WO2015173439A1 WO 2015173439 A1 WO2015173439 A1 WO 2015173439A1 ES 2014000207 W ES2014000207 W ES 2014000207W WO 2015173439 A1 WO2015173439 A1 WO 2015173439A1
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Prior art keywords
additive manufacturing
starting materials
nanoadditives
preparing starting
polymer
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PCT/ES2014/000207
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Spanish (es)
French (fr)
Inventor
Sergio Ignacio Molina Rubio
José Javier RELINQUE MADROÑAL
Manuel German GARCIA ROMERO
David SALES LERIDA
Jesus Hernandez Saz
Francisco Javier DELGADO GONZALEZ
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Universidad De Cádiz (Otri)
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Publication of WO2015173439A1 publication Critical patent/WO2015173439A1/en

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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C67/00Shaping techniques not covered by groups B29C39/00 - B29C65/00, B29C70/00 or B29C73/00
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/005Reinforced macromolecular compounds with nanosized materials, e.g. nanoparticles, nanofibres, nanotubes, nanowires, nanorods or nanolayered materials
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00Additive 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
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B82NANOTECHNOLOGY
    • B82YSPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00Nanotechnology for materials or surface science, e.g. nanocomposites
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00Manufacture of articles or shaped materials containing macromolecular substances
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00Use of inorganic substances as compounding ingredients
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K2201/00Specific properties of additives
    • C08K2201/011Nanostructured additives

Definitions

  • the described invention comprises both a process of manufacturing materials and some products developed by it.
  • the process includes surface coating by means of certain additives, with at least one of its dimensions in the nanometric order, of a polymeric base material and its subsequent melt mixing and extrusion.
  • the application of this process of elaboration provides as a result a filament of material, useful for its application in machines of additive manufacturing as starting material.
  • the invention can be framed within the field of materials research, more specifically in the area of nanomaterials, since the additives used are nanoadditive in accordance with what is expressed above.
  • the present invention will procure materials with different properties that improve those of those that are conventionally used. What will be applicable in industrial manufacturing linked to the aeronautical and consumer goods sector, among other sectors.
  • the invention described herein consists of a process of manufacturing materials for additive manufacturing.
  • the development of manufacturing techniques runs parallel to the need to find materials that are increasingly resistant, reliable and durable, while being economical, recyclable and environmentally friendly.
  • the manufacturing or additive synthesis comprises a series of industrial manufacturing techniques where the fundamental principle is to elaborate, from a model generated by computer-aided design (3D-CAD), a three-dimensional part or complete element in a single process.
  • 3D-CAD computer-aided design
  • the basis on which additive manufacturing is based is the layer-by-layer growth of the material: each layer constitutes a cross-section of the piece that is manufactured, as thin as possible (Gibson, I .; Rosen, DW; Stucker, B. Additive manufacturing technologies: rapid prototyping to direct digital manufacturing; Springer, 2010).
  • nanocomposites or nanocomposites are materials based on a polymer matrix that contains structures of different nature, with the particularity that said structures have at least one of their dimensions in the nanometric order (Raquez, J.-M., et al. Prog.
  • the sintered selective laser from English Selective Laser Sintering, SLS
  • SLS is a additive manufacturing technique based on the production of parts or part parts from powder-shaped material (Zheng, H., et al. Mater. Lett. 2006, 60, 1219), (Liu, FR, al. International Journal of Machine Tools and Manufacture 2013, 65, 22).
  • the SLS process is based on the layer-to-layer fusion of a starting powder that is distributed homogeneously over the work area.
  • the powder is fed to a chamber where a laser beam is focused on the corresponding bed, so that the material melts according to a pattern according to which a cross section of the piece is obtained.
  • the dust that surrounds this section is removed and reused in subsequent layers until it is manufactured (Gibson, I .; Rosen, DW; Stucker, B. Additive manufacturing technologies: rapid prototyping to direct digital manufacturing; Springer, 2010 ).
  • Fused deposition modeling is another technique in which a polymeric filament is passed through a micro-extruder to deposit it layer by layer, allowing the solidification of each, until completing the piece or part of the designed part (Gibson, I; Rosen, DW; Stucker, B. Additive manufacturing technologies: rapid prototyping to direct digital manufacturing; Springer, 2010).
  • the filaments used are obtained by means of an extrusion process in which certain starting materials are used, usually in granulated form or pellet.
  • Stereolithography is a technique whereby a three-dimensional piece is generated by layer-to-layer deposition, in this case of a resin, in a photopolymerization process: a UV laser beam moves according to a computer-controlled pattern to perform the above deposition (Sánchez-Salcedo, S. et al. Chem. Eng. J. Amsterdam, Neth. 2008, 137, 62).
  • Emulsion polymerization Starting from the polymer initiating monomer, the dispersion of nanoadditives is carried out in the solution containing said monomer and the catalysts required in each case to achieve in situ polymerization (Ding, X., et al. Mater Lett. 2004, 58, 3126), (Ye, D., et al. J. Appl. Polym. Sci. 2012, 125, El 17), (Li, Q.-h., et al. Trans. Nonferrous Met. Soc. China 2013, 23, 1421).
  • a hot mixture of the precursors (nanoadditive and polymer matrix) is carried out in an equipment designed to homogenize and compress the mixture through a nozzle, so that a thread of the nanocomposite material is obtained.
  • Said thread is usable in machines for additive manufacturing (Jonoobi, M, et al. Compos. Sci. Technol. 2010, 70, 1742), (Villmow, T., et al. Polymer 2008, 49, 3500), (Eyholzer, C, et al. J. Polym. Environ. 2012, 20, 1052).
  • the nanoadditives are added to the hot polymer, at a temperature higher than the melting temperature (Iwatake, A., et al. Composites Science and Technology 2008, 68, 2103), (Goodridge, RD, et al. Polym. Test. 2011, 30, 94).
  • the procedure is similar to the previous one, although the material is not processed in the form of thread but as granulated material or pellet, which subsequently processed acquires utility in different additive manufacturing processes.
  • the present invention consists in the elaboration of a nano-additive biodegradable polymer wire, by means of the extrusion technique prior to mechanical coating of the polymer in a ball mill.
  • the novelty of the proposed invention is to make a surface coating of the polymer with the nanoadditive, instead of pursuing the perfect mechanical or chemical mixing, prior to extrusion.
  • the dispersion is achieved by homogenization that the rotating spindle of the corresponding machine is capable of conferring on the hot mix of the nanoadditive coated polymer. In this way a simple elaboration process is achieved, not previously described.
  • Additive manufacturing is carried out following a manufacturing concept where the conventional processes for obtaining parts for industrial and consumer use, based on different machining techniques that give rise to a manufacturing in stepped processes, are overcome by obtaining parts in a way automatic and in a single process faster and with lower material losses.
  • the industrial scale implementation of these new production processes requires a research effort aimed at minimizing material and equipment costs, so that additive manufacturing processes are more profitable than conventional ones.
  • the object of the invention is to provide a solution to the problem of developing new materials for additive manufacturing, providing nanocomposite materials and a procedure that allows greater simplification. technique than others applied, while the improvement of properties of materials of conventional use in additive manufacturing has been pursued by the inclusion of nanoadditives, following the elaboration procedure described below by the present invention.
  • a procedure for developing starting materials for additive manufacturing has been devised for the purpose of the invention, consisting of a sequential two-step process that will be described in detail.
  • a mechanical coating is carried out based on introducing into a suitable grinding equipment, specifically a planetary ball mill, the starting polymer in the form of granules and the corresponding nanoadditive together with an adequate load of moving elements, which procure the contact between the granulated polymer and the nanoadditive.
  • the material thus prepared is subjected to melt mixing with extrusion to obtain a filament of nanocomposite material, achieving homogenization of the nanoadditive by dispersion through the polymer matrix.
  • the planetary ball mill is a team consisting of a turntable on which the grinding vessel is fixed, however allowing the rotation movement (hence the planetary designation: the turning mechanism of the grinding plate-glass assembly is similar to celestial kinematics).
  • the equipment transmits to the grinding vessel, or glass itself, an angular speed of rotation during a certain time.
  • the mobile elements introduced into the grinding vessel, balls at the time, are subjected to a random movement caused by the centrifugal force itself that the glass, by turning, confers on the balls and their own collisions.
  • the polymer introduced as particulate matter of millimeter granulometry is subjected to multiple collisions against the balls and walls of the grinding vessel, the surface coating being produced through this mechanism, since the nanoadditive has been introduced as Load the glass.
  • Extrusion is a conventional process in the production of materials for additive manufacturing, so the novel thing in the present invention consists in coating pellets of polymeric material with the nanoadditive, by means of the grinding process described, as a previous step to the said one mixed in rounded with extrusion.
  • the operation variables for grinding will be the loading and type of balls, loading of material (polymer and nanoadditive) to the vessel, coating time and angular speed of rotation of the mill plate.
  • a Y-Zr oxide grinding vessel a ceramic with high impact and abrasion resistance and balls thereof has been used.
  • balls of the smallest possible size should be used. Since the reduction of the pellets is not desired (and in addition it is not possible given its eminently plastic mechanical behavior) but only the surface coating with the nanoadditive, it has been decided to use the largest available balls. Specifically, a set of 25 balls of 20 mm 0 has been used. Once the ball load is known and fixed, it is necessary to determine the recommended material load to the vessel.
  • pellets of biodegradable plastics type PLA / PHA (of English Polylactic acid / Polyhydroxyalkanoate) and of PLA have been coated with nanoadditives such as graphite sheets of nanometric thickness, GNP (of English Graphite Nano-Platelets) and functionalized nanoparticles of Ag, Au and other precious metals, to favor the excitation of surface plasmons at nanoscale.
  • nanoadditives such as graphite sheets of nanometric thickness, GNP (of English Graphite Nano-Platelets) and functionalized nanoparticles of Ag, Au and other precious metals
  • PLA / PHA nano-additive with GNP has been prepared by the described manufacturing process, by mechanical coating followed by melt mixing with extrusion, to obtain a filament of nanocomposite material with a homogeneous dispersion of the nanoadditive in the polymer matrix.
  • This material has been applied in additive manufacturing, specifically by modeling by deposition of rounded. The determination of thermal properties has confirmed the non-degradation of the polymer at the working temperature of the aforementioned additive manufacturing machine.
  • the weights corresponding to the polymer and nanoadditive load together with the balls in the quantities indicated in the description of the invention shall be introduced into the grinding vessel.
  • the nanoadditive load should be adjusted to the desired weight percentage of polymer.
  • the grinding vessel must be fixed to the plate of the corresponding planetary ball mill and, once secured, set the conditions for angular plate speed and grinding time.
  • the balls After the grinding time has elapsed, the balls must be separated from the coated polymer after the previous step and the second one must be collected as material prepared for extrusion melt mixing.
  • the loading of pellets is introduced into the loading hopper of an extruder whose spindle will rotate at a certain speed forcing the polymer to pass through the body divided into heated sections thereof.
  • the extruder machine concludes in a small diameter nozzle through which the polymer will flow forming a thread.
  • the thread of the fourth step must be cooled for solidification in a water bath arranged at the exit of the extrusion equipment.
  • the filament thus formed is collected and coiled conveniently, being prepared for disposal in machines for additive manufacturing of molten deposition modeling.
  • An example of elaboration is as follows: 130 g of PLA together with 0.1% w / w of GNP, placed next to 25 balls of 20 mm 0 of Y-Zr oxide in a commercial grinding glass of a mill Retsch planetary ball model PM100. This load is stirred in the mill for 15 min at 350 rpm, achieving the surface coating of the PLA pellets by the GNP.
  • This material is injected into an extruder with a spindle rotation speed of 50 rpm and heated sections with temperatures ranging from 160-180 ° C, to obtain a constant diameter filament of 1.75 mm.
  • the invention includes a process for the preparation of filaments of nanocomposite materials for additive manufacturing as well as some of the formulations described and claimed.
  • the object of industrial application itself is the filament, which is the starting material for molten deposition modeling machines, FDM.

Abstract

The invention relates to a method for producing starting materials for polymer-based additive manufacturing with addition of nanostructured components, consisting of two sequential processes: mechanically covering the surface of the biodegradable polymer matrix with nanoadditives by means of ball milling, followed by melt-mixing by extrusion. This method allows the production of a filament of nanocomposite material for direct application as a starting material in additive manufacturing processes by means of fused deposition modelling.

Description

PROCEDIMIENTO DE ELABORACIÓN DE MATERIALES DE PARTIDA PARA FABRICACIÓN ADITIVA.  PROCEDURE FOR THE PREPARATION OF STARTING MATERIALS FOR ADDITIVE MANUFACTURING.
SECTOR DE LA TÉCNICA SECTOR OF THE TECHNIQUE
La invención descrita comprende tanto un procedimiento de elaboración de materiales como algunos productos desarrollados por el mismo. El procedimiento incluye el recubrimiento superficial mediante determinados aditivos, con al menos una de sus dimensiones en el orden nanométrico, de un material de base polimérica y su ulterior mezclado en fundido y extrusión. La aplicación de este procedimiento de elaboración proporciona como resultado un filamento de material, útil para su aplicación en máquinas de fabricación aditiva como material de partida. The described invention comprises both a process of manufacturing materials and some products developed by it. The process includes surface coating by means of certain additives, with at least one of its dimensions in the nanometric order, of a polymeric base material and its subsequent melt mixing and extrusion. The application of this process of elaboration provides as a result a filament of material, useful for its application in machines of additive manufacturing as starting material.
La invención puede encuadrarse dentro del campo de investigación en materiales, más concretamente en el área de nanomateriales, puesto que los aditivos empleados tienen carácter de nanoaditivos de acuerdo a lo expresado ut supra. En el contexto de la investigación actual en materiales para fabricación aditiva, la presente invención procurará materiales con distintas propiedades que mejoran las de aquellos que se emplean convencionalmente. Lo que será de aplicación en la fabricación industrial vinculada al sector aeronáutico y de bienes de consumo, entre otros sectores.  The invention can be framed within the field of materials research, more specifically in the area of nanomaterials, since the additives used are nanoadditive in accordance with what is expressed above. In the context of current research in materials for additive manufacturing, the present invention will procure materials with different properties that improve those of those that are conventionally used. What will be applicable in industrial manufacturing linked to the aeronautical and consumer goods sector, among other sectors.
ESTADO DE LA TÉCNICA STATE OF THE TECHNIQUE
La invención que se describe en la presente memoria consiste en un procedimiento de elaboración de materiales para fabricación aditiva. El desarrollo de las técnicas de fabricación discurre paralelo a la necesidad de encontrar materiales cada vez más resistentes, confiables y duraderos al tiempo que económicos, reciclables y respetuosos con el medio ambiente. En este sentido, la fabricación o síntesis aditiva comprende una serie de técnicas de fabricación industrial donde el principio fundamental consiste en elaborar, a partir de un modelo generado por diseño asistido por ordenador (3D-CAD), una pieza o elemento completo tridimensionales en un solo proceso. La base sobre la que estriba la fabricación aditiva es el crecimiento capa a capa del material: cada capa constituye una sección transversal de la pieza que se fabrica, de un espesor lo más fíno posible (Gibson, I.; Rosen, D. W.; Stucker, B. Additive manufacturing technologies: rapid prototyping to direct digital manufacturing; Springer, 2010).The invention described herein consists of a process of manufacturing materials for additive manufacturing. The development of manufacturing techniques runs parallel to the need to find materials that are increasingly resistant, reliable and durable, while being economical, recyclable and environmentally friendly. In this sense, the manufacturing or additive synthesis comprises a series of industrial manufacturing techniques where the fundamental principle is to elaborate, from a model generated by computer-aided design (3D-CAD), a three-dimensional part or complete element in a single process. The basis on which additive manufacturing is based is the layer-by-layer growth of the material: each layer constitutes a cross-section of the piece that is manufactured, as thin as possible (Gibson, I .; Rosen, DW; Stucker, B. Additive manufacturing technologies: rapid prototyping to direct digital manufacturing; Springer, 2010).
En virtud de lo antedicho, y con la intención de encontrar materiales con propiedades mejoradas para fabricación aditiva, deben considerarse las múltiples posibilidades que supone el campo de la nanotecnología: en efecto, las propiedades macroscópicas de los materiales son muy variables en la escala nanométrica y ello la hace particularmente interesante a la hora de mejorar las propiedades de materiales convencionales formando nuevos materiales compuestos: los denominados nanocomposites o nanocompuestos (Haghi, A. K.; Zaikov, G. E. Update on Nanofíllers in Nanocomposites: From Introduction to Application; Smithers Rapra, 2013). En particular, los nanocomposites de base polimérica son materiales basados en una matriz de polímero que contiene estructuras de diversa naturaleza, con la particularidad de que dichas estructuras poseen al menos una de sus dimensiones en el orden nanométrico (Raquez, J.-M., et al. Prog. Polym. Sci. 2013, 38, 1504), (Hussain, F., et al. J. Compos. Mater. 2006, 40, 1511). El propósito de la inclusión de estas estructuras es la mejora y optimización de las propiedades de la matriz, así, la adición de sustancias nanoparticuladas a matrices poliméricas presenta la ventaja de permitir la manipulación de las propiedades de los objetos fabricados, a través del conocimiento y control de los procesos de fabricación y de la caracterización de los materiales, en un proceso de continua realimentación. By virtue of the above, and with the intention of finding materials with improved properties for additive manufacturing, the multiple possibilities of the nanotechnology field must be considered: in fact, the macroscopic properties of the materials are very variable in the nanometric scale and This makes it particularly interesting when it comes to improving the properties of conventional materials by forming new composite materials: the so-called nanocomposites or nanocomposites (Haghi, AK; Zaikov, GE Update on Nanofillers in Nanocomposites: From Introduction to Application; Smithers Rapra, 2013). In particular, polymer-based nanocomposites are materials based on a polymer matrix that contains structures of different nature, with the particularity that said structures have at least one of their dimensions in the nanometric order (Raquez, J.-M., et al. Prog. Polym. Sci. 2013, 38, 1504), (Hussain, F., et al. J. Compos. Mater. 2006, 40, 1511). The purpose of the inclusion of these structures is the improvement and optimization of the properties of the matrix, thus, the addition of nanoparticulate substances to polymeric matrices has the advantage of allowing the manipulation of the properties of the manufactured objects, through knowledge and control of manufacturing processes and characterization of materials, in a process of continuous feedback.
Entre las técnicas principales de fabricación aditiva cabe destacar como más significativas el sinterizado láser selectivo, modelado por deposición de fundido y estereolitografía. Cabe indicar que el término "impresión 3D" también se ha hecho muy popular a la hora de referirse a las técnicas de fabricación aditiva. El sinterizado láser selectivo (del inglés Selective Láser Sintering, SLS), es una técnica de fabricación aditiva basada en la producción de piezas o partes de pieza a partir de material en forma pulverulenta (Zheng, H., et al. Mater. Lett. 2006, 60, 1219), (Liu, F. R., el al. International Journal of Machine Tools and Manufacture 2013, 65, 22). El proceso SLS se basa en la fusión capa a capa de un polvo de partida que se distribuye de forma homogénea sobre el área de trabajo. El polvo se alimenta a una cámara donde un haz láser se focaliza sobre el correspondiente lecho, de modo que se funde el material de acuerdo a un patrón según el que se obtiene una sección transversal de la pieza. El polvo que rodea esta sección se retira y se reaprovecha en las capas subsecuentes hasta completar la fabricación de la misma (Gibson, I.; Rosen, D. W.; Stucker, B. Additive manufacturing technologies: rapid prototyping to direct digital manufacturing; Springer, 2010).Among the main techniques of additive manufacturing, the most significant is the selective laser sintering, modeling by melting deposition and stereolithography. It should be noted that the term "3D printing" has also become very popular when referring to additive manufacturing techniques. The sintered selective laser (from English Selective Laser Sintering, SLS), is a additive manufacturing technique based on the production of parts or part parts from powder-shaped material (Zheng, H., et al. Mater. Lett. 2006, 60, 1219), (Liu, FR, al. International Journal of Machine Tools and Manufacture 2013, 65, 22). The SLS process is based on the layer-to-layer fusion of a starting powder that is distributed homogeneously over the work area. The powder is fed to a chamber where a laser beam is focused on the corresponding bed, so that the material melts according to a pattern according to which a cross section of the piece is obtained. The dust that surrounds this section is removed and reused in subsequent layers until it is manufactured (Gibson, I .; Rosen, DW; Stucker, B. Additive manufacturing technologies: rapid prototyping to direct digital manufacturing; Springer, 2010 ).
El modelado por deposición de fundido (del inglés Fused Deposition Modeling, FDM), es otra técnica en la que se hace pasar un filamento polimérico por una micro-extrusora para depositarlo capa a capa, permitiéndose la solidificación de cada una, hasta completar la pieza o parte de pieza diseñada (Gibson, I; Rosen, D. W.; Stucker, B. Additive manufacturing technologies: rapid prototyping to direct digital manufacturing; Springer, 2010). Los filamentos utilizados se obtienen mediante un proceso de extrusión en el que se hace uso de determinados materiales de partida, usualmente en forma granulada o pellet. Fused deposition modeling (Fused Deposition Modeling, FDM), is another technique in which a polymeric filament is passed through a micro-extruder to deposit it layer by layer, allowing the solidification of each, until completing the piece or part of the designed part (Gibson, I; Rosen, DW; Stucker, B. Additive manufacturing technologies: rapid prototyping to direct digital manufacturing; Springer, 2010). The filaments used are obtained by means of an extrusion process in which certain starting materials are used, usually in granulated form or pellet.
La estereolitografía es una técnica por la que una pieza tridimensional es generada por la deposición capa a capa, en este caso de una resina, en un proceso de fotopolimerización: un haz láser UV se mueve de acuerdo a un patrón controlado por ordenador para realizar la antedicha deposición (Sánchez-Salcedo, S. et al. Chem. Eng. J. Amsterdam, Neth. 2008, 137, 62). Stereolithography is a technique whereby a three-dimensional piece is generated by layer-to-layer deposition, in this case of a resin, in a photopolymerization process: a UV laser beam moves according to a computer-controlled pattern to perform the above deposition (Sánchez-Salcedo, S. et al. Chem. Eng. J. Amsterdam, Neth. 2008, 137, 62).
Los materiales para fabricación aditiva pueden clasificarse según la metodología empleada para su elaboración. Así, entre las diversas técnicas descritas en la bibliografía, cabe destacar las siguientes, agrupadas por su carácter físico o químico: Vía química Materials for additive manufacturing can be classified according to the methodology used for its preparation. Thus, among the various techniques described in the bibliography, it is worth highlighting the following, grouped by their physical or chemical character: Chemical route
- Solución de precursores: Los nanoaditivos, funcionalizados o no según convenga para favorecer la dispersión (Raquez, J.-M., et al. Prog. Polym. Sci. 2013, 38, 1504), son introducidos en solución junto al polímero, previamente solubilizado, y los catalizadores requeridos en cada caso (Shameli, K., et al. Int. J. Nanomed. 2010, 5, 573), (Fortunati, E., et al. J. Food Eng. 2013, 118, 117), (Pillai, S. K., et al. J. Appl. Polym. Sci. 2013, 129, 362).  - Solution of precursors: The nanoadditives, functionalized or not as appropriate to favor dispersion (Raquez, J.-M., et al. Prog. Polym. Sci. 2013, 38, 1504), are introduced in solution together with the polymer, previously solubilized, and the catalysts required in each case (Shameli, K., et al. Int. J. Nanomed. 2010, 5, 573), (Fortunati, E., et al. J. Food Eng. 2013, 118, 117), (Pillai, SK, et al. J. Appl. Polym. Sci. 2013, 129, 362).
- Polimerización en emulsión: Partiendo del monómero iniciador del polímero, se lleva a cabo la dispersión de nanoaditivos en la solución que contiene dicho monómero y los catalizadores requeridos en cada caso para lograr la polimerización in situ (Ding, X., et al. Mater. Lett. 2004, 58, 3126), (Ye, D., et al. J. Appl. Polym. Sci. 2012, 125, El 17), (Li, Q.-h., et al. Trans. Nonferrous Met. Soc. China 2013, 23, 1421).  - Emulsion polymerization: Starting from the polymer initiating monomer, the dispersion of nanoadditives is carried out in the solution containing said monomer and the catalysts required in each case to achieve in situ polymerization (Ding, X., et al. Mater Lett. 2004, 58, 3126), (Ye, D., et al. J. Appl. Polym. Sci. 2012, 125, El 17), (Li, Q.-h., et al. Trans. Nonferrous Met. Soc. China 2013, 23, 1421).
Vía física  Physical way
- Extrusión: Se realiza una mezcla en caliente de los precursores (nanoaditivo y matriz polimérica) en un equipo diseñado al efecto de homogenizar y comprimir la mezcla a través de una boquilla, de modo tal que se obtenga un hilo del material nanocompuesto. Dicho hilo es utilizable en máquinas para fabricación aditiva (Jonoobi, M, et al. Compos. Sci. Technol. 2010, 70, 1742), (Villmow, T., et al. Polymer 2008, 49, 3500), (Eyholzer, C, et al. J. Polym. Environ. 2012, 20, 1052).- Extrusion: A hot mixture of the precursors (nanoadditive and polymer matrix) is carried out in an equipment designed to homogenize and compress the mixture through a nozzle, so that a thread of the nanocomposite material is obtained. Said thread is usable in machines for additive manufacturing (Jonoobi, M, et al. Compos. Sci. Technol. 2010, 70, 1742), (Villmow, T., et al. Polymer 2008, 49, 3500), (Eyholzer, C, et al. J. Polym. Environ. 2012, 20, 1052).
- Mezclado en fundido: Los nanoaditivos se añaden al polímero en caliente, a una temperatura superior a la de fusión del mismo (Iwatake, A., et al. Composites Science and Technology 2008, 68, 2103), (Goodridge, R. D., et al. Polym. Test. 2011, 30, 94). El procedimiento es similar al anterior, si bien el material no se procesa en forma de hilo sino como material granulado o pellet, que por ulterior procesado adquiere utilidad en distintos procesos de fabricación aditiva. - Melt mixing: The nanoadditives are added to the hot polymer, at a temperature higher than the melting temperature (Iwatake, A., et al. Composites Science and Technology 2008, 68, 2103), (Goodridge, RD, et al. Polym. Test. 2011, 30, 94). The procedure is similar to the previous one, although the material is not processed in the form of thread but as granulated material or pellet, which subsequently processed acquires utility in different additive manufacturing processes.
- Otros: Se contemplan varias formas de elaboración de nanocompuestos vía física, normalmente vinculados a la extrusión, como etapa previa a ésta. Molienda (Qian, Z., et al. Polym. Eng. Sci. 2012, 52, 1195) (Saleem, I. Y.; Smyth, H. D. C. AAPS PharmSciTech 2010, 11, 1642), (Takamatsu, H., et al. J. Ceram. Soc. Jpn. 2006, 114, 332), mezclado mecánico (Eyholzer, C, et al. J. Polym. Environ. 2012, 20, 1052), extracción supercrítica (obtención de encapsulados y co-precipitados por extracción de los solventes mediante C02 supercrítico) (Montes, A., et al. The Journal of Supercritical Fluids 2012, 63, 92); son otras de las posibilidades que contempla la bibliografía para la elaboración de nanocompuestos. - Others: Several forms of elaboration of nanocomposites are contemplated physically, normally linked to extrusion, as a previous stage. Grinding (Qian, Z., et al. Polym. Eng. Sci. 2012, 52, 1195) (Saleem, IY; Smyth, HDC AAPS PharmSciTech 2010, 11, 1642), (Takamatsu, H., et al. J. Ceram. Soc. Jpn. 2006, 114, 332), mechanical mixing (Eyholzer, C, et al. J. Polym. Environ. 2012 , 20, 1052), supercritical extraction (obtaining encapsulated and co-precipitated by solvent extraction by supercritical C0 2 ) (Montes, A., et al. The Journal of Supercritical Fluids 2012, 63, 92); These are other possibilities that the bibliography contemplates for the elaboration of nanocomposites.
La investigación en materiales para fabricación aditiva ha tenido concreción industrial en el desarrollo de diversas patentes referidas a procedimientos de fabricación propiamente dichos y para elaboración de los materiales precursores implicados. En concreto, para elaboración de nanocompuestos poliméricos conteniendo grafeno por solución de precursores (Gauthy, F., et al. Solvay SA, Patente WIPO, 2013, N° WO2013127712 (Al)), elastómeros aditivados con nano- arcillas por mezclado mecánico (Ebrahimian, S., et al. AlphaGary Corporation. Patente USPTO, 2004, N° US6797760 (Bl)), poliamidas aditivadas con fílosilicatos mediante extrusión (Presenz, U., Sutter, A. M. EMS-Chemie AG. Patente USPTO, 2005, N° US7442333 (B2)), entre otros contemplados en la bibliografía.  Research in materials for additive manufacturing has had industrial concretion in the development of various patents referring to actual manufacturing procedures and for the preparation of the precursor materials involved. Specifically, for the preparation of polymer nanocomposites containing graphene by solution of precursors (Gauthy, F., et al. Solvay SA, WIPO Patent, 2013, No. WO2013127712 (Al)), elastomers added with nano-clays by mechanical mixing (Ebrahimian , S., et al. AlphaGary Corporation, USPTO Patent, 2004, No. US6797760 (Bl)), polyamides added with phylosilicates by extrusion (Presenz, U., Sutter, AM EMS-Chemie AG. USPTO Patent, 2005, No. US7442333 (B2)), among others contemplated in the bibliography.
La presente invención consiste en la elaboración de un hilo de polímero biodegradable nano-aditivado, por medio de la técnica de extrusión previo recubrimiento mecánico del polímero en molino de bolas. Lo novedoso de la invención planteada estriba en realizar un recubrimiento superficial del polímero con el nanoaditivo, en lugar de perseguirse el perfecto mezclado mecánico o químico, de forma previa a la extrusión. La dispersión se logra por la homogenización que el husillo rotatorio de la máquina correspondiente es capaz de conferirle a la mezcla en caliente del polímero recubierto de nanoaditivo. De esta forma se logra un proceso de elaboración simple, no descrito previamente. DESCRIPCIÓN DE LA INVENCIÓN The present invention consists in the elaboration of a nano-additive biodegradable polymer wire, by means of the extrusion technique prior to mechanical coating of the polymer in a ball mill. The novelty of the proposed invention is to make a surface coating of the polymer with the nanoadditive, instead of pursuing the perfect mechanical or chemical mixing, prior to extrusion. The dispersion is achieved by homogenization that the rotating spindle of the corresponding machine is capable of conferring on the hot mix of the nanoadditive coated polymer. In this way a simple elaboration process is achieved, not previously described. DESCRIPTION OF THE INVENTION
La fabricación aditiva se realiza siguiendo un concepto fabril donde los procesos convencionales para la obtención de piezas para uso industrial y de consumo, basados en distintas técnicas de mecanizado que dan lugar a una fabricación en procesos escalonados, son superados por la obtención de piezas de forma automática y en un solo proceso más rápido y con menores mermas de material. Sin embargo, la implementación a escala industrial de estos nuevos procesos de producción requiere un esfuerzo investigador orientado a minimizar costes de material y equipamiento, de modo que los procesos de fabricación aditiva resulten más rentables que los convencionales. Con lo anterior y lo que se deduce del estado de la técnica descrito en el apartado previo, ese antedicho esfuerzo investigador en materiales de partida para fabricación aditiva queda justificado. Al problema de proporcionar nuevos materiales para fabricación aditiva que mejoren los convencionales, principalmente polímeros puros, pretende dar solución la presente invención.  Additive manufacturing is carried out following a manufacturing concept where the conventional processes for obtaining parts for industrial and consumer use, based on different machining techniques that give rise to a manufacturing in stepped processes, are overcome by obtaining parts in a way automatic and in a single process faster and with lower material losses. However, the industrial scale implementation of these new production processes requires a research effort aimed at minimizing material and equipment costs, so that additive manufacturing processes are more profitable than conventional ones. With the foregoing and what follows from the state of the art described in the previous section, this aforementioned research effort in starting materials for additive manufacturing is justified. The problem of providing new materials for additive manufacturing that improve conventional ones, mainly pure polymers, is intended to solve the present invention.
En este sentido, se ha planteado un procedimiento para elaborar materiales de partida para fabricación aditiva por vía física, consistente en el recubrimiento superficial de gránulos poliméricos por nanoaditivos que mejoren algunas de sus propiedades mecánicas, térmicas, eléctricas y ópticas. En particular, y sin perjuicio de la aplicabilidad del procedimiento que se explica más adelante, se ha trabajado con polímeros biodegradables. Los polímeros biodegradables suman a esta ventaja ambiental el hecho de proceder de fuentes renovables, no vinculadas al consumo de combustibles fósiles. Sin embargo, sus propiedades mecánicas son pobres y, a este respecto, la inclusión de nanoaditivos de diversa naturaleza ha demostrado resultar de interés a la hora de mejorar dichas propiedades, e incluso introducir conductividad eléctrica en un material inicialmente aislante como son los polímeros, entre otras mejoras.  In this sense, a procedure has been proposed to prepare starting materials for additive manufacturing by physical route, consisting of the surface coating of polymeric granules by nanoadditives that improve some of their mechanical, thermal, electrical and optical properties. In particular, and without prejudice to the applicability of the procedure explained below, we have worked with biodegradable polymers. Biodegradable polymers add to this environmental advantage the fact that they come from renewable sources, not linked to the consumption of fossil fuels. However, its mechanical properties are poor and, in this regard, the inclusion of nanoaddives of various kinds has proven to be of interest when it comes to improving these properties, and even introducing electrical conductivity in an initially insulating material such as polymers, among Other improvements
En definitiva, el objeto de la invención es proporcionar una solución al problema de la elaboración de nuevos materiales para fabricación aditiva, aportando materiales nanocompuestos y un procedimiento que permita mayor simplificación técnica que otros aplicados, al tiempo que se ha perseguido la mejora de propiedades de materiales de uso convencional en fabricación aditiva por la inclusión de nanoaditivos, siguiendo el procedimiento de elaboración que describe seguidamente la presente invención. Ultimately, the object of the invention is to provide a solution to the problem of developing new materials for additive manufacturing, providing nanocomposite materials and a procedure that allows greater simplification. technique than others applied, while the improvement of properties of materials of conventional use in additive manufacturing has been pursued by the inclusion of nanoadditives, following the elaboration procedure described below by the present invention.
A la concreción del objeto de la invención se ha ideado un procedimiento para elaborar materiales de partida para fabricación aditiva, consistente en un proceso secuencial en dos etapas que pasa a describirse detalladamente. En primer lugar se realiza un recubrimiento mecánico basado en introducir en un equipo de molienda oportuno, concretamente un molino de bolas planetario, el polímero de partida en forma de granulos y el nanoaditivo correspondiente junto con una carga adecuada de elementos móviles, que procuren el contacto entre el polímero granulado y el nanoaditivo. En segundo lugar, el material así preparado se somete a mezclado en fundido con extrusión para obtenerse un filamento de material nanocompuesto, lográndose la homogenización del nanoaditivo por dispersión a través de la matriz polimérica. A procedure for developing starting materials for additive manufacturing has been devised for the purpose of the invention, consisting of a sequential two-step process that will be described in detail. First, a mechanical coating is carried out based on introducing into a suitable grinding equipment, specifically a planetary ball mill, the starting polymer in the form of granules and the corresponding nanoadditive together with an adequate load of moving elements, which procure the contact between the granulated polymer and the nanoadditive. Secondly, the material thus prepared is subjected to melt mixing with extrusion to obtain a filament of nanocomposite material, achieving homogenization of the nanoadditive by dispersion through the polymer matrix.
El molino de bolas planetario es un equipo consistente en un plato giratorio sobre el que se fija el vaso de molienda, permitiéndosele no obstante el movimiento de rotación (de ahí la denominación planetario: el mecanismo de giro del conjunto plato-vaso de molienda es análogo a la cinemática celeste). El equipo le transmite al recipiente de molienda, o vaso propiamente dicho, una velocidad angular de giro durante un determinado tiempo. Los elementos móviles introducidos en el vaso de molienda, bolas a la sazón, son sometidos a un movimiento aleatorio causado por la propia fuerza centrífuga que el vaso, por estar girando, le confiere a las bolas y sus propias colisiones. De esta manera, el polímero introducido como materia particulada de granulometría milimétrica (pellets) es sometido a múltiples colisiones contra las bolas y paredes del vaso de molienda, produciéndose el recubrimiento superficial a través de este mecanismo, toda vez que el nanoaditivo se ha introducido como carga al vaso.  The planetary ball mill is a team consisting of a turntable on which the grinding vessel is fixed, however allowing the rotation movement (hence the planetary designation: the turning mechanism of the grinding plate-glass assembly is similar to celestial kinematics). The equipment transmits to the grinding vessel, or glass itself, an angular speed of rotation during a certain time. The mobile elements introduced into the grinding vessel, balls at the time, are subjected to a random movement caused by the centrifugal force itself that the glass, by turning, confers on the balls and their own collisions. In this way, the polymer introduced as particulate matter of millimeter granulometry (pellets) is subjected to multiple collisions against the balls and walls of the grinding vessel, the surface coating being produced through this mechanism, since the nanoadditive has been introduced as Load the glass.
De acuerdo a lo descrito previamente, es fundamental determinar las variables de operación para elaborar un producto final con las mejores propiedades posibles. La extrusión es un proceso convencional en la producción de materiales para fabricación aditiva, por lo que lo novedoso en la presente invención consiste en recubrir pellets de material polimérico con el nanoaditivo, mediante el proceso de molienda descrito, como paso previo al citado mezclado en rundido con extrusión. En concreto, las variables de operación para la molienda serán la carga y tipo de bolas, carga de material (polímero y nanoaditivo) al vaso, tiempo del recubrimiento y velocidad angular de giro del plato del molino. As previously described, it is essential to determine the operating variables to produce a final product with the best possible properties. Extrusion is a conventional process in the production of materials for additive manufacturing, so the novel thing in the present invention consists in coating pellets of polymeric material with the nanoadditive, by means of the grinding process described, as a previous step to the said one mixed in rounded with extrusion. Specifically, the operation variables for grinding will be the loading and type of balls, loading of material (polymer and nanoadditive) to the vessel, coating time and angular speed of rotation of the mill plate.
Se ha empleado un vaso de molienda de óxido de Y-Zr, una cerámica de alta resistencia al impacto y la abrasión y bolas de lo mismo. En general, cuando se desea minimizar la granulometría de las partículas de carga a la molienda debe utilizarse bolas del menor tamaño posible. Puesto que no se desea la reducción de los pellets (y además no es posible dado su comportamiento mecánico eminentemente plástico) sino sólo el recubrimiento superficial con el nanoaditivo, se ha optado por emplear las bolas de mayor tamaño disponibles. Concretamente se ha empleado un juego de 25 bolas de 20 mm 0. Conocida y fijada la carga de bolas es preciso determinar la carga recomendable de material al vaso. Si se carga polímero en exceso se minimizará la libertad de colisiones y con ello el grado de recubrimiento; caso contrario, el defecto de carga supondrá la deformación de los pellets por aumento del número de colisiones. Siguiendo recomendaciones técnicas del equipo las cargas de polímero y nanoaditivo deberán estar comprendidas entre 65-180 g. Finalmente, una velocidad angular del plato de molienda excesiva conlleva, por aumento del número de colisiones, la deformación de los pellets por lo que deberá llegarse a una relación de compromiso de máxima velocidad angular para menor tiempo de proceso.  A Y-Zr oxide grinding vessel, a ceramic with high impact and abrasion resistance and balls thereof has been used. In general, when it is desired to minimize the particle size of the grinding filler particles, balls of the smallest possible size should be used. Since the reduction of the pellets is not desired (and in addition it is not possible given its eminently plastic mechanical behavior) but only the surface coating with the nanoadditive, it has been decided to use the largest available balls. Specifically, a set of 25 balls of 20 mm 0 has been used. Once the ball load is known and fixed, it is necessary to determine the recommended material load to the vessel. If polymer is loaded in excess, the collision freedom will be minimized and thus the degree of coating; Otherwise, the load defect will involve the deformation of the pellets due to an increase in the number of collisions. Following technical recommendations of the equipment, polymer and nanoadditive loads should be between 65-180 g. Finally, an angular speed of the excessive grinding plate entails, due to an increase in the number of collisions, the deformation of the pellets, so that a maximum angular velocity engagement ratio must be reached for less process time.
En el contexto de la presente invención, el procedimiento descrito ha sido empleado y demostrada su utilidad para la elaboración de distintos materiales para fabricación aditiva. Entre otros, se han recubierto pellets de plásticos biodegradables tipo PLA/PHA (del inglés Polylactic acid/Polyhydroxyalkanoate) y de PLA con nanoaditivos tales como láminas de grafito de espesor nanométrico, GNP, (del inglés Graphite Nano-Platelets) y nanopartículas funcionalizadas de Ag, Au y otros metales preciosos, para favorecer la excitación de plasmones superficiales a nanoescala. En efecto, la interacción de los plasmones, u oscilaciones cuantizadas de densidad del plasma de electrones libres de los metales, con los fotones o cuantos de luz da lugar a cambios ópticos en los materiales poliméricos por la emisión en un determinado rango del espectro visible. In the context of the present invention, the described process has been used and proven useful for the preparation of different materials for additive manufacturing. Among others, pellets of biodegradable plastics type PLA / PHA (of English Polylactic acid / Polyhydroxyalkanoate) and of PLA have been coated with nanoadditives such as graphite sheets of nanometric thickness, GNP (of English Graphite Nano-Platelets) and functionalized nanoparticles of Ag, Au and other precious metals, to favor the excitation of surface plasmons at nanoscale. Indeed, the interaction of plasmons, or quantized oscillations of plasma density of free electrons of metals, with photons or quanta of light gives rise to optical changes in polymeric materials by emission in a certain range of the visible spectrum.
La aplicación del proceso de recubrimiento para los materiales descritos ha proporcionado resultados satisfactorios, a tenor de lo observado por microscopía electrónica de barrido y microscopía de haces de iones focalizados: se observan secciones transversales de pellets donde se constata el recubrimiento superficial por la ausencia de los nanoaditivos en el núcleo polimérico.  The application of the coating process for the described materials has provided satisfactory results, according to what was observed by scanning electron microscopy and focused ion beam microscopy: cross sections of pellets are observed where the surface coating is verified by the absence of the nanoadditives in the polymer core.
Como parte de lo reivindicado en la presente invención, desea hacerse hincapié en la elaboración de PLA/PHA nanoaditivado con GNP. Se ha preparado mediante el procedimiento de elaboración descrito, por recubrimiento mecánico seguido de mezclado en fundido con extrusión, para obtenerse un filamento de material nanocompuesto con una homogénea dispersión del nanoaditivo en la matriz polimérica. Este material ha sido de aplicación en fabricación aditiva, concretamente mediante modelado por deposición de rundido. La determinación de propiedades térmicas ha confirmado la no degradación del polímero a la temperatura de trabajo de la máquina de fabricación aditiva antedicha. Este hecho, junto con la medición y verificación de las propiedades mecánicas, que han mejorado tanto en régimen elástico como en régimen plástico las propiedades del PLA puro convencional, convierten al filamento basado en PLA/PHA-GNP en un prometedor material para la fabricación mediante síntesis aditiva. Lo explicado se hace extensivo, de forma análoga, a otros nanocomposites involucrando los mismos u otros polímeros y otros nanoaditivos, como los mencionados con comportamiento plasmónico superficial a nanoescala incluyendo nanopartículas de metales (plata, oro u otros metales cuyos plasmones superficiales hacen posible la absorción de la luz con la energía necesaria cuando ésta incide sobre dichos metales con dimensiones a nanoescala). A estos últimos filamentos nanoaditivados con nanopartículas metálicas con el comportamiento plasmónico indicado se les denominará "filamentos plasmónicos". As part of what is claimed in the present invention, it is desired to emphasize the elaboration of PLA / PHA nano-additive with GNP. It has been prepared by the described manufacturing process, by mechanical coating followed by melt mixing with extrusion, to obtain a filament of nanocomposite material with a homogeneous dispersion of the nanoadditive in the polymer matrix. This material has been applied in additive manufacturing, specifically by modeling by deposition of rounded. The determination of thermal properties has confirmed the non-degradation of the polymer at the working temperature of the aforementioned additive manufacturing machine. This fact, together with the measurement and verification of the mechanical properties, which have improved both the elastic and the plastic regime the properties of conventional pure PLA, make the filament based on PLA / PHA-GNP a promising material for manufacturing by additive synthesis The above is extended, analogously, to other nanocomposites involving the same or other polymers and other nanoadditives, such as those mentioned with surface plasmonic behavior at nanoscale including metal nanoparticles (silver, gold or other metals whose surface plasmons make absorption possible of the light with the necessary energy when it affects these metals with nanoscale dimensions). To these last filaments Nano-additives with metallic nanoparticles with the indicated plasmonic behavior will be called "plasmonic filaments".
MODO DE REALIZACIÓN DE LA INVENCIÓN EMBODIMENT OF THE INVENTION
La elaboración de material a que se refiere la presente invención podrá llevarse a efecto siguiendo la secuencia que se desarrolla seguidamente. The preparation of material referred to in the present invention may be carried out in the sequence that follows.
1. Se introducirán en el vaso de molienda los pesos correspondientes a la carga de polímero y nanoaditivo junto con las bolas en las magnitudes indicadas en la descripción de la invención. Deberá ajustarse la carga de nanoaditivo al porcentaje en peso de polímero que se desee.  1. The weights corresponding to the polymer and nanoadditive load together with the balls in the quantities indicated in the description of the invention shall be introduced into the grinding vessel. The nanoadditive load should be adjusted to the desired weight percentage of polymer.
2. Seguidamente, deberá fijarse el vaso de molienda al plato del molino de bolas planetario correspondiente y, una vez asegurado, fijar las condiciones de velocidad angular del plato y tiempo de molienda.  2. Next, the grinding vessel must be fixed to the plate of the corresponding planetary ball mill and, once secured, set the conditions for angular plate speed and grinding time.
3. Transcurrido el tiempo de molienda deberá separarse las bolas del polímero recubierto después del paso anterior y recoger el segundo como material preparado para el mezclado en fundido con extrusión.  3. After the grinding time has elapsed, the balls must be separated from the coated polymer after the previous step and the second one must be collected as material prepared for extrusion melt mixing.
4. La carga de pellets se introduce en la tolva de carga de una extrusora cuyo husillo girará a una velocidad determinada forzando al polímero a atravesar el cuerpo dividido en secciones calefactadas de la misma. La máquina extrusora concluye en una boquilla de pequeño diámetro a través de la que el polímero fluirá formando un hilo.  4. The loading of pellets is introduced into the loading hopper of an extruder whose spindle will rotate at a certain speed forcing the polymer to pass through the body divided into heated sections thereof. The extruder machine concludes in a small diameter nozzle through which the polymer will flow forming a thread.
5. El hilo del paso cuarto debe enfriarse para su solidificación en un baño de agua dispuesto a la salida del equipo de extrusión. Finalmente el filamento así formado se recoge y se bobina convenientemente, quedando preparado para su disposición en máquinas de fabricación aditiva de modelado por deposición de fundido. Un ejemplo de elaboración es el que sigue: 130 g de PLA junto con un 0,1% p/p de GNP, colocados junto a 25 bolas de 20 mm 0 de óxido de Y-Zr en un vaso de molienda comercial de un molino de bolas planetario Retsch modelo PM100. Esta carga se agita en el molino durante 15 min a 350 rpm lográndose el recubrimiento superficial de los pellets de PLA por el GNP. Este material se inyecta en una extrusora con una velocidad de giro del husillo de 50 rpm y las secciones calefactadas con temperaturas oscilando los 160-180 °C, para obtenerse un filamento de diámetro constante de 1,75 mm. 5. The thread of the fourth step must be cooled for solidification in a water bath arranged at the exit of the extrusion equipment. Finally, the filament thus formed is collected and coiled conveniently, being prepared for disposal in machines for additive manufacturing of molten deposition modeling. An example of elaboration is as follows: 130 g of PLA together with 0.1% w / w of GNP, placed next to 25 balls of 20 mm 0 of Y-Zr oxide in a commercial grinding glass of a mill Retsch planetary ball model PM100. This load is stirred in the mill for 15 min at 350 rpm, achieving the surface coating of the PLA pellets by the GNP. This material is injected into an extruder with a spindle rotation speed of 50 rpm and heated sections with temperatures ranging from 160-180 ° C, to obtain a constant diameter filament of 1.75 mm.
APLICACIÓN INDUSTRIAL INDUSTRIAL APPLICATION
La invención incluye un procedimiento para la elaboración de filamentos de materiales nanocompuestos para fabricación aditiva así como algunas de las formulaciones descritas y reivindicadas. El objeto de aplicación industrial propiamente dicho es el filamento, que es el material de partida para máquinas de modelado por deposición de fundido, FDM.  The invention includes a process for the preparation of filaments of nanocomposite materials for additive manufacturing as well as some of the formulations described and claimed. The object of industrial application itself is the filament, which is the starting material for molten deposition modeling machines, FDM.
Una vez demostrada la mejora de las propiedades mecánicas, respecto a materiales poliméricos convencionales para fabricación aditiva, por parte de los materiales desarrollados a partir del procedimiento objeto de la presente invención, el interés de este material estará vinculado al desarrollo de las técnicas de fabricación aditiva y su implantación a escala industrial, como queda indicado en el estado de la técnica.  Once the improvement of the mechanical properties has been demonstrated, with respect to conventional polymeric materials for additive manufacturing, by the materials developed from the process object of the present invention, the interest of this material will be linked to the development of additive manufacturing techniques and its implementation on an industrial scale, as indicated in the prior art.
Con vistas a dicha implementación del proceso de fabricación aditiva por FDM, también el procedimiento para la elaboración de filamentos deberá ser escalado al objeto de alcanzarse una producción de materiales de partida acorde a las necesidades de una eventual empresa desarrollada a partir de las tecnologías descritas en la presente invención.  With a view to the implementation of the additive manufacturing process by FDM, the procedure for the manufacture of filaments must also be scaled in order to achieve a production of starting materials according to the needs of an eventual company developed from the technologies described in The present invention.

Claims

REIVINDICACIONES
1. Procedimiento de elaboración de materiales de partida para fabricación aditiva que comprende la realización secuencial de las siguientes etapas: a) Recubrimiento superficial de granulos poliméricos con nanoaditivos, mediante un procedimiento mecánico.  1. Process for preparing starting materials for additive manufacturing comprising the sequential realization of the following steps: a) Surface coating of polymer granules with nanoadditives, by means of a mechanical process.
b) Mezclado en fundido con posterior extrusión.  b) Mixed in melt with subsequent extrusion.
Procedimiento de elaboración de materiales de partida para fabricación aditiva, según reivindicación 1, caracterizado porque el recubrimiento superficial de los granulos poliméricos con nanoaditivos se realiza introduciendo ambos componentes en un equipo de molienda. Process for preparing starting materials for additive manufacturing, according to claim 1, characterized in that the surface coating of the polymer granules with nanoadditives is carried out by introducing both components into a grinding equipment.
Procedimiento de elaboración de materiales de partida para fabricación aditiva, según reivindicación 2, caracterizado porque el recubrimiento superficial de los granulos poliméricos con nanoaditivos se realiza introduciendo ambos componentes en un molino planetario de bolas. Process for preparing starting materials for additive manufacturing, according to claim 2, characterized in that the surface coating of the polymer granules with nanoadditives is carried out by introducing both components into a planetary ball mill.
Procedimiento de elaboración de materiales de partida para fabricación aditiva, según reivindicación 3, caracterizado porque el recubrimiento superficial de los granulos poliméricos con nanoaditivos se realiza sobre masas de polímero comprendidos entre 65-180 g, en un vaso de molienda de óxido de Y-Zr con 25 bolas del mismo material de 20 mm 0. Process for preparing starting materials for additive manufacturing, according to claim 3, characterized in that the surface coating of the polymer granules with nanoadditives is carried out on polymer masses between 65-180 g, in a Y-Zr oxide grinding vessel with 25 balls of the same material of 20 mm 0.
Procedimiento de elaboración de materiales de partida para fabricación aditiva, según reivindicaciones 1 a 4, donde los gránulos poliméricos son polímeros biodegradables. Process for preparing starting materials for additive manufacturing, according to claims 1 to 4, wherein the polymer granules are biodegradable polymers.
6. Procedimiento de elaboración de materiales de partida para fabricación aditiva, según reivindicación 5, donde los gránulos poliméricos son del tipo PLA/PHA o PLA puro. 6. Process for preparing starting materials for additive manufacturing, according to claim 5, wherein the polymer granules are of the type PLA / PHA or pure PLA.
7. Procedimiento de elaboración de materiales de partida para fabricación aditiva, según reivindicaciones 1 a 4, donde los nanoaditivos empleados son láminas de grafito de espesor nanométrico (GNP). 7. Process for preparing starting materials for additive manufacturing, according to claims 1 to 4, wherein the nanoadditives used are graphite sheets of nanometric thickness (GNP).
8. Procedimiento de elaboración de materiales de partida para fabricación aditiva, según reivindicaciones 1 a 4, donde los nanoaditivos empleados son nanopartículas funcional izadas de metales con comportamiento plasmónico superficial a nanoescala. 8. Process for the preparation of starting materials for additive manufacturing, according to claims 1 to 4, wherein the nanoadditives used are functional nanoparticles of metals with nanoscale surface plasmonic behavior.
9. Procedimiento de elaboración de materiales de partida para fabricación aditiva, según reivindicación 8, donde los nanoaditivos empleados son nanopartículas de plata funcionalizadas con comportamiento plasmónico superficial a nanoescala. 9. Process for preparing starting materials for additive manufacturing, according to claim 8, wherein the nanoadditives used are functionalized silver nanoparticles with nanoscale surface plasmonic behavior.
10. Procedimiento de elaboración de materiales de partida para fabricación aditiva, según reivindicación 8, donde los nanoaditivos empleados son nanopartículas de oro funcionalizadas con comportamiento plasmónico superficial a nanoescala. 10. Process for preparing starting materials for additive manufacturing, according to claim 8, wherein the nanoadditives used are functionalized gold nanoparticles with nanoscale surface plasmonic behavior.
11. Filamentos poliméricos nanoaditivados elaborados según reivindicaciones 1 a 7. 11. Nano-additive polymeric filaments made according to claims 1 to 7.
12. Filamentos poliméricos nanoaditivados elaborados según reivindicaciones 8 a 10, que por su comportamiento plasmónico superficial a nanoescala reciben la denominación de "filamentos plasmónicos". 12. Nano-additive polymeric filaments made according to claims 8 to 10, which due to their surface plasmonic behavior at nanoscale are called "plasmonic filaments".
13. Uso de los filamentos, según reivindicaciones 11 y 12, en fabricación aditiva mediante máquinas de modelado por deposición de fundido. 13. Use of the filaments, according to claims 11 and 12, in additive manufacturing by means of melt deposition modeling machines.
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