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WO2023023207A1 - Formulations de photopolymère diélectrique thermoconducteur compatibles avec la fabrication additive par polymérisation en cuve - Google Patents

Formulations de photopolymère diélectrique thermoconducteur compatibles avec la fabrication additive par polymérisation en cuve Download PDF

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Publication number
WO2023023207A1
WO2023023207A1 PCT/US2022/040671 US2022040671W WO2023023207A1 WO 2023023207 A1 WO2023023207 A1 WO 2023023207A1 US 2022040671 W US2022040671 W US 2022040671W WO 2023023207 A1 WO2023023207 A1 WO 2023023207A1
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WIPO (PCT)
Prior art keywords
flakes
approximately
range
resin
vol
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PCT/US2022/040671
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English (en)
Inventor
Randall M. Erb
Kyle J. JOHNSON
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3Dfortify Inc.
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Publication of WO2023023207A1 publication Critical patent/WO2023023207A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
    • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y70/00—Materials specially adapted for additive manufacturing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y80/00—Products made by additive manufacturing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/02—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances
    • H01B3/12—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances ceramics
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances

Definitions

  • the present disclosure relates to vat photopolymerization additive manufacturing, including for both stereolithography (SLA) and digital light processing (DLP) style printing, and more particularly relates to the use of thermally conductive dielectric photopolymer formulations that can be used in conjunction with the same.
  • SLA stereolithography
  • DLP digital light processing
  • Thermally conductive materials conduct heat using phonons and/or electrons to transport energy. Many materials traditionally used in thermally conductive applications leverage both phonons and electrons to conduct heat. However, heat conduction through electron transport prohibits these materials from use in dielectric applications. Dielectric ceramic materials are a solution that provide thermal conductivity in the absence of electrical conduction.
  • dielectric ceramic materials suffer from particularly difficult processing, at least due to the high temperatures required, and also from brittle mechanical properties. These restrictions limit the complexity and functionality of parts manufactured out of these materials. Additive manufacturing provides a solution in this space both through selective laser sintering (which are subsequently post-processed like traditional ceramics) as well as through the incorporation of dielectric ceramic particles into a polymer matrix, which can form a composite.
  • Thermally conductive dielectric composite materials for additive manufacturing have been developed with a primary emphasis on extrusion-based technologies (e.g, direct ink writing (DIW), fused filament fabrication (FFF), fused deposition modeling (FDM), etc.) Attorney Docket No.: 3DF-009 PCT
  • Vat photopolymerization offers a solution to the shortcomings of extrusion-based technologies by filling photopolymer resin with thermally conductive dielectric ceramic particles. The addition of ceramic particles can scatter light beyond the desired print regions and increases resin viscosity which reduces printability.
  • the present disclosure generally relates to a conductive and dielectric photopolymer resin filled with ceramic particles.
  • This resin can be carefully tailored to effectively manage challenges with photokinetics and rheology that have so far prevented such systems from being implemented in vat photopolymerization 3D printing.
  • specially selected combinations of crystalline ceramics can be selected that transport heat through coordinated atomic vibrations, called phonons, instead of through electron transport, which also creates electrical conduction. Combining these phononic-crystals at high filler amounts can create a percolated network within the resin that allows for the rare combination of high thermal conductivity and high dielectric strength.
  • the combination of crystalline ceramics can increase thermal conductivity but also reduce the viscosity of these highly-filled systems and reduce photokinetic challenges like scattering.
  • Modified anisotropic ceramic particles of different select sizes, shapes/ and/or optical properties enable thermal conductivity while providing dimensional accuracy and printability.
  • the thermally conductive dielectric photopolymer resin of the present embodiments can be used to print complex geometries that would not be possible through traditional manufacturing, with the parts exhibiting functionality not possible through other forms of polymer additive manufacturing.
  • an additive manufacturing apparatus includes a photopolymer resin and a ceramic particle filler.
  • the ceramic particle filler includes at least two of the following: a first set of anisotropic particles in a non-agglomerated state and having a particle size of the major axis of the first set of anisotropic particle being approximately in a range of about 20 pm to about 75 pm; an aggregate of particles having a particle size of the major axis of the aggregate of particles being approximately in a range of about 15 pm to about 30 pm; and a third set of anisotropic particles in a non-agglomerated state, with a particle size of the major axis of the third set of anisotropic particles being approximately in a range of about 150 nm to about 8000 nm.
  • the first set of anisotropic particles can include monocry stalline boron nitride platelets in approximately a range of about 10 vol% to about 20 vol%.
  • the aggregate of particles can include boron nitride aggregates in approximately a range of about 5 vol% to about 15 vol%.
  • the third set of anisotropic particles can include aluminum nitride platelets in approximately a range of about 5 vol% to about 10 vol%.
  • one or more of the first set and third set of anisotropic particles and the aggregate of particles can include hexagonal boron nitride.
  • one or more of the first set of anisotropic particles, the aggregate of particles, the third set of anisotropic particles, or the photopolymer resin can be configured to be at least one of physically or chemically labeled with UV-adsorbing material.
  • a total volume fraction of the ceramic filler can be approximately in a range of about 20 vol% to about 60 vol%.
  • a viscosity of the composition can be approximately in a range of about 1000 cP to about 250,000 cP.
  • a thermal conductivity of the composition is approximately in a range of about 1 W/m*K to about 10 W/m*K.
  • One exemplary thermally conductive dielectric resin composition includes a mixture of flakes and a photopolymer resin.
  • the mixture of flakes includes a first set of flakes in a non-agglomerated state, a second agglomerate of flakes, and a third set of flakes in a nonagglomerated state.
  • a size of the major axis of the first set of flakes is larger than a size of the major axis of the second agglomerate of flakes, and the size of the major axis of the second agglomerate of flakes is larger than a size of the major axis of the third set of flakes.
  • a thermal conductivity of the thermally conductive dielectric photopolymer resin is approximately in a range of about 1 W/m*K to about 10 W/m*K.
  • the first set of flakes can include anisotropic flakes with the size of the major axis of the first set of flakes being approximately in a range of about 20 pm to about 75 pm.
  • the second agglomerate of flakes can include flakes that are more isotropic than the first set of flakes with the size of the major axis of the second agglomerate of flakes being approximately in a range of about 15 pm to about 30 pm.
  • the second agglomerate of flakes can include hBN aggregates and AIN aggregates.
  • the third set of flakes can include anisotropic flakes with the size of the major axis of the third set of flakes being approximately in a range of about 150 nm to about 8000 nm.
  • a viscosity of the thermally conductive dielectric photopolymer resin can be approximately in a range of about 1,000 cP to about 250,000 cP.
  • the thermally conductive dielectric photopolymer resin can have a dielectric strength approximately in a range of about 20 kV/mm to about 40 kV/mm or an electrical resistivity approximately in the range of about 10 12 ohm-cm to about IO 20 ohm-cm.
  • One exemplary method of producing an object having high thermal conductivity and low electrical conductivity by additive manufacturing includes depositing a photopolymer resin having a thermal conductivity approximately in a range of about 1 W/m*K to about 10 W/m*K to form a layer of a three-dimensional object. The method also includes depositing the photopolymer resin to form one or more additional layers of the three- dimensional object.
  • An electrical resistivity of the three-dimensional object is approximately in a range of about 10 12 ohm-cm to about IO 20 ohm-cm.
  • the actions of depositing a photopolymer resin having a thermal conductivity approximately in a range of about 1 W/m*K to about 10 W/m*K to form a layer of a three-dimensional object and depositing the photopolymer resin to form one or more additional layers of the three-dimensional object can include depositing the photopolymer resin from a vat of the photopolymer resin.
  • the actions of depositing a photopolymer resin having a thermal conductivity approximately in a range of about 1 W/m*K to about 10 W/m*K to form a layer of a three-dimensional object and depositing the photopolymer resin to form one or more additional layers of the three- dimensional object can occur via vat polymerization.
  • the additive manufacturing performed in accordance with this method can be not fused deposition modeling (FDM).
  • FDM fused deposition modeling
  • the photopolymer resin can further include a first set of anisotropic particles in a non-agglomerated state, a second set of particles in an agglomerated state, and a third set of anisotropic particles in a non-agglomerated state.
  • the first set of particles can have a particle size of the major axis of that is approximately in a range of about 35 pm to about 60 pm.
  • the second set of particles can be more isotropic than the first set of anisotropic particles and can have a particle size of the major axis that is approximately in a range of about 15 pm to about 30 pm.
  • the third set of anisotropic particles can have a particle size of the major axis that is approximately in a range of about 150 nm to about 8000 nm.
  • a viscosity of the photopolymer resin can be approximately in a range of about 1000 cP to about 250,000 cP.
  • One exemplary method of forming a polymer matrix composite for use in additive manufacturing includes combining at least two of: a first set of flakes in a non-agglomerated state, a second agglomerate of flakes, or a third set of flakes in a non-agglomerated state.
  • the method further includes drying the combination of the at least two of the first set of flakes, the second agglomerate of flakes, or the third set of flakes, and combining the dried combination with a high-performance resin and a lower viscosity monomer to form a thermally conductive dielectric resin.
  • the first set of flakes When the first set of flakes is present, they are anisotropic.
  • the third set of flakes is present, they are anisotropic.
  • the second agglomerate of flakes When the second agglomerate of flakes is present, they are more isotropic than the first set of flakes and/or the third set of flakes.
  • the first set of flakes can be approximately in a range of about 10 vol% to about 20 vol%
  • the second agglomerate of flakes can be approximately in a range of about 5 vol% to about 15 vol%
  • the third set of flakes can be approximately in a range of about 5 vol% to about 10 vol%.
  • a total volume fraction of the polymer matrix composite can be approximately in a range of about 20 vol% to about 60 vol%.
  • the first set of flakes can have a size of the major axis approximately in a range of about 20 pm to about 75 pm
  • the second agglomerate of flakes can have a size of the major axis approximately in a range of about 15 pm to about 30 pm
  • the third set of flakes can have a size of the major axis approximately in a range of about 150 nm to about 3000 nm.
  • the high-performance resin and the lower viscosity monomer can be combined prior to combining them with the dried combination.
  • the method can further include magnetizing the first set of flakes through physisorption of superparamagnetic iron oxide nanoparticles (SPIONs). At least one of a dye or a pigment can be combined with the dried combination, the high- performance resin, and the lower viscosity monomer to provide photoadsorption. In some embodiments, the method can further include at least one of physically or chemically labeling one or more of the first set of flakes, the second agglomerate of flakes, or the third set of flakes with UV adsorbing material.
  • SPIONs superparamagnetic iron oxide nanoparticles
  • One exemplary method of forming a polymer matrix composite for use in additive manufacturing includes magnetizing a first set of flakes in a non-agglomerated state, combining the magnetized first set of flakes with a second set of flakes in a nonagglomerated state, drying the combination of first and second sets of flakes, and combining the dried combination with a high-performance resin and a lower viscosity monomer to form a thermally conductive dielectric resin.
  • the first and third sets of flakes are anisotropic.
  • magnetizing a first set of flakes in a non-agglomerated state can further include using physisorption of superparamagnetic iron oxide nanoparticles in conjunction with the same.
  • At least one of a dye or a pigment can be combined with the dried combination, the high-performance resin, and the lower viscosity monomer to provide photoadsorption.
  • the high-performance resin and the lower viscosity monomer can be combined prior to combining them with the dried combination.
  • FIG. 1A is a schematic side view of one embodiment of a photopolymer matrix of the ceramic particle filler of the present disclosure showing various crystals therein;
  • FIG. IB is a top perspective view of large phononic crystals of the photopolymer matrix of FIG. 1A;
  • FIG. 1C is a perspective view of medium phononic crystals of the photopolymer matrix of FIG. 1A; Attorney Docket No.: 3DF-009 PCT
  • FIG. ID is a top perspective view of small phononic crystals of the photopolymer matrix of FIG. 1A;
  • FIG. 2 is a graph illustrating viscosity versus volume fraction of particles for resins having crystals of one size, of two sizes, and of three sizes;
  • FIG. 3 A is a perspective view of one embodiment of a printing apparatus
  • FIG. 3B is a side view of the printing apparatus of FIG. 3 A having a side panel of a housing removed to illustrate components of the printing apparatus disposed within the housing;
  • FIG. 4 is a schematic side view of the photopolymer matrix of FIG. 1A disposed between a build plate and a transparent membrane of the printing apparatus of FIG. 3 A;
  • FIG. 5 is one embodiment of a method for manufacturing resin of the present disclosure
  • FIG. 6 is another embodiment of a method for manufacturing resin of the present disclosure
  • FIG. 7 is still another embodiment of a method for manufacturing resin of the present disclosure.
  • FIG. 8A is a graph illustrating electrical resistivity values and thermal conductivity values for resin of the present disclosure and for other materials
  • FIG. 8B is a perspective view of an embodiment of a heat exchanger printed using the resin of the present embodiments.
  • FIG. 8C is an infrared image providing side views of the heat exchanger of FIG. 8B and a conventional heat exchanger to illustrate heat conduction by each;
  • FIG. 9 is a perspective view of an example of a tube heat exchanger that can be printed using the resin of the present embodiments.
  • FIG. 10 is a perspective view of an example of a heat sink that can be printed using the resin of the present embodiments; Attorney Docket No.: 3DF-009 PCT
  • FIG. 11 is a top perspective view of an example of a cold plate that can be printed using the resin of the present embodiments
  • FIG. 12 is a perspective view of an example of an electric vehicle (EV) charging port that can be printed using the resin of the present embodiments.
  • EV electric vehicle
  • FIG. 13 is a top view view of an example of a battery terminal encapsulant that can be printed using the resin of the present embodiments.
  • the terms “flakes,” “crystals,” “platelets,” and “particles” can be used interchangeably herein to refer to individual components of each of the large, medium, and small sized compounds of the ceramic filler.
  • the terms “flakes,” “crystals,” “platelets,” and “particles” can be used interchangeably herein to refer to individual components of each of the large, medium, and small sized compounds of the ceramic filler.
  • the present disclosure provides for printing of thermally conductive dielectric materials, with the materials and subsequent iterations thereof being implemented in thermal applications where additive manufacturing can be leveraged.
  • the present disclosure generally relates to a thermally conductive dielectric photopolymer resin (abbreviated as TCDR) that is compatible with vat photopolymerization additive manufacturing.
  • the thermally conductive dielectric photopolymer resin can include a photopolymer resin combined with a ceramic filler.
  • the filler can include anisotropic, phononic crystals that can facilitate high thermal conductivity and percolation at lower particle concentrations than is possible with isotropic fillers.
  • the phononic crystals can include large, medium, and small crystals to achieve a reduction in resin viscosity when the filler concentration is held constant and a higher particle loading than possible with a single particle size such that a high thermal conductivity and usability of the resin during printing is maintained.
  • the thermally conductive dielectric photopolymer resin incorporates fillers of different particle sizes and dispersion states (e.g, agglomerated, nonagglomerated) to reduce the viscosity of the thermally conductive dielectric photopolymer resin to a value suitable for printing.
  • FIGS. 1A-1D illustrate one embodiment of a photopolymer matrix 100 of the thermally conductive dielectric photopolymer resin of the present embodiments.
  • the photopolymer matrix 100 can include a photopolymer resin combined with a ceramic filler to form the thermally conductive dielectric photopolymer resin.
  • the ceramic filler can incorporate one or more sets of phononic crystals 102 therein.
  • the crystals 102 of the ceramic filler can be different sizes to allow for high particle loading to achieve high thermal conductivity while maintaining printability of the resin of the present embodiments. For example, as shown in FIG.
  • the photopolymer matrix 100 can include large crystals 104, Attorney Docket No.: 3DF-009 PCT
  • large crystals 104 can include crystals or platelets having a particle size of the major axis that is approximately in a range of about 20 pm to about 75 pm, or approximately in a range of about 30 pm to about 65 pm, or approximately in a range of about 35 pm to about 60 pm, and/or approximately in a range of about 40 pm to about 50 pm.
  • medium crystals, or aggregates of platelets or crystals, 106 can include crystals having a particle size of the major axis that is approximately in a range of about 10 pm to about 30 pm, or approximately in a range of about 15 pm to about 30 pm, and/or approximately in a range of about 20 pm to about 25 pm.
  • the term “medium crystals” can be used to describe aggregates of platelets, crystals, and/or flakes that form agglomerates of the above-mentioned size in the photopolymer matrix 100 of the present embodiments.
  • small crystals 108 can include crystals having a particle size of the major axis that is approximately in a range of about 150 nm to about 8000 nm, or approximately in a range of about 300 nm to about 5000 nm, or approximately in a range of about 500 nm to about 2000 nm, and/or approximately in a range of about 600 nm to about 1200 nm.
  • the particle size of the major axis of the medium crystals 106 can be approximately in the range of about 5% to about 60% of the particle size of the major axis of the large crystals 104 and the particle size of the major axis of the small crystals 108 can be approximately in the range of about 2% to about 20% of the particle size of the major axis of the medium crystals 106, although other values are possible (e.g, about 5%, about 10%, about 15%, about 20%, about 25%). Further, the difference in size between the medium and large crystals and the medium and small crystals does not have to equal.
  • the ceramic filler of the present embodiments can include large crystals 104 and medium crystals 106, though, in alternate embodiments, the ceramic filler can include one or more of large crystals 104 and small crystals 108, medium crystals 106 and small crystals 108, and/or large crystals 104, medium crystals 106, and small crystals 108.
  • large crystals 104 and small crystals 108 can include one or more of large crystals 104 and small crystals 108, medium crystals 106 and small crystals 108, and/or large crystals 104, medium crystals 106, and small crystals 108.
  • size of the crystals is discussed in terms of a measurement with respect to the major axis thereof, size can also be measured by diameter, radius, and similar terms used to measure distances across various geometric shapes.
  • the phononic crystals 102 can include hexagonal boron nitride (hBN) and hexagonal aluminum nitride (hAlN), though in some embodiments, the crystals can include diamond, molybdenum disulfide, graphene, silicon carbide, tungsten carbide, and/or silicon nitride.
  • the large crystals 104 and medium crystals 106 can comprise Attorney Docket No.: 3DF-009 PCT
  • the medium crystals 106 and/or the large crystals 104 can include powders comprised of standard phononic crystal flakes, loosely agglomerated powders of phononic crystal flakes, spherical agglomerated powders of phononic crystal flakes, and/or high density blocky-shaped agglomerated powders of phononic crystal flakes.
  • the medium crystals 106 and/or the large crystals 104 can include aggregated structures of hBN flakes exhibiting decreased anisotropy relative to individual hBN flakes.
  • the phononic crystals 102 can include different dispersion states that can form a percolated network within the photopolymer matrix 100 of the thermally conductive dielectric photopolymer resin.
  • the matrix 100 can include a first set of single crystal non-agglomerated particles 104, e.g., large particles, a second set of substantially isotropic agglomerates or particles 106, e.g., medium particles, and a third set of anisotropic particles in a substantially non-agglomerated state 108, e.g., small particles.
  • the use of particles of various dispersion states can improve the percolation of the phononic crystals 102 and can help overcome resulting substantial increases in viscosity that can cause the resin to become unsuitable for printing, as discussed in greater detail below.
  • the base of the percolated network can be the large crystals 104, or platelets of boron nitride in some instances, which can be highly anisotropic.
  • the large crystals 104 can be monocry stalline hexagonal boron nitride platelets.
  • the thermal conductivity of the large crystals 104 can be ⁇ 300 — 400 and the bulk resistivity can be ⁇ 10 15 /2 — cm.
  • the anisotropy of the hexagonal boron nitride particles 104 can enable percolation of the phononic crystals 102 in the photopolymer matrix 100 along the particle /w-plane axis at lower concentrations possible than isotropic particles.
  • a person skilled in the art will recognize that the improved percolation can cause a substantial increase in viscosity, which can prevent the achievement of thermal conductivities > 1 in a printable system without the other components and make printing with the resin difficult.
  • high density, aggregated medium crystals 106 can be used in combination with the large crystals 104 to provide Attorney Docket No.: 3DF-009 PCT
  • the isotropic nature of these aggregates allows for increased loading of high thermal conductivity boron nitride without incurring an increased viscosity penalty.
  • the smaller size of these medium particles 106 can allow the medium particles 106 to interact synergistically with the monocry stalline hexagonal boron nitride platelets by increasing the packing density without necessarily disrupting the packing and connectivity of the existing hexagonal boron nitride platelet network.
  • the medium crystals 106 can be disposed in the spaces between the large crystals 104.
  • the hBN can form an aggregate of platelets and/or flakes that can be more isotropic than the large crystals 104 and, in some embodiments, can be sized to fit between the large crystals 104.
  • the medium crystals 106 it would not be possible to achieve the necessary particle loadings for high thermal conductivity while maintaining printability on most commercially available three-dimensional printers.
  • the small crystals 108 can be used to promote thermal conductivity by increasing the number of potential contact points to enable percolation in conjunction with the hexagonal boron nitride platelets of the large crystals due to their small size.
  • the small crystals 108 can maximize particle fraction and minimize viscosity of the composition by penetrating spaces between the first and second particles.
  • the thermal conductivity improvement from adding large concentrations of hexagonal aluminum nitride (hAlN) can be minimal due, at least in part, to an absence of percolation for these very small particles.
  • the ceramic filler can be combined with one or more photopolymer resins 110 to form the thermally conductive dielectric photopolymer resin of the present embodiments.
  • the photopolymer resin 110 can include a combination of a resin with one or more Attorney Docket No.: 3DF-009 PCT
  • the resin can include a high performance resin (e.g., monomers, oligomers, photoinitators, and so forth) in combination with a lower viscosity monomer.
  • the high performance resin can include Sartomer resins (e.g.
  • the lower viscosity monomer can include acrylate and methacrylate monomers (e.g. isobomyl acrylate, Methyl 2-((allyloxy)methyl)acrylate, isobomyl methacrylate, etc... ), styrene monomers, and/or N-Vinylpyrrolidone monomers, among others.
  • a viscosity of the lower viscosity monomer can be approximately in a range from about 0.5 cP to about 500 cP, or approximately in a range from about 10 cP to about 200 cP.
  • a dye or pigment for photoadsorption can be added to the high performance resin and/or the lower viscosity monomer to prepare the thermally conductive dielectric photopolymer resin, as discussed in greater detail below.
  • FIG. 2 illustrates this impact of the particle sizes on viscosity in greater detail.
  • FIG. 2 is a graph of viscosity versus volume fraction for ceramic fillers having only large crystals 104 (curve A), large crystals 104 and medium crystals 106 (curve B), and large crystals 104, medium crystals 106, and small crystals 108 (curve C).
  • viscosity of the fillers having only large crystals 104 is significantly higher than the viscosity of the filler having large crystals 104 and medium crystals 106 (curve B), which is higher still than the viscosity of the filler having large crystals 104, medium crystals 106, and small crystals 108 (curve C).
  • a viscosity of the ceramic filled resin can be approximately in a range of about 800 cP to about 250,000 cP, or approximately in a range of about 1000 cP to about 250,000 cP, or approximately in a range of about 3000 cP to about 150,000 cP, or approximately in a range of about 5,000 cP to about 100,000 cP.
  • a viscosity of the ceramic filled resins can be in a range of about 5000 cP to about 100,000 cP for superior thermal conductivity of the thermally conductive dielectric photopolymer resin.
  • resins having a viscosity less than about 5000 cP may not be thermally Attorney Docket No.: 3DF-009 PCT
  • a total volume fraction of the ceramic filler of the present embodiments can be approximately in a range of about 20 vol% to about 60 vol%, or approximately in a range of about 25 vol% to about 50 vol%. It will be appreciated that the total volume fraction can be determined based on the ceramic filler including one or more of large crystals 104 and small crystals 108, medium crystals 106 and small crystals 108, and/or large crystals 104, medium crystals 106, and small crystals 108.
  • the volume fraction of the large crystals 104 in the filler can be approximately in a range of about 10 vol% to about 20 vol%.
  • the volume fraction of the medium crystals 106 in the filler can be approximately in a range of about 5 vol% to about 15 vol%.
  • the volume fraction of the small crystals 108 in the filler can be approximately in a range of about 5 vol% to about 10 vol%.
  • the relative ranges of one or more of these volume fractions can be varied to change a viscosity and/or thermal conductivity of the ceramic filler and/or the resultant thermally conductive dielectric photopolymer resin.
  • the particles can be further modified to maximize percolation while reducing viscosity.
  • the particles can be modified (physically and/or chemically) to improve photokinetic performance for the process of vat photopolymerization.
  • Certain phononic crystals 102 like hexagonal boron nitride or alumina nitride, scatter light and appear bright white, which can lead to scatter issues during vat photopolymerization.
  • one or more of the large-sized particles 104, mediumsized particles 106, small sized particles 108, and/or the photopolymer resin particles 110 can be physically and/or chemically labelled with UV adsorbing material.
  • the physical adsorption of iron oxide nanoparticles onto the boron nitride particles a process discussed in U.S. Patent No. 8,889,761, which is incorporated by reference herein in its entirety, enables iron oxide nanoparticles to act as both UV absorbers and light scatterers.
  • This added functionality can facilitate improved printed part resolution, for instance by mitigating undesired lateral scatter while still allowing sufficient depth of cure.
  • the small-sized particles 108 e.g., the 800 nm hAlN in the embodiment shown in FIG. 1) can provide minimal impediment to the printability of the parts and magnetization is not required.
  • Certain modifications to the particles can offer further functionality including, for example, magnetic alignment capabilities.
  • iron oxide labeled hBN particles can be magnetically aligned during the vat photopolymerization process to offer the possibility for voxel-by-voxel control of thermal conductivity anisotropy to create predefined thermal pathways through a three-dimensionally printed part.
  • a thermal conductivity of the thermally conductive dielectric photopolymer resin can be approximately in a range of about 1 W/m*K to about 10 W/m*K.
  • FIGS. 3A and 3B illustrate one exemplary embodiment of a FLUX ONE 3D printer 10.
  • the printer 10 includes an outer casing or housing 20 in which various components of the printer 10 are disposed.
  • the FLUX ONE 3D printer is designed to use a bottom-up printing technique, and thus includes a build plate 30 that can be advanced vertically, substantially parallel to a longitudinal axis L of the printer 10 such that the build plate 30 can be moved vertically away from a print reservoir 50 in which resin to be cured to form a desired part is disposed.
  • the build plate 30 can be advanced up and down with respect to a linear rail 32 as desired, the linear rail 32 being substantially colinear with the longitudinal axis L.
  • the rail 32 can be considered a vertical rail.
  • the build plate 30 can be associated with the linear rail 32 by way of one or more coupling components, such Attorney Docket No.: 3DF-009 PCT
  • the resin is cured to the build plate 30 and/or to already cured resin to form the printed part in a layer-by-layer manner as the build plate 30 advances away from the reservoir 50.
  • the resin is cured, for example, by a light source and/or a radiation source, as shown a digital light projector 60.
  • the reservoir 50 can include a glass base 52 to allow the digital light projector 60 to pass light into the reservoir 50 to cure the resin.
  • the glass base 52 can more generally be a transparent platform through which light and/or radiation can pass to selective cure the resin.
  • Resin can be introduced to the printer 10 by way of a materials dock 54 that can be accessible, for example via a drawer 22, formed as part of the housing 20.
  • the orientation of the build plate 30, the photopolymer matrix 100 of the thermally conductive dielectric photopolymer resin of the present embodiments, and the glass base 52 during printing are shown in more detail in FIG. 4, with the glass base 52 being shown as a transparent membrane. In other embodiments, a transparent membrane can be provided in addition to a glass or other base 52.
  • One or more mixers can be included to help keep the resin viscous and homogeneous. More particularly, at least one mixer, as shown an external mixer 80, can be in fluid communication with the print reservoir 50 to allow resin to flow out of the reservoir 50, into the mixer 80 to be mixed, and then flow back into the reservoir 50 after it has been mixed by the mixer 80.
  • the mixer 80 can be accessible, for example, via a front panel door 24 provided as part of the housing 20.
  • At least one heating element 82 can be included for use in conjunction with the mixer 80 such that the treated (i.e., mixed) resin is also heated.
  • the heating element 82 is disposed proximate to the print reservoir 50, heating the resin after it has been mixed by the mixer 80, although other location are possible, including but not limited to being incorporated with the mixer 80 to heat and mix simultaneously and/or consecutively.
  • the resin can be heated more than once by additional heating elements as well.
  • Resin that travels from the reservoir 50, to the mixer 80, and back to the reservoir 50 can flow through any number of conduits or tubes configured to allow resin to travel therethrough, such as the conduits 84 illustrated in FIG. 3B.
  • the resin can also flow through a reservoir manifold 56, which can be disposed above the print reservoir 50.
  • the manifold 56 can serve a variety of purposes, including but Attorney Docket No.: 3DF-009 PCT
  • the manifold can be designed to allow resin to be mixed and/or heated to flow out of the reservoir 50, as well as allow mixed and/or heated resin to flow into the reservoir 50 via ports formed therein.
  • Electrical connections to help operate various features associated with the reservoir 50 can be passed through the manifold 56.
  • the electrical connections may be associated with various electronics and the like housed within the printer 10, for example in an electronics panel 90. Additional details about a reservoir manifold are provided for in International Patent Application No. WO 2021/217102, entitled “Manifold and Related Methods for Use with a Reservoir for Additive Manufacturing,” the contents of which is incorporated by reference herein in its entirety.
  • a magnetic fiber alignment system 92 can be provided for as part of the printer 10. Such a system 92 can help to control aspects of a print job when magnetic functional additives, such as magnetic particles, are associated with the resin being printed. More specifically, the system 92 can include one or more magnets and/or magnetic field generators that enable the location of the magnetic particle including resin to be controlled by the system 92. Other functional additives that are not necessarily magnetic can also be incorporated with the resin.
  • a touch screen 26 or other user interface can be included as part of the housing 20 to allow a user to input various parameters for a print job and/or for instructions, signals, warnings, or other information to be passed along by any systems of the printer 10 to a user.
  • the housing 20 can include an openable and/or removable hood 28 that enables a printed part, as well as components of the printer 10, to be accessed.
  • the hood 28 can also include a viewing portion, such as a window 29, that allows a user to view a print job being performed. As shown, the build plate 30, and thus a part being printed that will be attached to the build plate 30, can be seen through the window 29. Further, the reservoir 50, manifold 56, and other components of the printer 10 can also be visible through the window 29.
  • FIG. 5 illustrates one embodiment of a method 200 of manufacturing the TCDR of the present embodiments.
  • the ceramic filler can include a combination of large crystals 104, medium crystals 106, and small crystals 108.
  • the large crystals 104 can be magnetized through physioisorption of superparamagnetic iron oxide nanoparticles (SPIONs) (S202).
  • SPIONs superparamagnetic iron oxide nanoparticles
  • a photopolymer resin that can include a high performance resin having monomers, oligomers, and/or photoinitiators, etc., in combination with a lower viscosity monomer, can be mixed with the ceramic filler (S206). Once sufficiently mixed, the mixture can form the TCDR (S208).
  • a method 300 of manufacturing the TCDR can be performed without magnetization through physioisorption of superparamagnetic iron oxide nanoparticles (SPIONs). Rather, a dye or pigment 112 for photoadsorption can be combined with the high performance resin having monomers, oligomers, and/or photoinitiators, as well as the lower viscosity monomer.
  • the ceramic filler which can be in powdered form and dried (S304), can be mixed with the photopolymer resin (S306). Once sufficiently mixed, the mixture can form the TCDR (S308).
  • the ceramic filler can include a combination of large crystals 104 and small crystals 108.
  • the large crystals 104 can be magnetized through physioisorption of superparamagnetic iron oxide nanoparticles (SPIONs) (S402).
  • SPIONs superparamagnetic iron oxide nanoparticles
  • the ceramic filler which can be in powdered form, can be dried (S404).
  • a photopolymer resin that can include the high performance resin having monomers, oligomers, and/or photoinitiators, etc., in combination with a lower viscosity monomer, can be mixed with the ceramic filler (S406). Once sufficiently mixed, the mixture can form the TCDR (S408).
  • FIG. 8 A graphically ?TI* ?TI* illustrates a comparison of the resin of the present embodiments 100 to other materials, e.g., competitive photoresins and/or stainless steel that are typically utilized for thermal conductivity applications.
  • thermal conductivity of the TCDR is superior to conventional photoresins, with conventional photoresins for vat polymerization having poor Attorney Docket No.: 3DF-009 PCT
  • the TCDR can include an electrical resistivity that is equal to, or greater, than conventional photoresins.
  • the electrical resistivity can have significantly higher values than copper and stainless steel.
  • the electrical resistivity of the TCDR of the present embodiments can be in approximately a range of about 10 12 ohm-cm to about IO 20 ohm-cm.
  • the TCDR of the present embodiments can be used to print a heat exchanger 130, as shown in FIG. 8B.
  • the heat exchanger 130 can be used for heat conduction applications that can be on par, or even superior to, conventional heat exchangers machined from metal-filled parts.
  • the heat exchanger 130 can include one or more macrochannels 132 formed therein for flowing a working fluid therethrough.
  • the macrochannels 132 can be nestled al ong-side one another with substantially no gaps between adjacent macrochannels 132.
  • Each macrochannel can have a working fluid flowing therethrough.
  • the working fluid flowing through the macrochannels 102 can be in a gas or liquid form.
  • critical carbon dioxide can run through the macrochannels, the critical carbon dioxide being more like a liquid but runs like a gas.
  • a high surface area and thermal conductivity of the heat exchanger 130 can increase the heat transfer coefficient.
  • these microporous features can be engineered to be highly anisotropic — long microscale channels in the flow direction — which can significantly decrease the pressure loss along the heat exchanger 130.
  • the core can provide additional structural rigidity to the macrochannels 132, thereby allowing operation at high fluid pressures.
  • FIG. 8C The superior thermal conductivity that results from producing an objecting using the TCDR of the present disclosure is illustrated by FIG. 8C, which compares heat conduction of the heat exchanger 130 with the heat conduction of a three-dimensionally printed heat exchanger with conventional material 230 in an infrared image that compares these heat exchangers side-by-side.
  • the heat exchanger 130 When imaged with a Forward Looking Infrared (FLIR) camera shortly after turning a heating source on the heat exchanger 130 and the three-dimensionally printed heat exchanger with conventional material 230, the heat exchanger 130 shows faster movement of heat and associated temperature rise through the material while the three- Attorney Docket No.: 3DF-009 PCT
  • FLIR Forward Looking Infrared
  • Thermal conductivity values of the resin 100 of the present embodiments being approximately in the range of about 1 - ⁇ -to about 10 can allow three-dimensionally TTi*K TTi*K printed heat exchangers to be printed to include bespoke geometries, high resolution, 3D printing only geometries, custom manufacturing, fast prototyping, and so forth.
  • particle loadings and/or ratios of monocry stalline hexagonal boron nitride can be changed with respect to the high density boron nitride agglomerates. Leveraging additional shear and vibration during printing can also enable higher particle loadings and thermal conductivities.
  • inorganic dyes can be used instead of a magnetization process to control light scattering. While particle alignment can be lost in such embodiments, a higher volume fraction of isotropic silicon carbide of different sizes can be loaded while utilizing photo-sensitizers to improve depth of cure. It will be appreciated that thermoplastic polymers can achieve the same performance using similar particles with extrusion based additive manufacturing.
  • heat exchangers e.g, those with and without internal channels, such as a tube heat exchanger 260
  • other objects that can be printed with TCDR that would benefit from the properties that result from the present disclosures.
  • These other objects include, but are not limited to: a heat sink 360, a cold plate 460, a cold plate with internal cooling channels, a thermal spreader, a thermally conductive encapsulant, or an electrical connector, e.g., such as for electric vehicle (EV) charging ports 500, including but not limited to an adapter 502 and/or a plug 504 of the same, and/or battery terminal encapsulants 600, among others.
  • EV electric vehicle
  • the TCDR can include tribological properties such as wear resistance or low friction, as well as interesting RF properties.
  • tribological properties such as wear resistance or low friction
  • many of the phononic ceramics including hBN, graphene, and M0S2 can exhibit planar structures bound together by van der Waals interactions. These structures can be cleaved under low energy, which can make these materials common candidates for dry lubricants.
  • TCDR can include about >20 vol% phononic ceramic and can exhibit dry lubrication properties in its final printed state. Moreover, to the touch, TCDR can feel low-friction. Such material properties make TCDR a good candidate for applications that use low friction.
  • a composition for additive manufacturing comprising: a photopolymer resin; and a ceramic particle filler that includes at least two of the following: a first set of anisotropic particles in a non-agglomerated state, a particle size of the major axis of the first set of anisotropic particle being approximately in a range of about 20 pm to about 75 pm; an aggregate of particles having a particle size of the major axis of the aggregate of particles being approximately in a range of about 15 pm to about 30 pm; and a third set of anisotropic particles in a non-agglomerated state, a particle size of the major axis of the third set of anisotropic particles being approximately in a range of about 150 nm to about 8000 nm.
  • composition of example 1 wherein a total volume fraction of the ceramic filler is approximately in a range of about 20 vol% to about 60 vol%.
  • composition of example 1 or example 2, wherein the first set of anisotropic particles comprises monocry stalline boron nitride platelets in approximately a range of about 10 vol% to about 20 vol%.
  • composition of any of examples 1 to 3, wherein the aggregate of particles comprises boron nitride aggregates in approximately a range of about 5 vol% to about 15 vol%.
  • composition of any of examples 1 to 4, wherein the third set of anisotropic particles comprises aluminum nitride platelets in approximately a range of about 5 vol% to about 10 vol%.
  • composition of any of examples 1 to 7, wherein the viscosity of the composition is approximately in a range of about 1000 cP to about 250,000 cP.
  • composition of any of examples 1 to 8, wherein a thermal conductivity of the composition is approximately in a range of about 1 W/m*K to about 10 W/m*K.
  • a thermally conductive dielectric resin composition comprising: a mixture of flakes that includes: a first set of flakes in a non-agglomerated state; a second agglomerate of flakes; and a third set of flakes in a non-agglomerated state; and a photopolymer resin; wherein a size of the major axis of the first set of flakes is larger than a size of the major axis of the second agglomerate of flakes, and the size of the major axis of the second agglomerate of flakes is larger than a size of the major axis of the third set of flakes, and wherein a thermal conductivity of the thermally conductive dielectric photopolymer resin is approximately in a range of about 1 W/m*K to about 10 W/m*K.
  • composition of example 10, wherein a viscosity of the thermally conductive dielectric photopolymer resin is approximately in a range of about 1,000 cP to about 250,000 cP.
  • thermoly conductive dielectric photopolymer resin has a dielectric strength approximately in a range of about 20 kV/mm to about 40 kV/mm.
  • thermoly conductive dielectric photopolymer resin has an electrical resistivity approximately in the range of about 10 12 ohm-cm to about IO 20 ohm-cm.
  • composition of any of examples 10 to 14, wherein the second agglomerate of flakes comprises flakes that are more isotropic than the first set of flakes, the size of the major axis of the second agglomerate of flakes being approximately in a range of about 15 pm to about 30 pm.
  • composition of any of examples 10 to 16, wherein the second agglomerate of flakes comprises hBN aggregates and AIN aggregates.
  • a method of producing an object having high thermal conductivity and low electrical conductivity by additive manufacturing comprising: depositing a photopolymer resin having a thermal conductivity approximately in a range of about 1 W/m*K to about 10 W/m*K to form a layer of a three-dimensional object; and depositing the photopolymer resin to form one or more additional layers of the three- dimensional object, wherein an electrical resistivity of the three-dimensional object is approximately in a range of about 10 12 ohm-cm to about IO 20 ohm-cm.
  • the photopolymer resin comprises: a first set of anisotropic particles in a non-agglomerated state, a particle size of the major axis of the first set of anisotropic particles being approximately in a range of about 35 pm to about 60 pm; a second set of particles in an agglomerated state, the second set of particle being more isotropic than the first set of anisotropic particles, a particle size of the major axis of the second set of particles being approximately in a range of about 15 pm to about 30 pm; and a third set of anisotropic particles in a non-agglomerated state, a particle size of the major axis of the third set of anisotropic particles being approximately in a range of about 150 nm to about 8000 nm.
  • a method of forming a polymer matrix composite for use in additive manufacturing comprising: combining at least two of: a first set of flakes in a non-agglomerated state; a second agglomerate of flakes, or a third set of flakes in a non-agglomerated state; drying the combination of the at least two of the first set of flakes, the second agglomerate of flakes, or the third set of flakes; and combining the dried combination with a high-performance resin and a lower viscosity monomer to form a thermally conductive dielectric resin, wherein, when the first set of flakes is present, they are anisotropic, when the third set of flakes is present, they are anisotropic, and when the second agglomerate of flakes is present, they are more isotropic than at least one of the first set of flakes or the third set of flakes.
  • a method of forming a polymer matrix composite for use in additive manufacturing comprising: magnetizing a first set of flakes in a non-agglomerated state; combining the magnetized first set of flakes with a second set of flakes in a nonagglomerated state; drying the combination of first and second sets of flakes; and combining the dried combination with a high-performance resin and a lower viscosity monomer to form a thermally conductive dielectric resin, wherein the first and third sets of flakes are anisotropic.
  • magnetizing a first set of flakes in a nonagglomerated state comprises using physisorption of superparamagnetic iron oxide nanoparticles in conjunction with the same.

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Abstract

L'invention concerne des formulations de matériau diélectrique thermoconducteur et leurs procédés de fabrication. Dans certains modes de réalisation, la résine photopolymère diélectrique thermoconductrice peut comprendre une résine photopolymère combinée à une charge céramique. La charge céramique peut comprendre des cristaux phononiques comportant de grands, moyens et petits cristaux pour obtenir une charge de particules élevée de telle sorte qu'une thermoconductivité élevée et une facilité d'utilisation de la résine pendant l'impression soient maintenues. Dans certains modes de réalisation, la résine photopolymère diélectrique thermoconductrice peut incorporer des charges de différentes tailles de particules et différents états de dispersion pour réduire la viscosité de la résine photopolymère diélectrique thermoconductrice à une valeur appropriée pour une impression.
PCT/US2022/040671 2021-08-17 2022-08-17 Formulations de photopolymère diélectrique thermoconducteur compatibles avec la fabrication additive par polymérisation en cuve WO2023023207A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20170136699A1 (en) * 2014-06-06 2017-05-18 Northeastern University Additive Manufacturing of Discontinuous Fiber Composites Using Magnetic Fields
WO2018226709A1 (fr) * 2017-06-05 2018-12-13 3D Fortify Systèmes et procédés d'alignement de particules anisotropes pour la fabrication additive
US20190047047A1 (en) * 2016-12-02 2019-02-14 Markforged, Inc. 3d printing internal free space
US20190386251A1 (en) * 2016-10-28 2019-12-19 3M Innovative Properties Company Nanostructured article

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20170136699A1 (en) * 2014-06-06 2017-05-18 Northeastern University Additive Manufacturing of Discontinuous Fiber Composites Using Magnetic Fields
US20190386251A1 (en) * 2016-10-28 2019-12-19 3M Innovative Properties Company Nanostructured article
US20190047047A1 (en) * 2016-12-02 2019-02-14 Markforged, Inc. 3d printing internal free space
WO2018226709A1 (fr) * 2017-06-05 2018-12-13 3D Fortify Systèmes et procédés d'alignement de particules anisotropes pour la fabrication additive

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