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US-12617950-B2 - Polymer particles comprising lignin and related additive manufacturing methods

US12617950B2US 12617950 B2US12617950 B2US 12617950B2US-12617950-B2

Abstract

Thermoplastic polymer particles suitable for use in additive manufacturing and related methods may comprise lignin. For example, said polymer particles may comprise a thermoplastic polymer, a lignin, optionally an emulsion stabilizer, and optionally a compatibilizer. Said polymer particles may be produced by melt emulsification methods and be highly spherical and, consequently, suited for selective laser sintering methods of additive manufacturing.

Inventors

  • Valerie M. Farrugia
  • Shivanthi Easwari Sriskandha

Assignees

  • XEROX CORPORATION

Dates

Publication Date
20260505
Application Date
20211027

Claims (14)

  1. 1 . A composition comprising: polymer particles comprising a thermoplastic polymer, a lignin, an emulsion stabilizer comprising nanoparticles, and optionally a compatibilizer; wherein the nanoparticles are embedded in at least a portion of an outer surface of the polymer particles during a melt emulsification process forming the polymer particles, and the nanoparticles comprise metal oxide nanoparticles, carbon black, or any combination thereof; and wherein the polymer particles have an aerated density of about 0.5 g/cm 3 to about 0.8 g/cm 3 .
  2. 2 . The composition of claim 1 , wherein the polymer particles have a circularity of about 0.90 to about 1.0.
  3. 3 . The composition of claim 1 , wherein the lignin comprises a modified lignin.
  4. 4 . The composition of claim 3 , wherein the modified lignin comprises lignin molecules grafted with the thermoplastic polymer.
  5. 5 . The composition of claim 1 , wherein the lignin comprises a modified lignin and an unmodified lignin.
  6. 6 . The composition of claim 1 , wherein the lignin is present in the polymer particles in an amount of about 1 wt % to about 90 wt % of the thermoplastic polymer.
  7. 7 . The composition of claim 1 , wherein the polymer particles have an angle of repose of about 25° to about 45°.
  8. 8 . The composition of claim 1 , wherein the polymer particles have a Hausner ratio of about 1.0 to about 1.5.
  9. 9 . The composition of claim 1 , wherein the polymer particles have a D10 of about 0.1 μm to about 125 μm, a D50 of about 0.5 μm to about 200 μm, and a D90 of about 3 μm to about 300 μm, wherein D10<D50<D90.
  10. 10 . The composition of claim 1 , wherein the polymer particles have a diameter span of about 0.2 to about 10.
  11. 11 . The composition of claim 1 , wherein the polymer particles have a tapped density of about 0.6 g/cm 3 to about 0.9 g/cm 3 .
  12. 12 . The composition of claim 1 , wherein the polymer particles have a BET surface area of about 10 m 2 /g to about 500 m 2 /g.
  13. 13 . The composition of claim 1 , wherein the nanoparticles comprise silica nanoparticles.
  14. 14 . A method comprising: shearing a mixture comprising: a thermoplastic polymer, a lignin, a carrier fluid, and an emulsion stabilizer comprising nanoparticles at a temperature at or greater than a melting point or softening temperature of the thermoplastic polymer to emulsify a thermoplastic polymer melt in the carrier fluid; cooling the mixture to below the melting point or softening temperature to form polymer particles; and separating the polymer particles from the carrier fluid, wherein the polymer particles comprise the thermoplastic polymer, the lignin, and the emulsion stabilizer; wherein the nanoparticles are embedded in at least a portion of an outer surface of the polymer particles, and the nanoparticles comprise metal oxide nanoparticles, carbon black, or any combination thereof; and wherein the polymer particles have an aerated density of about 0.5 g/cm 3 to about 0.8 g/cm 3 .

Description

FIELD OF INVENTION The present disclosure relates to polymer particles suitable for use in additive manufacturing and related methods. BACKGROUND Lignin is a renewable feedstock and is also the second most abundant biopolymer on earth. This polyphenolic fiber provides plants with their rigidity. The worldwide generation of lignin is beyond 100 million dry tons/year as a by-product of pulp and paper-making. The price of lignin ranges from 200 to 500 USD/dry ton. Compared to polyethylene which is well over 1000 USD/dry ton, lignin is inexpensive and vastly available. Researchers from both academia and industry are testing the feasibility of incorporating lignin with conventional polymers, such as nylon or polyamides to create composite materials, mainly for fused filament fabrication (FFF) methods of three-dimensional (3-D) printing, also known as additive manufacturing. However, FFF methods generally require a material (e.g., a polymeric material) that can be easily extruded and has excellent weld strength between layers along with outstanding mechanical properties. However, lignin can only be heated to about 200° C. before lignin starts to decompose, while the softening temperature of lignin is around 100° C. Further, if the temperature of the lignin becomes too high or lignin is exposed to heat for too long, the lignin viscosity will increase beyond the ability to properly flow. Therefore, there is a narrow operating window with temperature and processing time limitations for implementing lignin in additive manufacturing. Selective laser sintering (SLS) is a type of known as additive manufacturing that produces plastic parts by using a laser to sinter consecutive layers of polymeric powder. Because of operating limitations of lignin for blending with other polymers, research in SLS powders has been limited to admixture of lignin particles and particles of other polymers like nylon. While objects have been successfully printed, the composition of the objects includes portions of lignin fused to portions of the other polymer, which, in effect, may introduce grain boundaries. Therefore, the mechanical properties of the object may be more dependent on how well the lignin particles fuse to the other polymer particles to a greater extent than the mechanical properties of the lignin and other polymer. SUMMARY OF INVENTION The present disclosure relates to polymer particles that comprise a thermoplastic polymer and lignin and that are suitable for use in additive manufacturing and related methods where warping in additive manufacturing methods like SLS may be mitigated. Disclosed herein are methods that comprise: mixing a mixture comprising: a thermoplastic polymer, a lignin, a carrier fluid, and optionally an emulsion stabilizer at a temperature at or greater than a melting point or softening temperature of the thermoplastic polymer to emulsify a thermoplastic polymer melt in the carrier fluid; cooling the mixture to below the melting point or softening temperature to form polymer particles; and separating the polymer particles from the carrier fluid, wherein the polymer particles comprise the thermoplastic polymer, the lignin, the emulsion stabilizer, if included. Further disclosed herein are compositions that comprise: polymer particles comprising a thermoplastic polymer, a lignin, optionally an emulsion stabilizer, and optionally a compatibilizer. Disclosed herein are methods that comprise: depositing first polymer particles and optionally second polymer particles different than the first particles onto a surface, wherein the first polymer particles comprising a thermoplastic polymer, a lignin, optionally an emulsion stabilizer, and optionally a compatibilizer; and once deposited, exposing at least a portion of the first and second particles, when included, to a laser to fuse the first and second particles, when included, and form a consolidated body. Further disclosed herein are selective laser sintered articles comprising polymer particles sintered together, wherein the polymer particles comprise first polymer particles comprising a thermoplastic polymer, a lignin, optionally an emulsion stabilizer, and optionally a compatibilizer. BRIEF DESCRIPTION OF THE DRAWINGS The following figures are included to illustrate certain aspects of the disclosure, and should not be viewed as exclusive configurations. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, as will occur to those skilled in the art and having the benefit of this disclosure. FIG. 1 is a flow chart of a nonlimiting example method 100 of the present disclosure. FIGS. 2-3 are scanning electron micrographs of control polymer particles described in the examples. FIGS. 4-6 are scanning electron micrographs of polymer particles described in the examples and according to at least some embodiments of the present disclosure. DETAILED DESCRIPTION The present disclosure relates