KR-102963183-B1 - MELT EMULSION EXTRUSION METHODS FOR PRODUCING THERMOPLASTIC POLYMER PARTICLES

KR102963183B1KR 102963183 B1KR102963183 B1KR 102963183B1KR-102963183-B1

Abstract

A method for manufacturing thermoplastic polymer particles may include the steps of: mixing a mixture comprising a thermoplastic polymer and a carrier fluid immiscible with the thermoplastic polymer in an extruder at a temperature higher than the melting point or softening temperature of the thermoplastic polymer and at a shear rate sufficiently high to disperse the thermoplastic polymer in the carrier fluid; cooling the mixture to a temperature below the melting point or softening temperature of the thermoplastic polymer to form solidified particles comprising thermoplastic polymer particles having a circularity of 0.90 or higher and containing the thermoplastic polymer; and separating the solidified particles from the carrier fluid.

Inventors

발레리에 엠. 페루지아
마이클 에스. 호킨스
데이비드 존 윌리엄 로톤
캐롤린 패트리시아 무어레그

Assignees

제록스 코포레이션

Dates

Publication Date: 20260513
Application Date: 20200831
Priority Date: 20200630

Claims (20)

A step of providing a mixture comprising an emulsion stabilizer, a thermoplastic polymer, and a carrier fluid immiscible with respect to the thermoplastic polymer at a temperature higher than the melting point or softening temperature of the thermoplastic polymer; A step of shearing the mixture into molten thermoplastic polymer droplets in an extruder at a temperature higher than the melting point or softening temperature of the thermoplastic polymer and at a shear rate sufficiently high to disperse the thermoplastic polymer in the carrier fluid, thereby forming an emulsion having an emulsion stabilizer between the thermoplastic polymer and the carrier fluid, wherein the emulsion stabilizer comprises nanoparticles having a D50 of 1 nm to 500 nm, and the nanoparticles comprise a plurality of metal oxide nanoparticles, carbon black, or any combination thereof; A step of cooling the emulsion in the presence of the nanoparticles to a temperature below the melting point or softening temperature of the thermoplastic polymer to form solidified particles, wherein the solidified particles have a circularity of 0.90 or higher and contain the thermoplastic polymer, and the nanoparticles form a coating on the outer surface of the solidified particles; and A method comprising the step of separating the solidified particles from the carrier fluid; A method in which the step of cooling the emulsion to form solidified particles occurs within the extruder and/or after the emulsion exits the extruder.
In claim 1, A method in which at least some of the above nanoparticles are embedded within the outer surface of the above solidified particles.
In claim 1, A method in which at least some of the solidified particles have pores, and the pores have the nanoparticles at the pore/thermoplastic polymer interface.
In claim 3, A method in which the above nanoparticles are embedded within the above void/thermoplastic polymer interface.
In claim 3, The above void is a method for accommodating the carrier fluid.
In claim 1, The above nanoparticles include silica nanoparticles.
In claim 1, A method in which the solidified particles further comprise long structures on the outer surface of the solidified particles, and the long structures comprise the thermoplastic polymer.
In claim 1, A method in which the emulsion stabilizer is present in the mixture in an amount of 0.01% to 10% by weight based on the weight of the thermoplastic polymer.
In claim 1, A method in which the thermoplastic polymer is present in the mixture in an amount of 5% to 60% by weight of the mixture.
In claim 1, The above thermoplastic polymer is a copolymer comprising polyamide, polyurethane, polyethylene, polypropylene, polyacetal, polycarbonate, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polytrimethylene terephthalate (PTT), polyhexamethylene terephthalate, polystyrene, polyvinyl chloride, polytetrafluoroethene, polyester, polylactic acid, polyether, polyether sulfone, polyether ether ketone, polyacrylate, polymethacrylate, polyimide, acrylonitrile butadiene styrene (ABS), polyphenylene sulfide, vinyl polymer, polyarylene ether, polyarylene sulfide, polysulfone, polyether ketone, polyamide-imide, polyetherimide, polyether ester, polyether block, and polyamide block (PEBA or polyether block amide), grafted or non-grafted thermoplastic polyolefin, functionalized or non-functionalized ethylene/vinyl monomer polymer, functionalized or non-functionalized ethylene/alkyl (meth)acrylate, functionalized or non-functionalized (meth)acrylic acid polymer, functionalized or non-functionalized ethylene/vinyl monomer/alkyl (meth)acrylate terpolymer, ethylene/vinyl monomer/carbonyl terpolymer, ethylene/alkyl (meth)acrylate/carbonyl terpolymer, methyl methacrylate-butadiene-styrene (MBS)-type core-shell polymer, polystyrene-block-polybutadiene-block-poly(methyl methacrylate) (SBM) block terpolymer, chlorinated or chlorosulfonated polyethylene, polyvinylidene fluoride (PVDF), phenolic resin, poly(ethylene/vinyl acetate), polybutadiene, A method selected from the group consisting of polyisoprene, styrene-based block copolymer, polyacrylonitrile, silicone, and any combination thereof.
In claim 1, A method in which the melting point or softening temperature of the above thermoplastic polymer is 50°C to 450°C.
In claim 1, A method in which a temperature higher than the melting point or softening temperature of the thermoplastic polymer is 1°C to 50°C higher than the melting point or softening temperature of the thermoplastic polymer.
In claim 1, The above carrier fluid is selected from the group consisting of silicone oil, fluorinated silicone oil, perfluorinated silicone oil, polyethylene glycol, alkyl-terminated polyethylene glycol, paraffin, liquid petroleum jelly, mink oil, turtle oil, soybean oil, perhydrosqualene, sweet almond oil, calophyllum oil, palm oil, parleam oil, grapeseed oil, sesame oil, maize oil, rapeseed oil, sunflower oil, cottonseed oil, apricot oil, castor oil, avocado oil, jojoba oil, olive oil, grain germ oil, esters of lanoleic acid, esters of oleic acid, esters of lauric acid, esters of stearic acid, fatty esters, higher fatty acids, fatty alcohols, polysiloxanes modified with fatty acids, polysiloxanes modified with fatty alcohols, polysiloxanes modified with polyoxyalkylenes, and any combination thereof.
In claim 1, A method in which cooling is performed at a rate of 10℃/hour to 100℃/second.
In claim 1, The above extruder is selected from the group consisting of a single-screw extruder, a twin-screw extruder, and an extruder comprising two or more co-rotating or reverse-rotating screws.
In claim 1, The above extruder has two or more zones of different temperatures.
In claim 1, The above-mentioned solidified particles are a method in which D10 is 0.5 μm to 125 μm, D50 is 1 μm to 200 μm, D90 is 70 μm to 300 μm, and D10 < D50 < D90.
In claim 1, The above-mentioned solidified particles are a method having a diameter span of 0.2 to 10.
A step of producing a mixture by feeding an emulsion stabilizer containing nanoparticles having a D50 of 1 nm to 500 nm, a thermoplastic polymer, and a carrier fluid into an extruder in any order; A step of shearing the mixture in an extruder at a temperature 1 to 50°C higher than the melting point or softening temperature of the thermoplastic polymer and at a sufficiently high shear rate to form an emulsion comprising molten thermoplastic polymer droplets dispersed in the carrier fluid, wherein the emulsion stabilizer is located at the interface between the molten thermoplastic polymer droplets and the carrier fluid; A step of forming solidified particles by cooling the emulsion in the presence of the nanoparticles at a rate of 10°C/hour to 100°C/second to a temperature below the melting point or softening temperature of the thermoplastic polymer, wherein the solidified particles have a circularity of 0.90 or higher and contain the thermoplastic polymer, and the nanoparticles form a coating on the outer surface of the solidified particles; and A method comprising the step of separating the solidified particles from the carrier fluid; The carrier fluid is immiscible with the thermoplastic polymer at a temperature higher than the melting point or softening temperature of the thermoplastic polymer, and the emulsion stabilizer is not an internal additive of the thermoplastic polymer, The above nanoparticles comprise a plurality of metal oxide nanoparticles, carbon black, or any combination thereof, and A method in which the step of cooling the emulsion to form solidified particles occurs within the extruder and/or after the emulsion exits the extruder.
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Description

Melt Emulsion Extrusion Methods for Producing Thermoplastic Polymer Particles The present invention relates to thermoplastic polymer particles and a method for manufacturing such particles. Such particles, particularly highly spherical thermoplastic polymer particles, may be particularly useful as source materials for additive manufacturing. Three-dimensional (3-D) printing, also known as additive manufacturing, is a rapidly growing field of technology. While 3-D printing has traditionally been used for rapid prototyping tasks, this technology is increasingly being used to produce commercial and industrial objects that can have structural and mechanical tolerances completely different from those of rapid prototypes. 3-D printing operates by depositing (a) small droplets or streams of molten or solidifiable material or (b) fine powder particles at precise deposition sites for subsequent consolidation into larger objects that may have multiple complex geometries. Such deposition and consolidation processes typically occur under computer control to provide a layer-by-layer buildup of larger objects. In certain examples, the consolidation of fine powder particles may occur in 3-D printing systems that use a laser to facilitate selective laser sintering (SLS). Incomplete interlayer fusion can result in structural weaknesses that can be problematic for printing objects with demanding structural and mechanical tolerances. Powder particles usable for 3-D printing include thermoplastic polymers, including thermoplastic elastomers, metals, and other solidifiable materials. Although a wide range of thermoplastic polymers are known, relatively few possess properties suitable for 3-D printing, particularly when using Powder Bed Fusion (PBF). Additive manufacturing methods using powder materials include PBF, Selective Laser Sintering (SLS), Selective Heat Sintering (SHS), Selective Laser Melting (SLM), Electron Beam Melting (EBM), Binder Jetting, and Multi-Jet Fusion (MJF). In the SLS printing method, particles are fused together by energy from a high-power laser. Typical thermoplastic polymers suitable for 3-D printing include those having distinct melting and recrystallization points approximately 20 to 50°C lower than their melting points. These differences allow for more effective coalescence between adjacent polymer layers, which can promote improved structural and mechanical integrity. To achieve good printing performance using powder microparticles, particularly polymer powder microparticles, the powder microparticles must maintain good flow characteristics in the solid state. Flow characteristics can be evaluated, for example, by measuring the fraction of powder microparticles from a sample that can pass through a standard sieve of a specific size and/or by measuring the angle of repose. A high fraction of sievable powder microparticles may indicate that the particles exist as substantially individual, non-aggregated particles, which can be a characteristic of ready powder flow. Additionally, a low value of the angle of repose can be a characteristic of ready powder flow. A relatively narrow particle size distribution and regularity of the particle geometry within the sample can also help promote good powder flow performance. Commercially available powder microparticles are often obtained by cryogenic grinding or sedimentation processes, which can result in irregular particle shapes and a wide particle size distribution. Irregular particle shapes can lead to poor powder flow performance during the 3-D printing process. Furthermore, powder microparticles with irregular shapes, particularly those obtained from current commercial processes, can provide poor packing efficiency after deposition and compaction; consequently, extensive voids may form within the printed object because the powder microparticles are not tightly packed together during deposition. In this regard, a wide particle size distribution can similarly be a problem. Poor powder flow performance can be addressed to some extent through dry blending with fillers and flow aids, but this technique may have limited effectiveness for softer polymeric materials, such as elastomers, due to particle aggregation. The present invention relates to thermoplastic polymer particles and a melt emulsion extrusion method for producing such particles. Such particles, particularly highly spherical thermoplastic polymer particles, can be particularly useful as source materials for additive manufacturing. A method is described herein comprising the steps of: mixing a mixture comprising a thermoplastic polymer and a carrier fluid immiscible with the thermoplastic polymer in an extruder at a temperature higher than the melting point or softening temperature of the thermoplastic polymer and at a shear rate sufficiently high to disperse the thermoplastic polymer in the carrier fluid; cooling the mixture to a temperature lower than the melting point or softening temperature of