Highly thermally conductive ultrahigh molecular weight polyethylene composition, method of making and use thereof

Abstract

The application discloses a kind of high thermal conductivity ultra-high molecular weight polyethylene composition preparation method and application, belong to high molecular polymer technical field.Its technical scheme includes following weight parts of component: ultra-high molecular weight polyethylene 100 parts, graphene ethanol suspension of adsorbing ionic liquid 5-20 parts, carbon nanotube 0.5-20 parts, coupling agent 0.01-3 parts, dispersing agent 0.01-5 parts, inorganic thermal conductive filler 0.5-20 parts, antioxidant 0.1-0.5 parts.The composition prepared by the application has uniform particle size distribution, suitable particle size, and is suitable for selective laser sintering processing;Inorganic filler forms three-dimensional thermal conduction path, has higher thermal conductivity, selective laser sintering processing preheating temperature is relatively low, reduces the thermal shrinkage of three-dimensional product, and the molded product prepared using the composition has smooth surface, good thermal conductivity and flexible adjustable structure.

Description

Technical Field

[0001] This invention belongs to the field of polymer technology, specifically relating to a high thermal conductivity ultra-high molecular weight polyethylene composition, its preparation method, and its application. Background Technology

[0002] Ultra-high molecular weight polyethylene (UHMWPE), as an engineering plastic, possesses unparalleled advantages over other plastics due to its high molecular weight, numerous banded molecules, and abundant molecular entanglement. These advantages include high strength, high abrasion resistance, high impact resistance, excellent chemical corrosion resistance, and excellent low-temperature resistance. Furthermore, UHMWPE also boasts low density, excellent hygienic properties, water resistance, self-lubrication, and resistance to scaling. The main limitation to UHMWPE's application is its processing; pipe processing efficiency is slow, with traditional extrusion processes only producing 2-10 meters of pipe per day.

[0003] Selective Laser Sintering (SLS), a mainstream 3D printing technology, was first invented and patented by the University of Texas in the mid-1980s and later commercialized by DTM Corporation. SLS primarily uses powder materials as raw materials and a laser as the heat source, employing a layer-by-layer stacking principle to directly create three-dimensional solids from CAD drawings. SLS's advantages lie in its wide selection of raw materials, including various powders such as polymers, ceramics, and sand, and the relatively simple post-processing of the finished product. Patent CN105172154A proposes a selective laser sintering method for ultra-high molecular weight polyethylene (UHMWPE). UHMWPE powder is heated to a preheating temperature in a selective laser sintering molding device. Using a predetermined laser scanning speed and output power, the resulting UHMWPE powder is shaped in the selective laser sintering device to obtain a molded part. The molded part is then removed, held at a certain temperature, and cooled to obtain the UHMWPE molded component.

[0004] Ultra-high molecular weight polyethylene (UHMWPE) has a high viscosity due to its high molecular weight, which is not conducive to powder spreading in selective laser sintering (SLS) processes. In addition, defects such as the particle shape and particle size distribution uniformity and poor heat resistance of UHMWPE compositions also limit its use as a raw material for laser sintering processes: if the powder particle size is too large, the surface of the three-dimensional product is rough; if the particle size is too fine, the adhesion is serious, and powder spreading cannot be achieved during the sintering process.

[0005] Patent CN107686577A discloses an ultra-high molecular weight polyethylene (UHMWPE) composition and its applications, as well as a laser sintering method and three-dimensional products. The polyethylene composition described in this patent contains granular UHMWPE and granular inorganic fillers. The UHMWPE has a viscosity-average molecular weight of 1.5-5 million and a particle size of 20-200 μm; the inorganic filler has a particle size of 2.6-25 μm. The three-dimensional products prepared by selective laser sintering of the polyethylene composition provided by this invention have a smooth surface, are hard, and have strong wear resistance. However, the three-dimensional products prepared by selective laser sintering of this UHMWPE composition cannot be used in some applications requiring high thermal conductivity, such as capillary radiator arrays, and the preheating temperature is relatively high; the shrinkage rate of the three-dimensional products is not clearly defined.

[0006] Therefore, it is necessary to design a high thermal conductivity ultra-high molecular weight polyethylene polymer suitable for selective laser sintering and to use it to prepare high thermal conductivity three-dimensional products. Summary of the Invention

[0007] This invention provides a high thermal conductivity ultra-high molecular weight polyethylene composition, its preparation method, and its applications. The prepared composition has a uniform particle size distribution and suitable particle size for selective laser sintering (SLS). The inorganic filler forms a three-dimensional thermally conductive pathway and has high thermal conductivity. The SLS preheating temperature is relatively low, reducing the thermal shrinkage rate of the three-dimensional product. Molded products prepared using this composition have smooth surfaces, good thermal conductivity, and flexible and adjustable structures, making them suitable for applications requiring high thermal conductivity.

[0008] The technical solution of this invention is as follows:

[0009] In a first aspect, a high thermal conductivity ultra-high molecular weight polyethylene composition is disclosed, comprising the following components in parts by weight:

[0010]

[0011]

[0012] Preferably, the viscosity-average molecular weight of the ultra-high molecular weight polyethylene is 2 million to 8 million, more preferably 3 million to 6 million, and even more preferably 4 million to 5 million; the mesh size of the ultra-high molecular weight polyethylene powder is 60 to 140 mesh, preferably 80% to 140 mesh or more, and even more preferably 100% to 140 mesh or more; the particle size d50 is 110 to 165 μm, preferably 115 to 135 μm.

[0013] Preferably, the preparation method of the graphene-ethanol suspension adsorbed with ionic liquid is as follows: graphene and ionic liquid are placed in a quartz vessel, ground for 15-30 minutes, and then poured into a glass vessel. Anhydrous ethanol is added based on a graphene-to-anhydrous ethanol mass ratio of 0.1-1, and the mixture is sonicated for 30-60 minutes to obtain the graphene-ethanol suspension adsorbed with ionic liquid. The ionic liquid is one or more of quaternary ammonium salt ionic liquids, quaternary phosphonium salt ionic liquids, imidazole salt ionic liquids, pyrrole salt ionic liquids, halogen ionic liquids, tetrafluoroborate ionic liquids, and hexafluorophosphate ionic liquids, preferably one or more of 1-hexyl-3-methylimidazolium chloride, 1-dodecyl-3-methylimidazolium tetrafluoroborate, 1-butyl-1-methylpyrrolidine bis(trifluoromethanesulfonyl)imino salt, 1-butyl-3-methylimidazolium hexafluorophosphate, and methyltrioctylammonium chloride. The mass ratio of graphene to ionic liquid is 0.5-2:1.

[0014] Preferably, the carbon nanotubes are one or more of single-walled carbon nanotubes and multi-walled carbon nanotubes, with a tube length of 5-100 μm, preferably 40-70 μm; and a tube diameter of 0.5-40 nm, preferably 1-20 nm.

[0015] Preferably, the coupling agent is one or more of titanate coupling agents and silane coupling agents, and more preferably, one or more of γ-aminopropyltriethoxysilane coupling agent, γ-(2,3-epoxypropoxy)propyltrimethoxysilane coupling agent, γ-methacryloyloxypropyltrimethoxysilane, isopropyl dioleoyloxy(dioctylphosphoyloxy)titanate, and isopropyl tri(dioctylphosphoyloxy)titanate.

[0016] Preferably, the dispersant is one or more of calcium stearate, zinc stearate, tin stearate, vinyl bis-stearamide, and polyethylene wax.

[0017] Preferably, the inorganic thermally conductive filler is one or more of magnesium oxide, aluminum oxide, silicon carbide, boron nitride, aluminum nitride, magnesium carbonate, and magnesium hydroxide, and the particle size of the inorganic filler is 500-5000 mesh, preferably 1000-3000 mesh.

[0018] Preferably, the antioxidant is one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (1010), octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (1076), and tris[2,4-di-tert-butylphenyl]phosphite (168).

[0019] Secondly, a method for preparing the aforementioned high thermal conductivity ultra-high molecular weight polyethylene composition is provided, specifically as follows:

[0020] Ultra-high molecular weight polyethylene powder, graphene-ethanol suspension with adsorbed ionic liquid, carbon nanotubes, inorganic thermally conductive filler, dispersant, antioxidant, and coupling agent are mixed using a high-speed pulverizer at a speed of 2000-5000 rpm for 2-4 minutes to avoid overheating of the pulverizer motor due to excessively long pulverization time. Pulverization is performed in two stages, each lasting 1-2 minutes, with a 5-minute pause after the first stage before starting the second stage. The mixture after the second pulverization is sieved using a 1000-5000 mesh sieve, preferably a 1000-3000 mesh sieve, to produce a high thermal conductivity ultra-high molecular weight polyethylene composition.

[0021] Thirdly, regarding the application of the high thermal conductivity ultra-high molecular weight polyethylene composition, a three-dimensional product is obtained using the composition prepared by the method described in claim 9, as follows:

[0022] 1) The structural model of the molded part is designed using 3D software and uploaded to the control host;

[0023] 2) Spread the powder composition material evenly on the selective laser sintering worktable, and heat the worktable to the preheating temperature of 125-130℃;

[0024] 3) The ultra-high molecular weight polyethylene powder composition is formed layer by layer in a selective laser sintering molding equipment by using a predetermined sintering thickness, laser scanning speed and output power to obtain a molded part;

[0025] 4) To reduce warping and deformation during use, the three-dimensional products need to be heat-annealed to eliminate internal stress. The three-dimensional products are subjected to a pressure of 2-4 times their own weight; the programmed annealing holding temperature is set in a programmable temperature-controlled forced-air oven: heating rate of 1℃ / min from room temperature to 80-90℃, holding for 1-2 hours; heating rate of 2℃ / min from 80-90℃ to 110-128℃, holding for 4-6 hours; cooling rate of 2℃ / min from 110-128℃ to 70-80℃, holding for 3-4 hours; cooling rate of 1℃ / min back to room temperature, and the ultra-high molecular weight polyethylene three-dimensional products are obtained.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. This invention provides a high thermal conductivity ultra-high molecular weight polyethylene composition that can be processed using laser sintering. Graphene, carbon nanotubes, and inorganic thermally conductive fillers adsorbing ionic liquids can form a three-dimensional thermally conductive pathway. Two-dimensional graphene materials with high specific surface area can be connected by one-dimensional carbon nanotubes with high aspect ratios to form a heat transfer pathway. Furthermore, the thermally conductive filler is filled between the graphene and carbon nanotubes to further connect the heat transfer pathways. The resulting composition exhibits excellent thermal conductivity, with the high thermal conductivity ultra-high molecular weight polyethylene composition reaching a thermal conductivity of up to 18 W / mK, significantly higher than that of traditional plastic materials.

[0028] 2. The presence of small amounts of graphene and carbon nanotubes lowers the crystallization and melting temperatures of the high thermal conductivity ultra-high molecular weight polyethylene (UHMWPE) composition (see Appendix Table 8). To ensure the molding of 3D products, the preheating temperature is generally selected near the melting point; the holding temperature is generally set at the temperature corresponding to the low crystallization rate, allowing the 3D product to crystallize slowly, releasing internal stress gradually and eliminating internal defects. The reduction in the crystallization and melting temperatures of the high thermal conductivity UHMWPE composition can reduce the preheating temperature, annealing holding temperature, and holding time for laser sintering printing. Simultaneously, applying a load and using programmed temperature control during annealing can reduce the warpage deformation of the 3D product (thermal shrinkage test results are shown in Appendix Table 9).

[0029] 3. This high thermal conductivity ultra-high molecular weight polyethylene composition can be processed by selective laser sintering. The inorganic filler forms a three-dimensional thermal conduction path and has high thermal conductivity. The presence of the inorganic filler reduces the preheating temperature of the three-dimensional product and the thermal shrinkage rate of the three-dimensional product. The molded product has a smooth surface, good thermal conductivity, and flexible and adjustable structure. Detailed Implementation

[0030] Example 1

[0031] (1) Preparation of ultra-high molecular weight polyethylene composition

[0032] The preparation method of graphene ethanol suspension adsorbed with ionic liquid is as follows: 0.5g of graphene and 1g of 1-hexyl-3-methylimidazolium chloride are placed in a quartz grinding dish and manually ground for 15min. Then, 5g of anhydrous ethanol is added and the mixture is sonicated for 30min to obtain graphene ethanol suspension adsorbed with ionic liquid.

[0033] 100g of ultra-high molecular weight polyethylene powder (viscosity-average molecular weight 3 million g / mol, particle size d50 165um, 80-140 mesh accounting for 93.5%, particle size distribution results are shown in Table 1 below), 6.5g of graphene ethanol suspension with adsorbed ionic liquid, 3g of single-walled carbon nanotubes (tube length 95um, tube diameter 40nm), 0.5g of γ-aminopropyltriethoxysilane coupling agent (KH-550), 0.5g of calcium stearate, 5g of alumina (1000 mesh), and 0.2g of tris(2,4-di-tert-butylphenyl) phosphite (antioxidant 168) were mixed in a high-speed pulverizer at 3000 rpm for 2 minutes per pulverization. To avoid overheating of the pulverizer motor due to excessively long pulverization time, the pulverizer was stopped for 5 minutes after the first pulverization before a second pulverization was started for 1 minute. A high thermal conductivity ultra-high molecular weight polyethylene composition A1 was prepared by sieving the mixture after secondary crushing through a 2500-mesh sieve. The thermal conductivity of the ultra-high molecular weight polyethylene composition was measured to be 12.1 W / mK.

[0034] Table 1

[0035]

[0036]

[0037] (2) Preparation of three-dimensional products using selective laser sintering

[0038] Selective laser sintering (SLS) was performed using a LaserCore-5300 rapid prototyping machine manufactured by Beijing Longyuan Automatic Molding System Co., Ltd., based on ultra-high molecular weight polyethylene (UHMWPE) composition A1 as raw material. At the start of the molding process, the molding cylinder worktable was lowered by one layer thickness, and a thick layer of powder was laid. This powder was preheated to a temperature slightly below its melting point. Under computer control, the laser beam selectively sintered the powder material according to the contour information of the model in the computer. After one layer was completed, a planar layer was obtained. The worktable was then lowered by one layer height, another layer of powder was laid, and the sintering process was repeated until a three-dimensional product was obtained. Process parameters: preheating temperature 128℃, laser power output ratio 70%, scanning speed 1m / s, sintered layer thickness 0.15mm.

[0039] The three-dimensional product is subjected to a pressure four times its own weight; in a programmable temperature-controlled forced-air oven, the programmable annealing and holding temperatures are set as follows: the heating rate is 1℃ / min to raise the temperature from room temperature to 85℃ and hold for 2 hours, the heating rate is 2℃ / min to raise the temperature from 90℃ to 125℃ and hold for 5 hours, the cooling rate is 2℃ / min to lower the temperature to 75℃ and hold for 3 hours, and the temperature is lowered to room temperature at 1℃ / min, and the ultra-high molecular weight polyethylene three-dimensional product is obtained by cooling.

[0040] Example 2

[0041] (1) Preparation of ultra-high molecular weight polyethylene composition

[0042] The preparation method of graphene ethanol suspension adsorbing ionic liquid is as follows: 1.5g of graphene and 1.5g of 1-dodecyl-3-methylimidazolium tetrafluoroborate are placed in a quartz grinding dish and manually ground for 18min. 6g of anhydrous ethanol is added and the mixture is sonicated for 45min to obtain graphene ethanol suspension adsorbing ionic liquid.

[0043] 100g of ultra-high molecular weight polyethylene powder (viscosity-average molecular weight 4 million g / mol, particle size d50) The following components were mixed: 150µm (100-140 mesh) accounting for 87.5% (particle size distribution results are shown in Table 2 below); 9g of graphene-ethanol suspension containing adsorbed ionic liquid; 5g of single-walled carbon nanotubes (80µm in length and 30nm in diameter); 1.5g of γ-(2,3-epoxypropoxy)propyltrimethoxysilane coupling agent (KH560); 0.8g of polyethylene wax; 8g of magnesium hydroxide (1500 mesh); and 0.2g of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] (antioxidant 1010). The mixture was prepared by a high-speed pulverizer at 3000 rpm for 2 minutes per pulverization. To avoid overheating of the pulverizer motor due to excessive pulverization time, the pulverizer was stopped for 5 minutes after the first pulverization before a second pulverization was started for 1 minute. The mixture after the second pulverization was sieved through a 1500-mesh sieve to produce a high thermal conductivity ultra-high molecular weight polyethylene composition A2. The thermal conductivity of the ultra-high molecular weight polyethylene composition A2 was measured to be 13.6 W / mK.

[0044] Table 2

[0045] Sieving rate percentage,% ≥40 mesh 0.1 60 mesh 4.2 80 mesh 8.1 100 mesh 75.3 120 mesh 8.7 140 mesh 3.5 ≤160 mesh 0.1

[0046] (2) Preparation of three-dimensional products using selective laser sintering

[0047] Selective laser sintering was performed using ultra-high molecular weight polyethylene composition A2 as raw material. At the start of the molding process, the molding cylinder stage was lowered by one layer thickness, and a thick layer of powder was laid. This powder was preheated to a temperature slightly below its melting point. Under computer control, the laser beam selectively sintered the powder material based on the contour information of the model in the computer. After one layer was completed, a flat layer was obtained. The stage was then lowered by one layer height, another layer of powder was laid, and the sintering process was repeated until a thermally conductive three-dimensional product with a smooth surface was obtained. Process parameters: Preheating temperature: 126℃, laser power output ratio: 60%, scanning speed: 1.5m / s, sintered layer thickness: 0.2mm.

[0048] The three-dimensional product is subjected to a pressure three times its own weight; in a programmable temperature-controlled forced-air oven, the programmable annealing and holding temperatures are set as follows: the temperature is increased from room temperature to 80℃ at a rate of 1℃ / min and held for 2 hours, then increased to 120℃ at a rate of 2℃ / min and held for 6 hours, then decreased to 70℃ at a rate of 2℃ / min and held for 4 hours, and finally decreased to room temperature at a rate of 1℃ / min, and the ultra-high molecular weight polyethylene three-dimensional product is obtained after cooling.

[0049] Example 3

[0050] (1) Preparation of ultra-high molecular weight polyethylene composition

[0051] The preparation method of graphene ethanol suspension for adsorbing ionic liquid is as follows: Take 2g of graphene and 3g of 1-butyl-1-methylpyrrolidine bis(trifluoromethanesulfonyl)imino salt in a quartz grinding dish, grind manually for 25min, add 8g of anhydrous ethanol, and sonicate for 60min to obtain graphene ethanol suspension for adsorbing ionic liquid.

[0052] 100g of ultra-high molecular weight polyethylene powder (viscosity-average molecular weight 5 million g / mol, particle size d50) The following materials were used: 13g of graphene-ethanol suspension containing 135µm of ionic liquid (86.7% of which were 100-140 mesh, particle size distribution shown in Table 3); 6g of single-walled carbon nanotubes (60µm long, 10nm diameter); 2g of γ-methacryloyloxypropyltrimethoxysilane (KH570); 1g of vinyl bis-stearamide; 10g of silicon carbide; and 0.2g of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076). These were mixed using a high-speed pulverizer at 3000 rpm for 2 minutes per pulverization. To prevent overheating of the pulverizer motor due to prolonged pulverization, the pulverizer was stopped for 5 minutes after the first pulverization before a second pulverization for 1 minute. The mixture after the second pulverization was sieved through a 1500-mesh sieve to prepare a high thermal conductivity ultra-high molecular weight polyethylene composition A3. The thermal conductivity of ultra-high molecular weight polyethylene composition A3 was measured to be 15.8 W / mK.

[0053] Table 3

[0054] Sieving rate percentage,% ≥40 mesh 0 60 mesh 2.8 80 mesh 10.4 100 mesh 44.8 120 mesh 37.8 140 mesh 4.1 ≤160 mesh 0.1

[0055] (2) Preparation of three-dimensional products using selective laser sintering

[0056] Selective laser sintering was performed using ultra-high molecular weight polyethylene composition A3 as raw material. At the start of the molding process, the molding cylinder stage was lowered by one layer thickness, and a thick layer of powder was laid. This powder was preheated to a temperature slightly below its melting point. Under computer control, the laser beam selectively sintered the powder material based on the contour information of the model in the computer. After one layer was completed, a flat layer was obtained. The stage was then lowered by one layer height, another layer of powder was laid, and the sintering process was repeated until a thermally conductive three-dimensional product with a smooth surface was obtained. Process parameters: Preheating temperature: 123℃, laser power output ratio: 50%, scanning speed: 2m / s, sintered layer thickness: 0.25mm.

[0057] The three-dimensional product is subjected to a pressure twice its own weight; in a programmable temperature-controlled forced-air oven, the programmable annealing and holding temperatures are set as follows: the heating rate is 1℃ / min to raise the temperature from room temperature to 75℃ and hold for 2 hours, the heating rate is 2℃ / min to raise the temperature to 115℃ and hold for 5 hours, the cooling rate is 2℃ / min to lower the temperature to 70℃ and hold for 3 hours, and the temperature is lowered to room temperature at 1℃ / min, and the ultra-high molecular weight polyethylene three-dimensional product is obtained by cooling.

[0058] Example 4

[0059] (1) Preparation of ultra-high molecular weight polyethylene composition

[0060] The preparation method of graphene ethanol suspension for adsorbing ionic liquid is as follows: Take 4g of graphene and 4g of 1-butyl-3-methylimidazolium hexafluorophosphate in a quartz grinding dish, grind manually for 25min, add 8g of anhydrous ethanol, and sonicate for 60min to obtain graphene ethanol suspension for adsorbing ionic liquid.

[0061] 100g of ultra-high molecular weight polyethylene powder (viscosity-average molecular weight 5 million g / mol, 100-140 mesh content 87.6%, particle size distribution results are shown in Table 4 below, particle size d50) The following components were mixed: 16g of graphene-ethanol suspension containing adsorbed ionic liquid (120µm), 3g of single-walled carbon nanotubes (60µm long, 10nm diameter), 3g of multi-walled carbon nanotubes (80µm long, 30nm diameter), 2g of isopropyl dioleoyloxy (dioctylphosphoyloxy) titanate (GR101), 1.5g of zinc stearate, 12g of boron nitride (2500 mesh), and 0.3g of tris(2,4-di-tert-butylphenyl) phosphite (antioxidant 168). The mixture was prepared using a high-speed pulverizer at 3000 rpm for 2 minutes per pulverization. To prevent overheating of the pulverizer motor due to prolonged pulverization, the pulverizer was stopped for 5 minutes after the first pulverization before a second pulverization, lasting 1 minute. The mixture after the second pulverization was sieved through a 2000-mesh sieve to produce a high thermal conductivity ultra-high molecular weight polyethylene composition A4. The thermal conductivity of the ultra-high molecular weight polyethylene composition was measured to be 18.2 W / mK.

[0062] Table 4

[0063] Sieving rate percentage,% ≥40 mesh 0 60 mesh 4.5 80 mesh 7.9 100 mesh 31.7 120 mesh 49.3 140 mesh 6.6 ≤160 mesh 0

[0064] (2) Preparation of three-dimensional products using selective laser sintering

[0065] Selective laser sintering was performed using ultra-high molecular weight polyethylene (UHMWPE) composition A4 as raw material. At the start of the molding process, the molding cylinder stage was lowered by one layer thickness, and a thick layer of powder was laid. This powder was preheated to a temperature slightly below its melting point. Under computer control, the laser beam selectively sintered the powder material based on the contour information of the model in the computer. After one layer was completed, a flat layer was obtained. The stage was then lowered by one layer height, another layer of powder was laid, and the sintering process was repeated until a thermally conductive three-dimensional product with a smooth surface was obtained. Process parameters: Preheating temperature: 125℃, laser power output ratio: 60%, scanning speed: 1.5m / s, sintered layer thickness: 0.15mm.

[0066] The three-dimensional product is subjected to a pressure three times its own weight; in a programmable temperature-controlled forced-air oven, the programmable annealing and holding temperatures are set as follows: the heating rate is 1℃ / min to raise the temperature from room temperature to 82℃ and hold for 2 hours, the heating rate is 2℃ / min to raise the temperature to 122℃ and hold for 4 hours, the cooling rate is 2℃ / min to lower the temperature to 72℃ and hold for 4 hours, and the temperature is lowered to room temperature at 1℃ / min, and the ultra-high molecular weight polyethylene three-dimensional product is obtained by cooling.

[0067] Example 5

[0068] (1) Preparation of ultra-high molecular weight polyethylene composition

[0069] The preparation method of graphene ethanol suspension for adsorbing ionic liquid is as follows: Take 5g of graphene and 5g of methyltrioctylammonium chloride and place them in a quartz grinding dish. Grind manually for 25min, add 8g of anhydrous ethanol, and sonicate for 60min to obtain graphene ethanol suspension for adsorbing ionic liquid.

[0070] 100g of ultra-high molecular weight polyethylene powder (viscosity-average molecular weight 5 million g / mol, 80.9% of particles are 100-140 mesh, particle size distribution is shown in Table 5 below, particle size d50 125um), 18g of graphene ethanol suspension with adsorbed ionic liquid, 4g of single-walled carbon nanotubes (80um in length, 40nm in diameter), 2g of multi-walled carbon nanotubes (100um in length, 40nm in diameter), 1.5g of isopropyl tris(dioctylphosphoyloxy)titanate (GR102), 1g of tin stearate, 14g of aluminum nitride (3000 mesh), 0.2g of tris(2,4-di-tert-butylphenyl) phosphite (antioxidant 168), β-( 0.1 g of octadecyl 3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076) was mixed using a high-speed grinder at 3000 rpm for 2 minutes per grinding cycle. To prevent overheating of the grinder motor due to excessive grinding time, the grinder was stopped for 5 minutes after the first grinding cycle before a second grinding cycle of 1 minute. The mixture after the second grinding cycle was sieved through a 3000-mesh sieve to produce a high thermal conductivity ultra-high molecular weight polyethylene composition A5. The thermal conductivity of the ultra-high molecular weight polyethylene composition was measured to be 16.5 W / mK.

[0071] Table 5

[0072] Sieving rate percentage,% ≥40 mesh 0 60 mesh 8.3 80 mesh 10.8 100 mesh 22.3 120 mesh 35.9 140 mesh 22.7 ≤160 mesh 0

[0073] (2) Preparation of three-dimensional products using selective laser sintering

[0074] Selective laser sintering was performed using ultra-high molecular weight polyethylene (UHMWPE) composition A5 as raw material. At the start of the molding process, the molding cylinder stage was lowered by one layer thickness, and a thick layer of powder was laid. This powder was preheated to a temperature slightly below its melting point. Under computer control, the laser beam selectively sintered the powder material based on the contour information of the model in the computer. After one layer was completed, a flat layer was obtained. The stage was then lowered by one layer height, another layer of powder was laid, and the sintering process was repeated until a thermally conductive three-dimensional product with a smooth surface was obtained. Process parameters: Preheating temperature: 127℃, laser power output ratio: 70%, scanning speed: 1m / s, sintered layer thickness: 0.1mm.

[0075] The three-dimensional product is subjected to a pressure three times its own weight; in a programmable temperature-controlled forced-air oven, the programmable annealing and holding temperatures are set as follows: the heating rate is 1℃ / min to raise the temperature from room temperature to 85℃ and hold for 2 hours, the heating rate is 2℃ / min to raise the temperature to 124℃ and hold for 4 hours, the cooling rate is 2℃ / min to lower the temperature to 75℃ and hold for 4 hours, and the temperature is lowered to room temperature at 1℃ / min, and the ultra-high molecular weight polyethylene three-dimensional product is obtained by cooling.

[0076] Comparative Example 1

[0077] (1) Preparation of ultra-high molecular weight polyethylene composition

[0078] Comparative composition B1 was prepared according to the ultra-high molecular weight polyethylene composition of Example 1. The difference between composition B1 and Example 1 is that the ultra-high molecular weight polyethylene powder in the raw materials for preparation of composition B1 has a molecular weight of 9 million. Otherwise, it is the same as Example 1.

[0079] (2) Preparation of three-dimensional products using selective laser sintering

[0080] Selective laser sintering of B1 was performed according to the method in Example 1. Despite multiple process explorations, smooth three-dimensional products could not be prepared. This was because the high molecular weight of ultra-high molecular weight polyethylene resulted in poor flowability and adhesion after preheating, making the products difficult to mold.

[0081] Comparative Example 2

[0082] (1) Preparation of ultra-high molecular weight polyethylene composition

[0083] Comparative composition B2 was prepared according to the ultra-high molecular weight polyethylene composition of Example 1. The difference between composition B2 and Example 1 is that the proportion of ultra-high molecular weight polyethylene powder with a particle size of 80-140 mesh is not controlled in the raw materials for the preparation of composition B2. The specific particle size is shown in Table 6.

[0084] Table 6

[0085] Sieving rate percentage,% ≥40 mesh 25.8 60 mesh 20.3 80 mesh 17.3 100 mesh 12.6 120 mesh 14.9 140 mesh 3.5 ≤160 mesh 5.6

[0086] (2) Preparation of three-dimensional products using selective laser sintering

[0087] Selective laser sintering of B2 was performed according to the method in Example 1. Despite multiple process explorations, a complete three-dimensional product could not be obtained. This was mainly due to the coarse particle size and uneven particle size distribution of ultra-high molecular weight polyethylene, uneven preheating and melting of the powder, excessively high temperature causing small-sized particles to stick together and making powder spreading difficult, and excessively low temperature resulting in incomplete melting of large-sized particles.

[0088] Comparative Example 3

[0089] (1) Preparation of ultra-high molecular weight polyethylene composition

[0090] Comparative composition B3 was prepared according to the ultra-high molecular weight polyethylene composition of Example 1. The difference is that the proportion of ultra-high molecular weight polyethylene powder with a particle size of 80-140 mesh was not controlled in the raw materials for preparing composition B3, as shown in Table 7.

[0091] Table 7

[0092] Sieving rate percentage,% ≥40 mesh 0.3 60 mesh 8.7 80 mesh 15.9 100 mesh 13.2 120 mesh 10.8 140 mesh 13.2 ≤160 mesh 38.2

[0093] (2) Preparation of three-dimensional products using selective laser sintering

[0094] Selective laser sintering of B3 was performed according to the method in Example 1. Despite multiple process explorations, a complete three-dimensional product could not be obtained, mainly due to the excessively fine particle size of ultra-high molecular weight polyethylene, resulting in severe adhesion and difficulty in powder spreading during sintering.

[0095] Comparative Example 4

[0096] (1) Preparation of ultra-high molecular weight polyethylene composition

[0097] Comparative composition B4 was prepared according to the ultra-high molecular weight polyethylene composition of Example 1, except that the thermally conductive filler in the raw materials for preparing composition B4 has a mesh size of 6500.

[0098] (2) Preparation of three-dimensional products using selective laser sintering

[0099] Selective laser sintering was performed on B4 according to the method in Example 1. Despite multiple process explorations, a complete three-dimensional product could not be obtained; the thermally conductive filler was too fine and exhibited severe agglomeration.

[0100] Comparative Example 5

[0101] (1) Preparation of ultra-high molecular weight polyethylene composition

[0102] Comparative composition B5 was prepared according to the ultra-high molecular weight polyethylene composition of Example 1, except that graphene-ethanol suspension containing adsorbed ionic liquid was not added to the raw materials for the preparation of composition B5. The thermal conductivity of composition B5 was measured to be 3.5 W / mK.

[0103] (2) Preparation of three-dimensional products using selective laser sintering

[0104] Selective laser sintering of B5 according to the method in Example 1 failed to yield a complete three-dimensional product. Further investigation confirmed the following process conditions for selective laser sintering: preheating temperature 132℃, laser power output ratio 70%, scanning speed 1m / s, and sintered layer thickness 0.15mm; after molding, the three-dimensional product was subjected to a pressure four times its own weight; in a programmable temperature-controlled oven, the following programmed annealing and holding temperatures were set: heating rate of 1℃ / min from room temperature to 88℃, holding for 2 hours; heating rate of 2℃ / min from 88℃ to 130℃, holding for 5 hours; cooling rate of 2℃ / min to 80℃, holding for 3 hours; cooling rate of 1℃ / min to room temperature, yielding a three-dimensional ultra-high molecular weight polyethylene product. The preheating and holding temperatures were significantly higher than in the previous example.

[0105] Comparative Example 6

[0106] (1) Preparation of ultra-high molecular weight polyethylene composition

[0107] Comparative composition B6 was prepared according to the ultra-high molecular weight polyethylene composition of Example 1, except that carbon nanotubes were not added to the raw materials for the preparation of composition B6. The thermal conductivity of composition B6 was measured to be 2.5 W / mK.

[0108] (2) Preparation of three-dimensional products using selective laser sintering

[0109] Selective laser sintering of B5 according to the method in Example 1 failed to yield a complete three-dimensional product. Further investigation confirmed the following process conditions for selective laser sintering: preheating temperature 134℃, laser power output ratio 70%, scanning speed 1m / s, and sintered layer thickness 0.15mm; after molding, the three-dimensional product was subjected to a pressure four times its own weight; in a programmable temperature-controlled oven, the following programmed annealing and holding temperatures were set: heating rate of 1℃ / min from room temperature to 90℃, holding for 2 hours; heating rate of 2℃ / min from 90℃ to 130℃, holding for 5 hours; cooling rate of 2℃ / min to 80℃, holding for 3 hours; cooling rate of 1℃ / min to room temperature, yielding a three-dimensional ultra-high molecular weight polyethylene product. The preheating and holding temperatures were significantly higher than in the previous example.

[0110] Comparative Example 7

[0111] (1) Preparation of ultra-high molecular weight polyethylene composition

[0112] Comparative composition A1 was prepared according to the ultra-high molecular weight polyethylene composition of Example 1.

[0113] (2) Preparation of three-dimensional products using selective laser sintering

[0114] Selective laser sintering was performed using ultra-high molecular weight polyethylene composition A1 as raw material. At the start of the molding process, the molding cylinder stage was lowered by one layer thickness, and a thick layer of powder was laid. This powder was preheated to a temperature slightly below its melting point. Under computer control, the laser beam selectively sintered the powder material based on the contour information of the model in the computer. After one layer was completed, a planar layer was obtained. The stage was then lowered by one layer height, another layer of powder was laid, and the sintering process was repeated until a three-dimensional product was obtained. Process parameters: preheating temperature 128℃, laser power output ratio 70%, scanning speed 1m / s, sintered layer thickness 0.15mm.

[0115] The three-dimensional product is subjected to no load pressure; it is annealed in a blower oven with unprogrammable temperature control at a holding temperature of 125℃ for 10 hours, and then cooled to obtain the ultra-high molecular weight polyethylene three-dimensional product.

[0116] The crystallization temperature and melting temperature of the polyethylene compositions prepared in Examples 1-5 and Comparative Example 5 are shown in Table 8. As can be seen from Table 1, the presence of a small amount of graphene and carbon nanotubes reduced the crystallization temperature and melting temperature of the high thermal conductivity ultra-high molecular weight polyethylene compositions.

[0117] Table 8

[0118]

[0119] Shrinkage and surface roughness of the three-dimensional products of Examples 1-5 and Comparative Examples 5-6 were measured, as shown in Table 9.

[0120] Table 9

[0121] serial number Shrinkage rate, % Surface roughness, MPa Example 1 1.5 34 Example 2 1.1 34 Example 3 0.8 33 Example 4 1 35 Example 5 1.3 36 Comparative Example 5 1.8 38 Comparative Example 6 3 34

[0122] As shown in Table 9, compared with Comparative Examples 5 and 6, the shrinkage rate of Examples 1-5 is relatively small. This is mainly because the synergistic effect of the graphene and carbon nanotubes adsorbing the ionic liquid lowers the crystallization temperature and melting temperature of the high thermal conductivity ultra-high molecular weight polyethylene composition, thereby lowering the preheating temperature and annealing temperature of laser sintering. This results in the slow release of internal stress and reduces warping deformation caused by stress. Compared with Comparative Example 7, the shrinkage rate of Examples 1-5 is relatively small, mainly because the load pressure and programmed temperature control coordinate to reduce warping deformation during the annealing process of the three-dimensional products.

[0123] Although the present invention has been described in detail by way of preferred embodiments, the invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high thermal conductivity ultra-high molecular weight polyethylene composition, characterized in that, The components include the following parts by weight: 100 parts of ultra-high molecular weight polyethylene 5-20 parts of graphene-ethanol suspension with adsorption of ionic liquid 0.5-20 parts of carbon nanotubes Coupling agent 0.01-3 parts Dispersant 0.01-5 parts Inorganic thermally conductive filler 0.5-20 parts Antioxidant 0.1-0.5 parts; The ultra-high molecular weight polyethylene has a viscosity-average molecular weight of 2 million to 8 million, and the ultra-high molecular weight polyethylene powder has a mesh size of 60 to 140 mesh and a particle size d50 of 110 to 165 μm. The specific preparation method of graphene ethanol suspension adsorbed with ionic liquid is as follows: graphene and ionic liquid are placed in a quartz vessel, ground for 15-30 minutes, and then poured into a glass vessel. Anhydrous ethanol is added based on a graphene to anhydrous ethanol mass ratio of 0.1-1, and the mixture is sonicated for 30-60 minutes to obtain the graphene ethanol suspension adsorbed with ionic liquid. The ionic liquid is one or more of the following: quaternary ammonium salt ionic liquid, quaternary phosphonium salt ionic liquid, imidazole salt ionic liquid, pyrrole salt ionic liquid, halide ionic liquid, tetrafluoroborate ionic liquid, and hexafluorophosphate ionic liquid. The mass ratio of graphene to ionic liquid is 0.5-2:

1. The carbon nanotubes are one or more of single-walled carbon nanotubes and multi-walled carbon nanotubes, with a tube length of 5-100 μm and a tube diameter of 0.5-40 nm.

2. The high thermal conductivity ultra-high molecular weight polyethylene composition as described in claim 1, characterized in that, The ultra-high molecular weight polyethylene has a viscosity-average molecular weight of 3-6 million; the ultra-high molecular weight polyethylene powder has a mesh size of 80-140 mesh, accounting for more than 80%; and the particle size d50 is 115-135 μm.

3. The high thermal conductivity ultra-high molecular weight polyethylene composition as described in claim 2, characterized in that, The ultra-high molecular weight polyethylene has a viscosity-average molecular weight of 4-5 million; the ultra-high molecular weight polyethylene powder has a mesh size of 100-140, accounting for more than 80%.

4. The high thermal conductivity ultra-high molecular weight polyethylene composition as described in claim 1, characterized in that, The ionic liquid is one or more of the following: 1-hexyl-3-methylimidazolium chloride, 1-dodecyl-3-methylimidazolium tetrafluoroborate, 1-butyl-1-methylpyrrolidine bis(trifluoromethanesulfonyl)imino salt, 1-butyl-3-methylimidazolium hexafluorophosphate, and methyltrioctylammonium chloride.

5. The high thermal conductivity ultra-high molecular weight polyethylene composition as described in claim 1, characterized in that, The carbon nanotubes are one or more of single-walled carbon nanotubes and multi-walled carbon nanotubes, with a tube length of 40-70 μm and a tube diameter of 1-20 nm.

6. The high thermal conductivity ultra-high molecular weight polyethylene composition as described in claim 1, characterized in that, The coupling agent is one or more of titanate coupling agents and silane coupling agents.

7. The high thermal conductivity ultra-high molecular weight polyethylene composition as described in claim 6, characterized in that, The coupling agent is one or more of the following: γ-aminopropyltriethoxysilane coupling agent, γ-(2,3-epoxypropoxy)propyltrimethoxysilane coupling agent, γ-methacryloxypropyltrimethoxysilane, isopropyl dioleoyloxy(dioctylphosphoyloxy)titanate, and isopropyl tri(dioctylphosphoyloxy)titanate.

8. The high thermal conductivity ultra-high molecular weight polyethylene composition as described in claim 1, characterized in that, The dispersant is one or more of calcium stearate, zinc stearate, tin stearate, vinyl bis-stearamide, and polyethylene wax.

9. The high thermal conductivity ultra-high molecular weight polyethylene composition according to claim 1, characterized in that, The inorganic thermally conductive filler is one or more of magnesium oxide, aluminum oxide, silicon carbide, boron nitride, aluminum nitride, magnesium carbonate, and magnesium hydroxide, and the particle size of the inorganic filler is 500-5000 mesh.

10. The high thermal conductivity ultra-high molecular weight polyethylene composition as described in claim 9, characterized in that, The particle size of the inorganic filler is 1000-3000 mesh.

11. The high thermal conductivity ultra-high molecular weight polyethylene composition according to claim 1, characterized in that, The antioxidant is one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and tris[2,4-di-tert-butylphenyl]phosphite.

12. A method for preparing the composition according to any one of claims 1-10, characterized in that: Ultra-high molecular weight polyethylene powder, graphene-ethanol suspension with adsorbed ionic liquid, carbon nanotubes, inorganic thermally conductive filler, dispersant, antioxidant, and coupling agent are mixed in a high-speed pulverizer at a speed of 2000-5000 rpm for 2-4 minutes. The pulverization is carried out in two stages, each lasting 1-2 minutes, with a 5-minute pause after the first pulverization before the second pulverization. The mixture after the second pulverization is then sieved through a 1000-5000 mesh sieve to produce a high thermal conductivity ultra-high molecular weight polyethylene composition.

13. The method for preparing the composition according to claim 12, characterized in that: Use a 1000-3000 mesh sieve to sieve the mixture after secondary crushing.

14. A three-dimensional article obtained from the composition prepared by the method of claim 12, characterized in that, The specific method is as follows: 1) The ultra-high molecular weight polyethylene composition powder material prepared by the preparation method according to claim 12 is heated to a preheating temperature of 125-130℃; 2) The ultra-high molecular weight polyethylene composition powder is formed in a selective laser sintering molding equipment using a laser scanning speed of 0.5~2m / s and an output power of 30~70%, with a sintering thickness of 0.15~0.25mm, to obtain a three-dimensional product; 3) The three-dimensional product is subjected to a pressure of 2-4 times its own weight; the programmed annealing and holding temperature is set in the forced-air drying oven: the heating rate is 1℃ / min to raise the temperature from room temperature to 80~90℃ and hold for 1~2h, the heating rate is 2℃ / min to raise the temperature from 80~90℃ to 115~125℃ and hold for 4~6h, the cooling rate is 2℃ / min to lower the temperature from 115~125℃ to 70~80℃ and hold for 3~4h, and the temperature is lowered to room temperature at 1℃ / min. The ultra-high molecular weight polyethylene three-dimensional product is obtained by cooling.

Images