Polymer composites, and methods for preparing and using same - Patents.com

Abstract

The present invention discloses a polymer composite, its preparation method and use. The polymer composite comprises, by weight, 100 parts of polymer powder, 0.1-3 parts of nanoparticle A and 0.05-1.5 parts of nanoparticle B, where the particle size of nanoparticle A is smaller than that of nanoparticle B, and the mass ratio of nanoparticle A to nanoparticle B is (1-9):1. The present invention uses small and large nanoparticles in a specific ratio, which cooperate with each other as a flow agent for polymer powder, so that the polymer composite has excellent flowability, permeability and high temperature stability.

Description

[Technical Field]

[0001] This application relates to the technical field of polymeric materials, and in particular to polymer composites, and methods for their preparation and use. [Background technology]

[0002] Polymer materials are high-molecular-weight compounds composed of many similar, simple structural units repeatedly linked by covalent bonds. Polymer powders are fine chemicals with a specific particle size, distribution, and morphology, prepared by chemical or physical methods. Polymer powders are widely used in fields such as powder coatings, 3D printing, cosmetics, additives, and pharmaceuticals.

[0003] Polymer powders can be prepared by chemical synthesis methods, such as suspension polymerization or emulsion polymerization, but the preparation process is complicated and there are limitations on the types of polymers, and in many cases only styrene or acrylic acid (ester) polymers can be prepared. Currently, the main means of obtaining polymer powders is still mechanical grinding, which has the advantage of being simple and capable of continuous production, but the prepared particles have random and disordered shapes and a wide particle size distribution.

[0004] The two methods mentioned above are commonly used to prepare polymer powders. However, the powders prepared by these methods tend to have irregular shapes and poor flowability, which is crucial for the use of polymer powders. Currently, methods to improve the flowability of polymer powders mainly involve reducing the interfacial force between particles (e.g., by adding a flow aid or coating the polymer) or reducing rolling resistance (e.g., by modifying the particle shape of the polymer, e.g., to make it spherical). Furthermore, polymers have limited temperature resistance, and as the operating temperature increases, the flowability of the powder decreases, limiting its range of use. In the first method, the mixing process of the flow aid can be carried out in any suitable mixing equipment, including fluidized beds and various drums or mixers equipped with one or more rotating shafts.

[0005] CN1102954C discloses a method for preparing a particulate detergent composition, which comprises adding percarbonate having an average particle size in the range of 250 to 900 microns and a powder flow aid of partially hydrated crystalline sodium aluminosilicate to powder particles of the particulate detergent.

[0006] CN109929242A discloses a nylon polymer powder endothermic material and a method for preparing it. The disclosed preparation method includes the steps of adding nylon raw material, a molecular weight regulator, and deionized water to a polymerization reactor, reducing the pressure inside the reactor to atmospheric pressure, adding a heat transfer medium, stirring, stringing, and cutting to obtain nylon heat transfer medium pellets, adding the nylon heat transfer medium pellets to a post-shrink barrel, heating and vacuum suction stirring to obtain nylon heat transfer medium polycondensation pellets, cryogenically grinding the nylon heat transfer medium polycondensation pellets to obtain nylon heat transfer medium powder material, adding 20 parts of the nylon heat transfer medium powder material and 0.1 to 2 parts of carbon black to a stirring can and stirring at high speed to obtain a nylon-carbon black mixed powder material, and adding the nylon-carbon black mixed powder material, a flow aid, and 80 parts of the nylon heat transfer medium powder material to a powder mixing can and stirring at high speed and sieving to obtain a nylon polymer powder endothermic material. The disclosed method provides good surface quality and mechanical performance of products applied to fiber laser sintering of nylon polymer powder.

[0007] CN108727814A discloses a composite nylon powder material for selective laser sintering and its preparation method. The disclosed composite nylon powder material contains, by weight, 30-70 parts nylon resin powder, 30-50 parts hollow glass microbeads, 0-20 parts glass fiber, 0.2-2 parts coupling agent, 0.1-1.5 parts flow aid, and 0.2-2 parts antioxidant. The addition of the disclosed modified glass fiber and hollow glass microbeads to nylon resin powder, compared with simply adding glass fiber, results in a nylon composite powder containing both hollow glass microbeads and glass fiber with better flowability, better powder spreading, and a higher strength modulus of the sintered material. Therefore, nylon composites containing hollow glass microbeads and glass fiber expand the application fields of nylon.

[0008] Currently, there is a limit to how much polymer flow can be improved by reducing particle interfacial forces and rolling resistance, so it is very important to develop polymer materials with excellent flowability. Summary of the Invention

[0009] The following is a general overview of the subject matter described in detail in this application, which is not intended to limit the scope of protection of the claims.

[0010] In response to the deficiencies in the prior art, the present application aims to provide a polymer composite having excellent flowability, permeability and high temperature stability, as well as a method for preparing and using the same.

[0011] To achieve this goal, the present application adopts the following technical solutions.

[0012] In a first aspect, the present application provides a polymer composite comprising, by weight, 100 parts polymer powder, 0.1 to 3 parts nanoparticles A, and 0.05 to 1.5 parts nanoparticles B, The particle size of nanoparticle A is smaller than that of nanoparticle B, The polymer composite is provided, wherein the mass ratio of the nanoparticles A to the nanoparticles B is (1-9):1, where 1-9 may be 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, etc.

[0013] The polymer composite of the present application comprises nanoparticles A and B in a specific mass ratio that act together as a flow agent for the polymer powder, which are coated on the surface of the polymer powder, reducing the surface friction of the particles and the inter-particle forces, thereby improving the flowability, permeability, and stability at high temperatures of the polymer powder.

[0014] The weight part of the nanoparticles A is 0.1 to 3 parts, for example, 0.2 parts, 0.5 parts, 0.8 parts, 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2 parts, 2.2 parts, 2.4 parts, 2.6 parts, 2.8 parts, etc.

[0015] The weight part of the nanoparticles B is 0.05 to 1.5 parts, for example, 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, etc.

[0016] Preferably, the mass ratio of the nanoparticles A to the nanoparticles B is (1.5 to 4): 1. However, 1.5 to 4 may also be 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, or the like.

[0017] The mass ratio of nanoparticles A to nanoparticles B according to the present invention is preferably (1.5 to 4):1, and when the mass ratio is in this range, the resulting polymer composite has better fluidity and high-temperature stability.

[0018] Preferably, the particle size of the nanoparticles A is 5 to 50 nm, for example, 6 nm, 8 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 42 nm, 45 nm, 48 nm, etc., and is preferably 5 to 30 nm.

[0019] The particle size of the nanoparticles A according to the present invention is preferably 5 to 30 nm, because small nanoparticles can form a dense coating on the surface of the polymer, thereby reducing the interparticle force.

[0020] Preferably, the particle size of the nanoparticles B is 50 to 600 nm, for example, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, etc., and is preferably 50 to 300 nm.

[0021] The particle size of the nanoparticles B according to the present invention is preferably 50 to 300 nm, because large nanoparticles create rolling friction and a barrier effect on the surface of the polymer, reducing the interparticle force.

[0022] Preferably, the median diameter of the polymer powder is 5 to 500 μm, for example, 10 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, etc., preferably 10 to 300 μm, more preferably 50 to 150 μm.

[0023] Preferably, the polymer powder comprises a thermoplastic polymer powder and / or a thermosetting polymer powder.

[0024] Preferably, the polymer powder comprises a thermoplastic polymer powder.

[0025] Preferably, the thermoplastic polymer powder comprises a combination of at least one of a thermoplastic elastomer, a polyamide, a polyolefin, a polymethacrylate, a polycarbonate, or a polystyrene, although typical combinations include, but are not limited to, a combination of a thermoplastic elastomer and a polyamide, a combination of a polyolefin, a polymethacrylate, and a polycarbonate, or a combination of a polyamide, a polyolefin, a polymethacrylate, a polycarbonate, and a polystyrene.

[0026] Preferably, the nanoparticles A comprise one or a combination of at least two of nanosilica, nanotitanium dioxide, and nanosilicon carbide, although typical combinations include, but are not limited to, a combination of nanosilica and nanotitanium dioxide, a combination of nanotitanium dioxide and nanosilicon carbide, or a combination of nanosilica, nanotitanium dioxide, and nanosilicon carbide.

[0027] Preferably, the nanoparticles B comprise one or a combination of at least two of nanosilica, nanotitanium dioxide, nanosilicon carbide, nanoaluminum oxide, talc powder, magnesium stearate, and magnesium oxide, although typical combinations include, but are not limited to, a combination of nanosilica and nanotitanium dioxide, a combination of nanotitanium dioxide, nanosilicon carbide, and nanoaluminum oxide, and a combination of nanoaluminum oxide, talc powder, magnesium stearate, and magnesium oxide.

[0028] In a second aspect, the present application provides a method for preparing a polymer composite as described in the first aspect, comprising: The preparation method includes the steps of first stirring and mixing a polymer powder and nanoparticles A, then second stirring and mixing the mixed raw materials and nanoparticles B, and sieving the mixture to obtain the polymer composite.

[0029] In the present invention, in the process of preparing the polymer composite, it is preferred to mix the polymer powder with nanoparticles A, which have a smaller particle size, to achieve a more dense coating on the particle surface. However, since nanoparticles B have a larger particle size, mixing nanoparticles B first will affect the coating of the smaller nanoparticles on the surface of the polymer powder.

[0030] Preferably, the time for the first stirring and mixing is 1 to 15 minutes, for example, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, etc., and preferably 1 to 3 minutes.

[0031] Preferably, the time for the second stirring and mixing is 1 to 6 minutes, for example, 1.5 minutes, 2 minutes, 2.5 minutes, 3 minutes, 3.5 minutes, 4 minutes, 4.5 minutes, 5 minutes, 5.5 minutes, etc., and preferably 1 to 2 minutes.

[0032] The stirring and mixing in this application is continuous stirring and mixing. If the mixing time is insufficient, the polymer powder and the nanoparticles cannot be mixed uniformly; if the mixing time is too long, the nanoparticles will be lost and embedded, resulting in the loss of the effect of the composite nanoparticles.

[0033] Preferably, the sieving is carried out with a sieve.

[0034] Preferably, the mesh number of the sieve is 50 to 300 mesh, for example, 60 mesh, 80 mesh, 100 mesh, 120 mesh, 140 mesh, 160 mesh, 180 mesh, 200 mesh, 220 mesh, 240 mesh, 260 mesh, etc. The mesh number of the sieve is 50 to 300 mesh, and the particle size of the particles sieved by the sieve is 30 to 500 mesh.

[0035] As a preferred technical solution, the preparation method comprises: The method includes the steps of first stirring and mixing the polymer powder and nanoparticles A for 1 to 15 minutes, then stirring and mixing the mixed raw materials and nanoparticles B for 1 to 6 minutes for a second time, and finally sieving the mixture through a sieve with a mesh number of 50 to 300 to obtain the polymer composite.

[0036] In a third aspect, the present application provides the use of a polymer composite according to the first aspect in powder coating or 3D printing.

[0037] Compared with the prior art, the present application has the following beneficial effects:

[0038] The small nanoparticles and large nanoparticles used in this application are blended in a specific ratio and work together as a flow agent for polymer powder, resulting in a polymer composite with excellent flowability, permeability, and high-temperature stability. For example, if the polymer powder is thermoplastic polyurethane, the polymer composite has an SE flow energy of 7.75 mJ / g or less, an FRI of 1.35 or less, and a permeability of 4.11 mbar or more.

[0039] Other aspects may be appreciated upon reading and understanding the detailed description. [Brief explanation of the drawings]

[0040] [Figure 1] 1 is a scanning electron micrograph of the polymer composite described in Example 1. [Figure 2] 1 is a scanning electron micrograph of the polymer composite described in Example 1 after heating at 100° C. [Figure 3] 1 is a scanning electron micrograph of the polymer composite described in Example 2. [Figure 4] 1 is a scanning electron micrograph of the polymer composite described in Example 2 after heating at 135° C. [Figure 5] 1 is a scanning electron micrograph of the polymer composite described in Example 3. [Figure 6] 1 is a scanning electron micrograph of the polymer composite described in Example 4. [Figure 7] 1 is a scanning electron micrograph of the polymer composite described in Example 6. [Figure 8] 1 is a scanning electron micrograph of the polymer composite described in Example 8. [Figure 9] 1 is a scanning electron micrograph of the polymer composite described in Comparative Example 1. [Figure 10] 1 is a scanning electron micrograph of the polymer composite described in Comparative Example 1 after heating at 100° C. [Figure 11] 1 is a scanning electron micrograph of the polymer composite described in Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0041] In order to facilitate understanding of the present application, the present application provides the following examples as examples. Those skilled in the art should understand that the above examples are only for understanding the present application and are not intended to specifically limit the present application.

[0042] Example 1 This example provides a polymer composite consisting of the following components, in parts by weight: 100 parts polymer powder, 0.3 parts nanoparticles A, and 0.13 parts nanoparticles B.

[0043] The polymer powder is cryogenically ground thermoplastic polyurethane, with a median diameter of 65 μm and a hardness of Shore A 90. The raw material is purchased from Wanhua Chemical Group Co., Ltd., model number WHT-1490IV.

[0044] Nanoparticle A: Nanosilica, particle size is 12 nm. Nanoparticle B: Nanosilica, particle size 50 nm.

[0045] The method for preparing the polymer composite includes the following steps:

[0046] The polymer powder and nanoparticles A were mixed for the first time for 2 minutes, and then the mixed raw materials and nanoparticles B were mixed for the second time for 1 minute. Finally, the mixture was sieved through a 50-mesh sieve to obtain the polymer composite.

[0047] Example 2 This example provides a polymer composite consisting of the following components, in parts by weight: 100 parts polymer powder, 0.5 parts nanoparticles A, and 0.33 parts nanoparticles B.

[0048] The polymer powder is cryogenically ground polypropylene, with a median diameter of 50 μm. The raw material is purchased from Wanhua Chemical Group Co., Ltd., and the model number is WANFAB GP1000. Nanoparticle A: nano silicon carbide, particle size 5 nm. Nanoparticle B: nano aluminum oxide, particle size 80 nm.

[0049] The method for preparing the polymer composite includes the following steps:

[0050] The polymer powder and nanoparticles A were mixed for the first time for 3 minutes, and then the mixed raw materials and nanoparticles B were mixed for the second time for 2 minutes. Finally, the mixture was sieved through a 70-mesh sieve to obtain the polymer composite.

[0051] Example 3 This example provides a polymer composite consisting of the following components, in parts by weight: 100 parts polymer powder, 3 parts nanoparticles A, and 0.75 parts nanoparticles B.

[0052] The polymer powder is a cryogenically crushed phenolic resin, the median diameter is 5 μm, and the raw material model number is 2123 phenolic resin. Nanoparticle A: nano titanium dioxide, particle size 5 nm. Nanoparticle B: nano silicon carbide, particle size 50 nm.

[0053] The method for preparing the polymer composite includes the following steps:

[0054] The polymer powder and nanoparticles A were mixed for the first time for 15 minutes, and then the mixed raw materials and nanoparticles B were mixed for the second time for 6 minutes. Finally, the mixture was sieved through a 300-mesh sieve to obtain the polymer composite.

[0055] Example 4 This example provides a polymer composite consisting of the following components, in parts by weight: 100 parts polymer powder, 0.2 parts nanoparticles A, and 0.06 parts nanoparticles B.

[0056] The polymer powder is cryogenically ground thermoplastic polyurethane, with a median diameter of 500 μm and a hardness of Shore A 90. The raw material is purchased from Wanhua Chemical Group Co., Ltd., model number WHT-1490IV. Nanoparticle A: Nanosilica, particle size 50 nm. Nanoparticles B: talc powder, particle size 600 nm.

[0057] The method for preparing the polymer composite includes the following steps:

[0058] The polymer powder and nanoparticles A were mixed for the first time for 1 minute, and then the mixed raw materials and nanoparticles B were mixed for the second time for 1 minute. Finally, the mixture was sieved through a 50-mesh sieve to obtain the polymer composite.

[0059] Example 5 This example provides a polymer composite consisting of the following components, in parts by weight: 100 parts polymer powder, 0.1 parts nanoparticles A, and 0.05 parts nanoparticles B.

[0060] The polymer powder is cryogenically ground thermoplastic polyurethane, with a median diameter of 150 μm and a hardness of Shore A 90. The raw material is purchased from Wanhua Chemical Group Co., Ltd., model number WHT-1490IV. Nanoparticle A: nano titanium dioxide, particle size 30 nm. Nanoparticles B: talc powder, particle size 300 nm.

[0061] The method for preparing the polymer composite includes the following steps:

[0062] The polymer powder and nanoparticles A were mixed for the first time for 1 minute, and then the mixed raw materials and nanoparticles B were mixed for the second time for 2 minutes. Finally, the mixture was sieved through a 60-mesh sieve to obtain the polymer composite.

[0063] Example 6 This example provides a polymer composite consisting of the following components, in parts by weight: 100 parts polymer powder, 2 parts nanoparticles A, and 0.75 parts nanoparticles B.

[0064] The polymer powder is cryogenically ground thermoplastic polyurethane, with a median diameter of 10 μm and a hardness of Shore A 90. The raw material is purchased from Wanhua Chemical Group Co., Ltd., model number WHT-1490IV. Nanoparticle A: nano silicon carbide, particle size 5 nm. Nanoparticle B: Nanosilica, particle size 50 nm.

[0065] The method for preparing the polymer composite includes the following steps:

[0066] The polymer powder and nanoparticles A were mixed for the first time for 1.5 min, and then the mixed raw materials and nanoparticles B were mixed for the second time for 1 min. Finally, the mixture was sieved through a 300 mesh sieve to obtain the polymer composite.

[0067] Example 7 This example provides a polymer composite consisting of the following components, in parts by weight: 100 parts polymer powder, 2 parts nanoparticles A, and 0.5 parts nanoparticles B.

[0068] The polymer powder is cryogenically ground thermoplastic polyurethane, with a median diameter of 300 μm and a hardness of Shore A 90. The raw material is purchased from Wanhua Chemical Group Co., Ltd., model number WHT-1490IV. Nanoparticles A: 1 part nanosilica, particle size 35 nm, 1 part nanotitanium dioxide, particle size 35 nm. Nanoparticles B: 0.25 parts nano silicon carbide, particle size 150 nm, 0.25 parts nano aluminum oxide, particle size 150 nm.

[0069] The method for preparing the polymer composite includes the following steps:

[0070] The polymer powder and nanoparticles A were mixed for the first time for 2 minutes, and then the mixed raw materials and nanoparticles B were mixed for the second time for 2 minutes. Finally, the mixture was sieved through a 50-mesh sieve to obtain the polymer composite.

[0071] Example 8 This example provides a polymer composite consisting of the following components, in parts by weight: 100 parts polymer powder, 1 part nanoparticles A, and 0.3 parts nanoparticles B.

[0072] The polymer powder is cryogenically ground polypropylene, with a median diameter of 80 μm. The raw material is purchased from Wanhua Chemical Group Co., Ltd., and the model number is WANFAB GP1000. Nanoparticles A: 0.5 parts nanosilica, particle size 15 nm, 0.5 parts nanosilicon carbide, particle size 15 nm. Nanoparticles B: 0.15 parts nano silicon carbide, particle size 100 nm, 0.15 parts nano silica, particle size 100 nm.

[0073] The method for preparing the polymer composite includes the following steps:

[0074] The polymer powder and nanoparticles A were mixed for the first time for 2 minutes, and then the mixed raw materials and nanoparticles B were mixed for the second time for 3 minutes. Finally, the mixture was sieved through a 60-mesh sieve to obtain the polymer composite.

[0075] Examples 9 to 12 The difference between Examples 9 to 12 and Example 1 is that the mass ratio of nanoparticles A to nanoparticles B is different, and the total mass of nanoparticles A and nanoparticles B is 0.6 parts. Examples 9 to 12 are all the same as Example 1, except that the mass ratio of nanoparticles A to nanoparticles B is 9:1 (Example 9), 1:1 (Example 10), 4:1 (Example 11), and 1.5:1 (Example 12), respectively.

[0076] Examples 13 to 16 The difference between Examples 13 to 16 and Example 1 is that the particle diameter of nanoparticles A is 5 nm (Example 13), 50 nm (Example 14), 3 nm (Example 15), and 60 nm (Example 16), respectively; otherwise, they are the same as Example 1.

[0077] Examples 17 to 19 Examples 17 to 19 are different from Example 1 in that the particle diameter of nanoparticles B is 600 nm (Example 17), 30 nm (Example 18), and 700 nm (Example 19).

[0078] Comparative Example 1 This comparative example provides a polymer composite consisting of the following components, by weight: 100 parts polymer powder, 0.5 parts small particle size nanoparticles.

[0079] The polymer powder is cryogenically ground thermoplastic polyurethane, with a median diameter of 60 μm and a hardness of Shore A 90. The raw material is purchased from Wanhua Chemical Group Co., Ltd., model number WHT-1490IV. Small particle size nanoparticles: nanosilica, particle size 15 nm.

[0080] The method for preparing the polymer composite includes the following steps:

[0081] The polymer powder and the small particle size nanoparticles were mixed for 2 minutes and then sieved through a 50 mesh sieve to obtain the polymer composite.

[0082] Comparative Example 2 This comparative example provides a polymer composite consisting of the following components, by weight: 100 parts polymer powder, 0.7 parts large size nanoparticles.

[0083] The polymer powder is cryogenically ground thermoplastic polyurethane, with a median diameter of 80 μm and a hardness of Shore A 90. The raw material is purchased from Wanhua Chemical Group Co., Ltd., model number WHT-1490IV. Large particle size nanoparticles: nanosilica, particle size 100 nm.

[0084] The method for preparing the polymer composite includes the following steps:

[0085] The polymer powder and the large-sized nanoparticles were mixed for 3 minutes, and then sieved through an 80-mesh sieve to obtain the polymer composite.

[0086] Comparative Examples 3 and 4 The difference between Comparative Examples 3 and 4 and Example 1 is that the mass ratio of nanoparticles A to nanoparticles B is different, and the total mass of nanoparticles A and nanoparticles B is 0.6 parts. Comparative Examples 3 and 4 are all the same as Example 1, except that the mass ratios of nanoparticles A to nanoparticles B are 10:1 and 1:4, respectively.

[0087] Performance Test The polymer composites described in Examples 1 to 19 and Comparative Examples 1 to 4 were measured as follows.

[0088] (1) Flow performance: After the sample was thoroughly dried, it was measured using a Freeman FT4 powder rheometer. After turning on the test software, the required test method, "stability and variable flow rate," was selected to measure the flow performance. The measurement results included the flow activation energy and the permeability (1-15 kPa) of the sample. The measurement results also included the pressure loss (1-15 kPa). Finally, the data was processed.

[0089] (2) Bulk density: Measured using a Baxter BT-1000 powder property tester. The density container was cleaned thoroughly and kept dry inside. The density meter was then adjusted horizontally, and the funnel nozzle was adjusted 40 mm from the upper edge of the density cup. The powder property tester was turned on, and a 100 m bulk density container was attached.

[0090] A 100 g powder sample was weighed and placed in the upper funnel of the tester, and the funnel outlet was blocked.

[0091] Quickly open the funnel outlet, allow the sample in the funnel to fall vertically into the density container under natural conditions, scrape off excess sample from the top of the density cup with a spatula, tap the density cup lightly to fix the sample, record the mass M of the powder in the container, and measure the deposited density ρ (g / cm 3 )=M1 / 100.

[0092] Measurements were performed multiple times to ensure reproducibility of the results, and the measurement results are summarized in Table 1. [Table 1]

[0093] As can be seen from the data in Table 1, for example, using thermoplastic polyurethane as the polymer powder, the polymer composite had an SE flow energy of 7.75 mJ / g or less, an FRI of 1.35 or less, and a permeability of 4.11 mbar or more. The polymer composite of the present invention uses small and large nanoparticles in combination as a flow agent for the polymer powder. The cohesive property index FRI and SE flow energy of the polymer composite, a mixture of the three, were low, demonstrating that the combination of small and large nanoparticles effectively reduces the flow resistance of the polymer powder. Furthermore, the permeability pressure drop of the polymer composite was significantly higher, indicating a tighter powder stack with fewer interparticle gaps. This is consistent with the results of the stack density. The BFE flow energy comprehensively indicated the stack density and the powder cohesive properties. Powders with higher stack density and better cohesive properties tended to require more energy to drive the powder rheometer blade and had a higher BFE. Therefore, the polymer composite of the present invention had excellent flowability and permeability.

[0094] As can be seen from the analysis of Comparative Examples 1-2 and Example 1, the deposition density in Comparative Example 2 is relatively high due to the selection of a large particle size powder. However, since the deposition density is not as sensitive to flowability as the particle size, it can be inferred that the performance of Comparative Examples 1-2 is still inferior to that of Example 1. This proves that the nanoparticles A and B used work together as a flow agent for the polymer powder to form a polymer composite with excellent flowability and high temperature stability.

[0095] As can be seen from the analysis of Comparative Examples 3-4 and Examples 9-10, the performance of Comparative Examples 3-4 was inferior to that of Examples 9-10, which proved that the performance of the obtained polymer composite was better when the mass ratio of nanoparticles A to nanoparticles B was within the range of (1-9):1.

[0096] As can be seen from the analysis of Examples 9 to 12, the performance of Examples 9 to 10 was inferior to that of Examples 11 to 12, and it was proven that the mass ratio of nanoparticles A to nanoparticles B was preferably (1.5 to 4:1), and the performance of the obtained polymer composite was better.

[0097] As can be seen from the analysis of Examples 13 to 16, the performance of Examples 15 to 16 was inferior to that of Examples 13 to 14, demonstrating that if the particle size of nanoparticles A is in the range of 5 to 50 nm, it can cooperate better with nanoparticles B to improve the performance of the polymer composite.

[0098] As can be seen from the analysis of Examples 17-19 and Example 1, the performance of Examples 18-19 was inferior to that of Examples 1 and 17, demonstrating that if the particle size of nanoparticles B is in the range of 50-600 nm, it can cooperate better with nanoparticles A to improve the performance of the polymer composite.

[0099] As can be seen from comparing Figures 1 and 2, in Figure 1, nanoparticles B and A were uniformly distributed in the polymer powder substrate. In Figure 2, after heating at 100°C, nanoparticles B and A were still uniformly distributed in the polymer powder substrate, with no loss or embedding. This demonstrates that the polymer composite of the present invention has excellent high-temperature stability. Comparing Figures 3 and 4 reveals similar results.

[0100] Comparing Figures 9 and 10, it can be seen that in Figure 9, a single type of nanoparticles is uniformly distributed in the polymer powder substrate, whereas after heating, the nanoparticles in Figure 10 appear to be obviously embedded and lost, which affected the heat resistance and high-temperature fluidity of the polymer composite.

[0101] Therefore, the polymer composite formed after mixing nanoparticles A and nanoparticles B in a specific blending ratio with polymer powder had excellent fluidity and high-temperature thermal stability.

[0102] As can be seen from the analysis of Figures 5 to 8, by appropriately adjusting the particle size and type of nanoparticles A, nanoparticles B, and polymer powder, the resulting polymer composite exhibits excellent fluidity and isothermal thermal stability. Although scanning electron micrographs after high-temperature heating are not provided in this application, it is estimated from the results of Examples 1 and 2 and Comparative Example 1 that Examples 3, 4, 6, and 8 would also exhibit similar results. That is, the polymer composite formed by combining nanoparticles A and nanoparticles B in a specific blending ratio and mixing them with polymer powder exhibits excellent fluidity and high-temperature thermal stability. Figure 11 shows that the nanoparticles are uniformly distributed, suggesting that similar results to Comparative Example 1 would be obtained. That is, nanoparticles of a single particle size type have limitations in improving the performance of the polymer powder, particularly its high-temperature stability and fluidity. Some of the embodiments of the invention related to the present invention are shown below. [Embodiment 1] A polymer composite comprising, in parts by weight, 100 parts polymer powder, 0.1 to 3 parts nanoparticles A, and 0.05 to 1.5 parts nanoparticles B, The particle size of nanoparticle A is smaller than that of nanoparticle B, A polymer composite, wherein the mass ratio of nanoparticles A to nanoparticles B is (1-9):1. [Embodiment 2] 2. The polymer composite of embodiment 1, wherein the mass ratio of nanoparticles A to nanoparticles B is (1.5-4):1. [Embodiment 3] 3. The polymer conjugate of embodiment 1 or 2, wherein the particle size of the nanoparticles A is 5 to 50 nm. [Embodiment 4] 3. The polymer composite of embodiment 1 or 2, wherein the particle size of the nanoparticles B is 50 to 600 nm. [Embodiment 5] 5. The polymer composite according to any one of embodiments 1 to 4, wherein the polymer powder has a median diameter of 5 to 500 μm. [Embodiment 6] the polymer powder comprises a thermoplastic polymer powder and / or a thermosetting polymer powder; Preferably, the polymer powder comprises a thermoplastic polymer powder; Preferably, the thermoplastic polymer powder comprises any one or a combination of at least two of a thermoplastic elastomer, a polyamide, a polyolefin, a polymethacrylate, a polycarbonate or a polystyrene; Preferably, the nanoparticles A comprise any one or a combination of at least two of nanosilica, nanotitanium dioxide, or nanosilicon carbide; 6. The polymer composite of any one of embodiments 1 to 5, wherein the nanoparticles B comprise any one or a combination of at least two of nanosilica, nanotitanium dioxide, nanosilicon carbide, nanoaluminum oxide, talc powder, magnesium stearate, or magnesium oxide. [Embodiment 7] A method for preparing the polymer composite of any one of embodiments 1 to 6, comprising: The preparation method includes a step of first stirring and mixing a polymer powder and nanoparticles A, then stirring and mixing the mixed raw materials and nanoparticles B for a second time, and sieving the mixture to obtain the polymer composite. [Embodiment 8] The first stirring and mixing time is 1 to 15 minutes, Preferably, the second stirring and mixing time is 1 to 6 minutes. [Embodiment 9] The sieving is performed using a sieve, The method of any one of embodiments 7 to 8, wherein the mesh number of the sieve is preferably 50 to 300 mesh. [Embodiment 10] 10. The method of any one of embodiments 7 to 9, comprising the steps of: first stirring and mixing the polymer powder and nanoparticles A for 1 to 15 minutes; then second stirring and mixing the mixed raw materials and nanoparticles B for 1 to 6 minutes; and finally sieving the mixture through a sieve with a mesh number of 50 to 300 mesh to obtain the polymer composite. [Embodiment 11] Use of the polymer composite of any one of embodiments 1 to 6 in powder coatings or 3D printing.

Claims

1. A polymer composite consisting solely of, in parts by weight, 100 parts polymer powder, 0.1 to 3 parts nanoparticles A and 0.05 to 1.5 parts nanoparticles B, The particle size of nanoparticle A is smaller than that of nanoparticle B, the mass ratio of the nanoparticles A to the nanoparticles B is (1.5 to 4):1; the polymer powder comprises any one or a combination of at least two of a thermoplastic elastomer, a polyamide, a polyolefin, a polymethacrylate, a polycarbonate, or a polystyrene; The polymer composite is a polymer composite used for 3D printing.

2. 2. The polymer composite of claim 1, wherein the nanoparticles A have a particle size of 5 to 50 nm.

3. 3. The polymer composite according to claim 1, wherein the particle size of the nanoparticles B is 50 to 600 nm.

4. The polymer composite according to any one of claims 1 to 3, wherein the polymer powder has a median diameter of 5 to 500 µm.

5. The nanoparticles A comprise any one or a combination of at least two of nanosilica, nanotitanium dioxide, or nanosilicon carbide; The polymer composite according to any one of claims 1 to 4, wherein the nanoparticles B comprise any one or a combination of at least two of nanosilica, nanotitanium dioxide, nanosilicon carbide, nanoaluminum oxide, talc powder, magnesium stearate, or magnesium oxide.

6. A method for preparing the polymer composite of any one of claims 1 to 5, comprising the steps of: The preparation method includes a step of first stirring and mixing a polymer powder and nanoparticles A, then stirring and mixing the mixed raw materials and nanoparticles B for a second time, and sieving the mixture to obtain the polymer composite.

7. The preparation method according to claim 6, wherein the first stirring and mixing time is 1 to 15 minutes.

8. The preparation method described in claim 6, wherein the second stirring and mixing time is 1 to 6 minutes.

9. 9. The method according to claim 7 or 8, wherein the sieving is carried out by means of a sieve.

10. The preparation method described in Claim 9, wherein the mesh number of the sieve is 50 to 300 mesh.

11. The method according to any one of claims 7 to 10, comprising the steps of: first stirring and mixing the polymer powder and nanoparticles A for 1 to 15 minutes; then secondly stirring and mixing the mixed raw materials and nanoparticles B for 1 to 6 minutes; and finally sieving the mixture through a sieve with a mesh number of 50 to 300 mesh to obtain the polymer composite.

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