A fiber-reinforced polymer 3D printed foamed part and its application

Abstract

The present invention discloses a fiber-reinforced polymer 3D printed foamed part and its application, and relates to the technical field of 3D printing. The fiber-reinforced polymer 3D printed foamed part provided by the present invention is a polymer particle containing a foaming agent formed by compounding fibers with specific structural characteristics with a foaming agent and a polymer. The composite particles have excellent deformation ability. After a specific melt extrusion-3D printing stacking process, a 3D printed part with both high precision and high strength can be obtained. The dimensional error of the obtained part is as low as less than 3%, and the tensile breaking strength is as high as more than 40N. Compared with the foamed part without fiber reinforcement, the tensile breaking strength is increased by more than 100%, and it has the characteristics of lightweight, with a density of ≤0.85g / cm <supgt;3< / supgt;。

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing, and in particular to a fiber-reinforced polymer 3D printed foamed part and an application thereof. Background Art

[0002] As the requirements for the structure of polymer parts increase, 3D printing technology with excellent structural design freedom has also received more and more attention. However, existing 3D printed parts are usually solid structures, resulting in high density and heavy weight, which limits their application. In order to reduce the weight of existing 3D parts, foaming them after the parts are obtained by 3D printing is a feasible way, because foaming can make the parts rich in pores, with lower weight and density at the same volume. However, foaming after the 3D printed parts are obtained has problems such as difficulty in controlling the size of the parts. This problem can be solved by adjusting the process sequence and stacking the foamed melt in a controllable manner to form a 3D printed part. However, the presence of the pore structure will significantly reduce the strength of the printed parts, and the higher the degree of foaming and expansion of the material, the lower the strength of the part, which also limits the application of 3D printed foamed parts. In order to improve the strength of the foamed parts, fibers can be introduced into the melt, but the introduction of fibers will lead to a decrease in the precision of the parts. Therefore, it is urgent to find a preparation process that can take into account both the strength and dimensional accuracy of 3D printed foam parts. Summary of the invention

[0003] In order to address the deficiencies of the prior art, the present invention provides a fiber-reinforced polymer 3D printed foamed part, in which fibers with specific structural characteristics are mixed with a foaming agent and a polymer to form polymer particles containing a foaming agent. The composite particles have excellent deformation ability, and after a specific melt extrusion-3D printing stacking process, a 3D printed part with both high precision and high strength can be obtained.

[0004] Another object of the present invention is to provide a foamed shoe material.

[0005] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0006] A fiber-reinforced polymer 3D printed foamed part, which is prepared by melt extrusion foaming and 3D stacking of the foamed melt using polymer particles containing a foaming agent as a preparation raw material, wherein the polymer particles containing a foaming agent also contain fibers, wherein the content of the fibers in the polymer particles containing a foaming agent is 0.1-10 wt%, the diameter is 0.1-20 μm, and the aspect ratio is 5-25;

[0007] The melt extrusion is performed by a single screw extruder, which includes a first heating section, a second heating section, and a third heating section in sequence. The temperature of the first heating section is 0-30°C, the temperature of the second heating section is 160-320°C, and the temperature of the third heating section is 230-390°C, wherein the real-time temperature of the third heating section is higher than the temperature of the second heating section.

[0008] In a specific embodiment of the present invention, the fiber has a diameter of 0.1-20 μm, an aspect ratio of 5-25, and a length of 0.5-500 μm.

[0009] In the fiber-reinforced polymer 3D printed foamed parts provided by the present invention, the high strength of the fiber makes it possible to improve the strength of the polymer foamed parts. The inventors of the present application have found through a large number of experimental studies that after adding fibers to polymer particles containing a foaming agent and performing melt extrusion and 3D printing stacking, the fiber diameter, aspect ratio, addition amount and parameters of the melt extrusion process will affect the expansion behavior and stacking behavior of the polymer foam melt formed by melt extrusion, and will also affect the deformation ability of the foam melt, thereby affecting the accuracy and strength of the foamed printed parts. By adjusting the above parameters, the deformation ability of the polymer / fiber foam melt can be within a suitable range, while having more suitable expansion behavior and stacking behavior. Under the premise that the extrusion process is limited to three-stage extrusion and the temperatures are limited to 0~30℃, 160~320℃ and 230~390℃ respectively, when the fiber addition amount is higher than 10 wt%, due to the rapid increase of the interface between the fiber and the polymer matrix, the foaming agent is easy to escape quickly from the gap between the fiber and the polymer matrix at the feed section and the extrusion die of the extruder, resulting in a decrease in the expansion degree of the foaming melt, an increase in the size of the bubbles and a decrease in the density of the bubbles, affecting the surface quality of the foamed printed parts and reducing the accuracy of the obtained parts; at the same time, if the diameter of the fiber is too large or the aspect ratio is too long, it will affect the stacking of the foaming melt, especially when the printing accuracy is higher (the 3D printed parts are required to have smaller "pixel points"), which will cause the 3D printing unit to be too large, thereby reducing the printing accuracy.

[0010] In a specific embodiment of the present invention, the melt extrusion-3D printing stacking process is carried out in a 3D printing device in which the wire extrusion unit is an extruder, and the 3D printing device includes: a feeding unit, a micro-extrusion unit, a printer motion bracket, a stacking platform, and a printer housing. More specifically, the melt extrusion-3D printing stacking process in the above-mentioned 3D printing device comprises the following steps: after the polymer particles containing the foaming agent are put into the feeding unit, they are melt-extruded through the micro-extrusion unit, and then the foaming wire melt extruded from the die of the micro-extrusion unit is stacked on the stacking platform under the action of the printer motion bracket, so as to obtain a fiber-reinforced polymer 3D printed foamed part.

[0011] In a specific embodiment of the present invention, the chamber temperature of the 3D printing device is 30-100° C., preferably 40-90° C., and the temperature control accuracy is 1-5° C., preferably 1-3° C. In a specific embodiment of the present invention, the printing temperature (extrusion die temperature) of the 3D printing stack is consistent with the chamber temperature of the 3D printing device.

[0012] In a specific embodiment of the present invention, the residence time of the polymer particles containing the foaming agent in the second heating section and / or the third heating section is 0.1 to 1.5 s, preferably 0.2 to 1.0 s, and more preferably 0.3 to 0.8 s.

[0013] In a specific embodiment of the present invention, the temperature control accuracy of the single screw extruder is 0.5~5°C, preferably 1~3°C.

[0014] In a specific embodiment of the present invention, the 3D printing stacking is performed under the condition of a rotation angle of 0 to 80°, preferably 0 to 70°, and a rotation angular velocity of 0 to 5 rad / s, preferably 0 to 3 rad / s.

[0015] In a specific embodiment of the present invention, the melt extrusion speed is 0.5~3kg / h.

[0016] In a specific embodiment of the present invention, the screw speed in the melt extrusion process is 20-50 rpm.

[0017] In a specific embodiment of the present invention, the linear speed of the 3D printing stack is 40-100 mm / s.

[0018] In a specific embodiment of the present invention, when the foaming agent is a solid foaming agent, the polymer particles containing the foaming agent are prepared by melt-extruding and granulating the polymer particles and the foaming agent together; when the foaming agent is a fluid foaming agent, the polymer particles containing the foaming agent are prepared by immersing the polymer particles in the foaming agent. It should be noted that when the foaming agent is a solid foaming agent and the particle size of the solid foaming agent is too small, a low melting point resin can be added to blend with the foaming agent for extrusion granulation. If the particle size of the solid foaming agent is too small, it is not conducive to subsequent foaming processing.

[0019] Preferably, the polymer particles are obtained by blending and extruding fibers and polymers, wherein the fiber content is 1-30wt%. More specifically, the polymer particles and the foaming agent are co-melted and extruded using a twin-screw extruder. Preferably, the fiber content in the polymer particles is 5-20wt%.

[0020] The fibers in the polymer particles will be lost after the polymer particles are subsequently blended with the foaming agent. Therefore, the fiber content in the polymer particles needs to be controlled to 5~20wt% to ensure that the fiber content in the polymer particles containing the foaming agent is 0.1~10 wt%.

[0021] In a specific embodiment of the present invention, the polymer particles containing a foaming agent are in the shape of a circle, an ellipse, or a cylinder, the average diameter of the particles is 0.5 to 5.0 mm, the diameter fluctuation range is 0.5 to 1 mm, and the hardness range of the particles is Shore A10 to Shore D85.

[0022] Preferably, the polymer particles containing the foaming agent are melt-extruded to obtain a foamed filament melt, and the diameter of the foamed filament melt is 0.6-1.5 mm. In a specific embodiment of the present invention, the diameter of the foamed filament melt is controlled to be 0.6-1.5 mm by controlling the diameter of the extrusion die to be 0.8-2.0 mm.

[0023] Preferably, the diameter of the fibers in the polymer particles containing a foaming agent is 0.1 to 10 μm.

[0024] More preferably, the aspect ratio of the fibers in the polymer particles containing a foaming agent is 5-20.

[0025] Preferably, the fiber content in the polymer particles containing a foaming agent is 0.5 to 5 wt %.

[0026] More preferably, the fiber content in the polymer particles containing a foaming agent is 0.5 to 2 wt%.

[0027] More preferably, the content of the blowing agent in the polymer particles containing the blowing agent is 0.1-10 wt %.

[0028] More preferably, the content of the blowing agent in the polymer particles containing the blowing agent is 0.5-8%.

[0029] Preferably, the polymer particles containing a foaming agent include the following components calculated in parts by mass:

[0030] 80-100 parts of polymer, 0.5-8 parts of foaming agent, 0.8-6 parts of fiber, 0-10 parts of nucleating agent, and 0-0.5 parts of antioxidant.

[0031] More preferably, the polymer includes at least one of a crystalline polymer, an amorphous polymer, a semi-crystalline plastic, and a thermoplastic elastomer.

[0032] More preferably, the amorphous polymer comprises PS.

[0033] More preferably, the semi-crystalline plastic comprises PEEK.

[0034] More preferably, the crystalline polymer comprises PE.

[0035] More preferably, the thermoplastic elastomer comprises TPU.

[0036] More preferably, the foaming agent includes at least one of a solid foaming agent and a fluid foaming agent.

[0037] More preferably, the fluid foaming agent includes at least one of CO2, N2, alkanes, and hydrogenated chlorofluorocarbon foaming agents.

[0038] More preferably, the solid foaming agent includes at least one of expandable microspheres, carbonates, azodicarbonamide, and N,N-dinitrosopentamethylenetetramine.

[0039] More preferably, the fiber includes at least one of organic fiber and inorganic fiber.

[0040] More preferably, the organic fiber includes at least one of aramid fiber, polyimide fiber, nanocellulose fiber, and PTFE fiber.

[0041] More preferably, the organic fibers include PTFE fibers.

[0042] PTFE fiber can be in-situ fiberized to form a fiber network, and its reinforcement effect is slightly better than other organic fibers such as aramid fiber.

[0043] More preferably, the inorganic fiber includes at least one of glass fiber and basalt fiber.

[0044] In a specific embodiment of the present invention, when the reinforcing capacity of the fiber is insufficient, the fiber may be subjected to a modification treatment, wherein the modification treatment is performed using a silane coupling agent.

[0045] More preferably, the nucleating agent includes at least one of calcium carbonate, talc, mica, montmorillonite, nano-silicon dioxide, carbon black, and carbon nanotubes. The main principle of the nucleating agent is heterogeneous nucleation, so solid and small-sized materials are usually selected as nucleating agents.

[0046] More preferably, the antioxidant includes at least one of an amine antioxidant and a phosphorus antioxidant.

[0047] More preferably, the particle size of the nucleating agent is 0.2-3 μm.

[0048] In a specific embodiment of the present invention, the fiber-reinforced polymer 3D printed foamed part has a tensile breaking strength increased by 100-400% compared to a fiber-free polymer 3D printed foamed part.

[0049] The present invention also protects a foamed shoe material, including the above-mentioned fiber-reinforced polymer 3D printed foamed product.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] The fiber-reinforced polymer 3D printed foamed parts prepared by the present invention are lightweight and have a density of ≤0.85g / cm 3 , and the dimensional accuracy is high, the error is as low as less than 3%, and the tensile strength is as high as 40N or more. Compared with the foamed parts without fiber reinforcement, the tensile strength is increased by more than 100%. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic diagram of the structure of the fiber reinforced polymer 3D printed foamed part in the present invention. DETAILED DESCRIPTION

[0053] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents. Among them, the raw material information used in each embodiment and comparative example is as follows (the part involving hardness refers to Shore hardness):

[0054] polymer:

[0055] A1: polystyrene PS, brand GPPS158K, BASF-Yangzi;

[0056] A2: Polyetheretherketone PEEK, brand 1000, Mitsubishi Chemical;

[0057] A3: Thermoplastic polyurethane TPU, hardness 60A, BASF, Germany.

[0058] Foaming agent:

[0059] B1: foamed microspheres, commercially available;

[0060] B2: CO2 fluid, commercially available.

[0061] Nucleating agent:

[0062] C1: calcium carbonate, average particle size 1 μm, commercially available;

[0063] C2: talc powder, average particle size 1 μm, commercially available.

[0064] fiber:

[0065] D1: PTFE fiber, commercially available, aspect ratio and diameter can be customized;

[0066] D2: Aramid fiber, commercially available, aspect ratio and diameter can be customized.

[0067] Antioxidants:

[0068] Hindered phenolic antioxidant, commercially available.

[0069] Examples 1 to 12 and Comparative Example 1

[0070] This embodiment and comparative example provide a series of fiber-reinforced polymer 3D printed foamed parts with different raw materials or process parameters, and the preparation process includes the following steps:

[0071] The polymer particles containing the foaming agent are put into the feeding unit of the 3D printing device whose wire extrusion unit is an extruder, and melt-extruded through a single screw extruder, and then the extruded foamed wire is 3D printed and stacked on a stacking platform under the action of a printer motion bracket, so as to obtain a fiber-reinforced polymer 3D printed foamed part; the polymer particles containing the foaming agent are melt-extruded to obtain a foamed wire melt, the diameter of the foamed wire melt is 0.8 mm (the diameter of the extrusion die is 1.0 mm), the screw speed during the extrusion process is 25 rpm, the extrusion speed is 0.6 kg / h, and the linear speed of the 3D printing stack is 80 mm / s;

[0072] The 3D printing device includes: a feeding unit, a micro extrusion unit, a printer motion bracket, a stacking platform, and a printer housing; the chamber temperature of the 3D printing device is 70°C, and the temperature control accuracy is 3°C; the residence time of the polymer particles containing the foaming agent in the second heating section and the third heating section is 0.5s; the temperature control accuracy of the single-screw extruder is 2°C; the rotation angle of the 3D printing stack is 10°, and the rotation angular velocity is 2 rad / s;

[0073] The single screw extruder comprises a first heating section, a second heating section and a third heating section in sequence, wherein the temperature of the first heating section is x°C, the temperature of the second heating section is y°C, and the temperature of the third heating section is z°C, wherein the real-time temperature z>y;

[0074] The polymer particles containing a foaming agent are prepared by melt-extruding the polymer particles and the foaming agent together to form granules or immersing the polymer particles in the foaming agent. The polymer particles are obtained by compounding fibers and polymers through blending and extrusion, wherein the fiber content is 1-30wt%.

[0075] The fiber-reinforced polymer 3D printed foamed parts prepared in the examples and comparative examples have structures such as Figure 1 As shown, the model size is 150×150×1.2 mm, the filling method is "X" type, and the filling density is 30%.

[0076] The specific raw materials and process parameters in Examples 1 to 12 and Comparative Example 1 are shown in Table 1 below:

[0077] Table 1. Specific raw materials and process parameters in Examples 1 to 12 and Comparative Example 1

[0078]

[0079] Comparative Example 2

[0080] A polymer 3D printed foamed part, which is different from Example 5 only in that:

[0081] The fiber content in the polymer particles containing the foaming agent was 0%.

[0082] The preparation process of the parts in this comparative example is consistent with that in Example 5.

[0083] Comparative Example 3

[0084] A fiber-reinforced polymer 3D printed foamed part, which is different from Example 5 only in that:

[0085] The fiber content in the polymer particles containing the foaming agent is 20%.

[0086] The preparation process of the parts in this comparative example is consistent with that in Example 5.

[0087] Comparative Example 4

[0088] A fiber-reinforced polymer 3D printed foamed part, which is different from Example 5 only in that:

[0089] The fiber aspect ratio is 30.

[0090] The preparation process of the parts in this comparative example is consistent with that in Example 5.

[0091] Comparative Example 5

[0092] A fiber-reinforced polymer 3D printed foamed part, which is different from Example 5 only in that:

[0093] The diameter of the fiber is 30 μm.

[0094] The preparation process of the parts in this comparative example is consistent with that in Example 5.

[0095] Comparative Example 6

[0096] A fiber-reinforced polymer 3D printed foamed part, which is different from Example 5 only in that:

[0097] The diameter of the fiber is 0.02 μm.

[0098] The preparation process of the parts in this comparative example is consistent with that in Example 5.

[0099] Comparative Example 7

[0100] A fiber-reinforced polymer 3D printed foamed part, which is different from Example 5 only in that:

[0101] The aspect ratio of the fiber is 2.

[0102] The preparation process of the parts in this comparative example is consistent with that in Example 5.

[0103] Performance Testing

[0104] Dimension error test: It is calculated by the deviation between the actual size of the product and the model size. Specifically, the dimension error φ = (V 制 -V 模 ) / V 模 , where volume V = length × width × height.

[0105] Part density test: Use a density balance to characterize the density of the part.

[0106] Tensile breaking strength test: A universal material testing machine is used to characterize the tensile breaking strength of foamed parts according to ISO17706:2003 EN standard.

[0107] Part appearance test: obtained through visual observation of the part.

[0108] Processing behavior test: obtained through visual observation during the preparation process.

[0109] The specific performance test data is shown in Table 2 below:

[0110] Table 2. Processing behavior and other properties of the parts obtained in the examples and comparative examples

[0111]

[0112]

[0113]

[0114]

[0115] As can be seen from Table 2 above, the fiber-reinforced polymer 3D printed foamed parts prepared by the present invention are lightweight and have a density of ≤0.85 g / cm 3 , and the dimensional accuracy is high, the error is as low as less than 3%, and the tensile strength is as high as 40N or more. Compared with the parts without fiber reinforcement (Comparative Example 2), the tensile strength is increased by more than 100%. According to the data of Examples 5 to 9 in Table 2, when the fiber diameter is preferably 0.1 to 10 μm and the aspect ratio is preferably 5 to 20 (Examples 8 and 9), there is better compatibility between the fiber and the foaming melt, so the performance of the obtained parts is better and the tensile strength is higher. According to the data of Examples 5, 10 to 11 in Table 2, if the amount of fiber added is too high or too low, the performance of the parts will be reduced. According to the data of Examples 5 and 12, the use of PTFE fiber for reinforcement has a better reinforcement effect than aramid fiber (Example 5), which is why PTFE fiber can be fiberized in situ.

[0116] According to the data of Comparative Example 1, it can be seen that when the conventional extrusion process is used for extrusion, the temperature of the feed section is usually as high as 100°C or above, which will lead to excessive escape of the foaming agent during the extrusion process, and the density of the obtained product is too high, which is not suitable for application in the field of shoe materials. According to the data of Comparative Examples 2 to 7, it can be seen that when no fiber is added to the system, or the amount of fiber added, the size characteristics, etc. do not meet the requirements, it is difficult to achieve the reinforcement of the product, especially when the amount of fiber added is too high (Comparative Example 3), the tensile breaking strength of the obtained product is even worse than that of the product without fiber added for reinforcement (Comparative Example 2), indicating that the amount of fiber added should not be too high.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A fiber-reinforced polymer 3D printed foamed part, characterized in that: The polymer particles containing a foaming agent are used as a preparation raw material, and are prepared by melt extrusion and foaming melt 3D printing stacking in sequence. The polymer particles containing a foaming agent also contain fibers. The content of the fibers in the polymer particles containing a foaming agent is 0.5-5wt%, the diameter is 0.1-10μm, and the aspect ratio is 5-20. The melt extrusion is performed by a single screw extruder, which sequentially comprises a first heating section, a second heating section, and a third heating section, wherein the temperature of the first heating section is 0-30°C, the temperature of the second heating section is 160-320°C, and the temperature of the third heating section is 230-390°C, wherein the real-time temperature of the third heating section is higher than the temperature of the second heating section; The polymer particles containing the foaming agent are melt-extruded to obtain a foamed wire melt, wherein the diameter of the foamed wire melt is 0.6-1.5 mm; The content of the foaming agent in the polymer particles containing the foaming agent is 0.1-10 wt %.

2. The fiber-reinforced polymer 3D printed foamed part according to claim 1, characterized in that: The polymer particles containing a foaming agent include the following components calculated by mass: 80-100 parts of polymer, 0.5-8 parts of foaming agent, 0.8-6 parts of fiber, 0-10 parts of nucleating agent, and 0-0.5 parts of antioxidant.

3. The fiber-reinforced polymer 3D printed foamed part according to claim 2, characterized in that: Include at least one of the following (a) to (f): (a) the polymer comprises at least one of a crystalline polymer, an amorphous polymer, a semi-crystalline plastic, and a thermoplastic elastomer; (b) the foaming agent comprises at least one of a solid foaming agent and a fluid foaming agent; (c) the fiber comprises at least one of organic fiber and inorganic fiber; (d) the nucleating agent comprises at least one of calcium carbonate, talc, mica, montmorillonite, nano-silica, carbon black, and carbon nanotubes; (e) the antioxidant comprises at least one of an amine antioxidant and a phosphorus antioxidant; (f) The particle size of the nucleating agent is 0.2-3 μm.

4. The fiber-reinforced polymer 3D printed foamed part according to claim 3, characterized in that: Include at least one of the following (g) to (n): (g) the amorphous polymer comprises PS; (h) the semi-crystalline plastic comprises PEEK; (i) the crystalline polymer comprises PE; (j) the thermoplastic elastomer comprises TPU; (k) the fluid foaming agent comprises at least one of CO2, N2, alkanes, and hydrogenated chlorofluorocarbon foaming agents; (l) the solid foaming agent comprises at least one of expandable microspheres, carbonates, azodicarbonamide, and N,N-dinitrosopentamethylenetetramine; (m) the organic fiber comprises at least one of aramid fiber, polyimide fiber, nanocellulose fiber, and PTFE fiber; (n) The inorganic fiber includes at least one of glass fiber and basalt fiber.

5. A foamed shoe material, characterized in that: Including the fiber reinforced polymer 3D printed foamed part as described in any one of claims 1 to 4.

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