3D printing foamed article and preparation method and application thereof

Abstract

The application provides a 3D printing foaming product and a preparation method and application thereof, and belongs to the technical field of 3D printing. The method for preparing the 3D printing foaming product provided by the application uses polyamide powder as raw material, prepares a 3D printing product, then performs supercritical fluid kettle pressure foaming on the 3D printing product, and obtains the 3D printing foaming product; by controlling the melting point and average particle size of the polyamide powder, the printing temperature, and the solubility of the supercritical fluid in the 3D printing foaming product, the 3D printing foaming product with high rebound performance, bending resistance and hydrolysis resistance is obtained, and has a wide application prospect in the field of foaming shoe materials.

Description

Technical Field

[0001] This invention relates to the field of 3D printing technology, specifically to a 3D printed foamed part, its preparation method, and its application. Background Technology

[0002] Footwear foam materials include rubber foam materials, PU foam materials, EVA foam materials, etc. The preparation process of these materials involves the decomposition of chemical foaming agents and the cross-linking of molecular chain networks. The resulting foam materials have problems such as high density, poor elasticity, and difficulty in melting and recycling due to molecular chain cross-linking. Therefore, they are increasingly unable to meet the development requirements of foam materials for sports shoes.

[0003] Elastomer foam materials, including bead-based and preform-based foam materials, are prepared using supercritical physical foaming technology from thermoplastic elastomers. These materials offer advantages such as ultra-low density, high resilience, low compression set, environmentally friendly processing, and the ability to melt and recycle the foamed products. Therefore, they are currently important raw materials for producing foamed shoe materials. The molding methods for preparing foamed shoe materials from elastomeric foam materials include PU injection molding, compression molding, and steam molding. All of these molding processes require molds to construct the curved surface structure and textured patterns of the shoe material. Using molds for processing and molding not only prolongs the manufacturing process but also incurs significant processing costs.

[0004] 3D printing technology enables moldless molding and allows for free structural design, making it an important processing method for polymer materials. Current reports indicate that 3D printing technology has been applied to the manufacture of footwear materials and has garnered widespread attention. However, current 3D-printed footwear parts are all solid structures. While offering diverse structural designs, their high true density and heavy weight limit their widespread application. To reduce the density and weight of 3D-printed footwear parts, foaming the material after 3D printing is a feasible method. However, foaming after the 3D-printed part is performed incorrectly. Because the dimensions of the pores in the 3D-printed part are often sub-millimeter level, and the size and distribution of these pores are uneven, foaming may fail or occur unevenly, leading to a decrease in the footwear material's resilience, flexural strength, and hydrolysis resistance. Summary of the Invention

[0005] The purpose of this disclosure is to overcome the shortcomings of the prior art and to provide a 3D printed foam part, its preparation method and application.

[0006] To achieve the above objectives, the technical solution adopted in this disclosure is as follows: Firstly, a method for 3D printing foamed parts is provided, comprising the following steps:

[0007] (1) Place polyamide powder with a melting point of 145-160℃ and an average particle size of 30-60μm into a 3D printer, and perform 3D printing according to the planned path. The printing temperature is 110-120℃ to obtain 3D printed parts.

[0008] (2) The 3D printed part material obtained in step (1) is impregnated with supercritical fluid to obtain impregnated 3D printed part, and then foamed to obtain 3D printed foamed part;

[0009] In step (2), the solubility of the supercritical fluid in the 3D printed foam part is 0.2-2%.

[0010] In some embodiments, the polyamide powder is PEBA powder.

[0011] In some embodiments, the lattice structure of the 3D printed planning path includes at least one of the following: circular structure, triangular structure, pentagonal structure, mesh structure, tetrahedral structure, linear structure, internal hexagonal structure, cubic structure, cubic partitioned structure, octagonal structure, concentric circle structure, serrated structure, intersecting structure, intersecting 3D structure, spiral icosahedral structure, lightning-shaped structure, and reinforced border; the mesh structure includes at least one of in-plane mesh structure and interlayer mesh structure.

[0012] In some embodiments, the lattice structure is spaced 0.2-2.0 mm apart.

[0013] In some implementations, the 3D printing conditions in step (1) are: laser power of 42-47W, powder cylinder temperature of 65-70℃, powder layer thickness of 0.09-0.15mm, and spot compensation of 0.4-0.6mm.

[0014] In some embodiments, the temperature of supercritical fluid impregnation in step (2) is 100-270°C, the pressure is 10-65 MPa, and the time is 0.5-5 h.

[0015] In some embodiments, in step (2) supercritical fluid impregnation, the supercritical fluid is at least one of carbon dioxide fluid and nitrogen fluid.

[0016] Secondly, a 3D printed foam part is provided, which is prepared by the method of the 3D printed foam part.

[0017] Thirdly, the application of the aforementioned 3D printed foamed parts in the preparation of foamed shoe materials is provided.

[0018] Fourthly, a foamed shoe material is provided, including the aforementioned 3D printed foamed part.

[0019] Compared with the prior art, the beneficial effects of this disclosure are as follows: The method for 3D printing foamed parts provided in this application uses polyamide powder as raw material to prepare 3D printed parts, and then subjectes the 3D printed parts to supercritical fluid autoclaving foaming to obtain 3D printed foamed parts; by controlling the melting point and average particle size of polyamide powder, printing temperature, and solubility of supercritical fluid in 3D printed foamed parts, 3D printed foamed parts with high resilience, bending resistance and hydrolysis resistance are obtained, which have broad application prospects in the field of foamed shoe materials. Attached Figure Description

[0020] Figure 1 This is a model diagram of a 3D printed part according to an embodiment of the present invention;

[0021] Figure 2 This is a model diagram of a 3D printed part according to an embodiment of the present invention;

[0022] Figure 3 This is a physical image of the 3D printed part obtained in Embodiment 1 of the present invention. Detailed Implementation

[0023] To facilitate understanding of this disclosure, a more complete description will be provided below. However, this disclosure may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure.

[0024] As used in this article:

[0025] "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0026] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0027] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1-5” is disclosed, the described range should be interpreted as including ranges “1-4”, “1-3”, “1-2”, “1-2 and 4-5”, “1-3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0028] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0029] "Parts by mass" refers to the basic unit of measurement that expresses the mass ratio of multiple components. One part can represent any unit mass, such as 1g or 2.689g. If we say that component A has 'a' parts by mass and component B has 'b' parts by mass, it means that the mass ratio of component A to component B is a:b. It is important to understand that, unlike mass percentage content, the sum of the mass parts of all components is not limited to 100 parts.

[0030] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0031] In one aspect, a method for 3D printing foamed parts is provided, comprising the following steps:

[0032] (1) Place polyamide powder with a melting point of 145-160℃ and an average particle size of 30-60μm into a 3D printer, and perform 3D printing according to the planned path. The printing temperature is 110-120℃ to obtain 3D printed parts.

[0033] (2) The 3D printed part obtained in step (1) is impregnated with supercritical fluid to obtain an impregnated 3D printed part, and then foamed to obtain a foamed 3D printed part;

[0034] In step (2), the solubility of the supercritical fluid in the 3D printed foam part is 0.2-2%.

[0035] Specifically, the 3D printing technology in this application is laser selective sintering technology. This technology uses the principle of CO2 laser irradiation to sinter powder layers. Under computer control, the powder is selectively sintered according to the outline shape of the sintered part, and the powder is layered and stacked to form the part. The powder in the unsintered area serves as a support layer to support the sintered part without the need for additional support.

[0036] The method for 3D printing foamed parts provided in this application uses polyamide powder as raw material to prepare 3D printed parts, and then subjectes the 3D printed parts to supercritical fluid autoclaving foaming to obtain 3D printed foamed parts. By controlling the melting point and average particle size of polyamide powder, printing temperature, and the solubility of supercritical fluid in the 3D printed foamed parts, 3D printed foamed parts with high resilience, bending resistance, and hydrolysis resistance are obtained, which have broad application prospects in the field of foamed footwear materials.

[0037] Specifically, the reason for controlling the above parameters in the preparation method provided in this application is that the melting point and average particle size of the polyamide powder, the printing temperature, and the solubility of the supercritical fluid and the impregnation temperature during the foaming process all affect the resilience, bending resistance, and hydrolysis resistance of the 3D printed foamed parts. If the melting point of the polyamide powder is too low, it will melt more easily during the 3D printing process, which may lead to insufficient bonding between the polyamide powder particles, forming pores or defects, resulting in a decrease in the density of the 3D printed foamed parts, thereby reducing their resilience, bending resistance, and hydrolysis resistance. If the melting point of the polyamide powder is too high, some of the polyamide powder will not melt completely during the 3D printing process, resulting in particulate powder in the 3D printed foamed parts, which will reduce the bonding strength between the polyamide powder layers, forming pores or defects, thus reducing the density of the 3D printed foamed parts, thereby reducing their resilience, bending resistance, and hydrolysis resistance.

[0038] When the average particle size of polyamide powder is less than 30μm, the electrostatic interaction between the polyamide powder particles is large, which leads to the inability to spread the powder properly. When the average particle size of polyamide powder is greater than 60μm, the sintering fusion will be reduced during the 3D printing process, resulting in a decrease in the resilience of the 3D printed foamed parts. At the same time, it will also result in many large polyamide powder particles on the surface of the 3D printed foamed parts, making the surface of the 3D printed foamed parts rough and reducing the printing accuracy of the 3D printed foamed parts.

[0039] During the 3D printing process, printing temperatures below 110℃ will result in micropores in the 3D printed foamed parts, which will reduce the resilience, bending resistance, and hydrolysis resistance of the 3D printed foamed parts; printing temperatures above 120℃ will cause polyamide degradation, which will also reduce the resilience, bending resistance, and hydrolysis resistance of the 3D printed foamed parts.

[0040] During the foaming process, supercritical fluid rapidly diffuses into the 3D printed part at high temperature. Through physical foaming, the 3D printed part undergoes cell nucleation and growth, resulting in a foamed 3D printed part. If the solubility of supercritical fluid in the foamed 3D printed part is less than 0.2%, it will result in a low expansion ratio. If the solubility of supercritical fluid in the foamed 3D printed part is greater than 2%, it will cause the foamed 3D printed part to twist, deform, or melt.

[0041] As a foaming method, foaming can be carried out by depressurization foaming or heating foaming; it can also be carried out by introducing a heat medium, which can be air or hot water steam.

[0042] Specifically, the depressurization rate of the depressurization foam is 50-100 MPa / s, for example, but not limited to 50 MPa / s, 60 MPa / s, 70 MPa / s, 80 MPa / s, 90 MPa / s, and 100 MPa / s.

[0043] Specifically, the melting point of the polyamide powder can be, but is not limited to, 145℃, 146℃, 147℃, 148℃, 149℃, 150℃, 151℃, 152℃, 153℃, 154℃, 155℃, 156℃, 157℃, 158℃, 159℃, or 160℃; the testing method is differential scanning calorimetry, according to the national standard GB / T 19466.3-2004. In this application, the melting point of the polyamide powder refers to the peak melting temperature in GB / T 19466.3-2004.

[0044] Specifically, the average particle size of the polyamide powder can be, but is not limited to, 30μm, 32μm, 35μm, 37μm, 40μm, 43μm, 45μm, 48μm, 50μm, 53μm, 55μm, 58μm, or 60μm, preferably 40-50μm; the testing method is laser diffraction, according to the national standard GB / T 19077-2016.

[0045] The method for controlling the average particle size of polyamide powder in this disclosure is not limited. For example, the average particle size of polyamide powder can be controlled by crushing, grinding, or sieving. If the average particle size of polyamide powder is not within the range of this disclosure after a single crushing or grinding, multiple crushing or grinding can be performed until the average particle size of polyamide powder reaches the required range. In addition, the average particle size of polyamide powder can also reach the required range by extending the crushing or grinding time during the crushing or grinding process.

[0046] Specifically, the steps for grinding polyamide powder are as follows:

[0047] Polyamide powder is added to a container filled with liquid nitrogen and left to stand for 5-10 minutes. Then it is transferred to a grinding mill for grinding. The resulting material is sieved to obtain the first powder with an average particle size of 270-830 μm.

[0048] Add the first powder to a container filled with liquid nitrogen, let it stand for 5-10 minutes, and then transfer it to a grinder to grind it to the required average particle size.

[0049] Specifically, the printing temperature of the 3D printing can be, but is not limited to, 110℃, 111℃, 112℃, 113℃, 114℃, 115℃, 116℃, 117℃, 118℃, 119℃, or 120℃; preferably, the temperature control accuracy of the 3D printing temperature is 0.5-5℃, and more preferably 1-3℃.

[0050] Specifically, the solubility of the supercritical fluid in the impregnated 3D printed part can be, but is not limited to, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, or 2.0%.

[0051] In this application, the solubility of the supercritical fluid in the 3D printed foam part can be controlled by adjusting the impregnation pressure and temperature. The solubility (%) of the supercritical fluid in the 3D printed foam part is (m2-m1)×100% / m1, where m1 is the mass of the 3D printed part and m2 is the mass of the 3D printed foam part.

[0052] In some embodiments, the polyamide powder is PEBA powder. Using the above-mentioned types of polyamide powder as raw materials for 3D printed foamed parts can further improve the resilience, bending resistance, and hydrolysis resistance of 3D printed foamed parts.

[0053] In this application, PEBA refers to polyether amide block copolymer.

[0054] In some embodiments, the lattice structure of the 3D printed planning path includes at least one of the following: circular structure, triangular structure, pentagonal structure, mesh structure, tetrahedral structure, linear structure, internal hexagonal structure, cubic structure, cubic partitioned structure, octagonal structure, concentric circle structure, serrated structure, intersecting structure, intersecting 3D structure, spiral icosahedral structure, lightning-shaped structure, and reinforced border; the mesh structure includes at least one of in-plane mesh structure and interlayer mesh structure.

[0055] In this application, a lattice structure refers to a three-dimensional set of repeating or non-repeating connection nodes.

[0056] In this application, the lattice units of each layer in the 3D printed foam part are amorphously dispersed, that is, the size or spacing of the lattice units can increase or decrease with a single gradient, or increase or decrease with a double gradient, or increase or decrease in a Gaussian distribution.

[0057] In this application, the planning path for 3D printing refers to using computer 3D modeling software to draw the structure of the 3D printed part and using the model to generate a printing control program.

[0058] In some embodiments, the lattice structure is spaced 0.2-2.0 mm, for example, but not limited to 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, and 2.0 mm.

[0059] In this application, such as Figure 1 As shown, the spacing of the crystal lattice structure refers to the distance between the support rods inside the crystal lattice unit.

[0060] In this application, when subjected to external force, the 3D printed foam part will deform. When the lattice structure spacing is 0.2-2.0mm, the lattice structure in the 3D printed foam part is densely distributed, and the lattice structure can provide better support and stability, making the deformation of the 3D printed foam part easier to recover and improving the resilience of the 3D printed foam part.

[0061] In some implementations, the 3D printing conditions in step (1) are: laser power of 42-47W, powder feeding cylinder temperature of 65-70℃, powder layer thickness of 0.09-0.15mm, and spot compensation of 0.4-0.6mm.

[0062] Specifically, the laser power can be, but is not limited to, 42W, 43W, 44W, 45W, 46W, and 47W. Within the above laser power range, the gaps and viscosity between polyamide powders can be reduced, the density of polyamide powders can be increased, and the mechanical properties, resilience, bending resistance, and hydrolysis resistance of 3D printed foamed parts can be improved.

[0063] Specifically, the temperature of the powder feeding cylinder can be, but is not limited to, 65℃, 65.5℃, 66℃, 66.5℃, 67℃, 67.5℃, 68℃, 68.5℃, 69℃, 69.5℃, and 70℃. Within the above range, the temperature difference between the powder irradiated by the laser and the powder not irradiated can be reduced, thereby reducing the deformation of 3D printed foamed parts, improving the mechanical properties and resilience of 3D printed foamed parts, and accelerating the sintering rate while reducing energy consumption.

[0064] Specifically, the thickness of the powder layer can be, but is not limited to, 0.09 mm, 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, or 0.15 mm; a powder layer thickness within the above range is beneficial for improving the mechanical properties, resilience, and bending resistance of 3D printed foamed parts.

[0065] Specifically, the spot compensation can be, but is not limited to, 0.4 mm, 0.42 mm, 0.45 mm, 0.47 mm, 0.5 mm, 0.53 mm, 0.55 mm, 0.58 mm, or 0.6 mm.

[0066] In this application, before the supercritical fluid impregnation after the 3D printed part is printed, a cooling and cleaning step is also performed sequentially.

[0067] Specifically, the cooling step is as follows: place the 3D printed part in an environment of 20-30℃ for 3-5 hours to lower the temperature of the 3D printed part and ensure that the 3D printed part is not easily deformed.

[0068] Specifically, the cleaning steps are as follows: use cleaning tools to clean the surface of the 3D printed part and the interior of the hollow structure to remove residual polyamide powder, so as to avoid the powder affecting the overall performance of the 3D printed foamed part during the supercritical fluid impregnation process.

[0069] This application does not impose specific restrictions on cleaning tools, as long as they can remove residual polyamide powder from the surface of the 3D printed part and the interior of the hollow structure, such as wire, brush, air gun, etc.

[0070] In some embodiments, the temperature of supercritical fluid impregnation in step (2) is 100-270°C, the pressure is 10-65 MPa, and the time is 0.5-5 h.

[0071] Specifically, the immersion temperature can be, but is not limited to, 100°C, 130°C, 150°C, 170°C, 190°C, 210°C, 230°C, 250°C, or 270°C.

[0072] Specifically, the impregnation pressure can be, but is not limited to, 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, 45 MPa, 50 MPa, 55 MPa, 60 MPa, and 65 MPa.

[0073] Specifically, the soaking time can be, but is not limited to, 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, or 5h.

[0074] When the temperature, pressure, and time of immersion are within the above range, it is beneficial for the foaming of 3D printed parts to obtain 3D printed foamed parts with high resilience, bending resistance, and hydrolysis resistance.

[0075] In some embodiments, in step (2) supercritical fluid impregnation, the supercritical fluid is at least one of carbon dioxide fluid and nitrogen fluid.

[0076] Secondly, a 3D printed foam part is provided, which is prepared by the method of the 3D printed foam part.

[0077] In a specific embodiment of the present invention, the above-mentioned 3D printed foamed parts can be at least one of foamed shoe upper parts, foamed shoe insole parts, foamed insole parts, and foamed midsole parts.

[0078] Thirdly, the application of the aforementioned 3D printed foamed parts in the preparation of foamed shoe materials is provided.

[0079] Fourthly, a foamed shoe material is provided, including the aforementioned 3D printed foamed part.

[0080] Foamed footwear materials are subjected to repeated stretching, bending, and compression during long-term service. Simultaneously, the structural stability, comfort, and elasticity of these materials significantly impact the wearer's athletic performance. Therefore, footwear applications place high demands on the resilience, bending resistance, and hydrolysis resistance of 3D-printed foamed components. The 3D-printed foamed components provided by this invention exhibit high resilience, bending resistance, and hydrolysis resistance; thus, they have broad application prospects in the field of foamed footwear materials.

[0081] The raw materials used in the embodiments and comparative examples are described below, but are not limited to these materials:

[0082] Polyamide powder A: PEBA, melting point 154℃, average particle size 45.5μm, TPA4006P, Evonik;

[0083] Polyamide powder B: PEBA, melting point 147℃, average particle size 45.2μm, PEBAX® 4533SP 01, Arkema;

[0084] Polyamide powder C: PEBA, melting point 160℃, average particle size 45.3μm, PEBAX® 4033SP 01, Arkema;

[0085] Polyamide powder D: PEBA, melting point 147℃, average particle size 40.2μm, PEBAX® 4533SP 01, Arkema;

[0086] Polyamide powder E: PEBA, melting point 147℃, average particle size 49.9μm, PEBAX®4533SP 01, Arkema;

[0087] Polyamide powder F: PEBA, melting point 147℃, average particle size 30.1μm, PEBAX®4533SP 01, Arkema;

[0088] Polyamide powder G: PEBA, melting point 147℃, average particle size 59.8μm, PEBAX® 4533SP 01, Arkema;

[0089] Polyamide powder H: PEBA, melting point 169℃, average particle size 44.9μm, PEBAX® 6333SP 01, Arkema;

[0090] Polyamide powder I: PEBA, melting point 135℃, average particle size 45μm, Pebax Invent 35, Arkema;

[0091] Polyamide powder J: PEBA, melting point 147℃, average particle size 25.1μm, PEBAX® 4533SP 01, Arkema;

[0092] Polyamide powder K: PEBA, melting point 147℃, average particle size 64.9μm, PEBAX® 4533SP 01, Arkema.

[0093] Example 1

[0094] This embodiment provides a method for 3D printing foamed parts, including the following steps:

[0095] like Figure 2 As shown, a 3D model of the 3D printed part was drawn using 3D software (Materialise Magics). The lattice structure of the 3D printed part is a quadrilateral structure with a lattice spacing of 0.5mm, and it was saved as a .stl file. The saved STL file was imported into the 3D printing equipment, and the position of the workpiece was adjusted and placed using (BuildStar). The slicing software that comes with the 3D printing equipment was used to slice the workpiece and save it to the desktop. The sliced ​​workpiece was imported into the printing software (MakeStar P System) to start printing. Polyamide powder A was put into the 3D printer and 3D printed according to the planned path. After printing, it was left to stand in an environment of 25℃ for 3 hours, and then the residual polyamide powder on the surface of the 3D printed part and inside the hollow structure was removed.

[0096] The 3D printing parameters are as follows: laser power is 45W, powder cylinder temperature is 68℃, powder layer thickness is 0.099mm, spot compensation is 0.5mm, and printing temperature is 115℃.

[0097] The 3D printed part material, after removing residual polyamide powder, is impregnated with nitrogen fluid. The resulting impregnated 3D printed part is then depressurized and foamed within 1 second to obtain a foamed 3D printed part. The appearance of the part is shown in the image below. Figure 3 As shown; the impregnation temperature was 150℃, the pressure was 30MPa, the time was 0.5h, and the solubility of the supercritical fluid in the 3D printed foamed part was 1.0%.

[0098] Example 2

[0099] This embodiment provides a method for 3D printing foamed parts, including the following steps:

[0100] like Figure 2 As shown, a 3D model of the 3D printed part was drawn using 3D software (Materialise Magics). The lattice structure of the 3D printed part is a quadrilateral structure with a lattice spacing of 0.5mm, and it was saved as a .stl file. The saved STL file was imported into the 3D printing equipment, and the position of the workpiece was adjusted and placed using (BuildStar). The slicing software that comes with the 3D printing equipment was used to slice the workpiece and save it to the desktop. The sliced ​​workpiece was imported into the printing software (MakeStar P System) to start printing. Polyamide powder A was put into the 3D printer and 3D printed according to the planned path. After printing, it was left to stand in an environment of 25℃ for 3 hours, and then the residual polyamide powder on the surface of the 3D printed part and inside the hollow structure was removed.

[0101] The 3D printing parameters are as follows: laser power is 42W, powder cylinder temperature is 70℃, powder layer thickness is 0.15mm, spot compensation is 0.5mm, and printing temperature is 115℃.

[0102] The 3D printed part material after removing residual polyamide powder is impregnated with nitrogen fluid. The resulting impregnated 3D printed part is depressurized and foamed within 1 second to obtain a 3D printed foamed part. The impregnation temperature is 150℃, the pressure is 10MPa, the time is 5h, and the solubility of supercritical fluid in the 3D printed foamed part is 0.5%.

[0103] Example 3

[0104] This embodiment provides a method for 3D printing foamed parts, including the following steps:

[0105] like Figure 2As shown, a 3D model of the 3D printed part was drawn using 3D software (Materialise Magics). The lattice structure of the 3D printed part is a quadrilateral structure with a lattice spacing of 0.5mm, and it was saved as a .stl file. The saved STL file was imported into the 3D printing equipment, and the position of the workpiece was adjusted and placed using (BuildStar). The slicing software that comes with the 3D printing equipment was used to slice the workpiece and save it to the desktop. The sliced ​​workpiece was imported into the printing software (MakeStarP System) to start printing. Polyamide powder A was put into the 3D printer and 3D printed according to the planned path. After printing, it was left to stand in an environment of 25℃ for 3 hours, and then the residual polyamide powder on the surface of the 3D printed part and inside the hollow structure was removed.

[0106] The 3D printing parameters are as follows: laser power is 47W, powder cylinder temperature is 65℃, powder layer thickness is 0.09mm, spot compensation is 0.5mm, and printing temperature is 115℃.

[0107] The 3D printed part material after removing residual polyamide powder is impregnated with nitrogen fluid. The impregnated 3D printed part is depressurized and foamed within 1 second to obtain a 3D printed foamed part. The impregnation temperature is 150℃, the pressure is 65MPa, the time is 0.5h, and the solubility of supercritical fluid in the 3D printed foamed part is 1.8%.

[0108] Example 4

[0109] This embodiment provides a method for 3D printing foamed parts, which differs from Embodiment 1 only in that polyamide powder B is used instead of polyamide powder A, while the remaining steps and parameters are the same as in Embodiment 1.

[0110] Example 5

[0111] This embodiment provides a method for 3D printing foamed parts, which differs from Embodiment 1 only in that polyamide powder C is used instead of polyamide powder A, while the remaining steps and parameters are the same as in Embodiment 1.

[0112] Example 6

[0113] This embodiment provides a method for 3D printing foamed parts, which differs from Embodiment 1 only in that polyamide powder D is used instead of polyamide powder A, while the remaining steps and parameters are the same as in Embodiment 1.

[0114] Example 7

[0115] This embodiment provides a method for 3D printing foamed parts, which differs from Embodiment 1 only in that polyamide powder E is used instead of polyamide powder A, while the remaining steps and parameters are the same as in Embodiment 1.

[0116] Example 8

[0117] This embodiment provides a method for 3D printing foamed parts, which differs from Embodiment 1 only in that polyamide powder F is used instead of polyamide powder A, while the remaining steps and parameters are the same as in Embodiment 1.

[0118] Example 9

[0119] This embodiment provides a method for 3D printing foamed parts, which differs from Embodiment 1 only in that polyamide powder G is used instead of polyamide powder A, while the remaining steps and parameters are the same as in Embodiment 1.

[0120] Example 10

[0121] This embodiment provides a method for 3D printing foamed parts, which differs from Embodiment 1 only in that the printing temperature of 3D printing is 110℃, while the other steps and parameters are the same as in Embodiment 1.

[0122] Example 11

[0123] This embodiment provides a method for 3D printing foamed parts, which differs from Embodiment 1 only in that the printing temperature of 3D printing is 120°C, while the other steps and parameters are the same as in Embodiment 1.

[0124] Example 12

[0125] This embodiment provides a method for 3D printing foamed parts, which differs from Embodiment 1 only in that the immersion temperature is 100°C and the solubility of the supercritical fluid in the 3D printed foamed parts is 1.3%. All other steps and parameters are the same as in Embodiment 1.

[0126] Example 13

[0127] This embodiment provides a method for 3D printing foamed parts, which differs from Embodiment 1 only in that the immersion temperature is 200°C and the solubility of the supercritical fluid in the 3D printed foamed parts is 0.8%. All other steps and parameters are the same as in Embodiment 1.

[0128] Example 14

[0129] This embodiment provides a method for 3D printing foamed parts, which differs from Embodiment 1 only in that the impregnation temperature is 270°C and the solubility of the supercritical fluid in the 3D printed foamed parts is 0.4%. All other steps and parameters are the same as in Embodiment 1.

[0130] Example 15

[0131] This embodiment provides a method for 3D printing foamed parts, which differs from Embodiment 1 only in that the lattice structure spacing of the 3D printed parts is 0.2 mm, while the other steps and parameters are the same as in Embodiment 1.

[0132] Example 16

[0133] This embodiment provides a method for 3D printing foamed parts, which differs from Embodiment 1 only in that the lattice structure spacing of the 3D printed parts is 1.5 mm, and the remaining steps and parameters are the same as in Embodiment 1.

[0134] Example 17

[0135] This embodiment provides a method for 3D printing foamed parts, which differs from Embodiment 1 only in that the lattice structure spacing of the 3D printed parts is 2.0 mm, and the other steps and parameters are the same as in Embodiment 1.

[0136] Comparative Example 1

[0137] This comparative example provides a method for 3D printing foamed parts, which differs from Example 1 only in that polyamide powder H is used instead of polyamide powder A, while the remaining steps and parameters are the same as in Example 1.

[0138] Comparative Example 2

[0139] This comparative example provides a method for 3D printing foamed parts, which differs from Example 1 only in that polyamide powder I is used instead of polyamide powder A, while the remaining steps and parameters are the same as in Example 1.

[0140] Comparative Example 3

[0141] This comparative example provides a method for 3D printing foamed parts, which differs from Example 1 only in that polyamide powder J is used instead of polyamide powder A, while the remaining steps and parameters are the same as in Example 1.

[0142] Comparative Example 4

[0143] This comparative example provides a method for 3D printing foamed parts, which differs from Example 1 only in that polyamide powder K is used instead of polyamide powder A, while the remaining steps and parameters are the same as in Example 1.

[0144] Comparative Example 5

[0145] This comparative example provides a method for 3D printing foamed parts, which differs from Example 1 only in that the printing temperature of 3D printing is 100°C, while the other steps and parameters are the same as in Example 1.

[0146] Comparative Example 6

[0147] This comparative example provides a method for 3D printing foamed parts, which differs from Example 1 only in that the printing temperature of 3D printing is 130°C, while the other steps and parameters are the same as in Example 1.

[0148] Comparative Example 7

[0149] This comparative example provides a method for 3D printing foamed parts, which differs from Example 1 only in that: the impregnation temperature is 80°C, the impregnation pressure is 70 MPa, and the solubility of the supercritical fluid in the 3D printed foamed parts is 2.5%. All other steps and parameters are the same as in Example 1.

[0150] Comparative Example 8

[0151] This comparative example provides a method for 3D printing foamed parts, which differs from Example 1 only in that the immersion temperature is 300°C and the solubility of the supercritical fluid in the 3D printed foamed parts is 0.1%. All other steps and parameters are the same as in Example 1.

[0152] Performance testing

[0153] The performance of the 3D printed foamed parts obtained in the test examples and comparative examples was tested using the following methods:

[0154] Rebound performance: Measured using a ball rebound tester; rebound rate % = (ball rebound height / initial height) × 100%.

[0155] Bending resistance: Referring to standard ISO 17707-2005, the sample to be tested is bent at 90° for 400,000 times at room temperature. The sample is then observed for cracks. No cracks: no cracks on the sample surface; slight cracks: crack length ≤ 1.0 mm; obvious cracks: crack length 1.1-3.0 mm; severe cracks: crack length > 3.0 mm.

[0156] Hydrolysis resistance: The reference standard is ISO 4611-2010. The test sample was placed in a constant temperature and humidity chamber and aged for 7 days at 60℃ and 95% humidity. The tensile strength and elongation at break of the sample before and after aging were tested according to ISO 527-1:2019, and the tensile strength retention rate and elongation at break retention rate were calculated. Tensile strength retention rate (%) = σ2 / σ1 × 100%; where σ1 is the initial tensile strength and σ2 is the tensile strength after aging. Elongation at break retention rate (%) = ε2 / ε1 × 100%; where ε1 is the initial elongation at break and ε2 is the elongation at break after aging.

[0157] The test results are shown in Table 1.

[0158] Table 1

[0159]

[0160] As shown in Table 1, the springback rate of the 3D printed foamed parts of this application is ≥60.8%; after being bent at 90° for 400,000 times at room temperature, there are almost no cracks; after aging for 7 days at a temperature of 60°C and a humidity of 95%, the tensile strength retention rate is ≥82.2% and the elongation at break retention rate is ≥72.3%.

[0161] Experimental data from Examples 1, 4-9, and Comparative Examples 1-4 show that polyamide powder with a melting point less than 145℃ or greater than 160℃ and an average particle size less than 30μm or greater than 60μm exhibits a springback rate ≤58.1% in the resulting 3D printed foamed parts. After 400,000 90° bends at room temperature, slight cracks appear. After aging for 7 days at 60℃ and 95% humidity, the tensile strength retention rate is ≤79.2%, and the elongation at break retention rate is ≤71.4%. This indicates that only polyamide powder with a melting point of 145-160℃ and an average particle size of 30-60μm can produce 3D printed foamed parts with high springback, bending resistance, and hydrolysis resistance.

[0162] Experimental data from Examples 1, 10-14, and Comparative Examples 5-8 show that when the printing temperature is below 110℃ or above 120℃, and the solubility of the supercritical fluid in the 3D printed foam part is less than 0.2% or greater than 2%, the resilience of the resulting 3D printed foam part is ≤57.2%. After 400,000 90° bends at room temperature, slight or obvious cracks appear. After aging for 7 days at 60℃ and 95% humidity, the tensile strength retention rate is ≤78.1%, and the elongation at break retention rate is ≤67.6%. Therefore, a 3D printed foam part with high resilience, bending resistance, and hydrolysis resistance can only be obtained when the printing temperature is 110-120℃ and the solubility of the supercritical fluid in the 3D printed foam part is 0.2-2%.

[0163] Experimental data from Examples 1 and 15-17 show that when the lattice structure spacing of the planned path in 3D printing is 0.5-1.5 mm, the springback rate of the obtained 3D printed foamed parts is ≥62.5%. After 400,000 90° bends at room temperature, no cracks were observed. After aging for 7 days at 60°C and 95% humidity, the tensile strength retention rate is ≥87.1%, and the elongation at break retention rate is ≥76.4%. This indicates that when the lattice structure spacing of the planned path in 3D printing is 0.5-1.5 mm, 3D printed foamed parts with high springback performance, bending resistance, and hydrolysis resistance can be obtained.

[0164] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of this disclosure and not to limit the scope of protection of this disclosure. Although this disclosure has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this disclosure without departing from the substance and scope of the technical solutions of this disclosure.

Claims

1. A method for 3D printing foamed parts, characterized in that, Includes the following steps: (1) Place PEBA powder with a melting point of 145-160℃ and an average particle size of 30-60μm into the 3D printer, and perform 3D printing according to the planned path. The printing temperature is 110-120℃ to obtain 3D printed parts. (2) The 3D printed part obtained in step (1) is impregnated with supercritical fluid to obtain an impregnated 3D printed part, and then foamed to obtain a foamed 3D printed part; In step (2), the solubility of the supercritical fluid in the 3D printed foam part is 0.2-2%.

2. The method for 3D printing foamed parts as described in claim 1, characterized in that, The lattice structure of the 3D printing planning path includes at least one of the following: circular structure, triangular structure, quadrilateral structure, pentagonal structure, mesh structure, tetrahedral structure, linear structure, internal hexagonal structure, cubic structure, octagonal structure, concentric circle structure, serrated structure, intersecting structure, spiral icosahedral structure, lightning-shaped structure, and reinforced border. The mesh structure includes at least one of the following: in-plane mesh structure and interlayer mesh structure.

3. The method for 3D printing foamed parts as described in claim 2, characterized in that, The lattice structure has a spacing of 0.2-2.0 mm.

4. The method for 3D printing foamed parts as described in claim 1, characterized in that, The conditions for 3D printing in step (1) are: laser power of 42-47W, powder feeding cylinder temperature of 65-70℃, powder layer thickness of 0.09-0.15mm, and spot compensation of 0.4-0.6mm.

5. The method for 3D printing foamed parts as described in claim 1, characterized in that, In step (2), the temperature of supercritical fluid immersion is 100-270℃, the pressure is 10-65MPa, and the time is 0.5-5h.

6. The method for 3D printing foamed parts as described in claim 1, characterized in that, In step (2), the supercritical fluid impregnation process uses at least one of carbon dioxide fluid and nitrogen fluid.

7. A 3D printed foamed part, characterized in that, It is prepared by the method of 3D printing foamed parts according to any one of claims 1-6.

8. The application of the 3D printed foamed part as described in claim 7 in the preparation of foamed shoe materials.

9. A foamed shoe material, characterized in that, Including the 3D printed foamed parts as described in claim 7.

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