A method of recycling polyester textile to produce fused deposition 3D printing wire

Abstract

The application discloses a method for producing fused deposition 3D printing wire material from recycled polyester textiles, which comprises: heat pressing and forming polyester textiles to obtain dense PET sheet; mixing epoxy tackifier after cooling the heat pressed dense PET sheet, and then crushing; extruding the powder or particles produced after crushing to produce fused deposition 3D printing wire material; the application not only overcomes the problem that waste textiles are loose and difficult to process, but also improves the extrusion processing stability of recycled PET material; the elasticity of recycled PET melt is improved, the extrusion processing stability of recycled PET material and the mechanical properties of 3D printed parts are improved; and the polyester waste textiles with low cost are used as raw materials to produce high value-added fused deposition 3D printing wire material.

Description

Technical Field

[0001] This invention relates to the fields of waste clothing processing and fused deposition modeling (FDM) 3D printing filament preparation, and particularly to a method for producing fused deposition modeling (FDM) 3D printing filament from recycled polyester textiles. Background Technology

[0002] Polyester fiber (polyester) is currently the most produced chemical fiber, with polyethylene terephthalate (PET) as its main component. Due to its high strength and corrosion resistance, polyester fiber is widely used in various textiles. Currently, the recycling rate of polyester textiles remains low both domestically and internationally. Reprocessing technology for polyester textiles is still in its early stages of research, and there is a lack of high-value-added recycling pathways, leading to its rough classification as a non-natural fiber and its frequent disposal through landfill and incineration, which significantly reduces its recycling rate and causes environmental pollution. Therefore, progress in polyester textile recycling technology and methods has been a major concern in the industry. To address this issue, a technology has been proposed to use recycled polyester textiles to produce fused deposition modeling (FDM) filaments for 3D printing. This technology involves first shredding the polyester textiles into small particles, then processing these particles into plastic filaments that can be reused in 3D printing. However, the technology for producing fused deposition modeling (FDM) filaments from recycled polyester textiles is still in the exploratory stage both domestically and internationally. This is because waste polyester textiles have low bulk density and loose structure, making it difficult to form a dense melt during physical and mechanical recycling. Furthermore, since the main component of polyester textiles is PET, which has low viscoelasticity in the molten state, it limits its application in extrusion molding to prepare 3D printing filaments. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for producing fused deposition modeling filaments from recycled polyester textiles, addressing the shortcomings of existing technologies in the recycling of polyester textiles, which make it difficult to form a dense melt and perform extrusion processing.

[0004] The technical solution adopted by this invention to solve its technical problem is: a method for producing fused deposition modeling (FDM) filaments from recycled polyester textiles, the method comprising:

[0005] Step 1: Perform hot pressing on polyester textiles to obtain dense PET sheets;

[0006] Step 2: After the dense PET sheet is cooled by hot pressing, it is mixed with an epoxy tackifier and then pulverized.

[0007] Step 3: The powder or particles produced after crushing are extruded into fused deposition 3D printing filaments to produce fused deposition 3D printing filaments.

[0008] Furthermore, in the method for producing fused deposition modeling 3D printing filaments from recycled polyester textiles according to the present invention, during hot pressing in step 1, the hot pressing temperature is 265 to 275°C, the forming pressure is 0.5 to 10 MPa, and the pressure holding time is 0.5 to 5 minutes.

[0009] Furthermore, in the method for producing fused deposition modeling 3D printing filaments from recycled polyester textiles according to the present invention, step 1 further includes: drying the polyester textiles at 50 to 60°C for 6 to 12 hours to reduce their moisture content before hot pressing the polyester textiles.

[0010] Furthermore, in the method for producing fused deposition modeling 3D printing filaments from recycled polyester textiles described in this invention, step 2 specifically includes: cooling the hot-pressed dense PET sheet to below 50°C, mixing it with an epoxy tackifier, and then pulverizing it to obtain powder or granules.

[0011] Furthermore, in the method for producing fused deposition modeling 3D printing filaments from recycled polyester textiles according to the present invention, the epoxy tackifier is a copolymer of polystyrene and its derivatives with glycidyl methacrylate and its derivatives. The epoxy tackifier has a weight-average molecular weight of 6,000 to 10,000, an epoxy equivalent of 300 to 500 g / mol, and a required reaction temperature of 170 to 330°C.

[0012] Furthermore, in the method for producing fused deposition modeling 3D printing filaments from recycled polyester textiles according to the present invention, the epoxy tackifier accounts for 0.5% to 4% of the total weight percentage of the mixed mixture.

[0013] Furthermore, in the method for producing fused deposition modeling 3D printing filaments from recycled polyester textiles according to the present invention, in step 3, during extrusion molding, the barrel temperature of the extruder is controlled within the required reaction temperature range of the epoxy tackifier.

[0014] Furthermore, in the method for producing fused deposition modeling 3D printing filaments from recycled polyester textiles according to the present invention, the feed temperature of the extruder in step 3 is 20 to 80°C, the barrel temperature is 220 to 265°C, and the die temperature is 200 to 240°C.

[0015] Furthermore, in the method for producing fused deposition modeling 3D printing filaments from recycled polyester textiles described in this invention, the extruder in step 3 is a single-screw extruder with a screw speed of 40 to 60 rpm.

[0016] The method for producing fused deposition modeling (FDM) 3D printing filaments from recycled polyester textiles of the present invention has the following beneficial effects: The use of a thermoforming process to recycle polyester textiles not only overcomes the problem of loose and difficult-to-process waste textiles but also improves the extrusion processing stability of recycled PET materials; the use of epoxy tackifiers improves the elasticity of the recycled PET melt, enhances the extrusion processing stability of the recycled PET material, and improves the mechanical properties of 3D printed parts; the present invention enables the production of high-value-added FDM 3D printing filaments using low-cost waste polyester textiles as raw materials; the present invention provides profit margins for polyester textile recycling, increases the recycling rate of polyester textiles, reduces environmental pollution caused by polyester textiles, and reduces the production cost of FDM 3D printing filaments produced from recycled polyester textiles while ensuring a certain mechanical strength. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort:

[0018] Figure 1 A flowchart illustrating the method for producing fused deposition modeling 3D printing filaments from recycled polyester textiles according to the present invention;

[0019] Figure 2 This is a schematic diagram of the melt elastic modulus G' of recycled PET material after 3D printing, provided in an embodiment of the present invention.

[0020] Figure 3 A schematic diagram of the tensile fracture surface of a 3D printed part provided in an embodiment of the present invention. Detailed Implementation

[0021] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Typical embodiments of the invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and complete. It should be understood that the embodiments of the present invention and the specific features thereof are detailed descriptions of the technical solutions of this application, and not limitations thereof. Where there is no conflict, the embodiments of the present invention and the technical features thereof can be combined with each other.

[0022] To address the shortcomings of existing technologies in recycling polyester textiles, such as the difficulty in forming a dense melt and the challenge in extrusion processing, this invention proposes a method for producing fused deposition modeling (FDM) 3D printing filaments from recycled polyester textiles. (Refer to...) Figure 1 The method of the present invention includes:

[0023] S101: Polyester textiles are subjected to thermoforming to obtain dense PET sheets.

[0024] Preferably, before the recycled polyester textiles provided by this invention undergo hot pressing, the polyester textiles are dried in a forced-air environment at 50 to 60°C for 6 to 12 hours to reduce their moisture content. The dried polyester textiles are then subjected to hot pressing at a temperature of 265 to 275°C, a pressing pressure of 0.5 to 10 MPa, and a pressure holding time of 0.5 to 5 minutes. The selection of the above-mentioned pressing temperature, pressure, and holding time ensures that the polyester textiles can be hot-pressed into relatively dense sheets.

[0025] S102: After the dense PET sheet is cooled by hot pressing, it is mixed with an epoxy tackifier and then pulverized.

[0026] Specifically, in the process of processing the dense PET sheet after hot pressing provided by this invention, the hot-pressed sheet is cooled to below 50°C using air cooling. After cooling, an epoxy tackifier is mixed in and then pulverized to obtain powder or granules. The epoxy tackifier accounts for 0.5% to 4% of the weight percentage of the mixed material.

[0027] This invention relates to an epoxy tackifier for recycling polyester textiles to produce fused deposition modeling (FDM) filaments. Its main component is a copolymer of polystyrene and its derivatives with glycidyl methacrylate and its derivatives, and its molecular structure is as follows:

[0028]

[0029] Wherein, R1, R2, R3, R4, and R5 can be H, CH3, or long-chain alkane groups. The epoxy tackifier described in this invention has a weight-average molecular weight of 6000 to 8000 and an epoxy equivalent of 300 to 500 g / mol. Measurements showed that the required reaction temperature varies slightly depending on the epoxy tackifier selected, but generally the required reaction temperature is 170 to 330°C.

[0030] The design of the polystyrene and its derivative copolymerization part is mainly to improve the compatibility of epoxy tackifier with PET in polyester textiles; the design of the glycidyl methacrylate and its derivative copolymerization part is mainly to utilize epoxy groups to participate in the chain extension reaction of PET in polyester textiles, improve the viscoelasticity of recycled PET during extrusion processing, improve the extrusion processing performance of recycled PET, and ensure the continuous production of fused deposition modeling 3D printing filaments.

[0031] S103: The powder or particles produced after crushing are extruded into fused deposition 3D printing filaments to produce fused deposition 3D printing filaments.

[0032] Specifically, the extruder is a single-screw extruder with a screw speed of 40 to 60 rpm. The extruder feed temperature is 50 to 80°C. Because the previous step S102 only involved pulverization after mixing, the temperature did not reach the reaction temperature required by the epoxy tackifier, so the epoxy tackifier did not react. To ensure sufficient reaction of the epoxy tackifier, this step requires maintaining the required reaction temperature during extrusion molding. Therefore, the extruder barrel temperature in this step is controlled within the required reaction temperature range of the epoxy tackifier, i.e., within the range of 170 to 330°C. In this invention, a barrel temperature of 220 to 250°C is recommended. The die temperature is 200 to 220°C. By selecting the above temperature range and screw speed, the chain extension reaction between PET in polyester textiles and the epoxy tackifier is ensured, and a suitable melt viscosity is maintained, which is beneficial for molding into fused deposition modeling 3D printing filaments.

[0033] In summary, this invention utilizes a hot-pressing process to recycle polyester textiles, overcoming the difficulty of processing loose waste textiles and improving the extrusion processing stability of recycled PET materials. It also employs an epoxy tackifier to enhance the elasticity of the recycled PET melt, thereby improving the extrusion processing stability and the mechanical properties of 3D printed parts. Furthermore, this invention enables the production of high-value-added fused deposition modeling (FDM) 3D printing filaments using low-cost waste polyester textiles as raw materials. Finally, this invention provides profit margins for polyester textile recycling, increases the recycling rate of polyester textiles, reduces environmental pollution caused by polyester textiles, and lowers the production cost of fused deposition modeling filaments produced from recycled polyester textiles while maintaining a certain level of mechanical strength.

[0034] Two more specific embodiments are given below, and Table 1 discloses the main 3D printing parameter settings used in the embodiments.

[0035] Table 1 Main 3D Printing Parameter Settings

[0036]

[0037] Example 1

[0038] The method for producing fused deposition modeling 3D printing filaments from recycled polyester textiles in this embodiment includes the following steps:

[0039] Step 1: Dry the polyester textile at 60°C for 12 hours, and weigh the dried polyester textile. Assume the weight is g0.

[0040] Step 2: The dried polyester textiles are subjected to hot pressing molding. The temperature of the upper and lower plates of the hot press is set to 270℃, the hot pressing holding pressure is set to 5MPa, and the pressure holding time is set to 2 minutes.

[0041] Step 3: Cool the hot-pressed dense PET sheet to 25°C using air;

[0042] Step 4: Weigh the epoxy tackifier and mix it with the dense PET sheet; the selected epoxy tackifier has a weight average molecular weight of 7250, an epoxy equivalent of 310, a weight percentage of 1%, and a required reaction temperature of 220 to 300℃.

[0043] The weight percentage is the sum of the weight of the epoxy tackifier g1 and the weight of the polyester textile in step 1 g0, i.e., g1 / (g0+g1) = 1% in this embodiment.

[0044] Step 5: Mechanically pulverize the dense PET sheet with epoxy tackifier at a speed of 8000 rpm for 2 minutes to obtain a mixed PET powder containing 1% epoxy tackifier.

[0045] Step 6: The mixed PET powder containing 1% epoxy tackifier is fused deposition modeled into 3D printing filaments. The feed temperature of the extruder is 50℃, the barrel temperature is 230℃, the die temperature is 210℃, and the screw speed is 60rpm.

[0046] Step 7: Cool and wind up the continuously extruded 1.75mm diameter filament to obtain fused deposition modeling (FDM) 3D printing filament;

[0047] Step 8: 3D print the fused deposition modeling filament. According to ISO 527-2 / 5A / 10 standard, the tensile strength of the fused deposition modeling filament material produced from recycled polyester textiles is measured to be 41 MPa, and its elongation at break is 12%.

[0048] Example 2

[0049] Step 1: Dry the polyester textile at 60°C for 12 hours, and weigh the dried polyester textile. Assume the weight is g0.

[0050] Step 2: The dried polyester textiles are subjected to hot pressing molding. The temperature of the upper and lower plates of the hot press is set to 265℃, the hot pressing holding pressure is set to 10MPa, and the pressure holding time is set to 1 minute.

[0051] Step 3: Cool the hot-pressed dense PET sheet to 25°C using air;

[0052] Step 4: Weigh the epoxy tackifier and mix it with the dense PET sheet; the selected epoxy tackifier has a weight average molecular weight of 7100, an epoxy equivalent of 485, a weight percentage of 2%, and a required reaction temperature of 200 to 300℃.

[0053] The weight percentage is the sum of the weight of the epoxy tackifier g1 and the weight of the polyester textile in step 1 g0, i.e., g1 / (g0+g1) = 2% in this embodiment.

[0054] Step 5: Mechanically pulverize the dense PET sheet with epoxy tackifier at a speed of 8000 rpm for 1 minute to obtain a mixed PET powder containing 2% epoxy tackifier.

[0055] Step 6: The mixed PET powder containing 2% epoxy tackifier is fused deposition modeled into 3D printing filaments. The feed temperature of the extruder is 50℃, the barrel temperature is 250℃, the die temperature is 230℃, and the screw speed is 40rpm.

[0056] Step 7: Cool and wind up the continuously extruded 1.75mm diameter filament to obtain fused deposition modeling (FDM) 3D printing filament;

[0057] Step 8: 3D print the fused deposition modeling filament. According to ISO 527-2 / 5A / 10 standard, the tensile strength of the fused deposition modeling filament material produced from recycled polyester textiles is measured to be 41 MPa, and its elongation at break is 13%.

[0058] refer to Figure 2 This diagram illustrates the melt elastic modulus G' of recycled PET material after 3D printing, as provided in this embodiment of the invention. The data is obtained using a dynamic rheometer, which measures the viscoelasticity of the material. The horizontal axis represents the rotor angular velocity of the dynamic rheometer. Based on this angular velocity, the rotor applies shear stress to the melt material. This stress results in a corresponding reaction force, which is the viscoelastic resistance. This reaction force is used to determine the viscoelasticity of the material in its molten state and to measure changes in the material during processing. This reaction force is decomposed into a complex elastic modulus G' and a viscous modulus. The elastic modulus G' is... Figure 2The described content mainly refers to indicators that measure the melt elasticity of materials. Epoxy tackifiers can increase the melt elastic modulus G' of recycled PET materials, improve the viscoelasticity of recycled PET during extrusion processing, enhance the extrusion processing performance of recycled PET, and ensure continuous production of fused deposition modeling (FDM) filaments. Figure 3 The tensile fracture surface of the 3D printed part provided in the embodiment of the present invention. Figure 3 (a) and (c) are cross-sectional views of Example 1, (b) and (d) are cross-sectional views of Example 2, (c) is an enlarged view of (a), and (d) is an enlarged view of (b). The Examples 1 and 2 provided by the present invention show less printing gap on the tensile fracture surface of their 3D printed parts, indicating that their 3D printing quality is high, which is beneficial to improving their mechanical properties. Furthermore, the fracture surface has a continuous fish-scale radial texture, indicating that the material has a certain toughness.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0060] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for producing fused deposition modeling (FDM) 3D printing filaments from recycled polyester textiles, characterized in that, The method includes: Step 1: Perform hot pressing on polyester textiles to obtain dense PET sheets; Step 2: After the dense PET sheet is hot-pressed and cooled, an epoxy tackifier is mixed in, followed by pulverization. The epoxy tackifier is a copolymer of polystyrene and its derivatives with glycidyl methacrylate and its derivatives. The epoxy tackifier accounts for 0.5% to 2% of the total weight of the mixture. The structural formula of the epoxy tackifier is as follows, wherein R1, R2, R3, R4, and R5 can be H, CH3, or long-chain alkane groups. ； Step 3: Extrude the powder or granules produced after crushing into fused deposition 3D printing filaments to produce fused deposition 3D printing filaments; When hot pressing is performed in step 1, the hot pressing temperature is 265 to 275°C, the molding pressure is 0.5 to 10 MPa, and the pressure holding time is 0.5 to 5 minutes. Step 1 further includes: before hot pressing the polyester textiles, drying them in a forced-air dryer at 50 to 60°C for 6 to 12 hours to reduce their moisture content. Step 2 specifically includes: cooling the hot-pressed dense PET sheet to below 50°C, mixing it with an epoxy tackifier, and then pulverizing it to obtain powder or granules; The epoxy tackifier has a weight-average molecular weight of 6,000 to 10,000, an epoxy equivalent of 300 to 500 g / mol, and a required reaction temperature of 170 to 330°C. In step 3, during extrusion molding, the barrel temperature of the extruder is controlled within the required reaction temperature range of the epoxy tackifier.

2. The method for producing fused deposition modeling (FDM) filaments from recycled polyester textiles according to claim 1, characterized in that, In step 3, the feed temperature of the extruder is 20 to 80°C, the barrel temperature is 220 to 265°C, and the die temperature is 200 to 240°C.

3. The method for producing fused deposition modeling (FDM) filaments from recycled polyester textiles according to claim 1, characterized in that, In step 3, the extruder is a single-screw extruder with a screw speed of 40 to 60 rpm.

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