Plant fiber modified 3D printing material and preparation method thereof

Abstract

The application relates to the technical field of 3D printing materials, in particular to a plant fiber modified 3D printing material and a preparation method thereof, which is prepared from the following raw materials in parts by weight: polylactic acid, plant fiber powder, polybutylene succinate, porous spherical calcium carbonate, ethylene-acrylic acid copolymer, sodium alginate, cellulose acetate, plant type nanocrystal, crosslinking agent and lubricant; the plant type nanocrystal is composed of cellulose nanocrystal, silicon nanocrystal and hydroxyapatite nanocrystal; the material flows more smoothly in the nozzle by using the above formula, so that the problems of easy clogging, empty printing or winding of the fused or light-cured nozzle when printing a small line diameter are effectively avoided, the batch rejection rate is reduced, and the production efficiency is improved. In the post-stretching refinement process, even if the stretching parameters are adjusted in a larger range, the problems of over-stretching and easy breaking, under-stretching and insufficient strength do not easily occur, so that the quality and performance of the 3D printing surgical suture are ensured.

Description

Technical Field

[0001] This application relates to the field of 3D printing materials technology, and more specifically, to a plant fiber modified 3D printing material and its preparation method. Background Technology

[0002] Surgical sutures are medical threads used to close wounds, connect tissues, or ligate blood vessels. Traditional surgical sutures rely on hot drawing or braiding processes, mass-produced in uniform molds, resulting in round cross-sections and simple structures, fulfilling only the single function of "suturing." Their diameter and mechanical properties are affected by batch fluctuations, with tolerances often exceeding ±0.02mm. Knotting requires manual intervention, and surgical time increases linearly with suture length. 3D-printed sutures, on the other hand, replace molds with digital additive manufacturing. By adding material layer by layer through a CAD model, barbs, micropores, cavities, or multi-material gradients can be integrated into a single suture, achieving multi-task integration of "suturing-anchoring-drug release-sensing." Printing accuracy can be controlled to ±0.005mm, and the suture diameter, barb density, and local reinforcement areas can be adjusted in real time according to the patient's anatomical data, truly achieving "tailor-made sutures." In terms of mechanical performance, the shear stiffness of 3D-printed barbed structures is 10-20 times higher than that of traditional filaments of the same specifications, and their breaking strength is significantly superior. At the same time, shape memory polymers can automatically shrink upon body temperature triggering, maintaining constant tension, reducing manual adjustment and secondary knotting, and shortening surgical time by 20-40%. Traditional product inventory relies on large-scale forecasting, and specification changes require the creation of new molds; 3D printing, on the other hand, involves zero inventory and on-demand production. A single desktop device can complete the closed loop from scanning to filament formation within 30 minutes, making it particularly suitable for wartime, grassroots, or space emergency medical care.

[0003] However, in actual production, the microscale process of 3D printed surgical sutures is unstable. When the target suture diameter is reduced to the level of 0.05mm, the melting or photopolymerization nozzle is prone to clogging, dry firing, or tangling, resulting in a high batch scrap rate. The process window for the post-stretching and refining step is narrow. Overstretching can easily lead to breakage, while understretching results in insufficient strength. These defects severely limit the large-scale application of 3D printed surgical sutures. Summary of the Invention

[0004] To address the issues of unstable microscale processes, breakage due to overstretching, and insufficient strength due to understretching in 3D-printed surgical sutures, this application provides a plant fiber-modified 3D printing material and its preparation method.

[0005] In the first aspect, this application provides a plant fiber modified 3D printing material, which adopts the following technical solution:

[0006] A plant fiber modified 3D printing material is prepared from the following raw materials in parts by weight:

[0007] 30-40 parts of polylactic acid

[0008] 15-20 parts of plant fiber powder

[0009] 10-15 parts of polybutylene succinate

[0010] 5-10 parts of porous spherical calcium carbonate

[0011] 3-4 parts of ethylene-acrylic acid copolymer

[0012] 2-4 parts sodium alginate

[0013] 3-5 parts of cellulose acetate

[0014] 4-6 parts of plant-based nanocrystals

[0015] 1-2 parts of crosslinking agent

[0016] Lubricant 0.5-1 part

[0017] The plant-type nanocrystals are composed of cellulose nanocrystals, silicon nanocrystals, and hydroxyapatite nanocrystals.

[0018] By adopting the above technical solution, the material flows more smoothly in the nozzle, effectively avoiding problems such as easy clogging, dry firing, or thread tangling that occur when printing fine wire diameters in molten or photocurable nozzles, thus reducing batch scrap rates and improving production efficiency. Simultaneously, during the post-stretching and refining process, even with adjustments to stretching parameters over a wide range, overstretching leading to breakage or understretching resulting in insufficient strength is less likely to occur, thereby ensuring the quality and performance of 3D printed surgical sutures.

[0019] The addition of plant fiber powder, porous spherical calcium carbonate, and lubricant effectively improved the material's flowability, dispersibility, and lubricity. Plant fiber powder increased the material's coefficient of friction, allowing for smoother flow in the nozzle and reducing buildup and clogging. The porous structure of the porous spherical calcium carbonate adsorbed impurities and moisture, while its spherical particle shape promoted uniform flow and prevented filament tangling. The lubricant further reduced friction between the material and the nozzle, ensuring smooth extrusion. Furthermore, the addition of polybutylene succinate and plant-based nanocrystals improved the material's thermal stability and thermal conductivity, enabling more uniform heating during printing and reducing localized overheating or uneven cooling. This lowered the risk of nozzle clogging and filament tangling, significantly improving the stability of the 3D printing process.

[0020] Simultaneously, by rationally proportioning raw materials such as polylactic acid (PLA), plant fiber powder, plant-based nanocrystals, and ethylene-acrylic acid copolymer, the tensile properties and flexibility of the material were optimized. The molecular chain structure of PLA can better rearrange during stretching, improving tensile strength and toughness; the presence of plant fiber powder can effectively disperse stress and reduce stress concentration points, thereby improving the tensile strength and toughness of the material; plant-based nanocrystals increase the crystallinity of the material, further optimizing tensile properties; and the ethylene-acrylic acid copolymer imparts good flexibility and elasticity to the material, buffering tensile force and preventing excessive stretching and breakage. The network structure formed by sodium alginate also enhances the material's flexibility and adapts to the stretching process. These improvements broaden the process window for the post-stretching refinement step, reducing the material scrap rate caused by improper stretching.

[0021] The addition of polybutylene succinate significantly improves the fracture strength and shear stiffness of 3D-printed surgical sutures. The shear stiffness of the barbed structure is 10-20 times higher than that of traditional sutures of the same specifications, and the fracture strength also significantly surpasses that of traditional sutures, better meeting the requirements of surgical suturing. The reinforcing effect of plant fiber powder and plant-based nanocrystals further enhances the mechanical properties while maintaining good biocompatibility. The high crystallinity and high strength of cellulose nanocrystals allow them to be uniformly distributed in the material, effectively dispersing stress and thus significantly improving the tensile strength and modulus of the surgical suture. The addition of silicon nanocrystals further enhances the material's hardness and wear resistance, strengthening the suture's fracture resistance. Hydroxyapatite nanocrystals impart good toughness to the material, enabling it to better withstand external forces during stretching. The synergistic effect of these three components allows the surgical suture to maintain high strength while possessing good flexibility, better meeting the mechanical requirements of surgical suturing. Furthermore, the high thermal stability of cellulose nanocrystals broadens the material's processing temperature range, making the material less prone to decomposition or denaturation during 3D printing, improving printing stability and reliability. Silicon nanocrystals improve the thermal conductivity of materials, resulting in more uniform heating during printing and reducing problems such as localized overheating or uneven cooling. Their hardness also reduces nozzle wear. Furthermore, cellulose nanocrystals, silicon nanocrystals, and hydroxyapatite nanocrystals all exhibit good biocompatibility, reducing rejection and inflammatory reactions in human tissues to sutures.

[0022] Preferably, the weight ratio of the cellulose nanocrystals, the silicon nanocrystals, and the hydroxyapatite nanocrystals is (0.5-2):(2-4):1.

[0023] By employing the above-mentioned technical solution and adjusting the ratio of cellulose nanocrystals, silicon nanocrystals, and hydroxyapatite nanocrystals, the thermal stability and biocompatibility of the material can be optimized while ensuring its mechanical properties. The addition of these composite nanocrystals achieves an optimal balance in terms of strength, toughness, biocompatibility, and tissue repair capacity in surgical sutures, further enhancing their overall performance and enabling them to better meet the needs of clinical medicine.

[0024] Preferably, the plant fiber powder is prepared by the following method:

[0025] 1) Prepare a strong alkaline solution with a concentration of 1-5wt%, add plant fiber, stir and grind at 50-60℃ to obtain a plant fiber suspension, filter, wash and obtain the first plant fiber powder;

[0026] 2) Mix the plant fiber powder and softened water, stir at 50-60℃ to obtain a plant fiber suspension, filter and rinse to obtain a second plant fiber powder. The softened water is composed of potassium permanganate, fatty alcohol polyoxyethylene ether and water in a weight ratio of 1:(3-5):15.

[0027] 3) Place the second plant fiber powder under a pressure of 1.5-1.6 MPa and a temperature of 50-60℃ for 10-15 minutes, then release the pressure instantly. Mix the released second plant fiber powder with an ethanol solution, then add an aminosilane coupling agent, stir evenly, and then ultrasonically stir for 40-60 minutes.

[0028] By adopting the above technical solution, the surface activity and binding force with polylactic acid of the treated plant fiber powder are enhanced, which can better disperse stress, improve the tensile strength and fracture strength of 3D printing materials, and enable 3D printing materials to meet the high strength requirements of surgical sutures while maintaining good flexibility.

[0029] Plant fibers are stirred and ground in a 1-5 wt% strong alkaline solution at 50-60℃. This process disrupts the fiber's crystalline structure, increases its specific surface area, and facilitates uniform dispersion in subsequent 3D printing materials. This avoids printing defects caused by fiber agglomeration and improves the compatibility between the fiber and the 3D printing material. Simultaneously, the strong alkaline solution treatment opens some crystalline regions of the plant fibers and increases the number of hydroxyl groups on the fiber surface, forming more active sites and providing a foundation for subsequent chemical reactions and surface modification. The second step involves placing the plant fiber powder under pressure of 1.5-1.6 MPa at 50-60℃ for 10-15 minutes, followed by instantaneous pressure release. This makes the internal structure of the fiber more compact, enhancing its mechanical strength. Furthermore, the instantaneous pressure release creates micropores on the fiber surface, increasing the bonding force between the fiber and the 3D printing material, further improving the overall mechanical properties of the composite material and thus enhancing the fiber's toughness and strength.

[0030] Softening water introduces more active groups such as hydroxyl groups onto the fiber surface, enhancing its surface activity and chemical reactivity. This facilitates bonding with aminosilane coupling agents, strengthening the fiber's internal structure and improving its tensile and compressive strength. Fatty alcohol polyoxyethylene ethers reduce friction between fibers, making them less prone to breakage during processing, thus maintaining fiber integrity and enhancing toughness. Aminosilane coupling agents react with the hydroxyl groups on the plant fiber surface through chemical bonding, allowing the plant fiber powder to effectively bond with functional groups in matrix materials such as polylactic acid, significantly improving the interfacial bonding strength between the fiber and the matrix.

[0031] Preferably, the concentration of the aminosilane coupling agent in the ethanol solution is 15-30 g / L.

[0032] By adopting the above technical solution, it is possible to ensure that the coupling agent forms a uniform coating layer on the fiber surface, significantly enhancing the compatibility between the fiber and polylactic acid, increasing the tensile strength and breaking strength of the material, while maintaining good flexibility.

[0033] Preferably, the average particle size of the porous spherical calcium carbonate is 20-60 nm.

[0034] By adopting the above technical solution, the average particle size of porous spherical calcium carbonate is optimized, resulting in a very high specific surface area. This enables highly uniform dispersion in 3D printing materials, avoiding material property inhomogeneity caused by particle agglomeration. Because the calcium carbonate particles are uniformly distributed within the material, nozzle clogging or printing defects caused by material inhomogeneity are reduced. Simultaneously, it effectively disperses stress, improving the tensile strength and fracture toughness of the material.

[0035] Preferably, the ethylene-acrylic acid copolymer contains 10%-30% acrylic acid and has a molecular weight of 5000-20000.

[0036] By adopting the above technical solution and optimizing the parameters of the ethylene-acrylic acid copolymer, the copolymer maintains both flexibility and strength, which helps improve the tensile properties and flexibility of the material, making it less prone to breakage. Simultaneously, a molecular weight between 5000 and 20000 helps improve the flowability and processability of the plant fiber modified 3D printing material during the printing process, enabling it to pass smoothly through the nozzle and reducing clogging issues.

[0037] Preferably, the crosslinking agent is composed of triallyl isocyanurate and trimethylolpropane triisobutylene ester in a weight ratio of 1:(2-4).

[0038] The multifunctional nature of trimethylolpropane triisobutylene ester allows it to form more crosslinking points with matrix materials such as polylactic acid and ethylene-acrylic acid copolymers; triallyl isocyanurate further enhances the stability of the network. The combined use of these two materials significantly increases the crosslinking density, thereby improving its mechanical properties, including tensile strength and elongation at break. Simultaneously, the higher crosslinking density allows the material to better disperse stress under load, reducing stress concentration points and thus improving toughness and fatigue resistance. This is particularly important for surgical sutures that withstand repeated tensile and bending stresses during suturing. The crosslinking network of triallyl isocyanurate and trimethylolpropane triisobutylene ester also improves the material's thermal stability, enabling it to withstand higher temperatures during 3D printing without thermal decomposition.

[0039] Preferably, the lubricant includes at least one of zinc stearate, calcium stearate, and stearic acid.

[0040] By adopting the above technical solutions and optimizing the type of lubricant, the coefficient of friction between the material and the inner wall of the nozzle can be reduced, ensuring smooth material flow within the nozzle and reducing accumulation and clogging caused by friction. This effectively avoids nozzle dry-printing or filament entanglement problems. This not only significantly improves the stability of the 3D printing process but also reduces batch scrap rates and increases production efficiency. Furthermore, the addition of lubricant helps optimize the post-stretching refinement process, making the material easier to handle during stretching, further widening the process window, and ensuring the quality and performance of the final product.

[0041] Secondly, this application provides a method for preparing plant fiber modified 3D printing materials, using the following technical solution:

[0042] A method for preparing a plant fiber modified 3D printing material includes the following preparation steps:

[0043] S1. Add 1 / 2 polylactic acid, porous spherical calcium carbonate, sodium alginate, cellulose acetate, plant-type nanocrystals, plant fiber powder, ethylene-acrylic acid copolymer, crosslinking agent and lubricant to a high-speed mixer and stir. Then put it into a twin-screw extruder for melt blending and extrusion to obtain slices.

[0044] S2. After dry mixing 1 / 2 polylactic acid, polybutylene succinate and chips in a high-speed mixer, add them to a twin-screw extruder for melt mixing, extrusion, cooling, pelletizing and drying to obtain plant fiber modified 3D printing material.

[0045] By adopting the above technical solution, the preparation method of this plant fiber modified 3D printing material ensures the uniform distribution of each component and the optimization of material properties through stepwise mixing, twin-screw extrusion and other processes. At the same time, it is suitable for large-scale production and personalized customization, providing a strong guarantee for the high-quality production of 3D printed surgical sutures.

[0046] Preferably, in step S1, the extruder temperature is set as follows: Section 1 165-170℃, Section 2 170-175℃, Section 3 175-180℃, Section 4 180-185℃, Section 5 180-185℃, Section 6 180-185℃, Section 7 170-175℃, Section 8 160-170℃, Section 9 165-170℃, the die temperature is 160-165℃, and the screw speed is 200-400 rpm.

[0047] In step S2, the extruder temperature is set as follows: Section 1 165-170℃, Section 2 170-175℃, Section 3 175-180℃, Section 4 175-180℃, Section 5 165-170℃, Section 6 165-170℃, Section 7 160-165℃, Section 8 160-165℃, Section 9 150-155℃, the die temperature is 145-150℃, and the screw speed is 120-150 rpm.

[0048] By adopting the above technical solutions and precisely controlling the temperature and screw speed, it is possible to ensure that components such as plant fiber powder, porous spherical calcium carbonate, and plant-type nanocrystals are uniformly dispersed in the material. This can reduce defects in the material during melting and cooling processes, such as bubbles and impurity agglomeration. At the same time, precise process parameter settings can reduce batch differences caused by different processing conditions and improve the stability and reliability of the material.

[0049] In summary, this application has the following beneficial effects:

[0050] 1. The formulation in this application allows the plant fiber-modified 3D printing material to flow more smoothly in the nozzle, effectively avoiding common problems such as nozzle clogging, dry printing, or tangling when printing fine wire diameters. This significantly reduces batch scrap rates and improves production efficiency. During the post-stretching and refining process, the material exhibits a wider processing window. Even when adjusting stretching parameters within a wide range, it is less prone to overstretching and breakage or understretching and insufficient strength, ensuring the high quality and excellent performance of 3D printed surgical sutures. Detailed Implementation

[0051] Example

[0052] Polylactic acid is NatureWorks 2003D from the United States.

[0053] The plant fiber powder is made from finely polished sisal fiber.

[0054] The polybutylene succinate was purchased from Shanghai Kanglang Biotechnology Co., Ltd., model number LAC-6R-860.

[0055] Example 1

[0056] A plant fiber-modified 3D printing material is prepared by the following method:

[0057] S1. Add 150g of 1 / 2 polylactic acid, 50g of porous spherical calcium carbonate, 20g of sodium alginate, 30g of cellulose acetate, 40g of plant-type nanocrystals, 150g of plant fiber powder, 30g of ethylene-acrylic acid copolymer, 10g of crosslinking agent and 5g of lubricant (zinc stearate) to a high-speed mixer and stir. Then put it into a twin-screw extruder for melt blending and extrusion to obtain slices.

[0058] The plant-type nanocrystals are composed of cellulose nanocrystals, silicon nanocrystals, and hydroxyapatite nanocrystals in a weight ratio of 0.5:2:1; the average particle size of the porous spherical calcium carbonate is 20 nm.

[0059] The ethylene-acrylic acid copolymer contains 10% acrylic acid and has a molecular weight of 5000.

[0060] The crosslinking agent is composed of triallyl isocyanurate and trimethylolpropane triisobutylene ester in a weight ratio of 1:2;

[0061] In step S1, the extruder temperature is set as follows: Section 1 165℃, Section 2 170℃, Section 3 175℃, Section 4 180℃, Section 5 180℃, Section 6 180℃, Section 7 170℃, Section 8 165℃, Section 9 165℃, the die temperature is 160℃, and the screw speed is 200 rpm.

[0062] S2. Mix 150g of 1 / 2 polylactic acid, 200g of polybutylene succinate and the chips in a high-speed mixer, then add them to a twin-screw extruder for melt mixing, extrusion, cooling, pelletizing and drying to obtain plant fiber modified 3D printing material.

[0063] In step S2, the extruder temperature is set as follows: 165℃ for section 1, 170℃ for section 2, 175℃ for section 3, 175℃ for section 4, 165℃ for section 5, 165℃ for section 6, 160℃ for section 7, 165℃ for section 8, and 150℃ for section 9; the die temperature is 145℃; and the screw speed is 120 rpm.

[0064] The difference between Examples 2-3 and Example 1 lies in the types, amounts, and parameters of raw materials used to prepare the plant fiber modified 3D printing materials. Specific differences are shown in Table 1.

[0065] Table 1. Raw material types, dosages, and parameters for preparing plant fiber modified 3D printing materials.

[0066]

[0067] Example 4

[0068] A plant fiber modified 3D printing material, the difference between this embodiment and embodiment 1 is that: the plant-type nanocrystals are composed of cellulose nanocrystals, silicon nanocrystals and hydroxyapatite nanocrystals in a weight ratio of 1:1:1.

[0069] Example 5

[0070] A plant fiber modified 3D printing material, the difference between this embodiment and Example 1 is that the crosslinking agent is triallyl isocyanurate.

[0071] Example 6

[0072] A plant fiber modified 3D printing material, the difference between this embodiment and Example 1 is that the crosslinking agent is bisphenol A diglycidyl ether.

[0073] Example 7

[0074] A plant fiber modified 3D printing material, the difference between this embodiment and Example 1 is that the acrylic acid content in the ethylene-acrylic acid copolymer is 5% and the molecular weight is 5000.

[0075] Example 8

[0076] A plant fiber modified 3D printing material, the difference between this embodiment and Example 1 is that the plant fiber powder is prepared by the following method:

[0077] 1) Prepare a 1 wt% sodium hydroxide solution, add 200 g of plant fiber, stir and grind at 50°C to obtain a plant fiber suspension, filter, and rinse to obtain the first plant fiber powder.

[0078] 2) Mix the plant fiber powder and softened water, stir at 50°C to obtain a plant fiber suspension, filter and rinse to obtain a second plant fiber powder. The softened water is composed of potassium permanganate, fatty alcohol polyoxyethylene ether and water in a weight ratio of 1:3:15.

[0079] 3) Place the second plant fiber powder under a pressure of 1.5 MPa and a temperature of 50°C for 10 minutes, then release the pressure instantly. Mix the released second plant fiber powder with an ethanol solution, then add an aminosilane coupling agent (γ-aminopropyltriethoxysilane), stir evenly, and then ultrasonically stir for 40 minutes.

[0080] The concentration of the aminosilane coupling agent (γ-aminopropyltriethoxysilane) in the ethanol solution is 15 g / L.

[0081] Example 9

[0082] A plant fiber modified 3D printing material, the difference between this embodiment and Example 1 is that the plant fiber powder is prepared by the following method:

[0083] 1) Prepare a 5wt% sodium hydroxide solution, add 200g of plant fiber, stir and grind at 60℃ to obtain a plant fiber suspension, filter, and rinse to obtain the first plant fiber powder;

[0084] 2) Mix the plant fiber powder and softened water, stir at 60°C to obtain a plant fiber suspension, filter and rinse to obtain a second plant fiber powder. The softened water is composed of potassium permanganate, fatty alcohol polyoxyethylene ether and water in a weight ratio of 1:5:15.

[0085] 3) Place the second plant fiber powder under a pressure of 1.6 MPa and a temperature of 60°C for 15 minutes, then release the pressure instantly. Mix the released second plant fiber powder with an ethanol solution, then add an aminosilane coupling agent (N-β-aminoethyl-γ-aminopropyltrimethoxysilane), stir evenly, and then ultrasonically stir for 60 minutes.

[0086] The concentration of the aminosilane coupling agent (N-β-aminoethyl-γ-aminopropyltrimethoxysilane) in the ethanol solution is 30 g / L.

[0087] Comparative Example

[0088] Comparative Example 1

[0089] A plant fiber modified 3D printing material, the difference between this comparative example and Example 1 is that: the plant-type nanocrystals are composed of cellulose nanocrystals and silicon nanocrystals in a weight ratio of 0.5:2.

[0090] Comparative Example 2

[0091] A plant fiber modified 3D printing material, the difference between this comparative example and Example 1 is that the plant-type nanocrystals are cellulose nanocrystals.

[0092] Comparative Example 3

[0093] A plant fiber modified 3D printing material, the difference between this comparative example and Example 1 is that nano-silica is used instead of plant-type nanocrystals.

[0094] Comparative Example 4

[0095] A plant fiber modified 3D printing material, the difference between this comparative example and Example 1 is that nano-silica is used instead of plant fiber powder.

[0096] Comparative Example 5

[0097] A plant fiber modified 3D printing material, the difference between this comparative example and Example 1 is that the ethylene-acrylic acid copolymer is removed.

[0098] Comparative Example 6

[0099] A plant fiber modified 3D printing material, the difference between this comparative example and Example 1 is that polybutylene succinate is removed.

[0100] Comparative Example 7

[0101] A plant fiber modified 3D printing material, the difference between this comparative example and Example 1 is that no crosslinking agent is added.

[0102] Detection methods / test methods

[0103] Nozzle clogging test:

[0104] 1) Equipment preparation: Preheat the 3D printer to the set printing temperature;

[0105] Install a pressure sensor and ensure it is tightly connected to the nozzle inlet to monitor pressure changes inside the nozzle in real time; load the plant fiber modified 3D printing materials of Examples 1-9 and Comparative Examples 1-7 into the feed port of the 3D printer respectively.

[0106] 2) Printing parameter settings

[0107] Set the same printing parameters, including a printing speed of 50 mm / s, a layer height of 0.2 m, and an infill density of 100%.

[0108] Ensure that the nozzle temperature and the printing platform temperature remain constant during the printing process.

[0109] 3) Printing process record

[0110] Plant fiber modified 3D printing materials from Examples 1-9 and Comparative Examples 1-7 were used for printing, and a standard cube model (20mm × 20mm × 20mm) was printed each time.

[0111] During the printing process, pressure changes within the nozzle are monitored in real time using a pressure sensor. When the pressure suddenly rises above a set threshold (exceeding 20% ​​of the normal pressure), it is recorded as a nozzle clogging event. Each material is printed at least 10 times, and the number of nozzle clogging events during each printing process is recorded. The fewer the number of clogging events, the better the printing stability of the material.

[0112] Post-stretching refinement process test:

[0113] 1) Testing equipment

[0114] Tensile testing machine: Model INSTRON-5960, accuracy ±0.001mm.

[0115] Microscope: Model Olympus BX51, used for measuring wire diameter, with an accuracy of ±0.005mm.

[0116] 2) Sample preparation

[0117] The filaments of the plant fiber modified 3D printing materials in Examples 1-9 and Comparative Examples 1-7 were printed using a 3D printer, with a filament diameter of 1.75 mm.

[0118] Print 10 samples for each material, ensuring that the initial wire diameter of the samples is consistent.

[0119] 3) Tensile testing machine settings

[0120] Adjust the clamps of the tensile testing machine to a spacing of 100mm.

[0121] Set the stretching speed to 10 mm / min and record the force and displacement during the stretching process.

[0122] 3) Tensile test

[0123] One end of each sample is fixed to the upper clamp of the tensile testing machine, and the other end is fixed to the lower clamp.

[0124] Start the tensile testing machine, record the fracture point, tensile ratio, and final wire diameter during the tensile process, and calculate the average fracture point, average tensile ratio, and average final wire diameter.

[0125] Use a microscope to measure the final wire diameter to ensure measurement accuracy. If the plant fiber modified 3D printing material does not break over a wider range of stretch ratios and has better uniformity in the final wire diameter, it indicates a wider window for subsequent stretching processes.

[0126] Batch stability testing:

[0127] Test equipment

[0128] 1) Micrometer: with an accuracy of ±0.001mm, used to measure wire diameter.

[0129] Universal testing machine: Model INSTRON-5960, accuracy ±0.01N, used to measure tensile strength.

[0130] Test steps

[0131] Sample preparation

[0132] Filaments of plant fiber modified 3D printing materials used in Examples 1-9 and Comparative Examples 1-7, produced in continuous batches of 50.

[0133] 2) Wire diameter measurement

[0134] Use a micrometer to measure the wire diameter of each sample and record the data.

[0135] The wire diameter was measured at three different locations for each sample, and the average value was taken as the wire diameter of that sample.

[0136] 3) Strength test

[0137] The tensile strength of each sample was measured using a universal testing machine.

[0138] Set the stretching speed to 10 mm / min, record the maximum force value during the stretching process, and calculate the tensile strength.

[0139] 4) Data Recording

[0140] For each batch, 50 samples were recorded for wire diameter and tensile strength. Using the first sample as the baseline, the number of samples with changes in wire diameter and tensile strength exceeding 5% was counted. Batch stability testing primarily assesses the fluctuations in wire diameter and tensile strength during continuous production. The fewer samples with changes exceeding 5% in wire diameter and tensile strength, the better the batch stability of the material. Experimental data are shown in Table 2.

[0141] Table 2. Experimental data of Examples 1-9 and Comparative Examples 1-7

[0142]

[0143]

[0144] The experimental data from Examples 1-9 and Comparative Examples 1-7 show that the plant fiber modified 3D printing materials of Examples 1-9 exhibit good performance in nozzle clogging test, post-stretching and refining process test, and batch stability test.

[0145] Examples 1-3 all had 1 nozzle clogging time, demonstrating good printing stability; Examples 4-7 had an increased number of nozzle clogging times, but were still better than the comparative examples; Examples 8 and 9 had 0 nozzle clogging times, demonstrating excellent printing stability. This indicates that by optimizing the types and amounts of each component in this application, the number of nozzle clogging times of the plant fiber modified 3D printing material can be effectively reduced, making it more stable in the 3D printing process.

[0146] Examples 1-3 showed a good balance in terms of average breaking point, stretch ratio, and final wire diameter, with stretch ratios between 4.0 and 4.2 and final wire diameters between 0.44 and 0.45 mm. Examples 4-7 showed a decrease in stretch ratio, but were still higher than the comparative example, with final wire diameters between 0.46 and 0.51 mm. This indicates that by optimizing the types and amounts of plant fiber powder, ethylene-acrylic acid copolymer, plant-based nanocrystals, and crosslinking agents, this application achieves good toughness and uniformity during the stretching process.

[0147] The average breaking point, stretching ratio, and final wire diameter of Comparative Examples 1-7 were all lower than those of the Examples, especially Comparative Examples 3 and 7, which had stretching ratios of 2.9 and 3.1, and final wire diameters of 0.59 mm and 0.56 mm, respectively. This indicates that the formulation of this application is not easy to break during stretching and has a uniform wire diameter.

[0148] The number of samples with wire diameter and tensile strength changes exceeding 5% in Examples 1-3 was relatively small, at 3-4 each, indicating that these formulations performed well in terms of batch stability. The number of samples with wire diameter and tensile strength changes exceeding 5% in Examples 4-7 increased, but was still better than the comparative examples. The number of samples with wire diameter and tensile strength changes exceeding 5% in Examples 8 and 9 was 0, indicating that by optimizing the type and amount of plant fiber powder, ethylene-acrylic acid copolymer, plant-type nanocrystals, and crosslinking agent, the stability of 3D printing can be effectively improved in this application.

[0149] The number of samples with wire diameter and tensile strength changes exceeding 5% in Comparative Examples 1-7 was significantly higher than in the Examples, especially Comparative Examples 3 and 7, which had 19 and 20 samples respectively. This indicates that the formulation of this application is not prone to parameter fluctuations during continuous production and has good stability.

[0150] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A plant fiber modified 3D printing material, characterized in that, It is prepared from the following raw materials in parts by weight: 30-40 parts of polylactic acid 15-20 parts of plant fiber powder 10-15 parts of polybutylene succinate 5-10 parts of porous spherical calcium carbonate 3-4 parts of ethylene-acrylic acid copolymer 2-4 parts sodium alginate 3-5 parts of cellulose acetate 4-6 parts of plant-based nanocrystals 1-2 parts of crosslinking agent Lubricant 0.5-1 part The plant-type nanocrystals are composed of cellulose nanocrystals, silicon nanocrystals and hydroxyapatite nanocrystals; The weight ratio of the cellulose nanocrystals, the silicon nanocrystals, and the hydroxyapatite nanocrystals is (0.5-2):(2-4):1; The plant fiber powder is prepared by the following method: 1) Prepare a strong alkaline solution with a concentration of 1-5wt%, add plant fiber, stir and grind at 50-60℃ to obtain a plant fiber suspension, filter, and wash to obtain the first plant fiber powder; 2) Mix the plant fiber powder and softened water, stir at 50-60℃ to obtain a plant fiber suspension, filter and rinse to obtain a second plant fiber powder. The softened water is composed of potassium permanganate, fatty alcohol polyoxyethylene ether and water in a weight ratio of 1:(3-5):

15. 3) Place the second plant fiber powder under a pressure of 1.5-1.6 MPa and a temperature of 50-60℃ for 10-15 minutes, then release the pressure instantly. Mix the released second plant fiber powder with an ethanol solution, then add an aminosilane coupling agent, stir evenly, and then ultrasonically stir for 40-60 minutes. The average particle size of the porous spherical calcium carbonate is 20-60 nm. The ethylene-acrylic acid copolymer contains 10%-30% acrylic acid and has a molecular weight of 5000-20000.

2. The plant fiber modified 3D printing material according to claim 1, characterized in that: The concentration of the aminosilane coupling agent in the ethanol solution is 15-30 g / L.

3. The plant fiber modified 3D printing material according to claim 1, characterized in that: The crosslinking agent is composed of triallyl isocyanurate and trimethylolpropane triisobutylene ester in a weight ratio of 1:(2-4).

4. The plant fiber modified 3D printing material according to claim 1, characterized in that: The lubricant includes at least one of zinc stearate, calcium stearate, and stearic acid.

5. A method for preparing a plant fiber modified 3D printing material as described in any one of claims 1-4, characterized in that, The preparation steps include the following: S1. Add 1 / 2 polylactic acid, porous spherical calcium carbonate, sodium alginate, cellulose acetate, plant-type nanocrystals, plant fiber powder, ethylene-acrylic acid copolymer, crosslinking agent and lubricant to a high-speed mixer and stir. Then put it into a twin-screw extruder for melt blending and extrusion to obtain slices. S2. After dry mixing 1 / 2 polylactic acid, polybutylene succinate and chips in a high-speed mixer, add them to a twin-screw extruder for melt mixing, extrusion, cooling, pelletizing and drying to obtain plant fiber modified 3D printing material.

6. The method for preparing a plant fiber modified 3D printing material according to claim 5, characterized in that: In step S1, the extruder temperature is set as follows: Section 1 165-170℃, Section 2 170-175℃, Section 3 175-180℃, Section 4 180-185℃, Section 5 180-185℃, Section 6 180-185℃, Section 7 170-175℃, Section 8 160-170℃, Section 9 165-170℃, the die temperature is 160-165℃, and the screw speed is 200-400 rpm. In step S2, the extruder temperature is set as follows: Section 1 165-170℃, Section 2 170-175℃, Section 3 175-180℃, Section 4 175-180℃, Section 5 165-170℃, Section 6 165-170℃, Section 7 160-165℃, Section 8 160-165℃, Section 9 150-155℃, the die temperature is 145-150℃, and the screw speed is 120-150 rpm.

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