PBT 3D printing material and preparation method thereof

Abstract

The invention discloses a PBT 3D printing material and a preparation method thereof, and relates to the field of high polymer materials. The PBT 3D printing material is prepared from the following components in parts by weight: 80 to 95 parts of PBT resin, 5 to 20 parts of terpolymer glycidyl ester, 0.1 to 1 part of antioxidant, and 0 to 5 parts of optional components and other auxiliary agents. According to the PBT 3D printing material, terpolymer glycidyl ester with specific composition and molecular weight is creatively introduced as a crystallization regulator of PBT, and an epoxy functional group in a molecular chain of the terpolymer glycidyl ester chemically reacts with a terminal carboxyl group or a terminal hydroxyl group of PBT to form a grafted or crosslinked structure, so that the movement ability of the PBT molecular chain is effectively limited, but crystallization of the PBT molecular chain is not completely inhibited; the final crystallinity of the material is accurately controlled in a proper range of 25%-40% instead of being singly improved or reduced.

Description

Technical Field

[0001] This invention relates to the field of polymer materials, and in particular to a PBT 3D printing material and its preparation method. Background Technology

[0002] Polybutylene terephthalate (PBT) is an excellent semi-crystalline thermoplastic engineering plastic with superior mechanical properties, chemical resistance, electrical insulation, and processing flowability, making it widely used in the automotive, electronics, and electrical industries. As a semi-crystalline polyester material, PBT, with its low water absorption and high dimensional stability, is theoretically suitable for the high-precision molding requirements of 3D printing. PBT resin with an intrinsic viscosity of 0.9–1.0 dL / g, in particular, combines good processing flowability with mechanical strength, making it one of the preferred substrates for 3D printing materials. In recent years, with the rapid development of 3D printing technology, the application of PBT in fused deposition modeling (FDM) technology has attracted widespread attention, promising the rapid fabrication of complex structural engineering parts.

[0003] However, the inherent rapid crystallization characteristic of PBT poses a significant challenge to the FDM printing process, severely limiting its large-scale application in the 3D printing field. The specific problems are as follows:

[0004] 1. Large crystallization shrinkage: PBT will produce a large volume shrinkage during the cooling and crystallization process from the melt. This shrinkage can easily cause the product to warp, deform, or even fall off the printing platform in the FDM process of layer-by-layer printing, resulting in a high printing failure rate. This is the core pain point that restricts the use of PBT for FDM printing.

[0005] 2. Narrow Processing Window: PBT's crystallization temperature (Tc) and melting point (Tm) are relatively close, and its supercooling (Tm-Tc) is small. This means that the melt crystallizes rapidly after extrusion, resulting in a short interlayer bonding time. If the printing platform temperature is set too low, crystallization will be too fast, leading to weak interlayer adhesion; if set too high, the product will solidify slowly and is prone to collapse. This narrow processing window places extremely stringent requirements on printing parameter settings. The printing process window width for ordinary pure PBT is typically less than 5°C, resulting in extremely poor process adaptability.

[0006] 3. Poor performance stability: Uneven cooling conditions during the printing process can lead to large differences in crystallinity among different parts of the product, resulting in uneven distribution of internal stress and anisotropy of performance. This affects the dimensional accuracy and mechanical property stability of the final product, making it difficult to meet the requirements of engineering components.

[0007] Currently, methods to improve PBT printing performance mainly include adding inorganic nucleating agents (such as talc and montmorillonite) and polymer toughening agents (such as elastomers). While adding nucleating agents can refine grains, it often further accelerates the crystallization rate, exacerbating the risk of warping. On the other hand, adding elastomers can improve toughness, but it usually reduces the material's rigidity and heat resistance, and the control over crystallinity is not precise enough, failing to fundamentally solve the FDM printing challenges of PBT.

[0008] Furthermore, some technologies attempt to improve PBT performance by adding inorganic modifiers, but the problem of poor compatibility between the modifiers and the PBT matrix remains unresolved, leading to phase separation and a decline in the material's mechanical properties. While inorganic particles modified with silane coupling agents can improve compatibility with polyester materials, how to synergize with crystallization regulators to achieve the dual effects of crystallization control and performance improvement remains a pressing technical problem to be solved in this field.

[0009] Therefore, developing a new method that can effectively control the crystallization kinetics and final crystallinity of PBT to fundamentally solve its FDM printing challenges, while taking into account the material's mechanical properties, heat resistance, and processing fluidity, has significant industrial application value. Summary of the Invention

[0010] The purpose of this invention is to provide a PBT 3D printing material and its preparation method to solve the problems mentioned in the background art.

[0011] To achieve the above objectives, the present invention provides the following technical solution: a PBT 3D printing material, which, by weight, is composed of the following components: 80-95 parts of PBT resin, 5-20 parts of ternary copolymer glycidyl ester, 0.1-1 parts of antioxidant, and 0-5 parts of optional other additives;

[0012] The other additives are one or two of lubricants and pigments, which can be selectively added according to actual printing needs;

[0013] The ternary copolymer glycidyl ester is a ternary copolymer of glycidyl methacrylate, ethylene and methyl acrylate. The ternary copolymer glycidyl ester reacts chemically with the terminal carboxyl or hydroxyl groups of PBT resin through the epoxy functional groups in the molecular chain to form a grafted or cross-linked structure, thereby achieving precise control over the crystallization behavior of PBT resin.

[0014] Preferably, in the ternary copolymer glycidyl methacrylate, the weight content of glycidyl methacrylate unit is 5% to 15%, the weight content of ethylene unit is 60% to 75%, and the weight content of methyl acrylate unit is 20% to 30%; the chemical reaction can restrict the movement of PBT molecular chains but not completely inhibit their crystallization, so that the crystallinity of PBT 3D printing material is controlled at 25% to 40%.

[0015] Preferably, the intrinsic viscosity of the PBT resin is 0.9 to 1.0 dL / g; the antioxidant is composed of pentaerythritol tetrakis(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and tris(2,4-di-tert-butylphenyl)phosphite in a 1:2 ratio.

[0016] Preferably, the supercooling of the PBT 3D printing material is 40.6 to 45.7°C, the printing process window width is ≥25°C, and warp-free printing can be achieved within the printing platform temperature range of 55 to 90°C. Furthermore, the tensile strength of the printed product is ≥65MPa and the impact strength is ≥12kJ / m².

[0017] Preferably, the number average molecular weight of the ternary copolymer glycidyl ester is 10,000 to 30,000, and the molecular weight distribution index is 1.8 to 2.5. This molecular weight range can ensure its melt compatibility with PBT resin, while avoiding the decrease in processing fluidity caused by excessively high molecular weight, or the unstable crystallization control effect caused by excessively low molecular weight.

[0018] Preferably, the material further includes 0.5 to 2 parts of an inorganic modifier, wherein the inorganic modifier is nano-silica modified with silane coupling agent KH-550, with a particle size of 50 to 100 nm. It can work synergistically with ternary copolymer glycidyl ester to further refine PBT crystal particles, reduce crystallization shrinkage, and improve the heat resistance and dimensional stability of the material.

[0019] A method for preparing PBT 3D printing material, the method comprising the following steps:

[0020] S1. Drying: Vacuum dry the PBT resin at 100-120℃ for 4-6 hours to remove moisture;

[0021] S2. Premixing: Place the dried PBT resin, terpolymer glycidyl ester, antioxidant, optional other additives and optional inorganic modifiers into a high-speed mixer and mix for 5 to 10 minutes to obtain a premix.

[0022] S3. Melt Blending: The premixed material is fed into a twin-screw extruder with a length-to-diameter ratio of 40:1. The temperature of each section of the screw is controlled as follows: 220℃ in the feeding section, 230-240℃ in the homogenization section, and 250℃ in the die head. The screw speed is 200-400 rpm, and the vacuum degree is -0.06 to -0.08. After melt extrusion, cooling, stringing, and pelletizing, PBT 3D printing material masterbatch is obtained.

[0023] S4. Secondary drying: Dry the masterbatch obtained in step S3 at 80-100℃ for 3-5 hours for later use.

[0024] Preferably, step S2 premixing adopts a segmented gradient mixing mode, specifically: first, PBT resin and ternary copolymer glycidyl ester are mixed at 800-1000 rpm for 3-4 minutes, then antioxidants, inorganic modifiers and other additives are added, and the speed is adjusted to 1100-1200 rpm to continue mixing for 2-6 minutes; during the mixing process, the material temperature is controlled at 50-60℃ by jacket water cooling.

[0025] Preferably, the melt blending process adopts a segmented temperature-controlled reaction and dynamic heat preservation mode. Specifically, the segmented temperature-controlled reaction involves a gradient temperature increase from the feeding section to the homogenization section of 220℃→225℃→230℃→240℃, with a residence time of 4 to 5 minutes in the homogenization section, and a gradient cooling of 45℃→35℃→25℃ after the material is discharged from the die head.

[0026] Preferably, after the secondary drying in step S4, a pre-testing step for masterbatch performance is added. The test indicators are crystallinity 25%~40%, moisture content ≤0.05%, melt index 15~25g / 10min, and the test conditions are 230℃ / 2.16kg.

[0027] The technical effects and advantages of this invention are as follows:

[0028] This invention creatively introduces a ternary copolymer glycidyl ester with a specific composition and molecular weight as a crystallization regulator for PBT. The epoxy functional groups in its molecular chain chemically react with the terminal carboxyl or hydroxyl groups of PBT to form grafted or cross-linked structures, effectively restricting the movement of the PBT molecular chains without completely inhibiting crystallization. This precisely controls the final crystallinity of the material within a suitable range of 25%–40%, rather than simply increasing or decreasing it. Simultaneously, with the increase in the amount of ternary copolymer glycidyl ester added, the crystallization peak temperature of PBT significantly decreases, the supercooling increases to 40.6–45.7℃, and the crystallization rate slows down significantly, fundamentally reducing crystallization shrinkage and internal stress, and completely solving the core pain points of warping and deformation in PBT 3D printed products. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the preparation method of the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] This invention provides, for example Figure 1The PBT 3D printing material shown is composed of the following components by weight: 80-95 parts of PBT resin, 5-20 parts of ternary copolymer glycidyl ester, 0.1-1 parts of antioxidant, and 0-5 parts of optional other additives.

[0032] Other additives are one or two of lubricants and pigments, which can be selectively added according to actual printing needs;

[0033] Ternary copolymer glycidyl ester is a terpolymer of glycidyl methacrylate, ethylene, and methyl acrylate. The terpolymer glycidyl ester reacts chemically with the terminal carboxyl or hydroxyl groups of PBT resin through the epoxy functional groups in the molecular chain to form a grafted or cross-linked structure, thereby achieving precise control over the crystallization behavior of PBT resin.

[0034] Furthermore, in the ternary copolymer glycidyl methacrylate, the weight content of glycidyl methacrylate unit is 5% to 15%, the weight content of ethylene unit is 60% to 75%, and the weight content of methyl acrylate unit is 20% to 30%. The chemical reaction can restrict the movement of PBT molecular chains but does not completely inhibit their crystallization, so that the crystallinity of PBT 3D printing material can be controlled at 25% to 40%.

[0035] Furthermore, the intrinsic viscosity of PBT resin is 0.9–1.0 dL / g; the antioxidant is a compound of pentaerythritol tetrakis(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and tris(2,4-di-tert-butylphenyl)phosphite in a 1:2 ratio.

[0036] Furthermore, the supercooling of PBT 3D printing material is 40.6~45.7℃, the printing process window width is ≥25℃, and warp-free printing can be achieved within the printing platform temperature range of 55~90℃. The tensile strength of the printed products is ≥65MPa and the impact strength is ≥12kJ / m².

[0037] Furthermore, the number average molecular weight of the ternary copolymer glycidyl ester is 10,000 to 30,000, and the molecular weight distribution index is 1.8 to 2.5. This molecular weight range can ensure its melt compatibility with PBT resin, while avoiding the decrease in processing fluidity caused by excessively high molecular weight, or the unstable crystallization control effect caused by excessively low molecular weight.

[0038] Furthermore, it also includes 0.5 to 2 parts of inorganic modifier, which is nano-silica modified with silane coupling agent KH-550, with a particle size of 50 to 100 nm. It can work synergistically with ternary copolymer glycidyl ester to further refine PBT crystal particles, reduce crystallization shrinkage, and improve the heat resistance and dimensional stability of the material.

[0039] This invention creatively introduces a ternary copolymer glycidyl ester with a specific composition and molecular weight as a crystallization regulator for PBT. The epoxy functional groups in its molecular chain chemically react with the terminal carboxyl or hydroxyl groups of PBT to form grafted or cross-linked structures, effectively restricting the movement of the PBT molecular chains without completely inhibiting crystallization. This precisely controls the final crystallinity of the material within a suitable range of 25%–40%, rather than simply increasing or decreasing it. Simultaneously, with the increase in the amount of ternary copolymer glycidyl ester added, the crystallization peak temperature of PBT significantly decreases, the supercooling increases to 40.6–45.7℃, and the crystallization rate slows down significantly, fundamentally reducing crystallization shrinkage and internal stress, and completely solving the core pain points of warping and deformation in PBT 3D printed products.

[0040] Due to the slower crystallization rate, the melt has a longer amorphous state existence time after extrusion, providing a valuable time window for sufficient diffusion, entanglement, and bonding between printed layers and filaments. Compared to the less than 5°C process window of pure PBT, the printing process window width of the material of this invention is ≥25°C, enabling warp-free printing within a printing platform temperature range of 55–90°C. This significantly reduces sensitivity to printing parameters, substantially improves printing success rate and process stability, and lowers the technical requirements for operators.

[0041] The appropriate degree of crystallinity ensures the necessary rigidity, strength, and heat resistance of the material while avoiding excessive shrinkage and internal stress caused by overly high crystallinity, resulting in high dimensional accuracy and good performance stability of the printed products. Simultaneously, slow crystallization helps form a more perfect crystal structure, reducing internal defects and making the mechanical properties of the products more uniform and stable. Its tensile strength ≥65MPa and impact strength ≥12kJ / m² meet the requirements for engineering components. Furthermore, the optional addition of KH-550 modified nano-silica, synergistically with ternary copolymer glycidyl ester, further enhances the material's heat resistance and dimensional stability, broadening its application range.

[0042] The ethylene and methyl acrylate segments in this terpolymer exhibit certain compatibility with PBT, while the chemical reaction between the epoxy groups and PBT provides "in-situ compatibilization," avoiding phase separation problems that may occur with simple blending and improving the uniformity and stability of the material. Simultaneously, the copolymer itself possesses a certain degree of toughness, which can mitigate the brittleness of PBT to some extent, enhancing the impact resistance of printed products and achieving a balance between rigidity, toughness, and processability.

[0043] A method for preparing PBT 3D printing material, comprising the following steps:

[0044] S1. Drying: Vacuum dry the PBT resin at 100-120℃ for 4-6 hours to remove moisture;

[0045] S2. Premixing: Place the dried PBT resin, terpolymer glycidyl ester, antioxidant, optional other additives and optional inorganic modifiers into a high-speed mixer and mix for 5 to 10 minutes to obtain a premix.

[0046] S3. Melt Blending: The premixed material is fed into a twin-screw extruder with a length-to-diameter ratio of 40:1. The temperature of each section of the screw is controlled as follows: 220℃ in the feeding section, 230-240℃ in the homogenization section, and 250℃ in the die head. The screw speed is 200-400 rpm, and the vacuum degree is -0.06 to -0.08. After melt extrusion, cooling, stringing, and pelletizing, PBT 3D printing material masterbatch is obtained.

[0047] S4. Secondary drying: Dry the masterbatch obtained in step S3 at 80-100℃ for 3-5 hours for later use.

[0048] Furthermore, step S2 premixing adopts a segmented gradient mixing mode, specifically: first, PBT resin and ternary copolymer glycidyl ester are mixed at 800-1000 rpm for 3-4 minutes, then antioxidants, inorganic modifiers and other additives are added, and the speed is adjusted to 1100-1200 rpm to continue mixing for 2-6 minutes; during the mixing process, the material temperature is controlled at 50-60℃ by jacket water cooling.

[0049] Furthermore, the step melt blending adopts a segmented temperature-controlled reaction and dynamic heat preservation mode. Specifically, the segmented temperature-controlled reaction adopts a gradient temperature increase from the feeding section to the homogenization section of 220℃→225℃→230℃→240℃, the residence time in the homogenization section is 4 to 5 minutes, and the gradient cooling after the die head discharge is 45℃→35℃→25℃.

[0050] Furthermore, after the secondary drying in step S4, a pre-testing step for masterbatch performance is added. The test indicators are crystallinity 25%~40%, moisture content ≤0.05%, melt index 15~25g / 10min, and the test conditions are 230℃ / 2.16kg.

[0051] The preparation method of this invention adopts conventional high-speed mixing and twin-screw melt blending processes, which do not require special equipment. The process parameters are clear and highly controllable. Furthermore, through optimized design such as segmented gradient mixing and segmented temperature-controlled reaction, the stability and consistency of material properties are ensured, making it suitable for large-scale industrial production and showing good prospects for industrial applications.

[0052] The present invention will be further illustrated below with specific embodiments, but the present invention is not limited to the following embodiments. In the embodiments, the PBT resin is selected as a product with an intrinsic viscosity of 0.9-1.0 dL / g, the ternary copolymer glycidyl ester is selected as a product with a GMA content of 8wt%, an MA content of 28wt%, and the remainder being ethylene, with a number average molecular weight of 20,000 and a molecular weight distribution index of 2.0, the antioxidant is antioxidant 1010 and antioxidant 168 compounded in a 1:2 ratio, the inorganic modifier is nano-silica (particle size 80nm) modified by KH-550, the lubricant is butyl stearate, the pigment is titanium dioxide, antioxidant 1010 is pentaerythritol tetrakis β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and antioxidant 168 is tris(2,4-di-tert-butylphenyl) phosphite.

[0053] Components Comparative Example 1 Example 1 Example 2 Example 3 Example 4 PBT 100 92 88 82 80 Terpolymer 0 8 12 18 20 Antioxidant 1010 0.2 0.2 0.2 0.2 0.2 Antioxidant 168 0.4 0.4 0.4 0.4 0.4 Inorganic modifiers 0 0 1.0 1.5 2.0 lubricant 0 0.5 0.5 0.5 0.5

[0054] According to the preparation method of this invention, the components are dried, premixed, melt-blended, and dried again to obtain modified PBT material masterbatch. The premixing process is as follows: PBT resin and ternary copolymer glycidyl ester are mixed at 900 rpm for 3.5 minutes, then antioxidants, inorganic modifiers, and lubricants are added, and the speed is adjusted to 1150 rpm for another 4 minutes, with the material temperature controlled at 55°C during mixing. The melt-blending process is as follows: a twin-screw extruder with a length-to-diameter ratio of 40:1 is used; the temperature gradient from the feeding section to the homogenization section is 220°C → 225°C → 230°C → 240°C; the die head temperature is 250°C; the screw speed is 300 rpm; the vacuum degree is -0.07; the residence time in the homogenization section is 4.5 minutes; and the material is gradually cooled after exiting the die head at 45°C → 35°C → 25°C. The drying process is as follows: PBT resin is vacuum-dried at 110°C for 5 hours, and the masterbatch is dried at 90°C for 4 hours.

[0055] The obtained masterbatch was drawn into filaments using a single-screw extruder to produce FDM printing filaments with a diameter of 1.75 mm, which were then used for subsequent performance testing and printing verification.

[0056] The performance testing and print verification are detailed below:

[0057] The performance of the filaments obtained in Examples 1-4 and Comparative Example 1 was tested. The test items and methods are as follows:

[0058] DSC test: The crystallization behavior of the material was tested using a differential scanning calorimeter. The test conditions were: heating rate 10℃ / min, cooling rate 10℃ / min, nitrogen atmosphere, and the melting point was recorded. Crystallization peak temperature Calculate the subcooling .

[0059] Crystallinity calculation: Crystallinity .in To measure the enthalpy of fusion, The enthalpy of fusion of pure PBT perfect crystals (taken as 142 J / g). This represents the weight fraction of PBT in the composite material.

[0060] Melt flow index test: The melt flow index of the material was tested according to GB / T3682-2018 standard at 230℃ and 2.16kg.

[0061] Mechanical property testing: Tensile strength was tested according to GB / T1040-2018 standard, and impact strength was tested according to GB / T1843-2008 standard.

[0062] Printing Test: Using the same FDM 3D printer, print a single-walled rectangular strip measuring 60mm × 20mm × 10mm to visually assess warping. Start with a printing platform temperature of 50℃ and increase in 5℃ increments until the lowest platform temperature is found that allows for successful, warp-free printing. Record this "lowest successful platform temperature" and the "printing process window width" (the temperature range for successful printing). Simultaneously observe the appearance of the printed strip to assess the degree of warping.

[0063] The test results are shown in the table below:

[0064] project Comparative Example 1 Example 1 Example 2 Example 3 Example 4 DSC results - - - - - Melting point (°C) 224.5 223.1 222.8 221.5 221.2 Crystallization peak temperature (°C) 191.2 182.5 179.3 175.8 174.6 supercooling 33.3 40.6 43.5 45.7 46.6 Crystallinity (%) 38.5 34.2 31.0 27.8 26.5 Melt index (g / 10min) 18.2 19.5 20.3 22.1 24.5 Mechanical properties - - - - - Tensile strength (MPa) 68.5 67.2 66.8 65.5 65.1 Impact strength (kJ / m²) 8.2 12.5 13.8 14.2 14.5 Print test - - - - - Minimum successful platform temperature (°C) 85 65 60 55 55 Process window width (°C) <5(85-90) 25(65-90+) 30(60-90+) 35(55-90+) 35(55-90+) warping of printed splines serious none none none none

[0065] The test results in the table above show that:

[0066] Significantly improved crystallization behavior regulation: With increasing addition of ternary copolymer glycidyl ester, the crystallization peak temperature of PBT decreased. Significantly reduced, undercooling The temperature increased significantly, from 33.3°C in Comparative Example 1 to 46.6°C in Example 4, demonstrating that the crystallization process was effectively delayed and the crystallization rate was slowed down; simultaneously, the crystallinity of the material increased. As the amount added increased, the concentration gradually decreased from 38.5% to 26.5%, achieving effective and continuous control of crystallinity, and keeping it within the preset range of 25% to 40%, thus achieving the goal of precise control.

[0067] The melt flow index of Examples 1-4 is in the range of 15-25 g / 10 min, which is suitable for the extrusion requirements of FDM printing. At the same time, the printing process window width is ≥25℃, and the minimum success plateau temperature is reduced to 55-65℃. Compared with Comparative Example 1 (process window <5℃, minimum success plateau temperature 85℃), the process adaptability is greatly improved, and stable printing can be achieved in a wide temperature range, significantly reducing the printing difficulty.

[0068] The tensile strength of Examples 1-4 is ≥65MPa and the impact strength is ≥12kJ / m². Compared with Comparative Example 1 (impact strength only 8.2kJ / m²), the impact resistance is significantly improved, achieving a balance between rigidity and toughness. Meanwhile, Examples 2-4 with added inorganic modifiers show further improvement in mechanical properties and dimensional stability compared with Example 1, proving that the KH-550 modified nano-silica and ternary copolymer glycidyl ester have a good synergistic effect, which can further optimize the material properties.

[0069] The printed template of Comparative Example 1 was severely warped and could not meet the usage requirements; while the printed templates of Examples 1-4 were all flat, without visible warping, and had high dimensional accuracy, completely solving the problem of warping in PBT3D printing and meeting the printing needs of high-precision engineering parts.

[0070] In summary, this invention successfully achieved precise control over the crystallinity and crystallization kinetics of PBT through ternary copolymer glycidyl ester with specific composition and molecular weight. Furthermore, the optional addition of KH-550-modified nano-silica further optimizes the performance. The resulting 3D printing material exhibits excellent warpage resistance, a wide process window, and good comprehensive mechanical properties. Its preparation process is simple and controllable, suitable for industrial production, and highly suitable for manufacturing high-quality, high-precision engineering parts using FDM technology, demonstrating broad industrial application prospects.

[0071] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A PBT 3D printing material, characterized in that, By weight, it consists of the following components: 80-95 parts of PBT resin, 5-20 parts of terpolymer glycidyl ester, 0.1-1 parts of antioxidant, and 0-5 parts of optional other additives; The other additives are one or two of lubricants and pigments; The ternary copolymer glycidyl ester is a ternary copolymer of glycidyl methacrylate, ethylene and methyl acrylate, and the ternary copolymer glycidyl ester forms a grafted or cross-linked structure by chemically reacting the epoxy functional groups in the molecular chain with the terminal carboxyl groups or terminal hydroxyl groups of PBT resin.

2. The PBT 3D printing material according to claim 1, characterized in that, In the ternary copolymer glycidyl methacrylate, the weight content of glycidyl methacrylate unit is 5% to 15%, the weight content of ethylene unit is 60% to 75%, and the weight content of methyl acrylate unit is 20% to 30%. The chemical reaction can restrict the movement of PBT molecular chains but not completely inhibit their crystallization, so that the crystallinity of PBT 3D printing material is controlled at 25% to 40%.

3. The PBT 3D printing material according to claim 1, characterized in that, The intrinsic viscosity of the PBT resin is 0.9-1.0 dL / g; the antioxidant is composed of pentaerythritol tetrakis(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and tris(2,4-di-tert-butylphenyl)phosphite in a 1:2 ratio.

4. The PBT 3D printing material according to claim 1, characterized in that, The PBT 3D printing material has a supercooling of 40.6 to 45.7°C and a printing process window width of ≥25°C. It can achieve warp-free printing within a printing platform temperature range of 55 to 90°C, and the printed products have a tensile strength of ≥65MPa and an impact strength of ≥12kJ / m².

5. The PBT 3D printing material according to claim 1, characterized in that, The ternary copolymer glycidyl ester has a number-average molecular weight of 10,000 to 30,000 and a molecular weight distribution index of 1.8 to 2.

5.

6. The PBT 3D printing material according to claim 1, characterized in that, It also includes 0.5 to 2 parts of an inorganic modifier, which is nano-silica modified with silane coupling agent KH-550, with a particle size of 50 to 100 nm, and can synergistically work with ternary copolymer glycidyl ester.

7. A method for preparing a PBT 3D printing material, used to prepare the PBT 3D printing material according to any one of claims 1-6, characterized in that, The preparation method includes the following steps: S1. Drying: Vacuum dry the PBT resin at 100-120℃ for 4-6 hours to remove moisture; S2. Premixing: Place the dried PBT resin, terpolymer glycidyl ester, antioxidant, optional other additives and optional inorganic modifiers into a high-speed mixer and mix for 5 to 10 minutes to obtain a premix. S3. Melt Blending: The premixed material is fed into a twin-screw extruder with a length-to-diameter ratio of 40:

1. The temperature of each section of the screw is controlled as follows: 220℃ in the feeding section, 230-240℃ in the homogenization section, and 250℃ in the die head. The screw speed is 200-400 rpm, and the vacuum degree is -0.06 to -0.

08. After melt extrusion, cooling, stringing, and pelletizing, PBT 3D printing material masterbatch is obtained. S4. Secondary drying: Dry the masterbatch obtained in step S3 at 80-100℃ for 3-5 hours for later use.

8. The method for preparing a PBT 3D printing material according to claim 7, characterized in that, Step S2 premixing adopts a segmented gradient mixing mode, specifically: first, PBT resin and ternary copolymer glycidyl ester are mixed at 800-1000 rpm for 3-4 minutes, then antioxidants, inorganic modifiers and other additives are added, and the speed is adjusted to 1100-1200 rpm to continue mixing for 2-6 minutes; during the mixing process, the material temperature is controlled at 50-60℃ by jacket water cooling.

9. The method for preparing a PBT 3D printing material according to claim 7, characterized in that, The melt blending process adopts a segmented temperature-controlled reaction and dynamic heat preservation mode. Specifically, the segmented temperature-controlled reaction involves a gradient temperature increase from the feeding section to the homogenization section of 220℃→225℃→230℃→240℃, with a residence time of 4 to 5 minutes in the homogenization section. After the material exits from the die head, a gradient cooling process of 45℃→35℃→25℃ is adopted.

10. The method for preparing a PBT 3D printing material according to claim 7, characterized in that, After the secondary drying in step S4, a pre-testing step for masterbatch performance is added. The test indicators are crystallinity 25%~40%, moisture content ≤0.05%, melt index 15~25g / 10min, and the test conditions are 230℃ / 2.16kg.

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