A 3D printing wire based on special PVC resin and a preparation method thereof

Abstract

The application discloses a kind of 3D printing wire based on special PVC resin and preparation method thereof, belong to 3D printing wire preparation technical field, including the following steps: raw material grading premix cooling treatment, subsection temperature control single screw extrusion granulation, low shear constant temperature wire drawing extrusion molding, three-stage gradient constant temperature cooling shaping, traction diameter measurement and constant tension winding, the application adopts MG-8 and SG-3 special PVC resin compound special auxiliary system, on the premise of guaranteeing printing smooth, not easy to plug, greatly improve the heat resistance, wear resistance, flame retardant, acid and alkali resistance, weather resistance and mechanical strength of wire, effectively solve the existing PLA consumables poor heat resistance, low temperature brittle, outdoor easy to age and powder, and ABS consumables shrinkage rate is high, large printing warping layering, melt release large VOC industry pain points;The application adopts two-stage gradient mixing and negative pressure dust removal, auxiliary agent dispersion is uniform, eradicates dust cause;Underwater pelletizing and condensation drying strictly control the moisture content of masterbatch, eliminate wire porosity.

Description

Technical Field

[0001] This invention belongs to the field of 3D printing filament preparation technology, specifically relating to a 3D printing filament based on special PVC resin and its preparation method. Background Technology

[0002] Currently, the mainstream consumables in the FDM (Fused Deposition Modeling) 3D printing industry are mainly PLA and ABS polymer filaments. These two types of materials have mature industrial chains and are easy to procure, but their inherent defects are prominent and they are difficult to meet the long-term use needs of industrial functional parts.

[0003] PLA material has low molding shrinkage and is easy to print, but its heat resistance is only 60℃, making it prone to softening and deformation in high-temperature environments, and significant brittleness in low-temperature conditions. Long-term outdoor placement can lead to hydrolysis, aging, and powdering, limiting its application to static decorative models and making it unsuitable for load-bearing applications. It also lacks flame retardant and acid / alkali resistance. ABS material has good toughness and is suitable for simple industrial prototyping, but its high molding shrinkage makes it prone to warping and delamination in large-sized workpieces. Processing requires a fully enclosed machine and high-temperature heated bed, resulting in high equipment costs. The high-temperature melting process releases large amounts of irritating VOC gases, making it environmentally unfriendly. Summary of the Invention

[0004] To address the problems mentioned in the background section, this invention provides a 3D printing filament based on a special PVC resin and its preparation method, which features excellent thermal stability, low volatility, flame retardancy, and abrasion resistance.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a 3D printing filament based on special PVC resin, characterized in that it is composed of the following raw materials by weight percentage: 33% special modified PVC resin, 58% DOTP plasticizer, 4% calcium-zinc stabilizer, 1% polyethylene wax internal lubricant, 0.5% polyethylene wax external lubricant, and 3.5% acrylic processing aids; The special modified PVC resin is uniformly compounded from 82% by weight of bulk MG-8 PVC resin and 18% by weight of suspension SG-3 PVC resin.

[0006] Furthermore, in this invention, a method for preparing 3D printing filament based on special PVC resin as described in claim 1 is characterized by comprising the following steps: S1. Raw material grading, premixing, and cooling treatment: Accurately weigh all raw materials according to the formula ratio and put them into a closed high-speed mixer. Mix the materials in two stages with gradient heating. In the first stage, heat the material to 80°C and stir for 10 minutes to allow the DOTP plasticizer to fully impregnate and coat the special modified PVC resin particles. In the second stage, heat the material to 110°C and stir continuously for 8 minutes to achieve uniform fusion of various additives and resin. After mixing, quickly unload the material into a cooling mixer and continue air cooling to obtain a dry mix with no agglomeration and uniform composition. S2. Segmented Temperature-Controlled Single-Screw Extrusion Granulation: The cooled dry mixture is fed into a single-screw granulation extruder. The extruder has five sections of barrel with independent temperature control: Zone 1 155℃, Zone 2 159℃, Zone 3 165℃, Zone 4 175℃, and Zone 5 180℃. The molten material is extruded through a strip die and then fed into an underwater pelletizer to be cut into cylindrical PVC masterbatches. The masterbatches are then conveyed to a hot air drying equipment for constant temperature drying. S3. Low-shear constant temperature wire drawing extrusion molding: The dried PVC masterbatch is fed into a single screw extruder for wire drawing. The temperature range of the entire barrel of the wire drawing machine is strictly controlled between 150 and 178°C. The die head is a low-flow-resistance circular wire drawing die. The die hole size matches the standard specifications of the finished wire. The melt is extruded at a uniform speed to form a continuous wire blank. S4. Three-stage gradient constant temperature cooling and shaping: The continuous filament extruded from the die head passes through three independent cooling water tanks in sequence without interruption. The first-stage warm water tank has a constant water temperature of 45℃, which is used for preliminary shaping and releasing internal stress of the melt; the second-stage room temperature clear water tank has a constant water temperature of 25℃, which quickly removes a large amount of heat from the surface of the continuous filament; the third-stage low temperature water cooling tank has a constant water temperature of 10℃, which allows the continuous filament to be completely solidified and formed into a 3D printing filament based on special PVC resin, eliminating bending, thickness deviation and deformation of the 3D printing filament based on special PVC resin. S5. Traction Diameter Measurement and Constant Tension Winding: After cooling and shaping, the 3D printing filament based on special PVC resin is pulled at a constant speed by a frequency conversion traction machine. A laser diameter online detector is installed in the middle of the traction conveying path to collect the diameter data of the 3D printing filament based on special PVC resin in real time. The detector, the extruder screw, and the traction machine motor form a closed-loop control system. When the diameter of the 3D printing filament based on special PVC resin exceeds the tolerance range, the screw speed and traction speed are automatically fine-tuned. After diameter calibration, the tension of the filament is adjusted by a tension buffer mechanism and finally neatly wound into a standard plastic tray to obtain the finished 3D printing filament based on special PVC resin.

[0007] Furthermore, in the present invention, the high-speed mixer in step S1 is equipped with a negative pressure dust removal and recovery device.

[0008] Furthermore, in this invention, the barrels of the granulation extruder in step S2 and the wire drawing extruder in step S3 are both wrapped with an integrated circulating water cooling jacket.

[0009] Furthermore, in the present invention, a static mixer is built into the feed front end of the wire drawing die in step S3.

[0010] Furthermore, in this invention, the winding station in S5 is equipped with a high-voltage electrostatic eliminator.

[0011] Furthermore, in this invention, each of the three cooling water tanks in step S4 is equipped with an independent constant temperature circulating temperature control unit.

[0012] Furthermore, in the present invention, in step S5, multiple sets of adjustable tension buffer mechanisms are provided between the traction machine and the end winding machine.

[0013] Furthermore, in this invention, the hot air drying process in step S2 is equipped with a closed hot air circulation system and a water vapor condensation and recovery device.

[0014] Furthermore, in step S3, a wind-cooled auxiliary cooling ring is provided on the outside of the wire drawing die.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention uses a special PVC resin compounded with MG-8 and SG-3, combined with a special additive system. While ensuring smooth printing and preventing clogging, it significantly improves the heat resistance, wear resistance, flame retardancy, acid and alkali resistance, weather resistance, and mechanical strength of the filament. It effectively solves the industry pain points of existing PLA consumables, such as poor heat resistance, brittleness at low temperatures, and easy aging and powdering outdoors, as well as the high shrinkage rate of ABS consumables, warping and delamination of large printed parts, and the release of a large amount of VOCs during melting. 2. This invention employs a two-stage gradient mixing process and negative pressure dust removal, ensuring uniform dispersion of additives and eliminating dust-causing factors. Underwater pelletizing and condensation drying strictly control the moisture content of the masterbatch, eliminating porosity in the wire. A static mixer homogenizes the melt, and air cooling of the die stabilizes the initial diameter, significantly reducing diameter tolerance. Three-stage independent constant temperature gradient water baths release molding stress step by step, resulting in straight, bend-free wire with a regular cross-section. Online laser closed-loop diameter measurement and dynamic parameter adjustment, combined with constant tension buffering and electrostatic elimination winding, ensure that the finished product has no thickness deviation, stretching thinning, wrinkles, or surface pitting, meeting industrial 3D printing standards and significantly improving the yield rate. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the preparation process of the present invention; Detailed Implementation

[0017] 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.

[0018] This invention provides the following technical solution: a 3D printing filament based on special PVC resin, composed of the following raw materials by weight percentage: 33% special modified PVC resin, 58% DOTP plasticizer, 4% calcium-zinc stabilizer, 1% polyethylene wax internal lubricant, 0.5% polyethylene wax external lubricant, and 3.5% acrylic processing aids; The special modified PVC resin is a uniform compound of 82% by weight of bulk MG-8 PVC resin and 18% by weight of suspension SG-3 PVC resin.

[0019] MG-8 PVC resin has a moderate molecular weight and good melt flow, making it suitable for low-speed extrusion in 3D printing; SG-3 PVC resin has excellent rigidity and heat resistance, and the combination of the two balances the smoothness of filament printing and the mechanical strength of the finished product; DOTP environmentally friendly plasticizer combined with calcium and zinc stabilizer prevents heavy metal precipitation and results in low volatility during high-temperature extrusion; the internal and external compounded polyethylene wax takes into account both internal plasticization and lubrication as well as demolding effect, and acrylate processing aid improves melt extensibility, ensuring that filament printing does not clog and has strong interlayer adhesion.

[0020] Please see Figure 1 A method for preparing 3D printing filaments based on special PVC resin includes the following steps: S1. Raw Material Grading, Premixing, and Cooling Treatment: Accurately weigh all raw materials according to the formula ratio and put them into a closed high-speed mixer. Mix the materials in two stages with gradient heating and stirring. In the first stage, heat the material to 80°C and stir for 10 minutes to allow the DOTP plasticizer to fully impregnate and coat the special modified PVC resin. In the second stage, heat the material to 110°C and stir continuously for 8 minutes to achieve uniform fusion of various additives and resin. After mixing, quickly unload the material into a cooling mixer and continuously air-cool it to obtain a dry mixture without agglomeration and with uniform components. In the low-temperature stage, the liquid DOTP is first allowed to fully impregnate the resin particles to avoid additive clumping. In the high-temperature stage, various additives are evenly dispersed to solve the problem of uneven distribution of additives in traditional single-stage mixing, which causes uneven wire hardness and filament breakage during printing. After mixing, air-cooling is performed to quickly cool the high-temperature mixture, preventing the PVC from being slightly degraded due to premature heating, and avoiding the accumulation and clumping of hot material to ensure uniform and stable feeding for subsequent granulation.

[0021] S2. Segmented Temperature-Controlled Single-Screw Extrusion Granulation: The cooled dry mixture is fed into a single-screw granulator extruder. The extruder has five independently temperature-controlled sections: Zone 1 155℃, Zone 2 159℃, Zone 3 165℃, Zone 4 175℃, and Zone 5 180℃. The molten material is extruded through a strip die and then fed into an underwater pelletizer. The melt is rapidly cooled in water, resulting in well-shaped, non-adhesive pellets with uniform particle size. The pellets are then cut into cylindrical PVC masterbatches. The PVC masterbatches are then conveyed to a hot air drying unit for constant-temperature drying. The low-temperature section slowly plasticizes the material, while the high-temperature section fully melts it, preventing local overheating that could lead to PVC decomposition and the release of hydrogen chloride, thus improving the material's thermal stability.

[0022] S3. Low-shear constant temperature wire drawing extrusion molding: The dried PVC masterbatch is fed into a single screw extruder for wire drawing. The temperature range of the entire barrel of the wire drawing machine is strictly controlled between 150 and 178°C. The die head is a low-flow-resistance circular wire drawing die. The die hole size matches the standard specifications of the finished wire. The melt is extruded at a uniform speed to form a continuous wire blank. S4. Three-stage gradient constant temperature cooling and shaping: The continuous filament extruded from the die head passes through three independent cooling water tanks in sequence without interruption. The first-stage warm water tank has a constant water temperature of 45℃, which is used for preliminary shaping and releasing internal stress of the melt; the second-stage room temperature clear water tank has a constant water temperature of 25℃, which quickly removes a large amount of heat from the surface of the continuous filament; the third-stage low temperature water cooling tank has a constant water temperature of 10℃, which allows the continuous filament to be completely solidified and formed into a 3D printing filament based on special PVC resin, eliminating bending, thickness deviation and deformation of the 3D printing filament based on special PVC resin. S5. Traction Diameter Measurement and Constant Tension Winding: After cooling and shaping, the 3D printing filament based on special PVC resin is pulled at a constant speed by a frequency conversion traction machine. A laser diameter online detector is installed in the middle of the traction conveying path to collect the diameter data of the 3D printing filament based on special PVC resin in real time. The detector, the extruder screw, and the traction machine motor form a closed-loop control system. When the diameter of the 3D printing filament based on special PVC resin exceeds the tolerance range, the screw speed and traction speed are automatically fine-tuned. After diameter calibration, the tension of the filament is adjusted by a tension buffer mechanism and finally neatly wound into a standard plastic tray to obtain the finished 3D printing filament based on special PVC resin.

[0023] In step S1, the high-speed mixer is equipped with a negative pressure dust collection and recovery device, which extracts fine dust from the raw materials in real time, preventing dust from mixing into the materials and eliminating internal air bubbles and surface pits in the wire from the source, thereby improving the appearance and density of the wire.

[0024] Both the granulation extruder in step S2 and the fiber extruder in step S3 have an integrated circulating water-cooled jacket wrapped around their barrels. Circulating cooling water is continuously supplied to the jacket to remove excess heat from the barrel wall in real time, thereby inhibiting the high-temperature decomposition of PVC materials and the release of hydrogen chloride gas, and reducing the odor and corrosive volatiles in the wire.

[0025] In step S3, a static mixer is built into the front end of the wire drawing die, and multiple layers of baffles continuously divide and merge the melt, improving the overall uniformity of the PVC melt and significantly reducing the diameter fluctuation tolerance of the finished wire.

[0026] The S5 winding station is equipped with a high-voltage static eliminator to continuously neutralize the surface static electricity accumulated during wire extrusion and traction.

[0027] Each of the three cooling water tanks in step S4 is equipped with an independent constant temperature circulation temperature control unit. The water temperature of each tank is independently controlled in a closed loop to avoid mutual interference between the water temperatures of each tank, stabilize the gradient cooling and shaping effect of the wire, and improve the dimensional consistency of the wire.

[0028] In step S5, multiple adjustable tension buffer mechanisms are set between the traction machine and the end winding machine to buffer the fluctuations in traction speed in real time, maintain constant tensile tension of the wire throughout the process, and ensure that the wire wound on the spool is uniformly tight, without stretching or thinning, and without loosening or wrinkling.

[0029] In step S2, the hot air drying process is equipped with a closed hot air circulation system and a water vapor condensation and recovery device to quickly remove free moisture from the surface of the masterbatch and significantly reduce the internal porosity of the finished wire. The volatile water vapor is uniformly condensed and recovered to reduce workshop humidity and dust pollution and improve the production environment.

[0030] In step S3, an air-cooled auxiliary cooling ring is provided on the outside of the drawing die head. Low-temperature clean air is sprayed synchronously when the wire blank just leaves the die hole to assist in the initial cooling, reduce the high-temperature flow deformation of the wire blank before entering the first-stage water tank, and further stabilize the initial outer diameter of the wire.

[0031] The working principle and usage process of this invention: This invention uses a special PVC resin compounded from bulk MG-8 and suspension SG-3 as the base material, combined with DOTP environmentally friendly plasticizer, calcium-zinc stabilizer, internal and external lubrication system and acrylate processing aid to construct a special raw material system suitable for FDM printing, which solves various problems of traditional PVC processing such as easy decomposition, large fluctuation of wire size, many surface and internal defects, and poor printing performance.

[0032] Firstly, in the raw material pretreatment stage, all the precisely proportioned raw materials are fed into a closed high-speed mixer equipped with a negative pressure dust removal device. A two-stage gradient heating and stirring mode is adopted. In the low-temperature range, the two compounded PVC resins are fully impregnated by DOTP liquid plasticizer to prevent the additives from clumping and separating. Then, the temperature is increased to complete the deep fusion of all additives and resins, and the fine dust of the raw materials is removed simultaneously. After the mixing is completed, the material is immediately cooled by air cooling. This not only prevents the PVC from being prematurely slightly degraded due to high temperature accumulation, but also obtains a uniform dry-mixed powder without agglomeration or impurities. This avoids defects such as air bubbles and surface pits in the wire caused by dust from the source, laying a material foundation for subsequent stable extrusion.

[0033] The material then enters a segmented temperature-controlled granulation process. The uniformly dry-mixed material is fed into a single-screw granulator equipped with an integrated circulating water cooling jacket. It is slowly plasticized and melted according to a five-stage gradient heating curve of 155-180℃. The circulating cooling water on the cylinder wall continuously removes excess heat to prevent local overheating of the material from causing thermal degradation of PVC and the release of corrosive hydrogen chloride gas. After the molten material is extruded through a strip die, it is immediately cut and shaped underwater to obtain regular, non-adhesive cylindrical masterbatch. It is then sent to a drying device with a closed hot air circulation and water vapor condensation recovery to completely remove the free moisture from the particles, minimizing the probability of internal pores in the finished wire. The dried masterbatch is used as a special raw material for wire drawing, ensuring continuous and stable feeding for wire drawing and extrusion.

[0034] The dried masterbatch is conveyed to a single-screw extruder with a water-cooled cooling jacket. The whole machine maintains a low-shear constant temperature range of 150-178℃ to reduce the thermal degradation of the material. Before entering the die, the melt flows through a static mixer with built-in multi-layer baffles. Through repeated division and merging, the melt composition is highly uniform, reducing the fluctuation of wire diameter. The outside of the die is equipped with an air-cooled auxiliary cooling ring. Low-temperature clean air is sprayed immediately after the wire blank is extruded to pre-cool it, constrain the flow and deformation of the high-temperature melt, stabilize the initial outer diameter of the wire blank, and obtain a continuous wire blank.

[0035] The continuous filament blank flows uninterruptedly through three independently controlled gradient cooling water tanks. First, it passes through a 45°C warm water tank to slowly release the internal stress of the melt forming process, preventing the 3D printing filament based on special PVC resin from bending and warping later. Then, it passes through a 25°C ambient temperature water tank to quickly remove most of the heat and complete the solidification of the main body. Finally, it enters a 10°C low temperature water tank to achieve complete hardening and shaping. The three water temperatures do not interfere with each other, and the graded curing ensures that the 3D printing filament based on special PVC resin has a regular cross-section and no thickness deviation, completely solving the problems of stress residue and filament deformation caused by the rapid cooling of single-stage water cooling.

[0036] After cooling and setting, the rigid 3D printing filament based on special PVC resin enters the final traction and winding section. The outer diameter data of the 3D printing filament based on special PVC resin is collected in real time by a laser online diameter detector. The detector, together with the extruder screw and the variable frequency traction motor, forms a closed-loop system. When the size of the 3D printing filament based on special PVC resin exceeds the tolerance, the output and traction speeds are automatically and synchronously adjusted to achieve dynamic size correction. Multiple tension buffer mechanisms are set between the traction machine and the winding equipment to continuously offset the fluctuation of traction speed and maintain constant tensile tension throughout the process, preventing the 3D printing filament based on special PVC resin from becoming thinner or loose and wrinkled. The winding station is equipped with a high-voltage electrostatic eliminator to neutralize the surface static electricity generated by the friction of the 3D printing filament based on special PVC resin, preventing static electricity from attracting dust and the filament from tangling and knotting. Finally, a finished 3D printing filament based on special PVC resin with accurate dimensions, a smooth surface, and neat winding is obtained.

[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A 3D printing filament based on a special PVC resin, characterized in that: It is composed of the following raw materials by weight percentage: 33% special modified PVC resin, 58% DOTP plasticizer, 4% calcium-zinc stabilizer, 1% polyethylene wax internal lubricant, 0.5% polyethylene wax external lubricant, and 3.5% acrylic processing aids; The special modified PVC resin is uniformly compounded from 82% by weight of bulk MG-8 PVC resin and 18% by weight of suspension SG-3 PVC resin.

2. A method for preparing 3D printing filament based on special PVC resin as described in claim 1, characterized in that: Includes the following steps: S1. Raw material grading, premixing, and cooling treatment: Accurately weigh all raw materials according to the formula ratio and put them into a closed high-speed mixer. Mix the materials in two stages with gradient heating and stirring. In the first stage, heat the material to 80°C and stir for 10 minutes to allow the DOTP plasticizer to fully impregnate and coat the special modified PVC resin. In the second stage, heat the material to 110°C and stir continuously for 8 minutes to achieve uniform fusion of various additives and resin. After mixing, quickly unload the material into a cooling mixer and continuously air-cool it to obtain a dry mix with no agglomeration and uniform composition. S2. Segmented Temperature-Controlled Single-Screw Extrusion Granulation: The cooled dry mixture is fed into a single-screw granulation extruder. The extruder has five sections of barrel with independent temperature control: Zone 1 155℃, Zone 2 159℃, Zone 3 165℃, Zone 4 175℃, and Zone 5 180℃. The molten material is extruded through a strip die and then fed into an underwater pelletizer to be cut into cylindrical PVC masterbatches. The PVC masterbatches are then conveyed to a hot air drying equipment for constant temperature drying. S3. Low-shear constant temperature wire drawing extrusion molding: The dried PVC masterbatch is fed into a single screw extruder for wire drawing. The temperature range of the entire barrel of the wire drawing machine is strictly controlled between 150 and 178°C. The die head is a low-flow-resistance circular wire drawing die. The die hole size matches the standard specifications of the finished wire. The melt is extruded at a uniform speed to form a continuous wire blank. S4. Three-stage gradient constant temperature cooling and shaping: The continuous filament extruded from the die head passes through three independent cooling water tanks in sequence without interruption. The first-stage warm water tank has a constant water temperature of 45℃, which is used for preliminary shaping and releasing internal stress of the melt; the second-stage room temperature clear water tank has a constant water temperature of 25℃, which quickly removes a large amount of heat from the surface of the continuous filament; the third-stage low temperature water cooling tank has a constant water temperature of 10℃, which allows the continuous filament to be completely solidified and formed into a 3D printing filament based on special PVC resin, eliminating bending, thickness deviation and deformation of the 3D printing filament based on special PVC resin. S5. Traction Diameter Measurement and Constant Tension Winding: After cooling and shaping, the 3D printing filament based on special PVC resin is pulled at a constant speed by a frequency conversion traction machine. A laser diameter online detector is installed in the middle of the traction conveying path to collect the diameter data of the 3D printing filament based on special PVC resin in real time. The detector, the extruder screw, and the traction machine motor form a closed-loop control system. When the diameter of the 3D printing filament based on special PVC resin exceeds the tolerance range, the screw speed and traction speed are automatically fine-tuned. After diameter calibration, the tension of the filament is adjusted by a tension buffer mechanism and finally neatly wound into a standard plastic tray to obtain the finished 3D printing filament based on special PVC resin.

3. The method for preparing 3D printing filament based on special PVC resin according to claim 2, characterized in that: In step S1, the high-speed mixer is equipped with a negative pressure dust removal and recovery device.

4. The method for preparing 3D printing filament based on special PVC resin according to claim 2, characterized in that: The barrels of the granulation extruder in step S2 and the wire drawing extruder in step S3 are both wrapped with an integrated circulating water-cooled jacket.

5. The method for preparing 3D printing filament based on special PVC resin according to claim 2, characterized in that: In step S3, a static mixer is built into the feed front end of the wire drawing die.

6. The method for preparing 3D printing filament based on special PVC resin according to claim 2, characterized in that: The S5 winding station is equipped with a high-voltage electrostatic eliminator.

7. The method for preparing 3D printing filament based on special PVC resin according to claim 2, characterized in that: Each of the three cooling water tanks in step S4 is equipped with an independent constant temperature circulating temperature control unit.

8. The method for preparing 3D printing filament based on special PVC resin according to claim 2, characterized in that: In step S5, multiple adjustable tension buffer mechanisms are installed between the traction machine and the end winding machine.

9. The method for preparing 3D printing filament based on special PVC resin according to claim 2, characterized in that: The hot air drying process in step S2 is equipped with a closed hot air circulation system and a water vapor condensation and recovery device.

10. The method for preparing 3D printing filament based on special PVC resin according to claim 2, characterized in that: In step S3, a wind-cooled auxiliary cooling ring is fitted to the outside of the wire drawing die.

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