Search

CN-121973440-A - Thermoplastic polymer 3D printing wire rod containing liquid and semi-solid functional core layer and coaxial co-extrusion preparation process thereof

CN121973440ACN 121973440 ACN121973440 ACN 121973440ACN-121973440-A

Abstract

The application discloses a thermoplastic polymer 3D printing wire rod containing a liquid and semisolid functional core layer and a coaxial coextrusion preparation process thereof, which are of a coaxial core-shell structure and comprise an outer thermoplastic polymer thin-wall tube and an inner liquid and semisolid functional core layer from outside to inside. The coaxial core-shell structure formed by the outer thermoplastic polymer thin-wall tube and the inner liquid and semi-solid functional core layer breaks through the single functional limitation that the traditional FDM consumable material can only realize structural molding, and can endow a printed part with various special functions such as ultra-soft touch, self-repairing, electric conduction, high water absorbability, responsiveness and the like by selecting different core layer materials, so that the use requirements of scenes such as soft robots, medical consumables, electronic devices, self-repairing structural parts and the like are effectively met, meanwhile, the finished wire can be directly matched with the traditional FDM printer without any transformation on equipment, the application threshold of the functional 3D printing technology is greatly reduced, and the application boundary of the FDM technology is widened.

Inventors

  • ZHANG WENYI
  • ZHOU JIYAO

Assignees

  • 芜湖市爱三迪电子科技有限公司

Dates

Publication Date
20260505
Application Date
20260119

Claims (10)

  1. 1. The thermoplastic polymer 3D printing wire rod containing the liquid and semisolid functional core layer is characterized by being of a coaxial core-shell structure and comprising an outer thermoplastic polymer thin-wall tube and an inner liquid and semisolid functional core layer from outside to inside; The material of the outer layer thermoplastic polymer thin-wall pipe is one or a plurality of blends selected from PLA, ABS, PETG, nylon, TPU and EVA, the wall thickness of the outer layer thermoplastic polymer thin-wall pipe is 0.3-0.5mm, the ratio of the wall thickness of the outer layer thermoplastic polymer thin-wall pipe to the wire radius is 0.15-0.3, and the wire outer diameter of the outer layer thermoplastic polymer thin-wall pipe is 1.75mm or 2.85mm; The inner liquid and semisolid functional core layer is selected from one or a mixture of solidified resins, gel elastomers and functional soft adhesives, the viscosity of the inner liquid and semisolid functional core layer at the liquid injection temperature is 500-50000cps, and the volume ratio of the core layer to the outer layer is 1:1.5-1:3.
  2. 2. The thermoplastic polymer 3D printing wire with liquid and semisolid functional core layer according to claim 1, characterized in that the surface roughness Ra of the outer thermoplastic polymer thin-wall tube is less than or equal to 0.8 μm, the roundness error is less than or equal to 0.03mm, the axial tensile strength is more than or equal to 15MPa, and the radial compressive strength is more than or equal to 5MPa.
  3. 3. The thermoplastic polymer 3D printing wire with liquid and semi-solid functional core layer according to claim 1, wherein the inner liquid and semi-solid functional core layer is one or a mixture of two-component epoxy resin, polyurethane prepolymer, silicone liquid rubber, TPR resin slurry, hydrogel, super absorbent resin slurry, PVA-borax gel, magnetorheological fluid, shear thickening fluid; When the viscosity of the inner liquid and semi-solid functional core layer is too low, 2-5% of fumed silica or thixotropic agent is added to improve thixotropic property.
  4. 4. The thermoplastic polymer 3D printing wire with liquid and semi-solid functional core layer according to claim 1, characterized in that the sealing properties of the wire are: Maintaining at 25deg.C and 1MPa for 30min without leakage; At 180-260 ℃, the core layer is not solidified in advance and does not leak when the outer layer is melted.
  5. 5. A coaxial co-extrusion preparation process for preparing the wire rod according to any one of claims 1 to 4, which is characterized by comprising the steps of raw material pretreatment, outer layer melting plasticization, core layer precise conveying, coaxial co-extrusion molding, multistage cooperative cooling shaping, traction rolling and post-treatment; The coaxial co-extrusion preparation process adopts a coaxial co-extrusion die head containing a cold core and hot skin heat insulation design, a double-path pressure balance feeding system and a multistage cooling shaping unit, so as to realize continuous and complete coating of the inner liquid and semi-solid functional core layer by the outer thermoplastic polymer thin-wall tube.
  6. 6. The coaxial coextrusion preparation process according to claim 5, wherein in the raw material pretreatment step, the water content of the outer layer raw material after drying is less than or equal to 0.05%, the core layer raw material is subjected to vacuum defoaming treatment, the vacuum degree is less than or equal to-0.09 MPa, and the defoaming time is 30-60min.
  7. 7. The coaxial coextrusion preparation process according to claim 5, wherein the outer layer melting plasticizing step adopts a single screw extruder with an aspect ratio of 24-40 and a compression ratio of 2.5-3.5, the temperature is controlled in three steps, the extrusion pressure of the outer layer melt is 5-30MPa, the fluctuation range is +/-0.1 MPa, and in the core layer precise conveying step, the injection pressure of the core layer is 0.1-0.5MPa higher than the pressure of the outer layer melt, the feeding speed is 0.1-5ml/min, and the flow accuracy is +/-0.01 ml/min.
  8. 8. The coaxial coextrusion preparation process according to claim 5, wherein the coaxial coextrusion die head comprises an outer annular runner, a central liquid injection needle tube, a self-centering guide cone and a heat insulation structure; The heat insulation structure is a combination of a Teflon coating and an air heat insulation layer or a combination of a Teflon coating and a circulating cooling medium layer; the inner diameter of the central liquid injection needle tube is 0.5-1.0mm, the needle tip extends to the outlet of the die head, and the distance from the end face of the outlet is less than or equal to 5mm; the taper angle of the self-centering guide cone is 6-15 degrees.
  9. 9. The coaxial coextrusion preparation process according to claim 5, wherein in the multistage cooperative cooling shaping step, the air speed of the primary annular air cooling is 1-5m/s, the temperature is 20-30 ℃, the water temperature of the secondary vertical water-falling cooling is 15-35 ℃, the cooling time is 3-5s, and the air speed of the tertiary air cooling water removal is 3-8m/s; And the multistage cooperative cooling shaping step is adopted, so that the outer layer thermoplastic polymer thin-wall tube is completely solidified, and the roundness error of the solidified outer layer thermoplastic polymer thin-wall tube is less than or equal to 0.03mm.
  10. 10. The coaxial coextrusion preparation process according to claim 5, wherein in the drawing and winding step, the drawing speed is 0.5-5m/min, the ratio of the drawing speed to the extrusion speed of the outer layer is 1.0-1.5, the winding tension is 0.5-2.0N, and the wire arrangement distance is 1.2 times of the wire diameter; the post-treatment step comprises the steps of sealing the hot melt adhesive at the two ends of the wire rod, cutting the wire rod according to 100-500 m/coil, filling nitrogen into the sealed package, and storing the wire rod at 20-25 ℃ with humidity less than or equal to 60%.

Description

Thermoplastic polymer 3D printing wire rod containing liquid and semi-solid functional core layer and coaxial co-extrusion preparation process thereof Technical Field The invention relates to the technical field of additive manufacturing, in particular to a thermoplastic polymer 3D printing wire rod containing a liquid and semi-solid functional core layer and a coaxial co-extrusion preparation process thereof. Background The fused deposition modeling technology is called FDM for short, which is one of the most widely applied additive manufacturing technologies, namely 3D printing technologies at present because of the advantages of low equipment cost, simple operation, flexible molding and the like, and the core of the technology depends on thermoplastic polymer consumable materials to realize structural molding, and the existing FDM consumable materials mainly comprise thermoplastic solid materials with single components, such as PLA, ABS, TPU, PETG and the like, and are widely applied to the scenes of industrial model manufacturing, daily article processing, simple structural member molding and the like. In order to meet the complex functional requirements of flexible touch feeling, self-repairing, conductivity, chemical reactivity and the like, various technical attempts have been made in the industry, including the adoption of special direct-writing printing equipment, namely DIW (direct-writing) direct printing of liquid or soft materials such as silica gel, epoxy resin and the like, the development of soft solid consumables such as TPU (thermoplastic polyurethane) and the like, the preparation of composite wires by using a traditional coaxial coating process, and the realization of technical paths such as multi-material composite and the like by multi-material independent extrusion or a double-screw one-step method. However, the prior art has the defects that the special direct-writing printing equipment is high in cost which is 5 to 10 times that of a common FDM printer, a complex suspension structure cannot be printed, the printing equipment depends on a supporting material and has extremely poor universality, the lowest hardness of the existing soft solid consumable materials such as TPU (thermoplastic polyurethane) can only reach 85A, the ultra-soft touch similar to the skin 0A to 20A of a human body cannot be realized, the special self-repairing and responsiveness functions of liquid or gel materials are not realized, the traditional coaxial coating technology is only suitable for a solid core solid shell structure, the composite requirements of external plastic and internal liquid or gel cannot be adapted, the problems of liquid leakage, bamboo joint effect, pipe blockage, poor coaxiality, uneven wall thickness, flat collapse after cooling and the like are easily caused, the multi-material independent extrusion equipment is complex in structure and high in control difficulty, the coating property of the double-screw one-step method on high-viscosity liquid or gel is poor, bubbles and interface stripping are easily generated, and continuous stable production cannot be realized. In addition, the prior art also faces the core technical bottlenecks that the efficient heat insulation design is lacked, the high temperature of the outer layer melt easily causes the early solidification, gasification or denaturation of the core layer fluid, the pressure matching is unbalanced, the outer layer is easily broken due to the fact that the injection pressure of the core layer is too large, gaps are formed due to the fact that the injection pressure of the core layer is too small, the wall thickness is difficult to control, the functional characteristics are lost due to the fact that the wall is too thick, and the extrusion gear is easy to press and break liquid when the wall is too thin. Therefore, development of a special thermoplastic polymer 3D printing wire containing liquid and semisolid functional core layers and a corresponding preparation process thereof are needed, the technical defects of insufficient function expansion, poor equipment suitability, unstable production process, multiple product quality defects and the like in the prior art are overcome, integrated printing of rigid support and flexibility or functional filling is realized, and complex application requirements in multiple fields are met. Disclosure of Invention The invention aims to provide a thermoplastic polymer 3D printing wire rod containing a liquid and semi-solid functional core layer and a coaxial co-extrusion preparation process thereof, so as to solve the problems in the prior art in the background art. In order to achieve the above purpose, the invention provides a technical scheme that a thermoplastic polymer 3D printing wire rod containing liquid and semisolid functional core layers and a coaxial coextrusion preparation process thereof are of a coaxial core-shell structure, and comprise an outer thermoplastic polymer thin-