3D printing wire rod and preparation method thereof

Abstract

The invention discloses a 3D printing wire rod and a preparation method thereof, and belongs to the technical field of 3D printing wire rods. The 3D printing wire rod comprises a center layer, a bonding layer and a surface layer which are arranged from inside to outside; and the central layer, the surface layer and the bonding layer are prepared from different polymer-based materials. The bonding layer is arranged between the central layer and the surface layer, so that the bonding of the central layer material and the surface layer material can be effectively improved, and the problem that printability and functionality of a uniform blending material are difficult to consider at the same time is solved. The preparation method comprises the following steps that preparation raw materials of the center layer, preparation raw materials of the bonding layer and preparation raw materials of the surface layer are matched to be subjected to extrusion forming, cooling and traction, the 3D printing wire is formed, and the method is simple, easy to operate and capable of achieving industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing wires, and in particular to a 3D printing wire and a preparation method thereof. Background Art

[0002] In extrusion 3D printing, fused filament fabrication (FFF) melts the polymer wire by heating, and deposits the melt layer by layer on the base after it is extruded from the nozzle to achieve 3D printing of the object. Due to the unique process characteristics of FFF 3D printing (such as a large number of non-steady states + complex thermal history), this technology places high demands on the "printability" of the material. "Printability" generally refers to the ability of a polymer material to be formed under FFF process conditions (which can be evaluated by extrusion, deposition, fusion, draping, wire drawing, warping, bridging, nozzle wear, etc.), or the width of the processing window under the conditions of forming. In addition to printability, the rapidly expanding application areas of FFF technology also place higher demands on the functionality of the material; and the functional design needs to be completed on the basis of ensuring printability, which leads to greater complexity and challenges in the design of functional 3D printing materials compared with traditional polymer materials. For this reason, the lack of materials that are both printable and functional is still an important bottleneck problem that currently restricts the wider application of FFF technology.

[0003] Melt blending modification is the mainstream modification technology for extrusion-type 3D printing polymer materials. Its technical principle is to melt and mix multiple materials at a certain temperature, and prepare a blended composite material with a multiphase structure under the joint action of a certain external force field and temperature field. Its core technical idea is to make composite materials by taking advantage of the strengths of multiple materials with different properties. However, in the actual preparation process, the existence of many problems makes it difficult for 3D printing filaments based on melt blending modification technology to achieve both printability and functionality.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The object of the present invention is to provide a 3D printing wire and a preparation method thereof, so as to solve or improve the above-mentioned technical problems.

[0006] This application can be implemented as follows:

[0007] In a first aspect, the present application provides a 3D printing wire, which includes a center layer, an adhesive layer, and a skin layer arranged from inside to outside;

[0008] The raw materials for preparing the skin layer, the core layer and the adhesive layer are different polymer-based materials.

[0009] In an optional embodiment, the 3D printing wire includes at least one of the following features:

[0010] Feature 1: The chemical composition of 3D printing filaments is distributed in layers along the circumference of the filaments;

[0011] Feature 2: The volume fraction of the central layer is 1-98.9%, preferably 20-79%;

[0012] Feature 3: The volume fraction of the adhesive layer is 0.01-20%, preferably 1-10%;

[0013] Feature 4: The volume fraction of the epidermis is 1-98.9%, preferably 20-79%;

[0014] Feature 5: The thickness of the adhesive layer is 1-500μm;

[0015] Feature 6: The raw material for preparing the adhesive layer is a material that can be at least partially fused with the raw material for preparing the core layer and the raw material for preparing the skin layer.

[0016] In an optional embodiment, the raw material for preparing the central layer includes at least one of polyolefin and a copolymer of polyolefin.

[0017] In an optional embodiment, the raw material for preparing the central layer includes at least one of thermoplastic polyolefin and polyolefin elastomer.

[0018] In an alternative embodiment, the thermoplastic polyolefin includes at least one of polyethylene, polypropylene, polymethylpentene, and polybutene-1.

[0019] In an alternative embodiment, the polyolefin elastomer includes at least one of polyisobutylene, ethylene propylene rubber and ethylene propylene diene monomer rubber.

[0020] In an optional embodiment, the raw material for preparing the central layer includes at least one of polyamide and a copolymer of polyamide.

[0021] In an optional embodiment, the polyamide includes at least one of nylon 6, nylon 6 elastomer, nylon 66, binary copolymer nylon 66 / 6, nylon 11, nylon 11 elastomer, nylon 12, nylon 12 elastomer, nylon 1010, nylon 1012 and nylon 610.

[0022] In an optional embodiment, the raw material for preparing the central layer includes at least one of polyester and a copolymer of polyester.

[0023] In an alternative embodiment, the polyester includes at least one of polyethylene terephthalate, polybutylene terephthalate, and polyarylate.

[0024] In an optional embodiment, the raw material for preparing the central layer includes at least one of polycarbonate and a copolymer of polycarbonate.

[0025] In an optional embodiment, the raw material for preparing the central layer includes polyoxymethylene and a copolymer of polyoxymethylene.

[0026] In an optional embodiment, the raw material for preparing the central layer includes at least one of polyphenylene ether and a copolymer of polyphenylene ether.

[0027] In an optional embodiment, the raw material for preparing the central layer includes at least one of polyphenylene sulfide and a copolymer of polyphenylene sulfide.

[0028] In an optional embodiment, the raw material for preparing the central layer includes at least one of polyetheretherketone and a copolymer of polyetheretherketone.

[0029] In an optional embodiment, the raw material for preparing the central layer includes at least one of polysulfone and a copolymer of polysulfone.

[0030] In an optional embodiment, the raw material for preparing the central layer includes at least one of a liquid crystal polymer material and a copolymer of a liquid crystal polymer material.

[0031] In an optional embodiment, the raw material for preparing the skin layer includes at least one of polyolefin and a copolymer of polyolefin.

[0032] In an optional embodiment, the raw material for preparing the skin layer includes at least one of thermoplastic polyolefin and polyolefin elastomer.

[0033] In an alternative embodiment, the thermoplastic polyolefin includes at least one of polyethylene, polypropylene, polymethylpentene, and polybutene-1.

[0034] In an alternative embodiment, the polyolefin elastomer includes at least one of polyisobutylene, ethylene propylene rubber and ethylene propylene diene monomer rubber.

[0035] In an optional embodiment, the raw material for preparing the skin layer includes at least one of polyamide and a copolymer of polyamide.

[0036] In an optional embodiment, the polyamide includes at least one of nylon 6, nylon 6 elastomer, nylon 66, binary copolymer nylon 66 / 6, nylon 11, nylon 11 elastomer, nylon 12, nylon 12 elastomer, nylon 1010, nylon 1012 and nylon 610.

[0037] In an optional embodiment, the raw material for preparing the skin layer includes at least one of polyester and a copolymer of polyester.

[0038] In an alternative embodiment, the polyester includes at least one of polyethylene terephthalate, polybutylene terephthalate, and polyarylate.

[0039] In an optional embodiment, the raw material for preparing the skin layer includes at least one of polycarbonate and a copolymer of polycarbonate.

[0040] In an optional embodiment, the raw materials for preparing the skin layer include polyoxymethylene and a copolymer of polyoxymethylene.

[0041] In an optional embodiment, the raw material for preparing the skin layer includes at least one of polyphenylene ether and a copolymer of polyphenylene ether.

[0042] In an optional embodiment, the raw material for preparing the skin layer includes at least one of polyphenylene sulfide and a copolymer of polyphenylene sulfide.

[0043] In an optional embodiment, the raw material for preparing the skin layer includes at least one of polyetheretherketone and a copolymer of polyetheretherketone.

[0044] In an optional embodiment, the raw material for preparing the skin layer includes at least one of polysulfone and a copolymer of polysulfone.

[0045] In an optional embodiment, the raw material for preparing the skin layer includes at least one of a liquid crystal polymer material and a copolymer of a liquid crystal polymer material.

[0046] In an optional embodiment, the preparation material of the adhesive layer includes at least one of a polyolefin polymer grafted with polar molecules, a polyolefin polymer grafted with polar groups, and a copolymer-modified polyolefin polymer.

[0047] In an optional embodiment, the polar molecules include at least one of anhydrides, epoxies, acids, vinyl acetates, acrylates, methacrylates, and polyolefins.

[0048] In an alternative embodiment, the anhydride comprises maleic anhydride;

[0049] and / or, the epoxies include glycidyl methacrylate;

[0050] and / or, the acid comprises at least one of acrylic acid and methacrylic acid;

[0051] and / or, the acrylates include at least one of ethyl acrylate and butyl acrylate;

[0052] and / or, the methacrylates include at least one of methacrylate and methyl methacrylate;

[0053] And / or, the polyolefins include at least one of polyethylene, polypropylene, polystyrene, acrylonitrile-butadiene-styrene copolymer and polyolefin elastomer.

[0054] In an optional embodiment, the raw material for preparing the central layer and the raw material for preparing the skin layer are both polymer-based materials, and the raw material for preparing the central layer and the raw material for preparing the skin layer have different crystallization behaviors.

[0055] In an alternative embodiment, the crystallization behavior includes at least one of a crystallization rate, a crystal morphology, and a crystallinity.

[0056] In an optional embodiment, the crystallization rate of the raw material for preparing the center layer is lower than the crystallization rate of the raw material for preparing the skin layer.

[0057] In an alternative embodiment, the crystallinity of the raw material for preparing the center layer is lower than the crystallinity of the raw material for preparing the skin layer.

[0058] In an alternative embodiment, the skin layer is prepared from a semi-crystalline polymer.

[0059] In an optional embodiment, the raw material for preparing the central layer is polycarbonate, the raw material for preparing the skin layer is high-density polyethylene, and the raw material for preparing the adhesive layer is maleic anhydride grafted polyethylene.

[0060] In an optional embodiment, the raw material for preparing the central layer and the raw material for preparing the skin layer are both polymer-based materials, and the glass transition temperature of the raw material for preparing the central layer and the glass transition temperature of the raw material for preparing the skin layer are different.

[0061] In an optional embodiment, the glass transition temperature of the raw material for preparing the core layer and the glass transition temperature of the raw material for preparing the skin layer are independently -80°C to -380°C.

[0062] In an optional embodiment, the difference between the glass transition temperature of the raw material for preparing the core layer and the glass transition temperature of the raw material for preparing the skin layer is 1°C to 300°C.

[0063] In an optional embodiment, the raw material for preparing the central layer is polycarbonate, the raw material for preparing the skin layer is acrylonitrile-butadiene-styrene copolymer, and the raw material for preparing the adhesive layer is maleic anhydride grafted acrylonitrile-butadiene-styrene copolymer.

[0064] In an optional embodiment, the raw material for preparing the central layer and the raw material for preparing the skin layer are both polymer-based materials, and the elastic tensile modulus of the raw material for preparing the central layer and the tensile elastic modulus of the raw material for preparing the skin layer are different.

[0065] In an optional embodiment, the elastic tensile modulus of the raw material for preparing the core layer and the elastic tensile modulus of the raw material for preparing the skin layer are independently 1 MPa-10 GPa.

[0066] In an optional embodiment, the difference between the elastic tensile modulus of the raw material for preparing the core layer and the elastic tensile modulus of the raw material for preparing the skin layer is 1 MPa-5 GPa.

[0067] In an optional embodiment, the raw material for preparing the central layer is polylactic acid, the raw material for preparing the skin layer is thermoplastic polyurethane, and the raw material for preparing the adhesive layer is ethylene-acrylate-glycidyl ester.

[0068] In a second aspect, the present application provides a method for preparing a 3D printing wire as in any of the aforementioned embodiments, comprising the following steps: extruding, cooling, and pulling the raw materials for preparing the center layer, the raw materials for preparing the bonding layer, and the raw materials for preparing the skin layer to form a 3D printing wire.

[0069] In an optional embodiment, the raw materials for preparing the center layer, the raw materials for preparing the bonding layer, and the raw materials for preparing the skin layer are melted in different single-screw extruders respectively to obtain a center layer melt, a bonding layer melt, and a skin layer melt; the center layer melt, the bonding layer melt, and the skin layer melt are extruded through the same die.

[0070] The beneficial effects of this application include:

[0071] The 3D printing wire provided by the present application includes a center layer, an adhesive layer and a skin layer arranged from the inside to the outside; the raw materials for preparing the center layer, the adhesive layer and the skin layer are different polymer-based materials. The above scheme creatively arranges an adhesive layer between the center layer and the skin layer, which can effectively improve the bonding between the center layer material and the skin layer material, and solve the problem that it is difficult to balance the printability and functionality of the uniformly blended material. Its preparation method includes the following steps: extruding, cooling and pulling the raw materials for preparing the center layer, the raw materials for preparing the adhesive layer and the raw materials for preparing the skin layer to form a 3D printing wire. The preparation method is simple, easy to operate and can be industrialized. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0073] Figure 1 This is a schematic diagram of the structure of the 3D printing wire in the embodiment of the present application;

[0074] Figure 2 This is a schematic diagram of a 3D printing wire preparation device in an embodiment of the present application.

[0075] Icons: 1-first single-screw extruder; 2-second single-screw extruder; 3-third single-screw extruder; 4-melt co-extrusion die; 11-skin layer; 12-adhesive layer; 13-center layer; 14-3D printing filament. DETAILED DESCRIPTION

[0076] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0077] The 3D printing wire and its preparation method provided in this application are described in detail below.

[0078] The inventors creatively discovered that the reasons why the current 3D printing filaments using melt blending modification technology are difficult to achieve both printability and functionality may include: using the existing melt blending modification technology in the filament during extrusion 3D printing, the dispersed multiphase structure will lead to weakened bonding between printed layers.

[0079] Based on this, the present application creatively proposes a 3D printing wire, which includes a center layer, an adhesive layer and a skin layer arranged from the inside to the outside.

[0080] The raw materials for preparing the core layer, the skin layer and the adhesive layer are different polymer-based materials. The raw material for preparing the adhesive layer is a material that can at least partially fuse with the raw material for preparing the core layer and the raw material for preparing the skin layer.

[0081] In the wire, the introduction of the adhesive layer can improve the adhesion between the core layer and the skin layer, which is beneficial to improving the printability and functionality of the uniform blended material.

[0082] In some embodiments, the chemical composition of the 3D printing wire can be distributed in layers along the circumference of the wire. In terms of the layered distribution of the chemical composition, during the melt extrusion process, the laminar flow can maintain the three-layer distribution structure well, which is conducive to solving the problem of the difficulty in balancing printability and functionality compared to a simple blended material with a center layer and a skin layer.

[0083] For reference, based on the above-mentioned layered distribution, if the adhesive layer is made of resin material, the incompatibility problem between the center layer and the surface layer material interface can be solved, and interface defects in the wire and the printed part can be avoided.

[0084] In the 3D printing wire of the present application, the volume fraction of the central layer can be 1-98.9%, such as 1%, 2%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95% or 98.9%, etc., or any other value within the range of 1-98.9%. In some typical embodiments, the volume fraction of the central layer is 20-79%.

[0085] The volume fraction of the adhesive layer can be 0.01-20%, such as 0.01%, 0.02%, 0.05%, 0.1%, 0.2%, 0.5%, 1%, 2%, 5%, 10%, 15% or 20%, etc., or any other value within the range of 0.01-20%. In some typical embodiments, the volume fraction of the adhesive layer is 1-10%.

[0086] The volume fraction of the epidermis layer can be 1-98.9%, such as 1%, 2%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95% or 98.9%, etc., or any other value within the range of 1-98.9%. In some typical embodiments, the volume fraction of the epidermis layer is 20-79%.

[0087] The sum of the volume fraction of the core layer, the volume fraction of the adhesive layer and the volume fraction of the skin layer is 100%.

[0088] In some embodiments, the thickness of the adhesive layer can be 1-500 μm, such as 1 μm, 2 μm, 5 μm, 10 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm or 500 μm, etc., or it can be any other value within the range of 1-500 μm.

[0089] By controlling the thickness of the adhesive layer within the above range, it is more advantageous to improve the adhesion between the core layer and the skin layer and the uniformity during the blending process.

[0090] In some embodiments of the present application, the raw material for preparing the center layer may include at least one of polyolefins and copolymers of polyolefins. Polyolefins are high molecular weight compounds formed by addition polymerization of olefins. Such organic polymers are usually formed by polymerization of many identical or different simple olefin molecules (such as alpha-olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, and some cycloolefins). In some embodiments, the raw material for preparing the above-mentioned center layer may include, for example, at least one of thermoplastic polyolefins and polyolefin elastomers. Among them, thermoplastic polyolefins may exemplarily but not limitatively include at least one of polyethylene (PE), polypropylene (PP), polymethylpentene (PMP) and polybutene-1 (PB-1). Polyolefin elastomers (POE) may exemplarily but not limitatively include at least one of polyisobutylene (PIB), ethylene-propylene rubber (EPR) and ethylene-propylene-diene rubber (EPDM). In the present application, polyolefin materials refer to materials based on polymers obtained by polymerization or copolymerization of one or more olefins.

[0091] It should be noted that the above-mentioned thermoplastic polyolefin refers to a polymer having properties similar to plastics, while the polyolefin elastomer refers to a polymer having properties similar to rubbers.

[0092] In other embodiments of the present application, the raw material for preparing the center layer may include at least one of polyamide and a copolymer of polyamide. The above-mentioned polyamide (PA) is a polymer polymerized by amide bonds from monomers containing carboxyl groups and amino groups. For reference, the above-mentioned polyamide may also be referred to as nylon, and nylon generally refers to a condensation polymer whose constituent units can be connected by amides. Exemplarily, the above-mentioned polyamide may include at least one of nylon 6, nylon 6 elastomer, nylon 66, binary copolymer nylon 66 / 6, nylon 11, nylon 11 elastomer, nylon 12, nylon 12 elastomer, nylon 1010, nylon 1012 and nylon 610. It should be noted that the above-mentioned nylon 6 elastomer is a block copolymer, nylon 6 is used as a hard segment, and polyether or polyester is used as a soft segment. Similarly, in the nylon 11 elastomer, nylon 11 is used as a hard segment, and polyether or polyester is used as a soft segment. In nylon 12 elastomer, nylon 12 is used as the hard segment and polyether or polyester is used as the soft segment.

[0093] In other embodiments of the present application, the raw material for preparing the center layer may include at least one of polyester and polyester copolymer. Polyester is a general term for polymers obtained by polycondensation of polyols and polyacids. In the present application, polyester may exemplarily but not limitatively include at least one of linear thermoplastic resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT) and polyarylate.

[0094] In other embodiments of the present application, the raw material for preparing the central layer may include at least one of polycarbonate and a copolymer of polycarbonate. Polycarbonate (PC), also known as PC plastic, is a high molecular polymer containing carbonate groups in the molecular chain, which can be divided into aliphatic, aromatic, aliphatic-aromatic and other types according to the structure of the ester group.

[0095] In other embodiments of the present application, the raw material for preparing the center layer may include at least one of polyoxymethylene and a copolymer of polyoxymethylene. Among them, polyoxymethylene (POM), also known as acetal resin, polyoxymethylene or polyacetal, is a thermoplastic crystalline polymer.

[0096] In other embodiments of the present application, the raw material for preparing the central layer may include at least one of polyphenylene ether and a copolymer of polyphenylene ether. Polyphenylene ether (PPE) is a high-temperature thermoplastic plastic, also known as polyoxylene (PPO), which is a non-crystalline thermoplastic polymer.

[0097] In other embodiments of the present application, the raw material for preparing the central layer may include at least one of polyphenylene sulfide and a copolymer of polyphenylene sulfide. Polyphenylene sulfide (PPS) is a polymer containing a repeating structural unit of p-phenylene sulfide in the molecule.

[0098] In other embodiments of the present application, the raw material for preparing the central layer includes at least one of polyetheretherketone and a copolymer of polyetheretherketone. Polyetheretherketone (PEEK) is a linear aromatic polymer compound, the constituent units of which are oxygen-p-phenylene-carbonyl-p-phenylene, and is a semi-crystalline thermoplastic.

[0099] In other embodiments of the present application, the raw material for preparing the central layer may include at least one of polysulfone and a copolymer of polysulfone.

[0100] In some other embodiments of the present application, the raw material for preparing the central layer may include at least one of a liquid crystal polymer material and a copolymer of a liquid crystal polymer material. Liquid crystal polymer, also known as liquid crystal polymer (LCP), is a new type of polymer material that generally turns into a liquid crystal under certain heating conditions.

[0101] In the present application, the raw materials for preparing the epidermis may also include at least one of polyolefins and copolymers of polyolefins, or include at least one of thermoplastic polyolefins and polyolefin elastomers, or include at least one of polyamides and copolymers of polyamides, or include at least one of polyesters and copolymers of polyesters, or include at least one of polycarbonates and copolymers of polycarbonates, or include at least one of polyoxymethylene and copolymers of polyoxymethylene; or include at least one of polyphenylene ether and copolymers of polyphenylene ether, or include at least one of polyphenylene sulfide and copolymers of polyphenylene sulfide, or include at least one of copolymers of polyetheretherketone and polyetheretherketone, or include at least one of copolymers of polysulfone and polysulfone, or include at least one of liquid crystal polymer materials and copolymers of liquid crystal polymer materials.

[0102] The thermoplastic polyolefin may also include at least one of polyethylene, polypropylene, polymethylpentene and polybutene-1. The polyolefin elastomer may also include at least one of polyisobutylene, ethylene propylene rubber and ethylene propylene diene monomer rubber. The polyamide may also include at least one of nylon 6, nylon 6 elastomer, nylon 66, binary copolymer nylon 66 / 6, nylon 11, nylon 11 elastomer, nylon 12, nylon 12 elastomer, nylon 1010, nylon 1012 and nylon 610.

[0103] In the present application, the preparation material of the adhesive layer may include at least one of a polyolefin polymer grafted with a polar molecule, a polyolefin polymer grafted with a polar group, and a copolymer-modified polyolefin polymer.

[0104] For reference, polar molecules may exemplarily but not limitatively include at least one of anhydrides, epoxies, acids, vinyl acetate, acrylates, methacrylates, and polyolefins. Among them, anhydrides may exemplarily but not limitatively include maleic anhydride (MA). Epoxies may exemplarily but not limitatively include glycidyl methacrylate (GMA). Acids may exemplarily but not limitatively include at least one of acrylic acid (AA) and methacrylic acid (MAA). Acrylates may exemplarily but not limitatively include at least one of ethyl acrylate and butyl acrylate. Methacrylates may exemplarily but not limitatively include at least one of methacrylate and methyl methacrylate. Polyolefins may exemplarily but not limitatively include at least one of polyethylene (PE), polypropylene (PP), polystyrene (PS), acrylonitrile-butadiene-styrene copolymer (ABS), and polyolefin elastomer (POE).

[0105] The adhesive layer is mainly used to achieve the bonding of the materials used for the central layer and the skin layer. The raw materials used to prepare the adhesive layer are compatible with the raw materials used to prepare the central layer and the raw materials used to prepare the skin layer.

[0106] In some typical embodiments, the raw materials for the core layer and the raw materials for the skin layer are both polymer-based materials, and the raw materials for the core layer and the raw materials for the skin layer have different crystallization behaviors. The crystallization behavior may exemplarily but not limitatively include at least one of crystallization rate, crystal morphology, and crystallinity.

[0107] For example, the crystallization rate of the raw material of the core layer is lower than the crystallization rate of the raw material of the skin layer. Alternatively, the crystallinity of the raw material of the core layer is lower than the crystallinity of the raw material of the skin layer. In some preferred embodiments, the raw material of the skin layer is a semi-crystalline polymer.

[0108] It should be noted that crystallization is the process of polymer molecular chains arranging to form ordered regions. If the crystalline region of the polymer is too dense, the polymer print will be prone to uneven deformation during the printing process, resulting in warping, and dimensional accuracy is difficult to guarantee. By using an amorphous polymer or a polymer with a slow crystallization rate as the center layer, and a semi-crystalline polymer with a faster crystallization rate or higher crystallinity as the skin layer, during the printing process, the polymer in the center layer is first shaped, and when the polymer in the skin layer crystallizes, thanks to the effect of the adhesion layer, the polymer material in the center layer can suppress the deformation caused by the crystallization of the polymer in the skin layer. The semi-crystalline 3D printing material obtained in this way has better warping resistance during printing.

[0109] As an example, the raw material for preparing the core layer may be polycarbonate, the raw material for preparing the skin layer may be high-density polyethylene, and the raw material for preparing the adhesive layer may be maleic anhydride grafted polyethylene.

[0110] In some other typical embodiments, the raw materials for preparing the central layer and the raw materials for preparing the epidermis layer are both polymer-based materials, and the glass transition temperature of the raw materials for preparing the central layer and the glass transition temperature of the raw materials for preparing the epidermis layer are different. For example, the raw materials for preparing the central layer may be high Tg materials, and the raw materials for preparing the epidermis layer may be low Tg materials; or, the raw materials for preparing the central layer may be low Tg materials, and the raw materials for preparing the epidermis layer may be high Tg materials.

[0111] Glass transition temperature (Tg) refers to the temperature at which a glassy material reversibly transforms between a glassy state and a highly elastic state. The glass transition temperature (Tg) of a polymer material is one of the characteristic temperatures of a high molecular weight polymer, corresponding to the temperature at which the molecular segments begin to move during the heating process of the polymer material. There are a variety of measurement methods, namely, by measuring the physical property changes during the glass transition of the polymer material, the glass transition temperature can be measured. Exemplarily, the measurement method generally includes 4 types: volume change (expansion meter method), thermodynamic properties (differential thermal analysis DTA and differential scanning calorimetry DSC) and mechanical property changes (thermomechanical method, stress relaxation method and dynamic mechanical relaxation method DMA) and electromagnetic effect (dielectric relaxation method). The Tg values ​​measured by different test methods are different and do not have the general comparability. The description of the Tg value referred to in this application is the comparison of Tg values ​​under the same test method and test conditions.

[0112] For example, the glass transition temperature of the raw material for the core layer and the glass transition temperature of the raw material for the skin layer are independently -80°C to -380°C (such as -80°C, -100°C, -150°C, -200°C, -250°C, -300°C, -350°C or -380°C, etc.). Preferably, the difference between the glass transition temperature of the raw material for the core layer and the glass transition temperature of the raw material for the skin layer is 1°C to 300°C (such as 1°C, 2°C, 5°C, 10°C, 50°C, 100°C, 150°C, 200°C, 250°C or 300°C, etc.).

[0113] By using materials with different glass transition temperatures as the raw materials for preparing the core layer and the skin layer respectively, the resulting 3D printing material can have the following characteristics: while obtaining high heat resistance, the material maintains good printability, such as excellent interlayer performance and the ability to resist warping. In addition, excellent comprehensive mechanical properties can also be obtained, including better tensile strength, flexural strength and notched impact strength.

[0114] As an example, the raw material for preparing the core layer may be polycarbonate, the raw material for preparing the skin layer may be acrylonitrile-butadiene-styrene copolymer, and the raw material for preparing the adhesive layer may be maleic anhydride grafted acrylonitrile-butadiene-styrene copolymer.

[0115] In some other typical embodiments, the raw materials for the preparation of the center layer and the raw materials for the preparation of the skin layer are both polymer-based materials, and the elastic tensile modulus of the raw materials for the preparation of the center layer is different from the tensile elastic modulus of the raw materials for the preparation of the skin layer. For example, the elastic tensile modulus of the raw materials for the preparation of the center layer may be greater than the elastic tensile modulus of the raw materials for the preparation of the skin layer (which is beneficial to improving the interlayer toughness and obtaining a rigid-toughness balanced material with high overall stiffness and excellent interlayer toughness); or, the elastic tensile modulus of the raw materials for the preparation of the center layer may be less than the elastic tensile modulus of the raw materials for the preparation of the skin layer.

[0116] The tensile modulus of polymer materials is an important method and performance parameter for characterizing the rigidity of polymer materials. It is measured by a tensile test of a standard spline. The spline size and test conditions will affect the test results to a certain extent. In this application, the relative size comparison of the tensile modulus values ​​of polymer materials adopts the same test method standard, spline size and test conditions (tensile rate). The test method can refer to the standards GB / T 1040-2018 and ISO 527:2012, and a tensile test speed of 1 mm / min is used.

[0117] The tensile modulus of a solid material can characterize the mechanical properties of the stiffness of the solid material. It is defined as the ratio of its tensile stress (per unit area) to its strain (relative deformation) when undergoing elastic deformation; in some cases, the tensile modulus can be used to evaluate the stiffness of a material, in other words, the material is expected to deform (elastic) when subjected to a specific load. The higher the tensile modulus of a material, the more force is required to deform. The tensile modulus of elasticity in this application can also be referred to as the tensile modulus, which refers to the elasticity of a material when stretched. In some cases, the value of the tensile modulus is the ratio of the force required to stretch a material per unit length along the central axis to its cross-sectional area. In application, the calculation formula of the tensile modulus is: tensile modulus (N / (m×m)) = f / S (N / (m×m)); wherein f represents the required force, S represents the cross-sectional area of ​​the material, and N represents the required force.

[0118] For example, the elastic tensile modulus of the raw material for preparing the core layer and the elastic tensile modulus of the raw material for preparing the skin layer are independently 1MPa-10GPa (such as 1MPa, 5MPa, 10MPa, 50MPa, 100MPa, 500MPa, 1GPa, 2GPa, 5GPa, 8GPa or 10GPa, etc.). Preferably, the difference between the elastic tensile modulus of the raw material for preparing the core layer and the elastic tensile modulus of the raw material for preparing the skin layer is 1MPa-5GPa.

[0119] As an example, the raw material for preparing the core layer may be polylactic acid, the raw material for preparing the skin layer may be thermoplastic polyurethane, and the raw material for preparing the adhesive layer may be ethylene-acrylate-glycidyl ester.

[0120] By using materials with different elastic tensile moduli as the raw materials for the preparation of the core layer and the skin layer, the overall rigidity of the soft wire can be improved, the extrusion and conveying properties of the soft elastomer material during printing can be improved, and problems such as wire slippage can be solved, thereby making the wire conveying of the print head part in 3D printing smoother and helping to improve printing efficiency.

[0121] In addition, the present application also provides a method for preparing the above-mentioned 3D printing wire, which may include the following steps: combining the raw materials for preparing the center layer, the raw materials for preparing the adhesive layer, and the raw materials for preparing the skin layer for extrusion molding, cooling, and pulling to form the 3D printing wire.

[0122] For reference, the raw materials for the preparation of the center layer, the raw materials for the preparation of the adhesive layer, and the raw materials for the preparation of the skin layer can be placed in different melt extrusion devices (single-screw extruders) respectively, and the melts of the three materials are extruded through the same die by quantitatively controlling the extrusion flow rate, and then cooled and pulled to form a 3D printing wire, and finally a structural wire containing three layers of materials is obtained. It can also be understood as: the raw materials for the preparation of the center layer, the raw materials for the preparation of the adhesive layer, and the raw materials for the preparation of the skin layer are melted in different single-screw extruders to obtain the center layer melt, the adhesive layer melt, and the skin layer melt; the center layer melt, the adhesive layer melt, and the skin layer melt are extruded through the same die.

[0123] In order to achieve good fusion between the bonding layer material and the interface between the center layer material and the skin layer material, the temperature, speed and other processes of the melt extrusion device can be adjusted so that all three materials can be stably melted and stably extruded and fed, and the volume flow rate of the corresponding materials can be kept consistent during continuous production. In addition, the temperature of the die flow channel also corresponds to the intersection of the three materials in the molten state. After the intersection, the flow rate of the three material melts is consistent, and no turbulence or disturbance occurs during the melt flow process, and it is ensured that the three materials can be stably extruded in a viscous melt state at the die setting temperature.

[0124] For reference, taking the example that the raw material for the center layer is polypropylene, the raw material for the skin layer is nylon 6, and the raw material for the bonding layer is maleic anhydride grafted modified polypropylene, accordingly, the raw material for the center layer is melted at 210-230°C, the raw material for the skin layer is melted at 245-270°C, the raw material for the bonding layer is melted at 215-235°C, and the temperature of the die is 235-255°C.

[0125] Typically, the extrusion equipment used in the above preparation process includes a first single screw extruder, a second single screw extruder, a third single screw extruder and a melt co-extrusion die. The melt extrusion temperature of the first single screw extruder is 220°C (corresponding to the preparation raw material of the center layer), the melt extrusion temperature of the second single screw extruder is 260°C (corresponding to the preparation raw material of the bonding layer), the melt extrusion temperature of the third single screw extruder is 230°C (corresponding to the preparation raw material of the skin layer), and the die temperature is 240°C.

[0126] As mentioned above, the preparation method of the 3D printing wire provided in the present application is simple, easy to operate, and has controllable conditions. It can also be applied to industrial production, and the obtained 3D printing wire can effectively take into account both printability and functionality.

[0127] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0128] Example 1

[0129] This embodiment provides a 3D printing wire 14, such as Figure 1 As shown, the chemical composition is distributed in layers along the circumference of the wire, including a center layer 13, an adhesive layer 12 and a skin layer 11 from the inside to the outside.

[0130] The raw material of the core layer 13 is polycarbonate (PC), the raw material of the skin layer 11 is high-density polyethylene (HDPE), and the raw material of the adhesive layer 12 is maleic anhydride grafted polyethylene (MA-PE). The volume fraction of the core layer 13 in the 3D printing wire 14 is 55%, the volume fraction of the adhesive layer 12 in the 3D printing wire 14 is 2%, the volume fraction of the skin layer 11 in the 3D printing wire 14 is 43%, and the thickness of the adhesive layer 12 is 12 μm.

[0131] The preparation process of the 3D printing wire 14 includes: extruding polycarbonate in a first single screw extruder 1 (combined with Figure 2 ) is melt-extruded at a temperature of 260°C, the maleic anhydride grafted polyethylene is melt-extruded at a temperature of 210°C in a second single-screw extruder 2, and the high-density polyethylene is melt-extruded at a temperature of 215°C in a third single-screw extruder 3; the polycarbonate melt, the maleic anhydride grafted polyethylene melt and the high-density polyethylene melt are extruded through the same melt co-extrusion die 4 at 235°C, cooled, and pulled to obtain a 3D printing wire 14 containing three layers of materials.

[0132] Example 2

[0133] This embodiment provides a 3D printing wire 14, such as Figure 1 As shown, the chemical composition is distributed in layers along the circumference of the wire, including a center layer 13, an adhesive layer 12 and a skin layer 11 from the inside to the outside.

[0134] The raw material for preparing the core layer 13 is polycarbonate (PC), the raw material for preparing the skin layer 11 is acrylonitrile-butadiene-styrene copolymer (ABS), and the raw material for preparing the adhesive layer 12 is maleic anhydride grafted ABS (MA-ABS). The volume fraction of the core layer 13 in the 3D printing wire 14 is 70%, the volume fraction of the adhesive layer 12 in the 3D printing wire 14 is 5%, the volume fraction of the skin layer 11 in the 3D printing wire 14 is 25%, and the thickness of the adhesive layer 12 is 26 μm.

[0135] The preparation process of the 3D printing wire 14 includes: extruding polycarbonate in a first single screw extruder 1 (combined with Figure 2 ) is melt-extruded at a temperature of 260°C, the maleic anhydride grafted ABS is melt-extruded at a temperature of 255°C in a second single-screw extruder 2, and the acrylonitrile-butadiene-styrene copolymer is melt-extruded at a temperature of 250°C in a third single-screw extruder 3; the polycarbonate melt, the maleic anhydride grafted ABS melt and the acrylonitrile-butadiene-styrene copolymer melt are extruded through the same melt co-extrusion die 4 at 250°C, cooled, and pulled to obtain a 3D printing wire 14 containing three layers of materials.

[0136] Example 3

[0137] This embodiment provides a 3D printing wire 14, such as Figure 1 As shown, the chemical composition is distributed in layers along the circumference of the wire, including a center layer 13, an adhesive layer 12 and a skin layer 11 from the inside to the outside.

[0138] The raw material of the core layer 13 is polylactic acid (PLA), the raw material of the skin layer 11 is thermoplastic polyurethane (TPU), and the raw material of the adhesive layer 12 is ethylene-glycidyl acrylate (EGMA). The volume fraction of the core layer 13 in the 3D printing wire 14 is 45%, the volume fraction of the adhesive layer 12 in the 3D printing wire 14 is 3%, the volume fraction of the skin layer 11 in the 3D printing wire 14 is 52%, and the thickness of the adhesive layer 12 is 20 μm.

[0139] The preparation process of the 3D printing wire 14 includes: extruding polylactic acid in a first single screw extruder 1 (combined with Figure 2 ) is melt-extruded at a temperature of 210°C, ethylene-acrylate-glycidyl ester is melt-extruded at a temperature of 190°C in a second single-screw extruder 2, and thermoplastic polyurethane is melt-extruded at a temperature of 215°C in a third single-screw extruder 3; the polylactic acid melt, ethylene-acrylate-glycidyl ester melt and thermoplastic polyurethane melt are extruded through the same melt co-extrusion die 4 at 210°C, cooled, and pulled to obtain a 3D printing wire 14 containing three layers of materials.

[0140] Example 4

[0141] This embodiment provides a 3D printing wire 14, such as Figure 1 As shown, the chemical composition is distributed in layers along the circumference of the wire, including a center layer 13, an adhesive layer 12 and a skin layer 11 from the inside to the outside.

[0142] The raw material for preparing the central layer 13 is polypropylene (PP), the raw material for preparing the skin layer 11 is nylon 6 (PA6), and the raw material for preparing the adhesive layer 12 is maleic anhydride grafted modified polypropylene (MA-PP). The volume fraction of the central layer 13 in the 3D printing wire 14 is 70%, the volume fraction of the adhesive layer 12 in the 3D printing wire 14 is 6%, the volume fraction of the skin layer 11 in the 3D printing wire 14 is 24%, and the thickness of the adhesive layer 12 is 30 μm.

[0143] The preparation process of the 3D printing wire 14 includes: extruding polypropylene in a first single screw extruder 1 (combined with Figure 2 ) is melt-extruded at a temperature of 220°C, the maleic anhydride grafted modified polypropylene is melt-extruded at a temperature of 230°C in a second single-screw extruder 2, and nylon 6 is melt-extruded at a temperature of 260°C in a third single-screw extruder 3; the polypropylene melt, the maleic anhydride grafted modified polypropylene melt, and the nylon 6 melt are extruded through the same melt co-extrusion die 4 at 240°C, cooled, and pulled to obtain a 3D printing wire 14 containing three layers of materials.

[0144] Comparative Example 1

[0145] The difference between this comparative example and Example 1 is that the 3D printing wire 14 is composed of only a core layer 13 and a skin layer 11 , and does not have an adhesive layer 12 .

[0146] Comparative Example 2

[0147] The difference between this comparative example and Example 2 is that the 3D printing wire 14 is composed of only a core layer 13 and a skin layer 11 , and does not have an adhesive layer 12 .

[0148] Comparative Example 3

[0149] The difference between this comparative example and Example 3 is that the 3D printing wire 14 is composed of only a core layer 13 and a skin layer 11 , and does not have an adhesive layer 12 .

[0150] Comparative Example 4

[0151] The difference between this comparative example and Example 4 is that the preparation conditions are different, as follows:

[0152] The polypropylene is melt-extruded at a temperature of 200°C in the first single-screw extruder 1, the maleic anhydride grafted modified polypropylene is melt-extruded at a temperature of 220°C in the second single-screw extruder 2, and nylon 6 is melt-extruded at a temperature of 260°C in the third single-screw extruder 3; the polypropylene melt, the maleic anhydride grafted modified polypropylene melt and the nylon 6 melt are extruded through the same die at 210°C, cooled, and pulled to obtain a 3D printing wire 14 containing three layers of materials.

[0153] Test example

[0154] The performance of the 3D printing wires obtained in Examples 1-4 and Comparative Examples 1-4 was compared, and the results are shown in Table 1. The tensile strength in the XY direction and the tensile strength in the Z direction were tested using GB / T1040-2018 and ISO 527:2012, the bending strength in the XY direction was tested using ISO178:2019 and GB / T 9341-2008, and the notched impact strength was tested using ISO 179-1:2023 and GB / T 1043.1-2008.

[0155] Table 1 Test results

[0156]

[0157]

[0158] It can be seen from Table 1 that the three-layer structure wire formed by the central layer, the adhesive layer and the skin layer can have better printability (such as stability, etc.) and functionality (such as strength, etc.) than the two-layer structure wire formed by only the central layer and the skin layer.

[0159] In summary, the present application creatively provides an adhesive layer between the central layer and the skin layer, which can effectively improve the bonding between the central layer material and the skin layer material, and solve the problem of balancing the printability and functionality of the homogeneous blended material. The preparation method of the 3D printing wire is simple, easy to operate, and can be industrially produced.

[0160] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A 3D printing wire, characterized in that: The 3D printing wire comprises a central layer, an adhesive layer and a skin layer arranged from inside to outside; The core layer, the skin layer and the adhesive layer are prepared from different polymer-based materials.

2. The 3D printing wire according to claim 1, characterized in that: The 3D printing wire comprises at least one of the following features: Feature 1: The chemical composition of the 3D printing wire is distributed in layers along the circumference of the wire; Feature 2: The volume fraction of the central layer is 1-98.9%, preferably 20-79%; Feature 3: The volume fraction of the adhesive layer is 0.01-20%, preferably 1-10%; Feature 4: The volume fraction of the epidermis is 1-98.9%, preferably 20-79%; Feature 5: The thickness of the adhesive layer is 1-500 μm; Feature 6: The raw material for preparing the adhesive layer is a material that can be at least partially fused with the raw material for preparing the core layer and the raw material for preparing the skin layer.

3. The 3D printing wire according to claim 1 or 2, characterized in that: The raw materials for preparing the central layer include at least one of polyolefins and copolymers of polyolefins; or, include at least one of polyamides and copolymers of polyamides; or, include at least one of polyesters and copolymers of polyesters; or, include at least one of polycarbonates and copolymers of polycarbonates; or, include polyoxymethylene and copolymers of polyoxymethylene; or, include at least one of polyphenylene ether and copolymers of polyphenylene ether; or, include at least one of polyphenylene sulfide and copolymers of polyphenylene sulfide; or, include at least one of polyetheretherketone and copolymers of polyetheretherketone; or, include at least one of polysulfone and copolymers of polysulfone; or, include at least one of liquid crystal polymer materials and copolymers of liquid crystal polymer materials.

4. The 3D printing wire according to claim 3, characterized in that: The raw material for preparing the central layer includes at least one of thermoplastic polyolefin and polyolefin elastomer.

5. The 3D printing wire according to claim 4, characterized in that: The thermoplastic polyolefin includes at least one of polyethylene, polypropylene, polymethylpentene and polybutene-1.

6. The 3D printing wire according to claim 4, characterized in that: The polyolefin elastomer includes at least one of polyisobutylene, ethylene propylene rubber and ethylene propylene diene monomer rubber.

7. The 3D printing wire according to claim 3, characterized in that: The polyamide includes at least one of nylon 6, nylon 6 elastomer, nylon 66, binary copolymer nylon 66 / 6, nylon 11, nylon 11 elastomer, nylon 12, nylon 12 elastomer, nylon 1010, nylon 1012 and nylon 610.

8. The 3D printing wire according to claim 3, characterized in that: The polyester includes at least one of polyethylene terephthalate, polybutylene terephthalate, and polyarylate.

9. The 3D printing wire according to claim 1 or 2, characterized in that: The raw materials for preparing the epidermis layer include at least one of polyolefins and copolymers of polyolefins; or, include at least one of polyamides and copolymers of polyamides; or, include at least one of polyesters and copolymers of polyesters; or, include at least one of polycarbonates and copolymers of polycarbonates; or, include polyoxymethylene and copolymers of polyoxymethylene; or, include at least one of polyphenylene ether and copolymers of polyphenylene ether; or, include at least one of polyphenylene sulfide and copolymers of polyphenylene sulfide; or, include at least one of polyetheretherketone and copolymers of polyetheretherketone; or, include at least one of polysulfone and copolymers of polysulfone; or, include at least one of liquid crystal polymer materials and copolymers of liquid crystal polymer materials.

10. The 3D printing wire according to claim 9, characterized in that: The raw material for preparing the skin layer includes at least one of thermoplastic polyolefin and polyolefin elastomer.

11. The 3D printing wire according to claim 10, characterized in that: The thermoplastic polyolefin includes at least one of polyethylene, polypropylene, polymethylpentene and polybutene-1.

12. The 3D printing wire according to claim 10, characterized in that: The polyolefin elastomer includes at least one of polyisobutylene, ethylene propylene rubber and ethylene propylene diene monomer rubber.

13. The 3D printing wire according to claim 9, characterized in that: The polyamide includes at least one of nylon 6, nylon 6 elastomer, nylon 66, binary copolymer nylon 66 / 6, nylon 11, nylon 11 elastomer, nylon 12, nylon 12 elastomer, nylon 1010, nylon 1012 and nylon 610.

14. The 3D printing wire according to claim 9, characterized in that: The polyester includes at least one of polyethylene terephthalate, polybutylene terephthalate, and polyarylate.

15. The 3D printing wire according to claim 1 or 2, characterized in that: The preparation material of the adhesive layer includes at least one of a polyolefin polymer grafted with polar molecules, a polyolefin polymer grafted with polar groups, and a copolymer-modified polyolefin polymer.

16. The 3D printing wire according to claim 15, characterized in that: The polar molecules include at least one of anhydrides, epoxies, acids, vinyl acetate, acrylates, methacrylates, and polyolefins.

17. The 3D printing wire according to claim 16, characterized in that: The acid anhydrides include maleic anhydride; and / or, the epoxy comprises glycidyl methacrylate; and / or, the acid comprises at least one of acrylic acid and methacrylic acid; And / or, the acrylic acid esters include at least one of ethyl acrylate and butyl acrylate; And / or, the methacrylates include at least one of methacrylate and methyl methacrylate; And / or, the polyolefin includes at least one of polyethylene, polypropylene, polystyrene, acrylonitrile-butadiene-styrene copolymer and polyolefin elastomer.

18. The 3D printing wire according to claim 1 or 2, characterized in that: The raw materials for preparing the central layer and the raw materials for preparing the skin layer are both polymer-based materials, and the raw materials for preparing the central layer and the raw materials for preparing the skin layer have different crystallization behaviors.

19. The 3D printing wire according to claim 18, characterized in that: The crystallization behavior includes at least one of crystallization rate, crystal morphology and crystallinity.

20. The 3D printing wire according to claim 19, characterized in that: The crystallization rate of the raw material for preparing the central layer is lower than the crystallization rate of the raw material for preparing the skin layer.

21. The 3D printing wire according to claim 19, characterized in that: The crystallinity of the raw material for preparing the central layer is lower than the crystallinity of the raw material for preparing the skin layer.

22. The 3D printing wire according to claim 21, characterized in that: The raw material for preparing the skin layer is a semi-crystalline polymer.

23. The 3D printing wire according to claim 18, characterized in that: The raw material for preparing the central layer is polycarbonate, the raw material for preparing the skin layer is high-density polyethylene, and the raw material for preparing the adhesive layer is maleic anhydride grafted polyethylene.

24. The 3D printing wire according to claim 1 or 2, characterized in that: The raw material for preparing the central layer and the raw material for preparing the skin layer are both polymer-based materials, and the glass transition temperature of the raw material for preparing the central layer is different from the glass transition temperature of the raw material for preparing the skin layer.

25. The 3D printing wire according to claim 24, characterized in that: The glass transition temperature of the raw material for preparing the core layer and the glass transition temperature of the raw material for preparing the skin layer are independently -80°C to -380°C.

26. The 3D printing wire according to claim 25, characterized in that: The difference between the glass transition temperature of the raw material for preparing the core layer and the glass transition temperature of the raw material for preparing the skin layer is 1°C to 300°C.

27. The 3D printing wire according to claim 24, characterized in that: The raw material for preparing the central layer is polycarbonate, the raw material for preparing the skin layer is acrylonitrile-butadiene-styrene copolymer, and the raw material for preparing the adhesive layer is maleic anhydride grafted acrylonitrile-butadiene-styrene copolymer.

28. The 3D printing wire according to claim 1 or 2, characterized in that: The raw material for preparing the central layer and the raw material for preparing the skin layer are both polymer-based materials, and the elastic tensile modulus of the raw material for preparing the central layer and the tensile elastic modulus of the raw material for preparing the skin layer are different.

29. The 3D printing wire according to claim 28, characterized in that: The elastic tensile modulus of the raw material for preparing the core layer and the elastic tensile modulus of the raw material for preparing the skin layer are both independently 1 MPa-10 GPa.

30. The 3D printing wire according to claim 29, characterized in that: The difference between the elastic tensile modulus of the raw material for preparing the central layer and the elastic tensile modulus of the raw material for preparing the skin layer is 1 MPa-5 GPa.

31. The 3D printing wire according to claim 28, characterized in that: The raw material for preparing the central layer is polylactic acid, the raw material for preparing the skin layer is thermoplastic polyurethane, and the raw material for preparing the adhesive layer is ethylene-acrylate-glycidyl ester.

32. A method for preparing a 3D printing wire according to any one of claims 1 to 31, characterized in that: The method comprises the following steps: extruding, cooling and pulling the raw materials for preparing the central layer, the raw materials for preparing the adhesive layer and the raw materials for preparing the epidermis layer to form 3D printing wire.

33. The preparation method according to claim 32, characterized in that: The raw materials for preparing the center layer, the raw materials for preparing the bonding layer and the raw materials for preparing the skin layer are melted in different single-screw extruders respectively to obtain a center layer melt, a bonding layer melt and a skin layer melt; the center layer melt, the bonding layer melt and the skin layer melt are extruded through the same die.

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