3D printing filament and preparation method therefor

Abstract

The present application belongs to the technical field of 3D printing filaments, and discloses a 3D printing filament and a preparation method therefor. The 3D printing filament comprises a center layer, an adhesive layer, and a skin layer which are arranged from inside to outside; the preparation raw materials of the center layer, the skin layer, and the adhesive layer are polymer-based materials that are different from one another. By providing the adhesive layer between the center layer and the skin layer, the bonding between the center layer material and the skin layer material can be effectively improved, solving the problem that it is difficult to balance printability and functionality in uniform blended materials. The preparation method therefor comprises the following steps: performing extrusion molding, cooling, and traction by combining preparation raw material of a center layer, preparation raw material of an adhesive layer, and preparation raw material of a skin layer, thereby forming a 3D printing filament. The method is simple, easy to operate, and suitable for industrialized production.

Description

A 3D printing filament and its preparation method

[0001] Cross-reference of related applications

[0002] This application claims priority to Chinese Patent Application No. 2024106776240, filed on May 29, 2024, entitled "A 3D Printing Filament and a Method for Preparing the Same", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of 3D printing filament technology, and more specifically, to a 3D printing filament and its preparation method. Background Technology

[0004] In extrusion 3D printing, fused filament fabrication (FFF) melts polymer filaments through heating and extrudes the melt from a nozzle, depositing it layer by layer onto a substrate to achieve 3D printing of objects. Due to the unique process characteristics of FFF 3D printing (such as significant non-steady-state conditions and complex thermal histories), this technology places high demands on the "printability" of materials. "Printability" broadly refers to the ability of a polymer material to be formed under FFF process conditions (evaluated through extrusion, deposition, fusion, sag, filament drawing, warpage, bridging, nozzle wear, etc.), or the processing window width while meeting forming requirements. Besides printability, the rapidly expanding application areas of FFF technology also place higher demands on the functionality of materials; functional design must be completed while ensuring printability, leading to greater complexity and challenges in the design of functional 3D printing materials compared to traditional polymer materials. For this reason, the lack of materials that combine printability and functionality remains a significant bottleneck limiting the wider application of FFF technology.

[0005] Melt blending modification is a mainstream modification technology for polymer materials in extrusion 3D printing. Its principle involves melting and blending multiple materials at a specific temperature, and then, under the combined action of a specific external force and temperature field, preparing a multiphase composite material. The core idea is to combine the strengths and compensate for the weaknesses of materials with different properties to create a composite material. However, in actual manufacturing processes, numerous problems make it difficult to achieve a balance between printability and functionality in 3D printing filaments based on melt blending modification technology.

[0006] Summary of the Invention

[0007] The purpose of this application is to provide a 3D printing filament and its preparation method to solve or improve the above-mentioned technical problems.

[0008] This application can be implemented as follows:

[0009] In a first aspect, this application provides a 3D printing filament, which includes a central layer, an adhesive layer and a skin layer arranged from the inside out;

[0010] The skin layer, the core layer, and the adhesive layer are prepared from different polymer-based materials.

[0011] In an optional implementation, the 3D printing filament includes at least one of the following features:

[0012] Feature 1: The chemical composition of 3D printing filament is distributed in layers along the radial circumference of the filament;

[0013] Feature 2: The volume fraction of the central layer is 1-98.9%;

[0014] Feature 3: The volume fraction of the adhesive layer is 0.01-20%;

[0015] Feature 4: The volume fraction of the epidermis ranges from 1% to 98.9%;

[0016] Feature 5: The thickness of the adhesive layer is 1-500μm;

[0017] Feature 6: The raw material for the adhesive layer is a material that can be at least partially fused with the raw materials for the core layer and the skin layer.

[0018] In an optional embodiment, the raw materials for preparing the central layer include at least one of polyolefins and copolymers of polyolefins.

[0019] In an optional embodiment, the raw materials for preparing the central layer include at least one of thermoplastic polyolefin and polyolefin elastomer.

[0020] In an optional embodiment, the thermoplastic polyolefin includes at least one of polyethylene, polypropylene, polymethylpentene, and polybutene-1.

[0021] In an optional embodiment, the polyolefin elastomer includes at least one of polyisobutylene, ethylene propylene rubber, and ethylene propylene diene monomer (EPDM).

[0022] In an optional embodiment, the raw materials for preparing the central layer include at least one of polyamide and copolymers of polyamide.

[0023] 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.

[0024] In an optional embodiment, the raw materials for preparing the central layer include at least one of polyester and copolymers of polyester.

[0025] In an optional embodiment, the polyester includes at least one of polylactic acid, polyethylene terephthalate, polybutylene terephthalate, and polyarylate.

[0026] In an optional embodiment, the raw materials for preparing the central layer include at least one of polycarbonate and copolymers of polycarbonate.

[0027] In an optional embodiment, the raw materials for preparing the central layer include polyoxymethylene and copolymers of polyoxymethylene.

[0028] In an optional embodiment, the raw materials for preparing the central layer include at least one of polyphenylene ether and copolymers of polyphenylene ether.

[0029] In an optional embodiment, the raw materials for preparing the central layer include at least one of polyphenylene sulfide and copolymers of polyphenylene sulfide.

[0030] In an optional embodiment, the raw materials for preparing the central layer include at least one of polyether ether ketone and copolymers of polyether ether ketone.

[0031] In an optional embodiment, the raw materials for preparing the central layer include at least one of polysulfone and copolymers of polysulfone.

[0032] In an optional embodiment, the raw materials for preparing the central layer include at least one of liquid crystal polymer materials and copolymers of liquid crystal polymer materials.

[0033] In an optional embodiment, the raw materials for preparing the central layer include at least one of thermoplastic elastomer, rubber-based soft material, and composite material with thermoplastic elastomer and rubber-based soft material as the matrix resin.

[0034] In optional embodiments, the thermoplastic elastomer includes one or more of the following: thermoplastic polyurethane elastomer, styrene-based block copolymer thermoplastic elastomer, polyolefin-based thermoplastic elastomer, polyamide-based elastomer, polyester-based elastomer, and composite materials with elastomer polymer materials as the matrix resin. The elastomer polymer material includes at least one of the following: thermoplastic polyurethane elastomer, styrene-based block copolymer thermoplastic elastomer, polyolefin-based thermoplastic elastomer, polyamide-based elastomer, and polyester-based elastomer.

[0035] In optional embodiments, the rubber-based soft material includes synthetic rubber composed of two or more of the following: natural rubber, styrene-butadiene rubber, ethylene propylene rubber, nitrile rubber, silicone rubber, and fluororubber; or, a composite material in which the rubber polymer material is a matrix resin, wherein the rubber polymer material includes at least one of the following: natural rubber, styrene-butadiene rubber, ethylene propylene rubber, nitrile rubber, silicone rubber, and fluororubber.

[0036] In an optional embodiment, the raw materials for preparing the skin layer include at least one of polyolefins and copolymers of polyolefins.

[0037] In an optional embodiment, the raw materials for preparing the skin layer include at least one of thermoplastic polyolefins and polyolefin elastomers.

[0038] In an optional embodiment, the thermoplastic polyolefin includes at least one of polyethylene, polypropylene, polymethylpentene, and polybutene-1.

[0039] In an optional embodiment, the polyolefin elastomer includes at least one of polyisobutylene, ethylene propylene rubber, and ethylene propylene diene monomer (EPDM).

[0040] In an optional embodiment, the raw materials for preparing the skin layer include at least one of polyamide and copolymers of polyamide.

[0041] 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.

[0042] In an optional embodiment, the raw materials for preparing the skin layer include at least one of polyester and copolymers of polyester.

[0043] In an optional embodiment, the polyester includes at least one of polylactic acid, polyethylene terephthalate, polybutylene terephthalate, and polyarylate.

[0044] In an optional embodiment, the raw materials for preparing the skin layer include at least one of polycarbonate and copolymers of polycarbonate.

[0045] In an optional embodiment, the raw materials for preparing the skin layer include polyoxymethylene and copolymers of polyoxymethylene.

[0046] In an optional embodiment, the raw materials for preparing the skin layer include at least one of polyphenylene ether and copolymers of polyphenylene ether.

[0047] In an optional embodiment, the raw materials for preparing the skin layer include at least one of polyphenylene sulfide and copolymers of polyphenylene sulfide.

[0048] In an optional embodiment, the raw materials for preparing the skin layer include at least one of polyetheretherketone and copolymers of polyetheretherketone.

[0049] In an optional embodiment, the raw materials for preparing the skin layer include at least one of polysulfone and copolymers of polysulfone.

[0050] In an optional embodiment, the raw materials for preparing the skin layer include at least one of liquid crystal polymer materials and copolymers of liquid crystal polymer materials.

[0051] In an optional embodiment, the raw materials for preparing the skin layer include at least one of thermoplastic elastomer, rubber-based soft material, and composite materials with thermoplastic elastomer and rubber-based soft material as the matrix resin.

[0052] In optional embodiments, the thermoplastic elastomer includes one or more of the following: thermoplastic polyurethane elastomer, styrene-based block copolymer thermoplastic elastomer, polyolefin-based thermoplastic elastomer, polyamide-based elastomer, polyester-based elastomer, and composite materials with elastomer polymer materials as the matrix resin. The elastomer polymer material includes at least one of the following: thermoplastic polyurethane elastomer, styrene-based block copolymer thermoplastic elastomer, polyolefin-based thermoplastic elastomer, polyamide-based elastomer, and polyester-based elastomer.

[0053] In optional embodiments, the rubber-based soft material includes synthetic rubber composed of two or more of the following: natural rubber, styrene-butadiene rubber, ethylene propylene rubber, nitrile rubber, silicone rubber, and fluororubber; or, a composite material in which the rubber polymer material is a matrix resin, wherein the rubber polymer material includes at least one of the following: natural rubber, styrene-butadiene rubber, ethylene propylene rubber, nitrile rubber, silicone rubber, and fluororubber.

[0054] In an optional embodiment, the adhesive layer is prepared from at least one of polar molecule-grafted polyolefin polymers, polar group-grafted polyolefin polymers, and copolymer-modified polyolefin polymers.

[0055] In optional embodiments, the polar molecules include at least one of acid anhydrides, epoxy compounds, acids, vinyl acetate, acrylates, methacrylates, and polyolefins.

[0056] In an optional embodiment, the anhydride class includes maleic anhydride;

[0057] And / or, epoxy compounds include glycidyl methacrylate;

[0058] And / or, acids include at least one of acrylic acid and methacrylic acid;

[0059] And / or, acrylates include at least one of ethyl acrylate and butyl acrylate;

[0060] And / or, methacrylates include at least one of methacrylates and methyl methacrylate;

[0061] And / or, polyolefins include at least one of polyethylene, polypropylene, polystyrene, acrylonitrile-butadiene-styrene copolymers, and polyolefin elastomers.

[0062] In an optional embodiment, the raw materials for preparing the central layer and the skin layer are both polymer-based materials, and the crystallization behaviors of the raw materials for preparing the central layer and the skin layer are different.

[0063] In an optional embodiment, the crystallization behavior includes at least one of crystallization rate, crystal morphology, and crystallinity.

[0064] In an optional embodiment, the crystallization rate of the raw materials for the central layer is lower than that of the raw materials for the skin layer.

[0065] In an optional embodiment, the crystallinity of the raw materials used to prepare the central layer is less than that of the raw materials used to prepare the skin layer.

[0066] In an optional embodiment, the raw material for preparing the skin layer is a semi-crystalline polymer.

[0067] In an optional embodiment, the raw material for preparing the core 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.

[0068] In an optional embodiment, the raw materials for preparing the central layer and the skin layer are both polymer-based materials, and the glass transition temperatures of the raw materials for preparing the central layer and the skin layer are different.

[0069] In an optional embodiment, 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 skin layer are both independently -80°C to -380°C.

[0070] In an optional embodiment, the difference between 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 is 1°C to 300°C.

[0071] 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.

[0072] In an optional embodiment, the raw materials for preparing the central layer and the skin layer are both polymer-based materials, and the tensile modulus of elasticity of the raw materials for preparing the central layer is different from that of the raw materials for preparing the skin layer.

[0073] In an optional embodiment, 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 are both independently 1 MPa-10 GPa.

[0074] In an optional embodiment, 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.

[0075] 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.

[0076] Secondly, this application provides a method for preparing 3D printing filament as described in any of the foregoing embodiments, comprising the following steps: extruding, cooling, and drawing together the raw materials for preparing the central layer, the raw materials for preparing the adhesive layer, and the raw materials for preparing the skin layer to form 3D printing filament.

[0077] In an optional embodiment, the raw materials for preparing the center layer, the adhesive layer, and 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 then extruded through the same die.

[0078] The beneficial effects of this application include:

[0079] The 3D printing filament provided in this application includes a central layer, an adhesive layer, and a skin layer arranged from the inside out; the raw materials for preparing the central layer, adhesive layer, and skin layer are different polymer-based materials. The above solution creatively improves the adhesion between the central layer and skin layer materials by setting an adhesive layer between them, thus solving the problem of balancing printability and functionality in homogeneous blended materials. Its preparation method includes the following steps: extruding, cooling, and drawing the raw materials for the central layer, adhesive layer, and skin layer together to form the 3D printing filament. This preparation method is simple, easy to operate, and suitable for industrial production. Attached Figure Description

[0080] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0081] Figure 1 is a schematic diagram of the structure of the 3D printing filament in an embodiment of this application;

[0082] Figure 2 is a schematic diagram of the equipment for preparing 3D printing filaments in the embodiments of this application.

[0083] Icons: 1-First single-screw extruder; 2-Second single-screw extruder; 3-Third single-screw extruder; 4-Melting co-extrusion die; 11-Skin layer; 12-Adhesive layer; 13-Core layer; 14-3D printing filament. Detailed Implementation

[0084] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0085] The following is a detailed description of the 3D printing filaments and their preparation method provided in this application.

[0086] The inventors creatively discovered that the reason why current melt blending modification technology for 3D printing filaments makes it difficult to achieve both printability and functionality may include: the dispersed multiphase structure in the filament during extrusion 3D printing using existing melt blending modification technology leads to weakened interlayer adhesion.

[0087] Based on this, this application creatively proposes a 3D printing filament comprising a central layer, an adhesive layer, and a skin layer arranged from the inside out.

[0088] The core layer, skin layer, and adhesive layer are prepared from different polymer-based materials. The adhesive layer is prepared from a material that can at least partially fuse with the materials used in the core layer and skin layer.

[0089] In this filament, the introduction of an 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 homogeneous blend material.

[0090] In some implementations, the chemical composition of the 3D printing filament can be distributed in layers along the radial circumference of the filament. This layered chemical composition allows for better preservation of the three-layer structure during melt extrusion, which, compared to simple blends of a central and outer skin layer, helps to solve the problem of balancing printability and functionality.

[0091] For reference, based on the above-mentioned layered distribution, if the adhesive layer uses a resin-based material, the incompatibility problem between the core layer and the skin layer material can be solved, avoiding interface defects in the wires and printed parts.

[0092] In the 3D printed filament of this 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%, 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%.

[0093] 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%, 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%.

[0094] The volume fraction of the epidermal layer can range from 1% to 98.9%, such as 1%, 2%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, or 98.9%, or any other value within the range of 1% to 98.9%. In some typical embodiments, the volume fraction of the epidermal layer is 20% to 79%.

[0095] The sum of the volume fractions of the central layer, the adhesive layer, and the epidermis is 100%.

[0096] 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, or any other value in the range of 1-500 μm.

[0097] By controlling the thickness of the adhesive layer within the aforementioned range, it is more beneficial to improve the adhesion between the core layer and the skin layer and the uniformity during the blending process.

[0098] In some embodiments of this application, the raw materials for preparing the central layer may include at least one of polyolefins and copolymers of polyolefins. Polyolefins are high molecular weight compounds formed by the addition polymerization of olefins. These organic polymers are typically formed by the polymerization of many identical or different simple olefin molecules (such as α-olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, etc., and certain cyclic olefins). In some embodiments, the raw materials for preparing the central layer may, for example, include at least one of thermoplastic polyolefins and polyolefin elastomers. Thermoplastic polyolefins may, exemplary but not limited to, include at least one of polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), and polybutene-1 (PB-1). Polyolefin elastomers (POE) may, exemplary but not limited to, include at least one of polyisobutylene (PIB), ethylene propylene rubber (EPR), and ethylene propylene diene monomer (EPDM). In this application, polyolefin material refers to a material based on a polymer obtained by polymerization or copolymerization of one or more olefins.

[0099] It should be noted that the aforementioned thermoplastic polyolefins refer to polymers with properties similar to plastics, while polyolefin elastomers refer to polymers with properties similar to rubber.

[0100] In some other embodiments of this application, the raw materials for preparing the central layer may include at least one of polyamide and copolymers of polyamide. The aforementioned polyamide (PA) is a polymer formed by polymerizing monomers containing carboxyl and amino groups through amide bonds. For reference, the aforementioned polyamide may also be referred to as nylon, which generally refers to a condensation polymer whose constituent units may be linked by amides. Exemplarily, the aforementioned 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 aforementioned nylon 6 elastomer is a block copolymer, with nylon 6 as the hard segment and polyether or polyester as the soft segment. Similarly, in the nylon 11 elastomer, nylon 11 is the hard segment, and polyether or polyester is the soft segment. In nylon 12 elastomers, nylon 12 is used as the hard segment, and polyether or polyester is used as the soft segment.

[0101] In other embodiments of this application, the raw materials for preparing the central layer may include at least one of polyester and copolymers of polyester. Polyester is a general term for polymers obtained by polycondensation of polyols and polyacids. In this application, polyester may, by way of example but not by way of limitation, include at least one of linear thermoplastic resins such as polylactic acid (PLA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyarylates.

[0102] In some other embodiments of this application, the raw materials for preparing the central layer may include at least one of polycarbonate and copolymers of polycarbonate. Polycarbonate (PC), also known as PC plastic, is a high molecular polymer containing carbonate groups in its molecular chain. According to the structure of the ester groups, it can be divided into various types such as aliphatic, aromatic, and aliphatic-aromatic.

[0103] In some other embodiments of this application, the raw materials for preparing the central layer may include at least one of polyoxymethylene (POM) and copolymers of POM. POM, also known as acetal resin, polyoxymethylene, or polyacetal, is a thermoplastic crystalline polymer.

[0104] In some other embodiments of this application, the raw materials for preparing the central layer may include at least one of polyphenylene ether and copolymers of polyphenylene ether. Polyphenylene ether (PPE) is a high-temperature thermoplastic, also known as polyoxyethylene (PPO), which is a non-crystalline thermoplastic polymer.

[0105] In some other embodiments of this application, the raw materials for preparing the central layer may include at least one of polyphenylene sulfide (PPS) and copolymers of PPS. PPS is a polymer containing repeating p-phenylene sulfide structural units in its molecule.

[0106] In some other embodiments of this application, the raw materials for preparing the central layer include at least one of polyetheretherketone (PEEK) and copolymers of PEEK. PEEK is a linear aromatic polymer compound with the constituent unit being oxy-p-phenylene-carbonyl-p-phenylene, and is a semi-crystalline thermoplastic.

[0107] In some other embodiments of this application, the raw materials for preparing the central layer may include at least one of polysulfone and copolymers of polysulfone.

[0108] In some other embodiments of this application, the raw materials for preparing the central layer may include at least one of liquid crystal polymer materials and copolymers of liquid crystal polymer materials. Liquid crystal polymers, also known as liquid crystal polymers (LCPs), are a new type of polymer material that generally transforms into liquid crystal form under certain heating conditions.

[0109] In some other embodiments of this application, the raw materials for preparing the central layer include at least one of thermoplastic elastomer, rubber-based soft material, and composite material of thermoplastic elastomer and rubber-based soft material as matrix resin.

[0110] In some other embodiments of this application, the thermoplastic elastomer includes one or more of thermoplastic polyurethane elastomer (TPU), styrene-based block copolymer thermoplastic elastomer (SBS), polyolefin-based thermoplastic elastomer (POE), polyamide-based elastomer (TPAE), polyester-based elastomer (TPEE), and composite materials with an elastomer polymer material as the matrix resin. The elastomer polymer material includes at least one of thermoplastic polyurethane elastomer (TPU), styrene-based block copolymer thermoplastic elastomer (SBS), polyolefin-based thermoplastic elastomer (POE), polyamide-based elastomer (TPAE), and polyester-based elastomer (TPEE).

[0111] In some other embodiments of this application, the rubber-based soft material includes synthetic rubber composed of two or more of the following: natural rubber, styrene-butadiene rubber, ethylene propylene rubber, nitrile rubber, silicone rubber, and fluororubber; or, the rubber polymer material is a composite material with a matrix resin, wherein the rubber polymer material includes at least one of the following: natural rubber, styrene-butadiene rubber, ethylene propylene rubber, nitrile rubber, silicone rubber, and fluororubber.

[0112] In this application, the raw materials for preparing the skin layer may also include at least one of polyolefins and copolymers of polyolefins, or at least one of thermoplastic polyolefins and polyolefin elastomers, or at least one of polyamides and copolymers of polyamides, or at least one of polyesters and copolymers of polyesters, or at least one of polycarbonate and copolymers of polycarbonate, or at least one of polyoxymethylene and copolymers of polyoxymethylene; or at least one of polyphenylene ether and copolymers of polyphenylene ether, or at least one of polyphenylene sulfide and copolymers of polyphenylene sulfide, or at least one of polyetheretherketone and copolymers of polyetheretherketone, or at least one of polysulfone and copolymers of polysulfone, or at least one of liquid crystal polymers and copolymers of liquid crystal polymers, or at least one of thermoplastic elastomers, rubber-like soft materials, and composite materials with thermoplastic elastomers and rubber-like soft materials as the matrix resin.

[0113] Thermoplastic polyolefins may also include at least one of polyethylene, polypropylene, polymethylpentene, and polybutene-1. Polyolefin elastomers may also include at least one of polyisobutylene, ethylene propylene diene monomer (EPDM), and EPDM. Polyamides 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.

[0114] In some other embodiments of this application, the thermoplastic elastomer includes one or more of thermoplastic polyurethane elastomer (TPU), styrene-based block copolymer thermoplastic elastomer (SBS), polyolefin-based thermoplastic elastomer (POE), polyamide-based elastomer (TPAE), polyester-based elastomer (TPEE), and composite materials with an elastomer polymer material as the matrix resin. The elastomer polymer material includes at least one of thermoplastic polyurethane elastomer (TPU), styrene-based block copolymer thermoplastic elastomer (SBS), polyolefin-based thermoplastic elastomer (POE), polyamide-based elastomer (TPAE), and polyester-based elastomer (TPEE).

[0115] In some other embodiments of this application, the rubber-based soft material includes synthetic rubber composed of two or more of the following: natural rubber, styrene-butadiene rubber, ethylene propylene rubber, nitrile rubber, silicone rubber, and fluororubber; or, the rubber polymer material is a composite material with a matrix resin, wherein the rubber polymer material includes at least one of the following: natural rubber, styrene-butadiene rubber, ethylene propylene rubber, nitrile rubber, silicone rubber, and fluororubber.

[0116] In this application, the material used to prepare the adhesive layer may include at least one of polar molecule-grafted polyolefin polymers, polar group-grafted polyolefin polymers, and copolymer-modified polyolefin polymers.

[0117] For reference, polar molecules may, by way of example but not limitation, include at least one of acid anhydrides, epoxy compounds, acids, vinyl acetate, acrylates, methacrylates, and polyolefins. Among them, acid anhydrides may, by way of example but not limitation, include maleic anhydride (MA). Epoxy compounds may, by way of example but not limitation, include glycidyl methacrylate (GMA). Acids may, by way of example but not limitation, include at least one of acrylic acid (AA) and methacrylic acid (MAA). Acrylates may, by way of example but not limitation, include at least one of ethyl acrylate and butyl acrylate. Methacrylates may, by way of example but not limitation, include at least one of methacrylate and methyl methacrylate. Polyolefins may, by way of example but not limitation, include at least one of polyethylene (PE), polypropylene (PP), polystyrene (PS), acrylonitrile-butadiene-styrene copolymer (ABS), and polyolefin elastomer (POE).

[0118] The aforementioned adhesive layer is mainly configured to bond the materials used in the core layer and the epidermis. The raw materials for preparing the adhesive layer are compatible with the raw materials for preparing the core layer and the epidermis.

[0119] In some typical embodiments, the raw materials for preparing the central layer and the skin layer are both polymer-based materials, and the crystallization behaviors of the raw materials for preparing the central layer and the skin layer are different. The crystallization behavior may, by way of example but not in a limiting sense, include at least one of crystallization rate, crystal morphology, and crystallinity.

[0120] For example, the crystallization rate of the raw material for the central layer is lower than that of the raw material for the skin layer. Alternatively, the crystallinity of the raw material for the central layer is lower than that of the raw material for the skin layer. In some optional embodiments, the raw material for the skin layer is a semi-crystalline polymer.

[0121] It should be noted that crystallization is the process by which polymer molecular chains arrange themselves to form ordered regions. If the crystalline regions of a polymer are too dense, the polymer printout is prone to uneven deformation during printing, leading to warping and making it difficult to guarantee dimensional accuracy. By using an amorphous polymer or a polymer with a slow crystallization rate as the core layer, and a semi-crystalline polymer with a faster crystallization rate or higher crystallinity as the skin layer, the polymer in the core layer sets first during printing. When the polymer in the skin layer crystallizes, the polymer material in the core layer, thanks to the adhesion layer, can suppress the deformation caused by the crystallization of the polymer in the skin layer. The resulting semi-crystalline 3D printing material exhibits better warping resistance during printing.

[0122] As an example, the raw material for preparing the core layer can be polycarbonate, the raw material for preparing the skin layer can be high-density polyethylene, and the raw material for preparing the adhesive layer can be maleic anhydride-grafted polyethylene.

[0123] In some other typical embodiments, the raw materials for preparing the central layer and the skin layer are both polymer-based materials, and the glass transition temperatures of the raw materials for preparing the central layer and the skin layer are different. For example, the raw material for preparing the central layer may be a high-Tg material and the raw material for preparing the skin layer may be a low-Tg material; or, the raw material for preparing the central layer may be a low-Tg material and the raw material for preparing the skin layer may be a high-Tg material.

[0124] The glass transition temperature (Tg) refers to the temperature at which a glassy material can reversibly transition between the glassy and elastic states. The glass transition temperature (Tg) of polymer materials is one of the characteristic temperatures of polymers, corresponding to the temperature at which molecular chain segments begin to move during the heating process. There are various methods for measuring it; that is, the glass transition temperature can be determined by measuring the changes in physical properties during the glass transition process of the polymer material. Exemplarily, the measurement methods typically include four types: volume change (dilatational method), thermodynamic properties (differential thermal analysis (DTA) and differential scanning calorimetry (DSC), mechanical property changes (thermomechanical method, stress relaxation method, and dynamic mechanical relaxation method (DMA), and electromagnetic effects (dielectric relaxation method). Tg values ​​measured by different testing methods differ and are not generally comparable. The Tg values ​​described in this application are comparisons of Tg values ​​under the same testing methods and conditions.

[0125] For example, the glass transition temperature of the raw materials for the central layer and the glass transition temperature of the raw materials for the skin layer are both independently -80°C to -380°C (e.g., -80°C, -100°C, -150°C, -200°C, -250°C, -300°C, -350°C, or -380°C). Preferably, the difference between the glass transition temperature of the raw materials for the central layer and the glass transition temperature of the raw materials for the skin layer is 1°C to 300°C (e.g., 1°C, 2°C, 5°C, 10°C, 50°C, 100°C, 150°C, 200°C, 250°C, or 300°C).

[0126] By using materials with different glass transition temperatures as the raw materials for the core layer and the skin layer, the resulting 3D printing material can have the following characteristics: while obtaining high heat resistance, the material maintains good printability, such as excellent interlayer properties and resistance to warping. In addition, it can also obtain excellent comprehensive mechanical properties, including better tensile strength, flexural strength and notched impact strength.

[0127] As an example, the raw material for preparing the core layer can be polycarbonate, the raw material for preparing the skin layer can be acrylonitrile-butadiene-styrene copolymer, and the raw material for preparing the adhesive layer can be maleic anhydride-grafted acrylonitrile-butadiene-styrene copolymer.

[0128] In some other typical embodiments, both the raw materials for the core layer and the skin layer are polymer-based materials, and the tensile modulus of the raw materials for the core layer and the skin layer are different. For example, the tensile modulus of the raw materials for the core layer may be greater than that of the raw materials for the skin layer (which is beneficial for improving interlayer toughness and obtaining a rigid-toughness balanced material with high overall stiffness and excellent interlayer toughness); or, the tensile modulus of the raw materials for the core layer may be less than that of the raw materials for the skin layer.

[0129] The tensile modulus of elasticity of polymer materials is an important method and performance parameter for characterizing the rigidity of polymer materials. It is measured by tensile testing of standard specimens. The specimen size and test conditions will affect the test results to a certain extent. In this application, the relative magnitude of the tensile modulus of elasticity of polymer materials is compared using the same test method standard, specimen 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.

[0130] The tensile modulus of a solid material characterizes its stiffness and mechanical properties. It is defined as the ratio of tensile stress (per unit area) to strain (relative deformation) during elastic deformation. In some cases, the tensile modulus can be configured to assess the stiffness of a material; in other words, the expected deformation (elasticity) of the material under a specific load. The higher the tensile modulus, the more force is required to deform it. 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 under tension. In some cases, the value of the tensile modulus is the ratio of the force required to stretch the material per unit length along its central axis to its cross-sectional area. In applications, the formula for calculating the tensile modulus is: Tensile modulus (N / (m×m)) = f / S (N / (m×m)); where f represents the required force, S represents the cross-sectional area of ​​the material, and N represents the required force.

[0131] For example, the elastic tensile modulus of the raw materials for the central layer and the raw materials for the skin layer are both independently 1 MPa-10 GPa (e.g., 1 MPa, 5 MPa, 10 MPa, 50 MPa, 100 MPa, 500 MPa, 1 GPa, 2 GPa, 5 GPa, 8 GPa, or 10 GPa, etc.). Preferably, the difference between the elastic tensile modulus of the raw materials for the central layer and the raw materials for the skin layer is 1 MPa-5 GPa.

[0132] As an example, the raw material for preparing the core layer can be polylactic acid, the raw material for preparing the skin layer can be thermoplastic polyurethane, and the raw material for preparing the adhesive layer can be ethylene-acrylate-glycidyl ester.

[0133] By using materials with different elastic tensile moduli as raw materials for the preparation of the core layer and the skin layer, the overall rigidity of the soft filament can be improved, the extrusion and conveying properties of the soft elastomer material during printing can be improved, and problems such as filament slippage can be solved. This, in turn, improves the smoothness of filament conveying in the print head part of 3D printing and thus helps to improve printing efficiency.

[0134] In addition, this application also provides a method for preparing the above-mentioned 3D printing filament, which may include the following steps: extruding, cooling and drawing together 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 filament.

[0135] For reference, the raw materials for the center layer, the adhesive layer, and the skin layer can be placed in different melt extrusion devices (single-screw extruders). By metering and controlling the extrusion flow rate, the melts of the three materials are extruded through the same die, and after cooling and traction, they are formed into 3D printed filaments, ultimately yielding a structural filament containing three layers of materials. Alternatively, this can be understood as follows: the raw materials for the center layer, the adhesive layer, and the skin layer are melted separately in different single-screw extruders to obtain the center layer melt, the adhesive layer melt, and the skin layer melt; these three melts are then extruded through the same die.

[0136] To ensure good fusion of the bonding layer material with the core and skin layers, the temperature and rotation speed of the melt extrusion unit can be adjusted to ensure stable melting and extrusion feeding of all three materials, maintaining consistent volumetric flow rates throughout continuous production. Furthermore, the temperature of the die runner also ensures that the three materials converge in the molten state, resulting in consistent melt flow rates and preventing turbulence or disturbances during melt flow. This ensures that all three materials can be stably extruded as a viscous melt at the die set temperature.

[0137] For reference, taking polypropylene as the raw material for the center layer, nylon 6 as the raw material for the skin layer, and maleic anhydride-grafted modified polypropylene as the raw material for the adhesive layer, the raw materials for the center layer are melted at 210-230℃, the raw materials for the skin layer are melted at 245-270℃, the raw materials for the adhesive layer are melted at 215-235℃, and the temperature of the die is 235-255℃.

[0138] 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 raw material for the preparation of the center layer), the melt extrusion temperature of the second single-screw extruder is 260°C (corresponding to the raw material for the preparation of the adhesive layer), the melt extrusion temperature of the third single-screw extruder is 230°C (corresponding to the raw material for the preparation of the skin layer), and the die temperature is 240°C.

[0139] In conclusion, the method for preparing 3D printing filaments provided in this application is simple, easy to operate, and has controllable conditions, and is applicable to industrial production. The resulting 3D printing filaments can effectively balance printability and functionality.

[0140] The features and performance of this application will be further described in detail below with reference to the embodiments.

[0141] Example 1

[0142] This embodiment provides a 3D printing filament 14, as shown in Figure 1. Its chemical composition is distributed in layers along the circumference of the filament, including a central layer 13, an adhesive layer 12, and a skin layer 11 from the inside to the outside.

[0143] The core layer 13 is made of polycarbonate (PC), the skin layer 11 is made of high-density polyethylene (HDPE), and the adhesive layer 12 is made of maleic anhydride-grafted polyethylene (MA-PE). The core layer 13 has a volume fraction of 55% in the 3D printing filament 14, the adhesive layer 12 has a volume fraction of 2% in the 3D printing filament 14, the skin layer 11 has a volume fraction of 43% in the 3D printing filament 14, and the adhesive layer 12 has a thickness of 12 μm.

[0144] The preparation process of the 3D printed filament 14 includes: melting and extruding polycarbonate in a first single-screw extruder 1 (referring to Figure 2) at a temperature of 260°C; melting and extruding maleic anhydride-grafted polyethylene in a second single-screw extruder 2 at a temperature of 210°C; melting and extruding high-density polyethylene in a third single-screw extruder 3 at a temperature of 215°C; extruding the polycarbonate melt, maleic anhydride-grafted polyethylene melt, and high-density polyethylene melt through the same melt co-extrusion die 4 at a temperature of 235°C; cooling and drawing to obtain the 3D printed filament 14 containing three layers of material.

[0145] Example 2

[0146] This embodiment provides a 3D printing filament 14, as shown in Figure 1. Its chemical composition is distributed in layers along the circumference of the filament, including a central layer 13, an adhesive layer 12, and a skin layer 11 from the inside to the outside.

[0147] The core layer 13 is made of polycarbonate (PC), the skin layer 11 is made of acrylonitrile-butadiene-styrene copolymer (ABS), and the adhesive layer 12 is made of maleic anhydride-grafted ABS (MA-ABS). The core layer 13 has a volume fraction of 70% in the 3D printing filament 14, the adhesive layer 12 has a volume fraction of 5% in the 3D printing filament 14, the skin layer 11 has a volume fraction of 25% in the 3D printing filament 14, and the adhesive layer 12 has a thickness of 26 μm.

[0148] The preparation process of the 3D printed filament 14 includes: melting and extruding polycarbonate in a first single-screw extruder 1 (referring to Figure 2) at a temperature of 260°C; melting and extruding maleic anhydride-grafted ABS in a second single-screw extruder 2 at a temperature of 255°C; melting and extruding acrylonitrile-butadiene-styrene copolymer in a third single-screw extruder 3 at a temperature of 250°C; extruding the polycarbonate melt, maleic anhydride-grafted ABS melt, and acrylonitrile-butadiene-styrene copolymer melt through the same melt co-extrusion die 4 at 250°C, cooling, and drawing to obtain the 3D printed filament 14 containing 3 layers of material.

[0149] Example 3

[0150] This embodiment provides a 3D printing filament 14, as shown in Figure 1. Its chemical composition is distributed in layers along the circumference of the filament, including a central layer 13, an adhesive layer 12, and a skin layer 11 from the inside to the outside.

[0151] The core layer 13 is made of polylactic acid (PLA), the skin layer 11 is made of thermoplastic polyurethane (TPU), and the adhesive layer 12 is made of ethylene-acrylate-glycidyl ester (EGMA). The core layer 13 has a volume fraction of 45% in the 3D printing filament 14, the adhesive layer 12 has a volume fraction of 3% in the 3D printing filament 14, the skin layer 11 has a volume fraction of 52% in the 3D printing filament 14, and the adhesive layer 12 has a thickness of 20 μm.

[0152] The preparation process of the 3D printed filament 14 includes: melting and extruding polylactic acid in a first single-screw extruder 1 (referring to Figure 2) at a temperature of 210°C; melting and extruding ethylene-acrylate-glycidyl ester in a second single-screw extruder 2 at a temperature of 190°C; melting and extruding thermoplastic polyurethane in a third single-screw extruder 3 at a temperature of 215°C; extruding the polylactic acid melt, ethylene-acrylate-glycidyl ester melt, and thermoplastic polyurethane melt through the same melt co-extrusion die 4 at 210°C, cooling, and drawing to obtain the 3D printed filament 14 containing three layers of material.

[0153] Example 4

[0154] This embodiment provides a 3D printing filament 14, as shown in Figure 1. Its chemical composition is distributed in layers along the circumference of the filament, including a central layer 13, an adhesive layer 12, and a skin layer 11 from the inside to the outside.

[0155] The core layer 13 is made of polypropylene (PP), the skin layer 11 is made of nylon 6 (PA6), and the adhesive layer 12 is made of maleic anhydride-grafted modified polypropylene (MA-PP). The core layer 13 has a volume fraction of 70% in the 3D printing filament 14, the adhesive layer 12 has a volume fraction of 6% in the 3D printing filament 14, the skin layer 11 has a volume fraction of 24% in the 3D printing filament 14, and the adhesive layer 12 has a thickness of 30 μm.

[0156] The preparation process of the 3D printing filament 14 includes: melting and extruding polypropylene in a first single-screw extruder 1 (referring to Figure 2) at a temperature of 220°C; melting and extruding maleic anhydride-grafted modified polypropylene in a second single-screw extruder 2 at a temperature of 230°C; melting and extruding nylon 6 in a third single-screw extruder 3 at a temperature of 260°C; extruding the polypropylene melt, the maleic anhydride-grafted modified polypropylene melt, and the nylon 6 melt through the same melt co-extrusion die 4 at a temperature of 240°C; cooling and drawing to obtain the 3D printing filament 14 containing three layers of material.

[0157] Comparative Example 1

[0158] The difference between this comparative example and Example 1 is that the 3D printed filament 14 consists only of a central layer 13 and a skin layer 11, and does not have an adhesive layer 12.

[0159] Comparative Example 2

[0160] The difference between this comparative example and Example 2 is that the 3D printed filament 14 consists only of a central layer 13 and a skin layer 11, and does not have an adhesive layer 12.

[0161] Comparative Example 3

[0162] The difference between this comparative example and Example 3 is that the 3D printed filament 14 consists only of a central layer 13 and a skin layer 11, and does not have an adhesive layer 12.

[0163] Comparative Example 4

[0164] The difference between this comparative example and Example 4 lies in the different preparation conditions, as detailed below:

[0165] Polypropylene is melt-extruded in a first single-screw extruder 1 at a temperature of 200°C, maleic anhydride-grafted modified polypropylene is melt-extruded in a second single-screw extruder 2 at a temperature of 220°C, and nylon 6 is melt-extruded in a third single-screw extruder 3 at a temperature of 260°C. The polypropylene melt, maleic anhydride-grafted modified polypropylene melt, and nylon 6 melt are extruded through the same die at 210°C, cooled, and drawn to obtain a 3D printing filament 14 containing three layers of material.

[0166] Test case

[0167] The performance of the 3D printing filaments 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 and Z directions was tested according to GB / T 1040-2018 and ISO 527:2012; the flexural strength in the XY directions was tested according to ISO 178:2019 and GB / T 9341-2008; and the notched impact strength was tested according to ISO 179-1:2023 and GB / T 1043.1-2008.

[0168] Table 1 Test Results

[0169] As can be seen from Table 1, filaments with a three-layer structure consisting of a central layer, an adhesive layer, and a skin layer have better printability (such as stability) and functionality (such as strength) than filaments with a two-layer structure consisting of only a central layer and a skin layer.

[0170] In summary, this application creatively improves the adhesion between the core layer and the skin layer by setting an adhesive layer between the core layer and the skin layer, thus solving the problem of the difficulty in balancing printability and functionality in homogeneous blended materials. The preparation method of this 3D printing filament is simple, easy to operate, and can be industrialized.

[0171] The above are merely optional embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application. Industrial applicability

[0172] Using the above scheme, the 3D printing filament includes a central layer, an adhesive layer, and a skin layer arranged from the inside out; the raw materials for preparing the central layer, adhesive layer, and skin layer are different polymer-based materials. By setting an adhesive layer between the central layer and the skin layer, the adhesion between the central layer material and the skin layer material can be effectively improved, solving the problem of difficulty in balancing printability and functionality in homogeneous blended materials. The preparation method includes the following steps: extruding, cooling, and drawing the raw materials for the central layer, adhesive layer, and skin layer together to form the 3D printing filament. This preparation method is simple, easy to operate, and suitable for industrial production.

Claims

1. A 3D printing filament, characterized in that, The 3D printing filament includes a central layer, an adhesive layer, and a skin layer arranged from the inside out; The core layer, the skin layer, and the adhesive layer are prepared from different polymer-based materials.

2. The 3D printing filament according to claim 1, characterized in that, The 3D printing filament includes at least one of the following characteristics: Feature 1: The chemical composition of the 3D printing filament is distributed in layers along the radial direction of the circumference of the filament; Feature 2: The volume fraction of the central layer is 1-98.9%; Feature 3: The volume fraction of the adhesive layer is 0.01-20%; Feature 4: The volume fraction of the epidermal layer is 1-98.9%; 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 central layer and the raw material for preparing the epidermal layer.

3. The 3D printing filament 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, at least one of polyamides and copolymers of polyamides; or, at least one of polyesters and copolymers of polyesters; or, at least one of polycarbonate and copolymers of polycarbonate; or, at least one of polyoxymethylene and copolymers of polyoxymethylene; or, at least one of polyphenylene ether and copolymers of polyphenylene ether; or, at least one of polyphenylene sulfide and copolymers of polyphenylene sulfide; or, at least one of polyetheretherketone and copolymers of polyetheretherketone; or, at least one of polysulfone and copolymers of polysulfone; or, at least one of liquid crystal polymers and copolymers of liquid crystal polymers.

4. The 3D printing filament according to claim 3, characterized in that, The raw materials for preparing the central layer include at least one of thermoplastic polyolefin and polyolefin elastomer; or, at least one of thermoplastic elastomer, rubber-based soft material, and composite material in which the thermoplastic elastomer and rubber-based soft material are used as the matrix resin.

5. The 3D printing filament 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 filament according to claim 4, characterized in that, The polyolefin elastomer includes at least one of polyisobutylene, ethylene propylene rubber, and ethylene propylene diene monomer (EPDM).

7. The 3D printing filament 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 filament according to claim 3, characterized in that, The polyester includes at least one of polylactic acid, polyethylene terephthalate, polybutylene terephthalate, and polyarylate.

9. The 3D printing filament according to claim 1 or 2, characterized in that, The raw materials for preparing the skin layer include at least one of polyolefins and copolymers of polyolefins; or, at least one of polyamides and copolymers of polyamides; or, at least one of polyesters and copolymers of polyesters; or, at least one of polycarbonate and copolymers of polycarbonate; or, at least one of polyoxymethylene and copolymers of polyoxymethylene; or, at least one of polyphenylene ether and copolymers of polyphenylene ether; or, at least one of polyphenylene sulfide and copolymers of polyphenylene sulfide; or, at least one of polyetheretherketone and copolymers of polyetheretherketone; or, at least one of polysulfone and copolymers of polysulfone; or, at least one of liquid crystal polymers and copolymers of liquid crystal polymers; or, at least one of thermoplastic elastomers, rubber-like soft materials, and composite materials in which the thermoplastic elastomer and the rubber-like soft material are used as the matrix resin.

10. The 3D printing filament according to claim 9, characterized in that, The raw materials for preparing the skin layer include at least one of thermoplastic polyolefins and polyolefin elastomers.

11. The 3D printing filament 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 filament according to claim 10, characterized in that, The polyolefin elastomer includes at least one of polyisobutylene, ethylene propylene rubber, and ethylene propylene diene monomer (EPDM).

13. The 3D printing filament 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 filament according to claim 9, characterized in that, The polyester includes at least one of polylactic acid, polyethylene terephthalate, polybutylene terephthalate, and polyarylate.

15. The 3D printing filament according to claim 1 or 2, characterized in that, The adhesive layer is prepared from at least one of the following materials: polar molecule-grafted polyolefin polymers, polar group-grafted polyolefin polymers, and copolymer-modified polyolefin polymers.

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

17. The 3D printing filament according to claim 16, characterized in that, The acid anhydrides include maleic anhydride; And / or, the epoxy class includes glycidyl methacrylate; And / or, the acids include at least one of acrylic acid and methacrylic acid; And / or, the acrylates include at least one of ethyl acrylate and butyl acrylate; And / or, the methacrylates include at least one of methacrylates 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 filament according to claim 1 or 2, characterized in that, Both the raw materials for preparing the central layer and the raw materials for preparing the skin layer are polymer-based materials, and the crystallization behaviors of the raw materials for preparing the central layer and the raw materials for preparing the skin layer are different.

19. The 3D printing filament 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 filament according to claim 19, characterized in that, The crystallization rate of the raw materials used to prepare the central layer is lower than that of the raw materials used to prepare the skin layer.

21. The 3D printing filament according to claim 19, characterized in that, The crystallinity of the raw materials used to prepare the central layer is less than that of the raw materials used to prepare the epidermal layer.

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

23. The 3D printing filament according to claim 18, characterized in that, The core layer is made of polycarbonate, the skin layer is made of high-density polyethylene, and the adhesive layer is made of maleic anhydride-grafted polyethylene.

24. The 3D printing filament according to claim 1 or 2, characterized in that, Both the raw materials for preparing the central layer and the raw materials for preparing the skin layer are polymer-based materials, and the glass transition temperatures of the raw materials for preparing the central layer and the raw materials for preparing the skin layer are different.

25. The 3D printing filament according to claim 24, characterized in that, The glass transition temperature of the raw materials for the preparation of the central layer and the glass transition temperature of the raw materials for the preparation of the skin layer are both independently -80°C to -380°C.

26. The 3D printing filament according to claim 25, characterized in that, The difference between the glass transition temperature of the raw material used to prepare the central layer and the glass transition temperature of the raw material used to prepare the skin layer is 1°C to 300°C.

27. The 3D printing filament 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 filament according to claim 1 or 2, characterized in that, Both the raw materials for the preparation of the central layer and the raw materials for the preparation of the skin layer are polymer-based materials, and the tensile modulus of elasticity of the raw materials for the preparation of the central layer is different from that of the raw materials for the preparation of the skin layer.

29. The 3D printing filament according to claim 28, characterized in that, The elastic tensile modulus of the raw materials used to prepare the central layer and the elastic tensile modulus of the raw materials used to prepare the skin layer are both independently 1 MPa-10 GPa.

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

31. The 3D printing filament according to claim 28, characterized in that, The core layer is made from polylactic acid, the skin layer is made from thermoplastic polyurethane, and the adhesive layer is made from ethylene-acrylate-glycidyl ester.

32. A method for preparing 3D printing filament as described in any one of claims 1-31, characterized in that, The process includes the following steps: extruding, cooling, and drawing the raw materials for the preparation of the central layer, the adhesive layer, and the skin layer together to form a 3D printed filament.

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

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