Extrusion-type 3D printing filament, and preparation method therefor and use thereof

Abstract

The present application provides an extrusion-type 3D printing filament and a preparation method therefor. The filament comprises a first material and a second material, and the first material and the second material each have a radial gradient distribution. The radial gradient distributions in the chemical composition solve the problem of interfacial incompatibility of the materials, and avoid interfacial defects in the filament and printed objects; during the melt extrusion process, laminar flow enables the radial gradient distribution structure in composition to be kept, and the radial gradient distribution structure is beneficial to improving rheological stability.

Description

Extrusion 3D Printing Filaments, Their Preparation Methods and Applications Technical Field

[0001] This application relates to the development and preparation technology of 3D printing materials, and in particular to an extruded 3D printing filament, its preparation method and application. Background Technology

[0002] In extrusion 3D printing, fused filament fabrication (FFF) melts polymer filaments through heating and extrudes the melt from a nozzle, gradually depositing it onto a substrate to achieve 3D printing of objects. Due to the unique process characteristics of FFF 3D printing, such as numerous non-steady states and complex thermal histories, this technology places high demands on the "printability" of materials. "Printability" 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 width of the processing window 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.

[0003] For the aforementioned industry challenges, conventional material modification techniques, with melt blending as the core method, are insufficient to provide systematic solutions. Melt blending is the mainstream modification technology for polymer materials in extrusion 3D printing. Its principle involves melting and blending multiple materials at a specific temperature, and under the combined action of a certain external force and temperature field, preparing a multiphase composite material. The core idea is to combine the strengths and weaknesses of various materials to create a composite material. However, existing melt blending modification technologies still have some common problems in the application of extrusion 3D printing. For example, the dispersed multiphase structure in the filament weakens the interlayer adhesion during extrusion 3D printing; furthermore, there is often a conflict between printability and end-useability, which general modification techniques cannot deeply optimize; and finally, the high rigidity of polymer materials, especially with high composite filler content, leads to significant brittleness in the filament, hindering its use.

[0004] Therefore, to address the aforementioned technical issues, it is necessary to further improve 3D printing filaments based on melt blending modification technology in order to achieve a balance between printability and functionality.

[0005] Summary of the Invention

[0006] This application uses 3D printing filaments with a radial gradient distribution in chemical composition, which solves many technical problems that make it difficult to balance printability and functionality, such as weak interlayer adhesion and high brittleness of materials with high fiber content.

[0007] Therefore, the embodiments of this application adopt the following technical solutions.

[0008] In a first aspect, embodiments of this application provide an extruded 3D printing filament comprising: a first material; and a second material, wherein the first material and the second material each have a radial gradient distribution.

[0009] In some embodiments, the mass fraction of the first material gradually decreases radially from the inside to the outside; the mass fraction of the second material gradually increases radially from the inside to the outside; and the sum of the mass fractions of the first material and the second material is 100%.

[0010] In some embodiments, the mass fraction of the first material is from 0% to 100%; the mass fraction of the second material is from 0% to 100%.

[0011] In some embodiments, the first material and the second material are in a blended state.

[0012] In some embodiments, during melt extrusion, the first material and the second material maintain their radial gradient distribution to ensure chemical compatibility and rheological stability.

[0013] In some embodiments, the first material comprises a first polymer-based composite material; the second material comprises a second polymer-based composite material, wherein the first polymer-based composite material comprises a first matrix material and a first filler material, and the second polymer-based composite material comprises a second matrix material and a second filler material, wherein the first matrix material and the second matrix material are the same or different, the first filler material and the second filler material are the same or different, and the volume fraction of the first filler material is different from the volume fraction of the second filler material.

[0014] In some embodiments, the volume fraction of the first filler material is 1-99%; the volume fraction of the second filler material is 0-20%.

[0015] In some embodiments, the first matrix material comprises a polyolefin or a polyolefin copolymer; the second matrix material comprises a polyolefin or a polyolefin copolymer.

[0016] In some embodiments, the polyolefin or polyolefin copolymer is formed by polymerization or copolymerization of one or more olefins, wherein the one or more olefins include at least one of ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, and cycloolefins.

[0017] In some embodiments, the polyolefin includes thermoplastic polyolefins or polyolefin elastomers.

[0018] In some embodiments, the thermoplastic polyolefin includes at least one of polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), and polybutene-1 (PB-1); the polyolefin elastomer includes at least one of polyisobutylene (PIB), ethylene propylene rubber (EPR), and ethylene propylene diene monomer (EPDM) rubber.

[0019] In some embodiments, the first matrix material comprises polyamide or polyamide copolymer; the second matrix material comprises polyamide or polyamide copolymer.

[0020] In some embodiments, 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.

[0021] In some embodiments, the first matrix material comprises polyester or polyester copolymer; the second matrix material comprises polyester or polyester copolymer.

[0022] In some embodiments, the polyester includes at least one of polylactic acid (PLA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene terephthalate-1,4-cyclohexanediol ester (PETG), polybutylene succinate (PBS), and polyarylate.

[0023] In some embodiments, the first matrix material comprises polycarbonate or a polycarbonate copolymer; the second matrix material comprises polycarbonate or a polycarbonate copolymer.

[0024] In some embodiments, the first matrix material comprises polyoxymethylene or a polyoxymethylene copolymer; the second matrix material comprises polyoxymethylene or a polyoxymethylene copolymer.

[0025] In some embodiments, the first matrix material comprises polyphenylene ether or a polyphenylene ether copolymer; the second matrix material comprises polyphenylene ether or a polyphenylene ether copolymer.

[0026] In some embodiments, the first matrix material comprises polyphenylene sulfide or a polyphenylene sulfide copolymer; the second matrix material comprises polyphenylene sulfide or a polyphenylene sulfide copolymer.

[0027] In some embodiments, the first matrix material comprises polyetheretherketone or a polyetheretherketone copolymer; the second matrix material comprises polyetheretherketone or a polyetheretherketone copolymer.

[0028] In some embodiments, the first matrix material comprises polysulfone or a polysulfone copolymer; the second matrix material comprises polysulfone or a polysulfone copolymer.

[0029] In some embodiments, the first matrix material comprises a liquid crystal polymer or a copolymer of liquid crystal polymers; the second matrix material comprises a liquid crystal polymer or a copolymer of liquid crystal polymers.

[0030] In some embodiments, the first matrix material comprises a thermoplastic elastomer, a rubber-like soft material, or a composite material in which the thermoplastic elastomer and the rubber-like soft material are used as the matrix resin; the second matrix material comprises a thermoplastic elastomer, a rubber-like soft material, or a composite material in which the thermoplastic elastomer and the rubber-like soft material are used as the matrix resin.

[0031] In some embodiments, the thermoplastic elastomer comprises one or more of the following: thermoplastic polyurethane elastomer (TPU), styrene-based block copolymer thermoplastic elastomer (SBS), polyolefin-based thermoplastic elastomer (POE), polyamide-based elastomer (TPAE), polyester-based elastomer (TPEE), or composite materials in which the polymer material is a matrix resin.

[0032] In some embodiments, the rubber-based soft material comprises one or more of the following: natural rubber and synthetic rubber composed of two or more of the following: styrene-butadiene rubber, ethylene-propylene rubber, nitrile rubber, silicone rubber, and fluororubber; or a composite material in which the polymer material is a matrix resin.

[0033] In some embodiments, the first filler material and the second filler material each comprise at least one of the following: calcium carbonate, magnesium carbonate, barium carbonate, barium sulfate, calcium sulfate, titanium dioxide, zinc oxide, aluminum oxide, magnesium oxide, antimony trioxide, copper powder, aluminum powder, aluminum hydroxide, magnesium hydroxide, talc, silicon dioxide, montmorillonite, diatomaceous earth, calcium silicate, mica powder, carbon black, carbon nanotubes, graphene, glass fiber, carbon fiber, basalt fiber, boron fiber, silicon carbide fiber, asbestos fiber, mineral wool fiber, whiskers, brominated flame retardant, phosphorus-nitrogen flame retardant, nitrogen-based flame retardant, starch particles, wood flour, nutshell powder, plant fiber, cellulose fiber, aramid fiber, polyester fiber, and polyamide fiber.

[0034] In some embodiments, the first material includes a first polymer material; the second material includes a second polymer material, wherein at least one property parameter of the first polymer material is different from that of the second polymer material.

[0035] In some embodiments, the at least one property parameter includes at least one of glass transition temperature and elastic tensile modulus.

[0036] In a second aspect, embodiments of this application provide a method for preparing 3D printing filament, the method comprising: determining a first material and a second material comprising the 3D printing filament; determining the mass fraction of the first material to form a gradient distribution of the first material along a radial direction, wherein the mass fraction of the first material is from 0% to 100%, and the mass fraction of the second material is from 0% to 100%; determining a blend of the first material and the second material based on the gradient distribution of the first material, wherein the sum of the mass fractions of the first material and the second material is 100%, wherein when the mass fraction of the first material is 0%, the blend does not contain the first material, and when the mass fraction of the first material is 100%, the blend does not contain the second material; preparing the blends separately; determining the number of melt extrusion devices; and adding the blends to the corresponding melt extrusion devices, extruding the melt of the blend through the same die by meteringly controlling the extrusion flow rate, and forming the 3D printing filament by cooling and traction.

[0037] In a third aspect, embodiments of this application provide the use of a 3D printing filament in the field of extrusion 3D printing, the 3D printing filament comprising the 3D printing filament according to the first aspect, or the 3D printing filament prepared according to the second aspect.

[0038] This application utilizes a radial gradient distribution in its chemical composition, which, compared to simple blends, solves the challenge of balancing printability and functionality. The specific effects vary depending on the material system. This radial gradient distribution resolves interfacial incompatibility issues, preventing interfacial defects in filaments and printed parts. During melt extrusion, laminar flow maintains this radial gradient structure, which helps improve the rheological stability between adjacent interfaces. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this specification, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 is a schematic diagram of the radial gradient distribution of the 3-printed wires according to an embodiment of this application;

[0041] Figure 2 is a flowchart of a 3D printing material preparation method according to an embodiment of this application; and

[0042] Figure 3 is a schematic diagram of an extrusion apparatus for 3D printing filament according to an embodiment of this application. Detailed Implementation

[0043] The following description provides specific application scenarios and requirements for this specification, intended to enable those skilled in the art to make and use the contents of this specification. Various partial modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of this specification. Therefore, this specification is not limited to the embodiments shown, but rather to the widest scope consistent with the claims.

[0044] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not restrictive. For example, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” used herein may also include the plural forms. When used in this specification, the terms “comprising,” “including,” and / or “containing” mean that the associated integers, steps, operations, elements, and / or components are present, but do not preclude the presence of one or more other features, integers, steps, operations, elements, components, and / or groups, or that other features, integers, steps, operations, elements, components, and / or groups may be added to the system / method.

[0045] In this application, "X includes at least one of A, B, or C" means that X includes at least A, or X includes at least B, or X includes at least C. That is, X can include any combination of A, B, and C, or any combination of A, B, and C, as well as other possible content / elements. The arbitrary combination of A, B, and C can be A, B, C, AB, AC, BC, or ABC.

[0046] In this application, unless explicitly stated otherwise, the relationships between structures can be direct or indirect. For example, when describing "A is connected to B," unless it is explicitly stated that A and B are directly connected, it should be understood that A can be directly connected to B or indirectly connected to B. Similarly, when describing "A is above B," unless it is explicitly stated that A is directly above B (AB is adjacent and A is above B), it should be understood that A can be directly above B or indirectly above B (AB is separated by other elements, and A is above B). And so on.

[0047] Considering the following description, these and other features of this specification, as well as the operation and function of related structural elements, and the economy of assembly and manufacture of components, can be significantly improved. This description also includes all figures and text in the accompanying drawings, all of which form part of this specification. However, it should be clearly understood that the drawings are for illustrative and descriptive purposes only and are not intended to limit the scope of this specification. It should also be understood that the drawings are not drawn to scale.

[0048] This application relates to an extruded 3D printing filament, its preparation method, and its applications. The chemical composition of this filament exhibits a gradient distribution in the radial direction, meaning that the chemical composition gradually changes from the center outwards. This radial gradient distribution design aims to address some problems existing in current 3D printing processes, such as weak interlayer adhesion and brittleness.

[0049] This gradient distribution, by improving interlayer bond strength, enhances and homogenizes the bond, thereby increasing the overall strength of the 3D printed part. Simultaneously, this gradient distribution also imparts higher toughness to the 3D printed part, reducing the risk of brittle fracture. Introducing a radial gradient distribution into the chemical composition addresses the issues of weak and brittle interlayer bonds in 3D printing. This improves the strength and stability of printed products, leading to better performance and application prospects for 3D printing technology. This novel 3D printing filament has potential applications in manufacturing 3D printed parts with higher strength and toughness. For example, it can be used to manufacture components in aerospace, medical, and industrial fields.

[0050] The chemical composition of the extruded 3D printing filament designed according to this application is distributed radially in a gradient pattern to improve its performance, particularly addressing issues such as weak interlayer adhesion and brittleness. The gradient distribution can positively impact the performance of the extruded 3D printing filament. For example, material adaptability optimization: Through gradient distribution, the chemical composition of the 3D printing filament can be adjusted to give it different properties in different parts. This allows for precise control of material properties, enabling it to better adapt to changes during the 3D printing process. Strength and toughness balance: In extruded 3D printing, weak interlayer adhesion and brittleness are often related to the balance between the material's strength and toughness. Gradient distribution allows for adjusting the ratio of strength to toughness in different parts of the filament, improving overall performance and reducing interlayer adhesion problems. Temperature and cooling control: During 3D printing, the temperature distribution of the material has a significant impact on the performance of the finished product. Introducing a gradient distribution into the filament allows for better control of the temperature distribution during printing, thereby improving interlayer adhesion, reducing brittleness, and improving overall quality. Rheological property optimization: During 3D printing, the extruder heats and extrudes the material; its rheological properties are crucial to print quality. By using gradient distribution, the rheological properties of the material can be adjusted, allowing it to flow more uniformly during extrusion and helping to reduce interlayer adhesion problems.

[0051] Gradient distribution, by adjusting parameters such as chemical composition, physical properties, and rheological characteristics, provides more flexibility and optimization possibilities for extrusion 3D printing filaments, thereby improving their performance during the printing process.

[0052] Specifically, the extruded 3D printing filament according to this application may have a unique gradient distribution structural feature. The structural design and characteristics of the 3D printing filament of this application are described below through specific embodiments. However, the specific embodiments are merely examples provided to facilitate understanding of the present invention, and do not represent all embodiments of this application, nor do they constitute any limitation on the scope of this application.

[0053] The extrusion 3D printing filament used for fused deposition modeling is mainly composed of a primary material and a secondary material. However, unlike traditional isotropic materials, the chemical composition of the filament exhibits a gradient variation along its radial circumference. The figure below shows the cross-section of the filament. The chemical composition of the filament is distributed radially, totaling n... s Layers. The center layer of the wire is layer 1, and along the radial direction towards the surface of the wire, the layers are layer 2, layer 3, ..., layer n, up to layer n. s Layers. In this application, the first material can also be referred to as material A, and the second material can be referred to as material B.

[0054] As shown in Figure 1, r n The radial distance from the center of the wire is represented by y. nThis indicates the nth layer of the wire, i.e., the radial distance is between r. n and r n-1 The chemical composition between them, y n =A×wt(n)+B×(1-wt(n)), meaning the chemical composition of the nth layer is related to the value of n. Material A is used as the central layer, and the mass fraction of material A, wt(1) = 100%, decreases as n gradually increases. The value of n can range from 1 to n. s Furthermore, material B serves as the outer skin layer, and the mass fraction wt(n) of material B gradually decreases as n increases, until it reaches the outer skin layer. s ) = 0%.

[0055] The value of n can be any natural number between 2 and 100. The center of the wire is defined as the first layer, and n gradually increases from the center to the surface layer.

[0056] Material A serves as the core layer, i.e., layer 1, with a mass fraction of 100%. Material B serves as the skin layer, with a mass fraction of 100%. The mass fraction of material A in the AB blend ranges from 1% to 99%, or any range between 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 99%. The mass fraction of material B also ranges from 1% to 99%, or any range between 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 99%.

[0057] The mass fraction of material A decreases as n gradually increases, meaning the mass fraction of material A in layer n is less than that in layer (n-1). Conversely, the mass fraction of material B increases as n gradually increases, meaning the mass fraction of material B in layer n is greater than that in layer (n-1).

[0058] Through the aforementioned radial gradient distribution design, the resulting filament exhibits a radial gradient distribution in its chemical composition. Compared to simple AB blends, this solves the challenge of balancing printability and functionality. Specific effects vary depending on the material system. The radial gradient distribution in chemical composition resolves the interfacial incompatibility between materials A and B, preventing interfacial defects in the filament and printed parts. Simultaneously, during melt extrusion, laminar flow maintains the radial gradient distribution structure, which helps improve chemical compatibility and rheological stability between adjacent interfaces.

[0059] According to this application, the prepared 3D printing filament exhibits a radial gradient distribution in its chemical composition. Compared to simple AB blends, this design effectively solves the problem of simultaneously achieving printability and functionality in 3D printing, although the specific effects will vary depending on the specific material system.

[0060] First, by introducing a radial gradient distribution in the chemical composition, the interfacial incompatibility between different materials (A and B) can be addressed. This helps avoid defects in the filament and the final printed part caused by poor material interfaces. This is because the interfaces between different materials are prone to weaknesses during 3D printing, which may lead to weak interlayer bonding or structural problems in the printed part.

[0061] Secondly, during melt extrusion, the designed radial gradient distribution structure helps maintain the radial gradient distribution of chemical composition through laminar flow (an ordered state of fluid flow). Laminar flow refers to the stratified and ordered state of a liquid or gas during flow. In laminar flow, the fluid flows in parallel and ordered layers, fluid particles are arranged in an ordered manner in a certain direction, and the velocity distribution of the fluid is stable and predictable. In 3D printing, the concept of laminar flow is usually associated with the material extrusion process. In extrusion 3D printing, molten material (usually plastic) is deposited layer by layer through an extruder to form the final three-dimensional structure. In laminar flow, the extruded material flows through the extruder in a uniform and ordered manner, ensuring that the material distribution of each layer is uniform and that there is no shearing or disorder.

[0062] Compared to 3D printing materials without radial gradient distribution, 3D printing materials prepared using the radial gradient distribution structure of this application have several significant advantages. For example, the design of the radial gradient distribution structure can improve the chemical compatibility between adjacent interfaces. The radial gradient distribution structure can be designed to gradually change its composition in space. This means that the material composition transitions gradually at the microscopic level, rather than changing abruptly. This gradual change in composition helps reduce chemical differences between different layers, thereby reducing chemical incompatibility at the interface. This structure can reduce interfacial tension; the higher the interfacial tension between adjacent interfaces, the stronger the interaction between materials and the worse the compatibility. The radial gradient distribution structure can reduce the interfacial tension between adjacent interfaces by changing the composition and structure of the material in different regions, thereby improving the material's compatibility. The gradient distribution structure can also reduce stress concentration; stress concentration at adjacent interfaces can lead to a decline in material performance. The radial gradient distribution structure can reduce stress concentration at adjacent interfaces by changing the composition and structure of the material in different regions, thereby improving the material's performance. Furthermore, it can reduce molecular arrangement irregularities; the radial gradient distribution structure can help reduce the irregularity of molecular arrangement at the interface. This irregularity can destabilize intermolecular interactions, increasing chemical compatibility issues. By designing a radial gradient distribution, the arrangement of molecules at the interface can be better controlled, reducing irregularity. Radial gradient distribution structures also improve the uniformity of the interface and optimize its energy distribution. A uniform interface helps form more stable chemical bonds, reducing the possibility of delamination or interface separation. This is crucial for ensuring the consistency and stability of the entire 3D printed component. The design of a radial gradient distribution structure can also optimize the energy of the interface, making it closer to the energy of adjacent structures. This helps reduce the likelihood of unstable reactions or repulsion of foreign substances at the interface, thus improving chemical compatibility. In summary, radial gradient distribution structures improve the chemical compatibility between adjacent interfaces at the microscopic level by introducing a gradient within the material. This helps improve the consistency and stability of 3D printed materials and reduces problems caused by chemical incompatibility.

[0063] Furthermore, the radial gradient distribution structure can improve the rheological stability between adjacent structures, i.e., maintain more stable flow between adjacent structures in the 3D printing filament. This has a positive impact on ensuring uniform material extrusion during printing, as well as the interlayer bonding and overall performance of the final printed part. Specifically, laminar flow allows the radial gradient distribution structure of this application to be maintained and improves the rheological stability between adjacent interfaces. Compared to 3D printing materials without radial gradient distribution, the radial gradient distribution structure can improve the rheological stability between adjacent interfaces, which may be mainly due to the following factors. The radial gradient distribution structure design allows for gradual changes in the rheological properties of the material in space. This means that the rheological properties of the material change gradually, rather than abruptly. This gradual change helps reduce differences in rheological stress, thereby improving overall rheological stability. The radial gradient distribution structure design may also improve the interfacial coupling effect between adjacent structures. This can reduce stress concentration and instability caused by differences in rheological properties. Therefore, the design of the radial gradient distribution structure helps optimize the rheological properties of 3D printing materials and improve the rheological stability of adjacent interfaces. This is crucial for ensuring the accuracy, stability, and quality of the entire 3D printing process.

[0064] Therefore, this design optimizes the chemical composition of 3D printing filaments, resolves interfacial issues between materials, and maintains a good laminar flow structure during extrusion, thereby improving the quality and performance of printed parts. This provides an innovative solution to overcome the challenges faced by traditional AB blends in 3D printing, enabling higher levels of printing accuracy and functional printing.

[0065] The following are some specific design examples based on the embodiments of this application, which do not constitute any limitation on this application.

[0066] The following detailed description is provided with reference to specific embodiments. Unless otherwise specified, the embodiments do not include components other than unavoidable impurities. Unless otherwise specified, the reagents and instruments used in the embodiments are conventionally selected in the art. Experimental methods not specifying specific conditions in the embodiments are implemented under conventional conditions, such as those described in literature, books, or methods recommended by the manufacturer.

[0067] The radial gradient distribution described above can be applied to any raw material / material for at least one 3D printing filament. For example, it can be two or more different materials with their own radial gradient distributions; it can be two or more similar materials (including materials that are similar but have different physical or chemical properties, or different components of the materials, or different contents of a certain component of the materials, and any other suitable cases).

[0068] In some embodiments, materials A and B are polymer-based composite materials. Material A includes a first polymer-based composite material, and material B includes a second polymer-based composite material. The first polymer-based composite material includes a first matrix material and a first filler material, and the second polymer-based composite material includes a second matrix material and a second filler material. The first matrix material and the second matrix material may be the same or different, and the first filler material and the second filler material may be the same or different, and the volume fraction of the first filler material is different from the volume fraction of the second filler material.

[0069] In some embodiments, materials A and B are polymer-based blends. Material A comprises a first polymer-based blend, and material B comprises a second polymer-based blend. The first polymer-based blend comprises a first matrix material and a first additive, and the second polymer-based blend comprises a second matrix material and a second additive. The first matrix material and the second matrix material may be the same or different, and the first additive and the second additive may be the same or different, and the volume fraction of the first additive is different from the volume fraction of the second additive.

[0070] The first matrix material and the second matrix material comprise polyolefins or polyolefin copolymers, wherein the polyolefins are polymeric 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 like ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene, as well as certain cyclic olefins. The polyolefins include thermoplastic polyolefins or polyolefin elastomers. Common thermoplastic polyolefins include polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polybutene-1 (PB-1), etc. Polyolefin elastomers (POEs) include polyisobutylene (PIB), ethylene propylene diene monomer (EPR), ethylene propylene diene monomer (EPDM), etc. In this application, polyolefin materials refer to materials based on polymers obtained by polymerization or copolymerization of one or more olefins.

[0071] The first matrix material and the second matrix material comprise polyamide or copolymers of polyamide: the polyamide (PA) is a polymer formed by polymerizing monomers containing carboxyl and amino groups through amide bonds. In some embodiments, the polyamide is commonly referred to as nylon, which typically refers to a condensation polymer whose constituent units can be linked by amides. For example, in this application, the nylon may be selected from one or more 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. Nylon 6 elastomer is a block copolymer, with nylon 6 as the hard segment and polyether or polyester as the soft segment. Nylon 11 elastomer is a block copolymer, with nylon 11 as the hard segment and polyether or polyester as the soft segment. Nylon 12 elastomer is a block copolymer, with nylon 12 as the hard segment and polyether or polyester as the soft segment.

[0072] The first matrix material and the second matrix material comprise polyester or copolymers of polyester. Polyester is a general term for polymers obtained by polycondensation of polyols and polyacids. It mainly refers to polyethylene terephthalate (PET), but also conventionally includes linear thermoplastic resins such as polybutylene terephthalate (PBT) and polyarylates.

[0073] The first matrix material and the second matrix material comprise polycarbonate or a copolymer of polycarbonate. Further, the polycarbonate (PC), also known as PC plastic, is a high molecular weight polymer containing carbonate groups in its molecular chain. Based on the structure of the ester groups, it can be classified into various types such as aliphatic, aromatic, and aliphatic-aromatic. The matrix materials of materials A and B comprise polyoxymethylene (POM) or a copolymer of polyoxymethylene. POM, also known as acetal resin, polyoxymethylene, or polyacetal, is a thermoplastic crystalline polymer. The matrix materials of materials A and B comprise polyphenylene ether (PPE) or a copolymer of polyphenylene ether. PPE is a high-temperature thermoplastic plastic, also known as polyphenylene oxide (PPO), which is a non-crystalline thermoplastic polymer.

[0074] The first matrix material and the second matrix material comprise polyphenylene sulfide or a copolymer of polyphenylene sulfide. Further, the polyphenylene sulfide (PPS) is a polymer containing repeating p-phenylene sulfide structural units in its molecule.

[0075] The first matrix material and the second matrix material comprise polyetheretherketone or copolymers of polyetheretherketone. Further, the polyetheretherketone (PEEK) is a linear aromatic polymer compound, with the constituent unit being oxygen-p-phenylene-carbonyl-p-phenylene, and is a semi-crystalline thermoplastic.

[0076] The first matrix material and the second matrix material comprise polysulfone or copolymers of polysulfone. Further, polysulfone (PSF or PSU) is a thermoplastic polymer whose molecular backbone contains sulfone groups (-SO2-) and aryl groups. Polysulfone possesses excellent heat resistance, chemical resistance, aging resistance, self-extinguishing properties, transparency, and high strength. In this application, polysulfone or copolymers of polysulfone may include polysulfone (PSF), polyethersulfone (PES), and polyarylsulfone (PAS), etc. Among them, polysulfone (PSF) possesses excellent heat resistance, chemical resistance, aging resistance, self-extinguishing properties, transparency, and high strength. Polyethersulfone (PES) possesses excellent heat resistance, chemical resistance, aging resistance, self-extinguishing properties, high strength, and high toughness. Polyarylsulfone (PAS) possesses excellent heat resistance, chemical resistance, aging resistance, self-extinguishing properties, high strength, and high stiffness.

[0077] The first matrix material and the second matrix material may further comprise liquid crystal polymer materials or copolymers of liquid crystal polymer materials. The liquid crystal polymer, also called a liquid crystal polymer (LCP), is a novel type of polymer material that generally transforms into a liquid crystal form under certain heating conditions.

[0078] Furthermore, the first and second filler materials mentioned above can also include many different materials and different combinations thereof. For example, filler materials include one or more inorganic substances selected from carbonates (calcium carbonate, magnesium carbonate, barium carbonate, etc.), sulfates (barium sulfate, calcium sulfate, etc.), metal oxides (titanium dioxide, zinc oxide, aluminum oxide, magnesium oxide, antimony trioxide, etc.), metal powders (copper powder, aluminum powder, etc.), metal hydroxides (aluminum hydroxide, magnesium hydroxide, etc.), silicon-containing compounds (talc, silicon dioxide, montmorillonite, diatomaceous earth, calcium silicate, mica powder, etc.), and carbon-based materials (carbon black, carbon nanotubes, graphene).

[0079] The first filler material and the second filler material may further include one or more inorganic fiber materials selected from glass fiber, carbon fiber, basalt fiber, boron fiber, silicon carbide fiber, asbestos fiber, mineral wool fiber, and whiskers.

[0080] The first filler material and the second filler material may also include one or more mixed organic compounds selected from organic flame retardants (bromine-based, phosphorus-nitrogen-based, nitrogen-based, etc.), starch particles, wood flour, nut shell powder, etc.

[0081] The first and second filler materials may further include one or more organic compounds selected from plant fibers, cellulose fibers, and synthetic fibers (aramid fibers, polyester fibers, polyamide fibers, etc.). The filler material forms include one or more mixtures of powder, granules, fibers, and flakes.

[0082] The first and second additives include one or more mixtures of slip agents, opening agents, antistatic agents, matting agents, plasticizers, internal and external lubricants, scratch resistant agents, abrasion resistant agents, flame retardants, anti-dripping agents, toughening agents, chain extenders, antioxidants, light stabilizers, UV resistant agents, nucleating agents, compatibilizers, etc.

[0083] In some embodiments, when the 3D printing material comprises two materials, A and B, the volume fraction of the second filler material in material B is 0-20%, for example, any range between 1%, 5%, 10%, 15%, and 20%. The volume fraction of the first filler material in material A is higher than that in material B, ranging from 1-99%, for example, any range between 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 99%.

[0084] The 3D printing filament prepared in this way has stronger bonding strength between different layers during printing. The interlayer bonding strength of this 3D printing filament is significantly better than that of material A or AB blend material used alone. This solves the problem of decreased interlayer bonding strength of composite filler filaments in the prior art, as well as the problem of significant weakening of interlayer bonding under high filler content conditions.

[0085] For example, in the examples below, the embodiment is a 3D printing material with radial gradient distribution characteristics prepared according to this application, while the comparative example is a blend material of the same material without gradient distribution characteristics.

[0086] Example 1

[0087] The aforementioned filament was fed into a fused deposition modeling (FDM) 3D printer to produce printed parts that met the testing requirements. The performance of the printed parts was then tested, and the results are compared in the table below:

[0088] As can be seen, the filament of Example 1-1 exhibits good toughness and is not easily broken. This is typically an important performance characteristic in 3D printing applications, especially when parts require a certain degree of elasticity and impact resistance. In contrast, the filament of the comparative example is prone to brittle fracture and is difficult to use for printing. The lack of sufficient toughness may make it more susceptible to breakage during printing and use. Specifically, the XY tensile strength of Example 1-1 is 105.4 ± 3.2 MPa, while the data for the comparative example could not be effectively measured. The data from Example 1-1 shows a relatively high tensile strength, indicating that the material has good tensile properties in a plane. The XY tensile modulus of Example 1-1 is 7563 ± 35 MPa, while the data for the comparative example could not be effectively measured. The XY tensile modulus characterizes the elastic modulus of a material in the XY plane and is used to describe the material's deformation properties under stress. The XY tensile modulus of Example 1-1 is high. The Z tensile strength of Example 1-1 is 75.4 ± 1.2 MPa. The strength in the Z direction is generally lower than that in the XY direction, but this value still provides information about the performance in the vertical direction. The XY flexural strength of Example 1-1 is 126.3 ± 8.5 MPa, which indicates that the material also has good flexural strength in the XY plane and is suitable for applications requiring certain flexural performance.

[0089] In summary, the filament and printed parts of Examples 1-1 exhibited better performance in terms of toughness, strength, and bending properties, while the filament of Examples 1-2 showed poor toughness, with surface cracks, making stable and continuous printing impossible. The filament of the comparative example was brittle and prone to breakage, making it unsuitable for printing. Since the raw material components (glass fiber and nylon 6) used in the examples and comparative examples were completely identical, differing only in their distribution characteristics within the resulting printed materials, Examples 1-1 showed a radial gradient distribution with the filler volume fraction decreasing from the inside out, while Examples 1-2 showed a radial gradient distribution but with the filler volume fraction increasing from the inside out. The comparative example, however, was a homogeneous blend without a gradient. Therefore, the design of the radial gradient distribution in this application has a crucial impact on the properties of the resulting material.

[0090] Example 2

[0091] The aforementioned filament was fed into a fused deposition modeling (FDM) 3D printer to produce printed parts that met the testing requirements. The performance of the printed parts was then tested, and the results are compared in the table below:

[0092] The incorporation of the flame retardant ammonium polyphosphate (APP) into nylon 6 significantly affects the melt deposition process of nylon 6, resulting in a significant weakening of the Z-axis interlayer strength of the printed nylon 6 parts. However, the composite structure described in Example 2-1 achieves overall flame retardancy of the printed part while ensuring that the Z-axis interlayer strength does not decrease significantly. Although Example 2-2 also employs a gradient structure composite method, the high flame retardant content on the filament surface layer, which acts as the bonding layer between Z-axis layers during printing, leads to a significant decrease in Z-axis interlayer strength.

[0093] In some embodiments, A and B may be polymer materials. Material A may include a first polymer material, and material B may include a second polymer material. The first polymer material and the second polymer material are different. Further, at least one property parameter of the first polymer material differs from that of the second polymer. For example, the glass transition temperature (Tg) of the first polymer material differs from that of the second polymer. Another example is that the elastic tensile modulus of the first polymer material differs from that of the second polymer.

[0094] The glass transition temperature (Tg) is the temperature at which a glassy material can reversibly transition between its glassy and elastic states. It should be understood that 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 to measure 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. These measurement methods can include volume changes (dilatometer method), thermodynamic properties (differential thermal analysis (DTA) and differential scanning calorimetry (DSC), changes in mechanical properties (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. Therefore, the description of Tg values ​​in this application is a comparison of Tg values ​​under the same testing methods and conditions.

[0095] Therefore, Tg refers to the temperature at which a glassy material undergoes a reversible transition between the glassy and elastic states; it is the temperature at which molecular chain segments begin to move during the heating process of a polymer material. Descriptions of Tg values ​​should be compared under the same testing methods and conditions. Tg is one of the important characteristics of polymer materials and can be used to characterize their properties. Specifically, the glass transition temperature (Tg) is important in 3D printing materials, especially for polymer-based materials. Tg is the transition temperature from the glassy to the elastic state, affecting the material's state and mechanical properties. The value of Tg is related to the movement of polymer molecular chains. In 3D printing, if the temperature exceeds Tg, the molecular chains may become sufficiently active, causing the material to lose its shape during printing and affecting molding accuracy. Tg has a direct impact on the mechanical properties of the material. Below Tg, the material typically exhibits the hardness and brittleness of the glassy state, while above Tg it exhibits the characteristics of the elastic state. Generally, the higher the Tg, the better the heat resistance of the material. Therefore, materials with high Tg are more suitable for use in high-temperature environments; while the lower the Tg, the better the material's flowability.

[0096] In the following embodiments, materials with different Tg values ​​are designed to have a radial gradient distribution. Material A is a high Tg material, and material B is a low Tg material. The glass transition temperature (Tg) ranges for materials A and B are -80℃ to 380℃, for example, -60℃, -40℃, -20℃, 0℃, 20℃, 40℃, 60℃, 80℃, 100℃, 120℃, 140℃, 160℃, 180℃, 200℃, 220℃, 240℃, 260℃, 280℃, 300℃, 320℃, 340℃, 360℃, 380℃, etc., or any range thereof. The Tg difference between materials A and B can be 1-300℃, for example, 1℃, 20℃, 40℃, 60℃, 80℃, 100℃, 120℃, 140℃, 160℃, 180℃, 200℃, 220℃, 240℃, 260℃, 280℃, 300℃, etc., or any range therein.

[0097] Example 3

[0098] The aforementioned filament was fed into a fused deposition modeling (FDM) 3D printer to produce printed parts that met the testing requirements. The performance of the printed parts was then tested, and the results are compared in the table below:

[0099] The examples and comparative examples use the same raw materials, but the examples have a radial gradient distribution, while the comparative examples are simple blends. As can be seen from the test results above, the XY tensile strength of the examples is significantly higher than that of the comparative examples. This is likely due to the radial gradient distribution resulting in a more uniform and optimized material structure, improving the overall strength of the material. Fracture typically occurs in weak areas of the material. A radial gradient distribution can make the material's strength more uniform, thereby improving its tensile strength. Similar to the XY tensile strength, the tensile strength of the examples in the Z direction is also significantly higher than that of the comparative examples, indicating that the gradient distribution may have a positive effect in all directions. The examples also exhibit higher flexural strength in the XY directions, suggesting that the gradient distribution may have a positive impact on the material's performance under flexural stress. Flexural stress in materials is typically concentrated in the flexural region. A radial gradient distribution can make the flexural stress distribution more uniform, thereby improving the material's flexural strength. The significant increase in notched impact strength may indicate that the examples have better impact resistance, which may be a key performance indicator in some applications. Fracture typically occurs at the notch. A radial gradient distribution can improve the notch toughness of the material, thereby increasing its notched impact strength.

[0100] Therefore, the embodiments significantly outperform the comparative examples in all performance metrics. This indicates that a radial gradient distribution can improve the mechanical properties of materials, including strength, toughness, and impact resistance. This may have practical application potential for materials requiring different properties in specific applications. The performance of the embodiments is significantly improved, which is attributed to their radial gradient distribution.

[0101] Example 4

[0102] The aforementioned filament was fed into a fused deposition modeling (FDM) 3D printer to produce printed parts that met the testing requirements. The performance of the printed parts was then tested, and the results are compared in the table below:

[0103] Since the heat resistance (Tg) of PETG is significantly higher than that of PLA, the main objective of PETG-PLA composites is to improve the heat resistance of PLA materials. However, in the simple blend system (comparative example), the Z-axis interlaminar strength of the material is significantly reduced, and the Vicat softening temperature is also significantly lower than that of the example.

[0104] In some embodiments, the tensile modulus of the first polymer material differs from that of the second polymer, meaning that the tensile modulus of material A differs from that of material B. The tensile modulus of elasticity is an important method and performance parameter characterizing the rigidity of polymer materials. It is measured through tensile tests on standard specimens. The specimen size and test conditions will affect the test results to some extent. Therefore, the relative magnitudes of the tensile modulus values ​​of the polymer materials are compared using the same test method standard, specimen size, and test conditions (tensile rate). The test method refers to standards GB / T 1040-2018 and ISO 527:2012, using a tensile test speed of 1 mm / min.

[0105] 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) under elastic deformation. In some cases, the tensile modulus can be used 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 the material. The tensile modulus, also known as the tensile elastic modulus, 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.

[0106] Tensile modulus is an important physical property describing a material's resistance to deformation during stretching. For filaments or materials used in 3D printing, tensile modulus is one of the key indicators for measuring a material's stiffness and elasticity. In 3D printing, parts made using filaments may require a certain level of stiffness and elasticity to ensure they do not deform excessively or lose their shape during use. The higher the tensile modulus, the less likely the material is to undergo tensile deformation under stress, thus improving the mechanical properties of the part. During the 3D printing process, the material's transformation from a filament state to the final part involves multiple factors, including temperature changes and structural stacking. The tensile modulus of a material affects its deformation behavior during printing; materials with high tensile modulus are more likely to maintain their shape, contributing to improved printing accuracy. On the other hand, materials with low tensile modulus have higher ductility, thus offering several advantages in 3D printing. Low tensile modulus materials deform more easily during printing, allowing for the printing of more complex shapes, such as those with internal spaces or thin walls. Low tensile modulus materials are less likely to break under tension, thus reducing the likelihood of printing failures. Simultaneously, low tensile modulus materials are more likely to maintain their shape, allowing for higher printing accuracy. Therefore, in some applications, 3D wires composed of two or more materials with different tensile moduli distributed along a radial gradient have a more balanced tensile modulus and related mechanical properties at various points, and can combine the advantages of different materials.

[0107] In the following embodiments, materials with different tensile moduli are designed to have a radial gradient distribution. The elastic tensile moduli of materials A and B range from 1 MPa to 10 GPa, for example, 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, etc., or any range therebetween. The difference in elastic moduli between materials A and B can range from 1 MPa to 5 GPa, for example, 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, etc., or any range therebetween.

[0108] In some embodiments, the tensile modulus of elasticity of material A is greater than that of material B. The results show that the prepared filament exhibits high interlaminar toughness, achieving a balanced stiffness and toughness material with high overall stiffness and excellent interlaminar toughness. This design choice may aim to achieve a balance between stiffness and toughness, i.e., increasing the material's toughness while maintaining a certain level of stiffness. A material with a balanced stiffness and toughness possesses both sufficient stiffness (high elastic modulus) and good toughness (able to absorb a certain degree of deformation and energy without easily breaking). By selecting material A, which has a higher tensile modulus of elasticity, the designer may aim to enhance the overall structural rigidity while providing better toughness through material B. Good interfacial adhesion and compatibility are observed between each layer in the 3D printing. Improved interlaminar toughness helps prevent interlaminar delamination or crack formation, thereby improving the overall strength and durability of the part. The stiffness of material A provides the material's strength and rigidity, while the toughness of material B provides the material's impact resistance and fracture toughness. Therefore, the prepared filament with gradient distribution characteristics exhibits a balanced stiffness and toughness with high overall stiffness and excellent interlaminar toughness. The high tensile modulus of elasticity of material A contributes to the overall structural rigidity, making the fabricated wire less prone to deformation under stress. The improved interlaminar toughness not only enhances the material's properties in the horizontal direction but also helps resist stress and deformation in the vertical direction. In summary, by selecting material A, which has a high tensile modulus of elasticity, while maintaining the interlaminar toughness of material B, an overall balance between rigidity and toughness is achieved.

[0109] Example 5

[0110] The aforementioned filament was fed into a fused deposition modeling (FDM) 3D printer to produce printed parts that met the testing requirements. The performance of the printed parts was then tested, and the results are compared in the table below:

[0111] The embodiment exhibits higher tensile strength in the XY direction, indicating that the gradient-distributed material performs better in this direction. The embodiment also performs better in the Z direction, exhibiting higher tensile strength. Similarly, the embodiment performs better in the XY direction, exhibiting higher flexural strength. The embodiment shows significantly better notched impact strength, which may indicate that the gradient-distributed material has better resistance to impact and fracture. Overall, the gradient-distributed material of the embodiment outperforms the comparative example in tensile strength, flexural strength, and notched impact strength in both the XY and Z directions. This demonstrates that gradient-distribution design can optimize material properties in different directions, improving overall performance, especially in multi-directional stress or complex applications.

[0112] In some embodiments, the tensile modulus of material A is less than that of material B. Results show that the prepared gradient-distributed filament improves the overall rigidity of the soft filament, enhances the extrusion transportability of the soft elastomer material during printing, and solves the problem of filament slippage, thereby improving the smoothness of filament transport in the print head and thus increasing printing efficiency. Gradient distribution improves overall rigidity. Since the tensile modulus of material A is less than that of material B, the gradient-distributed filament exhibits a gradually increasing modulus of elasticity from the core to the surface radially. This design helps improve the overall rigidity of the soft filament, resulting in better performance of printed parts in areas requiring a certain level of rigidity. Soft elastomer materials often face challenges such as flowability and deformability during extrusion transport. The gradually increasing modulus of elasticity in the filament, achieved through gradient distribution design, helps improve the extrusion transportability of soft materials. This means that during printing, the soft material is more easily extruded uniformly, contributing to the formation of stable and refined printed structures. Filament slippage refers to the insufficient resistance encountered by the print head during filament transport during 3D printing to ensure a continuous filament supply, leading to printing interruptions or quality degradation. This problem can be addressed by using a gradient distribution of different tensile moduli. By improving the overall rigidity of the soft filament, extrusion delivery performance, and resolving filament slippage, this gradient design helps improve 3D printing efficiency. Smoother filament delivery ensures stable printhead operation, thereby improving the reliability and efficiency of the printing process. In summary, this design, by using a gradient-distributed filament and introducing gradually increasing elastic moduli into the material, solves a series of challenges associated with soft filaments in the printing process, thus improving printing efficiency and manufacturing quality.

[0113] Example 6

[0114] The aforementioned filament was fed into a fused deposition modeling (FDM) 3D printer to produce printed parts that met the testing requirements. The performance of the printed parts was then tested, and the results are compared in the table below:

[0115] In some embodiments, the radial gradient distribution of the first and second materials is continuously varied. To achieve specific functions or visual effects, different types of additives are introduced into 3D printing materials. These additives are generally classified into two main categories: organic and inorganic. Organic molecular additives are widely used. However, when organic additives, especially small organic molecule additives, are used in 3D printing materials, they can affect the molecular chain diffusion and entanglement process during 3D printing deposition, adversely affecting the interlayer adhesion properties of the 3D printing material.

[0116] On the other hand, organic additives migrate from the interior of the material to the surface during actual processing or application, affecting the material's properties. For example, organic matting agents tend to migrate to the surface during plastic processing and molding due to differences in surface tension, thus achieving a matte finish. Organic slip agents gradually migrate from between polymer molecular chains to the surface during processing, molding, and long-term use, achieving a slippery effect. The migration of organic antistatic agents can form a charge-rich film on the plastic surface, thus achieving an antistatic effect. However, if all of them migrate to the surface, the antistatic effect of the material will gradually disappear, making it difficult to achieve long-lasting antistatic properties.

[0117] In general, the migration behavior of organic additives in the processing or use of thermoplastic polymer materials is prevalent, producing both positive and negative effects. Therefore, when using these organic additives in 3D printing materials, controlling their distribution and migration rate within the thermoplastic substrate is crucial. It is essential to ensure that additive migration does not affect interlayer adhesion during printing, while simultaneously expecting the additives to migrate to the surface at a specific rate during processing and application to exert their intended effects. Therefore, for 3D printing filaments, the design of a gradient distribution of organic additives in the radial direction of the filament is particularly important.

[0118] Example 7

[0119] The aforementioned filament was fed into a fused deposition modeling (FDM) 3D printer to produce printed parts that met testing requirements. The performance of the printed parts was then tested, and the results are compared in the table below:

[0120] The fused deposition modeling process in printing relies on the diffusion and entanglement between polymer molecular chains. The addition of additives can weaken this process, ultimately affecting polymer properties, primarily manifested as a decrease in Z-axis strength, leading to increased anisotropy in the printed part. By introducing a component with a high antistatic agent content into the central layer and controlling the processing technology, the antistatic agent can be gradient-distributed within the filament. This maintains a relatively long-lasting antistatic effect while ensuring interlayer strength along the Z-axis. During long-term use of the printed part, the antistatic agent migrates to the surface at a certain rate, achieving surface antistatic effects. The advantage of gradient distribution over uniform distribution is that its migration rate is controllable, thus achieving a long-lasting antistatic effect while ensuring the material's Z-axis tensile properties.

[0121] This application further provides a method for preparing 3D printing filaments designed for gradient distribution characteristics. It should be intentionally stated that these steps do not necessarily need to be performed in the described order; for example, some steps may be performed simultaneously, while others may be performed in reverse order. This application itself is not restrictive in this regard. The method may include the following steps: determining a first material and a second material comprising the 3D printing filament; determining the mass fraction of the first material to form a radial gradient distribution of the first material, wherein the mass fraction of the first material is from 0% to 100%, and the mass fraction of the second material is from 0% to 100%; determining a blend of the first material and the second material based on the gradient distribution of the first material, wherein the sum of the mass fractions of the first material and the second material is 100%, wherein when the mass fraction of the first material is 0%, the blend does not contain the first material, and when the mass fraction of the first material is 100%, the blend does not contain the second material; preparing the blends separately; determining the number of melt extrusion devices; adding the blends to the corresponding melt extrusion devices, extruding the melt of the blends through the same die by metering the extrusion flow rate, and forming the 3D printing filament by cooling and traction.

[0122] This method may specifically include the steps described below. Figure 3 is a schematic diagram of the extrusion device for 3D printing filament, where 1: single-screw extruder one, 2: single-screw extruder two, 3: single-screw extruder three, 4: single-screw extruder four, 5: single-screw extruder five, 6: melt co-extrusion die, 11: material A, 12: AB blend material one, 13: AB blend material two, 14: AB blend material three, 15: material B, and 16: 3D printing filament. The specific steps are as follows: design the number of layers n of the 3D printing filament, and design the mass fraction gradient of material A in the AB blend in the n layers. Design AB blends containing different mass fractions of material A in the corresponding layers from the 1st to the nth layer. Prepare AB blends containing different mass fractions of material A using a twin-screw extruder. Set the number of melt extrusion devices (i.e., single-screw extruders) according to the number of layers n, with the number of extruders equal to the number of layers n of the filament. Place material A, material B, and AB blends containing different mass fractions of material A into different melt extrusion devices—single-screw extruders. Extrude the melt of the n materials through the same die by metering the extrusion flow rate. After cooling and traction, form 3D printing filaments and finally obtain radial gradient structure filaments containing n layers of material.

[0123] The gradient distribution design of materials A and B promises to achieve a balance between printability and functionality in terms of chemical composition. By using a radial gradient, the composition of the material can be controlled at different locations, thereby optimizing the performance of specific areas and improving the overall performance of the material. This allows the material to meet both the requirements of the printing process and provide the necessary functional properties. The radial gradient distribution in chemical composition also helps to solve the interfacial incompatibility problem between materials A and B. In traditional AB blends, interfacial incompatibility can lead to interfacial defects in the filament and printed parts, affecting overall performance. The radial gradient distribution structure is expected to improve the material interface, enhancing compatibility and adhesion. During melt extrusion, the radial gradient distribution structure can maintain a laminar flow structure. This structure helps improve the rheological stability between adjacent interfaces, reducing the risk of interlayer delamination or cracking. This is crucial for improving print quality and maintaining manufacturing consistency. The radial gradient distribution design in chemical composition of this application has potential advantages in solving the problem of balancing printability and functionality. This design not only helps optimize material performance but also solves the interfacial problem between materials A and B, while improving the rheological stability during melt extrusion, providing new possibilities for the development of 3D printing technology.

[0124] Therefore, this application possesses a radial gradient distribution in its chemical composition, which, compared to simple blends, solves the problem of balancing printability and functionality. Specific effects vary depending on the material system. Simultaneously, the radial gradient distribution in the chemical composition can resolve interfacial incompatibility issues, avoiding interfacial defects in filaments and printed parts. During melt extrusion, laminar flow maintains the radial gradient distribution structure, which helps improve the rheological stability between adjacent interfaces.

[0125] The foregoing has described specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0126] In summary, after reading this detailed disclosure, those skilled in the art will understand that the foregoing detailed disclosure may be presented by way of example only and may not be restrictive. Although not explicitly stated herein, those skilled in the art will understand that this specification requires various reasonable changes, improvements, and modifications to the embodiments. These changes, improvements, and modifications are intended to be made by this specification and are within the spirit and scope of the exemplary embodiments described herein.

[0127] Furthermore, certain terms in this specification have been used to describe embodiments of this specification. For example, "an embodiment," "an embodiment," and / or "some embodiments" mean that a particular feature, structure, or characteristic described in connection with that embodiment may be included in at least one embodiment of this specification. Therefore, it is to be emphasized and understood that two or more references to "an embodiment" or "an embodiment" or "alternative embodiment" in various parts of this specification do not necessarily refer to the same embodiment. Moreover, specific features, structures, or characteristics may be suitably combined in one or more embodiments of this specification.

[0128] It should be understood that in the foregoing description of the embodiments in this specification, various features are combined in a single embodiment, drawing, or description for the purpose of simplifying the description and to aid in understanding a feature. However, this does not mean that the combination of these features is necessary, and those skilled in the art may extract some features as individual embodiments when reading this specification. That is, the embodiments in this specification can also be understood as an integration of multiple sub-embodiments. It is also valid when each sub-embodiment contains fewer than all the features of a single foregoing disclosed embodiment.

[0129] Each patent, patent application, publication of the patent application, and other materials such as articles, books, specifications, publications, documents, articles, etc., cited herein may be incorporated by reference. The entire contents used for all purposes, except for any history of prosecution documents associated with it, that may be inconsistent with or conflict with this document, or that may have a limiting effect on the widest extent of the claims, are now or hereafter associated with this document. For example, in the event of any inconsistency or conflict between the description, definition, and / or use of terms associated with any of the included materials and the terms, description, definition, and / or used in connection with this document, the terms used herein shall prevail.

[0130] Finally, it should be understood that the embodiments disclosed herein are illustrative of the principles of the embodiments described in this specification. Other modified embodiments are also within the scope of this specification. Therefore, the embodiments disclosed in this specification are merely examples and not limitations. Those skilled in the art can implement the applications described in this specification using alternative configurations based on the embodiments in this specification. Therefore, the embodiments in this specification are not limited to the embodiments precisely described in the applications.

Claims

1. An extruded 3D printing thread, characterized in that , comprising: a first material; and a second material, wherein each of the first material and the second material has a gradient distribution along a radial direction.

2. The 3D printing filament of claim 1, wherein , a mass fraction of the first material gradually decreases from inside to outside along the radial direction; a mass fraction of the second material gradually increases from inside to outside along the radial direction; a sum of the mass fraction of the first material and the mass fraction of the second material is 100%.

3. The 3D printing filament of claim 2, wherein , the mass fraction of the first material is from 0% to 100%; the mass fraction of the second material is from 0% to 100%.

4. The 3D printing filament of claim 1, wherein , the first material and the second material are in a blended state.

5. The 3D printing filament of claim 1, wherein , In a melt extrusion process, the first material and the second material maintain their gradient distribution along the radial direction to ensure chemical compatibility and rheological stability.

6. The 3D printing filament of claim 1, wherein , the first material comprises a first polymeric matrix material; the second material comprises a second polymeric matrix material, wherein the first polymeric matrix material comprises a first base material and a first filler material, the second polymeric matrix material comprises a second base material and a second filler material, the first base material and the second base material are the same or different, and the first filler material and the second filler material are the same or different.

7. The 3D printing filament of claim 6, wherein , a volume fraction of the first filler material is 1-99%; a volume fraction of the second filler material is 0-20%.

8. The 3D printing filament of claim 6, wherein , the first base material comprises a polyolefin or a polyolefin copolymer; the second base material comprises a polyolefin or a polyolefin copolymer.

9. The 3D printing filament of claim 8, wherein , the polyolefin or polyolefin copolymer is formed by polymerization or copolymerization of one or more olefins, wherein the one or more olefins comprise at least one of ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, and a cyclic olefin.

10. The 3D printing filament of claim 8, wherein , the polyolefin comprises a thermoplastic polyolefin or a polyolefin elastomer.

11. The 3D printing filament of claim 10, wherein , the thermoplastic polyolefin comprises at least one of polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), and polybutene-1 (PB-1); the polyolefin elastomer comprises at least one of polyisobutylene (PIB), ethylene propylene rubber (EPR), and terpolymer ethylene propylene rubber (EPDM rubber).

12. The 3D printing filament of claim 6, wherein , the first base material comprises a polyamide or a polyamide copolymer; the second base material comprises a polyamide or a polyamide copolymer.

13. The 3D printing filament of claim 12, wherein , the polyamide comprises 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 of claim 6, wherein , the first base material comprises a polyester or a polyester copolymer; the second base material comprises a polyester or a polyester copolymer.

15. The 3D printing filament of claim 14, wherein , the polyester comprises at least one of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyarylate.

16. The 3D printing filament of claim 6, wherein , the first base material comprises a polycarbonate or a polycarbonate copolymer; the second base material comprises a polycarbonate or a polycarbonate copolymer.

17. The 3D printing filament of claim 6, wherein , the first base material comprises a polyoxymethylene or a polyoxymethylene copolymer; the second base material comprises a polyoxymethylene or a polyoxymethylene copolymer.

18. The 3D printing filament of claim 6, wherein , the first base material comprises a polyphenylene ether or a polyphenylene ether copolymer; The second matrix material comprises polyphenylene ether or polyphenylene ether copolymer.

19. The 3D printing filament of claim 6, wherein , The first matrix material comprises polyphenylene sulfide or polyphenylene sulfide copolymer. The second matrix material comprises polyphenylene sulfide or polyphenylene sulfide copolymer.

20. The 3D printing filament of claim 6, wherein , The first matrix material comprises polyether ether ketone or polyether ether ketone copolymer. The second matrix material comprises polyether ether ketone or polyether ether ketone copolymer.

21. The 3D printing filament of claim 6, wherein , The first matrix material comprises polysulfone or polysulfone copolymer. The second matrix material comprises polysulfone or polysulfone copolymer.

22. The 3D printing filament of claim 6, wherein , The first matrix material comprises liquid crystal polymer or copolymer of liquid crystal polymer. The second matrix material comprises liquid crystal polymer or copolymer of liquid crystal polymer.

23. The 3D printing filament of claim 6, wherein , The first filler material and the second filler material each comprise at least one of calcium carbonate, magnesium carbonate, barium carbonate, barium sulfate, calcium sulfate, titanium dioxide, zinc oxide, aluminum oxide, magnesium oxide, antimony trioxide, copper powder, aluminum powder, aluminum hydroxide, magnesium hydroxide, talc, silica, montmorillonite, diatomite, calcium silicate, mica powder, carbon black, carbon nanotube, graphene, glass fiber, carbon fiber, basalt fiber, boron fiber, silicon carbide fiber, stone wool fiber, mineral wool fiber, whisker, bromine-based flame retardant, phosphorus-nitrogen-based flame retardant, nitrogen-based flame retardant, starch particle, wood powder, shell powder, plant fiber, cellulose fiber, aramid fiber, polyester fiber, polyamide fiber.

24. The 3D printing filament of claim 1, wherein , The first material comprises a first polymeric material; The second material comprises a second polymeric material, wherein At least one property parameter of the first polymeric material is different from the second polymeric material.

25. The 3D printing filament of claim 24, wherein , The at least one property parameter comprises at least one of glass transition temperature and elastic tensile modulus.

26. A method of producing a 3D printing filament, characterized in that The method comprises: determining the first material and the second material comprised by the 3D printing wire; determining a mass fraction of the first material to constitute a gradient distribution of the first material along the radial direction, wherein the mass fraction of the first material is from 0% to 100%, and the mass fraction of the second material is from 0% to 100%; determining a blend of the first material and the second material according to the gradient distribution of the first material, wherein the sum of the mass fraction of the first material and the mass fraction of the second material is 100%, the blend does not contain the first material when the mass fraction of the first material is 0%, and the blend does not contain the second material when the mass fraction of the first material is 100%; preparing the blend; determining the number of the melt extrusion devices; and feeding the blend into the corresponding melt extrusion devices, extruding the melt of the blend through the same die by metering control of the extrusion flow, and forming the 3D printing wire through cooling and traction.

27. Use of a 3D printing filament in the field of extrusion-based 3D printing, characterized in that The 3D printing wire comprises the 3D printing wire according to any one of claims 1-26, or the 3D printing wire prepared according to claim 27.

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