Graphene-reinforced 3D printing material and method of making the same

Abstract

The application discloses a graphene-reinforced 3D printing material and a preparation method thereof, and comprises a multifunctional core-shell structure filler and a base material; the multifunctional core-shell structure filler comprises an inner core, a graphene intermediate layer wrapping the inner core and a reactive encapsulation shell wrapping the graphene intermediate layer; the base material comprises one of a photocuring resin slurry, a thermoplastic plastic wire and a thermoplastic plastic powder; by adjusting the base system, the same core-reinforced filler can be seamlessly adapted to three major mainstream printing processes, i.e., photocuring, fused deposition and powder bed fusion, so that one material is used for multiple purposes, and the universality and research and development efficiency of a material platform are greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of 3D printing additive manufacturing technology, specifically referring to a graphene-reinforced 3D printing material and its preparation method. Background Technology

[0002] 3D printing (additive manufacturing) technology has shown great potential in aerospace, biomedicine, and electronics due to its advantages in complex structure forming, material saving, and high design freedom. However, traditional 3D printing materials, especially resin-based or plastic-based materials, often fail to meet the demands of high-end applications in terms of mechanical properties, thermal / electrical conductivity, and multifunctional integration. Introducing high-performance nanofillers (such as graphene) is an effective way to improve matrix properties, but in practical applications, especially in the field of 3D printing with multiple process adaptability, a series of unresolved technical bottlenecks still exist. Dispersion and interface issues of nanofillers: Graphene has a large specific surface area and high surface energy, making it prone to agglomeration in polymer matrices. This not only creates stress concentration points, weakening the reinforcing effect, but also severely affects the rheological properties of printing pastes or filaments (such as excessive viscosity and nozzle clogging) and curing / crystallization behavior. Furthermore, the interfacial bonding between graphene and matrices with different properties (such as photocurable resins and thermoplastics) is weak, resulting in low stress transfer efficiency, which limits the full realization of its reinforcing and toughening effects.

[0003] Poor process adaptability and limited functionality: Existing technologies typically develop specialized composite materials for a single printing process (such as those applicable only to photopolymerization or fused deposition modeling). For example, high-solids-content nanocomposite slurries suitable for photopolymerization have formulations that are drastically different from composite filaments suitable for fused deposition modeling or composite powders suitable for powder bed fusion modeling, lacking a universal reinforcement system that can be applied across platforms. This results in high material development costs and long development cycles, and the functionality of printed parts (such as electrical and thermal conductivity) often relies on the simple physical mixing of fillers, making it difficult to achieve precise spatial distribution control and multifunctional integration.

[0004] The integration of structure and function in manufacturing is challenging: Current composite material-based 3D printing primarily focuses on the forming process itself, resulting in mostly homogeneous or simple gradient structures. For applications requiring the integration of multiple functions such as load-bearing capacity, heat dissipation pathways, conductive circuits, or electromagnetic shielding within the same component, existing technologies typically employ post-assembly or complex post-processing methods. This increases process complexity and may introduce weaknesses. There is a lack of a technological solution that can simultaneously achieve "structural creation" and "functional integration" during the printing process or through simple and efficient post-processing.

[0005] Therefore, developing a new type of composite material and its preparation method that can fundamentally solve the problems of graphene dispersion and interface, be widely compatible with mainstream 3D printing processes, and easily achieve structural-functional integration has become the key to promoting the development of high-performance additive manufacturing. Summary of the Invention

[0006] To address the needs and problems mentioned in the background above, this invention provides a graphene-reinforced 3D printing material and its preparation method, thereby at least partially solving the aforementioned problems.

[0007] According to the technical solution of the present invention, in a first aspect, the present invention provides a graphene-reinforced 3D printing material, comprising a multifunctional core-shell structure filler and a matrix material; the multifunctional core-shell structure filler comprises a core, a graphene intermediate layer encapsulating the core, and a reactive encapsulation shell encapsulating the graphene intermediate layer; the matrix material comprises one of photocurable resin slurry, thermoplastic plastic filament, and thermoplastic plastic powder.

[0008] Preferably, the core comprises one of hollow glass microspheres, hollow ceramic microspheres, and thermally decomposable polymer microspheres, and the particle size of the core is 5-50 μm; The number of layers in the graphene intermediate layer is 1-10; The reactive encapsulation shell layer is made of one or more of the following materials: silane coupling agent-grafted polymer, silicon dioxide, and aluminum oxide, and the thickness of the reactive encapsulation shell layer is 10-200 nm.

[0009] Preferably, when the printing consumable is configured to be compatible with photopolymerization 3D printing, the matrix material is a photopolymerization resin slurry, and the photopolymerization resin slurry comprises the following materials by mass percentage: The light diffuser comprises 90-95% photosensitive resin, 1-5% multifunctional core-shell structure filler, and 0.1-0.5% light diffusion modifier; the light diffusion modifier includes surface-modified nanodiamond or zirconium oxide nanoparticles.

[0010] Preferably, when the printing consumable is configured to be compatible with fused deposition modeling (FDM) 3D printing, the matrix material is thermoplastic filament, and the thermoplastic filament comprises the following materials by mass percentage: The thermoplastic wire comprises 85-99.9% thermoplastic plastic and 0.1-15% multifunctional core-shell structure filler; the thermoplastic plastic wire is a coaxial structure including an inner core and an outer shell, wherein the mass percentage of the multifunctional core-shell structure filler in the inner core is 10-15%, and the mass percentage of the multifunctional core-shell structure filler in the outer shell is less than 2%.

[0011] Preferably, when the printing consumable is configured to be compatible with powder bed fusion 3D printing, the matrix material is thermoplastic powder, comprising thermoplastic powder and a multifunctional core-shell structure filler adsorbed onto the surface; the content of the multifunctional core-shell structure filler is 0.1-2% of the mass of the thermoplastic powder.

[0012] On the other hand, the present invention also provides a method for preparing the graphene-reinforced 3D printing material, wherein the multifunctional core-shell structure filler and matrix material are mixed and then subjected to corresponding subsequent processing; The preparation of the multifunctional core-shell structure packing includes the following steps: S1. Core surface activation: The microspheres in the core are acid-washed or plasma-treated to enrich their surface with active groups; S2. Catalyst loading: The treated core microspheres are immersed in a solution containing a transition metal catalyst, and a catalyst precursor layer is formed on their surface by adsorption or sol-gel method. After drying and calcination, they are converted into metal or metal oxide nanoparticles. S3. In-situ growth of graphene: The core microspheres loaded with catalyst are placed in a chemical vapor deposition device, and carbon source gas is introduced at 600-1000℃ in a hydrogen and inert gas atmosphere for 10-60 min to grow a few layers of graphene intermediate layer on the core surface. S4. Active outer shell encapsulation: An aluminum oxide or silicon dioxide outer shell layer is deposited on the surface of the graphene interlayer using atomic layer deposition; or a solution method is used to graft silane coupling agents or polymer monomers containing reactive functional groups onto the surface of the graphene interlayer to form a polymer encapsulation outer shell layer.

[0013] Preferably, the preparation method of the graphene-reinforced 3D printing material when the printing consumables are configured to be adapted for photopolymerization 3D printing process includes the following steps: Multifunctional core-shell structured filler, light diffusion modifier, photoinitiator, dispersant and photosensitive resin are mixed and first stirred in a planetary centrifuge at 500-2000 rpm for 10-30 min. Then, the mixture is ultrasonically treated in an ice-water bath at 500-1000W power for 15-45 min by an ultrasonic cell disruptor to obtain a uniform and stable printable slurry.

[0014] Preferably, the method for preparing the graphene-reinforced 3D printing material when the printing consumables are configured to be adapted for the fused deposition modeling (FDM) 3D printing process includes the following steps: After premixing the multifunctional core-shell structure filler with thermoplastic granules, the mixture is melt-blended and granulated using a twin-screw extruder at a temperature 20-50°C higher than the melting point of the matrix. The resulting masterbatch is then drawn, cooled, and shaped using a single-screw extruder to obtain composite wires of a specified diameter.

[0015] Thirdly, the present invention also provides an application of a graphene-reinforced 3D printing material, wherein the printing material is used for integrated structural and functional 3D printing, comprising the following steps: 3D printing molding: Based on the selected composite material system, solid parts are printed using the corresponding 3D printing process and equipment based on the digital model; Pyrolysis-induced pore treatment: The printed solid part is subjected to programmed temperature rise heat treatment under inert gas protection, with a heating rate of 2-5℃ / min, heated to the decomposition or softening temperature of the core material of the multifunctional core-shell structure filler and held for 1-3 hours, so that the core material is decomposed or removed to form a three-dimensional interconnected micro-nano pore network inside the solid part. Functional medium infusion: Under vacuum or pressure assistance, at least one functional medium selected from phase change material, liquid metal, self-healing monomer or magnetic fluid is infused into the micro-nano channel network and then cured or encapsulated to obtain an integrated component with corresponding functions.

[0016] Furthermore, the physical component also has structural load-bearing function and at least one additional function provided by the functional medium, such as thermal management, electrical conductivity, self-healing, or sensing.

[0017] Beneficial effects: This invention utilizes a core-shell filler structure consisting of a lightweight core, a graphene functional layer, and an active outer shell. The outer shell solves the industry-wide challenges of graphene dispersion and interfacial bonding; the core reserves space for post-functionalization; and the graphene layer efficiently provides functional properties. This invention, by adjusting the matrix system, allows the same core reinforcing filler to seamlessly adapt to three mainstream printing processes: photopolymerization, fused deposition modeling, and powder bed fusion, achieving multiple uses for a single material and greatly improving the versatility of the material platform and R&D efficiency. This invention uses nano-ceramic particles as an interface reinforcing agent, which act as rivets and stress transfer points between fibers and resins, while improving the stiffness and heat resistance of the matrix itself, thus strengthening the composite material as a whole from a microscopic perspective. Detailed Implementation

[0018] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection.

[0019] It should be noted that the technical solutions provided in the embodiments of the present invention are as follows: I. Multifunctional Core-Shell Structure Graphene Reinforced Composite Materials The composite material system of the present invention consists of a multifunctional core-shell structure filler and a matrix system adapted to a specific printing process.

[0020] Core-shell structured functional packing material: This packing material is a three-layer structured microsphere.

[0021] The core consists of hollow glass microspheres, hollow ceramic microspheres (such as alumina and silica), or thermally decomposable / chemically etchable polymer microspheres (such as polymethyl methacrylate (PMMA)), with a particle size range of 5-50 μm. Its main functions are to reduce the density of the composite material, regulate its rheological properties, and create internal space for subsequent post-processing.

[0022] Intermediate layer: This is a few-layer graphene layer (1-10 layers) grown in situ on the core surface through chemical vapor deposition or atomic layer deposition. This layer is the core functional layer that imparts excellent electrical conductivity, thermal conductivity, and mechanical reinforcement to the composite material.

[0023] Outer shell layer: A reactive encapsulation layer with a thickness of 10-200 nm, encapsulating the graphene layer. This layer is made of one or a combination of the following materials: silane coupling agent-grafted polymers, silica, and alumina. Firstly, it protects the graphene from mechanical damage during subsequent processing; secondly, through the active functional groups on its surface (such as amino, epoxy, and vinyl groups), it forms strong chemical bonds or physical entanglements with the printing substrate, greatly improving interfacial compatibility and stress transfer efficiency.

[0024] Suitable for matrix systems with multiple processes: Photocurable system: This system comprises the following materials by weight percentage: Photosensitive resin matrix: 90-95%, selected from one or a mixture of epoxy acrylate, polyurethane acrylate, and polyester acrylate.

[0025] Core-shell structure filler: 1-5%.

[0026] Light diffusion modifier: 0.1-0.5% of surface-modified nanodiamond or zirconium oxide nanoparticles, used to reduce excessive absorption and scattering of ultraviolet light by graphene, ensuring the curing depth and accuracy of the print.

[0027] Photoinitiator: 1-5% (relative to the weight of the resin matrix), selected from phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, 2-isopropylthioxanthrone, etc.

[0028] Dispersant and leveling agent: 0.5-2% (relative to the total slurry weight).

[0029] Fused deposition system: This system comprises the following materials by mass percentage: Thermoplastic matrix: 85-99.9%, selected from one or a mixture of polyamide, polycarbonate, polyetheretherketone, and polylactic acid.

[0030] Core-shell structure filler: 0.1-15%. To achieve higher performance, this composite material can be prepared as a coaxial composite filament, in which the inner core is a composite with a high filler content (10-15%), and the outer shell is a pure or low filler content (<2%) homogeneous matrix, with a filament diameter of 1.75±0.05mm or 2.85±0.05mm.

[0031] Powder bed melting system: This system is a composite powder in which the surface of the matrix powder (such as polyamide 12, particle size 20-80μm) is uniformly coated with core-shell structured filler through electrostatic adsorption and weak sintering, and the filler content is 0.1-2%.

[0032] II. Preparation methods of composite materials Preparation of core-shell structured fillers (layer-by-layer self-assembly-in-situ growth method): a. Core surface activation: Hollow microspheres are acid-washed or plasma-treated to enrich their surface with active groups such as hydroxyl groups.

[0033] b. Catalyst loading: The treated microspheres are immersed in a solution containing transition metal catalysts (such as nickel nitrate and ferric chloride), and a uniform catalyst precursor layer is formed on their surface by adsorption or sol-gel method. Then, they are dried and calcined to transform them into metal or metal oxide nanoparticles.

[0034] c. In-situ growth of graphene: Microspheres loaded with catalyst are placed in a chemical vapor deposition furnace and heated to 600-1000℃ in a hydrogen / argon atmosphere. A carbon source gas (such as methane or ethylene) is introduced and the reaction is carried out for 10-60 minutes to grow few layers of graphene on the core surface.

[0035] d. Active outer shell encapsulation: A layer of alumina or silicon dioxide is deposited on the graphene surface using atomic layer deposition; or a solution method is used to graft silane coupling agents or polymer monomers containing reactive functional groups onto the graphene surface to form a polymer encapsulation layer.

[0036] Preparation of printing materials: Photocurable slurry: The core-shell filler, light diffusion modifier, photoinitiator, dispersant and photosensitive resin are mixed according to the formula. First, the mixture is stirred in a planetary centrifuge at 500-2000 rpm for 10-30 minutes for preliminary mixing. Then, it is ultrasonically treated in an ice-water bath at 500-1000W power for 15-45 minutes by an ultrasonic cell disruptor to finally obtain a uniform and stable printable slurry with shear thinning properties.

[0037] Fused deposition modeling (FDM) wires: Core-shell fillers and thermoplastic granules are premixed in a high-speed mixer, then melt-blended and extruded using a co-rotating twin-screw extruder at a temperature 20-50°C above the matrix melting point. The resulting masterbatch is then drawn, cooled, traction, and wound into filaments using a single-screw extruder to control the filament diameter.

[0038] Powder bed melt composite powder: Dry mixing is carried out using a high-speed stirred ball mill, or wet mixing is carried out using solvent-assisted (such as ethanol) followed by spray drying, so that the core and shell fillers are uniformly and firmly attached to the surface of the matrix powder particles, and then sieved (such as 100 mesh) to obtain a composite powder with good flowability.

[0039] III. 3D Printing and Structural-Functional Integration Approach 3D printing process: Based on the selected material system, appropriate commercial or customized 3D printing equipment is used to print according to the preset digital model. Key process parameters need to be optimized. For example, in photopolymerization, the exposure time and power need to be adjusted according to the curing characteristics of the slurry; in fused deposition modeling, the printing temperature, layer thickness, and infill path need to be optimized to obtain good interlayer bonding.

[0040] Multifunctional post-processing: a. Pyrolysis-induced pores: For photopolymerized or fused deposition modeled components, a programmed temperature heat treatment is performed under an inert gas (nitrogen or argon) atmosphere. The heat treatment regime needs to be precisely controlled: the temperature is increased at a rate of 2-5°C / min to the decomposition or softening temperature of the core material (e.g., 300-450°C for polymer cores, and some ceramic cores require higher temperatures or chemical etching), and held at that temperature for 1-3 hours. During this process, the core material is decomposed or removed, while the stable cage-like structure formed by the graphene interlayer and the active shell is retained, thereby forming a three-dimensional interconnected micro / nano-scale network of pores inside the component.

[0041] b. In-situ infusion and encapsulation: Under vacuum or pressure assistance, functional fluids (such as paraffin-based phase change materials, liquid metals, self-healing monomers, and magnetic fluids) are infused into the aforementioned microchannel network. Subsequently, the functional medium is stabilized within the channels through curing, cooling, or interfacial reactions. The infusion port can be selectively sealed, ultimately resulting in an integrated component with active intelligent functions such as thermal management, conductivity, self-healing, or sensing.

[0042] Preparation Example 1 Core surface activation: 20g of hollow glass microspheres with an average particle size of 20μm (SiO2 content >85%) were placed in a 1M dilute hydrochloric acid solution and sonicated for 30min. They were then washed with deionized water until neutral and dried at 80℃. Subsequently, they were placed in an oxygen plasma treatment machine and treated at 100W power for 5min to enrich the surface with hydroxyl groups.

[0043] Catalyst loading: The activated microspheres were immersed in a 0.1M nickel nitrate ethanol solution and stirred for 2 hours for adsorption. After filtration, they were dried in air at 60°C and then placed in a tube furnace and calcined at 400°C for 1 hour in a hydrogen / argon atmosphere (volume ratio 1:9) to decompose nickel nitrate into nickel oxide nanoparticles, which were uniformly attached to the surface of the microspheres.

[0044] In-situ graphene growth: Catalyst-loaded microspheres were transferred to a chemical vapor deposition furnace and heated to 850°C under a hydrogen / argon atmosphere. Methane (flow rate 20 sccm) was introduced as a carbon source, and the reaction was carried out for 30 min. After natural cooling, microspheres with five layers of few-layer graphene on their surface were obtained.

[0045] Active outer shell encapsulation: Using atomic layer deposition (ALD) with trimethylaluminum and water as precursors, an alumina film with a thickness of approximately 50 nm was deposited on the surface of the microspheres as a reactive encapsulation outer shell layer. This resulted in a core-shell structured filler.

[0046] Preparation Example 2 The difference from Preparation Example 1 is as follows: Core: Thermally decomposable polymethyl methacrylate microspheres with an average particle size of 10 μm.

[0047] Catalyst: Ferric chloride solution is used.

[0048] Outer shell: Using a solution method, the microspheres after graphene growth are dispersed in ethanol, and 3-aminopropyltriethoxysilane (APTES) is added. The mixture is refluxed at 80°C for 4 hours to graft amino active functional groups onto the surface of the microspheres, forming a polymer encapsulation shell.

[0049] Example 1 Formula (percentage by weight): Photosensitive resin (epoxy acrylate): 92.5%, core-shell structured filler (from Preparation Example 1, core is 20 μm glass microspheres, shell is 50 nm alumina): 2.0%, light diffusion modifier (surface carboxylated nanodiamond, average particle size 50 nm): 0.5%, photoinitiator (TPO): 3%, and dispersant (BYK-180): 1%.

[0050] Preparation method: The core-shell filler, light diffusion modifier, photoinitiator, dispersant and photosensitive resin are mixed. The mixture is first stirred at 1500 rpm for 20 minutes in a planetary centrifuge for initial mixing. Then it is ultrasonically treated in an ice-water bath at 800W power for 30 minutes using an ultrasonic cell disruptor to finally obtain a uniform and stable printable slurry with shear thinning properties.

[0051] The resulting slurry was subjected to a shear rate of 30 s at 25°C. -1The viscosity under the given conditions was 2800 mPa·s (test standard: ASTM D4287), exhibiting good shear thinning behavior; no visible stratification was observed in the 7-day static settling test.

[0052] Example 2 The difference from Example 1 is as follows: Formula (percentage by weight): Photosensitive resin (polyurethane acrylate): 90.0%, core-shell structured filler B (from preparation example 2, core is 10μm PMMA microspheres, shell is APTES graft layer): 4.0%, light diffusion modifier (zirconia nanoparticles): 0.5%, photoinitiator (Irgacure819): 4%, dispersant (EFKA-4310): 1.5%.

[0053] The resulting slurry was subjected to a shear rate of 30 s at 25°C. -1 The viscosity under the given conditions was 3500 mPa·s, exhibiting good shear-thinning behavior; no visible stratification was observed during the 7-day static sedimentation experiment.

[0054] Example 3 formula: Matrix powder: polyamide 12, average particle size 55μm, sphericity >95%.

[0055] Core-shell structured filler: derived from Preparation Example 1, with a content of 0.5 wt.%.

[0056] Preparation method: Dry mixing for 120 seconds using a Henschel mixer and a high-speed stirring ball mill at 1000 rpm ensures that the core-shell filler adheres evenly and firmly to the surface of the matrix powder particles. The resulting composite powder is then passed through a 100-mesh sieve to obtain a free-flowing powder.

[0057] The resulting powder has the following properties: Hall flow rate 28 s / 50 g (test standard: ASTM D1895), resistivity 10 Ω·cm. 9 Ω·cm (Test standard: ASTM D257 (Powder resistivity test fixture)).

[0058] Example 4 The difference from Example 3 is: Formula: Matrix powder: polyamide 12, average particle size 55μm, sphericity >95%.

[0059] Core-shell structured filler: from preparation example 1, with a content of 1.5 wt.%.

[0060] The resulting powder exhibits a flow rate of 32 s / 50 g and an absorption rate at 1064 nm laser that is approximately 40% higher than that of pure PA12.

[0061] Example 5 formula: Matrix: Polycarbonate (PC).

[0062] Core-shell structured filler (from Example 1): content 4.0 wt.%.

[0063] Preparation method: Core-shell fillers and thermoplastic granules are premixed in a mixer, then melt-blended and extruded into granules using a co-rotating twin-screw extruder at a temperature of 260-280℃. The resulting masterbatch is then drawn, cooled, traction, and wound into wires using a single-screw extruder to produce homogeneous composite wires with a diameter of 1.75±0.03mm.

[0064] The resulting wire has a tensile strength at break of 62 MPa, and the testing standard is ASTM D638.

[0065] Example 6 The difference from Example 5 is as follows: Matrix: Polyamide 6 (PA6).

[0066] Core-shell structured filler (from Example 1): content 8.0 wt.%.

[0067] The resulting wire has a melt flow index of 18 g / 10 min and is tested according to ASTM D1238 (230℃ / 2.16 kg).

[0068] Example 7 The difference from Example 5 is as follows: Matrix: Polyetheretherketone (PEEK).

[0069] Core-shell structured filler (from Example 1): content of 12 wt.%.

[0070] Preparation method: Coaxial composite wires with a diameter of 1.75 mm were prepared using coaxial co-extrusion technology. The inner core is a composite of PEEK and filler A (filler content 12 wt.%), and the outer shell is pure PEEK, with an inner core / outer shell cross-sectional area ratio of 6:4.

[0071] Comparative Example 1 The difference from Example 1 is that graphene nanosheets with a diameter of 10 μm and a thickness of 2 nm are used instead of the core-shell structure filler from Preparation Example 1.

[0072] The resulting slurry was subjected to a shear rate of 30 s at 25°C. -1 The viscosity under the given conditions was 12000 mPa·s, exhibiting strong thixotropy and poor flowability. After ultrasonic dispersion and standing for 2 hours, significant filler agglomeration and sedimentation occurred, making printing impossible.

[0073] Comparative Example 2 The difference from Example 1 is that the core-shell structure filler is not encapsulated with an active outer shell.

[0074] The result was obtained at 25°C and a shear rate of 30 s. -1 The viscosity under the given conditions is 3,200 mPa·s, but the storage stability is poor, with slight sedimentation occurring after 24 hours. The tensile strength of the printed product is 52 MPa, and the thermal resistance is 10.5 K / W.

[0075] Comparative Example 3 The difference from Example 1 is that spherical alumina powder with an average particle size of 5 μm is used instead of the core-shell structure filler from Preparation Example 1.

[0076] After printing, the thermal resistance is 9.8 K / W, and the volume resistivity is >10¹. 4 Ω·cm (insulation).

[0077] Comparative Example 4 The difference from Example 3 is that graphene nanosheets with a diameter of 10 μm and a thickness of 2 nm of equal mass are mixed with PA12 powder at low speed in a drum for 30 min.

[0078] The graphene sheets and PA12 powder clump together and cannot be mixed evenly. The powder has poor flowability, making it unsuitable for powder spreading and printing.

[0079] Comparative Example 5 The difference from Example 3 is that the core-shell structure filler is from Preparation Example 1, with a content of 5 wt.%.

[0080] The powder flow rate is >50s / 50g, indicating poor flowability and noticeable scratches during powder spreading. The printed product has a rough surface and a tensile strength of 40MPa.

[0081] Comparative Example 6 The difference from Example 5 is that the core-shell structure filler from Preparation Example 1 is replaced with graphene nanosheets with a diameter of 10 μm and a thickness of 2 nm.

[0082] During the twin-screw extrusion granulation process, the material melt strength is low, making it prone to cracking. The resulting wire has an uneven diameter, a rough surface with nodules, and frequent nozzle clogging during printing.

[0083] Comparative Example 7 The difference from Example 6 is that the core-shell structure filler from Preparation Example 1 is replaced with graphene nanosheets with a diameter of 10 μm and a thickness of 2 nm.

[0084] The wire is brittle and easily breaks when bent. The printed product has a shielding effectiveness of 18dB, a thermal conductivity of 0.40W / (m·K), and a 15% decrease in tensile strength.

[0085] Comparative Example 8 The difference from Example 7 is that the preparation method is the same as in Example 5.

[0086] The high stiffness of the filament causes significant wear on the filament feed rollers. This results in a noticeable increase in nozzle resistance during printing, leading to a grainy texture and stringy appearance on the printed parts.

[0087] Application Example 1 Application method: Using the slurry prepared in Example 1, a chip heat sink with microfins and internal channels with a thickness of 150μm was printed on a surface projection photopolymerization printer with a layer thickness of 30μm.

[0088] Post-treatment: subjected to two UV curing cycles and 60℃ heat drying for 2 hours.

[0089] Application component performance: Dimensional accuracy: Fin thickness deviation <3.5%. Inspection method: Optical projector (ISO2768).

[0090] Thermal properties: Thermal resistance 8.2 K / W. Testing standard: ASTM D5470 (simulated heat source method).

[0091] Mechanical properties: Tensile strength 65 MPa, flexural strength 98 MPa. Testing standards: ASTM D638, D790.

[0092] Application Example 2 Using the paste prepared in Example 2, an insulating substrate containing embedded three-dimensional spiral grooves was printed. After being processed as in Application Example 1, a low-melting-point solder alloy was poured into the grooves under vacuum to form a three-dimensional conductive coil.

[0093] Application component performance: Electrical performance: Coil resistance 0.8Ω, aging change rate <1% after 100h. Testing method: Continuous monitoring with a digital multimeter.

[0094] Structural integration: No failures were observed during vibration testing (10-500Hz). Testing standard: GB / T2423.10.

[0095] Application Example 3 Using the powder obtained in Example 3, a batch of precision transmission gears were printed on a selective laser sintering device using standard nylon parameters (laser power 30W, scanning speed 5m / s).

[0096] Application component performance: Dimensional accuracy: within ±0.1mm.

[0097] Antistatic properties: Static charge decays to 10% in less than 2 seconds. Testing standard: ANSYS / ESDS11.11.

[0098] Mechanical properties: Tensile strength 46 MPa. Testing standard: ASTM D638.

[0099] Application Example 4 Using the powder prepared in Example 4, a thin-walled hydraulic connector with a wall thickness of 0.6 mm was printed at a laser power of 24 W, a 20% reduction. The low power was intended to reduce thermal stress and improve dimensional accuracy.

[0100] Application component performance: Print quality: 0.6mm wall thickness, actual measurement 0.62±0.05mm.

[0101] Mechanical properties: Burst pressure 12.8 MPa. Testing standard: ISO 1167 (hydrostatic burst test).

[0102] Application Example 5 Using the filament prepared in Example 5, a hollowed-out load-bearing bracket for a mechanical device was printed on a fused deposition modeler with a nozzle temperature of 270°C and a heated bed of 100°C.

[0103] Application component performance: Printing process performance: Smooth filament feeding, no clogging.

[0104] Mechanical properties: Compressive strength 78 MPa. Testing standard: ASTM D695.

[0105] Application Example 6 A mobile phone frame model with a wall thickness of 2mm was printed using the filament prepared in Example 6.

[0106] Application component performance: Electromagnetic shielding effectiveness: 32dB at 1GHz. Testing standard: ASTM D4935.

[0107] Thermal conductivity: 0.95 W / (m·K). Testing standard: ASTM E1461.

[0108] Application Example 7 Using the filament prepared in Example 7, a sliding bearing was printed in a high-temperature fused deposition modeling printer with a nozzle temperature of 410°C and a heated bed temperature of 130°C.

[0109] Application component performance: Tribological properties: coefficient of friction 0.28, wear rate 3.2×10⁻⁶ -6 mm³ / (N·m). Testing standard: ASTM G77.

[0110] Heat resistance: Heat distortion temperature 285℃. Testing standard: ASTM D648 (1.82MPa).

[0111] Print quality: Smooth outer surface.

[0112] In conclusion: Comparative Example 1 shows that uncoated graphene agglomerates, leading to excessively high slurry viscosity and sedimentation, making printing impossible. In contrast, Examples 1-2, using core-shell structured fillers, produced slurry with moderate and stable viscosity, demonstrating the core value of core-shell structures in solving dispersion problems.

[0113] Compared with Example 1, Comparative Example 2 showed a 20% decrease in tensile strength and a 28% increase in thermal resistance under the same filler type and content. This directly demonstrates the decisive role of the reactive shell layer in improving interfacial bonding and optimizing stress and heat conduction.

[0114] Comparative Example 3 uses traditional alumina, which can only improve thermal conductivity. However, Example 2 and Application Example 2 achieve integrated manufacturing of thermal conductivity, electrical conductivity, and structural support, demonstrating the multifunctional integration potential of core-shell graphene fillers and surpassing the limitations of single-function fillers.

[0115] The physical mixing in Comparative Example 4 resulted in powder failure, while Examples 3-4 achieved uniform adhesion of fillers and good powder flowability through dry or wet processes, verifying the unique advantages of the electrostatic adsorption adhesion composite method.

[0116] Comparative Example 5, by increasing the filler content by 5.0 wt.%, resulted in deteriorated powder flowability and decreased component performance. This contrasts with Examples 3-4, which achieved good results in the 0.1-2 wt.% range, demonstrating that the content range in the claims is the optimal choice for balancing functionality and processability, and is not a simple linear extrapolation.

[0117] Application Example 3 achieves excellent antistatic properties while basically maintaining the original mechanical properties and appearance of PA12, solving the long-standing performance trade-off problem in the industry.

[0118] Comparative Example 6 further confirms that uncoated graphene disrupts the rheological properties of the polymer melt, leading to processing failure. The successful implementation of Examples 5-7 establishes the necessity of core-shell structures in fused deposition processes.

[0119] Comparative Example 7, with the same addition amount, exhibited shielding and thermal conductivity performance less than 60% of that of Example 6 of the present invention, and its mechanical properties also decreased. This highlights the ultra-high functional enhancement efficiency brought about by the excellent dispersion and good interface of the core-shell structure filler.

[0120] Comparative Example 8 shows that simply increasing the filler content in homogeneous filaments can impair printability and surface quality. The coaxial filament used in Example 7 cleverly achieves excellent print smoothness and part surface finish by utilizing a pure resin shell, while maintaining a high core filler content through structural design. This is a non-obvious yet remarkably effective creative design.

[0121] This invention, through an original core-shell structure filler design, combined with specialized composite methods for different processes and an optimized parameter system, constructs a novel, cross-platform applicable high-performance 3D printing material solution. Experimental data fully demonstrates that this solution effectively solves long-standing technical bottlenecks.

[0122] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A graphene-reinforced 3D printing material, characterized in that, It includes a multifunctional core-shell structure filler and a matrix material; the multifunctional core-shell structure filler includes a core, a graphene intermediate layer encapsulating the core, and a reactive encapsulation shell encapsulating the graphene intermediate layer; the matrix material includes one of photocurable resin slurry, thermoplastic plastic wire, and thermoplastic plastic powder.

2. The graphene-reinforced 3D printing material according to claim 1, characterized in that, The core comprises one of hollow glass microspheres, hollow ceramic microspheres, and thermally decomposable polymer microspheres, and the particle size of the core is 5-50 μm; The number of layers in the graphene intermediate layer is 1-10; The reactive encapsulation shell layer is made of one or more of the following materials: silane coupling agent-grafted polymer, silicon dioxide, and aluminum oxide, and the thickness of the reactive encapsulation shell layer is 10-200 nm.

3. The graphene-reinforced 3D printing material according to claim 2, characterized in that, When the printing consumables are configured to be compatible with photopolymer 3D printing technology, the matrix material is a photopolymer resin slurry, and the photopolymer resin slurry comprises the following materials by mass percentage: 90-95% photosensitive resin, 1-5% multifunctional core-shell structure filler and 0.1-0.5% light diffusion modifier; The light diffusion modifier includes surface-modified nanodiamond or zirconium oxide nanoparticles.

4. The graphene-reinforced 3D printing material according to claim 2, characterized in that, When the printing consumable is configured to be compatible with the fused deposition modeling (FDM) 3D printing process, the matrix material is thermoplastic filament, and the thermoplastic filament comprises the following materials by mass percentage: The thermoplastic wire comprises 85-99.9% thermoplastic plastic and 0.1-15% multifunctional core-shell structure filler; the thermoplastic plastic wire is a coaxial structure including an inner core and an outer shell, wherein the mass percentage of the multifunctional core-shell structure filler in the inner core is 10-15%, and the mass percentage of the multifunctional core-shell structure filler in the outer shell is less than 2%.

5. The graphene-reinforced 3D printing material according to claim 2, characterized in that, When the printing consumables are configured to be compatible with powder bed fusion 3D printing, the matrix material is thermoplastic powder, comprising thermoplastic powder and a multifunctional core-shell structure filler adsorbed onto the surface; the content of the multifunctional core-shell structure filler is 0.1-2% of the mass of the thermoplastic powder.

6. A method for preparing a graphene-reinforced 3D printing material according to any one of claims 1-5, characterized in that, The multifunctional core-shell structure filler and matrix material are mixed, and then corresponding follow-up treatments are performed. The preparation of the multifunctional core-shell structure packing includes the following steps: S1. Core surface activation: The microspheres in the core are acid-washed or plasma-treated to enrich their surface with active groups; S2. Catalyst loading: The treated core microspheres are immersed in a solution containing a transition metal catalyst, and a catalyst precursor layer is formed on their surface by adsorption or sol-gel method. After drying and calcination, they are converted into metal or metal oxide nanoparticles. S3. In-situ growth of graphene: The core microspheres loaded with catalyst are placed in a chemical vapor deposition device, and carbon source gas is introduced at 600-1000℃ in a hydrogen and inert gas atmosphere for 10-60 min to grow a few layers of graphene intermediate layer on the core surface. S4. Active outer shell encapsulation: An aluminum oxide or silicon dioxide outer shell layer is deposited on the surface of the graphene interlayer using atomic layer deposition; or a solution method is used to graft silane coupling agents or polymer monomers containing reactive functional groups onto the surface of the graphene interlayer to form a polymer encapsulation outer shell layer.

7. The preparation method according to claim 6, characterized in that, The preparation method of the graphene-reinforced 3D printing material when the printing consumables are configured to be compatible with photopolymerization 3D printing process includes the following steps: Multifunctional core-shell structured filler, light diffusion modifier, photoinitiator, dispersant and photosensitive resin are mixed and first stirred in a planetary centrifuge at 500-2000 rpm for 10-30 min. Then, the mixture is ultrasonically treated in an ice-water bath at 500-1000W power for 15-45 min by an ultrasonic cell disruptor to obtain a uniform and stable printable slurry.

8. The preparation method according to claim 6, characterized in that, The preparation method of the graphene-reinforced 3D printing material when the printing consumables are configured to be adapted to the fused deposition modeling (FDM) 3D printing process includes the following steps: After premixing the multifunctional core-shell structure filler with thermoplastic granules, the mixture is melt-blended and granulated using a twin-screw extruder at a temperature 20-50°C higher than the melting point of the matrix. The resulting masterbatch is then drawn, cooled, and shaped using a single-screw extruder to obtain composite wires of a specified diameter.

9. An application of the graphene-reinforced 3D printing material according to any one of claims 1-5, characterized in that, The process of 3D printing the aforementioned printing material to achieve integrated structural and functional design includes the following steps: 3D printing molding: Based on the selected composite material system, solid parts are printed using the corresponding 3D printing process and equipment based on the digital model; Pyrolysis-induced pore treatment: The printed solid part is subjected to programmed temperature rise heat treatment under inert gas protection, with a heating rate of 2-5℃ / min, heated to the decomposition or softening temperature of the core material of the multifunctional core-shell structure filler and held for 1-3 hours, so that the core material is decomposed or removed to form a three-dimensional interconnected micro-nano pore network inside the solid part. Functional medium infusion: Under vacuum or pressure assistance, at least one functional medium selected from phase change material, liquid metal, self-healing monomer or magnetic fluid is infused into the micro-nano channel network and then cured or encapsulated to obtain an integrated component with corresponding functions.

10. The application according to claim 9, characterized in that, The physical component simultaneously possesses structural load-bearing function and at least one additional function provided by the functional medium, such as thermal management, electrical conductivity, self-healing, or sensing.