Composition for 3D printing, filament and preparation method and application thereof

Abstract

The invention discloses a composition for 3D printing, a filament and a preparation method and application thereof. Firstly, the invention provides a composition for 3D printing, and the composition comprises chopped montmorillonite fibers and thermoplastic resin. Secondly, single-component filaments or gradient filaments are obtained from the composition through an extrusion molding method. Then, single-component wires are adopted in sequence, and the dielectric material with the required dielectric property is obtained by controlling the 3D printing technology; or gradient filaments are adopted, and the gradient dielectric material is obtained through the 3D printing technology. The dielectric constant is regulated and controlled based on the graphene layer thickness of the chopped montmorillonite fiber, and the functional dielectric material with mechanical properties, spatial uniformity and gradient distribution of the dielectric constant can be prepared on the premise of not changing the filler proportion through spatial programming stacking of melt extrusion and a 3D printing process.

Description

Technical Field

[0001] This invention belongs to the technical field of thermoplastic resin compositions, specifically relating to a composition for 3D printing, a filament, a method for preparing the same, and its application in gradient dielectric materials. Background Technology

[0002] Functionally graded dielectric materials (FGDMs) play a crucial role in impedance matching, field intensity control, and multifunctional integration due to their programmable spatial dielectric constant distribution. Traditional homogeneous polymer materials (such as epoxy resins and polyetheretherketones) have fixed dielectric constants, making them unsuitable for complex applications. Current technologies primarily achieve dielectric gradient construction by controlling the filler phase in the polymer matrix. Typical methods include: adjusting the volume fraction of high-dielectric-constant fillers (such as barium titanate, strontium titanate ceramics, or carbon nanotubes and graphene); using external fields to induce the directional arrangement of sheet / fibrous fillers to construct anisotropic dielectric responses; and employing multi-component filler composites. However, these methods suffer from a fundamental flaw due to the strong coupling effect of dielectric and mechanical properties. Changes in filler content or properties lead to variations in their interaction with the polymer matrix, resulting in uneven spatial stress distribution and easy delamination between layers, creating an inherent contradiction between dielectric function control and structural stability. Meanwhile, the direct dispersion of nanomaterials such as graphene in polymers is prone to agglomeration, which affects the overall performance of the material. Therefore, it is necessary to develop a novel dielectric control strategy to achieve controllable gradient adjustment of the dielectric constant while ensuring uniform dispersion of fillers, stable overall material structure, and uniform mechanical properties, and to apply it to industrial production.

[0003] Chopped glass fiber reinforced polymers (GFRPs), as representatives of lightweight structural materials, have been widely used in automotive parts, wind turbine blades, and electronic packaging. However, while intrinsic GFRPs possess excellent stability and mechanical properties, their applications in electrical, thermal, and multifunctional composite materials are relatively limited. For example, glass fibers are difficult to interact effectively with electric, magnetic, and optical fields, thus limiting their functional applications. Developing glass fiber materials with tunable dielectric constants through functional modification (such as composites with graphene) holds promise for overcoming these performance limitations and technical barriers, achieving structural-functional integration. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a novel dielectric constant control strategy. This involves using CVD (Continuous Chemical Deposition) to coat the surface of fibers (such as glass fibers) with several to dozens of layers of graphene (this novel composite material is called "graphene fiber"). By adjusting the thickness of this graphene skin, the dielectric constant of the polymer-based material can be controlled without altering the fiber filling ratio. Fused deposition modeling (FDM) 3D printing technology enables a spatially programmable distribution of the material's dielectric constant. The nanometer to submicron thickness of the graphene does not affect the original preparation and processing of chopped fibers, nor does it affect the macroscopic structure and mechanical properties of the chopped fiber-reinforced polymer material. Simultaneously, the graphene skin imparts the functional property of adjustable dielectric constant to the fibers (such as glass fibers). Therefore, graphene and fibers (such as glass fibers) exhibit excellent process and system compatibility. The core-shell structure formed by their combination holds promise for overcoming the technical barrier of the incompatibility between continuously adjustable dielectric constant and structural stability, leading to practical applications. Furthermore, this composite strategy, by utilizing rigid carriers such as fibers (e.g., glass fibers), is expected to suppress the aggregation of graphene layers in the polymer matrix, establish an ordered dielectric network structure, and provide new ideas for graphene dispersion technology.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a composition for 3D printing.

[0006] The composition for 3D printing provided by this invention includes short-cut montmorillonite fibers and thermoplastic resin.

[0007] Furthermore, the mass ratio of the short-cut montmorillonite fiber to the thermoplastic resin can be 1:(1-10).

[0008] Furthermore, the short-cut montmorillonite fiber is obtained by cutting montmorillonite fiber or montmorillonite fiber fabric; the length of the short-cut montmorillonite fiber can be 100-200 μm.

[0009] Furthermore, the short-cut graphene fiber comprises: fibers and a graphene layer formed on the surface of the fibers.

[0010] The fibers include, but are not limited to: glass fiber, alumina fiber, boron nitride fiber, etc.

[0011] The diameter of the fiber is 3-10 μm. The fiber diameter can also be adjusted according to actual needs.

[0012] The graphene fiber used in this invention can be prepared by referring to the methods disclosed in the prior art (such as the method described in CN 108545966 A), such as using chemical vapor deposition (CVD) to form a graphene layer on the fiber surface to obtain graphene fiber.

[0013] By controlling the CVD deposition time during the preparation process, graphene-coated fibers of different thicknesses (or different numbers of graphene layers) can be obtained.

[0014] The thickness (or number of graphene layers) of the graphene fiber is related to its resistance. Generally, as the thickness of the graphene layer increases, the resistance of the graphene fiber decreases. This is because more graphene layers mean more conductive channels. Since a single layer of graphene has good conductivity, when multiple layers of graphene are stacked, electrons can jump and transport between different layers, greatly increasing the probability of electron transport and thus reducing resistance. The resistance of the graphene fiber is also closely related to its dielectric constant. When the resistance of the graphene fiber is low, it means that electron transport within it is smoother and the electron mobility is high, which usually corresponds to a higher dielectric constant. Therefore, the dielectric constant can be controlled by adjusting the thickness of the graphene layer in the graphene fiber; within a certain range, the greater the thickness of the graphene layer, the higher the dielectric constant of the corresponding graphene fiber.

[0015] Furthermore, the thickness of the graphene layer in the graphene fiber or graphene fiber fabric described in this invention can be 0.335-16.75 nm, or the number of graphene layers can be 1-50.

[0016] Furthermore, the sheet resistivity of the montmorillonite fiber fabric can be 10-1000 Ω·sq. -1 .

[0017] According to an embodiment of the present invention, the short-cut montmorillonite fiber is a short-cut montmorillonite glass fiber, and the thickness of the graphene layer in the short-cut montmorillonite glass fiber can be 0.335-16.75 nm or the number of graphene layers can be 1-50 layers. The sheet resistivity of the montmorillonite glass fiber fabric can be 10-1000 Ω·sq. -1 Those skilled in the art can select any surface resistance within the above range, such as 10 Ω·sq, according to actual needs. -1 100 Ω·sq -1 400 Ω·sq -1 600 Ω·sq -1 1000 Ω·sq -1 wait.

[0018] According to an embodiment of the present invention, the short-cut montmorillonite glass fiber is obtained by cutting montmorillonite glass fiber fabric into small pieces and then thoroughly pulverizing it using an ultracentrifugal grinder.

[0019] The graphene glass fiber comprises: glass fiber and a graphene layer formed on the surface of the glass fiber.

[0020] The glass fibers have a diameter of 5-10 μm. The length and diameter of the glass fibers can also be adjusted according to actual needs. The glass fiber fabric is woven from bundles of glass fibers, and the length can be adjusted according to actual needs.

[0021] The graphene glass fiber used in the embodiments of the present invention can be prepared by methods disclosed in the prior art (such as the method described in CN108545966 A), such as chemical vapor deposition (CVD) to form a graphene layer on the surface of the glass fiber to obtain the graphene glass fiber.

[0022] Furthermore, the thermoplastic resin may be selected from at least one of the following: polyetheretherketone (PEEK), nylon (PA), ABS (acrylonitrile-butadiene-styrene copolymer), and TPU (thermoplastic polyurethane elastomer).

[0023] Furthermore, the filament composition for 3D printing may also consist solely of short-cut montmorillonite fibers and thermoplastic resin.

[0024] According to one embodiment of the present invention, the short-chopped montmorillonite fiber is short-chopped montmorillonite glass fiber, the thermoplastic resin is polyetheretherketone (powder), and the mass ratio of the short-chopped montmorillonite glass fiber to polyetheretherketone (powder) in the composition for 3D printing is 3:7.

[0025] In a second aspect, the present invention provides a method for manufacturing filaments using the composition described in the first aspect.

[0026] The method for manufacturing filaments using the composition described in the first aspect provided by the present invention includes the following steps: The composition is used to obtain single-component filaments or gradient filaments by extrusion molding.

[0027] Furthermore, the extrusion molding is melt extrusion molding.

[0028] Furthermore, the melt extrusion molding is carried out in a twin-screw extruder, with the extruder heating chamber operating at a temperature of 350-400°C. o C. Control the feed rate to 8-20 g / min and the screw speed to 8-20 g / min.

[0029] Furthermore, the method also includes a pretreatment step of drying the filament composition, specifically as follows: after the filament composition is mixed evenly, it is placed in an oven and dried at 80-120°C. o Place at a temperature of C for 4-12 hours to dry out the moisture.

[0030] Furthermore, the preparation method of the single-component filament is as follows: a composition consisting of short-chopped graphene fibers with a graphene layer thickness and thermoplastic resin is added into the feed barrel of a twin-screw extruder to obtain a single-component filament.

[0031] Furthermore, the preparation method of the gradient filament is as follows: the composition of short-cut montmorillon fibers with different graphene layer thicknesses and thermoplastic resin is added sequentially and continuously into the feed barrel of a twin-screw extruder in order of graphene layer thickness from large to small (resistance of short-cut montmorillon fibers from small to large) or from small to large (resistance of short-cut montmorillon fibers from large to small) to obtain gradient filaments.

[0032] According to an embodiment of the present invention, a mixed powder containing SGF-10, SGF-100, SGF-400, SGF-600 and SGF-1000 is added sequentially to obtain a gradient filament named SGF-10-100-400-600-1000 / PEEK.

[0033] Furthermore, the method also includes the following steps: after the obtained filaments are passed through a blower cooling device and a diameter measuring instrument, they are connected and collected in a traction winding device. By adjusting the traction speed of the traction machine, the diameter of the filaments is controlled within the range of 1.75-1.85 mm.

[0034] Thirdly, the present invention provides single-component filaments or gradient filaments prepared by the method described in the second aspect.

[0035] Fourthly, the present invention provides a method for preparing gradient dielectric materials using the filament 3D printing described in the third aspect.

[0036] The method for preparing gradient dielectric materials using the aforementioned filament 3D printing provided by this invention includes the following steps: By sequentially using single-component filaments and controlling the 3D printing process, a gradient dielectric material with the desired dielectric properties can be obtained. Alternatively, gradient dielectric materials with the desired dielectric properties can be obtained by using gradient filaments and 3D printing technology.

[0037] Furthermore, the controlled 3D printing process specifically involves uniformly printing a single-component filament to a certain thickness through the nozzle of a 3D printer, pausing printing, replacing it with another single-component filament, and continuing printing. The filament can be changed continuously according to the gradient dielectric constant distribution requirements until printing is completed, thereby obtaining the desired gradient dielectric material. The replacement sequence of the single-component filaments can be based on the gradient dielectric constant distribution requirements, and the single-component filaments can be replaced sequentially in order of decreasing or increasing thickness of the graphene layer in the short-cut montmorillonite fibers (resistance of the short-cut montmorillonite fibers increases).

[0038] Furthermore, according to one embodiment of the present invention, the parameters of the 3D printing are set as follows: printing temperature is 400-430°C. o C. The minimum layer thickness of the printhead is 0.2-0.3 mm, the printing speed is 1-8 mm / s, and the fill rate is 100%.

[0039] Fifthly, the present invention provides a gradient dielectric material prepared by the method described in the fourth aspect.

[0040] like Figure 3 As shown, the dielectric constant exhibits a gradient change with height as the material thickness increases, and the real part of ε is spatially adjustable within the range of 2-15. Next, the material was cut into 5 layers, and each layer was processed into tensile specimens. The tensile strength of each specimen was then tested. The results show that the tensile strength of each tensile specimen is basically consistent, indicating that the mechanical strength of each layer is relatively uniform.

[0041] This invention utilizes the control of the dielectric constant based on the graphene layer thickness of short-cut montmorillonite fibers. Through spatial programming stacking of melt extrusion and 3D printing processes, functional dielectric materials with mechanical properties, spatial uniformity, and gradient distribution of dielectric constant can be prepared without changing the filler ratio.

[0042] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention provides a novel functional filler system: a polymer composite material with short-cut graphene fibers as reinforcing filler is prepared, and its dielectric constant (ε) can be continuously adjusted by controlling the thickness of the graphene layers (number of layers: 1-50 layers). r ≈2-15).

[0043] (2) The present invention provides a novel graphene dispersion process: a short-cut graphene fiber filler system is constructed by using a traditional short-cut fiber reinforced polymer molding process. The fiber acts as a rigid carrier to suppress the aggregation of the graphene layer and achieve its uniform dispersion.

[0044] (3) This invention provides a novel gradient dielectric material construction strategy: based on graphene fiber fillers with different graphene layer thicknesses, functional dielectric materials with gradient dielectric constant distribution are prepared by melt extrusion and 3D printing processes, realizing the controllable programming of the spatial distribution of its dielectric constant, while the mechanical strength of each component remains uniform and stable. Figure 2 ). Attached Figure Description

[0045] Figure 1(a) Physical image of short-cut montmorillonite glass fiber SGF-10; (b) Physical image of SGF-10 / PEEK composite particles; (c) Physical image of SGF-10 / PEEK filaments; (d) SEM image of short-cut montmorillonite glass fiber SGF-10; (e) Cross-sectional SEM image of SGF-10 / PEEK filaments; (f) Cross-sectional SEM image of gradient dielectric material.

[0046] Figure 2 Tensile curves of single-component filaments prepared from chopped glass fibers and chopped montmorillonite glass fibers with different graphene thicknesses.

[0047] Figure 3 (a) Spatial distribution of dielectric constant of a square gradient dielectric material; (b) Curve of dielectric constant versus frequency obtained from testing five layers of a square gradient dielectric material; (c) Spatial distribution of tensile strength of a gradient dielectric material.

[0048] Figure 4 This is a cross-sectional SEM image of SGF-a / PEEK filament.

[0049] Figure 5 (a) SEM image of the cross section of SGF-a / PEEK filament; (b) SEM image of the cross section of SGF-10 / PEEK filament; (c) EDS elemental distribution mapping image of SGF-a / PEEK filament; (d) EDS elemental distribution mapping image of SGF-10 / PEEK filament. Detailed Implementation

[0050] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0051] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0052] The following examples use montmorillonite glass fiber fabrics (with a sheet resistivity of 5-1000 Ω·sq). -1 (Not equal) includes: glass fiber fabric and a graphene layer formed on the surface of the glass fiber fabric.

[0053] The glass fiber fabric is woven from glass fibers (5-10 μm in diameter); the thickness of the graphene layer is adjusted in the range of 1-50 layers.

[0054] The graphene glass fiber fabric can be prepared according to the method described in CN 108545966 A. During the preparation process, graphene glass fiber fabrics with different thicknesses of graphene layer coating can be obtained by changing the deposition time. Generally, as the thickness of the graphene layer increases, the sheet resistance of the graphene glass fiber fabric will decrease and the dielectric constant will increase.

[0055] If the surface resistance is 10 Ω·sq -1 The graphene glass fiber fabric has a deposited graphene layer thickness of approximately 50 layers. If the surface resistance is 100 Ω·sq -1 The graphene glass fiber fabric has a deposited graphene layer thickness of approximately 40 layers. For example, the surface resistance is 400 Ω·sq -1 The graphene glass fiber fabric has a deposited graphene layer that is approximately 15 layers thick. For example, the surface resistance is 600 Ω·sq -1 The graphene glass fiber fabric has a deposited graphene layer that is approximately 8 layers thick. If the surface resistance is 1000Ω·sq -1 The graphene glass fiber fabric has a deposited graphene layer that is approximately one layer thick.

[0056] Example 1: Preparation of single-component montmorillonite glass fiber composite polyetheretherketone filaments and gradient montmorillonite glass fiber composite polyetheretherketone filaments (1) Montmorillonite glass fiber fabric (surface resistivity of 5~1000 Ω·sq) -1 After being cut into small pieces (of varying sizes), the fibers were thoroughly pulverized using an ultracentrifugal grinder. The resulting fibers were then sieved sequentially through sieves with pore sizes of 200 μm and 100 μm to obtain short-chopped montmorillonite glass fibers with lengths of 100–200 μm. Figure 1 As shown in (a) (based on the corresponding fabric surface resistivity values ​​of 10, 100, 400, 600, and 1000 Ω·sq), -1 They were named SGF-10, SGF-100, SGF-400, SGF-600, and SGF-1000, respectively. Figure 1 Image (d) shows a scanning electron microscope image of short-cut montmorillonite glass fiber.

[0057] (2) Short-cut montmorillonite glass fibers and polyetheretherketone powder (the company providing this product: Jilin Zhongyan Polymer Materials Co., Ltd., product model: 550PF, specification: granular powder with a diameter of about 50μm) were mixed in a rotary mixer at a mass ratio of 3:7 for 12 hours. The resulting homogeneous mixture was placed in an oven and dried at 120°C. oPlace at C temperature for 4 hours to dry out the moisture. A picture of the SGF-10 / PEEK complex particles is shown below. Figure 1 As shown in (b).

[0058] (3) Preparation of single-component filaments The mixed powder obtained in step 2 is added into the feed barrel of a twin-screw extruder, and the operating temperature of the extruder heating chamber is set to 380°C. o C. By controlling the feed rate at 12 g / min and the screw speed at 10 g / min, single-component montmorillonite glass fiber composite polyetheretherketone filaments are obtained, such as... Figure 1 As shown in (c) (named SGF-10 / PEEK, SGF-100 / PEEK, SGF-400 / PEEK, SGF-600 / PEEK, and SGF-1000 / PEEK respectively). Figure 1 Image (e) shows a cross-sectional scanning electron microscope (SEM) image of short-cut montmorillonite glass fiber composite polyetheretherketone (SGF-10 / PEEK) filaments. The filaments were connected and collected in a traction winding device after passing through a blower cooling unit and a diameter gauge. The filament diameter was controlled within the range of 1.75–1.85 mm by adjusting the traction speed of the traction machine.

[0059] The tensile properties of glass fiber composite polyetheretherketone (PEEK) filaments and PEEK filaments prepared from chopped glass fibers and chopped montmorillonite glass fibers with different graphene thicknesses (i.e., chopped montmorillonite glass fibers corresponding to different resistivity values) were tested. The results are as follows: Figure 2 As shown. By Figure 2 It is known that graphene with a thickness of nanometer to submicron does not significantly affect the mechanical properties of chopped glass fibers (SGF), and the mechanical properties of the prepared filaments remain very consistent.

[0060] (4) Preparation of gradient filaments The different mixed powders (equal in mass) obtained in step 2 are sequentially and continuously added to the feed barrel of a twin-screw extruder to obtain gradient polyetheretherketone (PEEK) glass fiber composite filaments (for example, by sequentially adding mixed powders containing SGF-10, SGF-100, SGF-400, SGF-600, and SGF-1000, the resulting gradient filaments are named SGF-10-100-400-600-1000 / PEEK). After passing through a blower cooling device and a diameter gauge, the filaments are connected and collected in a traction winding device. By adjusting the traction speed of the traction machine, the diameter of the filaments is controlled within the range of 1.75~1.85 mm.

[0061] Example 2: Preparation of gradient dielectric materials using single-component filaments prepared in Example 1 based on 3D printing technology. A model is constructed using computer modeling software and input into a 3D printer. A filament (a single-component polyetheretherketone (PEEK) composite filament made of montmorillonite glass fiber) obtained in step 3 of Example 1 is uniformly printed to a certain thickness through the 3D printer nozzle. Printing is paused, and a different filament is used before printing continues. The filament can be changed according to the required dielectric constant distribution until printing is complete, resulting in a gradient dielectric material. Specifically, SGF-10 / PEEK, SGF-100 / PEEK, SGF-400 / PEEK, SGF-600 / PEEK, and SGF-1000 / PEEK filaments are changed sequentially, with each filament printed to the same thickness. This allows the 3D printer to print a gradient dielectric material of the desired shape, such as a square gradient dielectric material.

[0062] Figure 1 Image (f) shows a scanning electron microscope (SEM) image of a cross-section of the material. The 3D printing temperature was 430°C. o C, the minimum printhead layer thickness is 0.2 mm, the printing speed is 1-8 mm / s, and the fill rate is 100%.

[0063] The spatial distribution of the dielectric constant of the square gradient dielectric material obtained above was tested, and the results are as follows: Figure 3 As shown in Figure (a), the real part of the dielectric constant of the material can be adjusted within the range of 2-15 depending on the height.

[0064] The dielectric constant versus frequency curves obtained by testing five layers of the square gradient dielectric material described above are shown below. Figure 3 As shown in Figure (b), the dielectric constant of the five layers gradually increases, confirming the successful fabrication of this gradient dielectric material.

[0065] The square gradient dielectric material was cut into 5 layers, and each layer was processed into a tensile specimen. The tensile strength of the tensile specimens was then tested, and the spatial distribution results are as follows: Figure 3 As shown in (c), the tensile strength of each layer of tensile specimens obtained from the material remains basically consistent, indicating uniform distribution and good mechanical stability.

[0066] Example 3: Preparation of gradient dielectric materials using gradient filaments prepared in Example 1 based on 3D printing technology. A model is constructed using computer modeling software and then input into a 3D printer. A gradient dielectric material can also be obtained by continuously printing a gradient filament (SGF-10-100-400-600-1000 / PEEK) obtained in step 4 of Example 1 through the 3D printer until the end.

[0067] The mechanical properties, spatial uniformity, and dielectric constant gradient distribution of the prepared gradient dielectric material are the same as those of the gradient dielectric material prepared in Example 2.

[0068] Comparative Example 1: Preparation of single-component filaments using a mixture of graphene and chopped glass fibers 1) Preparation of mixtures of graphene and chopped glass fibers in different proportions The glass fiber fabric (the same glass fiber fabric as the one in Example 1) was cut into small pieces and then thoroughly pulverized by an ultracentrifugal grinder. The resulting fibers were then sieved through sieves with pore sizes of 200 μm and 100 μm to obtain short glass fibers with a length of 100~200 μm.

[0069] The mass content of graphene in SGF-10 in Example 1 was converted to obtain a "mixture of graphene and chopped glass fiber" with the same mass content of graphene, i.e., a graphene mixture.

[0070] 2) The above graphene mixture was mixed with polyetheretherketone (Jilin Zhongyan Polymer Materials Co., Ltd., product model: 550PF, specification: granular powder with a diameter of about 50μm) in a rotary mixer at a mass ratio of 3:7 for 12 hours. The resulting homogeneous mixture was then placed in an oven and dried at 120°C. o Place at C temperature for 4 hours to dry out the moisture.

[0071] 3) Add the mixed powder obtained in step 2 into the feed barrel of the twin-screw extruder, and set the operating temperature of the extruder heating chamber to 380°C. o C. By controlling the feed rate at 12 g / min and the screw speed at 10 g / min, a single-component graphene-glass fiber composite polyetheretherketone filament was obtained, named SGF-a / PEEK (corresponding to the graphene content in SGF-10). The filaments were then connected and collected in a traction winding device after passing through a blower cooling device and a diameter gauge. By adjusting the traction speed of the traction machine, the diameter of the filaments was controlled within the range of 1.75-1.85 mm.

[0072] Figure 4 The image shown is a cross-sectional SEM image of the SGF-a / PEEK filament, which reveals nearly circular pits formed by chopped glass fibers and irregular sheet-shaped pits formed by graphene.

[0073] Further comparison of SEM images and EDS elemental distribution mapping diagrams of SGF-a / PEEK filament and SGF-10 / PEEK filament, such as... Figure 5As shown in the SEM images, compared to SGF-10 / PEEK, the filler dispersion of SGF-a / PEEK is more uneven, and the graphene nanosheets exhibit significant agglomeration. EDS elemental analysis also indicates that adding graphene separately from chopped glass fibers more easily leads to carbon agglomeration, i.e., graphene nanosheet agglomeration. Therefore, the composite strategy proposed in this patent, utilizing fibers (such as glass fibers) as a rigid carrier, successfully suppresses the agglomeration of graphene in the polymer matrix, establishing an ordered dielectric network structure and providing a new approach to graphene dispersion technology.

[0074] The results above demonstrate that this invention, based on the control of graphene layer thickness using short-cut montmorillonite glass fibers, and through spatial programming stacking via melt extrusion and 3D printing, can produce functional dielectric materials possessing mechanical properties, spatial uniformity, and a gradient distribution of dielectric constant without altering the filler ratio. This dielectric material overcomes the technical barriers inherent in existing solutions that contradict structural stability and tunable dielectric function, and exhibits significant application potential in optimizing non-uniform electric fields.

[0075] The present invention has been described in detail above. For those skilled in the art, the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope, and without requiring unnecessary experiments. Although specific embodiments have been given, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including changes made using conventional techniques known in the art that depart from the scope disclosed herein. Some of the essential features can be applied within the scope of the following appended claims.

Claims

1. A composition for 3D printing, comprising short-cut Mxene fibers and a thermoplastic resin; The mass ratio of the short-cut Mxene fibers and the thermoplastic resin is 1: (1-10) ; The short-cut Mxene fibers are obtained by cutting Mxene fibers or Mxene fiber fabric, and the length of the short-cut Mxene fibers is 100-200 μm; The shorted monelene fibers include: The fiber and a graphene layer formed on the surface of the fiber.

2. The composition of claim 1, wherein: The fiber is selected from at least one of the following: glass fiber, alumina fiber, boron nitride fiber.

3. The composition according to claim 1 or 2, characterized in that: The thickness of the graphene layer in the Mxene fibers or Mxene fiber fabric is 0.335-16.75 nm, or the number of layers of the graphene layer ranges from 1 to 50 layers; and / or the surface resistance of the Montemayor fabric is 10-1000 Ω sq -1 .

4. The composition according to claim 1 or 2, characterized in that: The thermoplastic resin is selected from at least one of the following: polyether ether ketone, nylon, ABS, TPU. 5.A method for manufacturing a filament using the composition of any one of claims 1-4, comprising the following steps: obtaining a single-component filament or a gradient filament from the composition by using an extrusion molding method.

6. The method of claim 5, wherein: The extrusion molding is melt extrusion molding; The melt extrusion molding is carried out in a twin-screw extruder, and the working temperature of the heating cavity of the extruder is set to 350-400 o C, the feeding speed is controlled to be 8-20 g / min, and the screw rotation speed is 8-20 g / min.

7. The method of claim 6, wherein: The gradient filament is prepared by the following method: the composition of any one of claims 1-4, which is composed of short-cut Mxene fibers with different graphene layer thicknesses, is added into the feeding cylinder of a double-screw extruder in batches without interruption in the order of decreasing or increasing graphene layer thickness, to obtain a gradient filament.

8. The method according to any one of claims 5-7, characterized by: The method further comprises the following steps: connecting and collecting the obtained single-component filament or gradient filament in a traction winding device after passing through a blast cooling device and a diameter measuring instrument, and controlling the diameter of the filament to be within the range of 1.75-1.85 mm by adjusting the traction speed of the traction machine. 9.A single-component filament or a gradient filament prepared by the method of any one of claims 5-8. 10.A method for preparing a gradient dielectric material by 3D printing, comprising the following steps: using the single-component filament of claim 9, which is prepared from short-cut Mxene fibers with different graphene layers, to obtain a desired gradient dielectric material by controlling the 3D printing process.

11. The method of claim 10, wherein: The control of the 3D printing process is as follows: a single-component filament is uniformly printed to a certain thickness through the nozzle of a 3D printer, printing is paused, another single-component filament is replaced, and printing is continued, the filaments are replaced according to the gradient dielectric constant distribution requirement until the printing is completed, and a desired gradient dielectric material is obtained; The replacement order of the single-component filaments is according to the gradient dielectric constant distribution requirement, and the single-component filaments are replaced in the order of decreasing or increasing graphene layer thickness in the short-cut Mxene fibers in the single-component filaments. 12.A method for preparing a gradient dielectric material by 3D printing, comprising the following steps: using the gradient filament of claim 9 to obtain a desired gradient dielectric material by using a 3D printing process. 13.A gradient dielectric material prepared by the method of any one of claims 10-12.

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