An isotropic photocurable material and a method for preparing the same

Abstract

The application discloses an isotropic photocuring material and a preparation method thereof. The preparation method specifically comprises the following steps: (1) performing surface treatment on carbon fibers by using a chemical grafting modification method to obtain 4-vinylaniline modified carbon fibers; and (2) mixing epoxy acrylate, dicyclopentadiene acrylate and a photoinitiator, adding the 4-vinylaniline modified carbon fibers as a reinforcing phase, and obtaining the isotropic photocuring material by photocuring 3D printing. The application uses the chemical grafting modification method to perform surface treatment on the fibers to obtain the 4-vinylaniline modified carbon fibers, so that a chemical bond exists between the modified fibers and the matrix, the interface bonding degree is higher, the tensile strength of a printed product is further improved, and anisotropy is further reduced. The application utilizes the bonding between the modified carbon fibers and the resin matrix to realize isotropy while enhancing the mechanical properties of the material, and is expected to expand the practical application scenarios of the photocuring 3D printed product in the industry.

Description

Technical Field

[0001] This invention relates to an isotropic photocurable material and its preparation method, specifically to a photosensitive acrylate resin system reinforced by modifying carbon fiber with 4-ethylene aniline, belonging to the field of chemical and polymer materials technology. Background Technology

[0002] Photopolymer 3D printing is a technology that uses computer-controlled visible / ultraviolet light to initiate the polymerization of liquid photosensitive resin at specific locations on a printing platform, creating three-dimensional structures layer by layer. Depending on the control system, photopolymer 3D printing technologies include stereolithography (SLA), digital light processing (DLP), liquid crystal display (LCD), continuous liquid interface fabrication (CLIP), and high-area rapid printing (HARP). These printing technologies offer advantages such as high printing speed, high resolution, easy separation of the printed structure from the liquid resin, and reusability of the uncured resin.

[0003] However, the most commonly used photopolymer 3D printing acrylic resins currently have poor mechanical properties, limiting their practical application in fields such as medical devices, electronic components, automotive parts, and aerospace. This is due, in part, to the inherent structure of acrylic resins; and in part, to the layer-by-layer deposition modeling of photopolymer 3D printing, resulting in weak interlayer forces. This leads to anisotropic mechanical properties in the printed samples, particularly with significantly lower mechanical properties perpendicular to the printing direction compared to other directions.

[0004] Improving the mechanical properties of photopolymer 3D printing resins to meet broader application needs has become a current research hotspot. Summary of the Invention

[0005] Purpose of the invention: To address the shortcomings of existing technologies, this invention provides an isotropic photocurable material and its preparation method. A chemical grafting modification method is used to treat the surface of fibers to obtain 4-ethylene aniline modified carbon fibers. This results in chemical bonds between the modified fibers and the matrix, leading to a higher degree of interfacial bonding, further improving the tensile strength of the printed product, and further reducing anisotropy.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A first aspect of the present invention is to provide an isotropic photocurable material, wherein the isotropic photocurable material is a photosensitive resin in which 4-ethyleneaniline modified carbon fibers are distributed, the content of the 4-ethyleneaniline modified carbon fibers is 1-3 wt.% of the photosensitive resin, the 4-ethyleneaniline modified carbon fibers are 4-ethyleneaniline grafted onto the surface of the carbon fibers, wherein the tensile strength anisotropy of the isotropic photocurable material is less than 11.0%, and the elongation at break anisotropy is less than 8.5%.

[0008] A second aspect of the present invention is to provide the use of 4-ethylene aniline modified carbon fiber in the preparation of an isotropic photocurable material, the isotropic photocurable material being as described above, wherein the 4-ethylene aniline modified carbon fiber is formed by grafting 4-ethylene aniline onto the surface of carbon fiber.

[0009] The third aspect of this invention is to provide a method for preparing an isotropic photocurable material, the method comprising the following steps:

[0010] (1) Using 4-ethyleneaniline as raw material, 4-ethyleneaniline modified carbon fiber was obtained by surface treatment of carbon fiber using chemical grafting modification method.

[0011] (2) Epoxy acrylate, dicyclopentadiene acrylate, and a photoinitiator are mixed to obtain a photosensitive resin. 4-vinylaniline-modified carbon fiber is added as a reinforcing phase, wherein the content of the 4-vinylaniline-modified carbon fiber is [amount missing]% of the photosensitive resin. 1- 3wt.% The material is uniformly dispersed and then isotropically photocurable material is obtained through photocuring 3D printing.

[0012] A fourth aspect of the invention is to provide the application of isotropic photocurable materials prepared as described above, or as any of the methods described above, in the fields of medical devices, electronic components, automotive parts, or aerospace.

[0013] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0014] 1. Carbon fiber (CF) is a novel high-strength, high-modulus fiber with a carbon content of over 95%. When added as a reinforcing phase to a photosensitive resin matrix, it significantly improves mechanical properties. Based on this, this invention uses a chemical grafting modification method to surface-treat the fiber to obtain 4-ethyleneaniline-modified carbon fiber. This results in chemical bonds between the modified fiber and the matrix, leading to a higher degree of interfacial bonding, further improving the tensile strength of the printed product and reducing anisotropy. This invention utilizes the bonding effect between the modified carbon fiber and the resin matrix to achieve isotropy while enhancing the material's mechanical properties, potentially expanding the practical industrial applications of photopolymer 3D printed products.

[0015] 2. This invention provides a novel CF-reinforced photosensitive acrylate resin system for photopolymer DLP 3D printing. 4-ethyleneaniline-modified carbon fibers can act as interlayer bonding agents, potentially compensating for the weak interfacial bonding caused by the layer-by-layer manufacturing process. This method is simple to operate and significantly eliminates the anisotropy of photosensitive acrylates. Attached Figure Description

[0016] Figure 1This is a schematic diagram illustrating the reasons for the anisotropy of mechanical properties in photopolymer 3D printed parts.

[0017] Figure 2 This is a schematic diagram illustrating the principle of the present invention.

[0018] Figure 3 This is the viscosity curve of the printing solution with different CF addition amounts provided in Experimental Example 1 of this invention.

[0019] Figure 4 This is the relationship between curing depth and ultraviolet exposure energy provided in Experimental Example 1 of this invention.

[0020] Figure 5 It is the 4-ethyleneaniline structure provided in Example 1 of this invention.

[0021] Figure 6 This is a 3D printing process diagram of the modified CF-reinforced sample provided in Embodiment 1 of the present invention.

[0022] Figure 7 These are the XPS wide-scan spectra of CF before and after modification provided in Embodiment 1 of the present invention.

[0023] Figure 8 It is the N1s peak of CF-Enamine provided in Embodiment 1 of the present invention.

[0024] Figure 9 It is the C1s peak of CF provided in Experimental Example 1 of this invention.

[0025] Figure 10 It is the C1s peak of CF-Enamine provided in Embodiment 1 of the present invention.

[0026] Figure 11 The tensile properties of the modified CF composite material provided in Example 1 of this invention are anisotropic.

[0027] Figure 12 This is the tensile fracture section of the modified CF-reinforced sample printed in the horizontal direction according to Embodiment 1 of the present invention.

[0028] Figure 13 This is the tensile fracture section of the modified CF-reinforced sample printed in the vertical direction according to Embodiment 1 of the present invention.

[0029] Figure 14 This is the 3D printing lattice model provided in Embodiment 1 of the present invention.

[0030] Figure 15 This is the 3D printed wrench model provided in Embodiment 1 of the present invention. Detailed Implementation

[0031] In the DLP 3D printing process, because each layer of photosensitive resin is cured and then the next layer is added, the bonding strength between layers is limited. This insufficient interlayer bonding strength causes the printed parts to exhibit extremely obvious anisotropy in terms of mechanical properties, such as... Figure 1 As shown, this anisotropy can exacerbate stress concentration when the part is subjected to complex stresses, thus adversely affecting the overall performance of the part.

[0032] Current methods for addressing the anisotropy of mechanical properties in photopolymer 3D printed products mainly include core-shell particle toughening, constructing dual-curing networks, and introducing dynamic covalent bonds. These approaches all aim to strengthen the bonding between layers. However, the addition of core-shell particles cannot eliminate the anisotropy of elongation at break; photothermal dual-curing systems require additional heat treatment; and the introduction of dynamic disulfide bonds requires the design and synthesis of special structures, resulting in lower tensile strength values.

[0033] Based on this situation, the present invention provides a novel CF-reinforced photosensitive acrylate resin system that can be used for photopolymerizable DLP 3D printing. For example... Figure 2 As shown, this invention uses a chemical grafting modification method to treat the surface of fibers to obtain 4-ethylene aniline modified carbon fibers, which results in chemical bonds between the modified fibers and the matrix, and a higher degree of interfacial bonding. The 4-ethylene aniline modified carbon fibers can play an overlapping role between layers, which is expected to make up for the weak interfacial bonding caused by the layer-by-layer manufacturing method, thereby further improving the tensile strength of the printed products and further reducing anisotropy.

[0034] This invention has the following advantages:

[0035] On the one hand, this invention utilizes the bonding effect between modified carbon fiber and resin matrix to achieve isotropy while enhancing the mechanical properties of the material, which is expected to expand the practical application scenarios of photopolymer 3D printed products in industry.

[0036] On the other hand, this method is simple to operate and has a significant effect on eliminating the anisotropy of photosensitive acrylates.

[0037] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments. However, this should not be construed as limiting the scope of the present invention to the following examples. Various substitutions or modifications made based on ordinary technical knowledge and conventional methods in the art without departing from the above-described methodological concept of the present invention should be included within the scope of the present invention.

[0038] Example

[0039] A first aspect of the present invention is to provide an isotropic photocurable material, wherein the isotropic photocurable material is a photosensitive resin in which 4-ethyleneaniline modified carbon fibers are distributed, the content of the 4-ethyleneaniline modified carbon fibers is 1-3 wt.% of the photosensitive resin, the 4-ethyleneaniline modified carbon fibers are 4-ethyleneaniline grafted onto the surface of the carbon fibers, wherein the tensile strength anisotropy of the isotropic photocurable material is less than 11.0%, and the elongation at break anisotropy is less than 8.5%.

[0040] Furthermore, the content of the 4-ethyleneaniline modified carbon fiber is 2-3 wt.% of the photosensitive resin. Even more specifically, the content of the 4-ethyleneaniline modified carbon fiber is 3 wt.% of the photosensitive resin.

[0041] Furthermore, the tensile strength anisotropy of the isotropic photocurable material is less than 8.0%, and the elongation at break anisotropy is less than 6.0%. More preferably, the tensile strength anisotropy of the isotropic photocurable material is less than 4.0%, and the elongation at break anisotropy is less than 2.5%.

[0042] Furthermore, the tensile strength of the isotropic photocurable material is higher than 60 MPa.

[0043] Furthermore, the elongation at break of the isotropic photocurable material is higher than 5%.

[0044] Furthermore, the isotropic photocurable material has C1s peaks of C=C, CC, N=CO and O=CO at 284.7 eV, 285.8 eV, 287.0 eV and 289.2 eV, respectively.

[0045] A second aspect of the present invention is to provide the use of 4-ethylene aniline modified carbon fiber in the preparation of an isotropic photocurable material, the isotropic photocurable material being as described above, wherein the 4-ethylene aniline modified carbon fiber is formed by grafting 4-ethylene aniline onto the surface of carbon fiber.

[0046] The third aspect of this invention is to provide a method for preparing an isotropic photocurable material, the method comprising the following steps:

[0047] (1) Using 4-ethyleneaniline as raw material, 4-ethyleneaniline modified carbon fiber was obtained by surface treatment of carbon fiber using chemical grafting modification method.

[0048] (2) Epoxy acrylate, dicyclopentadiene acrylate and photoinitiator are mixed to obtain photosensitive resin. 4-ethylene aniline modified carbon fiber is added as a reinforcing phase. The content of 4-ethylene aniline modified carbon fiber is 1-3 wt.% of the photosensitive resin. The carbon fiber is evenly dispersed and is obtained by photocuring 3D printing to obtain an isotropic photocurable material.

[0049] Furthermore, the content of the 4-ethyleneaniline modified carbon fiber is 2-3 wt.% of the photosensitive resin. Even more specifically, the content of the 4-ethyleneaniline modified carbon fiber is 3 wt.% of the photosensitive resin.

[0050] Furthermore, in step (2), the monofunctional acrylate monomer includes one or more of isobornyl acrylate, dicyclopentadiene acrylate, hydroxyethyl acrylate, diethoxy acrylate, and tetrahydrofuran acrylate.

[0051] Further, in step (2), the photoinitiator includes one or more of 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoyl-ethoxy-phenylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; and / or

[0052] Furthermore, in step (2), the mass ratio of the bisphenol A epoxy acrylate, the monofunctional acrylate monomer, and the photoinitiator is 20-36:4-20:0.4-1.2.

[0053] Furthermore, the dispersion time is 1 to 5 minutes.

[0054] Furthermore, the photopolymer 3D printing process is followed by post-curing, and the post-curing time is 10-50 seconds.

[0055] Furthermore, the specific method of step (1) includes:

[0056] (i) Carbon fiber CF is added to an acidic oxidizing agent to carry out an oxidation reaction, washed with water and dried to obtain oxidized carbon fiber OCF;

[0057] (ii) Add OCF and catalyst to one of the following solutions of 4-ethyleneaniline: ethanol, isopropanol, and N,N-dimethylformamide, and carry out an amidation reaction under a nitrogen atmosphere;

[0058] (iii) After the reaction was complete, the carbon fiber was washed with N,N-dimethylformamide and dried to obtain 4-ethylene aniline modified carbon fiber CF-Enamine.

[0059] Furthermore, in step (i), the acidic oxidant is one or more strong acids, including concentrated sulfuric acid, nitric acid, or hydrochloric acid.

[0060] Furthermore, in step (i), the amount of acidic oxidant added is 50-200 ml, based on 2 g equivalent carbon fiber.

[0061] Furthermore, in step (i), the oxidation reaction is carried out at a temperature of 50–100°C for 2–10 hours.

[0062] Furthermore, in step (i), the drying includes vacuum drying at 50–120°C for 6–12 hours.

[0063] Furthermore, in step (ii), the mass ratio of OCF to 4-vinylaniline is 0.5 to 3:1. Preferably, it is 0.6 to 2.4:1.

[0064] Furthermore, in step (ii), the catalyst for the amidation reaction includes one or more of dicyclohexylcarbodiimide, 2-(7-azabenzotriazole)-N,N,N',N'-tetramethylurea hexafluorophosphate, and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide.

[0065] Furthermore, in step (ii), the molar ratio of the catalyst to 4-ethyleneaniline is 1:2.0 to 3.0.

[0066] Furthermore, in step (ii), the amidation reaction is carried out at a temperature of 100–150°C for 2–10 h.

[0067] Furthermore, in step (ii), the drying includes vacuum drying at 50–120°C for 6–12 hours.

[0068] A fourth aspect of the invention is to provide the application of isotropic photocurable materials prepared as described above, or as any of the methods described above, in the fields of medical devices, electronic components, automotive parts, or aerospace.

[0069] The present invention will be further described below with reference to the accompanying drawings and embodiments. The present invention can be better understood from the following embodiments. However, those skilled in the art will readily understand that the specific material ratios, process conditions, and results described in the embodiments are for illustrative purposes only and should not, and will not, limit the present invention as described in detail in the claims.

[0070] Example 1: Preparation of Unmodified CF-Reinforced Photocurable Composite Material

[0071] To explore the process conditions for the preparation of modified CF materials for photocurable composites, this invention first uses CF as a raw material and studies the effect of different CF addition amounts on the preparation of CF-reinforced photocurable composites. This aims to serve as a control for the preparation of modified CF-reinforced photocurable composites using modified CF materials, and also to provide some reference for the process conditions of using modified CF materials for the preparation of modified CF-reinforced photocurable composites.

[0072] The specific preparation method of the CF-reinforced photocurable composite material in this experimental example is as follows:

[0073] Bisphenol A epoxy acrylate (24g), dicyclopentadiene acrylate (16g), and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (0.8g) were mixed to obtain a photosensitive resin.

[0074] Then, different amounts of CF (0, 0.4, 0.8, 1.2, 1.6, and 2.0 g, corresponding to 0 wt.%, 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, and 5 wt.%) were added to the photosensitive resin and dispersed at 3000 r / min for 3 min using a high-speed disperser to obtain a uniformly mixed CF-reinforced photosensitive resin solution. After removing air bubbles, the solution was poured into a commercial 405nm DLP 3D printer to prepare CF composite materials.

[0075] After printing, use ethanol to clean the residual resin solution on the sample surface, and then use a full-band tracked light curing machine for post-curing, with a total curing time of about 30 seconds.

[0076] See appendix Figure 3 This is the viscosity curve of the printing solution with different CF addition amounts provided in Experimental Example 1 of this invention. As can be seen from the figure, when the CF addition amount is 5wt% and the shear rate is 1s, the viscosity curve is significantly higher. -1 At the specified viscosity, the resin system reached 24.2 Pa·s, making printing difficult. However, the printing solution with a viscosity of 0-4 wt% had a maximum viscosity of 5.5 Pa·s, both meeting the requirements for DLP 3D printing. Therefore, based on these test results, a 0-4 wt% addition amount was used in subsequent performance tests of the CF-reinforced photopolymer composite material in this experimental example.

[0077] See appendix Figure 4 This is the relationship between curing depth and UV exposure energy provided in Experimental Example 1 of this invention. As shown in the figure, the transmission depth (Dp) and the critical UV exposure energy (Ec), i.e., the minimum energy required to begin curing, can be obtained by fitting the logarithm of the curing depth (Cd) of the printing solution to the UV exposure energy E according to the Jacob equation:

[0078]

[0079] The higher the CF content, the lower the curing depth (Cd) of the composite material.

[0080] See appendix Figure 5 It is the 4-ethyleneaniline structure provided in Example 1 of this invention.

[0081] See Table 1, which shows the transmission depth and critical ultraviolet exposure energy provided in Example 1 of this invention. As the CF content increases, the Dp and Ec values ​​show a decreasing trend, indicating that the curing layer starts to form earlier.

[0082] Table 1. Penetration Depth and Critical Ultraviolet Exposure Energy

[0083]

[0084] Referring to Table 2, which shows the tensile properties of the initial CF composite material provided in Experimental Example 1 of this invention, the highest tensile strength (59.7 MPa) was observed when the photosensitive resin contained 3 wt% CF. This represents a 30.8% increase compared to the sample prepared from pure resin (containing 0 wt% CF). Furthermore, the tensile strength did not increase with increasing CF content in the resin; it peaked at 3 wt% and then decreased with further increases in CF content. This invention aims to prepare an isotropic photocurable material with good mechanical properties. Since the composite material exhibits the highest tensile strength with the addition of 3 wt% CF, subsequent examples controlled the CF addition within the range of 0-3 wt% during the preparation of the modified CF-reinforced photocurable composite material, exploring the influencing factors of anisotropy while ensuring good mechanical properties.

[0085] Table 2 Tensile properties of the initial CF composite material

[0086]

[0087] Example 1: Preparation of modified CF-reinforced photocurable composite material

[0088] The embodiments of the present invention refer to the process conditions of Experimental Example 1 above, and use modified CF as raw material to prepare modified CF reinforced photocurable composite material.

[0089] The specific preparation method of the modified CF-reinforced photocurable composite material in this embodiment is as follows:

[0090] 1) Preparation of 4-vinylaniline modified carbon fiber CF-Enamine-1

[0091] 2g of carbon fiber (CF) was placed in a flask and 120ml of nitric acid solution was added. The mixture was stirred at 80℃ for 4h. After the reaction was complete, the fiber was washed with deionized water and then dried in an oven at 80℃ for 12h to obtain oxidized carbon fiber (OCF).

[0092] OCF (1.2 g) and catalyst 2-(7-azabenzotriazole)-N,N,N',N'-tetramethylurea hexafluorophosphate (2.4 g, 6.3 mmol) were added to 60 ml of N,N-dimethylformamide solution containing 4-vinylaniline (1 g, 7.4 mmol) and reacted at 120 °C under a nitrogen atmosphere for 6 h.

[0093] The fibers were then washed with N,N-dimethylformamide and dried in a vacuum oven at 80°C for 12 hours to obtain 4-ethylene aniline modified carbon fibers (denoted as CF-Enamine-1).

[0094] 2) Preparation of CF-Enamine-1 reinforced photocurable composite material

[0095] Bisphenol A epoxy acrylate (24g), dicyclopentadiene acrylate (16g), and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (0.8g) were mixed to obtain a photosensitive resin.

[0096] Then, 1.2g of CF-Enamine-1 was added to the photosensitive resin, corresponding to 3wt.% of CF-Enamine-1. The mixture was dispersed at 3000r / min for 3min using a high-speed disperser to obtain a uniformly mixed CF-Enamine-1 reinforced photosensitive resin solution. After removing air bubbles, the solution was poured into a commercial 405nm DLP 3D printer to prepare CF-Enamine-1 reinforced photocurable composite material.

[0097] After printing, use ethanol to clean the residual resin solution on the sample surface, and then use a full-band tracked light curing machine for post-curing, with a total curing time of about 30 seconds.

[0098] See appendix Figure 5 It is the 4-ethyleneaniline structure provided in Example 1 of this invention.

[0099] See appendix Figure 6 This is a 3D printing process diagram of the modified CF reinforced sample provided in Example 1 of the present invention. The modified CF reinforced composite material was prepared by DLP 3D printing with 4-ethylene aniline modified CF as the reinforcement and epoxy acrylate and dicyclopentadiene acrylate as the matrix.

[0100] See appendix Figure 7 It is the XPS wide scan spectrum of CF before and after modification provided in Experimental Example 1 and Example 1 of this invention. The signal peaks of C, N and O of CF-Enamine-1 are located near 284.8, 400.1 and 532.9 eV, respectively. Compared with CF, the N content on the surface of CF-Enamine-1 fiber is significantly increased.

[0101] See appendix Figure 8 It is the N1s peak of CF-Enamine-1 provided in Embodiment 1 of the present invention, which has a single peak at 400.2 eV, corresponding to N=CO.

[0102] See appendix Figure 9 It is the C1s peak of CF provided in Experimental Example 1 of this invention. The C1s spectrum of untreated CF can be divided into four peaks: 284.7 eV, 285.7 eV, 286.6 eV and 289.1 eV, which correspond to C=C, CC, CO and O=CO, respectively. This indicates that fiber fragments or contaminants may adhere to the CF surface during cutting and storage, making the fiber surface not completely inert, but containing some functional groups.

[0103] See appendix Figure 10 This is the C1s peak of CF-Enamine-1 provided in Embodiment 1 of the present invention. The C1s peak of CF-Enamine-1 can be divided into the following four peaks: C=C, CC, N=CO, and O=CO, located at 284.7 eV, 285.8 eV, 287.0 eV, and 289.2 eV, respectively. The structure is similar to... Figure 5 Correspondingly, the appearance of N=CO is due to the condensation reaction between the carboxyl group on CF and the amino group of 4-ethyleneaniline under the action of 2-(7-azabenzotriazole)-N,N,N',N'-tetramethylurea hexafluorophosphate.

[0104] See Table 3, which shows the tensile properties of the modified CF composite material provided in Example 1 of this invention in different directions. When 3 wt% CF-Enamine-1 is added, the tensile strength of the printed sample reaches 66.0 MPa, which is 44.7% higher than that of the resin sample and 10.6% higher than that of the CF-reinforced composite material in Example 1.

[0105] Table 3 Tensile properties of modified CF-Enamine composites in different directions

[0106]

[0107] See appendix Figure 11 It is the anisotropy of the tensile properties of the modified CF composite material provided in Example 1 of this invention. The anisotropy of the printing material is calculated according to the following formula:

[0108]

[0109] Compared to the pure resin printed sample (40.6%), the tensile strength anisotropy of the printed sample containing 3 wt% CF in Example 1 decreased significantly to 12.1%, while the elongation at break anisotropy decreased to 8.9%. When the fiber in Example 1 was modified, the tensile strength anisotropy of the reinforced printed sample containing 3 wt% modified CF further decreased to 3.3%, while the elongation at break anisotropy decreased to 1.9%.

[0110] See appendix Figure 12 , 13 These are the tensile fracture sections of the modified CF-reinforced sample printed in the horizontal direction and the modified CF-reinforced sample printed in the vertical direction, respectively, provided in Embodiment 1 of the present invention. CF-Enamine-1 is randomly distributed in the resin as a whole, and some fibers penetrate through different layers, that is, they connect the layers together like nails, which improves the interlayer adhesion and thus improves the mechanical strength in this direction.

[0111] See appendix Figure 14 It is the 3D printed lattice model provided in Embodiment 1 of the present invention.

[0112] See appendix Figure 15 It is the 3D printed wrench model provided in Embodiment 1 of the present invention.

[0113] Example 2: Preparation of modified CF-reinforced photocurable composite material

[0114] The specific preparation method of the modified CF-reinforced photocurable composite material in this embodiment is as follows:

[0115] 1) Preparation of 4-vinylaniline modified carbon fiber CF-Enamine-2

[0116] 2g of carbon fiber was placed in a flask and 120ml of hydrochloric acid solution was added. The mixture was stirred at 90℃ for 8 hours. After the reaction was complete, the fiber was washed with deionized water and then dried in an oven at 100℃ for 12 hours to obtain oxidized carbon fiber (OCF).

[0117] OCF (2 g) and catalyst 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (1.21 g, 6.3 mmol) were added to 60 ml of N,N-dimethylformamide solution containing 4-vinylaniline (3 g, 22.2 mmol) and reacted at 100 °C under a nitrogen atmosphere for 8 h.

[0118] The fibers were then washed with N,N-dimethylformamide and dried in a vacuum oven at 100°C for 12 hours to obtain 4-ethylene aniline modified carbon fibers (denoted as CF-Enamine-2).

[0119] 2) Preparation of CF-Enamine-2 reinforced photocurable composite material

[0120] Bisphenol A epoxy acrylate (20g), hydroxyethyl acrylate (20g), and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (0.4g) were mixed to obtain a photosensitive resin.

[0121] Then, 0.4 g of CF-Enamine-2 was added to the photosensitive resin (corresponding to an addition amount of 1 wt.%), and dispersed at 3000 r / min for 3 min using a high-speed disperser to obtain a uniformly mixed CF-Enamine-2 reinforced photosensitive resin solution. After removing air bubbles, the solution was poured into a commercial 405nm DLP 3D printer to prepare CF-Enamine-2 reinforced photocurable composite material.

[0122] After printing, use ethanol to clean the residual resin solution on the sample surface, and then use a full-band tracked light curing machine for post-curing, with a total curing time of about 30 seconds.

[0123] The tensile strength anisotropy of the GF-Enamine-2 reinforced photocurable composite material sample prepared in this embodiment is 10.7%, and the elongation at break anisotropy is 8.1%.

[0124] Example 3: Preparation of modified CF-reinforced photocurable composite material

[0125] The specific preparation method of the modified CF-reinforced photocurable composite material in this embodiment is as follows:

[0126] 1) Preparation of 4-vinylaniline modified carbon fiber CF-Enamine-3

[0127] 2g of carbon fiber was placed in a flask and 60ml of nitric acid solution was added. The mixture was stirred at 80℃ for 10h. After the reaction was complete, the fiber was washed with deionized water and then dried in an oven at 50℃ for 12h to obtain oxidized carbon fiber (OCF).

[0128] OCF (2 g) and catalyst 2-(7-azabenzotriazole)-N,N,N',N'-tetramethylurea hexafluorophosphate (2.4 g, 6.3 mmol) were added to 60 ml of N,N-dimethylformamide solution containing 4-vinylaniline (2 g, 14.8 mmol) and reacted at 100 °C under a nitrogen atmosphere for 10 h.

[0129] The fibers were then washed with N,N-dimethylformamide and dried in a vacuum oven at 50°C for 12 hours to obtain 4-ethylene aniline modified carbon fiber (CF-Enamine-3).

[0130] 2) Preparation of CF-Enamine-3 reinforced photocurable composite material

[0131] Bisphenol A epoxy acrylate (32g), bisethoxy acrylate (8g) and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (0.8g) were mixed to obtain a photosensitive resin.

[0132] Then, 0.8g of CF-Enamine-3 was added to the photosensitive resin (corresponding to an addition amount of 2wt.%), and dispersed at 3000r / min for 3min using a high-speed disperser to obtain a uniformly mixed CF-Enamine-3-reinforced photosensitive resin solution. After removing air bubbles, the solution was poured into a commercial 405nm DLP 3D printer to prepare CF-Enamine-3-reinforced photocurable composite material.

[0133] After printing, use ethanol to clean the residual resin solution on the sample surface, and then use a full-band tracked light curing machine for post-curing, with a total curing time of about 50 seconds.

[0134] The tensile strength anisotropy of the GF-Enamine-3 reinforced photocurable composite material sample prepared in this embodiment is 7.3%, and the elongation at break anisotropy is 4.9%.

[0135] Example 4: Preparation of modified CF-reinforced photocurable composite material

[0136] The specific preparation method of the modified CF-reinforced photocurable composite material in this embodiment is as follows:

[0137] 1) Preparation of CF-Enamine-4 modified CF carbon fiber with 4-vinylaniline

[0138] 2g of initial carbon fiber was placed in a flask and 60ml of hydrochloric acid solution was added. The mixture was stirred at 100℃ for 2h. After the reaction was complete, the fiber was washed with deionized water and then dried in an oven at 60℃ for 12h to obtain oxidized carbon fiber (OCF).

[0139] OCF (1.2 g) and catalyst 2-(7-azabenzotriazole)-N,N,N',N'-tetramethylurea hexafluorophosphate (2.4 g, 6.3 mmol) were added to 60 ml of N,N-dimethylformamide solution containing 4-vinylaniline (1 g, 7.4 mmol) and reacted at 140 °C under a nitrogen atmosphere for 10 h.

[0140] The fibers were then washed with N,N-dimethylformamide and dried in a vacuum oven at 60°C for 12 hours to obtain 4-ethylene aniline modified carbon fibers (denoted as CF-Enamine-4).

[0141] 2) Preparation of CF-Enamine-4 reinforced photocurable composite material

[0142] Bisphenol A epoxy acrylate (36g), tetrahydrofuran acrylate (4g) and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (0.4g) were mixed to obtain a photosensitive resin.

[0143] Then, 0.8g of CF-Enamine-4 was added to the photosensitive resin (corresponding to an addition amount of 2wt.%), and dispersed at 3000r / min for 3min using a high-speed disperser to obtain a uniformly mixed CF-Enamine-4-reinforced photosensitive resin solution. After removing air bubbles, the solution was poured into a commercial 405nm DLP 3D printer to prepare a CF-Enamine-4-reinforced photocurable composite material.

[0144] After printing, use ethanol to clean the residual resin solution on the sample surface, and then use a full-band tracked light curing machine for post-curing, with a total curing time of about 30 seconds.

[0145] The tensile strength anisotropy of the GF-Enamine-4 reinforced photocurable composite material sample prepared in this embodiment is 6.6%, and the elongation at break anisotropy is 4.4%.

[0146] Example 5: Preparation of modified CF-reinforced photocurable composite material

[0147] The specific preparation method of the modified CF-reinforced photocurable composite material in this embodiment is as follows:

[0148] 1) Preparation of 4-vinylaniline modified carbon fiber CF-Enamine-5

[0149] 2g of initial carbon fiber was placed in a flask and 180ml of sulfuric acid solution was added. The mixture was stirred at 60℃ for 8h. After the reaction was complete, the fiber was washed with deionized water and then dried in an oven at 70℃ for 12h to obtain oxidized carbon fiber (OCF).

[0150] OCF (1.2 g) and catalyst 2-(7-azabenzotriazole)-N,N,N',N'-tetramethylurea hexafluorophosphate (2.4 g, 6.3 mmol) were added to 60 ml of N,N-dimethylformamide solution containing 4-vinylaniline (0.5 g, 3.7 mmol) and reacted at 120 °C under a nitrogen atmosphere for 8 h.

[0151] The fibers were then washed with N,N-dimethylformamide and dried in a vacuum oven at 70°C for 12 hours to obtain 4-ethylene aniline modified carbon fibers (denoted as CF-Enamine-5).

[0152] 2) Preparation of CF-Enamine-5 reinforced photocurable composite material

[0153] Bisphenol A epoxy acrylate (24g), dicyclopentadiene acrylate (16g) and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (0.4g) were mixed to obtain a photosensitive resin.

[0154] Then, 0.4g of CF-Enamine-5 was added to the photosensitive resin (corresponding to an addition amount of 1wt.%), and dispersed at 3000r / min for 3min using a high-speed disperser to obtain a uniformly mixed CF-Enamine-5 reinforced photosensitive resin solution. After removing air bubbles, the solution was poured into a commercial 405nm DLP 3D printer to prepare CF-Enamine-5 reinforced photocurable composite material.

[0155] After printing, use ethanol to clean the residual resin solution on the sample surface, and then use a full-band tracked light curing machine for post-curing, with a total curing time of about 30 seconds.

[0156] The tensile strength anisotropy of the GF-Enamine-5 reinforced photocurable composite material sample prepared in this embodiment is 10.4%, and the elongation at break anisotropy is 8.1%.

[0157] Example 6: Preparation of modified CF-reinforced photocurable composite material

[0158] The specific preparation method of the modified CF-reinforced photocurable composite material in this embodiment is as follows:

[0159] 1) Preparation of 4-vinylaniline modified carbon fiber CF-Enamine-6

[0160] 2g of initial carbon fiber was placed in a flask and 120ml of nitric acid solution was added. The mixture was stirred at 80℃ for 10h. After the reaction was complete, the fiber was washed with deionized water and then dried in an oven at 120℃ for 12h to obtain oxidized carbon fiber (OCF).

[0161] OCF (1.2 g) and catalyst 2-(7-azabenzotriazole)-N,N,N',N'-tetramethylurea hexafluorophosphate (1.2 g, 3.15 mmol) were added to 60 ml of N,N-dimethylformamide solution containing 4-vinylaniline (2 g, 14.8 mmol) and reacted at 100 °C under a nitrogen atmosphere for 4 h.

[0162] The fibers were then washed with N,N-dimethylformamide and dried in a vacuum oven at 120°C for 12 hours to obtain 4-ethylene aniline modified carbon fibers (denoted as CF-Enamine-6).

[0163] 2) Preparation of CF-Enamine-6 ​​reinforced photocurable composite material

[0164] Bisphenol A epoxy acrylate (28g), isoborneol acrylate (12g), and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (0.8g) were mixed to obtain a photosensitive resin.

[0165] Then, 0.8g of CF-Enamine-6 ​​was added to the photosensitive resin, corresponding to an addition amount of 2wt.%. The mixture was dispersed at 3000r / min for 3min using a high-speed disperser to obtain a uniformly mixed CF-Enamine-6-reinforced photosensitive resin solution. After removing air bubbles, the solution was poured into a commercial 405nm DLP 3D printer to prepare CF-Enamine-6-reinforced photocurable composite material.

[0166] After printing, use ethanol to clean the residual resin solution on the sample surface, and then use a full-band tracked light curing machine for post-curing, with a total curing time of about 30 seconds.

[0167] The tensile strength anisotropy of the GF-Enamine-6 ​​reinforced photocurable composite material sample prepared in this embodiment is 7.6%, and the elongation at break anisotropy is 5.4%.

[0168] Example 7: Preparation of modified CF-reinforced photocurable composite material

[0169] The specific preparation method of the modified CF-reinforced photocurable composite material in this embodiment is as follows:

[0170] 1) Preparation of 4-vinylaniline modified carbon fiber CF-Enamine-7

[0171] 2g of carbon fiber (CF) was placed in a flask and 120ml of hydrochloric acid solution was added. The mixture was stirred at 90℃ for 5h. After the reaction was complete, the fiber was washed with deionized water and then dried in an oven at 60℃ for 12h to obtain oxidized carbon fiber (OCF).

[0172] OCF (1.2 g) and catalyst 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (0.60 g, 3.15 mmol) were added to 60 ml of N,N-dimethylformamide solution containing 4-vinylaniline (2 g, 14.8 mmol) and reacted at 150 °C under a nitrogen atmosphere for 2 h.

[0173] The fibers were then washed with N,N-dimethylformamide and dried in a vacuum oven at 60°C for 12 hours to obtain 4-ethylene aniline modified carbon fibers (denoted as CF-Enamine-7).

[0174] 2) Preparation of CF-Enamine-7 reinforced photocurable composite material

[0175] Bisphenol A epoxy acrylate (32g), hydroxyethyl acrylate (8g), and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (1.2g) were mixed to obtain a photosensitive resin.

[0176] Then, 0.8g of CF-Enamine-7 was added to the photosensitive resin (corresponding to an addition amount of 2wt.%), and dispersed at 3000r / min for 3min using a high-speed disperser to obtain a uniformly mixed CF-Enamine-7 reinforced photosensitive resin solution. After removing air bubbles, the solution was poured into a commercial 405nm DLP 3D printer to prepare CF-Enamine-7 reinforced photocurable composite material.

[0177] After printing, use ethanol to clean the residual resin solution on the sample surface, and then use a full-band tracked light curing machine for post-curing, with a total curing time of about 30 seconds.

[0178] The tensile strength anisotropy of the GF-Enamine-7 reinforced photocurable composite material sample prepared in this embodiment is 7.1%, and the elongation at break anisotropy is 5.5%.

[0179] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An isotropic photocurable material, characterized by, The isotropic photocurable material is a photosensitive resin in which 4-ethylene aniline-modified carbon fibers are distributed. The content of the 4-ethylene aniline-modified carbon fibers is 1-3 wt.% of the photosensitive resin. The 4-ethylene aniline-modified carbon fibers are formed by grafting 4-ethylene aniline onto the surface of the carbon fibers. The tensile strength anisotropy of the isotropic photocurable material is less than 11.0%, and the elongation at break anisotropy is less than 8.5%. The 4-ethyleneaniline modified carbon fiber is obtained by surface treatment of carbon fiber using 4-ethyleneaniline as raw material and a chemical grafting modification method. The specific method includes: (i) Carbon fiber CF is added to an acidic oxidizing agent to carry out an oxidation reaction, washed with water and dried to obtain oxidized carbon fiber OCF; (ii) Add OCF and catalyst to one of the following solutions of 4-vinylaniline: ethanol, isopropanol, and N,N-dimethylformamide, and carry out an amidation reaction under a nitrogen atmosphere; (iii) After the reaction was complete, the carbon fiber was washed with N,N-dimethylformamide and dried to obtain 4-ethyleneaniline modified carbon fiber CF-Enamine; The photosensitive resin is prepared by mixing epoxy acrylate, monofunctional acrylate monomer and photoinitiator.

2. The isotropic photocurable material of claim 1, wherein, The content of the 4-ethylene aniline modified carbon fiber is 2-3 wt. of the photosensitive resin.

3. The isotropic photocurable material according to claim 1, characterized in that, The isotropic photocurable material has a tensile strength anisotropy of less than 8.0% and an elongation at break anisotropy of less than 6.0%.

4. The isotropic photocurable material according to claim 3, characterized in that, The isotropic photocurable material has a tensile strength anisotropy of less than 4.0% and an elongation at break anisotropy of less than 2.5%.

5. The isotropic photocurable material according to claim 1, characterized in that, The tensile strength of the isotropic photocurable material is higher than 60 MPa.

6. The isotropic photocurable material according to claim 1, characterized in that, The isotropic photocurable material has an elongation at break of more than 5%.

7. The isotropic photocurable material according to claim 1, characterized in that, In the XPS wide scan spectrum, the isotropic photocurable material has C1s peaks of C=C, CC, N=CO and O=CO at 284.7 eV, 285.8 eV, 287.0 eV and 289.2 eV respectively.

8. The isotropic photocurable material according to claim 1, characterized in that, In step (i), the acidic oxidant is one or more of concentrated sulfuric acid and nitric acid.

9. The isotropic photocurable material according to claim 1, characterized in that, In step (i), the amount of acidic oxidant added is 50 to 200 ml, based on 2 g equivalent carbon fiber.

10. The isotropic photocurable material according to claim 1, characterized in that, In step (i), the oxidation reaction is carried out at a temperature of 50–100 °C for 2–10 h.

11. The isotropic photocurable material according to claim 1, characterized in that, In step (i), the drying includes vacuum drying at 50–120 °C for 6–12 h.

12. The isotropic photocurable material according to claim 1, characterized in that, In step (ii), the mass ratio of OCF to 4-vinylaniline is 0.5 to 3:

1.

13. The isotropic photocurable material according to claim 12, characterized in that, In step (ii), the mass ratio of OCF to 4-vinylaniline is 0.6 to 2.4:

1.

14. The isotropic photocurable material according to claim 1, characterized in that, In step (ii), the catalyst for the amidation reaction includes one or more of dicyclohexylcarbodiimide, 2-(7-azabenzotriazole)-N,N,N',N'-tetramethylurea hexafluorophosphate, and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide.

15. The isotropic photocurable material according to claim 1, characterized in that, In step (ii), the molar ratio of the catalyst to 4-ethyleneaniline is 1:2.0 to 3.

0.

16. The isotropic photocurable material according to claim 1, characterized in that, In step (ii), the amidation reaction is carried out at a temperature of 100–150 °C for 2–10 h. The use of 17,4-ethylene aniline modified carbon fiber in the preparation of isotropic photocurable materials, characterized in that... The isotropic photocurable material is the isotropic photocurable material according to any one of claims 1-7, and the 4-ethylene aniline modified carbon fiber is made by grafting 4-ethylene aniline onto the surface of the carbon fiber.

18. A method for preparing an isotropic photocurable material, characterized in that, The preparation method includes the following steps: (1) Using 4-ethyleneaniline as raw material, 4-ethyleneaniline modified carbon fibers are obtained by surface treatment of carbon fibers using a chemical grafting modification method; the specific method includes: (i) Carbon fiber CF is added to an acidic oxidizing agent to carry out an oxidation reaction, washed with water and dried to obtain oxidized carbon fiber OCF; (ii) Add OCF and catalyst to one of the following solutions of 4-vinylaniline: ethanol, isopropanol, and N,N-dimethylformamide, and carry out an amidation reaction under a nitrogen atmosphere; (iii) After the reaction was complete, the carbon fiber was washed with N,N-dimethylformamide and dried to obtain 4-ethyleneaniline modified carbon fiber CF-Enamine; (2) Epoxy acrylate, monofunctional acrylate monomer and photoinitiator are mixed to obtain photosensitive resin, and 4-ethylene aniline modified carbon fiber is added as a reinforcing phase. The content of 4-ethylene aniline modified carbon fiber is 1-3 wt.% of the photosensitive resin and it is evenly dispersed. Isotropic photocurable material is obtained by photocuring 3D printing.

19. The preparation method according to claim 18, characterized in that, In step (2), the monofunctional acrylate monomer includes one or more of isobornyl acrylate, dicyclopentadiene acrylate, hydroxyethyl acrylate, and tetrahydrofuran acrylate.

20. The preparation method according to claim 18, characterized in that, In step (2), the photoinitiator includes one or more of 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoyl-ethoxy-phenylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.

21. The preparation method according to claim 18, characterized in that, In step (2), the mass ratio of epoxy acrylate, monofunctional acrylate monomer and photoinitiator is 20-36:4-20:0.4-1.

2.

22. The preparation method according to claim 18, characterized in that, The content of the 4-ethylene aniline modified carbon fiber is 2-3 wt. of the photosensitive resin.

23. The preparation method according to claim 18, characterized in that, The dispersion time is 1 to 5 minutes.

24. The preparation method according to claim 18, characterized in that, The photopolymer 3D printing process involves post-curing, with the post-curing time being 10–50 seconds.

25. The preparation method according to claim 18, characterized in that, In step (i), the acidic oxidant is one or more of concentrated sulfuric acid and nitric acid.

26. The preparation method according to claim 18, characterized in that, In step (i), the amount of acidic oxidant added is 50 to 200 ml, based on 2 g equivalent carbon fiber.

27. The preparation method according to claim 18, characterized in that, In step (i), the oxidation reaction is carried out at a temperature of 50–100 °C for 2–10 h.

28. The preparation method according to claim 18, characterized in that, In step (i), the drying includes vacuum drying at 50–120 °C for 6–12 h.

29. The preparation method according to claim 18, characterized in that, In step (ii), the mass ratio of OCF to 4-vinylaniline is 0.5 to 3:

1.

30. The preparation method according to claim 29, characterized in that, In step (ii), the mass ratio of OCF to 4-vinylaniline is 0.6 to 2.4:

1.

31. The preparation method according to claim 18, characterized in that, In step (ii), the catalyst for the amidation reaction includes one or more of dicyclohexylcarbodiimide, 2-(7-azabenzotriazole)-N,N,N',N'-tetramethylurea hexafluorophosphate, and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide.

32. The preparation method according to claim 18, characterized in that, In step (ii), the molar ratio of the catalyst to 4-ethyleneaniline is 1:2.0 to 3.

0.

33. The preparation method according to claim 18, characterized in that, In step (ii), the amidation reaction is carried out at a temperature of 100–150 °C for 2–10 h.

34. The application of isotropic photocurable materials prepared according to any one of claims 1-16, or according to any one of claims 18-33, in the fields of medical devices, electronic components, automotive parts, or aerospace.

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