Preparation method of filter green body formed by hydantoin epoxy resin gel injection system

Abstract

The invention discloses a preparation method of a filter green body formed by a hydantoin epoxy resin gel injection system, ceramic filters with low, medium and high dielectric constants are prepared by using a hydantoin epoxy resin system, high suitability of the system is verified, hydroxyethyl acrylate HEA is introduced as a flexibilizer, on one hand, internal stress generated during complex green body forming is eliminated, and on the other hand, the high adaptability of the system is improved; on the other hand, the microwave drying box ensures that the internal and external temperatures of the green body are consistent and synchronous drying is realized, HEA improves the nitrogen-hydrogen bond energy of an amine group of the hydantoin epoxy resin, water molecules move in a small range, the drying efficiency is improved, and meanwhile, the internal net structure of the green body is stable; the defects that the green body warps and cracks are generated when the wet ceramic green body is dried are effectively overcome, and the green body which is uniform in shrinkage and smooth in surface is obtained; the obtained green body is high in strength and compact in microstructure, and has the advantages of low cost, capability of manufacturing complex shapes, simple process and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of microwave ceramic filter guides, and particularly relates to a method for preparing a filter blank formed by a hydantoin epoxy resin injection molding system. Background Art

[0002] Microwave dielectric ceramics refer to ceramics that are used as dielectric materials in microwave frequency band circuits and perform one or more functions. Usually, the dielectric properties are measured by three main performance parameters: dielectric constant (εr), quality factor (Q×f), and temperature coefficient of resonant frequency (τf). Low dielectric constant, high quality factor, and near-zero temperature coefficient of resonant frequency enable microwave dielectric ceramics to be widely used in microwave communication devices. Among them, ceramic filters are indispensable electronic devices in 5G communication technology.

[0003] At present, the main methods for forming ceramic filters are dry pressing, 3D printing, and gel casting. Dry pressing is widely used in industrial production and has the advantages of high precision and fast forming. However, the high mold cost and uneven product density limit its development; 3D printing, as a new technology, can realize rapid design and production of devices. However, the problems such as fewer compatible printing materials and difficulties in post-processing of closed structure cavities affect the application of 3D printing technology; the drying time of the blank of the traditional injection molding system is long, and due to the existence of temperature difference gradient, the product has uneven density.

[0004] Hydantoin epoxy resin is made by condensing 5,5-dimethylhydantoin and epichlorohydrin, and contains a five-membered diazacyclic ring in the molecule. By carrying out ring-opening addition reaction with a curing agent to form a three-dimensional network structure, the slurry is fixed in-situ, which has the advantages of low cost, good water solubility, and high strength.

[0005] In the research process of microwave dielectric ceramic filters, the following patents have been applied in the prior art: For example, in patent document CN104292717B, the application of hydantoin epoxy resin is disclosed, and a composite material with high energy storage density under low electric field is prepared by a hydantoin epoxy resin gel casting system, effectively overcoming the problems of poor compatibility and uneven mixing between inorganic ceramics and organic polymer materials.

[0006] In patent document CN104292717B, a forming method of an environmentally friendly water-based gel system silicon nitride ceramic substrate is disclosed. An isobutylene maleic anhydride copolymer (ISOBAM) solution is mixed with ceramic powder, and after ball milling with an organic solvent, a ceramic slurry is obtained. Finally, a silicon nitride ceramic substrate is prepared by combining a coating equipment.

[0007] In the patent document CN107759230B, a toughened ceramic gel casting method is disclosed. Ceramic powder is added to an organic monomer solution such as acrylamide, combined with a crosslinking agent and a catalyst, which improves the drying rate of the green body and prepares a ceramic green body with certain toughness.

[0008] In the patent document CN215790578U, a mold frame structure specially designed for complex products of 5G ceramic filters is provided. By adding a set of lower punch template structures to the mold, the stamping pressure becomes more reasonable and the quality of the mold is improved.

[0009] In the patent document CN214589176U, a 5G ceramic filter substrate forming process and its surface metallization technology are disclosed. The ceramic powder is physically dry-pressed into a ceramic dielectric green body, and the surfaces of the ceramic substrate, the inner surface of the mounting groove, and the inner surface of the blind hole are metallized by a multi-arc ion plating process.

[0010] However, in the patent document CN104292717B, the hydantoin epoxy resin gel casting system is applied to the field of energy storage materials. It is not easy for those skilled in the art to think of applying it to the field of forming microwave devices in this application, and the application fields are different. In the patent document CN104292717B, isobutene maleic anhydride copolymer is used as the monomer, and the plasticizer is one or a mixture of polyethylene glycol and glycerol. In the patent document CN107759230B, the organic monomers are any one of acrylamide, methacrylamide, N-methylolacrylamide, N-N'methylene bisacrylamide, methacrylamide, acrylic acid, methacrylic acid, and hydroxyethyl acrylate, and the plasticizer is polyethylene glycol, polymethacrylamide, glycerol, or triethylene glycol diacetate. In the present invention, hydantoin epoxy resin monomer and hydroxyethyl acrylate (HEA) are used as toughening agents, which can produce a synergistic effect. In the patent documents CN215790578U and CN214589176U, due to the complex shape of the filter and the presence of small through holes in the middle, the small through rods of the mold have to bear a high pressure during the dry pressing process, which increases the manufacturing cost of the mold and cannot guarantee the high precision of the device, and also has a greater impact on the final performance of the filter. Summary of the Invention

[0011] Technical problems to be solved:

[0012] In view of the deficiencies in the prior art, such as high mold costs, uneven product density, few compatible printing materials, difficult post-treatment for sealed structure cavities, long drying time of green bodies in traditional injection-casting systems, uneven product density due to the existence of temperature difference gradients, inability to ensure high precision of devices, and significant impact on the final performance of filters, this application provides a preparation method for forming filter green bodies using a hydantoin epoxy resin injection-casting system. Three types of ceramic filters with low, medium, and high dielectric constants are prepared using the hydantoin epoxy resin system, verifying the high adaptability of this system. Hydroxyethyl acrylate (HEA) is introduced as a toughening agent. On the one hand, it eliminates the internal stress generated during the forming of complex green bodies, ensuring the quality of the green bodies. On the other hand, through a microwave drying oven, the temperature inside and outside the green body is made consistent to achieve synchronous drying. HEA increases the bond energy of the nitrogen-hydrogen bond in the amine group of the hydantoin epoxy resin, allowing water molecules to move within a small range. While improving the drying efficiency, the internal network structure of the green body remains stable, effectively overcoming the disadvantages of warping and cracking of the ceramic green body during drying, and obtaining a green body with uniform shrinkage and a smooth surface. The obtained green body has high strength, a dense microstructure, and advantages such as low cost, the ability to produce complex shapes, and simple processes.

[0013] Technical solution:

[0014] To achieve the above objectives, this application is realized through the following technical solutions:

[0015] A preparation method for forming filter green bodies using a hydantoin epoxy resin injection-casting system, the specific steps are as follows:

[0016] First step: Take microwave dielectric ceramic powder and sinter it in a muffle furnace at 200°C to 800°C for 3 to 9 hours;

[0017] Second step: According to the mass-volume ratio, add 10 - 20 parts of the gelling agent hydantoin epoxy resin MHR070 to 100 parts of deionized water to make a premixed solution with a concentration of 10% - 20%, and add a dispersant relative to 1% - 4% of the mass of the microwave dielectric ceramic powder. Then add a pH regulator, and add the microwave dielectric ceramic powder in three portions at room temperature and place it on a ball mill for ball milling for 6 - 8 hours to obtain a slurry;

[0018] Third step: Add 2 - 4 parts of a curing agent to the slurry, add a toughening agent relative to 0.5% - 1.5% of the mass of the microwave dielectric ceramic powder, and place it in a ball mill at room temperature for ball milling for 5 - 15 minutes;

[0019] Fourth step: Use 3D software to make a ceramic waveguide filter mold, degas the slurry after ball milling in the third step under vacuum, and inject the degassed slurry into the mold to obtain a green body;

[0020] Fifth step: Demold the green body and place it in a microwave vacuum drying oven for drying;

[0021] Step 6: Place the dried green body in a sintering furnace for debinding and sintering. After sintering, a formed filter body of the hydantoin epoxy injection molding system is obtained.

[0022] Further, in the first step, the microwave dielectric ceramic powder is a high dielectric constant microwave dielectric ceramic powder, a medium dielectric constant microwave dielectric ceramic powder, or a low dielectric constant microwave dielectric ceramic powder; the dielectric constant of the high dielectric constant microwave dielectric ceramic powder is 90, the dielectric constant of the medium dielectric constant microwave dielectric ceramic powder is 45, and the dielectric constant of the low dielectric constant microwave dielectric ceramic powder is 9.

[0023] Further, in the first step, the high dielectric constant microwave dielectric ceramic powder, the medium dielectric constant microwave dielectric ceramic powder, and the low dielectric constant microwave dielectric ceramic powder are abbreviated as K90, K45, and K9 microwave dielectric ceramic powders, respectively. The purity of the high dielectric constant microwave dielectric ceramic powder, the medium dielectric constant microwave dielectric ceramic powder, and the low dielectric constant microwave dielectric ceramic powder is ≥99.91%.

[0024] Further, in the second step, the dispersant is one or more of polyacrylic acid, ammonium polyacrylate, and ammonium citrate, the pH regulator is an acidic or basic regulator, the pH value of the slurry is 3 - 5 or 8 - 10, and the rotation speed of the ball mill is 500 - 600 r / min.

[0025] Further, in the third step, the curing agent is one or more of polyethyleneimine, dipropyltriamine, and m - xylylenediamine, the toughening agent is hydroxyethyl acrylate (HEA), and the rotation speed of the ball mill in the third step is 200 - 600 r / min.

[0026] Further, in the fourth step, the ceramic waveguide filter is a cross - coupled waveguide filter, and the mold material is one of silicone, resin, and soft rubber; the vacuum degree for vacuum degassing is - 10 KPa to - 20 KPa, the vacuum degassing time is 1 - 3 min, and the size of the green body obtained after injecting the degassed slurry into the mold is: 42*20*6.2 mm.

[0027] Further, in the fifth step, the power of the microwave vacuum drying oven is 500 - 2000 W, and the drying time is 5 - 15 min.

[0028] Further, in the sixth step, the sintering method is integrated debinding and sintering. The debinding stage is specifically to heat up from room temperature to 200℃ - 260℃ at a rate of 1℃ / min and hold for 1 - 2 hours, then heat up from 260℃ to 500℃ - 560℃ and hold for 1 - 2 hours. The heating rate in the sintering stage is 2℃ / min, the sintering temperature is 1360℃ - 1600℃, and hold for 3 - 5 hours, and then cool down to room temperature with the furnace.

[0029] Principle explanation: The gel casting of this application is a process in which the slurry undergoes a polymerization reaction to form a shape spontaneously. The reaction is easy to control, the operation is simple, and complex structures can be formed with net dimensions. The present invention uses microwave drying. The water molecules in the slurry collide and rub as the direction of the electric field changes, the temperature of the product increases, and the heating is uniform, making the drying rate tend to be consistent and the curing speed of the green body increase. In the slurry preparation stage, the present invention introduces hydroxyethyl acrylate (HEA) as a toughening agent. Through the interaction between HEA and the polymer molecular chain, the spatial network structure is "softened", greatly reducing the stress generated at the through grooves and blind holes during the curing stage of the green body, and obtaining a high-quality green body. In addition, in the microwave drying stage, HEA increases the bond energy of the nitrogen-hydrogen bond of the amine group of the hydantoin epoxy resin, enabling the water molecules to move within a limited range. The network space structure inside the green body is intact, and at the same time, warping of the green body during the sintering process is avoided, ensuring the device performance.

[0030] Beneficial effects:

[0031] This application provides a preparation method for forming a filter green body with a hydantoin epoxy resin casting system. Compared with the prior art, it has the following beneficial effects:

[0032] 1. The present invention provides a method for forming a filter green body with a hydantoin epoxy resin casting system, using hydantoin epoxy resin as an organic monomer. This system has strong adaptability and can prepare microwave dielectric ceramic filters suitable for low, medium, and high dielectric constants. Compared with the traditional dry pressing method, the three obtained green bodies all meet the production indicators and have more advantages in dielectric properties.

[0033] 2. The present invention introduces hydroxyethyl acrylate (HEA) as a toughening agent, effectively reducing the internal stress during the forming stage of the green body with complex shapes, avoiding cracks in the green body, and ensuring the quality of the green body.

[0034] 3. The present invention optimizes a rapid drying method for the green body. After the green body is demolded, it is placed in a microwave drying oven. The green body is heated evenly, and the internal and external drying rates are the same. HEA increases the bond energy of the nitrogen-hydrogen bond of the amine group of the hydantoin epoxy resin, and the water molecules move within a small range. While improving the drying efficiency, the internal network structure of the green body is stable, effectively overcoming the disadvantages of warping and cracking of the ceramic green body during drying, and obtaining a green body with uniform shrinkage and smooth surface. Description of the drawings

[0035] Figure 1 It is a photo of a filter formed with a hydantoin epoxy resin casting system obtained in the embodiment of this application. Among them, (a) is a photo of the K90 sintered sample, (b) is a photo of the K45 sintered sample, and (c) is a photo of the K9 sintered sample;

[0036] Figure 2It is the structural formula and schematic diagram of hydroxyethyl acrylate (HEA) in the embodiments of this application. Among them, (a) is the molecular structure diagram of hydroxyethyl acrylate, (b) is the schematic diagram without adding hydroxyethyl acrylate, and (c) is the schematic diagram after adding hydroxyethyl acrylate;

[0037] Figure 3 It is the comparison photo of the effect of adding hydroxyethyl acrylate in this application. Among them, (a) is the green body photo without adding hydroxyethyl acrylate, and (b) is the green body photo after adding hydroxyethyl acrylate. Detailed implementation manners

[0038] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail in combination with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but should not be used to limit the protection scope of the present invention.

[0039] The hydantoin epoxy resin MHR070 described in this application is purchased from Wuxi Huilong Electronic Materials Co., Ltd.

[0040] Example 1

[0041] A preparation method for forming a filter green body of a hydantoin epoxy resin injection molding system, the specific steps are as follows:

[0042] The first step: Take K90 microwave dielectric ceramic powder with a purity ≥ 99.91%, and sinter it in a muffle furnace at three different temperatures of 200 °C, 400 °C and 800 °C for 3 hours, 3 hours, and 3 hours respectively;

[0043] The second step: According to the mass-volume ratio, add 2.22 g of the gel agent hydantoin epoxy resin MHR070 to 20 g of deionized water to make a premixed solution with a concentration of 10%, and add 0.8 g of polyacrylic acid dispersant relative to 1% of the mass of the microwave dielectric ceramic powder, add a pH regulator to make the pH value of the solution 10. The K90 powder is added to the ball mill in three times, which are 35 g, 35 g, and 10 g respectively, and placed on the ball mill to ball mill for 6 hours at a speed of 600 r / min to obtain a slurry;

[0044] The third step: Add 0.5 g of the curing agent polyethyleneimine and 0.4 g of the plasticizer hydroxyethyl acrylate (HEA) to the slurry, and place it in the ball mill at room temperature to ball mill for 10 minutes at 400 r / min;

[0045] The fourth step: Use 3D software to make a silicone mold for a cross-coupled waveguide filter. The slurry after ball milling in the third step is degassed under vacuum at a vacuum degree of -10 KPa, and the vacuum degassing time is 3 min. The slurry after vacuum degassing is poured into the mold to obtain a green body, and the size of the green body is: 42 * 20 * 6.2 mm;

[0046] The fifth step: Demold the green body and place it in a 1000W microwave vacuum drying oven to dry for 10 min;

[0047] Step 6: Place the dried green body in a sintering furnace for debinding and sintering. The sintering method is integrated debinding and sintering. Specifically, in the debinding stage, the temperature is raised from room temperature to 260°C at a rate of 1°C / min and held for 2 hours, then raised from 260°C to 560°C and held for 2 hours. In the sintering stage, the heating rate is 2°C / min, the sintering temperature is 1560°C, and it is held for 5 hours, and then cooled to room temperature with the furnace to obtain the formed filter body of the hydantoin epoxy resin injection molding system.

[0048] Example 2

[0049] A preparation method of a formed filter body of a hydantoin epoxy resin injection molding system, the specific steps are as follows:

[0050] Step 1: Take K45 microwave dielectric ceramic powder with a purity ≥ 99.91%, and sinter it in a muffle furnace at three different temperatures of 200°C, 400°C, and 800°C for 3 hours, 3 hours, and 3 hours respectively;

[0051] Step 2: Prepare a premixed solution with a concentration of 14.9% by adding 3.5 g of the gelling agent hydantoin epoxy resin MHR070 to 20 g of deionized water according to the mass-to-volume ratio, and add 1.2 g of polyacrylic acid dispersant relative to 1.5% of the mass of the microwave dielectric ceramic powder, add a pH regulator to make the pH value of the solution 10. The K45 powder is added to the ball mill in three portions, 35 g, 35 g, and 10 g respectively, and ball milled on the ball mill at a speed of 500 r / min for 7 hours to obtain a slurry;

[0052] Step 3: Add 0.7 g of the curing agent polyethyleneimine and 0.8 g of the plasticizer hydroxyethyl acrylate (HEA) to the slurry, and place it in the ball mill at room temperature and ball mill at 300 r / min for 15 minutes;

[0053] Step 4: Use 3D software to make a silica gel mold for a cross-coupled waveguide filter. Vacuum degas the slurry after ball milling in the third step at a vacuum degree of -15 KPa for 2 min. Inject the degassed slurry into the mold to obtain a green body, and the size of the green body is: 42*20*6.2 mm;

[0054] Step 5: Demold the green body and place it in a 500 W microwave vacuum drying oven for drying for 15 min;

[0055] Step 6: Place the dried green body in a sintering furnace for debinding and sintering. The sintering method is integrated debinding and sintering. Specifically, in the debinding stage, the temperature is raised from room temperature to 260°C at a rate of 1°C / min and held for 2 hours, 260°C

[0056] Heat to 560 °C and hold for 2 hours. The heating rate during the sintering stage is 2 °C / min, the sintering temperature is 1480 °C, and hold for 3 hours. Cool to room temperature in the furnace to obtain a formed filter blank of the hydantoin epoxy resin injection molding system.

[0057] Example 3

[0058] A preparation method of a formed filter blank of the hydantoin epoxy resin injection molding system, the specific steps are as follows:

[0059] First step: Take K9 microwave dielectric ceramic powder with a purity ≥ 99.91%, and sinter it in a muffle furnace at three different temperatures of 200 °C, 400 °C, and 800 °C for 3 hours, 3 hours, and 3 hours respectively;

[0060] Second step: Prepare a premixed solution with a concentration of 20% by adding 5 g of the gelling agent hydantoin epoxy resin to 20 g of deionized water according to the mass-volume ratio, and add 1.2 g of polyacrylic acid dispersant relative to 1.5% of the mass of the microwave dielectric ceramic powder, a dispersant relative to 0.5% - 1.5% of the mass of the microwave dielectric ceramic powder, add a pH regulator to make the pH value of the solution 10. The K9 powder is added to the ball mill in three portions, which are 35 g, 35 g, and 10 g respectively, and placed on the ball mill to ball mill for 8 hours at a rotation speed of 600 r / min to obtain a slurry;

[0061] Third step: Add 1 g of the curing agent polyethyleneimine and 1.2 g of the plasticizer hydroxyethyl acrylate (HEA) to the slurry, and place it in the ball mill at room temperature to ball mill for 15 minutes at 300 r / min;

[0062] Fourth step: Use 3D software to make a silicone mold for a cross-coupled waveguide filter. Vacuum degas the slurry after ball milling in the third step under a vacuum of -20 KPa. The vacuum degassing time is 1 min. Inject the degassed slurry into the mold to obtain a green body. The size of the green body is: 42 * 20 * 6.2 mm;

[0063] Fifth step: Demold the green body and place it in a 2000W microwave vacuum drying oven to dry for 5 min;

[0064] Sixth step: Place the dried green body in a sintering furnace for debinding and sintering. The sintering method is an integrated debinding and sintering. The specific debinding stage is to heat from room temperature to 260 °C at a rate of 1 °C / min and hold for 2 hours, heat from 260 °C to 560 °C and hold for 2 hours. The heating rate during the sintering stage is 2 °C / min, the sintering temperature is 1380 °C, and hold for 3 hours. Cool to room temperature in the furnace to obtain a formed filter blank of the hydantoin epoxy resin injection molding system.

[0065] Table 1 Performance comparison of microwave dielectric ceramic powder processing methods

[0066]

[0067]

[0068] The selected embodiments in the above materials are for easy understanding and do not limit the process method. Those skilled in the same technical field can easily modify the process flow or transfer it to other cases without creative changes. If these changes also belong to the same type of claims or the same type of technology of the present invention, then the original intention of the invention also includes these changes.

Claims

1. A preparation method for forming a filter blank using a hydantoin epoxy resin injection molding system, characterized in that, The specific steps are as follows: Step 1: Take the microwave dielectric ceramic powder and sinter it in a muffle furnace at 200°C to 800°C for 3 to 9 hours; Step 2: According to the mass ratio, add 10 to 20 parts of the gelling agent, hexahydrophthalic anhydride epoxy resin MHR070, to 100 parts of deionized water to make a premixed solution with a concentration of 10% to 20%. Add a dispersant accounting for 1% to 4% of the mass of the microwave dielectric ceramic powder, and then add a pH regulator. Add the microwave dielectric ceramic powder in three portions at room temperature and place it on a ball mill for ball milling for 6 to 8 hours to obtain a slurry; Step 3: Add 2 to 4 parts of a curing agent to the slurry, add a toughening agent accounting for 0.5% to 1.5% of the mass of the microwave dielectric ceramic powder, and place it in a ball mill at room temperature for ball milling for 5 to 15 minutes; Step 4: Use 3D software to make a ceramic waveguide filter mold. Degas the slurry obtained after ball milling in the third step under vacuum. Inject the degassed slurry into the mold to obtain a green body; Step 5: Demold the green body and place it in a microwave vacuum drying oven for drying; Step 6: Place the dried green body in a sintering furnace for debinding and sintering, and obtain a formed filter body of the hexahydrophthalic anhydride epoxy resin injection molding system after sintering.

2. The preparation method of a filter blank formed by a hydantoin epoxy resin injection molding system according to claim 1, wherein: In the first step, the microwave dielectric ceramic powder is a high dielectric constant microwave dielectric ceramic powder, a medium dielectric constant microwave dielectric ceramic powder, or a low dielectric constant microwave dielectric ceramic powder; the dielectric constant of the high dielectric constant microwave dielectric ceramic powder is 90, the dielectric constant of the medium dielectric constant microwave dielectric ceramic powder is 45, and the dielectric constant of the low dielectric constant microwave dielectric ceramic powder is 9.

3. The preparation method of a molded filter blank of a hydantoin epoxy resin injection molding system according to claim 2, characterized in that: In the first step, the high dielectric constant microwave dielectric ceramic powder, the medium dielectric constant microwave dielectric ceramic powder, and the low dielectric constant microwave dielectric ceramic powder are abbreviated as K90, K45, and K9 microwave dielectric ceramic powders respectively, and the purity of the high dielectric constant microwave dielectric ceramic powder, the medium dielectric constant microwave dielectric ceramic powder, and the low dielectric constant microwave dielectric ceramic powder is ≥99.91%.

4. The preparation method of a filter blank formed by a hydantoin epoxy resin injection molding system according to claim 1, characterized in that: In the second step, the dispersant is one or more of polyacrylic acid, ammonium polyacrylate, and ammonium citrate, the pH regulator is an acidic or basic regulator, the pH value of the slurry is 3 to 5 or 8 to 10, and the rotation speed of the ball mill is 500 to 600 r / min.

5. The preparation method of a filter blank formed by a hydantoin epoxy resin injection molding system according to claim 1, characterized in that: In the third step, the curing agent is one or more of polyethyleneimine, dipropyltriamine, and m-xylenediamine, the toughening agent is hydroxyethyl acrylate HEA, and the rotation speed of the ball mill in the third step is 200 to 600 r / min.

6. The preparation method of a filter blank formed by a hydantoin epoxy resin injection molding system according to claim 1, characterized in that: In the fourth step, the ceramic waveguide filter is a cross-coupled waveguide filter, and the mold material is one of silicone, resin, and soft rubber; the vacuum degree for degassing is -10 KPa to -20 KPa, the degassing time is 1 - 3 min, and the size of the green body obtained by injecting the degassed slurry into the mold is: 42*20*6.2mm.

7. The preparation method of a filter blank formed by a hydantoin epoxy resin injection molding system according to claim 1, characterized in that: In the fifth step, the power of the microwave vacuum drying oven is 500 to 2000 W, and the drying time is 5 to 15 min.

8. The preparation method of a filter blank formed by a hydantoin epoxy resin injection molding system according to claim 1, characterized in that: In the sixth step, the sintering method is integrated debinding and sintering. Specifically, in the debinding stage, the temperature is raised from room temperature to 200°C - 260°C at a rate of 1°C / min and held for 1 - 2 hours, then raised from 260°C to 500°C - 560°C and held for 1 - 2 hours. In the sintering stage, the heating rate is 2°C / min, the sintering temperature is 1360°C - 1600°C, and it is held for 3 - 5 hours, and then cooled to room temperature with the furnace.

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