Flexible mold for forming liquid conduction pressure composite material and preparation method of flexible mold

Abstract

The invention discloses a flexible mold for forming a liquid conduction pressure composite material and a preparation method of the flexible mold, and relates to the technical field of composite material forming, the mold is formed by compounding a fiber net reinforcing material and a silicon rubber material, the compounding ratio of the silicon rubber to a fiber net is 70: 30-90: 10, and the composite material is a composite material. The characteristic of uniform pressure conduction is realized through the silicone rubber-fiber net composite layer; according to the flexible mold for forming the liquid conduction pressure composite material and the preparation method of the flexible mold, by introducing the fiber net reinforcing layer, the tear resistance and puncture resistance of the flexible mold are remarkably improved, and the flexible mold has a wide working temperature range and can be repeatedly used for not less than 50 times through experimental verification; the problems of poor ductility, difficulty in operation, disposable use and the like caused by insufficient high-temperature resistance, poor tolerance to resin solvents and excessive thickening for compensating the strength of the existing nitrile rubber mold are solved, and the production cost and the labor intensity of workers are greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of composite material molding technology, specifically to a flexible mold for molding liquid-conducting pressure composite materials and its preparation method. Background Technology

[0002] Liquid-conducting pressure molding is a key process for manufacturing high-performance composite material components in aerospace, defense, and other fields. This process relies on a flexible mold to form a closed pressure chamber above the composite material preform, uniformly transferring the high temperature and pressure applied by the liquid medium to the preform surface. This ensures that the component possesses excellent mechanical properties and low porosity after curing. In this process, the performance of the flexible mold directly determines the stability of the molding process and the final quality of the component.

[0003] Currently, nitrile rubber (NBR) is the most widely used flexible mold material in liquid-conducting pressure composite molding processes. However, NBR has revealed several fatal flaws in actual processes:

[0004] First, it has insufficient high-temperature resistance. When the molding temperature exceeds 150℃, the molecular chains of nitrile rubber will degrade and cross-link, causing the material to harden and undergo irreversible deformation. It will fail after one molding cycle and can only be used once.

[0005] Second, it has poor resistance to resin solvents. During the molding process of composite materials, nitrile rubber may swell or degrade with the solvent components in the resin system, affecting the molding accuracy.

[0006] Third, insufficient mechanical strength leads to excessive thickness. To compensate for the strength deficiency, nitrile rubber molds usually need to be significantly thickened, resulting in reduced mold flexibility, difficulty in operation, and increased labor intensity for workers.

[0007] Fourth, it is not economically viable. Due to the aforementioned performance defects, nitrile rubber molds can only be used once, and new molds must be replaced after each molding cycle. This not only leads to high raw material costs but also results in low production efficiency and equipment downtime losses.

[0008] Therefore, there is an urgent need in this field for a flexible mold material that can withstand high temperature environments and resin solvents, and also has good flexibility and durability, in order to solve the problems of poor flexibility and difficult operation caused by excessive thickness of traditional molds, as well as the resulting problems of frequent mold replacement and high costs. Summary of the Invention

[0009] The purpose of this invention is to provide a flexible mold for molding liquid-conducting pressure composite materials and its preparation method, so as to solve the problems of insufficient high temperature resistance, poor resistance to resin solvents, easy aging, tearing, and the resulting frequent mold replacement and high cost in the existing nitrile rubber flexible molds.

[0010] To achieve the above objectives, the present invention provides the following technical solution: a flexible mold for molding liquid-conducting pressure composite materials, wherein the mold is made of fiber mesh reinforcement material and silicone rubber material, and the composite ratio of silicone rubber to fiber mesh is 70:30 to 90:10, and the silicone rubber-fiber mesh composite layer achieves the characteristic of uniform pressure transmission; the molding of liquid-conducting pressure composite materials refers to the process of transmitting pressure through water or oil-based hydraulic medium to cure and form prepreg in a closed mold.

[0011] Furthermore, the silicone rubber material includes at least one of methyl silicone rubber, methyl vinyl silicone rubber, phenyl silicone rubber, fluorosilicone rubber, nitrile silicone rubber, ethyl silicone rubber, phenyl ether silicone rubber, long-chain alkyl modified silicone rubber, and silicone nitrogen rubber; wherein, when two or more silicone rubbers are blended, the mass percentage of each component is 10% to 90%.

[0012] Furthermore, the phenyl silicone rubber includes at least one of high-phenyl silicone rubber, medium-phenyl silicone rubber, and low-phenyl silicone rubber.

[0013] Furthermore, the fiber web reinforcement material includes at least one of nonwoven fabric, metal mesh, aramid fiber web, carbon fiber fabric, glass fiber fabric, and basalt fiber fabric.

[0014] Furthermore, the flexible mold is suitable for composite material liquid conduction pressure molding process, which includes hydraulic autoclave, hydraulic tank molding process or vacuum bag pressing process, and has a cycle life of not less than 50 times under hydraulic pressure of 0.1 to 12 MPa.

[0015] This invention also discloses a method for preparing a flexible mold for molding liquid-conducting pressure composite materials, specifically including the following steps:

[0016] S1. Weigh out the silicone rubber material and disperse it evenly at room temperature to obtain the silicone rubber matrix;

[0017] S2. Cut the fiber web to the required size, wipe it with anhydrous ethanol and pretreat the surface of the fiber web to obtain a surface-activated fiber web.

[0018] S3. Lay the surface-activated fiber mesh flat on the coating platform, and then coat the silicone rubber matrix onto one side of the surface-activated fiber mesh to form a composite layer;

[0019] S4. Place the composite layer into the preheated flat vulcanizing mold and perform hot-press vulcanization treatment to obtain a flexible mold.

[0020] Furthermore, in S2, the surface pretreatment of the fiber web adopts at least one of plasma treatment, silane coupling agent coating, and ultraviolet irradiation; the power of the plasma treatment is set to 500-1000W, the concentration of the silane coupling agent coating is set to 1-3wt% hydrolysis solution (the solvent is a mixture of ethanol and water, volume ratio 9:1), and the ultraviolet irradiation time is set to 3-8 minutes.

[0021] Furthermore, the coating method in S3 is at least one of scraping, spraying, and impregnation; the composite layer in S3 is a double-layer structure of silicone rubber matrix covering fiber mesh.

[0022] Furthermore, in S4, the temperature for hot-press vulcanization is set to 160℃~180℃, the pressure is set to 8~12MPa, and the vulcanization time is set to 30~45 minutes.

[0023] Compared with the prior art, the flexible mold for molding liquid-conducting pressure composite materials and its preparation method provided by the present invention have the following beneficial effects:

[0024] (1) Excellent temperature resistance: The silicone rubber matrix has a wide working temperature range. Experiments show that it can maintain stable performance in the range of -60℃ to 250℃, meeting the requirements of most composite material molding processes.

[0025] (2) Good solvent resistance: It has excellent resistance to common solvents in resin systems, avoiding swelling and performance degradation.

[0026] (3) Excellent mechanical properties: The fiber mesh reinforced structure enables the mold to still have high tear resistance and puncture resistance even when the thickness is relatively thin, thus solving the contradiction between strength and flexibility.

[0027] (4) Service life is significantly extended and economic efficiency is greatly improved: Experimental verification shows that it can be reused no less than 50 times, which completely changes the limitation of traditional nitrile rubber molds being used only once, and the cost per use is reduced by more than 90%.

[0028] (5) Easy to operate: Good flexibility and moderate thickness make mold installation and disassembly simple, significantly reducing labor intensity. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0030] Figure 1This is a schematic diagram of the preparation method of a flexible mold for molding liquid-conducting pressure composite materials provided by the present invention. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0032] Example 1:

[0033] Please see Figure 1 A flexible mold for molding liquid-conducting pressure composite materials is made of fiber mesh reinforcement material and silicone rubber material, wherein the silicone rubber material is methyl vinyl silicone rubber with a mass percentage of 100%, the fiber mesh reinforcement material is glass fiber fabric, and the composite ratio of silicone rubber to fiber mesh is 70:30; the flexible mold is suitable for liquid-conducting pressure molding processes of composite materials, including but not limited to hydraulic autoclave, hydraulic tank molding processes, and vacuum bag pressing processes.

[0034] The specific steps in preparing this flexible mold are as follows:

[0035] S1. Weigh out methyl vinyl silicone rubber and disperse it evenly at room temperature to obtain a silicone rubber matrix;

[0036] S2. Cut the fiber web to the required size, wipe it with anhydrous ethanol, and place it in the working chamber of the plasma treatment equipment. Pre-treat the surface of the glass fiber fabric under a power of 800W for 60s to obtain a surface-activated fiber web.

[0037] S3. Lay the surface-activated fiber mesh flat on the coating platform, and then coat the silicone rubber matrix onto one side of the surface-activated fiber mesh by scraping to form a composite layer.

[0038] S4. Place the composite layer into the preheated flat vulcanizing mold and perform hot-press vulcanization treatment. Set the hot-pressing temperature to 170℃, the pressure to 10MPa, and the time to 40 minutes to obtain a flexible mold.

[0039] The prepared flexible mold was trimmed with a trimming accuracy controlled within ±0.5 mm. The flexible mold was inspected, and the test results showed that the flexible mold had excellent flexibility under hydraulic pressure of 0.1 to 10 MPa, maintained stable performance in the range of -60℃ to 250℃, and had a high temperature resistance of up to 250℃. It was able to withstand 50 cycles without damage.

[0040] Example 2:

[0041] Please see Figure 1This embodiment provides a technical solution based on Embodiment 1: a flexible mold for molding liquid-conducting pressure composite materials, which is made of fiber mesh reinforcement material and silicone rubber material, wherein the silicone rubber material is high-phenyl silicone rubber, medium-phenyl silicone rubber and low-phenyl silicone rubber in a mass ratio of 1:1:1, the fiber mesh reinforcement material is carbon fiber fabric, and the composite ratio of silicone rubber to fiber mesh is 70:30; this flexible mold is suitable for liquid-conducting pressure molding process of composite materials, which includes but is not limited to hydraulic autoclave, hydraulic tank molding process and vacuum bag pressing process.

[0042] The specific steps in preparing this flexible mold are as follows:

[0043] S1. Weigh high-phenyl silicone rubber, medium-phenyl silicone rubber and low-phenyl silicone rubber in a mass ratio of 1:1:1, mix them at room temperature until they are evenly dispersed to obtain a silicone rubber matrix;

[0044] S2. Cut the fiber web to the required size, wipe it with anhydrous ethanol, and then pretreat the surface of the carbon fiber fabric with a 3% concentration of silane coupling agent solution to obtain a surface-activated fiber web.

[0045] S3. Lay the surface-activated fiber mesh flat on the coating platform, and then coat the silicone rubber matrix onto one side of the surface-activated fiber mesh by spraying to form a composite layer.

[0046] S4. Place the composite layer into the preheated flat vulcanizing mold and perform hot-press vulcanization treatment. Set the hot-pressing temperature to 180℃, the pressure to 12MPa, and the time to 35 minutes to obtain a flexible mold.

[0047] The prepared flexible mold was trimmed with a trimming accuracy controlled within ±0.5 mm. The flexible mold was inspected, and the test results showed that the flexible mold had excellent flexibility under hydraulic pressure of 0.1 to 12 MPa, maintained stable performance in the range of -60℃ to 250℃, and was undamaged after 60 cycles. Its high temperature resistance reached 250℃.

[0048] Example 3:

[0049] Please see Figure 1 This embodiment provides a technical solution based on Embodiment 1: a flexible mold for molding liquid-conducting pressure composite materials, which is made of fiber mesh reinforcement material and silicone rubber material, wherein the silicone rubber material is fluorosilicone rubber with a mass percentage of 100%, the fiber mesh reinforcement material is aramid fiber mesh, and the composite ratio of silicone rubber to fiber mesh is 70:30; this flexible mold is suitable for liquid-conducting pressure molding process of composite materials, which includes but is not limited to hydraulic autoclave, hydraulic tank molding process, and vacuum bag pressing process.

[0050] The specific steps in preparing this flexible mold are as follows:

[0051] S1. Weigh out fluorosilicone rubber and disperse it evenly at room temperature to obtain a silicone rubber matrix;

[0052] S2. Cut the fiber web to the required size, wipe it with anhydrous ethanol, and then pretreat the surface of the aramid fiber web with a 3% concentration of silane coupling agent solution to obtain a surface-activated fiber web.

[0053] S3. Lay the surface-activated fiber mesh flat on the coating platform, and then coat the silicone rubber matrix onto one side of the surface-activated fiber mesh by spraying to form a composite layer.

[0054] S4. Place the composite layer into the preheated flat vulcanizing mold and perform hot-press vulcanization treatment. Set the hot-pressing temperature to 185℃, the pressure to 9MPa, and the time to 45 minutes to obtain a flexible mold.

[0055] The prepared flexible mold was trimmed with a trimming accuracy controlled within ±0.5 mm. The flexible mold was inspected, and the test results showed that the flexible mold had excellent flexibility under hydraulic pressure of 0.1 to 9 MPa, maintained stable performance in the range of -60℃ to 250℃, and was undamaged after 50 cycles.

[0056] Example 4:

[0057] Please see Figure 1 This embodiment provides a technical solution based on Embodiment 1: a flexible mold for molding liquid-conducting pressure composite materials, which is made of fiber mesh reinforcement material and silicone rubber material, wherein the silicone rubber material is methyl silicone rubber and ethyl silicone rubber in a mass ratio of 7:3, the fiber mesh reinforcement material is metal mesh, and the composite ratio of silicone rubber and fiber mesh is 90:10; this flexible mold is suitable for liquid-conducting pressure molding process of composite materials, which includes but is not limited to hydraulic autoclave, hydraulic tank molding process, and vacuum bag pressing process.

[0058] The specific steps in preparing this flexible mold are as follows:

[0059] S1. Weigh out methyl silicone rubber and ethyl silicone rubber in a mass ratio of 7:3 and mix them at room temperature until they are evenly dispersed to obtain a silicone rubber matrix;

[0060] S2. Cut the fiber mesh to the required size, wipe it with anhydrous ethanol, and place it in the working chamber of the plasma processing equipment. Pre-treat the surface of the metal mesh under a power of 800W for 60s to obtain a surface-activated fiber mesh.

[0061] S3. Lay the surface-activated fiber mesh flat on the coating platform, and then coat the silicone rubber matrix onto one side of the surface-activated fiber mesh by impregnation to form a composite layer.

[0062] S4. Place the composite layer into the preheated flat vulcanizing mold and perform hot-press vulcanization treatment. Set the hot-pressing temperature to 170℃, the pressure to 10MPa, and the time to 40 minutes to obtain a flexible mold.

[0063] The prepared flexible mold was trimmed with a trimming accuracy controlled within ±0.5 mm. The flexible mold was inspected, and the test results showed that the flexible mold has excellent flexibility under hydraulic pressure of 0.1 to 10 MPa, can maintain stable performance in the range of -60℃ to 250℃, can withstand high temperature up to 250℃, and can be cycled 50 times without damage, making it suitable for oil-based hydraulic media.

[0064] Comparative Example 1:

[0065] The flexible mold in this comparative example uses pure silicone rubber as raw material, without using fiber mesh material to enhance the performance of the silicone rubber. The silicone rubber material is specifically methyl vinyl silicone rubber, with a mass percentage of 100%.

[0066] The specific steps in preparing this flexible mold are as follows:

[0067] S1. Weigh out methyl vinyl silicone rubber and disperse it evenly at room temperature to obtain a silicone rubber matrix;

[0068] S2. Place the silicone rubber matrix into the preheated flat vulcanizing mold and perform hot-press vulcanization treatment. Set the hot-pressing temperature to 170℃, the pressure to 10MPa, and the time to 40 minutes to obtain a flexible mold.

[0069] The prepared flexible mold was trimmed with a trimming accuracy controlled within ±0.5 mm. The flexible mold was inspected, and the test results showed that the high temperature resistance of the flexible mold was significantly reduced. It tore after 10 cycles under hydraulic pressure of 0.1 to 10 MPa, and its lifespan was short.

[0070] Comparative Example 2:

[0071] The flexible mold in this comparative example is made of a composite of ordinary rubber (silicone-free rubber) and fiber mesh reinforcement material. The silicone-free rubber material is nitrile rubber, and the fiber mesh reinforcement material is glass fiber fabric. The composite ratio of nitrile rubber and glass fiber fabric is 70:30.

[0072] The specific steps in preparing this flexible mold are as follows:

[0073] S1. Weigh out nitrile rubber and disperse it evenly at room temperature to obtain nitrile rubber matrix;

[0074] S2. Cut the fiber web to the required size, wipe it with anhydrous ethanol, and then pretreat the surface of the glass fiber fabric with a 3% concentration of silane coupling agent solution to obtain a surface-activated fiber web.

[0075] S3. Lay the surface-activated fiber web flat on the coating platform, and then coat the nitrile rubber matrix onto one side of the surface-activated fiber web by spraying to form a composite layer.

[0076] S4. Place the composite layer into the preheated flat vulcanizing mold and perform hot-press vulcanization treatment. Set the hot-pressing temperature to 120℃, the pressure to 10MPa, and the time to 60 minutes to obtain a flexible mold.

[0077] The prepared flexible mold was trimmed with a trimming accuracy controlled within ±0.5 mm. The flexible mold was inspected, and the test results showed that after one use in a hydraulic autoclave at 150℃, the flexible mold aged rapidly, exhibited obvious hardening and permanent deformation, and had uneven pressure transmission, making it unusable.

[0078] Comparative Example 3:

[0079] The flexible mold in this comparative example is made of a composite of fiber mesh reinforcement material and silicone rubber material, wherein the silicone rubber material is fluorosilicone rubber with a mass percentage of 100%, and the fiber mesh reinforcement material is carbon fiber fabric.

[0080] The method for preparing this flexible mold omits surface pretreatment and specifically includes the following steps:

[0081] S1. Weigh out fluorosilicone rubber and disperse it evenly at room temperature to obtain a silicone rubber matrix;

[0082] S2. Lay the carbon fiber fabric flat on the coating platform, and then coat the silicone rubber matrix onto one side of the carbon fiber fabric by spraying to form a composite layer.

[0083] S3. Place the composite layer into the preheated flat vulcanizing mold and perform hot-press vulcanization treatment. The hot-pressing temperature is set to 170℃, the pressure is set to 10MPa, and the time is set to 40 minutes to obtain a flexible mold.

[0084] The prepared flexible mold was trimmed with a trimming accuracy controlled within ±0.5 mm. The flexible mold was inspected, and the test results showed that the silicone rubber coating of the flexible mold prepared without pretreatment had poor adhesion. It could maintain stable performance at a high temperature of 250℃, but it was prone to delamination under high pressure of 0.1~10MPa. Interface failure occurred after 10 cycles, and the pressure transmission uniformity was poor.

[0085] In summary, this invention, through the construction of a core architecture of "fiber mesh reinforced silicone rubber composite material," prepares a flexible mold. This mold, made of fiber mesh reinforced silicone rubber composite material, is suitable for liquid-conducting pressure composite molding processes, solving the problems of existing nitrile rubber molds such as insufficient high-temperature resistance, poor resistance to resin solvents, poor ductility due to excessive thickening to compensate for strength, difficult operation, and single-use. The flexible mold of this invention, by introducing a fiber mesh reinforcement layer, significantly improves tear and puncture resistance, has a wide operating temperature range, and experimental verification shows it can be reused at least 50 times, completely changing the limitation of traditional nitrile rubber molds to single use, and greatly reducing production costs and worker labor intensity.

[0086] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A flexible mold for molding liquid-conducting pressure composite materials, characterized in that, The mold is made of a composite of fiber mesh reinforcement material and silicone rubber material, and the silicone rubber-fiber mesh composite layer achieves the characteristic of uniform pressure transmission.

2. The flexible mold for molding liquid-conducting pressure composite materials according to claim 1, characterized in that, The silicone rubber material includes at least one of methyl silicone rubber, methyl vinyl silicone rubber, phenyl silicone rubber, fluorosilicone rubber, nitrile silicone rubber, ethyl silicone rubber, phenyl ether silicone rubber, long-chain alkyl modified silicone rubber, and silicone nitrogen rubber.

3. The flexible mold for molding liquid-conducting pressure composite materials according to claim 2, characterized in that, The phenyl silicone rubber includes at least one of high-phenyl silicone rubber, medium-phenyl silicone rubber, and low-phenyl silicone rubber.

4. The flexible mold for molding liquid-conducting pressure composite materials according to claim 1, characterized in that, The fiber web reinforcement material includes at least one of nonwoven fabric, metal mesh, aramid fiber web, carbon fiber fabric, glass fiber fabric, and basalt fiber fabric.

5. A method for preparing a flexible mold for molding liquid-conducting pressure composite materials, characterized in that, Its use in preparing a flexible mold for molding a liquid-conducting pressure composite material as described in any one of claims 1-4 specifically includes the following steps: S1. Weigh out the silicone rubber material and disperse it evenly at room temperature to obtain the silicone rubber matrix; S2. Cut the fiber web to the required size, wipe it with anhydrous ethanol and pretreat the surface of the fiber web to obtain a surface-activated fiber web. S3. Lay the surface-activated fiber mesh flat on the coating platform, and then coat the silicone rubber matrix onto one side of the surface-activated fiber mesh to form a composite layer; S4. Place the composite layer into the preheated flat vulcanizing mold and perform hot-press vulcanization treatment to obtain a flexible mold.

6. The method for preparing a flexible mold for molding liquid-conducting pressure composite materials according to claim 5, characterized in that, The surface pretreatment of the fiber web in S2 is at least one of plasma treatment, silane coupling agent coating, and ultraviolet irradiation; the power of the plasma treatment is set to 500-1000W, the concentration of the silane coupling agent coating is set to 1-3wt% hydrolysis solution, and the ultraviolet irradiation time is set to 3-8 minutes.

7. The method for preparing a flexible mold for molding liquid-conducting pressure composite materials according to claim 5, characterized in that, The coating method in S3 is at least one of scraping, spraying, and impregnation; the composite layer in S3 is a double-layer structure of silicone rubber matrix covering fiber mesh.

8. The method for preparing a flexible mold for molding liquid-conducting pressure composite materials according to claim 5, characterized in that, In S4, the hot-press vulcanization temperature is set to 160℃~180℃, the pressure is set to 8~12MPa, and the vulcanization time is set to 30~45 minutes.

9. The flexible mold according to claim 1, characterized in that, The flexible mold is suitable for composite material liquid conduction pressure molding process, which includes hydraulic autoclave, hydraulic tank molding process or vacuum bag pressing process.

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