Modified fiber reinforced silicone rubber composite material as well as preparation method and application thereof

Abstract

The invention discloses a modified fiber reinforced silicone rubber composite material as well as a preparation method and application thereof. The preparation method of the modified fiber reinforced silicone rubber composite material comprises the following steps: 1) performing modification treatment on short fibers subjected to plasma treatment by adopting a modifier to obtain silicon modified short fibers; and 2) blending the silicon modified short fiber, an auxiliary agent and a silicone rubber matrix, then adding a cross-linking agent for mixing, and then performing vulcanization treatment to obtain the modified fiber reinforced silicone rubber composite material. By adopting the preparation method of the modified aramid fiber reinforced silicone rubber, the dispersity of the short fibers in a rubber matrix can be effectively improved, and the interface bonding performance of the short fibers and the rubber matrix can be improved, so that the mechanical property of a silicone rubber composite material can be effectively improved.

Description

Technical Field

[0001] The present invention belongs to the field of silicone rubber, and in particular relates to a modified fiber-reinforced silicone rubber composite material and a preparation method and application thereof. Background Art

[0002] High-temperature vulcanized silicone rubber, due to its unique molecular structure, is irreplaceable in the field of adaptability to extreme environments. In terms of thermal stability, HTV silicone rubber can maintain elastic deformation capabilities within a wide temperature range of -60°C to 250°C. In addition, high-temperature vulcanized silicone rubber also has excellent ozone and radiation resistance and good biocompatibility. However, due to the flexible characteristics of the polysiloxane molecular chain, the mechanical performance indicators of silicone rubber lag significantly behind engineering requirements. Even with the addition of fumed silica for reinforcement, its tear strength is still 15-25kN / m, which is difficult to meet the mechanical requirements of many application scenarios. This performance shortcoming seriously restricts its application. Chinese invention patents CN106589964B and CN104788965B both disclose a method for preparing silicone rubber with high tear strength. However, the high tear resistance achieved through centralized crosslinking is complex and has poor controllability. It requires precise control of the local diffusion of the crosslinking agent, and the amount of residual free radicals in the highly crosslinked area is large, which leads to accelerated thermal oxidation of the silicone rubber.

[0003] Aramid fiber, a representative of high-performance organic synthetic fibers, boasts a tensile strength of 2.8-3.5 GPa, 5-8 times that of steel. It also offers advantages such as high-temperature resistance, acid and alkali resistance, and lightweight construction. However, the interaction between aramid fiber and silicone rubber is poor. Therefore, improving the interaction between aramid fiber and silicone rubber, thereby enhancing the mechanical properties of silicone rubber through the fiber, is a pressing issue. Summary of the Invention

[0004] In order to overcome the problems existing in the prior art, the present invention provides the following technical solutions:

[0005] A method for preparing a modified fiber-reinforced silicone rubber composite material comprises the following steps:

[0006] 1) Modifying the plasma-treated short fibers with a modifier to obtain silicon-modified short fibers;

[0007] 2) The silicon-modified short fibers, the additives, and the silicone rubber matrix are blended, and then a cross-linking agent is added and kneaded, and then the mixture is vulcanized to obtain the modified fiber-reinforced silicone rubber composite material.

[0008] According to an embodiment of the present invention, in step 1), the plasma-treated short fibers are obtained by subjecting the short fibers to plasma treatment. Preferably, the plasma treatment time is 10 seconds to 1 hour, and the treatment power is 10W to 500W. Preferably, the short fibers after plasma treatment have more polar groups on their surfaces, which is more conducive to modification.

[0009] According to an embodiment of the present invention, the material of the short fibers is selected from at least one of aramid fibers, polyester fibers, polyamide fibers, polyimide fibers, acrylic fibers, polyolefin fibers, polybenzimidazole fibers, and polyetheretherketone fibers. Preferably, the short fibers are in the form of chopped fibers or pulp. Furthermore, the short fibers are selected from aramid chopped fibers and aramid pulp.

[0010] According to an embodiment of the present invention, when the short fibers are selected from aramid chopped fibers, they also need to be cleaned. Preferably, the cleaning process specifically includes: immersing in acetone for ultrasonic treatment for 0.5 to 4 hours to remove the surface treatment agent, followed by washing with ethanol 1 to 3 times, washing with deionized water 1 to 3 times, and drying in an oven at 40 to 150°C for 1 to 6 hours.

[0011] According to an embodiment of the present invention, in step 1), the modifier is selected from at least one of tetraethyl orthosilicate (TEOS), sodium silicate, a silane coupling agent, tetrabutyl titanate, silver nitrate, zinc nitrate, etc. Preferably, the modifier is selected from tetraethyl orthosilicate.

[0012] According to an embodiment of the present invention, in step 1), the modification treatment specifically includes: mixing the plasma-treated short fibers and a catalyst in a solvent, adding a modifier to react, and in situ growing nano-SiO2 on the surface of the short fibers to obtain silicon-modified short fibers.

[0013] Preferably, the catalyst is selected from ethanol and concentrated ammonia water, and the content of concentrated ammonia water is 0.1% to 10%.

[0014] Preferably, the solvent is selected from a mixture of water and anhydrous ethanol, and the mass ratio of water to anhydrous ethanol is 0:50 to 50:50.

[0015] Preferably, the plasma-treated short fibers and the catalyst are mixed in a solvent by first mixing the catalyst and solvent, and then adding the short fibers. Furthermore, after the catalyst and solvent are mixed, ultrasonic dispersion can be performed, for example, for 1 to 60 minutes. Furthermore, after the short fibers are added, ultrasonic pretreatment is performed for 0 to 3 hours.

[0016] According to an embodiment of the present invention, the concentration of the modifier is 0.01 to 1 mol / L.

[0017] According to an embodiment of the present invention, after the modifier is added, the reaction time is 1 to 8 hours, for example, 5 hours.

[0018] According to an embodiment of the present invention, after the modification reaction, the silicon-modified staple fibers may be washed and dried. Preferably, washing may be performed using methods known in the art, such as repeated washing with deionized water and anhydrous ethanol until the filtrate is neutral. Preferably, drying may be performed using methods known in the art, such as oven drying at 40-150°C for 1-6 hours.

[0019] According to an embodiment of the present invention, in step 2), the auxiliary agent is selected from at least one of white carbon black, carbon black, diatomaceous earth, kaolin, calcium carbonate, quartz powder, boron nitride, silicon carbide, carbon nanotubes, etc., for example, fumed white carbon black.

[0020] According to an embodiment of the present invention, in step 2), the silicone rubber matrix is selected from silicone rubber matrices known in the art; for example, methyl vinyl silicone rubber, with a molecular weight of not less than 100,000, preferably 100,000 to 1 million, for example 700,000.

[0021] According to an embodiment of the present invention, in step 2), blending can be performed using an apparatus known in the art, such as an internal mixer, where the shearing action of the internal mixer disperses the silicon-modified staple fibers in the silicone rubber matrix. Preferably, the blended mixture can be further mixed on a two-roll mill; illustratively, when the roll gap of the two-roll mill is at its thinnest, the silicon-modified staple fibers are evenly distributed in the silicone rubber matrix, and the silicon-modified staple fibers do not agglomerate.

[0022] According to an embodiment of the present invention, in step 2), the cross-linking agent is selected from at least one of dibenzoyl peroxide (BP), 2,4-dichlorobenzoyl peroxide (DCBP), tert-butyl perbenzoate (TBBP), di-tert-butyl peroxide (DTBP), diethylpropional benzene peroxide (DCP), and dipentadienyl methyl sulfoxide (DBPMH). Preferably, the cross-linking agent is selected from dipentadienyl methyl sulfoxide (DBPMH).

[0023] According to an embodiment of the present invention, in step 2), the mixing can be performed using a device known in the art, such as a two-roll mill. The mixing time is not specifically limited, for example, 10 min to 30 min.

[0024] According to an embodiment of the present invention, in step 2), after mixing and before vulcanization, the mixture may be allowed to stand at room temperature for 12-24 hours and then mixed for a second time; for example, after standing at room temperature for 24 hours, the mixture may be mixed for 20 minutes.

[0025] According to an embodiment of the present invention, in step 2), the vulcanization treatment includes one-stage vulcanization and two-stage vulcanization.

[0026] Preferably, the specific conditions of the one-stage vulcanization include: 1-20 MPa, 120-200° C., 1-20 min; for example, 12 MPa, 170° C., 10 min. Further, the one-stage vulcanization is carried out in a known device, for example, in a flat vulcanizing press.

[0027] Preferably, the conditions for the second stage vulcanization include: 150-250°C, 1-10 hours, for example, 200°C, 4 hours. Furthermore, the second stage vulcanization is carried out in a known device, for example, in a forced air drying oven.

[0028] The present invention also provides a modified fiber reinforced silicone rubber composite material. The raw materials of the modified fiber reinforced silicone rubber composite material include: 10-1000 parts by weight of silicone rubber matrix, 1-100 parts by weight of silicone modified short fibers, 1-500 parts by weight of additives, and 0.1-10 parts by weight of crosslinking agent.

[0029] According to an embodiment of the present invention, among the raw materials, the silicone rubber matrix, the auxiliary agent, and the cross-linking agent have the meanings as described above.

[0030] According to an embodiment of the present invention, the silicon-modified short fibers are preferably short fibers with nano-SiO2 in-situ grown on the surface of the short fibers, and the short fibers have the meaning as described above.

[0031] According to a preferred embodiment of the present invention, the raw materials include: 30-50 parts by weight of silicone rubber matrix, 1-5 parts by weight of silicone modified short fibers, 10-20 parts by weight of additives, and 0.1-0.5 parts by weight of crosslinking agent.

[0032] According to a preferred embodiment of the present invention, the raw materials include: 900-1000 parts by weight of silicone rubber matrix, 50-60 parts by weight of silicone modified short fibers, 400-500 parts by weight of additives, and 1-10 parts by weight of crosslinking agent.

[0033] According to an exemplary embodiment of the present invention, the raw materials include: 38 parts by weight of silicone rubber matrix, 1-3 parts by weight of silicone modified short fibers, 17 parts by weight of auxiliary agent, and 0.3-0.35 parts by weight of cross-linking agent.

[0034] According to an exemplary embodiment of the present invention, the raw materials include: 950 parts by weight of silicone rubber matrix, 50-60 parts by weight of silicone modified short fibers, 450 parts by weight of auxiliary agent, and 7.5 parts by weight of cross-linking agent.

[0035] According to the solution of the present invention, the modified fiber-reinforced silicone rubber composite material has at least one of the following properties:

[0036] (1) 100% modulus of tensile stress is not less than 2 MPa;

[0037] (2) 300% modulus of elongation is not less than 5 MPa;

[0038] (3) Tear strength not less than 36KN / m;

[0039] (4) Shore A hardness not less than 65.

[0040] According to an embodiment of the present invention, the modified fiber-reinforced silicone rubber composite material is obtained by the above-mentioned preparation method.

[0041] The present invention also provides applications of the modified fiber-reinforced silicone rubber composite material, such as for use in at least one of a sealing ring, a cable, an insulator, a conveyor belt, and the like.

[0042] Beneficial effects

[0043] The preparation method of the modified aramid-reinforced silicone rubber of the present invention can effectively improve the dispersion of short fibers (such as aramid chopped fibers or aramid pulp) in the rubber matrix (especially silicone rubber) and improve the interfacial bonding performance between the short fibers and the rubber matrix, thereby effectively improving the mechanical properties of the silicone rubber composite material, such as tensile strength, 100% modulus stress, 300% modulus stress, and tear strength. DETAILED DESCRIPTION

[0044] The technical solutions of the present invention will be described in further detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are encompassed within the scope of protection that the present invention is intended to protect.

[0045] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0046] Fumed silica: HD153 from Shandong Hongruitong New Material Technology Co., Ltd.

[0047] Methyl vinyl silicone rubber: Dongjue Silicone Co., Ltd. 110-2 type, vinyl content of 0.16%, molecular weight of 700,000;

[0048] Aramid pulp: purchased from Yantai Taihe New Materials Co., Ltd., model is Taipron pulp 1820;

[0049] Aramid chopped short fibers: purchased from Yantai Taihe New Materials Co., Ltd., model is Taipron short chopped 3mm type.

[0050] Example 1

[0051] The preparation method of the modified fiber reinforced silicone rubber composite material is as follows:

[0052] (1) Immerse the aramid short fibers in an acetone solution and ultrasonically treat for 2 h to remove the surface treatment agent. Rinse with ethanol three times, then with deionized water three times, and dry in an oven at 80°C for 4 h.

[0053] (2) The aramid chopped fibers obtained in step (1) were treated in a vacuum plasma treatment machine at 100 W for 10 min.

[0054] (3) 4 mL of distilled water and 90 mL of anhydrous ethanol were mixed, 6 mL of concentrated ammonia was added as a catalyst, and ultrasonic dispersion was performed for 30 min. Then, 3 g of the aramid short fibers obtained in step (2) were added and ultrasonic pretreated for 2 h. Tetraethyl orthosilicate (TEOS) with a concentration of 0.05 mol / L was quickly added and reacted for 4 h. After the reaction was completed, the modified aramid short fibers were taken out, washed and dried, and then used for later use. The washing and drying specifically included: washing with deionized water and anhydrous ethanol repeatedly in sequence until the filtrate was neutral; and finally drying in an oven at 100°C for 4 h.

[0055] (4) 38 g of methyl vinyl silicone rubber, 17 g of fumed silica, and 2 g of the modified aramid short fibers obtained in step (3) were added to an internal mixer and mixed for 1 h.

[0056] (5) The mixture after mixing in the internal mixer was further mixed on a two-roll mill for 30 minutes until the roller spacing was about 20 μm, the fiber distribution was very uniform, and no agglomeration of the aramid chopped fibers was observed by naked eye. 0.3 g of di-2-pentane was added as a crosslinking agent and mixed on the two-roll mill for 10 minutes.

[0057] (6) After standing at room temperature for 24 hours, the sample was refining for 20 minutes and subjected to a first stage of vulcanization on a flat plate vulcanizing press under the following conditions: 12 MPa, 170 ° C, 10 minutes.

[0058] The modified fiber-reinforced silicone rubber composite material was obtained by performing two-stage vulcanization in a forced air drying oven at 200°C for 4 hours.

[0059] Example 2

[0060] The preparation method of the modified fiber reinforced silicone rubber composite material is as follows:

[0061] (1) Immerse the aramid short fibers in an acetone solution and ultrasonically treat for 1 hour to remove the surface treatment agent. Rinse with ethanol three times, then with deionized water three times, and dry in a 120°C oven for 2 hours.

[0062] (2) The aramid chopped fibers obtained in step (1) were treated in a vacuum plasma treatment machine at 150 W for 5 min.

[0063] (3) 4 mL of distilled water and 90 mL of anhydrous ethanol were mixed, 6 mL of concentrated ammonia water was added as a catalyst, and ultrasonic dispersion was performed for 10 min. Then, 3 g of aramid short fibers obtained by the treatment in step (2) were added and ultrasonic pretreatment was performed for 1 h. Tetraethyl orthosilicate (TEOS) with a concentration of 0.1 mol / L was quickly added and reacted for 4 h. After the reaction was completed, the modified aramid short fibers were taken out, washed and dried, and then used for later use. The washing and drying specifically included: washing with deionized water and anhydrous ethanol repeatedly in sequence until the filtrate was neutral; and finally drying in a 100°C oven for 4 h.

[0064] (4) 38 g of methyl vinyl silicone rubber, 17 g of fumed silica, and 2.8 g of the modified aramid short fibers obtained in step (3) were added to an internal mixer and mixed for 2 h.

[0065] (5) The mixture after mixing in the internal mixer was further mixed on a two-roll mill for 30 minutes until the roller spacing was about 20 μm, the fiber distribution was very uniform, and no agglomeration of the aramid chopped fibers was observed by naked eye. 0.3 g of di-2-pentane was added as a crosslinking agent and mixed on the two-roll mill for 10 minutes.

[0066] (6) After standing at room temperature for 24 hours, the sample was refining for 20 minutes and subjected to a first stage of vulcanization on a flat plate vulcanizing press under the following conditions: 12 MPa, 170 ° C, 10 minutes.

[0067] The second stage vulcanization was carried out in a forced air drying oven at 200°C for 4 hours.

[0068] Example 3

[0069] The preparation method of the modified fiber reinforced silicone rubber composite material is as follows:

[0070] (1) Aramid pulp was treated in a vacuum plasma treatment machine at 100 W for 10 min.

[0071] (2) 4 mL of distilled water and 90 mL of anhydrous ethanol were mixed, 6 mL of concentrated ammonia water was added as a catalyst, and ultrasonic dispersion was performed for 30 min. Then, 3 g of the aramid pulp treated in step (1) was added and ultrasonic pre-treated for 2 h. Tetraethyl orthosilicate (TEOS) with a concentration of 0.2 mol / L was quickly added and reacted for 4 h. After the reaction was completed, the modified aramid pulp was taken out, washed and dried, and then used for later use. The washing and drying specifically included: washing with deionized water and anhydrous ethanol repeatedly in sequence until the filtrate was neutral; and finally drying in a 100°C oven for 4 h.

[0072] (3) 38 g of methyl vinyl silicone rubber, 17 g of fumed silica, and 2 g of the aramid pulp obtained in step (2) were added to an internal mixer and mixed for 3 h.

[0073] (4) The mixture after mixing in the internal mixer was further mixed on a two-roll mill for 1 hour until the roller spacing was about 20 μm, the fiber distribution was very uniform, and no aramid pulp agglomeration was observed by naked eye. 0.3 g of di-2-pentane was added as a crosslinking agent and mixed on the two-roll mill for 10 minutes.

[0074] (5) After standing at room temperature for 24 hours, the sample was refining for 20 minutes and subjected to a first stage of vulcanization on a flat plate vulcanizing press under the following conditions: 12 MPa, 170 ° C, 10 minutes.

[0075] The modified fiber-reinforced silicone rubber composite material was obtained by performing two-stage vulcanization in a forced air drying oven at 200°C for 4 hours.

[0076] Example 4

[0077] The preparation method of the modified fiber reinforced silicone rubber composite material is as follows:

[0078] (1) Aramid pulp was treated in a vacuum plasma treatment machine at 200 W for 5 min.

[0079] (2) 4 mL of distilled water and 90 mL of anhydrous ethanol were mixed, 6 mL of concentrated ammonia water was added as a catalyst, and ultrasonic dispersion was carried out for 30 min. Then, 3 g of the aramid pulp obtained by the treatment in step (1) was added and ultrasonic pretreatment was carried out for 2 h. Tetraethyl orthosilicate (TEOS) with a concentration of 0.05 mol / L was quickly added and reacted for 4 h. After the reaction was completed, the modified aramid pulp was taken out, washed and dried, and then used for standby use. The washing and drying specifically included: washing with deionized water and anhydrous ethanol repeatedly in sequence until the filtrate was neutral; and finally drying in a 100°C oven for 4 h.

[0080] (3) 38 g of methyl vinyl silicone rubber, 17 g of fumed silica, and 1.2 g of the modified aramid pulp obtained in step (2) were added to an internal mixer and mixed for 2 h.

[0081] (4) The mixture after mixing in the internal mixer was further mixed on a two-roll mill for 2 h, until the roll gap was approximately 20 μm, the fiber distribution was very uniform, and no aramid pulp agglomeration was observed visually. 0.3 g of di-2-pentane was added as a crosslinking agent and mixed on the two-roll mill for 10 min.

[0082] (5) After standing at room temperature for 24 hours, the sample was refining for 20 minutes and subjected to a first stage of vulcanization on a flat plate vulcanizing press under the following conditions: 12 MPa, 170 ° C, 10 minutes.

[0083] The modified fiber-reinforced silicone rubber composite material was obtained by performing two-stage vulcanization in a forced air drying oven at 200°C for 4 hours.

[0084] Example 5

[0085] The preparation method of the modified fiber reinforced silicone rubber composite material is as follows:

[0086] (1) Immerse the aramid short fibers in an acetone solution and ultrasonically treat for 1.5 h to remove the surface treatment agent. Rinse with ethanol three times, then with deionized water three times, and dry in a 100°C oven for 3 h.

[0087] (2) The aramid chopped fibers treated in step (1) were treated in a vacuum plasma treatment machine at 100 W for 10 min.

[0088] (3) 0.13 L of distilled water and 3 L of anhydrous ethanol were mixed, 0.2 L of concentrated ammonia water was added as a catalyst, and ultrasonic dispersion was performed for 30 min. Then, 100 g of aramid short fibers treated in step (2) were added and ultrasonic pre-treated for 2 h. Tetraethyl orthosilicate (TEOS) with a concentration of 0.07 mol / L was quickly added and reacted for 6 h. After the reaction, the aramid short fibers were taken out, washed and dried, and then set aside. The washing and drying specifically included: washing with deionized water and anhydrous ethanol repeatedly in sequence until the filtrate was neutral; and finally drying in an oven at 100 ° C for 4 h.

[0089] (4) 0.95 kg of methyl vinyl silicone rubber, 0.45 kg of fumed silica, and 60 g of the modified aramid short fibers obtained in step (3) were added to an internal mixer and mixed for 4 h.

[0090] (5) The mixture after mixing in the internal mixer was further mixed on a two-roll mill for 1 hour until the roller spacing was about 20 μm, the fiber distribution was very uniform, and no agglomeration of the aramid chopped fibers was observed by naked eye. 7.5 g of di-2-pentane was added as a crosslinking agent and mixed on the two-roll mill for 10 minutes.

[0091] (6) After standing at room temperature for 24 hours, the sample was refining for 20 minutes and subjected to a first stage of vulcanization on a flat plate vulcanizing press under the following conditions: 12 MPa, 170 ° C, 10 minutes.

[0092] The modified fiber-reinforced silicone rubber composite material was obtained by performing two-stage vulcanization in a forced air drying oven at 200°C for 4 hours.

[0093] Example 6

[0094] The preparation method of the modified fiber reinforced silicone rubber composite material is as follows:

[0095] (1) Aramid pulp was treated in a vacuum plasma treatment machine at 150 W for 10 min.

[0096] (2) 0.13 L of distilled water and 3 L of anhydrous ethanol were mixed, 0.2 L of concentrated ammonia water was added as a catalyst, and ultrasonic dispersion was performed for 20 min. Then, 100 g of the aramid pulp treated in step (1) was added and ultrasonic pre-treated for 2 h. Tetraethyl orthosilicate (TEOS) with a concentration of 0.05 mol / L was quickly added and reacted for 5 h. After the reaction was completed, the modified aramid pulp was taken out, washed and dried, and then used for later use. The washing and drying specifically included: washing with deionized water and anhydrous ethanol repeatedly in sequence until the filtrate was neutral; and finally drying in an oven at 100°C for 4 h.

[0097] (3) 0.95 kg of methyl vinyl silicone rubber, 0.45 kg of fumed silica, and 50 g of the modified aramid pulp obtained in step (2) were added to an internal mixer and mixed for 2 h.

[0098] (4) The mixture after mixing in the internal mixer was further mixed on a two-roll mill for 6 hours until the roller spacing was about 20 μm, the fiber distribution was very uniform, and no aramid pulp agglomeration was observed by naked eye. 7.5 g of di-2-pentane was added as a crosslinking agent and mixed on the two-roll mill for 10 minutes.

[0099] (5) After standing at room temperature for 24 hours, the sample was refining for 20 minutes and subjected to a first stage of vulcanization on a flat plate vulcanizing press under the following conditions: 12 MPa, 170 ° C, 10 minutes.

[0100] The modified fiber-reinforced silicone rubber composite material was obtained by performing two-stage vulcanization in a forced air drying oven at 200°C for 4 hours.

[0101] Comparative Example 1

[0102] The preparation method of silicone rubber composite material is as follows:

[0103] (1) Add 38g of methyl vinyl silicone rubber and 17g of fumed silica into an internal mixer and mix for 1h.

[0104] (2) The mixture after mixing in the internal mixer is further mixed on a double-roll mill.

[0105] 30 minutes. Add 0.3g of dipentadiene as a cross-linking agent and mix on a two-roll mill for 10 minutes.

[0106] (3) After standing at room temperature for 24 hours, the sample was refining for 20 minutes and subjected to a first stage of vulcanization on a flat plate vulcanizing press under the following conditions: 12 MPa, 170 ° C, 10 minutes.

[0107] Two-stage vulcanization was carried out in a forced air drying oven at 200° C. for 4 h to obtain a silicone rubber composite material, which was designated as comparative material 1.

[0108] Comparative Example 2

[0109] The preparation method of the fiber reinforced silicone rubber composite material is as follows:

[0110] (1) 38 g of methyl vinyl silicone rubber, 17 g of fumed silica, and 2 g of untreated aramid short fibers were added to an internal mixer and mixed for 1 h.

[0111] (2) The mixture after mixing in the internal mixer was further mixed on a two-roll mill for 30 minutes until the roller spacing was about 20 μm, the fiber distribution was very uniform, and no agglomeration of the aramid chopped fibers was observed by naked eye. 0.3 g of di-2-pentane was added as a crosslinking agent and mixed on the two-roll mill for 10 minutes.

[0112] (3) After standing at room temperature for 24 hours, the sample was refining for 20 minutes and subjected to a first stage of vulcanization on a flat plate vulcanizing press under the following conditions: 12 MPa, 170 ° C, 10 minutes.

[0113] Two-stage vulcanization was carried out in a forced air drying oven at 200° C. for 4 h to obtain a fiber-reinforced silicone rubber composite material, which was designated as comparative material 2.

[0114] Comparative Example 3

[0115] The preparation method of the fiber reinforced silicone rubber composite material is as follows:

[0116] (1) 38 g of methyl vinyl silicone rubber, 17 g of fumed silica, and 2 g of untreated aramid pulp were added to an internal mixer and mixed for 3 h.

[0117] (2) The mixture after mixing in the internal mixer was further mixed on a two-roll mill for 1 hour until the roller spacing was about 20 μm, the fiber distribution was very uniform, and no aramid pulp agglomeration was observed by naked eye. 0.3 g of di-2-pentane was added as a crosslinking agent and mixed on the two-roll mill for 10 minutes.

[0118] (3) After standing at room temperature for 24 hours, the sample was refining for 20 minutes and subjected to a first stage of vulcanization on a flat plate vulcanizing press under the following conditions: 12 MPa, 170 ° C, 10 minutes.

[0119] Two-stage vulcanization was carried out in a forced air drying oven at 200° C. for 4 h to obtain a fiber-reinforced silicone rubber composite material, which was recorded as comparative material 3.

[0120] The mechanical properties of the high temperature vulcanized silicone rubbers prepared in the above examples and comparative examples are recorded in Table 1.

[0121] The reference standard for tensile testing is GB / T 528-2009.

[0122] The reference standard for tearing test is GB / T 529-2009.

[0123] Table 1

[0124]

[0125]

[0126] From Table 1 we can see that:

[0127] Comparative examples show that when unmodified aramid is compounded with silicone rubber, the resulting material exhibits slightly improved 100% and 300% modulus of elongation and tear strength, but a decrease in tensile strength. The examples show that when modified aramid is compounded with silicone rubber, the resulting material exhibits improved 100% and 300% modulus of elongation, tensile strength, and tear strength compared to the untreated aramid and silicone rubber composite. Furthermore, by adjusting the amount of modified aramid, the tensile strength remains unchanged, while the 100% modulus of elongation, 300% modulus of elongation, and tear strength are significantly increased.

[0128] The above describes exemplary embodiments of the present invention. However, the scope of protection of this application is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc. made by those skilled in the art within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a modified fiber-reinforced silicone rubber composite material, characterized in that: It includes the following steps: 1) Modifying the plasma-treated short fibers with a modifier to obtain silicon-modified short fibers; 2) The silicon-modified short fibers, the additives, and the silicone rubber matrix are blended, and then a cross-linking agent is added and kneaded, and then the mixture is vulcanized to obtain the modified fiber-reinforced silicone rubber composite material.

2. The preparation method according to claim 1, characterized in that In step 1), the plasma-treated short fibers are obtained by treating the short fibers with plasma; The material of the short fiber is at least one selected from aramid fiber, polyester fiber, polyamide fiber, polyimide fiber, acrylic fiber, polyolefin fiber, polybenzimidazole fiber, and polyetheretherketone fiber; When the short fibers are selected from aramid short fibers, they also need to be cleaned.

3. The preparation method according to claim 1 or 2, characterized in that In step 1), the modifier is selected from at least one of tetraethyl orthosilicate, sodium silicate, silane coupling agent, tetrabutyl titanate, silver nitrate, and zinc nitrate; In step 1), the modification treatment specifically includes: mixing the plasma-treated short fibers and a catalyst in a solvent, adding a modifier to react, and in situ growing nano-SiO2 on the surface of the short fibers to obtain silicon-modified short fibers; The concentration of the modifier is 0.01 to 1 mol / L; After adding the modifier, the reaction time is 1 to 8 hours.

4. The preparation method according to claim 1, characterized in that In step 2), the auxiliary agent is selected from at least one of white carbon black, carbon black, diatomaceous earth, kaolin, calcium carbonate, quartz powder, boron nitride, silicon carbide, carbon nanotubes, etc.; In step 2), the cross-linking agent is selected from at least one of dibenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butyl perbenzoate, di-tert-butyl peroxide, diethyl propyl benzene peroxide, and dipentadiene.

5. The preparation method according to claim 1 or 4, characterized in that In step 2), after mixing and before vulcanization, the mixture is allowed to stand at room temperature for 12-24 hours, and then mixed again for the second time; In step 2), the vulcanization treatment includes one-stage vulcanization and two-stage vulcanization; The specific conditions of the first stage vulcanization include: 1-20MPa, 120-200℃, 1-20min; The conditions for the second stage vulcanization include: 150-250°C, 1-10h.

6. A modified fiber reinforced silicone rubber composite material, characterized in that: The raw materials of the modified fiber reinforced silicone rubber composite material include: 10-1000 parts by weight of silicone rubber matrix, 1-100 parts by weight of silicone modified short fibers, 1-500 parts by weight of auxiliary agent, and 0.1-10 parts by weight of crosslinking agent.

7. The modified fiber reinforced silicone rubber composite material according to claim 6, characterized in that: The silicon-modified short fibers are short fibers with nano-SiO2 grown in situ on the surface of the short fibers.

8. The modified fiber reinforced silicone rubber composite material according to claim 6 or 7, characterized in that: The raw materials include: 30-50 parts by weight of silicone rubber matrix, 1-5 parts by weight of silicone modified short fibers, 10-20 parts by weight of additives, and 0.1-0.5 parts by weight of cross-linking agent; Alternatively, the raw materials include: 900-1000 parts by weight of silicone rubber matrix, 50-60 parts by weight of silicone modified short fibers, 400-500 parts by weight of auxiliary agent, and 1-10 parts by weight of cross-linking agent.

9. The modified fiber reinforced silicone rubber composite material according to any one of claims 6 to 8, characterized in that: The modified fiber-reinforced silicone rubber composite material has at least one of the following properties: (1) 100% modulus of tensile stress is not less than 2 MPa; (2) 300% modulus of elongation is not less than 5 MPa; (3) Tear strength not less than 36KN / m; (4) Shore A hardness not less than 65; And / or, the modified fiber-reinforced silicone rubber composite material is obtained by the above-mentioned preparation method.

10. Use of the modified fiber reinforced silicone rubber composite material according to any one of claims 6 to 9 in the fields of sealing rings, cables, insulators, and conveyor belts.

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