High-strength tear-resistant rubber additive and preparation method thereof

Abstract

The invention provides a high-strength tear-resistant rubber auxiliary agent which is characterized by comprising the following components in parts by weight: 5-15 parts of nano-scale filler, 3-10 parts of micron-scale short fibers with the diameter of 7-10 mu m and the length of 80-150 mu m, 1-3 parts of dispersion modifier, 0.5-5 parts of secondary crosslinking monomer, and a vulcanization system based on 100 parts by weight of a rubber matrix, the vulcanization system comprises 1-3 parts of sulfur, 0.5-2 parts of an accelerant, 3-5 parts of zinc oxide and 1-3 parts of stearic acid, crack propagation is effectively inhibited by adopting a multi-scale reinforcing structure, the tear strength of the rubber is remarkably improved, the tensile strength of the rubber is improved and the fatigue life of the rubber is prolonged by combining primary cross-linking treatment with secondary cross-linking reaction treatment, and the service life of the rubber is prolonged. Through precise control of rotor direction switching, uniform dispersion of the filler and fiber protection are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of rubber materials, and more specifically, to a rubber additive with high strength and tear resistance and a preparation method thereof. Background Art

[0002] There is a huge demand for high-performance rubber products in fields such as automotive tires, aerospace, and industrial seals. Traditional rubber reinforcement technologies mainly rely on carbon black or single nano-fillers (such as nano-silica, graphene oxide, etc.).

[0003] The closest existing technology, patent number: CN105482201A, a high-performance tire containing graphene oxide, the basic composition of the tread rubber consists of the following raw materials in parts by mass: matrix rubber 80 - 100 parts, highly dispersed silica 50 - 70 parts, silane coupling agent 4 - 6 parts, carbon black 5 - 10 parts, graphene oxide masterbatch 0 - 10 parts, plasticizer 2 - 8 parts, activator 1 - 3 parts, antioxidant 1 - 3 parts, vulcanization accelerator 1 - 3 parts, ordinary sulfur 1 - 2 parts, scorch retarder 0 - 0.3 parts. The graphene oxide masterbatch is a composite of graphene oxide and natural rubber, and the mass fraction of graphene oxide in the masterbatch is 5% - 15%.

[0004] Existing rubbers use carbon black and graphene oxide for reinforcement, but still have the following defects:

[0005] 1. Insufficient tear resistance: Single fillers are difficult to effectively prevent crack propagation, and the improvement of tear strength is limited.

[0006] 2. Uneven dispersion: Nano-fillers are prone to agglomeration, resulting in stress concentration and affecting the mechanical uniformity of the rubber.

[0007] 3. Weak interfacial bonding: The interfacial bonding force between the filler and the rubber matrix is weak, affecting the overall durability of the material.

[0008] In view of this, the present invention provides a rubber additive with high tensile strength, high fatigue life, high strength and tear resistance, and a preparation method thereof. Summary of the Invention

[0009] The object of the present invention is to provide a rubber additive with high tensile strength, high fatigue life, high strength and tear resistance, and a preparation method thereof.

[0010] A rubber additive with high strength and tear resistance, characterized in that it comprises the following components, based on 100 parts by weight of the rubber matrix:

[0011] Nano-scale filler 5 - 15 parts,

[0012] 3 - 10 parts of micro - scale short fibers, wherein the diameter of the micro - scale short fibers is 7 - 10 μm and the length is 80 - 150 μm

[0013] Fibers that are too thin (less than 5 μm) are not easily dispersed in rubber and tend to form agglomeration phenomena. Fibers that are too thick (greater than 15 μm) are prone to breakage during the processing, affecting the uniformity and processing performance of the rubber. Therefore, a better three - dimensional network structure is provided in the diameter range of 7 - 10 μm, effectively preventing crack propagation and effectively dispersing stress under repeated stress, delaying crack generation.

[0014] Fibers that are too short (less than 50 μm) are unevenly distributed in the matrix, and fibers that are too long (greater than 200 μm) increase the mixing and processing difficulty. Therefore, a three - dimensional network structure is effectively formed in the length range of 80 - 150 μm to ensure the reinforcement effect and prevent the rubber from generating too much stress concentration or fiber breakage problems during processing.

[0015] 1 - 3 parts of dispersion modifier

[0016] 0.5 - 5 parts of secondary cross - linking monomer

[0017] Vulcanization system, which includes 1 - 3 parts of sulfur, 0.5 - 2 parts of accelerator, 3 - 5 parts of zinc oxide, and 1 - 3 parts of stearic acid.

[0018] In some embodiments, the nano - scale filler is modified nano - silica or modified graphene oxide. The modified nano - silica is nano - silica modified by a silane coupling agent, and the modified graphene oxide is graphene oxide modified by a silane coupling agent.

[0019] In some embodiments, the particle size of the modified nano - silica is 20 - 50 nm, and the sheet thickness of the modified graphene oxide is less than 5 nm.

[0020] In some embodiments, the silane coupling agent is KH550 or KH570.

[0021] In some embodiments, the micro - scale short fibers are aramid fibers or carbon fibers or a mixture of aramid fibers and carbon fibers with their surfaces impregnated with epoxy resin or polyurethane. The aramid fibers and carbon fibers are modified by an epoxy resin emulsion or a polyurethane prepolymer to enhance the interfacial bonding force between the fibers and the rubber matrix, ensuring their effective dispersion in the rubber matrix and preventing the fibers from easily falling off.

[0022] Furthermore, the micro - scale short fibers are a mixture of aramid fibers and carbon fibers, and the mass ratio is 1:1 to 3:1, preferably 1:1.5, to enhance the anti - tear and anti - fatigue effects.

[0023] In some embodiments, the secondary crosslinking monomer is trimethylol acrylate or liquid nitrile rubber, and the addition amount is 1-2 parts.

[0024] In some embodiments, the dispersion modifier is a TDI prepolymer containing isocyanate groups or maleic anhydride grafted polyethylene.

[0025] Furthermore, the TDI prepolymer containing isocyanate groups is toluene diisocyanate, the NCO content in toluene diisocyanate is 5-10%, and the grafting rate of the maleic anhydride grafted polyethylene is 1-3%.

[0026] A method for preparing rubber using a high-strength tear-resistant rubber additive, characterized in that the method comprises the following steps:

[0027] Step 1: Pretreat the filler and micro-scale short fibers. The filler and micro-scale short fibers are pretreated separately. After the filler is pretreated, a modified mixture A is formed. The mixture A is composed of modified nano-silica / modified graphene oxide and a silane coupling agent. Through the modification of the silane coupling agent, after the micro-scale short fibers are pretreated, a mixture B is formed. The mixture B is composed of micro-scale short fibers and a fiber modifier.

[0028] Step 2: Uniformly mix the obtained mixture A with 100 parts of the rubber matrix. Mix the rubber matrix and the mixture A. The rotational speed of the internal mixer is 40 rpm, and the temperature is 120 °C to ensure that the filler is uniformly dispersed in the rubber matrix and avoid stress concentration caused by filler agglomeration. This step mainly makes the nano-scale filler and the rubber matrix uniformly mixed.

[0029] Step 3: Add the micro-scale short fibers. After the filler and the rubber matrix are uniformly mixed in Step 2, add the mixture B pretreated in Step 1 to the internal mixer in 3 portions to obtain the masterbatch. The rotational speed of the internal mixer is 40 rpm, the temperature is 120 °C, and the mixing time is 3 minutes. Add it in 3 portions, and mix for 1 minute after each addition.

[0030] Among them, in Step 1, a rubber-philic chemical layer will be formed on the surface of the silica, which can improve the bonding force between the silica and the rubber matrix and enhance the mechanical properties of the rubber. After the short fibers are modified by a fiber modifier (such as epoxy resin or polyurethane), a chemical modification layer will also be formed between the short fibers and the rubber matrix, enhancing the bonding force between the fiber and the rubber matrix and improving the tear resistance and fatigue resistance. In Step 3, the chemical bonding layer formed between the mixture A, the mixture B and the rubber matrix enhances their compatibility and dispersibility through surface modification, significantly improving the performance of the rubber.

[0031] Step 4: Vulcanization pretreatment. Transfer the pre-mixed masterbatch into an open mill, add the vulcanization system and the secondary crosslinking monomer. The rotational speed of the open mill is 20 rpm, the temperature is 80 °C, and the time is 2 minutes to ensure the uniform distribution of the vulcanization system and the crosslinking monomer, preparing for the subsequent vulcanization reaction and ensuring the crosslinkability of the rubber compound.

[0032] Step 5: Primary crosslinking treatment. Put the rubber compound mixed in Step 4 into a mold for vulcanization treatment. Among them, the pressure is 10 MPa. Starting from 120 °C, the temperature gradually increases at a speed of 1 - 2 °C per minute and finally reaches 155 °C in 30 minutes. Gradually increasing the temperature ensures the uniform progress of the reaction, and it is maintained at 155 °C for 20 minutes. This 20-minute period is the vulcanization time. Through the vulcanization treatment, a main crosslinking structure is formed, providing the basic mechanical properties of the rubber, ensuring the shape stability and durability of the rubber.

[0033] Step 6: Secondary crosslinking treatment. Subject the vulcanized material in Step 5 to heat treatment or ultraviolet irradiation to trigger secondary crosslinking to obtain the finished rubber. When it is heat treatment, the temperature is 120 °C and the time is 30 minutes. When it is ultraviolet irradiation, the light wavelength is 365 nm and the light intensity is 50 mW / cm 2 , and the irradiation time is 10 minutes to trigger the crosslinking reaction, forming a denser crosslinking network and improving heat resistance, fatigue resistance, and aging resistance.

[0034] Furthermore, in Step 3, the micron-sized short fibers are added in 3 times. When adding the micron-sized short fibers for the first time, 1 / 3 of the total amount of micron-sized short fibers is added. The rotational speed of the internal mixer is 40 rpm, the temperature is 120 °C, and the mixing time is 1 minute to ensure that the first addition of micron-sized short fibers is evenly dispersed in the rubber compound and avoid agglomeration. When adding the micron-sized short fibers for the second time, 1 / 3 of the total amount of micron-sized short fibers is added. The rotational speed of the internal mixer is 40 rpm, the temperature is 120 °C, and the mixing time is 1 minute. Based on the first addition and mixing of micron-sized short fibers, the fibers are further evenly distributed to ensure more uniform subsequent mixing. When adding the micron-sized short fibers for the third time, 1 / 3 of the total amount of micron-sized short fibers is added. The rotational speed of the internal mixer is 40 rpm, the temperature is 120 °C, and the mixing time is 1 minute to completely disperse the micron-sized short fibers and ensure the full combination of the fibers and the rubber matrix.

[0035] Furthermore, after each addition of micron-sized short fibers, the rotor direction needs to be switched, alternating between clockwise and counterclockwise directions to ensure that the micron-sized short fibers can be evenly distributed in the rubber compound and avoid oriented arrangement.

[0036] In some embodiments, in step six, the heat treatment is specifically as follows: the vulcanized material is placed in a heating device with temperature control function, and the vulcanized rubber product is placed flat on a tray or bracket in the heating device, ensuring that the contact between the rubber sample and the tray or bracket does not affect the flow of hot air. Then, it is gradually heated from room temperature to 120 °C to ensure uniform cross-linking reaction. When the temperature reaches 120 °C, it is kept at a constant temperature of 120 °C for 30 minutes. After heating, it is cooled down, and the heat-treated material is placed at room temperature for cooling. The cooling process continues until the surface and internal temperatures of the material completely drop to room temperature.

[0037] Furthermore, when the temperature rises from room temperature to 120 °C, the heating rate is 2 - 5 °C per minute to avoid rapid heating, preventing local overheating from affecting the material properties.

[0038] In some embodiments, the rubber matrix is natural rubber, styrene-butadiene rubber, cis-1,4-polybutadiene rubber or their blends.

[0039] In some embodiments, the vulcanization accelerator is sulfenamide or thiazole.

[0040] The present invention has the following beneficial effects:

[0041] 1. High tear strength: By adopting a multi-scale reinforcement structure effect, the crack propagation is inhibited, significantly improving the tear strength of the rubber. Specifically, the multi-scale reinforcement structure is that nano-fillers and micro-scale short fibers (such as modified nano-SiO 2 or graphene oxide) are uniformly dispersed in the rubber matrix, filling the voids between molecular chains and inhibiting crack propagation, thereby improving tear resistance and tensile strength. The micro-scale short fibers (such as aramid fibers or carbon fibers) are three-dimensionally interlaced to prevent cracks from propagating linearly, playing a bridging role and significantly improving tear resistance and fatigue life.

[0042] 2. High tensile strength and fatigue resistance: Through the combination of primary cross-linking treatment and secondary cross-linking reaction treatment, the tensile strength and fatigue life of the rubber are improved. Specifically, the primary cross-linking treatment network provides basic mechanical properties, and the secondary cross-linking network is triggered by heat treatment or ultraviolet light irradiation to form a dense cross-linking network, improving the heat resistance, wear resistance and fatigue resistance of the rubber. At the same time, during the secondary cross-linking structure, gradient heating is carried out to avoid local over-reaction.

[0043] 3. Facilitating filler dispersion and interfacial bonding with the rubber matrix: Through precise control of the rotor direction switching, uniform dispersion of the filler and fiber protection are achieved. Specifically, the rotor direction alternates between clockwise and counterclockwise directions to ensure that the micro-scale short fibers can be evenly distributed in the rubber compound, avoiding directional arrangement, and adding the short fibers in multiple times to ensure that the short fibers can be evenly distributed in the rubber compound. Description of the Drawings

[0044] Figure 1 It is a flowchart of the preparation method of the high-strength and tear-resistant rubber additive of the present invention.

[0045] Figure 2 It is an electron micrograph of the rubber products of Examples 1-3.

[0046] Figure 3 It is a partial electron micrograph of the rubber products of Examples 1-3.

[0047] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. Specific Embodiments

[0048] Example 1:

[0049] As Figure 1 shown, it is a flowchart of the preparation method of the high-strength and tear-resistant rubber additive of the present invention; as Figure 2 shown, it is an electron micrograph of the rubber products of Examples 1-3; as Figure 3 shown, it is a partial electron micrograph of the rubber products of Examples 1-3.

[0050] 100 parts of natural rubber,

[0051] 8 parts of modified nano-silica,

[0052] 5 parts of aramid fiber with a 100-μm surface impregnated with epoxy resin,

[0053] 2 parts of dispersion modifier, and the dispersion modifier is a TDI prepolymer containing an isocyanate group, and the TDI prepolymer containing an isocyanate group is toluene diisocyanate;

[0054] 1 part of secondary cross-linking monomer, and the secondary cross-linking monomer is trimethylolpropane triacrylate (TMPTA);

[0055] Vulcanization system, and the vulcanization system includes 2.5 parts of sulfur, 1 part of accelerator CZ, 3 parts of zinc oxide, and 2 parts of stearic acid.

[0056] A method for preparing rubber using a high-strength and tear-resistant rubber additive, comprising the following steps:

[0057] Step 1: Pretreat the filler and micron-sized short fibers. The nano-silica is modified with a silane coupling agent KH-550 and dried at 120 °C for 2 hours to form a mixture A (modified nano-silica),

[0058] The aramid fiber is impregnated in an epoxy resin emulsion, dried at 80 °C for 2 hours until the fiber is completely dry, and then cured at 100 °C for 2 hours to form a mixture B (modified aramid fiber);

[0059] Step 2: The obtained mixture A is uniformly mixed with 100 parts of natural rubber. The 100 parts of natural rubber and mixture A are kneaded. The mixture A and 100 parts of natural rubber are kneaded in a Banbury mixer. The speed of the Banbury mixer is 40 rpm, the rotor direction is clockwise, the temperature is 120 °C, and the time is 3 minutes.

[0060] Step 3: Add short fibers. After the filler and natural rubber are uniformly mixed in Step 2, the pretreated mixture B from Step 1 is added to the Banbury mixer in 3 portions to obtain a masterbatch. The speed of the Banbury mixer is 40 rpm, the temperature is 120 °C, and the kneading time is 3 minutes. It is added in 3 portions, and short fibers are added in 3 portions. When adding short fibers for the first time, 1 / 3 of the total amount of short fibers is added. The speed of the Banbury mixer is 40 rpm, the temperature is 120 °C, and the kneading time is 1 minute to ensure that the first addition of short fibers is uniformly dispersed in the rubber compound to avoid agglomeration. When adding short fibers for the second time, 1 / 3 of the total amount of short fibers is added. The speed of the Banbury mixer is 40 rpm, the temperature is 120 °C, and the kneading time is 1 minute. On the basis of the first addition of short fibers and mixing, the fibers are further evenly distributed to ensure more uniform subsequent mixing. When adding short fibers for the third time, 1 / 3 of the total amount of short fibers is added. The speed of the Banbury mixer is 40 rpm, the temperature is 120 °C, and the kneading time is 1 minute to make the short fibers completely dispersed and ensure full combination of the fibers and natural rubber. After each addition of short fibers, the rotor direction needs to be switched, alternating between clockwise and counterclockwise directions to ensure that the short fibers can be evenly distributed in the rubber compound and avoid oriented arrangement.

[0061] Step 4: Vulcanization pretreatment. The kneaded masterbatch is transferred to an open mill, and a vulcanization system and a secondary crosslinking monomer are added. The speed of the open mill is 20 rpm, the temperature is 80 °C, and the time is 2 minutes.

[0062] Step 5: Mold vulcanization. The kneaded rubber compound from Step 4 is put into a mold for vulcanization treatment. 2.5 parts of sulfur, 1 part of accelerator CZ, 3 parts of zinc oxide, and 2 parts of stearic acid are used. Among them, the pressure is 10 MPa. Starting from 120 °C, the temperature is gradually increased at a rate of 1 - 2 °C per minute, and finally reaches 155 °C in 30 minutes. The temperature is gradually increased to ensure uniform reaction, and it is maintained at 155 °C for 20 minutes. This 20 - minute period is the vulcanization time. Through vulcanization treatment, a main cross - linked structure is formed to provide the basic mechanical properties of the rubber and ensure the shape stability and durability of the rubber.

[0063] Step 6: Secondary crosslinking treatment. Heat-treat the vulcanized material in Step 5. When it is heat-treated, the temperature is 120°C and the time is 30 minutes. Specifically, place the vulcanized material into a heating device with temperature control function, and place the vulcanized rubber product flatly on the tray or bracket inside the heating device, ensuring that the contact between the rubber sample and the tray or bracket will not affect the hot air flow. Then heat from room temperature to 120°C. When the temperature reaches 120°C, maintain a constant temperature of 120°C for 30 minutes. After heating, cool down, and place the heat-treated material at room temperature for cooling. The cooling process continues until the surface and internal temperatures of the material completely drop to room temperature.

[0064] When the temperature rises from room temperature to 120°C, the heating rate is 2 - 5°C / minute to avoid too fast heating to prevent local overheating from affecting the material properties.

[0065] Detection method:

[0066] Tensile strength test: Use ASTM D412 standard to measure the maximum tensile strength of the finished product through a tensile testing machine.

[0067] Tear strength test: Use ASTM D624 standard to measure the tear strength of the sample.

[0068] Obtain Table 1

[0069] Performance indicators Example 1 Control group Tear strength (Kn / m) 105 72 Tensile strength (MPa) 23.7 18.2

[0070] It can be obtained from Table 1 that for the combination of natural rubber, modified silica, and modified aramid fiber, the tear strength is increased by about 46%, and the tensile strength is increased by about 30%.

[0071] Example 2:

[0072] As Figure 1 shown, it is the flowchart of the preparation method of the high-strength tear-resistant rubber additive of the present invention; as Figure 2 shown, it is the electron micrograph of the rubber finished products of Examples 1 - 3; as Figure 3 shown, it is the partial electron micrograph of the rubber finished products of Examples 1 - 3.

[0073] 100 parts of styrene-butadiene rubber,

[0074] 8 parts of modified nano-silica,

[0075] 5 parts of carbon fiber with 150μm surface polyurethane prepolymer,

[0076] 2 parts of dispersion modifier, and the dispersion modifier is a TDI prepolymer containing isocyanate group, and the TDI prepolymer containing isocyanate group is toluene diisocyanate;

[0077] 1.5 parts of the secondary crosslinking monomer, and the secondary crosslinking monomer is trimethylolpropane triacrylate (TMPTA);

[0078] Vulcanization system, the vulcanization system includes 2.5 parts of sulfur, 1 part of accelerator CZ, 3 parts of zinc oxide, and 2 parts of stearic acid.

[0079] A method for preparing rubber using a high-strength tear-resistant rubber aid, comprising the following steps:

[0080] Step 1: Pretreat the filler and micron-sized short fibers. The nano-silica is modified by the silane coupling agent KH-550 and dried at 120 °C for 2 hours to form a mixture A (modified nano-silica).

[0081] The carbon fiber is impregnated in the polyurethane prepolymer, the modification temperature is 80 °C, and it is cured for 1 hour to form a mixture B (modified carbon fiber).

[0082] Step 2: The obtained mixture A is uniformly mixed with 100 parts of styrene-butadiene rubber. The 100 parts of styrene-butadiene rubber and the mixture A are kneaded. The mixture A and 100 parts of styrene-butadiene rubber are kneaded in a mixer. The mixer speed is 40 rpm, the rotor direction is clockwise, the temperature is 120 °C, and the time is 3 minutes.

[0083] Step 3: Add short fibers. After the filler and styrene-butadiene rubber are uniformly mixed in Step 2, the mixture B pretreated in Step 1 is added to the mixer in 3 portions to obtain a masterbatch. The mixer speed is 40 rpm, the temperature is 120 °C, and the kneading time is 3 minutes. Add the short fibers in 3 portions. When adding the short fibers for the first time, add 1 / 3 of the total amount of short fibers. The mixer speed is 40 rpm, the temperature is 120 °C, and the kneading time is 1 minute to ensure that the short fibers are uniformly dispersed in the rubber compound to avoid agglomeration. When adding the short fibers for the second time, add 1 / 3 of the total amount of short fibers. The mixer speed is 40 rpm, the temperature is 120 °C, and the kneading time is 1 minute. On the basis of the first addition of short fibers and mixing, continue to evenly distribute the fibers to ensure more uniform subsequent mixing. When adding the short fibers for the third time, add 1 / 3 of the total amount of short fibers. The mixer speed is 40 rpm, the temperature is 120 °C, and the kneading time is 1 minute to make the short fibers completely dispersed and ensure that the fibers are fully combined with the styrene-butadiene rubber. After each addition of short fibers, the rotor direction needs to be switched, alternating between clockwise and counterclockwise directions to ensure that the short fibers can be evenly distributed in the rubber compound and avoid oriented arrangement.

[0084] Step 4: Vulcanization pretreatment. Transfer the kneaded masterbatch to an open mill, add the vulcanization system and the secondary crosslinking monomer. The open mill speed is 20 rpm, the temperature is 80 °C, and the time is 2 minutes.

[0085] Step 5: Compression molding and vulcanization. Put the kneaded rubber compound in Step 4 into a mold for vulcanization treatment. The ingredients are 2.5 parts of sulfur, 0.5 - 2 parts of accelerator CZ, 3 parts of zinc oxide, and 2 parts of stearic acid. Among them, the pressure is 10 MPa. Starting from 120 °C, the temperature gradually rises at a rate of 1 - 2 °C per minute and finally reaches 155 °C in 30 minutes. Gradually increasing the temperature ensures uniform reaction. And keep the temperature at 155 °C for 20 minutes. This 20 - minute period is the vulcanization time. Through vulcanization treatment, a main cross - linked structure is formed, providing the basic mechanical properties of the rubber, ensuring the shape stability and durability of the rubber.

[0086] Step 6: Secondary cross - linking treatment. Heat - treat the vulcanized material in Step 5. When it is heat - treated, the temperature is 120 °C and the time is 30 minutes. Specifically, put the vulcanized material into a heating device with temperature control function. Place the vulcanized rubber product flat on a tray or bracket inside the heating device, ensuring that the contact between the rubber sample and the tray or bracket does not affect the flow of hot air. Then heat from room temperature to 120 °C. When the temperature reaches 120 °C, keep it at a constant temperature of 120 °C for 30 minutes. After heating, cool down. Place the heat - treated material at room temperature to cool, and the cooling process continues until the surface and internal temperatures of the material completely drop to room temperature.

[0087] When the temperature rises from room temperature to 120 °C, the heating rate is 2 - 5 °C / minute, avoiding too fast heating to prevent local overheating from affecting the material properties.

[0088] Testing method:

[0089] Tensile strength test: Use the ASTM D412 standard and measure the maximum tensile strength of the finished product through a tensile testing machine.

[0090] Tear strength test: Use the ASTM D624 standard to measure the tear strength of the sample.

[0091] Obtain Table 2:

[0092] Performance indicators Example 2 Control group Tear strength (Kn / m) 120 72 Tensile strength (MPa) 18.3 18.2

[0093] It can be obtained from Table 2 that for the combination of styrene - butadiene rubber, modified silica, and modified carbon fiber, the tear strength is increased by about 66.67 and the tensile strength is increased by about 37.24%.

[0094] Example 3:

[0095] As Figure 1 shown, it is the flowchart of the preparation method of the high - strength tear - resistant rubber additive of the present invention; as Figure 2 shown, it is the electron micrograph of the rubber finished products of Examples 1 - 3; as Figure 3 shown, it is the partial electron micrograph of the rubber finished products of Examples 1 - 3.

[0096] 100 parts of styrene-butadiene rubber,

[0097] 6 parts of modified graphene oxide,

[0098] 4 parts of aramid fiber with a surface impregnated with epoxy resin of 100 μm

[0099] 3 parts of carbon fiber with a surface impregnated with epoxy resin of 150 μm,

[0100] 2 parts of dispersion modifier, the dispersion modifier is a TDI prepolymer containing an isocyanate group, and the TDI prepolymer containing an isocyanate group is toluene diisocyanate;

[0101] 1.5 parts of secondary cross-linking monomer, and the secondary cross-linking monomer is trimethylolpropane triacrylate (TMPTA);

[0102] Vulcanization system, the vulcanization system includes 2.5 parts of sulfur, 1 part of accelerator CZ, 3 parts of zinc oxide, and 2 parts of stearic acid.

[0103] A method for preparing rubber using a high-strength and tear-resistant rubber aid, comprising the following steps:

[0104] Step 1: Pretreat the filler and micro-scale short fibers. Nano-graphene oxide is modified by silane coupling agent KH-550 and treated at 120 °C for 2 hours to form mixture A (modified graphene oxide),

[0105] Aramid fiber and carbon fiber are impregnated in a polyurethane prepolymer, the modification temperature is 80 °C, and it is cured for 1 hour to form mixture B (modified aramid fiber and carbon fiber mixture);

[0106] Step 2: The obtained mixture A is uniformly mixed with 100 parts of styrene-butadiene rubber. 100 parts of styrene-butadiene rubber and mixture A are kneaded. Mixture A and 100 parts of styrene-butadiene rubber are kneaded in a mixer. The mixer speed is 40 rpm, the rotor direction is clockwise, the temperature is 120 °C, and the time is 3 minutes;

[0107] Step 3: Adding short fibers. After the filler and styrene-butadiene rubber are evenly mixed in Step 2, the mixture B pretreated in Step 1 is added to the internal mixer in 3 portions to obtain the masterbatch. The rotational speed of the internal mixer is 40 rpm, the temperature is 120 °C, and the mixing time is 3 minutes. The short fibers are added in 3 portions. When adding the short fibers for the first time, 1 / 3 of the total amount of short fibers is added. The rotational speed of the internal mixer is 40 rpm, the temperature is 120 °C, and the mixing time is 1 minute to ensure that the short fibers are evenly dispersed in the rubber compound and avoid agglomeration. When adding the short fibers for the second time, 1 / 3 of the total amount of short fibers is added. The rotational speed of the internal mixer is 40 rpm, the temperature is 120 °C, and the mixing time is 1 minute to continue to evenly distribute the fibers on the basis of the first addition of short fibers and ensure more uniform subsequent mixing. When adding the short fibers for the third time, 1 / 3 of the total amount of short fibers is added. The rotational speed of the internal mixer is 40 rpm, the temperature is 120 °C, and the mixing time is 1 minute to completely disperse the short fibers and ensure full combination of the fibers and styrene-butadiene rubber. After each addition of short fibers, the rotor direction needs to be switched, alternating between clockwise and counterclockwise directions to ensure that the short fibers can be evenly distributed in the rubber compound and avoid oriented arrangement.

[0108] Step 4: Vulcanization pretreatment. The kneaded masterbatch is transferred to a two-roll mill, and a vulcanization system and a secondary crosslinking monomer are added. The rotational speed of the two-roll mill is 20 rpm, the temperature is 80 °C, and the time is 2 minutes.

[0109] Step 5: Mold pressing and vulcanization. The rubber compound kneaded in Step 4 is put into a mold for vulcanization treatment. 2.5 parts of sulfur, 0.5 - 2 parts of accelerator CZ, 3 parts of zinc oxide, and 2 parts of stearic acid are used. Among them, the pressure is 10 MPa. Starting from 120 °C, the temperature gradually rises at a rate of 1 - 2 °C per minute and finally reaches 155 °C in 30 minutes. The temperature is gradually increased to ensure uniform reaction, and it is maintained at 155 °C for 20 minutes. This 20-minute period is the vulcanization time. Through vulcanization treatment, a main crosslinking structure is formed to provide the basic mechanical properties of the rubber and ensure the shape stability and durability of the rubber.

[0110] Step 6: Secondary crosslinking treatment. The vulcanized material in Step 5 is heat-treated. When heat-treating, the temperature is 120 °C and the time is 30 minutes. Specifically, the vulcanized material is placed in a heating device with temperature control function. The vulcanized rubber product is placed flat on a tray or bracket in the heating device to ensure that the contact between the rubber sample and the tray or bracket does not affect the flow of hot air. Then it is heated from room temperature to 120 °C. When the temperature reaches 120 °C, it is kept at a constant temperature of 120 °C for 30 minutes. After heating, it is cooled down, and the heat-treated material is placed at room temperature for cooling. The cooling process continues until the surface and internal temperatures of the material completely drop to room temperature.

[0111] When the temperature rises from room temperature to 120 °C, the heating rate is 2-5 °C per minute to avoid rapid heating to prevent local overheating from affecting the material properties.

[0112] Detection method:

[0113] Tensile strength test: Using the ASTM D412 standard, the maximum tensile strength of the finished product is measured by a tensile testing machine.

[0114] Tear strength test: Using the ASTM D624 standard, the tear strength of the sample is measured.

[0115] Table 3 is obtained:

[0116]

[0117]

[0118] It can be obtained from Table 3 that for the combination of styrene-butadiene rubber and the mixture of modified graphene and modified aramid fiber and carbon fiber, the tear strength is increased by about 73.61% and the tensile strength is increased by about 40.54%.

[0119] The above-described embodiments merely represent several implementation manners of the present invention, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the appended claims.

Claims

1. A high-strength tear-resistant rubber additive, characterized in that: The composition comprises the following components, based on 100 parts by weight of the rubber matrix: 5-15 parts of nano-scale filler, 3-10 parts of micron-sized short fibers, wherein the micron-sized short fibers have a diameter of 7-10 μm and a length of 80-150 μm, and 1-3 parts of a dispersing modifier, Secondary crosslinking monomer 0.5-5 parts, The vulcanization system includes 1-3 parts of sulfur, 0.5-2 parts of accelerator, 3-5 parts of zinc oxide and 1-3 parts of stearic acid.

2. The high-strength tear-resistant rubber additive according to claim 1, characterized in that: The nanoscale filler is modified nano-silicon dioxide or modified graphene oxide. The modified nano-silicon dioxide is nano-silicon dioxide modified by a silane coupling agent, and the modified graphene oxide is graphene oxide modified by a silane coupling agent.

3. The high-strength tear-resistant rubber additive according to claim 1, characterized in that: The silane coupling agent is KH550 or KH570.

4. The high-strength tear-resistant rubber additive according to claim 1, characterized in that: The micron-sized short fibers are aramid fibers or carbon fibers or a mixture of aramid fibers and carbon fibers, the surfaces of which are impregnated with epoxy resin or polyurethane. The aramid fibers and carbon fibers are modified with epoxy resin emulsion or polyurethane prepolymer.

5. The high-strength tear-resistant rubber additive according to claim 1, characterized in that: The secondary cross-linking monomer is trimethylolacrylate or liquid nitrile rubber, and the added amount is 1-2 parts.

6. The high-strength tear-resistant rubber additive according to claim 1, characterized in that: The dispersion modifier is TDI prepolymer containing isocyanate group or maleic anhydride grafted polyethylene.

7. The method for preparing rubber using a high-strength tear-resistant rubber additive according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: Step 1: pretreating fillers and micron-sized short fibers. The fillers and micron-sized short fibers are pretreated separately. After the fillers are pretreated, a modified mixture A is formed. The mixture A is composed of modified nano-silicon dioxide / modified graphene oxide and a silane coupling agent. The micron-sized short fibers are pretreated by the silane coupling agent to form a mixture B. The mixture B is composed of micron-sized short fibers and a fiber modifier. Step 2: uniformly mix the obtained mixture A with 100 parts of the rubber matrix, and knead the rubber matrix and the mixture A; Step 3: Add micron-sized short fibers. After the filler and the rubber matrix are evenly mixed in step 2, add the mixture B pretreated in step 1 into the internal mixer three times to obtain a masterbatch. The internal mixer speed is 40 rpm, the temperature is 120°C, the mixing time is 3 minutes, and the mixture is added three times. Mix for 1 minute after each addition. Step 4: Vulcanization pretreatment, transfer the mixed masterbatch into the open mixer, add the vulcanization system and secondary crosslinking monomer; Step 5: Primary cross-linking treatment, placing the rubber compound mixed in step 4 into a mold for vulcanization treatment; Step 6: Secondary cross-linking treatment, heat treatment or ultraviolet irradiation of the vulcanized material in step 5 to trigger secondary cross-linking to obtain the finished rubber.

8. The method for preparing the high-strength tear-resistant rubber additive according to claim 7, characterized in that: In step three, the micron-sized staple fibers are added in three times. When the micron-sized staple fibers are added for the first time, 1 / 3 of the total amount of micron-sized staple fibers is added, the speed of the internal mixer is 40 rpm, the temperature is 120°C, and the mixing time is 1 minute. This ensures that the micron-sized staple fibers are evenly dispersed in the rubber compound to avoid agglomeration. When the micron-sized staple fibers are added for the second time, 1 / 3 of the total amount of micron-sized staple fibers is added, the speed of the internal mixer is 40 rpm, the temperature is 120°C, and the mixing time is 1 minute. On the basis of the first mixing of the micron-sized staple fibers, the fibers are continued to be evenly distributed to ensure that the subsequent mixing is more uniform. When the micron-sized staple fibers are added for the third time, 1 / 3 of the total amount of micron-sized staple fibers is added, the speed of the internal mixer is 40 rpm, the temperature is 120°C, and the mixing time is 1 minute. This allows the micron-sized staple fibers to be completely dispersed, ensuring that the fibers are fully combined with the rubber matrix.

9. The method for preparing the high-strength tear-resistant rubber additive according to claim 8, characterized in that: Each time the micron-sized short fibers are added, the direction of the rotor needs to be switched, alternating between clockwise and counterclockwise directions, to ensure that the micron-sized short fibers can be evenly distributed in the rubber compound to avoid directional arrangement.

10. The method for preparing a high-strength tear-resistant rubber additive according to claim 7, characterized in that: In step six, the heat treatment is specifically as follows: placing the vulcanized material into a heating device with a temperature control function, placing the vulcanized rubber product flatly on a tray or bracket in the heating device, ensuring that the contact between the rubber sample and the tray or bracket does not affect the flow of hot air, and then gradually heating from room temperature to 120°C to ensure a uniform cross-linking reaction. When the temperature reaches 120°C, maintain a constant temperature of 120°C for 30 minutes. After heating is completed, cool down and place the heat-treated material at room temperature to cool. The cooling process continues until the surface and internal temperature of the material completely drops to room temperature.

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