Nitrile rubber composite material and preparation method thereof

Abstract

The nitrile rubber composite material comprises the following raw material components in parts by weight: 100 parts of nitrile rubber, 0.5-3 parts of stearic acid, 1.5-3.5 parts of nano-zinc oxide, 1-4 parts of an assistant vulcanizing agent or an accelerant, 2-6 parts of a vulcanizing agent, 15-30 parts of white carbon black, 20-80 parts of a carbon black reinforcing agent, a silane coupling agent with the dosage being 1-3% of the mass of the white carbon black, and 0.2-4 parts of an anti-aging agent. The content of combined acrylonitrile in the nitrile rubber is 29%-42%; the vulcanization system is a peroxide vulcanization system or a composite vulcanization system formed by mixing the peroxide vulcanization system and a sulfur vulcanization system. The invention also discloses a preparation method of the nitrile rubber composite material, which comprises the following steps: mixing the raw material components to form a rubber compound, and vulcanizing the rubber compound. The nitrile rubber composite material has the advantages of high resilience and low compression set performance under high hardness.

Description

Technical Field

[0001] This invention belongs to the field of composite material preparation technology, specifically relating to a nitrile rubber composite material, and also to a method for preparing the aforementioned nitrile rubber composite material. Background Technology

[0002] Nitrile rubber possesses excellent elasticity and chemical stability, making it widely used in the rubber hose manufacturing industry. In recent years, with the development of the industrial economy, China has placed higher demands on elastic materials suitable for sports equipment, automobiles, shock absorption, and medical applications. These materials not only require good mechanical properties but also high resilience and low compression set under high hardness.

[0003] Chinese patent CN102702588A, published on October 3, 2012, discloses a damping rubber material with low hardness, high-temperature static torque, and good durability, and its preparation method. Its composition, by weight parts, is: 100 parts of nitrile rubber and styrene-butadiene rubber composite material, 40-70 parts of reinforcing filler, 5-10 parts of nano-silica, 1-3 parts of coupling agent and processing aids, 10-15 parts of softening plasticizer, 2-3 parts of antioxidant, and 8-10 parts of vulcanizing and auxiliary agents. Nitrile rubber is a copolymer of butadiene and acrylonitrile, with an acrylonitrile content of 28-33%. The vulcanizing agent in the vulcanization process and auxiliaries is one of the following: organic peroxide DCP (dicumyl peroxide), odorless DCP (tert-butyl peroxide dicumylbenzene), or bis(2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), used in at least 2 parts. The vulcanization auxiliaries include accelerators and activators, with the accelerator being either TAIC or HVA-2, used in 1-2 parts by weight. The activators include the inorganic activator zinc oxide and the organic activator stearic acid, with zinc oxide at 4-6 parts and stearic acid at 1-2 parts. This technology yields a low-hardness, shock-absorbing rubber material.

[0004] Chinese Patent CN113402792A, published on September 17, 2021, discloses an IRM903 oil-based low-pressure modified nitrile butadiene rubber material and its preparation method. The rubber material includes 47-52 wt.% high Mooney nitrile butadiene raw rubber 3370C, 2-3 wt.% zinc oxide, 0.3-0.7 wt.% stearic acid, 0.8-1.2 wt.% antioxidant 4010NA, 0.4-0.6 wt.% antioxidant RD, 1.5-2.5 wt.% peroxide vulcanizing agent Perkadox 14 (RTM: di(tert-butylperoxyisopropyl)benzene), 1.5-2.5 wt.% peroxide crosslinking agent Chemmix PMA-201, 26-30 wt.% ST1120 carbon black, 9-12 wt.% N774 semi-reinforcing carbon black, and 2-5 wt.% plasticizer W260S. This technology overcomes the weakness of nitrile rubber in IRM903# oil, which has a large volume increase and high swelling, without the use of silica and coupling agents.

[0005] Chinese patent CN115806701A, published on March 17, 2023, discloses a high-hardness, wear-resistant, and durable hydrogenated nitrile butadiene rubber compound and its preparation method. The compound comprises the following raw materials in parts by weight: 80-100 parts of hydrogenated nitrile butadiene rubber, 4-7 parts of zinc oxide, 0.5-2 parts of stearic acid, 30-60 parts of carbon black, 0-15 parts of silica, 0-20 parts of filler, 1-3 parts of aniline antioxidant, 0-15 parts of processing aid, and 3-6 parts of peroxide vulcanizing agent. The filler is silicate, and the processing aids include saturated fatty acid esters and / or erucamide. No coupling agent is used, but the silica is surface-grafted with maleimide. Its preparation method includes: adding silica and N-(2-hydroxyethyl)maleimide to ethanol at a mass ratio of 12:1 and stirring until homogeneous; then adding 1 wt% dibutyltin dilaurate of silica; heating to 60°C and stirring for 4 hours; and finally evaporating the ethanol to obtain the surface-grafted maleimide silica. This technology uses hydrogenated nitrile butadiene rubber and surface-grafted maleimide silica, resulting in high raw material costs.

[0006] Chinese patent CN107573556A, published on January 12, 2018, discloses a sealing gasket rubber material for automotive oil pans and its preparation method. The rubber material contains 100 parts by weight of nitrile rubber, 6-8 parts by weight of zinc oxide, 1-2 parts by weight of stearic acid, 1-2 parts by weight of 2,2,4-trimethyl-1,2-dihydroquinoline polymer, 1-5 parts by weight of N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine, 80-95 parts by weight of spray-dried carbon black, 5-10 parts by weight of dioctyl phthalate, 1.5-2.5 parts by weight of dicumyl peroxide, 1-2 parts by weight of 2-mercaptobenzothiazole, 1-5 parts by weight of tetramethylthiuram disulfide, and 0.2-0.5 parts by weight of sulfur. Instead of using silica and coupling agents, sprayed carbon black is used to reduce the compression set of rubber. Diisopropylbenzene peroxide, tetramethylthiuram disulfide and sulfur are used in combination to simultaneously take into account the aging and strength properties of rubber materials. The compression set of the product is 18.2% (120℃×22h, 25%).

[0007] Chinese Patent CN111171409A, published on May 19, 2020, discloses a high-temperature resistant, high-strength, and high-expansion rubber and its preparation method, comprising the following components by weight: 100 parts of nitrile rubber, 0.5-2 parts of stearic acid, 10-20 parts of fumed silica, 3-5 parts of carbon nanotubes, 20-30 parts of carbon black N330, 1-2 parts of silane coupling agent, 3-8 parts of metal oxide, 1-3 parts of antioxidant, 0.7-0.9 parts of crosslinking agent, and 5-10 parts of co-crosslinking agent. The crosslinking agent is at least one selected from DCP (dicumyl peroxide), BIPB (di-tert-butyl peroxide), and bis(2,5-dimethyl-2,5-bis(tert-butyl peroxide)hexane); the co-crosslinking agent is an acrylate. Nitrile butadiene rubber (NBR) with high acrylonitrile content and high Mooney viscosity is preferred, such as NBR with an acrylonitrile content of over 40% and a Mooney viscosity of over 75. Carbon black N330 is added as a filler, and the addition of fumed silica and carbon nanotubes can reduce the amount of crosslinking agent to less than 1 part. Simultaneously, acrylates are used as a co-crosslinking agent, and a four-stage mixing and one-stage vulcanization method is employed to obtain rubber with high elongation at break, tensile strength, and high expansion rate at high temperatures.

[0008] Chinese Patent CN117844076A, published on April 9, 2024, discloses a low-pressure modified nitrile butadiene rubber compound and its preparation method. This low-pressure modified nitrile butadiene rubber compound is made from the following raw materials in parts by weight: 100 parts nitrile butadiene rubber, 5-10 parts zinc oxide, 1-3 parts stearic acid, 1-2 parts antioxidant RD, 1-1.5 parts antioxidant MB, 2-3 parts antioxidant 4010NA, 2-3 parts microcrystalline wax 9108, 95-120 parts carbon black, 20-30 parts inorganic filler, 20-22 parts plasticizer, 2-3 parts vulcanizing agent, 1-2 parts accelerator, 0.3-1 part scorching inhibitor, 1-3.5 parts adhesive RS, and 2-4 parts adhesive RA-65. It also does not use silica or coupling agents; the inorganic filler is kaolin; and the acrylonitrile (ACN) content in the nitrile butadiene rubber is 18-24%. This invention targets sulfur vulcanization systems by adding adhesives RS and RA-65. The adhesive RS and the methylene donor adhesive RA-65 undergo a resinification reaction, thereby increasing the crosslinking degree of nitrile rubber compounds under low-temperature vulcanization conditions and improving low-pressure deformation performance. Summary of the Invention

[0009] The first objective of this invention is to provide a nitrile rubber composite material that possesses the advantages of high resilience and low compression set under high hardness.

[0010] The second objective of this invention is to provide a method for preparing the above-mentioned low-pressure variable, high-resilience nitrile rubber composite material.

[0011] The first technical solution adopted in this invention is as follows: a nitrile rubber composite material, particularly a low-pressure deformation and high-resilience nitrile rubber composite material, which comprises the following raw material components by weight: 100 parts of nitrile rubber, 0.5-3 parts of stearic acid, 1.5-3.5 parts of nano zinc oxide, preferably 2-3 parts, 1-4 parts of vulcanizing agent or accelerator, 2-6 parts of vulcanizing agent, 15-30 parts of silica, preferably 15-20 parts, 20-80 parts of carbon black reinforcing agent, 1%-3% of silane coupling agent by weight of silica, and 0.2-4 parts of antioxidant; the bound acrylonitrile content of the nitrile rubber is 29%-42%, preferably 31%-35%; the vulcanization system is a peroxide vulcanization system or a composite vulcanization system using a mixture of peroxide vulcanization system and sulfur vulcanization system, preferably a composite vulcanization system using a mixture of peroxide vulcanization system and sulfur vulcanization system.

[0012] The second technical solution adopted in this invention is as follows: the preparation method of the above-mentioned nitrile rubber composite material involves mixing the raw material components to form a compound, and then subjecting the compound to vulcanization treatment.

[0013] More specifically and optimized, it is prepared according to the following steps: First stage of mixing: The internal mixer temperature is 50℃~60℃, the speed is 30~50r / min. Nitrile rubber is put into the internal mixer and plasticized for 2~8min. Silica, silane coupling agent, carbon black, zinc oxide, stearic acid and accelerator are added in proportion. The top bolster of the internal mixer is driven to provide mixing pressure to the mixing chamber. Mix for 3~9min to obtain a uniformly mixed masterbatch. Two-stage mixing: The masterbatch obtained from the first-stage mixing is recycled on a two-roll mill, and a vulcanizing agent is added. The mixture is then passed through a thin tube in a triangular shape 3 to 7 times. The roll gap is adjusted and the sheet is then sheeted to obtain the nitrile rubber compound. Vulcanization and setting: After the nitrile rubber compound obtained from the two-stage mixing is allowed to stand for 24h~36h, it is vulcanized in a flat vulcanizing machine at 175±10℃ and 15±5MPa to obtain the product.

[0014] The beneficial effects of this invention are: (1) The low-pressure deformation and high-resilience nitrile rubber composite material of the present invention uses nitrile rubber with medium to high acrylonitrile content as the main rubber, which reduces the crosslinking density of molecules and increases the gap between molecular chains. The nitrile rubber has low oil absorption and good oil resistance; it avoids the occurrence of rubber surface viscous flow caused by excessive acrylonitrile content, and has good material flowability and processability; it retains the high elastic modulus and high tensile strength of rubber and other mechanical properties, which can effectively ensure the high resilience and low compression set of the vulcanized rubber. (2) The low-pressure variable, high-resilience nitrile rubber composite material of the present invention adopts a composite reinforcement system. Carbon black has a large specific surface area and a highly crystalline carbon layer structure, which has an excellent reinforcement effect. Silica has an extremely low specific surface area and an amorphous carbon layer structure, which has excellent weather resistance and chemical stability, and can maintain the stability of the material under high temperature environment. Using carbon black and silica together is beneficial to improving the comprehensive properties of the rubber compound, such as mechanical properties and heat resistance stability. (3) The vulcanization system used in the low-pressure deformation and high-resilience nitrile rubber composite material of the present invention contains at least a peroxide vulcanization system. The reaction continuously forms -CC- bonds with high bond energy and high chemical stability. The prepared vulcanized rubber has low permanent deformation and good elasticity, and has excellent resistance to thermo-oxidative aging. More preferably, the peroxide vulcanization system and the sulfur vulcanization system are used in combination. Their synergistic effect is better, and the prepared vulcanized rubber has a moderate degree of crosslinking, high elasticity, and better compression set. Detailed Implementation

[0015] The present invention will now be described in detail with reference to specific embodiments. Unless otherwise specified (such as %) in the method testing standards, all parts referred to in the present invention are parts by weight, and % is a weight percentage.

[0016] The nitrile rubber composite material of the present invention comprises the following raw material components in parts by weight: 100 parts nitrile rubber, 0.5-3 parts stearic acid, 1.5-3.5 parts nano zinc oxide, 1-4 parts vulcanizing agent or accelerator, 2-6 parts vulcanizing agent, 15-30 parts silica, 20-80 parts carbon black reinforcing agent, 1%-3% of silane coupling agent by weight of silica, and 0.2-4 parts antioxidant. The vulcanizing agent, vulcanizing agent, and accelerator constitute the vulcanization system. The vulcanization system of the present invention is a peroxide vulcanization system or a composite vulcanization system using a mixture of a peroxide vulcanization system and a sulfur vulcanization system, preferably a composite vulcanization system using a mixture of a peroxide vulcanization system and a sulfur vulcanization system.

[0017] In the aforementioned low-pressure variable, high-resilience nitrile butadiene rubber composite material, the carbon black reinforcing agent can be any carbon black commonly used in the art, such as one or a mixture of carbon black N220, carbon black N550, and carbon black N774. The type and amount added can be adjusted according to the performance requirements of the product, and it is preferable to use two or more types of carbon black. Too little carbon black is not conducive to improving the mechanical properties and thermal stability of the rubber compound, while too much carbon black is difficult to disperse and is not conducive to the uniformity of the rubber compound. A more preferred amount is 60 to 70 parts.

[0018] In the composite material of this invention, not only carbon black reinforcing agent but also silica (white carbon black) is required as a reinforcing agent. The amount of silica added is 15-30 parts, preferably 15-20 parts. Generally, the amount of silica added should not exceed the amount of carbon black added.

[0019] In the aforementioned low-pressure variable, high-resilience nitrile rubber composite material, the zinc oxide is nano-zinc oxide, preferably with a particle size of 20-100 nm. Nano-zinc oxide has a small particle size and large specific surface area, resulting in a strong adsorption effect on accelerators. The addition of nano-zinc oxide delays the movement of rubber macromolecular chains, reducing the reactivity of macromolecular chains with the vulcanization system in this invention. This improves the stability of the compound, prevents scorching, and enhances high-temperature resistance and anti-aging properties. More preferably, the nano-zinc oxide is modified nano-zinc oxide. Modified nano-zinc oxide effectively prevents the re-agglomeration of nano-zinc oxide particles, which is beneficial for improving its dispersibility in the rubber compound. Examples include commercially available nano-zinc oxide with a particle size of 20-100 nm modified with coupling agent KH550. The amount of nano-zinc oxide added is 1.5-3.5 parts, preferably 2-3 parts, and the amount of modified nano-zinc oxide is more preferably 2-2.8 parts. In this invention, the amount of nano zinc oxide used is lower than that of ordinary zinc oxide in the prior art. With a relatively small amount of nano zinc oxide, the aging resistance of the rubber compound can be improved, the amount of antioxidant can be reduced, and common problems such as antioxidant failure at high temperature and precipitation due to mixing can be avoided. This comprehensively improves the vulcanization rate and crosslinking degree of the rubber compound, and the obtained nitrile rubber composite material has the effects of low compression set and high resilience.

[0020] The coupling agent used in the aforementioned low-pressure deformable, high-resilience nitrile rubber composite material is a silane coupling agent, which can be a commonly used silane coupling agent in the art. This invention does not have specific requirements; for example, it can be one of KH560, KH580, Si-69, etc. The addition of a silane coupling agent can effectively promote the dispersion of the reinforcing agent in the rubber matrix, effectively prevent the aggregation of the reinforcing agent during vulcanization, reduce the reinforcing agent network structure, enhance the instantaneous recovery and reconstruction ability of the vulcanized rubber network, and help reduce the compression set and improve the resilience of the vulcanized rubber. In this invention, the amount of silane coupling agent added is only 1% to 3% of the amount of silica used. Excessive addition of silane coupling agent is detrimental to the excellent performance of the nitrile rubber composite material of this invention.

[0021] The addition of stearic acid to the low-pressure variable, high-resilience nitrile rubber composite material of this invention also improves the solubility of nano-zinc oxide in the rubber. Together, they act as a vulcanization activation system, accelerating the vulcanization speed and increasing the crosslinking density of the rubber compound, effectively improving its hardness and tensile strength. The preferred amount of stearic acid is 1.2 to 3 parts.

[0022] The vulcanization system of this invention can employ a peroxide vulcanization system. Upon heating with rubber, it homogenizes to generate two alkoxy radicals, which then abstract active hydrogen atoms from the α-methylene group of the rubber molecular chain and combine with radicals from adjacent rubber molecular chains. This reaction continuously forms -CC- bonds with high bond energy and high chemical stability. More preferably, a mixture of the peroxide vulcanization system and the sulfur vulcanization system is used, as their synergistic effect is better, resulting in a vulcanized rubber with moderate crosslinking, high elasticity, and low compression set. The vulcanizing agent in the vulcanization system can be a peroxide vulcanizing agent or a mixture of a peroxide vulcanizing agent and sulfur.

[0023] Common peroxide vulcanizing agents include dialkyl peroxides, diacyl peroxides, and peroxide esters, with dicumyl peroxide (DCP) being the preferred choice. The vulcanizing aids commonly used in peroxide vulcanization systems are multifunctional monomers with polar free radical polymerization properties, such as one or more of N,N'-m-phenylenebismaleimide (HVA-2), zinc diacrylate (ZDAA), and zinc dimethacrylate (ZDMA). These vulcanizing aids can be homopolymerized or grafted onto the polymer chain, improving the crosslinking efficiency of the peroxide, accelerating the vulcanization speed, lowering the decomposition temperature of the peroxide, and maintaining the excellent properties of the vulcanized rubber. The preferred amount of peroxide vulcanizing agent added is 2-3 parts. The preferred amount of vulcanizing aid added is 1-3 parts.

[0024] Furthermore, the accelerator in the sulfur vulcanization system is not particularly required in this invention; any general accelerator will suffice, such as thiazoles or thiurams, preferably one or more of CZ (N-cyclohexyl-2-benzothiazole sulfenamide), DTDM (4,4′-dithiodimorpholine), and TMTD (tetramethylthiuram disulfide). In this invention, the preferred amount of sulfur added is 2-6 parts. By increasing the sulfur ratio, the vulcanized rubber generates a large number of polysulfide bonds and a small number of low-sulfide bonds (monosulfide and disulfide bonds), thereby increasing the tensile strength of the vulcanized rubber.

[0025] Because CZ contains two hydroxyl groups, when used in combination with thiuram-based accelerators DTDM or TMTD, it releases active sulfur or sulfur-containing free radicals, which react with rubber molecules. If XSSX represents the thiuram-based accelerator and RH represents the rubber molecule, then: XSSX→2XS·or XSS·+·X, XS·+RH→XSH+R·, XSS+RH→XSH+RS. R· + RS → RSR (monosulfur crosslinking). 2RS·→RSSR (disulfide crosslinking). 2R·→RR (CC crosslinking) It can significantly increase the crosslinking density of vulcanizates, which is beneficial to reduce the compression set of vulcanizates and improve the resilience of vulcanizates. Therefore, the preferred accelerators are CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide), DTDM (4,4′-dithiodimorpholine), and TMTD (tetramethylthiuram disulfide).

[0026] The antioxidant in the aforementioned low-pressure modified, high-resilience nitrile rubber composite material can be a combination of chemical antioxidants and physical protective agents commonly used in the art, such as a system combining quinoline and p-phenylenediamine. This invention does not have particular requirements, but preferably one or more of MB (2-mercaptobenzimidazole), RD (2,2,4-trimethyl-1,2-dihydroquinoline polymer), and 4010NA (N-isopropyl-N'-phenyl-p-phenylenediamine). Rubber antioxidant RD is a ketamine antioxidant with excellent protective efficacy against aging caused by thermo-oxidative aging, and it has no effect on the processing performance, vulcanization characteristics, or physical properties of the vulcanized rubber. MB is a peroxide-decomposing antioxidant. Antioxidant 4010NA is a high-performance general-purpose antioxidant among amine antioxidants, with particularly outstanding anti-ozone aging performance. The physical protective agent is microcrystalline wax or paraffin wax. More preferably, this invention uses antioxidants RD, MB, and 4010NA in combination to increase the protective effect and improve the thermo-oxidative aging resistance of the vulcanized rubber.

[0027] In this invention, in addition to the above-mentioned raw material composition, other processing aids may be added, which can be added according to different needs.

[0028] The Mooney viscosity of nitrile rubber in low-pressure variable and high-resilience nitrile rubber composites can be selected according to the required properties and applications, with the preferred Mooney viscosity being that of the nitrile rubber. The range is 65-90.

[0029] Preferably, the nitrile rubber composite material of the present invention comprises the following raw material components in parts by weight: 100 parts nitrile rubber, 0.5-3 parts stearic acid, 2-3 parts nano zinc oxide, 2-4 parts vulcanizing agent or accelerator, 2-6 parts vulcanizing agent, 15-30 parts silica, 20-80 parts carbon black reinforcing agent, 1%-3% silane coupling agent by weight of silica, and 0.2-4 parts antioxidant. The bound acrylonitrile content of the nitrile rubber is 29%-42%, preferably 31%-35%, and the Mooney viscosity of the nitrile rubber is... The range is 65-90.

[0030] The method for preparing the low-pressure variable, high-resilience nitrile rubber composite material of the present invention involves mixing the components of the above-mentioned rubber composition to form a compound, and then subjecting the compound to vulcanization. As is commonly used in the prior art, one or more stages of mixing are performed to form a compound, followed by vulcanization.

[0031] This invention also provides a preferred method for preparing a low-pressure variable, high-resilience nitrile rubber composite material, comprising the following steps: First stage of mixing: The internal mixer temperature is 50℃~60℃, and the speed is 30~50r / min. Nitrile rubber (raw rubber) is put into the internal mixer and plasticized for 2~8 minutes. At least silica, silane coupling agent, carbon black, zinc oxide, stearic acid and accelerator are added in proportion. The top bolster of the internal mixer is driven to provide mixing pressure to the mixing chamber. Mix for 3~9 minutes to obtain a uniformly mixed masterbatch.

[0032] Two-stage mixing: The masterbatch obtained from the first-stage mixing is re-mixed on an open mill, and at least a vulcanizing agent is added. The mixture is then passed through a thin tube in a triangular shape 3 to 7 times. The roll gap is adjusted before sheeting to obtain a low-pressure modified, high-resilience nitrile rubber compound.

[0033] Vulcanization and setting: After the nitrile rubber compound obtained from the two-stage mixing is allowed to stand for 24h~36h, it is vulcanized in a flat vulcanizing machine at 175±10℃ and 15±5MPa to obtain the product.

[0034] The temperature for nitrile rubber compound to stand is usually room temperature, preferably 20~26℃.

[0035] The zinc oxide used in the examples and comparative examples is as follows: The modified nano zinc oxide was produced by Xuancheng Jingrui New Materials Co., Ltd., with KH550 as the modifier and a particle size of 50nm.

[0036] Nano zinc oxide: Shijiazhuang Guanchi Chemical Technology Co., Ltd., particle size: 30~50nm.

[0037] Ordinary zinc oxide: Gaoyi County Lihe Chemical Co., Ltd., model 001.

[0038] Example 1 Using a combination of 34% acrylonitrile content and Mooney viscosity The composition is as follows: 100 parts of 70 nitrile rubber, 1.5 parts of stearic acid, 3 parts of modified nano zinc oxide (50nm), 2 parts of sulfur, 2.5 parts of DCP, 1.0 part of accelerator DTDM, 0.6 parts of accelerator CZ, 0.4 parts of TMTD, 1 part of HVA-2, 1 part of ZDAA, 15 parts of silica, 50 parts of carbon black N550, 20 parts of carbon black N774, 0.45 parts of Si-69, 1 part of antioxidant MB, 2 parts of antioxidant RD, and 1 part of microcrystalline wax.

[0039] Example 1 describes the preparation process, which includes the following steps: First stage mixing: Raw rubber is added to the internal mixer at 55°C and 35 r / min and plasticized for 4 minutes. Then, silica, silane coupling agent Si-69, carbon black N550 and N774, modified nano zinc oxide, stearic acid, accelerator, etc., are added sequentially in proportion. The top pressure roller of the internal mixer is driven to provide mixing pressure to the mixing chamber. Mixing continues for 4 minutes to obtain a uniformly mixed masterbatch. Second stage mixing: The masterbatch obtained from the first stage mixing is re-milled on an open mill, and vulcanizing agents are added. The mixture is then thinly rolled in a triangular pattern 6 times. The roll gap is adjusted to produce a sheet, resulting in a low-pressure, high-resilience nitrile rubber material. Vulcanization and setting: The nitrile rubber compound obtained from the second stage mixing is allowed to stand at room temperature for 24 hours, and then vulcanized in a flat vulcanizing machine at 175°C and 15 MPa to obtain the finished product.

[0040] Example 2 This embodiment of the low-pressure variable, high-resilience nitrile rubber composite material is composed of the following raw materials in parts by weight: 30% bound acrylonitrile content, Mooney viscosity... The composition is as follows: 100 parts of 65 nitrile rubber, 1.2 parts of stearic acid, 2.5 parts of modified nano zinc oxide (50nm), 2 parts of sulfur, 2.5 parts of DCP, 1.2 parts of accelerator DTDM, 0.8 parts of TMTD, 1 part of HVA-2, 0.5 parts of ZDMA, 35 parts of carbon black N550, 30 parts of carbon black N774, 20 parts of silica, 0.5 parts of KH580, 1 part of antioxidant 4010NA, 2 parts of antioxidant RD, and 1 part of microcrystalline wax.

[0041] Example 2 preparation process includes the following steps: First stage mixing: The internal mixer temperature is 55℃, the rotation speed is 35r / min, the raw rubber is put into the internal mixer and plasticized for 2 minutes, then silica, silane coupling agent KH580, carbon black N550, N774, modified nano zinc oxide, stearic acid, accelerator, etc. are added in proportion, the top bolster of the internal mixer is driven to provide mixing pressure to the mixing chamber, and the mixing is carried out for 3 minutes to obtain a uniformly mixed masterbatch. Second stage mixing: The masterbatch obtained from the first stage mixing is re-mixed on an open mill, and vulcanizing agent, etc. are added. The mixture is then passed through a thin mill and rolled into triangular shapes 6 times. The roller gap is adjusted to produce a sheet to obtain a low-pressure variable, high-resilience nitrile rubber material. Vulcanization and shaping: The nitrile rubber compound obtained from the second stage mixing is allowed to stand at room temperature for 36 hours, and then vulcanized in a flat vulcanizing machine at 180℃ and 15MPa to obtain the product.

[0042] Example 3 This embodiment of the low-pressure variable, high-resilience nitrile rubber composite material is composed of the following raw materials in parts by weight: 34% bound acrylonitrile content, Mooney viscosity... The composition consists of 100 parts of 60 nitrile rubber, 1.2 parts of stearic acid, 2.5 parts of modified nano zinc oxide (50nm), 3 parts of DCP, 1 part of HVA-2, 2 parts of ZDMA, 40 parts of carbon black N550, 35 parts of carbon black N774, 20 parts of silica, 0.5 parts of KH580, 1 part of antioxidant MB, 1.5 parts of antioxidant RD, and 1 part of microcrystalline wax.

[0043] Example 3 preparation process includes the following steps: First stage mixing: The internal mixer temperature is 55℃, the rotation speed is 35r / min, the raw rubber is put into the internal mixer and plasticized for 2 minutes, and then silica, silane coupling agent KH580, carbon black N550, N774, modified nano zinc oxide, stearic acid, vulcanizing agent, etc. are added in sequence according to the proportion. The top bolster of the internal mixer is driven to provide mixing pressure to the mixing chamber. The mixing is carried out for 4 minutes to obtain a uniformly mixed masterbatch. Second stage mixing: The masterbatch obtained from the first stage mixing is re-mixed on an open mill, and vulcanizing agent, etc. are added. The mixture is then passed through a thin mill and rolled in a triangular shape 5 times. The roller gap is adjusted to obtain a low-pressure variable, high-resilience nitrile rubber material. Vulcanization and shaping: The nitrile rubber compound obtained from the second stage mixing is allowed to stand at room temperature for 24 hours, and then vulcanized in a flat vulcanizing machine at 175℃ and 15MPa to obtain the product.

[0044] Example 4 This embodiment is composed of the following raw materials in parts by weight: 32% bound acrylonitrile content, Mooney viscosity... The composition is as follows: 100 parts of 70 nitrile rubber, 1.2 parts of stearic acid, 3 parts of nano zinc oxide, 3 parts of sulfur, 2.5 parts of DCP, 1.5 parts of DTDM, 0.3 parts of CZ, 0.4 parts of TMTD, 1 part of ZDAA, 1 part of ZDMA, 20 parts of carbon black N550, 20 parts of N774, 20 parts of silica, 0.2 parts of coupling agent Si-69, 1 part of antioxidant 4010NA, 2 parts of antioxidant RD, and 1 part of paraffin wax.

[0045] The preparation process in this embodiment is the same as that in Example 1.

[0046] Example 5 This embodiment is composed of the following raw materials in parts by weight: 42% bound acrylonitrile content, Mooney viscosity... The composition includes 100 parts of 90 nitrile rubber, 0.5 parts of stearic acid, 2 parts of modified nano zinc oxide, 1 part of sulfur, 1 part of DCP, 1.5 parts of DTDM, 0.8 parts of CZ, 1 part of ZDAA, 3 parts of ZDMA, 30 parts of carbon black N550, 20 parts of N774, 30 parts of silica, 0.6 parts of coupling agent Si-69, 0.1 parts of antioxidant 4010NA, and 0.1 parts of paraffin wax.

[0047] Example 5 preparation process includes the following steps: First stage mixing: The internal mixer temperature is 60℃, the rotation speed is 30r / min, the raw rubber is put into the internal mixer and plasticized for 8 minutes, and then silica, silane coupling agent Si-69, carbon black N550, N774, modified nano zinc oxide, stearic acid, accelerator, etc. are added in proportion. The top bolster of the internal mixer is driven to provide mixing pressure to the mixing chamber, and the mixing is carried out for 4 minutes to obtain a uniformly mixed masterbatch. Second stage mixing: The masterbatch obtained from the first stage mixing is re-mixed on an open mill, and vulcanizing agent, etc. are added. The mixture is then passed through a thin mill and rolled into triangular shapes 7 times. The roller gap is adjusted to obtain a low-pressure variable, high-resilience nitrile rubber material. Vulcanization and shaping: The nitrile rubber compound obtained from the second stage mixing is allowed to stand at room temperature for 36 hours, and then vulcanized in a flat vulcanizing machine at 175℃ and 20MPa to obtain the product.

[0048] Example 6 This embodiment is composed of the following raw materials in parts by weight: 35% bound acrylonitrile content, Mooney viscosity... The composition includes 100 parts of 80 nitrile rubber, 3 parts of stearic acid, 2.5 parts of modified nano zinc oxide, 2 parts of sulfur, 3 parts of dialkyl peroxide, 1.5 parts of TMTD, 2.5 parts of CZ, 1 part of ZDAA, 1 part of ZDMA, 20 parts of carbon black N550, 60 parts of N774, 15 parts of silica, 0.3 parts of coupling agent KH560, 2 parts of antioxidant MB, and 1 part of paraffin wax.

[0049] Example 6 describes the preparation process, including the following steps: First stage mixing: Raw rubber is added to the internal mixer at 50°C and 50 r / min and plasticized for 3 minutes. Then, silica, silane coupling agent KH560, carbon black N550, N774, modified nano zinc oxide, stearic acid, accelerator, etc., are added sequentially in proportion. The top pressure roller of the internal mixer is driven to provide mixing pressure to the mixing chamber. Mixing is continued for 9 minutes to obtain a uniformly mixed masterbatch. Second stage mixing: The masterbatch obtained from the first stage mixing is re-mixed on an open mill, and vulcanizing agents are added. The mixture is then passed through a thin mill in a triangular pattern three times. The roller gap is adjusted to produce a sheet, resulting in a low-pressure, high-resilience nitrile rubber material. Vulcanization and setting: The nitrile rubber compound obtained from the second stage mixing is allowed to stand at room temperature for 36 hours, and then vulcanized in a flat vulcanizing machine at 175°C and 15 MPa to obtain the finished product.

[0050] Comparative Example 1 This comparative example is basically the same as Example 1, except that it uses nitrile butadiene rubber with low acrylonitrile content, and is composed of the following raw materials in parts by weight: 25% acrylonitrile content, Mooney viscosity... The composition is as follows: 100 parts of 70 nitrile rubber, 1.5 parts of stearic acid, 3 parts of modified nano zinc oxide (50nm), 2 parts of sulfur, 2.5 parts of DCP, 1.0 part of accelerator DTDM, 0.6 parts of accelerator CZ, 0.4 parts of TMTD, 1 part of HVA-2, 1 part of ZDAA, 15 parts of silica, 50 parts of carbon black N550, 20 parts of N774, 0.45 parts of Si-69, 1 part of antioxidant MB, 2 parts of antioxidant RD, and 1 part of microcrystalline wax.

[0051] The preparation process for this comparative example is the same as that for Example 1.

[0052] Comparative Example 2 This comparative example is basically the same as Example 4, except that it uses ordinary zinc oxide and is composed of the following raw materials in parts by weight: 32% acrylonitrile content, Mooney viscosity... The composition is as follows: 100 parts of 70 nitrile rubber, 1.2 parts of stearic acid, 3 parts of ordinary zinc oxide, 3 parts of sulfur, 2.5 parts of DCP, 1.5 parts of DTDM, 0.3 parts of CZ, 0.4 parts of TMTD, 1 part of ZDAA, 1 part of ZDMA, 20 parts of carbon black N550, 20 parts of N774, 20 parts of silica, 0.2 parts of coupling agent Si-69, 1 part of antioxidant 4010NA, 2 parts of antioxidant RD, and 1 part of paraffin wax.

[0053] The preparation process for this comparative example is the same as that for Example 4.

[0054] Comparative Example 3 This comparative example is basically the same as Example 3, except that a common sulfur vulcanization system is used, and it is composed of the following raw materials in parts by weight: 34% acrylonitrile content, Mooney viscosity... The composition is as follows: 100 parts of 60 nitrile rubber, 1.2 parts of stearic acid, 2.5 parts of modified nano zinc oxide (50nm), 3 parts of sulfur, 1 part of CZ, 1 part of TMTD, 40 parts of carbon black N550, 35 parts of carbon black N774, 20 parts of silica, 0.5 parts of KH580, 1 part of antioxidant MB, 1.5 parts of antioxidant RD, and 1 part of microcrystalline wax.

[0055] The preparation process for the comparative example is the same as that for Example 3.

[0056] Comparative Example 4 This comparative example is based on existing technology and consists of the following raw materials in parts by weight: nitrile rubber with a bound acrylonitrile content of 34% and a Mooney viscosity. The composition is 100 parts of 70 nitrile rubber, 1 part of stearic acid, 3 parts of ordinary zinc oxide, 2 parts of magnesium oxide, 0.9 parts of DCP, 2.5 parts of vulcanizing agent HVA-2, 2.5 parts of ZDMA, 20 parts of carbon black N330, 20 parts of silica, 2 parts of Si-69, and 2 parts of antioxidant MB.

[0057] Comparative Example 5 This comparative example is based on existing technology and consists of the following raw materials in parts by weight: nitrile rubber with a bound acrylonitrile content of 34% and a Mooney viscosity. The composition is as follows: 100 parts of 70 nitrile rubber, 1 part stearic acid, 5 parts ordinary zinc oxide, 2.2 parts DCP, 1 part vulcanizing agent HVA-2, 30 parts carbon black N550, 15 parts N330, 8 parts silica, 1 part titanate coupling agent, 1.5 parts antioxidant RD, and 1.5 parts 4020.

[0058] The preparation processes of Comparative Examples 4 and 5 include the following steps: First stage mixing: Raw rubber is added to the internal mixer at 55℃ and 35 r / min and plasticized for 4 minutes. Silica, silane coupling agent, carbon black, ordinary zinc oxide, stearic acid, accelerator, etc., are added sequentially according to the proportions. The top pressure roller of the internal mixer is driven to provide mixing pressure to the mixing chamber. Mixing is continued for 4 minutes to obtain a uniformly mixed masterbatch. Second stage mixing: The masterbatch obtained from the first stage mixing is re-milled on an open mill, and vulcanizing agents are added. The mixture is then passed through a thin mill in a triangular pattern 6 times. The roller gap is adjusted to produce a sheet of nitrile rubber. Vulcanization and setting: The nitrile rubber compound obtained from the second stage mixing is allowed to stand at room temperature for 24 hours, and then vulcanized in a flat vulcanizing machine at 175℃ and 15 MPa to obtain the finished product.

[0059] Comparative Example 6 This comparative example is basically the same as Example 2, except that no silica and silane coupling agent were added. It is composed of the following raw materials in parts by weight: 30% bound acrylonitrile content, Mooney viscosity... The composition is 100 parts of 65 nitrile rubber, 1.2 parts of stearic acid, 2.5 parts of modified nano zinc oxide (50nm), 2 parts of sulfur, 2.5 parts of DCP, 1.2 parts of accelerator DTDM, 0.8 parts of TMTD, 1 part of HVA-2, 0.5 parts of ZDMA, 35 parts of carbon black N550, 30 parts of carbon black N774, 1 part of antioxidant 4010NA, 2 parts of antioxidant RD, and 1 part of microcrystalline wax.

[0060] The mixing process of Comparative Example 6 and Example 2 is the same.

[0061] To better illustrate the advantages of the present invention, the performance of the materials prepared in the embodiments and comparative examples of the present invention was tested using the following methods: The physical properties were tested according to GB / T 528-2009, with a tensile rate of 500 mm / min; hardness was tested according to GB / T 531.1-2008; and resilience was tested according to GB / T 1681-2009. Compression set was tested according to GB / T 7759.1-2015, at 120℃ for 24 hours, with a compression rate of 25%. Hot air aging performance was tested according to GB / T 3512-2014, at 120℃ for 24 hours.

[0062] The test results are shown in Tables 1 and 2.

[0063] Table 1 Properties of vulcanizates in Examples 1-6

[0064] Table 2 Properties of Comparative Examples 1-6 vulcanizates

[0065] A comparison of data from Example 1 and Comparative Example 1 shows that nitrile rubber with a medium-to-high acrylonitrile content exhibits high mechanical strength, including hardness and tensile strength, in its vulcanizate. A comparison of data from Example 3 and Comparative Example 3 shows that the vulcanizate prepared using a peroxide vulcanization system forms -CC- bonds with high bond energy and chemical stability, resulting in good heat resistance. Comparative Example 6, lacking both silica and silane coupling agents in its formulation, exhibits poorer overall performance, indicating that silica and silane coupling agents are beneficial for increasing the degree of vulcanization and improving heat resistance. Examples 1, 2, and 3, employing modified nano-zinc oxide, show higher thermal stability and mechanical strength in their vulcanizates, demonstrating that modified nano-zinc oxide is beneficial for increasing the vulcanization reaction rate and crosslinking degree, and further enhances the performance of the formulated rubber compounds. Furthermore, the compression set of vulcanizates from Examples 1-6 is superior to that of vulcanizates from Comparative Examples 1-6.

[0066] In summary, the nitrile rubber composite material of the present invention has low compression set, high resilience, and excellent tensile strength, which broadens the application range of nitrile rubber. The preparation process of the rubber compound is environmentally friendly, safe and efficient.

Claims

1. A nitrile rubber composite material, characterized in that, The raw material components are as follows by weight: 100 parts of nitrile rubber, 0.5-3 parts of stearic acid, 1.5-3.5 parts of nano zinc oxide, preferably 2-3 parts, 1-4 parts of vulcanizing agent or accelerator, 2-6 parts of vulcanizing agent, 15-30 parts of silica, preferably 15-20 parts, 20-80 parts of carbon black reinforcing agent, 1%-3% of silica mass of silane coupling agent, and 0.2-4 parts of antioxidant; the bound acrylonitrile content of the nitrile rubber is 29%-42%, preferably 31%-35%; the vulcanization system is a peroxide vulcanization system or a composite vulcanization system using a mixture of peroxide vulcanization system and sulfur vulcanization system, preferably a composite vulcanization system using a mixture of peroxide vulcanization system and sulfur vulcanization system.

2. The nitrile rubber composite material according to claim 1, characterized in that, The particle size of the nano zinc oxide is 20~100nm; preferably, the nano zinc oxide is modified nano zinc oxide, and more preferably, the nano zinc oxide is nano zinc oxide modified with a coupling agent.

3. The nitrile rubber composite material according to claim 1, characterized in that, The carbon black reinforcing agent is one or a mixture of several of carbon black N220, carbon black N550, and carbon black N774, preferably two or more types of carbon black; the amount of carbon black reinforcing agent added is preferably 60 to 70 parts.

4. The nitrile rubber composite material according to claim 1, characterized in that, The Mooney viscosity of the nitrile rubber The range is 65-90.

5. The nitrile rubber composite material according to claim 1, characterized in that, The silane coupling agent is one of KH560, KH580, and Si-69.

6. The nitrile rubber composite material according to claim 1, characterized in that, The vulcanizing agent is a peroxide vulcanizing agent or a mixture of peroxide vulcanizing agent and sulfur.

7. The nitrile rubber composite material according to claim 1, characterized in that, The peroxide sulfiding agent in the peroxide sulfidation system is a dialkyl peroxide, a diacyl peroxide, a peroxide ester, or dicumyl peroxide, preferably dicumyl peroxide.

8. The nitrile rubber composite material according to claim 1, characterized in that, The co-curing agent is one or a mixture of N,N'-m-phenylenebismaleimide HVA-2, zinc diacrylate ZDAA, and zinc dimethacrylate ZDMA; preferably, the co-curing agent is 1 to 3 parts.

9. The nitrile rubber composite material according to claim 1, characterized in that, The accelerator is a thiazole and / or thiuram accelerator, preferably one or a mixture of N-cyclohexyl-2-benzothiazole sulfenamide, 4,4′-dithiodimorpholine, and tetramethylthiuram disulfide.

10. The nitrile rubber composite material according to claim 1, characterized in that, The antioxidant is one or more of the following: 2-mercaptobenzimidazole, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, and N-isopropyl-N'-phenyl-p-phenylenediamine.

11. The nitrile rubber composite material according to claim 1, characterized in that, The raw material components, by weight, are as follows: 100 parts nitrile rubber, 0.5-3 parts stearic acid, 2-3 parts nano zinc oxide, 2-4 parts vulcanizing agent or accelerator, 2-6 parts vulcanizing agent, 15-30 parts silica, 20-80 parts carbon black reinforcing agent, 1%-3% silane coupling agent by weight of silica, and 0.2-4 parts antioxidant. The bound acrylonitrile content of the nitrile rubber is 29%-42%, preferably 31%-35%. The Mooney viscosity of the nitrile rubber is... The range is 65-90.

12. The method for preparing the nitrile rubber composite material according to any one of claims 1-11, characterized in that, The raw material components are mixed to form a compound rubber, and then the compound rubber is vulcanized.

13. The preparation method according to claim 12, characterized in that, Prepare according to the following steps: First stage of mixing: The internal mixer temperature is 50℃~60℃, the speed is 30~50r / min. Nitrile rubber is put into the internal mixer and plasticized for 2~8min. Silica, silane coupling agent, carbon black, zinc oxide, stearic acid and accelerator are added in proportion. The top bolster of the internal mixer is driven to provide mixing pressure to the mixing chamber. Mix for 3~9min to obtain a uniformly mixed masterbatch. Two-stage mixing: The masterbatch obtained from the first-stage mixing is recycled on a two-roll mill, and a vulcanizing agent is added. The mixture is then passed through a thin tube in a triangular shape 3 to 7 times. The roll gap is adjusted and the sheet is then sheeted to obtain the nitrile rubber compound. Vulcanization and setting: After the nitrile rubber compound obtained from the two-stage mixing is allowed to stand for 24h~36h, it is vulcanized in a flat vulcanizing machine at 175±10℃ and 15±5MPa to obtain the product.

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