Oil-resistant nitrile rubber, preparation method thereof and application of oil-resistant nitrile rubber in pressure pipe

Abstract

The invention belongs to the technical field of high polymer material rubber, and particularly relates to oil-resistant nitrile rubber as well as a preparation method and application thereof in a pressure pipe. The montmorillonite is modified through itaconic acid, the dispersity of the montmorillonite and the compatibility of the montmorillonite and nitrile rubber are enhanced, the modified montmorillonite further has unsaturated double bonds of itaconic acid and can react with unsaturated double bonds of nitrile rubber, the physical reinforcing effect of the montmorillonite is improved, and the overall mechanical property of rubber is enhanced through chemical crosslinking. The itaconic acid modified montmorillonite is used as a reinforcing agent of the nitrile rubber, and the nitrile rubber which can keep stable size and physical performance under the condition of long-term contact with an oil medium, has high tensile strength and tear resistance, can bear high pressure when being applied to a pressure pipeline, reduces cracks and damage caused by fatigue, and can be used as a high-pressure pipeline. The oil-resistant nitrile rubber material is especially suitable for being applied to pressure pipelines and preventing oil media from permeating and being damaged.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer rubber, and specifically relates to an oil-resistant nitrile rubber and a preparation method thereof and an application thereof in a pressure pipe. Background Art

[0002] Nitrile rubber (NBR) is a random polymer formed by emulsion copolymerization of acrylonitrile and butadiene. Due to the presence of strong polar cyano groups in the NBR molecular chain, NBR has excellent oil resistance, corrosion resistance and good mechanical properties, and is widely used in various important fields such as oil exploration and machinery manufacturing. With the development of society and the progress of the times, various fields have increasingly stringent requirements on the comprehensive performance of rubber materials. Although NBR exhibits outstanding oil resistance and mechanical properties, there are many unsaturated carbon-carbon double bonds in its molecular chain segments, which affect its oil resistance and mechanical properties, thus limiting the application of NBR under special conditions, especially in the application of pressure pipes, where higher requirements are placed on oil resistance and mechanical strength. Therefore, people are in urgent need of developing a nitrile rubber with excellent oil resistance and mechanical properties. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides an oil-resistant nitrile rubber and a preparation method thereof and an application thereof in a pressure pipe.

[0004] An oil-resistant nitrile rubber, composed of the following raw materials: Nitrile rubber (NBR); Modified montmorillonite; Anti-aging agent; Plasticizers; Hydrogenating agents; Active agent.

[0005] Preferably, the oil-resistant nitrile rubber is composed of the following raw materials in parts by mass: 100 parts of nitrile rubber; 3-10 parts of modified montmorillonite; 1-2 parts of antioxidant; 5-20 parts of plasticizer; 1-2.5 parts of hydrogenating agent; 3-5 parts of active agent.

[0006] The antioxidant is at least one of antioxidant RD and antioxidant 4010.

[0007] The plasticizer is at least one of DOP and DOS.

[0008] The hydrogenating agent is at least one of dicumyl peroxide and benzoyl peroxide.

[0009] The active agent is at least one of zinc oxide and stearic acid.

[0010] The preparation method of the modified montmorillonite comprises the following steps: (1) Dispersion treatment of montmorillonite: Mix montmorillonite and water in a mass ratio of 1:(5-10), stir at a speed of 100-200 r / min for 30-60 min, and obtain a montmorillonite dispersion; (2) Preparation of itaconic acid solution: dissolving itaconic acid and sulfuric acid in water to obtain an acid solution; (3) Reaction of itaconic acid and montmorillonite: under stirring at a speed of 100-200 r / min and a reaction temperature of 50-70° C., the acid solution obtained in step (2) is added dropwise to the montmorillonite suspension obtained in step (1) at a rate of 3-5 ml / min. After the addition is completed, the reaction is continued at a constant temperature for 2-4 hours with stirring to obtain a modified montmorillonite suspension. (4) Post-treatment: After the reaction is completed, the modified montmorillonite suspension is centrifuged, washed, and dried to obtain the modified montmorillonite.

[0011] The particle size of the montmorillonite in step (1) is ≤50 μm.

[0012] In step (2), the concentration of itaconic acid in the acid solution is 10-20 wt %, and the concentration of sulfuric acid is 1-2 wt %.

[0013] The mass ratio of the acid solution to the montmorillonite solution in step (3) is 1:(5-10).

[0014] The present invention also provides a method for preparing oil-resistant nitrile rubber, comprising the following steps: (1) Preliminary mixing: add 100 parts of nitrile rubber, 1-2 parts of antioxidant, 5-20 parts of plasticizer and 3-5 parts of active agent into an open mill, and plasticize at 60-80°C for 30-60 minutes to obtain a primary mixing material; (2) Mixing modified montmorillonite: adding 3-10 parts by weight of modified montmorillonite to the primary mixing material obtained in step (1), and mixing for 5-10 minutes at a constant temperature of 80-100° C. to obtain modified nitrile rubber; (3) Hydrogenation treatment: Finally, 1-2.5 parts by weight of a hydrogenating agent is added to the modified nitrile rubber obtained in step (2), and the mixture is kneaded at a constant temperature of 160-180° C. for 10-15 minutes, and then cooled to room temperature to obtain the oil-resistant nitrile rubber.

[0015] The present invention also provides an application of oil-resistant nitrile rubber in a pressure pipe. The rubber material can maintain stable dimensions and physical properties when in long-term contact with oil media, has high tensile strength and tear resistance, can withstand high pressure when used in a pressure pipe, and reduces cracks and damage caused by fatigue. The rubber material is particularly suitable for use in pressure pipes to prevent penetration and damage by oil media.

[0016] Montmorillonite is a natural layered silicate mineral with a layered structure, in which the size between each layer can be adjusted by intercalation, thereby changing its properties. Untreated montmorillonite has poor dispersibility in rubber and limited compatibility with nitrile rubber. Itaconic acid is an organic acid containing two carboxyl groups (-COOH) and one double bond (C=C). The carboxyl groups in itaconic acid react with the surface of montmorillonite through esterification to form a chemical bond (ester bond), or react with the metal ions in montmorillonite to make itaconic acid attached to the surface of montmorillonite, enhancing the compatibility between montmorillonite and nitrile rubber; the unreacted double bonds in itaconic acid remain active, so that the surface of the modified montmorillonite has more reaction sites, which can further cross-link with the unsaturated double bonds in the rubber matrix. This cross-linking structure quickly embeds montmorillonite into the nitrile rubber matrix, which can not only improve the physical reinforcement of montmorillonite, but also enhance the overall mechanical properties of rubber through chemical cross-linking. During this process, the layered structure of montmorillonite is gradually peeled off, and its dispersibility can also be improved.

[0017] Itaconic acid introduces more styrene groups (styrene groups and double bonds) to the surface of montmorillonite, making it easier for styrene materials to cooperate with styrene units in rubber, thus enhancing the material's oil resistance. The layered structure of montmorillonite can also form a physical barrier in rubber media, preventing oil media from penetrating into the rubber matrix. This barrier effect can significantly reduce the swelling effect in rubber media and improve oil resistance.

[0018] Beneficial effects of the present invention: The present invention improves the dispersibility of montmorillonite and the compatibility with acrylonitrile-butadiene rubber by modifying montmorillonite with itaconic acid. The modified montmorillonite also has unsaturated double bonds of itaconic acid and can react with the unsaturated double bonds of acrylonitrile-butadiene rubber, thereby improving the physical reinforcement of montmorillonite and enhancing the overall mechanical properties of rubber through chemical cross-linking. Furthermore, more styrene groups and layered structures are introduced to enhance the oil resistance of acrylonitrile-butadiene rubber. The present invention uses itaconic acid-modified montmorillonite as a reinforcing agent for acrylonitrile-butadiene rubber to obtain an oil-resistant acrylonitrile-butadiene rubber material that can maintain stable size and physical properties in the case of long-term contact with oil medium, has high tensile strength and tear resistance, can withstand high pressure when used in pressure pipes, reduces cracks and damage caused by fatigue, and is particularly suitable for use in pressure pipes to prevent penetration and damage of oil medium. DETAILED DESCRIPTION

[0019] Nitrile rubber, product number: A00724, Wuhan Jiyesheng Chemical Co., Ltd.

[0020] Antiaging agent RD, product number: WD1792, Hubei Wonder Chemical Co., Ltd.

[0021] Plasticizer DOP, product number: W00038, Wuhan Jiyesheng Chemical Co., Ltd.

[0022] Dicumyl peroxide, CAS number: 80-43-3.

[0023] Stearic acid, product number: Y0207, Suzhou Yaco Technology Co., Ltd.

[0024] Montmorillonite, product number: WD0460, Hubei Wonder Chemical Co., Ltd.

[0025] Itaconic acid, CAS number: 97-65-4.

[0026] Carbon black, item number: YM-C-001, Yumu (Ningbo) New Materials Co., Ltd.

[0027] Graphene, Product No.: WD3378, Hubei Wonder Chemical Co., Ltd.

[0028] Montmorillonite, carbon black and graphene were all ground and passed through a filter with a pore size of 50 microns to obtain montmorillonite, carbon black and graphene used in the embodiments and comparative examples.

[0029] Example 1 An oil-resistant nitrile rubber, composed of the following raw materials in parts by mass: 100 parts of nitrile rubber; 7 parts of modified montmorillonite; 1.5 parts of antioxidant; 12 parts of plasticizer; 1.6 parts of hydrogenating agent; 4 parts of active agent.

[0030] The antioxidant is antioxidant RD.

[0031] The plasticizer is DOP.

[0032] The hydrogenating agent is dicumyl peroxide.

[0033] The active agent is stearic acid.

[0034] The preparation method of the modified montmorillonite comprises the following steps: (1) Dispersion treatment of montmorillonite: montmorillonite and water were mixed in a mass ratio of 1:10 and stirred at a speed of 200 r / min for 40 min to obtain a montmorillonite dispersion; (2) Preparation of itaconic acid solution: dissolving itaconic acid and sulfuric acid in water to obtain an acid solution; (3) Reaction of itaconic acid and montmorillonite: under stirring at 200 r / min and reaction conditions at 60° C., the acid solution obtained in step (2) was added dropwise to the montmorillonite suspension obtained in step (1) at a rate of 4 ml / min. After the addition was completed, the reaction was continued at a constant temperature with stirring for 3 h to obtain a modified montmorillonite suspension. (4) Post-treatment: After the reaction is completed, the modified montmorillonite suspension is centrifuged, washed, and dried to obtain the modified montmorillonite.

[0035] In step (2), the concentration of itaconic acid in the acid solution is 16 wt %, and the concentration of sulfuric acid is 1.8 wt %.

[0036] The mass ratio of the acid solution to the montmorillonite solution in step (3) is 1:10.

[0037] The present invention also provides a method for preparing oil-resistant nitrile rubber, comprising the following steps: (1) Preliminary mixing: 100 parts by weight of nitrile rubber, 1.5 parts by weight of antioxidant, 12 parts by weight of plasticizer and 4 parts by weight of active agent were added into an open mixing mill and plasticized at 70° C. for 45 minutes to obtain a primary mixing material; (2) Mixing modified montmorillonite: adding 7 parts by weight of modified montmorillonite to the primary mixing material obtained in step (1), and mixing for 8 minutes at a constant temperature of 90° C. to obtain modified nitrile rubber; (3) Hydrogenation treatment: Finally, 1.6 parts by weight of a hydrogenating agent was added to the modified nitrile rubber obtained in step (2), and the mixture was kneaded at a constant temperature of 160° C. for 12 min, and then cooled to room temperature to obtain the oil-resistant nitrile rubber.

[0038] Example 2 An oil-resistant nitrile rubber, composed of the following raw materials in parts by mass: 100 parts of nitrile rubber; 7 parts of modified montmorillonite; 1.5 parts of antioxidant; 12 parts of plasticizer; 4 parts of active agent.

[0039] The antioxidant is antioxidant RD.

[0040] The plasticizer is DOP.

[0041] The active agent is stearic acid.

[0042] The preparation method of the modified montmorillonite comprises the following steps: (1) Dispersion treatment of montmorillonite: montmorillonite and water were mixed in a mass ratio of 1:10 and stirred at a speed of 200 r / min for 40 min to obtain a montmorillonite dispersion; (2) Preparation of itaconic acid solution: dissolving itaconic acid and sulfuric acid in water to obtain an acid solution; (3) Reaction of itaconic acid and montmorillonite: under stirring at 200 r / min and reaction conditions at 60° C., the acid solution obtained in step (2) was added dropwise to the montmorillonite suspension obtained in step (1) at a rate of 4 ml / min. After the addition was completed, the reaction was continued at a constant temperature with stirring for 3 h to obtain a modified montmorillonite suspension. (4) Post-treatment: After the reaction is completed, the modified montmorillonite suspension is centrifuged, washed, and dried to obtain the modified montmorillonite.

[0043] In step (2), the concentration of itaconic acid in the acid solution is 16 wt %, and the concentration of sulfuric acid is 1.8 wt %.

[0044] The mass ratio of the acid solution to the montmorillonite solution in step (3) is 1:10.

[0045] The present invention also provides a method for preparing oil-resistant nitrile rubber, comprising the following steps: (1) Preliminary mixing: 100 parts by weight of nitrile rubber, 1.5 parts by weight of antioxidant, 12 parts by weight of plasticizer and 4 parts by weight of active agent were added into an open mixing mill and plasticized at 70° C. for 45 minutes to obtain a primary mixing material; (2) Mixing modified montmorillonite: 7 parts by weight of modified montmorillonite were added to the primary mixing material obtained in step (1), and mixing was continued at a constant temperature of 90° C. for 8 minutes to obtain a modified nitrile rubber; mixing was continued at a constant temperature of 160° C. for 12 minutes, and the mixture was cooled to room temperature to obtain the oil-resistant nitrile rubber.

[0046] Example 3 An oil-resistant nitrile rubber, composed of the following raw materials in parts by mass: 100 parts of nitrile rubber; Montmorillonite 7 parts; 1.5 parts of antioxidant; 12 parts of plasticizer; 1.6 parts of hydrogenating agent; 4 parts of active agent.

[0047] The antioxidant is antioxidant RD.

[0048] The plasticizer is DOP.

[0049] The hydrogenating agent is dicumyl peroxide.

[0050] The active agent is stearic acid.

[0051] The present invention also provides a method for preparing oil-resistant nitrile rubber, comprising the following steps: (1) Preliminary mixing: 100 parts by weight of nitrile rubber, 1.5 parts by weight of antioxidant, 12 parts by weight of plasticizer and 4 parts by weight of active agent were added into an open mixing mill and plasticized at 70° C. for 45 minutes to obtain a primary mixing material; (2) Mixing with montmorillonite: adding 7 parts by weight of montmorillonite to the primary mixing material obtained in step (1), and mixing for 8 minutes at a constant temperature of 90° C. to obtain a modified nitrile rubber; (3) Hydrogenation treatment: Finally, 1.6 parts by weight of a hydrogenating agent was added to the modified nitrile rubber obtained in step (2), and the mixture was kneaded at a constant temperature of 160° C. for 12 min, and then cooled to room temperature to obtain the oil-resistant nitrile rubber.

[0052] Example 4 An oil-resistant nitrile rubber, composed of the following raw materials in parts by mass: 100 parts of nitrile rubber; Itaconic acid 7 parts; 1.5 parts of antioxidant; 12 parts of plasticizer; 1.6 parts of hydrogenating agent; 4 parts of active agent.

[0053] The antioxidant is antioxidant RD.

[0054] The plasticizer is DOP.

[0055] The hydrogenating agent is dicumyl peroxide.

[0056] The active agent is stearic acid.

[0057] The present invention also provides a method for preparing oil-resistant nitrile rubber, comprising the following steps: (1) Preliminary mixing: 100 parts by weight of nitrile rubber, 1.5 parts by weight of antioxidant, 12 parts by weight of plasticizer and 4 parts by weight of active agent were added into an open mixing mill and plasticized at 70° C. for 45 minutes to obtain a primary mixing material; (2) Mixing modified montmorillonite: Add 7 parts by weight of itaconic acid to the primary mixing material obtained in step (1), and continue mixing at a constant temperature of 90° C. for 8 minutes to obtain a modified nitrile rubber; (3) Hydrogenation treatment: Finally, 1.6 parts by weight of a hydrogenating agent was added to the modified nitrile rubber obtained in step (2), and the mixture was kneaded at a constant temperature of 160° C. for 12 min, and then cooled to room temperature to obtain the oil-resistant nitrile rubber.

[0058] Example 5 An oil-resistant nitrile rubber, composed of the following raw materials in parts by mass: 100 parts of nitrile rubber; 7 parts of modified montmorillonite; 1.5 parts of antioxidant; 12 parts of plasticizer; 1.6 parts of hydrogenating agent; 4 parts of active agent.

[0059] The antioxidant is antioxidant RD.

[0060] The plasticizer is DOP.

[0061] The hydrogenating agent is dicumyl peroxide.

[0062] The active agent is stearic acid.

[0063] The preparation method of the modified montmorillonite comprises the following steps: (1) Dispersion treatment of montmorillonite: montmorillonite and water were mixed in a mass ratio of 1:10 and stirred at a speed of 200 r / min for 40 min to obtain a montmorillonite dispersion; (2) Preparation of itaconic acid solution: dissolving itaconic acid in water to obtain an acid solution; (3) Reaction of itaconic acid and montmorillonite: under stirring at 200 r / min and reaction conditions at 60° C., the acid solution obtained in step (2) was added dropwise to the montmorillonite suspension obtained in step (1) at a rate of 4 ml / min. After the addition was completed, the reaction was continued at a constant temperature with stirring for 3 h to obtain a modified montmorillonite suspension. (4) Post-treatment: After the reaction is completed, the modified montmorillonite suspension is centrifuged, washed, and dried to obtain the modified montmorillonite.

[0064] The concentration of itaconic acid in the acid solution in step (2) is 16 wt %.

[0065] The mass ratio of the acid solution to the montmorillonite solution in step (3) is 1:10.

[0066] The present invention also provides a method for preparing oil-resistant nitrile rubber, comprising the following steps: (1) Preliminary mixing: 100 parts by weight of nitrile rubber, 1.5 parts by weight of antioxidant, 12 parts by weight of plasticizer and 4 parts by weight of active agent were added into an open mixing mill and plasticized at 70° C. for 45 minutes to obtain a primary mixing material; (2) Mixing modified montmorillonite: adding 7 parts by weight of modified montmorillonite to the primary mixing material obtained in step (1), and mixing for 8 minutes at a constant temperature of 90° C. to obtain modified nitrile rubber; (3) Hydrogenation treatment: Finally, 1.6 parts by weight of a hydrogenating agent was added to the modified nitrile rubber obtained in step (2), and the mixture was kneaded at a constant temperature of 160° C. for 12 min, and then cooled to room temperature to obtain the oil-resistant nitrile rubber.

[0067] Comparative Example 1 An oil-resistant nitrile rubber, composed of the following raw materials in parts by mass: 100 parts of nitrile rubber; 7 parts of modified carbon black; 1.5 parts of antioxidant; 12 parts of plasticizer; 1.6 parts of hydrogenating agent; 4 parts of active agent.

[0068] The antioxidant is antioxidant RD.

[0069] The plasticizer is DOP.

[0070] The hydrogenating agent is dicumyl peroxide.

[0071] The active agent is stearic acid.

[0072] The preparation method of the modified carbon black comprises the following steps: (1) Dispersion treatment of carbon black: Mix carbon black and water in a mass ratio of 1:10 and stir at a speed of 200 r / min for 40 min to obtain a carbon black dispersion; (2) Preparation of itaconic acid solution: dissolving itaconic acid and sulfuric acid in water to obtain an acid solution; (3) Reaction of itaconic acid and carbon black: under stirring at 200 r / min and reaction conditions at 60° C., the acid solution obtained in step (2) is added dropwise to the carbon black suspension obtained in step (1) at a rate of 4 ml / min. After the addition is completed, the reaction is continued at a constant temperature with stirring for 3 h to obtain a modified carbon black suspension. (4) Post-treatment: After the reaction is completed, the modified carbon black suspension is centrifuged, washed, and dried to obtain the modified carbon black.

[0073] In step (2), the concentration of itaconic acid in the acid solution is 16 wt %, and the concentration of sulfuric acid is 1.8 wt %.

[0074] The mass ratio of the acid solution to the carbon black solution in step (3) is 1:10.

[0075] The present invention also provides a method for preparing oil-resistant nitrile rubber, comprising the following steps: (1) Preliminary mixing: 100 parts by weight of nitrile rubber, 1.5 parts by weight of antioxidant, 12 parts by weight of plasticizer and 4 parts by weight of active agent were added into an open mixing mill and plasticized at 70° C. for 45 minutes to obtain a primary mixing material; (2) Mixing modified carbon black: Add 7 parts by weight of modified carbon black to the primary mixing material obtained in step (1), and continue mixing at a constant temperature of 90° C. for 8 minutes to obtain modified nitrile rubber; (3) Hydrogenation treatment: Finally, 1.6 parts by weight of a hydrogenating agent was added to the modified nitrile rubber obtained in step (2), and the mixture was kneaded at a constant temperature of 160° C. for 12 min, and then cooled to room temperature to obtain the oil-resistant nitrile rubber.

[0076] Comparative Example 2 An oil-resistant nitrile rubber, composed of the following raw materials in parts by mass: 100 parts of nitrile rubber; 7 parts of modified graphene; 1.5 parts of antioxidant; 12 parts of plasticizer; 1.6 parts of hydrogenating agent; 4 parts of active agent.

[0077] The antioxidant is antioxidant RD.

[0078] The plasticizer is DOP.

[0079] The hydrogenating agent is dicumyl peroxide.

[0080] The active agent is stearic acid.

[0081] The preparation method of the modified graphene comprises the following steps: (1) Graphene dispersion treatment: Graphene and water were mixed at a mass ratio of 1:10 and stirred at a speed of 200 r / min for 40 min to obtain a graphene dispersion; (2) Preparation of itaconic acid solution: dissolving itaconic acid and sulfuric acid in water to obtain an acid solution; (3) Reaction of itaconic acid and graphene: under stirring at 200 r / min and 60° C., the acid solution obtained in step (2) was added dropwise to the graphene suspension obtained in step (1) at a rate of 4 ml / min. After the addition was completed, the mixture was stirred at a constant temperature for 3 h to obtain a modified graphene suspension. (4) Post-treatment: After the reaction is completed, the modified graphene suspension is centrifuged, washed, and dried to obtain the modified graphene.

[0082] In step (2), the concentration of itaconic acid in the acid solution is 16 wt %, and the concentration of sulfuric acid is 1.8 wt %.

[0083] The mass ratio of the acid solution to the graphene solution in step (3) is 1:10.

[0084] The present invention also provides a method for preparing oil-resistant nitrile rubber, comprising the following steps: (1) Preliminary mixing: 100 parts by weight of nitrile rubber, 1.5 parts by weight of antioxidant, 12 parts by weight of plasticizer and 4 parts by weight of active agent were added into an open mixing mill and plasticized at 70° C. for 45 minutes to obtain a primary mixing material; (2) Mixing modified graphene: adding 7 parts by weight of modified graphene to the primary mixed material obtained in step (1), and mixing for 8 minutes at a constant temperature of 90° C. to obtain modified nitrile rubber; (3) Hydrogenation treatment: Finally, 1.6 parts by weight of a hydrogenating agent was added to the modified nitrile rubber obtained in step (2), and the mixture was kneaded at a constant temperature of 160° C. for 12 min, and then cooled to room temperature to obtain the oil-resistant nitrile rubber.

[0085] Comparative Example 3 An oil-resistant nitrile rubber, composed of the following raw materials in parts by mass: 100 parts of nitrile rubber; 1.5 parts of antioxidant; 12 parts of plasticizer; 1.6 parts of hydrogenating agent; 4 parts of active agent.

[0086] The antioxidant is antioxidant RD.

[0087] The plasticizer is DOP.

[0088] The hydrogenating agent is dicumyl peroxide.

[0089] The active agent is stearic acid.

[0090] The present invention also provides a method for preparing oil-resistant nitrile rubber, comprising the following steps: (1) Preliminary mixing: 100 parts by weight of nitrile rubber, 1.5 parts by weight of antioxidant, 12 parts by weight of plasticizer and 4 parts by weight of active agent were added into an open mixing mill and plasticized at 70° C. for 45 minutes to obtain a primary mixing material; (2) Mixing is continued at a constant temperature of 90°C for 8 minutes to obtain modified nitrile rubber; (3) Hydrogenation treatment: Finally, 1.6 parts by weight of a hydrogenating agent was added to the modified nitrile rubber obtained in step (2), and the mixture was kneaded at a constant temperature of 160° C. for 12 min, and then cooled to room temperature to obtain the oil-resistant nitrile rubber.

[0091] Test Example 1 The oil resistance of the oil-resistant nitrile rubber obtained in each embodiment and comparative example was measured with reference to GB / T 1690-2010 “Test method for liquid resistance of vulcanized rubber or thermoplastic rubber”. The results are shown in Table 1.

[0092] Table 1: Oil resistance test results Quality change rate / % Volume change rate / % Example 1 3.5 4.2 Example 2 3.6 4.5 Example 3 4.0 5.0 Example 4 4.3 5.5 Example 5 3.8 4.8 Comparative Example 1 6.5 7.2 Comparative Example 2 5.5 6.8 Comparative Example 3 8.0 9.0 Test Example 2 The mechanical properties of the oil-resistant nitrile rubber obtained in each embodiment and comparative example were measured with reference to GB / T 528-2009 “Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber”. The results are shown in Table 2.

[0093] Table 2: Mechanical properties test results Tensile strength / MPa Elongation at break / % Example 1 18.5 450 Example 2 18.3 410 Example 3 17.8 400 Example 4 17.5 395 Example 5 18.0 405 Comparative Example 1 15.0 380 Comparative Example 2 16.5 390 Comparative Example 3 14.0 350 As can be seen from Table 1 and Table 2, the oil-resistant nitrile rubber prepared in Example 1 has the best oil resistance and mechanical properties. This shows that Example 1 modifies montmorillonite with itaconic acid to enhance the dispersibility of montmorillonite and the compatibility with nitrile rubber. The modified montmorillonite also has unsaturated double bonds of itaconic acid, which can react with the unsaturated double bonds of nitrile rubber, thereby improving the physical reinforcement of montmorillonite and enhancing the overall mechanical properties of rubber through chemical crosslinking. Furthermore, more styrene groups and layered structures are introduced to enhance the oil resistance of nitrile rubber.

[0094] Compared with Example 1, Example 2 does not add a hydrogenating agent, which can produce interruptions at high temperatures, trigger cross-linking reactions between rubber molecular chains, and form a three-dimensional network structure, thereby enhancing the mechanical strength and oil resistance of the rubber. Therefore, the oil resistance and mechanical strength of Example 2 are slightly lower than those of Example 1. Compared with Example 1, Example 3 uses montmorillonite that has not been treated with itaconic acid. Montmorillonite can introduce more unsaturated double bonds on the surface of montmorillonite through itaconic acid treatment, enhancing the compatibility and interfacial bonding between montmorillonite and the nitrile rubber matrix, so the oil resistance and mechanical properties are both lower than those of Example 1. Example 4 uses itaconic acid to replace traditional montmorillonite, and there is no montmorillonite in the formula. Itaconic acid itself has a certain stability and can improve the oil resistance of nitrile rubber, but compared with modified montmorillonite, it lacks physical reinforcement, so the improvement in tensile strength and wear resistance is limited, and montmorillonite is not used as a physical reinforcing agent, resulting in a decrease in oil resistance and mechanical properties. In Example 5, montmorillonite was treated with itaconic acid, but sulfuric acid was not added as a catalyst. In the process of forming montmorillonite treated with itaconic acid, the role of sulfuric acid is to catalyze the reaction between carboxyl groups and the surface of montmorillonite. The lack of addition of sulfuric acid results in limited binding force between itaconic acid and montmorillonite, and the itaconic acid modification effect is poor. Therefore, the effect of modifying montmorillonite is slightly worse, resulting in the material's oil resistance and mechanical strength being inferior to those of Example 1.

[0095] In Comparative Example 1, carbon black is used to replace montmorillonite. Carbon black has a good reinforcing effect and can improve the mechanical strength of rubber. However, due to the poor compatibility of carbon black with the rubber matrix, it is difficult to significantly improve the oil resistance of rubber. Therefore, the oil resistance is significantly lower than that of montmorillonite, and the mechanical strength is also lower. In Comparative Example 2, graphene is used to replace montmorillonite, and its oil resistance and mechanical properties are not as good as montmorillonite. The present invention believes that this is because the dispersibility and compatibility of graphene with the rubber matrix are not as good as montmorillonite. No new montmorillonite or other reinforcing agents are added in Comparative Example 3. The mechanical properties of nitrile rubber are completely dependent on its own molecular structure, so the tensile strength and elongation at break are significantly reduced. At the same time, due to the lack of reinforcing materials such as reinforcing agents such as nitrile, the oil resistance performance is also significantly reduced.

[0096] In summary, modified montmorillonite is a key factor in improving the oil resistance and mechanical strength of nitrile rubber. The modified montmorillonite treated with itaconic acid and sulfuric acid can significantly improve the oil resistance and mechanical properties of rubber. Although carbon black and graphene have physical reinforcement effects, their improvement on the oil resistance of rubber is limited. Montmorillonite modified with itaconic acid has the best reinforcement effect.

Claims

1. An oil-resistant nitrile rubber, characterized in that: It is composed of the following raw materials: Nitrile rubber; Modified montmorillonite; Anti-aging agent; Plasticizers; Hydrogenating agents; Active agent.

2. The oil-resistant nitrile rubber according to claim 1, characterized in that: By mass, it is composed of the following raw materials: 100 parts of nitrile rubber; 3-10 parts of modified montmorillonite; 1-2 parts of antioxidant; 5-20 parts of plasticizer; 1-2.5 parts of hydrogenating agent; 3-5 parts of active agent.

3. The oil-resistant nitrile rubber according to claim 2, characterized in that: The hydrogenating agent is at least one of dicumyl peroxide and benzoyl peroxide.

4. The oil-resistant nitrile rubber according to claim 2, characterized in that: The active agent is at least one of zinc oxide and stearic acid.

5. The oil-resistant nitrile rubber according to claim 2, characterized in that: The preparation method of the modified montmorillonite comprises the following steps: (1) Dispersion treatment of montmorillonite: Mix montmorillonite and water in a mass ratio of 1:(5-10), stir at a speed of 100-200 r / min for 30-60 min, and obtain a montmorillonite dispersion; (2) Preparation of itaconic acid solution: dissolving itaconic acid and sulfuric acid in water to obtain an acid solution; (3) Reaction of itaconic acid and montmorillonite: under stirring at a speed of 100-200 r / min and a reaction temperature of 50-70° C., the acid solution obtained in step (2) is added dropwise to the montmorillonite suspension obtained in step (1) at a rate of 3-5 ml / min. After the addition is completed, the reaction is continued at a constant temperature for 2-4 hours with stirring to obtain a modified montmorillonite suspension. (4) Post-treatment: After the reaction is completed, the modified montmorillonite suspension is centrifuged, washed, and dried to obtain the modified montmorillonite.

6. The oil-resistant nitrile rubber according to claim 5, characterized in that: The particle size of the montmorillonite in step (1) is ≤50 μm.

7. The oil-resistant nitrile rubber according to claim 5, characterized in that: In step (2), the concentration of itaconic acid in the acid solution is 10-20 wt %, and the concentration of sulfuric acid is 1-2 wt %.

8. The oil-resistant nitrile rubber according to claim 5, characterized in that: The mass ratio of the acid solution to the montmorillonite solution in step (3) is 1:(5-10).

9. A method for preparing the oil-resistant nitrile rubber according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) Preliminary mixing: add 100 parts of nitrile rubber, 1-2 parts of antioxidant, 5-20 parts of plasticizer and 3-5 parts of active agent into an open mill, and plasticize at 60-80°C for 30-60 minutes to obtain a primary mixing material; (2) Mixing modified montmorillonite: adding 3-10 parts by weight of modified montmorillonite to the primary mixing material obtained in step (1), and mixing for 5-10 minutes at a constant temperature of 80-100° C. to obtain modified nitrile rubber; (3) Hydrogenation treatment: Finally, 1-2.5 parts by weight of a hydrogenating agent is added to the modified nitrile rubber obtained in step (2), and the mixture is kneaded at a constant temperature of 160-180° C. for 10-15 minutes, and then cooled to room temperature to obtain the oil-resistant nitrile rubber.

10. Use of the oil-resistant nitrile rubber according to any one of claims 1 to 8 in a pressure pipe.