Cold-resistant rubber and preparation method thereof

Abstract

The invention discloses cold-resistant rubber and a preparation method thereof, and relates to the field of rubber materials. The cold-resistant rubber comprises the following raw materials in parts by weight: 38-55 parts of nitrile rubber; 25 to 35 parts of acrylate rubber; 20-28 parts of butadiene rubber; 1.2-2 parts of a vulcanizing agent; 1.7 to 2.5 parts of an accelerant; 2-3 parts of an anti-aging agent; 0.5 to 1 part of stearic acid; 0.3 to 0.6 part of microcrystalline wax; 3 to 5 parts of coumarone resin; 15 to 23 parts of carbon black; 4 to 7 parts of cyclohexane 1, 2-diisononyl diformate; 11 to 17 parts of hydroxylated carbon nanotubes; 5-9 parts of softened ramie fiber; the softened ramie fibers are selected from ramie fibers subjected to NaOH / urea / thiourea low-temperature softening treatment. The invention prepares the rubber which is used for the sole material and has good cold resistance and low-temperature elasticity.

Description

Technical Field

[0001] This invention relates to the field of rubber materials, and in particular to a cold-resistant rubber and its preparation method. Background Technology

[0002] Rubber is divided into two main categories: natural and synthetic. Common characteristics include high elasticity, rapid recovery after the removal of external force, minimal permanent deformation, and good energy storage properties. Rubber can be used as a material for shoe soles, improving comfort, providing softness and wear resistance, and withstanding repeated bending, stretching, and compression without damage.

[0003] Existing shoe sole rubber materials come in a variety of formulations, primarily emphasizing properties such as abrasion resistance, slip resistance, elasticity, tear resistance, aging resistance, and corrosion resistance. However, existing rubbers used for shoe soles have poor cold resistance; when frozen at -15°C for a period of time, their hardness increases, while their toughness and flexibility decrease significantly, leading to hardening and cracking of the sole and affecting its lifespan. Summary of the Invention

[0004] In order to prepare a rubber with good cold resistance and low-temperature elasticity for use in shoe sole materials, this application provides a cold-resistant rubber and a method for preparing the same.

[0005] The present application provides a cold-resistant rubber and its preparation method, which adopts the following technical solution: In a first aspect, this application provides a cold-resistant rubber comprising the following raw materials in parts by weight: 38-55 parts of nitrile rubber; 25-35 parts of acrylic rubber; 20-28 parts of butadiene rubber; 1.2-2 parts of vulcanizing agent; Accelerator 1.7-2.5 parts; Anti-aging agent 2-3 parts; Stearic acid 0.5-1 part; Microcrystalline wax 0.3-0.6 parts; 3-5 parts of coumarone resin; 15-23 parts carbon black; 4-7 parts of diisononyl cyclohexane 1,2-dicarboxylate; 11-17 parts of hydroxylated carbon nanotubes; Soften 5-9 parts of ramie fiber; The softened ramie fiber is selected from ramie fibers that have undergone low-temperature softening treatment with NaOH / urea / thiourea.

[0006] By adopting the above technical solution, nitrile rubber, acrylic rubber, and cis-butadiene rubber are compounded in the rubber material. By selecting rubbers with high mechanical properties and low glass transition temperatures, the cold resistance of the rubber is improved. The environmentally friendly plasticizer diisononyl cyclohexane 1,2-dicarboxylate is added to the rubber material to further enhance the cold resistance. Hydroxylated carbon nanotubes and softened ramie fibers are selected as fillers, which can consume energy during crack propagation, inhibit the freezing of rubber molecular chains at low temperatures, and inhibit the hardening and cracking of rubber in cold environments. Through the synergistic effect of the two, a "nano-micro" multi-scale reinforcing network is formed, achieving simultaneous improvement in mechanical properties and low-temperature elasticity.

[0007] In the formulation of the cold-resistant rubber in this application, the functions of each raw material are as follows: Nitrile rubber: As the main material, it has good oil resistance, good wear resistance, excellent elasticity, comfortable feel, and is easy to process; Acrylic rubber: Excellent heat resistance, oil resistance, ozone resistance, and weather resistance; Butadiene rubber: After vulcanization, it has excellent cold resistance, abrasion resistance and elasticity, generates little heat under dynamic load, and has good aging resistance; Vulcanizing agent: promotes the vulcanization reaction of rubber; Accelerators can shorten vulcanization time, lower vulcanization temperature, reduce the amount of vulcanizing agent used, and improve the physical and mechanical properties of rubber. Anti-aging agent: heat and oxygen stabilizer with good antioxidant and heat resistance; Stearic acid: It can be used as a plasticizer and softener, and also as a mold release agent for rubber products; Microcrystalline wax: Improves the aging resistance and increases the flexibility of rubber; Coumarone resin: easy to process and improves performance; Carbon black: As a reinforcing agent for rubber, it greatly improves the wear resistance and tear resistance of rubber, and improves the processing performance of rubber;

[0008] Optionally, the nitrile rubber is selected from polycaprolactone-grafted nitrile rubber and is prepared through the following steps: Add 10-15 parts by weight of nitrile rubber to tetrahydrofuran and stir to dissolve to obtain a rubber solution. Add 0.1-0.3 parts by weight of benzoyl peroxide to the rubber solution, and slowly add 7-12 parts by weight of caprolactone monomer to the solution. Heat to 70-90℃ and react for 4-8 hours under nitrogen protection. After the reaction was completed, the mixture was cooled to room temperature, and the reaction solution was slowly poured into a large amount of methanol to precipitate the product. The solid product was obtained by filtration, washed with methanol, and then dried under vacuum to obtain polycaprolactone-grafted nitrile rubber.

[0009] By adopting the above technical solution, nitrile rubber with poor cold resistance is modified by introducing soft polycaprolactone segments to improve the flexibility of the rubber molecular chain, thereby making it suitable for use in cold environments.

[0010] Optionally, the hydroxylated carbon nanotubes are prepared by the following steps: Carbon nanotubes were dissolved in deionized water, and the pH was adjusted to 3-4 with dilute hydrochloric acid. Under ultrasonic stirring, a mixture of hydrogen peroxide and ferrous chloride solution with a molar ratio of 10:1 was prepared and added dropwise to the carbon nanotube solution at a rate of 45-48 drops / min. The weight ratio of carbon nanotubes to the volume ratio of the mixture was 0.8-1.1:200. The mixture was ultrasonically stirred for 4-6 hours, filtered, and dried to obtain hydroxylated carbon nanotubes.

[0011] By adopting the above technical solution, -OH is introduced on the surface of carbon nanotubes to form strong hydrogen bonds or chemical bonds with rubber molecular chains, thereby improving dispersibility and interfacial bonding, improving the degree of freedom of movement of rubber molecular chains, delaying low-temperature embrittlement, resisting crack propagation, and improving the cold resistance of rubber.

[0012] Optionally, the acrylate rubber comprises the following raw materials in parts by weight: 55-70 parts of ethyl acrylate; 15-22 parts of methoxyethyl acrylate; 6-9 parts of methoxylated polyethylene glycol acrylate; Vinyl chloroacetate 2.5-4 parts.

[0013] By adopting the above technical solution, for acrylic rubber, a cold-resistant monomer containing a flexible ether chain is selected for copolymerization to achieve a balance between oil resistance and cold resistance, which greatly reduces the glass transition temperature of acrylic rubber. At the same time, vinyl chloroacetate is selected as the vulcanization point monomer to overcome the problems of difficult rubber processing, easy sticking to rollers, and difficulty in demolding after vulcanization.

[0014] Optionally, the softened ramie fiber is obtained through the following steps: The NaOH / urea / thiourea solution was cooled to -5 to 1°C in a cryogenic bath, wherein the mass concentration of the NaOH / urea / thiourea solution was: NaOH 7-8%, urea 8-10%, and thiourea 6.5-7.5%. The washed and degummed ramie fibers are immersed in a solution at a bath ratio of 1:10-20, stirred continuously for 15-20 minutes, then removed, washed with water, and dried at 60-80℃ to obtain softened ramie fibers.

[0015] By adopting the above technical solution, the crystallinity of softened ramie fibers is significantly reduced and the surface roughness is increased, which can improve the mechanical interlocking with rubber and improve low-temperature toughness and durability.

[0016] Optionally, the vulcanizing agent is selected from one or more of sulfur, zinc oxide, and dibenzenesulfonyl hydrazine ether.

[0017] Optionally, the accelerator is selected from one or more of accelerators DM, NS, CZ, NA-22, and TT.

[0018] Optionally, the antioxidant is selected from one or more of di-tert-butyl-p-cresol, 2-thiol-benzimidazole, N-isopropyl-N'-phenyl-p-phenylenediamine, and 2,2,4-trimethyl-1,2-dihydroquinoline polymers.

[0019] Optionally, the nitrile rubber has a Mooney viscosity of 45-65 and an acrylonitrile mass fraction of 25-30%.

[0020] By adopting the above technical solution, the parameters of nitrile rubber can be controlled to achieve a balance between its cold resistance, oil resistance, and processing performance.

[0021] Secondly, this application provides a method for preparing cold-resistant rubber, comprising the following steps: Nitrile rubber, acrylate rubber, and butadiene rubber are mixed in an internal mixer at a temperature of 80-100℃ for 10-12 minutes. Other raw materials except vulcanizing agents and accelerators are added to the internal mixer and mixed at a temperature of 100-120℃ for 5-10 minutes. After discharge, the mixture is cooled at room temperature for 24 hours and used as a base rubber for future use. The base rubber, accelerator, and vulcanizing agent are mixed evenly on a two-roll mill at a temperature of 50-80℃ for 5-8 minutes. After being sheeted from the two-roll mill, the rubber is cooled to obtain cold-resistant rubber.

[0022] By adopting the above technical solution, cold-resistant rubber suitable for shoe sole materials can be obtained through mixing and open-milling steps, and the processing method is simple.

[0023] Optionally, in the open mill, the roll gap is 2mm.

[0024] In summary, this application has at least one of the following beneficial effects: 1. In the rubber material, nitrile rubber, acrylic rubber, and cis-butadiene rubber are selected for blending. By combining rubbers with high mechanical properties and low glass transition temperatures, the cold resistance of the rubber is improved. The environmentally friendly plasticizer diisononyl cyclohexane 1,2-dicarboxylate is added to the rubber material to further enhance the cold resistance. The fillers selected are hydroxylated carbon nanotubes and softened ramie fibers, which can consume energy during crack propagation, inhibit the freezing of rubber molecular chains at low temperatures, and inhibit the hardening and cracking of rubber in cold environments. Through the synergistic effect of the two, a "nano-micro" multi-scale reinforcing network is formed, achieving simultaneous improvement in mechanical properties and low-temperature elasticity.

[0025] 2. To address the poor cold resistance of nitrile rubber, a polycaprolactone segment with a soft segment is introduced to improve the flexibility of the rubber molecular chain, thereby making it suitable for use in extremely cold environments. Detailed Implementation

[0026] The present application will be further described in detail below with reference to Examples 1-6 and Comparative Examples 1-2. Preparation Example

[0027] Preparation Example 1-1 Preparation of polycaprolactone-grafted nitrile butadiene rubber 10g of nitrile rubber was added to 100ml of tetrahydrofuran and stirred to dissolve to obtain a rubber solution. Then, 0.1g of benzoyl peroxide was added to the solution, and 7g of caprolactone monomer was slowly added dropwise. The temperature was raised to 70℃ and the reaction was carried out under nitrogen protection for 8 hours. After the reaction was completed, the mixture was cooled to room temperature, and the reaction solution was slowly poured into a large amount of methanol to precipitate the product. The solid product was obtained by filtration, washed with methanol, and then dried under vacuum to obtain polycaprolactone-grafted nitrile rubber.

[0028] Preparation Examples 1-2 Preparation of polycaprolactone-grafted nitrile butadiene rubber Add 15g of nitrile rubber to 150ml of tetrahydrofuran and stir to dissolve to obtain a rubber solution. Then add 0.3g of benzoyl peroxide to the solution and slowly add 12g of caprolactone monomer. Heat to 90℃ and react for 4h under nitrogen protection. After the reaction was completed, the mixture was cooled to room temperature, and the reaction solution was slowly poured into a large amount of methanol to precipitate the product. The solid product was obtained by filtration, washed with methanol, and then dried under vacuum to obtain polycaprolactone-grafted nitrile rubber.

[0029] Preparation Example 2-1 Preparation of carbonylated carbon nanotubes Dissolve 0.8g of carbon nanotubes in 50ml of deionized water, adjust the pH to 3-4 with dilute hydrochloric acid, and under ultrasonic stirring, use a hydrogen peroxide and ferrous chloride solution with a molar ratio of 10:1 to form a mixture. Add 200ml of the mixture to the carbon nanotube solution at a rate of 45 drops / min, ultrasonically stir for 4 hours, filter and dry to obtain hydroxylated carbon nanotubes.

[0030] Preparation Example 2-2 Preparation of carbonylated carbon nanotubes Dissolve 1.1g of carbon nanotubes in 70ml of deionized water, adjust the pH to 3-4 with dilute hydrochloric acid, and under ultrasonic stirring, use a hydrogen peroxide and ferrous chloride solution with a molar ratio of 10:1 to form a mixture. Add 200ml of the mixture to the carbon nanotube solution at a rate of 48 drops / min, ultrasonically stir for 6 hours, filter and dry to obtain hydroxylated carbon nanotubes.

[0031] Preparation Example 3-1 Acrylic rubber, including the following raw materials: 55g of ethyl acrylate; 15g of methoxyethyl acrylate; 6g of methoxy polyethylene glycol acrylate; Vinyl chloroacetate 2.5g.

[0032] Acrylic rubber is prepared by emulsion polymerization, and the specific steps are as follows: Add 200g of deionized water, 1g of OP-10 emulsifier, and 1.5g of sodium dodecyl sulfate to a three-necked flask, heat to 90°C, purge with nitrogen for 30 minutes, then cool to 60°C under nitrogen protection, add 85% of the mixed monomers, continue cooling to 40°C, add 0.2g of ammonium persulfate, add 0.2g of sodium bisulfite after 5 minutes, and add the remaining mixed monomers dropwise while maintaining the temperature at 50°C for 2 hours. After the addition is complete, keep warm for 30 minutes to obtain the emulsion. Pour the emulsion into a beaker, dilute it with 5 times the amount of deionized water, turn on the stirrer and heat it to 85°C, add CaCl2 solution dropwise, wash the flocculated polymer with deionized water at 60°C 3-4 times, and then dry the washed product in a vacuum drying oven at 50°C to constant weight to obtain acrylate rubber.

[0033] Preparation Example 3-2 Acrylic rubber, including the following raw materials: 70g of ethyl acrylate; 22g of methoxyethyl acrylate; 9g of methoxy polyethylene glycol acrylate; Vinyl chloroacetate 4g.

[0034] Acrylic rubber is prepared by emulsion polymerization, and the specific steps are as follows: Add 250g of deionized water, 1.5g of OP-10 emulsifier, and 1.8g of sodium dodecyl sulfate to a three-necked flask, heat to 90°C, purge with nitrogen for 30 minutes, then cool to 60°C under nitrogen protection, add 85% of the mixed monomers, continue cooling to 40°C, add 0.25g of ammonium persulfate, add 0.25g of sodium bisulfite after 5 minutes, and add the remaining mixed monomers dropwise while maintaining the temperature at 50°C for 3 hours. After the addition is complete, keep warm for 40 minutes to obtain the emulsion. Pour the emulsion into a beaker, dilute with 5 times the amount of deionized water, turn on the stirrer and heat to 85°C, add CaCl2 solution dropwise, wash the flocculated polymer with deionized water at 60°C 3-4 times, and then dry the washed product in a vacuum drying oven at 55°C to constant weight to obtain acrylate rubber.

[0035] Preparation Example 4-1 Preparation of softened ramie fibers The NaOH / urea / thiourea solution was cooled to 1°C in a cryogenic bath, wherein the mass concentration of the NaOH / urea / thiourea solution was: NaOH 7%, urea 8%, and thiourea 6.5%. The washed and degummed ramie fibers were immersed in a solution at a liquor ratio of 1:20, stirred continuously for 15 minutes, removed, washed with water, and dried at 60°C to obtain softened ramie fibers.

[0036] Preparation Example 4-2 Preparation of softened ramie fibers The NaOH / urea / thiourea solution was cooled to -5°C in a cryogenic bath, wherein the mass concentration of the NaOH / urea / thiourea solution was: NaOH 8%, urea 10%, and thiourea 7.5%. The washed and degummed ramie fibers were immersed in a solution at a bath ratio of 1:10, stirred continuously for 20 minutes, removed, washed with water, and dried at 80°C to obtain softened ramie fibers. Example

[0037] Example 1 A cold-resistant rubber, comprising the following raw materials: 38g of nitrile rubber, 33% acrylonitrile content, Mooney viscosity 50, grade Zhenjiang Nandi 1052; 25g of acrylate rubber, selected from the acrylate rubber prepared in Preparation Example 3-1; 20g of butadiene rubber, purchased from Dongguan Shengli New Material Co., Ltd., model number XH03402GFPSN; 1.2g of vulcanizing agent, sulfur is selected; 1.7g of accelerator was used, specifically 1g of accelerator DM and 0.7g of accelerator NS. Antioxidant 2g, selected as di-tert-butyl-p-cresol; Stearic acid 0.5g; 0.3g of microcrystalline wax; 3g of coumarone resin; 15g of carbon black; 4g of diisononyl cyclohexane 1,2-dicarboxylate; 11g of hydroxylated carbon nanotubes, selected from the hydroxylated carbon nanotubes prepared in Preparation Example 2-1; 5g of softened ramie fiber was selected from the ramie fiber prepared in Preparation Example 4-1.

[0038] The preparation method of cold-resistant rubber includes the following steps: Nitrile rubber, acrylate rubber, and butadiene rubber are mixed in an internal mixer at a temperature of 80°C for 10 minutes. Other raw materials, excluding vulcanizing agents and accelerators, are added to the internal mixer and mixed at a temperature of 100°C for 5 minutes. After discharge, the mixture is cooled at room temperature for 24 hours and used as a base rubber for future use. The base rubber, accelerator, and vulcanizing agent are mixed evenly on a two-roll mill with a roll gap of 2 mm, a rolling temperature of 50°C, and a rolling time of 5 min. After being sheeted from the two-roll mill, the rubber is cooled to obtain cold-resistant rubber.

[0039] Example 2 A cold-resistant rubber, comprising the following raw materials: 55g of nitrile rubber, with an acrylonitrile content of 33% and a Mooney viscosity of 55, is graded Shunze 3355. 35g of acrylate rubber, selected from the acrylate rubber prepared in Preparation Example 3-2; 28g of butadiene rubber; purchased from Dongguan Shengli New Material Co., Ltd., model number XH03402GFPSN; 2g of vulcanizing agent, using 1g of sulfur and 1g of zinc oxide; 2.5g of accelerator, using 1g of accelerator CZ, 1g of accelerator NA-22 and 0.5g of accelerator NS; 3g of antioxidant, consisting of 2g of N-isopropyl-N'-phenyl-p-phenylenediamine and 1g of 2-thiol-benzimidazole; 1g of stearic acid; 0.6g of microcrystalline wax; 5g of coumarone resin; 23g of carbon black; 7g of diisononyl cyclohexane 1,2-dicarboxylate; 17g of hydroxylated carbon nanotubes, selected from the hydroxylated carbon nanotubes prepared in Preparation Example 2-1; 9g of softened ramie fiber was selected from the ramie fiber prepared in Preparation Example 4-2.

[0040] The preparation method of cold-resistant rubber includes the following steps: Nitrile rubber, acrylate rubber, and butadiene rubber are mixed in an internal mixer at a temperature of 100°C for 12 minutes. Other raw materials, excluding vulcanizing agents and accelerators, are added to the internal mixer and mixed at a temperature of 120°C for 10 minutes. After discharge, the mixture is cooled at room temperature for 24 hours and used as a base rubber for future use. The base rubber, accelerator, and vulcanizing agent are mixed evenly on a two-roll mill with a roll gap of 2 mm, a mixing temperature of 80℃, and a mixing time of 8 min. After being sheeted from the two-roll mill, the rubber is cooled to obtain cold-resistant rubber.

[0041] Example 3 A cold-resistant rubber, comprising the following raw materials: 47g of nitrile rubber, 33% acrylonitrile content, Mooney viscosity 55, grade Shunze 3355; 31g of acrylate rubber, selected from the acrylate rubber prepared in Preparation Example 3-1; 25g of butadiene rubber, purchased from Shandong Suihua Biotechnology Co., Ltd. 1.6g of vulcanizing agent, using dibenzenesulfonyl hydrazine ether; The accelerator was 2.3g, and 1.5g of accelerator DM and 0.8g of accelerator TT were selected. Antioxidant 2.5g, selected from 1.5g di-tert-butyl-p-cresol and 1g 2,2,4-trimethyl-1,2-dihydroquinoline polymer; Stearic acid 0.8g; Microcrystalline wax 0.4g; 4g of coumarone resin; 19g of carbon black; 6g of diisononyl cyclohexane 1,2-dicarboxylate; 14g of hydroxylated carbon nanotubes, selected from the hydroxylated carbon nanotubes prepared in Preparation Example 2-2; 8g of softened ramie fiber was selected from the ramie fiber prepared in Preparation Example 4-1.

[0042] The preparation method of cold-resistant rubber includes the following steps: Nitrile rubber, acrylate rubber, and butadiene rubber are mixed in an internal mixer at a temperature of 90°C for 10 minutes. Other raw materials, excluding vulcanizing agents and accelerators, are then added to the internal mixer and mixed at a temperature of 110°C for 8 minutes. After discharge, the mixture is cooled at room temperature for 24 hours and used as a base rubber for future use. The base rubber, accelerator, and vulcanizing agent are mixed evenly on a two-roll mill with a roll gap of 2 mm, a mixing temperature of 70℃, and a mixing time of 5 min. After being sheeted from the two-roll mill, the rubber is cooled to obtain cold-resistant rubber.

[0043] Example 4 The difference between this embodiment and Embodiment 1 is that the nitrile rubber in the cold-resistant rubber raw material is different.

[0044] In this embodiment, the nitrile rubber used is the polycaprolactone-grafted nitrile rubber obtained in Preparation Example 1-1.

[0045] Example 5 The difference between this embodiment and Embodiment 1 is that the nitrile rubber in the cold-resistant rubber raw material is different.

[0046] In this embodiment, the nitrile rubber used is the polycaprolactone-grafted nitrile rubber obtained in Preparation Examples 1-2.

[0047] Example 6 The difference between this embodiment and Embodiment 1 is that the acrylate rubber in the cold-resistant rubber raw material is different.

[0048] In this embodiment, the acrylic rubber used is commercially available acrylic rubber, specifically purchased from Dongguan Caihua Plastics Technology Co., Ltd., and the brand is Osaka Soda, Japan. Comparative Example

[0049] Comparative Example 1 The difference between this comparative example and Example 1 is that the raw materials for the cold-resistant rubber are different.

[0050] In this comparative example, no hydroxylated carbon nanotubes were added to the raw materials of the cold-resistant rubber.

[0051] Comparative Example 2 The difference between this comparative example and Example 1 is that the raw materials for the cold-resistant rubber are different.

[0052] In this comparative example, no softened ramie fiber was added to the raw materials of the cold-resistant rubber.

[0053] The following properties were tested on the cold-resistant rubbers prepared in Examples 1-6 and Comparative Examples 1-2, and the test results are shown in Table 1.

[0054] Tensile strength: Tested in accordance with GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber".

[0055] Resilience: The rebound rate is tested using the falling ball method. A steel ball of a certain mass is dropped from a certain height onto the rubber sample, and the rebound height of the steel ball is measured.

[0056] Cold resistance: expressed by brittle temperature, referring to GB / T 15256-2014 "Determination of low-temperature brittleness of vulcanized rubber or thermoplastic rubber". The test method is to cool the humidifier with dry ice, and after adjusting to the required low temperature, use a clamp to vertically insert the sample, keep it for 3 minutes and then take it out. Within 0.5 seconds, use an impactor to impact the sample and measure the highest temperature at which the sample cracks or breaks.

[0057] Table 1 Sample <![CDATA[Tensile strength (N / mm 2 )]]> Rebound rate (%) Brittleness temperature (°C) Example 1 23.5 53 -50.8 Example 2 24.3 55 -51.7 Example 3 23.8 51 -51.2 Example 4 25.7 56 -53.4 Example 5 25.5 55 -53.7 Example 6 21.2 48 -48.7 Comparative Example 1 18.7 50 -46.3 Comparative Example 2 19.1 48 -49.1 According to the data in Table 1, the cold-resistant rubbers prepared in Examples 1-5 of this application have a tensile strength > 23 MPa, a resilience of 50%-56%, and a temperature < -50℃. This demonstrates that the rubber foam material prepared in this application, using a specific ratio of nitrile rubber, nitrile rubber, and butadiene rubber as the resin matrix, and adding plasticizers and compound fillers (hydroxylated carbon nanotubes and softened ramie fibers), exhibits good low-temperature resistance and resilience after vulcanization, while ensuring a certain tensile strength, making it suitable for use in cold environments.

[0058] The cold-resistant rubbers of Examples 4-5 showed further improved performance compared to Example 1, indicating that introducing soft polycaprolactone segments into nitrile rubber with poor cold resistance can increase the molecular flexibility of the rubber molecular chain and further improve its cold resistance.

[0059] The performance of Example 6 decreased compared to Example 1, demonstrating that by selecting specific cold-resistant monomers and vulcanization point monomers, the cold resistance and mechanical strength of the acrylate rubber of this application can be improved.

[0060] Comparative Examples 1 and 2 modified the hydroxylated carbon nanotubes and softened ramie fibers used in this application, respectively. The data demonstrated the synergistic effect of the composite fillers in the cold-resistant rubber of this application, which can improve the cold resistance and mechanical properties of the rubber material.

[0061] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this specific embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A cold-resistant rubber, characterized in that, Including the following parts by weight of raw materials: 38-55 parts of nitrile rubber; 25-35 parts of nitrile rubber; 20-28 parts of butadiene rubber; 1.2-2 parts of vulcanizing agent; Accelerator 1.7-2.5 parts; Anti-aging agent 2-3 parts; Stearic acid 0.5-1 part; Microcrystalline wax 0.3-0.6 parts; 3-5 parts of coumarone resin; 15-23 parts carbon black; 4-7 parts of diisononyl cyclohexane 1,2-dicarboxylate; 11-17 parts of hydroxylated carbon nanotubes; Soften 5-9 parts of ramie fiber; The softened ramie fiber is selected from ramie fibers that have undergone low-temperature softening treatment with NaOH / urea / thiourea.

2. The cold-resistant rubber according to claim 1, characterized in that: The nitrile rubber is selected from polycaprolactone-grafted nitrile rubber and is prepared through the following steps: Add 10-15 parts by weight of nitrile rubber to tetrahydrofuran and stir to dissolve to obtain a rubber solution. Add 0.1-0.3 parts by weight of benzoyl peroxide to the rubber solution, and slowly add 7-12 parts by weight of caprolactone monomer to the solution. Heat to 70-90℃ and react for 4-8 hours under nitrogen protection. After the reaction was completed, the mixture was cooled to room temperature, and the reaction solution was slowly poured into a large amount of methanol to precipitate the product. The solid product was obtained by filtration, washed with methanol, and then dried under vacuum to obtain polycaprolactone-grafted nitrile rubber.

3. The cold-resistant rubber according to claim 1, characterized in that: The hydroxylated carbon nanotubes are prepared by the following steps: Carbon nanotubes were dissolved in deionized water, and the pH was adjusted to 3-4 with dilute hydrochloric acid. Under ultrasonic stirring, a mixture of hydrogen peroxide and ferrous chloride solution with a molar ratio of 10:1 was prepared and added dropwise to the carbon nanotube solution at a rate of 45-48 drops / min. The weight ratio of carbon nanotubes to the volume ratio of the mixture was 0.8-1.1:

200. The mixture was ultrasonically stirred for 4-6 hours, filtered, and dried to obtain hydroxylated carbon nanotubes.

4. The cold-resistant rubber according to claim 1, characterized in that: The acrylate rubber comprises the following raw materials in parts by weight: 55-70 parts of ethyl acrylate; 15-22 parts of methoxyethyl acrylate; 6-9 parts of methoxylated polyethylene glycol acrylate; Vinyl chloroacetate 2.5-4 parts.

5. The cold-resistant rubber according to claim 1, characterized in that: The softened ramie fiber is obtained through the following steps: The NaOH / urea / thiourea solution was cooled to -5 to 1°C in a cryogenic bath, wherein the mass concentration of the NaOH / urea / thiourea solution was: NaOH 7-8%, urea 8-10%, and thiourea 6.5-7.5%. The washed and degummed ramie fibers are immersed in a solution at a bath ratio of 1:10-20, stirred continuously for 15-20 minutes, then removed, washed with water, and dried at 60-80℃ to obtain softened ramie fibers.

6. The cold-resistant rubber according to claim 1, characterized in that: The vulcanizing agent is selected from one or more of sulfur, zinc oxide, and dibenzenesulfonyl hydrazine ether.

7. The cold-resistant rubber according to claim 1, characterized in that: The accelerator is selected from two or more of the following: accelerator DM, accelerator NS, accelerator CZ, accelerator NA-22, and accelerator TT.

8. The cold-resistant rubber according to claim 1, characterized in that: The antioxidant is selected from one or more of di-tert-butyl-p-cresol, 2-thiol-benzimidazole, N-isopropyl-N'-phenyl-p-phenylenediamine, and 2,2,4-trimethyl-1,2-dihydroquinoline polymers.

9. The cold-resistant rubber according to claim 1, characterized in that: The nitrile rubber has a Mooney viscosity of 45-65 and an acrylonitrile mass fraction of 25-43%.

10. A method for preparing a cold-resistant rubber according to any one of claims 1-9, characterized in that: Includes the following steps: Nitrile rubber, acrylate rubber, and butadiene rubber are mixed in an internal mixer at a temperature of 80-100℃ for 10-12 minutes. Other raw materials except vulcanizing agents and accelerators are added to the internal mixer and mixed at a temperature of 100-120℃ for 5-10 minutes. After discharge, the mixture is cooled at room temperature for 24 hours and used as a base rubber for future use. The base rubber, accelerator, and vulcanizing agent are mixed evenly on a two-roll mill at a temperature of 50-80℃ for 5-8 minutes. After being sheeted from the two-roll mill, the rubber is cooled to obtain cold-resistant rubber.