Low-temperature-resistant wear-resistant NBR composite material and preparation method and application thereof

Abstract

The invention relates to the technical field of NBR composite materials, in particular to a low-temperature-resistant wear-resistant NBR composite material and a preparation method and application thereof. The invention provides a low-temperature-resistant wear-resistant NBR (nitrile-butadiene rubber) composite material, which is prepared from the following components in parts by mass: 100 parts of NBR raw rubber, 2 to 6 parts of zinc oxide, 0.5 to 2 parts of stearic acid, 30 to 80 parts of carbon black, 1 to 3 parts of 2-mercaptobenzimidazole, 2 to 12 parts of oleylamine grafted halloysite nanotubes, 0.5 to 2 parts of sulfur and 0.5 to 4 parts of N-cyclohexyl-2-benzothiazole sulfenamide. According to the low-temperature-resistant wear-resistant NBR composite material, the compatibility of the additive and the NBR raw rubber is good, and the blooming phenomenon is avoided.

Description

Technical Field

[0001] This invention relates to the field of NBR composite material technology, and in particular to a low-temperature resistant and wear-resistant NBR composite material, its preparation method, and its application. Background Technology

[0002] Currently, there are two common approaches to improve the low-temperature resistance of NBR materials: one is to select NBR with a low Tg, and the other is to add cold-resistant plasticizers that can significantly reduce the Tg of NBR vulcanizates. Adding cold-resistant plasticizers is economical and efficient; however, due to the poor compatibility between small-molecule rubber cold-resistant plasticizers and rubber, blooming can easily occur in the rubber when a large amount is added. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a low-temperature wear-resistant NBR composite material, its preparation method and application, wherein the additives in the low-temperature wear-resistant NBR composite material have good compatibility with NBR raw rubber and will not exhibit blooming phenomenon.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a low-temperature resistant and wear-resistant NBR composite material, comprising, by weight, 100 parts of NBR raw rubber, 2-6 parts of zinc oxide, 0.5-2 parts of stearic acid, 30-80 parts of carbon black, 1-3 parts of 2-mercaptobenzimidazole, 2-12 parts of oleylamine-grafted halloysite nanotubes, 0.5-2 parts of sulfur, and 0.5-4 parts of N-cyclohexyl-2-benzothiazole sulfenamide.

[0005] Preferably, the method for preparing the oleylamine-grafted halloysite nanotubes includes the following steps: The oleylamine and epoxysilane coupling agent were mixed, refluxed, and then mixed with an aqueous ethanol solution for hydrolysis to obtain an intermediate product. The intermediate product and halloysite nanotube (HNT) dispersion were mixed and grafted to obtain the oleylamine-grafted halloysite nanotubes.

[0006] Preferably, the molar ratio of oleylamine to epoxysilane coupling agent is 1:(0.5~1.5).

[0007] Preferably, the reflux temperature is 50~80℃ and the time is 4~10h.

[0008] Preferably, the mass concentration of the ethanol aqueous solution is 50% to 95%; The hydrolysis time is 20-60 minutes.

[0009] Preferably, the mass concentration of the halloysite nanotube dispersion is 0.5% to 5%; The molar ratio of halloysite nanotubes to intermediate products in the halloysite nanotube dispersion is 1:(1~5).

[0010] Preferably, the grafting is performed under stirring conditions; The grafting temperature is 20~50℃, and the grafting time is 6~12h.

[0011] This invention also provides a method for preparing the low-temperature resistant and wear-resistant NBR composite material described in the above technical solution, comprising the following steps: After plasticizing NBR raw rubber, zinc oxide, stearic acid, carbon black, 2-mercaptobenzimidazole and the oleylamine-grafted halloysite nanotubes are added and mixed to obtain nitrile rubber compound. The nitrile rubber compound, sulfur, and N-cyclohexyl-2-benzothiazole sulfenamide are mixed and then successively wrapped in triangular bundles and rolled to obtain a compound calender sheet. The compound rubber calendered sheet is vulcanized to obtain the low-temperature resistant NBR composite material.

[0012] Preferably, the vulcanization temperature is 130~170℃, the pressure is 5~15MPa, and the time is 10~50min.

[0013] This invention also provides the application of the low-temperature wear-resistant NBR composite material described in the above technical solution or the low-temperature wear-resistant NBR composite material prepared by the preparation method described in the above technical solution in the automotive industry, petrochemical industry and hydraulic machinery field.

[0014] This invention provides a low-temperature resistant and wear-resistant NBR composite material, comprising, by weight parts: 100 parts NBR raw rubber, 2-6 parts zinc oxide, 0.5-2 parts stearic acid, 30-80 parts carbon black, 1-3 parts 2-mercaptobenzimidazole, 2-12 parts oleylamine-grafted halloysite nanotubes, 0.5-2 parts sulfur, and 0.5-4 parts N-cyclohexyl-2-benzothiazole sulfenamide. This invention grafts oleylamine onto HNTs to prepare a composite rubber modifier with good compatibility, and modifies the nitrile butadiene rubber composite material to have good compatibility with rubber, resulting in the NBR composite material exhibiting excellent low-temperature resistance and wear resistance. Attached Figure Description

[0015] Figure 1 This is a SEM image of HNTs and HNTs-Y as described in the embodiments of the present invention. Detailed Implementation

[0016] This invention provides a low-temperature resistant and wear-resistant NBR composite material, comprising, by weight, 100 parts of NBR raw rubber, 2-6 parts of zinc oxide, 0.5-2 parts of stearic acid, 30-80 parts of carbon black, 1-3 parts of 2-mercaptobenzimidazole, 2-12 parts of oleylamine-grafted halloysite nanotubes, 0.5-2 parts of sulfur, and 0.5-4 parts of N-cyclohexyl-2-benzothiazole sulfenamide.

[0017] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0018] The low-temperature resistant and wear-resistant NBR composite material of the present invention comprises 100 parts of NBR raw rubber by weight.

[0019] Based on the mass fraction of the NBR raw rubber, the low-temperature resistant and wear-resistant NBR composite material of the present invention comprises 2 to 6 parts of zinc oxide, more preferably 2, 3, 4, 5, or 6 parts. In an embodiment of the present invention, the mass fraction of zinc oxide can be 5 parts.

[0020] In this invention, the zinc oxide acts as the main activator of the vulcanization system. On one hand, it synergistically forms soluble zinc soap with stearic acid, activating accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide and accelerating the cross-linking reaction between sulfur and NBR molecular chains. On the other hand, it can slightly interact with the hydroxyl and amino groups on the surface of oleylamine-grafted halloysite nanotubes, assisting their dispersion in the NBR matrix and reducing graft aggregation. The advantage of controlling the amount of zinc oxide within the above range is that when it is less than 2 parts, the activation efficiency is insufficient, the vulcanization speed is slow and the cross-linking is incomplete. The oleylamine-grafted halloysite nanotubes are prone to forming local weak points due to poor dispersibility, resulting in a decrease in rubber wear resistance. When it is more than 6 parts, excess zinc oxide is prone to excessive binding with the amino groups on the surface of oleylamine-grafted halloysite nanotubes, which can lead to graft aggregation and precipitation on the rubber surface (blooming), damaging low-temperature elasticity and surface integrity.

[0021] Based on the mass fraction of the NBR raw rubber, the low-temperature resistant and wear-resistant NBR composite material of the present invention comprises 0.5 to 2 parts of stearic acid, more preferably 0.5 parts, 1 part, 1.5 parts, or 2 parts. In the embodiments of the present invention, the mass fraction of the stearic acid can be 1 part.

[0022] In this invention, stearic acid serves a dual function as both an auxiliary activator and a dispersing lubricant. As an auxiliary activator, it reacts with zinc oxide to form zinc soap, enhancing vulcanization activity. As a lubricant, it reduces the frictional resistance during mixing of oleylamine-grafted halloysite nanotubes with NBR raw rubber and carbon black, helping the grafted material to disperse evenly. Simultaneously, it improves the flowability of the rubber compound during processing, preventing adhesion to the mold during vulcanization. The advantage of controlling the amount of stearic acid within the aforementioned range is that below 0.5 parts, the oleylamine-grafted halloysite nanotubes are prone to agglomeration due to high dispersion resistance, resulting in weak vulcanization activation and easy mold adhesion. Above 2 parts, excessive stearic acid forms a "coating layer" on the surface of the oleylamine-grafted halloysite nanotubes, hindering their bonding with the NBR molecular chains and potentially migrating to the rubber surface, causing blooming and reducing oil resistance and the reinforcing effect of HNTs-oleylamine.

[0023] Based on the mass fraction of the NBR raw rubber, the low-temperature resistant and wear-resistant NBR composite material of the present invention comprises 30 to 80 parts of carbon black, more preferably 30, 40, 50, 60, 70, or 80 parts. In an embodiment of the present invention, the mass fraction of the carbon black may be 40 parts.

[0024] In this invention, the carbon black is preferably one or more of carbon black N220, carbon black N219, carbon black N231, and carbon black N234. When the carbon black is two or more of the above-mentioned specific selections, this invention does not impose any special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio. In an embodiment of this invention, the carbon black can be carbon black N220.

[0025] In this invention, the carbon black acts as the primary reinforcing agent, forming a "dual reinforcing system" with the HNTs-oleylamine graft. Carbon black enhances the mechanical strength and abrasion resistance of the rubber through particle filling, while the oleylamine-grafted halloysite nanotubes improve the rubber's tear resistance and low-temperature toughness due to their tubular structure. Simultaneously, the high specific surface area of ​​carbon black adsorbs oleylamine molecules on the surface of the oleylamine-grafted halloysite nanotubes, further inhibiting graft aggregation and synergistically optimizing the overall performance of the rubber. The advantage of controlling the amount of carbon black within the aforementioned range is that when it is below 30 parts, the reinforcing effect of a single oleylamine-grafted halloysite nanotube is limited, resulting in insufficient tensile strength and abrasion resistance of the rubber; when it is above 80 parts, carbon black will crowd out the dispersion space of the oleylamine-grafted halloysite nanotubes, causing both to aggregate, leading to a sharp drop in the rubber's low-temperature elasticity, increased mixing difficulty, and increased brittleness of the rubber compound.

[0026] Based on the mass fraction of the NBR raw rubber, the low-temperature resistant and wear-resistant NBR composite material of the present invention includes 1 to 3 parts of 2-mercaptobenzimidazole, more preferably 1 part, 1.5 parts, 2 parts, 2.5 parts or 3 parts.

[0027] In this invention, the 2-mercaptobenzimidazole acts as an antioxidant, preferentially reacting with oxidative free radicals generated during rubber aging. This protects the NBR molecular chains and the amine structure of the oleylamine-grafted halloysite nanotubes from oxidative damage, extending the service life of the vulcanizate under low-temperature friction conditions. The advantage of controlling the amount of 2-mercaptobenzimidazole within the aforementioned range is that: below 1 part, the antioxidant effect is weak, and the amine groups of the oleylamine-grafted halloysite nanotubes are easily oxidized and degraded, leading to a decrease in the bonding force between the graft and the rubber matrix and a rapid decline in wear resistance; above 3 parts, excessive antioxidant will compete with the oleylamine-grafted halloysite nanotubes for adsorption on the carbon black surface, disrupting the "carbon black-graft" synergistic dispersion system and potentially causing blooming, affecting the rubber's appearance and low-temperature resistance.

[0028] Based on the mass fraction of the NBR raw rubber, the low-temperature resistant and wear-resistant NBR composite material of the present invention includes 0.5 to 2 parts of sulfur, more preferably 0.5 parts, 1 part, 1.5 parts or 2 parts.

[0029] In this invention, the sulfur acts as a vulcanizing agent, forming cross-linking bonds (sulfur bonds) with the NBR molecular chains under the action of an accelerator, transforming the linear raw rubber into a three-dimensional network structure. Simultaneously, it can undergo a slight cross-linking reaction with the amine groups on the surface of the oleylamine-grafted halloysite nanotubes, enhancing the bonding force between the graft and the NBR matrix, allowing the tubular graft to be more stably embedded in the rubber network, thus improving wear resistance and low-temperature crack resistance. The advantage of controlling the amount of sulfur within the above-mentioned range is that: below 0.5 parts, the cross-linking density is too low, the NBR network is loose, and the oleylamine-grafted halloysite nanotubes are easily detached during friction, resulting in poor rubber strength and wear resistance; above 2 parts, excessive cross-linking increases the rigidity of the rubber molecular chains, leading to loss of low-temperature elasticity (increased embrittlement temperature), and excess sulfur will cover the surface of the oleylamine-grafted halloysite nanotubes, weakening their tubular reinforcing effect.

[0030] Based on the mass fraction of the NBR raw rubber, the low-temperature resistant and wear-resistant NBR composite material of the present invention includes 0.5 to 4 parts of N-cyclohexyl-2-benzothiazole sulfenamide, more preferably 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts or 4 parts.

[0031] In this invention, the N-cyclohexyl-2-benzothiazole sulfenamide acts as a post-curing accelerator, inhibiting the early reaction between sulfur and NBR at low temperatures (preventing scorching) and ensuring that the oleylamine-grafted halloysite nanotubes are fully dispersed during compounding. At high temperatures, it rapidly releases active groups, accelerating sulfur crosslinking and adjusting the type of crosslinking bonds (increasing the ratio of monosulfide and disulfide bonds). This ensures sufficient low-temperature elasticity while maintaining rubber strength. The advantage of controlling the amount of N-cyclohexyl-2-benzothiazole sulfenamide within the above range is that: below 0.5 parts, the curing speed is slow, crosslinking is insufficient, and the oleylamine-grafted halloysite nanotubes are not firmly bonded to the rubber; above 4 parts, the curing reaction is too fast, the crosslinking density is too high, the rubber becomes hard and brittle, the tubular structure of the oleylamine-grafted halloysite nanotubes cannot exert its toughness advantage, and uneven local crosslinking is easily triggered, leading to fluctuations in wear resistance.

[0032] Based on the mass fraction of the NBR raw rubber, the low-temperature resistant and wear-resistant NBR composite material of the present invention includes 2 to 12 parts of oleylamine-grafted halloysite nanotubes, more preferably 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 parts.

[0033] In this invention, the method for preparing the oleylamine-grafted halloysite nanotubes preferably includes the following steps: The oleylamine and epoxysilane coupling agent were mixed, refluxed, and then mixed with an aqueous ethanol solution for hydrolysis to obtain an intermediate product. The intermediate product and halloysite nanotube dispersion were mixed and grafted to obtain the oleylamine-grafted halloysite nanotubes.

[0034] In this invention, the preparation process of the oleylamine-grafted halloysite nanotubes is shown in Formula 1: Formula 1.

[0035] In this invention, oleylamine and an epoxy silane coupling agent are mixed, refluxed, and then mixed with an aqueous ethanol solution for hydrolysis to obtain an intermediate product.

[0036] In this invention, the molar ratio of oleylamine to epoxy silane coupling agent is preferably 1:(0.5~1.5), more preferably 1:0.5, 1:0.8, 1:1, 1:1.3 or 1:1.5.

[0037] In this invention, the epoxy silane coupling agent is preferably KH560.

[0038] The present invention does not impose any special limitations on the mixing process; any process known to those skilled in the art can be used.

[0039] In this invention, the stirring is preferably carried out under stirring conditions; the reflux temperature is preferably 50~80℃, more preferably 50℃, 60℃, 70℃ or 80℃; the time is preferably 4~10h, more preferably 4h, 5h, 6h, 7h, 8h, 9h or 10h. In an embodiment of this invention, the reflux temperature can be 60℃ and the time is 5h. In an embodiment of this invention, the reflux temperature is preferably achieved using an oil bath.

[0040] After the reflux is completed, the present invention preferably includes cooling, wherein the cooling time is preferably 20-60 min, more preferably 20 min, 30 min, 40 min, 50 min or 60 min; and the temperature after cooling is preferably 15-35℃, more preferably 15℃, 20℃, 25℃, 30℃ or 35℃.

[0041] In this invention, the mass concentration of the ethanol aqueous solution is preferably 50% to 95%, more preferably 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or 95%.

[0042] In this invention, the hydrolysis is preferably carried out under ultrasonic conditions, and the hydrolysis temperature is preferably 15~35℃, more preferably 15℃, 20℃, 25℃, 30℃ or 35℃; the hydrolysis time is preferably 20~60min, more preferably 20min, 30min, 40min, 50min or 60min. In an embodiment of this invention, the hydrolysis temperature can be 25℃ and the time can be 40min.

[0043] In this invention, the silane coupling agent generally has the general formula YR-Si(OR)3, where OR is a hydrolyzable alkoxy group. During the hydrolysis process, the alkoxy group of the silane coupling agent is hydrolyzed to generate silanol, which then forms a stable Si-O-Si bond with the hydroxyl groups on the surface of halloysite nanotubes through a condensation reaction, thereby grafting the silane coupling agent onto the surface of the halloysite nanotubes.

[0044] After obtaining the intermediate product, the present invention mixes the intermediate product with halloysite nanotube dispersion and grafts it to obtain the oleylamine-grafted halloysite nanotubes.

[0045] In this invention, the mass concentration of the halloysite nanotube (HNT) dispersion is preferably 0.5% to 5%, more preferably 0.5%, 1%, 2%, 3%, 4%, or 5%. In an embodiment of this invention, the mass concentration of the halloysite nanotube dispersion can be 3%.

[0046] In this invention, the method for preparing the halloysite nanotube dispersion preferably includes: The halloysite nanotubes were mixed with an aqueous ethanol solution to obtain the halloysite nanotube dispersion.

[0047] In this invention, the mass concentration of the ethanol aqueous solution is preferably 50% to 95%, more preferably 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or 95%.

[0048] In this invention, the mixing is preferably performed under ultrasonic conditions, and the ultrasonic time is preferably 20 to 60 minutes, more preferably 20 minutes, 30 minutes, 40 minutes, 50 minutes or 60 minutes.

[0049] In this invention, the surface of the Holstein nanotubes (HNTs) naturally contains hydroxyl groups, mainly including two types: silanol (-Si-OH) and aluminumol (-Al-OH). These hydroxyl groups originate from their crystal structure: as a 1:1 type aluminosilicate, its molecular structure inherently contains hydroxyl groups, and at crystal edges, interlayers, and other positions, incompletely bonded silicon and aluminum atoms combine with hydrogen to form hydroxyl groups, becoming important active sites on its surface, which can undergo condensation reactions with the hydrolysis products of silane coupling agents.

[0050] In this invention, the molar ratio of halloysite nanotubes to intermediate products in the halloysite nanotube dispersion is preferably 1:(1~5), more preferably 1:1, 1:2, 1:3, 1:4 or 1:5. In an embodiment of this invention, the molar ratio of halloysite nanotubes to intermediate products in the halloysite nanotube dispersion can be 1:1.

[0051] In this invention, the grafting is preferably carried out under stirring conditions, the grafting method is preferably reflux, the temperature of the medium is preferably 20~50℃, more preferably 20℃, 30℃, 40℃ or 50℃, and the time is preferably 6~12h, more preferably 6h, 7h, 8h, 9h, 10h, 11h or 12h.

[0052] After the grafting is completed, the present invention preferably includes cooling, the cooling time of which is preferably 20-60 minutes, more preferably 20 minutes, 30 minutes, 40 minutes, 50 minutes or 60 minutes. The temperature after cooling is preferably 15-35°C, more preferably 15°C, 20°C, 25°C, 30°C or 35°C.

[0053] After cooling, the present invention preferably includes sequentially performing filtration, washing, drying, and grinding; the filtration is preferably performed using a vacuum pump and Buchner funnel; the washing agent is preferably ethanol, and the present invention does not have any special limitation on the number of washings, as long as a number of times known to those skilled in the art is used and the filtrate is made clear; the drying method is preferably oven drying, and the drying temperature is preferably 60~90℃; the present invention does not have any special limitation on the grinding process, as long as a process known to those skilled in the art is used and the grinding is made into powder.

[0054] This invention grafts oleylamine onto HNTs to prepare a composite rubber modifier with good compatibility, and modifies the nitrile butadiene rubber composite material to have good compatibility with rubber, so that the NBR composite material has excellent low temperature resistance and wear resistance.

[0055] This invention also provides a method for preparing the low-temperature resistant and wear-resistant NBR composite material described in the above technical solution, comprising the following steps: After plasticizing NBR raw rubber, zinc oxide, stearic acid, carbon black, 2-mercaptobenzimidazole and the oleylamine-grafted halloysite nanotubes are added and mixed to obtain nitrile rubber compound. The nitrile rubber compound, sulfur, and N-cyclohexyl-2-benzothiazole sulfenamide are mixed and then successively wrapped in triangular bundles and rolled to obtain a compound calender sheet. The compound rubber calendered sheet is vulcanized to obtain the low-temperature resistant NBR composite material.

[0056] This invention involves plasticizing NBR raw rubber, then adding zinc oxide, stearic acid, carbon black, 2-mercaptobenzimidazole, and oleylamine-grafted halloysite nanotubes for compounding to obtain nitrile rubber compound.

[0057] In this invention, the preferred plasticizing process involves preheating the internal mixer before adding NBR raw rubber for plasticizing. The preheating temperature is preferably 20-50°C, more preferably 20°C, 30°C, 40°C, or 50°C. This invention does not impose any specific limitations on the plasticizing process; any process well-known to those skilled in the art can be used, provided that the purpose of wrapping the raw rubber around the roller is achieved.

[0058] In this invention, the process of adding zinc oxide, stearic acid, carbon black, 2-mercaptobenzimidazole and the oleylamine-grafted halloysite nanotubes is preferably carried out in the following order: zinc oxide, stearic acid, carbon black, 2-mercaptobenzimidazole and the oleylamine-grafted halloysite nanotubes.

[0059] In this invention, the mixing temperature is preferably 30~70℃, more preferably 30℃, 40℃, 50℃, 60℃ or 70℃; the mixing time is preferably 10~40min, more preferably 10min, 20min, 30min or 40min.

[0060] After the mixing is completed, the present invention preferably includes a settling period, wherein the settling temperature is preferably room temperature, and the settling time is preferably 24-48h, more preferably 24h, 26h, 28h, 30h, 32h, 34h, 36h, 38h, 40h, 42h, 44h, 46h or 48h.

[0061] After obtaining the nitrile rubber compound, the present invention mixes the nitrile rubber compound, sulfur and N-cyclohexyl-2-benzothiazole sulfenamide, and sequentially performs triangular wrapping and rolling to obtain a compound calender sheet.

[0062] In this invention, the mixing is preferably carried out by placing the nitrile rubber compound in a two-roll mill and adding sulfur and N-cyclohexyl-2-benzothiazole sulfenamide in sequence.

[0063] In this invention, the number of times the triangular patch is applied is preferably 2 to 5 times, more preferably 2, 3, 4 or 5 times; this invention does not impose any special limitations on the specific process of applying the triangular patch, and any process known to those skilled in the art can be used.

[0064] In this invention, the number of times the rolling is preferably 2 to 5 times, more preferably 2, 3, 4 or 5 times, with a pressure of 5 to 15 MPa; this invention does not impose any special limitations on the specific rolling process, and any process known to those skilled in the art can be used.

[0065] After the rolling is completed, the present invention preferably includes a resting period, wherein the resting temperature is preferably room temperature and the resting time is preferably 24~48h, more preferably 24h, 26h, 28h, 30h, 32h, 34h, 36h, 38h, 40h, 42h, 44h, 46h or 48h.

[0066] After obtaining the compound rubber calendered sheet, the present invention vulcanizes the compound rubber calendered sheet to obtain the low-temperature resistant NBR composite material.

[0067] In this invention, the vulcanization temperature is preferably 130~170℃, more preferably 130℃, 140℃, 150℃, 160℃ or 170℃; the pressure is preferably 5~15MPa, more preferably 5MPa, 6MPa, 7MPa, 8MPa, 9MPa, 10MPa, 11MPa, 12MPa, 13MPa, 14MPa or 15MPa; the time is preferably 10~50min, more preferably 10min, 20min, 30min, 40min or 50min. In this invention, the vulcanization is preferably carried out in a flat vulcanizing machine.

[0068] This invention also provides applications of the low-temperature wear-resistant NBR composite material described in the above-described technical solutions or the low-temperature wear-resistant NBR composite material prepared by the preparation method described in the above-described technical solutions in the automotive industry, petrochemical industry, and hydraulic machinery field. In this invention, the automotive industry application is preferably for engine oil seals, fuel liners, or transmission seals in low-temperature environments; the petrochemical industry application is preferably for the inner layer or sealing gasket of oil hoses in low-temperature oil depots or cold-region oil fields; and the hydraulic machinery application is preferably for hydraulic system seals or O-rings in loaders and excavators. This invention does not impose any special limitations on the methods used in these applications; methods well-known to those skilled in the art can be employed.

[0069] Example 1 26.7 g of oleylamine and 23.6 g of KH-560 silane coupling agent were added to a round-bottom flask at a molar ratio of 1:1. The mixture was heated under reflux in an oil bath at 60 °C for 5 h with stirring, cooled for 30 min, and then 80 g of 95% ethanol aqueous solution was added for hydrolysis (ultrasonication for 30 min) to obtain the alcoholyzed oleylamine coupling agent (Y). 29.4 g of HNTs were added to a 95% ethanol aqueous solution and mixed (ultrasonic treatment for 30 min) to obtain an HNTs dispersion. The HNTs dispersion and Y were mixed evenly (the molar ratio of HNTs to Y was 1:1), stirred and refluxed at 30°C for 8 hours, cooled for 30 minutes, and then filtered by vacuum pump Buchner funnel. The mixture was washed several times with ethanol until the filtrate was clear, dried at 80°C, and ground into powder to obtain oleylamine-grafted halloysite nanotubes (HNTs-Y). After preheating the internal mixer to 40°C, 100g of NBR raw rubber was added and plasticized until the raw rubber wrapped the rollers. Then, 5g of zinc oxide, 1g of stearic acid, 40g of carbon black N220, 1g of 2-mercaptobenzimidazole and 2g of HNTs-Y were added to the internal mixer in sequence and mixed for 20min. The mixed rubber was taken out of the internal mixer and allowed to stand at room temperature for 24h to obtain nitrile rubber compound. The nitrile rubber compound was placed in a two-roll mill, and 1.5g of sulfur and 1g of N-cyclohexyl-2-benzothiazole sulfenamide were added in sequence. The mixture was then rolled into a triangular shape three times and rolled three times before being extruded into a sheet. The resulting rubber sheet was left to stand at room temperature for 24 hours to obtain a calendered sheet of the compound. The compounded rubber calendered sheet was placed in a mold and placed in a flat vulcanizing machine for vulcanization (150℃, 10MPa, 40min) to obtain a low-temperature resistant and wear-resistant NBR composite material. Figure 1 Here are the SEM images of HNTs and HNTs-Y, where (a1)~(a2) are SEM images of HNTs at different magnifications, and (b1)~(b2) are SEM images of HNTs-Y at different magnifications. Figure 1 It can be seen that, Figure 1 The HNTs in (a1) to (a2) exhibit dispersed and relatively independent nanotube structures that are intertwined and somewhat aggregated, with a clear overall morphology that shows nanotube characteristics. Figure 1 The original independent tubular morphology of HNTs in (b1)~(b2) is "wrapped" and fused, the surface becomes rough and there is obvious plasticizer matrix attached. HNTs are dispersed in the continuous phase formed by oleylamine, no longer in the relatively free dispersion state in (a1)~(a2). The interface between the two is blurred, indicating that a grafting reaction occurs between halloysite nanotubes and plasticizer. The nanotubes are successfully grafted into the plasticizer system and chemical bonding is achieved. The significant change in micromorphology can prove that the grafting reaction occurred.

[0070] Example 2 Referring to Example 1, the difference is that the amount of HNTs-Y used is 4g, resulting in a low-temperature resistant and wear-resistant NBR composite material.

[0071] Example 3 Referring to Example 1, the difference is that the amount of HNTs-Y used is 6g, resulting in a low-temperature resistant and wear-resistant NBR composite material.

[0072] Comparative Example 1 Referring to Example 1, the difference is that the preparation process of oleylamine-grafted halloysite nanotubes is not included, and the oleylamine-grafted halloysite nanotubes are replaced with oleylamine to obtain NBR composite material.

[0073] Comparative Example 2 Referring to Example 2, the difference is that the preparation process of oleylamine-grafted halloysite nanotubes is not included, and the oleylamine-grafted halloysite nanotubes are replaced with oleylamine to obtain NBR composite material.

[0074] Comparative Example 3 Referring to Example 3, the difference is that the preparation process of oleylamine-grafted halloysite nanotubes is not included, and the oleylamine-grafted halloysite nanotubes are replaced with oleylamine to obtain NBR composite material.

[0075] Comparative Example 4 Referring to Example 1, the difference is that the preparation process of oleylamine-grafted halloysite nanotubes is not included, and the addition of oleylamine-grafted halloysite nanotubes is omitted, resulting in an NBR composite material.

[0076] The performance parameters of the low-temperature resistant and wear-resistant NBR composite materials described in Examples 1-3 and the NBR composite materials described in Comparative Examples 1-4 are shown in Table 1: Table 1 Performance parameters of the low-temperature resistant and wear-resistant NBR composite materials described in Examples 1-3 and the NBR composite materials described in Comparative Examples 1-4

[0077] As shown in Table 1, within a certain range, the addition of HNTs-Y can improve the tensile strength of NBR at low temperatures, reduce low-temperature brittleness, lower the glass transition temperature, reduce Akron abrasion, and effectively improve the low-temperature and cold-resistant properties of NBR.

[0078] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A low-temperature resistant and wear-resistant NBR composite material, characterized in that, The composition, by weight, includes 100 parts NBR raw rubber, 2-6 parts zinc oxide, 0.5-2 parts stearic acid, 30-80 parts carbon black, 1-3 parts 2-mercaptobenzimidazole, 2-12 parts oleylamine-grafted halloysite nanotubes, 0.5-2 parts sulfur, and 0.5-4 parts N-cyclohexyl-2-benzothiazole sulfenamide.

2. The low-temperature resistant and wear-resistant NBR composite material as described in claim 1, characterized in that, The method for preparing the oleylamine-grafted halloysite nanotubes includes the following steps: The oleylamine and epoxysilane coupling agent were mixed, refluxed, and then mixed with an aqueous ethanol solution for hydrolysis to obtain an intermediate product. The intermediate product and halloysite nanotube dispersion were mixed and grafted to obtain the oleylamine-grafted halloysite nanotubes.

3. The low-temperature resistant and wear-resistant NBR composite material as described in claim 2, characterized in that, The molar ratio of oleylamine to epoxysilane coupling agent is 1:(0.5~1.5).

4. The low-temperature resistant and wear-resistant NBR composite material as described in claim 2, characterized in that, The reflux temperature is 50~80℃, and the time is 4~10h.

5. The low-temperature resistant and wear-resistant NBR composite material as described in claim 2 or 4, characterized in that, The mass concentration of the ethanol aqueous solution is 50%~95%; The hydrolysis time is 20-60 minutes.

6. The low-temperature resistant and wear-resistant NBR composite material as described in claim 2, characterized in that, The mass concentration of the halloysite nanotube dispersion is 0.5%~5%; The molar ratio of halloysite nanotubes to intermediate products in the halloysite nanotube dispersion is 1:(1~5).

7. The low-temperature resistant and wear-resistant NBR composite material as described in claim 2, characterized in that, The grafting was carried out under stirring conditions; The grafting temperature is 20~50℃, and the grafting time is 6~12h.

8. The method for preparing the low-temperature resistant and wear-resistant NBR composite material according to any one of claims 1 to 7, characterized in that, Includes the following steps: After plasticizing NBR raw rubber, zinc oxide, stearic acid, carbon black, 2-mercaptobenzimidazole and the oleylamine-grafted halloysite nanotubes are added and mixed to obtain nitrile rubber compound. The nitrile rubber compound, sulfur, and N-cyclohexyl-2-benzothiazole sulfenamide are mixed and then successively wrapped in triangular bundles and rolled to obtain a compound calender sheet. The compound rubber calendered sheet is vulcanized to obtain the low-temperature resistant NBR composite material.

9. The preparation method according to claim 8, characterized in that, The vulcanization temperature is 130~170℃, the pressure is 5~15MPa, and the time is 10~50min.

10. The application of the low-temperature wear-resistant NBR composite material according to any one of claims 1 to 7 or the low-temperature wear-resistant NBR composite material prepared by the preparation method according to claim 8 or 9 in the automotive industry, petrochemical industry and hydraulic machinery field.

Images