Anti-static nitrile rubber and preparation method thereof

Abstract

The invention relates to the technical field of nitrile rubber, and discloses antistatic nitrile rubber and a preparation method thereof. The antistatic nitrile rubber is prepared from the following raw materials in parts by weight: 100 parts of nitrile rubber, 1-7 parts of an active agent, 15-50 parts of a filling reinforcing agent, 1-2 parts of an anti-aging agent, 2-15 parts of a softening agent, 2-6 parts of an antistatic agent, 1.5-2.0 parts of a vulcanizing agent, 1-3 parts of an accelerant and 0.5-3 parts of a conductive reinforcing agent, the preparation method comprises the following steps: S1, pre-treating the compound; S2, mixing the main materials; S3, discharging rubber and plasticizing; S4, adding a vulcanization system; according to the anti-static nitrile rubber disclosed by the invention, the conductive enhancer is combined with the graphene oxide and polyaniline compound, so that a conductive network is cooperatively constructed in a nitrile rubber matrix; therefore, the problems that the antistatic property is degraded and the mechanical property is damaged due to the fact that the bonding force of a single conductive filler and a rubber matrix interface is weak and a conductive network is easy to break in the traditional antistatic nitrile rubber are solved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of nitrile rubber, in particular to an antistatic nitrile rubber and a preparation method thereof. BACKGROUND

[0002] The antistatic nitrile rubber is a synthetic rubber material with antistatic performance and excellent physical and mechanical properties. The antistatic nitrile rubber is prepared by adding conductive fillers, antistatic agents and other additives to nitrile rubber as a matrix and then mixing and vulcanizing through a special process. The nitrile rubber has high acrylonitrile content, excellent oil resistance, resistance to invasion of various oils such as gasoline and lubricating oil, and good wear resistance and aging resistance. The rubber is widely used in the electronic manufacturing field to make antistatic gloves and turnover boxes to prevent precise electronic components from being damaged by static electricity; in the petrochemical industry, the rubber can be made into antistatic rubber pipes and sealing gaskets to prevent static electricity from causing fire and explosion; and in the aerospace field, the rubber is used to manufacture antistatic floors and interior materials to ensure the safe operation of equipment.

[0003] According to the related technology in the above, the inventors believe that the antistatic nitrile rubber mostly uses a single conductive filler, and the interface bonding force between the filler and the rubber matrix is weak and the conductive path is easy to break, thereby causing the problem of attenuation of antistatic performance and damage to mechanical properties. SUMMARY

[0004] In order to solve the problem that the antistatic nitrile rubber mostly uses a single conductive filler, and the interface bonding force between the filler and the rubber matrix is weak and the conductive path is easy to break, thereby causing the problem of attenuation of antistatic performance and damage to mechanical properties, the application provides an antistatic nitrile rubber and a preparation method thereof.

[0005] In the first aspect, the application provides an antistatic nitrile rubber, which adopts the following technical scheme:

[0006] The antistatic nitrile rubber comprises the following raw materials in parts by weight: nitrile rubber 100 parts, active agent 1-7 parts, filling and reinforcing agent 15-50 parts, antioxidant 1-2 parts, softening agent 2-15 parts, antistatic agent 2-6 parts, vulcanizing agent 1.5-2.0 parts, accelerator 1-3 parts and conductive reinforcing agent 0.5-3 parts; the antistatic agent is a graphene oxide and polyaniline composite.

[0007] By adopting the technical scheme, the specific weight parts of raw materials including nitrile raw rubber, active agent, filling and reinforcing agent, antioxidant, softening agent, graphene oxide and polyaniline complex antistatic agent, vulcanizing agent, accelerator and conductive reinforcing agent are used, the conductive reinforcing agent is combined with the graphene oxide and polyaniline complex, and then a conductive network is constructed in the nitrile rubber matrix, so that the problem that the traditional antistatic nitrile rubber mostly uses a single conductive filler, the interface bonding force between the filler and the rubber matrix is weak, and the conductive path is easy to break, thereby causing the problems of insufficient durability of antistatic performance and damaged mechanical properties is solved.

[0008] Preferably, the conductivity of the antistatic agent at 25℃±2℃ under a pressure of 10MPa is 10 -4 ~ 10 -1 S / cm.

[0009] By adopting the technical scheme, the graphene oxide and polyaniline complex with a conductivity of 10 -4 ~ 10 -1 S / cm are used as the antistatic agent, and the conductivity is measured by the four-probe method at 25℃±2℃ under a pressure of 10MPa, so that the antistatic agent itself has stable conductive capacity.

[0010] Preferably, the conductive reinforcing agent is one or more of carbon nanotubes and graphene nanosheets.

[0011] By adopting the technical scheme, the carbon nanotubes or graphene nanosheets are used as the conductive reinforcing agent, and these materials have a high aspect ratio or sheet structure, which can form a continuous conductive path in the nitrile rubber matrix.

[0012] Preferably, the carbon nanotubes and graphene nanosheets are both subjected to surface amination treatment, and the graphene nanosheet has 1-5 layers.

[0013] By adopting the technical scheme, the multi-walled carbon nanotubes and graphene nanosheets subjected to surface amination treatment are used, the surface amino groups can form covalent bonds or hydrogen bonds with the carboxyl groups of the graphene oxide, the interface bonding force between the conductive reinforcing agent and the antistatic agent is enhanced, and the dispersibility of the carbon nanotubes and graphene nanosheets in the nitrile rubber is improved; and since the graphene nanosheet has 1-5 layers, the few-layer structure has a high specific surface area and excellent electron transport capacity, and can form an efficient conductive path in the rubber matrix.

[0014] Preferably, the surface functional groups of the conductive reinforcing agent and the carboxyl groups of the graphene oxide can form hydrogen bonds or covalent bonds, and the conductive reinforcing agent and the acrylonitrile unit of the nitrile rubber are connected by hydrogen bonds to form a three-dimensional interpenetrating conductive network.

[0015] By adopting the above technical scheme, since the surface functional groups of the conductive reinforcing agent form hydrogen bonds or covalent bonds with the carboxyl groups of the graphene oxide, the interfacial bonding force between the conductive fillers is strengthened, and the phase separation phenomenon is reduced; and since the conductive reinforcing agent is connected with the acrylonitrile units of the nitrile rubber through hydrogen bonds, the compatibility of the fillers and the rubber matrix is improved, and the dispersion uniformity is improved.

[0016] Preferably, the preparation of the antistatic agent comprises the following steps:

[0017] S1, graphene oxide is pre-activated in a 1-3 mol / L HCl solution at 20-35℃ for 12h under magnetic stirring;

[0018] S2, ultrasonic dispersion is performed for 2h in water or an ethanol and water mixed system under a frequency of 40kHz, and the temperature of the ultrasonic dispersion process is less than 15℃;

[0019] S3, ammonium persulfate initiator is added in a molar ratio of 1:1.2, and polymerization reaction is performed at 5℃ for 8h;

[0020] S4, the obtained product is reduced by 10wt% ammonia water at pH 10 and a temperature of 60℃ for 2h.

[0021] By adopting the above technical scheme, since the graphene oxide is pre-activated in a 1-3 mol / L HCl solution at 20-35℃ for 12h, the hydrogen bonds on the surface of the graphene oxide are effectively destroyed, the functional groups such as carboxyl groups are fully exposed, and active sites are provided for subsequent reactions; since the graphene oxide and the aniline monomer are ultrasonically dispersed in water or an ethanol and water mixed system at a frequency of 40kHz and a temperature of less than 15℃ for 2h, the aniline monomer is uniformly adsorbed on the surface of the graphene oxide layer, and premature polymerization of the aniline due to excessively high temperature is avoided; since ammonium persulfate is added in a molar ratio of 1:1.2 to initiate polymerization reaction at 5℃ for 8h, and the obtained product is reduced by 10wt% ammonia water at pH 10 and a temperature of 60℃ for 2h, the polyaniline is in-situ polymerized on the surface of the graphene oxide to form a three-dimensional interpenetrating structure, and the reduction treatment improves the conductivity of the composite, therefore, the conductivity of the graphene oxide and polyaniline composite reaches 10 -4 ~10 -1 S / cm, and when the composite is compounded with nitrile rubber, a stable conductive network is formed, and the rubber is endowed with durable antistatic properties.

[0022] Preferably, the Mooney viscosity of the nitrile raw rubber is 70-80, and the acrylonitrile content is 26-40%.

[0023] By adopting the above technical scheme, since the nitrile butadiene raw rubber with a Mooney viscosity of 70-80 has suitable processing fluidity, is convenient to uniformly mix with various fillers, avoids difficulty in dispersion caused by excessively high viscosity or affects the strength of the rubber compound due to excessively low viscosity, and since the acrylonitrile content is controlled in the range of 26-40%, the content of the polar cyano group in the molecular chain of the nitrile butadiene rubber is moderate, which can not only enhance the interfacial compatibility of the rubber matrix and the carboxyl group of the graphene oxide through hydrogen bonding, but also ensure the elasticity and oil resistance of the rubber matrix.

[0024] Preferably, the active agent is composed of zinc oxide and stearic acid, the filling and reinforcing agent is one or more of diatomite, white carbon black and carbon black, the antioxidant is one or more of MB, 445 and RD, the softening agent is TP95 or RS107, the vulcanizing agent is one or more of sulfur, bis25 and DCP, and the accelerator is one or more of thiuram, thiazole or sulfenamide accelerators.

[0025] By adopting the above technical scheme, since the nitrile butadiene raw rubber with a Mooney viscosity of 70-80 has suitable processing fluidity, is convenient to uniformly mix with various fillers, avoids difficulty in dispersion caused by excessively high viscosity or affects the strength of the rubber compound due to excessively low viscosity, and since the acrylonitrile content is controlled in the range of 26-40%, the content of the polar cyano group in the molecular chain of the nitrile butadiene rubber is moderate, which can not only enhance the interfacial compatibility of the rubber matrix and the carboxyl group of the graphene oxide through hydrogen bonding, but also ensure the elasticity and oil resistance of the rubber matrix.

[0026] In a second aspect, the application provides a preparation method of the anti-static nitrile butadiene rubber, which comprises the following steps:

[0027] S1, compound pretreatment: pretreating the graphene oxide and polyaniline compound;

[0028] S2, main material mixing: putting the nitrile butadiene raw rubber, active agent, filling and reinforcing agent, antioxidant, softening agent, pretreated graphene oxide and polyaniline compound and conductive reinforcing agent into a banbury mixer and mixing for 15-20 minutes;

[0029] S3, plasticizing by discharging rubber: discharging rubber at 120-125℃ to obtain a mixture;

[0030] S4, vulcanizing system adding: adding a vulcanizing agent and an accelerator to the mixture;

[0031] S5, finishing: the mixture is transferred to an open mill at less than 80℃, and three triangular bag folding and two thin pass treatments are carried out, and the antistatic nitrile rubber is obtained by mixing.

[0032] By adopting the above technical scheme, since the step of pretreating the graphene oxide and polyaniline compound is adopted, impurities can be removed, the surface activity can be optimized, and the bonding force with the rubber matrix can be enhanced; since the nitrile raw rubber and each raw material are mixed in the internal mixer for 15-20 min, the strong shearing action of the internal mixer is used to realize the preliminary uniform dispersion of the conductive reinforcing agent and the compound; since the material is preliminarily fused by discharging the plastic at 120-125℃, the crosslinking reaction is controlled by adding the vulcanizing system, and the dispersion is further refined by three triangular bag foldings and two thin pass treatments in the open mill, the mechanical shearing force breaks the filler agglomeration, and a continuous conductive network is constructed, therefore, the effect that the filler is uniformly dispersed, the conductive network is stable, the antistatic performance is excellent, and the mechanical properties are good in the antistatic nitrile rubber is obtained.

[0033] Preferably, the pretreatment in S1 is that the graphene oxide and polyaniline compound are treated with silane coupling agent KH550 at 50-80℃ for 2-4h.

[0034] or ultrasonic dispersion in a mixed solvent of ethanol and water at a power of 300-500W for 30-60min.

[0035] By adopting the above technical scheme, since the graphene oxide and polyaniline compound are treated with silane coupling agent KH550 at 50-80℃ for 2-4h, the alkoxyl group of the silane coupling agent can form a covalent bond with the hydroxyl group on the surface of the compound after hydrolysis, and the other end organic functional group can react chemically or entangle physically with the nitrile rubber, thereby enhancing the interfacial compatibility of the compound and the rubber matrix. The cavitation effect generated by ultrasonic dispersion in a mixed solvent of ethanol and water at a power of 300-500W for 30-60min can effectively break the compound agglomerates, so that the compound is uniformly dispersed in the solvent and the specific surface area is increased.

[0036] In summary, the present application has the following beneficial effects:

[0037] 1、The present application adopts a specific weight part raw material composition including nitrile raw rubber, active agent, filling and reinforcing agent, antioxidant, softening agent, graphene oxide and polyaniline compound antistatic agent, vulcanizing agent, accelerator and conductive reinforcing agent, the conductive reinforcing agent is combined with the graphene oxide and polyaniline compound, and then a conductive network is constructed in the nitrile rubber matrix, thereby improving the problem that the traditional antistatic nitrile rubber mostly adopts a single conductive filler, the interfacial bonding force of the filler and the rubber matrix is weak, the conductive path is easy to break, and the antistatic performance is attenuated and the mechanical properties are damaged.

[0038] 2、The conductivity of the antistatic agent at 25°C±2°C under a pressure of 10 MPa is 10 -4 ~ 10 -1 S / cm, which ensures that the antistatic agent itself has good conductivity, and then forms a stable conductive path in the nitrile rubber system in cooperation with the conductive reinforcing agent, thereby improving the problem of static accumulation of rubber products caused by the insufficient conductivity of traditional antistatic agents, which cannot effectively remove the electric charge.

[0039] 3、The application uses surface aminated multi-walled carbon nanotubes and / or graphene nanosheets with 1-5 layers as conductive reinforcing agents, which enhances the hydrogen bonding between the aminated conductive reinforcing agents and the graphene oxide carboxyl groups and the acrylonitrile units of the nitrile rubber, and the high specific surface area of the few-layer graphene nanosheets improves the electron transport efficiency, thereby constructing a three-dimensional interpenetrating conductive network that is resistant to deformation, thereby improving the problem of the significant attenuation of antistatic performance with rubber deformation caused by the surface inertness and structural stacking of traditional conductive fillers, which leads to uneven dispersion in rubber and easy fracture of the conductive network. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 is a flowchart of the method provided by the application. DETAILED DESCRIPTION

[0041] The application will be further described in detail below in combination with the drawings and examples.

[0042] Technical concept: The technical concept of the application is derived from the targeted improvement of the technical defects of traditional antistatic nitrile rubber. In the prior art, traditional antistatic nitrile rubber often uses carbon black as an antistatic filler, but this scheme has three technical bottlenecks: first, the agglomeration of carbon black filler leads to uneven dispersion, resulting in fluctuations in antistatic performance; second, high filler content of carbon black is required to meet the conductive requirements, which in turn causes a significant decrease in the mechanical properties of rubber; and third, in dynamic use scenarios, the conductive network constructed by carbon black is prone to fracture during deformation due to the lack of strong interfacial interaction with the rubber matrix, resulting in the failure of antistatic performance.

[0043] To solve the above problems, the applicant has found through a large number of experimental researches that the complex of graphene oxide and polyaniline can produce a synergistic effect with nitrile rubber at a low filling amount. Specifically, the carboxyl groups of graphene oxide and the acrylonitrile units of nitrile rubber are enhanced by hydrogen bonding to improve the interfacial compatibility and avoid filler phase separation; the three-dimensional interpenetrating network formed by in-situ polymerization of polyaniline on the surface of graphene oxide layers reduces the percolation threshold of conductive flow by means of π-π conjugated structure; at the same time, the rigid layers of graphene oxide are combined with the elastic matrix of rubber, and the conductive path is protected by stress redistribution during dynamic deformation. Based on the above findings, the applicant further optimizes the raw material ratio and preparation process, and finally forms a technical solution for realizing long-lasting and stable antistatic performance by low filling amount of antistatic agent, effectively overcoming the inherent defects of traditional carbon black filling system.

[0044] The embodiment of the application provides an antistatic nitrile rubber, which comprises the following raw materials by weight: nitrile raw rubber 100 parts, active agent 1-7 parts, filling and reinforcing agent 15-50 parts, antioxidant 1-2 parts, softening agent 2-15 parts, antistatic agent 2-6 parts, vulcanizing agent 1.5-2.0 parts, accelerator 1-3 parts and conductive reinforcing agent 0.5-3 parts; the antistatic agent is a graphene oxide and polyaniline complex.

[0045] Specifically,

[0046] Through the combination of the above technical features, the conductive reinforcing agent and the graphene oxide and polyaniline complex synergistically construct a three-dimensional interpenetrating conductive network, the high aspect ratio or lamellar structure of the conductive reinforcing agent and the lamellar structure of the graphene oxide are interwoven, and a continuous conductive path is formed in the nitrile rubber matrix; the surface-aminated carbon nanotubes or few-layer graphene nanosheets enhance the interfacial bonding force between the conductive filler, the antistatic agent and the rubber matrix through the bonding of the surface functional groups with the carboxyl groups of graphene oxide and the hydrogen bonding with the acrylonitrile units of nitrile rubber, thereby improving the dispersion uniformity and enhancing the conductive performance of the rubber at a low filling amount, avoiding the mechanical performance degradation caused by traditional carbon black filling, and achieving the balance optimization of antistatic performance and physical performance; by using specific weight parts of raw materials including nitrile raw rubber, active agent, filling and reinforcing agent, antioxidant, softening agent, graphene oxide and polyaniline complex antistatic agent, vulcanizing agent, accelerator and conductive reinforcing agent, and the combination of the conductive reinforcing agent and the graphene oxide and polyaniline complex, a conductive network is further constructed in the nitrile rubber matrix, thereby solving the problem of traditional antistatic nitrile rubber which mostly uses a single conductive filler, resulting in weak interfacial bonding force between the filler and the rubber matrix and easy fracture of the conductive path, thereby causing the antistatic performance to decay and the mechanical performance to be damaged.

[0047] The conductivity of the antistatic agent at 25℃±2℃ and 10MPa pressure is 10 -4 ~10 -1 S / cm.

[0048] Specifically, by limiting the conductivity of the antistatic agent to 10 -4 ~ 10 -1 S / cm at 25°C ± 2°C under a pressure of 10 MPa, the antistatic agent itself can be ensured to have good conductivity. As the antistatic agent, the graphene oxide and polyaniline composite ensures that the conductivity parameter can effectively build a conductive network in the nitrile rubber system. At the same time, in combination with the synergistic effect of the conductive reinforcing agent and the antistatic agent, and the cooperation of each component in the nitrile rubber matrix, the antistatic agent is uniformly dispersed and stably present in the rubber, thereby imparting the antistatic nitrile rubber with sustained and stable antistatic properties, ensuring that the rubber product can effectively drain the charge and avoid static accumulation in actual application.

[0049] The conductive reinforcing agent is one or more of carbon nanotubes and graphene nanosheets.

[0050] Specifically, by using one or more of carbon nanotubes and graphene nanosheets as the conductive reinforcing agent, the high aspect ratio, high specific surface area, and excellent conductivity can be utilized to cooperatively build a continuous conductive path with the graphene oxide and polyaniline composite in the nitrile rubber matrix. The tubular structure of carbon nanotubes and the two-dimensional sheet structure of graphene nanosheets can interweave to form a three-dimensional conductive network; at the same time, the surface functional groups of the conductive reinforcing agent can form hydrogen bonds or covalent bonds with the carboxyl groups of graphene oxide, and the surface amino groups can be connected to the acrylonitrile units of nitrile rubber through hydrogen bonds, thereby enhancing the interfacial bonding force with the antistatic agent and the rubber matrix, improving the dispersion uniformity of the conductive filler in the rubber, and significantly improving the conductivity of the nitrile rubber at a low filler loading, avoiding the problem of mechanical property degradation caused by traditional filler filling, and achieving a balance and optimization of antistatic performance and physical properties.

[0051] Both the carbon nanotubes and the graphene nanosheets are subjected to surface amination treatment, and the number of layers of the graphene nanosheets is 1-5 layers.

[0052] Specifically, by using surface-aminated multi-walled carbon nanotubes and graphene nanosheets with 1-5 layers, the performance of the anti-static nitrile rubber can be effectively improved. The surface-aminated multi-walled carbon nanotubes have amino functional groups on the surface, which can form hydrogen bonds or covalent bonds with the carboxyl groups of graphene oxide, thereby enhancing the binding force with the antistatic agent; meanwhile, the amino groups can also be connected to the acrylonitrile units of the nitrile rubber through hydrogen bonds, thereby improving the dispersibility and compatibility of the carbon nanotubes in the rubber matrix. The few-layer graphene nanosheets with 1-5 layers have high specific surface area and excellent electron transport capacity, which can form efficient conductive pathways in the rubber and interweave with the carbon nanotubes to cooperatively build a three-dimensional conductive network. The combination of the two with the graphene oxide and polyaniline compound ensures uniform dispersion of the conductive fillers in the nitrile rubber and enhances the stability and deformation resistance of the conductive network, thereby significantly improving the durability of the antistatic performance while maintaining the mechanical properties of the rubber.

[0053] The surface functional groups of the conductive reinforcing agent can form hydrogen bonds or covalent bonds with the carboxyl groups of the graphene oxide, and the conductive reinforcing agent can be connected to the acrylonitrile units of the nitrile rubber through hydrogen bonds to form a three-dimensional interpenetrating conductive network.

[0054] Specifically, by forming hydrogen bonds or covalent bonds between the surface functional groups of the conductive reinforcing agent and the carboxyl groups of the graphene oxide, and connecting the conductive reinforcing agent to the acrylonitrile units of the nitrile rubber through hydrogen bonds to form a three-dimensional interpenetrating conductive network, the performance of the anti-static nitrile rubber can be significantly improved. The above bonding enhances the binding force between the conductive reinforcing agent and the graphene oxide and polyaniline compound, which is not easy to separate during the mixing process, ensuring uniform dispersion of the conductive fillers in the rubber matrix; at the same time, the hydrogen bonding between the conductive reinforcing agent and the nitrile rubber improves the compatibility of the fillers and the rubber, avoiding agglomeration. The formation of a three-dimensional interpenetrating conductive network enables efficient electron transport within the rubber, and even if the rubber deforms, the conductive network can maintain continuity through stress redistribution of the bonding, thereby imparting the nitrile rubber with durable and stable antistatic performance while ensuring good mechanical properties.

[0055] The preparation of the antistatic agent includes the following steps:

[0056] S1, magnetic stirring of graphene oxide in a 1-3 mol / L HCl solution at 20-35℃ for 12h pre-activation;

[0057] S2, ultrasonic dispersion of the graphene oxide and aniline monomers in water or an ethanol-water mixture at a mass ratio of 1:15 under ultrasonic dispersion at a frequency of 40 kHz for 2h, and the temperature during the ultrasonic dispersion process is less than 15℃;

[0058] S3, addition of ammonium persulfate initiator at a molar ratio of 1:1.2, and polymerization reaction at 5℃ for 8h;

[0059] S4, the obtained product is reduced by 10wt% ammonia water at pH 10 and 60℃ for 2h.

[0060] Specifically, by adopting the above anti-static agent preparation steps, the performance of the graphene oxide and polyaniline composite can be effectively improved. In the S1 step, the graphene oxide is pre-activated by magnetic stirring in a 1-3 mol / L HCl solution at 20-35℃ for 12h, which can destroy the surface hydrogen bond and fully expose the carboxyl and other functional groups, providing active sites for subsequent reactions; in the S2 step, the aniline monomer is uniformly adsorbed on the surface of the graphene oxide layer by ultrasonic dispersion in water or an ethanol-water mixture at a frequency of 40kHz and a temperature of less than 15℃ for 2h, avoiding premature polymerization of aniline due to excessive temperature; in the S3 step, 1:1.2 molar ratio of ammonium persulfate initiator is added for polymerization at 5℃ for 8h, promoting in-situ polymerization of polyaniline on the surface of graphene oxide to form a three-dimensional structure; in the S4 step, 10wt% ammonia water is used for reduction at pH 10 and 60℃ for 2h, which can improve the conductivity of the composite. The above steps cooperate with each other to prepare a graphene oxide and polyaniline composite with suitable electrical conductivity. When the composite is compounded with nitrile rubber, a stable conductive network can be formed, which gives the rubber excellent antistatic properties.

[0061] The Mooney viscosity of the nitrile raw rubber is 70-80, and the acrylonitrile content is 26-40%.

[0062] Specifically, by using nitrile raw rubber with a Mooney viscosity of 70-80 and an acrylonitrile content of 26-40%, the antistatic nitrile rubber can have good processing performance and comprehensive performance. Nitrile raw rubber with a Mooney viscosity of 70-80 has moderate fluidity, which can be uniformly dispersed by mechanical shear force when mixed with active agents, filling and reinforcing agents, antistatic agents and other raw materials during mixing and open milling, avoiding mixing difficulties due to high viscosity or insufficient strength of the rubber compound due to low viscosity. The acrylonitrile content of 26-40% allows the nitrile rubber molecular chain to contain an appropriate amount of polar cyano groups, which can form hydrogen bonds with the carboxyl groups of graphene oxide and the amino groups of conductive enhancers, enhancing the interfacial bonding between the rubber matrix and the antistatic agent and the conductive enhancer. On the other hand, this content range can ensure that the nitrile rubber maintains elasticity while having good oil resistance and chemical stability. The synergistic effect of the two makes the nitrile rubber have good conductive filler coating during mixing, and the conductive network is stable after shaping, ultimately giving the antistatic nitrile rubber excellent antistatic properties and mechanical properties.

[0063] The active agent is composed of zinc oxide and stearic acid, the filling and reinforcing agent is one or more of diatomite, white carbon black and carbon black, the antioxidant is one or more of MB, 445 and RD, the softening agent is TP95 or RS107, the vulcanizing agent is one or more of sulfur, bis25 and DCP, and the accelerator is one or more of thiuram, thiazole or sulfenamide accelerators.

[0064] Specifically, the active agent composed of zinc oxide and stearic acid, zinc oxide can activate the vulcanization system, and stearic acid can improve the wettability and dispersibility of rubber and fillers; diatomite, white carbon black or carbon black as filling and reinforcing agent, using porous structure or high specific surface area, enhancing the physical strength of the rubber, and carbon black can also assist the conduction; the antioxidants such as MB, 445 or RD can effectively inhibit the oxidative degradation of rubber and prolong the service life; the softening agent such as TP95 or RS107 can adjust the flowability of the rubber, facilitating the mixing process; the vulcanizing agent such as sulfur, bis25 or DCP cooperates with the accelerators such as thiuram, thiazole or sulfenamide to control the crosslinking reaction rate and crosslinking density of the rubber, ensuring the stable vulcanization process. The combined action of various raw materials makes the antistatic nitrile rubber have good processing performance, excellent mechanical properties and anti-aging properties, while ensuring the stability of the antistatic function.

[0065] Please refer to the attached Figure 1 A preparation method of antistatic nitrile rubber, comprising the following steps:

[0066] S1, compound pretreatment: pretreatment of graphene oxide and polyaniline compound;

[0067] S2, main material mixing: put the nitrile rubber, active agent, filling and reinforcing agent, antioxidant, softening agent, pretreated graphene oxide and polyaniline compound, and conductive reinforcing agent into the internal mixer and mix for 15-20 min;

[0068] S3, plasticizing: plasticizing the mixture at 120-125℃;

[0069] S4, vulcanization system addition: adding vulcanizing agent and accelerator to the mixture;

[0070] S5, final mixing and shaping: transferring the mixture to the open mill at less than 80℃, folding three times by triangle and processing twice by thin pass, mixing to obtain the antistatic nitrile rubber, and the roller gap of thin pass processing is 0.5-1mm.

[0071] Specifically, by adopting the above preparation method, it can be ensured that each component of the anti-static nitrile rubber is uniformly dispersed and forms a stable conductive network. In S1 step, the graphene oxide and polyaniline composite are pretreated to optimize the surface activity and enhance the bonding force with the rubber matrix; in S2 step, the materials are mixed in the internal mixer for 15-20 min, and the strong shear force is used to make the raw nitrile rubber and each raw material preliminarily uniformly dispersed, especially the conductive reinforcing agent and the composite begin to build a conductive path; in S3 step, the plasticizing is carried out at 120-125℃ to promote the fusion of the materials and form a preliminary network structure; in S4 step, the vulcanizing system is added to prepare for the subsequent cross-linking reaction; in S5 step, the three triangular bag folding and the two thin pass processing with a roll gap of 0.5-1mm are carried out through the open mill at less than 80℃, which further refines the dispersion, breaks the filler agglomeration through mechanical shear force, and perfects and stabilizes the conductive network. The method controls the mixing temperature, time and mechanical action step by step, so that the conductive filler is uniformly dispersed in the rubber matrix to form a continuous and stable three-dimensional conductive network, thereby giving the anti-static nitrile rubber excellent and durable antistatic performance, while ensuring good mechanical properties.

[0072] The pretreatment in S1 is that the graphene oxide and polyaniline composite are treated with silane coupling agent KH550 at 50-80℃ for 2-4h. Or ultrasonic dispersion in ethanol and water mixed solvent for 30-60min at 300-500W power.

[0073] Specifically, by adopting the pretreatment method of treating the graphene oxide and polyaniline composite with silane coupling agent KH550 at 50-80℃ for 2-4h, or ultrasonic dispersion in ethanol and water mixed solvent for 30-60min at 300-500W power, the compatibility and dispersibility of the composite and the nitrile rubber can be optimized. When treated with silane coupling agent, the alkoxyl group of KH550 hydrolyzes to form a covalent bond with the hydroxyl group on the surface of the composite, and the organic functional group reacts chemically or physically entangles with the nitrile rubber, thereby enhancing the interfacial bonding force between the composite and the rubber matrix; when ultrasonic dispersion, the cavitation effect in the ethanol and water mixed solvent breaks the agglomerates of the composite, so that it is uniformly dispersed and the specific surface area is increased. Both pretreatment methods can avoid agglomeration of the composite during mixing, ensure uniform distribution of the composite and the conductive reinforcing agent in the rubber matrix, thereby effectively building a continuous conductive network, improving the stability and durability of the antistatic performance of the anti-static nitrile rubber, and maintaining the mechanical properties of the rubber.

[0074] Example 1

[0075] Preparation method:

[0076] The raw nitrile rubber 100 parts by weight, zinc oxide 0.5 parts by weight, stearic acid 0.5 parts by weight, white carbon black 15 parts by weight, antioxidant 445 1 part by weight, softener TP95 2 parts by weight, graphene oxide and polyaniline composite 2 parts by weight are added to the internal mixer and mixed for 15 minutes.

[0077] After the glue was discharged at 120℃, it was transferred to the open mill, 1.5 parts by weight of sulfur and 1 part by weight of accelerator were added, and mixing was carried out at a roller temperature <80℃, and the mixing rubber was prepared by three times of triangular bag folding and twice of thin pass treatment.

[0078] The mixing rubber was vulcanized on a flat vulcanizing machine at 170℃ for 400 seconds to prepare the sample.

[0079] Example 2

[0080] Preparation method:

[0081] 100 parts by weight of nitrile raw rubber, 2 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 32.5 parts by weight of white carbon black, 1.5 parts by weight of antioxidant 445, 8.5 parts by weight of softener TP95, 4 parts by weight of graphene oxide and polyaniline complex were added to the internal mixer and mixed for 15 minutes.

[0082] After the glue was discharged at 120℃, it was transferred to the open mill, 1.75 parts by weight of sulfur and 2 parts by weight of accelerator were added, and mixing was carried out at a roller temperature <80℃, and the mixing rubber was prepared by three times of triangular bag folding and twice of thin pass treatment.

[0083] The vulcanization conditions and post-treatment were consistent with example 1.

[0084] Example 3

[0085] Preparation method:

[0086] 100 parts by weight of nitrile raw rubber, 3.5 parts by weight of zinc oxide, 3.5 parts by weight of stearic acid, 50 parts by weight of white carbon black, 2 parts by weight of antioxidant 445, 15 parts by weight of softener TP95, 6 parts by weight of graphene oxide and polyaniline complex were added to the internal mixer and mixed for 15 minutes.

[0087] After the glue was discharged at 120℃, it was transferred to the open mill, 2 parts by weight of sulfur and 3 parts by weight of accelerator were added, and mixing was carried out at a roller temperature <80℃, and the mixing rubber was prepared by three times of triangular bag folding and twice of thin pass treatment.

[0088] The vulcanization conditions and post-treatment were consistent with example 1.

[0089] Example 4

[0090] The difference from example 1 is that 0.5 parts by weight of surface aminated carbon nanotubes are added to the internal mixer during the mixing stage for 15 minutes, and then continue to mix for 5 minutes.

[0091] The vulcanization conditions were consistent with example 1.

[0092] Example 5

[0093] The difference from Example 2 is that 1.75 parts by weight of surface-aminoated carbon nanotubes are added to the raw materials in the internal mixer during the 15-minute mixing stage, and then mixing is continued for 5 minutes.

[0094] The vulcanization conditions are the same as in Example 2.

[0095] Example 6

[0096] The difference from Example 3 is that 2.9 parts by weight of surface-aminoated carbon nanotubes are added to the raw materials in the internal mixer during the 15-minute mixing stage, and then mixing is continued for 5 minutes.

[0097] The vulcanization conditions are the same as in Example 3.

[0098] Example 7

[0099] The difference from Example 1 is that 0.5 parts by weight of graphene nanosheets are added to the raw materials in the internal mixer during the 15-minute mixing stage, and then mixing is continued for 5 minutes.

[0100] The vulcanization conditions are the same as in Example 1.

[0101] Example 8

[0102] The difference from Example 2 is that 1.75 parts by weight of graphene nanosheets are added to the raw materials in the internal mixer during the 15-minute mixing stage, and then mixing is continued for 5 minutes.

[0103] The vulcanization conditions are the same as in Example 2.

[0104] Example 9

[0105] The difference from Example 3 is that 2.8 parts by weight of graphene nanosheets are added to the raw materials in the internal mixer during the 15-minute mixing stage, and then mixing is continued for 5 minutes.

[0106] The vulcanization conditions are the same as in Example 3.

[0107] Comparative Example 1

[0108] 100 parts by weight of acrylonitrile rubber (Zeon 1043), 2 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 32.5 parts by weight of white carbon black, 1.5 parts by weight of antioxidant 445, and 8.5 parts by weight of softener TP95 are added to an internal mixer and mixed for 15 minutes.

[0109] After discharging at 120°C, the mixture is transferred to an open mill, 1.5 parts by weight of sulfur and 1 part by weight of accelerator are added, and mixing is performed at a roll temperature <80°C. The mixed rubber is prepared by folding three times and thinning twice.

[0110] The mixed rubber is vulcanized on a flat vulcanizing machine at 170°C for 400 seconds to obtain a test sample.

[0111] Comparative Example 2

[0112] Preparation method:

[0113] The rest of the proportion is the same as Comparative Example 1, and the antistatic agent is carbon black N550, and the addition amount is 20 parts by weight.

[0114] After the glue is discharged at 120°C, it is transferred to an open mill, 1.75 parts by weight of sulfur and 2 parts by weight of accelerator are added, and mixing is carried out at a roll temperature <80°C. The mixing rubber is prepared by folding three times and thinning twice.

[0115] The curing conditions and post-treatment are consistent with Example 1.

[0116] Comparative Example 3

[0117] The rest of the proportion is the same as Comparative Example 1, and the antistatic agent is pure graphene oxide, and the addition amount is 4 parts by weight.

[0118] After the glue is discharged at 120°C, it is transferred to an open mill, 2 parts by weight of sulfur and 3 parts by weight of accelerator are added, and mixing is carried out at a roll temperature <80°C. The mixing rubber is prepared by folding three times and thinning twice.

[0119] The curing conditions and post-treatment are consistent with Example 1.

[0120] The nitrile rubber of the above comparative examples and examples uses RYON 1043, zinc oxide uses Taizhou Huaye Zinc Industry Co., Ltd., stearic acid uses Taiko Brownization 1801, white carbon black uses Nanji Chemical 255, antioxidant uses Saint-Luc 445, softener uses HALLSTAR TP95, sulfur uses EXXON S-80GN, accelerator uses EXXON CBS-80 and / or EXXON TT-80, when EXXON CBS-80 and EXXON TT-80 are used together, the amount of EXXON CBS-80 is 80% of the total weight of the accelerator, and carbon black uses Cabot carbon black N550.

[0121] Performance test

[0122] Test method and test method:

[0123] Volume resistance test: four-electrode method, test voltage 500V, read after 1 hour, according to GB / T1410-2006 standard.

[0124] Tensile strength test: according to GB / T528-2009 standard, dumbbell-shaped sample, tensile speed 500mm / min.

[0125] Dynamic resistance stability test:

[0126] Sample size: 100mm x 25mm x 2mm, installed on a dynamic bending tester;

[0127] Test conditions: bending amplitude ± 45°, frequency 1Hz, ambient temperature 23℃, humidity 50%RH, cycle 1 million times;

[0128] After every 10,000 cycles, the volume resistance was measured by four-electrode method, the resistance change rate (ΔR / R0) was calculated according to the formula ΔR / R0=(R-R0) / R0x100%, and the average value of 3 groups of samples was taken, and the standard was referred to ASTM D430.

[0129] Experimental data table:

[0130] Group Antistatic agent type Conductive enhancer type Volume resistance (Ω-cm) Tensile strength (MPa) Dynamic resistance stability (AR / R0) Comparative Example 1 No addition - 1.8 x 10 10 ]]> 12.3 - Comparative Example 2 Carbon black N550 (20 phr) - 5.3 x 10 8 ]] 14.5 55% Comparative Example 3 Pure graphene oxide (4 phr) - 3.1 x 10 7 ]] 13.0 32% Example 1 Graphene oxide and polyaniline composite (2 phr) - 8.3 x 10 6 ]]> 14.2 18% Example 2 Graphene oxide and polyaniline composite (4 phr) - 5.9 x 10 6 ]]> 15.5 12% Example 3 Graphene oxide and polyaniline composite (6 phr) - 2.0 x 10 6 ]]> 15.8 10% Example 4 Graphene oxide and polyaniline composite (2 phr) Surface-aminated multi-walled carbon nanotubes (0.5 phr) 3.5 x 10 6 ]]> 15.6 15% Example 5 Graphene oxide and polyaniline composite (4 phr) Surface-aminated multi-walled carbon nanotubes (1.75 phr) 8.1 x 10 5 ]]> 17.2 5% Example 6 Graphene oxide and polyaniline composite (6 phr) Surface-aminated multi-walled carbon nanotubes (2.9 phr) 5.6 x 10 5 ]]> 17.0 6% Example 7 Graphene oxide and polyaniline composite (2 phr) Surface-aminated graphene nanosheets (0.5 phr) 3.0 x 10 6 ]]> 15.3 16% Example 8 Graphene oxide and polyaniline composite (4 phr) Surface-aminated graphene nanosheets (1.75 phr) 7.7 x 10 5 ]]> 16.9 6% Example 9 Graphene oxide and polyaniline composite (6 phr) Surface-aminated graphene nanosheets (2.8 phr) 5.3 x 10 5 ]]> 16.7 7%

[0131] From the above experimental data table:

[0132] Combining Examples 1-9 and Comparative Examples 1-3 and combining the experimental data table, it can be seen that the volume resistance of Comparative Example 1 without adding an antistatic agent is as high as 1.8x10 10 Ω·cm, without antistatic effect; the volume resistance of Comparative Example 2 filled with traditional carbon black is 5.3x10 8 Ω·cm, has a certain antistatic ability but needs a high filling amount; the volume resistance of Comparative Example 3 filled with pure graphene oxide is 3.1x10 7 Ω·cm, the performance is better than carbon black but still limited. Examples 1-3 only use graphene oxide and polyaniline composite, although the addition amount of the remaining components is different, but the volume resistances are effectively reduced compared with Comparative Examples 1-3, among which the composite itself improves the antistatic performance by constructing a conductive network. Examples 4-9 with conductive enhancer, in the comparison of Examples 1-4-7, Examples 2-5-8 and Examples 3-7-9, the volume resistances are further reduced: such as Example 5 to 8.1x10 5 Ω·cm, Example 8 to 7.7x10 5 Ω·cm, which is significantly reduced compared with the corresponding Example 2 without enhancer. This shows that the combination of conductive enhancer and composite can construct a more dense conductive path through structural interweaving and synergy, solving the problem of uneven dispersion and low conductive efficiency of traditional single filler.

[0133] The tensile strength of Comparative Example 2 is 14.5 MPa, and that of Comparative Example 3 is 13.0 MPa; the tensile strength of Examples 1-3 increases from 14.2 MPa to 15.8 MPa, which is better than that of the traditional single filler. After adding the conductive reinforcing agent, the mechanical properties are further improved: the tensile strength of Example 5 reaches 17.2 MPa, and that of Example 8 reaches 16.9 MPa, which is about 11%-11.6% higher than that of Example 2 without the reinforcing agent. This is because the rigid layers of graphene oxide, the three-dimensional network of polyaniline, and the high aspect ratio structure of the conductive reinforcing agent are combined with the nitrile rubber matrix through hydrogen bonds, which not only avoids the strength decrease caused by traditional high filling, but also improves the overall mechanical properties of the rubber through interface bonding.

[0134] The dynamic resistance stability of Comparative Example 2 and Comparative Example 3 is not good, because the interface between the traditional filler and the rubber is weak, and the network is easy to break; compared with Comparative Example 2 and Comparative Example 3, the dynamic resistance change rate of Example 2 and Example 3 is effectively reduced, which shows that the interface hydrogen bonding between the composite and the rubber can enhance the network stability. After adding the conductive reinforcing agent, the dynamic stability is further optimized: the dynamic resistance change rate of Example 5 and Example 8 is reduced by about 50%-58% compared with Example 2. This is because the surface functional groups of the conductive reinforcing agent form hydrogen bonds or covalent bonds with the carboxyl groups of the composite, and also connect with the acrylonitrile units of the nitrile rubber through hydrogen bonds, so that the conductive network remains continuous through stress redistribution during dynamic deformation, which fundamentally improves the problem of anti-static performance decay caused by poor interface compatibility in the traditional single filler system.

[0135] By using nitrile rubber crumb, active agent and other raw materials, and the combination of graphene oxide and polyaniline composite and conductive reinforcing agent, a stable three-dimensional conductive network is constructed in the nitrile rubber matrix, and the comprehensive optimization of anti-static performance, mechanical properties and dynamic stability is realized, thereby improving the problem of anti-static performance decay and mechanical property damage caused by the use of single conductive filler in traditional anti-static nitrile rubber.

[0136] Finally, it should be pointed out that the above description is only a preferred embodiment of the present application and is not intended to limit the present application, although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacement of some technical features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An antistatic nitrile rubber, characterized by, The raw materials include the following weight parts: butyronitrile raw rubber 100 parts, active agent 1-7 parts, filling and reinforcing agent 15-50 parts, antioxidant 1-2 parts, softener 2-15 parts, antistatic agent 2-6 parts, vulcanizing agent 1.5-2.0 parts, accelerator 1-3 parts and conductive reinforcing agent 0.5-3 parts; the antistatic agent is a graphene oxide and polyaniline compound.

2. The anti-static nitrile rubber according to claim 1, wherein, The antistatic agent has an electrical conductivity of 10 -4 S / cm at 25°C ± 2°C under a pressure of 10 MPa. -1 S / cm at 25°C ± 2°C under a pressure of 10 MPa.

3. The anti-static nitrile rubber according to claim 1, wherein, The conductive reinforcing agent is one or more of carbon nanotubes and graphene nanosheets.

4. The anti-static nitrile rubber according to claim 3, wherein, The carbon nanotubes and graphene nanosheets are both subjected to surface amination treatment, and the graphene nanosheets have 1-5 layers.

5. The anti-static nitrile rubber according to claim 1, wherein, The surface functional groups of the conductive reinforcing agent can form hydrogen bonds or covalent bonds with the carboxyl groups of the graphene oxide, and the conductive reinforcing agent is connected to the acrylonitrile units of the butyronitrile rubber through hydrogen bonds to form a three-dimensional interpenetrating conductive network.

6. The anti-static nitrile rubber of claim 1, wherein, The preparation of the antistatic agent includes the following steps: S1, graphene oxide is pre-activated by magnetic stirring in a 1-3 mol / L HCl solution at 20-35℃ for 12h; S2, ultrasonic dispersion of the graphene oxide and aniline monomers at a mass ratio of 1:15 in water or an ethanol and water mixture at a frequency of 40 kHz for 2h, the temperature during the ultrasonic dispersion process being less than 15℃; S3, addition of ammonium persulfate initiator at a molar ratio of 1:1.2, polymerization reaction at 5℃ for 8h; S4, reduction treatment of the obtained product with 10wt% ammonia water at pH 10 and a temperature of 60℃ for 2h.

7. The anti-static nitrile rubber according to claim 1, wherein, The butyronitrile raw rubber has a Mooney viscosity of 70-80 and an acrylonitrile content of 26-40%.

8. The anti-static nitrile rubber of claim 1, wherein, The active agent is composed of zinc oxide and stearic acid, the filling and reinforcing agent is one or more of diatomite, white carbon black and carbon black, the antioxidant is one or more of MB, 445 and RD, the softener is TP95 or RS107, the vulcanizing agent is one or more of sulfur, bis 25 and DCP, and the accelerator is one or more of thiuram, thiazole or sulfenamide accelerators.

9. A method for preparing an antistatic nitrile rubber, applied to the antistatic nitrile rubber according to any one of claims 1 to 8, characterized in that, The method includes the following steps: S1, compound pretreatment: pretreatment of the graphene oxide and polyaniline compound; S2, main material mixing: butyronitrile raw rubber, active agent, filling and reinforcing agent, antioxidant, softener, the pretreated graphene oxide and polyaniline compound and conductive reinforcing agent are put into a banbury mixer and mixed for 15-20min; S3, plasticizing and discharging: plasticizing and discharging at 120-125℃ to obtain a mixture; S4, addition of a vulcanizing system: addition of a vulcanizing agent and an accelerator to the mixture; S5, final mixing and forming: the mixture is transferred to an open mill at less than 80℃, and three triangular bag folding and two thin pass treatments are performed, and the mixture is mixed to obtain the antistatic butyronitrile rubber, the roll gap of the thin pass treatment being 0.5-1mm.

10. The method of claim 9, wherein the nitrile rubber is prepared by adding the antioxidant to the nitrile rubber in the presence of the antistatic agent. In the pretreatment in S1, the graphene oxide and polyaniline compound are treated with silane coupling agent KH550 at 50-80℃ for 2-4h.

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