Antistatic silicone rubber composite and method for producing the same

Abstract

The application specifically relates to an antistatic silicone rubber composite material and a preparation method thereof. The silicone rubber composite material comprises the following raw materials in parts by weight: 90-110 parts of silicone rubber raw rubber, 15-30 parts of reinforcing filler, 12-20 parts of epoxy-quaternary ammonium salt bifunctional modified carbon nanotube, 3-8 parts of structure control agent and 0.5-2 parts of vulcanizing agent. The antistatic silicone rubber composite material is prepared by compounding the raw materials such as the silicone rubber raw rubber, the reinforcing filler, the epoxy-quaternary ammonium salt bifunctional modified carbon nanotube and the structure control agent. The composite material has both antistatic function and excellent mechanical properties, the surface resistivity change rate is small after high-temperature and high-humidity accelerated aging test, and the antistatic performance has excellent durability.

Description

Technical Field

[0001] This invention relates to the field of silicone rubber composite materials technology, specifically to an antistatic silicone rubber composite material and its preparation method. Background Technology

[0002] Silicone rubber is widely used in electronics, medical devices, aerospace, and other fields due to its excellent resistance to high and low temperatures, chemical stability, electrical insulation, and physiological inertness. However, silicone rubber has a high volume resistivity, making it an excellent electrical insulator, but it is also prone to static electricity accumulation during friction and peeling processes. Static electricity accumulation can not only attract dust and contaminate the surface of products, but in severe cases, it can also cause electrostatic discharge that breaks down sensitive electronic components, or even lead to safety accidents such as fires and explosions.

[0003] In existing technologies, conductive fillers are commonly added to silicone rubber. By adding conductive fillers such as conductive carbon black, carbon nanotubes, and graphene, conductive pathways are formed in the matrix to achieve electrostatic dissipation. Among these, carbon nanotubes have attracted widespread attention due to their excellent conductivity and mechanical properties. However, because carbon nanotubes have a large specific surface area and high surface energy, they lack affinity with the silicone rubber matrix and are prone to aggregation, resulting in an incomplete conductive network and unstable antistatic effect. High amounts of carbon nanotubes lead to a deep black color and significant issues with blackening / powdering in the finished product. Therefore, developing a silicone rubber composite material with good antistatic properties, good antistatic stability, and excellent mechanical properties is of great significance. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of the prior art by providing an antistatic silicone rubber composite material. This antistatic silicone rubber composite material exhibits excellent antistatic properties, good antistatic stability, and good mechanical properties. The preparation method of this antistatic silicone rubber composite material is stable, easy to control, and conducive to industrial production.

[0005] The objective of this invention is achieved through the following technical solution: an antistatic silicone rubber composite material, comprising the following raw materials in parts by weight: 90-110 parts of raw silicone rubber, 15-30 parts of reinforcing filler, 12-20 parts of epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes, 3-8 parts of structure control agent, and 0.5-2 parts of vulcanizing agent.

[0006] Furthermore, the raw silicone rubber is vinyl silicone rubber.

[0007] Furthermore, the reinforcing filler is silica.

[0008] Furthermore, the structure control agent is at least one of hydroxyl silicone oil, hexamethyldisilazane, and diphenylsilanediol.

[0009] Furthermore, the vulcanizing agent is at least one selected from 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, bis(2,4-dichlorobenzoyl)peroxide, di-tert-butylperoxide, and dicumyl peroxide.

[0010] Furthermore, the preparation method of the epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes includes the following steps: A1. Mix 1,2-dimethoxy-4-allylbenzene, hydrogen-containing silicone oil and dimethyl carbonate evenly, add catalyst and react to obtain product one; A2. Mix dimethyl diallyl ammonium chloride, glycidyl methacrylate, dimethyl carbonate and catalyst evenly to obtain product 2; add product 2 dropwise to product 1 to react; after the reaction is completed, remove the residual catalyst, filter and distill under reduced pressure to obtain epoxy-quaternary ammonium salt modified polysiloxane; disperse the epoxy-quaternary ammonium salt modified polysiloxane in a solvent to obtain epoxy-quaternary ammonium salt modified polysiloxane solution; A3. Carbon nanotubes are added to a mixed acid consisting of concentrated sulfuric acid and concentrated nitric acid for reaction. After cooling, the mixture is filtered, washed with water until neutral, and dried to obtain oxidized carbon nanotubes. The oxidized carbon nanotubes are dispersed in a solvent to obtain a carbon nanotube dispersion. A4. The carbon nanotube dispersion was added dropwise to the epoxy-quaternary ammonium salt modified polysiloxane solution for reaction. After cooling, the solution was filtered, washed and dried to obtain epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes.

[0011] This invention prepares polysiloxane-based epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes via a hydrosilylation reaction of 1,2-dimethoxy-4-allylbenzene with hydrogen-containing silicone oil. Covalent grafting is then achieved through ring-opening reactions between the epoxy groups and the carboxyl and hydroxyl groups on the carbon nanotube surface. Simultaneously, the polysiloxane backbone in the epoxy-quaternary ammonium salt bifunctional modified carbon nanotube molecule exhibits good compatibility with the silicone rubber matrix, effectively promoting uniform dispersion of carbon nanotubes within the matrix and avoiding the degradation of antistatic properties caused by migration and precipitation of traditional small molecules. The epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes simultaneously contain quaternary ammonium salt ionic groups and a polysiloxane backbone, which, after combining with the carbon nanotubes and dispersing within the silicone rubber matrix, ensure that the resulting composite material maintains stable antistatic properties under varying environmental humidity conditions and possesses excellent mechanical properties.

[0012] Further, in step A1, by weight, 1-4 parts of 1,2-dimethoxy-4-allylbenzene, 10-20 parts of hydrogen-containing silicone oil, and 5-20 parts of dimethyl carbonate are mixed, and a platinum catalyst is added. The mixture is reacted at 60-90°C for 2-4 hours to obtain product one. The amount of platinum catalyst added is (1-10) × 10⁻⁶ of the total mass of the reaction system. -6 .

[0013] Further, in step A2, 1-3 parts by weight of dimethyl diallyl ammonium chloride, 1-3 parts by weight of glycidyl methacrylate, 5-10 parts by weight of dimethyl carbonate, and platinum catalyst are mixed evenly to obtain product two; the amount of platinum catalyst added is (1-10) × 10 of the total mass of the reaction system. -6 Add product 2 dropwise to product 1, heat to 50-70℃ and stir for 2-4 h. After the reaction is complete, remove the residual catalyst, filter and distill under reduced pressure to obtain epoxy-quaternary ammonium salt modified polysiloxane. Disperse the epoxy-quaternary ammonium salt modified polysiloxane in anhydrous ethanol to obtain epoxy-quaternary ammonium salt modified polysiloxane solution.

[0014] Furthermore, after the reaction is complete, activated carbon is added to the reaction system to adsorb the residual catalyst, and the activated carbon is removed by filtration.

[0015] Furthermore, in step A3, the mixed acid is composed of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 2-4:1, with the concentrated sulfuric acid having a mass concentration of 90-98% and the concentrated nitric acid having a mass concentration of 60-68%.

[0016] Furthermore, in step A4, the mass ratio of the epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes in the epoxy-quaternary ammonium salt modified polysiloxane solution to the carbon nanotubes in the carbon nanotube solution is 2-4:1-2.

[0017] Another object of the present invention is to provide a method for preparing the antistatic silicone rubber composite material, comprising the following steps: (1) Put the raw silicone rubber into a kneader, then add reinforcing filler, epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes and structure control agent, mix evenly and heat treat to obtain the basic compound. (2) Place the basic compound rubber in a two-roll mill, add vulcanizing agent, mix evenly and then sheet to obtain the rubber material to be vulcanized; (3) Add the rubber material to be vulcanized into the mold, perform secondary vulcanization, and cool to room temperature to obtain antistatic silicone rubber composite material.

[0018] The beneficial effects of this invention are as follows: This invention prepares an antistatic silicone rubber composite material by compounding raw silicone rubber, reinforcing fillers, epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes, and structure control agents. This composite material possesses both antistatic properties and excellent mechanical properties. After high-temperature and high-humidity accelerated aging tests, it exhibits a small change in surface resistivity and excellent durability in antistatic performance. The preparation method of this antistatic silicone rubber composite material is stable, easy to control, and conducive to industrial production. Detailed Implementation

[0019] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments. The content mentioned in the embodiments is not intended to limit the present invention.

[0020] In some embodiments of the present invention, an antistatic silicone rubber composite material comprises the following raw materials in parts by weight: 90-100 parts of vinyl silicone rubber, 15-30 parts of reinforcing filler, 12-20 parts of epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes, 3-8 parts of structure control agent, and 0.5-2 parts of vulcanizing agent.

[0021] In some embodiments of the present invention, the reinforcing filler is silica, which is at least one of precipitated silica and fumed silica. The specific surface area of ​​the precipitated silica is 100-200 m². 2 / g, the specific surface area of ​​the fumed silica is 150-400 m² / g. 2 / g.

[0022] The epoxy-quaternary ammonium salt bifunctional modified carbon nanotube of the present invention is an organic-inorganic composite conductive filler, which is formed by grafting polysiloxane containing epoxy groups and quaternary ammonium salt ionic groups on the surface of carbon nanotubes through the reaction of epoxy groups with carboxyl groups on the surface of carbon nanotubes.

[0023] In some embodiments of the present invention, the structure control agent is at least one of hydroxyl silicone oil, hexamethyldisilazane, and diphenylsilanediol.

[0024] In some embodiments of the present invention, the vulcanizing agent is at least one selected from 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, bis(2,4-dichlorobenzoyl) peroxide, di-tert-butyl peroxide, and dicumyl peroxide.

[0025] In some embodiments of the present invention, the preparation method of the epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes includes the following steps: A1. By weight, mix 1-4 parts of 1,2-dimethoxy-4-allylbenzene, 10-20 parts of hydrogen-containing silicone oil, and 5-20 parts of dimethyl carbonate, wherein the molar amount of Si-H groups in the hydrogen-containing silicone oil is greater than the molar amount of allyl groups in 1,2-dimethoxy-4-allylbenzene; add a catalyst and react at 60-90℃ for 2-4 hours to obtain product one; the catalyst is a platinum catalyst, specifically Castrol platinum catalyst, and the amount added is (1-10) × 10 of the total mass of the reaction system. -6 ; A2. By weight, take 1-3 parts of dimethyl diallyl ammonium chloride, 1-3 parts of glycidyl methacrylate, 5-10 parts of dimethyl carbonate, and the catalyst, and mix them evenly to obtain product two. Add product two dropwise to product one, heat to 50-70℃ and stir for 2-4 hours. After the reaction, add activated carbon to the reaction system, stir at 35-45℃ for 1-3 hours to adsorb the residual catalyst, filter to remove the activated carbon, and remove dimethyl carbonate and unreacted monomers by vacuum distillation of the filtrate to obtain epoxy-quaternary ammonium salt modified polysiloxane with epoxy groups and quaternary ammonium salt ion groups in the side chain. Disperse the epoxy-quaternary ammonium salt modified polysiloxane in anhydrous ethanol to obtain an epoxy-quaternary ammonium salt modified polysiloxane solution. The concentration of the epoxy-quaternary ammonium salt modified polysiloxane solution is 10-15 wt%. The catalyst is a platinum catalyst, and the amount added is (1-10) × 10 of the total mass of the reaction system. -6 The platinum catalyst used is a Castrol platinum catalyst. A3. Carbon nanotubes are added to a mixed acid composed of concentrated sulfuric acid and concentrated nitric acid, and reacted at 60-100℃ for 2-6 hours. After cooling, the mixture is filtered, washed with deionized water until neutral, and dried to obtain oxidized modified carbon nanotubes. The oxidized modified carbon nanotubes are dispersed in anhydrous ethanol to obtain a carbon nanotube dispersion. The concentration of the carbon nanotube dispersion is 1-2 wt%. A4. Under stirring conditions at 50-70℃, the carbon nanotube dispersion from step A3 is slowly added dropwise to the epoxy-quaternary ammonium salt modified polysiloxane solution from step A2. After the addition is complete, the reaction continues for 12-24 hours. After cooling to room temperature, the carbon nanotubes are obtained by filtration, washing, and drying.

[0026] In some embodiments of the present invention, in step A3, the mass concentration of concentrated sulfuric acid is 90-98%, and the mass concentration of concentrated nitric acid is 60-68%.

[0027] In some embodiments of the present invention, in step A4, the mass ratio of the epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes in the epoxy-quaternary ammonium salt modified polysiloxane solution to the carbon nanotubes in the carbon nanotube solution is 2-4:1-2.

[0028] In some embodiments of the present invention, a method for preparing an antistatic silicone rubber composite material includes the following steps: (1) Put the raw silicone rubber into a kneader, then add reinforcing filler, epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes and structure control agent, mix evenly and heat-treat at 100-140℃ for 1-3h to obtain the basic compound. (2) Place the basic compound in a two-roll mill, add the vulcanizing agent, mix evenly and then sheet to obtain the rubber material to be vulcanized; (3) Add the rubber material to be vulcanized into the mold, perform a first-stage vulcanization at 120-170℃ for 10-30 min, and then perform a second-stage vulcanization at 160-200℃ for 2-4 h. Cool to room temperature to obtain antistatic silicone rubber composite material.

[0029] Example 1

[0030] This embodiment provides an antistatic silicone rubber composite material, comprising the following raw materials in parts by weight: 100 parts vinyl silicone rubber, 20 parts silica, 16 parts epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes, 5 parts hydroxyl silicone oil, and 1.2 parts 2,5-dimethyl-2,5-di-tert-butylperoxyhexane. The vinyl silicone rubber is methyl vinyl silicone rubber raw rubber, specifically Dongjue Organosilicon 110-2 methyl vinyl silicone rubber, with a vinyl content of 0.13-0.18%. The hydroxyl silicone oil is Dow Corning PMX-0156 silicone oil. The silica is composed of precipitated silica and fumed silica in a mass ratio of 3:2.

[0031] Furthermore, the preparation method of the epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes includes the following steps: A1. By weight, 2.5 parts of 1,2-dimethoxy-4-allylbenzene, 15 parts of hydrogen-containing silicone oil, and 20 parts of dimethyl carbonate were mixed evenly; castor platinum catalyst was added and the mixture was reacted at 80℃ for 3 hours to obtain product one; the amount of castor platinum catalyst added accounted for 5 × 10⁻⁶ of the total mass of the reaction system. -6 The hydrogen-containing silicone oil is an end-side hydrogen-containing polysiloxane, and the selected hydrogen-containing silicone oil is Tianjiang TJ-100. A2. By weight, 2 parts of dimethyl diallyl ammonium chloride, 2 parts of glycidyl methacrylate, 8 parts of dimethyl carbonate, and casterplatin catalyst were mixed evenly to obtain product two. Product two was added dropwise to product one, and the mixture was heated to 60°C and stirred for 3 hours to allow the dimethyl diallyl ammonium chloride and glycidyl methacrylate to undergo hydrosilylation with the residual Si-H bonds in product one. After the reaction was completed, activated carbon was added to the reaction system, and the mixture was stirred at 40°C for 2 hours to adsorb the residual catalyst. The activated carbon was removed by filtration, and the filtrate was distilled under reduced pressure to obtain an epoxy-quaternary ammonium salt modified polysiloxane solution. The epoxy-quaternary ammonium salt modified polysiloxane was dispersed in anhydrous ethanol to prepare a 12 wt% epoxy-quaternary ammonium salt modified polysiloxane solution. The amount of casterplatin catalyst added accounted for 3 × 10⁻⁶ of the total mass of the reaction system. -6 ; A3. Carbon nanotubes were added to a mixed acid consisting of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1, and reacted at 80°C for 4 hours. After cooling, the mixture was filtered, washed with deionized water until neutral, and dried to obtain oxidized modified carbon nanotubes. The oxidized modified carbon nanotubes were dispersed in anhydrous ethanol to prepare a carbon nanotube dispersion with a concentration of 1.5 wt%. The mass concentration of concentrated sulfuric acid was 98%, and the mass concentration of concentrated nitric acid was 68%. Multi-walled carbon nanotubes with a diameter of 10-100 nm were selected. A4. Under stirring conditions at 60℃, the carbon nanotube dispersion from step A3 is slowly added dropwise to the epoxy-quaternary ammonium salt modified polysiloxane solution from step A2. The mass ratio of epoxy-quaternary ammonium salt modified polysiloxane to carbon nanotubes is 3:1. After the addition is complete, the reaction continues for 20 hours. After cooling to room temperature, the solution is filtered, washed, and dried to obtain epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes.

[0032] In this embodiment, the preparation method of the antistatic silicone rubber composite material includes the following steps: (1) Put vinyl silicone rubber into a kneader, then add silica, epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes and hydroxyl silicone oil, mix evenly and heat-treat at 120°C for 2 hours to obtain the basic compound. (2) Place the basic compound in a two-roll mill, add 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, mix evenly and then sheet to obtain the rubber compound to be vulcanized; (3) Add the rubber material to be vulcanized into the mold, vulcanize at 150°C for 15 min, vulcanize at 180°C for 3 h, and cool to room temperature to obtain antistatic silicone rubber composite material.

[0033] Example 2

[0034] This embodiment provides an antistatic silicone rubber composite material, comprising the following raw materials in parts by weight: 100 parts vinyl silicone rubber, 22 parts silica, 14 parts epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes, 5 parts hydroxyl silicone oil, and 1 part 2,5-dimethyl-2,5-di-tert-butylperoxyhexane.

[0035] Furthermore, the preparation method of the epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes includes the following steps: A1. By weight, 2.0 parts of 1,2-dimethoxy-4-allylbenzene, 15 parts of hydrogen-containing silicone oil, and 15 parts of dimethyl carbonate were mixed evenly; casterplatin catalyst was added and the mixture was reacted at 80℃ for 3 hours to obtain product one; the amount of casterplatin catalyst added accounted for 5 × 10⁻⁶ of the total mass of the reaction system. -6 ; A2. By weight, 1.5 parts of dimethyl diallyl ammonium chloride, 2.5 parts of glycidyl methacrylate, 8 parts of dimethyl carbonate, and casterplatin catalyst were mixed evenly to obtain product two. Product two was added dropwise to product one, and the mixture was heated to 60°C and stirred for 3 hours. After the reaction was completed, activated carbon was added to the reaction system, and the mixture was stirred at 40°C for 2 hours to adsorb the residual catalyst. The activated carbon was removed by filtration, and the filtrate was distilled under reduced pressure to obtain an epoxy-quaternary ammonium salt modified polysiloxane solution. The epoxy-quaternary ammonium salt modified polysiloxane was dispersed in anhydrous ethanol to prepare a 10 wt% epoxy-quaternary ammonium salt modified polysiloxane solution. The amount of casterplatin catalyst added accounted for 3 × 10⁻⁶ of the total mass of the reaction system. -6 ; A3. Carbon nanotubes were added to a mixed acid consisting of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1 and reacted at 80°C for 4 hours. After cooling, the mixture was filtered, washed with deionized water until neutral, and dried to obtain oxidized modified carbon nanotubes. The oxidized modified carbon nanotubes were dispersed in anhydrous ethanol to prepare a carbon nanotube dispersion with a concentration of 1.0 wt%. A4. Under stirring conditions at 60℃, the carbon nanotube dispersion from step A3 is slowly added dropwise to the epoxy-quaternary ammonium salt modified polysiloxane solution from step A2. The mass ratio of epoxy-quaternary ammonium salt modified polysiloxane to carbon nanotubes is 3:1. After the addition is complete, the reaction continues for 20 hours. After cooling to room temperature, the solution is filtered, washed, and dried to obtain epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes.

[0036] The rest of this embodiment is the same as that in Embodiment 1.

[0037] Example 3

[0038] This embodiment provides an antistatic silicone rubber composite material, comprising the following raw materials in parts by weight: 100 parts vinyl silicone rubber, 17 parts silica, 19 parts epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes, 6 parts hydroxyl silicone oil, and 1.5 parts 2,5-dimethyl-2,5-di-tert-butylperoxyhexane.

[0039] The rest of this embodiment is the same as that in Embodiment 1.

[0040] Comparative Example 1 The difference between this comparative example and Example 1 is that the silicone rubber composite material provided in this comparative example comprises the following raw materials in parts by weight: 100 parts vinyl silicone rubber, 20 parts silica, 4 parts carbon nanotubes, 5 parts hydroxyl silicone oil, and 1.2 parts 2,5-dimethyl-2,5-di-tert-butylperoxyhexane. The carbon nanotubes are unmodified multi-walled carbon nanotubes. The rest of the contents of this comparative example are the same as in Example 1.

[0041] Comparative Example 2 The difference between this comparative example and Example 1 is that the silicone rubber composite material provided in this comparative example uses an equal amount of epoxy-grafted carbon nanotubes instead of epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes. The preparation method of the epoxy-grafted carbon nanotubes is as follows: 4 parts of carbon nanotubes are oxidized according to step A3 of Example 1, dispersed in anhydrous ethanol, and 12 parts of glycidyl methacrylate and 10 parts of dimethyl carbonate are added. The mixture is stirred and reacted at 60°C for 12 hours. After filtration, washing, and drying, epoxy-grafted carbon nanotubes are obtained. The rest of the contents of this comparative example are the same as those of Example 1.

[0042] Comparative Example 3 The difference between this comparative example and Example 1 is that the silicone rubber composite material provided in this comparative example uses an equal amount of quaternary ammonium salt-adsorbed carbon nanotubes instead of epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes. The preparation method for each part of the quaternary ammonium salt-adsorbed carbon nanotubes is as follows: 4 parts of carbon nanotubes are oxidized according to step A3, dispersed in anhydrous ethanol, and 12 parts of dimethyl diallyl ammonium chloride are added. The mixture is stirred at 60°C for 6 hours, allowing the dimethyl diallyl ammonium chloride to be loaded onto the surface of the carbon nanotubes through electrostatic adsorption. After filtration, washing, and drying, the quaternary ammonium salt-adsorbed carbon nanotubes are obtained. The rest of the contents of this comparative example are the same as in Example 1.

[0043] The antistatic silicone rubber composites prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests. The sample thickness was 2 mm. The test results are shown in Table 1 below:

[0044] The performance testing methods are as follows: Surface resistivity was determined using the three-electrode method according to GB / T 1410-2006, with a sample thickness of 2 mm and a measuring electrode diameter of 50 mm. The test conditions for the resistance change rate after aging treatment were: 85℃ / 85% RH / 500h. Tensile strength was determined according to GB / T 528-2009, using a dumbbell-shaped I-type sample with a thickness of 2 mm and a tensile rate of 500 mm / min. Tear strength was determined according to GB / T 529-2008, using a right-angled sample without cuts, a thickness of 2 mm, and a tensile rate of 500 mm / min. For the blackening test, a 500g weight was pressed onto white paper and rubbed back and forth on the white paper 30 times with a stroke of approximately 60 mm, followed by visual evaluation.

[0045] This invention prepares an antistatic silicone rubber composite material by compounding raw silicone rubber, reinforcing filler, epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes, and structure control agent. The composite material has both antistatic function and excellent mechanical properties. After high temperature and high humidity accelerated aging test, the surface resistivity change rate is small and the product does not turn black.

[0046] The specific embodiments described above are further illustrations of the technical solution and beneficial effects of the present invention, and are not intended to limit the implementation methods. For those skilled in the art, any obvious substitutions without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. An antistatic silicone rubber composite material, characterized in that: The raw materials include the following parts by weight: 90-110 parts of silicone rubber raw rubber, 15-30 parts of reinforcing filler, 12-20 parts of epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes, 3-8 parts of structure control agent, and 0.5-2 parts of vulcanizing agent.

2. The antistatic silicone rubber composite material according to claim 1, characterized in that: The raw silicone rubber is vinyl silicone rubber.

3. The antistatic silicone rubber composite material according to claim 1, characterized in that: The reinforcing filler is silica.

4. The antistatic silicone rubber composite material according to claim 1, characterized in that: The structure control agent is at least one of hydroxyl silicone oil, hexamethyldisilazane, and diphenylsilanediol.

5. The antistatic silicone rubber composite material according to claim 1, characterized in that: The vulcanizing agent is at least one selected from 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, bis(2,4-dichlorobenzoyl)peroxide, di-tert-butylperoxide, and dicumyl peroxide.

6. The antistatic silicone rubber composite material according to claim 1, characterized in that: The preparation method of the epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes includes the following steps: A1. Mix 1,2-dimethoxy-4-allylbenzene, hydrogen-containing silicone oil and dimethyl carbonate evenly, add catalyst and react to obtain product one; A2. Mix dimethyl diallyl ammonium chloride, glycidyl methacrylate, dimethyl carbonate and catalyst evenly to obtain product 2; add product 2 dropwise to product 1 to react; after the reaction is completed, remove the residual catalyst, filter and distill under reduced pressure to obtain epoxy-quaternary ammonium salt modified polysiloxane. Epoxy-quaternary ammonium salt modified polysiloxane is dispersed in a solvent to obtain an epoxy-quaternary ammonium salt modified polysiloxane solution; A3. Carbon nanotubes are added to a mixed acid consisting of concentrated sulfuric acid and concentrated nitric acid for reaction. After cooling, the mixture is filtered, washed with water until neutral, and dried to obtain oxidized carbon nanotubes. The oxidized carbon nanotubes are dispersed in a solvent to obtain a carbon nanotube dispersion. A4. The carbon nanotube dispersion was added dropwise to the epoxy-quaternary ammonium salt modified polysiloxane solution for reaction. After cooling, the solution was filtered, washed and dried to obtain epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes.

7. The antistatic silicone rubber composite material according to claim 6, characterized in that: By weight, 1-4 parts of 1,2-dimethoxy-4-allylbenzene, 10-20 parts of hydrogen-containing silicone oil and 5-20 parts of dimethyl carbonate are mixed, a platinum catalyst is added, and the mixture is reacted at 60-90℃ for 2-4 hours to obtain product one.

8. The antistatic silicone rubber composite material according to claim 6, characterized in that: In step A3, the mixed acid is composed of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 2-4:1, with the concentrated sulfuric acid having a mass concentration of 90-98% and the concentrated nitric acid having a mass concentration of 60-68%.

9. The antistatic silicone rubber composite material according to claim 6, characterized in that: In step A4, the mass ratio of epoxy-quaternary ammonium salt modified polysiloxane in the epoxy-quaternary ammonium salt modified polysiloxane solution to carbon nanotubes in the carbon nanotube solution is 2-4:1-2.

10. A method for preparing an antistatic silicone rubber composite material as described in any one of claims 1-9, characterized in that: Includes the following steps: (1) Put the raw silicone rubber into a kneader, then add reinforcing filler, epoxy-quaternary ammonium salt bifunctional modified carbon nanotubes and structure control agent, mix evenly and heat treat to obtain the basic compound. (2) Place the basic compound rubber in a two-roll mill, add vulcanizing agent, mix evenly and then sheet to obtain the rubber material to be vulcanized; (3) Add the rubber material to be vulcanized into the mold, perform secondary vulcanization, and cool to room temperature to obtain antistatic silicone rubber composite material.

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