Rubber reinforcing agent, preparation method thereof and rubber composite material

Abstract

The invention provides a rubber reinforcing agent, a preparation method thereof and a rubber composite material, and belongs to the technical field of rubber reinforcement. The two-dimensional nano material has high specific surface area and strong interface action, so that the mechanical property of the rubber composite material is remarkably enhanced; the characteristics of high strength and high modulus of the spiral nano carbon fiber are utilized, the mechanical property of the rubber composite material can be enhanced, the spiral nano carbon fiber has a unique spiral structure, can be entangled with a rubber molecular chain to generate physical crosslinking, and is not easy to fall off under the action of external force, so that the mechanical property of the rubber composite material is improved. Therefore, it is ensured that the rubber reinforcing agent contains trace two-dimensional nano-materials and spiral nano-carbon fibers, and the mechanical property of the rubber composite material can be improved. The two-dimensional nanometer material and the spiral nanometer carbon fiber are coated with the rubber, the dispersity of the two-dimensional nanometer material and the spiral nanometer carbon fiber can be improved, and therefore it is further guaranteed that the mechanical property of the rubber composite material can be improved by adding a trace amount of the two-dimensional nanometer material and the spiral nanometer carbon fiber.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rubber reinforcing, in particular to a rubber reinforcing agent, a preparation method thereof and a rubber composite material. BACKGROUND

[0002] The rubber reinforcing agent is a compounding agent capable of improving the strength of rubber products, and improves the mechanical properties of rubber materials through physical or chemical action. It is a key additive in rubber processing, and its main functions include enhancing the wear resistance, hardness, tensile strength and strain modulus of rubber.

[0003] In the prior art, graphene and carbon nanotube composite materials are often used as rubber reinforcing agents. The carbon nanotubes are used to improve the hardness, tensile strength, strain modulus and wear resistance of rubber, and the graphene is used to improve the tear strength of rubber, so as to obtain a rubber composite material with good mechanical properties. However, since the carbon nanotubes have a very high axial elastic modulus, the interface bonding with rubber is weak, and they are easy to fall off in the rubber matrix, so that the reinforcing effect of the carbon nanotubes on rubber is limited. Therefore, in order to improve the mechanical properties of the rubber composite material, the addition amount of the carbon nanotubes and the graphene needs to be increased, which is generally up to 3.2%. However, the graphene and the carbon nanotubes are expensive, and the excessive addition will greatly increase the cost of the rubber composite material, which is not conducive to the industrialized production of the rubber composite material. SUMMARY

[0004] The present application provides a rubber reinforcing agent, a preparation method thereof and a rubber composite material. The rubber reinforcing agent provided by the present application has good reinforcing effect on rubber. The rubber composite material prepared by using the rubber reinforcing agent provided by the present application contains trace amounts of two-dimensional nanomaterials and spiral nanocarbon fibers, has good mechanical properties, low cost and can realize industrialized production.

[0005] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions: A rubber reinforcing agent, comprising rubber-coated two-dimensional nanomaterials and rubber-coated spiral nanocarbon fibers; the two-dimensional nanomaterials in the rubber-coated two-dimensional nanomaterials are graphene or boron nitride nanosheets.

[0006] Preferably, the mass ratio of the two-dimensional nanomaterials in the rubber-coated two-dimensional nanomaterials to the spiral nanocarbon fibers in the rubber-coated spiral nanocarbon fibers is (0.5-2):1.

[0007] Preferably, the rubber in the rubber-coated two-dimensional nanomaterials and the rubber-coated spiral nanocarbon fibers is independently selected from natural rubber, styrene-butadiene rubber, butadiene rubber, nitrile rubber, chlorobutyl rubber, ethylene-propylene rubber, butyl rubber and silicone rubber.

[0008] Preferably, the mass ratio of the two-dimensional nanomaterials to the rubber in the rubber-coated two-dimensional nanomaterials and the mass ratio of the helical nanocarbon fibers to the rubber in the rubber-coated helical nanocarbon fibers are independently (1-8):1.

[0009] The application also provides a preparation method of the rubber reinforcing agent. The mixed dispersion liquid of the two-dimensional nanomaterials and the helical nanocarbon fibers is mixed with the latex, and then demulsification is performed to obtain the rubber reinforcing agent. or comprises: the dispersion liquid of the two-dimensional nanomaterials and the dispersion liquid of the helical nanocarbon fibers are mixed with the latex respectively, and then demulsification is performed to obtain the rubber-coated two-dimensional nanomaterials and the rubber-coated helical nanocarbon fibers. The rubber-coated two-dimensional nanomaterials and the rubber-coated helical nanocarbon fibers are mixed to obtain the rubber reinforcing agent.

[0010] Preferably, the mass ratio of the two-dimensional nanomaterials to the latex and the mass ratio of the helical nanocarbon fibers to the latex are independently 1:(0.25-16).

[0011] Preferably, the solid content of the rubber in the latex is 12.5-80%.

[0012] Preferably, the demulsification is: the pH of the mixed liquid obtained by mixing is adjusted to 4-5, and then a calcium chloride aqueous solution is added for demulsification.

[0013] Preferably, after the demulsification is completed, the product after demulsification is sequentially subjected to solid-liquid separation and drying.

[0014] The application also provides a rubber composite material, which comprises, by weight fraction: 96-100 parts of rubber, 1-3 parts of sulfur, 2-7 parts of zinc oxide, 0.3-3 parts of stearic acid, 40-80 parts of white carbon black, 1.5-3 parts of polyethylene glycol 4000, 0.5-2.5 parts of accelerator DM, 0.5-1.5 parts of accelerator M, 0.2-1 part of accelerator DPG, and 0.5-4 parts of rubber reinforcing agent; the rubber reinforcing agent is the rubber reinforcing agent in the above technical solution or the rubber reinforcing agent prepared by the preparation method in the above technical solution.

[0015] The application provides a rubber reinforcing agent, which comprises rubber-coated two-dimensional nanomaterials and rubber-coated helical nanocarbon fibers; the two-dimensional nanomaterials in the rubber-coated two-dimensional nanomaterials are graphene or boron nitride nanosheets. The two-dimensional nanomaterials have high specific surface area and strong interface effect, which can significantly enhance the mechanical properties of the rubber composite; the helical nanocarbon fibers have high strength and high modulus, which can enhance the mechanical properties of the rubber composite; the helical nanocarbon fibers have a unique helical structure and can be entangled with rubber molecular chains to produce physical crosslinking, which is not easy to fall off when subjected to external force, so that the mechanical properties of the rubber composite can be improved by adding a small amount of two-dimensional nanomaterials and helical nanocarbon fibers in the rubber reinforcing agent; the two-dimensional nanomaterials and the helical nanocarbon fibers are coated with rubber, which can improve the dispersibility of the two-dimensional nanomaterials and the helical nanocarbon fibers, thereby improving the reinforcing effect of the two-dimensional nanomaterials and the helical nanocarbon fibers. The results of the examples show that when the content of graphene and helical nanocarbon fibers in the rubber reinforcing agent provided by the application is 0.8% of the rubber composite, the rubber composite prepared has a 300% modulus of 8.66 MPa, a tensile strength at break of 23.87 MPa, a tear strength of 55.74 KN / m, and an abrasion volume of 166.41 mm 3 . BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 Figure 1 is a TEM image of graphene in Example 1 of the application; Figure 2 Figure 2 is a TEM image of helical nanocarbon fibers in Example 1 of the application; Figure 3 Figure 3 is a TEM image of a rubber composite in Example 2 of the application. DETAILED DESCRIPTION

[0017] The application provides a rubber reinforcing agent, which comprises rubber-coated two-dimensional nanomaterials and rubber-coated helical nanocarbon fibers.

[0018] The rubber reinforcing agent provided by the application comprises rubber-coated two-dimensional nanomaterials. In the application, the two-dimensional nanomaterials have high specific surface area and strong interface effect, which can significantly enhance the mechanical properties of the rubber composite; the surface of the two-dimensional nanomaterials is coated with rubber, which can improve the dispersibility of the two-dimensional nanomaterials and more fully play the role of the two-dimensional nanomaterials in enhancing the mechanical properties of the rubber.

[0019] In the application, the two-dimensional nanomaterials in the rubber-coated two-dimensional nanomaterials can be graphene or boron nitride nanosheets. The application further improves the mechanical properties of the rubber composite by limiting the types of two-dimensional nanomaterials.

[0020] As an embodiment of the present application, the diameter of the two-dimensional nanometer material in the rubber-coated two-dimensional nanometer material can be 10-2000nm, 50-1000nm, or 100-800nm. By limiting the diameter of the two-dimensional nanometer material, the present application can reduce the agglomeration of the two-dimensional nanometer material and improve the reinforcing effect of the two-dimensional nanometer material on rubber.

[0021] As an embodiment of the present application, when the two-dimensional nanometer material in the rubber-coated two-dimensional nanometer material is graphene, the number of layers of the graphene can be 1-10 layers, 2-8 layers, or 3-5 layers.

[0022] As an embodiment of the present application, the rubber in the rubber-coated two-dimensional nanometer material can be natural rubber, styrene-butadiene rubber, cis-butadiene rubber, nitrile rubber, chlorobutyl rubber, ethylene-propylene rubber, butyl rubber, and silicone rubber. By limiting the type of rubber, the present application can ensure that the rubber reinforcing agent prepared can be applied to reinforcing the rubber used for preparing tires.

[0023] As an embodiment of the present application, the mass ratio of the two-dimensional nanometer material to rubber in the rubber-coated two-dimensional nanometer material can be (1-8):1. In the embodiments of the present application, the mass ratio of the two-dimensional nanometer material to rubber in the rubber-coated two-dimensional nanometer material can be specifically 1:1, 3:1, 5:1, 7:1, or 8:1. By limiting the mass ratio of the two-dimensional nanometer material to rubber in the rubber-coated two-dimensional nanometer material, the present application can ensure that the two-dimensional nanometer material has better dispersibility when it is subsequently used to prepare rubber composites, and thus is more conducive to exerting the reinforcing effect on rubber.

[0024] The rubber reinforcing agent provided by the present application also includes rubber-coated helical nanometer carbon fibers.

[0025] As an embodiment of the present application, the diameter of the helical nanometer carbon fiber in the rubber-coated helical nanometer carbon fiber can be 40-200nm, 80-150nm, or 100-130nm. As an embodiment of the present application, the structure of the helical nanometer carbon fiber in the rubber-coated helical nanometer carbon fiber can be braided, twisted, Y-shaped, worm-shaped, mixed-pitch-shaped, or lambda-shaped. By limiting the diameter and structure of the helical nanometer carbon fiber, the present application can improve the reinforcing effect of the helical nanometer carbon fiber on rubber.

[0026] As an embodiment of the present application, the rubber in the rubber-coated helical nanometer carbon fiber can be natural rubber, styrene-butadiene rubber, cis-butadiene rubber, nitrile rubber, chlorobutyl rubber, ethylene-propylene rubber, butyl rubber, and silicone rubber. By limiting the type of rubber, the present application can ensure that the rubber reinforcing agent prepared can be applied to reinforcing the rubber used for preparing tires.

[0027] As an embodiment of the present application, the mass ratio of the two-dimensional nanomaterials to the rubber in the rubber-coated spiral nanocarbon fibers is the same as the mass ratio of the spiral nanocarbon fibers to the rubber in the rubber-coated spiral nanocarbon fibers, which will not be described here.

[0028] As an embodiment of the present application, the mass ratio of the two-dimensional nanomaterials to the spiral nanocarbon fibers in the rubber-coated spiral nanocarbon fibers can be (0.5-2):1. In the embodiments of the present application, the mass ratio of the two-dimensional nanomaterials to the spiral nanocarbon fibers in the rubber-coated spiral nanocarbon fibers can be specifically 0.5:1, 1:1 or 2:1. The present application limits the mass ratio of the two-dimensional nanomaterials to the spiral nanocarbon fibers in the rubber-coated spiral nanocarbon fibers to ensure that the respective functions can be fully played, and at the same time, the rubber composite material with high tensile strength at break and high tear strength is obtained.

[0029] As an embodiment of the present application, the coating rate of the rubber-coated two-dimensional nanomaterials and the rubber-coated spiral nanocarbon fibers can be independently 50-100%, and can also be 80-90%. The present application further ensures the good dispersibility of the two-dimensional nanomaterials in the rubber-coated spiral nanocarbon fibers and the spiral nanocarbon fibers in the rubber-coated spiral nanocarbon fibers by limiting the coating rate.

[0030] The present application significantly enhances the mechanical properties of the rubber composite material by using the high specific surface area and strong interface effect of the two-dimensional nanomaterials; enhances the mechanical properties of the rubber composite material by using the high strength and high modulus characteristics of the spiral nanocarbon fibers, and ensures that the rubber reinforcing agent containing trace amounts of two-dimensional nanomaterials and spiral nanocarbon fibers can improve the mechanical properties of the rubber composite material by using the unique spiral structure of the spiral nanocarbon fibers to entangle with the rubber molecular chains to produce physical crosslinking, which is not easy to fall off when subjected to external force; improves the dispersibility of the two-dimensional nanomaterials and the spiral nanocarbon fibers by coating the two-dimensional nanomaterials and the spiral nanocarbon fibers with rubber, thereby further ensuring that the trace amounts of two-dimensional nanomaterials and spiral nanocarbon fibers can improve the mechanical properties of the rubber composite material.

[0031] The present application also provides a preparation method of the rubber reinforcing agent described in the above technical solution, which comprises: The mixed dispersion liquid of the two-dimensional nanomaterials and the spiral nanocarbon fibers is mixed with the latex, and then demulsification is performed to obtain the rubber reinforcing agent.

[0032] As an embodiment of the present application, the preparation of the mixed dispersion of the two-dimensional nanomaterial and the helical nanocarbon fiber can be mixing the two-dimensional nanomaterial and the helical nanocarbon fiber with water to obtain the mixed dispersion of the two-dimensional nanomaterial and the helical nanocarbon fiber. As an embodiment of the present application, the mass ratio of the sum of the mass of the two-dimensional nanomaterial and the helical nanocarbon fiber to the mass of water can be 1: (50-3200). In the embodiments of the present application, the mass ratio of the sum of the mass of the two-dimensional nanomaterial and the helical nanocarbon fiber to the mass of water can be specifically 1:50, 1:100, 1:200, 1:300, 1:400, 1:600, 1:800, 1:1200, 1:1600, 1:2000, 1:2400, 1:2800, or 1:3200. The present application limits the mass ratio of the sum of the mass of the two-dimensional nanomaterial and the helical nanocarbon fiber to the mass of water to ensure that the two-dimensional nanomaterial and the helical nanocarbon fiber are fully dispersed. As an embodiment of the present application, the mixing of the two-dimensional nanomaterial and the helical nanocarbon fiber with water can be carried out under ultrasonic conditions. As an embodiment of the present application, the time of ultrasonic can be 1-24 h. In the embodiments of the present application, the time of ultrasonic can be specifically 1 h, 2 h, 4 h, 8 h, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h, or 24 h.

[0033] As an embodiment of the present application, the latex can be one or more of natural rubber latex, styrene-butadiene rubber latex, cis-butadiene rubber latex, nitrile rubber latex, chloroprene rubber latex, ethylene-propylene rubber latex, butyl rubber latex, and silicone rubber latex. As an embodiment of the present application, the solid content of the rubber in the latex can be 12.5-80%, or 20-60%, or 30-50%. The present application limits the solid content of the rubber in the latex to ensure that the two-dimensional nanomaterial and the helical nanocarbon fiber can be completely coated. The present application does not have special limitations on the preparation method of the latex, and the latex required can be obtained by using the preparation method well known in the art.

[0034] As an embodiment of the present application, the mass ratio of the two-dimensional nanomaterial to the latex and the mass ratio of the helical nanocarbon fiber to the latex in the mixed dispersion of the two-dimensional nanomaterial and the helical nanocarbon fiber can independently be 1:(0.25-16). In the embodiments of the present application, the mass ratio of the two-dimensional nanomaterial to the latex and the mass ratio of the helical nanocarbon fiber to the latex in the mixed dispersion of the two-dimensional nanomaterial and the helical nanocarbon fiber can specifically be 1:0.25, 1:0.5, 1:2, 1:5, 1:10 or 1:16. By limiting the mass ratio of the two-dimensional nanomaterial to the latex and the mass ratio of the helical nanocarbon fiber to the latex in the mixed dispersion of the two-dimensional nanomaterial and the helical nanocarbon fiber, the present application further ensures that the rubber in the latex can sufficiently coat the two-dimensional nanomaterial and the helical nanocarbon fiber.

[0035] As an embodiment of the present application, the mixing of the mixed dispersion of the two-dimensional nanomaterial and the helical nanocarbon fiber with the latex can be carried out under stirring. As an embodiment of the present application, the stirring rate can be 150-800 r / min, and the stirring time can be 20-120 min. In the embodiments of the present application, the stirring rate can specifically be 150 r / min, 200 r / min, 250 r / min, 300 r / min, 350 r / min, 400 r / min, 450 r / min, 500 r / min, 600 r / min, 700 r / min or 800 r / min. In the embodiments of the present application, the stirring time can specifically be 20 min, 40 min, 60 min, 80 min, 100 min or 120 min.

[0036] As an embodiment of the present application, the demulsification can be adjusting the pH value of the mixed solution obtained by the mixing to 4-5, and then adding a calcium chloride aqueous solution.

[0037] As an embodiment of the present application, glacial acetic acid can be used to adjust the pH. As an embodiment of the present application, the pH adjustment is carried out under stirring. In the present application, the pH is adjusted to 4-5 to destroy the protective film on the surface of the latex, neutralize the negative charge on the surface of the emulsion, eliminate the electrostatic repulsion that maintains the stability of the emulsion, and thus help achieve the flocculation of the emulsion. As an embodiment of the present application, the mass fraction of calcium chloride in the aqueous calcium chloride solution can be 5-15%. In the embodiments of the present application, the mass fraction of calcium chloride in the aqueous calcium chloride solution can be specifically 5%, 10%, or 15%. In the present application, the calcium ions in the aqueous calcium chloride solution undergo strong hydration with water molecules, compete for free water molecules in the latex, destroy the hydration layer on the surface of the latex, and cause the latex to dehydrate and coagulate. As an embodiment of the present application, the aqueous calcium chloride solution is added dropwise. As an embodiment of the present application, the rate of dropwise addition can be 30-100 mL / min. In the embodiments of the present application, the rate of dropwise addition can be specifically 30 mL / min, 40 mL / min, 50 mL / min, 60 mL / min, 70 mL / min, 80 mL / min, 90 mL / min, or 100 mL / min. As an embodiment of the present application, the addition of the aqueous calcium chloride solution is stopped when flocculation occurs in the mixed solution.

[0038] As an embodiment of the present application, after the demulsification is completed, the product after demulsification is sequentially subjected to solid-liquid separation and drying to obtain a rubber reinforcing agent. The present application does not have special limitations on the method of solid-liquid separation, and the solid phase and the liquid phase can be separated by using a method well known in the art. As an embodiment of the present application, the drying is natural air drying.

[0039] The preparation method of the rubber reinforcing agent according to the above technical solution of the present application can further include: The two-dimensional nanomaterial dispersion liquid and the helical nanocarbon fiber dispersion liquid are mixed with the latex respectively, and then demulsification is carried out to obtain rubber-coated two-dimensional nanomaterial and rubber-coated helical nanocarbon fiber respectively. The rubber-coated two-dimensional nanomaterial and the rubber-coated helical nanocarbon fiber are mixed to obtain a rubber reinforcing agent.

[0040] The two-dimensional nanomaterial dispersion liquid and the helical nanocarbon fiber dispersion liquid are mixed with the latex respectively, and then demulsification is carried out to obtain rubber-coated two-dimensional nanomaterial and rubber-coated helical nanocarbon fiber respectively.

[0041] As an embodiment of the present application, the preparation of the two-dimensional nanomaterial dispersion liquid can be mixing the two-dimensional nanomaterial with water to obtain the two-dimensional nanomaterial dispersion liquid. As an embodiment of the present application, the mass ratio of the two-dimensional nanomaterial to water can be 1: (25-1600). In the embodiments of the present application, the mass ratio of the two-dimensional nanomaterial to water can be specifically 1:25, 1:50, 1:100, 1:200, 1:300, 1:400, 1:600, 1:800, 1:1200 or 1:1600. The present application limits the mass ratio of the two-dimensional nanomaterial to water to ensure that the two-dimensional nanomaterial is fully dispersed. As an embodiment of the present application, the mixing of the two-dimensional nanomaterial and water can be carried out under ultrasonic conditions. As an embodiment of the present application, the ultrasonic time can be 1-24h. In the embodiments of the present application, the ultrasonic time can be specifically 1h, 2h, 4h, 8h, 12h, 14h, 16h, 18h, 20h, 22h or 24h.

[0042] As an embodiment of the present application, the preparation method of the helical nanocarbon fiber dispersion liquid is the same as the preparation method of the two-dimensional nanomaterial dispersion liquid, which will not be repeated here.

[0043] As an embodiment of the present application, the type of latex, solid content, mass ratio of two-dimensional nanomaterial dispersion liquid to latex, and mass ratio of helical nanocarbon fiber dispersion liquid to latex are the same as the type of latex, solid content, mass ratio of two-dimensional nanomaterial and helical nanocarbon fiber dispersion liquid to latex, which will not be repeated here.

[0044] As an embodiment of the present application, the operation of demulsification is the same as the demulsification operation described above, which will not be repeated here.

[0045] As an embodiment of the present application, the operation after the completion of demulsification is the same as the operation after the completion of demulsification described above, respectively obtaining rubber-coated two-dimensional nanomaterial and rubber-coated helical nanocarbon fiber, which will not be repeated here.

[0046] After obtaining the rubber-coated two-dimensional nanomaterial and the rubber-coated helical nanocarbon fiber, the present application mixes the rubber-coated two-dimensional nanomaterial and the rubber-coated helical nanocarbon fiber to obtain a rubber reinforcing agent.

[0047] The present application does not have special limitations on the mixing of the rubber-coated two-dimensional nanomaterial and the rubber-coated helical nanocarbon fiber, and any mixing method known in the art can be used.

[0048] The application is beneficial to improve the dispersibility of the two-dimensional nanomaterial and the helical nanometer carbon fiber in the subsequent rubber composite material, and the demulsification process of the application does not need to add an organic solvent, avoids the reduction of the reinforcing effect of the two-dimensional nanomaterial and the helical nanometer carbon fiber caused by organic residues, and the steps are simple and efficient.

[0049] The application further provides a rubber composite material, which comprises, in terms of weight fractions, 96-100 parts of rubber, 1-3 parts of sulfur, 2-7 parts of zinc oxide, 0.3-3 parts of stearic acid, 40-80 parts of white carbon black, 1.5-3 parts of polyethylene glycol 4000, 0.5-2.5 parts of accelerator DM, 0.5-1.5 parts of accelerator M, 0.2-1 part of accelerator DPG, and 0.5-4 parts of a rubber reinforcing agent.

[0050] In the application, the rubber reinforcing agent is the rubber reinforcing agent in the above technical solution or the rubber reinforcing agent prepared by the preparation method in the above technical solution.

[0051] As an embodiment of the application, the rubber composite material provided by the application comprises 96-100 parts of rubber in terms of weight fractions. In the embodiment of the application, the rubber can be 96 parts, 97 parts, 98 parts, 99 parts or 100 parts in terms of weight fractions. The application limits the fraction of the rubber to ensure the stability and repeatability of the performance of the rubber composite material.

[0052] As an embodiment of the application, the rubber composite material provided by the application comprises 1-3 parts of sulfur in terms of weight fractions. In the embodiment of the application, the sulfur can be specifically 1 part, 2 parts or 3 parts in terms of weight fractions. The application adds sulfur as a vulcanizing agent, and converts the rubber molecules from a linear structure to a network structure through cross-linking reaction, thereby improving the mechanical properties, wear resistance and aging resistance of the material.

[0053] As an embodiment of the application, the rubber composite material provided by the application comprises 2-7 parts of zinc oxide in terms of weight fractions. In the embodiment of the application, the zinc oxide can be specifically 2 parts, 3 parts, 4 parts, 5 parts or 7 parts in terms of weight fractions. The application adds zinc oxide to generate zinc salt complexes with accelerators, accelerate vulcanization reaction, and improve cross-linking density and vulcanization efficiency.

[0054] As an embodiment of the present application, the rubber composite material provided by the present application includes stearic acid 0.3-3 parts by weight. In the embodiment of the present application, the stearic acid can be specifically 0.3 parts, 0.8 parts, 1 part, 2 parts or 3 parts by weight. The present application limits the stearic acid to reduce the cohesion between rubber molecules, significantly improve the plasticity of the rubber compound, reduce the viscosity, and react with zinc oxide to form zinc stearate, shorten the vulcanization time and improve the vulcanization efficiency.

[0055] As an embodiment of the present application, the rubber composite material provided by the present application includes white carbon black 40-80 parts by weight. In the embodiment of the present application, the white carbon black can be specifically 40 parts, 50 parts, 60 parts, 70 parts or 80 parts by weight. The present application adds white carbon black to improve the tensile strength, hardness, modulus and wear resistance of rubber, and forms a protective film to slow down the damage of the environment such as ultraviolet rays and high temperature to rubber, prolonging the service life.

[0056] As an embodiment of the present application, the rubber composite material provided by the present application includes polyethylene glycol 4000 1.5-3 parts by weight. In the embodiment of the present application, the polyethylene glycol 4000 can be specifically 1.5 parts, 2 parts, 2.5 parts or 3 parts by weight. The present application limits the polyethylene glycol 4000 to help water discharge during vulcanization, reduce surface defects, neutralize the surface acidity of white carbon black, reduce its adsorption of accelerators, and activate the vulcanization system.

[0057] As an embodiment of the present application, the rubber composite material provided by the present application includes accelerator DM 0.5-2.5 parts by weight. In the embodiment of the present application, the accelerator DM can be specifically 0.5 parts, 1 part, 1.5 parts, 2 parts or 2.5 parts by weight. The present application limits the accelerator DM as a vulcanization accelerator to accelerate the vulcanization reaction, reduce the vulcanization temperature, shorten the vulcanization time, and improve the physical and mechanical properties of the rubber product, and the accelerator M is used in cooperation to further promote the vulcanization speed.

[0058] As an embodiment of the present application, the rubber composite material provided by the present application includes accelerator M 0.5-1.5 parts by weight. In the embodiment of the present application, the accelerator M can be specifically 0.5 parts, 0.8 parts, 1 part, 1.3 parts or 1.5 parts by weight. The present application limits the accelerator M to accelerate the vulcanization reaction, improve the performance of the rubber and prolong the service life.

[0059] As an embodiment of the present application, the rubber composite provided by the present application includes 0.2-1 parts of accelerator DPG by weight fraction. In the embodiment of the present application, the accelerator DPG can be specifically 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts or 1 part by weight fraction. The present application significantly improves the vulcanization speed and shortens the processing time by limiting the accelerator DPG to activate the thiol group; and improves the tensile strength, elongation at break and heat resistance of the rubber composite.

[0060] As an embodiment of the present application, the rubber composite provided by the present application includes 0.5-4 parts of rubber reinforcing agent by weight fraction. In the embodiment of the present application, the rubber reinforcing agent can be specifically 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts or 8 parts by weight fraction. The present application can greatly improve the two-dimensional nanomaterial and the helical nanocarbon fiber by limiting the fraction of the rubber reinforcing agent while adding the two-dimensional nanomaterial and the helical nanocarbon fiber in a small amount.

[0061] The present application does not have special limitations on the preparation method of the rubber composite, and the rubber composite can be prepared by using the preparation method well known in the art.

[0062] The rubber composite provided by the present application has good mechanical properties and low cost, and is suitable for industrial production.

[0063] The technical solutions in the present application will be clearly and completely described below in combination with the embodiments in the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0064] Embodiment 1 A rubber reinforcing agent is: butadiene styrene rubber coated graphene and butadiene styrene rubber coated helical nanocarbon fiber; the number of layers of the graphene is 3-5 layers, the diameter of the graphene is 200 nm; the diameter of the helical nanocarbon fiber is 90 nm, and the structure of the helical nanocarbon fiber can be worm-shaped; the mass ratio of the graphene to butadiene styrene rubber is 1:1, the mass ratio of the helical nanocarbon fiber to butadiene styrene rubber is 1:1; and the mass ratio of the graphene to the helical nanocarbon fiber is 1:2; The preparation method of the above rubber reinforcing agent is: In a beaker, 200 g of deionized water was poured, and then 1 g of graphene was added into the beaker, and ultrasonic was performed for 2 h to obtain a graphene dispersion liquid. Then, 2 g of butadiene styrene rubber latex with a solid content of 50% was added into the beaker, and a stirrer was used to stir at a speed of 250 r / min for 60 min. Then, glacial acetic acid was added dropwise to adjust the pH to 4 during the stirring process. Then, a 10% calcium chloride aqueous solution was added dropwise at a rate of 60 mL / min until flocculation occurred. Then, the obtained product was suction filtered and air dried to obtain butadiene styrene rubber-coated graphene with a coating rate of 95%. The graphene was replaced by 2 g of helical nanocarbon fiber, 200 g of deionized water was replaced by 400 g of deionized water, and 2 g of butadiene styrene rubber latex was replaced by 4 g of butadiene styrene rubber latex. The above steps were repeated to obtain butadiene styrene rubber-coated helical nanocarbon fiber with a coating rate of 95%. The mass ratio of the graphene to the latex was 1:2. The mass ratio of the helical nanocarbon fiber to the latex was 1:2. The 1.33 g of butadiene styrene rubber-coated graphene and 2.67 g of butadiene styrene rubber-coated helical nanocarbon fiber were mixed to obtain 4 g of a rubber reinforcing agent.

[0065] Example 2 A rubber composite material, by weight fraction, was: rubber 98 parts (98 g), sulfur 2 parts (2 g), zinc oxide 5 parts (5 g), stearic acid 1 part (1 g), white carbon black 50 parts (50 g), polyethylene glycol 4000 1.5 parts (1.5 g), accelerator DM 1.2 parts (1.2 g), accelerator M 0.7 parts (0.7 g), accelerator DPG 0.5 parts (0.5 g), rubber reinforcing agent 4 parts (4 g); the rubber reinforcing agent was the rubber reinforcing agent prepared in Example 1; The preparation method of the above rubber composite material was: 98 g of butadiene styrene rubber was wrapped and rolled on a two-roll open mill for 1 min, and then 2 g of sulfur, 5 g of zinc oxide, 1 g of stearic acid, 50 g of white carbon black, 4 g of rubber reinforcing agent, 1.5 g of polyethylene glycol 4000, 1.2 g of accelerator DM, 0.7 g of accelerator M, and 0.5 g of accelerator DPG were added in sequence, and mixed for 5 min. Then, the triangle bag was punched for 10 times, and finally the sheet was taken out. After vulcanization, a rubber composite material was obtained.

[0066] Comparative Example 1 The difference between this comparative example and Example 2 was that the reinforcing agent in Example 2 was replaced by 0.67 g of graphene and 1.33 g of helical nanocarbon fiber, and the rest was the same as Example 2.

[0067] Comparative Example 2 The difference between this comparative example and Example 2 was that the 4 parts (4 g) of rubber reinforcing agent in Example 2 was replaced by 2 parts (2 g), and the rest was the same as Example 2.

[0068] Comparative Example 3 The difference between the present comparative example and Example 2 is that the 4 parts of reinforcing agent in Example 2 is replaced by 4 parts (4 g) of butadiene rubber coated graphene in Example 1, and the rest is the same as Example 2.

[0069] Comparative Example 4 The difference between the present comparative example and Example 2 is that the 4 parts of reinforcing agent in Example 2 is replaced by 4 parts (4 g) of butadiene rubber coated graphene in Example 1, and the rest is the same as Example 2.

[0070] Comparative Example 5 The difference between the present comparative example and Example 2 is that the 4 parts of reinforcing agent in Example 2 is omitted, and the rest is the same as Example 2.

[0071] Comparative Example 6 The difference between the present comparative example and Example 2 is that the reinforcing agent in Example 2 is replaced by 0.67 g of graphene and 1.33 g of carbon nanotubes, and the rest is the same as Example 2.

[0072] The 300% modulus and the tensile strength at break of the rubber composites prepared in Example 1 and Comparative Examples 1-6 were determined by GB / T 528-2009, the tear strength of the rubber composites prepared in Example 1 and Comparative Examples 1-6 was determined by GB / T 529-2008, and the abrasion volume of the rubber composites prepared in Example 1 and Comparative Examples 1-6 was determined by GB / T 9867-2008. The results are shown in Table 1.

[0073] Table 1 Mechanical data of the rubber composites prepared in Example 1 and Comparative Examples 1-6

[0074] As can be seen from Table 1, the 300% modulus, the tensile strength at break and the tear strength of the rubber composite in Example 2 prepared by using the rubber reinforcing agent prepared in Example 1 are all higher than those of the rubber composites prepared in Comparative Examples 1-6, and the abrasion volume of the rubber composite in Example 2 prepared by using the rubber reinforcing agent prepared in Example 1 is lower than that of the rubber composites prepared in Comparative Examples 1-6. It can be seen that the rubber composite prepared by using the rubber reinforcing agent containing trace amounts of graphene and helical nanocarbon fiber provided by the present application has good mechanical properties and good wear resistance.

[0075] The morphology of the graphene in Example 1 was characterized by transmission electron microscopy, and the results are shown in Figure 1 As can be seen from the figure, the graphene has a lamellar structure and exhibits agglomeration, and a few pieces of graphene overlap. If it is not dispersed, its ability to improve the properties of rubber is limited, and even has a negative effect.

[0076] The morphology of the helical nanocarbon fiber in Example 1 was characterized by transmission electron microscopy, and the results are shown in Figure 2 The figure shows that the helical nanocarbon fiber is one-dimensional helical, and this helical structure easily causes the helical nanocarbon fiber to intertwine with each other, which is not easy to disperse in the rubber matrix, and may not significantly improve the rubber performance without dispersion.

[0077] The cross-sectional morphology of the rubber composite material in Example 2 that was broken by the tensile machine was characterized by transmission electron microscopy, and the results are shown in Figure 3 The figure shows that the agglomeration of graphene and helical nanocarbon fiber has been improved, and the dispersed graphene and helical nanocarbon fiber are more easily combined with the white carbon black to form a multi-dimensional filler network, which is beneficial to improve the rubber performance.

[0078] In summary, the rubber reinforcing agent provided by the present application has good reinforcing effect on rubber, the rubber composite material prepared from the rubber reinforcing agent containing trace graphene and helical nanocarbon fiber provided by the present application has good mechanical properties, low cost, and can realize industrialized production.

[0079] The above only describes the preferred embodiments of the present application, and it should be pointed out that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A rubber reinforcing agent, comprising rubber-coated two-dimensional nanomaterials and rubber-coated helical nanocarbon fibers; the two-dimensional nanomaterials in the rubber-coated two-dimensional nanomaterials are graphene or boron nitride nanosheets.

2. The rubber reinforcing agent according to claim 1, characterized in that, The mass ratio of the two-dimensional nanomaterials in the rubber-coated two-dimensional nanomaterials to the helical nanocarbon fibers in the rubber-coated helical nanocarbon fibers is (0.5-2):

1.

3. The rubber reinforcing agent according to claim 1, characterized in that, The rubber in the rubber-coated two-dimensional nanomaterials and the rubber-coated helical nanocarbon fibers is independently selected from natural rubber, styrene-butadiene rubber, cis-butadiene rubber, nitrile rubber, chlorobutyl rubber, ethylene-propylene rubber, butyl rubber and silicone rubber.

4. The rubber reinforcing agent according to any one of claims 1 to 3, characterized in that, The mass ratio of the two-dimensional nanomaterials to the rubber in the rubber-coated two-dimensional nanomaterials and the mass ratio of the helical nanocarbon fibers to the rubber in the rubber-coated helical nanocarbon fibers are independently (1-8):

1. 5.A method for preparing the rubber reinforcing agent of any one of claims 1-4, comprising: mixing a mixed dispersion of two-dimensional nanomaterials and helical nanocarbon fibers with latex and then performing demulsification to obtain the rubber reinforcing agent; or comprising: mixing a two-dimensional nanomaterial dispersion and a helical nanocarbon fiber dispersion with latex respectively and then performing demulsification to obtain rubber-coated two-dimensional nanomaterials and rubber-coated helical nanocarbon fibers; mixing the rubber-coated two-dimensional nanomaterials and the rubber-coated helical nanocarbon fibers to obtain the rubber reinforcing agent.

6. The production method according to claim 5, wherein The mass ratio of the two-dimensional nanomaterials to the latex and the mass ratio of the helical nanocarbon fibers to the latex are independently 1: (0.25-16).

7. The production method according to claim 6, wherein The solid content of the rubber in the latex is 12.5-80%.

8. The preparation method according to claim 5, characterized in that, The demulsification is: adjusting the pH value of the mixed solution obtained by mixing to 4-5, and then adding a calcium chloride aqueous solution.

9. The production method according to claim 5 or 8, characterized by, After the demulsification is completed, the product after demulsification is sequentially subjected to solid-liquid separation and drying.

10. A rubber composite comprising, by weight parts: rubber 96-100 parts, sulfur 1-3 parts, zinc oxide 2-7 parts, stearic acid 0.3-3 parts, white carbon black 40-80 parts, polyethylene glycol 4000 1.5-3 parts, accelerator DM 0.5-2.5 parts, accelerator M 0.5-1.5 parts, accelerator DPG 0.2-1 part, rubber reinforcing agent 0.5-4 parts; the rubber reinforcing agent is the rubber reinforcing agent of any one of claims 1-4 or the rubber reinforcing agent prepared by the method of any one of claims 5-9.

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