A rubber reinforcing agent and a method for producing the same, a rubber composition
A core-shell structured rubber reinforcing agent, consisting of a polydopamine interface layer on the surface of magnesium silicate nanomaterials and a disulfide bond silane coupling agent, prepared by a bio-template method, solves the problems of high heat generation, large rolling resistance, and environmental impact associated with traditional reinforcing agents, achieving high-performance and sustainable rubber reinforcing effects.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANDONG HUASHENG RUBBER
- Filing Date
- 2026-01-08
- Publication Date
- 2026-07-31
AI Technical Summary
Traditional carbon black and silica, when used as rubber reinforcing agents, suffer from problems such as high heat generation, high rolling resistance, poor dispersibility, complex processing, and environmental unfriendliness, making it difficult to achieve both high performance and sustainable development at the same time.
Magnesium silicate nanomaterials were prepared using a biotemplate method. By forming a polydopamine interface layer and a silane coupling agent molecular layer composed of disulfide bonds on its surface, a core-shell structured rubber reinforcing agent was formed. Combined with a multi-level pore design, high reinforcing properties and optimized dynamic performance were ensured.
It achieves high tensile strength and wear resistance, while reducing dynamic heat generation and rolling resistance. It also has flame-retardant and thermally conductive properties and is environmentally friendly, simplifying the formulation and process.
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention relates to the field of reinforcing fillers for the rubber industry, and more specifically to a rubber reinforcing agent and its preparation method, and a rubber composition. Background Technology
[0002] The high performance of rubber products mainly relies on reinforcing fillers, among which carbon black and silica are the most widely used traditional reinforcing agents. However, they also have a series of drawbacks in practical applications. First, carbon black, through its high specific surface area, forms strong physical adsorption and partial chemical bonding with rubber. While this can improve strength, it also leads to significant lag in molecular chain segment movement, resulting in high heat generation and rolling resistance under cyclic dynamic loads. Silica improves some dynamic properties through silane coupling agents, but the mixing process is complex and costly, and its strong polarity and hydrogen bonding can easily lead to filler agglomeration, affecting dispersion uniformity. Second, traditional fillers only provide basic reinforcing effects; if special functions such as flame retardancy and thermal conductivity are required, large amounts of other functional additives must be added. Finally, from a sustainable development perspective, carbon black production is highly dependent on fossil fuels, resulting in severe energy consumption and carbon emission problems; the preparation process of silica also poses environmental pressures. The invention patent application with application number CN202410728274.6 discloses that the silica prepared by the traditional precipitation method has many surface hydroxyl groups, poor structure, and serious agglomeration, resulting in poor dispersibility in rubber and reduced reinforcing effect. Therefore, further improvement and development are needed. Summary of the Invention
[0003] To address the shortcomings of existing technologies and solve the aforementioned problems, a rubber reinforcing agent, its preparation method, and a rubber composition are proposed, along with the following technical solutions: A method for preparing a rubber reinforcing agent includes the following steps: S1. Using a biotemplate method, cellulose nanofibers are used as templates, and magnesium and silicon sources are added for hydrothermal reaction to obtain a magnesium silicate precursor. The magnesium silicate precursor is then calcined to prepare magnesium silicate nanomaterials; S2. The magnesium silicate nanomaterials obtained in step S1 are dispersed in an alkaline buffer solution, and dopamine monomer is added for in-situ oxidative polymerization to form a polydopamine interface layer on its surface, resulting in an MS@PDA intermediate; S3. The MS@PDA intermediate obtained in step S2 is dispersed in an alcohol-water solution, and a silane coupling agent containing dynamic disulfide bonds, bis-[3-(triethoxysilyl)propyl]-disulfide, is added for hydrolysis and condensation reaction to obtain the reinforcing agent product; In step S1, the molar ratio of magnesium to silicon in the magnesium source and silicon source is 1.5:1; In step S2, the mass ratio of magnesium silicate nanomaterials to dopamine monomer is 1:0.5-2.
[0004] Furthermore, the core layer is synthesized by a biotemplate method, the magnesium source is magnesium nitrate, and the silicon source is tetraethyl orthosilicate.
[0005] Furthermore, in step S1, the hydrothermal synthesis is carried out at a temperature of 110-130°C for 4-8 hours; the calcination is carried out under an inert atmosphere at a temperature of 500-600°C for 2-6 hours.
[0006] Furthermore, in step S2, the in-situ oxidative polymerization reaction is carried out in Tris buffer at pH 8.5 for 12-48 hours.
[0007] Furthermore, in step S3, the amount of the silane coupling agent containing dynamic disulfide bonds added is 1%-4% of the mass of the MS@PDA intermediate, and the reaction is carried out under acidic conditions, with a pH of 4-5, a reaction temperature of 60-80°C, and a time of 6-12 hours.
[0008] In addition, the present invention also provides a rubber reinforcing agent prepared by the above preparation method.
[0009] The present invention also provides a rubber composition comprising a rubber matrix and the above-mentioned rubber reinforcing agent, wherein the amount of the reinforcing agent added is 5-100 phr of the mass of the rubber matrix, and the rubber matrix is natural rubber, styrene-butadiene rubber, cis-butadiene rubber, nitrile rubber, chloroprene rubber, ethylene propylene rubber, silicone rubber or a blend thereof.
[0010] Due to the adoption of the above technical solutions, the beneficial technical effects of the present invention are as follows: 1. The unique multi-level channels of the reinforcing agent of this invention can form a physical interlock with the rubber molecular chain, ensuring high reinforcement. At the same time, the silane coupling agent molecular layer composed of polydopamine interface layer and disulfide bond can undergo reversible fracture and reconstruction under external force, efficiently dissipating energy, thereby significantly reducing dynamic heat generation and rolling resistance while maintaining high tensile strength and wear resistance. 2. The magnesium silicate of the present invention has excellent flame retardancy and thermal conductivity, and the polydopamine interface layer can promote char formation, so that the reinforcing rubber can obtain flame retardant and thermal conductivity without a large amount of additional additives, simplifying the formulation and process. 3. The production process of this invention is environmentally friendly. Detailed Implementation
[0011] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Based on the embodiments in this application, other similar embodiments obtained by those skilled in the art without creative effort should all fall within the scope of protection of this application.
[0012] A method for preparing a rubber reinforcing agent: S1. Using cellulose nanofibers as a template, magnesium source and silicon source are added for hydrothermal reaction to obtain magnesium silicate precursor, and magnesium silicate precursor is calcined to prepare magnesium silicate nanomaterials; S2. Magnesium silicate nanomaterials are dispersed in alkaline buffer solution, dopamine monomer is added for in-situ oxidative polymerization to form a polydopamine interface layer on its surface to obtain MS@PDA intermediate; S3. MS@PDA intermediate is dispersed in an alcohol aqueous solution, bis-[3-(triethoxysilyl)propyl]-disulfide is added for hydrolysis condensation reaction; the molar ratio of magnesium element to silicon element in magnesium source and silicon source is 1.5:1; the mass ratio of magnesium silicate nanomaterials to dopamine monomer is 1:0.5-2. The reinforcing agent prepared by this invention is a core-shell structured composite material, comprising: a core layer, an intermediate shell layer, and an outer graft layer. The core layer is a magnesium silicate nanomaterial with a multi-level pore and lamellar interwoven structure. The intermediate shell layer is a polydopamine interface layer wrapped around the surface of the magnesium silicate nanomaterial. The outer graft layer is a silane coupling agent molecular layer grafted onto the polydopamine coating. It has unique multi-level pores and can form physical interlock with the rubber molecular chains to ensure high reinforcement. At the same time, the polydopamine interface layer and the silane coupling agent molecular layer can undergo reversible fracture and reconstruction under external force, efficiently dissipating energy. Thus, while maintaining high tensile strength and wear resistance, it significantly reduces dynamic heat generation and rolling resistance.
[0013] The core layer was synthesized using a biotemplate method, with cellulose nanofibers serving as the biotemplate. Cellulose nanofibers are one-dimensional nanomaterials with extremely high aspect ratios and abundant surface hydroxyl groups. In aqueous solution, they can spontaneously form an interconnected three-dimensional nanofiber network through hydrogen bonding and other interactions. Magnesium silicate precursors preferentially nucleate and grow uniformly on the surface of cellulose nanofibers and in the network pores. After subsequent calcination to remove the cellulose nanofiber template, the remaining magnesium silicate nanomaterials perfectly replicate this three-dimensional network framework, forming a three-dimensional structure composed of interwoven and stacked two-dimensional nanosheets.
[0014] The magnesium silicate nanomaterial has a specific surface area of 200-400 m² / g, and the hierarchical channels include micropores with a pore size of less than 2 nm, mesopores with a pore size of 2-50 nm, and macropores with a pore size of greater than 50 nm.
[0015] Example 1 Step S1: Using cellulose nanofibers (CNF) as a template, magnesium nitrate and tetraethyl orthosilicate (TEOS) were added at a molar ratio of Mg:Si = 1.5:1, with urea as a precipitant. The mixture was hydrothermally reacted at 120°C for 6 hours. The resulting precursor was calcined at 550°C for 4 hours under N2 protection to obtain MS-1. Its specific surface area was 325 m² / g, and the pore size distribution showed: <2 nm micropores, 5-30 nm mesopores, and 100-300 nm macropores.
[0016] Step S2: Disperse 1g of MS-1 in 100mL of Tris buffer at pH=8.5, add dopamine hydrochloride (1g), stir at room temperature for 24 hours to obtain MS-1@PDA.
[0017] Step S3: Disperse 1g of MS-1@PDA in ethanol / water solution, adjust pH=4.5, add 0.1g, 10wt% of bis-[3-(triethoxysilyl)propyl]-disulfide (TESPD), reflux at 70°C for 8 hours to obtain the final reinforcing agent.
[0018] Example 2 Step S1: Using cellulose nanofibers (CNF) as a template, magnesium nitrate and tetraethyl orthosilicate (TEOS) were added at a molar ratio of Mg:Si = 1.5:1, with urea as a precipitant. The mixture was hydrothermally reacted at 110°C for 8 hours. The resulting precursor was calcined at 500°C for 6 hours under N2 protection to obtain MS-2. Its specific surface area was 280 m² / g, and the pore size distribution showed: <2 nm micropores, 5-30 nm mesopores, and 100-300 nm macropores.
[0019] Step S2: Disperse 1g of MS-2 in 100mL of Tris buffer at pH=8.5, add dopamine hydrochloride (0.5g), stir at room temperature for 48 hours to obtain MS-2@PDA.
[0020] Step S3: Disperse 1g of MS-2@PDA in ethanol / water solution, adjust pH=4.5, add 0.5g, 5wt% of bis-[3-(triethoxysilyl)propyl]-disulfide (TESPD), reflux at 60°C for 12 hours to obtain the final reinforcing agent.
[0021] Example 3 Step S1: Using cellulose nanofibers (CNF) as a template, magnesium nitrate and tetraethyl orthosilicate (TEOS) were added at a molar ratio of Mg:Si = 1.5:1, with urea as a precipitant. The mixture was hydrothermally reacted at 130°C for 4 hours. The resulting precursor was calcined at 600°C for 2 hours under N2 protection to obtain MS-3. Its specific surface area was 380 m² / g, and the pore size distribution showed: <2 nm micropores, 5-30 nm mesopores, and 100-300 nm macropores.
[0022] Step S2: Disperse 1g of MS-3 in 100mL of Tris buffer at pH=8.5, add 2g of dopamine hydrochloride, stir at room temperature for 12 hours to obtain MS-3@PDA.
[0023] Step S3: Disperse 1g of MS-3@PDA in ethanol / water solution, adjust pH=4.5, add 0.2g, 20wt% of bis-[3-(triethoxysilyl)propyl]-disulfide (TESPD), reflux at 80°C for 6 hours to obtain the final reinforcing agent.
[0024] Comparative Example 1 Compared to Example 1, only MS-1 prepared in Example 1 was used as a reinforcing agent.
[0025] Comparative Example 2 Compared to Example 1, the MS-1@PDA prepared in Example 1 was used without step S3 as a reinforcing agent.
[0026] Comparative Example 3 Compared to Example 1, in step S1, ordinary cellulose microcrystals (MCC) were used instead of CNF as a template, while other steps remained the same as in Example 1, resulting in MS-MCC with a specific surface area of only 150 m² / g, mainly consisting of macropores and lacking fine mesopores. Subsequent steps were the same as in Example 1.
[0027] Comparative Example 4 Use commercially available N330 carbon black.
[0028] Comparative Example 5 Commercially available highly dispersible silica (Zeosil 1165MP) was used in combination with silane coupling agent Si69.
[0029] Comparative Example 6 Compared with Example 1, KH-550 is used instead of TESPD in step S3, and the rest is the same as in Example 1.
[0030] Forty portions of the rubber reinforcing agents from Examples 1-3 and Comparative Examples 1-6 were added to natural rubber and mixed and vulcanized according to standard procedures to obtain corresponding rubber test samples. The corresponding rubber test samples were tested for mechanical properties, dynamic heat generation, abrasion resistance, etc., according to relevant testing standards. The test results are shown in Table 1. Tensile strength: tested according to GB / T528-2009, sample size dumbbell shape, speed 500 mm / min. Tear strength: tested according to GB / T 529-2008. Abrasion resistance: tested according to GB / T 9867-2008, expressed as abrasion loss. Dynamic heat generation: tested according to GB / T1687.3-2016. Limiting oxygen index: tested according to GB / T 5454-1997. Thermal conductivity: tested according to ASTM-D5470.
[0031] Table 1. Test results of rubber samples prepared with rubber reinforcing agents from Examples 1-3 and Comparative Examples 1-6. As can be seen from the data in the table above, the rubber reinforcing agent prepared by this invention, through its unique structural design, with the core layer, intermediate shell layer, and outer graft layer working synergistically, improves its mechanical properties, wear resistance, flame retardancy, and thermal conductivity. Specifically, Example 1 achieves the highest tensile strength of 28.5 MPa, while its tan δ at 60°C decreases to the lowest of 0.085. Typically, increasing strength sacrifices dynamic performance; for example, the carbon black in Comparative Example 4 has high strength but also high tan δ. This indicates that this application significantly reduces dynamic heat generation while maintaining high tensile strength. Comparative Examples 1 and 3 exhibit poor reinforcing effects, dynamic heat generation, and wear resistance, which is related to the lack of hierarchical channels or polydopamine interface layers in Comparative Examples 1 and 3. This also demonstrates the technical effect brought about by the structural design of this application. The limiting oxygen index of Example 1 far exceeds that of the carbon black in Comparative Example 4 and the silica in Comparative Example 5, approaching the level of flame-retardant materials. This is directly due to the synergistic flame-retardant effect of magnesium silicate and PDA, achieving integrated reinforcement and flame retardancy. Example 1 exhibits a significantly higher thermal conductivity than carbon black and silica, which is beneficial for heat dissipation in products such as tires, thus improving safety and lifespan. Examples 2 and 3, adjusted within their respective ranges, demonstrate superior performance compared to the comparative examples. Furthermore, Comparative Example 3, using a different template, resulted in deterioration of the pore structure and decreased performance, illustrating the need for CNF as a template to construct fine, multi-level channels in this application.
[0032] The self-healing performance of the rubber samples mentioned above was also tested. After microcracks appeared in the samples, they were heat-treated at 80 degrees Celsius for 2 hours. The strength retention rate after self-healing in Example 1 was 65%, in Comparative Example 2 it was 55%, and in Comparative Example 6 it was 30%. After grafting disulfide bonds, the self-healing ability was significantly enhanced. The wear of Example 1 was much lower than that of Comparative Example 1 and Comparative Example 4, and even better than that of high-performance silica. This is because the dynamic interface continuously consumes energy during the wear process, which delays crack propagation.
[0033] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A method for preparing a rubber reinforcing agent, characterized in that, Includes the following steps: S1. Using the biotemplate method, cellulose nanofibers were used as templates, and magnesium and silicon sources were added to carry out a hydrothermal reaction to obtain magnesium silicate precursors. Magnesium silicate nanomaterials were prepared by calcining the magnesium silicate precursors. S2. The magnesium silicate nanomaterials obtained in step S1 are dispersed in an alkaline buffer solution, and dopamine monomers are added for in-situ oxidative polymerization to form a polydopamine interface layer on its surface, thus obtaining the MS@PDA intermediate. S3. The MS@PDA intermediate obtained in step S2 is dispersed in an alcohol-water solution, and a silane coupling agent containing dynamic disulfide bonds, bis-[3-(triethoxysilyl)propyl]-disulfide, is added to carry out a hydrolysis-condensation reaction to obtain the reinforcing agent product; In step S1, the molar ratio of magnesium to silicon in the magnesium source and silicon source is 1.5:
1. In step S2, the mass ratio of the magnesium silicate nanomaterial to the dopamine monomer is 1:0.5-2.
2. The method for preparing the rubber reinforcing agent according to claim 1, characterized in that, The magnesium source is magnesium nitrate, and the silicon source is tetraethyl orthosilicate.
3. The method for preparing the rubber reinforcing agent according to claim 1, characterized in that, In step S1, the hydrothermal synthesis is carried out at a temperature of 110-130°C for 4-8 hours; the calcination is carried out under an inert atmosphere at a temperature of 500-600°C for 2-6 hours.
4. The method for preparing the rubber reinforcing agent according to claim 1, characterized in that, In step S2, the in-situ oxidative polymerization reaction is carried out in Tris buffer at pH 8.5 for 12-48 hours.
5. The method for preparing the rubber reinforcing agent according to claim 1, characterized in that, In step S3, the amount of the silane coupling agent containing dynamic disulfide bonds added is 1%-4% of the mass of the MS@PDA intermediate. The reaction is carried out under acidic conditions, with a pH of 4-5, a reaction temperature of 60-80°C, and a reaction time of 6-12 hours.
6. A rubber reinforcing agent prepared by the method of any one of claims 1-5.
7. A rubber composition, characterized in that, The product comprises a rubber matrix and a rubber reinforcing agent as described in claim 6, wherein the amount of the reinforcing agent added is 5-100 phr of the rubber matrix mass, and the rubber matrix is one or a combination of two or more of natural rubber, styrene-butadiene rubber, cis-butadiene rubber, nitrile rubber, chloroprene rubber, ethylene propylene rubber, and silicone rubber.