A crosslinking agent, its preparation method and use in the preparation of rubber

Abstract

This invention relates to the field of crosslinking agent preparation technology for rubber, specifically to a crosslinking agent, its preparation method, and its application in rubber preparation. The crosslinking agent of this invention is prepared through multi-level structural design and functional modification: first, a porous support is synthesized using a template method, then modified with vinylsilane alkenylation, loaded with a divinylbenzene crosslinking agent, and then crosslinked using Fe... 3+ The crosslinking agent utilizes tannic acid coordination to form an inner encapsulation layer, undergoes surface functionalization modification with 1,9-decadiene, and is finally physically coated with low-melting-point paraffin wax on the outer layer. This crosslinking agent exhibits unique "dual-threshold gated" release characteristics: the outer paraffin layer provides physical protection at mixing temperatures, while the inner coordination network can be controllably dissociated at vulcanization temperatures, enabling the on-demand release of the crosslinking active components. Its application in rubber preparation significantly improves the uniformity of the crosslinking network, increases crosslinking efficiency, and solves problems such as premature consumption and uneven distribution of traditional crosslinking agents.

Description

Technical Field

[0001] This invention relates to the field of crosslinking agent preparation technology for rubber, specifically to a crosslinking agent, its preparation method, and its application in rubber preparation. Background Technology

[0002] As an important industrial material, the mechanical properties, durability, and fatigue resistance of rubber products directly determine their service life and application range. Traditional rubber formulations typically rely on conventional fillers such as carbon black and sulfur vulcanization systems to construct cross-linked networks. For example, the rubber for automobile tires disclosed in patent document CN109320792A is mainly made from the following raw materials: natural rubber, carbon black, brominated butyl rubber, sulfur, styrene-butadiene rubber, graphite, viscose fiber, dicumyl peroxide, metakaolin, benzoic acid, bamboo fiber, hydroxyl silicone oil, stearyl alcohol, montmorillonite, cis-butadiene rubber, paraffin oil, talc, antioxidant, accelerator, and maleic anhydride.

[0003] However, this conventional system has many limitations. First, during the mixing process, the crosslinking agent is prone to premature consumption or uneven distribution due to high temperature and shear, resulting in defects in the crosslinking network in the final vulcanized product. This manifests as excessively high or low local crosslinking density. This unevenness significantly reduces the tensile strength of the material and becomes a stress concentration point, accelerating the initiation and propagation of fatigue cracks under dynamic loads. Second, the release and reaction of conventional vulcanizing agents are difficult to control precisely, often leading to crosslinking reactions occurring too early or too late, failing to achieve optimal matching with the movement state of the rubber molecular chains. This not only affects the crosslinking efficiency but also causes irreversible slippage and rearrangement of the molecular chains under stress, resulting in increased compression set. The product is difficult to restore its original shape after long-term use, and its dimensional stability deteriorates. Furthermore, the interfacial bonding force between the filler and the rubber matrix is ​​often insufficient. Under repeated friction and stress, filler particles are prone to detach from the matrix, leading to accelerated wear and decreased wear resistance. In addition, in order to achieve specific processing characteristics, a large amount of processing aids are often required. These aids may migrate to the surface of the product, affecting its appearance and performance, and even causing compatibility problems.

[0004] Therefore, there is an urgent need for a crosslinking agent that can remain stable during the rubber mixing stage and be released as needed during the vulcanization stage, thereby forming a uniform, strong and stable three-dimensional network structure in the rubber matrix, fundamentally improving the overall performance of rubber products. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a crosslinking agent, its preparation method, and its application in rubber preparation, so as to solve the problems of uneven crosslinking network, easy premature consumption, weak interfacial bonding, and poor dynamic performance in existing rubber crosslinking technologies.

[0006] To achieve the above objectives, the present invention provides a method for preparing a crosslinking agent, the specific preparation steps of which are as follows:

[0007] S1 Preparation of porous support: Hydrochloric acid and Pluronic P123 were mixed and magnetically stirred at 40℃ for 30 min to dissolve. Then, tetraethyl orthosilicate was added dropwise and stirring was continued for 2 h. Next, 1,3,5-trimethylbenzene was added and tetraethyl orthosilicate was added. The temperature was raised to 60℃ and held for 2-3 h. Then, the reaction system was transferred to a hydrothermal reactor with a polytetrafluoroethylene liner and aged at 90-100℃ for 20-24 h. After the reaction was completed, the mixture was filtered, washed with water until neutral, vacuum dried, and calcined to obtain the porous support.

[0008] S2 Preparation of alkenylated porous support: The porous support was dispersed in anhydrous toluene, vinyltriethoxysilane and triethylamine were added, and the mixture was refluxed at 105-110℃ for 3 h. The resulting product was centrifuged, filtered, washed, and vacuum dried to obtain the alkenylated porous support.

[0009] S3 Preparation of porous support loaded with crosslinking agent: Divinylbenzene is dissolved in n-hexane, and an alkenylated porous support is added. The mixture is evacuated to 0.08 MPa at room temperature for 30-60 min, then restored to normal pressure and stirred for 1-2 h. The mixture is then rotary evaporated and vacuum dried to obtain the porous support loaded with crosslinking agent.

[0010] S4 Preparation of Fe 3+ Complex-modified porous support for crosslinking agent: Tannic acid, ethanol, and deionized water were mixed evenly, and then the porous support for crosslinking agent was added. The mixture was stirred under vacuum at 0.06-0.08 MPa for 5-10 min at room temperature. Then, ferric chloride solution was added dropwise, and stirring was continued for 30-60 min. After the reaction was completed, the mixture was washed and dried under vacuum to obtain Fe. 3+ Complexes modify porous carriers loaded with crosslinking agents;

[0011] S5 Preparation of Functionalized Porous Supports: 1,9-decadiene was dissolved in n-hexane, and Fe was added. 3+ The porous support modified with the complex and loaded with the crosslinking agent was impregnated at room temperature under vacuum to 0.08 MPa for 10-15 min, then stirred at normal pressure for 30 min, rotary evaporated, and vacuum dried to obtain the functionalized porous support.

[0012] S6 Preparation of crosslinking agent: Dissolve low melting point paraffin in white oil, keep warm at 50-60℃ to form a uniform solution, add functionalized porous carrier, roll-coat / stir for 10-15 min, let stand at room temperature to evaporate white oil, and then vacuum dry at 50℃ for 4 h to obtain crosslinking agent.

[0013] Preferably, the ratio of hydrochloric acid, Pluronic P123, tetraethyl orthosilicate, and 1,3,5-trimethylbenzene used in step S1 is 180-220 mL: 3.5-4.5 g: 10-12 g: 1.5-2.5 g.

[0014] Preferably, the concentration of hydrochloric acid in step S1 is 2M.

[0015] Preferably, the calcination temperature in step S1 is 550-600℃, and the calcination time is 6h.

[0016] Preferably, the ratio of the porous support, anhydrous toluene, vinyltriethoxysilane, and triethylamine in step S2 is 4-6g:80-100mL:0.6-1g:0.08-0.1g.

[0017] Preferably, the ratio of divinylbenzene, n-hexane, and alkenylated porous support used in step S3 is 2.2-2.5g:30-35mL:2.5-3.5g.

[0018] Preferably, the ratio of tannic acid, ethanol, deionized water, porous carrier loaded with crosslinking agent, and ferric chloride solution in step S4 is 0.4-0.6g:25-30mL:25-30mL:2.5-3.5g:10-15mL.

[0019] Preferably, the concentration of the ferric chloride solution in step S4 is 0.1 mol / L.

[0020] Preferably, the 1,9-decadiene, n-hexane, and Fe in step S5 3+ The ratio of the amount of complex-modified porous carrier loaded with crosslinking agent is 1-1.5g: 20-30mL: 2.5-3.5g.

[0021] Preferably, the ratio of low-melting-point paraffin, white oil, and functionalized porous carrier in step S6 is 0.8-1g:20-25mL:2.5-3.5g.

[0022] Preferably, the low-melting-point paraffin wax Tm in step S6 is 58-62℃.

[0023] Preferably, the present invention also provides a crosslinking agent.

[0024] Furthermore, the present invention also provides an application of a crosslinking agent in rubber preparation.

[0025] The beneficial effects of this invention are:

[0026] The crosslinking agent of this invention, through innovative design, possesses multi-level encapsulation and controllable release characteristics. Through the core porous carrier structure, chemical modification of the interface, coordination encapsulation of the inner layer, and physical coating of the outer layer, multiple synergistic effects are achieved. This effectively protects the active components of the crosslinking agent during the mixing process, avoiding premature reaction and ineffective consumption. It ensures that sufficient and uniformly distributed active sites participate in the construction of the three-dimensional network during the vulcanization stage. The resulting crosslinking point distribution is more dense and uniform, greatly improving the connection strength between molecular chains. This allows the material to more effectively disperse and transfer stress, thereby exhibiting excellent tensile strength, tear resistance, and long service life.

[0027] The crosslinking agent of this invention achieves stepped release of "outer layer low threshold gate" and "inner layer high threshold gate" by locally encapsulating Fe³⁺-tannic acid complex on the surface of a porous carrier, followed by subsequent low-melting-point paraffin encapsulation. This avoids the loss and uneven distribution problems of traditional crosslinking agents during processing, ensuring that the crosslinking agent can be continuously and uniformly released throughout the vulcanization crosslinking process, thereby significantly improving the crosslinking efficiency and the uniformity of the crosslinking network.

[0028] The crosslinking agent of the present invention, by anchoring divinylbenzene in the inner layer of a porous carrier and loading 1,9-decadiene in the shell layer, allows the surface 1,9-decadiene to participate in plasticization as a small molecule, thereby improving compatibility, while the divinylbenzene, as a large molecule, participates in the subsequent vulcanization crosslinking, making the crosslinking effect of the crosslinking agent more excellent. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0030] Preparation Example 1: A crosslinking agent, the specific preparation steps are as follows:

[0031] (1) Mix 180 mL of 2M hydrochloric acid and 3.5 g of Pluronic P123, stir magnetically at 40 °C for 30 min, then add 5 g of tetraethyl orthosilicate, continue stirring for 2 h, then add 1.5 g of 1,3,5-trimethylbenzene, and add 5 g of tetraethyl orthosilicate, heat to 60 °C and keep warm for 2 h, then transfer the reaction system to a hydrothermal reactor lined with polytetrafluoroethylene, age at 90 °C for 20 h, after the reaction is completed, filter, wash with water until neutral, and vacuum dry at 60 °C for 12 h, and finally calcine at 550 °C for 6 h to obtain a porous support;

[0032] (2) 4g of porous support was dispersed in 80mL of anhydrous toluene, 0.6g of vinyltriethoxysilane and 0.08g of triethylamine were added, and the mixture was refluxed at 105℃ for 3h. The product was centrifuged, filtered, washed with toluene, and dried under vacuum at 60℃ for 12h to obtain the alkenylated porous support.

[0033] (3) Dissolve 2.2g of divinylbenzene in 30mL of n-hexane, add 2.5g of alkenylated porous support, evacuate to 0.08MPa at room temperature for 30min, restore normal pressure and continue stirring for 1h, rotary evaporate, and finally vacuum dry at 40℃ for 4h to obtain a porous support loaded with crosslinking agent.

[0034] (4) Mix 0.4 g tannic acid, 25 mL ethanol, and 25 mL deionized water thoroughly, then add 2.5 g of porous carrier loaded with crosslinking agent. Stir at 0.06 MPa for 5 min under vacuum at room temperature. Then add 10 mL of 0.1 mol / L ferric chloride solution dropwise and continue stirring for 30 min. After the reaction is complete, quickly wash with ethanol and dry under vacuum at 50 °C for 6 h to obtain Fe. 3+ Complexes modify porous carriers loaded with crosslinking agents;

[0035] (5) Dissolve 1 g of 1,9-decadiene in 20 mL of n-hexane, and add 2.5 g of Fe. 3+ The porous support modified with the complex and loaded with the crosslinking agent was impregnated at room temperature to 0.08 MPa for 10 min, then stirred at normal pressure for 30 min, rotary evaporated, and finally vacuum dried at 40℃ for 4 h to obtain the functionalized porous support.

[0036] (6) Dissolve 0.8g of low-melting-point paraffin in 20mL of white oil, keep warm at 50℃ to form a uniform solution, add 2.5g of functionalized porous carrier, roll / stir for 10min, let stand at room temperature to evaporate the white oil, and then vacuum dry at 50℃ for 4h to obtain crosslinking agent.

[0037] Preparation Example 2: A crosslinking agent, the specific preparation steps are as follows:

[0038] (1) Mix 200 mL of 2M hydrochloric acid and 4 g of Pluronic P123, stir magnetically at 40 °C for 30 min, then add 5.5 g of tetraethyl orthosilicate, continue stirring for 2 h, then add 2 g of 1,3,5-trimethylbenzene, and add 5.5 g of tetraethyl orthosilicate, heat to 60 °C and keep warm for 3 h, then transfer the reaction system to a hydrothermal reactor lined with polytetrafluoroethylene, age at 95 °C for 23 h, after the reaction is completed, filter, wash with water until neutral, and vacuum dry at 60 °C for 12 h, and finally calcine at 560 °C for 6 h to obtain a porous support;

[0039] (2) 5g of porous support was dispersed in 90mL of anhydrous toluene, 0.8g of vinyltriethoxysilane and 0.09g of triethylamine were added, and the mixture was refluxed at 105℃ for 3h. The resulting product was centrifuged, filtered, washed with toluene, and dried under vacuum at 60℃ for 12h to obtain alkenylated porous support.

[0040] (3) Dissolve 2.4g of divinylbenzene in 35mL of n-hexane, add 3g of alkenylated porous support, evacuate to 0.08MPa at room temperature for 50min, restore normal pressure and continue stirring for 2h, rotary evaporate, and finally vacuum dry at 40℃ for 4h to obtain a porous support loaded with crosslinking agent.

[0041] (4) Mix 0.5g tannic acid, 30mL ethanol, and 30mL deionized water thoroughly, then add 3g of porous carrier loaded with crosslinking agent. Stir at 0.07MPa vacuum for 10min at room temperature, then add 13mL of 0.1mol / L ferric chloride solution dropwise and continue stirring for 50min. After the reaction is complete, quickly wash with ethanol and dry under vacuum at 50℃ for 6h to obtain Fe. 3+ Complexes modify porous carriers loaded with crosslinking agents;

[0042] (5) Dissolve 1.3g of 1,9-decadiene in 25mL of n-hexane, and add 3g of Fe. 3+ The porous support modified with the complex and loaded with the crosslinking agent was impregnated at room temperature to 0.08 MPa for 13 min, then stirred at normal pressure for 30 min, rotary evaporated, and finally vacuum dried at 40℃ for 4 h to obtain the functionalized porous support.

[0043] (6) Dissolve 0.9g of low-melting-point paraffin in 23mL of white oil, keep warm at 55℃ to form a uniform solution, add 3g of functionalized porous carrier, roll / stir for 13min, let stand at room temperature to evaporate the white oil, and then vacuum dry at 50℃ for 4h to obtain crosslinking agent.

[0044] Preparation Example 3: A crosslinking agent, the specific preparation steps are as follows:

[0045] (1) Mix 220 mL of 2M hydrochloric acid and 4.5 g of Pluronic P123, stir magnetically at 40 °C for 30 min, then add 6 g of tetraethyl orthosilicate, continue stirring for 2 h, then add 2.5 g of 1,3,5-trimethylbenzene, and add 6 g of tetraethyl orthosilicate, heat to 60 °C and keep warm for 3 h, then transfer the reaction system to a hydrothermal reactor lined with polytetrafluoroethylene, age at 100 °C for 24 h, after the reaction is completed, filter, wash with water until neutral, and vacuum dry at 60 °C for 12 h, and finally calcine at 600 °C for 6 h to obtain a porous support;

[0046] (2) 6g of porous support was dispersed in 100mL of anhydrous toluene, 1g of vinyltriethoxysilane and 0.1g of triethylamine were added, and the mixture was refluxed at 110℃ for 3h. The resulting product was centrifuged, filtered, washed with toluene, and dried under vacuum at 60℃ for 12h to obtain alkenylated porous support.

[0047] (3) Dissolve 2.5g of divinylbenzene in 35mL of n-hexane, add 3.5g of alkenylated porous support, evacuate to 0.08MPa at room temperature for 60min, restore normal pressure and continue stirring for 2h, rotary evaporate, and finally vacuum dry at 40℃ for 4h to obtain a porous support loaded with crosslinking agent.

[0048] (4) Mix 0.6 g tannic acid, 30 mL ethanol, and 30 mL deionized water thoroughly, then add 3.5 g of porous carrier loaded with crosslinking agent. Stir at 0.08 MPa under vacuum for 10 min at room temperature. Then add 15 mL of 0.1 mol / L ferric chloride solution dropwise and continue stirring for 60 min. After the reaction is complete, quickly wash with ethanol and dry under vacuum at 50 °C for 6 h to obtain Fe. 3+ Complexes modify porous carriers loaded with crosslinking agents;

[0049] (5) Dissolve 1.5g of 1,9-decadiene in 30mL of n-hexane, and add 3.5g of Fe. 3+ The porous carrier modified with the complex and loaded with the crosslinking agent was impregnated at room temperature to 0.08 MPa for 15 min, then stirred at normal pressure for 30 min, rotary evaporated, and finally vacuum dried at 40℃ for 4 h to obtain the functionalized porous carrier.

[0050] (6) Dissolve 1g of low-melting-point paraffin in 25mL of white oil, keep warm at 60℃ to form a uniform solution, add 3.5g of functionalized porous carrier, roll / stir for 15min, let stand at room temperature to evaporate the white oil, and then vacuum dry at 50℃ for 4h to obtain crosslinking agent.

[0051] Example 1: A method for preparing rubber, wherein the crosslinking agent used is the one obtained in Preparation Example 1, and the specific preparation steps are as follows:

[0052] 70 parts SBR, 30 parts BR, 60 parts precipitated silica, 6 parts silane coupling agent TESPT, 5 parts softening oil, 3 parts ZnO, 2 parts stearic acid, and 2 parts antioxidant were placed in an internal mixer and mixed at 140°C to form sheets. After standing to room temperature, the resulting rubber compound was warmed to 70°C and mixed again with 8 parts crosslinking agent, 1.6 parts sulfur, and 1.2 parts TBBS. The temperature was raised to 95°C and held for 2 minutes. Finally, it was held at 170°C for 10 minutes to obtain rubber.

[0053] Example 2: A method for preparing rubber, using the crosslinking agent obtained in Example 2, and the specific preparation steps are as follows:

[0054] 70 parts SBR, 30 parts BR, 60 parts precipitated silica, 6 parts silane coupling agent TESPT, 5 parts softening oil, 3 parts ZnO, 2 parts stearic acid, and 2 parts antioxidant were placed in an internal mixer and mixed at 145°C to form sheets. After standing to room temperature, the resulting rubber compound was warmed to 70°C and mixed again with 8 parts crosslinking agent, 1.6 parts sulfur, and 1.2 parts TBBS. The temperature was raised to 100°C and held for 2 minutes, and finally held at 175°C for 12 minutes to obtain rubber.

[0055] Example 3: A method for preparing rubber, using the crosslinking agent obtained in Example 3, and the specific preparation steps are as follows:

[0056] 70 parts SBR, 30 parts BR, 60 parts precipitated silica, 6 parts silane coupling agent TESPT, 5 parts softening oil, 3 parts ZnO, 2 parts stearic acid, and 2 parts antioxidant were placed in an internal mixer and mixed at 150°C to form sheets. After standing to room temperature, the resulting rubber compound was warmed to 70°C and mixed again with 8 parts crosslinking agent, 1.6 parts sulfur, and 1.2 parts TBBS. The temperature was raised to 105°C and held for 3 minutes, and finally held at 175°C for 12 minutes to obtain rubber.

[0057] Comparative Example 1: The difference from Example 2 is that the crosslinking agent used does not undergo alkenylation treatment. The specific steps are as follows:

[0058] (1) Mix 200 mL of 2M hydrochloric acid and 4 g of Pluronic P123, stir magnetically at 40 °C for 30 min, then add 5.5 g of tetraethyl orthosilicate, continue stirring for 2 h, then add 2 g of 1,3,5-trimethylbenzene, and add 5.5 g of tetraethyl orthosilicate, heat to 60 °C and keep warm for 3 h, then transfer the reaction system to a hydrothermal reactor lined with polytetrafluoroethylene, age at 95 °C for 23 h, after the reaction is completed, filter, wash with water until neutral, and vacuum dry at 60 °C for 12 h, and finally calcine at 560 °C for 6 h to obtain a porous support;

[0059] (2) Dissolve 2.4g of divinylbenzene in 35mL of n-hexane, add 3g of porous support, evacuate to 0.08MPa at room temperature for 50min, restore normal pressure and continue stirring for 2h, rotary evaporate, and finally vacuum dry at 40℃ for 4h to obtain a porous support loaded with crosslinking agent.

[0060] (3) Mix 0.5g tannic acid, 30mL ethanol, and 30mL deionized water evenly, then add 3g of porous carrier loaded with crosslinking agent, and stir under vacuum at 0.07MPa for 10min at room temperature. Then add 13mL of 0.1mol / L ferric chloride solution dropwise, and continue stirring for 50min. After the reaction is complete, quickly wash with ethanol and dry under vacuum at 50℃ for 6h to obtain Fe. 3+Complexes modify porous carriers loaded with crosslinking agents;

[0061] (4) Dissolve 1.3g of 1,9-decadiene in 25mL of n-hexane, and add 3g of Fe. 3+ The porous support modified with the complex and loaded with the crosslinking agent was impregnated at room temperature to 0.08 MPa for 13 min, then stirred at normal pressure for 30 min, rotary evaporated, and finally vacuum dried at 40℃ for 4 h to obtain the functionalized porous support.

[0062] (5) Dissolve 0.9g of low-melting-point paraffin in 23mL of white oil, keep warm at 55℃ to form a uniform solution, add 3g of functionalized porous carrier, roll / stir for 13min, let stand at room temperature to evaporate the white oil, and then vacuum dry at 50℃ for 4h to obtain crosslinking agent.

[0063] Comparative Example 2: The difference from Example 2 is that the crosslinking agent used does not undergo Fe... 3+ The specific steps for complex modification are as follows:

[0064] (1) Mix 200 mL of 2M hydrochloric acid and 4 g of Pluronic P123, stir magnetically at 40 °C for 30 min, then add 5.5 g of tetraethyl orthosilicate, continue stirring for 2 h, then add 2 g of 1,3,5-trimethylbenzene, and add 5.5 g of tetraethyl orthosilicate, heat to 60 °C and keep warm for 3 h, then transfer the reaction system to a hydrothermal reactor lined with polytetrafluoroethylene, age at 95 °C for 23 h, after the reaction is completed, filter, wash with water until neutral, and vacuum dry at 60 °C for 12 h, and finally calcine at 560 °C for 6 h to obtain a porous support;

[0065] (2) 5g of porous support was dispersed in 90mL of anhydrous toluene, 0.8g of vinyltriethoxysilane and 0.09g of triethylamine were added, and the mixture was refluxed at 105℃ for 3h. The resulting product was centrifuged, filtered, washed with toluene, and dried under vacuum at 60℃ for 12h to obtain alkenylated porous support.

[0066] (3) Dissolve 2.4g of divinylbenzene in 35mL of n-hexane, add 3g of alkenylated porous support, evacuate to 0.08MPa at room temperature for 50min, restore normal pressure and continue stirring for 2h, rotary evaporate, and finally vacuum dry at 40℃ for 4h to obtain a porous support loaded with crosslinking agent.

[0067] (4) Dissolve 1.3g of 1,9-decadiene in 25mL of n-hexane, add 3g of porous carrier loaded with crosslinking agent, evacuate to 0.08MPa at room temperature for 13min, restore normal pressure and stir for 30min, rotary evaporate, and finally vacuum dry at 40℃ for 4h to obtain functionalized porous carrier.

[0068] (5) Dissolve 0.9g of low-melting-point paraffin in 23mL of white oil, keep warm at 55℃ to form a uniform solution, add 3g of functionalized porous carrier, roll / stir for 13min, let stand at room temperature to evaporate the white oil, and then vacuum dry at 50℃ for 4h to obtain crosslinking agent.

[0069] Comparative Example 3: The difference from Example 2 is that the crosslinking agent used is not 1,9-decadiene for further modification. The specific steps are as follows:

[0070] (1) Mix 200 mL of 2M hydrochloric acid and 4 g of Pluronic P123, stir magnetically at 40 °C for 30 min, then add 5.5 g of tetraethyl orthosilicate, continue stirring for 2 h, then add 2 g of 1,3,5-trimethylbenzene, and add 5.5 g of tetraethyl orthosilicate, heat to 60 °C and keep warm for 3 h, then transfer the reaction system to a hydrothermal reactor lined with polytetrafluoroethylene, age at 95 °C for 23 h, after the reaction is completed, filter, wash with water until neutral, and vacuum dry at 60 °C for 12 h, and finally calcine at 560 °C for 6 h to obtain a porous support;

[0071] (2) 5g of porous support was dispersed in 90mL of anhydrous toluene, 0.8g of vinyltriethoxysilane and 0.09g of triethylamine were added, and the mixture was refluxed at 105℃ for 3h. The resulting product was centrifuged, filtered, washed with toluene, and dried under vacuum at 60℃ for 12h to obtain alkenylated porous support.

[0072] (3) Dissolve 2.4g of divinylbenzene in 35mL of n-hexane, add 3g of alkenylated porous support, evacuate to 0.08MPa at room temperature for 50min, restore normal pressure and continue stirring for 2h, rotary evaporate, and finally vacuum dry at 40℃ for 4h to obtain a porous support loaded with crosslinking agent.

[0073] (4) Mix 0.5g tannic acid, 30mL ethanol, and 30mL deionized water thoroughly, then add 3g of porous carrier loaded with crosslinking agent. Stir at 0.07MPa vacuum for 10min at room temperature, then add 13mL of 0.1mol / L ferric chloride solution dropwise and continue stirring for 50min. After the reaction is complete, quickly wash with ethanol and dry under vacuum at 50℃ for 6h to obtain Fe. 3+ Complexes modify porous carriers loaded with crosslinking agents;

[0074] (5) Dissolve 0.9g of low-melting-point paraffin in 23mL of white oil, keep warm at 55℃ to form a homogeneous solution, and add 3g of Fe. 3+ The porous carrier loaded with the crosslinking agent was modified with a complex, and then coated / stirred for 13 min. After the white oil evaporated by standing at room temperature, it was dried under vacuum at 50 °C for 4 h to obtain the crosslinking agent.

[0075] Comparative Example 4: The difference from Example 2 is that the crosslinking agent used does not use paraffin coating. The specific steps are as follows:

[0076] (1) Mix 200 mL of 2M hydrochloric acid and 4 g of Pluronic P123, stir magnetically at 40 °C for 30 min, then add 5.5 g of tetraethyl orthosilicate, continue stirring for 2 h, then add 2 g of 1,3,5-trimethylbenzene, and add 5.5 g of tetraethyl orthosilicate, heat to 60 °C and keep warm for 3 h, then transfer the reaction system to a hydrothermal reactor lined with polytetrafluoroethylene, age at 95 °C for 23 h, after the reaction is completed, filter, wash with water until neutral, and vacuum dry at 60 °C for 12 h, and finally calcine at 560 °C for 6 h to obtain a porous support;

[0077] (2) 5g of porous support was dispersed in 90mL of anhydrous toluene, 0.8g of vinyltriethoxysilane and 0.09g of triethylamine were added, and the mixture was refluxed at 105℃ for 3h. The resulting product was centrifuged, filtered, washed with toluene, and dried under vacuum at 60℃ for 12h to obtain alkenylated porous support.

[0078] (3) Dissolve 2.4g of divinylbenzene in 35mL of n-hexane, add 3g of alkenylated porous support, evacuate to 0.08MPa at room temperature for 50min, restore normal pressure and continue stirring for 2h, rotary evaporate, and finally vacuum dry at 40℃ for 4h to obtain a porous support loaded with crosslinking agent.

[0079] (4) Mix 0.5g tannic acid, 30mL ethanol, and 30mL deionized water thoroughly, then add 3g of porous carrier loaded with crosslinking agent. Stir at 0.07MPa vacuum for 10min at room temperature, then add 13mL of 0.1mol / L ferric chloride solution dropwise and continue stirring for 50min. After the reaction is complete, quickly wash with ethanol and dry under vacuum at 50℃ for 6h to obtain Fe. 3+ Complexes modify porous carriers loaded with crosslinking agents;

[0080] (5) Dissolve 1.3g of 1,9-decadiene in 25mL of n-hexane, and add 3g of Fe. 3+ The porous support loaded with the crosslinking agent was modified with the complex, and then impregnated under vacuum at 0.08 MPa for 13 min at room temperature. After restoring to normal pressure, the mixture was stirred for 30 min, rotary evaporated, and finally vacuum dried at 40 °C for 4 h to obtain the crosslinking agent.

[0081] Performance testing

[0082] Tensile properties: The test was conducted using an electronic universal testing machine. The dumbbell-shaped specimens were subjected to a tensile speed of 500 mm / min. Each group of samples was tested 5 times during the test, and the average value was taken as the final result.

[0083] Compression set test: According to GB / T 7759.1-2015, rubber sheets were cut into standard compression test specimens (thickness 10±0.2mm, diameter 29±0.5mm), compressed to 25% of their original thickness in a pressure fixture, and then heated in an oven at 70±1℃ for 24h. After removing the samples, they were allowed to recover at room temperature for 30min, and the percentage of compression set was measured and calculated.

[0084] Friction and wear performance test: According to GB / T 5478-2008, a roller abrasion tester was used to test the abrasion of the rubber samples, and the volume loss of wear (mm) was recorded. 3 The test parameters were set as follows: rotation speed 40 r / min, loading force 10 N, and test time 15 min.

[0085] Dynamic fatigue performance test: According to GB / T 1687-1993, the rubber specimens were subjected to high frequency (2Hz) and low amplitude (15% compression deformation) cyclic loading test using a dynamic fatigue testing machine for a duration of 100,000 cycles. After the test, the specimens were observed for cracks, delamination or fracture, and the fatigue life was recorded. The results of the above performance tests are shown in Table 1.

[0086] Table 1 Performance Test Results

[0087] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Tensile strength (MPa) 28.3 28.5 28.0 26.7 24.8 25.3 22.1 Compression set (%) 12.3 12.3 12.6 15.2 16.8 20.5 18.7 <![CDATA[Wear volume loss (mm 3 )]] 8.8 8.6 9.0 9.3 11.8 10.2 12.5 Physical fatigue life (100,000 cycles) No cracks or delamination No cracks or delamination No cracks or delamination No cracks or delamination Microcracks, no delamination No cracks or delamination Microcracks, no delamination

[0088] Data Analysis: As can be seen from the data in the examples in the table, the rubber exhibits excellent comprehensive performance in many key performance indicators. This is mainly due to the relatively uniform distribution of the prepared crosslinking agent in the rubber matrix, resulting in a uniform distribution of crosslinking sites and the formation of a uniform and tough crosslinking network structure. This makes the connection between rubber molecular chains more stable, effectively transferring and dispersing stress, thereby improving the material's ability to resist external damage. At the same time, the chemical modification and encapsulation treatment on its surface can further regulate the rate and degree of crosslinking reaction, thereby achieving an improvement in the overall performance of the rubber.

[0089] The performance data comparison between Example 2 and Comparative Example 1 in Table 1 shows that alkenylation modification plays a key role in the functionalization effect of the porous support. This indicates that alkenylation, through the co-condensation of vinyltriethoxysilane with the surface of the porous support, makes its inner pore walls rich in vinyl characteristics, which is beneficial to the subsequent adsorption and retention of divinylbenzene. This significantly improves the interfacial bonding effect between divinylbenzene and the porous support, as well as the loading capacity and loading stability of divinylbenzene. This avoids the early leakage phenomenon of divinylbenzene during subsequent temperature crosslinking, resulting in more concentrated network replenishment and a better crosslinking effect.

[0090] As can be seen from the performance data comparison between Example 2 and Comparative Example 2 in Table 1, the Fe³⁺-tannic acid complexation local encapsulation treatment effectively improved the efficiency of the crosslinking agent in the rubber matrix. The metal-phenolic network structure formed by Fe³⁺ and tannic acid constructed a stable coating layer on the surface of the porous carrier. This coating layer not only protects the internally loaded crosslinking components from premature reaction or migration loss during the mixing process, but more importantly, it is stable at room temperature / moderate temperature, and gradually relaxes or cracks under ≥150℃ / strong shear conditions. It can act as an "inner high-threshold gate" to delay the release of divinylbenzene in the core, thereby achieving controllable release at the vulcanization temperature and ensuring that the crosslinking reaction proceeds at an appropriate stage. At the same time, the Fe³⁺-tannic acid complexation local encapsulation can form a synergistic effect with the subsequent paraffin outer layer sealing, thereby achieving rapid softening of the outer low-melting paraffin with temperature and the inner TA-Fe 3+ The complex coordination network requires a two-layer release through high-temperature / strong shear dissociation, forming a two-step release mechanism. This intelligent encapsulation mechanism based on coordination enables the directional delivery and precise release of the crosslinking agent, avoiding the loss and uneven distribution problems of traditional crosslinking agents during processing. This significantly improves crosslinking efficiency and the uniformity of the crosslinking network, and reduces local stress concentration.

[0091] As can be seen from the performance data comparison between Example 2 and Comparative Example 3 in Table 1, further modification with 1,9-decadiene significantly contributes to the performance improvement of the crosslinking agent. First, the long-chain alkyl group and terminal double bond in the 1,9-decadiene molecular structure enable it to interact with both the porous carrier and rubber molecules simultaneously. The long-chain alkyl group enhances interfacial compatibility through physical entanglement, while the double bond participates in the crosslinking reaction during vulcanization. This dual-action mechanism not only enhances the dispersibility of the filler but also further reduces surface migration, effectively improving the stress transfer efficiency from the rigid filler to the flexible matrix. Second, it forms an inner and outer double-layer load with the divinylbenzene loaded in the inner layer of the porous carrier. During subsequent vulcanization and crosslinking, the surface 1,9-decadiene, as a small molecule, participates in plasticization and improves compatibility, while the divinylbenzene, as a large molecule, participates in the later vulcanization and crosslinking. This is an important reason why Example 2 obtained higher tensile strength and better fatigue resistance.

[0092] As can be seen from the performance data comparison of Example 2 and Comparative Example 4 in Table 1, the low-melting-point paraffin encapsulation treatment plays a key role in the processing stability and functional retention of the crosslinking agent. First, as an encapsulation layer, it can isolate the active components of the crosslinking agent from premature contact with the rubber matrix, preventing pre-crosslinking or component migration at the mixing temperature. Second, the outer paraffin layer softens completely at 90-100℃, thereby allowing the shell layer decanadiene to be preferentially released and consumed by the vulcanization system in a timely manner. During the subsequent continued temperature rise and vulcanization process, it forms a temperature-sensitive double-layer release mechanism by complexing with Fe³⁺-tannic acid and locally encapsulating it, thereby ensuring that the crosslinking agent can be continuously and uniformly released throughout the entire vulcanization and crosslinking process.

[0093] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A method for preparing a crosslinking agent, characterized in that, Includes the following steps: S1 Preparation of porous support: Hydrochloric acid and Pluronic P123 were mixed, followed by the addition of tetraethyl orthosilicate and stirring. Then 1,3,5-trimethylbenzene and tetraethyl orthosilicate were added, the temperature was raised to 60℃ and kept at that temperature, then transferred to 90-100℃ for aging for 20-24 hours, purified, and calcined to obtain the porous support. S2 Preparation of alkenylated porous support: Mix porous support, anhydrous toluene, vinyltriethoxysilane and triethylamine, reflux for 3 h, purify to obtain alkenylated porous support; S3 Preparation of porous support loaded with crosslinking agent: Divinylbenzene, n-hexane and alkenylated porous support are mixed, and the mixture is immersed in vacuum at room temperature to 0.08 MPa for 30-60 min, stirred at normal pressure, rotary evaporated and dried to obtain porous support loaded with crosslinking agent; S4 Preparation of Fe 3+ Complex-modified porous support loaded with cross-linking agent: tannic acid, ethanol, deionized water, porous support loaded with cross-linking agent were mixed, vacuumed to 0.06-0.08 MPa at room temperature and stirred, then iron chloride solution was added dropwise, stirred, purified, and Fe 3+ Complex-modified porous support loaded with cross-linking agent; S5 Preparation of Functionalized Porous Supports: 1,9-decadiene, n-hexane, Fe... 3+ The porous carrier modified with the complex and loaded with the crosslinking agent was mixed, and then impregnated at room temperature under vacuum of 0.08 MPa for 10-15 min, stirred at normal pressure, rotary evaporated, and dried to obtain the functionalized porous carrier. S6 Preparation of crosslinking agent: Dissolve low-melting-point paraffin in white oil, add functionalized porous carrier, stir, and dry to obtain crosslinking agent.

2. The preparation method according to claim 1, characterized in that, The ratio of hydrochloric acid, Pluronic P123, tetraethyl orthosilicate, and 1,3,5-trimethylbenzene used in step S1 is 180-220 mL: 3.5-4.5 g: 10-12 g: 1.5-2.5 g.

3. The preparation method according to claim 1, characterized in that, In step S2, the ratio of porous support, anhydrous toluene, vinyltriethoxysilane, and triethylamine is 4-6g:80-100mL:0.6-1g:0.08-0.1g.

4. The preparation method according to claim 1, characterized in that, In step S3, the ratio of divinylbenzene, n-hexane, and alkenylated porous support is 2.2-2.5g: 30-35mL: 2.5-3.5g.

5. The preparation method according to claim 1, characterized in that, In step S4, the ratio of tannic acid, ethanol, deionized water, porous carrier loaded with crosslinking agent, and ferric chloride solution is 0.4-0.6g:25-30mL:25-30mL:2.5-3.5g:10-15mL.

6. The preparation method according to claim 1, characterized in that, The 1,9-decadiene, n-hexane, and Fe mentioned in step S5 3 + The ratio of the amount of complex-modified porous carrier loaded with crosslinking agent is 1-1.5g: 20-30mL: 2.5-3.5g.

7. The preparation method according to claim 1, characterized in that, The ratio of low-melting-point paraffin, white oil, and functionalized porous carrier used in step S6 is 0.8-1g: 20-25mL: 2.5-3.5g.

8. A crosslinking agent, characterized in that, It is prepared according to any one of claims 1-7.

9. An application of the crosslinking agent according to claim 8, characterized in that, Applications in rubber preparation.