Cross-linking agent, preparation method thereof and application of cross-linking agent in rubber preparation

Abstract

The invention relates to the technical field of preparation of cross-linking agents for rubber, in particular to a cross-linking agent, a preparation method of the cross-linking agent and application of the cross-linking agent in rubber preparation. The cross-linking agent is prepared through multi-stage structural design and functional modification and comprises the following steps: firstly, synthesizing a porous carrier by a template method, loading a divinyl benzene cross-linking agent after vinyl silane alkenylation modification, forming inner-layer packaging through Fe < 3 + >-tannic acid coordination, and performing surface functional modification by adopting 1, 9-decadiene to obtain the cross-linking agent. And finally, performing outer layer physical coating through low-melting-point paraffin. The cross-linking agent has a unique dual-threshold gating release characteristic, the outer paraffin provides physical protection at a mixing temperature, the inner coordination network is controllably dissociated at a vulcanization temperature, and on-demand release of cross-linking active components is realized. When the cross-linking agent is applied to rubber preparation, the uniformity of a cross-linking network can be remarkably improved, the cross-linking efficiency is improved, and the problems that a traditional cross-linking agent is easy to consume in advance, uneven in distribution and the like are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of crosslinking agent for rubber, and particularly relates to a crosslinking agent, a preparation method thereof and application thereof in rubber preparation. BACKGROUND

[0002] As important industrial materials, the mechanical properties, durability and fatigue resistance of rubber products directly determine the service life and application range of the products. Traditional rubber formulations usually rely on conventional fillers such as carbon black and sulfur vulcanization system to build crosslinking network. For example, the rubber for automobile tire disclosed in patent literature CN109320792A is mainly made of 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, 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 easily consumed in advance or unevenly distributed due to high temperature and shearing effect, resulting in defects in the crosslinking network in the final vulcanized product, which shows local crosslinking density that is too high or too low. This unevenness can significantly reduce the tensile strength of the material and become a stress concentration point, accelerating the generation and expansion of fatigue cracks under dynamic load. Second, the release and reaction of conventional vulcanizing agents are difficult to accurately control, often leading to premature or late crosslinking reactions, which cannot form the best match with the movement state of the rubber molecular chain. This not only affects the crosslinking efficiency, but also causes the molecular chain to easily slip and rearrange irreversibly when stressed, resulting in increased compression permanent deformation and poor dimensional stability of the product after long-term use. Third, the interfacial bonding force between the filler and the rubber matrix is often insufficient, and the filler particles are easily detached from the matrix under repeated friction and stress, leading to increased wear and decreased wear resistance. In addition, in order to achieve specific processing process, a large amount of processing aids need to be added, which 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 rubber mixing and release on demand during vulcanization, thereby forming a uniform, strong and stable three-dimensional network structure in the rubber matrix, fundamentally improving the comprehensive performance of rubber products. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a crosslinking agent, a preparation method thereof and application thereof in rubber preparation, in order to solve the problems of uneven crosslinking network, easy premature consumption, weak interfacial bonding and poor dynamic performance in existing rubber crosslinking technology.

[0006] Based on the above purpose, the application provides a preparation method of a crosslinking agent, and the specific preparation steps are as follows: S1: preparing a porous carrier: mixing hydrochloric acid and Pluronic P123, magnetically stirring at 40°C, stirring and dissolving for 30 min, then adding tetraethyl orthosilicate dropwise, continuing to stir for 2 h, then adding 1,3,5-trimethylbenzene and supplementing tetraethyl orthosilicate, increasing the temperature to 60°C and keeping for 2-3 h, then transferring the reaction system to a polytetrafluoroethylene-lined hydrothermal reactor, aging at 90-100°C for 20-24 h, after the reaction is completed, filtering, washing with water until neutral, vacuum drying, calcining, and obtaining the porous carrier; S2: preparing an alkenylized porous carrier: dispersing the porous carrier in anhydrous toluene, adding vinyltriethoxysilane and triethylamine, refluxing at 105-110°C for 3 h, and then centrifuging, filtering, washing, and vacuum drying the obtained product to obtain the alkenylized porous carrier; S3: preparing a porous carrier loaded with a crosslinking agent: dissolving divinylbenzene in n-hexane, adding the alkenylized porous carrier, vacuum infiltrating at room temperature to 0.08 MPa for 30-60 min, then restoring the normal pressure and continuing to stir for 1-2 h, rotary evaporation, and vacuum drying to obtain the porous carrier loaded with the crosslinking agent; S4: preparing Fe 3+ complex modified porous carrier loaded with a crosslinking agent: uniformly mixing tannic acid, ethanol, and deionized water, then adding the porous carrier loaded with the crosslinking agent, vacuum infiltrating at room temperature to 0.06-0.08 MPa for 5-10 min, then adding a ferric chloride solution dropwise, continuing to stir for 30-60 min, after the reaction is completed, rinsing, and vacuum drying to obtain the Fe 3+ complex modified porous carrier loaded with a crosslinking agent; S5: preparing a functionalized porous carrier: dissolving 1,9-decadiene in n-hexane, adding the Fe 3+ complex modified porous carrier loaded with a crosslinking agent, vacuum infiltrating at room temperature to 0.08 MPa for 10-15 min, then restoring the normal pressure and stirring for 30 min, rotary evaporation, and vacuum drying to obtain the functionalized porous carrier; S6: preparing a crosslinking agent: dissolving low-melting paraffin in white oil to form a uniform solution at 50-60°C, adding the functionalized porous carrier, rolling and stirring for 10-15 min, standing at room temperature to volatilize the white oil, and then vacuum drying at 50°C for 4 h to obtain the crosslinking agent.

[0007] Preferably, the amount ratio of the hydrochloric acid, Pluronic P123, tetraethyl orthosilicate, and 1,3,5-trimethylbenzene in step S1 is 180-220 mL:3.5-4.5 g:10-12 g:1.5-2.5 g.

[0008] Preferably, the concentration of the hydrochloric acid in step S1 is 2M.

[0009] Preferably, the temperature of the calcination in step S1 is 550-600℃, and the calcination time is 6h.

[0010] Preferably, the ratio of the porous carrier, anhydrous toluene, vinyltriethoxysilane, and triethylamine in step S2 is 4-6g:80-100mL:0.6-1g:0.08-0.1g.

[0011] Preferably, the ratio of the divinylbenzene, n-hexane, and alkenylized porous carrier in step S3 is 2.2-2.5g:30-35mL:2.5-3.5g.

[0012] Preferably, the ratio of the 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.

[0013] Preferably, the concentration of the ferric chloride solution in step S4 is 0.1mol / L.

[0014] Preferably, the ratio of the 1,9-decadiene, n-hexane, and Fe 3+ Preferably, the ratio of the complex modified porous carrier loaded with crosslinking agent, n-hexane, and 1,9-decadiene in step S5 is 1-1.5g:20-30mL:2.5-3.5g.

[0015] Preferably, the ratio of the low-melting-point paraffin wax, white oil, and functionalized porous carrier in step S6 is 0.8-1g:20-25mL:2.5-3.5g.

[0016] Preferably, the Tm of the low-melting-point paraffin wax in step S6 is 58-62℃.

[0017] Preferably, the application further provides a crosslinking agent.

[0018] Further, the application further provides an application of the crosslinking agent in the preparation of rubber.

[0019] The beneficial effects of the application are as follows: The crosslinking agent of the present application has multi-stage packaging and controllable release characteristics through innovative design, realizes multiple synergistic effects through the core porous carrier structure, the interface chemical modification, the inner layer coordination packaging and the outer layer physical coating, so that the active components of the crosslinking agent are effectively protected during the mixing process, the premature reaction and invalid consumption are avoided, and sufficient and uniform active points are ensured to participate in the construction of three-dimensional network in the vulcanization stage, so that the distribution of the formed crosslinking points is more dense and uniform, the connection strength between molecular chains is greatly improved, the material can more effectively disperse and transfer stress, and excellent tensile strength and tear resistance and high service life are exhibited.

[0020] The crosslinking agent of the present application realizes the step release of "outer layer low threshold gating" and "inner layer high threshold gating" through Fe³⁺-tannic acid complex local packaging on the surface of the porous carrier and subsequent low-melting-point paraffin packaging treatment, avoids the loss and uneven distribution of traditional crosslinking agents in the processing process, ensures that the crosslinking agent can be continuously and uniformly released during the entire vulcanization and crosslinking process, thereby significantly improving the crosslinking efficiency and improving the uniformity of the crosslinking network.

[0021] The crosslinking agent of the present application has more excellent crosslinking effect through the way of anchoring divinylbenzene in the inner layer of the porous carrier and loading 1,9-decadiene in the shell layer, and 1,9-decadiene as a small molecule participates in plasticization to improve compatibility, and divinylbenzene as a macromolecule participates in later vulcanization and crosslinking. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the present application more clear and obvious, the present application is further described in detail below in combination with specific examples.

[0023] Preparation Example 1: A crosslinking agent, the specific preparation steps are as follows: (1) Mix 180 mL of 2M hydrochloric acid and 3.5 g of Pluronic P123, magnetically stir at 40℃, stir and dissolve for 30 min, then add 5 g of tetraethyl orthosilicate, continue to stir for 2 h, then add 1.5 g of 1,3,5-trimethylbenzene, and add 5 g of tetraethyl orthosilicate, heat to 60℃ and keep for 2 h, then transfer the reaction system to a polytetrafluoroethylene-lined hydrothermal reactor, and age at 90℃ for 20 h. After the reaction is completed, filter, wash with water until neutral, and vacuum dry at 60℃ for 12 h, and finally calcine at 550℃ for 6 h to obtain a porous carrier; (2) Disperse 4 g of the porous carrier in 80 mL of anhydrous toluene, add 0.6 g of vinyltriethoxysilane and 0.08 g of triethylamine, and reflux at 105℃ for 3 h. The obtained product is centrifuged, filtered, washed with toluene, and vacuum dried at 60℃ for 12 h to obtain an alkenylated porous carrier; (3) 2.2 g divinylbenzene was dissolved in 30 mL n-hexane, 2.5 g of the porous support loaded with crosslinker was added, vacuum infiltration was carried out at room temperature to 0.08 MPa for 30 min, normal pressure was restored, stirring was continued for 1 h, rotary evaporation was performed, and finally vacuum drying was carried out at 40 °C for 4 h to obtain the porous support loaded with crosslinker; (4) 0.4 g tannic acid, 25 mL ethanol, and 25 mL deionized water were uniformly mixed, then 2.5 g of the porous support loaded with crosslinker was added, vacuum was applied at room temperature to 0.06 MPa for 5 min, then 10 mL of a 0.1 mol / L iron chloride solution was added dropwise, stirring was continued for 30 min, after the reaction was completed, rapid ethanol rinsing was performed, and vacuum drying was carried out at 50 °C for 6 h to obtain Fe 3+ complex modified porous support loaded with crosslinker; (5) 1 g 1,9-decadiene was dissolved in 20 mL n-hexane, 2.5 g of the Fe 3+ complex modified porous support loaded with crosslinker was added, vacuum infiltration was carried out at room temperature to 0.08 MPa for 10 min, normal pressure was restored, stirring was continued for 30 min, rotary evaporation was performed, and finally vacuum drying was carried out at 40 °C for 4 h to obtain the functionalized porous support; (6) 0.8 g low-melting-point paraffin was dissolved in 20 mL white oil, a uniform solution was formed by incubation at 50 °C, 2.5 g of the functionalized porous support was added, rolling / stirring was performed for 10 min, after the white oil was volatilized at room temperature, vacuum drying was carried out at 50 °C for 4 h to obtain the crosslinker.

[0024] Preparation Example 2: A crosslinker, the specific preparation steps are as follows: (1) 200 mL of 2M hydrochloric acid and 4 g of Pluronic P123 were mixed, magnetic stirring was carried out at 40 °C, stirring was carried out for 30 min, then 5.5 g of tetraethyl orthosilicate was added dropwise, stirring was continued for 2 h, then 2 g of 1,3,5-trimethylbenzene was added, 5.5 g of tetraethyl orthosilicate was additionally added, the temperature was increased to 60 °C, incubation was carried out for 3 h, then the reaction system was transferred to a polytetrafluoroethylene-lined hydrothermal reactor, and aging was carried out at 95 °C for 23 h, after the reaction was completed, filtration, water washing to neutral, and vacuum drying at 60 °C for 12 h were carried out, and finally calcination was carried out at 560 °C for 6 h to obtain the porous support; (2) 5 g of the porous support was dispersed in 90 mL of anhydrous toluene, 0.8 g of vinyltriethoxysilane and 0.09 g of triethylamine were added, refluxing was carried out at 105 °C for 3 h, the obtained product was subjected to centrifugal filtration, toluene washing, and vacuum drying at 60 °C for 12 h to obtain the alkenylated porous support; (3) 2.4 g of divinylbenzene was dissolved in 35 mL of n-hexane, 3 g of the alkenylated porous support was added, vacuum infiltration was carried out at room temperature to 0.08 MPa for 50 min, normal pressure was restored, stirring was continued for 2 h, rotary evaporation was performed, and finally vacuum drying was carried out at 40 °C for 4 h to obtain the porous support loaded with crosslinker. (4) 0.5 g tannic acid, 30 mL ethanol, 30 mL deionized water were mixed uniformly, then 3 g of porous support loaded with crosslinking agent was added, vacuumed at room temperature to 0.07 MPa for 10 min, then 13 mL of 0.1 mol / L ferric chloride solution was added dropwise, and stirring was continued for 50 min. After the reaction was completed, it was quickly rinsed with ethanol and vacuum dried at 50°C for 6 h to obtain Fe 3+ complex modified porous support loaded with crosslinking agent; (5) 1.3 g of 1,9-decadiene was dissolved in 25 mL of n-hexane, and 3 g of Fe 3+ complex modified porous support loaded with crosslinking agent was vacuumed at room temperature to 0.08 MPa for 13 min, then atmospheric pressure was restored and stirring was continued for 30 min. Rotary evaporation was performed, and finally vacuum drying was performed at 40°C for 4 h to obtain a functionalized porous support; (6) 0.9 g of low-melting-point paraffin was dissolved in 23 mL of white oil to form a uniform solution at 55°C, 3 g of functionalized porous support was added, and rolling and stirring was performed for 13 min. After the white oil volatilized at room temperature, vacuum drying was performed at 50°C for 4 h to obtain a crosslinking agent.

[0025] Preparation Example 3: A crosslinking agent, the specific preparation steps are as follows: (1) 220 mL of 2M hydrochloric acid and 4.5 g of Pluronic P123 were mixed, and magnetic stirring was performed at 40°C. Stirring was performed for 30 min, then 6 g of tetraethyl orthosilicate was added dropwise, and stirring was continued for 2 h. Then 2.5 g of 1,3,5-trimethylbenzene was added, and 6 g of tetraethyl orthosilicate was added. The temperature was increased to 60°C, and the system was kept at this temperature for 3 h. Then the reaction system was transferred to a polytetrafluoroethylene-lined hydrothermal reactor, and aging was performed at 100°C for 24 h. After the reaction was completed, filtration, water washing to neutral, and vacuum drying at 60°C for 12 h were performed, and finally calcination was performed at 600°C for 6 h to obtain a porous support; (2) 6 g of the porous support was dispersed in 100 mL of anhydrous toluene, 1 g of vinyltriethoxysilane and 0.1 g of triethylamine were added, and refluxing was performed at 110°C for 3 h. The obtained product was subjected to centrifugal filtration, toluene washing, and vacuum drying at 60°C for 12 h to obtain an alkenylated porous support; (3) 2.5 g of divinylbenzene was dissolved in 35 mL of n-hexane, and 3.5 g of the alkenylated porous support was added. Vacuuming was performed at room temperature to 0.08 MPa for 60 min, then atmospheric pressure was restored and stirring was continued for 2 h. Rotary evaporation was performed, and finally vacuum drying was performed at 40°C for 4 h to obtain a porous support loaded with crosslinking agent; (4) 0.6 g tannic acid, 30 mL ethanol, 30 mL deionized water were mixed uniformly, then 3.5 g porous carrier loaded with crosslinking agent was added, vacuumed at room temperature to 0.08 MPa for 10 min, then 15 mL of 0.1 mol / L ferric chloride solution was added dropwise, and stirring was continued for 60 min. After the reaction was completed, it was quickly rinsed with ethanol and vacuum dried at 50°C for 6 h to obtain Fe 3+ complex modified porous carrier loaded with crosslinking agent; (5) 1.5 g 1,9-decadiene was dissolved in 30 mL n-hexane, and 3.5 g Fe 3+ complex modified porous carrier loaded with crosslinking agent, vacuumed at room temperature to 0.08 MPa for 15 min, then returned to normal pressure and stirred for 30 min, rotary evaporated, and finally vacuum dried at 40°C for 4 h to obtain functionalized porous carrier; (6) 1 g low-melting-point paraffin was dissolved in 25 mL white oil to form a uniform solution at 60°C, 3.5 g functionalized porous carrier was added, and rolling / stirring was performed for 15 min. After the white oil was volatilized at room temperature, vacuum drying was performed at 50°C for 4 h to obtain a crosslinking agent.

[0026] Example 1: A rubber preparation method, the crosslinking agent used is obtained in Preparation Example 1, and the specific preparation steps are as follows: 70 parts of SBR, 30 parts of BR, 60 parts of precipitated white carbon black, 6 parts of silane coupling agent TESPT, 5 parts of softening oil, 3 parts of ZnO, 2 parts of stearic acid, and 2 parts of antioxidant were placed in an internal mixer, and mixing was performed at 140°C to obtain a sheet. After standing to room temperature, the obtained rubber compound was re-heated to 70°C, and 8 parts of crosslinking agent, 1.6 parts of sulfur, and 1.2 parts of TBBS were again re-heated and mixed in the internal mixer. The temperature was increased to 95°C and maintained for 2 min, and finally maintained at 170°C for 10 min to obtain rubber.

[0027] Example 2: A rubber preparation method, the crosslinking agent used is obtained in Preparation Example 2, and the specific preparation steps are as follows: 70 parts of SBR, 30 parts of BR, 60 parts of precipitated white carbon black, 6 parts of silane coupling agent TESPT, 5 parts of softening oil, 3 parts of ZnO, 2 parts of stearic acid, and 2 parts of antioxidant were placed in an internal mixer, and mixing was performed at 140°C to obtain a sheet. After standing to room temperature, the obtained rubber compound was re-heated to 70°C, and 8 parts of crosslinking agent, 1.6 parts of sulfur, and 1.2 parts of TBBS were again re-heated and mixed in the internal mixer. The temperature was increased to 95°C and maintained for 2 min, and finally maintained at 170°C for 10 min to obtain rubber.

[0028] Example 3: A rubber preparation method, the crosslinking agent used is obtained in Preparation Example 3, and the specific preparation steps are as follows: Put 70 parts of SBR, 30 parts of BR, 60 parts of precipitated white carbon black, 6 parts of silane coupling agent TESPT, 5 parts of softening oil, 3 parts of ZnO, 2 parts of stearic acid, 2 parts of antioxidant in an internal mixer, and mix at 150°C to obtain a sheet. After standing to room temperature, the obtained rubber compound is reheated to 70°C, and 8 parts of crosslinking agent, 1.6 parts of sulfur, 1.2 parts of TBBS are again mixed in the internal mixer, and then the temperature is raised to 105°C and maintained for 3 min, and finally maintained at 175°C for 12 min to obtain the rubber.

[0029] Comparative Example 1: The difference from Example 2 is that the crosslinking agent used is not subjected to alkenyl treatment, and the specific steps are as follows: (1) Mix 200 mL of 2M hydrochloric acid and 4g of Pluronic P123, and stir at 40°C for 30 min. Then add 5.5g of tetraethyl orthosilicate, continue stirring for 2h, then add 2g of 1,3,5-trimethylbenzene, and add 5.5g of tetraethyl orthosilicate, and then heat to 60°C for 3h. Then transfer the reaction system to a polytetrafluoroethylene-lined hydrothermal reactor, and age at 95°C for 23h. After the reaction is completed, filter, wash to neutral, and vacuum dry at 60°C for 12h. Finally, calcine at 560°C for 6h to obtain a porous carrier; (2) Dissolve 2.4g of divinylbenzene in 35mL of n-hexane, add 3g of the porous carrier, and vacuum soak at room temperature to 0.08MPa for 50min, then restore normal pressure and continue stirring for 2h, rotary evaporation, and finally vacuum dry at 40°C for 4h to obtain a porous carrier loaded with crosslinking agent; (3) Mix 0.5g of tannic acid, 30mL of ethanol, and 30mL of deionized water, then add 3g of the porous carrier loaded with crosslinking agent, vacuum stir at room temperature to 0.07MPa for 10min, then add 13mL of 0.1mol / L iron chloride solution dropwise, continue stirring for 50min, then rinse quickly with ethanol, and vacuum dry at 50°C for 6h to obtain a Fe 3+ complex-modified porous carrier loaded with crosslinking agent; (4) Dissolve 1.3g of 1,9-decadiene in 25mL of n-hexane, add 3g of the Fe 3+ complex-modified porous carrier loaded with crosslinking agent, vacuum soak at room temperature to 0.08MPa for 13min, then restore normal pressure and stir for 30min, rotary evaporation, and finally vacuum dry at 40°C for 4h to obtain a functionalized porous carrier; (5) Dissolve 0.9g of low-melting-point paraffin in 23mL of white oil to form a uniform solution at 55°C, add 3g of the functionalized porous carrier, roll coat / stir for 13min, and then let stand at room temperature to volatilize the white oil, and then vacuum dry at 50°C for 4h to obtain a crosslinking agent.

[0030] Comparative Example 2: The difference from Example 2 is that the crosslinking agent is not modified with Fe 3+ Complex modification, the specific steps are as follows: (1) 200 mL of 2M hydrochloric acid and 4 g of Pluronic P123 were mixed, magnetically stirred at 40°C, stirred and dissolved for 30 min, then 5.5 g of tetraethyl orthosilicate was added dropwise, and stirring was continued for 2 h, then 2 g of 1,3,5-trimethylbenzene was added, and 5.5 g of tetraethyl orthosilicate was added, the temperature was raised to 60°C and kept for 3 h, then the reaction system was transferred to a polytetrafluoroethylene lined hydrothermal reactor, and aged at 95°C for 23 h. After the reaction was completed, it was filtered, washed with water to neutral, and vacuum dried at 60°C for 12 h, and finally calcined at 560°C for 6 h to obtain a porous carrier; (2) 5 g of the porous carrier was dispersed in 90 mL of anhydrous toluene, 0.8 g of vinyltriethoxysilane and 0.09 g of triethylamine were added, and refluxed at 105°C for 3 h. The product was centrifuged, filtered, washed with toluene, and vacuum dried at 60°C for 12 h to obtain an alkenylated porous carrier; (3) 2.4 g of divinylbenzene was dissolved in 35 mL of n-hexane, 3 g of the alkenylated porous carrier was added, vacuumed to 0.08 MPa at room temperature for 50 min, then returned to normal pressure and continued to stir for 2 h, rotary evaporated, and finally vacuum dried at 40°C for 4 h to obtain a porous carrier loaded with a crosslinking agent; (4) 1.3 g of 1,9-decadiene was dissolved in 25 mL of n-hexane, 3 g of the porous carrier loaded with the crosslinking agent was added, vacuumed to 0.08 MPa at room temperature for 13 min, then returned to normal pressure and stirred for 30 min, rotary evaporated, and finally vacuum dried at 40°C for 4 h to obtain a functionalized porous carrier; (5) 0.9 g of low-melting-point paraffin was dissolved in 23 mL of white oil to form a uniform solution at 55°C, 3 g of the functionalized porous carrier was added, and rolled and stirred for 13 min. After the white oil was volatilized at room temperature, vacuum drying was carried out at 50°C for 4 h to obtain a crosslinking agent.

[0031] Comparative Example 3: The difference from Example 2 is that the crosslinking agent is not modified with 1,9-decadiene, and the specific steps are as follows: (1) 200 mL of 2M hydrochloric acid and 4 g of Pluronic P123 were mixed, magnetically stirred at 40°C, stirred and dissolved for 30 min, then 5.5 g of tetraethyl orthosilicate was added dropwise, and stirring was continued for 2 h, then 2 g of 1,3,5-trimethylbenzene was added, and 5.5 g of tetraethyl orthosilicate was added, the temperature was raised to 60°C and kept for 3 h, then the reaction system was transferred to a polytetrafluoroethylene lined hydrothermal reactor, and aged at 95°C for 23 h. After the reaction was completed, it was filtered, washed with water to neutral, and vacuum dried at 60°C for 12 h, and finally calcined at 560°C for 6 h to obtain a porous carrier; (2) 5 g of the porous support was dispersed in 90 mL of anhydrous toluene, 0.8 g of vinyltriethoxysilane and 0.09 g of triethylamine were added, and the mixture was refluxed at 105 °C for 3 h. The obtained product was centrifuged, filtered, washed with toluene, and dried at 60 °C under vacuum for 12 h to obtain an alkenylated porous support; (3) 2.4 g of divinylbenzene was dissolved in 35 mL of n-hexane, 3 g of the alkenylated porous support was added, and the mixture was vacuumed at room temperature to 0.08 MPa for 50 min, then returned to normal pressure and stirred for 2 h. After rotary evaporation, the mixture was finally dried at 40 °C under vacuum for 4 h to obtain a porous support loaded with a crosslinking agent; (4) 0.5 g of tannic acid, 30 mL of ethanol, and 30 mL of deionized water were mixed uniformly, then 3 g of the porous support loaded with the crosslinking agent was added, and the mixture was stirred at room temperature under vacuum at 0.07 MPa for 10 min. Then 13 mL of a 0.1 mol / L ferric chloride solution was added dropwise, and the mixture was continuously stirred for 50 min. After the reaction was completed, the mixture was quickly washed with ethanol, and dried at 50 °C under vacuum for 6 h to obtain a Fe 3+ complex modified porous support loaded with a crosslinking agent; (5) 0.9 g of low-melting-point paraffin was dissolved in 23 mL of white oil to form a uniform solution at 55 °C, and 3 g of the Fe 3+ complex modified porous support loaded with a crosslinking agent was added, and the mixture was rolled and stirred for 13 min. After the white oil volatilized at room temperature, the mixture was dried at 50 °C under vacuum for 4 h to obtain a crosslinking agent.

[0032] Comparative Example 4: The difference from Example 2 is that the crosslinking agent is not coated with paraffin, and the specific steps are as follows: (1) 200 mL of 2M hydrochloric acid and 4 g of Pluronic P123 were mixed and stirred at 40 °C. After stirring for 30 min, 5.5 g of tetraethyl orthosilicate was added dropwise, and the mixture was continuously stirred for 2 h. Then 2 g of 1,3,5-trimethylbenzene was added, and 5.5 g of tetraethyl orthosilicate was added. The temperature was increased to 60 °C, and the mixture was kept at this temperature for 3 h. Then the reaction system was transferred to a polytetrafluoroethylene-lined hydrothermal reactor, and the mixture was aged at 95 °C for 23 h. After the reaction was completed, the mixture was filtered, washed with water until neutral, and dried at 60 °C under vacuum for 12 h. Finally, the mixture was calcined at 560 °C for 6 h to obtain a porous support; (2) 5 g of the porous support was dispersed in 90 mL of anhydrous toluene, 0.8 g of vinyltriethoxysilane and 0.09 g of triethylamine were added, and the mixture was refluxed at 105 °C for 3 h. The obtained product was centrifuged, filtered, washed with toluene, and dried at 60 °C under vacuum for 12 h to obtain an alkenylated porous support; (3) 2.4 g of divinylbenzene was dissolved in 35 mL of n-hexane, 3 g of the porous support loaded with the crosslinking agent was added, vacuum infiltration was carried out at room temperature to 0.08 MPa for 50 min, normal pressure was restored, and stirring was continued for 2 h, rotary evaporation was performed, and finally vacuum drying was carried out at 40 °C for 4 h to obtain the porous support loaded with the crosslinking agent; (4) 0.5 g of tannic acid, 30 mL of ethanol, and 30 mL of deionized water were uniformly mixed, then 3 g of the porous support loaded with the crosslinking agent was added, vacuum stirring was carried out at room temperature to 0.07 MPa for 10 min, then 13 mL of a 0.1 mol / L iron chloride solution was added dropwise, stirring was continued for 50 min, after the reaction was completed, rapid ethanol rinsing was performed, and vacuum drying was carried out at 50 °C for 6 h to obtain Fe 3+ complex modified porous support loaded with the crosslinking agent; (5) 1.3 g of 1,9-decadiene was dissolved in 25 mL of n-hexane, 3 g of the Fe 3+ complex modified porous support loaded with the crosslinking agent was added, vacuum infiltration was carried out at room temperature to 0.08 MPa for 13 min, normal pressure was restored, and stirring was continued for 30 min, rotary evaporation was performed, and finally vacuum drying was carried out at 40 °C for 4 h to obtain the crosslinking agent.

[0033] Performance test Tensile property: an electronic universal material testing machine was used for testing, dumbbell-shaped samples were tested at a tensile speed of 500 mm / min, during the testing process, each group of samples was tested 5 times, and the average value was taken as the final result; Compression set test: according to GB / T 7759.1-2015, the rubber sheet was cut into a standard compression sample (thickness 10±0.2 mm, diameter 29±0.5 mm), and was compressed to 25% of the original thickness in a pressure clamp, and then was placed in a 70±1 °C oven for heating for 24 h. After the sample was taken out, it was restored at room temperature for 30 min, and the compression set percentage was measured and calculated; Friction and wear property test: according to GB / T 5478-2008, a drum abrasion tester was used to test the abrasion of the rubber sample, and the wear volume loss (mm 3 ) was recorded, and the test parameters were set as follows: rotation speed 40 r / min, load 10 N, and test time 15 min; Dynamic fatigue property test: according to GB / T 1687-1993, a dynamic fatigue tester was used to test the high frequency (2 Hz) and low amplitude (compression deformation 15%) cyclic loading of the rubber sample, and the duration was 1 million times. After the test was completed, whether cracks, delamination or rupture occurred in the sample was observed, and the fatigue life was recorded. The performance test results are shown in Table 1.

[0034] Table 1 Performance test results 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 Wear volume loss (mm 3 ) 8.8 8.6 9.0 9.3 11.8 10.2 12.5 Endurance life (100,000 cycles) No cracks, delamination No cracks, delamination No cracks, delamination No cracks, delamination Micro cracks, no delamination No cracks, delamination Micro cracks, no delamination Data analysis: From the data of the examples in the table, it can be seen that the rubber shows excellent comprehensive performance in many key performance indicators, which is mainly due to the uniform distribution of the prepared crosslinking agent in the rubber matrix, which makes the crosslinking site uniform, forms a uniform and strong crosslinking network structure, makes the connection between rubber molecular chains more stable, can effectively transfer and disperse stress, thereby improving the ability of the material to resist external damage, at the same time, the chemical modification and encapsulation treatment of the surface can further adjust the rate and degree of crosslinking reaction, thereby realizing the improvement of the comprehensive performance of the rubber.

[0035] From the performance data comparison of Example 2 and Comparative Example 1 in Table 1, it can be seen that the functionalization effect of the alkenylation modification treatment on the porous carrier plays a key role, indicating that the alkenylation treatment co-condenses with the ethenyl triethoxysilane on the surface of the porous carrier, making the inner pore wall rich in vinyl group characteristics, which is conducive to the subsequent adsorption and residence of divinylbenzene, thereby significantly improving the interfacial bonding effect between divinylbenzene and the porous carrier, the loading capacity and stability of divinylbenzene, thereby avoiding the early exosmosis phenomenon of divinylbenzene during subsequent temperature crosslinking, and the late network supplement is more concentrated, and the crosslinking effect is more excellent.

[0036] From the performance data comparison of Example 2 and Comparative Example 2 in Table 1, it can be seen that the Fe³⁺-tannic acid complex local encapsulation treatment effectively improves the action efficiency of the crosslinking agent in the rubber matrix, and the metal-phenolic network structure formed by Fe³⁺ and tannic acid constructs a stable coating layer on the surface of the porous carrier. The coating layer not only protects the internal loaded crosslinking components from premature reaction or migration loss during mixing, but more importantly, it is stable at room temperature / medium temperature, and gradually relaxes or cracks at ≥150°C / strong shear conditions, which can act as an "inner high threshold gate" to delay the release of divinylbenzene in the core, thereby realizing the controllable release at the vulcanizable temperature, ensuring that the crosslinking reaction is carried out at the appropriate stage; at the same time, the Fe³⁺-tannic acid complex local encapsulation can form a mutual synergistic effect with the subsequent paraffin outer sealing, so that the outer low-melting paraffin softens quickly with temperature, and the inner TA-Fe 3+ The complex coordination network needs to be dissociated at high temperature / strong shear, forming a double-layer release with double steps. This intelligent encapsulation mechanism based on coordination effect realizes the directional delivery and precise release of the crosslinking agent, avoiding the loss and uneven distribution of traditional crosslinking agents during processing, thereby significantly improving the crosslinking efficiency and improving the uniformity of the crosslinking network, reducing the local stress concentration phenomenon.

[0037] As can be seen from the performance data comparison of Example 2 and Comparative Example 3 in Table 1, the further modification with 1,9-decadiene makes a significant contribution to the performance improvement of the crosslinking agent; first, the long-chain alkyl and terminal double bond contained in the molecular structure of 1,9-decadiene enable it to simultaneously interact with the porous carrier and rubber molecules, the long-chain alkyl enhances the interfacial compatibility through physical entanglement, and the double bond participates in the crosslinking reaction during vulcanization, this dual action mechanism not only enhances the dispersion of the filler, but also further reduces the surface layer migration, effectively improving the stress transfer efficiency from the rigid filler to the flexible matrix, secondly, it forms an inner and outer double-layer loading with the divinylbenzene loaded in the inner layer of the porous carrier, during subsequent vulcanization and crosslinking, the surface 1,9-decadiene participates in plasticization as a small molecule to improve compatibility, while the divinylbenzene as a macromolecule participates in the later vulcanization and crosslinking, which is an important reason for Example 2 to obtain higher tensile strength and better fatigue resistance.

[0038] 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 function 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; secondly, the outer layer of paraffin completely softens at 90-100°C, so that the shell layer of decadiene is preferentially released and consumed by the vulcanization system in time, and in the subsequent continuous vulcanization process, the Fe³⁺-tannic acid complex locally encapsulated forms a temperature-sensitive double-layer release mechanism, thereby ensuring that the crosslinking agent can be continuously and uniformly released throughout the vulcanization and crosslinking process.

[0039] It should be understood by those of ordinary skill in the art that the above discussion of any of the embodiments is merely exemplary and is not intended to suggest that the scope of the present application is limited to these examples; under the idea of the present application, 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 present application as described above. In order to be brief, they are not provided in detail.

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 modification of porous supports loaded with crosslinking agents: Tannic acid, ethanol, deionized water, and porous supports loaded with crosslinking agents were mixed, and the mixture was stirred under vacuum at room temperature to 0.06-0.08 MPa. Ferric chloride solution was then added dropwise, stirred, and purified to obtain Fe. 3+ Complexes modify porous carriers loaded with crosslinking agents; 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.