A white carbon black reinforced mix and a method of making the same

Abstract

The present application relates to the technical field of silicone rubber material, and particularly relates to a white carbon black reinforced rubber mixture and a preparation method thereof. The present application mixes methyl vinyl silicone rubber, flame-retardant white carbon black, composite flame-retardant white carbon black, hydrogen-containing silicone oil, hydroxyl silicone oil, methoxyl silicone oil, a release agent, a defroster and zinc stearate, and then carries out vacuum mixing after high-temperature mixing to obtain the rubber mixture. The silicone rubber obtained after the vulcanization process of the rubber mixture has excellent flame-retardant performance and mechanical properties, and therefore has a wide application prospect in the technical field of silicone rubber material.

Description

Technical Field

[0001] This invention relates to the field of silicone rubber materials technology, specifically a silica-reinforced compound and its preparation method. Background Technology

[0002] Silicone rubber is a polymeric elastic material based on the main chain structure of organopolysiloxanes and reinforced with fillers. Due to its unique thermal stability, reliable electrical insulation properties, and good biocompatibility, this material system has become an indispensable key material in industries such as aerospace, electronics, transportation, and biomedicine.

[0003] However, despite the aforementioned comprehensive advantages of silicone rubber compounds, they still have significant limitations in the following aspects, restricting their application in more demanding scenarios: First, silicone rubber has insufficient flame retardant properties. Although silicone rubber itself has certain flame retardant properties, it will still burn when exposed to open flames or sustained high temperatures without the addition of external flame retardants, and will form a brittle silicate ash layer after burning, allowing the flame to continue to spread. Second, silicone rubber has inherent shortcomings in mechanical properties. On the one hand, traditional additive flame retardants, such as aluminum hydroxide and magnesium hydroxide, can improve flame retardancy, but often require high filler amounts, which will seriously damage the mechanical properties and processing flowability of silicone rubber materials. On the other hand, the intermolecular forces of silicone rubber are weak. Although nanofillers such as silica can be added for reinforcement, the actual reinforcement effect is highly dependent on the dispersion state of the silica filler in the matrix. When the silica filler is not sufficiently dispersed in the matrix, it is very easy to agglomerate during the mixing process due to hydrogen bonding, leading to a deterioration of mechanical properties.

[0004] To overcome the shortcomings of the prior art, the present invention provides a silica-reinforced compound and its preparation method. Summary of the Invention

[0005] The purpose of this invention is to provide a silica-reinforced compound and its preparation method to solve the problems raised in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a silica-reinforced compound includes the following steps: mixing methyl vinyl silicone rubber, flame-retardant silica, composite flame-retardant silica, hydrogen-containing silicone oil, hydroxyl silicone oil, methoxyl silicone oil, release agent, defrosting agent, and zinc stearate, followed by high-temperature mixing and then vacuum mixing to obtain the compound. Flame-retardant silica is obtained by further grafting 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide onto the surface of silica after organosilicon modification; composite flame-retardant silica is obtained by further grafting amino-modified phosphaphenanthrene material onto the surface of silica after organosilicon modification.

[0007] Ideally, the high-temperature mixing temperature is 155-165℃ and the time is 3-5 hours; the vacuum mixing temperature is 120-130℃ and the time is 1.0-1.5 hours.

[0008] In a more optimized manner, the content of each component in the compound is as follows (by mass): 85-110 parts methyl vinyl silicone rubber, 20-30 parts flame retardant silica, 30-40 parts composite flame retardant silica, 2-3 parts hydrogen-containing silicone oil, 6-10 parts hydroxyl silicone oil, 1-3 parts methoxy silicone oil, 0.2-0.6 parts release agent, 1-2 parts defrosting agent, and 0.05-0.08 parts zinc stearate.

[0009] A more optimized preparation process for flame-retardant silica is as follows: Step 1: Mix silica, anhydrous toluene, and deionized water, and stir under sealed conditions at 25-30℃ for 10-12 minutes. After stirring, add tetramethyldivinyldisilazane dropwise. Continue stirring for 2.0-2.5 hours after the addition is complete. Then, reflux at 105-110℃ for 5.5-6.5 hours. After the reaction is complete, wash, filter, and dry to obtain modified silica. Step 2: Mix modified silica and tetrahydrofuran, and ultrasonically disperse them evenly to obtain a modified silica dispersion; then mix 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and tetrahydrofuran, and add the modified silica dispersion at 8-10℃. After the addition is complete, raise the temperature to 60-65℃ and stir for 3.5-4.5h. After the reaction is complete, evaporate by rotary evaporation and dry to obtain flame-retardant silica.

[0010] In a more optimized manner, in step 1, the mass-to-volume ratio of silica, anhydrous toluene, deionized water, and tetramethyldivinyldisilazane is 5 g: 200 mL: 0.5 mL: (1.7-1.9) g.

[0011] In a more optimized manner, in step 2, the reaction mass ratio of modified silica and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 7:(2.5-3.0).

[0012] A more optimized preparation process for composite flame-retardant silica is as follows: Step S1: Under nitrogen atmosphere, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 4-aminoacetophenone, aniline, and p-toluenesulfonic acid are mixed and stirred at 130-140℃ for 15-20 h. After the reaction is completed, the mixture is precipitated, filtered, washed, and dried to obtain the amino-modified phosphaphenanthrene material. Step S2: Mix precipitated silica and mixed solvent, and ultrasonically disperse to obtain precipitated silica dispersion; mix γ-glycidyl etheroxypropyltrimethoxysilane and mixed solvent, and stir to obtain coupling agent solution; heat precipitated silica dispersion to 70-75℃, and then add coupling agent solution dropwise. After the addition is complete, continue the reaction for 13-15 hours. After the reaction is complete, cool, filter, and dry to obtain epoxidized precipitated silica. Step S3: Mix N,N-dimethylformamide, aminophosphine, epoxidized silica, and triethylamine, and heat to 135-145℃ under nitrogen atmosphere for 7-8 hours. After the reaction is completed, cool, filter, wash, and dry to obtain composite flame-retardant silica.

[0013] In a more optimized manner, in step S1, the mass-to-volume ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 4-aminoacetophenone, aniline, and p-toluenesulfonic acid is 10 g : (5-6) g : 17 mL : 0.32 g.

[0014] In a more optimized manner, in step S2, the mixed solvent includes ethanol and deionized water in a volume ratio of (9-10):1; the mass-volume ratio of silica and γ-glycidyl etheroxypropyltrimethoxysilane is 1 g: (1.2-1.4) mL; in step S3, the mass-volume ratio of N,N-dimethylformamide, aminophosphine, epoxidized silica, and triethylamine is 150 mL: (2.0-2.2) g: 2.5 g: 1.5 mL.

[0015] The beneficial effects of this invention are: The key feature of this invention is that by adding silica, anhydrous toluene, deionized water, and tetramethyldivinyldisilazane, the Si-N bonds undergo hydrolysis and condensation reaction with the silanol groups on the silica surface, forming Si-O-Si covalent bonds. This grafts vinyl-containing organosilicon groups onto the silica surface, resulting in modified silica. The organosilicon layer on the surface of this modified silica effectively shields the native hydrophilic surface of the silica, greatly reducing its extremely high surface energy and interparticle hydrogen bonding, thus effectively improving the dispersion stability of the silica.

[0016] Furthermore, by adding modified silica and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, an addition reaction of pH bonds and carbon-carbon double bonds is carried out to introduce flame-retardant groups, resulting in flame-retardant silica. This step firmly grafts 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide with covalent bonds. During combustion, the bonded DOPO groups can efficiently decompose and release highly reactive free radicals. These free radicals can capture hydrogen free radicals in the combustion chain reaction, thereby quenching the flame and effectively exerting a gas-phase flame-retardant effect. In addition, silica itself is an excellent inert filler and char-forming promoter. During combustion, the silica surface synergistically with the decomposition products of DOPO helps to form a dense and stable char layer on the material surface. This char layer can insulate against heat and oxygen and inhibit the escape of combustible volatile components.

[0017] The invention is characterized by the following steps: Aminated phosphaphenanthrene material is obtained by adding 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 4-aminoacetophenone, aniline, and p-toluenesulfonic acid; then, silica is modified with a coupling agent solution to obtain epoxidized silica. One end of the coupling agent, after hydrolysis of the methoxy group, condenses with the silica surface, while the other end introduces an epoxy group. This modification not only improves the compatibility and dispersibility of silica in complex organic systems but also provides active groups for subsequent grafting of flame-retardant groups. Furthermore, N,N-dimethylformamide, aminated phosphaphenanthrene material, epoxidized silica, and triethylamine are mixed to undergo a ring-opening reaction, yielding a composite flame-retardant silica. The aminated phosphaphenanthrene material includes phosphorus and nitrogen, two highly efficient flame-retardant elements. DOPO itself is also an effective gas-phase free radical scavenger; the two can synergistically promote char formation and gas-phase dilution, thereby achieving highly efficient flame-retardant performance. Therefore, by fixing the aminophosphine material onto the surface of silica via a ring-opening reaction in the form of covalent bonds, the migration, leaching, and precipitation of small molecule flame retardants are avoided, ensuring the durability and high efficiency of the flame retardant effect.

[0018] Finally, methyl vinyl silicone rubber, flame-retardant silica, composite flame-retardant silica, hydrogen-containing silicone oil, hydroxyl silicone oil, methoxyl silicone oil, release agent, defrosting agent, and zinc stearate are mixed, and then vacuum-mixed after high-temperature compounding to obtain a compound. The silicone rubber obtained after subsequent vulcanization exhibits excellent flame-retardant and mechanical properties. Specifically, this formulation abandons traditional high-filler additive flame retardants and instead uses two chemically bonded flame-retardant silicas. The flame-retardant silica introduces DOPO groups through an addition reaction, primarily targeting gas-phase free radical quenching; the composite flame-retardant silica fixes the nitrogen-phosphorus synergistic DOPO derivative through a ring-opening reaction, providing more stable condensed-phase char protection. The two fillers synergistically enhance the flame-retardant properties of the silicone rubber. Furthermore, the two chemically bonded flame-retardant silicaes prepared in this invention exhibit surface modification layers that significantly enhance their compatibility and chemical bonding with the methyl vinyl silicone rubber matrix. During vulcanization, they form a robust filler-polymer network, thereby ensuring the material's mechanical properties. Hydrogen- and hydroxyl-containing silicone oils, acting as structure control agents, further ensure the uniform dispersion of the filler network, avoiding mechanical defects caused by agglomeration. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Raw material source: The following materials are provided: Silica (white carbon black), YX-813 (provided by Fujian Yuanxiang New Material Co., Ltd.); Methoxylated silicone oil, 209 (provided by Xuancheng Sixin New Material Co., Ltd.); Hydroxylated silicone oil, 101 (provided by Xuancheng Sixin New Material Co., Ltd.); Mold release agent, XY-TM01 (provided by Guangzhou Siyou New Material Technology Co., Ltd.); Defrosting agent, XY-CS (provided by Guangzhou Siyou New Material Technology Co., Ltd.); Zinc stearate, SAK-ZS-PLB (provided by Shanghai Yunhe Materials Technology Co., Ltd.); Methyl vinyl silicone rubber, 110-3 vinyl 0.22 wt%, 0.22 wt% vinyl content (provided by Xinjiang Hesheng Silicon Industry New Material Co., Ltd.); Hydrogen-containing silicone oil, 1.6 wt% hydrogen content (provided by Guangzhou Laibao Silicon Materials Co., Ltd.); Part by weight is 1 g.

[0021] Example 1: Step 1: Mix silica, anhydrous toluene, and deionized water, and stir in a sealed container at 30°C for 12 minutes. After stirring, add tetramethyldivinyldisilazane dropwise. Continue stirring for 2.5 hours after the addition is complete, then heat to 110°C and reflux for 6.5 hours. After the reaction is complete, wash, filter, and dry to obtain modified silica. The mass-to-volume ratio of silica, anhydrous toluene, deionized water, and tetramethyldivinyldisilazane is 5 g: 200 mL: 0.5 mL: 1.8 g. Step 2: Mix modified silica and tetrahydrofuran, and ultrasonically disperse to obtain a modified silica dispersion; then mix 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and tetrahydrofuran, and add the modified silica dispersion at 10℃. After the addition is complete, raise the temperature to 65℃ and stir for 4.5h. After the reaction is complete, evaporate by rotary evaporation and dry to obtain flame-retardant silica; the mass ratio of modified silica to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 7:2.7. Step 3: Under nitrogen atmosphere, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 4-aminoacetophenone, aniline, and p-toluenesulfonic acid were mixed and stirred at 140℃ for 20 h. After the reaction was completed, the mixture was precipitated, filtered, washed, and dried to obtain the amino-modified phosphaphenanthrene material. The mass-to-volume ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 4-aminoacetophenone, aniline, and p-toluenesulfonic acid was 10 g: 5.5 g: 17 mL: 0.32 g. Step 4: Mix precipitated silica and a mixed solvent, and ultrasonically disperse until uniform to obtain a precipitated silica dispersion; mix γ-glycidoxypropyltrimethoxysilane and a mixed solvent, and stir until uniform to obtain a coupling agent solution; heat the precipitated silica dispersion to 75°C, and then add the coupling agent solution dropwise. After the addition is complete, continue the reaction for 15 hours. After the reaction is complete, cool, filter, and dry to obtain epoxidized precipitated silica; the mixed solvent includes ethanol and deionized water in a volume ratio of 9:1; the mass-to-volume ratio of precipitated silica to γ-glycidoxypropyltrimethoxysilane is 1 g: 1.3 mL; Step 5: Mix N,N-dimethylformamide, aminophosphonium phenanthrene material, epoxidized silica, and triethylamine, heat to 145℃ under nitrogen atmosphere, and continue the reaction for 8 hours. After the reaction is completed, cool, filter, wash, and dry to obtain composite flame-retardant silica. The mass-to-volume ratio of N,N-dimethylformamide, aminophosphonium phenanthrene material, epoxidized silica, and triethylamine is 150mL:2.1g:2.5g:1.5mL. Step 6: Mix 110g of methyl vinyl silicone rubber, 30g of flame-retardant silica, 40g of composite flame-retardant silica, 2.5g of hydrogen-containing silicone oil, 10g of hydroxyl silicone oil, 3g of methoxy silicone oil, 0.6g of mold release agent, 2g of defrosting agent, and 0.08g of zinc stearate. Knead at 165℃ for 5 hours, then vacuum knead at 130℃ for 1.5 hours to obtain the compound.

[0022] Example 2: Step 1: Mix silica, anhydrous toluene, and deionized water, and stir in a sealed container at 27°C for 11 min. After stirring, add tetramethyldivinyldisilazane dropwise. Continue stirring for 2.2 h after the addition is complete, then heat to 107°C and reflux for 6 h. After the reaction is complete, wash, filter, and dry to obtain modified silica. The mass-to-volume ratio of silica, anhydrous toluene, deionized water, and tetramethyldivinyldisilazane is 5 g: 200 mL: 0.5 mL: 1.8 g. Step 2: Mix modified silica and tetrahydrofuran, and ultrasonically disperse to obtain a modified silica dispersion; then mix 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and tetrahydrofuran, and add the modified silica dispersion at 9℃. After the addition is complete, raise the temperature to 62℃ and stir for 4 hours. After the reaction is complete, rotary evaporate and dry to obtain flame-retardant silica; the mass ratio of modified silica to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 7:2.7. Step 3: Under nitrogen atmosphere, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 4-aminoacetophenone, aniline, and p-toluenesulfonic acid were mixed and stirred at 135℃ for 17 h. After the reaction, the mixture was precipitated, filtered, washed, and dried to obtain the amino-modified phosphaphenanthrene material. The mass-to-volume ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 4-aminoacetophenone, aniline, and p-toluenesulfonic acid was 10 g: 5.5 g: 17 mL: 0.32 g. Step 4: Mix precipitated silica and a mixed solvent, and ultrasonically disperse until uniform to obtain a precipitated silica dispersion; mix γ-glycidoxypropyltrimethoxysilane and a mixed solvent, and stir until uniform to obtain a coupling agent solution; heat the precipitated silica dispersion to 72℃, and then add the coupling agent solution dropwise. After the addition is complete, continue the reaction for 14 hours. After the reaction is complete, cool, filter, and dry to obtain epoxidized precipitated silica; the mixed solvent includes ethanol and deionized water in a volume ratio of 9:1; the mass-to-volume ratio of precipitated silica to γ-glycidoxypropyltrimethoxysilane is 1 g: 1.3 mL; Step 5: Mix N,N-dimethylformamide, aminophosphonium phenanthrene material, epoxidized silica, and triethylamine, heat to 140℃ under nitrogen atmosphere, and continue the reaction for 7.5 hours. After the reaction is completed, cool, filter, wash, and dry to obtain composite flame-retardant silica. The mass-to-volume ratio of N,N-dimethylformamide, aminophosphonium phenanthrene material, epoxidized silica, and triethylamine is 150mL:2.1g:2.5g:1.5mL. Step 6: Mix 110g of methyl vinyl silicone rubber, 30g of flame-retardant silica, 40g of composite flame-retardant silica, 2.5g of hydrogen-containing silicone oil, 10g of hydroxyl silicone oil, 3g of methoxy silicone oil, 0.6g of mold release agent, 2g of defrosting agent, and 0.08g of zinc stearate. Knead at 160℃ for 4 hours, then vacuum knead at 125℃ for 1.2 hours to obtain the compound.

[0023] Example 3: Step 1: Mix silica, anhydrous toluene, and deionized water, and stir in a sealed container at 27°C for 11 min. After stirring, add tetramethyldivinyldisilazane dropwise. Continue stirring for 2.0 h after the addition is complete, then heat to 105°C and reflux for 5.5 h. After the reaction is complete, wash, filter, and dry to obtain modified silica. The mass-to-volume ratio of silica, anhydrous toluene, deionized water, and tetramethyldivinyldisilazane is 5 g: 200 mL: 0.5 mL: 1.8 g. Step 2: Mix modified silica and tetrahydrofuran, and ultrasonically disperse to obtain a modified silica dispersion; then mix 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and tetrahydrofuran, and add the modified silica dispersion at 8°C. After the addition is complete, raise the temperature to 60°C and stir for 3.5 hours. After the reaction is complete, evaporate by rotary evaporation and dry to obtain flame-retardant silica; the mass ratio of modified silica to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 7:2.7. Step 3: Under nitrogen atmosphere, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 4-aminoacetophenone, aniline, and p-toluenesulfonic acid were mixed and stirred at 130℃ for 15 h. After the reaction, the mixture was precipitated, filtered, washed, and dried to obtain the amino-modified phosphaphenanthrene material. The mass-to-volume ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 4-aminoacetophenone, aniline, and p-toluenesulfonic acid was 10 g: 5.5 g: 17 mL: 0.32 g. Step 4: Mix precipitated silica and the mixed solvent, and ultrasonically disperse until uniform to obtain a precipitated silica dispersion; mix γ-glycidoxypropyltrimethoxysilane and the mixed solvent, and stir until uniform to obtain a coupling agent solution; heat the precipitated silica dispersion to 70℃, and then add the coupling agent solution dropwise. After the addition is complete, continue the reaction for 13 hours. After the reaction is complete, cool, filter, and dry to obtain epoxidized precipitated silica; the mixed solvent includes ethanol and deionized water in a volume ratio of 9:1; the mass-to-volume ratio of precipitated silica to γ-glycidoxypropyltrimethoxysilane is 1 g: 1.3 mL; Step 5: Mix N,N-dimethylformamide, aminophosphonium phenanthrene material, epoxidized silica, and triethylamine, heat to 135℃ under nitrogen atmosphere, and continue the reaction for 7 hours. After the reaction is completed, cool, filter, wash, and dry to obtain composite flame-retardant silica. The mass-to-volume ratio of N,N-dimethylformamide, aminophosphonium phenanthrene material, epoxidized silica, and triethylamine is 150mL:2.1g:2.5g:1.5mL. Step 6: Mix 110g of methyl vinyl silicone rubber, 30g of flame-retardant silica, 40g of composite flame-retardant silica, 2.5g of hydrogen-containing silicone oil, 10g of hydroxyl silicone oil, 3g of methoxy silicone oil, 0.6g of mold release agent, 2g of defrosting agent, and 0.08g of zinc stearate. Knead at 155℃ for 3 hours, then vacuum knead at 120℃ for 1 hour to obtain the compound.

[0024] Comparative Example 1: The flame-retardant silica was replaced with ordinary silica material, and the rest was the same as in Example 1. The specific steps are as follows: Step 1: Under nitrogen atmosphere, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 4-aminoacetophenone, aniline, and p-toluenesulfonic acid were mixed and stirred at 140°C for 20 hours. After the reaction was completed, the mixture was precipitated, filtered, washed, and dried to obtain amino-modified phosphaphenanthrene material. The mass-volume ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 4-aminoacetophenone, aniline, and p-toluenesulfonic acid was 10g:5.5g:17mL:0.32g. Step 2: Mix precipitated silica and a mixed solvent, and ultrasonically disperse until uniform to obtain a precipitated silica dispersion; mix γ-glycidoxypropyltrimethoxysilane and a mixed solvent, and stir until uniform to obtain a coupling agent solution; heat the precipitated silica dispersion to 75°C, and then add the coupling agent solution dropwise. After the addition is complete, continue the reaction for 15 hours. After the reaction is complete, cool, filter, and dry to obtain epoxidized precipitated silica; the mixed solvent includes ethanol and deionized water in a volume ratio of 9:1; the mass-to-volume ratio of precipitated silica to γ-glycidoxypropyltrimethoxysilane is 1 g: 1.3 mL; Step 3: N,N-dimethylformamide, aminophosphonium phenanthrene material, epoxidized silica, and triethylamine were mixed and heated to 145°C under nitrogen atmosphere for 8 hours. After the reaction was completed, the mixture was cooled, filtered, washed, and dried to obtain composite flame-retardant silica. The mass-to-volume ratio of N,N-dimethylformamide, aminophosphonium phenanthrene material, epoxidized silica, and triethylamine was 150 mL: 2.1 g: 2.5 g: 1.5 mL. Step 4: Mix 110g methyl vinyl silicone rubber, 30g silica, 40g composite flame retardant silica, 2.5g hydrogen-containing silicone oil, 10g hydroxyl silicone oil, 3g methoxy silicone oil, 0.6g mold release agent, 2g defrosting agent, and 0.08g zinc stearate. Knead at 165℃ for 5 hours, then vacuum knead at 130℃ for 1.5 hours to obtain the compound.

[0025] Comparative Example 2: Flame-retardant silica and composite flame-retardant silica were replaced with ordinary silica materials, and the rest was the same as in Example 1. The specific steps are as follows: 110g of methyl vinyl silicone rubber, 70g of silica, 2.5g of hydrogen-containing silicone oil, 10g of hydroxyl silicone oil, 3g of methoxy silicone oil, 0.6g of release agent, 2g of defrosting agent, and 0.08g of zinc stearate were mixed and kneaded at 165°C for 5 hours, and then vacuum kneaded at 130°C for 1.5 hours to obtain the compound.

[0026] Testing and experimentation: Flame retardant performance test: A vulcanizing agent and a platinum complex were added to the compound obtained after the mixing process of this invention, and the mixture was then vulcanized to obtain a silicone rubber sample. Referring to GB / T 10707-2008 "Determination of Burning Properties of Rubber", the flame retardant performance of the sample was tested using the vertical burning method. The sample size was 130mm × 13mm × 3mm.

[0027] Tensile strength: A vulcanizing agent and a platinum complex were added to the compound obtained after the mixing process of this invention, and the mixture was then vulcanized to obtain a silicone rubber sample. The sample was tested according to GB / T 528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber", using a dumbbell-shaped type 1 sample.

[0028] Tear strength: A vulcanizing agent and a platinum complex were added to the compound obtained after the mixing process of this invention, and the mixture was then vulcanized to obtain silicone rubber samples. The tests were conducted according to GB / T 529-2008 "Determination of Tear Strength of Vulcanized Rubber or Thermoplastic Rubber", using right-angled samples. The results are shown in the table below:

[0029] Conclusion: The experimental data show that the properties of the samples in Examples 1-3 did not fluctuate significantly. In Comparative Example 1, after replacing the flame-retardant silica with ordinary silica, only the composite flame-retardant silica was retained as a flame-retardant enhancement, resulting in a decrease in the flame retardancy of the sample. Simultaneously, the corresponding ordinary silica material had poor dispersibility, which easily damaged the mechanical properties of the sample, leading to a decrease in tensile strength and tear strength. In Comparative Example 2, both the flame-retardant silica and the composite flame-retardant silica were replaced with ordinary silica, resulting in a further decrease in both flame retardancy and mechanical properties compared to Comparative Example 1.

[0030] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process method article or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process method article or apparatus.

[0031] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a silica-reinforced compound, characterized in that: Includes the following steps: Methyl vinyl silicone rubber, flame retardant silica, composite flame retardant silica, hydrogen-containing silicone oil, hydroxyl silicone oil, methoxyl silicone oil, release agent, defrosting agent, and zinc stearate are mixed, and then vacuum-mixed after high-temperature mixing to obtain the compound. Flame-retardant silica is obtained by further grafting 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide onto the surface of silica after organosilicon modification; composite flame-retardant silica is obtained by further grafting amino-modified phosphaphenanthrene material onto the surface of silica after organosilicon modification.

2. The method for preparing a silica-reinforced compound according to claim 1, characterized in that: The high-temperature mixing temperature is 155-165℃, and the time is 3-5 hours; the vacuum mixing temperature is 120-130℃, and the time is 1.0-1.5 hours.

3. The method for preparing a silica-reinforced compound according to claim 1, characterized in that: The content of each component in the compound is as follows (by mass): 85-110 parts methyl vinyl silicone rubber, 20-30 parts flame retardant silica, 30-40 parts composite flame retardant silica, 2-3 parts hydrogen-containing silicone oil, 6-10 parts hydroxyl silicone oil, 1-3 parts methoxy silicone oil, 0.2-0.6 parts release agent, 1-2 parts defrosting agent, and 0.05-0.08 parts zinc stearate.

4. The method for preparing a silica-reinforced compound according to claim 3, characterized in that: The preparation process of flame-retardant silica is as follows: Step 1: Mix silica, anhydrous toluene, and deionized water, and stir under sealed conditions at 25-30℃ for 10-12 minutes. After stirring, add tetramethyldivinyldisilazane dropwise. Continue stirring for 2.0-2.5 hours after the addition is complete. Then, reflux at 105-110℃ for 5.5-6.5 hours. After the reaction is complete, wash, filter, and dry to obtain modified silica. Step 2: Mix modified silica and tetrahydrofuran, and ultrasonically disperse them evenly to obtain a modified silica dispersion; then mix 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and tetrahydrofuran, and add the modified silica dispersion at 8-10℃. After the addition is complete, raise the temperature to 60-65℃ and stir for 3.5-4.5h. After the reaction is complete, evaporate by rotary evaporation and dry to obtain flame-retardant silica.

5. The method for preparing a silica-reinforced compound according to claim 4, characterized in that: In step 1, the mass-to-volume ratio of silica, anhydrous toluene, deionized water, and tetramethyldivinyldisilazane is 5g:200mL:0.5mL:(1.7-1.9)g.

6. The method for preparing a silica-reinforced compound according to claim 4, characterized in that: In step 2, the reaction mass ratio of modified silica and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 7:(2.5-3.0).

7. The method for preparing a silica-reinforced compound according to claim 3, characterized in that: The preparation process of composite flame-retardant silica is as follows: Step S1: Under nitrogen atmosphere, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 4-aminoacetophenone, aniline, and p-toluenesulfonic acid are mixed and stirred at 130-140℃ for 15-20 h. After the reaction is completed, the mixture is precipitated, filtered, washed, and dried to obtain the amino-modified phosphaphenanthrene material. Step S2: Mix precipitated silica and mixed solvent, and ultrasonically disperse to obtain precipitated silica dispersion; mix γ-glycidyl etheroxypropyltrimethoxysilane and mixed solvent, and stir to obtain coupling agent solution; heat precipitated silica dispersion to 70-75℃, and then add coupling agent solution dropwise. After the addition is complete, continue the reaction for 13-15 hours. After the reaction is complete, cool, filter, and dry to obtain epoxidized precipitated silica. Step S3: Mix N,N-dimethylformamide, aminophosphine, epoxidized silica, and triethylamine, and heat to 135-145℃ under nitrogen atmosphere for 7-8 hours. After the reaction is completed, cool, filter, wash, and dry to obtain composite flame-retardant silica.

8. The method for preparing a silica-reinforced compound according to claim 7, characterized in that: In step S1, the mass-to-volume ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 4-aminoacetophenone, aniline, and p-toluenesulfonic acid is 10 g : (5-6) g : 17 mL : 0.32 g.

9. The method for preparing a silica-reinforced compound according to claim 7, characterized in that: In step S2, the mixed solvent includes ethanol and deionized water in a volume ratio of (9-10):1; the mass-volume ratio of silica and γ-glycidyl etheroxypropyltrimethoxysilane is 1g:(1.2-1.4)mL; in step S3, the mass-volume ratio of N,N-dimethylformamide, aminophosphine, epoxidized silica, and triethylamine is 150mL:(2.0-2.2)g:2.5g:1.5mL.

10. A silica-reinforced compound, characterized in that, Prepared by the preparation method according to any one of claims 1-9.

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