Preparation method of silica aerogel modified rubber composite and hose

Abstract

The application relates to the technical field of high polymer materials, and discloses a preparation method of a silica aerogel modified rubber composite material and a hose. Chlorophenyl polysilane and phenolic resin modified silica aerogel are added into silicone rubber to optimize the performance. The silica aerogel is a three-dimensional network skeleton, has high porosity, a high melting point and high temperature stability, keeps stable at high temperature, and maintains high efficient heat insulation effect for a long time; the phenolic resin contains a large number of aromatic rings and hydroxyl groups, is easy to cause dehydration, cross-linking and condensation reaction at high temperature, forms a dense, high-temperature-resistant and not-easy-to-collapse carbon layer, blocks heat transfer and prevents combustible gas diffusion, improves the carbon residue rate and the flame retardance of the material; the silicon-chlorine bond of the chlorophenyl polysilane reacts with the silica and the phenolic resin, so that the two are combined, the formed carbon layer is denser, the thermal shock resistance is stronger, the dispersity of the aerogel is improved, and the mechanical properties and the ablation performance of the silicone rubber are enhanced.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a composite material of silica aerogel modified rubber and a method for preparing a flexible tube. Background Technology

[0002] Silicone rubber has been widely researched and applied as an insulation material both domestically and internationally in recent years. It boasts the widest operating temperature range among general-purpose rubbers, exhibiting characteristics such as low smoke, low residue, and low characteristic signal, along with excellent weather resistance and superior resistance to ablation and erosion. Under oxygen-rich and high-speed airflow, the surface of a silicone rubber-based insulation layer can form a robust and dense hard layer during the burning process, thus preventing further erosion of the deeper insulation layers by high-temperature combustion gases. However, silicone rubber also has some drawbacks, such as poor mechanical properties. Unreinforced silicone rubber has insufficient maximum tensile strength, requiring reinforcement to meet the performance requirements of most applications. Furthermore, its ablation resistance is not high enough, necessitating the addition of ablation-resistant fillers to improve its burning performance.

[0003] Aerogels are typical nanoporous materials widely used in high-temperature insulation, catalyst supports, heavy metal ion adsorption, and solar cells. Silica aerogels are currently the most researched and widely applied type of aerogel material. However, silica aerogels suffer from drawbacks such as high brittleness, low strength, difficulty in controlling infrared optical properties, poor high-temperature resistance, and complex high-temperature phases, posing numerous challenges in practical applications. Combining silica aerogels with materials such as nanofibers, organic polymers, and graphene is an important way to achieve their functionalization.

[0004] Phenolic resin is the world's first synthetic resin to be industrially produced, with a history of over a century. Due to its readily available and inexpensive raw materials, simple production process and equipment, and excellent mechanical properties, heat resistance, dimensional stability, molding and processability, flame retardancy, and low smoke emission, it has become an indispensable material in the industrial sector. Summary of the Invention

[0005] (a) Technical problems to be solved:

[0006] To address the shortcomings of existing technologies, this invention provides a method for preparing a composite material of silica aerogel-modified rubber and a hose, which solves the problems of insufficient flame retardancy and weak mechanical properties of traditional rubber materials.

[0007] (II) Technical Solution: The preparation method of the silica aerogel modified rubber composite material is as follows:

[0008] Step (1): Weigh the silica aerogel and add it to dichloromethane. Sonicate for 40-60 min, add chlorophenyl polysilane, and react at 45-60℃ for 18-24 h. Then add phenolic resin and triethylamine, and continue the reaction for 6-10 h. Filter, wash the product with dichloromethane, dry, grind, and obtain modified silica aerogel.

[0009] Step (2): Add silicone rubber to a two-roll mill, plasticize and wrap the rolls, add modified silica aerogel, hydroxyl silicone oil, dicumyl peroxide, aluminum hydroxide, hollow glass microspheres, and high-silica fibers, thin pass, mix, sheet, and let stand at room temperature for 24-36 hours. Then place the material in a flat vulcanizing machine and vulcanize at 10-15 MPa and 175-190℃ for 15-20 minutes to obtain a composite material of silica aerogel modified rubber.

[0010] Furthermore, in step (1), the mass ratio of silica aerogel, chlorophenyl polysilane, phenolic resin, and triethylamine is 100:(5-25):(8-30):(2-8).

[0011] Furthermore, in step (2), the mass ratio of silicone rubber, modified silica aerogel, hydroxyl silicone oil, dicumyl peroxide, aluminum hydroxide, hollow glass microspheres, and high silica fiber is 100:(15-25):(3-5):(3-4):(30-38):(20-32):(10-16).

[0012] Furthermore, the preparation method of the rubber hose is as follows: a silica aerogel modified rubber composite material is coated on the outer layer of the hose, and then a water cloth or polyester film is wrapped around it. After wrapping, the hose is vulcanized in a vulcanizing tank. After exiting the tank, the water cloth or polyester film is peeled off and the inner core is extracted to obtain a fireproof, heat-insulating, anti-burning, and flame-retardant rubber hose with a specific structure.

[0013] (III) Beneficial Technical Effects:

[0014] This invention utilizes chlorophenyl polysilane and phenolic resin to modify silica aerogel and incorporates it into silicone rubber. The silica aerogel, composed of covalently linked nano-sized silica particles forming a three-dimensional network framework, possesses ultra-high porosity and nano-sized pores, inhibiting heat conduction. Simultaneously, the high melting point of silica and the high-temperature stability of the nano-framework ensure that it does not easily collapse at high temperatures, maintaining a long-term high-efficiency thermal insulation effect. The phenolic resin molecules contain numerous aromatic rings and hydroxyl groups, readily undergoing dehydration, cross-linking, and condensation reactions at high temperatures. Through the recombination of chemical bonds between molecular chains, a dense and thermally stable aromatic carbon structure is formed. This structure, on the one hand, blocks heat transfer to the material interior, slowing down the thermal decomposition rate of the substrate; on the other hand, it prevents the diffusion of combustible gases generated by substrate decomposition to the combustion interface. The char layer itself has strong high temperature resistance, is not easy to burn or collapse, and can maintain its barrier function for a long time, which improves the char residue rate of the material and greatly improves the flame retardant performance of the material. Chlorophenyl polysilane contains a large number of silicon chloride bonds, some of which react with the hydroxyl groups on the surface of silica aerogel, and some can be grafted with phenolic resin to play a bridging role. This allows the phenolic resin to combine with inorganic substances such as silica aerogel. The resulting char layer is more compact and has stronger thermal shock resistance due to the support of the inorganic phase, which further reduces the flame retardant failure caused by cracks or pores in the char layer. It not only improves the dispersibility of silica aerogel, but also allows phenolic resin to fully play its role, thereby improving the mechanical properties and burning performance of silicone rubber materials. Detailed Implementation

[0015] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application are all commercially available.

[0016] The preparation method of chlorophenyl polysilane is as follows: 20g of methylphenyl polysiloxane is added to 300mL of n-hexane, 53g of aluminum chloride is added at 0℃, and 32g of acetyl chloride is added dropwise while stirring. After stirring for 2 hours, the mixture is stirred at 25℃ for 2 hours. The mixture is then centrifuged, the precipitate is washed with n-hexane, and dried to obtain chlorophenyl polysilane. The reaction formula is:

[0017]

[0018] Example 1:

[0019] (1) Weigh 200g of silica aerogel and add it to 8L of dichloromethane. Sonicate for 40min, add 50g of chlorophenyl polysilane, react at 45℃ for 24h, then add 160g of phenolic resin and 160g of triethylamine, continue to react for 6h, filter, wash the product with dichloromethane, dry, grind, and obtain modified silica aerogel.

[0020] (2) Add 5kg of silicone rubber to a two-roll mill, plasticize and wrap the rolls, add 750g of modified silica aerogel, 150g of hydroxyl silicone oil, 200g of dicumyl peroxide, 1.9kg of aluminum hydroxide, 1.5kg of hollow glass microspheres, and 500g of high-silica fiber, thin pass, mix, sheet out, and let stand at room temperature for 24h. Then place the material in a flat vulcanizing machine and vulcanize at 15MPa and 190℃ for 15min to obtain a composite material of silica aerogel modified rubber.

[0021] Example 2:

[0022] (1) Weigh 200g of silica aerogel and add it to 5L of dichloromethane. Sonicate for 40min, add 10g of chlorophenyl polysilane, react at 60℃ for 18h, then add 600g of phenolic resin and 40g of triethylamine, continue to react for 10h, filter, wash the product with dichloromethane, dry, grind, and obtain modified silica aerogel.

[0023] (2) Add 5kg of silicone rubber to a two-roll mill, plasticize and wrap the rolls, add 900g of modified silica aerogel, 250g of hydroxyl silicone oil, 150g of dicumyl peroxide, 1.5kg of aluminum hydroxide, 1kg of hollow glass microspheres, and 800g of high-silica fiber, thin pass, mix, sheet out, and let stand at room temperature for 36h. Then place the material in a flat vulcanizing machine and vulcanize at 10MPa and 175℃ for 20min to obtain a composite material of silica aerogel modified rubber.

[0024] Example 3:

[0025] (1) Weigh 200g of silica aerogel and add it to 6L of dichloromethane. Sonicate for 50min, add 25g of chlorophenyl polysilane, react at 50℃ for 20h, then add 450g of phenolic resin and 80g of triethylamine, continue to react for 8h, filter, wash the product with dichloromethane, dry, grind, and obtain modified silica aerogel.

[0026] (2) Add 5 kg of silicone rubber to a two-roll mill, plasticize and wrap the rolls, add 1100 g of modified silica aerogel, 200 g of hydroxyl silicone oil, 180 g of dicumyl peroxide, 1.6 kg of aluminum hydroxide, 1.2 kg of hollow glass microspheres, and 600 g of high silica fiber, thin pass, mix, sheet out, and let stand at room temperature for 30 h. Then place the material in a flat vulcanizing machine and vulcanize at 12 MPa and 180 °C for 17 min to obtain a composite material of silica aerogel modified rubber.

[0027] Example 4:

[0028] (1) Weigh 200g of silica aerogel and add it to 7L of dichloromethane. Sonicate for 55min, add 30g of chlorophenyl polysilane, react at 55℃ for 22h, then add 550g of phenolic resin and 120g of triethylamine, continue to react for 7h, filter, wash the product with dichloromethane, dry, grind, and obtain modified silica aerogel.

[0029] (2) Add 5kg of silicone rubber to a two-roll mill, plasticize and wrap the rolls, add 1250g of modified silica aerogel, 170g of hydroxyl silicone oil, 160g of dicumyl peroxide, 1.8kg of aluminum hydroxide, 1.4kg of hollow glass microspheres, and 700g of high-silica fiber, pass through a thin sheet, mix, sheet out, and let stand at room temperature for 25h. Then place the material in a flat vulcanizing machine and vulcanize at 185℃ for 18min at 12MPa to obtain a composite material of silica aerogel modified rubber.

[0030] Comparative Example 1:

[0031] (1) Add 5kg of silicone rubber to a two-roll mill, plasticize and wrap the rolls, add 150g of hydroxyl silicone oil, 200g of dicumyl peroxide, 1.9kg of aluminum hydroxide, 1.5kg of hollow glass microspheres and 500g of high-silica fiber, thin pass, mix, sheet out, and let stand at room temperature for 24h. Then place the material in a flat vulcanizing machine and vulcanize at 15MPa and 190℃ for 15min to obtain rubber composite material.

[0032] Comparative Example 2:

[0033] (1) Add 5kg of silicone rubber to a two-roll mill, plasticize and wrap the rolls, add 750g of silica aerogel, 150g of hydroxyl silicone oil, 200g of dicumyl peroxide, 1.9kg of aluminum hydroxide, 1.5kg of hollow glass microspheres, and 500g of high-silica fiber, thin pass, mix, sheet out, and let stand at room temperature for 24h. Then place the material in a flat vulcanizing machine and vulcanize at 15MPa and 190℃ for 15min to obtain a composite material of silica aerogel modified rubber.

[0034] Comparative Example 3:

[0035] (1) Weigh 200g of silica aerogel and add it to 8L of dichloromethane. Sonicate for 40min, add 50g of trimethylchlorosilane, react at 45℃ for 24h, then add 160g of phenolic resin and 160g of triethylamine, continue to react for 6h, filter, wash the product with dichloromethane, dry, grind, and obtain modified silica aerogel.

[0036] (2) Add 5kg of silicone rubber to a two-roll mill, plasticize and wrap the rolls, add 750g of modified silica aerogel, 150g of hydroxyl silicone oil, 200g of dicumyl peroxide, 1.9kg of aluminum hydroxide, 1.5kg of hollow glass microspheres and 500g of high silica fiber, thin pass, mix, sheet out, and let stand at room temperature for 24h. Then place the material in a flat vulcanizing machine and vulcanize at 15MPa and 190℃ for 15min to obtain silica aerogel modified rubber composite material.

[0037] Hardness test: The test was conducted in accordance with GB / T 531.2-2009 "Test method for indentation hardness of vulcanized rubber or thermoplastic rubber - Part 2: Portable rubber international hardness tester method".

[0038] Thermal conductivity test: The test was conducted in accordance with GB / T 11205-2009 "Determination of thermal conductivity of rubber by hot wire method".

[0039] Limiting oxygen index and ablation rate tests: The tests were conducted in accordance with ASTM E285-08, "Standard Test Methods for Thermal Properties of Absorbable Materials".

[0040] Tensile strength and elongation at break tests: The tests were conducted in accordance with GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber".

[0041] Table 1 Performance Tests of Rubber Materials

[0042]

[0043]

[0044] In each embodiment, chlorophenyl polysilane and phenolic resin were used to modify silica aerogel and then incorporated into silicone rubber. The silica aerogel, composed of covalently linked nano-sized silica particles forming a three-dimensional network framework, possesses ultra-high porosity and nano-sized pores, inhibiting heat conduction. Simultaneously, the high melting point of silica and the high-temperature stability of the nano-framework ensure that it is not prone to structural collapse at high temperatures, maintaining a long-term high-efficiency thermal insulation effect. The phenolic resin molecules contain a large number of aromatic rings and hydroxyl groups, which readily undergo dehydration, cross-linking, and condensation reactions at high temperatures. Through the recombination of chemical bonds between molecular chains, a dense and thermally stable aromatic carbon structure is formed. This structure can, on the one hand, block heat transfer to the interior of the material, slowing down the thermal decomposition rate of the substrate; on the other hand, it can prevent the diffusion of combustible gases generated by substrate decomposition to the combustion interface. The char layer itself has strong high temperature resistance, is not easy to burn or collapse, and can maintain its barrier function for a long time, which improves the char residue rate of the material and greatly improves the flame retardant performance of the material. Chlorophenyl polysilane contains a large number of silicon chloride bonds, some of which react with the hydroxyl groups on the surface of silica aerogel, and some can be grafted with phenolic resin to play a bridging role. This allows the phenolic resin to combine with inorganic substances such as silica aerogel. The resulting char layer is more compact and has stronger thermal shock resistance due to the support of the inorganic phase, which further reduces the flame retardant failure caused by cracks or pores in the char layer. It not only improves the dispersibility of silica aerogel, but also allows phenolic resin to fully play its role, thereby improving the mechanical properties and burning performance of silicone rubber materials.

[0045] Compared with Example 1, Comparative Example 1 did not modify the silicone rubber in any way, but only added common flame retardants. The problems of poor mechanical properties and insufficient burning performance of silicone rubber itself were not solved, and it could not be used for application scenarios with higher requirements.

[0046] In Comparative Example 2, unmodified silica aerogel was added. Although silica aerogel itself has a certain high-temperature insulation effect, unmodified silica aerogel has disadvantages such as high brittleness, low strength, poor high-temperature resistance and complex high-temperature phase, which affect the mechanical properties and burning properties of silicone rubber composite material.

[0047] In Comparative Example 3, trimethylchlorosilane was used to modify silica aerogel, and phenolic resin was added simultaneously. Trimethylchlorosilane molecules contain only one silicon-chlorine bond, and after reacting with silica aerogel, they cannot be further grafted with phenolic resin. This results in the phenolic resin being removed during dichloromethane washing and unable to participate in the char formation process, leading to a decrease in the char residue rate of the material and failing to improve the char resistance of silicone rubber. However, after modification, the silica aerogel exhibits excellent dispersibility in silicone rubber, which can reduce the impact of silica aerogel on the mechanical properties of silicone rubber, allowing the material to maintain good mechanical properties.

[0048] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, and such modifications are protected by patent law as long as they fall within the scope of protection claimed in this application.

Claims

1. A method for preparing a composite material of silica aerogel-modified rubber, characterized in that, The preparation method is as follows: Step (1): Weigh silica aerogel and add it to dichloromethane. Sonicate the mixture, add chlorophenyl polysilane, react, then add phenolic resin and triethylamine, continue the reaction, filter, wash the product with dichloromethane, dry, grind, and obtain modified silica aerogel. The structural formula of the chlorophenyl polysilane is as follows: In the formula, x and y represent the degree of aggregation; Step (2): Add silicone rubber to a two-roll mill, plasticize and wrap the rolls, add modified silica aerogel, hydroxyl silicone oil, diisopropylbenzene peroxide, aluminum hydroxide, hollow glass microspheres, and high-silica fibers, thin pass through, mix, sheet out, and let stand at room temperature for 24-36 hours. Then place the material in a flat vulcanizing machine and vulcanize at 10-15 MPa to obtain a composite material of silica aerogel modified rubber.

2. The method for preparing the silica aerogel-modified rubber composite material according to claim 1, characterized in that, In step (1), the mass ratio of silica aerogel, chlorophenyl polysilane, phenolic resin, and triethylamine is 100:25:80:80, 100:5:300:20, 100:12.5:225:40, or 100:15:275:

60.

3. The method for preparing the silica aerogel-modified rubber composite material according to claim 1, characterized in that, The ultrasound time in step (1) is 40-60 minutes.

4. The method for preparing the silica aerogel-modified rubber composite material according to claim 1, characterized in that, The reaction temperature in step (1) is 45-60℃, and the reaction time is 18-24h; the reaction time continues for 6-10h.

5. The method for preparing the silica aerogel-modified rubber composite material according to claim 1, characterized in that, In step (2), the mass ratio of silicone rubber, modified silica aerogel, hydroxyl silicone oil, diisopropylbenzene peroxide, aluminum hydroxide, hollow glass microspheres, and high silica fiber is 100: (15-25): (3-5): (3-4): (30-38): (20-32): (10-16).

6. The method for preparing the silica aerogel-modified rubber composite material according to claim 1, characterized in that, The vulcanization temperature in step (2) is 175-190℃ and the time is 15-20min.

7. A hose made of a composite material of silica aerogel-modified rubber obtained by any one of the preparation methods described in claims 1-6.

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