A modified rfl dip solution, its preparation method and use

Abstract

The application provides a modified RFL dipping solution and a preparation method and application thereof, and relates to the technical field of fiber dipping. The application improves the modulus of the bonding interface by modifying the RFL dipping solution with silica aerogel, forms a nano-reinforced interface structure, and improves the bonding performance of the fiber fabric and rubber, so that the peeling strength and bonding performance are higher than the existing industry standard. The silica aerogel has a large specific surface area and a high porosity, has good dispersibility and suspensibility in the adhesive, and has a reinforcing effect. The silica aerogel can increase the roughness of the fiber surface and change the shape of the fiber surface to increase the bonding surface area, so as to improve the bonding performance of the fiber and the rubber.

Description

Technical Field

[0001] This invention relates to the field of fiber impregnation technology, and in particular to a modified RFL impregnation solution, its preparation method, and its application. Background Technology

[0002] With the development of the rubber industry, fiber / rubber products are increasingly appearing in people's lives. Fiber-rubber composites are composed of reinforcing fiber skeleton materials and rubber matrix. The good elasticity of the rubber matrix is ​​used to withstand the large deformation generated when the composite is subjected to force, while the fiber skeleton material is used to resist the damage caused by stress to the composite. In fiber / rubber composites, the interfacial adhesion performance is the main factor that determines the overall performance of the composite.

[0003] Fiber-reinforced rubber composites play a vital role in the rubber industry, and the adhesion between the fibers and the rubber matrix is ​​crucial to the safety and service life of rubber products. However, due to factors such as high modulus and surface inertness, the adhesion between high-performance fibers and the rubber matrix is ​​not ideal. In rubber industrial production, the application of fibers in rubber composites generally involves fiber impregnation. To achieve adhesion between fibers and the rubber matrix, which have significant differences in polarity and rigidity, the most common treatment method is traditional resorcinol-formaldehyde-latex (RFL) impregnation of the fiber skeleton material. After RFL impregnation, the fibers can form hydrogen bonds or chemical bonds with the rubber, thereby achieving good adhesion performance. Over the past few decades, researchers have continuously improved the RFL impregnation system by changing the three components of RFL, adding new components, and altering the impregnation steps; these are collectively referred to as modified RFL impregnation systems.

[0004] Patent CN110904684A discloses a nano-reinforced resorcinol-formaldehyde-latex impregnation system for fiber cord surface treatment and its preparation method. The nanofiller used is selected from at least one of attapulgite, nanocellulose, graphene oxide, montmorillonite, and clay. These nanofillers can be well dispersed in the impregnation solution and exhibit a certain degree of reactivity with it, enhancing the adhesion between the fiber and rubber. The viscosity of the impregnation system does not increase significantly after long-term storage at room temperature, which is beneficial for the long-term storage and transportation of the impregnation solution during the fiber skeleton material impregnation process. The impregnation solution preparation and fiber impregnation process are simple. After adding the nanofiller, the H-pull force increases from 93.7N to 102.6N, and the adhesion performance improves by approximately 10%.

[0005] Zou Li (Zou Li, Luo Peng, Sun Yan, Zhang Zhenxiu, Chen Gang, Wang Dongbin. Effect of nanofillers on the adhesion properties of aramid fiber and natural rubber. Rubber Industry, 2020, 67(01): 17-22.) added multi-walled carbon nanotubes (MWCNTs) to the RFL “two-bath” system, which increased the adhesion between aramid and natural rubber by 10%.

[0006] Although the aforementioned existing technologies have all improved the adhesion between fibers and rubber matrices to some extent, the improvement in adhesion performance is limited. Summary of the Invention

[0007] The purpose of this invention is to provide a modified RFL impregnation solution, its preparation method and application, which can significantly improve the bonding strength between fibers and rubber matrix, making its bonding performance higher than existing industry standards.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0009] The present invention provides a modified RFL impregnation solution, comprising, by weight, 100 parts of RFL impregnation solution, 0.5 to 10 parts of coupling agent surface-modified silica aerogel, and 5 to 100 parts of ethanol.

[0010] Preferably, the preparation method of the coupling agent surface-modified silica aerogel includes: mixing the coupling agent with ethanol and water, performing pre-hydrolysis to obtain a pre-hydrolysis product; mixing the pre-hydrolysis product with silica aerogel, and then modifying it to obtain a coupling agent surface-modified silica aerogel.

[0011] Preferably, the mass ratio of the coupling agent, ethanol and water is (0.01-0.3):(10-100):(0.01-2); and the mass ratio of the silica aerogel and the coupling agent is 1:(0.01-0.3).

[0012] Preferably, the coupling agent is a silane coupling agent.

[0013] Preferably, the silane coupling agent is at least one of MTMS, KH550, KH560, KH551, Al120, KH570, KH580, KH602 and KH791.

[0014] Preferably, the RFL impregnation solution comprises the following raw materials in parts by weight:

[0015] The mixture comprises 1-5 parts resorcinol, 1-7 parts of 37wt% formaldehyde solution, 0.5-3 parts of 10wt% sodium hydroxide solution, 40-100 parts water, 30-60 parts rubber latex, and 1-5 parts of 28wt% ammonia water; the solid content of the rubber latex is 30-50%.

[0016] This invention provides a method for preparing the modified RFL impregnation solution described above, comprising the following steps:

[0017] The surface-modified silica aerogel of the coupling agent was dispersed in ethanol, and then the resulting dispersion was mixed with RFL impregnation solution for modification to obtain modified RFL impregnation solution.

[0018] Preferably, the mixing modification includes sequential mechanical stirring for 0.5 to 1 hour and ultrasonic treatment for 0.1 to 1 hour.

[0019] This invention provides the application of the modified RFL impregnation liquid described in the above-described scheme or the modified RFL impregnation liquid prepared by the preparation method described in the above-described scheme in the preparation of fiber-reinforced rubber composite materials.

[0020] Preferably, the preparation method of the fiber-reinforced rubber composite material includes the following steps: impregnating the fiber canvas with modified RFL impregnation liquid, and then compounding the impregnated fiber canvas with a rubber matrix;

[0021] The fiber canvas is one or a blend of cotton fiber canvas, polyester canvas, nylon canvas, aramid canvas, and ultra-high molecular weight polyethylene fiber canvas.

[0022] The present invention provides a modified RFL impregnation solution, comprising, by weight, 100 parts of RFL impregnation solution, 0.5 to 10 parts of coupling agent surface-modified silica aerogel, and 5 to 100 parts of ethanol.

[0023] This invention employs silica aerogel with a coupling agent surface modification, grafting active groups (such as methyl, amino, imino, epoxy groups, and double bonds) onto the surface of the silica aerogel. This allows it to react with the active groups of the RFL impregnation liquid (hydroxymethyl and phenolic hydroxyl groups in phenolic resin), as well as with the active groups of fibers and rubber, thereby improving the adhesion between fiber fabrics and rubber.

[0024] Furthermore, this invention improves the modulus of the bonding interface by modifying the RFL impregnation solution with silica aerogel, forming a nano-reinforced interface structure to enhance the adhesion performance between fiber fabrics and rubber, resulting in peel strength and adhesion performance exceeding existing industry standards. Silica aerogel possesses a large specific surface area and high porosity, exhibiting excellent dispersibility, suspension properties, and reinforcing effects in adhesives. Silica aerogel can increase the roughness of the fiber surface and alter its shape to increase the bonding surface area, thereby improving the adhesion performance between fibers and rubber. The results of the embodiments show that, by modifying the RFL impregnation solution, the adhesion performance between fibers and the rubber matrix is ​​improved by up to 30.9% compared to standard RFL impregnation solutions.

[0025] The impregnation solution of this invention is highly practical and can be directly applied to existing impregnation processes and equipment, reducing the expenditure of manpower, material resources, and financial resources required for equipment and process modifications due to changes in the impregnation solution, and is easy to promote and use. Attached Figure Description

[0026] Figure 1 This is a photograph of the actual sample of the modified RFL impregnation solution peeling in Example 2;

[0027] Figure 2 A photograph of the actual sample peeled off with standard RFL impregnation solution, Comparative Example 1;

[0028] Figure 3 The peel strength comparison curves are for Example 2 and Comparative Example 1. Detailed Implementation

[0029] The present invention provides a modified RFL impregnation solution, comprising, by weight, 100 parts of RFL impregnation solution, 0.5 to 10 parts of coupling agent surface-modified silica aerogel, and 5 to 100 parts of ethanol.

[0030] Based on the weight parts of the RFL impregnation liquid, the raw materials for preparing the modified RFL impregnation liquid provided by the present invention include 0.5 to 10 parts of coupling agent surface-modified silica aerogel, preferably 1 to 9 parts, more preferably 2 to 8 parts, and even more preferably 4 to 6 parts.

[0031] In this invention, the preferred method for preparing the coupling agent surface-modified silica aerogel includes: mixing the coupling agent with ethanol and water, performing pre-hydrolysis to obtain a pre-hydrolysis product; mixing the pre-hydrolysis product with silica aerogel, and then performing modification to obtain the coupling agent surface-modified silica aerogel.

[0032] This invention involves mixing a coupling agent with ethanol and water, followed by pre-hydrolysis to obtain a pre-hydrolyzed product. In this invention, the coupling agent is preferably a silane coupling agent, and the silane coupling agent is preferably at least one selected from MTMS, KH550, KH560, KH551, Al120, KH570, KH580, KH602, and KH791. In this invention, the mass ratio of the coupling agent, ethanol, and water is preferably (0.01–0.3):(10–100):(0.01–2), more preferably (0.1–0.2):(30–50):(0.1–1). In this invention, the pre-hydrolysis is preferably carried out at room temperature, and the pre-hydrolysis time is preferably 0.5 h or more. Preferably, the coupling agent is added dropwise to ethanol, followed by the addition of water for mixing.

[0033] After obtaining the pre-hydrolyzed product, the present invention mixes the pre-hydrolyzed product with silica aerogel and then modifies it to obtain a silica aerogel with a coupling agent surface modified. In the present invention, the mass ratio of silica aerogel to coupling agent is preferably 1:(0.01-0.3), more preferably 1:(0.1-0.2); the mixing is preferably carried out under ultrasonic conditions, and the ultrasonication time is preferably 1 hour. The modification temperature is preferably 70°C; the modification is preferably carried out under stirring conditions, and the stirring speed is preferably 500 rpm; the modification time is preferably 4-5 hours. In the modification process, the silane coupling agent is grafted onto the surface of the silica aerogel. After the modification is completed, the present invention preferably centrifuges the obtained product repeatedly and dries it to obtain a silica aerogel with a coupling agent surface modified.

[0034] This invention employs silica aerogel with a coupling agent surface modification, grafting active groups (such as methyl, amino, imino, epoxy groups, and double bonds) onto the surface of the silica aerogel. This allows it to react with the active groups of the RFL impregnation liquid (hydroxymethyl and phenolic hydroxyl groups in phenolic resin), as well as with the active groups of fibers and rubber, thereby improving the adhesion between fiber fabrics and rubber.

[0035] Based on the weight parts of the RFL impregnation solution, the raw materials for preparing the modified RFL impregnation solution provided by the present invention include 5 to 100 parts of ethanol, preferably 20 to 90 parts, and more preferably 40 to 70 parts. In the present invention, the ethanol is preferably anhydrous ethanol; the ethanol is used to disperse the silica aerogel modified on the surface of the coupling agent.

[0036] In this invention, the RFL impregnation solution can be prepared using commercially available products or methods well-known in the art. Preferably, the solution is prepared and used immediately.

[0037] In this invention, the RFL impregnation solution preferably comprises the following raw materials in parts by weight:

[0038] The mixture comprises 1-5 parts resorcinol, 1-7 parts of 37wt% formaldehyde solution, 0.5-3 parts of 10wt% sodium hydroxide solution, 40-100 parts water, 30-60 parts rubber latex, and 1-5 parts of 28wt% ammonia water; the solid content of the rubber latex is 30-50%.

[0039] The raw materials for preparing the RFL impregnation solution provided by the present invention include 1 to 5 parts of resorcinol, preferably 2 to 4 parts, by weight.

[0040] Based on the weight percentage of resorcinol, the raw materials for preparing the RFL impregnation solution provided by the present invention include 1 to 7 parts of 37wt% formaldehyde solution, preferably 2 to 6 parts, and more preferably 3 to 5 parts.

[0041] Based on the weight percentage of resorcinol, the raw materials for preparing the RFL impregnation solution provided by the present invention include 0.5 to 3 parts of a 10 wt% sodium hydroxide solution, preferably 1 to 2.5 parts, and more preferably 1.5 to 2.0 parts. In the present invention, the resorcinol and formaldehyde are used as reaction raw materials for phenolic resin, and sodium hydroxide is used as a catalyst for the reaction.

[0042] Based on the weight parts of resorcinol, the raw materials for preparing the RFL impregnation solution provided by the present invention include 40-100 parts of water, preferably 50-90 parts, and more preferably 60-80 parts. In the present invention, the water is preferably deionized water.

[0043] Based on the weight parts of resorcinol, the raw materials for preparing the RFL impregnation solution provided by the present invention include 30 to 60 parts of rubber latex, preferably 40 to 50 parts. In the present invention, the solid content of the rubber latex is 40%. In the present invention, the rubber latex preferably includes at least one of butyl rubber latex, styrene-butadiene latex, chloroprene latex, and nitrile rubber latex.

[0044] Based on the weight percentage of resorcinol, the raw materials for preparing the RFL impregnation solution provided by the present invention include 1 to 5 parts, preferably 2 to 4 parts, of 28 wt% ammonia water. In the present invention, the ammonia water serves to remove unreacted formaldehyde from the condensation reaction between formaldehyde and resorcinol.

[0045] In this invention, the method for preparing the RFL impregnation solution preferably includes the following steps:

[0046] Sodium hydroxide solution, resorcinol and formaldehyde solution are mixed to carry out phenolic condensation reaction to obtain phenolic resin solution;

[0047] The phenolic resin solution, rubber latex and water are mixed, and ammonia is added to the resulting mixed solution to adjust the pH to 8-9, thus obtaining the RFL impregnation solution.

[0048] This invention involves mixing sodium hydroxide solution, resorcinol, and formaldehyde solution to perform a phenolic condensation reaction, thereby obtaining a phenolic resin solution.

[0049] In this invention, the mixing of sodium hydroxide solution, resorcinol, and formaldehyde solution is preferably carried out by first adding resorcinol to the sodium hydroxide solution until the resorcinol is completely dissolved, and then adding the formaldehyde solution. In this invention, the temperature of the phenolic condensation reaction is preferably 25–40°C, and the time is preferably 5–7 hours. In this invention, the phenolic resin obtained by the phenolic condensation reaction is a linear phenolic resin.

[0050] After obtaining the phenolic resin solution, the present invention mixes the phenolic resin solution, rubber latex and water, and adds ammonia water to the resulting mixed solution to adjust the pH value to 8-9, thereby obtaining the RFL impregnation solution.

[0051] In this invention, mixing the phenolic resin solution, rubber latex, and water preferably includes: mixing the rubber latex and water, and then adding the phenolic resin solution to the resulting mixture.

[0052] After adding the phenolic resin solution, the present invention preferably stirs at room temperature for 20 hours, and continuously adds ammonia water during the stirring process to adjust the pH value to 8-9, so as to obtain the RFL impregnation solution.

[0053] This invention provides a method for preparing the modified RFL impregnation solution described above, comprising the following steps:

[0054] The surface-modified silica aerogel of the coupling agent was dispersed in ethanol, and then the resulting dispersion was mixed with RFL impregnation solution for modification to obtain modified RFL impregnation solution.

[0055] In this invention, the mixing modification preferably includes sequential mechanical stirring for 0.5 to 1 hour and ultrasonic treatment for 0.1 to 1 hour.

[0056] This invention improves the modulus of the bonding interface by modifying RFL impregnation liquid with silica aerogel, forming a nano-reinforced interface structure to enhance the adhesion between fiber fabrics and rubber, resulting in peel strength and adhesion performance exceeding existing industry standards. Silica aerogel possesses a large specific surface area and high porosity, exhibiting excellent dispersibility, suspension properties, and reinforcing effects in adhesives. Silica aerogel can increase the roughness of the fiber surface and alter its shape to increase the bonding surface area, thereby improving the adhesion between fibers and rubber.

[0057] This invention provides the application of the modified RFL impregnation liquid described in the above-described scheme or the modified RFL impregnation liquid prepared by the preparation method described in the above-described scheme in the preparation of fiber-reinforced rubber composite materials.

[0058] In this invention, the preferred method for preparing the fiber-reinforced rubber composite material includes the following steps: impregnating the fiber canvas with a modified RFL impregnation solution, and then combining the impregnated fiber canvas with a rubber matrix;

[0059] The fiber canvas is one or a blend of cotton fiber canvas, polyester canvas, nylon canvas, aramid canvas, and ultra-high molecular weight polyethylene fiber canvas.

[0060] The present invention does not have any special requirements for the impregnation and lamination process; any impregnation and lamination process well known in the art can be used.

[0061] The modified RFL impregnation solution, its preparation method, and its application provided by the present invention will be described in detail below with reference to the embodiments. However, these should not be construed as limiting the scope of protection of the present invention.

[0062] The detailed preparation process of the silica aerogels surface-modified with silane coupling agents used in Examples 1-3 and Comparative Example 2 is as follows:

[0063] Following a mass ratio of silica aerogel: anhydrous ethanol: silane coupling agent MTMS: deionized water of 1:40:0.05:0.25, a certain amount of anhydrous ethanol was first weighed into a large beaker. Then, the corresponding amount of coupling agent was accurately weighed and added dropwise to the ethanol using an analytical balance, followed by the corresponding amount of deionized water. The beaker was then left to stand in a cool, dark place at room temperature for pre-hydrolysis. After 0.5 hours, silica aerogel was added to the pre-hydrolysis product, and the mixture was sonicated for 1 hour. The solution was then transferred to a three-necked flask, and the reaction was continued with stirring at 70°C and 500 rpm for 4 hours. The reaction product was then repeatedly centrifuged and dried to obtain silica aerogel modified with silane coupling agent.

[0064] The detailed preparation process of the silica aerogel surface-modified with silane coupling agent used in Example 4 is as follows:

[0065] Following a mass ratio of silica aerogel: anhydrous ethanol: silane coupling agent KH560: deionized water of 1:40:0.05:0.25, a certain amount of anhydrous ethanol was first weighed into a large beaker. Then, the corresponding amount of coupling agent was accurately weighed and added dropwise to the ethanol using an analytical balance, followed by the corresponding amount of deionized water. The beaker was then left to stand in a cool, dark place at room temperature for pre-hydrolysis. After 0.5 hours, silica aerogel was added to the pre-hydrolysis product, and the mixture was sonicated for 1 hour. The solution was then transferred to a three-necked flask, and the reaction was continued with stirring at 70°C and 500 rpm for 4 hours. The reaction product was then repeatedly centrifuged and dried to obtain silica aerogel modified with silane coupling agent.

[0066] Comparative Example 1

[0067] The standard RFL impregnation solution formulation comprises the following raw materials in parts by weight: 2 parts resorcinol, 3 parts formaldehyde (37wt%), 0.5 parts sodium hydroxide (10wt%), 50 parts deionized water, 43 parts butyl-pyridine latex (40wt%), and 2 parts ammonia (28wt%).

[0068] Preparation of standard RFL impregnation solution: Distilled water and sodium hydroxide were added to a reaction vessel and stirred evenly at 25°C until the sodium hydroxide was fully dissolved, resulting in a 10 wt% sodium hydroxide solution. Resorcinol was added to the 10 wt% sodium hydroxide solution and stirred for 20 min until completely dissolved. Then, 37 wt% formaldehyde was added, and the reaction temperature was controlled at 25°C for 6 h to obtain an RF resin solution. Butadiene-pyridine latex and deionized water were added to the reaction vessel and mixed evenly. The prepared RF resin solution was then added, and the temperature was controlled at 25°C for 20 h. The pH of the solution was adjusted to 8-9 by continuously adding ammonia water to obtain the standard RFL impregnation solution.

[0069] Example 1

[0070] The modified RFL impregnation solution formulation, by weight, comprises 100 parts RFL impregnation solution, 1.5 parts silica aerogel modified with silane coupling agent, and 15 parts anhydrous ethanol. The preparation process of the RFL impregnation solution is the same as that of the standard RFL impregnation solution in Comparative Example 1.

[0071] The surface-modified silica aerogel of the coupling agent was added to anhydrous ethanol and fully dispersed. Then it was added to the reaction vessel of RFL impregnation solution and mechanically stirred at room temperature for 30 min. Then it was ultrasonically treated for 10 min to mix it evenly, thus obtaining the modified RFL impregnation solution.

[0072] Example 2

[0073] The modified RFL impregnation solution formulation, by weight, comprises 100 parts RFL impregnation solution, 2 parts silane coupling agent surface-modified silica aerogel, and 20 parts anhydrous ethanol. The preparation process of the RFL impregnation solution is the same as that of the standard RFL impregnation solution in Comparative Example 1.

[0074] The surface-modified silica aerogel of the coupling agent was added to anhydrous ethanol and fully dispersed. Then it was added to a reactor containing RFL impregnation solution and mechanically stirred at room temperature for 30 min. Then it was ultrasonically treated for 10 min to mix it evenly, thus obtaining the modified RFL impregnation solution.

[0075] Example 3

[0076] The modified RFL impregnation solution formulation, by weight, comprises 100 parts RFL impregnation solution, 2.5 parts silica aerogel modified with silane coupling agent, and 25 parts anhydrous ethanol. The preparation process of the RFL impregnation solution is the same as that of the standard RFL impregnation solution in Comparative Example 1.

[0077] The surface-modified silica aerogel of the coupling agent was added to anhydrous ethanol and fully dispersed. Then it was added to a reactor containing RFL impregnation solution and mechanically stirred at room temperature for 30 min. Then it was ultrasonically treated for 10 min to mix it evenly, thus obtaining the modified RFL impregnation solution.

[0078] Example 4

[0079] The modified RFL impregnation solution formulation, by weight, comprises 100 parts RFL impregnation solution, 1.5 parts silica aerogel (KH560 modified) with silane coupling agent surface modification, and 25 parts anhydrous ethanol. The preparation process of the RFL impregnation solution is the same as that of the standard RFL impregnation solution in Comparative Example 1.

[0080] The surface-modified silica aerogel of the coupling agent was added to anhydrous ethanol and fully dispersed. Then it was added to a reactor containing RFL impregnation solution and mechanically stirred at room temperature for 30 min. Then it was ultrasonically treated for 10 min to mix it evenly, thus obtaining the modified RFL impregnation solution.

[0081] Comparative Example 2

[0082] The modified RFL impregnation solution formulation, by weight, comprises 100 parts of RFL impregnation solution, 15 parts of silica aerogel modified with silane coupling agent, and 150 parts of anhydrous ethanol.

[0083] The surface-modified silica aerogel of the coupling agent was added to anhydrous ethanol and fully dispersed. Then it was added to a reactor containing RFL impregnation solution and mechanically stirred at room temperature for 30 min. Then it was ultrasonically treated for 10 min to mix it evenly, thus obtaining the modified RFL impregnation solution.

[0084] Performance testing:

[0085] The canvas was impregnated using the impregnation solutions prepared in Examples 1-4 and Comparative Examples 1-2, respectively: the polyester fiber canvas was soaked in anhydrous ethanol at room temperature for 10 minutes to remove the oil on the surface of the fiber fabric, then rinsed three times with deionized water and dried; the pretreated fiber fabric was immersed in the above-prepared impregnation solution at room temperature for 2 minutes and calendered for 1 minute; the impregnated fiber fabric was dried at 140°C for 10 minutes to remove the moisture from the fiber fabric; the dried fiber fabric was heat-treated at 240°C for 2 minutes to obtain the finished product.

[0086] Preparation of peel test specimens: The impregnated fiber fabric was cut into 25cm × 25cm pieces. A 4mm thick layer of pre-mixed adhesive rubber (self-made) was applied to both the top and bottom of the fabric. The specimens were then placed on a flat vulcanizing machine for vulcanization at 150℃, 15MPa, and 40min. After vulcanization, the peel strength was prepared and tested according to GB / T6759-2013 "Test Method for Interlayer Adhesion Strength of Conveyor Belts". Figure 1 This is a photograph of the actual sample of the modified RFL impregnation solution peeling in Example 2; Figure 2 A photograph of the actual sample peeled off with standard RFL impregnation solution, Comparative Example 1; Figure 3 The peel strength comparison curves are for Example 2 and Comparative Example 1.

[0087] The performance results of Examples 1-4 and Comparative Examples 1-2 are shown in Table 1.

[0088] Table 1: Comparison of adhesive properties of samples obtained from the examples and comparative examples

[0089] Peel strength (N / mm) Growth rate compared to standard RFL Example 1 11.79 23.1％ Example 2 12.54 30.9％ Example 3 10.56 10.2％ Example 4 12.01 25.3％ Comparative Example 1 9.58 — Comparative Example 2 7.62 -20.5％

[0090] As can be seen from the data in Table 1 of Examples 1-4 and Comparative Example 1, the modified RFL impregnation systems of the present invention, by adding modified silica aerogel to the impregnation solution, have a simple and effective preparation process. This not only improves the adhesive performance—by up to approximately 30% compared to the standard RFL impregnation solution—but also does not affect production efficiency. However, as can be seen from the results of Examples 1-4 and Comparative Example 2, adding too much silica aerogel results in poor dispersibility in the RFL impregnation solution, severe aerogel agglomeration, stress concentration, and reduced adhesive performance.

[0091] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A modified RFL impregnation solution, characterized in that, By weight, it includes 100 parts of RFL impregnation solution, 0.5-10 parts of surface-modified silica aerogel with coupling agent, and 5-100 parts of ethanol; The preparation method of the coupling agent surface-modified silica aerogel includes: mixing the coupling agent with ethanol and water, performing pre-hydrolysis to obtain a pre-hydrolysis product; mixing the pre-hydrolysis product with silica aerogel, and then modifying it to obtain a coupling agent surface-modified silica aerogel. The coupling agent is a silane coupling agent.

2. The modified RFL impregnation solution according to claim 1, characterized in that, The mass ratio of the coupling agent, ethanol and water is (0.01~0.3):(10~100):(0.01~2); the mass ratio of the silica aerogel and the coupling agent is 1:(0.01~0.3).

3. The modified RFL impregnation solution according to claim 1, characterized in that, The silane coupling agent is at least one of MTMS, KH550, KH560, KH551, A1120, KH570, KH580, KH602 and KH791.

4. The modified RFL impregnation solution according to claim 1, characterized in that, The RFL impregnation solution comprises the following raw materials in parts by weight: The mixture comprises 1-5 parts resorcinol, 1-7 parts of 37 wt% formaldehyde solution, 0.5-3 parts of 10 wt% sodium hydroxide solution, 40-100 parts water, 30-60 parts rubber latex, and 1-5 parts of 28 wt% ammonia solution; the solid content of the rubber latex is 30-50%.

5. The method for preparing the modified RFL impregnation solution according to any one of claims 1 to 4, characterized in that, Includes the following steps: The surface-modified silica aerogel of the coupling agent was dispersed in ethanol, and then the resulting dispersion was mixed with RFL impregnation solution for modification to obtain modified RFL impregnation solution.

6. The preparation method according to claim 5, characterized in that, The hybrid modification includes sequential mechanical stirring for 0.5 to 1 h and ultrasonic treatment for 0.1 to 1 h.

7. The application of the modified RFL impregnation liquid according to any one of claims 1 to 4 or the modified RFL impregnation liquid prepared by the preparation method according to any one of claims 5 to 6 in the preparation of fiber-reinforced rubber composites.

8. The application according to claim 7, characterized in that, The preparation method of the fiber-reinforced rubber composite material includes the following steps: impregnating the fiber canvas with modified RFL impregnation liquid, and then compounding the impregnated fiber canvas with a rubber matrix; The fiber canvas is one or a blend of cotton fiber canvas, polyester canvas, nylon canvas, aramid canvas, and ultra-high molecular weight polyethylene fiber canvas.

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