CN117721638A

CN117721638A - Modified RFL impregnating solution and preparation method and application thereof

Info

Publication number: CN117721638A
Application number: CN202211604454.0A
Authority: CN
Inventors: 何宏伟; 高志; 杨泽光; 史志浩; 贾兰; 余雯雯; 刘付永
Original assignee: Taiyuan University of Technology
Current assignee: Taiyuan University of Technology
Priority date: 2022-12-13
Filing date: 2022-12-13
Publication date: 2024-03-19

Abstract

The invention provides a modified RFL impregnating solution, a preparation method and application thereof, and relates to the technical field of fiber impregnation. According to the invention, the silica aerogel modified RFL impregnating solution is used for improving the modulus of an adhesive interface, so that a nano reinforced interface structure is formed, and the adhesive property of the fiber fabric and rubber is improved, so that the peel strength and the adhesive property of the fiber fabric are higher than those of the existing industry standard. The silica aerogel has large specific surface area and high void ratio, has good dispersibility and suspension property in adhesives and reinforcing effect, and can increase the coarseness of the fiber surface and change the shape of the fiber surface to increase the bonding surface area, thereby improving the bonding performance of the fiber and rubber.

Description

Modified RFL impregnating solution and preparation method and application thereof

Technical Field

The invention relates to the technical field of fiber dipping, in particular to a modified RFL dipping solution and a preparation method and application thereof.

Background

With the development of rubber industry, fiber/rubber products are increasingly appeared in the life of people, fiber rubber composite materials are formed by combining reinforced fiber framework materials and rubber matrixes, wherein the good elasticity of the rubber matrixes is used for bearing large deformation generated when the composite materials are stressed, the fiber framework materials are used for resisting the damage of stress to the composite materials due to the higher strength and rigidity of the fiber framework materials, and in the fiber/rubber composite materials, the interfacial adhesion performance is a main factor for determining the comprehensive performance of the composite materials.

Fiber reinforced rubber composites play a very important role in the rubber industry, and the quality of adhesion between the two is a key to determine the safety and service life of rubber products. However, the adhesion of high performance fibers to the rubber matrix is not ideal due to high modulus and surface inertness. In the rubber industry, the use of fibers in rubber composites is typically subjected to a fiber impregnation treatment, the most common treatment being the conventional resorcinol-formaldehyde-latex (RFL) impregnation treatment of the fiber matrix material for bonding between the fibers and the rubber matrix, which are of very different polarity and rigidity. After RFL impregnation, the fibers can form hydrogen bonds or chemical bonds with the rubber to achieve good adhesive properties, and in the course of the last decades, people continuously improve the RFL impregnation system by changing the three components of the RFL, adding new components, changing the impregnation step and the like, which are collectively called as modified RFL impregnation systems.

Patent CN110904684a discloses a nano-reinforced resorcinol-formaldehyde-latex dipping system for surface treatment of fiber cords and a preparation method thereof, wherein nano-filler is selected from at least one of attapulgite, nanocellulose, graphene oxide, montmorillonite and clay. The nano fillers can be well dispersed in the dipping liquid, have certain reactivity with the dipping liquid, and enhance the bonding performance of the fiber and the rubber. The viscosity of the dipping system is not greatly increased when the dipping system is placed for a long time under the condition of room temperature, the long-term storage and transportation of the dipping solution in the dipping production process of the fiber framework material are facilitated, the dipping solution preparation and the fiber dipping process are simple, the H extraction force is improved from 93.7N to 102.6N after the nano filler is added, and the adhesive property is improved by about 10%.

Li (Li, luo Peng, sun, zhang Zhenxiu, stiffness, wang Dongbin. Influence of nanofiller on the adhesion properties of aramid fibers to natural rubber. Rubber industry, 2020, 67 (01): 17-22.) the adhesion of aramid fibers to NR is improved by 10% by adding multiwall carbon nanotubes (MWCNTs) to an RFL "two bath" system.

The prior art increases the adhesion performance of the fiber and the rubber matrix to a certain extent, but the improvement range of the adhesion performance is limited.

Disclosure of Invention

The invention aims to provide a modified RFL impregnating solution, a preparation method and application thereof, which can obviously improve the adhesive strength of fibers and a rubber matrix and enable the adhesive property of the fiber and the rubber matrix to be higher than the existing industry standard.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a modified RFL impregnating solution, which comprises, by weight, 100 parts of the RFL impregnating solution, 0.5-10 parts of a coupling agent surface modified silica aerogel and 5-100 parts of ethanol.

Preferably, the preparation method of the coupling agent surface modified silica aerogel comprises the following steps: mixing a coupling agent with ethanol and water, and carrying out prehydrolysis to obtain a prehydrolysis product; and mixing the prehydrolysis product with the silica aerogel, and then modifying to obtain the silica aerogel with the surface modified by the coupling agent.

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

Preferably, the coupling agent is a silane coupling agent.

Preferably, the silane coupling agent is at least one of MTMS, KH550, KH560, KH551, A1120, KH570, KH580, KH602 and KH 791.

Preferably, the RFL impregnating solution comprises the following preparation raw materials in parts by weight:

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

The invention provides a preparation method of the modified RFL impregnating solution, which comprises the following steps:

dispersing the silica aerogel with the surface modified by the coupling agent into ethanol, and then mixing and modifying the obtained dispersion liquid with the RFL impregnating solution to obtain the modified RFL impregnating solution.

Preferably, the mixing modification comprises mechanical stirring for 0.5-1 h and ultrasonic treatment for 0.1-1 h in sequence.

The invention provides application of the modified RFL impregnating solution prepared by the scheme or the preparation method of the modified RFL impregnating solution in preparation of fiber reinforced rubber composite materials.

Preferably, the preparation method of the fiber reinforced rubber composite material comprises the following steps: dipping the fiber canvas by adopting modified RFL dipping liquid, and then compounding the dipped fiber canvas with a rubber matrix;

the fiber canvas is one or mixed woven canvas selected from cotton fiber canvas, polyester canvas, nylon canvas, aramid canvas and ultra-high molecular weight polyethylene fiber canvas.

The invention adopts the silica aerogel with the surface modified by the coupling agent, and leads the surface of the silica aerogel to be grafted with active groups (such as methyl, amino, imino, epoxy groups and double bonds), so that the silica aerogel can react with active groups of RFL impregnating solution (hydroxymethyl and phenolic hydroxyl in phenolic resin) and also react with active groups of fiber and rubber, thereby improving the adhesive property between fiber fabric and rubber.

In addition, the silica aerogel modified RFL impregnating solution is used for improving the modulus of an adhesive interface to form a nano reinforced interface structure so as to improve the adhesive property of the fiber fabric and rubber, and the peel strength and the adhesive property of the fiber fabric are higher than the existing industry standard. The silica aerogel has large specific surface area and high void ratio, has good dispersibility and suspension property in adhesives and reinforcing effect, and can increase the coarseness of the fiber surface and change the shape of the fiber surface to increase the bonding surface area, thereby improving the bonding performance of the fiber and rubber. The results of the examples show that the adhesive properties of the fiber and rubber matrix are improved by 30.9% at most compared with the standard RFL impregnating solution by modifying the RFL impregnating solution.

The impregnating solution has strong practicability, can be directly applied to the existing impregnation process and equipment, reduces the expenditure of manpower, material resources and financial resources caused by equipment and process transformation due to the change of the impregnation solution, and is easy to popularize and use.

Drawings

FIG. 1 is a photograph of a modified RFL dip strip sample of example 2;

FIG. 2 is a photograph of a sample of comparative example 1 standard RFL dip strip;

FIG. 3 is a graph showing the peel strength comparison between example 2 and comparative example 1.

Detailed Description

Based on the weight parts of the RFL impregnating solution, the preparation raw materials of the modified RFL impregnating solution provided by the invention comprise 0.5-10 parts, preferably 1-9 parts, more preferably 2-8 parts, and even more preferably 4-6 parts of silica aerogel modified by the surface of the coupling agent.

In the present invention, the preparation method of the coupling agent surface-modified silica aerogel preferably comprises: mixing a coupling agent with ethanol and water, and carrying out prehydrolysis to obtain a prehydrolysis product; and mixing the prehydrolysis product with the silica aerogel, and then modifying to obtain the silica aerogel with the surface modified by the coupling agent.

The invention mixes the coupling agent with ethanol and water to pre-hydrolyze, and the pre-hydrolyzed product is obtained. In the present invention, the coupling agent is preferably a silane coupling agent, and the silane coupling agent is preferably at least one of MTMS, KH550, KH560, KH551, a1120, KH570, KH580, KH602, and KH 791. In the invention, the mass ratio of the coupling agent, the ethanol and the water is preferably (0.01-0.3): 10-100): (0.01-2), more preferably (0.1-0.2): 30-50): (0.1-1). In the present invention, the pre-hydrolysis is preferably performed under room temperature conditions, and the time of the pre-hydrolysis is preferably 0.5h or more. The present invention preferably drops the coupling agent into ethanol and then mixes with water.

After the prehydrolysis product is obtained, the prehydrolysis product and the silica aerogel are mixed and then modified, so that the silica aerogel with the surface modified by the coupling agent is obtained. In the invention, the mass ratio of the silica aerogel to the coupling agent is preferably 1: (0.01 to 0.3), more preferably 1: (0.1 to 0.2); in the present invention, the mixing is preferably performed under ultrasonic conditions, and the time of the ultrasonic treatment is preferably 1h. In the present invention, the temperature of the modification is preferably 70 ℃; the modification is preferably carried out under stirring conditions, the rotational speed of the stirring preferably being 500rpm; the modification time is preferably 4 to 5 hours. In the modification process, the silane coupling agent is grafted to the surface of the silica aerogel. After the modification is completed, the obtained product is preferably repeatedly centrifuged and dried to obtain the silica aerogel with the surface modified by the coupling agent.

Based on the weight parts of the RFL impregnating solution, the preparation raw materials of the modified RFL impregnating solution provided by the invention comprise 5-100 parts of ethanol, preferably 20-90 parts, and more preferably 40-70 parts. In the present invention, the ethanol is preferably absolute ethanol; the ethanol is used for dispersing the silica aerogel with the surface modified by the coupling agent.

In the present invention, the RFL impregnating solution may be prepared by commercially available products well known in the art or by a preparation method well known in the art. The present invention is preferably ready-to-use.

In the invention, the RFL impregnating solution preferably comprises the following preparation raw materials in parts by weight:

The RFL impregnating solution provided by the invention comprises 1-5 parts of resorcinol, preferably 2-4 parts of resorcinol.

The preparation raw materials of the RFL impregnating solution provided by the invention comprise 1-7 parts by weight of 37wt% formaldehyde solution, preferably 2-6 parts by weight, and more preferably 3-5 parts by weight based on the resorcinol.

The RFL impregnating solution provided by the invention comprises 0.5-3 parts by weight of 10wt% sodium hydroxide solution, preferably 1-2.5 parts by weight, and more preferably 1.5-2.0 parts by weight based on the resorcinol. In the invention, resorcinol and formaldehyde are used as reaction raw materials of phenolic resin, and sodium hydroxide is used as a catalyst of the reaction.

The RFL impregnating solution provided by the invention is prepared from 40-100 parts of water, preferably 50-90 parts, and more preferably 60-80 parts by weight of resorcinol. In the present invention, the water is preferably deionized water.

Based on the weight parts of resorcinol, the RFL impregnating solution provided by the invention is prepared from 30-60 parts of rubber latex, preferably 40-50 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 butadiene-pyridine latex, styrene-butadiene latex, neoprene latex and nitrile latex.

Based on the weight parts of resorcinol, the preparation raw materials of the RFL impregnating solution provided by the invention comprise 1-5 parts by weight of 28wt% ammonia water, and preferably 2-4 parts by weight. In the present invention, the ammonia functions to remove unreacted formaldehyde of the condensation reaction of formaldehyde and resorcinol.

In the present invention, the preparation method of the RFL impregnating solution preferably includes the following steps:

mixing sodium hydroxide solution, resorcinol and formaldehyde solution, and performing phenolic aldehyde condensation reaction to obtain phenolic resin solution;

mixing the phenolic resin solution, the rubber latex and water, and adding ammonia water into the obtained mixed solution to adjust the pH value to 8-9, thereby obtaining the RFL impregnating solution.

The invention mixes sodium hydroxide solution, resorcinol and formaldehyde solution, and carries out phenolic aldehyde condensation reaction to obtain phenolic resin solution.

In the present invention, the mixing of sodium hydroxide solution, resorcinol and formaldehyde solution is preferably: resorcinol is added to sodium hydroxide solution until resorcinol is completely dissolved, and then formaldehyde solution is added. In the present invention, the temperature of the phenol condensation reaction is preferably 25 to 40℃and the time is preferably 5 to 7 hours. In the present invention, the phenolic resin obtained by the phenolic condensation reaction is a phenolic resin of a linear structure.

After the phenolic resin solution is obtained, the phenolic resin solution, the rubber latex and water are mixed, and ammonia water is added into the obtained mixed solution to adjust the pH value to 8-9, so as to obtain the RFL impregnating solution.

In the present invention, mixing the phenolic resin solution, the rubber latex and the water preferably comprises: after mixing the rubber latex with water, a phenolic resin solution is added to the resulting mixture.

After the phenolic resin solution is added, the invention is preferably stirred for 20 hours under normal temperature, and ammonia water is continuously added in the stirring process to adjust the pH value to 8-9, thus obtaining the RFL impregnating solution.

In the invention, the mixing modification preferably comprises mechanical stirring for 0.5-1 h and ultrasonic treatment for 0.1-1 h in sequence.

According to the invention, the silica aerogel modified RFL impregnating solution is used for improving the modulus of an adhesive interface, so that a nano reinforced interface structure is formed, and the adhesive property of the fiber fabric and rubber is improved, so that the peel strength and the adhesive property of the fiber fabric are higher than those of the existing industry standard. The silica aerogel has large specific surface area and high void ratio, has good dispersibility and suspension property in adhesives and reinforcing effect, and can increase the coarseness of the fiber surface and change the shape of the fiber surface to increase the bonding surface area, thereby improving the bonding performance of the fiber and rubber.

In the present invention, the preparation method of the fiber-reinforced rubber composite material preferably includes the steps of: dipping the fiber canvas by adopting modified RFL dipping liquid, and then compounding the dipped fiber canvas with a rubber matrix;

The present invention is not particularly limited to the impregnation and compounding process described, and impregnation and compounding processes well known in the art may be employed.

The modified RFL impregnating solution, the preparation method and application thereof provided by the invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of the invention.

The silane coupling agent surface-modified silica aerogels used in examples 1 to 3 and comparative example 2 were prepared in detail by the following steps:

according to the silica aerogel: absolute ethyl alcohol: silane coupling agent MTMS: the mass ratio of deionized water is 1:40:0.05: and (2) weighing a certain amount of absolute ethyl alcohol by using a large beaker at a ratio of 0.25, accurately weighing a corresponding amount of coupling agent by using an analytical balance, dripping the coupling agent into the ethyl alcohol, adding a corresponding amount of deionized water, and standing the beaker at a shade place at room temperature for pre-hydrolysis. Adding silicon dioxide aerogel into the prehydrolysis product after 0.5h, carrying out ultrasonic treatment for 1h, transferring the solution into a three-neck flask, and continuously stirring at 70 ℃ and 500rpm for 4h. And then repeatedly centrifuging and drying the reaction product to obtain the silicon dioxide aerogel with the surface modified by the silane coupling agent.

The silane coupling agent used in example 4 was surface-modified silica aerogel, which was prepared in detail by the following procedure:

according to the silica aerogel: absolute ethyl alcohol: silane coupling agent KH560: the mass ratio of deionized water is 1:40:0.05:0.25, firstly weighing a certain amount of absolute ethyl alcohol by using a large beaker, accurately weighing a corresponding amount of coupling agent by using an analytical balance, dripping the coupling agent into the ethanol, adding a corresponding amount of deionized water, standing the beaker at room temperature, performing prehydrolysis at a shade place, adding silica aerogel into a prehydrolysis product after 0.5h, transferring the solution into a three-neck flask after ultrasonic treatment for 1h, and continuously stirring at 70 ℃ and 500rpm for reaction for 4h. And then repeatedly centrifuging and drying the reaction product to obtain the silicon dioxide aerogel with the surface modified by the silane coupling agent.

Comparative example 1

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

Standard RFL dip preparation: distilled water and sodium hydroxide are added into a reaction kettle and stirred uniformly at 25 ℃, and 10wt% of sodium hydroxide solution is obtained after the sodium hydroxide is fully dissolved; adding resorcinol into 10wt% sodium hydroxide solution, stirring for 20min to dissolve completely, adding 37wt% formaldehyde, controlling the reaction temperature to 25 ℃, and reacting for 6h to obtain RF resin solution; adding the butadiene-pyridine latex and deionized water into a reaction kettle, uniformly mixing, adding the prepared RF resin solution, controlling the temperature to be 25 ℃, stirring for 20 hours, and continuously adding ammonia water to adjust the pH of the solution to 8-9 to obtain the standard RFL impregnating solution.

Example 1

The formula of the modified RFL impregnating solution comprises, by weight, 100 parts of the RFL impregnating solution, 1.5 parts of the silicon dioxide aerogel surface-modified by the silane coupling agent and 15 parts of absolute ethyl alcohol. The preparation process of the RFL impregnating solution is the same as that of the standard RFL impregnating solution in comparative example 1.

Adding the silica aerogel modified on the surface of the coupling agent into absolute ethyl alcohol, fully dispersing, adding the silica aerogel into a reaction kettle of the RFL impregnating solution, mechanically stirring for 30min at normal temperature, and then carrying out ultrasonic treatment for 10min to uniformly mix the silica aerogel to obtain the modified RFL impregnating solution.

Example 2

The formula of the modified RFL impregnating solution comprises, by weight, 100 parts of the RFL impregnating solution, 2 parts of the silicon dioxide aerogel surface-modified by the silane coupling agent and 20 parts of absolute ethyl alcohol. The preparation process of the RFL impregnating solution is the same as that of the standard RFL impregnating solution in comparative example 1.

Adding the silica aerogel with the surface modified by the coupling agent into absolute ethyl alcohol, fully dispersing, adding the silica aerogel into a reaction kettle containing RFL impregnating solution, mechanically stirring for 30min at normal temperature, and then carrying out ultrasonic treatment for 10min to uniformly mix the silica aerogel to obtain the modified RFL impregnating solution.

Example 3

The formula of the modified RFL impregnating solution comprises, by weight, 100 parts of the RFL impregnating solution, 2.5 parts of the silicon dioxide aerogel surface-modified by the silane coupling agent and 25 parts of absolute ethyl alcohol. The preparation process of the RFL impregnating solution is the same as that of the standard RFL impregnating solution in comparative example 1.

Example 4

The formula of the modified RFL impregnating solution comprises, by weight, 100 parts of the RFL impregnating solution, 1.5 parts of silane coupling agent surface modified silica aerogel (KH 560 modified treatment) and 25 parts of absolute ethyl alcohol. The preparation process of the RFL impregnating solution is the same as that of the standard RFL impregnating solution in comparative example 1.

Comparative example 2

The formula of the modified RFL impregnating solution comprises, by weight, 100 parts of the RFL impregnating solution, 15 parts of the silicon dioxide aerogel surface-modified by the silane coupling agent and 150 parts of absolute ethyl alcohol.

Performance test:

canvas impregnation treatment was performed using the impregnation solutions prepared in examples 1 to 4 and comparative examples 1 to 2, respectively: soaking the polyester fiber canvas with absolute ethyl alcohol for 10min at normal temperature to remove the oiling agent on the surface of the fiber fabric, and then washing with deionized water for three times and drying; immersing the pretreated fiber fabric into the prepared immersion liquid at normal temperature for 2min, and calendaring for 1min; drying the impregnated fiber fabric at 140 ℃ for 10min, and removing water in the fiber fabric; carrying out heat treatment on the dried fiber fabric at 240 ℃ for 2min to obtain a finished product;

peeling test sample bar preparation: the size of the fiber fabric after gum dipping treatment is cut into 25cm multiplied by 25cm, the upper part and the lower part of the fiber fabric are attached through mixed adhesive layer rubber (self-made) with the thickness of 4mm, and the fiber fabric is placed on a flat vulcanizing machine for vulcanization, wherein the vulcanization temperature is 150 ℃, the vulcanization pressure is 15MPa, and the vulcanization time is 40min. After vulcanization, the peel strength was prepared and tested according to GB/T6759-2013 test method for adhesive strength between conveyor belts. FIG. 1 is a photograph of a modified RFL dip strip sample of example 2; FIG. 2 is a photograph of a sample of comparative example 1 standard RFL dip strip; FIG. 3 is a graph showing the peel strength comparison between example 2 and comparative example 1.

The results of the performance of examples 1 to 4 and comparative examples 1 to 2 are shown in Table 1.

Table 1: adhesive Property comparison of samples obtained in examples and comparative examples

	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％

As can be seen from the data of examples 1-4 and comparative example 1 in Table 1, the modified silica aerogel is added into the dipping liquid in each modified RFL dipping system, the preparation process is simple and effective, the adhesive property of the modified RFL dipping system can be improved by about 30% at most compared with the standard RFL dipping liquid, and meanwhile, the production efficiency is not affected. As is evident from examples 1 to 4 and comparative example 2, after adding too much silica aerogel, the dispersibility thereof in RFL impregnation liquid was deteriorated, the aerogel agglomeration phenomenon was serious, and stress concentration was generated, so that the adhesive property was lowered.

The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims

1. The modified RFL impregnating solution is characterized by comprising, by weight, 100 parts of the RFL impregnating solution, 0.5-10 parts of a coupling agent surface modified silica aerogel and 5-100 parts of ethanol.

2. The modified RFL impregnating solution of claim 1, wherein the method for preparing the silica aerogel surface-modified by the coupling agent comprises: mixing a coupling agent with ethanol and water, and carrying out prehydrolysis to obtain a prehydrolysis product; and mixing the prehydrolysis product with the silica aerogel, and then modifying to obtain the silica aerogel with the surface modified by the coupling agent.

3. The modified RFL impregnating solution according to claim 2, wherein the mass ratio of the coupling agent, ethanol and water is (0.01 to 0.3): (10 to 100): (0.01-2); the mass ratio of the silica aerogel to the coupling agent is 1: (0.01-0.3).

4. The modified RFL impregnating solution of claim 2 or 3, wherein the coupling agent is a silane coupling agent.

5. The modified RFL impregnating solution of claim 4, wherein the silane coupling agent is at least one of MTMS, KH550, KH560, KH551, a1120, KH570, KH580, KH602, and KH 791.

6. The modified RFL impregnating solution according to claim 1, wherein the RFL impregnating solution comprises the following preparation raw materials in parts by weight:

7. The method for producing a modified RFL impregnating solution according to any one of claims 1 to 6, comprising the steps of:

8. The method according to claim 7, wherein the mixing modification comprises mechanical stirring for 0.5 to 1 hour and ultrasonic treatment for 0.1 to 1 hour in sequence.

9. Use of the modified RFL impregnating solution according to any one of claims 1 to 6 or the modified RFL impregnating solution prepared by the preparation method according to any one of claims 7 to 8 in the preparation of fiber reinforced rubber composite materials.

10. The use according to claim 9, wherein the method of preparing the fiber reinforced rubber composite comprises the steps of: dipping the fiber canvas by adopting modified RFL dipping liquid, and then compounding the dipped fiber canvas with a rubber matrix;