A method for preparing a silane coupling agent for improving the interfacial bonding of glass fibers with epoxy resins

Abstract

The application relates to the technical field of composite materials, and discloses a preparation method of a silane coupling agent for improving the interface bonding of glass fibers and epoxy resins, which comprises glass fiber pretreatment, silane coupling agent preparation, coupling treatment and post-curing treatment; by introducing surface-modified nano fillers, the nano fillers are coated or grafted in the hydrolysis and condensation process of the silane coupling agent, after being coated on the surface of the glass fibers, the surface roughness can be increased, mechanical interlocking points can be provided, the nano effect can also transfer stress and prevent crack propagation, so that the interface bonding strength of the glass fiber and the epoxy resin composite material and the overall mechanical properties are improved; the glass fibers are ultrasonically immersed in a pretreatment liquid, the surface of the glass fibers is cleaned and activated by the synergistic effect of a surfactant and an organic base in the pretreatment liquid, the uniformity and bonding firmness of the silane coupling agent coating are ensured, and the moisture and heat resistance of the composite material is improved.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, specifically to a method for preparing a silane coupling agent to improve the interfacial bonding between glass fiber and epoxy resin. Background Technology

[0002] Glass fiber is an inorganic non-metallic material that can replace metals and has excellent performance. Unlike the brittleness of ordinary glass, glass fiber exhibits good flexibility due to its slender shape and retains the core characteristics of glass. It is a basic industrial material that combines lightweight, high strength and multiple functions. Epoxy resin is a class of high molecular polymers containing two or more epoxy groups in its molecules. Its skeleton structure is an aliphatic, alicyclic or aromatic organic compound.

[0003] Currently, in the preparation of glass fiber reinforced epoxy resin composites, the interfacial bonding strength is a key bottleneck restricting its overall performance. Conventional silane coupling agent treatment technology often directly uses a single basic silane coupling agent solution to coat the glass fiber. This method is difficult to build a strong and stable transition layer between the fiber and the resin matrix. Due to the failure to perform sufficient cleaning and activation pretreatment on the glass fiber surface, the processing aids, contaminants and weak boundary layers on the surface will affect the effective bonding of the silane coupling agent, resulting in uneven coating and insufficient adhesion.

[0004] Therefore, a method for preparing silane coupling agents to improve the interfacial bonding between glass fiber and epoxy resin is proposed to solve the above problems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing silane coupling agents that improves the interfacial bonding between glass fiber and epoxy resin, thus solving the problems mentioned in the background art that affect the effective bonding of silane coupling agents, leading to uneven coatings and insufficient adhesion.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a silane coupling agent to improve the interfacial bonding between glass fiber and epoxy resin, comprising the following steps: Step 1: Glass fiber pretreatment. Place the glass fiber in the pretreatment solution and perform ultrasonic impregnation. After treatment, remove the glass fiber and perform staged gradient drying. Step 2: Preparation of silane coupling agent. The basic silane coupling agent, deionized water, alcohol solvent and acid catalyst are mixed and hydrolyzed and condensed under an inert atmosphere. Modified nanofiller is added in batches during the reaction. After the reaction is completed, the pH is adjusted to neutral to obtain the modified silane coupling agent solution. Step 3: Coupling treatment. The glass fiber pretreated in Step 1 is immersed in the modified silane coupling agent solution prepared in Step 2, and coated using the dip-coating method. Step 4: Post-curing treatment. The glass fiber treated in Step 3 is placed in a curing device and cured by programmed temperature rise to obtain a glass fiber reinforced material with a silane coupling agent layer on the surface. In step two, the modified nanofiller is prepared by surface modification of inorganic nanofiller with silane coupling agent, and its mass is 5%-20% of the mass of the base silane coupling agent. The solid content of the silane coupling agent solution is 5%-15%.

[0007] Preferably, the pretreatment solution in step one consists of the following components by mass percentage: 0.1%-0.5% surfactant, 0.5%-2% organic base, and the balance being deionized water; The ultrasonic impregnation treatment is performed at a temperature of 40-60℃, with an ultrasonic power of 300-600W and an impregnation time of 30-90 minutes. The staged gradient drying process includes: first drying at 60-80℃ for 20-40 minutes, and then drying at 100-120℃ for 40-60 minutes.

[0008] Preferably, the basic silane coupling agent in step two is one or a mixture of γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and vinyltriethoxysilane.

[0009] Preferably, the specific parameters for the coupling process in step three are as follows: The dipping and lifting method has a lifting speed of 50-200 mm / min, a dipping time of 2-10 minutes, and 1-3 coatings. After each coating, it is pre-dried at 80-100℃ for 5-15 minutes.

[0010] Preferably, the preparation of the silane coupling agent in step two specifically includes: A solution A is obtained by mixing a basic silane coupling agent with an alcohol solvent at a volume ratio of 1:3-5. Deionized water and an acidic catalyst are mixed, wherein the amount of acidic catalyst added is 0.1%-0.5% of the mass of the basic silane coupling agent, to obtain solution B; Under stirring and an inert atmosphere, solution B is slowly added dropwise to solution A. After the addition is complete, the hydrolysis reaction is carried out by stirring at 50-70℃ for 1-3 hours. The modified nanofiller was divided into 3-5 equal parts. Under the condition of heat preservation and stirring, one part was added to the hydrolysis reaction system every 15-30 minutes. After all the parts were added, the condensation reaction was continued at 60-80℃ for 2-4 hours. After the reaction is complete, the reaction system is cooled to room temperature, and the pH of the reaction product is adjusted to 6.5-7.5 using an alkaline neutralizing agent to obtain a modified silane coupling agent solution.

[0011] Preferably, the method for preparing the modified nanofiller includes: The inorganic nanofiller was placed in a muffle furnace and calcined at 300-500℃ for 2-4 hours to remove surface organic impurities, thereby obtaining activated nanofiller. It was then dispersed in anhydrous ethanol to prepare a suspension with a mass fraction of 5%-10%, and ultrasonically dispersed for 30-60 minutes. Add silane coupling agent KH-550 or KH-560 to the above suspension, wherein the mass of the silane coupling agent is 10%-30% of the mass of the activated nanofiller, adjust the pH to 4-5 with acetic acid, and stir and reflux at 60-80°C for 4-8 hours. After the reaction was completed, the solid was separated by centrifugation, washed 2-3 times with anhydrous ethanol, and finally dried in a vacuum drying oven at 80-100℃ for 6-12 hours to obtain the modified nanofiller.

[0012] Preferably, the inorganic nanofiller is at least one of nano-silica, nano-alumina, nano-calcium carbonate, carbon nanotubes, or montmorillonite, with an original particle size of 10-100 nanometers.

[0013] Preferably, the post-curing process in step four is as follows: Heat from room temperature to 80-100℃ at a rate of 2-5℃ / min and hold for 20-40 minutes; then heat to 120-140℃ at a rate of 1-3℃ / min and hold for 60-120 minutes, then allow to cool naturally to room temperature.

[0014] Preferably, in step two, the alcohol solvent is at least one of ethanol, isopropanol, or n-butanol; and the acid catalyst is at least one of glacial acetic acid, hydrochloric acid, or citric acid.

[0015] Preferably, in step two, the mass ratio of the basic silane coupling agent, deionized water, and alcohol solvent is 1:0.8-1.2:4-6; and the amount of modified nanofiller added is 8%-15% of the mass of the basic silane coupling agent.

[0016] Compared with the prior art, the present invention provides a method for preparing a silane coupling agent to improve the interfacial bonding between glass fiber and epoxy resin, which has the following beneficial effects: 1. In this invention, by introducing surface-modified nanofillers, which are coated or grafted during the hydrolysis and condensation of silane coupling agents and then coated onto the surface of glass fibers, not only can the surface roughness be increased and mechanical interlocking points be provided, but the nano-effect can also transfer stress and prevent crack propagation, thereby improving the interfacial bonding strength and overall mechanical properties of the glass fiber and epoxy resin composite material.

[0017] 2. In this invention, glass fibers are ultrasonically impregnated with a pretreatment solution. The surfactants and organic bases in the solution work together to clean and activate the glass fiber surface, removing slurry and impurities that are not conducive to bonding, exposing more silanol groups, which creates conditions for the subsequent chemical bonding of silane coupling agent with the fiber surface, ensuring the uniformity and bonding strength of the silane coupling agent coating, and improving the moisture and heat resistance of the composite material.

[0018] 3. In this invention, by employing a programmed temperature-increasing post-curing treatment, the silane coupling agent coating is allowed to fully complete the condensation reaction, forming a dense and stable structure that forms strong chemical bonds with the glass fiber surface. This allows for strong chemical cross-linking during subsequent lamination with epoxy resin, thereby improving the interfacial stability and heat resistance of the composite material. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1: A method for preparing a silane coupling agent to improve the interfacial bonding between glass fiber and epoxy resin, comprising the following steps: Step 1: Glass fiber pretreatment. Place the glass fiber in the pretreatment solution and perform ultrasonic impregnation. After treatment, remove the glass fiber and perform staged gradient drying. Step 2: Preparation of silane coupling agent. The basic silane coupling agent, deionized water, alcohol solvent and acid catalyst are mixed and hydrolyzed and condensed under an inert atmosphere. Modified nanofiller is added in batches during the reaction. After the reaction is completed, the pH is adjusted to neutral to obtain the modified silane coupling agent solution. Step 3: Coupling treatment. The glass fiber pretreated in Step 1 is immersed in the modified silane coupling agent solution prepared in Step 2, and coated using the dip-coating method. Step 4: Post-curing treatment. The glass fiber treated in Step 3 is placed in a curing device and cured by programmed temperature rise to obtain a glass fiber reinforced material with a silane coupling agent layer on the surface. In step two, the modified nanofiller is prepared by surface modification of inorganic nanofiller with silane coupling agent, and its mass is 5% of the mass of the base silane coupling agent, and the solid content of the silane coupling agent solution is 5%.

[0021] The pretreatment solution in step one consists of the following components by mass percentage: 0.1% surfactant, 0.5% organic base, and the remainder is deionized water; The ultrasonic impregnation treatment was performed at a temperature of 40℃, an ultrasonic power of 300W, and an impregnation time of 30 minutes. The staged gradient drying process includes: first drying at 60°C for 20 minutes, and then drying at 100°C for 40 minutes.

[0022] The basic silane coupling agent in step two is γ-aminopropyltriethoxysilane.

[0023] The specific parameters for the coupling process in step three are as follows: The dipping and lifting method has a lifting speed of 50 mm / min, a dipping time of 2 minutes, and is applied once. After each application, it is pre-dried at 80°C for 5 minutes.

[0024] Step two, the preparation of the silane coupling agent, specifically includes: A solution A is obtained by mixing a basic silane coupling agent with an alcohol solvent at a volume ratio of 1:3. Deionized water and acidic catalyst were mixed, with the amount of acidic catalyst added being 0.1% of the mass of the basic silane coupling agent, to obtain solution B; Under stirring and an inert atmosphere, solution B was slowly added dropwise to solution A. After the addition was complete, the hydrolysis reaction was carried out at 50°C with stirring for 1 hour. The modified nanofiller was divided into 3 equal parts. Under the condition of heat preservation and stirring, one part was added to the hydrolysis reaction system every 15 minutes. After all the parts were added, the condensation reaction was continued at 60°C for 2 hours. After the reaction was completed, the reaction system was cooled to room temperature, and the pH of the reaction product was adjusted to 6.5 using an alkaline neutralizing agent to obtain a modified silane coupling agent solution.

[0025] Methods for preparing modified nanofillers include: The inorganic nanofiller was placed in a muffle furnace and calcined at 300°C for 2 hours to remove surface organic impurities, thereby obtaining activated nanofiller. It was then dispersed in anhydrous ethanol to prepare a suspension with a mass fraction of 5%, and ultrasonically dispersed for 30 minutes. Add silane coupling agent KH-550 to the above suspension. The mass of the silane coupling agent is 10% of the mass of the activated nanofiller. Adjust the pH to 4 with acetic acid and stir and reflux at 60°C for 4 hours. After the reaction was completed, the solid was separated by centrifugation, washed twice with anhydrous ethanol, and finally dried in a vacuum drying oven at 80°C for 6 hours to obtain the modified nanofiller.

[0026] The inorganic nanofiller is nano-silica with an original particle size of 10 nanometers.

[0027] The post-curing process in step four is as follows: The temperature was increased from room temperature to 80°C at a rate of 2°C / min and held for 20 minutes; then increased to 120°C at a rate of 1°C / min and held for 60 minutes, and then allowed to cool naturally to room temperature.

[0028] In step two, the alcohol solvent is ethanol; the acid catalyst is glacial acetic acid.

[0029] In step two, the mass ratio of the basic silane coupling agent, deionized water, and alcohol solvent is 1:0.8:4; the amount of modified nanofiller added is 8% of the mass of the basic silane coupling agent.

[0030] Example 2: A method for preparing a silane coupling agent to improve the interfacial bonding between glass fiber and epoxy resin, comprising the following steps: Step 1: Glass fiber pretreatment. Place the glass fiber in the pretreatment solution and perform ultrasonic impregnation. After treatment, remove the glass fiber and perform staged gradient drying. Step 2: Preparation of silane coupling agent. The basic silane coupling agent, deionized water, alcohol solvent and acid catalyst are mixed and hydrolyzed and condensed under an inert atmosphere. Modified nanofiller is added in batches during the reaction. After the reaction is completed, the pH is adjusted to neutral to obtain the modified silane coupling agent solution. Step 3: Coupling treatment. The glass fiber pretreated in Step 1 is immersed in the modified silane coupling agent solution prepared in Step 2, and coated using the dip-coating method. Step 4: Post-curing treatment. The glass fiber treated in Step 3 is placed in a curing device and cured by programmed temperature rise to obtain a glass fiber reinforced material with a silane coupling agent layer on the surface. In step two, the basic silane coupling agent is an aminosilane; The modified nanofiller is prepared by surface modification of inorganic nanofiller with silane coupling agent, and its mass is 12% of the mass of the base silane coupling agent. The solid content of the silane coupling agent solution is 10%.

[0031] The pretreatment solution in step one consists of the following components by mass percentage: 0.3% surfactant, 1.2% organic base, and the balance being deionized water; The ultrasonic impregnation treatment was performed at a temperature of 50°C, an ultrasonic power of 450W, and an impregnation time of 60 minutes. The staged gradient drying process includes: first drying at 70°C for 30 minutes, and then drying at 110°C for 50 minutes.

[0032] The basic silane coupling agent in step two is γ-aminopropyltriethoxysilane.

[0033] The specific parameters for the coupling process in step three are as follows: The dipping and lifting method has a lifting speed of 125 mm / min, a dipping time of 6 minutes, and is applied twice. After each application, it is pre-dried at 90°C for 10 minutes.

[0034] Step two, the preparation of the silane coupling agent, specifically includes: A solution A is obtained by mixing a basic silane coupling agent with an alcohol solvent at a volume ratio of 1:4. Deionized water and acidic catalyst were mixed, with the amount of acidic catalyst added being 0.3% of the mass of the basic silane coupling agent, to obtain solution B. Under stirring and an inert atmosphere, solution B was slowly added dropwise to solution A. After the addition was complete, the hydrolysis reaction was carried out at 60°C with stirring for 2 hours. The modified nanofiller was divided into 4 equal parts. Under the condition of heat preservation and stirring, one part was added to the hydrolysis reaction system every 22 minutes. After all the parts were added, the condensation reaction was continued at 70°C for 3 hours. After the reaction was completed, the reaction system was cooled to room temperature, and the pH of the reaction product was adjusted to 7.0 using an alkaline neutralizing agent to obtain a modified silane coupling agent solution.

[0035] Methods for preparing modified nanofillers include: The inorganic nanofiller was placed in a muffle furnace and calcined at 400°C for 3 hours to remove surface organic impurities, thereby obtaining activated nanofiller. It was then dispersed in anhydrous ethanol to prepare a suspension with a mass fraction of 7.5%, and ultrasonically dispersed for 45 minutes. Add silane coupling agent KH-550 to the above suspension. The mass of the silane coupling agent is 20% of the mass of the activated nanofiller. Adjust the pH to 4.5 with acetic acid and stir and reflux at 70°C for 6 hours. After the reaction was completed, the solid was separated by centrifugation, washed three times with anhydrous ethanol, and finally dried in a vacuum drying oven at 90°C for 9 hours to obtain the modified nanofiller.

[0036] The inorganic nanofiller is nano-silica with an original particle size of 55 nanometers.

[0037] The post-curing process in step four is as follows: The temperature was increased from room temperature to 90°C at a rate of 3.5°C / min and held for 30 minutes; then increased to 130°C at a rate of 2°C / min and held for 90 minutes, followed by natural cooling to room temperature.

[0038] In step two, the alcohol solvent is ethanol; the acid catalyst is glacial acetic acid.

[0039] In step two, the mass ratio of the basic silane coupling agent, deionized water, and alcohol solvent is 1:1.0:5; the amount of modified nanofiller added is 12% of the mass of the basic silane coupling agent.

[0040] Example 3: A method for preparing a silane coupling agent to improve the interfacial bonding between glass fiber and epoxy resin, comprising the following steps: Step 1: Glass fiber pretreatment. Place the glass fiber in the pretreatment solution and perform ultrasonic impregnation. After treatment, remove the glass fiber and perform staged gradient drying. Step 2: Preparation of silane coupling agent. The basic silane coupling agent, deionized water, alcohol solvent and acid catalyst are mixed and hydrolyzed and condensed under an inert atmosphere. Modified nanofiller is added in batches during the reaction. After the reaction is completed, the pH is adjusted to neutral to obtain the modified silane coupling agent solution. Step 3: Coupling treatment. The glass fiber pretreated in Step 1 is immersed in the modified silane coupling agent solution prepared in Step 2, and coated using the dip-coating method. Step 4: Post-curing treatment. The glass fiber treated in Step 3 is placed in a curing device and cured by programmed temperature rise to obtain a glass fiber reinforced material with a silane coupling agent layer on the surface. In step two, the basic silane coupling agent is an aminosilane; The modified nanofiller is prepared by surface modification of inorganic nanofiller with silane coupling agent, and its mass is 20% of the mass of the base silane coupling agent. The solid content of the silane coupling agent solution is 15%.

[0041] The pretreatment solution in step one consists of the following components by mass percentage: 0.5% surfactant, 2% organic base, and the remainder is deionized water; The ultrasonic impregnation treatment temperature was 60℃, the ultrasonic power was 600W, and the impregnation time was 90 minutes. The staged gradient drying process includes: first drying at 80°C for 40 minutes, and then drying at 120°C for 60 minutes.

[0042] The basic silane coupling agent in step two is γ-aminopropyltriethoxysilane.

[0043] The specific parameters for the coupling process in step three are as follows: The dipping and lifting method has a lifting speed of 200 mm / min, a dipping time of 10 minutes, and is applied 3 times. After each application, it is pre-dried at 100℃ for 15 minutes.

[0044] Step two, the preparation of the silane coupling agent, specifically includes: A solution A is obtained by mixing a basic silane coupling agent with an alcohol solvent at a volume ratio of 1:5. Deionized water and acidic catalyst were mixed, with the amount of acidic catalyst added being 0.5% of the mass of the basic silane coupling agent, to obtain solution B. Under stirring and an inert atmosphere, solution B was slowly added dropwise to solution A. After the addition was complete, the hydrolysis reaction was carried out at 70°C with stirring for 3 hours. The modified nanofiller was divided into 5 equal parts. Under the condition of heat preservation and stirring, one part was added to the hydrolysis reaction system every 30 minutes. After all the parts were added, the condensation reaction was continued at 80℃ for 4 hours. After the reaction was completed, the reaction system was cooled to room temperature, and the pH of the reaction product was adjusted to 7.5 using an alkaline neutralizing agent to obtain a modified silane coupling agent solution.

[0045] Methods for preparing modified nanofillers include: The inorganic nanofiller was placed in a muffle furnace and calcined at 500°C for 4 hours to remove surface organic impurities, thereby obtaining activated nanofiller. It was then dispersed in anhydrous ethanol to prepare a suspension with a mass fraction of 10%, and ultrasonically dispersed for 60 minutes. Add silane coupling agent KH-550 to the above suspension. The mass of the silane coupling agent is 30% of the mass of the activated nanofiller. Adjust the pH to 5 with acetic acid and stir and reflux at 80°C for 8 hours. After the reaction was completed, the solid was centrifuged and washed three times with anhydrous ethanol. Finally, it was dried in a vacuum drying oven at 100°C for 12 hours to obtain the modified nanofiller.

[0046] The inorganic nanofiller is nano-silica with an original particle size of 100 nanometers.

[0047] The post-curing process in step four is as follows: The temperature was increased from room temperature to 100°C at a rate of 5°C / min and held for 40 minutes; then increased to 140°C at a rate of 3°C / min and held for 120 minutes, and then allowed to cool naturally to room temperature.

[0048] In step two, the alcohol solvent is ethanol; the acid catalyst is glacial acetic acid.

[0049] In step two, the mass ratio of the basic silane coupling agent, deionized water, and alcohol solvent is 1:1.2:6; the amount of modified nanofiller added is 15% of the mass of the basic silane coupling agent.

[0050] Comparative Example 1: The difference between this comparative example and Examples 1-3 is that no modified nanofiller was added in step two when preparing the modified silane coupling agent solution in this comparative example.

[0051] Comparative Example 2 differs from Examples 1-3 in that: in step one, the step of ultrasonically impregnating the glass fiber in the pretreatment solution is omitted, and the glass fiber cloth is only subjected to conventional washing and drying.

[0052] Comparative Example 3 differs from Examples 1-3 in that, in step two, the original inorganic nanofiller, namely nano-silica, which has not been surface-modified by silane coupling agent, is added instead of the nanofiller modified by KH-550.

[0053] Comparative Example 4 differs from Examples 1-3 in that the programmed temperature rise curing step is omitted in step four of this comparative example, and the curing is carried out at a constant temperature of 100°C for 120 minutes.

[0054] The composite material interface properties of the glass fiber reinforced materials with silane coupling agent layers prepared in Examples 1-3 and Comparative Examples 1-4 were tested. The test items and test methods are as follows: Interlaminar shear strength test: The interfacial bonding strength between glass fiber and epoxy resin matrix was evaluated by short beam shear method. For the water absorption test, the sample was soaked in distilled water for 24 hours at room temperature of 25°C, then removed and the surface moisture was wiped off. The percentage increase in mass was then calculated. The bending strength of composite materials is tested using a universal testing machine to evaluate the overall mechanical properties of the composite materials. Dynamic thermomechanical analysis was performed, and the loss modulus, storage modulus and loss factor of the composite material specimens were tested as a function of temperature to evaluate the influence of the interfacial bonding state on the glass transition temperature of the composite material.

[0055] The test data of the glass fiber and epoxy resin composite materials prepared in Examples 1-3 and Comparative Examples 1-4 are recorded in the table below: By comparing and analyzing the data in the table, it can be seen that the glass fiber reinforced materials with silane coupling agent layers prepared by the processes in Examples 1-3 have significantly better performance than the materials prepared by the processes in Comparative Examples 1-4. This indicates that the present invention, by introducing surface-modified nanofillers, allows them to be coated or grafted during the hydrolysis and condensation of the silane coupling agent. After being coated onto the surface of the glass fiber, it not only increases the surface roughness and provides mechanical interlocking points, but its nano-effect can also transfer stress and prevent crack propagation, thereby improving the interfacial bonding strength and overall mechanical properties of the glass fiber and epoxy resin composite material. Furthermore, the glass fiber is pretreated by ultrasonic treatment. Impregnation utilizes the surfactants and organic bases to synergistically clean and activate the glass fiber surface, removing slurry and impurities that hinder bonding, exposing more silanol groups, and creating conditions for subsequent chemical bonding between the silane coupling agent and the fiber surface. This ensures the uniformity and strong bonding of the silane coupling agent coating, improving the composite material's resistance to damp heat. Post-curing with programmed temperature increases allows the silane coupling agent coating to fully complete the condensation reaction, forming a dense and stable structure that forms strong chemical bonds with the glass fiber surface. This facilitates strong chemical cross-linking during subsequent epoxy resin lamination, thereby improving the composite material's interfacial stability and heat resistance.

[0056] By comparing and analyzing the relevant data in the table, it can be seen that the glass fiber reinforced material prepared by the process of this invention, after being combined with epoxy resin, has better interfacial bonding strength, mechanical properties and resistance to damp heat.

[0057] 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. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0058] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a silane coupling agent to improve the interfacial bonding between glass fiber and epoxy resin, characterized in that: Includes the following steps: Step 1: Glass fiber pretreatment. Place the glass fiber in the pretreatment solution and perform ultrasonic impregnation. After treatment, remove the glass fiber and perform staged gradient drying. Step 2: Preparation of silane coupling agent. The basic silane coupling agent, deionized water, alcohol solvent and acid catalyst are mixed and hydrolyzed and condensed under an inert atmosphere. Modified nanofiller is added in batches during the reaction. After the reaction is completed, the pH is adjusted to neutral to obtain the modified silane coupling agent solution. Step 3: Coupling treatment. The glass fiber pretreated in Step 1 is immersed in the modified silane coupling agent solution prepared in Step 2, and coated using the dip-coating method. Step 4: Post-curing treatment. The glass fiber treated in Step 3 is placed in a curing device and cured by programmed temperature rise to obtain a glass fiber reinforced material with a silane coupling agent layer on the surface. In step two, the modified nanofiller is prepared by surface modification of inorganic nanofiller with silane coupling agent, and its mass is 5%-20% of the mass of the base silane coupling agent. The solid content of the silane coupling agent solution is 5%-15%.

2. The method for preparing a silane coupling agent to improve the interfacial bonding between glass fiber and epoxy resin according to claim 1, characterized in that: The pretreatment solution in step one consists of the following components by mass percentage: 0.1%-0.5% surfactant, 0.5%-2% organic base, and the balance being deionized water; The ultrasonic impregnation treatment is performed at a temperature of 40-60℃, with an ultrasonic power of 300-600W and an impregnation time of 30-90 minutes. The staged gradient drying process includes: first drying at 60-80℃ for 20-40 minutes, and then drying at 100-120℃ for 40-60 minutes.

3. The method for preparing a silane coupling agent to improve the interfacial bonding between glass fiber and epoxy resin according to claim 1, characterized in that: The basic silane coupling agent in step two is one or a mixture of γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and vinyltriethoxysilane.

4. The method for preparing a silane coupling agent to improve the interfacial bonding between glass fiber and epoxy resin according to claim 1, characterized in that: The specific parameters for the coupling process in step three are as follows: The dipping and lifting method has a lifting speed of 50-200 mm / min, a dipping time of 2-10 minutes, and 1-3 coatings. After each coating, it is pre-dried at 80-100℃ for 5-15 minutes.

5. The method for preparing a silane coupling agent to improve the interfacial bonding between glass fiber and epoxy resin according to claim 1, characterized in that: The preparation of the silane coupling agent in step two specifically includes: A solution A is obtained by mixing a basic silane coupling agent with an alcohol solvent at a volume ratio of 1:3-5. Deionized water and an acidic catalyst are mixed, wherein the amount of acidic catalyst added is 0.1%-0.5% of the mass of the basic silane coupling agent, to obtain solution B; Under stirring and an inert atmosphere, solution B is slowly added dropwise to solution A. After the addition is complete, the hydrolysis reaction is carried out by stirring at 50-70℃ for 1-3 hours. The modified nanofiller was divided into 3-5 equal parts. Under the condition of heat preservation and stirring, one part was added to the hydrolysis reaction system every 15-30 minutes. After all the parts were added, the condensation reaction was continued at 60-80℃ for 2-4 hours. After the reaction was completed, the reaction system was cooled to room temperature, and the pH of the reaction product was adjusted to 6.5-7.5 using an alkaline neutralizing agent to obtain a modified silane coupling agent solution.

6. The method for preparing a silane coupling agent to improve the interfacial bonding between glass fiber and epoxy resin according to claim 5, characterized in that: The preparation method of the modified nanofiller includes: The inorganic nanofiller was placed in a muffle furnace and calcined at 300-500℃ for 2-4 hours to remove surface organic impurities, thereby obtaining activated nanofiller. It was then dispersed in anhydrous ethanol to prepare a suspension with a mass fraction of 5%-10%, and ultrasonically dispersed for 30-60 minutes. Add silane coupling agent KH-550 or KH-560 to the above suspension, wherein the mass of the silane coupling agent is 10%-30% of the mass of the activated nanofiller, adjust the pH to 4-5 with acetic acid, and stir and reflux at 60-80°C for 4-8 hours. After the reaction was completed, the solid was separated by centrifugation, washed 2-3 times with anhydrous ethanol, and finally dried in a vacuum drying oven at 80-100℃ for 6-12 hours to obtain the modified nanofiller.

7. The method for preparing a silane coupling agent to improve the interfacial bonding between glass fiber and epoxy resin according to claim 6, characterized in that: The inorganic nanofiller is at least one of nano-silica, nano-alumina, nano-calcium carbonate, carbon nanotubes, or montmorillonite, with an original particle size of 10-100 nanometers.

8. The method for preparing a silane coupling agent to improve the interfacial bonding between glass fiber and epoxy resin according to claim 1, characterized in that: The post-curing process in step four is as follows: Heat from room temperature to 80-100℃ at a rate of 2-5℃ / min and hold for 20-40 minutes; then heat to 120-140℃ at a rate of 1-3℃ / min and hold for 60-120 minutes, then allow to cool naturally to room temperature.

9. The method for preparing a silane coupling agent to improve the interfacial bonding between glass fiber and epoxy resin according to claim 1, characterized in that: In step two, the alcohol solvent is at least one of ethanol, isopropanol, or n-butanol; the acid catalyst is at least one of glacial acetic acid, hydrochloric acid, or citric acid.

10. The method for preparing a silane coupling agent to improve the interfacial bonding between glass fiber and epoxy resin according to claim 1, characterized in that: In step two, the mass ratio of the basic silane coupling agent, deionized water, and alcohol solvent is 1:0.8-1.2:4-6; the amount of modified nanofiller added is 8%-15% of the mass of the basic silane coupling agent.

Images