A reinforced sizing for glass fibers and a method for its preparation

Abstract

The application relates to the technical field of glass fiber impregnant, and particularly discloses a reinforced impregnant for glass fibers and a preparation method thereof; the impregnant is composed of a film forming agent, a macromolecular coupling agent, an antistatic agent and a lubricant; the film forming agent is formed by copolymers of ethyl acrylate, methyl methacrylate and methyl methacrylate and deionized water; silane modified nano silicon dioxide is added as a reinforcing material of the film forming agent; and the macromolecular coupling agent is a copolymer of butyl acrylate, styrene and maleic anhydride grafted KH-550 silane coupling agent; the prepared reinforced impregnant for glass fibers has good effects, can enhance the breaking strength of the glass fibers and the binding capacity between the glass fibers and resins.

Description

Technical Field

[0001] This invention relates to the field of glass fiber sizing agent technology, specifically to a reinforcing sizing agent for glass fibers and its preparation method. Background Technology

[0002] Glass fiber is an inorganic fiber formed by drawing mineral raw materials such as quartz sand and alumina after high-temperature melting. Its individual fiber diameter is on the micrometer scale. It possesses advantages such as good insulation, strong heat resistance, and high tensile strength, and is widely used in composite materials to enhance their mechanical properties and corrosion resistance. However, the smooth surface of glass fiber, when directly added to composite materials, results in insufficient bonding strength between it and the resin, making the fiber-resin interface a weak point. Therefore, during production, a sizing agent with organic emulsion or solution as its main component is often coated onto the glass fiber surface. The addition of the sizing agent not only helps to enhance the mechanical interlocking or chemical bonding between the fiber and resin, thereby improving the interfacial bonding strength, but also bundles the individual glass fibers together, facilitating subsequent processing, and improves the surface morphology and lubricates the glass fiber.

[0003] Because sizing agents play a crucial role in the development of the glass fiber industry, many companies have begun in-depth research and development. Although my country's glass fiber production technology has made breakthrough progress, the development of sizing agent technology in my country remains slow due to the confidentiality of the technology. The variety of sizing agents is limited, and the wetting effect is not significant enough. For example, paraffin-based sizing agents still used in my country have been discontinued abroad because they contain harmful chemical components. Therefore, developing new sizing agents is particularly important for promoting the development of sizing agent technology and solving the problems of limited variety and insufficient wetting effect of existing sizing agents. Summary of the Invention

[0004] The purpose of this invention is to provide a reinforcing sizing agent for glass fibers and its preparation method, thereby solving the problem of insufficient sizing agent effect.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A method for preparing a reinforcing sizing agent for glass fibers, the preparation method being as follows:

[0007] A macromolecular coupling agent is mixed with deionized water, and the pH is adjusted to 5-6 with acetic acid. The mixture is stirred at 25-30°C and 100-300 rpm for 1.5-2.5 hours to obtain a coupling agent hydrolysate. A lubricant is mixed with deionized water and stirred until homogeneous to obtain a lubricant solution. An antistatic agent is mixed with deionized water and stirred until homogeneous to obtain an antistatic agent solution. A film-forming agent is mixed with deionized water and stirred until homogeneous to obtain a film-forming agent emulsion. The lubricant solution, antistatic agent solution, coupling agent hydrolysate, and deionized water are added to the film-forming agent emulsion, and the pH is adjusted to 5-6 with acetic acid. The mixture is stirred at 25-30°C and 100-300 rpm for 20-40 minutes to obtain a reinforcing sizing agent for glass fibers.

[0008] As a limitation of the present invention, the amount of each component in the wetting agent, by weight, is: 3-5 parts film-forming agent, 0.5-1.5 parts macromolecular coupling agent, 0.4-0.6 parts lubricant, and 0.1-0.4 parts antistatic agent.

[0009] As a limitation of the present invention, the preparation method of the film-forming agent is as follows:

[0010] After activating the nano-silica at 90-110℃ for 3-5 hours, it is mixed with ethanol and deionized water, stirred evenly, KH-550 silane coupling agent is added, ultrasonically dispersed, pH is adjusted to 4-6 with acetic acid, and reacted at 65-75℃ for 2-4 hours. After the reaction is completed, it is filtered, washed with ethanol and deionized water, and dried to obtain silane-modified nano-silica.

[0011] Benzoyl peroxide and ethanol were mixed and stirred until homogeneous to obtain a benzoyl peroxide ethanol solution. Ethyl acrylate, methyl methacrylate, methacrylic acid and ethanol were mixed and stirred until homogeneous. Benzoyl peroxide ethanol solution and silane-modified nano silica were added under nitrogen as a protective gas at 70-90℃ and 200-300 rpm. The reaction was carried out for 2-4 hours. After the reaction was completed, the mixture was allowed to stand and filtered to obtain a film-forming agent.

[0012] As a limitation of the present invention, the amount of each component in the film-forming agent by weight is: 1.8 to 2.2 parts of nano silica, 0.06 to 0.10 parts of KH-550 silane coupling agent, 50 to 55 parts of ethyl acrylate, 33 to 37 parts of methyl methacrylate, and 10 to 15 parts of methacrylic acid.

[0013] As a limitation of this invention, the preparation method of the macromolecular coupling agent is as follows:

[0014] Butyl acrylate, styrene, toluene, and benzoyl peroxide were mixed and stirred until homogeneous. The mixture was then reacted at 70–90 °C for 0.5–1.5 h under nitrogen as a protective gas. After 0.5–1.5 h, styrene, maleic anhydride, and benzoyl peroxide were added, and the reaction was continued at 70–90 °C for 2–4 h. After the reaction was completed, petroleum ether was added, and the mixture was filtered. The filter residue was dried at 70–90 °C to obtain a butyl acrylate-styrene-maleic anhydride copolymer.

[0015] Under nitrogen as a protective gas, butyl acrylate-styrene-maleic anhydride copolymer, triethylamine and KH-550 silane coupling agent are mixed and stirred evenly. The mixture is reacted at 25-30°C for 20-26 hours. After the reaction is completed, petroleum ether is added, the mixture is filtered, and the filter residue is dried at 50-70°C to obtain the macromolecular coupling agent.

[0016] As a limitation of the present invention, the amount of each component in the macromolecular coupling agent by weight is: 3.0-5.0 parts butyl acrylate, 3.0-5.0 parts styrene, 0.5-1.5 parts maleic anhydride, 0.8-1.2 parts triethylamine, and 0.8-1.2 parts KH-550 silane coupling agent.

[0017] As a limitation of this invention, the method for preparing the antistatic agent is as follows:

[0018] 1-Vinylimidazolium, n-hexane, and 2,6-tert-butyl-4-methylphenol were mixed and stirred until homogeneous. Bromoethane was slowly added under nitrogen as a protective gas. The reaction was carried out at 35–45 °C for 20–26 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed, and dried under vacuum to obtain 1-vinyl-3-ethylimidazolium bromide.

[0019] 1-Vinyl-3-ethylimidazolium bromide and chloroform were mixed and stirred until homogeneous. A large amount of nitrogen gas was introduced as a protective gas, and the mixture was reacted at 50–60 °C for 0.5–1.5 h. After 0.5–1.5 h, azobisisobutyronitrile was added, and the temperature was raised to 60–70 °C. The reaction was continued for 1.5–2.5 h. After the reaction was completed, the temperature was raised to 100–110 °C to distill off the chloroform. Potassium hexafluorophosphate and deionized water were added, and the mixture was stirred thoroughly at 35–45 °C to dissolve. The mixture was then reacted at 30–40 °C for 20–26 h. After the reaction was completed, the mixture was dried under vacuum to obtain the antistatic agent.

[0020] As a limitation of the present invention, the amounts of each component in the antistatic agent, by weight, are: 18.5-19.0 parts of 1-vinylimidazolium, 32.0-34.0 parts of n-hexane, 0.01-0.03 parts of 2,6-tert-butyl-4-methylphenol, 43.0-44.0 parts of bromoethane, 1.2-1.8 parts of azobisisobutyronitrile, and 135-137 parts of potassium hexafluorophosphate.

[0021] As a limitation of the present invention, the lubricant is one or more of stearamide, oleamide, pentaerythritol oleate, and pentaerythritol monostearate.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] Silane-modified nano-silica was added to the film-forming agent. The silane modification can make the nano-silica uniformly dispersed in the film-forming agent. The silane-modified nano-silica added to the film-forming agent can adhere to the oil / water interface and form a network structure through hydrogen bonds, which prevents the movement between emulsion droplets and forms irreversible adsorption, thereby improving the stability of the film-forming agent. After the wetting agent is coated onto the glass fiber, it can not only enhance the surface roughness of the glass fiber, thereby improving the bonding ability between the glass fiber and the resin, but also improve the mechanical properties such as the strength of the glass fiber.

[0024] Coupling agents are an indispensable part of impregnation agents. During the impregnation process, coupling agents play a role in connecting resin groups and inorganic molecules. Compared with silane coupling agents, macromolecular coupling agents synthesized from butyl acrylate-styrene-maleic anhydride copolymer and silane coupling agents have a better connection effect. The alkoxy groups in macromolecular coupling agents can react chemically with glass fibers, and the long organic chains can entangle with the resin, improving the interfacial bonding strength between glass fibers and resin. In addition, after the impregnation agent is coated on the glass fibers, the macromolecular coupling agent has greater steric hindrance, which can significantly improve the surface roughness of the fiber, thereby improving the bonding ability between glass fibers and resin and the mechanical properties of glass fibers such as strength.

[0025] The ionic liquid antistatic agent synthesized from raw materials such as 1-vinylimidazole, bromoethane and potassium hexafluorophosphate not only has certain lubricity and wear resistance, reducing static charge generated by friction, but also has antistatic properties, good thermal stability, and can improve the stability of the wetting agent. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Nano-sized silica (particle size: 15nm), KH-550 silane coupling agent (purity: 98%)

[0028] Example 1: A method for preparing a reinforcing sizing agent for glass fibers, specifically as follows:

[0029] Step 1: Preparation of film-forming agent

[0030] After activating 2.0g of nano-silica at 100℃ for 4h, it was mixed with 10.0g of ethanol and 20.0g of deionized water, stirred evenly, and 0.08g of KH-550 silane coupling agent was added. The mixture was ultrasonically dispersed, and the pH was adjusted to 5 with acetic acid. The mixture was reacted at 70℃ for 3h. After the reaction was completed, the mixture was filtered, washed with ethanol and deionized water, and dried to obtain silane-modified nano-silica.

[0031] 1.0 g of benzoyl peroxide and 20.0 g of ethanol were mixed and stirred until homogeneous to obtain a benzoyl peroxide ethanol solution. 53.0 g of ethyl acrylate, 35.0 g of methyl methacrylate, 12.0 g of methacrylic acid and 40.0 g of ethanol were mixed and stirred until homogeneous. Under nitrogen as a protective gas, the benzoyl peroxide ethanol solution and the obtained silane-modified nano-silica were added at 80 °C and 250 rpm. The reaction was carried out for 3 h. After the reaction was completed, the mixture was allowed to stand and filtered to obtain a film-forming agent.

[0032] Step 2: Preparation of macromolecular coupling agents

[0033] 4.0 g of butyl acrylate, 3.0 g of styrene, 17.32 g of toluene and 0.24 g of benzoyl peroxide were mixed and stirred evenly. The mixture was reacted at 80 °C for 1 h under nitrogen as a protective gas. After 1 h, 1.0 g of styrene, 1.0 g of maleic anhydride and 0.12 g of benzoyl peroxide were added, and the mixture was kept at 80 °C for another 3 h. After the reaction was completed, petroleum ether was added, and the mixture was filtered. The filter residue was dried at 80 °C to obtain the butyl acrylate-styrene-maleic anhydride copolymer.

[0034] Under nitrogen as a protective gas, the obtained butyl acrylate-styrene-maleic anhydride copolymer, 1.0 g of triethylamine and 1.0 g of KH-550 silane coupling agent were mixed and stirred evenly. The mixture was reacted at 25 °C for 24 h. After the reaction was completed, petroleum ether was added, and the mixture was filtered. The filter residue was dried at 60 °C to obtain the macromolecular coupling agent.

[0035] Step 3: Preparation of antistatic agent

[0036] 18.8 g of 1-vinylimidazolium, 33.0 g of n-hexane and 0.02 g of 2,6-tert-butyl-4-methylphenol were mixed and stirred until homogeneous. Under nitrogen as a protective gas, 43.6 g of bromoethane was slowly added and the mixture was reacted at 40 °C for 24 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried under vacuum to obtain 1-vinyl-3-ethylimidazolium bromide.

[0037] The obtained 1-vinyl-3-ethylimidazolium bromide was mixed with 447.6 g of chloroform and stirred evenly. A large amount of nitrogen gas was introduced as a protective gas, and the mixture was reacted at 55 °C for 1 h. After 1 h, 1.5 g of azobisisobutyronitrile was added, the temperature was raised to 65 °C, and the reaction was continued for 2 h. After the reaction was completed, the temperature was raised to 100 °C, the chloroform was distilled off, 136 g of potassium hexafluorophosphate and 100 g of deionized water were added, and the mixture was stirred thoroughly at 40 °C to dissolve. The mixture was then reacted at 35 °C for 24 h. After the reaction was completed, the mixture was dried under vacuum to obtain the antistatic agent.

[0038] Step 4: Preparation of reinforcing sizing agent for glass fibers

[0039] 1.0 g of macromolecular coupling agent and 9 g of deionized water were mixed, and the pH was adjusted to 5 with acetic acid. The mixture was stirred at 25 °C and 200 rpm for 2 h to obtain a coupling agent hydrolysate. 0.5 g of pentaerythritol oleate and 9.5 g of deionized water were mixed and stirred evenly to obtain a lubricant solution. 0.3 g of antistatic agent and 9.7 g of deionized water were mixed and stirred evenly to obtain an antistatic agent solution. 4.0 g of film-forming agent and 36 g of deionized water were mixed and stirred evenly to obtain a film-forming agent emulsion. The lubricant solution, antistatic agent solution, coupling agent hydrolysate, and 30 g of deionized water were added to the film-forming agent emulsion. The pH was adjusted to 5 with acetic acid, and the mixture was stirred at 25 °C and 200 rpm for 30 min to obtain a reinforcing sizing agent for glass fibers.

[0040] Example 2: A method for preparing a reinforcing sizing agent for glass fibers, specifically as follows:

[0041] Step 1: Preparation of film-forming agent

[0042] After activating 2.0g of nano-silica at 100℃ for 4h, it was mixed with 10.0g of ethanol and 20.0g of deionized water, stirred evenly, and 0.08g of KH-550 silane coupling agent was added. The mixture was ultrasonically dispersed, and the pH was adjusted to 5 with acetic acid. The mixture was reacted at 70℃ for 3h. After the reaction was completed, the mixture was filtered, washed with ethanol and deionized water, and dried to obtain silane-modified nano-silica.

[0043] 1.0 g of benzoyl peroxide and 20.0 g of ethanol were mixed and stirred until homogeneous to obtain a benzoyl peroxide ethanol solution. 53.0 g of ethyl acrylate, 35.0 g of methyl methacrylate, 12.0 g of methacrylic acid and 40.0 g of ethanol were mixed and stirred until homogeneous. Under nitrogen as a protective gas, the benzoyl peroxide ethanol solution and the obtained silane-modified nano-silica were added at 80 °C and 250 rpm. The reaction was carried out for 3 h. After the reaction was completed, the mixture was allowed to stand and filtered to obtain a film-forming agent.

[0044] Step 2: Preparation of macromolecular coupling agents

[0045] 4.0 g of butyl acrylate, 3.0 g of styrene, 17.32 g of toluene and 0.24 g of benzoyl peroxide were mixed and stirred evenly. The mixture was reacted at 80 °C for 1 h under nitrogen as a protective gas. After 1 h, 1.0 g of styrene, 1.0 g of maleic anhydride and 0.12 g of benzoyl peroxide were added, and the mixture was kept at 80 °C for another 3 h. After the reaction was completed, petroleum ether was added, and the mixture was filtered. The filter residue was dried at 80 °C to obtain the butyl acrylate-styrene-maleic anhydride copolymer.

[0046] Under nitrogen as a protective gas, the obtained butyl acrylate-styrene-maleic anhydride copolymer, 1.0 g of triethylamine and 1.0 g of KH-550 silane coupling agent were mixed and stirred evenly. The mixture was reacted at 25 °C for 24 h. After the reaction was completed, petroleum ether was added, and the mixture was filtered. The filter residue was dried at 60 °C to obtain the macromolecular coupling agent.

[0047] Step 3: Preparation of antistatic agent

[0048] 18.8 g of 1-vinylimidazolium, 33.0 g of n-hexane and 0.02 g of 2,6-tert-butyl-4-methylphenol were mixed and stirred until homogeneous. Under nitrogen as a protective gas, 43.6 g of bromoethane was slowly added and the mixture was reacted at 40 °C for 24 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried under vacuum to obtain 1-vinyl-3-ethylimidazolium bromide.

[0049] The obtained 1-vinyl-3-ethylimidazolium bromide was mixed with 447.6 g of chloroform and stirred evenly. A large amount of nitrogen gas was introduced as a protective gas, and the mixture was reacted at 55 °C for 1 h. After 1 h, 1.5 g of azobisisobutyronitrile was added, the temperature was raised to 65 °C, and the reaction was continued for 2 h. After the reaction was completed, the temperature was raised to 100 °C, the chloroform was distilled off, 136 g of potassium hexafluorophosphate and 100 g of deionized water were added, and the mixture was stirred thoroughly at 40 °C to dissolve. The mixture was then reacted at 35 °C for 24 h. After the reaction was completed, the mixture was dried under vacuum to obtain the antistatic agent.

[0050] Step 4: Preparation of reinforcing sizing agent for glass fibers

[0051] 0.5 g of macromolecular coupling agent and 9.5 g of deionized water were mixed, and the pH was adjusted to 5 with acetic acid. The mixture was stirred at 25 °C and 200 rpm for 2 h to obtain a coupling agent hydrolysate. 0.4 g of stearamide and 9.6 g of deionized water were mixed and stirred evenly to obtain a lubricant solution. 0.2 g of antistatic agent and 9.8 g of deionized water were mixed and stirred evenly to obtain an antistatic agent solution. 3.0 g of film-forming agent and 37 g of deionized water were mixed and stirred evenly to obtain a film-forming agent emulsion. The lubricant solution, antistatic agent solution, coupling agent hydrolysate, and 30 g of deionized water were added to the film-forming agent emulsion. The pH was adjusted to 5 with acetic acid. The mixture was stirred at 25 °C and 200 rpm for 30 min to obtain a reinforcing sizing agent for glass fibers.

[0052] Example 3: A method for preparing a reinforcing sizing agent for glass fibers, specifically as follows:

[0053] Step 1: Preparation of film-forming agent

[0054] After activating 2.0g of nano-silica at 100℃ for 4h, it was mixed with 10.0g of ethanol and 20.0g of deionized water, stirred evenly, and 0.08g of KH-550 silane coupling agent was added. The mixture was ultrasonically dispersed, and the pH was adjusted to 5 with acetic acid. The mixture was reacted at 70℃ for 3h. After the reaction was completed, the mixture was filtered, washed with ethanol and deionized water, and dried to obtain silane-modified nano-silica.

[0055] 1.0 g of benzoyl peroxide and 20.0 g of ethanol were mixed and stirred until homogeneous to obtain a benzoyl peroxide ethanol solution. 53.0 g of ethyl acrylate, 35.0 g of methyl methacrylate, 12.0 g of methacrylic acid and 40.0 g of ethanol were mixed and stirred until homogeneous. Under nitrogen as a protective gas, the benzoyl peroxide ethanol solution and the obtained silane-modified nano-silica were added at 80 °C and 250 rpm. The reaction was carried out for 3 h. After the reaction was completed, the mixture was allowed to stand and filtered to obtain a film-forming agent.

[0056] Step 2: Preparation of macromolecular coupling agents

[0057] 4.0 g of butyl acrylate, 3.0 g of styrene, 17.32 g of toluene and 0.24 g of benzoyl peroxide were mixed and stirred evenly. The mixture was reacted at 80 °C for 1 h under nitrogen as a protective gas. After 1 h, 1.0 g of styrene, 1.0 g of maleic anhydride and 0.12 g of benzoyl peroxide were added, and the mixture was kept at 80 °C for another 3 h. After the reaction was completed, petroleum ether was added, and the mixture was filtered. The filter residue was dried at 80 °C to obtain the butyl acrylate-styrene-maleic anhydride copolymer.

[0058] Under nitrogen as a protective gas, the obtained butyl acrylate-styrene-maleic anhydride copolymer, 1.0 g of triethylamine and 1.0 g of KH-550 silane coupling agent were mixed and stirred evenly. The mixture was reacted at 25 °C for 24 h. After the reaction was completed, petroleum ether was added, and the mixture was filtered. The filter residue was dried at 60 °C to obtain the macromolecular coupling agent.

[0059] Step 3: Preparation of antistatic agent

[0060] 18.8 g of 1-vinylimidazolium, 33.0 g of n-hexane and 0.02 g of 2,6-tert-butyl-4-methylphenol were mixed and stirred until homogeneous. Under nitrogen as a protective gas, 43.6 g of bromoethane was slowly added and the mixture was reacted at 40 °C for 24 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried under vacuum to obtain 1-vinyl-3-ethylimidazolium bromide.

[0061] The obtained 1-vinyl-3-ethylimidazolium bromide was mixed with 447.6 g of chloroform and stirred evenly. A large amount of nitrogen gas was introduced as a protective gas, and the mixture was reacted at 55 °C for 1 h. After 1 h, 1.5 g of azobisisobutyronitrile was added, the temperature was raised to 65 °C, and the reaction was continued for 2 h. After the reaction was completed, the temperature was raised to 100 °C, the chloroform was distilled off, 136 g of potassium hexafluorophosphate and 100 g of deionized water were added, and the mixture was stirred thoroughly at 40 °C to dissolve. The mixture was then reacted at 35 °C for 24 h. After the reaction was completed, the mixture was dried under vacuum to obtain the antistatic agent.

[0062] Step 4: Preparation of reinforcing sizing agent for glass fibers

[0063] 1.5g of macromolecular coupling agent and 8.5g of deionized water were mixed, and the pH was adjusted to 5 with acetic acid. The mixture was stirred at 25℃ and 200rpm for 2 hours to obtain a coupling agent hydrolysate. 0.6g of oleamide and 9.4g of deionized water were mixed and stirred evenly to obtain a lubricant solution. 0.4g of antistatic agent and 9.6g of deionized water were mixed and stirred evenly to obtain an antistatic agent solution. 5.0g of film-forming agent and 35g of deionized water were mixed and stirred evenly to obtain a film-forming agent emulsion. The lubricant solution, antistatic agent solution, coupling agent hydrolysate, and 30g of deionized water were added to the film-forming agent emulsion. The pH was adjusted to 5 with acetic acid, and the mixture was stirred at 25℃ and 200rpm for 30 minutes to obtain a reinforcing sizing agent for glass fibers.

[0064] Based on Example 1, the following comparative experiments were conducted, specifically Comparative Example 1, Comparative Example 2, and Comparative Example 3, as described below:

[0065] Comparative Example 1: This comparative example relates to a method for preparing a reinforcing sizing agent for glass fibers. The difference from Example 1 is that silane-modified nano-silica is not added to the film-forming agent. Specifically:

[0066] Step 1: Preparation of film-forming agent

[0067] Mix 1.0 g of benzoyl peroxide and 20.0 g of ethanol and stir until homogeneous to obtain a benzoyl peroxide ethanol solution. Mix 53.0 g of ethyl acrylate, 35.0 g of methyl methacrylate, 12.0 g of methacrylic acid and 40.0 g of ethanol and stir until homogeneous. Add the benzoyl peroxide ethanol solution at 80 °C and 250 rpm under nitrogen as a protective gas and react for 3 h. After the reaction is complete, let stand and filter to obtain a film-forming agent.

[0068] Step 2: Preparation of macromolecular coupling agents

[0069] 4.0 g of butyl acrylate, 3.0 g of styrene, 17.32 g of toluene and 0.24 g of benzoyl peroxide were mixed and stirred evenly. The mixture was reacted at 80 °C for 1 h under nitrogen as a protective gas. After 1 h, 1.0 g of styrene, 1.0 g of maleic anhydride and 0.12 g of benzoyl peroxide were added, and the mixture was kept at 80 °C for another 3 h. After the reaction was completed, petroleum ether was added, and the mixture was filtered. The filter residue was dried at 80 °C to obtain the butyl acrylate-styrene-maleic anhydride copolymer.

[0070] Under nitrogen as a protective gas, the obtained butyl acrylate-styrene-maleic anhydride copolymer, 1.0 g of triethylamine and 1.0 g of KH-550 silane coupling agent were mixed and stirred evenly. The mixture was reacted at 25 °C for 24 h. After the reaction was completed, petroleum ether was added, and the mixture was filtered. The filter residue was dried at 60 °C to obtain the macromolecular coupling agent.

[0071] Step 3: Preparation of antistatic agent

[0072] 18.8 g of 1-vinylimidazolium, 33.0 g of n-hexane and 0.02 g of 2,6-tert-butyl-4-methylphenol were mixed and stirred until homogeneous. Under nitrogen as a protective gas, 43.6 g of bromoethane was slowly added and the mixture was reacted at 40 °C for 24 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried under vacuum to obtain 1-vinyl-3-ethylimidazolium bromide.

[0073] The obtained 1-vinyl-3-ethylimidazolium bromide was mixed with 447.6 g of chloroform and stirred evenly. A large amount of nitrogen gas was introduced as a protective gas, and the mixture was reacted at 55 °C for 1 h. After 1 h, 1.5 g of azobisisobutyronitrile was added, the temperature was raised to 65 °C, and the reaction was continued for 2 h. After the reaction was completed, the temperature was raised to 100 °C, the chloroform was distilled off, 136 g of potassium hexafluorophosphate and 100 g of deionized water were added, and the mixture was stirred thoroughly at 40 °C to dissolve. The mixture was then reacted at 35 °C for 24 h. After the reaction was completed, the mixture was dried under vacuum to obtain the antistatic agent.

[0074] Step 4: Preparation of reinforcing sizing agent for glass fibers

[0075] 1.0 g of macromolecular coupling agent and 9 g of deionized water were mixed, and the pH was adjusted to 5 with acetic acid. The mixture was stirred at 25 °C and 200 rpm for 2 h to obtain a coupling agent hydrolysate. 0.5 g of pentaerythritol oleate and 9.5 g of deionized water were mixed and stirred evenly to obtain a lubricant solution. 0.3 g of antistatic agent and 9.7 g of deionized water were mixed and stirred evenly to obtain an antistatic agent solution. 4.0 g of film-forming agent and 36 g of deionized water were mixed and stirred evenly to obtain a film-forming agent emulsion. The lubricant solution, antistatic agent solution, coupling agent hydrolysate, and 30 g of deionized water were added to the film-forming agent emulsion. The pH was adjusted to 5 with acetic acid, and the mixture was stirred at 25 °C and 200 rpm for 30 min to obtain a reinforcing sizing agent for glass fibers.

[0076] Comparative Example 2: This comparative example relates to a method for preparing a reinforcing sizing agent for glass fibers. The difference from Example 1 is that the coupling agent solution added to the sizing agent is an aqueous solution of KH-550 silane coupling agent, specifically:

[0077] Step 1: Preparation of film-forming agent

[0078] After activating 2.0g of nano-silica at 100℃ for 4h, it was mixed with 10.0g of ethanol and 20.0g of deionized water, stirred evenly, and 0.08g of KH-550 silane coupling agent was added. The mixture was ultrasonically dispersed, and the pH was adjusted to 5 with acetic acid. The mixture was reacted at 70℃ for 3h. After the reaction was completed, the mixture was filtered, washed with ethanol and deionized water, and dried to obtain silane-modified nano-silica.

[0079] 1.0 g of benzoyl peroxide and 20.0 g of ethanol were mixed and stirred until homogeneous to obtain a benzoyl peroxide ethanol solution. 53.0 g of ethyl acrylate, 35.0 g of methyl methacrylate, 12.0 g of methacrylic acid and 40.0 g of ethanol were mixed and stirred until homogeneous. Under nitrogen as a protective gas, the benzoyl peroxide ethanol solution and the obtained silane-modified nano-silica were added at 80 °C and 250 rpm. The reaction was carried out for 3 h. After the reaction was completed, the mixture was allowed to stand and filtered to obtain a film-forming agent.

[0080] Step 2: Preparation of antistatic agent

[0081] 18.8 g of 1-vinylimidazolium, 33.0 g of n-hexane and 0.02 g of 2,6-tert-butyl-4-methylphenol were mixed and stirred until homogeneous. Under nitrogen as a protective gas, 43.6 g of bromoethane was slowly added and the mixture was reacted at 40 °C for 24 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried under vacuum to obtain 1-vinyl-3-ethylimidazolium bromide.

[0082] The obtained 1-vinyl-3-ethylimidazolium bromide was mixed with 447.6 g of chloroform and stirred evenly. A large amount of nitrogen gas was introduced as a protective gas, and the mixture was reacted at 55 °C for 1 h. After 1 h, 1.5 g of azobisisobutyronitrile was added, the temperature was raised to 65 °C, and the reaction was continued for 2 h. After the reaction was completed, the temperature was raised to 100 °C, the chloroform was distilled off, 136 g of potassium hexafluorophosphate and 100 g of deionized water were added, and the mixture was stirred thoroughly at 40 °C to dissolve. The mixture was then reacted at 35 °C for 24 h. After the reaction was completed, the mixture was dried under vacuum to obtain the antistatic agent.

[0083] Step 3: Preparation of reinforcing sizing agent for glass fiber

[0084] 1.0 g of silane coupling agent and 9 g of deionized water were mixed, and the pH was adjusted to 5 with acetic acid. The mixture was stirred at 25 °C and 200 rpm for 2 h to obtain a coupling agent hydrolysate. 0.5 g of pentaerythritol oleate and 9.5 g of deionized water were mixed and stirred evenly to obtain a lubricant solution. 0.3 g of antistatic agent and 9.7 g of deionized water were mixed and stirred evenly to obtain an antistatic agent solution. 4.0 g of film-forming agent and 36 g of deionized water were mixed and stirred evenly to obtain a film-forming agent emulsion. The lubricant solution, antistatic agent solution, coupling agent hydrolysate, and 30 g of deionized water were added to the film-forming agent emulsion. The pH was adjusted to 5 with acetic acid, and the mixture was stirred at 25 °C and 200 rpm for 30 min to obtain a reinforcing sizing agent for glass fibers.

[0085] Comparative Example 3: This comparative example relates to a method for preparing a reinforcing sizing agent for glass fibers, which differs from Example 1 in that no antistatic agent is added. Specifically:

[0086] Step 1: Preparation of film-forming agent

[0087] After activating 2.0g of nano-silica at 100℃ for 4h, it was mixed with 10.0g of ethanol and 20.0g of deionized water, stirred evenly, and 0.08g of KH-550 silane coupling agent was added. The mixture was ultrasonically dispersed, and the pH was adjusted to 5 with acetic acid. The mixture was reacted at 70℃ for 3h. After the reaction was completed, the mixture was filtered, washed with ethanol and deionized water, and dried to obtain silane-modified nano-silica.

[0088] 1.0 g of benzoyl peroxide and 20.0 g of ethanol were mixed and stirred until homogeneous to obtain a benzoyl peroxide ethanol solution. 53.0 g of ethyl acrylate, 35.0 g of methyl methacrylate, 12.0 g of methacrylic acid and 40.0 g of ethanol were mixed and stirred until homogeneous. Under nitrogen as a protective gas, the benzoyl peroxide ethanol solution and the obtained silane-modified nano-silica were added at 80 °C and 250 rpm. The reaction was carried out for 3 h. After the reaction was completed, the mixture was allowed to stand and filtered to obtain a film-forming agent.

[0089] Step 2: Preparation of macromolecular coupling agents

[0090] 4.0 g of butyl acrylate, 3.0 g of styrene, 17.32 g of toluene and 0.24 g of benzoyl peroxide were mixed and stirred evenly. The mixture was reacted at 80 °C for 1 h under nitrogen as a protective gas. After 1 h, 1.0 g of styrene, 1.0 g of maleic anhydride and 0.12 g of benzoyl peroxide were added, and the mixture was kept at 80 °C for another 3 h. After the reaction was completed, petroleum ether was added, and the mixture was filtered. The filter residue was dried at 80 °C to obtain the butyl acrylate-styrene-maleic anhydride copolymer.

[0091] Under nitrogen as a protective gas, the obtained butyl acrylate-styrene-maleic anhydride copolymer, 1.0 g of triethylamine and 1.0 g of KH-550 silane coupling agent were mixed and stirred evenly. The mixture was reacted at 25 °C for 24 h. After the reaction was completed, petroleum ether was added, and the mixture was filtered. The filter residue was dried at 60 °C to obtain the macromolecular coupling agent.

[0092] Step 3: Preparation of reinforcing sizing agent for glass fiber

[0093] 1.0 g of macromolecular coupling agent and 9 g of deionized water were mixed, and the pH was adjusted to 5 with acetic acid. The mixture was stirred at 25 °C and 200 rpm for 2 h to obtain a coupling agent hydrolysate. 0.5 g of pentaerythritol oleate and 9.5 g of deionized water were mixed and stirred evenly to obtain a lubricant solution. 4.0 g of film-forming agent and 36 g of deionized water were mixed and stirred evenly to obtain a film-forming agent emulsion. The lubricant solution, coupling agent hydrolysate, and 40 g of deionized water were added to the film-forming agent emulsion, and the pH was adjusted to 5 with acetic acid. The mixture was stirred at 25 °C and 200 rpm for 30 min to obtain a reinforcing sizing agent for glass fibers.

[0094] Testing experiment:

[0095] Reinforcing sizing agents for glass fibers were prepared according to the preparation methods in Examples 1, 2, 3, Comparative Examples 1, 2, and 3, respectively.

[0096] Fracture strength determination:

[0097] Glass fiber monofilaments from the same batch produced by Jushi Group Huaian Co., Ltd. were selected and impregnated with the aforementioned reinforcing sizing agent. These were then bundled into glass fiber bundles (linear density: 300 tex) using a bundler. Tests were conducted according to "Test Methods for Reinforcing Yarns - Part 3: Determination of Breaking Strength and Elongation at Break of Glass Fibers" (GB / T 7690.3-2001). Glass fiber bundles coated with different types of reinforcing sizing agents were selected, and a portion was cut from each bundle as a test specimen (effective length: 300 mm). The test specimen was clamped using a flat pneumatic clamp and subjected to tensile force through a universal testing machine until it broke. The breaking strength of the test specimen was then measured.

[0098] Peel strength test:

[0099] Glass fiber monofilaments from the same batch produced by Jushi Group Huaian Co., Ltd. were selected and impregnated with the aforementioned reinforcing sizing agent. They were then horizontally clamped in a fixture. Epoxy resin (E44) and curing agent diethylenetriamine were mixed at a mass ratio of 10:3. A small amount of epoxy resin mixed with curing agent was applied to the glass fiber monofilaments with a needle tip, allowing it to spontaneously form resin microspheres. The mixture was cured at 60℃ for 4 hours and then at 120℃ for 5 hours to obtain glass fiber monofilament samples connected to resin spheres. The samples were fixed in the fixture of a single fiber strength tester and subjected to tensile tests. The sample length was set to 10 mm and the tensile speed to 2 mm / min. The interfacial shear strength between the fiber and the resin was calculated.

[0100] <![CDATA[Breaking strength 度 ( N / tex )]]> <![CDATA[Interface shear strength 度 ( MPa )]]> Example 1 0.502 16.52 Example 2 0.498 16.10 Example 3 0.504 16.84 Comparative Example 1 0.422 11.75 Comparative Example 2 0.436 12.36 Comparative Example 3 0.467 14.16

[0101] Conclusion: The test data from Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 show that after the glass fiber is coated with the reinforcing sizing agent prepared in Example 1, the breaking strength of the glass fiber bundle and the interfacial shear strength between the glass fiber and the resin are improved. The reinforcing sizing agent for glass fiber prepared in this invention can enhance the breaking strength of the glass fiber and the bonding ability between the glass fiber and the resin.

[0102] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing a reinforcing sizing agent for glass fibers, characterized in that: The preparation method is as follows: A macromolecular coupling agent is mixed with deionized water, and the pH is adjusted to 5-6 with acetic acid. The mixture is stirred at 25-30°C and 100-300 rpm for 1.5-2.5 hours to obtain a coupling agent hydrolysate. A lubricant is mixed with deionized water and stirred until homogeneous to obtain a lubricant solution. An antistatic agent is mixed with deionized water and stirred until homogeneous to obtain an antistatic agent solution. A film-forming agent is mixed with deionized water and stirred until homogeneous to obtain a film-forming agent emulsion. The lubricant solution, antistatic agent solution, coupling agent hydrolysate, and deionized water are added to the film-forming agent emulsion, and the pH is adjusted to 5-6 with acetic acid. The mixture is stirred at 25-30°C and 100-300 rpm for 20-40 minutes to obtain a reinforcing sizing agent for glass fibers.

2. The method for preparing a reinforcing sizing agent for glass fibers according to claim 1, characterized in that: By weight, the amounts of each component in the wetting agent are: 3-5 parts film-forming agent, 0.5-1.5 parts macromolecular coupling agent, 0.4-0.6 parts lubricant, and 0.1-0.4 parts antistatic agent.

3. The method for preparing a reinforcing sizing agent for glass fibers according to claim 1, characterized in that: The preparation method of the film-forming agent is as follows: After activating the nano-silica at 90-110℃ for 3-5 hours, it is mixed with ethanol and deionized water, stirred evenly, KH-550 silane coupling agent is added, ultrasonically dispersed, pH is adjusted to 4-6 with acetic acid, and reacted at 65-75℃ for 2-4 hours. After the reaction is completed, it is filtered, washed with ethanol and deionized water, and dried to obtain silane-modified nano-silica. Benzoyl peroxide and ethanol were mixed and stirred until homogeneous to obtain a benzoyl peroxide ethanol solution. Ethyl acrylate, methyl methacrylate, methacrylic acid and ethanol were mixed and stirred until homogeneous. Benzoyl peroxide ethanol solution and silane-modified nano silica were added under nitrogen as a protective gas at 70-90℃ and 200-300 rpm. The reaction was carried out for 2-4 hours. After the reaction was completed, the mixture was allowed to stand and filtered to obtain a film-forming agent.

4. The method for preparing a reinforcing sizing agent for glass fibers according to claim 3, characterized in that: By weight, the film-forming agent contains the following components: 1.8–2.2 parts nano-silica, 0.06–0.10 parts KH-550 silane coupling agent, 50–55 parts ethyl acrylate, 33–37 parts methyl methacrylate, and 10–15 parts methacrylic acid.

5. The method for preparing a reinforcing sizing agent for glass fibers according to claim 1, characterized in that: The preparation method of macromolecular coupling agents is as follows: Butyl acrylate, styrene, toluene, and benzoyl peroxide were mixed and stirred until homogeneous. The mixture was then reacted at 70–90 °C for 0.5–1.5 h under nitrogen as a protective gas. After 0.5–1.5 h, styrene, maleic anhydride, and benzoyl peroxide were added, and the reaction was continued at 70–90 °C for 2–4 h. After the reaction was completed, petroleum ether was added, and the mixture was filtered. The filter residue was dried at 70–90 °C to obtain a butyl acrylate-styrene-maleic anhydride copolymer. Under nitrogen as a protective gas, butyl acrylate-styrene-maleic anhydride copolymer, triethylamine and KH-550 silane coupling agent are mixed and stirred evenly. The mixture is reacted at 25-30°C for 20-26 hours. After the reaction is completed, petroleum ether is added, the mixture is filtered, and the filter residue is dried at 50-70°C to obtain the macromolecular coupling agent.

6. The method for preparing a reinforcing sizing agent for glass fibers according to claim 5, characterized in that: By weight, the components in the macromolecular coupling agent are: 3.0-5.0 parts butyl acrylate, 3.0-5.0 parts styrene, 0.5-1.5 parts maleic anhydride, 0.8-1.2 parts triethylamine, and 0.8-1.2 parts KH-550 silane coupling agent.

7. The method for preparing a reinforcing sizing agent for glass fibers according to claim 1, characterized in that: The preparation method of the antistatic agent is as follows: 1-Vinylimidazolium, n-hexane, and 2,6-tert-butyl-4-methylphenol were mixed and stirred until homogeneous. Bromoethane was slowly added under nitrogen as a protective gas. The reaction was carried out at 35–45 °C for 20–26 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed, and dried under vacuum to obtain 1-vinyl-3-ethylimidazolium bromide. 1-Vinyl-3-ethylimidazolium bromide and chloroform were mixed and stirred until homogeneous. A large amount of nitrogen gas was introduced as a protective gas, and the mixture was reacted at 50–60 °C for 0.5–1.5 h. After 0.5–1.5 h, azobisisobutyronitrile was added, and the temperature was raised to 60–70 °C. The reaction was continued for 1.5–2.5 h. After the reaction was completed, the temperature was raised to 100–110 °C to distill off the chloroform. Potassium hexafluorophosphate and deionized water were added, and the mixture was stirred thoroughly at 35–45 °C to dissolve. The mixture was then reacted at 30–40 °C for 20–26 h. After the reaction was completed, the mixture was dried under vacuum to obtain the antistatic agent.

8. The method for preparing a reinforcing sizing agent for glass fibers according to claim 7, characterized in that: The amounts of each component in the antistatic agent, by weight, are as follows: 18.5–19.0 ​​parts 1-vinylimidazolium, 32.0–34.0 parts n-hexane, 0.01–0.03 parts 2,6-tert-butyl-4-methylphenol, 43.0–44.0 parts bromoethane, 1.2–1.8 parts azobisisobutyronitrile, and 135–137 parts potassium hexafluorophosphate.

9. The method for preparing a reinforcing sizing agent for glass fibers according to claim 1, characterized in that: The lubricant is one or more of stearamide, oleamide, pentaerythritol oleate, and pentaerythritol monostearate.