A sizing agent for alumina fibers and its preparation method

Abstract

A sizing agent for alumina fibers and its preparation method, belonging to the technical field of sizing agent preparation. By weight, the sizing agent includes 20-30 parts of epoxy resin-modified aqueous polyurethane emulsion, 2 parts of active additives, 5-10 parts of emulsifier, 2-3 parts of preservative, 30-40 parts of deionized water, and several parts of mixed regulators. The present invention uses epoxy resin to modify aqueous polyurethane, and obtains a sizing agent beneficial to sizing alumina fibers by adjusting the ratio of each solvent. The sizing agent makes the sizing film on the surface of alumina fibers compliant. Using this sizing agent to size alumina fibers can improve the mechanical properties and wear resistance of alumina fibers, reduce the wear and breakage of alumina fibers in subsequent textile processing, and thus ensure the stability of subsequent fabric weaving processing. In addition, this sizing agent uses water as a solvent, and has the advantages of being green and pollution-free, good compatibility, and easy modification.

Description

Technical Field

[0001] The present invention belongs to the technical field of sizing agent preparation, and particularly relates to a sizing agent for alumina fibers and a preparation method thereof. Background Art

[0002] Due to its good high-temperature stability, chemical inertness, low thermal conductivity, good insulation, corrosion resistance, mechanical strength and other characteristics, alumina fibers are widely used in the fields of aerospace, energy, chemical industry, electronics, medical treatment and protection. In addition, high-temperature composite materials prepared from alumina fibers usually have better mechanical properties, thermal conductivity and corrosion resistance. Therefore, they are expected to become an alternative material in the high-temperature field and have great development potential. Since alumina fibers belong to ceramic fibers, friction and wear will occur during production, processing and subsequent transportation, generating fuzz, which not only affects the smooth progress of subsequent processes but also reduces the overall performance of alumina fibers. In addition, the preform woven from alumina fibers is constantly subjected to mechanical friction during the weaving process on the loom, and the fiber bundle is prone to repeated friction and other effects, resulting in fuzzing, splitting and even breaking of the alumina fiber bundle. Further, during the warp shedding stage of weaving, the shedding is not clear, resulting in defects in the final fabric, unstable dimensional structure and other states, reducing the comprehensive mechanical properties of the alumina fiber composite material. The sizing process is a method to improve the weaving performance of alumina fibers. By sizing, the wear resistance, bundling property and antistatic property of alumina fibers are improved, the friction coefficient of alumina fibers is reduced, the occurrence amount of fuzz during the processing and application process is reduced, and the performance requirements of alumina fibers for processes such as braiding, laying and winding during the subsequent composite material forming process are met.

[0003] Sizing plays a crucial role in improving the mechanical properties of alumina fibers and is an important part of the production process. Therefore, the research and preparation of sizing agents for alumina fibers and the development of excellent slurry formulations are of great significance. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem of poor weaving performance of alumina fibers, and provide a sizing agent for alumina fibers suitable for industrial application and a preparation method thereof. The sizing agent is prepared by modifying an aqueous polyurethane emulsion with epoxy resin. After sizing the alumina fiber bundle with this sizing agent, an alumina fiber bundle with good film flexibility and friction resistance can be obtained.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A sizing agent for alumina fibers. By weight, the sizing agent comprises 20 - 30 parts of epoxy resin - modified aqueous polyurethane emulsion, 2 parts of active auxiliary agent, 5 - 10 parts of emulsifier, 2 - 3 parts of preservative, 30 - 40 parts of deionized water, and several parts of mixed regulator.

[0007] A preparation method of the above - mentioned sizing agent for alumina fibers, and the method is as follows:

[0008] (1) Prepare epoxy resin - modified aqueous polyurethane emulsion: By weight, take 30 parts of poly (1,4 - butanediol adipate) diol and dry it under vacuum at 90 - 120 °C for 2 - 3 h; after drying, cool it to room temperature, introduce nitrogen, add 15 parts of isophorone diisocyanate, react for 2 h, then add 1 - 2 parts of dibutyltin dilaurate and 1 - 2 parts of 2,2 - dimethylolpropionic acid and react for 2 h, add 2 parts of dibutylamine - toluene solution, place it in an oil bath at 70 - 90 °C, react for 0.5 - 1 h, add 5 parts of acetone, react for 0.5 h, then add 4 - 6 parts of E - 51 epoxy resin, react for 4 - 5 h, wait until the temperature drops to 25 - 30 °C, add 3 - 5 parts of a mixed solution of triethylamine and acetone with a ratio of 3:1, and react for 1 h; cool it to 20 - 25 °C, add 5 - 10 parts of deionized water under high - speed shearing, add 3 - 5 parts of ethylenediamine to chain - extend it for 0.5 h in a stable state of the solution, and finally subject the obtained solution to vacuum distillation to remove acetone to obtain an epoxy resin - modified aqueous polyurethane emulsion;

[0009] (2) Take 2 parts of active auxiliary agent, 5 - 10 parts of emulsifier, and 30 - 40 parts of deionized water, mix them and carry out high - speed shearing emulsification at 1200 r / min for 1 - 2 h;

[0010] (3) Take 20 - 30 parts of the epoxy resin - modified aqueous polyurethane solution in step (1) and add it to (2), place it in an oil bath at 100 °C, react for 3 - 4 h, then cool it to 40 - 50 °C, add 2 - 5 parts of absolute ethanol, 2 - 5 parts of hydrochloric acid, 2 - 3 parts of preservative, 3 parts of polyacrylamide, and 10 - 20 parts of deionized water, and carry out high - speed shearing emulsification at 1200 r / min for 3 h to obtain the sizing agent for alumina fibers.

[0011] The beneficial effects of the present invention compared with the prior art are as follows: The present invention modifies waterborne polyurethane with epoxy resin, and obtains a sizing agent beneficial to sizing alumina fibers by adjusting the ratio of each solvent. The sizing agent makes the sizing film on the surface of alumina fibers compliant. Sizing the alumina fibers with this sizing agent can improve the mechanical properties and wear resistance of the alumina fibers, reduce the wear and breakage of the alumina fibers during subsequent textile processing, and thus ensure the stability of the subsequent fabric weaving process. In addition, this sizing agent uses water as a solvent, and has the advantages of being green and pollution-free, good compatibility, and easy modification. The present invention can effectively improve the bundling property of alumina fiber bundles, and improve the weavability such as the wear resistance and strength and elongation of the fibers. Detailed implementation manners

[0012] The technical solutions of the present invention will be further described below in conjunction with the embodiments, but are not limited thereto. Any modification or equivalent replacement of the technical solutions of the present invention without departing from the spirit scope of the technical solutions of the present invention shall be covered within the protection scope of the present invention.

[0013] Detailed implementation manner one: This implementation manner describes a sizing agent for alumina fibers. By weight, the sizing agent includes 20 - 30 parts of epoxy resin-modified waterborne polyurethane emulsion, 2 parts of active additives, 5 - 10 parts of emulsifier, 2 - 3 parts of preservative, 30 - 40 parts of deionized water, and several parts of mixed regulators.

[0014] Detailed implementation manner two: A sizing agent for alumina fibers as described in detailed implementation manner one. The preparation raw materials of the epoxy resin-modified waterborne polyurethane emulsion include 30 parts of poly (1,4-butylene adipate) glycol, 15 parts of isophorone diisocyanate, 1 - 2 parts of dibutyltin dilaurate, 1 - 2 parts of 2,2-dimethylolpropionic acid, 2 parts of dibutylamine-toluene solution (0.1 mol / L), 5 parts of acetone, 4 - 6 parts of E-51 epoxy resin, 3 - 5 parts of a mixed solution of triethylamine and acetone, 5 - 10 parts of deionized water, and 3 - 5 parts of ethylenediamine.

[0015] Embodiment 3: A sizing agent for alumina fibers as described in Embodiment 1 or 2. The preparation method of the epoxy resin-modified aqueous polyurethane emulsion is as follows: Weigh 30 parts of poly(1,4-butylene adipate) diol and place it in a three-necked flask equipped with a stirring paddle. Vacuum dry it in a vacuum drying oven at 90 - 120 °C for 2 - 3 h. Through vacuum drying, the moisture in poly(1,4-butylene adipate) diol can be effectively removed, reducing the possibility of side reactions, improving the selectivity and purity of the reaction, enhancing the quality and stability of poly(1,4-butylene adipate) diol, and ensuring the successful progress of the subsequent preparation process. After drying, cool it to room temperature, introduce nitrogen, add 15 parts of isophorone diisocyanate, and let it react in the flask for 2 h. Then add 1 - 2 parts of dibutyltin dilaurate and 1 - 2 parts of 2,2-dimethylolpropionic acid and let it react for 2 h. Subsequently, add 2 parts of dibutylamine-toluene solution, place it in an oil bath at 70 - 90 °C, react for 0.5 - 1 h, add 5 parts of acetone, react for 0.5 h, then continue to add 4 - 6 parts of E-51 epoxy resin, react for 4 - 5 h. After the temperature drops to 25 - 30 °C, add 3 - 5 parts of a mixed solution of triethylamine and acetone with a ratio of 3:1 and let it react in the flask for 1 h. Cool it to 20 - 25 °C, add 5 - 10 parts of deionized water under high-speed shearing, add 3 - 5 parts of ethylenediamine to extend the chain for 0.5 h in a stable state of the solution, and finally subject the obtained solution to vacuum distillation to remove acetone.

[0016] In the process of preparing the epoxy resin-modified aqueous polyurethane emulsion, the main reason for removing acetone is that acetone is an organic solvent and is not suitable for existing in the final emulsion product. In the previous chain extension reaction, an appropriate amount of acetone is added to the system, and the main purpose is to reduce the viscosity of the system. In the polymerization reaction, the increase in the viscosity of the system will lead to difficult stirring and have an adverse impact on the operation of subsequent steps. By adding acetone, the viscosity of the system can be effectively reduced, making the reaction proceed more smoothly. After the reaction is completed, the obtained polyurethane system contains acetone. Since acetone is an organic solvent and is not suitable for existing in the final aqueous polyurethane emulsion product, it needs to be removed. This is to ensure that the emulsion product meets the environmental protection requirements and application needs. After removing acetone, the obtained emulsion no longer contains organic solvents and meets the requirements of aqueous polyurethane emulsion.

[0017] Removing acetone is to ensure the quality and environmental friendliness of the final product, as well as to meet the application requirements of aqueous polyurethane emulsion.

[0018] High-speed shearing is a method capable of shearing and dispersing liquids. 1. When preparing an epoxy resin aqueous polyurethane emulsion, through the action of high-speed shearing, deionized water can be evenly dispersed into the polyurethane system. This helps to form fine water droplets and encapsulate them in polyurethane particles, thereby achieving the emulsification effect. 2. High-speed shearing helps to evenly disperse ethylenediamine into the polyurethane system and promotes the reaction between ethylenediamine and isocyanate. This can accelerate the formation of polyurethane and further improve the stability of the emulsion.

[0019] Operation under the stable state of the solution: 1. Ensuring the stability of the solution before operation can guarantee the uniformity and consistency between different operations. If the operation occurs when the emulsion is not stable, it may lead to uneven results, such as the aggregation of water droplets, stratification, or inconsistent emulsion quality. By operating under the stable state, a more consistent and reproducible emulsion product can be obtained. 2. When the emulsion is in a stable state, the water droplets and polyurethane particles have formed a uniformly dispersed system, and there is no obvious mutual aggregation and phase separation between the water droplets. This stable state helps to maintain the uniformity, long-term stability, and service performance of the emulsion. 3. The emulsion under the stable state has a lower viscosity and good fluidity, which is beneficial to the mixing of reactants and the progress of the reaction. This can improve the reaction efficiency and the quality of the product and reduce the occurrence of unnecessary reactions or side reactions.

[0020] Specific Embodiment 4: A sizing agent for alumina fibers described in Specific Embodiment 1, wherein the active auxiliary agent is one or more of calcium sulfate, sodium sulfate, nitric acid, and sulfur trioxide. The active auxiliary agent selected in the present invention can adjust the pH of the solution, and an appropriate pH value can improve the compatibility and bonding performance between the fiber and the sizing agent; catalyze the reaction between the fiber and the epoxy resin-modified aqueous polyurethane emulsion, thereby promoting the curing process of the binder. This reaction can improve the bonding strength and wear resistance between the sizing agent and the fiber.

[0021] Specific Embodiment 5: A sizing agent for alumina fibers described in Specific Embodiment 1, wherein the emulsifier is polyoxyethylene stearate. The main reasons for choosing to use this emulsifier are as follows: 1. Polyoxyethylene stearate has good emulsifying properties and can stably disperse immiscible liquids (such as water and oil) together to form an emulsion. This is very important for the sizing agent because the sizing agent usually consists of aqueous and oily components and requires an emulsifier to ensure their uniform dispersion and stability. 2. Polyoxyethylene stearate is a surfactant and has the property of reducing the surface tension of liquids. This enables the sizing agent to better wet and penetrate the fiber surface, improving the compatibility and bonding performance between the fiber and the sizing agent. 3. Polyoxyethylene stearate can provide good stability and persistence in the emulsifier. It can help the sizing agent maintain a stable state for a long time, preventing separation, precipitation, or emulsion breakage. 4. Polyoxyethylene stearate has good solubility and processability, which is convenient for preparing the sizing agent and is compatible with other components. It can provide fluidity and viscosity adjustment, facilitating the processing and application of the sizing agent.

[0022] Specific Embodiment 6: A sizing agent for alumina fibers described in Specific Embodiment 1, wherein the regulator is 2 - 5 parts of absolute ethanol, 2 - 5 parts of hydrochloric acid, and 3 parts of polyacrylamide. The role of the regulator is to adjust the acidity and alkalinity of the sizing solution to ensure the best fiber wetting and bonding effects.

[0023] Specific Embodiment 7: A sizing agent for alumina fibers described in Specific Embodiment 1, wherein the preservative is vanadium pentoxide. The main reason for choosing to use vanadium pentoxide is that it shows good performance in anti-corrosion and has less impact on the environment. It does not contain organic solvents and will not cause serious environmental pollution problems.

[0024] Specific Embodiment 8: A method for preparing a sizing agent for alumina fibers according to any one of Specific Embodiments 1 to 7, the method being:

[0025] (1) Preparation of epoxy resin modified aqueous polyurethane emulsion: Weigh 30 parts of poly (1,4 - butanediol adipate) diol by weight and place it in a three - necked flask equipped with a stirring paddle. Vacuum - dry it in a vacuum drying oven at 90 - 120 °C for 2 - 3 h. Vacuum drying can effectively remove the moisture in poly (1,4 - butanediol adipate) diol, reduce the possibility of side reactions, improve the selectivity and purity of the reaction, enhance the quality and stability of poly (1,4 - butanediol adipate) diol, and ensure the successful progress of the subsequent preparation process. After drying, cool it to room temperature, introduce nitrogen, add 15 parts of isophorone diisocyanate. After it reacts in the flask for 2 h, add 1 - 2 parts of dibutyltin dilaurate and 1 - 2 parts of 2,2 - dimethylolpropionic acid and let it react for 2 h. Then add 2 parts of dibutylamine - toluene solution, place it in an oil bath at 70 - 90 °C, after reacting for 0.5 - 1 h, add 5 parts of acetone, after reacting for 0.5 h, continue to add 4 - 6 parts of E - 51 epoxy resin, react for 4 - 5 h. After the temperature drops to 25 - 30 °C, add 3 - 5 parts of a mixed solution of triethylamine and acetone with a ratio of 3:1 and let it react in the flask for 1 h. Cool it to 20 - 25 °C, add 5 - 10 parts of deionized water under high - speed shearing, add 3 - 5 parts of ethylenediamine to chain - extend it for 0.5 h in a stable state of the solution. Finally, subject the obtained solution to vacuum distillation to remove acetone, and obtain an epoxy resin - modified aqueous polyurethane emulsion;

[0026] (2) Take 2 parts of active additives, 5 - 10 parts of emulsifier and 30 - 40 parts of deionized water, mix them and place them in a flask, and shear - emulsify them at 1200 r / min for 1 - 2 h;

[0027] (3) Take 20 - 30 parts of the epoxy resin - modified aqueous polyurethane solution in step (1) and add it to the flask in (2). Place it in an oil bath at 100 °C, after reacting for 3 - 4 h, cool it to 40 - 50 °C, add 2 - 5 parts of absolute ethanol, 2 - 5 parts of hydrochloric acid, 2 - 3 parts of preservative, 3 parts of polyacrylamide and 10 - 20 parts of deionized water, and shear - emulsify them at 1200 r / min for 3 h to obtain an alumina fiber sizing agent. Except as otherwise specified, the raw materials involved in the present invention can be obtained through market purchase.

[0028] Example 1:

[0029] Preparation of Epoxy Resin Modified Waterborne Polyurethane Emulsion: By weight, 30 parts of poly(1,4-butylene adipate) diol are placed in a three-necked flask equipped with a stirring paddle and vacuum-dried in a vacuum drying oven at 90 °C for 3 h. After drying, the temperature is lowered to room temperature, nitrogen is introduced, and 15 parts of isophorone diisocyanate are added. After reacting for 2 h in the flask, 1 part of dibutyltin dilaurate and 1 part of 2,2-dimethylolpropionic acid are added and allowed to react for 2 h. Subsequently, 2 parts of dibutylamine-toluene solution are added, and the mixture is placed in an oil bath at 70 °C. After reacting for 1 h, 5 parts of acetone are added. After reacting for 0.5 h, 4 parts of E-51 epoxy resin are added and allowed to react for 4 h. After the temperature is lowered to 30 °C, 3 parts of a mixed solution of triethylamine and acetone with a ratio of 3:1 are added and allowed to react in the flask for 1 h. After the temperature is lowered to 25 °C, 5 parts of deionized water are added under high-speed shearing. When the solution is stable, 3 parts of ethylenediamine are added to carry out chain extension for 0.5 h. Finally, the obtained solution is subjected to vacuum distillation to remove acetone, and an epoxy resin modified waterborne polyurethane emulsion is obtained.

[0030] Preparation of Sizing Agent: First, 2 parts of calcium sulfate, 5 parts of polyoxyethylene stearate, and 30 parts of deionized water are mixed and placed in a flask, and the mixture is emulsified by high-speed shearing at 1200 r / min for 1 h. 20 parts of the epoxy resin modified waterborne polyurethane solution are added to the mixture, and the mixture is placed in an oil bath at 100 °C. After reacting for 3 h, the temperature is lowered to 40 °C, and 2 parts of absolute ethanol, 2 parts of hydrochloric acid, 2 parts of vanadium pentoxide, 3 parts of polyacrylamide, and 10 parts of deionized water are added. The mixture is emulsified by high-speed shearing at 1200 r / min for 3 h to obtain an alumina fiber sizing agent.

[0031] Example 2:

[0032] Preparation of Epoxy Resin Modified Waterborne Polyurethane Emulsion: By weight, 30 parts of poly(1,4-butylene adipate) diol are placed in a three-necked flask equipped with a stirring paddle and vacuum-dried in a vacuum drying oven at 90 °C for 3 h. After drying, the temperature is lowered to room temperature, nitrogen is introduced, and 15 parts of isophorone diisocyanate are added. After reacting for 2 h in the flask, 2 parts of dibutyltin dilaurate and 2 parts of 2,2-dimethylolpropionic acid are added and allowed to react for 2 h. Subsequently, 2 parts of dibutylamine-toluene solution are added, and the mixture is placed in an oil bath at 70 °C. After reacting for 1 h, 5 parts of acetone are added. After reacting for 0.5 h, 5 parts of E-51 epoxy resin are added and allowed to react for 4 h. After the temperature is lowered to 30 °C, 3 parts of a mixed solution of triethylamine and acetone with a ratio of 3:1 are added and allowed to react in the flask for 1 h. After the temperature is lowered to 25 °C, 10 parts of deionized water are added under high-speed shearing. When the solution is stable, 5 parts of ethylenediamine are added to carry out chain extension for 0.5 h. Finally, the obtained solution is subjected to vacuum distillation to remove acetone, and an epoxy resin modified waterborne polyurethane emulsion is obtained.

[0033] Preparation of sizing agent: First, take 2 parts of calcium sulfate, 8 parts of polyoxyethylene stearate, and 30 parts of deionized water, mix them and place them in a flask, and shear and emulsify them at 1200 r / min at high speed for 1.5 h. Take 25 parts of epoxy resin-modified aqueous polyurethane solution and add it to the mixed solution. Place it in an oil bath at 100 °C and react for 4 h. Then cool it down to 50 °C, add 3 parts of absolute ethanol, 3 parts of hydrochloric acid, 2 parts of vanadium pentoxide, 3 parts of polyacrylamide, and 10 parts of deionized water, and shear and emulsify them at 1200 r / min at high speed for 3 h to obtain an alumina fiber sizing agent.

[0034] Example 3:

[0035] Preparation of epoxy resin-modified aqueous polyurethane emulsion: According to the weight parts, place 30 parts of poly(adipic acid-1,4-butanediol)diol in a three-necked flask equipped with a stirring paddle, and vacuum dry it in a vacuum drying oven at 90 °C for 3 h. After drying, cool it down to room temperature, introduce nitrogen, add 15 parts of isophorone diisocyanate, and wait for it to react in the flask for 2 h. Then add 2 parts of dibutyltin dilaurate and 2 parts of 2,2-dimethylolpropionic acid and make it react for 2 h. Subsequently, add 2 parts of di-n-butylamine-toluene solution, place it in an oil bath at 70 °C, react for 1 h, add 5 parts of acetone, react for 0.5 h, and then continue to add 6 parts of E-51 epoxy resin and make it react for 4 h. After the temperature drops to 30 °C, add 5 parts of a mixed solution of triethylamine and acetone with a ratio of 3:1 and make it react in the flask for 1 h. After cooling down to 25 °C, add 10 parts of deionized water under high-speed shearing, and add 5 parts of ethylenediamine to make it chain-extend for 0.5 h in a stable state of the solution. Finally, distill the obtained solution under reduced pressure to remove acetone to obtain an epoxy resin-modified aqueous polyurethane emulsion.

[0036] Preparation of sizing agent: First, take 2 parts of calcium sulfate, 10 parts of polyoxyethylene stearate, and 40 parts of deionized water, mix them and place them in a flask, and shear and emulsify them at 1200 r / min at high speed for 2 h. Take 30 parts of epoxy resin-modified aqueous polyurethane solution and add it to the mixed solution. Place it in an oil bath at 100 °C and react for 4 h. Then cool it down to 45 °C, add 5 parts of absolute ethanol, 5 parts of hydrochloric acid, 3 parts of vanadium pentoxide, 3 parts of polyacrylamide, and 15 parts of deionized water, and shear and emulsify them at 1200 r / min at high speed for 3 h to obtain an alumina fiber sizing agent.

[0037] Comparative Example 1:

[0038] Preparation of Epoxy Resin Modified Waterborne Polyurethane Emulsion: By weight, 30 parts of poly(1,4-butylene adipate) diol were placed in a three-necked flask equipped with a stirring paddle and vacuum-dried in a vacuum drying oven at 90 °C for 3 h. After drying, the temperature was lowered to room temperature, nitrogen was introduced, and 15 parts of isophorone diisocyanate were added. After reacting for 2 h in the flask, 1 part of dibutyltin dilaurate and 1 part of 2,2-dimethylolpropionic acid were added and reacted for 2 h. Subsequently, 2 parts of dibutylamine-toluene solution were added, and it was placed in an oil bath at 70 °C. After reacting for 1 h, 5 parts of acetone were added. After reacting for 0.5 h, 2 parts of E-51 epoxy resin were continuously added and reacted for 4 h. After the temperature was lowered to 30 °C, 2 parts of a mixed solution of triethylamine and acetone with a ratio of 3:1 were added and reacted in the flask for 1 h. After cooling to 25 °C, 5 parts of deionized water were added under high-speed shearing. Under the condition of a stable solution, 1 part of ethylenediamine was added for chain extension for 0.5 h. Finally, the obtained solution was distilled under reduced pressure to remove acetone, and an epoxy resin modified waterborne polyurethane emulsion was obtained.

[0039] Preparation of Sizing Agent: First, 2 parts of calcium sulfate, 2 parts of polyoxyethylene stearate, and 20 parts of deionized water were mixed and placed in a flask, and they were emulsified by high-speed shearing at 1200 r / min for 2 h. 10 parts of the epoxy resin modified waterborne polyurethane solution were added to the mixture, and it was placed in an oil bath at 100 °C. After reacting for 4 h, the temperature was lowered to 40 °C, and 2 parts of absolute ethanol, 2 parts of hydrochloric acid, 2 parts of vanadium pentoxide, 3 parts of polyacrylamide, and 15 parts of deionized water were added, and they were emulsified by high-speed shearing at 1200 r / min for 3 h to obtain an alumina fiber sizing agent.

[0040] Comparative Example 2:

[0041] Preparation of Epoxy Resin Modified Waterborne Polyurethane Emulsion: By weight, 30 parts of poly(1,4-butylene adipate) diol were placed in a three-necked flask equipped with a stirring paddle and vacuum-dried in a vacuum drying oven at 90 °C for 3 h. After drying, the temperature was lowered to room temperature, nitrogen was introduced, and 15 parts of isophorone diisocyanate were added. After reacting for 2 h in the flask, 3 parts of dibutyltin dilaurate and 3 parts of 2,2-dimethylolpropionic acid were added and reacted for 2 h. Subsequently, 2 parts of dibutylamine-toluene solution were added, and it was placed in an oil bath at 70 °C. After reacting for 1 h, 5 parts of acetone were added. After reacting for 0.5 h, 10 parts of E-51 epoxy resin were continuously added and reacted for 4 h. After the temperature was lowered to 30 °C, 6 parts of a mixed solution of triethylamine and acetone with a ratio of 3:1 were added and reacted in the flask for 1 h. After cooling to 25 °C, 10 parts of deionized water were added under high-speed shearing. Under the condition of a stable solution, 5 parts of ethylenediamine were added for chain extension for 0.5 h. Finally, the obtained solution was distilled under reduced pressure to remove acetone, and an epoxy resin modified waterborne polyurethane emulsion was obtained.

[0042] Preparation of sizing agent: First, take 2 parts of calcium sulfate, 40 parts of polyoxyethylene stearate, and 30 parts of deionized water, mix them and place them in a flask. Then, shear and emulsify them at a high speed of 1200 r / min for 2 h. Take 45 parts of epoxy resin-modified aqueous polyurethane solution and add it to the mixture. Place it in an oil bath at 100 °C and react for 4 h. After cooling to 40 °C, add 5 parts of absolute ethanol, 5 parts of hydrochloric acid, 3 parts of vanadium pentoxide, 3 parts of polyacrylamide, and 15 parts of deionized water. Shear and emulsify them at a high speed of 1200 r / min for 3 h to obtain the sizing agent for alumina fibers.

[0043] Comparative Example 3:

[0044] Preparation of epoxy resin-modified aqueous polyurethane emulsion: By weight, place 30 parts of poly(adipic acid-1,4-butanediol) diol in a three-necked flask equipped with a stirring paddle, and vacuum dry it in a vacuum drying oven at 90 °C for 3 h. After drying, cool to room temperature, introduce nitrogen, add 15 parts of isophorone diisocyanate, and wait for it to react in the flask for 2 h. Then add 4 parts of dibutyltin dilaurate and 4 parts of 2,2-dimethylolpropionic acid and let it react for 2 h. Subsequently, add 2 parts of di-n-butylamine-toluene solution, place it in an oil bath at 70 °C, react for 1 h, add 5 parts of acetone, react for 0.5 h, and then continue to add 15 parts of E-51 epoxy resin and let it react for 4 h. After the temperature drops to 30 °C, add 5 parts of a mixed solution of triethylamine and acetone with a ratio of 3:1 and let it react in the flask for 1 h. After cooling to 25 °C, add 10 parts of deionized water under high-speed shearing, and add 5 parts of ethylenediamine to chain-extend it for 0.5 h under a stable state of the solution. Finally, distill the obtained solution under reduced pressure to remove acetone to obtain an epoxy resin-modified aqueous polyurethane emulsion.

[0045] Preparation of sizing agent: First, take 2 parts of calcium sulfate, 50 parts of polyoxyethylene stearate, and 40 parts of deionized water, mix them and place them in a flask. Then, shear and emulsify them at a high speed of 1200 r / min for 2 h. Take 50 parts of epoxy resin-modified aqueous polyurethane solution and add it to the mixture. Place it in an oil bath at 100 °C and react for 4 h. After cooling to 40 °C, add 5 parts of absolute ethanol, 5 parts of hydrochloric acid, 3 parts of vanadium pentoxide, 3 parts of polyacrylamide, and 15 parts of deionized water. Shear and emulsify them at a high speed of 1200 r / min for 3 h to obtain the sizing agent for alumina fibers.

[0046] Use the sizing agents prepared in the examples and comparative examples of the present invention to size alumina fibers on a single yarn machine respectively. Among them, the sizing steps are as follows: The alumina fibers are guided by a yarn guide roller and pass through a sizing bath, a pressure roller, and a drying cylinder in sequence at a sizing rate of 3 m / min, and finally are wound around a winding shaft by a guide roller, where the drying temperature is 120 °C. They are sequentially recorded as Alumina Fiber Examples 1-3 and Comparative Examples 1-3.

[0047] After sizing is completed, 1 m of sized fiber bundles are respectively cut from the alumina fiber Examples 1 to 3 and Comparative Examples 1 to 3, placed in an oven and dried at 100 °C. Then the specimens are respectively placed in three beakers, acetone solution is introduced, and the fibers are completely impregnated. Subsequently, the beakers are placed in an 85 °C oil bath, and the acetone solution is changed every 2 hours for extraction for 10 hours. The specimens are placed in an oven to dry, weighed after cooling, and the sizing rate of the specimens is calculated.

[0048] Table 1 Sizing rate of alumina fiber under different sizing conditions

[0049]

[0050] The tensile properties and wear resistance of the fibers before and after sizing in Examples 1 to 3 are tested using an XQ-2 single fiber strength tester and an electronic yarn abrasion tester, and the test data shown in the following table can be obtained:

[0051]

Claims

1. A sizing agent for alumina fibers, characterized in that: by weight, the sizing agent comprises 20 - 30 parts of epoxy resin modified aqueous polyurethane emulsion, 2 parts of active auxiliary agent, 5 - 10 parts of emulsifier, 2 - 3 parts of preservative, 30 - 40 parts of deionized water, 2 - 5 parts of absolute ethanol, 2 - 5 parts of hydrochloric acid, and 3 parts of polyacrylamide; the active auxiliary agent is one or more of calcium sulfate, sodium sulfate, nitric acid, and sulfur trioxide; The preparation method of the epoxy resin modified aqueous polyurethane emulsion is as follows: Take 30 parts of poly (adipic acid - 1,4 - butanediol ester) diol and vacuum dry it at 90 - 120 °C for 2 - 3 h; after drying, cool it to room temperature, introduce nitrogen, add 15 parts of isophorone diisocyanate, react for 2 h, then add 1 - 2 parts of dibutyltin dilaurate and 1 - 2 parts of 2,2 - dimethylolpropionic acid and react for 2 h. Subsequently, add 2 parts of dibutylamine - toluene solution, place it in an oil bath at 70 - 90 °C, react for 0.5 - 1 h, add 5 parts of acetone, react for 0.5 h, then continue to add 4 - 6 parts of E - 51 epoxy resin and react for 4 - 5 h. After the temperature drops to 25 - 30 °C, add 3 - 5 parts of a mixed solution of triethylamine and acetone with a ratio of 3:1 and react for 1 h; cool it to 20 - 25 °C, add 5 - 10 parts of deionized water under high - speed shearing, add 3 - 5 parts of ethylenediamine to make it chain - extend for 0.5 h in a stable state of the solution, and finally subject the obtained solution to vacuum distillation to remove acetone.

2. A sizing agent for alumina fibers according to claim 1, characterized in that: the emulsifier is polyoxyethylene stearate.

3. A sizing agent for alumina fibers according to claim 1, characterized in that: the preservative is vanadium pentoxide.

4. A preparation method of the sizing agent for alumina fibers according to any one of claims 1 - 3, characterized in that: the method is as follows: (1) Prepare epoxy resin modified aqueous polyurethane emulsion: According to the weight parts, take 30 parts of poly (adipic acid - 1,4 - butanediol ester) diol and vacuum dry it at 90 - 120 °C for 2 - 3 h; after drying, cool it to room temperature, introduce nitrogen, add 15 parts of isophorone diisocyanate, react for 2 h, then add 1 - 2 parts of dibutyltin dilaurate and 1 - 2 parts of 2,2 - dimethylolpropionic acid and react for 2 h. Add 2 parts of dibutylamine - toluene solution, place it in an oil bath at 70 - 90 °C, react for 0.5 - 1 h, add 5 parts of acetone, react for 0.5 h, then add 4 - 6 parts of E - 51 epoxy resin and react for 4 - 5 h. After the temperature drops to 25 - 30 °C, add 3 - 5 parts of a mixed solution of triethylamine and acetone with a ratio of 3:1 and react for 1 h; cool it to 20 - 25 °C, add 5 - 10 parts of deionized water under high - speed shearing, add 3 - 5 parts of ethylenediamine to make it chain - extend for 0.5 h in a stable state of the solution, subject the obtained solution to vacuum distillation to remove acetone, and obtain epoxy resin modified aqueous polyurethane emulsion; (2) Take 2 parts of active additives, 5 - 10 parts of emulsifier, and 30 - 40 parts of deionized water, mix them, and perform high-speed shear emulsification at 1200 r / min for 1 - 2 h; (3) Take 20 - 30 parts of the epoxy resin-modified aqueous polyurethane solution from step (1) and add it to (2). Place it in an oil bath at 100 °C. After reacting for 3 - 4 h, cool it down to 40 - 50 °C, add 2 - 5 parts of absolute ethanol, 2 - 5 parts of hydrochloric acid, 2 - 3 parts of preservative, 3 parts of polyacrylamide, and 10 - 20 parts of deionized water, and perform high-speed shear emulsification at 1200 r / min for 3 h to obtain the sizing agent for alumina fibers.

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