A sizing agent, its preparation method and application

Abstract

This invention provides a sizing agent, its preparation method, and its application. The sizing agent provided by this invention comprises a main resin, excipients, and water. The main resin includes fluorescein-based waterborne polyurethane, waterborne polyurethane, and epoxy resin. The excipients include plasticizers and surfactants. This sizing agent exhibits moderate sizing amount (0.6–1.5%), low saturated water absorption (<0.1%), moderate interlaminar shear strength (70–100 MPa), controllable particle size (200–500 nm), and good stability (>6 months).

Description

Technical Field

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

[0002] Carbon fiber is an inorganic high-performance fiber, composed of over 90% carbon by weight, transformed from organic fibers through heat treatment. Carbon fiber reinforced polymer (CFRP) composites are made using carbon fiber or fiber fabric as reinforcement and resin, ceramic, metal, or rubber as the matrix. Carbon fiber can be combined with polyurethane to prepare carbon fiber / polyurethane composites. Carbon fiber possesses high specific strength, high specific modulus, and high temperature resistance, significantly improving the mechanical and heat resistance properties of composites. Polyurethane is a material between rubber and plastic, possessing high mechanical strength, high wear resistance, and good elasticity, and is commonly used in furniture, transportation, and home appliances. Fluorescent waterborne polyurethane has become a research hotspot in recent years. By chemically introducing fluorescent molecules with luminescent properties onto the backbone of waterborne polyurethane, problems such as low fluorescence stability, fluorescence quenching, and high thermal mobility caused by direct physical blending of waterborne polyurethane and fluorescent molecules can be avoided.

[0003] Patent CN110330622A discloses a fluorescent waterborne polyurethane and its preparation method. The patent describes reacting fluorescein with diisocyanate, oligomeric diol, and a hydrophilic chain extender to obtain fluorescent polyurethane. This method avoids the difficulty of obtaining small fluorescein molecules due to the large molecular weight of polyurethane, and the chromophore content of the polyurethane molecule can be adjusted by changing the amount of fluorescein added. Currently, there is a lack of carbon fiber sizing agents designed with fluorescent polyurethane on the market. Such sizing agents can act as an interface layer between carbon fiber and fluorescent polyurethane, and can also be used alone to impart fluorescent properties to carbon fiber. Therefore, fluorescent polyurethane carbon fiber sizing agents have good application prospects.

[0004] The raw materials for carbon fiber reinforced composites include thermosetting and thermoplastic resins. Epoxy resin is a commonly used thermosetting resin matrix, and due to its excellent mechanical properties, insulation, and stability, it has become a commonly used raw material for carbon fiber sizing agents. Currently, sizing agents mostly use epoxy resin as a raw material, and epoxy resin and waterborne polyurethane are often combined to prepare sizing agents.

[0005] Patent CN109403042A discloses a water-based carbon fiber sizing agent. The patent involves preparing an epoxy resin solution, then adding a hydrophilic emulsifier, a water-based wetting and dispersing agent, deionized water, and a solvent-dissolved initiator. Finally, a thickener diluted with deionized water is added, and the mixture is stirred until an emulsion is formed. This method combines epoxy resin and waterborne polyurethane to prepare an emulsion, exhibiting good applicability and can be used in the preparation of waterborne polyurethane / epoxy resin sizing agents. Summary of the Invention

[0006] In view of the problems existing in the prior art, one of the objectives of this invention is to provide an application of fluorescein-based waterborne polyurethane in sizing agents. The inventors of this application have discovered that fluorescein-based waterborne polyurethane has excellent affinity properties in sizing agents and can effectively improve the processing performance of carbon fibers.

[0007] The second objective of this invention is to provide a sizing agent corresponding to the first objective.

[0008] A third objective of this invention is to provide a method for preparing a sizing agent corresponding to the above-mentioned objective.

[0009] The fourth objective of this invention is to provide an application of a sizing agent corresponding to the above-mentioned objective.

[0010] The fifth objective of this invention is to provide a carbon fiber sizing method corresponding to the above-mentioned objective.

[0011] The sixth objective of this invention is to provide a carbon fiber material corresponding to the above-mentioned objective.

[0012] To achieve one of the above objectives, the technical solution adopted by the present invention is as follows:

[0013] An application of a fluorescein-based waterborne polyurethane in a sizing agent, wherein the general structural formula of the fluorescein-based waterborne polyurethane is shown in formula (1):

[0014]

[0015] In formula (1), m is 1 to 10; n is 1 to 10; o is 1 to 10;

[0016] R1 is

[0017] R2 is

[0018] R3 is -O-CH2-CH2-O-;

[0019] R4 is

[0020] R5 is -SO3 - Na + ;

[0021] R6 is either -H or -SCN;

[0022] R7 is -H, -SCN,

[0023] According to the present invention, in general formula (1), there is no intention to restrict the order of structural units -R3-R2-, -R1-R2- and -R4-R2-. As long as R2 is arranged alternately with R1, R3 and R4, R1, R3 and R4 can be in any order, such as R2-R1-R2-R3-R2-R4-R2, R2-R1-R2-R4-R2-R3-R2, etc.; R5 seals R2.

[0024] In some preferred embodiments of the present invention, fluorescein-based aqueous polyurethane is used as a sizing agent resin component.

[0025] In some preferred embodiments of the present invention, the sizing agent resin component further includes waterborne polyurethane and epoxy resin.

[0026] According to the present invention, in the context of the present invention, the term "waterborne polyurethane" does not contain structural units derived from fluorescein and is different from fluorescein-based waterborne polyurethane.

[0027] In some preferred embodiments of the present invention, the waterborne polyurethane is selected from at least one of polyether-type waterborne polyurethanes, the polyether-type waterborne polyurethane being prepared by a raw material system comprising polyether and diisocyanate, wherein the polyether is preferably at least one of polypropylene glycol, polyethylene glycol and polytetrahydrofuran, and the diisocyanate is at least one of toluene diisocyanate, terephthalic diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dimethylbiphenyl diisocyanate, dicyclohexylmethane diisocyanate and hexamethylene diisocyanate.

[0028] According to the present invention, the weight-average molecular weight of the polyether is 1000 to 10000.

[0029] According to the present invention, common or even known polyether-type waterborne polyurethanes in the art can be used in this application and achieve the same technical effects. Therefore, the present invention does not intend to impose too many restrictions on the specific types of polyether-type waterborne polyurethanes.

[0030] In some preferred embodiments of the present invention, the epoxy resin is selected from at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin and bisphenol S type epoxy resin.

[0031] According to the present invention, common or even known bisphenol A type epoxy resin, bisphenol F type epoxy resin and bisphenol S type epoxy resin can be used in this application and achieve the same technical effect. Therefore, the present invention does not intend to impose too many restrictions on the specific parameters of these substances, such as epoxy equivalent, viscosity and other parameters.

[0032] In some preferred embodiments of the present invention, the molar ratio of the fluorescein-based waterborne polyurethane to the waterborne polyurethane is (0.0001-10):1, preferably (0.0001-2):1, and more preferably (0.001-1):1.

[0033] In some preferred embodiments of the present invention, the molar ratio of the epoxy resin to the waterborne polyurethane is (1-20):1, preferably (2-10):1, and more preferably (2-4):1.

[0034] To achieve the second objective mentioned above, the technical solution adopted by the present invention is as follows:

[0035] A sizing agent includes a main resin, excipients, and water. The main resin includes fluorescein-based waterborne polyurethane, waterborne polyurethane, and epoxy resin. The excipients include plasticizers and surfactants.

[0036] The general structural formula of fluorescein-based waterborne polyurethane is shown in formula (1):

[0037]

[0038] In formula (1), m is 1 to 10; n is 1 to 10; o is 1 to 10;

[0039] R1 is

[0040] R2 is

[0041] R3 is -O-CH2-CH2-O-;

[0042] R4 is

[0043] R5 is -SO3 - Na + ;

[0044] R6 is either -H or -SCN;

[0045] R7 is -H, -SCN,

[0046] According to the present invention, in general formula (1), there is no intention to restrict the order of structural units -R3-R2-, -R1-R2- and -R4-R2-. As long as R2 is arranged alternately with R1, R3 and R4, R1, R3 and R4 can be in any order, such as R2-R1-R2-R3-R2-R4-R2, R2-R1-R2-R4-R2-R3-R2, etc.; R5 seals R2.

[0047] In some preferred embodiments of the present invention, the waterborne polyurethane is selected from at least one of polyether-type waterborne polyurethanes, the polyether-type waterborne polyurethane being prepared by a raw material system comprising polyether and diisocyanate, wherein the polyether is preferably at least one of polypropylene glycol, polyethylene glycol and polytetrahydrofuran, and the diisocyanate is at least one of toluene diisocyanate, terephthalic diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dimethylbiphenyl diisocyanate, dicyclohexylmethane diisocyanate and hexamethylene diisocyanate.

[0048] According to the present invention, the weight-average molecular weight of the polyether is 1000 to 10000.

[0049] According to the present invention, common or even known polyether-type waterborne polyurethanes in the art can be used in this application and achieve the same technical effects. Therefore, the present invention does not intend to impose too many restrictions on the specific types of polyether-type waterborne polyurethanes.

[0050] In some preferred embodiments of the present invention, the epoxy resin is selected from at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin and bisphenol S type epoxy resin.

[0051] According to the present invention, common or even known bisphenol A type epoxy resin, bisphenol F type epoxy resin and bisphenol S type epoxy resin can be used in this application and achieve the same technical effect. Therefore, the present invention does not intend to impose too many restrictions on the specific parameters of these substances, such as epoxy equivalent, viscosity and other parameters.

[0052] In some preferred embodiments of the present invention, the plasticizer is selected from at least one of dioctyl diacetate, diisononyl phthalate, dioctyl phthalate, and dioctyl sebacate.

[0053] In some preferred embodiments of the present invention, the surfactant is selected from at least one of oleic acid, potassium oleate, sodium oleate, polyoxyethylene castor oil, polyoxyethylene sorbitan palmitate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monopalmitate, and polyoxyethylene monolaurate.

[0054] According to the present invention, polyoxyethylene castor oil, polyoxyethylene sorbitan palmitate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monopalmitate, and polyoxyethylene monolaurate, which are common or even known in the art, can all be used in this application and achieve the same technical effect. Therefore, the present invention does not intend to impose too many restrictions on the specific parameters of these substances, such as the degree of polymerization.

[0055] In some preferred embodiments of the present invention, the molar ratio of the fluorescein waterborne polyurethane to the waterborne polyurethane in the sizing agent is (0.0001-10):1, preferably (0.0001-2):1, and more preferably (0.001-1):1.

[0056] In some preferred embodiments of the present invention, the molar ratio of the epoxy resin to the waterborne polyurethane in the sizing agent is (1-20):1, preferably (2-10):1, and more preferably (2-4):1.

[0057] In some preferred embodiments of the present invention, the content of the plasticizer in the sizing agent is (0.1-5):1, preferably (0.5-2):1, based on the total molar amount of the waterborne polyurethane.

[0058] In some preferred embodiments of the present invention, the content of the surfactant in the sizing agent is (0.1-5):1, preferably (0.5-2):1, based on the molar amount of the waterborne polyurethane.

[0059] In some preferred embodiments of the present invention, the water content in the sizing agent is 50 wt% to 90 wt%, calculated based on the total mass of the sizing agent.

[0060] According to the present invention, the average particle size of the particulates in the sizing agent is 200-500 nm.

[0061] According to the present invention, in the sizing agent, the waterborne polyurethane encapsulates the epoxy resin to form emulsion particles suspended in water.

[0062] To achieve the third objective mentioned above, the technical solution adopted by the present invention is as follows:

[0063] A method for preparing a sizing agent according to any one of the above embodiments includes: mixing the main resin, the auxiliary agent and the water to obtain the sizing agent.

[0064] In some preferred embodiments of the present invention, the method for preparing the sizing agent includes:

[0065] S1. A mixed resin solution is prepared by mixing a solution containing the fluorescein-containing aqueous polyurethane, a solution containing the aqueous polyurethane, and the epoxy resin.

[0066] S2. Mix the mixed resin solution, the auxiliary agent and water to obtain a concentrated sizing agent solution;

[0067] S3. Optionally, the sizing agent concentrate is diluted with water to obtain the sizing agent.

[0068] According to the present invention, the method for preparing the aqueous polyurethane solution containing the fluorescein comprises: adding fluorescein and diisocyanate to a reactor at room temperature and under a nitrogen atmosphere, based on the amount of diisocyanate added, according to a molar ratio of fluorescein to diisocyanate of 0.1:1 to 0.5:1; reacting at 50 to 70°C for 1 to 3 hours; then adding polyether to a reactor at a molar ratio of polyether to diisocyanate of 0.1:1 to 0.5:1; reacting at 70 to 90°C for 1 to 3 hours; cooling to 50 to 70°C; and then adding dimethylolpropionic acid to a reactor at a molar ratio of dimethylolpropionic acid to diisocyanate of 0.1:1 to 0.5:1. Methylpropionic acid is added to the reactor and reacted for 4–8 hours. The temperature is then lowered to 20–30°C. The capping agent is added to the reactor at a molar ratio of 0.4:1 to 0.8:1. After reacting for 0.5–2 hours, ethanol and acetone are added to the reactor at a molar ratio of 2:1 to 8:1 and a molar ratio of acetone to diisocyanate of 10:1 to 30:1. The mixture is stirred for 0.2–1 hours, filtered, and the filter cake is washed 2–3 times with acetone at a molar ratio of 2:1 to 10:1 with diisocyanate. The filtrate is collected to obtain a fluorescein aqueous polyurethane solution.

[0069] According to the present invention, the method for preparing the solution containing the aqueous polyurethane comprises: adding polyether and diisocyanate to a reactor at room temperature and under a nitrogen atmosphere, based on the amount of diisocyanate added and a molar ratio of polyether to diisocyanate of 0.2:1 to 0.6:1; reacting at 70 to 90°C for 1 to 3 hours; cooling to 50 to 70°C; adding dimethylolpropionic acid to the reactor at a molar ratio of dimethylolpropionic acid to diisocyanate of 0.2:1 to 0.6:1; reacting for 4 to 8 hours; and cooling to 20 to 100°C. At 30℃, the capping agent is added to the reactor at a molar ratio of 0.5:1 to 1:1 to the capping agent. After reacting for 0.5 to 2 hours, ethanol and acetone are added to the reactor at a molar ratio of 5:1 to 10:1 to the ethanol and acetone to the acetone, respectively, and the mixture is stirred for 0.2 to 1 hour. The mixture is then filtered, and the filter cake is washed 2 to 3 times with acetone at a molar ratio of 5:1 to 15:1 to the acetone. The filtrate is collected to obtain an aqueous polyurethane solution.

[0070] According to the present invention, steps S2 and S3 include: adding fluorescein waterborne polyurethane, waterborne polyurethane, and epoxy resin to a reactor at 20–30°C, based on the amount of waterborne polyurethane added, according to the molar ratio of fluorescein waterborne polyurethane to waterborne polyurethane being 0.0001:1–2:1 and the molar ratio of epoxy resin to waterborne polyurethane being 0.5:1–20:1, and stirring for 0.2–1 hour; and, based on the amount of waterborne polyurethane added, according to the molar ratio of surfactant to waterborne polyurethane... With a molar ratio of 0.02:1 to 0.5:1, a molar ratio of plasticizer to waterborne polyurethane of 0.02:1 to 0.5:1, and a molar ratio of water to waterborne polyurethane of 500:1 to 2000:1, surfactant, plasticizer, and water are added to a reactor and emulsified at 3000 to 11000 rpm for 0.2 to 2 hours. Acetone and ethanol are removed by vacuum distillation, and the mixture is diluted with water to a solid content of 10% to 50% to obtain a fluorescein waterborne polyurethane sizing agent.

[0071] According to the present invention, the diisocyanate is toluene diisocyanate, terephthalic diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dimethylbiphenyl diisocyanate, dicyclohexylmethane diisocyanate, or hexamethylene diisocyanate, and the polyether is polyethylene glycol, polypropylene glycol, or polytetrahydrofuran, with a molecular weight between 200 and 6000.

[0072] To achieve the fourth objective mentioned above, the technical solution adopted by the present invention is as follows:

[0073] The application of a sizing agent as described in any one of the above embodiments or a sizing agent prepared by any one of the above embodiments as a carbon fiber sizing agent.

[0074] To achieve the fifth objective mentioned above, the technical solution adopted by the present invention is as follows:

[0075] A carbon fiber sizing method includes diluting the sizing agent as described in any one of the above embodiments or the sizing agent prepared according to any one of the above embodiments, preferably diluting it to a solid content of 10wt% to 50wt%, and then sizing the carbon fiber.

[0076] According to the present invention, solid content refers to the total content of substances other than solvent in the solution.

[0077] According to the present invention, carbon fibers can be sized on a carbon fiber production line, then dried at 120-150°C and filaments collected.

[0078] According to the present invention, the amount of sizing agent can be 0.6wt% to 1.5wt%, based on the mass of the carbon fiber to be sized.

[0079] To achieve the sixth objective mentioned above, the technical solution adopted by the present invention is as follows:

[0080] A carbon fiber material includes carbon fibers and a polymer film attached to the carbon fibers, wherein the polymer film is formed on a sizing agent as described in any one of the above embodiments or on a sizing agent prepared according to a preparation method as described in any one of the above embodiments.

[0081] According to the present invention, the carbon fiber material has a moderate sizing amount (0.6-1.5%), low saturated water absorption rate (<0.1%), moderate interlaminar shear strength (70-100MPa), controllable particle size (200-500nm), and good stability (>6 months).

[0082] The sizing agent of this invention exhibits excellent affinity with fluorescent polyurethane and good compatibility with both thermosetting and thermoplastic resin matrices. It simultaneously improves the surface activity of carbon fibers, enhances their mechanical properties, and increases the bond strength between the carbon fibers and the resin matrix. Furthermore, it imparts strong fluorescence, sufficient bundle aggregation, and low sizing adhesion to the carbon fibers. The process of this invention is simple, highly reproducible, and can meet market demand for fluorescent sizing agents.

[0083] More specifically, the beneficial effects of this invention are at least in the following aspects:

[0084] Firstly, the fluorescein-based waterborne polyurethane in the main agent introduces fluorescent groups onto the polyurethane backbone. The fluorescein-based waterborne polyurethane and waterborne polyurethane are blended in proportion, which can reduce the amount of fluorescein used, thereby reducing production costs.

[0085] Secondly, the presence of ammonium salts and hydrophilic end groups gives waterborne polyurethane excellent water solubility. The hardness of the polymer can be adjusted by changing the molecular weight of the raw materials and the copolymerization ratio, thus giving waterborne polyurethane good affinity.

[0086] Thirdly, in addition to waterborne polyurethane, epoxy resin is also used as the main component of the sizing agent, and surfactants and plasticizers are added as auxiliary agents. The epoxy resin, surfactants and plasticizers can be adjusted according to the sizing agent used. Adjusting the molecular weight of the polyether, the type of surfactant and the variety of plasticizer can adjust the particle size of the sizing agent emulsion, thereby improving the performance of the sizing agent. Detailed Implementation

[0087] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited to the following description.

[0088] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0089] The sized carbon fibers were tested for sizing amount, saturated water absorption rate, and interlaminar shear strength (ILSS). The sizing amount test method included: using acetone as a solvent, treating the sized carbon fibers at its reflux temperature, rotary evaporating the extracted acetone solution to obtain resin, weighing the obtained resin, and calculating its weight as a percentage of the weight of the carbon fibers before sizing. The obtained value was the sizing amount. The interlaminar shear strength (ILSS) test was conducted according to JC / T773-2010.

[0090] In this invention, room temperature refers to the indoor temperature during the experiment, which is approximately in the range of 25°C to 35°C.

[0091] In the following embodiments, unless otherwise specified, "%" represents the mass percentage content.

[0092] Example 1

[0093] Under a nitrogen atmosphere at room temperature, 6.96 g of toluene diisocyanate and 20 g of polyethylene glycol (MW2000) were added to a reactor. After reacting at 80°C for 1 hour, the temperature was lowered to 60°C, and 2.68 g of dimethylolpropionic acid was added. After reacting for 5 hours, the temperature was lowered to 25°C, and 2.5 g of sodium bisulfite was added. After reacting for 1 hour, 10 g of ethanol and 50 g of acetone were added, and the mixture was stirred for 0.5 hours. Then, 2.02 g of triethylamine was added, and the mixture was reacted for 1 hour. The mixture was filtered, and the filter cake was washed with 20 g of acetone each time, for a total of 3 washes. The filtrate was collected to obtain 154.16 g of aqueous polyurethane solution.

[0094] Under a nitrogen atmosphere at room temperature, 3.32 g of fluorescein (CAS No. 2321-07-5) and 8.71 g of toluene diisocyanate were added to a reactor. After reacting at 60°C for 2 hours, 20 g of polyethylene glycol (MW2000) was added, and after reacting at 80°C for 1 hour, the temperature was lowered to 60°C, and 2.68 g of dimethylolpropionic acid was added. After reacting for 5 hours, the temperature was lowered to 25°C, and 2.5 g of sodium bisulfite was added. After reacting for 1 hour, 10 g of ethanol and 50 g of acetone were added, and the mixture was stirred for 0.5 hours. Then, 2.02 g of triethylamine was added, and the mixture was reacted for 1 hour. The mixture was filtered, and the filter cake was washed with 20 g of acetone each time, for a total of 3 washes. The filtrate was collected to obtain 159.23 g of fluorescein aqueous polyurethane solution.

[0095] At 25℃, 154.16g of aqueous polyurethane solution, 159.23g of fluorescein aqueous polyurethane solution and 23.8g of bisphenol A epoxy resin (618) were added to a reactor and stirred for 0.5 hours. Then, 4.26g of sodium oleate, 5.19g of dioctyl adipate and 360g of water were added and emulsified at 7000rpm for 1 hour. Acetone and ethanol were removed by vacuum distillation, and the mixture was diluted with water to a solid content of 20% to obtain 533.2g of fluorescein aqueous polyurethane sizing agent.

[0096] The isothiocyanate fluorescein aqueous polyurethane sizing agent prepared in this embodiment was diluted to 1.5% and used for sizing carbon fibers on a carbon fiber production line. The fibers were then dried at 120°C and wound up. The sizing adhesion of the carbon fibers after sizing was 1.2%, the saturated water absorption rate was 0.08%, and the ILSS was 81 MPa.

[0097] Example 2

[0098] Under a nitrogen atmosphere at room temperature, 6.96 g of toluene diisocyanate and 20 g of polyethylene glycol (MW2000) were added to a reactor. After reacting at 80°C for 1 hour, the temperature was lowered to 60°C, and 2.68 g of dimethylolpropionic acid was added. After reacting for 5 hours, the temperature was lowered to 25°C, and 2.5 g of sodium bisulfite was added. After reacting for 1 hour, 10 g of ethanol and 50 g of acetone were added, and the mixture was stirred for 0.5 hours. Then, 2.02 g of triethylamine was added, and the mixture was reacted for 1 hour. The mixture was filtered, and the filter cake was washed with 20 g of acetone each time, for a total of 3 washes. The filtrate was collected to obtain 154.16 g of aqueous polyurethane solution.

[0099] Under a nitrogen atmosphere at room temperature, 3.89 g of fluorescein isothiocyanate (CAS No. 27072-45-3) and 8.71 g of toluene diisocyanate were added to a reactor. After reacting at 60°C for 2 hours, 20 g of polyethylene glycol (MW2000) was added, and after reacting at 80°C for 1 hour, the temperature was lowered to 60°C, and 2.68 g of dimethylolpropionic acid was added. After reacting for 5 hours, the temperature was lowered to 25°C, and 2.5 g of sodium bisulfite was added. After reacting for 1 hour, 10 g of ethanol and 50 g of acetone were added, and the mixture was stirred for 0.5 hours. Then, 2.02 g of triethylamine was added, and the mixture was reacted for 1 hour. The mixture was filtered, and the filter cake was washed with 20 g of acetone each time, for a total of 3 washes. The filtrate was collected to obtain 159.8 g of an aqueous polyurethane solution of fluorescein isothiocyanate.

[0100] At 25℃, 154.16g of aqueous polyurethane solution, 159.8g of fluorescein aqueous polyurethane solution, and 23.8g of bisphenol A epoxy resin (618) were added to a reactor and stirred for 0.5 hours. Then, 4.26g of sodium oleate, 5.19g of dioctyl adipate, and 360g of water were added, and the mixture was emulsified at 7000rpm for 1 hour. Acetone and ethanol were removed by vacuum distillation, and the mixture was diluted with water to a solid content of 20% to obtain 536.05g of fluorescein isothiocyanate aqueous polyurethane sizing agent.

[0101] The aqueous polyurethane sizing agent containing fluorescein isothiocyanate prepared in this embodiment was diluted to 1.5% and used for sizing carbon fibers on a carbon fiber production line. The fibers were then dried at 120°C and wound up. The sizing adhesion of the carbon fibers after sizing was 1.1%, the saturated water absorption rate was 0.07%, and the ILSS was 80 MPa.

[0102] Example 3

[0103] Under a nitrogen atmosphere at room temperature, 8.71 g of toluene diisocyanate and 10 g of polypropylene glycol (MW2000) were added to a reactor. After reacting at 80°C for 1 hour, the temperature was lowered to 60°C, and 3.32 g of fluorescein was added. After reacting for 2 hours, 2.68 g of dimethylolpropionic acid was added. After reacting for 5 hours, the temperature was lowered to 25°C, and 2.5 g of sodium bisulfite was added. After reacting for 1 hour, 10 g of ethanol was added, and the mixture was stirred for 0.5 hours. The ethanol was removed by vacuum distillation, and 50 g of acetone was added. The mixture was filtered, and the filtrate was collected and placed in a reactor. 2.02 g of triethylamine was added to the reactor, and the mixture was reacted for 1 hour to obtain 79.23 g of an aqueous polyurethane solution of fluorescein.

[0104] Under a nitrogen atmosphere at room temperature, 6.96 g of toluene diisocyanate and 10 g of polypropylene glycol (MW2000) were added to a reactor. After reacting at 80°C for 1 hour, the temperature was lowered to 60°C, and 2.68 g of dimethylolpropionic acid was added. After reacting for 5 hours, the temperature was lowered to 25°C, and 2.5 g of sodium bisulfite was added. After reacting for 1 hour, 10 g of ethanol was added, and the mixture was stirred for 0.5 hours. The ethanol was removed by vacuum distillation, and 50 g of acetone was added. The mixture was filtered, and the filtrate was collected and placed in a reactor. 2.02 g of triethylamine was added to the reactor, and the mixture was reacted for 1 hour to obtain 74.16 g of an aqueous polyurethane solution.

[0105] At 25°C, 79.23g of fluorescein aqueous polyurethane solution, 74.16g of aqueous polyurethane solution, and 23.8g of bisphenol A epoxy resin (618) were added to a reactor and stirred for 0.5 hours. Then, 4.26g of sodium oleate, 5.19g of dioctyl adipate, and 360g of water were added. Acetone was removed by vacuum distillation, and the mixture was diluted with water to a solid content of 20%. The mixture was emulsified at 7000 rpm for 1 hour to obtain 433.2g of fluorescein aqueous polyurethane sizing agent.

[0106] The fluorescein-based waterborne polyurethane sizing agent prepared in this embodiment was diluted to 1.5% and used for sizing carbon fibers on a carbon fiber production line. The fibers were then dried at 120°C and wound up. The sizing adhesion of the carbon fibers after sizing was 1.3%, the saturated water absorption rate was 0.06%, and the ILSS was 101 MPa.

[0107] Example 4

[0108] Under a nitrogen atmosphere at room temperature, 8.71 g of toluene diisocyanate and 20 g of polyethylene glycol (MW2000) were added to a reactor. After reacting at 80°C for 1 hour, the temperature was lowered to 60°C, and 3.32 g of fluorescein was added. After reacting for 2 hours, 2.68 g of dimethylolpropionic acid was added. After reacting for 5 hours, the temperature was lowered to 25°C, and 2.09 g of methyl ethyl ketone oxime was added. After reacting for 1 hour, 10 g of ethanol was added, and the mixture was stirred for 0.5 hours. The ethanol was removed by vacuum distillation, and 50 g of acetone was added. The mixture was filtered, and the filtrate was collected and placed in a reactor. 2.02 g of triethylamine was added to the reactor, and the mixture was reacted for 1 hour to obtain 88.82 g of an aqueous polyurethane solution of fluorescein.

[0109] Under a nitrogen atmosphere at room temperature, 6.96 g of toluene diisocyanate and 20 g of polyethylene glycol (MW2000) were added to a reactor. After reacting at 80°C for 1 hour, the temperature was lowered to 60°C, and 2.68 g of dimethylolpropionic acid was added. After reacting for 5 hours, the temperature was lowered to 25°C, and 2.09 g of methyl ethyl ketone oxime was added. After reacting for 1 hour, 10 g of ethanol was added, and the mixture was stirred for 0.5 hours. The ethanol was removed by vacuum distillation, and 50 g of acetone was added. The mixture was filtered, and the filtrate was collected and placed in a reactor. 2.02 g of triethylamine was added to the reactor, and the mixture was reacted for 1 hour to obtain 83.75 g of an aqueous polyurethane solution.

[0110] At 25°C, 88.82g of fluorescein aqueous polyurethane solution, 83.75g of aqueous polyurethane solution, and 23.8g of bisphenol A epoxy resin (618) were added to a reactor and stirred for 0.5 hours. Then, 4.26g of sodium oleate, 5.19g of dioctyl adipate, and 360g of water were added. Acetone was removed by vacuum distillation, and the mixture was diluted with water to a solid content of 20%. The mixture was emulsified at 7000 rpm for 1 hour to obtain 529.1g of fluorescein aqueous polyurethane sizing agent.

[0111] The fluorescein-based waterborne polyurethane sizing agent prepared in this embodiment was diluted to 1.5% and used for sizing carbon fibers on a carbon fiber production line. The fibers were then dried at 120°C and wound up. The sizing adhesion of the carbon fibers after sizing was 1.1%, the saturated water absorption rate was 0.09%, and the ILSS was 82 MPa.

[0112] Example 5

[0113] Under a nitrogen atmosphere at room temperature, 8.71 g of toluene diisocyanate and 20 g of polyethylene glycol (MW2000) were added to a reactor. After reacting at 80°C for 1 hour, the temperature was lowered to 60°C, and 3.32 g of fluorescein was added. After reacting for 2 hours, 2.68 g of dimethylolpropionic acid was added. After reacting for 5 hours, the temperature was lowered to 25°C, and 2.5 g of sodium bisulfite was added. After reacting for 1 hour, 10 g of ethanol was added, and the mixture was stirred for 0.5 hours. The ethanol was removed by vacuum distillation, and 50 g of acetone was added. The mixture was filtered, and the filtrate was collected and placed in a reactor. 0.8 g of sodium hydroxide was added to the reactor, and the mixture was reacted for 1 hour to obtain 88.01 g of an aqueous polyurethane solution of fluorescein.

[0114] Under a nitrogen atmosphere at room temperature, 6.96 g of toluene diisocyanate and 20 g of polyethylene glycol (MW2000) were added to a reactor. After reacting at 80°C for 1 hour, the temperature was lowered to 60°C, and 2.68 g of dimethylolpropionic acid was added. After reacting for 5 hours, the temperature was lowered to 25°C, and 2.5 g of sodium bisulfite was added. After reacting for 1 hour, 10 g of ethanol was added, and the mixture was stirred for 0.5 hours. The ethanol was removed by vacuum distillation, and 50 g of acetone was added. The mixture was filtered, and the filtrate was collected and placed in a reactor. 0.8 g of sodium hydroxide was added to the reactor, and the mixture was reacted for 1 hour to obtain 82.94 g of an aqueous polyurethane solution.

[0115] At 25°C, 88.01g of fluorescein aqueous polyurethane solution, 82.94g of aqueous polyurethane solution and 23.8g of bisphenol A epoxy resin (618) were added to a reactor and stirred for 0.5 hours. Then, 4.26g of sodium oleate, 5.19g of dioctyl adipate and 360g of water were added. Acetone was removed by vacuum distillation. The mixture was diluted with water to a solid content of 20% and emulsified at 7000rpm for 1 hour to obtain 521g of fluorescein aqueous polyurethane sizing agent.

[0116] The fluorescent waterborne polyurethane sizing agent prepared in this embodiment was diluted to 1.5% and used for sizing carbon fibers on a carbon fiber production line. The fibers were then dried at 120°C and wound up. The sizing adhesion of the carbon fibers after sizing was 1.2%, the saturated water absorption rate was 0.08%, and the ILSS was 83 MPa.

[0117] Example 6

[0118] The fluorescein aqueous polyurethane solution and the aqueous polyurethane solution were prepared in accordance with the method described in Example 1.

[0119] At 25°C, 8.92g of fluorescein aqueous polyurethane solution, 84.16g of aqueous polyurethane solution and 14.62g of bisphenol A epoxy resin (618) were added to a reactor and stirred for 0.5 hours. Then, 2.62g of sodium oleate, 3.19g of dioctyl adipate and 360g of water were added. Acetone was removed by vacuum distillation. The mixture was diluted with water to a solid content of 20% and emulsified at 7000rpm for 1 hour to obtain 292.57g of fluorescein aqueous polyurethane sizing agent.

[0120] The isothiocyanate fluorescein aqueous polyurethane sizing agent prepared in this embodiment was diluted to 1.5% and used for sizing carbon fibers on a carbon fiber production line. The fibers were then dried at 120°C and wound up. The sizing adhesion of the carbon fibers after sizing was 1.1%, the saturated water absorption rate was 0.07%, and the ILSS was 90 MPa.

[0121] Example 7

[0122] This embodiment is basically carried out in accordance with the method of Example 1, except that the amount of bisphenol A type epoxy resin (618) used is 11.9g. After the prepared sizing agent is applied to the carbon fiber in the same manner as in Example 1, the sizing adhesion of the carbon fiber after sizing is measured to be 0.9%, the saturated water absorption rate is 0.12%, and the ILSS is 65MPa.

[0123] Comparative Example 1

[0124] Under a nitrogen atmosphere at room temperature, 6.96 g of toluene diisocyanate and 20 g of polyethylene glycol (MW2000) were added to a reactor. After reacting at 80°C for 1 hour, the temperature was lowered to 60°C, and 2.68 g of dimethylolpropionic acid was added. After reacting for 5 hours, the temperature was lowered to 25°C, and 2.5 g of sodium bisulfite was added. After reacting for 1 hour, 10 g of ethanol and 50 g of acetone were added, and the mixture was stirred for 0.5 hours. Then, 2.02 g of triethylamine was added, and the mixture was reacted for 1 hour. The mixture was filtered, and the filter cake was washed with 20 g of acetone each time, for a total of 3 washes. The filtrate was collected to obtain 154.16 g of aqueous polyurethane solution.

[0125] Under a nitrogen atmosphere at room temperature, 3.32 g of fluorescein and 8.71 g of toluene diisocyanate were added to a reactor. After reacting at 60°C for 2 hours, 20 g of polyethylene glycol (MW2000) was added, and the reaction was carried out at 80°C for 1 hour. The temperature was then lowered to 60°C, and 2.68 g of dimethylolpropionic acid was added. After reacting for 5 hours, the temperature was lowered to 25°C, and 2.5 g of sodium bisulfite was added. After reacting for 1 hour, 10 g of ethanol and 50 g of acetone were added, and the mixture was stirred for 0.5 hours. Then, 2.02 g of triethylamine was added, and the reaction was carried out for 1 hour. The mixture was filtered, and the filter cake was washed with 20 g of acetone each time, for a total of 3 washes. The filtrate was collected to obtain 159.23 g of an aqueous polyurethane solution of fluorescein isothiocyanate.

[0126] At 25℃, 154.16g of aqueous polyurethane solution, 159.23g of fluorescein aqueous polyurethane solution and 73.39g of bisphenol A epoxy resin (618) were added to a reactor and stirred for 0.5 hours. Then, 13.09g of sodium oleate, 15.93g of dioctyl adipate and 630g of water were added and emulsified at 7000rpm for 1 hour. Acetone and ethanol were removed by vacuum distillation, and the mixture was diluted with water to a solid content of 20% to obtain 879g of fluorescein isothiocyanate aqueous polyurethane sizing agent.

[0127] The isothiocyanate fluorescein aqueous polyurethane sizing agent prepared in this embodiment was diluted to 1.5% and used for sizing carbon fibers on a carbon fiber production line. The fibers were then dried at 120°C and wound up. The sizing adhesion of the carbon fibers after sizing was 1.2%, the saturated water absorption rate was 0.16%, and the ILSS was 31 MPa.

[0128] Comparative Example 2

[0129] Under a nitrogen atmosphere at room temperature, 6.96 g of toluene diisocyanate and 20 g of polyethylene glycol (MW2000) were added to a reactor. After reacting at 80°C for 1 hour, the temperature was lowered to 60°C, and 2.68 g of dimethylolpropionic acid was added. After reacting for 5 hours, the temperature was lowered to 25°C, and 2.5 g of sodium bisulfite was added. After reacting for 1 hour, 10 g of ethanol and 50 g of acetone were added, and the mixture was stirred for 0.5 hours. Then, 2.02 g of triethylamine was added, and the mixture was reacted for 1 hour. The mixture was filtered, and the filter cake was washed with 20 g of acetone each time, for a total of 3 washes. The filtrate was collected to obtain 154.16 g of aqueous polyurethane solution.

[0130] At 25°C, 154.16g of waterborne polyurethane solution and 10.2g of bisphenol A epoxy resin (618) were added to a reactor and stirred for 0.5 hours. Then, 1.83g of sodium oleate, 2.22g of dioctyl adipate and 180g of water were added, and the mixture was emulsified at 7000rpm for 1 hour. Acetone and ethanol were removed by vacuum distillation, and the mixture was diluted with water to a solid content of 20% to obtain 242.05g of waterborne polyurethane sizing agent.

[0131] The aqueous polyurethane sizing agent prepared in this embodiment was diluted to 1.5% and used on the carbon fiber production line for sizing treatment of carbon fibers. The fibers were then dried at 120°C and wound into fibers. The sizing adhesion of the carbon fibers after sizing was 1.2%, the saturated water absorption rate was 0.16%, and the ILSS was 39 MPa.

[0132] Comparative Example 3

[0133] Under a nitrogen atmosphere at room temperature, 8.71 g of toluene diisocyanate and 20 g of polyethylene glycol (MW2000) were added to a reactor. After reacting at 80°C for 1 hour, the temperature was lowered to 60°C, and 3.32 g of fluorescein was added. After reacting for 2 hours, 2.68 g of dimethylolpropionic acid was added. After reacting for 5 hours, the temperature was lowered to 25°C, and 2.5 g of sodium bisulfite was added. After reacting for 1 hour, 10 g of ethanol was added, and the mixture was stirred for 0.5 hours. The ethanol was removed by vacuum distillation, and 50 g of acetone was added. The mixture was filtered, and the filtrate was collected and placed in a reactor. 2.02 g of triethylamine was added to the reactor, and the mixture was reacted for 1 hour to obtain 89.23 g of an aqueous polyurethane solution of fluorescein.

[0134] Under a nitrogen atmosphere at room temperature, 6.96 g of toluene diisocyanate and 20 g of polyethylene glycol (MW2000) were added to a reactor. After reacting at 80°C for 1 hour, the temperature was lowered to 60°C, and 2.68 g of dimethylolpropionic acid was added. After reacting for 5 hours, the temperature was lowered to 25°C, and 2.5 g of sodium bisulfite was added. After reacting for 1 hour, 10 g of ethanol was added, and the mixture was stirred for 0.5 hours. The ethanol was removed by vacuum distillation, and 50 g of acetone was added. The mixture was filtered, and the filtrate was collected and placed in a reactor. 2.02 g of triethylamine was added to the reactor, and the mixture was reacted for 1 hour to obtain 84.16 g of an aqueous polyurethane solution.

[0135] At 25°C, 89.23g of fluorescein aqueous polyurethane solution and 84.16g of aqueous polyurethane solution were added to a reactor and stirred for 0.5 hours. Then, 360g of water was added, and acetone was removed by vacuum distillation. The mixture was diluted with water to a solid content of 20%, yielding 512.25g of fluorescein aqueous polyurethane solution.

[0136] The aqueous polyurethane sizing agent containing fluorescein isothiocyanate prepared in this embodiment was diluted to 1.5% and used for sizing carbon fibers on a carbon fiber production line. The fibers were then dried at 120°C and wound up. The sizing adhesion of the carbon fibers after sizing was 1.1%, the saturated water absorption rate was 0.07%, and the ILSS was 62 MPa.

[0137] Comparative Example 4

[0138] Under a nitrogen atmosphere at room temperature, 8.71 g of toluene diisocyanate and 20 g of polyethylene glycol (MW2000) were added to a reactor. After reacting at 80°C for 1 hour, the temperature was lowered to 60°C, and 3.32 g of fluorescein was added. After reacting for 2 hours, 2.68 g of dimethylolpropionic acid was added. After reacting for 5 hours, the temperature was lowered to 25°C, and 2.5 g of sodium bisulfite was added. After reacting for 1 hour, 10 g of ethanol was added, and the mixture was stirred for 0.5 hours. The ethanol was removed by vacuum distillation, and 50 g of acetone was added. The mixture was filtered, and the filtrate was collected and placed in a reactor. 2.02 g of triethylamine was added to the reactor, and the mixture was reacted for 1 hour to obtain 89.23 g of an aqueous polyurethane solution of fluorescein.

[0139] At 25°C, 89.23g of fluorescein aqueous polyurethane solution and 13.6g of bisphenol A epoxy resin (618) were added to a reactor and stirred for 0.5 hours. Then, 1.83g of sodium oleate, 2.22g of dioctyl adipate and 180g of water were added, and the mixture was emulsified at 7000rpm for 1 hour. Acetone and ethanol were removed by vacuum distillation, and the mixture was diluted with water to a solid content of 20% to obtain 284.4g of fluorescein isothiocyanate aqueous polyurethane sizing agent.

[0140] The isothiocyanate fluorescein aqueous polyurethane sizing agent prepared in this embodiment was diluted to 1.5% and used for sizing carbon fibers on a carbon fiber production line. The fibers were then dried at 120°C and wound up. The sizing adhesion of the carbon fibers after sizing was 1.2%, the saturated water absorption rate was 0.08%, and the ILSS was 85 MPa.

[0141] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A sizing agent comprising a main resin, excipients, and water, wherein the main resin comprises fluorescein-based waterborne polyurethane, waterborne polyurethane, and epoxy resin, and the excipients comprise plasticizers and surfactants, wherein... The general structural formula of fluorescein-based waterborne polyurethane is shown in formula (1): Equation (1) In formula (1), m is 1 to 10; n is 1 to 10; o is 1 to 10; R1 is ; R2 is , , , , , or ; R3 is ; R4 is ; R5 is ; R6 is or ; R7 is , , or ; The molar ratio of the epoxy resin to the waterborne polyurethane is (1~20):1; based on the molar amount of the waterborne polyurethane, the content of the plasticizer is (0.1~5):1; based on the molar amount of the waterborne polyurethane, the content of the surfactant is (0.1~5):1; and The plasticizer is selected from at least one of dioctyl diethyl phthalate, diisononyl phthalate, and dioctyl sebacate; The surfactant is selected from at least one of oleic acid, potassium oleate, sodium oleate, polyoxyethylene castor oil, polyoxyethylene sorbitan palmitate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monopalmitate, and polyoxyethylene monolaurate. In the sizing agent, the molar ratio of the fluorescein waterborne polyurethane to the waterborne polyurethane is (0.001~10):

1.

2. The sizing agent according to claim 1, characterized in that, The waterborne polyurethane is selected from at least one of polyether-type waterborne polyurethanes, which are prepared by a raw material system comprising polyether and diisocyanate; and / or The epoxy resin is selected from at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin and bisphenol S type epoxy resin.

3. The sizing agent according to claim 2, characterized in that, The polyether is at least one of polypropylene glycol, polyethylene glycol, and polytetrahydrofuran, and the diisocyanate is at least one of toluene diisocyanate, terephthalic diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dimethylbiphenyl diisocyanate, dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate.

4. The sizing agent according to any one of claims 1-3, characterized in that, In the sizing agent, the molar ratio of the fluorescein-based waterborne polyurethane to the waterborne polyurethane is (0.001~2):1; and / or The molar ratio of the epoxy resin to the waterborne polyurethane is (2~10):1; and / or Based on the total mass of the sizing agent, the water content is 50wt%~90wt%.

5. The sizing agent according to any one of claims 1-3, characterized in that, The molar ratio of the epoxy resin to the waterborne polyurethane is (4~10):1; and / or Based on the molar amount of the waterborne polyurethane, the plasticizer content is (0.5~2):1; and / or Based on the molar amount of the waterborne polyurethane, the content of the surfactant is (0.5~2):

1.

6. The sizing agent according to any one of claims 1-3, characterized in that, In the sizing agent, the molar ratio of the fluorescein waterborne polyurethane to the waterborne polyurethane is (0.001~1):

1.

7. A method for preparing a sizing agent according to any one of claims 1-6, comprising: The main resin, the auxiliary agent, and the water are mixed to obtain the sizing agent.

8. The method for preparing the sizing agent according to claim 7, comprising: S1. A mixed resin solution is prepared by mixing a solution containing the fluorescein-containing aqueous polyurethane, a solution containing the aqueous polyurethane, and the epoxy resin. S2. Mix the mixed resin solution, the auxiliary agent and water to obtain a concentrated sizing agent solution; S3. Optionally, the sizing agent concentrate is diluted with water to obtain the sizing agent.

9. The application of a sizing agent according to any one of claims 1-6 or a sizing agent prepared according to the preparation method of claim 7 or 8 as a sizing agent for carbon fibers.

10. A method for sizing carbon fiber, comprising diluting the sizing agent according to any one of claims 1-6 or the sizing agent prepared according to the preparation method of claim 7 or 8, and then subjecting the carbon fiber to sizing treatment.

11. The sizing method according to claim 10, characterized in that, The sizing agent is diluted to a solid content of 10wt%~50wt% and then used to sizing the carbon fiber.

12. A carbon fiber material comprising carbon fibers and a polymer film attached to the carbon fibers, the polymer film being formed on a sizing agent according to any one of claims 1-6 or a sizing agent prepared according to the preparation method of claim 7 or 8.

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