Preparation method and application of waterborne polyurethane resin for thermoplastic carbon fiber sizing agent

Abstract

The invention belongs to the technical field of polyurethane resins, and specifically relates to a method for preparing a thermoplastic carbon fiber sizing agent waterborne polyurethane resin and an application thereof, comprising the following steps: (1) preparing a prepolymer: mixing 72-76 parts of polyester polyol and 20-24 parts of isocyanate, reacting, continuously adding 13-16 parts of dihydroxymethylpropionic acid, 6-9 parts of 1,4-dihydroxy-2,2-dimethylpiperazine and 40-50 parts of acetone, reacting, adding 1-3 parts of triethylamine, reacting for 5-10 minutes, and then adding 2-4 parts of sodium ethylenediamine sulfonate to obtain a prepolymer; (2) emulsifying: transferring the prepolymer to an emulsifier, adding 280-300 parts of an ice-water mixture, stirring, adding 6-8 parts of an ethylenediamine aqueous solution with a mass fraction of 18-20%, standing for 20-24 hours, removing the acetone, adding a film-forming aid, a wetting agent, a defoaming agent and a lubricant, stirring evenly, and obtaining a waterborne polyurethane resin.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane resins, and particularly relates to a preparation method and application of a thermoplastic carbon fiber sizing agent waterborne polyurethane resin. Background Art

[0002] Sizing Agent for Thermoplastic Carbon Fibers is a material coated on the surface of carbon fiber to improve the interfacial bonding between carbon fiber and matrix resin, while protecting carbon fiber from mechanical damage. For thermoplastic composite materials, the selection of sizing agent is particularly important, because it must not only be able to remain stable at high temperatures, but also be able to promote good bonding between carbon fiber and thermoplastic resin. The role of sizing agent: Enhance interfacial bonding: Enhance the bonding between carbon fiber and thermoplastic resin through chemical bonds or other forms of interaction. Provide protection: Prevent carbon fiber from mechanical damage or chemical erosion during processing. Improve processability: Make carbon fiber easier to mix or shape with other materials, and improve processing efficiency.

[0003] Thermoplastic carbon fiber sizing agents face a series of technical challenges in practical applications, which may affect the performance and processing efficiency of composite materials. The following are several major technical issues: (1) Compatibility issues: The compatibility between thermoplastic resins and carbon fibers is poor, which may lead to delamination inside the composite material, thereby affecting the overall mechanical properties. The sizing agent needs to be designed to have good adhesion to the carbon fiber and be compatible with the specific thermoplastic resin. (2) Processing temperature: Thermoplastic composites often need to be processed at higher temperatures, which requires the sizing agent to remain stable at high temperatures and not easily decompose or denature, otherwise it will affect the interfacial bonding strength of the composite material. (3) Insufficient wettability: The surface of carbon fiber is relatively smooth and has poor wettability with certain thermoplastic resins, which makes it difficult for the resin to fully penetrate between the fiber bundles, thereby affecting the microstructure and macroscopic properties of the composite material. (4) Cost issues: High-efficiency thermoplastic carbon fiber sizing agents often contain expensive raw materials, which increases the production cost of composite materials and limits their application in certain fields. (5) Durability: Sizing agents may degrade under long-term use or extreme conditions, resulting in reduced performance of the composite material. Therefore, it is necessary to develop sizing agents with good weather resistance and chemical resistance. (6) Process adaptability: Different processing technologies have different requirements for sizing agents. For example, rapid prototyping processes may require fast-curing sizing agents, while traditional autoclave molding may focus more on the thermal stability of sizing agents.

[0004] Therefore, there is an urgent need for a preparation method and application of a thermoplastic carbon fiber sizing agent waterborne polyurethane resin. Summary of the invention

[0005] The purpose of the present invention is to provide a preparation method of a thermoplastic carbon fiber sizing agent waterborne polyurethane resin and application thereof.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for preparing a thermoplastic carbon fiber sizing agent waterborne polyurethane resin, the preparation method comprising the following steps:

[0008] (1) Preparation of prepolymer: 72-76 parts of polyester polyol and 20-24 parts of isocyanate are mixed, stirred and heated to 65-70°C, reacted for 2-3 hours, cooled to 40-45°C, and then 13-16 parts of dimethylol propionic acid, 6-9 parts of 1,4-dihydroxy-2,2-dimethylpiperazine and 40-50 parts of acetone are added, stirred and heated to 75-80°C, reacted for 4-5 hours, cooled to 30-35°C, 1-3 parts of triethylamine are added, reacted for 5-10 minutes, and then 2-4 parts of sodium ethylenediamine sulfonate are added, and the reaction time is 15-20 minutes to obtain a prepolymer;

[0009] (2) Emulsification: Transfer the prepolymer to an emulsifier, add 280-300 parts of ice-water mixture at a uniform speed while stirring at 1100-1300 r / min, continue stirring for 10-15 min, then adjust the speed to 550-600 r / min, add 6-8 parts of 18-20% by mass ethylenediamine aqueous solution, stir for 4-5 hours, let stand for 20-24 hours, remove acetone, add film-forming aid, wetting agent, defoamer and lubricant, stir evenly, and obtain waterborne polyurethane resin.

[0010] Furthermore, the isocyanate is selected from one or more of dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate.

[0011] Furthermore, the isocyanate includes dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate.

[0012] Furthermore, the weight ratio of the dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate is (3-5): (0.2-0.5): 1.

[0013] Furthermore, the preparation method of the polyester polyol comprises the following steps: adding adipic acid and 1,4-butanediol in a molar ratio of 2-2.4:1 into a reaction kettle, heating to 180°C-200°C, reacting for 4-6 hours, removing unreacted raw materials after the reaction is completed, cooling to room temperature, and obtaining polyester polyol.

[0014] Furthermore, the molecular weight of the polyester polyol is between 1800 and 2200.

[0015] Furthermore, the film-forming aid includes at least one of polyethylene glycol 200, polyethylene glycol 300, and polyethylene glycol 400.

[0016] Furthermore, the wetting agent is acetylene glycol.

[0017] Furthermore, the defoaming agent includes at least one of sodium hexametaphosphate, potassium tripolyphosphate and potassium pyrophosphate.

[0018] Furthermore, the lubricant is didecyl dimethyl ammonium chloride.

[0019] The invention provides an application of a method for preparing a thermoplastic carbon fiber sizing agent waterborne polyurethane resin in the preparation of the thermoplastic carbon fiber sizing agent.

[0020] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0021] The product of the present invention can make the thermoplastic chopped carbon fiber have good thermal bonding with particles such as PA66 and PBT. Compared with the carbon fiber product without adding such sizing agent, the product has stronger bonding with PA66 and PET, higher elastic modulus and better hydrolysis resistance.

[0022] The present invention uses a specific ratio of dicyclohexylmethane diisocyanate (XDI), hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) to prepare a waterborne polyurethane resin, and uses it as a thermoplastic carbon fiber sizing agent, which can significantly improve the tensile strength of the composite material. XDI, HDI and IPDI each have different chemical structures, and their distribution in the polyurethane network can form a complementary microstructure. XDI generally provides good heat resistance and mechanical strength; HDI can provide better flexibility; and IPDI can enhance chemical resistance and weather resistance. These properties combined can make the final polyurethane resin have higher tensile strength. Different isocyanates form different degrees of crosslinking when forming a polyurethane network. Reasonable crosslinking density can balance the rigidity and toughness of the material, thereby improving the tensile strength. Too high a crosslinking density will make the material brittle and hard, while too low a crosslinking density will make the material too soft. Appropriate crosslinking density helps to obtain optimal mechanical properties.

[0023] The present invention adds a film-forming aid, a wetting agent, a defoamer and a lubricant to the waterborne polyurethane, and these additives can significantly affect the tensile strength and conductivity of the waterborne polyurethane when used as a thermoplastic carbon fiber sizing agent. The film-forming aid can help the polyurethane resin form a continuous film at a lower temperature, which is beneficial for improving the film-forming quality and coverage of the sizing agent. However, if the amount added is too much or the selection is improper, the mechanical properties of the final composite material, especially the tensile strength, may be affected, because the excessive additive may cause the softening of the film layer, thereby weakening the bonding force between the fiber and the resin. The film-forming aid may affect the electrical properties of the carbon fiber surface, thereby indirectly affecting the conductivity of the composite material. If the film-forming aid forms an insulating film on the carbon fiber surface, the conductivity of the carbon fiber may be reduced. The defoamer can effectively reduce the bubbles generated during the sizing process, which is very important for ensuring the uniform distribution of the sizing agent on the carbon fiber and reducing the gap. Reducing the gap can increase the density of the material, thereby possibly increasing the tensile strength. If the defoamer is deposited on the carbon fiber surface, the conductivity may be affected. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Example 1

[0026] This embodiment provides a method for preparing a thermoplastic carbon fiber sizing agent waterborne polyurethane resin, the preparation method comprising the following steps:

[0027] (1) Preparation of prepolymer: 72 parts of polyester polyol and 24 parts of isocyanate were mixed, stirred and heated to 65°C, reacted for 3 hours, cooled to 40°C, and then 16 parts of dimethylol propionic acid, 6 parts of 1,4-dihydroxy-2,2-dimethylpiperazine and 50 parts of acetone were added, stirred and heated to 75°C for 5 hours, cooled to 35°C, 1 part of triethylamine was added, reacted for 10 minutes, and then 2 parts of sodium ethylenediamine sulfonate were added, and the reaction time was 20 minutes to obtain a prepolymer;

[0028] (2) Emulsification: Transfer the prepolymer to an emulsifier, add 300 parts of ice-water mixture at a uniform speed while stirring at 1100 r / min, continue stirring for 10 min, then adjust the speed to 600 r / min, add 6 parts of 20% by mass aqueous solution of ethylenediamine, stir for 4 hours, let stand for 24 hours, remove acetone, add film-forming aid, wetting agent, defoaming agent and lubricant, stir evenly, and obtain waterborne polyurethane resin.

[0029] The isocyanate comprises dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate; the weight ratio of the dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate is 4:0.3:1.

[0030] The preparation method of the polyester polyol comprises the following steps: adding adipic acid and 1,4-butanediol in a molar ratio of 2.4:1 into a reaction kettle, heating to 180° C., reacting for 6 hours, removing unreacted raw materials after the reaction is completed, cooling to room temperature, and obtaining the polyester polyol.

[0031] The molecular weight of the polyester polyol is 2000.

[0032] The film-forming aid includes polyethylene glycol 200, polyethylene glycol 300 and polyethylene glycol 400 in a weight ratio of 1:1.2:0.5.

[0033] The wetting agent is an acetylenic diol.

[0034] The defoaming agent includes at least one of sodium hexametaphosphate, potassium tripolyphosphate and potassium pyrophosphate in a weight ratio of 0.6:1.5:1.

[0035] The lubricant is didecyl dimethyl ammonium chloride.

[0036] Comparative Example 1

[0037] The difference between this comparative example and Example 1 is that the isocyanate is different.

[0038] A method for preparing a thermoplastic carbon fiber sizing agent waterborne polyurethane resin, the preparation method comprising the following steps:

[0039] (1) Preparation of prepolymer: 72 parts of polyester polyol and 24 parts of isocyanate were mixed, stirred and heated to 65°C, reacted for 3 hours, cooled to 40°C, and then 16 parts of dimethylol propionic acid, 6 parts of 1,4-dihydroxy-2,2-dimethylpiperazine and 50 parts of acetone were added, stirred and heated to 75°C for 5 hours, cooled to 35°C, 1 part of triethylamine was added, reacted for 10 minutes, and then 2 parts of sodium ethylenediamine sulfonate were added, and the reaction time was 20 minutes to obtain a prepolymer;

[0040] (2) Emulsification: Transfer the prepolymer to an emulsifier, add 300 parts of ice-water mixture at a uniform speed while stirring at 1100 r / min, continue stirring for 10 min, then adjust the speed to 600 r / min, add 6 parts of 20% by mass aqueous solution of ethylenediamine, stir for 4 hours, let stand for 24 hours, remove acetone, add film-forming aid, wetting agent, defoaming agent and lubricant, stir evenly, and obtain waterborne polyurethane resin.

[0041] The isocyanate includes dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate; the weight ratio of the dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate is 1:1:1.

[0042] The preparation method of the polyester polyol comprises the following steps: adding adipic acid and 1,4-butanediol in a molar ratio of 2.4:1 into a reaction kettle, heating to 180° C., reacting for 6 hours, removing unreacted raw materials after the reaction is completed, cooling to room temperature, and obtaining the polyester polyol.

[0043] The molecular weight of the polyester polyol is 2000.

[0044] The film-forming aid includes polyethylene glycol 200, polyethylene glycol 300 and polyethylene glycol 400 in a weight ratio of 1:1.2:0.5.

[0045] The wetting agent is an acetylenic diol.

[0046] The defoaming agent includes at least one of sodium hexametaphosphate, potassium tripolyphosphate and potassium pyrophosphate in a weight ratio of 0.6:1.5:1.

[0047] The lubricant is didecyl dimethyl ammonium chloride.

[0048] Comparative Example 2

[0049] The difference between this comparative example and Example 1 is that the isocyanate is different.

[0050] A method for preparing a thermoplastic carbon fiber sizing agent waterborne polyurethane resin, the preparation method comprising the following steps:

[0051] (1) Preparation of prepolymer: 72 parts of polyester polyol and 24 parts of isocyanate were mixed, stirred and heated to 65°C, reacted for 3 hours, cooled to 40°C, and then 16 parts of dimethylol propionic acid, 6 parts of 1,4-dihydroxy-2,2-dimethylpiperazine and 50 parts of acetone were added, stirred and heated to 75°C for 5 hours, cooled to 35°C, 1 part of triethylamine was added, reacted for 10 minutes, and then 2 parts of sodium ethylenediamine sulfonate were added, and the reaction time was 20 minutes to obtain a prepolymer;

[0052] (2) Emulsification: Transfer the prepolymer to an emulsifier, add 300 parts of ice-water mixture at a uniform speed while stirring at 1100 r / min, continue stirring for 10 min, then adjust the speed to 600 r / min, add 6 parts of 20% by mass aqueous solution of ethylenediamine, stir for 4 hours, let stand for 24 hours, remove acetone, add film-forming aid, wetting agent, defoaming agent and lubricant, stir evenly, and obtain waterborne polyurethane resin.

[0053] The isocyanate is dicyclohexylmethane diisocyanate.

[0054] The preparation method of the polyester polyol comprises the following steps: adding adipic acid and 1,4-butanediol in a molar ratio of 2.4:1 into a reaction kettle, heating to 180° C., reacting for 6 hours, removing unreacted raw materials after the reaction is completed, cooling to room temperature, and obtaining the polyester polyol.

[0055] The molecular weight of the polyester polyol is 2000.

[0056] The film-forming aid includes polyethylene glycol 200, polyethylene glycol 300 and polyethylene glycol 400 in a weight ratio of 1:1.2:0.5.

[0057] The wetting agent is an acetylenic diol.

[0058] The defoaming agent includes at least one of sodium hexametaphosphate, potassium tripolyphosphate and potassium pyrophosphate in a weight ratio of 0.6:1.5:1.

[0059] The lubricant is didecyl dimethyl ammonium chloride.

[0060] Comparative Example 3

[0061] The difference between this comparative example and Example 1 is that the polyester polyol is different.

[0062] A method for preparing a thermoplastic carbon fiber sizing agent waterborne polyurethane resin, the preparation method comprising the following steps:

[0063] (1) Preparation of prepolymer: 72 parts of polyester polyol and 24 parts of isocyanate were mixed, stirred and heated to 65°C, reacted for 3 hours, cooled to 40°C, and then 16 parts of dimethylol propionic acid, 6 parts of 1,4-dihydroxy-2,2-dimethylpiperazine and 50 parts of acetone were added, stirred and heated to 75°C for 5 hours, cooled to 35°C, 1 part of triethylamine was added, reacted for 10 minutes, and then 2 parts of sodium ethylenediamine sulfonate were added, and the reaction time was 20 minutes to obtain a prepolymer;

[0064] (2) Emulsification: Transfer the prepolymer to an emulsifier, add 300 parts of ice-water mixture at a uniform speed while stirring at 1100 r / min, continue stirring for 10 min, then adjust the speed to 600 r / min, add 6 parts of 20% by mass aqueous solution of ethylenediamine, stir for 4 hours, let stand for 24 hours, remove acetone, add film-forming aid, wetting agent, defoaming agent and lubricant, stir evenly, and obtain waterborne polyurethane resin.

[0065] The isocyanate comprises dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate; the weight ratio of the dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate is 4:0.3:1.

[0066] The preparation method of the polyester polyol comprises the following steps: adding terephthalic acid and 1,4-butanediol in a molar ratio of 2.4:1 into a reaction kettle, heating to 180° C., reacting for 3 hours, removing unreacted raw materials after the reaction is completed, cooling to room temperature, and obtaining the polyester polyol.

[0067] The molecular weight of the polyester polyol is 1500.

[0068] The film-forming aid includes polyethylene glycol 200, polyethylene glycol 300 and polyethylene glycol 400 in a weight ratio of 1:1.2:0.5.

[0069] The wetting agent is an acetylenic diol.

[0070] The defoaming agent includes at least one of sodium hexametaphosphate, potassium tripolyphosphate and potassium pyrophosphate in a weight ratio of 0.6:1.5:1.

[0071] The lubricant is didecyl dimethyl ammonium chloride.

[0072] Comparative Example 4

[0073] The difference between this comparative example and Example 1 is that the film-forming aid is different.

[0074] A method for preparing a thermoplastic carbon fiber sizing agent waterborne polyurethane resin, the preparation method comprising the following steps:

[0075] (1) Preparation of prepolymer: 72 parts of polyester polyol and 24 parts of isocyanate were mixed, stirred and heated to 65°C, reacted for 3 hours, cooled to 40°C, and then 16 parts of dimethylol propionic acid, 6 parts of 1,4-dihydroxy-2,2-dimethylpiperazine and 50 parts of acetone were added, stirred and heated to 75°C for 5 hours, cooled to 35°C, 1 part of triethylamine was added, reacted for 10 minutes, and then 2 parts of sodium ethylenediamine sulfonate were added, and the reaction time was 20 minutes to obtain a prepolymer;

[0076] (2) Emulsification: Transfer the prepolymer to an emulsifier, add 300 parts of ice-water mixture at a uniform speed while stirring at 1100 r / min, continue stirring for 10 min, then adjust the speed to 600 r / min, add 6 parts of 20% by mass aqueous solution of ethylenediamine, stir for 4 hours, let stand for 24 hours, remove acetone, add film-forming aid, wetting agent, defoaming agent and lubricant, stir evenly, and obtain waterborne polyurethane resin.

[0077] The isocyanate comprises dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate; the weight ratio of the dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate is 4:0.3:1.

[0078] The preparation method of the polyester polyol comprises the following steps: adding adipic acid and 1,4-butanediol in a molar ratio of 2.4:1 into a reaction kettle, heating to 180° C., reacting for 6 hours, removing unreacted raw materials after the reaction is completed, cooling to room temperature, and obtaining the polyester polyol.

[0079] The molecular weight of the polyester polyol is 2000.

[0080] The film-forming aid includes polyethylene glycol 200, polyethylene glycol 300 and polyethylene glycol 400 in a weight ratio of 1:1:1.

[0081] The wetting agent is an acetylenic diol.

[0082] The defoaming agent includes at least one of sodium hexametaphosphate, potassium tripolyphosphate and potassium pyrophosphate in a weight ratio of 0.6:1.5:1.

[0083] The lubricant is didecyl dimethyl ammonium chloride.

[0084] Comparative Example 5

[0085] The difference between this comparative example and Example 1 is that the defoaming agents are different.

[0086] A method for preparing a thermoplastic carbon fiber sizing agent waterborne polyurethane resin, the preparation method comprising the following steps:

[0087] (1) Preparation of prepolymer: 72 parts of polyester polyol and 24 parts of isocyanate were mixed, stirred and heated to 65°C, reacted for 3 hours, cooled to 40°C, and then 16 parts of dimethylol propionic acid, 6 parts of 1,4-dihydroxy-2,2-dimethylpiperazine and 50 parts of acetone were added, stirred and heated to 75°C for 5 hours, cooled to 35°C, 1 part of triethylamine was added, reacted for 10 minutes, and then 2 parts of sodium ethylenediamine sulfonate were added, and the reaction time was 20 minutes to obtain a prepolymer;

[0088] (2) Emulsification: Transfer the prepolymer to an emulsifier, add 300 parts of ice-water mixture at a uniform speed while stirring at 1100 r / min, continue stirring for 10 min, then adjust the speed to 600 r / min, add 6 parts of 20% by mass aqueous solution of ethylenediamine, stir for 4 hours, let stand for 24 hours, remove acetone, add film-forming aid, wetting agent, defoaming agent and lubricant, stir evenly, and obtain waterborne polyurethane resin.

[0089] The isocyanate comprises dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate; the weight ratio of the dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate is 4:0.3:1.

[0090] The preparation method of the polyester polyol comprises the following steps: adding adipic acid and 1,4-butanediol in a molar ratio of 2.4:1 into a reaction kettle, heating to 180° C., reacting for 6 hours, removing unreacted raw materials after the reaction is completed, cooling to room temperature, and obtaining the polyester polyol.

[0091] The molecular weight of the polyester polyol is 2000.

[0092] The film-forming aid includes polyethylene glycol 200, polyethylene glycol 300 and polyethylene glycol 400 in a weight ratio of 1:1.2:0.5.

[0093] The wetting agent is an acetylenic diol.

[0094] The defoaming agent includes at least one of sodium hexametaphosphate, potassium tripolyphosphate and potassium pyrophosphate in a weight ratio of 1:1:1.

[0095] The lubricant is didecyl dimethyl ammonium chloride.

[0096] Performance Testing

[0097] The water-based polyurethane resin prepared in Example 1 and Comparative Examples 1-5 was impregnated with carbon fiber filaments (T300-12000 produced by Toray Industries, Ltd., Japan, with a fineness of 800g / 1000m. Before use, the carbon fiber filaments were heated at 350°C for 4 hours under a nitrogen atmosphere to remove the original sizing agent) for 10 minutes, then heat-treated at 100°C for 10 minutes to remove the moisture in the sizing agent, and then heat-treated at 150°C for 30 minutes to obtain sized carbon fibers. The content of water-based polyurethane resin on the surface of the carbon fibers accounted for 10% of the total mass of the treated carbon fibers. The tensile strength in the fiber filament direction and the thermal conductivity in the thickness direction were tested. The test results are shown in Table 1.

[0098] Table 1 Performance test results

[0099]

[0100] It can be seen from Table 1 that the waterborne polyurethane resin of the present invention has excellent effects.

[0101] Comparing Example 1 with Comparative Examples 1-2, it can be seen that the isocyanate described in the present invention can significantly improve the tensile strength effect. The present invention uses a specific ratio of dicyclohexylmethane diisocyanate (XDI), hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) to prepare an aqueous polyurethane resin, and uses it as a thermoplastic carbon fiber sizing agent, which can significantly improve the tensile strength of the composite material. XDI, HDI and IPDI each have a different chemical structure, and their distribution in the polyurethane network can form a complementary microstructure. Comparing Example 1 with Comparative Example 3, it can be seen that the polyester polyol prepared by the preparation method of the present invention can significantly improve the tensile strength effect. Comparing Example 1 with Comparative Example 3, it can be seen that the film-forming aid and defoamer of the present invention can be used to obtain an aqueous polyurethane resin with excellent comprehensive performance.

[0102] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a thermoplastic carbon fiber sizing agent waterborne polyurethane resin, characterized in that: The preparation method comprises the following steps: (1) Preparation of prepolymer: 72-76 parts of polyester polyol and 20-24 parts of isocyanate are mixed, stirred and heated to 65-70°C, reacted for 2-3 hours, cooled to 40-45°C, and then 13-16 parts of dimethylol propionic acid, 6-9 parts of 1,4-dihydroxy-2,2-dimethylpiperazine and 40-50 parts of acetone are added, stirred and heated to 75-80°C, reacted for 4-5 hours, cooled to 30-35°C, 1-3 parts of triethylamine are added, reacted for 5-10 minutes, and then 2-4 parts of sodium ethylenediamine sulfonate are added, and the reaction time is 15-20 minutes to obtain a prepolymer; (2) Emulsification: Transfer the prepolymer to an emulsifier, add 280-300 parts of ice-water mixture at a uniform speed while stirring at 1100-1300 r / min, continue stirring for 10-15 min, then adjust the speed to 550-600 r / min, add 6-8 parts of 18-20% by mass ethylenediamine aqueous solution, stir for 4-5 hours, let stand for 20-24 hours, remove acetone, add film-forming aid, wetting agent, defoamer and lubricant, stir evenly, and prepare waterborne polyurethane resin; The isocyanate comprises dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate; wherein the weight ratio of dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate is (3-5): (0.2-0.5): 1; The preparation method of the polyester polyol comprises the following steps: adding adipic acid and 1,4-butanediol in a molar ratio of 2-2.4:1 into a reaction kettle, heating to 180°C-200°C, reacting for 4-6 hours, removing unreacted raw materials after the reaction is completed, cooling to room temperature, and obtaining a polyester polyol; the molecular weight of the polyester polyol is 1800-2200; the film-forming aid comprises polyethylene glycol 200, polyethylene glycol 300 and polyethylene glycol 400 in a weight ratio of 1:1.2:0.5; The defoaming agent includes sodium hexametaphosphate, potassium tripolyphosphate and potassium pyrophosphate in a weight ratio of 0.6:1.5:

1.

2. The method for preparing a thermoplastic carbon fiber sizing agent waterborne polyurethane resin according to claim 1, characterized in that: The wetting agent is acetylene glycol; the lubricant is didecyl dimethyl ammonium chloride.

3. Application of the aqueous polyurethane resin prepared by the method for preparing an aqueous polyurethane resin for a thermoplastic carbon fiber sizing agent as claimed in claim 1 in a thermoplastic carbon fiber sizing agent.

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