A sizing agent composition for vinyl carbon fiber modified by carbon nanotubes, its preparation method and application

Abstract

The present invention provides a sizing agent composition for carbon nanotube-modified vinyl carbon fiber, a preparation method thereof, and an application thereof, including an isocyanate-modified vinyl resin prepolymer (film-forming agent) and carbon nanotubes; each mole of the isocyanate-modified vinyl resin prepolymer contains 2 to 4 moles of ester groups; the isocyanate-modified vinyl resin prepolymer has a structure shown in formula (IV). The sizing agent composition of the present invention is modified with carbon nanotubes, which can effectively improve the interfacial properties between the carbon fiber and the composite matrix. The low density of the ester groups in the film-forming agent improves the hydrolysis resistance of the composite material and further improves the corrosion resistance in media. The polar groups in the molecular structure improve the adhesion between the sizing agent and the carbon fiber. By modifying the vinyl resin with polyurethane, the two ends of the vinyl structure contain unsaturated carbon-carbon double bonds, which can crosslink and cure with the vinyl resin, endowing the carbon fiber composite with excellent mechanical properties and excellent fatigue resistance of the composite material.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon fiber composite materials, and particularly to a sizing agent composition for vinyl carbon fiber modified by carbon nanotubes and a preparation method thereof. Background Art

[0002] Carbon fiber composites have the characteristics of light weight, high strength, and good designability, and are widely used in the fields of rail transit, aerospace, marine ships, wind power, new energy, etc. Organic fibers are prepared into raw filaments through processes such as spinning, oiling, and heat setting, and then are prepared into carbon fibers through processes such as pre-oxidation, carbonization, and sizing. The sizing agent covers the surface of the carbon fiber to play a protective role and endows the carbon fiber with good processability. To improve the performance of carbon fiber composites, it is necessary to select a sizing agent type that is compatible with the resin matrix. Vinyl resin has the advantages of good seawater corrosion resistance and salt spray resistance, and is increasingly widely used in the fields of marine ships, offshore wind power, oil drilling platforms, and submarine cables. Carbon fiber composites using vinyl resin need to select a sizing agent containing unsaturated carbon-carbon double bonds.

[0003] CN112679717A discloses the preparation, product, and application of a multi-purpose self-emulsifying anionic unsaturated polyester carbon fiber sizing agent. Binary fatty acids / or anhydrides, diol monomers, and maleic anhydride are used for polymerization reaction, epoxy resin and a catalyst are added for reaction, and then an anhydride is added for carboxylation reaction to prepare a self-emulsifying anionic polyester carbon fiber sizing agent. The sizing agent made of such unsaturated polyester resin has the following disadvantages: (1) Unsaturated polyester resin is polymerized from diols and dibasic acids, with few surface polar groups, and the interface performance between the prepared sizing agent and carbon fiber is poor; (2) The proportion of unsaturated double bonds in unsaturated polyester resin is high, and the unsaturated double bonds are rigid structures, with poor wear resistance, which affects the carbon fiber weaving process. In addition, traditional unsaturated polyester resins adopt a saturated dibasic acid structure, with a high proportion of benzene rings, and the benzene rings are also rigid structures, further reducing the wear resistance of carbon fibers; (3) During the synthesis of unsaturated polyester, esterification reaction occurs between diols and dibasic acids to generate ester groups, and the ester groups are prone to hydrolysis under acidic or alkaline conditions, resulting in poor seawater and chemical medium corrosion resistance, which limits the use of carbon fiber composites in marine environments. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a sizing agent composition for vinyl carbon fiber modified by carbon nanotubes and a preparation method thereof, which have the characteristics of good interface performance with carbon fiber, high wear resistance, and low ester group density, and are suitable for carbon fiber vinyl resin composites used in the marine field.

[0005] To achieve the above-mentioned invention object, a first aspect of the present invention provides a sizing agent composition for carbon nanotube-modified vinyl carbon fiber, which comprises an isocyanate-modified vinyl resin prepolymer and carbon nanotubes; each mole of the isocyanate-modified vinyl resin prepolymer contains 2 to 4 moles of ester groups; the isocyanate-modified vinyl resin prepolymer has a structure as shown in formula (IV):

[0006]

[0007] Wherein, R4 is selected from the following structures:

[0008]

[0009] The structure of R5 is:

[0010]

[0011] R1 is H or CH3; n2 is any integer from 1 to 3;

[0012] R2 is H or CH3; n1 is any integer from 1 to 4;

[0013] R3 is selected from one or more of the following structures:

[0014]

[0015] n3 is any integer from 1 to 3.

[0016] Preferably, the isocyanate-modified vinyl resin prepolymer is obtained by reacting a vinyl resin prepolymer with an end group of an unsaturated carbon-carbon double bond and a diisocyanate polyether resin with an end group of an isocyanate group; the diisocyanate polyether resin with an end group of an isocyanate group does not contain a benzene ring in its molecule; the vinyl resin prepolymer with an end group of an unsaturated carbon-carbon double bond includes a tetrahydrofuran polyether vinyl resin with an end group of an unsaturated carbon-carbon double bond and a bisphenol A polyether vinyl resin with an end group of an unsaturated carbon-carbon double bond; the tetrahydrofuran polyether vinyl resin with an end group of an unsaturated carbon-carbon double bond does not contain a benzene ring and has a linear structure in the chain segment; each mole of the isocyanate-modified vinyl resin prepolymer contains 2 to 4 moles or less of ester groups.

[0017] Preferably, the molar ratio of the tetrahydrofuran polyether vinyl resin with an end group of an unsaturated carbon-carbon double bond to the bisphenol A polyether vinyl resin with an end group of an unsaturated carbon-carbon double bond is 1:5 to 5:1. Further preferably, the molar ratio of the tetrahydrofuran polyether vinyl resin with an end group of an unsaturated carbon-carbon double bond to the bisphenol A polyether vinyl resin with an end group of an unsaturated carbon-carbon double bond is 1:1 to 1:3.

[0018] Preferably, the tetrahydrofuran polyether vinyl resin with an unsaturated carbon-carbon double bond at the end group has the structure shown in formula (I):

[0019]

[0020] Wherein, R2 is H or CH3; n1 is any integer from 1 to 4. Further preferably, R2 is CH3; n1 is 2.

[0021] Preferably, the tetrahydrofuran polyether vinyl resin with an unsaturated carbon-carbon double bond at the end group is obtained by reacting a tetrahydrofuran polyether epoxy resin with an unsaturated monocarboxylic acid. Further preferably, the tetrahydrofuran polyether epoxy resin is formed by the etherification and cyclization reactions of tetrahydrofuran polyether, epichlorohydrin and sodium hydroxide.

[0022] Preferably, the bisphenol A polyether vinyl resin with an unsaturated carbon-carbon double bond at the end group has the structure shown in formula (II):

[0023]

[0024] Wherein, R1 is H or CH3; n2 is any integer from 1 to 3. Further preferably, R1 is CH3; n2 is 3.

[0025] Preferably, the bisphenol A polyether vinyl resin with an unsaturated carbon-carbon double bond at the end group is obtained by reacting a bisphenol A polyether epoxy resin with an unsaturated monocarboxylic acid. Further preferably, the polyether group in the bisphenol A polyether epoxy resin is an ether bond structure introduced by polypropylene glycol or polyethylene glycol.

[0026] Preferably, the diisocyanate polyether resin with an isocyanate group at the end group has the structure shown in formula (III):

[0027]

[0028] Wherein, R3 is selected from one or more of the following structures:

[0029]

[0030] n3 is any integer from 1 to 3.

[0031] Preferably, the diisocyanate polyether resin with an isocyanate group at the end group is obtained by the ring-opening reaction of an isocyanate with a tetrahydrofuran polyether.

[0032] Preferably, the sizing agent composition is made from the following raw materials by weight percentage:

[0033]

[0034] Further preferably, the sizing agent composition is made from raw materials in the following weight percentages:

[0035]

[0036]

[0037] Preferably, the molecular weight of the tetrahydrofuran polyether epoxy resin is 800 - 1200;

[0038] Preferably, the molecular weight of the bisphenol A polyether epoxy resin is 500 - 700;

[0039] Preferably, the unsaturated monocarboxylic acid is selected from acrylic acid and / or methacrylic acid;

[0040] Preferably, the isocyanate is selected from one or more of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate;

[0041] Preferably, the molecular weight of the tetrahydrofuran polyether is 200 - 800;

[0042] Preferably, the catalyst is selected from one or more of benzyltrimethylammonium chloride, triphenylphosphine, benzyltriethylammonium chloride, and benzyltriethylammonium bromide;

[0043] Preferably, the polymerization inhibitor is selected from one or more of hydroquinone, p - benzoquinone, tert - butylhydroquinone, 2,6 - di - tert - butyl - 4 - methylphenol, methylhydroquinone, and p - methoxyphenol;

[0044] Preferably, the carbon nanotube is a multi - walled carbon nanotube with an outer diameter of 1 - 99 nm;

[0045] Preferably, the resistivity of the deionized water is greater than 0.5 MΩ·cm;

[0046] Preferably, the emulsifier is an anionic emulsifier, and the emulsifier is selected from one or more of alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkyl sulfonates, alkylphenol polyoxyethylene ether sulfates, and aralkylphenol polyoxyethylene ether sulfates.

[0047] The second aspect of the present invention provides a preparation method of the sizing agent composition for carbon nanotube - modified vinyl carbon fiber according to the above - mentioned technical solution, including the following steps:

[0048] S1, mix the tetrahydrofuran polyether epoxy resin, bisphenol A polyether epoxy resin, polymerization inhibitor, and unsaturated monocarboxylic acid, add the catalyst at 90°C - 120°C, and continuously react until the acid value reaches 10 ± 3 mgKOH / g to obtain a vinyl resin prepolymer with unsaturated carbon - carbon double bonds at the end groups;

[0049] The vinyl resin prepolymer with an unsaturated carbon-carbon double bond as the end group includes a tetrahydrofuran polyether vinyl resin with an unsaturated carbon-carbon double bond as the end group and a bisphenol A polyether vinyl resin with an unsaturated carbon-carbon double bond as the end group;

[0050] S2. At 40 °C to 50 °C, dropwise add tetrahydrofuran polyether to the isocyanate and continuously react until the hydroxyl value reaches 0 mgKOH / g to obtain a diisocyanate polyether resin with an isocyanate group as the end group;

[0051] S3. Add the diisocyanate polyether resin with an isocyanate group as the end group to the vinyl resin prepolymer at 55 °C to 60 °C. The isocyanate of the diisocyanate polyether resin reacts with the hydroxyl group obtained by ring-opening of the epoxy group in the vinyl resin prepolymer, and continue to react until the isocyanate group is 0 to obtain an isocyanate-modified vinyl resin prepolymer;

[0052] S4. At 60 to 70 °C, add an emulsifier, carbon nanotubes and water to the isocyanate-modified vinyl resin prepolymer in sequence to obtain a carbon nanotube-modified sizing agent for vinyl carbon fiber;

[0053] There is no order restriction for steps S1 and S2.

[0054] Preferably, in step S1, the molar ratio of tetrahydrofuran polyether epoxy resin to bisphenol A polyether epoxy resin is 1:5 to 5:1; more preferably, the molar ratio of tetrahydrofuran polyether epoxy resin to bisphenol A polyether epoxy resin is 1:1 to 1:3;

[0055] Preferably, the tetrahydrofuran polyether epoxy resin is formed by etherification and cyclization reactions of tetrahydrofuran polyether, epichlorohydrin and sodium hydroxide, and the molecular weight is 400 to 1600;

[0056] Preferably, the polyether group in the bisphenol A polyether epoxy resin is an ether bond structure introduced by polypropylene glycol or polyethylene glycol, and the molecular weight is 250 to 750;

[0057] Preferably, the unsaturated monocarboxylic acid is selected from acrylic acid and / or methacrylic acid;

[0058] Preferably, the polymerization inhibitor is selected from one or more of hydroquinone, p-benzoquinone, tert-butylhydroquinone, 2,6-ditert-butyl-4-methylphenol, methylhydroquinone and p-methoxyphenol.

[0059] Preferably, step S1 is: mix tetrahydrofuran polyether epoxy resin, bisphenol A polyether epoxy resin, polymerization inhibitor and unsaturated monocarboxylic acid, stir for 10 to 15 min, add a catalyst at 90 °C, and heat up to 120 °C at a rate of 6 °C to 8 °C / h, and continuously react until the acid value reaches 10 ± 3 mgKOH / g to obtain a vinyl resin prepolymer with an unsaturated carbon-carbon double bond as the end group.

[0060] Preferably, the reaction temperature in step S2 is 45°C ± 2°C;

[0061] Preferably, the reaction temperature in step S3 is 60°C ± 2°C;

[0062] Preferably, the isocyanate is selected from one or more of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate;

[0063] Preferably, the molecular weight of the tetrahydrofuran polyether is 200 - 800.

[0064] Preferably, the emulsifier is an anionic emulsifier, and the emulsifier is selected from one or more of alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkyl sulfonates, alkylphenol polyoxyethylene ether sulfates, and aralkylphenol polyoxyethylene ether sulfates;

[0065] Preferably, the carbon nanotubes are multi-walled carbon nanotubes with an outer diameter of 1 - 99 nm;

[0066] Preferably, the resistivity of the deionized water is greater than 0.5 MΩ·cm;

[0067] Preferably, the reaction temperature in step S4 is 65°C ± 2°C.

[0068] Preferably, step S4 is as follows: at 65°C ± 2°C, an emulsifier is added to the isocyanate-modified vinyl resin prepolymer, and stirred for 10 - 15 minutes, then carbon nanotubes are added, and stirring is continued for 10 - 15 minutes, 30% by mass of deionized water is added, and stirring is continued for 55 - 65 minutes, and the remaining deionized water is added, and stirring is continued for 55 - 65 minutes to obtain a carbon nanotube-modified vinyl carbon fiber sizing agent.

[0069] The third aspect of the present invention provides the application of the carbon nanotube-modified vinyl carbon fiber sizing agent composition described in the foregoing technical solution or the carbon nanotube-modified vinyl carbon fiber sizing agent composition obtained by the preparation method described in the above technical solution in the preparation of a carbon fiber vinyl resin composite suitable for a marine environment.

[0070] The fourth aspect of the present invention provides a carbon fiber vinyl resin composite suitable for a marine environment, which sequentially includes carbon fibers, a carbon nanotube-modified vinyl carbon fiber sizing agent composition, and a vinyl resin matrix from the inside to the outside.

[0071] Compared with the prior art, the beneficial effects of the present invention:

[0072] The carbon nanotube-modified vinyl carbon fiber sizing agent composition of the present invention is modified with carbon nanotubes, which can effectively increase the interface performance between carbon fiber and composite material matrix. The isocyanate-modified vinyl resin prepolymer in the sizing agent is a film-forming agent, in which the proportion of benzene rings and unsaturated double bonds is lower than that of unsaturated polyesters in the prior art, and the linear structure of tetrahydrofuran improves the wear resistance. The ester group density of the film-forming agent is low, which improves the hydrolysis resistance of the composite material and further improves the medium corrosion resistance. The molecular structure contains polar groups, which improves the adhesion between the sizing agent and the carbon fiber. The vinyl resin is modified by polyurethane, and the two ends of the vinyl structure contain unsaturated carbon-carbon double bonds, which can be cross-linked and cured with the vinyl resin, giving the carbon fiber composite material excellent mechanical properties, and the polyurethane structure gives the composite material excellent fatigue resistance. Specifically:

[0073] 1) Isocyanate-modified vinyl resin prepolymer is a polyurethane-modified vinyl resin structure, and unsaturated carbon-carbon double bonds are set at both ends of the vinyl resin, which can be cross-linked and cured with the vinyl resin matrix, giving the carbon fiber vinyl resin composite material excellent mechanical properties; the isocyanate-modified vinyl resin prepolymer is also modified with a polyurethane structure, giving the carbon fiber vinyl resin composite material excellent fatigue resistance.

[0074] 2) The present invention uses an isocyanate-modified vinyl resin prepolymer as a film-forming agent, wherein each mol of the isocyanate-modified vinyl resin prepolymer contains less than 2 mol of ester groups, while the prior art unsaturated polyester sizing agent with the same molecular weight contains 4 to 7 mol of ester groups. The ester group density in the film-forming agent is greatly reduced, making the sizing agent and the carbon fiber vinyl resin composite material more resistant to hydrolysis and corrosion (such as seawater and chemical medium corrosion);

[0075] In some preferred embodiments of the present invention, when the unsaturated monobasic acid is methacrylic acid, the ester group of the film-forming agent is protected by the side chain methyl group, which can further improve the hydrolysis resistance and further improve the seawater resistance and chemical medium corrosion resistance.

[0076] 3) In order to solve the problem of low surface energy of carbon fiber, the present invention introduces polar groups such as ether bonds, hydroxyl groups, and isocyanate structures into the film-forming agent to improve the adhesion between the sizing agent and the carbon fiber.

[0077] 4) The proportion of benzene rings and unsaturated double bonds in the film-forming agent is lower than that of unsaturated polyester, and the linear structure of tetrahydrofuran improves the wear resistance.

[0078] 5) In the sizing agent composition of the present invention, the isocyanate-modified vinyl resin prepolymer is attached to the outside of the carbon nanotubes to form a film during preparation. The carbon nanotubes have an aspect ratio structure. When the isocyanate-modified vinyl resin prepolymer is evenly wrapped around the surface of the carbon fiber, the surface roughness and specific surface area of the carbon fiber can be effectively increased, thereby effectively increasing the interface performance between the carbon fiber and the composite material matrix. Detailed implementation manners

[0079] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0080] The present invention provides a sizing agent composition for vinyl carbon fiber modified with carbon nanotubes, which is made from the following raw materials in weight percentages:

[0081]

[0082] In the present invention, tetrahydrofuran polyether epoxy resin reacts with unsaturated monocarboxylic acid to form tetrahydrofuran polyether vinyl resin with unsaturated carbon-carbon double bonds at the end groups, having the structure shown in formula (I):

[0083]

[0084] Among them, R2 is H or CH3; n1 is any integer from 1 to 4, such as 1, 2, 3, 4.

[0085] In the present invention, the tetrahydrofuran polyether epoxy resin does not contain a benzene ring and has a linear structure in the chain segment, improving wear resistance and flexibility. Preferably in the present invention, the tetrahydrofuran polyether epoxy resin is formed by the etherification and cyclization reactions of tetrahydrofuran polyether, epichlorohydrin, and sodium hydroxide, with a molecular weight of 400-1600. Further preferably, the tetrahydrofuran polyether epoxy resin selected in the present invention has a molecular weight of 800-1200. In some specific implementation manners of the present invention, the tetrahydrofuran polyether epoxy resin is the compound of formula (I) with R2 being CH3 and n1 being 2, and the molecular weight is 1050. In the present invention, the weight percentage content of the tetrahydrofuran polyether epoxy resin in the raw materials is preferably 12.0% - 24.0%; in some specific implementations of the present invention, the weight percentage content of the tetrahydrofuran polyether epoxy resin is 20.38%, 23.72%, 23.61%, 12.84%, 12.43%.

[0086] In the present invention, bisphenol A polyether epoxy resin reacts with unsaturated monocarboxylic acid to form vinyl resin with unsaturated carbon-carbon double bonds at the end groups, having the structure shown in formula (II):

[0087]

[0088] Among them, R1 is H or CH3; n2 is any integer from 1 to 3. Further preferably, R1 is CH3; n2 is 3.

[0089] In the present invention, the bisphenol A polyether epoxy resin contains an ether bond, and the ether bond is a hydrophilic group, which can improve the emulsification effect of the polymer. Preferably, in the present invention, the polyether group in the bisphenol A polyether epoxy resin is an ether bond structure introduced by polypropylene glycol or polyethylene glycol, with a molecular weight of 250 to 750. In some preferred embodiments of the present invention, the bisphenol A polyether epoxy resin is a compound of formula (II) where R1 is CH3 and n2 is 3, with a molecular weight of 667. In the present invention, the weight percentage content of the bisphenol A polyether epoxy resin in the raw materials is preferably 12.0% to 24.5%; in some specific embodiments of the present invention, the weight percentage content of the tetrahydrofuran polyether epoxy resin is 12.95%, 15.07%, 15%, 24.46%, 23.68%.

[0090] In the present invention, the unsaturated monocarboxylic acid is preferably selected from acrylic acid and / or methacrylic acid. In some preferred embodiments of the present invention, the unsaturated monocarboxylic acid is methacrylic acid. The ester group of the isocyanate-modified vinyl resin prepolymer (film-forming agent) made from it is protected by the side-chain methyl group, which can further improve the hydrolysis resistance and further improve the corrosion resistance to seawater and chemical media. In the present invention, the weight percentage of the unsaturated monocarboxylic acid in the raw materials is preferably 6.0% to 9.0%; in some specific embodiments of the present invention, the weight percentage of the unsaturated monocarboxylic acid in the raw materials is 6.68%, 7.77%, 7.73%, 8.41%, 8.14%.

[0091] In the present invention, the molar ratio of the tetrahydrofuran polyether epoxy resin to the bisphenol A polyether epoxy resin in the raw materials is preferably 1:5 to 5:1, and further preferably 1:1 to 1:3; in some specific embodiments of the present invention, the molar ratio of the tetrahydrofuran polyether epoxy resin to the bisphenol A polyether epoxy resin in the raw materials is 1:1, 1:3. In the present invention, the number of moles of the unsaturated monocarboxylic acid in the raw materials is the sum of the number of moles of the tetrahydrofuran polyether epoxy resin and the bisphenol A polyether epoxy resin. Further, the molar ratio of the tetrahydrofuran polyether vinyl resin with an unsaturated carbon-carbon double bond at the end group to the bisphenol A polyether vinyl resin with an unsaturated carbon-carbon double bond at the end group obtained by reacting the above raw materials is 1:5 to 5:1. Further preferably, the molar ratio of the tetrahydrofuran polyether vinyl resin with an unsaturated carbon-carbon double bond at the end group to the bisphenol A polyether vinyl resin with an unsaturated carbon-carbon double bond at the end group is 1:1 to 1:3. The two epoxy resins react with the unsaturated monocarboxylic acid to form a vinyl resin with an unsaturated carbon-carbon double bond at the end group, which can be crosslinked and cured with the composite matrix to improve the interfacial properties. At the same time, the molecular structure does not contain an unsaturated carbon-carbon double bond, and the ester group density is low, and the corrosion resistance to seawater and chemical media is good.

[0092] In the present invention, tetrahydrofuran polyether epoxy resin and bisphenol A polyether epoxy resin respectively react with the unsaturated monocarboxylic acid, and the catalyst for the reaction is selected from one or more of benzyltrimethylammonium chloride, triphenylphosphine, benzyltriethylammonium chloride, and benzyltriethylammonium bromide; the catalyst is more preferably triphenylphosphine. In the present invention, the weight percentage of the catalyst in the raw materials is preferably 0.24% - 0.25%. A polymerization inhibitor can also be added to the above reaction, and the polymerization inhibitor is preferably selected from one or more of hydroquinone, p-benzoquinone, tert-butylhydroquinone, 2,6-ditert-butyl-4-cresol, methylhydroquinone, and p-methoxyphenol; the polymerization inhibitor is more preferably methylhydroquinone. In the present invention, the weight percentage of the polymerization inhibitor in the raw materials is preferably 0.02% - 0.03%.

[0093] In the present invention, the isocyanate reacts with tetrahydrofuran polyether to form a diisocyanate polyether resin with an isocyanate group at the end group, and the flexible segment and cyano group further improve the wear resistance and the adhesion to carbon fiber. The diisocyanate polyether resin with an isocyanate group at the end group has a structure shown in formula (Ⅲ):

[0094]

[0095] Among them, R3 is selected from one or more of the following structures:

[0096]

[0097] n3 is any integer from 1 to 3, such as 1, 2, 3.

[0098] In the present invention, the molar ratio of isocyanate to tetrahydrofuran polyether is 2:1 - 5:1, and the more preferably molar ratio is 2:1 - 3:1. In some preferred embodiments of the present invention, using a linear isocyanate with a high isocyanate group content (such as an NCO content of more than 45%) to react with a high molecular weight (such as a molecular weight of more than 650) tetrahydrofuran polyether can further increase the number of wear resistance times of the carbon fiber vinyl resin composite material, indicating that reducing the content of the benzene ring rigid structure can effectively improve the wear resistance.

[0099] In the present invention, the isocyanate is preferably one or more of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate; more preferably 4,4-diphenylmethane diisocyanate or hexamethylene diisocyanate. In the present invention, the weight percentage of the isocyanate in the raw materials is preferably 3.5 - 10.9; in some specific embodiments of the present invention, the weight percentage of the isocyanate in the raw materials is 10.87%, 6.33%, 6.30%, 6.85%, 3.98%.

[0100] In the present invention, the structure of the tetrahydrofuran polyether is shown in the following formula, wherein n3 is any integer from 1 to 3, such as 1, 2, and 3. In the present invention, the molecular weight of the tetrahydrofuran polyether is preferably 200 to 800; more preferably 250. In the present invention, the weight percentage of the tetrahydrofuran polyether in the raw material is preferably 2.0% to 7.7%; in some specific embodiments of the present invention, the weight percentage of the tetrahydrofuran polyether in the raw material is 4.85%, 2.82%, 2.81%, 3.06%, and 7.69%.

[0101]

[0102] In the present invention, a diisocyanate polyether resin having an isocyanate terminal group and a vinyl resin prepolymer having an unsaturated carbon-carbon double bond terminal group are reacted, and the isocyanate reacts with the hydroxyl group obtained after the ring-opening of the epoxy group to obtain an isocyanate-modified vinyl resin prepolymer.

[0103] In the present invention, the isocyanate-modified vinyl resin prepolymer is mixed with carbon nanotubes, and an emulsifier is added. The carbon nanotubes are multi-walled, regular hexagonal, with an outer diameter of several nanometers to tens of nanometers, a length of micrometer level, and a carbon fiber diameter of 5 to 10 micrometers. The carbon nanotubes are uniformly dispersed in the isocyanate-modified vinyl resin prepolymer, baked at high temperature to form a film, and applied to the surface of the carbon fiber. The carbon nanotubes are used to increase the surface roughness of the carbon fiber and increase the specific surface area, thereby improving the interface performance of the sizing agent, the carbon fiber, and the resin matrix. Further preferably, the mass ratio of carbon nanotubes added is 0.5% to 1.5%, and in a further preferred embodiment, the addition amounts are 0.8% and 1.2%, respectively. In the present invention, the carbon nanotubes are preferably carbon nanotubes Tube M204.

[0104] In the present invention, the resistivity of the deionized water is preferably greater than 0.5MΩ·cm. In the present invention, the weight ratio of the deionized water in the raw material is preferably 39.0% to 40.0%; in some specific embodiments of the present invention, the weight ratio of the deionized water in the raw material is 39.80%, 39.92%, or 40.00%.

[0105] In the present invention, the emulsifier is an anionic emulsifier, and the emulsifier is preferably selected from one of alkylbenzene sulfonate, alkylnaphthalene sulfonate, alkyl sulfonate, alkylphenol polyoxyethylene ether sulfate, and aralkylphenol polyoxyethylene ether sulfate; preferably, the emulsifier is alkylphenol polyoxyethylene ether sulfate. In the present invention, the weight ratio of the emulsifier in the raw material is preferably 2.5% to 3.0%; in some specific embodiments of the present invention, the weight ratio of the emulsifier in the raw material is preferably 2.99%, 3%.

[0106] The present invention also provides a method for preparing the above vinyl carbon fiber sizing agent composition, comprising the following steps:

[0107] S1, Put tetrahydrofuran polyether epoxy resin and bisphenol A polyether epoxy resin into a reactor, add a polymerization inhibitor and an unsaturated monocarboxylic acid, stir for 10 - 15 minutes, heat up to 90 ± 2 °C, add a catalyst, maintain a heating rate of 6 - 8 °C / h, and heat up to 120 ± 2 °C. Continuously react until the acid value reaches 10 ± 3 mgKOH / g to obtain a vinyl resin prepolymer with unsaturated double bonds at the end groups; the vinyl resin prepolymer with unsaturated double bonds at the end groups includes tetrahydrofuran polyether vinyl resin with unsaturated carbon-carbon double bonds at the end groups and bisphenol A polyether vinyl resin with unsaturated carbon-carbon double bonds at the end groups;

[0108] Reaction 1a: Generate tetrahydrofuran polyether vinyl resin with unsaturated carbon-carbon double bonds at the end groups

[0109]

[0110]

[0111] Among them, R2 is H or CH3; n1 is any integer from 1 to 4.

[0112] Reaction 1b: Generate bisphenol A polyether vinyl resin with unsaturated carbon-carbon double bonds at the end groups

[0113]

[0114] Among them, R1 is H or CH3; n2 is any integer from 1 to 3.

[0115] S2, Put the isocyanate into another reactor, heat up to 45 ± 2 °C, dropwise add tetrahydrofuran polyether, and continuously react until the hydroxyl value is 0 mgKOH / g to obtain a diisocyanate resin with isocyanate groups at the end groups.

[0116]

[0117] n3 = 1 - 3; R3 is one or more of the following structures:

[0118]

[0119] S3, Lower the temperature of the reactor containing the vinyl resin prepolymer with unsaturated double bonds at the end groups to 60 ± 2 °C, add the diisocyanate resin with isocyanate groups at the end groups prepared in S2 into the reactor and continue to react until the isocyanate group content is 0 to obtain an isocyanate-modified vinyl resin prepolymer.

[0120]

[0121] Among them, R4 is selected from one or two of the following structures:

[0122]

[0123] The structure of R5 is as follows:

[0124]

[0125] S4 puts the isocyanate-modified vinyl resin prepolymer prepared by S3 into an emulsification reactor, heats up to 65 ± 2 °C, adds an emulsifier, stirs for 10 - 15 minutes, adds carbon nanotubes, continues to stir for 10 - 15 minutes, drops in deionized water, and maintains the reactor temperature at 65 ± 5 °C; when 30% of the deionized water has been dropped in, stop dropping the deionized water, stir for 60 ± 5 minutes, then add the remaining deionized water, and stir for 60 ± 5 minutes to obtain a carbon nanotube-modified vinyl carbon fiber sizing agent.

[0126] The technical solutions provided by the present invention will be described in detail below in conjunction with the embodiments, but they cannot be understood as limiting the protection scope of the present invention. For the experimental methods without specific conditions noted in the following embodiments, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. All raw materials without the noted synthesis method are purchased from the market.

[0127] Example 1

[0128] Put 1050 g of tetrahydrofuran polyether epoxy resin (1 mol, molecular weight 1050 g / mol) and 667 g of bisphenol A polyether epoxy resin (1 mol, molecular weight 667 g / mol) into a reactor, add 1.55 g of methylhydroquinone and 344 g of methacrylic acid (4 mol), stir for 10 - 15 minutes, heat up to 90 ± 2 °C, add 12.9 g of triphenylphosphine, maintain a heating rate of 6 - 8 °C / h, and heat up to 120 ± 2 °C. Continue the reaction until the acid value reaches 10 ± 3 mg KOH / g to obtain a vinyl resin prepolymer with unsaturated double bonds at the end groups.

[0129] Put 560 g of 4,4-diphenylmethane diisocyanate (MM 103C, NCO content 29.0% - 30.0%) into another reactor, heat up to 45 ± 2 °C, drop in 250 g of tetrahydrofuran polyether (1 mol, molecular weight 250 g / mol), and continue the reaction until the hydroxyl value is 0 mg KOH / g to obtain a diisocyanate resin with isocyanate groups at the end groups.

[0130] Lower the temperature of the reactor containing the vinyl resin prepolymer to 60 ± 2 °C, put the diisocyanate resin prepared in the previous step into the reactor and continue the reaction, control the reaction temperature at 60 ± 2 °C until the isocyanate group content is 0 to obtain an isocyanate-modified vinyl resin prepolymer.

[0131] Put the vinyl resin prepolymer prepared in the previous step into an emulsification reactor, heat it up to 65 ± 2 °C, add 154.6 alkylphenol polyoxyethylene ether sulfate emulsifier, stir for 10 - 15 minutes, add 51.5 g of carbon nanotubes (TubeM204), continue to stir for 10 - 15 minutes, then drip deionized water while maintaining the reactor temperature at 65 ± 5 °C. When the deionized water is dripped to 618.3 g, stop dripping deionized water, stir for 60 ± 5 minutes, and then add 1442.7 g of deionized water and stir for 60 ± 5 minutes to obtain a carbon nanotube-modified vinyl carbon fiber sizing agent.

[0132] Example 2

[0133] Put 1050 g of tetrahydrofuran polyether epoxy resin (1 mol, molecular weight 1050 g / mol) and 667 g of bisphenol A polyether epoxy resin (1 mol, molecular weight 667 g / mol) into a reactor, add 1.32 g of methylhydroquinone and 344 g of methacrylic acid (4 mol), stir for 10 - 15 minutes, heat up to 90 ± 2 °C, add 11.1 g of triphenylphosphine, maintain a heating rate of 6 - 8 °C / h, and heat up to 120 ± 2 °C. Continue the reaction until the acid value reaches 10 ± 3 mgKOH / g to obtain a vinyl resin prepolymer with unsaturated double bonds at the end groups.

[0134] Put 280 g of 4,4-diphenylmethane diisocyanate (MM 103C, NCO content 29.0 - 30.0%) into another reactor, heat it up to 45 ± 2 °C, drip 125 g of tetrahydrofuran polyether (0.5 mol, molecular weight 250 g / mol), and continue the reaction until the hydroxyl value is 0 mgKOH / g to obtain a diisocyanate resin with isocyanate groups at the end groups.

[0135] Lower the temperature of the reactor containing the vinyl resin prepolymer to 60 ± 2 °C, put the diisocyanate resin prepared in the previous step into the reactor and continue the reaction, control the reaction temperature at 60 ± 2 °C until the isocyanate group content is 0 to obtain an isocyanate-modified vinyl resin prepolymer.

[0136] Put the vinyl resin prepolymer prepared in the previous step into an emulsification reactor, heat it up to 65 ± 2 °C, add 132.8 alkylphenol polyoxyethylene ether sulfate emulsifier, stir for 10 - 15 minutes, add 44.2 g of carbon nanotubes (TubeM204), continue to stir for 10 - 15 minutes, then drip deionized water while maintaining the reactor temperature at 65 ± 5 °C. When the deionized water is dripped to 531.1 g, stop dripping deionized water, stir for 60 ± 5 minutes, and then add 1239.2 g of deionized water and stir for 60 ± 5 minutes to obtain a carbon nanotube-modified vinyl carbon fiber sizing agent.

[0137] Example 3

[0138] Put 1050 g of tetrahydrofuran polyether epoxy resin (1 mol, molecular weight 1050 g / mol) and 667 g of bisphenol A polyether epoxy resin (1 mol, molecular weight 667 g / mol) into a reactor, add 1.32 g of methylhydroquinone and 344 g of methacrylic acid (4 mol), stir for 10 - 15 minutes, heat up to 90 ± 2 °C, add 11.1 g of triphenylphosphine, maintain a heating rate of 6 - 8 °C / h, and heat up to 120 ± 2 °C. Continue the reaction until the acid value reaches 10 ± 3 mgKOH / g to obtain a vinyl resin prepolymer with unsaturated double bonds at the end groups.

[0139] Put 280 g of 4,4-diphenylmethane diisocyanate (MM 103C, NCO content 29.0 - 30.0%) into another reactor, heat up to 45 ± 2 °C, dropwise add 125 g of tetrahydrofuran polyether (0.5 mol, molecular weight 250 g / mol), and continue the reaction until the hydroxyl value is 0 mgKOH / g to obtain a diisocyanate resin with isocyanate groups at the end groups.

[0140] Lower the temperature of the reactor containing the vinyl resin prepolymer to 60 ± 2 °C, put the diisocyanate resin prepared in the previous step into the reactor and continue the reaction, control the reaction temperature at 60 ± 2 °C until the isocyanate group content is 0 to obtain an isocyanate-modified vinyl resin prepolymer.

[0141] Put the vinyl resin prepolymer prepared in the previous step into an emulsification reactor, heat up to 65 ± 2 °C, add 132.8 g of alkylphenol polyoxyethylene ether sulfate emulsifier, stir for 10 - 15 minutes, add 66.3 g of carbon nanotubes (TubeM204), continue to stir for 10 - 15 minutes, dropwise add deionized water, and maintain the reactor temperature at 65 ± 5 °C. When the deionized water is added up to 531.1 g, stop adding deionized water, stir for 60 ± 5 minutes, then add 1239.2 g of deionized water, and stir for 60 ± 5 minutes to obtain a carbon nanotube-modified vinyl carbon fiber sizing agent.

[0142] The difference between Example 3 and Example 2 is that the proportion of carbon nanotubes is increased to 1.2%.

[0143] Example 4

[0144] Put 525 g of tetrahydrofuran polyether epoxy resin (0.5 mol, molecular weight 1050 g / mol) and 1000 g of bisphenol A polyether epoxy resin (1.5 mol, molecular weight 667 g / mol) into a reactor, add 1.22 g of methylhydroquinone and 344 g of methacrylic acid (4 mol), stir for 10 - 15 minutes, heat up to 90 ± 2 °C, add 10.2 g of triphenylphosphine, maintain a heating rate of 6 - 8 °C / h, and heat up to 120 ± 2 °C. Continuously react until the acid value reaches 10 ± 3 mgKOH / g to obtain a vinyl resin prepolymer with unsaturated double bonds at the end groups.

[0145] Put 280 g of 4,4-diphenylmethane diisocyanate (MM 103C, NCO content 29.0 - 30.0%) into another reactor, heat up to 45 ± 2 °C, and dropwise add 125 g of tetrahydrofuran polyether (0.5 mol, molecular weight 250 g / mol). Continuously react until the hydroxyl value is 0 mgKOH / g to obtain a diisocyanate resin with isocyanate groups at the end groups.

[0146] Lower the temperature of the reactor containing the vinyl resin prepolymer to 60 ± 2 °C, put the diisocyanate resin prepared in the previous step into the reactor and continue the reaction, control the reaction temperature at 60 ± 2 °C until the isocyanate group content is 0 to obtain an isocyanate-modified vinyl resin prepolymer.

[0147] Put the vinyl resin prepolymer prepared in the previous step into an emulsification reactor, heat up to 65 ± 2 °C, add 122.4 g of alkylphenol polyoxyethylene ether sulfate emulsifier, stir for 10 - 15 minutes, add 48.9 g of carbon nanotubes (TubeM204), continue to stir for 10 - 15 minutes, dropwise add deionized water, and maintain the reactor temperature at 65 ± 5 °C. When the deionized water is added up to 489.7 g, stop adding deionized water, stir for 60 ± 5 minutes, then add 1142.7 g of deionized water, and stir for 60 ± 5 minutes to obtain a carbon nanotube-modified vinyl carbon fiber sizing agent.

[0148] The difference between Example 4 and Example 3 is that the molar ratio of tetrahydrofuran polyether epoxy resin to bisphenol A polyether epoxy resin is adjusted from 1:1 to 1:3.

[0149] Example 5

[0150] Put 525 g of tetrahydrofuran polyether epoxy resin (0.5 mol, molecular weight 1050 g / mol) and 1000 g of bisphenol A polyether epoxy resin (1.5 mol, molecular weight 667 g / mol) into a reactor, add 1.27 g of methylhydroquinone and 344 g of methacrylic acid (4 mol), stir for 10 - 15 minutes, heat up to 90 ± 2 °C, add 10.2 g of triphenylphosphine, maintain a heating rate of 6 - 8 °C / h, and heat up to 120 ± 2 °C. Continue the reaction until the acid value reaches 10 ± 3 mgKOH / g to obtain a vinyl resin prepolymer with unsaturated double bonds at the end groups.

[0151] Put 168 g of hexamethylene diisocyanate (NCO content 49.0 - 50.0%) into another reactor, heat up to 45 ± 2 °C, and dropwise add 325 g of tetrahydrofuran polyether (0.5 mol, molecular weight 650 g / mol). Continue the reaction until the hydroxyl value is 0 mgKOH / g to obtain a diisocyanate resin with isocyanate groups at the end groups.

[0152] Lower the temperature of the reactor containing the vinyl resin prepolymer to 60 ± 2 °C, put the diisocyanate resin prepared in the previous step into the reactor and continue the reaction, control the reaction temperature at 60 ± 2 °C until the isocyanate group content is 0 to obtain an isocyanate-modified vinyl resin prepolymer.

[0153] Put the vinyl resin prepolymer prepared in the previous step into an emulsification reactor, heat up to 65 ± 2 °C, add 126.7 alkylphenol polyoxyethylene ether sulfate emulsifier, stir for 10 - 15 minutes, add 33.8 g of carbon nanotubes (TubeM204), continue to stir for 10 - 15 minutes, and dropwise add deionized water while maintaining the reactor temperature at 65 ± 5 °C. When the deionized water is added up to 506.9 g, stop adding deionized water, stir for 60 ± 5 minutes, and then add 1182.7 g of deionized water and stir for 60 ± 5 minutes to obtain a carbon nanotube-modified vinyl carbon fiber sizing agent.

[0154] Comparative Example 1

[0155] Put 684 g of propylene glycol into a reaction kettle, heat up to 100 ± 2 °C, add 747 g of phthalic acid, stir for 30 min, heat up to 210 °C, test that the acid value is less than 10 mgKOH / g, and terminate the first-step reaction. Cool down to 160 °C, add 432 g of maleic anhydride, test that the acid value reaches 10 - 16 mgKOH / g, and prepare an unsaturated polyester resin.

[0156] Put the unsaturated polyester resin prepared in the previous step into an emulsification reactor, heat it up to 65 ± 2 °C, add 126.7 alkylphenol polyoxyethylene ether sulfate emulsifier, stir for 10 - 15 minutes, add 33.8 g of carbon nanotubes (Tube M204), continue to stir for 10 - 15 minutes, and then dropwise add deionized water while maintaining the reactor temperature at 65 ± 5 °C. When the deionized water is added up to 506.9 g, stop adding deionized water, stir for 60 ± 5 minutes, and then add 1182.7 g of deionized water and stir for 60 ± 5 minutes to obtain a sizing agent for carbon nanotube-modified unsaturated polyester resin.

[0157] Experimental Example

[0158] Use the sizing agents for carbon nanotube-modified vinyl carbon fibers obtained in Examples 1 - 5 above and the sizing agent for carbon nanotube-modified unsaturated polyester resin prepared in Comparative Example 1 to prepare carbon fibers, and then use the pultrusion process to prepare carbon fiber composites. Test the abrasion resistance times of carbon fibers, the sizing amount of carbon fibers, the short beam interlaminar shear strength of carbon fiber composites, and the retention rate after boiling in water (seawater). The test results are shown in Table 1;

[0159] Method for preparing carbon fibers: The carbon fibers are wound around a roller and enter a sizing tank for sizing, then enter an oven for baking. The oven temperature is 150 °C to remove moisture, and then they are prepared into carbon fibers through a winding process. The sizing amount of carbon fibers is 1.2 - 1.5%.

[0160] The specifications of the carbon fibers: 12KT700 carbon fibers;

[0161] Method for preparing carbon fiber composites by pultrusion process: The carbon fibers pass through an impregnation tank and enter a mold. The impregnation tank is filled with epoxy vinyl ester resin. The cross-sectional size of the mold is 100 mm * 4 mm, and the length of the mold is 90 cm. The temperatures of the three zones are 120 °C, 150 °C, and 140 °C respectively, and carbon fiber composites are prepared through a traction mechanism.

[0162] The epoxy vinyl ester resin: MERICAN 30 - 900 epoxy vinyl ester resin

[0163] Test for the abrasion resistance times of carbon fibers: Refer to the reciprocating roller method in the yarn abrasion test method FZT01058, make a self-made abrasion test instrument, with a 50 g weight, 120 r / min, and coated with 600 - mesh sandpaper. The number of movements when the fiber breaks is recorded as the abrasion resistance times.

[0164] The sizing amount of carbon fibers is tested according to the test method for the sizing agent content of carbon fibers in Appendix B of GB / T 26752 - 2011 polyacrylonitrile carbon fibers.

[0165] The short beam interlaminar shear strength of carbon fiber composites is carried out according to ISO 14130.

[0166] Retention rate test of carbon fiber composite material boiled in water (seawater): Prepare the carbon fiber composite material into bending splines according to GB / T 1449-2005. Then, put a part of the bending splines into a reaction flask filled with seawater at 98 °C and boil for 2 h. After taking them out, let them cool naturally, and use absorbent paper to remove the surface moisture. Place them in a laboratory environment at 23±2 °C. After 24 h, test the bending strength according to GB / T1449-2005. The ratio of the bending strength after boiling in water to the bending strength before boiling in water is recorded as the retention rate of the carbon fiber composite material boiled in water (seawater).

[0167] Table 1 Test results of Examples 1-5

[0168]

[0169] As can be seen from Table 1:

[0170] 1. Compared with Comparative Example 1, the wear resistance times of the carbon fiber composite materials prepared with the sizing agents of Examples 1-5 are significantly improved. Compared with Comparative Example 1, the interlaminar shear strength of the carbon fiber composite materials prepared with the sizing agents of Examples 1-5 is significantly improved. The film-forming agent of Comparative Example 1 is unsaturated polyester resin, with a high ratio of unsaturated double bonds and benzene rings and poor wear resistance, so the wear resistance times are low. In addition, although carbon nanotubes are used in the comparative example, the unsaturated polyester resin lacks polar groups and has poor interfacial bonding with the fiber, so the interlaminar shear strength is lower than that of Examples 1-5.

[0171] 2. Example 5 uses linear hexamethylene diisocyanate and high molecular weight tetrahydrofuran polyether, with the highest wear resistance times reaching 112 times, indicating that reducing the content of the rigid benzene ring structure can further effectively improve the wear resistance times;

[0172] 3. By increasing the content of carbon nanotubes in Example 3, the interlaminar shear strength can be further improved. On this basis, increasing or decreasing the proportion of tetrahydrofuran polyether epoxy resin will result in a decrease in the interlaminar shear performance.

[0173] 4. Compared with the examples, the retention rate of Comparative Example 1 boiled in water has decreased significantly. The main reason is that 1 mol of the sizing agent in Comparative Example 1 contains 10-12 mol of ester groups, and 1 mol of the example contains 2-4 mol of ester groups. Their molecular weights are comparable, and the high density of ester groups leads to a decrease in the retention rate of boiling in water.

[0174] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A sizing agent composition for vinyl carbon fiber modified by carbon nanotubes, characterized in that, It includes an isocyanate-modified vinyl resin prepolymer and carbon nanotubes; each mole of the isocyanate-modified vinyl resin prepolymer contains 2 to 4 moles of ester groups; The isocyanate-modified vinyl resin prepolymer is obtained by reacting a vinyl resin prepolymer with an unsaturated carbon-carbon double bond at the end and a diisocyanate polyether resin with an isocyanate group at the end; The vinyl resin prepolymer with an unsaturated carbon-carbon double bond at the end includes a tetrahydrofuran polyether vinyl resin with an unsaturated carbon-carbon double bond at the end and a bisphenol A polyether vinyl resin with an unsaturated carbon-carbon double bond at the end; The tetrahydrofuran polyether vinyl resin with an unsaturated carbon-carbon double bond at the end is obtained by reacting a tetrahydrofuran polyether epoxy resin with an unsaturated monocarboxylic acid; the tetrahydrofuran polyether epoxy resin is formed by the etherification and cyclization reactions of tetrahydrofuran polyether, epichlorohydrin, and sodium hydroxide; The isocyanate-modified vinyl resin prepolymer has a structure shown in formula (Ⅳ): Among them, R4 is selected from the following structures: The structure of R5 is: R1 is H or CH3; n2 is any integer from 1 to 3; R2 is H or CH3; n1 is any integer from 1 to 4; R3 is selected from one or more of the following structures: n3 is any integer from 1 to 3.

2. The sizing agent composition for vinyl carbon fiber modified by carbon nanotubes according to claim 1, characterized in that, The molar ratio of the tetrahydrofuran polyether vinyl resin with an unsaturated carbon-carbon double bond at the end to the bisphenol A polyether vinyl resin with an unsaturated carbon-carbon double bond at the end is 1:5 to 5:

1.

3. The sizing agent composition for vinyl carbon fiber modified by carbon nanotubes according to claim 2, wherein, The molar ratio of the tetrahydrofuran polyether vinyl resin with an unsaturated carbon-carbon double bond at the end to the bisphenol A polyether vinyl resin with an unsaturated carbon-carbon double bond at the end is 1:1 to 1:

3.

4. The sizing agent composition for vinyl carbon fiber modified by carbon nanotubes according to claim 1, characterized in that, The tetrahydrofuran polyether vinyl resin with an unsaturated carbon-carbon double bond at the end has a structure shown in formula (Ⅰ): Among them, R2 is H or CH3; n1 is any integer from 1 to 4.

5. The sizing agent composition for vinyl carbon fiber modified by carbon nanotubes according to claim 4, wherein, R2 is CH3; n1 is 2.

6. The sizing agent composition for vinyl carbon fiber modified by carbon nanotubes according to claim 1, characterized in that, The bisphenol A polyether vinyl resin with an unsaturated carbon-carbon double bond at the end has a structure shown in formula (Ⅱ): Among them, R1 is H or CH3; n2 is any integer from 1 to 3.

7. The sizing agent composition for vinyl carbon fiber modified by carbon nanotubes according to claim 6, characterized in that, R1 is CH3; n2 is 3.

8. The sizing agent composition for vinyl carbon fiber modified with carbon nanotubes according to claim 6, characterized in that, The bisphenol A polyether vinyl resin with an unsaturated carbon-carbon double bond at the end is obtained by reacting a bisphenol A polyether epoxy resin with an unsaturated monocarboxylic acid.

9. The sizing agent composition for vinyl carbon fiber modified by carbon nanotubes according to claim 1, wherein The diisocyanate polyether resin with an isocyanate group at the end has a structure shown in formula (Ⅲ): Among them, R3 is selected from one or more of the following structures: n3 is any integer from 1 to 3.

10. The sizing agent composition for vinyl carbon fiber modified by carbon nanotubes according to claim 9, characterized in that, The diisocyanate polyether resin with an isocyanate group at the end is obtained by the ring-opening reaction of an isocyanate with a tetrahydrofuran polyether.

11. The sizing agent composition for vinyl carbon fiber modified by carbon nanotubes according to any one of claims 1 to 10, characterized in that, The sizing agent composition is made from raw materials including the following weight percentages:

12. The sizing agent composition for vinyl carbon fiber modified by carbon nanotubes according to claim 11, characterized in that, The sizing agent composition is made from raw materials including the following weight percentages:

13. The sizing agent composition for vinyl carbon fiber modified with carbon nanotubes according to claim 11, wherein, The molecular weight of the tetrahydrofuran polyether epoxy resin is 800 to 1200; And / or, the molecular weight of the bisphenol A polyether epoxy resin is 500 to 700; And / or, the unsaturated monocarboxylic acid is selected from acrylic acid and / or methacrylic acid; And / or, the isocyanate is selected from one or more of isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate; And / or, the molecular weight of the tetrahydrofuran polyether is 200 to 800; And / or, the catalyst is selected from one or more of benzyltrimethylammonium chloride, triphenylphosphine, benzyltriethylammonium chloride, and benzyltriethylammonium bromide; And / or, the inhibitor is selected from one or more of hydroquinone, benzoquinone, tert-butylhydroquinone, 2,6-di-tert-butyl-4-methylphenol, methylhydroquinone, and p-methoxyphenol; And / or, the carbon nanotubes are multi-walled carbon nanotubes with an outer diameter of 1-99 nm; And / or, the resistivity of the deionized water is greater than 0.5 MΩ·cm; And / or, the emulsifier is an anionic emulsifier, and the emulsifier is selected from one or more of alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkylphenol polyoxyethylene ether sulfates, and aralkylphenol polyoxyethylene ether sulfates.

14. A method for preparing a sizing agent composition for vinyl carbon fiber modified by carbon nanotubes according to any one of claims 1-13, characterized in that, It includes the following steps: S1. Mix tetrahydrofuran polyether epoxy resin, bisphenol A polyether epoxy resin, inhibitor, and unsaturated monocarboxylic acid, add the catalyst at 90°C - 120°C, and continuously react until the acid value reaches 10 ± 3 mgKOH / g to obtain a vinyl resin prepolymer with terminal unsaturated carbon-carbon double bonds; The vinyl resin prepolymer with terminal unsaturated carbon-carbon double bonds includes tetrahydrofuran polyether vinyl resin with terminal unsaturated carbon-carbon double bonds and bisphenol A polyether vinyl resin with terminal unsaturated carbon-carbon double bonds; S2. At 40°C - 50°C, dropwise add tetrahydrofuran polyether to isocyanate, and continuously react until the hydroxyl value is 0 mgKOH / g to obtain a diisocyanate polyether resin with terminal isocyanate groups; S3. Add the diisocyanate polyether resin with terminal isocyanate groups to the vinyl resin prepolymer at 55°C - 60°C, and the isocyanate groups of the diisocyanate polyether resin react with the hydroxyl groups obtained by the ring-opening of the epoxy groups in the vinyl resin prepolymer, and continue to react until the isocyanate groups are 0 to obtain an isocyanate-modified vinyl resin prepolymer; S4. At 60 - 70°C, sequentially add an emulsifier, carbon nanotubes, and deionized water to the isocyanate-modified vinyl resin prepolymer to obtain a carbon nanotube-modified vinyl carbon fiber sizing agent; There is no order limit for steps S1 and S2.

15. The preparation method according to claim 14, wherein, In step S1, the molar ratio of tetrahydrofuran polyether epoxy resin to bisphenol A polyether epoxy resin is 1:5 - 5:1; And / or, the tetrahydrofuran polyether epoxy resin is formed by the etherification and cyclization reactions of tetrahydrofuran polyether, epichlorohydrin, and sodium hydroxide, with a molecular weight of 400 - 1600; And / or, the polyether group in the bisphenol A polyether epoxy resin is an ether bond structure introduced by polypropylene glycol or polyethylene glycol, with a molecular weight of 250 - 750; And / or, the unsaturated monocarboxylic acid is selected from acrylic acid and / or methacrylic acid; And / or, the inhibitor is selected from one or more of hydroquinone, benzoquinone, tert-butylhydroquinone, 2,6-di-tert-butyl-4-methylphenol, methylhydroquinone, and p-methoxyphenol.

16. The preparation method according to claim 15, characterized in that, The molar ratio of tetrahydrofuran polyether epoxy resin to bisphenol A polyether epoxy resin is 1:1 - 1:

3.

17. The preparation method according to claim 14 or 15, characterized in that, Step S1 is as follows: Mix tetrahydrofuran polyether epoxy resin, bisphenol A polyether epoxy resin, inhibitor and unsaturated monocarboxylic acid, stir for 10 - 15 min, add a catalyst at 90 °C, heat up to 120 °C at a rate of 6 °C - 8 °C / h, and continue the reaction until the acid value reaches 10 ± 3 mgKOH / g to obtain a vinyl resin prepolymer with unsaturated carbon-carbon double bonds at the end groups.

18. The preparation method according to claim 14, characterized in that, The reaction temperature of step S2 is 45 °C ± 2 °C; and / or, the reaction temperature of step S3 is 60 °C ± 2 °C; and / or, the isocyanate is selected from one or more of isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate; and / or, the molecular weight of the tetrahydrofuran polyether is 200 - 800; and / or, the emulsifier is an anionic emulsifier, and the emulsifier is selected from one or more of alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkyl sulfonates, alkylphenol polyoxyethylene ether sulfates, and aralkylphenol polyoxyethylene ether sulfates; and / or, the carbon nanotube is a multi-walled carbon nanotube with an outer diameter of 1 - 99 nm; and / or, the resistivity of deionized water is greater than 0.5 MΩ·cm; and / or, the reaction temperature of step S4 is 65 °C ± 2 °C.

19. The preparation method according to claim 14 or 18, characterized in that, Step S4 is as follows: At 65 °C ± 2 °C, add an emulsifier to the isocyanate-modified vinyl resin prepolymer, stir for 10 - 15 minutes, then add carbon nanotubes, continue to stir for 10 - 15 minutes, add 30% by mass of deionized water, continue to stir for 55 - 65 minutes, add the remaining deionized water, and continue to stir for 55 - 65 minutes to obtain a carbon nanotube-modified vinyl carbon fiber sizing agent.

20. Application of the carbon nanotube-modified vinyl carbon fiber sizing agent composition according to any one of claims 1 - 13 or the carbon nanotube-modified vinyl carbon fiber sizing agent composition obtained by the preparation method according to any one of claims 14 - 19 in the preparation of a carbon fiber vinyl resin composite suitable for a marine environment.

21. A carbon fiber vinyl ester resin composite suitable for marine environments, characterized in that, It sequentially includes a carbon fiber, the carbon nanotube-modified vinyl carbon fiber sizing agent composition according to any one of claims 1 - 13, and a vinyl resin matrix from the inside to the outside.

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