Sizing agent for carbon fibers, carbon fiber bundle and carbon fiber reinforced composite material

Abstract

The invention discloses a sizing agent for carbon fibers, a carbon fiber bundle and a carbon fiber reinforced composite material, and relates to the technical field of carbon fibers. The sizing agent for the carbon fibers comprises a first component and a second component, the first component is a compound with at least one epoxy group in molecules, and the second component is waterborne polyurethane resin with an anionic hydrophilic group I and a nonionic hydrophilic group II which take ammonium ions as counter ions in molecules at the same time. Wherein the anionic hydrophilic group I is obtained by introducing a macromolecular skeleton and neutralizing the macromolecular skeleton with amine or ammonia to form ammonium carboxylate, the nonionic hydrophilic group II is obtained by introducing a macromolecular skeleton, and the weight ratio (II / I) of the anionic hydrophilic group I to the nonionic hydrophilic group II is 0.5-20. According to the sizing agent for the carbon fibers, the group II is introduced into macromolecules, the reaction activity of ammonium ions of the group I to epoxy groups in the first component can be reduced, and therefore the sizing agent for the carbon fibers has the advantages of being long in storage time, good in physical property retentivity, high in interface adhesion, excellent in technological operation performance and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon fibers, and in particular to a sizing agent for carbon fibers, a carbon fiber bundle, and a carbon fiber reinforced composite material. Background Art

[0002] Carbon fiber is a high-performance material with extremely high specific strength and modulus, fully meeting the demand for weight reduction in structural materials. Consequently, its application in numerous industrial sectors, including aerospace, rail transportation, surface vessels, wind power, pressure vessels, sports and leisure, and medical equipment, is increasing year by year. The application volume and market share of carbon fiber in various industrial sectors have become one of the most important indicators of the level of industrial technology and the civilian application of advanced technologies in that sector.

[0003] Carbon fiber is used in a variety of product forms, including bundles, fabrics, prepregs, and chopped carbon fibers. To truly realize its value, it must be combined with a matrix material to create composite components. Composite materials using carbon fiber as a reinforcing fiber can be made from a variety of matrix materials, including resins, metals, ceramics, carbon materials, and cement. Currently, composite materials based on resins account for over 80% of the market share, with epoxy-based resins holding a dominant position.

[0004] Carbon fiber is a brittle material with low elongation at break. During the process of being processed into carbon fiber products, it is easy to produce fuzz or even broken fibers due to mechanical friction. In addition, it lacks wettability to the matrix resin, making it difficult to give full play to its excellent mechanical properties. In order to solve the above problems, currently available carbon fibers are mostly sized with sizing agents using thermosetting resins (epoxy, phenolic, vinyl ester) as the main agent and thermoplastic resins (polyester, polyurethane, polyamide, polyolefin) as auxiliary agents. It is generally believed that the main agent can improve the wettability of carbon fiber products to the matrix resin and provide sufficient interfacial adhesion; the auxiliary agent is mostly used to give the fiber products certain process operability, such as bundling, fiber opening, and wear resistance. In addition, it can also provide the toughness required for the composite material interface.

[0005] When using the above-mentioned sizing agents to size carbon fibers, water is often used as a solvent to dissolve or disperse the above-mentioned sizing agents based on environmental protection, safety, and the health of operators. Emulsifiers can be used for dissolution or dispersion, and hydrophilic groups can be introduced into the macromolecular skeleton for dissolution or dispersion. At present, various carbon fiber manufacturers are similar in the choice of main agents, generally based on a mixture of solid epoxy resin and liquid epoxy resin. However, due to different processing methods and usage scenarios, the choice of auxiliary agents by various manufacturers varies greatly, and has even become its technical feature. Among them, water-based polyurethane resin has significant advantages in giving carbon fiber products good bundling and wear resistance, as well as in constructing a high-strength and high-toughness interfacial phase, and is an important auxiliary ingredient in the sizing agent.

[0006] When using waterborne polyurethane as an auxiliary agent in a sizing agent, from the perspective of storage stability, film-forming material properties, and economic considerations, an external emulsification method in which an emulsifier is added for dispersion is generally not used, but a self-emulsification method in which an anionic hydrophilic group of a carboxylate type or sulfonate type is introduced into the polyurethane segment for dispersion is adopted. In the case where the hydrophilic group is a sulfonate, since its counter ion is an alkali metal or alkaline earth metal, the introduction of the composite material will result in a reduction in thermal stability and should be avoided as much as possible. On the other hand, in the case where the hydrophilic group is a carboxylate, since its counter ion is an ammonium ion in most cases, it has a chemical activity that promotes the ring-opening reaction of the epoxy group in the main agent, so the storage time after mixing with the main agent is short, and the carbon fiber product hardens with increasing storage time after sizing, resulting in a deterioration in process processing performance, thereby reducing the mechanical properties of the composite material.

[0007] In view of this, the present invention is proposed. Summary of the Invention

[0008] The object of the present invention is to provide a sizing agent for carbon fiber, a carbon fiber bundle and a carbon fiber reinforced composite material. The carbon fiber sizing agent has the characteristics of long storage time, good physical property retention, strong interface bonding performance, excellent process operation performance, etc.

[0009] The present invention is achieved in that:

[0010] In a first aspect, the present invention provides a sizing agent for carbon fiber, comprising a first component and a second component, wherein the first component is a compound having at least one epoxy group in the molecule, and the second component is an aqueous polyurethane resin having both anionic hydrophilic group I and nonionic hydrophilic group II in the molecule with ammonium ion as a counter ion;

[0011] The anionic hydrophilic group I with ammonium ion as counter ion is obtained by reacting a chain extender containing a carboxyl group with a macromolecular skeleton composed of polyurethane segments, and then neutralizing with amine or ammonia to form ammonium carboxylate; the structure of the chain extender containing a carboxyl group is R1 is a hydrogen atom or a C1-C3 hydrocarbon group;

[0012] The nonionic hydrophilic group II is obtained by reacting a chain extender containing a nonionic hydrophilic group with a macromolecular skeleton composed of polyurethane segments; the structural formula of the chain extender containing a nonionic hydrophilic group is R2 is a hydrogen atom or a C1-C3 hydrocarbon group; R3 is a C1-C3 hydrocarbon group; AO is a C2-C4 alkyleneoxy group, m is the number average molar addition number of the alkyleneoxy group, m=4-60;

[0013] The weight ratio (II / I) of the nonionic hydrophilic group II to the anionic hydrophilic group I with ammonium ion as counter ion is 0.5-20.

[0014] In an optional embodiment, the weight ratio (II / I) of the nonionic hydrophilic group II to the anionic hydrophilic group I with ammonium ion as counter ion is 1 to 10, preferably 2 to 6;

[0015] And / or, R1 is any one of methyl and ethyl; R2 is methyl; R3 is methyl; AO is at least one of ethyleneoxy, propyleneoxy and butyleneoxy, and m=10-35.

[0016] In an optional embodiment, the carboxyl group-containing chain extender includes at least one of 2,2-dimethylol propionic acid, 2,2-dimethylol butyric acid and 2,2-dimethylol valeric acid;

[0017] And / or, the chain extender containing nonionic hydrophilic groups includes Ymer TM N180, Ymer TM N120 and Ymer TM At least one of the N90.

[0018] In an optional embodiment, the weight percentage of the first component in the non-volatile components is 20% to 99%, the weight percentage of the second component in the non-volatile components is 1% to 80%, and the weight percentage of the total weight of the anionic hydrophilic group I with ammonium ions as counterions and the non-ionic hydrophilic group II in the second component is 1% to 20%, preferably 3% to 10%.

[0019] In an optional embodiment, the first component is at least one of an epoxy resin and a modified epoxy resin;

[0020] Preferably, the epoxy resin includes glycidyl ether epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, heterocyclic epoxy resin and mixed epoxy resin, preferably glycidyl ether epoxy resin, more preferably bisphenol A epoxy resin and bisphenol F epoxy resin, most preferably bisphenol A epoxy resin;

[0021] Preferably, the modified epoxy resin includes at least one of a chemically modified epoxy resin and a physically modified epoxy resin; wherein the chemically modified epoxy resin includes (meth)acrylic acid modified, polyurethane modified, and polyethersulfone modified epoxy resins; and the physically modified epoxy resin includes resin blend modified and filler filled modified epoxy resins.

[0022] In an optional embodiment, the second component is a waterborne polyurethane resin obtained by condensation polymerization of a polyisocyanate, an oligomer polyol, a chain extender, a salt-forming agent, and a cross-linking agent, with water as the dispersion medium;

[0023] Preferably, the polyisocyanate comprises at least one of aromatic polyisocyanate, aromatic aliphatic polyisocyanate, aliphatic polyisocyanate, alicyclic polyisocyanate, cycloaliphatic polyisocyanate and polyisocyanate derivatives;

[0024] Preferably, the oligomer polyol includes at least one of a polyester oligomer polyol, a polyether oligomer polyol, and a polyester polyether oligomer polyol containing both a polyester structure and a polyether structure in the molecule;

[0025] Preferably, the chain extender includes the chain extender containing a carboxyl group, the chain extender containing a nonionic hydrophilic group and a supplementary chain extender, and the supplementary chain extender includes at least one of 1,4-butanediol, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, diethylene glycol, hexylene glycol, neopentyl glycol, 1,4-cyclohexanediol, bisphenol A and its alkylene oxide adduct, ethylenediamine, hydrazine, hexamethylenediamine, isophoronediamine and 3,3'-dichloro-4,4'-diphenylmethanediamine;

[0026] Preferably, the cross-linking agent comprises at least one of trimethylolethane, trimethylolpropane, pentaerythritol and diethylenetriamine;

[0027] Preferably, the salt-forming agent includes at least one of triethylamine, diethanolamine, triethanolamine and N,N-dimethylethanolamine.

[0028] In an optional embodiment, the carbon fiber sizing agent further comprises a surfactant as a fourth component, wherein the surfactant comprises at least one of a nonionic surfactant and an anionic surfactant;

[0029] Preferably, based on the weight percentage of non-volatile components, the first component is 30% to 80%, the second component is 5% to 50%, and the fourth component is 10% to 50%.

[0030] In an optional embodiment, the carbon fiber sizing agent further includes a third component, the third component including at least one of a vinyl ester resin and an unsaturated polyester resin, and the first component is 25% to 50%, the second component is 5% to 30%, the third component is 5% to 50%, and the fourth component is 15% to 30% by weight of the non-volatile component;

[0031] The vinyl ester resin is a resin oligomer with an aliphatic or aromatic organic compound as a skeleton and an end group or a side group being at least one of a vinyl ester group, an acrylate group and a methacrylate group;

[0032] The unsaturated polyester resin is obtained by condensation polymerization of unsaturated dibasic acid or acid anhydride, saturated dibasic acid or acid anhydride and diol, and is a resin oligomer containing both ester groups and non-aromatic unsaturated double bonds in the molecule;

[0033] Preferably, the vinyl ester resin comprises at least one of polyalkoxy glycol di(meth)acrylate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl-2-hydroxyethyl-phthalate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl-phthalate, neopentyl glycol (meth)acrylate benzoate, bisphenol A di(meth)acrylate, alkylene oxide-added bisphenol A di(meth)acrylate, bisphenol A diglycidyl ether (meth)acrylate adduct, and alkylene oxide-added bisphenol A diglycidyl ether (meth)acrylate adduct;

[0034] Preferably, the unsaturated dibasic acid or anhydride comprises at least one of maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, cis-hexadienedioic acid, trans-hexadienedioic acid, cis-methylbutenedioic acid and trans-methylbutenedioic acid;

[0035] Preferably, the saturated dibasic acid or anhydride comprises at least one of phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, nadic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, adipic acid and sebacic acid;

[0036] Preferably, the diol comprises at least one of ethylene glycol, 1,2-propylene glycol, diethylene glycol, neopentyl glycol, hydrogenated bisphenol A and alkylene oxide-added bisphenol A;

[0037] Preferably, the acid value of the unsaturated polyester resin is 37 to 140 mg KOH / g.

[0038] In a second aspect, the present invention provides a carbon fiber bundle, comprising a raw carbon fiber bundle and a carbon fiber sizing agent according to any one of the aforementioned embodiments, wherein the carbon fiber sizing agent is attached to the raw carbon fiber bundle;

[0039] Preferably, the carbon fiber bundle is a carbon fiber bundle formed by bundling 3K to 50K fiber monofilaments;

[0040] Preferably, the attached amount of the carbon fiber sizing agent is 0.1% to 20% of the total weight of the carbon fiber sizing agent and the raw carbon fiber bundle.

[0041] In a third aspect, the present invention provides a carbon fiber reinforced composite material comprising a matrix resin and the carbon fiber bundle as described in the above embodiment.

[0042] The present invention has the following beneficial effects:

[0043] The carbon fiber sizing agent provided by the present invention can reduce the reactivity of ammonium ions from the anionic hydrophilic group I with the epoxy groups of the first component by introducing a nonionic hydrophilic group II into the macromolecular skeleton of the second component, thereby significantly improving the storage stability of the compound sizing agent and suppressing the change in the physical properties of the sized carbon fiber products with increasing storage time, thereby improving the storage time, having good process performance, and high wettability to the matrix resin. By using the carbon fiber bundles treated with the sizing method of the present invention, a composite material with excellent mechanical properties can be obtained. DETAILED DESCRIPTION

[0044] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0045] The present invention provides a sizing agent for carbon fiber, which comprises a first component A and a second component B.

[0046] First Component A is a compound containing at least one epoxy group in its molecule. It can be an epoxy resin, a modified epoxy resin, or a mixture of the two. The term "epoxy group" in this invention refers to a three-membered ring consisting of two carbon atoms and one oxygen atom. First Component A improves the wettability of carbon fiber products to the matrix resin, and the epoxy groups in the molecule provide sufficient interfacial adhesion.

[0047] The above-mentioned epoxy resin is a general term for compounds having two or more epoxy groups in one molecule and being able to form a three-dimensional cross-linked network cured product in the presence of appropriate chemical reagents. The present invention lists some typical but non-limiting examples: glycidyl ether epoxy resins, glycidyl ester epoxy resins, glycidyl amine epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins, heterocyclic epoxy resins and mixed epoxy resins, preferably glycidyl ether epoxy resins, more preferably bisphenol A epoxy resins and bisphenol F epoxy resins, and most preferably bisphenol A epoxy resins.

[0048] The modified epoxy resin may be at least one of a chemically modified epoxy resin and a physically modified epoxy resin. Typical, but non-limiting, examples of chemically modified epoxy resins are listed herein, including (meth)acrylic acid-modified, polyurethane-modified, and polyethersulfone-modified epoxy resins. Typical, but non-limiting, examples of physically modified epoxy resins are also listed herein, including resin blending-modified, filler-modified, and other physically modified epoxy resins.

[0049] Preferably, the modified epoxy resin in the present invention is selected from (meth)acrylic acid modified epoxy resin and polyurethane modified epoxy resin, and more preferably (meth)acrylic acid modified epoxy resin.

[0050] As the first component A having at least one epoxy group in the molecule, epoxy resin is preferred from the viewpoint of improving interfacial adhesion.

[0051] In the sizing agent for carbon fiber of the present invention, the weight percentage of the first component A in the non-volatile components is 20% to 99%, preferably 30% to 80%.

[0052] The second component B is a waterborne polyurethane resin having both anionic hydrophilic group I with ammonium ion as counter ion and nonionic hydrophilic group II in the molecule.

[0053] Among them, the anionic hydrophilic group I with ammonium ion as counter ion is obtained by reacting a chain extender containing a carboxyl group with a macromolecular skeleton composed of polyurethane segments, and then neutralizing with amine or ammonia to form ammonium carboxylate; the structure of the chain extender containing a carboxyl group is R1 is a hydrogen atom or a C1-C3 hydrocarbon group, preferably, R1 is any one of a methyl group and an ethyl group;

[0054] The nonionic hydrophilic group II is obtained by reacting a chain extender containing a nonionic hydrophilic group with a macromolecular skeleton composed of polyurethane segments; the structural formula of the chain extender containing a nonionic hydrophilic group is R2 is a hydrogen atom or a C1-C3 hydrocarbon group, preferably, R2 is a methyl group; R3 is a C1-C3 hydrocarbon group, preferably, R3 is a methyl group; AO is a C2-C4 alkyleneoxy group, for example, AO can be at least one of ethyleneoxy, propyleneoxy and butyleneoxy, preferably, AO is at least one of ethyleneoxy and propyleneoxy; m is the number average molar addition number of alkyleneoxy groups, m=4-60, preferably m=10-35, more preferably m=15-25; m AOs can be the same type of alkyleneoxy groups or different types of alkyleneoxy groups. When AO is two or more alkyleneoxy groups, it can be a random combination, a block combination, or a combination of the two, preferably a single combination of ethyleneoxy groups, a block combination of ethyleneoxy groups and propyleneoxy groups, and more preferably a single combination of ethyleneoxy groups.

[0055] The weight ratio (II / I) of the nonionic hydrophilic group II to the anionic hydrophilic group I with ammonium ions as counterions is 0.5 to 20. When (II / I) is less than 0.5, the content of the nonionic hydrophilic group II is low, and its inhibitory effect on the reactivity of ammonium ions is difficult to achieve. When (II / I) is greater than 20, the second component B cannot be emulsified in water, or even if it is emulsified, the physical properties of the film-forming product will be significantly reduced, which will impair the process operability of the carbon fiber after sizing. The weight ratio (II / I) of the nonionic hydrophilic group II to the anionic hydrophilic group I with ammonium ions as counterions is preferably 1 to 10, and more preferably 2 to 6.

[0056] The total weight percentage of the anionic hydrophilic group I with ammonium ion as counter ion and the nonionic hydrophilic group II in the second component B is 1% to 20%, preferably 3% to 10%.

[0057] The carboxyl-containing chain extender is a compound having two primary hydroxyl groups and one carboxyl group within the molecule. By introducing this chain extender into the macromolecular backbone containing the terminal ends, it reacts with a salt-forming agent to form ionic groups, thereby imparting water dispersibility to the second component B. Examples of carboxyl-containing chain extenders include, but are not limited to, at least one of 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, and 2,2-dimethylolpentanoic acid, with 2,2-dimethylolpropionic acid and 2,2-dimethylolbutanoic acid being preferred, and 2,2-dimethylolpropionic acid being most preferred.

[0058] Chain extenders containing nonionic hydrophilic groups are compounds with two primary hydroxyl groups and one end-capped polyether structure within the molecule. By introducing this chain extender into the macromolecular backbone containing the end-capped hydroxyl groups, the second component B becomes water-dispersible and simultaneously inhibits the reactivity of the ammonium ions in the anionic hydrophilic group I with the epoxy groups in the first component A. Chain extenders containing nonionic hydrophilic groups include, but are not limited to, Ymer TM N180, YmerTM N120 and Ymer TM N90, preferably Ymer TM N120 and Ymer TM N180, most preferred Ymer TM N120.

[0059] The composition of the waterborne polyurethane resin as the second component B is not particularly limited except for the anionic hydrophilic group I with ammonium ions as counterions and the nonionic hydrophilic group II. Examples thereof include waterborne polyurethane resins obtained by condensation polymerization of polyisocyanates, oligomeric polyols, chain extenders, salt-forming agents, and cross-linking agents, with water as the dispersion medium and containing no or only a small amount of organic solvents.

[0060] In some embodiments, the polyisocyanate is a compound containing two or more isocyanate groups (-N=C=O, abbreviated as NCO) in the molecule, and the polyisocyanate includes at least one of aromatic polyisocyanates, aromatic aliphatic polyisocyanates, aliphatic polyisocyanates, alicyclic polyisocyanates, cycloaliphatic polyisocyanates and polyisocyanate derivatives.

[0061] Among them, aromatic polyisocyanates include but are not limited to at least one of toluene diisocyanate (TDI), diphenylmethane diisocyanate, naphthalene diisocyanate, p-phenylene diisocyanate, dimethyl diphenyl diisocyanate, polymethylene polyphenyl isocyanate, etc.; aromatic aliphatic polyisocyanates include but are not limited to at least one of xylene diisocyanate, tetramethyl metaxylene diisocyanate, etc.; aliphatic polyisocyanates include but are not limited to 1,6-hexamethylene diisocyanate (HDI), trimethyl-1,6-hexamethylene diisocyanate, etc. At least one of; alicyclic polyisocyanates include but are not limited to at least one of isophorone diisocyanate (IPDI), 1,4-cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, methylcyclohexyl diisocyanate, etc.; cycloaliphatic polyisocyanates include but are not limited to at least one of cyclohexane dimethylene diisocyanate, norbornane diisocyanate, etc.; polyisocyanate derivatives include but are not limited to at least one of TDI dimer, TDI-TMP adduct, IPDI trimer, HDI trimer, HDI biuret, etc.

[0062] As the polyisocyanate, from the viewpoint of storage stability and interfacial adhesion, aliphatic polyisocyanates and alicyclic polyisocyanates are preferred, 1,6-hexamethylene diisocyanate and isophorone diisocyanate are more preferred, and isophorone diisocyanate is most preferred.

[0063] In some embodiments, the oligomer polyol is an oligomer of a polycarboxylic acid and a polyol, and includes but is not limited to at least one of a polyester oligomer polyol, a polyether oligomer polyol, and a polyester polyether oligomer polyol containing both a polyester structure and a polyether structure in the molecule.

[0064] Among them, polyester oligomer polyols include but are not limited to at least one of polyethylene adipate diol, polyethylene phthalate diol, polymer-grafted polyester polyol, polycaprolactone diol and polycarbonate diol; polyether oligomer polyols include but are not limited to at least one of polyethylene glycol, polypropylene glycol, polytetramethylene ether diol and polyoxypropylene-ethylene oxide diol.

[0065] As the above-mentioned oligomer polyol, from the viewpoint of improving the adhesion between the carbon fiber and the matrix resin after sizing, polyester oligomer polyol and polyester polyether oligomer polyol are preferred, polyester polyether oligomer polyol is more preferred, aromatic polyester polyether polyol is further preferred, and aromatic polyester polyether diol obtained by condensation polymerization of aromatic dicarboxylic acid with aliphatic diol and polyether diol is most preferred.

[0066] In some embodiments, the chain extender includes the above-mentioned chain extender containing a carboxyl group, the above-mentioned chain extender containing a nonionic hydrophilic group, and a supplementary chain extender, wherein the supplementary chain extender is a chain extender added when the amount of the above-mentioned chain extender containing a carboxyl group and the above-mentioned chain extender containing a nonionic hydrophilic group is insufficient to complete the chain extension reaction.

[0067] The supplementary chain extender is a compound having two active hydrogen groups in the molecule, for example, a compound containing two active hydroxyl groups or a compound containing two active amino groups. Specifically, the compound containing two active hydroxyl groups includes but is not limited to at least one of 1,4-butanediol, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, diethylene glycol, hexanediol, neopentyl glycol, 1,4-cyclohexanediol, bisphenol A and its alkylene oxide adducts, etc. The compound containing two active amino groups includes but is not limited to at least one of ethylenediamine, hydrazine, hexamethylenediamine, isophoronediamine, 3,3'-dichloro-4,4'-diphenylmethanediamine, etc.

[0068] In some embodiments, the crosslinking agent is a compound containing 3 or more active hydrogens, such as at least one of a polyol containing 3 or more active hydrogens, a polyolamine containing 3 or more active hydrogens, and a polyamine containing 3 or more active hydrogens.

[0069] Among them, polyols containing 3 or more active hydrogens include but are not limited to glycerol, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, low molecular weight polyether polyols, etc., polyol amines containing 3 or more active hydrogens include but are not limited to at least one of diethanolamine, triethanolamine, etc., and polyamines containing 3 or more active hydrogens include but are not limited to at least one of diethylenetriamine, triethylenetetramine, etc.

[0070] From the viewpoint of interfacial adhesion and reaction controllability, trimethylolethane, trimethylolpropane, pentaerythritol, and diethylenetriamine are preferred, trimethylolpropane and trimethylolethane are more preferred, and trimethylolpropane is most preferred.

[0071] In some embodiments, the salt-forming agent is a compound that can form a salt with a chain extender containing a carboxyl group, and the salt-forming agent includes but is not limited to at least one of diethylamine, triethylamine, tributylamine, ethanolamine, diethanolamine, triethanolamine, N,N-dimethylethanolamine and ammonia water; preferably triethylamine, diethanolamine, triethanolamine, N,N-dimethylethanolamine, further preferably triethylamine and N,N-dimethylethanolamine, and most preferably triethylamine.

[0072] In some embodiments, the organic solvent includes at least one of a water-soluble solvent and a water-insoluble solvent. The water-soluble solvent includes, but is not limited to, at least one of acetone, 2-butanone, dioxane, N,N-dimethylformamide, and N-methylpyrrolidone; the water-insoluble solvent includes, but is not limited to, at least one of ethyl acetate and toluene.

[0073] Among the above-mentioned organic solvents, acetone or 2-butanone is preferred from the viewpoints of cost and handling properties.

[0074] In some embodiments, the weight percentage of the second component in the non-volatile components is 1% to 80%, preferably 5% to 50%. When the weight percentage is less than 1%, the process operability of the carbon fiber after sizing is difficult to meet the requirements; when the weight percentage is greater than 80%, the adhesion between the carbon fiber and the matrix resin after sizing is significantly reduced.

[0075] The water-based polyurethane resin as the second component B comprises, by weight, 70 to 150 parts of polyisocyanate, 140 to 270 parts of oligomer polyol, 2 to 20 parts of chain extender having the structure of formula (1), 5 to 55 parts of chain extender having the structure of formula (2), 0 to 50 parts of supplementary chain extender, 0 to 40 parts of cross-linking agent, and 1 to 25 parts of salt-forming agent.

[0076] In some embodiments, the present invention provides a sizing agent for carbon fiber, which, in addition to containing a first component A and a second component B, preferably further contains a third component C, which is a vinyl ester resin C A , unsaturated polyester resin CB By containing the third component C, the bonding property between the sized carbon fibers and the free radical polymerization matrix resin can be enhanced.

[0077] In the present invention, vinyl ester resin C A It is a resin oligomer with an aliphatic or aromatic organic compound as the skeleton, and the terminal group or side group is at least one of a vinyl ester group, an acrylate group and a methacrylate group.

[0078] As the vinyl ester resin C A , examples include polyalkoxy glycol di(meth)acrylate, 2-(meth)acryloyloxyethyl phthalate, 2(meth)acryloyloxyethyl 2-hydroxyethyl phthalate, 2(meth)acryloyloxyethyl-2-hydroxypropyl-phthalate, neopentyl glycol (meth)acrylate benzoate, bisphenol A di(meth)acrylate, alkylene oxide-added bisphenol A di(meth)acrylate, bisphenol A diglycidyl ether (meth)acrylate adduct, alkylene oxide-added bisphenol A diglycidyl ether (meth)acrylate adduct, and the like.

[0079] The above vinyl ester resin C A Among them, from the viewpoint of strengthening the adhesion with the free radical polymerization type matrix resin, compounds with an aromatic organic compound as the skeleton and an end group or side group containing two or more non-aromatic unsaturated double bonds are preferred, and bisphenol A di(meth)acrylate, alkylene oxide added bisphenol A di(meth)acrylate, bisphenol A diglycidyl ether (meth)acrylate adduct, and alkylene oxide added bisphenol A diglycidyl ether (meth)acrylate adduct are further preferred.

[0080] In the present invention, the unsaturated polyester resin C B It is obtained by condensation polymerization of unsaturated dibasic acid or acid anhydride, saturated dibasic acid or acid anhydride and diol. It is a resin oligomer containing ester group and non-aromatic unsaturated double bond in the molecule.

[0081] Examples of the unsaturated dibasic acid or acid anhydride include maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, cis-hexadienedioic acid, trans-hexadienedioic acid, cis-methylbutenedioic acid, and trans-methylbutenedioic acid.

[0082] Examples of the saturated dibasic acid or anhydride include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, nadic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, adipic acid, and sebacic acid.

[0083] Examples of the diol include ethylene glycol, 1,2-propylene glycol, diethylene glycol, neopentyl glycol, hydrogenated bisphenol A, and alkylene oxide-added bisphenol A.

[0084] The above unsaturated polyester resin C B Among them, from the viewpoint of strengthening the adhesion to the free radical polymerization type matrix resin, the unsaturated polyester obtained by condensing at least one of maleic acid, maleic anhydride, fumaric acid, and fumaric anhydride with bisphenol A added by alkylene oxide is preferred, the unsaturated polyester obtained by condensing fumaric acid or fumaric anhydride with bisphenol A added by alkylene oxide is further preferred, and the unsaturated polyester obtained by condensing fumaric acid or fumaric anhydride with bisphenol A added by ethylene oxide is most preferred.

[0085] The above unsaturated polyester resin C B The acid value is preferably 37 to 140 mgKOH / g, more preferably 56 to 112 mgKOH / g.

[0086] When the sizing agent for carbon fiber of the present invention contains compound C, the weight percentage of compound C in the non-volatile components is preferably 5% to 50%.

[0087] In some embodiments, the components further include a surfactant as a fourth component D. The surfactant D is used to disperse the first component A, the third component C, and other ingredients in water. Nonionic surfactants and anionic surfactants are preferred. Surfactants D may be used alone or in combination of two or more.

[0088] Specific examples of the above-mentioned nonionic surfactants include higher fatty alcohol polyoxyethylene ethers such as lauryl alcohol polyoxyethylene ether, oleyl alcohol polyoxyethylene ether, lauryl alcohol polyoxyethylene polyoxypropylene ether, cetearyl alcohol polyoxyethylene ether, 2-ethyl-1-hexyl polyoxyethylene ether, etc., alkylphenol polyoxyethylene ethers such as nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, etc., polycyclic phenol polyoxyethylene ethers such as styrylphenol polyoxyethylene ether, distyrylphenol polyoxyethylene ether, tristyrylphenol polyoxyethylene ether, cumylphenol polyoxyethylene ether, etc., alkylamine polyoxyethylene ethers such as laurylamine polyoxyethylene ether, octadecylamine polyoxyethylene ether, etc., castor oil polyoxyethylene ether, hydrogenated castor oil polyoxyethylene ether, fatty acid polyoxyethylene esters such as polyethylene glycol monostearate, polyethylene glycol distearate, polyethylene glycol monolaurate, polyethylene glycol monooleate, polyethylene glycol monomyristate, etc., anhydrous sorbitan, Fatty acid esters (Span series) such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trimonooleate, etc., polyoxyethylene sorbitan fatty acid esters (Tweer series) such as polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, etc., polyoxyethylene hydrogenated castor oil fatty acid esters such as polyoxyethylene hydrogenated castor oil tricaprylate, polyoxyethylene hydrogenated castor oil stearate, etc., glycerol fatty acid esters such as glycerol monostearate, glycerol monolaurate, glycerol monopalmitate, glycerol trioleate, etc., alkyl amides such as stearic acid diethanolamide, lauric acid diethanolamide, etc., and oxyethylene-oxypropylene block or random copolymers.

[0089] Specific examples of the anionic surfactants include carboxylates such as laurate, oleate, stearate, polyoxyethylene tridecyl ether acetate, pyrrolidone carboxylates, sulfonates such as lauryl sulfonate, myristyl sulfonate, cetyl sulfonate, oleyl sulfonate, stearyl sulfonate, myristyl isethionate, dodecylbenzenesulfonate, hexadecyl diphenyl ether disulfonate, and sulfates such as lauryl sulfate, oleyl sulfate, stearyl sulfate, polyoxyethylene lauryl ether sulfate. Acid salts, polyoxyalkylene lauryl ether sulfate salts, polyoxyethylene oleyl ether sulfate salts, castor oil fatty acid sulfate salts, palm oil fatty acid sulfate salts, sperm oil fatty acid sulfate salts, castor oil sulfate salts, palm oil sulfate salts, sperm oil sulfate salts, etc., phosphate salts such as lauryl phosphate salts, cetyl phosphate salts, octyl phosphate salts, oleyl phosphate salts, stearyl phosphate salts, polyoxyethylene lauryl ether phosphate salts, polyoxyethylene oleyl ether phosphate salts, polyoxyethylene stearyl ether phosphate salts, etc.

[0090] Among the surfactants D, from the viewpoint of improving the storage stability of the sizing agent and the wettability to the matrix resin, at least one of a nonionic surfactant having an aromatic hydrocarbon group and an anionic surfactant is preferred, and a nonionic surfactant having an aromatic hydrocarbon group is more preferred.

[0091] When the sizing agent for carbon fiber of the present invention contains a surfactant D, the weight percentage of the surfactant D in the non-volatile component is preferably 10% to 50%, more preferably 15% to 30%.

[0092] More specifically, when the non-volatile components in the sizing agent for carbon fiber include a first component A and a second component B, the first component A accounts for 20% to 99% and the second component B accounts for 1% to 80% by weight.

[0093] When the non-volatile components in the sizing agent for carbon fiber include a first component A, a second component B and a fourth component D, calculated by weight percentage, the first component A is 30% to 80%, the second component B is 5% to 50%, and the fourth component D is 10% to 50%.

[0094] When the non-volatile components in the sizing agent for carbon fiber include a first component A, a second component B, a third component C and a fourth component D, calculated by weight percentage, the first component A is 25% to 50%, the second component B is 5% to 30%, the third component C is 5% to 50%, and the fourth component D is 15% to 30%.

[0095] The manufacturing method of the carbon fiber sizing agent of the present invention is not particularly limited. The sizing agent can be prepared by mixing the components by conventional methods, shearing, and then dispersing in water. Alternatively, the sizing agent can be prepared by mixing aqueous dispersions of the components.

[0096] The average particle size of the carbon fiber sizing agent of the present invention is not particularly limited. From the perspective of storage stability, it is preferably 1000 nm or less, more preferably 500 nm or less, and even more preferably 300 nm or less. It should be noted that the average particle size of the present invention is measured using a nanoparticle size analyzer and a zeta potential analyzer (Nano ZS90, manufactured by Malvern Panalytical, UK).

[0097] The weight proportion of the non-volatile component of the sizing agent for carbon fiber of the present invention is not particularly limited. From the perspective of transportation economy, storage stability and product handling, it is preferably 10% to 80%, more preferably 20% to 70%, and most preferably 30% to 50%.

[0098] Furthermore, the present invention provides a carbon fiber bundle comprising a raw carbon fiber bundle and the aforementioned carbon fiber sizing agent, wherein the carbon fiber sizing agent is attached to the raw carbon fiber bundle. The carbon fiber sizing agent may be dissolved or dispersed in an organic solvent and then attached to the raw carbon fiber bundle. Alternatively, the carbon fiber sizing agent may be dissolved or dispersed in water and then attached to the raw carbon fiber bundle. For environmental, safety, health, and workability considerations, it is preferred to dissolve or disperse the carbon fiber sizing agent in water and then attach to the raw carbon fiber bundle.

[0099] The raw carbon fiber bundle can be obtained by processing any precursor of rayon, pitch, or polyacrylonitrile. The method for attaching the carbon fiber sizing agent to the raw carbon fiber bundle is not particularly limited, and roll impregnation, spraying, and the like can be employed. Roll impregnation is preferred for uniform sizing. The method for drying the attached carbon fiber bundle is also not particularly limited, and contact-type heated roll drying, non-contact hot air drying, or a combination of the two methods can be employed.

[0100] The carbon fiber bundle of the present invention is preferably a bundle formed by bundling 3,000 to 50,000 (3K to 50K) fiber monofilaments.

[0101] In the present invention, the amount of sizing agent attached to the carbon fiber bundle is 0.1% to 20% of the total weight of the sizing agent and the carbon fiber bundle. For continuous carbon fibers, the amount of sizing agent attached is preferably 0.5% to 10%, more preferably 0.5% to 3%. For chopped carbon fibers (cut to a specified length ranging from 1 to 15 mm), the amount is preferably 0.5% to 20%, more preferably 1% to 10%.

[0102] If the attachment amount of the above-mentioned sizing agent is less than 0.1%, the fiber bundle will not be sufficiently bundled and the process passability will deteriorate. If the attachment amount is more than 20%, the fiber bundle will not be sufficiently open and the resin impregnation will deteriorate. As a result, the performance of the composite material cannot be improved.

[0103] The method for determining the amount of sizing agent adhered in this invention uses the Soxhlet extraction method specified in the Chinese standard GB / T29761-2022. Specifically, 3-5g of carbon fiber bundles are placed in a Soxhlet extractor and refluxed with an organic solvent for 2 hours, with at least 8 reflux cycles. The sizing agent adhered is calculated based on the change in weight of the carbon fiber bundles before and after reflux.

[0104] In addition, the present invention also provides a carbon fiber reinforced composite material, which includes a matrix resin and the above-mentioned carbon fiber bundle.

[0105] Examples of the matrix resin include thermosetting resins such as epoxy resins, unsaturated polyester resins, bismaleimide resins, vinyl ester resins, phenolic resins, and cyanate resins; and thermoplastic resins such as polyolefin resins, polyamide resins, thermoplastic polyester resins, polycarbonate resins, ABS resins, polymethyl methacrylate resins, phenoxy resins, polyphenylene sulfide resins, polyethersulfone resins, polyetherimide resins, polyetheretherketone resins, and polyetherketoneketone resins. From the perspective of increasing interfacial bonding strength, thermosetting resins are preferred, and epoxy resins and vinyl ester resins are more preferred.

[0106] Below in conjunction with embodiment, the characteristic and performance of the present invention are described in further detail, will contribute to understanding of the present invention, but the present invention is not limited to these embodiments.In addition, unless otherwise specified, the "percentage (%)" and "part" involved in the embodiment represent "weight %" and "weight part" respectively.

[0107] 1. Performance Testing Method

[0108] The components of the following carbon fiber sizing agent are mixed, sheared and dispersed with water, or the aqueous dispersions of the following components are mixed and diluted with water to obtain a sizing agent with a non-volatile concentration of 30%. Subsequently, the above-mentioned carbon fiber sizing agent is diluted with water to a sizing agent diluent with a non-volatile concentration of 5.0%, and the raw carbon fiber bundle (HF30G-12K, Jiangsu Hengshen Co., Ltd.) is impregnated and sized through a special test dipping tank, dried at 120-150°C for 5-9 minutes, and a carbon fiber bundle with a sizing amount of about 1.2% is obtained after the yarn is collected. The characteristic values ​​of the sizing agent and the sized carbon fiber are characterized by the following method.

[0109] (1) Average particle size

[0110] The sizing agent was diluted with water to a non-volatile matter concentration of about 0.1%. The particle size distribution of the sizing agent was measured using a nanoparticle size and zeta potential analyzer (Nano ZS90, produced by Malvern Panalytical, UK). Three samples with concentrations differing by one order of magnitude were selected for measurement, and the average Z-average particle size was taken.

[0111] (2) Storage stability

[0112] The sizing agent having a non-volatile matter concentration of 30% was sealed and stored in a forced air drying oven at 40° C. The appearance of the sizing agent was visually observed, and the storage stability of the sizing agent was evaluated based on the following criteria. The results indicated that ◎ and ○ were acceptable.

[0113] ◎: 60 days and above, no delamination;

[0114] ○: 30 days and above, less than 60 days, stratified;

[0115] △: 7 days and above, less than 30 days, divided into different levels;

[0116] ×: Less than 7 days, delamination.

[0117] (3) Sizing agent adhesion

[0118] Use the Soxhlet extraction method specified in Chinese standard GB / T 29761-2022. Place 3-5g of carbon fiber bundles in a Soxhlet extractor and add sufficient 2-butanone for extraction. Set the furnace temperature above 90°C to ensure that the 2-butanone refluxes at least eight times within two hours. The extraction time is two hours. Calculate the amount of sizing agent attached based on the weight change of the carbon fiber bundles before and after extraction.

[0119] (4) Wear resistance

[0120] A carbon fiber bundle was placed in contact with six chrome-plated stainless steel rods at a 120° contact angle under an unwinding tension of 200g. The bundle was then passed at a constant speed over two polyurethane sponges with a 250g normal load. The weight of fuzz per unit length of the carbon fiber bundle adhering to the polyurethane sponges was measured as the amount of fuzzing. The abrasion resistance of the carbon fiber bundle was determined according to the following criteria: ◎ and ○ indicate a passing score.

[0121] ◎: The number of carbon fiber filaments per unit length is less than 3mg;

[0122] ○: The number of carbon fiber strands per unit length is 3-5 mg;

[0123] △: The number of carbon fiber strands per unit length is 6 to 10 mg;

[0124] ×: The number of carbon fiber filaments per unit length is 10 mg or more.

[0125] (5) Overhang value

[0126] Cut a 40cm long carbon fiber bundle, fix one end on an iron frame, attach a 100g vertical load to the other end, and let it stand for 30 minutes at (22±3)℃ and relative humidity (60±5)% to correct the shape of the bundle. Remove the additional load, straighten the carbon fiber bundle and fix it horizontally on the test table in a manner perpendicular to the edge of the table. Measure with a ruler and ensure that the horizontal distance between one end of the bundle and the edge of the table is 25cm. Put down the carbon fiber bundle and let it droop naturally. After 2 minutes, measure the horizontal distance between the end of the bundle and the edge of the table. Take the average of the three measured values, which is the drape value of the carbon fiber bundle.

[0127] (6) Physical property retention

[0128] The carbon fiber bundles were placed in a constant temperature and humidity chamber at 85°C and 45% relative humidity for 10 days of accelerated aging. After removal, the changes in the bundle drape value were measured. The criteria for determining the physical property retention of the carbon fiber bundles are as follows: ◎ and ○ indicate a pass.

[0129] ◎: The drape value of the carbon fiber bundle hardly changes;

[0130] ○: The drape value of the carbon fiber bundle changes by 1 to 2 cm;

[0131] △: The drape value of the carbon fiber bundle varies from 3 to 6 cm.

[0132] ×: The drape value of the carbon fiber bundle changed by 6 cm or more, or the bundle was curled and could not be measured.

[0133] (7) Interface adhesion

[0134] The interface adhesion was evaluated by the droplet debonding method using the composite material interface evaluation device HM410 (Toei Industry Co., Ltd., Japan). Carbon fiber monofilaments were randomly taken out from the carbon fiber bundles of the examples and comparative examples, gently straightened and fixed on a stainless steel template using shadowless glue. The matrix resin was transferred to the carbon fiber monofilament with a pin to form approximately spherical resin droplets with a diameter of about 40 to 100 μm. After heating and curing in an oven, a test specimen was obtained. The specimen was fixed in the interface evaluation device, and the droplet embedding length l and the fiber diameter d were observed and measured using an optical microscope. After the solid resin came into contact with the tool, the force F required to peel the droplet from the fiber was measured and recorded. max .

[0135] The interfacial shear strength τ of the composite material can be calculated by τ = F max / πdl, the greater the interfacial shear strength, the stronger the bonding between the fiber and the resin.

[0136] (8) Method for curing matrix resin liquid

[0137] Epoxy resin and vinyl ester resin were used as the base resin, and the curing method was as follows.

[0138] Epoxy resin: Mix 30 parts of curing agent H256 (Zhangjiagang Yarui Chemical Co., Ltd.) and 100 parts of epoxy resin NPEL-128 (Nanya Plastics Industry Co., Ltd.) to obtain a base resin. The mixture was then heated to 100°C in an oven for 2 hours and then at 150°C for 4 hours to obtain a cured epoxy resin.

[0139] Vinyl ester resin: 1 part curing accelerator P001 (Huachang Polymer Co., Ltd.) and 1 part initiator M-50 (Tianjin Nouryon Chemical Co., Ltd.) were added to 100 parts of vinyl ester resin MFE-2 (Huachang Polymer Co., Ltd.) and mixed evenly to obtain a base resin. The mixture was then heated to 60°C in an oven for 2 hours and then at 150°C for 4 hours to obtain a cured vinyl ester resin.

[0140] 2. The components used in the Examples and Comparative Examples are as follows:

[0141] (1) First component A

[0142] Compound A1: Bisphenol A type bifunctional epoxy resin NPEL-128 (Nan Ya Plastics Industries, Ltd.).

[0143] Compound A2: Bisphenol A type bifunctional epoxy resin NPES-901 (Nan Ya Plastics Industries, Ltd.).

[0144] Compound A3: An adduct of methacrylic acid and bisphenol A-type bifunctional epoxy resin NPEL-128. Its synthesis method comprises continuously charging high-purity nitrogen into a four-necked flask equipped with a reflux condenser, a thermometer, and a mechanical stirrer, adding 374 parts of epoxy resin NPEL-128, 86 parts of methacrylic acid, 160 parts of dioxane, 0.4 parts of hydroquinone, and 4 parts of 2,4,6-tris(dimethylaminomethyl)phenol, stirring, and heating to 100°C in an oil bath for 8 hours. The dioxane solvent is then removed by cooling to obtain the target product, a methacrylic acid-modified epoxy resin.

[0145] (2) Second Group B

[0146] Compound B1: Aromatic polyester polyether type waterborne polyurethane resin. The method for synthesizing the dispersion of compound B1 comprises: weighing 200 parts of polyester polyether type oligomeric diol CP-2053 (Nanjing Kangsude Chemical Co., Ltd., hydroxyl value 53-59 mgKOH / g) and adding them into a four-necked flask equipped with a reflux condenser, a mechanical stirring paddle and a thermometer, heating to 120-125°C and dehydrating under reduced pressure. Cooling to below 50°C, adding 113 parts of 2-butanone and stirring thoroughly, continuing to add 13.4 parts of trimethylolpropane and 111 parts of isophorone diisocyanate, heating to 75-80°C and reacting for 3 hours to obtain a prepolymer solution. Cooling to below 50°C, adding 5.65 parts of the chain extender 2,2-dimethylolpropionic acid represented by formula (1) and 22.6 parts of the chain extender Ymer represented by formula (2) TMN120 (Perstorp) and 19.2 parts of neopentyl glycol were heated to 75-80°C for 3 hours to carry out chain extension reaction. The temperature was lowered to below 40°C, 4.26 parts of triethylamine were added for neutralization reaction, 1242 parts of deionized water were added under high shear, the temperature was raised to 50°C, 2-butanone was removed under reduced pressure and the water content was adjusted to obtain an aromatic polyester polyether type waterborne polyurethane resin dispersion B1 with a non-volatile content of 30% and an average particle size of 86.4 nm; in the above compound B1, the nonionic hydrophilic group (II) is The anionic hydrophilic group (Ⅰ) with ammonium ion as counter ion is The weight ratio of the two (II / I) is 3.3.

[0147] Synthesis of dispersions of compounds B2 to B10 and B'1 to B'6

[0148] The above-mentioned synthetic raw materials and their addition amounts were adjusted and listed in Tables 1 and 2. Using the same synthesis method as compound B1, aqueous polyurethane resin dispersions B2-B10, B'1, B'3-B'5 with a non-volatile content of 30% were obtained. In Synthesis Example B'2, when only nonionic hydrophilic groups II were present but no anionic hydrophilic groups I with ammonium ions as counterions were present, and in Synthesis Example B'6, when polyethylene glycol 600 containing nonionic hydrophilic groups was used in place of the chain extender having the structure of formula (2), no dispersion of compound B was obtained.

[0149] It should be noted that CP-2059 and CP-2280 in Tables 1 and 2 are both products of Nanjing Kangsude Chemical Co., Ltd. CP-2059 is an aromatic polyester polyether oligomer polyol with a hydroxyl value of 53-59 mgKOH / g, and CP-5602 is an aliphatic polyester polyether oligomer polyol with a hydroxyl value of 53-59 mgKOH / g. Furthermore, the amount of solvent added can be adjusted based on the viscosity of the reactants, and the amount of water added can be adjusted based on a solids content of 30%. The total weight of the raw materials should be between 370 and 380 parts.

[0150] Table 1. Raw materials and addition amounts used in B1 to B8

[0151]

[0152] Table 2. Raw materials and addition amounts used for B9-B10 and B'1-B'6

[0153]

[0154]

[0155] (3) The third component C

[0156] Compound CA 1: Bisphenol A ethoxylate (3 mol) diacrylate.

[0157] Compound C A 2: Bisphenol A glycerol diacrylate.

[0158] Compound C A 3: Bisphenol A ethoxylate (30 mol) dimethacrylate.

[0159] Compound C B 1: A compound obtained by condensing fumaric acid and bisphenol A ethoxylate (2 moles) in a molar ratio of 4:3. The synthesis method comprises the following steps: weighing 475 parts of bisphenol A ethoxylate BPE-02 (Nantong Chenrun Chemical Co., Ltd.) and 332 parts of fumaric acid, adding the mixture to a four-necked flask equipped with a reflux condenser, a mechanical stirring paddle, and a thermometer, introducing high-purity nitrogen, and heating the mixture to 160°C for an esterification reaction for about 6 hours. Subsequently, the nitrogen flow rate was increased, the temperature was raised to 200°C for the reaction, and the water generated by the condensation reaction was removed under reduced pressure for 2 hours to obtain compound C having an acid value of 74 mg KOH / g. B 1.

[0160] Compound C B 2: A compound obtained by condensing fumaric acid and bisphenol A ethoxylate (2 moles) in a molar ratio of 5:4. The synthesis method comprises the following steps: weighing 506 parts of bisphenol A ethoxylate BPE-02 (Nantong Chenrun Chemical Co., Ltd.) and 332 parts of fumaric acid, adding the mixture to a four-necked flask equipped with a reflux condenser, a mechanical stirring paddle, and a thermometer, introducing high-purity nitrogen, and heating the mixture to 160°C for an esterification reaction for about 6 hours. Subsequently, the nitrogen flow rate was increased, the temperature was raised to 200°C for the reaction, and the water generated by the condensation reaction was removed under reduced pressure for 2 hours to obtain compound C having an acid value of 57 mg KOH / g. B 2.

[0161] (4) Group 4 D

[0162] Compound D1: tristyrylphenol polyoxyethylene polyoxypropylene ether (Haian Petrochemical Plant, Jiangsu Province).

[0163] Compound D2: tristyrylphenol polyoxyethylene ether (Haian Petrochemical Plant, Jiangsu Province).

[0164] Compound D3: distyrylphenol polyoxyethylene ether (Haian Petrochemical Plant, Jiangsu Province).

[0165] Compound D4: polyethylene glycol octylphenyl ether X-100 (Haian Petrochemical Plant, Jiangsu Province).

[0166] Compound D5: castor oil polyoxyethylene ether EL-90 (Haian Petrochemical Plant, Jiangsu Province).

[0167] The raw materials of Examples 1-10 and Comparative Examples 1-6 are selected as shown in Tables 3 and 4. No third component C is added in Examples 1-10 and Comparative Examples 1-6.

[0168] Table 3. Ingredients and dosages of Examples 1-8

[0169]

[0170]

[0171] Table 4. Ingredients and dosages of Examples 9-10 and Comparative Examples 1-6

[0172]

[0173]

[0174] As shown in Tables 3 and 4, compared to Comparative Examples 1 to 6, Examples 1 to 10 achieved storage-stable carbon fiber sizing agents by controlling the mass ratio (II / I) of the nonionic hydrophilic group II to the anionic hydrophilic group I with ammonium ions as counterions in Compound B within a range of 0.5 to 20. Furthermore, the sizing yielded excellent physical property retention in the carbon fiber bundles. Furthermore, the interfacial adhesion between the carbon fiber and the epoxy resin and vinyl ester resin was improved by 44% and 19%, respectively.

[0175] Comparative Example 1 does not use compound B. Although its storage stability is qualified, its wear resistance is unqualified and its interface adhesion is low. Compound B'1 is used in Comparative Example 2, but the mass ratio of the two hydrophilic groups (II / I) is more than 25, which is not within the scope of the present invention. The proportion of the anionic hydrophilic group I is too small, resulting in its storage stability being unqualified. The proportion of the nonionic hydrophilic group II is too large, resulting in a decrease in the physical properties of its film-forming material, making the wear resistance of the carbon fiber after sizing unqualified, the drape value is low, and the interface adhesion is significantly low. Comparative Examples 3 and 4 use compounds B'3 and B'4, respectively. The mass ratios of the two hydrophilic groups (II / I) are 0.2 and 0, respectively. The proportion of the nonionic hydrophilic group II is too small or does not contain it, and it is impossible to effectively suppress the reactivity of the ammonium ions in the anionic hydrophilic group I to the epoxy groups in the compound A, resulting in its storage stability, wear resistance and physical property retention being unqualified, the drape value is significantly higher, and the interface adhesion is significantly low. Compound B'5 used in Comparative Examples 5 and 6 uses a chain extender with a structure other than formula (2). Although the mass ratio of the two hydrophilic groups (II / I) is 3.5, which is within the scope of the present invention, its storage stability, wear resistance and physical property retention are all unqualified, and its drape value and interfacial adhesion are significantly low.

[0176] Table 5. Ingredients and amounts of Examples 11-18

[0177]

[0178] As shown in Table 5, the carbon fiber sizing agents in Examples 11 to 18 exhibited good storage stability and excellent retention of the physical properties of the carbon fiber bundles. Furthermore, the inclusion of Compound C in Examples 11 to 18 improved the interfacial adhesion between the carbon fibers and the vinyl ester resin by more than 30% compared to Examples 1 to 10.

[0179] In summary, the carbon fiber sizing agent provided by the present invention can reduce the reactivity of the ammonium ions from the anionic hydrophilic group I to the epoxy groups in the first component A by introducing the nonionic hydrophilic group II into the macromolecule of the second component B, thereby significantly improving the storage stability of the compound sizing agent and suppressing the change in the physical properties of the sizing carbon fiber products with increasing storage time, thereby improving the storage time, having good process operation performance, and high wettability to the matrix resin. By using the carbon fiber bundles treated with the sizing of the present invention, a composite material with excellent mechanical properties can be obtained.

[0180] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A sizing agent for carbon fiber, characterized in that: The invention comprises a first component and a second component, wherein the first component is a compound having at least one epoxy group in the molecule, and the second component is a waterborne polyurethane resin having both anionic hydrophilic group I with ammonium ion as counter ion and nonionic hydrophilic group II in the molecule; The anionic hydrophilic group I with ammonium ion as counter ion is obtained by reacting a chain extender containing a carboxyl group with a macromolecular skeleton composed of polyurethane segments, and then neutralizing with amine or ammonia to form ammonium carboxylate; the structure of the chain extender containing a carboxyl group is R1 is a hydrogen atom or a C1-C3 hydrocarbon group; The nonionic hydrophilic group II is obtained by reacting a chain extender containing a nonionic hydrophilic group with a macromolecular skeleton composed of polyurethane segments; the structural formula of the chain extender containing a nonionic hydrophilic group is R2 is a hydrogen atom or a C1-C3 hydrocarbon group; R3 is a C1-C3 hydrocarbon group; AO is a C2-C4 alkyleneoxy group, m is the number average molar addition number of the alkyleneoxy group, m=4-60; The weight ratio (II / I) of the nonionic hydrophilic group II to the anionic hydrophilic group I with ammonium ion as counter ion is 0.5-20.

2. The sizing agent for carbon fiber according to claim 1, characterized in that The weight ratio (II / I) of the nonionic hydrophilic group II to the anionic hydrophilic group I with ammonium ion as counter ion is 1 to 10, preferably 2 to 6; And / or, R1 is any one of methyl and ethyl; R2 is methyl; R3 is methyl; AO is at least one of ethyleneoxy, propyleneoxy and butyleneoxy, and m=10-35.

3. The sizing agent for carbon fiber according to claim 1, characterized in that The carboxyl-containing chain extender includes at least one of 2,2-dimethylol propionic acid, 2,2-dimethylol butyric acid and 2,2-dimethylol valeric acid; And / or, the chain extender containing nonionic hydrophilic groups includes Ymer TM N180, Ymer TM N120 and Ymer TM At least one of the N90.

4. The sizing agent for carbon fiber according to claim 1, characterized in that The weight percentage of the first component in the non-volatile components is 20% to 99%, the weight percentage of the second component in the non-volatile components is 1% to 80%, and the weight percentage of the total weight of the anionic hydrophilic group I with ammonium ions as counterions and the non-ionic hydrophilic group II in the second component is 1% to 20%, preferably 3% to 10%.

5. The sizing agent for carbon fiber according to claim 1, characterized in that The first component is at least one of an epoxy resin and a modified epoxy resin; Preferably, the epoxy resin includes glycidyl ether epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, heterocyclic epoxy resin and mixed epoxy resin, preferably glycidyl ether epoxy resin, more preferably bisphenol A epoxy resin and bisphenol F epoxy resin; Preferably, the modified epoxy resin includes at least one of a chemically modified epoxy resin and a physically modified epoxy resin; wherein the chemically modified epoxy resin includes (meth)acrylic acid modified, polyurethane modified, and polyethersulfone modified epoxy resins; and the physically modified epoxy resin includes resin blend modified and filler filled modified epoxy resins.

6. The sizing agent for carbon fiber according to claim 1, characterized in that The second component is a waterborne polyurethane resin obtained by condensation polymerization of polyisocyanate, oligomer polyol, chain extender, salt-forming agent and cross-linking agent, with water as the dispersion medium; Preferably, the polyisocyanate comprises at least one of aromatic polyisocyanate, aromatic aliphatic polyisocyanate, aliphatic polyisocyanate, alicyclic polyisocyanate, cycloaliphatic polyisocyanate and polyisocyanate derivatives; Preferably, the oligomer polyol includes at least one of a polyester oligomer polyol, a polyether oligomer polyol, and a polyester polyether oligomer polyol containing both a polyester structure and a polyether structure in the molecule; Preferably, the chain extender includes the chain extender containing a carboxyl group, the chain extender containing a nonionic hydrophilic group and a supplementary chain extender, and the supplementary chain extender includes at least one of 1,4-butanediol, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, diethylene glycol, hexylene glycol, neopentyl glycol, 1,4-cyclohexanediol, bisphenol A and its alkylene oxide adduct, ethylenediamine, hydrazine, hexamethylenediamine, isophoronediamine and 3,3'-dichloro-4,4'-diphenylmethanediamine; Preferably, the cross-linking agent comprises at least one of trimethylolethane, trimethylolpropane, pentaerythritol and diethylenetriamine; Preferably, the salt-forming agent includes at least one of triethylamine, diethanolamine, triethanolamine and N,N-dimethylethanolamine.

7. The sizing agent for carbon fiber according to claim 1, characterized in that The carbon fiber sizing agent further includes a surfactant as a fourth component, wherein the surfactant includes at least one of a nonionic surfactant and an anionic surfactant; Preferably, based on the weight percentage of non-volatile components, the first component is 30% to 80%, the second component is 5% to 50%, and the fourth component is 10% to 50%.

8. The sizing agent for carbon fiber according to claim 7, characterized in that The carbon fiber sizing agent further includes a third component, the third component including at least one of a vinyl ester resin and an unsaturated polyester resin, and in terms of the weight percentage of non-volatile components, the first component is 25% to 50%, the second component is 5% to 30%, the third component is 5% to 50%, and the fourth component is 15% to 30%; The vinyl ester resin is a resin oligomer with an aliphatic or aromatic organic compound as a skeleton and an end group or a side group being at least one of a vinyl ester group, an acrylate group and a methacrylate group; The unsaturated polyester resin is obtained by condensation polymerization of unsaturated dibasic acid or acid anhydride, saturated dibasic acid or acid anhydride and diol, and is a resin oligomer containing both ester groups and non-aromatic unsaturated double bonds in the molecule; Preferably, the vinyl ester resin comprises at least one of polyalkoxy glycol di(meth)acrylate, 2-(meth)acryloyloxyethyl phthalate, 2(meth)acryloyloxyethyl 2-hydroxyethyl phthalate, 2(meth)acryloyloxyethyl-2-hydroxypropyl-phthalate, neopentyl glycol (meth)acrylate benzoate, bisphenol A di(meth)acrylate, alkylene oxide-added bisphenol A di(meth)acrylate, bisphenol A diglycidyl ether (meth)acrylate adduct, and alkylene oxide-added bisphenol A diglycidyl ether (meth)acrylate adduct; Preferably, the unsaturated dibasic acid or anhydride comprises at least one of maleic acid, maleic anhydride, fumaric acid, fumaric anhydride, cis-hexadienedioic acid, trans-hexadienedioic acid, cis-methylbutenedioic acid and trans-methylbutenedioic acid; Preferably, the saturated dibasic acid or anhydride comprises at least one of phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, nadic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, adipic acid and sebacic acid; Preferably, the diol comprises at least one of ethylene glycol, 1,2-propylene glycol, diethylene glycol, neopentyl glycol, hydrogenated bisphenol A and alkylene oxide-added bisphenol A; Preferably, the acid value of the unsaturated polyester resin is 37 to 140 mg KOH / g.

9. A carbon fiber bundle, characterized in that: It comprises a raw carbon fiber bundle and a carbon fiber sizing agent according to any one of claims 1 to 8, wherein the carbon fiber sizing agent is attached to the raw carbon fiber bundle; Preferably, the carbon fiber bundle is a carbon fiber bundle formed by bundling 3K to 50K fiber monofilaments; Preferably, the attached amount of the carbon fiber sizing agent is 0.1% to 20% of the total weight of the carbon fiber sizing agent and the raw carbon fiber bundle.

10. A carbon fiber reinforced composite material, characterized in that: It comprises a matrix resin and the carbon fiber bundle according to claim 9.

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