A carbon fiber sizing agent and its preparation method and application

Abstract

The present invention belongs to the technical field of polymer materials, and provides a carbon fiber sizing agent and a preparation method and application thereof, wherein the preparation method comprises: reacting epoxy acrylate monomer with hydrogenated silicone oil to obtain epoxy silicone oil; reacting the epoxy silicone oil with monocarboxylic acid to obtain hydroxyl-containing silicone oil; reacting the hydroxyl-containing silicone oil, diisocyanate, hydrophilic chain extender, amine chain extender and neutralizer to obtain water-based silicone resin; mixing the water-based silicone resin with a blocked isocyanate crosslinker to obtain a carbon fiber sizing agent. The present invention enables the carbon fiber sizing agent to have excellent high temperature resistance through the design and mutual compounding of materials and processes, and can further enhance the crosslinking effect during high temperature processing, improve the wear resistance and high temperature resistance of carbon fiber materials, and can match the high processing temperature of materials such as PPS, so as to ensure that the carbon fiber material and polymer composite material have high mechanical strength.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and particularly relates to a carbon fiber sizing agent and a preparation method and application thereof. Background Art

[0002] Carbon fiber has the characteristics of light weight, good chemical stability, low thermal expansion coefficient, high strength, high elastic modulus, etc. The composite materials composed of carbon fiber and various matrix resins are widely used in many fields such as aircraft components, automobile components, ship components, civil engineering materials, etc., and can replace traditional metal materials as main load-bearing and secondary load-bearing structural components. However, carbon fiber is prone to fluffing and breaking during the production and processing process, which affects the mechanical properties of carbon fiber products. At the same time, the interface bonding force between carbon fiber and matrix resin is obviously insufficient. In order to solve the above problems, one of the most commonly used methods is to sizing the surface of carbon fiber so that the surface of carbon fiber is coated with a layer of high molecular polymer, which reduces the fluffing and breaking of carbon fiber, avoids mechanical damage, improves the wear resistance and bundling of carbon fiber filaments, and improves the interface bonding force between carbon fiber and matrix resin, thereby improving the overall performance of composite materials.

[0003] Carbon fiber needs to be combined with different types of resins to prepare composite materials, so different resin matrices need to select corresponding sizing agents. For example, CN118388723A discloses a method for preparing a sizing agent for carbon fiber, and the steps are as follows: dissolving epoxy resin in an organic solvent, then adding a modifier thereto and performing a heating reaction to obtain a modified intermediate; after adding an acid to the modified intermediate for reaction, removing the organic solvent in the reaction system to obtain a water-based epoxy resin; adding acrylate, initiator, emulsifier, smoothing agent and water to the water-based epoxy resin and reacting to obtain a sizing agent; the modifier includes at least one of diethanolamine, N,N'-dimethyl-1,3-propylenediamine, methylamine and diisopropylamine, and the acid includes at least one of acetic acid, citric acid, tartaric acid, maleic acid, acidic amino acids and malic acid; the coating formed by the sizing agent can make the corresponding carbon fiber reinforced composite material have good moisture and heat resistance. CN118792885A discloses an emulsion sizing agent, including a main sizing agent and water, wherein the main sizing agent includes, by weight, 80-120 parts of phenolic epoxy resin, 100-150 parts of epoxy vinyl resin, and 10-20 parts of surfactant; the heat resistance and wear resistance of carbon fiber treated with the sizing agent can be improved by combining the phenolic epoxy resin and the epoxy vinyl resin. CN115450050A discloses a polyurethane emulsion sizing agent for carbon fiber, including the following raw materials by weight: 6-10 parts of polyurethane emulsion, 0.2-0.5 parts of silane coupling agent, and 89.5-93.8 parts of deionized water; the polyurethane emulsion is prepared from raw materials such as polyether diol, diisocyanate, hydrophilic chain extender, melamine, mercaptoethanol, and neutralizer; the polyurethane emulsion sizing agent solves the problem of poor wettability of the sizing agent with the main resin in the composite material in the prior art, and has good emulsion stability.

[0004] At present, the main components of sizing agents include epoxy resin, polyurethane, etc. Carbon fibers treated with sizing agents can be used to reinforce plastic products such as epoxy resin, polyamide (PA), polybutylene terephthalate (PBT), etc. However, the application of such products in high processing temperature resins is greatly limited. For example, the processing temperature of polyphenylene sulfide (PPS) materials is as high as 360-400℃, and the existing sizing agents will decompose in large quantities below 300℃, and will be almost consumed at 350℃. At this time, the carbon fiber material will lose the thermoplastic processing effect, and the prepared PPS modified plastic cannot improve the mechanical strength of the PPS material. Therefore, the development of a carbon fiber sizing agent with high temperature resistance is an urgent problem to be solved in this field. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a carbon fiber sizing agent and a preparation method and application thereof. Through the design and mutual compounding of materials and processes, the carbon fiber sizing agent can effectively improve the interfacial bonding strength between the carbon fiber and the matrix resin while having excellent high temperature resistance, and can further enhance the crosslinking effect during high temperature processing, improve the wear resistance of the carbon fiber material, and ensure that the carbon fiber material and the polymer composite material have high mechanical strength.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a carbon fiber sizing agent, the preparation method comprising the following steps:

[0008] (1) subjecting epoxy acrylate monomer to a hydrosilylation reaction with hydrogen-containing silicone oil to obtain epoxy silicone oil;

[0009] (2) reacting the epoxy silicone oil with a monocarboxylic acid to obtain a hydroxyl-containing silicone oil;

[0010] (3) reacting the hydroxyl-containing silicone oil, diisocyanate, hydrophilic chain extender, amine chain extender and neutralizer to obtain a water-based silicone resin;

[0011] (4) The water-based silicone resin is mixed with a blocked isocyanate cross-linking agent to obtain the carbon fiber sizing agent.

[0012] In the preparation method of the carbon fiber sizing agent provided by the present invention, a hydroxyl-containing silicone oil is prepared by a specific method and used as a polyol part, so that the silicon segment is the main segment / soft segment in the formed polyurethane water-based silicone resin, and an amine chain extender is used to improve the temperature resistance of the water-based silicone resin and the carbon fiber sizing agent. Further, the present invention also introduces a blocked isocyanate cross-linking agent, which has thermal deblocking properties, so that the carbon fiber sizing agent has excellent high temperature resistance, and can also be in the high temperature processing process. The cross-linking agent of the thermal deblocking type inside the system can further undergo a cross-linking reaction, improve the cross-linking effect, thereby improving the temperature resistance of the product, and ensuring the characteristics of improving the mechanical strength of carbon fiber materials and polymer composite materials during the processing of PPS materials.

[0013] In summary, the present invention, through the design and mutual compounding of materials and processes, enables the carbon fiber sizing agent to effectively improve the interfacial bonding strength between the carbon fiber and the matrix resin while having significantly improved high temperature resistance, and can further improve the cross-linking effect during high temperature processing, improve the wear resistance and high temperature resistance of the carbon fiber material, and obtain excellent processing temperature resistance, so that it can match and adapt to the high processing temperature (>350°C) of materials such as PPS, ensuring that the carbon fiber material and the polymer composite material have high mechanical strength.

[0014] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the objectives and beneficial effects of the present invention can be better achieved and realized.

[0015] In the present invention, the hydroxyl-containing silicone oil as a polyol is prepared by the following method: first, epoxy acrylate monomer and hydrogen-containing silicone oil are subjected to a silylation reaction to obtain epoxy silicone oil, and then the epoxy group in the epoxy silicone oil reacts with the carboxyl group in the monocarboxylic acid to obtain the hydroxyl-containing silicone oil. The hydroxyl-containing silicone oil has a suitable steric effect, and it reacts with diisocyanate to regulate the reaction rate, which is beneficial to control the molecular weight of the polymer product to form a water-based silicone resin with uniform molecular weight distribution, and then when the carbon fiber sizing agent is used for sizing treatment of carbon fiber, the obtained carbon fiber material has higher wear resistance.

[0016] Preferably, the epoxy acrylate monomer includes glycidyl methacrylate and / or glycidyl acrylate, and glycidyl methacrylate is more preferred.

[0017] Preferably, the hydrogen-containing silicone oil is a silicone oil having a terminal Si-H group.

[0018] Preferably, the epoxy acrylate monomer is glycidyl methacrylate and / or glycidyl acrylate, and the reaction formula of the epoxy acrylate monomer and the silicone oil containing Si-H groups at the terminal is as follows:

[0019]

[0020] Wherein, R1 and R2 are independently selected from C1-C6 (e.g., C2, C3, C4, C5) straight or branched alkyl groups, preferably methyl groups; the wavy line represents the long chain structure of the silicone oil (the long chain structure does not participate in the reaction). R3 is hydrogen or methyl, that is, when R3 is hydrogen, the epoxy acrylate monomer is glycidyl acrylate; when R3 is methyl, the epoxy acrylate monomer is glycidyl methacrylate. Through the above reaction, epoxy silicone oil with an epoxy end group is obtained.

[0021] Preferably, the number average molecular weight (Mn) of the hydrogen-containing silicone oil is 800-2000, for example, it may be 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800 or 1900, as well as specific values ​​between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range.

[0022] Preferably, the molar ratio of the epoxy acrylate monomer to the Si—H group in the hydrogenated silicone oil is (1-1.2):1, for example, 1.02:1, 1.05:1, 1.08:1, 1.1:1, 1.12:1, 1.15:1, 1.18:1, etc.

[0023] Preferably, the hydrosilylation reaction is carried out in the presence of a platinum catalyst.

[0024] Preferably, the platinum catalyst comprises any one of a Custer catalyst, chloroplatinic acid or a supported platinum catalyst.

[0025] Preferably, based on the total mass of the epoxy acrylate monomer and the hydrogen-containing silicone oil as 100%, the amount of the platinum catalyst used is such that the mass of platinum is 50-200 ppm, for example, it can be 60 ppm, 80 ppm, 100 ppm, 120 ppm, 140 ppm, 150 ppm, 160 ppm or 180 ppm, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0026] Preferably, the temperature of the hydrosilylation reaction is 20-120°C, for example, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C or 110°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0027] Preferably, the time of the hydrosilylation reaction is 3-10 h, for example, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h, 8.5 h, 9 h, 9.5 h or 9.8 h, as well as specific values ​​between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific points included in the range.

[0028] Preferably, the monocarboxylic acid includes C2-C10 monocarboxylic acid, for example, it may be C2, C3, C4, C5, C6, C7, C8, C9, or C10 monocarboxylic acid.

[0029] Preferably, the monocarboxylic acid includes any one of propionic acid, n-butyric acid, isobutyric acid, or a combination of at least two of them.

[0030] Preferably, the molar ratio of the monocarboxylic acid to the Si—H group in the hydrogen-containing silicone oil is (1-1.2):1, for example, it can be 1.02:1, 1.05:1, 1.08:1, 1.1:1, 1.12:1, 1.15:1, 1.18:1, etc.

[0031] Preferably, the molar ratio of the monocarboxylic acid to the epoxy group in the epoxy silicone oil is (1-1.2):1, for example, it can be 1.02:1, 1.05:1, 1.08:1, 1.1:1, 1.12:1, 1.15:1, 1.18:1, etc.

[0032] Exemplarily, the reaction formula of the monocarboxylic acid and epoxy silicone oil is as follows:

[0033]

[0034] Wherein, R1 and R2 are independently selected from C1-C6 (e.g., C2, C3, C4, C5) straight or branched alkyl groups, preferably methyl groups; the wavy line represents the long chain structure of the silicone oil (the long chain structure does not participate in the reaction). R3 is hydrogen or methyl; R4 is a residue from a monobasic acid (which does not participate in the reaction). Through the above reaction, a hydroxyl-containing silicone oil containing hydroxyl groups at the end groups is obtained.

[0035] Preferably, the reaction in step (2) is carried out in the presence of a catalyst, and the catalyst includes any one of triphenylphosphine, N,N-dimethylbenzylamine, tetraethylammonium bromide, and tetrabutylammonium bromide, or a combination of at least two thereof.

[0036] Preferably, based on the total mass of the monocarboxylic acid and the hydrogen-containing silicone oil as 100%, the mass of the catalyst in the reaction in step (2) is 0.1-5%, for example, it can be 0.1%, 0.2%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.8%, 4%, 4.2%, 4.5% or 4.8%, as well as specific values ​​between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range.

[0037] Preferably, the reaction temperature in step (2) is 80-130°C, for example, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C or 125°C, as well as specific values ​​between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range.

[0038] Preferably, the reaction time of step (2) is 1-12 h, for example, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h, 8.5 h, 9 h, 9.5 h, 10 h, 10.5 h, 11 h, 11.5 h or 11.8 h, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention no longer exhaustively enumerates the specific points included in the range.

[0039] Preferably, the hydroxyl value of the hydroxyl-containing silicone oil is 40-120 mg KOH / g, for example, it can be 45 mg KOH / g, 50 mg KOH / g, 60 mg KOH / g, 65 mg KOH / g, 70 mg KOH / g, 75 mg KOH / g, 80 mg KOH / g, 90 mgKOH / g, 100 mg KOH / g, 110 mg KOH / g or 115 mg KOH / g, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0040] Preferably, the diisocyanate includes any one of aliphatic diisocyanate, alicyclic diisocyanate, and aromatic diisocyanate, or a combination of at least two of them.

[0041] Preferably, the diisocyanate includes any one of dicyclohexylmethane diisocyanate (HMDI), tetramethyl metaxylylene diisocyanate (TMXDI), toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), and hexamethylene diisocyanate (HDI), or a combination of at least two thereof.

[0042] Preferably, the hydrophilic chain extender includes any one of dimethylol propionic acid, dimethylol butyric acid, and dimethylol acetic acid, or a combination of at least two thereof.

[0043] Preferably, the amine chain extender includes any one of ethylenediamine, hexamethylenediamine, and isophoronediamine, or a combination of at least two of them.

[0044] Preferably, the neutralizing agent includes any one of triethylamine, triethanolamine, 2-amino-2-methyl-1-propanol, and N,N-dimethylethanolamine, or a combination of at least two thereof.

[0045] Preferably, the reaction method in step (3) comprises the following steps:

[0046] The hydroxyl-containing silicone oil is reacted with diisocyanate to obtain a first prepolymer;

[0047] The first prepolymer and the hydrophilic chain extender undergo a two-stage reaction to obtain a second prepolymer;

[0048] The second prepolymer is subjected to a neutralization reaction with a neutralizing agent, and then subjected to a chain extension reaction with an amine chain extender, and water is added for emulsification to obtain the waterborne silicone resin.

[0049] Preferably, the molar ratio of the hydroxyl group in the hydroxyl-containing silicone oil to the NCO group in the diisocyanate is 1:(1.1-1.2), for example, it can be 1:1.11, 1:1.12, 1:1.13, 1:1.14, 1:1.15, 1:1.16, 1:1.17, 1:1.18, 1:1.19, etc.

[0050] Preferably, the molar ratio of the NCO group in the diisocyanate, the hydroxyl group in the hydrophilic chain extender, and the amino group in the amine chain extender is 1:(0.01-0.07):(0.04-0.12).

[0051] Preferably, the molar ratio of the NCO group in the diisocyanate to the hydroxyl group in the hydrophilic chain extender is 1:(0.01-0.07), for example, it can be 1:0.02, 1:0.025, 1:0.03, 1:0.035, 1:0.04, 1:0.045, 1:0.05, 1:0.055, 1:0.06 or 1:0.065, etc., and more preferably 1:(0.02-0.06).

[0052] Preferably, the molar ratio of the NCO group in the diisocyanate to the amino group in the amine chain extender is 1:(0.04-0.12), for example, it can be 1:0.045, 1:0.05, 1:0.06, 1:0.07, 1:0.075, 1:0.08, 1:0.085, 1:0.09, 1:0.095, 1:0.1, 1:0.105, 1:0.11 or 1:0.115, etc., and more preferably 1:(0.05-0.1).

[0053] Preferably, the amount of the neutralizer is such that the acid value of the product of the neutralization reaction is ≤1 mg KOH / g. For example, the acid value of the product of the neutralization reaction may be 0.1 mg KOH / g, 0.2 mg KOH / g, 0.3 mg KOH / g, 0.4 mg KOH / g, 0.5 mg KOH / g, 0.6 mg KOH / g, 0.7 mg KOH / g, 0.8 mg KOH / g, 0.9 mg KOH / g or 0.95 mg KOH / g, as well as specific values ​​between the above-mentioned points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range.

[0054] Preferably, the first stage reaction is carried out in the presence of a catalyst, and the catalyst includes any one of an organic bismuth catalyst, an organic tin catalyst, and an amine catalyst, or a combination of at least two of them.

[0055] Preferably, based on the total mass of the hydroxyl-containing silicone oil and the diisocyanate as 100%, the mass of the catalyst is 0.01-0.5%, for example, it can be 0.02%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.18%, 0.2%, 0.22%, 0.25%, 0.28%, 0.3%, 0.35%, 0.4% or 0.45%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0056] Preferably, the temperature of the first stage reaction is 70-130°C, for example, it can be 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C or 125°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0057] Preferably, the reaction time is 1-8 h, for example, 1.2 h, 1.5 h, 1.8 h, 2 h, 2.2 h, 2.5 h, 2.8 h, 3 h, 3.2 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h, 7 h or 7.5 h, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific point values ​​included in the range.

[0058] Preferably, after the first stage of reaction is completed, the step of cooling the temperature and adding an organic solvent is also included.

[0059] Preferably, the cooling temperature is 30-50°C, for example, it can be 32°C, 35°C, 38°C, 40°C, 42°C, 45°C or 48°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0060] Preferably, the organic solvent comprises a ketone solvent, more preferably acetone and / or butanone, more preferably butanone.

[0061] Preferably, the temperature of the second-stage reaction is 60-80°C, for example, it can be 62°C, 65°C, 68°C, 70°C, 72°C, 75°C, 78°C or 80°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0062] Preferably, the time of the second-stage reaction is 1-6 h, for example, it can be 1.2 h, 1.5 h, 1.8 h, 2 h, 2.2 h, 2.5 h, 2.8 h, 3 h, 3.2 h, 3.5 h, 3.8 h, 4 h, 4.2 h, 4.5 h, 4.8 h, 5 h or 5.5 h, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific point values ​​included in the range.

[0063] Preferably, the temperature of the neutralization reaction is 30-50°C, for example, it can be 32°C, 35°C, 38°C, 40°C, 42°C, 45°C or 48°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0064] Preferably, the neutralization reaction time is 5-60 min, for example, it can be 8 min, 10 min, 12 min, 15 min, 18 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min or 55 min, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0065] As a preferred technical solution of the present invention, the order of the chain extension reaction and water emulsification can be adjusted according to actual conditions, that is, the product of the neutralization reaction is subjected to a chain extension reaction with an amine chain extender and then emulsified with water to obtain the water-based silicone resin; or, the product of the neutralization reaction is subjected to a chain extension reaction with an amine chain extender and then emulsified with water to obtain the water-based silicone resin.

[0066] Preferably, the temperature of the chain extension reaction is 30-70°C, for example, it can be 32°C, 35°C, 38°C, 40°C, 42°C, 45°C, 48°C, 50°C, 52°C, 55°C, 58°C, 60°C, 62°C, 65°C or 68°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0067] Preferably, the chain extension reaction time is 5-60 min, for example, it can be 8 min, 10 min, 12 min, 15 min, 18 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min or 55 min, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0068] Preferably, the mass percentage of NCO groups in the product of the chain extension reaction is ≤0.2%, for example, it can be 0.01%, 0.02%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15% or 0.18%, as well as specific values ​​between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range.

[0069] Preferably, ethanol is optionally added during the water-adding emulsification.

[0070] Preferably, the mass ratio of ethanol to water is 1:(3-15), for example, it can be 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13 or 1:14, etc.

[0071] Preferably, the emulsification is high-speed shear emulsification.

[0072] Preferably, the emulsification time is 1-6 h, for example, it can be 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h or 5.5 h, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0073] Preferably, the process further comprises a step of removing the organic solvent after the emulsification.

[0074] Preferably, the removing is carried out under vacuum conditions.

[0075] As a preferred technical solution of the present invention, the reaction method in step (3) comprises the following steps:

[0076] The hydroxyl-containing silicone oil and diisocyanate are reacted at 70-130° C. for 1-8 h to obtain a first prepolymer; the temperature is lowered to 30-50° C., a ketone solvent is added, and then a hydrophilic chain extender is added, and the reaction is carried out at 60-80° C. for 1-6 h to obtain a second prepolymer;

[0077] The second prepolymer is reacted with a neutralizing agent at 30-50° C. for a neutralization reaction for 5-60 min, and then with an amine chain extender at 30-70° C. for a chain extension reaction for 5-60 min until the mass percentage of NCO groups in the product is ≤0.2%, water is added for high-speed emulsification for 1-6 h, and the organic solvent is removed in vacuo to obtain the water-based silicone resin.

[0078] In the present invention, the reaction process of step (3) can be understood as the preparation process of waterborne polyurethane. First, the hydroxyl group (-OH) in the hydroxyl-containing silicone oil reacts with the -NCO group in the diisocyanate to obtain a carbamate bond (-NH-CO-O-). Since the -NCO group in the diisocyanate is excessive relative to the hydroxyl group in the hydroxyl-containing silicone oil, the obtained first prepolymer is -NCO-terminated. The -NCO group in the first prepolymer reacts with the -OH in the hydrophilic chain extender to generate a second prepolymer terminated with -NCO group, and the side chain of the second prepolymer carries a hydrophilic group (carboxyl group); the hydrophilic group (carboxyl group) in the second prepolymer reacts with the basic group in the neutralizer to neutralize the acidic group; then the terminal -NCO group of the second prepolymer reacts with the amino group (-NH2) in the amine chain extender to generate a urea bond (-NH-CO-NH-) and block the terminal -NCO group; finally, water is added for emulsification to obtain a waterborne silicone resin. Preferably, the waterborne silicone resin is in the form of an emulsion.

[0079] Preferably, the solid content of the water-based silicone resin is 25-35%, for example, it can be 26%, 27%, 28%, 28.5%, 29%, 29.5%, 30%, 30.5%, 31%, 31.5%, 32%, 32.5%, 33% or 34%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific point values ​​included in the range, and 28-32% is further preferred.

[0080] Preferably, based on the mass of the water-based silicone resin (the mass of the emulsion) as 100%, the mass of the blocked isocyanate cross-linking agent is 5-15%, for example, it can be 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13% or 14%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0081] Preferably, the blocked isocyanate cross-linking agent is prepared by the following method, which comprises:

[0082] The isocyanate trimer is subjected to a first reaction with polyethylene glycol monomethyl ether to obtain an intermediate product; and the intermediate product is subjected to a second reaction with a blocking agent to obtain the blocked isocyanate cross-linking agent.

[0083] As a preferred technical solution of the present invention, a cyclic isocyanate trimer is reacted with polyethylene glycol monomethyl ether and a blocking agent to obtain a blocked isocyanate cross-linking agent having thermal unblocking properties. The isocyanate trimer is compounded with a water-based silicone resin to make the carbon fiber sizing agent have a higher glass transition temperature and significantly improved high temperature resistance. A cross-linking reaction can occur during high temperature processing, further enhancing the cross-linking effect, improving the high temperature resistance of the carbon fiber material, and obtaining an excellent processing temperature resistance effect.

[0084] Preferably, the isocyanate trimer includes isophorone diisocyanate trimer (IPDI trimer) and / or hexamethylene diisocyanate trimer (HDI trimer), more preferably IPDI trimer.

[0085] Preferably, the number average molecular weight of the polyethylene glycol monomethyl ether is 400-800, for example, 450, 500, 550, 600, 650, 700 or 750, as well as specific values ​​between the above values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific values ​​included in the range.

[0086] Preferably, the molar ratio of the NCO group in the isocyanate trimer to the hydroxyl group in the polyethylene glycol monomethyl ether is 1:(0.12-0.18), for example, it can be 1:0.125, 1:0.13, 1:0.135, 1:0.14, 1:0.145, 1:0.15, 1:0.155, 1:0.16, 1:0.165, 1:0.17 or 1:0.175, etc.

[0087] Preferably, the blocking agent includes any one of 3,5-dimethylpyrazole, methyl ethyl ketone oxime, and caprolactam, or a combination of at least two thereof.

[0088] Preferably, the molar ratio of the NCO group in the isocyanate trimer, the hydroxyl group in the polyethylene glycol monomethyl ether, and the blocking agent is 1:(0.12-0.18):(0.82-0.93), wherein "0.12-0.18" can be 0.125, 0.13, 0.135, 0.14, 0.145, 0.15, 0.155, 0.16, 0.165, 0.17 or 0.175, etc., and "0.82-0.93" can be 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.9, 0.91 or 0.92, etc.

[0089] Preferably, the molar ratio of NCO groups in the intermediate product to the blocking agent is 1:(1-1.05), for example, it can be 1:1.005, 1:1.01, 1:1.015, 1:1.02, 1:1.025, 1:1.03, 1:1.035, 1:1.04 or 1:1.045, etc., and 1:(1-1.03) is further preferred.

[0090] In the preparation process of the blocked isocyanate crosslinker, a small amount of NCO groups in the isocyanate trimer are first reacted with the hydroxyl groups in polyethylene glycol monomethyl ether to generate carbamate bonds (-NH-CO-O-), and a flexible chain segment with good water dispersibility is introduced into the intermediate product; the intermediate product contains NCO groups, which react with the functional groups in the blocking agent (such as the ring N atom in 3,5-dimethylpyrazole, the oxime group -C=NOH in methyl ethyl ketone oxime, and the amide group -CO-NH- in caprolactam) to undergo nucleophilic addition reaction to obtain a stable adduct, which is non-reactive at room temperature / low temperature, and the blocking bond is broken under high temperature conditions, that is, the adduct is thermally unblocked, releasing the NCO group, and achieving a crosslinking effect.

[0091] Preferably, the first reaction is carried out in the presence of an organic solvent, and the organic solvent includes an alcohol ether solvent, preferably propylene glycol methyl ether acetate and / or dipropylene glycol methyl ether acetate.

[0092] Preferably, the mass ratio of the isocyanate trimer to the organic solvent is (1-10):1, for example, it can be 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1 or 9:1.

[0093] Preferably, the temperature of the first reaction is 30-100°C, for example, it can be 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C or 95°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0094] Preferably, the time of the first reaction is 0.5-4 h, for example, it can be 0.8 h, 1 h, 1.2 h, 1.5 h, 1.8 h, 2 h, 2.2 h, 2.5 h, 2.8 h, 3 h, 3.2 h, 3.5 h or 3.8 h, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0095] Preferably, the temperature of the second reaction is 30-100°C, for example, it can be 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C or 95°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0096] Preferably, the time of the second reaction is 0.5-4 h, for example, it can be 0.8 h, 1 h, 1.2 h, 1.5 h, 1.8 h, 2 h, 2.2 h, 2.5 h, 2.8 h, 3 h, 3.2 h, 3.5 h or 3.8 h, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0097] Preferably, the mass percentage of NCO groups in the blocked isocyanate crosslinker is ≤0.1%, for example, it may be 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08% or 0.09%, as well as specific values ​​between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range.

[0098] Preferably, the mixed material in step (4) further comprises any one of a wetting agent, a defoaming agent, a leveling agent, an anti-adhesion aid, a film-forming aid, and a lubricant, or a combination of at least two thereof.

[0099] Preferably, based on the mass of the aqueous silicone resin (the mass of the emulsion) as 100%, the mass of the wetting agent, the defoaming agent and the leveling agent are each independently 0.1-0.5%, for example, it can be 0.12%, 0.15%, 0.18%, 0.2%, 0.22%, 0.25%, 0.28%, 0.3%, 0.32%, 0.35%, 0.38%, 0.4% or 0.45%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0100] Preferably, based on the mass of the aqueous silicone resin (the mass of the emulsion) as 100%, the mass of the anti-adhesion additive is 0.1-2%, for example, it can be 0.2%, 0.4%, 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.5%, 1.6% or 1.8%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0101] Preferably, based on the mass of the aqueous silicone resin (the mass of the emulsion) as 100%, the mass of the film-forming aid is 0.1-8%, for example, it can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7% or 7.5%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0102] Preferably, based on the mass of the aqueous silicone resin (the mass of the emulsion) as 100%, the mass of the lubricant is 0.1-2%, for example, it can be 0.2%, 0.4%, 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.5%, 1.6% or 1.8%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0103] The present invention does not specifically limit the specific types of wetting agents, defoaming agents, leveling agents, anti-adhesion aids, film-forming aids, and lubricants, and the present invention is applicable to all of the above-mentioned aids known in the art.

[0104] Preferably, the wetting agent comprises an acetylenic diol wetting agent.

[0105] Preferably, the defoaming agent includes any one of sodium hexametaphosphate, potassium tripolyphosphate, and potassium pyrophosphate, or a combination of at least two of them.

[0106] In a second aspect, the present invention provides a carbon fiber sizing agent, which is prepared by the preparation method described in the first aspect.

[0107] Preferably, the mass retention rate of the carbon fiber sizing agent at 400°C is ≥35%, for example, it can be 35.5%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45% or 46%, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range, and 36-45% is further preferred.

[0108] Exemplarily, the mass retention rate is obtained by testing by the following method: after the carbon fiber sizing agent is heat-treated at 120° C. for 30 min, a thermogravimetric analysis (TGA) test is performed to obtain the mass retention rate at 400° C.

[0109] In a third aspect, the present invention provides a carbon fiber material, comprising a carbon fiber substrate and a coating disposed on the carbon fiber substrate, wherein a raw material for preparing the coating comprises the carbon fiber sizing agent as described in the second aspect.

[0110] Preferably, the mass percentage of the coating in the carbon fiber material is 2-15%, for example, it can be 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13% or 14%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0111] Preferably, the method for preparing the carbon fiber material comprises: placing a carbon fiber matrix in the carbon fiber sizing agent for impregnation and sizing, and heat treating to obtain the carbon fiber material.

[0112] In a fourth aspect, the present invention provides a polymer composite material, comprising a matrix resin and the carbon fiber material as described in the third aspect.

[0113] Optionally, the matrix resin includes polyphenylene sulfide (PPS).

[0114] Compared with the prior art, the present invention has the following beneficial effects:

[0115] In the carbon fiber sizing agent provided by the present invention, through the design and mutual compounding of materials and processes in the preparation method, the carbon fiber sizing agent has good wettability to carbon fiber, can effectively improve the interfacial bonding force between carbon fiber and matrix resin, has excellent high temperature resistance, and can further enhance the cross-linking effect during high temperature processing, improve the wear resistance and high temperature resistance of carbon fiber materials, obtain excellent processing temperature resistance effect, enable it to match and adapt to the high processing temperature (>350°C) of materials such as PPS, and ensure that the carbon fiber material and the polymer composite material have high mechanical strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0116] Figure 1 is the infrared spectrum of the epoxy silicone oil in Example 1;

[0117] Figure 2 is the infrared spectrum of the hydroxyl-containing silicone oil in Example 1;

[0118] Figure 3 is the infrared spectrum of the water-based silicone resin in Example 1;

[0119] Figure 4 This is the infrared spectrum of the blocked isocyanate cross-linking agent in Example 1. DETAILED DESCRIPTION

[0120] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0121] As used herein, the terms "comprises," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0122] "Optionally", "optionally" or "either" means that the subsequently described matter or event can or cannot occur, and that the description includes cases where the event occurs and cases where it does not.

[0123] In the present invention, the features defined as "first" or "second" may include one or more of the features explicitly or implicitly, and are used to distinguish and describe the features, without distinction of order or importance. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0124] In the following specific embodiments of the present invention, the materials for which the preparation methods are not provided are all commercially available chemicals, and the specific information of some materials is shown in Table 1 below:

[0125] Table 1 Material information table

[0126]

[0127] The carbon fiber sizing agent and the preparation method thereof of the present invention will be described in detail below by taking a plurality of embodiments as examples, but the carbon fiber sizing agent and the preparation method thereof of the present invention are not limited to these embodiments.

[0128] Example 1

[0129] A carbon fiber sizing agent and a preparation method thereof, the preparation method comprising the following steps:

[0130] (1) Preparation of epoxy silicone oil

[0131] Glycidyl methacrylate, hydrogenated silicone oil (Mn is 1000), and Custer's catalyst are subjected to hydrosilylation reaction. The molar ratio of glycidyl methacrylate to Si-H groups in hydrogenated silicone oil is 1.05:1. The total mass of glycidyl methacrylate and hydrogenated silicone oil is 100%. The mass of Custer's catalyst is such that the platinum content is 110 ppm. The reaction temperature is 70°C and the reaction time is 8 h. Epoxy silicone oil is obtained. Its infrared spectrum is shown in FIG. Figure 1 As shown, the wave number is 1100 cm -1 The peak is the characteristic peak of the epoxy group, indicating that the epoxy group in glycidyl methacrylate is introduced into the end group of silicone oil through the hydrosilylation reaction to obtain epoxy silicone oil;

[0132] (2) Preparation of hydroxyl-containing silicone oil

[0133] The epoxy silicone oil obtained in step (1), propionic acid and triphenylphosphine catalyst are reacted to make the molar ratio of propionic acid to Si-H group in hydrogen-containing silicone oil be 1.08:1, and the mass of triphenylphosphine is 4% based on the total mass of epoxy silicone oil and propionic acid being 100%; the reaction temperature is 110°C and the reaction time is 5 h to obtain hydroxyl-containing silicone oil, whose infrared spectrum is as shown in FIG. Figure 2 As shown, Figure 1 In comparison, 1100 cm -1 The peak at 3400 cm -1 The peaks nearby are characteristic peaks of hydroxyl groups generated by the reaction, that is, the epoxy groups in the epoxy silicone oil react with the carboxyl groups in the propionic acid to generate hydroxyl groups. The hydroxyl value of the hydroxyl-containing silicone oil was tested by titration, and its hydroxyl value was 71.5 mg KOH / g.

[0134] (3) Preparation of water-based silicone resin

[0135] The hydroxyl-containing silicone oil obtained in step (2) is added to the diisocyanate, so that the molar ratio of the hydroxyl group in the hydroxyl-containing silicone oil to the NCO group in the diisocyanate is 1:1.15, the diisocyanate is HDI and IPDI in a molar ratio of 1:1, and a DBTEL organotin catalyst is added (the mass of the catalyst is 0.1%, based on the total mass of the hydroxyl-containing silicone oil and the diisocyanate being 100%), and the mixture is reacted at 90° C. for 5 h to obtain a first prepolymer;

[0136] The mixture was cooled to 40°C, acetone was added, and then a hydrophilic chain extender DMBA was added, wherein the molar ratio of the hydroxyl group in DMBA to the NCO group in the diisocyanate was 0.05:1, and the mixture was reacted at 60°C for 5 h to obtain a second prepolymer;

[0137] The second prepolymer was neutralized with triethylamine at 40°C for 5 min to make the acid value of the product ≤1 mg KOH / g; then hexamethylenediamine was added to make the molar ratio of the amino group in hexamethylenediamine to the NCO group in the diisocyanate 0.08:1, and the chain extension reaction was carried out at 30°C for 30 min to make the mass percentage of the NCO group in the product ≤0.2%; water and a small amount of ethanol (the mass ratio of water to ethanol was 8:1) were added, and high-speed emulsification was performed for 3 h, and then the ethanol and acetone were removed in vacuum to obtain the water-based silicone resin with a solid content of 30%. The water-based silicone resin was dried and then subjected to infrared testing, and its infrared spectrum was as follows Figure 3 As shown, 1720 cm -1 The peak nearby is the characteristic absorption peak of the C=O bond in the carbamate bond (-NH-CO-O-), 3325 cm -1 The nearby peaks are characteristic absorption peaks of NH bonds in carbamate bonds.

[0138] (4) Preparation of blocked isocyanate crosslinking agent

[0139] The IPDI trimer was added into propylene glycol methyl ether acetate (the mass ratio of IPDI trimer to propylene glycol methyl ether acetate was 7:1) for dissolution, and then polyethylene glycol monomethyl ether 400 was added so that the molar ratio of the NCO group in the IPDI trimer to the hydroxyl group in the polyethylene glycol monomethyl ether 400 was 1:0.18, and the reaction was carried out at 80°C for 3 h to obtain an intermediate product;

[0140] 3,5-dimethylpyrazole was added to the intermediate product, so that the molar ratio of 3,5-dimethylpyrazole to the NCO group in the IPDI trimer was 0.85:1, and the reaction was carried out at 70°C for 2 h, so that the mass percentage of the NCO group in the product was ≤0.1%, and a blocked isocyanate crosslinker was obtained. The blocked isocyanate crosslinker was dried and then subjected to infrared testing, and its infrared spectrum was as shown in FIG. Figure 4 As shown in Figure 2, the stretching vibration peak of the -NCO group (C≡N bond) is at 2240-2280 cm -1 Within the range, Figure 4 Middle 2240-2280 cm -1 There is no obvious characteristic peak, indicating that the -NCO group is blocked.

[0141] (5) Preparation of carbon fiber sizing agent

[0142] In parts by mass, 100 parts of the water-based silicone resin obtained in step (3), 12 parts of the blocked isocyanate cross-linking agent obtained in step (4), 0.2 parts of a wetting agent, 0.3 parts of a defoaming agent, 0.2 parts of a leveling agent, 0.8 parts of an anti-adhesion agent, and 4 parts of a film-forming agent are fully mixed to obtain the carbon fiber sizing agent.

[0143] Example 2

[0144] A carbon fiber sizing agent and a preparation method thereof, the preparation method comprising the following steps:

[0145] (1) Preparation of epoxy silicone oil

[0146] Glycidyl methacrylate, hydrogen-containing silicone oil and Custer catalyst are subjected to a hydrosilylation reaction, wherein the molar ratio of glycidyl methacrylate to Si-H groups in the hydrogen-containing silicone oil is 1.05:1, and the total mass of glycidyl methacrylate and hydrogen-containing silicone oil is 100%, and the mass of the Custer catalyst is such that the platinum content is 80 ppm; the reaction temperature is 80°C, and the reaction time is 5 h, to obtain epoxy silicone oil;

[0147] (2) Preparation of hydroxyl-containing silicone oil

[0148] The epoxy silicone oil obtained in step (1), n-butyric acid and N,N-dimethylbenzylamine are reacted to make the molar ratio of n-butyric acid to Si-H groups in the hydrogen-containing silicone oil be 1.08:1, and the mass of N,N-dimethylbenzylamine is 3% based on the total mass of the epoxy silicone oil and n-butyric acid being 100%; the reaction temperature is 105° C. and the reaction time is 3 h to obtain a hydroxyl-containing silicone oil, and the hydroxyl value thereof is measured by titration to be 70.8 mg KOH / g.

[0149] (3) Preparation of water-based silicone resin

[0150] The hydroxyl-containing silicone oil obtained in step (2) is added to the diisocyanate, so that the molar ratio of the hydroxyl group in the hydroxyl-containing silicone oil to the NCO group in the diisocyanate is 1:1.1, the diisocyanate is HMDI and TMXDI in a molar ratio of 1:1, and a DBTEL organotin catalyst is added (the mass of the catalyst is 0.05%, based on the total mass of the hydroxyl-containing silicone oil and the diisocyanate being 100%), and the mixture is first reacted at 80° C. for 3 h to obtain a first prepolymer;

[0151] The mixture was cooled to 40°C, butanone was added, and then a hydrophilic chain extender DMPA was added, wherein the molar ratio of the hydroxyl group in DMPA to the NCO group in the diisocyanate was 0.04:1, and the mixture was reacted at 70°C for 5 h to obtain a second prepolymer;

[0152] The second prepolymer is reacted with triethylamine at 40°C for 15 minutes to make the acid value of the product ≤1 mg KOH / g; then hexamethylenediamine is added to make the molar ratio of the amino group in hexamethylenediamine to the NCO group in the diisocyanate be 0.07:1, and the chain extension reaction is carried out at 40°C for 15 minutes to make the mass percentage of the NCO group in the product ≤0.2%; water and a small amount of ethanol (the mass ratio of water to ethanol is 10:1) are added, and high-speed emulsification is performed for 5 hours, and then the ethanol and butanone are removed in vacuum to obtain the water-based silicone resin with a solid content of 30%.

[0153] (4) Preparation of blocked isocyanate crosslinking agent

[0154] The HDI trimer was added into propylene glycol methyl ether acetate (the mass ratio of HDI trimer to propylene glycol methyl ether acetate was 7:2) for dissolution, and then polyethylene glycol monomethyl ether 500 was added so that the molar ratio of the NCO group in the HDI trimer to the hydroxyl group in the polyethylene glycol monomethyl ether 500 was 1:0.15, and the reaction was carried out at 80°C for 3 h to obtain an intermediate product;

[0155] 3,5-dimethylpyrazole was added to the intermediate product to make the molar ratio of 3,5-dimethylpyrazole to the NCO group in the HDI trimer be 0.86:1, and the reaction was carried out at 70° C. for 2 h to make the mass percentage of the NCO group in the product ≤0.1%, thereby obtaining a blocked isocyanate crosslinking agent.

[0156] (5) Preparation of carbon fiber sizing agent

[0157] In parts by mass, 100 parts of the water-based silicone resin obtained in step (3), 10 parts of the blocked isocyanate cross-linking agent obtained in step (4), 0.2 parts of a wetting agent, 0.2 parts of a defoaming agent, 0.3 parts of a leveling agent, and 1 part of an anti-adhesion aid are fully mixed to obtain the carbon fiber sizing agent.

[0158] Example 3

[0159] A carbon fiber sizing agent and a preparation method thereof, the preparation method comprising the following steps:

[0160] (1) and (2) are the same as in Example 1 to obtain a hydroxyl-containing silicone oil;

[0161] (3) Preparation of water-based silicone resin

[0162] The hydroxyl-containing silicone oil obtained in step (2) is added to the diisocyanate so that the molar ratio of the hydroxyl group in the hydroxyl-containing silicone oil to the NCO group in the diisocyanate is 1:1.13, the diisocyanate is IPDI, and a DBTEL organotin catalyst is added (the mass of the catalyst is 0.08% based on the total mass of the hydroxyl-containing silicone oil and the diisocyanate being 100%), and the mixture is first reacted at 110° C. for 2 h to obtain a first prepolymer;

[0163] The mixture was cooled to 40°C, butanone was added, and then a hydrophilic chain extender DMPA was added, wherein the molar ratio of the hydroxyl group in DMPA to the NCO group in the diisocyanate was 0.04:1, and the mixture was reacted at 60°C for 4 h to obtain a second prepolymer;

[0164] The second prepolymer is reacted with 2-amino-2-methyl-1-propanol at 40°C for 60 min to make the acid value of the product ≤1 mg KOH / g; then isophorone diamine is added to make the molar ratio of the amino group in the isophorone diamine to the NCO group in the diisocyanate be 0.08:1, and the chain extension reaction is carried out at 40°C for 60 min to make the mass percentage of the NCO group in the product ≤0.2%; water and a small amount of ethanol (the mass ratio of water to ethanol is 10:1) are added, and high-speed emulsification is performed for 5 h, and then the ethanol and butanone are removed in vacuum to obtain the water-based silicone resin with a solid content of 30%.

[0165] (4) Preparation of blocked isocyanate crosslinking agent

[0166] The IPDI trimer was added into propylene glycol methyl ether acetate (the mass ratio of IPDI trimer to propylene glycol methyl ether acetate was 10:1) for dissolution, and then polyethylene glycol monomethyl ether 600 was added so that the molar ratio of the NCO group in the IPDI trimer to the hydroxyl group in the polyethylene glycol monomethyl ether 600 was 1:0.12, and the reaction was carried out at 80°C for 3 h to obtain an intermediate product;

[0167] Methyl ethyl ketone oxime was added to the intermediate product so that the molar ratio of methyl ethyl ketone oxime to the NCO group in the IPDI trimer was 0.88:1, and the reaction was carried out at 60° C. for 2 h so that the mass percentage of the NCO group in the product was ≤0.1%, thereby obtaining a blocked isocyanate crosslinking agent.

[0168] (5) Preparation of carbon fiber sizing agent

[0169] In parts by mass, 100 parts of the water-based silicone resin obtained in step (3), 11 parts of the blocked isocyanate cross-linking agent obtained in step (4), 0.3 parts of a wetting agent, 0.2 parts of a defoaming agent, 0.3 parts of a leveling agent, 1.2 parts of an anti-adhesion agent, and 6 parts of a film-forming agent are fully mixed to obtain the carbon fiber sizing agent.

[0170] Example 4

[0171] A carbon fiber sizing agent and a preparation method thereof, the preparation method comprising the following steps:

[0172] The preparation process of (1) and (2) is the same as that of Example 1 to obtain hydroxyl-containing silicone oil.

[0173] (3) Preparation of water-based silicone resin

[0174] The hydroxyl-containing silicone oil obtained in step (2) is added to the diisocyanate so that the molar ratio of the hydroxyl group in the hydroxyl-containing silicone oil to the NCO group in the diisocyanate is 1:1.13, the diisocyanate is TDI, and a DBTEL organotin catalyst is added (the mass of the catalyst is 0.05%, based on the total mass of the hydroxyl-containing silicone oil and the diisocyanate being 100%), and the mixture is first reacted at 130° C. for 1 h to obtain a first prepolymer;

[0175] The mixture was cooled to 40°C, butanone was added, and then a hydrophilic chain extender DMBA was added, wherein the molar ratio of the hydroxyl group in DMBA to the NCO group in the diisocyanate was 0.05:1, and the mixture was reacted at 70°C for 2 h to obtain a second prepolymer;

[0176] The second prepolymer is reacted with 2-amino-2-methyl-1-propanol at 50°C for 40 min to make the acid value of the product ≤1 mg KOH / g; then ethylenediamine is added to make the molar ratio of the amino group in ethylenediamine to the NCO group in the diisocyanate be 0.07:1, and the chain extension reaction is carried out at 50°C for 40 min to make the mass percentage of the NCO group in the product ≤0.2%; water and a small amount of ethanol (the mass ratio of water to ethanol is 10:2) are added, and high-speed emulsification is performed for 5 h, and then the ethanol and butanone are removed in vacuum to obtain the water-based silicone resin with a solid content of 30%.

[0177] (4) Preparation of blocked isocyanate crosslinking agent

[0178] The IPDI trimer was added into propylene glycol methyl ether acetate (the mass ratio of IPDI trimer to dipropylene glycol methyl ether acetate was 5:1) for dissolution, and then polyethylene glycol monomethyl ether 700 was added so that the molar ratio of the NCO group in the IPDI trimer to the hydroxyl group in the polyethylene glycol monomethyl ether 700 was 1:0.13, and the reaction was carried out at 80°C for 3 h to obtain an intermediate product;

[0179] 3,5-dimethylpyrazole was added to the intermediate product to make the molar ratio of 3,5-dimethylpyrazole to the NCO group in the IPDI trimer be 0.87:1, and the reaction was carried out at 60° C. for 2 h to make the mass percentage of the NCO group in the product ≤0.1%, thereby obtaining a blocked isocyanate crosslinking agent.

[0180] (5) Preparation of carbon fiber sizing agent

[0181] In parts by mass, 100 parts of the water-based silicone resin obtained in step (3), 15 parts of the blocked isocyanate cross-linking agent obtained in step (4), 0.2 parts of a wetting agent, 0.2 parts of a defoaming agent, 0.3 parts of a leveling agent, 0.2 parts of an anti-adhesion agent, and 2 parts of a film-forming agent are fully mixed to obtain the carbon fiber sizing agent.

[0182] Example 5

[0183] (1), (2) and (3) are the same as in Example 1 to obtain a water-based silicone resin having a solid content of 30%.

[0184] (4) Preparation of blocked isocyanate crosslinking agent

[0185] The IPDI trimer was added into dipropylene glycol methyl ether acetate (the mass ratio of IPDI trimer to dipropylene glycol methyl ether acetate was 6:1) for dissolution, and then polyethylene glycol monomethyl ether 800 was added so that the molar ratio of the NCO group in the IPDI trimer to the hydroxyl group in the polyethylene glycol monomethyl ether 800 was 1:0.12, and the reaction was carried out at 70°C for 3 h to obtain an intermediate product.

[0186] 3,5-dimethylpyrazole was added to the intermediate product to make the molar ratio of 3,5-dimethylpyrazole to the NCO group in the IPDI trimer be 0.9:1, and the reaction was carried out at 60° C. for 1 h to make the mass percentage of the NCO group in the product ≤0.1%, thereby obtaining a blocked isocyanate crosslinking agent.

[0187] (5) Preparation of carbon fiber sizing agent

[0188] In parts by mass, 100 parts of the water-based silicone resin obtained in step (3), 12 parts of the blocked isocyanate cross-linking agent obtained in step (4), 0.2 parts of a wetting agent, 0.3 parts of a defoaming agent, 0.2 parts of a leveling agent, 0.8 parts of an anti-adhesion agent, and 4 parts of a film-forming agent are fully mixed to obtain the carbon fiber sizing agent.

[0189] Comparative Example 1

[0190] A carbon fiber sizing agent and a preparation method thereof, which differs from Example 1 only in that the carbon fiber sizing agent does not contain a blocked isocyanate cross-linking agent, and other components, amounts and preparation methods are the same as those in Example 1.

[0191] Comparative Example 2

[0192] A carbon fiber sizing agent and a preparation method thereof, which differs from Example 1 only in that steps (1) and (2) are not performed, and the hydroxyl-containing silicone oil in step (3) is replaced by polytetramethylene ether glycol (PTMEG 2000, Hyosung, South Korea), and other components, amounts and preparation methods are the same as those in Example 1.

[0193] Comparative Example 3

[0194] A carbon fiber sizing agent and a preparation method thereof, which differs from Example 1 only in that steps (1) and (2) are not performed, and the hydroxyl-containing silicone oil used in step (3) is replaced by commercially available hydroxyl silicone oil (JP-203, purchased from Shenzhen Jipeng Silicon Fluoride Materials Co., Ltd.), and the other components, amounts used and preparation methods are the same as those in Example 1.

[0195] The carbon fiber material and the polymer composite material comprising the same according to the present invention will be described in detail below by taking a plurality of application examples as examples, but the carbon fiber material and the polymer composite material comprising the same according to the present invention are not limited to these application examples.

[0196] Application Example 1-5, Comparison Application Example 1-3

[0197] A carbon fiber material and a polymer composite material containing the same, wherein the carbon fiber material comprises a carbon fiber matrix (carbon fiber precursor) and a coating disposed on the carbon fiber matrix, wherein the raw materials for preparing the coating are the carbon fiber sizing agents provided in Examples 1-5 and Comparative Examples 1-3, respectively.

[0198] The polymer composite material includes the aforementioned carbon fiber material and a matrix resin PPS (polyphenylene sulfide, purchased from DIC of Japan), wherein the mass ratio of PPS to the carbon fiber material is 9:1.

[0199] The preparation method of the carbon fiber material and the polymer composite material is as follows:

[0200] (1) impregnating carbon fiber precursor in a carbon fiber sizing agent, sizing, and hot roller treatment to obtain a carbon fiber material, wherein the mass percentage of the coating (sizing amount of the sizing agent) is 4%;

[0201] (2) The carbon fiber material and PPS are put into a twin-screw extruder for melt blending and extrusion granulation. The processing temperature of the twin-screw extruder is 360° C. to obtain the polymer composite material (carbon fiber reinforced PPS).

[0202] The following performance tests are conducted on carbon fiber sizing agents and polymer composite materials:

[0203] (1) Mechanical properties test: The tensile strength and elongation at break of polymer composites were tested using the method in standard GB / T 1040.1-2018;

[0204] (2) Temperature resistance test of carbon fiber sizing agent:

[0205] The carbon fiber sizing agent to be tested was dropped onto a glass slide and then placed in a high-temperature oven at 120°C for 30 min. 8 mg of the sample was added to a peeled crucible for thermogravimetric analysis (TGA) test; the heating program was set: the temperature was increased by 10°C / min from room temperature to 400°C, and the atmosphere was air; the mass retention rate at 400°C was tested, and the higher the retention rate, the better the temperature resistance.

[0206] The test data is shown in Table 2:

[0207] Table 2 Performance test data table

[0208]

[0209] Combined with the test data in Table 2, it can be seen that the present invention, through the design and mutual compounding of materials and processes in the preparation method of the sizing agent, makes the carbon fiber sizing agent have good wettability to the carbon fiber matrix, can improve the interfacial bonding force between the carbon fiber and the matrix resin, and has excellent high temperature resistance, and can further improve the cross-linking effect during high temperature processing. The mass retention rate of the carbon fiber sizing agent at 400°C is 36.2-44.7%, so that the carbon fiber material has excellent wear resistance and high temperature resistance, obtains excellent processing temperature resistance, can match and adapt to the high processing temperature (360-400°C) of materials such as PPS, ensures that the carbon fiber reinforced polymer composite material has high mechanical strength, and the tensile strength of the carbon fiber reinforced polymer composite material is 133-152 MPa.

[0210] The carbon fiber sizing agent of Comparative Example 1 does not contain a blocked isocyanate crosslinking agent, and its temperature resistance is significantly poor, making it difficult to meet the high processing temperature requirements of materials such as PPS. The sizing agent is almost completely lost during the processing process, and it is impossible to provide interfacial crosslinking for the reinforcement of carbon fiber and PPS materials, so the strength improvement is not significant. The carbon fiber sizing agent of Comparative Example 2 does not contain a silicon backbone, and its high temperature resistance is also poor. In the carbon fiber sizing agent of Comparative Example 3, the polyol material used to provide hydroxyl groups is a conventional terminal hydroxyl silicone oil, and the molecular weight distribution of the water-based silicone resin prepared therefrom is uneven, resulting in poor temperature resistance of the sizing agent prepared therefrom, and low strength of the carbon fiber reinforced PPS material.

[0211] The applicant declares that the present invention illustrates the carbon fiber sizing agent and its preparation method and application through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a carbon fiber sizing agent, characterized in that: The preparation method comprises the following steps: (1) subjecting epoxy acrylate monomer to a hydrosilylation reaction with hydrogen-containing silicone oil to obtain epoxy silicone oil; (2) reacting the epoxy silicone oil with a monocarboxylic acid to obtain a hydroxyl-containing silicone oil; (3) reacting the hydroxyl-containing silicone oil, diisocyanate, hydrophilic chain extender, amine chain extender and neutralizer to obtain a water-based silicone resin; (4) mixing the water-based silicone resin with a blocked isocyanate cross-linking agent to obtain the carbon fiber sizing agent; The blocked isocyanate cross-linking agent is prepared by the following method, which comprises: The isocyanate trimer is first reacted with polyethylene glycol monomethyl ether to obtain an intermediate product; The intermediate product is subjected to a second reaction with a blocking agent to obtain the blocked isocyanate cross-linking agent; The isocyanate trimer includes isophorone diisocyanate trimer and / or hexamethylene diisocyanate trimer; the blocking agent includes any one of 3,5-dimethylpyrazole, methyl ethyl ketone oxime, and caprolactam, or a combination of at least two of them.

2. The preparation method according to claim 1, characterized in that: The epoxy acrylate monomer includes glycidyl methacrylate and / or glycidyl acrylate; And / or, the number average molecular weight of the hydrogen-containing silicone oil is 800-2000; and / or, the molar ratio of the epoxy acrylate monomer to the Si—H group in the hydrogen-containing silicone oil is (1-1.2):1; And / or, the hydrosilylation reaction is carried out in the presence of a platinum catalyst; And / or, the temperature of the hydrosilylation reaction is 20-120° C. and the time is 3-10 h.

3. The preparation method according to claim 1, characterized in that: The monocarboxylic acid includes any one of propionic acid, n-butyric acid, and isobutyric acid, or a combination of at least two thereof; And / or, the reaction temperature in step (2) is 80-130° C. and the reaction time is 1-12 h.

4. The preparation method according to claim 1, characterized in that: The diisocyanate includes any one of dicyclohexylmethane diisocyanate, tetramethyl-m-xylylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate, or a combination of at least two thereof; And / or, the hydrophilic chain extender includes any one of dimethylol propionic acid, dimethylol butyric acid, and dimethylol acetic acid, or a combination of at least two thereof; And / or, the amine chain extender includes any one of ethylenediamine, hexamethylenediamine, and isophoronediamine, or a combination of at least two thereof; And / or, the neutralizing agent includes triethylamine, triethanolamine, 2-amino-2-methyl-1-propanol, N,N - Any one or a combination of at least two of dimethylethanolamine.

5. The preparation method according to claim 1, characterized in that: The reaction method in step (3) comprises: The hydroxyl-containing silicone oil is reacted with diisocyanate to obtain a first prepolymer; The first prepolymer and the hydrophilic chain extender undergo a two-stage reaction to obtain a second prepolymer; The second prepolymer is subjected to a neutralization reaction with a neutralizing agent, and then subjected to a chain extension reaction with an amine chain extender, and water is added for emulsification to obtain the water-based silicone resin; The molar ratio of the hydroxyl group in the hydroxyl-containing silicone oil to the NCO group in the diisocyanate is 1:(1.1-1.2); The molar ratio of the NCO group in the diisocyanate, the hydroxyl group in the hydrophilic chain extender, and the amino group in the amine chain extender is 1:(0.01-0.07):(0.04-0.12); The temperature of the first stage reaction is 70-130°C and the time is 1-8 h; The temperature of the second stage reaction is 60-80°C and the time is 1-6 h; The neutralization reaction temperature is 30-50°C and the time is 5-60 min; The temperature of the chain extension reaction is 30-70° C. and the time is 5-60 min.

6. The preparation method according to claim 1, characterized in that: Based on the mass of the water-based silicone resin being 100%, the mass of the blocked isocyanate cross-linking agent is 5-15%; And / or, the molar ratio of the NCO group in the isocyanate trimer, the hydroxyl group in the polyethylene glycol monomethyl ether, and the blocking agent is 1:(0.12-0.18):(0.82-0.93).

7. The preparation method according to claim 1, characterized in that: The mixed material in step (4) further includes any one of a wetting agent, a defoaming agent, a leveling agent, an anti-adhesion aid, a film-forming aid, and a lubricant, or a combination of at least two thereof.

8. A carbon fiber sizing agent, characterized in that: The carbon fiber sizing agent is prepared by the preparation method according to any one of claims 1 to 7.

9. A carbon fiber material, characterized in that: The carbon fiber material comprises a carbon fiber matrix and a coating disposed on the carbon fiber matrix, and the raw materials for preparing the coating comprise the carbon fiber sizing agent as claimed in claim 8.

10. A polymer composite material, characterized in that: The polymer composite material comprises a matrix resin and the carbon fiber material according to claim 9; The base resin includes polyphenylene sulfide.

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