Peptide amic acid water-based emulsion sizing agent as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of synthetic fiber sizing agents, and particularly relates to a peptide amic acid water-based emulsion sizing agent and a preparation method and application thereof. The peptide amic acid water-based emulsion sizing agent provided by the invention is prepared from the following raw materials in parts by mass: 1 to 2 parts of amic acid containing a monoamide group, 2 to 10 parts of a solvent, 0.1 to 0.5 part of a lubricant, 0.1 to 0.5 part of a stabilizer, 86.5 to 96.3 parts of water and 0.5 to 1.5 parts of an emulsifier. The peptide amic acid water-based emulsion sizing agent provided by the invention has good flexibility and wettability, a peptide imide slurry layer formed on the surface of a carbon fiber after thermal imidization is uniform in distribution and high-temperature-resistant, can be applied to a carbon fiber reinforced thermoplastic composite material with relatively high processing temperature, and has high interface bonding strength with a resin matrix.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of synthetic fiber sizing agent, and particularly relates to a peptide amide acid aqueous emulsion sizing agent as well as a preparation method and application thereof. BACKGROUND

[0002] Carbon fiber is a new one-dimensional carbon material with super-high carbon content (90%) and high specific strength and high specific modulus, and has a series of advantages such as high temperature resistance, friction resistance, corrosion resistance, softness and processability, and is the most widely used advanced composite material reinforcing body in the current high-tech field. However, the smooth and inert characteristics of carbon fiber make it difficult to establish effective physical and chemical action between the carbon fiber and the resin matrix, thereby leading to poor interface performance of the carbon fiber reinforced resin matrix composite material. Therefore, the research on improving the bonding strength between the carbon fiber reinforcing body and the resin matrix in the composite material has been concerned by the majority of researchers, and the carbon fiber sizing agent is an important part. Generally, the carbon fiber sizing agent is a mixture of polymers, antistatic agents, stabilizers and other functional additives, which forms a nanometer to micrometer thick sizing layer on the surface of the carbon fiber, on the one hand, plays a protective role of improving the carbon fiber bundling, reducing the amount of hair and improving the wear resistance of the fiber; on the other hand, by introducing polar chemical functional groups on the surface of the carbon fiber, the inert chemical environment is improved, the surface energy of the carbon fiber is improved, and the interfacial bonding strength between the carbon fiber and the resin matrix is improved.

[0003] At present, the commercialized carbon fiber sizing agent on the market is mainly developed for epoxy resin matrix thermosetting composite materials, and the main component is epoxy resin or its modified product, and the temperature resistance grade is generally not more than 250 DEG C. However, for high-performance thermoplastic resin matrix such as polyaryletherketone (PAEK), polyphenylene sulfide (PPS) and polyetherimide (PEI), the forming temperature of the composite material is above 300 DEG C, at this time, the epoxy sizing agent will not only decompose and fail, but also produce small molecule gas defects in the material, reducing the overall performance of the composite material. Therefore, the carbon fiber sizing agent suitable for thermoplastic resin matrix composite material must have high temperature resistance grade.

[0004] Aromatic polyimide is one of the most heat-resistant polymers, and is an ideal material for preparing sizing agent for high-temperature resistant carbon fiber. Related technologies disclose an emulsion type sizing agent prepared by mixing thermoplastic polyimide resin and glycidyl ether type epoxy resin, but the sizing agent prepared by the method has a thermal decomposition temperature of only 300 DEG C, and contains difficult-to-volatilize organic solvent, which is not easy to remove after sizing. Other related technologies use polyamide acid to react with organic base to generate polyamide acid salt with water-soluble characteristics, which avoids the use of a large amount of organic solvent. The main component of the sizing agent prepared by this method is aromatic polyamide acid salt, which has water-soluble characteristics, and can form a polyimide sizing layer with high temperature resistance on the surface of the fiber after subsequent thermal imidization. However, the aromatic polyimide high polymer has large rigidity, and the fiber bundle after sizing has poor flexibility, which will cause the fiber bundle to be difficult to open during subsequent impregnation with resin matrix; in addition, the glass transition temperature of the aromatic polyimide high polymer is generally above 200 DEG C, and generally does not melt in the temperature range of 200-500 DEG C, which is not conducive to spreading the yarn, and in the impregnation process of carbon fiber and resin, the resin melt and the polyimide sizing layer contact in the form of melt-solid, and it is difficult for them to establish strong interactions such as molecular chain mutual diffusion, hydrogen bond and chemical bond, so that the interfacial bonding strength between the carbon fiber and the resin matrix is limited. However, the solution sizing agent is easy to stick to the hot roller during the sizing process, causing the fiber to be easy to fluff, and the carbon fiber after sizing has large brittleness. Therefore, in view of the above problems, it is necessary to develop an emulsion sizing agent which has high temperature resistance, water solubility, strong adhesion, good wettability, and can significantly improve the interfacial performance of carbon fiber reinforced resin matrix composite material. SUMMARY

[0005] Therefore, the present application provides a peptide amide acid aqueous emulsion sizing agent, a preparation method and application thereof. The peptide amide acid aqueous emulsion sizing agent has good flexibility and wettability, and the peptide polyimide sizing layer formed on the surface of the carbon fiber after thermal imidization has uniform distribution, high temperature resistance (5% thermal weight loss temperature is higher than 400 DEG C), strong adhesion, and can be applied to carbon fiber reinforced thermoplastic composite materials with high processing temperature, has low melting temperature (lower than 300 DEG C), and has high interfacial bonding strength with the resin matrix.

[0006] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions: The present application provides a peptide amide acid aqueous emulsion sizing agent, and the preparation raw materials include, in mass fraction: amide acid containing a single amide group 1-2 parts, solvent 2-10 parts, lubricant 0.1-0.5 parts, Stabilizer 0.1-0.5 parts, Water 86.5-96.3 parts, Emulsifier 0.5-1.5 parts.

[0007] Preferably, the preparation method of the amide acid containing a single amide group comprises the following steps: In a protective atmosphere, aromatic diamine, aromatic monomer and polar aprotic solvent are mixed to carry out condensation reaction to obtain amide acid containing a single amide group.

[0008] Preferably, the aromatic diamine is one or more of 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 2,4'-diaminodiphenyl ether, 4,4'-bis(3-aminophenoxy)benzophenone, 4,4'-bis(4-aminophenoxy)benzophenone, 3,4'-bis(3-aminophenoxy)benzophenone, 3,4'-bis(4-aminophenoxy)benzophenone, 3,3'-bis(3-aminophenoxy)benzophenone, 3,3'-bis(4-aminophenoxy)benzophenone, p-phenylenediamine and m-phenylenediamine.

[0009] Preferably, the aromatic monomer is phthalic anhydride.

[0010] Preferably, the lubricant is one or more of polyoxyethylene ether, fatty acid polyoxyethylene ether, polyoxyethylene and polyoxypropylene ether mixture, butyl stearate, higher fatty amine, higher fatty alcohol and higher fatty ester; the higher fatty amine, higher fatty alcohol and higher fatty ester refer to organic matter with carbon atoms ≥10.

[0011] Preferably, the stabilizer is one or more of ammonium chloride, ammonium sulfate and ammonium nitrate.

[0012] Preferably, the emulsifier is a surfactant; the surfactant includes one or more of sodium dodecylbenzenesulfonate, sorbitan monostearate polyethylene ether, alkylphenol polyoxyethylene ether, castor oil polyethylene ether, fatty acid and ethylene oxide polyadduct, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan palmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene monolaurate, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether and polyoxyethylene fatty acid amino ether.

[0013] The present application also provides a preparation method of the peptide amide acid aqueous emulsion sizing agent described in the above technical solution, comprising the following steps: Mixing the amide acid containing a single amide group and a solvent to obtain an amide acid solution containing a single amide group; Mixing the amide acid solution containing a single amide group, a lubricant, a stabilizer, an emulsifier and part of water, and diluting with the remaining water after dispersion emulsification to obtain the peptide amide acid aqueous emulsion sizing agent.

[0014] The application also provides application of the peptide amide acid aqueous emulsion sizing agent in the above technical solution or the peptide amide acid aqueous emulsion sizing agent prepared by the preparation method in the above technical solution in sizing of carbon fibers.

[0015] The application also provides a method for sizing carbon fibers, which comprises the following steps: After the unsized carbon fibers are immersed in the sizing agent, drying, thermal imidization and silk collection are sequentially performed to complete the sizing; The sizing agent is the peptide amide acid aqueous emulsion sizing agent in the above technical solution or the peptide amide acid aqueous emulsion sizing agent prepared by the preparation method in the above technical solution.

[0016] The application provides a peptide amide acid aqueous emulsion sizing agent, and preparation raw materials include, in mass fraction, 1-2 parts of amide acid containing a single amide group, 2-10 parts of a solvent, 0.1-0.5 parts of a lubricant, 0.1-0.5 parts of a stabilizer, 86.5-96.3 parts of water and 0.5-1.5 parts of an emulsifier.

[0017] Compared with the related art, the application has the following beneficial effects: 1. After the amide acid containing a single amide group in the application is sized, aromatic peptide imide is formed through thermal imidization, the high-temperature resistance is excellent, and the amide acid can be applied to carbon fiber reinforced thermoplastic composite materials with high processing temperature.

[0018] 2. The sizing layer of the peptide amide acid aqueous emulsion sizing agent provided by the application mainly contains small molecule peptide imide compounds, and there is no macromolecular chain, so that the carbon fiber bundle after sizing has both bundling property and flexibility, and is more conducive to the subsequent impregnation process of the carbon fiber and the thermoplastic resin matrix.

[0019] 3. The aromatic peptide imide small molecule sizing layer prepared by the application has the characteristics of being meltable and having low melting temperature, and in the process of impregnation of the fiber bundle and the resin matrix, the sizing layer melt and the thermoplastic resin melt can fully interact, thereby effectively improving the interfacial bonding strength of the composite material.

[0020] 4. The peptide amide acid aqueous emulsion sizing agent provided by the application is an aqueous emulsion of amide acid containing a single amide group in the sizing stage, has the characteristics of good adhesion effect and uniform sizing, is not easy to stick to the hot roller in the sizing process, is convenient for simplifying the process, and the main solvent is water, and has the characteristics of being green, environmentally friendly and non-toxic. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The infrared absorption spectrum of the peptide imide obtained after drying and thermal imidization of the peptide amic acid aqueous emulsion sizing agent prepared in Example 1; Figure 2 The thermogravimetric analysis curve of the peptide imide obtained after drying and thermal imidization of the peptide amic acid aqueous emulsion sizing agent prepared in Example 1; Figure 3 The differential scanning calorimetric analysis curve of the peptide imide obtained after drying and thermal imidization of the peptide amic acid aqueous emulsion sizing agent prepared in Example 1; Figure 4 The surface morphology diagram of the T800 grade carbon fiber after sizing with the peptide amic acid aqueous emulsion sizing agent prepared in Example 1. DETAILED DESCRIPTION

[0022] The present application provides a peptide amic acid aqueous emulsion sizing agent, and the preparation raw materials include, in mass fraction: an amic acid containing a single amide group 1-2 parts, a solvent 2-10 parts, a lubricant 0.1-0.5 parts, a stabilizer 0.1-0.5 parts, water 86.5-96.3 parts, an emulsifier 0.5-1.5 parts.

[0023] Unless otherwise specified, the present application does not have special requirements for the source of the raw materials used, and commercially available products known to those skilled in the art can be used.

[0024] The present application provides a peptide amic acid aqueous emulsion sizing agent, and the preparation raw materials include, in mass fraction: an amic acid containing a single amide group 1-2 parts, specifically 1-1.5 parts in the specific embodiment.

[0025] As an embodiment, the molecular weight of the amic acid containing a single amide group is 500-5000, specifically 1000-5000 in the specific embodiment.

[0026] As an embodiment, the preparation method of the amic acid containing a single amide group includes the following steps: Mixing aromatic diamine, aromatic mono-anhydride and polar aprotic solvent in a protective atmosphere to perform condensation reaction to obtain an amic acid containing a single amide group.

[0027] As an embodiment, the protective gas comprises argon or nitrogen, and specifically nitrogen; the aromatic diamine is one or more of 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 2,4'-diaminodiphenyl ether, 4,4'-bis(3-aminophenoxy)benzophenone, 4,4'-bis(4-aminophenoxy)benzophenone, 3,4'-bis(3-aminophenoxy)benzophenone, 3,4'-bis(4-aminophenoxy)benzophenone, 3,3'-bis(3-aminophenoxy)benzophenone, 3,3'-bis(4-aminophenoxy)benzophenone, p-phenylenediamine and m-phenylenediamine, and another embodiment is one or more of 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether and 4,4'-bis(3-aminophenoxy)benzophenone, and specifically 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether or 1,3-bis(3-aminophenoxy)benzene.

[0028] As an embodiment, the aromatic monoanhydride is phthalic anhydride; the molar ratio of the aromatic diamine to the aromatic monoanhydride is 1:1.5-2.59, and specifically 1:2; the polar aprotic solvent is one or more of N-methylpyrrolidone, dimethyl sulfoxide, N,N'-dimethylacetamide and N,N'-dimethylformamide, and specifically N,N'-dimethylacetamide; the ratio of the mass of the aromatic diamine to the volume of the polar aprotic solvent is (200-300) g:(2-3) L, and specifically 200.24 g:2.12 L or 292.33 g:2.35 L; and the aromatic monoanhydride is purified by sublimation before use. The polar aprotic solvent in the present application can dissolve the aromatic diamine and the aromatic monoanhydride used, and the poor solvent cannot dissolve the amic acid containing a monoamide group synthesized.

[0029] As an embodiment, the temperature of the condensation reaction is 0-25°C, and specifically 0°C, and the time is 6-24 h, and specifically 12 h; the condensation reaction is carried out under stirring; and the stirring speed is 150-300 rpm, and specifically 150-250 rpm.

[0030] A continuous nitrogen or argon gas flow is used to purge during the condensation reaction, and the reaction is carried out in an ice water bath to avoid oxidation of the aromatic diamine.

[0031] As an embodiment, after the condensation reaction, the product of the condensation reaction is mixed with a poor solvent, the amide acid containing a single amide group is precipitated, and then solid-liquid separation, washing and drying are sequentially performed to obtain an amide acid powder containing a single amide group; the poor solvent is deionized water and / or alcohol, and another embodiment is deionized water or a mixed solution of deionized water and alcohol, and a specific embodiment is a mixed solution of deionized water and alcohol; the alcohol includes methanol and / or ethanol, and a specific embodiment is ethanol; the volume ratio of deionized water to alcohol is 8-9:1, and a specific embodiment is 9:1; the solid-liquid separation is reduced pressure suction filtration; the pressure of the reduced pressure suction filtration is 0-0.2 MPa, and a specific embodiment is 0.1 MPa; the reagent used for washing is a poor solvent; the number of times of washing is 6-8 times, and a specific embodiment is 6 times; the drying includes thermal evaporation and / or vacuum freeze sublimation, and a specific embodiment is vacuum freeze sublimation; the temperature of the thermal evaporation is 100-120°C, and the time is 72-96 h; the temperature of the vacuum freeze sublimation is -20 to -50°C, and a specific embodiment is -40°C; the pressure is 5.0-10.0 Pa, and a specific embodiment is 8 Pa; and the time is 72-96 h, and a specific embodiment is 72 h. The temperature for drying is set in the above range to avoid imidization of the amide acid containing a single amide group due to too high temperature.

[0032] The peptide amide acid aqueous emulsion sizing agent provided by the application includes, in terms of mass fraction based on 1 mass part of the amide acid containing a single amide group, 2-10 parts of a solvent, and a specific embodiment is 3-5 parts.

[0033] As an embodiment, the solvent is one or more of butanone, acetone, ethyl acetate, tetrahydrofuran, N-methyl pyrrolidone, dimethyl sulfoxide, N,N'-dimethylacetamide and N,N'-dimethylformamide, and a specific embodiment is N,N'-dimethylformamide. A slight excess of the solvent is beneficial to improve the storage stability of the amide acid slurry containing a single amide group.

[0034] The peptide amide acid aqueous emulsion sizing agent provided by the application includes, in terms of mass fraction based on 1 mass part of the amide acid containing a single amide group, 0.1-0.5 parts of a lubricant, and a specific embodiment is 0.1-0.3 parts.

[0035] As an embodiment, the lubricant is one or more of polyoxyethylene ether, fatty acid polyoxyethylene ether, polyoxyethylene and polyoxypropylene ether mixture, butyl hard acid ester, higher fatty amine, higher fatty alcohol and higher fatty ester, another embodiment is one or more of polyoxyethylene ether, fatty acid polyoxyethylene ether, polyoxyethylene and polyoxypropylene ether mixture and butyl hard acid ester, and in a specific embodiment, the lubricant is polyoxyethylene ether; the higher fatty amine, higher fatty alcohol and higher fatty ester refer to organic compounds with carbon atoms ≥ 10. The lubricant in the present application is used to improve the wettability of fibers and emulsion.

[0036] The peptide amide acid aqueous emulsion sizing agent provided by the present application comprises, in terms of mass fraction based on 1 mass part of the amide acid containing a single amide group: 0.1-0.5 parts of a stabilizer, and in a specific embodiment, 0.1-0.3 parts.

[0037] As an embodiment, the stabilizer is one or more of ammonium chloride, ammonium sulfate and ammonium nitrate, and in a specific embodiment, the stabilizer is ammonium chloride. The ammonium chloride used in the present application has strong hydrogen bonding and ionic interaction between the molecules of the stabilizer and the molecules of the resin and water molecules, which is used to enhance the storage stability and avoid demulsification caused by layering.

[0038] The peptide amide acid aqueous emulsion sizing agent provided by the present application comprises, in terms of mass fraction based on 1 mass part of the amide acid containing a single amide group: 86.5-96.3 parts of water, and in a specific embodiment, 87-96.3 parts.

[0039] As an embodiment, the water is deionized water.

[0040] The peptide amide acid aqueous emulsion sizing agent provided by the present application comprises, in terms of mass fraction based on 1 mass part of the amide acid containing a single amide group: 0.5-1.5 parts of an emulsifier, and in a specific embodiment, 0.5-1 part.

[0041] As an embodiment, the emulsifier is a surfactant; the surfactant includes one or more of sodium dodecyl benzene sulfonate, sorbitan monostearate polyethylene ether, alkyl phenol polyoxyethylene ether, castor oil polyethylene ether, fatty acid and ethylene oxide polyadduct, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan palmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene monolaurate, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether and polyoxyethylene fatty acid amino ether, and in a specific embodiment, the emulsifier is sodium dodecyl benzene sulfonate.

[0042] The present application also provides a preparation method of the peptide amide acid aqueous emulsion sizing agent described in the above technical solutions, which comprises the following steps: mixing the amido acid containing a single amide group and the solvent to obtain an amido acid containing a single amide group solution; mixing the amido acid containing a single amide group solution, the lubricant, the stabilizer, the emulsifier and part of the water, dispersing and emulsifying, then adding the rest of the water to dilute to obtain the aqueous emulsion sizing agent of the peptide amido acid.

[0043] As an embodiment, the mixing of the amido acid containing a single amide group and the solvent is carried out under stirring; the stirring temperature is 50-60℃, specifically 55℃, the stirring time is 2-3h, specifically 2h, and the stirring speed is 300-1000rpm, specifically 600rpm.

[0044] As an embodiment, the mixing of the amido acid containing a single amide group solution, the lubricant, the stabilizer, the emulsifier and water is as follows: mixing the emulsifier and part of the water to obtain an emulsifier aqueous solution; adding the lubricant, the stabilizer and the emulsifier aqueous solution into the amido acid containing a single amide group solution; mixing the emulsifier and part of the water under stirring; the stirring speed is 600-2000rpm, specifically 1000-1500rpm.

[0045] As an embodiment, the mass ratio of the part of the water to the rest of the water is 1-10:90-99, specifically 6:94.

[0046] As an embodiment, the dispersing and emulsifying speed is 10000-20000rpm, specifically 15000rpm, and the time is 1-2h, specifically 1.5h.

[0047] The aromatic diamine and phthalic anhydride or its derivative are fully reacted in the present application to obtain an amic acid solution containing a monoamide group; the amic acid solution containing a monoamide group is precipitated in a poor solvent, and after the residual solvent is fully removed, an amic acid solid powder containing a monoamide group is obtained; the amic acid powder containing a monoamide group is dissolved in a solvent to obtain a uniform and transparent amic acid solution containing a monoamide group; a wetting agent and a stabilizer are added to the amic acid solution containing a monoamide group, stirred and dissolved, and then deionized water containing an emulsifier is added and sheared and emulsified, and after full emulsification, deionized water is added for dilution to obtain a peptide amic acid aqueous emulsion sizing agent; the carbon fiber immersed in the sizing agent is subjected to a dehydration and thermal imidization step in a high-temperature furnace to complete the sizing of the carbon fiber. The sizing agent prepared by the method forms a sizing layer on the surface of the carbon fiber, and the effective component of the sizing layer is an aromatic peptide imide, so the sizing layer has a high temperature resistance grade; unlike high molecular polyimide, the small molecule peptide imide prepared by the method avoids the problem of high rigidity of the molecular chain of high molecular polyimide, so the flexibility of the sized carbon fiber is increased, and the sizing layer has a low melting temperature, which is beneficial to yarn spreading and facilitates the subsequent impregnation process of the carbon fiber and the resin matrix; unlike a solution sizing agent, the emulsion sizing agent prepared by the method improves the problem of uneven sizing and easy sticking to the hot roller of the solution sizing agent, has better processability in industrial production, and is not easy to leave resin on the guide roller, thereby reducing the risk of fiber damage, while the solution sizing agent is easy to leave on the guide roller, affecting the processing performance of the fiber; the emulsion sizing agent contains an emulsifier, which can reduce the surface tension of the emulsion, thereby improving the wettability of the carbon fiber and helping to form a uniform sizing film, while the wettability of the solution sizing agent is poor, making it difficult to form a uniform sizing film; the emulsion sizing agent can also improve the bunching and surface wettability of the carbon fiber and enhance the interfacial adhesion between the fiber and the resin. The quality composition of the sizing agent prepared by the method is: 1-2% amic acid containing a monoamide group, 2-10% solvent, 0.1-0.5% lubricant, 0.1-0.5% stabilizer, 86.5-96.3% water, and 0.5-1.5% emulsifier. The sizing agent can not only protect the carbon fiber, increase its flexibility and improve its processability, but also effectively enhance the interfacial bonding strength between the carbon fiber and the resin matrix in the composite material, especially in high-performance thermoplastic composite materials with high forming temperature; the prepared emulsion sizing agent is uniform in sizing, has strong adhesion, and the solvent is water, which is approximately zero pollution in the application process, and has the characteristics of simple preparation, strong process adaptability, reliable effect, green and environmental friendliness.

[0048] The present application also provides the application of the peptide amic acid aqueous emulsion sizing agent in the above technical solution and the peptide amic acid aqueous emulsion sizing agent prepared by the preparation method in the above technical solution in the sizing of carbon fiber.

[0049] The present application also provides a method for sizing carbon fiber, comprising the following steps: After the un-sized carbon fiber is dipped in the sizing agent, drying, thermal imidization and fiber collection are sequentially performed to complete the sizing; The sizing agent is the peptide amide acid aqueous emulsion sizing agent in the technical solution and the peptide amide acid aqueous emulsion sizing agent prepared by the preparation method.

[0050] As an embodiment, the un-sized carbon fiber is a carbon fiber from which the sizing agent is removed; the carbon fiber is a high-strength series carbon fiber or a high-modulus series carbon fiber, and in a specific embodiment, the carbon fiber is a high-strength series carbon fiber; the high-strength series carbon fiber includes T300, T700, T800 or T1000, and in a specific embodiment, the high-strength series carbon fiber is T800; the high-modulus series carbon fiber includes M35JB, M40JB, M46JB, M50JB or M35JB, and in a specific embodiment, the high-modulus series carbon fiber is M40JB; the dipping process is as follows: the sizing agent is introduced into a sizing tank, the un-sized carbon fiber is dipped into the sizing agent at a speed of 50 m / h, and after the dipping is completed, the un-sized carbon fiber is pulled out of the sizing tank; in a specific embodiment, the speed is 50 m / h; the drying temperature is 100-120 DEG C, and in a specific embodiment, the temperature is 120 DEG C; the drying time is 1-2 h, and in a specific embodiment, the time is 1 h; the thermal imidization temperature is 280-300 DEG C, and in a specific embodiment, the temperature is 300 DEG C; the thermal imidization time is 2-3 h, and in a specific embodiment, the time is 2 h. In the present application, the amide acid containing a single amide group distributed on the surface of the carbon fiber forms a peptide imide sizing layer after thermal imidization, and has the characteristics of uniform distribution, chemical stability and long-term storage. The peptide imide sizing layer has the characteristic of low melting temperature, and its application advantages are as follows: in the pre-impregnation process of the carbon fiber and the thermoplastic resin matrix, the sizing layer in a molten state and the thermoplastic resin melt can fully contact and establish chemical and physical action, and can effectively improve the interfacial bonding strength between the carbon fiber and the thermoplastic resin.

[0051] The technical solutions in the present application will be clearly and completely described below in combination with the embodiments in the present application, but they should not be understood as limitations to the protection scope of the present application.

[0052] Example 1 Take 200.24 g of 3,4'-diaminodiphenyl ether, under the condition of continuous nitrogen purging and 150 rpm stirring, add it into 2.12 L of N,N'-dimethylacetamide (DMAc), after completely dissolved, add 296.24 g of phthalic anhydride, the condensation reaction is continuously carried out at 0℃ for 12 h, to obtain a homogeneous transparent amic acid solution containing a single amide group, then, pour the DMAc solution of amic acid containing a single amide group into 20 L of deionized water, precipitate white sediment, after vacuum filtration under 0.1 MPa pressure, deionized water washing 6 times, vacuum freeze sublimation at a vacuum degree of 8 Pa and -40℃ for 72 h, white solid powder of amic acid containing a single amide group is obtained; Take another 50 g of amic acid powder containing a single amide group and add it into 150 g of N,N'-dimethylformamide, dissolve it at 55℃ under 600 rpm stirring for 1.5 h, to obtain a colorless transparent amic acid solution containing a single amide group; then take 5 g of polyoxyethylene ether and 5 g of ammonium chloride and add them into the amic acid solution containing a single amide group, add 25 g of sodium dodecylbenzenesulfonate into 300 g of deionized water and stir it uniformly at 1000 rpm, then slowly add the amic acid solution containing a single amide group and stir it in a dispersion emulsifier at a speed of 15000 rpm for 1.5 h, then add 4515 g of deionized water, to obtain a 1wt% peptide amic acid aqueous emulsion sizing agent.

[0053] Example 2 Take 200.24 g of 3,4'-diaminodiphenyl ether, under the condition of continuous nitrogen purging and 150 rpm stirring, add it into 2.12 L of N,N'-dimethylacetamide (DMAc), after completely dissolved, add 296.24 g of phthalic anhydride, the condensation reaction is continuously carried out at 0℃ for 12 h, to obtain a homogeneous transparent amic acid solution containing a single amide group, then, pour the DMAc solution of amic acid containing a single amide group into 20 L of deionized water, precipitate white sediment, after vacuum filtration under 0.1 MPa pressure, deionized water washing 6 times, vacuum freeze sublimation at a vacuum degree of 8 Pa and -40℃ for 72 h, white solid powder of amic acid containing a single amide group is obtained; Take 50 g of the amide acid powder containing a single amide group and add it to 150 g of N,N'-dimethylformamide. Stir at 600 rpm at 55°C for 1.5 h to obtain a light yellow amide acid solution containing a single amide group. Then take 5 g of polyoxyethylene ether and 5 g of ammonium chloride and add them to the amide acid solution containing a single amide group. Add 25 g of sodium dodecylbenzenesulfonate to 300 g of deionized water and stir at 1000 rpm until uniform. Then slowly add the amide acid solution containing a single amide group and stir it in a dispersion emulsifier at a speed of 15000 rpm for 1.5 h. Then add 4515 g of deionized water to obtain a 1 wt% aqueous emulsion sizing agent of the peptide amide acid.

[0054] Example 3 Take 292.33 g of 1,3-bis(3-aminophenoxy)benzene and add it to 2.35 L of N,N'-dimethylacetamide (DMAc) under continuous nitrogen purging and stirring at 150 rpm. After complete dissolution, add 296.24 g of phthalic anhydride and continue the condensation reaction at 0°C for 12 h to obtain a homogeneous transparent amide acid solution containing a single amide group. Then pour the DMAc solution of the amide acid containing a single amide group into 20 L of deionized water to precipitate a white solid. After vacuum filtration under a pressure of 0.1 MPa, washing with deionized water 6 times, and vacuum freeze sublimation at a vacuum degree of 8 Pa at -40°C for 72 h, obtain white solid powder of the amide acid containing a single amide group. Take 50 g of the amide acid powder containing a single amide group and add it to 150 g of N,N'-dimethylformamide. Stir at 600 rpm at 55°C for 1.5 h to obtain a light yellow amide acid solution containing a single amide group. Then take 5 g of polyoxyethylene ether and 5 g of ammonium chloride and add them to the amide acid solution containing a single amide group. Add 25 g of sodium dodecylbenzenesulfonate to 300 g of deionized water and stir at 1000 rpm until uniform. Then slowly add the amide acid solution containing a single amide group and stir it in a dispersion emulsifier at a speed of 15000 rpm for 1.5 h. Then add 4515 g of deionized water to obtain a 1 wt% aqueous emulsion sizing agent of the peptide amide acid.

[0055] Example 4 Take 292.33g of 1,3-bis(4-aminophenoxy)benzene, under the condition of continuous nitrogen purging and 150rpm stirring, add it into 2.35L of N,N'-dimethylacetamide (DMAc), after completely dissolved, add 296.24g of phthalic anhydride, the condensation reaction is carried out at 0℃ for 12h, a homogeneous transparent amic acid solution is obtained, then, pour the amic acid DMAc solution into 20L of deionized water, a white precipitate is separated out, after vacuum filtration under 0.1MPa pressure, deionized water washing for 6 times, vacuum freeze sublimation at the condition of vacuum degree of 8Pa and-40℃ for 72h, a white amic acid solid powder is obtained; Take another 50g of amic acid powder and add it into 150g of N,N'-dimethylformamide, stir and dissolve at 55℃ for 1.5h at 600rpm, a colorless transparent amic acid solution is obtained; then take 5g of polyoxyethylene ether and 5g of ammonium chloride and add them into the amic acid solution, add 25g of sodium dodecylbenzenesulfonate into 300g of deionized water and stir uniformly at 1000rpm, then slowly add the amic acid solution and stir it in a dispersion emulsifier at 15000rpm for 1.5h, then add 4515g of deionized water, a 1wt% peptide amic acid aqueous emulsion sizing agent is obtained.

[0056] Comparative Example 1 Take 200.24g of 3,4'-diaminodiphenyl ether, under the condition of continuous nitrogen purging and 600rpm stirring, add it into 2.12L of N,N'-dimethylacetamide (DMAc), after completely dissolved, add 322.23g of 3,3',4,4'-benzophenonetetracarboxylic dianhydride, the condensation reaction is carried out at 0℃ for 12h, a homogeneous transparent polyamic acid solution is obtained, then, pour the polyamic acid DMAc solution into 20L of deionized water, a light yellow precipitate is separated out, after vacuum filtration under 0.1MPa pressure, deionized water washing for 6 times, vacuum freeze sublimation at the condition of vacuum degree of 8Pa and-40℃ for 72h, a light yellow polyamic acid solid powder is obtained; Take another 50g of polyamic acid powder and add it into 150g of N,N'-dimethylformamide, stir and dissolve at 55℃ for 1.5h at 600rpm, a light yellow polyamic acid solution is obtained; then take 5g of polyoxyethylene ether and 5g of ammonium chloride and add them into the polyamic acid solution, add 25g of sodium dodecylbenzenesulfonate into 300g of deionized water and stir uniformly at 1000rpm, then slowly add the polyamic acid solution and stir it in a dispersion emulsifier at 15000rpm for 1.5h, then add 4515g of deionized water, a 1wt% high polymer polyamic acid aqueous emulsion sizing agent is obtained.

[0057] Application Example 1 The peptide amide acid aqueous emulsion sizing agent prepared in Example 1 was poured into a sizing tank, and the de-sized commercial T800-grade carbon fiber bundle was pulled into the sizing agent at a speed of 50 m / h, pulled out of the sizing tank after impregnation, and then dried in a drying oven at 120°C for 1 h, and then subjected to thermal imidization in a high-temperature furnace at 300°C for 2 h to form a peptide imide sizing layer, and finally the sizing of the carbon fiber was completed by using a yarn collector.

[0058] Application Examples 2-4 The difference from Example 1 is that the peptide amide acid aqueous emulsion sizing agent prepared in Example 1 is replaced by the peptide amide acid aqueous emulsion sizing agent prepared in Examples 2-4, respectively.

[0059] Comparative Application Example 1 The difference from Example 1 is that the peptide amide acid aqueous emulsion sizing agent prepared in Example 1 is replaced by the high polymer polyamide acid aqueous emulsion sizing agent prepared in Comparative Example 1.

[0060] Performance Test (1) Test 1: The heat resistance of the peptide imide sizing layer synthesized in Application Examples 1-4 was analyzed by using a DISCOVERY TGA550 thermal gravimetric analyzer, and the test conditions were as follows: air atmosphere, atmosphere flow rate 30 mL / min, and temperature rising rate 10°C / min. The specific test results are shown in Table 1.

[0061] Test 2: The melting temperature of the peptide imide sizing layer synthesized in Application Examples 1-4 was tested by using a TA DSC 250 differential scanning calorimeter, and the test conditions were as follows: nitrogen atmosphere and temperature rising rate 10°C / min. The specific test results are shown in Table 1.

[0062] Test 3: The surface morphology of the sized carbon fiber prepared in Application Examples 1-4 was observed by using a Regulus 8230 field emission scanning electron microscope, and the sizing layer distribution uniformity was evaluated. The carbon fiber surface obtained a continuous and uniform sizing layer, which was excellent in distribution uniformity, and the carbon fiber surface sizing layer was discontinuous or had obvious accumulation, which was poor in distribution. The specific test results are shown in Table 1.

[0063] Test 4: Referring to a high-performance carbon fiber sag automatic testing device and method in a patent CN 109596051 A, 500 mm of the sized carbon fiber bundle prepared in Application Examples 1-4 was cut, and one end of the bundle was laid flat on a flat table, and the other end was stretched out of the table by 200 mm to hang in the air, so that it naturally fell. A measuring ruler was used to measure the horizontal distance of the hanging end of the carbon fiber from the table, and the smaller the horizontal distance, the better the flexibility of the fiber bundle. Comparative Application Examples 1-4 and a commercial T800-grade carbon fiber with an epoxy-based sizing agent were used as a comparison, and the specific test results are shown in Table 1.

[0064] Test 5: The interfacial bonding strength (IFSS) between the sized carbon fibers in application examples 1-4 and the thermoplastic resin polyaryletherketone was tested by microsphere debonding method. The application examples 1-4 and the commercial T800 grade carbon fiber with epoxy sizing agent were used as comparison. The test results are shown in Table 1.

[0065] Table 1 Test results

[0066] According to the test results in Table 1, the following conclusions can be drawn: First, the flexibility of the peptide amide acid aqueous emulsion sizing agent provided by the present application is significantly better. The overhanging distance of the carbon fiber sized by the peptide amide acid aqueous emulsion sizing agent provided by the present application is about 124-145 mm, which is reduced by about 70 mm compared with the high polymer polyamide acid aqueous emulsion sizing agent in comparative application example 1. It can be seen that the flexibility of the carbon fiber sized by the peptide amide acid aqueous emulsion sizing agent prepared by the present application is significantly better than that of the high polymer polyamide acid aqueous emulsion sizing agent in comparative application example 1, and is comparable to that of the commercially available T800 grade sized carbon fiber.

[0067] Second, the peptide amide acid aqueous emulsion sizing agent provided by the present application can improve the interfacial bonding strength between the resin matrix. The interfacial bonding strength between the carbon fiber sized by the peptide amide acid aqueous emulsion sizing agent of the present application and the resin matrix reaches more than 80 MPa, while the interfacial bonding strength between the carbon fiber sized by the sizing agent of comparative application example 1 or the commercially available sized carbon fiber T800 and the resin matrix is about 60-70 MPa. It can be seen that the peptide amide acid aqueous emulsion sizing agent provided by the present application can significantly improve the interfacial bonding strength between the carbon fiber and the resin matrix (especially the thermoplastic resin matrix).

[0068] Third, the heat resistance of the peptide amide acid aqueous emulsion sizing agent provided by the present application is better. The sizing layer on the surface of the commercially available T800 grade carbon fiber is thermally decomposed and fails at 200℃, which cannot adapt to the high temperature forming process of the composite material. However, the heat resistance of the peptide amide acid aqueous emulsion sizing agent of the present application is higher than 400℃, which can better adapt to the high temperature forming process required by the resin matrix with higher melting point. However, the high polymer polyamide acid in comparative application example 1 is a high polymer with large molecular weight and high decomposition temperature.

[0069] (2) Figure 1 The infrared absorption spectrum of the peptide imide obtained after drying and thermal imidization of the peptide amide acid aqueous emulsion sizing agent prepared in Example 1; from the figure, the absorption peaks at 1783 cm -1 , 1722 cm -1 and 715 cm -1 belong to the asymmetric stretching vibration, symmetric stretching vibration and bending vibration of C=O in aromatic imide, respectively, and 1391 cm-1 The peak at 1500 cm -1 and 1450 cm -1 is attributed to the vibration absorption peak of benzene ring skeleton, and the vibration absorption peak of C-O-C at 1239 cm -1 . The presence of these characteristic peaks indicates that the aromatic PI is successfully prepared, and it has similar characteristic groups such as aryl, ether bond and ketone group in structure to PAEK.

[0070] Figure 2 The thermogravimetric analysis curve of the peptide imide obtained after drying and thermal imidization of the peptide amide acid aqueous emulsion sizing agent prepared in Example 1; from the figure, it can be seen that the 5 wt% thermal weight loss temperature is 408℃, higher than 400℃, and when it is used as a CF sizing layer, it completely meets the forming temperature requirements of CF / PAEK composite materials.

[0071] Figure 3 The differential scanning calorimetry analysis curve of the peptide imide obtained after drying and thermal imidization of the peptide amide acid aqueous emulsion sizing agent prepared in Example 1; from the figure, it can be seen that the melting temperature is 217℃, lower than 300℃, and when it is used as a CF sizing layer, it completely meets the forming temperature requirements of CF / PAEK composite materials.

[0072] Figure 4 The surface morphology diagram of T800 grade carbon fiber sized with the peptide amide acid aqueous emulsion sizing agent prepared in Example 1; from the figure, it can be seen that a clear sizing layer can be observed on the surface, and 1 wt% of the emulsion aqueous sizing agent can successfully size.

[0073] Although the above examples make a detailed description of the present application, it is only a part of the embodiments of the present application but not all the embodiments, and people can also obtain other embodiments according to the present embodiments without creativity, which all belong to the protection scope of the present application.

Claims

1. A peptide amic acid aqueous emulsion sizing agent, characterized in that, The raw materials for preparation, by mass parts, include: 1-2 parts of amyl acid containing monoamide groups, Solvent 2-10 parts, Lubricant 0.1~0.5 parts, Stabilizer 0.1~0.5 parts, Water 86.5~96.3 parts, Emulsifier 0.5~1.5 parts.

2. The peptide amyl acid aqueous emulsion sizing agent according to claim 1, characterized in that, The method for preparing the amic acid containing a monoamide group includes the following steps: In a protective gas atmosphere, an aromatic diamine, an aromatic monohydric anhydride, and a polar aprotic solvent are mixed and subjected to a condensation reaction to obtain an amide acid containing a monoamide group.

3. The peptide amyl acid aqueous emulsion sizing agent according to claim 2, characterized in that, The aromatic diamine is one or more of 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 2,4'-diaminodiphenyl ether, 4,4'-bis(3-aminophenoxy)benzophenone, 4,4'-bis(4-aminophenoxy)benzophenone, 3,4'-bis(4-aminophenoxy)benzophenone, 3,3'-bis(3-aminophenoxy)benzophenone, 3,3'-bis(4-aminophenoxy)benzophenone, p-phenylenediamine, and m-phenylenediamine.

4. The peptide amyl acid aqueous emulsion sizing agent according to claim 2, characterized in that, The aromatic monohydric anhydride is phthalic anhydride.

5. The peptide amic acid aqueous emulsion sizing agent according to claim 1, characterized in that, The lubricant is one or more of the following: polyoxyethylene ether, fatty acid polyoxyethylene ether, a mixture of polyoxyethylene and polyoxypropylene ether, butyl stearate, higher fatty amine, higher fatty alcohol, and higher fatty ester; the higher fatty amine, higher fatty alcohol, and higher fatty ester refer to organic compounds with ≥10 carbon atoms.

6. The peptide amic acid aqueous emulsion sizing agent according to claim 1, characterized in that, The stabilizer is one or more of ammonium chloride, ammonium sulfate, and ammonium nitrate.

7. The peptide amino acid aqueous emulsion sizing agent according to claim 1, characterized in that, The emulsifier is a surfactant; the surfactant includes one or more of the following: sodium dodecylbenzenesulfonate, sorbitan monostearate polyethylene ether, alkylphenol polyoxyethylene ether, castor oil polyethylene ether, fatty acid and ethylene oxide addition polymer, polyoxyethylene dehydrated sorbitan monooleate, polyoxyethylene dehydrated sorbitan trioleate, polyoxyethylene dehydrated sorbitan palmitate, polyoxyethylene dehydrated sorbitan monostearate, polyoxyethylene monolaurate, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, and polyoxyethylene fatty acid amino ether.

8. A method for preparing the peptiamide acid aqueous emulsion sizing agent according to any one of claims 1 to 7, characterized in that, Includes the following steps: An amic acid containing a monoamide group is mixed with a solvent to obtain an amic acid solution containing a monoamide group; The amic acid solution containing monoamide groups, lubricant, stabilizer, emulsifier and a portion of water are mixed, dispersed and emulsified, and then diluted with the remaining water to obtain the peptide amic acid aqueous emulsion sizing agent.

9. The application of the peptamidic acid aqueous emulsion sizing agent according to any one of claims 1 to 7 or the peptamidic acid aqueous emulsion sizing agent prepared by the preparation method according to claim 8 in carbon fiber sizing.

10. A method for sizing carbon fiber, characterized in that, Includes the following steps: After impregnating the sizing agent with the sizing agent, the carbon fiber is dried, thermally imidized and then wound up to complete the sizing process. The sizing agent is the peptamidic acid aqueous emulsion sizing agent according to any one of claims 1 to 7 or the peptamidic acid aqueous emulsion sizing agent prepared by the preparation method according to claim 8.

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