Water-based sizing agent based on photosensitive polyimide, preparation method of water-based sizing agent, sizing method of carbon fiber material and sized carbon fiber material

Abstract

The invention relates to the field of polyimide sizing agents, in particular to a water-based sizing agent based on photosensitive polyimide, a preparation method of the water-based sizing agent, a sizing method of a carbon fiber material and a sized carbon fiber material. The synthesis method of the polyesteramide component in the water-based sizing agent provided by the invention is simple and rapid, the structure is novel and diversified, and after the water-based sizing agent treats a carbon fiber material, the polyesteramide is subjected to thermal imidization to obtain polyimide with novel and diversified structures. The water-based sizing agent provided by the invention is good in water solubility, excellent in sizing amount when being used for treating carbon fibers and good in interface bonding performance with a carbon fiber material, and the obtained sized carbon fiber material is high in overall performance. Tests show that the sizing amount of the water-based sizing agent provided by the invention is greater than 0.8%.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of polyimide sizing agent, and particularly relates to a water-based sizing agent based on photosensitive polyimide, a preparation method of the water-based sizing agent, and a sizing method of carbon fiber material. BACKGROUND

[0002] Carbon fibers are widely used in aerospace, automobiles, sports equipment, military and other fields due to their high strength, high modulus, light weight, high temperature resistance, corrosion resistance and other characteristics. The comprehensive performance of carbon fibers makes them become the key materials that cannot be replaced in modern high-end manufacturing industry. Carbon fibers are brittle and have poor impact resistance, but the performance can be optimized through composite material design (such as being combined with resin or metal). A uniform and dense protective film is formed on the surface of carbon fibers by sizing agent, which can not only improve the bundling and wear resistance of carbon fiber tows, but also effectively reduce the fiber fuzzing phenomenon, thereby improving the performance of carbon fiber products. At the same time, sizing agent can form an interfacial layer of the composite material, increase the interfacial adhesion of the composite material, and improve the performance of the composite material.

[0003] Traditional carbon fiber sizing agents use epoxy resin and polyurethane as sizing agent sizing. They are mainly used for protecting fibers, improving processing performance and enhancing the interfacial bonding with resin matrix. Among them, the compatibility of epoxy resin is the best, and the flexibility of polyurethane is good. These sizing agents are mostly carried by organic solvents, and need to be dried and cured. The common problem is that the temperature resistance is insufficient (usually less than 200 DEG C), and degradation occurs at high processing temperature (> 300 DEG C) and high use temperature, which affects the interfacial adhesion of the composite material, thereby reducing the mechanical properties of the composite material at high temperature. In recent years, researchers have begun to focus on the development of sizing agents suitable for high-temperature resistant carbon fiber composites, and traditional sizing agents are gradually being replaced by high-performance new sizing agents such as polyimide.

[0004] Polyimide sizing agents mainly include solvent-based polyimide sizing agents: polyamide acid as precursor, dissolved in NMP or DMF organic solvent, high temperature resistance but poor environmental protection. Water-based polyimide sizing agent: realize water dispersion through polyamide acid salt or self-emulsifying technology, with environmental protection and high temperature resistance. Modified polyimide sizing agent: including silicon oil modification (improve wear resistance), nano composite (such as carbon nanotube reinforcement), fluorination modification (reduce surface energy), etc., optimize processing and interfacial performance. Composite polyimide sizing agent: such as polyimide / epoxy or polyimide / polyurethane mixed system, balance temperature resistance and flexibility.

[0005] Traditional polyimide resins are basically insoluble in water, and can only be dissolved in organic solvents such as dimethylacetamide and dimethylformamide to form an organic solvent type polyimide resin solution for use. At present, in order to realize the preparation of water-soluble polyimide, it is usually necessary to introduce water-soluble groups such as hydroxyl or carboxyl into the synthetic monomer to increase the water-solubility of the polyimide. However, the structural modification of the synthetic monomer has great limitations, and the types of commercial substrate monomers are less and relatively expensive. The above problems seriously limit the application of polyimide resins in water-based sizing agents.

[0006] In addition, although some water-soluble polyimide resins have been disclosed in the prior art, which are theoretically suitable for application in water-based sizing agents, there is currently no relevant guidance on which water-soluble polyimide resin can achieve high sizing amount and interfacial adhesion performance. SUMMARY

[0007] Therefore, the technical problem to be solved by the present application is to provide a water-based sizing agent based on photosensitive polyimide and a preparation method thereof, a sizing method of carbon fiber material, and sized carbon fiber material. The water-based sizing agent provided by the present application has good water solubility, high sizing amount for treating carbon fiber, good interfacial adhesion performance with carbon fiber material, and high overall performance of the obtained sized carbon fiber material.

[0008] The present application provides a water-based sizing agent, which comprises, by mass fraction:

[0009] Polyamide acid ester: 0.5 parts to 10 parts;

[0010] Surfactant: 0.1 parts to 5 parts;

[0011] Water: 100 parts to 300 parts;

[0012] The polyamide acid ester has a structure shown in Formula I:

[0013]

[0014] wherein n is 5 to 500;

[0015] X is selected from substituted or unsubstituted C 12 -C 30 aryl;

[0016] Ar1 is selected from substituted or unsubstituted C4-C 15 cycloalkyl or substituted or unsubstituted C6-C 30 aryl;

[0017] R is selected from substituted or unsubstituted C1-C 12 alkyl or substituted or unsubstituted C6-C 12 aryl;

[0018] Z is selected from substituted or unsubstituted alkyl of less than 12 carbons or substituted or unsubstituted C6-C10 aryl; 12

[0019] A is selected from Cl - , Br - , I - , ClO4 - , BrO4 - , IO4 - , NO3 - , BF4 - , PF4 - , MeSO3 - , or CF3SO3 - .

[0020] Preferably, the mass ratio of the polyamide acid ester, the surfactant and the water in the aqueous sizing agent provided by the present application is (2.5-3.5):(0.1-0.2):(180-270). More preferably, the aqueous sizing agent provided by the present application comprises: 2.5-3.5 parts of polyamide acid ester, 0.1-0.2 parts of lauric acid, and 200 parts of water; or, comprises: 2.5-3.5 parts of polyamide acid ester, 0.1-0.2 parts of polyether modified polysiloxane, and 250 parts of water; or, comprises: 2.5-3.5 parts of polyamide acid ester, 0.1-0.2 parts of ethoxylated lauric acid amine, and 200 parts of water.

[0021] The aqueous sizing agent provided by the present application does not contain organic solvents and does not contain other organic substances except for the polyamide acid ester and the surfactant. The surfactant in the aqueous sizing agent provided by the present application is also called a surface active leveling agent, which can reduce the surface tension of water, improve the surface wetting, leveling and defoaming of carbon fibers. Preferably, the surfactant in the present application is selected from one or more of sodium dodecyl sulfonate, sodium dodecyl sulfate, polyether modified polysiloxane, ethoxylated lauric acid amine, glycerol-stearate, polydimethylsiloxane, polyester modified organosiloxane, alkyl modified organosiloxane, polyether modified silicone oil, lauric acid, and palmityl trialkyl melamine.

[0022] The polyamide acid ester in the aqueous sizing agent provided by the present application is a polyamide acid ester containing a quaternary ammonium salt in the side chain, which has the structure shown in the aforementioned formula I. The polyamide acid ester in the present application has a side chain group of -Z-N(R)2·HA, wherein · represents an ionic bond between HA and -Z-N(R)2, and the group is derived from a fatty amine or an aromatic amine containing a hydroxyl group. In the group, R is selected from substituted or unsubstituted C1-C12 alkyl or substituted or unsubstituted C6-C10 aryl. 12 12 ​​alkyl of less than 12 carbons or a substituted or unsubstituted C6-C 12 alkyl of less than 12 carbons or a substituted or unsubstituted C6-C - , Br - , I - , CIO4 - , BrO4 - , IO4 - , NO3 - , BF4 - , PF4 - , MeSO3 - , or CF3SO3 - . Preferably, R is selected from a substituted or unsubstituted alkyl of less than 8 carbons or a substituted or unsubstituted C1-C8 aryl; more preferably, R is selected from a C1-C8 alkyl; still more preferably, R is selected from methyl or ethyl. Preferably, Z is selected from a substituted or unsubstituted alkyl of less than 12 carbons or a substituted or unsubstituted C6-C 12 aryl; more preferably, Z is selected from a substituted or unsubstituted alkyl of less than 6 carbons or a substituted or unsubstituted phenyl; still more preferably, Z is selected from methyl or ethyl. Preferably, A is selected from Cl - , Br - , I - , NO3 - , MeSO3 - , or CF3SO3 - ; still more preferably, A is selected from Cl - , Br - , or I - .

[0023] The polyamic acid esters of the present invention have an X group that is derived from a diamine necessary for the synthesis of a polyimide. Specifically, X is selected from a substituted or unsubstituted C 12 -C 30 aryl; preferably, X is selected from a group having a structure represented by Formula X-1 to Formula X-5;

[0024]

[0025] More preferably, X is selected from a group having a structure represented by Formula X-a to Formula X-h;

[0026]

[0027] The polyamic acid esters of the present invention also have an Ar1 group that is derived from a dianhydride necessary for the synthesis of a polyimide, which contains at least one aromatic or aliphatic ring structure. Specifically, Ar1 is selected from a substituted or unsubstituted C4-C 15 cycloalkyl or a substituted or unsubstituted C6-C30 Aryl group. Preferably, the Ar1 is selected from groups with structures shown in formulas Ar1-1 to Ar1-12;

[0028]

[0029] More preferably, the Ar1 is selected from groups with structures shown in formulas Ar1-a to Ar1-r;

[0030]

[0031] The polyamic acid ester described in this invention can be reacted using common, inexpensive, and readily available diamines, dianhydrides, and amino alcohols. It is not limited to monomers with intramolecular water-soluble groups such as hydroxyl and carboxyl groups. Ultimately, various novel, water-soluble polyimides with different structures can be obtained. This method has a wide range of applicable substrates, good economic efficiency, and a simple preparation process with low cost, meeting current environmental protection requirements. Specifically, it is prepared by the following steps:

[0032] A dianhydride having the structure of Formula 1 is reacted with an alcohol amine having the structure of Formula 2. The product of the reaction is then reacted with a diamine having the structure of Formula 3, and then acidified with protic acid HA to obtain a polyamic ester. (R)2N-Z—OH (Formula 2); H2N-X-NH2 (Formula 3).

[0033] This invention further includes activating the product obtained from the reaction before reacting it with a diamine having the structure of Formula 3. The activation described in this invention refers to a method for activating the carboxyl group to achieve the reaction between the carboxyl and amine groups. Specifically, the activation method of this invention involves adding an amide condensing agent formed by the carboxylic acid and amine groups. For example, the amide condensing agent is selected from carbodiimide, carbonyl diimidazole, carbium salt, or organophosphorus condensing agents; preferably, the amide condensing agent is selected from carbodiimide or carbonyl diimidazole condensing agents; more preferably, the amide condensing agent is selected from dicyclohexylcarbodiimide (DCC), diisopropylcarbodiimide (DIC), or 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDCI). Alternatively, the activation method of this invention uses a conventional acyl halide reagent to convert the carboxyl group into an acyl halide. The acyl halide reagent can be a thionyl halide, phosphoryl halide, or carbonyl halide, preferably a compound such as thionyl chloride (SOCl2), phosphorus oxychloride, or oxalyl chloride.

[0034] Specifically, the dianhydride having the structure of Formula 1 and the alcohol amine having the structure of Formula 2 are reacted at 0°C to 60°C for 5h to 7h under a protective gas atmosphere, then the reaction product and an acyl halide reagent, or the reaction product and an amide condensing agent are condensed at -5°C to 5°C for 3h to 7h, then the diamine having the structure of Formula 3 is added at -5°C to 5°C for 11h to 13h, and a protonic acid HA is added for acidification to obtain a polyamic acid ester.

[0035] More specifically, the dianhydride having the structure of Formula 1 and the alcohol amine having the structure of Formula 2 are reacted at 0°C to 60°C for 5h to 7h under a protective gas atmosphere, then the reaction product and SOCl2, or the reaction product and DCC are condensed at -5°C to 5°C for 3h to 7h, then the diamine having the structure of Formula 3 is added at -5°C to 5°C for 11h to 13h, and a protonic acid HA is added for acidification to obtain a polyamic acid ester.

[0036] In some embodiments of the present application, the dianhydride having the structure of Formula 1 is dissolved in an organic solvent under a protective gas atmosphere, the alcohol amine having the structure of Formula 2 is added to react at a temperature of 0°C to 60°C for 5h to 7h, then SOCl2 is added to the reaction product, or DCC is added to the reaction product to react at -5°C to 5°C for 3h to 7h, then the diamine having the structure of Formula 3 is continuously added to react at -5°C to 5°C for 11h to 13h, and a protonic acid HA is added for acidification to obtain a red aqueous polyamic acid ester solution, which can be precipitated by ethanol to obtain a light yellow aqueous polyamic acid ester solid powder.

[0037] The molar ratio of the dianhydride having the structure of Formula 1, the alcohol amine having the structure of Formula 2, the diamine having the structure of Formula 3 and the protonic acid HA in the present application is (0.8-1.2):(1.6-2.0):1:(2.0-3.0), for example 0.8:(1.6-2.0):1:(2.0-3.0), for example 0.9:(1.6-2.0):1, for example 1.0:(1.6-2.0):1:(2.0-3.0), for example 1.1:(1.6-2.0):1:(2.0-3.0), for example 1.2:(1.6-2.0):1:(2.0-3.0). The ratio of the amount of the amide condensing agent or the acyl halide reagent and the amount of the diamine having the structure of Formula 3 in the present application is (1.6-2.4):1. The protective gas in the present application is selected from one or more of nitrogen, helium, neon, argon. The organic solvent in the present application is selected from one or more of DMF, DMAc, NMP, butyrolactone.

[0038] The dianhydride having the structure of Formula 1 is a binary anhydride, which is a necessary component of a polymeric monomer of polyamide acid ester, and is specifically selected from at least one of 1,2,4,5-cyclohexane tetracarboxylic dianhydride, 1,2,3,4-cyclobutane tetracarboxylic dianhydride, 1,2,4,5-benzene tetracarboxylic dianhydride, 3,4,3',4'-biphenyl tetracarboxylic dianhydride, 2,3,3',4'-biphenyl tetracarboxylic dianhydride, 2,3,2',3'-biphenyl tetracarboxylic dianhydride, 3,4,3',4'-benzophenone tetracarboxylic dianhydride, 2,3,3',4'-benzophenone tetracarboxylic dianhydride, 3,4,3',4'-diphenyl ether tetracarboxylic dianhydride, 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride, 3,4,3',4'-diphenyl sulfone tetracarboxylic dianhydride, 2,3,3',4'-diphenyl sulfone tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)phenyl dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)phenyl dianhydride, 3,4-dicarboxybenzoic acid-(3,4-dicarboxyphenol) ester dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, and 4,4'-oxybisphthalic anhydride. Preferably, the dianhydride having the structure of Formula 1 is selected from pyromellitic dianhydride, 3,4,3',4'-biphenyl tetracarboxylic dianhydride, 2,3,3',4'-biphenyl tetracarboxylic dianhydride, 2,3,2',3'-biphenyl tetracarboxylic dianhydride, 3,4,3',4'-diphenyl ether tetracarboxylic dianhydride, or 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride. More preferably, the dianhydride having the structure of Formula 1 is selected from 3,4,3',4'-diphenyl ether tetracarboxylic dianhydride or 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride.

[0039] The alcohol amine having the structure of Formula 2 is a necessary component of an alcohol amine monomer in an esterification process. Preferably, the alcohol amine having the structure of Formula 2 is selected from at least one of dimethylaminoethanol, dimethylaminopropanol, dimethylaminopentanol, diethylaminopentanol, 4-dimethylaminophenol, and 2-diphenylaminoethanol; more preferably, the alcohol amine having the structure of Formula 2 is selected from at least one of dimethylaminoethanol, dimethylaminopropanol, dimethylaminopentanol, and diethylaminopentanol.

[0040] The diamine having the structure of Formula 3, as an essential component of the polymeric monomer of the polyamic acid ester, is selected from a diamine containing a diphenyl ether group structure or a diamine containing a diphenyl sulfone group structure, and is particularly selected from at least one of 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-diaminodiphenyl sulfone, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 1,3-bis(4-aminophenoxy)biphenyl, or 4,4'-bis(3-aminophenoxy)biphenyl. Preferably, the selected diamine having the structure of Formula 3 is selected from 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, or 4,4'-diaminodiphenyl ether. More preferably, the diamine having the structure of Formula 3 is selected from 3,4'-diaminodiphenyl ether or 4,4'-diaminodiphenyl ether.

[0041] The protonic acid HA is selected from HCl, HBr, HI, HClO4, HBrO4, HIO4, HNO3, HBF4, HPF4, MeSO3H, or CF3SO3H. More preferably, the protonic acid HA is selected from HCl, HBr, HI, HNO3, MeSO3H, or CF3SO3H. Even more preferably, the protonic acid HA is selected from HCl, HBr, or HI.

[0042] The present application also provides a preparation method of the aqueous sizing agent described above, comprising the following steps:

[0043] The polyamic acid ester, water, and surfactant are mixed at a temperature of 20-40°C to obtain the aqueous sizing agent. Specifically, the water and surfactant are added to the polyamic acid ester while stirring to obtain the aqueous sizing agent; the water is added at a speed of 2.5-3.5 g / min. Preferably, the water is added at a speed of 2 g / min.

[0044] The aqueous sizing agent provided by the present application can be attached to the surface of the carbon fiber through the immersion sizing process, and is subjected to a heating process at 200-400°C, wherein the component polyamic ester is subjected to thermal imidization to obtain polyimide, which is solidified on the surface of the carbon fiber. The polyimide obtained by the present application has the structure of Formula II.

[0045]

[0046] wherein Ar1, X, and n are the same as described above, and are not repeated.

[0047] The present application also provides a sizing method of a carbon fiber material, comprising the following steps:

[0048] The carbon fiber material is sized in a dilute solution of the sizing agent, and then is heat treated at 200-400 DEG C; the sizing agent is selected from the sizing agent according to any of the preceding technical solutions or the sizing agent prepared according to any of the preceding technical solutions.

[0049] Specifically, the carbon fiber material is sized by being immersed in the sizing agent, is taken out after sizing is completed, and then is heat treated at 200-400 DEG C, and finally is dried. Preferably, the sizing time is 80-100 s. Preferably, the mass fraction of the dilute solution of the sizing agent is 2-5%.

[0050] The application also provides a sized carbon fiber material, which is obtained by treating a carbon fiber material with the sizing agent according to any of the preceding technical solutions or the sizing agent prepared according to any of the preceding technical solutions.

[0051] The application provides a photosensitive polyimide-based aqueous sizing agent, a preparation method thereof, a sizing method for carbon fiber material, and sized carbon fiber material. The polyamide ester in the aqueous sizing agent has a simple and fast synthesis method, a novel and diverse structure, and after the aqueous sizing agent is used to treat the carbon fiber material, the polyamide ester is heat imidized to obtain a polyimide with a novel and diverse structure. The aqueous sizing agent has good water solubility, excellent sizing amount for treating the carbon fiber material, good interfacial adhesion to the carbon fiber material, and high overall performance of the sized carbon fiber material. Tests show that the sizing amount of the aqueous sizing agent is greater than 0.8. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 A preparation flowchart of the polyamide acid ester according to the application;

[0053] Figure 2 A flowchart of heat imidization of the polyamide acid ester according to the application to become a polyimide. DETAILED DESCRIPTION

[0054] The application discloses a photosensitive polyimide-based aqueous sizing agent, a preparation method thereof, a sizing method for carbon fiber material, and sized carbon fiber material. Those skilled in the art can refer to the content herein, and appropriately improve process parameters to realize. It is particularly pointed out that all similar replacements and changes are obvious to those skilled in the art, and are regarded as being included in the application. The method and application of the application have been described by using preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application herein without departing from the content, spirit and scope of the application, to realize and apply the technology of the application.

[0055] The present application first prepares a polyamide acid ester, and then performs sizing agent configuration, such as Figure 1 Figure 1 is a preparation flow chart of the polyamide acid ester described in the present application.

[0056] The present application is further described below in conjunction with examples:

[0057] Example 1

[0058] Into a reaction vessel, 4,4'-oxydiphthalic anhydride ODPA (161.1 mmol, 50.0 g), DMF (184 g), pyridine (322.2 mmol, 25.5 g), dimethylaminoethanol (322.2 mmol, 28.7 g) were sequentially added, and stirred at 0°C for 6 h. Into the bottle, thionyl chloride SOCl2 (322.2 mmol, 38.0 g) was added, and stirred at 0°C for 3 h, 4,4'-oxydianiline ODA (161.1 mmol, 32.2 g) was added, and stirred at 0°C for 12 h, and saturated HCl solution (322.2 mmol, 22.9 mL) was added. The obtained polyamide acid ester solution was precipitated with ethanol to obtain a yellow polyamide acid ester powder.

[0059] Sizing agent configuration: 3 g of the polyamide ester powder was weighed, and deionized water was added dropwise while stirring at a temperature of 30°C, the stirring speed was 200 r / min, and the mass of water added to the mixture per minute was 3 g. During the addition of water, 0.15 g of lauric acid was simultaneously added. When 200 g of water was added, a transparent, uniform and stable water-soluble polyimide resin solution with a solid content of 1.5 wt% was obtained, which was a polyimide sizing agent and was subjected to sizing test experiment.

[0060] Example 2

[0061] Into a reaction vessel, 4,4'-oxydiphthalic anhydride ODPA (161.1 mmol, 50.0 g), DMF (184 g), pyridine (322.2 mmol, 25.5 g), dimethylaminoethanol (322.2 mmol, 28.7 g) were sequentially added, and stirred at 0°C for 6 h. Into the bottle, thionyl chloride SOCl2 (322.2 mmol, 38.0 g) was added, and stirred at 0°C for 3 h, 4,4'-oxydianiline ODA (161.1 mmol, 32.2 g) was added, and stirred at 0°C for 12 h, and saturated HCl solution (322.2 mmol, 22.9 mL) was added. The obtained polyamide acid ester solution was precipitated with ethanol to obtain a yellow polyamide acid ester powder.

[0062] ​Sizing agent preparation: 3 g of polyamide ester powder was weighed, and deionized water was added dropwise while stirring at a temperature of 30°C. The stirring speed was 200 r / min, and the mass of water added to the mixture per minute was 3 g. During the addition of water, 0.15 g of polyether-modified polysiloxane was added simultaneously. After 200 g of water was added, a transparent, uniform, and stable water-soluble polyimide resin solution with a solid content of 1.5 wt% was obtained, which was the polyimide sizing agent and was used for sizing test experiments.

[0063] Example 3

[0064] Into the reaction vessel, 3,3',4,4'-benzophenonetetracarboxylic dianhydride BTDA (161.1 mmol, 51.9 g), DMF (184 g), pyridine (322.2 mmol, 25.5 g), dimethylaminoethanol (322.2 mmol, 28.7 g) were added in sequence, and stirring was performed at 0°C for 6 h. Into the bottle, thionyl chloride SOCl2 (322.2 mmol, 38.0 g) was added, stirring was performed at 0°C for 3 h, 4,4'-oxydianiline ODA (161.1 mmol, 32.2 g) was added, stirring was performed at 0°C for 12 h, and HI (322.2 mmol, 41.2 g) was added. The obtained polyamide acid ester solution was precipitated with ethanol to obtain a light yellow polyamide acid ester powder.

[0065] Sizing agent preparation: 3 g of polyamide ester powder was weighed, and deionized water was added dropwise while stirring at a temperature of 30°C. The stirring speed was 200 r / min, and the mass of water added to the mixture per minute was 3 g. During the addition of water, 0.15 g of polyether-modified polysiloxane was added simultaneously. After 200 g of water was added, a transparent, uniform, and stable water-soluble polyimide resin solution with a solid content of 1.5 wt% was obtained, which was the polyimide sizing agent and was used for sizing test experiments.

[0066] Example 4

[0067] Into the reaction vessel, 4,4'-oxydiphthalic anhydride ODPA (161.1 mmol, 50.0 g), DMF (184 g), pyridine (322.2 mmol, 25.5 g), dimethylaminoethanol (322.2 mmol, 28.7 g) were added in sequence, and stirring was performed at 0°C for 6 h. Into the bottle, DCC (322.2 mmol, 66.5 g) was added, stirring was performed at 0°C for 3 h, 4,4'-diaminodiphenyl sulfone DDS (161.1 mmol, 40.0 g) was added, stirring was performed at 0°C for 12 h, and HI (322.2 mmol, 41.2 g) was added. The obtained polyamide acid ester solution was precipitated with ethanol to obtain a yellow polyamide acid ester powder.

[0068] Sizing agent preparation: 3 g of polyamide ester powder was weighed, and deionized water was added dropwise while stirring at 30 °C, with a stirring speed of 200 r / min, and the mass of water added per minute in the mixture was 3 g. During the addition of water, 0.15 g of polyether-modified polysiloxane was added simultaneously. After 200 g of water was added, a transparent, uniform, and stable water-soluble polyimide resin solution with a solid content of 1.5 wt% was obtained, which was the polyimide sizing agent and was used for sizing test experiments.

[0069] Example 5

[0070] Into the reaction vessel, 4,4'-oxydiphthalic anhydride ODPA (161.1 mmol, 50.0 g), DMF (184 g), pyridine (322.2 mmol, 25.5 g), dimethylaminoethanol (322.2 mmol, 28.7 g) were sequentially added, and stirring was performed at 0 °C for 6 h. Into the bottle, thionyl chloride SOCl2 (322.2 mmol, 38.0 g) was added, stirring was performed at 0 °C for 3 h, 1,4-cyclohexanediamine CHDA (161.1 mmol, 18.4 g) was added, stirring was performed at 0 °C for 12 h, and HClO4 (322.2 mmol, 32.4 g) was added. The obtained polyamide acid ester solution was precipitated with ethanol to obtain a yellow polyamide acid ester powder.

[0071] Sizing agent preparation: 3 g of polyamide ester powder was weighed, and deionized water was added dropwise while stirring at 30 °C, with a stirring speed of 200 r / min, and the mass of water added per minute in the mixture was 3 g. During the addition of water, 0.15 g of polyether-modified polysiloxane was added simultaneously. After 200 g of water was added, a transparent, uniform, and stable water-soluble polyimide resin solution with a solid content of 1.5 wt% was obtained, which was the polyimide sizing agent and was used for sizing test experiments.

[0072] Example 6

[0073] Into the reaction vessel, 4,4'-oxydiphthalic anhydride ODPA (161.1 mmol, 50.0 g), DMF (184 g), pyridine (322.2 mmol, 25.5 g), dimethylaminoethanol (322.2 mmol, 28.7 g) were sequentially added, and stirring was performed at 0 °C for 6 h. Into the bottle, thionyl chloride SOCl2 (322.2 mmol, 38.0 g) was added, stirring was performed at 0 °C for 3 h, 1,4-cyclohexanediamine CHDA (161.1 mmol, 18.4 g) was added, stirring was performed at 0 °C for 12 h, and HClO4 (322.2 mmol, 32.4 g) was added. The obtained polyamide acid ester solution was precipitated with ethanol to obtain a yellow polyamide acid ester powder.

[0074] Sizing agent preparation: 3 g of polyamide ester powder was weighed, and deionized water was added dropwise while stirring at 30 °C, with a stirring speed of 200 r / min, and the mass of water added per minute in the mixture was 3 g. During the addition of water, 0.15 g of polyether-modified polysiloxane was added simultaneously. After 200 g of water was added, a transparent, uniform, and stable water-soluble polyimide resin solution with a solid content of 1.5 wt% was obtained, which was the polyimide sizing agent and was used for sizing test experiments.

[0075] Example 7

[0076] Into the reaction vessel, 4,4'-oxydiphthalic anhydride ODPA (161.1 mmol, 50.0 g), DMF (184 g), pyridine (322.2 mmol, 25.5 g), dimethylaminopentanol (322.2 mmol, 41.2 g) were added in sequence, and stirring was performed at 0 °C for 6 h. Into the bottle, thionyl chloride SOCl2 (322.2 mmol, 38.0 g) was added, stirring was performed at 0 °C for 3 h, 4,4'-oxydianiline ODA (161.1 mmol, 32.2 g) was added, stirring was performed at 0 °C for 12 h, and HBF4 (322.2 mmol, 28.3 g) was added. The obtained polyamide acid ester solution was precipitated with ethanol to obtain yellow polyamide acid ester powder.

[0077] Sizing agent preparation: 3 g of polyamide ester powder was weighed, and deionized water was added dropwise while stirring at 30 °C, with a stirring speed of 200 r / min, and the mass of water added per minute in the mixture was 3 g. During the addition of water, 0.15 g of polyether-modified polysiloxane was added simultaneously. After 200 g of water was added, a transparent, uniform, and stable water-soluble polyimide resin solution with a solid content of 1.5 wt% was obtained, which was the polyimide sizing agent and was used for sizing test experiments.

[0078] Example 8

[0079] Into the reaction vessel, 4,4'-oxydiphthalic anhydride ODPA (161.1 mmol, 50.0 g), DMF (184 g), pyridine (322.2 mmol, 25.5 g), dimethylaminopentanol (322.2 mmol, 41.2 g) were added in sequence, and stirring was performed at 0 °C for 6 h. Into the bottle, thionyl chloride SOCl2 (322.2 mmol, 38.0 g) was added, stirring was performed at 0 °C for 3 h, 4,4'-oxydianiline ODA (161.1 mmol, 32.2 g) was added, stirring was performed at 0 °C for 12 h, and HBF4 (322.2 mmol, 28.3 g) was added. The obtained polyamide acid ester solution was precipitated with ethanol to obtain yellow polyamide acid ester powder.

[0080] Sizing agent preparation: 3 g of polyamide ester powder was weighed, and deionized water was added dropwise while stirring at a temperature of 30°C, with a stirring speed of 200 r / min, and the mass of water added to the mixture per minute was 3 g. During the addition of water, 0.15 g of polyether-modified polysiloxane was added simultaneously. After 200 g of water was added, a transparent, uniform, and stable water-soluble polyimide resin solution with a solid content of 1.5 wt% was obtained, which was used as a polyimide sizing agent and subjected to a sizing test.

[0081] Comparative Example 1

[0082] To the reaction vessel, 4,4'-oxydiphthalic anhydride ODPA (161.1 mol, 50.0 g), DMF (184 g), pyridine (322.2 mmol, 25.5 g), and 4-diphenylaminophenol (322.2 mol, 84.0 g) were sequentially added, and the mixture was stirred at 0°C for 6 h. To the bottle, dicyclohexyl carbodiimide DCC (322.2 mmol, 66.4 g) and 4,4'-diaminodiphenyl ether ODA (161.1 mmol, 32.2 g) were added, and the mixture was stirred at 0°C for 12 h. Saturated HCl solution (322.2 mmol, 22.9 mL) was added, and the obtained polyamide ester solution was precipitated with ethanol to obtain a yellow polyamide ester powder.

[0083] Sizing agent preparation: 3 g of polyamide ester powder was weighed, and deionized water was added dropwise while stirring at a temperature of 30°C, with a stirring speed of 200 r / min, and the mass of water added to the mixture per minute was 3 g. During the addition of water, 0.15 g of polyether-modified polysiloxane was added simultaneously. After 200 g of water was added, a transparent, uniform, and stable water-soluble polyimide resin solution with a solid content of 1.5 wt% was obtained, which was used as a polyimide sizing agent and subjected to a sizing test.

[0084] Comparative Example 2

[0085] To the reaction vessel, 4,4'-oxydiphthalic anhydride ODPA (161.1 mol, 50.0 g), DMF (184 g), pyridine (322.2 mmol, 25.5 g), and 4-diphenylaminophenol (322.2 mol, 84.0 g) were sequentially added, and the mixture was stirred at 0°C for 6 h. To the bottle, dicyclohexyl carbodiimide DCC (322.2 mmol, 66.4 g) and 4,4'-diaminodiphenyl ether ODA (161.1 mmol, 32.2 g) were added, and the mixture was stirred at 0°C for 12 h. Saturated HCl solution (322.2 mmol, 22.9 mL) was added, and the obtained polyamide ester solution was precipitated with ethanol to obtain a yellow polyamide ester powder.

[0086] Sizing agent preparation: 3 g of polyamide ester powder was weighed, and deionized water was added dropwise while stirring at 30°C, at a stirring speed of 200 r / min, and at a water addition rate of 3 g / min. During the water addition, 0.15 g of polyether-modified polysiloxane was added. After the water addition, a transparent, uniform, and stable water-soluble polyimide resin solution was not obtained.

[0087] Comparative Example 3

[0088] To the reaction vessel were sequentially added 4,4'-oxydiphthalic anhydride ODPA (161.1 mol, 50.0 g), DMF (184 g), pyridine (322.2 mmol, 25.5 g), diethanolamine (322.2 mol, 33.8 g), and stirring was performed at 0°C for 6 h. To the bottle were sequentially added dicyclohexyl carbodiimide DCC (322.2 mmol, 66.4 g), 4,4'-oxydianiline ODA (161.1 mmol, 32.2 g), and stirring was performed at 0°C for 12 h. Saturated HCl solution (322.2 mmol, 22.9 mL) was added, and the resulting polyamide acid ester solution was precipitated with ethanol to obtain a yellow polyamide acid ester powder.

[0089] Sizing agent preparation: 3 g of polyamide ester powder was weighed, and deionized water was added dropwise while stirring at 30°C, at a stirring speed of 200 r / min, and at a water addition rate of 3 g / min. During the water addition, 0.15 g of polyether-modified polysiloxane was added. After the water addition, a transparent, uniform, and stable water-soluble polyimide resin solution was not obtained.

[0090] Comparative Example 4

[0091] To the reaction vessel were sequentially added 4,4'-oxydiphthalic anhydride ODPA (161.1 mol, 50.0 g), DMF (184 g), pyridine (322.2 mmol, 25.5 g), triethanolamine (322.2 mol, 48.0 g), and stirring was performed at 0°C for 6 h. To the bottle were sequentially added dicyclohexyl carbodiimide DCC (322.2 mmol, 66.4 g), 4,4'-oxydianiline ODA (161.1 mmol, 32.2 g), and stirring was performed at 0°C for 12 h. Saturated HCl solution (322.2 mmol, 22.9 mL) was added, and the resulting polyamide acid ester solution was precipitated with ethanol to obtain a yellow polyamide acid ester powder.

[0092] Sizing agent configuration: 3 g of polyamide ester powder was weighed, and deionized water was added dropwise while stirring at a temperature of 30°C, with a stirring speed of 200 r / min, and the mass of water added per minute in the mixed solution was 3 g. During the addition of water, 0.15 g of polyether-modified polysiloxane was simultaneously added. After the addition of water, a transparent, uniform, and stable water-soluble polyimide resin solution could not be obtained.

[0093] Comparative Example 5

[0094] Into a reaction vessel, 4,4'-oxydiphthalic anhydride ODPA (161.1 mol, 50.0 g), DMF (184 g), pyridine (322.2 mmol, 25.5 g), and ethanolamine (322.2 mol, 19.6 g) were sequentially added, and stirring was performed at 0°C for 6 h. Into the bottle, dicyclohexyl carbodiimide DCC (322.2 mmol, 66.4 g), and 4,4'-diamino diphenyl ether ODA (161.1 mmol, 32.2 g) were added, and stirring was performed at 0°C for 12 h. Saturated HCl solution (322.2 mmol, 22.9 mL) was added, and the obtained polyamide acid ester solution was precipitated with ethanol, but yellow polyamide acid ester powder could not be obtained.

[0095] Comparative Example 6

[0096] Into a reaction vessel, 4,4'-oxydiphthalic anhydride ODPA (161.1 mol, 50.0 g), DMF (184 g), pyridine (322.2 mmol, 25.5 g), and N-methyl-2-hydroxyethylamine (322.2 mol, 24.2 g) were sequentially added, and stirring was performed at 0°C for 6 h. Into the bottle, dicyclohexyl carbodiimide DCC (322.2 mmol, 66.4 g), and 4,4'-diamino diphenyl ether ODA (161.1 mmol, 32.2 g) were added, and stirring was performed at 0°C for 12 h. Saturated HCl solution (322.2 mmol, 22.9 mL) was added, and the obtained polyamide acid ester solution was precipitated with ethanol, but yellow polyamide acid ester powder could not be obtained.

[0097] Comparative Example 7

[0098] Into a reaction vessel, pyromellitic dianhydride PMDA (161.1 mmol, 35.1 g), and 4,4'-diamino diphenyl ether ODA (161.1 mmol, 32.2 g) were sequentially added, and stirring was performed at 0°C for 6 h. Into the bottle, triethylamine (322.2 mmol, 16.3 g) was added, and stirring was performed at room temperature for 3 h. The obtained polyamide acid salt solution was precipitated with ethanol, and yellow polyamide acid salt powder was obtained.

[0099] Sizing agent preparation: 3 g of polyamide salt powder was weighed and deionized water was added dropwise while stirring at 30 °C. The stirring speed was 200 r / min, and 3 g of water was added to the mixture per minute. At the same time, 0.15 g of polyether-modified polysiloxane was added during the water addition process. After adding 200 g of water, a transparent, uniform, and stable water-soluble polyimide resin solution with a solid content of 1.5 wt% was obtained, which was the polyimide sizing agent and was used for sizing test experiments.

[0100] Comparative Example 8

[0101] Into the reaction vessel, 4,4'-oxydiphthalic anhydride ODPA (161.1 mmol, 50.0 g), DMF (184 g), pyridine (322.2 mmol, 25.5 g), 4-dimethylaminophenol (322.2 mmol, 44.2 g) were sequentially added, and the reaction was stirred at 0 °C for 6 h. Into the bottle, dichlorosulfoxide SOCl2 (322.2 mmol, 38.0 g) was added, and the reaction was stirred at 0 °C for 3 h. Then, 4,4'-oxydianiline ODA (161.1 mmol, 32.2 g) was added, and the reaction was stirred at 0 °C for 12 h. Finally, saturated HCl solution (322.2 mmol, 22.9 mL) was added, and the obtained polyamide acid ester solution was precipitated with ethanol to obtain a yellow polyamide acid ester powder.

[0102] Sizing agent preparation: 3 g of polyamide ester powder was weighed and deionized water was added dropwise while stirring at 30 °C. The stirring speed was 200 r / min, and 3 g of water was added to the mixture per minute. At the same time, 0.15 g of lauric acid was added during the water addition process. After adding 200 g of water, a transparent, uniform, and stable water-soluble polyimide resin solution with a solid content of 1.5 wt% was obtained, which was the polyimide sizing agent and was used for sizing test experiments.

[0103] Performance test:

[0104] (1) Solubility test: Water was added to the prepared polyamide acid ester of the examples and comparative examples, and deionized water was added dropwise while stirring at 30 °C. The stirring speed was 200 r / min, and 3 g of water was added to the mixture per minute. If complete dissolution occurred within 0.2 h, it was extremely soluble; if complete dissolution occurred within 0.5 h, it was soluble; if complete dissolution occurred within 1 h, it was soluble; and if no dissolution occurred within 1 h or if precipitates or gelation occurred, it was insoluble.

[0105] (2) Sizing test experiment: Carbon fiber yarn without sizing agent on the surface was immersed in the sizing agent (diluted to a mass fraction of 3%), and the sizing time was 90 s. After taking out, the oven temperature was 300 °C, and the drying time was 5 min. During this process, the polyamide acid ester in the sizing agent was thermally imidized to become polyimide, as shown in the following equation: Figure 2 ​Figure 2 Flow chart for thermal imidization of polyamic acid ester to polyimide.

[0106] Carbon fiber sizing amount: using the property that sizing agent can be dissolved in acetone, the sizing agent on the surface of carbon fiber was extracted by extraction reflux method, the fiber before desizing (W i ) after desizing (W f ) mass difference to calculate the sizing agent content. The sizing amount was calculated according to the following formula:

[0107]

[0108] (3) Interfacial shear strength (IFSS): solidifying resin droplets on single fiber, measuring debonding force, and calculating interfacial shear strength.

[0109] The results are shown in Table 1:

[0110] Table 1

[0111]

[0112] According to the data in Table 1, it can be seen from Examples 1-8 that whether the dianhydride and diamine are electron-rich or electron-deficient aromatic compounds or aliphatic compounds, water-soluble polyamic acid ester can be obtained by using the method, and the mechanical properties of the polyimide obtained by thermal imidization are not lost, and the sizing amount is greater than 0.85%. The polyamic acid ester powders obtained in Comparative Examples 1-4 have poor solubility, and good water-soluble polyamic acid ester cannot be obtained, and the interfacial shear strength of the polyimide obtained after thermal imidization is reduced. It may be because the macromolecular amino alcohol salt removed after imidization is difficult to volatilize. It can be seen from Comparative Examples 5-6 that when primary amine or secondary amine is used, the corresponding water-soluble polyamic acid ester cannot be obtained, which may be due to the competitive reaction caused by the amine group, which makes the polymerization unable to proceed normally.

[0113] The above description is only the preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can make equivalent replacements or changes to the technical solutions and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. An aqueous sizing agent, characterized in that, By mass parts, comprising: Polyamide acid ester: 0.5 parts to 10 parts; Surfactant: 0.1 parts to 5 parts; Water: 100 parts to 300 parts; The polyamide acid ester has a structure shown in formula I: Wherein, the n is 5 to 500; said X is selected from substituted or unsubstituted C 12 ~C 30 aryl; said Ar1is selected from substituted or unsubstituted C4to C 15 cycloalkyl or substituted or unsubstituted C6to C 30 aryl; R is selected from substituted or unsubstituted C1-C6alkyl or substituted or unsubstituted C6-C10aryl; 12 R is selected from substituted or unsubstituted C1-C6alkyl or substituted or unsubstituted C6-C10aryl; 12 R is selected from substituted or unsubstituted C1-C6alkyl or substituted or unsubstituted C6-C10aryl; Z is selected from substituted or unsubstituted alkyl of less than 12 carbons or substituted or unsubstituted C6to C12aryl; 12 ; and said A is selected from the group consisting of Cl - , Br - , I - , ClO4 - , BrO4 - , IO4 - , NO3 - , BF4 - , PF4 - , MeSO3 - or CF3SO3 - .

2. The aqueous sizing agent according to claim 1, characterized in that, The mass ratio of the polyamide acid ester, surfactant and water is (2.5-3.5):(0.1-0.2):(180-270).

3. The aqueous sizing agent according to claim 1, characterized in that, Comprising: Polyamide acid ester: 2.5 parts to 3.5 parts; Laurylic acid: 0.1 parts to 0.2 parts; Water: 200 parts; Or, comprising: Polyamide acid ester: 2.5 parts to 3.5 parts; Polyether modified polysiloxane: 0.1 parts to 0.2 parts; Water: 250 parts; Or, comprising: Polyamide acid ester: 2.5 parts to 3.5 parts; Ethoxylated lauric acid amine: 0.1 parts to 0.2 parts; Water: 200 parts.

4. The aqueous sizing agent according to claim 1, characterized in that, The surfactant is selected from one or more of sodium dodecyl sulfonate, sodium dodecyl sulfate, polyether modified polysiloxane, ethoxylated lauric acid amine, glycerol-stearate, dimethicone, polyester modified organosiloxane, alkyl modified organosiloxane, polyether modified silicone oil, lauric acid, and palmitic acid trialkyl melamine.

5. The aqueous sizing agent according to any one of claims 1 to 4, characterized in that, The R is selected from substituted or unsubstituted alkyl of less than 8 carbons or substituted or unsubstituted C1-C8 aryl; Z is selected from substituted or unsubstituted lower alkyl of less than 12 carbons or substituted or unsubstituted C6to Cι2aryl; 12 unsubstituted C6to Cι2aryl; The X is selected from a group of structures shown in formula X-1 to formula X-5; The Ar1 is selected from a group of structures shown in formula Ar1-1 to formula Ar1-12; 6. The aqueous sizing agent according to claim 1, characterized in that, The polyamide acid ester is prepared by the following steps: Reacting a dianhydride having a structure of formula 1 with an alcohol amine having a structure of formula 2, then reacting the resulting product with a diamine having a structure of formula 3, and adding a protonic acid HA to acidify, to obtain the polyamide acid ester; (R)2N-Z—OH Formula 2; H2N-XNH2 Formula 3.

7. A process for the preparation of an aqueous sizing agent as claimed in any one of claims 1 to 6, characterized in that Comprising the following steps: Mixing the polyamide acid ester, water and surfactant at a temperature of 20-40℃ to obtain the aqueous sizing agent.

8. A method of sizing a carbon fiber material, characterized by, Comprising the following steps: Sizing the carbon fiber material in a dilute solution of the sizing agent, and then heat treating at 200-400℃; The sizing agent is selected from the aqueous sizing agent of any one of claims 1-6 or the aqueous sizing agent obtained by the preparation method of claim 7.

9. The sizing method according to claim 8, characterized by, The mass fraction of the dilute solution of the sizing agent is 2-5%.

10. A sized carbon fiber material characterized in that, It is obtained by treating the carbon fiber material with the aqueous sizing agent of any one of claims 1-6 or the aqueous sizing agent obtained by the preparation method of claim 7.

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