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] In some applications (for example, the microelectronics industry) polyimide resins must be used in liquid form, but the polyimide resins currently under study are basically insoluble in water and can only be dissolved in organic solvents such as dimethylacetamide and dimethylformamide to form organic solvent-based polyimide resin solutions for use. Organic solvents are flammable, explosive, toxic, pollute the environment and are harmful to human health, causing many inconveniences in the storage, transportation and application of organic solvent-based polyimide resin solutions. In addition, some water-based sizing agents require the use of a large amount of organic solvent during preparation, which not only increases production costs but also may pollute the environment.

[0006] In addition, water-based sizing agents mainly use water as a solvent and add various functional components, so water-based sizing agents are favored due to their environmental protection, easy operation and other characteristics. However, existing water-based sizing agents still have some deficiencies. For example, some water-based sizing agents are prone to degradation at high temperatures, resulting in a decrease in the performance of the protective film and affecting the interfacial adhesion and overall performance of the composite material.

[0007] 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 a high sizing amount and interfacial adhesion performance. SUMMARY

[0008] Therefore, the technical problem to be solved by the present application is to provide a water-based sizing agent based on a photosensitive polyimide, a preparation method thereof, a sizing method of a carbon fiber material and a sized carbon fiber material. The water-based sizing agent provided by the present application has good water solubility, a high sizing amount for treating carbon fibers, good interfacial adhesion performance with the carbon fiber material and high overall performance of the sized carbon fiber material.

[0009] The present application provides a water-based sizing agent, which comprises, by mass fraction:

[0010] polyamide acid ester: 0.5 parts to 10 parts;

[0011] surfactant: 0.1 parts to 5 parts;

[0012] water: 100 parts to 300 parts;

[0013] The polyamide acid ester has a structure shown in Formula I:

[0014]

[0015] wherein n is 5 to 500;

[0016] X is selected from substituted or unsubstituted C6-C 30 aryl;

[0017] Ar1 is selected from substituted or unsubstituted C4-C6 cycloalkyl or substituted or unsubstituted C6-C10 aryl; 30 aryl;

[0018] R' and R" are independently selected from substituted or unsubstituted alkyl having less than 15 carbon atoms or substituted or unsubstituted aryl having less than 15 carbon atoms;

[0019] y is an integer from 1 to 6.

[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: polyamide acid ester: 2.5-3.5 parts; polyether modified polysiloxane: 0.1-0.2 parts; water: 200 parts; or, comprises: polyamide acid ester: 2.5-3.5 parts; sodium dodecyl sulfonate: 0.1-0.2 parts; water: 250 parts; or, comprises: polyamide acid ester: 2.5-3.5 parts; polyether modified dimethyl polysiloxane: 0.1-0.2 parts; water: 200 parts; or, comprises: polyamide acid ester: 2.5-3.5 parts; polysiloxane: 0.1-0.2 parts; water: 200 parts; or, comprises: polyamide acid ester: 2.5-3.5 parts; lauric acid: 0.1-0.2 parts; water: 200 parts.

[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, dimethyl polysiloxane, 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 side chain tertiary amine structure, which has the structure shown in the aforementioned formula I. The polyamide acid ester in the present application has a -(CH2) y -NR'R" side chain group derived from a tertiary amine containing a hydroxyl group. Wherein, R' and R" are independently selected from substituted or unsubstituted alkyl having less than 15 carbon atoms, substituted or unsubstituted heteroalkyl having less than 15 carbon atoms, substituted or unsubstituted aryl having less than 15 carbon atoms, or substituted or unsubstituted heteroaryl having less than 15 carbon atoms. Preferably, R' and R" are independently selected from C1-C15 alkyl, C1-C15 heteroalkyl, C6-C15 aryl or C6-C15 heteroaryl. 12The alkyl group; more preferably, R' and R" are independently selected from C1 to C6 alkyl groups; even more preferably, R' and R" are independently selected from methyl, ethyl, propyl, phenyl, cyclopentyl, or cyclohexyl; even more preferably, both R' and R" are selected from methyl or ethyl. y is an integer from 1 to 6, preferably, y is an integer from 1 to 4.

[0023] The polyamic acid ester of this invention has an X group, which is derived from a diamine necessary for the synthesis of polyimides. The X group is selected from substituted or unsubstituted C6-C6 groups. 30 Aryl; preferably, the X is selected from substituted or unsubstituted C. 12 ~C 30 Aryl.

[0024] More preferably, X is selected from the groups with structures shown in Formula X-1 to Formula X-5;

[0025]

[0026] More preferably, X is selected from groups with structures shown in formulas Xa to Xh;

[0027]

[0028] The polyamic acid ester of this invention also has an Ar1 group, which is derived from the dicarboxylic acid anhydride necessary for the synthesis of polyimide, and has a structure containing at least one aromatic ring or aliphatic ring. Specifically, the Ar1 is selected from substituted or unsubstituted C4-C6 cycloalkyl groups or substituted or unsubstituted C6-C6 cycloalkyl groups. 30 Aryl.

[0029] Preferably, the Ar1 is selected from groups with structures shown in formulas Ar1-1 to Ar1-12;

[0030]

[0031] More preferably, the Ar1 is selected from groups with structures shown in formulas Ar1-a to Ar1-r;

[0032]

[0033] 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:

[0034] reacting a dianhydride having a structure of Formula 1 with an alcohol amine having a structure of Formula 2, and then reacting the resultant product with a diamine having a structure of Formula 3 to obtain a polyamic ester.

[0035] H2N-X-NH2 Formula 3.

[0036] The present application further comprises activating the resultant product before reacting the resultant product with a diamine having a structure of Formula 3. The activation in the present application refers to a method for activating carboxyl group for reacting with amine group. The activation method in the present application specifically refers to adding an amide condensing agent formed by carboxylic acid and amine group, for example, the amide condensing agent is carbodiimide, carbonyl diimidazole, carbonium salt or organic phosphorus condensing agent; preferably carbodiimide or carbonyl diimidazole condensing agent; more preferably dicyclohexyl carbodiimide (DCC), diisopropyl carbodiimide (DIC) or 1-(3-dimethyl aminopropyl)-3-ethyl carbodiimide (EDCI). Alternatively, the activation refers to converting carboxyl group into acyl halide, which can then react with amine group; for example, converting carboxyl group into acyl halide using conventional acyl halide reagent, which can be thionyl halide, phosphorus oxyhalide or carbon oxyhalide, preferably thionyl chloride (SOCl2), phosphorus oxychloride or oxalyl chloride.

[0037] The present application first reacts a dianhydride having a structure of Formula 1 with an alcohol amine having a structure of Formula 2, specifically, under a protective gas atmosphere, reacting the dianhydride having a structure of Formula 1 with the alcohol amine having a structure of Formula 2 at 0-60°C for 5-7h, and then reacting the resultant product with an amide condensing agent, or reacting the resultant product with an acyl halide reagent at -5-5°C for 3-7h, and then reacting the resultant product with a diamine having a structure of Formula 3 at -5-5°C for 11-13h to obtain a polyamic ester.

[0038] More specifically, under a protective gas atmosphere, reacting the dianhydride having a structure of Formula 1 with the alcohol amine having a structure of Formula 2 at 0-60°C for 5-7h, and then reacting the resultant product with dicyclohexyl carbodiimide, or reacting the resultant product with thionyl chloride at -5-5°C for 3-7h, and then reacting the resultant product with a diamine having a structure of Formula 3 at -5-5°C for 11-13h to obtain a polyamic ester.

[0039] 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, an alcohol amine having the structure of Formula 2 is added thereto, and the reaction is carried out at a temperature of 0°C to 60°C for 5h to 7h, then the reaction product obtained and dicyclohexyl carbodiimide, or and sulfoxide chloride, are reacted at -5°C to 5°C for 3h to 7h, and then the diamin having the structure of Formula 3 is stirred and reacted at -5°C to 5°C for 11h to 13h to obtain a polyamic acid ester solution, which is precipitated by ethanol to obtain a polyamic acid ester solid powder.

[0040] The molar ratio of the dianhydride having the structure of Formula 1, the alcohol amine having the structure of Formula 2, and the diamin having the structure of Formula 3 according to the present application is (0.8-1.2):(1.6-2.0):1, for example, 0.8:(1.6-2.0):1, for example, 0.9:(1.6-2.0):1, for example, 1.0:(1.6-2.0):1, for example, 1.1:(1.6-2.0):1, for example, 1.2:(1.6-2.0):1. The ratio of the amount of the amide condensing agent or acyl halide reagent according to the present application and the amount of the diamin having the structure of Formula 3 is (1.6-2.4):1. The protective gas according to the present application is selected from one or more of nitrogen, helium, neon, and argon. The organic solvent according to the present application is selected from one or more of DMF, DMAc, NMP, and butyrolactone.

[0041] The dianhydride having the structure of Formula 1 is selected from at least one of 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,4,5-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-benzenetetracarboxylic dianhydride, 3,4,3',4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 2,3,2',3'-biphenyltetracarboxylic dianhydride, 3,4,3',4'-benzophenonetetracarboxylic dianhydride, 2,3,3',4'-benzophenonetetracarboxylic 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-naphthalenetetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 3,4-dicarboxybenzoic acid-(3,4-dicarboxyphenol) ester dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, and 4,4'-oxydiphthalic anhydride. Preferably, the dianhydride having the structure of Formula 1 is selected from 1,2,4,5-benzenetetracarboxylic dianhydride, 3,4,3',4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 2,3,2',3'-biphenyltetracarboxylic dianhydride, 3,4,3',4'-diphenyl ether tetracarboxylic dianhydride, or 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride.

[0042] The alcohol amine having the structure of Formula 2 is selected from at least one of dimethylaminoethanol, dimethylaminopropanol, dimethylaminopentanol, diethylaminopentanol, 4-dimethylaminophenol, 2-diphenylaminoethanol, 4-diphenylaminophenol, and 2-diphenylaminomethanol.

[0043] The diamine having the structure of Formula 3 is 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, and 4,4'-bis(3-aminophenoxy)biphenyl. Preferably, the 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.

[0044] The present application also provides a method for preparing the aqueous sizing agent of any of the above, comprising the steps of:

[0045] The polyamide acid ester, water and surfactant are mixed at a temperature of 20℃ to 40℃ to obtain the water-based sizing agent. Specifically, the water and surfactant are added to the polyamide acid ester while stirring to obtain the water-based sizing agent; the water is added at a speed of 2.5g / min to 3.5g / min. Preferably, the water is added at a speed of 2g / min.

[0046] The water-based sizing agent provided by the present application can be used in the immersion sizing process to adhere to the surface of the carbon fiber, and the component polyamide ester in the water-based sizing agent is subjected to thermal imidization to obtain polyimide and is solidified on the surface of the carbon fiber after a heating process at 200℃ to 400℃. The polyimide obtained by the present application has the structure of Formula II.

[0047]

[0048] wherein Ar1, X and n are the same as described above and are not repeated.

[0049] The present application also provides a sizing method of carbon fiber material, which comprises the following steps:

[0050] The carbon fiber material is subjected to sizing in the dilute solution of the sizing agent, and then is subjected to heat treatment at 200℃ to 400℃; the sizing agent is selected from the water-based sizing agent of any of the above technical solutions or the water-based sizing agent obtained by the preparation method of any of the above technical solutions.

[0051] Specifically, the carbon fiber material is subjected to sizing by being immersed in the sizing agent, is taken out after the sizing is completed, and then is subjected to heat treatment at 200℃ to 400℃, and finally is subjected to drying. Preferably, the time for the sizing is 80s to 100s. Preferably, the mass fraction of the dilute solution of the sizing agent is 2% to 5%.

[0052] The present application also provides a sized carbon fiber material, which is obtained by treating the carbon fiber material with the water-based sizing agent of any of the above technical solutions or the water-based sizing agent obtained by the preparation method of any of the above technical solutions.

[0053] The present application provides a water-based sizing agent based on photosensitive polyimide, a preparation method thereof, a sizing method of carbon fiber material, and a sized carbon fiber material. The component polyamide ester in the water-based sizing agent provided by the present application has a simple and fast synthesis method and a novel and diverse structure. After the carbon fiber material is treated with the water-based sizing agent, the polyamide ester is also subjected to thermal imidization to obtain a polyimide with a novel and diverse structure. The water-based sizing agent provided by the present application has good water solubility, excellent sizing amount for the carbon fiber, 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 water-based sizing agent provided by the present application is greater than 0.8. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 Flow chart for preparation of polyamic acid ester according to the present application.

[0055] Figure 2 Flow chart for thermal imidization of polyamic acid ester according to the present application to polyimide. DETAILED DESCRIPTION

[0056] The application discloses a photosensitive polyimide-based water-based sizing agent and a preparation method thereof, a sizing method of 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 present application. The method and application of the present application have been described through preferred embodiments, and relevant personnel can obviously make changes or appropriate changes and combinations to the method and application herein without departing from the content, spirit and scope of the present application, to realize and apply the present application technology.

[0057] The present application first prepares a polyamic acid ester, and then performs sizing agent configuration, as shown in Figure 1 Figure 1 Flow chart for preparation of polyamic acid ester according to the present application.

[0058] The present application is further described below in combination with examples:

[0059] Example 1

[0060] 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 stirring was performed at 0 DEG C for 6 h. Into the bottle, dichlorosulfoxide SOCl2 (322.2 mmol, 38.0 g) was added, stirring was performed at 0 DEG C for 3 h, 4,4'-oxydianiline ODA (161.1 mmol, 32.2 g) was added, stirring was performed at 0 DEG C for 12 h, and the obtained polyamic acid ester solution was precipitated with ethanol to obtain a yellow polyamic acid ester powder.

[0061] Sizing agent configuration: 3 g of the polyamic acid ester powder was weighed, deionized water was added dropwise under stirring at a temperature of 30 DEG C, the stirring speed was 200 r / min, the mass of water added to the mixture per minute was 3 g, and 0.15 g of polyether-modified polysiloxane was added simultaneously during the addition of water; 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 experiments.

[0062] Example 2​

[0063] Into a reaction vessel, add 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) successively, and stir at -5°C for 6 h. Into the bottle, add dichlorosulfoxide SOCl2 (322.2 mmol, 38.0 g), and stir at 5°C for 7 h. Add 4,4'-oxydianiline ODA (161.1 mmol, 32.2 g), and stir at 5°C for 13 h. The obtained polyamic acid ester solution is precipitated with ethanol to obtain a light yellow polyamic acid ester powder.

[0064] Sizing agent preparation: weigh 3 g of the polyamic acid ester powder, and add deionized water dropwise while stirring at 30°C. The stirring speed is 200 r / min, and the mass of water added to the mixture per minute is 3 g. During the water addition, 0.15 g of sodium dodecyl sulfonate is added simultaneously. When 250 g of water is added, a transparent, uniform, and stable water-soluble polyimide resin solution with a solid content of 1.5 wt% is obtained, which is the polyimide sizing agent and is used for sizing test experiments.

[0065] Example 3

[0066] Into a reaction vessel, add 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) successively, and stir at -5°C for 6 h. Into the bottle, add dichlorosulfoxide SOCl2 (322.2 mmol, 38.0 g), and stir at 5°C for 7 h. Add 4,4'-oxydianiline ODA (161.1 mmol, 32.2 g), and stir at 5°C for 13 h. The obtained polyamic acid ester solution is precipitated with ethanol to obtain a light yellow polyamic acid ester powder.

[0067] Sizing agent preparation: weigh 3 g of the polyamic acid ester powder, and add deionized water dropwise while stirring at 30°C. The stirring speed is 200 r / min, and the mass of water added to the mixture per minute is 3 g. During the water addition, 0.15 g of sodium dodecyl sulfonate is added simultaneously. When 250 g of water is added, a transparent, uniform, and stable water-soluble polyimide resin solution with a solid content of 1.5 wt% is obtained, which is the polyimide sizing agent and is used for sizing test experiments.

[0068] Example 4

[0069] 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 added successively, and the reaction was stirred at 5°C for 7 h. Into the bottle, dichlorosulfoxide DCC (322.2 mmol, 66.5 g) was added, and the reaction was stirred at -5°C for 6 h, 4,4'-diaminodiphenyl sulfone DDS (161.1 mmol, 40.0 g) was added, and the reaction was stirred at -5°C for 11 h, to obtain a polyamic acid ester solution, which was precipitated with ethanol to obtain a yellow polyamic acid ester powder.

[0070] Sizing agent preparation: 3 g of the polyamic acid 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 the polysiloxane was added, to obtain a transparent, uniform, and stable water-soluble polyimide resin solution with a solid content of 1.5 wt%, which was used as a polyimide sizing agent for sizing test experiments.

[0071] Example 5

[0072] 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 added successively, and the reaction was stirred at 3°C for 7 h. Into the bottle, dichlorosulfoxide SOCl2 (322.2 mmol, 38.0 g) was added, and the reaction was stirred at 3°C for 5 h, 1,4-cyclohexanediamine CHDA (161.1 mmol, 18.4 g) was added, and the reaction was stirred at 5°C for 13 h, to obtain a polyamic acid ester solution, which was precipitated with ethanol to obtain a yellow polyamic acid ester powder.

[0073] Sizing agent preparation: 3 g of the polyamic acid 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 the polysiloxane was added, to obtain a transparent, uniform, and stable water-soluble polyimide resin solution with a solid content of 1.5 wt%, which was used as a polyimide sizing agent for sizing test experiments.

[0074] Example 6

[0075] 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), dimethylamino propanol (322.2 mmol, 33.2 g) were added successively, and the reaction was stirred at 60 °C for 7 h. Into the bottle, DCC (322.2 mmol, 66.5 g) was added, and the reaction was stirred at 0 °C for 3 h. 4,4'-diaminodiphenyl ether ODA (161.1 mmol, 32.2 g) was added, and the reaction was stirred at -5 °C for 11 h. The obtained polyamic acid ester solution was precipitated with ethanol to obtain a yellow polyamic acid ester powder.

[0076] Sizing agent preparation: 3 g of the polyamic acid 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. 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 subjected to sizing test experiments.

[0077] Example 7

[0078] 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), dimethylamino propanol (322.2 mmol, 33.2 g) were added successively, and the reaction was stirred at 60 °C for 7 h. Into the bottle, DCC (322.2 mmol, 66.5 g) was added, and the reaction was stirred at 0 °C for 3 h. 4,4'-diaminodiphenyl ether ODA (161.1 mmol, 32.2 g) was added, and the reaction was stirred at -5 °C for 11 h. The obtained polyamic acid ester solution was precipitated with ethanol to obtain a yellow polyamic acid ester powder.

[0079] Sizing agent preparation: 3 g of the polyamic acid 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. 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 subjected to sizing test experiments.

[0080] Example 8

[0081] 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), diethylaminopentanol (322.2 mmol, 49.9 g) were added successively, and the reaction was stirred at 0 °C for 6 h. Into the bottle, DCC (322.2 mmol, 66.5 g) was added, and the reaction was stirred at 0 °C for 3 h, 4,4'-oxydianiline ODA (161.1 mmol, 32.2 g) was added, and the reaction was stirred at 0 °C for 12 h, to obtain a polyamic acid ester solution, which was precipitated with ethanol to obtain a yellow polyamic acid ester powder.

[0082] Sizing agent preparation: 3 g of the polyamic acid ester powder was weighed, and deionized water was added dropwise while stirring at 30 °C, the stirring speed was 200 r / min, and the mass of water added to the mixture per minute was 3 g, 0.15 g of polyether-modified polysiloxane was added during the addition of water, and 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 the polyimide sizing agent and was subjected to sizing test experiments.

[0083] Comparative Example 1

[0084] 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), diethylaminopentanol (322.2 mmol, 49.9 g) were added successively, and the reaction was stirred at 0 °C for 6 h. Into the bottle, DCC (322.2 mmol, 66.5 g) was added, and the reaction was stirred at 0 °C for 3 h, 4,4'-oxydianiline ODA (161.1 mmol, 32.2 g) was added, and the reaction was stirred at 0 °C for 12 h, to obtain a polyamic acid ester solution, which was precipitated with ethanol to obtain a yellow polyamic acid ester powder.

[0085] Sizing agent preparation: 3 g of the polyamic acid ester powder was weighed, and deionized water was added dropwise while stirring at 30 °C, the stirring speed was 200 r / min, and the mass of water added to the mixture per minute was 3 g, 0.15 g of polyether-modified polysiloxane was added during the addition of water, and 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 the polyimide sizing agent and was subjected to sizing test experiments.

[0086] Comparative Example 2

[0087] 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), dimethylamino nonanol (322.2 mmol, 49.9 g) were added successively, and the mixture was stirred at 0°C for 6 h. Into the bottle, dicyclohexyl carbodiimide DCC (322.2 mmol, 66.4 g), 4,4'-diamino diphenyl ether ODA (161.1 mmol, 32.2 g) were added, and the mixture was stirred at 0°C for 12 h. The obtained polyamide ester solution was precipitated with ethanol to obtain a yellow polyamide ester powder.

[0088] Sizing agent preparation: 3 g of the polyamide ester powder was weighed, and deionized water was added dropwise while stirring at 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. After the addition of water, a transparent, uniform, and stable water-soluble polyimide resin solution could not be obtained.

[0089] Comparative Example 3

[0090] 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), 4-dimethylaminophenol (322.2 mmol, 44.1 g) were added successively, and the mixture was stirred at 0°C for 6 h. Into the bottle, dicyclohexyl carbodiimide DCC (322.2 mmol, 66.4 g), 4,4'-diamino diphenyl ether ODA (161.1 mmol, 32.2 g) were added, and the mixture was stirred at 0°C for 12 h. The obtained polyamide ester solution was precipitated with ethanol to obtain a yellow polyamide ester powder.

[0091] Sizing agent preparation: 3 g of the polyamide ester powder was weighed, and deionized water was added dropwise while stirring at 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 added. After the addition of water, a transparent, uniform, and stable water-soluble polyimide resin solution could not be obtained.

[0092] Comparative Example 4

[0093] 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), N-methyl-2-hydroxyethylamine (322.2 mmol, 24.2 g) were added successively, and the reaction was stirred at 0 °C for 6 h. Into the bottle, dicyclohexyl carbodiimide DCC (322.2 mmol, 66.4 g), 4,4'-diamino diphenyl ether ODA (161.1 mmol, 32.2 g) were added, and the reaction was stirred at 0 °C for 12 h. The polyamide ester solution was precipitated with ethanol to obtain a yellow polyamide ester powder.

[0094] Comparative Example 5

[0095] Into a reaction vessel, 4,4'-oxydiphthalic anhydride ODPA (161.1 mmol, 50.0 g), 4,4'-diamino diphenyl ether ODA (161.1 mmol, 32.2 g), DMF (184 g) were added successively, and the reaction was stirred at 0 °C for 6 h. Into the bottle, triethylamine (322.2 mmol, 16.3 g) was added, and the reaction was stirred at room temperature for 3 h. The obtained polyamide acid salt solution was precipitated with ethanol to obtain a yellow polyamide acid salt powder.

[0096] Sizing agent preparation: 3 g of the polyamide salt 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. 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 the polyimide sizing agent and was used for sizing test experiments.

[0097] Comparative Example 6

[0098] 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), 4-dimethylamino phenol (322.2 mmol, 44.2 g) were added successively, 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. 4,4'-diamino diphenyl ether ODA (161.1 mmol, 32.2 g) was added, and the reaction was stirred at 0 °C for 12 h. The obtained polyamide acid ester solution was precipitated with ethanol to obtain a yellow polyamide acid ester powder.

[0099] 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 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. 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 the polyimide sizing agent and was used for sizing test experiments.

[0100] Performance test:

[0101] (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 it completely dissolved within 0.2 h, it was extremely soluble; if it completely dissolved within 0.5 h, it was soluble; if it completely dissolved within 1 h, it was soluble; and if it did not dissolve or precipitates or gels were observed within 1 h, it was insoluble.

[0102] (2) Sizing test experiment: carbon fiber filaments without sizing agent on the surface were immersed in the sizing agent for 90 s, taken out, and dried at a furnace temperature of 300°C for 5 min. During this process, the polyamide acid ester in the sizing agent was thermally imidized to become polyimide, as shown in Figure 2 , Figure 2 which is a flowchart of the thermal imidization of the polyamide acid ester to polyimide according to the present application.

[0103] Carbon fiber sizing amount: using the property that the sizing agent can be dissolved in acetone, the sizing agent on the surface of the carbon fiber was extracted by the extraction reflux method. The mass of the fiber before desizing (W i ) and the mass after desizing (W f ) were weighed, and the mass difference was calculated to calculate the sizing amount. The sizing amount was calculated according to the following formula:

[0104]

[0105] (3) Interfacial shear strength: resin droplets were solidified on the monofilament fiber, the debonding force was measured, and the interfacial shear strength was calculated.

[0106] The results are shown in Table 1:

[0107] Table 1

[0108]

[0109]

[0110] 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, the water-soluble polyamic acid ester can be obtained by the method, and the mechanical properties of the polyimide obtained by thermal imidization are not lost, and the sizing amount is greater than 0.80%. The polyamic acid ester powder obtained in Comparative Examples 1-3 has poor solubility, and the water-soluble polyamic acid ester cannot be obtained, and the mechanical properties of the polyimide obtained by thermal imidization are reduced. In Comparative Examples 4-6, when the alcohol amine is a primary amine or a secondary amine, the corresponding water-soluble polyamic acid ester powder cannot be obtained, which may be due to the competition reaction caused by the amine group, so that the polymerization cannot proceed normally.

[0111] The above merely describes the preferred 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 according to the technical solution 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, In 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; X is selected from substituted or unsubstituted C6-C6. 30 Aryl; said Ar1is selected from substituted or unsubstituted C4to C6cycloalkyl or substituted or unsubstituted C6to C10aryl; 30 aryl; The R' and R" are independently selected from substituted or unsubstituted alkyl with carbon number less than 15, substituted or unsubstituted heteroalkyl with carbon number less than 15, substituted or unsubstituted aryl with carbon number less than 15 or substituted or unsubstituted heteroaryl with carbon number less than 15; The y is an integer of 1 to 6.

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; polyether modified polysiloxane: 0.1 parts to 0.2 parts; Water: 200 parts; Or, comprising: Polyamide acid ester: 2.5 parts to 3.5 parts; sodium dodecyl sulfonate: 0.1 parts to 0.2 parts; water: 250 parts; Or, comprising: Polyamide acid ester: 2.5 parts to 3.5 parts; polyether modified dimethyl polysiloxane: 0.1 parts to 0.2 parts; water: 200 parts; Or, comprising: Polyamide acid ester: 2.5 parts to 3.5 parts; polysiloxane: 0.1 parts to 0.2 parts; water: 200 parts; Or, comprising: Polyamide acid ester: 2.5 parts to 3.5 parts; lauric acid: 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, dimethyl polysiloxane, polyester modified organosiloxane, alkyl modified organosiloxane, polyether modified silicone oil, lauric acid, palmitic acid trialkyl melamine.

5. The aqueous sizing agent according to any one of claims 1 to 4, characterized in that, said R' and R" are independently selected from C1to C4alkyl; 12 alkyl; 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 dianhydride with structure of formula 1 and alcohol amine with structure of formula 2, and then reacting the product with diamine with structure of formula 3 to obtain polyamide acid ester; H2N-X-NH2Formula 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 polyamide acid ester, water and surfactant at temperature of 20℃ to 40℃ to obtain aqueous sizing agent.

8. A method of sizing a carbon fiber material, characterized by, Comprising the following steps: Sizing carbon fiber material in dilute solution of sizing agent, and then heat treating at 200℃ to 400℃; The sizing agent is selected from aqueous sizing agent of any one of claims 1-6 or aqueous sizing agent prepared 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% to 5%.

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

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