Water-soluble polyether amide acid salt sizing agent, preparation method and application thereof

Abstract

The application relates to the technical field of sizing agents for fibers, and discloses a water-soluble polyether amide acid salt sizing agent and a preparation method and application thereof. The sizing agent comprises polyether amide acid salt and water, wherein the polyether amide acid salt contains amide acid groups and ether bonds, the content of the polyether amide acid salt is 0.1-50% by weight based on the total weight of the sizing agent, and the content of water is 50-99.9% by weight. The sizing agent has the advantages of water solubility, absence of organic solvents and surfactants, moderate stiffness of the sized fiber, and high interlayer shear strength between the fiber and the resin.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sizing agent for fibers, in particular to a water-soluble polyether amide acid salt sizing agent and a preparation method and application thereof. BACKGROUND

[0002] Carbon fiber is a new type of material with high specific strength and specific modulus. However, it is brittle and has low elongation. In order to avoid problems such as fuzzing and breaking, sizing is an essential step in the production process of carbon fiber.

[0003] After sizing, the sizing agent will spread on the surface of the carbon fiber to form a functional organic polymer layer, which can improve the wear resistance, bundling and spreading performance of the carbon fiber, and reduce the fuzz of the carbon fiber. On the other hand, the polymer layer on the surface of the sized carbon fiber can improve the interfacial properties between the carbon fiber and the resin, and increase the performance of the carbon fiber composite material.

[0004] Recently, sizing agents commonly used in thermoplastic systems are water-soluble polyimide sizing agents. However, the polyether amide sizing agent prepared by the powder dispersion method uses a large amount of surfactant, which affects the dispersion of polyether amide on the surface of carbon fiber. The polyether amide sizing agent prepared by the organic solvent method will have organic solvent volatilization during use, which is not conducive to the operating environment.

[0005] Therefore, it is of great significance to research and develop a sizing agent. SUMMARY

[0006] The present application aims to overcome the defects of the polyether amide sizing agent prepared by the organic solvent method and the powder dispersion method in the prior art, which has poor sizing effect and is not environmentally friendly. The present application provides a water-soluble polyether amide acid salt sizing agent and a preparation method and application thereof. The sizing agent has the advantages of water solubility, no organic solvent and no surfactant, moderate stiffness of the sized fiber, and high interlaminar shear strength of the fiber and resin.

[0007] In order to achieve the above-mentioned purpose, the present application provides a water-soluble polyether amide acid salt sizing agent, wherein the sizing agent comprises polyether amide acid salt and water, wherein the polyether amide acid salt contains amide acid groups and ether bonds, and the content of the polyether amide acid salt is 0.1-50 wt% and the content of water is 50-99.9 wt% based on the total weight of the sizing agent.

[0008] The present application provides a preparation method of a water-soluble polyether amide acid salt sizing agent, wherein the preparation method comprises:

[0009] (1) polyetherimide is contacted with a first base to perform a flexible treatment to obtain a mixed solution; the mixed solution is then contacted with an acid to perform a first neutralization reaction, and is subjected to filtration, washing and drying treatment to obtain polyether amic acid;

[0010] (2) the polyether amic acid is dispersed in a solvent and then contacted with a second base to perform a second neutralization reaction to obtain polyether amic acid salt;

[0011] (3) the polyether amic acid salt is dissolved in water to obtain a water-soluble polyether amic acid salt sizing agent.

[0012] The third aspect of the present application provides a water-soluble polyether amic acid salt sizing agent prepared by the preparation method described above.

[0013] The fourth aspect of the present application provides an application of the water-soluble polyether amic acid salt sizing agent described above to surface modification of fibers.

[0014] Through the above technical solution, the water-soluble polyether amic acid salt sizing agent of the present application is used, the processing performance of the sized fiber (for example, carbon fiber) is better, at the same time, the production process is safer, and the stability is high, and the fiber and resin matrix interface strength can be improved, so that the mechanical properties of the composite material are improved. In addition, the sizing agent of the present application does not contain surfactants and other components that affect the sizing effect, and also does not contain organic solvents, so that the operating environment is more mild. DETAILED DESCRIPTION

[0015] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and any values are understood to be approximate values. The exact numerical values of the endpoints of the ranges and any values are approximations that allow for a reasonable range that will accommodate minor variations from the values that can result, for example, from round off error in reporting numeric values. Other values from the stated ranges and values can be included. The upper and lower values, and any numerical values, can be combined to form a range. Ranges can be included that are outside of the specific values recited if reasonably expected by one of ordinary skill in the art to fall within the scope of the application. The range format is only used for readability and thus should not be construed as limiting the scope of the application. Use of the word "about" means that the value provided or claimed can vary from the stated value by up to 10%, unless otherwise stated.

[0016] As described above, the first aspect of the present application provides a water-soluble polyether amic acid salt sizing agent, wherein the sizing agent comprises polyether amic acid salt and water, wherein the polyether amic acid salt contains amic acid groups and ether bonds, and the content of the polyether amic acid salt is 0.1-50% by weight and the content of water is 50-99.9% by weight based on the total weight of the sizing agent.

[0017] The inventors of the present application unexpectedly found that the sizing agent in the prior art, which is mainly used in thermoplastic systems, is a water-soluble polyetherimide sizing agent, which has strong chain rigidity, resulting in an increase in the stiffness of the sized fiber, which is not conducive to subsequent processing. However, by modifying the polyetherimide resin, the polyetherimide acid salt containing amide acid groups and ether bonds can be formed, which has good water solubility at low temperatures. After high-temperature treatment, the polyetherimide acid salt reverts to polyetherimide resin, which is no longer soluble in water, so that the performance of the sized fiber (preferably carbon fiber) is more stable. At the same time, compared with the existing polyetherimide sizing agent, the sizing agent of the present application does not contain surfactants and organic solvents, which is safer in production process and has high stability and is not easy to precipitate, which can improve the interfacial strength of carbon fiber and resin matrix, and improve the mechanical properties of the composite material.

[0018] According to the present application, preferably, the content of the polyetherimide acid salt is 1-10% by weight and the content of water is 90-99% by weight, based on the total weight of the sizing agent. In the present application, the content of the polyetherimide acid salt and water is limited within the aforementioned range, which has the advantages of uniform sizing and good bundling.

[0019] According to the present application, the polyetherimide acid salt has a structure represented by formula (1):

[0020]

[0021] Formula (1);

[0022] wherein the molar ratio of x and y is (0-26):(73-100); preferably, the molar ratio of x:y is (0-5):(93-100).

[0023] wherein R1 is selected from one or more of H, CH3, C2H5, C3H7, ph, CH2OH, CH2NH2, OH and NH2;

[0024] R2 is selected from one or more of H, CH3, C2H5, C3H7, ph, CH2OH, CH2NH2, OH and NH2;

[0025] R3 is selected from one or more of protonated triethylamine, diethylamine, n-propylamine, n-butylamine, cyclohexylamine, ethylenediamine, benzylamine, aniline, N-toluidine, N,N'-dimethylaniline, diphenylamine, triphenylamine, o-toluidine, m-toluidine and p-toluidine cation;

[0026] Ar is selected from one or more of .

[0027] The present application provides a preparation method of a water-soluble polyetherimide acid salt sizing agent, wherein the preparation method comprises:

[0028] (1) contacting the polyetherimide with a first base to perform a flexible treatment to obtain a mixed solution; then contacting the mixed solution with an acid to perform a first neutralization reaction, and performing a filtering, washing and drying treatment to obtain a polyether amic acid;

[0029] (2) dispersing the polyether amic acid in a solvent and then contacting with a second base to perform a second neutralization reaction to obtain a polyether amic acid salt;

[0030] (3) dissolving the polyether amic acid salt in water to obtain a water-soluble polyether amic acid salt sizing agent.

[0031] According to the present application, the polyetherimide is a polymer having an imide group and an ether bond in the repeating unit of the molecular chain; preferably, the polyetherimide is selected from one or more of Ultem 1000, Ultem 1000F, Ultem 1000P, Ultem 1000R, Ultem LTX300A, Ultem LTX300B and Ultem HTX1010F resins.

[0032] According to the present application, the first base is selected from one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide and ammonia; in the present application, the concentration of the first base is 1-40%.

[0033] According to the present application, the acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid and acetic acid; in the present application, the concentration of the hydrochloric acid is 0.1-36%, the concentration of the sulfuric acid is 0.1-98%, the concentration of the nitric acid is 0.1-67%, and the concentration of the acetic acid is 0.1-98%.

[0034] According to the present application, the amount of the first base is 1-1000 mL and the amount of the acid is 1-1000 mL with respect to 1 g of the polyetherimide; preferably, the amount of the first base is 10-100 mL and the amount of the acid is 10-100 mL with respect to 1 g of the polyetherimide.

[0035] According to the present application, in step (1), the conditions of the flexible treatment include a temperature of 10-130℃ and a time of 0.5-16h; preferably, the temperature is 70-130℃ and the time is 1-4h.

[0036] According to the present application, in step (1), the mixed solution is contacted with an acid to perform a first neutralization reaction to produce a precipitate, which is filtered, washed with deionized water and dried to obtain a polyether amic acid; wherein the filtering can use common filtering or suction filtering, the drying temperature is 80-130℃ and the time is 1-40h.

[0037] According to the present application, in step (1), the conditions for the first neutralization reaction of the mixed solution with the acid include: temperature of 10-130℃, time of 0.5-16h; preferably, temperature of 40-100℃, time of 1-8h.

[0038] According to the present application, the second base is selected from one or more of triethylamine, diethylamine, n-propylamine, n-butylamine, cyclohexylamine, ethylenediamine, benzylamine, aniline, N-methylaniline, N,N'-dimethylaniline, diphenylamine, triphenylamine, o-toluidine, m-toluidine and p-toluidine.

[0039] According to the present application, the solvent is selected from one or more of water, ethanol, methanol, tetrahydrofuran and dioxane.

[0040] According to the present application, in step (2), the conditions for the second neutralization reaction of the polyether amide acid with the second base include: temperature of 10-130℃, time of 0.5-16h; preferably, temperature of 20-50℃, time of 1-8h.

[0041] According to the present application, the amount of the second base is 0.1-100g, and the amount of the polyether amide acid is 0.1-100g, relative to 100mL of the solvent; preferably, the amount of the second base is 1-40g, and the amount of the polyether amide acid is 1-40g, relative to 100mL of the solvent.

[0042] According to the present application, in step (3), the weight ratio of the amount of the polyether amide acid salt to the amount of water is (0.1-50):(50-99.9); preferably, the weight ratio of the amount of the polyether amide acid salt to the amount of water is (1-10):(99-90).

[0043] According to the present application, in step (3), the conditions for dissolving the polyether amide acid salt in water include: temperature of 10-80℃, preferably 40-70℃. In the present application, preferably, the process is carried out under stirring at a stirring rate of 10-400rpm.

[0044] According to a preferred embodiment of the present application, the preparation method of the water-soluble polyether amide acid salt sizing agent comprises:

[0045] (1) one or several polyether imide resins are put into a flask, a first base solution is added, stirred until dissolved, and the reaction solution is kept at 70-130℃ for 1-4h for flexible treatment, to obtain a mixed solution, after the reaction, an acid solution is added to the obtained product for first neutralization reaction, until precipitation is generated, filtered, washed with deionized water, dried, and polyether amide acid resin is prepared.

[0046] (2) The polyether amide acid resin is dispersed in a solvent, and a second alkali solution is added to perform a second neutralization reaction, so that the polyether amide acid resin is dissolved, the insoluble substances are filtered, the filtrate is collected, and low-temperature drying is performed to obtain a water-soluble polyether amide acid salt resin.

[0047] (3) The water-soluble polyether amide acid salt resin is dissolved in water at a temperature of 40-70°C, and stirring is performed to obtain a water-soluble polyether amide acid salt sizing agent.

[0048] According to a particularly preferred embodiment of the present application, in the present application, the reaction path of the water-soluble polyether amide acid salt sizing agent comprises:

[0049]

[0050]

[0051] The third aspect of the present application provides a water-soluble polyether amide acid salt sizing agent prepared by the preparation method.

[0052] The fourth aspect of the present application provides an application of the water-soluble polyether amide acid salt sizing agent to surface modification of fibers.

[0053] According to the present application, the fibers include carbon fibers and / or graphite fibers, and preferably carbon fibers.

[0054] According to a preferred embodiment of the present application, the method for surface modification of carbon fibers by using the water-soluble polyether amide acid salt sizing agent comprises:

[0055] The water-soluble polyether amide acid salt sizing agent is placed in a sizing tank, and the unsized carbon fibers are immersed in the sizing agent and pass through the sizing tank at a speed of 0.1 m / min-1 m / min, the sizing time is 30 s-2.5 min, the excess sizing agent of the carbon fibers out of the tank is squeezed out, and then the sized carbon fibers are dried at a gradient temperature of 100°C, 130°C, 160°C, 180°C, 200°C, 220°C, and 260°C.

[0056] The sized carbon fibers can be used to prepare thermoplastic composites at high temperature, which improves the compatibility of the carbon fiber / resin interface and improves the toughness, strength, and ductility of the composite material.

[0057] According to the present application, the amount of the fibers is 5-5000 g, and preferably 100-1000 g, relative to 100 mL of the sizing agent.

[0058] The present application will be described in detail through the following examples.

[0059] In the following examples and comparative examples:

[0060] Thermal stability parameters were measured by thermogravimetric method, with N2atmosphere, 10°C / min heating rate, and temperature range 100-800°C.

[0061] Polyetherimide raw material was purchased from commercially available product of Sabic Innovative Plastics.

[0062] Solubility test method: 1 g of modified thermoplastic resin was put into 100 g of solvent, and magnetic stirring was performed for 1 h, and whether there was solid residue was observed.

[0063] Stiffness test: a certain length of fiber sample was hung at the midpoint, and after stabilization, the distance between the two ends of the sample at a certain standard distance below the fiber hanging point was measured. Three one-meter-long fiber samples were cut and placed in a standard temperature and humidity environment, and allowed to stand for at least 16 h to reach moisture equilibrium. One-meter-long fiber tows were hung at the midpoint, and the two ends were knotted, and the lower end was hung with a 400 g load. The bending and twisting of the fiber tows were corrected. After standing for 30 min under standard temperature and humidity conditions, the load was removed, and two 40 cm long tows were cut from each tow. The 40 cm sample was hung at the midpoint on the hooks of the stiffness tester. After 60 s of standing, the distance between the two ends of the hanging sample was quickly read.

[0064] Interlaminar shear strength test method: a single fiber was fixed on a self-made glass mold, a small amount of polyetherimide powder was dipped with a needle tip and applied to the fiber to form a point, and the microbeads were spontaneously formed by heating and melting at 300°C on a flat plate vulcanizing machine. According to the micro-detachment test method, the interfacial strength was tested, and the microbead coating length was observed under a microscope. Fibers with a coating length of 100-170 μm were selected and passed through a self-made clamp with micro-holes to fix the microbeads in the micro-holes of the clamp. The clamp was placed on a single fiber strength tester, and the length was set to 10 mm and the stretching speed was 2 mm / min.

[0065] Example 1

[0066] This example is directed to a sizing agent prepared by the method of the present application.

[0067] (1) 4.5 g of Ultem 1000 polyetherimide and 100 mL of 40% sodium hydroxide aqueous solution were mixed, heated to 40°C and stirred until dissolved, then heated to 70°C and maintained for 4 h; after the reaction was completed, 100 mL of 10% hydrochloric acid was added, the precipitate was filtered, washed with deionized water, and dried at 130°C for 12 h to obtain a polyether amide acid product;

[0068] (2) 9 g of polyether amide acid was dispersed in 45 g of water, stirred, 4 g of n-butylamine was added, heated to 40°C, and maintained for 4 h. The obtained solution was filtered and dried at 90°C to obtain a polyether amide acid n-butylamine salt;

[0069] (3) 10 g of polyether amide acid n-butylamine salt was dissolved in 90 g of water, heated to 50°C, stirred for 2 h to obtain a water-soluble polyether amide acid salt sizing agent.

[0070] Among them, the content of the polyether amide acid salt is 10% by weight, and the content of water is 90% by weight, based on the total weight of the sizing agent.

[0071] And the structural formula of the prepared polyether amide acid salt is:

[0072]

[0073] Among them: x:y = 0:100.

[0074] The water-soluble polyether amide acid salt sizing agent was placed in the sizing tank, the unsized carbon fiber was immersed in the sizing agent and passed through the sizing tank at 1 m / min, the sizing time was 30 s, the excess sizing agent of the out-of-tank carbon fiber was squeezed out, and then the sized carbon fiber was dried at 100°C, 130°C, 160°C, 180°C, 200°C, 220°C, 260°C in gradient.

[0075] Example 2

[0076] This embodiment is to illustrate the sizing agent prepared by the method of the application.

[0077] (1) 7 g of Ultem 1000 polyetherimide and 100 mL of 30% sodium hydroxide aqueous solution were mixed, heated to 40°C and stirred until dissolved, then heated to 100°C and kept for 4 h; after the reaction was completed, 200 mL of 20% hydrochloric acid was added, the precipitate was filtered, washed with deionized water, and dried at 130°C for 12 h to obtain a polyether amide acid product;

[0078] (2) 9 g of polyether amide acid was dispersed in 45 g of water, stirred, 3 g of n-butylamine was added, heated to 30°C and kept for 4 h, the obtained solution was filtered and dried at 90°C to obtain polyether amide acid n-butylamine salt;

[0079] (3) 5 g of polyether amide acid n-butylamine salt was dissolved in 95 g of water, heated to 50°C, stirred for 2 h to obtain a water-soluble polyether amide acid salt sizing agent.

[0080] Among them, the content of the polyether amide acid salt is 5% by weight, and the content of water is 95% by weight, based on the total weight of the sizing agent.

[0081] And the structural formula of the prepared polyether amide acid salt is:

[0082]

[0083] x:y=5:95.

[0084] The water-soluble polyether amide acid salt sizing agent is put into a sizing tank, the unsized carbon fiber is immersed in the sizing agent and passes through the sizing tank at 1 m / min, the sizing time is 30 s, the excess sizing agent of the carbon fiber out of the tank is squeezed out, and then the sized carbon fiber is dried at 100℃, 130℃, 160℃, 180℃, 200℃, 220℃ and 260℃ in gradient temperature rising.

[0085] Example 3

[0086] This example is to illustrate the sizing agent prepared by the method of the present application.

[0087] (1) 9 g of Ultem1000 polyetherimide and 100 mL of 20% sodium hydroxide aqueous solution are mixed, heated to 40℃ and stirred until dissolved, then heated to 130℃ and kept for 4 h; after the reaction is completed, 100 mL of 10% hydrochloric acid is added, the precipitate is filtered, washed with deionized water, and dried at 130℃ for 12 h to obtain a polyether amide acid product;

[0088] (2) 9 g of polyether amide acid is dispersed in 45 g of water, stirred, 2 g of n-butylamine is added, heated to 20℃ and kept for 4 h, the obtained solution is filtered and dried at 90℃ to obtain a polyether amide acid n-butylamine salt;

[0089] (3) 1 g of polyether amide acid n-butylamine salt is dissolved in 99 g of water, heated to 50℃ and stirred for 2 h to obtain a water-soluble polyether amide acid salt sizing agent.

[0090] Among them, the content of the polyether amide acid salt is 1% by weight and the content of water is 99% by weight based on the total weight of the sizing agent.

[0091] And the structural formula of the prepared polyether amide acid salt is:

[0092]

[0093] x:y=7:93.

[0094] The water-soluble polyether amide acid salt sizing agent is put into a sizing tank, the unsized carbon fiber is immersed in the sizing agent and passes through the sizing tank at 1 m / min, the sizing time is 30 s, the excess sizing agent of the carbon fiber out of the tank is squeezed out, and then the sized carbon fiber is dried at 100℃, 130℃, 160℃, 180℃, 200℃, 220℃ and 260℃ in gradient temperature rising.

[0095] Example 4

[0096] This example is to illustrate the sizing agent prepared by the method of the present application.

[0097] (1) 9g Ultem1000 polyetherimide and 100mL of 20% sodium hydroxide aqueous solution were mixed, heated to 40°C and stirred until dissolved, then warmed to 50°C and kept for 4h; after the reaction was completed, 200mL of 20% hydrochloric acid was added, the precipitate was filtered, washed with deionized water, and dried at 130°C for 12h to obtain a polyether amic acid product;

[0098] (2) 9g of the polyether amic acid was dispersed in 45g of water, stirred, 2g of n-butylamine was added, heated to 40°C and kept for 4h, the obtained solution was filtered and dried at 90°C to obtain a polyether amic acid n-butylamine salt;

[0099] (3) 0.5g of the polyether amic acid n-butylamine salt was dissolved in 99.5g of water, heated to 50°C and stirred for 2h to obtain a water-soluble polyether amic acid salt sizing agent.

[0100] The content of the polyether amic acid salt is 0.5% by weight and the content of water is 99.5% by weight, based on the total weight of the sizing agent.

[0101] The structural formula of the prepared polyether amic acid salt is:

[0102]

[0103] x:y = 17:83.

[0104] The water-soluble polyether amic acid salt sizing agent was placed in a sizing tank, the unsized carbon fiber was immersed in the sizing agent and passed through the sizing tank at 1m / min, the sizing time was 30s, the excess sizing agent of the carbon fiber out of the tank was squeezed out, and then the sized carbon fiber was dried at 100°C, 130°C, 160°C, 180°C, 200°C, 220°C and 260°C in gradient.

[0105] Example 5

[0106] This example is to illustrate the sizing agent prepared by the method of the present application.

[0107] (1) 9g Ultem1000 polyetherimide and 100mL of 10% sodium hydroxide aqueous solution were mixed, heated to 40°C and stirred until dissolved, then warmed to 80°C and kept for 4h; after the reaction was completed, 200mL of 20% hydrochloric acid was added, the precipitate was filtered, washed with deionized water, and dried at 130°C for 12h to obtain a polyether amic acid product;

[0108] (2) 9 g of polyether amide acid was dispersed in 45 g of water, stirred, 2 g of n-butylamine was added, heated to 40°C and kept for 4 h, the obtained solution was filtered, dried at 90°C to obtain polyether amide acid n-butylamine salt;

[0109] (3) 0.5 g of polyether amide acid n-butylamine salt was dissolved in 99.5 g of water, heated to 50°C, stirred for 2 h to obtain water-soluble polyether amide acid salt sizing agent.

[0110] In which, the content of the polyether amide acid salt is 0.5% by weight, and the content of water is 99.5% by weight, based on the total weight of the sizing agent.

[0111] And the structural formula of the prepared polyether amide acid salt is:

[0112]

[0113] In which: x:y = 26:73.

[0114] The water-soluble polyether amide acid salt sizing agent was put into a sizing tank, the unsized carbon fiber was immersed in the sizing agent and passed through the sizing tank at 1 m / min, the sizing time was 30 s, the excess sizing agent of the carbon fiber out of the tank was squeezed out, and then the sized carbon fiber was dried at 100°C, 130°C, 160°C, 180°C, 200°C, 220°C, 260°C in gradient temperature.

[0115] Comparative Example 1

[0116] Ultem 1000 polyetherimide resin was used.

[0117] In addition, it should be noted that because it cannot be dissolved in water, no sizing experiment was performed.

[0118] Comparative Example 2

[0119] The sizing agent was prepared according to the same method as Example 1, except that n-butylamine was not added.

[0120] In addition, it should be noted that because it cannot be dissolved in water, no sizing experiment was performed.

[0121] Comparative Example 3

[0122] Commercial polyimide sizing agent was used.

[0123] The water-soluble polyimide sizing agent was put into a sizing tank, the unsized carbon fiber was immersed in the sizing agent and passed through the sizing tank at 1 m / min, the sizing time was 30 s, the excess sizing agent of the carbon fiber out of the tank was squeezed out, and then the sized carbon fiber was dried at 100°C, 130°C, 160°C, 180°C, 200°C, 220°C, 260°C in gradient temperature.

[0124] Test Example 1

[0125] The solubility and thermal stability of the sizing agents prepared in the examples and comparative examples were tested, and the results are shown in Table 1 below.

[0126] Table 1

[0127] Sample name [TECHNICAL FIELD] 5％ ]] Water solubility Example 1 373℃ Dissolved Example 2 386℃ Dissolved Example 3 395℃ Dissolved Example 4 400℃ Hot water solubility Example 5 412℃ Hot water solubility Comparative Example 1 430℃ Not dissolved Comparative Example 2 416℃ Not dissolved Comparative Example 3 450℃ Dissolved in aqueous ethanol (10 vol%)

[0128] Note 1: The examples 1-5 and comparative examples 1-3 were dried at 100℃, 130℃, 160℃, 180℃, 200℃, 220℃, 260℃ gradient before the thermal gravimetric test.

[0129] Note 2: The water solubility refers to the solubility of the resin in water at 25℃, and the hot water refers to water at 80℃.

[0130] Compared with comparative example 1, the thermal stability of the water-soluble polyether amide acid salt sizing agent is slightly reduced, but its solubility in water is improved, and the modification and modification process does not reduce the molecular weight of the resin, so it still has the properties of a high molecular polymer, and therefore it can be dissolved in water to prepare a water-soluble polyether amide acid salt sizing agent. The preparation process of the sizing agent with polyetherimide as the main component is optimized, and as described in Table 2 below, the purpose of improving the interfacial strength of carbon fiber and resin and improving the performance of the composite material can be achieved.

[0131] Test Example 2

[0132] The sizing agents prepared in the examples and comparative examples were used for sizing treatment of carbon fibers, and the stiffness of the sized carbon fibers and the interlaminar shear strength of the carbon fibers and the resin were tested, and the results are shown in Table 2 below.

[0133] Table 2

[0134]

[0135] As can be seen from Table 2, compared with comparative example 3, the water-soluble polyether amide acid salt sizing agent has higher molecular chain flexibility due to the presence of amide acid groups and ether bonds in its structure, and the carbon fibers after sizing are softer and have lower stiffness, which is more conducive to subsequent processing. Compared with existing polyimide sizing agents, the water-soluble polyether amide acid salt sizing agent has better compatibility with polyetherimide resin in terms of resin structure, thereby achieving higher interfacial strength.

[0136] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A water-soluble polyether amide acid salt sizing agent, characterized by, The sizing agent comprises a polyether amide acid salt and water, wherein the polyether amide acid salt contains amide acid groups and ether bonds, and the content of the polyether amide acid salt is 0.1-50% by weight and the content of water is 50-99.9% by weight based on the total weight of the sizing agent; The polyether amide acid salt has a structure shown in formula (1): , formula (1); The molar ratio of x to y is (0-26):(73-100); R1 is selected from one or more of H, CH3, C2H5, C3H7, ph, CH2OH, CH2NH2, OH and NH2; R2 is selected from one or more of H, CH3, C2H5, C3H7, ph, CH2OH, CH2NH2, OH and NH2; R3 is selected from one or more of protonated triethylamine, diethylamine, n-propylamine, n-butylamine, cyclohexylamine, ethylenediamine, benzylamine, aniline, N-toluidine, N,N'-dimethyl aniline, diphenylamine, triphenylamine, o-toluidine, m-toluidine and p-toluidine cations; Ar is selected from one or more of , and .

2. The sizing agent according to claim 1, wherein, The content of the polyether amide acid salt is 1-10% by weight and the content of water is 90-99% by weight based on the total weight of the sizing agent.

3. A process for the preparation of the water-soluble polyether amide acid salt sizing agent according to claim 1 or 2, characterized in that, The preparation method comprises: (1) contacting polyetherimide with a first base for flexible treatment to obtain a mixed solution; then contacting the mixed solution with an acid for a first neutralization reaction, and performing filtration, washing and drying treatment to obtain polyether amide acid; wherein the polyetherimide is a polymer having imide groups and ether bonds in the molecular chain repeating unit; the first base is selected from one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide and ammonia; (2) dispersing the polyether amide acid in a solvent and then contacting it with a second base for a second neutralization reaction to obtain a polyether amide acid salt; the second base is selected from one or more of triethylamine, diethylamine, n-propylamine, n-butylamine, cyclohexylamine, ethylenediamine, benzylamine, aniline, N-toluidine, N,N'-dimethyl aniline, diphenylamine, triphenylamine, o-toluidine, m-toluidine and p-toluidine; (3) dissolving the polyether amide acid salt in water to obtain a water-soluble polyether amide acid salt sizing agent.

4. The method of claim 3, wherein the acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid and acetic acid; And / or, the amount of the first base is 1-1000 mL and the amount of the acid is 1-1000 mL relative to 1 g of the polyetherimide.

5. The method of claim 3, wherein, In step (1), the flexible treatment conditions include a temperature of 10-130°C and a time of 0.5-16 h; And / or, in step (1), the first neutralization reaction conditions include a temperature of 10-130°C and a time of 0.5-16 h.

6. The method of claim 3, wherein, The solvent is selected from one or more of water, ethanol, methanol, tetrahydrofuran and dioxane; And / or, in step (2), the second neutralization reaction conditions include a temperature of 10-130°C and a time of 0.5-16 h; and / or, the second base is used in an amount of 0.1-100 g and the polyether amide acid is used in an amount of 0.1-100 g, relative to 100 mL of the solvent.

7. The method of claim 3, wherein, In step (3), the weight ratio of the polyether amide acid salt to water is (0.1-50):(50-99.9). and / or, in step (3), the conditions under which the polyether amide acid salt is dissolved in water include a temperature of 10-80°C.

8. A water-soluble polyether amide acid salt sizing agent prepared by the preparation method of any one of claims 3-7.

9. Use of the water-soluble polyether amide acid salt sizing agent of any one of claims 1-2 and 8 for surface modification of fibers.

10. The use of claim 9, wherein the fibers comprise carbon fibers and / or graphite fibers. and / or, the fibers are used in an amount of 5-5000 g, relative to 100 mL of the sizing agent.

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