Vinyl resin sizing agent, its preparation method and application

Abstract

The present application relates to the technical field of sizing agent preparation, and discloses a vinyl resin sizing agent, a preparation method and application thereof. The present application utilizes the reaction between the thiol group in 3-mercaptopropionic acid and the epoxy group in epoxy resin to generate a sulfide bond, causes the ring opening of the epoxy group, and introduces an unsaturated double bond in the epoxy resin through a series of chemical modification treatments. The unsaturated double bond can chemically crosslink with the double bond in the molecular chain of the vinyl ester resin or unsaturated polyester resin during the curing process, thereby forming a chemical bond connection between the carbon fiber and the resin matrix, and significantly improving the interfacial bonding strength of the composite material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sizing agent preparation, in particular to a preparation method and application of a vinyl resin sizing agent. BACKGROUND

[0002] Carbon fiber is a typical representative of high-performance fibers, which has the characteristics of low density, high temperature resistance, corrosion resistance, fatigue resistance, and good damping, shock absorption, and noise reduction, especially high specific strength and high specific modulus. Carbon fiber reinforced composite material (CFRP) is a composite material made of carbon fiber or fiber fabric as reinforcement and resin, ceramic, asphalt, etc. as matrix. Carbon fiber can be combined with vinyl resin to prepare carbon fiber reinforced vinyl resin composite material. Vinyl resin is internationally recognized as a highly corrosion-resistant resin, commonly used for corrosion-resistant lining, crack filling materials or combined with other reinforcing materials, which can produce high-strength and fatigue-resistant products. Carbon fiber reinforced vinyl resin composite material is applied to ship materials due to its advantages of high corrosion resistance, light weight and high strength, and can resist seawater corrosion.

[0003] The polyacrylonitrile-based carbon fiber in the prior art is basically sized with an epoxy sizing agent, which has good interfacial properties and mechanical properties for composite materials prepared with an epoxy resin matrix. However, for vinyl ester resin, vinyl ester resin undergoes free radical polymerization during curing, and due to the difference in polymerization mechanism and structure, the interfacial properties and mechanical properties of the prepared composite material are significantly reduced.

[0004] Therefore, it is necessary to prepare a water-soluble sizing agent suitable for a vinyl ester resin matrix to improve the interfacial properties of polyacrylonitrile-based carbon fiber and vinyl ester resin, and further improve the mechanical properties of vinyl resin composite material. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a vinyl resin sizing agent and its preparation method and application, which improve the interfacial properties and mechanical properties of the composite material.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0007] A preparation method of a vinyl resin sizing agent, comprising the following steps:

[0008] S1. Mix 1-4 parts of epoxy resin with 100-150 parts of anhydrous ethanol by mass fraction, mechanically stir and condense reflux at 60-80 DEG C for 1-2h;

[0009] S2. Add 1-5 parts of 3-mercaptopropionic acid and 1-2 parts of potassium carbonate to the system treated by step S1 by mass fraction, continue to mechanically stir and condense reflux at 60-80 DEG C for 8-9h;

[0010] S3. 1-5 parts of thionyl chloride are added to the system treated in step S2 by mass parts, and after mechanical stirring at 0-20 DEG C for 1-2h, 2-3 parts of triethylamine are added and the temperature is raised to 40-50 DEG C for stirring for 0.5-1h to prepare a sizing agent main body;

[0011] S4. The sizing agent main body is subjected to solvent removal of anhydrous ethanol at 80-90 DEG C in a rotary evaporating dish to obtain a modified epoxy resin;

[0012] S5. 6-8 parts of the modified epoxy resin, 2-4 parts of a softener, and 0.1-0.3 parts of a penetrating agent are mixed by mass parts to prepare a sizing agent main polymer;

[0013] S6. 0.25-1 parts of the sizing agent main polymer and 90-110 parts of water are mixed by mass parts to prepare a vinyl resin sizing agent.

[0014] Preferably, in S1, the epoxy resin is a tetrafunctional glycidyl amine type high-temperature resistant epoxy resin, and specifically includes MF-4101H.

[0015] Preferably, in S1 and S2, the mass ratio of the epoxy resin to the 3-mercaptopropionic acid is (4-1):1.

[0016] Preferably, in S2 and S3, the mass ratio of the 3-mercaptopropionic acid to the thionyl chloride is (0.9-0.2):1.

[0017] Preferably, in S5, the softener is a non-ionic softener, and includes DEG-502.

[0018] Preferably, in S5, the penetrating agent is a non-ionic penetrating agent, and includes one of JFC-2 and JFC-2G.

[0019] A vinyl resin sizing agent prepared by the preparation method of any one of the above.

[0020] Application of a vinyl resin sizing agent in sizing of carbon fibers.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] 1. The present application utilizes the reaction of the thiol group in 3-mercaptopropionic acid with the epoxy group in epoxy resin to form a thioether bond, causing the epoxy group to open ring, and through a series of chemical modification processes, introducing unsaturated double bonds and hydroxyl functional groups in the epoxy resin, the unsaturated double bonds can chemically crosslink with the double bonds in the molecular chain of vinyl ester resin or unsaturated polyester resin during the curing process, and the hydroxyl groups can form hydrogen bonds with the polar groups such as hydroxyl groups in the molecular chain of vinyl ester resin or unsaturated polyester resin, thereby forming chemical bonds between carbon fibers and resin matrix, significantly improving the interfacial bonding strength of the composite material;

[0023] 2. The carbon fiber treated with the vinyl resin sizing agent prepared by the present application can be infiltrated by polyester resins (such as unsaturated polyester and vinyl ester resin) when used to prepare carbon fiber composites, thereby greatly reducing the molding time of carbon fiber composites, reducing the fixed asset investment of carbon fiber composite molding equipment, and realizing low-cost and rapid molding of carbon fiber composites;

[0024] 3. Compounding the synthesized sizing agent main body with a softener and a penetrant can improve the softness of polyacrylonitrile-based carbon fiber after sizing. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the description of the embodiments of the present application will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the contents of the embodiments of the present application and these drawings.

[0026] Figure 1 is the preparation flow chart of the vinyl resin sizing agent prepared by the present application;

[0027] Figure 2 is the preparation route and structure diagram of the vinyl resin sizing agent prepared by the present application. DETAILED DESCRIPTION

[0028] In order to facilitate the understanding of the present application, the present application will be described more fully below. The present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive. Unless otherwise defined, all technical and scientific terms used in the present application belong to the technical field of the present application.

[0029] The present application will be further described below through specific embodiments.

[0030] Example 1:

[0031] A preparation method of a vinyl resin sizing agent

[0032] S1. Add 0.4225 g of epoxy resin MF-4101H and 9.48 g of anhydrous ethanol (in other embodiments, the mass of anhydrous ethanol can be set to 12.5 g or 15 g) into a three-necked flask, mix, mechanically stir and reflux condense at 80℃ for 1 h; of course, in other embodiments, it can be mechanically stirred and reflux condensed at 60℃ for 2 h or mechanically stirred and reflux condensed at 70℃ for 1.5 h, with the actual situation being determined accordingly;

[0033] S2. Add 0.2123 g of 3-mercaptopropionic acid and 0.1380 g of potassium carbonate (in other embodiments, the mass of potassium carbonate can be set to 0.1 g or 0.2 g) to the system treated in step S1 through a separatory funnel, continue to mechanically stir and reflux condense at 80℃ for 8 h; of course, in other embodiments, it can be continued to mechanically stir and reflux condense at 60℃ for 9 h or mechanically stirred and reflux condensed at 70℃ for 8.5 h, with the actual situation being determined accordingly;

[0034] S3. Add 0.2855 g of thionyl chloride to the system treated in step S2, mechanically stir at 10℃ for 1 h, then add 0.2024 g of triethylamine (in other embodiments, the mass of triethylamine can be set to 0.25 g or 0.3 g) and stir at 40℃ for 1 h to prepare a sizing agent main body; of course, in other embodiments, it can be stirred at 50℃ for 0.5 h or stirred at 45℃ for 0.75 h, with the actual situation being determined accordingly;

[0035] S4. Remove the solvent anhydrous ethanol from the sizing agent main body at 80℃ (in other embodiments, it can be reacted at 90℃ or 85℃) in a rotary evaporator to obtain a modified epoxy resin;

[0036] S5. Mix 7 parts of the modified epoxy resin, 3 parts of DEG-502 and 0.2 parts of JFC-2 by mass fraction to prepare a sizing agent main polymer;

[0037] S6. Mix 0.25 parts of the sizing agent main polymer and 100 parts of water (in other embodiments, the water can be set to 90 parts or 110 parts) by mass fraction to prepare a vinyl resin sizing agent, and the preparation route and structural diagram of the vinyl resin sizing agent are as shown in Figure 2 .

[0038] Example 2: Example 2 is only different from Example 1 in that the sizing agent main polymer in S6 is 0.5 parts in Example 2.

[0039] Example 3: Example 3 differs from Example 1 only in that in Example 3, the sizing agent main polymer in S6 is 0.75 parts.

[0040] Example 4: Example 4 differs from Example 1 only in that in Example 4, the sizing agent main polymer in S6 is 1 part.

[0041] Example 5: Example 5 differs from Example 1 only in that in Example 5, epoxy resin MF-4101H: 0.4225 g, 3-mercaptopropionic acid: 0.3184 g, sulfurous chloride: 0.3926 g; the sizing agent main polymer in S6 is 0.5 parts.

[0042] Example 6: Example 6 differs from Example 1 only in that in Example 6, epoxy resin MF-4101H: 0.4225 g, 3-mercaptopropionic acid: 0.4246 g, sulfurous chloride: 0.5234 g; the sizing agent main polymer in S6 is 0.5 parts.

[0043] Example 7: Example 7 differs from Example 1 only in that in Example 7, epoxy resin MF-4101H: 0.4225 g, 3-mercaptopropionic acid: 0.1061 g, sulfurous chloride: 0.1309 g; the sizing agent main polymer in S6 is 0.5 parts.

[0044] Example 8: Example 8 differs from Example 1 only in that in Example 8, epoxy resin MF-4101H: 0.4225 g, 3-mercaptopropionic acid: 0.4246 g, sulfurous chloride: 0.4758 g; the sizing agent main polymer compounding ratio in S5 is modified epoxy resin: DEG-502: JFC-2 = 6:4:0.3; the sizing agent main polymer in S6 is 0.5 parts.

[0045] Example 9: Example 9 differs from Example 1 only in that in Example 9, epoxy resin MF-4101H: 0.4225 g, 3-mercaptopropionic acid: 0.4246 g, sulfurous chloride: 0.5234 g; the sizing agent main polymer compounding ratio in S5 is modified epoxy resin: DEG-502: JFC-2 = 8:2:0.1; the sizing agent main polymer in S6 is 0.5 parts.

[0046] Example 10: Example 10 is only different from Example 1 in that in Example 9, epoxy resin MF-4101H: 0.4225 g, 3-mercaptopropionic acid: 0.1061 g, sulfurous chloride: 0.5234 g; the sizing agent main polymer complex ratio in S5 is modified epoxy resin: DEG-502: JFC-2G = 8:2:0.2; the sizing agent main polymer in S6 is 0.5 parts.

[0047] To further illustrate the key of the patent, a comparative example is added for illustration.

[0048] Comparative Example 1: 12K polyacrylonitrile carbon fiber sized with commercially available epoxy type sizing agent. The manufacturer is Zhongfengshenying Carbon Fiber Co., Ltd., and the model is SYT49S.

[0049] Performance test:

[0050] The stiffening degree, sizing rate, contact angle, interlaminar shear strength, and water solubility of the sized carbon fibers of Examples 1-10 and Comparative Example 1 were tested respectively, and the test methods are as follows:

[0051] Water solubility: The sizing agents prepared under different conditions were prepared into sizing agents with the same solid content and placed in centrifuge tubes at room temperature for 30 days to see if there was any precipitation.

[0052] Stiffness: Take 50 cm of carbon fiber sized under different conditions, hang the middle of the carbon fiber on a stainless steel hook, then naturally hang for 30 s, measure the transverse distance between the two ends of the carbon fiber bundle 10 cm below the stainless steel hook, and record it as the stiffness of the carbon fiber.

[0053] Contact angle: First, the vinyl ester resin and the accelerator, curing agent are mixed according to a certain proportion. Take the single fiber of the sized carbon fiber under different conditions and fix it on the sample table. Dip a small amount of vinyl ester resin with a large needle and quickly draw it along the surface of the fiber single fiber. Curing at room temperature for 12 h. Select a small ball of resin with a diameter of 0.15-0.2 mm to test the static contact angle of the sample.

[0054] Interlaminar shear strength: The carbon fibers sized under different conditions were woven into 4 cm x 8 cm unidirectional cloth, and vinyl ester resin was coated between each layer of unidirectional cloth, with a fiber volume fraction of 60% during the process. The prepared sample was hot pressed at 160℃ under 2MPa for 2h, and then hot pressed at 180℃ under 2MPa for another 2h. The interlaminar shear strength of the sample was tested according to GB / T30969-2014.

[0055] The test results are shown in Table 1.

[0056] Table 1: Performance test table

[0057] Stability Stiffness (cm) Contact angle (°) Interlayer shear strength (MPa) Example 1 No precipitation, good uniformity 5.9 65.00 52.903 Example 2 No precipitation, good uniformity 8.0 64.00 56.007 Example 3 No precipitation, good uniformity 11.1 59.75 53.103 Example 4 No precipitation, good uniformity 13.2 56.50 59.747 Example 5 No precipitation, good uniformity 7.6 54.25 55.092 Example 6 No precipitation, good uniformity 8.0 53.75 55.299 Example 7 No precipitation, good uniformity 10.7 59.00 50.158 Example 8 No precipitation, good uniformity 7.1 64.25 53.918 Example 9 No precipitation, good uniformity 8.5 61.50 51.013 Example 10 No precipitation, good uniformity 9.2 60.25 52.457 Comparative Example 1 / 7.7 69.25 39.121

[0058] Comparing examples 1-10 with comparative example 1, the contact angle of examples is smaller and the interlaminar shear strength is larger, which shows that the carbon fiber after being sized by the vinyl resin sizing agent prepared by the application has better interface bonding with vinyl ester resin, and the interlaminar shear strength of the carbon fiber sized by the vinyl resin sizing agent has reached the performance requirement (≥50MPa) of the uniaxial interlaminar shear strength of the carbon fiber warp fabric for ships.

[0059] The stiffness of the carbon fiber is greatly affected by the concentration of the aqueous solution of the sizing agent, which is mainly due to the fact that the benzene ring structure in the modified epoxy resin is relatively rigid, and increasing the compounding ratio of DEG-502 during the compounding of the main polymer of the sizing agent helps to reduce the influence of the relatively large stiffness of the sized carbon fiber.

[0060] As described above, it is proved that the application generates a sulfide bond by using the thiol group in 3-mercaptopropionic acid to react with the epoxy group in the epoxy resin, opens the ring of the epoxy group, and introduces unsaturated double bonds and hydroxyl functional groups into the epoxy resin through a series of chemical modification processes. The unsaturated double bonds and the double bonds in the molecular chain of the vinyl ester resin or unsaturated polyester resin chemically crosslink during the curing process, the hydroxyl groups and the polar groups such as hydroxyl groups in the molecular chain of the vinyl ester resin or unsaturated polyester resin form hydrogen bonds, and then chemical bonds are formed between the carbon fiber and the resin matrix, which significantly improves the interface bonding strength of the composite material, and successfully prepares a new carbon fiber sizing agent, which has obvious application value due to its simple compounding and low requirement for production conditions.

[0061] The above are only the preferred embodiments of the application and the technical principles applied, and those skilled in the art will understand that the application is not limited to the specific embodiments described herein, and various obvious changes, re-adjustments and substitutions can be made by those skilled in the art without departing from the scope of the application. Therefore, although the application has been described in more detail through the above examples, the application is not limited to the above examples, and more other equivalent embodiments can be included without departing from the concept of the application, and the scope of the application is determined by the scope of the appended claims.

Claims

1. A method for preparing a vinyl resin sizing agent, characterized in that, Includes the following steps: S1. Mix 1-4 parts by weight of epoxy resin with 100-150 parts by weight of anhydrous ethanol, mechanically stir at 60-80℃ and reflux for 1-2 hours. S2. Add 1-5 parts by weight of 3-mercaptopropionic acid and 1-2 parts by weight of potassium carbonate to the system treated in step S1, and continue mechanical stirring and reflux at 60-80℃ for 8-9 hours. S3. Add 1-5 parts by weight of thionyl chloride to the system treated in step S2, mechanically stir at 0-20℃ for 1-2 hours, add 2-3 parts of triethylamine and heat to 40-50℃ and stir for 0.5-1 hours to obtain the sizing agent body. S4. Remove the solvent anhydrous ethanol from the sizing agent in a rotary evaporating dish at 80-90°C to obtain modified epoxy resin; S5. Mix 6-8 parts of the modified epoxy resin, 2-4 parts of the softener, and 0.1-0.3 parts of the penetrant by weight to obtain the main polymer of the sizing agent; S6. Mix 0.25-1 parts by weight of the main polymer of the sizing agent and 90-110 parts by weight of water to obtain a vinyl resin sizing agent.

2. The method for preparing the vinyl resin sizing agent according to claim 1, characterized in that, In S1, the epoxy resin is a tetrafunctional glycidyl amine-based high-temperature resistant epoxy resin, specifically including MF-4101H.

3. The method for preparing the vinyl resin sizing agent according to claim 1, characterized in that, In S1 and S2, the mass ratio of the epoxy resin to the 3-mercaptopropionic acid is (4-1):

1.

4. The method for preparing the vinyl resin sizing agent according to claim 1, characterized in that, In S2 and S3, the mass ratio of 3-mercaptopropionic acid to thionyl chloride is (0.9-0.2):

1.

5. The method for preparing the vinyl resin sizing agent according to claim 1, characterized in that, In S5, the fabric softener is a nonionic fabric softener, including DEG-502.

6. The method for preparing the vinyl resin sizing agent according to claim 1, characterized in that, In S5, the penetrant is a nonionic penetrant, including one of JFC-2 and JFC-2G.

7. A vinyl resin sizing agent, characterized in that, It is prepared by the preparation method according to any one of claims 1-6.

8. The application of the vinyl resin sizing agent according to claim 7 in carbon fiber sizing.

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