Amphiphilic sizing agent suitable for glass fiber / resin composite material

Abstract

The invention discloses an amphiphilic sizing agent suitable for a glass fiber / resin composite material, which is prepared by polymerizing glycidyl methacrylate and methacrylic acid ethyl trimethyl ammonium chloride by a reversible addition-fragmentation chain transfer polymerization method to form glycidyl ester-ethyl trimethyl ammonium chloride; and introducing dopamine methacrylamide by using a free radical polymerization technology to obtain the amphiphilic sizing agent. The amphiphilic sizing agent can be applied to the surface of the glass fiber without being filled with a plasticizer, a coupling agent, an inhibitor and the like, the coating performance and the binding performance of a product can be adjusted by changing the proportion of structural units, and the amphiphilic sizing agent can form a covalent binding effect with hydroxyl on the glass fiber through epoxy; positive charges and negative charges on the surface of the glass fiber can form electrostatic interaction combination, and dopamine groups and groups on the resin can form powerful hydrogen-bond interaction, so that efficient load transfer is realized.

Description

Technical Field

[0001] This invention relates to the field of one-dimensional material preparation technology, and more particularly to an amphiphilic sizing agent suitable for glass fiber / resin composite materials. Background Technology

[0002] Glass fiber (GF) reinforced thermoplastic resin composites are widely used in industries such as automotive, aerospace, and sporting goods due to their excellent processability and cost-effectiveness. However, the interfacial compatibility between glass fiber and the matrix has always been one of the key challenges in improving the performance of these materials. To overcome these obstacles, researchers have tried various methods to enhance the adhesion between GF and resin. Among them, the application of appropriate sizing agents is considered an effective strategy. Given the urgent need for high mechanical properties in industrial applications of glass fiber / resin composites, the interfacial role of sizing agents in reinforcing glass fiber / resin composites needs to be improved. Summary of the Invention

[0003] To address the aforementioned shortcomings, this invention proposes an amphiphilic sizing agent suitable for glass fiber / resin composite materials, which can form a strong interfacial adhesion between glass fiber and resin, thus facilitating efficient load transfer.

[0004] To achieve the above objectives, the present invention provides the following technical solution: an amphiphilic sizing agent suitable for glass fiber / resin composite materials, wherein the amphiphilic sizing agent is produced by polymerizing glycidyl methacrylate and ethyltrimethylammonium methacrylate via a reversible addition-fragmentation chain transfer polymerization method, and then introducing dopamine methacrylamide using free radical polymerization technology, the general structural formula of which is: Where 2 < x < 84, 1 < y < 42, 1 < z < 34.

[0005] As an improvement, the preparation of this amphiphilic sizing agent includes the following steps: S1: Dopamine hydrochloride and tetrahydrofuran solution containing methacrylic anhydride are subjected to an amination reaction under alkaline conditions. Sodium hydroxide is then added to adjust the pH to alkaline. The reaction is carried out at low temperature under nitrogen protection. After the reaction is completed, dopamine methacrylamide is obtained by separation and purification with hydrochloric acid, ethyl acetate, anhydrous sodium sulfate or anhydrous magnesium sulfate, and n-pentane. S2: Glycidyl methacrylate and ethyltrimethylammonium methacrylate are subjected to a reversible addition-fragmentation chain transfer polymerization method in the presence of trithiocarbonate and ammonium persulfate catalysts to obtain glycidyl methacrylate-ethyltrimethylammonium chloride. S3: Glycidyl ester-ethyltrimethylammonium chloride and dopamine methacrylamide are subjected to free radical polymerization in the presence of cumene hydroperoxide in a certain proportion to obtain an amphiphilic sizing agent.

[0006] As an improvement, the amount of dopamine hydrochloride in step S1 is 0.5-1.5 parts by weight, and the amount of methacrylic anhydride is 1-2 parts by weight.

[0007] As an improvement, step S1 specifically includes the following steps: S1.1: Dissolve 10-30g sodium borate and 3-13g sodium bicarbonate in 170-230 mL of deionized water, wherein the reaction concentration of sodium borate is 5%-20% and the reaction concentration of sodium bicarbonate is 1%-10%; after stirring with nitrogen gas, add 5-15g dopamine hydrochloride to the solution and dropwise add 30-50mL of tetrahydrofuran solution containing 6-12mL of methacrylic anhydride; S1.2: By adding sodium hydroxide, the pH of the solution is maintained at 8-10. After reacting at 0-8℃ for 20-28h under nitrogen protection, 80-120 mL of ethyl acetate is added to the solution while stirring slowly to separate the organic and inorganic phases. S1.3: Adjust the pH of the solution to below 2 by adding hydrochloric acid, separate the organic layer using a separation funnel, wash the organic layer several times with 70-110 mL of ethyl acetate, and then add 2-8 g of anhydrous magnesium sulfate under vacuum filtration to remove residual water from the organic layer. S1.4: Add 20-80 mL of n-pentane to precipitate dopamine methacrylamide and store the product in a refrigerator.

[0008] As an improvement, in step S2, glycidyl methacrylate is 1-3 parts by weight, with a reaction concentration of 10%-20%; ethyltrimethylammonium methacrylate is 0.5-1.5 parts by weight, with a reaction concentration of 5%-10%; trithiocarbonate is 0.005-0.02 parts by weight; and ammonium persulfate is 0.002-0.01 parts by weight.

[0009] As an improvement, step S2 specifically includes: mixing 5-10g glycidyl methacrylate, 2-6g ethyltrimethylammonium chloride methacrylate, 0.1-0.2g trithiocarbonate, 0.01-0.07g ammonium persulfate and 30-70mL of water in a three-necked flask, and polymerizing it with ammonium persulfate starter at a temperature of 60-80°C under nitrogen protection; the mixture is reacted with vigorous stirring for 7-12 hours.

[0010] As an improvement, in step S3, the glycidyl ester-ethyltrimethylammonium chloride and dopamine methacrylamide are in an equivalent ratio of 3:1, and the amount of cumene hydroperoxide is 0.2-0.5 parts by weight.

[0011] As an improvement, step S3 specifically includes: mixing 0.3-1.1g of dopamine methacrylamide with 0.9-3.3g of glycidyl ester-ethyltrimethylammonium chloride solution, and reacting at room temperature under nitrogen protection and with the action of cumene hydroperoxide for 7-11 hours.

[0012] As an improvement, it also includes S4: glass fiber is immersed in a prepared amphiphilic sizing agent with a concentration of 10-20% and dried in a vacuum oven to obtain a new coating; Step S4 specifically includes the following steps: S4.1: Ultrasonically wash the glass fiber for 2-4 hours to remove the original surface coating on the glass fiber; S4.2: After drying in a vacuum oven at 90-110℃ for 10-14 hours, soak in an aqueous solution containing 8-12% amphiphilic sizing agent, and then dry in a vacuum oven for 10-14 hours to form a new coating on the glass fiber surface.

[0013] As an improvement, the following steps are included to obtain glass fiber reinforced nylon 6 composite material after forming a new coating on the glass fiber surface: S5.1: Spread 50-70g of nylon granules evenly into a mold with the same size as the glass fiber, and preheat at 220-280℃ without pressure for 5-10 minutes; S5.2: Hot press at 2-4 MPa for 2-5 min, hot press at 10-15 MPa for 8-10 min, and immediately after removal, cold press at 10-15 MPa on another hot press. S5.3: After the temperature of the mold is reduced to room temperature, the mold is demolded to obtain a nylon 6 film. Several pieces of modified glass fiber and nylon 6 film are alternately stacked on a flat vulcanizing machine and hot-pressed. After demolding, the glass fiber reinforced nylon 6 composite material is obtained.

[0014] Compared with the prior art, the advantages of the present invention are as follows: (1) An innovative amphiphilic sizing agent was developed. Glycidyl methacrylate and ethyltrimethylammonium methacrylate were polymerized by reversible addition-fragmentation chain transfer polymerization. Then, dopamine methacrylamide was introduced by free radical polymerization. In this unique design, the cationic component in the sizing agent can effectively prevent the oxidation of dopamine, thereby ensuring the stability and functionality of the sizing agent. The amphiphilic sizing agent can form a strong interfacial adhesion between glass fiber and resin, which helps to achieve efficient load transfer and ultimately significantly improves the mechanical properties of glass fiber / resin composites. (2) The amphiphilic sizing agent provided by the present invention has a simple formulation and can be applied to the surface of glass fiber without the need for plasticizers, coupling agents and inhibitors. The coating performance and bonding performance of the product can be adjusted by changing the ratio of structural units. The amphiphilic sizing agent can form a covalent bond with the hydroxyl groups on the glass fiber through epoxy, and the positive charge it carries can also form an electrostatic bond with the negative charge on the surface of the glass fiber. The dopamine group can form a strong hydrogen bond with the group on the resin, which helps to achieve efficient load transfer.

[0015] (3) The amphiphilic sizing agent is easy to dissolve in water and can be evenly coated on the surface of glass fiber. The wettability of the glass fiber in the resin is improved after sizing, making the composite material easier to form during processing and reducing processing difficulty and cost. Attached Figure Description

[0016] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: Figure 1 This is a general structural formula for an amphiphilic sizing agent suitable for glass fiber / resin composite materials; Figure 2 This is a schematic diagram of the reaction process of glycidyl ester-ethyltrimethylammonium chloride; Figure 3 This is a schematic diagram of the reaction process of an amphiphilic sizing agent. Figure 4 This is a schematic diagram of the interface interaction in glass fiber / resin composite materials. Detailed Implementation

[0017] Example 1 S1.1: Dissolve 20g sodium borate and 8g sodium bicarbonate in 200 mL of deionized water, stir with nitrogen gas, add 10g dopamine hydrochloride to the solution, and add dropwise 40mL tetrahydrofuran solution containing 9.4mL methacrylic anhydride. S1.2: The pH of the solution was maintained at 8-10 by adding sodium hydroxide. After reacting at 4°C for 24 hours under nitrogen protection, 100 mL of ethyl acetate was added to the solution while stirring slowly to separate the organic and inorganic phases. S1.3: Adjust the pH of the solution to below 2 by adding hydrochloric acid, separate the organic layer using a separation funnel, wash the organic layer three times with 90 mL of ethyl acetate, and then add 5 g of anhydrous magnesium sulfate under vacuum filtration to remove residual water from the organic layer. S1.4: Add 50 mL of n-pentane to precipitate dopamine methacrylamide, and store the product in a refrigerator at 4°C; S2: 7.52 g glycidyl methacrylate, 4.42 g ethyltrimethylammonium chloride methacrylate, 0.136 g trithiocarbonate, 0.044 g ammonium persulfate, and 50 mL of water were mixed in a three-necked flask and polymerized with ammonium persulfate as a starter at 70°C under nitrogen protection. The mixture was reacted with vigorous stirring for 9 h. S3: Mix 0.72g of dopamine methacrylamide with 2.19g of polymethacrylic acid (glycidyl ethyltrimethylammonium chloride) solution and react at room temperature under nitrogen protection and with the action of cumene hydroperoxide for 9 hours; S4.1: Ultrasonically wash 25 cm × 25 cm glass fibers for 3 hours to remove the original surface coating on the glass fibers; S4.2: After drying in a vacuum oven at 100℃ for 12 hours, soak in an aqueous solution containing 10% amphiphilic sizing agent, and then dry in a vacuum oven for 12 hours to form a new coating on the glass fiber surface; S5.1: Spread 60g of nylon granules evenly into a mold with dimensions of 25 cm × 25 cm, and preheat at 250℃ without pressure for 8 minutes; S5.2: Hot press at 3 MPa for 3.5 min, hot press at 13 MPa for 9 min, and immediately after removal, cold press at 13 MPa on another hot press. S5.3: After the temperature of the mold is reduced to room temperature, the mold is demolded to obtain a nylon 6 film. Seven pieces of modified glass fiber and nine pieces of nylon 6 film are alternately stacked on a flat vulcanizing machine and hot-pressed. After demolding, the glass fiber reinforced nylon 6 composite material is obtained.

[0018] Interlaminar shear strength (ILSS) was used to characterize the bond strength between layers of carbon fiber composite laminates. The test was conducted according to ASTM D2344 standard, with specimen dimensions of 20 mm × 10 mm × 2 mm, a test span of 10 mm, and an indenter loading speed of 1 mm / min.

[0019] The interlaminar shear strength of the glass fiber reinforced nylon 6 composite material obtained in Example 1 is 35 MPa.

[0020] Example 2 S4.2: After drying in a vacuum oven at 100℃ for 12 hours, the fiberglass is immersed in an aqueous solution containing 20% ​​amphiphilic sizing agent and then dried in a vacuum oven for 12 hours to form a new coating on the fiberglass surface. The other experimental procedures are the same as in Example 1.

[0021] The interlaminar shear strength of the glass fiber reinforced nylon 6 composite material obtained in Example 2 was 31 MPa, which was lower than that in Example 1. This was because the high concentration of amphiphilic sizing agent wrapped the reaction binding sites within the molecular chain, preventing good contact with the glass fiber and resin.

[0022] Example 3 S2: 7.52 g glycidyl methacrylate, 4.42 g ethyltrimethylammonium chloride methacrylate, 0.136 g trithiocarbonate, 0.044 g ammonium persulfate, and 50 mL of water were mixed in a three-necked flask and polymerized with ammonium persulfate as a starter at 70°C under nitrogen protection. The mixture was reacted with vigorous stirring for 9 h. S3: Mix 1.44g of dopamine methacrylamide with 2.19g of polymethacrylic acid (glycidyl ethyltrimethylammonium chloride) solution and react at room temperature under nitrogen protection and with the action of cumene hydroperoxide for 9 hours; The other experimental procedures are the same as in Example 1.

[0023] The interlaminar shear strength of the composite material obtained in Example 3 was 25 MPa. The low strength was due to the large molecular weight, which made bonding difficult and flowability poor, resulting in an insignificant reinforcing effect.

[0024] Comparative Example The purchased 25 cm × 25 cm glass fibers were ultrasonically washed for 3 hours to remove the original surface coating. They were then dried in a vacuum oven at 100°C for 12 hours, soaked in a pure aqueous solution, and then dried in a vacuum oven for 12 hours. Subsequently, they were laminated with nylon using the same steps as in Examples 5.1, 5.2, and 5.3.

[0025] The interlaminar shear strength of the composite material obtained in the comparative example was 20 MPa.

[0026] The interlayer shear strength of Example 1 after modification was 35 MPa, which is 75% higher than the 20 MPa of the control example. This is because the amphiphilic sizing agent of Example 1 has a moderate molecular weight and an appropriate ratio of hydrophilic to hydrophobic properties, which can combine well with glass fiber and resin, achieving efficient load transfer and ultimately significantly improving the mechanical properties of the glass fiber / resin composite material.

[0027] Amphiphilic sizing agent structure as follows Figure 1 As shown, in the structural formula, 2 < x < 84, 1 < y < 42, and 1 < z < 34. Figure 2 This is a schematic diagram of the reaction process of polymethacrylic acid (glycidyl ester-ethyltrimethylammonium chloride); Figure 3 , Figure 4These are schematic diagrams of the reaction process of the amphiphilic sizing agent and the interface interaction of the glass fiber / resin composite material, respectively.

[0028] The above description only illustrates the preferred embodiments of the present invention and should not be construed as limiting the scope of the claims. The present invention is not limited to the above embodiments, and variations in its specific structure are permitted. All modifications made within the scope of the independent claims of this invention are also within the scope of protection of this invention.

Claims

1. An amphiphilic sizing agent suitable for glass fiber / resin composite materials, characterized in that: Glycidyl methacrylate and ethyl trimethyl ammonium chloride of methacrylate are polymerized by a reversible addition-fragmentation chain transfer polymerization method to form glycidyl methacrylate-ethyl trimethyl ammonium chloride, and then dopamine methacrylamide is introduced by free radical polymerization technology to obtain the amphiphilic sizing agent, and its general structural formula is: Among them, 2<x<84, 1<y<42, 1<z<34.

2. The amphiphilic sizing agent suitable for glass fiber / resin composite materials according to claim 1, characterized in that: The preparation of the amphiphilic sizing agent comprises the following steps: S1: performing an amination reaction of dopamine hydrochloride and a tetrahydrofuran solution containing methacrylic anhydride under alkaline conditions, subsequently adding sodium hydroxide to adjust the pH to alkaline, and performing a low-temperature reaction under nitrogen protection. After the reaction is completed, the dopamine methacrylamide is separated and purified by hydrochloric acid, ethyl acetate, anhydrous sodium sulfate or anhydrous magnesium sulfate, and n-pentane to obtain dopamine methacrylamide; S2: glycidyl methacrylate and ethyl trimethyl ammonium methacrylate are subjected to a reversible addition-fragmentation chain transfer polymerization method in the presence of a catalyst trithiocarbonate and ammonium persulfate to obtain glycidyl methacrylate-ethyl trimethyl ammonium chloride; S3: Glycidyl ester-ethyltrimethylammonium chloride and dopamine methacrylamide are subjected to free radical polymerization in proportion under the action of cumene hydroperoxide to obtain an amphiphilic sizing agent.

3. The amphiphilic sizing agent suitable for glass fiber / resin composite materials according to claim 2, characterized in that: The dopamine hydrochloride in step S1 is 0.5-1.5 parts by weight, and the methacrylic anhydride is 1-2 parts by weight.

4. The amphiphilic sizing agent suitable for glass fiber / resin composite materials according to claim 2, characterized in that: The step S1 specifically includes the following steps: S1.1: Dissolve 10-30g of sodium borate and 3-13g of sodium bicarbonate in 170-230mL of deionized water, wherein the reaction concentration of the sodium borate is 5%-20%, and the reaction concentration of the sodium bicarbonate is 1%-10%; then, after stirring with nitrogen, add 5-15g of dopamine hydrochloride to the solution, and dropwise add 30-50mL of tetrahydrofuran solution containing 6-12mL of methacrylic anhydride; S1.2: by adding sodium hydroxide, the pH value of the solution is maintained at 8-10, and after reacting at 0-8°C for 20-28 hours under nitrogen protection, 80-120 mL of ethyl acetate is added to the solution while slowly stirring to separate the organic phase and the inorganic phase; S1.3: Adjust the pH value of the solution to less than 2 by adding hydrochloric acid dropwise, separate the organic layer using a separatory funnel, wash the organic layer several times with 70-110 mL of ethyl acetate, and then add 2-8 g of anhydrous magnesium sulfate under vacuum filtration to remove residual water in the organic layer; S1.4: Add 20-80 mL of n-pentane to precipitate dopamine methacrylamide and store the product in a refrigerator.

5. The amphiphilic sizing agent suitable for glass fiber / resin composite materials according to claim 2, characterized in that: The glycidyl methacrylate in step S2 is 1-3 parts by weight, and its reaction concentration is 10%-20%, the ethyl trimethyl ammonium chloride of methacrylate is 0.5-1.5 parts by weight, and its reaction concentration is 5%-10%, the trithiocarbonate is 0.005-0.02 parts by weight, and the ammonium persulfate is 0.002-0.01 parts by weight.

6. The amphiphilic sizing agent suitable for glass fiber / resin composite materials according to claim 2, characterized in that: The step S2 specifically comprises: mixing 5-10 g of glycidyl methacrylate, 2-6 g of ethyl trimethyl ammonium chloride of methacrylate, 0.1-0.2 g of trithiocarbonate, 0.01-0.07 g of ammonium persulfate and 30-70 mL of water in a three-necked bottle, and polymerizing with ammonium persulfate as a starter at 60-80° C. under nitrogen protection; reacting the mixture under strong stirring for 7-12 hours.

7. The amphiphilic sizing agent suitable for glass fiber / resin composite materials according to claim 2, characterized in that: The equivalent ratio of glycidyl ester-ethyltrimethylammonium chloride to dopamine methacrylamide in step S3 is 3:1, and the amount of cumene hydroperoxide is 0.2-0.5 parts by weight.

8. The amphiphilic sizing agent suitable for glass fiber / resin composite materials according to claim 2, characterized in that: The step S3 specifically comprises: mixing 0.3-1.1 g of dopamine methacrylamide with 0.9-3.3 g of glycidyl ester-ethyltrimethylammonium chloride solution, and reacting for 7-11 hours at room temperature under nitrogen protection and under the action of cumene hydroperoxide.

9. The amphiphilic sizing agent suitable for glass fiber / resin composite materials according to claim 2, characterized in that: The process also includes S4: immersing the glass fiber in the prepared amphiphilic sizing agent with a concentration of 10-20%, and drying in a vacuum oven to obtain a new coating; Step S4 specifically includes the following steps: S4.1: Wash the glass fiber with ultrasound for 2-4 hours to remove the original surface coating on the glass fiber; S4.2: After drying in a vacuum oven at 90-110°C for 10-14 hours, immerse in an aqueous solution containing 8-12% of an amphiphilic sizing agent, and then dry in a vacuum oven for 10-14 hours to form a new coating on the surface of the glass fiber.

10. The amphiphilic sizing agent suitable for glass fiber / resin composite materials according to claim 9, characterized in that: After forming a new coating on the surface of the glass fiber, the following steps are included to obtain a glass fiber reinforced nylon 6 composite material: S5.1: Spread 50-70g of nylon pellets into a mold with the same size as the glass fiber, and preheat at 220-280℃ without pressure for 5-10min; S5.2: hot press at a pressure of 2-4 MPa for 2-5 min, hot press at a pressure of 10-15 MPa for 8-10 min, and immediately cold press at a pressure of 10-15 MPa on another hot press; S5.3: After the temperature of the mold is lowered to room temperature, the mold is demoulded to obtain a nylon 6 film, and several sheets of modified glass fiber and nylon 6 film are alternately stacked on a flat vulcanizer for hot pressing. After demoulding, the glass fiber reinforced nylon 6 composite material is obtained.

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