An amphiphilic sizing agent suitable for glass fiber / resin composite materials

Abstract

The invention discloses a kind of amphiphilic sizing agent applicable to glass fiber / resin composite material, reversible addition-fragmentation chain transfer polymerization method polymerizes glycidyl methacrylate and ethyl trimethyl ammonium chloride of methacrylate, is combined into glycidyl ester ethyl trimethyl ammonium chloride, and then free radical polymerization technology is utilized to introduce dopamine methacrylamide, obtains the amphiphilic sizing agent.The amphiphilic sizing agent of the present invention can be applied to glass fiber surface without fillings such as plasticizer, coupling agent and inhibitor, and can regulate the coating performance and the binding performance of product by changing structural unit ratio, the amphiphilic sizing agent can form covalent bonding effect by epoxy and the hydroxyl group on glass fiber, positively charged can also form electrostatic action combination with glass fiber surface negative charge, dopamine group can form powerful hydrogen bond effect with group on resin, contributes to realize efficient load transfer.

Description

Technical Field

[0001] The invention relates to the technical field of one-dimensional material preparation, in particular to an amphiphilic sizing agent suitable for glass fiber / resin composite materials. Background Art

[0002] Glass fiber (GF)-reinforced thermoplastic resin composites are widely used in industries such as automotive, aerospace, and sports equipment due to their excellent processability and cost-effectiveness. However, interfacial compatibility between the GF and the matrix remains a key challenge in improving the performance of these materials. To overcome these obstacles, researchers have explored various methods to enhance the bond between GF and the resin, with the application of suitable sizing agents being considered an effective strategy. Given the urgent industrial demand for high mechanical properties in GF / resin composites, the role of sizing agents in reinforcing the interfacial properties of GF / resin composites needs to be improved. Summary of the Invention

[0003] In view of the above-mentioned shortcomings, the present invention proposes an amphiphilic sizing agent suitable for glass fiber / resin composite materials, which can form a strong interfacial adhesion between the glass fiber and the resin, thereby helping to achieve 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 polymerized by a reversible addition-fragmentation chain transfer polymerization method on glycidyl methacrylate and ethyltrimethylammonium methacrylate chloride, and then dopamine methacrylamide is introduced by free radical polymerization technology, and the general structural formula thereof is:

[0005]

[0006] Among them, 2<x<84, 1<y<42, 1<z<34.

[0007] As an improvement, the preparation of the amphiphilic sizing agent comprises the following steps:

[0008] S1: performing an amination reaction on dopamine hydrochloride and a tetrahydrofuran solution containing methacrylic anhydride under alkaline conditions, subsequently adding sodium hydroxide to adjust the pH to alkaline, and reacting at low temperature under nitrogen protection. After the reaction is completed, separation and purification are performed using hydrochloric acid, ethyl acetate, anhydrous sodium sulfate or anhydrous magnesium sulfate, and n-pentane to obtain dopamine methacrylamide;

[0009] S2: glycidyl methacrylate and ethyltrimethylammonium methacrylate chloride are subjected to a reversible addition-fragmentation chain transfer polymerization method in the presence of trithiocarbonate and ammonium persulfate as catalysts to obtain glycidyl methacrylate-ethyltrimethylammonium chloride;

[0010] 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.

[0011] 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.

[0012] As an improvement, the step S1 specifically includes the following steps:

[0013] S1.1: Dissolve 10-30 g of sodium borate and 3-13 g of sodium bicarbonate in 170-230 mL of deionized water, with the reaction concentration of the sodium borate being 5%-20% and the reaction concentration of the sodium bicarbonate being 1%-10%. After stirring under nitrogen, add 5-15 g of dopamine hydrochloride to the solution, and then dropwise add 6-12 mL of methacrylic anhydride dissolved in 30-50 mL of tetrahydrofuran solution.

[0014] S1.2: Maintain the pH of the solution at 8-10 by adding sodium hydroxide. After reacting at 0-8°C under nitrogen for 20-28 h, add 80-120 mL of ethyl acetate to the solution while slowly stirring to separate the organic and inorganic phases.

[0015] S1.3: Adjust the pH of the solution to below 2 by dropwise addition of hydrochloric acid. Separate the organic layer using a separatory funnel. Wash the organic layer several times with 70-110 mL of ethyl acetate. Remove any residual moisture from the organic layer by vacuum filtration using 2-8 g of anhydrous magnesium sulfate.

[0016] S1.4: Add 20-80 mL of n-pentane to precipitate dopamine methacrylamide and store the product in a refrigerator.

[0017] As an improvement, the amount of glycidyl methacrylate in step S2 is 1-3 parts by weight, and its reaction concentration is 10%-20%, the amount of ethyltrimethylammonium chloride methacrylate is 0.5-1.5 parts by weight, and its reaction concentration is 5%-10%, the amount of trithiocarbonate is 0.005-0.02 parts by weight, and the amount of ammonium persulfate is 0.002-0.01 parts by weight.

[0018] As an improvement, step S2 specifically includes: mixing 5-10 g of glycidyl methacrylate, 2-6 g of ethyltrimethylammonium methacrylate chloride, 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 flask, and polymerizing with ammonium persulfate as a starter at 60-80° C. under nitrogen protection; and reacting the mixture under vigorous stirring for 7-12 hours.

[0019] As an improvement, 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.

[0020] As an improvement, the step S3 specifically includes: mixing 0.3-1.1 g of dopamine methacrylamide with 0.9-3.3 g of glycidyl ester-ethyltrimethylammonium chloride solution, and reacting them under nitrogen protection and the action of cumene hydroperoxide at room temperature for 7-11 hours.

[0021] As an improvement, the method further includes S4: soaking 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;

[0022] Step S4 specifically includes the following steps:

[0023] S4.1: Ultrasonic cleaning of the glass fiber for 2-4 hours to remove the original surface coating on the glass fiber;

[0024] 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 glass fiber surface.

[0025] As an improvement, 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:

[0026] S5.1: Place 50-70 g of nylon pellets into a mold of the same size as the glass fiber and preheat at 220-280°C without pressure for 5-10 minutes.

[0027] S5.2: Hot press at 2-4 MPa for 2-5 min, then at 10-15 MPa for 8-10 min. Immediately remove and cold press at 10-15 MPa in another hot press.

[0028] S5.3: The mold is cooled to room temperature and then demolded to obtain a nylon 6 film. Several sheets of modified glass fiber and nylon 6 film are alternately stacked and hot-pressed on a flat vulcanizer. After demolding, the glass fiber reinforced nylon 6 composite material is obtained.

[0029] Compared with the prior art, the advantages of the present invention are:

[0030] (1) An innovative amphiphilic sizing agent was developed. Glycidyl methacrylate and ethyltrimethylammonium methacrylate chloride were polymerized by reversible addition-fragmentation chain transfer polymerization, followed by the introduction of dopamine methacrylamide using 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 the glass fiber and the resin, which helps to achieve efficient load transfer and ultimately significantly improve the mechanical properties of the glass fiber / resin composite material.

[0031] (2) The amphiphilic sizing agent provided by the present invention has a simple formula and can be applied to the surface of glass fiber without the need for fillers such as 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 group 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.

[0032] (3) The amphiphilic sizing agent is easily soluble in water and can be evenly coated on the surface of the glass fiber. The wettability of the glass fiber in the resin after sizing is improved, making the composite material easier to shape during processing, reducing processing difficulty and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0034] Figure 1 This is a general structural formula of an amphiphilic sizing agent suitable for glass fiber / resin composite materials;

[0035] Figure 2 Schematic diagram of the glycidyl ester-ethyltrimethylammonium chloride reaction process;

[0036] Figure 3 Schematic diagram of the reaction process of amphiphilic sizing agent;

[0037] Figure 4 Schematic diagram of the interface effect of glass fiber / resin composite materials. DETAILED DESCRIPTION

[0038] Example 1

[0039] S1.1: Dissolve 20 g of sodium borate and 8 g of sodium bicarbonate in 200 mL of deionized water. After stirring under nitrogen, add 10 g of dopamine hydrochloride to the solution. Add dropwise 9.4 mL of methacrylic anhydride dissolved in 40 mL of tetrahydrofuran.

[0040] S1.2: Maintain the pH of the solution at 8-10 by adding sodium hydroxide. After reacting at 4°C under nitrogen for 24 h, add 100 mL of ethyl acetate to the solution while slowly stirring to separate the organic and inorganic phases.

[0041] S1.3: Adjust the pH of the solution to below 2 by dropwise addition of hydrochloric acid. Separate the organic layer using a separatory funnel. Wash the organic layer three times with 90 mL of ethyl acetate. Then, remove any residual moisture by vacuum filtration using 5 g of anhydrous magnesium sulfate.

[0042] S1.4: Add 50 mL of n-pentane to precipitate dopamine methacrylamide and store the product in a refrigerator at 4°C.

[0043] S2: Combine 7.52 g of glycidyl methacrylate, 4.42 g of ethyltrimethylammonium methacrylate chloride, 0.136 g of trithiocarbonate, 0.044 g of ammonium persulfate, and 50 mL of water in a three-necked flask and polymerize with ammonium persulfate as an initiator at 70°C under nitrogen. The mixture is stirred vigorously for 9 h.

[0044] S3: 0.72 g of dopamine methacrylamide was mixed with 2.19 g of polymethacrylic acid (glycidyl ester-ethyltrimethylammonium chloride) solution, and the mixture was reacted under nitrogen protection and the presence of cumene hydroperoxide at room temperature for 9 hours;

[0045] S4.1: Ultrasonicate a 25 cm × 25 cm glass fiber for 3 hours to remove the original surface coating on the glass fiber.

[0046] S4.2: After drying in a vacuum oven at 100°C for 12 h, the glass fiber was immersed in an aqueous solution containing 10% amphiphilic sizing agent and then dried in a vacuum oven for 12 h to form a new coating on the glass fiber surface;

[0047] S5.1: Spread 60 g of nylon pellets into a 25 cm × 25 cm mold and preheat at 250°C without pressure for 8 min.

[0048] S5.2: Hot press at 3 MPa for 3.5 min, then at 13 MPa for 9 min. Immediately remove and cold press at 13 MPa in another hot press.

[0049] S5.3: The mold is cooled to room temperature and demolded to obtain a nylon 6 film. Seven sheets of modified glass fibers and nine sheets of nylon 6 films are alternately stacked and hot-pressed on a flat vulcanizer. After demolding, the glass fiber reinforced nylon 6 composite material is obtained.

[0050] The interlaminar shear strength (ILSS) is used to characterize the bond strength between layers of carbon fiber composite laminates. ASTM D2344 is used for testing, 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.

[0051] The interlaminar shear strength of the glass fiber reinforced nylon 6 composite material obtained in Example 1 is 35 MPa.

[0052] Example 2

[0053] S4.2: After drying in a vacuum oven at 100°C for 12 h, the glass fiber was immersed in a 20% aqueous solution of an amphiphilic sizing agent and then dried in a vacuum oven for 12 h to form a new coating on the glass fiber surface;

[0054] Other experimental steps are consistent with those in Example 1.

[0055] The interlaminar shear strength of the glass fiber reinforced nylon 6 composite material obtained in Example 2 is 31 MPa, which is lower than that in Example 1. This is because the high concentration of the amphiphilic sizing agent entangles and wraps the reactive binding sites within the molecular chain, preventing good contact with the glass fiber and resin.

[0056] Example 3

[0057] S2: Combine 7.52 g of glycidyl methacrylate, 4.42 g of ethyltrimethylammonium methacrylate chloride, 0.136 g of trithiocarbonate, 0.044 g of ammonium persulfate, and 50 mL of water in a three-necked flask and polymerize with ammonium persulfate as an initiator at 70°C under nitrogen. The mixture is stirred vigorously for 9 h.

[0058] S3: 1.44 g of dopamine methacrylamide was mixed with 2.19 g of polymethacrylic acid (glycidyl ester-ethyltrimethylammonium chloride) solution, and the mixture was reacted under nitrogen protection and the presence of cumene hydroperoxide at room temperature for 9 hours;

[0059] Other experimental steps are consistent with those in Example 1.

[0060] The interlaminar shear strength of the composite material obtained in Example 3 was 25 MPa. The low strength was due to the high molecular weight leading to difficulty in bonding and poor fluidity, resulting in an insignificant reinforcement effect.

[0061] Comparative Example

[0062] A 25 cm × 25 cm glass fiber was ultrasonically cleaned for 3 hours to remove the existing surface coating. The fiber was then dried in a vacuum oven at 100°C for 12 hours, immersed in a solution containing pure water, and then dried in a vacuum oven for 12 hours. The fiber was then composited with nylon using the same procedures as in Examples 5.1, 5.2, and 5.3.

[0063] The interlaminar shear strength of the composite material obtained in the comparative example is 20 MPa.

[0064] The modified interlayer shear strength of the Example 1 was 35 MPa, a 75% increase over the 20 MPa of the Comparative Example. This is due to the moderate molecular weight and appropriate hydrophilic-hydrophobic ratio of the amphiphilic sizing agent in Example 1, which enables good bonding with the glass fiber and resin, achieving efficient load transfer and ultimately significantly improving the mechanical properties of the glass fiber / resin composite.

[0065] Amphiphilic sizing agent structure such as Figure 1 As shown, in the structural formula, 2<x<84, 1<y<42, 1<z<34. Figure 2 This is a schematic diagram of the reaction process of polymethacrylic acid (glycidyl ester-ethyltrimethylammonium chloride);

[0066] Figure 3 、 Figure 4 They are respectively a schematic diagram of the reaction process of the amphiphilic sizing agent and a schematic diagram of the interface effect of the glass fiber / resin composite material.

[0067] The above description is merely a description of the preferred embodiment of the present invention and is not to be construed as limiting the scope of the claims. The present invention is not limited to the above embodiment, and variations in the specific structure are permitted. Any variations within the scope of the independent claims of the present invention are also within the scope of protection of the present invention.

Claims

1. An amphiphilic sizing agent suitable for glass fiber / resin composite materials, characterized in that: Glycidyl methacrylate and ethyltrimethylammonium methacrylate are polymerized by a reversible addition-fragmentation chain transfer polymerization method to form glycidyl methacrylate-ethyltrimethylammonium chloride, and then dopamine methacrylamide is introduced by free radical polymerization technology to obtain the amphiphilic sizing agent, whose general structural formula is: Among them, 2<x<84, 1<y<42, 1<z<34, The preparation of the amphiphilic sizing agent comprises the following steps: S1: performing an amination reaction on dopamine hydrochloride and a tetrahydrofuran solution containing methacrylic anhydride under alkaline conditions, i.e., a solution containing 5%-20% sodium borate and 1%-10% sodium bicarbonate, followed by adding sodium hydroxide to adjust the pH to 8-10, and reacting at 0-8°C under nitrogen for 20-28 hours. After the reaction is completed, the pH value of the solution is adjusted to below 2 with hydrochloric acid, and then ethyl acetate, anhydrous sodium sulfate or anhydrous magnesium sulfate, and n-pentane are added for separation and purification to obtain dopamine methacrylamide; S2: glycidyl methacrylate and ethyltrimethylammonium methacrylate chloride are subjected to a reversible addition-fragmentation chain transfer polymerization method in the presence of trithiocarbonate and ammonium persulfate as catalysts to obtain glycidyl methacrylate-ethyltrimethylammonium 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.

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

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

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

5. The amphiphilic sizing agent suitable for glass fiber / resin composite materials according to claim 1, characterized in that: The step S2 specifically comprises: mixing 5-10 g of glycidyl methacrylate, 2-6 g of ethyltrimethylammonium chloride 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 flask, and polymerizing the mixture with ammonium persulfate as a starter at 60-80° C. under nitrogen protection; and reacting the mixture under vigorous stirring for 7-12 hours.

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

7. The amphiphilic sizing agent suitable for glass fiber / resin composite materials according to claim 1, 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 them under nitrogen protection and the action of cumene hydroperoxide at room temperature for 7-11 hours.

8. The amphiphilic sizing agent suitable for glass fiber / resin composite materials according to claim 1, characterized in that: The process further comprises S4: soaking 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: Ultrasonic cleaning of 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°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 glass fiber surface.

9. The amphiphilic sizing agent suitable for glass fiber / resin composite materials according to claim 8, 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: Place 50-70 g of nylon pellets into a mold of the same size as the glass fiber and preheat at 220-280°C without pressure for 5-10 minutes. S5.2: Hot press at 2-4 MPa for 2-5 min, then at 10-15 MPa for 8-10 min. Immediately remove and cold press at 10-15 MPa in another hot press. S5.3: The mold is cooled to room temperature and then demolded to obtain a nylon 6 film. Several sheets of modified glass fiber and nylon 6 film are alternately stacked and hot-pressed on a flat vulcanizer. After demolding, the glass fiber reinforced nylon 6 composite material is obtained.

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