A low warpage glass fiber reinforced polypropylene composite material and a preparation method thereof

Abstract

This invention relates to the field of polymer composite materials technology, specifically disclosing a low-warpage glass fiber reinforced polypropylene composite material and its preparation method, comprising glass fiber-mica grafted masterbatch and polypropylene resin; the glass fiber-mica grafted masterbatch includes coupling agent modified glass fiber and coupling agent activated mica powder, forming a "glass fiber, coupling agent, mica powder" grafted structure, which makes the mica powder uniformly attached to the surface of the glass fiber. The glass fiber reinforced polypropylene composite material prepared using this grafted masterbatch utilizes the lamellar structure of mica powder to effectively reduce the anisotropy of the glass fiber reinforced polypropylene composite material, thereby giving the prepared composite material low warpage characteristics and effectively increasing its applicable application scenarios.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, and in particular to a low-warpage glass fiber reinforced polypropylene composite material and its preparation method. Background Technology

[0002] Glass fiber reinforced polypropylene (GFRP) is widely used in automotive parts, home appliances, and electronic products due to its excellent mechanical properties, heat resistance, and cost advantages. However, during the injection molding process, the orientation of the glass fibers causes a significant difference in shrinkage rates between the flow direction and the vertical direction, resulting in warping and deformation. This leads to severe product deformation, affecting assembly and use.

[0003] Currently, the mainstream methods for addressing warpage in glass fiber reinforced polypropylene composites fall into two categories: one is to reduce the overall crystallinity of the material by adding a large amount of elastomer resin (such as POE or EPDM), thereby reducing shrinkage differences caused by uneven crystallization; the other is to add a high proportion of lamellar fillers (such as mica or talc) to counteract the orientation shrinkage of the glass fiber, utilizing the isotropic nature of their two-dimensional structure. However, both methods have significant drawbacks: adding a large amount of elastomer significantly impairs key rigidity indicators of the composite material, such as tensile strength and flexural modulus; while a high proportion of lamellar powder filler can easily lead to filler agglomeration and uneven dispersion, which also reduces the material's rigidity and negatively impacts its impact toughness. Therefore, the industry urgently needs a new technological solution that can significantly reduce warpage while maintaining or even improving the material's rigidity and overall performance. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a low-warpage glass fiber reinforced polypropylene composite material and its preparation method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A low-warpage glass fiber reinforced polypropylene composite material includes glass fiber-mica graft masterbatch and polypropylene resin; The glass fiber-mica grafted masterbatch comprises coupling agent modified glass fiber and coupling agent activated mica powder, wherein the coupling agent is aminosilane.

[0006] Preferably, it also includes compatibilizers and processing aids.

[0007] Preferably, the compatibilizer is at least one of PP grafted with maleic anhydride or POE grafted with maleic anhydride.

[0008] Preferably, the processing aid is an antioxidant or a lubricant. The antioxidant is one or more combinations of antioxidant 1010, antioxidant DSTDP, and antioxidant 168; the lubricant is at least one of ethylene bis-stearamide, silicone, zinc stearate, lead stearate, barium stearate, calcium stearate, or pentaerythritol stearate.

[0009] Preferably, by weight, the polypropylene comprises 12-68 parts, the glass fiber-mica grafted masterbatch comprises 20-80 parts, the compatibilizer comprises 3-6 parts, and the processing aid comprises 0.5-2 parts.

[0010] Preferably, the preparation method of the glass fiber-mica grafted masterbatch is as follows: Step 1: Prepare a solution by mixing coupling agent, ethanol, and deionized water in a mass ratio of 1:40:10 (ethanol is the solvent, and water is used to hydrolyze the coupling agent). The coupling agent is aminosilane. Adjust the pH to 4-5 with acetic acid (a weakly acidic environment accelerates the hydrolysis of the coupling agent, generating active silanol groups -Si(OH)3). Stir for 30 minutes and let stand for 15 minutes (to ensure complete hydrolysis) to obtain the modified coupling agent solution. Step 2: Add glass fiber to the coupling agent modification solution at a solid-liquid ratio of 1:5, and stir at 60~70℃ for 2 hours (constant temperature water bath) to allow the silanol groups of the coupling agent to undergo a condensation reaction with the hydroxyl groups on the surface of the glass fiber (generating -Si-O-Si- covalent bonds), thus obtaining coupling agent modified glass fiber, forming a "glass fiber-silane coupling agent (with amino group)" structure; after the reaction is complete, filter out the glass fiber, and dry it at 110~120℃ for 2~3 hours (to cure the coupling agent and enhance the bonding stability) for later use; Step 3: Add mica powder to the remaining coupling agent solution above, with a solid-liquid ratio of 1:8, and stir at 50~60℃ for 1.5h to allow the amino groups of the coupling agent to combine with the hydroxyl groups on the surface of the mica powder; after filtration, dry at 90~100℃ for 3~4h to obtain coupling agent activated mica powder (with amino or silanol groups on the surface, which can further react with the coupling agent groups on the surface of glass fiber). Step 4: Mix glass fiber modified with coupling agent and mica powder activated with coupling agent at a mass ratio of 8:2 to 7:3 (adjust the ratio according to the target performance; too high a proportion of mica powder can easily lead to graft agglomeration). Add the mixture to a high-speed mixer at a speed of 1500 to 2000 rpm and mix at room temperature for 15 minutes to disperse evenly, thus obtaining the modified glass fiber and mica powder. Step 5: Add polypropylene resin, antioxidant, lubricant, and modified glass fiber and mica powder to a single-screw extruder. Under high temperature, shear force and heat cause the amino groups of the coupling agent on the glass fiber surface and the activated groups (amino or silanol groups) on the mica powder surface to undergo further condensation reaction or hydrogen bonding, forming a "glass fiber, coupling agent, mica powder" grafted structure; glass fiber-mica grafted masterbatch is prepared, with the mass ratio of polypropylene resin, antioxidant, and lubricant being (50~70):(25~45):(0.5~1.5):(0.5~2).

[0011] The preparation method of the low-warpage glass fiber reinforced polypropylene composite material described above includes the following steps: S1: Prepare a solution by mixing coupling agent, ethanol, and deionized water at a mass ratio of 1:40:10 (ethanol is the solvent, and water is used to hydrolyze the coupling agent). The coupling agent is an aminosilane. Adjust the pH to 4-5 with acetic acid (a weakly acidic environment accelerates the hydrolysis of the coupling agent, generating active silanol groups -Si(OH)3). Stir for 30 minutes and let stand for 15 minutes (to ensure complete hydrolysis) to obtain a modified coupling agent solution. Add glass fiber to the modified coupling agent solution at a solid-liquid ratio of 1:5 and stir at 60-70℃ for 2 hours (constant temperature water bath) to allow the silanol groups of the coupling agent to undergo a condensation reaction with the hydroxyl groups on the surface of the glass fiber (generating -Si-O-Si- covalent bonds), thus obtaining the modified glass fiber, forming a "glass fiber-silane coupling agent (with amino group)" structure. After the reaction is complete, filter out the glass fiber. Dry at 110~120℃ for 2~3h (to solidify the coupling agent and enhance bonding stability), and set aside. Add mica powder to the remaining coupling agent solution at a solid-liquid ratio of 1:8, and stir at 50~60℃ for 1.5h to allow the amino groups of the coupling agent to combine with the hydroxyl groups on the surface of the mica powder. After filtration, dry at 90~100℃ for 3~4h to obtain coupling agent-activated mica powder (with amino or silanol groups on the surface, which can further react with the coupling agent groups on the surface of the glass fiber). Mix the glass fiber modified by coupling agent and the activated mica powder by coupling agent at a mass ratio of 8:2~7:3 (adjust the ratio according to the target performance; too high a proportion of mica powder can easily lead to graft agglomeration). Add the mixture to a high-speed mixer at a speed of 1500~2000rpm and mix at room temperature for 15min to disperse evenly, to obtain the modified glass fiber and mica powder. S2: Polypropylene resin, antioxidant, lubricant, and modified glass fiber and mica powder are added to a single-screw extruder. Through shear force and heat at high temperature, the amino groups of the coupling agent on the glass fiber surface and the activated groups (amino or silanol groups) on the mica powder surface undergo further condensation reaction or hydrogen bonding to form a "glass fiber, coupling agent, mica powder" grafted structure; glass fiber-mica grafted masterbatch is prepared. S3: Polypropylene, compatibilizer, and processing aid are mixed and added from the main feed port of a single-screw extruder, while glass fiber-mica grafted masterbatch is added from the side feed port. After extrusion and granulation, a low-warpage glass fiber reinforced polypropylene composite material is obtained.

[0012] Preferably, by weight, step S3 comprises 10-78 parts of polypropylene, 10-40 parts of glass fiber-mica grafted masterbatch, 3-6 parts of compatibilizer, and 0.5-2 parts of processing aid.

[0013] Preferably, the mass ratio of the premixed filler to polypropylene resin, antioxidant, and lubricant in step S2 is (50~70):(25~45):(0.5~1.5):(0.5~2).

[0014] Application of the low-warpage glass fiber reinforced polypropylene composite material prepared according to the above preparation method in the production of automotive parts.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention achieves effective grafting through a two-step method: pretreating glass fiber and mica powder with a coupling agent to introduce reactive active groups on the surface of both; through the chemical reaction or physical coating of the active groups, the mica powder is anchored on the surface of the glass fiber to form a stable structure of "glass fiber, coupling agent, mica powder".

[0016] 2: In this invention, a glass fiber-mica grafted masterbatch comprising coupling agent-modified glass fiber and coupling agent-activated mica powder is prepared. Under the shear force and heat of a single-screw extruder at high temperature, the amino groups of the coupling agent on the glass fiber surface and the activated groups on the mica powder surface undergo further condensation reaction or hydrogen bonding, forming a "glass fiber, coupling agent, mica powder" grafted structure. This allows the mica powder to be uniformly attached to the glass fiber surface. The glass fiber reinforced polypropylene composite material prepared using this grafted masterbatch utilizes the lamellar structure of the mica powder to effectively reduce the anisotropy of the glass fiber reinforced polypropylene composite material, thereby giving the prepared composite material low warpage characteristics and effectively increasing its applicability in various scenarios.

[0017] 3: The preparation process of this invention is based on mature surface treatment and plastic processing technology, requiring no special equipment and using readily available raw materials, making it very suitable for large-scale industrial production. It has outstanding advantages in fields with stringent dimensional accuracy requirements, such as automotive lightweighting. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0019] Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0020] Polypropylene resin (PP): Grade M60RHC, Zhenhai Refining & Chemical.

[0021] Fiberglass: Chopped glass fiber (GF), grade 248A, Owens Corning.

[0022] Mica powder: Brand name MiapealS-10 / M-10, Jiangxi Liankai New Materials.

[0023] Aminosilane coupling agent: Brand KH550, Jiangsu Chenguang Coupling Agent Co., Ltd.

[0024] Compatibilizer: Brand CMG5701, Jia Yi Rong.

[0025] Antioxidant: 1010, BASF.

[0026] Antioxidant: 168, BASF.

[0027] Antioxidant: DSTP, BASF.

[0028] Lubricant: TAF, Suzhou Xingtai Optochemical Additives Co., Ltd.

[0029] An aminosilane coupling agent (such as KH-550: H2N(CH2)3Si(OCH3)3) is selected as the "bridging agent". Its amino group (-NH2) can form hydrogen bonds or condensation reactions with the hydroxyl groups (-OH) on the surface of mica powder, and the methoxy group (-OCH3) can condense with the hydroxyl groups on the surface of glass fiber. The specific steps are as follows: First, the preparation of glass fiber-mica grafted masterbatch: Step 1: Prepare a solution by mixing coupling agent, ethanol, and deionized water in a mass ratio of 1:40:10. The coupling agent is aminosilane. Adjust the pH to 4-5 with acetic acid, stir for 30 minutes, and let stand for 15 minutes to obtain the coupling agent modified solution. Step 2: Add glass fiber to the coupling agent modification solution at a solid-liquid ratio of 1:5 and stir at 60~70℃ for 2 hours to allow the silanol groups of the coupling agent to undergo a condensation reaction with the hydroxyl groups on the surface of the glass fiber, thus obtaining coupling agent modified glass fiber; after the reaction is complete, filter out the glass fiber and dry it at 110~120℃ for 2~3 hours for later use. Step 3: Add mica powder to the remaining coupling agent solution above, with a solid-liquid ratio of 1:8, and stir at 50~60℃ for 1.5h to allow the amino groups of the coupling agent to combine with the hydroxyl groups on the surface of the mica powder; after filtration, dry at 90~100℃ for 3~4h to obtain coupling agent activated mica powder. Step 4: Mix the glass fiber modified with coupling agent and the mica powder activated with coupling agent at a mass ratio of 8:2 to 7:3. Add the mixture to a high-speed mixer and mix at 1500 to 2000 rpm at room temperature for 15 minutes to disperse evenly, thus obtaining the modified glass fiber and mica powder. Step 5: Add polypropylene resin, antioxidant, lubricant, and modified glass fiber and mica powder to a single screw extruder. Through shear force and heat at high temperature, a grafted structure of "glass fiber, coupling agent, and mica powder" is formed. Glass fiber-mica grafted masterbatch is prepared. The mass ratio of polypropylene resin, antioxidant, and lubricant is (50~70):(25~45):(0.5~1.5):(0.5~2).

[0030] Secondly, the preparation method of the composite material includes the following steps: S1: Prepare a solution using a coupling agent:ethanol:deionized water mass ratio of 1:40:10. The coupling agent is aminosilane. Adjust the pH to 4-5 with acetic acid, stir for 30 min, and let stand for 15 min to obtain the coupling agent modified solution. Add glass fiber to the coupling agent modified solution at a solid-liquid ratio of 1:5, and stir at 60-70℃ for 2 h to allow the silanol groups of the coupling agent to condense with the hydroxyl groups on the glass fiber surface, obtaining the coupling agent modified glass fiber. After the reaction is complete, filter out the glass fiber and dry it at 110-120℃ for 2-3 hours. h, set aside; add mica powder to the remaining coupling agent solution above, with a solid-liquid ratio of 1:8, stir at 50~60℃ for 1.5h to allow the amino groups of the coupling agent to combine with the hydroxyl groups on the surface of the mica powder; after filtration, dry at 90~100℃ for 3~4h to obtain coupling agent activated mica powder; mix according to the mass ratio of coupling agent modified glass fiber: coupling agent activated mica powder = 8:2~7:3, add to a high-speed mixer, speed 1500~2000rpm, mix at room temperature for 15min to disperse evenly, and obtain modified glass fiber and mica powder; S2: Polypropylene resin, antioxidant, lubricant, and modified glass fiber and mica powder are added to a single screw extruder and subjected to shear force and heat at high temperature to form a grafted structure of "glass fiber, coupling agent, and mica powder"; glass fiber-mica grafted masterbatch is prepared. S3: Polypropylene, compatibilizer, and processing aid are mixed and added from the main feed port of a single-screw extruder, while glass fiber-mica grafted masterbatch is added from the side feed port. After extrusion and granulation, a low-warpage glass fiber reinforced polypropylene composite material is obtained.

[0031] Example 1 Preparation of glass fiber-mica grafted masterbatch: Preparation of coupling agent hydrolysate: Mix KH-550, anhydrous ethanol and deionized water in a mass ratio of 1:40:10, add glacial acetic acid to adjust the pH to 4.5, stir for 30 minutes, let stand for 15 minutes to obtain a completely hydrolyzed silane solution.

[0032] Preparation of coupling agent modified glass fiber: Take 100g of glass fiber and immerse it in 500g of the above silane solution at a solid-liquid ratio of 1:5. Then, stir the mixture at 65℃ for 2 hours. After filtration and washing with ethanol, dry the glass fiber at 115℃ for 2.5 hours to obtain coupling agent modified glass fiber.

[0033] Preparation of coupling agent-activated mica: Add 50g of mica powder to the remaining silane solution above, and stir in a water bath at 55℃ for 1.5 hours. After filtration, dry at 100℃ for 3 hours to obtain coupling agent-activated mica powder.

[0034] Preparation of masterbatch: 80g of coupling agent-modified glass fiber and 20g of coupling agent-activated mica powder were added to a high-speed mixer and mixed at 1800rpm for 15 minutes to obtain a premixed filler. The premixed filler was then mixed evenly with 63g of PP resin, 0.5g of antioxidant 1010, 1.0g of antioxidant 168, and 1.5g of EBS. The mixture was then melt-extruded and granulated using a single-screw extruder (temperature 170-200℃, speed 400rpm) to obtain glass fiber-mica grafted masterbatch.

[0035] Preparation of composite materials: Weigh the raw materials according to the following formula: 38 parts polypropylene, 4 parts compatibilizer (PP-g-MAH), 0.3 parts antioxidant (1010 / 168=1 / 2), 0.5 parts lubricant (EBS), and 50 parts of the above glass fiber-mica grafted masterbatch.

[0036] Polypropylene, compatibilizer, antioxidant, and lubricant were premixed and fed into the main feed port of a twin-screw extruder (ZSK26, L / D=40); glass fiber-mica grafted masterbatch was fed into the side feed port. The extrusion temperature was 180-210℃, the screw speed was 350 rpm, and vacuum degassing was used. The extruded strip was water-cooled, pelletized, and dried at 80℃ for 4 hours to obtain the composite material.

[0037] Example 2 70g of coupling agent-modified glass fiber and 30g of coupling agent-activated mica powder (mass ratio 7:3) were mixed. The remaining steps, including hydrolysate preparation, glass fiber and mica treatment, melt extrusion formulation (63g PP, 1.5g antioxidant, 1.5g EBS), and process parameters, were the same as in Example 1. Glass fiber-mica grafted masterbatch was obtained.

[0038] Preparation of the composite material: 38 parts polypropylene, 4 parts compatibilizer (PP-g-MAH), 0.3 parts antioxidant (1010 / 168=1 / 2), 0.5 parts lubricant (EBS), and 50 parts of the above-mentioned glass fiber-mica grafted masterbatch. The preparation process is exactly the same as that of the composite material preparation process in Example 1.

[0039] Example 3 70g of coupling agent-modified glass fiber and 30g of coupling agent-activated mica powder (mass ratio 7:3) were mixed. The remaining steps, including hydrolysate preparation, glass fiber and mica treatment, melt extrusion formulation (63g PP, 1.5g antioxidant, 1.5g EBS), and process parameters, were the same as in Example 1. Glass fiber-mica grafted masterbatch was obtained.

[0040] Preparation of the composite material: 48 parts polypropylene, 4 parts compatibilizer (PP-g-MAH), 0.3 parts antioxidant (1010 / 168=1 / 2), 0.5 parts lubricant (EBS), and 40 parts of the above-mentioned glass fiber-mica grafted masterbatch. The preparation process is exactly the same as that of the composite material preparation process in Example 1.

[0041] Example 4 The preparation method of the glass fiber-mica grafted masterbatch is the same as that in Example 1, and the relevant glass fiber-mica grafted masterbatch is finally obtained.

[0042] Preparation of the composite material: 68 parts polypropylene, 3 parts compatibilizer (PP-g-MAH), 0.5 parts antioxidant (1010 / 168=1 / 2), 0.5 parts lubricant (EBS), and 20 parts of the above-mentioned glass fiber-mica grafted masterbatch. The preparation process is exactly the same as that of the composite material preparation process in Example 1.

[0043] Example 5 The preparation method of the glass fiber-mica grafted masterbatch is the same as that in Example 2, and the relevant glass fiber-mica grafted masterbatch is finally obtained.

[0044] Preparation of the composite material: 12 parts polypropylene, 6 parts compatibilizer (PP-g-MAH), 1.8 parts antioxidant (1010 / 168 / DSTDP=1 / 2 / 0.5), 0.5 parts lubricant (EBS), and 80 parts of the above-mentioned glass fiber-mica grafted masterbatch. The preparation process is exactly the same as that of the composite material preparation process in Example 1. Comparative Example 1 This comparative example uses the ordinary blending method. The raw materials were weighed according to the following formula: 58 parts polypropylene, 4 parts compatibilizer (PP-g-MAH), 0.3 parts antioxidant (1010 / 168=1 / 2), 0.5 parts lubricant (EBS), 24 parts untreated glass fiber, and 6 parts untreated mica powder.

[0045] All raw materials were added at once from the main feed port of the twin-screw extruder, and the extrusion granulation process was the same as in Example 1 to obtain the comparative material.

[0046] Comparative Example 2 This comparative example is a pure glass fiber reinforced system. The raw materials were weighed according to the following formula: 58 parts polypropylene, 4 parts compatibilizer (PP-g-MAH), 0.3 parts antioxidant (1010 / 168=1 / 2), 0.5 parts lubricant (EBS), and 30 parts untreated glass fiber.

[0047] All raw materials were added at once from the main feed port of the twin-screw extruder, and the extrusion granulation process was the same as in Example 1 to obtain the comparative material.

[0048] Performance testing and characterization: Microscopic morphology observation: The impact specimens of Example 1 and Comparative Example 1 were fractured, sputtered with gold, and the fracture surfaces were observed using a scanning electron microscope. In the fracture surface of Example 1, mica sheets were seen to be tightly attached to or embedded in the glass fiber surface, forming a "bundled" structure; in Comparative Example 1, the glass fiber and mica were dispersed and independent, with clear interfaces and debonding pores.

[0049] Mechanical and warpage performance testing: The particles from each embodiment and comparative example were injection molded into standard test strips and 300mm × 300mm × 3mm plates. The testing standards are as follows: Tensile properties: tested according to ISO 527-2 standard; Bending performance: tested according to ISO 178 standard; Notched impact strength of simply supported beams: tested according to ISO 179-1 standard; Warpage deformation: After the injection molded plate is placed at (23±2)℃ for 48 hours, the maximum vertical distance of its four corners from the plane is measured and the average value is taken; Shrinkage difference: Measure the shrinkage of the standard specimen in the flow direction (MD) and vertical direction (TD) and calculate the absolute difference |MD-TD|.

[0050] The test results are recorded in Table 1 below: Table 1 Test results of composite material performance of the examples and comparative examples.

[0051] Table 1 In summary, both glass fiber and mica powder are polar inorganic materials, but when directly mixed, they are prone to uneven dispersion and weak bonding due to "surface energy mismatch" and "lack of strong interaction". This invention achieves effective grafting through a two-step method: pretreating glass fiber and mica powder with a coupling agent to introduce reactive active groups on the surface of both, thereby activating the interface; and anchoring mica powder to the surface of glass fiber through chemical reaction or physical coating of the active groups, thereby achieving bonded grafting and forming a stable structure of "glass fiber, coupling agent, and mica powder".

[0052] As shown in Table 1, the warpage deformation of all Examples 1-5 ranged from 1.0 to 2.0 mm, and the shrinkage rate differed by 0.16% to 0.28%, both significantly lower than the two comparative examples. This directly proves that the "glass fiber-mica grafted structure" can effectively reduce the anisotropic shrinkage of the material, fundamentally solving the warpage problem and achieving a low warpage effect. The flexural modulus of Example 1 was 4950 MPa, significantly higher than that of Comparative Example 1 (4410 MPa) and also superior to that of Comparative Example 2 (4730 MPa). This breaks through the limitation of traditional methods that "reducing warpage inevitably leads to a loss of rigidity," achieving a synergistic improvement in both low warpage and high rigidity. While achieving excellent low warpage and high rigidity, the examples also demonstrated superior impact toughness compared to Comparative Example 1, exhibiting a good balance of comprehensive performance.

[0053] Examples 4 and 5 represent the boundary conditions for the amounts of polypropylene and masterbatch used in the claims, respectively. The data show that even under these boundary conditions, the low warpage and high rigidity characteristics of the present invention are still maintained, strongly supporting the scope of the claims.

[0054] In summary, this invention successfully prepared a glass fiber reinforced polypropylene composite material with low warpage, high rigidity, and good toughness by constructing a "glass fiber-coupling agent-mica" chemical grafting structure. The overall performance is significantly better than that of traditional blended materials, and it has broad application prospects in the field of lightweight precision automotive components.

[0055] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A low-warpage glass fiber reinforced polypropylene composite material, characterized in that, Including fiberglass-mica grafted masterbatch and polypropylene resin; The glass fiber-mica grafted masterbatch comprises coupling agent modified glass fiber and coupling agent activated mica powder, wherein the coupling agent is an aminosilane coupling agent, and the aminosilane coupling agent is γ-aminopropyltrimethoxysilane.

2. The low-warpage glass fiber reinforced polypropylene composite material according to claim 1, characterized in that, It also includes compatibilizers and processing aids.

3. The low-warpage glass fiber reinforced polypropylene composite material according to claim 2, characterized in that, The compatibilizer is at least one of PP grafted with maleic anhydride or POE grafted with maleic anhydride.

4. The low-warpage glass fiber reinforced polypropylene composite material according to claim 2, characterized in that, The processing aid is an antioxidant and a lubricant. The antioxidant is one or more combinations of antioxidant 1010, antioxidant DSTDP, and antioxidant 168. The lubricant is at least one of ethylene bis-stearamide, silicone, zinc stearate, lead stearate, barium stearate, calcium stearate, or pentaerythritol stearate.

5. The low-warpage glass fiber reinforced polypropylene composite material according to claim 2, characterized in that, By weight, the polypropylene comprises 12-68 parts, the glass fiber-mica grafted masterbatch comprises 20-80 parts, the compatibilizer comprises 3-6 parts, and the processing aid comprises 0.5-2 parts.

6. The low-warpage glass fiber reinforced polypropylene composite material according to claim 1, characterized in that, The preparation method of the glass fiber-mica grafted masterbatch is as follows: Step 1: Prepare a coupling agent modified solution, wherein the coupling agent is an aminosilane; Step 2: Add glass fiber to the coupling agent modified solution and react to obtain coupling agent modified glass fiber; Step 3: Add mica powder to the remaining coupling agent modified solution and react to obtain coupling agent activated mica powder; Step 4: Mix the coupling agent-modified glass fiber with the coupling agent-activated mica powder to obtain the modified glass fiber and mica powder.

7. A method for preparing a low-warpage glass fiber reinforced polypropylene composite material according to any one of claims 1-6, characterized in that, Includes the following steps: S1: Prepare a solution by mixing coupling agent, ethanol and deionized water in a mass ratio of 1:40:

10. The coupling agent is aminosilane. Adjust the pH to 4-5 with acetic acid, stir for 30 min, and let stand for 15 min to obtain the coupling agent modified solution. Glass fiber was added to a coupling agent modified solution with a solid-liquid ratio of 1:5 and stirred at 60~70℃ for 2 hours to allow the silanol groups of the coupling agent to undergo a condensation reaction with the hydroxyl groups on the surface of the glass fiber, thus obtaining coupling agent modified glass fiber. After the reaction is complete, filter out the glass fiber, dry it at 110~120℃ for 2~3 hours, and set it aside. Add mica powder to the remaining coupling agent solution above, with a solid-liquid ratio of 1:8, and stir at 50~60℃ for 1.5 hours to allow the amino groups of the coupling agent to combine with the hydroxyl groups on the surface of the mica powder. After filtration, dry it at 90~100℃ for 3~4 hours to obtain coupling agent activated mica powder. Mix the modified glass fiber and the activated mica powder at a mass ratio of 8:2~7:3, add it to a high-speed mixer, and mix at 1500~2000 rpm at room temperature for 15 minutes to disperse it evenly, thus obtaining the modified glass fiber and mica powder. S2: Polypropylene resin, antioxidant, lubricant, modified glass fiber and mica powder are added to a single screw extruder and subjected to shear force and heat at high temperature to form a "glass fiber, coupling agent, mica powder" grafted structure; glass fiber-mica grafted masterbatch is prepared. S3: Polypropylene, compatibilizer, and processing aid are mixed and added from the main feed port of a single-screw extruder, while glass fiber-mica grafted masterbatch is added from the side feed port. After extrusion and granulation, a low-warpage glass fiber reinforced polypropylene composite material is obtained.

8. The method for preparing a low-warpage glass fiber reinforced polypropylene composite material according to claim 7, characterized in that, In step S3, by weight, there are 10-78 parts of polypropylene, 10-40 parts of glass fiber-mica grafted masterbatch, 3-6 parts of compatibilizer, and 0.5-2 parts of processing aid.

9. The method for preparing a low-warpage glass fiber reinforced polypropylene composite material according to claim 7, characterized in that, In step S2, the mass ratio of the modified glass fiber to mica powder, polypropylene resin, antioxidant, and lubricant is (50~70):(25~45):(0.5~1.5):(0.5~2).

10. The application of the low-warpage glass fiber reinforced polypropylene composite material prepared by any one of the preparation methods according to claims 7-9 in the production of automotive parts.

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