Glass fiber reinforced polyurethane composite material and preparation process thereof

Abstract

The invention relates to a glass fiber reinforced polyurethane composite material and a preparation process thereof, and belongs to the technical field of polymer composite materials. The formula of the glass fiber reinforced polyurethane composite material comprises the following components in parts by weight: 60-80 parts of thermoplastic polyurethane, 15-25 parts of modified glass fiber, 2-5 parts of an interface modifier, 1-2 parts of an antioxidant and 1-3 parts of a lubricant. A covalently bonded silane coupling agent-nano silicon dioxide composite transition layer is formed by mixing chopped glass fibers and continuous glass fibers to construct a synergistic enhancement system and combining argon-oxygen plasma activation and nano silicon dioxide sol coating processes, so that the interfacial shear strength is remarkably improved, the stress concentration is effectively relieved, and the service life is prolonged. The tensile strength and the impact strength of the material are obviously improved.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer composite materials and relates to a glass fiber reinforced polyurethane composite material and a preparation process thereof. Background Art

[0002] In the field of polymer composites, glass fiber reinforced polyurethane composites are widely used in the automotive, electronics, and aerospace industries because they combine the toughness of the polyurethane matrix with the high rigidity of the glass fiber. However, conventional glass fiber reinforced polyurethane composites still face the following technical bottlenecks: First, the polarity difference between the glass fiber and the polyurethane matrix leads to poor interfacial compatibility, low stress transfer efficiency, and easy interfacial debonding, which limits the improvement of mechanical properties. Second, the reinforcement structure is simple. The reinforcement system using only chopped glass fiber or continuous glass fiber has anisotropic defects. The former easily leads to insufficient material anti-warping performance, while the latter has poor impact toughness due to rapid crack propagation in the vertical direction. Third, there is a contradiction between processing and performance. Although the addition of glass fiber can improve strength, it is easy to cause agglomeration, resulting in reduced melt fluidity and increased surface defects in the product. In addition, traditional silane coupling agent modification makes it difficult to balance interfacial bonding and dispersion uniformity. Therefore, there is an urgent need for a glass fiber reinforced polyurethane composite with good interfacial bonding and a preparation process. Summary of the Invention

[0003] The purpose of the present invention is to provide a glass fiber reinforced polyurethane composite material and a preparation process thereof, which has the characteristics of excellent mechanical properties.

[0004] The purpose of the present invention can be achieved through the following technical solutions: A glass fiber reinforced polyurethane composite material, wherein the glass fiber reinforced polyurethane composite material has the following formula: calculated by weight, 60-80 parts of thermoplastic polyurethane, 15-25 parts of modified glass fiber, 2-5 parts of interface modifier, 1-2 parts of antioxidant, and 1-3 parts of lubricant; Wherein, the preparation method of the modified glass fiber is as follows: S1-1: Chopped glass fibers were mixed with continuous glass fibers and then treated with plasma for 60-80 s in a plasma atmosphere of argon and oxygen in a volume ratio of 4-6:1 to obtain pretreated glass fibers. S1-2: 10-20 parts by weight of pretreated glass fiber are added to 80-90 parts by weight of nano-silica sol, ultrasonically mixed for 60-90 minutes, then washed with deionized water and vacuum dried at 120° C. for 12-16 hours to obtain the modified glass fiber.

[0005] As a preferred technical solution of the present invention, the chopped glass fibers and the continuous glass fibers in S1-1 are mixed in a mass ratio of (2-3):1.

[0006] As a preferred technical solution of the present invention, the interface modifier is one or more of the silane coupling agents KH-550, KH-560, and KH-570.

[0007] As a preferred technical solution of the present invention, the power of the plasma in S1-1 is 200~300W, the electrode spacing is 100~120 mm, and the vacuum degree is 50~100 Pa.

[0008] As a preferred technical solution of the present invention, the particle size of the nano-silica sol in S1-2 is 20 nm, and the solid content of the sol is 10-20%.

[0009] As a preferred technical solution of the present invention, the power of the ultrasound in S1-2 is 100-150 W, and the temperature of the ultrasound is 35-45°C.

[0010] As a preferred technical solution of the present invention, the antioxidant is one or more of antioxidant 1010, antioxidant 264 and antioxidant 1076.

[0011] As a preferred technical solution of the present invention, the lubricant is one or a combination of zinc stearate and ethylene bisstearamide.

[0012] A preparation process of a glass fiber reinforced polyurethane composite material, the specific steps of the preparation process are as follows: S9-1: The modified glass fiber and the interfacial modifier were mixed according to the formula ratio for 5-10 minutes at a mixing speed of 800-900 rpm. The thermoplastic polyurethane, antioxidant, and lubricant were then added in sequence and further mixed for 10-20 minutes at a mixing speed of 600-700 rpm to obtain a premix. S9-2: Add the premix to a twin-screw extruder with a screw speed of 300-500 rpm, set the temperature at 160-165°C in the feeding section, 180-190°C in the melting section, 200-210°C in the mixing section, 190-200°C in the die, and a die vacuum of <500 Pa. S9-3: Cooling and molding by an injection molding machine, with the barrel temperature set to 190-210°C, the mold temperature to 60-80°C, the injection pressure to 80-120 MPa, the holding time to 10-15 s, and the cooling time to 20-30 s, to obtain the glass fiber reinforced polyurethane composite material.

[0013] As a preferred technical solution of the present invention, the melt pressure in S9-2 is controlled to be 8~10 MPa.

[0014] Chopped glass fibers construct an isotropic reinforcement network through a three-dimensional random distribution. Their random orientation characteristics can effectively prevent cracks from extending in a single direction, significantly improving the warpage resistance of the composite material and reducing the flatness error of the product. Continuous glass fibers are oriented along the direction of force, forming a longitudinal stress conduction skeleton, and their tensile strength is significantly improved compared to a pure polyurethane matrix. When chopped glass fibers and continuous glass fibers are mixed in a mass ratio of (2-3):1, the agglomeration index is significantly reduced compared to pure chopped glass fibers, forming a skeleton-matrix dual-continuous phase structure. The continuous glass fibers bear the main load, while the chopped glass fibers fill the matrix pores and inhibit crack extension, significantly improving the yield strength of the polyurethane matrix.

[0015] A mixture of chopped glass fibers and continuous glass fibers is placed in a mixed plasma with an argon and oxygen ratio of 5:1 by volume. By optimizing the concentration of O2* radicals, a micro-nanoscale concave-convex structure is formed on the glass fiber surface, significantly increasing the specific surface area and significantly enhancing mechanical meshing. This effectively increases the oxygen content on the glass fiber surface, introducing polar groups and thus increasing the surface energy of the glass fiber. Furthermore, by controlling the energy input power of the plasma, the surface activation depth is guaranteed to reach 5-10 nm while avoiding excessive etching that would otherwise lead to loss of glass fiber strength.

[0016] Plasma-treated glass fibers are placed in a nano-silica sol to create a coating effect. The silanol groups on the nano-silica surface form covalent bonds with the activated sites on the glass fiber surface and the polyurethane isocyanate groups, significantly improving the interfacial shear strength. The formation of a nano-silica transition layer of appropriate thickness can effectively alleviate interfacial stress concentration, significantly improving the impact toughness and heat resistance of the composite material. Furthermore, the silane coupling agent, acting as an interfacial modifier, synergizes with the nano-silica particles on the surface of the modified glass fiber, significantly reducing the polarity difference between the glass fiber and the polyurethane matrix, reducing glass fiber agglomeration, and further improving the dispersion uniformity of the glass fiber in the polyurethane matrix.

[0017] Furthermore, in glass fiber-reinforced polyurethane composites, antioxidants can effectively inhibit the thermal oxidative degradation of the polyurethane matrix by capturing free radicals and decomposing hydroperoxides. This helps maintain the stability of the silane coupling agent-modified interface, slowing material aging while also improving color stability and ensuring long-term performance and appearance. Lubricants significantly improve processing fluidity, reducing friction between the melt, glass fiber, and equipment, lowering processing energy consumption and equipment wear, and optimizing product surface quality. Lubricants also promote uniform dispersion of glass fiber, synergizing with silane coupling agents to enhance reinforcement efficiency, improve demolding properties, and shorten molding cycles. These two agents, combined with silane coupling agents, create a synergistic effect, achieving a balance between processing stability and product performance while controlling costs.

[0018] Beneficial effects of the present invention: The present invention mixes chopped glass fibers with continuous glass fibers in a mass ratio of (2~3): 1 to construct a synergistic reinforcement system of a three-dimensional disordered reinforcement network and a directional stress conduction skeleton, significantly improving the material's anti-warping performance and longitudinal tensile strength. Surface activation treatment of the glass fiber is performed using an argon-oxygen volume ratio of 5: 1 plasma. A micro-nano concave-convex structure of 5~10nm depth is formed under controlled energy input power, polar groups are introduced simultaneously to increase surface energy, and a nano-silica sol coating process is used to form a covalently bonded silane coupling agent-nano-silica composite transition layer on the glass fiber surface. The interface shear strength is significantly improved, and the composite interface structure effectively alleviates stress concentration, effectively improving the material's impact toughness and heat-resistant temperature. In addition, the antioxidant added in the formula works synergistically with the lubricant to optimize processing fluidity while suppressing thermal oxidative degradation, reduce the glass fiber dispersion coefficient, and significantly outperform the traditional glass fiber reinforced polyurethane system in comprehensive mechanical properties and molding quality. DETAILED DESCRIPTION

[0019] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0020] In the Examples of the present invention and the Comparative Examples: Chopped glass fiber: purchased from Chongqing Composite Materials Co., Ltd. Continuous glass fiber: purchased from Chongqing Composite Materials Co., Ltd. Thermoplastic polyurethane: purchased from Univar Chemicals (Shanghai) Co., Ltd. Nano-silica sol: purchased from Lianyungang Huayuan Chemical Co., Ltd. Zinc stearate: purchased from Shandong Huishengtang Biopharmaceutical Co., Ltd. Ethylene bisstearamide: purchased from Jining Chengrun New Material Technology Co., Ltd. Silane coupling agents KH-550, KH-560, and KH-570 were purchased from Jiangxi Hongbai New Materials Co., Ltd. Antioxidant 1010: purchased from Guangzhou Dayin New Materials Co., Ltd. Antioxidant 1076: purchased from Qingdao Zhenguang Functional Materials Technology Co., Ltd. Antioxidant 264: purchased from Shandong Boshiwen New Materials Co., Ltd.

[0021] Example 1 A glass fiber reinforced polyurethane composite material, wherein the glass fiber reinforced polyurethane composite material formula 1 is as follows: calculated by weight, 60-80 parts of thermoplastic polyurethane, 15-25 parts of modified glass fiber, 2-5 parts of silane coupling agent KH-550, 1-2 parts of antioxidant 1010, and 1-3 parts of zinc stearate; Wherein, the preparation method of the modified glass fiber is as follows: S1-1: Chopped glass fibers and continuous glass fibers were mixed in a mass ratio of 2.5:1 and then plasma treated for 70 s in a plasma atmosphere of argon and oxygen in a volume ratio of 5:1. The plasma power was 250 W, the electrode spacing was 110 mm, and the vacuum degree was 70 Pa to obtain pretreated glass fibers. S1-2: 15 parts by weight of pretreated glass fiber were added to 85 parts by weight of nano-silica sol, wherein the particle size of the silica sol in the nano-silica sol was 20 nm and the solid content in the sol was 15%. The mixture was ultrasonically mixed for 75 minutes at a power of 120 W and a temperature of 40°C. The mixture was then washed with deionized water and vacuum dried at 120°C for 14 hours to obtain the modified glass fiber.

[0022] A preparation process of a glass fiber reinforced polyurethane composite material, the specific steps of the preparation process are as follows: S9-1: Modified glass fiber and silane coupling agent KH-550 were mixed according to the ratio of Formula 1 for 8 minutes at a mixing speed of 850 rpm. Then, thermoplastic polyurethane, antioxidant 1010 and zinc stearate were added in sequence and mixed for a further 15 minutes at a mixing speed of 650 rpm to obtain a premix; S9-2: The premix was added to a twin-screw extruder with a screw speed of 400 rpm. The temperatures were set at 162°C in the feeding section, 185°C in the melting section, 205°C in the mixing section, and 195°C in the die. The melt pressure was controlled at 9 MPa, and the die vacuum was <500 Pa. S9-3: Cooling molding is performed by an injection molding machine with the barrel temperature set to 200°C, the mold temperature to 70°C, the injection pressure to 100 MPa, the holding time to 12 s, and the cooling time to 25 s to obtain the glass fiber reinforced polyurethane composite material.

[0023] Example 2 A glass fiber reinforced polyurethane composite material, wherein the glass fiber reinforced polyurethane composite material formula 2 is as follows: calculated by weight, 60 parts of thermoplastic polyurethane, 15 parts of modified glass fiber, 2 parts of silane coupling agent KH-560, 1 part of antioxidant 264, and 1 part of ethylene bisstearamide; Wherein, the preparation method of the modified glass fiber is as follows: S1-1: Chopped glass fibers and continuous glass fibers were mixed in a mass ratio of 2:1 and then plasma treated for 60 s in a plasma atmosphere consisting of a mixture of argon and oxygen in a volume ratio of 4:1. The plasma power was 200 W, the electrode spacing was 100 mm, and the vacuum level was 50 Pa to obtain pretreated glass fibers. S1-2: 10 parts by weight of pretreated glass fiber were added to 80 parts by weight of nano-silica sol, wherein the particle size of the silica sol in the nano-silica sol was 20 nm and the solid content in the sol was 10%. The mixture was ultrasonically mixed for 60 minutes at an ultrasonic power of 100 W and a temperature of 35°C. The mixture was then washed with deionized water and vacuum dried at 120°C for 12 hours to obtain the modified glass fiber.

[0024] A preparation process of a glass fiber reinforced polyurethane composite material, the specific steps of the preparation process are as follows: S9-1: Modified glass fiber and silane coupling agent KH-560 were mixed according to the ratio of Formula 2 for 5 minutes at a mixing speed of 800 rpm. Thermoplastic polyurethane, antioxidant 264, and lubricant were then added in sequence and mixed for a further 10 minutes at a mixing speed of 600 rpm to obtain a premix. S9-2: The premix was added to a twin-screw extruder with a screw speed of 300 rpm, a feeding zone temperature of 160°C, a melting zone temperature of 180°C, a mixing zone temperature of 200°C, and a die temperature of 190°C. The melt pressure was controlled at 8 MPa, and the die vacuum was <500 Pa. S9-3: Cooling and molding by an injection molding machine, with the barrel temperature set to 190°C, the mold temperature to 60°C, the injection pressure to 80 MPa, the holding time to 10 s, and the cooling time to 20 s, to obtain the glass fiber reinforced polyurethane composite material.

[0025] Example 3 A glass fiber reinforced polyurethane composite material, wherein the glass fiber reinforced polyurethane composite material formula 3 is as follows: calculated by weight, 80 parts of thermoplastic polyurethane, 25 parts of modified glass fiber, 5 parts of silane coupling agent KH-570, 2 parts of antioxidant 1076, and 3 parts of zinc stearate; Wherein, the preparation method of the modified glass fiber is as follows: S1-1: Chopped glass fibers and continuous glass fibers were mixed in a mass ratio of 3:1 and then plasma treated for 80 s in a plasma atmosphere consisting of a mixture of argon and oxygen in a volume ratio of 6:1. The plasma power was 300 W, the electrode spacing was 120 mm, and the vacuum level was 100 Pa to obtain pretreated glass fibers. S1-2: 20 parts by weight of pretreated glass fiber were added to 90 parts by weight of nano-silica sol, wherein the particle size of the silica sol in the nano-silica sol was 20 nm and the solid content in the sol was 20%. The mixture was ultrasonically mixed for 90 minutes at a power of 150 W and a temperature of 45°C. The mixture was then washed with deionized water and vacuum dried at 120°C for 16 hours to obtain the modified glass fiber.

[0026] A preparation process of a glass fiber reinforced polyurethane composite material, the specific steps of the preparation process are as follows: S9-1: Modified glass fiber and silane coupling agent KH-570 were mixed according to the ratio of Formula 3 for 10 minutes at a mixing speed of 900 rpm. Thermoplastic polyurethane, antioxidant 1076, and zinc stearate were then added in sequence and mixed for a further 20 minutes at a mixing speed of 700 rpm to obtain a premix. S9-2: The premix was added to a twin-screw extruder with a screw speed of 500 rpm, a feeding zone temperature of 165 °C, a melting zone temperature of 190 °C, a mixing zone temperature of 210 °C, a die temperature of 200 °C, a melt pressure of 10 MPa, and a die vacuum of <500 Pa. S9-3: Cooling and molding by an injection molding machine, with the barrel temperature set to 210°C, the mold temperature to 80°C, the injection pressure to 120 MPa, the holding time to 15 s, and the cooling time to 30 s, to obtain the glass fiber reinforced polyurethane composite material.

[0027] Comparative Example 1 Only chopped glass fibers were used in the preparation of the modified glass fibers, and the remaining steps were the same as those in Example 1.

[0028] Comparative Example 2 Only continuous glass fiber was used in the preparation of the modified glass fiber, and the remaining steps were the same as those in Example 1.

[0029] Comparative Example 3 Nano-silica sol was not added during the preparation of the modified glass fiber, and the remaining steps were the same as those in Example 1.

[0030] Comparative Example 4 The modified glass fiber was prepared without plasma treatment, and the remaining steps were the same as in Example 1.

[0031] Comparative Example 5 Only the chopped glass fibers and the continuous glass fibers were mechanically mixed at a mass ratio of 2.5:1, and the remaining steps were the same as in Example 1.

[0032] Performance Testing The tensile strength of the composite materials prepared in the Examples and Comparative Examples was tested according to ASTM D638 using a universal testing machine at a tensile rate of 50 mm / min. The impact strength of the composite materials prepared in the Examples and Comparative Examples was tested according to ASTM D256 using a notched impact tester with a pendulum energy of 4 J and a notch depth of 2.5 mm. The experimental results are summarized in the following table.

[0033] It can be seen from the data of the examples and comparative examples that the composite material prepared in the present invention has excellent mechanical properties.

[0034] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A glass fiber reinforced polyurethane composite material, characterized in that: The glass fiber reinforced polyurethane composite material has the following formula: calculated by weight, 60-80 parts of thermoplastic polyurethane, 15-25 parts of modified glass fiber, 2-5 parts of interface modifier, 1-2 parts of antioxidant, and 1-3 parts of lubricant; Wherein, the preparation method of the modified glass fiber is as follows: S1-1: Chopped glass fibers were mixed with continuous glass fibers and then treated with plasma for 60-80 s in a plasma atmosphere of argon and oxygen in a volume ratio of 4-6:1 to obtain pretreated glass fibers. S1-2: 10-20 parts by weight of pretreated glass fiber are added to 80-90 parts by weight of nano-silica sol, ultrasonically mixed for 60-90 minutes, then washed with deionized water and vacuum dried at 120° C. for 12-16 hours to obtain the modified glass fiber.

2. The glass fiber reinforced polyurethane composite material according to claim 1, characterized in that: The chopped glass fibers and the continuous glass fibers in S1-1 are mixed in a mass ratio of (2-3):

1.

3. The glass fiber reinforced polyurethane composite material according to claim 1, characterized in that: The interface modifier is one or more of the silane coupling agents KH-550, KH-560, and KH-570.

4. The glass fiber reinforced polyurethane composite material according to claim 1, characterized in that: The plasma power in S1-1 is 200-300 W, the electrode spacing is 100-120 mm, and the vacuum degree is 50-100 Pa.

5. The glass fiber reinforced polyurethane composite material according to claim 1, characterized in that: The particle size of the nano-silica sol in S1-2 is 20 nm, and the solid content of the sol is 10-20%.

6. The glass fiber reinforced polyurethane composite material according to claim 1, characterized in that: The power of the ultrasound in S1-2 is 100-150 W, and the temperature of the ultrasound is 35-45°C.

7. The glass fiber reinforced polyurethane composite material according to claim 1, characterized in that: The antioxidant is one or more of antioxidant 1010 , antioxidant 264 and antioxidant 1076 .

8. The glass fiber reinforced polyurethane composite material according to claim 1, characterized in that: The lubricant is one or a combination of zinc stearate and ethylene bisstearamide.

9. A process for preparing the glass fiber reinforced polyurethane composite material according to any one of claims 1 to 8, characterized in that: The specific steps of the preparation process are as follows: S9-1: The modified glass fiber and the interfacial modifier were mixed according to the formula ratio for 5-10 minutes at a mixing speed of 800-900 rpm. The thermoplastic polyurethane, antioxidant, and lubricant were then added in sequence and further mixed for 10-20 minutes at a mixing speed of 600-700 rpm to obtain a premix. S9-2: Add the premix to a twin-screw extruder with a screw speed of 300-500 rpm, set the temperature at 160-165°C in the feeding section, 180-190°C in the melting section, 200-210°C in the mixing section, 190-200°C in the die, and a die vacuum of <500 Pa; S9-3: Cooling and molding by an injection molding machine, with the barrel temperature set to 190-210°C, the mold temperature to 60-80°C, the injection pressure to 80-120 MPa, the holding time to 10-15 s, and the cooling time to 20-30 s, to obtain the glass fiber reinforced polyurethane composite material.

10. The process for preparing a glass fiber reinforced polyurethane composite material according to claim 9, characterized in that: The melt pressure in S9-2 is controlled to be 8-10 MPa.

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