High-strength creep-resistant long fiber reinforced polypropylene composite material for automobile and preparation method of high-strength creep-resistant long fiber reinforced polypropylene composite material

Abstract

The invention discloses a high-strength creep-resistant long fiber reinforced polypropylene composite material for an automobile and a preparation method of the high-strength creep-resistant long fiber reinforced polypropylene composite material. The invention relates to a high-strength creep-resistant long fiber reinforced polypropylene composite material for automobiles, which mainly comprises 5-30 parts of continuous long carbon fiber, 5-30 parts of long glass fiber, 0.2-5.0 parts of antioxidant and toner, and the balance of polypropylene (PP) resin. The problem that the fiber retention length of the continuous long carbon fiber / continuous long glass fiber in the material is short in the continuous long carbon fiber / continuous long glass fiber integrated composite extrusion process is effectively solved through optimization of a polypropylene material formula modification processing technology and combination of processing extrusion equipment and a process optimization and improvement technology for the first time; and meanwhile, the dispersion and combination problem among the glass fiber / carbon fiber / polypropylene matrix is also ensured. The high-performance fiber-reinforced polypropylene composite material with high strength and good creep resistance is prepared while the comprehensive cost advantage is considered, so that the increasing requirements of high performance and light weight by replacing steel with plastic in the automobile industry are met.

Description

Technical Field

[0001] The invention relates to the field of fiber-reinforced polypropylene composite materials, and in particular to a high-strength creep-resistant long-fiber-reinforced polypropylene composite material for automobiles and a preparation method thereof. Background Art

[0002] Long fiber reinforced polypropylene material itself has the advantages of light weight, high strength, high rigidity, good impact resistance, excellent low temperature performance and good dimensional stability. In practical applications, it is often used to replace engineering plastics and even metal materials. In recent years, with the development trend of lightweight automobiles, long fiber reinforced polypropylene composite materials have been favored by the automotive industry and are widely used to make instrument panels, all-plastic tailgates, front engine compartment covers, etc. It is a model of replacing steel with plastic, energy saving and low carbon. Automobile structural parts not only need to pass a series of high-strength mechanical performance tests, but also examine the creep resistance of the parts by simulating the long-term stress conditions during actual use. This performance is one of the key factors to protect the safety of passengers and extend the service life of the car. Therefore, keeping up with the material demand to develop ultra-high strength, creep-resistant long fiber reinforced polypropylene composite materials can meet the increasingly stringent requirements of the automotive industry.

[0003] In recent years, some progress has been made in long fiber reinforced polypropylene composite materials. For example, invention patents CN104341680A and CN106589579A disclose a dimensionally stable and creep-resistant long glass fiber reinforced polypropylene composite material and a preparation method thereof. By adding a nucleating agent or a filler modifier to cooperate with the long glass fiber, the common warping phenomenon of the long glass fiber reinforced polypropylene material is alleviated, and the dimensional stability of the material is improved. The disadvantage is that the strength of the prepared material is insufficient, especially the tensile strength and bending strength representing the strength and rigidity of the material.

[0004] In order to further enhance the mechanical properties and creep resistance of long glass fiber reinforced polypropylene materials, invention patent CN116041752A discloses a long glass fiber and long carbon fiber composite reinforced polypropylene material and its preparation method, which mainly prepares long glass fiber reinforced creep resistant polypropylene material by compounding long carbon fiber and long glass fiber with polypropylene material through conventional melt impregnation process. This method does not clearly disclose how to pull long carbon fiber and long glass fiber out from an impregnation grinding mouth and how to ensure the mixing uniformity between glass fiber and carbon fiber. In addition, it is limited by the complexity and high cost of the melt impregnation process, which becomes the main obstacle to subsequent large-scale application.

[0005] To this end, invention patent CN117700873A discloses a long glass fiber and long carbon fiber composite reinforced polypropylene material and a preparation method thereof. The method uses a conventional extrusion granulation processing method to directly feed glass / carbon fiber longer short fibers and some other filler components into the extrusion granulation process. The process does not retain the fiber length, and the compatibility of carbon / glass fiber / polypropylene resin is not optimized and improved, resulting in the prepared material having low strength and failing to meet the true enhancement modification expectations, and failing to meet the use requirements of related high-strength creep-resistant components.

[0006] In addition, Chinese invention patent CN115785569A discloses a carbon fiber reinforced polypropylene composite material and its preparation method. The prepared material has high mechanical properties, but no technical improvement has been made to the retention length of the carbon fiber in the material, and the creep performance of the material cannot be ensured. In addition, the cost of carbon fiber is much higher than that of inorganic fibers such as glass fiber, which also lays many hidden dangers and obstacles for its subsequent large-scale industrial application.

[0007] In the engineering field, in order to retain the fiber length for a long time, long fiber reinforced polypropylene composite materials generally adopt the direct feeding method, which is made by impregnating continuous fibers with plastic melt, pultruding and granulating. This is currently a more commonly used solution to maintain the fiber retention length. However, this method has the disadvantages of high process complexity, low output, high manufacturing cost and easy to cause uneven mixing of resin matrix and fiber.

[0008] Therefore, in order to solve the above problems, a fiber-reinforced polypropylene composite material that takes into account product cost and meets ultra-high strength creep resistance is prepared and developed. The present invention team starts from the development needs of the industry to which it belongs, optimizes the polypropylene material formula modification processing technology, and combines the processing extrusion equipment and process optimization to form a long carbon fiber / long glass fiber integrated composite extrusion technology, which effectively solves the fiber retention length of the long carbon fiber / long glass fiber in the material while also ensuring the dispersion and bonding problem between the glass fiber / carbon fiber / polypropylene matrix, and prepares a high-performance fiber-reinforced polypropylene composite material with high strength and good creep resistance under the premise of considering the comprehensive cost advantage. It is of great significance to improve the performance of fiber-reinforced polypropylene materials and broaden their application in the automotive industry. Summary of the invention

[0009] The purpose of the present invention is to overcome the deficiencies of the prior art, provide a high-strength creep-resistant long fiber reinforced polypropylene composite material for automobiles and a preparation method thereof, in order to increase the carbon / glass fiber retention length in the composite material after mixing and shearing by a twin-screw extruder, the relevant engineering and technical personnel of the present invention team first use continuous long glass fiber and continuous long carbon fiber to feed the twin-screw extruder in a certain proportion by side feeding, and optimize the arrangement and combination of the extruder screws to reduce the shear damage of the twin-screw extruder to the fiber during the material extrusion process. At the same time, in order to improve the shear strength reduction caused by the adjustment of the screw combination and further enhance the mixing performance of the long glass fiber and the long carbon fiber with the polypropylene matrix, the patent of the present invention introduces a set of reverse thread shearing modules in the screw assembly of the extrusion equipment, which effectively solves the fiber retention length of the long carbon fiber / long glass fiber in the material while also ensuring the dispersion and bonding problem between the glass fiber / carbon fiber / polypropylene matrix. The specific implementation mainly includes the following technical solutions.

[0010] A high-strength creep-resistant long fiber reinforced polypropylene composite material for automobiles is prepared by feeding polypropylene, continuous long carbon fiber, continuous long glass fiber and related processing modification additives into a twin-screw extruder for blending and extrusion in a certain proportion by direct side feeding, and is composed of the following raw materials in parts by weight:

[0011] Continuous long carbon fiber: 5-40 parts;

[0012] Continuous long glass fiber: 10-40 parts;

[0013] Compatibilizer: 3-5 parts;

[0014] Antioxidant: 1-5 parts;

[0015] Polypropylene resin: balance.

[0016] The polypropylene resin is conventional polypropylene, and the melt flow rate of the polypropylene is 10-80 g / 10 min under the test conditions of 230° C. and 2.16 kg. Preferably, the conventional polypropylene is high-rigidity homopolymer polypropylene, and its melt flow rate is in the range of 10-80 g / 10 min.

[0017] The continuous long carbon fiber is a surface-treated long carbon fiber with a sizing agent content of 2-10% and a fiber diameter of 5-15 μm. Preferably, the T700 series continuous long carbon fiber produced by Shanghai Petrochemical or Toray is used;

[0018] The glass fiber is a surface treated long glass fiber with a sizing agent content of 2-10% and a diameter of 5-25 μm. Preferably, the glass fiber is a continuous alkali-free glass fiber with a fiber diameter of 5-15 μm, preferably a 2400dtex series continuous long glass fiber of Jushi, Chongqing glass fiber, or OC glass fiber.

[0019] The compatibilizer is selected from one or more combinations of maleic anhydride and its derivatives, epoxies, carboxylates and acrylic acid glycidol. Preferably, the compatibilizer has a melt flow rate of 0.05 to 1000 g / 10 min and a grafting rate of 0.05 to 3%. More preferably, the compatibilizer is grafted polypropylene, with a melt flow rate of 100 to 800 g / 10 min and a grafting rate of 0.5 to 3%.

[0020] The antioxidant can be selected from hindered phenols, phosphites, amines, etc., preferably one or more of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester, tris[2,4-di-tert-butylphenyl] phosphite, 2,6-di-tert-butyl-4-methylphenol, and bis(3,5-di-tert-butyl-4-hydroxyphenyl) sulfide.

[0021] In some embodiments of the present invention, the preparation process and method involved are: long carbon fiber and long glass fiber are directly fed into a twin-screw extruder. On the one hand, in order to reduce the damage of the screw shearing to the carbon / glass fiber during the twin-screw extrusion process and further increase the retention length of the carbon / glass fiber in the modified material, the shear strength and shear arrangement of the twin-screw conveying screw are appropriately adjusted and optimized. On the other hand, a reverse shear module is introduced into the extrusion screw in an innovative way to ensure that the fiber and the polypropylene resin can be fully mixed and uniform. Therefore, by introducing a reverse shear module and appropriately weakening and optimizing the shearing effect of the screw, the molten polypropylene resin can be fully mixed with the long glass fiber and the long carbon fiber without affecting the retention length of the fiber, so as to achieve the effect of improving the compatibility between carbon fiber, glass fiber and PP resin, and further improve the mechanical and creep resistance of the composite material.

[0022] Polypropylene raw materials, compatibilizers and related antioxidant additives are fed into the twin-screw extruder through the main feeding port, and long carbon fiber / long glass fiber is directly fed into the extruder through the side feeding port.

[0023] Furthermore, the present invention introduces a set of reverse conveying modules while appropriately adjusting the shearing action of the screw to increase the retention length of the carbon / glass fiber in the modified material while allowing the molten polypropylene resin to be fully mixed with the long glass fiber and the long carbon fiber. The present invention uses 30°, 45°, 60°, and 90° shear block combinations, and compares the effects of different shear strengths on material properties to explore the appropriate shear strength.

[0024] The present invention achieves the purpose of controlling the full melting and mixing of the fiber and the PP resin by adjusting the shearing and conveying section screws in the twin-screw extruder and the introduced reverse shearing module, while ensuring the fiber length in the composite material. The specific combination is shown in the following table:

[0025]

[0026]

[0027] Note: The larger the angle of the shear module, the stronger the shearing; the larger the angle of the return conveying module, the stronger the conveying capacity.

[0028] The relevant combined fiber retention length and related compatibility (impact performance & number of fiber agglomerations on the sample surface) are shown in the following table, among which the preferred combination 8 is the preferred solution of the present invention:

[0029]

[0030] The specific test method is as follows:

[0031] The fiber retention length is obtained by using an optical microscope to test the length of the residual fibers after the modified particles are burned.

[0032] The notched impact strength was obtained by preparing and testing the prepared modified material according to the requirements of ISO179-1. The number of fiber agglomerates was obtained by injection molding the prepared fiber-reinforced polypropylene material into a 150*100*3.2 mm sample and counting the number of undispersed fiber agglomerates on the sample.

[0033] Furthermore, in some embodiments of the present invention, the preparation method of the PP / LGF / LCF composite material is as follows: the PP, compatibilizer, and antioxidant are fed from the main feeding port of the co-rotating parallel twin-screw extruder, and the long carbon fiber and long glass fiber are fed from the side feeding port. The materials are transported to the die under the transmission of the twin screws, and the PP / LGF / LCF composite material is obtained after extrusion, cooling, drying, and pelletizing.

[0034] Preferably, in some embodiments of the present invention, the preparation method of the PP / LGF / LCF composite material is: after the PP resin, antioxidant and compatibilizer are evenly mixed, the main feed from the co-rotating parallel twin-screw extruder is added into the twin-screw extruder at 200-250°C, and the vacuum degree is maintained at -0.1-0MPa. At the same time, the long glass fiber and long carbon fiber are side-fed into the twin-screw extruder at a speed of 50-150rpm. Under the action of the reverse shear module and heat, the PP resin, the long glass fiber, the long carbon fiber and the compatibilizer are fully melted and mixed, and then extruded through the die, cooled, dried and pelletized to obtain a high-strength creep-resistant PP / LGF / LCF composite material.

[0035] Compared with the prior art, the advantages of the present invention are as follows:

[0036] (1) The present invention provides a high-strength, creep-resistant long fiber reinforced polypropylene composite material for automobiles and a preparation method thereof, which effectively solves the problems of poor dispersion of conventional glass fiber and carbon fiber in the PP matrix, low interface compatibility, and poor mechanical properties and creep resistance of the PP / LGF / LCF composite material. While considering the comprehensive cost advantage, a high-performance fiber reinforced polypropylene composite material with high strength and good creep resistance is prepared, which is of great significance for improving the performance of fiber reinforced polypropylene materials and broadening their application in the automotive industry.

[0037] (2) In addition to providing a high-strength, creep-resistant long fiber reinforced polypropylene composite material for automobiles and a preparation method thereof, the present invention also effectively solves the problem of the fiber retention length of the continuous long carbon fiber / continuous long glass fiber in the continuous long carbon fiber / continuous long glass fiber integrated composite extrusion process for the first time by combining processing extrusion equipment with process optimization and improvement technology, while also ensuring the dispersion and bonding between the glass fiber / carbon fiber / polypropylene matrix, thereby providing a set of practical and effective solutions for the continuous long carbon fiber / continuous long glass fiber integrated composite extrusion process. This solution is not limited to the preparation method of the high-strength, creep-resistant long fiber reinforced polypropylene composite material for automobiles of the present invention, and can also be applied to other continuous long fiber reinforced material systems. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. Additional aspects and advantages of the present invention will be partially given in the following description, and part will be more obvious from the following description. It should be noted that the following description is only used to explain the present invention, but is not intended to limit the present invention.

[0039] The polypropylene raw material in the following examples is preferably a polypropylene resin of grade PP-iPP-M60T produced by Zhenhai Petrochemical, and the melt flow rate of the material is 60g / 10min at 230°C and 2.16Kg.

[0040] The long glass fiber is 2400dtex long glass fiber produced by Jushi Fiberglass.

[0041] The long carbon fiber is T7001650dtex long carbon fiber produced by Shanghai Petrochemical.

[0042] The screw / reverse conveying module combinations 1 to 6 are as shown in the product instructions.

[0043] Example 1

[0044] 56 parts of PP, antioxidant (0.3 parts and 0.2 parts of antioxidant 1010 and 168 respectively), 0.5 parts of black masterbatch, and 3 parts of compatibilizer PP-g-MAH were mixed evenly and added to the twin-screw extruder from the main feeding port, 40 parts of continuous long glass fiber were fed from the side feeding port at a speed of 100rpm, and the combination of screw / reverse shear module 5 to 8 was extruded for granulation and injection molding to prepare standard specimens. Among them, the extrusion melt blending temperature was 230°C, and the extrusion vacuum was opened and the vacuum degree was maintained at -0.08MPa.

[0045] Example 2

[0046] 56 parts of PP, antioxidant (0.3 parts and 0.2 parts of antioxidant 1010 and 168 respectively), 0.5 parts of black masterbatch, and 3 parts of compatibilizer PP-g-MAH were mixed evenly and added to the twin-screw extruder from the main feeding port, 35 parts of long glass fiber and 5 parts of long carbon fiber were fed from the side feeding port at a speed of 100rpm, and the combination of screw / reverse shear module 5 to 8 was extruded for granulation and injection molding to prepare standard specimens. Among them, the extrusion melt blending temperature was 230°C, and the extrusion vacuum was opened and the vacuum degree was maintained at -0.08MPa.

[0047] Example 3

[0048] 56 parts of PP, antioxidant (0.3 parts and 0.2 parts of antioxidant 1010 and 168 respectively), 0.5 parts of black masterbatch, and 3 parts of compatibilizer PP-g-MAH were mixed evenly and added to the twin-screw extruder from the main feeding port, 30 parts of long glass fiber and 10 parts of long carbon fiber were fed from the side feeding port at a speed of 100rpm, and the combination of screw / reverse shear module 5 to 8 was extruded for granulation and injection molding to prepare standard specimens. Among them, the extrusion melt blending temperature was 230°C, and the extrusion vacuum was opened and the vacuum degree was maintained at -0.08MPa.

[0049] Example 4

[0050] 56 parts of PP, antioxidant (0.3 parts and 0.2 parts of antioxidant 1010 and 168 respectively), 0.5 parts of black masterbatch, and 3 parts of compatibilizer PP-g-MAH were mixed and added to the twin-screw extruder from the main feed port, 20 parts of long glass fiber and 20 parts of long carbon fiber were fed from the side feed port at a speed of 100rpm, and the combination of screw / reverse shear module 5-8 was extruded for granulation and injection molding to prepare standard specimens. Among them, the extrusion melt blending temperature was 230°C, and the extrusion vacuum was opened and the vacuum degree was maintained at -0.08MPa.

[0051] Example 5

[0052] 56 parts of PP, antioxidant (0.3 parts and 0.2 parts of antioxidant 1010 and 168 respectively), 0.5 parts of black masterbatch, and 3 parts of compatibilizer PP-g-MAH were mixed evenly and added to the twin-screw extruder from the main feeding port, 10 parts of long glass fiber and 30 parts of long carbon fiber were fed from the side feeding port at a speed of 100rpm, and the combination of screw / reverse shear module 5-8 was extruded for granulation and injection molding to prepare standard specimens. Among them, the extrusion melt blending temperature was 230°C, and the extrusion vacuum was opened and the vacuum degree was maintained at -0.08MPa.

[0053] Example 6

[0054] 56 parts of PP, antioxidant (0.3 parts and 0.2 parts of antioxidant 1010 and 168 respectively), 0.5 parts of black masterbatch, and 3 parts of compatibilizer PP-g-MAH were mixed evenly and added to the twin-screw extruder from the main feeding port, 5 parts of long glass fiber and 35 parts of long carbon fiber were fed from the side feeding port at a speed of 100rpm, and the combination of screw / reverse shear module 5 to 8 was extruded for granulation and injection molding to prepare standard specimens. Among them, the extrusion melt blending temperature was 230°C, and the extrusion vacuum was opened and the vacuum degree was maintained at -0.08MPa.

[0055] Example 7

[0056] 56 parts of PP, antioxidant (0.3 parts and 0.2 parts of antioxidant 1010 and 168 respectively), 0.5 parts of black masterbatch, and 3 parts of compatibilizer PP-g-MAH were mixed evenly and added to the twin-screw extruder from the main feed port, 40 parts of long carbon fiber were fed from the side feed port at a speed of 100rpm, and the combination of screw / reverse shear module 5 to 8 was extruded for granulation and injection molding to prepare standard specimens. Among them, the extrusion melt blending temperature was 230°C, and the extrusion vacuum was opened and the vacuum degree was maintained at -0.08MPa.

[0057] Comparative Example 1

[0058] 56 parts of PP, antioxidant (0.3 parts and 0.2 parts of antioxidant 1010 and 168 respectively), 0.5 parts of black masterbatch, and 3 parts of compatibilizer PP-g-MAH were mixed evenly and added to the twin-screw extruder from the main feeding port, 40 parts of continuous long glass fiber were fed from the side feeding port at a speed of 100rpm, and the combination of screw / reverse shear module 1 to 4 was extruded for granulation and injection molding to prepare standard specimens. Among them, the extrusion melt blending temperature was 230°C, and the extrusion vacuum was opened and the vacuum degree was maintained at -0.08MPa.

[0059] Comparative Example 2

[0060] 56 parts of PP, antioxidant (0.3 parts and 0.2 parts of antioxidant 1010 and 168 respectively), 0.5 parts of black masterbatch, and 3 parts of compatibilizer PP-g-MAH were mixed and added to the twin-screw extruder from the main feed port, 35 parts of long glass fiber and 5 parts of long carbon fiber were fed from the side feed port at a speed of 100rpm, and the combination of screw / reverse shear module 1 to 4 was extruded and granulated, and injection molded to prepare standard specimens. Among them, the extrusion melt blending temperature was 230°C, and the extrusion vacuum was opened and the vacuum degree was maintained at -0.08MPa.

[0061] Comparative Example 3

[0062] 56 parts of PP, antioxidant (0.3 parts and 0.2 parts of antioxidant 1010 and 168 respectively), 0.5 parts of black masterbatch, and 3 parts of compatibilizer PP-g-MAH were mixed evenly and added to the twin-screw extruder from the main feeding port, 30 parts of long glass fiber and 10 parts of long carbon fiber were fed from the side feeding port at a speed of 100rpm, and the combination of screw / reverse shear module 1 to 4 was extruded and granulated, and injection molded to prepare standard specimens. Among them, the extrusion melt blending temperature was 230°C, and the extrusion vacuum was opened and the vacuum degree was maintained at -0.08MPa.

[0063] Comparative Example 4

[0064] 56 parts of PP, antioxidant (0.3 parts and 0.2 parts of antioxidant 1010 and 168 respectively), 0.5 parts of black masterbatch, and 3 parts of compatibilizer PP-g-MAH were mixed evenly and added to the twin-screw extruder from the main feeding port, 20 parts of long glass fiber and 20 parts of long carbon fiber were fed from the side feeding port at a speed of 100rpm, and the combination of screw / reverse shear module 1 to 4 was extruded for granulation and injection molding to prepare standard specimens. Among them, the extrusion melt blending temperature was 230°C, and the extrusion vacuum was opened and the vacuum degree was maintained at -0.08MPa.

[0065] Comparative Example 5

[0066] 56 parts of PP, antioxidant (0.3 parts and 0.2 parts of antioxidant 1010 and 168 respectively), 0.5 parts of black masterbatch, and 3 parts of compatibilizer PP-g-MAH were mixed evenly and added to the twin-screw extruder from the main feed port, 10 parts of long glass fiber and 30 parts of long carbon fiber were fed from the side feed port at a speed of 100rpm, and the combination of screw / reverse shear module 1 to 4 was extruded and granulated, and injection molded to prepare standard specimens. Among them, the extrusion melt blending temperature was 230°C, and the extrusion vacuum was opened and the vacuum degree was maintained at -0.08MPa.

[0067] Comparative Example 6

[0068] 56 parts of PP, antioxidant (0.3 parts and 0.2 parts of antioxidant 1010 and 168 respectively), 0.5 parts of black masterbatch, and 3 parts of compatibilizer PP-g-MAH were mixed evenly and added to the twin-screw extruder from the main feed port, 5 parts of long glass fiber and 35 parts of long carbon fiber were fed from the side feed port at a speed of 100rpm, and the combination of screw / reverse shear module 1 to 4 was extruded for granulation and injection molding to prepare standard specimens. Among them, the extrusion melt blending temperature was 230°C, and the extrusion vacuum was opened and the vacuum degree was maintained at -0.08MPa.

[0069] Comparative Example 7

[0070] 56 parts of PP, antioxidant (0.3 parts and 0.2 parts of antioxidant 1010 and 168 respectively), 0.5 parts of black masterbatch, and 3 parts of compatibilizer PP-g-MAH were mixed and added to the twin-screw extruder from the main feed port, 40 parts of long carbon fiber were fed from the side feed port at a speed of 100rpm, and the combination of screw / reverse shear module 1 to 4 was extruded and granulated, and injection molded to prepare standard specimens. Among them, the extrusion melt blending temperature was 230°C, and the extrusion vacuum was opened and the vacuum degree was maintained at -0.08MPa.

[0071] Performance Testing

[0072] The tensile strength of the material is tested according to GB / T1040.1-2006 at a speed of 5mm / min; the flexural modulus and flexural modulus are tested according to GB / T9341-2008 at a speed of 2mm / min and a span of 64mm; the notched impact strength is tested according to GB / T1043.1-2008, with a V-notch; the number of fiber agglomerates, the prepared fiber-reinforced polypropylene material is injection molded into a 150*100*3.2mm sample, and the number of undispersed fiber agglomerates on the sample is counted; the tensile creep properties of the material are in accordance with GB / T41061-2021: Test method for creep properties of fiber-reinforced plastics; the fiber retention length is obtained by using an optical microscope to test the length of the residual glass fiber after the modified particles are burned.

[0073] Table 1 Performance evaluation of materials prepared in Examples 1-7 and Comparative Examples 1-7

[0074]

[0075]

[0076] Table 1 shows the performance evaluation results of the materials prepared in Examples 1-7 and Comparative Examples 1-7. The following conclusions are drawn from the analysis results:

[0077] (1) By analyzing the material properties of the screw / reverse shear module combinations 1-2 and 5-8 in the examples and comparative examples, it was found that the introduction of the reverse conveying module helps to improve the dispersion and bonding problems between the glass fiber / carbon fiber / polypropylene matrix. The impact strength of the material corresponding to the addition of the reverse conveying module is significantly increased, and the number of fiber agglomerations is significantly reduced.

[0078] (2) By comparing the mechanical properties and creep performance data of the materials of Examples 1-7 with those of Comparative Examples 1-7, it is shown that the mechanical properties and creep resistance of the modified materials after the processing extrusion equipment and the screw combination process are optimized are greatly improved. Among them, the continuous long glass fiber LGF / long carbon fiber LCF=30 / 10 material (Example 3, screw / reverse shear module combination 8) using the technical solution of the present invention has slightly better mechanical and creep resistance than the continuous long glass fiber LGF / long carbon fiber LCF=10 / 30 material (Example 5, screw / reverse shear module combination 1) which does not use the patented technical solution of the present invention. While effectively improving the mechanical properties of the material, it also greatly reduces the material cost. The prepared material has ultra-high mechanical properties and creep resistance.

Claims

1. A high-strength creep-resistant long fiber reinforced polypropylene composite material for automobiles, characterized in that: Prepared from raw materials in percentage by weight: Long carbon fiber: 5-40 parts; Long glass fiber: 10-40 parts; Compatibilizer: 3-5 parts; Antioxidant: 1-5 parts; Polypropylene resin: balance.

2. The high-strength creep-resistant long fiber reinforced polypropylene composite material for automobiles according to claim 1, characterized in that: The polypropylene resin is conventional polypropylene, and the melt flow rate of the polypropylene is 10-80 g / 10 min under the test conditions of 230° C. and 2.16 kg.

3. The high-strength creep-resistant long fiber reinforced polypropylene composite material for automobiles according to claim 2, characterized in that: The conventional polypropylene is a high-rigidity homopolymer polypropylene, and its melt flow rate is in the range of 10 to 80 g / 10 min.

4. The high-strength creep-resistant long fiber reinforced polypropylene composite material for automobiles according to claim 1, characterized in that: The continuous long carbon fiber is a surface-treated long carbon fiber with a sizing agent content of 2-10% and a fiber diameter of 5-15 μm.

5. The high-strength creep-resistant long fiber reinforced polypropylene composite material for automobiles according to claim 1, characterized in that: The glass fiber is a surface-treated long glass fiber with a sizing agent content of 2-10% and a diameter of 5-25 μm.

6. The high-strength creep-resistant long fiber reinforced polypropylene composite material for automobiles according to claim 5, characterized in that: The glass fiber is selected from continuous alkali-free glass fiber, and the fiber diameter is 5 to 15 μm.

7. The high-strength creep-resistant long fiber reinforced polypropylene composite material for automobiles according to claim 1, characterized in that: The compatibilizer is selected from one or a combination of maleic anhydride and its derivatives, epoxies, carboxylic acids and acrylic acid glycidol.

8. The high-strength creep-resistant long fiber reinforced polypropylene composite material for automobiles according to claim 7, characterized in that: The melt flow rate of the compatibilizer is 0.05-1000 g / 10 min, and the grafting rate is 0.05-3%.

9. The high-strength creep-resistant long fiber reinforced polypropylene composite material for automobiles according to claim 1, characterized in that: The antioxidant is selected from one or more of hindered phenols, phosphites and amines.

10. The high-strength creep-resistant long fiber reinforced polypropylene composite material for automobiles according to claim 9, characterized in that: The antioxidant is selected from one or more of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester, tris[2,4-di-tert-butylphenyl] phosphite, 2,6-di-tert-butyl-4-methylphenol, and bis(3,5-di-tert-butyl-4-hydroxyphenyl) sulfide.

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