High heat resistant and high rigidity polyolefin composite material and preparation method thereof

Abstract

This invention belongs to the field of polymer composite material modification technology, and particularly relates to a high heat-resistant and high-rigidity polyolefin composite material, comprising the following components by weight: 60-80 parts polypropylene resin, 15-30 parts surface-etched glass fiber, 5-15 parts sheet-like heat-resistant filler, 0-5 parts spherical auxiliary filler, 2-6 parts maleic anhydride-grafted polypropylene compatibilizer, 0.2-1 parts antioxidant, and 0.1-0.5 parts lubricant; the composite material has an alternating multilayer structure with a total of 2-128 layers, each layer having a thickness of 50-200 μm. This invention utilizes surface etching of glass fiber to construct a nanoporous structure, combined with coating with maleic anhydride-grafted polypropylene compatibilizer, forming a dual interfacial bonding mechanism of physical-mechanical interlocking and chemical bonding. This completely solves the problems of weak interfacial bonding and easy delamination at high temperatures caused by traditional coupling agents, significantly improving the material's interfacial stability and structural integrity.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite material modification technology, and particularly relates to a high heat-resistant and high-rigidity polyolefin composite material and its preparation method. Background Technology

[0002] Polypropylene (PP)-based polyolefin composites have been widely used in automotive structural parts, home appliance housings, rail transit interior parts, and outdoor engineering structural components due to their advantages such as low raw material cost, low density, good processing flowability, and recyclability. As downstream applications upgrade towards high-temperature service, high load support, and high-precision dimensions, the market has placed stringent comprehensive performance requirements on polyolefin composites: they must simultaneously possess excellent heat resistance, high rigidity, structural stability, and processing consistency to meet the needs of long-term high-temperature loads.

[0003] Existing glass fiber reinforced polyolefin modification technologies mostly employ conventional glass fiber surface treatment + single-screw / twin-screw co-extrusion processes. While these methods can improve material rigidity to some extent, four common technical bottlenecks across industries remain in industrial production and practical applications, severely restricting the large-scale application of these materials in high-end structural components: Insufficient interface bonding performance makes it difficult to synergistically improve heat resistance and rigidity. Traditional glass fibers are treated with only silane coupling agents and are bonded to the polypropylene matrix by weak chemical bonds without physical anchoring. Under high-temperature service conditions, the interface is prone to debonding and separation, which limits the improvement of the material's heat resistance and rigidity, and cannot meet the requirements of high-temperature and high-load conditions.

[0004] The processing technology severely damages the reinforcing phase, significantly reducing the reinforcing efficiency. Conventional blending processes employ a main feed method, coupled with high-shear screw elements. During the melt blending process, glass fibers are subjected to strong shearing, resulting in excessive breakage and a significant loss of effective reinforcement length. At the same time, the fibers cannot achieve directional arrangement, have low orientation, and poor load transfer efficiency, making it difficult to fully utilize the reinforcing advantages of glass fibers.

[0005] The reinforced structure is too simple, making it difficult to balance anisotropy and interlayer stability. Single glass fiber reinforced or sheet-like filler systems are prone to problems such as excessive material anisotropy and poor dimensional stability; ordinary blending processes cannot achieve layered directional arrangement of the reinforcing phase, resulting in poor balance between rigidity and heat resistance, and some systems may also have defects such as loose interlayer bonding and insufficient structural integrity.

[0006] Poor component dispersion and processing stability make it difficult to guarantee batch consistency. The single method of compatibilizer addition and unreasonable distribution can easily lead to uneven dispersion of inorganic fillers and poor interfacial compatibility. In continuous production, problems such as filler agglomeration, melt flow fluctuation, product warping and delamination are likely to occur, resulting in large batch performance differences and insufficient stability in industrial mass production.

[0007] To address the aforementioned issues, existing technologies have attempted to improve performance through optimizing coupling agent systems, modifying screw structures, and compounding fillers. However, these are all improvements using single technical means and cannot achieve synergistic optimization from multiple dimensions such as interface, structure, process, and dispersion. Therefore, they fail to fundamentally solve the industry challenges of balancing heat resistance and rigidity in polyolefin composites, such as significant damage to the reinforcing phase, poor structural stability, and low processing consistency. Thus, developing a polyolefin composite material that combines high heat resistance, high rigidity, structural stability, and controllable processing has become a pressing issue for those skilled in the art. Summary of the Invention

[0008] The purpose of this invention is to address the aforementioned technical problems by providing a high heat-resistant and high-rigidity polyolefin composite material and its preparation method.

[0009] In view of this, the present invention provides a high heat-resistant and high-rigidity polyolefin composite material, comprising the following components by weight: 60-80 parts of polypropylene resin, 15-30 parts of surface-etched glass fiber, 5-15 parts of sheet-like heat-resistant filler, 0-5 parts of spherical auxiliary filler, 2-6 parts of maleic anhydride-grafted polypropylene compatibilizer, 0.2-1 parts of antioxidant, and 0.1-0.5 parts of lubricant; The composite material has an alternating multilayer structure with a total of 2-128 layers and a thickness of 50-200 μm for each layer; The odd-numbered layers are glass fiber reinforced polypropylene layers, which are composed of polypropylene resin and surface-etched glass fibers. The even-numbered layers are heat-resistant rigid reinforcement layers, composed of polypropylene resin, sheet-like heat-resistant fillers, and spherical auxiliary fillers; The surface-etched glass fiber has a nanoscale porous structure, which forms a mechanically interlocking interface with the polypropylene matrix. The glass fiber has an orientation degree of ≥70% along the extrusion direction within the layer, and the orientation degree is determined by the sound velocity method.

[0010] Furthermore, the surface-etched glass fiber has an average diameter of 3-8 μm, an initial length of 3-6 mm, and a retention length of 0.2-0.8 mm in the composite material; the surface etching depth is 0.1-0.5 μm, and the average diameter of the etched holes is 0.05-0.2 μm.

[0011] Furthermore, the sheet-like heat-resistant filler is one or more of mica, talc, boron nitride, and kaolin, with an average sheet diameter of 1-10 μm and an average thickness of 0.05-0.5 μm; the spherical auxiliary filler is one or more of nano-calcium carbonate, spherical silica, and glass microspheres, with an average particle size of 0.1-2 μm.

[0012] Furthermore, the thickness ratio of the glass fiber reinforced polypropylene layer to the heat-resistant rigid reinforcement layer is (1-3):1.

[0013] Furthermore, the grafting rate of the maleic anhydride-grafted polypropylene is 0.8-2.5%, the melt flow rate is 5-20 g / 10 min, and the test conditions are 230℃ and 2.16 kg.

[0014] Furthermore, 30%-60% of the total amount of maleic anhydride-grafted polypropylene is used to coat the surface-etched glass fibers, and the remaining portion is used to prepare heat-resistant masterbatch.

[0015] Furthermore, the antioxidant is one or more of hindered phenolic antioxidant 1010, antioxidant 1076, and phosphite antioxidant 168; the lubricant is one or more of calcium stearate, zinc stearate, polyethylene wax, and ethylene bis-stearamide.

[0016] A method for preparing a high heat-resistant and high-rigidity polyolefin composite material includes the following steps: S1. Surface treatment of glass fiber: The glass fiber is placed in an etching solution for surface etching treatment, washed with deionized water until neutral, and then dried; the etched glass fiber is then immersed in a 2-5% (w / w) solution of maleic anhydride-grafted polypropylene toluene, stirred for 10-30 min, and dried to remove the solvent, resulting in glass fiber with surface etching and compatibilizer coating; the etching solution is a 5-15 wt% hydrofluoric acid solution or a 10-20 wt% sodium hydroxide solution. S2. Preparation of heat-resistant masterbatch: Weigh polypropylene resin, flake heat-resistant filler, spherical auxiliary filler, maleic anhydride-grafted polypropylene for preparing heat-resistant masterbatch, antioxidant, and lubricant according to the weight parts, add them to a high-speed mixer and mix for 3-10 minutes to obtain a premix; add the premix to a twin-screw extruder, use a low-shear screw element, and extrude and granulate at 180-220℃ to obtain heat-resistant masterbatch; S3. Alternating multilayer co-extrusion molding: Polypropylene resin is added to the main feed port of the first single-screw extruder, and surface-treated glass fiber is added to the first single-screw extruder through the side feed port. The glass fiber reinforced polypropylene melt is obtained by melt extrusion. Heat-resistant masterbatch is added to the second single-screw extruder and melt extruded to obtain a heat-resistant rigid reinforcing layer melt. The two melts enter the layer multiplier through the confluencer, and after being cut and superimposed, they form an alternating multilayer melt, which is then extruded from the die and cooled and shaped by the traction roller to obtain the high heat-resistant and high rigidity polyolefin composite material.

[0017] Furthermore, in step S1, when hydrofluoric acid solution is used for etching, the processing time is 5-30 min and the processing temperature is room temperature; when sodium hydroxide solution is used for etching, the processing time is 10-40 min and the processing temperature is 80-100℃; the coating amount of maleic anhydride grafted polypropylene is 2-5% of the glass fiber mass.

[0018] Furthermore, in step S3, the temperature range of the first single-screw extruder is 180-220℃, and the screw speed is 150-300rpm; the temperature range of the second single-screw extruder is 170-210℃, and the screw speed is 150-300rpm; the temperature of the manifold and layer multiplier is 210-230℃; the traction speed is 5-20m / min; and the stretching ratio of the melt in the layer multiplier is controlled to be (2-4):1, where the stretching ratio is the ratio of the cross-sectional area of ​​the melt at the inlet to the cross-sectional area at the outlet of the layer multiplier.

[0019] The beneficial effects of this invention are: This invention utilizes a combination of core technologies, including glass fiber surface etching modification, alternating multilayer directional reinforcement, precise compatibilizer distribution, low-shear side feeding for strength maintenance, and layer multiplication stretching orientation, to achieve synergistic optimization across multiple dimensions such as interface bonding, phase structure, processing technology, and component dispersion. Compared to existing technologies, it offers the following significant advantages: A nanoporous structure is constructed by etching the surface of glass fiber, and then coated with maleic anhydride-grafted polypropylene compatibilizer to form a dual interface bonding mechanism of physical-mechanical interlocking and chemical bonding. This completely solves the problems of weak interface bonding and easy delamination at high temperatures caused by traditional coupling agents, and significantly improves the interface stability and structural integrity of the material.

[0020] By employing side-feeding and low-shear screw elements, excessive breakage of glass fibers during melt processing is minimized, preserving effective reinforcement length. Combined with the gentle stretching effect of the layer multiplier, high orientation of glass fibers along the extrusion direction is achieved, significantly improving load transfer efficiency and fully leveraging the reinforcement advantages of glass fibers.

[0021] The alternating multilayer structure of odd-numbered glass fiber reinforcement and even-numbered sheet-like heat-resistant filler reinforcement achieves a complementary effect of longitudinal fiber load-bearing reinforcement and planar heat-resistant rigid support of the sheets. This breaks through the technical bottleneck of the difficulty in achieving both heat resistance and rigidity in a single reinforcement system, while also reducing material anisotropy and improving dimensional stability.

[0022] The spherical auxiliary filler and the sheet-like heat-resistant filler work together to optimize the internal stress distribution of the system, improve the interlayer bonding state, avoid the local loose defects caused by the high orientation structure, and make the internal structure of the composite material more uniform and the overall integrity stronger.

[0023] The compatibilizer is used in proportion for glass fiber coating and heat-resistant masterbatch preparation, resulting in more uniform component dispersion; the step-by-step melt blending and alternating multilayer co-extrusion processes are well matched, the melt flow is stable during continuous production, there are no problems such as filler agglomeration, product delamination and warping, the product batch consistency is high, and it is suitable for large-scale industrial production. Attached Figure Description

[0024] Figure 1 This is an overall flowchart of a method for preparing a high heat-resistant and high-rigidity polyolefin composite material proposed in this invention. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0026] In the description of this application, it should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. For ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0027] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and are not limited in number; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0028] It should be noted that in the description of this application, the directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this application. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0029] It should be noted that, in this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0030] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0031] All embodiments and comparative examples of this invention use the following general process conditions; parameters not specifically mentioned are performed accordingly: Polypropylene resin: homopolymer polypropylene, melt flow rate 10g / 10min (230℃, 2.16kg). Surface-etched glass fiber: average diameter 5μm, initial length 4mm; Flaky heat-resistant filler: mica, average flake diameter 5μm, average thickness 0.2μm; Spherical auxiliary filler: nano-calcium carbonate, average particle size 1μm; Maleic anhydride-grafted polypropylene: grafting rate 1.5%, melt flow rate 10g / 10min (230℃, 2.16kg). Antioxidant: Antioxidant 1010 and phosphite antioxidant 168 are compounded at a mass ratio of 1:1; Lubricant: Ethylene bis-stearamide; Twin-screw extruder: length-to-diameter ratio L / D=40:1, equipped with low-shear screw elements; Alternating multilayer co-extrusion equipment: including main / side feeding unit, manifold, layer multiplier, traction cooling and shaping unit; Characterization methods: fiber retention length (microscopic observation), orientation degree (sound velocity method), interlayer bonding state (manual bending and peeling observation; processing stability: no fluctuation for 30 minutes of continuous production is considered stable), processing stability (determination of continuous production status).

[0032] Example 1: like Figure 1 As shown in the figure, this embodiment provides a method for preparing a high heat-resistant and high-rigidity polyolefin composite material, the steps of which are as follows: S1. Glass fiber surface treatment: The glass fiber is placed in a 10wt% sodium hydroxide solution and treated at 90℃ for 25 min. After washing with deionized water until neutral, it is dried. Then, the etched glass fiber is immersed in a 3% (w / w) maleic anhydride-grafted polypropylene toluene solution and stirred for 20 min. After drying to remove the solvent, the surface-etched glass fiber coated with a compatibilizer is obtained, with a coating amount of 3.5% of the glass fiber mass. S2. Preparation of heat-resistant masterbatch: Weigh 40 parts by weight of polypropylene resin, 10 parts by weight of mica, 3 parts by weight of nano-calcium carbonate, 1.2 parts by weight of maleic anhydride-grafted polypropylene, 0.3 parts by weight of antioxidant, and 0.2 parts by weight of lubricant. Add them to a high-speed mixer and mix for 5 minutes to obtain a premix. Add the premix to a twin-screw extruder and use a low-shear screw element to extrude and granulate at 190-210℃ to obtain heat-resistant masterbatch. S3. Alternating multilayer co-extrusion molding: By weight, the total raw material composition is: 70 parts polypropylene resin, 20 parts surface-etched glass fiber, 10 parts sheet-like heat-resistant filler, 3 parts spherical auxiliary filler, 4 parts maleic anhydride-grafted polypropylene, 0.5 parts antioxidant, and 0.3 parts lubricant; of which 40% of the total amount of maleic anhydride-grafted polypropylene is used to coat the glass fiber, and 60% is used to prepare heat-resistant masterbatch; Polypropylene resin is added to the main feed port of the first single-screw extruder, and surface-treated glass fiber is added to the first single-screw extruder through the side feed port. The mixture is melt-extruded to obtain an odd number of layers: glass fiber reinforced polypropylene layers. Heat-resistant masterbatch is added to the second single-screw extruder, and the mixture is melt-extruded to obtain an even number of layers: heat-resistant rigid reinforcement layers. The two melt streams enter the layer multiplier through a manifold, and are cut and stacked to form a 64-layer alternating multilayer structure with a single layer thickness of 120μm and a glass fiber reinforced layer to heat-resistant rigid reinforcement layer thickness ratio of 2:1. Process parameters: The temperature of the first single-screw extruder is 190-210℃ and the speed is 200 rpm; the temperature of the second single-screw extruder is 180-200℃ and the speed is 200 rpm; the temperature of the manifold and layer multiplier is 220℃; the traction speed is 10 m / min; the draw ratio is 3:1; the extrudate is cooled and shaped by the traction roller to obtain the high heat-resistant and high rigidity polyolefin composite material.

[0033] Example 2: The only difference between this embodiment and Embodiment 1 is that: Total raw material composition: 65 parts polypropylene resin, 25 parts surface-etched glass fiber, 8 parts sheet-like heat-resistant filler, 2 parts spherical auxiliary filler, 5 parts maleic anhydride-grafted polypropylene, 0.6 parts antioxidant, and 0.3 parts lubricant; Glass fiber etching was performed using an 8 wt% hydrofluoric acid solution at room temperature for 15 minutes. The alternating multilayer structure has 128 layers, with a single layer thickness of 80μm; The stretch ratio is 3.5:1.

[0034] Example 3: The only difference between this embodiment and Embodiment 1 is that: The sheet-like heat-resistant filler was replaced with talc, and the spherical auxiliary filler was replaced with spherical silica. 50% of the total amount of maleic anhydride-grafted polypropylene is used to coat glass fibers, and 50% is used to prepare heat-resistant masterbatch. The alternating multilayer structure has 32 layers, with a single layer thickness of 150μm; The thickness ratio of the fiberglass reinforcement layer to the heat-resistant rigid reinforcement layer is 1.5:1.

[0035] Example 4: The only difference between this embodiment and Embodiment 1 is that: No spherical auxiliary filler is added; Glass fiber etching was performed using a 15wt% sodium hydroxide solution at 95°C for 20 minutes. The first and second single-screw extruders both operate at 250 rpm. The alternating multilayer structure consists of 16 layers, with each layer having a thickness of 180 μm.

[0036] Example 5: The only difference between this embodiment and Embodiment 1 is that: Total raw material composition: 75 parts polypropylene resin, 15 parts surface-etched glass fiber, 8 parts sheet-like heat-resistant filler, 2 parts spherical auxiliary filler, 3 parts maleic anhydride-grafted polypropylene, 0.4 parts antioxidant, and 0.2 parts lubricant; Traction speed 15m / min; The stretch ratio is 2.5:1; The alternating multilayer structure consists of 8 layers, with each layer having a thickness of 100 μm.

[0037] Comparative Example 1 (without glass fiber surface etching): The only difference between this comparative example and Example 1 is that the glass fiber was not etched, but only surface treated with a conventional silane coupling agent.

[0038] Comparative Example 2 (no alternating multilayer structure, ordinary blend): The only difference between this comparative example and Example 1 is that all components are directly mixed and then co-extruded using a conventional single-screw extruder, without the use of alternating multi-layer co-extrusion and layer multiplier structures.

[0039] Comparative Example 3 (without spherical auxiliary packing): The only difference between this comparative example and Example 1 is that no spherical auxiliary filler is added; all other formulations and preparation processes remain unchanged.

[0040] Comparative Example 4 (without low-shear screw + side feed): The only difference between this comparative example and Example 1 is that the glass fiber is added through the main feed port, and the extruder uses a conventional high-shear screw element.

[0041] The characterization results of Examples 1-5 and Comparative Examples 1-4 are compared in the table below:

[0042] Compared to existing technologies: This invention combines core technologies such as surface etching mechanical interlocking, alternating multilayer synergistic reinforcement, precise compatibilizer distribution, low-shear side feeding for strength preservation, and layer multiplication for high orientation shaping. These innovative aspects are coupled to produce a synergistic effect, fundamentally optimizing the interfacial bonding, structural uniformity, and processing stability of polyolefin composites. It possesses outstanding non-obviousness and inventiveness. Synergistic effect of surface etching and compatibilizer coating: The nanopores formed by etching provide physical anchoring, which, together with the compatibilizer chemical bonding, doubly strengthens the interface bonding and solves the problems of weak interface bonding and easy delamination of conventional coupling agents. Alternating multi-layer structure and filler orientation work synergistically: odd-numbered layers of highly oriented glass fiber provide a load-bearing skeleton, while even-numbered layers of planar sheet filler provide heat-resistant rigid support, complementing each other to improve structural stability; Synergistic effect of spherical auxiliary filler and multilayer structure: It can adjust the stress distribution of the system, avoid interlayer porosity caused by high orientation, and improve the structural uniformity. Synergistic effect of low-shear screw and side feeding: maximizes the preservation of effective glass fiber length and avoids the reduction of reinforcement effect caused by fiber breakage.

[0043] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A high heat-resistant and high-rigidity polyolefin composite material, characterized in that, By weight, it includes the following components: 60-80 parts polypropylene resin, 15-30 parts surface-etched glass fiber, 5-15 parts sheet-like heat-resistant filler, 0-5 parts spherical auxiliary filler, 2-6 parts maleic anhydride-grafted polypropylene compatibilizer, 0.2-1 parts antioxidant, and 0.1-0.5 parts lubricant. The composite material has an alternating multilayer structure with a total of 2-128 layers and a thickness of 50-200 μm for each layer; The odd-numbered layers are glass fiber reinforced polypropylene layers, which are composed of polypropylene resin and surface-etched glass fibers. The even-numbered layers are heat-resistant rigid reinforcement layers, composed of polypropylene resin, sheet-like heat-resistant fillers, and spherical auxiliary fillers; The surface-etched glass fiber has a nanoscale porous structure, which forms a mechanically interlocking interface with the polypropylene matrix. The glass fiber has an orientation degree of ≥70% along the extrusion direction within the layer, and the orientation degree is determined by the sound velocity method.

2. The high heat-resistant and high-rigidity polyolefin composite material according to claim 1, characterized in that, The surface-etched glass fibers have an average diameter of 3-8 μm, an initial length of 3-6 mm, and a retained length of 0.2-0.8 mm in the composite material; the surface etching depth is 0.1-0.5 μm, and the average diameter of the etched holes is 0.05-0.2 μm.

3. The high heat-resistant and high-rigidity polyolefin composite material according to claim 1, characterized in that, The sheet-like heat-resistant filler is one or more of mica, talc, boron nitride, and kaolin, with an average sheet diameter of 1-10 μm and an average thickness of 0.05-0.5 μm; the spherical auxiliary filler is one or more of nano-calcium carbonate, spherical silica, and glass microspheres, with an average particle size of 0.1-2 μm.

4. The high heat-resistant and high-rigidity polyolefin composite material according to claim 1, characterized in that, The thickness ratio of the glass fiber reinforced polypropylene layer to the heat-resistant rigid reinforcement layer is (1-3):

1.

5. The high heat-resistant and high-rigidity polyolefin composite material according to claim 1, characterized in that, The maleic anhydride-grafted polypropylene has a grafting rate of 0.8-2.5%, a melt flow rate of 5-20 g / 10 min, and is tested at 230℃ and 2.16 kg.

6. The high heat-resistant and high-rigidity polyolefin composite material according to claim 5, characterized in that, 30%-60% of the total amount of maleic anhydride-grafted polypropylene is used to coat the surface-etched glass fibers, and the remainder is used to prepare heat-resistant masterbatch.

7. The high heat-resistant and high-rigidity polyolefin composite material according to claim 1, characterized in that, The antioxidant is one or more of hindered phenolic antioxidant 1010, antioxidant 1076, and phosphite antioxidant 168; the lubricant is one or more of calcium stearate, zinc stearate, polyethylene wax, and ethylene bis-stearamide.

8. A method for preparing a high heat-resistant and high-rigidity polyolefin composite material according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Surface treatment of glass fiber: The glass fiber is placed in an etching solution for surface etching treatment, washed with deionized water until neutral, and then dried; the etched glass fiber is then immersed in a 2-5% (w / w) solution of maleic anhydride-grafted polypropylene toluene, stirred for 10-30 min, and dried to remove the solvent, resulting in glass fiber with surface etching and compatibilizer coating; the etching solution is a 5-15 wt% hydrofluoric acid solution or a 10-20 wt% sodium hydroxide solution. S2. Preparation of heat-resistant masterbatch: Weigh polypropylene resin, flake heat-resistant filler, spherical auxiliary filler, maleic anhydride-grafted polypropylene for preparing heat-resistant masterbatch, antioxidant, and lubricant according to the weight parts, add them to a high-speed mixer and mix for 3-10 minutes to obtain a premix; add the premix to a twin-screw extruder, use a low-shear screw element, and extrude and granulate at 180-220℃ to obtain heat-resistant masterbatch; S3. Alternating multilayer co-extrusion molding: Polypropylene resin is added to the main feed port of the first single-screw extruder, and surface-treated glass fiber is added to the first single-screw extruder through the side feed port. The glass fiber reinforced polypropylene melt is obtained by melt extrusion. Heat-resistant masterbatch is added to the second single-screw extruder and melt extruded to obtain a heat-resistant rigid reinforcing layer melt. The two melts enter the layer multiplier through the confluencer, and after being cut and superimposed, they form an alternating multilayer melt, which is then extruded from the die and cooled and shaped by the traction roller to obtain the high heat-resistant and high rigidity polyolefin composite material.

9. The preparation method according to claim 8, characterized in that, In step S1, when hydrofluoric acid solution is used for etching, the processing time is 5-30 min and the processing temperature is room temperature; when sodium hydroxide solution is used for etching, the processing time is 10-40 min and the processing temperature is 80-100℃; the coating amount of maleic anhydride grafted polypropylene is 2-5% of the glass fiber mass.

10. The preparation method according to claim 8, characterized in that, In step S3, the temperature range of the first single-screw extruder is 180-220℃, and the screw speed is 150-300 rpm; the temperature range of the second single-screw extruder is 170-210℃, and the screw speed is 150-300 rpm; the temperature of the manifold and layer multiplier is 210-230℃; the traction speed is 5-20 m / min; and the stretching ratio of the melt in the layer multiplier is controlled to be (2-4):1, where the stretching ratio is the ratio of the cross-sectional area of ​​the melt at the inlet to the cross-sectional area at the outlet of the layer multiplier.

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