High and low temperature resistant polypropylene composite material as well as preparation method and application thereof

Abstract

The invention discloses a high and low temperature resistant polypropylene composite material as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. The composite material comprises the following components in parts by weight: 40-70 parts of polypropylene resin; 5-15 parts of a welding improver; 5 to 45 parts of glass fiber; 0.5 to 1.5 parts of an antioxidant; 3-8 parts of a compatilizer; 0.1-1 part of a release agent; 0.2 to 0.5 part of a heat-resistant agent; the thermal deformation temperature of the composite material is greater than or equal to 122 DEG C, the low-temperature simply supported beam notch impact strength is greater than or equal to 11KJ / m, and the composite material has high strength, high rigidity, excellent welding performance, high transparency and hydrolysis resistance.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a high and low temperature resistant polypropylene composite material, its preparation method and application. Background Technology

[0002] Polypropylene (PP), as an important polymer material, has been widely used and promoted in many fields due to its excellent processing and molding properties and relatively low production cost. However, polypropylene itself has inherent defects; its mechanical properties and heat resistance are relatively weak, making it difficult to meet the requirements of some harsh environments. This, to some extent, limits the further expansion of its application range.

[0003] To improve the mechanical properties and heat resistance of polypropylene, the industry typically modifies it by adding reinforcing fillers. Among these methods, glass fiber (GF) reinforcement is one of the most common and effective. Introducing glass fibers can significantly improve the tensile strength, flexural modulus, impact strength, and heat distortion temperature of polypropylene composites, enabling them to meet the requirements of a wider range of structural components. However, because glass fibers are inorganic rigid fillers, they cannot form a strong weld interface in the molten polypropylene matrix through mutual diffusion and entanglement like polymer chains. Instead, the presence of glass fibers at the weld interface hinders the fusion of resin molecules and creates defects due to poor interfacial compatibility between inorganic and organic materials, resulting in a weld joint strength far lower than the strength of the material itself.

[0004] To address the poor weldability of GFP (glass fiber reinforced polymer), existing technologies typically attempt to solve the problem from two aspects: First, by increasing the melt adhesion of the matrix resin, for example, by adding large amounts of low-melting-point, high-toughness polymers such as polyolefin elastomers (POE) and polyethylene (PE) as "welding aids," thereby partially compensating for the losses caused by the weakening of the glass fiber interface by improving the weld strength between the resin bodies. However, this method often comes at the cost of sacrificing the material's valuable rigidity, strength, and heat resistance, which contradicts the original intention of using glass fiber reinforcement. Second, by using grafted polypropylene as a compatibilizer. However, the grafting rate of this material is extremely low, and it is essentially more compatible with polypropylene, still exhibiting repulsion towards inorganic mineral fillers such as glass fiber and talc. Therefore, it cannot truly achieve a balance between glass fiber and resin compatibility, and the effect on improving the overall weld strength is not ideal.

[0005] Furthermore, some applications, such as polypropylene water tanks, place demands on its transparency and hydrolysis resistance. Polypropylene itself is a semi-crystalline material, and the presence of crystalline regions significantly reduces its transparency. Adding glass fiber further complicates matters due to the mismatch in refractive indices between the glass fiber and the polypropylene resin, leading to severe light refraction and reflection at their interface. This results in a complex optical path and further reduces the material's transparency. Simultaneously, water tank materials are exposed to water in high and low temperature environments for extended periods. Under these alternating hot and cold conditions, the interface between the glass fiber and resin is already fragile and easily damaged by stress. In such situations, water molecules and solvents can easily penetrate the resin material, further reducing its strength and transparency.

[0006] Therefore, developing a composite material that can maintain the excellent high strength, high rigidity and heat resistance of glass fiber reinforced polypropylene, while also possessing excellent weldability and being able to withstand high and low temperature cycles and long-term effects in aquatic environments has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] To address the technical deficiencies of existing polypropylene composite materials in terms of interfacial compatibility, weldability, high and low temperature resistance, transparency, and hydrolysis resistance, this invention provides a high and low temperature resistant polypropylene composite material, its preparation method, and its application. By optimizing components such as polypropylene resin, glass fiber, welding modifier, antioxidant, and compatibilizer, and combining them with a specific preparation process, the overall performance of the material is synergistically improved.

[0008] This invention provides a high and low temperature resistant polypropylene composite material, comprising the following components by weight: 40-70 parts polypropylene resin; 5-15 parts welding modifier; 5-45 parts glass fiber; 0.5-1.5 parts antioxidant; 3-8 parts compatibilizer; 0.1-1 part release agent; and 0.2-0.5 parts heat resistant agent. The high and low temperature resistant polypropylene composite material has a heat distortion temperature ≥122℃ and a low temperature simply supported beam notched impact strength ≥11KJ / m².

[0009] The combination of the above components is not a simple superposition of performance, but rather a multi-dimensional synergistic effect achieved based on the molecular structure characteristics and mechanism of action of each component. From a macroscopic performance perspective, this formulation, by adjusting the proportions of the matrix resin, reinforcing phase, and functional additives, forms a three-dimensional performance system with enhanced rigidity, optimized interface, and functional protection. From a microscopic mechanism perspective, the intermolecular interactions of each component form a stable structural network. Polypropylene resin, as the continuous phase matrix, provides the material with basic processing fluidity and mechanical support, and its flexible molecular chain characteristics can alleviate stress concentration within the material. Glass fiber, as the dispersed phase reinforcement, significantly improves the rigidity and strength of the material through its "skeleton support" effect, and its high aspect ratio structure can effectively prevent crack propagation. Welding modifier, as an interface regulator, forms chemical bonds with glass fiber and resin through the polar groups of its molecular chains, improving interfacial compatibility during the welding process. Antioxidant and heat resistant agent form a synergistic protection system, delaying material aging from three dimensions: free radical capture, hydrogen peroxide decomposition, and surface protection. Compatibilizer, as a "molecular bridge," reduces the interfacial tension between components and promotes uniform dispersion. Release agent, by forming a lubricating layer on the material surface, ensures smooth processing. The weight proportions of each component were optimized through numerous experiments, and the precise ratio ultimately achieved a synergistic balance of multiple core advantages, including high strength, oxidation resistance, resistance to high and low temperatures, and good weldability.

[0010] Furthermore, the polypropylene resin is one or more of homopolymer polypropylene, copolymer polypropylene, and syndiotactic polypropylene.

[0011] The differences in molecular structure among different types of polypropylene are the main reason for their performance differences. This invention achieves precise control over material properties by selecting different types of polypropylene, either alone or in combination. Homopolymer polypropylene is polymerized from a single propylene monomer, exhibiting high stereoregularity, tight molecular chain arrangement, and high crystallinity, thus possessing excellent rigidity, tensile strength, and heat resistance. Copolymer polypropylene is a random copolymer of propylene and ethylene. The introduction of ethylene monomers disrupts the stereoregularity of the polypropylene molecular chain, reducing crystallinity. At the same time, the flexibility of the ethylene segments enhances the mobility of the molecular chain, giving the material good low-temperature impact toughness and processing fluidity. Syndiotactic polypropylene exhibits syndiotactic-isoregularity, with methyl groups alternating on both sides of the molecular chain. It crystallizes more slowly, resulting in smaller and more uniform crystal sizes and lower crystallinity compared to homopolymer polypropylene. This ensures the material's mechanical properties while reducing light scattering and improving transparency through refined crystal regions. In the random transparent polypropylene molecular structure, ethylene monomers are randomly embedded in the polypropylene molecular chain, which disrupts the stereoregularity of the polypropylene molecular chain and significantly reduces the crystallinity of the material. Although the transparency is high, the mechanical strength, heat resistance and hydrolysis resistance of the material are insufficient.

[0012] When syndiotactic polypropylene is used in combination with homopolymer and copolymer polypropylene, the molecular chains of the three polypropylenes can form mutual entanglement. The rigid segments of homopolymer polypropylene, the flexible segments of copolymer polypropylene, and the regular segments of syndiotactic polypropylene work together to avoid the performance shortcomings caused by a single segment structure, and finally achieve a synergistic balance of material transparency, rigidity, toughness and processing performance.

[0013] Preferably, the polypropylene resin is selected from two or three types of polypropylene: homopolymer polypropylene, copolymer polypropylene, and syndiotactic polypropylene, or a combination thereof. The weight ratio of homopolymer polypropylene, copolymer polypropylene, and syndiotactic polypropylene in the polypropylene resin can be (20-65):(0-35):(0-25), with the sum of the three being 40-70 parts by weight.

[0014] Furthermore, the glass fiber is a hydrolysis-resistant chopped glass fiber with a diameter of 10-14 μm and a length of 3-6 mm.

[0015] The surface of hydrolysis-resistant glass fiber is treated with a specialized impregnation modifier, such as an epoxy-based impregnation modifier. The epoxy groups in the modifier molecule can undergo a ring-opening reaction with the hydroxyl groups on the glass fiber surface, forming a stable chemical bond and constructing an organic-inorganic composite protective layer on the glass fiber surface. Simultaneously, the hydrophobic groups (such as alkyl chains) in the modifier molecule can form a hydrophobic film on the glass fiber surface, effectively blocking water molecules from contacting the glass fiber surface and preventing hydrolysis. This hydrolysis-resistant modification mechanism blocks the erosion of the glass fiber-resin interface by water molecules at the source, significantly improving the material's service life in humid and hot environments. Regarding fiber size parameters, the design with a diameter of 10-14 μm and a length of 3-6 mm is based on a balance between reinforcement effect and processing performance. Too small a fiber diameter leads to insufficient fiber strength, making it prone to breakage during processing and unable to provide reinforcement; too large a diameter increases the interfacial tension between the fiber and resin, resulting in uneven dispersion and stress concentration. The 3-6mm fiber length design ensures a suitable aspect ratio. According to the mechanical theory of fiber-reinforced composites, a suitable aspect ratio allows the fiber to transfer stress through the interface under stress, fully utilizing the fiber's high strength advantage. If the fiber length is too short, the aspect ratio is insufficient, resulting in low stress transfer efficiency and limited reinforcement effect. If the fiber length is too long, it will entangle with each other during processing, forming agglomerates and affecting the material's uniformity and processing flowability. Furthermore, the end faces of the chopped fibers are polished to reduce the cutting effect of sharp ends on the resin molecular chains, further improving the material's toughness. Moreover, the interfacial interaction between the hydrolysis-resistant glass fiber and polypropylene resin is not a simple mechanical embedding, but a stable bond achieved through a dual action of "chemical bonding and physical entanglement." The epoxy-modified layer on the glass fiber surface can chemically react with the maleic anhydride groups in the compatibilizer to form covalent bonds, while the organic segments in the modified layer can physically entangle with the polypropylene molecular chains. This dual action significantly reduces interfacial tension and improves interfacial bonding strength. When the material is subjected to external force, the stress can be quickly transferred to the glass fiber through the interface, and the glass fiber bears the main stress, avoiding material fracture caused by stress concentration, thereby significantly improving the tensile strength, flexural strength and impact strength of the composite material.

[0016] Furthermore, the antioxidant is one or more of hindered phenolic antioxidants and phosphite antioxidants.

[0017] The thermo-oxidative aging of polypropylene materials is essentially a free radical chain reaction that occurs in the molecular chains under high temperature and oxygen conditions. The specific process includes: an initiation stage, where oxygen reacts with the polypropylene molecular chains to generate hydroperoxide (ROOH), and the hydroperoxide decomposes to produce free radicals (R...). RO HO In the chain reaction (chain reaction), free radicals react with molecular chains to generate new free radicals, leading to chain breakage or cross-linking. In the termination stage, free radicals combine to form stable compounds, ending the reaction. The mechanism of action of antioxidants lies in blocking the key steps of this chain reaction, thus slowing down the aging process.

[0018] Hindered phenolic antioxidants contain active hydrogen atoms in their molecular structure, allowing them to react with free radicals, converting them into stable compounds and forming stable phenoxy radicals themselves, thus interrupting the chain reaction of free radicals. The steric hindrance of hindered phenolic antioxidants results in highly stable phenoxy radicals that do not initiate new chain reactions, thus providing long-lasting antioxidant effects. Phosphite antioxidants decompose hydroperoxides, converting them into inactive alcohol compounds, preventing the decomposition of hydroperoxides from generating new free radicals. They also synergistically interact with primary antioxidants, regenerating the active hydrogen atoms of the primary antioxidants and enhancing their antioxidant efficiency.

[0019] Furthermore, the compatibilizer is maleic anhydride-grafted polypropylene with a grafting rate of 2-5%.

[0020] The role of compatibilizers in composite materials is to improve the interfacial compatibility of components, reduce interfacial tension, and promote uniform dispersion. Maleic anhydride-grafted polypropylene (MPP) has two key molecular structures: the polypropylene backbone and the maleic anhydride grafting groups. The polypropylene backbone has the same chemical structure as the matrix polypropylene resin, exhibiting excellent compatibility and allowing for tight entanglement with the matrix molecular chains. The maleic anhydride grafting groups are highly polar and can chemically react with the hydroxyl groups on the glass fiber surface and the polar groups in welding modifiers to form stable chemical bonds. This creates a "molecular bridge" between the glass fiber and the polypropylene, significantly improving interfacial compatibility.

[0021] This invention limits the grafting rate to 2-5%, a range optimized through extensive testing. When the grafting rate is too low, the number of maleic anhydride groups is insufficient, preventing them from fully reacting with the hydroxyl groups on the glass fiber surface and the polar groups of the welding modifier, resulting in limited improvement in interfacial bonding. A suitable grafting rate ensures that the compatibilizer possesses sufficient active groups to improve interfacial compatibility while maintaining good dispersibility, avoiding performance defects caused by self-agglomeration.

[0022] Compared with traditional compatibilizers with low grafting rates (<1%), the maleic anhydride-grafted polypropylene used in this invention significantly improves interfacial bonding strength. Traditional compatibilizers, due to their low grafting rates, can only form chemical bonds at some interfaces, with most interfaces still relying on mechanical interlocking, resulting in numerous interfacial defects. In contrast, the compatibilizer of this invention can form a continuous chemical bond layer at the glass fiber and resin interface, effectively eliminating interfacial defects. When the material is subjected to external forces, stress can be rapidly transferred through the interface, avoiding interfacial separation caused by stress concentration, thereby significantly improving the mechanical properties and welding reliability of the composite material.

[0023] Furthermore, the welding modifier is selected from one or more of the following: ethylene-propylene random copolymer, ethylene-methacrylic acid metal salt polymer, ethylene-methacrylic acid copolymer, and ethylene-vinyl acetate copolymer.

[0024] A significant problem with the low weld strength of glass fiber reinforced polypropylene lies in the poor interfacial compatibility between glass fiber and resin. Welding modifiers aim to improve this compatibility with both glass fiber and resin, thereby enhancing the melt bonding force during welding. The welding modifier selected in this invention contains polar groups (such as carboxyl groups, metal ionic bonds, and ester groups) and non-polar segments (such as ethylene and propylene segments). The non-polar segments exhibit good compatibility with the polypropylene resin molecular chain, allowing for tight entanglement. The polar groups can chemically react with the hydroxyl groups on the glass fiber surface and the maleic anhydride groups in the compatibilizer, forming stable chemical bonds and significantly improving weld strength.

[0025] Ethylene-methacrylate metal salt polymers are a class of high-performance welding modifiers. The metal ionic bonds in their molecular structure have a unique mechanism of action: on the one hand, the metal ionic bonds can form strong ion-dipole interactions with the hydroxyl groups on the glass fiber surface, significantly improving the compatibility between the welding modifier and the glass fiber; on the other hand, the metal ions can form a three-dimensional network cross-linked structure in the molten state. This cross-linked structure can serve as the "skeleton" of the weld melt, significantly improving the melt strength and weld firmness, and forming a stable weld bond layer after cooling. Compared with traditional POE and PE welding modifiers, ethylene-methacrylate metal salt polymers have superior heat resistance and do not reduce the heat distortion temperature or rigidity of the material upon addition.

[0026] The welding modifier for ethylene-vinyl acetate copolymer has hydrogen bonding between the ester groups (-COO-) in its molecular chain and the hydroxyl groups on the glass fiber surface, as well as entanglement with the resin molecular chain. During the welding process, it can effectively fill the tiny gaps at the welding interface, improve the density of the welding interface, and avoid the decrease in welding strength caused by gaps.

[0027] Ethylene-propylene random copolymer (EPC) and ethylene-methacrylic acid copolymer (EMA) improve welding performance through the flexible characteristics of molecular chains and the synergistic effect of polar groups: the propylene segments of EPC have excellent compatibility with the matrix polypropylene, while the ethylene segments enhance melt fluidity, making it easier for the melt to wet the glass fiber surface during welding; the methacrylic acid groups of EMA can undergo esterification with the hydroxyl groups on the glass fiber surface to form chemical bonds, and at the same time, the flexibility of its molecular chains can alleviate internal stress during welding, avoiding cracking of the weld joint due to stress concentration.

[0028] By selecting the aforementioned welding modifier, this invention significantly improves welding strength compared to traditional techniques, while maintaining the high rigidity and heat resistance of the material, fully meeting the structural integrity requirements of water tank welding assembly.

[0029] More preferably, the weight ratio of the welding modifier to the glass fiber is 1:1 to 1:3. At this ratio, the amount of welding modifier is sufficient to ensure that its active functional groups (such as carboxylic acid groups and metal ions) can fully wet and effectively interact with the glass fiber surface during melt processing, minimizing the stress concentration effect of the glass fiber at the welding interface and transforming the weakest point in the weld joint into a reinforcing point. When the ratio is too low, the resulting interface "anchor points" are too sparse, limiting the improvement in weld strength. If the ratio is too high, excessive welding modifier will over-dilute the resin matrix, leading to a decrease in the flexural modulus and heat distortion temperature of the composite material.

[0030] Furthermore, the heat-resistant agent is selected from thioether antioxidants and thioester antioxidants.

[0031] Heat resistant agents and antioxidants work synergistically, providing unique high-temperature protection. Thioether antioxidants such as DLTP and DSTP decompose at high temperatures to produce thiols. Thiols have strong reducing properties, reacting with free radicals and decomposing hydroperoxides, thus forming a synergistic effect with the main antioxidant and enhancing high-temperature antioxidant performance. Thioester antioxidants such as pentaerythritol tetra(3-lauryl thiopropionate) combine the functions of decomposing hydroperoxides and lubrication. During high-temperature processing, they not only provide antioxidant protection but also improve melt flowability and reduce thermal degradation during processing.

[0032] Furthermore, the main components of the release agent are oleamide, erucamide, stearate, or silicone composition.

[0033] The present invention also provides a method for preparing the above-mentioned high and low temperature resistant polypropylene composite material, comprising the following steps:

[0034] S1. Mix polypropylene resin, welding modifier, antioxidant, compatibilizer, release agent and heat resistant agent to obtain a premix; S2. The premixed material is added through the main feed port of a twin-screw extruder, and the glass fiber is added through the side feed port, so that the premixed material and glass fiber are mixed and extruded in the twin-screw extruder to obtain a composite material; S3. The composite material is cooled, drawn, and pelletized in a water tank to obtain a high and low temperature resistant polypropylene composite material.

[0035] Furthermore, in step 1, the mixing speed of the high-speed mixer is 1000-1500 r / min, and the mixing time is 5-10 min.

[0036] High-speed stirring ensures uniform dispersion of various additives in polypropylene resin. If the stirring speed is too low or the stirring time is too short, the material experiences insufficient shear force, causing additives to easily agglomerate and preventing uniform dispersion. If the stirring speed is too high, the material temperature will rise rapidly due to frictional heat generation, potentially causing premature resin melting and affecting subsequent processing performance. Excessive stirring time not only increases energy consumption but may also lead to additive volatilization or decomposition, reducing their effectiveness.

[0037] Furthermore, in step 2, the twin-screw extruder is divided into 10-14 temperature zones, each with a temperature range of 160-230℃. Specifically, the first temperature zone has a temperature of 160-180℃, the second to fifth temperature zones have a temperature of 180-210℃, the sixth to tenth temperature zones have a temperature of 200-230℃, and the eleventh to fourteenth temperature zones have a temperature of 190-220℃.

[0038] The temperature zone design of a twin-screw extruder directly affects the melt quality and processing stability of the material. This invention employs a lower temperature in the first temperature zone to avoid premature melting of the premix, which could lead to feeding difficulties. The second to fifth temperature zones gradually increase in temperature, allowing the material to melt slowly and preventing resin degradation due to localized overheating. The sixth to tenth temperature zones are high-temperature zones, ensuring complete melting of the material and providing sufficient energy for the chemical reactions of each component. The eleventh to fourteenth temperature zones gradually decrease in temperature, preventing excessively rapid crystallization during extrusion and ensuring dimensional stability of the finished product. Compared to traditional single-temperature-zone or temperature-zone designs with excessively large temperature differences, the gradient temperature zone design of this invention achieves stable melting and full reaction of the material, reducing processing defects and improving the uniformity of material properties.

[0039] Furthermore, in step 2, the main rotation speed of the twin-screw extruder is 300-600 r / min, and the glass fiber feeding speed at the side feed port is matched with the main feeding speed to ensure that the glass fiber is uniformly dispersed in the melt and reduce fiber breakage.

[0040] Glass fiber is added via a side-feeding method, which avoids the strong shearing effect experienced when glass fiber and premix are added together at the main feed port, thus reducing glass fiber breakage. The side feed port is usually located in the middle to rear section of the barrel, where the premix has completely melted and the melt has good fluidity. After the glass fiber is added, it can be evenly dispersed in the melt. At the same time, the meshing action of the twin screws can evenly shear and disperse the glass fiber, preventing agglomeration.

[0041] This invention also protects the application of the above-mentioned high and low temperature resistant polypropylene composite material, specifically its use in water tanks.

[0042] The beneficial effects of this invention are as follows: This invention selects specific polypropylene resin, compatibilizer with a specific grafting rate, specific welding modifier, and limits the ratio of welding modifier to glass fiber. The components work together to significantly overcome many performance defects of traditional polypropylene composite materials, enabling the material to simultaneously possess high strength, oxidation resistance, high and low temperature resistance, good welding performance, excellent transparency, and hydrolysis resistance.

[0043] The preparation method of this invention has a reasonable process design. High-speed stirring and premixing ensures uniform dispersion of additives. The gradient temperature zone design and speed optimization of the twin-screw extruder realize stable melting and full reaction of materials. The side feeding method reduces the breakage loss of glass fibers. The preparation process is stable and controllable, and is suitable for large-scale industrial production. Detailed Implementation

[0044] The embodiments described in this invention are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0045] Example 1 This embodiment provides a high and low temperature resistant polypropylene composite material, which, by weight, comprises the following components: Homopolymer polypropylene 63.6 parts; 20 parts of hydrolysis-resistant chopped glass fibers (12μm in diameter, 4mm in length); 10 parts of ethylene-methacrylate metal salt polymer; 5 parts of maleic anhydride-grafted polypropylene (grafting rate 4%); Antioxidant 10100.5 parts; 0.5 parts of pentaerythritol tetra(3-lauryl thiopropionate); 0.4 parts of oleamide.

[0046] Preparation method: Step 1: Premix preparation: Add the polypropylene resin, welding modifier, compatibilizer, antioxidant, heat resistant agent and release agent from the above components into a high-speed mixer and stir at 1200 r / min for 8 min to obtain a uniform premix. Step 2: Compounding and Extrusion: The premix is ​​added through the main feed port of the twin-screw extruder, and the glass fiber is added through the side feed port (located in the eighth section of the barrel). The twin-screw extruder is divided into 14 temperature zones, and the temperature of each zone is set in a gradient: Zone 1 170℃, Zones 2 to 5 190℃, Zones 6 to 10 210℃, Zones 11 to 14 200℃, and the main machine speed is 450 r / min, so that the premix and glass fiber are fully compounded and extruded to obtain the composite material. Step 3: Post-processing: The composite material is cooled in a water tank, pulled by a traction machine, and pelletized by a pelletizer to obtain a high and low temperature resistant polypropylene composite material.

[0047] Example 2 This embodiment provides a high and low temperature resistant polypropylene composite material, which, by weight, comprises the following components: 58.6 parts of homopolymer polypropylene; 20 parts of hydrolysis-resistant chopped glass fibers (11 μm in diameter, 3.5 mm in length); 15 parts of ethylene methacrylate metal salt polymer; 5 parts of maleic anhydride-grafted polypropylene (grafting rate 4%); Antioxidant 10100.5 parts; 0.5 parts of pentaerythritol tetra(3-lauryl thiopropionate); 0.4 parts of oleamide.

[0048] The preparation method is as described in Example 1.

[0049] Example 3 This embodiment provides a high and low temperature resistant polypropylene composite material, which, by weight, comprises the following components: 30 parts homopolymer polypropylene; 10 parts of copolymerized polypropylene; 34 parts of hydrolysis-resistant chopped glass fibers (13μm in diameter, 5mm in length); 15 parts of ethylene methacrylate metal salt polymer; 8 parts of maleic anhydride-grafted polypropylene (grafting rate 4%); Antioxidant 1010 1.5 parts; 0.5 parts of pentaerythritol tetra(3-lauryl thiopropionate); One part of oleamide.

[0050] The preparation method is as described in Example 1.

[0051] Example 4 This embodiment provides a high and low temperature resistant polypropylene composite material, which, by weight, comprises the following components: 40 parts homopolymer polypropylene; 20 parts of copolymerized polypropylene; 10 parts of syndiotactic polypropylene; 13.7 parts of hydrolysis-resistant chopped glass fibers (14 μm in diameter, 6 mm in length); 8 parts of ethylene-methacrylic acid copolymer; Six parts of maleic anhydride-grafted polypropylene (grafting rate 4%); Antioxidant 1010 1.5 parts; 0.3 parts of pentaerythritol tetra(3-lauryl thiopropionate); 0.5 parts of oleamide.

[0052] The preparation method is as described in Example 1.

[0053] Example 5 This embodiment provides a high and low temperature resistant polypropylene composite material, which, by weight, comprises the following components: Meta-dimethyl polypropylene 63.6 parts; 20 parts of hydrolysis-resistant chopped glass fibers (12μm in diameter, 4mm in length); 10 parts of ethylene-methacrylate metal salt polymer; 5 parts of maleic anhydride-grafted polypropylene (grafting rate 4%); Antioxidant 10100.5 parts; 0.5 parts of pentaerythritol tetra(3-lauryl thiopropionate); 0.4 parts of oleamide.

[0054] The preparation method is as described in Example 1.

[0055] Example 6 This embodiment provides a high and low temperature resistant polypropylene composite material, which, by weight, comprises the following components: Homopolymer polypropylene 63.6 parts; 20 parts of hydrolysis-resistant chopped glass fibers (12μm in diameter, 4mm in length); 10 parts of ethylene vinyl acetate copolymer; 5 parts of maleic anhydride-grafted polypropylene (grafting rate 4%); Antioxidant 10100.5 parts; 0.5 parts of pentaerythritol tetra(3-lauryl thiopropionate); 0.4 parts of oleamide.

[0056] The preparation method is as described in Example 1.

[0057] Comparative Example 1 This comparative example provides a high and low temperature resistant polypropylene composite material, which, by weight, comprises the following components: Homopolymer polypropylene 63.6 parts; 20 parts of ordinary chopped glass fiber; 10 parts of ethylene-methacrylate metal salt polymer; 5 parts of maleic anhydride-grafted polypropylene (grafting rate 4%); Antioxidant 10100.5 parts; 0.5 parts of pentaerythritol tetra(3-lauryl thiopropionate); 0.4 parts of oleamide.

[0058] The preparation method is as described in Example 1.

[0059] Comparative Example 2 This comparative example provides a high and low temperature resistant polypropylene composite material, which, by weight, comprises the following components: 63.6 parts of ordinary random transparent polypropylene; 20 parts of hydrolysis-resistant chopped glass fibers (12μm in diameter, 4mm in length); 10 parts of ethylene-methacrylate metal salt polymer; 5 parts of maleic anhydride-grafted polypropylene (grafting rate 4%); Antioxidant 10100.5 parts; 0.5 parts of pentaerythritol tetra(3-lauryl thiopropionate); 0.4 parts of oleamide.

[0060] The preparation method is as described in Example 1.

[0061] Comparative Example 3 This comparative example provides a high and low temperature resistant polypropylene composite material, which, by weight, comprises the following components: Homopolymer polypropylene 63.6 parts; 20 parts of hydrolysis-resistant chopped glass fibers (12μm in diameter, 4mm in length); 10 copies of POE; 5 parts of maleic anhydride-grafted polypropylene (grafting rate 4%); Antioxidant 10100.5 parts; 0.5 parts of pentaerythritol tetra(3-lauryl thiopropionate); 0.4 parts of oleamide.

[0062] The preparation method is as described in Example 1.

[0063] Comparative Example 4 This comparative example provides a high and low temperature resistant polypropylene composite material, which, by weight, comprises the following components: Homopolymer polypropylene 68.6 parts; 20 parts of hydrolysis-resistant chopped glass fibers (12μm in diameter, 4mm in length); 5 parts of ethylene-methacrylic acid metal salt polymer; 5 parts of maleic anhydride-grafted polypropylene (grafting rate 4%); Antioxidant 10100.5 parts; 0.5 parts of pentaerythritol tetra(3-lauryl thiopropionate); 0.4 parts of oleamide.

[0064] The preparation method is as described in Example 1.

[0065] Comparative Example 5 This comparative example provides a high and low temperature resistant polypropylene composite material, which, by weight, comprises the following components: Homopolymer polypropylene 63.6 parts; 10 parts of hydrolysis-resistant chopped glass fibers (12μm in diameter, 4mm in length); 20 parts of ethylene-methacrylate metal salt polymer; 5 parts of maleic anhydride-grafted polypropylene (grafting rate 4%); Antioxidant 10100.5 parts; 0.5 parts of pentaerythritol tetra(3-lauryl thiopropionate); 0.4 parts of oleamide.

[0066] The preparation method is as described in Example 1.

[0067] Comparative Example 6 This comparative example provides a high and low temperature resistant polypropylene composite material, which, by weight, comprises the following components: Homopolymer polypropylene 63.6 parts; 20 parts of hydrolysis-resistant chopped glass fibers (12μm in diameter, 4mm in length); 10 parts of ethylene-methacrylate metal salt polymer; 5 parts of maleic anhydride-grafted polypropylene (grafting rate 1%). Antioxidant 10100.5 parts; 0.5 parts of pentaerythritol tetra(3-lauryl thiopropionate); 0.4 parts of oleamide.

[0068] The preparation method is as described in Example 1.

[0069] Comparative Example 7 This comparative example provides a high and low temperature resistant polypropylene composite material, whose components and dosages are the same as in Example 1. The preparation method is as follows: Step 1: Premix preparation: Add the polypropylene resin, welding modifier, compatibilizer, antioxidant, heat resistant agent and release agent from the above components into a high-speed mixer and stir at 1200 r / min for 8 min to obtain a uniform premix. Step 2: Compounding and extrusion: The premix and glass fiber are added through the main feed port of the twin-screw extruder. The twin-screw extruder is divided into 14 temperature zones, and the temperature of each zone is set in a gradient: Zone 1 170℃, Zones 2 to 5 190℃, Zones 6 to 10 210℃, Zones 11 to 14 200℃, and the main machine speed is 450 r / min, so that the premix and glass fiber are fully compounded and extruded to obtain the composite material. Step 3: Post-processing: The composite material is cooled in a water tank, pulled by a traction machine, and pelletized by a pelletizer to obtain a high and low temperature resistant polypropylene composite material.

[0070] Table 1. Categories and dosages of components in Examples 1-6

[0071] Table 2. Categories and dosages of components in Comparative Examples 1-7

[0072] The composite material particles prepared in Examples 1-4 and Comparative Examples 1-7 were injection molded into specimens of standard size, and their properties were tested according to standards.

[0073] Welding strength testing method: After the tensile test strips are cut, two strips are stacked together by 1 cm, and then hot-pressed at 200℃ for one minute. After cooling to room temperature for 24 hours, tensile strength test is performed, and the strength of the hot-pressed weld is judged by the value.

[0074] Water resistance test: After boiling the tensile specimen in water for 24 hours, the tensile strength was tested after cooling to room temperature.

[0075] Transparency test method: Inject a 2mm thick square box, fill it with water, insert a steel ruler, and observe the clarity of the scale from millimeters to centimeters from the outside. The level is determined by whether the reading can be clearly seen.

[0076] Table 2 shows the performance test results of the samples prepared in Examples 1-6 and Comparative Examples 1-7.

[0077] Table 2 shows the performance test results of the samples prepared in Examples 1-6 and Comparative Examples 1-7.

[0078] The transparency level is evaluated based on whether the steel ruler scale can be clearly observed, with A+++ being the best and B being the basic acceptable level.

[0079] As shown in Table 2, the products prepared in Examples 1-6 possess excellent mechanical properties and heat resistance, as well as excellent weldability. After boiling in water, their tensile properties are retained very well, and they exhibit high transparency. Compared to Example 1, Comparative Example 1, using ordinary chopped fibers, showed a decrease in mechanical properties, weld tensile strength, and water resistance, indicating that the hydrolysis-resistant glass fiber not only improved the product's hydrolysis resistance but also synergistically enhanced other properties. Compared to Example 1, Comparative Example 2, using ordinary random transparent polypropylene, showed a decrease in tensile strength, flexural strength, flexural modulus, heat resistance, weld strength, and water resistance, demonstrating the importance of matrix resin selection. Compared to Example 1, Comparative Example 3 used POE as a weld modifier, resulting in a significant decrease in weldability, as well as a decrease in water resistance, heat resistance, and tensile strength, demonstrating the multifaceted advantages of the weld modifier selected in this invention. Compared to Example 1, Comparative Example 4 used a lower amount of welding modifier, with a welding modifier-to-glass fiber ratio of 1:4. Compared to Example 1, Comparative Example 5 had a welding modifier-to-glass fiber ratio of 2:1. This imbalance in the ratio of welding modifier to glass fiber resulted in all properties being lower than those of the product in Example 1. Compared to Example 1, Comparative Example 6 had a maleic anhydride-grafted PP grafting rate of only 1%, leading to insufficient interfacial bonding strength. When the material was under load, stress could not be efficiently transferred from the relatively flexible resin matrix to the high-strength glass fiber, preventing the glass fiber from realizing its reinforcing potential. The overall material exhibited decreased strength, rigidity, and toughness. Compared to Example 1, Comparative Example 7 had a different glass fiber feeding location, resulting in a decrease in all properties of Comparative Example 7.

[0080] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any modifications or equivalent changes made based on the technical essence of the present invention shall still fall within the scope of protection claimed by the present invention.

Claims

1. A high and low temperature resistant polypropylene composite material, characterized in that, By weight, it includes the following components: 40-70 parts of polypropylene resin; 5-15 parts of welding improver; 5-45 parts glass fiber; Antioxidant 0.5-1.5 parts; 3-8 parts compatibilizer; Release agent 0.1-1 part; 0.2-0.5 parts of heat resistant agent; The high and low temperature resistant polypropylene composite material has a heat distortion temperature ≥122℃ and a low-temperature simply supported beam notched impact strength ≥11KJ / m. 2 .

2. The high and low temperature resistant polypropylene composite material according to claim 1, characterized in that, The polypropylene resin is one or more of homopolymer polypropylene, copolymer polypropylene, and syndiotactic polypropylene.

3. The high and low temperature resistant polypropylene composite material according to claim 1, characterized in that, The glass fiber is a hydrolysis-resistant chopped glass fiber with a diameter of 10-14 μm and a length of 3-6 mm.

4. The high and low temperature resistant polypropylene composite material according to claim 1, characterized in that, The antioxidant is one or more of hindered phenolic antioxidants and phosphite antioxidants.

5. The high and low temperature resistant polypropylene composite material according to claim 1, characterized in that, The compatibilizer is maleic anhydride-grafted polypropylene with a grafting rate of 2-5%.

6. The high and low temperature resistant polypropylene composite material according to claim 1, characterized in that, The welding modifier is selected from one or more of the following: ethylene-propylene random copolymer, ethylene-methacrylic acid metal salt polymer, ethylene-methacrylic acid copolymer, and ethylene-vinyl acetate copolymer.

7. The high and low temperature resistant polypropylene composite material according to claim 1, characterized in that, The heat-resistant agent is selected from thioether antioxidants and thioester antioxidants.

8. The high and low temperature resistant polypropylene composite material according to claim 1, characterized in that, The release agent is selected from oleamide, erucamide, stearate, or silicone composition.

9. A method for preparing a high and low temperature resistant polypropylene composite material as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Mix polypropylene resin, welding modifier, antioxidant, compatibilizer, release agent and heat resistant agent to obtain a premix; S2. The premixed material is added through the main feed port of a twin-screw extruder, and the glass fiber is added through the side feed port, so that the premixed material and glass fiber are mixed and extruded in the twin-screw extruder to obtain a composite material; S3. The composite material is cooled, drawn, and pelletized in a water tank to obtain a high and low temperature resistant polypropylene composite material.

10. An application of the high and low temperature resistant polypropylene composite material as described in any one of claims 1-8, characterized in that, The polypropylene composite material is used in water tanks.

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