Polypropylene composite and method for producing the same

Abstract

The application belongs to the technical field of plastic preparation, and particularly relates to a polypropylene composite material and a preparation method thereof. The polypropylene composite material provided by the application comprises the following raw materials in mass fractions: 65-75 parts of polypropylene, 18-22 parts of filler master batch, 2-4 parts of compatilizer and 0.2-0.3 parts of antioxidant; the filler master batch comprises functional additives and acrylate elastomers wrapping the functional additives; the functional additives comprise modified silicon micro powder, modified kaolinite, talcum powder and cordierite; the modified silicon micro powder comprises silicon micro powder coated with a silane coupling agent; and the modified kaolinite comprises kaolinite coated with a silane coupling agent. The polypropylene composite material provided by the application simultaneously has the advantages of high flexural modulus, high impact strength and high heat distortion temperature.

Description

Technical Field

[0001] This invention belongs to the field of plastic preparation technology, specifically relating to a polypropylene composite material and its preparation method. Background Technology

[0002] Polypropylene (PP), as an important general-purpose thermoplastic, is widely used in various fields such as the automotive industry, home appliances, packaging, construction, and medical devices due to its excellent comprehensive properties, such as good processability, low density, high chemical resistance, and relatively low cost. However, unmodified polypropylene still has certain performance limitations in practical applications, mainly manifested in low flexural modulus, insufficient impact strength, and significant brittleness, especially at low temperatures. Furthermore, its heat deflection temperature (HDT) is relatively low, typically between 100 and 110°C, limiting its application in high-temperature environments or structural components requiring both high rigidity and toughness. Therefore, how to synergistically improve the rigidity, toughness, and heat resistance of polypropylene through effective modification methods has become a long-term research hotspot in the field of polymer materials.

[0003] In recent years, research on the modification of polypropylene has mainly focused on copolymerization modification, blending modification, filler reinforcement, and composite modification. Among these, the introduction of inorganic fillers (such as talc, calcium carbonate, and silicates) can effectively improve the flexural modulus and HDT of polypropylene, but this often comes with a significant decrease in material toughness, especially impact strength, leading to embrittlement and making it difficult to meet the comprehensive mechanical performance requirements of structural components. On the other hand, elastomer toughening (such as ethylene propylene rubber (EPR) and POE) can significantly improve impact performance, but usually at the cost of sacrificing stiffness and heat distortion temperature, resulting in material softening and decreased dimensional stability. Although some studies have attempted to achieve a performance balance through multiphase composite systems (such as synergistic toughening and reinforcement using rigid particles and elastomers) or advanced methods such as in-situ fiber formation and microlayered structure design, most methods, while improving one or two properties, cannot avoid negatively impacting other properties, failing to achieve a simultaneous and significant improvement in flexural modulus, impact strength, and heat distortion temperature.

[0004] Furthermore, existing modification processes still face technical bottlenecks in areas such as interfacial compatibility control, filler dispersion uniformity, and crystallization behavior control. For example, weak bonding between the filler and matrix interface can easily lead to stress concentration, while uneven elastomer distribution may result in localized stress relaxation or phase separation, thus affecting the synergistic optimization of overall performance. Although some studies have reported improvements in crystal structure by introducing compatibilizers, employing multi-step processing techniques, or controlling the cooling rate, these methods are often complex, costly, and offer limited performance improvements, making it difficult to achieve large-scale, stable industrial production.

[0005] It is worth noting that although patents and literature have claimed to have developed "high-stiffness, high-toughness, and heat-resistant" polypropylene materials, the performance improvements are mostly relative, lacking a systematic solution that achieves a significant synergistic enhancement of all three properties without significantly sacrificing any key performance characteristic. This is especially true in emerging application areas such as automotive lightweighting and 5G communication equipment structural components, where materials simultaneously possessing high flexural modulus (>1500MPa) and high notched impact strength (>50kJ / m²) are crucial. 2 The urgent need for high heat distortion temperature (>135℃) and other properties of polypropylene has been highlighted, but existing technologies cannot reliably meet these comprehensive indicators. Therefore, developing a novel modification method that can synergistically regulate the rigidity, toughness, and heat resistance of polypropylene, especially through innovation in material design and preparation processes to achieve multi-scale structural regulation and synergistic performance optimization, remains a key scientific problem and technical challenge in the current research on high-performance polypropylene.

[0006] In summary, although significant progress has been made in the research of modified polypropylene plastics, existing technologies still have obvious shortcomings in achieving a simultaneous and substantial improvement in flexural modulus, impact strength, and heat distortion temperature. A universally applicable, feasible, cost-effective, and stable preparation method has yet to be developed, hindering the further expansion of polypropylene in high-end manufacturing. Therefore, in-depth exploration of multi-factor synergistic modification mechanisms, construction of novel composite structural systems, and development of efficient and controllable preparation processes have become urgent needs and important research directions for promoting the development of polypropylene materials towards high performance and functionalization. Summary of the Invention

[0007] The purpose of this invention is to provide a polypropylene composite material and its preparation method. The polypropylene composite material provided by this invention simultaneously possesses the advantages of high flexural modulus, high impact strength, and high heat distortion temperature.

[0008] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a polypropylene composite material comprising the following raw materials in parts by weight: The mixture contains 65-75 parts polypropylene, 18-22 parts filler masterbatch, 2-4 parts compatibilizer, and 0.2-0.3 parts antioxidant. The filler masterbatch includes a functional additive and an acrylate elastomer encapsulating the functional additive; The functional additives include modified silica powder, modified kaolinite, talc, and cordierite; The modified silicon micro powder includes silicon micro powder coated with a silane coupling agent; The modified kaolinite includes kaolinite coated with a silane coupling agent.

[0009] Preferably, by mass parts, the functional additives include 10-15 parts of modified silica powder, 15-20 parts of modified kaolinite, 35-40 parts of talc powder and 7-10 parts of cordierite.

[0010] Preferably, the silane coupling agent coated in the silica micropowder includes γ-aminopropyltriethoxysilane; The particle size of the silicon micropowder is 10~20μm; The mass of the silane coupling agent is 1.8 to 2.2% of the mass of the silicon micropowder.

[0011] Preferably, the silane coupling agent coating kaolinite comprises γ-aminopropyltriethoxysilane; The kaolinite has a particle size of 10~20μm; The mass of the silane coupling agent is 1.8 to 2.2% of the mass of kaolinite.

[0012] Preferably, the particle size of the talc powder is 10~20μm; The particle size of the cordierite is 10~20μm.

[0013] Preferably, the acrylate elastomer includes Metalatn S-2200 elastomer; The mass ratio of the acrylate elastomer to the functional additive is 30~40:60~70.

[0014] Preferably, the compatibilizer comprises maleic anhydride-grafted polypropylene; The antioxidant includes antioxidant 1010.

[0015] The present invention also provides a method for preparing the polypropylene composite material described in the above technical solution, comprising the following steps: Acrylic elastomers and functional additives are mixed and subjected to a first extrusion to obtain filler masterbatch; Polypropylene, filler masterbatch, compatibilizer and antioxidant are mixed and subjected to a second extrusion to obtain the polypropylene composite material.

[0016] Preferably, the temperature of the first extrusion is 180~220℃ and the screw speed is 200~400rpm.

[0017] Preferably, the temperature of the second extrusion is 180~220℃ and the screw speed is 200~400rpm.

[0018] Compared with the prior art, the beneficial effects of the present invention include: This invention overcomes the bottleneck of the trade-off between rigidity, toughness, and heat resistance in traditional polypropylene modification. It achieves these effects through multi-scale interface design, filler synergy, and elastomer topology control. Specifically, this invention modifies silica fume and kaolinite with a silane coupling agent, retaining the original activity of talc and cordierite. This promotes the preferential and uniform coating of acrylate elastomers onto the surface of the mixed filler to form a "core-shell" dispersed phase. The high thermal stability of talc layers and cordierite constructs a rigid framework and inhibits thermal deformation. The elastomer layer absorbs impact energy and inhibits crack propagation. Furthermore, a compatibilizer forms a covalent bond bridge between the filler and the polypropylene matrix. Ultimately, this invention overcomes the bottleneck of the traditional modification's trade-off between rigidity, toughness, and heat distortion temperature, achieving a flexural modulus >1700MPa and an impact strength >55kJ / m. 2 The simultaneous and significant improvement in heat distortion temperature >145℃ overcomes the technical deficiencies in this field and has good application prospects. Detailed Implementation

[0019] This invention provides a polypropylene composite material comprising the following raw materials in parts by weight: The mixture contains 65-75 parts polypropylene, 18-22 parts filler masterbatch, 2-4 parts compatibilizer, and 0.2-0.3 parts antioxidant. The filler masterbatch includes a functional additive and an acrylate elastomer encapsulating the functional additive; The functional additives include modified silica powder, modified kaolinite, talc, and cordierite; The modified silicon micro powder includes silicon micro powder coated with a silane coupling agent; The modified kaolinite includes kaolinite coated with a silane coupling agent.

[0020] The raw materials for preparing the polypropylene composite material provided by this invention, by weight, include 65-75 parts of polypropylene, specifically 65 parts, 68 parts, 70 parts, 72 parts, and 75 parts. In this invention, the polypropylene is preferably injection molding grade polypropylene; the melt index of the polypropylene is preferably 23-25 ​​g / 10 min, and it is purchased from Juju International Trading (Shanghai) Co., Ltd.

[0021] Based on the mass fraction of polypropylene, the raw materials for preparing the polypropylene composite material provided by the present invention include 18-22 parts of filler masterbatch, specifically 18 parts, 19 parts, 20 parts, 21 parts, and 22 parts. In the present invention, the filler masterbatch includes functional additives and acrylate elastomers encapsulating the functional additives; the functional additives include modified silica powder, modified kaolinite, talc, and cordierite; the modified silica powder includes silica powder coated with a silane coupling agent; the modified kaolinite includes kaolinite coated with a silane coupling agent.

[0022] In this invention, the functional additives preferably include 10-15 parts of modified silica powder, 15-20 parts of modified kaolinite, 35-40 parts of talc powder, and 7-10 parts of cordierite, by mass.

[0023] The functional additive provided by this invention preferably comprises 10-15 parts of modified silicon micropowder by weight, specifically 10, 11, 12, 13, 14, or 15 parts. In this invention, the silane coupling agent in the silicon micropowder coated with the silane coupling agent preferably comprises γ-aminopropyltriethoxysilane (KH-550); the particle size of the silicon micropowder is preferably 10-20 μm; the mass of the silane coupling agent is preferably 1.8-2.2% of the mass of the silicon micropowder, more preferably 2%. In this invention, the silicon micropowder coated with the silane coupling agent is preferably obtained through preparation; the preparation method preferably includes: spraying an ethanol solution of the silane coupling agent onto preheated silicon micropowder for coating, thereby obtaining the silicon micropowder coated with the silane coupling agent. In this invention, before preheating, the silicon micropowder is preferably dried at a temperature of 105°C for 2 hours; the preheating temperature is preferably 70°C; and the coating is preferably carried out under stirring conditions at a temperature of 80°C for 1 hour.

[0024] Based on the mass fraction of the modified silica powder, the functional additive provided by the present invention preferably includes 15-20 parts of modified kaolinite, specifically 15, 16, 17, 18, 19, or 20 parts. In the present invention, the silane coupling agent coating the kaolinite preferably includes γ-aminopropyltriethoxysilane; the particle size of the kaolinite is preferably 10-20 μm; the mass of the silane coupling agent is preferably 1.8-2.2% of the mass of the kaolinite, more preferably 2%. In the present invention, the silane coupling agent coating the kaolinite is preferably obtained through preparation; the preparation method preferably includes: spraying an ethanol solution of the silane coupling agent onto preheated kaolinite for coating, thereby obtaining the silane coupling agent-coated kaolinite. In this invention, before preheating, the kaolin is preferably dried at a temperature of 105°C for 2 hours; the preheating temperature is preferably 70°C; and the coating is preferably carried out under stirring conditions at a temperature of 80°C for 1 hour.

[0025] Based on the mass fraction of the modified silica powder, the functional additive provided by the present invention preferably includes 35-40 parts of talc powder, specifically 35, 36, 37, 38, 39, or 40 parts. In the present invention, the particle size of the talc powder is preferably 10-20 μm.

[0026] Based on the mass fraction of the modified silica powder, the functional additive provided by the present invention preferably includes 7 to 10 parts of cordierite, specifically 7, 8, 9, or 10 parts. In the present invention, the particle size of the cordierite is preferably 10 to 20 μm.

[0027] In this invention, the preparation method of the functional additive is preferably to obtain it by mixing the included components; before mixing, it is also preferred to dry the talc powder and cordierite separately; the drying temperature is preferably 105°C and the drying time is preferably 2 hours.

[0028] Based on the mass fraction of polypropylene, the raw materials for preparing the polypropylene composite material provided by the present invention include 2 to 4 parts of a compatibilizer, specifically 2, 3, or 4 parts. In the present invention, the compatibilizer preferably includes maleic anhydride-grafted polypropylene.

[0029] Based on the mass fraction of polypropylene, the raw materials for preparing the polypropylene composite material provided by the present invention include 0.2 to 0.3 parts of antioxidant. In the present invention, the antioxidant preferably includes antioxidant 1010.

[0030] In this invention, the acrylate elastomer preferably includes Metalatn S-2200 elastomer; the mass ratio of the acrylate elastomer to the functional additive is preferably 30~40:60~70, specifically 30:70, 32:68, 34:66, 35:65, 38:62, or 40:60.

[0031] The present invention also provides a method for preparing the polypropylene composite material described in the above technical solution, comprising the following steps: Acrylic elastomers and functional additives are mixed and subjected to a first extrusion to obtain filler masterbatch; Polypropylene, filler masterbatch, compatibilizer and antioxidant are mixed and subjected to a second extrusion to obtain the polypropylene composite material.

[0032] In this invention, the temperature of the first extrusion is preferably 180~220℃, more preferably 200℃; the screw speed is preferably 200~400rpm, more preferably 300rpm; the first extrusion is carried out using a twin-screw extruder.

[0033] In this invention, the mixing of polypropylene, filler masterbatch, compatibilizer, and antioxidant is preferably carried out under stirring conditions, and the stirring time is preferably 5 minutes; the temperature of the second extrusion is preferably 180~220℃, more preferably 200℃; the screw speed is preferably 200~400 rpm, more preferably 300 rpm. In this invention, after the second extrusion, water cooling pelletizing is also preferably performed.

[0034] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0035] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0036] The raw materials used in the following examples and comparative examples

[0037] Example 1 Preparation of modified silica powder: Preheat silica powder (dried at 105℃ for 2 hours before use) to 70℃, spray anhydrous ethanol solution of KH-550 evenly onto the preheated silica powder (the mass of KH-550 is 2% of the mass of silica powder), stir at 80℃ for 1 hour to obtain modified silica powder. Modified kaolinite: Preheat kaolinite (dried at 105℃ for 2 hours before use) to 70℃, and spray anhydrous ethanol solution of KH-550 evenly onto the preheated kaolinite (the mass of KH-550 is 2% of the mass of kaolinite). Stir at 80℃ for 1 hour to obtain modified kaolinite. Talc and cordierite should be dried at 105℃ for 2 hours before use. Modified silica powder, modified kaolinite, talc powder, and cordierite were mixed in a mass ratio of 12:18:38:9 to obtain a mixed filler. The Metalatn S-2200 elastomer and the mixed filler were extruded using a twin-screw extruder at a mass ratio of 30:70. The temperature was set at 200℃ and the screw speed at 300rpm, so that the Metalatn S-2200 elastomer could be fully coated on the surface of the mixed filler to obtain filler masterbatch. Polypropylene resin, filler masterbatch, PP-g-MAH and antioxidant 1010 were premixed at a mass ratio of 70:20:3:0.2 (mixed in a high-speed mixer for 5 minutes). Then, a twin-screw extruder was used to melt-blend and extrude the mixture at a temperature of 200℃ and a screw speed of 300 rpm. After that, the mixture was water-cooled and pelletized to obtain the polypropylene composite material.

[0038] Example 2 Modified silica powder and modified kaolinite were obtained according to Example 1, and talc powder and cordierite were dried. Modified silica powder, modified kaolinite, talc powder, and cordierite were mixed in a mass ratio of 15:20:40:10 to obtain a mixed filler. The Metalatn S-2200 elastomer and the mixed filler were extruded using a twin-screw extruder at a mass ratio of 40:60. The temperature was set at 200℃ and the screw speed at 300rpm, so that the Metalatn S-2200 elastomer could be fully coated on the surface of the mixed filler to obtain filler masterbatch. Polypropylene resin, filler masterbatch, PP-g-MAH and antioxidant 1010 were premixed in a mass ratio of 75:22:4:0.3 (mixed for 5 minutes in a high-speed mixer). Then, a twin-screw extruder was used to perform melt blending extrusion at a temperature of 200℃ and a screw speed of 300 rpm. After water cooling and pelletizing, the polypropylene composite material was obtained.

[0039] Example 3 Modified silica powder and modified kaolinite were obtained according to Example 1, and talc powder and cordierite were dried. Modified silica powder, modified kaolinite, talc powder, and cordierite were mixed in a mass ratio of 10:15:35:7 to obtain a mixed filler. The Metalatn S-2200 elastomer and the mixed filler were extruded using a twin-screw extruder at a mass ratio of 35:65. The temperature was set at 200℃ and the screw speed at 300rpm, so that the Metalatn S-2200 elastomer could be fully coated on the surface of the mixed filler to obtain filler masterbatch. Polypropylene resin, filler masterbatch, PP-g-MAH and antioxidant 1010 were premixed at a mass ratio of 65:18:2:0.2 (mixed for 5 minutes in a high-speed mixer). Then, a twin-screw extruder was used to perform melt blending extrusion at a temperature of 200℃ and a screw speed of 300 rpm. After water cooling and pelletizing, the polypropylene composite material was obtained.

[0040] Comparative Example 1 A polypropylene composite material was prepared according to Example 1, without the addition of cordierite.

[0041] Comparative Example 2 A polypropylene composite material was prepared according to Example 1, wherein talc and cordierite were modified. Specifically: Preparation of modified talc: Preheat talc (dried at 105℃ for 2 hours before use) to 70℃, and spray anhydrous ethanol solution of KH-550 evenly onto the preheated talc (the mass of KH-550 is 2% of the mass of talc). Stir at 80℃ for 1 hour to obtain modified talc. Preparation of modified cordierite: Cordierite (dried at 105℃ for 2 hours before use) is preheated to 70℃. Anhydrous ethanol solution of KH-550 is evenly sprayed onto the preheated cordierite (the mass of KH-550 is 2% of the mass of cordierite). The mixture is stirred at 80℃ for 1 hour to obtain modified cordierite.

[0042] Comparative Example 3 A polypropylene composite material was prepared according to Example 1, wherein the kaolinite was not modified.

[0043] Performance testing The products obtained in Examples 1-3 and Comparative Examples 1-3 were tested for flexural modulus, impact strength, and heat distortion temperature. The test standards used were GB / T 9341, GB / T 1843, and GB / T 1634, respectively. The test results are shown in Table 1.

[0044] Table 1. Performance test results of the composite materials in Examples 1-3 and Comparative Examples 1-3

[0045] As shown in Table 1, the selection of modification methods and the design of modification schemes for the four filler materials are the key to the invention's ability to simultaneously improve the flexural modulus, impact strength, and heat distortion temperature of polypropylene plastics.

[0046] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A polypropylene composite material, characterized in that, The preparation raw materials include the following parts by weight: The mixture contains 65-75 parts polypropylene, 18-22 parts filler masterbatch, 2-4 parts compatibilizer, and 0.2-0.3 parts antioxidant. The filler masterbatch includes a functional additive and an acrylate elastomer encapsulating the functional additive; The functional additives include modified silica powder, modified kaolinite, talc, and cordierite; The modified silicon micro powder includes silicon micro powder coated with a silane coupling agent; The modified kaolinite includes kaolinite coated with a silane coupling agent.

2. The polypropylene composite material according to claim 1, characterized in that, The functional additives, by mass, include 10-15 parts modified silica powder, 15-20 parts modified kaolinite, 35-40 parts talc powder, and 7-10 parts cordierite.

3. The polypropylene composite material according to claim 1, characterized in that, The silane coupling agent in the silane-coated silica powder includes γ-aminopropyltriethoxysilane; The particle size of the silicon micropowder is 10~20μm; The mass of the silane coupling agent is 1.8 to 2.2% of the mass of the silicon micropowder.

4. The polypropylene composite material according to claim 1, characterized in that, The silane coupling agent coating kaolinite includes γ-aminopropyltriethoxysilane; The kaolinite has a particle size of 10~20μm; The mass of the silane coupling agent is 1.8 to 2.2% of the mass of kaolinite.

5. The polypropylene composite material according to claim 1, characterized in that, The talc powder has a particle size of 10~20μm; The particle size of the cordierite is 10~20μm.

6. The polypropylene composite material according to claim 1, characterized in that, The acrylate elastomers include Metalatn S-2200 elastomer; The mass ratio of the acrylate elastomer to the functional additive is 30~40:60~70.

7. The polypropylene composite material according to claim 1, characterized in that, The compatibilizer comprises maleic anhydride-grafted polypropylene. The antioxidant includes antioxidant 1010.

8. A method for preparing the polypropylene composite material according to any one of claims 1 to 7, characterized in that, Includes the following steps: Acrylic elastomers and functional additives are mixed and subjected to a first extrusion to obtain filler masterbatch; Polypropylene, filler masterbatch, compatibilizer and antioxidant are mixed and subjected to a second extrusion to obtain the polypropylene composite material.

9. The preparation method according to claim 8, characterized in that, The temperature of the first extrusion is 180~220℃, and the screw speed is 200~400rpm.

10. The preparation method according to claim 8, characterized in that, The temperature of the second extrusion is 180~220℃, and the screw speed is 200~400rpm.

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