Low-density high-performance talcum powder filled modified polypropylene material and preparation method thereof

Abstract

The invention provides a low-density high-performance talcum powder filled modified polypropylene material and a preparation method thereof, and belongs to the field of high polymer materials. The polypropylene material comprises the following raw materials in parts by weight: 50-80 parts of polypropylene, 5-15 parts of a toughening agent, 5-20 parts of talcum powder, 1-3 parts of a compatilizer, 1-3 parts of graphene and 0.5-1.5 parts of a nucleating agent. Through the rigidity enhancement of talcum powder and the nano synergistic effect of graphene, and in combination with an interface modification technology, the multi-dimensional performance breakthrough of the material under the low density of 0.96-0.99 g / cm < 3 > is realized, and meanwhile, the material has excellent surface hardness and wear resistance. The innovative gradient dispersion process ensures that the nano filler is uniformly distributed in a matrix, and is particularly suitable for automobile parts with strict requirements on light weight and reliability, such as an automobile instrument panel framework, a door panel module, an engine peripheral assembly and the like. Compared with traditional mineral-filled PP, the weight of the material is reduced by 15% or above while the injection molding machinability is kept, and an ideal light-weight and high-strength solution is provided for new energy automobile structural parts.

Description

Technical Field

[0001] The present invention belongs to the field of polymer materials, and particularly relates to a low-density and high-performance talc-filled modified polypropylene material and a preparation method thereof, which are particularly suitable for the fields of automotive lightweight components, interior trim parts and other automotive materials. Background Art

[0002] With the development of the automotive industry towards lightweight, energy-saving and environmental protection, the lightweight and high-performance of automotive materials have become a major trend in the industry. Polypropylene (PP), as a lightweight, chemically resistant and easy-to-process engineering plastic, is widely used in the production of automotive parts. However, the mechanical properties and thermal stability of traditional polypropylene materials are poor, which limits their application in fields with higher requirements such as automotive lightweight and high temperature resistance. Therefore, how to improve the comprehensive performance of polypropylene through modification while maintaining a low density is a current research hotspot.

[0003] Graphene, as a two-dimensional material with excellent mechanical properties, thermal conductivity and electrical conductivity, has received extensive attention as a toughening and reinforcing material in polymers. Talc, as an inorganic filler, can improve the rigidity, thermal stability and wear resistance of polypropylene. Nucleating agents can promote the crystallization of polypropylene, thereby improving the heat distortion temperature and mechanical properties of the material. However, the dispersibility and compatibility of different components such as graphene, talc and nucleating agents in the polypropylene matrix are poor, and phenomena such as filler agglomeration and uneven dispersion are likely to occur, affecting the comprehensive performance of the final material.

[0004] Therefore, the present invention has successfully developed a polypropylene composite material with low density, excellent mechanical properties and good thermal stability by optimizing the ratio and preparation method of graphene, talc, nucleating agent and compatibilizer, which is particularly suitable for lightweight components and interior trim parts in the automotive industry and other fields. Summary of the Invention

[0005] The purpose of the present invention is to provide a low-density and high-performance talc-filled modified polypropylene material and a preparation method thereof. This material can maintain a low density while improving the mechanical properties, thermal stability and wear resistance of polypropylene, and has good processing performance, and is suitable for fields such as automotive lightweight components and interior trim parts.

[0006] In the first aspect of the present invention, it relates to a talc-filled modified polypropylene material, which comprises the following raw materials in parts by weight:

[0007]

[0008] Optionally, the polypropylene is polypropylene pretreated by plasma, with a treatment time of 5 - 15 minutes and a power of 100 - 300 W, so as to activate the resin surface and enhance its bonding force with other components; the weight-average molecular weight (Mw) of the polypropylene is between 200,000 and 500,000, and the molecular weight distribution index (Mw / Mn) is 2.5 - 4.0, ensuring good mechanical properties and processing performance.

[0009] Optionally, the graphene is graphene pretreated by ultrasonic waves.

[0010] Optionally, the talc powder is talc powder with crystal form regulated. The talc powder is special talc powder with a lamellar structure. First, it is ultrasonically dispersed in a solution containing a coupling agent, with an ultrasonic power of 200 - 400 W and a time of 10 - 20 minutes. The coupling agent is a silane coupling agent. Subsequently, it is subjected to crystal form regulation treatment under high temperature and high pressure, with a temperature of 300 - 400 °C, a pressure of 5 - 10 MPa, and a treatment time of 30 - 60 minutes, making its lamellar structure more regular and orderly and optimizing the composite effect with PP.

[0011] Optionally, the compatibilizer is SEBS.

[0012] Optionally, the toughening agent is polymer microspheres with a core - shell structure. The inner core is polybutadiene rubber, and the outer core is a polypropylene graft copolymer with good compatibility with PP, which is prepared by emulsion polymerization.

[0013] Optionally, the nucleating agent is zinc stearate nucleating agent.

[0014] Optionally, it further includes 0.1 - 0.5 parts by weight of antioxidant and 0.1 - 1 part by weight of ultraviolet light absorber.

[0015] Optionally, the ultraviolet light absorber is a hindered amine light stabilizer; the antioxidant is a composite antioxidant, which is a combination of 1076 and 168.

[0016] The second aspect of the present invention relates to a preparation method of a talc powder filled and modified polypropylene material, including the following steps:

[0017] 1), Pretreat the graphene by ultrasonic waves;

[0018] 2), Premix the pretreated polypropylene resin, talc powder with crystal form regulated, and ultrasonically treated graphene under high - speed stirring, with a stirring speed of 1500 - 2500 r / min and a time of 10 - 15 minutes, initially constructing the bonding basis between the two;

[0019] 3), Add the core - shell structure polymer microspheres, antioxidant, light stabilizer, nucleating agent, etc. to the side feeding port of a twin - screw extruder, and add the polypropylene resin and talc powder premix from the main feeding port;

[0020] 4) The twin-screw extruder uses a special combined screw, which includes multiple kneading blocks and reverse-thread elements. The length-diameter ratio of the screw is 50 - 60; the screw rotation speed is 400 - 600 r / min, and the extrusion temperature is set at 190 - 230 °C. It is divided into 8 heating zones in total, and the temperatures of each zone vary in a gradient manner to achieve sufficient mixing and reaction;

[0021] 5) During the extrusion process, a high-frequency pulsed electric field is applied, with an electric field strength of 1 - 3 kV / cm and a frequency of 10 - 30 kHz, to promote the formation of an orderly oriented micro-structure of talc flakes and polymer microspheres in the PP matrix;

[0022] 6) After water-cooling, strand pelletizing, the target material is obtained.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. Enhancing the mechanical properties of the material

[0025] High strength and rigidity: As a high-strength and rigid nanomaterial, graphene's excellent reinforcing effect can significantly improve the tensile strength, flexural stiffness, and impact toughness of polypropylene. Especially in a low-temperature environment, the addition of graphene can effectively improve the low-temperature performance of polypropylene, making it exhibit better mechanical properties in automotive components.

[0026] Improving impact toughness: The dispersion of graphene can strengthen the internal structure of the material, reduce the brittleness that talc powder may bring, and improve the impact resistance and crack propagation resistance of the polypropylene material.

[0027] Through the rigid reinforcement of talc powder and the nano-synergistic effect of graphene, combined with the interface modification technology, a multi-dimensional performance breakthrough of the material at a low density of 0.96 - 0.99 g / cm 3 is achieved, while also having excellent surface hardness and wear resistance characteristics.

[0028] 2. Optimizing thermal stability

[0029] Excellent high-temperature resistance: The introduction of the nucleating agent can improve the crystallization performance of polypropylene, making it exhibit higher thermal stability and dimensional stability in a high-temperature environment. The addition of graphene further enhances the thermal stability and thermal aging resistance of polypropylene, especially suitable for high-temperature components inside and outside automobiles.

[0030] Improving thermal aging performance: Graphene can form a relatively strong network structure in polypropylene, further enhancing the durability of the material in a long-term high-temperature environment and reducing the performance degradation caused by thermal aging.

[0031] 3. Reducing the material density and enhancing the lightweight effect

[0032] Reduced density: The modification of graphene and talcum powder enables polypropylene to achieve a lower density while maintaining or enhancing its mechanical properties. This is particularly important for automotive materials as the lightweighting of automotive components is a crucial means to improve vehicle fuel efficiency and reduce emissions.

[0033] Lightweighting advantage: Compared with traditional talcum powder modified polypropylene, the addition of graphene can effectively reduce the density of the material, thus achieving better lightweighting effects and meeting the requirements of modern vehicles for material lightweighting.

[0034] The innovative gradient dispersion process ensures the uniform distribution of nano-fillers in the matrix, which is particularly suitable for automotive components with stringent requirements for lightweighting and reliability, such as automotive instrument panel skeletons, door panel modules, and engine peripheral components. While maintaining injection moldability, this material weighs more than 15% less than traditional mineral-filled PP, providing an ideal lightweight and high-strength solution for new energy vehicle structural components.

[0035] 4. Improvement of material processing performance

[0036] Good processing fluidity: By introducing a compatibilizer, the compatibility between talcum powder and the polypropylene matrix is significantly improved, reducing the uneven dispersion of talcum powder in polypropylene. This not only enhances the fluidity of the material but also reduces defects such as bubbles and cracks during the molding process, ensuring the surface quality of the molded parts.

[0037] Reduced processing difficulty: Due to the better fluidity of the modified polypropylene during processing such as extrusion and injection molding, it can be more easily precision molded and mass-produced, reducing production costs and process difficulties.

[0038] 5. Enhancement of environmental friendliness

[0039] Non-toxic and environmentally friendly materials: The graphene, nucleating agent, and compatibilizer used in this invention are all non-toxic and environmentally friendly materials, meeting the strict requirements of the modern automotive industry for environmentally friendly materials. The use of the materials not only improves performance but also reduces the impact on the environment.

[0040] Meeting the requirements of automotive lightweighting and green manufacturing: The lightweighting, energy-saving, and low-carbon emission characteristics of the modified polypropylene material meet the current automotive industry's demand for green and environmentally friendly materials. Specific implementation methods

[0041] The following are the specific implementation methods for modifying polypropylene with graphene, nucleating agent, compatibilizer, and talcum powder provided by this invention, which details the specific operations and experimental conditions for each step.

[0042] 1. Dispersion treatment of graphene:

[0043] Mix graphene powder with an appropriate amount of solvent (such as dichloromethane) to obtain a graphene solution.

[0044] Use an ultrasonic disperser to ultrasonically treat the solution, with the power set to

[0045] 300 W and the treatment time being 30 minutes to ensure that the graphene is fully dispersed and avoid agglomeration.

[0046] 2. Crystal form regulation treatment of talcum powder:

[0047] Disperse special talcum powder with a lamellar structure in a solution containing a coupling agent by ultrasonic waves, with an ultrasonic power of 300 W and a treatment time of 20 minutes. The coupling agent is a silane coupling agent. Subsequently, perform crystal form regulation treatment under high temperature and high pressure, with a temperature of 350 °C, a pressure of 10 MPa, and a treatment time of 40 minutes to make its lamellar structure more regular and orderly and optimize the composite result with PP.

[0048] 3. Mixing of each component

[0049] Pre-mix the nucleating agent (zinc stearate), compatibilizer (SEBS), talcum powder, and polypropylene particles. Use a low-speed stirrer to mix these components evenly to ensure that the nucleating agent and compatibilizer can be effectively distributed on the surface of the polypropylene particles.

[0050] After the preparatory work is completed, carry out melt blending according to the formulation and ratio of the following examples.

[0051] 4. Melt blending:

[0052] Use a twin-screw extruder for melt blending, set the temperature range to 190 °C to 230 °C, and the screw speed to 500 revolutions per minute. Feed the graphene solution together with the pre-mixed polypropylene, talcum powder, nucleating agent, and compatibilizer into the extruder.

[0053] Configuration of the extruder: The screw length-diameter ratio is 55, the screw speed is 500 r / min, the extrusion temperature is set to 190 - 230 °C, and there are 8 heating zones in total.

[0054] During the extrusion process, apply a high-frequency pulsed electric field with an electric field strength of 1 - 3 kV / cm and a frequency of 10 - 30 kHz to promote the formation of an orderly oriented microstructure of talcum powder lamellae and polymer microspheres in the PP matrix.

[0055] Finally, carry out cooling and pelletizing.

[0056] Table 1 Raw material information table of examples and comparative examples

[0057]

[0058]

[0059] Note: 1. Test conditions for the melt flow rate of PP: 230°C, 2.16 kg

[0060] 2. Test conditions for the melt flow rate of POE: 190°C, 2.16 kg

[0061] The above raw materials and reagents are only examples of some specific embodiments of the present invention to make the technical solutions of the present invention clearer, and do not represent that the present invention can only use the above reagents. The specific scope is subject to the claims. In addition, the "parts" mentioned in the examples and comparative examples refer to parts by weight unless otherwise specified.

[0062] Comparative Example 1: Traditional polypropylene without any pretreatment was used as the matrix material, and only 10 parts of ordinary talcum powder (without crystal form regulation treatment) and 5 parts of conventional toughening agent (non-core-shell structure polymer microspheres) were added. Graphene, compatibilizer, nucleating agent, antioxidant and ultraviolet light absorber were not added. It was prepared according to the conventional single-screw extruder processing technology, with an extrusion temperature of 180 - 210°C and a screw speed of 300 r / min.

[0063] Comparative Example 2: Polypropylene pretreated by plasma (treatment time 5 minutes, power 100 W) was used as the matrix, 10 parts of ordinary talcum powder (without crystal form regulation treatment) and 5 parts of core-shell structure polymer microspheres were added as the toughening agent, and 1 part of compatibilizer (non-SEBS). Graphene, nucleating agent, antioxidant and ultraviolet light absorber were not added. A twin-screw extruder was used with a screw length-to-diameter ratio of 40, a rotation speed of 400 r / min, and an extrusion temperature of 190 - 220°C, without high-frequency pulsed electric field treatment.

[0064] Comparative Example 3: Polypropylene pretreated by plasma (treatment time 15 minutes, power 300 W) was selected, 10 parts of talcum powder with crystal form regulation (treated according to the method in the invention), 5 parts of core-shell structure polymer microsphere toughening agent, and 1 part of SEBS compatibilizer were added. Graphene, nucleating agent, antioxidant and ultraviolet light absorber were not added. A twin-screw extruder was used with a screw length-to-diameter ratio of 50, a rotation speed of 500 r / min, and an extrusion temperature of 190 - 230°C, but no high-frequency pulsed electric field was applied.

[0065] Example 1: According to the formula in the invention content, 50 parts of polypropylene pretreated by plasma (treatment time 10 minutes, power 200W), 15 parts of toughening agent (polymer microspheres with core-shell structure), 5 parts of talc powder after crystal form regulation, 3 parts of SEBS compatibilizer, 3 parts of graphene after ultrasonic pretreatment, 1.5 parts of zinc stearate nucleating agent, 0.5 parts of antioxidant (a mixture of 1076 and 168 in a ratio of 1:1), and 1 part of ultraviolet absorber (a composite of ultraviolet absorber and light stabilizer) are used. According to the preparation method in the invention, the ratio of the screw length to the diameter of the twin-screw extruder is 55, the rotation speed is 500 r / min, the extrusion temperature is 190 - 230 °C (8 heating zones show a gradient change), and a high-frequency pulsed electric field with an electric field intensity of 2 kV / cm and a frequency of 20 kHz is applied during the extrusion process.

[0066] Example 2: 65 parts of polypropylene pretreated by plasma (treatment time 8 minutes, power 150W), 10 parts of toughening agent (polymer microspheres with core-shell structure), 10 parts of talc powder after crystal form regulation, 2 parts of SEBS compatibilizer, 2 parts of graphene after ultrasonic pretreatment, 1 part of zinc stearate nucleating agent, 0.3 parts of antioxidant (a mixture of 1076 and 168 in a ratio of 1:1), and 0.5 parts of ultraviolet absorber (a composite of ultraviolet absorber and light stabilizer) are selected. The preparation method is the same as that of Example 1.

[0067] Example 3: 80 parts of polypropylene pretreated by plasma (treatment time 12 minutes, power 250W), 5 parts of toughening agent (polymer microspheres with core-shell structure), 20 parts of talc powder after crystal form regulation, 1 part of SEBS compatibilizer, 1 part of graphene after ultrasonic pretreatment, 0.5 parts of zinc stearate nucleating agent, 0.1 parts of antioxidant (a mixture of 1076 and 168 in a ratio of 1:1), and 0.1 parts of ultraviolet absorber (a composite of ultraviolet absorber and light stabilizer) are used. The preparation method is the same as that of Example 1.

[0068] Performance Test

[0069] The materials prepared in each comparative example and example are subjected to performance tests. The test items and standards are as follows:

[0070] 1. Density (ρ): Tested according to GB / T 1033.1, Method A.

[0071] 2. Melt flow rate (MFR): Tested according to GB / T 3682, Method A, under the conditions of 230 °C and a load of 2.16 Kg.

[0072] 3. Tensile strength (TS): Tested according to GB / T 1040.1 and GB / T 1040.2, using 1A type injection molded specimens, with an experimental speed of 50 mm / min.

[0073] 4. Tensile strength after heat aging: After heat aging the test specimens at 150 °C for 700 h, test them according to GB / T 1040.1 and GB / T 1040.2. For 1A type injection-molded test specimens, the test speed is 50 mm / min.

[0074] 5. Flexural modulus (FM): According to GB / T 9341, test specimens with dimensions of 80 mm × 10 mm × (4.0 ± 0.2) mm, test speed of 2 mm / min, and support span of 64 mm are tested.

[0075] 6. Notched impact strength (IZOD): According to GB / T 1843, test specimens with dimensions of 80 mm × 10 mm × (4.0 ± 0.2) mm and A-type notches (finished by machining) are tested.

[0076] 7. Notched impact strength after heat aging resistance: After heat aging treatment of the test specimens at 150 °C for 700 h, according to GB / T 1843, test specimens with dimensions of 80 mm × 10 mm × (4.0 ± 0.2) mm and A-type notches are tested.

[0077] 8. Yellowness index (YI): Total irradiation dose is 488 kJ / m 2 , test according to HG / T 3862-2006.

[0078] 9. Cross scratch (ΔL): With a load of 10 N, a scraper head diameter of 1 mm, a speed of 1000 mm / min, a line distance of 2 mm, and a scratch length ≥ 40 mm for testing.

[0079] Prepare test specimens and color plates from the modified polypropylene materials obtained in the above examples through an injection molding machine, test the performance according to the above conditions, and record the results in the following table.

[0080] Table 2 Test Results

[0081]

[0082]

[0083] Conclusion

[0084] 1. Compared with Comparative Example 1: In the examples, through plasma pretreatment of polypropylene, using talc powder after crystal form regulation, adding graphene, compatibilizer, nucleating agent, antioxidant, and ultraviolet light absorber, and adopting a special preparation process, the tensile strength, flexural modulus, notched impact strength, and heat aging resistance of the material are significantly improved, the density and yellowness index of the material are reduced, and the surface hardness and wear resistance of the material are improved, which proves the effectiveness of the synergistic effect of the pretreatment methods of each raw material, formula optimization, and preparation process in the present invention on the improvement of material properties.

[0085] 2. Compared with Comparative Example 2: Although polypropylene was pretreated and some improved raw materials were used in Comparative Example 2, key components such as graphene and suitable nucleating agents were not added, and the improvement of material properties was limited. Through the complete formulation design, the Examples showed better performance in terms of melt flow rate, tensile strength, impact strength, heat aging resistance, etc., indicating that components such as graphene and nucleating agents play an important role in improving the comprehensive properties of the material.

[0086] 3. Compared with Comparative Example 3: Comparative Example 3 lacked high-frequency pulsed electric field treatment. After applying high-frequency pulsed electric field in the Examples, various properties of the material such as tensile strength, flexural modulus, notched impact strength, and heat aging resistance were further improved, indicating that high-frequency pulsed electric field treatment helps to promote the orderly orientation of fillers and polymer microspheres in the matrix, optimize the microstructure of the material, and thus improve the material properties.

[0087] 4. Comparison between the Examples: As the content of polypropylene increases, the density of the material slightly increases, the tensile strength and flexural modulus increase to a certain extent, but the notched impact strength decreases; increasing the content of talc powder will improve the rigidity (increase in flexural modulus) and density of the material; the reasonable combination of components such as graphene and toughening agents plays a key role in balancing the comprehensive properties of the material. In practical applications, the proportion of each component can be adjusted according to the specific performance requirements of automotive parts to achieve the best performance effect.

Claims

1. A talc-filled modified polypropylene material, characterized in that: It includes the following raw materials in parts by weight:

2. The talc-filled modified polypropylene material according to claim 1, characterized in that: The polypropylene is polypropylene pretreated by plasma, the treatment time is 5-15 minutes, the power is 100-300W; the weight average molecular weight (Mw) of the polypropylene is between 200,000 and 500,000, and the molecular weight distribution index (Mw / Mn) is 2.5-4.

0.

3. The talc-filled modified polypropylene material according to claim 1, characterized in that: The graphene is graphene pretreated by ultrasound.

4. The talc-filled modified polypropylene material according to claim 1, characterized in that: The talcum powder is a special talcum powder with a lamellar structure, which is first dispersed in a solution containing a coupling agent by ultrasonic wave, with an ultrasonic power of 200-400W and a time of 10-20 minutes. The coupling agent is a silane coupling agent. Subsequently, a crystal form regulation treatment is performed under high temperature and high pressure, with a temperature of 300-400°C, a pressure of 5-10MPa, and a treatment time of 30-60 minutes.

5. The talc-filled modified polypropylene material according to claim 1, characterized in that: The compatibilizer is SEBS.

6. The talc-filled modified polypropylene material according to claim 1, characterized in that: The toughening agent is a polymer microsphere with a core-shell structure, wherein the inner core is polybutadiene rubber and the outer core is a polypropylene graft copolymer having good compatibility with PP, and the microsphere is prepared by an emulsion polymerization method.

7. The talc-filled modified polypropylene material according to claim 1, characterized in that: The nucleating agent is zinc stearate nucleating agent.

8. The talc-filled modified polypropylene material according to claim 1, characterized in that: The invention also comprises 0.1 to 0.5 parts by weight of an antioxidant and 0.1 to 1 parts by weight of an anti-ultraviolet agent.

9. The talc-filled modified polypropylene material according to claim 8, characterized in that: The anti-ultraviolet agent is a compound of an ultraviolet absorber and a light stabilizer; the antioxidant is a composite antioxidant, which is a combination of 1076 and 168.

10. A method for preparing a talc-filled modified polypropylene material, characterized in that: The following steps are involved: 1) Pre-treating graphene by ultrasonic wave; 2) Premix the pretreated polypropylene resin, the talc powder after crystal form adjustment, and the ultrasonically treated graphene under high-speed stirring at a speed of 1500-2500 r / min for 10-15 minutes to preliminarily build a foundation for combining the two; 3) Add core-shell polymer microspheres, antioxidant, light stabilizer and nucleating agent to the side feed port of the twin-screw extruder, and add the premix of polypropylene resin and talcum powder from the main feed port; 4) The twin-screw extruder uses a special combined screw, which contains multiple kneading blocks and reverse screw elements, with a screw length-to-diameter ratio of 50-60; the screw speed is 400-600r / min, the extrusion temperature is set at 190-230℃, and it is divided into 8 heating zones, with the temperature of each zone changing in a gradient to achieve sufficient mixing and reaction; 5) During the extrusion process, a high-frequency pulse electric field is applied with an electric field strength of 1-3 kV / cm and a frequency of 10-30 kHz to promote the formation of an orderly oriented microstructure of talc flakes and polymer microspheres in the PP matrix; 6) After water cooling, drawing and pelletizing, the target material is obtained.

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