A waste tire rubber powder toughened recycled polypropylene material and a preparation method thereof

Abstract

This invention relates to the field of polymer composite materials, specifically disclosing a recycled polypropylene material toughened with waste tire rubber powder and its preparation method. The material is prepared from waste tire rubber powder, recycled polypropylene, and an interface compatibilizer. The waste tire rubber powder undergoes surface activation modification treatment, introducing active functional groups onto the powder surface to form a chemically bonded interface with the recycled polypropylene. The preparation method includes: surface-activating and modifying the waste tire rubber powder to obtain modified rubber powder; mixing the modified rubber powder with recycled polypropylene and an interface compatibilizer; and then melt-blending, extruding, and granulating to obtain composite wires. This invention, through surface activation modification, constructs a chemically bonded interface between the rubber powder and polypropylene, significantly improving their compatibility and achieving efficient toughening of recycled polypropylene. It also endows the material with good 3D printing adaptability and damping properties, making it suitable for industrial cushioning components, sports protective gear, and other fields.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite materials, specifically a toughened recycled polypropylene material made from waste tire rubber powder and its preparation method. Background Technology

[0002] Polypropylene (PP) is one of the five major general-purpose plastics, possessing advantages such as low density, chemical resistance, and ease of processing, and is widely used in automobiles, home appliances, packaging, and other fields. With the continuous growth in the consumption of plastic products, the generation of recycled polypropylene (rPP) has also increased year by year. Reprocessing and reusing recycled polypropylene can reduce the consumption of fossil resources and alleviate the environmental pressure caused by plastic waste. However, the molecular chains of recycled polypropylene degrade during multiple processing heat histories, leading to a significant decrease in its toughness and often lower impact resistance than virgin polypropylene. This limits its reuse in engineering or consumer products that require a certain level of toughness.

[0003] On the other hand, waste tires are a significant source of solid waste, and their rubber components have a cross-linked network structure, making them difficult to degrade naturally. Processing waste tires into rubber powder (GTR) and utilizing it for resource recovery is currently recognized as an effective approach. Rubber itself has high elasticity, and if it can be used as a toughening agent to fill recycled polypropylene, theoretically, a synergistic effect of "treating waste with waste" can be achieved. However, the main component of waste tire rubber powder is vulcanized rubber, which has low surface energy and weak polarity, while recycled polypropylene is a non-polar crystalline polymer, making the two thermodynamically incompatible. During simple melt blending, an effective interfacial bond cannot be formed between the rubber powder and the polypropylene matrix, and the rubber powder particles are prone to agglomeration. Under external force, cracks in the composite material preferentially propagate along the rubber powder-matrix interface, resulting in lower tensile strength and impact toughness compared to the pure polypropylene matrix. While existing technologies have reported modifications using coupling agents or grafts, most only involve adding compatibilizers during the blending stage. The surface of the rubber powder is not pre-activated or modified, making it impossible to form a strong chemical bond interface with the polypropylene matrix. This results in limited toughening effects and fails to meet the requirements of high-precision fused deposition modeling (FDM) 3D printing for filament mechanical properties and printing stability. Therefore, establishing a stable chemical bond interface between waste tire rubber powder and recycled polypropylene is crucial for achieving efficient toughening while maintaining 3D printing adaptability. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a recycled polypropylene material toughened with waste tire rubber powder and its preparation method, thereby solving the problem in the prior art where waste tire rubber powder and recycled polypropylene cannot form a chemical bonding interface due to interfacial incompatibility, resulting in poor toughening effect of the composite material.

[0005] This invention provides a recycled polypropylene material toughened with waste tire rubber powder, the material being prepared from the following raw materials:

[0006] Waste tire rubber powder, recycled polypropylene, and interface compatibilizers;

[0007] The waste tire rubber powder undergoes surface activation modification treatment, introducing active functional groups on the surface of the rubber powder to form a chemical bonding interface with recycled polypropylene.

[0008] Preferably, the particle size of the waste tire rubber powder is one or more combinations of 40 mesh, 60 mesh or 80 mesh, and the addition mass ratio is 20% to 40%.

[0009] Preferably, the interface compatibilizer is at least one of a silane coupling agent or a maleic anhydride graft copolymer.

[0010] Preferably, the silane coupling agent is KH550 or KH570; the maleic anhydride graft copolymer is POE-g-MAH or PP-g-MAH.

[0011] Preferably, the surface activation modification treatment of the waste tire rubber powder includes:

[0012] Under the conditions of reaction temperature of 80℃~120℃ and reaction time of 30min~90min, functional group grafting modification of the surface of the adhesive powder is carried out by using silane coupling agent or maleic anhydride graft copolymer.

[0013] This invention also provides a method for preparing recycled polypropylene material toughened with the above-mentioned waste tire rubber powder, comprising the following steps:

[0014] (1) Surface activation modification treatment is carried out on waste tire rubber powder to obtain modified rubber powder;

[0015] (2) The modified rubber powder is mixed with recycled polypropylene and interface compatibilizer in a certain proportion to obtain a mixture;

[0016] (3) The mixture is melt-blended and extruded to granulate to obtain composite wire.

[0017] Preferably, the surface activation modification treatment in step (1) is as follows:

[0018] Chemical grafting of the adhesive powder with silane coupling agents or maleic anhydride graft copolymers introduces active functional groups.

[0019] Preferably, the temperature of melt blending in step (3) is 180℃~220℃ and the extrusion speed is 30~60r / min.

[0020] Preferably, the diameter of the composite wire is 1.75mm or 2.85mm, and the diameter tolerance is ≤ ±0.05mm.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] By surface activation modification of waste tire rubber powder, active functional groups are successfully introduced into the surface of the rubber powder, enabling it to form a stable chemical bonding interface with recycled polypropylene, which significantly improves the compatibility between the two. Compared with direct blending of unmodified rubber powder, this invention effectively solves the technical problem of weak interfacial bonding and low stress transfer efficiency caused by the large polarity difference between rubber powder and polypropylene.

[0023] By constructing chemically bonded interfaces, this invention achieves highly efficient toughening of recycled polypropylene using waste tire rubber powder. The modified rubber powder, as a dispersed phase, is uniformly distributed within the polypropylene matrix. Upon impact, it effectively induces crazes and shear bands, absorbing a large amount of impact energy, thereby significantly improving the impact resistance of the composite material. Simultaneously, the excellent interfacial bonding ensures that the tensile strength is not excessively degraded by the introduction of the rubber powder, achieving a balance between stiffness and toughness.

[0024] The composite filament provided by this invention exhibits excellent 3D printing adaptability, a continuous and stable printing process, high filament diameter accuracy, and good interlayer bonding and smooth surface of the printed parts. The resulting products demonstrate excellent damping and vibration reduction performance near room temperature, effectively absorbing and dissipating vibration energy. This invention utilizes two waste resources—waste tires and recycled polypropylene—as raw materials, achieving high-value reuse of waste, reducing material costs, and demonstrating significant economic and environmental benefits, thus aligning with the development requirements of green manufacturing and a circular economy. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the preparation method of Embodiment 1 of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] The present invention will be further illustrated by specific embodiments below, but the scope of protection of the present invention is not limited thereto.

[0028] Raw materials and testing methods:

[0029] The recycled polypropylene (rPP) used in all examples and comparative examples was from the same batch, with a melt flow index of 8 ± 0.5 g / 10 min (230 °C, 2.16 kg, ASTM D1238); the waste tire rubber powder (GTR) was provided by an environmental technology company and was vacuum dried at 80 °C for 4 hours before use; the silane coupling agents KH550 and KH570 were purchased from Nanjing Shuguang Chemical Group, and the maleic anhydride graft copolymers PP-g-MAH (grafting rate 1.2%) and POE-g-MAH (grafting rate 1.0%) were purchased from Ningbo Nengzhiguang New Material Technology Co., Ltd.

[0030] Mechanical property testing methods:

[0031] Tensile strength: Tested according to ASTM D638 standard using an Instron 5966 universal testing machine, dumbbell-shaped specimens, tensile rate 50 mm / min, 5 specimens per group, average value ± standard deviation.

[0032] Notched impact strength: Tested according to ASTM D256 standard using a Zwick HIT25P pendulum impact tester, type A notch, 5 specimens per group, average value ± standard deviation.

[0033] Printing performance evaluation: Using an FDM 3D printer (nozzle temperature 220℃, platform temperature 60℃, printing speed 50mm / s), continuous printing was conducted to observe line breakage and surface quality.

[0034] Example 1: Preparation method, such as Figure 1 As shown;

[0035] (1) Raw material ratio: Waste tire rubber powder (40 mesh) is added at a mass ratio of 30%, recycled polypropylene is added at a mass ratio of 70%, and the interface compatibilizer is KH550 (the amount is 2% of the mass of rubber powder).

[0036] (2) Surface activation modification treatment: waste tire rubber powder and KH550 are mixed evenly in a high-speed mixer, transferred to a reaction vessel, and reacted at 100℃ for 60 min to obtain modified rubber powder with surface grafted amino functional groups.

[0037] (3) Mixing: Add the modified rubber powder, recycled polypropylene and the remaining interface compatibilizer into a high-speed mixer in the above proportions, and mix at room temperature for 10 minutes to obtain the mixture.

[0038] (4) Melt blending and extrusion granulation: The mixture is added to a twin-screw extruder, the melt blending temperature is set to 200℃ and the extrusion speed is 45r / min. After melting, shearing and mixing, the mixture is extruded and granulated, and then extruded and formed by a single-screw wire extruder to obtain a composite wire with a diameter of 1.75mm and a diameter tolerance of ±0.03mm.

[0039] (5) Performance test: The results are shown in Table 2.

[0040] Example 2: The difference from Example 1 is as follows:

[0041] The waste tire rubber powder has a particle size of 60 mesh and is added at a ratio of 20%.

[0042] The interface compatibilizer is PP-g-MAH, and its dosage is 3% of the mass of the adhesive powder.

[0043] The surface modification treatment temperature was 80℃ and the time was 90 min;

[0044] The melt blending temperature is 180℃, and the extrusion speed is 30 r / min;

[0045] The wire diameter is 2.85mm, with a tolerance of ±0.04mm.

[0046] The performance test results are shown in Table 2.

[0047] Example 3: The difference from Example 1 is as follows:

[0048] The waste tire rubber powder has a particle size of 80 mesh and is added at a ratio of 40%.

[0049] The interface compatibilizer is KH570, and the dosage is 2.5% of the mass of the adhesive powder.

[0050] The surface modification treatment temperature was 120℃ and the time was 30 min;

[0051] The melt blending temperature is 220℃ and the extrusion speed is 60 r / min.

[0052] The performance test results are shown in Table 2.

[0053] Example 4: The difference from Example 1 is as follows:

[0054] The interface compatibilizer is a compound of POE-g-MAH (3% of the mass of the adhesive powder) and KH550 (1% of the mass of the adhesive powder).

[0055] The surface modification treatment temperature was 110℃ and the time was 50 min.

[0056] The performance test results are shown in Table 2.

[0057] Comparative Example 1: The difference from Example 1 is that:

[0058] Waste tire rubber powder was not subjected to surface activation modification treatment and was directly blended with recycled polypropylene and KH550. The performance test results are shown in Table 2.

[0059] Comparative Example 2: The difference from Example 1 is that:

[0060] No interface compatibilizers are added, and the adhesive powder is not modified.

[0061] The performance test results are shown in Table 2.

[0062] Comparative Example 3: The difference from Example 1 is that:

[0063] The proportion of adhesive powder added was 50%; although it underwent the same modification treatment, the filaments broke and the surface became rough during the extrusion process, making it impossible to stably prepare 3D printing filaments.

[0064] The performance test results are shown in Table 2.

[0065] Summary of process parameters and performance of the examples and comparative examples

[0066] Table 1 Raw material ratios and process parameters for each embodiment

[0067] parameter Example 1 Example 2 Example 3 Example 4 GTR particle size (mesh) 40 60 80 40 GTR addition percentage (%) 30 20 40 30 Interface compatibilizer KH550 (2%) PP-g-MAH (3%) KH570 (2.5%) POE-g-MAH(3%)+KH550(1%) Modification temperature (°C) 100 80 120 110 Modification time (min) 60 90 30 50 Melting temperature (°C) 200 180 220 200 Extrusion speed (r / min) 45 30 60 45 Wire diameter (mm) 1.75 2.85 1.75 1.75

[0068] Table 2 Performance test results of each embodiment and comparative example

[0069] Sample number Tensile strength (MPa) Notched impact strength (kJ / m²) Printing performance Example 1 24.5±1.1 12.8±0.8 No disconnection for ≥8 hours Example 2 26.8±1.3 10.5±0.7 No disconnection for ≥8 hours Example 3 21.2±0.9 14.3±1.0 No disconnection for ≥8 hours Example 4 25.1±1.2 13.6±0.9 No disconnection for ≥8 hours Comparative Example 1 18.3±1.0 6.2±0.6 Occasional line breakage after 2 hours of printing Comparative Example 2 15.6±0.8 4.5±0.5 Frequent line drops within 1 hour of printing Comparative Example 3 17.5±1.4 9.8±0.9 Unable to print stably

[0070] Results Analysis: As can be seen from Tables 1 and 2:

[0071] 1. Interface modification effects

[0072] Comparative Example 1 and Comparative Example 1: After surface activation modification treatment, the tensile strength increased from 18.3 MPa to 24.5 MPa (an increase of 33.9%), and the notched impact strength increased from 6.2 kJ / m² to 12.8 kJ / m² (an increase of 106.5%). This indicates that introducing active functional groups on the surface of the adhesive powder to form a chemical bonding interface significantly improves the compatibility between GTR and rPP.

[0073] 2. Necessity of compatibilizers

[0074] Comparative Example 2, without any added interface compatibilizer and without modification, had an impact strength of only 4.5 kJ / m² and a tensile strength of only 15.6 MPa, both of which failed to meet the requirements for industrial applications, proving that the presence of an interface compatibilizer is a necessary condition for achieving the toughening effect.

[0075] 3. The effect of GTR addition ratio

[0076] Example 1 (30% added): Tensile strength 24.5MPa, impact strength 12.8kJ / m², with balanced overall performance;

[0077] Example 3 (40% addition): Impact strength increased to 14.3 kJ / m² (11.7% higher than Example 1), but tensile strength decreased to 21.2 MPa;

[0078] Comparative Example 3 (50% addition): The processing performance deteriorated sharply, and it was impossible to stably prepare 3D printing filaments, proving that the addition range of 20% to 40% has critical significance.

[0079] 4. Influence of GTR particle size

[0080] Example 2 (60 mesh, 20% additive): highest tensile strength (26.8 MPa), but relatively low impact strength (10.5 kJ / m²).

[0081] Example 3 (80 mesh, 40% additive): highest impact strength (14.3kJ / m²), suitable for high toughness requirements;

[0082] Example 1 (40 mesh, 30% additive): Overall performance is balanced, making it the preferred solution.

[0083] 5. Effect of compound compatibilizer

[0084] Example 4 uses a compound of POE-g-MAH and KH550, and its overall performance is better than that of Example 1 with a single compatibilizer: tensile strength is 25.1 MPa (increased by 2.4%) and impact strength is 13.6 kJ / m² (increased by 6.3%), proving that the compound scheme can achieve a better toughening effect.

[0085] 6. Printability

[0086] The filaments used in Examples 1-4 all met the requirement of continuous printing for more than 8 hours without breakage, and the printed parts had smooth surfaces and good interlayer bonding. Each comparative example showed printing defects of varying degrees, proving that the material of the present invention has good adaptability to 3D printing processes.

[0087] Dynamic mechanical property analysis (DMA): To further characterize the damping and vibration reduction performance of the material, the composite wire from Example 1 was tested using a TA Instruments Q800 dynamic mechanical analyzer. The test mode was a double cantilever beam, with a frequency of 1 Hz, a heating rate of 3℃ / min, and a temperature range of -80℃ to 80℃. Comparative Examples 1 and 2 were tested simultaneously as controls; three samples were tested in each group, and the average value was taken.

[0088] Table 3 Dynamic mechanical performance test results

[0089] Sample number tanδ peak temperature (°C) tanδ peak height Example 1 -35±2 0.42±0.03 Comparative Example 1 -38±2 0.28±0.02 Comparative Example 2 -40±2 0.21±0.02

[0090] The results show that the peak tanδ height of Example 1 is 50% higher than that of Comparative Example 1 and 100% higher than that of Comparative Example 2. At room temperature (-35℃ to 25℃), the tanδ value of Example 1 is greater than 0.3, indicating that the material of this invention has excellent damping and shock absorption performance and is suitable for applications requiring the absorption of impact energy, such as sports protective gear and industrial cushioning pads.

[0091] The embodiments of the present invention are given for the purposes of illustration and description. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made by those skilled in the art to the above embodiments within the scope of the present invention should be included within the protection scope of the present invention.

Claims

1. A toughened recycled polypropylene material made from waste tire rubber powder, characterized in that, The material is prepared from the following raw materials: Waste tire rubber powder, recycled polypropylene, and interface compatibilizers; The waste tire rubber powder undergoes surface activation modification treatment, introducing active functional groups on the surface of the rubber powder to form a chemical bonding interface with recycled polypropylene.

2. The recycled polypropylene material toughened with waste tire rubber powder according to claim 1, characterized in that, The waste tire rubber powder has a particle size of one or more combinations of 40 mesh, 60 mesh or 80 mesh, and is added in a mass ratio of 20% to 40%.

3. The recycled polypropylene material toughened with waste tire rubber powder according to claim 1, characterized in that, The interface compatibilizer is at least one of a silane coupling agent or a maleic anhydride graft copolymer.

4. The recycled polypropylene material toughened with waste tire rubber powder according to claim 3, characterized in that, The silane coupling agent is KH550 or KH570; the maleic anhydride graft copolymer is POE-g-MAH or PP-g-MAH.

5. The recycled polypropylene material toughened with waste tire rubber powder according to claim 1, characterized in that, The surface activation modification treatment of the waste tire rubber powder includes: Under the conditions of reaction temperature of 80℃~120℃ and reaction time of 30min~90min, functional group grafting modification of the surface of the adhesive powder is carried out by using silane coupling agent or maleic anhydride graft copolymer.

6. A method for preparing a toughened recycled polypropylene material made from waste tire rubber powder according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Surface activation modification treatment is carried out on waste tire rubber powder to obtain modified rubber powder; (2) The modified rubber powder is mixed with recycled polypropylene and interface compatibilizer in a certain proportion to obtain a mixture; (3) The mixture is melt-blended and extruded to granulate to obtain composite wire.

7. The preparation method according to claim 6, characterized in that, The surface activation modification treatment mentioned in step (1) is as follows: Chemical grafting of the adhesive powder with silane coupling agents or maleic anhydride graft copolymers introduces active functional groups.

8. The preparation method according to claim 6, characterized in that, The temperature of melt blending in step (3) is 180℃~220℃, and the extrusion speed is 30~60r / min.

9. The preparation method according to claim 6, characterized in that, The diameter of the composite wire is 1.75mm or 2.85mm, with a diameter tolerance of ≤±0.05mm.

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