Polypropylene material as well as preparation method and application thereof

Abstract

The invention discloses a polypropylene material as well as a preparation method and application thereof. The polypropylene material comprises the following components in parts by weight: 45-65 parts of maleic anhydride grafted polypropylene, 25-45 parts of glutamic acid and metal salt and 10-25 parts of a thermoplastic elastomer. The weight ratio of the glutamic acid to the metal salt is 1: (0.3-1.8). The polypropylene material disclosed by the invention has good self-healing performance and also has good flexibility.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more specifically, to a polypropylene material, its preparation method, and its applications. Background Technology

[0002] As automotive interiors evolve towards "high durability, intelligence, and environmental friendliness," traditional automotive polypropylene materials have relatively low hardness in high-frequency contact areas such as door panels and center consoles. This makes them easily scratched by metal objects (such as keys and zippers), leading to surface whitening and reduced gloss, severely impacting the interior's aesthetics. Luxury models and new energy vehicles have even higher requirements for interior quality, demanding a smooth feel and durability.

[0003] When pure PP is used for injection molding automotive door panels, center consoles, and other interior parts, the melt is prone to tensile fracture and cannot fill the mold details well. However, maleic anhydride grafted polypropylene (MAH-g-PP) has a slightly higher melt strength than pure PP, so its melt is less prone to tensile fracture and can fill the mold details well, reducing shrinkage marks and warping deformation of the product. This improves the appearance flatness and dimensional accuracy of automotive interior parts. Therefore, MAH-g-PP is often used to replace pure PP in the preparation of automotive interior parts.

[0004] Currently, maleic anhydride-grafted polypropylene (MAH-g-PP) and elastomers are commonly used materials for preparing automotive interior parts. However, their self-healing properties are poor, making it difficult for automotive interior parts made from them to self-repair scratches caused by metal objects (such as keys, zippers, etc.).

[0005] Therefore, developing a polypropylene material with strong self-healing properties is of great significance. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a polypropylene material, its preparation method, and its application.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a polypropylene material comprising the following components in parts by weight: 45-65 parts maleic anhydride-grafted polypropylene (MAH-g-PP), 25-45 parts glutamic acid and metal salt, 10-25 parts thermoplastic elastomer; The weight ratio of the glutamic acid to the metal salt is 1:(0.3-1.8).

[0008] In the maleic anhydride-grafted polypropylene (MAH-g-PP) and thermoplastic elastomer system of this invention, on the one hand, by using a specific weight ratio of glutamic acid and metal salt to regulate the number of reversible dynamic bonds, namely the number of hydrogen bonds formed between carboxyl groups and the number of coordination bonds formed between metal ions and carboxyl groups, the polypropylene material can achieve reversible breakage and reconstruction of reversible dynamic bonds under thermal action, thereby improving the self-healing performance of the polypropylene material; on the other hand, the interaction of hydrogen bonds, coordination bonds and covalent bonds forms a hybrid cross-linked network structure, which strengthens the reversible breakage and reconstruction of reversible dynamic bonds, thereby improving the self-healing performance of the polypropylene material.

[0009] Preferably, the weight ratio of the glutamic acid to the metal salt is one or any two of the following: 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, and 1:1.8.

[0010] More preferably, the weight ratio of the glutamic acid to the metal salt is 1:(0.5-1.5).

[0011] Preferably, the metal salt is at least one selected from iron salt, calcium salt, magnesium salt, copper salt, manganese salt, cobalt salt, nickel salt, zinc salt, and aluminum salt.

[0012] In this invention, metal salts include salts of metals in different valence states, for example, the iron salts include at least one of divalent iron salts and trivalent iron salts.

[0013] Preferably, the anion of the metal salt is at least one selected from chloride, nitrate, carbonate, and sulfate.

[0014] Preferably, the metal salt includes at least one of ferric chloride, ferric nitrate, ferric sulfate, ferrous chloride, calcium chloride, zinc chloride, and aluminum chloride.

[0015] Preferably, the maleic anhydride grafting rate in the maleic anhydride-grafted polypropylene (MAH-g-PP) is 0.1-1.8 wt%, specifically 0.3-1.5 wt%.

[0016] Preferably, the maleic anhydride grafting rate in the maleic anhydride-grafted polypropylene (MAH-g-PP) is within the range of one or any two of the following: 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1.0wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, and 1.8wt%.

[0017] More preferably, the maleic anhydride grafting rate in the maleic anhydride-grafted polypropylene (MAH-g-PP) is 0.6-1.2 wt%.

[0018] In this invention, the method for testing the maleic anhydride grafting rate in maleic anhydride-grafted polypropylene (MAH-g-PP) is acid-base titration, specifically: (1) Sample purification: Accurately weigh about 1-2 grams (denoted as m0, accurate to 0.0001 g) of MAH-g-PP powder or granules, place them in a Soxhlet extractor, and continuously extract with solvents such as acetone or xylene for 8-24 h to completely remove unreacted free maleic anhydride monomers and their oligomers; then place the purified sample in an 80℃ vacuum oven and dry to constant weight (denoted as m1, unit g); (2) Hydrolysis and saponification: Place the dried purified sample in a 250 mL Erlenmeyer flask, add 100 mL of excess xylene solution of known concentration (e.g., 0.05 mol / L, solvent is water), and heat under nitrogen protection and reflux (about 140 °C) to completely dissolve the sample; then, accurately add 25 mL of potassium hydroxide-ethanol standard solution of known concentration (e.g., 0.1 mol / L) with a pipette, and continue to reflux for more than 2 hours to ensure that the grafted maleic anhydride groups are completely hydrolyzed and generate potassium maleate salt; (3) Back titration: Cool the solution to room temperature, add 2-3 drops of phenolphthalein indicator; use a known concentration C HCl standard hydrochloric acid solutions (e.g., C) HCl Titrate with 0.1 mol / L hydrochloric acid standard solution until the pink color of the solution just disappears, and record the volume of hydrochloric acid standard solution consumed (V1, unit L). (4) Blank experiment: Without adding MAH-g-PP sample, repeat steps 2 and 3 above and record the volume of hydrochloric acid standard solution consumed in the blank experiment (V0, unit L). The maleic anhydride grafting rate (GR) in MAH-g-PP is calculated using the following formula: GR(wt%) = (V0-V1)×C HCl ×M MAH / (2×m1)×100%, where M MAH is the molecular weight of maleic anhydride.

[0019] Preferably, the polypropylene material further includes 0-3 parts of antioxidant.

[0020] More preferably, the antioxidant is expressed in parts by weight of one or any two of the following: 0 parts, 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, 2 parts, 2.1 parts, 2.2 parts, 2.3 parts, 2.4 parts, 2.5 parts, 2.6 parts, 2.7 parts, 2.8 parts, 2.9 parts, and 3 parts.

[0021] More preferably, the antioxidant is present in 0.2-2 parts by weight.

[0022] More preferably, the antioxidant includes at least one of hindered phenolic antioxidants and phosphite antioxidants.

[0023] More preferably, the hindered phenolic antioxidant includes at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076), and N,N'-(hexane-1,6-diyl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide] (antioxidant 1098).

[0024] More preferably, the phosphite antioxidant includes at least one of tris(2,4-di-tert-butyl)phosphite (antioxidant 168), bis(2,4-di-tert-butylphenol) pentaerythritol diphosphite (antioxidant 626), and triphenyl phosphite (antioxidant TPP).

[0025] More preferably, the weight ratio of the hindered phenolic antioxidant to the phosphite antioxidant is (0-1.5):(0-1.5), specifically (0.1-1):(0.1-1).

[0026] Preferably, the thermoplastic elastomer includes at least one of POE (polyolefin elastomer), SBS (styrene-butadiene-styrene block copolymer), and SEBS (styrene-ethylene / butene-styrene block copolymer).

[0027] Preferably, in the polypropylene material, the weight parts of maleic anhydride-grafted polypropylene are 45 parts, 47 parts, 50 parts, 52 parts, 55 parts, 57 parts, 60 parts, 62 parts, and 65 parts, or any two of these values; the total weight parts of glutamic acid and metal salt are 25 parts, 27 parts, 30 parts, 32 parts, 35 parts, 37 parts, 40 parts, 42 parts, and 45 parts, or any two of these values; and the weight parts of thermoplastic elastomer are 10 parts, 12 parts, 15 parts, 17 parts, 20 parts, 22 parts, and 25 parts, or any two of these values.

[0028] Preferably, the polypropylene material comprises the following components in parts by weight: 50-60 parts maleic anhydride-grafted polypropylene, 30-40 parts glutamic acid and metal salt, 15-20 parts thermoplastic elastomer.

[0029] Preferably, based on the weight of the polypropylene material, the weight percentage of the maleic anhydride-grafted polypropylene is ≥40%, specifically 45%-55%.

[0030] Secondly, the present invention provides a method for preparing a polypropylene material, comprising the following steps: Mix the components, melt and extrude to obtain polypropylene material.

[0031] Preferably, a twin-screw extruder is used for the melt extrusion.

[0032] More preferably, the length-to-diameter ratio of the twin-screw extruder is (38-48):1.

[0033] More preferably, the temperature of the twin-screw extruder is 80-120℃ in zone 1, 180-200℃ in zone 2, 180-220℃ in zone 3, 180-220℃ in zone 4, 180-220℃ in zone 5, 180-220℃ in zone 6, 180-220℃ in zone 7, 180-220℃ in zone 8, and 180-220℃ in zone 9.

[0034] Thirdly, the present invention provides an application of polypropylene material in automotive interiors.

[0035] In this invention, the automotive interior includes, but is not limited to, at least one of automotive door panels and center console.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows: In the maleic anhydride-grafted polypropylene system of this invention, on the one hand, by using a specific weight ratio of glutamic acid and metal salt to regulate the number of reversible dynamic bonds, namely the number of hydrogen bonds formed between carboxyl groups and the number of coordination bonds formed between metal ions and carboxyl groups, the polypropylene material can achieve reversible breakage and reconstruction of reversible dynamic bonds under thermal action, thereby improving the self-healing performance of the polypropylene material; on the other hand, the interaction of hydrogen bonds, coordination bonds and covalent bonds forms a hybrid cross-linked network structure, which strengthens the reversible breakage and reconstruction of reversible dynamic bonds, thereby improving the self-healing performance of the polypropylene material. Detailed Implementation

[0037] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0038] The experimental methods in the following examples and comparative examples, where specific conditions are not specified, are generally performed under conventional conditions in the art or as recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from the conventional market.

[0039] The reagents used in the various embodiments and comparative examples of this invention are as follows: Polypropylene resin, PP EP548R, CNOOC Shell; Maleic anhydride monomer, CAS No.: 108-31-6, commercially available; Trigonox 101, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, CAS No.: 78-63-7, commercially available; Maleic anhydride-grafted polypropylene-1 (MAH-g-PP-1), with a maleic anhydride grafting rate of 0.9%, is prepared as follows: 97 parts of polypropylene resin, 3 parts of maleic anhydride monomer, and 0.5 parts of peroxide initiator Trigonox 101 are placed in a high-speed mixer and mixed at 25°C for 7 minutes to obtain a premix; the premix is ​​then fed into a twin-screw extruder through the main feed port, and subjected to melt reaction at 220°C, devolatilization, and granulation to obtain maleic anhydride-grafted polypropylene-1 (MAH-g-PP-1). Maleic anhydride-grafted polypropylene-2 ​​(MAH-g-PP-2), with a maleic anhydride grafting rate of 0.6%, is prepared as follows: 98.2 parts of polypropylene resin, 1.8 parts of maleic anhydride monomer, and 0.5 parts of peroxide initiator Trigonox 101 are placed in a high-speed mixer and mixed at 25°C for 7 minutes to obtain a premix; the premix is ​​then fed into a twin-screw extruder through the main feed port, and subjected to melt reaction at 220°C, devolatilization, and granulation to obtain maleic anhydride-grafted polypropylene-2 ​​(MAH-g-PP-2). Maleic anhydride-grafted polypropylene-3 (MAH-g-PP-3), with a maleic anhydride grafting rate of 1.2%, is prepared as follows: 96 parts of polypropylene resin, 4 parts of maleic anhydride monomer, and 0.5 parts of peroxide initiator Trigonox 101 are placed in a high-speed mixer and mixed at 25°C for 7 minutes to obtain a premix; the premix is ​​then fed into a twin-screw extruder through the main feed port, and subjected to melt reaction at 220°C, devolatilization, and granulation to obtain maleic anhydride-grafted polypropylene-3 (MAH-g-PP-3). Maleic anhydride-grafted polypropylene-4 (MAH-g-PP-4), with a maleic anhydride grafting rate of 0.3%, is prepared as follows: 99.1 parts of polypropylene resin, 0.9 parts of maleic anhydride monomer, and 0.5 parts of peroxide initiator Trigonox 101 are placed in a high-speed mixer and mixed at 25°C for 7 minutes to obtain a premix; the premix is ​​then fed into a twin-screw extruder through the main feed port, and subjected to melt reaction at 220°C, devolatilization, and granulation to obtain maleic anhydride-grafted polypropylene-4 (MAH-g-PP-4). Maleic anhydride-grafted polypropylene-5 (MAH-g-PP-5), with a maleic anhydride grafting rate of 1.5%, is prepared as follows: 95 parts of polypropylene resin, 5 parts of maleic anhydride monomer, and 0.5 parts of peroxide initiator Trigonox 101 are placed in a high-speed mixer and mixed at 25°C for 7 minutes to obtain a premix; the premix is ​​then fed into a twin-screw extruder through the main feed port, and subjected to melt reaction at 220°C, devolatilization, and granulation to obtain maleic anhydride-grafted polypropylene-5 (MAH-g-PP-5). Glutamic acid-1, L-glutamic acid, L810368, Maclean; Glutamic acid-2, D-glutamic acid, D810325, Maclean; Ferric chloride (FeCl3), commercially available; Ferric sulfate [Fe2(SO4)3], commercially available; Ferrous chloride (FeCl2), commercially available; Calcium chloride (CaCl2), commercially available; Zinc chloride (ZnCl2), commercially available; Aluminum chloride (AlCl3), commercially available; POE-1, thermoplastic elastomer, POE ENGAGE 11527, Dow Chemical, USA; POE-2, thermoplastic elastomer, POE ENGAGE 7270, Dow Chemical, USA; Antioxidant 1010, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], commercially available; Antioxidant 168, tris(2,4-di-tert-butyl)phosphite, commercially available.

[0040] In this invention, the method for testing the maleic anhydride grafting rate in maleic anhydride-grafted polypropylene (MAH-g-PP) is acid-base titration, specifically: (1) Sample purification: Accurately weigh about 1-2 grams (denoted as m0, accurate to 0.0001 g) of MAH-g-PP powder or granules, place them in a Soxhlet extractor, and continuously extract with solvents such as acetone or xylene for 8-24 h to completely remove unreacted free maleic anhydride monomers and their oligomers; then place the purified sample in an 80℃ vacuum oven and dry to constant weight (denoted as m1, unit g); (2) Hydrolysis and saponification: Place the dried purified sample in a 250 mL Erlenmeyer flask, add 100 mL of excess xylene solution of known concentration (e.g., 0.05 mol / L, solvent is water), and heat under nitrogen protection and reflux (about 140 °C) to completely dissolve the sample; then, accurately add 25 mL of potassium hydroxide-ethanol standard solution of known concentration (e.g., 0.1 mol / L) with a pipette, and continue to reflux for more than 2 hours to ensure that the grafted maleic anhydride groups are completely hydrolyzed and generate potassium maleate salt; (3) Back titration: Cool the solution to room temperature, add 2-3 drops of phenolphthalein indicator; use a known concentration C HCl standard hydrochloric acid solutions (e.g., C) HCl Titrate with 0.1 mol / L hydrochloric acid standard solution until the pink color of the solution just disappears, and record the volume of hydrochloric acid standard solution consumed (V1, unit L). (4) Blank experiment: Without adding MAH-g-PP sample, repeat steps 2 and 3 above and record the volume of hydrochloric acid standard solution consumed in the blank experiment (V0, unit L). The maleic anhydride grafting rate (GR) in MAH-g-PP is calculated using the following formula: GR(wt%) = (V0-V1)×C HCl ×M MAH / (2×m1)×100%, where M MAH is the molecular weight of maleic anhydride.

[0041] Examples 1-14 and Comparative Examples 1-3 Examples 1-14 and Comparative Examples 1-3 provide different polypropylene materials, which differ only in the types and amounts of each component. By weight, Examples 1-14 and Comparative Examples 1-3 include the components shown in Table 1-2. The preparation methods of the polypropylene materials in Examples 1-14 and Comparative Examples 1-3 include the following steps: Mix the components, melt extrude using a twin-screw extruder (length-to-diameter ratio 40:1), granulate, and dry at 80℃ for 10 hours to obtain polypropylene material; The twin-screw extruder has the following temperatures: Zone 1: 90℃; Zone 2: 180℃; Zone 3: 200℃; Zone 4: 200℃; Zone 5: 200℃; Zone 6: 200℃; Zone 7: 200℃; Zone 8: 200℃; Zone 9: 200℃; and the main extruder speed is 450 r / min. Table 1. Weight parts of each component in polypropylene materials of Examples 1-14 Table 2 shows the weight parts of each component in the polypropylene materials of Comparative Examples 1-3. Performance testing The performance of the polypropylene materials in each embodiment and comparative example was tested, as follows: 1. Self-healing performance test: (1) Under the conditions of injection temperature of 220℃ and mold temperature of 50℃, polypropylene material was injection molded into a sample with a length of 80cm, a width of 10cm and a thickness of 4cm. (2) Make a 20mm long and 2mm deep scratch on the sample, and then bake it in a 100℃ oven for 60min to allow the polypropylene material to undergo reversible dynamic bond breakage and reconstruction under thermal action. Take it out and measure the depth of the scratch at this time, which is recorded as H (unit mm). Calculate the degree of self-healing (%) according to the following formula: Self-healing degree (%) = (2-H) / 2 × 100%; The higher the self-healing rating, the stronger the self-healing performance of the polypropylene material. 2. Elongation at break test Under the conditions of injection temperature of 220℃ and mold temperature of 50℃, polypropylene material was injection molded into a dumbbell-shaped specimen of type 1A as specified in ISO 527-2019 standard. The elongation at break of the specimen was tested at a test speed of 50 mm / min in a constant temperature and humidity environment of 23℃ and 50% relative humidity. The experimental results are shown in the table below: Table 3 Performance test results of polypropylene materials in each example and comparative example. As shown in Table 3, the polypropylene material of the present invention has good self-healing properties, specifically, the degree of self-healing is ≥60%. In addition, the polypropylene material of the present invention also has good flexibility, with an elongation at break of ≥140%.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polypropylene material, characterized in that, The components include the following parts by weight: 45-65 parts maleic anhydride-grafted polypropylene, 25-45 parts glutamic acid and metal salt, 10-25 parts thermoplastic elastomer; The weight ratio of the glutamic acid to the metal salt is 1:(0.3-1.8).

2. The polypropylene material as described in claim 1, characterized in that, The metal salt is at least one of iron salt, calcium salt, magnesium salt, copper salt, manganese salt, cobalt salt, nickel salt, zinc salt, and aluminum salt.

3. The polypropylene material as described in claim 1, characterized in that, The anion of the metal salt is at least one of chloride, nitrate, carbonate, and sulfate.

4. The polypropylene material as described in claim 1, characterized in that, The metal salt includes at least one of ferric chloride, ferric nitrate, ferric sulfate, ferrous chloride, calcium chloride, zinc chloride, and aluminum chloride.

5. The polypropylene material as described in claim 1, characterized in that, The maleic anhydride grafting rate in the maleic anhydride-grafted polypropylene is 0.1-1.8 wt%.

6. The polypropylene material as described in claim 1, characterized in that, The maleic anhydride grafting rate in the maleic anhydride-grafted polypropylene is 0.6-1.2 wt%.

7. The polypropylene material as described in claim 1, characterized in that, The polypropylene material also includes 0-3 parts of antioxidant.

8. The polypropylene material according to any one of claims 1, characterized in that, The thermoplastic elastomer includes at least one of POE, SBS, and SEBS.

9. An application of the polypropylene material as described in any one of claims 1-8 in automotive interiors.

10. The application of the polypropylene material as described in claim 9 in automotive interiors, characterized in that, The automotive interior includes at least one of the following: automotive door panels and center console.

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