Corrosion-resistant polypropylene-based composite material, preparation method thereof and application of corrosion-resistant polypropylene-based composite material in automobile fuel tank

Abstract

The invention relates to the technical field of high-performance polypropylene, and discloses a corrosion-resistant polypropylene-based composite material, a preparation method thereof and application of the corrosion-resistant polypropylene-based composite material in an automobile fuel tank. The polypropylene-based composite material comprises the following components in parts by weight: 60-90 parts of polypropylene resin, 10-40 parts of a polyphenyl ether copolymer and 0.1-0.3 part of an antioxidant, after the alkyl chain is introduced into the polyphenyl ether copolymer material, the compatibility between the polyphenyl ether copolymer material and polypropylene becomes good, the phase separation defect between the polyphenyl ether copolymer material and polypropylene is reduced, the tensile strength, bending strength and the like of the composite material can be enhanced, and the side chain of the polyphenyl ether copolymer contains a benzene ring with high structural stability, so that the strength of the composite material can be further improved. Meanwhile, the composite material is low in oil absorption rate and excellent in oil corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of high-performance polypropylene technology, specifically to a corrosion-resistant polypropylene-based composite material, its preparation method, and its application in automotive fuel tanks. Background Technology

[0002] Polypropylene (PP) has good processing performance, is easy to mold, and is inexpensive, making it widely used in automotive interior and exterior parts, plastic fuel tanks, and wires and cables. Improving the mechanical strength, oil resistance, and corrosion resistance of PP will help expand its practical applications in areas such as automotive plastic fuel tanks. Polyphenylene oxide (PPE) has the advantages of high strength, high modulus, and strong oil and corrosion resistance, and can be compounded with polymers such as polypropylene and polystyrene to create high-performance plastic alloys.

[0003] Polypropylene and polyphenylene ether have significantly different solubility parameters, resulting in poor compatibility and affecting the mechanical strength of the composite material. Patent CN108384113B discloses a polypropylene / polyphenylene ether alloy and its preparation method, using polystyrene-hydrogenated polyisoprene-polystyrene block copolymer as a compatibilizer. The prepared polypropylene / polyphenylene ether alloy exhibits good processing and mechanical properties. However, this patent requires the addition of an additional compatibilizer and does not improve the oil and corrosion resistance of the polypropylene material. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a corrosion-resistant, high-performance polypropylene-based composite material and its preparation method, which solves the problem of low strength in polypropylene materials and improves the oil corrosion resistance of polypropylene.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a corrosion-resistant polypropylene-based composite material and its preparation method, wherein the polypropylene-based composite material comprises 60-90 parts by weight of polypropylene resin, 10-40 parts by weight of polyphenylene ether copolymer, and 0.1-0.3 parts by weight of antioxidant.

[0006] The preparation method of corrosion-resistant polypropylene-based composite material is as follows:

[0007] (1) Isopropanol and cuprous bromide were added to an open reaction flask. After stirring, a chlorobenzene solution containing N,N,N',N'-tetramethyl-1,3-butanediamine was added dropwise. After stirring, a chlorobenzene solution containing 2,6-bis(4-alkylphenyl)phenol was added dropwise. The first polymerization reaction was carried out by stirring. Then, isopropanol and a chlorobenzene solution containing N,N,N',N'-tetramethyl-1,3-butanediamine were added dropwise. After stirring, a chlorobenzene solution containing 2,6-dimethylphenol was added dropwise. The second polymerization reaction was carried out by stirring. The solution was poured into a mixed solution of concentrated hydrochloric acid and methanol. After stirring, the mixture was filtered, washed with a mixed solution of concentrated hydrochloric acid and methanol, and dried to obtain a polyphenylene ether copolymer.

[0008] (2) Mix polypropylene resin, polyphenylene ether copolymer and antioxidant, melt extrude in a twin-screw extruder, and pelletize to obtain corrosion-resistant polypropylene-based composite material.

[0009] Preferably, the molar ratio of cuprous bromide, N,N,N',N'-tetramethyl-1,3-butanediamine, 2,6-bis(4-alkylphenyl)phenol and 2,6-dimethylphenol in (1) is (1.1-1.4):6-7:(10-30):(70-90).

[0010] Preferably, the temperature of the first polymerization reaction in (1) is 20-30℃ and the reaction time is 5-8h.

[0011] Preferably, the temperature of the second polymerization reaction in (1) is 20-30℃ and the reaction time is 6-10h.

[0012] Preferably, the antioxidant in (2) is antioxidant 1010, antioxidant 1076 or antioxidant 330.

[0013] Preferably, in (2), the temperature of each section of the twin-screw extruder is 180-265℃ and the screw speed is 200-400r / min.

[0014] Preferably, the preparation method of 2,6-bis(4-alkylphenyl)phenol includes the following steps: adding toluene, 2,6-dibromophenol in a ratio of 1:(2.6-3.2):(0.05-0.06):(4.6-5.4), 4-alkylphenylboronic acid, tetra(triphenylphosphine)palladium, potassium carbonate, and water to a reaction flask equipped with a reflux condenser; heating to 80-90°C; reacting for 18-24 h; adding water; extracting with dichloromethane; drying the organic layer; and separating the crude product by silica gel column chromatography to obtain 2,6-bis(4-alkylphenyl)phenol.

[0015] Preferably, the structural formula of 4-alkylphenylboronic acid is as follows: n is any integer from 4 to 8.

[0016] Preferably, corrosion-resistant polypropylene-based composite materials are used in automotive fuel tanks.

[0017] The beneficial technical effects of this invention are as follows: A copolymerization reaction of 2,6-bis(4-alkylphenyl)phenol and 2,6-dimethylphenol yields a polyphenylene ether copolymer with alkyl chains and benzene rings in its side chains. This copolymer is then blended and granulated with polypropylene to obtain a corrosion-resistant, high-performance polypropylene-based composite material. The introduction of alkyl chains into the polyphenylene ether copolymer improves its compatibility with polypropylene, reducing phase separation defects and enhancing the tensile strength, flexural strength, and other properties of the composite material without the need for compatibilizers. Furthermore, the presence of highly structurally stable benzene rings in the side chains of the polyphenylene ether copolymer further improves the strength of the composite material. Simultaneously, the composite material exhibits low oil absorption and excellent oil corrosion resistance, showing broad application prospects in areas such as automotive fuel tanks. Attached Figure Description

[0018] Figure 1 This is the infrared spectrum of the polyphenylene ether copolymer of Example 1. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] The polypropylene resin grade described below is F40-03mm, sourced from Shanghai Liuzhangyang Plastics Co., Ltd. The concentrated hydrochloric acid has a mass fraction of 37%.

[0021] Example 1:

[0022] (1) Add 0.9 L toluene, 0.2 mol 2,6-dibromophenol, 0.64 mol 4-n-butylphenylboronic acid, 10 mmol tetra(triphenylphosphine)palladium, 0.92 mol potassium carbonate and 300 mL water to a reaction flask equipped with a reflux condenser. Heat to 90 °C and stir for 18 h. Add water and extract with dichloromethane. Dry the organic layer and separate the crude product by silica gel column chromatography. Elute with petroleum ether and dichloromethane solution to obtain 2,6-bis(4-alkylphenyl)phenol.

[0023] (2) Add 120 mL of isopropanol and 12 mmol of cuprous bromide to an open reaction flask, stir, and then add 250 mL of chlorobenzene solution containing 5.2 mmol of N,N,N',N'-tetramethyl-1,3-butanediamine. Stir for 30 min, then add 200 mL of chlorobenzene solution containing 0.1 mol of 2,6-bis(4-alkylphenyl)phenol. Stir and react at 25 °C for 5 h. Then add 140 mL of isopropanol and 300 mL of chlorobenzene solution containing 57 mmol of N,N,N',N'-tetramethyl-1,3-butanediamine. Stir for 30 min, then add 0.9 L of chlorobenzene solution containing 0.9 mol of 2,6-dimethylphenol. Stir and react for 6 h. Pour the solution into a 1:100 mixture of concentrated hydrochloric acid and methanol, stir, filter, wash with a 1:100 mixture of concentrated hydrochloric acid and methanol, and dry to obtain polyphenylene ether copolymer. Figure 1 1149 cm⁻¹ in the infrared spectrum -1 It is the COC stretching vibration peak of the phenylene ether bond in the polyphenylene ether copolymer, 1493-1602 cm⁻¹. -1 It is a characteristic peak of the benzene ring skeleton, 2884 cm⁻¹ -1 and 2927cm -1 These are the absorption peaks of methyl-CH3 and methylene-CH2- in alkyl chains.

[0024] (3) Mix 9 kg of polypropylene resin, 1 kg of polyphenylene ether copolymer and 30 g of antioxidant 1076, melt extrude in a twin-screw extruder, with temperatures of 180℃, 220℃, 240℃, 255℃, 265℃ and 265℃ in each section, and screw speed of 200 r / min, and pelletize to obtain corrosion-resistant polypropylene-based composite material.

[0025] Example 2:

[0026] (1) Add 1 L of toluene, 0.2 mol of 2,6-dibromophenol, 0.52 mol of 4-pentylphenylboronic acid, 12 mmol of tetra(triphenylphosphine)palladium, 1.08 mol of potassium carbonate and 400 mL of water to a reaction flask equipped with a reflux condenser. Heat to 80 °C and stir for 24 h. Add water and extract with dichloromethane. Dry the organic layer and separate the crude product by silica gel column chromatography. Elute with petroleum ether and dichloromethane solution to obtain 2,6-bis(4-alkylphenyl)phenol.

[0027] (2) Add 130 mL of isopropanol and 11 mmol of cuprous bromide to an open reaction flask, stir, and then add 250 mL of chlorobenzene solution containing 5 mmol of N,N,N',N'-tetramethyl-1,3-butanediamine. Stir for 40 min, then add 300 mL of chlorobenzene solution containing 0.17 mol of 2,6-bis(4-alkylphenyl)phenol. Stir and react at 20 °C for 8 h. Then add 140 mL of isopropanol and 300 mL of chlorobenzene solution containing 55 mmol of N,N,N',N'-tetramethyl-1,3-butanediamine. Stir for 30 min, then add 1 L of chlorobenzene solution containing 0.83 mol of 2,6-dimethylphenol. Stir and react for 10 h. Pour the solution into a 1:100 mixture of concentrated hydrochloric acid and methanol, stir, filter, wash with a 1:100 mixture of concentrated hydrochloric acid and methanol, and dry to obtain polyphenylene ether copolymer.

[0028] (3) Mix 8 kg of polypropylene resin, 2 kg of polyphenylene ether copolymer and 17 g of antioxidant 330, melt extrude in a twin-screw extruder, with temperatures of 180℃, 220℃, 240℃, 255℃, 265℃ and 265℃ in each section, and screw speed of 400 r / min, and pelletize to obtain corrosion-resistant polypropylene-based composite material.

[0029] Example 3:

[0030] (1) Add 140 mL of isopropanol and 14 mmol of cuprous bromide to an open reaction flask, stir, and then add 300 mL of a chlorobenzene solution containing 6 mmol of N,N,N',N'-tetramethyl-1,3-butanediamine. Stir for 50 min, then add 300 mL of a chlorobenzene solution containing 0.23 mol of 2,6-bis(4-alkylphenyl)phenol (prepared according to the method of Example 1). Stir the reaction at 30 °C for 5 h, then add 140 mL of isopropanol and 400 mL of a chlorobenzene solution containing 64 mmol of N,N,N',N'-tetramethyl-1,3-butanediamine. Stir for 30 min, then add 1 L of a chlorobenzene solution containing 0.77 mol of N,N,N',N'-tetramethyl-1,3-butanediamine. A chlorobenzene solution of 2,6-dimethylphenol was stirred for 9 hours. The solution was then poured into a mixture of concentrated hydrochloric acid and methanol at a volume ratio of 1:100. After stirring, the mixture was filtered, washed with a mixture of concentrated hydrochloric acid and methanol at a volume ratio of 1:100, and dried to obtain a polyphenylene ether copolymer.

[0031] (2) Mix 7 kg of polypropylene resin, 3 kg of polyphenylene ether copolymer and 16 g of antioxidant 1010, melt extrude in a twin-screw extruder, with temperatures of 180℃, 220℃, 240℃, 255℃, 265℃ and 265℃ in each section, and screw speed of 400 r / min, and pelletize to obtain corrosion-resistant polypropylene-based composite material.

[0032] Example 4:

[0033] (1) Add 130 mL of isopropanol and 11 mmol of cuprous bromide to an open reaction flask, stir, and then add 250 mL of a chlorobenzene solution containing 5.6 mmol of N,N,N',N'-tetramethyl-1,3-butanediamine dropwise. Stir for 50 min, then add 400 mL of a chlorobenzene solution containing 0.3 mol of 2,6-bis(4-alkylphenyl)phenol (prepared according to the method of Example 1). Stir the reaction at 25 °C for 8 h, then add 140 mL of isopropanol and 400 mL of a chlorobenzene solution containing 61 mmol of N,N,N',N'-tetramethyl-1,3-butanediamine dropwise. Stir for 30 min, then add 1 L of a chlorobenzene solution containing 0.7 mol of N,N,N',N'-tetramethyl-1,3-butanediamine dropwise. A chlorobenzene solution of 2,6-dimethylphenol was stirred and reacted for 10 hours. The solution was then poured into a mixed solution of concentrated hydrochloric acid and methanol at a volume ratio of 1:100. After stirring, the mixture was filtered, washed with a mixed solution of concentrated hydrochloric acid and methanol at a volume ratio of 1:100, and dried to obtain a polyphenylene ether copolymer.

[0034] (2) Mix 6 kg of polypropylene resin, 4 kg of polyphenylene ether copolymer and 10 g of antioxidant 1076, melt extrude in a twin-screw extruder, with temperatures of 180℃, 220℃, 240℃, 255℃, 265℃ and 265℃ in each section, and screw speed of 300 r / min, and pelletize to obtain corrosion-resistant polypropylene-based composite material.

[0035] Comparative Example 1:

[0036] (1) Add 120 mL of isopropanol, 12 mmol of cuprous bromide, 140 mL of isopropanol, and 300 mL of chlorobenzene solution containing 57 mmol of N,N,N',N'-tetramethyl-1,3-butanediamine to an open reaction flask. Stir for 30 min, add 0.9 L of chlorobenzene solution containing 0.9 mol of 2,6-dimethylphenol dropwise, stir and react for 6 h. Pour the solution into a mixed solution of concentrated hydrochloric acid and methanol with a volume ratio of 1:100, stir and filter. Wash with a mixed solution of concentrated hydrochloric acid and methanol with a volume ratio of 1:100, and dry to obtain polyphenylene ether.

[0037] (2) Mix 9 kg of polypropylene resin, 1 kg of polyphenylene ether and 30 g of antioxidant 1076, melt extrude in a twin-screw extruder, with temperatures of 180℃, 220℃, 240℃, 255℃, 265℃ and 265℃ in each section, and screw speed of 200 r / min, and pelletize to obtain polypropylene-based composite material.

[0038] Comparative Example 2:

[0039] (1) Add 120 mL of isopropanol and 12 mmol of cuprous bromide to an open reaction flask, stir, and then add 250 mL of a chlorobenzene solution containing 5.2 mmol of N,N,N',N'-tetramethyl-1,3-butanediamine. Stir for 30 min, then add 200 mL of a chlorobenzene solution containing 0.1 mol of 2,6-diphenylphenol (CAS Registry No. 2432-11-3). Stir the reaction at 25 °C for 5 h, then add 140 mL of isopropanol and 300 mL of a chlorobenzene solution containing 57 mmol of N,N,N',N'-tetramethyl-1,3-butanediamine. Stir for 30 min, and then add 0.9 L of a chlorobenzene solution containing 0.9 mol of N,N,N',N'-tetramethyl-1,3-butanediamine. A chlorobenzene solution of 2,6-dimethylphenol was stirred for 6 hours. The solution was then poured into a mixture of concentrated hydrochloric acid and methanol at a volume ratio of 1:100. After stirring, the mixture was filtered, washed with a mixture of concentrated hydrochloric acid and methanol at a volume ratio of 1:100, and dried to obtain a polyphenylene ether copolymer.

[0040] (2) Mix 9 kg of polypropylene resin, 1 kg of polyphenylene ether copolymer and 30 g of antioxidant 1076, melt extrude in a twin-screw extruder, with temperatures of 180℃, 220℃, 240℃, 255℃, 265℃ and 265℃ in each section, and screw speed of 200 r / min, and pelletize to obtain polypropylene-based composite material.

[0041] Polypropylene-based composite materials were injection molded into test specimens using an injection molding machine. Tensile strength was tested according to GB / T 1040.1-2018 standard. Flexural strength was tested according to GB / T 9341-2000 standard. Cantilever beam impact strength was tested according to GB / T 1843-2008 standard.

[0042] The polypropylene-based composite material was dried and weighed, then immersed in 95-octane gasoline for 7 days. After removal, the surface was washed with dichloromethane to remove residual gasoline, the dichloromethane was dried, and the material was weighed again to calculate the oil absorption rate W. W = (mass after oil absorption - mass before oil absorption) ÷ mass before oil absorption × 100%. The lower the oil absorption rate, the better the oil corrosion resistance.

[0043] Table 1 Properties of polypropylene-based composites

[0044] Tensile strength (MPa) Bending strength (MPa) <![CDATA[Impact strength (kJ / m 2 )]]> Oil absorption rate (%) Example 1 32.4 41.5 9.1 0.108 Example 2 38.7 52.9 8.3 0.091 Example 3 43.6 60.0 6.8 0.063 Example 4 47.3 64.8 5.3 0.085 Comparative Example 1 28.1 36.6 8.5 0.127 Comparative Example 2 29.2 38.1 8.3 0.125

[0045] Tests showed that the polypropylene-based composite material in Comparative Example 1 had low tensile strength, flexural strength, and impact strength. This was mainly because the solubility parameters of polypropylene and polyphenylene ether differed significantly, resulting in poor compatibility. This severely affected the mechanical strength of the composite material. Furthermore, phase separation between the two materials created structural defects, allowing gasoline molecules to enter the composite matrix, increasing oil absorption and reducing oil corrosion resistance.

[0046] Each embodiment utilizes 2,6-bis(4-alkylphenyl)phenol and 2,6-dimethylphenol for copolymerization, introducing alkyl chains into the side chains of the polyphenylene ether copolymer. This improves the compatibility between polyphenylene ether and polypropylene, reduces phase separation defects between the two, enhances the mechanical strength of the composite material, reduces oil absorption, and improves oil corrosion resistance. Furthermore, the side chains of the polyphenylene ether copolymer contain benzene rings with high structural stability, which can further improve the strength of the composite material.

[0047] Comparative Example 2 prepared a polyphenylene ether copolymer by copolymerizing conventional 2,6-diphenylphenol and 2,6-dimethylphenol. The copolymer did not contain alkyl chains, had poor compatibility with polypropylene, and the composite material had low strength and high oil absorption.

[0048] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A corrosion-resistant polypropylene-based composite material, characterized in that, The polypropylene-based composite material comprises 60-90 parts by weight of polypropylene resin, 10-40 parts by weight of polyphenylene ether copolymer, and 0.1-0.3 parts by weight of antioxidant; The preparation method of the polyphenylene ether copolymer includes the following steps: adding isopropanol and cuprous bromide to a reaction flask, stirring, and then adding a chlorobenzene solution containing N,N,N',N'-tetramethyl-1,3-butanediamine dropwise; stirring, and then adding a chlorobenzene solution containing 2,6-bis(4-alkylphenyl)phenol dropwise; stirring to carry out the first polymerization reaction; then adding isopropanol and a chlorobenzene solution containing N,N,N',N'-tetramethyl-1,3-butanediamine dropwise; stirring, and then adding a chlorobenzene solution containing 2,6-dimethylphenol dropwise; stirring to carry out the second polymerization reaction; pouring the solution into a mixed solution of concentrated hydrochloric acid and methanol; stirring, filtering, washing, and drying to obtain the polyphenylene ether copolymer; The structural formula of the 2,6-bis(4-alkylphenyl)phenol is as follows: n is any integer from 4 to 8.

2. The high-strength polypropylene composite material according to claim 1, characterized in that, The antioxidant is antioxidant 1010, antioxidant 1076, or antioxidant 330.

3. The corrosion-resistant polypropylene-based composite material according to claim 1, characterized in that, The molar ratio of cuprous bromide, N,N,N',N'-tetramethyl-1,3-butanediamine, 2,6-bis(4-alkylphenyl)phenol, and 2,6-dimethylphenol is (1.1-1.4):6-7:(10-30):(70-90).

4. The corrosion-resistant polypropylene-based composite material according to claim 1, characterized in that, The temperature of the first polymerization reaction is 20-30℃, and the reaction time is 5-8h; the temperature of the second polymerization reaction is 20-30℃, and the reaction time is 6-10h.

5. The corrosion-resistant polypropylene-based composite material according to claim 1, characterized in that, The preparation method of 2,6-bis(4-alkylphenyl)phenol includes the following steps: adding toluene, 2,6-dibromophenol, 4-alkylphenylboronic acid, tetra(triphenylphosphine)palladium, potassium carbonate and water to a reaction flask equipped with a reflux condenser, heating to 80-90℃, reacting for 18-24 h, and separating the crude product by silica gel column chromatography to obtain 2,6-bis(4-alkylphenyl)phenol.

6. The corrosion-resistant polypropylene-based composite material according to claim 5, characterized in that, The molar ratio of 2,6-dibromophenol, 4-alkylphenylboronic acid, tetrakis(triphenylphosphine)palladium, and potassium carbonate is 1:(2.6-3.2):(0.05-0.06):(4.6-5.4).

7. The corrosion-resistant polypropylene-based composite material according to claim 6, characterized in that, The structural formula of the 4-alkylphenylboronic acid is as follows: n is any integer from 4 to 8.

8. A method for preparing a corrosion-resistant polypropylene-based composite material as described in any one of claims 1-7, characterized in that, The preparation method includes the following steps: mixing polypropylene resin, polyphenylene ether copolymer, and antioxidant, melting and extruding in a twin-screw extruder, and pelletizing to obtain a corrosion-resistant polypropylene-based composite material.

9. The method for preparing the corrosion-resistant polypropylene-based composite material according to claim 8, characterized in that, The temperature of each section of the twin-screw extruder is 180-265℃, and the screw speed is 200-400 r / min.

10. The application of the corrosion-resistant polypropylene-based composite material obtained by the preparation method according to claim 9 in automobile fuel tanks.

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