Aging-resistant recycled pp composite material and preparation method thereof

Abstract

The application discloses an anti-aging recycled PP composite material and a preparation method thereof. The composite material comprises the following raw materials in parts by weight: recycled PP material 80-100 parts, high-density polyethylene 10-15 parts, modified additive 2-3 parts, and dicumyl peroxide 0.5-1 part. In the raw material melting and blending process, the modified additive is grafted with the molecules of the recycled PP material and the high-density polyethylene under the action of the dicumyl peroxide. The modified additive contains a hindered amine structure and a nickel complex structure in the molecules. The hindered amine structure is oxidized into a nitrogen-oxygen free radical under the conditions of light or thermal oxidation. The free radical can efficiently capture alkyl free radicals and alkoxy free radicals generated in the process of PP light aging, and block the free radical chain reaction. The nickel complex structure can capture excited state molecules generated in the process of PP light aging. After capturing energy, the nickel complex converts the energy into heat energy through non-radiative transition and releases the heat energy, thereby preventing the excited state molecules from causing PP chain rupture or oxidation reaction.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of PP material preparation, in particular to an anti-aging recycled PP composite material and a preparation method thereof. BACKGROUND

[0002] Polypropylene is one of the five general-purpose plastics with the fastest development, has excellent comprehensive performance, low price and cost, various types, large output, high performance-price ratio, good chemical stability, and is easy to process and form and recycle. Because of its good chemical stability, it is stable in contact with other chemical reagents except concentrated sulfuric acid and concentrated nitric acid. With the increase of the material usage rate, the scrap rate also increases. Therefore, recycling of the scrapped PP material has become a common means for solving the environmental impact of the PP material at the present stage. However, because there are a large number of tertiary carbon atoms with methyl groups on the PP molecular chain, the C-H bond energy is low, and the PP material is easy to be attacked and broken by heat, oxygen and ultraviolet light, free radicals are generated to initiate chain reactions, which reduces the service life of the PP material, thereby limiting the application of the recycled PP in various fields. SUMMARY

[0003] The application aims to provide an anti-aging recycled PP composite material and a preparation method thereof, and solve the problem of poor anti-aging effect of the recycled PP composite material at the present stage.

[0004] The purpose of the application can be achieved by the following technical solutions.

[0005] A preparation method of an anti-aging recycled PP composite material, specifically comprising the following steps:

[0006] Step A1: uniformly mix tetramethylpiperidinol, ethyl acrylate, tetrabutyl titanate and dimethylbenzene, protect with nitrogen, and react under the conditions of a rotation speed of 200-300 r / min and a temperature of 120-125 DEG C for 4-6 h to prepare a modifier; uniformly mix the modifier, modified polysiloxane, chloroplatinic acid and DMF, protect with nitrogen, and react under the conditions of a rotation speed of 120-150 r / min and a temperature of 70-80 DEG C for 3-5 h to prepare a functionalized polysiloxane;

[0007] Step A2: mix maleic anhydride and DMF, stir under the conditions of a rotation speed of 200-300 r / min and a temperature of 5-10 DEG C, and then add the functionalized polysiloxane; heat to 55-60 DEG C, react for 30-40 min, and then add triethylamine, acetic anhydride and nickel acetate; continue to react for 2-3 h to prepare an additive; uniformly mix the additive, 2,2'-thiobis-p-tert-octylphenol, nickel acetate and DMF, and react under the conditions of a rotation speed of 200-300 r / min and a temperature of 50-60 DEG C for 2-3 h to prepare a modified additive;

[0008] Step A3: the following weight parts of raw materials are weighed: recycled PP material 80-100 parts, high-density polyethylene 10-15 parts, modified additive 2-3 parts, and dicumyl peroxide 0.5-1 part, the raw materials are added into a twin-screw extruder, and an aging-resistant recycled PP composite material is prepared by extrusion under the conditions of die head temperature 200℃, first zone temperature 170℃, second zone temperature 180℃, third zone temperature 190℃, fourth zone temperature 200℃, and fifth zone temperature 200℃.

[0009] Further, the molar ratio of tetramethylpiperidinol and ethyl acrylate in step A1 is 1:3, the amount of tetrabutyl titanate is 1% of the mass sum of tetramethylpiperidinol and ethyl acrylate, the molar ratio of the modifier and Si-H bonds on the modified polysiloxane is 1:1, and the amount of chloroplatinic acid is 1‰ of the mass of the modifier.

[0010] Further, the amounts of maleic anhydride, functionalized polysiloxane, triethylamine, acetic anhydride, and nickel acetate in step A2 are 56 mmol: 28 mmol: 5 mL: 12 mL: 3.5 g, and the molar ratio of the additive, 2,2'-thiobis-p-tert-octylphenol, and nickel acetate is 30:9:11.

[0011] Further, the modified polysiloxane is prepared by the following steps:

[0012] Step B1: diphenyldichlorosilane and dichloromethane are uniformly mixed, nitrogen protection is performed, stirring is performed at a rotation speed of 150-200 r / min and a temperature of 0-5℃, mixed acid and copper sulfate are added, the temperature is raised to 40-45℃, and reaction is performed for 5-7 h to prepare intermediate 1; 4-bromostyrene, dimethylhydrogen chlorosilane, chloroplatinic acid, and toluene are uniformly mixed, nitrogen protection is performed, stirring is performed at a rotation speed of 120-150 r / min and a temperature of 70-80℃, and reaction is performed for 4-6 h to prepare intermediate 2;

[0013] Step B2: intermediate 2 and deionized water are mixed, nitrogen protection is performed, stirring is performed at a rotation speed of 300-500 r / min and a temperature of 0-5℃ for 10-15 min, the temperature is raised to 20-25℃, stirring is performed for 1-1.5 h, lithium hydride and tetrahydrofuran are added, and reaction is continued for 4-6 h to prepare intermediate 3; intermediate 3 and tetrahydrofuran are uniformly mixed, stirring is performed at a rotation speed of 120-150 r / min and a temperature of 0℃, tetramethylcyclotetrasiloxane is added, the temperature is raised to 25-30℃, reaction is performed for 7-9 h, intermediate 1 is added, and reaction is continued for 2-3 h to prepare polysiloxane;

[0014] Step B3: the polysiloxane, potassium hydroxide and DMF are uniformly mixed, and the reaction is carried out at a rotation speed of 150-200 r / min and a temperature of 100-110 DEG C for 10-15 h to obtain pretreated polysiloxane; the pretreated polysiloxane, palladium-carbon catalyst, triethylamine and DMF are uniformly mixed, hydrogen is introduced to maintain a pressure of 0.5-1 MPa, and the reaction is carried out at a rotation speed of 120-150 r / min and a temperature of 40-50 DEG C for 3-5 h to obtain modified polysiloxane.

[0015] Further, the amount ratio of the diphenyldichlorosilane, mixed acid and copper sulfate in step B1 is 1 mol:300 mL:5 mmol, the mixed acid is nitric acid with a mass fraction of 68% and sulfuric acid with a mass fraction of 98% mixed at a volume ratio of 1:1.5, the molar ratio of 4-bromostyrene and dimethylhydrogen chlorosilane is 1:1, and the amount of chloroplatinic acid is 1 ‰ of the mass of dimethylhydrogen chlorosilane.

[0016] Further, the amount ratio of the intermediate 2, deionized water and lithium hydride in step B2 is 1 mol:20 mL:1.05 mol, and the molar ratio of the intermediate 3, tetramethylcyclotetrasiloxane and the intermediate 1 is 2:5:1.

[0017] Further, the molar ratio of the polysiloxane, potassium hydroxide and DMF in step B3 is 1:3:15, and the amount ratio of the pretreated polysiloxane, palladium-carbon catalyst, triethylamine and DMF is 10 mmol:200 mg:1 mg:80 mL.

[0018] The application has the following beneficial effects: the disclosed anti-aging recycled PP composite material comprises the following raw materials: recycled PP material, high-density polyethylene, modified additive and dicumyl peroxide, the modified additive is prepared by ester exchange reaction of tetramethylpiperidinol and ethyl acrylate as raw materials, the modified additive and modified polysiloxane are reacted, the double bond on the modified additive and the Si-H bond on the modified polysiloxane are reacted, functionalized polysiloxane is prepared, maleic anhydride and the functionalized polysiloxane are reacted, the ring opening of the maleic anhydride and the amino group on the functionalized polysiloxane are reacted, the maleimide is formed by ring closing, the additive is prepared, the nickel type complex is formed by the reaction of the additive, 2,2'-thiobis-p-tert-octylphenol and nickel acetate, and the modified additive is prepared.

[0019] The modified polysiloxane is prepared by the following steps: nitration treatment of the raw material diphenyldichlorosilane with mixed acid to obtain intermediate 1, reaction of 4-bromostyrene and dimethylhydrogen chlorosiloxane to make the double bond on 4-bromostyrene react with the Si-H bond on dimethylhydrogen chlorosiloxane to obtain intermediate 2, hydrolysis of intermediate 2 to generate silanol, and then lithiation reaction of the silanol with lithium hydride to obtain intermediate 3, reaction of intermediate 3 as an initiator and tetramethylcyclotetrasiloxane as a polymerization monomer to obtain polysiloxane, reaction of the polysiloxane and DMF under the action of potassium hydroxide to form a dimethylaniline structure, and preparation of pretreated polysiloxane by reduction of the pretreated polysiloxane with hydrogen gas and a palladium-carbon catalyst to convert the nitro group into an amino group.

[0020] During the raw material melt blending process, the modification additive is grafted with the molecules of the recycled PP material and high-density polyethylene under the action of dicumyl peroxide, the modification additive molecule contains a hindered amine structure and a nickel complex structure, the hindered amine structure is oxidized into a nitroxyl radical under the conditions of light or thermal oxidation, the radical can efficiently capture alkyl radicals and alkoxy radicals generated during the PP light aging process to form a stable hindered piperidine oxygen-terminated polymer segment, thereby blocking the radical chain reaction, and the nickel complex structure captures the excited state molecules generated during the PP light aging process through its d-orbital electron structure, after capturing the energy, the nickel complex converts the energy into heat energy through non-radiative transition and is released, thereby preventing the excited state molecules from initiating PP chain scission or oxidation reaction, and further enabling the prepared composite material to have good aging resistance. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0022] Embodiment 1 is a preparation method of an aging-resistant recycled PP composite material, specifically comprising the following steps:

[0023] Step A1: uniformly mixing tetramethylpiperidinol, ethyl acrylate, tetrabutyl titanate and dimethylbenzene, introducing nitrogen protection, and performing reaction under the conditions of a rotation speed of 200 r / min and a temperature of 120 DEG C for 4 h to obtain a modifier, uniformly mixing the modifier, modified polysiloxane, chloroplatinic acid and DMF, introducing nitrogen protection, and performing reaction under the conditions of a rotation speed of 120 r / min and a temperature of 70 DEG C for 3 h to obtain functionalized polysiloxane;

[0024] Step A2: maleic anhydride and DMF were mixed, stirring was carried out at a rotation speed of 200 r / min and a temperature of 5℃, and then the functionalized polysiloxane was added, the temperature was raised to 55℃, and the reaction was carried out for 30 min, then triethylamine, acetic anhydride and nickel acetate were added, and the reaction was continued for 2 h to obtain the additive; the additive, 2,2'-thiobis-p-tert-octylphenol, nickel acetate and DMF were uniformly mixed, and the reaction was carried out at a rotation speed of 200 r / min and a temperature of 50℃ for 2 h to obtain the modified additive;

[0025] Step A3: the following raw materials were weighed: 80 parts of recycled PP material, 10 parts of high-density polyethylene, 2 parts of modified additive and 0.5 part of dicumyl peroxide, and the raw materials were added to a twin-screw extruder, and extruded under the conditions of a die head temperature of 200℃, a first zone temperature of 170℃, a second zone temperature of 180℃, a third zone temperature of 190℃, a fourth zone temperature of 200℃ and a fifth zone temperature of 200℃ to obtain the anti-aging recycled PP composite material.

[0026] The molar ratio of tetramethylpiperidinol to ethyl acrylate in step A1 was 1:3, the amount of tetrabutyl titanate was 1% of the mass sum of tetramethylpiperidinol and ethyl acrylate, the molar ratio of the modifier to the Si-H bond on the modified polysiloxane was 1:1, and the amount of chloroplatinic acid was 1‰ of the mass of the modifier.

[0027] The amount of maleic anhydride, functionalized polysiloxane, triethylamine, acetic anhydride and nickel acetate in step A2 was 56 mmol:28 mmol:5 mL:12 mL:3.5 g, and the molar ratio of the additive, 2,2'-thiobis-p-tert-octylphenol and nickel acetate was 30:9:11.

[0028] The modified polysiloxane was prepared by the following steps:

[0029] Step B1: diphenyldichlorosilane and dichloromethane were uniformly mixed, nitrogen protection was carried out, stirring was carried out at a rotation speed of 150 r / min and a temperature of 0℃, and then mixed acid and copper sulfate were added, the temperature was raised to 40℃, and the reaction was carried out for 5 h to obtain intermediate 1; 4-bromostyrene, dimethylhydrogen chlorosilane, chloroplatinic acid and toluene were uniformly mixed, nitrogen protection was carried out, the reaction was carried out at a rotation speed of 120 r / min and a temperature of 70℃ for 4 h to obtain intermediate 2;

[0030] Step B2: Intermediate 2 and deionized water were mixed, protected by nitrogen, stirred for 10 min at 300 r / min and 0℃, then warmed to 20℃ and stirred for 1 h, then added lithium hydride and tetrahydrofuran, and continued to react for 4 h to obtain intermediate 3. Intermediate 3 and tetrahydrofuran were mixed uniformly, stirred at 120 r / min and 0℃, then added tetramethylcyclotetrasiloxane, warmed to 25℃, reacted for 7 h, then added intermediate 1, and continued to react for 2 h to obtain polysiloxane.

[0031] Step B3: Polysiloxane, potassium hydroxide and DMF were mixed uniformly, reacted for 10 h at 150 r / min and 100℃ to obtain pretreated polysiloxane. The pretreated polysiloxane, palladium-carbon catalyst, triethylamine and DMF were mixed uniformly, hydrogen was introduced to maintain a pressure of 0.5 MPa, reacted for 3 h at 120 r / min and 40℃ to obtain modified polysiloxane.

[0032] The amount ratio of diphenyldichlorosilane, mixed acid and copper sulfate in step B1 was 1 mol:300 mL:5 mmol. The mixed acid was prepared by mixing nitric acid with a mass fraction of 68% and sulfuric acid with a mass fraction of 98% at a volume ratio of 1:1.5. The molar ratio of 4-bromostyrene and dimethylhydrogen chlorosilane was 1:1. The amount of chloroplatinic acid was 1 ‰ of the mass of dimethylhydrogen chlorosilane.

[0033] The amount ratio of intermediate 2, deionized water and lithium hydride in step B2 was 1 mol:20 mL:1.05 mol. The molar ratio of intermediate 3, tetramethylcyclotetrasiloxane and intermediate 1 was 2:5:1.

[0034] The molar ratio of polysiloxane, potassium hydroxide and DMF in step B3 was 1:3:15. The amount ratio of pretreated polysiloxane, palladium-carbon catalyst, triethylamine and DMF was 10 mmol:200 mg:1 mg:80 mL.

[0035] Example 2, a method for preparing an anti-aging recycled PP composite material, specifically comprising the following steps:

[0036] Step A1: Tetramethylpiperidinol, ethyl acrylate, tetrabutyl titanate and dimethylbenzene were mixed uniformly, protected by nitrogen, reacted for 5 h at 200 r / min and 125℃ to obtain a modifier. The modifier, modified polysiloxane, chloroplatinic acid and DMF were mixed uniformly, protected by nitrogen, reacted for 4 h at 120 r / min and 75℃ to obtain functionalized polysiloxane.

[0037] Step A2: maleic anhydride and DMF were mixed, stirring at a rotation speed of 200 r / min and a temperature of 8℃, and then the functionalized polysiloxane was added, and the reaction was carried out at a temperature of 55℃ for 35 min, then triethylamine, acetic anhydride and nickel acetate were added, and the reaction was continued for 3 h to obtain the additive; the additive, 2,2'-thiobis-p-tert-octylphenol, nickel acetate and DMF were mixed uniformly, and the reaction was carried out at a rotation speed of 200 r / min and a temperature of 55℃ for 3 h to obtain the modified additive;

[0038] Step A3: the following raw materials were weighed: 90 parts of recycled PP material, 13 parts of high-density polyethylene, 2 parts of modified additive and 0.8 parts of dicumyl peroxide, and the raw materials were added to a twin-screw extruder, and the extrusion was carried out under the following conditions: die head temperature 200℃, first zone temperature 170℃, second zone temperature 180℃, third zone temperature 190℃, fourth zone temperature 200℃ and fifth zone temperature 200℃ to obtain the anti-aging recycled PP composite material.

[0039] The molar ratio of tetramethylpiperidinol to ethyl acrylate in step A1 is 1:3, the amount of tetrabutyl titanate is 1% of the mass sum of tetramethylpiperidinol and ethyl acrylate, the molar ratio of the modifier to the Si-H bond on the modified polysiloxane is 1:1, and the amount of chloroplatinic acid is 1‰ of the mass of the modifier.

[0040] The amount of maleic anhydride, functionalized polysiloxane, triethylamine, acetic anhydride and nickel acetate in step A2 is 56 mmol:28 mmol:5 mL:12 mL:3.5 g, and the molar ratio of the additive, 2,2'-thiobis-p-tert-octylphenol and nickel acetate is 30:9:11.

[0041] The modified polysiloxane is prepared by the following steps:

[0042] Step B1: diphenyldichlorosilane and dichloromethane were mixed uniformly, and then mixed acid and copper sulfate were added under stirring at a rotation speed of 200 r / min and a temperature of 0℃, and the reaction was carried out at a temperature of 45℃ for 6 h to obtain intermediate 1; 4-bromostyrene, dimethylhydrogen chlorosilane, chloroplatinic acid and toluene were mixed uniformly, and the reaction was carried out at a rotation speed of 120 r / min and a temperature of 75℃ for 5 h to obtain intermediate 2;

[0043] Step B2: Intermediate 2 and deionized water were mixed, protected by nitrogen, stirred for 10 min at 300 r / min and 5℃, then warmed to 25℃ and stirred for 1.3 h, then added lithium hydride and tetrahydrofuran, continued to react for 5 h, to obtain intermediate 3, which was mixed with tetrahydrofuran, stirred at 120 r / min and 0℃, then added tetramethylcyclotetrasiloxane, warmed to 25℃, reacted for 8 h, then added intermediate 1, and continued to react for 3 h, to obtain polysiloxane;

[0044] Step B3: The polysiloxane, potassium hydroxide and DMF were mixed uniformly, reacted for 13 h at 150 r / min and 105℃, to obtain pretreated polysiloxane, which was mixed with palladium-carbon catalyst, triethylamine and DMF, protected by hydrogen at 0.8 MPa, reacted for 4 h at 120 r / min and 45℃, to obtain modified polysiloxane.

[0045] The amount ratio of diphenyldichlorosilane, mixed acid and copper sulfate in step B1 was 1 mol:300 mL:5 mmol, the mixed acid was prepared by mixing nitric acid with mass fraction of 68% and sulfuric acid with mass fraction of 98% at a volume ratio of 1:1.5, the molar ratio of 4-bromostyrene and dimethylhydrogen chlorosilane was 1:1, and the amount of chloroplatinic acid was 1 ‰ of the mass of dimethylhydrogen chlorosilane.

[0046] The amount ratio of intermediate 2, deionized water and lithium hydride in step B2 was 1 mol:20 mL:1.05 mol, and the molar ratio of intermediate 3, tetramethylcyclotetrasiloxane and intermediate 1 was 2:5:1.

[0047] The molar ratio of polysiloxane, potassium hydroxide and DMF in step B3 was 1:3:15, and the amount ratio of pretreated polysiloxane, palladium-carbon catalyst, triethylamine and DMF was 10 mmol:200 mg:1 mg:80 mL.

[0048] Example 3, a preparation method of an anti-aging recycled PP composite material, specifically comprising the following steps:

[0049] Step A1: Tetramethylpiperidinol, ethyl acrylate, tetrabutyl titanate and dimethylbenzene were mixed uniformly, protected by nitrogen, reacted for 6 h at 300 r / min and 125℃, to obtain a modifier, which was mixed with modified polysiloxane, chloroplatinic acid and DMF, protected by nitrogen, reacted for 5 h at 150 r / min and 80℃, to obtain functionalized polysiloxane.

[0050] Step A2: maleic anhydride and DMF were mixed, stirred at a rotation speed of 300 r / min and a temperature of 10℃, and then functionalized polysiloxane was added, the temperature was raised to 60℃, and the reaction was carried out for 40 min, then triethylamine, acetic anhydride and nickel acetate were added, and the reaction was continued for 3 h to obtain an additive; the additive, 2,2'-thiobis-p-tert-octylphenol, nickel acetate and DMF were uniformly mixed, and the reaction was carried out at a rotation speed of 300 r / min and a temperature of 60℃ for 3 h to obtain a modified additive;

[0051] Step A3: the following raw materials were weighed: 100 parts of recycled PP material, 15 parts of high-density polyethylene, 3 parts of modified additive and 1 part of dicumyl peroxide; the raw materials were added to a twin-screw extruder, and extruded under the following conditions: die head temperature 200℃, first zone temperature 170℃, second zone temperature 180℃, third zone temperature 190℃, fourth zone temperature 200℃ and fifth zone temperature 200℃ to obtain an anti-aging recycled PP composite material.

[0052] The molar ratio of tetramethylpiperidinol to ethyl acrylate in step A1 was 1:3, the amount of tetrabutyl titanate was 1% of the mass sum of tetramethylpiperidinol and ethyl acrylate, the molar ratio of the modifier to the Si-H bond on the modified polysiloxane was 1:1, and the amount of chloroplatinic acid was 1‰ of the mass of the modifier.

[0053] The amount of maleic anhydride, functionalized polysiloxane, triethylamine, acetic anhydride and nickel acetate in step A2 was 56 mmol: 28 mmol: 5 mL: 12 mL: 3.5 g, and the molar ratio of the additive, 2,2'-thiobis-p-tert-octylphenol and nickel acetate was 30:9:11.

[0054] The modified polysiloxane was prepared by the following steps:

[0055] Step B1: diphenyldichlorosilane and dichloromethane were uniformly mixed, protected by nitrogen, stirred at a rotation speed of 200 r / min and a temperature of 5℃, and then mixed acid and copper sulfate were added, the temperature was raised to 45℃, and the reaction was carried out for 7 h to obtain intermediate 1; 4-bromostyrene, dimethylhydrogen chlorosilane, chloroplatinic acid and toluene were uniformly mixed, protected by nitrogen, and the reaction was carried out at a rotation speed of 150 r / min and a temperature of 80℃ for 6 h to obtain intermediate 2;

[0056] Step B2: Intermediate 2 and deionized water were mixed, protected by nitrogen, stirred at 500 r / min for 15 min at 5℃, then warmed to 25℃, stirred for 1.5 h, then added lithium hydride and tetrahydrofuran, continued to react for 6 h, to obtain intermediate 3. Intermediate 3 and tetrahydrofuran were mixed uniformly, stirred at 50 r / min at 0℃, then added tetramethylcyclotetrasiloxane, warmed to 30℃, reacted for 9 h, then added intermediate 1, continued to react for 3 h, to obtain polysiloxane.

[0057] Step B3: Polysiloxane, potassium hydroxide and DMF were mixed uniformly, reacted at 200 r / min at 110℃ for 15 h, to obtain pretreated polysiloxane. The pretreated polysiloxane, palladium-carbon catalyst, triethylamine and DMF were mixed uniformly, hydrogen was introduced to maintain a pressure of 1 MPa, reacted at 150 r / min at 50℃ for 5 h, to obtain modified polysiloxane.

[0058] The amount ratio of diphenyldichlorosilane, mixed acid and copper sulfate in step B1 was 1 mol: 300 mL: 5 mmol, the mixed acid was prepared by mixing nitric acid with a mass fraction of 68% and sulfuric acid with a mass fraction of 98% at a volume ratio of 1:1.5, the molar ratio of 4-bromostyrene and dimethylhydrochlorosilane was 1:1, and the amount of chloroplatinic acid was 1 ‰ of the mass of dimethylhydrochlorosilane.

[0059] The amount ratio of intermediate 2, deionized water and lithium hydride in step B2 was 1 mol: 20 mL: 1.05 mol, and the molar ratio of intermediate 3, tetramethylcyclotetrasiloxane and intermediate 1 was 2:5:1.

[0060] The molar ratio of polysiloxane, potassium hydroxide and DMF in step B3 was 1:3:15, and the amount ratio of pretreated polysiloxane, palladium-carbon catalyst, triethylamine and DMF was 10 mmol: 200 mg: 1 mg: 80 mL.

[0061] Comparative Example 1: In this comparative example, the functionalized polysiloxane was used instead of the additive, and the other steps were the same as in Example 1.

[0062] Comparative Example 2: In this comparative example, the additive was used instead of the modified additive, and the other steps were the same as in Example 1.

[0063] Comparative Example 3: In this comparative example, the modified polysiloxane was used instead of the functionalized polysiloxane, and the other steps were the same as in Example 1.

[0064] The composite materials prepared from Examples 1-3 and Comparative Examples 1-3 were made into samples with a size of 120 mm x 25 mm x 4 mm according to the standard of GB / T1040.2-2022, and the tensile rate was 5 mm. The tensile strength was detected, and after aging for 3000 h under the condition of irradiation intensity of 340 nm according to the standard of ASTM G154-06, the tensile strength was detected again, and the residual rate of the tensile strength was calculated. The detection results are shown in Table 1 below.

[0065] Table 1

[0066]

[0067] From the above Table 1, it can be seen that the present application has good aging resistance effect.

[0068] The above content is only an example and explanation of the concept of the present application. Those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace them, as long as they do not deviate from the concept of the present application or exceed the scope defined by the present claims, which shall belong to the protection scope of the present application.

Claims

1. A method for preparing an aging-resistant recyclable PP composite material, characterized in that: Specifically, the steps include the following: Step A1: Tetramethylpiperidinol, ethyl acrylate, tetrabutyl titanate and xylene are mixed evenly, and the mixture is purged with nitrogen to carry out the reaction to obtain the modifier. The modifier, modified polysiloxane, chloroplatinic acid and DMF are mixed evenly, and the mixture is purged with nitrogen to carry out the reaction to obtain the functionalized polysiloxane. Step A2: Mix maleic anhydride and DMF and add functionalized polysiloxane. After reaction, add triethylamine, acetic anhydride and nickel acetate and continue the reaction to obtain the additive. Mix the additive, 2,2'-thiobis(-tert-octylphenol), nickel acetate and DMF and react to obtain the modified additive. Step A3: Weigh the following raw materials in parts by weight: 80-100 parts recycled PP material, 10-15 parts high-density polyethylene, 2-3 parts modified additives and 0.5-1 parts dicumyl peroxide. Add the raw materials to a twin-screw extruder and extrude to obtain an aging-resistant recycled PP composite material. The modified polysiloxane is prepared by the following steps: Step B1: Mix diphenyl dichlorosilane and dichloromethane evenly, purge with nitrogen, stir and add mixed acid and copper sulfate to react and obtain intermediate 1. Mix 4-bromostyrene, dimethylhydrochlorosilane, chloroplatinic acid and toluene evenly, purge with nitrogen to react and obtain intermediate 2. Step B2: Mix intermediate 2 with deionized water, purge with nitrogen for protection, stir, add lithium hydride and tetrahydrofuran, continue the reaction to obtain intermediate 3, mix intermediate 3 with tetrahydrofuran and add tetramethylcyclotetrasiloxane, react, add intermediate 1, continue the reaction to obtain polysiloxane. Step B3: Mix polysiloxane, potassium hydroxide and DMF to prepare pretreated polysiloxane. Mix the pretreated polysiloxane, palladium on carbon catalyst, triethylamine and DMF evenly and react them under hydrogen atmosphere to prepare modified polysiloxane. The mixed acid mentioned in step B1 is prepared by mixing 68% nitric acid and 98% sulfuric acid by volume in a ratio of 1:1.

5.

2. The method for preparing an aging-resistant recyclable PP composite material according to claim 1, characterized in that: The molar ratio of tetramethylpiperidinol and ethyl acrylate in step A1 is 1:3, and the molar ratio of the modifier and the Si-H bond on the modified polysiloxane is 1:

1.

3. The method for preparing an aging-resistant recyclable PP composite material according to claim 1, characterized in that: The ratio of maleic anhydride, functionalized polysiloxane, triethylamine, acetic anhydride and nickel acetate in step A2 is 56 mmol:28 mmol:5 mL:12 mL:3.5 g, and the molar ratio of additives, 2,2'-thiobis(tert-octylphenol) and nickel acetate is 30:9:

11.

4. The method for preparing an aging-resistant recyclable PP composite material according to claim 1, characterized in that: The ratio of diphenyldichlorosilane, mixed acid and copper sulfate used in step B1 is 1 mol: 300 mL: 5 mmol, and the molar ratio of 4-bromostyrene and dimethylhydrochlorosilane is 1:

1.

5. The method for preparing an aging-resistant recyclable PP composite material according to claim 1, characterized in that: In step B2, the molar ratio of intermediate 2, deionized water, and lithium hydride is 1 mol: 20 mL: 1.05 mol, and the molar ratio of intermediate 3, tetramethylcyclotetrasiloxane, and intermediate 1 is 2:5:

1.

6. The method for preparing an aging-resistant recyclable PP composite material according to claim 1, characterized in that: The molar ratio of polysiloxane, potassium hydroxide and DMF in step B3 is 1:3:15, and the ratio of pretreated polysiloxane, palladium on carbon catalyst, triethylamine and DMF is 10 mmol:200 mg:1 mg:80 mL.

7. An aging-resistant recyclable PP composite material, characterized in that: It is prepared according to any one of the preparation methods described in claims 1-6.

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