Modified polypropylene composition and preparation method thereof

Abstract

The invention relates to the technical field of high polymer materials, in particular to a modified polypropylene composition and a preparation method thereof. The modified polypropylene composition is prepared from the following raw materials in parts by weight: 68 to 88 parts of polypropylene, 5 to 15 parts of a toughening agent, 5 to 10 parts of a flame retardant, 1 to 5 parts of a compatibilizer, 0.2 to 0.5 part of modified molybdenum disulfide, 0.2 to 0.5 part of an antioxidant and 0.1 to 0.5 part of a processing aid. The modified polypropylene composition has excellent flame retardance, light aging resistance and mechanical properties.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a modified polypropylene composition and a preparation method thereof. Background Art

[0002] Polypropylene (PP) is widely used in various industries, including electronics, packaging, automotive, medical and textiles, due to its cost-effectiveness and superior performance. The molecular structure of PP consists of repeating propylene units, which enhances its mechanical strength and chemical stability. However, the hydrocarbon structure also makes PP highly flammable, requiring effective flame retardant treatment to ensure fire safety in most applications. Intumescent flame retardants (IFRs) such as ammonium polyphosphate, pentaerythritol and melamine play a key role in enhancing the flame retardancy of PP. However, traditional IFRs are inefficient and usually require high dosages, which also significantly reduces the mechanical properties of PP materials. The inherent bottlenecks of traditional intumescent flame retardants (IFRs), such as super hydrophilicity, reduced toughness and limited efficiency, also limit their application. In view of this, the development of flame retardants with high flame retardancy is crucial to meet the safety and functional requirements of various applications.

[0003] In addition, due to the presence of methyl groups in the side chains, polypropylene materials themselves are easily susceptible to discoloration, cracking, and powdering under the action of light and heat. Therefore, it is particularly necessary to improve the light aging performance of polypropylene materials. Based on the above background, it is necessary to provide a new modified polypropylene composition to accelerate its application in various complex scenarios. Summary of the invention

[0004] In order to overcome the deficiencies of the prior art, one of the objects of the present invention is to provide a modified polypropylene composition having excellent flame retardancy, light aging resistance and mechanical properties.

[0005] A second object of the present invention is to provide a method for preparing a modified polypropylene composition with simple steps.

[0006] One of the purposes of the present invention is achieved by the following technical solution: A modified polypropylene composition comprises the following raw materials by weight: 68-88 parts of polypropylene, 5-15 parts of toughening agent, 5-10 parts of flame retardant, 1-5 parts of compatibilizer, 0.2-0.5 parts of modified molybdenum disulfide, 0.2-0.5 parts of antioxidant and 0.1-0.5 parts of processing aid.

[0007] Preferably, the preparation process of the flame retardant is as follows: Add 1,10-phenanthroline-5-amine and triethylamine to tetrahydrofuran, then add a tetrahydrofuran solution of dichlorodiphenylsilane at 0-5°C. After rising to room temperature, react for 8-10 h. After the reaction is completed, purify to obtain the flame retardant.

[0008] Preferably, the molar ratio of 1,10-phenanthroline-5-amine, triethylamine, and dichlorodiphenylsilane is (3-6):(3-7):(1-3); the concentration of the tetrahydrofuran solution of dichlorodiphenylsilane is 0.3 mol / L.

[0009] Preferably, the preparation method of the modified molybdenum disulfide is as follows: (1) Disperse pretreated molybdenum disulfide in deionized water, then add mercaptoethylamine and mix evenly. After freeze-drying, obtain amino-functionalized molybdenum disulfide; (2) Add the amino-functionalized molybdenum disulfide obtained in step (1) to DMF, then add rhein, ethyl acetate, and p-toluenesulfonic acid for reaction. After the reaction is completed, purify to obtain modified molybdenum disulfide.

[0010] Preferably, in step (2), the dosage ratio of the amino-functionalized molybdenum disulfide, rhein, ethyl acetate, and p-toluenesulfonic acid is 0.5 g:(3-5) g:(5-8) mL:(0.03-0.05) g; the reaction temperature is 80-100°C, and the reaction time is 24-36 h.

[0011] Preferably, in step (1), the mass ratio of the pretreated molybdenum disulfide to mercaptoethylamine is 1:(0.006-0.008).

[0012] Preferably, the preparation process of the pretreated molybdenum disulfide is as follows: According to the dosage ratio of molybdenum disulfide powder to n-butyllithium of 1 g:(10-15) mL, add the molybdenum disulfide powder to n-butyllithium, stir and react for 3-4 d. After the reaction is completed, purify to obtain the pretreated molybdenum disulfide.

[0013] Preferably, the polypropylene has a melt mass flow rate of 2.0-5.0 g / 10 min at 230°C and a load of 2.16 kg, and the detection standard is ISO1133-1-2011; the toughening agent is an ethylene-butene copolymer olefin, and the melt flow mass rate is 1-1.3 g / 10 min at 230°C and a load of 2.16 kg.

[0014] Preferably, the compatibilizer is maleic anhydride grafted polypropylene, and the grafting rate of the maleic anhydride grafted polypropylene is 1-2 wt%; the processing aid is vinyl bisstearamide or calcium stearate; the antioxidant is antioxidant 1010 or antioxidant 1076.

[0015] The second object of the present invention is achieved by the following technical solution: The preparation method of the above-mentioned modified polypropylene composition comprises the following steps: Mix the raw materials evenly according to the weight ratio, and obtain the modified polypropylene composition through melt extrusion and granulation.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The modified polypropylene composition of the present invention has excellent flame retardancy, light aging resistance and mechanical properties.

[0017] 2. The modified polypropylene composition of the present invention contains components such as a flame retardant and modified molybdenum disulfide. The flame retardant is prepared from 1,10-phenanthroline-5-amine and dichlorodiphenylsilane. The silicon element, 1,10-phenanthroline group, amino group and benzene ring contained in the flame retardant play a synergistic flame retardant effect to efficiently inhibit combustion. Specifically, the silicon element contained in the flame retardant will generate a silicon dioxide protective layer during the combustion process to isolate oxygen and heat, thereby inhibiting combustion; the 1,10-phenanthroline group and the amino group will release non-combustible gases such as carbon dioxide and nitrogen to form a protective layer and dilute the concentration of combustible gases such as oxygen after being heated; and the benzene ring can promote the formation of a carbon layer to further isolate oxygen and heat and inhibit combustion. In addition, the introduction of the benzene ring can also enhance the rigidity of polypropylene, thereby improving the overall mechanical properties of the material. Modified molybdenum disulfide is prepared by reacting molybdenum disulfide with mercaptoethylamine to introduce an amino group, and the amino group-modified molybdenum disulfide is combined with the carboxyl group of rhein through an amidation reaction. Rhein contains an anthraquinone conjugate structure, which can absorb part of ultraviolet light and reduce the occurrence of photodegradation of polypropylene. Molybdenum disulfide has a shielding effect on ultraviolet light due to its unique layered structure. This inorganic-organic composite not only improves the stability and service life of rhein, but also can utilize the shielding and absorption effects of the two on ultraviolet light and cooperate with antioxidants to improve the light aging resistance of polypropylene.

[0018] 3. The preparation method of the modified polypropylene composition of the present invention has simple steps and is easy to be put into actual production. Specific Embodiments

[0019] The present invention will be further described below in conjunction with specific embodiments. It should be noted that, on the premise of no conflict, the following-described embodiments or technical features can be combined arbitrarily to form new embodiments. The specific conditions not specified in the examples are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are all conventional products obtained through commercial channels without special instructions.

[0020] For the polypropylene of the present invention, under the conditions of 230 °C and a load of 2.16 kg, the melt mass flow rate is 2.0 - 5.0 g / 10 min, and the detection standard is ISO1133 - 1 - 2011; the toughening agent is an ethylene - butene copolymer olefin, and under the conditions of 230 °C and a load of 2.16 kg, the melt flow mass rate is 1 - 1.3 g / 10 min; the compatibilizer is maleic anhydride grafted polypropylene, and the grafting rate of maleic anhydride grafted polypropylene is 1 - 2 wt%.

[0021] Example 1 This example provides a modified polypropylene composition. By weight, the modified polypropylene composition is composed of the following raw materials: 70 parts of polypropylene, 10 parts of ethylene - butene copolymer olefin, 6 parts of flame retardant, 4 parts of maleic anhydride grafted polypropylene, 0.3 part of modified molybdenum disulfide, 0.4 part of antioxidant 1010, and 0.2 part of vinyl bisstearamide.

[0022] The preparation process of the above - mentioned flame retardant is as follows: According to the molar ratio of 1,10 - phenanthroline - 5 - amine, triethylamine, and dichlorodiphenylsilane of 5:5:2, add 1,10 - phenanthroline - 5 - amine and triethylamine to tetrahydrofuran, and then add a 0.3 mol / L tetrahydrofuran solution of dichlorodiphenylsilane at 4 °C. After the dropping is completed, raise the temperature to room temperature and react for 9 h. After the reaction is completed, rotary evaporate and concentrate the reaction solution, and slurry and filter the residue with ethyl acetate / petroleum ether (v / v = 1:8) to obtain the flame retardant.

[0023] The NMR and mass spectrometry results of the flame retardant are as follows: 1 HNMR: (C 36 H 26 N6Si, 400 MHz, DMSO - d6 ) δ: 4.90 (s, 2H), 6.67 (s, 2H), 7.35 - 7.39 (m, 6H), 7.44 - 7.48 (m, 4H), 7.53 - 7.64 (m, 4H), 8.35 - 8.39 (m, 2H), 8.48 - 8.52 (m, 2H), 8.73 - 8.82 (m, 4H), MS (ESI) m / z = 570.20 [M]. The above results indicate that the target product is obtained.

[0024] The preparation method of the above - mentioned modified molybdenum disulfide is as follows: (1) According to the dosage ratio of molybdenum disulfide powder to n-butyllithium of 1 g: 12 mL, add molybdenum disulfide powder to n-butyllithium, stir and react for 3 d. After the reaction is completed, filter. The product is washed 3 times with n-hexane, then dried in an oven at 60 °C for 4 h, then added with deionized water and ultrasonically dispersed for 12 h, and freeze-dried at -50 °C for 24 h to obtain pretreated molybdenum disulfide. According to the mass ratio of pretreated molybdenum disulfide to mercaptoethylamine of 1 g: 7 mg, disperse the pretreated molybdenum disulfide in deionized water, then add mercaptoethylamine and ultrasonically mix evenly, and obtain amino-functionalized molybdenum disulfide after freeze-drying; (2) According to the dosage ratio of amino-functionalized molybdenum disulfide, DMF, rhein, ethyl acetate, and p-toluenesulfonic acid of 0.5 g: 25 mL: 4 g: 6 mL: 0.04 g, add the amino-functionalized molybdenum disulfide in step (1) to DMF, then add rhein, ethyl acetate, and p-toluenesulfonic acid, and react at 90 °C for 32 h. After the reaction is completed, centrifuge to obtain the product, and wash it with deionized water and acetone to obtain modified molybdenum disulfide.

[0025] This example also provides a preparation method of the above-mentioned modified polypropylene composition, which is specifically as follows: Mix the raw materials evenly according to the said weight ratio, and extrude and granulate them through a twin-screw extruder at a temperature of 200 °C and a screw speed of 500 rpm to obtain the modified polypropylene composition.

[0026] Example 2 This example provides a modified polypropylene composition. By weight, the modified polypropylene composition is composed of the following raw materials: 68 parts of polypropylene, 5 parts of ethylene-butene copolymer olefin, 5 parts of flame retardant, 1 part of maleic anhydride grafted polypropylene, 0.2 part of modified molybdenum disulfide, 0.2 part of antioxidant 1076, and 0.1 part of calcium stearate.

[0027] The preparation process of the above-mentioned flame retardant is as follows: According to the molar ratio of 1,10-phenanthroline-5-amine, triethylamine, and dichlorodiphenylsilane of 3: 3: 1, add 1,10-phenanthroline-5-amine and triethylamine to tetrahydrofuran, then add a 0.3 mol / L tetrahydrofuran solution of dichlorodiphenylsilane at 0 °C. After the dropping is completed, raise the temperature to room temperature and react for 10 h. After the reaction is completed, rotary evaporate and concentrate the reaction solution, and pulp and filter the residue with ethyl acetate / petroleum ether (v / v = 1: 8) to obtain the flame retardant. The nuclear magnetic resonance and mass spectrometry results are the same as those in Example 1.

[0028] The preparation method of the above-mentioned modified molybdenum disulfide is as follows: (1) According to the dosage ratio of molybdenum disulfide powder and n-butyl lithium of 1g:10mL, molybdenum disulfide powder was added to n-butyl lithium, and the reaction was stirred for 4 days. After the reaction was completed, the product was filtered and washed with n-hexane 3 times, and then dried in a 60°C oven for 4 hours, and then added with deionized water for ultrasonic dispersion for 12 hours, and freeze-dried at -50°C for 24 hours to obtain pretreated molybdenum disulfide. According to the mass ratio of pretreated molybdenum disulfide and mercaptoethylamine of 1g:6mg, the pretreated molybdenum disulfide was dispersed in deionized water, and then mercaptoethylamine was added for ultrasonic mixing, and then freeze-dried to obtain amination of molybdenum disulfide; (2) According to the amount ratio of amination molybdenum disulfide, DMF, rhein, ethyl acetate, and p-toluenesulfonic acid of 0.5 g: 25 mL: 3 g: 5 mL: 0.03 g, the amination molybdenum disulfide of step (1) is added to DMF, and then rhein, ethyl acetate, and p-toluenesulfonic acid are added, and the reaction is carried out at 80° C. for 36 h. After the reaction is completed, the product is obtained by centrifugation, and washed with deionized water and acetone to obtain modified molybdenum disulfide.

[0029] This embodiment also provides a method for preparing the modified polypropylene composition, which is as follows: The raw materials were mixed uniformly according to the weight ratio, melt-extruded and granulated through a twin-screw extruder at a temperature of 200° C. and a screw speed of 500 rpm to obtain the modified polypropylene composition.

[0030] Example 3 This embodiment provides a modified polypropylene composition, which is composed of the following raw materials in parts by weight: 88 parts of polypropylene, 15 parts of ethylene-butene copolymer olefin, 10 parts of flame retardant, 5 parts of maleic anhydride grafted polypropylene, 0.5 parts of modified molybdenum disulfide, 0.5 parts of antioxidant 1010, and 0.5 parts of vinyl bisstearamide.

[0031] The preparation process of the above flame retardant is as follows: According to the molar ratio of 1,10-phenanthroline-5-amino, triethylamine and dichlorodiphenylsilane of 6:7:3, 1,10-phenanthroline-5-amino and triethylamine were added to tetrahydrofuran, and then a 0.3 mol / L tetrahydrofuran solution of dichlorodiphenylsilane was added at 5°C. After the addition was completed, the temperature was raised to room temperature for reaction for 8 hours. After the reaction was completed, the reaction solution was concentrated by rotary evaporation, and the residue was slurried with ethyl acetate / petroleum ether (v / v=1:8) and filtered to obtain a flame retardant. The results of nuclear magnetic resonance and mass spectrometry were the same as those in Example 1.

[0032] The preparation method of the above-mentioned modified molybdenum disulfide is as follows: (1) According to the dosage ratio of molybdenum disulfide powder to n-butyllithium of 1 g:15 mL, add molybdenum disulfide powder to n-butyllithium, stir and react for 3 d. After the reaction is completed, filter. Wash the product with n-hexane, then dry it in an oven at 60 °C for 4 h, add deionized water and ultrasonically disperse for 12 h, and freeze-dry at -50 °C for 24 h to obtain pretreated molybdenum disulfide. According to the mass ratio of pretreated molybdenum disulfide to mercaptoethylamine of 1 g:8 mg, disperse the pretreated molybdenum disulfide in deionized water, then add mercaptoethylamine and ultrasonically mix evenly, and obtain amino-functionalized molybdenum disulfide through freeze-drying; (2) According to the dosage ratio of amino-functionalized molybdenum disulfide, DMF, rhein, ethyl acetate, and p-toluenesulfonic acid of 0.5 g:25 mL:5 g:8 mL:0.05 g, add the amino-functionalized molybdenum disulfide from step (1) to DMF, then add rhein, ethyl acetate, and p-toluenesulfonic acid, and react at 100 °C for 24 h. After the reaction is completed, centrifuge to obtain the product, and wash it with deionized water and acetone to obtain modified molybdenum disulfide.

[0033] This example also provides a preparation method of the above-mentioned modified polypropylene composition, which is as follows: According to the above weight ratio, mix the raw materials evenly, and melt-extrude and pelletize them through a twin-screw extruder at a temperature of 200 °C and a screw speed of 500 rpm to obtain the modified polypropylene composition.

[0034] Comparative Example 1 The difference between this comparative example and Example 1 is that: molybdenum disulfide is used to replace the modified molybdenum disulfide in Example 1, and the rest is the same as in Example 1.

[0035] Comparative Example 2 The difference between this comparative example and Example 1 is that: a mixture of ammonium polyphosphate, pentaerythritol, and melamine is used to replace the flame retardant in Example 1, and the mass ratio of ammonium polyphosphate, pentaerythritol, and melamine is 3:1:1, and the rest is the same as in Example 1.

[0036] Performance Test Perform relevant performance tests on the compositions prepared in Examples 1-3 and Comparative Examples 1-2. The test methods and standards are as described below, and the experimental results are shown in Table 1.

[0037] Tensile strength and elongation at break: Test according to the standard of GB / T 1040.1-2018; Flexural modulus: Test according to the standard of GB / T 9341-2008; Limiting oxygen index: Test according to the standard of GB / T 2406.2-2009; Aging resistance: Perform a 1000 h xenon lamp aging test according to the standard of GB / T 16422.2-2022 at a wavelength of 420 nm.

[0038] Table 1 As can be seen from the results in Table 1, the modified polypropylene composition prepared by the present invention has excellent flame retardancy, light aging resistance and mechanical properties.

[0039] Compared with Examples 1-3, the light aging resistance of the polypropylene composition prepared by using molybdenum disulfide to replace the modified molybdenum disulfide in Comparative Example 1 is significantly reduced. This shows that the modified molybdenum disulfide prepared by the present invention can improve the light aging resistance of the polypropylene composition. Through analysis, it is known that the present invention improves the dispersion of molybdenum disulfide in the matrix by reacting molybdenum disulfide with mercaptoethylamine to introduce amino groups. The amino-functionalized molybdenum disulfide combines with the carboxyl group of rhein through an amidation reaction, so that organic molecules are firmly grafted onto the surface of molybdenum disulfide to obtain modified molybdenum disulfide. Rhein contains an anthraquinone conjugate structure, which can absorb part of ultraviolet light and reduce the occurrence of polypropylene photodegradation. Molybdenum disulfide has a shielding effect on ultraviolet light due to its unique layered structure. This inorganic-organic composite not only improves the stability and service life of rhein, but also can utilize the shielding and absorption effects of the two on ultraviolet light, and cooperate with antioxidants to improve the light aging resistance of polypropylene.

[0040] Compared with Examples 1-3, the flame retardancy and mechanical properties of the polypropylene composition prepared by using a mixture of ammonium polyphosphate, pentaerythritol and melamine to replace the flame retardant in Example 1 in Comparative Example 2 are reduced. This shows that the flame retardant prepared by the present invention can improve the flame retardancy and mechanical properties of the polypropylene composition. Through analysis, it is known that the flame retardant prepared from 1,10-phenanthroline-5-amine and dichlorodiphenylsilane as raw materials by the present invention, and the silicon element, 1,10-phenanthroline group, amino group and benzene ring contained in the flame retardant play a synergistic flame retardant role and can efficiently inhibit combustion. Specifically, the silicon element contained in the flame retardant will form a silicon dioxide protective layer during the combustion process to isolate oxygen and heat, thereby inhibiting combustion; the 1,10-phenanthroline group and the amino group will release non-combustible gases such as carbon dioxide and nitrogen to form a protective layer after being heated, and dilute the concentration of combustible gases such as oxygen; and the benzene ring can promote the formation of a carbon layer to further isolate oxygen and heat and inhibit combustion. In addition, the introduction of the benzene ring can enhance the rigidity of polypropylene, thereby improving the overall mechanical properties of the material.

[0041] The above embodiments are only the preferred embodiments of the present invention, and the scope of protection of the present invention cannot be limited thereby. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention belong to the scope of protection required by the present invention.

Claims

1. A modified polypropylene composition, characterized in that, By weight parts, it includes the following raw materials: 68 - 88 parts of polypropylene, 5 - 15 parts of toughening agent, 5 - 10 parts of flame retardant, 1 - 5 parts of compatibilizer, 0.2 - 0.5 parts of modified molybdenum disulfide, 0.2 - 0.5 parts of antioxidant, and 0.1 - 0.5 parts of processing aid.

2. The modified polypropylene composition according to claim 1, characterized in that, The preparation process of the flame retardant is as follows: Add 1,10 - phenanthroline - 5 - amine and triethylamine into tetrahydrofuran, then add a tetrahydrofuran solution of dichlorodiphenylsilane at 0 - 5 °C, raise the temperature to room temperature and react for 8 - 10 h. After the reaction is completed, purify to obtain the flame retardant.

3. The modified polypropylene composition according to claim 2, wherein The molar ratio of 1,10 - phenanthroline - 5 - amine, triethylamine, and dichlorodiphenylsilane is (3 - 6):(3 - 7):(1 - 3); the concentration of the tetrahydrofuran solution of dichlorodiphenylsilane is 0.3 mol / L.

4. The modified polypropylene composition according to claim 1, wherein The preparation method of the modified molybdenum disulfide is as follows: (1) Disperse pretreated molybdenum disulfide in deionized water, then add mercaptoethylamine and mix evenly. After freeze - drying, obtain amino - modified molybdenum disulfide; (2) Add the amino - modified molybdenum disulfide obtained in step (1) to DMF, then add rhein, ethyl acetate, and p - toluenesulfonic acid for reaction. After the reaction is completed, purify to obtain modified molybdenum disulfide.

5. The modified polypropylene composition according to claim 4, wherein In step (2), the dosage ratio of amino - modified molybdenum disulfide, rhein, ethyl acetate, and p - toluenesulfonic acid is 0.5 g:(3 - 5) g:(5 - 8) mL:(0.03 - 0.05) g; the reaction temperature is 80 - 100 °C, and the reaction time is 24 - 36 h.

6. The modified polypropylene composition according to claim 4, characterized in that, In step (1), the mass ratio of pretreated molybdenum disulfide to mercaptoethylamine is 1:(0.006 - 0.008).

7. The modified polypropylene composition according to claim 6, characterized in that, The preparation process of the pretreated molybdenum disulfide is as follows: According to the dosage ratio of molybdenum disulfide powder to n - butyllithium of 1 g:(10 - 15) mL, add molybdenum disulfide powder to n - butyllithium, stir and react for 3 - 4 d. After the reaction is completed, purify to obtain pretreated molybdenum disulfide.

8. The modified polypropylene composition according to claim 1, wherein The polypropylene has a melt mass - flow rate of 2.0 - 5.0 g / 10 min under the conditions of 230 °C and a load of 2.16 kg, and the detection standard is ISO1133 - 1 - 2011; the toughening agent is an ethylene - butene copolymer olefin, and has a melt flow mass rate of 1 - 1.3 g / 10 min under the conditions of 230 °C and a load of 2.16 kg.

9. The modified polypropylene composition according to claim 1, characterized in that, The compatibilizer is maleic anhydride - grafted polypropylene, and the grafting rate of the maleic anhydride - grafted polypropylene is 1 - 2 wt%; the processing aid is vinyl bisstearamide or calcium stearate; the antioxidant is antioxidant 1010 or antioxidant 1076.

10. A method for preparing the modified polypropylene composition according to any one of claims 1-9, characterized in that, It includes the following steps: According to the weight part ratio, mix the raw materials evenly, and through melt extrusion and granulation, obtain the modified polypropylene composition.

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