A modified polypropylene composition and a process for its preparation

Abstract

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

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, 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. PP's molecular structure, composed of repeating propylene units, enhances its mechanical strength and chemical stability. However, this 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 typically require high dosages, which significantly degrades the mechanical properties of PP materials. Inherent bottlenecks of traditional IFRs, such as super-hydrophilicity, reduced toughness, and limited efficiency, also limit their application. Therefore, the development of flame retardants with high flame retardancy is crucial to meet the safety and functional requirements of various applications.

[0003] Furthermore, due to the presence of methyl groups on the side chains, polypropylene is susceptible to failures such as discoloration, cracking, and powdering under the influence of light and heat. Therefore, improving the light aging performance of polypropylene is particularly necessary. Against this backdrop, 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 objectives 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:

[0007] A modified polypropylene composition comprises the following raw materials, calculated by weight: 68-88 parts of polypropylene, 5-15 parts of a toughening agent, 5-10 parts of a flame retardant, 1-5 parts of a compatibilizer, 0.2-0.5 parts of modified molybdenum disulfide, 0.2-0.5 parts of an antioxidant, and 0.1-0.5 parts of a processing aid.

[0008] Preferably, the preparation process of the flame retardant is as follows:

[0009]

[0010] 1,10-phenanthroline-5-amino and triethylamine are added to tetrahydrofuran, and then a tetrahydrofuran solution of dichlorodiphenylsilane is added at 0-5° C., and the mixture is heated to room temperature and reacted for 8-10 hours. After the reaction is completed, the mixture is purified to obtain a flame retardant.

[0011] Preferably, the molar ratio of the 1,10-phenanthroline-5-amino group, triethylamine, and dichlorodiphenylsilane is (3-6): (3-7): (1-3); and the concentration of the tetrahydrofuran solution of dichlorodiphenylsilane is 0.3 mol / L.

[0012] Preferably, the preparation method of the modified molybdenum disulfide is as follows:

[0013] (1) Dispersing the pretreated molybdenum disulfide in deionized water, adding mercaptoethylamine and mixing evenly, and freeze-drying to obtain amino molybdenum disulfide;

[0014] (2) Add the amination-modified molybdenum disulfide of step (1) to DMF, and then add rhein, ethyl acetate, and p-toluenesulfonic acid to react. After the reaction is completed, purification is performed to obtain modified molybdenum disulfide.

[0015] Preferably, in step (2), the usage ratio of amination 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.

[0016] Preferably, the mass ratio of the pretreated molybdenum disulfide to mercaptoethylamine in step (1) is 1:(0.006-0.008).

[0017] Preferably, the preparation process of the pretreated molybdenum disulfide is as follows: according to the usage ratio of molybdenum disulfide powder and n-butyl lithium being 1 g: (10-15) mL, molybdenum disulfide powder is added to n-butyl lithium, stirred for reaction for 3-4 days, and purified after the reaction is completed to obtain pretreated molybdenum disulfide.

[0018] Preferably, the polypropylene has a melt flow rate of 2.0-5.0 g / 10 min at 230° C. and a load of 2.16 kg, and the test standard is ISO1133-1-2011; the toughening agent is an ethylene-butene copolymer olefin, and has a melt flow rate of 1-1.3 g / 10 min at 230° C. and a load of 2.16 kg.

[0019] Preferably, the compatibilizer is maleic anhydride grafted polypropylene, and the grafting rate of the maleic anhydride grafted polypropylene is 1-2wt%; the processing aid is vinyl bisstearamide or calcium stearate; and the antioxidant is antioxidant 1010 or antioxidant 1076.

[0020] The second object of the present invention is achieved by adopting the following technical solution:

[0021] The preparation method of the modified polypropylene composition comprises the following steps:

[0022] The raw materials are uniformly mixed according to the weight ratio, melt-extruded and granulated to obtain the modified polypropylene composition.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The modified polypropylene composition of the present invention has excellent flame retardancy, light aging resistance and mechanical properties.

[0025] 2. The modified polypropylene composition of the present invention contains a flame retardant, modified molybdenum disulfide, and other ingredients. The flame retardant is made from 1,10-phenanthroline-5-amino and dichlorodiphenylsilane. The silicon, 1,10-phenanthroline groups, amino groups, and benzene rings in the flame retardant work together to effectively suppress combustion. Specifically, the silicon in the flame retardant forms a protective silicon dioxide layer during combustion, isolating oxygen and heat, thereby suppressing combustion. Upon heating, the 1,10-phenanthroline groups and amino groups release non-combustible gases such as carbon dioxide and nitrogen, forming a protective layer and diluting the concentration of combustible gases such as oxygen. The benzene rings promote the formation of a char layer, further isolating oxygen and heat, and suppressing combustion. Furthermore, the introduction of benzene rings enhances the rigidity of the polypropylene, thereby improving the overall mechanical properties of the material. Modified molybdenum disulfide is produced by reacting molybdenum disulfide with mercaptoethylamine to introduce amino groups. The aminated molybdenum disulfide is then combined with the carboxyl groups of rhein through an amidation reaction. Rhein contains an anthraquinone conjugated structure, which can absorb some 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 complex not only improves the stability and service life of rhein, but also utilizes the shielding and absorption effects of the two on ultraviolet light, synergistically with antioxidants, to improve the light aging resistance of polypropylene.

[0026] 3. The preparation method of the modified polypropylene composition of the present invention has simple steps and is easy to put into actual production. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with specific embodiments. It should be noted that, under the premise of no conflict, the various embodiments described below or the various technical features can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. All reagents or instruments used, unless otherwise specified, are conventional products obtained through commercial channels.

[0028] The polypropylene of the present invention 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 testing 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; the compatibilizer is maleic anhydride grafted polypropylene, and the grafting rate of the maleic anhydride grafted polypropylene is 1-2 wt%.

[0029] Example 1

[0030] This embodiment provides a modified polypropylene composition, which is composed of the following raw materials in parts by weight:

[0031] 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 parts of modified molybdenum disulfide, 0.4 parts of antioxidant 1010, and 0.2 parts of vinyl bisstearamide.

[0032] The preparation process of the above flame retardant is as follows:

[0033]

[0034] According to the molar ratio of 1,10-phenanthroline-5-amino, triethylamine and dichlorodiphenylsilane of 5:5:2, 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 4°C. After the addition was completed, the temperature was raised to room temperature and the reaction was carried out for 9 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.

[0035] The NMR and mass spectrometry results of the flame retardant are as follows:

[0036] 1 HNMR: (C 36 H 26 N6Si, 400MHz, 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 indicated that the target product was obtained.

[0037] The preparation method of the modified molybdenum disulfide is as follows:

[0038] (1) According to the amount ratio of molybdenum disulfide powder, n-butyllithium 1g:12mL, the molybdenum disulfide powder is added to n-butyllithium, stirred for 3d, after the reaction is completed, the product is washed with n-hexane for 3 times, then dried in the oven at 60℃ for 4h, then added with deionized water and ultrasonic dispersed for 12h, -50℃ freeze-dried for 24h, then the pretreated molybdenum disulfide is obtained. According to the mass ratio of pretreated molybdenum disulfide, mercaptoethylamine 1g:7mg, the pretreated molybdenum disulfide is dispersed in deionized water, then added with mercaptoethylamine and ultrasonic mixed uniformly, freeze-dried, then the aminated molybdenum disulfide is obtained.

[0039] (2) According to the amount ratio of aminated molybdenum disulfide, DMF, rheum emodin, ethyl acetate, p-toluenesulfonic acid 0.5g:25mL:4g:6mL:0.04g, the aminated molybdenum disulfide of step (1) is added to DMF, then added with rheum emodin, ethyl acetate, p-toluenesulfonic acid, 90℃ reaction for 32h, after the reaction is completed, the product is obtained by centrifugation, washed with deionized water, acetone, then the modified molybdenum disulfide is obtained.

[0040] The embodiment also provides a preparation method of the modified polypropylene composition, and the preparation method is specifically as follows:

[0041] According to the weight ratio, the raw materials are uniformly mixed, melt-extruded and pelletized by a twin-screw extruder with a temperature of 200℃ and a screw rotation speed of 500rpm, so that the modified polypropylene composition is obtained.

[0042] Example 2

[0043] The embodiment provides a modified polypropylene composition, and the modified polypropylene composition is composed of the following raw materials in parts by weight:

[0044] Polypropylene 68 parts, ethylene-butene copolymer olefin 5 parts, flame retardant 5 parts, maleic anhydride grafted polypropylene 1 part, modified molybdenum disulfide 0.2 part, antioxidant 1076 0.2 part, calcium stearate 0.1 part.

[0045] The preparation process of the flame retardant is as follows:

[0046] According to the molar ratio of 1,10-phenanthroline-5-amino, triethylamine, dichlorodiphenylsilane 3:3:1, 1,10-phenanthroline-5-amino and triethylamine are added to tetrahydrofuran, then 0.3mol / L dichlorodiphenylsilane tetrahydrofuran solution is added at 0℃, after the dropwise addition is completed, the reaction is carried out at room temperature for 10h, after the reaction is completed, the reaction solution is concentrated by rotary evaporation, the residue is slurried with ethyl acetate / petroleum ether (v / v=1:8), filtered, then the flame retardant is obtained, and the nuclear magnetic resonance and mass spectrum results are the same as those of example 1.

[0047] The preparation method of the modified molybdenum disulfide is as follows:

[0048] (1) Add molybdenum disulfide powder to n-butyl lithium at a ratio of 1 g:10 mL, stir and react for 4 days, filter after the reaction, wash the product with n-hexane three times, dry in a 60°C oven for 4 hours, add deionized water for ultrasonic dispersion for 12 hours, and freeze-dry at -50°C for 24 hours to obtain pretreated molybdenum disulfide. Disperse the pretreated molybdenum disulfide in deionized water at a mass ratio of 1 g:6 mg, add mercaptoethylamine for ultrasonic mixing, and freeze-dry to obtain amino molybdenum disulfide.

[0049] (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) was added to DMF, and then rhein, ethyl acetate, and p-toluenesulfonic acid were added, and the mixture was reacted at 80° C. for 36 h. After the reaction was completed, the product was centrifuged to obtain the product, which was washed with deionized water and acetone to obtain modified molybdenum disulfide.

[0050] This embodiment also provides a method for preparing the modified polypropylene composition, which is as follows:

[0051] 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.

[0052] Example 3

[0053] This embodiment provides a modified polypropylene composition, which is composed of the following raw materials in parts by weight:

[0054] 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.

[0055] The preparation process of the above flame retardant is as follows:

[0056] 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 complete, the temperature was raised to room temperature and reacted 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 nuclear magnetic resonance and mass spectrometry results were the same as those in Example 1.

[0057] The preparation method of the modified molybdenum disulfide is as follows:

[0058] (1) Add molybdenum disulfide powder to n-butyl lithium at a ratio of 1g:15mL, stir and react for 3 days, filter after the reaction, wash the product with n-hexane, dry it in a 60℃ oven for 4h, add deionized water for ultrasonic dispersion for 12h, freeze-dry it at -50℃ for 24h to obtain pretreated molybdenum disulfide. Disperse the pretreated molybdenum disulfide in deionized water at a mass ratio of 1g:8mg, add mercaptoethylamine for ultrasonic mixing, and freeze-dry to obtain amino molybdenum disulfide.

[0059] (2) According to the amount ratio of amination molybdenum disulfide, DMF, rhein, ethyl acetate, and p-toluenesulfonic acid of 0.5 g: 25 mL: 5 g: 8 mL: 0.05 g, the amination molybdenum disulfide of step (1) was added to DMF, and then rhein, ethyl acetate, and p-toluenesulfonic acid were added, and the mixture was reacted at 100 ° C for 24 h. After the reaction was completed, the product was centrifuged to obtain the product, which was washed with deionized water and acetone to obtain modified molybdenum disulfide.

[0060] This embodiment also provides a method for preparing the modified polypropylene composition, which is as follows:

[0061] 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.

[0062] Comparative Example 1

[0063] 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 Example 1.

[0064] Comparative Example 2

[0065] 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, the mass ratio of ammonium polyphosphate, pentaerythritol and melamine is 3:1:1, and the rest is the same as Example 1.

[0066] Performance Testing

[0067] The compositions prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to relevant performance tests. The test methods and standards are as follows. The experimental results are shown in Table 1.

[0068] Tensile strength and elongation at break: tested in accordance with GB / T 1040.1-2018 standard;

[0069] Flexural modulus: tested in accordance with GB / T 9341-2008 standard;

[0070] Limiting oxygen index: tested in accordance with GB / T 2406.2-2009 standard;

[0071] Aging resistance: Xenon lamp aging test was carried out for 1000h at a wavelength of 420nm in accordance with GB / T 16422.2-2022.

[0072] Table 1

[0073]

[0074] It can be seen from the results in Table 1 that the modified polypropylene composition prepared in the present invention has excellent flame retardancy, light aging resistance and mechanical properties.

[0075] Compared to Examples 1-3, the light aging resistance of the polypropylene composition prepared in Comparative Example 1 using molybdenum disulfide instead of modified molybdenum disulfide was significantly reduced. This demonstrates that the modified molybdenum disulfide prepared in the present invention can improve the light aging resistance of the polypropylene composition. Analysis shows that the present invention improves the dispersibility of molybdenum disulfide in the matrix by reacting molybdenum disulfide with mercaptoethylamine to introduce amino groups. The aminated molybdenum disulfide combines with the carboxyl groups of rhein through an amidation reaction, resulting in the organic molecule being firmly grafted onto the surface of the molybdenum disulfide to obtain the modified molybdenum disulfide. Rhein contains an anthraquinone conjugated structure that can absorb some ultraviolet light, reducing the occurrence of polypropylene photodegradation. Molybdenum disulfide, due to its unique layered structure, has a shielding effect against ultraviolet light. This inorganic-organic composite not only improves the stability and service life of rhein, but also utilizes the shielding and absorption effects of both for ultraviolet light, synergistically acting with antioxidants to improve the light aging resistance of polypropylene.

[0076] Compared with Examples 1-3, the flame retardancy and mechanical properties of the polypropylene composition obtained by replacing the flame retardant of Example 1 with a mixture of ammonium polyphosphate, pentaerythritol and melamine 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. Analysis shows that the flame retardant prepared by the present invention using 1,10-phenanthroline-5-amino and dichlorodiphenylsilane as raw materials, the silicon element, 1,10-phenanthroline group, amino group and benzene ring contained in the flame retardant play a synergistic flame retardant effect and can effectively 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; 1,10-phenanthroline group and amino group will release non-combustible gases such as carbon dioxide and nitrogen after heating to form a protective layer and dilute the concentration of combustible gases such as oxygen; and benzene ring can promote the formation of a carbon layer, further isolate oxygen and heat, and inhibit combustion. In addition, the introduction of benzene ring can also enhance the rigidity of polypropylene, thereby improving the overall mechanical properties of the material.

[0077] The above embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and replacements made by technicians in this field on the basis of the present invention fall within the scope of protection required by the present invention.

Claims

1. A modified polypropylene composition, characterized in that The following raw materials are included 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. The preparation process of the flame retardant is as follows: 1,10-phenanthroline-5-amino and triethylamine are added to tetrahydrofuran, and then a tetrahydrofuran solution of dichlorodiphenylsilane is added at 0-5° C., and the mixture is heated to room temperature and reacted for 8-10 hours. After the reaction is completed, the mixture is purified to obtain a flame retardant.

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

3. The modified polypropylene composition according to claim 1, characterized in that The preparation method of the modified molybdenum disulfide is as follows: (1) Dispersing the pretreated molybdenum disulfide in deionized water, adding mercaptoethylamine and mixing evenly, and freeze-drying to obtain amino molybdenum disulfide; (2) Add the amination-modified molybdenum disulfide obtained in step (1) to DMF, and then add rhein, ethyl acetate, and p-toluenesulfonic acid to carry out the reaction. After the reaction is completed, the modified molybdenum disulfide is purified to obtain the modified molybdenum disulfide.

4. The modified polypropylene composition according to claim 3, characterized in that In step (2), the ratio of the amount of aminated 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.

5. The modified polypropylene composition according to claim 3, characterized in that The mass ratio of the pretreated molybdenum disulfide and mercaptoethylamine in step (1) is 1: (0.006-0.008).

6. The modified polypropylene composition according to claim 5, characterized in that The preparation process of the pretreated molybdenum disulfide is as follows: according to the usage ratio of molybdenum disulfide powder to n-butyl lithium being 1 g: (10-15) mL, the molybdenum disulfide powder is added to n-butyl lithium, the mixture is stirred and reacted for 3-4 days, and after the reaction is completed, the pretreated molybdenum disulfide is purified to obtain the pretreated molybdenum disulfide.

7. The modified polypropylene composition according to claim 1, characterized in that The polypropylene has a melt flow rate of 2.0-5.0 g / 10 min at 230° C. and a load of 2.16 kg, and the testing standard is ISO1133-1-2011; the toughening agent is an ethylene-butene copolymer olefin, and has a melt flow rate of 1-1.3 g / 10 min at 230° C. and a load of 2.16 kg.

8. 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 1-2wt%; the processing aid is vinyl bisstearamide or calcium stearate; and the antioxidant is antioxidant 1010 or antioxidant 1076.

9. The method for preparing the modified polypropylene composition according to any one of claims 1 to 8, characterized in that: The steps include: The raw materials are uniformly mixed according to the weight ratio, melt-extruded and granulated to obtain the modified polypropylene composition.

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