A precipitation-resistant high-strength halogen-free flame-retardant polypropylene material and its preparation method and application

Abstract

The present invention discloses a precipitation-resistant high-strength halogen-free flame-retardant polypropylene material, its preparation method, and application. The material comprises the following raw materials in parts by weight: 40-75 parts of polypropylene resin; 20-30 parts of a halogen-free flame retardant; 10-20 parts of a propylene-based elastomer; 2-6 parts of maleic anhydride-grafted chlorinated polypropylene; 2-6 parts of modified magnesium sulfate whiskers; 0.1-1 parts of a primary antioxidant; 0.1-1 parts of a secondary antioxidant; 0.1-0.5 parts of an anti-dripping agent; and 0.2-1 parts of a lubricant. The precipitation-resistant halogen-free flame-retardant polypropylene composite material provided by the present invention has excellent flame retardant and mechanical properties, is not easily precipitated in hot and humid environments, maintains a good appearance and flame retardant properties, and is suitable for new energy vehicles and electrical industries that have high comprehensive flame retardant requirements.

Description

Technical Field

[0001] The invention belongs to the field of polypropylene composite materials and preparation methods thereof, and particularly relates to a precipitation-resistant high-strength halogen-free flame-retardant polypropylene material and a preparation method thereof. Background Art

[0002] Polypropylene (PP) is widely used in home appliances, automobiles, electronics and other fields. However, PP has a low oxygen index and serious molten droplets during combustion, which cannot meet the use requirements in the field of live fire protection and requires flame retardant modification. There are two main types of flame retardant modification of polypropylene, halogen-containing flame retardant and halogen-free flame retardant. Intumescent halogen-free flame retardants have high flame retardant efficiency, low smoke emission, low toxicity, and are more environmentally friendly. They have gradually replaced bromine-antimony flame retardants to become the mainstream application in the industry. However, as a highly polar small molecule compound, the powder easily absorbs water and agglomerates, has poor compatibility with resins, and is unevenly dispersed, resulting in pitting on the sample surface. It is easy to migrate to the surface and precipitate in a hot and humid environment, affecting the appearance of the product and reducing the flame retardant grade.

[0003] CN110483898A uses lubricants and silicone oil to improve the hygroscopic agglomeration problem of piperazine pyrophosphate. It has good water resistance at room temperature, but the silicone oil has a low melting point and is easily softened again when heated, making the product less water-resistant in a hot and humid environment. In addition, the silicone oil coating treatment easily causes the powder to agglomerate after long-term storage. CN112795085A uses epoxy resin to modify pentabromobenzyl polyacrylate to increase the molecular weight and compatibility of the flame retardant, but it uses a halogen-containing flame retardant and is only applicable to homopolymer polypropylene, which limits the scope of application of this method. CN112679863A discloses the use of a low-melting-point ester polymer to encapsulate and disperse the flame retardant in a polypropylene matrix to inhibit the surface migration of the flame retardant. However, the ester polymer has poor compatibility with polypropylene, poor mechanical properties, and is prone to phase separation after long-term use.

[0004] Therefore, inhibiting the secondary aggregation of flame retardants, improving their dispersibility and compatibility in resins, and reducing the precipitation of flame retardants are issues that need to be urgently addressed in halogen-free flame retardant systems. Summary of the Invention

[0005] In response to the above-mentioned problems existing in the prior art, the purpose of the present invention is to provide a halogen-free flame-retardant polypropylene material and a preparation method having good flame retardant properties and mechanical properties and not easy to precipitate in a hot and humid environment. By adding maleic anhydride grafted chlorinated polypropylene, propylene-based elastomer and modified magnesium sulfate whiskers, the compatibility and dispersibility of the flame retardant in the resin are synergistically improved, the water absorption and surface precipitation of the flame retardant can be inhibited, and the mechanical strength of the material is improved. It is suitable for new energy vehicles and electrical industries with high comprehensive flame retardancy requirements.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] The present invention provides a precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material, comprising the following raw materials in parts by weight:

[0008] 40-75 parts of polypropylene resin, such as 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, preferably 50-65 parts;

[0009] 20-30 parts of halogen-free flame retardant, for example, 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, preferably 20-25 parts;

[0010] 10-20 parts of propylene-based elastomer, such as 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, preferably 10-15 parts;

[0011] Maleic anhydride grafted chlorinated polypropylene 2-6 parts, such as 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, preferably 2-4 parts;

[0012] 2-6 parts of modified magnesium sulfate whiskers, such as 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, preferably 2-4 parts;

[0013] 0.1-1 part of primary antioxidant, such as 0.1 part, 0.3 part, 0.5 part, 0.7 part, 1.0 part, preferably 0.2-0.5 part;

[0014] 0.1-1 part of secondary antioxidant, such as 0.1 part, 0.3 part, 0.5 part, 0.7 part, 1.0 part, preferably 0.2-0.5 part;

[0015] 0.1-0.5 parts of anti-dripping agent, such as 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, preferably 0.2-0.3 parts;

[0016] Lubricant 0.2-1 part, such as 0.2 part, 0.4 part, 0.6 part, 0.8 part, 1.0 part, preferably 0.3-0.6 part.

[0017] In some specific examples, the polypropylene resin is copolymerized polypropylene;

[0018] Preferably, the polypropylene resin has a melt index of 10-100 g / 10 min at 230° C. under a load of 2.16 kg, such as 10 g / 10 min, 30 g / 10 min, 50 g / 10 min, 70 g / 10 min, 90 g / 10 min, or 100 g / 10 min.

[0019] In some specific examples, the halogen-free flame retardant is a nitrogen-phosphorus system halogen-free flame retardant, preferably at least one of Chongqing Kejufu FR-1420 and Presaifu 110DM.

[0020] In some specific examples, the propylene-based elastomer has an ethylene content of 4-16 wt%, such as 4 wt%, 6 wt%, 8 wt%, 10 wt%, 12 wt%, 14 wt%, or 16 wt%;

[0021] Preferably, the propylene-based elastomer has a melt index of 3-20 g / 10 min at a load of 2.16 kg and 230° C., such as 3 g / 10 min, 5 g / 10 min, 10 g / 10 min, 15 g / 10 min, or 20 g / 10 min;

[0022] Preferably, the propylene-based elastomer is at least one of ExxonMobil 6202 and Dow 2400.

[0023] In some specific examples, the maleic anhydride grafted modified chlorinated polypropylene has a maleic anhydride grafting rate of 1-3 wt%, such as 1.0 wt%, 1.5 wt%, 2.0 wt%, 2.5 wt%, and 3.0 wt%, and a chlorine content of 20-35 wt%, such as 20 wt%, 22 wt%, 24 wt%, 26 wt%, 28 wt%, 30 wt%, 32 wt%, 34 wt%, and 35 wt%;

[0024] The maleic anhydride grafted chlorinated polypropylene (CPP-g-MAH) is a product disclosed in the prior art. The present invention has no particular requirements for its source and can be purchased commercially, such as Toyobo Hardlen CY-9124P, F-2P, etc., or can be prepared by any feasible method based on the prior art, for example, it can be prepared by referring to the method disclosed in "Synthesis and Performance Study of Chlorinated Polypropylene / Maleic Anhydride Grafts";

[0025] Preferably, the maleic anhydride grafted chlorinated polypropylene is prepared by grafting chlorinated polypropylene and maleic anhydride in the presence of an initiator. This grafting reaction is a conventional method in the art and is not particularly limited. Professionals and technicians in this field can make corresponding adjustments based on needs.

[0026] In some specific examples, the modified magnesium sulfate whiskers are needle-shaped, with a length of 10-60 μm, such as 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, and 60 μm, and an aspect ratio of 15-30, such as 15, 20, 25, and 30;

[0027] Preferably, the contact angle of the modified magnesium sulfate whisker is 100-140°, such as 100°, 110°, 120°, 130°, 140°;

[0028] Preferably, the modified magnesium sulfate whisker uses a modifier that is a phosphatide salt containing a double-long carbon chain structure, preferably a L-α-phosphatidic acid sodium salt series product, more preferably at least one of L-α-phosphatidic acid (egg) (sodium salt), L-α-phosphatidic acid (soybean) (sodium salt), and 1-stearoyl-2-oleoyl-SN-glycero-3-phosphate monosodium salt;

[0029] Preferably, the modified magnesium sulfate whisker is L-α-phosphatidic acid sodium salt modified magnesium sulfate whisker;

[0030] The modified magnesium sulfate whiskers are prepared by surface-modifying magnesium sulfate whiskers with a modifier. The surface modification method can be conventional in the art, for example, the method disclosed in "Study on Surface Modification of Basic Magnesium Sulfate Whiskers" can be used for preparation.

[0031] Preferably, the modified magnesium sulfate whisker preparation method comprises mixing a slurry of magnesium sulfate whiskers and water with an alkaline solution of a modifier, and reacting to produce the modified magnesium sulfate whiskers. The present invention does not particularly limit the specific operating parameters of the preparation process, and can be adjusted accordingly based on existing technology and needs.

[0032] Existing magnesium sulfate whiskers (i.e. basic magnesium sulfate whiskers MOSw) products have good flame retardant and mechanical properties and can be used for filling and modification of polypropylene. However, the surface free energy of MOSw is large, it is easy to agglomerate, it is unevenly dispersed in the matrix, the surface polarity is large, and its compatibility with non-polar PP is very poor. During the experiment, the researchers and developers of this application accidentally discovered that the use of phosphatidic acid salts containing a double long carbon chain structure, wherein the long carbon chain contains at least 13-19 carbon atoms, such as L-α-phosphatidic acid sodium salt series products, to surface modify MOSw can effectively solve the above problems. The organic phosphorus groups contained in the modifier can promote the carbonization of the polymer. After modification, it can not only improve the compatibility of the whiskers and thus improve the mechanical properties of the composite material, but also further enhance the flame retardant properties. At the same time, the double long carbon chains contained can improve the agglomeration phenomenon, especially the special structure of L-α-phosphatidic acid sodium salt containing two asymmetric long fatty acid chains, which is more conducive to the more uniform dispersion of the modified magnesium sulfate whiskers in the substrate.

[0033] In some specific examples, the anti-drip agent is polytetrafluoroethylene.

[0034] In some specific examples, the primary antioxidant is a hindered phenol antioxidant, preferably at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (1010) and octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (1076).

[0035] In some specific examples, the auxiliary antioxidant is a phosphite antioxidant, preferably at least one of tris[2,4-di-tert-butylphenyl]phosphite (168) and bis(2,4-di-tert-butylphenol)pentaerythritol diphosphite (626).

[0036] In some specific examples, the lubricant is an amide, preferably at least one of N,N'-ethylenebisstearamide and erucamide.

[0037] The present invention also provides a method for preparing the above-mentioned precipitation-resistant high-strength halogen-free flame-retardant polypropylene material, which is prepared by adding various raw materials into a twin-screw extruder and melt-extruding and granulating. This is a conventional method in the art and is not particularly limited. For example, an exemplary preparation method is as follows:

[0038] Preferably, the present invention provides a method for preparing the precipitation-resistant high-strength halogen-free flame-retardant polypropylene material, comprising the following steps:

[0039] Polypropylene resin, halogen-free flame retardant, propylene-based elastomer, maleic anhydride grafted chlorinated polypropylene, primary antioxidant, secondary antioxidant, anti-dripping agent and lubricant are mixed according to the formula ratio and fed into the main feeding port of a twin-screw extruder. At the same time, modified magnesium sulfate whiskers are fed into the side feeding port, followed by melt extrusion and granulation to obtain a precipitation-resistant high-strength halogen-free flame-retardant polypropylene material.

[0040] In some specific examples, the mixing speed is 500-1500 rpm, such as 500 rpm, 1000 rpm, 1500 rpm, and the mixing time is 3-5 min, such as 3 min, 4 min, 5 min;

[0041] Preferably, the mixing is performed using a high-speed mixer.

[0042] In some specific examples, in the melt extrusion process, the extruder temperature is set as follows: 120-160°C in zone 1, for example, 120°C, 140°C, and 160°C; 170-190°C in zones 2 and 3, for example, 170°C, 180°C, and 190°C; 180-200°C in zones 4 to 6, for example, 180°C, 190°C, and 200°C; 170-190°C in zones 7 and 8, for example, 170°C, 180°C, and 190°C; and the screw speed is 300-400 rpm, for example, 300 rpm, 350 rpm, and 400 rpm.

[0043] The above-mentioned precipitation-resistant high-strength halogen-free flame-retardant polypropylene material of the present invention or the precipitation-resistant high-strength halogen-free flame-retardant polypropylene material prepared by the above-mentioned method is suitable for the fields of automobiles, home appliances, electronic appliances, etc., especially for new energy vehicles and electrical fields.

[0044] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0045] 1. The modified magnesium sulfate whiskers used can promote the carbonization of the polymer, further enhancing the flame retardancy and improving the whisker compatibility, building a rigid skeleton in the matrix and improving the mechanical properties of the composite material. Furthermore, compared to commonly used monoalkyl phosphoric acid modifiers, the modifier used in the present invention, particularly L-α-phosphatidic acid sodium salt, has a unique structure containing two asymmetric long fatty acid chains, resulting in more uniform dispersion in the substrate.

[0046] 2. The propylene-based elastomer used has a higher viscosity and a lower melting point (approximately 100°C) than PP resin. It melts at high temperatures, encapsulating the small molecule flame retardant and then dispersing it into the polypropylene resin matrix, preventing it from migrating to the material surface. The propylene-based elastomer with an ethylene content of 4-16% has a certain toughening effect, while also preventing excessive ethylene content from accelerating melt dripping, damaging the char layer, and reducing the flame retardancy level.

[0047] 3. A small portion of the maleic anhydride-grafted chlorinated polypropylene participates in crystallization, while the uncrystallized portion remains outside the spherulite structure of the polypropylene material for a certain length, entangled with the polypropylene chain segments. At the same time, the strong polarity creates a certain interaction between the spherulites, improving compatibility with inorganic fillers and dispersion in the matrix.

[0048] The precipitation-resistant halogen-free flame-retardant polypropylene composite material provided by the present invention has a rigid skeleton constructed by modified magnesium sulfate whiskers in a matrix to enhance the rigidity of the material and the dispersibility of the flame retardant, a propylene-based elastomer to enhance the toughness of the material and ensure the stability of the flame retardant during processing, and the intermolecular force of maleic anhydride grafted chlorinated polypropylene to enhance the dispersibility of the flame retardant. Under the synergistic effect of the three, the material has excellent flame retardant properties and mechanical properties, is not easy to precipitate in a hot and humid environment, and the molded product can maintain good appearance and flame retardant properties. The material is suitable for new energy vehicles and electrical industries with high comprehensive requirements for flame retardancy. DETAILED DESCRIPTION

[0049] Below will be further introduced and shown in the specific embodiment within the scope of the present invention by specific examples.These examples are merely illustrative, rather than limiting the scope of the present invention, because as long as under the condition that does not deviate from its essence and scope, can carry out many changes to the present invention.

[0050] Unless otherwise specified, all formulation and testing conditions in the present invention occurred at 25°C, 50% RH.

[0051] The sources of the raw materials and reagents involved in the examples of the present invention are as follows. Unless otherwise specified, all others were purchased from commercial sources:

[0052] Polypropylene resin: Copolymer polypropylene EP548R, with a melt index of 28 g / 10 min at 2.16 kg load and 230 ° C, manufactured by Wanhua Chemical; Copolymer polypropylene EP648U, with a melt index of 60 g / 10 min at 2.16 kg load and 230 ° C, manufactured by CNOOC and Shell.

[0053] Halogen-free flame retardant: FR-1420 (piperazine pyrophosphate system halogen-free flame retardant), Chongqing Kejufu New Materials Co., Ltd.; 110DM, Presaifu Chemical Co., Ltd.

[0054] Propylene-based elastomer: 6202, 15% ethylene content, 20 g / 10 min melt index at 230°C under a 2.16 kg load, ExxonMobil;

[0055] Main antioxidant: Antioxidant 1010, Xinxiu Chemical (Yantai) Co., Ltd.

[0056] Secondary antioxidant: tris(2,4-di-tert-butylphenyl) phosphite (antioxidant 168), Xinxiu Chemical (Yantai) Co., Ltd.

[0057] Anti-dripping agent: polytetrafluoroethylene, Shandong Dongyue;

[0058] Lubricant: N,N'-ethylene bisstearamide (EB-FF), Kao, Japan;

[0059] L-α-Phosphatidic acid (egg) (sodium salt): Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0060] 1-stearoyl-2-oleoyl-SN-glycero-3-phosphate monosodium salt: Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0061] Maleic anhydride grafted chlorinated polypropylene: F-2P, HardlenCY-9124P, Toyobo, Japan;

[0062] Chlorinated polypropylene: AD-253, Sandow Chemical;

[0063] Maleic anhydride: Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0064] Magnesium sulfate whiskers: WS-3D, Kangru Technology;

[0065] Preparation method of modified magnesium sulfate whiskers: using sodium salt of L-α-phosphate as a modifier, and referring to the method disclosed in "Study on Surface Modification of Basic Magnesium Sulfate Whiskers";

[0066] Modified magnesium sulfate whiskers a (L-α-phosphatidic acid (egg) (sodium salt)): needle-shaped, 20-40 μm in length, aspect ratio of 15-25, contact angle of 137°;

[0067] Modified magnesium sulfate whisker b (1-stearoyl-2-oleoyl-SN-glycero-3-phosphate monosodium salt): needle-shaped, 20-40 μm in length, aspect ratio of 15-25, and contact angle of 135°.

[0068] The performance testing method used in the embodiments of the present invention is as follows:

[0069] Tensile properties test was carried out according to ISO 527-2-2012;

[0070] Bending performance test is carried out according to ISO 178-2019;

[0071] Notched impact strength test is carried out according to ISO 179-1 / 1eA-2019;

[0072] Oxygen index test is carried out according to ISO 4589-2;

[0073] Vertical burning rating test is conducted according to UL94-2022;

[0074] The wet heat storage test was carried out in accordance with GB / T2423.1-2008, with an ambient temperature of 85°C, a relative humidity of 85%, and a test time of 168 hours.

[0075] Example 1

[0076] The polypropylene resin, halogen-free flame retardant, propylene-based elastomer, maleic anhydride grafted chlorinated polypropylene, primary antioxidant, secondary antioxidant, anti-dripping agent, and lubricant were mixed according to the formula (unit / g) of Example 1 in Table 1, mixed and stirred for 5 minutes using a high-speed mixer at 700 rpm, and then fed into the main feeding port of a twin-screw extruder. At the same time, modified magnesium sulfate whiskers were fed into the side feeding port, and then melt-mixed. The extruder temperature was set as follows: 140° C. in zone 1, 180° C. in zones 2 and 3, 190° C. in zones 4 to 6, and 180° C. in zones 7 and 8. The screw speed was 400 rpm, and extrusion granulation was performed to obtain a high-strength halogen-free flame-retardant polypropylene material resistant to precipitation.

[0077] Examples 2-4

[0078] The precipitation-resistant high-strength halogen-free flame-retardant polypropylene materials in Examples 2-4 were prepared respectively according to the method basically the same as that in Example 1, except that the types and proportions of raw materials were adjusted according to Table 1 (unit / g), and other parameters and operating conditions remained unchanged.

[0079] Table 1 Example raw material information

[0080]

[0081] Comparative Example 1

[0082] The modified polypropylene material was prepared in a manner substantially the same as in Example 1, except that the maleic anhydride-grafted chlorinated polypropylene F-2P was not added.

[0083] Comparative Example 2

[0084] The modified polypropylene material was prepared in substantially the same manner as in Example 1, except that the maleic anhydride grafted chlorinated polypropylene F-2P was replaced with an equal amount of chlorinated polypropylene AD-253.

[0085] Comparative Example 3

[0086] The modified polypropylene material was prepared in substantially the same manner as in Example 1, with the only difference being that the maleic anhydride-grafted chlorinated polypropylene F-2P was replaced with an equal amount of maleic anhydride.

[0087] Comparative Example 4

[0088] A modified polypropylene material was prepared in substantially the same manner as in Example 1, except that the modified magnesium sulfate whisker a was not added.

[0089] Comparative Example 5

[0090] A modified polypropylene material was prepared in substantially the same manner as in Example 1, with the only difference being that the modified magnesium sulfate whiskers a were replaced with an equal amount of unmodified magnesium sulfate whiskers WS-3D.

[0091] Comparative Example 6

[0092] The modified magnesium sulfate whisker a is prepared by replacing an equal amount of octadecyl phosphate with L-α-phosphatidic acid (egg) (sodium salt) as the modifier of the modified magnesium sulfate whisker;

[0093] Then, the modified magnesium sulfate whiskers prepared in the comparative example were used to prepare a modified polypropylene material in substantially the same manner as in Example 1.

[0094] Comparative Example 7

[0095] The modified polypropylene material was prepared in a manner substantially the same as in Example 1, except that the propylene-based elastomer 6202 was not added.

[0096] Comparative Example 8

[0097] The modified polypropylene material was prepared in substantially the same manner as in Example 1, with the only difference being that the propylene-based elastomer 6202 was substituted for an equal amount of the ethylene-octene elastomer.

[0098] The modified polypropylene pellets prepared in the above examples and comparative examples were respectively injection molded into test strips and subjected to performance tests. The results are shown in Table 2.

[0099] Table 2 Performance test results of the products obtained from Examples 1-4 and Comparative Examples 1-8 As can be seen from Table 2, Examples 1-4 and Comparative Examples 1-8 significantly improve the oxygen index and flexural modulus of the material after adding maleic anhydride grafted chlorinated polypropylene and modified magnesium sulfate whiskers. After wet heat aging, there is essentially no surface precipitation, and the material maintains an excellent V0 flame retardant rating. Adding propylene-based elastomers results in unchanged material flame retardant properties, with significantly improved impact strength. The test results of Comparative Examples 1-3 and 4-6 show that without maleic anhydride grafted chlorinated polypropylene and modified magnesium sulfate whiskers, the mechanical properties and oxygen index of the material decrease, and the flame retardant properties decrease or become ineffective. The flame retardant content needs to be increased, and after aging, there is a significant white precipitate, further reducing the flame retardant properties. The test results of Comparative Examples 5-6 show that without propylene-based elastomers, although the material flame retardant rating is unaffected, the oxygen index and toughness both decrease. Replacing the material with ethylene-octene elastomers to improve toughness reduces the flame retardant rating.

[0100] The precipitation-resistant halogen-free flame-retardant polypropylene composite material provided by the present invention has excellent flame retardant properties and mechanical properties, can improve the problem that flame-retardant PP is easy to precipitate under high temperature and high humidity conditions, and is suitable for new energy vehicles and electrical industries with high comprehensive requirements for flame retardancy.

[0101] The above is a detailed introduction to the precipitation-resistant high-strength halogen-free flame-retardant polypropylene material and its preparation method provided by the present invention, and the principles and implementation methods of the present invention are explained using specific examples. Finally, it should be noted that the above is only a preferred implementation method of the present invention, and its description is relatively specific and detailed, and does not impose any other form of limitation on the present invention. For ordinary technicians in this technical field, without departing from the method of the present invention, they can also make several improvements, supplements and modifications, and these improvements, supplements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material, characterized in that: Including the following raw materials by weight: 40-75 parts of polypropylene resin; 20-30 parts of halogen-free flame retardant; 10-20 parts of propylene-based elastomer; 2-6 parts of maleic anhydride grafted chlorinated polypropylene; 2-6 parts of modified magnesium sulfate whiskers; Primary antioxidant 0.1-1 part; 0.1-1 part of auxiliary antioxidant; 0.1-0.5 parts of anti-dripping agent; 0.2-1 part of lubricant; The modifier used in the modified magnesium sulfate whisker is phosphatide containing a double long carbon chain structure, wherein the long carbon chain contains 13-19 carbon atoms.

2. The precipitation-resistant high-strength halogen-free flame-retardant polypropylene material according to claim 1, characterized in that: Including the following raw materials by weight: 50-65 parts of polypropylene resin; 20-25 parts of halogen-free flame retardant; 10-15 parts of propylene-based elastomer; 2-4 parts of maleic anhydride grafted chlorinated polypropylene; 2-4 parts of modified magnesium sulfate whiskers; 0.2-0.5 parts of primary antioxidant; 0.2-0.5 parts of auxiliary antioxidant; 0.2-0.3 parts of anti-dripping agent; 0.3-0.6 parts of lubricant.

3. The precipitation-resistant high-strength halogen-free flame-retardant polypropylene material according to claim 1, characterized in that: The polypropylene resin is copolymerized polypropylene.

4. The precipitation-resistant high-strength halogen-free flame-retardant polypropylene material according to claim 3, characterized in that: The polypropylene resin has a melt index of 10-100 g / 10 min at a load of 2.16 kg and a temperature of 230° C.

5. The precipitation-resistant high-strength halogen-free flame-retardant polypropylene material according to claim 1, characterized in that: The halogen-free flame retardant is a nitrogen-phosphorus system halogen-free flame retardant.

6. The precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material according to claim 5, characterized in that: The halogen-free flame retardant is at least one of Chongqing Kejufu FR-1420 and Pusaifu Phosphate Chemical Co., Ltd. 110DM.

7. The precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material according to claim 1, characterized in that: The ethylene content of the propylene-based elastomer is 4-16 wt %.

8. The precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material according to claim 7, characterized in that: The propylene-based elastomer has a melt index of 3-20 g / 10 min at a load of 2.16 kg and a temperature of 230° C.

9. The precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material according to claim 7, characterized in that: The propylene-based elastomer is at least one of ExxonMobil 6202 and Dow 2400.

10. The precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material according to claim 1, characterized in that: The maleic anhydride grafted chlorinated polypropylene has a maleic anhydride grafting rate of 1-3 wt % and a chlorine content of 20-35 wt %.

11. The precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material according to claim 1, characterized in that: The modified magnesium sulfate whiskers are needle-shaped, have a length of 10-60 μm, and an aspect ratio of 15-30.

12. The precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material according to claim 11, characterized in that: The contact angle of the modified magnesium sulfate whisker is 100-140°.

13. The precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material according to claim 11, characterized in that: The modified magnesium sulfate whisker adopts L-α-phosphatidic acid sodium salt as a modifier.

14. The precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material according to claim 13, characterized in that: The modifier is at least one of L-α-phosphatidic acid (egg) (sodium salt), L-α-phosphatidic acid (soybean) (sodium salt), and 1-stearoyl-2-oleoyl-SN-glycerol-3-phosphate monosodium salt.

15. The precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material according to claim 11, characterized in that: The modified magnesium sulfate whisker is L-α-phosphatidic acid sodium salt modified magnesium sulfate whisker.

16. The precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material according to claim 1, characterized in that: The anti-drip agent is polytetrafluoroethylene; and / or The primary antioxidant is a hindered phenol antioxidant; and / or The secondary antioxidant is a phosphite antioxidant; and / or The lubricant is amide.

17. The precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material according to claim 16, characterized in that: The primary antioxidant is at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and octadecylβ-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

18. The precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material according to claim 16, characterized in that: The auxiliary antioxidant is at least one of tris[2,4-di-tert-butylphenyl]phosphite and bis(2,4-di-tert-butylphenol)pentaerythritol diphosphite.

19. The precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material according to claim 16, characterized in that: The lubricant is at least one of N,N'-ethylenebisstearamide and erucamide.

20. A method for preparing the precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material according to any one of claims 1 to 19, characterized in that: The following steps are involved: Polypropylene resin, halogen-free flame retardant, propylene-based elastomer, maleic anhydride grafted chlorinated polypropylene, primary antioxidant, secondary antioxidant, anti-dripping agent and lubricant are mixed and fed into the main feeding port of a twin-screw extruder. At the same time, modified magnesium sulfate whiskers are fed into the side feeding port, followed by melt extrusion and granulation to obtain a precipitation-resistant high-strength halogen-free flame-retardant polypropylene material.

21. The preparation method according to claim 20, characterized in that The mixing speed is 500-1500 rpm and the mixing time is 3-5 min; and / or During the melt extrusion process, the extruder temperature is set as follows: 120-160°C in zone 1, 170-190°C in zones 2 and 3, 180-200°C in zones 4 to 6, and 170-190°C in zones 7 and 8. The screw speed is 300-400 rpm.

22. The preparation method according to claim 21, characterized in that The mixing is performed using a high-speed mixer.

23. Use of the precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material according to any one of claims 1 to 19 or the precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material prepared by the method according to any one of claims 20 to 22 in the fields of automobiles and home appliances.

24. Use of the precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material according to any one of claims 1 to 19 or the precipitation-resistant, high-strength, halogen-free, flame-retardant polypropylene material prepared by the method according to any one of claims 20 to 22 in the field of electronic appliances.

25. The use according to claim 23, characterized in that Applicable to the field of new energy vehicles.

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