A long-lasting antistatic polypropylene composition and a method for its preparation

Abstract

This invention discloses a long-lasting antistatic polypropylene composition and its preparation method. The composition, based on 100 parts by weight of polypropylene resin, comprises 2.0-6.0 parts of a nonionic antistatic agent, 0.15-1.50 parts of a halogen-free ionic liquid, 1.0-5.0 parts of maleic anhydride-grafted polypropylene, 0.05-1.50 parts of a migration-regulating agent, 0.10-0.60 parts of an antioxidant, and 0.05-0.80 parts of a lubrication processing aid. The nonionic antistatic agent and the halogen-free ionic liquid form a synergistic conductive and slow-release migration system. The maleic anhydride-grafted polypropylene improves the compatibility of the antistatic system with the polypropylene matrix, and the migration-regulating agent forms an adsorption confinement and interfacial dispersion effect on the antistatic components. This invention also discloses a preparation method involving drying, premixing, melt extrusion, cooling pelletizing, and homogenization. The resulting composition maintains good tensile strength, notched impact strength, and processing fluidity while ensuring long-term stable surface resistivity.

Description

Technical Field

[0001] This invention belongs to the field of polymer material modification technology, specifically, it relates to a long-lasting antistatic polypropylene composition and its preparation method. Background Technology

[0002] Polypropylene (PP) has advantages such as low density, good chemical resistance, easy processing, and low cost, making it widely used in packaging, automobiles, electronics, daily necessities, and industrial turnover products. However, PP has low molecular chain polarity, resulting in poor electrical conductivity and a surface resistivity typically reaching [insert value here]. During friction, peeling, conveying, stacking, or injection molding demolding, static electricity can easily accumulate. This accumulation can cause dust attraction, surface contamination, and processing adhesion. In scenarios such as electronic component packaging, flammable dust environments, and precision instrument housings, it can also cause component damage, discharge interference, and even safety hazards.

[0003] To reduce the surface resistivity of polypropylene products, existing technologies typically employ modification by adding antistatic agents or conductive fillers. Conductive fillers such as conductive carbon black, carbon nanotubes, and graphene can form relatively stable conductive networks; however, these fillers are generally dark in color, difficult to disperse, and tend to increase system viscosity and affect product appearance, making them unsuitable for light-colored, transparent, or food-contact packaging products. While metal powders and metal fibers offer significant conductivity, their high density and cost can negatively impact the toughness and processing stability of polypropylene.

[0004] Internally added antistatic agents are a common method for antistatic modification of polypropylene. These antistatic agents are melt-mixed with the resin during processing, and after molding, they adsorb moisture from the air through a certain degree of surface migration, forming a weakly conductive layer, thereby reducing the surface resistance of the product.

[0005] Existing internal antistatic agents mainly include cationic, anionic, and nonionic antistatic agents. Cationic antistatic agents have a faster antistatic effect, but they have problems with thermal stability, irritation, corrosiveness, or compatibility in some applications; anionic antistatic agents are significantly dependent on environmental humidity and have limited compatibility with polypropylene matrix; nonionic antistatic agents, such as polyethylene glycol, glycerol fatty acid esters, and polyoxyethylene ethers, are widely used due to their relatively good compatibility, low odor, and low corrosiveness.

[0006] However, in practical production applications, the use of nonionic antistatic agents alone still has the following shortcomings: Nonionic antistatic agents rely on migration to the surface of materials to exert their effects. Initially, the surface resistance may be reduced, but after long-term use, wiping, washing, temperature and humidity cycling, and high-temperature aging, the antistatic agent is easily consumed or lost from the surface of the product, resulting in an increase in surface resistance and insufficient antistatic long-term effect. To obtain a lower surface resistance, it is often necessary to increase the amount of nonionic antistatic agent added. However, a higher amount of added agent will make the material surface sticky and cause whitening, and reduce tensile strength, impact strength and thermal deformation stability. The significant polarity difference between the antistatic agent and the polypropylene matrix can easily lead to the formation of localized enrichment zones during melt blending and subsequent molding, resulting in fluctuations in product performance. Some long-lasting antistatic systems improve their antistatic properties by introducing halogenated, phosphorus-containing, or fluorine-containing components. However, these components face limitations in terms of environmental regulatory compliance, odor control, and high-end applications. In view of this, the present invention is proposed. Summary of the Invention

[0007] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows: A long-lasting antistatic polypropylene composition, measured as 100 parts by weight of polypropylene resin, comprises the following components: 100 parts polypropylene resin; 2.0-6.0 parts nonionic antistatic agent; 0.15-1.50 parts halogen-free ionic liquid; 1.0-5.0 parts maleic anhydride-grafted polypropylene; 0.05-1.50 parts migration control agent; 0.10-0.60 parts antioxidant; 0.05-0.80 parts lubrication processing aid. The nonionic antistatic agent contains polyether segments and aliphatic hydrocarbon segments, and the halogen-free ionic liquid is an organic salt ionic liquid that is free of halogens, phosphorus, and perfluoroalkyl structures. The mass ratio of the nonionic antistatic agent to the halogen-free ionic liquid is 4:1-25:1. The maleic anhydride-grafted polypropylene is used to form an interfacial compatibility layer between the polypropylene resin, the nonionic antistatic agent, and the halogen-free ionic liquid. The migration control aid is used to adsorb and confine the nonionic antistatic agent and the halogen-free ionic liquid, thereby delaying the precipitation and loss of the antistatic components.

[0008] In a preferred embodiment of the present invention, the polypropylene resin is one or a mixture of at least two of homopolymer polypropylene, random copolymer polypropylene, and block copolymer polypropylene; the melt flow rate of the polypropylene resin at 230°C and 2.16 kg is 5-60 g / 10 min.

[0009] In a preferred embodiment of the present invention, the nonionic antistatic agent is selected from one or a mixture of at least two of polyethylene glycol fatty acid esters, polyoxyethylene fatty alcohol ethers, polyether-modified glycerol fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and polyether amide antistatic agents; the number average molecular weight of the nonionic antistatic agent is 800-6000, the hydroxyl value is 20-150 mgKOH / g, and the HLB value is 8-16.

[0010] In a preferred embodiment of the present invention, the halogen-free ionic liquid is selected from one or a mixture of at least two of 1-ethyl-3-methylimidazolium ethyl sulfate, 1-butyl-3-methylimidazolium methanesulfonate, choline acetate, choline lactate, and triethylmethylammonium methyl sulfate; the halogen-free ionic liquid has a conductivity of not less than 0.5 mS / cm at 25°C, a thermal decomposition temperature of not less than 220°C, and a moisture content of not more than 0.50 wt%.

[0011] In a preferred embodiment of the present invention, the maleic anhydride grafting rate of the maleic anhydride-grafted polypropylene is 0.3-1.8 wt%, and the melt mass flow rate at 190°C and 2.16 kg is 20-150 g / 10 min; the mass ratio of the maleic anhydride-grafted polypropylene to the halogen-free ionic liquid is 2:1-20:1.

[0012] In a preferred embodiment of the present invention, the migration regulating agent is one or a mixture of at least two of the following: hydrophilic modified nano-silica, silane coupling agent treated nano-silica, layered silicate, montmorillonite, and mesoporous silicate; the average particle size of the migration regulating agent is 10-800 nm, and the specific surface area is 50-600 m² / g.

[0013] In a preferred embodiment of the present invention, the invention further includes 0.5-8.0 parts of a polyolefin elastomer, wherein the polyolefin elastomer is one or a mixture of at least two of ethylene-octene copolymer, ethylene-butene copolymer, and propylene-based elastomer; and 0.05-0.50 parts of a nucleating agent, wherein the nucleating agent is one or a mixture of at least two of sorbitol-based nucleating agents, organophosphate nucleating agents, and aromatic carboxylate nucleating agents.

[0014] In a preferred embodiment of the present invention, the antioxidant comprises a hindered phenolic primary antioxidant and a phosphite secondary antioxidant, wherein the mass ratio of the hindered phenolic primary antioxidant to the phosphite secondary antioxidant is 1:0.5-1:3; the lubricating processing aid is selected from one or a mixture of at least two of ethylene bis-stearamide, calcium stearate, polyethylene wax, polypropylene wax and silicone powder.

[0015] As a preferred embodiment of the present invention, the present invention also discloses a method for preparing a long-lasting antistatic polypropylene composition, applied to the long-lasting antistatic polypropylene composition according to any one of claims 1-8, characterized in that it includes the following steps: Step S1: Pre-disperse the nonionic antistatic agent, halogen-free ionic liquid and migration control agent to obtain an antistatic pre-dispersion system; Step S2: Add polypropylene resin, maleic anhydride-grafted polypropylene, antistatic pre-dispersion system, antioxidant, and lubricating processing aid to a high-speed mixer and mix to obtain a premix. Step S3: Add the premixed material to a twin-screw extruder for melt blending and extrusion to obtain extruded strips; Step S4: Cool, dry and pelletize the extruded strip, and homogenize the resulting pellets to obtain a long-lasting antistatic polypropylene composition.

[0016] In a preferred embodiment of the present invention, in step S1, the pre-dispersion temperature is 40-80℃ and the pre-dispersion time is 5-30 min; in step S2, the mixing speed is 600-1000 rpm and the mixing time is 3-8 min; in step S3, the feed section temperature of the twin-screw extruder is 160-180℃, the melting section temperature is 180-200℃, the homogenization section temperature is 185-205℃, the die head temperature is 190-210℃, the screw speed is 200-400 r / min, and the vacuum degree is -0.02--0.08 MPa.

[0017] Compared with the prior art, the present invention has the following advantages: This invention employs a binary synergistic system of a nonionic antistatic agent and a halogen-free ionic liquid. The nonionic antistatic agent provides continuous surface migration and hygroscopic conductivity, while the halogen-free ionic liquid provides ionic conductivity and interacts with the nonionic antistatic agent, thereby reducing the initial surface resistivity of the material and suppressing the rapid recovery of surface resistivity during long-term use.

[0018] This invention controls the mass ratio of nonionic antistatic agent to halogen-free ionic liquid to be 4:1-25:1, so that the antistatic system has sufficient conductivity continuity, while avoiding the material's moisture absorption, precipitation, odor, or mechanical property degradation caused by excessive ionic liquid.

[0019] This invention introduces maleic anhydride-grafted polypropylene as an interfacial compatibility component, which forms a stable transition phase between the polypropylene matrix and the antistatic system, reduces the aggregation and local enrichment of antistatic agents, and maintains tensile strength, notched impact strength and elongation at break while reducing surface resistance.

[0020] This invention introduces a migration regulation aid to form an adsorption confinement and slow-release migration effect on antistatic components, thereby improving the problems of traditional nonionic antistatic agents that are prone to rapid precipitation, performance degradation after wiping, and resistance rebound after long-term storage.

[0021] The formulation of this invention does not use conductive carbon black and metal powder, or fluorine- or phosphorus-containing components as necessary antistatic components. The resulting products have better color adaptability, lower odor, and wider environmental compatibility.

[0022] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0023] In the attached diagram: Figure 1 This relates to a long-lasting antistatic polypropylene composition and its preparation method; Figure 2 This invention relates to a long-lasting antistatic polypropylene composition and its preparation method. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention.

[0025] like Figure 1 As shown, a long-lasting antistatic polypropylene composition, measured as 100 parts by weight of polypropylene resin, comprises the following components: 100 parts of polypropylene resin; 2.0-6.0 parts of nonionic antistatic agent; 0.15-1.50 parts of halogen-free ionic liquid; Maleic anhydride-grafted polypropylene 1.0-5.0 parts; Migration regulation agent 0.05-1.50 parts; Antioxidant 0.10-0.60 parts; Lubricating processing aid 0.05-0.80 parts.

[0026] Furthermore, it also includes 0.5-8.0 parts of polyolefin elastomer and / or 0.05-0.50 parts of nucleating agent.

[0027] The polypropylene resin can be one or a mixture of at least two of homopolymer polypropylene, random copolymer polypropylene, and block copolymer polypropylene. For injection molded products, a polypropylene resin with a melt flow rate of 8-35 g / 10 min is preferred; for extruded sheets or plates, a polypropylene resin with a melt flow rate of 3-15 g / 10 min is preferred.

[0028] Nonionic antistatic agents contain polyether segments and aliphatic hydrocarbon segments. The polyether segments provide hydrophilicity and hygroscopic conductivity, while the aliphatic hydrocarbon segments improve compatibility with polypropylene resin, preventing complete phase separation within the resin. The nonionic antistatic agent is preferably one or a mixture of at least two of the following: polyethylene glycol fatty acid esters, polyoxyethylene fatty alcohol ethers, polyether-modified glycerol fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and polyether amide antistatic agents.

[0029] Halogen-free ionic liquids are organic salt ionic liquids that are free of halogens, phosphorus, and perfluoroalkyl structures. Halogen-free ionic liquids can improve ion migration in the system, reduce the surface resistance of materials in low-humidity environments, and form hydrogen bonds, dipoles, or ion-dipole interactions with the polyether segments in nonionic antistatic agents, thereby slowing down the rapid precipitation of the nonionic antistatic agent. The halogen-free ionic liquid is preferably one or a mixture of at least two of the following: 1-ethyl-3-methylimidazolium ethyl sulfate, 1-butyl-3-methylimidazolium methanesulfonate, choline acetate, choline lactate, and triethylmethylammonium methyl sulfate.

[0030] Maleic anhydride-grafted polypropylene is used to form a transition phase between a nonpolar polypropylene matrix and a polar antistatic system. The polypropylene segments in maleic anhydride-grafted polypropylene exhibit good compatibility with the polypropylene matrix. The polar groups of maleic anhydride can interact with the polar groups on the surface of nonionic antistatic agents, halogen-free ionic liquids, or migration-regulating agents, thereby reducing the aggregation of the antistatic system and improving the retention of mechanical properties.

[0031] The migration control agent is an inorganic micro / nano material with surface hydroxyl, siloxy, or layered confined structures, preferably one or a mixture of at least two of the following: hydrophilic modified nano-silica, silane coupling agent-treated nano-silica, layered silicates, montmorillonite, and mesoporous silicates. The migration control agent can adsorb a portion of nonionic antistatic agents and halogen-free ionic liquids, allowing the antistatic component to be uniformly dispersed in the polypropylene matrix in the form of micro-regions, reducing the sudden precipitation of antistatic agents on the product surface while maintaining long-term slow-release migration.

[0032] Antioxidants include hindered phenolic primary antioxidants and phosphite secondary antioxidants. The hindered phenolic primary antioxidant can be one or both of antioxidants 1010 and 1076; the phosphite secondary antioxidant can be antioxidant 168. The combined use of primary and secondary antioxidants can reduce the thermo-oxidative degradation of polypropylene during melt extrusion.

[0033] Lubricating processing aids can be one or a mixture of at least two of ethylene bis-stearamide, calcium stearate, polyethylene wax, polypropylene wax, and silicone powder. These aids are used to reduce friction between the melt and equipment, improve extrusion stability, and enhance product surface quality.

[0034] Furthermore, the present invention also provides a method for preparing the above-mentioned long-lasting antistatic polypropylene composition, comprising the following steps: S1. Pre-dispersion: Stir the nonionic antistatic agent, halogen-free ionic liquid and migration control agent at 40-80℃ for 5-30 min to obtain the antistatic pre-dispersion system; S2. Premix: Add polypropylene resin, maleic anhydride-grafted polypropylene, antistatic pre-dispersion system, antioxidant and lubricating processing aid to a high-speed mixer and mix for 3-8 minutes at a mixing speed of 600-1000 rpm to obtain a premix. S3. Melt extrusion: Add the premixed material into a twin-screw extruder, control the temperature of the feeding section to 160-180℃, the temperature of the melting section to 180-200℃, the temperature of the homogenization section to 185-205℃, the temperature of the die head to 190-210℃, and the screw speed to 200-400 r / min for melt blending extrusion. S4. Cooling and pelletizing: The extruded strip is cooled with water, dried, and then pelletized. S5. Homogenization: The obtained granules are fed into a homogenization chamber for mixing and homogenization to obtain a long-lasting antistatic polypropylene composition.

[0035] Furthermore, the nonionic antistatic agent and halogen-free ionic liquid are dried at 60-90℃ for 2-4 hours before use; the polypropylene resin and maleic anhydride-grafted polypropylene are dried at 80-100℃ for 2-4 hours; the twin-screw extruder has an aspect ratio of 36:1-48:1, and the extrusion process is set with weak vacuum exhaust, with a vacuum degree of -0.02--0.08MPa.

[0036] Experimental example: Polypropylene resin PP-1: Block copolymer polypropylene, melt flow rate of 18 g / 10 min at 230℃ and 2.16 kg; Polypropylene resin PP-2: Random copolymer polypropylene, melt flow rate of 25 g / 10 min at 230℃ and 2.16 kg; Nonionic antistatic agent A: Polyether modified glycerol fatty acid ester, number average molecular weight about 2200, HLB value about 12; Nonionic antistatic agent B: Polyoxyethylene fatty alcohol ether, number average molecular weight about 1800, HLB value about 10; IL-1, a halogen-free ionic liquid: 1-ethyl-3-methylimidazolium ethyl sulfate; IL-2, a halogen-free ionic liquid: choline acetate; Compatibilizer: Maleic anhydride-grafted polypropylene, with a maleic anhydride grafting rate of approximately 1.0 wt% and a melt flow rate of approximately 80 g / 10 min at 190°C and 2.16 kg. Migration control aid M-1: hydrophilic modified nano-silica with an average particle size of about 40 nm and a specific surface area of ​​about 200 m² / g; Migration control aid M-2: Organically modified montmorillonite with an average lamellar thickness of less than 100 nm; Polyolefin elastomer: ethylene-octene copolymer; Antioxidant: Antioxidant 1010 and Antioxidant 168 are compounded in a mass ratio of 1:1; Lubricating processing aid: Ethylene bis-stearamide.

[0037] The above-mentioned raw materials are for illustrative purposes only. Those skilled in the art can select similar raw materials with comparable performance within the scope of this invention.

[0038] The testing method is as follows: Step 1, Surface Resistance: Inject the granules into 100mm×100mm×2mm test pieces, acclimate them at 23℃ and 50%RH for 48 hours, and then test the surface resistance according to the method specified in GB / T1410.

[0039] Step 2, Long-term antistatic performance: After placing the test piece at 23℃ and 50%RH for 12 months, test the surface resistance; take another test piece and age it at 60℃ and 90%RH for 168h, then equilibrate it at 23℃ and 50%RH for 24h before testing the surface resistance.

[0040] Step 3, Antistatic performance after wiping: Use a lint-free cloth soaked in deionized water to wipe the surface of the test piece 50 times, and test the surface resistance after drying at room temperature for 24 hours.

[0041] Step 4, Tensile strength: Test according to GB / T1040.2, tensile speed 50mm / min.

[0042] Step 5, Notched Impact Strength: Tested according to GB / T1843, using the notched impact method of a simply supported beam.

[0043] Step 6, Elongation at break: Tested according to GB / T1040.2.

[0044] Step 7, Melt mass flow rate: Tested according to GB / T3682.1, test conditions are 230℃ and 2.16kg.

[0045] The formulations for Examples 1-5 are shown in Table 1.

[0046] Table 1. Formulation composition of Examples 1-5

[0047] The preparation method of Example 1 is as follows: Nonionic antistatic agents A, IL-1, and M-1 were added to a pre-dispersion reactor and stirred at 60°C for 15 min to obtain an antistatic pre-dispersion system. PP-1, maleic anhydride-grafted polypropylene, polyolefin elastomer, nucleating agent, antioxidant, lubricating processing aid, and the aforementioned antistatic pre-dispersion system were added to a high-speed mixer and mixed at 800 rpm for 5 min to obtain a premix. The premix was then melt-extruded in a twin-screw extruder with a length-to-diameter ratio of 40:1. The temperatures of each zone were 165°C, 175°C, 185°C, 195°C, 200°C, and 205°C, respectively, with a die head temperature of 205°C, a screw speed of 300 rpm, and a vacuum degree of -0.05 MPa. The extruded strip was water-cooled, dried, and pelletized before being homogenized in a homogenization chamber for 30 min to obtain a long-lasting antistatic polypropylene composition.

[0048] Examples 2-5 were prepared in basically the same way as Example 1, except that the formulations were adjusted according to Table 1. Specifically, the screw speed in Example 3 was 260 r / min, the screw speed in Example 4 was 320 r / min, and in Example 5, M-2 was used instead of M-1 and the pre-dispersion time was extended to 20 min.

[0049] The formulations of Comparative Examples 1-5 are shown in Table 2. The preparation methods of each comparative example are basically the same as those of Example 1, with the only difference being the formulation composition.

[0050] Table 2. Formulation composition of Comparative Examples 1-5

[0051] Among them, Comparative Example 1 did not add halogen-free ionic liquid; Comparative Example 2 did not add maleic anhydride-grafted polypropylene; Comparative Example 3 used a higher amount of a single nonionic antistatic agent, without adding halogen-free ionic liquid, maleic anhydride-grafted polypropylene, or migration control aid; Comparative Example 4 did not add migration control aid; Comparative Example 5 did not add nonionic antistatic agent, but only added halogen-free ionic liquid.

[0052] The performance test results of Examples 1-5 and Comparative Examples 1-5 are shown in Table 3.

[0053]

[0054]

[0055] As can be seen from Table 3, the initial surface resistance of the compositions obtained in Examples 1-5 is all within the range of... Quantity or close to The quantity, after 12 months of storage, humid heat aging, and wiping, still maintains its quality. The magnitude indicates that the formulation of this invention has good long-lasting antistatic properties. Meanwhile, the tensile strength of Examples 1-5 is not less than 28 MPa, the notched impact strength is not less than 15 kJ·m⁻², and the elongation at break is greater than 300%, indicating that the composition maintains good mechanical properties while achieving antistatic properties.

[0056] Comparative Example 1, which did not contain halogen-free ionic liquid, showed a lower initial surface resistivity compared to ordinary polypropylene. However, after 12 months, after damp heat aging, and after wiping, the surface resistivity increased significantly, indicating that the long-term effectiveness of using nonionic antistatic agents alone was insufficient.

[0057] Comparative Example 2, without the addition of maleic anhydride-grafted polypropylene, showed acceptable initial antistatic properties, but its surface resistivity increased over time, and its tensile strength, notched impact strength, and elongation at break decreased significantly. This indicates that the antistatic system is unstable in polypropylene when interfacial compatibility components are lacking, which can easily lead to local enrichment and deterioration of mechanical properties.

[0058] Comparative Example 3 used a high amount of a single nonionic antistatic agent, which initially had a low surface resistance. However, after long-term storage, humid heat aging, and wiping, the surface resistance increased significantly, and the mechanical properties decreased significantly. This indicates that simply increasing the amount of nonionic antistatic agent cannot solve the problem of long-term antistatic effect. Instead, it increases the risk of precipitation and performance loss.

[0059] Comparative Example 4, without the addition of migration-regulating agents, had a low initial surface resistance, but its surface resistance increased after prolonged storage and wiping. The magnitude indicates that migration-regulating agents play an important role in delaying the rapid loss of antistatic components and improving long-term stability.

[0060] Comparative Example 5, which did not contain a nonionic antistatic agent but only a halogen-free ionic liquid, showed unsatisfactory initial and long-term antistatic performance. This indicates that halogen-free ionic liquid alone is difficult to form a stable and effective surface antistatic structure in polypropylene systems and must be used in conjunction with a nonionic antistatic agent to form a synergistic system.

[0061] The above results demonstrate that this invention does not simply involve the superposition of antistatic agents, but rather addresses the issues of antistatic durability, compatibility, and retention of mechanical properties of polypropylene through the synergistic effect of nonionic antistatic agents, halogen-free ionic liquids, maleic anhydride-grafted polypropylene, and migration-regulating agents. Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A long-lasting antistatic polypropylene composition, characterized in that, Based on 100 parts by weight of polypropylene resin, it comprises the following components: 100 parts polypropylene resin; 2.0-6.0 parts nonionic antistatic agent; 0.15-1.50 parts halogen-free ionic liquid; 1.0-5.0 parts maleic anhydride-grafted polypropylene; 0.05-1.50 parts migration control agent; 0.10-0.60 parts antioxidant; 0.05-0.80 parts lubrication processing aid. The nonionic antistatic agent contains polyether segments and aliphatic hydrocarbon segments, and the halogen-free ionic liquid is an organic salt ionic liquid that is free of halogens, phosphorus, and perfluoroalkyl structures. The mass ratio of the nonionic antistatic agent to the halogen-free ionic liquid is 4:1-25:

1. The maleic anhydride-grafted polypropylene is used to form an interfacial compatibility layer between the polypropylene resin, the nonionic antistatic agent, and the halogen-free ionic liquid. The migration control aid is used to adsorb and confine the nonionic antistatic agent and the halogen-free ionic liquid, thereby delaying the precipitation and loss of the antistatic components.

2. The long-lasting antistatic polypropylene composition according to claim 1, characterized in that, The polypropylene resin is one or a mixture of at least two of homopolymer polypropylene, random copolymer polypropylene, and block copolymer polypropylene; the melt flow rate of the polypropylene resin at 230°C and 2.16 kg is 5-60 g / 10 min.

3. The long-lasting antistatic polypropylene composition according to claim 1, characterized in that, The nonionic antistatic agent is selected from one or a mixture of at least two of polyethylene glycol fatty acid esters, polyoxyethylene fatty alcohol ethers, polyether-modified glycerol fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and polyether amide antistatic agents; the number average molecular weight of the nonionic antistatic agent is 800-6000, the hydroxyl value is 20-150 mgKOH / g, and the HLB value is 8-16.

4. The long-lasting antistatic polypropylene composition according to claim 1, characterized in that, The halogen-free ionic liquid is selected from one or a mixture of at least two of 1-ethyl-3-methylimidazolium ethyl sulfate, 1-butyl-3-methylimidazolium methanesulfonate, choline acetate, choline lactate, and triethylmethylammonium methyl sulfate; the halogen-free ionic liquid has a conductivity of not less than 0.5 mS / cm at 25°C, a thermal decomposition temperature of not less than 220°C, and a moisture content of not more than 0.50 wt%.

5. The long-lasting antistatic polypropylene composition according to claim 1, characterized in that, The maleic anhydride-grafted polypropylene has a maleic anhydride grafting rate of 0.3-1.8 wt% and a melt mass flow rate of 20-150 g / 10 min at 190 °C and 2.16 kg. The mass ratio of the maleic anhydride-grafted polypropylene to the halogen-free ionic liquid is 2:1-20:

1.

6. The long-lasting antistatic polypropylene composition according to claim 1, characterized in that, The migration control aid is one or a mixture of at least two of the following: hydrophilic modified nano-silica, silane coupling agent treated nano-silica, layered silicate, montmorillonite, and mesoporous silicate; the average particle size of the migration control aid is 10-800 nm, and the specific surface area is 50-600 m² / g.

7. The long-lasting antistatic polypropylene composition according to claim 1, characterized in that, It also includes 0.5-8.0 parts of a polyolefin elastomer, wherein the polyolefin elastomer is one or a mixture of at least two of ethylene-octene copolymer, ethylene-butene copolymer and propylene-based elastomer; and 0.05-0.50 parts of a nucleating agent, wherein the nucleating agent is one or a mixture of at least two of sorbitol nucleating agents, organophosphate nucleating agents and aromatic carboxylate nucleating agents.

8. The long-lasting antistatic polypropylene composition according to claim 1, characterized in that, The antioxidant includes hindered phenolic primary antioxidant and phosphite secondary antioxidant, wherein the mass ratio of hindered phenolic primary antioxidant to phosphite secondary antioxidant is 1:0.5-1:3; the lubricating processing aid is selected from one or a mixture of at least two of ethylene bis-stearamide, calcium stearate, polyethylene wax, polypropylene wax and silicone powder.

9. A method for preparing a long-lasting antistatic polypropylene composition, applied to the long-lasting antistatic polypropylene composition according to any one of claims 1-8, characterized in that, Includes the following steps: Step S1: Pre-disperse the nonionic antistatic agent, halogen-free ionic liquid and migration control agent to obtain an antistatic pre-dispersion system; Step S2: Add polypropylene resin, maleic anhydride-grafted polypropylene, antistatic pre-dispersion system, antioxidant, and lubricating processing aid to a high-speed mixer and mix to obtain a premix. Step S3: Add the premixed material to a twin-screw extruder for melt blending and extrusion to obtain extruded strips; Step S4: Cool, dry and pelletize the extruded strip, and homogenize the resulting pellets to obtain a long-lasting antistatic polypropylene composition.

10. The method for preparing a long-lasting antistatic polypropylene composition according to claim 9, characterized in that, In step S1, the pre-dispersion temperature is 40-80℃ and the pre-dispersion time is 5-30 min; in step S2, the mixing speed is 600-1000 rpm and the mixing time is 3-8 min; in step S3, the feed section temperature of the twin-screw extruder is 160-180℃, the melting section temperature is 180-200℃, the homogenization section temperature is 185-205℃, the die head temperature is 190-210℃, the screw speed is 200-400 r / min, and the vacuum degree is -0.02--0.08 MPa.

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