Antistatic plastic packaging film and preparation method thereof

Abstract

The invention discloses an antistatic plastic packaging film and a preparation method thereof, belongs to the technical field of packaging film processing, and aims to solve the technical problem that the light transmittance, antistatic property, toughness and aging resistance of a plastic packaging film need to be further improved in the prior art. The preparation method specifically comprises the following steps: mixing TEMPO-based activated polysiloxane, N-methylimidazole and a toluene solution, raising the temperature of a reaction system to 78-82 DEG C, carrying out heat preservation reaction for 20-22 hours, and carrying out post-treatment to obtain the supported polysiloxane. According to the invention, the PP plastic matrix is enhanced after the PP mixture is prepared by carrying out block bonding on the PP-g-MAH through the supported polysiloxane and the 6-cyclopropyl-1, 2, 4-triazine-3-amine, so that the light transmittance and the antistatic property of the plastic packaging film are effectively improved, and the toughness and the aging resistance of the plastic packaging film are also improved.

Description

Technical Field

[0001] This invention relates to the field of packaging film processing technology, specifically to an antistatic plastic packaging film and its preparation method. Background Technology

[0002] Plastic packaging films are widely used in many industries such as food, pharmaceuticals, electronics, and daily chemicals due to their significant advantages such as being lightweight, transparent, flexible, and low-cost. In the food packaging field, they can effectively isolate air, moisture, and odors, extend the shelf life of food, and maintain its freshness and taste. In the pharmaceutical industry, they can be used for single-dose packaging of medicines to ensure the hygiene and safety of medicines. In electronic product packaging, they can provide dustproof, moisture-proof, and mechanical damage-proof protection for delicate electronic components.

[0003] In existing technologies, plastic packaging films are mainly made of polyolefin-based thermoplastics such as polypropylene and polyethylene. These films have high surface resistivity and are prone to generating and accumulating static charges during use and storage. Adding antistatic agents to plastic packaging films is the most widely used antistatic method. Polymer permanent antistatic agents conduct static electricity by blending with the plastic matrix to form conductive channels. Although their antistatic effect is relatively long-lasting, large amounts can affect the physical properties of the plastic packaging film, such as tensile strength and transparency. Inorganic filler-type antistatic agents, such as carbon black and metal powders, although having good conductivity, will significantly change the color and appearance of the plastic packaging film after addition. Furthermore, plastic packaging films will discolor when exposed to ultraviolet radiation during use, causing them to yellow or change color, reducing their light transmittance and further limiting their application in packaging fields where high light transmittance is required.

[0004] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide an antistatic plastic packaging film and its preparation method, which solves the technical problem that the light transmittance, antistatic properties, toughness and aging resistance of plastic packaging films need to be further improved in the prior art.

[0006] The objective of this invention can be achieved through the following technical solution: a method for preparing an antistatic plastic packaging film, comprising the following steps: S1. Mix TEMPO-activated polysiloxane, N-methylimidazol and toluene solution, raise the temperature of the reaction system to 78-82℃, keep the reaction at this temperature for 20-22h, and then perform post-treatment to obtain supported polysiloxane. The synthesis reaction equation for supported polysiloxanes is as follows: S2. Add PP-g-MAH, supported polysiloxane, and 6-cyclopropyl-1,2,4-triazine-3-amine to a mixer at a temperature of 170-190℃, mix for 10-15 minutes, cool down and discharge to obtain silane PP mixture; S3. Add the silane PP mixture, PP and auxiliary additives to a twin-screw extruder, melt mix for 2-3 minutes and then extrude into a blown film extruder to obtain a plastic packaging film with a thickness of 30-50μm.

[0007] Further, in step S1, the ratio of TEMPO-modified polysiloxane, N-methylimidazole, and toluene solution is 7g:2g:30mL, and the toluene solution is composed of toluene and N,N-dimethylformamide in a volume ratio of 7:2. The post-treatment includes: after the reaction is complete, the temperature of the reaction system is lowered to room temperature, purified water is added to the reaction system, the mixture is stirred and dispersed for 20-30 minutes, the mixture is allowed to stand and separated, the organic phase is washed three times with purified water and then transferred to a rotary evaporator with a water bath temperature of 80-90℃ to remove low-boiling substances under reduced pressure to obtain the supported polysiloxane; in step S2, the weight ratio of PP-g-MAH, supported polysiloxane, and 6-cyclopropyl-1,2,4-triazine-3-amine is 50:18-22:3-5.

[0008] Further, in step S3, the weight ratio of the silane PP mixture, PP, and auxiliary additives is 50:50-60:2-3. The auxiliary additives are composed of lubricant, dispersant, plasticizer, and antioxidant in a weight ratio of 2:3:5:2. The lubricant is one or more of oleamide, hexamethylenetetramine, and octylamide. The dispersant is one or more of stearates. The plasticizer is phthalate. The antioxidant is antioxidant 168 or antioxidant 100. The temperatures of the four temperature zones of the twin-screw extruder from the feed end to the discharge end are 225°C, 230°C, 230°C, and 235°C, respectively. The blowing temperature of the blown film extruder is 220-230°C.

[0009] Furthermore, the preparation method of TEMPO-based activated polysiloxane is as follows: TEMPO-modified polysiloxane, 3-butene-1-amine, toluene and mixed catalyst are mixed, the temperature of the reaction system is raised to 100-110℃, the reaction is kept at the temperature for 8-10h, and then post-processed to obtain TEMPO-based activated polysiloxane.

[0010] The synthesis reaction equation for TEMPO-based activated polysiloxanes is as follows: Furthermore, the ratio of the TEMPO-modified polysiloxane, 3-butene-1-amine, toluene, and mixed catalyst is 15g:1.8-2.2g:60mL:0.02g. The catalyst is composed of chloroplatinic acid and triphenylphosphine in a weight ratio of 3:1. The post-treatment includes: after the reaction is complete, maintaining the temperature of the reaction system at 100-110℃, removing low-boiling substances by vacuum distillation, and obtaining TEMPO-based activated polysiloxane.

[0011] Furthermore, the preparation method of TEMPO-modified polysiloxane is as follows: amino-modified polysiloxane, toluene and 4-epoxypropyloxy-TEMPO free radical are mixed, the reaction system temperature is raised to 70-80℃, and the reaction is maintained at this temperature for 3-5 hours. An inert gas is introduced into the reaction system, and under the inert gas atmosphere, the reaction system temperature is lowered to -5~-10℃. Chloroacetyl chloride is added dropwise to the reaction system. After the addition is complete, the reaction system temperature is raised to room temperature, and the reaction is maintained at this temperature for 6-8 hours. After post-treatment, TEMPO-modified polysiloxane is obtained.

[0012] The synthesis reaction equation for TEMPO-modified polysiloxane is as follows: In the formula, Furthermore, the ratio of amino-modified polysiloxane, toluene, 4-epoxypropyloxy-TEMPO radical, and chloroacetyl chloride is 15g:100mL:2.4-2.8g:7g. The post-treatment includes: after the reaction is complete, adding 10wt% sodium bicarbonate solution to the reaction system, stirring for 20-30min, allowing it to stand and separate the liquids, washing the organic phase three times with purified water, and then transferring it to a rotary evaporator with a water bath temperature of 80-90℃ to remove low-boiling substances under reduced pressure to obtain TEMPO-modified polysiloxane.

[0013] Furthermore, the preparation method of amino-modified polysiloxane is as follows: octamethylcyclotetrasiloxane, aminopropylmethyldimethoxysilane and catalyst are mixed, the temperature of the reaction system is raised to 85-95℃, the reaction is maintained at this temperature for 50-60 min, an end-capping agent is added to the reaction system, the reaction is maintained at this temperature for 100-120 min, and then post-treatment is performed to obtain amino-modified polysiloxane.

[0014] The synthesis reaction equation for amino-modified polysiloxanes is as follows: Furthermore, the ratio of octamethylcyclotetrasiloxane, aminopropylmethyldimethoxysilane, catalyst, and end-capping agent is 15g:6-7g:3-4mL:2.2-2.6g, the end-capping agent is 1,1,3,3-tetramethyldisiloxane, the catalyst is 60-70wt% sulfuric acid, and the post-treatment includes: after the reaction is complete, the temperature of the reaction system is lowered to room temperature, 3-5wt% sodium bicarbonate aqueous solution is added to the reaction system to adjust the pH of the system to 7, the system is allowed to stand and separated, the upper oil phase is washed with purified water until neutral, and then transferred to a rotary evaporator with a water bath temperature of 80-90℃ to remove low-boiling substances under reduced pressure to obtain amino-modified polysiloxane.

[0015] The present invention also proposes an antistatic plastic packaging film, which is prepared by the above-described method for preparing an antistatic plastic packaging film.

[0016] The present invention has the following beneficial effects: This invention involves block bonding of PP-g-MAH with supported polysiloxane, and modifying the block chains with 6-cyclopropyl-1,2,4-triazine to prepare a silane-based PP blend. Using polypropylene as the plastic matrix, the silane-based PP blend is used to reinforce the plastic matrix before blown film fabrication. The silane-based PP blend, through the reinforcement of the supported polysiloxane with PP-g-MAH, enhances the compatibility of the supported polysiloxane with PP, allowing the supported polysiloxane to be uniformly dispersed in the plastic matrix. The supported polysiloxane is flexible... The amorphous phase of the Si-O-Si main chain and the side groups of the strongly polar imidazole onium salt group forms a nanoscale dispersed phase under PP-g-MAH compatibility. The dispersed nanosites increase the nucleation density, making the spherulites smaller, thereby reducing light scattering and improving the transmittance of the material. 6-cyclopropyl-1,2,4-triazine-3-amine is a nitrogen-containing heterocyclic compound. The lone pair electrons on the nitrogen atom can form hydrogen bonds or van der Waals forces with the β crystal form of the PP molecular chain, inducing the generation of the β crystal form, increasing the number of crystal nuclei, refining the crystal size, and thus improving the transmittance.

[0017] This invention also prepares hydrogen-terminated amino-modified polysiloxanes using octamethylcyclotetrasiloxane and aminopropylmethyldimethoxysilane as raw materials. The amino groups serve as reactive sites, providing loading sites for 4-epoxypropyloxy-TEMPO radicals and N-methylimidazole. The hydrogen-terminated polysiloxane chain undergoes hydrosilylation with 3-buten-1-amine to form amino modifications on the polysiloxane chain, resulting in PP-g-MAH. During melt blending, maleic anhydride on the molecular chain undergoes a ring-opening reaction with amine groups to generate amide / imide bonds. This permanently connects the nonpolar PP chains, which are inherently incompatible, with the polar PDMS ionic segments, reducing phase separation and forming a stronger interface. During tensile stress, stress can be more effectively transferred from the PP matrix to the flexible PDMS / ionic network. The imidazolium, amide, and carbonyl dipoles of the supported polysiloxane molecules form ionic dipole associations, improving tensile strength. At the same time, the physical crosslinking points of this reversible and dynamic dipole association continuously de-associate and recombine during tensile stress, dissipating energy and delaying fracture, thus increasing the nominal fracture strain of the material.

[0018] This invention also modifies the polysiloxane chain with imidazolium salt side groups, the imidazolium ring being positively charged and the anionic moiety Cl... - By introducing polar / nitrogen- and oxygen-containing functional groups such as anhydride groups, triazine amines, and TEMPO into nonpolar polypropylene, the affinity of the imidazolium ring for Cl is reduced. - The coulombic interaction between them causes the anion Cl to - It can more freely de-associate and re-associate, improving the antistatic properties of plastic packaging films. Furthermore, the low surface energy of polysiloxane chains promotes the migration of loaded polysiloxanes to the surface of plastic packaging films, further enhancing their antistatic properties. TEMPO modified on the loaded polysiloxanes can capture free radicals. The electronic structure of the triazine ring of 6-cyclopropyl-1,2,4-triazine-3-amine is an aromatic heterocycle containing three nitrogen atoms. The conjugated π-electron system of the triazine ring can absorb ultraviolet light and consume light energy through electronic transitions, reducing the damage of ultraviolet rays to the PP backbone. The steric hindrance effect of cyclopropyl can enhance the photostability of molecules, prevent photolysis, further improve the aging resistance of plastic packaging films, prevent yellowing due to aging, and thus maintain the light transmittance of plastic packaging films. Detailed Implementation

[0019] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In this invention, the CAS number of the 4-epoxypropyloxy-TEMPO radical is 122413-85-8; In this invention, the CAS number of 6-cyclopropyl-1,2,4-triazine-3-amine is 2918992-79-5; In this invention, PP-g-MAH is commercially available maleic anhydride-grafted polypropylene with a maleic anhydride grafting rate of 1.8-2%, a content of ≥98%, a density of 0.92 g / cm3, a melting point (DSC) of 150℃, and a melt flow rate of 70-110 g / 10 min. In this invention, PP is a commercially available material, specifically the Sinopec Maoming CP800M.

[0021] Example 1 This embodiment provides a method for preparing an antistatic plastic packaging film, including the following steps: Step 1: Preparation of amino-modified polysiloxane Weigh out 150g of octamethylcyclotetrasiloxane, 60g of aminopropylmethyldimethoxysilane, and 30mL of 60wt% sulfuric acid and add them to a reaction flask. Stir the mixture and raise the temperature of the reaction flask to 85℃. Maintain the temperature for 50min. Add 22g of end-capping agent 1,1,3,3-tetramethyldisiloxane to the reaction flask and maintain the temperature for 100min. Lower the temperature of the reaction flask to room temperature and add 3wt% sodium bicarbonate aqueous solution to adjust the pH of the system to 7. Allow the mixture to stand and separate the layers. Wash the upper oil phase with purified water until neutral and transfer it to a rotary evaporator with a water bath temperature of 80℃. Evaporate the rotary evaporator to a negative pressure of -0.1MPa and remove low-boiling substances under reduced pressure to obtain amino-modified polysiloxane.

[0022] Under sulfuric acid catalysis, octamethylcyclotetrasiloxane and aminopropylmethyldimethoxysilane undergo hydrolysis to form siloxane segments with silanol activity. Then, condensation occurs between the silanol groups to form amino-modified polysiloxane segments. 1,1,3,3-tetramethyldisiloxane is used as a capping agent, and after hydrolysis, silanol-modified amino-modified polysiloxanes are formed on the amino-modified polysiloxane segments.

[0023] Step 2: Preparation of TEMPO-modified polysiloxane Weigh out 150g of amino-modified polysiloxane, 1000mL of toluene, and 24g of 4-epoxypropyloxy-TEMPO radicals and add them to a reaction flask. Stir the mixture and raise the temperature of the reaction flask to 70℃. Maintain the temperature for 3 hours. Introduce argon gas into the reaction flask and lower the temperature to -5℃ under the argon atmosphere. Add 70g of chloroacetyl chloride dropwise to the reaction flask. After the addition is complete, raise the temperature of the reaction flask to room temperature and maintain the temperature for 6 hours. Add 10wt% sodium bicarbonate solution to the reaction flask and stir for 20 minutes. Allow the mixture to stand and separate the liquids. Wash the organic phase three times with purified water and transfer it to a rotary evaporator with a water bath temperature of 80℃. Evaporate the rotary evaporator to a negative pressure of -0.1MPa and remove low-boiling substances under reduced pressure to obtain TEMPO-modified polysiloxane.

[0024] The amino groups on the amino-modified polysiloxane molecular chain undergo ring-opening condensation with 4-epoxypropyloxy-TEMPO radicals to form TEMPO radical modification on the polysiloxane chain. Chloroacetyl chloride reacts with the remaining amino or hydroxyl groups on the amino-modified polysiloxane molecular chain to form ethyl chloride modification. During the reaction, by controlling the excess of chloroacetyl chloride, the active reaction sites such as amino / hydroxyl groups on the amino-modified polysiloxane are completely reacted, avoiding the presence of amino / hydroxyl residues on the TEMPO-modified polysiloxane molecular chain, thus preparing TEMPO-modified polysiloxane.

[0025] Step 3: Preparation of TEMPO-based activated polysiloxane Chloroplatinic acid and triphenylphosphine were mixed in a weight ratio of 3:1 to obtain a mixed catalyst; Weigh out 150g of TEMPO-modified polysiloxane, 18g of 3-butene-1-amine, 600mL of toluene, and 0.2g of mixed catalyst and add them to a reaction flask. Stir the mixture and raise the temperature of the reaction flask to 100℃. Keep the reaction flask at this temperature for 8 hours. Then, apply a negative pressure to the reaction flask to -0.1MPa and remove low-boiling substances by vacuum distillation to obtain TEMPO-based activated polysiloxane.

[0026] A mixed catalyst catalyzes the addition of olefin double bonds on the 3-butene-1-amine molecule to silane on the TEMPO-modified polysiloxane molecular chain, forming terminal amino groups on the TEMPO-modified polysiloxane molecular chain to prepare TEMPO-based activated polysiloxane.

[0027] Step 4: Preparation of supported polysiloxane Toluene and N,N-dimethylformamide were mixed at a volume ratio of 7:2 to obtain a toluene solution; Weigh out 210g of TEMPO-based activated polysiloxane, 60g of N-methylimidazole, and 900mL of toluene solution and add them to a reaction flask. Stir the mixture and raise the temperature of the reaction flask to 78℃. Keep the mixture at this temperature for 20h. Then lower the temperature of the reaction flask to room temperature and add 1000mL of purified water to the reaction flask. Stir and disperse the mixture for 20min. Allow the mixture to stand and separate the liquids. Wash the organic phase three times with purified water and transfer it to a rotary evaporator with a water bath temperature of 80℃. Apply a negative pressure of -0.1MPa to the rotary evaporator and remove low-boiling substances by vacuum evaporation to obtain the supported polysiloxane.

[0028] The chloroacetyl group on the TEMPO-activated polysiloxane molecular chain is a good leaving group site, while the imidazole nitrogen atom in the N-methylimidazolium molecule that is not substituted by methyl has strong nucleophilicity and can attack the methyl carbon of ethyl chloride through the SN2 mechanism. The chloride ion leaves, and an imidazole onium salt group is generated on the side chain of the TEMPO-activated polysiloxane, forming a "supported" structure, thus preparing the supported polysiloxane.

[0029] Step 5: Prepare plastic packaging film Weigh out the following components by weight: 50 parts of PP-g-MAH, 18 parts of supported polysiloxane, and 3 parts of 6-cyclopropyl-1,2,4-triazine-3-amine. Add them to a mixer at 170°C and mix for 10 minutes. After cooling, discharge the mixture to obtain a silane PP mixture. During the high-temperature mixing process, the maleic anhydride on the PP-g-MAH molecule undergoes chemical bonding with the amino groups on the supported polysiloxane or 6-cyclopropyl-1,2,4-triazine-3-amine molecule. The polypropylene segments on the PP-g-MAH form co-intercalation bonds with the polysiloxane segments of the supported polysiloxane, and the co-intercalation mixed system also has 6-cyclopropyl-1,2,4-triazine modification.

[0030] Oleamide, sodium stearate, diisobutyl phthalate, and antioxidant 168 were mixed in a weight ratio of 2:3:5:2 to obtain the auxiliary additive. Weigh out 50 parts by weight of silane PP mixture, 50 parts of PP, and 2 parts of auxiliary additives and add them to a twin-screw extruder. Set the temperatures of the four temperature zones of the twin-screw extruder from the feed end to the discharge end to 225℃, 230℃, 230℃, and 235℃ respectively. After melting and mixing for 2 minutes, extrude the mixture into a blown film extruder. Set the blown film temperature to 220℃ and extrude the blown film to obtain a plastic packaging film with a thickness of 30μm.

[0031] Example 2 This embodiment provides a method for preparing an antistatic plastic packaging film, including the following steps: Step 1: Preparation of amino-modified polysiloxane Weigh out 150g of octamethylcyclotetrasiloxane, 65g of aminopropylmethyldimethoxysilane, and 35mL of 65wt% sulfuric acid and add them to a reaction flask. Stir the mixture and raise the temperature of the reaction flask to 90℃. Maintain the temperature for 55min. Add 24g of end-capping agent 1,1,3,3-tetramethyldisiloxane to the reaction flask and maintain the temperature for 110min. Lower the temperature of the reaction flask to room temperature and add 4wt% sodium bicarbonate aqueous solution to adjust the pH of the system to 7. Allow the mixture to stand and separate the layers. Wash the upper oil phase with purified water until neutral and transfer it to a rotary evaporator with a water bath temperature of 85℃. Evaporate the rotary evaporator to a negative pressure of -0.1MPa and remove low-boiling substances under reduced pressure to obtain amino-modified polysiloxane.

[0032] Step 2: Preparation of TEMPO-modified polysiloxane Weigh out 150g of amino-modified polysiloxane, 1000mL of toluene, and 26g of 4-epoxypropyloxy-TEMPO radicals and add them to a reaction flask. Stir the mixture and raise the temperature of the reaction flask to 75℃. Maintain the temperature for 4 hours. Introduce argon gas into the reaction flask and lower the temperature to -7℃ under the argon atmosphere. Add 70g of chloroacetyl chloride dropwise to the reaction flask. After the addition is complete, raise the temperature of the reaction flask to room temperature and maintain the temperature for 7 hours. Add 10wt% sodium bicarbonate solution to the reaction flask and stir for 25 minutes. Allow the mixture to stand and separate the liquids. Wash the organic phase three times with purified water and transfer it to a rotary evaporator with a water bath temperature of 85℃. Evaporate the rotary evaporator to a negative pressure of -0.1MPa and remove low-boiling substances under reduced pressure to obtain TEMPO-modified polysiloxane.

[0033] Step 3: Preparation of TEMPO-based activated polysiloxane Chloroplatinic acid and triphenylphosphine were mixed in a weight ratio of 3:1 to obtain a mixed catalyst; Weigh out 150g of TEMPO-modified polysiloxane, 20g of 3-butene-1-amine, 600mL of toluene, and 0.2g of mixed catalyst and add them to a reaction flask. Stir the mixture and raise the temperature of the reaction flask to 105℃. Keep the reaction flask at this temperature for 9 hours. Then, reduce the pressure of the reaction flask to -0.1MPa and remove the low-boiling-point substances by vacuum distillation to obtain TEMPO-based activated polysiloxane.

[0034] Step 4: Preparation of supported polysiloxane Toluene and N,N-dimethylformamide were mixed at a volume ratio of 7:2 to obtain a toluene solution; Weigh out 210g of TEMPO-based activated polysiloxane, 60g of N-methylimidazole, and 900mL of toluene solution and add them to a reaction flask. Stir the mixture and raise the temperature of the reaction flask to 80℃. Keep the mixture at this temperature for 21h. Then lower the temperature of the reaction flask to room temperature and add 1000mL of purified water to the reaction flask. Stir and disperse the mixture for 25min. Allow the mixture to stand and separate the liquids. Wash the organic phase three times with purified water and transfer it to a rotary evaporator with a water bath temperature of 85℃. Apply a negative pressure of -0.1MPa to the rotary evaporator and remove low-boiling substances by vacuum evaporation to obtain the supported polysiloxane.

[0035] Step 5: Prepare plastic packaging film Weigh out the following by weight: 50 parts of PP-g-MAH, 20 parts of supported polysiloxane, and 4 parts of 6-cyclopropyl-1,2,4-triazine-3-amine. Add them to a mixer at 180℃ and mix for 13 minutes. After cooling, discharge the mixture to obtain a silane PP mixture. Hexamethylenetetramine, calcium stearate, diisooctyl phthalate, and antioxidant 100 were mixed in a weight ratio of 2:3:5:2 to obtain the auxiliary additive. Weigh out 50 parts by weight of silane PP mixture, 55 parts of PP, and 2.5 parts of auxiliary additives and add them to a twin-screw extruder. Set the temperatures of the four temperature zones of the twin-screw extruder from the feed end to the discharge end to 225℃, 230℃, 230℃, and 235℃ respectively. After melting and mixing for 2.5 minutes, extrude the mixture into a blown film extruder. Set the blown film temperature to 225℃ and extrude the blown film to obtain a plastic packaging film with a thickness of 40μm.

[0036] Example 3 This embodiment provides a method for preparing an antistatic plastic packaging film, including the following steps: Step 1: Preparation of amino-modified polysiloxane Weigh out 150g of octamethylcyclotetrasiloxane, 70g of aminopropylmethyldimethoxysilane, and 40mL of 70wt% sulfuric acid and add them to a reaction flask. Stir the mixture and raise the temperature of the reaction flask to 95℃. Maintain the temperature for 60min. Add 26g of end-capping agent 1,1,3,3-tetramethyldisiloxane to the reaction flask and maintain the temperature for 120min. Lower the temperature of the reaction flask to room temperature and add 5wt% sodium bicarbonate aqueous solution to adjust the pH of the system to 7. Allow the mixture to stand and separate the layers. Wash the upper oil phase with purified water until neutral and transfer it to a rotary evaporator with a water bath temperature of 90℃. Evaporate the rotary evaporator to a negative pressure of -0.1MPa and remove low-boiling substances under reduced pressure to obtain amino-modified polysiloxane.

[0037] Step 2: Preparation of TEMPO-modified polysiloxane Weigh out 150g of amino-modified polysiloxane, 1000mL of toluene, and 28g of 4-epoxypropyloxy-TEMPO radicals and add them to a reaction flask. Stir the mixture and raise the temperature of the reaction flask to 80℃. Maintain the temperature for 5 hours. Introduce argon gas into the reaction flask and lower the temperature to -10℃ under the argon atmosphere. Add 70g of chloroacetyl chloride dropwise to the reaction flask. After the addition is complete, raise the temperature of the reaction flask to room temperature and maintain the temperature for 8 hours. Add 10wt% sodium bicarbonate solution to the reaction flask and stir for 30 minutes. Allow the mixture to stand and separate the liquids. Wash the organic phase three times with purified water and transfer it to a rotary evaporator with a water bath temperature of 90℃. Evaporate the rotary evaporator to a negative pressure of -0.1MPa and remove low-boiling substances under reduced pressure to obtain TEMPO-modified polysiloxane.

[0038] Step 3: Preparation of TEMPO-based activated polysiloxane Chloroplatinic acid and triphenylphosphine were mixed in a weight ratio of 3:1 to obtain a mixed catalyst; Weigh out 150g of TEMPO-modified polysiloxane, 22g of 3-butene-1-amine, 600mL of toluene, and 0.2g of mixed catalyst and add them to a reaction flask. Stir the mixture and raise the temperature of the reaction flask to 110℃. Keep the reaction at this temperature for 10h. Then, apply a negative pressure to the reaction flask to -0.1MPa and remove low-boiling substances by vacuum distillation to obtain TEMPO-based activated polysiloxane.

[0039] Step 4: Preparation of supported polysiloxane Toluene and N,N-dimethylformamide were mixed at a volume ratio of 7:2 to obtain a toluene solution; Weigh out 210g of TEMPO-based activated polysiloxane, 60g of N-methylimidazole, and 900mL of toluene solution and add them to a reaction flask. Stir the mixture and raise the temperature of the reaction flask to 82℃. Keep the mixture at this temperature for 22h. Then lower the temperature of the reaction flask to room temperature and add 1000mL of purified water to the reaction flask. Stir and disperse the mixture for 30min. Allow the mixture to stand and separate the liquids. Wash the organic phase three times with purified water and transfer it to a rotary evaporator with a water bath temperature of 90℃. Apply a negative pressure of -0.1MPa to the rotary evaporator and remove low-boiling substances by vacuum evaporation to obtain the supported polysiloxane.

[0040] Step 5: Prepare plastic packaging film Weigh out the following by weight: 50 parts of PP-g-MAH, 22 parts of supported polysiloxane, and 5 parts of 6-cyclopropyl-1,2,4-triazine-3-amine. Add them to a mixer at 190℃ and mix for 15 minutes. After cooling, discharge the mixture to obtain a silane PP mixture. Octylamide, zinc stearate, diisopropyl phthalate, and antioxidant 168 were mixed in a weight ratio of 2:3:5:2 to obtain the auxiliary additive. Weigh out 50 parts by weight of silane PP mixture, 60 parts of PP and 3 parts of auxiliary additives and add them to a twin-screw extruder. Set the temperatures of the four temperature zones of the twin-screw extruder from the feed end to the discharge end to 225℃, 230℃, 230℃ and 235℃ respectively. After melting and mixing for 3 minutes, extrude the mixture into a blown film extruder. Set the blown film temperature to 230℃ and extrude the blown film to obtain a plastic packaging film with a thickness of 50μm.

[0041] Comparative Example 1 The difference between this comparative example and Example 3 is that in step 1, the amount of octamethylcyclotetrasiloxane is reduced to 50g.

[0042] Comparative Example 2 The difference between this comparative example and Example 3 is that step 3 is omitted, and the TEMPO-modified polysiloxane in step 4 is replaced with the TEMPO-based activated polysiloxane in step 2.

[0043] Comparative Example 3 The difference between this comparative example and Example 3 is that 6-cyclopropyl-1,2,4-triazine-3-amine was not added in step 5.

[0044] Performance testing: The light transmittance of the plastic packaging films prepared in Examples 1-3 and Comparative Examples 1-3 was determined in accordance with the standard GB / T 2410-2008 "Determination of light transmittance and haze of transparent plastics". The longitudinal tensile force and longitudinal nominal strain at break of the plastic packaging films prepared in Examples 1-3 and Comparative Examples 1-3 were determined in accordance with the standard GB / T 10004-2008 "Dry lamination and extrusion lamination of plastic composite films and bags for packaging". The volume resistivity of the plastic packaging films prepared in Examples 1-3 and Comparative Examples 1-3 was determined according to the standard GB / T 15662-1995 "Test Method for Volume Resistivity of Conductive and Antistatic Plastics". Referring to Method B of GB / T 16422.3-2022 "Laboratory Light Source Exposure Test Methods for Plastics - Part 3: Fluorescent Ultraviolet Lamps", artificial accelerated weathering was performed using a UVA-351 lamp to determine the light transmittance of the plastic packaging films prepared in Examples 1-3 and Comparative Examples 1-3 after aging for 100 hours. The specific test results are shown in Table 1 below.

[0045] Table 1 - Performance Test Data of Samples Data Analysis: The plastic packaging film prepared by this invention has a light transmittance of 88.9% before aging, a transmittance of 85.6% after aging, and a volume resistivity of 0.73 × 10⁻⁶. 10The tensile strength reached 46.7 N and the nominal strain at break reached 225%, with all performance test data superior to the comparative example. This indicates that the present invention strengthens the polypropylene plastic matrix by block bonding of PP-g-MAH with supported polysiloxane and 6-cyclopropyl-1,2,4-triazine-3-amine, thereby effectively improving the light transmittance and antistatic properties of the plastic packaging film, as well as its toughness and aging resistance.

[0046] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing an antistatic plastic packaging film, characterized in that, Includes the following steps: S1. Mix TEMPO-activated polysiloxane, N-methylimidazol and toluene solution, raise the temperature of the reaction system to 78-82℃, keep the reaction at this temperature for 20-22h, and then perform post-treatment to obtain supported polysiloxane. S2. Add PP-g-MAH, supported polysiloxane, and 6-cyclopropyl-1,2,4-triazine-3-amine to a mixer at a temperature of 170-190℃, mix for 10-15 minutes, cool down and discharge to obtain silane PP mixture; S3. Add the silane PP mixture, PP and auxiliary additives to a twin-screw extruder, melt mix for 2-3 minutes and then extrude into a blown film extruder to obtain a plastic packaging film with a thickness of 30-50μm.

2. The method for preparing an antistatic plastic packaging film according to claim 1, characterized in that, In step S1, the ratio of TEMPO-modified polysiloxane, N-methylimidazole, and toluene solution is 7g:2g:30mL, and the toluene solution is composed of toluene and N,N-dimethylformamide in a volume ratio of 7:2; in step S2, the weight ratio of PP-g-MAH, supported polysiloxane, and 6-cyclopropyl-1,2,4-triazine-3-amine is 50:18-22:3-5.

3. The method for preparing an antistatic plastic packaging film according to claim 1, characterized in that, In step S3, the weight ratio of the silane PP mixture, PP, and auxiliary additives is 50:50-60:2-3. The auxiliary additives are composed of lubricant, dispersant, plasticizer, and antioxidant in a weight ratio of 2:3:5:

2. The lubricant is one or more of oleamide, hexamethylenetetramine, and octylamide. The dispersant is one or more of stearates. The plasticizer is phthalate. The antioxidant is antioxidant 168 or antioxidant 100. The temperatures of the four temperature zones of the twin-screw extruder from the feed end to the discharge end are 225°C, 230°C, 230°C, and 235°C, respectively. The blowing temperature of the blown film extruder is 220-230°C.

4. The method for preparing an antistatic plastic packaging film according to claim 1, characterized in that, The preparation method of TEMPO-based activated polysiloxane is as follows: TEMPO-modified polysiloxane, 3-butene-1-amine, toluene and mixed catalyst are mixed, the temperature of the reaction system is raised to 100-110℃, the reaction is kept at the temperature for 8-10h, and then post-processed to obtain TEMPO-based activated polysiloxane.

5. The method for preparing an antistatic plastic packaging film according to claim 4, characterized in that, The ratio of TEMPO-modified polysiloxane, 3-butene-1-amine, toluene, and the mixed catalyst is 15g:1.8-2.2g:60mL:0.02g. The catalyst is composed of chloroplatinic acid and triphenylphosphine in a weight ratio of 3:

1.

6. The method for preparing an antistatic plastic packaging film according to claim 4, characterized in that, The preparation method of TEMPO modified polysiloxane is as follows: amino-modified polysiloxane, toluene and 4-epoxypropyloxy-TEMPO free radical are mixed, the reaction system temperature is raised to 70-80℃ and kept at this temperature for 3-5 hours, an inert gas is introduced into the reaction system, and the reaction system temperature is lowered to -5~-10℃ under the inert gas atmosphere, chloroacetyl chloride is added dropwise to the reaction system, and after the addition is complete, the reaction system temperature is raised to room temperature and kept at this temperature for 6-8 hours. After post-treatment, TEMPO modified polysiloxane is obtained.

7. The method for preparing an antistatic plastic packaging film according to claim 6, characterized in that, The ratio of amino-modified polysiloxane, toluene, 4-epoxypropyloxy-TEMPO radical and chloroacetyl chloride is 15g:100mL:2.4-2.8g:7g.

8. The method for preparing an antistatic plastic packaging film according to claim 6, characterized in that, The preparation method of amino-modified polysiloxane is as follows: octamethylcyclotetrasiloxane, aminopropylmethyldimethoxysilane and catalyst are mixed, the temperature of the reaction system is raised to 85-95℃, and the reaction is maintained at this temperature for 50-60 min. An end-capping agent is added to the reaction system, and the reaction is maintained at this temperature for 100-120 min. After post-treatment, amino-modified polysiloxane is obtained.

9. The method for preparing an antistatic plastic packaging film according to claim 8, characterized in that, The ratio of octamethylcyclotetrasiloxane, aminopropylmethyldimethoxysilane, catalyst, and end-capping agent is 15g:6-7g:3-4mL:2.2-2.6g, the end-capping agent is 1,1,3,3-tetramethyldisiloxane, and the catalyst is 60-70wt% sulfuric acid.

10. An antistatic plastic packaging film, characterized in that, The antistatic plastic packaging film is prepared using the method described in any one of claims 1-9.

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