Flame-retardant packaging material and preparation method thereof

Abstract

The invention discloses a flame-retardant packaging material and a preparation method thereof, and relates to the technical field of materials. When the flame-retardant packaging material is prepared, firstly, polystyrene is grafted with thiacalixarene containing monovinyl to obtain modified polystyrene, and secondly, tertiary amine-terminated silicone oil and chloropropane react to obtain modified silicone oil; grafting mono-6-O-(p-toluenesulfonyl)-beta-cyclodextrin on the surface of the pretreated silicon dioxide, and reacting with phosphoric acid and urea to obtain modified silicon dioxide; and finally, carrying out melt blending on the modified polystyrene, the modified silicon dioxide and the modified silicone oil, and carrying out hot pressing to obtain the flame-retardant packaging material. The flame-retardant packaging material prepared by the invention has good antibacterial, anti-aging and flame-retardant properties.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of materials, in particular to a flame-retardant packaging material and a preparation method thereof. BACKGROUND

[0002] The flame-retardant packaging material is an indispensable functional material in modern industry, and is widely used in the protection and transportation demand of food, electronic products, medicines and cosmetics and other fields. With the increasingly stringent environmental protection regulations and the emphasis of consumers on safety performance, traditional packaging materials such as paperboard, plastic (polyethylene, polypropylene, polystyrene), glass and composite materials are facing higher technical challenges.

[0003] Polystyrene is widely used as a cushioning material, a container and a foam packaging due to its non-toxic transparency, excellent processing performance and good heat and insulation properties. However, its inherent flammability, poor weather resistance and insufficient antibacterial ability limit its application in high-risk scenarios. For example, polystyrene is extremely flammable and releases toxic gases under high temperature or open flame conditions, leading to fire hazards; the instability of the benzene group in its molecular structure makes it prone to yellowing and embrittlement when exposed to ultraviolet light or humid environments for a long time, affecting the mechanical strength and appearance of the packaging; in addition, in food or medicine packaging, polystyrene surfaces are prone to adsorbing microorganisms and breeding bacteria, which may cause food safety problems or drug contamination. Therefore, it is an urgent need in the industry to develop a new type of packaging material with flame retardant, anti-aging and antibacterial properties. SUMMARY

[0004] The present application aims to provide a flame-retardant packaging material and a preparation method thereof to solve the problems in the prior art.

[0005] In order to solve the above technical problems, the present application provides the following technical scheme: A preparation method of a flame-retardant packaging material, comprising the following preparation steps: (1) reacting a thiacalixarene with allyl chloride to obtain a monosubstituted vinyl thiacalixarene; grafting the monosubstituted vinyl thiacalixarene onto polystyrene to obtain modified polystyrene; (2) reacting N-methyloctylamine with allyl chloride to obtain a vinyl tertiary amine; reacting hydrogen-containing silicone oil with the vinyl tertiary amine to obtain a terminal tertiary amine silicone oil; (3) reacting the terminal tertiary amine silicone oil with 1-chloropropane to obtain a modified silicone oil; (4) reacting 3-aminopropyl triethoxysilane with nano-silicon dioxide to obtain pretreated nano-silicon dioxide; reacting mono-6-O-(p-toluenesulfonyl)-β-cyclodextrin with the pretreated silicon dioxide to obtain a pre-modified silicon dioxide; (5) reacting the pre-modified silicon dioxide with phosphoric acid and urea to obtain a modified silicon dioxide; (6) The modified polystyrene, modified silica and modified silicone oil are melt-blended and pressed into sheets using a flat-plate vulcanizing machine to obtain a flame-retardant packaging material.

[0006] As an optimization, the preparation method of the modified polystyrene in step (1) is as follows: monosubstituted vinylthiacalixarene, polystyrene, and dibenzoyl peroxide are uniformly mixed, heated to 70-80°C, and reacted for 35-40 hours to obtain the modified polystyrene; the mass ratio of polystyrene, monosubstituted vinylthiacalixarene, and dibenzoyl peroxide is 1:(0.1-0.2):(0.006-0.008).

[0007] As an optimization, the preparation method of the monosubstituted vinyl thiacalixarene is as follows: thiacalixarene, triethylamine, potassium iodide, and tetrahydrofuran are mixed, heated to 55-60° C. and refluxed for 30-40 minutes, allyl chloride is added dropwise at a rate of 0.2 mL / min, and refluxed for 4-5 days to obtain a monosubstituted vinyl thiacalixarene; the molar ratio of thiacalixarene, allyl chloride, triethylamine, and potassium iodide is 1:(1.3-1.5):(1.5-2.0):(0.08-0.1), and the mass ratio of thiacalixarene and tetrahydrofuran is 1:(20-30).

[0008] As an optimization, the preparation method of the terminated tertiary amine silicone oil in step (2) is as follows: hydrogen-containing silicone oil and vinyl tertiary amine are mixed, heated to 40-50°C under nitrogen protection, a catalyst is added, and the reaction is carried out for 2-3 hours to obtain the terminated tertiary amine silicone oil; the molar ratio of hydrogen-containing silicone oil to vinyl tertiary amine is 1:(2.1-2.3); the mass of the catalyst is 0.001-0.002 times that of the hydrogen-containing silicone oil.

[0009] As an optimization, the preparation method of the vinyl tertiary amine is as follows: anhydrous potassium carbonate and N-methyloctylamine are dissolved in acetonitrile, the temperature is raised to 35-40° C., allyl chloride is added dropwise at a rate of 0.2-0.3 mL / min, and after the addition is completed, the temperature is raised to 55-65° C. and reacted for 6-8 hours to obtain the vinyl tertiary amine; the molar ratio of N-methyloctylamine, allyl chloride, and anhydrous potassium carbonate is (1.3-1.5):1:(1.2-1.5); the mass of acetonitrile is 10-12 times that of N-methyloctylamine.

[0010] As an optimization, the preparation method of the modified silicone oil in step (3) is as follows: under nitrogen protection and closed conditions, the terminal tertiary amine silicone oil and 1-chloropropane are mixed, the temperature is raised to 60-70°C, and the reaction is carried out under nitrogen protection for 14-16 hours to obtain the modified silicone oil; the molar ratio of the terminal tertiary amine silicone oil to 1-chloropropane is 1:(2.1-2.3).

[0011] As an optimization, the preparation method of the pre-modified silica in step (4) is as follows: 3-aminopropyltriethoxysilane and ethanol are mixed in a volume ratio of 1:4, acetic acid is used to adjust the pH of the solution to 4-5, and the solution is stirred and hydrolyzed for 30-40 minutes to obtain a hydrolyzed silane coupling agent; nano-silica is dispersed in anhydrous ethanol, the hydrolyzed silane coupling agent is added, and the temperature is raised to 70-80°C for reaction for 2-3 hours to obtain pretreated nano-silica; the mass ratio of nano-silica, anhydrous ethanol, and 3-aminopropyltriethoxysilane is 1:(10-12):(0.1-0.3); Mono-6-O-(p-toluenesulfonyl)-β-cyclodextrin, pretreated silica, and N-methylpyrrolidone are ultrasonically mixed, potassium iodide is added, heated to 70-80°C, and stirred for 6-7 hours to obtain pre-modified silica; the mass ratio of pretreated silica, mono-6-O-(p-toluenesulfonyl)-β-cyclodextrin, N-methylpyrrolidone, and potassium iodide is 1:(0.6-0.8):(30-40):(0.02-0.03).

[0012] As an optimization, the preparation method of the modified silica in step (5) is as follows: 1 / 2 of the urea is heated and dissolved, pre-modified silica and phosphoric acid are added, the temperature is raised to 80-85°C and the reaction is carried out for 3-4 hours, and the remaining urea is added and the reaction is continued for 2-3 hours to obtain modified silica; the mass ratio of pre-modified silica, phosphoric acid, and urea is 1:(1.2-1.5):(1.7-2.0).

[0013] As an optimization, the preparation method of the flame-retardant packaging material in step (6) is as follows: modified polystyrene, modified silicon dioxide, and modified silicone oil are melt-blended on a double-roll mixer in a mass ratio of 1:(0.2-0.4):(0.03-0.06), and after mixing, the mixture is pressed into sheets using a flat vulcanizer to obtain the flame-retardant packaging material.

[0014] The present invention also provides a flame retardant packaging material prepared according to the method for preparing the flame retardant packaging material.

[0015] Compared with the prior art, the present invention has the following beneficial effects: When preparing the flame-retardant packaging material, the present invention comprises the following steps: first, polystyrene is grafted with monovinyl-containing thiacalixarene to obtain modified polystyrene; second, tertiary amine-terminated silicone oil and 1-chloropropane are reacted to obtain modified silicone oil; mono-6-O-(p-toluenesulfonyl)-β-cyclodextrin is grafted onto the surface of pretreated silica, and then the modified silica is reacted with phosphoric acid and urea to obtain modified silica; finally, the modified polystyrene, modified silica and modified silicone oil are melt-blended and hot-pressed to obtain the flame-retardant packaging material.

[0016] First, polystyrene is grafted onto a monovinyl-containing thiacalixarene to obtain modified polystyrene. Allyl chloride reacts with the hydroxyl group on the benzene ring of the thiacalixarene to graft the vinyl group onto the calixarene. In the presence of dibenzoyl peroxide, the grafting reaction is carried out on the polystyrene. The thiacalixarene, through its sulfide group and aromatic fused ring structure, captures free radicals, inhibiting the thermal oxidative degradation of the polystyrene chain, thereby endowing the material with excellent anti-aging properties. Secondly, the flexibility of the siloxane chain segments in hydrogenated silicone oil can lower the glass transition temperature of polystyrene and improve processing fluidity. A click reaction occurs between the vinyl tertiary amine and the silicon-hydrogen bonds at both ends of the hydrogenated silicone oil, grafting tertiary amines onto both ends of the silicone oil molecular chain. After the tertiary amine-terminated silicone oil is quaternized with chloropropane, the long-chain alkyl quaternary ammonium cations destroy the lipid bilayer of the microbial cell membrane through electrostatic adsorption, thus giving the material excellent antibacterial properties. Silica, a common rigid inorganic filler, can reinforce and toughen pure polystyrene. The surface of pretreated silica also contains a large number of amino groups, which can be grafted with mono-6-O-(p-toluenesulfonyl)-β-cyclodextrin. β-cyclodextrin, as an environmentally friendly carbon-forming agent, reacts with phosphoric acid and urea through its remaining hydroxyl structure at high temperatures to form nitrogen-phosphorus-doped phosphates. During combustion, it catalyzes the formation of a dense, expanded carbon layer, which achieves condensed phase flame retardancy by isolating oxygen and blocking heat transfer. The positive charge of the modified silicone oil and the negative charge of the phosphate can improve the dispersibility of the modified silica in polystyrene through the electrostatic attraction between the positive and negative charges. Finally, the modified polystyrene, modified silica, and modified silicone oil are melt-blended and hot-pressed to produce a flame-retardant packaging material. The cavity structure of the thiacalixarene in the modified polystyrene side chain forms a host-guest complex with the quaternary ammonium salt on the modified silicone oil. The modified silicone oil acts as a crosslinker to form a dynamic crosslinked network, significantly improving the material's tensile strength. DETAILED DESCRIPTION

[0017] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0018] The polystyrene model in the following examples and comparative examples is 666D, purchased from Yanshan Petrochemical; the average particle size of the nano-silica is 200 nm; the molecular weight of the hydrogenated silicone oil is 2000, purchased from Jining Fangyu Chemical Co., Ltd.; the thiacalixarene is 2,4,6,8-tetrathia-1,3,5,7(1,3)-tetrabenzocyclooctaphen-12,32,52,72-tetrakis; the eluent is obtained by mixing dichloromethane, methanol and 25 wt % ammonia water, the volume ratio of dichloromethane to methanol is 7:1, and the volume of 25 wt % ammonia water added is 0.4% of the total volume of dichloromethane and methanol; the boiling range of the petroleum ether is 30-60° C.

[0019] Example 1: A method for preparing a flame retardant packaging material, comprising the following steps: (1) Thiacalixarene, triethylamine, potassium iodide and tetrahydrofuran were mixed, heated to 60°C and refluxed for 40 min, allyl chloride was added dropwise at a rate of 0.2 mL / min, and refluxed for 5 days. After the reaction was completed, the mixture was cooled to room temperature, the filtrate was filtered and retained, and the filtrate was evaporated under reduced pressure to 1 / 3 of the original volume. Anhydrous ethanol was used to precipitate the precipitate, which was filtered and washed with anhydrous ethanol and dried. The precipitate was then purified by chloroform / ethanol (V 氯仿 :V 乙醇 =1:1) and recrystallized to obtain monosubstituted vinylthiacalixarene; the molar ratio of thiacalixarene, allyl chloride, triethylamine, and potassium iodide was 1:1.3:1.5:0.08, and the mass ratio of thiacalixarene to tetrahydrofuran was 1:20; Monosubstituted vinylthiacalixarene, polystyrene, and dibenzoyl peroxide were mixed, heated to 80°C, reacted for 40 hours, precipitated with methanol, filtered, retained, and redissolved with acetone. The precipitate was precipitated again with methanol. After acetone redissolution and methanol precipitation four times, the modified polystyrene was washed with methanol and dried. The mass ratio of polystyrene, monosubstituted vinylthiacalixarene, and dibenzoyl peroxide was 1:0.1:0.006. (2) Anhydrous potassium carbonate and N-methyloctylamine were dissolved in acetonitrile, and the temperature was raised to 40°C. Allyl chloride was added dropwise at a rate of 0.3 mL / min. After the addition was completed, the temperature was raised to 65°C for reaction for 8 h. The filtrate was filtered and retained. The filtrate was evaporated at 50°C until inorganic salts precipitated. Dichloromethane with an equal volume of ethanol was added, and the inorganic salts were removed by filtration. The filtrate was retained and dried over anhydrous sodium sulfate for 30 min to remove the anhydrous sodium sulfate. The filtrate was evaporated under reduced pressure at 35°C to obtain a crude product. The crude product was purified by column chromatography (eluent: V 二氯甲烷 :V 甲醇 =7:1 + 0.4% 25wt% ammonia water) to obtain vinyl tertiary amine; the molar ratio of N-methyloctylamine, allyl chloride, and anhydrous potassium carbonate is 1.3:1:1.2; the mass of acetonitrile is 10 times that of N-methyloctylamine; The hydrogen-containing silicone oil and the vinyl tertiary amine are mixed, heated to 50℃ under nitrogen protection, and a catalyst chloroplatinic acid hexahydrate is added. The reaction is carried out at normal pressure and constant temperature for 3h, and then cooled to room temperature. The filtrate is reserved after filtration, and the end tertiary amine silicone oil is obtained by rotary evaporation at 60℃ and 0.08MPa. The molar ratio of the hydrogen-containing silicone oil and the vinyl tertiary amine is 1:2.1. The mass of the catalyst is 0.001 times that of the hydrogen-containing silicone oil. (3) The end tertiary amine silicone oil and 1-chloropropane are mixed under nitrogen protection and in a sealed condition, heated to 70℃, and reacted under nitrogen protection for 16h. The product is obtained by vacuum distillation at 40℃ and 0.08MPa for 1h, washed with petroleum ether, removed by fractional distillation, washed with ethyl ether, and dried in vacuum. The molar ratio of the end tertiary amine silicone oil and 1-chloropropane is 1:2.1. (4) 3-Aminopropyl triethoxysilane and ethanol are mixed in a volume ratio of 1:4, and the pH of the solution is adjusted to 5 using acetic acid. The solution is hydrolyzed by stirring for 40min to obtain a hydrolyzed silane coupling agent. Nano-silica is dispersed in anhydrous ethanol, and the hydrolyzed silane coupling agent is added. The mixture is heated to 80℃ and reacted for 3h. After the reaction is completed, the pretreated nano-silica is obtained by filtration, washing, and drying. The mass ratio of the nano-silica, anhydrous ethanol, and 3-aminopropyl triethoxysilane is 1:10:0.1. The mono-6-O-(p-toluenesulfonyl)-β-cyclodextrin, pretreated silica, and N-methyl pyrrolidone are ultrasonically mixed, and potassium iodide is added. The mixture is heated to 80℃ and continuously stirred for 7h. After cooling to room temperature, ethanol is added. The pretreated silica is obtained by filtration, washing, and drying. The mass ratio of the pretreated silica, mono-6-O-(p-toluenesulfonyl)-β-cyclodextrin, N-methyl pyrrolidone, and potassium iodide is 1:0.6:30:0.02. (5) Half of the urea is heated and dissolved. The pretreated silica and phosphoric acid are added. The mixture is heated to 85℃ and reacted for 4h. The remaining urea is added, and the reaction is continued for 3h. After the reaction is completed, the mixture is cooled at room temperature for 12h. The filtrate is reserved after filtration. The modified silica is obtained by precipitation using anhydrous ethanol, filtration, washing, and drying. The mass ratio of the pretreated silica, phosphoric acid, and urea is 1:1.2:1.7. (6) The modified polystyrene, modified silica, and modified silicone oil are melt blended on a double roller mixer in a mass ratio of 1:0.2:0.03. The front roller is at 165℃, and the rear roller is at 155℃. The mixture is pressed into a sheet using a flat vulcanizing machine at 170℃ and 14MPa for 5min to obtain the flame-retardant packaging material.

[0020] Example 2 A preparation method of a flame-retardant packaging material, the preparation method of the flame-retardant packaging material comprising the following preparation steps: (1) Thiacalixarene, triethylamine, potassium iodide and tetrahydrofuran were mixed, heated to 57°C and refluxed for 35 min, allyl chloride was added dropwise at a rate of 0.2 mL / min, and refluxed for 4 days. After the reaction was completed, it was cooled to room temperature, filtered and the filtrate was retained. When the volume was reduced to 1 / 3 of the original volume, anhydrous ethanol was used to precipitate the precipitate, filtered, washed with anhydrous ethanol, and dried. The precipitate was purified by chloroform / ethanol (V 氯仿 :V 乙醇 =1:1) and recrystallized to obtain monosubstituted vinylthiacalixarene; the molar ratio of thiacalixarene, allyl chloride, triethylamine, and potassium iodide was 1:1.4:1.7:0.09, and the mass ratio of thiacalixarene to tetrahydrofuran was 1:25; Monosubstituted vinylthiacalixarene, polystyrene, and dibenzoyl peroxide were mixed, heated to 75°C, reacted for 37 hours, precipitated with methanol, filtered, retained, and redissolved with acetone. The precipitate was precipitated again with methanol. After acetone redissolution and methanol precipitation four times, the modified polystyrene was washed with methanol and dried. The mass ratio of polystyrene, monosubstituted vinylthiacalixarene, and dibenzoyl peroxide was 1:0.15:0.007. (2) Anhydrous potassium carbonate and N-methyloctylamine were dissolved in acetonitrile, and the temperature was raised to 37°C. Allyl chloride was added dropwise at a rate of 0.25 mL / min. After the addition was completed, the temperature was raised to 50°C for reaction for 7 h. The filtrate was filtered and retained. The filtrate was evaporated at 50°C until inorganic salts precipitated. Dichloromethane with an equal volume of ethanol was added, and the inorganic salts were removed by filtration. The filtrate was retained and dried over anhydrous sodium sulfate for 30 min to remove the anhydrous sodium sulfate. The filtrate was evaporated under reduced pressure at 35°C to obtain a crude product. The crude product was purified by column chromatography (eluent: V 二氯甲烷 :V 甲醇 =7:1 + 0.4% 25wt% ammonia water) to obtain vinyl tertiary amine; the molar ratio of N-methyloctylamine, allyl chloride, and anhydrous potassium carbonate is 1.4:1:1.3; the mass of acetonitrile is 11 times that of N-methyloctylamine; The hydrogenated silicone oil and vinyl tertiary amine were mixed, heated to 45°C under nitrogen protection, and chloroplatinic acid hexahydrate as a catalyst was added. The mixture was reacted at normal pressure and constant temperature for 2.5 hours. The mixture was cooled to room temperature, and the filtrate was filtered and retained. The tertiary amine-terminated silicone oil was obtained by rotary evaporation at 60°C and 0.08 MPa. The molar ratio of the hydrogenated silicone oil to the vinyl tertiary amine was 1:2.2. The mass of the catalyst was 0.001 times that of the hydrogenated silicone oil. (3) Under nitrogen protection and sealed conditions, tertiary amine-terminated silicone oil and 1-chloropropane were mixed, heated to 65°C, reacted under nitrogen protection for 15 hours, and distilled under reduced pressure at 40°C and 0.08 MPa for 1 hour. The product was washed with petroleum ether, fractionated to remove the petroleum ether, then washed with ether and vacuum dried to obtain modified silicone oil; the molar ratio of tertiary amine-terminated silicone oil to 1-chloropropane was 1:2.2; (4) 3-aminopropyltriethoxysilane and ethanol were mixed in a volume ratio of 1:4, the pH of the solution was adjusted to 4.5 with acetic acid, and the mixture was stirred and hydrolyzed for 35 minutes to obtain a hydrolyzed silane coupling agent; nano-silica was dispersed in anhydrous ethanol, the hydrolyzed silane coupling agent was added, the temperature was raised to 75°C and the reaction was carried out for 2.5 hours. After the reaction was completed, the mixture was filtered, washed, and dried to obtain pretreated nano-silica; the mass ratio of nano-silica, anhydrous ethanol, and 3-aminopropyltriethoxysilane was 1:11:0.2; Mono-6-O-(p-toluenesulfonyl)-β-cyclodextrin, pretreated silica, and N-methylpyrrolidone were ultrasonically mixed, potassium iodide was added, and the mixture was heated to 75°C. After continuous stirring for 6.5 hours, the mixture was cooled to room temperature, ethanol was added, and the mixture was filtered, washed, and dried to obtain pre-modified silica; the mass ratio of pretreated silica, mono-6-O-(p-toluenesulfonyl)-β-cyclodextrin, N-methylpyrrolidone, and potassium iodide was 1:0.7:35:0.025; (5) 1 / 2 of the urea was heated and dissolved, and pre-modified silica and phosphoric acid were added. The temperature was raised to 83°C and the reaction was continued for 3.5 hours. The remaining urea was added and the reaction was continued for 2.5 hours. After the reaction was completed, the mixture was cooled at room temperature for 12 hours. The filtrate was filtered and retained. Anhydrous ethanol was used for precipitation. The modified silica was obtained by filtration, washing, and drying. The mass ratio of pre-modified silica, phosphoric acid, and urea was 1:1.3:1.9. (6) Modified polystyrene, modified silica, and modified silicone oil were melt-blended in a double-roll mixer at a mass ratio of 1:0.3:0.05, with the front roller at 162°C and the rear roller at 153°C. After mixing, they were pressed into sheets using a flat vulcanizer at 170°C and 14 MPa for 5 minutes to obtain a flame-retardant packaging material.

[0021] Example 3: A method for preparing a flame retardant packaging material, comprising the following steps: (1) Thiacalixarene, triethylamine, potassium iodide and tetrahydrofuran were mixed, heated to 55°C and refluxed for 30 min, allyl chloride was added dropwise at a rate of 0.2 mL / min, and refluxed for 4 days. After the reaction was completed, the mixture was cooled to room temperature, the filtrate was filtered and the filtrate was retained. When the volume was reduced to 1 / 3 of the original volume, anhydrous ethanol was used to precipitate the precipitate, which was filtered and washed with anhydrous ethanol and dried. The precipitate was purified by chloroform / ethanol (V 氯仿 :V 乙醇 =1:1) to obtain monosubstituted vinylthiacalixarene; the molar ratio of thiacalixarene, allyl chloride, triethylamine, and potassium iodide is 1:1.5:2.0:0.1, and the mass ratio of thiacalixarene to tetrahydrofuran is 1:30; Monosubstituted vinylthiacalixarene, polystyrene, and dibenzoyl peroxide were mixed, heated to 70°C, and reacted for 35 hours. The mixture was precipitated with methanol, filtered, retained, and redissolved with acetone. The mixture was precipitated again with methanol. The mixture was redissolved in acetone and precipitated with methanol four times, and then washed with methanol and dried to obtain modified polystyrene. The mass ratio of polystyrene, monosubstituted vinylthiacalixarene, and dibenzoyl peroxide was 1:0.2:0.008. (2) Anhydrous potassium carbonate and N-methyloctylamine were dissolved in acetonitrile, and the temperature was raised to 35°C. Allyl chloride was added dropwise at a rate of 0.2 mL / min. After the addition was completed, the temperature was raised to 55°C for reaction for 6 h. The filtrate was filtered and retained. The filtrate was evaporated at 50°C until inorganic salts precipitated. Dichloromethane with an equal volume of ethanol was added, and the inorganic salts were removed by filtration. The filtrate was retained and dried over anhydrous sodium sulfate for 30 min to remove the anhydrous sodium sulfate. The filtrate was evaporated under reduced pressure at 35°C to obtain a crude product. The crude product was purified by column chromatography (eluent: V 二氯甲烷 :V 甲醇 =7:1 + 0.4% 25wt% ammonia water) to obtain vinyl tertiary amine; the molar ratio of N-methyloctylamine, allyl chloride, and anhydrous potassium carbonate is 1.5:1:1.5; the mass of acetonitrile is 12 times that of N-methyloctylamine; The hydrogenated silicone oil and vinyl tertiary amine were mixed, heated to 40°C under nitrogen protection, and chloroplatinic acid hexahydrate as a catalyst was added. The mixture was reacted at normal pressure for 2 hours, cooled to room temperature, and the filtrate was filtered and retained. The tertiary amine-terminated silicone oil was obtained by rotary evaporation at 60°C and 0.08 MPa. The molar ratio of the hydrogenated silicone oil to the vinyl tertiary amine was 1:2.3. The mass of the catalyst was 0.002 times that of the hydrogenated silicone oil. (3) Under nitrogen protection and sealed conditions, the tertiary amine-terminated silicone oil and 1-chloropropane were mixed, heated to 60°C, reacted under nitrogen protection for 14 hours, and distilled under reduced pressure at 40°C and 0.08 MPa for 1 hour. The product was washed with petroleum ether, fractionated to remove the petroleum ether, then washed with ether and vacuum dried to obtain modified silicone oil; the molar ratio of the tertiary amine-terminated silicone oil to 1-chloropropane was 1:2.3; (4) 3-aminopropyltriethoxysilane and ethanol were mixed in a volume ratio of 1:4, the pH of the solution was adjusted to 4 with acetic acid, and the mixture was stirred and hydrolyzed for 30 minutes to obtain a hydrolyzed silane coupling agent; nano-silica was dispersed in anhydrous ethanol, the hydrolyzed silane coupling agent was added, the temperature was raised to 70°C and the reaction was carried out for 2 hours. After the reaction was completed, the mixture was filtered, washed, and dried to obtain pretreated nano-silica; the mass ratio of nano-silica, anhydrous ethanol, and 3-aminopropyltriethoxysilane was 1:12:0.3; Mono-6-O-(p-toluenesulfonyl)-β-cyclodextrin, pretreated silica, and N-methylpyrrolidone were ultrasonically mixed, potassium iodide was added, and the mixture was heated to 70°C. After continuous stirring for 6 hours, the mixture was cooled to room temperature, ethanol was added, and the mixture was filtered, washed, and dried to obtain pre-modified silica; the mass ratio of pretreated silica, mono-6-O-(p-toluenesulfonyl)-β-cyclodextrin, N-methylpyrrolidone, and potassium iodide was 1:0.8:40:0.03; (5) 1 / 2 of the urea was heated and dissolved, and pre-modified silica and phosphoric acid were added. The temperature was raised to 80°C and the reaction was continued for 3 hours. The remaining urea was added and the reaction was continued for 2 hours. After the reaction was completed, the mixture was cooled at room temperature for 12 hours. The filtrate was filtered and retained. Anhydrous ethanol was used for precipitation. The modified silica was obtained by filtration, washing, and drying. The mass ratio of pre-modified silica, phosphoric acid, and urea was 1:1.5:2.0. (6) Modified polystyrene, modified silica, and modified silicone oil were melt-blended in a double-roll mixer at a mass ratio of 1:0.4:0.06, with the front roller at 160°C and the rear roller at 150°C. After mixing, they were pressed into sheets using a flat vulcanizer at 170°C and 14 MPa for 5 minutes to obtain a flame-retardant packaging material.

[0022] Comparative Example 1: The method for preparing the flame-retardant packaging material of Comparative Example 1 differs from that of Example 2 in that the polystyrene is not modified. Specifically, step (1) is omitted. Step (6) is modified as follows: polystyrene, modified silica, and modified silicone oil are melt-blended in a mass ratio of 1:0.3:0.05 on a two-roll mixer, with the front roller at 162°C and the rear roller at 153°C. After mixing, the mixture is tableted using a flat vulcanizer at 170°C and 14 MPa for 5 minutes to obtain a flame-retardant packaging material. The remaining steps are the same as those of Example 2.

[0023] Comparative Example 2: The method for preparing the flame-retardant packaging material of Comparative Example 2 differs from that of Example 2 in that the silica is not modified. Specifically, steps (4) to (5) are not included. Step (6) is modified as follows: modified polystyrene, silica, and modified silicone oil are melt-blended in a mass ratio of 1:0.3:0.05 on a two-roll mixer, with the front roller at 162°C and the rear roller at 153°C. After mixing, the mixture is tableted using a flat vulcanizer at 170°C and 14 MPa for 5 minutes to obtain a flame-retardant packaging material. The remaining steps are the same as those of Example 2.

[0024] Comparative Example 3: The method for preparing the flame-retardant packaging material of Comparative Example 3 differs from that of Example 2 in that the hydrogenated silicone oil is not modified. Specifically, steps (2) to (3) are not included. Step (6) is modified as follows: modified polystyrene, modified silica, and hydrogenated silicone oil are melt-blended in a mass ratio of 1:0.3:0.05 on a two-roll mixer, with the front roller at 162°C and the rear roller at 153°C. After mixing, the mixture is tableted using a flat vulcanizer at 170°C and 14 MPa for 5 minutes to obtain a flame-retardant packaging material. The remaining steps are the same as those of Example 2.

[0025] Test Example 1: Antibacterial performance test: Test Method: The materials obtained in the Examples and Comparative Examples were prepared into 1 mm thick, 20 mm diameter discs. Antibacterial performance was tested according to ISO 22196-2011, "Evaluation of Surface Antimicrobial Properties of Plastics," using Escherichia coli (ATCC 25922) as the test bacteria. Results are shown in Table 1.

[0026] Table 1 From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 1, it can be found that the material prepared by the present invention has good antibacterial properties.

[0027] The antibacterial properties of Examples 1 to 3 are better than those of the comparative example, indicating that after the tertiary amine-terminated silicone oil is quaternized by chloropropane, the long-chain alkyl quaternary ammonium cation destroys the lipid bilayer of the microbial cell membrane through electrostatic adsorption, thereby giving the material good antibacterial properties.

[0028] Test Example 2: Mechanical properties test: Test method: Tensile strength was tested in accordance with GB / T 1040.2-2006 “Plastics—Determination of tensile properties—Molded and extruded plastics—Test conditions”. The specimen was a 1A dumbbell-shaped specimen and the test speed was 50 mm / min. The results are shown in Table 2.

[0029] Anti-aging performance test: Test Method: Samples were placed in a thermal oxygen aging chamber for 300 hours at 70°C and 60% relative humidity. The aged samples were then tested according to the mechanical properties test methods. The tensile strength retention before and after aging was calculated; the results are shown in Table 2.

[0030] Table 2 From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 2, it can be found that the material prepared by the present invention has good mechanical properties and anti-aging properties.

[0031] The mechanical properties and aging resistance of Examples 1 to 3 are superior to those of the comparative example. This illustrates that, first, polystyrene is grafted with a monovinyl-containing thiacalixarene to obtain modified polystyrene. Allyl chloride is reacted with the hydroxyl group on the benzene ring of the thiacalixarene to graft the vinyl group onto the calixarene. The grafting is then performed on the polystyrene in the presence of dibenzoyl peroxide. The thiacalixarene captures free radicals through its sulfide group and aromatic fused ring structure, thereby inhibiting the thermal oxidative degradation of the polystyrene chain, thereby imparting good aging resistance to the material. Modified polystyrene, modified silica, and modified silicone oil are melt-blended and hot-pressed to create a flame-retardant packaging material. The cavity structure of the thiacalixarene in the modified polystyrene side chain forms a host-guest complex with the quaternary ammonium salt on the modified silicone oil. The modified silicone oil acts as a crosslinker to form a dynamic crosslinked network, significantly improving the material's tensile strength.

[0032] Test Example 3: Flame retardant performance test: Test Method: Flame retardancy was tested using a JF-3 Limiting Oxygen Index Tester manufactured by the Nanjing Jiangning District Analytical Instrument Factory. Test samples were cut into 100 mm × 6.5 mm × 3 mm dimensions. Testing was conducted in accordance with GB / T 2406. Results are shown in Table 3.

[0033] Table 3 From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 3, it can be found that the material prepared by the present invention has good flame retardant properties.

[0034] The flame retardancy of Examples 1 to 3 is better than that of the comparative example; this indicates that the surface of the pretreated silica contains a large number of amino groups, which can be grafted with mono-6-O-(p-toluenesulfonyl)-β-cyclodextrin. β-cyclodextrin, as an environmentally friendly carbon-forming agent, reacts with phosphoric acid and urea through the remaining hydroxyl structure at high temperature to form nitrogen-phosphorus-doped phosphates, which catalyze the formation of a dense expanded carbon layer during combustion, achieving condensed phase flame retardancy by isolating oxygen and blocking heat transfer.

[0035] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be encompassed therein. Any reference in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A method for preparing a flame retardant packaging material, characterized in that: The method comprises the following preparation steps: (1) reacting thiacalixarene and allyl chloride to obtain monosubstituted vinylthiacalixarene; grafting monosubstituted vinylthiacalixarene onto polystyrene to obtain modified polystyrene; (2) reacting N-methyloctylamine and allyl chloride to obtain vinyl tertiary amine; reacting hydrogenated silicone oil and vinyl tertiary amine to obtain terminal tertiary amine silicone oil; (3) Reacting tertiary amine-terminated silicone oil and chloropropane to obtain modified silicone oil; (4) reacting 3-aminopropyltriethoxysilane and nano-silica to obtain pretreated nano-silica; reacting mono-6-O-(p-toluenesulfonyl)-β-cyclodextrin and pre-treated silica to obtain pre-modified silica; (5) reacting pre-modified silica, phosphoric acid, and urea to obtain modified silica; (6) The modified polystyrene, modified silica and modified silicone oil are melt-blended and hot-pressed to obtain a flame-retardant packaging material.

2. The method for preparing a flame retardant packaging material according to claim 1, characterized in that: The preparation method of the modified polystyrene in step (1) is as follows: monosubstituted vinylthiacalixarene, polystyrene, and dibenzoyl peroxide are reacted at 70-80° C. for 35-40 hours to obtain modified polystyrene; the mass ratio of polystyrene, monosubstituted vinylthiacalixarene, and dibenzoyl peroxide is 1:(0.1-0.2):(0.006-0.008).

3. The method for preparing a flame retardant packaging material according to claim 2, characterized in that: The preparation method of the monosubstituted vinyl thiacalixarene comprises: mixing thiacalixarene, triethylamine, potassium iodide, and tetrahydrofuran, heating the mixture to 55-60° C. and refluxing for 30-40 minutes, adding allyl chloride, and reacting the mixture under reflux for 4-5 days to obtain the monosubstituted vinyl thiacalixarene; the molar ratio of thiacalixarene, allyl chloride, triethylamine, and potassium iodide is 1:(1.3-1.5):(1.5-2.0):(0.08-0.1), and the mass ratio of thiacalixarene to tetrahydrofuran is 1:(20-30).

4. The method for preparing a flame retardant packaging material according to claim 1, characterized in that: The preparation method of the tertiary amine-terminated silicone oil in step (2) is as follows: hydrogen-containing silicone oil and vinyl tertiary amine are mixed, and a catalyst is added to react for 2-3 hours to obtain the tertiary amine-terminated silicone oil; the molar ratio of hydrogen-containing silicone oil to vinyl tertiary amine is 1:(2.1-2.3); and the mass of the catalyst is 0.001-0.002 times that of the hydrogen-containing silicone oil.

5. The method for preparing a flame retardant packaging material according to claim 4, characterized in that: The preparation method of the vinyl tertiary amine comprises: dissolving anhydrous potassium carbonate and N-methyloctylamine in acetonitrile, adding allyl chloride, heating to 55-65° C. and reacting for 6-8 hours to obtain the vinyl tertiary amine; the molar ratio of N-methyloctylamine, allyl chloride, and anhydrous potassium carbonate is (1.3-1.5):1:(1.2-1.5); and the mass of acetonitrile is 10-12 times that of N-methyloctylamine.

6. The method for preparing a flame retardant packaging material according to claim 1, characterized in that: The preparation method of the modified silicone oil in step (3) is as follows: tertiary amine-terminated silicone oil and chloropropane are mixed, and the mixture is reacted at 60-70° C. for 14-16 hours to obtain the modified silicone oil; the molar ratio of the tertiary amine-terminated silicone oil to the chloropropane is 1:(2.1-2.3).

7. The method for preparing a flame retardant packaging material according to claim 1, characterized in that: The preparation method of the pre-modified silica in step (4) is as follows: hydrolyzing 3-aminopropyltriethoxysilane to obtain a hydrolyzed silane coupling agent; dispersing nano-silica in anhydrous ethanol, adding the hydrolyzed silane coupling agent, heating to 70-80°C and reacting for 2-3 hours to obtain pretreated nano-silica; the mass ratio of nano-silica, anhydrous ethanol, and 3-aminopropyltriethoxysilane is 1:(10-12):(0.1-0.3); Mono-6-O-(p-toluenesulfonyl)-β-cyclodextrin, pretreated silica, N-methylpyrrolidone, and potassium iodide are reacted at 70-80°C for 6-7 hours to obtain pre-modified silica; the mass ratio of pretreated silica, mono-6-O-(p-toluenesulfonyl)-β-cyclodextrin, N-methylpyrrolidone, and potassium iodide is 1:(0.6-0.8):(30-40):(0.02-0.03).

8. The method for preparing a flame retardant packaging material according to claim 1, characterized in that: The preparation method of the modified silica in step (5) is as follows: pre-modified silica, phosphoric acid, and urea are heated to 80-85°C and reacted for 3-4 hours, and then the remaining urea is added and the reaction is continued for 2-3 hours to obtain modified silica; the mass ratio of pre-modified silica, phosphoric acid, and urea is 1:(1.2-1.5):(1.7-2.0).

9. The method for preparing a flame retardant packaging material according to claim 1, characterized in that: The method for preparing the flame-retardant packaging material in step (6) is as follows: melt-blending and tableting modified polystyrene, modified silicon dioxide, and modified silicone oil to obtain the flame-retardant packaging material.

10. A flame retardant packaging material prepared according to the method for preparing a flame retardant packaging material according to any one of claims 1 to 9.

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