A sealed plastic box and its processing technology

Abstract

This application relates to the field of plastic processing technology, specifically disclosing a sealed plastic box and its processing technology. The sealed plastic box of this application consists of a box body and a sealing cap; both the box body and the sealing cap are made of a polypropylene composition; and the raw materials of the polypropylene composition include modified polypropylene, a cyclodextrin-boehmite complex, a toughening agent, and a compatibilizer. The processing technology of the sealed plastic box of this application includes the following steps: first, the modified polypropylene, the cyclodextrin-boehmite complex, the toughening agent, and the compatibilizer are mixed evenly to obtain a premix; then, the premix is ​​melted and granulated to obtain a polypropylene composition; finally, the polypropylene composition is placed in a mold and injection molded to obtain a box body and a sealing cap, which are then combined to form a sealed plastic box. The sealed plastic box of this application has excellent anti-aging properties and mechanical properties, and can protect food for a long time.

Description

Technical Field

[0001] This application relates to the field of plastic processing technology, and more specifically, to a sealed plastic box and its processing technology. Background Technology

[0002] In daily life, sealed plastic boxes are commonly used for food packaging, greatly improving the convenience of taking food out. Currently, sealed plastic boxes are mainly made of polymer materials such as polyethylene and polypropylene. Among them, polypropylene (PP) is a general-purpose thermoplastic with excellent comprehensive performance, possessing advantages such as light weight, high strength, chemical corrosion resistance, low cost, and recyclability. However, because PP material contains tertiary carbon atoms, it is very sensitive to heat and oxygen, and is extremely prone to oxidative degradation, leading to a decrease in the mechanical properties of PP material. Consequently, the lifespan of sealed plastic boxes is relatively short, requiring periodic replacement.

[0003] Existing anti-aging PP sealing plastic boxes typically incorporate anti-aging agents and antioxidants during the manufacturing process. These agents continuously absorb active free radicals generated within the plastic due to external factors, thereby reducing molecular breakage or recombination and delaying plastic aging. However, the poor compatibility between these agents and PP leads to a decrease in the mechanical properties of PP material. These problems significantly limit the further application and development of PP materials in sealing plastic boxes. Therefore, there is an urgent need to propose a new sealing plastic box and its processing technology to solve the problems of easy aging and decreased mechanical properties in existing sealing plastic boxes. This would allow PP to maintain good mechanical properties while improving its anti-aging performance, enabling the sealing plastic box to protect food for a longer period. Summary of the Invention

[0004] To address the problems of easy aging and decreased mechanical properties of existing sealed plastic boxes, this application provides a sealed plastic box and its processing technology.

[0005] Firstly, this application provides a sealed plastic box, employing the following technical solution:

[0006] A sealed plastic box, comprising a box body and a sealing lid; both the box body and the sealing lid are made of a polypropylene composition.

[0007] The polypropylene composition comprises the following raw materials in parts by weight: 40-80 parts modified polypropylene, 8-10 parts cyclodextrin-boehmite complex, 4-5 parts toughening agent, and 1-3 parts compatibilizer.

[0008] The modified polypropylene is prepared by reacting polypropylene with a grafting solution after plasma treatment.

[0009] By adopting the above technical solution, the sealed plastic box of this application consists of a box body and a sealing cap, both made of polypropylene composition, which has good sealing effect and anti-aging properties. Furthermore, the raw materials of the polypropylene composition of this application include modified polypropylene, cyclodextrin-boehmite complex, toughening agent, and compatibilizer, and the weight proportions of each substance are controlled within a certain range, effectively solving the problem of easy aging and decreased mechanical properties of the sealed plastic box, resulting in superior performance and expanding its application range.

[0010] Preferably, the modified polypropylene is prepared by the following method:

[0011] First, the polypropylene is treated with plasma. The plasma treatment conditions are as follows: after evacuation, argon gas is introduced at a flow rate of 20-40 cm³. 3 At a power of 40-80KW, a voltage of 380V, and a processing time of 240-300s, polypropylene is added to the grafting solution and heated in a water bath at a temperature of 60-80℃ for 2-4 hours. Finally, the mixture is filtered, washed, and dried to obtain modified polypropylene.

[0012] Preferably, the mass ratio of the polypropylene to the grafting solution is 1:2-3.

[0013] By adopting the above technical solution, this application uses plasma treatment of polypropylene and controls the plasma treatment conditions to make a large number of hydroxyl and carboxyl groups appear on the surface of polypropylene, which can react with the grafting solution. At the same time, by controlling the mass ratio of polypropylene to grafting solution and the grafting reaction conditions, the full reaction between polypropylene and grafting solution is promoted, resulting in a better grafting effect of polypropylene, which is beneficial to improving the anti-aging properties of polypropylene composition, thereby making the sealed plastic box have significant anti-aging properties.

[0014] Preferably, the polypropylene is obtained by mixing homopolymer polypropylene and copolymer polypropylene in a mass ratio of 2-4:5.

[0015] By adopting the above technical solution, the polypropylene of this application is obtained by mixing homopolymer polypropylene and copolymer polypropylene in a certain mass ratio; the molecular chain of homopolymer PP is relatively regular, while the regularity of the molecular chain of copolymer PP is disrupted by the ethylene chain segment. The two work together to maintain a good balance between toughness and rigidity in the polypropylene material, thereby making the mechanical properties of the sealed plastic box more excellent.

[0016] Preferably, the grafting solution is prepared by the following method:

[0017] By weight, take 10-30 parts cinnamic acid, 40-60 parts acetone, 0.1-0.3 parts tert-butyl peroxide benzoate, and 0.4-0.8 parts...

[0018] Sodium hexadecyl sulfate is mixed evenly to obtain a grafting solution.

[0019] By adopting the above technical solution, the raw materials of the grafting solution of this application include cinnamic acid, acetone, tert-butyl peroxide benzoate, and sodium hexadecyl sulfate. Cinnamic acid has strong antioxidant, anti-corrosion, and bactericidal effects. Modifying polypropylene with cinnamic acid can improve the anti-aging properties of polypropylene, enhance its bactericidal and anti-corrosion properties, and improve its compatibility with other components, thereby making the anti-aging properties of the sealed plastic box of this application better.

[0020] Preferably, the cyclodextrin-boehmite complex is prepared by the following method:

[0021] After grinding, boehmite is first treated with acid and then calcined to obtain pretreated boehmite. The pretreated boehmite, cyclodextrin, and diisopropyl peroxide are added to an ethanol aqueous solution, stirred and reacted for a period of time, filtered, and dried to obtain a cyclodextrin-boehmite complex.

[0022] Further, preferably, the cyclodextrin-boehmite complex is prepared by the following method:

[0023] Step A: Add boehmite to a 1 mol / L hydrochloric acid solution, ultrasonically disperse for 15-20 min, filter, dry, and calcine in a muffle furnace at 450-500℃ for 1-1.5 h to obtain pretreated boehmite.

[0024] Step B: Add the pretreated boehmite, cyclodextrin, and diisopropyl peroxide to a 20-40 wt% ethanol aqueous solution, stir at 50-60℃ and 400-600 r / min for 1-2 h, filter, and dry to obtain the cyclodextrin-boehmite complex.

[0025] Preferably, the cyclodextrin-boehmite complex comprises the following raw materials in parts by weight: 20-40 parts boehmite, 15-20 parts cyclodextrin, 0.6-1 part diisopropyl peroxide, 20-30 parts hydrochloric acid solution, and 100-200 parts aqueous ethanol solution.

[0026] Preferably, the cyclodextrin is carboxymethyl-β-cyclodextrin.

[0027] By adopting the above technical solution, the cyclodextrin-boehmite complex of this application utilizes cyclodextrin to encapsulate boehmite. After acid and high-temperature calcination treatment, a large number of active groups are generated on the surface of the boehmite, which can better interact with cyclodextrin. At the same time, by controlling various process parameters, the performance of the cyclodextrin-boehmite complex is made more stable. The addition of the cyclodextrin-boehmite complex in this application can improve the anti-aging performance and mechanical properties of the sealed plastic box. In addition, this application further prefers carboxymethyl-β-cyclodextrin, which is beneficial to promoting the connection between the cyclodextrin-boehmite complex and other components, making the structure of the sealed plastic box more compact and significantly enhancing its mechanical properties.

[0028] Preferably, the toughening agent is obtained by mixing epoxidized soybean oil and disproportionated rosin in a mass ratio of 3-6:2.

[0029] By adopting the above technical solution, the toughening agent of this application is obtained by mixing epoxidized soybean oil and disproportionated rosin. Both have significant toughening properties and good antioxidant properties. This application controls the mass ratio of the two within a certain range, and the two work synergistically to improve the flowability of modified polypropylene and enhance the mechanical properties of the polypropylene composition. This allows the anti-aging properties of the sealed plastic box to be improved while maintaining excellent mechanical properties.

[0030] Preferably, the compatibilizer is obtained by mixing polypropylene grafted with styrene and maleic anhydride grafted with polypropylene in a mass ratio of 7:4-8.

[0031] By adopting the above technical solution, this application uses a mixture of polypropylene grafted with styrene and maleic anhydride grafted with polypropylene as a compatibilizer, which effectively enhances the bonding force between the components in the polypropylene composition, thereby improving the overall performance of the sealed plastic box.

[0032] Secondly, this application provides a processing technology for a sealed plastic box, employing the following technical solution:

[0033] A processing method for a sealed plastic box includes the following steps:

[0034] First, the modified polypropylene, cyclodextrin-boehmite complex, toughening agent, and compatibilizer are mixed evenly to obtain a premix. Then, the premix is ​​melted and granulated to obtain a polypropylene composition. Finally, the polypropylene composition is placed in a mold and injection molded to obtain a box body and a sealing cap, which are then combined to form a sealed plastic box.

[0035] Preferably, the processing technology of the sealed plastic box includes the following steps:

[0036] S1. Mix the modified polypropylene, cyclodextrin-boehmite complex, toughening agent, and compatibilizer at a speed of 1000-2000 r / min for 5-10 min to obtain a premix.

[0037] S2. Add the premixed material to a twin-screw extruder, with a melt temperature of 170-220℃ and a screw speed of 400-600 r / min, and perform melt extrusion granulation to obtain a polypropylene composition;

[0038] S3. Place the polypropylene composition in a mold and perform injection molding at a temperature of 165-175℃ and an injection pressure of 50-70MPa to obtain a box body and a sealing cap, which are then combined to form a sealed plastic box.

[0039] By adopting the above technical solution, during the processing, the modified polypropylene, cyclodextrin-boehmite composite, toughening agent, and compatibilizer are fully and evenly dispersed by controlling various process parameters. By controlling the temperature and speed of the twin-screw extruder, as well as the injection temperature and pressure, the anti-aging performance and mechanical properties of the resulting sealed plastic box are enhanced. The processing technology of the sealed plastic box of this application is simple, low-cost, and optimizes the overall performance of the sealed plastic box.

[0040] In summary, this application has the following beneficial effects:

[0041] 1. The sealed plastic box of this application consists of a box body and a sealing cap; both the box body and the sealing cap are made of polypropylene composition. The raw materials of the polypropylene composition include modified polypropylene, cyclodextrin-boehmite complex, toughening agent and compatibilizer, which improves the anti-aging performance and mechanical properties of the sealed plastic box.

[0042] 2. The modified polypropylene of this application is obtained by grafting cinnamic acid onto polypropylene after plasma treatment; the introduction of cinnamic acid can not only improve the anti-aging properties of the sealed plastic box, but also enhance the bactericidal and anti-corrosion properties of the sealed plastic box.

[0043] 3. The addition of the cyclodextrin-boehmite complex in this application not only improves the anti-aging properties of the sealed plastic box, but also ensures that the sealed plastic box has excellent mechanical properties.

[0044] 4. The processing technology of the sealed plastic box of this application is simple, low-cost, and suitable for industrial production. The resulting sealed plastic box has better overall performance and can meet the high requirements of food packaging. Detailed Implementation

[0045] The present application will be further described in detail below with reference to the embodiments.

[0046] Preparation Examples 1-5 provide methods for preparing graft solutions.

[0047] Preparation Example 1

[0048] The grafting solution is prepared by the following method:

[0049] Take 100g of cinnamic acid, 400g of acetone, 1g of tert-butyl peroxide benzoate, and 4g of sodium hexadecyl sulfate, and mix them at 600r / min for 60min to obtain the grafting solution.

[0050] Preparation Example 2

[0051] The grafting solution is prepared by the following method:

[0052] Take 150g of cinnamic acid, 450g of acetone, 1.5g of tert-butyl peroxide benzoate, and 5g of sodium hexadecyl sulfate, and mix them at 700r / min for 50min to obtain the grafting solution.

[0053] Preparation Example 3

[0054] The grafting solution is prepared by the following method:

[0055] Take 200g of cinnamic acid, 500g of acetone, 2g of tert-butyl peroxide benzoate, and 6g of sodium hexadecyl sulfate, and mix them at 800r / min for 40min to obtain the grafting solution.

[0056] Preparation Example 4

[0057] The grafting solution is prepared by the following method:

[0058] Take 250g of cinnamic acid, 550g of acetone, 2.5g of tert-butyl peroxide benzoate, and 7g of sodium hexadecyl sulfate, and mix them at 900r / min for 30min to obtain the grafting solution.

[0059] Preparation Example 5

[0060] The grafting solution is prepared by the following method:

[0061] Take 300g of cinnamic acid, 600g of acetone, 3g of tert-butyl peroxide benzoate, and 8g of sodium hexadecyl sulfate, and mix them at 1000r / min for 20min to obtain the grafting solution.

[0062] Preparation Examples 6-10 and Comparative Preparation Examples 1-3 provide methods for preparing modified polypropylene.

[0063] Preparation Example 6

[0064] Modified polypropylene is prepared by the following method:

[0065] Take 100g of polypropylene, first treat it with plasma, then evacuate it and introduce argon gas at a flow rate of 20cm³. 3 / s, at a power of 40KW, a voltage of 380V, and a processing time of 240s; then add 200g of grafting solution to the polypropylene and treat it at a water bath temperature of 60℃ for 4h; filter, wash, and dry to obtain modified polypropylene.

[0066] The polypropylene was obtained by mixing homopolymer polypropylene and copolymer polypropylene in a mass ratio of 2:5; the grafting solution was prepared in Preparation Example 1.

[0067] Preparation Example 7

[0068] Modified polypropylene is prepared by the following method:

[0069] Take 100g of polypropylene, first treat it with plasma, then evacuate it and introduce argon gas at a flow rate of 25cm³. 3 / s, at a power of 50KW, a voltage of 380V, and a processing time of 250s; then polypropylene is added to 230g of grafting solution and treated at a water bath temperature of 65℃ for 3.5h; after filtration, washing, and drying, modified polypropylene is obtained.

[0070] In this process, polypropylene is obtained by mixing homopolymer polypropylene and copolymer polypropylene in a mass ratio of 1:2; the grafting solution is prepared in Preparation Example 2.

[0071] Preparation Example 8

[0072] Modified polypropylene is prepared by the following method:

[0073] Take 100g of polypropylene, first treat it with plasma, then evacuate it and introduce argon gas at a flow rate of 30cm³. 3 / s, at a power of 60KW, a voltage of 380V, and a processing time of 260s; then add polypropylene to 250g of grafting solution, treat at a water bath temperature of 70℃ for 3h; filter, wash, and dry to obtain modified polypropylene.

[0074] The polypropylene was obtained by mixing homopolymer polypropylene and copolymer polypropylene in a mass ratio of 3:5; the grafting solution was prepared in Preparation Example 3.

[0075] Preparation Example 9

[0076] Modified polypropylene is prepared by the following method:

[0077] Take 100g of polypropylene, treat it with plasma first, then evacuate it and introduce argon gas at a flow rate of 35cm³. 3 / s, at a power of 70KW, a voltage of 380V, and a processing time of 280s; then polypropylene is added to 280g of grafting solution and treated at a water bath temperature of 75℃ for 2.5h; then filtered, washed, and dried to obtain modified polypropylene.

[0078] In this process, polypropylene is obtained by mixing homopolymer polypropylene and copolymer polypropylene in a mass ratio of 7:10; the grafting solution is prepared in Preparation Example 4.

[0079] Preparation Example 10

[0080] Modified polypropylene is prepared by the following method:

[0081] Take 100g of polypropylene, first treat it with plasma, then evacuate it and introduce argon gas at a flow rate of 40cm³. 3 / s, at a power of 80KW, a voltage of 380V, and a processing time of 300s; then add 300g of grafting solution to the polypropylene and treat it in a water bath at 80℃ for 2h; filter, wash, and dry to obtain modified polypropylene.

[0082] In this process, polypropylene is obtained by mixing homopolymer polypropylene and copolymer polypropylene in a mass ratio of 4:5; the grafting solution is prepared in Preparation Example 5.

[0083] Comparative Preparation Example 1

[0084] Compared with Preparation Example 1, the only difference from Preparation Example 6 is that the polypropylene is only homopolymer polypropylene.

[0085] Comparative Preparation Example 2

[0086] Compared with Preparation Example 2, the only difference from Preparation Example 6 is that the polypropylene is only copolymer polypropylene.

[0087] Comparative preparation example 3

[0088] Compared with Preparation Example 3, the only difference from Preparation Example 6 is that the polypropylene was added directly to the grafting solution without undergoing plasma treatment.

[0089] Preparation Examples 11-15 provide cyclodextrin-boehmite complexes and their preparation methods.

[0090] Preparation Example 11

[0091] The cyclodextrin-boehmite complex comprises the following raw materials: 200g boehmite, 150g carboxymethyl-β-cyclodextrin, 6g diisopropyl peroxide, 200g hydrochloric acid solution, and 1000g ethanol aqueous solution.

[0092] The cyclodextrin-boehmite complex was prepared by the following method:

[0093] Step A: Add boehmite to a 1 mol / L hydrochloric acid solution, ultrasonically disperse for 15 min, filter, dry, and calcine in a muffle furnace at 400℃ for 2 h to obtain pretreated boehmite.

[0094] Step B: Add the pretreated boehmite, carboxymethyl-β-cyclodextrin, and diisopropyl peroxide to a 20wt% aqueous ethanol solution, stir at 45℃ and 400r / min for 2h, filter, and dry to obtain the cyclodextrin-boehmite complex.

[0095] Preparation Example 12

[0096] The cyclodextrin-boehmite complex comprises the following raw materials: 250g boehmite, 160g carboxymethyl-β-cyclodextrin, 7g diisopropyl peroxide, 220g hydrochloric acid solution, and 1200g ethanol aqueous solution.

[0097] The cyclodextrin-boehmite complex was prepared by the following method:

[0098] Step A: Add boehmite to a 1 mol / L hydrochloric acid solution, ultrasonically disperse for 16 min, filter, dry, and calcine in a muffle furnace at 420℃ for 1.8 h to obtain pretreated boehmite.

[0099] Step B: Add the pretreated boehmite, carboxymethyl-β-cyclodextrin, and diisopropyl peroxide to a 25wt% aqueous ethanol solution, stir at 48℃ and 450r / min for 1.8h, filter, and dry to obtain the cyclodextrin-boehmite complex.

[0100] Preparation Example 13

[0101] The cyclodextrin-boehmite complex comprises the following raw materials: 300g boehmite, 170g carboxymethyl-β-cyclodextrin, 8g diisopropyl peroxide, 250g hydrochloric acid solution, and 1500g ethanol aqueous solution.

[0102] The cyclodextrin-boehmite complex was prepared by the following method:

[0103] Step A: Add boehmite to a 1 mol / L hydrochloric acid solution, ultrasonically disperse for 18 min, filter, dry, and calcine in a muffle furnace at 450℃ for 1.5 h to obtain pretreated boehmite.

[0104] Step B: Add the pretreated boehmite, carboxymethyl-β-cyclodextrin, and diisopropyl peroxide to a 30wt% aqueous ethanol solution, stir at 50°C and 500 r / min for 1.5 h, filter, and dry to obtain the cyclodextrin-boehmite complex.

[0105] Preparation Example 14

[0106] The cyclodextrin-boehmite complex comprises the following raw materials: 300g boehmite, 190g carboxymethyl-β-cyclodextrin, 9g diisopropyl peroxide, 280g hydrochloric acid solution, and 1800g ethanol aqueous solution.

[0107] The cyclodextrin-boehmite complex was prepared by the following method:

[0108] Step A: Add boehmite to a 1 mol / L hydrochloric acid solution, ultrasonically disperse for 19 min, filter, dry, and calcine in a muffle furnace at 520℃ for 1.2 h to obtain pretreated boehmite;

[0109] Step B: Add the pretreated boehmite, carboxymethyl-β-cyclodextrin, and diisopropyl peroxide to a 35wt% aqueous ethanol solution, stir at 52℃ and 550r / min for 1.2h, filter, and dry to obtain the cyclodextrin-boehmite complex.

[0110] Preparation Example 15

[0111] The cyclodextrin-boehmite complex comprises the following raw materials: 400g boehmite, 200g carboxymethyl-β-cyclodextrin, 10g diisopropyl peroxide, 300g hydrochloric acid solution, and 2000g ethanol aqueous solution.

[0112] The cyclodextrin-boehmite complex was prepared by the following method:

[0113] Step A: Add boehmite to a 1 mol / L hydrochloric acid solution, ultrasonically disperse for 20 min, filter, dry, and calcine in a muffle furnace at 550℃ for 1 h to obtain pretreated boehmite.

[0114] Step B: Add the pretreated boehmite, carboxymethyl-β-cyclodextrin, and diisopropyl peroxide to a 40wt% aqueous ethanol solution, stir at 55℃ and 600r / min for 1h, filter, and dry to obtain the cyclodextrin-boehmite complex.

[0115] Examples 1-5 provide a sealed plastic box and its processing technology.

[0116] Example 1

[0117] A sealed plastic box, comprising a box body and a sealing lid; both the box body and the sealing lid are made of a polypropylene composition; the polypropylene composition includes the following raw materials: 4 kg modified polypropylene, 0.8 kg cyclodextrin-boehmite complex, 0.4 kg toughening agent, and 0.1 kg compatibilizer;

[0118] Among them, the modified polypropylene was prepared by Preparation Example 6; the cyclodextrin-boehmite complex was prepared by Preparation Example 11; the toughening agent was obtained by mixing epoxidized soybean oil and disproportionated rosin in a mass ratio of 3:2; and the compatibilizer was obtained by mixing polypropylene grafted with styrene and maleic anhydride grafted with polypropylene in a mass ratio of 7:4.

[0119] A processing method for a sealed plastic box includes the following steps:

[0120] S1. Modified polypropylene, cyclodextrin-boehmite complex, toughening agent, and compatibilizer are mixed at 1000 r / min for 10 min to obtain a premix.

[0121] S2. Add the premix to a twin-screw extruder, with a melt temperature of 170℃ and a screw speed of 400r / min, and perform melt extrusion granulation to obtain a polypropylene composition;

[0122] S3. Place the polypropylene composition in a mold and perform injection molding at a temperature of 165°C and a pressure of 50MPa to obtain a box body and a sealing cap, which are then combined to form a sealed plastic box.

[0123] Example 2

[0124] A sealed plastic box, comprising a box body and a sealing lid; both the box body and the sealing lid are made of a polypropylene composition; the polypropylene composition comprises the following raw materials: 5 kg modified polypropylene, 0.85 kg cyclodextrin-boehmite complex, 0.42 kg toughening agent, and 0.15 kg compatibilizer;

[0125] Among them, the modified polypropylene was prepared by Preparation Example 7; the cyclodextrin-boehmite complex was prepared by Preparation Example 12; the toughening agent was obtained by mixing epoxidized soybean oil and disproportionated rosin in a mass ratio of 2:1; and the compatibilizer was obtained by mixing polypropylene grafted with styrene and maleic anhydride grafted with polypropylene in a mass ratio of 7:5.

[0126] A processing method for a sealed plastic box includes the following steps:

[0127] S1. Modified polypropylene, cyclodextrin-boehmite complex, toughening agent, and compatibilizer are mixed at 1200 r / min for 8 min to obtain a premix.

[0128] S2. Add the premix to a twin-screw extruder, with a melt temperature of 180℃ and a screw speed of 450r / min, and perform melt extrusion granulation to obtain a polypropylene composition;

[0129] S3. Place the polypropylene composition in a mold and perform injection molding at a temperature of 168°C and an injection pressure of 55MPa to obtain a box body and a sealing cap, which are then combined to form a sealed plastic box.

[0130] Example 3

[0131] A sealed plastic box, comprising a box body and a sealing lid; both the box body and the sealing lid are made of a polypropylene composition; the polypropylene composition comprises the following raw materials: 6 kg modified polypropylene, 0.9 kg cyclodextrin-boehmite complex, 0.45 kg toughening agent, and 2 kg compatibilizer;

[0132] Among them, the modified polypropylene was prepared by Preparation Example 8; the cyclodextrin-boehmite complex was prepared by Preparation Example 13; the toughening agent was obtained by mixing epoxidized soybean oil and disproportionated rosin in a mass ratio of 5:2; and the compatibilizer was obtained by mixing polypropylene grafted with styrene and maleic anhydride grafted with polypropylene in a mass ratio of 7:6.

[0133] A processing method for a sealed plastic box includes the following steps:

[0134] S1. Modified polypropylene, cyclodextrin-boehmite complex, toughening agent and compatibilizer are mixed at 1500 r / min for 7 min to obtain premix.

[0135] S2. Add the premix to a twin-screw extruder, with a melt temperature of 200℃ and a screw speed of 500r / min, and perform melt extrusion granulation to obtain a polypropylene composition;

[0136] S3. Place the polypropylene composition in a mold and perform injection molding at a temperature of 170°C and a pressure of 60MPa to obtain a box body and a sealing cap, which are then combined to form a sealed plastic box.

[0137] Example 4

[0138] A sealed plastic box, comprising a box body and a sealing lid; both the box body and the sealing lid are made of a polypropylene composition.

[0139] A polypropylene composition comprising the following raw materials: 7 kg modified polypropylene, 0.95 kg cyclodextrin-boehmite complex, 0.48 kg toughening agent, and 0.25 kg compatibilizer;

[0140] Among them, the modified polypropylene was prepared by Preparation Example 9; the cyclodextrin-boehmite complex was prepared by Preparation Example 14; the toughening agent was obtained by mixing epoxidized soybean oil and disproportionated rosin in a mass ratio of 11:4; and the compatibilizer was obtained by mixing polypropylene grafted with styrene and maleic anhydride grafted with polypropylene in a mass ratio of 1:1.

[0141] A processing method for a sealed plastic box includes the following steps:

[0142] S1. Modified polypropylene, cyclodextrin-boehmite complex, toughening agent, and compatibilizer are mixed at 1800 r / min for 6 min to obtain a premix.

[0143] S2. Add the premix to a twin-screw extruder, with a melt temperature of 200℃ and a screw speed of 550 r / min, and perform melt extrusion granulation to obtain a polypropylene composition;

[0144] S3. Place the polypropylene composition in a mold and perform injection molding at a temperature of 172°C and an injection pressure of 65MPa to obtain a box body and a sealing cap, which are then combined to form a sealed plastic box.

[0145] Example 5

[0146] A sealed plastic box, comprising a box body and a sealing lid; both the box body and the sealing lid are made of a polypropylene composition.

[0147] A polypropylene composition comprising the following raw materials: 8 kg modified polypropylene, 1 kg cyclodextrin-boehmite complex, 0.5 kg toughening agent, and 0.3 kg compatibilizer;

[0148] The modified polypropylene was prepared in Preparation Example 10; the cyclodextrin-boehmite complex was prepared in Preparation Example 15; the toughening agent was prepared by mixing epoxidized soybean oil and disproportionated rosin in a mass ratio of 3:1; and the compatibilizer was prepared by mixing polypropylene grafted with styrene and maleic anhydride grafted with polypropylene in a mass ratio of 7:8.

[0149] A processing method for a sealed plastic box includes the following steps:

[0150] S1. Modified polypropylene, cyclodextrin-boehmite complex, toughening agent, and compatibilizer are mixed at 2000 r / min for 5 min to obtain a premix.

[0151] S2. Add the premix to a twin-screw extruder, with a melt temperature of 220℃ and a screw speed of 600 r / min, and perform melt extrusion granulation to obtain a polypropylene composition;

[0152] S3. Place the polypropylene composition in a mold and perform injection molding at a temperature of 175°C and a pressure of 70MPa to obtain a box body and a sealing cap, which are then combined to form a sealed plastic box.

[0153] To verify the performance of the sealed plastic box provided in this application, the applicant has set up comparative examples 1-13, wherein: Comparative example 1

[0154] Comparative Example 1 is the same as Example 1, except that the modified polypropylene was prepared from Comparative Preparation Example 1.

[0155] Comparative Example 2

[0156] Comparative Example 2 is the same as Example 1, except that the modified polypropylene was prepared from Comparative Preparation Example 2.

[0157] Comparative Example 3

[0158] Comparative Example 3 is the same as Example 1, except that the modified polypropylene was prepared from Comparative Preparation Example 3.

[0159] Comparative Example 4

[0160] Comparative Example 4 is the same as Example 1, except that the modified polypropylene is replaced with an equal mass of polypropylene.

[0161] Comparative Example 5

[0162] Comparative Example 5 is the same as Example 1, except that the cyclodextrin-boehmite complex is replaced with an equal mass of boehmite.

[0163] Comparative Example 6

[0164] Comparative Example 6 is the same as Example 1, except that the cyclodextrin-boehmite complex is replaced with an equal mass of carboxymethyl-β-cyclodextrin.

[0165] Comparative Example 7

[0166] Comparative Example 7 is the same as Example 1, except that no cyclodextrin-boehmite complex is added.

[0167] Comparative Example 8

[0168] Comparative Example 8 is the same as Example 1, except that the toughening agent is only epoxidized soybean oil.

[0169] Comparative Example 9

[0170] Comparative Example 9 is the same as Example 1, except that the toughening agent is only disproportionated rosin.

[0171] Comparative Example 10

[0172] Comparative Example 10 is the same as Example 1, except that no toughening agent is added.

[0173] Comparative Example 11

[0174] Comparative Example 11 is the same as Example 1, except that the compatibilizer is only polypropylene grafted with styrene.

[0175] Comparative Example 12

[0176] Comparative Example 12 is the same as Example 1, except that the compatibilizer is only maleic anhydride-grafted polypropylene.

[0177] Comparative Example 13

[0178] Comparative Example 13 is the same as Example 1, except that no compatibilizer is added.

[0179] The main performance parameters of the sealed plastic boxes in Examples 1-5 and Comparative Examples 1-13 were obtained as follows, as detailed in Table 1:

[0180] The thermo-oxidative aging test of the sealed plastic box was carried out in accordance with GB / T 7141-2008 "Test Method for Thermal Aging of Plastics". The thermo-oxidative aging test chamber type was selected by method B, and the thermo-oxidative aging temperature and time were set to 90℃ and 0-500h, respectively.

[0181] The tensile strength of the sealed plastic box was tested in accordance with GB / T 1040.2-2006 "Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics".

[0182] The impact strength of the sealed plastic box was tested in accordance with GB / T 1043.1-2008 "Determination of impact properties of simply supported plastic beams - Part 1: Non-instrumental impact test".

[0183] Table 1:

[0184]

[0185]

[0186] As shown in Table 1 above, the sealed plastic boxes prepared in Examples 1-5 of this application have a much better overall performance than the sealed plastic boxes prepared in Comparative Examples 1-13. They have excellent anti-aging properties and significant mechanical properties, which enable the sealed plastic boxes to protect food for a long time.

[0187] As can be seen from Example 1 and Comparative Examples 1 and 2, the modified polypropylene in Example 1 was prepared by Preparation Example 6, and the polypropylene in Preparation Example 6 was obtained by mixing homopolymer polypropylene and copolymer polypropylene. Compared with Comparative Examples 1 and 2, the sealed plastic box obtained in Example 1 has better anti-aging properties and mechanical properties.

[0188] As can be seen from Example 1 and Comparative Examples 3 and 4: Example 1 uses modified polypropylene, and the modified polypropylene is prepared by Preparation Example 6. After plasma treatment, cinnamic acid is grafted onto the polypropylene. Compared with Comparative Examples 3 and 4, the anti-aging performance of the sealed plastic box obtained in Example 1 is significantly improved, while maintaining high tensile strength and impact strength.

[0189] As can be seen from Example 1 and Comparative Examples 5-7, the cyclodextrin-boehmite complex used in Example 1 has better anti-aging properties and mechanical properties than Comparative Examples 5-7.

[0190] As can be seen from Example 1 and Comparative Examples 8-10, the toughening agent used in Example 1 is obtained by mixing epoxidized soybean oil and disproportionated rosin. Compared with Comparative Examples 8-10, the overall performance of the sealed plastic box obtained in Example 1 is better than that of Comparative Examples 8-10.

[0191] As can be seen from Example 1 and Comparative Examples 11-13, the compatibilizer used in Example 1 is a mixture of polypropylene grafted with styrene and maleic anhydride grafted with polypropylene. Compared with Comparative Examples 11-13, the sealed plastic box obtained in Example 1 has better performance and can better protect food.

[0192] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A sealed plastic box, characterized in that, The sealed plastic box consists of a box body and a sealing lid; both the box body and the sealing lid are made of polypropylene composition. The polypropylene composition comprises the following raw materials in parts by weight: 40-80 parts modified polypropylene, 8-10 parts cyclodextrin-boehmite complex, 4-5 parts toughening agent, and 1-3 parts compatibilizer. The toughening agent is obtained by mixing epoxidized soybean oil and disproportionated rosin in a mass ratio of 3-6:2; The modified polypropylene is prepared by reacting polypropylene with a grafting solution after plasma treatment. The modified polypropylene is prepared by the following method: First, the polypropylene is treated with plasma. The plasma treatment conditions are: after evacuation, argon gas is introduced at a flow rate of 20-40 cm³. 3 At a power of 40-80KW, a voltage of 380V, and a processing time of 240-300s, polypropylene is added to the grafting solution and heated in a water bath at a temperature of 60-80℃ for 2-4 hours. Finally, the mixture is filtered, washed, and dried to obtain modified polypropylene. The grafting solution is prepared by the following method: by weight, 10-30 parts of cinnamic acid, 40-60 parts of acetone, 0.1-0.3 parts of tert-butyl peroxide benzoate, and 0.4-0.8 parts of sodium hexadecyl sulfate are mixed evenly to obtain the grafting solution. The polypropylene is obtained by mixing homopolymer polypropylene and copolymer polypropylene in a mass ratio of 2-4:

5.

2. The sealed plastic box according to claim 1, characterized in that, The mass ratio of the polypropylene to the grafting solution is 1:2-3.

3. The sealed plastic box according to claim 1, characterized in that, The cyclodextrin-boehmite complex was prepared by the following method: After grinding, boehmite is first treated with acid and then calcined to obtain pretreated boehmite. The pretreated boehmite, cyclodextrin, and diisopropyl peroxide are added to an ethanol aqueous solution, stirred and reacted for a period of time, filtered, and dried to obtain a cyclodextrin-boehmite complex.

4. The sealed plastic box according to claim 3, characterized in that, The cyclodextrin-boehmite complex comprises the following raw materials in parts by weight: 20-40 parts boehmite, 15-20 parts cyclodextrin, 0.6-1 part diisopropyl peroxide, 20-30 parts hydrochloric acid solution, and 100-200 parts aqueous ethanol solution.

5. The sealed plastic box according to claim 1, characterized in that, The compatibilizer is obtained by mixing polypropylene grafted with styrene and maleic anhydride grafted with polypropylene in a mass ratio of 7:4-8.

6. A processing method for a sealed plastic box according to any one of claims 1-5, characterized in that, Includes the following steps: First, the modified polypropylene, cyclodextrin-boehmite complex, toughening agent, and compatibilizer are mixed evenly to obtain a premix. Then, the premix is ​​melted and granulated to obtain a polypropylene composition. Finally, the polypropylene composition is placed in a mold and injection molded to obtain a box body and a sealing cap, which are then combined to form a sealed plastic box.

7. The processing technology of the sealed plastic box according to claim 6, characterized in that, Includes the following steps: S1. Mix the modified polypropylene, cyclodextrin-boehmite complex, toughening agent, and compatibilizer at a speed of 1000-2000 r / min for 5-10 min to obtain a premix. S2. Add the premixed material to a twin-screw extruder, with a melt temperature of 170-220℃ and a screw speed of 400-600 r / min, and perform melt extrusion granulation to obtain a polypropylene composition; S3. Place the polypropylene composition in a mold and perform injection molding at a temperature of 165-175℃ and an injection pressure of 50-70MPa to obtain a box body and a sealing cap, which are then combined to form a sealed plastic box.

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