Fresh-keeping foam box for cold chain turnover and preparation method of fresh-keeping foam box

Abstract

The invention relates to the field of cold-chain logistics packaging, in particular to a fresh-keeping foam box for cold-chain turnover and a preparation method of the fresh-keeping foam box, and aims at solving the problems that an existing fresh-keeping foam box is limited in heat insulation performance and poor in antibacterial effect. According to the preparation method, polystyrene is used as a main raw material, then heat-insulating antibacterial particles are added into the polystyrene, the heat-insulating performance of the fresh-keeping foam box can be remarkably improved, the heat-insulating antibacterial particles have good adsorption performance and can adsorb moisture and peculiar smells in the foam box, meanwhile, the heat-insulating antibacterial particles have antibacterial and fresh-keeping effects, and the heat-insulating performance of the fresh-keeping foam box is improved. Growth of bacteria and mould can be inhibited, deterioration of articles is prevented, and the shelf life of the articles is prolonged; by using the fresh-keeping foam box, the temperature stability, sanitation and safety of goods in the transportation process are ensured, and the risk of cold chain breakage and the possibility of microbial contamination are reduced, so that the safety and reliability of cold-chain logistics are greatly improved, the food safety is ensured, and the requirements of modern cold-chain transportation are met.

Description

Technical Field

[0001] The invention relates to the field of cold chain logistics packaging, and in particular to a fresh-keeping foam box for cold chain turnover and a preparation method thereof. Background Art

[0002] With the improvement of people's living standards and the rapid development of e-commerce, the demand for fresh food, medicines and other items that need to be stored at low temperatures is increasing. Cold chain logistics refers to a systematic project in which refrigerated and frozen foods are always kept in a specified low-temperature environment in all links from production, storage, transportation, sales to consumption, in order to ensure food quality and reduce food loss. As an important means to ensure the quality and safety of these items, the development of cold chain logistics has also received more and more attention. As a commonly used packaging container in cold chain logistics, the performance of fresh-keeping foam boxes directly affects the preservation effect and quality of the packaged items. At present, the fresh-keeping foam boxes on the market generally have the disadvantages of limited thermal insulation performance and poor antibacterial effect, which makes the temperature inside the foam box very easy to rise, causing product deterioration. In addition, the inner wall of the foam box is prone to bacteria, which poses a major hidden danger to the hygiene and safety of food and medicine, and it is difficult to meet the growing demand for cold chain logistics.

[0003] Therefore, developing a fresh-keeping foam box for cold chain turnover and a preparation method thereof is of great significance for improving the thermal insulation and antibacterial properties of cold chain logistics packaging. Summary of the invention

[0004] In order to overcome the above-mentioned technical problems, the purpose of the present invention is to provide a fresh-keeping foam box for cold chain turnover and a preparation method thereof, by adding polystyrene resin, heat-insulating and antibacterial particles, nano-calcium carbonate, a foaming agent and a cross-linking agent into a high-speed mixer and stirring and mixing to obtain a mixture, adding the mixture into a foaming machine for foaming and molding, and then cooling to obtain a fresh-keeping foam box for cold chain turnover, thereby solving the problems of limited thermal insulation performance and poor antibacterial effect of existing fresh-keeping foam boxes.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A fresh-keeping foam box for cold chain turnover, comprising the following components in parts by weight:

[0007] 70-80 parts of polystyrene resin, 4-16 parts of heat-insulating antibacterial particles, 2-6 parts of nano calcium carbonate, 1.5-5.5 parts of foaming agent and 0.5-1.5 parts of cross-linking agent;

[0008] The heat-insulating antibacterial particles are prepared by the following steps:

[0009] Step A1: adding natural sepiolite fiber and hydrochloric acid solution into a three-necked flask equipped with a stirrer and a thermometer, stirring the mixture for 20-30 minutes at a temperature of 25-30° C. and a stirring rate of 300-400 r / min, then heating the mixture to 80-85° C. and continuing to stir the mixture for 6-8 hours. After the reaction is completed, the reaction product is cooled to room temperature, then centrifuged, and the precipitate is washed with distilled water for 2-3 times, then placed in a vacuum drying oven, and dried for 2-3 hours at a temperature of 120-130° C. to obtain pretreated sepiolite fiber;

[0010] Step A2: Tetraethoxysilane, anhydrous ethanol and deionized water are added to a three-necked flask equipped with a stirrer, a thermometer and a constant pressure dropping funnel, and stirred for 20-30 minutes at a temperature of 25-30°C and a stirring rate of 300-400 r / min, and then γ-glycidyloxypropyltrimethoxysilane is added dropwise while stirring, and the dropping rate is controlled to 1-2 drops / s. After the addition is completed, the pH is adjusted to 3-3.5 with hydrochloric acid solution, and then the temperature is raised to 60-6 The reaction was continued under stirring at 5°C for 2-3h, and then the pretreated sepiolite fiber was added and the reaction was continued under stirring for 30-60min. After the reaction was completed, the reaction product was cooled to room temperature, and then the pH was adjusted to 7.5-8 with ammonia water, and then the gel was allowed to stand, and then aged at a temperature of 45-50°C for 20-30h, and then the gel was immersed in n-hexane for 10-15h, and then placed in a vacuum drying oven, and dried at a temperature of 60-65°C for 2-3h to obtain a composite aerogel;

[0011] Step A3: Add zinc acetate and deionized water to a three-necked flask equipped with a stirrer and a thermometer, stir and react for 20-30 minutes at a temperature of 25-30°C and a stirring rate of 300-400r / min, then adjust the pH to 10-11 with a sodium hydroxide solution, then add the composite aerogel and continue to stir and react for 30-50 minutes at a temperature of 50-55°C, then continue to stir and react for 6-8 hours at a temperature of 160-165°C, and after the reaction is completed, cool the reaction product to room temperature, then centrifuge, wash the precipitate with distilled water and anhydrous ethanol for 2-3 times in sequence, then place it in a vacuum drying oven, and dry it at a temperature of 60-65°C for 2-3 hours to obtain a supported aerogel;

[0012] Step A4: Add the supported aerogel, polyethyleneimine and deionized water to a three-necked flask equipped with a stirrer and a thermometer, stir and react for 20-30 minutes at a temperature of 25-30°C and a stirring rate of 300-400r / min, then heat to 50-55°C and continue stirring and reacting for 20-30 minutes, then heat to 120-125°C and continue stirring and reacting for 3-5 hours, after the reaction is completed, cool the reaction product to room temperature, then centrifuge, wash the precipitate with distilled water and anhydrous ethanol for 2-3 times in sequence, then place it in a vacuum drying oven, and dry it at a temperature of 50-55°C for 2-3 hours to obtain a polyamine-modified aerogel;

[0013] Step A5: Add polyamine-modified aerogel and anhydrous methanol to a three-necked flask equipped with a stirrer and a thermometer, and ultrasonically disperse them at an ultrasonic frequency of 40-50kHz for 20-30min, then add benzyl chloride and continue ultrasonically dispersing for 10-15min, and then stir the reaction at a temperature of 65-70°C and a stirring rate of 300-400r / min for 3-4h. After the reaction, cool the reaction product to room temperature, centrifuge it, wash the precipitate with anhydrous ethanol for 2-3 times, and then place it in a vacuum drying oven and dry it at a temperature of 70-75°C for 5-6h to obtain thermal insulating antibacterial particles.

[0014] As a further solution of the present invention: the usage ratio of the natural sepiolite fiber and the hydrochloric acid solution in step A1 is 1 g: 10-15 mL.

[0015] As a further solution of the present invention: the molar concentration of the hydrochloric acid solution in step A1 is 1-2 mol / L.

[0016] As a further solution of the present invention: the usage ratio of the tetraethoxysilane, anhydrous ethanol, deionized water, γ-glycidyloxypropyltrimethoxysilane and pretreated sepiolite fiber in step A2 is 10 mmol: 25-30 mL: 5-9 mL: 0.1-0.3 g: 0.2-0.8 g.

[0017] As a further solution of the present invention: the molar concentration of the hydrochloric acid solution in step A2 is 0.5-1 mol / L; the molar concentration of the ammonia water is 1-2 mol / L.

[0018] As a further solution of the present invention: the usage ratio of the zinc acetate, deionized water and composite aerogel in step A3 is 3-7 g: 80-100 mL: 10 g.

[0019] As a further solution of the present invention: the mass fraction of the sodium hydroxide solution in step A3 is 15-20%.

[0020] As a further solution of the present invention: the usage ratio of the supported aerogel, polyethyleneimine and deionized water in step A4 is 5g:0.2-1.6g:50-60mL.

[0021] As a further solution of the present invention: the polyethyleneimine in step A4 is a branched polyethyleneimine with an average weight average molecular weight Mw=800.

[0022] As a further solution of the present invention: the usage ratio of the polyamine-modified aerogel, anhydrous methanol and benzyl chloride in step A5 is 5 g: 50-60 mL: 1-10 g.

[0023] As a further solution of the present invention: a method for preparing a fresh-keeping foam box for cold chain turnover, comprising the following steps:

[0024] Step 1: Weigh 70-80 parts of polystyrene resin, 4-16 parts of heat-insulating antibacterial particles, 2-6 parts of nano calcium carbonate, 1.5-5.5 parts of foaming agent and 0.5-1.5 parts of cross-linking agent according to weight, and set aside;

[0025] Step 2: Add polystyrene resin, heat-insulating antibacterial particles, nano calcium carbonate, foaming agent and cross-linking agent into a high-speed mixer, and stir and mix for 10-30 minutes at a stirring speed of 1000-1500 r / min to obtain a mixture;

[0026] Step three: Add the mixture into a foaming machine, foam it at a foaming temperature of 100-120°C and a foaming pressure of 0.5-1.0MPa, and then cool it to obtain a fresh-keeping foam box for cold chain turnover.

[0027] As a further solution of the present invention: the foaming agent is one of n-pentane, isopentane and cyclopentane.

[0028] As a further solution of the present invention: the cross-linking agent is one of divinylbenzene, diethylenetriamine and dicumyl peroxide.

[0029] Beneficial effects of the present invention:

[0030] The invention discloses a fresh-keeping foam box for cold chain turnover and a preparation method thereof. The method comprises the following steps: adding polystyrene resin, heat-insulating antibacterial particles, nano-calcium carbonate, a foaming agent and a cross-linking agent into a high-speed mixer and stirring and mixing to obtain a mixture, adding the mixture into a foaming machine for foaming and forming, and then cooling to obtain a fresh-keeping foam box for cold chain turnover. The preparation method uses polystyrene as a main raw material, and then adding the heat-insulating antibacterial particles thereto, which can significantly improve the heat-insulating performance of the fresh-keeping foam box, effectively reduce the influence of the external temperature on the articles in the box, and extend the fresh-keeping period of the articles. The heat-insulating antibacterial particles have good adsorption performance, can absorb moisture and odor in the foam box, and keep the environment in the box dry and clean. At the same time, the heat-insulating antibacterial particles have antibacterial and fresh-keeping effects, can inhibit the growth of bacteria and molds, prevent the articles from deteriorating, and extend the fresh-keeping period of the articles. The use of the fresh-keeping foam box ensures the temperature stability and sanitary safety of the goods during transportation, reduces the risk of cold chain severance and the possibility of microbial contamination, thereby greatly improving the safety and reliability of cold chain logistics, ensuring food safety, and meeting the needs of modern cold chain transportation.

[0031] In the process of preparing the fresh-keeping foam box for cold chain turnover, the heat-insulating and antibacterial particles are firstly treated with a hydrochloric acid solution to dissolve the impurities of the natural sepiolite fiber, effectively increase the pore size of the natural sepiolite fiber, and increase the microporosity to obtain the pretreated sepiolite fiber. Then, tetraethoxysilane is used as a raw material to form a silica aerogel. The use of γ-glycidyloxypropyltrimethoxysilane can graft epoxy groups thereto, and the silica aerogel is supported by the pretreated sepiolite fiber to obtain a composite aerogel. Then, zinc acetate is used as a raw material to load zinc oxide in the pores of the composite aerogel to obtain a loaded aerogel. Then, the loaded aerogel is treated with polyethyleneimine. The amino groups on the polyethyleneimine react with the epoxy groups on the loaded aerogel to introduce a large number of tertiary amine groups to obtain a polyamine-modified aerogel. Finally, the polyamine-modified aerogel and chlorinated Benzyl reaction, the chlorine atoms on the benzyl chloride react with the tertiary amine groups on the polyamine-modified aerogel to form a large number of quaternary ammonium groups, and obtain heat-insulating antibacterial particles; the silica aerogel has the excellent properties of high specific surface area, high porosity and low thermal conductivity, which makes it have excellent thermal insulation and adsorption effects, effectively blocking heat transfer while absorbing moisture and odor in the foam box. The use of sepiolite fiber to support the silica aerogel can effectively prevent the silica aerogel from shrinking, collapsing and cracking, and make the composite aerogel have both mechanical strength and thermal insulation properties. The loaded zinc oxide is an important metal inorganic antibacterial agent, which can slowly release free positively charged zinc ions, electrostatically adsorb and destroy the negatively charged cell wall to achieve an antibacterial effect, and after introducing a large number of quaternary ammonium groups, its antibacterial properties can be further improved, which can inhibit the growth of bacteria and mold and prevent items from deteriorating. DETAILED DESCRIPTION

[0032] 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 described embodiments 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 creative work are within the scope of protection of the present invention.

[0033] Embodiment 1:

[0034] This embodiment is a method for preparing a fresh-keeping foam box for cold chain turnover, comprising the following steps:

[0035] Step S1: 1 g of natural sepiolite fiber and 10 mL of a hydrochloric acid solution with a molar concentration of 1 mol / L are added to a three-necked flask equipped with a stirrer and a thermometer, and the mixture is stirred for reaction at a temperature of 25° C. and a stirring rate of 300 r / min for 20 min, and then the mixture is heated to 80° C. and the stirring reaction is continued for 6 h. After the reaction is completed, the reaction product is cooled to room temperature, and then centrifuged. The precipitate is washed twice with distilled water, and then placed in a vacuum drying oven and dried at a temperature of 120° C. for 2 h to obtain pretreated sepiolite fiber;

[0036] Step S2: 10 mmol of tetraethoxysilane, 25 mL of anhydrous ethanol and 5 mL of deionized water were added to a three-necked flask equipped with a stirrer, a thermometer and a constant pressure dropping funnel, and the mixture was stirred at a temperature of 25°C and a stirring rate of 300 r / min for 20 min. Then, 0.1 g of γ-glycidyloxypropyltrimethoxysilane was added dropwise while stirring, and the dropping rate was controlled to be 1 drop / s. After the addition was completed, a hydrochloric acid solution with a molar concentration of 0.5 mol / L was used to adjust the pH to 3, then heated to 60°C and continued to stir and react for 2h, then added 0.2g pretreated sepiolite fiber and continued to stir and react for 30min, after the reaction was completed, the reaction product was cooled to room temperature, then adjusted to pH 7.5 with ammonia water with a molar concentration of 1mol / L, then allowed to stand for gelation, then aged at 45°C for 20h, then immersed in n-hexane for 10h, then placed in a vacuum drying oven, and dried at 60°C for 2h to obtain a composite aerogel;

[0037] Step S3: 3 g of zinc acetate and 80 mL of deionized water were added to a three-necked flask equipped with a stirrer and a thermometer, and the mixture was stirred for 20 min at a temperature of 25 ° C and a stirring rate of 300 r / min. Then, the pH was adjusted to 10 with a 15% mass fraction of sodium hydroxide solution, and then 10 g of composite aerogel was added and the mixture was heated to 50 ° C and stirred for 30 min, and then heated to 160 ° C and stirred for 6 h. After the reaction was completed, the reaction product was cooled to room temperature, and then centrifuged. The precipitate was washed twice with distilled water and anhydrous ethanol in turn, and then placed in a vacuum drying oven and dried at 60 ° C for 2 h to obtain a supported aerogel;

[0038] Step S4: 5 g of supported aerogel, 0.2 g of branched polyethyleneimine with an average weight average molecular weight Mw=800 and 50 mL of deionized water were added to a three-necked flask equipped with a stirrer and a thermometer, and stirred for reaction at a temperature of 25°C and a stirring rate of 300 r / min for 20 min, then heated to 50°C and continued to stir for 20 min, then heated to 120°C and continued to stir for 3 h, and after the reaction was completed, the reaction product was cooled to room temperature, then centrifuged, and the precipitate was washed twice with distilled water and anhydrous ethanol in sequence, and then placed in a vacuum drying oven and dried at a temperature of 50°C for 2 h to obtain a polyamine-modified aerogel;

[0039] Step S5: 5 g of polyamine-modified aerogel and 50 mL of anhydrous methanol were added to a three-necked flask equipped with a stirrer and a thermometer, and ultrasonically dispersed for 20 min at an ultrasonic frequency of 40 kHz, and then 1 g of benzyl chloride was added and ultrasonically dispersed for 10 min, and then stirred for 3 h at a temperature of 65° C. and a stirring rate of 300 r / min. After the reaction was completed, the reaction product was cooled to room temperature and then centrifuged. The precipitate was washed twice with anhydrous ethanol, and then placed in a vacuum drying oven and dried at a temperature of 70° C. for 5 h to obtain heat-insulating antibacterial particles;

[0040] Step S6: 70 parts of polystyrene resin, 4 parts of heat-insulating antibacterial particles, 2 parts of nano-calcium carbonate, 1.5 parts of foaming agent and 0.5 parts of cross-linking agent are weighed according to weight and set aside; the foaming agent is n-pentane; the cross-linking agent is divinylbenzene;

[0041] Step S7: adding polystyrene resin, heat-insulating antibacterial particles, nano-calcium carbonate, foaming agent and cross-linking agent into a high-speed mixer, stirring and mixing at a stirring speed of 1000 r / min for 10 minutes to obtain a mixture;

[0042] Step S8: adding the mixture into a foaming machine, foaming and molding the mixture at a foaming temperature of 100° C. and a foaming pressure of 0.5 MPa, and then cooling the mixture to obtain a fresh-keeping foam box for cold chain turnover.

[0043] Embodiment 2:

[0044] This embodiment is a method for preparing a fresh-keeping foam box for cold chain turnover, comprising the following steps:

[0045] Step S1: 1 g of natural sepiolite fiber and 12 mL of a hydrochloric acid solution with a molar concentration of 1.5 mol / L are added to a three-necked flask equipped with a stirrer and a thermometer, and the mixture is stirred at 28° C. and a stirring rate of 350 r / min for 25 min, and then the mixture is heated to 82° C. and stirred for 7 h. After the reaction is completed, the reaction product is cooled to room temperature, and then centrifuged. The precipitate is washed twice with distilled water, and then placed in a vacuum drying oven and dried at 125° C. for 2.5 h to obtain pretreated sepiolite fiber;

[0046] Step S2: 10 mmol of tetraethoxysilane, 28 mL of anhydrous ethanol and 7 mL of deionized water were added to a three-necked flask equipped with a stirrer, a thermometer and a constant pressure dropping funnel, and the mixture was stirred for 25 min at a temperature of 28° C. and a stirring rate of 350 r / min. Then, 0.2 g of γ-glycidyloxypropyltrimethoxysilane was added dropwise while stirring, and the dropping rate was controlled to be 1 drop / s. After the addition was completed, the pH was adjusted to 3 with a hydrochloric acid solution having a molar concentration of 0.8 mol / L. Then, the mixture was heated to 62°C and stirred for 2.5 hours, 0.5 g of pretreated sepiolite fiber was added and stirred for 45 minutes, and the reaction product was cooled to room temperature after the reaction was completed. Then, the pH value was adjusted to 7.5 with 1.5 mol / L ammonia water, and the gel was allowed to stand. Then, the gel was aged at 48°C for 25 hours, and then the gel was immersed in n-hexane for 12 hours. Then, the gel was placed in a vacuum drying oven and dried at 62°C for 2.5 hours to obtain a composite aerogel.

[0047] Step S3: 5 g of zinc acetate and 90 mL of deionized water were added to a three-necked flask equipped with a stirrer and a thermometer, and the mixture was stirred for 25 min at a temperature of 28 ° C and a stirring rate of 350 r / min. Then, the pH was adjusted to 10.5 with a sodium hydroxide solution having a mass fraction of 18%. Then, 10 g of the composite aerogel was added and the mixture was heated to 52 ° C and stirred for 40 min. Then, the mixture was heated to 162 ° C and stirred for 7 h. After the reaction was completed, the reaction product was cooled to room temperature and then centrifuged. The precipitate was washed twice with distilled water and anhydrous ethanol in sequence, and then placed in a vacuum drying oven and dried at 62 ° C for 2.5 h to obtain a supported aerogel.

[0048] Step S4: 5 g of supported aerogel, 0.9 g of branched polyethyleneimine with an average weight average molecular weight Mw=800 and 55 mL of deionized water were added to a three-necked flask equipped with a stirrer and a thermometer, and stirred for reaction at a temperature of 28° C. and a stirring rate of 350 r / min for 25 min, then heated to 52° C. and continued to stir for reaction for 25 min, then heated to 122° C. and continued to stir for reaction for 4 h, and after the reaction was completed, the reaction product was cooled to room temperature, then centrifuged, and the precipitate was washed twice with distilled water and anhydrous ethanol in sequence, and then placed in a vacuum drying oven and dried at a temperature of 52° C. for 2.5 h to obtain a polyamine-modified aerogel;

[0049] Step S5: 5 g of polyamine-modified aerogel and 55 mL of anhydrous methanol were added to a three-necked flask equipped with a stirrer and a thermometer, and ultrasonically dispersed for 25 min at an ultrasonic frequency of 45 kHz, and then 5.5 g of benzyl chloride was added to continue ultrasonic dispersion for 12 min, and then stirred for 3.5 h at a temperature of 68 ° C and a stirring rate of 350 r / min. After the reaction was completed, the reaction product was cooled to room temperature and then centrifuged. The precipitate was washed twice with anhydrous ethanol, and then placed in a vacuum drying oven and dried at a temperature of 72 ° C for 5.5 h to obtain heat-insulating antibacterial particles;

[0050] Step S6: weigh 75 parts of polystyrene resin, 10 parts of heat-insulating antibacterial particles, 4 parts of nano-calcium carbonate, 3.5 parts of foaming agent and 1 part of cross-linking agent according to weight, and set aside; the foaming agent is isopentane; the cross-linking agent is diethylenetriamine;

[0051] Step S7: adding polystyrene resin, heat-insulating antibacterial particles, nano-calcium carbonate, foaming agent and cross-linking agent into a high-speed mixer, stirring and mixing at a stirring speed of 1250 r / min for 20 minutes to obtain a mixture;

[0052] Step S8: adding the mixture into a foaming machine, foaming and molding the mixture at a foaming temperature of 110° C. and a foaming pressure of 0.8 MPa, and then cooling the mixture to obtain a fresh-keeping foam box for cold chain turnover.

[0053] Embodiment 3:

[0054] This embodiment is a method for preparing a fresh-keeping foam box for cold chain turnover, comprising the following steps:

[0055] Step S1: 1 g of natural sepiolite fiber and 15 mL of a hydrochloric acid solution with a molar concentration of 2 mol / L are added to a three-necked flask equipped with a stirrer and a thermometer, and the mixture is stirred at a temperature of 30° C. and a stirring rate of 400 r / min for 30 min, and then the mixture is heated to 85° C. and the stirring reaction is continued for 8 h. After the reaction is completed, the reaction product is cooled to room temperature, and then centrifuged. The precipitate is washed with distilled water for 3 times, and then placed in a vacuum drying oven and dried at a temperature of 130° C. for 3 h to obtain pretreated sepiolite fiber;

[0056] Step S2: 10 mmol of tetraethoxysilane, 30 mL of anhydrous ethanol and 9 mL of deionized water were added to a three-necked flask equipped with a stirrer, a thermometer and a constant pressure dropping funnel, and the mixture was stirred at a temperature of 30°C and a stirring rate of 400 r / min for 30 min. Then, 0.3 g of γ-glycidyloxypropyltrimethoxysilane was added dropwise while stirring, and the dropping rate was controlled to 2 drops / s. After the addition was completed, a hydrochloric acid solution with a molar concentration of 1 mol / L was used to adjust the pH to 3.5, then the temperature was raised to 65°C and the reaction was continued under stirring for 3 hours, then 0.8 g of pretreated sepiolite fiber was added and the reaction was continued under stirring for 60 minutes, and the reaction product was cooled to room temperature after the reaction was completed, and then the pH was adjusted to 8 with ammonia water with a molar concentration of 2 mol / L, and then the gel was allowed to stand, and then aged at a temperature of 50°C for 30 hours, and then the gel was immersed in n-hexane for 15 hours, and then placed in a vacuum drying oven and dried at a temperature of 65°C for 3 hours to obtain a composite aerogel;

[0057] Step S3: 7 g of zinc acetate and 100 mL of deionized water were added to a three-necked flask equipped with a stirrer and a thermometer, and the mixture was stirred for 30 min at a temperature of 30 ° C and a stirring rate of 400 r / min. Then, the pH was adjusted to 11 with a 20% mass fraction of sodium hydroxide solution, and then 10 g of composite aerogel was added and the mixture was heated to 55 ° C and continued to stir for 50 min. Then, the mixture was heated to 165 ° C and continued to stir for 8 h. After the reaction was completed, the reaction product was cooled to room temperature and then centrifuged. The precipitate was washed with distilled water and anhydrous ethanol three times in sequence, and then placed in a vacuum drying oven and dried at 65 ° C for 3 h to obtain a supported aerogel.

[0058] Step S4: 5 g of supported aerogel, 1.6 g of branched polyethyleneimine with an average weight average molecular weight Mw=800 and 60 mL of deionized water were added to a three-necked flask equipped with a stirrer and a thermometer, and stirred for reaction at a temperature of 30° C. and a stirring rate of 400 r / min for 30 min, then heated to 55° C. and continued to stir for reaction for 30 min, then heated to 125° C. and continued to stir for reaction for 5 h, and after the reaction was completed, the reaction product was cooled to room temperature, then centrifuged, and the precipitate was washed 3 times with distilled water and anhydrous ethanol in sequence, and then placed in a vacuum drying oven and dried at a temperature of 55° C. for 3 h to obtain a polyamine-modified aerogel;

[0059] Step S5: 5 g of polyamine-modified aerogel and 60 mL of anhydrous methanol were added to a three-necked flask equipped with a stirrer and a thermometer, and ultrasonically dispersed for 30 min at an ultrasonic frequency of 50 kHz, and then 10 g of benzyl chloride was added and ultrasonically dispersed for 15 min, and then stirred for 4 h at a temperature of 70° C. and a stirring rate of 400 r / min. After the reaction was completed, the reaction product was cooled to room temperature and then centrifuged. The precipitate was washed 3 times with anhydrous ethanol, and then placed in a vacuum drying oven and dried at a temperature of 75° C. for 6 h to obtain heat-insulating antibacterial particles;

[0060] Step S6: 80 parts of polystyrene resin, 16 parts of heat-insulating antibacterial particles, 6 parts of nano-calcium carbonate, 5.5 parts of foaming agent and 1.5 parts of cross-linking agent are weighed according to weight and set aside; the foaming agent is cyclopentane; the cross-linking agent is diisopropylbenzene peroxide;

[0061] Step S7: adding polystyrene resin, heat-insulating antibacterial particles, nano-calcium carbonate, foaming agent and cross-linking agent into a high-speed mixer, stirring and mixing at a stirring speed of 1500 r / min for 30 minutes to obtain a mixture;

[0062] Step S8: adding the mixture into a foaming machine, foaming and molding the mixture at a foaming temperature of 120° C. and a foaming pressure of 1.0 MPa, and then cooling the mixture to obtain a fresh-keeping foam box for cold chain turnover.

[0063] Comparative Example 1:

[0064] This comparative example is a method for preparing a fresh-keeping foam box for cold chain turnover, comprising the following steps:

[0065] Step S1: 80 parts of polystyrene resin, 6 parts of nano calcium carbonate, 5.5 parts of foaming agent and 1.5 parts of cross-linking agent are weighed according to weight and set aside; the foaming agent is cyclopentane; the cross-linking agent is diisopropylbenzene peroxide;

[0066] Step S2: adding polystyrene resin, nano calcium carbonate, foaming agent and cross-linking agent into a high-speed mixer, stirring and mixing at a stirring speed of 1500 r / min for 30 minutes to obtain a mixture;

[0067] Step S3: adding the mixture into a foaming machine, foaming and molding the mixture at a foaming temperature of 120° C. and a foaming pressure of 1.0 MPa, and then cooling the mixture to obtain a fresh-keeping foam box for cold chain turnover.

[0068] Comparative Example 2:

[0069] This comparative example is a method for preparing a fresh-keeping foam box for cold chain turnover, comprising the following steps:

[0070] Step S1: 1 g of natural sepiolite fiber and 15 mL of a hydrochloric acid solution with a molar concentration of 2 mol / L are added to a three-necked flask equipped with a stirrer and a thermometer, and the mixture is stirred at a temperature of 30° C. and a stirring rate of 400 r / min for 30 min, and then the mixture is heated to 85° C. and the stirring reaction is continued for 8 h. After the reaction is completed, the reaction product is cooled to room temperature, and then centrifuged. The precipitate is washed with distilled water for 3 times, and then placed in a vacuum drying oven and dried at a temperature of 130° C. for 3 h to obtain pretreated sepiolite fiber;

[0071] Step S2: 10 mmol of tetraethoxysilane, 30 mL of anhydrous ethanol and 9 mL of deionized water were added to a three-necked flask equipped with a stirrer, a thermometer and a constant pressure dropping funnel, and the mixture was stirred at a temperature of 30°C and a stirring rate of 400 r / min for 30 min. Then, 0.3 g of γ-glycidyloxypropyltrimethoxysilane was added dropwise while stirring, and the dropping rate was controlled to 2 drops / s. After the addition was completed, a hydrochloric acid solution with a molar concentration of 1 mol / L was used to adjust the pH to 3.5, then the temperature was raised to 65°C and the reaction was continued under stirring for 3 hours, then 0.8 g of pretreated sepiolite fiber was added and the reaction was continued under stirring for 60 minutes, and the reaction product was cooled to room temperature after the reaction was completed, and then the pH was adjusted to 8 with ammonia water with a molar concentration of 2 mol / L, and then the gel was allowed to stand, and then aged at a temperature of 50°C for 30 hours, and then the gel was immersed in n-hexane for 15 hours, and then placed in a vacuum drying oven and dried at a temperature of 65°C for 3 hours to obtain a composite aerogel;

[0072] Step S3: 80 parts of polystyrene resin, 16 parts of composite aerogel, 6 parts of nano calcium carbonate, 5.5 parts of foaming agent and 1.5 parts of cross-linking agent are weighed according to weight and set aside; the foaming agent is cyclopentane; the cross-linking agent is diisopropylbenzene peroxide;

[0073] Step S4: adding polystyrene resin, composite aerogel, nano calcium carbonate, foaming agent and cross-linking agent into a high-speed mixer, stirring and mixing at a stirring speed of 1500 r / min for 30 minutes to obtain a mixture;

[0074] Step S5: adding the mixture into a foaming machine, foaming and molding the mixture at a foaming temperature of 120° C. and a foaming pressure of 1.0 MPa, and then cooling the mixture to obtain a fresh-keeping foam box for cold chain turnover.

[0075] Comparative Example 3:

[0076] This comparative example is a method for preparing a fresh-keeping foam box for cold chain turnover, comprising the following steps:

[0077] Step S1: 1 g of natural sepiolite fiber and 15 mL of a hydrochloric acid solution with a molar concentration of 2 mol / L are added to a three-necked flask equipped with a stirrer and a thermometer, and the mixture is stirred at a temperature of 30° C. and a stirring rate of 400 r / min for 30 min, and then the mixture is heated to 85° C. and the stirring reaction is continued for 8 h. After the reaction is completed, the reaction product is cooled to room temperature, and then centrifuged. The precipitate is washed with distilled water for 3 times, and then placed in a vacuum drying oven and dried at a temperature of 130° C. for 3 h to obtain pretreated sepiolite fiber;

[0078] Step S2: 10 mmol of tetraethoxysilane, 30 mL of anhydrous ethanol and 9 mL of deionized water were added to a three-necked flask equipped with a stirrer, a thermometer and a constant pressure dropping funnel, and the mixture was stirred at a temperature of 30°C and a stirring rate of 400 r / min for 30 min. Then, 0.3 g of γ-glycidyloxypropyltrimethoxysilane was added dropwise while stirring, and the dropping rate was controlled to 2 drops / s. After the addition was completed, a hydrochloric acid solution with a molar concentration of 1 mol / L was used to adjust the pH to 3.5, then the temperature was raised to 65°C and the reaction was continued under stirring for 3 hours, then 0.8 g of pretreated sepiolite fiber was added and the reaction was continued under stirring for 60 minutes, and the reaction product was cooled to room temperature after the reaction was completed, and then the pH was adjusted to 8 with ammonia water with a molar concentration of 2 mol / L, and then the gel was allowed to stand, and then aged at a temperature of 50°C for 30 hours, and then the gel was immersed in n-hexane for 15 hours, and then placed in a vacuum drying oven and dried at a temperature of 65°C for 3 hours to obtain a composite aerogel;

[0079] Step S3: 7 g of zinc acetate and 100 mL of deionized water were added to a three-necked flask equipped with a stirrer and a thermometer, and the mixture was stirred for 30 min at a temperature of 30 ° C and a stirring rate of 400 r / min. Then, the pH was adjusted to 11 with a 20% mass fraction of sodium hydroxide solution, and then 10 g of composite aerogel was added and the mixture was heated to 55 ° C and continued to stir for 50 min. Then, the mixture was heated to 165 ° C and continued to stir for 8 h. After the reaction was completed, the reaction product was cooled to room temperature and then centrifuged. The precipitate was washed with distilled water and anhydrous ethanol three times in sequence, and then placed in a vacuum drying oven and dried at 65 ° C for 3 h to obtain a supported aerogel.

[0080] Step S4: 80 parts of polystyrene resin, 16 parts of supported aerogel, 6 parts of nano calcium carbonate, 5.5 parts of foaming agent and 1.5 parts of cross-linking agent are weighed according to weight and set aside; the foaming agent is cyclopentane; the cross-linking agent is diisopropylbenzene peroxide;

[0081] Step S5: adding polystyrene resin, supported aerogel, nano calcium carbonate, foaming agent and cross-linking agent into a high-speed mixer, stirring and mixing at a stirring speed of 1500 r / min for 30 minutes to obtain a mixture;

[0082] Step S6: adding the mixture into a foaming machine, foaming and molding the mixture at a foaming temperature of 120° C. and a foaming pressure of 1.0 MPa, and then cooling the mixture to obtain a fresh-keeping foam box for cold chain turnover.

[0083] The performance of the cold chain turnover fresh-keeping foam boxes of Examples 1-3 and Comparative Examples 1-3 were tested, and the test results are shown in the following table:

[0084] Referring to the data in the above table, based on the comparison between Examples 1-3 and Comparative Examples 1-3, it can be seen that adding thermal insulation and antibacterial particles can give the cold chain turnover fresh-keeping foam box excellent thermal insulation and antibacterial properties.

[0085] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0086] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined in this application, they shall all fall within the protection scope of the present invention.

Claims

1. A fresh-keeping foam box for cold chain turnover, characterized in that: It comprises the following components in parts by weight: 70-80 parts of polystyrene resin, 4-16 parts of heat-insulating antibacterial particles, 2-6 parts of nano calcium carbonate, 1.5-5.5 parts of foaming agent and 0.5-1.5 parts of cross-linking agent; The heat-insulating antibacterial particles are prepared by the following steps: Step A1: stirring the natural sepiolite fiber and the hydrochloric acid solution to react, cooling the reaction product after the reaction is completed, and then centrifuging it, washing and drying the precipitate to obtain the pretreated sepiolite fiber; Step A2: Tetraethoxysilane, anhydrous ethanol and deionized water are stirred for reaction, and then γ-glycidyloxypropyltrimethoxysilane is added dropwise while stirring, and after the addition is completed, the pH is adjusted with a hydrochloric acid solution, and then the pretreated sepiolite fiber is added and continued to stir and react. After the reaction is completed, the reaction product is cooled, and then the pH is adjusted with ammonia water, and then the gel is allowed to stand for aging, and then the gel is immersed in n-hexane and then dried to obtain a composite aerogel; Step A3: stirring zinc acetate and deionized water to react, then adjusting the pH with sodium hydroxide solution, then adding the composite aerogel and continuing to stir the reaction, cooling the reaction product after the reaction is completed, then centrifuging, washing and drying the precipitate to obtain a supported aerogel; Step A4: stirring the supported aerogel, polyethyleneimine and deionized water for reaction, cooling the reaction product after the reaction is completed, and then centrifuging it, washing and drying the precipitate to obtain a polyamine-modified aerogel; Step A5: Ultrasonic dispersion of polyamine-modified aerogel and anhydrous methanol, then adding benzyl chloride to continue ultrasonic dispersion, followed by stirring reaction, cooling the reaction product after the reaction, then centrifuging, washing and drying the precipitate to obtain heat-insulating antibacterial particles.

2. A cold chain turnover fresh-keeping foam box according to claim 1, characterized in that: The usage ratio of the natural sepiolite fiber and the hydrochloric acid solution in step A1 is 1 g: 10-15 mL; the molar concentration of the hydrochloric acid solution is 1-2 mol / L.

3. A fresh-keeping foam box for cold chain turnover according to claim 1, characterized in that: The dosage ratio of the tetraethoxysilane, anhydrous ethanol, deionized water, γ-glycidyloxypropyltrimethoxysilane and pretreated sepiolite fiber in step A2 is 10mmol:25-30mL:5-9mL:0.1-0.3g:0.2-0.8g; the molar concentration of the hydrochloric acid solution is 0.5-1mol / L; and the molar concentration of the ammonia water is 1-2mol / L.

4. A fresh-keeping foam box for cold chain turnover according to claim 1, characterized in that: The usage ratio of the zinc acetate, deionized water and composite aerogel in step A3 is 3-7 g: 80-100 mL: 10 g; the mass fraction of the sodium hydroxide solution is 15-20%.

5. A fresh-keeping foam box for cold chain turnover according to claim 1, characterized in that: The amount ratio of the supported aerogel, polyethyleneimine and deionized water in step A4 is 5g:0.2-1.6g:50-60mL; the polyethyleneimine is a branched polyethyleneimine with an average weight average molecular weight Mw=800.

6. A fresh-keeping foam box for cold chain turnover according to claim 1, characterized in that: The usage ratio of the polyamine-modified aerogel, anhydrous methanol and benzyl chloride in step A5 is 5 g: 50-60 mL: 1-10 g.

7. A method for preparing a fresh-keeping foam box for cold chain turnover, characterized in that: The following steps are involved: Step 1: Weigh 70-80 parts of polystyrene resin, 4-16 parts of heat-insulating antibacterial particles, 2-6 parts of nano calcium carbonate, 1.5-5.5 parts of foaming agent and 0.5-1.5 parts of cross-linking agent according to weight, and set aside; Step 2: Add polystyrene resin, heat-insulating antibacterial particles, nano calcium carbonate, foaming agent and cross-linking agent into a high-speed mixer, and stir and mix for 10-30 minutes at a stirring speed of 1000-1500 r / min to obtain a mixture; Step three: Add the mixture into a foaming machine, foam it at a foaming temperature of 100-120°C and a foaming pressure of 0.5-1.0MPa, and then cool it to obtain a fresh-keeping foam box for cold chain turnover.

8. The method for preparing a fresh-keeping foam box for cold chain turnover according to claim 7, characterized in that: The foaming agent is one of n-pentane, isopentane and cyclopentane.

9. The method for preparing a fresh-keeping foam box for cold chain turnover according to claim 7, characterized in that: The crosslinking agent is one of divinylbenzene, diethylenetriamine and dicumyl peroxide.

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