High-barrier sealed waterproof multi-layer container bag for food and preparation method of high-barrier sealed waterproof multi-layer container bag

Abstract

The invention belongs to the technical field of flexible freight bags, and particularly relates to a high-barrier sealed waterproof multilayer food flexible freight bag and a preparation method thereof. The multi-layer container bag for food comprises an antibacterial inner layer, a barrier middle layer and a waterproof outer layer, the antibacterial inner layer comprises titanium dioxide modified aramid pulp coated with polyethylene and a chitosan intercalation dihydroxy compound in a mass ratio of (10-15): 1; the barrier middle layer comprises an ethylene-vinyl alcohol copolymer, an ethylene-vinyl acetate copolymer and erucic acid modified nano silicon dioxide in a mass ratio of (86-93): (5-10): (2-4); and the waterproof outer layer comprises polypropylene. The container bag provided by the invention has excellent antibacterial, puncture-resistant, barrier and waterproof functions, can be used as an inner bag of the container bag for food, is used for transporting and storing food, and prolongs the shelf life of the food.

Description

Technical Field

[0001] The invention belongs to the technical field of container bags, and in particular relates to a high-barrier, sealed and waterproof multi-layer food container bag and a preparation method thereof. Background Art

[0002] Container bags, also known as packaging bags, are more space-saving than barrels and boxes, thus reducing transportation and storage costs. Therefore, they are widely used in the fields of grain, chemical powder, cement manufacturing, and are now gradually entering the food and pharmaceutical industries. The packaging form of container bags has evolved from a single outer bag to a functional container bag with an inner bag. The requirements for the inner bag of a food container bag are more stringent than those for conventional container bags. In addition to having the good mechanical properties of conventional container bags and not being easily damaged during transportation, the materials used also need to have good antibacterial properties to prevent food from being contaminated, and to block oxygen and water vapor to extend the shelf life of food.

[0003] In the prior art, a Chinese patent with publication number CN115896974A discloses a high-strength tear-resistant woven container bag and a preparation method thereof. The high-strength tear-resistant woven container bag comprises woven wire, and the woven wire comprises the following materials by weight: 10-20 parts of reinforcing masterbatch, 1-5 parts of polyethylene and 75-89 parts of polypropylene, the reinforcing masterbatch comprises a filler, and the filler comprises at least one of nano calcium carbonate, talcum powder, and glass micropowder, and the reinforcing masterbatch also comprises waste rubber powder, and the filler is a filler modified by a modifier, and the modifier is selected from any one of stearic acid, calcium stearate, boric acid ester, and chlorinated paraffin. The container bag of this technical solution can be used to carry powdered and granular items such as food, grain, and medicine, and has the advantages of high strength, tear resistance, and long service life. However, the technical solution focuses on the outer bag form of the container bag. If only the outer bag is used, due to its woven structure and good air permeability, the shelf life of the food may be affected.

[0004] A Chinese patent with the publication number CN115339197A discloses a preparation method of a high-barrier anti-expansion packaging bag, which consists of the following steps: Step 1, select the preparation materials for the inner layer, middle layer, and outer layer of the packaging bag and conduct preliminary treatment; Step 2, make the inner membrane layer; Step 3, make the middle anti-expansion filling layer; Step 4, make the outer packaging layer; Step 5, compound and sew the inner layer, middle layer, and outer layer. This technical solution selects PVDC (polyvinylidene chloride) material as the inner membrane material of the high-barrier anti-expansion packaging bag, which has shrinkage, oxygen barrier, and water barrier properties and does not decompose under microwave heating conditions. Select PE (polyethylene) and EVOH (ethylene-vinyl alcohol copolymer) as the middle filling materials, which have good tensile properties and are suitable for packaging with a larger volume; EVOH (ethylene-vinyl alcohol copolymer) has good oxygen barrier properties. Using multiple polymers to make the packaging bag further improves the barrier properties of the packaging bag and expands the scope of application of the packaging bag. However, this technical solution uses polyvinylidene chloride as the inner membrane material, and the cost of polyvinylidene chloride is relatively high. Summary of the Invention

[0005] In view of the above problems, the present invention provides a high-barrier, sealed, and waterproof multi-layer food shipping bag and its preparation method. By using specific antibacterial inner layer raw materials, barrier intermediate layer raw materials, and waterproof outer layer raw materials, the shipping bag has excellent antibacterial, puncture-resistant, barrier, and waterproof functions, can be used as the inner bag of a food shipping bag for the transportation and storage of food, and improves the shelf life of food.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] In the first aspect of the present invention, there is provided a high-barrier, sealed, and waterproof multi-layer food shipping bag, including an antibacterial inner layer, a barrier intermediate layer, and a waterproof outer layer;

[0008] The antibacterial inner layer includes polyethylene and titanium dioxide-modified aramid pulp coated with chitosan intercalated dihydroxy compound in a mass ratio of 10-15:1;

[0009] The barrier intermediate layer includes ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, and erucic acid-modified nano-silica in a mass ratio of 86-93:5-10:2-4;

[0010] The waterproof outer layer includes polypropylene.

[0011] In some preferred embodiments, the polyethylene includes low-density polyethylene and linear low-density polyethylene in a mass ratio of 1:3-5.

[0012] Preferably, the melt flow rate of the low-density polyethylene is 3-5 g / 10 min (190 °C / 2.16 kg), preferably 4 g / 10 min (190 °C / 2.16 kg), grade: Anteo TM FK1820.

[0013] Preferably, the melt flow rate of the linear low-density polyethylene is 1-2 g / 10 min (190 °C / 2.16 kg), preferably 1.5 g / 10 min (190 °C / 2.16 kg), grade: Sinopec Maoming 2426K.

[0014] In some preferred embodiments, the preparation method of the titanium dioxide modified aramid pulp: Mix tetrabutyl titanate and the ethanol dispersion of aramid pulp evenly, heat and react, and after the reaction, wash and dry to obtain.

[0015] Preferably, the fiber length of the aramid pulp is 0.65-1.05 mm, purchased from Yantai Taihexing Material Technology Co., Ltd., model: 1628.

[0016] Preferably, the mass ratio of tetrabutyl titanate to aramid pulp is 1:2-3, preferably 1:2.5.

[0017] Preferably, the mass concentration of the ethanol dispersion of the aramid pulp is 10-30%, preferably 20%.

[0018] More preferably, the preparation method of the titanium dioxide modified aramid pulp: Mix tetrabutyl titanate and the ethanol dispersion of aramid pulp evenly, carry out heating reaction at 60-80 °C for 2-4 h, and after the reaction, wash and dry to obtain.

[0019] In some preferred embodiments, the preparation method of the titanium dioxide modified aramid pulp coated with chitosan intercalated dihydroxy compound: Mix magnesium nitrate, aluminum nitrate, urea, titanium dioxide modified aramid pulp and water evenly, heat and react, filter, and dry to obtain the titanium dioxide modified aramid pulp coated with dihydroxy compound; add it to the chitosan solution, heat and stir, filter, and dry to obtain.

[0020] The present invention creatively prepares titanium dioxide-modified aramid pulp coated with chitosan intercalated double-hydroxyl compound. First, the aramid pulp is modified with titanium dioxide, then the titanium dioxide-modified aramid pulp is coated with double-hydroxyl compound, and finally chitosan is intercalated between the layers of the double-hydroxyl compound. It is found that, compared with the single titanium dioxide-modified aramid pulp and chitosan intercalated double-hydroxyl compound, the antibacterial property, puncture resistance and barrier property of the flexible intermediate bulk container are synergistically improved. It is speculated that: titanium dioxide on the surface of aramid pulp not only exerts its own antibacterial property, but also is dispersed on the surface of aramid pulp to form a micro-nano rough structure, which is conducive to being coated by double-hydroxyl compound; the coating of double-hydroxyl compound on titanium dioxide-modified aramid pulp avoids the agglomeration of titanium dioxide, prolongs its activity, and at the same time, its parallel structure of lamellae can avoid the penetration of gas; meanwhile, chitosan is intercalated between the layers of double-hydroxyl compound, which not only realizes the slow release of chitosan, improves antibacterial property, but also chitosan fills the space between the layers of double-hydroxyl compound, further improving the densified structure, improving barrier property and enhancing interfacial strength, and reducing stress concentration.

[0021] In addition, the inventor of the present invention also found that when the aramid pulp is replaced with glass fiber, the puncture resistance and barrier property of the flexible intermediate bulk container decrease. It is speculated that because the molecular chain of aramid pulp contains rigid benzene rings and flexible ether bonds, forming a unique toughness-rigidity balance structure, which can absorb impact energy through molecular chain slip, while glass fiber lacks the extension of molecular chain, resulting in the decrease of puncture resistance of the flexible intermediate bulk container; at the same time, the surface of aramid pulp contains polar groups, which are easy to form a composite structure with titanium dioxide, enhancing the interfacial bonding; while the surface of glass fiber is a siloxane structure, with weak binding force with titanium dioxide, resulting in the decrease of barrier property.

[0022] When the double-hydroxyl compound is replaced with montmorillonite, the puncture resistance and barrier property of the flexible intermediate bulk container also decrease. It is speculated that because the double-hydroxyl compound has a better binding effect with titanium dioxide-modified aramid pulp and chitosan, thus enhancing the overall effect of the flexible intermediate bulk container.

[0023] Preferably, the mass ratio of magnesium nitrate, aluminum nitrate, urea, titanium dioxide-modified aramid pulp and water is 0.5-0.8: 0.2-0.4: 0.3-0.5: 0.2-0.4: 20-30, preferably 0.6: 0.3: 0.4: 0.3: 25.

[0024] Preferably, the mass ratio of chitosan and titanium dioxide-modified aramid pulp coated with double-hydroxyl compound is 1: 4-6, preferably 1: 5.

[0025] Preferably, the chitosan solution is prepared by mixing chitosan and water with a mass ratio of 2-5: 95-98 and adjusting the pH to 4-6 with acetic acid solution with a mass concentration of 2%.

[0026] Further preferably, the preparation method of the titanium dioxide modified aramid pulp coated with chitosan intercalated double-hydroxy compound: Mix magnesium nitrate, aluminum nitrate, urea, titanium dioxide modified aramid pulp and water evenly, heat and react at 120-130 °C for 6-8 h, filter, and dry to obtain the titanium dioxide modified aramid pulp coated with double-hydroxy compound; add it to the chitosan solution, heat and stir at 60-70 °C for 3-6 h, filter, and dry to obtain.

[0027] In some preferred embodiments, the ethylene content of the ethylene-vinyl alcohol copolymer is 40-50 wt%.

[0028] Preferably, the ethylene content of the ethylene-vinyl alcohol copolymer is 48 wt%, grade: EVOH H4815Soarnol.

[0029] In some preferred embodiments, the vinyl acetate content of the ethylene-vinyl acetate copolymer is 10-16 wt%.

[0030] Preferably, the vinyl acetate content of the ethylene-vinyl acetate copolymer is 14 wt%, grade: ExxonMobil TM EVA 02514FL.

[0031] In some preferred embodiments, the preparation method of the erucic acid modified nano-silica is: Mix nano-silica, erucic acid and ethanol evenly, heat and stir, filter, and dry to obtain.

[0032] Although the ethylene-vinyl alcohol copolymer has good barrier properties, its barrier properties are poor under high humidity conditions; to solve the above problems, the inventors unexpectedly found during the experiment that when erucic acid modified nano-silica is added, the improvement of the barrier properties of the flexible intermediate bulk container under high humidity conditions is greater than that of erucic acid modified nano-cellulose. It is speculated that on the one hand, the long-chain alkyl group of erucic acid is grafted onto the silica surface through chemical bonds to form a dense hydrophobic layer, effectively blocking the penetration of water molecules; even if the nanofibers are modified with erucic acid, their natural hydrophilic skeleton still retains some hygroscopicity, which is likely to cause the penetration of water molecules; on the other hand, the spherical dense barrier property of silica can complement the layered barrier property of the double-hydroxy compound in the antibacterial inner layer, so that the flexible intermediate bulk container still has excellent barrier properties under high humidity conditions.

[0033] Preferably, the preparation method of the erucic acid modified nano-silica is: Mix nano-silica, erucic acid and ethanol evenly, heat and stir at 80-90 °C for 30-60 min, filter, and dry to obtain.

[0034] Preferably, the particle size of the nano-silica is 10-30 nm, preferably 20 nm.

[0035] Preferably, the mass ratio of the nano-silica, erucic acid and ethanol is 6 - 10:0.1 - 0.2:25 - 35, preferably 8:0.15:30.

[0036] In some preferred embodiments, the polypropylene includes homopolypropylene and random copolymer polypropylene with a mass ratio of 4 - 6:1.

[0037] Preferably, the melt flow rate of the homopolypropylene is 2 - 4 g / 10 min (230 °C / 2.16 kg).

[0038] Preferably, the melt flow rate of the homopolypropylene is 3.2 g / 10 min (230 °C / 2.16 kg), grade: PPH - F03G.

[0039] Preferably, the melt flow rate of the random copolymer polypropylene is 4 - 8 g / 10 min

[0040] (230 °C / 2.16 kg).

[0041] Preferably, the melt flow rate of the random copolymer polypropylene is 6 g / 10 min

[0042] (230 °C / 2.16 kg), grade: Moplen RP210M.

[0043] In some preferred embodiments, the thickness percentages of the antibacterial inner layer, barrier intermediate layer and waterproof outer layer are 20 - 30%:45 - 65%:15 - 25%, preferably 25%:55%:20%.

[0044] Preferably, the thickness of the multi - layer food - use shipping bag with high - barrier sealing and waterproofing is 80 - 100 μm.

[0045] The second aspect of the present invention provides a preparation method of the above - mentioned multi - layer food - use shipping bag with high - barrier sealing and waterproofing, which includes the following steps: respectively placing the raw materials of the antibacterial inner layer, the raw materials of the barrier intermediate layer and the raw materials of the waterproof outer layer in a three - layer co - extrusion blown film machine, and obtaining the product through melt extrusion and blown film.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] 1. The present invention creatively prepares titanium dioxide - modified aramid pulp coated with chitosan - intercalated dihydroxy compound, which realizes the synergistic improvement of the antibacterial property, puncture resistance and barrier property of the shipping bag compared with the single titanium dioxide - modified aramid pulp and chitosan - intercalated dihydroxy compound.

[0048] 2. The present invention uses aramid pulp to improve the puncture resistance and barrier property of the shipping bag.

[0049] 3. The present invention uses a dihydroxy compound to improve the puncture resistance and barrier property of the flexible intermediate bulk container (FIBC).

[0050] 4. The present invention uses erucic acid-modified nano-silica to improve the barrier property of the FIBC under high humidity conditions. Detailed Embodiments

[0051] For a clearer understanding of the technical features, objectives, and effects of the present invention, the specific implementation embodiments will now be described in detail.

[0052] The present invention will be further described below in conjunction with embodiments, but the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific uses. The implementation conditions not specified are conventional conditions in the industry. The technical features involved in each implementation mode of the present invention can be combined with each other as long as they do not conflict with each other.

[0053] In the following embodiments and comparative examples, unless otherwise specified, the raw materials used are all commercially available or prepared by conventional methods in the art.

[0054] Embodiment 1

[0055] A multi-layer food-use flexible intermediate bulk container with high barrier and sealing waterproof properties, which is composed of an antibacterial inner layer, a barrier intermediate layer, and a waterproof outer layer;

[0056] The antibacterial inner layer is composed of aramid pulp modified with titanium dioxide coated with a polyethylene and chitosan intercalated dihydroxy compound in a mass ratio of 10:1;

[0057] The barrier intermediate layer is composed of an ethylene-vinyl alcohol copolymer, an ethylene-vinyl acetate copolymer, and erucic acid-modified nano-silica in a mass ratio of 86:10:4;

[0058] The waterproof outer layer is polypropylene.

[0059] The polyethylene is composed of low-density polyethylene and linear low-density polyethylene in a mass ratio of 1:3.

[0060] The melt flow rate of the low-density polyethylene is 4 g / 10 min (190 °C / 2.16 kg), grade: Anteo TM FK1820.

[0061] The melt flow rate of the linear low-density polyethylene is 1.5 g / 10 min (190 °C / 2.16 kg), grade: Sinopec Maoming 2426K.

[0062] Preparation method of the titanium dioxide modified aramid pulp: Mix the tetrabutyl titanate and the ethanol dispersion of aramid pulp evenly, carry out a heating reaction at 70 °C for 3 h, and after the reaction is completed, wash and dry to obtain.

[0063] The mass ratio of the tetrabutyl titanate (CAS No.: 5593-70-4) to the aramid pulp is 1:2.5.

[0064] The fiber length of the aramid pulp is 0.65 - 1.05 mm, purchased from Yantai Taihexing Material Technology Co., Ltd., model: 1628.

[0065] The mass concentration of the ethanol dispersion of the aramid pulp is 20%.

[0066] Preparation method of the chitosan intercalated double-hydroxide compound coated titanium dioxide modified aramid pulp: Mix magnesium nitrate, aluminum nitrate, urea, titanium dioxide modified aramid pulp and water evenly, carry out a heating reaction at 120 °C for 7 h, filter, and dry to obtain the double-hydroxide compound coated titanium dioxide modified aramid pulp; add it to the chitosan solution, carry out a heating and stirring at 60 °C for 5 h, filter, and dry to obtain.

[0067] The mass ratio of the magnesium nitrate (CAS No.: 13446-18-9), aluminum nitrate (CAS No.: 7784-27-2), urea (CAS No.: 57-13-6), titanium dioxide modified aramid pulp to water is 0.6:0.3:0.4:0.3:25.

[0068] The mass ratio of the chitosan to the double-hydroxide compound coated titanium dioxide modified aramid pulp is 1:5.

[0069] The chitosan solution is prepared by mixing chitosan (CAS No.: 9012-76-4) and water with a mass ratio of 3:97, and adjusting the pH to 5 with an acetic acid solution with a mass concentration of 2%.

[0070] The ethylene content of the ethylene-vinyl alcohol copolymer is 48 wt%, brand: EVOH H4815 Soarnol.

[0071] The vinyl acetate content of the ethylene-vinyl acetate copolymer is 14 wt%, brand: ExxonMobil TM EVA 02514FL.

[0072] Preparation method of the erucic acid modified nano-silica: Mix nano-silica, erucic acid and ethanol evenly, carry out a heating and stirring at 80 °C for 40 min, filter, and dry to obtain.

[0073] The mass ratio of the nano-silica, erucic acid (CAS No.: 112-86-7) and ethanol is 8:0.15:30.

[0074] The particle size of the nano-silica is 20 nm, purchased from Xi'an Bona Material Technology Co., Ltd., model: BN-SiO 2 -01.

[0075] The polypropylene described above includes homopolypropylene and random copolymer polypropylene with a mass ratio of 5:1.

[0076] The melt flow rate of the homopolypropylene is 3.2 g / 10 min (230 °C / 2.16 kg), grade: PPH-F03G.

[0077] The melt flow rate of the random copolymer polypropylene is 6 g / 10 min (230 °C / 2.16 kg), grade: MoplenRP210M.

[0078] The thickness percentages of the antibacterial inner layer, barrier intermediate layer and waterproof outer layer are 25%:55%:20%.

[0079] The thickness of the multi-layer food packaging bag with high barrier, sealing and waterproofing is 100 μm.

[0080] The preparation method of the above multi-layer food packaging bag with high barrier, sealing and waterproofing is as follows: Place the raw materials of the antibacterial inner layer, the raw materials of the barrier intermediate layer and the raw materials of the waterproof outer layer in a three-layer co-extrusion blown film machine respectively, and obtain the product through melt extrusion and blown film.

[0081] Example 2

[0082] A multi-layer food packaging bag with high barrier, sealing and waterproofing, the difference from Example 1 is only that the antibacterial inner layer is made of aramid pulp modified by titanium dioxide coated with a chitosan intercalated dihydroxy compound and polyethylene with a mass ratio of 15:1; the barrier intermediate layer is made of ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer and erucic acid modified nano-silica with a mass ratio of 93:5:2; the rest are the same.

[0083] The preparation method of the above multi-layer food packaging bag with high barrier, sealing and waterproofing is the same as that of Example 1.

[0084] Example 3

[0085] A multi-layer food packaging bag with high barrier, sealing and waterproofing, the difference from Example 1 is only that the antibacterial inner layer is made of aramid pulp modified by titanium dioxide coated with a chitosan intercalated dihydroxy compound and polyethylene with a mass ratio of 12:1;

[0086] The barrier intermediate layer consists of ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, and erucic acid-modified nano-silica with a mass ratio of 90:7:3; the rest are the same.

[0087] The preparation method of the above multi-layer food packaging bag with high barrier, sealing and waterproof properties is the same as that in Example 1.

[0088] Comparative Example 1

[0089] The difference from Example 3 is that the aramid pulp modified by titanium dioxide coated with chitosan intercalated dihydroxy compound is replaced with aramid pulp modified by titanium dioxide of the same mass; the rest are the same.

[0090] Comparative Example 2

[0091] The difference from Example 3 is that the aramid pulp modified by titanium dioxide coated with chitosan intercalated dihydroxy compound is replaced with chitosan intercalated dihydroxy compound of the same mass; the rest are the same.

[0092] Comparative Example 3

[0093] The difference from Example 3 is that the aramid pulp is replaced with glass fiber of the same mass. The fiber diameter of the glass fiber is 14μm, purchased from Qingdao Jiachuang New Materials Co., Ltd., product number: 415A; the rest are the same.

[0094] Comparative Example 4

[0095] The difference from Example 3 is that the aramid pulp modified by titanium dioxide coated with chitosan intercalated dihydroxy compound is replaced with aramid pulp modified by titanium dioxide coated with chitosan intercalated montmorillonite of the same mass;

[0096] The preparation method of the aramid pulp modified by titanium dioxide coated with chitosan intercalated montmorillonite is as follows: Add montmorillonite and aramid pulp modified by titanium dioxide into the chitosan solution, heat and stir at 60°C for 5h, filter, and dry to obtain; the mass ratio of chitosan, montmorillonite and aramid pulp modified by titanium dioxide is 1:

[0097] 3.5:1.5; the montmorillonite is purchased from Guangzhou Yifeng Chemical Technology Co., Ltd., model: TY-710C; the rest are the same.

[0098] Comparative Example 5

[0099] The difference from Example 3 is that the erucic acid-modified nano-silica is replaced with nano-silica of the same mass, and the rest are the same.

[0100] Comparative Example 6

[0101] The difference from Example 3 is that nano-silica is replaced with nano-cellulose of the same mass. The nano-cellulose is purchased from Zhejiang Jinjiahao Green Nano Materials Co., Ltd., model: CNF-B5; the rest are the same.

[0102] Performance test:

[0103] 1. Oxygen transmission rate: Tested according to standard GB / T 1038-2022;

[0104] 2. Water vapor transmission rate: Tested according to standard GB / T 1037-2021;

[0105] 3. Antibacterial rate: Tested according to standard GB / T 31402-2015;

[0106] 4. Puncture resistance: Tested according to standard GB / T 37841-2019;

[0107] The results are shown in Table 1:

[0108] Table 1 Performance test results of high-barrier, sealed and waterproof multi-layer food shipping bags of Examples 1-3 and Comparative Examples 1-6

[0109]

[0110] As can be seen from Table 1, in Comparative Example 1, the titanium dioxide-modified aramid pulp coated with chitosan intercalated dihydroxy compound was replaced with titanium dioxide-modified aramid pulp of the same mass; in Comparative Example 2, the titanium dioxide-modified aramid pulp coated with chitosan intercalated dihydroxy compound was replaced with chitosan intercalated dihydroxy compound of the same mass; the barrier performance, puncture resistance and antibacterial performance of the obtained shipping bags deteriorated, and from the perspective of puncture resistance, the sum of the puncture resistances of Comparative Example 1 and Comparative Example 2 was still inferior to that of Examples 1-3, indicating that the combination of titanium dioxide-modified aramid pulp and chitosan intercalated dihydroxy compound improved the puncture resistance of the shipping bag through a synergistic effect.

[0111] In Comparative Example 3, the aramid pulp was replaced with glass fiber of the same mass; in Comparative Example 4, the titanium dioxide-modified aramid pulp coated with chitosan intercalated dihydroxy compound was replaced with titanium dioxide-modified aramid pulp coated with chitosan intercalated montmorillonite of the same mass; the barrier performance and puncture resistance of the obtained shipping bags deteriorated.

[0112] In Comparative Example 5, the erucic acid-modified nano-silica was replaced with nano-silica of the same mass; in Comparative Example 6, the nano-silica was replaced with nano-cellulose of the same mass; the barrier performance of the obtained shipping bags, especially the barrier performance under high humidity conditions, decreased significantly.

[0113] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than limiting the protection scope of the present invention. Any simple modification or equivalent replacement made by those of ordinary skill in the art to the technical solution of the present invention shall not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A high barrier, sealed and waterproof multi-layer food container bag, characterized in that: It includes an antimicrobial inner layer, a barrier middle layer, and a waterproof outer layer; The antibacterial inner layer comprises polyethylene and chitosan intercalated dihydroxy compound coated titanium dioxide modified aramid pulp in a mass ratio of 10-15:1; The barrier intermediate layer comprises ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer and erucic acid-modified nano-silica in a mass ratio of 86-93:5-10:2-4; The waterproof outer layer comprises polypropylene.

2. The high barrier, sealed and waterproof multi-layer food container bag according to claim 1, characterized in that: The polyethylene comprises low-density polyethylene and linear low-density polyethylene in a mass ratio of 1:3-5; the melt flow rate of the low-density polyethylene is 3-5g / 10min; and the melt flow rate of the linear low-density polyethylene is 1-2g / 10min.

3. The high barrier, sealed and waterproof multi-layer food container bag according to claim 2, characterized in that: The preparation method of the chitosan intercalated dihydroxy compound-coated titanium dioxide modified aramid pulp comprises the following steps: uniformly mixing magnesium nitrate, aluminum nitrate, urea, titanium dioxide modified aramid pulp and water, heating for reaction, filtering and drying to obtain the titanium dioxide modified aramid pulp coated with the dihydroxy compound; adding the mixture into a chitosan solution, heating and stirring, filtering and drying to obtain the obtained pulp.

4. The high barrier, sealed and waterproof multi-layer food container bag according to claim 3, characterized in that: The mass ratio of the magnesium nitrate, aluminum nitrate, urea, titanium dioxide modified aramid pulp and water is 0.5-0.8: 0.2-0.4: 0.3-0.5: 0.2-0.4: 20-30.

5. The high barrier, sealed and waterproof multi-layer food container bag according to any one of claims 1 to 4, characterized in that: The ethylene content of the ethylene-vinyl alcohol copolymer is 40-50 wt %; the vinyl acetate content of the ethylene-vinyl acetate copolymer is 10-16 wt %.

6. The high barrier, sealed and waterproof multi-layer food container bag according to claim 5, characterized in that: The preparation method of the erucic acid-modified nano-silicon dioxide is as follows: nano-silicon dioxide, erucic acid and ethanol are uniformly mixed, heated and stirred, filtered and dried to obtain the nano-silicon dioxide.

7. The high barrier, sealed and waterproof multi-layer food container bag according to claim 6, characterized in that: The mass ratio of the nano silicon dioxide, erucic acid and ethanol is 6-10:0.1-0.2:25-35.

8. The high barrier, sealed and waterproof multi-layer food container bag according to claim 7, characterized in that: The polypropylene comprises homopolypropylene and random copolymer polypropylene in a mass ratio of 10-15:1; the melt flow rate of the homopolypropylene is 2-4 g / 10 min; and the melt flow rate of the random copolymer polypropylene is 4-8 g / 10 min.

9. The high barrier, sealed and waterproof multi-layer food container bag according to any one of claims 6 to 8, characterized in that: The thickness percentages of the antibacterial inner layer, the barrier middle layer and the waterproof outer layer are 20-30%: 45-65%: 15-25%.

10. The method for preparing the high barrier, sealed and waterproof multi-layer food container bag according to any one of claims 1 to 9, characterized in that: The following steps are involved: The raw materials of the antibacterial inner layer, the raw materials of the barrier middle layer and the raw materials of the waterproof outer layer are respectively placed in a three-layer co-extrusion film blowing machine, and the film is blown by melt extrusion to obtain the product.

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