A water-resistant packaging box and its preparation process

Abstract

The present invention relates to the technical field of packaging boxes, and in particular to a water-resistant packaging box and a preparation process thereof. The present invention prepares a water-resistant packaging box by coating a layer of waterproof coating on the packaging box. Acetylated potato starch is added to the packaging box. The potato starch is acetylated, vinyl is introduced into the packaging box, and acetyl groups are also present in the coating. At this time, the waterproof coating is not easy to peel off or fall off, thereby improving the service life of the packaging box. The present invention uses hexadecyltrimethoxysilane and tetraethyl silicate to modify nano ferrosoferric oxide, so that the surface of the nano ferrosoferric oxide has a nano-protruding hydrophobic shell-core structure, thereby further enhancing the water resistance of the packaging box.

Description

Technical Field

[0001] The invention relates to the technical field of packaging boxes, in particular to a water-resistant packaging box and a preparation process thereof. Background Art

[0002] Packaging boxes can be used to package products and protect them from contact with the outside world. With the continuous development of the packaging industry, the performance requirements for packaging materials are getting higher and higher, especially for the water resistance of packaging boxes. Water-resistant packaging boxes can effectively prevent products from getting damp and deteriorating in a humid environment, and extend the service life of products, so they have important application value. However, traditional packaging boxes have poor water resistance, and the bonding strength between the coating and the packaging box is poor, so the packaging box has a short life.

[0003] In order to solve the above problems and improve the water resistance of a packaging box, the present invention provides a water-resistant packaging box and a preparation process thereof. Summary of the invention

[0004] The object of the present invention is to provide a water-resistant packaging box and a preparation process thereof to solve the problems raised in the above background technology.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A preparation process of a water-resistant packaging box comprises the following steps:

[0007] Step 1: Take polypropylene, acetylated potato starch and pentaerythritol stearate, mix them at a speed of 400-500 rpm for 5-10 minutes, add an antioxidant, continue mixing and stirring for 10-15 minutes to obtain a mixture; extrude the mixture into granules and shape it to obtain a packaging box;

[0008] Step 2: Take nanocellulose-ferroferric oxide composite, bisphenol A epoxy resin, silicone acrylic emulsion, defoamer, and m-phenylenediamine curing agent, stir evenly to obtain a waterproof coating;

[0009] Step 3: Apply the waterproof coating on the packaging box, let it stand for 5-10 minutes, introduce a magnetic field, set the magnetic field direction horizontally with the packaging box substrate, and the magnetic field strength is 220-240mT, and then cure to obtain a water-resistant packaging box.

[0010] More optimally, the preparation method of the acetylated potato starch is: take potato starch and deionized water, stir evenly, add sodium hydroxide solution, adjust the pH value to 8.0-8.4, add acetic anhydride dropwise, and at the same time, maintain the pH value of the sodium hydroxide solution at 8.0-8.4, react for 50-70 minutes, then add dilute hydrochloric acid dropwise, filter, wash, dry, and crush to obtain acetylated potato starch.

[0011] More optimally, the packaging box comprises the following ingredients, by weight: 50-70 parts by weight of polypropylene, 25-32 parts by weight of acetylated potato starch, 7-10 parts by weight of pentaerythritol stearate, and 3-6 parts by weight of antioxidant.

[0012] More optimally, the antioxidant is any one or more of antioxidant 168 and antioxidant 1010.

[0013] More optimally, the waterproof coating comprises the following ingredients, by weight: 6-8 parts of nanocellulose-ferroferric oxide composite, 25-30 parts of bisphenol A epoxy resin, 10-13 parts of silicone acrylic emulsion, 4-5 parts of defoamer, and 15-17 parts of m-phenylenediamine curing agent.

[0014] More optimally, the preparation method of the nanocellulose-ferroferric oxide complex is: take modified nanocellulose and N,N-dimethylformamide, stir evenly, add modified nanoferroferric oxide suspension, stir at 85-90°C for 14-16h, filter, wash and dry to obtain the nanocellulose-ferroferric oxide complex.

[0015] Preferably, the preparation method of the modified nanocellulose comprises the following steps:

[0016] S1: Take wood pulp fiber and deionized water, crush and filter, add acetone, soak for 4-5 hours, filter, add glacial acetic acid, soak for 4-5 hours, filter, and obtain pretreated cellulose;

[0017] S2: Take acetic acid, toluene and sulfuric acid, mix them evenly, add pretreated cellulose and acetic anhydride, heat to 55-60°C, stir for 5-7h, add deionized water, continue stirring, centrifuge, filter, wash and dry to obtain modified nanocellulose.

[0018] More optimally, the preparation method of the modified nano-ferroferric oxide suspension is: take ferric chloride and ferrous chloride, add them to an ammonia solution, introduce argon, stir for 40-50 minutes at 70-72°C, filter and wash, add hexadecyltrimethoxysilane, tetraethyl silicate, ethanol, and ammonia water, stir for 6-8 hours, and obtain a modified nano-ferroferric oxide suspension.

[0019] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0020] (1) The present invention coats a layer of waterproof coating on a packaging box to prepare a water-resistant packaging box. Acetylated potato starch is added to the packaging box. The potato starch is acetylated, vinyl is introduced into the packaging box, and acetyl groups are also present in the coating. At this time, the coating fits the packaging box more closely, the coating is more durable, and is not easy to peel or fall off, thereby improving the service life of the packaging box.

[0021] (2) The present invention performs acetylation modification on nanocellulose, replacing the hydroxyl groups on the surface of the nanocellulose with acetyl groups, thereby reducing the surface polarity of the modified nanocellulose and improving the hydrophobicity of the modified nanocellulose.

[0022] The present invention uses hexadecyl trimethoxysilane and tetraethyl silicate to modify nano ferroferric oxide, so that the surface of the nano ferroferric oxide has a hydrophobic shell-core structure with nano protrusions, thereby further enhancing the water resistance of the packaging box. The modified nano cellulose is compounded with the modified nano ferroferric oxide, thereby improving the dispersibility of the nano cellulose-ferroferric oxide composite, thereby improving the hydrophobicity of the modified nano cellulose.

[0023] Since ferroferric oxide is magnetic, the present invention introduces a magnetic field, so that the nanocellulose-ferroferric oxide complex in the coating is dispersed more evenly, further enhancing the hydrophobicity of the modified nanocellulose. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0025] There is no special restriction on the purchase manufacturers of all raw materials involved in the present invention, and illustratively include: potato starch: can be purchased from Hangzhou Prostar Starch Co., Ltd., with a straight starch content of 26.2%; wood pulp fiber: can be purchased from Dalian Yangrun Trading Co., Ltd., item number: Y0006; polypropylene: can be purchased from Shanghai Yuanye Biotechnology Co., Ltd., item number: S51655; bisphenol A type epoxy resin: model: E44; silicone acrylic emulsion: can be purchased from Jinan Shanhai Chemical Technology Co., Ltd., model: GBRY01; defoaming agent: BYK-094.

[0026] Embodiment 1: A process for preparing a water-resistant packaging box, comprising the following steps:

[0027] Step 1: Preparation of acetylated potato starch:

[0028] Take 30g potato starch and 100mL deionized water, stir evenly, add 1mol / L sodium hydroxide solution, adjust the pH value to 8.2, add 3mL acetic anhydride dropwise, and at the same time add 1mol / L sodium hydroxide solution dropwise to maintain the pH value at 8.2, react for 60min, then add dilute hydrochloric acid dropwise to adjust the pH value of the reaction system to 6.5, filter, wash, dry, and crush to obtain acetylated potato starch;

[0029] Step 2: Preparation of nanocellulose-ferroferric oxide composite:

[0030] S1: Preparation of modified nanocellulose:

[0031] Take 10g of wood pulp fiber and 1000mL of deionized water, crush and filter, add 1000mL of acetone, soak for 4.5h, filter, add 1000mL of glacial acetic acid, soak for 4.5h, filter to obtain pretreated cellulose;

[0032] Take 80 mL of acetic acid, 100 mL of toluene, and 0.4 mL of sulfuric acid, mix them evenly, add the pretreated cellulose and 15 mL of acetic anhydride, heat to 57 ° C, stir for 6 h, add 500 mL of deionized water, continue stirring, centrifuge, filter, wash, and dry to obtain modified nanocellulose;

[0033] S2: Preparation of modified nano-iron tetroxide suspension:

[0034] Take 2 mL of ferric chloride and 2 mL of ferrous chloride, add them to 20 mL of 0.38 mol / L ammonia solution, introduce argon, stir at 71 ° C for 45 min, filter and wash, add 0.2 g of hexadecyltrimethoxysilane, 0.1 g of tetraethyl silicate, 20 mL of ethanol, and 2 mL of ammonia water, stir for 7 h, and obtain a modified nano-iron tetroxide suspension;

[0035] S3: Preparation of nanocellulose-ferroferric oxide composite:

[0036] Take 2 g of modified nanocellulose and 50 mL of N,N-dimethylformamide, stir evenly, add 0.2 g of modified nano-ferroferric oxide suspension, stir at 88 ° C for 15 h, filter, wash and dry to obtain a nanocellulose-ferroferric oxide composite;

[0037] Step 3: Preparation of packaging box:

[0038] Polypropylene, acetylated potato starch and pentaerythritol stearate were mixed at a rotation speed of 450 rpm for 7 minutes, antioxidant 1010 was added, and the mixture was mixed and stirred for 12 minutes to obtain a mixture; the mixture was extruded into granules and formed to obtain a packaging box;

[0039] The packaging box includes the following ingredients, by weight: 60 parts by weight of polypropylene, 30 parts by weight of acetylated potato starch, 8 parts by weight of pentaerythritol stearate, and 5 parts by weight of antioxidant 1010;

[0040] Step 4: Preparation of waterproof coating:

[0041] Take nanocellulose-ferroferric oxide composite, bisphenol A epoxy resin, silicone acrylic emulsion, defoamer, and m-phenylenediamine curing agent, stir evenly to obtain a waterproof coating;

[0042] The waterproof coating comprises the following components, by weight: 7 parts of nanocellulose-ferroferric oxide composite, 27 parts of bisphenol A epoxy resin, 11 parts of silicone acrylic emulsion, 4.5 parts of defoamer, and 16 parts of m-phenylenediamine curing agent;

[0043] Step 5: Preparation of water-resistant packaging box:

[0044] Apply waterproof coating on the packaging box with a coating density of 1.5 mg / cm 2 , let it stand for 7 minutes, introduce a magnetic field, the direction of the magnetic field and the packaging box base are set horizontally, the magnetic field strength is 230mT, and then cure to obtain a water-resistant packaging box.

[0045] Embodiment 2: A process for preparing a water-resistant packaging box, comprising the following steps:

[0046] Step 1: Preparation of acetylated potato starch:

[0047] Take 30g potato starch and 100mL deionized water, stir evenly, add 1mol / L sodium hydroxide solution, adjust the pH value to 8.0, add 3mL acetic anhydride dropwise, and at the same time add 1mol / L sodium hydroxide solution dropwise to maintain the pH value at 8.0, react for 50min, then add dilute hydrochloric acid dropwise to adjust the pH value of the reaction system to 6.5, filter, wash, dry, and crush to obtain acetylated potato starch;

[0048] Step 2: Preparation of nanocellulose-ferroferric oxide composite:

[0049] S1: Preparation of modified nanocellulose:

[0050] Take 10g of wood pulp fiber and 1000mL of deionized water, crush and filter, add 1000mL of acetone, soak for 4h, filter, add 1000mL of glacial acetic acid, soak for 4h, filter to obtain pretreated cellulose;

[0051] Take 80 mL of acetic acid, 100 mL of toluene, and 0.4 mL of sulfuric acid, mix them evenly, add the pretreated cellulose and 15 mL of acetic anhydride, heat to 55 °C, stir for 5 h, add 500 mL of deionized water, continue stirring, centrifuge, filter, wash, and dry to obtain modified nanocellulose;

[0052] S2: Preparation of modified nano-iron tetroxide suspension:

[0053] Take 2 mL of ferric chloride and 2 mL of ferrous chloride, add them to 20 mL of 0.38 mol / L ammonia solution, introduce argon, stir at 70 ° C for 40 min, filter and wash, add 0.2 g of hexadecyltrimethoxysilane, 0.1 g of tetraethyl silicate, 20 mL of ethanol, and 2 mL of ammonia water, stir for 6 h to obtain a modified nano-iron tetroxide suspension;

[0054] S3: Preparation of nanocellulose-ferroferric oxide composite:

[0055] Take 2 g of modified nanocellulose and 50 mL of N,N-dimethylformamide, stir evenly, add 0.2 g of modified nano-ferroferric oxide suspension, stir at 85 ° C for 14 h, filter, wash and dry to obtain a nanocellulose-ferroferric oxide complex;

[0056] Step 3: Preparation of packaging box:

[0057] Polypropylene, acetylated potato starch and pentaerythritol stearate were mixed at a rotation speed of 400 rpm for 5 minutes, antioxidant 1010 was added, and the mixture was mixed and stirred for 10 minutes to obtain a mixture; the mixture was extruded into granules and formed to obtain a packaging box;

[0058] The packaging box includes the following ingredients, by weight: 50 parts by weight of polypropylene, 25 parts by weight of acetylated potato starch, 7 parts by weight of pentaerythritol stearate, and 3 parts by weight of antioxidant 1010;

[0059] Step 4: Preparation of waterproof coating:

[0060] Take nanocellulose-ferroferric oxide composite, bisphenol A epoxy resin, silicone acrylic emulsion, defoamer, and m-phenylenediamine curing agent, stir evenly to obtain a waterproof coating;

[0061] The waterproof coating comprises the following ingredients, by weight: 6 parts of nanocellulose-ferroferric oxide composite, 25 parts of bisphenol A epoxy resin, 10 parts of silicone acrylic emulsion, 4 parts of defoamer, and 15 parts of m-phenylenediamine curing agent;

[0062] Step 5: Preparation of water-resistant packaging box:

[0063] Apply waterproof coating on the packaging box with a coating density of 1.5 mg / cm 2 , let it stand for 5 minutes, introduce a magnetic field, set the direction of the magnetic field horizontally with the packaging box substrate, the magnetic field intensity is 220mT, and then cure to obtain a water-resistant packaging box.

[0064] Embodiment 3: A process for preparing a water-resistant packaging box, comprising the following steps:

[0065] Step 1: Preparation of acetylated potato starch:

[0066] Take 30g potato starch and 100mL deionized water, stir evenly, add 1mol / L sodium hydroxide solution, adjust the pH value to 8.4, add 3mL acetic anhydride dropwise, and at the same time add 1mol / L sodium hydroxide solution dropwise to maintain the pH value at 8.4, react for 70min, then add dilute hydrochloric acid dropwise to adjust the pH value of the reaction system to 6.5, filter, wash, dry, and crush to obtain acetylated potato starch;

[0067] Step 2: Preparation of nanocellulose-ferroferric oxide composite:

[0068] S1: Preparation of modified nanocellulose:

[0069] Take 10g of wood pulp fiber and 1000mL of deionized water, crush and filter, add 1000mL of acetone, soak for 5h, filter, add 1000mL of glacial acetic acid, soak for 5h, filter to obtain pretreated cellulose;

[0070] Take 80 mL of acetic acid, 100 mL of toluene, and 0.4 mL of sulfuric acid, mix them evenly, add the pretreated cellulose and 15 mL of acetic anhydride, heat to 60 ° C, stir for 7 h, add 500 mL of deionized water, continue stirring, centrifuge, filter, wash, and dry to obtain modified nanocellulose;

[0071] S2: Preparation of modified nano-iron tetroxide suspension:

[0072] Take 2 mL of ferric chloride and 2 mL of ferrous chloride, add them to 20 mL of 0.38 mol / L ammonia solution, pass argon, stir at 72 ° C for 50 min, filter and wash, add 0.2 g of hexadecyltrimethoxysilane, 0.1 g of tetraethyl silicate, 20 mL of ethanol, and 2 mL of ammonia water, stir for 8 h, and obtain a modified nano-iron tetroxide suspension;

[0073] S3: Preparation of nanocellulose-ferroferric oxide composite:

[0074] Take 2 g of modified nanocellulose and 50 mL of N,N-dimethylformamide, stir evenly, add 0.2 g of modified nano-ferroferric oxide suspension, stir at 90 ° C for 16 h, filter, wash and dry to obtain a nanocellulose-ferroferric oxide composite;

[0075] Step 3: Preparation of packaging box:

[0076] Polypropylene, acetylated potato starch and pentaerythritol stearate were mixed at a rotation speed of 500 rpm for 10 minutes, antioxidant 1010 was added, and the mixture was mixed and stirred for 15 minutes to obtain a mixture; the mixture was extruded into granules and formed to obtain a packaging box;

[0077] The packaging box includes the following ingredients, by weight: 70 parts by weight of polypropylene, 32 parts by weight of acetylated potato starch, 10 parts by weight of pentaerythritol stearate, and 6 parts by weight of antioxidant 1010;

[0078] Step 4: Preparation of waterproof coating:

[0079] Take nanocellulose-ferroferric oxide composite, bisphenol A epoxy resin, silicone acrylic emulsion, defoamer, and m-phenylenediamine curing agent, stir evenly to obtain a waterproof coating;

[0080] The waterproof coating comprises the following components, by weight: 8 parts of nanocellulose-ferroferric oxide composite, 30 parts of bisphenol A epoxy resin, 13 parts of silicone acrylic emulsion, 5 parts of defoamer, and 17 parts of m-phenylenediamine curing agent;

[0081] Step 5: Preparation of water-resistant packaging box:

[0082] Apply waterproof coating on the packaging box with a coating density of 1.5 mg / cm 2 , let it stand for 10 minutes, introduce a magnetic field, the direction of the magnetic field and the packaging box base are set horizontally, the magnetic field intensity is 240mT, and then cure to obtain a water-resistant packaging box.

[0083] Comparative Example 1: The potato starch was not acetylated, and the rest was the same as in Example 1:

[0084] Step 1: Preparation of nanocellulose-ferroferric oxide composite:

[0085] S1: Preparation of modified nanocellulose:

[0086] Take 10g of wood pulp fiber and 1000mL of deionized water, crush and filter, add 1000mL of acetone, soak for 4.5h, filter, add 1000mL of glacial acetic acid, soak for 4.5h, filter to obtain pretreated cellulose;

[0087] Take 80 mL of acetic acid, 100 mL of toluene, and 0.4 mL of sulfuric acid, mix them evenly, add the pretreated cellulose and 15 mL of acetic anhydride, heat to 57 ° C, stir for 6 h, add 500 mL of deionized water, continue stirring, centrifuge, filter, wash, and dry to obtain modified nanocellulose;

[0088] S2: Preparation of modified nano-iron tetroxide suspension:

[0089] Take 2 mL of ferric chloride and 2 mL of ferrous chloride, add them to 20 mL of 0.38 mol / L ammonia solution, introduce argon, stir at 71 ° C for 45 min, filter and wash, add 0.2 g of hexadecyltrimethoxysilane, 0.1 g of tetraethyl silicate, 20 mL of ethanol, and 2 mL of ammonia water, stir for 7 h, and obtain a modified nano-iron tetroxide suspension;

[0090] S3: Preparation of nanocellulose-ferroferric oxide composite:

[0091] Take 2 g of modified nanocellulose and 50 mL of N,N-dimethylformamide, stir evenly, add 0.2 g of modified nano-ferroferric oxide suspension, stir at 88 ° C for 15 h, filter, wash and dry to obtain a nanocellulose-ferroferric oxide composite;

[0092] Step 2: Preparation of packaging box:

[0093] Polypropylene, potato starch and pentaerythritol stearate were mixed at a rotation speed of 450 rpm for 7 minutes, antioxidant 1010 was added, and the mixture was mixed and stirred for 12 minutes to obtain a mixture; the mixture was extruded into granules and formed to obtain a packaging box;

[0094] The packaging box includes the following ingredients, by weight: 60 parts by weight of polypropylene, 30 parts by weight of potato starch, 8 parts by weight of pentaerythritol stearate, and 5 parts by weight of antioxidant 1010;

[0095] Step 3: Preparation of waterproof coating:

[0096] Take nanocellulose-ferroferric oxide composite, bisphenol A epoxy resin, silicone acrylic emulsion, defoamer, and m-phenylenediamine curing agent, stir evenly to obtain a waterproof coating;

[0097] The waterproof coating comprises the following components, by weight: 7 parts of nanocellulose-ferroferric oxide composite, 27 parts of bisphenol A epoxy resin, 11 parts of silicone acrylic emulsion, 4.5 parts of defoamer, and 16 parts of m-phenylenediamine curing agent;

[0098] Step 4: Preparation of water-resistant packaging box:

[0099] Apply waterproof coating on the packaging box with a coating density of 1.5 mg / cm 2 , let it stand for 7 minutes, introduce a magnetic field, the direction of the magnetic field and the packaging box base are set horizontally, the magnetic field strength is 230mT, and then cure to obtain a water-resistant packaging box.

[0100] Comparative Example 2: Hexadecyltrimethoxysilane and tetraethyl silicate are not used to modify the nano-iron tetroxide, and the rest is the same as Example 1:

[0101] Step 1: Preparation of acetylated potato starch:

[0102] Take 30g potato starch and 100mL deionized water, stir evenly, add 1mol / L sodium hydroxide solution, adjust the pH value to 8.2, add 3mL acetic anhydride dropwise, and at the same time add 1mol / L sodium hydroxide solution dropwise to maintain the pH value at 8.2, react for 60min, then add dilute hydrochloric acid dropwise to adjust the pH value of the reaction system to 6.5, filter, wash, dry, and crush to obtain acetylated potato starch;

[0103] Step 2: Preparation of nanocellulose-ferroferric oxide composite:

[0104] S1: Preparation of modified nanocellulose:

[0105] Take 10g of wood pulp fiber and 1000mL of deionized water, crush and filter, add 1000mL of acetone, soak for 4.5h, filter, add 1000mL of glacial acetic acid, soak for 4.5h, filter to obtain pretreated cellulose;

[0106] Take 80 mL of acetic acid, 100 mL of toluene, and 0.4 mL of sulfuric acid, mix them evenly, add the pretreated cellulose and 15 mL of acetic anhydride, heat to 57 ° C, stir for 6 h, add 500 mL of deionized water, continue stirring, centrifuge, filter, wash, and dry to obtain modified nanocellulose;

[0107] S2: Preparation of nano-iron tetroxide suspension:

[0108] Take 2 mL of ferric chloride and 2 mL of ferrous chloride, add them to 20 mL of 0.38 mol / L ammonia solution, introduce argon, stir at 71°C, filter and wash to obtain a nano-ferroferric oxide suspension;

[0109] S3: Preparation of nanocellulose-ferroferric oxide composite:

[0110] Take 2 g of modified nanocellulose and 50 mL of N,N-dimethylformamide, stir evenly, add 0.2 g of modified nano-ferroferric oxide suspension, stir at 88 ° C for 15 h, filter, wash and dry to obtain a nanocellulose-ferroferric oxide composite;

[0111] Step 3: Preparation of packaging box:

[0112] Polypropylene, acetylated potato starch and pentaerythritol stearate were mixed at a rotation speed of 450 rpm for 7 minutes, antioxidant 1010 was added, and the mixture was mixed and stirred for 12 minutes to obtain a mixture; the mixture was extruded into granules and formed to obtain a packaging box;

[0113] The packaging box includes the following ingredients, by weight: 60 parts by weight of polypropylene, 30 parts by weight of acetylated potato starch, 8 parts by weight of pentaerythritol stearate, and 5 parts by weight of antioxidant 1010;

[0114] Step 4: Preparation of waterproof coating:

[0115] Take nanocellulose-ferroferric oxide composite, bisphenol A epoxy resin, silicone acrylic emulsion, defoamer, and m-phenylenediamine curing agent, stir evenly to obtain a waterproof coating;

[0116] The waterproof coating comprises the following components, by weight: 7 parts of nanocellulose-ferroferric oxide composite, 27 parts of bisphenol A epoxy resin, 11 parts of silicone acrylic emulsion, 4.5 parts of defoamer, and 16 parts of m-phenylenediamine curing agent;

[0117] Step 5: Preparation of water-resistant packaging box:

[0118] Apply waterproof coating on the packaging box with a coating density of 1.5 mg / cm 2 , let it stand for 7 minutes, introduce a magnetic field, the direction of the magnetic field and the packaging box base are set horizontally, the magnetic field strength is 230mT, and then cure to obtain a water-resistant packaging box.

[0119] Comparative Example 3: No magnetic field is introduced, the magnetic field direction and the packaging box base are set horizontally, and the rest is the same as Example 1:

[0120] Step 1: Preparation of acetylated potato starch:

[0121] Take 30g potato starch and 100mL deionized water, stir evenly, add 1mol / L sodium hydroxide solution, adjust the pH value to 8.2, add 3mL acetic anhydride dropwise, and at the same time add 1mol / L sodium hydroxide solution dropwise to maintain the pH value at 8.2, react for 60min, then add dilute hydrochloric acid dropwise to adjust the pH value of the reaction system to 6.5, filter, wash, dry, and crush to obtain acetylated potato starch;

[0122] Step 2: Preparation of nanocellulose-ferroferric oxide composite:

[0123] S1: Preparation of modified nanocellulose:

[0124] Take 10g of wood pulp fiber and 1000mL of deionized water, crush and filter, add 1000mL of acetone, soak for 4.5h, filter, add 1000mL of glacial acetic acid, soak for 4.5h, filter to obtain pretreated cellulose;

[0125] Take 80 mL of acetic acid, 100 mL of toluene, and 0.4 mL of sulfuric acid, mix them evenly, add the pretreated cellulose and 15 mL of acetic anhydride, heat to 57 ° C, stir for 6 h, add 500 mL of deionized water, continue stirring, centrifuge, filter, wash, and dry to obtain modified nanocellulose;

[0126] S2: Preparation of modified nano-iron tetroxide suspension:

[0127] Take 2 mL of ferric chloride and 2 mL of ferrous chloride, add them to 20 mL of 0.38 mol / L ammonia solution, introduce argon, stir at 71 ° C for 45 min, filter and wash, add 0.2 g of hexadecyltrimethoxysilane, 0.1 g of tetraethyl silicate, 20 mL of ethanol, and 2 mL of ammonia water, stir for 7 h, and obtain a modified nano-iron tetroxide suspension;

[0128] S3: Preparation of nanocellulose-ferroferric oxide composite:

[0129] Take 2 g of modified nanocellulose and 50 mL of N,N-dimethylformamide, stir evenly, add 0.2 g of modified nano-ferroferric oxide suspension, stir at 88 ° C for 15 h, filter, wash and dry to obtain a nanocellulose-ferroferric oxide composite;

[0130] Step 3: Preparation of packaging box:

[0131] Polypropylene, acetylated potato starch and pentaerythritol stearate were mixed at a rotation speed of 450 rpm for 7 minutes, antioxidant 1010 was added, and the mixture was mixed and stirred for 12 minutes to obtain a mixture; the mixture was extruded into granules and formed to obtain a packaging box;

[0132] The packaging box includes the following ingredients, by weight: 60 parts by weight of polypropylene, 30 parts by weight of acetylated potato starch, 8 parts by weight of pentaerythritol stearate, and 5 parts by weight of antioxidant 1010;

[0133] Step 4: Preparation of waterproof coating:

[0134] Take nanocellulose-ferroferric oxide composite, bisphenol A epoxy resin, silicone acrylic emulsion, defoamer, and m-phenylenediamine curing agent, stir evenly to obtain a waterproof coating;

[0135] The waterproof coating comprises the following components, by weight: 7 parts of nanocellulose-ferroferric oxide composite, 27 parts of bisphenol A epoxy resin, 11 parts of silicone acrylic emulsion, 4.5 parts of defoamer, and 16 parts of m-phenylenediamine curing agent;

[0136] Step 5: Preparation of water-resistant packaging box:

[0137] Apply waterproof coating on the packaging box with a coating density of 1.5 mg / cm 2 , cured to obtain a water-resistant packaging box.

[0138] experiment:

[0139] The water-resistant packaging boxes prepared in Examples 1-3 and Comparative Examples 1-3 were used for performance testing. The water contact angle of the packaging boxes was tested to characterize their water resistance. The adhesion of the waterproof coating of the packaging boxes was tested with reference to GB / T 9286-2021. The packaging boxes were placed at a temperature of 25° C. and a humidity of 60% for 24 hours to test the water absorption rate of the packaging boxes. The obtained data are shown in the following table:

[0140] Water contact angle° Waterproof coating adhesion Water absorption / % Example 1 126 0 0.38 Example 2 124 0 0.40 Example 3 127 0 0.37 Comparative Example 1 122 1 0.52 Comparative Example 2 117 0 0.83 Comparative Example 3 119 0 0.76

[0141] Conclusion: Comparative Example 1 does not acetylate potato starch, the bonding force between the waterproof coating and the packaging box deteriorates, and the adhesion of the waterproof coating deteriorates. Comparative Example 2 does not use hexadecyl trimethoxysilane and tetraethyl silicate to modify nano ferroferric oxide, the water absorption rate of the packaging box increases, and the water resistance decreases. Comparative Example 3 does not introduce a magnetic field, the nanocellulose-ferroferric oxide complex in the coating is unevenly dispersed, and the water resistance of the packaging box decreases. Example 1-3 uses hexadecyl trimethoxysilane and tetraethyl silicate to modify nano ferroferric oxide, so that the surface of nano ferroferric oxide has a hydrophobic shell-core structure with nano protrusions, thereby further enhancing the water resistance of the packaging box. Acetylated potato starch is added to the packaging box. Potato starch is acetylated, vinyl is introduced into the packaging box, and acetyl groups are also present in the coating. At this time, the coating fits the packaging box more closely, the coating adhesion is stronger, and it is not easy to peel off or fall off.

[0142] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A process for preparing a water-resistant packaging box, characterized in that: The following steps are involved: Step 1: Take polypropylene, acetylated potato starch and pentaerythritol stearate, mix them at a speed of 400-500 rpm for 5-10 minutes, add an antioxidant, continue mixing and stirring for 10-15 minutes to obtain a mixture; extrude the mixture into granules and shape it to obtain a packaging box; Step 2: Take nanocellulose-ferroferric oxide composite, bisphenol A epoxy resin, silicone acrylic emulsion, defoamer, and m-phenylenediamine curing agent, stir evenly to obtain a waterproof coating; Step 3: Apply the waterproof coating on the packaging box, let it stand for 5-10 minutes, introduce a magnetic field, set the magnetic field direction horizontally with the packaging box substrate, and the magnetic field strength is 220-240mT, and then cure to obtain a water-resistant packaging box; The preparation method of the nanocellulose-ferroferric oxide composite is as follows: taking modified nanocellulose and N,N-dimethylformamide, stirring evenly, adding modified nanoferroferric oxide suspension, stirring at 85-90° C. for 14-16 hours, filtering, washing, and drying to obtain the nanocellulose-ferroferric oxide composite; The preparation method of the modified nanocellulose comprises the following steps: S1: Take wood pulp fiber and deionized water, crush and filter, add acetone, soak for 4-5 hours, filter, add glacial acetic acid, soak for 4-5 hours, filter, and obtain pretreated cellulose; S2: Take acetic acid, toluene and sulfuric acid, mix them evenly, add pretreated cellulose and acetic anhydride, heat to 55-60°C, stir for 5-7h, add deionized water, continue stirring, centrifuge, filter, wash and dry to obtain modified nanocellulose; The preparation method of the modified nano-ferroferric oxide suspension is as follows: taking ferric chloride and ferrous chloride, adding them into an ammonia solution, introducing argon gas, stirring at 70-72° C. for 40-50 minutes, filtering and washing, adding hexadecyltrimethoxysilane, tetraethyl silicate, ethanol and ammonia water, stirring for 6-8 hours, and obtaining the modified nano-ferroferric oxide suspension.

2. The process for preparing a water-resistant packaging box according to claim 1, characterized in that: The preparation method of the acetylated potato starch comprises the following steps: taking potato starch and deionized water, stirring evenly, adding sodium hydroxide solution, adjusting the pH value to 8.0-8.4, dripping acetic anhydride, and maintaining the pH value of the sodium hydroxide solution at 8.0-8.4, reacting for 50-70 minutes, then dripping dilute hydrochloric acid, filtering, washing, drying, and crushing to obtain the acetylated potato starch.

3. The process for preparing a water-resistant packaging box according to claim 1, characterized in that: The packaging box comprises the following components, by weight: 50-70 parts by weight of polypropylene, 25-32 parts by weight of acetylated potato starch, 7-10 parts by weight of pentaerythritol stearate, and 3-6 parts by weight of antioxidant.

4. The process for preparing a water-resistant packaging box according to claim 3, characterized in that: The antioxidant is any one or more of antioxidant 168 and antioxidant 1010.

5. The process for preparing a water-resistant packaging box according to claim 1, characterized in that: The waterproof coating comprises the following components, measured by weight: 6-8 parts of nanocellulose-ferroferric oxide composite, 25-30 parts of bisphenol A epoxy resin, 10-13 parts of silicone acrylic emulsion, 4-5 parts of defoamer, and 15-17 parts of m-phenylenediamine curing agent.

6. A water-resistant packaging box prepared according to the preparation process of a water-resistant packaging box according to any one of claims 1 to 5.