Environment-friendly corrugated carton and preparation process thereof

Abstract

The invention relates to the field of corrugated carton preparation, in particular to an environment-friendly corrugated carton and a preparation process thereof. An environment-friendly corrugated carton is made of a corrugated board through die cutting, indentation and carton nailing / carton sticking, the corrugated board sequentially comprises a surface paper layer, a first pearl wool layer, corrugated paper, a second pearl wool layer and a bottom paper layer, all the layers are bonded through adhesives, polystyrene foam is filled in a groove of the corrugated paper, and the surface paper layer, the first pearl wool layer, the second pearl wool layer and the bottom paper layer are bonded through adhesives. The corrugated paper and the polystyrene foam are bonded through an adhesive, and the surface of the surface paper layer and the surface of the bottom paper layer are coated with waterproof paint; the adhesive comprises the following raw materials in parts by weight: 9-15 parts of starch; 0.3 to 0.7 part of caustic soda; 2-3 parts of borax; 700 to 820 parts of water; 48 to 53 parts of polyvinyl alcohol; 7 to 11 parts of toluene diisocynate; 0.7 to 1.3 parts of bentonite; 1-2 parts of an emulsifier; and 0.5-1 part of a stabilizer. The waterproof and moistureproof performance, compressive strength and other mechanical properties of the corrugated carton can be improved.

Description

Technical Field

[0001] The present invention relates to the field of corrugated cardboard box preparation, and particularly to an environment-friendly corrugated cardboard box and its preparation process. Background Art

[0002] Corrugated cardboard boxes are the most widely used packaging products, which are rigid paper boxes made by die-cutting, creasing, nailing or gluing corrugated cardboard. Corrugated cardboard boxes can protect goods, facilitate storage and transportation, and also play the role of beautifying and promoting goods.

[0003] When preparing corrugated cardboard boxes, they are made by die-pressing, creasing, and nailing / gluing corrugated cardboard. Corrugated cardboard is a multi-layer adhesive body, which is composed of at least one layer of corrugated paper and one layer of linerboard paper bonded together. Corrugated cardboard is made by beating native straw pulp and waste paper to make a raw cardboard similar to yellow cardboard, then mechanically processed to roll it into a corrugated shape, and then bonded with linerboard paper on its surface with an adhesive.

[0004] The existing corrugated cardboard boxes have the following problems: the existing corrugated cardboard boxes have poor waterproof performance. The main components of corrugated cardboard are cellulose and hemicellulose, and the surface contains hydrophilic groups - hydroxyl groups, resulting in that corrugated cardboard boxes are very easy to lose their original functions due to moisture absorption; the mechanical properties such as compressive strength of the existing corrugated cardboard boxes are poor and they are easy to be damaged. Summary of the Invention

[0005] In order to improve the waterproof and moisture-proof performance and mechanical properties such as compressive strength of corrugated cardboard boxes, the present application provides an environment-friendly corrugated cardboard box and its preparation process.

[0006] The environment-friendly corrugated cardboard box and its preparation process provided by the present application adopt the following technical solutions: In the first aspect, the present application provides an environment-friendly corrugated cardboard box, which is made by die-cutting, creasing, nailing / gluing corrugated cardboard. The corrugated cardboard sequentially includes: a face paper layer, a first EPE layer, corrugated paper, a second EPE layer, and a bottom paper layer. Each layer is bonded by an adhesive. The grooves of the corrugated paper are filled with polystyrene foam, and the corrugated paper and the polystyrene foam are bonded by the adhesive. The surfaces of the face paper layer and the bottom paper layer are coated with a waterproof coating; The adhesive includes the following raw materials in parts by weight: Starch 9 - 15 parts; caustic soda 0.3 - 0.7 parts; Borax 2 - 3 parts; water 700 - 820 parts; Polyvinyl alcohol 48 - 53 parts; toluene diisocyanate 7 - 11 parts; Bentonite 0.7 - 1.3 parts; emulsifier 1 - 2 parts; stabilizer 0.5 - 1 part.

[0007] By adopting the above technical solution, in the corrugated board, the first EPE layer and the second EPE layer are provided to play a buffering role, so that the corrugated carton can keep warm and shock-absorb. The corrugated paper is filled with polystyrene foam, which improves the compressive strength of the corrugated carton and makes its mechanical properties better. The waterproof coating can form a dense film layer on the face paper layer and the bottom paper layer, preventing water from penetrating and wetting the corrugated carton, and enhancing the waterproof and moisture-proof performance of the corrugated carton.

[0008] The adhesive is a composite adhesive of starch and polyvinyl alcohol. Toluene diisocyanate is added to modify polyvinyl alcohol. By using the reaction of isocyanate groups and hydroxyl groups, polyvinyl alcohol and toluene diisocyanate are crosslinked with each other, improving the strength and water resistance of the adhesive film. After adding starch and borax, they can react with the remaining isocyanate groups. Through the crosslinking effect of borax, starch, polyvinyl alcohol, and toluene diisocyanate form a firm crosslinked network, ensuring the bonding strength while improving the water resistance, so that the corrugated carton can have good moisture-proof performance. Bentonite is filled into the crosslinked network, which is beneficial to improving the drying and film-forming speed of the adhesive, and at the same time enhancing the lubricity and thixotropy of the adhesive film, and improving the roll coating property.

[0009] Optionally, the waterproof coating comprises the following raw materials in parts by weight: 16 - 20 parts of polylactic acid; 4 - 6 parts of polydimethylsiloxane; 1 - 3 parts of silane coupling agent KH-550; 5 - 8 parts of nano-silica powder; 140 - 180 parts of dichloromethane; 30 - 60 parts of ethanol.

[0010] By adopting the above technical solution, polylactic acid and nano-silica powder with high hydrophobicity are selected to prepare the waterproof coating. The silane coupling agent is used to promote the dispersion of nano-silica powder in polylactic acid, improving the stability of the coating. The addition of polydimethylsiloxane is used to enhance the adhesion between the waterproof coating and the corrugated board.

[0011] Optionally, the bentonite is a mixture of calcium-based bentonite and glycerol-modified sodium-based bentonite with a weight ratio of 1:(1.2 - 1.5). The glycerol-modified sodium-based bentonite is made from the following raw materials in parts by weight: 16 - 19 parts of sodium-based bentonite; 2 - 3 parts of glycerol.

[0012] By adopting the above technical solution, sodium-based bentonite is modified with glycerol, making it better blend with polyvinyl alcohol, starch, and water. The compatibility and stability of the glue liquid are better and it will not delaminate.

[0013] Optionally, the emulsifier is selected from one or more of sodium dodecyl sulfonate, sodium stearate, octylphenol polyoxyethylene ether, and nonylphenol polyoxyethylene ether.

[0014] Optionally, the stabilizer is selected from one or more of sodium carboxymethyl cellulose and sodium hydroxyethyl cellulose.

[0015] Optionally, the starch is selected from one or more of corn starch, tapioca starch, and wheat starch.

[0016] Optionally, the nano-silica powder is a modified nano-silica powder, and the modified nano-silica powder is made from the following raw materials in parts by weight: 1-2 parts of trifluoropropyltrimethoxysilane; 12-16 parts of nano-silica powder.

[0017] By adopting the above technical solution, the nano-silica powder is modified by trifluoropropyltrimethoxysilane, reducing the agglomeration of the nano-silica powder, improving the dispersion of the nano-silica powder in the waterproof coating. At the same time, the introduction of fluoride ions further improves the hydrophobic and oil-resistant properties and weather resistance of the nano-silica powder.

[0018] In a second aspect, the present application provides a preparation process for an environmentally friendly corrugated cardboard box, including the following steps: S1. Prepare an adhesive and a waterproof coating, and prepare a face paper layer, a first EPE, a second EPE, a core paper, and a bottom paper layer; S2. Uniformly preheat the core paper using a heating roller, and then heat and roll the core paper using a heated corrugating roller to obtain corrugated paper; S3. Coat the adhesive in the grooves of the corrugated paper, paste the polystyrene foam in the grooves of the corrugated paper, and make the height of the polystyrene foam away from the corrugated paper equal to the height of the groove opening; S4. Spray the adhesive on both sides of the corrugated paper, and paste the first EPE and the second EPE on the opposite sides of the corrugated paper respectively; S5. Spray the adhesive on the sides of the first EPE and the second EPE away from the corrugated paper, and paste the face paper layer and the bottom paper layer on the first EPE and the second EPE respectively, and dry; S6. Coat the waterproof coating on the surfaces of the face paper layer and the bottom paper layer, with a coating amount of 30-50 g / m 2 , first dry at 45-60 °C for 60-70 min, and then cure at 105-120 °C for 30-40 min to obtain a corrugated cardboard; S7. Perform die-cutting, indentation, and box nailing / gluing on the obtained corrugated cardboard to obtain a corrugated cardboard box.

[0019] By adopting the above technical solution, polystyrene foam is filled in the corrugated paper by coating an adhesive, and then other layers are bonded in sequence. Moreover, a waterproof coating is applied to the face paper layer and the bottom paper layer to form a corrugated cardboard with excellent water resistance and compressive strength, and a corrugated cardboard box is prepared.

[0020] Optionally, in step S1, the adhesive is prepared through the following steps: Weigh polyvinyl alcohol and water and add them to a reaction kettle, heat to 80 - 90 °C, stir for 20 - 30 min, cool down to 42 - 45 °C, add an emulsifier and stir, and slowly add toluene diisocyanate at a constant temperature and react for 1 - 1.5 h; Raise the temperature to 60 - 64 °C, add starch, then add caustic soda, and stir and gelatinize for 40 - 50 min; Continue to raise the temperature to 75 - 80 °C, add bentonite, and keep warm and stir for 1.5 - 2 h; Cool to room temperature, add boric acid and a stabilizer, stir evenly, discharge, and obtain the adhesive.

[0021] By adopting the above technical solution, first, toluene diisocyanate is used to modify polyvinyl alcohol, react with gelatinized starch, add bentonite for dispersion and fusion, and finally add boric acid for crosslinking to form a system, thus obtaining the adhesive.

[0022] Optionally, in step S1, the waterproof coating is prepared through the following steps: Add vacuum-dried polylactic acid particles to dichloromethane, stir until the polylactic acid is completely dissolved and uniform to obtain solution a; add nano-silica powder and a silane coupling agent to ethanol, stir magnetically for 50 - 60 min to obtain solution b; mix solution a and solution b, then add polydimethylsiloxane, raise the temperature to 40 - 50 °C and stir for 1 - 1.5 h, and cool to obtain the waterproof coating.

[0023] By adopting the above technical solution, the waterproof coating is obtained through simple stirring and mixing, and the preparation process is simple.

[0024] In summary, the present application has at least one of the following beneficial effects: In the corrugated cardboard, the first EPE layer and the second EPE layer are provided to play a buffering role, so that the corrugated cardboard box can keep warm and shock-absorb. Using polystyrene foam to fill the corrugated paper improves the compressive strength of the corrugated cardboard box and makes its mechanical properties better. The waterproof coating can form a dense film layer on the face paper layer and the bottom paper layer to prevent water from penetrating and wetting the corrugated cardboard box, and improve the waterproof and moisture-proof performance of the corrugated cardboard box.

[0025] The binder selected is a composite binder of starch and polyvinyl alcohol. Toluene diisocyanate is added to modify polyvinyl alcohol. By using the reaction between isocyanate groups and hydroxyl groups, polyvinyl alcohol and toluene diisocyanate are crosslinked with each other, improving the strength and water resistance of the adhesive film. After adding starch and borax, they can react with the remaining isocyanate groups. Through the crosslinking effect of borax, starch, polyvinyl alcohol, and toluene diisocyanate form a firm crosslinked network, ensuring the bonding strength while enhancing the water resistance, so that the corrugated cardboard box can have good moisture-proof performance. Bentonite is filled into the crosslinked network as a filler, which is beneficial to improving the drying and film-forming speed of the binder, while enhancing the lubricity and thixotropy of the adhesive film and improving the roll coating property. Brief Description of the Drawings

[0026] Figure 1 It is a schematic structural diagram of the corrugated cardboard of the present application.

[0027] Description of the Reference Numerals in the Drawings: 1, face paper layer; 2, first EPE layer; 3, corrugated paper; 4, second EPE layer; 5, bottom paper layer; 6, polystyrene foam; 7, waterproof coating. Detailed Embodiments

[0028] Preparation Examples Preparation Example 1 Preparation of Glycerol-Modified Sodium Bentonite Dissolve 1.6 kg of sodium bentonite in 7 kg of water, stir and keep the temperature constant at 85 °C, add 0.2 kg of glycerol, keep stirring and reacting for 2 h, cool to room temperature, centrifuge the product, wash it with clear water, and then place it in an oven. After drying at 35 °C for 1 h, glycerol-modified sodium bentonite is obtained.

[0029] Preparation Example 2 Preparation of Glycerol-Modified Sodium Bentonite Dissolve 1.9 kg of sodium bentonite in 8 kg of water, stir and keep the temperature constant at 90 °C, add 0.3 kg of glycerol, keep stirring and reacting for 2.5 h, cool to room temperature, centrifuge the product, wash it with clear water, and then place it in an oven. After drying at 30 °C for 2 h, glycerol-modified sodium bentonite is obtained.

[0030] Preparation Example 3 Preparation of Modified Nano-Silica Powder Prepare a silane treatment solution by mixing 1 kg of 3-trifluoropropyltrimethoxysilane, 5 kg of deionized water, and 10 kg of ethanol. Mix 12 kg of nano-silica powder with 30 g of absolute ethanol, and ultrasonically disperse to form a mixed solution. Drop the silane treatment solution into the mixed solution and react at a constant temperature of 42 °C for 3 h. The product after the reaction is centrifuged, washed with absolute ethanol, and vacuum dried for 3 h to obtain modified nano-silica powder.

[0031] Preparation Example 4 Preparation of Modified Nano-Silica Powder Prepare a silane treatment solution by mixing 2 kg of trifluoropropyltrimethoxysilane, 8 kg of deionized water, and 16 kg of ethanol. Blend 16 kg of nano-silica powder with 35 g of absolute ethanol, and ultrasonically disperse to form a mixed solution. Drop the silane treatment solution into the mixed solution and react at a constant temperature of 45°C for 3.5 h. The reaction product is centrifuged, washed with absolute ethanol, and vacuum dried for 4 h to obtain the modified nano-silica powder. Example

[0032] Example 1 Preparation of an Environmentally Friendly Corrugated Carton S1. Prepare the adhesive and waterproof coating, and prepare the face paper layer, the first EPE foam, the second EPE foam, the core paper, and the bottom paper layer.

[0033] The adhesive includes the following raw materials: 9 kg of starch, specifically corn starch; 0.3 kg of caustic soda; 2 kg of borax; 700 kg of water; 48 kg of polyvinyl alcohol; 7 kg of toluene diisocyanate; 0.7 kg of bentonite, specifically calcium-based bentonite; 1 kg of emulsifier, specifically sodium dodecyl sulfonate; 0.5 kg of stabilizer, specifically sodium carboxymethyl cellulose.

[0034] The adhesive is prepared through the following steps: Weigh polyvinyl alcohol and water and add them to the reaction kettle. Heat to 80°C, stir for 20 min, cool to 42°C, add the emulsifier and stir, and slowly add toluene diisocyanate at a constant temperature and react for 1 h; Raise the temperature to 60°C, add starch, then add caustic soda, and stir and gelatinize for 40 min; Continue to raise the temperature to 75°C, add bentonite, and keep stirring for 1.5 h; Cool to room temperature, add boric acid and stabilizer, stir evenly, and discharge to obtain the adhesive.

[0035] The waterproof coating includes the following raw materials: 16 kg of polylactic acid with a relative molecular mass of 60,000; 4 kg of polydimethylsiloxane, which already contains a curing agent; 1 kg of silane coupling agent KH-550; 5 kg of nano-silica powder; 140 kg of dichloromethane; 30 kg of ethanol.

[0036] The waterproof coating is prepared through the following steps: Add the vacuum-dried polylactic acid particles to dichloromethane, stir until the polylactic acid is completely dissolved and homogenized to obtain solution a; add nano-silica powder and silane coupling agent to ethanol, stir magnetically for 50 min to obtain solution b; mix solution a and solution b, then add polydimethylsiloxane, heat to 40 °C and stir for 1 h, and cool to obtain a waterproof coating.

[0037] S2. Use a heating roller to preheat the core paper evenly, and then use a heated corrugating roller to heat and roll the core paper to obtain corrugated paper with a corrugated shape; S3. Coat an adhesive in the grooves of the corrugated paper, paste the polystyrene foam in the grooves of the corrugated paper, and make the height of the polystyrene foam away from the corrugated paper equal to the height of the groove opening; S4. Spray an adhesive on both sides of the corrugated paper, and paste the first EPE and the second EPE on the opposite sides of the corrugated paper respectively; S5. Spray an adhesive on the sides of the first EPE and the second EPE away from the corrugated paper, and paste the face paper layer and the bottom paper layer on the first EPE and the second EPE respectively, and dry; S6. Coat the waterproof coating on the surfaces of the face paper layer and the bottom paper layer, and the coating amount is 30 g / m 2 , first dry at 45 °C for 60 min, and cure at 105 °C for 30 min to obtain a corrugated cardboard; S7. Die-cut, indent, and nail / glue the obtained corrugated cardboard to obtain a corrugated carton.

[0038] Example 2 The difference between this example and the example is that the raw materials for preparing the adhesive and the waterproof coating in step S1 and the coating parameters in step S6 are different.

[0039] The adhesive includes the following raw materials: 15 kg of starch, and the starch is specifically tapioca starch; 0.7 kg of caustic soda; 3 kg of borax; 820 kg of water; 53 kg of polyvinyl alcohol; 11 kg of toluene diisocyanate; 1.3 kg of bentonite, and the sodium-based bentonite is specifically selected; 2 kg of emulsifier, and the octylphenol polyoxyethylene ether OP-12 is specifically selected; 1 kg of stabilizer, and the sodium carboxymethyl cellulose is specifically selected.

[0040] The adhesive is prepared through the following steps: Weigh polyvinyl alcohol and water and add them to a reaction kettle, heat to 90 °C, stir for 30 min, cool to 45 °C, add an emulsifier and stir, and slowly add toluene diisocyanate at a constant temperature and react for 1.5 h; Heat to 64 °C and add starch, then add caustic soda, and stir and gelatinize for 50 min; Continue to heat up to 80 °C, add bentonite, and keep stirring for 2 h; Cool to room temperature, add boric acid and stabilizer, stir evenly, and discharge to obtain the adhesive.

[0041] The waterproof coating comprises the following raw materials: 20 kg of polylactic acid with a relative molecular mass of 80,000; 6 kg of polydimethylsiloxane which already contains a curing agent; 3 kg of silane coupling agent KH-550; 8 kg of nano-silica powder; 180 kg of dichloromethane; 60 kg of ethanol.

[0042] The waterproof coating is prepared through the following steps: Add the vacuum-dried polylactic acid particles into dichloromethane, stir until the polylactic acid is completely dissolved and uniform to obtain solution a; add the nano-silica powder and silane coupling agent into ethanol, stir magnetically for 60 min to obtain solution b; mix solution a and solution b, then add polydimethylsiloxane, heat up to 50 °C and stir for 1.5 h, and cool to obtain the waterproof coating.

[0043] In step S6, the coating amount of the waterproof coating is 50 g / m 2 , first dry at 60 °C for 70 min, and then cure at 120 °C for 40 min to obtain the corrugated cardboard.

[0044] Example 3 The difference between this example and the previous example lies in that the adhesive in step S1, the raw materials for preparing the waterproof coating, and the coating parameters in step S6 are different.

[0045] The adhesive comprises the following raw materials: 12 kg of starch, specifically 9 kg of cassava starch and 3 kg of wheat starch are selected for the starch; 0.5 kg of caustic soda; 2.5 kg of borax; 760 kg of water; 51 kg of polyvinyl alcohol; 9 kg of toluene diisocyanate; 1 kg of bentonite, specifically calcium-based bentonite is selected; 1.5 kg of emulsifier, specifically nonylphenol polyoxyethylene ether NP-10 is selected; 0.8 kg of stabilizer, specifically sodium carboxymethyl cellulose is selected.

[0046] The adhesive is prepared through the following steps: Weigh polyvinyl alcohol and water and add them into the reaction kettle, heat up to 85 °C, stir for 25 min, cool down to 43 °C, add the emulsifier and stir, and slowly add toluene diisocyanate at a constant temperature and react for 1 h; Heat up to 62 °C, add starch, then add caustic soda, and stir and gelatinize for 46 min; Continue to heat up to 77 °C, add bentonite, and keep warm and stir for 2 h; Cool to room temperature, add boric acid and stabilizer, stir evenly, discharge, and obtain the adhesive.

[0047] The waterproof coating comprises the following raw materials: 18 kg of polylactic acid with a relative molecular mass of 70,000; 5 kg of polydimethylsiloxane which already contains a curing agent; 2 kg of silane coupling agent KH-550; 7 kg of nano-silica powder; 160 kg of dichloromethane; 45 kg of ethanol.

[0048] The waterproof coating is prepared through the following steps: Add the vacuum-dried polylactic acid particles into dichloromethane, stir until the polylactic acid is completely dissolved and homogenized to obtain solution a; add the nano-silica powder and the silane coupling agent into ethanol, magnetically stir for 55 min to obtain solution b; mix solution a and solution b, then add polydimethylsiloxane, heat up to 45 °C and stir for 1.5 h, and cool to obtain the waterproof coating.

[0049] In step S6, the coating amount of the waterproof coating is 43 g / m 2 , first dry at 50 °C for 63 min, and cure at 115 °C for 35 min to obtain the corrugated cardboard.

[0050] Example 4 The difference between the preparation process of the corrugated box in this example and that in Example 1 is only that: in the raw materials of the adhesive, the bentonite is different.

[0051] For the 0.7 kg of bentonite in this example, 0.3 kg of calcium-based bentonite and 0.4 kg of glycerol-modified sodium-based bentonite prepared in Preparation Example 1 are selected.

[0052] The rest are the same as those in Example 1.

[0053] Example 5 The difference between the preparation process of the corrugated box in this example and that in Example 1 is only that: in the raw materials of the adhesive, the bentonite is different.

[0054] For the 0.7 kg of bentonite in this example, 0.28 kg of calcium-based bentonite and 0.42 kg of glycerol-modified sodium-based bentonite prepared in Preparation Example 1 are selected.

[0055] The rest are the same as those in Example 1.

[0056] Example 6 The difference between the preparation process of the corrugated box in this example and that in Example 1 is only that: in the raw materials of the waterproof coating, the nano-silica powder is different.

[0057] The nano-silica powder of this example is the nano-silica powder prepared in Preparation Example 3.

[0058] The rest are the same as those in Example 1.

[0059] Example 7 The difference in the preparation process of the corrugated cardboard box in this example from that in Example 1 lies only in that the nano-silica powder is different in the raw materials of the waterproof coating.

[0060] The nano-silica powder of this example is the nano-silica powder prepared in Preparation Example 4.

[0061] The rest are the same as those in Example 1.

[0062] Example 8 The difference in the preparation process of the corrugated cardboard box in this example from that in Example 1 lies only in that the bentonite is different in the raw materials of the adhesive, and the nano-silica powder is different in the raw materials of the waterproof coating.

[0063] 0.7 kg of bentonite in this example is 0.3 kg of calcium-based bentonite and 0.4 kg of glycerol-modified sodium-based bentonite prepared in Preparation Example 1; the nano-silica powder of this example is the nano-silica powder prepared in Preparation Example 4.

[0064] The rest are the same as those in Example 1.

[0065] Comparative Example Comparative Example 1 The difference between this comparative example and Example 1 lies only in that polystyrene foam is not filled in the grooves of the corrugated paper in the preparation process of the corrugated cardboard box.

[0066] Comparative Example 2 The difference between this comparative example and Example 1 lies only in that toluene diisocyanate is not added in the raw materials for preparing the adhesive.

[0067] Blank Example A commercially available ordinary corrugated cardboard box is selected as the blank example.

[0068] Performance Test Relevant performance tests are carried out on the corrugated cardboard boxes prepared in Examples 1-8 and Comparative Examples 1-2 and the blank example, and the data are recorded in Table 1.

[0069] Edge crush strength: Measured in accordance with the standard of GB / T 16717-2013 "Packaging Containers Heavy-Duty Corrugated Cardboard Boxes"; Puncture strength: Measured in accordance with the standard of GB / T 6544-2008 "Corrugated Board"; Bursting strength: Measured in accordance with the standard of GB / T 6544-2008 "Corrugated Board"; Waterproof performance: Fold the obtained corrugated cardboard into a groove shape, pour the same amount of clear water into the groove, and observe the water seepage on the surface after standing for 1 h to test the waterproof performance.

[0070] Table 1 According to the data in Table 1, it can be seen that the corrugated cardboard box prepared in this application has excellent mechanical properties and outstanding waterproof performance. In terms of the structure of the corrugated cardboard box in this application, a first EPE layer and a second EPE layer are added, and the corrugated paper is filled with polystyrene foam, so that the corrugated cardboard box can be heat-insulated and shock-absorbed through the structure and can better withstand external pressure.

[0071] In terms of the adhesive of the corrugated cardboard box, this application selects the compound of starch and polyvinyl alcohol, and at the same time adds toluene diisocyanate and borax, so that starch, polyvinyl alcohol, and toluene diisocyanate form a firm cross-linked network, and at the same time adds bentonite as a filler. The adhesive has no formaldehyde release, conforms to the environmental protection concept, has high bonding strength, fast drying speed, and at the same time the adhesive has water resistance.

[0072] A waterproof coating is applied on the face paper layer and the bottom paper layer. The waterproof coating selects the combination of polylactic acid and nano-silica powder, and adds polydimethylsiloxane to improve the adhesion, so as to enhance the waterproof performance of the corrugated cardboard box and does not affect the corrugated cardboard box under humid conditions.

[0073] This specific implementation manner is only an explanation of this application and does not limit this application. After reading this specification, those skilled in the art can make modifications without creative contributions to this specific implementation manner as needed, but as long as it is within the scope of the claims of this application, it is protected by the patent law.

Claims

1. An environmentally friendly corrugated paper box, characterized by: The corrugated paper box is made of corrugated paperboard through die-cutting, creasing, and nailing / gluing. The corrugated paperboard comprises: a surface paper layer (1), a first pearl cotton layer (2), corrugated paper (3), a second pearl cotton layer (4), and a bottom paper layer (5). The layers are bonded by an adhesive. The groove of the corrugated paper (3) is filled with polystyrene foam (6). The corrugated paper (3) and the polystyrene foam (6) are bonded by the adhesive. The surfaces of the surface paper layer (1) and the bottom paper layer (5) are coated with a waterproof coating (7). The adhesive comprises the following raw materials in parts by weight: 9-15 parts of starch; 0.3-0.7 parts of caustic soda; 2-3 parts of borax; 700-820 parts of water; 48-53 parts of polyvinyl alcohol; 7-11 parts of toluene diisocyanate; 0.7-1.3 parts of bentonite; 1-2 parts of emulsifier; 0.5-1 part of stabilizer.

2. The environmentally friendly corrugated paper box according to claim 1, characterized in that: The waterproof coating comprises the following raw materials in parts by weight: Polylactic acid 16-20 parts; 4-6 parts of polydimethylsiloxane; Silane coupling agent KH-550 1-3 parts; 5-8 parts of nano silicon powder; 140-180 parts of dichloromethane; 30-60 parts of ethanol.

3. The environmentally friendly corrugated paper box according to claim 1, characterized in that: The bentonite is a mixture of calcium bentonite and glycerol-modified sodium bentonite in a weight ratio of 1:(1.2-1.5), wherein the glycerol-modified sodium bentonite is made of the following raw materials in parts by weight: 16-19 parts of sodium bentonite; 2-3 parts of glycerol.

4. The environmentally friendly corrugated paper box according to claim 1, characterized in that: The emulsifier is selected from one or more of sodium dodecyl sulfonate, sodium stearate, octylphenol polyoxyethylene ether and nonylphenol polyoxyethylene ether.

5. The environmentally friendly corrugated paper box according to claim 1, characterized in that: The stabilizer is selected from one or more of sodium carboxymethyl cellulose and sodium hydroxyethyl cellulose.

6. The environmentally friendly corrugated paper box according to claim 1, characterized in that: The starch is selected from one or more of corn starch, tapioca starch and wheat starch.

7. The environmentally friendly corrugated paper box according to claim 2, characterized in that: The nano silicon micropowder is modified nano silicon micropowder, and the modified nano silicon micropowder is made of the following raw materials in parts by weight: 1-2 parts of trifluoropropyltrimethoxysilane; 12-16 parts of nano silicon powder.

8. The process for preparing an environmentally friendly corrugated paper box according to any one of claims 1 to 7, characterized in that: The steps include: S1. Prepare adhesive and waterproof coating, prepare face paper, first pearl cotton, second pearl cotton, core paper and bottom paper; S2. Preheat the core paper uniformly using a heating roller, and then heat and roll the core paper with a heated corrugated roller to obtain a corrugated corrugated paper; S3. Apply an adhesive to the groove of the corrugated paper, paste the polystyrene foam in the groove of the corrugated paper, and make the polystyrene foam away from the height of the corrugated paper flush with the height of the groove mouth; S4. Spraying adhesive on both sides of the corrugated paper, and pasting the first pearl cotton and the second pearl cotton on opposite sides of the corrugated paper respectively; S5. Spray adhesive on the first and second EPE foams away from the corrugated paper, and paste the face paper and the backing paper on the first and second EPE foams, respectively, and dry them; S6. Apply waterproof coating to the surface of the face paper and the base paper, with a coating amount of 30-50g / m 2 , first dried at 45-60°C for 60-70min, and cured at 105-120°C for 30-40min to obtain corrugated paperboard; S7. Die-cutting, creasing, nailing / gluing the obtained corrugated paperboard to obtain a corrugated paper box.

9. The process for preparing an environmentally friendly corrugated paper box according to claim 8, characterized in that: In step S1, the adhesive is prepared by the following steps: Weigh polyvinyl alcohol and water and add them to the reactor, heat to 80-90°C, stir for 20-30 minutes, cool to 42-45°C, add emulsifier and stir, slowly add toluene diisocyanate at constant temperature, and react for 1-1.5 hours; Heat to 60-64℃, add starch, then add caustic soda, and stir to gelatinize for 40-50 minutes; Continue to raise the temperature to 75-80℃, add bentonite, and stir for 1.5-2h; The mixture is cooled to room temperature, and boric acid and a stabilizer are added, stirred evenly, and discharged to obtain an adhesive.

10. The process for preparing an environmentally friendly corrugated paper box according to claim 8, characterized in that: In step S1, the waterproof coating is prepared by the following steps: Add vacuum-dried polylactic acid particles into dichloromethane and stir until the polylactic acid is completely dissolved and evenly dissolved to obtain liquid A; add nano-silicon powder and silane coupling agent into ethanol and stir magnetically for 50-60 minutes to obtain liquid B; mix liquid A and liquid B, add polydimethylsiloxane, heat to 40-50°C, stir for 1-1.5 hours, and cool to obtain a waterproof coating.

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