Environment-friendly antibacterial corrugated board and surface treatment process thereof

Abstract

The invention discloses an environment-friendly antibacterial corrugated board and a surface treatment process thereof, the environment-friendly antibacterial corrugated board sequentially comprises an antibacterial composite coating, a pretreated surface paper layer, a first bonding layer, a corrugated core layer, a second bonding layer and a bottom paper layer from outside to inside; the antibacterial composite coating is prepared from the following components in parts by weight: 60-70 parts of bio-based polyurethane emulsion, 5-8 parts of nano zinc oxide, 2-3 parts of sodium alginate, 2-4 parts of polyethylene glycol 400, 0.5-1 part of sodium dodecyl benzene sulfonate and 18-25 parts of deionized water, and the pretreated surface paper layer and the bottom paper layer are raw paper containing a pretreating agent. The pretreatment agent is prepared from the following components in parts by weight: 5-10 parts of wormwood extract, 3-5 parts of chitosan, 1-2 parts of glycerol, 85-92 parts of deionized water and 0.3-0.5 part of citric acid. The invention relates to the technical field of corrugated boards. The paperboard adopts natural environment-friendly raw materials, and is lasting in antibacterial effect, high in physical strength and free of harmful substance residues.

Description

Technical Field

[0001] This invention relates to the field of corrugated cardboard technology, specifically to an environmentally friendly antibacterial corrugated cardboard and its surface treatment process. Background Technology

[0002] Corrugated cardboard, as a widely used packaging material, occupies an important position in the packaging industry due to its advantages such as light weight, low cost, and good cushioning performance. However, as consumers' demands for environmental protection and safety in packaging continue to increase, problems such as insufficient antibacterial properties and poor environmental performance of traditional corrugated cardboard are becoming increasingly prominent.

[0003] In existing technologies, some antibacterial corrugated cardboard uses chemically synthesized antibacterial agents (such as chlorine-containing antibacterial agents, organometallic antibacterial agents, etc.). Although these can achieve a certain antibacterial effect, chemical antibacterial agents are prone to residue, posing environmental risks and potentially impacting human health. Other products achieve antibacterial function only through a single antibacterial layer coating on the surface. This antibacterial effect is not long-lasting, and the coating can easily lead to a decrease in the physical strength and water resistance of the cardboard. Furthermore, the adhesive layer of traditional corrugated cardboard often uses ordinary starch glue, which has insufficient bonding strength and is prone to delamination in humid environments, further affecting the product's lifespan.

[0004] Furthermore, existing antibacterial corrugated cardboard production processes often require the addition of specialized equipment or significant modifications to existing production lines, leading to reduced production efficiency, increased costs, and difficulty in achieving large-scale industrial production. Therefore, developing a type of corrugated cardboard and its surface treatment process that is environmentally friendly, has long-lasting antibacterial effects, excellent physical strength, and is compatible with existing production equipment has become an urgent problem to be solved in the industry. Summary of the Invention

[0005] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides an environmentally friendly antibacterial corrugated cardboard and its surface treatment process. The cardboard uses natural and environmentally friendly raw materials, has a long-lasting antibacterial effect, high physical strength, and no harmful substance residues. At the same time, it provides a surface treatment process that is compatible with existing production equipment, simple and controllable, and has low production costs, enabling large-scale industrial production.

[0006] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: an environmentally friendly antibacterial corrugated cardboard, comprising, from the outside to the inside: Antibacterial composite coating, pre-treated face paper layer, first adhesive layer, corrugated core layer, second adhesive layer and backing paper layer; The antibacterial composite coating is composed of 60-70 parts by weight of bio-based polyurethane emulsion, 5-8 parts by weight of nano zinc oxide, 2-3 parts by weight of sodium alginate, 2-4 parts by weight of polyethylene glycol 400, 0.5-1 parts by weight of sodium dodecylbenzene sulfonate, and 18-25 parts by weight of deionized water. Both the pretreated face paper layer and the back paper layer are base paper containing a pretreatment agent. The pretreatment agent consists of 5-10 parts by weight of Artemisia argyi extract, 3-5 parts by weight of chitosan, 1-2 parts by weight of glycerin, 85-92 parts by weight of deionized water, and 0.3-0.5 parts by weight of citric acid. The base paper is made by mixing softwood pulp and waste paper pulp in a mass ratio of 7:3. The first adhesive layer and the second adhesive layer are composed of 100 parts by weight of cassava starch, 2-3 parts of epichlorohydrin, 3-5 parts of montmorillonite, 2-4 parts of Artemisia argyi extract and 300-350 parts of deionized water.

[0007] Preferably, it further includes an inner layer disposed on one side of the base paper layer, the inner layer being a breathable antibacterial film.

[0008] Preferably, the inner breathable antibacterial membrane is made of sodium alginate and chitosan and has a thickness of 5-8 μm.

[0009] Preferably, the corrugated core layer is made of A-type or C-type corrugated kraft paper, and the basis weight of the corrugated core layer is 100-120 g / m². 2 The basis weight of both the pretreated face paper layer and the base paper layer is 120-150 g / m². 2 .

[0010] Preferably, the thickness of the antibacterial composite coating is 8-12 μm, and the particle size of the nano zinc oxide is 50-100 nm.

[0011] A surface treatment process for preparing the above-mentioned environmentally friendly antibacterial corrugated cardboard includes the following steps: Step 1: Pretreatment of base paper: Weigh out 5-10 parts by weight of Artemisia argyi extract, 3-5 parts by weight of chitosan, 1-2 parts by weight of glycerin, 85-92 parts by weight of deionized water, and 0.3-0.5 parts by weight of citric acid. Mix them evenly to prepare a pretreatment agent. After filtering the pretreatment agent, spray it on both sides of the base paper made of a mixture of softwood pulp and waste paper pulp at a mass ratio of 7:3 using a sprayer. The spraying amount is controlled at 15-20 g / m². 2 The sprayed base paper is then dried to obtain a pretreated face paper layer and a back paper layer. Step 2: Preparation of antibacterial composite coating: Weigh out 60-70 parts by weight of bio-based polyurethane emulsion, 5-8 parts by weight of nano zinc oxide, 2-3 parts by weight of sodium alginate, 2-4 parts by weight of polyethylene glycol 400, 0.5-1 parts by weight of sodium dodecylbenzene sulfonate, and 18-25 parts by weight of deionized water; first mix and stir the deionized water and sodium dodecylbenzene sulfonate, then add the nano zinc oxide and stir, followed by ball milling. Then add the bio-based polyurethane emulsion, sodium alginate, and polyethylene glycol 400 in sequence and stir to adjust the viscosity of the system to obtain the antibacterial composite coating. Step 3: Preparation of adhesive layer: Weigh 100 parts of cassava starch, 2-3 parts of epichlorohydrin, 3-5 parts of montmorillonite, 2-4 parts of Artemisia argyi extract and 300-350 parts of deionized water according to the following weight proportions. Mix them evenly and stir to react, and obtain the raw materials for the first adhesive layer and the second adhesive layer slurry. Step 4: Coating and drying: The antibacterial composite coating obtained in step 2 is coated onto the outer surface of the pretreated paper obtained in step 1 using a roller coater, and then the coated pretreated paper is dried in sections. Step 5: Pressing and forming: The adhesive layer slurry obtained in step 3 is applied to the upper and lower flutes of the corrugated core layer to form the first adhesive layer and the second adhesive layer; then, the pre-treated face paper coated with antibacterial composite coating, the first adhesive layer, the corrugated core layer, the second adhesive layer and the bottom paper layer are stacked in the order of stacking and pressing, and then fed into the press machine to press under the set temperature and pressure to obtain environmentally friendly antibacterial corrugated cardboard.

[0012] Preferably, in step 1, the pretreatment agent is filtered through an 80-mesh filter and the pH value of the pretreatment agent is adjusted to 5.5-6.5 by citric acid. The drying is carried out using a dryer at a temperature of 45-55°C for 5-8 minutes. After drying, the moisture content of the pretreated face paper and back paper is controlled to be 8-10%.

[0013] Preferably, in step 2, the mixing and stirring of deionized water and sodium dodecylbenzenesulfonate is carried out using high-speed stirring at a speed of 800-1000 r / min for 5 minutes; after adding nano-zinc oxide and stirring, ball milling is performed for 15 minutes, and the ball milling time is 20-30 minutes, with the particle size of the nano-zinc oxide controlled at 50-100 nm after ball milling; the addition of bio-based polyurethane emulsion, sodium alginate, and polyethylene glycol 400 is carried out using low-speed stirring at a speed of 300-500 r / min for 20 minutes. Preferably, in step 3, the specific process of mixing and stirring after uniform mixing is as follows: first, cassava starch is mixed with deionized water and stirred at 50-55℃ for 10 minutes until the starch is completely dissolved; then epichlorohydrin and montmorillonite are added, the temperature is raised to 60-65℃ and stirred for 30 minutes; finally, Artemisia argyi extract is added, the temperature is lowered to 45-50℃ and stirred for 20 minutes to obtain the adhesive layer slurry; in step 4, the coating amount of the roller coater is 20-25 g / m². 2 The thickness of the antibacterial composite coating after application is controlled to be 8-12μm.

[0014] Preferably, in step 4, the specific conditions for segmented drying are as follows: the first stage drying temperature is 60-65℃ and the drying time is 5 minutes; the second stage drying temperature is 70-75℃ and the drying time is 3 minutes; the third stage drying temperature is 50-55℃ and the drying time is 2 minutes; the moisture content of the antibacterial composite coating after drying is ≤1.5%; in step 5, the coating amount of the adhesive layer slurry is 20-22 g / m³. 2 The pressing machine has a pressing temperature of 80-85℃, a pressing pressure of 0.3-0.5MPa, and a pressing time of 3-5 seconds. The corrugated core layer has a basis weight of 100-120g / m². 2 The pre-treated face paper and backing paper both have a basis weight of 120-150 g / m². 2 .

[0015] Preferably, when preparing the environmentally friendly antibacterial corrugated cardboard for the inner layer 7, step 5, after compression molding, also includes an "inner layer lamination" step: a breathable antibacterial film with a thickness of 5-8 μm, made by blending sodium alginate and chitosan, is laminated to the side of the base paper layer away from the second adhesive layer using a low-temperature laminator, with a lamination temperature of 40-45℃ and a lamination pressure of 0.2-0.3 MPa; and step 5, after compression molding, also includes a cutting step, after which the edge crush strength of the environmentally friendly antibacterial corrugated cardboard is ≥20 kN / m, and the antibacterial rate against Escherichia coli is ≥99%.

[0016] (III) Beneficial Effects This invention provides an environmentally friendly antibacterial corrugated cardboard and its surface treatment process. It has the following beneficial effects: (1) By using natural or bio-based raw materials such as Artemisia argyi extract, chitosan, and bio-based polyurethane emulsion, there is no chemical antibacterial agent residue, the VOC content is ≤50g / L, which meets the requirements of environmentally friendly packaging, can be naturally degraded, and is environmentally friendly.

[0017] (2) Through the triple antibacterial design of “pretreatment agent + antibacterial composite coating + antibacterial adhesive layer”, Artemisia argyi extract, chitosan and nano zinc oxide work together to improve the antibacterial rate of common microorganisms such as Escherichia coli and Penicillium, the antibacterial effect is long-lasting, and the antibacterial components are distributed in each layer of the cardboard to achieve all-dimensional antibacterial protection.

[0018] (3) The adhesive layer is cross-linked with epichlorohydrin and montmorillonite is added, which significantly improves the adhesive strength and avoids delamination in humid environments; the bio-based polyurethane emulsion in the antibacterial composite coating works synergistically with sodium alginate to improve the water resistance of the coating, while the corrugated core layer is made of kraft paper to ensure the edge crush strength of the paperboard and excellent physical properties. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of the corrugated cardboard structure of the present invention.

[0020] In the diagram: 1-Antibacterial composite coating, 2-Pre-treated face paper layer, 3-First adhesive layer, 4-Corrugated core layer, 5-Second adhesive layer, 6-Back paper layer, 7-Inner layer. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figure 1 This invention provides a technical solution: an environmentally friendly antibacterial corrugated cardboard, characterized in that it comprises, from the outside to the inside: 1. Antibacterial composite coating, 2. Pre-treated face paper layer, 3. First adhesive layer, 4. Corrugated core layer, 5. Second adhesive layer, and 6. Backing paper layer; The antibacterial composite coating 1 is composed of 60-70 parts by weight of bio-based polyurethane emulsion, 5-8 parts by weight of nano zinc oxide, 2-3 parts by weight of sodium alginate, 2-4 parts by weight of polyethylene glycol 400, 0.5-1 parts by weight of sodium dodecylbenzene sulfonate and 18-25 parts by weight of deionized water. Both the pretreated face paper layer 2 and the back paper layer 6 are base papers containing a pretreatment agent. The pretreatment agent consists of 5-10 parts of Artemisia argyi extract, 3-5 parts of chitosan, 1-2 parts of glycerin, 85-92 parts of deionized water and 0.3-0.5 parts of citric acid by weight. The base paper is made by mixing softwood pulp and waste paper pulp in a mass ratio of 7:3. The first adhesive layer 3 and the second adhesive layer 5 are composed of 100 parts by weight of cassava starch, 2-3 parts of epichlorohydrin, 3-5 parts of montmorillonite, 2-4 parts of Artemisia argyi extract and 300-350 parts of deionized water.

[0023] It also includes an inner layer 7 disposed on one side of the base paper layer 6, the inner layer 7 being a breathable antibacterial membrane.

[0024] The breathable and antibacterial membrane of the inner layer 7 is made of sodium alginate and chitosan, with a thickness of 5-8 μm.

[0025] The corrugated core layer 4 is made of kraft paper in A- or C-type corrugated form, and its basis weight is 100-120 g / m². 2 The basis weight of both the pretreated face paper layer 2 and the back paper layer 6 is 120-150 g / m². 2 The thickness of the antibacterial composite coating 1 is 8-12 μm, and the particle size of the nano zinc oxide is 50-100 nm.

[0026] A surface treatment process for preparing the above-mentioned environmentally friendly antibacterial corrugated cardboard includes the following steps: Step 1: Pretreatment of base paper: Weigh out 5-10 parts by weight of Artemisia argyi extract, 3-5 parts by weight of chitosan, 1-2 parts by weight of glycerin, 85-92 parts by weight of deionized water, and 0.3-0.5 parts by weight of citric acid. Mix them evenly to prepare a pretreatment agent. After filtering the pretreatment agent, spray it on both sides of the base paper made of a mixture of softwood pulp and waste paper pulp at a mass ratio of 7:3 using a sprayer. The spraying amount is controlled at 15-20 g / m². 2 The sprayed base paper is then dried to obtain pretreated face paper layer 2 and base paper layer 6. The pretreatment agent is filtered through an 80-mesh filter, and the pH value of the pretreatment agent is adjusted to 5.5-6.5 with citric acid. Drying is carried out using a dryer at a temperature of 45-55℃ for 5-8 minutes. After drying, the moisture content of both the pretreated face paper and base paper is controlled at 8-10%. Step 2: Preparation of antibacterial composite coating: Weigh out 60-70 parts by weight of bio-based polyurethane emulsion, 5-8 parts by weight of nano zinc oxide, 2-3 parts by weight of sodium alginate, 2-4 parts by weight of polyethylene glycol 400, 0.5-1 parts by weight of sodium dodecylbenzene sulfonate, and 18-25 parts by weight of deionized water; first, mix and stir the deionized water and sodium dodecylbenzene sulfonate, then add the nano zinc oxide and stir before ball milling. Next, add the bio-based polyurethane emulsion, sodium alginate, and polyethylene glycol 400 in sequence and stir to adjust the viscosity of the system to obtain antibacterial composite coating 1. The mixing and stirring of deionized water and sodium dodecylbenzenesulfonate was carried out using high-speed stirring at a speed of 800-1000 r / min for 5 minutes; after adding nano-zinc oxide and stirring, ball milling was performed for 15 minutes, followed by ball milling for 20-30 minutes, with the particle size of the nano-zinc oxide controlled at 50-100 nm after ball milling; the addition of bio-based polyurethane emulsion, sodium alginate, and polyethylene glycol 400 was carried out using low-speed stirring at a speed of 300-500 r / min for 20 minutes. Step 3: Preparation of adhesive layer: Weigh 100 parts of cassava starch, 2-3 parts of epichlorohydrin, 3-5 parts of montmorillonite, 2-4 parts of Artemisia argyi extract, and 300-350 parts of deionized water according to the following weight proportions. Mix them evenly and stir to react, to obtain the raw materials for the first adhesive layer 3 and the second adhesive layer 5 slurry. The specific process of mixing and stirring is as follows: First, mix cassava starch with deionized water and stir at 50-55℃ for 10 minutes until the starch is completely dissolved. Then add epichlorohydrin and montmorillonite, heat to 60-65℃ and stir for 30 minutes. Finally, add Artemisia argyi extract, cool to 45-50℃ and stir for 20 minutes to obtain the adhesive layer slurry. Step 4: Coating and Drying: The antibacterial composite coating obtained in Step 2 is applied to the outer surface of the pretreated paper obtained in Step 1 using a roller coater. The coated pretreated paper is then dried in sections. The coating amount using the roller coater is 20-25 g / m². 2 The thickness of the antibacterial composite coating after application is controlled at 8-12 μm; the specific conditions for segmented drying are as follows: the first stage drying temperature is 60-65℃ and the drying time is 5 minutes; the second stage drying temperature is 70-75℃ and the drying time is 3 minutes; the third stage drying temperature is 50-55℃ and the drying time is 2 minutes; the moisture content of the antibacterial composite coating after drying is ≤1.5%; Step 5: Pressing and Forming: The adhesive layer slurry obtained in Step 3 is coated onto the upper and lower flutes of the corrugated core layer 4 to form the first adhesive layer and the second adhesive layer. Then, the pre-treated face paper coated with an antibacterial composite layer, the first adhesive layer, the corrugated core layer, the second adhesive layer, and the base paper layer are stacked in the following order and fed into a press machine for pressing under the set temperature and pressure to obtain environmentally friendly antibacterial corrugated cardboard. The coating amount of the adhesive layer slurry is 20-22 g / m². 2 The pressing temperature of the press is 80-85℃, the pressing pressure is 0.3-0.5MPa, the pressing time is 3-5 seconds, and the basis weight of the corrugated core layer is 100-120g / m². 2 The pre-treated face paper and backing paper both have a basis weight of 120-150 g / m². 2 When preparing the environmentally friendly antibacterial corrugated cardboard with inner layer 7, step 5, after compression molding, also includes an "inner layer lamination" step: a breathable antibacterial film with a thickness of 5-8 μm, made by blending sodium alginate and chitosan, is laminated to the side of the base paper layer away from the second adhesive layer using a low-temperature laminator. The lamination temperature is 40-45℃ and the lamination pressure is 0.2-0.3MPa. Step 5, after compression molding, also includes a cutting step. After cutting, the edge crush strength of the environmentally friendly antibacterial corrugated cardboard is ≥20kN / m, and the antibacterial rate against Escherichia coli is ≥99%.

[0027] When preparing the basic type, 1. Raw material preparation: Raw materials for antibacterial composite coating: 65 parts bio-based polyurethane emulsion, 6 parts nano zinc oxide, 2.5 parts sodium alginate, 3 parts polyethylene glycol 400, 0.8 parts sodium dodecylbenzene sulfonate, and 21 parts deionized water; Pretreatment agent raw materials: 7 parts Artemisia argyi extract, 4 parts chitosan, 1.5 parts glycerin, 88 parts deionized water, and 0.4 parts citric acid; Adhesive layer raw materials: 100 parts cassava starch, 2.5 parts epichlorohydrin, 4 parts montmorillonite, 3 parts Artemisia argyi extract, 320 parts deionized water; Base paper: made from a 7:3 mixture of softwood pulp and waste paper pulp, with a basis weight of 130 g / m³. 2 ; Corrugated core layer: A-type corrugated paper made of kraft paper, 110g / m² 2 .

[0028] 2. Production process: Paper pretreatment: Prepare the pretreatment agent according to the specified ratio, adjust the pH to 6.0, filter through an 80-mesh filter, and spray it onto the paper at a rate of 18 g / m². 2 Dry at 48℃ for 6 minutes, with the moisture content controlled at 9%; Preparation of antibacterial composite coating: Following the process described in step 2, stir at high speed for 5 minutes, stir nano zinc oxide for 15 minutes, ball mill for 25 minutes, stir at low speed for 20 minutes, and adjust the viscosity to 28 mPa·s. Adhesive layer preparation: Following the process described in step 3, dissolve starch at 52°C, crosslink at 62°C for 30 minutes, and add Artemisia argyi extract at 48°C and stir for 20 minutes. Coating and drying: Roller coater coating amount 22g / m² 2 The coating was dried in stages: 5 minutes at 62℃, 1 minute at 72℃, and 2 minutes at 52℃, resulting in a moisture content of 1.2%. Compression molding: Adhesive layer slurry coating amount 21g / m 2 The product is pressed at 82℃ and 0.4MPa for 4 seconds, and then cut to obtain the finished product.

[0029] 3. Performance Testing: Antibacterial properties: 99.5% inhibition rate against Escherichia coli and 99.2% inhibition rate against Penicillium; Physical properties: edge crush strength 22.5 kN / m, bursting strength 2350 kPa; Water resistance: Surface water absorption rate 4.2%.

[0030] When preparing an inner-layer type, 1. Raw material preparation: The preparation of antibacterial composite coating, pretreatment agent, adhesive layer, base paper, and corrugated core layer raw materials follows the same basic operation. Inner layer material: Sodium alginate and chitosan are blended in a mass ratio of 1:1 to form a breathable antibacterial membrane with a thickness of 6μm.

[0031] 2. Production process: Steps 1-5 are the same as the preparation of the basic model; Inner layer bonding: After compression molding, the breathable antibacterial film is bonded to one side of the base paper layer at 42℃ and 0.25MPa.

[0032] 3. Performance Testing: Antibacterial properties: 99.8% inhibition rate against Escherichia coli and 99.5% inhibition rate against Penicillium; Physical properties: edge crush strength 21.8 kN / m, burst strength 2300 kPa; Breathability: 350cm³ 3 / (m 2 •s).

[0033] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An environmentally friendly antibacterial corrugated cardboard, characterized in that, From the outside in, the following are included: Antibacterial composite coating (1), pretreated face paper layer (2), first adhesive layer (3), corrugated core layer (4), second adhesive layer (5) and back paper layer (6); The antibacterial composite coating (1) is composed of 60-70 parts by weight of bio-based polyurethane emulsion, 5-8 parts by weight of nano zinc oxide, 2-3 parts by weight of sodium alginate, 2-4 parts by weight of polyethylene glycol 400, 0.5-1 parts by weight of sodium dodecylbenzene sulfonate and 18-25 parts by weight of deionized water. The pretreated face paper layer (2) and the back paper layer (6) are both base paper containing a pretreatment agent. The pretreatment agent is composed of 5-10 parts of Artemisia argyi extract, 3-5 parts of chitosan, 1-2 parts of glycerin, 85-92 parts of deionized water and 0.3-0.5 parts of citric acid by weight. The base paper is made by mixing softwood pulp and waste paper pulp in a mass ratio of 7:

3. The first adhesive layer (3) and the second adhesive layer (5) are composed of 100 parts by weight of cassava starch, 2-3 parts of epichlorohydrin, 3-5 parts of montmorillonite, 2-4 parts of Artemisia argyi extract and 300-350 parts of deionized water.

2. The environmentally friendly antibacterial corrugated cardboard according to claim 1, characterized in that: It also includes an inner layer (7) disposed on one side of the base paper layer (6), the inner layer (7) being a breathable antibacterial membrane.

3. The environmentally friendly antibacterial corrugated cardboard according to claim 2, characterized in that: The breathable antibacterial membrane of the inner layer (7) is made of sodium alginate and chitosan and has a thickness of 5-8 μm.

4. The environmentally friendly antibacterial corrugated cardboard according to claim 1, characterized in that: The corrugated core layer (4) is made of kraft paper in type A or type C corrugation, and the basis weight of the corrugated core layer (4) is 100-120 g / m². 2 The basis weight of the pretreated face paper layer (2) and the back paper layer (6) is 120-150 g / m². 2 .

5. The environmentally friendly antibacterial corrugated cardboard according to claim 1, characterized in that: The thickness of the antibacterial composite coating (1) is 8-12 μm, and the particle size of the nano zinc oxide is 50-100 nm.

6. A surface treatment process for preparing environmentally friendly antibacterial corrugated cardboard as described in any one of claims 1-5, characterized in that: Includes the following steps: Step 1: Pretreatment of base paper: Weigh out 5-10 parts by weight of Artemisia argyi extract, 3-5 parts by weight of chitosan, 1-2 parts by weight of glycerin, 85-92 parts by weight of deionized water, and 0.3-0.5 parts by weight of citric acid. Mix them evenly to prepare a pretreatment agent. After filtering the pretreatment agent, spray it on both sides of the base paper made of a mixture of softwood pulp and waste paper pulp at a mass ratio of 7:3 using a sprayer. The spraying amount is controlled at 15-20 g / m². 2 The sprayed base paper is then dried to obtain pretreated face paper layer 2 and base paper layer 6. Step 2: Preparation of antibacterial composite coating: Weigh out 60-70 parts by weight of bio-based polyurethane emulsion, 5-8 parts by weight of nano zinc oxide, 2-3 parts by weight of sodium alginate, 2-4 parts by weight of polyethylene glycol 400, 0.5-1 parts by weight of sodium dodecylbenzene sulfonate, and 18-25 parts by weight of deionized water; first mix and stir the deionized water and sodium dodecylbenzene sulfonate, then add the nano zinc oxide and stir, followed by ball milling. Then add the bio-based polyurethane emulsion, sodium alginate, and polyethylene glycol 400 in sequence and stir to adjust the viscosity of the system to obtain antibacterial composite coating 1; Step 3: Preparation of adhesive layer: Weigh 100 parts of cassava starch, 2-3 parts of epichlorohydrin, 3-5 parts of montmorillonite, 2-4 parts of Artemisia argyi extract and 300-350 parts of deionized water according to the weight ratio, mix them evenly and stir to react, and obtain the raw materials for the first adhesive layer 3 and the second adhesive layer 5 slurry. Step 4: Coating and drying: The antibacterial composite coating obtained in step 2 is coated onto the outer surface of the pretreated paper obtained in step 1 using a roller coater, and then the coated pretreated paper is dried in sections. Step 5: Pressing and forming: The adhesive layer slurry obtained in step 3 is applied to the upper and lower flutes of the corrugated core layer 4 to form the first adhesive layer and the second adhesive layer; then the pre-treated face paper coated with antibacterial composite coating, the first adhesive layer, the corrugated core layer, the second adhesive layer and the bottom paper layer are stacked in the order of stacking and pressing, and then fed into the press machine to press under the set temperature and pressure to obtain environmentally friendly antibacterial corrugated cardboard.

7. The surface treatment process for environmentally friendly antibacterial corrugated cardboard according to claim 6, characterized in that: In step 1, the pretreatment agent is filtered through an 80-mesh filter and the pH value of the pretreatment agent is adjusted to 5.5-6.5 with citric acid. The drying is carried out using a dryer at a temperature of 45-55℃ for 5-8 minutes. After drying, the moisture content of the pretreated face paper and back paper is controlled to be 8-10%.

8. The surface treatment process for environmentally friendly antibacterial corrugated cardboard according to claim 6, characterized in that: In step 2, the deionized water and sodium dodecylbenzenesulfonate are first mixed and stirred at high speed (800-1000 rpm) for 5 minutes. After adding nano-zinc oxide and stirring, the mixture is ball-milled for 15 minutes and 20-30 minutes. The particle size of the nano-zinc oxide after ball milling is controlled to be 50-100 nm. Then, bio-based polyurethane emulsion, sodium alginate, and polyethylene glycol 400 are added sequentially at low speed (300-500 rpm) for 20 minutes.

9. The surface treatment process for environmentally friendly antibacterial corrugated cardboard according to claim 6, characterized in that: In step 3, the specific process of mixing and stirring after homogenization is as follows: First, cassava starch is mixed with deionized water and stirred at 50-55℃ for 10 minutes until the starch is completely dissolved. Then, epichlorohydrin and montmorillonite are added, and the temperature is raised to 60-65℃ and stirred for 30 minutes. Finally, Artemisia argyi extract is added, and the temperature is lowered to 45-50℃ and stirred for 20 minutes to obtain the adhesive layer slurry. In step 4, the coating amount of the roller coater is 20-25 g / m². 2 The thickness of the antibacterial composite coating after application is controlled to be 8-12μm.

10. The surface treatment process for environmentally friendly antibacterial corrugated cardboard according to claim 6, wherein in step 4, the specific conditions for segmented drying are as follows: the first segment drying temperature is 60-65℃ and the drying time is 5 minutes; the second segment drying temperature is 70-75℃ and the drying time is 3 minutes; the third segment drying temperature is 50-55℃ and the drying time is 2 minutes; the moisture content of the antibacterial composite coating after drying is ≤1.5%; in step 5, the coating amount of the adhesive layer slurry is 20-22 g / m². 2 The pressing machine has a pressing temperature of 80-85℃, a pressing pressure of 0.3-0.5MPa, and a pressing time of 3-5 seconds. The corrugated core layer has a basis weight of 100-120g / m². 2 The pre-treated face paper and backing paper both have a basis weight of 120-150 g / m². 2 .

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