A recycled board based on recycled waste paper packaging material and a method for producing the same

Abstract

The application provides a kind of recycled board based on recycled waste paper packaging material and a preparation method thereof, comprising the following steps: first, using softening liquid to soak and soften the paper packaging material;Second, the product after softening is washed to neutral, broken to obtain slurry, and the water is squeezed out to obtain paper mud;Finally, the paper mud is step-by-step hot-pressed to obtain a recycled board.The preparation method of the recycled board provided by the application does not need to pulp and deink the recycled paper packaging material, only needs to swell and separate the biomass fiber through simple chemical treatment, and the fiber is also dispersed, and a fiber-reinforced composite material is obtained by hot pressing and molding process.The process of the application is simple, the cost is low, the mechanical properties and thermal properties of the board obtained by hot pressing are good, the water stability is high, zero formaldehyde is released, and the application has the advantages of sustainable recycling, low carbon emission, etc., and has broad application prospect and is suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the technical field of value-added utilization of paper packaging materials, specifically relating to a recycled board material based on recycled waste paper packaging materials and its preparation method. Background Technology

[0002] Paper packaging materials are a large-scale, widely used material, including corrugated cardboard, paper bags, cardboard, and sandpaper. They play a vital role in various industries, from food packaging to everyday consumer goods, and are widely favored for their lightweight and environmentally friendly characteristics. However, their large-scale use also leads to significant waste, as paper packaging has not been adequately recycled and reused in practice. The abundant cellulose resources contained in paper packaging have enormous potential value. If an effective recycling and reuse mechanism can be implemented, it is hoped that these resources can be transformed into valuable resources for sustainable development.

[0003] Taking corrugated cardboard, a typical paper packaging material, as an example, corrugated boxes are widely used in packaging and transportation due to their advantages such as low cost, light weight, high strength, and ease of transportation, making them the most widely used packaging product. my country consumes a huge amount of corrugated boxes, reaching 42.4 million tons in 2023. However, these boxes are widely dispersed, leading to high recycling costs and low recycling quality. Currently, the recycling rate is less than 20%, resulting in significant waste.

[0004] Traditional recycling methods primarily involve compressing and packaging corrugated cardboard boxes, transporting them to recycling plants, where they are softened by soaking in water and then stirred into pulp. The pulp is bleached, a strengthening agent is added, and it undergoes dehydration, high-temperature drying, and other steps to reconstitute it into cardboard, which is then cut and laminated to obtain the finished product. However, this recycling method is complex and time-consuming, and waste remains after cutting the cardboard, resulting in waste. Furthermore, separating and recycling plastic sheeting is difficult. Recycled paper produced using this process also has drawbacks. The production of recycled paper requires specialized equipment and processes, increasing its price. Recycled paper itself often has characteristics such as spots, low brightness, and dull color, making it difficult to meet the requirements for high-quality paper and limiting its applicability.

[0005] In view of the above-mentioned technical shortcomings, developing a new method and materials for the high-value utilization of waste paper packaging materials that are simple in steps, low in cost and energy consumption, environmentally friendly, easy to mass-produce, and produce high-performance products is the focus of research in this field.

[0006] Currently, the main types of boards on the market include MDF (medium-density fiberboard) and particleboard. These boards are engineered wood products made primarily from wood fibers or wood chips, bonded together with adhesives under heat and pressure. However, these boards have low overall strength and poor moisture resistance, making them unsuitable for excessively humid environments or places subjected to high stress. Furthermore, because urea-formaldehyde resin is added during the manufacturing process, it releases formaldehyde during use, resulting in poor environmental friendliness and posing a threat to human health.

[0007] Based on this, a simple and environmentally friendly new method for recycling paper packaging waste is provided, opening up a new path for recycling and remanufacturing paper packaging waste represented by corrugated paper. The resulting products are green, environmentally friendly, widely used, and easy to promote. This method can not only significantly improve the recycling rate of paper packaging waste, but also has important significance for the sustainable development of resource materials. Summary of the Invention

[0008] One of the objectives of this invention is to provide a method for preparing recycled board based on recycled waste paper packaging materials that is low in cost and energy consumption, environmentally friendly, easy to mass-produce, and has excellent product performance.

[0009] The second objective of this invention is to provide a recycled board material based on recycled waste paper packaging materials that has good mechanical stability, thermal stability, water resistance, degradability, and easy recycling.

[0010] One of the technical solutions adopted to achieve the objective of this invention is: providing a method for preparing recycled board material based on recycled waste paper packaging material, comprising the following steps:

[0011] S1. The recycled waste paper packaging material is soaked in a softening solution for softening treatment to obtain the first product;

[0012] S2. Wash the first product until the pH is neutral, crush it to obtain a slurry, and squeeze out the water from the slurry to obtain the second product.

[0013] S3. The second product is hot-pressed. First, it is hot-pressed at 30-50MPa and 60-80℃ for 1-5 hours, then the pressure is increased to 80-100MPa and the temperature is raised to 130-150℃ for 3-10 hours. After cooling, the recycled board is obtained.

[0014] The overall concept and principle of this invention are as follows: Addressing the problems existing in the recycling and processing of waste paper packaging materials, this invention provides a method for preparing recycled boards based on waste paper packaging materials. Through paper packaging recycling, chemical treatment, mechanical stirring, and hot pressing, high-strength recycled boards are prepared without the addition of other polymers. The above preparation method can be carried out using common equipment, is simple and efficient, and the prepared boards have advantages such as being environmentally friendly, low-cost, and widely applicable, and can be used in various fields such as home furnishings and building materials.

[0015] In the above preparation method, firstly, waste paper packaging material is soaked in a softening solution, causing the fibers to swell and resulting in higher flexibility. Secondly, through mechanical stirring, the fibers in the paperboard are broken up and cut, reducing fiber length and causing the fiber surface to fibrillate to increase the specific surface area and the bonding area between fibers. Finally, under high temperature and high pressure conditions, water molecules in the paper pulp are squeezed out, and the gaps between fibers are compressed to a very small size. The pressure provides the energy required for the movement of cellulose molecules. Under extremely high pressure, cellulose molecules come into contact with each other and form a large number of hydrogen bonds, which endows the board with excellent mechanical properties.

[0016] The hot-pressing process in step S3 is a crucial step in this preparation method. The selection of pressure, temperature, and time during hot pressing determines the degree of reaction within the material and also promotes the improvement of the mechanical strength, thermal stability, and fire resistance of the final hot-pressed product. The cardboard contains abundant lignin, and the internal bonding strength of the board is mainly due to the formation of new CC bonds in lignin during hot pressing. Preliminary chemical treatment (softening treatment) and mechanical stirring can break β-O-4' bonds and α-O-4 bonds in the lignin macromolecules, partially depolymerizing the lignin. Subsequent hot pressing at higher temperatures breaks the aromatic ether bonds in the lignin, especially the β-O-4' bonds, releasing ether radicals and phenol radicals. These radicals couple with the quinoline ether intermediate to produce new β-O-4' substructures and CC bonds, such as β-5', β-β, and β-1' bonds. The formation of these new CC bonds is the main reason for the strong internal bonding strength of the board. During hot pressing, lignin accumulates on the hydrophobic surface of cellulose, acting as a binder between fibers, resulting in extremely low porosity between fibers and tight bonding between them. As a result, the material has good hydrophobicity, stability and mechanical properties.

[0017] In step S3, appropriate pressure not only affects the molecular arrangement and orientation within the raw material, increasing the physical entanglement between cellulose fibers, but also generates a certain thermal effect, accelerating the thermal degradation and cross-linking reactions within the raw material. In this invention, the initial hot-pressing pressure is 30-50 MPa for 1-5 hours, and the secondary hot-pressing pressure is 80-100 MPa for 3-10 hours. Under the high pressure of these two hot-pressing stages, the cellulose molecular chains rearrange and orient, forming a more regular structure. This orientation helps to form more hydrogen bonds, thereby improving the structural integrity and mechanical properties of the material. Furthermore, when pressure is applied, the physical entanglement between cellulose fibers increases, which enhances the cohesive force of the material and reduces microscopic defects within the material, such as cracks and voids. Simultaneously, high pressure also leads to a local temperature increase in the material, thereby accelerating thermal degradation or cross-linking reactions. This thermal effect can alter the chemical cross-linking density of the material and affect its physical and chemical properties. This invention improves the mechanical strength and reduces the porosity of materials by controlling the pressure of hot pressing, making the materials harder and more durable. The high-pressure process also improves the chemical stability and water resistance of the materials, reduces the ability of water molecules or other chemicals to penetrate the products, and the denser structure of the high-pressure treated boards can reduce the transmission of heat through the materials, thereby achieving higher thermal stability.

[0018] Furthermore, in hot pressing, if the hot pressing temperature is too high, the product may turn yellow and scorch, and the paper scraps may saccharify, making it difficult to demold. Conversely, if the hot pressing temperature is too low, the drying effect of hot pressing will not be achieved, resulting in a high moisture content in the product, which will affect its strength and application performance. In this invention, a step-by-step hot pressing method is adopted. First, hot pressing is performed at 30-50 MPa and 60-80℃ for 1-5 hours to evaporate moisture. Then, the pressure is increased to 80-100 MPa and the temperature is raised to 130-150℃ for 3-10 hours to ensure the quality of the final board. Specifically, the hot pressing temperature, time, and strength can be appropriately adjusted according to the amount of raw materials used, the actual production effect, and the performance requirements of the product.

[0019] Furthermore, in step S1, the recycled waste paper packaging materials include one or more combinations of corrugated cardboard, kraft paper bags, gift boxes, and file boxes. These recycled waste paper packaging materials come from a wide range of sources, including express delivery packaging, transport packaging, and product packaging.

[0020] Further, in step S1, the softening liquid includes one or more combinations of an aqueous solution of an alkali, a reducing salt solution, a eutectic solvent, and an ionic liquid. In this invention, the softening liquid is used to chemically treat recycled waste paper packaging materials, thereby softening the material by altering the interactions between cellulose molecules, reducing its crystallinity, removing or changing accompanying components (such as lignin), and increasing the overall flexibility and plasticity of the material.

[0021] Preferably, the aqueous solution of the alkali includes one or more combinations of sodium hydroxide solution, potassium hydroxide solution, and ammonia solution; the reducing salt solution includes one or more combinations of aqueous solutions of sodium sulfide, sodium sulfite, sodium bisulfite, calcium bisulfite, magnesium bisulfite, and ammonium sulfite; the eutectic solvent includes one or more combinations of choline chloride-urea, choline chloride-glycerol, acetic acid-urea, and zinc chloride-urea; and the ionic liquid includes one or more combinations of 1-ethyl-3-methylimidazolium acetate and (1-butyl-3-methylimidazolium) chloride.

[0022] In the aforementioned softening solution, alkaline solutions such as sodium hydroxide can react with the hydroxyl groups in cellulose, disrupting its hydrogen bond network. This action leads to the relaxation of the cellulose structure, thereby softening the material. Simultaneously, the alkaline aqueous solution can also partially remove stiff components from lignin and hemicellulose, further promoting the overall softening of the material.

[0023] Reducing salt solutions such as sulfite solutions are mainly used for bleaching and lignin removal of materials. They can break the chemical bonds between lignin and cellulose, reducing the rigidity of wood and fiber materials and increasing their softness. Sodium sulfite can also reduce some cross-links in cellulose, further leading to a softening effect.

[0024] Eutectic solvents (DES) are mixtures formed by two or more components through hydrogen bonding. They have excellent dissolving power for cellulose, penetrating its microstructure and disrupting the internal hydrogen bonds. This disruption loosens the fiber structure, thus achieving a softening effect.

[0025] The softening effect of ionic liquids on materials is mainly due to their unique solvent properties; they can dissolve cellulose and alter its supramolecular structure. The cations and anions in ionic liquids can engage in complex interactions with the hydroxyl groups in cellulose molecules, changing their crystallinity and structural arrangement, thereby softening the cellulose.

[0026] Furthermore, the concentration of the softening solution is 0.3-3 mol / L, and the volume ratio of the softening solution to the recycled waste paper packaging material is (100-150):(50-100) mL / cm³. 3 The softening process takes 1-5 hours.

[0027] Preferably, the concentration of the aqueous solution of the alkali is 0.3-2.5 mol / L, and the softening treatment time is 1-3 hours; the concentration of the sulfite solution is 0.4-2.5 mol / L, and the softening treatment time is 2-4 hours; the concentration of the eutectic solvent (DES) is 1-2.5 mol / L, and the softening treatment time is 3-5 hours; the concentration of the ionic liquid is 0.3-2 mol / L, and the treatment time is 3-5 hours.

[0028] Preferably, the softening solution after softening treatment in step S1 is recycled and reused. The softening treatment of the preparation method of the present invention does not require the addition of other reagents, and the softening solution can be reused more than 20 times after recycling. Compared with the complex recycling process of commercial boards, it has good environmental sustainability and economic friendliness.

[0029] Furthermore, in step S2, the crushing process is carried out by stirring at a speed of 10,000-30,000 rpm. On the one hand, high-speed stirring further decomposes the softened waste paper, making the fibers finer and more uniform; on the other hand, the crushing process increases the specific surface area of ​​the fibers, allowing the finer fibers to better intertwine and combine during the subsequent hot pressing process, thereby improving the mechanical strength and durability of the board.

[0030] Furthermore, the mixing time should not be too long. Excessive mixing can lead to fiber breakage or excessive shortening, making the fibers brittle and affecting the strength and durability of the board. In addition, prolonged mixing also increases time costs and energy consumption. Preferably, the mixing time is 1-3 minutes.

[0031] Preferably, in step S2, the slurry obtained from the crushing process is poured into a filter cloth, the filter cloth is used to wrap the slurry, and then the water in the slurry is squeezed out. The filter cloth has a mesh size of 200-500.

[0032] Preferably, in step S3, the second product is placed in a suitable mold and then hot-pressed. The shape of the mold is not limited and can be molded into various complex shapes according to the requirements of the product.

[0033] Preferably, in step S3, after the recycled board is removed from the mold, it is post-processed using a high-speed grinder to correct it, achieving a smooth and neat surface, and realizing a more refined processing and finishing effect.

[0034] A second objective of this invention is to provide a recycled board material prepared by the preparation method described in one of the objectives of this invention.

[0035] The recycled board material provided by this invention uses waste paper packaging materials as raw material, resulting in lower costs. It also offers a new pathway for waste resource utilization, helping to reduce environmental burden and contributing positively to energy conservation and emission reduction. The preparation method provided by this invention has a low carbon footprint, requiring no complex processes, high energy consumption, or high costs. Compared to conventional board manufacturing processes, it offers significant economic and environmental benefits. The prepared board material exhibits significant advantages in mechanical properties compared to commercially available MDF and particleboard, while releasing almost no formaldehyde, making it more environmentally friendly, green, and healthy.

[0036] Furthermore, the recycled board provided by this invention also has good biodegradability. The cellulose in the waste board can be naturally decomposed into nutrients by the decomposition and metabolism of microorganisms in the soil and enter the carbon cycle ecosystem.

[0037] In some preferred embodiments, the recycled board obtained by the present invention has a tensile stress of 31.6-55.3 MPa, a bending stress of 66.1-87.2 MPa, and a compressive stress of 280.2-330.1 MPa.

[0038] In some preferred embodiments, the recycled board prepared by the present invention shows no obvious deformation when heated at 220°C for 10 minutes; the limiting oxygen index of the recycled board is greater than 27%, it is not a flammable material, and it has a certain flame retardancy; its absorption rate (weight percentage) is 3% to 8% after 24 hours under a relative humidity of 97%, and its water absorption thickness expansion rate is 2% to 5%.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] 1) The method for preparing recycled board material from recycled paper packaging materials provided by this invention uses widely used and abundant waste paper packaging materials as raw materials, which are inexpensive and readily available. The preparation process requires no complex procedures or binders, resulting in high economic efficiency and a low carbon footprint. The preparation process is simple, with low operating costs, and can be mass-produced, making it suitable for large-scale industrial production.

[0041] 2) The method for preparing recycled boards using recycled paper packaging materials provided by the present invention does not require sorting, pulping, deinking, or separating plastic tape from the recycled packaging. It softens, crushes, and presses the recycled boards through simple chemical treatment, thus avoiding the disadvantages of complex recycling processes and high recycling difficulty in the prior art.

[0042] 3) The recycled board produced by this invention undergoes a step-by-step high-temperature hot-pressing process, resulting in a synergistic effect between cellulose fibers and lignin, thereby increasing the mechanical properties and thermal stability of the board. The mechanical properties (including flexural strength, compressive strength, etc.) of the recycled board are approximately 10 times that of commercial particleboard.

[0043] 4) The recycled board produced by this invention has a certain degree of fire resistance. Compared with particleboard, the recycled board provided by this invention has a certain degree of self-extinguishing property; when the fire source is removed, the flame on the board will stop burning.

[0044] 5) The recycled boards produced by this invention do not contain any urea-formaldehyde resin or other adhesives during the preparation process, resulting in a far lower environmental impact than plywood. They release no formaldehyde, and the formaldehyde emission level is below the E1 national standard, demonstrating high environmental value. The recycled boards produced by this invention can replace materials such as wood and plastics, and have high market value in interior decoration, building materials, and other fields.

[0045] 6) The recycled board provided by this invention has good biodegradability. When buried in natural soil at a depth of 5 cm from the topsoil, the board is almost completely degraded after 12 months, which shows the environmental friendliness of the recycled board.

[0046] 7) The recycled boards provided by this invention have good recyclability. Waste recycled boards can still be remade into recycled boards with a certain strength through physical mechanical stirring, hot pressing, etc. The recycling process is simple and convenient, requiring no additional reagents, and the softening liquid used in the preparation process can be reused more than 20 times. Compared with the complex recycling process of commercial boards, it has good environmental sustainability and economic friendliness. Attached Figure Description

[0047] Figure 1 This is a schematic flowchart of a method for preparing recycled board material using waste paper packaging materials provided by the present invention.

[0048] Figure 2 This is a macroscopic morphological diagram of the recycled board material provided in Embodiment 1 of the present invention;

[0049] Figure 3 This is a macroscopic morphology diagram of the untreated plate material provided in Comparative Example 1 of the present invention;

[0050] Figure 4 This is a macroscopic morphology diagram of the plate material without high pressure provided in Comparative Example 2 of the present invention;

[0051] Figure 5 These are scanning electron microscope images of the recycled board material provided in Embodiment 1 of the present invention; wherein, (a) is a scanning electron microscope image of the cross section of the recycled board material; and (b) is a scanning electron microscope image of the surface of the recycled board material.

[0052] Figure 6 This is a schematic diagram of the flexural modulus of the recycled sheet material provided in Embodiment 1 of the present invention;

[0053] Figure 7This is a schematic diagram of the compression modulus of the recycled sheet material provided in Embodiment 1 of the present invention;

[0054] Figure 8 This is an optical photograph and weight loss curve of a soil degradation experiment of the recycled board material provided in Embodiment 1 of the present invention (buried in natural soil at a depth of 5 cm from the surface soil);

[0055] Figure 9 These are optical photographs of the recycled board material provided in Embodiment 1 of the present invention after being heated under different temperature conditions; wherein, (a) is heated at 25°C for 10 minutes; and (b) is heated at 220°C for 10 minutes.

[0056] Figure 10 This is a flowchart of the recycling process of recycled boards after disposal, as provided in Embodiment 1 of the present invention;

[0057] Figure 11 These are optical photographs of the vertical combustion experiment of the recycled board and particleboard provided in Embodiment 1 of the present invention. Detailed Implementation

[0058] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0059] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0060] like Figure 1 As shown in the flowchart, this invention provides a method for preparing recycled board material using recycled waste paper packaging material, comprising the following steps:

[0061] Step 1: Chemical treatment of recycled waste paper packaging materials

[0062] Mix the softening solution with recycled waste paper packaging material at a volume ratio of (100-150 mL): (50-100 cm³). 3 Mix the ingredients in the specified proportions and soak for 1-5 hours to fully soften and swell the paper fibers, increasing dispersion and fiber bonding. Then wash the paperboard with distilled water until the pH is neutral, add it to a mixer, and use the mixer to shred the waste paper into paper scraps. Pour the scraps into a 200-500 mesh filter cloth to squeeze and dewater the pulp, removing a large amount of water, resulting in paper slurry.

[0063] The recycled board preparation method of this embodiment does not require re-pulping and deinking during the crushing process; it only requires crushing. The process is simple and convenient, and it can preserve the original strength of the paper fibers to the maximum extent. The crushing time in this step should not be too long, and the stirring time should be 1-3 minutes. During the stirring process, the fibers break down into fibrils, the specific surface area increases, and the bonding force between the fibers is enhanced.

[0064] The paper packaging material in this embodiment can be derived from express packaging, transport packaging, product packaging, etc., with a wide range of raw material sources, which can better recycle resources and reduce production costs.

[0065] Step 2: Compression molding

[0066] The paper pulp obtained in step 1 is placed into the required mold, and the mixed paper material is pressed into recycled board under high temperature and high pressure using a vulcanizing machine.

[0067] Paper packaging materials contain lignin, which undergoes self-bonding during hot pressing, coordinating with paper fibers to enhance the mechanical properties of the board and improve the material's water stability. The resulting recycled boards can be easily shaped and demolded, and their strength meets usage requirements.

[0068] In this embodiment, hot pressing is used for mold forming. During the hot pressing and drying process, the hot pressing mold closes and dries the paper pulp, allowing the paper pulp to be dried and pressed under greater pressure. The water in the paper pulp is squeezed out, the gaps between the paper fibers are reduced, and the resulting board is denser, thus improving the strength of the board.

[0069] If the temperature is too high during hot pressing, the product may turn yellow and scorch, and the paper scraps may saccharify, making it difficult to demold. Conversely, if the temperature is too low, the hot pressing will not achieve the desired drying effect, resulting in a high moisture content in the product and affecting its strength. In actual production, hot pressing should first be carried out at around 60-80℃ and 20-30 MPa for 1-5 hours to evaporate the moisture. Then, the temperature should be increased to 130-150℃ and the pressure increased to 80-100 MPa for 3-10 hours. Specifically, the hot pressing temperature, time, and strength can be adjusted appropriately according to the actual production results and the performance requirements of the product.

[0070] Step 3: Sanding and post-treatment

[0071] After the product is removed from the mold, it is polished into the required shape using a high-speed grinder. The edges of the dried molded parts may be uneven and the shape may be irregular. Therefore, a grinder can be used to correct these irregularities, achieving a smooth and neat surface, allowing for more detailed processing and finishing.

[0072] The method for preparing recycled boards from recycled waste paper packaging materials provided in this embodiment does not require separating plastic sheeting, pulping, deinking, or other processes from the recycled cardboard. Instead, it directly combines the paper fibers and adhesives contained in the cardboard itself to form recycled boards that can be used immediately. The process is simple and low-cost, avoiding the disadvantages of existing technologies such as complex procedures, excessive waste, and low utilization rate.

[0073] The softening solution used in the chemical treatment of the paperboard in step 1 of the above preparation method is selected from: sodium hydroxide solution, sodium sulfide aqueous solution, calcium bisulfite aqueous solution, magnesium bisulfite aqueous solution, sodium sulfite aqueous solution, DES eutectic solvent (one of choline chloride-urea, choline chloride-glycerol, acetic acid-urea, and zinc chloride-urea), 1-ethyl-3-methylimidazolium acetate [EMIM][Ac], and (1-butyl-3-methylimidazolium chloride) [BMIM]Cl, and the concentration of the softening solution is 0.3-3 mol / L.

[0074] In step 1 of the above preparation method, the experimental raw material is one of the following paper packaging materials: corrugated cardboard, kraft paper bags, gift boxes, file boxes, etc.

[0075] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention.

[0076] The key parameters of the specific preparation process in each embodiment of the present invention are shown in Table 1 below:

[0077] Table 1 Selection of Raw Materials and Parameters

[0078]

[0079]

[0080] Performance testing

[0081] (I) Mechanical property testing

[0082] The mechanical properties of the recycled boards obtained in the various embodiments and comparative examples of this invention are shown in Table 2 below:

[0083] Table 2 Mechanical properties of recycled boards obtained in each embodiment

[0084]

[0085]

[0086] (II) Heat Resistance Test

[0087] like Figure 9As shown, in this invention, the prepared recycled board (Example 1), POM, PVC, PP and PU were simultaneously heated to 220°C. Observation showed that, except for the recycled board provided in this application, POM, PVC, PP and PU all exhibited a certain degree of melting, which indicates that the board provided in this application has good heat resistance.

[0088] (III) Flame retardant performance test

[0089] As shown in Table 3, the limiting oxygen index test of the recycled board (Example 1) prepared in this invention and the commercial particleboard shows that the recycled board is not a flammable material and has a certain flame retardancy compared to the commercial particleboard.

[0090] Table 3 Limiting Oxygen Index Values ​​for Recycled Boards and Commercial Particleboard

[0091] Flammable materials ≤27 Particleboard 25.2 Recycled boards 27.3

[0092] (iv) Cyclic Regeneration Performance Test

[0093] like Figure 10 As shown, after the prepared board is soaked and softened in a solution and stirred, it is then subjected to hot pressing in the same way, and a high-performance recycled board can still be obtained. This shows that the board has good recyclability and the method has universal applicability.

[0094] (V) Water Resistance Test

[0095] As shown in Table 4, in this invention, the samples of Example 1 and Comparative Examples 1 and 2 were simultaneously placed in an environment with 97% relative humidity, and their volume and weight changes were measured. The results are shown in the table below:

[0096] Table 4. Changes in thickness and weight of the board after water absorption.

[0097] 24h water absorption thickness expansion rate 3.01％ 6.2％ 13.59％ 24h water absorption rate 7％ 12％ 15％

[0098] As can be seen from the table above, the high-strength recycled board provided in this application has very little change in water absorption thickness expansion rate and water absorption rate. This is because under high temperature and high pressure environment, the arrangement between cellulose fibers is more compact, the porosity is reduced, and the density is increased, making it difficult for water molecules to enter, and the water resistance of the board is greatly improved.

[0099] In summary, the recycled board material prepared from recycled waste paper packaging materials provided by this invention undergoes only simple chemical treatment without the addition of any other chemical adhesives. It can naturally degrade in nature and will not cause pollution to the environment. Products made from this recycled board material can be recycled again after being discarded.

[0100] The recycled board produced by this invention has advantages such as inexpensive and readily available raw materials, pollution-free production process, and excellent mechanical and thermal properties, high water stability, zero formaldehyde, low carbon emissions, and easy recyclability and degradation. Therefore, it can be widely used in various packaging and home decoration building materials fields. This recycled board has a certain strength and is aesthetically pleasing. Some items made from it can replace materials such as wood and plastic, making it an excellent substitute. It has broad application prospects in interior decoration, furniture, and other fields, and has high market value. This can promote the utilization and recycling industry of waste paper packaging materials, represented by waste corrugated cardboard, in my country, and improve the recycling rate of waste paper packaging materials.

[0101] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the content of this specification should be included within the protection scope of the present invention.

Claims

1. A type of recycled board material, characterized in that, The tensile stress of the recycled board is 31.6-55.3 MPa, the bending stress is 66.1-87.2 MPa, and the compressive stress is 280.2-330.1 MPa. The recycled board is obtained by the following method: S1. The recycled waste paper packaging material is soaked in a softening solution for softening treatment to obtain the first product; the softening solution is a eutectic solvent or an ionic liquid; S2. Wash the first product until the pH is neutral, crush it to obtain a slurry, and squeeze out the water from the slurry to obtain the second product. S3. The second product is hot-pressed. First, it is hot-pressed at 30-50MPa and 60-80℃ for 1-5 hours, then the pressure is increased to 80-100MPa and the temperature is raised to 130-150℃ for 3-10 hours. After cooling, the recycled board is obtained.

2. The recycled board material according to claim 1, characterized in that, In step S1, the recycled waste paper packaging materials include one or more combinations of corrugated cardboard, kraft paper bags, gift boxes, and file boxes.

3. The recycled board material according to claim 1, characterized in that, In step S1, the concentration of the softening solution is 0.3-3 mol / L.

4. The recycled board material according to claim 1, characterized in that, In step S1, the volume ratio of softening liquid to recycled waste paper packaging material is (100-150):(50-100) mL / cm³. 3 .

5. The recycled board material according to claim 1, characterized in that, In step S1, the softening process takes 1-5 hours.

6. The recycled board material according to claim 1, characterized in that, In step S2, the crushing process is carried out by stirring, with a stirring speed of 10,000-30,000 rpm and a stirring time of 1-3 minutes.

7. The recycled board material according to claim 1, characterized in that, In step S2, the slurry is wrapped with a filter cloth of 200-500 mesh, and then the water contained in the slurry is squeezed out.

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