Foldable logistics turnover box with flame-retardant property

Abstract

The present application relates to the technical field of logistics transportation equipment, and discloses a foldable logistics turnover box with flame-retardant performance, which comprises a box base, a foldable box plate hingedly connected with the box base, a sleeved box cover, a plurality of hand-screwed screws and four groups of anti-collision reinforcing devices arranged at outer corners of the foldable box plate, wherein the foldable box plate is made of a high polymer material with preset structural rigidity and impact toughness; the anti-collision reinforcing devices are made of a metal material and are combined with the outer corners of the foldable box plate to jointly form a plastic-metal composite reinforcing structure for resisting external impact and improving the overall stacking load capacity of the turnover box. Through the synergistic effect of the composite flame retardant with a specific ratio and the various PP recycled materials, the present application solves the safety hazard problem of insufficient flame retardancy of the traditional turnover box, realizes resource recycling, and meets the requirements of safety performance and environmental protection and economy.

Description

Technical Field

[0001] This invention relates to the field of logistics transportation equipment technology, and in particular to a foldable logistics turnover box with flame-retardant properties. Background Technology

[0002] The turnover boxes currently used in the logistics field have significant shortcomings in core performance and adaptability. Most turnover boxes are made of ordinary PP or single recycled PP materials, with low flame retardant ratings, making it difficult to meet the safety requirements for transporting flammable goods such as electronic components and chemical raw materials, as well as high-temperature storage scenarios, and easily causing combustion accidents. Some foldable turnover boxes have unreasonable structural designs, with weak connection strength between the box panels and the base, and lack of anti-collision reinforcement structures. They are prone to deformation and breakage when stacked in multiple layers, with limited load-bearing capacity, and cannot be adapted to the bulk transportation of heavy objects. At the same time, the selection of materials with unoptimized recycled material ratios or inappropriate additives leads to unstable mechanical properties, easy aging, and short service life, which increases costs and does not meet the requirements of green environmental protection.

[0003] Most existing logistics turnover boxes are made of ordinary PP or recycled PP. Although they have certain mechanical properties and foldability, their flame retardant properties are poor, posing safety hazards when transporting flammable materials or in high-temperature environments. While some flame-retardant modified materials exist, most are expensive, have poor processability, and are not integrated with the structural design of the turnover boxes, making it difficult to meet the logistics industry's comprehensive requirements for safety, lightweight, and foldability. Summary of the Invention

[0004] The purpose of this invention is to provide a foldable logistics turnover box with flame-retardant properties, which solves the problem of poor flame-retardant performance.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A foldable logistics turnover box with flame-retardant properties, comprising:

[0007] The box base, the foldable box panel hinged to the box base, the socket-type box cover, multiple hand-tightening screws, and four sets of anti-collision reinforcement devices located at the outer corners of the foldable box panel, wherein the foldable box panel is made of a polymer material with preset structural rigidity and impact toughness.

[0008] The anti-collision reinforcement device is made of metal and is integrated with the outer corners of the foldable box panel to form a plastic-metal composite reinforcement structure, which is used to resist external impacts and improve the overall stacking load-bearing capacity of the turnover box.

[0009] Preferably, the anti-collision reinforcement device is a pluggable triangular metal reinforcement device.

[0010] Preferably, the outer corner of the foldable box panel is provided with a preset groove for accommodating and positioning the anti-collision reinforcement device.

[0011] Preferably, the foldable box panel is hinged to the box base via an integrally injection-molded rotating connecting block.

[0012] Preferably, when multiple turnover boxes are stacked, the socket-type box cover transfers the load of the upper turnover box to the four sets of anti-collision reinforcement devices of this box, and then the load is transferred downward along the four corners of the turnover box through the anti-collision reinforcement devices, forming a rigid vertical load-bearing path.

[0013] A foldable logistics turnover box with flame-retardant properties also includes the following components by weight:

[0014] PP mixed color propylene recycled material: 50-70 parts;

[0015] PP paint bucket recycled material: 5-15 parts;

[0016] PP washing machine recycled material: 5-15 parts;

[0017] PP multi-color cup recycled material: 10-30 parts;

[0018] Composite flame retardant: 1-5 parts;

[0019] Antioxidant: 0.2-1 part;

[0020] Lubricant: 0.5-1 part;

[0021] Pigment: 0.01-0.25 parts;

[0022] The composite flame retardant is prepared by mixing ammonium polyphosphate, 2,3-dimethyl-2,3-diphenylbutane and flame-retardant recycled PP material in a mass ratio of 1-3:0.5-1.5:6-8.

[0023] Preferably, the melt flow index of the flame-retardant recycled PP material in the composite flame retardant is 2-4 g / 10 min, and the notched impact strength is 4-8 kJ / m. 2， Specific gravity is 0.99-1.05 g / cm³ 3 .

[0024] Preferably, the antioxidant is a mixture of 2,6-tert-butyl-4-methylphenol and bis(3,5-tert-butyl-4-hydroxyphenyl) sulfide, and the mass ratio of the two is 0.1-0.5:0.1-0.5.

[0025] A foldable logistics turnover box with flame-retardant properties further includes the following steps:

[0026] a) Provide each raw material component of any flame-retardant recycled PP material composition;

[0027] b) Mix the composite flame retardant with other raw materials except antioxidants and colorants, and granulate them once to obtain primary granules;

[0028] c) The primary granules are mixed with antioxidants and colorants, and then granulated again to obtain the final flame-retardant recycled PP material composition;

[0029] d) Using injection molding or compression molding processes, the flame-retardant recycled PP material composition obtained in step c) is used to prepare the box base, foldable box panel and socketable box cover;

[0030] e) Install a metal anti-collision reinforcement device at the outer corner of the foldable box panel to form a plastic-metal composite reinforcement structure.

[0031] Preferably, the flame-retardant recycled PP material in step a) is obtained through the following steps:

[0032] The composite flame retardant is mixed with other raw materials except antioxidants and colorants, and then granulated once to obtain primary granules.

[0033] The primary granules are mixed with antioxidants and colorants, and then subjected to secondary granulation to obtain the flame-retardant recycled PP material.

[0034] In summary, the present invention has at least one of the following beneficial technical effects:

[0035] 1. This invention utilizes a specific ratio of composite flame retardant and various recycled PP materials to synergistically construct a multi-phase flame retardant mechanism involving the gas phase, condensed phase, and substrate. Ammonium polyphosphate forms a dense char layer at high temperatures to block oxygen heat transfer, while 2,3-dimethyl-2,3-diphenylbutane captures combustion free radicals to interrupt the chain reaction. The flame-retardant recycled PP material optimizes compatibility and mechanical stability, enabling safe transportation of flammable materials or use in high-temperature environments. This addresses the safety hazards of insufficient flame retardancy in traditional turnover boxes. Furthermore, the substrate utilizes 50-70 parts of recycled PP mixed-color acrylic material and 5-15 parts of recycled PP paint bucket material, achieving resource recycling and reducing plastic waste pollution, thus balancing safety performance with environmental and economic needs.

[0036] 2. This invention achieves a functional breakthrough through the synergy of foldable box panels, anti-collision reinforcement devices, and socketable lids. The foldable box panels are hinged to the box base via an integrated injection-molded rotating connecting block, significantly saving storage and empty box transportation space. In use, four sets of pluggable triangular metal anti-collision reinforcement devices are tightly integrated with the pre-set grooves at the outer corners of the box panels, forming a plastic-metal composite reinforcement structure. Combined with the load-dispersing effect of the socketable lid, the load of the upper stacked layers is vertically transferred to the base along the four corners, forming a rigid load-bearing path. This can meet the batch transportation needs of heavy objects stacked up to 5 layers high. At the same time, the hand-tightened screws allow for quick assembly and disassembly without professional tools, taking into account space utilization, load-bearing capacity, and ease of operation, making it suitable for diverse logistics scenarios such as warehousing, transportation, and loading and unloading.

[0037] 3. In the flame-retardant recycled PP material of this invention, recycled PP washing machine material improves impact toughness, recycled PP multi-color cup material optimizes melt flow, and 0.2-1 parts of antioxidant (2,6-tert-butyl-4-methylphenol) and double material aging delay are added, along with 0.5-1 parts of polyethylene wax lubricant to improve processing performance. This gives the material good impact resistance and anti-aging ability, extending the service life of the turnover box, and it is also suitable for injection molding and compression molding processes. Injection molding can accurately form complex box panels with rotating connecting blocks, while compression molding improves the density of the base and box cover. There are no defects such as missing material or air bubbles during the molding process. This balance between mechanical properties and processing performance ensures the structural integrity of the product during handling and collisions, while meeting the needs of large-scale industrial production and reducing production costs and production cycle. Attached Figure Description

[0038] Figure 1 This is a perspective view of the present invention;

[0039] Figure 2 This is a schematic diagram of the base of the housing of the present invention.

[0040] The components include: 1. Box base; 2. Foldable box panel; 3. Socket-type box cover; 4. Hand-tightening screws; and 5. Anti-collision reinforcement device. Detailed Implementation

[0041] The following is in conjunction with the appendix Figure 1 -Appendix Figure 2 The present invention will be further described in detail below.

[0042] This invention provides a foldable logistics turnover box with flame-retardant properties.

[0043] A foldable logistics turnover box with flame-retardant properties, comprising:

[0044] The box base 1, the foldable box panel 2 hinged to the box base 1, the sleeve-type box cover 3, multiple hand-tightening screws 4, and four sets of anti-collision reinforcement devices 5 located at the outer corners of the foldable box panel 2. The foldable box panel 2 is made of a polymer material with preset structural rigidity and impact toughness.

[0045] The anti-collision reinforcement device 5 is made of metal and is combined with the outer corner of the foldable box panel 2 to form a plastic-metal composite reinforcement structure, which is used to resist external impacts and improve the overall stacking load-bearing capacity of the turnover box.

[0046] The anti-collision reinforcement device 5 is a pluggable triangular metal reinforcement device;

[0047] Specifically, the anti-collision reinforcement device 5 is a pluggable triangular metal reinforcement device. Due to its stable geometric characteristics, the triangular structure can evenly distribute external impact loads in three directions, avoiding structural damage caused by localized stress concentration. The pluggable design gives the turnover box flexible adaptability to various usage scenarios: when the turnover box is used to transport lightweight goods or when stacking is not required, the reinforcement device can be pulled out, reducing the overall weight of the turnover box to meet lightweight transportation needs; when transporting heavy objects or requiring multi-layer stacking, simply align the reinforcement device with the mounting position at the outer corner of the foldable box panel 2 and insert it to quickly switch to a high-load-bearing state. This convenient operation requires no special tools and is suitable for scenarios with frequent loading and unloading, such as logistics stations and warehouses.

[0048] The outer corner of the foldable box panel 2 is provided with a pre-set groove for accommodating and positioning the anti-collision reinforcement device 5;

[0049] Specifically, the outer corner of the foldable panel 2 is provided with a pre-set groove for accommodating and positioning the anti-collision reinforcement device 5. This pre-set groove is integrally formed with the foldable panel 2 through injection molding to ensure a perfect match with the shape of the anti-collision reinforcement device 5 and prevent the device from becoming loose after insertion.

[0050] The foldable box panel 2 is hinged to the box base 1 via an integrally injection-molded rotating connecting block;

[0051] Specifically, the foldable box panel 2 is hinged to the box base 1 via an integrally injection-molded rotating connecting block. The rotating connecting block is made of the same polymer material as the foldable box panel 2 and is molded synchronously with the box panel and base through an injection molding process, without any splicing gaps. Compared with traditional screw connections or hinge connections, this avoids breakage due to stress concentration at the connection points. The surface of the connecting block is also equipped with a wear-resistant coating, which can reduce wear caused by long-term folding and rotation and extend the overall service life of the turnover box.

[0052] When multiple turnover boxes are stacked, the socket-type box cover 3 transfers the load of the upper turnover box to the four sets of anti-collision reinforcement devices 5 of this box, and then the anti-collision reinforcement devices 5 transfer the load downward along the four corners of the turnover box, forming a rigid vertical load-bearing path.

[0053] Specifically, when multiple turnover boxes are stacked, the socket-type box cover 3 transfers the load of the upper turnover box to the four sets of anti-collision reinforcement devices 5 of this box. Then, the anti-collision reinforcement devices 5 transfer the load downwards along the four corners of the turnover box, forming a rigid vertical load-bearing path. When the weight of the upper turnover box is 50kg, the socket-type box cover 3 can evenly distribute the load to the four sets of anti-collision reinforcement devices 5. Each set of devices bears a load of about 12.5kg. Subsequently, the load is transferred along the anti-collision reinforcement devices 5 to the box base 1, and then from the base to the ground or the lower turnover box. This path completely avoids the weak area in the middle of the foldable box panel 2, effectively preventing the box panel from deforming and ensuring the overall structural stability without significant deformation when 5 layers are stacked.

[0054] A foldable logistics turnover box with flame-retardant properties also includes the following components by weight:

[0055] PP mixed color propylene recycled material: 50-70 parts;

[0056] PP paint bucket recycled material: 5-15 parts;

[0057] PP washing machine recycled material: 5-15 parts;

[0058] PP multi-color cup recycled material: 10-30 parts;

[0059] Composite flame retardant: 1-5 parts;

[0060] Antioxidant: 0.2-1 part;

[0061] Lubricant: 0.5-1 part;

[0062] Pigment: 0.01-0.25 parts;

[0063] The composite flame retardant is made by mixing ammonium polyphosphate, 2,3-dimethyl-2,3-diphenylbutane and flame-retardant recycled PP material in a mass ratio of 1-3:0.5-1.5:6-8.

[0064] The melt flow index of the flame-retardant recycled PP material in the composite flame retardant is 2-4 g / 10 min, and the notched impact strength is 4-8 kJ / m. 2， Specific gravity is 0.99-1.05 g / cm³ 3 ;

[0065] Specifically, the melt flow index of the flame-retardant recycled PP material in the composite flame retardant is 2-4 g / 10 min. This melt flow index range ensures good compatibility with other flame-retardant components and PP substrates, preventing agglomeration in the composite material, while also ensuring suitable flowability during processing, without affecting injection molding or compression molding; its notched impact strength is 4-8 kJ / m. 2 This material can improve the flame retardant properties of composite materials while maintaining their mechanical toughness, preventing the composite material from becoming brittle and hard due to the addition of flame retardants. This ensures that the manufactured turnover box components are not easily broken under impact, guaranteeing the reliability of the turnover box. Its specific gravity is 0.99-1.05 g / cm³. 3 Its specific gravity is close to that of other recycled PP materials, which can avoid the delamination of composite materials due to density differences and ensure uniform and stable material performance.

[0066] The antioxidant is a mixture of 2,6-tri-butyl-4-methylphenol and bis(3,5-tri-butyl-4-hydroxyphenyl) sulfide, with a mass ratio of 0.1-0.5:0.1-0.5.

[0067] Specifically, the antioxidant is a mixture of 2,6-tributyl-4-methylphenol (BHT), with a purity ≥99%, and bis(3,5-tributyl-4-hydroxyphenyl) sulfide (antioxidant 1035), with a mass ratio of 0.1-0.5:0.1-0.5. BHT is a primary phenolic antioxidant, effectively capturing active free radicals generated in the high-temperature environment of composite materials during processing such as injection molding or during use, thus delaying oxidative degradation. Antioxidant 1035 combines the functions of a primary and secondary antioxidant, not only capturing free radicals but also decomposing hydroperoxides generated during material oxidation, while possessing excellent thermal stability to protect the material's molecular chains from damage. The specific mixing ratio of the two produces a synergistic anti-aging effect, significantly extending the service life of the turnover box and preventing a decline in mechanical and flame-retardant properties due to material aging.

[0068] It also includes the following components by weight, and the following steps:

[0069] a) Provide each raw material component of any flame-retardant recycled PP material composition;

[0070] b) Mix the composite flame retardant with other raw materials except antioxidants and colorants, and granulate them once to obtain primary granules;

[0071] c) The primary granules are mixed with antioxidants and colorants, and then granulated again to obtain the final flame-retardant recycled PP material composition;

[0072] d) Using injection molding or compression molding processes, the flame-retardant recycled PP material composition obtained in step c) is used to prepare the box base 1, the foldable box panel 2, and the socketable box cover 3.

[0073] e) Install the anti-collision reinforcement device made of metal material at the outer corner of the foldable box panel 2 to form a plastic-metal composite reinforcement structure;

[0074] Specifically, provide all raw material components of any flame-retardant recycled PP material composition. All raw materials must undergo quality testing to ensure that the impurity content of the recycled PP is ≤0.3%, the ratio error of each component of the composite flame retardant is ≤±5%, and the purity of the antioxidant and lubricant meets the standards, avoiding the impact of unqualified raw materials on the performance of the final product. The composite flame retardant and other raw materials (various types of recycled PP and lubricants, excluding antioxidants and colorants) are put into a high-speed mixer and mixed for 15-20 minutes at a speed of 800-1000 r / min and a temperature of 120-130℃ to ensure uniform mixing. The mixture is then fed into a twin-screw extruder for primary granulation. The extruder temperatures are set as follows: Zone 1 160-170℃, Zone 2 175-185℃, Zone 3 180-190℃, and the die head 185-195℃, with a screw speed of 180-220 r / min. The extruded melt is then water-cooled (water temperature 25-30℃) and pelletized (particle length...). 2-3mm), to obtain primary granules. This step allows the composite flame retardant to fully integrate with the substrate, avoiding flame retardant agglomeration. The primary granules, antioxidant, and colorant are added to a high-speed mixer and mixed for 10-15 minutes at a speed of 600-800 r / min and a temperature of 80-90℃ to ensure uniform dispersion of antioxidant and colorant. The mixture is then fed into a twin-screw extruder for secondary granulation. The extruder process parameters are basically the same as those for primary granulation, except that the screw speed is slightly adjusted to 200-240 r / min. After secondary granulation, the mixture is water-cooled, pelletized, and dried (at a temperature of 70-80℃ for 1-2 hours) to obtain the final flame-retardant recycled PP material composition. This step allows for precise control of the amount of antioxidant and colorant added, while further optimizing the melt index and mechanical properties of the material. d) Using injection molding or compression molding processes, the flame-retardant recycled PP material composition obtained in step c) is used to prepare the box base, foldable box panel, and socketable box cover 3. If injection molding is used (suitable for box panels with rotating connecting blocks and outer corners of box panels with grooves), the mold temperature is set to 180-200℃, the injection pressure to 50-80MPa, the holding pressure to 40-60MPa, and the holding time to 20-30s to ensure the integrity of the component structure and the accuracy of the dimensions; if compression molding is used (suitable for bases and box lids), the mold temperature is set to 170-190℃, the pressure to 15-25MPa, and the pressing time to 30-40s to improve the density of the component; after molding, the component needs to be cooled and shaped (cooling time 25-35s), demolded, and deburred; the anti-collision reinforcement device 5 made of metal material is installed at the outer corner of the foldable box panel 2. Before installation, the pre-set groove on the outer corner of the box panel needs to be cleaned to remove dust and debris; then the reinforcement device is slowly inserted into the groove, and after insertion, the device is checked to ensure that it is stable (pull-out force ≥40N) and that there is no looseness; after installation, a plastic-metal composite reinforced structure is formed, which improves the impact resistance and load-bearing performance of the turnover box.

[0075] The flame-retardant recycled PP material in step a) is obtained through the following steps:

[0076] The composite flame retardant is mixed with other raw materials except antioxidants and colorants, and then granulated in one step to obtain primary granules.

[0077] The primary granules are mixed with antioxidants and colorants, and then granulated again to obtain flame-retardant recycled PP material.

[0078] Specifically, the first step is raw material screening and pretreatment: PP mixed-color propylene recycled materials, PP paint bucket recycled materials, PP washing machine recycled materials, and PP multi-color cup recycled materials are manually screened to remove impurities such as metals and stones. Then, they are crushed and hot-air dried (temperature 90-100℃, time 2-3 hours) to ensure the raw material moisture content is ≤0.1%. The ammonium polyphosphate and 2,3-dimethyl-2,3-diphenylbutane in the composite flame retardant are tested for fineness (fineness ≥300 mesh) to ensure they meet processing requirements. The second step is primary granulation: The pretreated PP recycled materials, composite flame retardant, and lubricant are added to a high-speed mixer according to the specified ratio and mixed for 18-22 minutes at 900-1100 r / min and 125-135℃ to ensure thorough material integration. The mixture is then fed into a twin-screw extruder. The extruder temperature in each zone is: Zone 1 165-175℃. The process involves three steps: 1) Extruding the melt at 75℃, 180-190℃ in zone two, 185-195℃ in zone three, and 190-200℃ at the die head, with a screw speed of 200-230 r / min. The resulting melt is then water-cooled and pelletized to obtain primary granules. These primary granules undergo melt index testing (ensuring a melt index of 2-4 g / 10 min). Unqualified granules require re-granulation. The third step is secondary granulation: The primary granules are mixed with antioxidants and colorants in a high-speed mixer at a speed of 700-900 r / min and a temperature of 85-95℃ for 12-18 minutes to ensure uniform dispersion of the antioxidants and colorants. The mixture is then fed into a twin-screw extruder for secondary granulation, with extrusion parameters identical to those for primary granulation. The resulting granules are dried (at 75-85℃ for 1.5-2.5 hours) and sieved (selecting granules with a particle size of 2-3 mm) to obtain flame-retardant recycled PP material.

Claims

1. A foldable logistics turnover box with flame-retardant properties, comprising: The box base (1), the foldable box panel (2) hinged to the box base (1), the sleeve-type box cover (3), multiple hand-tightening screws (4) and four sets of anti-collision reinforcement devices (5) located at the outer corners of the foldable box panel (2) are characterized in that the foldable box panel (2) is made of a polymer material with preset structural rigidity and impact toughness. The anti-collision reinforcement device (5) is made of metal material and is combined with the outer corner of the foldable box panel (2) to form a plastic-metal composite reinforcement structure to resist external impact and improve the overall stacking load-bearing capacity of the turnover box.

2. A foldable logistics turnover box with flame-retardant properties according to claim 1, characterized in that, The anti-collision reinforcement device (5) is a pluggable triangular metal reinforcement device.

3. A foldable logistics turnover box with flame-retardant properties according to claim 1, characterized in that, The outer corner of the foldable box panel (2) is provided with a preset groove for accommodating and positioning the anti-collision reinforcement device (5).

4. A foldable logistics turnover box with flame-retardant properties according to claim 1, characterized in that, The foldable box panel (2) is hinged to the box base (1) by an integrally injection-molded rotating connecting block.

5. A foldable logistics turnover box with flame-retardant properties according to claim 1, characterized in that, When multiple turnover boxes are stacked, the socket-type box cover (3) transfers the load of the upper turnover box to the four sets of anti-collision reinforcement devices (5) of this box, and then the load is transferred downward along the four corners of the turnover box through the anti-collision reinforcement devices (5), forming a rigid vertical bearing path.

6. A foldable logistics turnover box with flame-retardant properties according to claim 1, characterized in that, It also includes the following components by weight: PP mixed color propylene recycled material: 50-70 parts; PP paint bucket recycled material: 5-15 parts; PP washing machine recycled material: 5-15 parts; PP multi-color cup recycled material: 10-30 parts; Composite flame retardant: 1-5 parts; Antioxidant: 0.2-1 part; Lubricant: 0.5-1 part; Pigment: 0.01-0.25 parts; The composite flame retardant is prepared by mixing ammonium polyphosphate, 2,3-dimethyl-2,3-diphenylbutane and flame-retardant recycled PP material in a mass ratio of 1-3:0.5-1.5:6-8.

7. A foldable logistics turnover box with flame-retardant properties according to claim 6, characterized in that, The melt flow index of the flame-retardant recycled PP material in the composite flame retardant is 2-4 g / 10 min, and the notched impact strength is 4-8 kJ / m. 2 Its specific gravity is 0.99-1.05 g / cm³. 3 .

8. A foldable logistics turnover box with flame-retardant properties according to claim 6, characterized in that, The antioxidant is a mixture of 2,6-tert-butyl-4-methylphenol and bis(3,5-tert-butyl-4-hydroxyphenyl) sulfide, and the mass ratio of the two is 0.1-0.5:0.1-0.

5.

9. A foldable logistics turnover box with flame-retardant properties according to claim 1, characterized in that, It also includes the following steps: a) Provide each raw material component of any flame-retardant recycled PP material composition; b) Mix the composite flame retardant with other raw materials except antioxidants and colorants, and granulate them once to obtain primary granules; c) The primary granules are mixed with antioxidants and colorants, and then granulated again to obtain the final flame-retardant recycled PP material composition; d) Using injection molding or compression molding processes, the flame-retardant recycled PP material composition obtained in step c) is used to prepare the box base, foldable box panel and socketable box cover; e) Install a metal anti-collision reinforcement device at the outer corner of the foldable box panel to form a plastic-metal composite reinforcement structure.

10. A foldable logistics turnover box with flame-retardant properties according to claim 9, characterized in that, The flame-retardant recycled PP material in step a) is obtained through the following steps: The composite flame retardant is mixed with other raw materials except antioxidants and colorants, and then granulated once to obtain primary granules. The primary granules are mixed with antioxidants and colorants, and then subjected to secondary granulation to obtain the flame-retardant recycled PP material.

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