Macromolecule formula and production process of environment-friendly fireproof flame-retardant paper holder

Abstract

The invention relates to the related technical field of packaging paper trays, in particular to a polymer formula of an environment-friendly fireproof flame-retardant paper tray and a production process of the environment-friendly fireproof flame-retardant paper tray. 30 to 60 parts of an inorganic flame retardant; 0.5 to 3 parts of a polymer retention aid; 5 to 15 parts of bio-based reinforced fiber; 0.1 to 1 part of a pH regulator; and 200 to 500 parts of water. According to the high-molecular formula and the production process of the environment-friendly fireproof flame-retardant paper tray, a nanoscale inorganic flame retardant is synergistically compounded in plant fiber pulp to realize intrinsic flame retardance, and two-stage vacuum adsorption molding, embedded enhancement and non-adhesive hot-pressing compounding processes are combined; and a multi-layer integrated structure with the honeycomb hole anti-collision corners, the arched supporting network and the buffering protruding blocks is constructed, and finally the paper support product which is high in strength, resistant to flame, fine in buffering and degradable in the whole life cycle is obtained.

Description

Technical Field

[0001] This invention relates to the technical field of packaging paper trays, and in particular to a polymer formula and production process for an environmentally friendly, fire-retardant paper tray. Background Technology

[0002] In industrial packaging, electronic equipment, and precision instrument transportation, molded pulp products (paper trays) are gradually replacing traditional packaging materials such as foam plastics due to their environmentally friendly characteristics of renewable and biodegradable raw materials. However, when packaging flammable products (such as lithium batteries, solvent-containing chemicals, and precision circuit boards), the inherent defects of ordinary paper trays in terms of fire safety, structural strength, and cushioning performance become apparent, severely limiting their application in packaging high-value, high-risk products. Currently, to improve the flame retardancy of paper trays, common techniques involve coating or attaching flame retardant coatings or metal foils (such as aluminum foil) to their surface. While these "surface treatment" methods can provide some flame retardancy, they have significant drawbacks: First, the physical coating layer is easily worn and scratched during transportation and handling, leading to partial failure of the flame retardant function, poor fire resistance reliability, and difficulty in repair once damaged. Second, coatings or films often affect the air permeability and biodegradability of the paper tray itself, and may even introduce non-cellulose chemicals, making recycling difficult, which contradicts the initial intention of environmental protection. In terms of structural strength and cushioning, traditional paperboard trays often rely on increasing wall thickness or using pulp materials of a single density. This approach not only increases raw material consumption and product weight, but its cushioning effect is often unsatisfactory, making it difficult to effectively cope with complex impact loads from multiple angles and frequencies, and offering limited protection for delicate and fragile products. Particularly for edges and corners, the lack of effective reinforcement design makes them highly susceptible to becoming the starting point of structural failure upon impact. Furthermore, existing multi-layer composite paperboard trays generally rely on chemical adhesives for interlayer bonding. These adhesives may introduce harmful volatile organic compounds, and more importantly, their presence severely compromises the biodegradability of the paperboard material, making the supposedly environmentally friendly product difficult to dispose of after disposal, thus creating a new source of environmental pollution.

[0003] Therefore, a completely new technical solution is needed that can achieve efficient and long-lasting flame retardancy from the material itself rather than surface treatment, and improve mechanical properties through structural innovation without significantly increasing weight and cost, while ensuring that the entire manufacturing and product life cycle meets environmental protection requirements. Summary of the Invention

[0004] The purpose of this invention is to provide an environmentally friendly, fire-retardant, and flame-retardant paper tray polymer formula and production process to solve the problems of poor structural strength and poor flame-retardant effect of packaging paper trays for flammable products mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a polymer formula and production process for an environmentally friendly fire-retardant paper tray; the polymer formula for the environmentally friendly fire-retardant paper tray is composed of the following raw materials in parts by weight:

[0006] Plant fiber pulp: 50-80 parts;

[0007] Inorganic flame retardant: 30-60 parts;

[0008] Polymer retention aid: 0.5-3 parts;

[0009] Bio-based reinforcing fiber: 5-15 parts;

[0010] pH adjuster: 0.1-1 part;

[0011] Water: 200-500 servings.

[0012] Preferably, the plant fiber pulp is at least one of bamboo pulp, sugarcane pulp, and softwood pulp. The beating degree of the bamboo pulp and sugarcane pulp is controlled at 35°SR-45°SR to maintain fiber length and improve the toughness of the finished product. The beating degree of the softwood pulp is controlled at 45°SR-60°SR to increase fiber fibrillation and improve the interlacing strength and density of the pulp.

[0013] Preferably, the inorganic flame retardant is a compound of nano-sized aluminum hydroxide and magnesium hydroxide in a mass ratio of (1:1) to (3:1). The aluminum hydroxide has a particle size D50 of 1-3 μm and mainly plays an endothermic decomposition and barrier role when heated. The magnesium hydroxide has a particle size D50 of 1-5 μm and has a higher decomposition temperature, mainly playing a role in smoke suppression and carbonization promotion. The compound of the two produces a synergistic flame retardant effect.

[0014] Preferably, the polymeric retention aid is a cationic polyacrylamide with a molecular weight of 8 million to 12 million and a charge density of 10% to 30%, and the bio-based reinforcing fiber is kenaf or jute fiber with a length of 3-8 mm and a fineness of 15-25 μm.

[0015] Preferably, the pH adjuster is sodium bicarbonate or ammonia water, used to adjust the pH value of the slurry to 7.5-8.5. This weakly alkaline environment is conducive to the cationic polyacrylamide fully exerting its bridging and charge neutralization effects, thereby improving the retention rate of flame retardants and fine fibers.

[0016] A production process for environmentally friendly, fire-retardant paper trays includes the following steps:

[0017] S1. Pulp preparation and maturation: The plant fiber pulp is fully disintegrated in water in a high-speed hydraulic pulper, and then pH adjuster, inorganic flame retardant, and bio-based reinforcing fiber are added in sequence. Finally, a polymer retention aid is slowly added. The mixture is stirred at 800-1200 r / min for 15-30 minutes to obtain a uniform and stable composite pulp, which is then allowed to stand and mature for 10-20 minutes.

[0018] S2. Vacuum adsorption molding: The composite slurry obtained in S1 is transported to a vacuum adsorption molding machine with a specific mold. By controlling the vacuum degree and suction time, a flame-retardant base wet blank with anti-collision corners, honeycomb holes and surrounding groove structure is formed in sequence. The anti-collision corners are conical structures extending downwards, and the honeycomb holes in the inner ring are honeycomb grids.

[0019] S3. Embedded reinforcement: Pre-fabricated natural fiber reinforcing cloth is embedded as a reinforcement layer in the surrounding groove of the flame-retardant base wet blank;

[0020] S4. Multi-layer composite: A pre-formed basalt fiber paper support board is used as a support paperboard, and a pre-formed bamboo pulp fiberboard with protrusions and buffer protrusions is used as an inner paper tray. They are placed on the flame-retardant bottom tray wet blank with embedded reinforcement layer to form a multi-layer structure blank. The support paperboard has a partition inside, and an arched plate is distributed inside the partition.

[0021] S5. Hot pressing and drying: The multi-layered preform obtained in S4 is transferred to a hot press and hot-pressed at a temperature of 120℃-160℃ and a pressure of 2MPa-5MPa for 30-90 seconds to bond the layers together through fiber hydrogen bonds. The hot-pressed preform is then dried at 80℃-100℃ to a moisture content of 30%-40%, and then dried at 105℃-120℃ to a final moisture content of 8%-12% to obtain the finished paper tray.

[0022] Preferably, in step S2, the vacuum adsorption molding is carried out in two stages: the first stage uses a higher vacuum of -0.06MPa to -0.08MPa and suctions for 10-20 seconds to allow the slurry to quickly form the basic outline of the blank on the mold surface; the second stage uses a lower vacuum of -0.04MPa to -0.05MPa and suctions for 30-60 seconds to allow the moisture to be slowly discharged, and the fibers and flame retardants in the slurry can be rearranged and distributed to form a dense and gradient structure, so that the density of the flame retardant base after molding is greater than the density of the supporting cardboard and the inner paper tray (10).

[0023] Preferably, in step S4, the arched plates inside the supporting cardboard are evenly distributed on the inner wall of its partition, and the arched plates at the bottom of the partition are staggered according to the bottom position of the arched plates distributed on the inner wall of the partition, forming a mutually supporting mechanical network structure.

[0024] Preferably, in step S5, the hot-pressing composite process specifically involves: a hot-pressing plate applying pressure to a multi-layered structure blank; heat causing the moisture in the flame-retardant base wet blank to vaporize and penetrate to the interfaces of each layer, causing the fibers on the contact surface to soften, expand, and intertwine; after the pressure is released and the moisture evaporates, the fibers are firmly bonded together through the hydrogen bonds formed.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. Using a high-polymer composite slurry, a high proportion of nano-level inorganic flame retardants (aluminum hydroxide / magnesium) are directly and uniformly mixed into the plant fibers during the papermaking process. This "material-inherent flame retardant" method, compared to surface coating, forms a permanent flame retardant. When exposed to fire, the flame retardant rapidly undergoes an endothermic decomposition reaction, effectively reducing the ambient temperature and releasing water vapor to dilute oxygen. At the same time, it forms a dense barrier layer on the material surface, achieving highly efficient "synergistic flame retardancy," far superior to ordinary paper trays. This process releases no toxic gases, and all components are environmentally friendly, fundamentally solving the problems of traditional flame retardant performance being unsustainable, easily failing due to wear, and potentially hindering degradation.

[0027] 2. By precisely controlling the beating degree of different pulps, the flexibility and interweaving degree of the fibers are optimized. Bio-based reinforcing fibers such as kenaf fiber are added as "micro-steel bars," which greatly enhances the tear resistance of the matrix. More importantly, through a two-stage vacuum adsorption molding process, a dense bottom layer structure with anti-collision corners, honeycomb holes, and surrounding grooves is formed. Through the mechanical network of embedded reinforcement and arched plates, a high-strength support skeleton is constructed. This structure can efficiently disperse and absorb impact energy, enabling the paper tray to exhibit excellent compression resistance and cushioning performance when subjected to impact, especially corner collisions, thus providing reliable protection for the internal products that far exceeds that of traditional paper trays.

[0028] 3. This process utilizes the residual moisture in the flame-retardant base wet blank to vaporize under hot and pressure conditions, causing the fibers on each contact surface to soften, expand, and intertwine. After the pressure is released, they are firmly bonded through the strong hydrogen bonds formed. This "additive-free bonding" method not only avoids the environmental pollution and health hazards that chemical adhesives may cause, but more importantly, it enables the final product to be completely biodegradable or easily recycled after disposal, without any obstacles caused by adhesives, truly achieving a green and environmentally friendly process from production to disposal. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall process flow of the present invention. Detailed Implementation

[0030] 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.

[0031] Please see Figure 1 This invention provides a technical solution: an environmentally friendly fire-retardant paper tray polymer formula and production process. The environmentally friendly fire-retardant paper tray polymer formula is composed of the following raw materials in parts by weight:

[0032] Plant fiber pulp: 50-80 parts;

[0033] Inorganic flame retardant: 30-60 parts;

[0034] Polymer retention aid: 0.5-3 parts;

[0035] Bio-based reinforcing fiber: 5-15 parts;

[0036] pH adjuster: 0.1-1 part;

[0037] Water: 200-500 servings.

[0038] Furthermore, the plant fiber pulp is at least one of bamboo pulp, sugarcane pulp, and softwood pulp. The beating degree of bamboo pulp and sugarcane pulp is controlled at 35°SR-45°SR to maintain fiber length and improve the toughness of the finished product. The beating degree of softwood pulp is controlled at 45°SR-60°SR to increase fiber fibrillation and improve the interlacing strength and density of the pulp. In actual formulation, if high toughness is desired, bamboo pulp or sugarcane pulp with a beating degree of about 40°SR can be mainly used, as its long fibers can form a flexible network. If higher stiffness and instantaneous support strength are required, softwood pulp with a beating degree of about 55°SR can be added. Its fibrillated fibers can provide a larger bonding area, making the molded structure more compact. The pulp concentration is generally controlled between 0.8% and 1.2% to ensure good fluidity and molding effect.

[0039] Furthermore, the inorganic flame retardant is a compound of nano-sized aluminum hydroxide and magnesium hydroxide in a mass ratio of (1:1) to (3:1). The particle size D50 of aluminum hydroxide is 1-3 μm, and it mainly plays an endothermic decomposition and barrier role when heated. The particle size D50 of magnesium hydroxide is 1-5 μm, and its decomposition temperature is higher, mainly playing a role in smoke suppression and carbonization promotion. The compound of the two produces a synergistic flame retardant effect. When compounding, a mass ratio of 2:1 (aluminum hydroxide: magnesium hydroxide) is preferred. Aluminum hydroxide begins to decompose endothermally at about 220℃ (endothermic heat of about 1000 J / g), absorbing a large amount of heat and releasing water vapor; while magnesium hydroxide begins to decompose at about 340℃, with a higher endothermic heat of decomposition (about 1300 J / g), which can cover a higher temperature range and effectively inhibit smoke generation. The synergy of the two can provide continuous and efficient flame retardant protection over a wide temperature range.

[0040] Furthermore, the high-molecular retention aid is cationic polyacrylamide with a molecular weight of 8 million to 12 million and a charge density of 10% to 30%. The bio-based reinforcing fiber is kenaf or jute fiber with a length of 3-8 mm and a fineness of 15-25 μm. The addition of cationic polyacrylamide (CPAM) is a key step. Its molecular weight is preferably 10 million and its charge density is preferably 20%. When adding it, it needs to be diluted into a 0.1% to 0.3% aqueous solution first, and then slowly added to the slurry under stirring to ensure that it can be evenly dispersed and fully exert its "bridging" and "charge neutralization" effects. This captures and retains negatively charged flame retardant particles and fine fibers on the plant fibers, and the retention rate can be increased from about 40% to more than 80%. The addition of kenaf fiber is like adding steel bars to concrete, which significantly enhances the tear resistance and impact resistance of the paper core.

[0041] Furthermore, sodium bicarbonate or ammonia is used as a pH adjuster to adjust the pH of the slurry to 7.5-8.5. This slightly alkaline environment is conducive to the full bridging and charge neutralization effects of cationic polyacrylamide, improving the retention rate of flame retardants and fine fibers. The initial pH of the slurry is usually slightly acidic (about 5.5-6.5), which is not conducive to the function of cationic additives. Using sodium bicarbonate to precisely adjust the pH of the system to about 8.0 allows the CPAM molecular chains to fully extend and the positively charged groups to be more fully exposed, thereby maximizing its charge neutralization and bridging capabilities. This is a prerequisite for ensuring the efficient retention of a high proportion of flame retardants and fine fibers.

[0042] A production process for environmentally friendly, fire-retardant paper trays includes the following steps:

[0043] S1. Pulp Preparation and Maturation: The plant fiber pulp is fully disintegrated in water in a high-speed hydraulic pulper. Then, a pH adjuster, an inorganic flame retardant, and bio-based reinforcing fibers are added sequentially. Finally, a polymer retention aid is slowly added. The mixture is stirred at 800-1200 r / min for 15-30 minutes to obtain a homogeneous and stable composite pulp. The pulp is then allowed to stand for 10-20 minutes to mature. The pH adjuster should be added first to create the best working environment for the subsequent additives. Then, the flame retardant and reinforcing fibers are added to allow sufficient time for dispersion. Finally, the diluted CPAM solution is slowly added. After stirring, the mixture is allowed to stand for maturation, which allows CPAM to fully interact with various particles to form a stable flocculation system, which is beneficial for subsequent molding.

[0044] S2. Vacuum adsorption molding: The composite slurry obtained in S1 is transported to a vacuum adsorption molding machine with a specific mold. By controlling the vacuum degree and suction time, a flame-retardant base wet blank with anti-collision corners, honeycomb holes and surrounding groove structure is formed in sequence. The anti-collision corners are conical structures extending downwards, and the honeycomb holes in the inner ring are honeycomb grids.

[0045] S3. Embedded reinforcement: Pre-fabricated natural fiber reinforcement fabric is embedded as a reinforcement layer in the surrounding groove of the flame-retardant base wet blank;

[0046] S4. Multi-layer composite: A pre-formed basalt fiber paper support board is used as the support paperboard, and a pre-formed bamboo pulp fiberboard with raised and cushioning protrusions is used as the inner paper tray. These are placed sequentially on a flame-retardant bottom tray wet blank with an embedded reinforcing layer to form a multi-layer structure blank. The support paperboard has internal partitions with arched plates distributed inside. The basalt fiber paper is a high-temperature resistant, non-combustible board material that is pre-purchased or produced by wet forming. The raised and cushioning protrusions on the inner paper tray are formed in one step by vacuum adsorption using a special mold with corresponding recesses.

[0047] S5. Hot pressing and drying: The multi-layered preform obtained in S4 is transferred to a hot press and hot-pressed at a temperature of 120℃-160℃ and a pressure of 2MPa-5MPa for 30-90 seconds to bond the layers together through fiber hydrogen bonds. The hot-pressed preform is then dried at 80℃-100℃ to a moisture content of 30%-40%, and then dried at 105℃-120℃ to a final moisture content of 8%-12% to obtain the finished paper tray.

[0048] Furthermore, in step S2, the vacuum adsorption molding is performed in two stages: the first stage uses a relatively high vacuum of -0.06MPa to -0.08MPa for 10-20 seconds to allow the slurry to quickly form the basic outline of the blank on the mold surface; the second stage uses a relatively low vacuum of -0.04MPa to -0.05MPa for 30-60 seconds to allow moisture to slowly drain out, and the fibers and flame retardants in the slurry to rearrange and distribute, forming a dense and gradient structure. This results in the flame-retardant base having a higher density than the support after molding. The density of the cardboard and inner paper tray (10) is as follows: In the first stage, high vacuum rapid dehydration causes the fibers to quickly "coat" on the mold surface, forming the prototype of the blank. In this stage, the fiber and filler are relatively evenly distributed. In the second stage, low vacuum slow dehydration is used. The strong shear force is weakened, and the removal of water mainly relies on capillary action. The flame retardant particles with a larger specific gravity and the shorter fibers have more time to migrate to the mold surface (i.e. the outer layer of the paper tray) and accumulate tightly, thus naturally forming a gradient structure with a dense outer layer and a sparse inner layer. The outer layer has high density, the flame retardant is rich, and the flame retardancy and strength are both excellent.

[0049] Furthermore, in step S4, the arched plates inside the supporting cardboard are evenly distributed on the inner wall of its partition, and the arched plates at the bottom of the partition are staggered according to the bottom position of the arched plates distributed on the inner wall of the partition, forming a mutually supporting mechanical network structure. When pressure is applied to the arched plates, the force will be converted into compressive stress along the arched surface and transmitted to both ends. The staggered distribution design allows the force transmitted from the upper arched plates to be effectively borne by the lower arched plates at the staggered points, avoiding stress concentration and dispersing local pressure to the entire supporting plate, which greatly improves the compressive and bending strength.

[0050] Furthermore, in step S5, the hot-pressing composite process specifically involves: a hot-pressing plate applying pressure to the multi-layered blank; the heat vaporizing the moisture in the wet blank of the flame-retardant base and penetrating to the interfaces of each layer, causing the fibers on the contact surface to soften, expand, and intertwine. After the pressure is released and the moisture evaporates, the fibers are firmly bonded together through the hydrogen bonds formed. During hot pressing, the moisture in the wet blank is vaporized by heat, and the vapor carries heat through the interfaces of each layer, softening the amorphous regions of the cellulose fibers on the contact surface, opening the hydrogen bonds, and making the fibers flexible. Under external pressure, these soft fibers interweave, intertwine, and adhere to each other. When the pressure is released, the temperature drops, and the moisture evaporates, a large number of strong hydrogen bonds are reformed between the hydroxyl groups (-OH) of the cellulose, thereby tightly bonding the originally independent three-layer structure (flame-retardant base, support plate, and inner paper tray) into a whole. The interlayer bonding strength meets the usage requirements, and the interface is clear without any chemical additives.

[0051] Working principle: First, in the slurry preparation stage, after fully dissolving plant fibers such as bamboo pulp in water, pH adjusters, nano-grade aluminum hydroxide / magnesium compound flame retardants, kenaf reinforcing fibers, and polymer retention aids are added in a precise sequence. After high-speed stirring and static curing, a stable composite slurry with uniformly distributed functional components is formed. Subsequently, this slurry is injected into a specially designed mold through a two-stage vacuum adsorption molding process. The first stage involves high-vacuum rapid dehydration to initially form a blank outline with anti-collision corners, honeycomb holes, and surrounding grooves. The second stage involves low-vacuum slow drainage, which promotes the gradient enrichment of fibers and flame retardants in the outer layer, thereby forming a dense, flame-retardant base wet blank with efficient flame retardant retention in a single step. Then… Natural fiber reinforcing fabric is embedded in the surrounding groove of the wet blank, and prefabricated basalt fiberboard containing an interlaced arched support network and bamboo pulp fiber inner support with cushioning protrusions on the surface are stacked in sequence to form a complete "sandwich" multi-layer structure. Then, the entire blank is sent into a hot press. Under specific temperature and pressure, the moisture in the wet blank vaporizes and permeates to the interface of each layer, causing the fibers to soften, expand and intertwine. After depressurization and drying, the strong hydrogen bonds formed between the fibers achieve a strong, glue-free composite. Finally, the moisture content is precisely controlled through a segmented drying process to finalize the product and obtain an environmentally friendly paper tray that integrates high strength flame retardancy, structural support and fine cushioning from the outside to the inside, and is completely biodegradable.

[0052] 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. A polymeric formula for an environmentally friendly, fire-retardant paper tray, characterized in that: It consists of the following raw materials in parts by weight: Plant fiber pulp: 50-80 parts; Inorganic flame retardant: 30-60 parts; Polymer retention aid: 0.5-3 parts; Bio-based reinforcing fiber: 5-15 parts; pH adjuster: 0.1-1 part; Water: 200-500 servings.

2. The polymeric formula for an environmentally friendly, fire-retardant paper tray according to claim 1, characterized in that: The plant fiber pulp is at least one of bamboo pulp, sugarcane pulp, and softwood pulp. The beating degree of the bamboo pulp and sugarcane pulp is controlled at 35°SR-45°SR to maintain fiber length and improve the toughness of the finished product. The beating degree of the softwood pulp is controlled at 45°SR-60°SR to increase fiber fibrillation and improve the interlacing strength and density of the pulp.

3. The polymer formula for an environmentally friendly, fire-retardant paper tray according to claim 1, characterized in that: The inorganic flame retardant is a compound of nano-sized aluminum hydroxide and magnesium hydroxide in a mass ratio of (1:1) to (3:1). The aluminum hydroxide has a particle size D50 of 1-3 μm and is used for endothermic decomposition and blocking when heated. The magnesium hydroxide has a particle size D50 of 1-5 μm and a higher decomposition temperature, and is used for smoke suppression and carbonization promotion. The inorganic flame retardant and aluminum hydroxide are compounded for synergistic flame retardancy.

4. The polymeric formula for an environmentally friendly, fire-retardant paper tray according to claim 1, characterized in that: The polymeric retention aid is a cationic polyacrylamide with a molecular weight of 8 million to 12 million and a charge density of 10% to 30%. The bio-based reinforcing fiber is kenaf fiber with a length of 3-8 mm and a fineness of 15-25 μm.

5. The polymeric formula for an environmentally friendly, fire-retardant paper tray according to claim 1, characterized in that: The pH adjuster is sodium bicarbonate, which is used to adjust the pH value of the slurry to 7.5-8.5, so that the cationic polyacrylamide can fully exert its bridging and charge neutralization, thereby improving the retention rate of flame retardants and fine fibers.

6. A production process for an environmentally friendly fire-retardant paper tray, as described in any one of claims 1-5, using a polymeric formula for an environmentally friendly fire-retardant paper tray, characterized in that... Includes the following steps: S1. Pulp preparation and maturation: The plant fiber pulp is fully disintegrated in water in a high-speed hydraulic pulper, and then pH adjuster, inorganic flame retardant, and bio-based reinforcing fiber are added in sequence. Finally, a polymer retention aid is slowly added. The mixture is stirred at 800-1200 r / min for 15-30 minutes to obtain a uniform and stable composite pulp, which is then allowed to stand and mature for 10-20 minutes. S2. Vacuum adsorption molding: The composite slurry obtained in S1 is transported to a vacuum adsorption molding machine with a specific mold. By controlling the vacuum degree and suction time, a flame-retardant base wet blank with anti-collision corners, honeycomb holes and surrounding groove structure is formed in sequence. The anti-collision corners are conical structures extending downwards, and the honeycomb holes in the inner ring are honeycomb grids. S3. Embedded reinforcement: Pre-fabricated natural fiber reinforcing cloth is embedded as a reinforcement layer in the surrounding groove of the flame-retardant base wet blank; S4. Multi-layer composite: A pre-formed basalt fiber paper support board is used as a support paperboard, and a pre-formed bamboo pulp fiberboard with protrusions and buffer protrusions is used as an inner paper tray. They are placed on the flame-retardant bottom tray wet blank with embedded reinforcement layer to form a multi-layer structure blank. The support paperboard has a partition inside, and an arched plate is distributed inside the partition. S5. Hot pressing and drying: The multi-layered preform obtained in S4 is transferred to a hot press and hot-pressed at a temperature of 120℃-160℃ and a pressure of 2MPa-5MPa for 30-90 seconds to bond the layers together through fiber hydrogen bonds. The hot-pressed preform is then dried at 80℃-100℃ to a moisture content of 30%-40%, and then dried at 105℃-120℃ to a final moisture content of 8%-12% to obtain the finished paper tray.

7. The production process of an environmentally friendly, fire-retardant paper tray according to claim 6, characterized in that: In step S2, the vacuum adsorption molding is carried out in two stages: the first stage uses a higher vacuum of -0.06MPa to -0.08MPa and pumps for 10-20 seconds to make the slurry quickly form the basic outline of the blank on the mold surface; the second stage uses a lower vacuum of -0.04MPa to -0.05MPa and pumps for 30-60 seconds to make the water slowly drain out, and the fibers and flame retardants in the slurry are rearranged and distributed to form a dense and gradient structure, so that the density of the flame retardant base after molding is greater than the density of the supporting cardboard and the inner paper tray (10).

8. The production process of an environmentally friendly, fire-retardant paper tray according to claim 6, characterized in that: In step S4, the arched plates inside the supporting cardboard are evenly distributed on the inner wall of its partition, and the arched plates at the bottom of the partition are staggered according to the bottom position of the arched plates distributed on the inner wall of the partition, forming a mutually supporting mechanical network structure.

9. The production process of an environmentally friendly, fire-retardant paper tray according to claim 6, characterized in that: In step S5, the hot-pressing composite process specifically involves: a hot-pressing plate applying pressure to a multi-layered structure blank; heat causing the moisture in the flame-retardant base wet blank to vaporize and penetrate to the interfaces of each layer, causing the fibers on the contact surface to soften, expand, and intertwine; after the pressure is released and the moisture evaporates, the fibers are firmly bonded together through the hydrogen bonds formed.

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