Plant-based degradable foaming material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of degradable materials, and discloses a plant-based degradable foam material and a preparation method and application thereof.The plant-based degradable foam material is prepared from, by weight, 50-60 parts of plant particles, 20-25 parts of modified starch, 20-25 parts of modified polylactic acid, 8-12 parts of plasticizer, 1-2 parts of foaming agent and 1-4 parts of nucleating agent; the modified starch is acetylated distarch phosphate; the modified polylactic acid is polylactic acid grafted by hydroxyethyl methylacrylate, caprolactone acrylate and itaconic acid. The modified polylactic acid is adopted as a main raw material, the modified polylactic acid, the modified plant starch and the plant particles jointly prepare the foaming material, the compatibility of the starch and the polylactic acid can be improved, and the degradable foaming material with good elasticity and a regular foam structure is prepared; and the obtained degradable foaming material can be recycled as a chemical fertilizer slow-release carrier, so that the resource utilization rate is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of degradable materials, and in particular to a plant-based degradable foaming material and a preparation method and application thereof. Background Art

[0002] As environmental awareness continues to rise, demand for safe, biodegradable, and environmentally friendly materials is increasing across various fields. A new, safe, biodegradable foam material is needed for applications in children's toys, packaging, and thermal insulation, replacing traditional polystyrene (PS) foam. Therefore, developing a biodegradable, safe, and green foam material is of great significance.

[0003] Plant starch, derived from plants in nature, is a naturally occurring substance with abundant resources and relatively easy extraction. Using it to make toy materials produces no harmful substances during production and use, making it environmentally friendly. It is also easily biodegradable after disposal, reducing environmental pollution. Polylactic acid (PLA), with its renewable and biodegradable properties, is an ideal "green" alternative to traditional petroleum-based materials. It can be completely degraded by natural microorganisms after use. The composite foaming material produced by combining PLA with starch has garnered widespread attention and research as a green alternative to traditional PS foam. For example, patent CN105419263A discloses a method for preparing a PLA / starch composite foam material. The composite foam material comprises the following components, by weight: 5-25 parts starch, 65-85 parts PLA, 1-2 parts AC foaming agent, 0.5-1 part nucleating agent, 2-3 parts maleic anhydride, 1-2 parts initiator L-101, 0.5-1 part BPO, and 0.5-1 part titanium dioxide. However, starch and polylactic acid have poor compatibility, and directly blending them can easily lead to phase separation, reducing the mechanical properties and stability of the material. Summary of the Invention

[0004] The present invention aims to overcome the above-mentioned problems existing in the plant starch and PLA mixed foaming materials in the prior art, and provides a plant-based degradable foaming material and its preparation method and application. Modified polylactic acid is used as the main raw material to prepare the foaming material together with modified plant starch and plant particles. The compatibility of starch and polylactic acid can be improved, and a degradable foaming material with good elasticity and regular foam structure can be obtained. At the same time, the obtained degradable foaming material can be recycled and reused as a slow-release carrier for fertilizer, thereby improving resource utilization.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a plant-based biodegradable foaming material, which comprises, by weight, 50 to 60 parts of plant particles, 20 to 25 parts of modified starch, 20 to 25 parts of modified polylactic acid, 8 to 12 parts of a plasticizer, 1 to 2 parts of a foaming agent, and 1 to 4 parts of a nucleating agent; The plant particles are one or a mixture of corn particles, wheat particles, rice particles, oat particles, and coix seeds particles; The modified starch is acetylated distarch phosphate; The modified polylactic acid is polylactic acid grafted with hydroxyethyl methacrylate (HEMA), caprolactone acrylate (CLMA) and itaconic acid (IA); the mass of hydroxyethyl methacrylate, caprolactone acrylate monomer and itaconic acid monomer are 4-8%, 1-3% and 3-5% of the mass of the polylactic acid respectively.

[0006] The foaming material of the present invention is outstandingly environmentally friendly: it is prepared from biodegradable raw materials such as original plant fruit particles and modified starch. Compared with traditional polystyrene (PS) materials, it avoids the pollution problem caused by non-degradable materials, conforms to the concept of green development, and significantly improves the environmental friendliness of the material. And the raw material advantages are significant: it uses original fruit particles such as corn, which accounts for more than 50%, as the main raw materials, and completely retains the chemical nutrient structure of the grain. It not only provides the material basis for providing the nutrients needed by plants, but also gives it recycling value, which can realize the recycling of resources. At the same time, the foaming material in the present invention has multifunctional characteristics: it can be used as the main base material of children's toys and packaging products, and can be recycled after the product is discarded. As a slow-release carrier of fertilizers, it builds an "product use-recycling-reuse" industry chain, improves resource utilization, and reduces resource waste.

[0007] Preferably, the plasticizer is acetyl tributyl citrate; The nucleating agent comprises montmorillonite and talc in a mass ratio of 1:1 to 2:1; The foaming agent comprises azodicarbonamide, ZnO and sodium bicarbonate; the mass ratio of azodicarbonamide to ZnO is 20:1-2; the mass ratio of azodicarbonamide to sodium bicarbonate is 5:5-6:4.

[0008] Preferably, the particle size of the plant particles is 0.3-0.8 mm.

[0009] In a second aspect, the present invention provides a method for preparing the above-mentioned plant-based degradable foaming material, comprising the following steps: (1) Preparation of plant particles: crushing the plant fruit to obtain plant particles; (2) Preparation of modified polylactic acid: polylactic acid, hydroxyethyl methacrylate (HEMA) monomer, caprolactone acrylate (CLMA) monomer, itaconic acid (IA) monomer, initiator, and antioxidant are mixed and melt-extruded, and the mixture is cooled, pelletized, and dried to obtain modified polylactic acid; (3) The raw materials are mixed evenly and then melt-extruded to obtain the plant-based biodegradable foaming material.

[0010] Preferably, the initiator in step (2) is selected from one or more of dicumyl peroxide (DCP) and di-tert-butyl peroxide (DTBP); the antioxidant is selected from one or more of tea polyphenols, vitamin E, and tocopherol acetate; the masses of the initiator and the antioxidant are 0.5-2.0% and 0.5-1.0% of the mass of the polylactic acid, respectively.

[0011] In a third aspect, the present invention provides a plant-based composite foaming material, which comprises, in parts by weight, 100 parts of the above-mentioned plant-based degradable foaming material, 0.5 to 1.5 parts of an antioxidant, 0.5 to 1.5 parts of a flame retardant, 0.5 to 1 part of a mildew preventer, 0.5 to 1 part of a waterproofing agent, 0.1 to 3 parts of a colorant, and 0.5 to 1 part of an antistatic agent.

[0012] Preferably, the antioxidant is vitamin E; the flame retardant is aluminum hydroxide; the mildew inhibitor is sodium diacetate; the waterproofing agent is carnauba wax; the colorant is natural fruit and vegetable powder; and the antistatic agent is stearic acid monoglyceride.

[0013] In a fourth aspect, the present invention provides an application of the above-mentioned plant-based composite foam material in stuffing materials for plush dolls, children's toys, packaging products, foam cushioning coils, and thermal insulation products.

[0014] The plant-based composite foam material of this invention uses plant starch and polylactic acid (PLA) as primary raw materials. When used as the primary material in children's toys, its performance complies with China's GB6675-2014 Children's Toy Testing Standard, and is developed in accordance with the EU EN71 Children's Toy Testing Standard and the US ASTM T963 Children's Toy and CPSIA Children's Consumer Product Testing Standards. It also meets the Japan Toy Association's ST2016 standard and the relevant requirements of the JFSL Health Law. It provides reliable safety for children's growth and recreational activities, promoting their healthy development. When used as the primary material for packaging products, compared to traditional non-degradable materials such as polystyrene (PS), it avoids long-term environmental pollution after discard, reducing harm to the ecological environment and human health. This material aligns with green environmental protection concepts and has significant environmental benefits. Its quality also complies with national standards GB / T41010-2021 and GB4806.7-2023. When used as a thermal insulation product, it forms a unique porous foam structure that effectively blocks heat transfer and exhibits excellent thermal insulation properties.

[0015] Preferably, when used in children's toys, the raw materials of the children's toys include, by weight: 100 parts of the plant-based composite foam material, 10-20 parts of a plasticizer, 1-2 parts of a nucleating agent, 1-3 parts of an adhesive, 0.5-1 parts of a waterproofing agent, and 0.1-3 parts of a colorant; The plasticizer is polylactic acid grafted with polyethylene glycol and a grafting monomer, and the grafting monomer is one or more of hydroxyethyl acrylate, itaconic acid, and acrylic acid; The mass of polyethylene glycol is 15-25% of the mass of polylactic acid, and the mass of the grafted monomer is 3-8% of the mass of polylactic acid.

[0016] Preferably, when used in packaging products, the raw materials of the packaging products include, by weight: 100 parts of the plant-based composite foaming material, 2 to 5 parts of adhesive, and 0.1 to 3 parts of colorant.

[0017] Preferably, when used in a foamed cushioning coil, the foamed coil comprises BOPLA films on both sides and composite foamed particles arranged between the BOPLA films on both sides; the BOPLA films and the composite foamed particles are composited by hot pressing; and the raw materials of the composite foamed particles comprise, in parts by weight: 100 parts of the plant-based composite foaming material, 2 to 5 parts of an adhesive, and 5 to 15 parts of a toughening agent.

[0018] Preferably, when used in thermal insulation products, the thermal insulation products are thermal insulation boxes or thermal insulation panels; The raw materials of the thermal insulation box include, by weight: 100 parts of the plant-based composite foam material, 10 to 30 parts of a plasticizer, 1 to 5 parts of a nucleating agent, 2 to 5 parts of an adhesive, 0.5 to 2 parts of a plant fiber aerogel, and 1 to 3 parts of a colorant; the plasticizer is polylactic acid grafted and modified with polyethylene glycol and a grafting monomer, the grafting monomer being one or more of hydroxyethyl acrylate, itaconic acid, and acrylic acid; the mass of the polyethylene glycol is 15 to 25% of the mass of the polylactic acid, and the mass of the grafting monomer is 3 to 8% of the mass of the polylactic acid; The raw materials of the thermal insulation board include: 100 parts of the plant-based composite foaming material, 0.2-0.5 parts of antioxidant, 2-5 parts of adhesive, 1-3 parts of chitosan, 0.5-2 parts of plant fiber aerogel, and 0.5-1.5 parts of lecithin.

[0019] In a fifth aspect, the present invention provides a method for recycling the above-mentioned plant-based composite foaming material, wherein waste products containing the plant-based composite foaming material are cleaned and crushed to produce recycled materials, and the recycled materials are used as a slow-release carrier for chemical fertilizers to produce organic composite fertilizers.

[0020] Preferably, the organic compound fertilizer comprises compound fertilizer particles and a coating coated on the surface of the compound fertilizer particles; The material of the envelope is paraffin wax, and the thickness of the envelope is 0.05-0.15 mm; The raw materials of the compound fertilizer granules include, by weight, 100 parts of recycled materials, 8 to 10 parts of nitrogen fertilizer, 5 to 10 parts of phosphate fertilizer, 16 to 30 parts of potash fertilizer, 2 to 6 parts of magnesium fertilizer, 0.3 to 1 part of boron fertilizer, and 0.2 to 1 part of zinc fertilizer; the nitrogen fertilizer is urea, the phosphate fertilizer is superphosphate, the potash fertilizer is potassium sulfate, the magnesium fertilizer is magnesium sulfate, the boron fertilizer is borax, and the zinc fertilizer is zinc sulfate.

[0021] Preferably, the preparation method of the organic compound fertilizer comprises the following steps: A) mixing the raw materials of the compound fertilizer granules in proportion and then granulating them to obtain the compound fertilizer granules; B) spraying a coating material on the surface of the compound fertilizer particles and cooling the particles to obtain the organic compound fertilizer.

[0022] Therefore, the present invention has the following beneficial effects: (1) Outstanding environmental protection: The present invention uses biodegradable raw materials such as corn and modified starch to prepare plant-based biodegradable foaming materials. Compared with traditional polystyrene (PS) materials, it avoids the pollution problem caused by non-degradable materials, conforms to the concept of green development, and significantly improves the environmental protection of the materials; (2) Significant raw material advantages: Using corn and other original plant particles, which account for more than 50%, as the main raw materials, the chemical nutrient structure of grains is completely preserved, which not only provides the material basis for plants to meet their nutrient needs, but also gives them recycling value, thus realizing the recycling of resources; (3) Multifunctional properties: The plant-based biodegradable foam material of the present invention can be used as the main base material for children's toys, packaging products, insulation products, etc., and has a wide range of uses; (4) High application and recycling value: After the products made of the plant-based biodegradable foaming material in the present invention are discarded, they can be recycled as a slow-release carrier for fertilizers, thus building an industrial chain of "product use-recycling-reuse", improving resource utilization and reducing resource waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a SEM image of the plant-based degradable foaming material obtained in Example 1 of the present invention.

[0024] Figure 2 This is a SEM image of the teddy bear obtained in Application Example 2 of the present invention.

[0025] Figure 3 This is a SEM image of the thermal insulation box obtained in Application Example 6 of the present invention. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with specific embodiments.

[0027] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are all conventional methods in the art.

[0028] Overall embodiment: A plant-based biodegradable foaming material, comprising, by weight, 50-60 parts of plant particles, 20-25 parts of modified starch, 20-25 parts of modified polylactic acid, 8-12 parts of plasticizer, 1-2 parts of foaming agent, and 1-4 parts of nucleating agent; The plant particles are one or a mixture of corn particles, wheat particles, rice particles, oat particles, and coix seeds particles; The modified starch is acetylated distarch phosphate; The modified polylactic acid is polylactic acid grafted with hydroxyethyl methacrylate, caprolactone acrylate and itaconic acid; the mass of the hydroxyethyl methacrylate monomer, caprolactone acrylate monomer and itaconic acid monomer is 4-8%, 1-3% and 3-5% of the mass of the polylactic acid respectively.

[0029] As a specific embodiment, the plasticizer is acetyl tributyl citrate; the nucleating agent includes montmorillonite and talc in a mass ratio of 1:1 to 2:1; the foaming agent includes azodicarbonamide, ZnO and sodium bicarbonate; the mass ratio of azodicarbonamide to ZnO is 20:1 to 2; the mass ratio of azodicarbonamide to sodium bicarbonate is 5:5 to 6:4.

[0030] As a specific embodiment, the molecular weight of the polylactic acid is 1×10 5 ~5×10 5 .

[0031] As a specific embodiment, the particle size of the plant particles is 0.3~0.8mm.

[0032] The preparation method of the plant-based degradable foaming material comprises the following steps: (1) Preparation of plant particles: crushing the plant fruit to obtain plant particles; (2) Preparation of modified polylactic acid: polylactic acid, hydroxyethyl methacrylate monomer, caprolactone acrylate monomer, itaconic acid monomer, initiator, and antioxidant are mixed and melt-extruded, and the mixture is cooled, pelletized, and dried to obtain modified polylactic acid; (3) The raw materials are mixed evenly and then melt-extruded to obtain the plant-based biodegradable foaming material.

[0033] As a specific embodiment, the initiator described in step (2) is selected from one or more of dicumyl peroxide (DCP) and di-tert-butyl peroxide (DTBP); the antioxidant is selected from one or more of tea polyphenols, vitamin E, and tocopherol acetate; the masses of the initiator and the antioxidant are 0.5-2.0% and 0.5-1.0% of the mass of the polylactic acid, respectively.

[0034] As a specific embodiment, in step (2), melt extrusion is performed in a twin-screw extruder, and the aspect ratio of the screw is 40:1~48:1; the temperatures of different zones of the extruder are set as follows: 140~160°C for the feed section, 160~185°C for the melting section, 170~190°C for the reaction section, 170~180°C for the homogenizing section, and 150~170°C for the die section; and the rotation speed is 150~300 r / min.

[0035] As a specific implementation method, in step (3), the mixed material is conveyed to a three-stage twin-screw extruder for extrusion; the screw aspect ratio is 30:1-40:1; the temperature of the first stage is 120-140°C, the temperature of the second stage is 160-175°C, the temperature of the third stage is 170-185°C, and the die head temperature is 150-160°C; the screw speed is 100-300 r / min.

[0036] A plant-based composite foaming material comprises, in parts by weight, 100 parts of the above-mentioned plant-based degradable foaming material, 0.5-1.5 parts of an antioxidant, 0.5-1.5 parts of a flame retardant, 0.5-1 part of a mildewcide, 0.5-1 part of a waterproofing agent, 0.1-3 parts of a colorant, and 0.5-1 part of an antistatic agent.

[0037] As a specific embodiment, the antioxidant is vitamin E; the flame retardant is aluminum hydroxide; the mildew inhibitor is sodium diacetate; the waterproofing agent is carnauba wax; the colorant is natural fruit and vegetable powder; and the antistatic agent is stearic acid monoglyceride.

[0038] As a specific embodiment, the colorant is one or more of pumpkin powder, strawberry powder, carrot powder, red yeast rice powder, tomato powder, almond powder, dragon fruit powder, butterfly bean pollen, plant carbon black, spinach powder, mango powder, purple sweet potato powder, beetroot powder, matcha powder, and cocoa powder.

[0039] The invention discloses an application of the plant-based degradable foaming material in a stuffing material for a plush doll. The raw materials are mixed in proportion and then filled into a sewn plush toy shell, which is then sealed to obtain the plush doll.

[0040] As a specific implementation method, when mixing the raw materials, first place the plant-based biodegradable foaming material in a mixer and start the machine to stir; to extend the use of the product, first add an antioxidant; considering the safety of the toys, add the flame retardant after the antioxidant and continue stirring; to prevent the toys from breeding mold, add a mildew inhibitor after adding the flame retardant and stir evenly; to enhance the waterproof performance, then add Brazilian palm wax, first heat and melt it, and apply it to the particles in the form of a spray; finally, add a colorant to meet the color requirements of the toys and packaging, and stir thoroughly; add an antistatic agent after adding the colorant to reduce the accumulation of static electricity on the surface of the particles; various additives are mixed and stirred for 5 to 10 minutes, the speed is controlled at 60 to 300 r / min, and the temperature is set at 20 to 30°C; then the mixed material is placed in a blast drying oven equipment, the hot air temperature is set at 40 to 60°C, the blast speed is set at 1 to 2m / s, and the drying time is 3 to 5 hours.

[0041] As a specific implementation method, during the filling operation, if the height of a small plush toy is less than 20 cm, the filling speed is set to 6~8 L / min; if the height of a medium-sized toy is 20~50 cm, the filling speed is 8~10 L / min; if the height of a large toy is greater than 50 cm, the filling speed is 10~12 L / min; the pressure is maintained between 0.1~0.3 MPa; and the filling amount is 80~90% of the internal volume of the toy.

[0042] An application of the plant-based composite foam material in a children's toy, wherein the raw materials of the children's toy include, in parts by weight: 100 parts of the plant-based composite foam material, 10-20 parts of a plasticizer, 1-2 parts of a nucleating agent, 1-3 parts of an adhesive, 0.5-1 parts of a waterproofing agent, and 0.1-3 parts of a colorant; The plasticizer is polylactic acid grafted with polyethylene glycol and a grafting monomer, and the grafting monomer is one or more of hydroxyethyl acrylate (HEA), itaconic acid (IA), and acrylic acid (AA); The mass of polyethylene glycol is 15-25% of the mass of polylactic acid, and the mass of the grafted monomer is 3-8% of the mass of polylactic acid.

[0043] In a specific embodiment, the plasticizer is prepared by mixing polylactic acid, polyethylene glycol, a grafting monomer, a catalyst, an initiator, and an antioxidant, followed by melt extrusion, cooling, pelletizing, and drying to obtain the plasticizer. The catalyst is one or more of stannous octoate (Sn(Oct)2), tetraisopropyl titanate (TIPT), and magnesium aluminum hydrotalcites (LDHs); the initiator is one or more of dicumyl peroxide (DCP) and di-tert-butyl peroxide (DTBP); and the antioxidant is one or more of tea polyphenols, vitamin E, and tocopheryl acetate. The weights of the catalyst, initiator, and antioxidant are 0.05-1.0%, 0.1-1.0%, and 0.5-1.0%, respectively, of the weight of the polylactic acid.

[0044] As a specific embodiment, the mixing method for preparing the plasticizer is as follows: add the dried polylactic acid and polyethylene glycol to a high-speed mixer, set the speed to 100-200 r / min, and stir for 2-5 minutes; first add the antioxidant, increase the stirring speed to 300-500 r / min, and continue mixing for 5-10 minutes; then add the catalyst and continue mixing for 5-10 minutes. Then add the grafting monomer and continue stirring at the same speed for 5-10 minutes; then add the initiator, increase the speed to 500-800 r / min, and continue mixing for 10-15 minutes. The temperature is controlled at 30-45°C, and nitrogen is introduced into the mixer to prevent the material from being oxidized during the mixing process. The melt extrusion method comprises the following steps: adding the mixed materials to a twin-screw extruder for melt grafting reaction; the screw aspect ratio is 40:1-48:1; the extruder feed section temperature is 140-160°C; the melting section temperature is 160-185°C; the reaction section temperature is 170-190°C; the homogenization section temperature is 170-180°C; the die section temperature is 150-170°C; and the screw speed is 150-300 r / min. After extrusion, it is cooled in a water tank and pelletized into 3~5mm particle size; When drying, place the product in a vacuum drying oven, set the temperature at 40~60℃, the vacuum degree at -0.09 to -0.1MPa, and the drying time at 8~12h.

[0045] As a specific embodiment, the nucleating agent is montmorillonite; the adhesive is gum arabic; the waterproofing agent is carnauba wax; and the colorant is one or more of pumpkin powder, strawberry powder, carrot powder, red yeast rice powder, tomato powder, almond powder, dragon fruit powder, butterfly bean pollen, plant carbon black, spinach powder, mango powder, purple sweet potato powder, beetroot powder, matcha powder, and cocoa powder.

[0046] As a specific embodiment, when the children's toy is a large-sized lightweight toy (50-100 cm or even higher), the preparation method is as follows: 1) Preparation of plasticizer; 2) Mix the raw materials in proportion and fill them into the mold for preliminary heating and molding; 3) Supercritical carbon dioxide is filled into the mold to perform secondary foaming on the molded material; 4) The secondary foamed material is pressed into shape, and after cooling and demoulding, the children's toy is obtained.

[0047] As a specific implementation method, in step 2), the mold is first preheated to 50-60° C., and then the mixed material is filled into the mold.

[0048] As a specific implementation manner, the mold temperature during the initial heating and molding in step 2) is 80-100°C.

[0049] As a specific implementation method, in step 3), the mold temperature during secondary foaming is 100-120° C., and the pressure is controlled at 3-10 MPa; the mold is clamped by a high-clamping force hydraulic device, and then supercritical carbon dioxide is injected into the mold through a supercritical carbon dioxide injection pump injection system at an injection pressure of 5-15 MPa; a 4-12 multi-point dynamic injection method is used to inject supercritical carbon dioxide into the mold cavity, with an injection speed controlled at 2-10 g / min at each point, and a foaming time of 30-180 s.

[0050] As a specific implementation manner, the pressure during the pressing and molding in step 4) is 5-15 MPa, and the holding time is 30-180 s.

[0051] As a specific embodiment, the children's toy is a small or medium-sized lightweight toy (medium size height 20 cm to 50 cm, small size height less than 20 cm), and the preparation method is: preparing a plasticizer; then mixing the raw materials in proportion and filling them into a mold, hot-pressing the materials, cooling and demolding to obtain the children's toy.

[0052] As a specific implementation method, the mold is first preheated to 50-60° C., and then the mixed material is filled into the mold.

[0053] As a specific implementation manner, the temperature during hot pressing is 80-120° C., the pressure is 5-10 MPa, and the holding time is 10-60 s.

[0054] An application of the above-mentioned plant-based composite foaming material in a packaging product, wherein the raw materials of the packaging product include, in parts by weight: 100 parts of the plant-based composite foaming material, 2-5 parts of an adhesive, and 0-5 parts of a colorant.

[0055] As a specific embodiment, the adhesive is gum arabic, and the colorant is natural fruit and vegetable powder.

[0056] As a specific embodiment, the preparation method of the packaging product is: the raw materials are mixed in proportion and filled into a mold, the materials are hot-pressed and formed, and the packaging product is obtained after cooling and demolding.

[0057] As a specific implementation method, the mold is first preheated to 50-60° C., and then the mixed material is filled into the mold.

[0058] As a specific implementation manner, the temperature during hot pressing is 80-120° C., the pressure is 3-15 MPa, and the holding time is 10-60 s.

[0059] A use of the above-mentioned plant-based composite foam material in a foam cushioning coil, wherein the foam coil includes BOPLA films on both sides and composite foam particles arranged between the BOPLA films on both sides; the BOPLA films and the composite foam particles are composited by hot pressing; the raw materials of the composite foam particles include, by weight, 100 parts of the plant-based composite foam material, 2-5 parts of an adhesive, and 5-15 parts of a toughening agent.

[0060] As a specific implementation, the adhesive is polyvinyl alcohol (PVA), the toughening agent is acetyl tributyl citrate, the lubricant is food-grade white oil, and the antistatic agent is molecular distillation-grade monoglyceride.

[0061] As a specific embodiment, the preparation method of the foaming cushioning coil comprises the following steps: 1) uniformly mixing the raw materials to obtain composite foam particles; II) Laying down the BOPLA film; III) Evenly laying the composite foam particles on the lower BOPLA film to form a particle layer with a thickness of 6-10 mm; IV) covering the particle layer with an upper BOPLA film and heat-sealing the edges of the upper and lower BOPLA films; V) After roller hot pressing, traction and stretching, the foamed cushioning coil is rolled up.

[0062] As a specific embodiment, during hot pressing in step V), the upper roller temperature is set to 130-140°C, and the lower roller temperature is set to 125-135°C. Before hot pressing and lamination, a molecular distillation-grade monoglyceride antistatic agent, which has been prepared into a solution, is sprayed onto the surface of the upper BOPLA film. The antistatic agent forms an antistatic layer on the material surface, effectively preventing the generation of static electricity. Next, a conveyor belt transports the laid-out composite structure into the hot pressing area. The hot pressing pressure is controlled at 1-5 MPa, and the roller speed is 3-5 m / min. During the hot pressing process, food-grade white oil as a lubricant is sprayed onto the roller surface and the interface of the BOPLA film via an oil sprayer to prevent problems such as sticking and scratching. The film is then pressed into a sheet-like coil with a thickness of 2-5 mm.

[0063] As a specific implementation manner, the pulling speed during pulling and stretching is 3-6 m / min, and the stretching ratio is 1.0-1.1.

[0064] An application of the above-mentioned plant-based composite foaming material in a thermal insulation box. The raw materials of the thermal insulation box include, in parts by weight: 100 parts of the plant-based composite foaming material, 10 to 30 parts of a plasticizer, 1 to 5 parts of a nucleating agent, 2 to 5 parts of an adhesive, 0.5 to 2 parts of a plant fiber aerogel, and 1 to 3 parts of a colorant; the plasticizer is polylactic acid grafted and modified with polyethylene glycol and a grafting monomer, and the grafting monomer is one or more of hydroxyethyl acrylate, itaconic acid, and acrylic acid; the mass of the polyethylene glycol is 15 to 25% of the mass of the polylactic acid, and the mass of the grafting monomer is 3 to 8% of the mass of the polylactic acid.

[0065] As a specific implementation manner, the nucleating agent is montmorillonite; the adhesive is gum arabic; and the colorant is natural fruit and vegetable powder.

[0066] As a specific embodiment, the preparation method of the thermal insulation box includes the following steps: i) preparing a plasticizer; ii) mixing the raw materials in proportion and filling them into a mold for preliminary heating and molding; iii) filling the mold with supercritical carbon dioxide to perform secondary foaming on the molded material; iv) The secondary foamed material is pressed into shape, and after cooling and demoulding, a heat-insulating box is obtained.

[0067] As a specific implementation, in step ii), the mold is first preheated to 50-60° C., and then the mixed material is filled into the mold.

[0068] As a specific embodiment, the mold temperature during the initial heating and molding in step ii) is 80-100°C.

[0069] As a specific embodiment, in step iii), the mold temperature during secondary foaming is 100-120°C, and the pressure is controlled at 3-10 MPa; the mold is clamped by a high-clamping force hydraulic device, and then supercritical carbon dioxide is injected into the mold through a supercritical carbon dioxide injection pump injection system at an injection pressure of 5-15 MPa; a dynamic injection method is adopted at 4-12 multiple points to inject supercritical carbon dioxide into the mold cavity, with an injection speed controlled at 2-10 g / min at each point, and a foaming time of 30-180 s.

[0070] As a specific implementation manner, the pressure during the compression molding in step iv) is 5-15 MPa, and the holding time is 30-180 s.

[0071] An application of the above-mentioned plant-based composite foaming material in a thermal insulation board, wherein the raw materials of the thermal insulation board include, in parts by weight: 100 parts of the plant-based composite foaming material, 0.2-0.5 parts of an antioxidant, 2-5 parts of an adhesive, 1-3 parts of chitosan, 0.5-2 parts of a plant fiber aerogel, and 0.5-1.5 parts of lecithin.

[0072] As a specific implementation manner, the antioxidant is vitamin E, and the adhesive is polyvinyl alcohol (PVA).

[0073] As a specific embodiment, the preparation method of the thermal insulation board includes the following steps: 1) Mix the raw materials in proportion and fill them into the mold, pre-press the materials to make them soften and bond initially; 2) The pre-pressed material is hot-pressed and molded, and then cooled and demoulded to obtain a thermal insulation board.

[0074] As a specific implementation method, in step 1), the mold is first preheated to 50-60° C., and then the mixed material is filled into the mold.

[0075] As a specific implementation manner, the pre-pressing pressure in step 1) is 3-8 MPa, the temperature is 100-120° C., and the time is 3-5 min.

[0076] As a specific implementation manner, the pressure during hot pressing in step 2) is 10-25 MPa, the temperature is 140-150° C., and the holding time is 2-10 min.

[0077] A method for recycling the plant-based composite foam material comprises cleaning and crushing waste products containing the plant-based composite foam material to produce recycled material, and using the recycled material as a slow-release carrier for chemical fertilizer to produce organic composite fertilizer.

[0078] As a specific embodiment, the organic compound fertilizer includes compound fertilizer particles and a coating coated on the surface of the compound fertilizer particles; The material of the envelope is paraffin wax, and the thickness of the envelope is 0.05-0.15 mm; The raw materials of the compound fertilizer granules include, by weight, 100 parts of recycled materials, 8 to 10 parts of nitrogen fertilizer, 5 to 10 parts of phosphate fertilizer, 16 to 30 parts of potash fertilizer, 2 to 6 parts of magnesium fertilizer, 0.3 to 1 part of boron fertilizer, and 0.2 to 1 part of zinc fertilizer; the nitrogen fertilizer is urea, the phosphate fertilizer is superphosphate, the potash fertilizer is potassium sulfate, the magnesium fertilizer is magnesium sulfate, the boron fertilizer is borax, and the zinc fertilizer is zinc sulfate.

[0079] As a specific embodiment, the preparation method of the organic compound fertilizer includes the following steps: A) mixing the raw materials of the compound fertilizer granules in proportion and then granulating them to obtain the compound fertilizer granules; B) spraying a coating material on the surface of the compound fertilizer particles and cooling the particles to obtain the organic compound fertilizer.

[0080] As a specific embodiment, the granulation method in step A) is as follows: a disc granulator is used for granulation; the rotation speed is 15-20 r / min, 1-3% (concentration of 8-15 wt%) starch paste is sprayed as a binder, the granulation pressure is between 10-12 MPa, and the particle diameter is controlled to be 2-5 mm; the particles are screened by a vibrating screen to separate products with qualified particle sizes, undersized particles and powder are collected and conveyed back for re-granulation, and oversized particles are crushed and returned to the granulation process; the wet granules obtained after granulation are conveyed to a multi-layer fluidized bed dryer via a conveyor belt, and hot air at 60-80°C is used as the drying medium to rapidly dehydrate the particles in a fluidized state, controlling the moisture content to below 5 wt% to prevent agglomeration and microbial growth.

[0081] Example 1: A method for preparing a plant-based degradable foaming material, comprising the following steps: (1) Preparation of corn pellets: Grind the corn kernels into 0.3-0.8 mm pieces using a grinder, pass through a 20-50 mesh vibrating screen to prepare corn pellets, and dry with hot air at 50°C until the moisture content is ≤8%. (2) Preparation of modified polylactic acid: 1) 100 kg of PLA (NatureWorks, Model 4032D) was added to a high-speed mixer. 0.8 kg of tea polyphenols was added first, and the speed was set at 300 r / min for 5 minutes. Then, 2 kg of dicumyl peroxide (DCP) was added and stirred at the same speed for 5 minutes. 4 kg of itaconic acid, 3 kg of caprolactone acrylate, and 7.5 kg of hydroxyethyl methacrylate were mixed and stirred uniformly. The mixture was then added to the mixer, and the speed was increased to 600 r / min and mixed for 15 minutes to obtain a mixture. During mixing, the temperature in the mixer was controlled at 35°C, and nitrogen was introduced into the mixer to prevent oxidation of the materials during mixing. 2) The mixed material was added to a twin-screw extruder for melt extrusion with a screw length-diameter ratio of 40:1. The extruder temperature was set at 140°C in the feed section, 175°C in the melt section, 185°C in the reaction section, 180°C in the homogenization section, and 155°C in the die section. The screw speed was set at 200 rpm. 3) The extruded material is cooled in a water tank and then enters a pelletizer to obtain modified polylactic acid particles with a particle size of 3-5 mm; 4) Place the modified polylactic acid particles in a vacuum drying oven at 50°C and a vacuum degree of -0.1 MPa for 8 hours and set aside. The obtained modified polylactic acid was subjected to infrared spectroscopy (FT-IR) testing, and the results are shown in Table 1: Table 1: FT-IR test results of modified polylactic acid

[0082] The test results show that the unmodified PLA has an ester bond (-C=O) absorption peak at 1730-1750 cm⁻¹, but no ether bond (-COC-) absorption peak, which is consistent with the structural characteristics of PLA with ester bond as the characteristic functional group. The ester bond absorption peak of the modified polylactic acid product of the present invention shifts to 1710-1730 cm⁻¹. -1 The modification resulted in a change in the chemical environment of the ester bond; at the same time, a new 1080-1120 cm -1 The ether bond absorption peak indicates that the modification introduces a structure containing an ether bond, reflecting the effect of the modification on the chemical structure of PLA; (3) Preparation of plant-based biodegradable foaming materials: 1) 200 kg corn kernels, 100 kg acetylated distarch phosphate (Shandong Zhucheng Xingmao Corn Development Co., Ltd.), and 100 kg modified polylactic acid were mixed and stirred for 10 min. Then, 40 kg of plasticizer acetyl tributyl citrate (ATBC), 4.5 kg of montmorillonite (Zhejiang Hongxin Material Co., Ltd., brand DK7), 4.5 kg of talc (Haicheng Hetai Powder Technology Co., Ltd., brand TP-3000, 3000 mesh), 3 kg of azodicarbonamide mixed with activator ZnO (the mass ratio of azodicarbonamide to ZnO was 20:1), and 3 kg of sodium bicarbonate were added and mixed for 15 min. The speed was controlled at 600 r / min and the temperature was set at 40°C. 2) The mixed material was conveyed to a three-stage twin-screw extruder for extrusion, with a screw length-diameter ratio of 35:1; the temperature of the first stage was set at 130°C; the temperature of the second stage was 170°C; the temperature of the third stage was 180°C; the die temperature was 160°C, and the screw speed was 200 r / min; 3) The extruded material is pelletized to obtain a plant-based biodegradable foam material with a particle size of 4 to 6 mm.

[0083] The obtained plant-based biodegradable foaming material was observed by scanning electron microscope (SEM) to analyze its foaming effect. Figure 1 and as shown in Table 2.

[0084] Table 2: SEM test results of plant-based biodegradable foaming materials

[0085] From Table 2 and Figure 1 It can be seen from the results that the plant-based foam material obtained in Example 1 has a uniform pore distribution, mainly closed cells, no collapse, an interface gap width of <5 μm, a pore volume ratio of >80%, and a skeleton connection rate of >90%. At the same time, the pore density reaches 10 5 ~10 7 / cm³, average pore size 50~200μm, cell wall thickness 5~20μm, open porosity <10%, excellent overall structural performance, good foaming effect and excellent structure.

[0086] Example 2: A method for preparing a plant-based degradable foaming material, comprising the following steps: (1) Preparation of wheat granules: Grind the wheat berries into 0.3-0.8 mm pieces using a grinder, pass through a 20-50 mesh vibrating screen to prepare wheat granules, and dry with hot air at 50°C until the moisture content is ≤8%. (2) Preparation of modified polylactic acid: the method is the same as in Example 1; (3) Preparation of plant-based biodegradable foaming materials: 1) 240 kg of wheat granules, 80 kg of acetylated distarch phosphate (Shandong Zhucheng Xingmao Corn Development Co., Ltd.), and 80 kg of modified polylactic acid were mixed and stirred for 10 minutes. Then, 38 kg of plasticizer acetyl tributyl citrate (ATBC), 4.6 kg of montmorillonite (Zhejiang Hongxin Material Co., Ltd., brand DK7), 4.6 kg of talc (Haicheng Hetai Powder Technology Co., Ltd., brand TP-3000, 3000 mesh), 3.2 kg of azodicarbonamide mixed with activator ZnO (the mass ratio of azodicarbonamide to ZnO was 20:1), and 3 kg of sodium bicarbonate were added and mixed for 15 minutes. The speed was controlled at 600 r / min and the temperature was set at 40°C during mixing. 2) The mixed material is conveyed to a three-stage twin-screw extruder for extrusion, with a screw length-diameter ratio of 35:1; the first stage temperature is set at 130°C; the second stage temperature is 170°C; the third stage temperature is 180°C; the die head temperature is 160°C, and the screw speed is 190 r / min; 3) The extruded material is pelletized to obtain a plant-based biodegradable foam material with a particle size of 4 to 6 mm.

[0087] Example 3: A method for preparing a plant-based degradable foaming material, comprising the following steps: (1) Preparation of rice grains: crush the rice fruit into 0.3-0.8 mm in a grinder, pass through a 20-50 mesh vibrating screen to form rice grains, and dry with hot air at 50°C to a moisture content of ≤8%; (2) Preparation of modified polylactic acid: the method is the same as in Example 1; (3) Preparation of plant-based biodegradable foaming materials: 1) 220 kg of rice grains, 90 kg of acetylated distarch phosphate (Zhucheng Xingmao Corn Development Co., Ltd., Shandong Province), and 90 kg of modified polylactic acid were mixed and stirred for 10 min. Then, 42 kg of plasticizer acetyl tributyl citrate (ATBC), 4.5 kg of montmorillonite (Zhejiang Hongxin Material Co., Ltd., brand DK7), 4.5 kg of talc (Haicheng Hetai Powder Technology Co., Ltd., brand TP-3000, 3000 mesh), 3.1 kg of azodicarbonamide mixed with activator ZnO (the mass ratio of azodicarbonamide to ZnO was 20:1), and 2.9 kg of sodium bicarbonate were added and mixed for 15 min. The speed was controlled at 600 r / min and the temperature was set at 40°C. 2) The mixed material is conveyed to a three-stage twin-screw extruder for extrusion, with a screw length-diameter ratio of 35:1; the first stage temperature is set at 130°C; the second stage temperature is 170°C; the third stage temperature is 180°C; the die head temperature is 160°C, and the screw speed is 190 r / min; 3) The extruded material is pelletized to obtain a plant-based biodegradable foam material with a particle size of 4 to 6 mm.

[0088] Example 4: A method for preparing a plant-based degradable foaming material, comprising the following steps: (1) Preparation of plant particles: Weigh 45 kg each of corn, wheat, rice, oats, and coix seed fruit particles, mix them, grind the rice fruit into 0.3-0.8 mm particles using a grinder, pass through a 20-50 mesh vibrating sieve to prepare mixed particles, and dry them with hot air at 50°C to a moisture content of ≤8%; (2) Preparation of modified polylactic acid: the method is the same as in Example 1; (3) Preparation of plant-based biodegradable foaming materials: 1) Plant particles, 80 kg of acetylated distarch phosphate (Shandong Zhucheng Xingmao Corn Development Co., Ltd.), and 95 kg of modified polylactic acid were mixed and stirred for 10 minutes. Then, 41 kg of plasticizer acetyl tributyl citrate (ATBC), 5 kg of montmorillonite (Zhejiang Hongxin Material Co., Ltd., brand DK7), 4 kg of talc (Haicheng Hetai Powder Technology Co., Ltd., brand TP-3000, 3000 mesh), 3.2 kg of azodicarbonamide mixed with activator ZnO (the mass ratio of azodicarbonamide to ZnO was 20:1), and 2.8 kg of sodium bicarbonate were added and mixed for 15 minutes. The speed was controlled at 600 r / min and the temperature was set at 40°C during mixing. 2) The mixed material is conveyed to a three-stage twin-screw extruder for extrusion, with a screw length-diameter ratio of 35:1; the first stage temperature is set at 130°C; the second stage temperature is 170°C; the third stage temperature is 180°C; the die head temperature is 160°C, and the screw speed is 190 r / min; 3) The extruded material is pelletized to obtain a plant-based biodegradable foam material with a particle size of 4 to 6 mm.

[0089] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that azodicarbonamide and sodium bicarbonate compounded with activator ZnO are not added in step (3), and the rest are the same as in Example 1.

[0090] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that montmorillonite and talc are not added in step (3), and the rest are the same as in Example 1.

[0091] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that in step (3), azodicarbonamide compounded with activator ZnO is not added, and only sodium bicarbonate is added as the foaming agent. The rest is the same as in Example 1.

[0092] Comparative Example 4: The difference between Comparative Example 4 and Example 1 is that sodium bicarbonate is not added in step (3), and the foaming agent is only azodicarbonamide compounded with activator ZnO. The rest is the same as in Example 1.

[0093] Comparative Example 5: The difference between Comparative Example 5 and Example 1 is that no montmorillonite is added in step (3), and only talc is added as the nucleating agent. The rest is the same as in Example 1.

[0094] Comparative Example 6: The difference between Comparative Example 6 and Example 1 is that talc is not added in step (3), and only montmorillonite is added as the nucleating agent. The rest is the same as in Example 1.

[0095] Comparative Example 7: The difference between Comparative Example 7 and Example 1 is that acetylated distarch phosphate is not added in step (3), and the rest is the same as in Example 1.

[0096] Comparative Example 8: The difference between Comparative Example 8 and Example 1 is that modified polylactic acid is not added in step (3), and the rest is the same as in Example 1.

[0097] Comparative Example 9: The difference between Comparative Example 9 and Example 1 is that corn starch (Shandong Shouguang Juneng Golden Corn Development Co., Ltd., "Shengyu" brand corn starch) is used instead of acetylated distarch phosphate in step (3), and the rest is the same as in Example 1.

[0098] Comparative Example 10: The difference between Comparative Example 10 and Example 1 is that unmodified PLA is directly added in step (3), and the rest is the same as in Example 1.

[0099] With reference to GB / T 42985-2023 “Determination of biobased content in biomass-based foam materials”, the biobased content of the plant-based degradable foaming materials obtained in the above examples was tested, and the results are shown in Table 3.

[0100] Table 3: Biobased content test results

[0101] As can be seen from Table 3, the average total carbon content of the plant-based degradable foaming material prepared by the method of the present invention in the examples is between 48.15% and 48.30%, the average bio-based carbon content is between 44.86% and 45.18%, and the corresponding average bio-based content is between 93.24% and 93.87%, which fully verifies the high bio-based ratio and green environmental protection characteristics of the material obtained by the present invention.

[0102] The plant-based biodegradable foam materials obtained in the above examples and comparative examples were stirred and mixed with the adhesive, and then prepared into test samples with a size of 50×50×50 mm using a hot pressing mold. The apparent density of the samples was measured with reference to GB / T 6343-2009 "Determination of apparent density of foamed plastics and rubber". The results are shown in Table 4.

[0103] Table 4: Apparent density test results

[0104] As can be seen from Table 4, the average apparent density of the foamed materials prepared by the method of the present invention in Examples 1 to 4 is between 0.0400 and 0.0424 g / cm 3 The data are within the design limit of the product of the present invention, and the standard deviation of the data is small, and the apparent density performance of the material meets the requirements.

[0105] In Comparative Example 1, the absence of a foaming agent prevents sufficient space for gas expansion during material processing. This is because the foaming agent decomposes and releases gas when heated, forming a uniformly dispersed bubble structure that reduces the overall material density. The lack of this gas generation mechanism in Comparative Example 1 significantly reduces the material's internal porosity, leading to an increase in mass per unit volume. This ultimately results in a significantly higher apparent density than the samples in the examples.

[0106] Comparative Example 2 does not add a nucleating agent, resulting in the inability to effectively form uniform bubble nuclei during the foaming process. The nucleating agent can provide a large number of tiny heterogeneous interfaces in the material, which serve as the core site for bubble growth, promote uniform dispersion of gas and limit excessive expansion of bubbles. In the absence of a nucleating agent, the gas produced by the decomposition of the foaming agent is difficult to gather in an orderly manner, and the bubbles are prone to merging, rupture or uneven distribution, resulting in a loose pore structure and a larger pore size in the material. This uneven foaming structure increases the proportion of solid matter per unit volume of the material, which ultimately manifests as a significant increase in apparent density compared to the sample in Example 1.

[0107] Comparative Example 3 uses only sodium bicarbonate as a foaming agent, resulting in a significant decrease in the material's foaming efficiency. Azodicarbonamide (AC) is a decomposable foaming agent that decomposes to produce large amounts of gases such as nitrogen and carbon monoxide. The decomposition rate is high and the decomposition temperature is stable. Sodium bicarbonate, on the other hand, decomposes slowly and produces relatively little gas. When the two are combined, AC continuously produces gas at high temperatures, while sodium bicarbonate provides initial bubble nuclei in the early stages, creating a complementary effect that promotes the formation of a uniform and dense bubble structure. In the absence of AC, the gas produced by sodium bicarbonate alone cannot fully support material expansion, resulting in a decrease in the foaming ratio, an increase in the solid content within the material, and an increase in mass per unit volume.

[0108] When sodium bicarbonate was absent in Comparative Example 4, the initial pores formed by the initial CO2 release from sodium bicarbonate lacked a synergistic effect. Consequently, insufficient N2 was released during the high-temperature release of the AC foaming agent, resulting in no CO2 to regulate the pressure. This resulted in a small number of bubbles with uneven sizes, low porosity, and a higher mass per volume and apparent density. Furthermore, the structure became unstable, with bubbles easily merging or rupturing, further reducing porosity and increasing apparent density.

[0109] Comparative Example 5 uses only talcum powder as a nucleating agent, resulting in the inability to form an optimized bubble structure during the material foaming process. Montmorillonite is a layered silicate mineral with a large specific surface area and surface activity. It can form a large number of heterogeneous interfaces in the material, providing sufficient bubble nucleation sites. At the same time, its layered structure can limit bubble growth and prevent bubbles from over-expanding or merging. Although talcum powder has a certain nucleating ability, it lacks the layered constraint characteristics of montmorillonite. When used alone, bubbles are prone to agglomeration and rupture during growth, resulting in uneven distribution of bubble pore size and even insufficient foaming in some areas. This uneven foaming structure increases the proportion of solid matter in the unit volume of the material, resulting in a significant increase in apparent density.

[0110] Comparative Example 6 only adds montmorillonite as a nucleating agent. Both talc and montmorillonite act as nucleating agents during the foaming process. Nucleating agents can provide a large number of uniform cores for bubble formation, helping to evenly disperse the gas and form a fine pore structure. Due to the lack of the synergistic effect of talc, the number of nucleation points is reduced and the distribution uniformity is reduced. It is difficult to form a large number of fine pores during the bubble formation process, and some areas are prone to bubble merging or coarse pores. The irregularity and coarsening of the bubble structure will reduce the internal porosity of the material (reduced the proportion of bubbles per unit volume), resulting in an increase in the mass of the material for the same volume, ultimately manifesting as an apparent density higher than that of the example with talc added.

[0111] The plant-based degradable foaming materials obtained in the above examples and comparative examples were stirred and evenly mixed with the adhesive, and a hot pressing mold was used to prepare a test sample with a size of 100×100×50 mm. The compressive strength of the sample was measured with reference to GB / T 8813-2020 “Determination of Compression Properties of Rigid Foam Plastics”. The results are shown in Table 5.

[0112] Table 5: Compression strength test results

[0113] As can be seen from Table 5, the compressive strength of the foamed material prepared by the method of the present invention in the examples is 0.0309~0.0334MPa, which is better than that of the comparative example, indicating that the addition of modified starch and modified PLA can improve the compressive strength of the green composite foamed particles.

[0114] Modified starch enhances the internal connectivity of composite foam materials. It allows for better integration with the main raw materials, forming a relatively tight network structure. However, in Comparative Example 7, without the addition of modified starch, viscosity and surface tension could not be adjusted, resulting in a less uniform cell structure. When subjected to axial compressive loads, the internal structure was more susceptible to relative displacement and damage, resulting in a reduction in the compressive strength of the foam.

[0115] Modified PLA strengthens internal connectivity and acts as a support framework in composite foam materials. Comparative Example 8, which omitted modified PLA, failed to reduce interfacial tension between the raw materials, resulting in uneven mixing and unstable systems. Furthermore, the lack of a foaming support framework made it difficult to maintain a stable cell structure, resulting in a loose overall material structure that easily deformed and broke under compression, significantly reducing compressive strength.

[0116] In Comparative Example 9, acetylated distarch phosphate was replaced with ordinary corn starch. Due to the limitations of ordinary corn starch, the unmodified starch has a high number of hydroxyl groups in its molecular structure, which easily forms intermolecular hydrogen bonds and leads to aggregation. This poor interfacial compatibility with PLA and other materials makes it difficult to evenly disperse in the system. This results in decreased stability of the mixed system, an uneven cell structure, and even cell rupture. Furthermore, the connectivity of the material's internal structure is weakened, ultimately leading to reduced compressive force and strength.

[0117] Comparative Example 10 uses unmodified PLA. Due to the high interfacial tension between unmodified PLA and other raw materials, the system is unstable and cannot form a tight network structure and a stable support framework. When compressed, the internal cell structure of the material is prone to relative displacement and destruction. This results in a decrease in overall compression resistance, resulting in lower compressive force and compressive strength than the examples using modified PLA.

[0118] Example 5: A method for preparing a plant-based composite foam material, comprising the following steps: (1) First, 240 kg of the plant-based biodegradable foaming material prepared in Example 1 was placed in a mixer, and the mixer was turned on for stirring. The speed was set to 300 r / min and the temperature was 25°C. Then, 2.4 kg of antioxidant vitamin E, 1.68 kg of flame retardant aluminum hydroxide, 1.68 kg of mildew preventer sodium diacetate, 1.2 kg of waterproofing agent carnauba wax (Germany Norevo Group), 4.8 kg of colorant pumpkin powder, and 2.4 kg of antistatic agent stearic acid monoglyceride were added to the mixer in sequence and stirred for 10 minutes to obtain a mixture. (2) The mixed material is placed in a blast drying oven, the hot air temperature is set at 45°C, the blast speed is set at 1.5 m / s, and the drying time is 4 hours to obtain the plant-based composite foam material.

[0119] Example 6: A method for preparing a plant-based composite foam material, comprising the following steps: (1) First, 250 kg of the plant-based biodegradable foaming material prepared in Example 2 was placed in a mixer, and the mixer was turned on for stirring. The speed was set to 300 r / min and the temperature was 25°C. Then, 3.75 kg of antioxidant vitamin E, 2.75 kg of flame retardant aluminum hydroxide, 1.25 kg of mildew preventer sodium diacetate, 2.25 kg of waterproofing agent carnauba wax (Germany Norevo Group), 2.5 kg of colorant purple potato powder, and 1.5 kg of antistatic agent stearic acid monoglyceride were added to the mixer in sequence and stirred for 10 minutes to obtain a mixture. (2) The mixed material is placed in a blast drying oven, the hot air temperature is set at 45°C, the blast speed is set at 1.5 m / s, and the drying time is 4 hours to obtain the plant-based composite foam material.

[0120] Example 7: A method for preparing a plant-based composite foam material, comprising the following steps: (1) First, 250 kg of the plant-based biodegradable foaming material prepared in Example 3 was placed in a mixer, and the mixer was turned on for stirring. The speed was set to 300 r / min and the temperature was 25°C. Then, 3 kg of antioxidant anti-vitamin E, 2.25 kg of flame retardant aluminum hydroxide, 1.5 kg of mildew preventer sodium diacetate, 2 kg of waterproofing agent carnauba wax (Germany Norevo Group), 3 kg of colorant purple potato powder, and 1.5 kg of antistatic agent stearic acid monoglyceride were added to the mixer in sequence and stirred for 10 minutes to obtain a mixture. (2) The mixed material is placed in a blast drying oven, the hot air temperature is set at 45°C, the blast speed is set at 1.5 m / s, and the drying time is 4 hours to obtain the plant-based composite foam material.

[0121] Example 8: A method for preparing a plant-based composite foam material, comprising the following steps: (1) First, 250 kg of the plant-based biodegradable foaming material prepared in Example 4 was placed in a mixer, and the mixer was turned on for stirring. The speed was set to 300 r / min and the temperature was 25°C. Then, 3.75 kg of antioxidant vitamin E, 3 kg of flame retardant aluminum hydroxide, 2.5 kg of mildew preventer sodium diacetate, 2.5 kg of waterproofing agent carnauba wax (Germany Norevo Group), 2.5 kg of colorant purple potato powder, and 1.25 kg of antistatic agent stearic acid monoglyceride were added to the mixer in sequence and stirred for 10 minutes to obtain a mixture. (2) The mixed material is placed in a blast drying oven, the hot air temperature is set at 45°C, the blast speed is set at 1.5 m / s, and the drying time is 4 hours to obtain the plant-based composite foam material.

[0122] The flame retardant properties of the plant-based composite foam materials obtained in Examples 5 to 8 were tested with reference to GB / T 2406.2-2009 “Determination of combustion behavior of plastics by oxygen index method - Part 2: Room temperature test”. The results are shown in Table 6.

[0123] Table 6: Flame retardant performance test results

[0124] As can be seen from Table 6, the plant-based composite foam material of the present invention meets the reference value requirements in various flame retardant performance test indicators. The average limiting oxygen index is between 29% and 32%. The afterflame and smoldering time after each ignition in the vertical combustion test both meet the V-0 standard. The burning rate in the horizontal combustion test does not exceed 25 mm / min. This shows that the flame retardant (aluminum hydroxide) in this series of composite foam particle materials has a good practical flame retardant effect.

[0125] With reference to GB / T 24128-2018 “Evaluation of the Antifungal Effect of Plastic Antifungal Agents”, the antifungal properties of the plant-based composite foam materials obtained in Examples 5 to 8 were tested, and the results are shown in Table 7.

[0126] Table 7: Anti-mildew performance test results

[0127] As can be seen from Table 7, the mold growth area of ​​the plant-based composite foam material of the present invention is ≤10% for Aspergillus niger and Aspergillus flavus, reaching the Class 1 standard; the mold growth area is ≤30% for Chaetomium globosum, reaching the Class 2 standard, both meeting the mildew-proof requirements for children's toys and packaging.

[0128] With reference to GB / T 8810-2005 “Determination of water absorption of rigid foamed plastics”, the waterproof properties of the plant-based composite foam materials obtained in Examples 5 to 8 were tested. The results are shown in Table 8.

[0129] Table 8: Waterproof performance test results

[0130] As can be seen from Table 8, the average water absorption rate of the plant-based composite foam material in the present invention is ≤1% under short-term immersion conditions; under long-term immersion conditions, the average water absorption rate is ≤3%, both of which are within the reference value range of 1-5%, meeting the requirement of long-term water absorption rate ≤3% for children's toys and packaging.

[0131] With reference to GB / T 31838.2 / .3-2019 “Dielectric and resistive properties of solid insulating materials Part 2 and Part 3: Resistance properties (DC method) Surface resistivity and volume resistivity”, the antistatic properties of the plant-based composite foam materials obtained in Examples 5 to 8 were tested, and the results are shown in Table 9.

[0132] Table 9: Antistatic performance test results

[0133] It can be seen from Table 9 that the surface resistivity of the plant-based composite foam material of the present invention is 10 8 -10 9 Ω·m, all meet the requirements of 10 6 -10 11 Ω·m limit requirements; volume resistivity test value is 10 9 -10 10 Ω·m, both satisfy 10 6 -10 12 The limited standard of Ω·m can meet the application requirements of related products.

[0134] The plant-based composite foam materials obtained in Examples 5 to 8 were screened for substances of very high concern (SVHC) with reference to GB / T 39498-2020 “Guidelines for the Control of the Use of Key Chemical Substances in Consumer Products”. The results are shown in Tables 10 and 11.

[0135] Table 10: Test results of phthalates containing substances of very high concern

[0136] Table 11: Test results of PAHs SVHC

[0137] It can be seen from Tables 10 and 11 that no harmful substances such as phthalates and polycyclic aromatic hydrocarbons were detected in the plant-based composite foam material of the present invention, which meets the safety requirements for children's toys and packaging materials.

[0138] With reference to GB / T 37837-2019 "General Rules for Quadrupole Inductively Coupled Plasma Mass Spectrometry Methods", the heavy metal and specific element contents of the plant-based composite foam materials obtained in Examples 5 to 8 were tested. The limit values ​​were based on the data for toy materials. The results are shown in Table 12.

[0139] Table 12: Test results of heavy metal and specific element contents

[0140] As can be seen from Table 12, elements such as antimony, arsenic, barium, cadmium, chromium, lead, mercury, and selenium were not detected in the plant-based composite foam material of the present invention, and various indicators were far below the standard limit requirements, meeting the safety standards.

[0141] Referring to GB / T 22047-2018 “Determination of the Ultimate Aerobic Biodegradability of Plastic Materials in Soil”, the biodegradability of the plant-based composite foam materials obtained in Examples 5 to 8 was tested. The results are shown in Table 13.

[0142] Table 13: Biodegradability test results

[0143] As can be seen from Table 13, the average values ​​of the biodegradation rate test data of the plant-based composite foam material in the present invention are all ≥75%, exceeding the limit of 60%, and all meet the qualified standards.

[0144] Application Example 1: A method for preparing a plush doll, comprising the following steps: (1) Mixing raw materials: 20 kg of the plant-based composite foaming material prepared in Example 5 was placed in a low-speed mixer at a low speed of 60 r / min and stirred for 2 min; then 0.08 kg of the natural antibacterial agent lysozyme (product of Nanning Pangbo Bioengineering Co., Ltd., product number 237, enzyme activity 100,000) was added and stirred at a speed of 200 r / min for 5 min, followed by the addition of 0.04 kg of lavender plant fragrance microcapsules (product of Shanghai Hete Chemical Co., Ltd., model SNC208) and continued stirring for 5 min; (2) Preparation of the plush doll shell: Prepare the sewn 30cm long pig plush doll shell and check to ensure that it is well sewn without any damage or leaks; (3) Filling operation: Pour the mixed raw materials into the hopper of the foam particle filling machine and fill the shell of the plush doll at a filling speed of 8L / min and a pressure of 0.2MPa; the filling volume should be 85% of the internal space of the toy; (4) Sealing and post-processing: 1) Sealing: Use a needle and thread that matches the fabric of the plush doll shell and sew the filling opening tightly using the hidden needle method. The stitch spacing should be controlled at 2-3mm to ensure that the filling does not leak. 2) Shaping and slinging: Shaping the stuffed doll to make it fuller and more natural; slinging is performed as needed to adjust the doll's posture and lines to make it more beautiful.

[0145] Application Example 2: A method for preparing a large-sized lightweight children's toy, comprising the following steps: (1) Preparation of modified PLA: 1) crushing polylactic acid (NatureWorks, USA, model 4032D) into 1-2 mm particle size using a double-roll crusher; 2) Dry 200 kg of crushed PLA and 40 kg of polyethylene glycol in a vacuum oven at 50°C, -0.1 MPa, and 6 hours. 3) Add the dried polylactic acid and polyethylene glycol to a high-speed mixer, set the speed to 100 r / min, and stir for 3 minutes; first add 1.6 kg of antioxidant tea polyphenols, increase the stirring speed to 300 r / min, and continue mixing for 6 minutes; then add 0.3 kg of catalyst stannous octoate and continue mixing for 8 minutes; then add 8 kg of grafting monomer hydroxyethyl acrylate and 4 kg of itaconic acid and continue stirring at the same speed for 8 minutes; then add 0.8 kg of initiator diisopropylbenzene oxide, increase the speed to 500 r / min, and continue mixing for 10 minutes. The temperature is controlled at 35°C, and nitrogen is introduced into the mixer to prevent the materials from being oxidized during the mixing process; 4) The mixed materials were added to a twin-screw extruder for melt grafting reaction; the length-to-diameter ratio of the twin-screw extruder was 40:1; the temperature of the extruder feed section was 140°C; the temperature of the melting section was 175°C; the temperature of the reaction section was 185°C; the temperature of the homogenization section was 180°C; the temperature of the die section was 160°C; and the screw speed was 200 r / min; 5) The extruded material is cooled in a water tank and then enters a pelletizer for pelletizing. The particle size is controlled at 3-5mm. 6) Place the product in a vacuum drying oven at 50°C and a vacuum degree of -0.1 MPa for 10 h to obtain modified PLA; The obtained modified PLA was subjected to infrared spectroscopy (FT-IR) test, and the results are shown in Table 14.

[0146] Table 14: FT-IR test results of modified PLA

[0147] The results in Table 14 show that the unmodified PLA has a wavelength of 1730-1750 cm -1 There is an ester bond (-C=O) absorption peak at 1710-1730 cm-1, but no ether bond (-COC-) absorption peak, which is consistent with its structure characterized by ester bond. The ester bond absorption peak of the modified PLA of the present invention shifts to 1710-1730 cm-1. -1 , the chemical environment of the ester bond is changed due to the modification; at the same time, a new 1070-1100 cm -1 The ether bond absorption peak indicates that the modification introduces a structure containing an ether bond, reflecting the effect of the modification on the chemical structure of PLA; (2) Mixing of raw materials: 20 kg of the plant-based composite foam material prepared in Example 5 was placed in a low-speed mixer at a low speed of 60 r / min and stirred for 2 min; then 0.4 kg of gum arabic adhesive solution was slowly added, the speed was increased to 100 r / min, and the stirring time was 4 min, so that the gum arabic evenly wrapped the composite foam material particles; then 0.4 kg of nucleating agent montmorillonite (Zhejiang Fenghong New Materials Co., Ltd.) dispersed in ethanol was added, the speed was maintained at 100 r / min, and stirred for 3 min; then 0.2 kg of colorant cocoa powder was added and stirred at the same speed for 3 min; finally, 3 kg of plasticizer-modified PLA was added, the speed was increased to 200 r / min, and stirred for 5 min; (3) Molding: 1) Preheating the mold: Take out the hot molding mold of the 70cm tall teddy bear and install it on the hot molding machine. Turn on the heating function of the hot molding machine and preheat the mold temperature to 50℃. 2) Filling: Fill the preheated mold with the mixed material to 85% of the mold volume, leaving space for the subsequent injection of supercritical carbon dioxide (SC-CO2) for foaming; 3) Preliminary pre-pressing: The mold closing pressure is controlled at 7MPa and maintained for 50s to allow the raw material to be initially formed in the mold; at this time, the mold temperature is raised to 100°C, allowing the material to initially solidify under the action of pressure and temperature, forming a basic bear-shaped structure; 4) Secondary foaming: Maintaining the mold temperature at 120°C and the pressure at 6 MPa, the mold is clamped using an advanced high-clamping force hydraulic device. SC-CO2 is injected into the mold cavity simultaneously at 8 points using a dedicated SC-CO2 injection pump system at an injection pressure of 15 MPa. The injection speed is controlled at 5 g / min at each point, and the mass ratio of injected carbon dioxide to modified PLA is 0.6:1. This state is maintained for 90 seconds. 5) Thermoplastic molding: After the SC-CO2 injection and foaming are completed, the pressing program of the hot molding equipment is immediately started. The foam material in the mold is pressed at a pressure of 9 MPa and the pressure holding time is 60 seconds. The foam material is formed into the shape of a teddy bear in the mold; 6) Cooling and demoulding: After hot pressing, the mold is cooled through a circulating water channel. When the temperature drops to 55°C, the mold is opened and demoulding is carried out. The molded teddy bear is slowly pushed out of the mold using a demoulding device. (4) Post-processing: 1) Post-curing treatment: To further improve the strength and dimensional stability of the product, the demoulded teddy bear was placed in a drying oven at 50°C for post-curing treatment for 3 hours. 2) Trimming: Check the appearance of the teddy bear and use a small trimming tool to trim the flash and other defects; 3) Painting: Use water-based acrylic paint to paint the teddy bear's surface. Use white and black water-based acrylic paint to outline the eyes, dark brown lips, and pink blush on the cheeks to make the teddy bear more vivid. 4) Surface treatment and clothing: The toy is treated with a high-pressure atomization spray of non-toxic, biodegradable natural plant rice bran wax to improve its anti-fouling and antibacterial properties; then the toy is dressed to obtain the finished teddy bear.

[0148] The obtained teddy bear was observed by scanning electron microscope (SEM) to analyze its foaming effect. The results are as follows Figure 2 and as shown in Table 15.

[0149] Table 15: SEM test results of teddy bears

[0150] The results show that the teddy bear of the present invention is prepared by adding modified PLA plasticizer and carbon dioxide supercritical fluid as foaming agent, and the foaming is completed in the secondary mold cavity through the hot mold pressing process. The cell density is 10 3 ×10 4 pieces / cm 3 , average pore size 50~300μm, pore wall thickness 5~21μm, closed cell rate ≥90%, good foaming effect and good mechanical structure.

[0151] Application Example 3: A method for preparing a small-sized and lightweight children's toy, comprising the following steps: (1) Mixing raw materials: 20 kg of the plant-based composite foam material prepared in Example 5 was placed in a low-speed mixer at a low speed of 60 r / min and stirred for 2 min; then 0.6 kg of gum arabic adhesive solution was slowly added, the speed was increased to 100 r / min, and the stirring time was 4 min, so that the gum arabic evenly wrapped the composite foam material particles; then 0.4 kg of carrot powder as a colorant was added and stirred at the same speed for 3 min; (2) Molding: 1) Preheating the mold: Take out the hot molding mold of the 20×20×20cm cube building block toy and install the mold on the hot molding press. Turn on the heating function of the hot molding press and preheat the mold temperature to 50℃. 2) Filling: Fill the mixed material into the preheated mold; 3) Hot pressing: The mold temperature is set to 100°C, the pressing pressure is 6 MPa, and the holding time is 30 seconds; 4) Cooling and demoulding: After hot pressing is completed, the mold is cooled through a circulating water channel. When the temperature drops to 55°C, the mold is opened for demoulding, and the molded cube building block children's toy is slowly pushed out of the mold using a demoulding device; (3) Post-processing: 1) Post-curing treatment: In order to further improve the strength and dimensional stability of the product, the demoulded toy building blocks are placed in a drying room at a temperature of 50°C for post-curing treatment for 1 hour; 2) Trimming: Check the appearance of the toy building blocks and use small trimming tools to trim defects such as flash; 3) Painting: Painting the surface of toy blocks, using white ink to print Arabic numerals on the blocks to increase their number recognition function; 4) Surface treatment: The toys are treated with high-pressure atomization spraying of non-toxic, biodegradable natural plant rice bran wax to improve their anti-fouling and antibacterial properties, resulting in finished toy building blocks.

[0152] Comparative application example 1: The difference between Comparative Application Example 1 and Application Example 2 is that modified PLA is not added to the raw materials and supercritical carbon dioxide is not introduced for secondary foaming. The rest is the same as in Application Example 2.

[0153] Comparative application example 2: The difference between Comparative Application Example 1 and Application Example 2 is that unmodified PLA is added to the raw material as a plasticizer instead of modified PLA, and the rest is the same as in Application Example 2.

[0154] Referring to the method in ASTM D1621 / D7136 / C203, the mechanical properties of the teddy bears prepared in Example 2 and Comparative Application Examples 1 and 2 were tested. The results are shown in Table 16.

[0155] Table 16: Mechanical properties test results of teddy bears

[0156] Combined with the mechanical properties test results and process characteristics in Table 16, it can be seen that the present invention uses modified PLA plasticizer and SC-CO2 injection mold cavity secondary foaming process to manufacture large-sized lightweight children's toys, which has outstanding advantages. The modified PLA plasticizer plays a key role. The flexible group is introduced by the grafted monomer. The modified PLA is combined with the SC-CO2 secondary foaming process to improve the overall mechanical properties. The various mechanical properties of Application Example 2 are significantly better than those of the comparative application example. Its compressive strength reaches 0.43MPa and its impact strength is 15.2KJ / m 2 , flexural modulus 0.35GPa, which are higher than the comparative application example 1 without PLA and without secondary foaming (0.31MPa, 11.4KJ / m 2 , 0.24GPa) and comparative application example 2 using unmodified PLA (0.33MPa, 11.6KJ / m 2, 0.25GPa). This synergistic effect not only reduces the weight of large toys, but also significantly enhances their compressive and impact resistance and structural stability. This demonstrates that modified PLA plasticizers and the secondary foaming process can effectively improve the mechanical properties of foamed products.

[0157] With reference to GB6675-2014 "Safety of Toys", the safety of the teddy bears and toy building blocks prepared in Use Case 2 and Application Example 3 was tested.

[0158] The test results of the six phthalate plasticizer substances are shown in Tables 17 and 18.

[0159] Table 17: Test results of six phthalate substances in teddy bears in Application Example 2

[0160] Table 18: Test results of six phthalate substances in toy building blocks in application example 3

[0161] As can be seen from Tables 17 and 18, the contents of the six phthalates in the children's toy samples made from the materials of the present invention are extremely low, far below the prescribed limits, and meet the safety requirements for children's toys.

[0162] The mechanical and physical properties test results are shown in Tables 19 and 20.

[0163] Table 19: Mechanical properties test results of application example 2 teddy bear

[0164] Table 20: Mechanical properties test results of toy building blocks in Application Example 3

[0165] As can be seen from Tables 19 and 20, the children's toys prepared in the present invention did not show any unqualified conditions such as cracking, damage, or deformation in the drop tests at different heights, indicating that the products have good drop resistance and structural stability.

[0166] The flammability test results are shown in Table 21.

[0167] Table 21: Flammability test results of products in Application Examples 2 and 3

[0168] As can be seen from Table 21, the flammability test results of the children's toys prepared in the present invention are all qualified and meet the safety requirements.

[0169] The migration test results of heavy metals and specific elements are shown in Tables 22 and 23.

[0170] Table 22: Migration test results of heavy metals and specific elements in teddy bears in Application Example 2

[0171] Table 23: Migration test results of heavy metals and specific elements in toy building blocks in Application Example 3

[0172] As can be seen from Tables 22 and 23, the migratable contents of the above-mentioned heavy metals and specific elements in the children's toys of the present invention are extremely low, far below the prescribed limit standards, and meet the safety requirements for children's toys.

[0173] The biodegradability test results are shown in Tables 24 and 25.

[0174] Table 24: Experimental conditions for composting of teddy bears in Application Example 2

[0175] Table 25: Composting test results of teddy bears in Application Example 2

[0176] As can be seen from Table 25, the degradation performance of the children's toys of the present invention complies with the requirements of GB / T 41010-2021 and has good biodegradability.

[0177] Therefore, the children's toys of the present invention passed all tests in accordance with Sections 1, 2, 3, and 4 of the Children's Toy Standard GB6675-2014. This fully demonstrates that toys made with the materials of the present invention excel in safety and physical properties, meeting safety requirements for children's toys while also achieving environmental goals.

[0178] Application Example 4: A method for preparing a foam material wine bottle packaging inner liner, comprising the following steps: (1) Mixing raw materials: 20 kg of the plant-based composite foam material prepared in Example 5 was placed in a low-speed mixer at a low speed of 60 r / min and stirred for 2 min; then 0.8 kg of gum arabic adhesive solution was slowly added, and the stirring speed was set to 200 r / min for 5 min; (2) Molding: 1) Preheating the mold: Select a hot pressing mold for the inner liner of a 500mL liquor glass bottle, install the mold on a hot pressing machine, turn on the heating function of the hot pressing machine, and preheat the mold temperature to 55°C; 2) Filling and adding materials: Fill the mixed materials evenly into the preheated mold cavity; 3) Hot pressing: Start the hot pressing machine, set the mold temperature to 100°C, press at a pressure of 4 MPa, and hold the pressure for 20 seconds; 4) Cooling and demoulding: After hot pressing is completed, the heating device is turned off and the bottle is cooled through a circulating water channel. When the temperature drops to 50°C, the mold is opened and demoulding is carried out. The molded wine bottle packaging liner is pushed out of the mold using the demoulding device. (3) Post-processing: 1) Post-curing treatment: In order to further improve the strength and dimensional stability of the product, the inner liner after demoulding is placed in a drying room at a temperature of 50°C for post-curing treatment for 2 hours; 2) Trimming: Check the appearance of the packaging liner and use a small trimming tool to trim defects such as flash.

[0179] Comparative application example 3: A method for preparing a foam material wine bottle packaging inner liner, comprising the following steps: (1) Adding materials: Add the matured EPS beads (EPS beads produced by Huangyan Kangle Foam Plastic Factory, Taizhou City, Zhejiang Province) into the steam-heated mold of the inner liner of the white wine glass bottle of the same size as in Application Example 4; (2) Steam molding: Close the mold and introduce steam into the mold cavity. The steam causes the beads to further expand and fuse with each other, filling the entire cavity. Maintain the steam pressure at 0.1 MPa for 20 seconds to fully mold the product. (3) Demolding: After the molding is completed, stop the steam supply, open the mold, and use the demoulding mechanism to push the molded wine bottle packaging liner out of the mold.

[0180] (4) Post-curing treatment: In order to further improve the strength and dimensional stability of the product, the inner liner after demoulding is placed in a drying room at a temperature of 50°C for post-curing treatment for 2 hours.

[0181] Referring to GB / T 8167 “Test method for dynamic cushioning compression of cushioning materials for packaging”, the mechanical cushioning properties of the inner liners prepared in Example 4 and Comparative Application Example 3 were tested. The results are shown in Table 26.

[0182] Table 26: Inner liner cushioning compression performance test results

[0183] As shown in Table 26, the inner liner made from the plant-based composite foam material of the present invention in Application Example 4 performs better than the inner liner made from conventional EPS foam beads in Comparative Application Example 3 in terms of maximum impact force and impact force decay time. This indicates that it can withstand greater loads and absorb energy more sustainably under simulated impacts, and its cushioning effect is significantly superior to that of products made from EPS beads. This is primarily due to the advantages of the raw material composition and structural properties of the present invention, as well as the influence of the molding process.

[0184] In terms of raw material composition, the composite system of plant starch and modified PLA in the material of this invention imparts excellent elasticity and flexibility. Upon impact, plant starch exhibits a certain degree of plasticity, allowing it to absorb some of the impact energy through deformation. Modified PLA, a biodegradable thermoplastic polyester, possesses good toughness, enabling the composite foam particles to partially recover after compression deformation, repeatedly absorbing and releasing energy and prolonging the cushioning effect. EPS foam beads, on the other hand, are rigid foam materials with poor flexibility. Upon impact, they primarily absorb energy through brittle fracture, unable to provide the sustained elastic deformation cushioning provided by plant-based composite foam particles. Furthermore, the biocompatibility of the plant-based composite foam particles of this invention allows them to interact differently with each other during impact than EPS materials. During impact, hydrogen bonds and other interactions between the plant starch and PLA molecular chains continuously break and reform, dissipating significant impact energy and effectively reducing peak impact force. In contrast, the interactions between EPS molecular chains are relatively weak and monotonous, resulting in insufficient energy dissipation. Furthermore, the addition of gum arabic as an adhesive in this invention plays a key synergistic role, enhancing the material's cushioning properties. First, during the hot molding process, gum arabic tightly bonds the plant-based composite foam particles together, forming a cohesive network structure. This structure allows the particles to deform synergistically during impact, preventing relative sliding and misalignment between particles, thereby more effectively dissipating and absorbing impact force. In contrast, the EPS foam beads in Comparative Application Example 3 rely primarily on steam to expand and fuse during the molding process, resulting in relatively weak interparticle bonding. This makes them susceptible to separation or breakage during impact, reducing their cushioning performance. Second, gum arabic inherently possesses a certain degree of toughness, allowing its molecular chains to stretch and deform under external forces, thereby absorbing some of the impact energy. When gum arabic is combined with corn-based composite foam particles, a "rigid and flexible" structural system is formed. During impact, the rigid composite foam particles provide basic support strength, while the toughness of the gum arabic provides cushioning and energy absorption. The combined effects significantly enhance the material's cushioning performance. Finally, gum arabic fills the pores and interstices of the composite foam particles during the molding process, strengthening the interparticle bonding and stabilizing the material's pore structure. When subjected to impact, the stable pore structure can better play a role in gradual cushioning, preventing the pores from prematurely collapsing or damaging under the impact force, thereby ensuring that the material maintains good cushioning performance throughout the impact process. However, the pore structure of EPS foam beads is prone to collapse when subjected to a large impact force, causing its cushioning performance to decline rapidly.

[0185] In terms of molding process, the hot compression molding process used in Application Example 4 has the following advantages over the steam molding process used in Comparative Application Example 3: (1) Density control: The hot compression molding process can control the density of the product by controlling the amount of material added and the pressing pressure. In this embodiment, according to the design requirements of the inner liner, the filling amount and pressing pressure of the material can be reasonably adjusted to form a structure with a suitable density of the green composite foam material. This precise density control allows the internal pores of the material to be compressed and deformed in the best way when the material is impacted, thereby achieving the best cushioning effect. However, the steam molding process is relatively difficult to control the density of EPS foam beads, which can easily lead to uneven product density and affect the consistency of cushioning performance. (2) Internal structure: During the hot compression molding process, under the action of high temperature and high pressure, the plant-based composite foam particles and the gum arabic adhesive can be fully integrated to form a compact internal structure. This compact structure not only improves the strength of the material, but also enables the material to more effectively transmit and disperse the impact force when it is impacted, avoiding the occurrence of stress concentration. In contrast, EPS foam beads are formed through steam molding, and their internal structure is relatively low in density. When impacted, local stress concentration is prone to occur, causing material damage and reducing cushioning performance.

[0186] In accordance with GB 4806.7-2023 “National Food Safety Standard: Plastic Materials and Products for Food Contact”, the food contact safety of the inner liner in Example 4 was tested. The results are shown in Table 27.

[0187] Table 27: Food contact safety test results of the inner liner in Application Example 4

[0188] As can be seen from Table 27, the packaging products prepared in the present invention meet the safety requirements in the food contact process.

[0189] Application Example 5: A method for preparing a foamed cushioning coil comprises the following steps: (1) Preparation of composite foam particles: 1) Raw material pretreatment: The plant-based composite foam material prepared in Example 5 was crushed into particles of 0.5-2 mm in size using a blade crusher, and then dried in a forced air drying oven at 60° C. for 4 h to reduce the moisture content to below 5%; 2) Raw material mixing: 30 kg of pretreated plant-based composite foam material was placed in a low-speed mixer at 50 r / min and stirred for 2 minutes. Then, 0.9 kg of polyvinyl alcohol (PVA) was slowly added to form an adhesive solution. The stirring speed was set to 100 r / min and the stirring time was 4 minutes. Next, 1.5 kg of the toughening agent acetyl tributyl citrate (ATBC) was slowly added to the stirring mixer. The stirring speed was increased to 200 r / min and the stirring was continued for 10 minutes to obtain composite foam particles. (2) BOPLA film and composite foam particles laying: 1) Laying down the BOPLA film: Preparation: Install the BOPLA film roll (Xiamen Changsu Industrial Co., Ltd., thickness 0.05mm) on the unwinding device and adjust the unwinding tension to ensure that the film remains flat and stable during the unwinding process without wrinkles or excessive stretching. Next, for positioning and guidance, set a film guide device at the starting end of the conveyor belt to lead the BOPLA film from the roll and guide the film to accurately lay it in the center of the conveyor belt through the guide device. Next, lay the film: Start the conveyor belt and run it at a low speed while slowly releasing the BOPLA film so that it naturally lays flat on the conveyor belt. Use a roller equipped with a small number of small needles to gently press the film surface to ensure that the film fits tightly against the conveyor belt, expel air, and prevent bubbles. 2) Laying of composite foam particles: On the conveyor belt with the BOPLA film already laid, the composite foam particles are evenly spread on the film through the particle vibrating screen spreading device to form a particle layer with a thickness of 6mm; 3) Laying the upper BOPLA film: First, preparation and positioning are similar to the preparations before laying the lower film. Install another roll of BOPLA film on the unwinding device, adjust the tension and guide device, and ensure that the positions of the upper film and the lower film correspond to each other and can completely cover the composite foam particle layer; then the covering operation is carried out. When the composite foam particles are laid, start the conveyor belt at an appropriate speed to lead the upper BOPLA film from the unwinding device and slowly cover the foam particle layer. During the covering process, use tools such as a roller equipped with a small number of small needles to gently press the film from the center to both sides to ensure that the film is in close contact with the foam particles and expel any air; edge treatment: process the edge of the upper BOPLA film to align it with the edge of the lower film and seal it. Use heat sealing to ensure that the edge of the roll is neat and well sealed to prevent leakage of foam particles; (3) Hot pressing composite: 1) Roller hot pressing: The hot pressing equipment consists of two sets of heated rollers, with the upper roller temperature set at 130°C and the lower roller temperature set at 125°C. Before the composite foam particles and BOPLA film are prepared for roller hot pressing, an ethanol solution of molecular distilled monoglyceride (the mass ratio of molecular distilled monoglyceride to ethanol is 1:5) is evenly applied to one side of the upper BOPLA film by spraying. In this way, during the roller hot pressing process, the antistatic agent can form a uniform antistatic layer on the surface of the material, effectively preventing the generation of static electricity. Then, a conveyor belt transports the laid composite structure into the hot pressing area. The hot pressing pressure is controlled at 2 MPa and the roller speed is 3 m / min. During the roller hot pressing process, 0.2 kg of food-grade white oil (product of Shanghai Yizi Lubrication Technology Co., Ltd., model LUBKLEAR) is sprayed through a special oil spray device. 90NF) is evenly sprayed on the roller surface and the interface of the BOPLA film; during the hot pressing process, the foamed particles are softened by the heat and tightly bonded to the BOPLA films on the upper and lower surfaces, pressing into a sheet roll with a thickness of 2mm; 2) Traction stretching: The hot-pressed composite coil is pulled by a traction stretching machine at a speed of 3m / min, and the stretching ratio is controlled at 1:1.05; 3) Winding and Rewinding: The stretched coil enters the winding device, and then the ethanol solution of molecular distillation-grade monoglyceride is evenly attached to the other side of the sheet coil by spraying. The winding tension is controlled at 10 N to ensure that the coil is tightly and flatly wound into a large roll, completing the coil manufacturing.

[0190] Comparative application example 4: The difference between Comparative Application Example 4 and Application Example 5 is that the composite foam particles between the two layers of BOPLA film are replaced with EPS foam beads (EPS beads produced by Huangyan Kangle Foam Plastic Factory, Taizhou City, Zhejiang Province). The rest is the same as Application Example 5.

[0191] According to GB / T8167 "Dynamic Cushioning Compression Test Method for Cushioning Materials for Packaging", the mechanical cushioning properties of the foamed coils prepared in Example 5 and Comparative Application Example 4 were tested. The results are shown in Table 28.

[0192] Table 28: Test results of foam coil cushioning compression performance

[0193] It can be seen from Table 28 that the foam roll made of the plant-based composite foam material of the present invention in Application Example 5 has better cushioning effect under simulated impact than the foam roll made of the traditional EPS foam material in Comparative Application Example 4.

[0194] With reference to GB / T 1040.3-2006 “Determination of tensile properties of plastics”, the mechanical properties of the foamed membranes prepared in Example 5 and Comparative Example 4 were tested. The results are shown in Table 29.

[0195] Table 29: Test results of mechanical properties of foamed membrane

[0196] As can be seen from Table 29, the foamed coil made of the plant-based composite foaming material of the present invention in Application Example 5 is more advantageous in toughness and tear resistance than the foamed coil made of the traditional EPS foaming material in Comparative Application Example 4. The reason is that in the material of the present invention, the plant starch molecular chain contains a large number of hydroxyl groups, which can form hydrogen bonds, so that the plant starch has a certain cohesion and strength. The modified PLA is chemically modified, and the modified PLA further optimizes its compatibility with the plant starch. This composite system forms a relatively uniform microstructure inside the material, and the components work together to have better segment flexibility, thereby improving the tensile strength and elongation at break of the material. The comparative application example 4 uses EPS foam bead material, the main component of which is polystyrene. Polystyrene is a linear polymer, and the molecular chains mainly interact by van der Waals forces. The flexibility of the molecular chain is relatively poor, and its structure lacks groups that can form strong interactions with other additives, which makes the EPS material relatively weak in mechanical properties, and the tensile strength and elongation at break are not as good as the material of the present invention. At the same time, the composite structure formed by the plant starch and modified PLA in the composite foamed particles of the present invention allows the flexible segments of the plant starch to dissipate energy through molecular chain extension and slippage when subjected to external tension, while the modified PLA provides a certain degree of rigid support, enabling the material to withstand large tensile forces while deforming to a certain extent without breaking, exhibiting high buffering compression performance, tensile strength, and elongation at break. In contrast, the molecular structure of the EPS foam beads in Application Example 4 is relatively simple, and the mobility of the molecular chains is limited. During dynamic buffering compression, the EPS material's ability to absorb impact energy is relatively weak. When subjected to external forces, the molecular chains are difficult to stretch and slip to a large extent, which easily leads to stress concentration, causing the material to break under relatively low external forces, resulting in low tensile strength and elongation at break.

[0197] Referring to GB / T 7122-1996 "Determination of peel strength of high-strength adhesives", the interlayer adhesion of the foam membranes prepared in Example 5 and Comparative Example 4 was tested. The results are shown in Table 30.

[0198] Table 30: Test results of interlayer bonding strength of foam membranes

[0199] As can be seen from Table 30, the interlayer bonding strength of Application Example 5 is significantly better than that of Comparative Application Example 4, and the bonding failure form is also more conducive to maintaining structural integrity.

[0200] Referring to GB / T 1037-1988 “Test method for water vapor permeability of plastic film and sheeting – Cup method”, the moisture resistance of the foam membrane prepared in Example 5 was tested. The results are shown in Table 31.

[0201] Table 31: Test results of moisture-proof performance of foam membrane

[0202] It can be seen from Table 31 that the water vapor transmission rate of the foamed cushioning coil prepared in Application Example 5 is within the reference value of 0.1~100g / (m 2 · 24h), indicating that the foam cushioning coil of the present invention has moisture-proof performance that meets the standard requirements and can meet the moisture-proof requirements of packaging for products such as toys, electronic products, and fruits and vegetables.

[0203] Referring to GB / T 31838.2-2019 "Dielectric and resistive properties of solid insulating materials 2 Part: Resistance characteristics (DC method) Surface resistance and surface resistivity", the antistatic properties of the foam membrane prepared in Example 5 were tested, and the results are shown in Table 32.

[0204] Table 32: Antistatic performance test results of foam membrane

[0205] As can be seen from Table 32, the foamed cushioning coil prepared in the present invention has good antistatic properties.

[0206] In accordance with GB 4806.7-2023 “National Food Safety Standard: Plastic Materials and Products for Food Contact”, the food contact safety of the foamed membrane prepared in Example 5 was tested. The results are shown in Table 33.

[0207] Table 33: Food contact safety test results of the foam membrane in Application Example 5

[0208] As can be seen from Table 33, the test results of the foam coiled material in the present invention all meet the reference value requirements and satisfy the food contact safety requirements.

[0209] Application Example 6: A method for preparing a thermal insulation box, comprising the following steps: (1) Preparation of modified PLA: The method is the same as in Application Example 2; (2) Mixing of raw materials: 20 kg of the plant-based composite foam material prepared in Example 5 was placed in a low-speed mixer at a low speed of 60 r / min and stirred for 2 min; then 0.6 kg of gum arabic adhesive solution was slowly added, the speed was increased to 100 r / min, and the stirring time was 4 min; then 0.2 kg of plant fiber aerogel (a product of Anhui Keang Nano Technology Co., Ltd., model KNF-R) which is an additive for improving thermal insulation effect was added, the speed was kept at 100 r / min, and the stirring time was 3 min; then 0.4 kg of nucleating agent montmorillonite dispersed in ethanol was added, the speed was kept at 100 r / min, and the stirring time was 3 min; then 0.2 kg of colorant spinach powder was added and the stirring time was kept at the same speed for 2 min; finally 3 kg of plasticizer-modified PLA was added and the speed was increased to 200 r / min and the stirring time was 5 min; (3) Molding: 1) Preheating the mold: Use a hot pressing mold for a small-sized packaging box with a size of 23cm×18cm×14cm and a wall thickness of 2cm. Install the mold on a hot pressing machine, and press-form the box cover and box body separately. Turn on the heating function of the hot pressing machine and preheat the mold temperature to 50°C. 2) Filling: Fill the mixed material into the preheated mold, the filling amount is 80% of the mold volume; 3) Preliminary pre-pressing: The mold closing pressure is controlled at 5MPa and maintained for 30s to allow the raw material to be initially formed in the mold; at this time, the mold temperature rises to 100°C; 4) Secondary foaming: Maintaining the mold temperature at 120°C and the pressure at 4 MPa, the mold is then clamped using a high-clamping force hydraulic device. SC-CO2 is injected into the system using a dedicated injection pump at a pressure of 8 MPa. SC-CO2 is injected into the mold cavity simultaneously at four locations, with an injection speed of 3 g / min at each location. The mass ratio of injected SC-CO2 to modified PLA is 0.6:1, and this state is maintained for 45 seconds. 5) Thermoplastic molding: After the SC-CO2 injection and foaming are completed, the pressing program of the hot molding equipment is immediately started. The foam material in the mold is pressed at a pressure of 5MPa and the pressure holding time is 60s, so that the foam material is formed into the shape of the packaging box in the mold; 6) Cooling and demoulding: After the hot pressing is completed, it is cooled through a circulating water channel. When the temperature drops to 55°C, the mold is opened for demoulding, and the molded packaging foam box is slowly pushed out of the mold using the demoulding device; (4) Post-processing: 1) Post-curing treatment: In order to further improve the strength and dimensional stability of the product, the demoulded packaging box is placed in a drying room at a temperature of 45°C for post-curing treatment for 4 hours; 2) Trimming: Check the appearance of the foam box and use a small trimming tool to trim the flash and other defects; 3) Waterproof treatment: Use titanium dioxide / palm wax composite coating as waterproofing agent for surface spraying to enhance the waterproof effect.

[0210] The obtained thermal insulation box was observed by scanning electron microscope (SEM) to analyze its foaming effect. The results are as follows Figure 3 and as shown in Table 34.

[0211] Table 34: SEM test results of thermal insulation box

[0212] The results show that the thermal insulation box of the present invention is prepared by adding modified PLA plasticizer, carbon dioxide supercritical fluid as foaming agent, and the foaming is completed in the secondary mold cavity through the hot mold pressing process, and the cell density is 10 3 ~10 4 pieces / cm 3 , average pore size 50~300μm, pore wall thickness 5~20μm, closed cell rate ≥95%, good foaming effect and good mechanical structure.

[0213] Comparative application example 5: The difference between Comparative Application Example 5 and Application Example 6 is that the plant-based composite foaming material is replaced with EPS foam beads (EPS beads produced by Huangyan Kangle Foam Plastic Factory, Taizhou City, Zhejiang Province), and the rest is the same as Application Example 6.

[0214] Comparative application example 6: A method for preparing a thermal insulation box, comprising the following steps: (1) Raw material mixing: 20 kg of matured EPS foam beads (EPS beads produced by Huangyan Kangle Foam Plastic Factory, Taizhou City, Zhejiang Province) were placed in a low-speed mixer and stirred at a low speed of 60 r / min for 2 min; then 0.2 kg of plant fiber aerogel (product of Anhui Keang Nano Technology Co., Ltd., model KNF-R) as an additive to improve thermal insulation effect was added at a speed of 100 r / min and stirred for 3 min; then 0.2 kg of spinach powder as a colorant was added and stirred at the same speed for 2 min; (2) Adding materials: Add the mixed materials into a steam-heated mold of the same size as in Application Example 6; (3) Steam molding: Close the mold and introduce steam into the mold cavity. The steam causes the beads to further expand and fuse with each other, filling the entire cavity. Maintain the steam pressure at 0.15 MPa for 40 seconds to fully mold the product. (4) Demolding: After molding is completed, stop introducing steam, open the mold, and use the demoulding mechanism to push the molded EPS foam insulation box out of the mold.

[0215] (5) Post-curing treatment: In order to further improve the strength and dimensional stability of the product, the demoulding packaging box is placed in a drying room at a temperature of 50°C for post-curing treatment for 2 hours.

[0216] Referring to GB / T 8167 "Dynamic Cushioning Compression Test Method for Cushioning Materials for Packaging", the mechanical cushioning properties of the thermal insulation boxes prepared in Example 6 and Comparative Application Examples 5-6 were tested. The results are shown in Table 35.

[0217] Table 35: Test results of dynamic buffer compression performance of thermal insulation box

[0218] As can be seen in Table 35, the insulation box made with the plant-based composite foam material of the present invention in Application Example 6 outperformed the insulation boxes made with EPS foam material in Comparative Application Examples 5 and 6 in terms of maximum impact force and impact decay time. This is primarily due to the following: ① The fundamental performance advantages of the main material: The present invention uses a plant-based composite foam material as the main body, and its natural polymer structure imparts excellent toughness and strength to the product. Compared to EPS foam beads, the corn-based material inherently possesses superior elastic recovery. When impacted, it absorbs energy through molecular chain stretching and rebound, increasing the maximum impact force and extending the impact decay time. The flexible nature of its natural ingredients makes the process of reaching maximum impact force more gradual, resulting in a longer time to reach maximum impact force. ② The reinforcing effect of modified PLA: The present invention incorporates polyethylene glycol and grafts hydroxyethyl acrylate-itaconic acid-modified PLA as a plasticizer, which foams within the mold cavity to form a fine and uniform cellular structure, further enhancing the material's cushioning properties. The cross-linking of the flexible polyethylene glycol segments with hydroxyethyl acrylate-itaconic acid enables the material to undergo multiple energy dissipation mechanisms under impact, including elastic deformation of the pores, yielding and rupture of the pore walls, and other mechanisms. This significantly enhances the material's ability to absorb impact energy, increasing the maximum impact force and prolonging the decay time. Furthermore, the addition of modified PLA enables the material to reach its stress peak more slowly when subjected to stress, extending the time it takes to reach maximum impact force. ③ Adhesive Interface Strengthening: The addition of adhesives in the present invention enhances the interfacial bonding between the composite foam material particles, reduces internal weaknesses in the material, and enables the overall structure to withstand stress synergistically under impact. This strengthened interface structure effectively inhibits crack propagation, ensuring that the material does not rapidly fail under impact and increasing the maximum impact force. Furthermore, the tight particle bonding makes the material deformation process more consistent, extending the time it takes to reach maximum impact force and the duration of the impact force decay. ④ Foaming Control with Supercritical Carbon Dioxide Fluid: SC-CO2 acts as a secondary foaming agent, regulating the foaming process to form a uniform and stable foam structure. Its mild foaming conditions avoid the damage to the material structure caused by traditional foaming agents, resulting in a uniform cell wall thickness and enhanced overall strength and toughness. This uniform foam structure dissipates energy more efficiently during impact, improving the product's mechanical cushioning properties.

[0219] Referring to ASTM D3574-17 "Standard Test Methods for Flexible Porous Materials", the compression rebound properties of the thermal insulation boxes in Example 6 and Comparative Application Examples 5-6 were tested. The results are shown in Table 36.

[0220] Table 36: Compression resilience test results of thermal insulation boxes

[0221] As can be seen from the table, the thermal insulation box produced in Application Example 6 significantly outperforms the products in the comparative application examples in terms of compression and rebound performance, demonstrating superior cushioning and recovery capabilities. This is primarily due to: ① The synergistic enhancement of plant starch and modified PLA: The main raw materials in Application Example 6 utilize a composite system of plant starch and modified grafted hydroxyethyl methacrylate-caprolactone acrylate-itaconic acid-PLA. Plant starch, a renewable resource, exhibits excellent flexibility and biodegradability. Its molecular chains can form hydrogen bonds and physical entanglements with PLA, enhancing the material's toughness. Modified PLA, through grafting of hydroxyethyl methacrylate, caprolactone acrylate, and itaconic acid, introduces polar functional groups and crosslinking sites. This not only improves the compatibility of PLA with starch, but also forms a dynamic crosslinking network during compression, dispersing stress and limiting molecular chain slippage, reducing deformation. This synergistic effect enables the material to efficiently absorb energy during compression and quickly recover to its original shape during rebound. ② Structural Optimization of Foamed Particles: The protective foamed particles formed by modified grafted PLA exhibit a core-shell structure. The shell layer, grafted with monomers such as itaconic acid, enhances surface polarity, forming a more stable interface with SC-CO2 during the secondary foaming process, inhibiting cell merging and rupture. Flexible segments in the core layer (such as hydroxyethyl methacrylate) impart elastic deformation to the particles. This structural design allows the cells to gradually collapse and absorb energy during compression. During rebound, the elastic recovery force of the cell walls drives the overall structural recovery, improving the compression rebound rate. ③ The secondary foaming system, combining modified PLA with SC-CO2, offers two innovative advantages: First, the introduction of polyethylene glycol significantly enhances the flexibility of the PLA segments, enabling them to diffuse and rearrange more easily under the action of SC-CO2, resulting in a uniform and fine-grained cell structure. Second, as a green blowing agent, SC-CO2, with its low surface tension and high diffusivity, forms uniform cell cores within the material, avoiding the uneven cell size problem encountered in traditional steam foaming. At the same time, the rapid pressure relief of SC-CO2 allows cells to quickly set, reducing cell collapse and optimizing the stability and elasticity of the foam structure. ④ Synergistic Effect of Nucleating Agent and Secondary Foaming: Montmorillonite nucleating agent plays a key role in the secondary foaming process. Its nanosheet structure provides numerous nucleation sites for SC-CO2, promoting uniform foaming of the modified PLA and forming a high number of small cells. These fine cells more effectively disperse stress during compression, reducing cell rupture caused by stress concentration. During rebound, the high-density cell structure significantly improves the material's compression rebound properties through synergistic deformation and elastic recovery.

[0222] Therefore, the innovation of this invention lies not only in a single raw material or process, but also in the deep synergy between the composite foam particle formula and the secondary foaming process. The plant-based main material provides a foundation for toughness, the modified protective foam particles optimize structural strength, and the secondary foaming process regulates the cell morphology through SC-CO2 and specifically modified PLA. In addition, the gum arabic adhesive enhances the interfacial bonding strength between the foam particles, reducing the relative slippage and separation between particles during compression. This allows the material to deform synergistically as a whole and transfer energy evenly when subjected to force. During rebound, the particles can recover synchronously, further reducing deformation, thereby synergistically improving the compression rebound rate. Ultimately, a significant improvement in the compression rebound rate is achieved, surpassing the performance level of traditional EPS materials.

[0223] With reference to GB / T 10294-2008 “Determination of steady-state thermal resistance and related properties of insulating materials – Guarded hot plate method”, the thermal insulation performance of the insulating boxes in Example 6 and Comparative Application Examples 5-6 was tested, and the results are shown in Table 37.

[0224] Table 37: Thermal insulation performance test results of thermal insulation boxes

[0225] The thermal insulation performance is superior, better meeting the need for efficient insulation. The main reasons are: 1. Differences in the main raw material properties: Application Example 6 uses a corn-based composite foam material as the main component. Compared to the EPS beads in Comparative Application Examples 5 and 6, the plant-based material inherently has a denser molecular structure and lower thermal conductivity. The orderly molecular chains of the natural plant-based component effectively hinder heat transfer, while the EPS beads are made of polystyrene, with larger interstitial gaps between the molecular chains, allowing heat to easily dissipate through heat transfer. As shown in the table, the thermal insulation box in Application Example 6 exhibits significantly greater thermal conductivity than the thermal insulation box in the Comparative Application Example. 2. Synergistic Effects of Additives: First, the modified PLA plasticizer added to Application Example 6 undergoes secondary foaming within the mold cavity, forming an interpenetrating network structure that fills the cell gaps and reduces heat dissipation through air convection. While Comparative Application Example 5 uses the same modified PLA, the main EPS beads have poor compatibility with the modified PLA, preventing them from fully utilizing their structural optimization benefits. Comparative Application Example 6 even uses no additives, resulting in even lower structural stability. Secondly, the plant fiber aerogel added to Application Example 6 provides highly effective insulation. While aerogel was also added to the two comparative application examples, its dispersion was limited by the high thermal conductivity of the EPS main material. In Application Example 6, the strong interfacial bonding between the plant-based material and the aerogel allowed the aerogel to be evenly dispersed within the matrix, forming a continuous, low-thermal conductivity network. This maximized its ultra-low thermal conductivity (the thermal conductivity coefficient can be as low as 0.03 W / (m·K)) and significantly reduced the overall thermal conductivity. (3) Adhesive Enhances Integrity: In Application Example 6, the gum arabic adhesive strengthened the bonding between the plant-based composite foam material particles, forming a tight overall structure and reducing gaps and thermal bridges within the material. In Comparative Application Example 5, the bonding between the EPS beads and the gum arabic was weak. Comparative Application Example 6, which lacked adhesive, resulted in numerous voids within the material, allowing heat to easily conduct through these defects, reducing thermal insulation performance.

[0226] In accordance with GB 4806.7-2023 “National Food Safety Standard: Plastic Materials and Products for Food Contact”, the food contact safety of the thermal insulation box prepared in Example 6 was tested. The results are shown in Table 38.

[0227] Table 38: Food contact safety test results of the thermal insulation box in Application Example 6

[0228] As can be seen from Table 38, the test results of the thermal insulation box in the present invention all meet the reference value requirements and meet the food contact safety requirements.

[0229] Application Example 7: A method for preparing a thermal insulation board comprises the following steps: (1) Mixing of raw materials: 20 kg of the plant-based composite foaming material prepared in Example 5 and 0.06 kg of antioxidant vitamin E were placed in a low-speed mixer, followed by the addition of 0.6 kg of polyvinyl alcohol (PVA) to form an adhesive solution, with the stirring speed set at 100 r / min and the stirring time at 5 min; then 0.2 kg of lecithin (a product of Archer Daniels Midland, USA) was added, the stirring speed was maintained at 100 r / min, and the stirring time was 10 min; then 0.2 kg of chitosan (a product of Zhejiang Jinke Pharmaceutical Co., Ltd., food-grade chitosan with a deacetylation degree of 90%) was added, the stirring speed was increased to 200 r / min, and the stirring time was 10 min; finally, 0.2 kg of plant fiber aerogel (a product of Anhui Keang Nanotechnology Co., Ltd., model KNF-R) was added; the stirring speed was switched to a low speed of 100 r / min and the stirring time was 10 min; (2) Molding: 1) Preheating the mold: Customize the hot pressing mold according to the size of the foam board 122cm×61cm×3cm, using high-strength steel. Evenly spray the mold release agent before each use to ensure smooth demolding. Install the required mold on the hot pressing machine, turn on the heating function of the hot pressing machine, and preheat the mold temperature to 55°C. 2) Filling and adding materials: Fill the mixed materials evenly into the preheated mold cavity; 3) Pre-pressing stage: Set the pressure to 5 MPa and the temperature to 110°C for 3 minutes to allow the material to initially soften and bond; 4) Main pressure stage: Rapidly increase the pressure to 10MPa and the temperature to 140℃. The holding time is adjusted according to the thickness of the board. For a 3cm thick board, the holding time is 3 minutes. Under high temperature and high pressure, the materials are further melted and fused to form a compact foam board structure. 5) Cooling and demolding: Maintaining constant pressure, cool the mold by passing water through the cooling pipes inside the mold to reduce the temperature to below 70°C. Maintain stable pressure during the cooling process to prevent deformation of the sheet. After cooling is complete, slowly reduce the hot press pressure to 0 MPa, open the mold, and carefully remove the formed foam sheet. (3) Post-processing: 1) Trimming: Use a trimming machine to precisely trim the foam board, remove excess edges, ensure accurate dimensions, and ensure that the length and width of the foam board meet the required standard specifications; 2) Annealing: Transfer the foam board to a constant temperature drying room for constant temperature post-treatment. For foam boards used for temporary building insulation, the temperature is set at 50°C and constant temperature treatment is carried out for 5 hours. This constant temperature post-treatment eliminates the internal stress of the foam board after hot pressing, improves the cellular structure, and enhances the dimensional stability, physical properties, and chemical stability of the foam board. 3) Waterproof treatment: Use titanium dioxide / palm wax composite coating as waterproofing agent for surface spraying to enhance the waterproof effect.

[0230] Comparative application example 7: The difference between Comparative Application Example 7 and Application Example 7 is that the plant-based composite foaming material is replaced with EPS foam beads (EPS beads produced by Huangyan Kangle Foam Plastic Factory, Taizhou City, Zhejiang Province), and the rest is the same as Application Example 7.

[0231] Comparative application example 8: A method for preparing a thermal insulation board comprises the following steps: (1) Mixing of raw materials: 20 kg of EPS foam beads (EPS beads produced by Huangyan Kangle Foam Plastic Factory, Taizhou City, Zhejiang Province) were placed in a low-speed mixer, the stirring speed was set to 100 r / min, and the stirring time was 5 min; then 0.2 kg of lecithin (product of Archer Daniels Midland Company, USA) was added, the stirring speed was maintained at 100 r / min, and the stirring time was 10 min; then 0.2 kg of chitosan (product of Zhejiang Jinke Pharmaceutical Co., Ltd., food-grade chitosan with a deacetylation degree of 90%) was added, the stirring speed was increased to 200 r / min, and the stirring time was 10 min; finally, 0.2 kg of plant fiber aerogel (product of Anhui Keang Nano Technology Co., Ltd., model KNF-R) was added; the stirring speed was switched to low speed stirring at 100 r / min and the stirring time was 10 min; (2) Adding materials: Add the mixed materials into the steam forming mold cavity of the same size as in Application Example 7; (3) Steam molding: Close the mold and introduce steam into the mold cavity. The steam causes the beads to further expand and fuse with each other, filling the entire cavity. Maintain the steam pressure at 0.3 MPa for 90 seconds to fully mold the product. (4) Demolding: After molding is completed, stop introducing steam, open the mold, and use the demoulding mechanism to push the molded EPS foam insulation board out of the mold; (5) Annealing treatment: Transfer the EPS foam board to a 50℃ constant temperature drying room for constant temperature post-treatment for 5 hours.

[0232] Referring to ASTM C578 "Standard Specification for Rigid Cellular Polystyrene Thermal Insulation Materials", the compressive strength of the thermal insulation boards prepared in Example 7 and Comparative Application Examples 7-8 was tested, and the results are shown in Table 39.

[0233] Table 39: Compressive strength test results of thermal insulation boards

[0234] As can be seen from the table, the compressive strength of the thermal insulation board in Application Example 7 is superior to that of Comparative Application Examples 7-8. This is primarily due to the following: 1. The role of plant starch: Plant starch has excellent film-forming and adhesive properties, increasing the material's density. It also interacts with other components to form a stable network structure, enhancing the overall strength of the material. 2. The role of modified PLA: Polylactic acid (PLA) inherently possesses a certain strength, but its properties are further optimized by grafting hydroxyethyl methacrylate, caprolactone acrylate, and itaconic acid. The combination of modified PLA and plant starch enhances the material's toughness. This increased toughness helps disperse stress under compression, reducing brittle fracture and indirectly contributing to increased compressive strength, enabling the material to better withstand deformation without cracking. Furthermore, the molecular structure of the modified PLA interweaves with the plant starch, forming a tighter bond, enhancing the internal bonding strength of the material and, in turn, increasing compressive strength. 3. The innovative hot molding process: The multi-stage pressure control allows for initial compaction of the raw materials, expelling air, and initial shaping within the mold, creating favorable conditions for the subsequent main pressing stage. During the main compression stage, high pressure is applied to fully compact the plant-based composite foam material within the mold, creating a tighter bond between particles within the material, reducing porosity and increasing the material's compressive strength. Compared to traditional EPS steaming processes, the hot molding process allows for more precise control of the material's molding process, ensuring structural stability and improving the product's compressive strength.

[0235] With reference to GB / T 10294-2008 “Determination of steady-state thermal resistance and related properties of insulating materials – Guarded hot plate method”, the thermal insulation performance of the thermal insulation panels in Example 7 and Comparative Application Examples 7-8 were tested, and the results are shown in Table 40.

[0236] Table 40: Thermal insulation performance test results of thermal insulation boards

[0237] As can be seen from the table, the thermal insulation board in Application Example 7 performs better than the thermal insulation board in the comparative application example in terms of thermal insulation performance, better meeting the demand for efficient thermal insulation. The main reasons are: ① Plant starch forms a porous structure in the composite foam material. These pores hinder heat transfer. The closed porous structure reduces air convection, thereby reducing heat conduction and providing a certain insulation effect. At the same time, the interaction between starch molecules helps maintain the structural stability of the foam board, providing a good support framework for other components. Polylactic acid (PLA) itself has good physical properties and processing properties. After modification, compounding with plant starch can further improve the overall performance of the material. The combination of modified PLA and plant starch changes the material's microstructure, reduces heat conduction channels, and improves thermal insulation performance. ② The present invention uses multi-stage molding. The pre-compression stage can initially compact the raw materials, remove some air, and reduce bubble defects. The main compression stage, under appropriate pressure and temperature, fully fuses and foams the composite foam material, forming a uniform, dense foam structure with smaller pores and a more regular pore distribution, which can effectively prevent heat transfer. In contrast, in the traditional EPS steaming process in Application Example 8, the EPS beads expand and fuse under the action of steam, and the uneven pore distribution makes it easy for heat to be conducted through larger pores or channels between pores. The thermal insulation performance is not as good as the plant-based composite foam insulation board prepared by the hot molding process in Application Example 7.

[0238] With reference to JGJ / T 357-2015 “Technical Specification for On-site Testing of Heat Transfer Coefficient of Enclosure Structures”, the heat storage performance of the thermal insulation panels in Example 7 and Comparative Application Examples 7-8 were tested. The results are shown in Table 41.

[0239] Table 41: Thermal insulation board heat storage performance test results

[0240] As can be seen from the table, the thermal insulation board in Application Example 7 exhibits slower temperature changes under simulated diurnal temperature fluctuations compared to Comparative Application Examples 7 and 8, demonstrating superior heat storage capacity. This is primarily due to the following: ① The thermal inertia of the plant-based material: Application Example 7 utilizes a composite material composed primarily of plant starch and modified grafted hydroxyethyl methacrylate-caprolactone acrylate-itaconic acid-PLA. Both plant starch and PLA are high-molecular polymers with strong hydrogen bonds between their molecular chains, limiting molecular thermal motion. Compared to the linear carbon chain structure of EPS (polystyrene), this composite system requires more energy to activate molecular chain motion when heated, resulting in higher thermal inertia, slowing temperature conduction and reducing the rate of temperature change. ② Graft modification enhances interfacial effects: PLA is grafted with hydroxyethyl methacrylate, caprolactone acrylate, and itaconic acid to introduce polar groups and branched structures, significantly improving the compatibility between plant starch and PLA and forming a uniformly dispersed multiphase structure. During heat transfer, this structure hinders the heat flow conduction path through multiple reflections and scattering at the interface layer, further weakening the temperature change rate. In contrast, EPS is a single polymer system with a more direct heat conduction path. ③ Densification and molecular orientation regulation: The hot molding process of the present invention uses high temperature and high pressure to tightly fuse the composite foam material particles, eliminating internal voids and forming a continuous and dense network structure. At the same time, high pressure causes the polymer chains to align along the direction of pressure, enhancing the thermal resistance within the material. Comparative Application Example 8 uses steam molding, and the EPS beads are only fused through steam expansion. There are many incompletely fused interfaces within the EPS beads, resulting in higher heat conduction efficiency. ④ Structural fixation of synergistic additives: In the hot molding process of the present invention, additives such as polyvinyl alcohol adhesive and chitosan undergo cross-linking reactions under high temperature and high pressure, forming chemical bonds or physical entanglements with the main material, further stabilizing the microstructure of the foam board. This structural stability inhibits the relaxation of molecular chains at high temperatures and maintains the thermal insulation properties of the material, while the role of additives in the EPS steam molding process is relatively limited. ⑤ Limitations of EPS materials: EPS is a petroleum-based polymer material with high molecular chain flexibility. Its steam molding process relies on the expansion and fusion of beads, and uneven pores and voids are easily formed inside, resulting in an increase in heat conduction paths. In addition, EPS lacks the synergistic modification mechanism in the composite system, and it is difficult to significantly improve the thermal insulation properties through additives. Therefore, it is significantly weaker than the plant-based composite foaming material in Application Example 7 in controlling the temperature change rate.

[0241] Application Example 8: A method for preparing an organic compound fertilizer specifically for tuber crops, targeting the "low nitrogen, phosphorus and high potassium" requirements of tuber crops, based on the principle that potassium is the core requirement for tuber enlargement, designs an unbalanced ratio of N:P2O5:K2O = 1:0.8:2.7, with a total macronutrient content of ≥21% (conventional compound fertilizers are 1:1:1, 15-15-15, with a total macronutrient content of 45%); the steps are as follows: (1) Raw material recycling and processing: 1) Recycled material cleaning: The discarded packaging liner produced in Application Example 4 is screened to remove impurities. Then, light impurities such as dust and debris are removed through wind sorting equipment; 2) Crushing and grinding: Use a crusher to coarsely crush the waste packaging, then transfer it to a ball mill for fine grinding, and pass it through a 100-120 mesh sieve to obtain an organic sustained-release carrier powder; (2) Raw material mixing: 1) Initial premixing: Place 100 kg of pretreated organic slow-release carrier powder, 10 kg of superphosphate (containing P2O5 12-16%), and 5 kg of magnesium sulfate (MgO 1.8%) into a horizontal ribbon mixer. Set the mixer to a low speed of 200 r / min and stir for 10 minutes to ensure that the materials are initially evenly dispersed. 2) Secondary mixing: Add 12kg urea (containing 46% N) and 30kg potassium sulfate (containing 50% K2O) to the initial slow premixing in 1) and put them into a horizontal ribbon mixer. Set the low speed mixing to 300 r / min and stir for 10 minutes to ensure the materials are initially evenly dispersed. 3) Tertiary mixing: Add 0.6 kg of borax (containing B ≥ 11.0%) and 0.4 kg of zinc sulfate (containing Zn ≥ 35%) to the secondary slow premixing in 2) and set the stirring speed to 300 r / min for 10 minutes to form a mixture; (3) Molding processing: 1) Granulation: A disc granulator was used for granulation; the rotation speed was 20 r / min, and starch paste (10 wt% concentration) at 2% of the mixture was sprayed as a binder. The granulation pressure was 10 MPa, and the particle diameter was controlled at 2-5 mm. The particles were screened by a vibrating screen to separate the qualified particle size products. The undersized particles and powder were collected and sent back to the granulation process for re-granulation. The oversized particles were crushed and returned to the granulation process. 2) Drying: The wet granules are conveyed to a multi-layer fluidized bed dryer via a conveyor belt. Hot air at 70°C is used as the drying medium to rapidly dehydrate the granules in a fluidized state. The drying time is 30 minutes, and the moisture content is controlled to below 5% to prevent agglomeration and microbial growth. (4) Coating treatment: Use a coating machine and 65°C hot-melt paraffin as the coating material to evenly spray a thin layer of coating with a thickness of 0.1 mm on the surface of the particles to form a barrier layer to slow down the water-soluble release rate of the fertilizer.

[0242] Application Example 9: A method for preparing a special organic compound fertilizer for tuber crops, targeting the "low nitrogen, phosphorus and high potassium" requirements of tuber crops, based on the principle that potassium is the core requirement for tuber enlargement, designs an unbalanced ratio of N:P2O5:K2O = 1:0.8:2.5-2.8, with a total macronutrient content of ≥21% (conventional compound fertilizers use a 1:1:1 ratio, with a 15-15-15 ratio of 45% for total macronutrients). The steps are as follows: (1) Raw material recycling and processing: 1) Recycled material cleaning: The discarded packaging liner produced in Application Example 4 is screened to remove impurities. Then, light impurities such as dust and debris are removed through wind sorting equipment; 2) Crushing and grinding: Use a crusher to coarsely crush the waste packaging, then transfer it to a ball mill for fine grinding, and pass it through a 100-120 mesh sieve to obtain an organic sustained-release carrier powder; (2) Raw material mixing: 1) Initial premixing: Place 100 kg of pretreated organic slow-release carrier powder, 10 kg of superphosphate (containing P2O5 12-16%), and 5 kg of magnesium sulfate (MgO 1.8%) into a horizontal ribbon mixer. Set the mixer to a low speed of 200 r / min and stir for 10 minutes to ensure that the materials are initially evenly dispersed. 2) Secondary mixing: Add 12kg urea (containing 46% N) and 30kg potassium sulfate (containing 50% K2O) to the initial slow premixing in 1) and put them into a horizontal ribbon mixer. Set the low speed mixing to 300 r / min and stir for 10 minutes to ensure the materials are initially evenly dispersed. 3) Tertiary mixing: Add 0.6 kg of borax (containing B ≥ 11.0%) and 0.4 kg of zinc sulfate (containing Zn ≥ 35%) to the secondary slow premixing in 2) and set the stirring speed to 300 r / min for 10 minutes to form a mixture; (3) Molding processing: 1) Granulation: A disc granulator was used for granulation; the rotation speed was 20 r / min, and starch paste (10 wt% concentration) at 2% of the mixture was sprayed as a binder. The granulation pressure was 10 MPa, and the particle diameter was controlled at 2-5 mm. The particles were screened by a vibrating screen to separate the qualified particle size products. The undersized particles and powder were collected and sent back to the granulation process for re-granulation. The oversized particles were crushed and returned to the granulation process. 2) Drying: The wet granules are conveyed to a multi-layer fluidized bed dryer via a conveyor belt. Hot air at 70°C is used as the drying medium to rapidly dehydrate the granules in a fluidized state. The drying time is 30 minutes, and the moisture content is controlled to below 5% to prevent agglomeration and microbial growth. (4) Coating treatment: Use a coating machine and 65°C hot-melt paraffin as the coating material to evenly spray a thin layer of coating with a thickness of 0.15 mm on the surface of the particles to form a barrier layer to slow down the water-soluble release rate of the fertilizer.

[0243] The heavy metal elements, biuret content, Ascaris egg mortality rate, and fecal coliform count of the organic compound fertilizers in Examples 8 and 9 were measured to determine whether the fertilizers met the requirements for limits on toxic and hazardous substances in fertilizers (GB 38400-2019). The safety of the fertilizers was evaluated. The results are shown in Tables 42 to 45.

[0244] Table 42: Test results of heavy metal elements and biuret content in the organic compound fertilizer obtained in Application Example 8

[0245] Table 43: Test results of Ascaris egg mortality and fecal coliform group in the organic compound fertilizer obtained in Application Example 8

[0246] Table 44: Test results of heavy metal elements and biuret content in the organic compound fertilizer obtained in Application Example 9

[0247] Table 45: Test results of Ascaris egg mortality and fecal coliform group in the organic compound fertilizer obtained in Application Example 9

[0248] As can be seen from the table, the contents of various toxic and harmful substances in the organic compound fertilizer prepared by the present invention all comply with GB38400-2019 "Limit Requirements for Toxic and Harmful Substances in Fertilizers", indicating that the fertilizer has high safety during use and will not cause obvious pollution risks to the soil, environment and crops.

[0249] The organic compound fertilizers described in Application Examples 8 and 9 were used to grow potatoes and sweet potatoes. Experiments such as growth comparison, tuber yield and quality measurement, soil structure and property testing, and fertilizer nutrient release were conducted to test the performance of the organic compound fertilizers in promoting tuber crop growth, increasing yield and quality, improving soil structure and properties, and rationally releasing nutrients. Based on the principle of "equal total macronutrient input," the conventional compound fertilizer (45% total macronutrient content) should be applied at 50 kg per mu, while the special fertilizer of the present invention (21% total macronutrient content) should provide the same total amount of macronutrients, meaning the special fertilizer application rate is approximately 107 kg per mu.

[0250] Table 46: Basic information of experiments applied to potato cultivation

[0251] The experimental process and data records are as follows.

[0252] Table 47: Potato growth index measurements and yield

[0253] Yield analysis: The yield per unit area of ​​the experimental group is 3.77kg / m 2 (average 22.6 kg × 3), the control group was 3.05 kg / m 2 The experimental group's yield increased by approximately 24% compared to the control group (average 18.3 kg x 3). This demonstrates that organic compound fertilizers made from green composite foam materials can significantly increase potato yields, demonstrating their nutrient supply capacity. Due to their slow-release properties, the fertilizer provides a continuous and stable supply of nutrients throughout the potato's growth cycle, ensuring the nutritional needs of potatoes at each stage of growth and promoting tuber growth and expansion.

[0254] The core reason for the increased potato yield: The experimental and control groups received equal amounts of macronutrients. The specialized compound fertilizer used over 70% plant-based recycled material as a carrier, compared to over 50% clay in conventional fertilizers. ① Nutrient release better matches crop needs: Plant-based recycled material is rich in organic matter and has a porous structure, which absorbs nutrients and slowly releases them. This meets the needs of tuber crops, which require high potassium levels for stable growth in the early stages and later expansion. Clay-based carriers, on the other hand, lack this slow-release capacity and release nutrients quickly, potentially leading to rapid growth in the early stages and subsequent nutrient depletion, which in turn affects tuber expansion. ② Improved soil environment and root development: Degraded plant-based recycled material increases soil organic matter content, improves soil aggregate structure, enhances air permeability, and improves water and nutrient retention, all of which benefit potato root growth. Long-term use of clay-based carriers can lead to soil compaction and poor air permeability, restricting root expansion and affecting nutrient absorption efficiency. ③ Supplementing additional nutrients and bioactive substances: Plant-based recycled materials release bioactive substances such as amino acids and vitamins during degradation, which stimulate tuber cell division and expansion. They also provide a carbon source for soil microorganisms, promoting the growth of beneficial bacteria and improving soil fertility. Clay-based carriers only serve as fillers, lacking nutritional supplementation or bioregulation functions, and thus fail to provide additional growth support for crops. Plant-based carriers are more aligned with the growth characteristics of tuber crops, ultimately increasing yields by 24%.

[0255] Table 48: Potato tuber quality test results

[0256] Quality analysis: The starch, sugar, and vitamin content of the experimental group potatoes were significantly higher than those in the control group. Starch content increased by 5.2%, total sugar content increased by 4.76%, and vitamin C content increased by 7.3%. This demonstrates that the organic compound fertilizer of this invention not only increases yield but also effectively improves potato quality.

[0257] Table 49: Basic information of experiments applied to sweet potato cultivation

[0258] The experimental process and data records are as follows Table 50: Sweet potato growth index measurement and yield

[0259] Yield analysis: The yield per unit area of ​​the experimental group was 4.53 kg / m 2 (average 27.2 kg × 3), the control group was 3.75 kg / m 2 (average 22.5 kg x 3), the yield of the experimental group increased by approximately 20% compared to the control group. This demonstrates that the organic compound fertilizer made from the composite foam material of the present invention can significantly increase sweet potato yield, demonstrating its nutrient supply capacity. Due to its slow-release properties, the fertilizer can continuously and stably provide nutrients throughout the sweet potato growth cycle, ensuring the nutritional needs of the sweet potato at each growth stage and promoting tuber growth and expansion.

[0260] Table 51: Sweet potato tuber quality determination experimental results

[0261] Quality Analysis: The starch, sugar, and vitamin contents of the experimental sweet potatoes were significantly higher than those of the control group. Starch content increased by 3.74%, total sugar content increased by 6.62%, vitamin C content increased by 6.7%, and other vitamins increased by 5.77%. This demonstrates that the organic compound fertilizer of this invention not only increases yield but also effectively improves sweet potato quality.

[0262] The physical and chemical properties of the soil were tested before and after fertilization, and the results are shown in Tables 52 and 53.

[0263] Table 52: Soil physical properties test results

[0264] It can be seen from the data in the above table that during the entire experimental period, the soil bulk density of the test group that applied green composite foam material organic compound fertilizer continued to decrease, the porosity continued to increase, and the stability of aggregates significantly improved, indicating that the fertilizer can effectively loosen the soil and prevent soil compaction.

[0265] Table 53: Soil chemical properties test results

[0266] From the data in the above table, it can be seen that the pH value of the soil in the experimental group remained stable and appropriate, and the organic matter content and the nutrient contents of nitrogen, phosphorus, potassium, etc. were significantly higher than those in the control group, indicating that the fertilizer can not only improve the soil structure, but also has good slow-release properties, which can continuously provide nutrients for crops and maintain soil fertility.

Claims

1. A plant-based biodegradable foaming material, characterized in that: The raw materials include, by weight: 50-60 parts of plant particles, 20-25 parts of modified starch, 20-25 parts of modified polylactic acid, 8-12 parts of plasticizer, 1-2 parts of foaming agent, and 1-4 parts of nucleating agent; The plant particles are one or a mixture of corn particles, wheat particles, rice particles, oat particles, and coix seeds particles; The modified starch is acetylated distarch phosphate; The modified polylactic acid is polylactic acid grafted with hydroxyethyl methacrylate, caprolactone acrylate and itaconic acid; the mass of the hydroxyethyl methacrylate monomer, caprolactone acrylate monomer and itaconic acid monomer is 4-8%, 1-3% and 3-5% of the mass of the polylactic acid respectively.

2. The plant-based biodegradable foaming material according to claim 1, characterized in that: The plasticizer is acetyl tributyl citrate; The nucleating agent comprises montmorillonite and talc in a mass ratio of 1:1 to 2:1; The foaming agent comprises azodicarbonamide, ZnO and sodium bicarbonate; the mass ratio of azodicarbonamide to ZnO is 20:1-2; the mass ratio of azodicarbonamide to sodium bicarbonate is 5:5-6:

4.

3. The plant-based biodegradable foaming material according to claim 1, characterized in that: The particle size of the plant particles is 0.3-0.8 mm.

4. A method for preparing a plant-based degradable foaming material according to any one of claims 1 to 3, characterized in that: The steps include: (1) Preparation of plant particles: crushing the plant fruit to obtain plant particles; (2) Preparation of modified polylactic acid: polylactic acid, hydroxyethyl methacrylate monomer, caprolactone acrylate monomer, itaconic acid monomer, initiator, and antioxidant are mixed and melt-extruded, and the mixture is cooled, pelletized, and dried to obtain modified polylactic acid; (3) The raw materials are mixed evenly and then melt-extruded to obtain the plant-based biodegradable foaming material.

5. The method for preparing the plant-based degradable foaming material according to claim 4, wherein: The initiator described in step (2) is selected from one or more of diisopropylbenzene peroxide and di-tert-butyl peroxide; the antioxidant is selected from one or more of tea polyphenols, vitamin E, and tocopherol acetate; the masses of the initiator and the antioxidant are 0.5-2.0% and 0.5-1.0% of the mass of the polylactic acid, respectively.

6. A plant-based composite foam material, characterized in that: The components include, in parts by weight: 100 parts of the plant-based degradable foaming material according to any one of claims 1 to 3, 0.5 to 1.5 parts of an antioxidant, 0.5 to 1.5 parts of a flame retardant, 0.5 to 1 part of a mildewcide, 0.5 to 1 part of a waterproofing agent, 0.1 to 3 parts of a colorant, and 0.5 to 1 part of an antistatic agent.

7. The plant-based composite foam material according to claim 6, characterized in that: The antioxidant is vitamin E; the flame retardant is aluminum hydroxide; the mildew inhibitor is sodium diacetate; the waterproofing agent is carnauba wax; the colorant is natural fruit and vegetable powder; and the antistatic agent is stearic acid monoglyceride.

8. An application of the plant-based composite foam material according to claim 6 or 7, characterized in that: It is used in stuffing materials for plush dolls, children's toys, packaging products, foam cushioning coils, and thermal insulation products.

9. The use of the plant-based composite foam material according to claim 8, characterized in that: When used in children's toys, the raw materials of the children's toys include, by weight: 100 parts of the plant-based composite foam material, 10 to 20 parts of a plasticizer, 1 to 2 parts of a nucleating agent, 1 to 3 parts of an adhesive, 0.5 to 1 part of a waterproofing agent, and 0.1 to 3 parts of a colorant; The plasticizer is polylactic acid grafted with polyethylene glycol and a grafting monomer, and the grafting monomer is one or more of hydroxyethyl acrylate, itaconic acid, and acrylic acid; The mass of polyethylene glycol is 15-25% of the mass of polylactic acid, and the mass of the grafted monomer is 3-8% of the mass of polylactic acid.

10. The use of the plant-based composite foam material according to claim 9, characterized in that: The preparation method of the plasticizer comprises the following steps: mixing polylactic acid, polyethylene glycol, a grafting monomer, a catalyst, an initiator, and an antioxidant, and then melt-extruding the mixture; cooling, pelletizing, and drying the mixture to obtain the plasticizer; The catalyst is one or more of stannous octoate, tetraisopropyl titanate, and magnesium aluminum hydrotalcite; the initiator is one or more of dicumyl peroxide and di-tert-butyl peroxide; the antioxidant is one or more of tea polyphenols, vitamin E, and tocopherol acetate; The masses of the catalyst, initiator and antioxidant are 0.05-1.0%, 0.1-1.0% and 0.5-1.0% of the mass of the polylactic acid respectively.

11. The use of the plant-based composite foam material according to claim 8, characterized in that: When used in packaging products, the raw materials of the packaging products include, by weight: 100 parts of the plant-based composite foaming material, 2 to 5 parts of adhesive, and 0.1 to 3 parts of colorant.

12. The use of the plant-based composite foam material according to claim 8, characterized in that: When used in a foam cushioning coil, the foam cushioning coil comprises BOPLA films on both sides and composite foam particles arranged between the BOPLA films on both sides; the BOPLA films and the composite foam particles are composited by hot pressing; In parts by weight, the raw materials of the composite foam particles include: 100 parts of the plant-based composite foam material, 2 to 5 parts of an adhesive, and 5 to 15 parts of a toughening agent.

13. The use of the plant-based composite foam material according to claim 8, characterized in that: When used in thermal insulation products, the thermal insulation products are thermal insulation boxes or thermal insulation panels; The raw materials of the thermal insulation box include, by weight: 100 parts of the plant-based composite foam material, 10 to 30 parts of a plasticizer, 1 to 5 parts of a nucleating agent, 2 to 5 parts of an adhesive, 0.5 to 2 parts of a plant fiber aerogel, and 1 to 3 parts of a colorant; the plasticizer is polylactic acid grafted and modified with polyethylene glycol and a grafting monomer, the grafting monomer being one or more of hydroxyethyl acrylate, itaconic acid, and acrylic acid; the mass of the polyethylene glycol is 15 to 25% of the mass of the polylactic acid, and the mass of the grafting monomer is 3 to 8% of the mass of the polylactic acid; The raw materials of the thermal insulation board include: 100 parts of the plant-based composite foaming material, 0.2-0.5 parts of antioxidant, 2-5 parts of adhesive, 1-3 parts of chitosan, 0.5-2 parts of plant fiber aerogel, and 0.5-1.5 parts of lecithin.

14. A method for recycling the plant-based composite foam material according to any one of claims 6 or 7, characterized in that: The waste products containing the plant-based composite foaming material are cleaned and crushed to prepare recycled materials, and the recycled materials are used as a slow-release carrier for chemical fertilizers to prepare organic composite fertilizers.

15. The method for recycling plant-based composite foam materials according to claim 14, characterized in that: The organic compound fertilizer comprises compound fertilizer particles and a coating coated on the surface of the compound fertilizer particles; The material of the envelope is paraffin wax, and the thickness of the envelope is 0.05-0.15 mm; The raw materials of the compound fertilizer granules include, by weight, 100 parts of recycled materials, 8 to 10 parts of nitrogen fertilizer, 5 to 10 parts of phosphate fertilizer, 16 to 30 parts of potash fertilizer, 2 to 6 parts of magnesium fertilizer, 0.3 to 1 part of boron fertilizer, and 0.2 to 1 part of zinc fertilizer; the nitrogen fertilizer is urea, the phosphate fertilizer is superphosphate, the potash fertilizer is potassium sulfate, the magnesium fertilizer is magnesium sulfate, the boron fertilizer is borax, and the zinc fertilizer is zinc sulfate.

16. The method for recycling plant-based composite foam materials according to claim 15, characterized in that: The preparation method of the organic compound fertilizer comprises the following steps: A) mixing the raw materials of the compound fertilizer granules in proportion and then granulating them to obtain the compound fertilizer granules; B) spraying a coating material on the surface of the compound fertilizer particles and cooling the particles to obtain the organic compound fertilizer.

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