A starch-based composite foam material and its preparation and application

Abstract

The present invention belongs to the field of foaming materials, and in particular, relates to a starch-based composite foam material and its preparation and application. The preparation method provided by the present invention comprises the following steps: a) mixing starch, environmentally friendly ionic liquid, water, biological enzyme and starch modifier for reaction, and then mixing with plant fiber and toughening agent to continue reaction, removing the liquid phase, and obtaining a solid material; b) mixing the solid material, antioxidant, flame retardant, heat-resistant agent, nucleating agent and foaming agent, foaming and forming, and drying to obtain a starch-based composite foam material. The preparation method provided by the present invention can significantly improve the plasticizing effect on starch, form thermoplastic starch with a high degree of substitution, improve the compatibility of starch with reinforcement, toughening agent and other additives, and finally significantly improve the foaming ratio of starch, increase resilience, and obtain a starch-based material with good comprehensive mechanical properties; in addition, the preparation method provided by the present invention can reduce the use of toxic chemicals and is more environmentally friendly.

Description

Technical Field

[0001] The present invention belongs to the field of foaming materials, and in particular relates to a starch-based composite foam material and its preparation and application. Background Technology

[0002] In recent years, with the increasing shortage of oil resources and the increasingly serious environmental pollution, traditional petroleum-based plastics are no longer suitable, and new biodegradable materials have emerged. The current mainstream biodegradable materials include polylactic acid, polyadipate / butylene terephthalate, etc., but they are expensive, which limits the application and promotion of biodegradable materials.

[0003] In contrast, starch is cheap and abundant in source, and can be processed by traditional plastic processing technology, with broad application prospects. However, starch also has disadvantages such as easy aging, easy brittleness, and hydrophilicity. In order to balance applicability and biodegradability, researchers from various countries have focused on the plasticization and functional modification of starch. Good plasticity can not only improve the processing fluidity of starch, but also improve the performance of starch products. The difficulty in the research of starch products lies in the plasticization of starch and the compatibility with various functional additives.

[0004] Water is the simplest plasticizer, but due to its high volatility, the prepared thermoplastic starch has high requirements for relative humidity. Traditional plasticizers such as glycerol have limited plasticizing degree, and plasticized products are prone to recrystallization during storage, resulting in brittleness and hardening. In contrast, ionic liquids are more effective than glycerol in maintaining a uniform plasticized state during the regeneration process, but traditional imidazole ionic liquids have certain environmental pollution and are difficult to remove, so it is necessary to find alternative new environmentally friendly ionic liquids. In addition, studies have found that the plasticizing effect of a single ionic liquid is still limited.

[0005] In addition, in order to make starch meet the needs of industrial applications, it is necessary to modify the starch physically, chemically and functionally. The most commonly used methods are starch esterification, etherification, cross-linking, oxidation modification, etc. Among them, improving the modification efficiency and modification substitution degree are the top priorities in determining the performance of modified starch. At the same time, the compatibility of modified starch with reinforcement, toughening and other additives must also be taken into account, especially to avoid the use of toxic additives. The various current production plans have more or less problems, so it is necessary to develop new starch modification technologies and processing plans. SUMMARY OF THE INVENTION

[0006] In view of this, the purpose of the present invention is to provide a starch-based composite foam material and its preparation and application. The preparation method provided by the present invention can significantly improve the plasticization effect on starch, form thermoplastic starch with a high degree of substitution, improve the compatibility of starch with reinforcing agents, toughening agents and other additives, and ultimately significantly increase the foaming ratio of starch, increase the resilience, and obtain a starch-based material with good comprehensive mechanical properties; in addition, the preparation method provided by the present invention can reduce the use of toxic chemicals and has better environmental protection performance.

[0007] The present invention provides a preparation method of a starch-based composite foam material, comprising the following steps:

[0008] a) Mix and react starch, an environmentally friendly ionic liquid, water, a bio-enzyme and a starch modifier, then continue to react after mixing with plant fibers and a toughening agent, and remove the liquid phase to obtain a solid material;

[0009] The environmentally friendly ionic liquid is one or more of choline carboxylic acid ionic liquid, choline acetate ionic liquid, choline dioxidate ionic liquid, choline arginine ionic liquid, choline proline ionic liquid, choline phosphate ionic liquid, choline acetate ionic liquid, choline alanine ionic liquid, choline glycine ionic liquid and choline butyrate ionic liquid;

[0010] b) Mix the solid material, an antioxidant, a flame retardant, a heat-resistant agent, a nucleating agent and a foaming agent, foam mold, and dry to obtain a starch-based composite foam material.

[0011] Preferably, the starch is one or more of corn starch, rice starch, mung bean starch, pea starch, sweet potato starch, potato starch, chestnut starch and pumpkin starch;

[0012] The bio-enzyme is one or more of candida lipase, immobilized lipase, porcine pancreatic lipase, horseradish peroxidase and α-amylase;

[0013] The starch modifier is one or more of palmitic acid, n-butyl acetate, propylene glycol methyl ether acetate, stearic acid, succinic anhydride, lauric acid, rosin acid, sodium dodecylbenzenesulfonate and ε-caprolactone;

[0014] The plant fiber is one or more of coconut fiber, cotton fiber, reed fiber, straw fiber, ramie fiber, flax fiber, jute fiber, eucalyptus fiber, bamboo fiber, grass fiber and banana tree fiber;

[0015] The toughening agent is one or more of polyvinyl alcohol, poly(butylene adipate-co-terephthalate), poly(butylene succinate) and poly(propylene carbonate).

[0016] Preferably, the antioxidant is one or more of antioxidant DLTDP, antioxidant 626, antioxidant 1010, antioxidant 1075, antioxidant 2246, and tea polyphenols;

[0017] The flame retardant is one or more of chlorinated paraffin, antimony trioxide, aluminum hydroxide, and magnesium hydroxide;

[0018] The heat-resistant agent is ceramic powder;

[0019] The nucleating agent is one or more of silica, talc powder, titanium dioxide, calcium carbonate, zinc oxide, and montmorillonite;

[0020] The foaming agent is water.

[0021] Preferably, based on 100 parts by weight of the starch, the total amount of the environmentally friendly ionic liquid and water is 300 - 500 parts by weight, and the mass ratio of the environmentally friendly ionic liquid to water is 1:(1 - 3); the amount of the biological enzyme is 5 - 8 parts by weight; the amount of the starch modifier is 15 - 20 parts by weight; the amount of the plant fiber is 5 - 20 parts by weight; the amount of the toughening agent is 5 - 30 parts by weight; the amount of the antioxidant is 1 - 3 parts by weight; the amount of the flame retardant is 0.1 - 2 parts by weight; the amount of the heat-resistant agent is 0.1 - 2 parts by weight; the amount of the nucleating agent is 2 - 10 parts by weight; the amount of the foaming agent is 5 - 15 parts by weight.

[0022] Preferably, the temperature of the mixing reaction is 55 - 65 °C; the time of the mixing reaction is 2 - 4 h; the temperature of the continuous reaction is 55 - 65 °C; the time of the continuous reaction is 1 - 2 h.

[0023] Preferably, the temperature of the foaming and molding is 145 - 165 °C; the pressure of the foaming and molding is 3 - 5 MPa; the time of the foaming and molding is 16 - 20 min.

[0024] Preferably, a waterproofing agent is further added during the mixing in step b); the waterproofing agent is one or more of acrylate copolymer, palmitic acid, silicone waterproofing agent, dispersed rosin size, and paraffin.

[0025] Preferably, the foaming and molding is carried out in a mold pre-coated with a mold release agent; the mold release agent is one or more of silicone oil, zinc stearate, magnesium stearate, and liquid paraffin.

[0026] The present invention provides a starch-based composite foam material prepared by the preparation method according to the above technical solution.

[0027] The present invention provides a starch-based composite foam board, the material of which is the starch-based composite foam material according to the above technical solution.

[0028] Compared with the prior art, the present invention provides a starch-based composite foam material and its preparation and application. The preparation method provided by the present invention comprises the following steps: a) mixing starch, an environmentally friendly ionic liquid, water, a bio-enzyme and a starch modifier for reaction, then mixing with plant fibers and a toughening agent and continuing the reaction, and removing the liquid phase to obtain a solid material; the environmentally friendly ionic liquid is one or more of choline carboxylate ionic liquid, choline acetate ionic liquid, choline dioxalate ionic liquid, choline arginine ionic liquid, choline proline ionic liquid, choline phosphate ionic liquid, choline acetate ionic liquid, choline alanine ionic liquid, choline glycine ionic liquid and choline butyrate ionic liquid; b) mixing the solid material, an antioxidant, a flame retardant, a heat-resistant agent, a nucleating agent and a foaming agent, foaming and molding, and drying to obtain the starch-based composite foam material. The preparation method provided by the present invention uses a mixture of an environmentally friendly ionic liquid and water to plasticize and modify starch, significantly improving the plasticization effect on starch, efficiently catalyzing and modifying starch by adding a bio-enzyme to form thermoplastic starch with a high degree of substitution; at the same time, the plasticizing modification system composed of the environmentally friendly ionic liquid, water and bio-enzyme can also synchronously modify plant fibers and promote the reaction with the toughening agent to improve compatibility; in addition, compared with traditional ionic liquids such as imidazole-based ionic liquids, the environmentally friendly ionic liquid is safe, pollution-free and has better environmental protection performance. By optimizing and improving the preparation method of the starch-based composite foam material, the present invention can significantly improve the foaming ratio of starch, increase the resilience, and finally improve the comprehensive mechanical properties of the starch-based material. Detailed Embodiments

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0030] The present invention provides a preparation method of a starch-based composite foam material, comprising the following steps:

[0031] a) Mixing starch, an environmentally friendly ionic liquid, water, a bio-enzyme and a starch modifier for reaction, then mixing with plant fibers and a toughening agent and continuing the reaction, and removing the liquid phase to obtain a solid material;

[0032] b) Mixing the solid material, an antioxidant, a flame retardant, a heat-resistant agent, a nucleating agent and a foaming agent, foaming and molding, and drying to obtain the starch-based composite foam material.

[0033] In the preparation method provided by the present invention, the starch is preferably one or more of corn starch, rice starch, mung bean starch, pea starch, sweet potato starch, potato starch, millet starch and pumpkin starch; the mesh number of the starch is preferably 200-400 mesh, and specifically can be 200 mesh, 210 mesh, 220 mesh, 230 mesh, 240 mesh, 250 mesh, 260 mesh, 270 mesh, 280 mesh, 290 mesh, 300 mesh, 310 mesh, 320 mesh, 330 mesh, 340 mesh, 350 mesh, 360 mesh, 370 mesh, 380 mesh, 390 mesh or 400 mesh.

[0034] In an embodiment provided by the present invention, the starch is rice starch and sweet potato starch; the mass ratio of the rice starch to the sweet potato starch is preferably 1:(0.5-2), and more preferably 1:1.

[0035] In an embodiment provided by the present invention, the starch is mung bean starch and pea starch; the mass ratio of the mung bean starch to the pea starch is preferably 1:(0.5-2), and more preferably 1:1.

[0036] In an embodiment provided by the present invention, the starch is rice starch and potato starch; the mass ratio of the rice starch to the potato starch is preferably 1:(0.5-2), and more preferably 1:1.

[0037] In an embodiment provided by the present invention, the starch is millet starch and pumpkin starch; the mass ratio of the millet starch to the pumpkin starch is preferably 1:(0.5-2), and more preferably 1:1.

[0038] In the preparation method provided by the present invention, the environmentally friendly ionic liquid is one or more of choline carboxylic acid ionic liquid, choline acetate ionic liquid, choline dioxalate ionic liquid, choline arginine ionic liquid, choline proline ionic liquid, choline phosphate ionic liquid, choline acetate ionic liquid, choline alanine ionic liquid, choline glycine ionic liquid and choline butyrate ionic liquid.

[0039] In an embodiment provided by the present invention, the environmentally friendly ionic liquid is choline acetate ionic liquid and choline dioxalate ionic liquid; the mass ratio of the choline acetate ionic liquid to the choline dioxalate ionic liquid is preferably 1:(0.5-2), and more preferably 1:1.

[0040] In an embodiment provided by the present invention, the environmentally friendly ionic liquid is choline butyrate ionic liquid and choline alanine ionic liquid; the mass ratio of the choline butyrate ionic liquid to the choline alanine ionic liquid is preferably 1:(0.5-2), and more preferably 1:1.

[0041] In the preparation method provided by the present invention, the water includes, but is not limited to, one or more of tap water, distilled water, deionized water, high-purity water, and reverse osmosis water.

[0042] In the preparation method provided by the present invention, based on 100 parts by weight of the starch, the total amount of the environmentally friendly ionic liquid and water is preferably 300 - 500 parts by weight, specifically 300 parts by weight, 310 parts by weight, 320 parts by weight, 330 parts by weight, 340 parts by weight, 350 parts by weight, 360 parts by weight, 370 parts by weight, 380 parts by weight, 390 parts by weight, 400 parts by weight, 410 parts by weight, 420 parts by weight, 430 parts by weight, 440 parts by weight, 450 parts by weight, 460 parts by weight, 470 parts by weight, 480 parts by weight, 490 parts by weight, or 500 parts by weight; the mass ratio of the environmentally friendly ionic liquid to water is preferably 1:(1 - 3), specifically 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9, or 1:3.

[0043] In the preparation method provided by the present invention, before the starch, environmentally friendly ionic liquid, and water participate in the mixing reaction, pre-mixing is preferably performed first; the rotation speed of the pre-mixing is preferably 100 - 300 revolutions per minute, specifically 100 revolutions per minute, 120 revolutions per minute, 150 revolutions per minute, 170 revolutions per minute, 200 revolutions per minute, 230 revolutions per minute, 250 revolutions per minute, 270 revolutions per minute, or 300 revolutions per minute; the temperature of the pre-mixing is preferably 60 - 80 °C, specifically 60 °C, 62 °C, 65 °C, 67 °C, 70 °C, 72 °C, 75 °C, 78 °C, or 80 °C; the time of the pre-mixing is preferably 40 - 60 minutes, specifically 40 minutes, 42 minutes, 45 minutes, 47 minutes, 50 minutes, 52 minutes, 55 minutes, 57 minutes, or 60 minutes.

[0044] In the preparation method provided by the present invention, the bio-enzyme is preferably one or more of Candida lipase, immobilized lipase, porcine pancreatic lipase, horseradish peroxidase, and α-amylase.

[0045] In an embodiment provided by the present invention, the bio-enzyme is immobilized lipase and α-amylase; the mass ratio of the immobilized lipase to α-amylase is preferably (1 - 5):3, more preferably 3.5:3.

[0046] In an embodiment provided by the present invention, the bio-enzyme is immobilized lipase and horseradish peroxidase; the mass ratio of the immobilized lipase to the horseradish peroxidase is preferably (4 - 10):6, and more preferably 6.5:6.

[0047] In an embodiment provided by the present invention, the bio-enzyme is α-amylase and porcine pancreatic lipase; the mass ratio of the α-amylase to the porcine pancreatic lipase is preferably 1:(0.5 - 2), and more preferably 1:1.

[0048] In the preparation method provided by the present invention, based on 100 parts by weight of the starch, the dosage of the bio-enzyme is preferably 5 - 8 parts by weight, specifically it can be 5 parts by weight, 5.1 parts by weight, 5.2 parts by weight, 5.3 parts by weight, 5.4 parts by weight, 5.5 parts by weight, 5.6 parts by weight, 5.7 parts by weight, 5.8 parts by weight, 5.9 parts by weight, 6 parts by weight, 6.1 parts by weight, 6.2 parts by weight, 6.3 parts by weight, 6.4 parts by weight, 6.5 parts by weight, 6.6 parts by weight, 6.7 parts by weight, 6.8 parts by weight, 6.9 parts by weight, 7 parts by weight, 7.1 parts by weight, 7.2 parts by weight, 7.3 parts by weight, 7.4 parts by weight, 7.5 parts by weight, 7.6 parts by weight, 7.7 parts by weight, 7.8 parts by weight, 7.9 parts by weight or 8 parts by weight.

[0049] In the preparation method provided by the present invention, the starch modifier is preferably one or more of palmitic acid, n-butyl acetate, propylene glycol methyl ether acetate, stearic acid, succinic anhydride, lauric acid, rosin acid, sodium dodecylbenzenesulfonate and ε-caprolactone.

[0050] In an embodiment provided by the present invention, the starch modifier is n-butyl acetate and propylene glycol methyl ether acetate; the mass ratio of the n-butyl acetate to the propylene glycol methyl ether acetate is preferably (5 - 12):9, and more preferably 8.5:9.

[0051] In an embodiment provided by the present invention, the starch modifier is n-butyl acetate and stearic acid; the mass ratio of the n-butyl acetate to the stearic acid is preferably 1:(0.5 - 2), and more preferably 1:1.

[0052] In an embodiment provided by the present invention, the starch modifier is lauric acid and sodium dodecylbenzenesulfonate; the mass ratio of the lauric acid to the sodium dodecylbenzenesulfonate is preferably 1:(0.5 - 2), and more preferably 1:1.

[0053] In the preparation method provided by the present invention, based on 100 parts by weight of the starch, the amount of the starch modifier is preferably 15 to 20 parts by weight, specifically 15 parts by weight, 15.5 parts by weight, 16 parts by weight, 16.5 parts by weight, 17 parts by weight, 17.5 parts by weight, 18 parts by weight, 18.5 parts by weight, 19 parts by weight, 19.5 parts by weight or 20 parts by weight.

[0054] In the preparation method provided by the present invention, the rotation speed of the mixing reaction is preferably 100 to 300 revolutions per minute, specifically 100 revolutions per minute, 120 revolutions per minute, 150 revolutions per minute, 170 revolutions per minute, 200 revolutions per minute, 230 revolutions per minute, 250 revolutions per minute, 270 revolutions per minute or 300 revolutions per minute; the temperature of the mixing reaction is preferably 55 to 65 °C, specifically 55 °C, 56 °C, 57 °C, 57.5 °C, 58 °C, 59 °C, 60 °C, 61 °C, 62 °C, 62.5 °C, 63 °C, 64 °C or 65 °C; the time of the mixing reaction is preferably 2 to 4 h, specifically 2 h, 2.3 h, 2.5 h, 2.7 h, 3 h, 3.2 h, 3.5 h, 3.7 h or 4 h.

[0055] In the preparation method provided by the present invention, the plant fiber is preferably one or more of coconut fiber, cotton fiber, reed fiber, straw fiber, ramie fiber, flax fiber, jute fiber, eucalyptus fiber, bamboo fiber, grass fiber and banana tree fiber; the length of the plant fiber is preferably 2 to 4 mm, specifically 2 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, 3 mm, 3.1 mm, 3.2 mm, 3.3 mm, 3.4 mm, 3.5 mm, 3.6 mm, 3.7 mm, 3.8 mm, 3.9 mm or 4 mm; the diameter of the plant fiber is preferably 30 to 50 μm, specifically 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, 36 μm, 37 μm, 38 μm, 39 μm, 40 μm, 41 μm, 42 μm, 43 μm, 44 μm, 45 μm, 46 μm, 47 μm, 48 μm, 49 μm or 50 μm.

[0056] In an embodiment provided by the present invention, the plant fiber is ramie fiber and straw fiber; the mass ratio of the ramie fiber to the straw fiber is preferably (5 to 12):9, more preferably 8:9.

[0057] In an embodiment provided by the present invention, the plant fiber is grass fiber and bamboo fiber; the mass ratio of the grass fiber to the bamboo fiber is preferably 1:(0.5 to 2), more preferably 1:1.

[0058] In the preparation method provided by the present invention, based on 100 parts by weight of the starch, the amount of the plant fiber is preferably 5 to 20 parts by weight, specifically 5 parts by weight, 5.5 parts by weight, 6 parts by weight, 6.5 parts by weight, 7 parts by weight, 7.5 parts by weight, 8 parts by weight, 8.5 parts by weight, 9 parts by weight, 9.5 parts by weight, 10 parts by weight, 10.5 parts by weight, 11 parts by weight, 11.5 parts by weight, 12 parts by weight, 12.5 parts by weight, 13 parts by weight, 13.5 parts by weight, 14 parts by weight, 14.5 parts by weight, 15 parts by weight, 15.5 parts by weight, 16 parts by weight, 16.5 parts by weight, 17 parts by weight, 17.5 parts by weight, 18 parts by weight, 18.5 parts by weight, 19 parts by weight, 19.5 parts by weight or 20 parts by weight.

[0059] In the preparation method provided by the present invention, the toughening agent is preferably one or more of polyvinyl alcohol, polybutylene adipate / terephthalate, polybutylene succinate and polypropylene carbonate; the molar ratio of the aliphatic polyester (BA) repeating unit to the aromatic polyester (BT) repeating unit in the polybutylene adipate / terephthalate is preferably (60:40) to (40:60), specifically 60:40, 50:50 or 40:60; the mesh number of the toughening agent is preferably 200 to 400 mesh, specifically 200 mesh, 210 mesh, 220 mesh, 230 mesh, 240 mesh, 250 mesh, 260 mesh, 270 mesh, 280 mesh, 290 mesh, 300 mesh, 310 mesh, 320 mesh, 330 mesh, 340 mesh, 350 mesh, 360 mesh, 370 mesh, 380 mesh, 390 mesh or 400 mesh; the weight-average molecular weight of the toughening agent is preferably 150,000 to 400,000, specifically 150,000, 160,000, 170,000, 180,000, 190,000, 200,000, 210,000, 220,000, 230,000, 240,000, 250,000, 260,000, 270,000, 280,000, 290,000, 300,000, 310,000, 320,000, 330,000, 340,000, 350,000, 360,000, 370,000, 380,000, 390,000 or 400,000.

[0060] In an embodiment provided by the present invention, the toughening agent is polyvinyl alcohol and polybutylene adipate / terephthalate; the mass ratio of the polyvinyl alcohol to the polybutylene adipate / terephthalate is preferably 1:(0.5 to 2), more preferably 1:1.

[0061] In an embodiment provided by the present invention, the toughening agent is polybutylene succinate and polypropylene carbonate; the mass ratio of the polybutylene succinate to the polypropylene carbonate is preferably 1:(0.5 to 2), more preferably 1:1.

[0062] In the preparation method provided by the present invention, based on 100 parts by weight of the starch, the amount of the toughening agent is preferably 5 to 30 parts by weight, specifically 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight or 30 parts by weight.

[0063] In the preparation method provided by the present invention, the rotation speed of the continuous reaction is preferably 100 to 300 revolutions per minute, specifically 100 revolutions per minute, 120 revolutions per minute, 150 revolutions per minute, 170 revolutions per minute, 200 revolutions per minute, 230 revolutions per minute, 250 revolutions per minute, 270 revolutions per minute or 300 revolutions per minute; the temperature of the continuous reaction is preferably 55 to 65 °C, specifically 55 °C, 56 °C, 57 °C, 58 °C, 59 °C, 60 °C, 61 °C, 62 °C, 63 °C, 64 °C or 65 °C; the time of the continuous reaction is preferably 1 to 2 h, specifically 1 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h or 2 h.

[0064] In the preparation method provided by the present invention, the method for removing the liquid phase is preferably centrifugal separation; the rotation speed of the centrifugal separation is preferably 5000 to 10000 revolutions per minute, specifically 5000 revolutions per minute, 6000 revolutions per minute, 7000 revolutions per minute, 7500 revolutions per minute, 8000 revolutions per minute, 9000 revolutions per minute or 10000 revolutions per minute. In the present invention, before performing the centrifugal separation, it is preferably to perform washing first, and the washing reagent is preferably anhydrous ethanol. In the present invention, after completing the centrifugal separation, it is preferably to perform drying, and the drying method is preferably drying by baking.

[0065] In the preparation method provided by the present invention, after obtaining the solid material, it is preferably crushed into powder.

[0066] In the preparation method provided by the present invention, the antioxidant is preferably one or more of antioxidant DLTDP, antioxidant 626, antioxidant 1010, antioxidant 1075, antioxidant 2246 and tea polyphenols.

[0067] In an embodiment provided by the present invention, the antioxidant is antioxidant DLTDP and tea polyphenols; the mass ratio of antioxidant DLTDP and tea polyphenols is preferably 1:(0.5 to 2), more preferably 1:1.

[0068] In an embodiment provided by the present invention, the antioxidant is antioxidant 1075 and antioxidant 2246; the mass ratio of antioxidant 1075 to antioxidant 2246 is preferably 1:(0.5 - 2), more preferably 1:1.

[0069] In the preparation method provided by the present invention, based on the amount of the starch being 100 parts by weight, the amount of the antioxidant is preferably 1 - 3 parts by weight, specifically it can be 1 part by weight, 1.1 parts by weight, 1.2 parts by weight, 1.3 parts by weight, 1.4 parts by weight, 1.5 parts by weight, 1.6 parts by weight, 1.7 parts by weight, 1.8 parts by weight, 1.9 parts by weight, 2 parts by weight, 2.1 parts by weight, 2.2 parts by weight, 2.3 parts by weight, 2.4 parts by weight, 2.5 parts by weight, 2.6 parts by weight, 2.7 parts by weight, 2.8 parts by weight, 2.9 parts by weight or 3 parts by weight.

[0070] In the preparation method provided by the present invention, the flame retardant is preferably one or more of chlorinated paraffin, antimony trioxide, aluminum hydroxide and magnesium hydroxide.

[0071] In an embodiment provided by the present invention, the flame retardant is antimony trioxide and aluminum hydroxide; the mass ratio of antimony trioxide to aluminum hydroxide is preferably 1:(0.5 - 2), more preferably 1:1.

[0072] In the preparation method provided by the present invention, based on the amount of the starch being 100 parts by weight, the amount of the flame retardant is preferably 0.1 - 2 parts by weight, specifically it can be 0.1 part by weight, 0.2 part by weight, 0.3 part by weight, 0.4 part by weight, 0.5 part by weight, 0.6 part by weight, 0.7 part by weight, 0.8 part by weight, 0.9 part by weight, 1 part by weight, 1.1 parts by weight, 1.2 parts by weight, 1.3 parts by weight, 1.4 parts by weight, 1.5 parts by weight, 1.6 parts by weight, 1.7 parts by weight, 1.8 parts by weight, 1.9 parts by weight or 2 parts by weight.

[0073] In the preparation method provided by the present invention, the heat-resistant agent is preferably ceramic powder, more preferably zirconium boride (ZrB 2 ) ceramic powder; the mesh number of the heat-resistant agent is preferably 4000 - 5000 mesh, specifically it can be 4000 mesh, 4100 mesh, 4200 mesh, 4250 mesh, 4300 mesh, 4400 mesh, 4500 mesh, 4600 mesh, 4700 mesh, 4750 mesh, 4800 mesh, 4900 mesh or 5000 mesh.

[0074] In the preparation method provided by the present invention, based on 100 parts by weight of the starch, the amount of the heat-resistant agent is preferably 0.1 to 2 parts by weight, specifically, it can be 0.1 part by weight, 0.2 part by weight, 0.3 part by weight, 0.4 part by weight, 0.5 part by weight, 0.6 part by weight, 0.7 part by weight, 0.8 part by weight, 0.9 part by weight, 1 part by weight, 1.1 part by weight, 1.2 part by weight, 1.3 part by weight, 1.4 part by weight, 1.5 part by weight, 1.6 part by weight, 1.7 part by weight, 1.8 part by weight, 1.9 part by weight or 2 parts by weight.

[0075] In the preparation method provided by the present invention, the nucleating agent is preferably one or more of silica, talcum powder, titanium dioxide, calcium carbonate, zinc oxide and montmorillonite; the mesh number of the nucleating agent is preferably 3000 to 4000 mesh, specifically, it can be 3000 mesh, 3100 mesh, 3200 mesh, 3250 mesh, 3300 mesh, 3400 mesh, 3500 mesh, 3600 mesh, 3700 mesh, 3750 mesh, 3800 mesh, 3900 mesh or 4000 mesh.

[0076] In an embodiment provided by the present invention, the nucleating agent is calcium carbonate and zinc oxide; the mass ratio of the calcium carbonate to the zinc oxide is preferably (1 to 3):6, more preferably 2:6.

[0077] In an embodiment provided by the present invention, the nucleating agent is talcum powder and titanium dioxide; the mass ratio of the talcum powder to the titanium dioxide is preferably 1:(0.5 to 2), more preferably 1:1.

[0078] In an embodiment provided by the present invention, the nucleating agent is montmorillonite and calcium carbonate; the mass ratio of the montmorillonite to the calcium carbonate is preferably 1:(0.5 to 2), more preferably 1:1.

[0079] In the preparation method provided by the present invention, based on 100 parts by weight of the starch, the amount of the nucleating agent is preferably 2 to 10 parts by weight, specifically, it can be 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, 4.5 parts by weight, 5 parts by weight, 5.5 parts by weight, 6 parts by weight, 6.5 parts by weight, 7 parts by weight, 7.5 parts by weight, 8 parts by weight, 8.5 parts by weight, 9 parts by weight, 9.5 parts by weight or 10 parts by weight.

[0080] In the preparation method provided by the present invention, the foaming agent is preferably water, including but not limited to one or more of tap water, distilled water, deionized water, high-purity water and reverse osmosis water, more preferably deionized water.

[0081] In the preparation method provided by the present invention, based on the amount of the starch being 100 parts by weight, the amount of the foaming agent is preferably 5 to 15 parts by weight, specifically, it can be 5 parts by weight, 5.5 parts by weight, 6 parts by weight, 6.5 parts by weight, 7 parts by weight, 7.5 parts by weight, 8 parts by weight, 8.5 parts by weight, 9 parts by weight, 9.5 parts by weight, 10 parts by weight, 10.5 parts by weight, 11 parts by weight, 11.5 parts by weight, 12 parts by weight, 12.5 parts by weight, 13 parts by weight, 13.5 parts by weight, 14 parts by weight, 14.5 parts by weight or 15 parts by weight.

[0082] In the preparation method provided by the present invention, during the mixing process in step b), a waterproofing agent is preferably further added; the waterproofing agent is preferably one or more of acrylate copolymer, palmitic acid, silicone waterproofing agent, dispersed rosin size and paraffin wax; the copolymerization monomers corresponding to the acrylate copolymer are preferably butyl acrylate (BA) and methyl methacrylate (MMA), and the mass ratio of butyl acrylate to methyl methacrylate is preferably (1 - 5):2, more preferably 3:2; the weight-average molecular weight of the acrylate copolymer is preferably 60,000 - 80,000, specifically, it can be 60,000, 65,000, 70,000, 75,000 or 80,000; the active ingredient in the silicone waterproofing agent is preferably potassium methyl silicate.

[0083] In an embodiment provided by the present invention, the waterproofing agent is dispersed rosin size and silicone waterproofing agent; the mass ratio of dispersed rosin size to silicone waterproofing agent is preferably 1:(0.5 - 2), more preferably 1:1.

[0084] In an embodiment provided by the present invention, the waterproofing agent is dispersed rosin size and acrylate copolymer; the mass ratio of dispersed rosin size to acrylate copolymer is preferably 1:(0.5 - 2), more preferably 1:1.

[0085] In the preparation method provided by the present invention, based on the amount of the starch being 100 parts by weight, the amount of the waterproofing agent is preferably 0 to 5 parts by weight, specifically, it can be 0 parts by weight, 0.5 parts by weight, 1 part by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, 4.5 parts by weight or 5 parts by weight.

[0086] In the preparation method provided by the present invention, the rotation speed of the mixing in step b) is preferably 600 - 800 revolutions per minute, and specifically can be 600 revolutions per minute, 650 revolutions per minute, 700 revolutions per minute, 750 revolutions per minute or 800 revolutions per minute; the temperature of the mixing is preferably 30 - 50 °C, and specifically can be 30 °C, 32 °C, 35 °C, 37 °C, 40 °C, 42 °C, 45 °C, 47 °C or 50 °C; the time of the mixing is preferably 5 - 20 minutes, and specifically can be 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes or 20 minutes.

[0087] In the preparation method provided by the present invention, the foam molding is preferably carried out in a mold pre-coated with a mold release agent; the mold release agent is preferably one or more of silicone oil, zinc stearate, magnesium stearate and liquid paraffin.

[0088] In an embodiment provided by the present invention, the mold release agent is zinc stearate and magnesium stearate; the mass ratio of zinc stearate to magnesium stearate is preferably 1:(0.5 - 2), and more preferably 1:1.

[0089] In an embodiment provided by the present invention, the mold release agent is liquid paraffin and silicone oil; the mass ratio of liquid paraffin to silicone oil is preferably 1:(0.5 - 2), and more preferably 1:1.

[0090] In the preparation method provided by the present invention, based on the amount of the starch being 100 parts by weight, the amount of the mold release agent is preferably 1 - 5 parts by weight, and specifically can be 1 part by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, 4.5 parts by weight or 5 parts by weight.

[0091] In the preparation method provided by the present invention, the temperature of the foam molding is preferably 145 - 165 °C, and specifically can be 145 °C, 147 °C, 150 °C, 152 °C, 155 °C, 157 °C, 160 °C, 162 °C or 165 °C; the pressure of the foam molding is preferably 3 - 5 MPa, and specifically can be 3 MPa, 3.2 MPa, 3.5 MPa, 3.7 MPa, 4 MPa, 4.2 MPa, 4.5 MPa, 4.7 MPa or 5 MPa; the time of the foam molding is preferably 16 - 20 minutes, and specifically can be 16 minutes, 16.5 minutes, 17 minutes, 17.5 minutes, 18 minutes, 18.5 minutes, 19 minutes, 19.5 minutes or 20 minutes.

[0092] In the preparation method provided by the present invention, the drying method is preferably drying by baking; the drying temperature is preferably 90-100 °C, and specifically can be 90 °C, 91 °C, 92 °C, 92.5 °C, 93 °C, 94 °C, 95 °C, 96 °C, 97 °C, 98 °C, 99 °C or 100 °C.

[0093] The present invention also provides a starch-based composite foam material, which is prepared by the preparation method described in the above technical solution.

[0094] The present invention also provides a starch-based composite foam board, and the material of the starch-based composite foam board is the starch-based composite foam material described in the above technical solution.

[0095] By optimizing and improving the preparation method of the starch-based composite foam material, the present invention can significantly improve the plasticization effect of starch, form thermoplastic starch with a high degree of substitution, improve the compatibility of starch with reinforcing agents, toughening agents and other additives, and ultimately significantly increase the foaming ratio of starch, increase the resilience, and obtain a starch-based material with good comprehensive mechanical properties. Specifically, the key points of the technical solution of the present invention are as follows: 1) Using a mixture of an environmentally friendly ionic liquid and water to promote the plasticization and modification process of starch, improving the thermoplasticity and modification degree of substitution of starch, and further using biological enzymes to improve the reaction efficiency and the properties of starch on this basis, so as to prepare a starch foaming material with high resilience; 2) The plasticizing and modifying system composed of an environmentally friendly ionic liquid, water and biological enzymes can also simultaneously promote the surface modification of plant fibers, promote the reaction with modified starch, and improve the strength of the composite foam material; 3) This plasticizing and modifying system can also play a synergistic promoting role, which can promote the reaction of modified starch, modified plant fibers and toughening agents, improve the compatibility between components in the composite material, and improve the overall performance of the composite foam material.

[0096] The technical solution provided by the present invention has at least the following advantages: 1) Using the method of the present invention to prepare a starch-based composite foam material, it is completely biodegradable and has excellent overall performance, good resilience, and can be applied to fields such as thermal insulation boards and takeout packaging boxes; 2) The starch in the starch-based composite foam material prepared according to the method of the present invention has a high degree of plasticization, and the reaction with the reinforcing agent (plant fiber) and the toughening agent is sufficient, with a high interfacial bonding force and excellent performance; 3) The preparation method provided by the present invention uses an environmentally friendly ionic liquid, water and biological enzymes as a plasticizing and modifying system, which not only has high reaction efficiency but also is completely environmentally friendly and pollution-free; 4) The preparation method provided by the present invention can use water as a foaming agent, with better environmental protection; 5) The preparation method provided by the present invention is simple, efficient, environmentally friendly, and the product has excellent performance, laying a foundation for further expanding the application fields of bio-based degradable foam materials.

[0097] For clarity, the following is a detailed description through the following examples and comparative examples. In the following examples and comparative examples of the present invention, the specific evaluation methods for various properties are as follows:

[0098] (1) Determination of resilience:

[0099] Cut the foam sheet into 10×10 mm squares, measure the thickness of the foam block with a high-precision thickness gauge, then clamp the foam block with the thickness gauge and compress it to 1 / 2 of its original thickness. After 10 s, release it, and measure the thickness of the foam block again after 1 min. Substitute the values into the formula to calculate the resilience of the foam block, and the result is the average of 10 sets of test values; Resilience = (diameter after rebound - 1 / 2 diameter before compression) ÷ (1 / 2 diameter before compression) × 100%.

[0100] (2) Determination of compression modulus:

[0101] Cut the starch foam sheet into samples of a certain size with a blade, and measure its length, width, and height. The compression rate is 5 mm / min, and it is tested using a universal material testing machine. Calculate the compression modulus of the starch foam through the initial linear part of the compression stress-strain curve, and take the average of 5 samples tested.

[0102] (3) Determination of impact strength:

[0103] The impact strength is measured with reference to GB / T 1843—2008 "Determination of Izod impact strength of plastics". The kinetic energy of the impact pendulum is 3.25 J. A total of 5 groups of samples are taken for the test, and the final result is the average of 5 groups of samples.

[0104] (4) Determination of foaming ratio:

[0105] The foaming ratio of the starch foam is the density of the foam material matrix divided by the density of the starch foam material. The density of the foam material is calculated from the mass and volume, where the volume is measured by the liquid displacement method, and the density of the foam substrate is measured by a similar method. The average of 10 samples is taken for the calculated density value.

[0106] (5) Determination of density:

[0107] The apparent density is tested with reference to GB / T 6343—2009 "Determination of apparent density of cellular plastics and rubbers". Measure the values of the length and diameter of the sample respectively, and calculate the total volume of the sample. To reduce experimental errors, a total of 5 groups of samples are taken for the test, and the final result is the average of 5 groups of samples; Density = sample mass ÷ sample volume.

[0108] (6) Determination of water contact angle:

[0109] After drying the foam, it was brittle broken after being cooled by liquid nitrogen, the cut section was cut, and fixed on the glass slide with double-sided tape. The hydrophilicity of the sample was measured by a contact angle tester, and each sample was tested 5 times. The result was the average value of the 5 test values.

[0110] (7) Determination of flame retardancy:

[0111] The flame retardancy was measured with reference to GB / T 2408—2008 Plastics - Determination of burning behaviour - Horizontal and vertical methods. The vertical burning tester was used to test the flame retardancy grade of the sample. A total of 5 groups of samples were taken for the test, and the result was the average value of the 5 test values.

[0112] Example 1

[0113] 225 parts by weight of tap water and 75 parts by weight of choline carboxylic acid ionic liquid were added to the reaction kettle. After mixing evenly, 100 parts by weight of 200-mesh corn starch was added. It was fully stirred at 60 °C for 40 min, and the stirring speed was 100 r / min. After the starch was fully dissolved, the temperature was lowered to 55 °C, 5 parts by weight of Candida lipase and 15 parts by weight of palmitic acid were added, and stirring was carried out at the same rotation speed for the modification reaction for 2 h; then 5 parts by weight of coconut fibers with a length of 2 mm and a diameter of 30 μm and 5 parts by weight of polyvinyl alcohol with a mesh number of 200 mesh and a weight average molecular weight of 150,000 were added, and stirring reaction was continued at the same rotation speed and temperature for 1 h; after the reaction was completed, it was cooled to room temperature, washed 3 times with absolute ethanol, and separated and purified by a high-speed centrifuge with the rotation speed set at 5000 r / min. The precipitate was dried and then crushed.

[0114] The above-mentioned dried and crushed materials were transferred to a high-speed mixer, and 0.5 part by weight of antioxidant 626, 0.1 part by weight of chlorinated paraffin, 0.1 part by weight of 4000-mesh zirconium boride ceramic powder, 2 parts by weight of 3000-mesh silica, and 5 parts by weight of deionized water were added respectively. After fully mixing for 5 min, the mixing temperature was set at 30 °C, and the rotation speed was set at 600 r / min; the surface of the mold wall was coated with 1 silicone oil, and then the above-mentioned mixture was filled into the mold, foamed and expanded at 145 °C for 16 min, the pressure was 3 MPa, and after drying at 90 °C, it was demolded to obtain the starch-based composite foam board.

[0115] The starch-based composite foam board obtained above was tested, and the results were: the resilience rate was 60%, the compression modulus was 4.76 MPa, the impact strength was 0.51 kJ / m 2 , the foaming ratio was 9.3 times, and the density was 0.144 g / cm 3 , the water contact angle was 64.2°, and the flame retardancy grade was HB.

[0116] Example 2

[0117] Add 250 parts by weight of distilled water and 100 parts by weight of choline glycine ionic liquid to the reaction kettle. After mixing evenly, add 50 parts by weight of rice starch and 50 parts by weight of sweet potato starch with a mesh size of 250. Stir well at 65 °C for 45 min, with a stirring speed of 150 revolutions / min. After the starch is fully dissolved, lower the temperature to 57.5 °C, add 6 parts by weight of horseradish peroxidase and 16.5 parts by weight of succinic anhydride, and stir at the same rotation speed for 2.5 h for the modification reaction; then add 9 parts by weight of jute fibers with a length of 2.5 mm and a diameter of 35 μm and 10 parts by weight of polybutylene succinate with a mesh size of 250 and a weight average molecular weight of 200,000. Continue to stir and react for 1.2 h at the same rotation speed and temperature; after the reaction is completed, cool to room temperature, wash 3 times with absolute ethanol, and perform separation and purification in a high-speed centrifuge with the rotation speed set at 6000 revolutions / min. Dry the precipitate and then crush it.

[0118] Transfer the above dried and crushed material to a high-speed mixer, add 1 part by weight of dispersed rosin size, 1.5 parts by weight of antioxidant 1010, 0.5 part by weight of antimony trioxide, 0.5 part by weight of zirconium boride ceramic powder with a mesh size of 4250, 4 parts by weight of silica with a mesh size of 3250, and 7.5 parts by weight of deionized water, and mix well for 9 min. Set the mixing temperature at 35 °C and the rotation speed at 650 revolutions / min; apply 2 parts by weight of zinc stearate to the surface of the mold wall, then fill the above mixture into the mold, place it at 150 °C for foaming and expansion for 17 min, with a pressure of 3.5 MPa, and dry and demold at 92.5 °C to obtain the starch-based composite foam board.

[0119] Test the starch-based composite foam board obtained above, and the results are as follows: the rebound rate is 80%, the compression modulus is 6.57 MPa, and the impact strength is 0.67 kJ / m 2 , the foaming ratio is 13.8 times, and the density is 0.103 g / cm 3 , the water contact angle is 81.9°, and the flame retardant grade is HB grade.

[0120] Example 3

[0121] Add 265 parts by weight of reverse osmosis water and 135 parts by weight of choline acetate ionic liquid into a reaction kettle. After mixing evenly, add 50 parts by weight of mung bean starch and 50 parts by weight of pea starch with a mesh size of 300. Stir well at 70 °C for 50 min, with a stirring speed of 200 r / min. After the starch is fully dissolved, lower the temperature to 60 °C, add 3.5 parts by weight of immobilized lipase, 3 parts by weight of α-amylase, 8.5 parts by weight of n-butyl acetate, and 9 parts by weight of propylene glycol methyl ether acetate, and stir at the same rotation speed for 3 h for the modification reaction; then add 13 parts by weight of ramie fibers with a length of 3 mm and a diameter of 40 μm and 18 parts by weight of polybutylene adipate / terephthalate with a mesh size of 300 and a weight average molecular weight of 250,000 (where the molar ratio of the aliphatic polyester (BA) repeating unit to the aromatic polyester (BT) repeating unit is 60:40); at the same rotation speed and temperature, continue to stir and react for 1.5 h; after the reaction is completed, cool to room temperature, wash 3 times with absolute ethanol, separate and purify in a high-speed centrifuge with a rotation speed set at 7500 r / min, and dry and crush the precipitate.

[0122] Transfer the above dried and crushed materials to a high-speed mixer, and add 2.5 parts by weight of an organosilicon waterproofing agent (brand: YR-Y18, active ingredient: potassium methyl silicate, manufacturer: Nanjing Yingrun New Materials Technology Co., Ltd.), 2 parts by weight of antioxidant DLTDP, 1 part by weight of aluminum hydroxide, 1 part by weight of zirconium boride ceramic powder with a mesh size of 4500, 2 parts by weight of calcium carbonate with a mesh size of 3500, 6 parts by weight of zinc oxide with a mesh size of 3500, and 10 parts by weight of deionized water, and mix well for 13 min. Set the mixing temperature at 40 °C and the rotation speed at 700 r / min; apply 3 parts by weight of liquid paraffin to the surface of the mold wall, then fill the above mixture into the mold, place it at 155 °C for foaming and expansion for 18 min under a pressure of 4 MPa, dry at 95 °C and then demold to obtain a starch-based composite foam board.

[0123] Test the starch-based composite foam board obtained above, and the results are as follows: the rebound rate is 85%, the compression modulus is 7.32 MPa, the impact strength is 0.80 kJ / m 2 , the foaming ratio is 18.3 times, and the density is 0.081 g / cm 3 , the water contact angle is 97.4°, and the flame retardant grade is V-2.

[0124] Example 4

[0125] Add 270 parts by weight of deionized water, 90 parts by weight of choline acetate ionic liquid, and 90 parts by weight of choline dioxalate ionic liquid to a reaction kettle. After mixing evenly, add 50 parts by weight of rice starch and 50 parts by weight of potato starch with a mesh size of 350. Stir well at 75 °C for 55 min, with a stirring speed of 250 revolutions per minute. After the starch is fully dissolved, lower the temperature to 62.5 °C, add 6.5 parts by weight of immobilized lipase, 6 parts by weight of horseradish peroxidase, 9 parts by weight of n-butyl acetate, and 9 parts by weight of stearic acid, and stir at the same rotation speed for a modification reaction of 3.5 h; then add 8 parts by weight of ramie fibers with a length of 3.5 mm and a diameter of 45 μm and 9 parts by weight of straw fibers, and then add 12 parts by weight of polyvinyl alcohol with a mesh size of 350 and a weight average molecular weight of 300,000 and 12 parts by weight of polybutylene adipate / terephthalate (where the molar ratio of the aliphatic polyester (BA) repeating unit to the aromatic polyester (BT) repeating unit is 50:50). Continue to stir and react for 1.8 h at the same rotation speed and temperature; after the reaction is completed, cool to room temperature, wash 3 times with absolute ethanol, separate and purify in a high-speed centrifuge with a rotation speed set at 9000 revolutions per minute, and dry and crush the precipitate.

[0126] Transfer the above dried and crushed materials to a high-speed mixer, and add 2 parts by weight of dispersed rosin size, 2 parts by weight of silicone waterproofing agent YR-Y18, 1.25 parts by weight of antioxidant DLTDP, 1.25 parts by weight of tea polyphenols, 0.7 parts by weight of antimony trioxide, 0.7 parts by weight of aluminum hydroxide, 1.5 parts by weight of zirconium boride ceramic powder with a mesh size of 4750, 4 parts by weight of talc powder with a mesh size of 3750, 4 parts by weight of titanium dioxide with a mesh size of 3750, and 12.5 parts by weight of deionized water, and mix well for 18 min. Set the mixing temperature at 45 °C and the rotation speed at 750 revolutions per minute; apply 2 parts by weight of zinc stearate and 2 parts by weight of magnesium stearate to the surface of the mold wall, then fill the above mixture into the mold, place it at 160 °C for foaming and expansion for 19 min, with a pressure of 4.5 MPa, and dry and demold at 98 °C to obtain a starch-based composite foam board.

[0127] Test the starch-based composite foam board obtained above, and the results are as follows: the rebound rate is 93%, the compression modulus is 8.19 MPa, the impact strength is 0.91 kJ / m 2 , the foaming ratio is 27.2 times, the density is 0.054 g / cm 3 , the water contact angle is 110.2°, and the flame retardant grade is V-2.

[0128] Example 5

[0129] Add 250 parts by weight of high-purity water, 125 parts by weight of choline butyrate ionic liquid, and 125 parts by weight of choline alanine ionic liquid to the reaction kettle. After mixing evenly, add 50 parts by weight of corn starch and 50 parts by weight of pumpkin starch with a mesh size of 400. Stir well at 80 °C for 60 min, and the stirring speed is 300 revolutions per minute. After the starch is fully dissolved, lower the temperature to 65 °C, add 4 parts by weight of α-amylase, 4 parts by weight of porcine pancreatic lipase, 10 parts by weight of lauric acid, and 10 parts by weight of sodium dodecylbenzenesulfonate, and stir at the same rotation speed for 4 h for the modification reaction; then add 10 parts by weight of straw fiber with a length of 4 mm and a diameter of 50 μm and 10 parts by weight of bamboo fiber, and then add 15 parts by weight of polybutylene succinate and 15 parts by weight of poly(propylene carbonate) with a mesh size of 400 and a weight-average molecular weight of 400,000. Continue to stir and react for 2 h at the same rotation speed and temperature; after the reaction is completed, cool to room temperature, wash 3 times with absolute ethanol, and carry out separation and purification in a high-speed centrifuge with the rotation speed set at 10,000 revolutions per minute. Dry the precipitate and then crush it.

[0130] Transfer the above dried and crushed material to a high-speed mixer, add 2.5 parts by weight of dispersed rosin size and 2.5 parts by weight of acrylate copolymer (weight-average molecular weight is 70,000, made by copolymerization of butyl acrylate (BA) and methyl methacrylate (MMA), and the mass ratio of BA to MMA is 3:2), then add 1.5 parts by weight of antioxidant 1075, 1.5 parts by weight of antioxidant 2246, 2 parts by weight of magnesium hydroxide, 2 parts by weight of zirconium boride ceramic powder with a mesh size of 5000, 5 parts by weight of montmorillonite with a mesh size of 4000, 5 parts by weight of calcium carbonate with a mesh size of 4000, and 15 parts by weight of deionized water, and mix well for 20 min. Set the mixing temperature at 50 °C and the rotation speed at 800 revolutions per minute; apply 2.5 parts by weight of liquid paraffin and 2.5 parts by weight of silicone oil to the surface of the mold wall, then fill the above mixture into the mold, place it at 165 °C for foaming and swelling for 20 min under a pressure of 5 MPa, dry it at 100 °C and then demold to obtain the starch-based composite foam board.

[0131] Test the starch-based composite foam board obtained above, and the results are as follows: the rebound rate is 91%, the compression modulus is 8.03 MPa, the impact strength is 0.84 kJ / m 2 , the foaming ratio is 24.1 times, and the density is 0.061 g / cm 3 , the water contact angle is 106.5°, and the flame retardant grade is V-1.

[0132] Example 6

[0133] Prepare the starch-based composite foam board according to the method of Example 2, except that "50 parts by weight of rice starch and 50 parts by weight of sweet potato starch" is replaced with 100 parts by weight of rice starch.

[0134] Test the prepared starch-based composite foam board, and the results are as follows: the rebound rate is 81%, the compression modulus is 6.34 MPa, and the impact strength is 0.66 kJ / m 2 , the foaming ratio is 12.4 times, and the density is 0.113 g / cm 3 , the water contact angle is 80.5°, and the flame retardant grade is HB.

[0135] Example 7

[0136] Prepare the starch-based composite foam board according to the method of Example 2, except that "50 parts by weight of rice starch and 50 parts by weight of sweet potato starch" is replaced with 100 parts by weight of sweet potato starch.

[0137] Test the prepared starch-based composite foam board, and the results are as follows: the rebound rate is 79%, the compression modulus is 6.47 MPa, and the impact strength is 0.63 kJ / m 2 , the foaming ratio is 13.4 times, and the density is 0.108 g / cm 3 , the water contact angle is 82.3°, and the flame retardant grade is HB.

[0138] Example 8

[0139] Prepare the starch-based composite foam board according to the method of Example 3, except that "50 parts by weight of mung bean starch and 50 parts by weight of pea starch" is replaced with 100 parts by weight of mung bean starch.

[0140] Test the prepared starch-based composite foam board, and the results are as follows: the rebound rate is 83%, the compression modulus is 7.22 MPa, and the impact strength is 0.75 kJ / m 2 , the foaming ratio is 16.7 times, and the density is 0.087 g / cm 3 , the water contact angle is 93.4°, and the flame retardant grade is HB.

[0141] Example 9

[0142] Prepare the starch-based composite foam board according to the method of Example 3, except that "50 parts by weight of mung bean starch and 50 parts by weight of pea starch" is replaced with 100 parts by weight of pea starch.

[0143] Test the prepared starch-based composite foam board, and the results are as follows: the rebound rate is 84%, the compression modulus is 7.25 MPa, and the impact strength is 0.72 kJ / m 2, the foaming ratio is 18.9 times, and the density is 0.076 g / cm 3 , the water contact angle is 96.4°, and the flame retardant grade is HB grade.

[0144] Example 10

[0145] Refer to the method of Example 3 to prepare the starch-based composite foam board, the difference is that "3.5 parts by weight of immobilized lipase and 3 parts by weight of α-amylase" is replaced by 6.5 parts by weight of immobilized lipase.

[0146] Test the prepared starch-based composite foam board, and the results are: the resilience rate is 84%, the compression modulus is 7.29 MPa, and the impact strength is 0.73 kJ / m 2 , the foaming ratio is 16.2 times, and the density is 0.089 g / cm 3 , the water contact angle is 96.2°, and the flame retardant grade is V-2 grade.

[0147] Example 11

[0148] Refer to the method of Example 3 to prepare the starch-based composite foam board, the difference is that "3.5 parts by weight of immobilized lipase and 3 parts by weight of α-amylase" is replaced by 6.5 parts by weight of α-amylase.

[0149] Test the prepared starch-based composite foam board, and the results are: the resilience rate is 85%, the compression modulus is 7.02 MPa, and the impact strength is 0.77 kJ / m 2 , the foaming ratio is 17.3 times, and the density is 0.084 g / cm 3 , the water contact angle is 98.2°, and the flame retardant grade is V-2 grade.

[0150] Example 12

[0151] Refer to the method of Example 3 to prepare the starch-based composite foam board, the difference is that "8.5 parts by weight of n-butyl acetate and 9 parts by weight of propylene glycol methyl ether acetate" is replaced by 17.5 parts by weight of n-butyl acetate.

[0152] Test the prepared starch-based composite foam board, and the results are: the resilience rate is 82%, the compression modulus is 7.24 MPa, and the impact strength is 0.69 kJ / m 2 , the foaming ratio is 16.9 times, and the density is 0.086 g / cm 3 , the water contact angle is 95.0°, and the flame retardant grade is HB grade.

[0153] Example 13

[0154] Prepare the starch-based composite foam board according to the method of Example 3, except that "8.5 parts by weight of n-butyl acetate and 9 parts by weight of propylene glycol methyl ether acetate" is replaced with 17.5 parts by weight of propylene glycol methyl ether acetate.

[0155] Test the prepared starch-based composite foam board, and the results are as follows: the resilience rate is 84%, the compression modulus is 7.47 MPa, and the impact strength is 0.75 kJ / m 2 , the foaming ratio is 17.7 times, and the density is 0.082 g / cm 3 , the water contact angle is 96.7°, and the flame retardant grade is V-2.

[0156] Example 14

[0157] Prepare the starch-based composite foam board according to the method of Example 4, except that "80 parts by weight of choline acetate ionic liquid and 80 parts by weight of choline dioxalate ionic liquid" is replaced with 160 parts by weight of choline acetate ionic liquid.

[0158] Test the prepared starch-based composite foam board, and the results are as follows: the resilience rate is 91%, the compression modulus is 8.16 MPa, and the impact strength is 0.77 kJ / m 2 , the foaming ratio is 24.3 times, and the density is 0.061 g / cm 3 , the water contact angle is 110.5°, and the flame retardant grade is V-2.

[0159] Example 15

[0160] Prepare the starch-based composite foam board according to the method of Example 4, except that "80 parts by weight of choline acetate ionic liquid and 80 parts by weight of choline dioxalate ionic liquid" is replaced with 160 parts by weight of choline dioxalate ionic liquid.

[0161] Test the prepared starch-based composite foam board, and the results are as follows: the resilience rate is 92%, the compression modulus is 8.09 MPa, and the impact strength is 0.85 kJ / m 2 , the foaming ratio is 26.2 times, and the density is 0.057 g / cm 3 , the water contact angle is 107.2°, and the flame retardant grade is V-2..

[0162] Example 16

[0163] Prepare the starch-based composite foam board according to the method of Example 4, except that "50 parts by weight of rice starch and 50 parts by weight of potato starch" is replaced with 100 parts by weight of rice starch.

[0164] The prepared starch-based composite foam board was tested, and the results were as follows: the resilience rate was 90%, the compression modulus was 7.88 MPa, and the impact strength was 0.77 kJ / m 2 , the foaming ratio was 25.5 times, and the density was 0.059 g / cm 3 , the water contact angle was 105.8°, and the flame retardant grade was V-2.

[0165] Example 17

[0166] Refer to the method of Example 4 to prepare the starch-based composite foam board, the difference is that "50 parts by weight of rice starch and 50 parts by weight of potato starch" is replaced by 100 parts by weight of potato starch.

[0167] The prepared starch-based composite foam board was tested, and the results were as follows: the resilience rate was 91%, the compression modulus was 7.95 MPa, and the impact strength was 0.86 kJ / m 2 , the foaming ratio was 26.0 times, and the density was 0.057 g / cm 3 , the water contact angle was 107.9°, and the flame retardant grade was V-2.

[0168] Example 18

[0169] Refer to the method of Example 4 to prepare the starch-based composite foam board, the difference is that "6.5 parts by weight of immobilized lipase and 6 parts by weight of horseradish peroxidase" is replaced by 12.5 parts by weight of immobilized lipase.

[0170] The prepared starch-based composite foam board was tested, and the results were as follows: the resilience rate was 93%, the compression modulus was 8.12 MPa, and the impact strength was 0.88 kJ / m 2 , the foaming ratio was 26.5 times, and the density was 0.056 g / cm 3 , the water contact angle was 108.7°, and the flame retardant grade was V-2.

[0171] Example 19

[0172] Refer to the method of Example 4 to prepare the starch-based composite foam board, the difference is that "6.5 parts by weight of immobilized lipase and 6 parts by weight of horseradish peroxidase" is replaced by 12.5 parts by weight of horseradish peroxidase.

[0173] The prepared starch-based composite foam board was tested, and the results were as follows: the resilience rate was 92%, the compression modulus was 8.01 MPa, and the impact strength was 0.80 kJ / m 2 , the foaming ratio was 24.7 times, and the density was 0.058 g / cm 3 , the water contact angle was 107.2°, and the flame retardant grade was V-2.

[0174] Example 20

[0175] Prepare the starch-based composite foam board according to the method of Reference Example 4, except that "9 parts by weight of n-butyl acetate and 9 parts by weight of stearic acid" is replaced with 18 parts by weight of n-butyl acetate.

[0176] Test the prepared starch-based composite foam board, and the results are as follows: the resilience rate is 92%, the compression modulus is 8.20 MPa, and the impact strength is 0.78 kJ / m 2 , the foaming ratio is 28.9 times, and the density is 0.052 g / cm 3 , the water contact angle is 108.9°, and the flame retardant grade is V-2.

[0177] Example 21

[0178] Prepare the starch-based composite foam board according to the method of Reference Example 4, except that "9 parts by weight of n-butyl acetate and 9 parts by weight of stearic acid" is replaced with 18 parts by weight of stearic acid.

[0179] Test the prepared starch-based composite foam board, and the results are as follows: the resilience rate is 91%, the compression modulus is 7.89 MPa, and the impact strength is 0.82 kJ / m 2 , the foaming ratio is 25.3 times, and the density is 0.059 g / cm 3 , the water contact angle is 107.0°, and the flame retardant grade is V-2.

[0180] Example 22

[0181] Prepare the starch-based composite foam board according to the method of Reference Example 4, except that "8 parts by weight of ramie fiber and 9 parts by weight of straw fiber" is replaced with 17 parts by weight of ramie fiber.

[0182] Test the prepared starch-based composite foam board, and the results are as follows: the resilience rate is 93%, the compression modulus is 8.07 MPa, and the impact strength is 0.80 kJ / m 2 , the foaming ratio is 24.2 times, and the density is 0.061 g / cm 3 , the water contact angle is 111.5°, and the flame retardant grade is V-2.

[0183] Example 23

[0184] Prepare the starch-based composite foam board according to the method of Reference Example 4, except that "8 parts by weight of ramie fiber and 9 parts by weight of straw fiber" is replaced with 17 parts by weight of straw fiber.

[0185] The prepared starch-based composite foam board was tested, and the results were as follows: the rebound rate was 90%, the compression modulus was 7.99 MPa, and the impact strength was 0.83 kJ / m 2 , the foaming ratio was 25.7 times, and the density was 0.058 g / cm 3 , the water contact angle was 107.7°, and the flame retardant grade was V-2.

[0186] Example 24

[0187] The starch-based composite foam board was prepared with reference to the method of Example 4, except that "12 parts by weight of polyvinyl alcohol and 12 parts by weight of polybutylene adipate / terephthalate" was replaced with 24 parts by weight of polyvinyl alcohol.

[0188] The prepared starch-based composite foam board was tested, and the results were as follows: the rebound rate was 92%, the compression modulus was 8.09 MPa, and the impact strength was 0.86 kJ / m 2 , the foaming ratio was 24.2 times, and the density was 0.062 g / cm 3 , the water contact angle was 100.6°, and the flame retardant grade was V-2.

[0189] Example 25

[0190] The starch-based composite foam board was prepared with reference to the method of Example 4, except that "12 parts by weight of polyvinyl alcohol and 12 parts by weight of polybutylene adipate / terephthalate" was replaced with 24 parts by weight of polybutylene adipate / terephthalate, and the molar ratio of the aliphatic polyester (BA) repeating unit to the aromatic polyester (BT) repeating unit was preferably 50:50.

[0191] The prepared starch-based composite foam board was tested, and the results were as follows: the rebound rate was 91%, the compression modulus was 8.45 MPa, and the impact strength was 0.80 kJ / m 2 , the foaming ratio was 22.6 times, and the density was 0.066 g / cm 3 , the water contact angle was 112.7°, and the flame retardant grade was V-2.

[0192] Example 26

[0193] The starch-based composite foam board was prepared with reference to the method of Example 5, except that "100 parts by weight of choline butyrate ionic liquid and 100 parts by weight of choline alanine ionic liquid" was replaced with 200 parts by weight of choline butyrate ionic liquid.

[0194] The prepared starch-based composite foam board was tested, and the results were as follows: the rebound rate was 90%, the compression modulus was 8.04 MPa, and the impact strength was 0.77 kJ / m 2, the foaming ratio is 23.1 times and the density is 0.064 g / cm 3 , the water contact angle is 107.1° and the flame retardant grade is V-2.

[0195] Example 27

[0196] Refer to the method of Example 5 to prepare the starch-based composite foam board, the difference is that "100 parts by weight of choline butyrate ionic liquid and 100 parts by weight of choline alanine ionic liquid" is replaced by 200 parts by weight of choline alanine ionic liquid.

[0197] Test the prepared starch-based composite foam board, and the results are: the resilience rate is 89%, the compression modulus is 7.85 MPa, and the impact strength is 0.80 kJ / m 2 , the foaming ratio is 24.1 times and the density is 0.061 g / cm 3 , the water contact angle is 104.5° and the flame retardant grade is V-2.

[0198] Example 28

[0199] Refer to the method of Example 5 to prepare the starch-based composite foam board, the difference is that "50 parts by weight of corn starch and 50 parts by weight of pumpkin starch" is replaced by 100 parts by weight of corn starch.

[0200] Test the prepared starch-based composite foam board, and the results are: the resilience rate is 91%, the compression modulus is 8.00 MPa, and the impact strength is 0.85 kJ / m 2 , the foaming ratio is 23.3 times and the density is 0.064 g / cm 3 , the water contact angle is 103.5° and the flame retardant grade is V-1.

[0201] Example 29

[0202] Refer to the method of Example 5 to prepare the starch-based composite foam board, the difference is that "50 parts by weight of corn starch and 50 parts by weight of pumpkin starch" is replaced by 100 parts by weight of pumpkin starch.

[0203] Test the prepared starch-based composite foam board, and the results are: the resilience rate is 88%, the compression modulus is 7.77 MPa, and the impact strength is 0.79 kJ / m 2 , the foaming ratio is 22.7 times and the density is 0.065 g / cm 3 , the water contact angle is 104.7° and the flame retardant grade is V-2.

[0204] Example 30

[0205] Prepare the starch-based composite foam board according to the method of Example 5, except that "4 parts by weight of α-amylase and 4 parts by weight of porcine pancreatic lipase" is replaced with 8 parts by weight of α-amylase.

[0206] Test the prepared starch-based composite foam board, and the results are as follows: the rebound rate is 91%, the compression modulus is 8.25 MPa, and the impact strength is 0.76 kJ / m 2 , the foaming ratio is 24.3 times, and the density is 0.061 g / cm 3 , the water contact angle is 107.8°, and the flame retardant grade is V-1.

[0207] Example 31

[0208] Prepare the starch-based composite foam board according to the method of Example 5, except that "4 parts by weight of α-amylase and 4 parts by weight of porcine pancreatic lipase" is replaced with 8 parts by weight of porcine pancreatic lipase.

[0209] Test the prepared starch-based composite foam board, and the results are as follows: the rebound rate is 90%, the compression modulus is 8.33 MPa, and the impact strength is 0.81 kJ / m 2 , the foaming ratio is 24.8 times, and the density is 0.060 g / cm 3 , the water contact angle is 103.5°, and the flame retardant grade is V-1.

[0210] Example 32

[0211] Prepare the starch-based composite foam board according to the method of Example 5, except that "10 parts by weight of lauric acid and 10 parts by weight of sodium dodecylbenzenesulfonate" is replaced with 20 parts by weight of lauric acid.

[0212] Test the prepared starch-based composite foam board, and the results are as follows: the rebound rate is 92%, the compression modulus is 8.11 MPa, and the impact strength is 0.73 kJ / m 2 , the foaming ratio is 22.6 times, and the density is 0.068 g / cm 3 , the water contact angle is 102.9°, and the flame retardant grade is V-1.

[0213] Example 33

[0214] Prepare the starch-based composite foam board according to the method of Example 5, except that "10 parts by weight of lauric acid and 10 parts by weight of sodium dodecylbenzenesulfonate" is replaced with 20 parts by weight of sodium dodecylbenzenesulfonate.

[0215] Test the prepared starch-based composite foam board, and the results are as follows: the rebound rate is 90%, the compression modulus is 8.38 MPa, and the impact strength is 0.80 kJ / m2 , the foaming ratio is 25.5 times and the density is 0.058 g / cm 3 , the water contact angle is 106.6°, and the flame retardant grade is V-1.

[0216] Example 34

[0217] Refer to the method of Example 5 to prepare the starch-based composite foam board, the difference is that "10 parts by weight of grass fiber and 10 parts by weight of bamboo fiber" is replaced by 20 parts by weight of grass fiber.

[0218] Test the prepared starch-based composite foam board, and the results are: the rebound rate is 91%, the compression modulus is 7.99 MPa, and the impact strength is 0.76 kJ / m 2 , the foaming ratio is 22.2 times and the density is 0.067 g / cm 3 , the water contact angle is 100.2°, and the flame retardant grade is V-2.

[0219] Example 35

[0220] Refer to the method of Example 5 to prepare the starch-based composite foam board, the difference is that "10 parts by weight of grass fiber and 10 parts by weight of bamboo fiber" is replaced by 20 parts by weight of bamboo fiber.

[0221] Test the prepared starch-based composite foam board, and the results are: the rebound rate is 90%, the compression modulus is 7.97 MPa, and the impact strength is 0.86 kJ / m 2 , the foaming ratio is 23.1 times and the density is 0.064 g / cm 3 , the water contact angle is 108.3°, and the flame retardant grade is V-1.

[0222] Example 36

[0223] Refer to the method of Example 5 to prepare the starch-based composite foam board, the difference is that "15 parts by weight of polybutylene succinate and 15 parts by weight of polypropylene carbonate" is replaced by 30 parts by weight of polybutylene succinate.

[0224] Test the prepared starch-based composite foam board, and the results are: the rebound rate is 92%, the compression modulus is 8.26 MPa, and the impact strength is 0.80 kJ / m 2 , the foaming ratio is 21.3 times and the density is 0.070 g / cm 3 , the water contact angle is 103.1°, and the flame retardant grade is V-1.

[0225] Example 37

[0226] Prepare the starch-based composite foam board according to the method of Example 5, except that "15 parts by weight of polybutylene succinate and 15 parts by weight of polypropylene carbonate" is replaced with 30 parts by weight of polypropylene carbonate.

[0227] Test the prepared starch-based composite foam board, and the results are as follows: the rebound rate is 91%, the compression modulus is 7.93 MPa, and the impact strength is 0.87 kJ / m 2 , the foaming ratio is 22.8 times, and the density is 0.065 g / cm 3 , the water contact angle is 104.7°, and the flame retardant grade is V-2.

[0228] Comparative Example 1

[0229] Add 225 parts by weight of tap water and 75 parts by weight of 200-mesh corn starch to the reaction kettle, stir well at 60 °C for 60 min, the stirring speed is 150 rpm. After the starch is fully dissolved, lower the temperature to 55 °C, add 15 parts by weight of palmitic acid, and stir at the same rotation speed for 2 h for the modification reaction; then add 5 parts by weight of coconut fibers with a length of 2 mm and a diameter of 30 μm and 5 parts by weight of polyvinyl alcohol with a mesh number of 200 and a weight average molecular weight of 150,000, and continue to stir and react for 1 h at the same rotation speed and temperature; after the reaction is completed, cool to room temperature, wash 3 times with absolute ethanol, and carry out separation and purification in a high-speed centrifuge with the rotation speed set at 5000 rpm. Dry the precipitate and then crush it.

[0230] Transfer the above dried and crushed materials to a high-speed mixer, add 1 part by weight of antioxidant 626, 0.1 part by weight of chlorinated paraffin, 0.1 part by weight of 4000-mesh zirconium boride ceramic powder, 2 parts by weight of 3000-mesh talc powder, and 10 parts by weight of deionized water, mix well for 5 min, set the mixing temperature at 30 °C, and set the rotation speed at 600 rpm; apply 1 part by weight of silicone oil to the surface of the mold wall, then fill the above mixture into the mold, place it at 145 °C for foaming and expansion for 16 min, the pressure is 3 MPa, and dry and demold at 90 °C to obtain the starch-based composite foam board.

[0231] Test the obtained starch-based composite foam board, and the results are as follows: the rebound rate is 50%, the compression modulus is 2.31 MPa, and the impact strength is 0.31 kJ / m 2 , the foaming ratio is 7.2 times, and the density is 0.18 g / cm 3 , the water contact angle is 62.2°, and the foam board is a flammable material.

[0232] Comparative Example 2

[0233] Add 225 parts by weight of high-purity water, 75 parts by weight of corn starch with a mesh size of 200, and 5 parts by weight of coconut fibers with a length of 2.5 mm and a diameter of 30 μm into the reactor, mix and stir for 2 h, with the stirring speed set at 200 rpm and the temperature set at 65 °C; then add 5 parts by weight of polyvinyl alcohol with a mesh size of 200 and a weight-average molecular weight of 150,000, and continue to stir and react for 1 h at the same rotation speed and temperature; after the reaction is completed, cool to room temperature, wash 3 times with absolute ethanol, separate and purify in a high-speed centrifuge with the rotation speed set at 5000 rpm, and dry and crush the precipitate.

[0234] Transfer the above dried and crushed material to a high-speed mixer, add 1 part by weight of palmitic acid, 1 part by weight of antioxidant 1010, 0.1 part by weight of chlorinated paraffin, 0.1 part by weight of zirconium boride ceramic powder with a mesh size of 4100, 2 parts by weight of titanium dioxide with a mesh size of 3100, and 15 parts by weight of deionized water, mix well for 5 min, with the mixing temperature set at 40 °C and the rotation speed set at 600 rpm; apply 1 part by weight of magnesium stearate on the surface of the mold wall, then fill the above mixture into the mold, place it at 155 °C to foam and expand for 16 min under a pressure of 3 MPa, dry at 95 °C and then demold to obtain the starch-based composite foam board.

[0235] Test the starch-based composite foam board obtained above, and the results are as follows: the rebound rate is 48%, the compression modulus is 2.25 MPa, and the impact strength is 0.30 kJ / m 2 , the foaming ratio is 6.5 times, and the density is 0.20 g / cm 3 , the water contact angle is 69.5°, and the foam board is a flammable material.

[0236] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a starch-based composite foam material, comprising the following steps: a) mixing starch, environmentally friendly ionic liquid, water, biological enzyme and starch modifier to react, then mixing with plant fiber and toughening agent and continuing to react, removing the liquid phase to obtain a solid material; The environmentally friendly ionic liquid is one or more of choline acetate ionic liquid, choline dioxalate ionic liquid, choline arginine ionic liquid, choline proline ionic liquid, choline phosphate ionic liquid, choline acetate ionic liquid, choline alanine ionic liquid, choline glycine ionic liquid and choline butyrate ionic liquid; The biological enzyme is one or more of Candida lipase, immobilized lipase, porcine pancreatic lipase, horseradish peroxidase and α-amylase; The starch modifier is one or more of palmitic acid, n-butyl acetate, propylene glycol methyl ether acetate, stearic acid, succinic anhydride, lauric acid, rosin acid, sodium dodecylbenzene sulfonate and ε-caprolactone; The toughening agent is one or more of polyvinyl alcohol, polybutylene adipate / terephthalate, polybutylene succinate and polypropylene carbonate; b) mixing the solid material, antioxidant, flame retardant, heat resistant agent, nucleating agent and foaming agent, foaming and forming, and drying to obtain a starch-based composite foam material.

2. The preparation method according to claim 1, characterized in that: The starch is one or more of corn starch, rice starch, mung bean starch, pea starch, sweet potato starch, potato starch, chestnut starch and pumpkin starch; The plant fiber is one or more of coconut fiber, cotton fiber, reed fiber, straw fiber, ramie fiber, flax fiber, jute fiber, eucalyptus fiber, bamboo fiber, grass fiber and banana tree fiber.

3. The preparation method according to claim 1, characterized in that: The antioxidant is one or more of antioxidant DLTDP, antioxidant 626, antioxidant 1010, antioxidant 1075, antioxidant 2246 and tea polyphenols; The flame retardant is one or more of chlorinated paraffin, antimony trioxide, aluminum hydroxide and magnesium hydroxide; The heat-resistant agent is ceramic powder; The nucleating agent is one or more of silicon dioxide, talc, titanium dioxide, calcium carbonate, zinc oxide and montmorillonite; The foaming agent is water.

4. The preparation method according to claim 1, characterized in that: Based on 100 parts by weight of the starch, the total amount of the environmentally friendly ionic liquid and water is 300-500 parts by weight, and the mass ratio of the environmentally friendly ionic liquid to water is 1:(1-3); the amount of the biological enzyme is 5-8 parts by weight; the amount of the starch modifier is 15-20 parts by weight; the amount of the plant fiber is 5-20 parts by weight; the amount of the toughening agent is 5-30 parts by weight; the amount of the antioxidant is 1-3 parts by weight; the amount of the flame retardant is 0.1-2 parts by weight; the amount of the heat-resistant agent is 0.1-2 parts by weight; the amount of the nucleating agent is 2-10 parts by weight; and the amount of the foaming agent is 5-15 parts by weight.

5. The preparation method according to claim 1, characterized in that: The temperature of the mixed reaction is 55-65° C.; the time of the mixed reaction is 2-4 hours; the temperature of the continued reaction is 55-65° C.; the time of the continued reaction is 1-2 hours.

6. The preparation method according to claim 1, characterized in that: The temperature of the foaming molding is 145-165° C.; the pressure of the foaming molding is 3-5 MPa; and the time of the foaming molding is 16-20 min.

7. The preparation method according to claim 1, characterized in that: In step b), a waterproofing agent is also added during the mixing process; the waterproofing agent is one or more of acrylate copolymer, hexadecanoic acid, silicone waterproofing agent, dispersed rosin glue and paraffin.

8. The preparation method according to claim 1, characterized in that: The foaming molding is carried out in a mold pre-coated with a release agent; the release agent is one or more of silicone oil, zinc stearate, magnesium stearate and liquid paraffin.

9. A starch-based composite foam material, characterized in that: It is prepared according to the preparation method according to any one of claims 1 to 8.

10. A starch-based composite foam board, characterized in that: The material is the starch-based composite foam material described in claim 9.