A degradable starch foaming buffer material and preparation method thereof

Abstract

The present invention belongs to the field of foaming materials, and in particular relates to a degradable starch foaming cushioning material and a preparation method thereof. The preparation method provided by the present invention comprises the following steps: a) mixing starch, ionic liquid, water and a starch modifier for reaction, then mixing with plant fiber and biodegradable resin, removing the liquid phase, and obtaining a solid material; b) melt-blending the solid material, foaming agent and nucleating agent and foaming molding to obtain a degradable starch foaming cushioning material. The present invention uses ionic liquid and water in appropriate proportions as plasticizers, catalysts and compatibilizers, and promotes the swelling, plasticization and phase transition process of starch through the reaction between the ionic liquid and the starch end group, thereby improving the degree of substitution of the modified starch and the compatibility of starch with plant fiber and biodegradable resin, improving the foaming ratio of starch, and increasing the resilience, so that the starch foaming cushioning material finally prepared has good comprehensive mechanical properties.

Description

Technical Field

[0001] The invention belongs to the field of foaming materials, and in particular relates to a degradable starch foaming buffer material and a preparation method thereof. Background Art

[0002] In recent years, the issue of non-degradable plastic waste has become an urgent challenge, and the search for alternative, environmentally friendly polymers has become a key research focus for researchers worldwide. Currently, polyethylene products are still the primary form of cushioning packaging, and the amount of disposable cushioning packaging discarded has skyrocketed year by year. Despite the emergence of biodegradable products such as polylactic acid and polybutylene adipate / terephthalate, their high prices have limited their widespread application.

[0003] Starch, a naturally occurring, abundant, and inexpensive polymer, boasts excellent processability and can be made into a variety of finished products. However, starch also suffers from drawbacks such as high brittleness, poor resilience, and low expansion ratio. Improving the expansion ratio and mechanical properties of starch-based foam cushioning materials is an urgent challenge in this field. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a degradable starch foaming buffer material and a preparation method thereof. The foaming material prepared by the present invention has a high foaming ratio and good comprehensive mechanical properties.

[0005] The present invention provides a method for preparing a degradable starch foaming buffer material, comprising the following steps:

[0006] a) mixing starch, ionic liquid, water and starch modifier for reaction, then mixing with plant fiber and biodegradable resin, removing the liquid phase to obtain a solid material;

[0007] b) melt-blending the solid material, the foaming agent and the nucleating agent and then foaming and molding the mixture to obtain a degradable starch foaming cushioning material.

[0008] Preferably, the ionic liquid is one or more of toluenesulfonic acid ionic liquid, 1-butyl-3-methylimidazolium chloride ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid, 1-butyl-3-methylimidazolium dicyanamide ionic liquid, 1,3-dimethylimidazolium methyl phosphite ionic liquid, 1-octyl-3-methyl acetate ionic liquid, 1-hydroxypropyl-3-methylimidazolium acetate ionic liquid, 1-octyl-3-methylnitrate ionic liquid and 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid.

[0009] Preferably, the starch modifier is one or more of maleic anhydride, succinic anhydride, vinyl acetate, methyl palmitate, lauric acid and stearic acid.

[0010] Preferably, the starch is one or more of corn amylose, waxy corn amylopectin, wheat starch, barley starch, rice starch, potato starch, sweet potato starch, yams starch and tapioca starch;

[0011] 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;

[0012] The biodegradable resin is one or more of polybutylene adipate / terephthalate, polyvinyl alcohol, polybutylene succinate and polypropylene carbonate.

[0013] Preferably, the foaming agent is one or more of tap water, distilled water, deionized water, high-purity water and reverse osmosis water;

[0014] The nucleating agent is one or more of silicon dioxide, talc, titanium dioxide, calcium carbonate, zinc oxide and montmorillonite.

[0015] Preferably, based on 100 parts by weight of the starch, the total amount of the ionic liquid and water is 400 to 500 parts by weight, and the mass ratio of the ionic liquid to water is (1 to 2):3; the amount of the starch modifier is 10 to 20 parts by weight; the amount of the plant fiber is 5 to 20 parts by weight; the amount of the biodegradable resin is 5 to 20 parts by weight; the amount of the foaming agent is 5 to 15 parts by weight; and the amount of the nucleating agent is 2 to 10 parts by weight.

[0016] Preferably, the temperature of the mixing reaction is 60-80° C.; and the time of the mixing reaction is 2-4 hours.

[0017] Preferably, a waterproofing agent is also added during the melt blending process.

[0018] Preferably, the waterproofing agent is one or more of acrylate copolymer, hexadecanoic acid, silicone waterproofing agent, dispersed rosin glue and paraffin.

[0019] The present invention also provides a degradable starch foaming buffer material prepared by the preparation method described in the above technical solution.

[0020] Compared with the prior art, the present invention provides a degradable starch foaming cushioning material and a preparation method thereof. The preparation method provided by the present invention comprises the following steps: a) mixing starch, ionic liquid, water and starch modifier for reaction, then mixing with plant fiber and biodegradable resin, removing the liquid phase to obtain a solid material; b) melt-blending the solid material, foaming agent and nucleating agent and foaming and molding to obtain a degradable starch foaming cushioning material. The present invention uses ionic liquid and water in appropriate proportions as plasticizers, catalysts and compatibilizers, and promotes the swelling, plasticization and phase transition process of starch through the reaction between ionic liquid and starch end groups, thereby increasing the degree of substitution of modified starch and the compatibility of starch with plant fiber and biodegradable resin, improving the foaming ratio of starch, and increasing resilience, so that the starch foaming cushioning material finally prepared has good comprehensive mechanical properties. DETAILED DESCRIPTION

[0021] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0022] The present invention provides a method for preparing a degradable starch foaming buffer material, comprising the following steps:

[0023] a) mixing starch, ionic liquid, water and starch modifier for reaction, then mixing with plant fiber and biodegradable resin, removing the liquid phase to obtain a solid material;

[0024] b) melt-blending the solid material, the foaming agent and the nucleating agent and then foaming and molding the mixture to obtain a degradable starch foaming cushioning material.

[0025] In the preparation method provided by the present invention, the starch is preferably one or more of corn amylose, glutinous corn amylopectin, wheat starch, barley starch, rice starch, potato starch, sweet potato starch, yams and cassava starch; the mesh size of the starch is preferably 200-400 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.

[0026] In one embodiment provided by the present invention, the starch is wheat starch and barley starch; the mass ratio of the wheat starch to the barley starch is preferably 1:(0.5-2), more preferably 1:1.

[0027] In one embodiment provided by the present invention, the starch is sweet potato starch, yams starch and tapioca starch in a mass ratio of preferably (1-5):(1-5):4, more preferably 3:3:4.

[0028] In one embodiment provided by the present invention, the starch is waxy corn amylopectin and potato starch, and the mass ratio of the waxy corn amylopectin to potato starch is preferably 1:(0.5-2), more preferably 1:1.

[0029] In the preparation method provided by the present invention, the ionic liquid is preferably one or more of toluenesulfonic acid ionic liquid, 1-butyl-3-methylimidazolium chloride ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid, 1-butyl-3-methylimidazolium dicyanamide ionic liquid, 1,3-dimethylimidazolium methyl phosphite ionic liquid, 1-octyl-3-methyl acetate ionic liquid, 1-hydroxypropyl-3-methylimidazolium acetate ionic liquid, 1-octyl-3-methylnitrate ionic liquid and 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid.

[0030] In one embodiment provided by the present invention, the ionic liquid is 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid and 1-butyl-3-methylimidazolium dicyanamide ionic liquid; the mass ratio of the 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid and the 1-butyl-3-methylimidazolium dicyanamide ionic liquid is preferably 1:(0.5-2), more preferably 1:1.

[0031] In one embodiment provided by the present invention, the ionic liquid is a 1-butyl-3-methylimidazolium dicyanamide ionic liquid and a 1,3-dimethylimidazolium methyl phosphite ionic liquid; the mass ratio of the 1-butyl-3-methylimidazolium dicyanamide ionic liquid and the 1,3-dimethylimidazolium methyl phosphite ionic liquid is preferably 1:(0.5-2), more preferably 1:1.

[0032] In one embodiment provided by the present invention, the ionic liquid is 1-hydroxypropyl-3-methylimidazolium acetate ionic liquid, 1-octyl-3-methylnitrate ionic liquid and 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid; the mass ratio of the 1-hydroxypropyl-3-methylimidazolium acetate ionic liquid, 1-octyl-3-methylnitrate ionic liquid and 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid is preferably 6:(5-10):(5-10), more preferably 6:7:7.

[0033] 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, preferably tap water.

[0034] In the preparation method provided by the present invention, based on 100 parts by weight of the starch, the total amount of the ionic liquid and water is preferably 400 to 500 parts by weight, specifically 405 parts by weight, 410 parts by weight, 415 parts by weight, 420 parts by weight, 425 parts by weight, 430 parts by weight, 435 parts by weight, 440 parts by weight, 445 parts by weight, 450 parts by weight, 455 parts by weight, 460 parts by weight, 465 parts by weight, 470 parts by weight, 475 parts by weight, 480 parts by weight, 485 parts by weight, 490 parts by weight, 495 parts by weight or 500 parts by weight; the mass ratio of the ionic liquid to water is preferably (1-2):3, specifically 1:3, 1.05:3, 1.1:3, 1.15:3, 1.2:3, 1.25:3, 1.3:3, 1.35:3, 1.4:3, 1.45:3, 1.5:3, 1.55:3, 1.6:3, 1.65:3, 1.7:3, 1.75:3, 1.8:3, 1.85:3, 1.9:3, 1.95:3 or 2:3.

[0035] In the preparation method provided by the present invention, the starch modifier is preferably one or more of maleic anhydride, succinic anhydride, vinyl acetate, methyl palmitate, lauric acid and stearic acid.

[0036] In one embodiment provided by the present invention, the starch modifier is succinic anhydride and stearic acid; the mass ratio of succinic anhydride to stearic acid is preferably 1:(0.5-2), more preferably 1:1.

[0037] In one embodiment provided by the present invention, the starch modifiers are stearic acid and methyl palmitate; the mass ratio of stearic acid to methyl palmitate is preferably 1:(0.5-2), more preferably 1:1.

[0038] 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 10 to 20 parts by weight, specifically 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.

[0039] In the preparation method provided by the present invention, the stirring speed of the mixing reaction is preferably 200-400 rpm, specifically 200 rpm, 250 rpm, 300 rpm, 350 rpm or 400 rpm; the temperature of the mixing reaction is preferably 60-80°C, specifically 60°C, 65°C, 70°C, 75°C or 80°C; the time of the mixing reaction is preferably 2-4h, specifically 2h, 2.5h, 3h, 3.5h or 4h.

[0040] 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 m, 3.3mm, 3.4mm, 3.5mm, 3.6mm, 3.7mm, 3.8mm, 3.9mm or 4mm; the diameter of the plant fiber is preferably 30-50μm, specifically 30μm, 31μm, 32μm, 33μm, 34μm, 35μm, 36μm, 37μm, 38μm, 39μm, 40μm, 41μm, 42μm, 43μm, 44μm, 45μm, 46μm, 47μm, 48μm, 49μm or 50μm.

[0041] In one embodiment provided by the present invention, the plant fibers are eucalyptus fibers and straw fibers; the mass ratio of the eucalyptus fibers to the straw fibers is preferably 1:(0.5-2), more preferably 1:1.

[0042] In one embodiment provided by the present invention, the plant fibers are flax fibers and reed fibers; the mass ratio of the flax fibers to the reed fibers is preferably 1:(0.5-2), more preferably 1:1.

[0043] In one embodiment provided by the present invention, the plant fibers are jute fibers and cotton fibers; the mass ratio of the jute fibers to the cotton fibers is preferably 1:(0.5-2), more preferably 1:1.

[0044] 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.

[0045] In the preparation method provided by the present invention, the biodegradable resin is preferably one or more of polybutylene adipate / terephthalate, polyvinyl alcohol, 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 weight average molecular weight of the biodegradable resin is preferably 100,000 to 400,000, specifically 100,000, 110,000, 120,000, 130,000, 140,000, 150,000, 160,000, 170,000, 180,000, The mesh number of the biodegradable resin is preferably 200-400 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.

[0046] In one embodiment provided by the present invention, the biodegradable resin is polyvinyl alcohol and polybutylene succinate; the mass ratio of the polyvinyl alcohol to polybutylene succinate is preferably 8:(5-15), more preferably 8:9.

[0047] In one embodiment provided by the present invention, the biodegradable resin is polybutylene adipate / terephthalate and polybutylene succinate; the mass ratio of polybutylene adipate / terephthalate and polybutylene succinate is preferably 1:(0.5-2), more preferably 1:1.

[0048] In the preparation method provided by the present invention, based on 100 parts by weight of the starch, the amount of the biodegradable resin is 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.

[0049] In the preparation method provided by the present invention, the rotation speed of the mixing with the plant fiber and the biodegradable resin is preferably 200 to 400 rpm, specifically 200 rpm, 250 rpm, 300 rpm, 350 rpm or 400 rpm; the mixing time is preferably 40 to 60 min, specifically 40 min, 45 min, 50 min, 55 min or 60 min.

[0050] In the preparation method provided by the present invention, the liquid phase is preferably removed by centrifugation; the rotation speed of the centrifugation is preferably 5000 to 10000 rpm, specifically 5000 rpm, 6000 rpm, 7000 rpm, 8000 rpm, 9000 rpm, or 10000 rpm. In the present invention, after the centrifugation, the obtained solid material is preferably washed and dried; the washing agent is preferably anhydrous ethanol; the drying temperature is preferably 60 to 80°C, specifically 60°C, 65°C, 70°C, 75°C, or 80°C.

[0051] In the preparation method provided by the present invention, after obtaining the solid material, it is preferably crushed into powder.

[0052] 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.

[0053] In the preparation method provided by the present invention, based on 100 parts by weight of the starch, the amount of the foaming agent is preferably 5 to 15 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 or 15 parts by weight.

[0054] In the preparation method provided by the present invention, the nucleating agent is preferably one or more of silicon dioxide, talc, titanium dioxide, calcium carbonate, zinc oxide and montmorillonite; the particle size of the nucleating agent is preferably 50 to 200 nm, specifically 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm or 200 nm.

[0055] In one embodiment provided by the present invention, the nucleating agent is titanium dioxide and calcium carbonate; the mass ratio of the titanium dioxide and calcium carbonate is preferably (1-5):4, more preferably 3:4.

[0056] In one embodiment provided by the present invention, the nucleating agent is calcium carbonate and zinc oxide; the mass ratio of the calcium carbonate to zinc oxide is preferably 1:(0.5-2), more preferably 1:1.

[0057] 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 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.

[0058] In the preparation method provided by the present invention, a waterproofing agent is preferably further added during the melt blending process; the waterproofing agent is preferably one or more of an acrylate copolymer, hexadecanoic acid, a silicone waterproofing agent, a dispersed rosin glue and paraffin wax; the comonomers 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 to 80,000, specifically 60,000, 65,000, 70,000, 75,000 or 80,000; the active ingredient in the silicone waterproofing agent is preferably potassium methyl silicate.

[0059] In one embodiment provided by the present invention, the waterproofing agent is a copolymer of hexadecanoic acid and acrylate; the mass ratio of the hexadecanoic acid and acrylate copolymer is preferably 1:(0.5-2), more preferably 1:1.

[0060] In one embodiment provided by the present invention, the waterproofing agent is dispersed rosin glue and paraffin wax; the mass ratio of the dispersed rosin glue and paraffin wax is preferably 1:(0.5-2), more preferably 1:1.

[0061] In the preparation method provided by the present invention, based on 100 parts by weight of the starch, the amount of the waterproofing agent is preferably 0 to 5 parts by weight, specifically 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.

[0062] In the preparation method provided by the present invention, the materials involved in the melt blending are preferably premixed uniformly before being melt blended. The stirring speed of the premixing is preferably 500 to 700 rpm, specifically 500 rpm, 550 rpm, 600 rpm, 650 rpm, or 700 rpm; the premixing time is preferably 10 to 30 minutes, specifically 10 minutes, 15 minutes, 20 minutes, 25 minutes, or 30 minutes.

[0063] In the preparation method provided by the present invention, the melt blending is preferably carried out in an extruder, including but not limited to a single-screw or twin-screw extruder; the temperature of the blending zone of the extruder is preferably set to 160-180°C, specifically 160°C, 165°C, 170°C, 175°C or 180°C; the die head temperature of the extruder is preferably set to 140-160°C, specifically 140°C, 145°C, 150°C, 155°C or 160°C; the screw speed of the extruder is preferably 150-220 rpm, specifically 140-145°C, 150-155°C or 160°C. The speed is 150 rpm, 155 rpm, 160 rpm, 165 rpm, 170 rpm, 175 rpm, 180 rpm, 185 rpm, 190 rpm, 195 rpm, 200 rpm, 205 rpm, 210 rpm, 215 rpm or 220 rpm; the die head diameter of the extruder is preferably 1-3 mm, specifically 1 mm, 1.5 mm, 2 mm, 2.5 mm or 3 mm.

[0064] In the preparation method provided by the present invention, when an extruder is used for the melt blending, the melt blend is extruded from the die head of the extruder and then foamed to obtain a degradable starch foaming cushioning material.

[0065] The present invention also provides a degradable starch foaming buffer material prepared according to the preparation method described in the above technical solution.

[0066] The present invention optimizes and improves the preparation method of starch foaming buffer material to obtain a foaming material with a high foaming ratio and good comprehensive mechanical properties. Specifically, the key points of the technical solution of the present invention are as follows: 1) the ionic liquid reacts synergistically with water and starch to promote the swelling, gelatinization and plasticization processes of the starch, thereby improving the mechanical properties of the starch; 2) the ionic liquid and water synergistically promote the reaction between starch and the modifier, increase the degree of substitution of the modifier, improve the foaming ratio and rebound resilience of the starch, and improve the comprehensive performance of the modified starch; 3) the ionic liquid and water synergistically improve the compatibility of starch with biodegradable resin and plant cellulose, thereby increasing the dispersibility of the two and enhancing the interfacial bonding strength.

[0067] The technical solution provided by the present invention includes at least the following advantages: 1) the method provided by the present invention is used to prepare a degradable starch foaming cushioning material, which improves the foaming ratio and rebound performance of the material and can be widely used in cushioning packaging materials; 2) the degradable starch foaming cushioning material prepared according to the method of the present invention has a high degree of modification, high interfacial bonding strength, excellent comprehensive mechanical properties, is completely biodegradable, and has high product application value; 3) the preparation method provided by the present invention uses ionic liquids and water instead of traditional plasticizers and compatibilizers, which simplifies the preparation scheme, improves the reactivity of starch, can significantly reduce production consumption, and improves production efficiency; 4) the preparation method provided by the present invention can use water as a foaming agent, is safe and environmentally friendly, and the entire process is pollution-free.

[0068] For the sake of clarity, the following examples and comparative examples are provided for detailed description. In the following examples and comparative examples of the present invention, the specific evaluation methods for various properties are as follows:

[0069] (1) Rebound resilience test:

[0070] Use a high-precision thickness gauge to measure the diameter of the foamed beads. Then, clamp the foamed beads with the thickness gauge and compress them to 1 / 2 of the diameter. Release the gauge after 10 seconds and measure the diameter of the foamed beads again after 1 minute. Calculate the rebound resilience of the foamed beads using the formula. Take the average of ten test values: Rebound resilience = (diameter after rebound - 1 / 2 diameter before compression) ÷ 1 / 2 diameter before compression × 100%.

[0071] (2) Compression modulus determination:

[0072] Cylindrical starch foam was cut into samples of a certain height and their diameter and height were measured. The compression rate was 5 mm / min and the test was performed using a universal testing machine. The compression modulus of the starch foam was calculated from the initial linear portion of the compression stress-strain curve and the average value of the five samples was taken.

[0073] (3) Impact strength determination:

[0074] Impact strength was measured according to GB / T 1843-2008, "Plastics - Determination of Izod Beam Impact Strength," with the kinetic energy of the impact pendulum being 3.25 J. Five groups of samples were tested, and the final result was the average of the five groups.

[0075] (4) Foaming ratio determination:

[0076] The expansion ratio of starch foam is the density of the foam matrix divided by the density of the starch foam. The density of the foam is calculated from mass and volume. The volume is determined by the displacement method. The density of the foam matrix is ​​measured using a similar method. The calculated density value is then substituted into the average of 10 samples.

[0077] (5) Density determination:

[0078] Apparent density was tested according to GB / T 6343-2009, "Determination of apparent density of cellular plastics and rubber." The length and diameter of the sample were measured, and the total volume was calculated. To minimize experimental error, five groups of samples were collected, and the final result was the average of the five groups. Density = sample mass divided by sample volume.

[0079] (6) Water contact angle measurement:

[0080] After drying, the foam was cooled with liquid nitrogen and then fractured. The cut sections were cut and fixed to a glass slide with double-sided tape. The hydrophilicity of the samples was measured using a contact angle tester. Each sample was tested three times, and the results were averaged.

[0081] Example 1

[0082] First, 300 parts by weight of tap water and 100 parts by weight of toluenesulfonic acid ionic liquid are prepared into a mixed solution, and then the mixed solution and 100 parts by weight of corn amylose with a mesh size of 200 are placed in a reactor, and 10 parts by weight of maleic anhydride are placed, and the mixture is fully mixed and reacted for 2 hours, the mixing temperature is set to 60°C, and the speed is set to 200 rpm; then, 5 parts by weight of coconut fiber with a length of 2 mm and a diameter of 30 μm and 5 parts by weight of polybutylene adipate / terephthalate with a mesh size of 200 mesh (weight-average molecular weight of 100,000, wherein the molar ratio of aliphatic polyester (BA) repeating units to aromatic polyester (BT) repeating units is 60:40) are added, and the mixture is mixed at the same speed for 40 minutes; then, the mixture is separated in a high-speed centrifuge to remove the ionic liquid and water, etc., the speed is set to 5000 rpm, and then repeatedly washed and centrifuged with anhydrous ethanol three times, and the obtained precipitate is dried at 60°C.

[0083] The dried material was added to a high-speed mixer, and 5 parts by weight of tap water as a foaming agent and 2 parts by weight of silicon dioxide with a particle size of 50 nm were added at the same time. The mixture was stirred at room temperature for 10 min at a stirring speed of 500 rpm. After thorough mixing, the mixture was melt-blended in a single-screw extruder and extruded for foaming. The temperature of the blending zone was set to 160°C, the die extrusion temperature was set to 140°C, the screw speed was set to 150 rpm, and the die extrusion diameter was 1 mm.

[0084] The foamed material obtained by extrusion was tested, and the results showed that the rebound rate of the foamed particles was 68%, the compression modulus was 4.81 MPa, and the impact strength was 0.50 kJ / m 2 The foaming ratio is 9.6 times and the density is 0.144g / cm 3 , the water contact angle is 63.9°.

[0085] Example 2

[0086] First, 300 parts by weight of tap water and 125 parts by weight of 1-butyl-3-methylimidazolium chloride ionic liquid are prepared into a mixed solution. The mixed solution and 100 parts by weight of wheat starch with a mesh size of 250 mesh are then placed in a reactor, and 12.5 parts by weight of succinic anhydride are added. The mixture is fully mixed and reacted for 2.5 hours. The mixing temperature is set to 65°C and the rotation speed is set to 250 rpm. Then, 9 parts by weight of jute fiber with a length of 2.5 mm and a diameter of 35 μm and 9 parts by weight of polyvinyl alcohol with a mesh size of 250 mesh (weight-average molecular weight of 180,000) are added, and the mixture is mixed at the same rotation speed for 45 minutes. The mixture is then separated in a high-speed centrifuge to remove the ionic liquid and water. The rotation speed is set to 6000 rpm. The mixture is then repeatedly washed and centrifuged three times with anhydrous ethanol, and the obtained precipitate is dried at 65°C.

[0087] The above-mentioned dried material was crushed and added to a high-speed mixer. At the same time, 7.5 parts by weight of high-purity water was added as a foaming agent, 4 parts by weight of talc with a particle size of 80 nm, and 1.5 parts by weight of a silicone waterproofing agent (brand: YR-Y18, active ingredient: potassium methyl silicate, manufacturer: Nanjing Yingrun New Material Technology Co., Ltd.) were added. The mixture was stirred at room temperature for 15 minutes at a stirring speed of 550 rpm. After sufficient mixing, the mixture was melt-blended in a twin-screw extruder and extruded for foaming. The temperature in the blending zone was set to 165°C, the die extrusion temperature was set to 145°C, the screw speed was set to 170 rpm, and the die extrusion diameter was 1.5 mm.

[0088] The foamed material obtained by extrusion was tested, and the results showed that the rebound rate of the foamed particles was 74%, the compression modulus was 5.66 MPa, and the impact strength was 0.59 kJ / m 2 The foaming ratio is 12.5 times and the density is 0.114g / cm 3 , the water contact angle is 86.5°.

[0089] Example 3

[0090] First, 300 parts by weight of tap water, 75 parts by weight of 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid, and 75 parts by weight of 1-butyl-3-methylimidazolium dicyanamide ionic liquid are prepared into a mixed solution. The mixed solution is then placed in a reactor with 50 parts by weight of wheat starch and 50 parts by weight of barley starch with a mesh size of 300 mesh, and 15 parts by weight of vinyl acetate is placed. The mixture is fully mixed and reacted for 3 hours, the mixing temperature is set to 70°C, and the speed is set to 300 rpm. Then, 6 parts by weight of eucalyptus fiber with a length of 3 mm and a diameter of 40 μm and 6 parts by weight of straw fiber, as well as 13 parts by weight of polybutylene succinate (weight-average molecular weight of 260,000) with a mesh size of 300 mesh are added, and the mixture is mixed at the same speed for 50 minutes. The mixture is then separated in a high-speed centrifuge to remove the ionic liquid and water, etc. The speed is set to 7000 rpm, and then the mixture is repeatedly washed and centrifuged three times with anhydrous ethanol. The obtained precipitate is dried at 70°C.

[0091] The dried material was crushed and added to a high-speed mixer. 10 parts by weight of distilled water as a foaming agent, 6 parts by weight of montmorillonite with a particle size of 120 nm, and 3 parts by weight of dispersed rosin size were added at the same time. The mixture was stirred at room temperature for 20 min at a stirring speed of 600 rpm. After thorough mixing, the mixture was melt-blended in a twin-screw extruder and extruded for foaming. The temperature in the blending zone was set to 170°C, the die extrusion temperature was set to 150°C, the screw speed was set to 180 rpm, and the die extrusion diameter was 2 mm.

[0092] The foamed material obtained by extrusion was tested, and the results showed that the rebound rate of the foamed particles was 85%, the compression modulus was 6.98 MPa, and the impact strength was 0.67 kJ / m 2 The foaming ratio is 18.5 times and the density is 0.080g / cm 3 , the water contact angle is 96.8°.

[0093] Example 4

[0094] First, 300 parts by weight of tap water, 90 parts by weight of 1-butyl-3-methylimidazolium dicyanamide ionic liquid and 90 parts by weight of 1,3-dimethylimidazolium methyl phosphite ionic liquid were prepared into a mixed solution. Then, the mixed solution and 30 parts by weight of sweet potato starch, 30 parts by weight of sweet potato starch and 40 parts by weight of cassava starch with a mesh size of 350 were placed in a reactor, and 9 parts by weight of succinic anhydride and 9 parts by weight of stearic acid were placed. The mixture was fully mixed and reacted for 3.5 hours. The mixing temperature was set to 75°C and the speed was set to 350 rpm. ; Then, 8 parts by weight of flax fiber with a length of 3.5 mm and a diameter of 45 μm and 8 parts by weight of reed fiber, as well as 8 parts by weight of polyvinyl alcohol (weight-average molecular weight of 320,000) and 9 parts by weight of polybutylene succinate (weight-average molecular weight of 320,000) with a mesh size of 350 were added and mixed at the same speed for 55 minutes; then the mixture was separated in a high-speed centrifuge to remove ionic liquid and water, etc., the speed was set to 9000 rpm, and then repeatedly washed and centrifuged with anhydrous ethanol three times, and the obtained precipitate was dried at 75°C.

[0095] The above-mentioned dried material was crushed and added to a high-speed mixer, and 12.5 parts by weight of high-purity water was added as a blowing agent, 3 parts by weight of titanium dioxide and 4 parts by weight of calcium carbonate with a particle size of 160 nm, as well as 2 parts by weight of hexadecanoic acid and 2 parts by weight of an acrylate copolymer (weight-average molecular weight of 70,000, prepared by copolymerization of butyl acrylate (BA) and methyl methacrylate (MMA), with a mass ratio of BA to MMA of 3:2) were added. The mixture was stirred at room temperature for 25 minutes at a stirring speed of 650 rev / min. After sufficient mixing, the mixture was melt-blended in a twin-screw extruder and extruded for foaming. The temperature in the blending zone was set to 175°C, the die extrusion temperature was set to 155°C, the screw speed was set to 200 rev / min, and the die extrusion diameter was 2.5 mm.

[0096] The foamed material obtained by extrusion was tested, and the results showed that the rebound rate of the foamed particles was 91%, the compression modulus was 7.56 MPa, and the impact strength was 0.75 kJ / m 2 The foaming ratio is 24.6 times and the density is 0.061g / cm 3 , the water contact angle is 103.9°.

[0097] Example 5

[0098] First, 300 parts by weight of tap water, 60 parts by weight of 1-hydroxypropyl-3-methylimidazolium acetate ionic liquid, 70 parts by weight of 1-octyl-3-methylnitrate ionic liquid and 70 parts by weight of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid were prepared into a mixed solution, and then the mixed solution and 100 parts by weight of 400-mesh 50 parts by weight of waxy corn amylopectin and 50 parts by weight of potato starch were placed in a reactor, 10 parts by weight of stearic acid and 10 parts by weight of methyl palmitate were placed, and the mixture was fully mixed and reacted for 4 hours. The mixing temperature was set to 80°C and the speed was set to 400 rpm. Then, a 4 mm long and 4 mm diameter cellulose ester was added. Ten parts by weight of jute fiber (50 μm) and 10 parts by weight of cotton fiber, as well as 10 parts by weight of polybutylene adipate / terephthalate (weight-average molecular weight of 400,000, wherein the molar ratio of aliphatic polyester (BA) repeating units to aromatic polyester (BT) repeating units is 40:60) with a mesh size of 400 mesh, and 10 parts by weight of polybutylene succinate (weight-average molecular weight of 400,000) are mixed at the same speed for 60 minutes; the mixture is then separated in a high-speed centrifuge to remove ionic liquid and water, etc., with the speed set to 10,000 rpm, and then repeatedly washed and centrifuged three times with anhydrous ethanol, and the obtained precipitate is dried at 80°C.

[0099] The dried product was crushed and added to a high-speed mixer. 15 parts by weight of deionized water as a foaming agent, 5 parts by weight of calcium carbonate with a particle size of 200 nm and 5 parts by weight of zinc oxide, as well as 2.5 parts by weight of dispersed rosin glue and 2.5 parts by weight of paraffin were also added. The mixture was stirred at room temperature for 30 min at a stirring speed of 700 rpm. After thorough mixing, the mixture was melt-blended in a twin-screw extruder and extruded for foaming. The temperature in the blending zone was set to 180° C., the die extrusion temperature was set to 160° C., the screw speed was set to 220 rpm, and the die extrusion diameter was 3 mm.

[0100] The foamed material obtained by extrusion was tested, and the results showed that the rebound rate of the foamed particles was 88%, the compression modulus was 7.41 MPa, and the impact strength was 0.87 kJ / m 2 The foaming ratio is 22.5 times and the density is 0.066g / cm 3 , the water contact angle is 101.3°.

[0101] Example 6

[0102] A foaming material was prepared according to the method of Example 3, except that “75 parts by weight of 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid and 75 parts by weight of 1-butyl-3-methylimidazolium dicyanamide ionic liquid” were replaced with 150 parts by weight of 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid.

[0103] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 83%, the compression modulus was 6.66 MPa, and the impact strength was 0.68 kJ / m 2 The foaming ratio is 16.4 times and the density is 0.089g / cm 3 , the water contact angle is 95.3°.

[0104] Example 7

[0105] A foaming material was prepared according to the method of Example 3, except that “75 parts by weight of 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid and 75 parts by weight of 1-butyl-3-methylimidazolium dicyanamide ionic liquid” were replaced with 150 parts by weight of 1-butyl-3-methylimidazolium dicyanamide ionic liquid.

[0106] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 84%, the compression modulus was 6.84 MPa, and the impact strength was 0.65 kJ / m 2 The foaming ratio is 17.5 times and the density is 0.083g / cm 3 , the water contact angle is 96.8°.

[0107] Example 8

[0108] A foaming material was prepared according to the method of Example 3, except that “50 parts by weight of wheat starch and 50 parts by weight of barley starch” were replaced by 100 parts by weight of wheat starch.

[0109] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 84%, the compression modulus was 6.49 MPa, and the impact strength was 0.62 kJ / m 2 The foaming ratio is 16.2 times and the density is 0.081g / cm 3 , the water contact angle is 93.1°.

[0110] Example 9

[0111] A foaming material was prepared according to the method of Example 3, except that “50 parts by weight of wheat starch and 50 parts by weight of barley starch” were replaced by 100 parts by weight of barley starch.

[0112] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 85%, the compression modulus was 6.94 MPa, and the impact strength was 0.67 kJ / m 2 The foaming ratio is 18.4 times and the density is 0.079g / cm 3 , the water contact angle is 96.7°.

[0113] Example 10

[0114] The foaming material was prepared by referring to the method of Example 3, except that “6 parts by weight of eucalyptus fiber and 6 parts by weight of straw fiber” were replaced by 12 parts by weight of eucalyptus fiber.

[0115] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 86%, the compression modulus was 7.02 MPa, and the impact strength was 0.71 kJ / m 2 The foaming ratio is 17.9 times and the density is 0.082g / cm 3 , the water contact angle is 97.2°.

[0116] Example 11

[0117] A foaming material was prepared by referring to the method of Example 3, except that “6 parts by weight of eucalyptus fiber and 6 parts by weight of straw fiber” were replaced by 12 parts by weight of straw fiber.

[0118] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 83%, the compression modulus was 6.31 MPa, and the impact strength was 0.63 kJ / m 2 The foaming ratio is 18.9 times and the density is 0.078g / cm 3 , the water contact angle is 95.9°.

[0119] Example 12

[0120] A foaming material was prepared according to the method of Example 4, except that “90 parts by weight of 1-butyl-3-methylimidazolium dicyanamide ionic liquid and 90 parts by weight of 1,3-dimethylimidazolium methyl phosphite ionic liquid” were replaced with 180 parts by weight of 1-butyl-3-methylimidazolium dicyanamide ionic liquid.

[0121] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 90%, the compression modulus was 7.50 MPa, and the impact strength was 0.76 kJ / m 2 The foaming ratio is 24.1 times and the density is 0.060g / cm 3 , the water contact angle is 103.5°.

[0122] Example 13

[0123] A foaming material was prepared according to the method of Example 4, except that “90 parts by weight of 1-butyl-3-methylimidazolium dicyanamide ionic liquid and 90 parts by weight of 1,3-dimethylimidazolium methyl phosphite ionic liquid” were replaced with 180 parts by weight of 1,3-dimethylimidazolium methyl phosphite ionic liquid.

[0124] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 91%, the compression modulus was 7.41 MPa, and the impact strength was 0.72 kJ / m 2 The foaming ratio is 24.8 times and the density is 0.059g / cm 3 , the water contact angle is 102.9°.

[0125] Example 14

[0126] A foaming material was prepared by referring to the method of Example 4, except that “30 parts by weight of sweet potato starch, 30 parts by weight of yams and 40 parts by weight of cassava starch” were replaced by 100 parts by weight of sweet potato starch.

[0127] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 92%, the compression modulus was 7.19 MPa, and the impact strength was 0.71 kJ / m 2 The foaming ratio is 23.6 times and the density is 0.062g / cm 3 , the water contact angle is 101.5°.

[0128] Example 15

[0129] A foaming material was prepared by referring to the method of Example 4, except that “30 parts by weight of sweet potato starch, 30 parts by weight of sweet potato starch and 40 parts by weight of cassava starch” were replaced by 100 parts by weight of sweet potato starch.

[0130] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 91%, the compression modulus was 7.43 MPa, and the impact strength was 0.78 kJ / m 2 The foaming ratio is 24.2 times and the density is 0.060g / cm 3 , the water contact angle is 103.9°.

[0131] Example 16

[0132] A foaming material was prepared by referring to the method of Example 4, except that “30 parts by weight of sweet potato starch, 30 parts by weight of yams and 40 parts by weight of tapioca starch” were replaced by 100 parts by weight of tapioca starch.

[0133] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 90%, the compression modulus was 7.58 MPa, and the impact strength was 0.70 kJ / m 2 The foaming ratio is 23.7 times and the density is 0.063g / cm 3 , the water contact angle is 103.2°.

[0134] Example 17

[0135] A foaming material was prepared by referring to the method of Example 4, except that “9 parts by weight of succinic anhydride and 9 parts by weight of stearic acid” were replaced by 18 parts by weight of succinic anhydride.

[0136] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 90%, the compression modulus was 7.22 MPa, and the impact strength was 0.69 kJ / m 2 The foaming ratio is 20.3 times and the density is 0.072g / cm 3 , the water contact angle is 101.1°.

[0137] Example 18

[0138] A foaming material was prepared by referring to the method of Example 4, except that “9 parts by weight of succinic anhydride and 9 parts by weight of stearic acid” were replaced by 18 parts by weight of stearic acid.

[0139] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 92%, the compression modulus was 7.32 MPa, and the impact strength was 0.72 kJ / m 2 The foaming ratio is 24.3 times and the density is 0.060g / cm 3 , the water contact angle is 102.8°.

[0140] Example 19

[0141] A foamed material was prepared by referring to the method of Example 4, except that “8 parts by weight of flax fiber and 8 parts by weight of reed fiber” were replaced by 16 parts by weight of flax fiber.

[0142] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 92%, the compression modulus was 8.01 MPa, and the impact strength was 0.79 kJ / m 2 The foaming ratio is 25.2 times and the density is 0.058g / cm 3 , the water contact angle is 101.5°.

[0143] Example 20

[0144] A foamed material was prepared by referring to the method of Example 4, except that “8 parts by weight of flax fiber and 8 parts by weight of reed fiber” were replaced by 16 parts by weight of reed fiber.

[0145] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 90%, the compression modulus was 7.49 MPa, and the impact strength was 0.70 kJ / m 2 The foaming ratio is 22.8 times and the density is 0.064g / cm 3 , the water contact angle is 104.5°.

[0146] Example 21

[0147] A foaming material was prepared by referring to the method of Example 4, except that “8 parts by weight of polyvinyl alcohol and 9 parts by weight of polybutylene succinate” was replaced by 17 parts by weight of polyvinyl alcohol.

[0148] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 90%, the compression modulus was 7.68 MPa, and the impact strength was 0.75 kJ / m 2 The foaming ratio is 23.5 times and the density is 0.062g / cm 3 , the water contact angle is 99.4°.

[0149] Example 22

[0150] A foaming material was prepared by referring to the method of Example 4, except that “8 parts by weight of polyvinyl alcohol and 9 parts by weight of polybutylene succinate” was replaced by 17 parts by weight of polybutylene succinate.

[0151] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 92%, the compression modulus was 7.36 MPa, and the impact strength was 0.74 kJ / m 2 The foaming ratio is 23.7 times and the density is 0.061g / cm 3 , the water contact angle is 104.9°.

[0152] Example 23

[0153] A foam material was prepared by referring to the method of Example 4, except that “3 parts by weight of titanium dioxide and 4 parts by weight of calcium carbonate” were replaced by 7 parts by weight of titanium dioxide.

[0154] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 91%, the compression modulus was 7.34 MPa, and the impact strength was 0.71 kJ / m 2 The foaming ratio is 24.3 times and the density is 0.060g / cm 3 , the water contact angle is 102.4°.

[0155] Example 24

[0156] A foam material was prepared by referring to the method of Example 4, except that “3 parts by weight of titanium dioxide and 4 parts by weight of calcium carbonate” were replaced by 7 parts by weight of calcium carbonate.

[0157] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 91%, the compression modulus was 7.26 MPa, and the impact strength was 0.76 kJ / m 2The foaming ratio is 22.1 times and the density is 0.066g / cm 3 , the water contact angle is 100.5°.

[0158] Example 25

[0159] A foaming material was prepared by referring to the method of Example 4, except that “2 parts by weight of hexadecanoic acid and 2 parts by weight of acrylate copolymer” was replaced by 4 parts by weight of hexadecanoic acid.

[0160] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 90%, the compression modulus was 7.47 MPa, and the impact strength was 0.78 kJ / m 2 The foaming ratio is 24.6 times and the density is 0.059g / cm 3 , the water contact angle is 101.3°.

[0161] Example 26

[0162] A foaming material was prepared according to the method of Example 4, except that "2 parts by weight of hexadecanoic acid and 2 parts by weight of acrylate copolymer" were replaced by 4 parts by weight of acrylate copolymer (weight-average molecular weight of 70,000), and the mass ratio of butyl acrylate to methyl methacrylate in the acrylate copolymer was 3:2.

[0163] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 91%, the compression modulus was 7.11 MPa, and the impact strength was 0.74 kJ / m 2 The foaming ratio is 22.9 times and the density is 0.06g / cm 3 , the water contact angle is 105.4°.

[0164] Example 27

[0165] A foaming material was prepared according to the method of Example 5, except that “60 parts by weight of 1-hydroxypropyl-3-methylimidazolium acetate ionic liquid, 70 parts by weight of 1-octyl-3-methylnitrate ionic liquid, and 70 parts by weight of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid” were replaced with 200 parts by weight of 1-hydroxypropyl-3-methylimidazolium acetate ionic liquid.

[0166] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 89%, the compression modulus was 7.31 MPa, and the impact strength was 0.81 kJ / m 2 The foaming ratio is 21.5 times and the density is 0.067g / cm 3 , the water contact angle is 102.3°.

[0167] Example 28

[0168] A foaming material was prepared according to the method of Example 5, except that “60 parts by weight of 1-hydroxypropyl-3-methylimidazolium acetate ionic liquid, 70 parts by weight of 1-octyl-3-methylnitrate ionic liquid, and 70 parts by weight of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid” were replaced with 200 parts by weight of 1-octyl-3-methylnitrate ionic liquid.

[0169] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 88%, the compression modulus was 7.22 MPa, and the impact strength was 0.79 kJ / m 2 The foaming ratio is 23.1 times and the density is 0.063g / cm 3 , the water contact angle is 99.9°.

[0170] Example 29

[0171] A foaming material was prepared according to the method of Example 5, except that “60 parts by weight of 1-hydroxypropyl-3-methylimidazolium acetate ionic liquid, 70 parts by weight of 1-octyl-3-methylnitrate ionic liquid, and 70 parts by weight of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid” were replaced with 200 parts by weight of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid.

[0172] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 87%, the compression modulus was 7.31 MPa, and the impact strength was 0.81 kJ / m 2 The foaming ratio is 22.3 times and the density is 0.065g / cm 3 , the water contact angle is 102.6°.

[0173] Example 30

[0174] The foaming material was prepared by referring to the method of Example 5, except that “50 parts by weight of waxy corn amylopectin and 50 parts by weight of potato starch” were replaced with 100 parts by weight of waxy corn amylopectin.

[0175] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 90%, the compression modulus was 7.54 MPa, and the impact strength was 0.79 kJ / m 2 The foaming ratio is 21.7 times and the density is 0.067g / cm 3 , the water contact angle is 100.6°.

[0176] Example 31

[0177] A foaming material was prepared by referring to the method of Example 5, except that “50 parts by weight of waxy corn amylopectin and 50 parts by weight of potato starch” were replaced by 100 parts by weight of potato starch.

[0178] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 86%, the compression modulus was 7.06 MPa, and the impact strength was 0.72 kJ / m 2 The foaming ratio is 23.5 times and the density is 0.062g / cm 3 , the water contact angle is 101.5°.

[0179] Example 32

[0180] A foaming material was prepared by referring to the method of Example 5, except that “10 parts by weight of stearic acid and 10 parts by weight of methyl palmitate” were replaced by 20 parts by weight of stearic acid.

[0181] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 88%, the compression modulus was 7.35 MPa, and the impact strength was 0.84 kJ / m 2 The foaming ratio is 22.9 times and the density is 0.063g / cm 3 , the water contact angle is 101.7°.

[0182] Example 33

[0183] A foaming material was prepared by referring to the method of Example 5, except that “10 parts by weight of stearic acid and 10 parts by weight of methyl palmitate” were replaced by 20 parts by weight of methyl palmitate.

[0184] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 89%, the compression modulus was 7.44 MPa, and the impact strength was 0.87 kJ / m 2 The foaming ratio is 22.5 times and the density is 0.066g / cm 3 , the water contact angle is 100.6°.

[0185] Example 34

[0186] A foamed material was prepared by referring to the method of Example 5, except that “10 parts by weight of jute fiber and 10 parts by weight of cotton fiber” were replaced by 20 parts by weight of jute fiber.

[0187] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 87%, the compression modulus was 6.85 MPa, and the impact strength was 0.83 kJ / m 2 The foaming ratio is 23.2 times and the density is 0.063g / cm 3, the water contact angle is 102.9°.

[0188] Example 35

[0189] A foamed material was prepared by referring to the method of Example 5, except that “10 parts by weight of jute fiber and 10 parts by weight of cotton fiber” were replaced by 20 parts by weight of cotton fiber.

[0190] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 87%, the compression modulus was 7.27 MPa, and the impact strength was 0.75 kJ / m 2 The foaming ratio is 23.5 times and the density is 0.062g / cm 3 , the water contact angle is 99.3°.

[0191] Example 36

[0192] A foam material was prepared by referring to the method of Example 5, except that “10 parts by weight of polybutylene adipate / terephthalate and 10 parts by weight of polybutylene succinate” were replaced with 20 parts by weight of polybutylene adipate / terephthalate.

[0193] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 90%, the compression modulus was 7.55 MPa, and the impact strength was 0.89 kJ / m 2 The foaming ratio is 21.1 times and the density is 0.068g / cm 3 , the water contact angle is 100.7°.

[0194] Example 37

[0195] A foam material was prepared by referring to the method of Example 5, except that “10 parts by weight of polybutylene adipate / terephthalate and 10 parts by weight of polybutylene succinate” were replaced with 20 parts by weight of polybutylene succinate.

[0196] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 88%, the compression modulus was 7.99 MPa, and the impact strength was 0.79 kJ / m 2 The foaming ratio is 23.0 times and the density is 0.063g / cm 3 , the water contact angle is 101.4°.

[0197] Example 38

[0198] A foamed material was prepared by referring to the method of Example 5, except that “5 parts by weight of calcium carbonate and 5 parts by weight of zinc oxide” were replaced by 10 parts by weight of calcium carbonate.

[0199] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 86%, the compression modulus was 7.33 MPa, and the impact strength was 0.78 kJ / m 2 The foaming ratio is 21.4 times and the density is 0.067g / cm 3 , the water contact angle is 98.8°.

[0200] Example 39

[0201] A foamed material was prepared by referring to the method of Example 5, except that “5 parts by weight of calcium carbonate and 5 parts by weight of zinc oxide” were replaced by 10 parts by weight of zinc oxide.

[0202] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 87%, the compression modulus was 7.21 MPa, and the impact strength was 0.77 kJ / m 2 The foaming ratio is 22.1 times and the density is 0.065g / cm 3 , the water contact angle is 101.0°.

[0203] Example 40

[0204] A foaming material was prepared by referring to the method of Example 5, except that “2.5 parts by weight of dispersed rosin size and 2.5 parts by weight of paraffin wax” were replaced with 5 parts by weight of dispersed rosin size.

[0205] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 87%, the compression modulus was 7.31 MPa, and the impact strength was 0.84 kJ / m 2 The foaming ratio is 23.4 times and the density is 0.061g / cm 3 , the water contact angle is 102.2°.

[0206] Example 41

[0207] A foaming material was prepared by referring to the method of Example 5, except that “2.5 parts by weight of dispersed rosin size and 2.5 parts by weight of paraffin wax” were replaced with 5 parts by weight of paraffin wax.

[0208] The prepared foam material was tested, and the results showed that the rebound rate of the foamed particles was 89%, the compression modulus was 7.45 MPa, and the impact strength was 0.80 kJ / m 2 The foaming ratio is 22.3 times and the density is 0.065g / cm 3 , the water contact angle is 100.8°.

[0209] Comparative Example 1

[0210] First, 400 parts by weight of tap water, 100 parts by weight of 200-mesh corn amylose, and 10 parts by weight of maleic anhydride were placed in a reactor and fully mixed for 2 hours. The mixing temperature was set to 60°C and the speed was set to 200 rpm. Then, 5 parts by weight of 200-mesh polybutylene adipate / terephthalate (weight-average molecular weight of 100,000, with a molar ratio of aliphatic polyester (BA) repeating units to aromatic polyester (BT) repeating units of 60:40) were added and mixed at the same speed for 40 minutes. The mixture was then separated in a high-speed centrifuge at a speed of 5000 rpm, washed repeatedly with anhydrous ethanol, and centrifuged three times. The obtained precipitate was dried at 60°C.

[0211] The dried material was added to a high-speed mixer, and 5 parts by weight of tap water as a foaming agent and 2 parts by weight of silicon dioxide with a particle size of 50 nm were added at the same time. The mixture was stirred at room temperature for 10 min at a stirring speed of 500 rpm. After thorough mixing, the mixture was melt-blended in a single-screw extruder and extruded for foaming. The temperature of the blending zone was set to 160°C, the die extrusion temperature was set to 140°C, the screw speed was set to 150 rpm, and the die extrusion diameter was 1 mm.

[0212] The foamed material obtained by extrusion was tested, and the results showed that the rebound rate of the foamed particles was 54%, the compression modulus was 2.15 MPa, and the impact strength was 0.29 kJ / m 2 , the foaming ratio is 7.6 times, and the density is 0.17g / cm 3 , the water contact angle is 58.6.

[0213] Comparative Example 2

[0214] First, 400 parts by weight of tap water, 100 parts by weight of corn amylose with a mesh size of 200 mesh, and 5 parts by weight of straw fiber with a length of 2 mm and a diameter of 30 μm were placed in a reactor and fully mixed for 2.5 hours. The mixing temperature was set to 65°C and the speed was set to 200 rpm; then 7 parts by weight of polybutylene adipate / terephthalate with a mesh size of 250 mesh (weight-average molecular weight of 100,000, wherein the molar ratio of aliphatic polyester (BA) repeating units to aromatic polyester (BT) repeating units is 60:40) were added and mixed at the same speed for 50 minutes; then the mixture was separated in a high-speed centrifuge with a speed set to 6000 rpm, and then repeatedly washed and centrifuged with anhydrous ethanol three times, and the obtained precipitate was dried at 65°C.

[0215] The dried material was added to a high-speed mixer, and 5 parts by weight of tap water as a foaming agent, 2 parts by weight of talc with a particle size of 50 nm, and 1 part by weight of paraffin were added. The mixture was stirred at room temperature for 10 min at a stirring speed of 500 rpm. After thorough mixing, the mixture was melt-blended in a single-screw extruder and extruded for foaming. The temperature in the blending zone was set to 160°C, the die extrusion temperature was set to 140°C, the screw speed was set to 150 rpm, and the die extrusion diameter was 1 mm.

[0216] The foamed material obtained by extrusion was tested, and the results showed that the rebound rate of the foamed particles was 50%, the compression modulus was 1.94 MPa, and the impact strength was 0.31 kJ / m 2 , the foaming ratio is 6.6 times, and the density is 0.20g / cm 3 , the water contact angle is 63.8°.

[0217] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a degradable starch foaming buffer material, comprising the following steps: a) mixing starch, ionic liquid, water and starch modifier for reaction, then mixing with plant fiber and biodegradable resin, removing the liquid phase to obtain a solid material; The ionic liquid is 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid and 1-butyl-3-methylimidazolium dicyanamide ionic liquid, and the mass ratio of the 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid and the 1-butyl-3-methylimidazolium dicyanamide ionic liquid is 1:(0.5-2); or the ionic liquid is 1-butyl-3-methylimidazolium dicyanamide ionic liquid and 1,3-dimethylimidazolium methyl phosphite ionic liquid, and the mass ratio of the 1-butyl-3-methylimidazolium dicyanamide ionic liquid and the 1,3-dimethylimidazolium methyl phosphite ionic liquid is 1:(0.5-2). The mass ratio of 3-dimethylimidazolium methyl phosphite ionic liquid is 1:(0.5-2); or, the ionic liquid is 1-hydroxypropyl-3-methylimidazolium acetate ionic liquid, 1-octyl-3-methylnitrate ionic liquid and 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid, and the mass ratio of the 1-hydroxypropyl-3-methylimidazolium acetate ionic liquid, 1-octyl-3-methylnitrate ionic liquid and 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid is 6:(5-10):(5-10); Based on 100 parts by weight of the starch, the total amount of the ionic liquid and water is 400 to 500 parts by weight, and the mass ratio of the ionic liquid to water is (1 to 2):3; b) melt-blending the solid material, the foaming agent and the nucleating agent and then foaming and molding the mixture to obtain a degradable starch foaming cushioning material.

2. The preparation method according to claim 1, characterized in that The starch modifier is one or more of maleic anhydride, succinic anhydride, vinyl acetate, methyl palmitate, lauric acid and stearic acid.

3. The preparation method according to claim 1, characterized in that The starch is one or more of corn amylose, waxy corn amylopectin, wheat starch, barley starch, rice starch, potato starch, sweet potato starch, yams starch and tapioca 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; The biodegradable resin is one or more of polybutylene adipate / terephthalate, polyvinyl alcohol, polybutylene succinate and polypropylene carbonate.

4. The preparation method according to claim 1, characterized in that The foaming agent is one or more of tap water, distilled water, deionized water, high-purity water and reverse osmosis water; The nucleating agent is one or more of silicon dioxide, talc, titanium dioxide, calcium carbonate, zinc oxide and montmorillonite.

5. The preparation method according to claim 1, characterized in that Based on 100 parts by weight of the starch, the amount of the starch modifier is 10 to 20 parts by weight; the amount of the plant fiber is 5 to 20 parts by weight; the amount of the biodegradable resin is 5 to 20 parts by weight; the amount of the foaming agent is 5 to 15 parts by weight; and the amount of the nucleating agent is 2 to 10 parts by weight.

6. The preparation method according to claim 1, characterized in that The temperature of the mixed reaction is 60-80° C.; the time of the mixed reaction is 2-4 hours.

7. The preparation method according to claim 1, characterized in that A water-proofing agent is also added during the melt blending process.

8. The preparation method according to claim 7, characterized in that The waterproofing agent is one or more of acrylate copolymer, hexadecanoic acid, organosilicon waterproofing agent, dispersed rosin glue and paraffin.

9. A degradable starch foaming buffer material prepared by the preparation method according to any one of claims 1 to 8.