Supercritical foaming sole and preparation method thereof

Abstract

The invention discloses a supercritical foaming shoe sole and a preparation method thereof, and relates to the technical field of foaming materials, the foaming shoe sole is prepared from the following components by weight: 80-100 parts of TPU, 20-30 parts of calcium carbonate, 2-10 parts of N-hydroxymethyl acrylamide, 4-12 parts of modified graphene oxide, 1-5 parts of zinc stearate, 1-5 parts of dimethylaminobenzene, 1-5 parts of vinyl cyclooctene, 0.1-1 part of an antioxidant 1010, and 0.1-1 part of benzophenone; the obtained product has excellent foaming uniformity and weight reduction effect, and keeps good mechanical property balance; the shoe material not only shows excellent wear resistance and durability, but also has remarkable antibacterial and deodorant effects, and effectively solves various problems of traditional foaming soles in practical application.

Description

Technical Field

[0001] The present invention relates to the technical field of foaming materials, and particularly relates to a supercritical foamed sole and a preparation method thereof. Background Art

[0002] After years of development, the sole materials of sports shoes have formed a variety of common material systems such as rubber, EVA, PU, and TPU. Among them, rubber has excellent abrasion resistance and anti-slip performance, but has a relatively large density; EVA foaming material is light in weight and good in shock absorption, but has poor abrasion resistance and durability; PU material has good mechanical properties and hydrolysis resistance, but the processing technology is complex and the production efficiency is low. Thermoplastic polyurethane (TPU), as an emerging sole material, combines the high elasticity of rubber and the processing performance of plastic, has excellent mechanical properties, abrasion resistance, oil resistance, low temperature resistance, etc., and can be recycled and reused, meeting the environmental protection requirements. Therefore, it has been widely used in the field of sports shoe soles.

[0003] The sole material prepared by TPU has the following significant advantages: a wide hardness range (60A - 75D), which can meet the requirements of different application scenarios; high tensile strength (≥25 MPa), large elongation at break (≥450%), and good fatigue resistance; moderate density (1.12 - 1.25 g / cm 3 ), and excellent abrasion resistance and oil resistance. However, the density of TPU soles is still relatively high, and reducing the density through the foaming process has become an important way to enhance its competitiveness. However, although the traditional physical foaming process can reduce the sole density, problems such as uneven foaming and obvious decline in mechanical properties still exist.

[0004] CN118636513A A molding method for a supercritical insole of TPU popcorn shoes, comprising the following steps: preparing corresponding weights of TPU popcorn beads; placing the TPU popcorn beads in a shoe material mold, and then closing the mold; heating the shoe material mold to raise the temperature of the shoe material mold to 130 - 145 degrees Celsius for vulcanization treatment, so that the surface of the TPU popcorn beads in the shoe material mold melts, and the melting degree does not extend into the hollow cavity of the TPU popcorn. Adjacent TPU popcorn beads penetrate and combine with each other using the molten state on the surface; cooling the shoe material mold. After cooling, the TPU popcorn beads in the shoe material are formed into an insole at one time, opening the mold and taking out the insole to complete the preparation.

[0005] As a new type of environmentally friendly foaming process, the supercritical fluid foaming technology has the advantages of less foaming agent residue, uniform foaming, and process controllability, and shows good application prospects in the field of sole material foaming. However, the TPU soles prepared solely by the supercritical foaming process still face the following problems in actual applications:

[0006] During the foaming process, it is difficult to control the bubble size and the bubble distribution is uneven, resulting in unstable sole performance; after foaming, the mechanical properties of the material, especially hardness and tear strength, are significantly reduced, affecting the service life of the product; during long-term wearing, due to foot sweating, bacterial growth and other reasons, it is easy to produce peculiar smell, affecting the use experience.

[0007] To solve the above problems, researchers have tried to add inorganic fillers and modifiers to TPU, but often can only improve the performance in one aspect. For example, adding calcium carbonate can improve the foaming uniformity, but the improvement of mechanical properties is limited; adding antibacterial agents can inhibit bacterial growth, but it is easy to affect the processing performance of the material. Therefore, it is of great significance to develop a new modification method that can simultaneously improve the mechanical properties and antibacterial and odor-proof properties of TPU foamed soles. Summary of the Invention

[0008] In order to solve the deficiencies of the existing technology, the purpose of the present invention is to provide a supercritical foamed sole and its preparation method. The obtained product has excellent foaming uniformity and weight reduction effect, while maintaining a good balance of mechanical properties; the product not only exhibits excellent wear resistance and durability, but also has a significant antibacterial and odor-proof effect, effectively solving various problems existing in the actual application of traditional foamed soles.

[0009] To achieve the above purpose, the present invention adopts the following technical solutions:

[0010] A supercritical foamed sole is made of the following components in parts by weight: 80-100 parts of TPU, 20-30 parts of calcium carbonate, 2-10 parts of N-hydroxymethylacrylamide, 4-12 parts of modified graphene oxide, 1-5 parts of zinc stearate, 1-5 parts of dimethylaminobenzene, 1-5 parts of vinylcyclooctene, 0.1-1 part of antioxidant 1010, and 0.1-1 part of benzophenone.

[0011] Preferably, the preparation method of the modified graphene oxide includes the following steps:

[0012] (1) Disperse graphene oxide in DMF, perform ultrasonic treatment, add 4,4-diaminodiphenyl sulfone, then add EDC and NHS, stir and react, filter, wash and dry the product to obtain sulfonated graphene;

[0013] Carboxyl activation coupling reaction: EDC first reacts with the carboxyl group (-COOH) on the surface of graphene oxide to form an O-acylurea intermediate, and NHS undergoes transesterification with this intermediate to obtain an active ester intermediate; subsequently, the amino group (-NH2) of 4,4-diaminodiphenyl sulfone performs a nucleophilic attack on the active ester, and an arylamine group containing a sulfonyl group (-SO 2- ) is introduced onto the graphene surface through an amidation reaction, while releasing NHS.

[0014] Preferably, in step (1), the dosage ratio of graphene oxide, DMF, 4,4-diaminodiphenyl sulfone, EDC, and NHS is 10 g: 80 - 120 mL: 8 - 12 g: 4 - 6 g: 2 - 3 g.

[0015] Preferably, in step (1), the stirring reaction conditions are stirring reaction at 100 - 130 °C for 8 - 16 h.

[0016] Preferably, in step (1), ultrasonic treatment is carried out for 20 - 40 min; the product is washed 3 - 5 times with DMF and deionized water in sequence.

[0017] (2) Disperse sulfonated graphene in DMF, carry out ultrasonic treatment, slowly add dicyandiamide solution under ice bath conditions, raise the temperature for reaction, filter, wash, and dry the product to obtain the modified graphene oxide.

[0018] Addition reaction of arylamine group and dicyandiamide: The arylamine group (-NH2) on the surface of sulfonated graphene acts as a nucleophile to attack the carbon-nitrogen triple bond (-C≡N) in the dicyandiamide molecule to carry out an addition reaction, forming a carbon-nitrogen double bond structure (-C=N-). Since there are multiple reaction sites in the dicyandiamide molecule, through low-temperature dropping and mild reaction conditions, side reactions such as self-addition of dicyandiamide molecules and cross-linking with multiple reaction sites can be inhibited.

[0019] Preferably, in step (2), the dosage ratio of sulfonated graphene, DMF, and dicyandiamide solution is 10 g: 50 - 100 mL: 50 mL; the concentration of the dicyandiamide solution is 5 - 8 g / 50 mL.

[0020] Preferably, in step (2), the ice bath conditions are 0 - 5 °C; the temperature-raising reaction conditions are reaction at 50 - 80 °C for 4 - 8 h.

[0021] Preferably, in step (2), ultrasonic treatment is carried out for 20 - 40 min; the product is washed 3 - 5 times with DMF and deionized water.

[0022] The present invention also claims to protect a preparation method of the supercritical foaming sole, including the following steps: mixing raw materials to make a sheet, placing the sheet in a mold cavity for supercritical foaming to obtain a foamed body, cutting the foamed body into required shapes and sizes, and polishing to obtain the supercritical foaming sole.

[0023] Preferably, the supercritical foaming is: introducing nitrogen or carbon dioxide into the mold cavity, raising the temperature to 100 - 160 °C, pressurizing to 10 - 70 MPa to make it reach the supercritical state, maintaining at a constant temperature and constant pressure for 1 - 5 h after reaching the supercritical state, and then quickly releasing the pressure to atmospheric pressure to obtain a foamed body.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention provides a supercritical foamed sole. TPU is used as the matrix material to provide good mechanical properties and wear resistance; calcium carbonate can not only increase the rigidity and hardness of the material, but also act as a heterogeneous nucleating agent to promote the uniform nucleation of bubbles during the foaming process; N-hydroxymethyl acrylamide is used as a crosslinking agent to increase the crosslinking density and mechanical strength of the material; zinc stearate is used as a lubricant to improve the processing performance; dimethyl aminobenzene is used as a plasticizer to improve the processing fluidity and flexibility of the material; vinyl cyclooctene participates in the crosslinking reaction to adjust the elastic modulus of the material; antioxidant 1010 and benzophenone are used as thermal oxidation protectant and light stabilizer respectively to improve the weather resistance of the material. Among them, modified graphene oxide enhances the mechanical properties of the material through the rigid groups introduced on the surface, and at the same time has antibacterial and odor-proof effects.

[0026] 2. The present invention provides a modified graphene oxide. In the first step, an aromatic structure containing a sulfone group is introduced onto the surface of graphene oxide through an amidation reaction. The presence of the rigid benzene ring and sulfone group not only enhances the interfacial compatibility with the TPU matrix, but also improves the properties such as the hardness and tear strength of the sole material, while maintaining a high elongation at break, making the material have excellent elasticity and toughness; in the second step, a guanidine group structure is constructed on the surface, which can effectively inhibit the microbial activity, inhibit the generation of malodorous substances, and improve the odor-proof effect of the sole material. In addition, the excellent mechanical properties and two-dimensional sheet structure of graphene oxide itself can form an effective stress transfer network in the TPU matrix, forming a synergistic effect with the strengthening effect of the benzene ring and sulfone group; at the same time, the inherent antibacterial activity of graphene oxide and the guanidine group introduced on the surface produce a synergistic effect, further enhancing the comprehensive antibacterial performance of the material, effectively solving the problems of bacterial growth and odor in the use process of sports shoes and other products. Detailed implementation manners

[0027] In order to make the purpose, technical solutions and advantages of the present invention clearer, the following further elaborates on the present invention in combination with embodiments. Of course, the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased through the market or synthesized from raw materials purchased through the market.

[0029] The TPU resin is purchased from Bayer of Germany, grade: 8792A-S043;

[0030] The calcium carbonate is heavy calcium carbonate with a particle size of 1250 mesh and a whiteness of ≥94%, purchased from Jiangsu Yifeng Powder Raw Material Co., Ltd., grade: Yf-225;

[0031] Graphene oxide was purchased from Shanghai Liwusheng Nano Technology Co., Ltd., production number: LN-F-S.

[0032] A preparation method of a supercritical foamed sole, comprising the following steps:

[0033] (1) Disperse 10 g of graphene oxide in 80 - 120 mL of DMF, ultrasonically treat for 20 - 40 min, add 8 - 12 g of 4,4-diaminodiphenyl sulfone, then add 4 - 6 g of EDC and 2 - 3 g of NHS, stir and react at 100 - 130 °C for 8 - 16 h, filter the product, wash it 3 - 5 times with DMF and deionized water respectively, and dry to obtain sulfonated graphene;

[0034] (2) Disperse 10 g of sulfonated graphene in 50 - 100 mL of DMF, ultrasonically treat for 20 - 40 min, slowly add 50 mL of dicyandiamide solution (concentration 5 - 8 g / 50 mL) under the condition of an ice bath at 0 - 5 °C, raise the temperature to 50 - 80 °C and react for 4 - 8 h, filter the product, wash it 3 - 5 times with DMF and deionized water, and dry to obtain the modified graphene oxide;

[0035] (3) Mix 80 - 100 parts of TPU, 20 - 30 parts of calcium carbonate, 2 - 10 parts of N-methylolacrylamide, 4 - 12 parts of modified graphene oxide, 1 - 5 parts of zinc stearate, 1 - 5 parts of dimethylaminobenzene, 1 - 5 parts of vinylcyclooctene, 0.1 - 1 part of antioxidant 1010, and 0.1 - 1 part of benzophenone to make a sheet, place the sheet in a mold cavity, introduce nitrogen or carbon dioxide into the mold cavity, raise the temperature to 100 - 160 °C, pressurize to 10 - 70 MPa to make it reach the supercritical state, keep it at a constant temperature and pressure for 1 - 5 h after reaching the supercritical state, then quickly release the pressure to atmospheric pressure to obtain a foam, cut the foam into the required shape and size, and polish to obtain the supercritical foamed sole.

[0036] The following is a further description of the present invention through specific examples.

[0037] Example 1

[0038] A preparation method of a supercritical foamed sole, comprising the following steps:

[0039] (1) Disperse 10 g of graphene oxide in 100 mL of DMF, ultrasonically treat for 30 min, add 12 g of 4,4-diaminodiphenyl sulfone, then add 6 g of EDC and 3 g of NHS, stir and react at 130 °C for 8 h, filter the product, wash it 4 times with DMF and deionized water respectively, and dry to obtain sulfonated graphene;

[0040] (2) Disperse 10 g of sulfonated graphene in 100 mL of DMF, ultrasonically treat for 30 min, slowly add 50 mL of dicyandiamide solution (concentration 8 g / 50 mL) under the condition of an ice bath at 3 °C, raise the temperature to 80 °C and react for 4 h, filter the product, wash it 4 times successively with DMF and deionized water, and dry it to obtain the modified graphene oxide;

[0041] (3) Knead 1000 g of TPU, 300 g of calcium carbonate, 100 g of N-methylolacrylamide, 120 g of modified graphene oxide, 50 g of zinc stearate, 50 g of dimethylaminobenzene, 50 g of vinylcyclooctene, 10 g of antioxidant 1010, and 10 g of benzophenone into a sheet, place the sheet in a mold cavity, introduce nitrogen or carbon dioxide into the mold cavity, raise the temperature to 130 °C and pressurize to 40 MPa to make it reach the supercritical state. After reaching the supercritical state, keep it at a constant temperature and pressure for 3 h, and then quickly release the pressure to atmospheric pressure to obtain a foam. Cut the foam into the required shape and size and polish it to obtain the supercritical foamed sole.

[0042] Example 2

[0043] A method for preparing a supercritical foamed sole, comprising the following steps:

[0044] (1) Disperse 10 g of graphene oxide in 100 mL of DMF, ultrasonically treat for 30 min, add 10 g of 4,4-diaminodiphenyl sulfone, then add 5 g of EDC and 2.5 g of NHS, stir and react at 120 °C for 10 h, filter the product, wash it 4 times successively with DMF and deionized water respectively, and dry it to obtain sulfonated graphene;

[0045] (2) Disperse 10 g of sulfonated graphene in 100 mL of DMF, ultrasonically treat for 30 min, slowly add 50 mL of dicyandiamide solution (concentration 7 g / 50 mL) under the condition of an ice bath at 3 °C, raise the temperature to 70 °C and react for 5 h, filter the product, wash it 4 times successively with DMF and deionized water, and dry it to obtain the modified graphene oxide;

[0046] (3) Knead 920 g of TPU, 260 g of calcium carbonate, 70 g of N-methylolacrylamide, 100 g of modified graphene oxide, 40 g of zinc stearate, 40 g of dimethylaminobenzene, 40 g of vinylcyclooctene, 8 g of antioxidant 1010, and 8 g of benzophenone into a sheet, place the sheet in a mold cavity, introduce nitrogen or carbon dioxide into the mold cavity, raise the temperature to 130 °C and pressurize to 40 MPa to make it reach the supercritical state. After reaching the supercritical state, keep it at a constant temperature and pressure for 3 h, and then quickly release the pressure to atmospheric pressure to obtain a foam. Cut the foam into the required shape and size and polish it to obtain the supercritical foamed sole.

[0047] Example 3

[0048] A method for preparing a supercritical foamed sole, comprising the following steps:

[0049] (1) Disperse 10 g of graphene oxide in 100 mL of DMF, ultrasonically treat for 30 min, add 10 g of 4,4-diaminodiphenyl sulfone, then add 5 g of EDC and 2.5 g of NHS, stir and react at 110 °C for 12 h, filter the product, wash it 4 times with DMF and deionized water respectively, and dry it to obtain sulfonated graphene;

[0050] (2) Disperse 10 g of sulfonated graphene in 100 mL of DMF, ultrasonically treat for 30 min, slowly add 50 mL of dicyandiamide solution (concentration 6 g / 50 mL) under the condition of an ice bath at 3 °C, raise the temperature to 60 °C and react for 6 h, filter the product, wash it 4 times with DMF and deionized water, and dry it to obtain the modified graphene oxide;

[0051] (3) Knead 860 g of TPU, 240 g of calcium carbonate, 40 g of N-hydroxymethylacrylamide, 60 g of modified graphene oxide, 20 g of zinc stearate, 20 g of dimethylaminobenzene, 20 g of vinylcyclooctene, 4 g of antioxidant 1010, and 4 g of benzophenone into a sheet, place the sheet in a mold cavity, introduce nitrogen or carbon dioxide into the mold cavity, raise the temperature to 130 °C and pressurize to 40 MPa to make it reach the supercritical state, keep it at a constant temperature and pressure for 3 h after reaching the supercritical state, then quickly release the pressure to atmospheric pressure to obtain a foam body, cut the foam body into the required shape and size, and polish it to obtain the supercritical foamed sole.

[0052] Example 4

[0053] A method for preparing a supercritical foamed sole, comprising the following steps:

[0054] (1) Disperse 10 g of graphene oxide in 100 mL of DMF, ultrasonically treat for 30 min, add 8 g of 4,4-diaminodiphenyl sulfone, then add 4 g of EDC and 2 g of NHS, stir and react at 100 °C for 16 h, filter the product, wash it 4 times with DMF and deionized water respectively, and dry it to obtain sulfonated graphene;

[0055] (2) Disperse 10 g of sulfonated graphene in 100 mL of DMF, ultrasonically treat for 30 min, slowly add 50 mL of dicyandiamide solution (concentration 5 g / 50 mL) under the condition of an ice bath at 3 °C, raise the temperature to 50 °C and react for 8 h, filter the product, wash it 4 times with DMF and deionized water, and dry it to obtain the modified graphene oxide;

[0056] (3) Mix 800 g of TPU, 200 g of calcium carbonate, 20 g of N - hydroxymethylacrylamide, 40 g of modified graphene oxide, 10 g of zinc stearate, 10 g of dimethylaminobenzene, 10 g of vinylcyclooctene, 1 g of antioxidant 1010, and 1 g of benzophenone to form a sheet. Place the sheet in the mold cavity, introduce nitrogen or carbon dioxide into the mold cavity, heat to 130 °C, and pressurize to 40 MPa to make it reach the supercritical state. After reaching the supercritical state, keep it at a constant temperature and pressure for 3 h, and then quickly release the pressure to atmospheric pressure to obtain a foam. Cut the foam into the required shape and size, and polish to obtain the supercritical foamed sole.

[0057] Comparative Example 1

[0058] A preparation method of a supercritical foamed sole, comprising the following steps:

[0059] (1) Disperse 10 g of graphene oxide in 100 mL of DMF, ultrasonically treat for 30 min, add 12 g of 4,4 - diaminodiphenyl sulfone, then add 6 g of EDC and 3 g of NHS, stir and react at 130 °C for 8 h. Filter the product, wash it 4 times with DMF and deionized water respectively, and dry to obtain sulfonated graphene.

[0060] (2) Mix 1000 g of TPU, 300 g of calcium carbonate, 100 g of N - hydroxymethylacrylamide, 120 g of sulfonated graphene, 50 g of zinc stearate, 50 g of dimethylaminobenzene, 50 g of vinylcyclooctene, 10 g of antioxidant 1010, and 10 g of benzophenone to form a sheet. Place the sheet in the mold cavity, introduce nitrogen or carbon dioxide into the mold cavity, heat to 130 °C, and pressurize to 40 MPa to make it reach the supercritical state. After reaching the supercritical state, keep it at a constant temperature and pressure for 3 h, and then quickly release the pressure to atmospheric pressure to obtain a foam. Cut the foam into the required shape and size, and polish to obtain the supercritical foamed sole.

[0061] Comparative Example 2

[0062] A preparation method of a supercritical foamed sole, comprising the following steps:

[0063] Mix 1000 g of TPU, 300 g of calcium carbonate, 100 g of N - hydroxymethylacrylamide, 120 g of graphene oxide, 50 g of zinc stearate, 50 g of dimethylaminobenzene, 50 g of vinylcyclooctene, 10 g of antioxidant 1010, and 10 g of benzophenone to form a sheet. Place the sheet in the mold cavity, introduce nitrogen or carbon dioxide into the mold cavity, heat to 130 °C, and pressurize to 40 MPa to make it reach the supercritical state. After reaching the supercritical state, keep it at a constant temperature and pressure for 3 h, and then quickly release the pressure to atmospheric pressure to obtain a foam. Cut the foam into the required shape and size, and polish to obtain the supercritical foamed sole.

[0064] The performance of the foamed sole materials prepared in Examples 1 to 4 and Comparative Examples 1 to 2 was tested. The elongation at break and tensile strength were tested with reference to GB / T 6344-2008 "Determination of Tensile Strength and Elongation at Break of Flexible Cellular Plastics"; the hardness was tested with reference to GB / T 3903.4-2017 "Test Methods for Whole Shoes - Hardness"; the compression set was tested with reference to HG / T 2876-2009 "Test Method for Compression Set of Rubber and Plastic Shoes Microporous Materials"; the dimensional stability was tested with reference to HG / T 2874-1997 "Determination of Thermal Shrinkage of Microporous Materials for Shoes"; the antibacterial property was tested with reference to HG / T 3663-2014 "Test Method for Antibacterial Property of Rubber Shoes", and the width of the antibacterial zone was recorded. The test bacteria were Escherichia coli and Staphylococcus aureus. The specific data are shown in Table 1.

[0065] Table 1 Test Results of Foamed Shoe Material Performance

[0066]

[0067]

[0068] The above is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A supercritical foaming sole, characterized in that: The invention is prepared from the following components in parts by weight: 80-100 parts of TPU, 20-30 parts of calcium carbonate, 2-10 parts of N-hydroxymethyl acrylamide, 4-12 parts of modified graphene oxide, 1-5 parts of zinc stearate, 1-5 parts of dimethylaminobenzene, 1-5 parts of vinyl cyclooctene, 0.1-1 parts of antioxidant 1010 and 0.1-1 parts of benzophenone.

2. The supercritical foaming sole according to claim 1, characterized in that: The preparation method of the modified graphene oxide comprises the following steps: (1) dispersing graphene oxide in DMF, ultrasonically treating, adding 4,4-diaminodiphenyl sulfone, then adding EDC and NHS, stirring for reaction, filtering, washing and drying the product to obtain sulfonated graphene; (2) dispersing the sulfonated graphene in DMF, ultrasonically treating it, slowly adding a dicyandiamide solution in an ice bath, heating it for reaction, filtering, washing, and drying the product to obtain the modified graphene oxide.

3. The supercritical foaming sole according to claim 2, characterized in that: In step (1), the usage ratio of graphene oxide, DMF, 4,4-diaminodiphenyl sulfone, EDC and NHS is 10 g: 80-120 mL: 8-12 g: 4-6 g: 2-3 g.

4. The supercritical foaming sole according to claim 2, characterized in that: In step (1), the stirring reaction conditions are 100-130° C. for 8-16 hours.

5. The supercritical foaming sole according to claim 2, characterized in that: In step (1), the ultrasonic treatment is performed for 20 to 40 minutes; and the product is washed with DMF and deionized water for 3 to 5 times respectively.

6. The supercritical foaming sole according to claim 2, characterized in that: In step (2), the usage ratio of sulfonated graphene, DMF and dicyandiamide solution is 10 g:50-100 mL:50 mL; the concentration of dicyandiamide solution is 5-8 g / 50 mL.

7. The supercritical foaming sole according to claim 2, characterized in that: In step (2), the ice bath condition is 0-5°C; the temperature reaction condition is 50-80°C for 4-8h.

8. The supercritical foaming sole according to claim 2, characterized in that: In step (2), ultrasonic treatment is performed for 20 to 40 minutes; and the product is washed with DMF and deionized water for 3 to 5 times in sequence.

9. A method for preparing a supercritical foamed shoe sole according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: mixing raw materials into sheets, placing the sheets in a mold cavity for supercritical foaming to obtain a foam body, cutting the foam body into required shapes and sizes, and polishing to obtain the supercritical foamed sole.

10. The preparation method according to claim 9, characterized in that: The supercritical foaming is as follows: nitrogen or carbon dioxide is introduced into the mold cavity, the temperature is raised to 100-160° C., and the pressure is increased to 10-70 MPa to make it reach a supercritical state, after reaching the supercritical state, the temperature and pressure are maintained at a constant level for 1-5 hours, and then the pressure is rapidly released to normal pressure to obtain a foamed body.

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