Lightweight foaming sole material and preparation method thereof

Abstract

The invention relates to a lightweight foaming sole material, which comprises the following raw materials by mass: 20-30% of a PA / EBA modified blend; 10% to 20% of a TPEE / EBA modified blend; 10%-30% of an ethylene-butyl acrylate copolymer (EBA); 8%-15% of an ethylene-octylene copolymer POE; 8%-15% of brominated butyl rubber BIIR; 2%-3% of talcum powder; 5%-10% of a coupling agent; 0.5%-1% of a lubricant; 1%-2% of a foaming aid; 0.3%-1% of a cross-linking agent; and 3%-7% of a foaming agent. The foaming sole material provided by the invention has the advantages of high elasticity, tear resistance and wrinkle resistance; the preparation method is simple and low in production cost, and has a wide application prospect in the field of foamed sole materials.

Description

Technical Field

[0001] The patent of this invention relates to the technical field of shoe materials, in particular to a lightweight foamed sole material and a preparation method thereof. Background Art

[0002] In the footwear industry, lightweight, low-density shoe materials are primarily achieved through high foaming rates. Traditional secondary compression chemical foaming methods, with a maximum foaming rate of approximately 190%, are prone to tearing, poor rebound, and wrinkling and deformation, as the primary material is typically EVA. This high foaming rate results in shoe soles that are difficult to meet consumer demands.

[0003] PA (nylon) and TPEE (thermoplastic polyester elastomer) have the advantages of high elasticity and high strength, so they have become hot spots in the research and development of high-ratio lightweight foaming materials. Due to the high melting point and strong inertness of PA and TPEE materials, it is difficult to achieve cross-linking foaming. Not only can they not be chemically foamed alone, but they are also not compatible with other materials in the foaming system for chemical foaming. They cannot be directly applied to the secondary molding high-ratio foaming process. The industry mostly uses supercritical physical foaming technology to prepare foaming materials containing PA and TPEE, but this method is complex, has a very high scrap rate, and is extremely expensive to produce, which greatly limits the application of this type of foaming material in lightweight, low-density footwear. Summary of the Invention

[0004] The purpose of the present invention is to solve the existing technical problems and propose a lightweight foam sole material that has the advantages of high elasticity, tear resistance and wrinkle resistance; another purpose of the present invention is to provide a method for preparing the foam material, which is simple and has low production cost.

[0005] In order to achieve the above-mentioned object, the present invention adopts the following technical solution: a lightweight foam sole material, comprising the following raw materials in the following mass percentages:

[0006] PA / EBA modified blend: 20% to 30%;

[0007] TPEE / EBA modified blend: 10% to 20%;

[0008] Ethylene-butyl acrylate copolymer EBA: 10% to 30%;

[0009] Ethylene-octene copolymer POE: 8% to 15%;

[0010] Bromobutyl rubber BIIR: 8% to 15%;

[0011] Talc: 2% to 3%;

[0012] Coupling agent: 5% to 10%;

[0013] Lubricant: 0.5% to 1%;

[0014] Foaming aid: 1% to 2%;

[0015] Cross-linking agent: 0.3% to 1%;

[0016] Foaming agent: 3%~7%.

[0017] Preferably, the PA / EBA modified blend comprises the following raw materials in percentage by mass: PA: 45%;

[0018] Ethylene-butyl acrylate copolymer EBA: 45%;

[0019] Ethylene-acrylic acid maleic anhydride graft copolymer EAA: 9.4%;

[0020] Lubricant: 0.6%.

[0021] A lightweight foam sole material comprises the following raw materials in percentage by mass: PA / EBA modified blend: 30%;

[0022] TPEE / EBA modified blend: 20%;

[0023] Ethylene-butyl acrylate copolymer EBA: 10%;

[0024] Ethylene-octene copolymer POE: 10%;

[0025] Bromobutyl rubber BIIR: 10%;

[0026] Talc: 3%;

[0027] Coupling agent: 8.5%;

[0028] Lubricant: 0.5%;

[0029] Foaming aid: 1.5%;

[0030] Cross-linking agent: 0.5%;

[0031] Foaming agent: 6%.

[0032] Preferably, the PA / EBA modified blend comprises the following raw materials in percentage by mass:

[0033] PA: 45%;

[0034] Ethylene-butyl acrylate copolymer EBA: 45%;

[0035] Ethylene-acrylic acid maleic anhydride graft copolymer EAA: 9.4%;

[0036] Lubricant: 0.6%

[0037] Preferably, the TPEE / EBA modified blend comprises the following raw materials in percentage by mass:

[0038] TPEE: 45%;

[0039] Ethylene-butyl acrylate copolymer EBA: 45%;

[0040] Ethylene-acrylic acid maleic anhydride graft copolymer EAA: 9.4%;

[0041] Lubricant: 0.6%.

[0042] Furthermore, the PA is PA12 (nylon 12).

[0043] Furthermore, the TPEE is one or both of Hytrel3078 and Hytrel4056.

[0044] Preferably, the ethylene-butyl acrylate copolymer EBA is one or more combinations of EBA3427, EBA3135, EBA3217, and EBA34035.

[0045] Furthermore, the ethylene-octene copolymer POE is one or more combinations of Engage8480, Engage8450, Engage8150, and Engage8003.

[0046] Furthermore, the brominated butyl rubber is Exxon BIIR2255, and the ethylene-acrylic acid-maleic anhydride graft copolymer EAA is Fusabond A560.

[0047] Preferably, the density of the lightweight foam sole material is 0.128-0.134 g / cm 3 , hardness is 41-46C.

[0048] A method for preparing a lightweight foamed sole material comprises the following steps:

[0049] S1: PA / EBA modified blend, TPEE / EBA modified blend, ethylene-butyl acrylate copolymer EBA, ethylene-octene copolymer POE, bromobutyl rubber BIIR, coupling agent, lubricant and foaming agent are mixed according to mass percentage, poured into an internal mixer, and carried out a first stage of internal mixing. After mixing evenly, a crosslinking agent and a foaming agent are added to the internal mixer, and a second stage of internal mixing is carried out. After mixing evenly, the material is poured out of the internal mixer to obtain an internal mixing material;

[0050] S2: putting the mixed material obtained in S1 into an open mixer and performing thinning treatment at least once to obtain a uniformly mixed thinned material;

[0051] S3: The thinned material obtained in S2 is put into a granulator for granulation to obtain granules with a length of 2-3 mm;

[0052] S4: The pellets obtained in S3 are poured into a mold for primary foaming, and then subjected to secondary molding and water cooling to obtain a finished product.

[0053] Furthermore, S1 also includes the preparation of SOPA / EBA modified blends and TPEE / EBA modified blends:

[0054] Preparation of PA / EBA modified blend: PA, ethylene-butyl acrylate copolymer (EBA), ethylene-acrylic acid-maleic anhydride graft copolymer (EAA), and lubricant, calculated by mass percentage, are melt-blended in a twin-screw extruder at a temperature of 170°C-220°C to obtain a PA / EBA modified blend;

[0055] Preparation of TPEE / EBA modified blend: TPEE, ethylene-butyl acrylate copolymer EBA, ethylene-acrylic acid maleic anhydride graft copolymer EAA, and lubricant are melt-blended in a twin-screw extruder at a temperature of 150°C-190°C to obtain a TPEE / EBA modified blend.

[0056] Preferably, the temperature of the first stage of banburying in S1 is 100-105° C., and the material is turned over 3-4 times; the temperature of the second stage of banburying is 115-120° C., and the material is turned over 3-4 times.

[0057] Preferably, the thinning thickness of the open mixing mill in S2 is 2±0.5 mm.

[0058] Preferably, the expansion ratio of the rough embryo foamed once in S4 is not less than 190%.

[0059] Preferably, the temperature of the first foaming in S4 is 170-180° C., and the heating time is 400-500 seconds; the temperature of the second molding is 160-170° C., and the molding time is 450-550 seconds; and the cooling time is 450-550 seconds.

[0060] The beneficial effects of the present invention are:

[0061] Compared to traditional EVA foaming materials, EBA has better flexibility, higher thermal stability, and higher compatibility. This invention innovatively uses EBA for high-rate chemical foaming. The resulting foamed sole material has superior elasticity and flexibility compared to EVA, and can maintain better structural stability under large deformations.

[0062] The present invention also utilizes the high compatibility of EBA in combination with EAA to modify PA and TPEE, thereby improving the compatibility between PA, TPEE and various raw materials, achieving the effect of chemical foaming after the modified nylon and TPEE / EBA modified blend are blended with other raw materials, and at the same time improving the toughness and tensile resistance of nylon and TPEE.

[0063] The PA in the foamed sole material of the present invention greatly improves the material's rebound performance, and the TPEE improves the material's tear resistance, compression resistance, and rebound performance. Both have the effect of reducing the density of the foamed material and lightening its weight.

[0064] Bromobutyl rubber (BIIR) has high physical strength, good vibration damping properties, and low gas permeability. It can effectively improve the strength and airtightness of the cells of high-expansion foam materials, reduce the escape of gas within the cells, and prevent the elasticity of the foam material caused by gas escape, effectively avoiding the phenomenon of wrinkling when the product is worn. The addition of POE further enhances the elasticity of the foam material.

[0065] The foamed sole material provided by the present invention has the advantages of high elasticity, tear resistance and wrinkle resistance; the preparation method is simple, the production cost is low, and the foamed sole material has broad application prospects in the field of foamed sole materials. DETAILED DESCRIPTION

[0066] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0067] A lightweight foam sole material, comprising the following raw materials in the following mass percentages:

[0068] PA / EBA modified blend: 20% to 30%;

[0069] TPEE / EBA modified blend: 10% to 20%;

[0070] Ethylene-butyl acrylate copolymer EBA: 10% to 30%;

[0071] Ethylene-octene copolymer POE: 8% to 15%;

[0072] Bromobutyl rubber BIIR: 8% to 15%;

[0073] Talc: 2% to 3%;

[0074] Coupling agent: 5% to 10%;

[0075] Lubricant: 0.5% to 1%;

[0076] Foaming aid: 1% to 2%;

[0077] Cross-linking agent: 0.3% to 1%;

[0078] Foaming agent: 3%~7%.

[0079] The PA / EBA modified blend includes the following raw materials in percentage by mass:

[0080] PA: 45%;

[0081] Ethylene-butyl acrylate copolymer EBA: 45%;

[0082] Ethylene-acrylic acid maleic anhydride graft copolymer EAA: 9.4%;

[0083] Lubricant: 0.6%.

[0084] The TPEE / EBA modified blend includes the following raw materials in percentage by mass:

[0085] TPEE: 45%;

[0086] Ethylene-butyl acrylate copolymer EBA: 45%;

[0087] Ethylene-acrylic acid maleic anhydride graft copolymer EAA: 9.4%;

[0088] Lubricant: 0.6%.

[0089] A lightweight foamed sole material, wherein the PA is PA12 (nylon 12). Nylon, a polymer composed of amide groups and methylene groups, contains polar amide groups in the repeating units of its molecular backbone, which can form intermolecular hydrogen bonds and have strong intermolecular interaction forces, resulting in high mechanical strength and modulus. Furthermore, the methylene groups on its molecular backbone have a certain degree of flexibility, allowing the molecular chain to rotate and move freely to a certain extent. This allows the nylon molecular chain to more effectively transmit stress when stretched, exhibiting excellent elasticity, while also reducing the density of the foam material and lightening its weight.

[0090] A lightweight foam sole material, wherein the TPEE is one or both of Hytrel 3078 and Hytrel 4056. TPEE combines the excellent elasticity of rubber with the processability of thermoplastics, offering adjustable hardness and design flexibility. It significantly improves the material's tear resistance, compression resistance, and resilience, while also reducing the density of the foam material and weight.

[0091] A lightweight foam sole material, wherein the ethylene-butyl acrylate copolymer (EBA) is one or more of EBA3427, EBA3135, EBA3217, and EBA34035. EBA is an ethylene-butyl acrylate copolymer. The ethylene in its molecular structure provides EBA's crystallinity and hardness, while the butyl acrylate provides flexibility.

[0092] A lightweight foamed sole material, wherein the ethylene-octene copolymer (POE) is one or more combinations of Engage 8480, Engage 8450, Engage 8150, and Engage 8003. As an ethylene-octene copolymer, POE has good elasticity and flexibility, further improving the elasticity of the foamed material.

[0093] A lightweight foam sole material, comprising Exxon BIIR2255 bromobutyl rubber and Fusabond A560 ethylene acrylic acid-maleic anhydride graft copolymer (EAA). Bromobutyl rubber has a substantially saturated main chain similar to butyl rubber, resulting in high physical strength, good vibration damping properties, and low gas permeability.

[0094] A lightweight foamed sole material, wherein the coupling agent is a silane coupling agent, the silane coupling agent is MT-5400 (Xiamen United Xinnuo New Materials Co., Ltd.), the lubricant is stearic acid ST, the foaming aid is zinc oxide ZnO, the cross-linking agent is 1,4-bis-tert-butylperoxyisopropylbenzene BIPB, and the foaming agent is azodicarbonamide AC6000H.

[0095] A method for preparing a lightweight foamed sole material comprises the following steps:

[0096] Preparation of SOPA / EBA modified blends and TPEE / EBA modified blends:

[0097] Preparation of PA / EBA modified blend: PA, ethylene-butyl acrylate copolymer (EBA), ethylene-acrylic acid-maleic anhydride graft copolymer (EAA), and lubricant, calculated by mass percentage, are melt-blended in a twin-screw extruder at a temperature of 170°C-220°C to obtain a PA / EBA modified blend;

[0098] Preparation of TPEE / EBA modified blend: TPEE, ethylene-butyl acrylate copolymer (EBA), ethylene-acrylic acid-maleic anhydride graft copolymer (EAA), and lubricant, calculated by mass percentage, are melt-blended in a twin-screw extruder at a temperature of 150°C-190°C to obtain a TPEE / EBA modified blend;

[0099] S1: PA / EBA modified blend, TPEE / EBA modified blend, ethylene-butyl acrylate copolymer EBA, ethylene-octene copolymer POE, bromobutyl rubber BIIR, coupling agent, lubricant and foaming aid are mixed according to mass percentage, poured into an internal mixer, and subjected to first-stage internal mixing at a temperature of 100-105° C. and the material is turned over 3-4 times; after mixing evenly, a crosslinking agent and a foaming agent are added into the internal mixer; a second-stage internal mixing is carried out at a temperature of 115-120° C. and the material is turned over 3-4 times; after mixing evenly, the material is poured out of the internal mixer to obtain a mixed material;

[0100] S2: The mixed material obtained in S1 is placed in an open mixer and thinned at least once. The thinning thickness of the open mixer is 2±0.5 mm to obtain a uniformly mixed thinned material.

[0101] S3: The thinned material obtained in S2 is put into a granulator for granulation to obtain granules with a length of 2-3 mm;

[0102] S4: Pour the pellets obtained in S3 into a mold for primary foaming. The primary foaming temperature is 170-180°C, the heating time is 400-500 seconds, and the foaming ratio of the primary foamed rough embryo is 195%. Then, the pellets are water-cooled after secondary molding. The secondary molding temperature is 160-170°C, the molding time is 450-550 seconds, and the cooling time is 450-550 seconds to obtain a finished product.

[0103] A lightweight foamed sole material is provided. Examples 1-3 and Comparative Examples 1-6 are prepared, by weight percentage, from the formulations shown in Table 1 using the above-described preparation method. The PA / EBA modified blend is prepared by melt blending 45% PA12, 45% EBA3427, 9.4% ethylene-acrylic acid-maleic anhydride graft copolymer (EAA), and 0.6% stearic acid (ST); and the TPEE / EBA modified blend is prepared by melt blending 45% Hytrel 4056, 45% EBA3427, 9.4% ethylene-acrylic acid-maleic anhydride graft copolymer (EAA), and 0.6% stearic acid (ST).

[0104] Table 1 - Foam sole material formula Table 1

[0105]

[0106]

[0107] Example 4

[0108] A lightweight foam sole material is prepared by the above-mentioned preparation method according to the formula shown in Table 2, calculated by mass percentage; wherein the PA / EBA modified blend is prepared by melt blending 45% PA12, 45% EBA3125, 9.4% ethylene-acrylic acid maleic anhydride graft copolymer EAA, and 0.6% stearic acid ST; and the TPEE / EBA modified blend is prepared by melt blending 45% Hytrel4056, 45% EBA3135, 9.4% ethylene-acrylic acid maleic anhydride graft copolymer EAA, and 0.6% stearic acid ST.

[0109] Table 2 - Foam sole material formula Table 2

[0110]

[0111] Example 5

[0112] A lightweight foam sole material is prepared by the above-mentioned preparation method according to the formula shown in Table 3, calculated by mass percentage; wherein the PA / EBA modified blend is prepared by melt blending 45% PA12, 45% EBA34035, 9.4% ethylene-acrylic acid maleic anhydride graft copolymer EAA, and 0.6% stearic acid ST; and the TPEE / EBA modified blend is prepared by melt blending 45% Hytrel4056, 45% EBA34035, 9.4% ethylene-acrylic acid maleic anhydride graft copolymer EAA, and 0.6% stearic acid ST.

[0113] Table 3 - Foam sole material formula Table 3

[0114]

[0115]

[0116] Example 6

[0117] A lightweight foam sole material is prepared by the above-mentioned preparation method according to the formula shown in Table 3, calculated by mass percentage; wherein the PA / EBA modified blend is prepared by melt blending 45% PA12, 45% EBA3427, 9.4% ethylene-acrylic acid maleic anhydride graft copolymer EAA, and 0.6% stearic acid ST; and the TPEE / EBA modified blend is prepared by melt blending 45% Hytrel4056, 45% EBA3427, 9.4% ethylene-acrylic acid maleic anhydride graft copolymer EAA, and 0.6% stearic acid ST.

[0118] Table 4 - Foam sole material formula Table 4

[0119]

[0120] The sole samples of Examples 1-6 and Comparative Examples 1-6 were tested for hardness (GB / T3903.4-2017), density (GB / T533-2008), rebound (GB / T1681-2009), thermal shrinkage (HG / T2874-1997), compression deformation (HG / T2876-2009), wear resistance (GB / T3903.2-2017), C-type tear (GB / T529-2008), tensile strength (GB / T528-2009), elongation at break (GB / T528-2009), and shock absorption performance (GB / T30907-2014). The test results are shown in Tables 5 and 6.

[0121] Table 5 Performance test results of the sole samples obtained in Examples 1-6

[0122] Test items Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Hardness C 44 45 46 41 43 44 Density g / cm3 0.13 0.133 0.128 0.133 0.131 0.134 elasticity% 65 67 65 67 67 67 shrink% 0.7 0.5 0.6 0.9 0.9 0.7 Compression deformation% 35 32 34 35 36 34 Wear resistance mm 11.7 11.5 12 12.4 12.3 12.0 C-type tear kg / cm 11.6 13.3 12.2 10.3 10.7 11.7 Tensile strength MPa 2.0 2.4 2.1 1.9 2.0 2.1 Elongation at break % 255 294 262 274 275 280 Shock absorption performance G value % 9.6 9.4 9.7 9.9 9.8 9.7

[0123] Table 6 Performance test results of the sole samples obtained in Comparative Examples 1-6

[0124] Test items Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Hardness C / 44 45 45 35 35 Density g / cm3 / 0.13 0.132 0.135 0.131 0.132 elasticity% / 64 60 63 55 52 shrink% / 0.6 0.8 0.8 1.6 2.6 Compression deformation% / 36 34 36 41 44 Wear resistance mm / 12.1 11.9 11.8 13.1 13.2 C-type tear kg / cm / 10.3 12.4 11.7 8.9 7.8 Tensile strength MPa / 1.9 2.3 2.1 1.7 1.5 Elongation at break % / 248 276 271 223 202 Shock absorption performance G value % / 9.8 9.5 10.4 12.4 12.2

[0125] The formulas in Examples 1-6 can all be foamed normally through a secondary molding high-ratio chemical foaming process, with the rough embryo small foaming ratio reaching 195%, resulting in a high-ratio, low-density chemical foaming material. The resulting foamed sole material has high cell strength and strong sealing properties, effectively maintaining product elasticity, thereby effectively alleviating the problem of wrinkling during wear. In addition, the production process is simple, the production defect rate is low, and the production cost is low. The density of the resulting lightweight foamed sole material is 0.128-0.134g / cm 3 , hardness is 41-46C, elasticity ≥65%.

[0126] The performance test results in Tables 5 and 6 indicate that Example 2 is the preferred formulation, exhibiting the best operational performance and the most excellent overall physical properties. The sole made from the foamed product of Example 2 exhibits advantages such as strong support, high rebound, excellent shock absorption, excellent dimensional stability, and excellent deformation resistance. The product is lighter, more resilient, and more comfortable, making it an ideal, high-quality shoe material.

[0127] Combining the performance test results in Tables 5 and 6, Examples 1-3 demonstrate that a higher total amount of PA / EBA and TPEE / EBA modified blends in a formulation does not necessarily improve physical properties. Comparative Example 1 lacks EBA, resulting in a material that fails to foam. Comparative Example 2, using the PA / EBA modified blend alone for foaming, yields a foamed material with good elasticity but insufficient tear and tensile properties. Comparative Example 3, using the TPEE / EBA modified blend alone for foaming, exhibits good tear resistance and compression set, but limited improvement in the finished product's elasticity. These results demonstrate that when the two modified blends are combined with EBA in appropriate proportions for foaming, the resulting sole foam material exhibits lightweight, high elasticity, tear resistance, and deformation resistance.

[0128] In Comparative Example 4, no brominated butyl rubber BIIR was added, and the elasticity and deformation resistance of the obtained foamed material decreased. This was mainly because BIIR could effectively improve the gas barrier performance of the internal cells of the foamed material, and prevent the material elasticity from attenuating, wrinkling, and deformation caused by gas escape and cell shrinkage. In the formulas of Comparative Examples 5 and 6, PA / EBA modified blends or TPEE / EBA modified blends were not used, and the elasticity, tear resistance, deformation resistance and other properties of the products obtained by the high-ratio foaming process did not meet the ideal requirements.

[0129] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A lightweight foam sole material, characterized in that: The invention comprises the following raw materials in percentage by weight: PA / EBA modified blend: 20% to 30%; TPEE / EBA modified blend: 10% to 20%; Ethylene-butyl acrylate copolymer EBA: 10% to 30%; Ethylene-octene copolymer POE: 8% to 15%; Bromobutyl rubber BIIR: 8% to 15%; Talc: 2% to 3%; Coupling agent: 5% to 10%; Lubricant: 0.5% to 1%; Foaming aid: 1% to 2%; Cross-linking agent: 0.3% to 1%; Foaming agent: 3%~7%.

2. A lightweight foam sole material according to claim 1, characterized in that: The PA / EBA modified blend includes the following raw materials in percentage by mass: PA: 45%; Ethylene-butyl acrylate copolymer EBA: 45%; Ethylene-acrylic acid maleic anhydride graft copolymer EAA: 9.4%; Lubricant: 0.6%.

3. The lightweight foam sole material according to claim 1, characterized in that: The TPEE / EBA modified blend includes the following raw materials in percentage by mass: TPEE: 45%; Ethylene-butyl acrylate copolymer EBA: 45%; Ethylene-acrylic acid maleic anhydride graft copolymer EAA: 9.4%; Lubricant: 0.6%.

4. A lightweight foam sole material according to claims 1-3, characterized in that: The ethylene-butyl acrylate copolymer EBA is one or more combinations of EBA3427, EBA3135, EBA3217, and EBA34035.

5. A lightweight foam sole material according to any one of claims 1 to 3, characterized in that: The density of the lightweight foam sole material is 0.128-0.134 g / cm 3 , hardness is 41-46C.

6. A method for preparing a lightweight foamed sole material according to any one of claims 1 to 3, comprising the following steps: S1: PA / EBA modified blend, TPEE / EBA modified blend, ethylene-butyl acrylate copolymer EBA, ethylene-octene copolymer POE, bromobutyl rubber BIIR, coupling agent, lubricant and foaming agent are mixed according to mass percentage, poured into an internal mixer, and carried out a first stage of internal mixing. After mixing evenly, a crosslinking agent and a foaming agent are added to the internal mixer, and a second stage of internal mixing is carried out. After mixing evenly, the material is poured out of the internal mixer to obtain an internal mixing material; S2: putting the mixed material obtained in S1 into an open mixer and performing thinning treatment at least once to obtain a uniformly mixed thinned material; S3: The thinned material obtained in S2 is put into a granulator for granulation to obtain granules with a length of 2-3 mm; S4: The pellets obtained in S3 are poured into a mold for primary foaming, and then subjected to secondary molding and water cooling to obtain a finished product.

7. The method for preparing a lightweight foamed sole material according to claim 6, characterized in that: In S1, the temperature of the first stage of internal mixing is 100-105°C, and the material is turned over 3-4 times; the temperature of the second stage of internal mixing is 115-120°C, and the material is turned over 3-4 times.

8. The method for preparing a lightweight foamed sole material according to claim 6, wherein: The thinning thickness of the open mixing mill in S2 is 2±0.5mm.

9. The method for preparing a lightweight foamed sole material according to claim 6, wherein: The expansion ratio of the rough embryo foamed once in S4 is not less than 190%.

10. The method for preparing a lightweight foamed sole material according to claim 6, characterized in that: In S4, the temperature of the first foaming is 170-180° C., and the heating time is 400-500 seconds; the temperature of the second molding is 160-170° C., and the molding time is 450-550 seconds; and the cooling time is 450-550 seconds.

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