Lightweight pu foamed sole and method of making same

Abstract

The application discloses a kind of light PU foamed soles and preparation method thereof, belong to foamed sole technical field, the sole is significantly improved shock absorption and folding resistance by optimizing material formula and preparation process.The sole is composed of ethylene-vinyl acetate copolymer, ethylene octene copolymer, SBS thermoplastic elastomer, polyether polyurethane and other raw materials, and introduces specific shock absorbing additive.Preparation method includes steps such as banxie, mixing, foaming forming, by accurately controlling temperature, time and turning over times, ensure the uniform mixing of material and the full performance of crosslinking reaction.Compared with prior art, the sole of the application is outstanding in shock absorption and folding resistance, and has important practical application value and market prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of foaming shoe soles, and particularly relates to a light-weight PU foaming shoe sole and a preparation method thereof. BACKGROUND

[0002] In the technical field of foaming shoe soles, especially in the preparation of light-weight PU foaming shoe soles, shock absorption and bending resistance are key indicators to measure the quality of shoe soles. Although existing light-weight foaming shoe sole technology meets the market demand for lightness and comfort to some extent, there are still obvious deficiencies in high-performance application scenarios.

[0003] In the prior art, light-weight foaming shoe soles have limited performance in absorbing impact energy. For example, some traditional foaming materials are prone to uneven energy transmission under high-energy impact, resulting in poor shock absorption effect. This problem is particularly prominent in scenarios such as sports shoes and work shoes that require high-strength shock absorption. In addition, traditional foaming shoe sole materials are prone to fatigue after multiple impacts, and the shock absorption performance gradually decreases, affecting the service life and wearing experience of the shoe sole. In terms of bending resistance, existing foaming shoe soles are prone to cracking or breaking during repeated bending, especially in the forefoot and heel parts of the shoe sole. These parts bear the most bending stress during walking and movement, and insufficient bending resistance will cause the shoe sole to be damaged prematurely, affecting the overall quality and service life of the shoe. Some foaming materials have further decreased bending resistance in high-temperature or humid environments, limiting their application in complex environments.

[0004] The limitations of existing technology mainly lie in the material formula and preparation process. Although various additives have been added to traditional material formulas to improve performance, there is still a lot of room for improvement in shock absorption and bending resistance. For example, commonly used fillers and cross-linking agents often sacrifice flexibility and elasticity while improving material strength. In addition, existing preparation processes have deficiencies in mixing uniformity and control of cross-linking reactions. For example, the temperature and time control in the mixing and mixing process is not precise enough, resulting in unevenness of material performance. Traditional freeze-drying technology is less used in the preparation of shock-absorbing additives, limiting the further improvement of shock-absorbing performance.

[0005] Chinese patent publication No. CN114891292A discloses a light oil-resistant antiskid foamed shoe sole and its preparation process. The shoe sole is composed of ethylene-vinyl acetate copolymer, maleic anhydride grafted EVA, nitrile rubber, SBS thermoplastic elastomer, foaming agent, accelerator, crosslinking agent, nano filler (composed of attapulgite, asbestos fiber, mica powder in a specific ratio), zinc stearate and naphthenic oil. By combining ethylene-vinyl acetate copolymer, nitrile rubber and SBS thermoplastic elastomer, and introducing maleic anhydride grafted EVA to enhance the compatibility and adhesion between the raw materials, the invention successfully improves the oil resistance and slip resistance of the foamed shoe sole, while ensuring the overall mechanical properties of the shoe sole. However, despite the significant progress in oil resistance and slip resistance, the light oil-resistant antiskid foamed shoe sole prepared by this patent still needs to be further improved in terms of shock absorption and folding resistance.

[0006] In summary, the shortcomings of the prior art in shock absorption and folding resistance limit the application of light foamed shoe soles in high-performance application scenarios. Therefore, it is of great practical significance and market value to develop a light PU foamed shoe sole with excellent shock absorption and folding resistance performance and its preparation method. SUMMARY

[0007] In order to solve the shortcomings of the prior art, the present invention aims to provide a light PU foamed shoe sole and its preparation method.

[0008] In order to achieve the above invention purpose, the present invention adopts the following technical solution:

[0009] A light PU foamed shoe sole, comprising the following raw materials by weight:

[0010] 15-25 parts of ethylene-vinyl acetate copolymer, 10-20 parts of ethylene octene copolymer, 5-10 parts of SBS thermoplastic elastomer, 5-15 parts of polyether polyurethane, 4-6 parts of kaolin, 0.5-1 part of calcium stearate, 2-4 parts of paraffin oil, 0.5-2 parts of azodicarbonamide, 1-2 parts of shock absorption additive, 0.5-1 part of dimethyl silicone oil, 0.5-1 part of di-t-butyl peroxide.

[0011] The preparation method of the shock absorption additive comprises the following steps: mixing an organic silicon compound with a functional organic silane, adding water, heating and stirring to obtain a pretreatment; then dissolving polyacrylamide in water, heating and stirring uniformly to prepare an active solution; then adding talcum powder, bentonite, boron oxide and ammonium dihydrogen phosphate into water to form a suspension; then adding the active solution dropwise into the pretreatment, continuing to stir, and mixing uniformly with the suspension; finally, freeze-drying to obtain the shock absorption additive.

[0012] A preparation method of a light PU foamed shoe sole is as follows, in parts by weight:

[0013] Step 1, 15~25 parts of ethylene-vinyl acetate copolymer, 10~20 parts of ethylene octene copolymer, 5~10 parts of SBS thermoplastic elastomer, 5~15 parts of polyether polyurethane are mixed into an internal mixer, and mixed for 8~12 minutes, then 4~6 parts of kaolin, 0.5~1 parts of calcium stearate, 2~4 parts of paraffin oil are added and mixed, when the temperature of the internal mixer reaches 90~100℃, keep for 3~5 minutes, then do the first turning, when the temperature of the internal mixer reaches 95~105℃, do the second turning, when the temperature of the internal mixer reaches 100~110℃, do the third turning, when the temperature of the internal mixer reaches 105~115℃, do the fourth turning, when the temperature of the internal mixer reaches 110~120℃, do the fifth turning, then mix for 2~4 minutes, discharge, and keep at room temperature for 10~48 hours to obtain a mixture;

[0014] Step 2, the mixture prepared in step 1 is added to a two-roll open mill, then 0.5~2 parts of azodicarbonamide, 1~2 parts of shock-absorbing additive, 0.5~1 parts of dimethyl silicone oil, 0.5~1 parts of di-t-butyl peroxide are added and mixed, then the mixed material is made into a sheet;

[0015] Step 3, the sheet prepared in step 2 is cut into the shape of a shoe sole and put into a shoe sole mold for foaming and molding, then naturally cooled to room temperature to obtain a light-weight PU foamed shoe sole.

[0016] The temperature of the internal mixer in step 1 is increased at a speed of 1~2℃ / min.

[0017] The mixing temperature in step 2 is 100~130℃, and the time is 5~15 minutes.

[0018] The thickness of the sheet in step 2 is controlled to be 2~4mm.

[0019] The foaming temperature in step 3 is 130~170℃.

[0020] The shock-absorbing additive is prepared as follows, by weight:

[0021] The pre-treatment is prepared by mixing 15-25 parts of the organosilicon compound and 5-10 parts of the functional organosilane in 120-180 parts of water, continuously stirring at 70-80℃ for 2-5 hours; the active solution is prepared by dissolving 10-20 parts of polyacrylamide in 200-400 parts of water, heating to 65-75℃ and stirring until uniform; then 5-10 parts of talc, 2-6 parts of bentonite, 4-8 parts of boron oxide and 4-6 parts of ammonium dihydrogen phosphate are mixed in 100-150 parts of water to form a suspension, and the active solution is added dropwise to the pre-treatment at a rate of 10-30 mL / min, continuously stirring at 70-90℃ for 1-3 hours, then mixing uniformly with the suspension, and freeze-drying to obtain the shock-absorbing additive.

[0022] The organosilicon compound is at least one of tetramethoxysilane, tetra-sec-butoxysilane, bis(3-trimethoxysilylpropyl)amine, and bis-[3-(triethoxysilyl)propyl]-tetrasulfide.

[0023] The functional organosilane is at least one of 3-glycidyloxypropylmethyldiethoxysilane and 1-(3-glycidylpropyl)-1,1,3,3,3-pentaethoxy-1,3-disilapropyl.

[0024] The organosilicon compound forms a silica network through hydrolysis and condensation reactions in the shock-absorbing additive, providing a high-strength and thermally stable skeleton for the shock-absorbing additive, enhancing the overall mechanical properties, and maintaining stability at high temperatures.

[0025] The functional organosilane forms a complex three-dimensional network structure through cross-linking reactions with other components via its reactive groups, further enhancing the toughness and elasticity of the material and improving the shock-absorbing performance.

[0026] As a cross-linking agent, polyacrylamide forms an active solution in water that can cross-link with the organosilicon compound and the functional organosilane, forming a uniform and tight network structure that significantly improves the elasticity and toughness of the shock-absorbing additive, while also improving the water absorption and biocompatibility of the material.

[0027] Talc, as an inorganic filler, can significantly improve the mechanical properties and thermal stability of the shock-absorbing additive. Its lamellar structure forms a physical barrier in the material, enhancing toughness and tear resistance, while reducing material costs and maintaining good processing performance.

[0028] Bentonite has good adsorption and swelling properties, forming a uniform distribution of microporous structures in the shock-absorbing additive, effectively absorbing and dispersing impact energy, improving shock-absorbing performance, while enhancing the flexibility and fatigue resistance of the material.

[0029] Boron oxide can reduce the melting point and viscosity of the material, promote the hydrolysis and condensation reaction of organosilicon compounds and functional organosilanes, and form a stable network structure at a lower temperature, while enhancing thermal stability and chemical stability.

[0030] Ammonium dihydrogen phosphate can adjust the pH value of the material, ensure that the reaction is carried out under suitable acid-base conditions, improve the reaction efficiency and uniformity, and further enhance the network structure, improve the mechanical properties and thermal stability.

[0031] The synergistic effect of these substances enables the shock-absorbing additive to significantly improve the shock-absorbing performance and folding resistance of the sole, meeting the demand for high-performance soles.

[0032] Compared with the prior art, the following benefits are achieved:

[0033] 1) The lightweight PU foamed sole of the present application performs well in absorbing impact energy. The organosilicon compounds and functional organosilanes in the shock-absorbing additive can form a complex cross-linked network, effectively dispersing impact force, thereby significantly improving the shock-absorbing effect of the sole.

[0034] 2) The sole of the present application can still maintain good structural integrity during repeated bending. The flexible structure and high-density cross-linked network in the shock-absorbing additive endow the sole with excellent elasticity and folding resistance, effectively prolonging the service life of the sole.

[0035] 3) The preparation method of the present application precisely controls the temperature, time and turning frequency during the mixing and mixing process, ensuring uniform mixing of the material and sufficient cross-linking reaction. In addition, the application of freeze-drying technology further improves the quality of the shock-absorbing additive, making its dispersion in the sole more uniform, thereby improving the overall performance of the sole. This optimized preparation process not only improves production efficiency, but also reduces production cost, and has good industrial application prospect. BRIEF DESCRIPTION OF DRAWINGS DETAILED DESCRIPTION

[0036] Main material sources:

[0037] Ethylene-vinyl acetate copolymer, brand: 7470M, manufacturer (place of origin): Taiwan Plastics.

[0038] Ethylene-octene block copolymer, specification: 8003, brand: Dow Chemical, USA.

[0039] SBS thermoplastic elastomer, brand: D1101JO, manufacturer (place of origin): Kortec, USA.

[0040] Polyether polyurethane, item number: TPU 1185A, brand: BASF, Germany.

[0041] Kaolin, 800 mesh.

[0042] Paraffin oil, item number: 6-17, Chuangyi Da (Shandong) Biological Technology Co., Ltd.

[0043] Dimethyl silicone oil, model number: 1PMX-200, brand: Dow Corning.

[0044] Polyacrylamide, mesh number: 60-80, item number: 05, Henan Chuanyihuanbao Technology Co., Ltd.

[0045] Talc, 1250 mesh.

[0046] Bentonite, 800 mesh.

[0047] Boron oxide, specification: 1um.

[0048] The remaining raw materials in the examples and comparative examples of the present application are commercially available products.

[0049] The design idea of the present application is to optimize the formula and preparation process of the shoe sole material, and to develop a lightweight PU foaming shoe sole with excellent shock absorption performance and bending resistance. The core is to introduce a specific shock absorbing additive, and its preparation process involves the mixing of organosilicon compounds and functional organosilane, the activation of polyacrylamide and the synergistic effect of various inorganic fillers. This shock absorbing additive can significantly improve the structural stability of the shoe sole when absorbing impact energy and repeated bending, thereby meeting the needs of high-performance shoe soles.

[0050] Example 1

[0051] A method for preparing a lightweight PU foaming shoe sole is as follows, in parts by weight:

[0052] Step 1, mix 20 parts of ethylene-vinyl acetate copolymer, 15 parts of ethylene octene copolymer, 8 parts of SBS thermoplastic elastomer, and 10 parts of polyether polyurethane in an internal mixer, and mix for 10 minutes, with the temperature rising speed of the internal mixer being 1.5℃ / min, then add 5 parts of kaolin, 0.8 parts of calcium stearate, and 3 parts of paraffin oil, continue to mix and mix, when the mixing temperature reaches 95℃, keep for 4 minutes, then perform a turnover, when the mixing temperature rises to 100℃, perform a second turnover, when the mixing temperature rises to 105℃, perform a third turnover, when the mixing temperature rises to 110℃, perform a fourth turnover, when the mixing temperature rises to 115℃, perform a fifth turnover, then mix for another 3 minutes, discharge the glue, and place at room temperature for 24 hours to obtain a mixture;

[0053] Step 2, the mixture prepared in step 1 is added to a two-roll open mill, then 1 part of azodicarbonamide, 1.5 parts of shock-absorbing additive, 0.8 parts of dimethyl silicone oil, 0.8 parts of di-tert-butyl peroxide are added for mixing, the mixing temperature is 110℃, the mixing time is 10 minutes, the mixed material is uniformly mixed, and the uniformly mixed material is made into a sheet with a thickness of 3mm;

[0054] Step 3, the sheet prepared in step 2 is cut into the shape of a shoe sole and placed in a shoe sole mold for foaming and molding, the foaming temperature is 160℃, after foaming is completed, natural cooling is performed to room temperature, and a light PU foamed shoe sole is obtained.

[0055] The preparation method of the shock-absorbing additive is as follows, in terms of weight parts:

[0056] After 20 parts of bis(3-trimethoxysilylpropyl)amine and 8 parts of 1-(3-glycidyl ether propyl)-1,1,3,3,3-pentaethoxy-1,3-disilane are mixed, they are added to 150 parts of water, and stirring is continuously performed at a temperature of 75℃ for 3 hours, thereby preparing a pretreatment; 15 parts of polyacrylamide is dissolved in 300 parts of water, heated to 70℃ and uniformly stirred to prepare an active solution; then 8 parts of talc, 4 parts of bentonite, 6 parts of boron oxide and 5 parts of ammonium dihydrogen phosphate are added to 120 parts of water to form a suspension, the active solution is added dropwise to the pretreatment, the dropping speed is 20mL / min, and stirring is continuously performed at a temperature of 80℃ for 1.5 hours, then the suspension is uniformly mixed, and freeze-drying is performed, thereby obtaining the shock-absorbing additive.

[0057] Example 2

[0058] A preparation method of a light PU foamed shoe sole is basically the same as that in example 1, and the only difference is that the preparation method of the shock-absorbing additive is different.

[0059] The preparation method of the shock-absorbing additive is as follows, in terms of weight parts:

[0060] After 20 parts of bis(3-trimethoxysilylpropyl)amine and 8 parts of 1-(3-glycidyl ether propyl)-1,1,3,3,3-pentaethoxy-1,3-disilane are mixed, they are added to 150 parts of water, and stirring is continuously performed at a temperature of 75℃ for 3 hours, thereby preparing a pretreatment; 15 parts of polyacrylamide is dissolved in 300 parts of water, heated to 70℃ and uniformly stirred to prepare an active solution; then 8 parts of talc, 4 parts of bentonite, 6 parts of boron oxide and 5 parts of ammonium dihydrogen phosphate are added to 120 parts of water to form a suspension, the active solution is added dropwise to the pretreatment, the dropping speed is 20mL / min, and stirring is continuously performed at a temperature of 80℃ for 1.5 hours, then the suspension is uniformly mixed, and freeze-drying is performed, thereby obtaining the shock-absorbing additive.

[0061] Example 3

[0062] A method for preparing a light PU foamed shoe sole is basically the same as that in Embodiment 1, except that the method for preparing the shock-absorbing additive is different.

[0063] The method for preparing the shock-absorbing additive is as follows, in terms of weight parts:

[0064] After 20 parts of tetramethoxysilane and 8 parts of 1-(3-glycidyloxypropyl)-1,1,3,3,3-pentaethoxy-1,3-disilapropyl silane are mixed, they are added to 150 parts of water, and stirring is continued at a temperature of 75°C for 3 hours, thereby preparing a pretreatment; 15 parts of polyacrylamide are dissolved in 300 parts of water, heated to 70°C and stirred uniformly, to prepare an active solution; then 8 parts of talc, 4 parts of bentonite, 6 parts of boron oxide and 5 parts of ammonium dihydrogen phosphate are mixed in 120 parts of water to form a suspension, and the active solution is added dropwise to the pretreatment at a dropwise adding speed of 20 mL / min, and stirring is continued at a temperature of 80°C for 1.5 hours, and then mixed uniformly with the suspension, and freeze-dried, to obtain the shock-absorbing additive.

[0065] Embodiment 4

[0066] A method for preparing a light PU foamed shoe sole is basically the same as that in Embodiment 1, except that the method for preparing the shock-absorbing additive is different.

[0067] The method for preparing the shock-absorbing additive is as follows, in terms of weight parts:

[0068] After 20 parts of tetramethoxysilane and 8 parts of 1-(3-glycidyloxypropyl)-1,1,3,3,3-pentaethoxy-1,3-disilapropyl silane are mixed, they are added to 150 parts of water, and stirring is continued at a temperature of 75°C for 3 hours, thereby preparing a pretreatment; 15 parts of polyacrylamide are dissolved in 300 parts of water, heated to 70°C and stirred uniformly, to prepare an active solution; then 8 parts of talc, 4 parts of bentonite, 6 parts of boron oxide and 5 parts of ammonium dihydrogen phosphate are mixed in 120 parts of water to form a suspension, and the active solution is added dropwise to the pretreatment at a dropwise adding speed of 20 mL / min, and stirring is continued at a temperature of 80°C for 1.5 hours, and then mixed uniformly with the suspension, and freeze-dried, to obtain the shock-absorbing additive.

[0069] Embodiment 5

[0070] A method for preparing a light PU foamed shoe sole is basically the same as that in Embodiment 1, except that the method for preparing the shock-absorbing additive is different.

[0071] The method for preparing the shock-absorbing additive is as follows, in terms of weight parts:

[0072] Twenty parts of bis-[3-(triethoxysilyl)propyl]-tetrasulfide and eight parts of 1-(3-glycidyl ether propyl)-1,1,3,3,3-pentaethoxy-1,3-disilpropane were mixed and added to 150 parts of water. The mixture was stirred continuously at 75°C for 3 hours to obtain a pretreated material. Fifteen parts of polyacrylamide were dissolved in 300 parts of water, heated to 70°C and stirred until homogeneous to prepare an active solution. Eight parts of talc, four parts of bentonite, six parts of boron oxide and five parts of ammonium dihydrogen phosphate were added to 120 parts of water to form a suspension. The active solution was added dropwise to the pretreated material at a rate of 20 mL / min. The mixture was stirred continuously at 80°C for 1.5 hours, then mixed evenly with the suspension and freeze-dried to obtain a shock-absorbing additive.

[0073] Comparative Example 1

[0074] The preparation method of a lightweight PU foam shoe sole is basically the same as that in Example 1, except that the preparation method of the shock-absorbing additive is different.

[0075] The preparation method of the shock-absorbing additive is as follows, in parts by weight:

[0076] 20 parts of propyl orthosilicate and 8 parts of 1-(3-glycidyl ether propyl)-1,1,3,3,3-pentaethoxy-1,3-disilpropane were mixed and added to 150 parts of water. The mixture was stirred continuously at 75°C for 3 hours to obtain a pretreated material. 15 parts of polyacrylamide were dissolved in 300 parts of water, heated to 70°C and stirred evenly to prepare an active solution. Then, 8 parts of talc, 4 parts of bentonite, 6 parts of boron oxide and 5 parts of ammonium dihydrogen phosphate were added to 120 parts of water to form a suspension. The active solution was added dropwise to the pretreated material at a rate of 20 mL / min. The mixture was stirred continuously at 80°C for 1.5 hours, then mixed evenly with the suspension and freeze-dried to obtain a shock-absorbing additive.

[0077] Comparative Example 2

[0078] The preparation method of a lightweight PU foam shoe sole is basically the same as that in Example 1, except that the preparation method of the shock-absorbing additive is different.

[0079] The preparation method of the shock-absorbing additive is as follows, in parts by weight:

[0080] 20 parts of di(3-trimethoxysilylpropyl)amine and 8 parts of 3-[(2,3)-epoxypropoxy]propylmethyldimethoxysilane were mixed and added to 150 parts of water. The mixture was stirred continuously at 75°C for 3 hours to obtain a pretreated material. 15 parts of polyacrylamide were dissolved in 300 parts of water, heated to 70°C and stirred evenly to prepare an active solution. Then, 8 parts of talc, 4 parts of bentonite, 6 parts of boron oxide and 5 parts of ammonium dihydrogen phosphate were added to 120 parts of water to form a suspension. The active solution was added dropwise to the pretreated material at a rate of 20 mL / min. The mixture was stirred continuously at 80°C for 1.5 hours, then mixed evenly with the suspension and freeze-dried to obtain a shock-absorbing additive.

[0081] Comparative Example 3

[0082] The preparation method of a lightweight PU foam shoe sole is basically the same as that in Example 1, except that the shock-absorbing additive is not added.

[0083] Test Example 1

[0084] Vibration damping performance test

[0085] The shock absorption performance of the soles of Examples 1-5 and Comparative Examples 1-3 was tested according to the method described in GB / T 30907-2014 "Test Method for Shock Absorption Performance of Rubber Shoes and Sports Shoes". The test part was the heel, and 7J of energy was applied to the sole. The test results are shown in Table 1.

[0086] Table 1

[0087] Experimental protocol Damping performance (G value) Example 1 13.7 Example 2 14.5 Example 3 14.8 Example 4 14.9 Example 5 13.7 Comparative Example 1 15.6 Comparative Example 2 15.0 Comparative Example 3 19.8

[0088] Test Example 2

[0089] Flexural endurance test

[0090] The soles of Examples 1-5 and Comparative Examples 1-3 were tested according to the methods specified in GB / T 3903.1-2017 "Test Methods for Flexural Resistance of Whole Footwear". Test conditions: flexure angle: 50°, flexure frequency: 230 times / minute, number of flexures: 40,000, cut length: 5mm. The test results are shown in Table 2.

[0091] Table 2

[0092] Experimental protocol Crack length mm Example 1 6.2 Example 2 6.9 Example 3 7.4 Example 4 7.0 Example 5 6.0 Comparative Example 1 7.5 Comparative Example 2 7.5 Comparative Example 3 7.9

[0093] The data from Test Example 1 show that the lightweight PU foam sole prepared in Example 1 has the best shock absorption performance and excellent flexural resistance.

[0094] The di(3-trimethoxysilylpropyl)amine used in Example 1 exhibits superior shock-absorbing and folding-resistant properties compared to the tetra-sec-butoxysilane of Example 2, the tetramethoxysilane of Example 3, and the n-propyl tri-methoxy silicate of Comparative Example 1, primarily due to its unique molecular structure. The di(3-trimethoxysilylpropyl)amine molecule contains two trimethoxysilane groups, which provide abundant crosslinking sites and facilitate chemical bonding with other components, forming a more complex and stable crosslinking network. This network structure can effectively absorb and disperse impact energy, significantly improving shock-absorbing properties. At the same time, the high density and stability of its crosslinking network also enhance the folding resistance of the material, allowing the sole to maintain good structural integrity during repeated bending. In contrast, while tetra-sec-butoxysilane, tetramethoxysilane, and n-propyl tri-methoxy silicate can also form crosslinking structures, they lack such abundant crosslinking sites, resulting in insufficient complexity and stability of the crosslinking network, and thus exhibit slightly weaker shock-absorbing and folding-resistant properties.

[0095] The 1-(3-glycidyloxypropyl)-1,1,3,3,3-pentaethoxy-1,3-disilopropane used in Example 1 exhibits superior shock-absorbing and folding-resistant properties compared to the 3-glycidyloxypropylmethyldiethoxysilane of Example 4 and the 3-[(2,3)-epoxypropoxy]propylmethyldimethoxysilane of Comparative Example 2, primarily due to its unique molecular structure. The 1-(3-glycidyloxypropyl)-1,1,3,3,3-pentaethoxy-1,3-disilopropane molecule contains a glycidyl ether group and a pentaethoxysilane group, which not only provide abundant crosslinking sites but also facilitate chemical bonding with other components such as polyacrylamide through the high reactivity of the glycidyl ether group, forming a more complex and stable crosslinking network. This network structure can effectively absorb and disperse impact energy, significantly improving shock-absorbing properties. At the same time, the high density and stability of its crosslinking network also enhance the folding resistance of the material, allowing the sole to maintain good structural integrity during repeated bending. In contrast, while 3-glycidyloxypropylmethyldiethoxysilane and 3-[(2,3)-epoxypropoxy]propylmethyldimethoxysilane can also form crosslinking structures, their relatively fewer reactive groups (glycidyloxy and epoxypropoxy) result in insufficient complexity and stability of the crosslinking network, and thus exhibit slightly weaker shock-absorbing and folding-resistant properties.

[0096] The bis-[3-(triethoxysilyl)propyl]-tetrasulfide in Example 5 is more flexible due to the presence of a four-sulfur chain, and its crosslinking network is more elastic, providing better folding resistance. Its shock-absorbing properties are comparable to those of Example 1, as both have similar abilities to absorb impact energy. The di(3-trimethoxysilylpropyl)amine of Example 1 lacks a flexible structure and has slightly weaker folding resistance.

Claims

1. A method for preparing a light weight PU foamed sole, characterized in that, The method is as follows, in parts by weight: Step 1, 15~25 parts of ethylene-vinyl acetate copolymer, 10~20 parts of ethylene octene copolymer, 5~10 parts of SBS thermoplastic elastomer, 5~15 parts of polyether polyurethane are mixed into an internal mixer, and mixed for 8~12 minutes, 4~6 parts of kaolin, 0.5~1 parts of calcium stearate, 2~4 parts of paraffin oil are continuously added and mixed, and when the mixing temperature reaches 90~100℃, it is kept for 3~5 minutes, then it is turned over once, when the mixing temperature rises to 95~105℃, it is turned over twice, when the mixing temperature rises to 100~110℃, it is turned over three times, when the mixing temperature rises to 105~115℃, it is turned over four times, when the mixing temperature rises to 110~120℃, it is turned over five times, and then it is mixed for 2~4 minutes, and the glue is discharged, and it is placed at room temperature for 10~48 hours to obtain a mixture; Step 2, the mixture prepared in step 1 is added to a two-roll open mill, 0.5~2 parts of azodicarbonamide, 1~2 parts of shock-absorbing additive, 0.5~1 part of dimethyl silicone oil, and 0.5~1 part of di-t-butyl peroxide are added, and mixed, and the mixed material is made into a sheet; Step 3, the sheet prepared in step 2 is cut into a shoe sole shape, and foamed and formed in a shoe sole mold, and after foaming is completed, it is naturally cooled to room temperature to obtain a light PU foamed shoe sole; The preparation method of the shock-absorbing additive is as follows, in parts by weight: 15~25 parts of organosilicon compound and 5~10 parts of functional organosilane are mixed and added to 120~180 parts of water, and stirred at a temperature of 70~80℃ for 2~5 hours to obtain a pretreated material; 10~20 parts of polyacrylamide is dissolved in 200~400 parts of water, heated to 65~75℃ and stirred uniformly to prepare an active solution; then 5~10 parts of talc, 2~6 parts of bentonite, 4~8 parts of boron oxide and 4~6 parts of ammonium dihydrogen phosphate are added to 100~150 parts of water to form a suspension, and the active solution is added dropwise to the pretreated material at a dropwise speed of 10~30 mL / min, and stirred at a temperature of 70~90℃ for 1~3 hours, and then mixed uniformly with the suspension, and freeze-dried to obtain the shock-absorbing additive; The organosilicon compound is bis-[3-(triethoxysilyl)propyl]-tetrasulfide; The functional organosilane is 1-(3-glycidyl ether propyl)-1,1,3,3,3-pentaethoxy-1,3-disilane.

2. The method of claim 1, wherein, The temperature rising speed of the internal mixer in step 1 is 1~2℃ / min.

3. The method of claim 1, wherein, The mixing temperature in step 2 is 100~130℃, and the time is 5~15 minutes.

4. The method of claim 1, wherein, The thickness of the sheet in step 2 is controlled to be 2~4mm.

5. The method of claim 1, wherein, The foaming temperature in step 3 is 130~170℃.