An ultra-light high-rebound sole material and a preparation method thereof

Abstract

The application relates to the field of high polymer materials, and particularly discloses a super-light high-rebound sole material and a preparation method thereof.A super-light high-rebound sole material comprises the following raw materials in parts by weight: 50-60 parts of EVA resin, 5-12 parts of a polyamide elastomer, 15-25 parts of ozone-modified LDPE, 1-3 parts of maleic anhydride grafted EVA, 3-4 parts of an AC foaming agent, 0.9-1.2 parts of a crosslinking agent, 3.5-4 parts of a foaming promoter, 1-1.5 parts of stearic acid, 4-6 parts of a light wear-resistant agent and 15-20 parts of a filler.The sole material has the advantages of good rebound, low density, light weight, deformation resistance and wear resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, and more particularly to an ultra-light high-rebound sole material and a preparation method thereof. BACKGROUND

[0002] Children are a special group, especially children aged 0-3 years old, who are in the process of starting to walk steadily, and thus have higher requirements for shoes. A soft and anti-slip sole can adapt to the foot mechanics of children, improve the safety of children walking, and enable the feet to grow healthily. The hardness of the soles of current shoes is mostly the same. Even if there are shoes with different sole hardness, they are designed for the foot characteristics of adults. For manufacturers researching, designing and producing children's shoes, their attention is still limited to changes in the style, color and shape of children's shoes.

[0003] In the prior art, a Chinese patent application No. CN201710422711.1 discloses an anti-slip sole for children's shoes, which is made of the following components: natural rubber, styrene-butadiene rubber, filler, stearic acid, plasticizer, foaming agent, polyethylene resin, calcium sulfate whisker, modified nano magnesium oxide and activated attapulgite. The anti-slip sole for children's shoes has increased wet skid resistance and friction coefficient of the sole and improved anti-slip property through the synergistic effect of the modified magnesium oxide and the activated attapulgite. However, the sole is hard and heavy, has poor cushioning and shock absorption effect when walking, cannot provide favorable cushioning, is prone to cause foot fatigue, and is not conducive to the growth and development of children's feet. SUMMARY

[0004] In order to improve the rebound resilience and lightness of the sole material for children's shoes, the present application provides an ultra-light high-rebound sole material and a preparation method thereof.

[0005] In the first aspect, the present application provides an ultra-light high-rebound sole material, which adopts the following technical solution:

[0006] An ultra-light high-rebound sole material includes the following raw materials by weight: 50-60 parts of EVA resin, 5-12 parts of polyamide elastomer, 15-25 parts of ozone-modified LDPE, 1-3 parts of maleic anhydride grafted EVA, 3-4 parts of AC foaming agent, 0.9-1.2 parts of crosslinking agent, 3.5-4 parts of foaming promoter, 1-1.5 parts of stearic acid, 4-6 parts of light wear-resistant agent, and 15-20 parts of filler.

[0007] By adopting the technical scheme, the polyamide elastomer is an elastomer obtained by copolymerization of nylon hard segments and polyether (or polyester) soft segments, has excellent wear resistance, high and low temperature resistance, tensile property, antistatic property and resilience and other characteristics, the polyamide hard segments form physical crosslinking points in the EVA melt, enhance the viscoelasticity of the system, inhibit the excessive expansion or merging of bubbles in the foaming process, thereby improving the cell uniformity; the melt strength is improved, the foaming ratio is increased, the density is further reduced, the polyether soft segments have excellent elastic recovery capacity, cooperate with the VA segments of the EVA, can reduce the deformation hysteresis, and improve the resilience of the material; the ozone-modified LDPE introduces oxygen-containing polar groups on the LDPE macromolecular chain, further optimizes the compatibility of the LDPE and the EVA, improves the interfacial bonding force of the LDPE and the EVA and the polyamide elastomer, the LDEP is more uniformly dispersed, the phase interface is closely combined, the cell structure is more uniform, the cell diameter is reduced, the foaming ratio is higher, the density is lower, and the LDPE itself has a certain flexibility, the compatibility of the modified LDPE and the EVA is improved, the stress concentration caused by the phase separation is reduced, the hard segment support of the polyamide elastomer is matched, a soft-hard-soft synergistic elastic structure is formed, and the overall resilience is improved.

[0008] Optionally, the polyamide elastomer accounts for 15-20% of the EVA resin, and the mass ratio of the polyamide elastomer to the ozone-modified LDPE is 1:2-3.

[0009] By adopting the technical scheme, the appropriate amount of the polyamide elastomer is used to avoid excessive melt viscosity, the gas decomposed by the foaming agent is difficult to expand, the foaming ratio is reduced, and the mass ratio of the polyamide elastomer to the ozone-modified LDPE is controlled to avoid the decrease of the compatibility caused by excessive nonpolar segments, so that the appropriate amount of the polyamide elastomer and the appropriate addition ratio of the polyamide elastomer to the ozone-modified LDPE can effectively improve the foaming uniformity of the EVA shoe sole material, reduce the density, realize the ultralightness, and improve the resilience.

[0010] Optionally, the EVA resin comprises EVA resins with VA contents of 14-18% and 26-33% at a mass ratio of 1:2-2.5.

[0011] By adopting the above technical scheme, the EVA resin with low VC content has high crystallinity, the proportion of ethylene segments in the molecular chain reaches, and shows higher rigidity and wear resistance, and the melt strength is high, the hole wall is more stable during foaming, which is beneficial to realize lightweight, and the EVA resin material with high VA content is more flexible and has high elasticity, so the two kinds of EVA resins with different VA contents are blended in a proper proportion, the EVA resin with low VA content can provide a rigid skeleton to reduce the surface wear of the EVA resin with high VA content, the EVA resin with high VA content can improve the foaming capacity, improve the uniformity of the cells, and improve the uniformity, and the EVA resin with low VA content can stabilize the cell structure and prevent excessive deformation and balance the compression permanent deformation.

[0012] Optionally, the lightweight wear-resistant agent is a porous PBT fiber modified by polycaprolactone.

[0013] By adopting the above technical scheme, the EVA foaming material has low tear resistance and low mechanical strength, the PBT itself has excellent rigidity, fatigue resistance and wear resistance, and can be introduced into the shoe sole material to support the fiber skeleton and reduce the wear of the EVA surface, and the porous fiber structure can reduce the density of the shoe sole, and the pores can retain the blowing agent gas to assist the formation of the cells to achieve the effect of lightweight, in addition, the high modulus of the PBT porous fiber can limit the excessive deformation of the EVA shoe sole to improve the dynamic rebound and tear resistance; the porous PBT fiber is modified by PCL, the flexible segment contained in the PCL has certain compatibility with the non-polar ethylene segment of the EVA resin, can play a bridge role, and can improve the interface bonding between the porous PBT fiber and the EVA resin, and the melting point of PCL is low, and when the EVA resin is blended and hot-melted, the PCL is hot-melted at the melting temperature of the EVA resin, and an interface transition layer is formed on the surface of the porous PBT fiber, the adhesion between the porous fiber and the EVA is increased, the interface bonding is significantly improved, the interface peeling is reduced, and the wear resistance, toughness and processing performance of the shoe sole material are improved.

[0014] Optionally, the filler includes talcum powder and PDA modified aramid nanofiber aerogel loaded with silicon dioxide in a mass ratio of 3-4:1.

[0015] By adopting the above technical scheme, the talc powder has a sheet structure and a hydrophobic surface, the surface planes of the talc sheet structure are connected by a very weak van der Waals force, so a relatively small shear force can be used to delaminate it, which is also the reason why the talc powder has a slippery feeling and low abrasion, and it can also be easily dispersed, and the introduction of the talc powder into the polymer as a filler can improve the dimensional stability and wear resistance of the polymer material; the aramid nanofiber is used as a micro-nano building unit, and polydopamine is formed on the surface thereof by chemical bonding oxidation, the polydopamine adheres to the silica, and a grape-like structure is formed, thereby increasing the interfacial bonding, the aramid nanofiber itself has ultrahigh strength and modulus, the surface of the aramid fiber coated with PDA is rich in active groups such as hydroxyl and amino groups, can form hydrogen bonds or covalent bonds with the amino and hydroxyl groups of chitosan, and can also enhance the compatibility with the EVA resin, reduce stress concentration, avoid uneven dispersion, improve the interfacial bonding force of the EVA matrix, and the silica as a hard particle can further strengthen the composite material and reduce the deformation and abrasion of the EVA after foaming; and the porous structure of the aerogel can disperse external force, and the rigidity of the silica can provide support, which helps to improve the compression resistance and resilience of the sole and reduce the fatigue after a long walk, and the low density of the aerogel can reduce the overall density of the sole material, avoid the sole being too heavy, and the porous structure can provide a time-limited buffer when air is compressed, thereby improving the walking comfort.

[0016] Optionally, the raw materials of the PDA modified aramid nanofiber aerogel loaded with silica include PDA modified aramid fiber, nanosilica, chitosan and glutaraldehyde in a mass ratio of 1:0.1-0.2:1-2:0.06-0.12.

[0017] By adopting the above technical scheme, the amino groups of chitosan and the aldehyde groups of glutaraldehyde are chemically crosslinked to form a dynamic crosslinking network, the aramid nanofiber is entangled to form a three-dimensional network due to hydrogen bonding force, and the two networks are dynamically locked, the crosslinking of chitosan and glutaraldehyde uniformly locks the aramid nanofiber in the network, and the glutaraldehyde crosslinked composite aerogel is prepared after freeze-drying, the double network interlocking structure effectively prevents the sliding of the aramid nanofiber, improves the structural stability of the aerogel, and makes the compression cycle of the aerogel good and the durability excellent, thereby improving the compression deformation ability of the sole material.

[0018] Optionally, the preparation method of the filler-loaded PDA modified aramid nanofiber aerogel is as follows:

[0019] The PDA modified aramid nanofiber is dispersed in anhydrous ethanol, nanosilica is added, and the mixture is uniformly mixed to prepare a blending liquid; chitosan powder is dissolved in 1M glacial acetic acid to prepare a chitosan solution;

[0020] The chitosan solution and the blend were mixed evenly, the pH was adjusted to 5.6-6, glutaraldehyde was added, and after mixing evenly, the mixture was frozen in liquid nitrogen, freeze-dried under vacuum, and annealed to obtain aramid fiber aerogel loaded with silica.

[0021] By adopting the above technical solution, aramid nanofibers are used as a rigid skeleton, combined with a flexible cross-linked network formed by chitosan-glutaraldehyde, to form a dual-network structure that combines rigidity and flexibility. This structure can resist external deformation through aramid nanofibers and silica, and absorb energy through the deformation of the chitosan network, reducing foam brittleness and improving the impact resistance, abrasion resistance, and tear resistance of the sole. In addition, the porosity of the dual-network structure can serve as nucleation points for cells during the foaming process, promoting uniform cell distribution. At the same time, the silica nanoparticles can stabilize the cell walls, reduce cell merging or rupture, increase the closed-cell rate, and enhance the cushioning performance and lightweight characteristics of the sole. Furthermore, the elastic recovery ability of the chitosan-glutaraldehyde network combined with the rigid support of aramid nanofibers reduces permanent deformation after EVA foaming and improves the compression resilience of the sole material.

[0022] Optionally, the ozone-modified LDPE is prepared by treating LDPE with ozone at a concentration of 55-60 mg / L at 80-85°C for 20-30 min.

[0023] By adopting the above technical solution, ozone is used to introduce oxygen-containing functional groups into the long-branched LDPE, thereby improving the compatibility between LDPE and EVA resin, improving the interfacial bonding tightness, and increasing the uniformity of the cell structure.

[0024] Optionally, the foaming accelerator comprises zinc stearate and zinc oxide in a mass ratio of 1.5:2-2.5.

[0025] By adopting the above technical solution, zinc oxide, an alkaline oxide, catalyzes the decomposition of AC foaming agent during the foaming process, effectively reducing the decomposition temperature of AC foaming agent and adjusting the crosslinking speed, thereby obtaining a foamed material with uniform and fine foaming. Zinc stearate is beneficial for demolding and can also promote the decomposition of AC foaming agent.

[0026] Optionally, the crosslinking agent is selected from at least one of dicumyl peroxide, 1,4-di-tert-butyl peroxide, and triallyl isocyanate.

[0027] By adopting the above technical solution, the addition of crosslinking agent in the system causes the independent polymer molecular chains such as EVA to crosslink into a three-dimensional network structure, so that the polymer has sufficient ability to constrain and encapsulate the gas generated by the decomposition of the foaming agent inside the polymer to form independent vesicles, thereby obtaining a shoe sole material with uniform and consistent cell size.

[0028] Secondly, this application provides a method for preparing an ultralight, high-resilience shoe sole material, employing the following technical solution:

[0029] A method for preparing an ultralight, high-resilience shoe sole material includes the following steps:

[0030] EVA resin, polyamide elastomer, ozone-modified LDPE, maleic anhydride-grafted EVA, AC foaming agent, crosslinking agent, foaming accelerator, stearic acid, lightweight abrasion-resistant agent, and filler are mixed evenly and kneaded at 120-140℃ for 10-15 minutes. Then, the mixture is molded and foamed at 140-165℃ and 10MPa for 20-25 minutes. Next, it is irradiated at 65-70kGy for 3-5 minutes and vertically foamed at 230-240℃ for 2-4 minutes to obtain the shoe sole material.

[0031] By adopting the above technical solution, the components are mixed and kneaded, then molded and foamed, and then irradiated and crosslinked to form a three-dimensional network structure, which significantly improves mechanical properties such as tear strength and tensile strength.

[0032] In summary, this application has the following beneficial effects:

[0033] 1. Because this application uses EVA resin, polyamide elastomer, ozone-modified LDPE, maleic anhydride-grafted EVA, lightweight abrasion-resistant agent, filler and other components to prepare shoe sole materials, it improves melt strength, increases foaming ratio, reduces density and improves resilience, and enhances elastic recovery ability, so that the finished shoe sole materials have the advantages of lightweight and high resilience, making them more suitable for the development of children's footwear.

[0034] 2. In this application, polycaprolactone-modified porous PBT fiber is preferably used as a lightweight abrasion-resistant agent. The porous structure of PBT fiber can reduce the density of the shoe sole material, increase the lightweight advantage, and also play a role in supporting the fiber skeleton, reducing wear, and increasing the resistance to deformation and tearing. Moreover, polycaprolactone has a low melting point and produces heat melting when it is blended and mixed with EVA, forming an interfacial adhesive layer on the surface of the porous PBT fiber, improving the interfacial bonding strength, and enhancing the tear resistance and abrasion resistance of the shoe sole material.

[0035] 3. In this application, talc powder and PDA-modified aramid nanofiber aerogel loaded with silica are preferred as fillers. The use of aerogel not only effectively reduces the material density and lightens the weight of the shoe sole, but also effectively improves the wear resistance and compression resistance of the shoe sole material and enhances its compression deformation capacity. Detailed Implementation

[0036] The following embodiments provide a further detailed description of this application.

[0037] Preparation Examples 1-5 of PDA-Modified Aramid Nanofiber Aerogels Loaded with Silica

[0038] In the preparation example, the aramid fiber was selected from Hephaestus, catalog number KH / DX-001, with a length of 3 mm and a thickness of 1.5D, and the chitosan was selected from Shanghai Zhenzhun Biotechnology, catalog number CS-3001.

[0039] Preparation Example 1: Aramid fibers were cut into small pieces and dispersed in a 15 wt% sodium hydroxide solution at a bath ratio of 1:250. The solution was treated at 80°C for 30 min, filtered, washed until neutral, and dried to obtain aramid nanofibers. 10 g of aramid nanofibers were dispersed in water to form a 0.5 wt% dispersion. 10 g of PDA powder was added, and the pH was adjusted to 8.5 with Tris alkaline buffer. The mixture was stirred and polymerized at room temperature for 24 h. The solution was washed twice with anhydrous ethanol to obtain PDA-modified aramid nanofibers.

[0040] 10g of PDA-modified aramid nanofibers were dispersed in 400g of anhydrous ethanol, 2g of nano-silica was added, and the mixture was ultrasonically dispersed for 20min to obtain a blend. 20g of chitosan powder was added to 1M glacial acetic acid and stirred at 80℃ for 30min to dissolve, thus obtaining a chitosan solution with a concentration of 3wt%.

[0041] The blend and chitosan solution were mixed evenly, the pH was adjusted to 5.6 with 1M sodium hydroxide solution, 1.2g glutaraldehyde was added, and the mixture was stirred for 12h. The mixture was then frozen in a liquid nitrogen bath for 20min and freeze-dried at -50℃ and 1Pa vacuum for 48h. Finally, it was annealed in a vacuum oven at 110℃ for 1h to obtain PDA-modified aramid nanofiber aerogel loaded with silica.

[0042] Preparation Example 2: Aramid fibers were cut into small pieces and dispersed in a 15 wt% sodium hydroxide solution at a bath ratio of 1:250. The solution was treated at 80°C for 30 min, filtered, washed until neutral, and dried to obtain aramid nanofibers. 10 g of aramid nanofibers were dispersed in water to form a 0.3 wt% dispersion. 10 g of PDA powder was added, and the pH was adjusted to 8.5 with Tris alkaline buffer. The mixture was stirred and polymerized at room temperature for 24 h. The solution was washed twice with anhydrous ethanol to obtain PDA-modified aramid nanofibers.

[0043] 10g of PDA-modified aramid nanofibers were dispersed in 400g of anhydrous ethanol, 1g of nano-silica was added, and the mixture was ultrasonically dispersed for 30min to obtain a blend. 10g of chitosan powder was added to 1M glacial acetic acid and stirred at 90℃ for 20min to dissolve, thus obtaining a chitosan solution with a concentration of 5wt%.

[0044] The blend and chitosan solution were mixed evenly, the pH was adjusted to 6 with 1M sodium hydroxide solution, 0.6g glutaraldehyde was added, and the mixture was stirred for 12h. The mixture was then frozen in a liquid nitrogen bath for 30min and freeze-dried at -50℃ and 1Pa vacuum for 48h. Finally, it was annealed in a vacuum oven at 110℃ for 1h to obtain PDA-modified aramid nanofiber aerogel loaded with silica.

[0045] Preparation Example 3: The difference from Preparation Example 1 is that chitosan solution and glutaraldehyde were not added. The preparation method is as follows:

[0046] Aramid fibers were cut into small pieces and dispersed in a 15 wt% sodium hydroxide solution at a bath ratio of 1:250. The solution was treated at 80°C for 30 min, filtered, washed until neutral, and dried to obtain aramid nanofibers. 10 g of aramid nanofibers were dispersed in water to form a 0.5 wt% dispersion. 10 g of PDA powder was added, and the pH was adjusted to 8.5 with Tris alkaline buffer. The mixture was stirred and polymerized at room temperature for 24 h. The solution was washed twice with anhydrous ethanol to obtain PDA-modified aramid nanofibers.

[0047] 10g of PDA-modified aramid nanofibers were dispersed in 400g of anhydrous ethanol, and 2g of nano-silica was added. The mixture was ultrasonically dispersed for 20min to obtain a blend.

[0048] The blend was frozen in a liquid nitrogen bath for 20 min, freeze-dried at -50 °C and 1 Pa vacuum for 48 h, and then annealed in a vacuum oven at 110 °C for 1 h to obtain PDA-modified aramid nanofiber aerogel loaded with silica.

[0049] Preparation Example 4: The difference from Preparation Example 1 is that silica was not loaded. 10g of PDA-modified aramid nanofibers were dispersed in 400g of anhydrous ethanol and ultrasonically dispersed for 20min to obtain a blend. The rest of the method was the same as in Preparation Example 1 to obtain PDA-modified aramid nanofiber aerogel.

[0050] Preparation Example 5: The difference from Preparation Example 1 is that no silica was added, no PDA was used for modification, and no chitosan solution was added. The specific preparation method is as follows: Aramid fibers were cut into small pieces and dispersed in a 15wt% sodium hydroxide solution at a bath ratio of 1:250. The solution was treated at 80℃ for 30 min, filtered, washed until neutral, and dried to obtain aramid nanofibers. 10g of aramid nanofibers were dispersed in 400g of anhydrous ethanol and ultrasonically dispersed for 20 min to obtain a blend. The blend was frozen in a liquid nitrogen bath for 20 min and freeze-dried at -50℃ and 1Pa vacuum for 48 h. Then it was annealed in a vacuum oven at 110℃ for 1 h to obtain aramid nanofiber aerogel.

[0051] Preparation of porous PBT fibers Example 6

[0052] Preparation Example 6: PBT was dried at 100℃ for 10h, mixed with PP at a mass ratio of 70:30, and the raw fibers were obtained at 225℃ with a spinneret diameter of 1mm. The fibers were then stretched 4 times at 40℃, placed in xylene solution at 120℃ for 40min at a bath ratio of 1:30, washed with ethanol, and dried to obtain porous PBT fibers. The PBT was selected from Chang Chun, Taiwan, China, with a model number of 1100, and the PP was selected from Sinopec, with a model number of T30S.

[0053] Example

[0054] Example 1: An ultralight, high-resilience shoe sole material, the raw material quantities of which are shown in Table 1, wherein the EVA resin comprises EVA resin with a VA content of 14% and EVA resin with a VA content of 26% in a mass ratio of 1:2. The EVA resin with a VA content of 14% is selected from Beijing Dongfang Petroleum, model Y2022, and the EVA resin with a VA content of 26% is selected from Formosa Plastics (Taiwan), model 7470M. The polyamide elastomer is selected from Pebax, model Arkema MF5070. The ozone-modified LDPE is prepared by a gas flow rate of 0.11m³. 3 Ozone at a concentration of 55 mg / L was used to treat LDPE at 80°C for 30 min. The LDPE was selected from Yanshan Petrochemical, model 1I2A-1. Maleic anhydride-grafted EVA was selected from ExxonMobil, model VA1803. The crosslinking agent was DCP. The foaming accelerator was a mixture of zinc stearate and zinc oxide in a mass ratio of 1.5:2.5. The lightweight wear-resistant agent was alumina, and the filler was talc.

[0055] The preparation method of the above-mentioned ultralight high-resilience shoe sole material includes the following steps:

[0056] EVA resin, polyamide elastomer, ozone-modified LDPE, maleic anhydride-grafted EVA, AC foaming agent, crosslinking agent, foaming accelerator, stearic acid, lightweight abrasion-resistant agent, and filler are mixed evenly and kneaded at 140℃ for 10 min. Then, the mixture is molded and foamed at 165℃ and 10MPa for 20 min, followed by irradiation at 70kGy for 3 min and vertical foaming at 240℃ for 2 min to obtain the shoe sole material.

[0057] Table 1. Raw material consumption of ultralight high-resilience shoe sole materials in Examples 1-5

[0058]

[0059] Example 2: An ultralight, high-resilience shoe sole material, the raw material quantities of which are shown in Table 1, wherein the EVA resin comprises EVA resin with a VA content of 18% and EVA resin with a VA content of 33% in a mass ratio of 1:2.5. The EVA resin with a VA content of 18% is selected from DuPont, USA, product number 3165, and the EVA resin with a VA content of 33% is selected from Exxon, model number UL02133. The polyamide elastomer is selected from Pebax, model number Arkema MF5070. The ozone-modified LDPE is prepared by a gas flow rate of 0.11m³. 3 Ozone at a concentration of 60 mg / L was used to treat LDPE at 85°C for 20 min. The LDPE was selected from Yanshan Petrochemical, model 1I2A-1. Maleic anhydride-grafted EVA was selected from ExxonMobil, model VA1803. The crosslinking agent was DCP. The foaming accelerator was a mixture of zinc stearate and zinc oxide in a mass ratio of 1.5:2. The lightweight wear-resistant agent was alumina, and the filler was talc.

[0060] The preparation method of the above-mentioned ultralight high-resilience shoe sole material includes the following steps:

[0061] EVA resin, polyamide elastomer, ozone-modified LDPE, maleic anhydride-grafted EVA, AC foaming agent, crosslinking agent, foaming accelerator, stearic acid, lightweight abrasion-resistant agent, and filler are mixed evenly and kneaded at 120°C for 15 min. Then, the mixture is molded and foamed at 140°C and 10 MPa for 25 min, followed by irradiation at 60 kGy for 5 min and vertical foaming at 230°C for 4 min to obtain the shoe sole material.

[0062] Examples 3-5: An ultralight high-resilience shoe sole material, which differs from Example 1 in that the raw material usage is as shown in Table 1.

[0063] Example 6: An ultralight high-resilience shoe sole material, which differs from Example 1 in that the EVA resin is EVA resin with a VA content of 14%.

[0064] Example 7: An ultralight high-resilience shoe sole material, which differs from Example 1 in that the EVA resin is EVA resin with a VA content of 33%.

[0065] Example 8: An ultralight high-resilience shoe sole material, which differs from Example 1 in that the lightweight abrasion-resistant agent is polycaprolactone-modified porous PBT fiber. The specific preparation method is as follows: the porous PBT fiber prepared in Example 6 is immersed in an acetone solution with a concentration of 10 wt% polycaprolactone, and after 30 minutes it is taken out and dried. The polycaprolactone is selected from Perstorp in Sweden, with the product number pcl6500.

[0066] Example 9: An ultralight high-resilience shoe sole material, which differs from Example 8 in that the lightweight abrasion-resistant agent is the porous PBT fiber prepared in Preparation Example 6, without impregnation treatment with polycaprolactone in acetone solution.

[0067] Example 10: An ultralight high-resilience shoe sole material, which differs from Example 8 in that the filler includes talc powder in a mass ratio of 3:1 and PDA-modified aramid nanofiber aerogel loaded with silica, and the PDA-modified aramid nanofiber aerogel loaded with silica is prepared by Preparation Example 1.

[0068] Example 11: An ultralight high-resilience shoe sole material, which differs from Example 8 in that the filler includes talc powder in a mass ratio of 4:1 and PDA-modified aramid nanofiber aerogel loaded with silica, and the PDA-modified aramid nanofiber aerogel loaded with silica is prepared by Preparation Example 2.

[0069] Example 12: An ultralight high-resilience shoe sole material, which differs from Example 10 in that the PDA-modified aramid nanofiber aerogel loaded with silica is prepared by Example 3.

[0070] Example 13: An ultralight high-resilience shoe sole material, which differs from Example 10 in that the PDA-modified aramid nanofiber aerogel loaded with silica is prepared by Example 4.

[0071] Example 14: An ultralight high-resilience shoe sole material, which differs from Example 10 in that the PDA-modified aramid nanofiber aerogel loaded with silica is prepared by Example 5.

[0072] Comparative Example

[0073] Comparative Example 1: An ultralight high-resilience shoe sole material, which differs from Example 1 in that an equal amount of polyamide elastomer is used instead of ozone-modified LDPE.

[0074] Comparative Example 2: An ultralight high-resilience shoe sole material, which differs from Example 1 in that an equal amount of ozone LDPE is used instead of polyamide elastomer.

[0075] Comparative Example 3: An ultralight high-resilience shoe sole material, which differs from Example 1 in that an equal amount of EVA resin (containing EVA resin with a VA content of 14% and EVA resin with a VA content of 26% in a mass ratio of 1:2) is used to replace ozone-modified LDPE and polyamide elastomer.

[0076] Performance testing

[0077] Ultralight high-resilience shoe sole materials were prepared according to the methods in the examples and comparative examples, and their performance was tested according to the following methods. The test results are recorded in Table 2.

[0078] 1. Density: Tested in accordance with GB / T6343-2009 "Determination of Apparent Density of Foamed Plastics and Rubber".

[0079] 2. DIN Abrasion: The test was conducted in accordance with GB / T9867-2008 "Determination of Abrasion Resistance of Vulcanized Rubber or Thermoplastic Rubber (Rotary Roller Abrasion Tester Method)". The roller diameter was 150±2mm, the roller length was 460mm, the roller speed was 40±1r / min, the sample specifications were 16±0.2mm in length and 6mm in thickness, the transverse speed of the sample holder was 4.2±0.06mm / r, the grinding stroke length was 20m, the grinding speed was 0.9r / min, the self-load was 2.5N, the sample load was 10N, and 3 samples were taken for each group. The test results were averaged.

[0080] 3. Rebound Rate: The test is conducted according to GB / T10652-2001 "Determination of Elasticity of Porous Polymer Elastic Materials". A steel ball is dropped from a specified height onto the test piece, and its rebound height is measured. The ball rebound tester includes a vertical transparent test tube with an inner diameter of 40±10mm. The test tube contains a steel ball weighing 16±0.5g with a diameter of 16±0.5mm, released via a magnet and other devices. The steel ball should fall without rotation and effectively align with the center. The drop height should be 500±0.5mm. To facilitate recording the peak position of the rebound, the peak should be 516mm above the test plate surface. The rebound "zero point" should be the diameter of the ball above the test surface. Five samples are taken per group, and the average value is used.

[0081] 4. Compression set: The test shall be conducted in accordance with HG / T2876-2009 "Test Method for Compression Deformation of Microporous Materials for Rubber and Plastic Shoes". The sole material shall be made into a standard specimen and compressed on a compression fixture for a certain period of time. The compression set shall be measured and the compression set shall be calculated according to the following formula: K=(H0-H) / H×100%, where K is the compression set (%), H0 is the height before the test (mm), and H is the height after the test and after the test (mm). Five specimens shall be taken in each group and the average value of the test results shall be taken.

[0082] 5. Tear Strength: The test shall be conducted in accordance with GB / T529-1999 "Determination of Tear Strength of Vulcanized Rubber or Thermoplastic Rubber (Pants-shaped, Right-angled and Crescent-shaped Specimens)". Pants-shaped specimens shall be used. The load value of the tensile testing machine shall be set to zero. The specimen shall be clamped in the fixture of the tensile testing machine. The specimen shall be carefully adjusted to make it symmetrical in all directions. The elongation reading of the tensile elongation measurement system shall be zeroed. Then, the tensile testing machine shall be started at a tensile speed of 100±10 mm / min. The maximum load during the tensile process shall be recorded (accurate to ±1%). The tear strength shall be calculated according to the following formula: T=F / d, where T is the tear strength, N / mm, F is the average force, N, and d is the specimen width, mm. Five specimens shall be tested in each group.

[0083] Table 2 Performance test results of ultralight high-resilience shoe sole materials

[0084]

[0085] Based on the data in Table 2 and the raw material selection and dosage in Examples 1-5, it can be seen that the density of the shoe sole material prepared in Examples 1-5 is less than 1 g / cm³. 3 The DIN material exhibits low wear, high resilience, low compression deformation, high tear strength, and strong tear resistance, indicating that the raw materials and methods described in this application can produce ultra-lightweight EVA soles with ultra-low density, high dimensional stability, and high tear resistance, making them particularly suitable for producing children's EVA toddler shoes.

[0086] In Example 6, EVA resin with a VA content of 14% was used alone, while in Example 7, EVA resin with a VA content of 33% was used alone. Compared with Example 1, the sole material in Example 6 has stronger rigidity, less DIN wear, lower rebound rate, and greater compression deformation, while the sole material in Example 7 has a higher rebound rate, but greater wear and worse abrasion resistance.

[0087] Compared with Example 1, Example 8 uses polycaprolactone-modified porous PBT fiber as a lightweight abrasion agent. As shown in Table 2, compared with alumina as a lightweight abrasion agent in Example 1, the sole material made in Example 8 has stronger tear resistance and abrasion resistance, and also has a lower compression deformation rate and better resilience. This indicates that polycaprolactone-modified porous PBT fiber as a lightweight abrasion agent can effectively improve the lightweight effect of sole materials and enhance abrasion resistance, tear resistance and compression deformation resistance.

[0088] In Example 9, only porous PBT fibers were used without polycaprolactone impregnation. Compared with Example 8, the tear strength was reduced, the density did not change significantly, and the DIN wear was slightly increased.

[0089] Compared with Example 8, Examples 10 and 11 used talc powder and PDA-modified aramid nanofiber aerogel loaded with silica as fillers. Moreover, the PDA-modified aramid nanofiber aerogel loaded with silica was prepared by Preparation Example 1 and Preparation Example 2, respectively. It can be seen that the shoe sole materials prepared in Examples 10 and 11 have a lower density, a lower compression set, and a higher resilience.

[0090] In Example 12, the PDA-modified aramid fiber aerogel loaded with silica prepared in Preparation Example 3 was used. Compared with Example 10, no chitosan solution and glutaraldehyde were added, and no double network structure was formed. It can be seen that the shoe sole material prepared in Example 12 has a lower compression set and reduced abrasion resistance.

[0091] In Example 13, the PDA-modified aramid fiber aerogel loaded with silica was prepared from Preparation Example 4. Compared with Example 10, it was not loaded with silica, and a double network structure was formed by PDA-modified aramid fiber, glutaraldehyde, and chitosan. Its wear resistance decreased, its tear resistance weakened, and its compression set increased slightly.

[0092] In Example 14, the PDA-modified aramid fiber aerogel loaded with silica prepared in Preparation Example 5 was used. Compared with Example 10, no silica was added, no PDA modification was used, and no chitosan solution was added. Only the aramid nanofibers were made into aerogel. The shoe sole material prepared in Example 14 showed a decrease in density, DIN abrasion, compression set, and tear resistance.

[0093] Comparative Example 1 used only polyamide elastomer, Comparative Example 2 used ozone-modified LDPE, and Comparative Example 3 did not add ozone-modified LDPE or polyamide elastomer. Compared with Example 1, the sole materials prepared by Comparative Example 1 and Comparative Example 2 had increased density and mass, and their abrasion resistance, rebound effect and mechanical properties were worse. Moreover, the cushioning, rebound and abrasion resistance of the sole material prepared by Comparative Example 3 were significantly reduced.

[0094] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A lightweight, high-resilience shoe sole material, characterized in that, The raw materials include the following parts by weight: 50-60 parts EVA resin, 5-12 parts polyamide elastomer, 15-25 parts ozone-modified LDPE, 1-3 parts maleic anhydride-grafted EVA, 3-4 parts AC foaming agent, 0.9-1.2 parts crosslinking agent, 3.5-4 parts foaming accelerator, 1-1.5 parts stearic acid, 4-6 parts lightweight abrasion-resistant agent, and 15-20 parts filler; The EVA resin comprises EVA resin with a VA content of 14-18% and EVA resin with a VA content of 26-33% in a mass ratio of 1:2-2.5; The lightweight abrasion-resistant agent is polycaprolactone-modified porous PBT fiber. The filler comprises talc powder in a mass ratio of 3-4:1 and PDA-modified aramid nanofiber aerogel loaded with silica. The polycaprolactone-modified porous PBT fiber is made by impregnating porous PBT fiber with an acetone solution of polycaprolactone. The method for preparing the porous PBT fiber is as follows: PBT is dried at 100°C for 10 hours, mixed with PP at a mass ratio of 70:30, and the initial fiber is obtained at 225°C with a spinneret diameter of 1 mm. The initial fiber is then stretched 4 times at 40°C, placed in a xylene solution at 120°C for 40 minutes at a bath ratio of 1:30, washed with ethanol, and dried to obtain the porous PBT fiber. The PDA-modified aramid nanofiber aerogel loaded with silica was prepared by the following method: Aramid fibers were cut into small pieces and dispersed in sodium hydroxide solution at a bath ratio of 1:

250. The solution was treated at 80°C for 30 min, filtered, washed until neutral, and dried to obtain aramid nanofibers. The aramid nanofibers were dispersed in water to form a dispersion, PDA powder was added, and the pH was adjusted to 8.5 with Tris alkaline buffer. The mixture was stirred and polymerized at room temperature and washed with anhydrous ethanol to obtain PDA-modified aramid nanofibers. PDA-modified aramid nanofibers were dispersed in anhydrous ethanol, nano-silica was added, and ultrasonic dispersion was performed to obtain a blend. Chitosan powder was added to 1M glacial acetic acid and stirred to dissolve to obtain a chitosan solution. The blend and chitosan solution were mixed evenly, the pH was adjusted to 5.6 with 1M sodium hydroxide solution, glutaraldehyde was added, the mixture was stirred, frozen in a liquid nitrogen bath, freeze-dried under vacuum, and then annealed at 110℃ for 1 h to obtain PDA-modified aramid nanofiber aerogel loaded with silica.

2. The ultralight high-resilience shoe sole material according to claim 1, characterized in that: The amount of polyamide elastomer used is 15-20% of EVA resin, and the mass ratio of polyamide elastomer to ozone-modified LDPE is 1:2-3.

3. The ultralight high-resilience shoe sole material according to claim 1, characterized in that: The raw materials for the silica-loaded PDA-modified aramid nanofiber aerogel include PDA-modified aramid fibers, nano-silica, chitosan, and glutaraldehyde in a mass ratio of 1:0.1-0.2:1-2:0.06-0.

12.

4. The ultralight high-resilience shoe sole material according to claim 1, characterized in that: The ozone-modified LDPE is prepared by treating LDPE with ozone at a concentration of 55-60 mg / L at 80-85°C for 20-30 minutes.

5. The ultralight high-resilience shoe sole material according to claim 1, characterized in that: The foaming accelerator comprises zinc stearate and zinc oxide in a mass ratio of 1.5:2-2.

5.

6. The ultralight high-resilience shoe sole material according to claim 1, characterized in that: The crosslinking agent is selected from at least one of dicumyl peroxide, 1,4-di-tert-butyl peroxide, and triallyl isocyanate.

7. A method for preparing an ultralight high-resilience shoe sole material, which is applied to the ultralight high-resilience shoe sole material according to any one of claims 1-6, characterized in that: Includes the following steps: EVA resin, polyamide elastomer, ozone-modified LDPE, maleic anhydride-grafted EVA, AC foaming agent, crosslinking agent, foaming accelerator, stearic acid, lightweight abrasion-resistant agent, and filler are mixed evenly and kneaded at 120-140℃ for 10-15 minutes. Then, the mixture is molded and foamed at 140-165℃ and 10MPa for 20-25 minutes. Next, it is irradiated at 65-70kGy for 3-5 minutes and vertically foamed at 230-240℃ for 2-4 minutes to obtain the shoe sole material.

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