A foamed shoe sole material with a low damping g value and a method for producing the same

Abstract

The application provides a foamed shoe sole material with low damping G value and a preparation method thereof, the foamed shoe sole material is prepared from EVA material through foaming; the EVA material comprises the following components: 40-55 parts of EVA, 5-15 parts of acrylic acid-2-ethylhexyl ester / cumene acid monoester copolymer rubber, 10-20 parts of directional hydrogenated SEBS, 5-10 parts of POE, 5-10 parts of EPDM, 5-10 parts of OBC, 4-8 parts of reinforcing filler, 3-5 parts of microcapsule expanding agent, 0.5-0.8 parts of crosslinking agent, 2-3 parts of AC foaming agent, 1-1.5 parts of zinc oxide, 0.5-1.2 parts of stearic acid and 0.5-1.3 parts of stearate. The foamed shoe sole material has special circular closed cells in the interior, the circular cells produce large deformation in the movement process, so that the impact force is greatly reduced, and the foamed shoe sole material has higher rebound, and the extreme experience of consumers in the movement process is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of shoe materials, and particularly relates to a foamed shoe sole material with a low shock attenuation G value and a preparation method thereof. BACKGROUND

[0002] The shock absorption system is the most important part of sports shoes. When exercising, the human body will constantly bear a large gravity. When the foot lands, a considerable impact force will also be generated. However, the impact force that has a greater impact on the human body is the rebound force from the ground after the foot lands. A pair of shoes with shock absorption function can prevent sports injuries, especially prevent shin pain, fractures and joint pain; reduce fatigue, quickly recover physical strength, and not easily cause foot soreness, that is, relatively improve the sports performance. With the diversification of shoe products, the increasing update of shoe materials, and the continuous progress of shoemaking technology, more and more performance indicators of shoes are required. During the movement, with the different movement speeds, the foot will usually be subjected to a rebound impact force of 1.3-3 times the gravity, the faster the movement speed, the greater the weight of the runner, the greater the loading rate of the force, and the greater the rebound impact force. Therefore, it is imperative to develop a foamed shoe sole material with a low shock attenuation G value (the lower the G value, the better the shock attenuation performance).

[0003] In the prior art, the shock attenuation performance is improved to a certain extent by structure or formula design. For example, Chinese patent document 201910697047.0 mentions a kind of shock absorption shoe sole, and the internal shock absorption structure includes a plurality of stacked bubble sheets and hot melt adhesive films therebetween. The technology is a structure design improved shock absorption shoe sole, but the shock attenuation G value of the shoe sole before fatigue is 10.7, and the shock attenuation G value after fatigue is 11.8, and the shock attenuation level still needs to be improved. For example, Chinese patent document 201910832129.1 mentions a kind of high shock attenuation large pore foamed insole material, which is prepared from an EVA composite material; the EVA composite material includes the following components by mass fraction: 40-70 parts of ethylene-vinyl acetate copolymer; 10-30 parts of alpha-olefin thermoplastic elastomer; 10-30 parts of styrene copolymer; 0.4-0.6 parts of crosslinking agent; 2-4 parts of dinitrosopentamethylenetetramine; 2-4 parts of urea fat. The foamed insole material is a 2-5mm large pore design shock absorption shoe sole, and the shock attenuation G value is greater than or equal to 9.5. It can be seen that in the existing EVA series shock attenuation shoe sole foaming material, there is no technology with a shock attenuation G value lower than 9.5, or even lower. SUMMARY

[0004] Therefore, the present application provides a foamed shoe sole material with a low shock attenuation G value and a preparation method thereof. The foamed shoe sole material provided by the present application has a lower shock attenuation G value, which is beneficial to reducing the impact force in shoe applications, and has a higher rebound, thereby improving the experience of consumers during the movement.

[0005] The present application provides a foamed shoe sole material with low damping G value, which is prepared from EVA material by foaming; the EVA material comprises, in parts by weight, EVA 40-55 parts, acrylic acid-2-ethylhexyl ester / cinnamic acid monoester copolymer rubber 5-15 parts, oriented hydrogenated SEBS 10-20 parts, POE 5-10 parts, EPDM 5-10 parts, OBC 5-10 parts, reinforcing filler 4-8 parts, microcapsule expanding agent 3-5 parts, crosslinking agent 0.5-0.8 parts, AC foaming agent 2-3 parts, zinc oxide 1-1.5 parts, stearic acid 0.5-1.2 parts, and stearate 0.5-1.3 parts; the reinforcing filler is activated sepiolite fiber powder.

[0006] Preferably, the content of styrene unit structure of the oriented hydrogenated SEBS is 35-40%, and the hydrogenation degree is 50-80%.

[0007] Preferably, the reinforcing filler is acid, acid anhydride or coupling agent treated activated sepiolite fiber powder.

[0008] Preferably, the reinforcing filler is titanium acid ester coupling agent activated sepiolite fiber powder, and the activation degree is >80%.

[0009] Preferably, the initial decomposition temperature of the microcapsule expanding agent is 118-128℃, and the maximum decomposition temperature is 172-187℃.

[0010] Preferably, the content of vinyl acetate unit structure of the EVA is 18-30%.

[0011] Preferably, the crystallinity of the POE, EPDM and OBC is less than 18% respectively.

[0012] The crosslinking agent is dicumyl peroxide and / or 1,4-bis-tert-butyl peroxyl isopropyl benzene; and the stearate is zinc stearate.

[0013] Preferably, the damping G value of the foamed shoe sole material is not greater than 8, and the resilience rate is above 60%.

[0014] The present application provides a preparation method of the foamed shoe sole material as described above, comprising the following steps:

[0015] The EVA material is sequentially mixed and granulated, and then at least foamed and formed once to obtain the foamed shoe sole material with low damping G value for sports shoes.

[0016] Preferably, the mixing temperature is 80-110℃, and the granulation temperature is 80-95℃.

[0017] The test method of shock absorption G value known in the art includes: rapidly applying pressure by a falling object, continuously measuring the entire loading and unloading compression cycle by a pressure and displacement sensor, and calculating the change in displacement by pressure recording. The impact speed of the object depends on the falling height, the maximum pressure and displacement depend on the shock absorption performance of the shoe, and the maximum energy applied depends on the falling height and the shock absorption performance of the shoe. The test standard of shock absorption G value includes: fixing the mass of the falling object to be 8.5±0.1 kg and the height to be 50±2.5 mm to obtain the maximum impact energy 5±0.5 J, so that the G value is only related to the shock absorption performance of the sole, and the formula is:

[0018] G = -F / mg = 2 + 2H / D + 2U F / mgD;

[0019] F: impact force; F = -F M , F M = 2mg + 2mgH / D + 2U F / D, the greater the deformation D value, the smaller F M .

[0020] Therefore, the shock absorption G value is related to the change in displacement after impact, and the greater the displacement deformation, the more the pressure is dispersed, and the lower the G value.

[0021] In order to obtain smaller force and larger deformation, the present application provides a foamed sole material formed by foaming EVA type material, which is specifically obtained by blending propylene glycol-2-ethylhexyl ester / clofibrate monomer copolymer rubber, directional hydrogenated SEBS, microcapsule expanding agent and reinforcing filler, and then foaming with EVA, POE, OBC, EPDM and other polymers. A foamed material with a shock absorption G value ≤8.0 and a rebound rate ≥60% is obtained. The foamed sole material uses microcapsule expanding agent and AC foaming agent together, which obtains special circular closed cells inside, and the circular cells produce larger deformation during movement, thereby greatly reducing the impact force, which is beneficial to the health of consumers, and has higher rebound, which improves the extreme experience of consumers during movement. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The internal cell morphology diagram of the foamed sole sample of Example 3;

[0023] Figure 2 The internal cell morphology diagram of the foamed sole of Comparative Example 6. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application. Unless otherwise specified, all reagents and raw materials used in the present application are commercially available or can be prepared by conventional methods.

[0025] The present application provides a foamed shoe sole material with low damping G value, which is prepared by foaming EVA material; the EVA material includes, in parts by weight, EVA 40-55 parts, acrylic-2-ethylhexyl ester / isononyl acid monoester copolymer rubber 5-15 parts, oriented hydrogenated SEBS 10-20 parts, POE 5-10 parts, EPDM 5-10 parts, OBC 5-10 parts, reinforcing filler 4-8 parts, microcapsule expanding agent 3-5 parts, crosslinking agent 0.5-0.8 parts, AC foaming agent 2-3 parts, zinc oxide 1-1.5 parts, stearic acid 0.5-1.2 parts, and stearate 0.5-1.3 parts.

[0026] The present application provides a foamed material for shoe sole, which has lower damping G value and higher resilience, and is beneficial to reduce impact force and the like in shoe application, and can improve the experience of consumers during exercise.

[0027] The foamed shoe sole material prepared by foaming the EVA material in the embodiments of the present application is a raw material composition containing polymers such as EVA, crosslinking agent, foaming agent, and additives, which takes EVA as the main component, and specifically includes the following components in parts by weight: 40-55 parts of EVA, 5-10 parts of POE, 5-10 parts of EPDM, 5-10 parts of OBC, 5-15 parts of acrylic-2-ethylhexyl ester / isononyl acid monoester copolymer rubber, and 10-20 parts of oriented hydrogenated SEBS.

[0028] EVA is the English abbreviation of ethylene-vinyl acetate copolymer, which is a high molecular resin copolymerized by ethylene and vinyl acetate VA, and generally has good elasticity. The EVA in the embodiments of the present application includes EVA with VA=18%-30%(mass percentage), and preferably commercially available varieties such as EVA 7470M (Taiwan Plastic Corporation); the parts by weight can be 40 parts, 45 parts, 50 parts, etc.

[0029] The English full name of POE is Polyolefin elastomer, which is mainly random polyethylene octene elastomer. Preferably, it includes a polyolefin elastomer brand with a crystallinity of ≤18%, and further preferably, commercially available varieties include: POE 8180 (Dow Chemical Company). In embodiments of the present application, the weight of the POE can be 5 parts, 8 parts, 10 parts, etc. The olefin block copolymer OBC includes a brand with a crystallinity of ≤15%, and the crystallinity can be 10-15%. Preferably, the variety is OBC 9107 (Dow Chemical Company, hardness 60A). In embodiments of the present application, the weight of the OBC can be 5 parts, 8 parts, 10 parts, etc.

[0030] Also, embodiments of the present application preferably use 5-7 parts by weight of EPDM. EPDM is the abbreviation of three-ethylene-propylene rubber, and three-ethylene-propylene elastomer is a three- component copolymer of ethylene, propylene and non-conjugated diene. In embodiments of the present application, the EPDM mainly includes a brand with a crystallinity of ≤5%, and preferably commercially available varieties include: EPDM 5565 (Dow Chemical Company), with a crystallinity of 1%.

[0031] In some embodiments of the present application, the EVA-based material formula includes 5 parts, 10 parts or 15 parts of 2-ethylhexyl acrylate / monoglyceride copolymer rubber, and 10 parts, 15 parts or 20 parts of oriented hydrogenated SEBS. The main monomer of the 2-ethylhexyl acrylate / monoglyceride copolymer rubber is 2-ethylhexyl acrylate, and the vulcanizing monomer is monoglyceride. The content of the vulcanizing monomer is preferably 4-5% of the copolymer elastomer, and preferably commercially available varieties include ACM-2212 (Jiujiang Duwei Rubber Technology Co., Ltd.), with a Mooney viscosity of 40±5 ML (1+4) 100℃. At the same time, embodiments of the present application use oriented hydrogenated SEBS with high styrene content, which preferably includes a block copolymer of styrene-butadiene-styrene with a styrene content of 35-40% and a hydrogenation degree of 50-80%, and preferably commercially available varieties include SEBS-Q5583, available from Zhejiang Zhongli Synthetic Materials Technology Co., Ltd. and the like. The hydrogenation degree refers to the mass fraction of partially hydrogenated butadiene in the material.

[0032] The embodiment of the present application selects to add materials with high damping performance in formula design. Specifically, according to the group contribution theory, the high polymer material with large volume, large quantity, large polarity of side groups on the molecular chain, and many intermolecular hydrogen bonds and strong intermolecular forces has large internal rotation activation energy and intermolecular force, large internal friction resistance of chain segment movement, and thus large hysteresis, large internal friction, and good damping performance. On the basis of the above-mentioned EVA matrix, the present application adds a proper amount of acrylic acid-2-ethylhexyl ester / monoglyceride copolymer rubber and high styrene content oriented hydrogenated SEBS. The acrylic acid-2-ethylhexyl ester / monoglyceride copolymer rubber contains polar carboxyl and ester bonds on the molecular chain, has many intermolecular hydrogen bonds and large force, and thus has large internal friction and good damping performance. In addition to the flexible and elastic butadiene segment in the molecular structure of the high styrene content oriented hydrogenated SEBS, the molecular chain also has a large volume of styrene side groups, and with the increase of the styrene content, the side group internal friction effect of the overall molecular structure is more obvious, and thus the damping performance is better. Moreover, the high styrene content oriented hydrogenated SEBS has better flexibility and adhesion than the high styrene content fully hydrogenated SEBS.

[0033] In addition to the above-mentioned polymer matrix component, the EVA material includes: 3-5 parts by weight of microcapsule expanding agent, 0.5-0.8 parts by weight of crosslinking agent, and 2-3 parts by weight of AC foaming agent. The AC foaming agent is azodicarbonamide, and a specific commercially available variety is AC3000H. As a preferred, the microcapsule expanding agent has a starting decomposition temperature of 118-128 DEG C and a maximum decomposition temperature of 172-187 DEG C; and an optional particle size of 18-24 μm, and a preferred variety is 909DU80 (Akzo Nobel Corporation). The crosslinking agent is preferably a peroxide crosslinking agent, and more preferably one of dicumyl peroxide and 1,4-bis-tert-butyl peroxide isopropyl benzene, and specific varieties are DCP and BIBP.

[0034] The embodiment of the present application can use low-temperature microcapsule expanding agent and AC foaming agent to obtain a special circular closed cell foaming sole material. The chemical foaming of the foaming sole of general sports shoes is to use AC foaming agent of azodicarbonamide to decompose nitrogen and a small amount of carbon dioxide at high temperature, and to use a proper amount of crosslinking agent to form a network structure in the microstructure of the material, so as to lock the gas in the material and form a foaming material. However, the foaming material prepared by the AC foaming agent has a closed microcell structure that cannot be seen by the naked eye, and the deformation is small under the same stress. In the embodiment of the present application, the low-temperature microcapsule expanding agent and the AC foaming agent are compounded, the low-temperature microcapsule expanding agent is first expanded into an elliptical or spherical shape under heat, and the microcapsule expanding agent, the AC foaming agent and the crosslinking agent act synchronously as the temperature further rises, the polymer matrix wraps the elliptical or spherical cell, and a three-dimensional network shell-core structure is formed. The core structure deforms under stress, and the shell structure has high elasticity and other mechanical properties. This special shell-core structure is beneficial to the large deformation of the foaming material under stress loading and the excellent recovery performance after the stress is unloaded.

[0035] Some preferred embodiments of the present application include, in parts by weight: 4-8 parts of activated sepiolite fiber powder, 1-1.5 parts of zinc oxide, 0.5-1.2 parts of stearic acid, and 0.5-1.3 parts of stearate; further including: 1.2 parts of zinc oxide, 1.0 parts of stearic acid, and 1.0 parts of zinc stearate.

[0036] Regarding the reinforcing filler, the activated sepiolite fiber powder with high strength is preferred in the present application, which is beneficial to improving the reinforcing performance. Sepiolite fiber is a fibrous variety of sepiolite mineral, which is called α-sepiolite. As a chain-like silicate mineral, sepiolite has a 2:1 type of layered structure unit, in which the two layers of silicon oxygen tetrahedron are sandwiched by a layer of magnesium oxygen octahedron. The tetrahedral layer is continuous, and the active oxygen in the layer periodically reverses direction. The octahedral layer forms a channel arranged alternately between the upper and lower layers. The Si-OH in the structure of sepiolite fiber can directly react with organic matter to form organic mineral derivatives. The activation reagent for activated and modified sepiolite fiber can be anhydride, coupling agent, etc. The activated sepiolite fiber powder after anhydride activation has improved functional group activity on the surface of sepiolite fiber and increased specific surface area, thereby achieving good reinforcing effect and significantly enhancing the tensile strength, bending strength and impact strength of the composite material.

[0037] Further preferably, the reinforcing filler comprises titanate coupling agent activated sepiolite fiber powder with an activation degree >80%; commercially available reinforcing fillers such as 1000 mesh activated sepiolite fiber powder from Hongsheng Chemical Co., Ltd. can be used in the present application. The activation degree is the degree of activation; in order to improve the dispersion performance of sepiolite and strengthen the interface adhesion between sepiolite and polymer, a coupling agent, a surface treatment agent or an acid is usually used to activate and modify the surface of sepiolite. The principle of modification is mainly to utilize the acid active center and active Si-OH group on the surface of sepiolite; through activation and modification, the surface energy can be reduced and the polarity of sepiolite can be changed. In addition, the preferred variety of zinc oxide is ZnO 997, which can play a lubricating and activating role with stearate and the like.

[0038] The present application also provides a preparation method of the foamed shoe sole material as described above, comprising the following steps:

[0039] The EVA material is sequentially mixed and granulated, and then at least foamed and formed once to obtain a foamed shoe sole material with low shock attenuation G value for sports shoes.

[0040] The present application is suitable for preparation by one-shot injection molding (IP process) or two-step die molding (MD process); the implementation steps of the IP process include: weighing, mixing, granulating, foaming and baking, and the specific contents are as follows:

[0041] Weighing: according to the amount of the formula, BIBP, AC foaming agent and microcapsule expanding agent are weighed as the first group; stearic acid, zinc stearate and zinc oxide are weighed as the second group; activated sepiolite fiber is weighed as the third group, and the remaining materials are weighed as the fourth group.

[0042] Mixing: first, pour the fourth group of materials into the mixing machine and turn on the machine, and mix for 10-15 minutes; preferably, when the temperature rises to 80-85℃, pour in the third group of materials; when the temperature rises to 90-95℃, pour in the second group of materials; when the temperature rises to 90-105℃, pour in the first group of materials, and mix for 3-5 minutes, then pour out the mixed materials.

[0043] Granulation: pour the mixed materials into the material making machine, and set the temperatures of the first, second, third and fourth zones to 80, 85, 90 and 95℃ respectively; and preferably, set the screw rotation speed to 40-50 revolutions per minute and the cutting speed to 15-20 revolutions per minute.

[0044] Foaming: pour the prepared granules into an injection foaming molding machine, set the temperatures of the first, second, third and fourth zones to 80, 85, 90 and 95℃ respectively, and preferably set the temperatures of the upper and lower mold plates of the molding mold to 170-175℃ and 170-175℃ respectively. Set the material amount according to the amount required by the mold, and the crosslinking and vulcanization time can be 480-600 seconds.

[0045] Baking: the first, second, third and fourth zone temperature of the oven can be adjusted to 80, 90, 95 and 100℃ respectively, and the rotation speed is preferably 60-70 revolutions per minute; the foamed material formed by foaming is sent into the oven, and the length of the oven is preferably 30-40 meters, and the baking time from the beginning to the end is preferably 30-40 minutes.

[0046] In other embodiments, the MD process implementation step includes: weighing → mixing → granulating → small foaming → secondary molding; the specific content of this implementation step is as follows:

[0047] Weighing: according to the amount of the formula, BIBP, AC foaming agent and microcapsule expanding agent can be weighed as the first group; stearic acid, zinc stearate and zinc oxide can be weighed as the second group; activated sepiolite fiber can be weighed as the third group, and the remaining materials can be weighed as the fourth group.

[0048] Mixing: first, pour the fourth group of materials into the mixer, turn on the machine, and mix for 10-15 minutes; preferably, when the temperature rises to 80-85℃, pour in the third group of materials; when the temperature rises to 90-95℃, pour in the second group of materials; when the temperature rises to 90-105℃, pour in the first group of materials, and mix for 3-5 minutes, then pour out the mixed materials.

[0049] Granulation: pour the mixed materials into the material making machine, and the first, second, third and fourth zone temperature is preferably adjusted to 80, 85, 90 and 95℃ respectively. Moreover, the screw rotation speed is preferably adjusted to 40-50 revolutions per minute, and the cutting speed is preferably adjusted to 15-20 revolutions per minute.

[0050] Small foaming: pour the prepared granules into the small foaming mold of the flat plate molding, complete the first foaming, and the foaming temperature is preferably 175℃; the foaming time can be 550-600 seconds.

[0051] Molding: after the small foaming semi-finished product is cooled for 24 hours, the small foaming semi-finished product is pressed into the flat plate molding mold to complete the molding of the finished product; the hot pressing temperature is preferably 175℃; the hot pressing time can be 400-420 seconds; after hot pressing, the sole is quickly placed in the mold for cooling, and the cooling water temperature can be 25℃, and the cooling time is 400-420 seconds.

[0052] In summary, the embodiment of the present application not only prepares a shoe sole foaming material with low damping G value by using 2-ethylhexyl acrylate / cinnamic acid monoester copolymer rubber, high styrene content oriented hydrogenated SEBS, sepiolite fiber and low-temperature microcapsule expanding agent, but also scientifically matches low crystallinity or high flexibility polymer in the formula to improve the resilience of the foaming material, etc., and finally obtains a foaming material with damping G value ≤8.0 and resilience ≥60%. The damping G value breaks the limit in the industry and realizes the lowest damping G value in the industry, which is the first in the industry.

[0053] In order to better illustrate the present application, the following will be further illustrated by examples.

[0054] Example 1

[0055] According to the amount of the formula in Table 1, BIBP, AC foaming agent and microcapsule expanding agent are weighed as the first group; stearic acid, zinc stearate and zinc oxide are weighed as the second group; activated sepiolite fiber is weighed as the third group, and the remaining materials are weighed as the fourth group.

[0056] First, pour the fourth group of materials into the mixer, turn on the machine and mix for 10-15 minutes, then pour in the third group of materials when the temperature rises to 80-85℃; pour in the second group of materials when the temperature rises to 90-95℃; pour in the first group of materials when the temperature rises to 90-100℃, and mix for 5 minutes before pouring out the mixed materials.

[0057] Pour the mixed materials into the material making machine, and adjust the temperatures of the first, second, third and fourth zones to 80, 85, 90 and 95℃ respectively; adjust the screw speed to 40-50 revolutions per minute, and adjust the cutting speed to 15-20 revolutions per minute.

[0058] Pour the prepared granules into a small foaming mold of a flat plate mold to complete the first foaming, and the foaming temperature is 175℃; the foaming time is 550-600 seconds.

[0059] After the small foaming semi-finished product is cooled for 24 hours, the small foaming semi-finished product is pressed into a flat plate mold to complete the finished product molding; the hot pressing temperature is 175℃; the hot pressing time is 400-420 seconds. After hot pressing, the shoe sole is quickly placed in the mold for cooling, and the cooling water temperature is 25℃, and the cooling time is 400-420 seconds.

[0060] Examples 2-7

[0061] According to the process steps of Example 1, the raw material formula is shown in Table 1.

[0062] Comparative Examples 1-7

[0063] The process steps of Example 1 were followed, with the exception of the formulation design, see Table 2.

[0064] The mechanical property data of the sole samples of the examples and comparative examples are also compared as follows.

[0065] Table 1 Formulation of Examples 1-7 of the present application

[0066]

[0067] Table 2 Formulation of Comparative Examples 1-7 of the present application

[0068]

[0069] The sources of raw materials are as follows:

[0070] ACM-2212: Mooney viscosity 40±5 ML (1+4) 100℃, Jiujiang Duwei Rubber Technology Co., Ltd.

[0071] SEBS-Q5583: Styrene content 39%, hydrogenation degree 50%, hardness 85A, Zhejiang Zhongli Synthetic Material Technology Co., Ltd.

[0072] Activated sepiolite fiber powder: mesh 1000 mesh, Hongsheng Chemical Co., Ltd.

[0073] EVA 7470M: Hardness 82A, VA content 26%, crystallinity 24.8%, Formosa Plastics Corporation.

[0074] POE 8180: Hardness 63A, crystallinity 16%, Dow Chemical Company.

[0075] EPDM 5565: Crystallinity 1%, Mooney viscosity 65 ML (1+4) 100℃, Dow Chemical Company.

[0076] OBC 9107: Crystallinity 10.6%, hardness 60A, Dow Chemical Company.

[0077] ZnO 997: Bai Shi brand zinc oxide, relative density 4.42-4.45, Quanzhou Xufeng Powder Raw Material Co., Ltd.

[0078] BIBP: Sinopec.

[0079] Stearic acid 1801: Indonesia Dukuda.

[0080] Zinc stearate: Huzhou Linghu Xingwang Chemical Co., Ltd.

[0081] Foaming agent AC 3000H: Hangzhou Haihong Fine Chemical Co., Ltd.

[0082] Microcapsule expanding agent 909DU80: AkzoNobel.

[0083] SOE L609: Hardness 76A, S content 33%, Asahi Kasei.

[0084] Talc: mesh 2000 mesh, Quanzhou Xufeng Powder Raw Material Co., Ltd.

[0085] Table 3 Sole performance data of the inventive comparative examples

[0086]

[0087] Table 4 Sole performance data of the inventive examples

[0088]

[0089] From the test results of Comparative Example 3 and Comparative Examples 1 and 2, and Comparative Example 6 and Example 3, it can be seen that the use of microcapsule expanding agent and AC foaming agent in combination has lower shock attenuation G value, higher rebound rate and lower compression deformation than the use of AC foaming agent alone, indicating that the microcapsule expanding agent and AC foaming agent are beneficial to the formation of a three-dimensional network shell-core structure in the foamed sole, the core structure produces large deformation under stress, which is beneficial to improving the shock attenuation performance; at the same time, the shell structure has high elasticity and high mechanics, and the recovery performance after force unloading is excellent, so it is also beneficial to improving the rebound of the foamed sole and improving the compression deformation.

[0090] From the test results of Comparative Example 8 and Example 3, it can be seen that compared with the use of microcapsule expanding agent alone and the use of microcapsule expanding agent + AC foaming agent in combination, the microcapsule expanding agent has a small gas generating amount, so the addition amount is large, and the addition amount needs to reach 5 times of the AC foaming agent to achieve the same foaming ratio. On the one hand, the use of microcapsule expanding agent alone will cause larger pores, and the interface strength between the pores will be poor, resulting in a large decrease in rebound performance / compression deformation / tensile strength / delamination tearing and other performances, and is not conducive to the recovery performance after force unloading. On the other hand, the use of expanding foaming agent alone requires more than 15 parts, and the price of the expanding agent reaches 120 yuan / kg, which is 5-10 times of other materials. Considering the cost of mass production, it is not recommended to use it alone.

[0091] From the test data of Comparative Examples 3, 4, 5 and Example 3, it can be seen that whether the addition of acrylic acid-2-ethylhexyl ester / cumene acid monoester copolymer rubber or the addition of high styrene content directional hydrogenated SEBS is beneficial to reducing the shock attenuation G value, but when both are used together, the shock attenuation G value decreases more obviously. It shows that whether a polymer with a polar molecular chain or a polymer with a bulky side group can improve the internal friction effect of the overall formula, reduce the shock attenuation G value, and improve the shock attenuation performance.

[0092] From the test data of Comparative Example 7 and Example 3, it can be seen that the rebound rate, delamination tear strength and tensile strength of the foamed shoe sole reinforced by activated sepiolite fiber are higher, and the shock attenuation G value and compression deformation are lower, thus indicating that the reinforcing effect of activated sepiolite fiber is better than that of talc powder.

[0093] From the test data of Examples 1-7, it can be seen that by adjusting the amount of acrylic acid-2-ethylhexyl ester / cumene acid monoester copolymer rubber to 5-15 parts, high-styrene-content oriented hydrogenated SEBS to 10-20 parts, EVA to 40-50 parts, POE to 5-10 parts, EPDM to 5-10 parts, OBC to 5-10 parts, and activated sepiolite fiber powder to 4-8 parts, and low-temperature microcapsule blowing agent to 2-5 parts, a foamed shoe sole with a shock attenuation G value of 7-8, a rebound rate of ≥60%, and mechanical properties meeting the requirements of sports shoe soles can be obtained. Moreover, increasing the amount of acrylic acid-2-ethylhexyl ester / cumene acid monoester copolymer rubber or high-styrene-content oriented hydrogenated SEBS is beneficial to reducing the shock attenuation G value. Meanwhile, increasing the amount of microcapsule blowing agent and sepiolite fiber can also improve the shock attenuation performance and compression deformation performance, while other mechanical properties only slightly decrease.

[0094] According to Figure 1 and Figure 2 From the internal cell of the foamed shoe soles of Example 3 and Comparative Example 6, it can be seen that the internal cell of the foamed shoe sole using AC foaming agent alone is small, and the internal cell of the foamed shoe sole using microcapsule blowing agent and AC foaming agent in combination presents a circular shape, which is a special cell with large deformation during loading and excellent recovery performance after unloading. These circular cells are beneficial to producing large deformation under stress, and the dense part between the cells contributes to the mechanics, so that the circular cell shape can be recovered after unloading.

[0095] Compared with existing EVA shock attenuation foaming materials, firstly, the low shock attenuation G value foamed shoe sole material prepared by the method described in the present patent has polar acid bonds and ester bonds in the molecular chain of acrylic acid-2-ethylhexyl ester / cumene acid monoester copolymer rubber and a large side group volume of high-styrene-content oriented hydrogenated SEBS added in the formula, which improves the internal friction effect of the overall formula, reduces the shock attenuation G value, and improves the shock attenuation performance. Secondly, by selecting high-strength sepiolite fiber powder activated by titanate, the activated sepiolite fiber powder has improved surface functional group activity and increased specific surface area, and better dispersibility. At the same time, the titanate component is beneficial to connecting acrylic acid-2-ethylhexyl ester / cumene acid monoester copolymer rubber, EVA and other polymers and activated sepiolite fiber powder, increasing the compatibility between the polymer matrix and the reinforcing filler, and the reinforcing effect is better than that of talc powder commonly selected in conventional EVA foamed shoe soles, which can significantly enhance the impact resistance of the foamed material, thus having innovation in the formula matching.

[0096] Compared with the existing EVA damping foaming material, the damping G value of the patent can be less than 8.0, breaking the technical bottleneck of damping G value ≥ 9.5 in the industry, while maintaining the high elasticity of the rebound rate ≥ 60%, and having excellent damping performance and rebound performance, which is the first in the industry.

[0097] By using low-temperature microcapsule expanding agent and AC foaming agent, a special closed circular cell with large deformation during loading and excellent recovery performance during unloading is obtained. During the foaming process, the low-temperature microcapsule expanding agent expands into an oval or spherical shape first. With further temperature rise, the microcapsule expanding agent, AC foaming agent and crosslinking agent act synchronously, and the polymer matrix wraps around the circular cell, forming a three-dimensional network shell structure-core structure. The core structure deforms under stress, while the shell structure has high elasticity and high mechanics. This special shell-core structure is beneficial to the foaming material to produce large deformation under stress loading and excellent recovery performance after unloading.

[0098] Overall, the patent obtains a foaming material with damping G value ≤ 8.0 and rebound rate ≥ 60% through formula matching and special cell structure design. The damping G value breaks the industry limit and realizes the lowest damping G value in the industry, while maintaining high elasticity. It has great market prospects in running shoes, basketball shoes and other categories of sports shoes.

[0099] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement or improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A foamed shoe sole material with low shock absorption G-value, characterized in that, The foamed sole material is obtained by foaming EVA-based materials; by weight, the EVA-based materials include: 40-55 parts EVA, 5-15 parts 2-ethylhexyl acrylate / itaconic acid monopolymer rubber, 10-20 parts directional hydrogenated SEBS, 5-10 parts POE, 5-10 parts EPDM, 5-10 parts OBC, 4-8 parts reinforcing filler, 3-5 parts microencapsulated expander, 0.5-0.8 parts crosslinking agent, 2-3 parts AC foaming agent, 1-1.5 parts zinc oxide, 0.5-1.2 parts stearic acid, and 0.5-1.3 parts stearate; the reinforcing filler is activated sepiolite fiber powder; The initial decomposition temperature of the microcapsule expander is 118-128℃, and the maximum decomposition temperature is 172-187℃.

2. The foamed shoe sole material according to claim 1, characterized in that, The styrene unit structure content of the directional hydrogenated SEBS is 35-40%, and the degree of hydrogenation is 50-80%.

3. The foamed shoe sole material according to claim 1, characterized in that, The reinforcing filler is activated sepiolite fiber powder treated with acid, acid anhydride, or coupling agent.

4. The foamed shoe sole material according to claim 3, characterized in that, The reinforcing filler is sepiolite fiber powder activated by titanate coupling agent, with an activation degree >80%.

5. The foamed shoe sole material according to any one of claims 1-4, characterized in that, The vinyl acetate unit structure content of the EVA is 18-30%.

6. The foamed shoe sole material according to claim 5, characterized in that, The crystallinity of the POE, EPDM and OBC is less than 18% respectively; The crosslinking agent is dicumyl peroxide and / or 1,4-di-tert-butylperoxide; the stearate is zinc stearate.

7. The foamed shoe sole material according to any one of claims 1-4, characterized in that, The shock absorption G-value of the foamed sole material is no greater than 8, and the rebound rate is above 60%.

8. The method for preparing the foamed shoe sole material according to any one of claims 1-7, characterized in that, Includes the following steps: The EVA material is sequentially mixed and granulated, and then foamed at least once to obtain a foamed sole material with low shock absorption G-value for sports shoes.

9. The preparation method according to claim 8, characterized in that, The mixing temperature is 80-110℃; the granulation temperature is 80-95℃.

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