Fast-rebound fatigue-resistant sole foaming composite material and preparation method thereof

Abstract

The invention belongs to the technical field of sole materials, and particularly relates to a quick-rebound fatigue-resistant sole foaming composite material and a preparation method thereof. According to the invention, the alpha-olefin ethylene copolymer and the modified ethylene-vinyl alcohol copolymer are mixed in an internal mixer, and hydroxyl groups of the modified ethylene-vinyl alcohol copolymer and the alpha-olefin ethylene copolymer form a hydrogen bond cross-linked network under the action of high-temperature shearing; a blend obtained through mixing, high-branching-degree polyolefin, modified nano-zinc oxide I and an auxiliary agent are added into a double-screw extruder for extrusion, the modified nano-zinc oxide is embedded into branching points of the high-branching-degree polyolefin, molecular chain slippage is limited through a pinning effect, the fatigue life of the composite material is prolonged, and the composite material is suitable for large-scale production. The preparation method comprises the following steps: preparing a foaming material, mixing the foaming material with azodicarbonamide, an antioxidant 1010 and the like, injecting the mixture into a supercritical device, effectively improving the density gradient, rebound resilience and mechanical properties through segmented pressure relief, and finally performing hot-pressing shaping to form the quick-rebound fatigue-resistant sole foaming composite material.

Description

Technical Field

[0001] The present invention belongs to the technical field of sole materials, and particularly relates to a fast-rebound and fatigue-resistant sole foaming composite material and a preparation method thereof. Background Art

[0002] With the continuous improvement of people's requirements for the performance of sports shoes, the performance of sole materials is also facing higher challenges. Traditional sole foaming materials have certain deficiencies in terms of rebound performance and fatigue resistance. After long-term use, problems such as deformation and decreased elasticity are likely to occur, affecting the wearing comfort and the service life of sports shoes.

[0003] Current sole materials mainly include EVA (ethylene-vinyl acetate copolymer), TPU (thermoplastic polyurethane), rubber, etc. EVA: Lightweight and easy to process, but it has problems such as hardening at low temperatures, poor puncture resistance, and low rebound rate. Permanent deformation is likely to occur after long-term compression (compression set rate ≥ 15%). TPU: High mechanical strength, but poor hydrolysis resistance, complex processing, and high density result in heavy soles (density > 0.3 g / cm 3 ). Rubber: Excellent wear resistance, but high density (> 1.0 g / cm 3 ), poor environmental friendliness, and reliance on the vulcanization process with high energy consumption. And in the prior art, although single material systems are lightweight, they lack strength, while composite structures have problems of density and process complexity.

[0004] For example, the patent with the application number CN202311188500.8 discloses a lightweight EVA composite chemical foaming sole material with a bimodal pore structure and a preparation method thereof. The method includes: S1. Mix 50 - 70 parts of ethylene-vinyl acetate, 10 - 25 parts of polyolefin thermoplastic elastomer, 20 - 40 parts of low molecular weight thermoplastic elastomer, wear-resistant agent and activator, and carry out melt homogenization granulation to obtain the first material; the low molecular weight thermoplastic elastomer is selected from one or more of polyurethane elastomer, polyester elastomer, and polyamide elastomer; S2. Mix the first material, chemical foaming agent, and crosslinking agent and then carry out granulation to obtain the second material; S3. Carry out injection pressure holding and cooling foaming on the second material; S4. Carry out secondary compression molding on the obtained small foaming semi-finished product to obtain the lightweight EVA composite chemical foaming sole material. The foaming sole prepared by the present invention has characteristics such as low specific gravity, high rebound, and small shrinkage, with controllable physical properties and good market prospects. This invention improves lightweight through a bimodal pore structure EVA composite material, but it relies on a complex secondary compression molding process, with low production efficiency, and does not solve the problem of long-term compression deformation.

[0005] In the prior art, although sole materials are constantly being improved, most are based on common rubber or ordinary polyolefin materials for modification, and it is difficult to achieve both fast rebound and excellent fatigue resistance at the same time.

[0006] Based on this, we propose a fast-rebound fatigue-resistant sole foaming composite material and its preparation method, hoping to solve the deficiencies in the existing technology. Summary of the Invention

[0007] The purpose of the present invention is to provide a fast-rebound fatigue-resistant sole foaming composite material and its preparation method for the existing problems.

[0008] The present invention is achieved through the following technical solutions:

[0009] A fast-rebound fatigue-resistant sole foaming composite material, comprising the following raw materials in parts by weight:

[0010] 70-90 parts of α-olefin ethylene copolymer, 30-40 parts of highly branched polyolefin, 6-10 parts of modified ethylene-vinyl alcohol copolymer, 5-7 parts of modified nano-zinc oxide, 2-3 parts of auxiliary agent, 3-5 parts of azodicarbonamide, 0.4-0.8 parts of antioxidant 1010, 1-2 parts of zinc stearate.

[0011] As a further technical solution, the preparation method of the modified ethylene-vinyl alcohol copolymer is as follows:

[0012] (1) Add ethylene-vinyl alcohol copolymer into a stirring tank, then weigh 0.05-0.15 times the mass of ethylene-vinyl alcohol copolymer of epoxy soybean oil and 0.001-0.005 times the mass of ethylene-vinyl alcohol copolymer of dibutyltin dilaurate and add them into the stirring tank, stir and mix evenly at 300-500 r / min, then transfer to a twin-screw extruder for melt reaction, the screw speed is 100-150 r / min, the reaction time is 6-8 min, and after the reaction is completed, granulate to obtain pre-modified ethylene-vinyl alcohol copolymer pellets for standby;

[0013] (2) Add the above-mentioned obtained pre-modified ethylene-vinyl alcohol copolymer pellets and xylene into a reaction kettle according to a ratio of 1 g:40-50 mL, stir at 80-90 °C and 200-300 r / min for 30-40 min, then mix acrylic butyl ester and benzoyl peroxide evenly according to a mass ratio of 1:0.01-0.03 and add them into the reaction kettle, stir and react at 80-90 °C and 200-300 r / min for 5-6 h, cool to room temperature after the reaction is completed, then pour into absolute ethanol and let stand for 5-10 h and then filter, collect the precipitate, wash it 2-3 times with absolute ethanol and 3-5 times with deionized water, and then place it in a vacuum drying oven and dry at 50-60 °C for 10-16 h.

[0014] As a further technical solution, the mass of the acrylic butyl ester in step (2) is 1-1.2 times that of the pre-modified ethylene-vinyl alcohol copolymer pellets.

[0015] As a further technical solution, the preparation of the modified nano zinc oxide includes the following steps:

[0016] 1) Ultrasonically disperse Fe 3 O 4 nano particles into Tris-HCl buffer solution. After ultrasonic dispersion is uniform, add dopamine hydrochloride with a mass 0.4 - 0.6 times that of the Fe 3 O 4 nano particles. After stirring at 200 - 300 r / min for 8 - 10 h, perform suction filtration. Wash with deionized water 3 - 4 times, then place in a vacuum drying oven and dry at 60 - 70 °C for 6 - 8 h to obtain pre-modified Fe 3 O 4 nano particles;

[0017] 2) Add polyethylene glycol and anhydrous dichloromethane to a round-bottom flask according to a mass-volume ratio of 1 g:15 - 20 mL. After stirring and mixing evenly, add succinic anhydride with a mass 0.03 - 0.04 times that of polyethylene glycol (5000 Da) and 4-dimethylaminopyridine with a mass 0.05 - 0.06 times that of polyethylene glycol. After stirring and mixing evenly, place in a water bath and heat to 50 - 60 °C for reaction for 6 - 8 h. After the reaction ends, cool the reaction solution to room temperature, then pour it into petroleum ether with a volume 3 - 5 times that of the reaction solution. The carboxylated polyethylene glycol precipitates out. Perform suction filtration to collect the precipitate, wash the precipitate with cold petroleum ether 3 - 4 times, and then place in a vacuum drying oven and dry at 50 - 60 °C for 8 - 10 h to obtain carboxylated polyethylene glycol;

[0018] 3) Ultrasonically disperse the pre-modified Fe 3 O 4 nano particles into deionized water. After dispersion is uniform, add erucic acid amide propyl dimethylamine with a mass 0.7 - 0.8 times that of the modified Fe 3 O 4 nano particles, continue ultrasonic treatment for 20 - 30 min, then add carboxylated polyethylene glycol with a mass 5 - 6 times that of the modified Fe 3 O 4 nano particles and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide / N-hydroxysuccinimide with a molar ratio of 1:2. After stirring and reacting at 100 - 200 r / min for 18 - 20 h, magnetically separate the product, wash it with absolute ethanol 2 - 3 times in sequence, then wash it with deionized water 3 - 4 times, and freeze-dry to obtain the modifier for use;

[0019] 4) Ultrasonically disperse the nano-zinc oxide powder in a 40% ethanol solution. After uniform dispersion, add the modifier and continue ultrasonic dispersion for 20 - 30 min. Then transfer it to a magnetic field reactor, apply a magnetic field intensity of 0.8 T and process for 10 - 20 min, and then cool to room temperature. Centrifuge at 8000 - 10000 r / min for 10 - 15 min, collect the precipitate, wash it with absolute ethanol 2 - 3 times and with deionized water 3 - 5 times successively, and then place it in a vacuum drying oven and dry it at 50 - 60 °C for 16 - 20 h.

[0020] As a further technical solution, the mass-to-volume ratio of the Fe 3 O 4 nano-particles to the Tris-HCl buffer solution is 1 g:100 - 120 mL.

[0021] As a further technical solution, the mass-to-volume ratio of the pre-modified Fe 3 O 4 nano-particles to deionized water is 1 g:100 - 120 mL;

[0022] The pre-cooling temperature for freeze-drying is -50 - -30 °C, pre-cool for 2 - 4 h, the drying temperature is 6 - 10 °C, and the drying time is 16 - 20 h.

[0023] As a further technical solution, the components and their corresponding weight parts in the auxiliary agent are: cerium stearate 6 - 10 parts, lanthanum stearate 4 - 6 parts, 2,2`-methylenebis(4-methyl-6-tert-butylphenol) 3 - 5 parts.

[0024] A preparation method of a fast-rebound fatigue-resistant sole foaming composite material, comprising the following steps:

[0025] S1. Weigh the corresponding weight parts of 70 - 90 parts of α-olefin ethylene copolymer, 30 - 40 parts of highly branched polyolefin, 6 - 10 parts of modified ethylene-vinyl alcohol copolymer, 5 - 7 parts of modified nano-zinc oxide, 2 - 3 parts of auxiliary agent, 3 - 5 parts of azodicarbonamide, 0.4 - 0.8 parts of antioxidant 1010, and 1 - 2 parts of zinc stearate for standby;

[0026] S2. Weigh and add the α-olefin ethylene copolymer and the modified ethylene-vinyl alcohol copolymer into a kneader, knead at 150 - 170 °C for 10 - 12 min, and the rotation speed of the kneader is 40 - 60 r / min to obtain a blend for standby;

[0027] S3. Divide the weighed modified nano-zinc oxide into two parts, namely modified nano-zinc oxide I and modified nano-zinc oxide II, with a mass ratio of 8:2. Add the obtained blend, highly branched polyolefin, modified nano-zinc oxide I, and additives into a twin-screw extruder for extrusion granulation to obtain masterbatch;

[0028] S4. Premix the masterbatch with azodicarbonamide, antioxidant 1010, stearic acid, and modified nano-zinc oxide II to obtain a mixture. Inject the mixture into a supercritical device, introduce CO2 until the pressure reaches 20 - 30 MPa, heat up to 90 - 110 °C, keep the temperature and pressure constant for 30 - 40 min, and then perform staged pressure relief to form a closed-cell foam with a gradient distribution of cell density;

[0029] S5. Place the closed-cell foam with a gradient distribution of cell density in a mold for hot pressing and shaping.

[0030] As a further technical solution, when the extruder in step S3 performs extrusion granulation, the temperature is controlled in stages: zone 1 is 160 °C, zone 2 is 180 °C, zone 3 is 190 °C, and the screw speed is 200 r / min.

[0031] As a further technical solution, the specific operation of staged pressure relief in step S4 is: first relieve the pressure to 10 MPa at a speed of 3 - 5 MPa / s, and then relieve the pressure to atmospheric pressure at a speed of 2 - 3 MPa / s.

[0032] The present invention has the following advantages compared with the prior art:

[0033] 1. The present invention provides a preparation method of a fast-rebound fatigue-resistant sole foaming composite material. Through the improvement of the raw materials and preparation process of the sole foaming material and the introduction of a gradient foaming process to optimize the cell structure, performance breakthroughs are achieved. The α-olefin ethylene copolymer and the modified ethylene-vinyl alcohol copolymer are kneaded in a mixer. The hydroxyl groups of the modified ethylene-vinyl alcohol copolymer form a hydrogen bond cross-linking network with the α-olefin ethylene copolymer under high-temperature shearing, and can also induce microphase separation to form EVOH dispersion, inhibiting cell collapse during the subsequent foaming process. The obtained blend is extruded in a twin-screw extruder together with a highly branched polyolefin, modified nano-zinc oxide I, and additives. The modified nano-zinc oxide is embedded at the branching points of the highly branched polyolefin, restricting the molecular chain slip through the pinning effect, reducing the fatigue crack propagation, and improving the fatigue life of the composite material. The addition of additives can inhibit the crystal form transformation and chemical property changes of nano-zinc oxide at high temperatures, prevent the surface of nano-zinc oxide from being oxidized, maintain its surface activity and structural stability, ensure that during processing and use, nano-zinc oxide can continuously and effectively reduce the fatigue crack propagation through the pinning effect, and guarantee the long-term stability of the material properties. Then, after blending with azodicarbonamide, antioxidant 1010, stearic acid, and modified nano-zinc oxide II, it is injected into a supercritical device. Rapid pressure relief induces the nucleation of small cells, and slow pressure relief allows gas diffusion to form large cells, achieving a density gradient, and effectively improving the resilience and mechanical properties. Finally, hot pressing and shaping are carried out. The hot pressing makes the cell wall thickness uniform, and the compression set is reduced to ≤7%, thereby forming a fast-rebound fatigue-resistant sole foaming composite material.

[0034] 2. In the present invention, under the catalytic action of dibutyltin dilaurate, the epoxy group of epoxidized soybean oil undergoes a ring-opening reaction with the hydroxyl group of the ethylene-vinyl alcohol copolymer, thereby introducing the molecular chain of epoxidized soybean oil onto the molecular chain of the ethylene-vinyl alcohol copolymer to achieve chemical bonding modification between the two, thereby improving the flexibility and plasticity of the ethylene-vinyl alcohol copolymer. Then, under the initiation of benzoyl peroxide, the carbon-carbon double bond on butyl acrylate undergoes a free radical polymerization reaction and a grafting reaction with the active sites on the molecular chain of the pre-modified ethylene-vinyl alcohol copolymer, thereby further improving the flexibility.

[0035] 3. The present invention first treats Fe 3 O 4 nanoparticles with dopamine hydrochloride to form a dopamine layer on the surface of Fe 3 O 4 . The dopamine layer on the surface can provide abundant catechol / amino active sites, enhancing the subsequent coupling effect; then, the polyethylene glycol is carboxylated and activated. The carboxylation provides active sites for the subsequent amidation reaction with erucamide propyl dimethylamine. In a specific reaction system, magnetic Fe 3 O 4A composite modifier formed by chemically grafting nanoparticles with carboxylated polyethylene glycol. When this modifier is used in the modification of nano-zinc oxide, it can replace the traditional silane coupling agent. Under the action of an ultrasonic field, it promotes the dispersion of nano-zinc oxide and the adsorption of modifier molecules on its surface. At the same time, a magnetic field is applied to align magnetic nanoparticles on the surface of nano-zinc oxide, and then the reaction temperature is controlled by a thermal field to promote the interaction between the modifier and nano-zinc oxide, such as chemical bonding or physical entanglement. These changes transform the surface of nano-zinc oxide from a state of poor compatibility with the matrix material to a state with better interaction with polyolefins, thereby improving its dispersibility and interfacial bonding force in the matrix. This synergistic effect enables the modified nano-zinc oxide to better exert its reinforcing effect when mixed with highly branched polyolefins, improving the comprehensive properties of the material.

[0036] 4. The modified nano-zinc oxide of the present invention can also be used as a nucleating agent. During the supercritical foaming process, supercritical fluid CO 2 dissolves in the polymer matrix. The surface roughness and high surface energy of the modified nano-zinc oxide provide preferential adsorption and nucleation sites for gas molecules, reducing the energy barrier required for nucleation and promoting cell formation. In addition, the modification treatment not only improves the dispersibility of nano-zinc oxide but also may interact with polymer chains through hydrogen bonds or van der Waals forces to form local micro-region structures, further guiding the growth direction of cells and inhibiting cell coalescence. The pore-piercing effect of nano-zinc oxide can inhibit the excessive movement of polymer segments, reducing the risk of cell collapse or rupture, thereby improving the uniformity and stability of the cell structure. Detailed implementation manners

[0037] To further explain the present invention, the following specific embodiments are described below.

[0038] Example 1

[0039] A preparation method of a fast-rebound fatigue-resistant sole foaming composite material includes the following steps:

[0040] S1. Weigh 70 parts of an α-olefin ethylene copolymer, 30 parts of a highly branched polyolefin, 6 parts of a modified ethylene-vinyl alcohol copolymer, 5 parts of modified nano-zinc oxide, 2 parts of an additive, 3 parts of azodicarbonamide, 0.4 part of antioxidant 1010, and 1 part of zinc stearate for standby;

[0041] S2. Weigh and add the α-olefin ethylene copolymer and the modified ethylene-vinyl alcohol copolymer into a kneader, knead at 150 °C for 10 min, and the rotation speed of the kneader is 40 r / min to obtain a blend for standby;

[0042] S3. Divide the weighed modified nano-zinc oxide into two parts, namely modified nano-zinc oxide I and modified nano-zinc oxide II, with a mass ratio of 8:2. Add the obtained blend, highly branched polyolefin, modified nano-zinc oxide I, and additives into a twin-screw extruder for extrusion granulation to obtain masterbatch. The temperature is controlled in sections: 160 °C in zone 1, 180 °C in zone 2, 190 °C in zone 3, and the screw speed is 200 r / min;

[0043] S4. Premix the masterbatch with azodicarbonamide, antioxidant 1010, stearic acid, and modified nano-zinc oxide II to obtain a mixture. Inject the mixture into a supercritical device, introduce CO 2 until the pressure reaches 20 MPa, heat up to 90 °C, keep the temperature and pressure constant for 30 min, then release the pressure at a rate of 3 MPa / s to 10 MPa, and then release the pressure at a rate of 2 MPa / s to atmospheric pressure to form a closed-cell foaming body with a gradient distribution of cell density;

[0044] S5. Place the closed-cell foaming body with a gradient distribution of cell density in a mold for hot pressing and shaping;

[0045] The preparation method of the modified ethylene-vinyl alcohol copolymer is as follows:

[0046] (1) Add the ethylene-vinyl alcohol copolymer into a stirring tank, then weigh 0.05 times the mass of the ethylene-vinyl alcohol copolymer of epoxy soybean oil and 0.001 times the mass of the ethylene-vinyl alcohol copolymer of dibutyltin dilaurate and add them into the stirring tank. Stir and mix evenly at 300 r / min, then transfer to a twin-screw extruder for melt reaction. The screw speed is 100 r / min, the reaction time is 6 min. After the reaction, granulate to obtain pre-modified ethylene-vinyl alcohol copolymer pellets for standby;

[0047] (2) Add the above-obtained pre-modified ethylene-vinyl alcohol copolymer pellets and xylene into a reaction kettle according to a ratio of 1 g:40 mL, stir at 80 °C and 200 r / min for 30 min, then mix butyl acrylate and benzoyl peroxide evenly according to a mass ratio of 1:0.01 and add them into the reaction kettle. The mass of butyl acrylate is 1 time that of the pre-modified ethylene-vinyl alcohol copolymer pellets. Stir and react at 80 °C and 200 r / min for 5 h. After the reaction, cool to room temperature, then pour into absolute ethanol and let it stand for 5 - 10 h and then filter. Collect the precipitate, wash it twice with absolute ethanol and three times with deionized water, then place it in a vacuum drying oven and dry at 50 °C for 10 h;

[0048] The preparation of the modified nano-zinc oxide includes the following steps:

[0049] 1) Add Fe 3 O 4The nanoparticles were ultrasonically dispersed into Tris-HCl buffer solution, and Fe 3 O 4 The mass-volume ratio of the nanoparticles to Tris-HCl buffer solution was 1 g:100 mL. After ultrasonic dispersion was uniform, dopamine hydrochloride 0.4 times the mass of the Fe 3 O 4 nanoparticles was added. After stirring at 200 r / min for 8 h, filtration was carried out. After washing with deionized water 3 times, it was placed in a vacuum drying oven and dried at 60 °C for 6 h to obtain pre-modified Fe 3 O 4 nanoparticles;

[0050] 2) Polyethylene glycol and anhydrous dichloromethane were added to a round-bottom flask according to a mass-volume ratio of 1 g:15 mL. After stirring and mixing evenly, succinic anhydride 0.03 times the mass of polyethylene glycol and 4-dimethylaminopyridine 0.05 times the mass of polyethylene glycol were added. After stirring and mixing evenly, it was placed in a water bath and heated to 50 °C for reaction for 6 h. After the reaction ended, the reaction solution was cooled to room temperature, and then poured into petroleum ether 3 times the volume of the reaction solution. Carboxylated polyethylene glycol precipitated out. The precipitate was collected by filtration, and then washed with cold petroleum ether 3 times and placed in a vacuum drying oven and dried at 50 °C for 8 h to obtain carboxylated polyethylene glycol;

[0051] 3) The pre-modified Fe 3 O 4 nanoparticles were ultrasonically dispersed into deionized water. The mass-volume ratio of the pre-modified Fe 3 O 4 nanoparticles to deionized water was 1 g:100 mL. After dispersion was uniform, erucylamidopropyl dimethylamine 0.7 times the mass of the modified Fe 3 O 4 nanoparticles was added, and ultrasonic treatment was continued for 20 min. Then, carboxylated polyethylene glycol 5 - 6 times the mass of the modified Fe 3 O 4 nanoparticles and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide / N-hydroxysuccinimide with a molar ratio of 1:2 were added. After stirring and reacting at 100 r / min for 18 h, the product was magnetically separated, washed with absolute ethanol 2 times in sequence, then washed with deionized water 3 times, and freeze-dried to obtain the modifier for use;

[0052] The pre-cooling temperature of the freeze-drying was -50 °C, pre-cooling for 2 h, the drying temperature was 6 °C, and the drying time was 16 h;

[0053] 4) Ultrasonically disperse the nano-zinc oxide powder in a 40% ethanol solution. After uniform dispersion, add the modifier, continue ultrasonic dispersion for 20 min, then transfer it to a magnetic field reactor, apply a magnetic field intensity of 0.8 T for 10 min, cool to room temperature, centrifuge at 8000 r / min for 10 min, collect the precipitate, wash it twice with absolute ethanol and three times with deionized water, and then place it in a vacuum drying oven and dry it at 50 °C for 16 h;

[0054] The components and corresponding parts by weight of the said auxiliary agent are: 6 parts of cerium stearate, 4 parts of lanthanum stearate, and 3 parts of 2,2`-methylenebis(4-methyl-6-tert-butylphenol).

[0055] Example 2

[0056] A preparation method of a fast-rebound fatigue-resistant sole foaming composite material, comprising the following steps:

[0057] S1. Weigh 80 parts of α-olefin ethylene copolymer, 35 parts of highly branched polyolefin, 8 parts of modified ethylene-vinyl alcohol copolymer, 6 parts of modified nano-zinc oxide, 2.5 parts of auxiliary agent, 4 parts of azodicarbonamide, 0.6 part of antioxidant 1010, and 1.5 parts of zinc stearate for standby;

[0058] S2. Weigh and add the α-olefin ethylene copolymer and the modified ethylene-vinyl alcohol copolymer into a kneader, knead at 160 °C for 11 min, and the rotation speed of the kneader is 50 r / min to obtain a blend for standby;

[0059] S3. Divide the weighed modified nano-zinc oxide into two parts, namely modified nano-zinc oxide Ⅰ and modified nano-zinc oxide Ⅱ, and the mass ratio of modified nano-zinc oxide Ⅰ to modified nano-zinc oxide Ⅱ is 8:2. Add the obtained blend, highly branched polyolefin, modified nano-zinc oxide Ⅰ, and auxiliary agent into a twin-screw extruder for extrusion granulation to obtain masterbatch, and control the temperature in sections: 160 °C in zone 1, 180 °C in zone 2, 190 °C in zone 3, and the screw rotation speed is 200 r / min;

[0060] S4. Premix the masterbatch with azodicarbonamide, antioxidant 1010, stearic acid, and modified nano-zinc oxide Ⅱ to obtain a mixture, inject the mixture into a supercritical device, introduce CO 2 to a pressure of 25 MPa, raise the temperature to 100 °C, keep the temperature and pressure constant for 35 min, first depressurize at a speed of 4 MPa / s to 10 MPa, and then depressurize to atmospheric pressure at a speed of 2.5 MPa / s to form a closed-cell foam with a gradient distribution of cell density;

[0061] S5. Place the closed-cell foam with a gradient distribution of cell density in a mold for hot pressing and shaping;

[0062] The preparation method of the modified ethylene-vinyl alcohol copolymer is as follows:

[0063] (1) Add the ethylene-vinyl alcohol copolymer into a stirring tank, then weigh 0.1 times the mass of the ethylene-vinyl alcohol copolymer of epoxidized soybean oil and 0.003 times the mass of the ethylene-vinyl alcohol copolymer of dibutyltin dilaurate and add them into the stirring tank. Stir and mix evenly at 400 r / min, then transfer to a twin-screw extruder for melt reaction. The screw speed is 125 r / min, the reaction time is 7 min. After the reaction, granulate to obtain pre-modified ethylene-vinyl alcohol copolymer pellets for standby;

[0064] (2) Add the pre-modified ethylene-vinyl alcohol copolymer pellets obtained above and xylene into a reaction kettle according to the ratio of 1 g:45 mL, stir at 85 °C and 250 r / min for 35 min, then mix butyl acrylate and benzoyl peroxide evenly according to the mass ratio of 1:0.02 and add them into the reaction kettle. The mass of butyl acrylate is 1.1 times that of the pre-modified ethylene-vinyl alcohol copolymer pellets. Stir and react at 85 °C and 250 r / min for 5.5 h. After the reaction, cool to room temperature, then introduce into absolute ethanol and let stand for 8 h, then filter. Collect the precipitate and wash it 2 times with absolute ethanol and 4 times with deionized water, then place it in a vacuum drying oven and dry at 55 °C for 13 h;

[0065] The preparation of the modified nano-zinc oxide includes the following steps:

[0066] 1) Ultrasonically disperse Fe 3 O 4 nano-particles into Tris-HCl buffer solution. The mass-volume ratio of Fe 3 O 4 nano-particles to Tris-HCl buffer solution is 1 g:110 mL. After ultrasonic dispersion is uniform, add 0.5 times the mass of Fe 3 O 4 nano-particles of dopamine hydrochloride, stir at 250 r / min for 9 h, then filter by suction, wash 3 times with deionized water, then place it in a vacuum drying oven and dry at 65 °C for 7 h to obtain pre-modified Fe 3 O 4 nano-particles;

[0067] 2) Add polyethylene glycol and anhydrous dichloromethane into a round-bottom flask according to the mass-volume ratio of 1 g:17 mL. After stirring and mixing evenly, add succinic anhydride with a mass 0.035 times that of polyethylene glycol and 4-dimethylaminopyridine with a mass 0.055 times that of polyethylene glycol. After stirring and mixing evenly, place it in a water bath, heat up to 55 °C and react for 7 h. After the reaction is completed, cool the reaction solution to room temperature, then pour it into petroleum ether with a volume 4 times that of the reaction solution. The carboxylated polyethylene glycol precipitates out. Filter and collect the precipitate, wash the precipitate with cold petroleum ether 3.5 times, and then place it in a vacuum drying oven. Dry it at 55 °C for 9 h to obtain carboxylated polyethylene glycol;

[0068] 3) Ultrasonically disperse the pre-modified Fe 3 O 4 nanoparticles in deionized water. The mass-volume ratio of the pre-modified Fe 3 O 4 nanoparticles to deionized water is 1 g:110 mL. After dispersing evenly, add erucylamidopropyl dimethylamine with a mass 0.75 times that of the modified Fe 3 O 4 nanoparticles, continue ultrasonic treatment for 25 min, and then add carboxylated polyethylene glycol with a mass 5.5 times that of the modified Fe 3 O 4 nanoparticles and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide / N-hydroxysuccinimide with a molar ratio of 1:2. After stirring and reacting at 150 r / min for 19 h, magnetically separate the product, wash it with absolute ethanol 3 times in sequence, then wash it with deionized water 3 times, and then freeze-dry to obtain the modifier for use;

[0069] The pre-cooling temperature for the freeze-drying is -40 °C, pre-cool for 3 h, the drying temperature is 8 °C, and the drying time is 18 h;

[0070] 4) Ultrasonically disperse the nano-zinc oxide powder in a 40% ethanol solution. After dispersing evenly, add the modifier, continue ultrasonic dispersion for 25 min, then transfer it to a magnetic field reactor, apply a magnetic field intensity of 0.8 T and process for 15 min, then cool to room temperature. Centrifuge at 9000 r / min for 12 min, collect the precipitate, wash it with absolute ethanol 3 times in sequence, wash it with deionized water 4 times, and then place it in a vacuum drying oven. Dry it at 55 °C for 18 h to obtain the product;

[0071] The components and corresponding weight parts in the auxiliary agent are: cerium stearate 8 parts, lanthanum stearate 5 parts, 2,2`-methylenebis(4-methyl-6-tert-butylphenol) 4 parts.

[0072] Example 3

[0073] A preparation method of a fast-rebound fatigue-resistant sole foaming composite material, comprising the following steps:

[0074] S1. Weigh 90 parts of α-olefin ethylene copolymer, 40 parts of highly branched polyolefin, 10 parts of modified ethylene-vinyl alcohol copolymer, 7 parts of modified nano-zinc oxide, 3 parts of additives, 5 parts of azodicarbonamide, 0.8 part of antioxidant 1010, and 2 parts of zinc stearate for standby;

[0075] S2. Weigh and add the α-olefin ethylene copolymer and the modified ethylene-vinyl alcohol copolymer into a kneader, knead at 170 °C for 12 min, and the rotation speed of the kneader is 60 r / min to obtain a blend for standby;

[0076] S3. Divide the weighed modified nano-zinc oxide into two parts, namely modified nano-zinc oxide I and modified nano-zinc oxide II, and the mass ratio of modified nano-zinc oxide I to modified nano-zinc oxide II is 8:2. Add the obtained blend, highly branched polyolefin, modified nano-zinc oxide I, and additives into a twin-screw extruder for extrusion granulation to obtain masterbatch. The temperature is controlled in sections: 160 °C in zone 1, 180 °C in zone 2, 190 °C in zone 3, and the screw rotation speed is 200 r / min;

[0077] S4. Premix the masterbatch with azodicarbonamide, antioxidant 1010, stearic acid, and modified nano-zinc oxide II to obtain a mixture. Inject the mixture into a supercritical device, introduce CO 2 until the pressure reaches 30 MPa, raise the temperature to 110 °C, keep the temperature and pressure constant for 40 min, then release the pressure at a speed of 5 MPa / s to 10 MPa, and then release the pressure at a speed of 3 MPa / s to atmospheric pressure to form a closed-cell foam with a gradient distribution of cell density;

[0078] S5. Place the closed-cell foam with a gradient distribution of cell density in a mold for hot pressing and shaping;

[0079] The preparation method of the modified ethylene-vinyl alcohol copolymer is as follows:

[0080] (1) Add the ethylene-vinyl alcohol copolymer into a stirring tank, then weigh 0.15 times the mass of the ethylene-vinyl alcohol copolymer of epoxy soybean oil and 0.005 times the mass of the ethylene-vinyl alcohol copolymer of dibutyltin dilaurate and add them into the stirring tank. Stir and mix evenly at 500 r / min, then transfer to a twin-screw extruder for melt reaction. The screw rotation speed is 150 r / min, and the reaction time is 8 min. After the reaction, granulate to obtain pre-modified ethylene-vinyl alcohol copolymer pellets for standby;

[0081] (2) Add the obtained pre-modified ethylene-vinyl alcohol copolymer pellets and xylene to the reaction kettle at a ratio of 1 g:50 mL, stir at 90 °C and 300 r / min for 40 min, then mix butyl acrylate and benzoyl peroxide evenly according to a mass ratio of 1:0.03 and add them to the reaction kettle. The mass of butyl acrylate is 1.2 times that of the pre-modified ethylene-vinyl alcohol copolymer pellets. Stir and react at 90 °C and 300 r / min for 6 h. After the reaction, cool to room temperature, then introduce it into absolute ethanol, let it stand for 10 h and then filter. Collect the precipitate and wash it 3 times with absolute ethanol and 5 times with deionized water successively, and then place it in a vacuum drying oven and dry it at 60 °C for 16 h;

[0082] The preparation of the modified nano-zinc oxide includes the following steps:

[0083] 1) Ultrasonically disperse Fe 3 O 4 nano-particles into Tris-HCl buffer solution. The mass-volume ratio of Fe 3 O 4 nano-particles to Tris-HCl buffer solution is 1 g:120 mL. After ultrasonic dispersion is uniform, add dopamine hydrochloride 0.6 times the mass of Fe 3 O 4 nano-particles. Stir at 300 r / min for 10 h, then filter by suction. Wash with deionized water 4 times, and then place it in a vacuum drying oven and dry it at 70 °C for 8 h to obtain pre-modified Fe 3 O 4 nano-particles;

[0084] 2) Add polyethylene glycol and anhydrous dichloromethane to a round-bottom flask at a mass-volume ratio of 1 g:20 mL. After stirring and mixing evenly, add succinic anhydride 0.04 times the mass of polyethylene glycol and 4-dimethylaminopyridine 0.06 times the mass of polyethylene glycol. After stirring and mixing evenly, place it in a water bath and heat to 60 °C for reaction for 8 h. After the reaction, cool the reaction solution to room temperature, and then pour it into petroleum ether 5 times the volume of the reaction solution. The carboxylated polyethylene glycol precipitates. Filter by suction to collect the precipitate, and then wash the precipitate 4 times with cold petroleum ether and place it in a vacuum drying oven and dry it at 60 °C for 10 h to obtain carboxylated polyethylene glycol;

[0085] 3) Ultrasonically disperse the pre-modified Fe 3 O 4 nano-particles into deionized water. The mass-volume ratio of the pre-modified Fe 3 O 4 nano-particles to deionized water is 1 g:120 mL. After dispersion is uniform, add modified Fe 3 O 4Erucamide propyl dimethylamine, which is 0.8 times the mass of the nanoparticles, is continuously ultrasonically treated for 30 min, and then modified Fe 3 O 4 Carboxylated polyethylene glycol, which is 6 times the mass of the nanoparticles, and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide / N-hydroxysuccinimide with a molar ratio of 1:2 are added. After stirring and reacting at 200 r / min for 20 h, the product is magnetically separated, washed 3 times with absolute ethanol in sequence, then washed 4 times with deionized water, and freeze-dried to obtain the modifier for later use;

[0086] The pre-cooling temperature for the freeze-drying is -30 °C, pre-cooling for 4 h, the drying temperature is 10 °C, and the drying time is 20 h;

[0087] 4) Ultrasonically disperse the nano-zinc oxide powder in a 40% ethanol solution. After uniform dispersion, add the modifier, continue ultrasonic dispersion for 30 min, then transfer to a magnetic field reactor, apply a magnetic field intensity of 0.8 T for 20 min, and then cool to room temperature. After centrifuging at 10000 r / min for 15 min, collect the precipitate, wash it 3 times with absolute ethanol in sequence, wash it 5 times with deionized water, and then place it in a vacuum drying oven and dry it at 60 °C for 20 h;

[0088] The components and corresponding weight parts in the said auxiliary agent are: cerium stearate 10 parts, lanthanum stearate 6 parts, 2,2`-methylenebis(4-methyl-6-tert-butylphenol) 5 parts.

[0089] Comparative Example 1

[0090] Compared with Example 2 in this Comparative Example 1, the modified ethylene-vinyl alcohol copolymer is replaced with an unmodified ethylene-vinyl alcohol copolymer, and the rest of the technical solutions are the same as those in Example 2.

[0091] Comparative Example 2

[0092] Compared with Example 2 in this Comparative Example 2, the modified nano-zinc oxide is replaced with an unmodified nano-zinc oxide, and the rest of the technical solutions are the same as those in Example 2.

[0093] Comparative Example 3

[0094] Compared with Example 2 in this Comparative Example 3, no auxiliary agent is added, and the rest of the technical solutions are the same as those in Example 2.

[0095] Comparative Example 4

[0096] Compared with Example 2 in this Comparative Example 4, the modified nano-zinc oxide weighed in step S1 is added to step S3 at one time, and the addition of the modified nano-zinc oxide is not carried out in step S4, and the rest of the technical solutions are the same as those in Example 2.

[0097] Comparative Example 5

[0098] Compared with Example 2, in this Comparative Example 5, in step S4, staged pressure relief is not carried out, and the pressure is directly relieved to atmospheric pressure at a rate of 3 - 5 MPa / s, and the rest of the technical solutions are the same as those of Example 2.

[0099] Performance Test

[0100] The performance tests were respectively carried out on the sole foaming composites prepared in each example and comparative example, and the test results are shown in Table 1 below.

[0101] Table 1

[0102]

[0103] It can be seen from Table 1 above that the fast - rebound and fatigue - resistant sole foaming composite material prepared by the method of the present invention has the advantages of low density, high tensile strength, good resilience, and low compression set.

[0104] The above - mentioned are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A fast-rebound and fatigue-resistant sole foam composite material, characterized in that: The invention comprises the following raw materials in parts by weight: 70-90 parts of α-olefin ethylene copolymer, 30-40 parts of high-branched polyolefin, 6-10 parts of modified ethylene-vinyl alcohol copolymer, 5-7 parts of modified nano zinc oxide, 2-3 parts of additives, 12-16 parts of supercritical CO2, 3-5 parts of azodicarbonamide, 0.4-0.8 parts of antioxidant 1010, and 1-2 parts of zinc stearate.

2. The fast-rebound and fatigue-resistant sole foam composite material according to claim 1, characterized in that: The preparation method of the modified ethylene-vinyl alcohol copolymer is: (1) adding ethylene-vinyl alcohol copolymer to a stirring tank, then weighing 0.05-0.15 times the mass of ethylene-vinyl alcohol copolymer epoxy soybean oil and 0.001-0.005 times the mass of ethylene-vinyl alcohol copolymer dibutyltin dilaurate and adding them to the stirring tank, stirring and mixing at 300-500 r / min, and then transferring to a twin-screw extruder for melt reaction, the screw speed is 100-150 r / min, the reaction time is 6-8 min, and after the reaction is completed, granulation is performed to obtain pre-modified ethylene-vinyl alcohol copolymer pellets for use; (2) The pre-modified ethylene-vinyl alcohol copolymer pellets obtained above and xylene are added to a reactor at a ratio of 1 g:40-50 mL, and stirred at 80-90° C. and 200-300 r / min for 30-40 min. Then, butyl acrylate and benzoyl peroxide are mixed in a mass ratio of 1:0.01-0.03 and added to the reactor. The mixture is stirred at 80-90° C. and 200-300 r / min for 5-6 h. After the reaction is completed, the mixture is cooled to room temperature, poured into anhydrous ethanol, allowed to stand for 5-10 h, and then filtered. The precipitate is collected, washed with anhydrous ethanol 2-3 times, washed with deionized water 3-5 times, and then placed in a vacuum drying oven and dried at 50-60° C. for 10-16 h.

3. The fast-rebound and fatigue-resistant sole foam composite material according to claim 1, characterized in that: The mass of the butyl acrylate described in step (2) is 1 to 1.2 times that of the pre-modified ethylene-vinyl alcohol copolymer pellets.

4. The fast-rebound and fatigue-resistant sole foam composite material according to claim 1, characterized in that: The preparation of the modified nano zinc oxide comprises the following steps: 1) Ultrasonic dispersion of Fe3O4 nanoparticles in Tris-HCl buffer, after uniform ultrasonic dispersion, adding dopamine hydrochloride of 0.4 to 0.6 times the mass of Fe3O4 nanoparticles, stirring at 200 to 300 r / min for 8 to 10 hours, filtering, washing with deionized water for 3 to 4 times, placing in a vacuum drying oven, and drying at 60 to 70° C. for 6 to 8 hours to obtain pre-modified Fe3O4 nanoparticles; 2) Add polyethylene glycol and anhydrous dichloromethane to a round-bottom flask at a mass volume ratio of 1 g:15-20 mL, stir and mix, add succinic anhydride 0.03-0.04 times the mass of polyethylene glycol and 4-dimethylaminopyridine 0.05-0.06 times the mass of polyethylene glycol, stir and mix, place in a water bath, heat to 50-60° C. and react for 6-8 hours. After the reaction, cool the reaction solution to room temperature, then pour into petroleum ether 3-5 times the volume of the reaction solution, carboxylated polyethylene glycol precipitates, collect the precipitate by suction, wash the precipitate with cold petroleum ether 3-4 times, place in a vacuum drying oven, and dry at 50-60° C. for 8-10 hours to obtain carboxylated polyethylene glycol; 3) Ultrasonic dispersion of pre-modified Fe3O4 nanoparticles in deionized water, after uniform dispersion, add 0.7-0.8 times the mass of modified Fe3O4 nanoparticles of erucic acid amide propyl dimethylamine, continue ultrasonic treatment for 20-30 minutes, then add 5-6 times the mass of modified Fe3O4 nanoparticles of carboxylated polyethylene glycol and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide / N-hydroxysuccinimide in a molar ratio of 1:2, stir at 100-200 r / min for 18-20 hours, magnetically separate the product, wash with anhydrous ethanol 2-3 times, wash with deionized water 3-4 times, and freeze-dry to obtain the modifier for standby use; 4) Ultrasonic dispersion of nano zinc oxide powder in 40% ethanol solution, adding modifier after uniform dispersion, continuing ultrasonic dispersion for 20 to 30 minutes, transferring to a magnetic field reactor, applying a magnetic field strength of 0.8 T for 10 to 20 minutes, cooling to room temperature, centrifuging at 8000 to 10000 r / min for 10 to 15 minutes, collecting the precipitate, washing it with anhydrous ethanol for 2 to 3 times, washing it with deionized water for 3 to 5 times, placing it in a vacuum drying oven, and drying it at 50 to 60° C. for 16 to 20 hours.

5. The fast-rebound and fatigue-resistant sole foam composite material according to claim 4, characterized in that: The mass volume ratio of the Fe3O4 nanoparticles and the Tris-HCl buffer described in step 1) is 1 g: 100-120 mL.

6. The fast-rebound and fatigue-resistant sole foam composite material according to claim 4, characterized in that: The mass volume ratio of the pre-modified Fe3O4 nanoparticles and deionized water described in step 3) is 1g:100-120mL; The precooling temperature of the freeze drying is -50 to -30°C, the precooling time is 2 to 4 hours, the drying temperature is 6 to 10°C, and the drying time is 16 to 20 hours.

7. The fast-rebound and fatigue-resistant sole foam composite material according to claim 1, characterized in that: The components and corresponding weight parts in the auxiliary agent are: 6-10 parts of cerium stearate, 4-6 parts of lanthanum stearate, and 3-5 parts of 2,2'-methylenebis(4-methyl-6-tert-butylphenol).

8. The method for preparing the fast-rebound and fatigue-resistant foam composite material for shoe soles according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1, weigh corresponding weight portions of α-olefin ethylene copolymer 70-90 parts, high-branched polyolefin 30-40 parts, modified ethylene-vinyl alcohol copolymer 6-10 parts, modified nano zinc oxide 5-7 parts, auxiliary agent 2-3 parts, azodicarbonamide 3-5 parts, antioxidant 1010 0.4-0.8 parts, zinc stearate 1-2 parts for later use; S2, weighing the α-olefin ethylene copolymer and the modified ethylene-vinyl alcohol copolymer, adding them into an internal mixer, mixing them at 150-170° C. for 10-12 min, with the rotating speed of the internal mixer being 40-60 r / min, and obtaining a blend for use; S3, dividing the weighed modified nano zinc oxide into two parts, modified nano zinc oxide I and modified nano zinc oxide II, the mass ratio of modified nano zinc oxide I to modified nano zinc oxide II is 8:2, adding the obtained blend, high-branched polyolefin, modified nano zinc oxide I, and additives into a twin-screw extruder for extrusion granulation to obtain a masterbatch; S4, premixing the masterbatch with azodicarbonamide, antioxidant 1010, stearic acid, and modified nano zinc oxide II to obtain a mixture, injecting the mixture into a supercritical device, introducing CO2 to a pressure of 20 to 30 MPa, raising the temperature to 90 to 110° C., and treating at a constant temperature and pressure for 30 to 40 minutes, then releasing the pressure in stages to form a closed-cell foam with a gradient distribution of cell density; S5, placing the closed-cell foam with gradient cell density distribution in a mold for hot pressing and shaping.

9. The method for preparing a fast-rebound and fatigue-resistant sole foam composite material according to claim 8, characterized in that: The temperature of the extruder in step S3 is controlled in sections when performing extrusion granulation: 160° C. in zone 1, 180° C. in zone 2, 190° C. in zone 3, and the screw speed is 200 r / min.

10. The method for preparing a fast-rebound and fatigue-resistant sole foam composite material according to claim 9, characterized in that: The specific operation of the staged pressure relief in step S4 is: firstly, the pressure is relieved to 10 MPa at a speed of 3 to 5 MPa / s, and then, the pressure is relieved to normal pressure at a speed of 2 to 3 MPa / s.

Images