A high-elasticity and wear-resistant natural rubber foam insole material and its production process

Abstract

This application discloses a highly elastic and wear-resistant natural rubber foam insole material and its production process, relating to the field of foam material technology. The material comprises rubber, polyethylene resin, core-shell structured wear-resistant particles, a crosslinking accelerator, a foaming reinforcing agent, a foaming agent, a defoamer, a plasticizer, and a white paste in a weight ratio of 80-100:8-12:2-4:2.8-4.2:8-13:4-7:0.5-1.5:3-5:10-18. The rubber is composed of natural rubber and modified rubber in a mass ratio of 8-9:2-1, and the modified rubber is a PDMS / graphene composite rubber. The core-shell structured wear-resistant particles are copolymer-coated alumina particles. This application significantly improves elasticity and wear resistance.

Description

Technical Field

[0001] This application relates to the field of foam materials technology, and in particular to a high-elasticity and wear-resistant natural rubber foam insole material and its production process. Background Technology

[0002] Rubber soles are shoe soles made of rubber, which can be categorized into natural rubber and synthetic rubber. Natural rubber soles offer excellent softness and elasticity, adapting to various sports and providing shock absorption, making them commonly used in indoor sports shoes. Synthetic rubber soles can be further subdivided based on their function. Among them, abrasion-resistant rubber, with its good abrasion resistance and toughness, is often used in tennis shoe outsoles; environmentally friendly rubber contains approximately 10 wt% recycled rubber, making it relatively environmentally friendly; air-reinforced rubber contains air and offers some shock absorption, but it is not abrasion-resistant and has limited applications; viscous rubber is flexible and slip-resistant, often used in indoor sports shoes; hard rubber is tough, slip-resistant, and abrasion-resistant, often used in multi-functional shoes and basketball shoes; carbon-reinforced rubber incorporates carbon elements into ordinary rubber, making it even tougher and more abrasion-resistant, and is commonly found in running shoes.

[0003] Chinese patent application CN104788750A discloses a high-elasticity, high-abrasion-resistant rubber shoe sole and its preparation method. The high-elasticity, high-abrasion-resistant rubber shoe sole is prepared from the following raw materials in the following weight ratios: 90-110 parts natural rubber; 8-12 parts talc powder; 2-4 parts carbon tetraiodide; 1-3 parts polyacetylene; 8-12 parts polyethylene resin; 0.5-1.5 parts defoamer; 3-5 parts plasticizer; 1-3 parts abrasion-resistant particles; and 15-25 parts white oil paste.

[0004] However, the rubber soles prepared by this high-elasticity, high-wear-resistant rubber sole and its preparation method still cannot effectively balance high elasticity and high wear resistance. As a result, when wear resistance is improved, elasticity may decrease or fail to improve in a coordinated manner, which affects the user experience and needs to be improved. Summary of the Invention

[0005] In view of this, the first objective of this application is to provide a highly elastic and wear-resistant natural rubber foam insole material to improve elasticity and wear resistance. The specific solution is as follows:

[0006] A highly elastic and wear-resistant natural rubber foam insole material comprises rubber, polyethylene resin, core-shell structured wear-resistant particles, crosslinking accelerator, foaming reinforcing agent, foaming agent, defoamer, plasticizer, and white oil paste in a weight ratio of 80-100:8-12:2-4:2.8-4.2:8-13:4-7:0.5-1.5:3-5:10-18.

[0007] The rubber is composed of natural rubber and modified rubber in a mass ratio of 8-9:2-1, and the modified rubber is a PDMS / graphene composite rubber.

[0008] The core-shell structured wear-resistant particles are copolymer-coated alumina particles.

[0009] Preferably, the preparation method of the PDMS / graphene composite rubber includes step one, mixing 85-90 parts by weight of natural rubber, 5-8 parts by weight of hydroxyl-terminated PDMS, and 0.5-1 parts by weight of nano-graphene sheets to obtain a mixture; step two, adding 0.3-0.5 parts by weight of DCP to the mixture, and controlling the temperature at 120-140℃ for grafting reaction to obtain the PDMS / graphene composite rubber.

[0010] Preferably, in step one, the nanographene sheet is a modified nanographene sheet modified with a coupling agent, and the modified nanographene sheet is obtained by adding 0.5-1 parts by weight of nanographene sheet to 50-60 parts by weight of toluene, ultrasonically dispersing it evenly to form a suspension, then adding 0.2-0.4 parts by weight of KH590 and stirring at a controlled temperature of 58-62℃ for 2-2.5 hours.

[0011] Preferably, the preparation method of the copolymer-coated alumina particles includes: Step 1, stirring alumina particles and a silane coupling agent in an ethanol aqueous solution for 20-30 min, and drying at 58-62℃ after stirring to obtain pretreated alumina particles; Step 2, mixing ethylene-vinyl acetate copolymer and butadiene-acrylonitrile copolymer at a mass ratio of 1-1.5:1-1.5 to obtain a coating material, controlling the vinyl acetate content in the ethylene-vinyl acetate copolymer to be 24-26% and the acrylonitrile content in the butadiene-acrylonitrile copolymer to be 32-34%; Step 3, adding the pretreated alumina particles into the coating material, controlling the temperature at 68-72℃, the stirring speed at 500-600 r / min, and the stirring time at 1.8-2.2 h, and then adding 10% citric acid solution until the pH reaches 6-7 to obtain the coating material; Step 4, centrifuging and drying the coating material to obtain copolymer-coated alumina particles with a water content ≤0.5%.

[0012] Preferably: In step one, 0.5-0.8 parts by weight of silane coupling agent are first added to 10-15 parts of ethanol aqueous solution and stirred to obtain a silanol solution. Then, the silanol solution is added dropwise to 90-92 parts of alumina particles that have been stirred, and the stirring temperature is controlled at 78-82℃. In step two, 0.3-0.5 parts by weight of SDBS are first added to 50-60 parts of deionized water and stirred evenly. Then, ethylene-vinyl acetate copolymer and butadiene-acrylonitrile copolymer are added. After heating to 58-62℃ for 28-32 minutes, the coating material is obtained.

[0013] Preferably: the crosslinking accelerator is a sulfur-TBBS accelerator, which is obtained by mixing 2-3 parts by weight of sulfur, 0.8-1.2 parts by weight of N-tert-butyl-2-benzothiazole sulfenamide, and 0.5-0.8 parts by weight of zinc oxide; the foaming reinforcing agent is nano-calcium carbonate / OMMT material, which is obtained by mixing 6-10 parts by weight of nano-calcium carbonate and 2-3 parts by weight of organomontmorillonite; the foaming agent is obtained by mixing 3-5 parts by weight of azodicarbonamide and 1-2 parts by weight of zinc stearate; and the plasticizer is obtained by mixing dioctyl phthalate and epoxidized soybean oil in a weight ratio of 2:1.

[0014] Preferably, it further includes an additive in a weight ratio of 80-100:3.8-5.7 to the rubber, wherein the additive includes 1.8-2.7 parts by weight of an anti-aging agent and 2-3 parts by weight of an anti-slip agent, wherein the anti-aging agent is obtained by mixing TMQ and 4010NA in a mass ratio of 1-1.5:0.8-1.2; and the anti-slip agent is a CPE anti-slip agent.

[0015] The second objective of this invention is to provide a manufacturing process for highly elastic and wear-resistant natural rubber foam insoles, comprising the following steps:

[0016] Step 1: Mix rubber, polyethylene resin, core-shell structured wear-resistant particles, crosslinking accelerator, foaming reinforcing agent, foaming agent, defoamer, plasticizer, and white paste in a weight ratio of 80-100:8-12:2-4:2.8-4.2:8-13:4-7:0.5-1.5:3-5:10-18 until homogeneous to obtain a mixture.

[0017] Step 2: Add the mixture to the internal mixer, control the temperature at 90-110℃, and mix for 8-10 minutes to obtain the internally mixed mixture;

[0018] Step 3: Pour the intensively mixed mixture into the open mill, flask it out, and place it in a cold storage for 15-20 hours to obtain the cooled material;

[0019] Step 4: The cooled material is fed into the open mill, and sulfur is added to form flakes to obtain the finished foamed insole.

[0020] Preferably, it further includes an additive in a weight ratio of 80-100:3.8-5.7 to the rubber, wherein the additive includes 1.8-2.7 parts by weight of an anti-aging agent and 2-3 parts by weight of an anti-slip agent.

[0021] Preferably, the anti-aging agent is obtained by mixing TMQ and 4010NA in a mass ratio of 1-1.5:0.8-1.2; the anti-slip agent is a CPE anti-slip agent.

[0022] As can be seen from the above solutions, this application provides a highly elastic and wear-resistant natural rubber foam insole material and its manufacturing process. This highly elastic and wear-resistant natural rubber foam insole material and its manufacturing process have the following beneficial effects:

[0023] 1. By using PDMS / graphene composite rubber, a rigid main chain of natural rubber and a flexible side chain structure of PDMS are formed, which effectively reduces the internal friction between molecular chains, thereby effectively improving the elastic recovery rate. The improved fluidity also reduces the risk of cell rupture during foaming, thus forming a uniform closed-cell structure to effectively improve the elastic cushioning performance.

[0024] 2. By using PDMS / graphene composite rubber, graphene is uniformly dispersed in the natural rubber groups and forms a wear-resistant skeleton. When the highly elastic and wear-resistant natural rubber foam insole material rubs against the ground, the graphene layer consumes frictional energy through interlayer sliding, while preventing the natural rubber molecular chains from breaking and wearing away.

[0025] 3. By using the flexibility of ethylene-vinyl acetate copolymer to buffer frictional impact, and the polar nitrile groups of butadiene-acrylonitrile copolymer to work synergistically with the silane coupling agent on the alumina surface, the interface stability is significantly improved while effectively reducing the wear volume.

[0026] 4. By synergistically forming a uniform closed-cell structure with azodicarbonamide and zinc stearate, the nano-calcium carbonate / OMMT material, which acts as a foaming reinforcing agent, is further combined to achieve the effect of stabilizing the foam cells, thereby improving the impact absorption rate and effectively buffering the impact force.

[0027] 5. By mixing and compounding TMQ with 4010NA to form an anti-aging agent, it can effectively capture free radicals of thermal oxidative aging, block the reaction between ozone and rubber double bonds, and improve tensile strength; and the CPE anti-slip agent increases the hydrophilicity of the sole surface through polar chlorine atoms, which can form a water film adsorption layer on wet and slippery surfaces, thereby effectively improving anti-slip performance and safety. Detailed Implementation

[0028] The technical solutions described below in conjunction with the embodiments of this application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0029] It should be noted that the alumina particles in this application embodiment have a particle size of 5-10 μm; the nano-calcium carbonate is stearic acid-modified nano-calcium carbonate; the organo-montmorillonite is hexadecyltrimethylammonium bromide-modified organo-montmorillonite; and the chlorine content in the CPE anti-slip agent is 35-40%. The vinyl acetate content in the ethylene-vinyl acetate copolymer is 24-26%, and the acrylonitrile content in the butadiene-acrylonitrile copolymer is 32-34%. All of the above materials are commercially available and will not be described in detail here. In this application embodiment, PDMS is hydroxyl-terminated polydimethylsiloxane; DCP is dicumyl peroxide; SDBS is sodium dodecylbenzenesulfonate; OMMT is organo-montmorillonite; TMQ is 2,2,4-trimethyl-1,2-dihydroquinoline polymer antioxidant; 4010NA is N-isopropyl-N'-phenyl-p-phenylenediamine anti-ozone agent; and the CPE anti-slip agent is chlorinated polyethylene.

[0030] The following will provide a detailed description of a high-elasticity and wear-resistant natural rubber foam insole material and its manufacturing process, as described in this application.

[0031] A highly elastic and wear-resistant natural rubber foam insole material comprises rubber, polyethylene resin, core-shell structured wear-resistant particles, crosslinking accelerator, foaming reinforcing agent, foaming agent, defoamer, plasticizer, and white oil paste in a weight ratio of 80-100:8-12:2-4:2.8-4.2:8-13:4-7:0.5-1.5:3-5:10-18. The rubber is composed of natural rubber and modified rubber in a weight ratio of 8-9:2-1, and the modified rubber is a PDMS / graphene composite rubber. The preparation method of PDMS / graphene composite rubber includes step one, mixing 85-90 parts by weight of natural rubber, 5-8 parts by weight of hydroxyl-terminated PDMS, and 0.5-1 parts by weight of nano-graphene sheets to obtain a mixture; step two, adding 0.3-0.5 parts by weight of DCP to the mixture, and controlling the temperature at 120-140℃ for grafting reaction to obtain PDMS / graphene composite rubber. To improve the dispersion effect of the nano-graphene sheets and thus enhance the elasticity of the skeleton, the nano-graphene sheets in step one are modified nano-graphene sheets modified with a coupling agent. The modified nano-graphene sheets are obtained by ultrasonically dispersing 0.5-1 parts by weight of nano-graphene sheets in 50-60 parts by weight of toluene to form a suspension, then adding 0.2-0.4 parts by weight of KH590 and stirring at 58-62℃ for 2-2.5 hours.

[0032] It should be noted that the core-shell structured wear-resistant particles in this application embodiment are copolymer-coated alumina particles. The preparation method of copolymer-coated alumina particles includes: Step 1, stirring alumina particles and a silane coupling agent in an ethanol aqueous solution for 20-30 min, and drying at 58-62℃ after stirring to obtain pretreated alumina particles; Step 2, mixing ethylene-vinyl acetate copolymer and butadiene-acrylonitrile copolymer at a mass ratio of 1-1.5:1-1.5 to obtain a coating material; Step 3, adding the pretreated alumina particles to the coating material, controlling the temperature at 68-72℃, the stirring speed at 500-600 r / min, and the stirring time at 1.8-2.2 h, and then adding 10% citric acid solution until the pH reaches 6-7 to obtain the coating material; Step 4, centrifuging and drying the coating material to obtain copolymer-coated alumina particles with a water content ≤0.5%.

[0033] Step one specifically involves:

[0034] First, 0.5-0.8 parts by weight of silane coupling agent are added to 10-15 parts of ethanol aqueous solution and stirred to obtain a silanol solution. Then, the silanol solution is added dropwise to 90-92 parts of alumina particles that have been stirred, and the stirring temperature is controlled at 78-82℃. In step two, 0.3-0.5 parts by weight of SDBS are first added to 50-60 parts of deionized water and stirred evenly. Then, ethylene-vinyl acetate copolymer and butadiene-acrylonitrile copolymer are added, and the mixture is heated to 58-62℃ for 28-32 minutes to obtain the coating material.

[0035] In the embodiments of this application, the crosslinking accelerator is a sulfur-TBBS accelerator, which is obtained by mixing 2-3 parts by weight of sulfur, 0.8-1.2 parts by weight of N-tert-butyl-2-benzothiazole sulfenamide, and 0.5-0.8 parts by weight of zinc oxide. The foaming reinforcing agent is nano-calcium carbonate / OMMT material, which is obtained by mixing 6-10 parts by weight of nano-calcium carbonate and 2-3 parts by weight of organomontmorillonite. The foaming agent is obtained by mixing 3-5 parts by weight of azodicarbonamide and 1-2 parts by weight of zinc stearate. The plasticizer is obtained by mixing dioctyl phthalate and epoxidized soybean oil in a weight ratio of 2:1.

[0036] To prevent aging, maintain long-term elasticity, and improve grip on wet surfaces, additives are also included, with a weight ratio of 80-100:3.8-5.7 to rubber. These additives include 1.8-2.7 parts by weight of an anti-aging agent and 2-3 parts by weight of an anti-slip agent. The anti-aging agent is obtained by mixing TMQ and 4010NA at a mass ratio of 1-1.5:0.8-1.2. The anti-slip agent is a CPE anti-slip agent.

[0037] A manufacturing process for a highly elastic and wear-resistant natural rubber foam insole includes the following steps:

[0038] Step 1: Mix rubber, polyethylene resin, core-shell structured wear-resistant particles, crosslinking accelerator, foaming reinforcing agent, foaming agent, defoamer, plasticizer, and white paste in a weight ratio of 80-100:8-12:2-4:2.8-4.2:8-13:4-7:0.5-1.5:3-5:10-18 until homogeneous to obtain a mixture.

[0039] Step 2: Add the mixture to the internal mixer, control the temperature at 90-110℃, and mix for 8-10 minutes to obtain the internally mixed mixture;

[0040] Step 3: Pour the intensively mixed mixture into the open mill, flask it out, and place it in a cold storage for 15-20 hours to obtain the cooled material;

[0041] Step 4: The cooled material is fed into the open mill, and sulfur is added to form flakes to obtain the finished foamed insole.

[0042] It should be noted that, in order to prevent aging, maintain long-term elasticity, and improve grip on wet and slippery surfaces, an additive is added in step one at a weight ratio of 80-100:3.8-5.7 to the rubber. This additive includes 1.8-2.7 parts by weight of an anti-aging agent and 2-3 parts by weight of an anti-slip agent. The anti-aging agent is obtained by mixing TMQ and 4010NA at a mass ratio of 1-1.5:0.8-1.2. The anti-slip agent is a CPE anti-slip agent.

[0043] Example 1

[0044] A highly elastic and wear-resistant natural rubber foam insole material comprises rubber, polyethylene resin, core-shell structured wear-resistant particles, a crosslinking accelerator, a foaming reinforcing agent, a foaming agent, a defoamer, a plasticizer, and a white paste in a weight ratio of 80:8:2:2.8:8:4:0.5:3:10. The rubber is composed of natural rubber and modified rubber in a weight ratio of 8:2, and the modified rubber is a PDMS / graphene composite rubber. The preparation method of the PDMS / graphene composite rubber includes step one, mixing 85 parts by weight of natural rubber, 5 parts by weight of hydroxyl-terminated PDMS, and 0.5 parts by weight of nano-graphene sheets to obtain a mixture; and step two, adding 0.3 parts by weight of DCP to the mixture and performing a grafting reaction at a controlled temperature of 120℃ to obtain the PDMS / graphene composite rubber. To improve the dispersion effect of the graphene nanosheets and thus enhance the elasticity of the skeleton, the graphene nanosheets in step one are modified graphene nanosheets modified with coupling agents. The modified graphene nanosheets are obtained by ultrasonically dispersing 0.5 parts by weight of graphene nanosheets into 50 parts by weight of toluene to form a suspension, then adding 0.2 parts by weight of KH590 and stirring at 58°C for 2 hours.

[0045] It should be noted that the core-shell structured wear-resistant particles in this application embodiment are copolymer-coated alumina particles. The preparation method of copolymer-coated alumina particles includes: Step 1, stirring alumina particles and a silane coupling agent in an ethanol aqueous solution for 20 min, and drying at 58°C after stirring to obtain pretreated alumina particles; Step 2, mixing ethylene-vinyl acetate copolymer and butadiene-acrylonitrile copolymer at a mass ratio of 1:1.5 to obtain a coating material; Step 3, adding the pretreated alumina particles to the coating material, controlling the temperature at 68°C, the stirring speed at 500 r / min, and the stirring time at 1.8 h, and then adding 10% citric acid solution until the pH reaches 6 to obtain the coating material; Step 4, centrifuging and drying the coating material to obtain copolymer-coated alumina particles with a water content ≤0.5%.

[0046] Step one specifically involves:

[0047] First, 0.5 parts by weight of silane coupling agent are added to 10 parts of ethanol aqueous solution and stirred to obtain a silanol solution. Then, the silanol solution is added dropwise to 90 parts of alumina particles that have been stirred, and the stirring temperature is controlled at 78°C. In step two, 0.3 parts by weight of SDBS are first added to 50 parts of deionized water and stirred evenly. Then, ethylene-vinyl acetate copolymer and butadiene-acrylonitrile copolymer are added. After heating to 58°C for 28 minutes, the coating material is obtained.

[0048] In this embodiment, the crosslinking accelerator is a sulfur-TBBS accelerator, which is obtained by mixing 2 parts by weight of sulfur, 0.8 parts by weight of N-tert-butyl-2-benzothiazole sulfenamide, and 0.5 parts by weight of zinc oxide. The foaming reinforcing agent is nano-calcium carbonate / OMMT material, which is obtained by mixing 6 parts by weight of nano-calcium carbonate and 2 parts by weight of organomontmorillonite. The foaming agent is obtained by mixing 3 parts by weight of azodicarbonamide and 1 part by weight of zinc stearate. The plasticizer is obtained by mixing dioctyl phthalate and epoxidized soybean oil in a weight ratio of 2:1.

[0049] A manufacturing process for a highly elastic and wear-resistant natural rubber foam insole includes the following steps:

[0050] Step 1: Mix rubber, polyethylene resin, core-shell structure wear-resistant particles, crosslinking accelerator, foaming reinforcing agent, foaming agent, defoamer, plasticizer, and white paste in a weight ratio of 80:8:2:2.8:8:4:0.5:3:10 until homogeneous to obtain a mixture.

[0051] Step 2: Add the mixture to the internal mixer, control the temperature at 90℃, and mix for 8 minutes to obtain the internally mixed mixture;

[0052] Step 3: Pour the intensively mixed mixture into the open mill, flask it out, and place it in a cold storage for 15 hours to obtain the cooled material.

[0053] Step 4: The cooled material is fed into the open mill, and sulfur is added to form flakes to obtain the finished foamed insole.

[0054] Example 2

[0055] A highly elastic and wear-resistant natural rubber foam insole material comprises rubber, polyethylene resin, core-shell structured wear-resistant particles, crosslinking accelerator, foaming reinforcing agent, foaming agent, defoamer, plasticizer, and white paste in a weight ratio of 90:10:3:3.5:11:5:0.9:4:14. The rubber is composed of natural rubber and modified rubber in a weight ratio of 8.5:1.5, and the modified rubber is a PDMS / graphene composite rubber. The preparation method of the PDMS / graphene composite rubber includes step one, mixing 87 parts by weight of natural rubber, 7 parts by weight of hydroxyl-terminated PDMS, and 0.7 parts by weight of nano-graphene sheets to obtain a mixture; and step two, adding 0.4 parts by weight of DCP to the mixture and performing a grafting reaction at a controlled temperature of 130℃ to obtain the PDMS / graphene composite rubber. To improve the dispersion of the graphene nanosheets and thus enhance the elasticity of the framework, the graphene nanosheets in step one are modified graphene nanosheets modified with a coupling agent. The modified graphene nanosheets are obtained by ultrasonically dispersing 0.7 parts by weight of graphene nanosheets in 55 parts by weight of toluene to form a suspension, then adding 0.3 parts by weight of KH590 and stirring at 60°C for 2.2 hours. ©

[0056] It should be noted that the core-shell structured wear-resistant particles in this application embodiment are copolymer-coated alumina particles. The preparation method of copolymer-coated alumina particles includes: Step 1, stirring alumina particles and a silane coupling agent in an ethanol aqueous solution for 25 min, and drying at 60°C after stirring to obtain pretreated alumina particles; Step 2, mixing ethylene-vinyl acetate copolymer and butadiene-acrylonitrile copolymer at a mass ratio of 1.2:1 to obtain a coating material; Step 3, adding the pretreated alumina particles to the coating material, controlling the temperature at 70°C, the stirring speed at 550 r / min, and the stirring time at 2 h, and then adding 10% citric acid solution until the pH reaches 6.5 to obtain the coating material; Step 4, centrifuging and drying the coating material to obtain copolymer-coated alumina particles with a water content ≤0.5%.

[0057] Step one specifically involves:

[0058] First, 0.7 parts by weight of silane coupling agent were added to 13 parts of ethanol aqueous solution and stirred to obtain a silanol solution. Then, the silanol solution was added dropwise to 91 parts of alumina particles that had been stirred, and the stirring temperature was controlled at 80°C. In step two, 0.4 parts by weight of SDBS were first added to 55 parts of deionized water and stirred evenly. Then, ethylene-vinyl acetate copolymer and butadiene-acrylonitrile copolymer were added, and the mixture was heated to 60°C for 30 minutes to obtain the coating material.

[0059] In this embodiment, the crosslinking accelerator is a sulfur-TBBS accelerator, which is obtained by mixing 2.5 parts by weight of sulfur, 1 part by weight of N-tert-butyl-2-benzothiazole sulfenamide, and 0.6 parts by weight of zinc oxide. The foaming reinforcing agent is nano-calcium carbonate / OMMT material, which is obtained by mixing 8 parts by weight of nano-calcium carbonate and 2.5 parts by weight of organomontmorillonite. The foaming agent is obtained by mixing 4 parts by weight of azodicarbonamide and 1.5 parts by weight of zinc stearate. The plasticizer is obtained by mixing dioctyl phthalate and epoxidized soybean oil in a weight ratio of 2:1.

[0060] A manufacturing process for a highly elastic and wear-resistant natural rubber foam insole includes the following steps:

[0061] Step 1: Mix rubber, polyethylene resin, core-shell structure wear-resistant particles, crosslinking accelerator, foaming reinforcing agent, foaming agent, defoamer, plasticizer, and white paste in a weight ratio of 90:10:3:3.5:11:5:0.9:4:14 until homogeneous to obtain a mixture.

[0062] Step 2: Add the mixture to the internal mixer, control the temperature at 100℃, and mix for 9 minutes to obtain the internally mixed mixture;

[0063] Step 3: Pour the intensively mixed mixture into the open mill, flask it out, and place it in a cold storage for 17 hours to obtain the cooled material.

[0064] Step 4: The cooled material is fed into the open mill, and sulfur is added to form flakes to obtain the finished foamed insole.

[0065] Example 3

[0066] A highly elastic and wear-resistant natural rubber foam insole material comprises rubber, polyethylene resin, core-shell structured wear-resistant particles, a crosslinking accelerator, a foaming reinforcing agent, a foaming agent, a defoamer, a plasticizer, and a white paste in a weight ratio of 100:12:4:4.2:13:7:1.5:5:18. The rubber is composed of natural rubber and modified rubber in a weight ratio of 9:1, and the modified rubber is a PDMS / graphene composite rubber. The preparation method of the PDMS / graphene composite rubber includes step one, mixing 90 parts by weight of natural rubber, 8 parts by weight of hydroxyl-terminated PDMS, and 1 part by weight of nano-graphene sheets to obtain a mixture; and step two, adding 0.5 parts by weight of DCP to the mixture and performing a grafting reaction at a controlled temperature of 140℃ to obtain the PDMS / graphene composite rubber. To improve the dispersion effect of the graphene nanosheets and thus enhance the elasticity of the skeleton, the graphene nanosheets in step one are modified graphene nanosheets modified with coupling agents. The modified graphene nanosheets are obtained by ultrasonically dispersing 1 part by weight of graphene nanosheets into 60 parts by weight of toluene to form a suspension, then adding 0.4 parts of KH590 and stirring at 62°C for 2.5 hours.

[0067] It should be noted that the core-shell structured wear-resistant particles in this application embodiment are copolymer-coated alumina particles. The preparation method of copolymer-coated alumina particles includes: Step 1, stirring alumina particles and a silane coupling agent in an ethanol aqueous solution for 30 min, and drying at 62°C after stirring to obtain pretreated alumina particles; Step 2, mixing ethylene-vinyl acetate copolymer and butadiene-acrylonitrile copolymer at a mass ratio of 1.5:1 to obtain a coating material; Step 3, adding the pretreated alumina particles to the coating material, controlling the temperature at 72°C, the stirring speed at 600 r / min, and the stirring time at 2.2 h, and then adding 10% citric acid solution until the pH reaches 7 to obtain the coating material; Step 4, centrifuging and drying the coating material to obtain copolymer-coated alumina particles with a water content ≤0.5%.

[0068] Step one specifically involves:

[0069] First, 0.8 parts by weight of silane coupling agent are added to 15 parts by weight of ethanol aqueous solution and stirred to obtain a silanol solution. Then, the silanol solution is added dropwise to 92 parts by weight of alumina particles that have been stirred, and the stirring temperature is controlled at 82°C. In step two, 0.5 parts by weight of SDBS are first added to 60 parts by weight of deionized water and stirred evenly. Then, ethylene-vinyl acetate copolymer and butadiene-acrylonitrile copolymer are added. After heating to 62°C for 32 minutes, the coating material is obtained.

[0070] In this embodiment, the crosslinking accelerator is a sulfur-TBBS accelerator, which is obtained by mixing 3 parts by weight of sulfur, 1.2 parts by weight of N-tert-butyl-2-benzothiazole sulfenamide, and 0.8 parts by weight of zinc oxide. The foaming reinforcing agent is nano-calcium carbonate / OMMT material, which is obtained by mixing 10 parts by weight of nano-calcium carbonate and 3 parts by weight of organomontmorillonite. The foaming agent is obtained by mixing 5 parts by weight of azodicarbonamide and 2 parts by weight of zinc stearate. The plasticizer is obtained by mixing dioctyl phthalate and epoxidized soybean oil in a weight ratio of 2:1.

[0071] A manufacturing process for a highly elastic and wear-resistant natural rubber foam insole includes the following steps:

[0072] Step 1: Mix rubber, polyethylene resin, core-shell structure wear-resistant particles, crosslinking accelerator, foaming reinforcing agent, foaming agent, defoamer, plasticizer, and white paste in a weight ratio of 100:12:4:4.2:13:7:1.5:5:18 until homogeneous to obtain a mixture.

[0073] Step 2: Add the mixture to the internal mixer, control the temperature at 110℃, and mix for 10 minutes to obtain the internally mixed mixture;

[0074] Step 3: Pour the intensively mixed mixture into the open mill, flask it out, and place it in a cold storage for 20 hours to obtain the cooled material;

[0075] Step 4: The cooled material is fed into the open mill, and sulfur is added to form flakes to obtain the finished foamed insole.

[0076] Example 4

[0077] The difference between Example 4 and Example 1 is that, in order to prevent aging, maintain long-term elasticity, and improve grip on wet and slippery surfaces, Example 4 also includes adding an additive to the highly elastic and wear-resistant natural rubber foam insole material at a weight ratio of 80:3.8 to the rubber. The additive includes 1.8 parts by weight of an anti-aging agent and 2 parts by weight of an anti-slip agent. The anti-aging agent is obtained by mixing TMQ and 4010NA at a mass ratio of 1:0.8. The anti-slip agent is a CPE anti-slip agent.

[0078] Example 5

[0079] The difference between Example 5 and Example 2 is that, in Example 5, to prevent aging, maintain long-term elasticity, and improve grip on wet and slippery surfaces, an additive with a weight ratio of 90:4.3 to the rubber is added to the highly elastic and wear-resistant natural rubber foam insole material. The additive includes 2.1 parts by weight of an anti-aging agent and 2.2 parts by weight of an anti-slip agent. The anti-aging agent is obtained by mixing TMQ and 4010NA at a mass ratio of 6:5. The anti-slip agent is a CPE anti-slip agent.

[0080] Example 6

[0081] The difference between Example 6 and Example 3 is that, in Example 6, to prevent aging, maintain long-term elasticity, and improve grip on wet surfaces, an additive with a weight ratio of 100:5.7 to the rubber is added to the highly elastic and wear-resistant natural rubber foam insole material. The additive includes 2.7 parts by weight of an anti-aging agent and 3 parts by weight of an anti-slip agent. The anti-aging agent is obtained by mixing TMQ and 4010NA in a mass ratio of 5:4. The anti-slip agent is a CPE anti-slip agent.

[0082] Comparative Example 1

[0083] The difference between Comparative Example 1 and Example 2 is that the modified rubber in Comparative Example 1 did not have terminal hydroxyl PDMS added.

[0084] Comparative Example 2

[0085] The difference between Comparative Example 2 and Example 2 is that the modified rubber in Comparative Example 2 did not contain graphene nanosheets.

[0086] Comparative Example 3

[0087] The difference between Comparative Example 3 and Example 2 is that the core-shell structure wear-resistant particles in Comparative Example 3 are nano-alumina coated with sodium dodecyl sulfate, and the thickness is the same as that in Comparative Example 2, which is 0.7 μm.

[0088] Performance testing:

[0089] 1. Compression set: According to GB / T 7759.1-2015 "Determination of compression set of vulcanized rubber or thermoplastic rubber";

[0090] 2. Elastic recovery rate: According to GB / T 1685.1-2008 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber";

[0091] 3. Abrasion resistance: According to GB / T 9867-2008 "Determination of abrasion resistance of vulcanized rubber or thermoplastic rubber".

[0092] The performance test results are shown in Table 1 below.

[0093] Table 1 Performance Test Results

[0094]

[0095] As shown in Table 1 above, Example 1 of this application contains 20% PDMS / graphene composite rubber in the modified rubber, and the foaming reinforcing agent consists of 6 parts nano-calcium carbonate and 2 parts OMMT to stabilize the cells. However, the amount of PDMS and graphene is lower compared to Examples 2 and 3, resulting in lower elasticity. Furthermore, Comparative Example 1 of this application, due to the absence of PDMS in the modified rubber, suffers from insufficient molecular chain flexibility and easy cell collapse, leading to a significant increase in compression set and a decrease in elastic recovery rate to the level of pure natural rubber. Comparative Example 2 of this application, due to the absence of graphene, lacks nanostructure support, causing easy deformation of the cell walls.

[0096] Based on Comparative Example 3 and Example 3, since the core particles are coated with SDS, the physical adsorption method will cause the coating layer to fall off easily during wear. Furthermore, the exposed alumina particles scratch the rubber matrix, resulting in a significantly higher wear volume than the comparative example.

[0097] In Examples 4 to 6, the addition of anti-slip agents and anti-aging agents improves the anti-slip and anti-aging effects, but has little impact on the overall strength and elasticity.

[0098] In summary, this application provides a highly elastic and wear-resistant natural rubber foam insole material and its manufacturing process. This material and process utilizes a PDMS / graphene composite rubber to form a rigid natural rubber main chain and a flexible PDMS side chain structure, effectively reducing internal friction between molecular chains and thus significantly improving elastic recovery. Furthermore, the improved flowability reduces the risk of cell rupture during foaming, resulting in a uniform closed-cell structure that effectively enhances elastic cushioning performance. Simultaneously, the PDMS / graphene composite rubber ensures that graphene is uniformly dispersed within the natural rubber groups, forming a wear-resistant skeleton. This allows the graphene layer to dissipate frictional energy through interlayer sliding when the material rubs against the ground, while simultaneously preventing the breakage and wear of the natural rubber molecular chains. In the copolymer-coated alumina particles, the flexibility of the ethylene-vinyl acetate copolymer buffers frictional impact, and the polar nitrile groups of the butadiene-acrylonitrile copolymer synergistically work with the silane coupling agent on the alumina surface, significantly improving interfacial stability while effectively reducing wear volume. Meanwhile, in this highly elastic and wear-resistant natural rubber foam insole material, azodicarbonamide and zinc stearate synergistically form a uniform closed-cell structure, further combining with nano-calcium carbonate / OMMT material as a foaming reinforcement to achieve cell stability, thereby improving impact absorption and effectively cushioning impact. Furthermore, by mixing and compounding TMQ and 4010NA to form an anti-aging agent, it effectively captures thermo-oxidative aging free radicals, blocks the reaction between ozone and rubber double bonds, and improves tensile strength. Additionally, the CPE anti-slip agent increases the hydrophilicity of the sole surface through polar chlorine atoms, forming a water film adsorption layer on wet and slippery surfaces, thus effectively improving anti-slip performance and safety.

[0099] The terms “first,” “second,” “third,” “fourth,” etc., used in this application (if applicable) are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, or apparatus that includes a series of steps or units is not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, or apparatus.

[0100] It should be noted that the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of those features. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0101] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A highly elastic and wear-resistant natural rubber foam insole material, characterized in that, Including rubber, polyethylene resin, core-shell structured wear-resistant particles, crosslinking accelerators, foaming reinforcing agents, foaming agents, defoamers, plasticizers, and white paste in a weight ratio of 80-100:8-12:2-4:2.8-4.2:8-13:4-7:0.5-1.5:3-5:10-18; The rubber is composed of natural rubber and modified rubber in a mass ratio of 8-9:2-1, and the modified rubber is a PDMS / graphene composite rubber. The preparation method of the PDMS / graphene composite rubber includes: Step 1, mixing 85-90 parts by weight of natural rubber, 5-8 parts by weight of hydroxyl-terminated PDMS, and 0.5-1 parts by weight of nano-graphene sheets to obtain a mixture; Step 2, adding 0.3-0.5 parts by weight of DCP to the mixture, and controlling the temperature at 120-140℃ for grafting reaction to obtain PDMS / graphene composite rubber; and in Step 1, the nano-graphene sheets are modified nano-graphene sheets modified with coupling agents, and the modified nano-graphene sheets are obtained by adding 0.5-1 parts by weight of nano-graphene sheets to 50-60 parts by weight of toluene, ultrasonically dispersing them evenly to form a suspension, then adding 0.2-0.4 parts by weight of KH590 and stirring at 58-62℃ for 2-2.5 hours. The core-shell structured wear-resistant particles are copolymer-coated alumina particles. The preparation method of the copolymer-coated alumina particles includes: Step 1, stirring alumina particles and a silane coupling agent in an ethanol-water solution for 20-30 minutes, and then drying at 58-62℃ after stirring to obtain pretreated alumina particles; Step 2, mixing ethylene-vinyl acetate copolymer and butadiene-acrylonitrile copolymer at a mass ratio of 1-1.5:1-1.5 to obtain the coating material, controlling the vinyl acetate content in the ethylene-vinyl acetate copolymer... The vinyl acetate content is 24-26%, and the acrylonitrile content in the butadiene-acrylonitrile copolymer is 32-34%; in step three, the pretreated alumina particles are added to the coating material, the temperature is controlled at 68-72℃, the stirring speed is 500-600r / min, and the stirring time is 1.8-2.2h, and then 10% citric acid solution is added dropwise until the pH reaches 6-7 to obtain the coating material; in step four, the coating material is centrifuged and dried to obtain copolymer-coated alumina particles with a water content ≤0.5%.

2. The high-elasticity and wear-resistant natural rubber foam insole material according to claim 1, characterized in that: In step one, 0.5-0.8 parts by weight of silane coupling agent are first added to 10-15 parts of ethanol aqueous solution and stirred to obtain a silanol solution. The silanol solution is then added dropwise to 90-92 parts of alumina particles that have been stirred, and the stirring temperature is controlled at 78-82℃. In step two, 0.3-0.5 parts by weight of SDBS are first added to 50-60 parts of deionized water and stirred evenly. Then, ethylene-vinyl acetate copolymer and butadiene-acrylonitrile copolymer are added, and the mixture is heated to 58-62℃ for 28-32 minutes to obtain the coating material.

3. The highly elastic and wear-resistant natural rubber foam insole material according to claim 1, characterized in that: The crosslinking accelerator is a sulfur-TBBS accelerator, which is obtained by mixing 2-3 parts by weight of sulfur, 0.8-1.2 parts by weight of N-tert-butyl-2-benzothiazole sulfenamide, and 0.5-0.8 parts by weight of zinc oxide; the foaming reinforcing agent is nano-calcium carbonate / OMMT material, which is obtained by mixing 6-10 parts by weight of nano-calcium carbonate and 2-3 parts by weight of organomontmorillonite; the foaming agent is obtained by mixing 3-5 parts by weight of azodicarbonamide and 1-2 parts by weight of zinc stearate; the plasticizer is obtained by mixing dioctyl phthalate and epoxidized soybean oil in a weight ratio of 2:

1.

4. The highly elastic and wear-resistant natural rubber foam insole material according to claim 1, characterized in that: It also includes additives in a weight ratio of 80-100:3.8-5.7 with rubber, the additives including 1.8-2.7 parts by weight of an anti-aging agent and 2-3 parts by weight of an anti-slip agent, the anti-aging agent being obtained by mixing TMQ and 4010NA in a mass ratio of 1-1.5:0.8-1.2; the anti-slip agent being a CPE anti-slip agent.

5. A production process for a highly elastic and wear-resistant natural rubber foam insole, applied to the highly elastic and wear-resistant natural rubber foam insole material as described in any one of claims 1-4, characterized in that: Includes the following steps: Step 1: Mix rubber, polyethylene resin, core-shell structured wear-resistant particles, crosslinking accelerator, foaming reinforcing agent, foaming agent, defoamer, plasticizer, and white paste in a weight ratio of 80-100:8-12:2-4:2.8-4.2:8-13:4-7:0.5-1.5:3-5:10-18 until homogeneous to obtain a mixture. Step 2: Add the mixture to the internal mixer, control the temperature at 90-110℃, and mix for 8-10 minutes to obtain the internally mixed mixture; Step 3: Pour the intensively mixed mixture into the open mill, flask it out, and place it in a cold storage for 15-20 hours to obtain the cooled material; Step 4: The cooled material is fed into the open mill, and sulfur is added to form flakes to obtain the finished foamed insole.

6. The production process of a high-elasticity and wear-resistant natural rubber foam insole according to claim 5, characterized in that: It also includes additives in a weight ratio of 80-100:3.8-5.7 to rubber, wherein the additives include 1.8-2.7 parts by weight of an anti-aging agent and 2-3 parts by weight of an anti-slip agent.

7. The production process of a high-elasticity and wear-resistant natural rubber foam insole according to claim 6, characterized in that: The anti-aging agent is obtained by mixing TMQ and 4010NA in a mass ratio of 1-1.5:0.8-1.2; the anti-slip agent is CPE anti-slip agent.

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