Air pressure supporting EVA chemical foaming sole material and preparation method thereof

Abstract

The application discloses a kind of EVA chemical foaming shoe sole material of air pressure support and preparation method thereof, starting from EVA chemical foaming secondary mould pressing process, by the improvement of process, utilize temperature regulation to improve melt strength, simultaneously by substantially increasing the dosage of foaming agent, make its balance time base strength and gas pressure match, to improve gas pressure, strengthen the gas in the inside of shoe sole, the prepared foaming material has ultra-light (density 0.10±0.02), ultra-elastic (rebound rate is as high as 78%), simultaneously its low hardness compression modulus is higher, soft and not collapse, guarantee its static soft comfort and dynamic support stability.The shoe sole physical property of the application can be comparable with supercritical physical foaming material, and the foaming process is greatly simplified compared with supercritical physical foaming.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of composite foaming shoe sole materials, and particularly relates to an EVA chemical foaming shoe sole material with air pressure support and a preparation method thereof. BACKGROUND

[0002] Inflatable materials are a kind of materials composed of sealing gas in the material, which can realize spring action through high-pressure gas compression-release, and the action is widely used in cushioning, rebound support and other aspects (such as tires, air springs, air cushion shoes, basketballs, etc.). EVA foaming materials are a kind of closed-cell and microcellular foaming materials, and the essence is also a kind of inflatable material sealing gas in the material, which can also realize its functionality through the compression-release of gas.

[0003] The traditional EVA foaming process mainly utilizes chemical foaming agent (azodicarbonamide) to decompose to produce gas at high temperature, and the decomposition of peroxide produces free radicals to crosslink the EVA matrix material. When the mold is opened, the EVA matrix expands to complete foaming, and the crosslinking action makes the pore wall have enough strength to lock the gas. When the mold is opened, the pores grow, and the pores remain stable. At the same time, the crosslinked EVA foaming material obtains a certain strength, so that it can be used within a certain temperature range. From the temperature effect on the pores, the foaming temperature is mostly 170-180℃, that is, the mold opening expansion temperature is 170-180℃. According to PV=nRT, the gas pressure is high at this time, and the strength of the material is low at high temperature. The high-pressure gas is easy to expand. When the temperature drops to room temperature, the gas pressure will be greatly reduced due to the increase in pore volume and the decrease in temperature, and the support of the air pressure is lost. At this time, the foaming shoe sole provides a large amount of support by the hardness of the material. Generally, a large expansion ratio will result in low hardness, and a light shoe sole will select a high-hardness raw material. The rebound resilience of EVA, POE and other raw materials will decrease with the increase of hardness, so the traditional EVA foaming light shoe sole and its manufacturing process are difficult to balance the hardness support and high rebound performance of the shoe sole.

[0004] The material properties of the EVA foaming shoe sole can be realized by adjusting the internal gas pressure in addition to the material properties of the matrix material. The spring effect can be realized by using high-pressure gas compression-release. According to PV=nRT, under the same temperature and volume, increasing the gas can increase the gas pressure. In the actual EVA foaming operation, the gas pressure can be increased by increasing the amount of foaming agent under the condition of ensuring the same ratio. In the conventional EVA secondary molding operation, the amount of foaming agent can be increased by increasing the crosslinking density or using an elastomer with a larger Mooney viscosity, but the increase is limited. Moreover, the material processing fluidity of this method is poor, which can easily cause shoe sole production defects. The strength of the gas core wall is increased by mold cooling, the high-pressure gas is not easy to expand in an instant, the integrity of the pores can be maintained, and the material fluidity can be ensured by avoiding increasing the pore strength by increasing the crosslinking density, so the range of elastomer raw materials is larger, and the proportion of the elastomer in the formula can be larger. SUMMARY

[0005] Therefore, the application discloses a gas pressure supported EVA chemical foaming shoe sole material and a preparation method thereof. The EVA chemical foaming secondary molding process is improved by using temperature regulation to increase the melt strength, and by greatly increasing the amount of foaming agent, so that the matrix strength and the gas pressure are matched at the same time, thereby increasing the gas pressure and enhancing the gas in the shoe sole. The prepared foaming material has ultra-light (density 0.10±0.02), ultra-elastic (rebound rate up to 78%), and high compression modulus at low hardness, soft and not collapsed, which ensures the static softness and dynamic support stability, and can be comparable to high-performance supercritical physical foaming materials.

[0006] The application provides a gas pressure supported EVA chemical foaming shoe sole material, which comprises the following components in mass parts:

[0007] 100 parts of EVA composite elastomer material; 5-10 parts of gas barrier rubber; 0.25-0.6 parts of crosslinking agent; 6-10 parts of foaming agent; 0.25-0.5 parts of stearic acid; 0.8-1.2 parts of zinc stearate; 1.2-2.5 parts of zinc oxide; and 3-5 parts of filler.

[0008] Preferably, the EVA composite elastomer material is 40-60 parts of EVA; 40-60 parts of polyolefin elastomer; and 0-20 parts of a new high-performance elastomer; wherein the VA content in the EVA is 26%-40%; the polyolefin elastomer comprises one or more of POE, OBCs, EPDM and SEBS; and the new high-performance elastomer comprises one or more of thermoplastic polyurethane elastomer (TPU), polyester elastomer (TPEE) and nylon elastomer (PEBA).

[0009] Preferably, the gas barrier rubber is butyl rubber or halogenated butyl rubber with outstanding air tightness.

[0010] Preferably, the cross-linking agent BIBP (1,4-bis-tert-butyl peroxy isopropyl benzene)

[0011] Preferably, the foaming agent is one or more of azodicarbonamide and modified foaming agent H.

[0012] Preferably, the filler is one or more of talc and calcium carbonate.

[0013] The present application provides a preparation method of air pressure supporting EVA chemical foaming shoe sole, and the specific steps are as follows:

[0014] Step 1: weigh each composition according to the above defined proportion, then mix all components except cross-linking agent and foaming agent, and then add the weighed cross-linking agent and foaming agent to the blended material and continue mixing, finally granulate the uniformly mixed mixture, and place the prepared particles for cooling.

[0015] Step 2: according to the mold type, weigh a certain mass of particles in step 1 and pour into the mold cavity, then after closing the mold, transfer the mold into the hot pressing hole, automatically hook the mold, and perform hot pressing foaming for a certain time.

[0016] Step 3: transfer the mold into the water cooling hole, and after cooling for a certain time, open the mold to take out the inflated cold embryo.

[0017] Step 4: place the inflated cold embryo in step 3 in a transmission oven for temperature rising foaming to obtain a secondary molded small foam.

[0018] Step 5: perform secondary molding on the molded small foam in step 3 to obtain an air pressure supporting EVA chemical foaming shoe sole material.

[0019] Preferably, the temperature of the internal mixer in step 1 is controlled at 120-125℃, and the time for continued mixing after adding the cross-linking agent and foaming agent is 3-5 min.

[0020] Preferably, the automatic hooking of the mold in step 2 is four side hooks to increase the mold sealing property and locking force; the hot pressing foaming is hot pressing plate temperature 170-180℃, and hot pressing time 600-800s.

[0021] Preferably, the water cooling time in step 3 is 500-600s.

[0022] Preferably, the transmission oven parameters in step 4 are set as follows: temperature: 90℃ for the first section, 80℃ for the second section, 70℃ for the third section, and 60℃ for the fourth section; baking time: 30-40 min for the whole process.

[0023] Preferably, the secondary molding of step 5 is provided with a hot pressing time of 420-480s, a water cooling time of 450-550s, and a hot pressing temperature of 170-175℃.

[0024] Compared with the prior art, the EVA chemical foaming sole material with air pressure support provided by the application has the following beneficial effects: the improved secondary molding process is used in the EVA chemical foaming sole material with air pressure support, the method of physical foaming and temperature foaming is used for reference, the air-filled cold blank is prepared first, and then the out-of-mold foaming is performed at a suitable temperature; the amount of foaming agent is increased by means of temperature control; the conventional EVA chemical foaming sole formula is used as the main formula; the gas barrier rubber is introduced; the air pressure of the material is improved while the air tightness is ensured; the prepared sole foaming material achieves the purpose of strengthening from the perspective of air and is not limited to the selection of the formula base material; the super-light, super-elastic, soft and non-collapsing insole material can be developed; the static softness and dynamic support stability of sports shoes are ensured; the physical properties of the sole can be comparable to those of the supercritical physical foaming material; and the foaming process is greatly simplified compared with the supercritical physical foaming process. Embodiment

[0025] The technical solutions in the embodiments of the application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0026] The application provides an EVA chemical foaming sole material with air pressure support, which comprises the following components in mass parts:

[0027] 100 parts of EVA composite elastomer material; 5-10 parts of gas barrier rubber; 0.25-0.6 parts of crosslinking agent; 6-10 parts of foaming agent; 0.25-0.5 parts of stearic acid; 0.8-1.2 parts of zinc stearate; 1.2-2.5 parts of zinc oxide; and 3-5 parts of filler.

[0028] The EVA foaming sole material provided in the application improves the performance of the foaming material from the perspective of enhancing the air pressure, prepares the foaming insole material with super-lightness, super-elasticity, softness and non-collapse, ensures the static softness and dynamic support stability of sports shoes, and can be comparable to high-performance physical foaming materials, and is used for high-performance training or racing shoes.

[0029] The above material of the present application comprises 100 parts of EVA composite elastomer, wherein the EVA composite elastomer refers to a conventional formula with EVA as the main material, composite polyolefin elastomer and new high-performance elastomer, wherein the polyolefin elastomer comprises one or more of POE, OBCs, EPDM, SEBS and their blended modified materials; the new high-performance elastomer comprises one or more of thermoplastic polyurethane elastomer (TPU), polyester elastomer (TPEE) and nylon elastomer (PEBA). When the high-performance elastomer is introduced into the formula, melt blending is first carried out by using a double screw.

[0030] As preferred, the EVA composite elastomer of the present application has the following proportions by mass: 40-60 parts of EVA; 40-60 parts of polyolefin elastomer; and 0-20 parts of new high-performance elastomer. Specifically, the VA mass content in the EVA of the present application can be 26%-40%, and the EVA with such VA content has high molecular chain flexibility, which ensures the softness and high resilience of the composite material. As preferred, the type can be one or more of EVA 7470M, EVA V33121, EVA 40W and EVA 40L-03. Specifically, the polyolefin elastomer of the present application is a commonly used elastomer for EVA composite modification, which has low crystallinity and good molecular chain flexibility, ensuring its high resilience performance, but has low hardness and small elastic modulus. As preferred, the type can be POE: Engage 8180, Engage 7467, Engage 8150 and ENGAGE 8003; OBCs: Infuse 9107 and Infuse 9507; and EPDM and SEBS blended modified materials: NORDEL IP 3745P and EPT 3092M. Specifically, the new high-performance elastomer of the present application refers to a kind of elastomer having the resilience of rubber and the strength of engineering plastic, which is widely used for physical foaming and has excellent resilience and support stability. The raw materials thereof are thermoplastic polyurethane elastomer (TPU), polyester elastomer (TPEE) and nylon elastomer (PEBA), which have high melting temperature and softening point. When the new high-performance elastomer is compounded in the EVA formula, the dimensional stability and resilience performance of the foaming material can be improved. However, due to the low melt strength of the new high-performance elastomer at high temperature and the high acidity thereof, the crosslinking of peroxide in the system is greatly affected, so that the foaming is poor when the new high-performance elastomer is introduced into the formula in a high proportion. As preferred, the component in the formula is not more than 20 parts, and the type can be TPU: Elastollan 1190A; TPEE: Hytrel®4056, G-4065D and H-4865D; and PEBA: VESTAMIDE 40-S3 and Pebax 4033. The present application can ensure the comprehensive performance of the composite foaming material by reasonable formula matching.

[0031] The above material of the present application comprises 5-10 parts of a gas barrier rubber, which is butyl rubber or halogenated butyl rubber. Butyl rubber is a copolymer of butene and a small amount of isoprene, and the isobutene main chain is its main component. The symmetric methyl groups on both sides of the main chain cause steric hindrance, which makes the rubber molecular chain move slowly, and it is difficult for gas molecules to pass through, thereby achieving the effect of increasing the gas tightness. Therefore, butyl rubber has excellent gas tightness, but its molecular chain flexibility is poor, and its rebound performance is poor. By introducing a reasonable component of butyl rubber into the EVA formula, the gas tightness of the composite foamed material can be improved to achieve the purpose of pressure retention, while ensuring its high rebound performance. In the examples of the present application, as a preferred, the selected butyl rubber model is BIIR X2, and the Mooney viscosity is 46 [ML (1+8) 125℃].

[0032] The above material of the present application comprises 6-10 parts of a foaming agent, which is one or more of azodicarbonamide and modified foaming agent H. Azodicarbonamide as a foaming agent, foaming is rapid and stable, and the gas generation amount is large without residue. Specifically, as an example of the present application, the selected azodicarbonamide foaming agent has a small particle size and a narrow distribution, and the particle size range is 5-10 μm. The fine particle size makes the foaming agent more uniformly distributed in the composite base material, which can ensure that more gas nuclei are formed during foaming, the cell size is small, and the cell density is large. The narrow distribution can ensure the uniformity of the pores. Foaming agent H is N,N-diazidopentamethylene tetramine, which has a large decomposition gas volume, and the amount of ammonia in the decomposition product is relatively large compared with other foaming agents. However, its decomposition temperature is relatively high, and the addition of urea as a foaming aid can reduce the decomposition temperature to below 140℃. For some EVA composite bases with relatively strong acidity (such as the introduction of thermoplastic polyurethane elastomer (TPU), polyester elastomer (TPEE), and nylon elastomer (PEBA) in the formula, which usually have relatively high acidity), the acid performance of the base affects the decomposition of the bridging agent peroxide radical and the crosslinking reaction of the system. By adding the modified foaming agent H, the ammonia produced by the decomposition of the modified foaming agent H can adjust the acidity of the system before the decomposition of the peroxide bridging agent, so that the system can foam normally and achieve the purpose of introducing high-performance elastomers. In the examples of the present application, as a preferred, the foaming agent model is: azodicarbonamide is AC6000, AC7000; modified foaming agent H is S12.

[0033] According to PV=nRT, under the same temperature and volume, increasing the gas can increase the gas pressure. In actual EVA foaming operation, increasing the amount of foaming agent can increase the gas pressure under the same ratio. However, with the increase of the foaming agent, the gas pressure is enhanced, and when the cell wall strength cannot constrain the gas, it will cause the pores to be broken, which will cause the performance of the foamed material to be reduced. In the examples of the present application, the amount of foaming agent is 6-10 parts, preferably 7-8 parts.

[0034] The above material of the application comprises 3-5 parts of a filler, also known as a filler, an additive, a filler, which can improve the material performance and reduce the cost. In the application, the filler is preferably selected from one or more of talc, calcium carbonate, and more preferably talc. In the preferred embodiment of the application, the filler used is a uniform fine particle with a particle size of less than 6 μm, which can be well distributed in the entire composite material system, and can play the role of heterogeneous nucleation, making the foaming cells more uniform.

[0035] The stearic acid, zinc stearate and zinc oxide in the above material of the application are conventional foaming aids, and no specific requirements are made, and they can be purchased on the market.

[0036] Correspondingly, the application provides a preparation method of the air pressure supported EVA chemical foaming shoe sole, comprising the following steps:

[0037] Step 1: weigh each component according to the above defined proportion, then mix all components except crosslinking agent and foaming agent, then add the weighed crosslinking agent and foaming agent during the mixing of the blended material, and finally granulate the uniformly mixed mixture, and place the prepared particles for cooling.

[0038] Step 2: according to the mold type, weigh a certain amount of particles in step 1 and pour them into the mold cavity, then transfer the mold into the hot pressing hole after closing the mold, automatically hook the mold, and perform hot pressing foaming.

[0039] Step 3: transfer the mold into the water cooling hole, and after cooling for a certain time, open the mold to take out the inflated cold embryo.

[0040] Step 4: inflate the cold embryo in step 3 in the transmission oven to perform temperature foaming, and obtain a secondary molding small foaming.

[0041] Step 5: perform secondary molding of the molded small foaming in step 4 to obtain an air pressure supported EVA chemical foaming shoe sole material.

[0042] The preparation method of the application uses the processing method of the traditional secondary MD foaming shoe sole material, learns from the supercritical physical foaming temperature foaming idea, and controls the temperature to increase the gas amount and use the low temperature foaming of the temperature control means to perform foaming, improve the cell strength, balance the gas pressure and the cell strength, and thus enhance the gas pressure of the foaming material.

[0043] In step 1 of the application, all components except crosslinking agent and foaming agent are mixed, the mixing temperature is controlled at 120-125℃, and after adding the crosslinking agent and foaming agent, the mixing time is 3-5 min. The mixing temperature ensures the uniform mixing of the materials, and the continuous mixing time ensures the uniform mixing of the bridging agent without decomposition to cause dead material;

[0044] The automatic hook locking in step 2 of the application is a conventional component of the MD secondary foaming forming mold, the conventional single-sided hook is improved to a four-sided hook to increase the mold clamping sealing property and the locking force, and the material in the mold cavity can be limited from overflowing due to the strong inflation gas pressure, thereby preventing defects such as blowout; the hot-pressing foaming is performed at a hot-pressing plate temperature of 170-180℃ and a hot-pressing time of 600-800s.

[0045] After the water cooling for a certain time in step 3 of the application, the mold is opened to take out the inflated cold blank, wherein the water cooling time is 500-600s, the inflated cold blank is a micro-foaming cold blank with a foaming ratio of 1.05-1.2 (inflated cold blank ratio line length / mold ratio line length), and gas nuclei have been formed in the cold blank, the gas pressure is relatively low at low temperature, the chain segments of the matrix material are not easy to move at a temperature far below the softening point, and the matrix strength is high, thereby limiting the growth and expansion of the pores.

[0046] The inflated cold blank in step 4 of the application is subjected to temperature foaming in a transmission oven to obtain a secondary formed small foam, wherein the temperature foaming is performed in the transmission oven, the transmission oven parameters are set as follows: temperature: 90℃ for the first section, 80℃ for the second section, 70℃ for the third section, and 60℃ for the fourth section; baking time: 30-40min for the whole process, controlled by the transmission speed; and the secondary formed small foam ratio is 1.9-2.1. When the oven is heated, the gas pressure increases with the increase of the temperature, and the chain segment activity of the matrix molecule chain increases. In order to balance the gas pressure and the pore strength, the pores grow and expand to complete the foaming, and the foaming material at this temperature is ensured to be completely foamed during the shoe material fitting process, and the material will not be inflated again to cause defects during the irradiation in the fitting process.

[0047] Compared with the conventional foaming (mold opening temperature 170-180℃), the pore strength is high at a low temperature (70-90℃), the pressure drop caused by the temperature has little effect on the pore deformation when the gas pressure and the pore strength are balanced, the effect of the pressure drop caused by the temperature on the increase of the pore volume is small, and the gas pressure itself increases due to the pore strength, thereby achieving the pressure enhancement. From the appearance, compared with the conventional foaming agent dosage (3-6 parts) at the same ratio (ratio 2.0), the foaming agent dosage of the application is large (6-10 parts), and according to PV=nRT, the gas pressure in the small foaming material is high.

[0048] Step 4 of the application can be performed according to the conventional molding, and the hot-pressing time is usually 420-480s, the water cooling time is 450-550s, and the hot-pressing temperature is 170-175℃.

[0049] In order to further illustrate the present application, the EVA chemical foaming sole material provided by the present application and the preparation method thereof are described in detail below in combination with examples, but they cannot be understood as limiting the protection scope of the present application. Examples

[0050] An air pressure supported EVA chemical foaming sole material, in mass parts, comprises the following components:

[0051] 100 parts of EVA composite elastomer material; 5 parts of gas barrier rubber; 0.42 parts of crosslinking agent; 7.8 parts of foaming agent; 0.5 parts of stearic acid; 1 part of zinc stearate; 1.5 parts of zinc oxide; 3.3 parts of filler.

[0052] The 100 parts of EVA composite elastomer is composed of 50 parts of EVA V33121, 45 parts of POE Engage 8003, and 5 parts of EPDM NORDEL IP 3745P, EVA V33121 is produced by Taiwan Yaguo, POE Engage 8003 and EPDM NORDEL IP 3745P are produced by Dow Chemical, USA; the gas barrier rubber is brominated butyl rubber, brand X2, produced by Lanxess, Germany; the crosslinking agent is BIBP (bis-tert-butyl peroxydiisopropylbenzene), produced by Guangzhou Fanguida; the foaming agent is azodicarbonamide, brand AC6000, produced by Fujian Jinlang New Material; and the filler is talc, produced by Xufeng Company.

[0053] A preparation method of an air pressure supported EVA chemical foaming sole, the added raw materials and their ratios are as described above, comprising the following steps:

[0054] Step 1: weigh each composition according to the above defined ratio, and then mix all the components except the crosslinking agent and the foaming agent, turn over 4-5 times, and control the temperature of the internal mixer at 120-125℃, then add the weighed crosslinking agent and foaming agent when mixing the blended material, continue mixing for 3-5 min, and finally granulate the uniformly mixed mixture, and place the prepared particles for cooling;

[0055] Step 2: according to the mold type, weigh a certain mass of the particles in step 1 and pour them into the mold cavity, after closing the mold, transfer the mold into the hot pressing hole, automatically hook the mold, and perform hot pressing and foaming, hot pressing for 600 s, hot pressing temperature 165-175℃,

[0056] Step 3: transfer the mold into the water cooling hole, mold water cooling for 600 s, open the mold to take out the inflated cold blank, and the ratio is about 1.1;

[0057] Step 4: The aerated cold foam in step 3 is subjected to temperature rising foaming in a transmission oven, and the total baking time is 30-33 min, to obtain a secondary molded small foam with a ratio of about 2.07;

[0058] Step 5: The molded small foam in step 4 is subjected to secondary mold pressing, the hot pressing time is 450 s, and the water cooling time is 500 s, to obtain a gas pressure supported EVA chemical foaming sole material. Embodiment

[0059] A gas pressure supported EVA chemical foaming sole material, by mass parts, comprises the following components:

[0060] 100 parts of EVA composite elastomer material; 5 parts of gas barrier rubber; 0.45 parts of crosslinking agent; 8 parts of foaming agent; 0.5 parts of stearic acid; 1 part of zinc stearate; 1.5 parts of zinc oxide; 3.3 parts of filler.

[0061] Wherein 100 parts of EVA composite elastomer is composed of 45 parts of EVA 7470M, 25 parts of POE Engage 8150, 20 parts of OBCs INFUSE 9507, and 10 parts of EPDM EPT 3092M, EVA 7470M is produced by Taiwan Formosa Plastics, POE Engage 8150 and OBCs INFUSE 9507 are produced by Dow Chemical, USA, and EPDM EPT 3092M is produced by Mitsui Chemicals, Japan; the gas barrier rubber is brominated butyl rubber, brand X2, produced by Lanxess, Germany; the crosslinking agent is BIBP (bis-tert-butyl peroxydiisopropylbenzene), produced by Guangzhou Fangxida; the foaming agent is azodicarbonamide, brand AC6000, produced by Fujian Jinlang New Material; and the filler is talc, produced by Xufeng Company.

[0062] A preparation method of a gas pressure supported EVA chemical foaming sole material, the added raw materials and their proportions are as described above, comprising the following steps:

[0063] Step 1: Weigh each component according to the proportions defined above, and then mix all components except the crosslinking agent and the foaming agent, and turn over the materials 4-5 times, with the mixing temperature controlled at 120-125°C; then add the weighed crosslinking agent and foaming agent during the mixing of the blended materials, and continue mixing for 3-5 min; finally, granulate the uniformly mixed mixture, and cool the prepared particles.

[0064] Step 2: Weigh a certain mass of the particles in step 1 according to the mold shape, pour them into the mold cavity, and then transfer the mold into the hot pressing hole after clamping, and automatically hook the mold to lock it, to perform hot pressing and foaming, with a hot pressing time of 600 s and a hot pressing temperature of 165-175°C.

[0065] Step 3: Turn the mold into the water cooling hole, mold water cooling for 600s, take out the inflated cold embryo, the ratio is about 1.15;

[0066] Step 4: The inflated cold embryo in step 3 is heated and foamed in a transmission oven, and the total baking time is 30-33min, to obtain a secondary molding small foam, the ratio is about 1.96;

[0067] Step 5: The molded small foam in step 4 is subjected to secondary molding, the hot pressing time is 480s, and the water cooling time is 500s, to obtain a gas pressure supported EVA chemical foaming shoe sole material. Embodiment

[0068] A gas pressure supported EVA chemical foaming shoe sole material, including the following components by mass fraction:

[0069] 100 parts of EVA composite elastomer material; 10 parts of gas barrier rubber; 0.5 parts of crosslinking agent, 9 parts of foaming agent; 0.5 parts of stearic acid; 1 part of zinc stearate; 2 parts of zinc oxide; 3.3 parts of filler.

[0070] The 100 parts of EVA composite elastomer is composed of 40 parts of EVA V33121, 10 parts of POE Infuse 9107, 25 parts of POE Engage 8003, 20 parts of TPEE Hytrel®4056, and 5 parts of EPDM NORDEL IP 3745P, wherein EVA V33121 is produced by Taiwan Yaguo, POE Engage 8003, Infuse 9107 and EPDM NORDEL IP 3745P are produced by Dow Chemical Company, TPEE Hytrel®4056 is produced by DuPont, and the EVA composite elastomer of the components is prepared by twin-screw melt blending; the gas barrier rubber is brominated butyl rubber with model X2, produced by Lanxess, Germany; the crosslinking agent is BIBP (bis-tert-butyl peroxydiisopropylbenzene), produced by Guangzhou Fanguida; the foaming agent is 7 parts of azodicarbonamide and 2 parts of modified H foaming agent, azodicarbonamide AC6000, and modified H foaming agent S12, both produced by Fujian Jinlang New Material; the filler is talc, produced by Xufeng Company.

[0071] A preparation method of a gas pressure supported EVA chemical foaming shoe sole material, the raw materials and their proportions are as described above, including the following steps:

[0072] Step 1: Each composition is weighed according to the above defined proportion, and all components except crosslinking agent and foaming agent are mixed and stirred for 4-5 times, with the mixing temperature controlled at 120-125℃. Then the mixed material is mixed with the weighed crosslinking agent and foaming agent, and stirred for another 3-5 min. Finally, the uniformly mixed material is granulated, and the granules are cooled.

[0073] Step 2: The granules in step 1 are weighed according to the mold shape, and poured into the mold cavity. After clamping, the mold is transferred to the hot pressing hole, and the automatic hook is locked. Hot pressing and foaming are performed, with a hot pressing time of 700s and a hot pressing temperature of 165-175℃.

[0074] Step 3: The mold is transferred to the water cooling hole, and the mold is cooled for 600s. The inflated cold blank is taken out, and the expansion ratio is about 1.06.

[0075] Step 4: The inflated cold blank in step 3 is heated and foamed in a transmission oven, with a total baking time of 30-33 min. A secondary molded small foam is obtained, with an expansion ratio of about 2.05.

[0076] Step 5: The molded small foam in step 4 is subjected to secondary molding, with a hot pressing time of 420s and a water cooling time of 500s. An air pressure supported EVA chemical foaming shoe sole material is obtained. Example

[0077] An air pressure supported EVA chemical foaming shoe sole material, including the following components in mass parts:

[0078] 100 parts of EVA composite elastomer material; 10 parts of gas barrier rubber; 0.5 parts of crosslinking agent, 9 parts of foaming agent; 0.5 parts of stearic acid; 1 part of zinc stearate; 2 parts of zinc oxide; 3.3 parts of filler.

[0079] The EVA composite elastomer is prepared by twin-screw melt blending, and the raw materials and their proportions are as follows: 100 parts of EVA composite elastomer is composed of 40 parts of EVA V33121, 10 parts of POE Infuse 9507, 25 parts of POE Engage 8150, 20 parts of Pebax 4033, and 5 parts of EPDM NORDEL IP 3745P, wherein EVA V33121 is produced by Taiwan Yaguo, POE Engage 8003, Infuse 9107, and EPDM NORDEL IP 3745P are produced by Dow Chemical Company of the United States, and Pebax 4033 is produced by Arkema of France; the gas barrier rubber is brominated butyl rubber with the brand X2 and is produced by Lanxess of Germany; the crosslinking agent is BIBP (bis-tert-butyl peroxydiisopropylbenzene) and is produced by Guangzhou Fangxida; the foaming agent is 7 parts of azodicarbonamide and 2 parts of modified H foaming agent, wherein azodicarbonamide AC6000 and modified H foaming agent S12 are both produced by Fujian Jinlang New Material; and the filler is talc powder produced by Xufeng Company.

[0080] A preparation method of an air pressure supported EVA chemical foaming shoe sole material, the raw materials and their proportions are as described above, and the method comprises the following steps:

[0081] Step 1: weigh each component according to the proportions defined above, and then mix all the components except the crosslinking agent and the foaming agent, and turn over the mixture for 4-5 times, with the mixing temperature controlled at 120-125°C; then add the weighed crosslinking agent and foaming agent to the mixed material, and continue mixing for 3-5 minutes; finally, granulate the uniformly mixed mixture, and cool the prepared granules.

[0082] Step 2: weigh a certain amount of the granules in step 1 according to the mold shape, and pour them into the mold cavity; after closing the mold, transfer the mold into a hot pressing hole, automatically hook the mold, and perform hot pressing and foaming, with the hot pressing time being 700 seconds and the hot pressing temperature being 165-175°C.

[0083] Step 3: transfer the mold into a water cooling hole, and perform mold water cooling for 600 seconds; then open the mold to take out the inflated cold blank, and the expansion ratio is about 1.1.

[0084] Step 4: perform temperature rising foaming on the inflated cold blank in step 3 in a transmission oven, and the total baking time is 30-33 minutes, so as to obtain a secondary molded small foam with an expansion ratio of about 2.1.

[0085] Step 5: perform secondary mold pressing on the molded small foam in step 4, with the hot pressing time being 420 seconds and the water cooling time being 500 seconds, so as to obtain the air pressure supported EVA chemical foaming shoe sole material.

[0086] A light weight EVA chemical foaming shoe sole material has the following formula:

[0087] 100 parts of EVA composite elastomer material; 5 parts of gas barrier rubber; 0.5 parts of crosslinking agent, 5.5 parts of foaming agent; 0.5 parts of stearic acid; 1 part of zinc stearate; 1.5 parts of zinc oxide; 3.3 parts of filler.

[0088] Wherein 100 parts of EVA composite elastomer is composed of 50 parts of EVA V33121, 45 parts of POE Engage 8003, 5 parts of EPDM NORDEL IP 3745P, EVA V33121 is produced by Taiwan Yaguo, POE Engage 8003 and EPDM NORDEL IP 3745P are produced by Dow Chemical, USA; the gas barrier rubber is brominated butyl rubber, brand X2, produced by Lanxess, Germany; the crosslinking agent is BIBP (bis-tert-butyl peroxydiisopropylbenzene), produced by Guangzhou Fanguida; the foaming agent is azodicarbonamide, brand AC6000, produced by Fujian Jinlang New Material; the filler is talc, produced by Xufeng Company.

[0089] A preparation method of a light EVA foamed sole material, the steps of which are as follows:

[0090] Step 1: weigh each composition according to the above defined proportion, then mix all the components except the crosslinking agent and the foaming agent, turn over 4-5 times, and control the temperature of the internal mixer at 120-125℃, then add the weighed crosslinking agent and foaming agent when mixing the blended material, continue mixing for 3-5 min, and finally granulate the uniformly mixed mixture, and place the prepared particles for cooling.

[0091] Step 2: take the particles in step 1 to perform small foaming, the mold temperature is about 165-175℃, and the vulcanization time is about 600 seconds, so that a small foaming blank with a ratio of about 2.05 can be obtained.

[0092] Step 3: perform secondary mold pressing of the shaped small foaming in step 2, the hot pressing time is 450s, and the water cooling time is 500s, so that a light EVA chemical foaming sole material is obtained.

[0093] An EVA chemical foaming sole material supported by air pressure, including the following components in mass parts:

[0094] 100 parts of EVA composite elastomer material; 10 parts of gas barrier rubber; 0.5 parts of crosslinking agent, 6 parts of foaming agent; 0.5 parts of stearic acid; 1 part of zinc stearate; 2 parts of zinc oxide; 3.3 parts of filler.

[0095] The 100 parts of EVA composite elastomer is composed of 40 parts of EVA V33121, 10 parts of POE Infuse 9107, 25 parts of POE Engage 8003, 20 parts of TPEE Hytrel 4056, and 5 parts of EPDM NORDEL IP 3745P, wherein the EVA V33121 is produced by Taiwan Yaguo, the POE Engage 8003, Infuse 9107, and EPDM NORDEL IP 3745P are produced by Dow Chemical, and the TPEE Hytrel 4056 is produced by DuPont; the gas barrier rubber is brominated butyl rubber with the brand X2 and is produced by Lanxess, Germany; the crosslinking agent is BIBP (bis-tert-butyl peroxydiisopropylbenzene) and is produced by Guangzhou Fanguida; the foaming agent is 4.5 parts of azodicarbonamide and 1.5 parts of modified H foaming agent, wherein the azodicarbonamide is AC6000, and the modified H foaming agent is S12, both of which are produced by Fujian Jinlang New Material; and the filler is talc powder produced by Xufeng Company.

[0096] A preparation method of a light EVA foamed sole material, the steps of which are as follows:

[0097] Step 1: weigh each component according to the above defined proportion, and then mix all the components except the crosslinking agent and the foaming agent, and turn over the materials for 4-5 times, with the mixing temperature controlled at 120-125°C; then add the weighed crosslinking agent and foaming agent to the mixed materials, and continue mixing for 3-5 minutes; finally, granulate the uniformly mixed materials, and cool the prepared granules;

[0098] Step 2: take the granules in step 1 to perform small foaming, with the mold temperature about 165-175°C and the vulcanization time about 600 seconds, so as to obtain a small foaming blank with a ratio of about 2.05.

[0099] Step 3: perform secondary mold pressing of the shaped small foaming in step 2, with the hot pressing time 420s and the water cooling time 500s, so as to obtain a light EVA chemical foaming sole material.

[0100] A light EVA chemical foaming sole material formula is as follows:

[0101] 100 parts of EVA composite elastomer material; 10 parts of gas barrier rubber; 0.5 parts of crosslinking agent, 5.8 parts of foaming agent; 0.5 parts of stearic acid; 1 part of zinc stearate; 1.5 parts of zinc oxide; and 3.3 parts of filler.

[0102] Wherein, wherein 100 parts of EVA composite elastomer is composed of 30 parts of EVA 7350M, 20 parts of EVA 7470M, 30 parts of POE Engage 8003, 15 parts of POE Engage 8450, 5 parts of EPDM NORDEL IP 3745P, wherein EVA 7350M, 7470M is produced by Taiwan Formosa in China, POE Engage 8003, POE Engage 8450, EPDM NORDEL IP 3745P is produced by American Dow; crosslinking agent is BIBP (bis-tert-butyl peroxide diisopropyl benzene), produced by Guangzhou Fangxilida; foaming agent is azodicarbonamide AC6000, produced by Fujian Jinlang New Material; filler is talc powder, produced by Xufeng Company.

[0103] A preparation method of light EVA foaming shoe sole material, the steps are as follows:

[0104] Step 1: weigh each composition according to the above defined proportion, then mix all components except crosslinking agent and foaming agent, turn over 4-5 times, the mixing temperature is controlled at 120-125 DEG C, then add the weighed crosslinking agent and foaming agent when mixing the blended material, continue mixing for 3-5 min, finally granulate the mixed material, and cool the prepared particles;

[0105] Step 2: take the particles in step 1 to carry out small foaming, the mold temperature is about 165-175 DEG C, and the vulcanization time is about 600 seconds, so that the small foaming blank is obtained, and the ratio is about 2.05.

[0106] Step 3: the formed small foaming in step 2 is subjected to secondary mold pressing, the hot pressing time is 420 s, and the water cooling time is 500 s, so that the light EVA chemical foaming shoe sole material is obtained.

[0107] The EVA foaming material prepared by the examples and the comparative examples is subjected to physical performance test, and the results are shown in Table 1:

[0108] Table 1: Performance test results of EVA foaming material of examples and comparative examples

[0109]

[0110] Remark:

[0111] The test method of compression average modulus (reference: Reciprocating Compression Properties and Life Prediction of Foamed Elastomer Materials): The median body weight 75 Kg is selected as the best reference object, because when running, the force of the runner on the insole is about 2 times the weight of the runner, so the maximum axial pressure of the test is 1500N. The landing time and take-off time of running are about 0.1s, the insole is stressed from 0 to 1500N and then to 0, and the emptying time is about 0.51s. The maximum load of the sample for reciprocating compression fatigue test is 1500N, and the frequency is 1.41Hz. The force-time setting of reciprocating compression is that the load is from 0 to 1500N in 0-0.1s, the load is from 1500N to 0 in 0.1-0.2s, the load is 0 in 0.2-0.71s, and the average value of the similar data is taken as the value of the load-displacement curve. In this application, the reciprocating compression is 200 times, and the data of 190 th 、195 th 、200 th The average value of the compression modulus of the three groups.

[0112] Generally, the stability of the insole is related to the hardness of the insole, and high hardness can ensure the stability of the insole, and the hardness is generally determined by the hardness of the base material and the density of the foamed material. In order to obtain higher rebound performance, the base material is usually selected to have relatively low hardness, which causes low hardness and difficulty in ensuring stability (such as Comparative Example 1). In order to achieve the effect of stability, high-performance elastomers need to be introduced into the formula, but due to the limited amount and chemical foaming process, it is also difficult to cause too much change in hardness support (such as Comparative Example 2). If the insole formula selects a base material with high hardness to ensure stability, due to the problem of chemical foaming process, it will cause poor rebound performance of the foamed material (such as Comparative Example 3). The traditional chemical foaming formula and process are difficult to balance the stability and rebound performance.

[0113] From the perspective of air pressure enhancement of the inflatable material, the insole material air pressure is increased by increasing the foaming agent and temperature control means in Embodiments 1-4, thereby greatly increasing the compression average modulus, obtaining higher average compression modulus at relatively low hardness, thereby ensuring the stability, greatly widening the selection range of the formula base material, and can balance the requirements of high rebound performance, and the increase of air volume and air pressure can further reduce the density and improve the rebound performance (Embodiments 1, 3 and Comparative Examples 1, 2).

[0114] According to the data in the above table, the EVA foamed material with air pressure support prepared in the application has excellent performance: the density is 0.08-0.09 g / cm3, the hardness is 40-43C, and the rebound is 69-78%, which can be comparable to the supercritical physical foaming shoe material, and the process is greatly simplified compared with the supercritical physical foaming.

[0115] The above merely preferred embodiments of the present application, it should be noted that for those of ordinary skill in the art, without departing from the principles of the present application, can also make a number of improvements and refinements, these improvements and refinements should also be considered within the scope of the present application.

Claims

1. An air pressure supporting EVA chemical foaming sole material, comprising the following components in parts by mass: 100 parts of an EVA composite elastomer material; 5-10 parts of a gas barrier rubber; 0.25-0.6 parts of a crosslinking agent; 6-10 parts of a foaming agent; 0.25-0.5 parts of stearic acid; 0.8-1.2 parts of zinc stearate; 1.2-2.5 parts of zinc oxide; 3-5 parts of a filler; wherein the EVA composite elastomer material is prepared by blending 40-60 parts of EVA; 40-60 parts of a polyolefin elastomer; and 0-20 parts of a new high-performance elastomer; the EVA has a VA mass content of 26%-40%; the polyolefin elastomer comprises one or more of POE, OBCs, EPDM, and SEBS; the new high-performance elastomer comprises one or more of thermoplastic polyurethane elastomer (TPU), polyester elastomer (TPEE), and nylon elastomer (PEBA); the gas barrier rubber is butyl rubber or halogenated butyl rubber with outstanding air tightness; the crosslinking agent is BIBP 1,4-bis-tert-butyl peroxyisopropyl benzene; the foaming agent is one or more of azodicarbonamide and modified foaming agent H; the filler is one or more of talc and calcium carbonate; a preparation method of the air pressure supporting EVA chemical foaming sole material, comprising the following steps: Step 1: weighing each component according to the defined proportions, mixing all components except the crosslinking agent and the foaming agent, then adding the weighed crosslinking agent and the foaming agent during the mixing of the blended material, and finally granulating the uniformly mixed material and placing the prepared granules for cooling; Step 2: weighing a certain mass of the granules in Step 1 according to the mold type, pouring the granules into the mold cavity, transferring the mold into a hot pressing hole after closing the mold, automatically hooking the mold, and performing hot pressing foaming; Step 3: transferring the mold into a water cooling hole, taking out the inflated cold blank after water cooling for a certain time; Step 4: performing temperature foaming of the inflated cold blank in Step 3 in a transmission oven to obtain a secondary molding small foam; Step 5: performing secondary molding of the molding small foam in Step 4 to obtain the air pressure supporting EVA chemical foaming sole material.

2. A preparation method of the air pressure supporting EVA chemical foaming sole material according to claim 1, comprising the following steps: Step 1: weighing each component according to the defined proportions, mixing all components except the crosslinking agent and the foaming agent, then adding the weighed crosslinking agent and the foaming agent during the mixing of the blended material, and finally granulating the uniformly mixed material and placing the prepared granules for cooling; Step 2: weighing a certain mass of the granules in Step 1 according to the mold type, pouring the granules into the mold cavity, transferring the mold into a hot pressing hole after closing the mold, automatically hooking the mold, and performing hot pressing foaming; Step 3: transferring the mold into a water cooling hole, taking out the inflated cold blank after water cooling for a certain time; Step 4: performing temperature foaming of the inflated cold blank in Step 3 in a transmission oven to obtain a secondary molding small foam; Step 5: the shaped small foams in step 4 are subjected to secondary molding to obtain air pressure supported EVA chemical foaming shoe sole material.

3. The method of claim 2, wherein the EVA chemical foamed shoe sole material is prepared by adding 0.1 to 0.5 parts by weight of the foaming agent to 100 parts by weight of the EVA resin, and then mixing the EVA resin and the foaming agent. The automatic hook locking mold of step 2 is a four-side hook to increase the mold closing sealing property and locking force; the hot pressing foaming is hot pressing plate temperature 170-180℃, hot pressing time 600-800s.

4. The method of claim 2, wherein the EVA chemical foamed shoe sole material is prepared by adding 0.1 to 0.5 parts by weight of the foaming agent to 100 parts by weight of the EVA resin, and then mixing the EVA resin and the foaming agent. The water cooling time of step 3 is 500-600s.

5. The method of claim 2, wherein the EVA chemical foamed shoe sole material is prepared by adding 0.1 to 0.5 parts by weight of the foaming agent to 100 parts by weight of the EVA resin, and then mixing the EVA resin and the foaming agent. The transmission oven parameter setting of step 4 is: temperature: first section 90℃, second section 80℃, third section 70℃, fourth section 60℃; baking time: whole process 30-40min.

6. The method for preparing a pneumatically supported EVA chemically foamed shoe sole as described in claim 2, characterized in that... The secondary molding of step 5 sets hot pressing time 420-480s, water cooling time 450-550s, and hot pressing temperature 170-175℃.

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