A foamed material for a functional insole and a method of manufacturing a functional insole

Abstract

The application discloses a foaming material for functional insoles and a preparation method of the functional insoles, and the foaming material comprises the following components in parts by mass: 25-35 parts of ethylene-vinyl acetate copolymer with a vinyl acetate mass ratio of 33%; 25-35 parts of modified long-chain nylon; 15-20 parts of polyolefin elastomer; 20-25 parts of hydrogenated styrene-butadiene block copolymer; 8-10 parts of filling aid; 0.4-0.5 parts of active agent; 0.5-1 parts of crosslinking agent; and 3-4 parts of foaming agent; wherein the modified long-chain nylon is obtained by graft modification of the following components in parts by mass: 45-55 parts of long-chain nylon with 12 carbon atoms in a molecular chain repeating unit; 45-55 parts of ethylene-vinyl acetate copolymer with a vinyl acetate mass ratio of 26%; 1-3 parts of toughening agent; and 0.5-0.8 parts of active agent. The foaming material has better fatigue resistance, and can improve the problem that the functional insole is not easy to recover at a long-term stress position.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of foaming materials, in particular to a foaming material for functional insoles and a preparation method of functional insoles. BACKGROUND

[0002] Functional insoles are generally made of foaming materials, which have the advantages of good resilience and good shock absorption effect. The foaming materials used in existing functional insoles are generally based on EVA, and additives and foaming agents are added for foaming. Then the foaming material is used to press and form the required functional insole by molding. However, when wearing the insole, the front palm and heel positions will always be under pressure. The current foaming material has poor fatigue resistance, which will cause the deformation of the front palm and heel stress positions to be difficult to recover. SUMMARY

[0003] The present application aims to overcome the above-mentioned defects or problems in the background art, and provide a foaming material for functional insoles and a preparation method of functional insoles, which has better fatigue resistance and can improve the problem of deformation of the long-term stress position of the functional insole.

[0004] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0005] Technical solution one: a foaming material for functional insoles, comprising the following components by mass fraction: ethylene-vinyl acetate copolymer 25-35 parts, the mass fraction of vinyl acetate in which is 33%; modified long-chain nylon 25-35 parts; polyolefin elastomer 15-20 parts; hydrogenated styrene-diene block copolymer 20-25 parts; filling aid 8-10 parts; active agent 0.4-0.5 parts; crosslinking agent 0.5-1 parts; foaming agent 3-4 parts; wherein the modified long-chain nylon is obtained by grafting modification of the following components by mass fraction: long-chain nylon 45-55 parts, the number of carbon atoms in the molecular chain repeat unit of which is 12; ethylene-vinyl acetate copolymer 45-55 parts, the mass fraction of vinyl acetate in which is 26%; toughening agent 1-3 parts; active agent 0.5-0.8 parts.

[0006] Technical solution two based on technical solution one: the modified long-chain nylon is completed by grafting modification by a double-screw stirrer, and the six segments of the double-screw stirrer are set to 160℃, 160℃, 165℃, 170℃, 175℃, and 175℃, respectively.

[0007] Technical solution three based on technical solution two: in the components of the modified long-chain nylon, the toughening agent is polyethylene maleic anhydride, and the active agent is stearic acid.

[0008] Based on the technical solution three, the fourth technical solution is that in the component of the foaming material, the filling aid includes the following components in mass fraction: talcum powder 4-5 parts; zinc stearate 0.6-0.8 parts; zinc oxide 1-1.5 parts; titanium white 2-5 parts.

[0009] Based on the fourth technical solution, the fifth technical solution is that in the component of the foaming material, the active agent is one or both of stearic acid and fatty acid.

[0010] Based on the fifth technical solution, the sixth technical solution is that in the component of the foaming material, the cross-linking agent is di-tert-butyl peroxide isopropyl benzene.

[0011] Based on the sixth technical solution, the seventh technical solution is that in the component of the foaming material, the foaming agent is azodicarbonamide.

[0012] Based on the seventh technical solution, the eighth technical solution is that in the component of the foaming material, the hydrogenated styrene-diene block copolymer is a linear block copolymer with a molecular weight of 600,000-800,000.

[0013] In addition, the present application also provides the ninth technical solution: a preparation method of a functional insole based on the component of the foaming material for the functional insole according to any one of the first to eighth technical solutions, which includes the following steps: step one: mixing long-chain nylon, ethylene-vinyl acetate copolymer, toughening agent and active agent, and grafting modification through a double-screw stirrer to obtain modified long-chain nylon; step two: mixing ethylene-vinyl acetate copolymer, modified long-chain nylon, polyolefin elastomer, hydrogenated styrene-diene block copolymer, active agent and foaming agent to obtain a first mixing product; step three: adding filling aid and cross-linking agent to the first mixing product and mixing to obtain a second mixing product; step four: foaming in a foaming mold using the second mixing product as raw material to obtain an insole preliminary blank; and step five: molding the insole preliminary blank through a forming mold to obtain the functional insole.

[0014] Based on the ninth technical solution, the tenth technical solution is that in the step one, the temperatures of the six sections of the double-screw stirrer are respectively set to 160℃, 160℃, 165℃, 170℃, 175℃ and 175℃; in the step two, the mixing temperature is 110-120℃ and the mixing time is 10-15 min; in the step three, the mixing temperature is 120-130℃ and the mixing time is 10-15 min; in the step four, the mold temperature of the foaming mold is 170-180℃ and the foaming time is 4-8 min; and in the step five, the mold temperature of the forming mold is 170-180℃ and the molding time is 8-10 min.

[0015] From the above description of the present application, the present application has the following beneficial effects compared with the prior art:

[0016] The application provides a foaming material for a functional insole, which is based on ethylene-vinyl acetate copolymer and polyolefin elastomer, and modified long-chain nylon and hydrogenated styrene-butadiene block copolymer are added, wherein the modified long-chain nylon is based on long-chain nylon, ethylene-vinyl acetate copolymer is added, and the long-chain nylon is modified by grafting, after the long-chain nylon is modified by ethylene-vinyl acetate copolymer, the softening point of the modified long-chain nylon is significantly reduced, the melt index is improved, the modified long-chain nylon can be better mixed with other components in the foaming material formula, and is synchronously punched at a proper temperature; the modified long-chain nylon can effectively improve the mechanical strength of the foaming material, and due to the modification, the nylon component can be uniformly mixed into the foaming system, so that the foaming material has good mechanical properties at different positions and can still restore the shape after long-term stress; meanwhile, the modified long-chain nylon can also cooperate with the added hydrogenated styrene-butadiene block copolymer, the unique hard segment and soft segment block combination structure of the hydrogenated styrene-butadiene block copolymer can soften the modified long-chain nylon, improve the flexibility of the foaming material, and due to the hydrogenation of the elastomer block in the hydrogenated styrene-butadiene block copolymer, the foaming material also has excellent aging resistance and can further enhance the fatigue resistance of the foaming material.

[0017] When the long-chain nylon is modified, the nylon species with 12 carbon atoms in the repeating unit of the molecular chain is adopted, so that the long-chain nylon can maintain a certain crystallinity and molecular chain regularity in the material system, which helps to provide a good balance between mechanical strength and toughness; meanwhile, in the grafting modification process, it can effectively chemically bond or physically entangle with the functional groups on the EVA molecular chain, thereby improving the compatibility between the two; and the modified long-chain nylon is applied to the foaming material, the suitable molecular chain structure enables the long-chain nylon to have a certain activity to buffer and disperse stress when subjected to repeated external force, while maintaining the relative stability of the overall structure, so as to effectively improve the fatigue resistance of the foaming material, so that the functional insole can better maintain the shape and performance during long-term use, especially at the frequently stressed parts such as the forefoot and heel. Among them, the VA mass fraction in the EVA is 26%, the EVA with the VA content can reduce the melting temperature of the long-chain nylon, so that the softening point of the long-chain nylon is significantly reduced and the melt index is improved, thereby improving the fluidity and plasticity of the long-chain nylon in the processing process, facilitating better mixing and reaction with other components, ensuring the smooth progress of the modification process, and improving the modification effect and efficiency.

[0018] In the formula of the foaming material, the mass percentage of VA in the EVA is 33%, and the higher content of vinyl acetate makes the EVA have more obvious rubber elasticity and flexibility, so that the foaming material can provide a soft and comfortable foot feeling for the functional insole, and better adapt to various movements and pressure changes of the foot during wearing, thereby effectively reducing the fatigue of the foot.

[0019] The specific six-stage temperature setting of the double screw mixer can accurately control the reaction temperature in the graft modification process of the modified long-chain nylon, and is beneficial to the full reaction of the components and improves the graft modification effect.

[0020] The toughening agent is polyethylene maleic anhydride, which can enhance the toughness of the modified long-chain nylon, so that the modified long-chain nylon is less likely to break under stress, and further improves the impact resistance and flexibility of the foaming material as a whole.

[0021] The hydrogenated styrene-butadiene block copolymer is a linear block copolymer with a molecular weight of 600,000-800,000, and the appropriate molecular weight range makes it effectively soften the modified long-chain nylon to improve the flexibility when it cooperates with the modified long-chain nylon, and also maintains the stability of its own structure, so that it can better play its role in improving the aging resistance and fatigue resistance of the foaming material as a whole. The molecular weight in this range helps to form a good micro-phase separation structure, so that the hard segment and the soft segment can play their respective roles, improving the comprehensive performance of the material and ensuring that the functional insole maintains good physical properties and appearance during long-term use.

[0022] In addition, the application also provides a preparation method of a functional insole, which first prepares a modified long-chain nylon through a double screw mixer graft modification, then mixes the modified long-chain nylon with ethylene-vinyl acetate copolymer and other components to obtain a first mixing product, then mixes a filling aid and a crosslinking agent into the first mixing product, the crosslinking agent fully plays a role to form a crosslinking structure, and then foaming is carried out to obtain an insole blank, at this time the insole blank has a large expansion ratio, and then the insole blank is compressed into a functional insole through a molding process. The functional insole is prepared by directly molding after foaming, so that the functional insole has good mechanical strength, resilience and fatigue resistance. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the application will be described clearly and completely below. Obviously, the described embodiments are preferred embodiments of the application, and should not be regarded as excluding other embodiments. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0024] In the claims, the specification, and drawings of the present application, terms such as "including" and "having," etc., are intended to be open-ended terms that allow for items to be included, etc., that are not listed.

[0025] The specification of the present application provides a foaming material for functional insole, which comprises the following components by mass fraction: ethylene-vinyl acetate copolymer 25-35 parts, the mass fraction of vinyl acetate is 33%; modified long chain nylon 25-35 parts; polyolefin elastomer 15-20 parts; hydrogenated styrene-butadiene block copolymer 20-25 parts; filling aid 8-10 parts; active agent 0.4-0.5 parts; crosslinking agent 0.5-1 parts; foaming agent 3-4 parts.

[0026] The modified long chain nylon is obtained by grafting modification of the following components by mass fraction: long chain nylon 45-55 parts, the number of carbon atoms in the molecular chain repeat unit is 12; ethylene-vinyl acetate copolymer 45-55 parts, the mass fraction of vinyl acetate is 26%; toughening agent 1-3 parts; active agent 0.5-0.8 parts. The long chain nylon is preferably a product with a brand of NE7035.

[0027] The modified long chain nylon is obtained by grafting modification of the following components by mass fraction: long chain nylon 45-55 parts, the number of carbon atoms in the molecular chain repeat unit is 12; ethylene-vinyl acetate copolymer 45-55 parts, the mass fraction of vinyl acetate is 26%; toughening agent 1-3 parts; active agent 0.5-0.8 parts. The long chain nylon is preferably a product with a brand of NE7035.

[0028] The components of the modified long chain nylon, the toughening agent is polyethylene maleic anhydride, and the active agent is stearic acid.

[0029] The components of the foaming material, the filling aid comprises the following components by mass fraction: talc 4-5 parts; zinc stearate 0.6-0.8 parts; zinc oxide 1-1.5 parts; titanium white powder 2-5 parts.

[0030] The components of the foaming material, the active agent is one or both of stearic acid and fatty acid.

[0031] The components of the foaming material, the crosslinking agent is di-tert-butyl peroxide isopropyl benzene. The di-tert-butyl peroxide isopropyl benzene, i.e. BIPB, is preferably a product with a brand of 14S-FL.

[0032] The components of the foaming material, the foaming agent is azodicarbonamide. The azodicarbonamide is preferably a product with a brand of AC3000.

[0033] The components of the foaming material, the hydrogenated styrene-butadiene block copolymer is a linear block copolymer with a molecular weight of 600,000-800,000. The hydrogenated styrene-butadiene block copolymer, i.e. SEBS, is preferably a product with a brand of YH530.

[0034] The formula of the foaming material described above is based on ethylene-vinyl acetate copolymer and polyolefin elastomer, and modified long-chain nylon and hydrogenated styrene-butadiene block copolymer are added. The modified long-chain nylon is based on long-chain nylon, and ethylene-vinyl acetate copolymer is added and obtained by graft modification. After the long-chain nylon is modified by ethylene-vinyl acetate copolymer, the softening point of the modified long-chain nylon is significantly reduced, and the melt index is increased, so that it can better blend with other components in the foaming material formula and be synchronized with the foaming process at a suitable temperature. The modified long-chain nylon can effectively improve the mechanical strength of the foaming material, and due to the modification, the nylon component can be uniformly mixed into the foaming system, so that the foaming material has good mechanical properties at different positions and can still recover its shape after long-term stress. At the same time, the modified long-chain nylon can also cooperate with the added hydrogenated styrene-butadiene block copolymer. The unique hard segment and soft segment block combination structure of the hydrogenated styrene-butadiene block copolymer can soften the modified long-chain nylon, improve the flexibility of the foaming material, and because the elastomer block in the hydrogenated styrene-butadiene block copolymer is hydrogenated, the foaming material also has excellent aging resistance, which can further enhance the fatigue resistance of the foaming material.

[0035] When modifying the long-chain nylon, the nylon species with 12 carbon atoms in the repeating unit of the molecular chain is used, so that the long-chain nylon can maintain a certain crystallinity and molecular chain regularity in the material system, which helps to provide a good balance between mechanical strength and toughness. At the same time, during the graft modification process, it can effectively chemically bond or physically entangle with the functional groups on the EVA molecular chain, thereby improving the compatibility between the two. And by applying this modified long-chain nylon to the foaming material, the appropriate molecular chain structure allows the long-chain nylon to have a certain activity to buffer and disperse stress when subjected to repeated external forces, while maintaining the relative stability of the overall structure, so as not to quickly produce cracks or permanent deformation due to stress concentration, thereby effectively improving the fatigue resistance of the foaming material, so that the functional insole can better maintain its shape and performance during long-term use, especially in the frequently stressed areas such as the forefoot and heel. The VA content in the EVA used is 26%, which can reduce the melting temperature of the long-chain nylon, significantly reduce its softening point, and increase its melt index, thereby improving the flowability and plasticity of the long-chain nylon during processing, facilitating better mixing and reaction with other components, ensuring the smooth progress of the modification process, and improving the modification effect and efficiency.

[0036] In the formula of the foaming material, the mass percentage of VA in the EVA used is 33%, and the higher content of vinyl acetate makes the EVA have more obvious rubber elasticity and flexibility. As a basic component in the foaming material, the EVA can provide a soft and comfortable foot feeling for the functional insole, better adapt to various movements and pressure changes of the foot during wearing, and effectively reduce the fatigue of the foot.

[0037] The specific six-stage temperature setting of the double screw mixer can accurately control the reaction temperature in the graft modification process of the modified long-chain nylon, which is beneficial to the full reaction of the components and improves the graft modification effect.

[0038] The toughening agent uses polyethylene maleic anhydride, which can enhance the toughness of the modified long-chain nylon, so that it is less likely to break under stress, and further improve the impact resistance and flexibility of the foaming material as a whole.

[0039] The hydrogenated styrene-butadiene block copolymer is a linear block copolymer with a molecular weight of 600,000-800,000. The appropriate molecular weight range enables it to effectively soften the modified long-chain nylon to improve flexibility while maintaining the stability of its own structure when it cooperates with the modified long-chain nylon, thereby better playing its role in improving the aging resistance and fatigue resistance of the entire foaming material. A molecular weight within this range helps to form a good micro-phase separation structure, allowing the hard segment and the soft segment to function separately, improving the overall performance of the material and ensuring that the functional insole maintains good physical properties and appearance during long-term use.

[0040] In addition, the specification of the present application also provides a preparation method of a functional insole, which comprises the following steps:

[0041] Step one: mix long-chain nylon, ethylene-vinyl acetate copolymer, toughening agent and active agent, and graft modify through a double screw mixer to obtain modified long-chain nylon;

[0042] Step two: mix ethylene-vinyl acetate copolymer, modified long-chain nylon, polyolefin elastomer, hydrogenated styrene-butadiene block copolymer, active agent and foaming agent to obtain a first mixing product;

[0043] Step three: add a filling aid and a crosslinking agent to the first mixing product and mix to obtain a second mixing product;

[0044] Step four: use the second mixing product as raw material to perform foaming in a foaming mold to obtain an insole blank;

[0045] Step five: mold the insole blank through a molding mold to obtain the functional insole.

[0046] In the step one, the six segments of the double screw stirrer are set to 160℃, 160℃, 165℃, 170℃, 175℃ and 175℃ respectively; in the step two, the mixing temperature is 110-120℃ and the mixing time is 10-15min; in the step three, the mixing temperature is 120-130℃ and the mixing time is 10-15min; in the step four, the mold temperature of the foaming mold is 170-180℃ and the foaming time is 4-8min; in the step five, the mold temperature of the forming mold is 170-180℃ and the mold pressing time is 8-10min.

[0047] The preparation method of the functional insole provided by the application comprises the following steps: first, preparing modified long-chain nylon through double screw stirrer graft modification; then, mixing the modified long-chain nylon with ethylene-vinyl acetate copolymer and other components to obtain a first mixing product; then, mixing filling aids and cross-linking agents into the first mixing product, so that the cross-linking agents fully play a role to form a cross-linking structure; then, foaming to obtain an insole blank; at this time, the insole blank has a large expansion ratio; and finally, compressing the insole blank through a mold pressing forming process to obtain the functional insole. Through the method of directly mold pressing forming after foaming, the functional insole obtained has good mechanical strength, resilience and fatigue resistance.

[0048] To further illustrate the technical effects of the foaming material for functional insoles and the preparation method thereof provided by the application, the following examples and comparative examples are provided by the embodiments of the application.

[0049] Example 1

[0050] The foaming material for functional insoles provided by Example 1 comprises the following components in parts by mass:

[0051] 25 parts of ethylene-vinyl acetate copolymer with a vinyl acetate mass ratio of 33%; 25 parts of modified long-chain nylon; 15 parts of polyolefin elastomer; 20 parts of hydrogenated styrene-diene block copolymer; 8 parts of filling aid; 0.4 parts of active agent; 0.5 parts of cross-linking agent; and 3 parts of foaming agent; wherein the modified long-chain nylon is obtained by graft modification of the following components in parts by mass: 45 parts of long-chain nylon with 12 carbon atoms in the molecular chain repeating unit; 45 parts of ethylene-vinyl acetate copolymer with a vinyl acetate mass ratio of 26%; 1 part of toughening agent; and 0.5 parts of active agent.

[0052] The filling aid includes the following components by mass fraction: talcum powder 4 parts; zinc stearate 0.6 parts; zinc oxide 1 part; titanium white 2 parts. In the components of the modified long-chain nylon, the toughening agent is polyethylene maleic anhydride, and the active agent is stearic acid. In the components of the foaming material, the active agent is stearic acid, the crosslinking agent is di-t-butyl peroxide isopropyl benzene, the foaming agent is azodicarbonamide, and the hydrogenated styrene-butadiene block copolymer is a product with a brand YH530. The modified long-chain nylon is grafted and modified by a double-screw stirrer, and the six segments of the double-screw stirrer are set to 160℃, 160℃, 165℃, 170℃, 175℃, and 175℃ respectively.

[0053] In addition, the embodiment 1 also provides a preparation method of the functional insole based on the components of the foaming material, which includes the following steps:

[0054] Step one: mixing the long-chain nylon, ethylene-vinyl acetate copolymer, toughening agent, and active agent, and grafting and modifying by a double-screw stirrer to obtain the modified long-chain nylon;

[0055] Step two: mixing the ethylene-vinyl acetate copolymer, modified long-chain nylon, polyolefin elastomer, hydrogenated styrene-butadiene block copolymer, active agent, and foaming agent to obtain a first mixing product;

[0056] Step three: adding the filling aid and crosslinking agent to the first mixing product and mixing to obtain a second mixing product;

[0057] Step four: foaming the second mixing product in a foaming mold to obtain an insole blank;

[0058] Step five: molding the insole blank by a molding mold to obtain the functional insole.

[0059] In the step one, the six segments of the double-screw stirrer are set to 160℃, 160℃, 165℃, 170℃, 175℃, and 175℃ respectively; in the step two, the mixing temperature is 110℃ and the mixing time is 10 minutes; in the step three, the mixing temperature is 120℃ and the mixing time is 10 minutes; in the step four, the mold temperature of the foaming mold is 170℃ and the foaming time is 4 minutes; and in the step five, the mold temperature of the molding mold is 170℃ and the molding time is 8 minutes.

[0060] Embodiment 2

[0061] The foaming material for the functional insole provided by the embodiment 2 includes the following components by mass fraction:

[0062] Ethylene-vinyl acetate copolymer 30 parts, vinyl acetate content 33%; modified long chain nylon 30 parts; polyolefin elastomer 17.5 parts; hydrogenated styrene-butadiene block copolymer 22.5 parts; filling aid 9 parts; active agent 0.45 parts; crosslinking agent 0.75 parts; foaming agent 3.5 parts; wherein the modified long chain nylon is obtained by grafting modification of the following components: long chain nylon 50 parts, the number of carbon atoms in the molecular chain repeat unit is 12; ethylene-vinyl acetate copolymer 50 parts, vinyl acetate content 26%; toughening agent 2 parts; active agent 0.65 parts.

[0063] The filling aid includes the following components: talc 4.5 parts; zinc stearate 0.7 parts; zinc oxide 1.25 parts; titanium white 3.5 parts. In the components of the modified long chain nylon, the toughening agent is polyethylene maleic anhydride, and the active agent is stearic acid. In the components of the foaming material, the active agent is stearic acid, the crosslinking agent is di-t-butyl peroxide isopropyl benzene, the foaming agent is azodicarbonamide, and the hydrogenated styrene-butadiene block copolymer is selected from the product of grade YH530. The modified long chain nylon is completed by grafting modification by a double screw stirrer, and the six segments of the double screw stirrer are set to 160°C, 160°C, 165°C, 170°C, 175°C, and 175°C, respectively.

[0064] In addition, Example 2 also provides a method for preparing a functional insole based on the components of the above foaming material, which includes the following steps:

[0065] Step one: mix long chain nylon, ethylene-vinyl acetate copolymer, toughening agent, and active agent, and graft modify by a double screw stirrer to obtain modified long chain nylon;

[0066] Step two: mix ethylene-vinyl acetate copolymer, modified long chain nylon, polyolefin elastomer, hydrogenated styrene-butadiene block copolymer, active agent, and foaming agent to obtain a first mixing product;

[0067] Step three: add filling aid and crosslinking agent to the first mixing product and mix to obtain a second mixing product;

[0068] Step four: use the second mixing product as raw material to perform foaming in a foaming mold to obtain an insole blank;

[0069] Step five: mold the insole blank through a forming mold to obtain the functional insole.

[0070] The six segments of the double screw stirrer in the step one are set at 160℃, 160℃, 165℃, 170℃, 175℃ and 175℃ respectively; the mixing temperature in the step two is 115℃, and the mixing time is 12.5 min; the mixing temperature in the step three is 125℃, and the mixing time is 12.5 min; the mold temperature of the foaming mold in the step four is 175℃, and the foaming time is 6 min; the mold temperature of the forming mold in the step five is 175℃, and the mold pressing time is 9 min.

[0071] Example 3

[0072] The foaming material for the functional insole provided in Example 3 comprises the following components by mass fraction:

[0073] 35 parts of ethylene-vinyl acetate copolymer with a vinyl acetate mass fraction of 33%; 35 parts of modified long-chain nylon; 20 parts of polyolefin elastomer; 25 parts of hydrogenated styrene-butadiene block copolymer; 10 parts of filling aid; 0.5 part of active agent; 1 part of crosslinking agent; and 4 parts of foaming agent; wherein the modified long-chain nylon is obtained by graft modification of the following components by mass fraction: 55 parts of long-chain nylon with 12 carbon atoms in the molecular chain repeating unit; 55 parts of ethylene-vinyl acetate copolymer with a vinyl acetate mass fraction of 26%; 3 parts of toughening agent; and 0.8 part of active agent.

[0074] The filling aid comprises the following components by mass fraction: 5 parts of talc; 0.8 part of zinc stearate; 1.5 parts of zinc oxide; and 5 parts of titanium white. In the components of the modified long-chain nylon, the toughening agent is polyethylene maleic anhydride, and the active agent is stearic acid. In the components of the foaming material, the active agent is stearic acid, the crosslinking agent is di-tert-butyl peroxide isopropyl benzene, the foaming agent is azodicarbonamide, and the hydrogenated styrene-butadiene block copolymer is selected from the product with the trade name YH530. The modified long-chain nylon is obtained by graft modification through a double screw stirrer, and the six segments of the double screw stirrer are set at 160℃, 160℃, 165℃, 170℃, 175℃ and 175℃ respectively.

[0075] In addition, Example 3 also provides a preparation method of the functional insole based on the components of the foaming material, which comprises the following steps:

[0076] Step one: mixing long-chain nylon, ethylene-vinyl acetate copolymer, toughening agent and active agent, and performing graft modification through a double screw stirrer to obtain modified long-chain nylon;

[0077] Step two: mixing ethylene-vinyl acetate copolymer, modified long-chain nylon, polyolefin elastomer, hydrogenated styrene-butadiene block copolymer, active agent and foaming agent to obtain a first mixing product;

[0078] Step three: adding a filling aid and a cross-linking agent into the first mixing product to mix, obtaining a second mixing product;

[0079] Step four: foaming in a foaming mold with the second mixing product as raw material, obtaining a shoe-pad preliminary blank;

[0080] Step five: molding the shoe-pad preliminary blank through a molding mold, obtaining the functional shoe-pad.

[0081] In the step one, the six-section temperature of the double-screw stirrer is set as 160℃, 160℃, 165℃, 170℃, 175℃ and 175℃ respectively; in the step two, the mixing temperature is 120℃ and the mixing time is 15 min; in the step three, the mixing temperature is 130℃ and the mixing time is 15 min; in the step four, the mold temperature of the foaming mold is 180℃ and the foaming time is 8 min; in the step five, the mold temperature of the molding mold is 180℃ and the molding time is 10 min.

[0082] Comparative Example 1

[0083] Comparative Example 1 is based on Example 2, and the difference is that the long-chain nylon is directly used without modification, and the mass fraction is 35 parts.

[0084] Comparative Example 2

[0085] Comparative Example 2 is based on Example 2, and the difference is that the EVA with a VA content of 18% is used in the modified long-chain nylon.

[0086] Comparative Example 3

[0087] Comparative Example 3 is based on Example 2, and the difference is that in the components of the foaming material, the mass fraction of the modified long-chain nylon is 15 parts.

[0088] The same size functional shoe-pads prepared by the above Examples 1-3 and Comparative Examples 1-3 are detected for physical properties and appearance, and the detection results are as follows:

[0089]

[0090] In the fatigue resistance detection, the same size functional shoe-pads prepared by Examples 1-3 and Comparative Examples 1-3 are used as samples, a foot model is placed on the sample, and a pressure of 30 kg is applied to the foot model for 2 hours. Then, the foot model is removed, and the deformation recovery of the sample at the forefoot and heel is observed. According to the above test results, it can be known that the foaming material for functional shoe-pads provided by the present application has very excellent fatigue resistance while maintaining good resilience, and can effectively improve the problem that the deformation at the long-term stress position of the functional shoe-pad is not easy to recover.

[0091] The above description and the examples are intended to explain the scope of the present application, but not to limit the scope of the present application. Modifications, equivalent replacements or other improvements based on the conception of the present application or the above examples, which can be obtained by those skilled in the art with common knowledge, common technical knowledge and / or prior art, through logical analysis, reasoning or limited tests, shall be included in the scope of the present application.

Claims

1. A foamed material for functional insoles, characterized in that, The components include the following parts by weight: 25-35 parts of ethylene-vinyl acetate copolymer, of which vinyl acetate accounts for 33% by mass; 25-35 parts of modified long-chain nylon; 15-20 parts of polyolefin elastomer; 20-25 parts of hydrogenated styrene-butadiene block copolymer; 8-10 parts of filler; 0.4-0.5 parts of activator; 0.5-1 part of crosslinking agent; 3-4 parts of foaming agent; The modified long-chain nylon is obtained by grafting modification of the following components in parts by weight: 45-55 parts of long-chain nylon, in which the number of carbon atoms in the repeating unit of the molecular chain is 12; 45-55 parts of ethylene-vinyl acetate copolymer, in which the mass percentage of vinyl acetate is 26%; 1-3 parts of toughening agent; and 0.5-0.8 parts of activator. The modified long-chain nylon was grafted and modified using a twin-screw mixer, with the six temperature settings of the twin-screw mixer being 160℃, 160℃, 165℃, 170℃, 175℃, and 175℃, respectively. In the modified long-chain nylon, the toughening agent is polyethylene maleic anhydride and the activator is stearic acid.

2. The foamed material for functional insoles as described in claim 1, characterized in that, The foaming material comprises the following components in parts by weight: 4-5 parts talc; 0.6-0.8 parts zinc stearate; 1-1.5 parts zinc oxide; 2-5 parts titanium dioxide.

3. The foamed material for functional insoles as described in claim 1, characterized in that, The active agent in the foaming material is one or two of stearic acid and fatty acids.

4. The foamed material for functional insoles as described in claim 1, characterized in that, In the components of the foaming material, the crosslinking agent is di-tert-butylperoxyisopropylbenzene.

5. The foamed material for functional insoles as described in claim 1, characterized in that, The foaming agent in the foaming material is azodicarbonamide.

6. The foamed material for functional insoles as described in claim 1, characterized in that, In the components of the foaming material, the hydrogenated styrene-butadiene block copolymer is a linear block copolymer with a molecular weight of 600,000 to 800,000.

7. A method for preparing a functional insole, based on the components of the foaming material for functional insoles according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Mix long-chain nylon, ethylene vinyl acetate copolymer, toughening agent and activator, and perform graft modification using a twin-screw mixer to obtain modified long-chain nylon; Step 2: Mix ethylene vinyl acetate copolymer, modified long-chain nylon, polyolefin elastomer, hydrogenated styrene-butadiene block copolymer, activator, and foaming agent to obtain the first compound product; Step 3: Add filler and crosslinking agent to the first compound product and mix to obtain the second compound product; Step 4: Using the second compound product as raw material, foam it in a foaming mold to obtain the initial insole blank; Step 5: The insole blank is molded into shape using a molding die to obtain the functional insole.

8. The method for preparing a functional insole as described in claim 7, characterized in that, In step one, the six temperature settings of the twin-screw mixer are 160℃, 160℃, 165℃, 170℃, 175℃, and 175℃, respectively. In step two, the mixing temperature is 110-120℃, and the mixing time is 10-15 minutes. In step three, the mixing temperature is 120-130℃, and the mixing time is 10-15 minutes. In step four, the mold temperature of the foaming mold is 170-180℃, and the foaming time is 4-8 minutes. In step five, the mold temperature of the molding mold is 170-180℃, and the molding time is 8-10 minutes.

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