Elastic foaming material

Abstract

The invention belongs to the technical field of foaming materials, and particularly relates to an elastic foaming material which is obtained by stacking at least two layers of materials C, coating a raw material B between the at least two layers of materials C at intervals and then performing primary vulcanization, and the materials C are obtained by performing banburying and open milling on the raw material A; wherein the raw material A comprises 50%-75% of an ethylene-vinyl acetate copolymer, 1%-10% of a foaming agent and 0.01%-3% of a cross-linking agent; the raw material B comprises 20%-40% of first graphene, 8%-10% of polyethylene glycol, 2%-5% of polyvinylpyrrolidone, 0.5%-1.5% of ethylene glycol, 6%-10% of sodium carboxymethyl cellulose, 3%-5% of ammonia water and water. The foaming material is light and high in elasticity, the elasticity and the buffering performance are effectively improved, the foaming material which is high in elasticity, high in buffering performance and lighter can be obtained, and then the foaming material can be used in the fields of high-elasticity shoe soles, damping materials and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of foaming materials, and particularly relates to an elastic foaming material. Background Art

[0002] Due to its light weight and good softness, foaming materials have functions such as buffering, sound absorption, shock absorption, heat preservation, and filtration, and are widely used in the manufacture of sports equipment, seat cushions, children's floors, sports shoes, etc. Among them, there are different problems in the application of foaming soles made of different materials. For example, the mechanical strength, tear resistance, and peel resistance of EVA foaming soles are not good enough; therefore, the application of foaming materials in soles is restricted to a certain extent. Graphene has a unique two-dimensional periodic honeycomb lattice structure. The existence of stable carbon hexagons in its structural units endows it with excellent thermal, mechanical, and electrical properties; therefore, adding graphene to foaming materials can effectively improve the mechanical properties such as tear resistance and peel resistance of foaming soles, thereby broadening the application scope of soles.

[0003] However, the existing foaming materials do not have enough elasticity to meet the requirements in special applications such as high-elastic soles and high-elastic shock-absorbing materials. Moreover, when graphene is applied in foaming materials, the specific surface area of graphene is extremely large and there is an inherent van der Waals force between the sheets, so graphene is extremely easy to agglomerate; at the same time, ethylene-vinyl acetate copolymer and the like have low polarity and poor compatibility with graphene, resulting in it being difficult for graphene to be exfoliated in ethylene-vinyl acetate copolymer. Therefore, simply adding graphene to foaming materials has an insignificant effect on improving the performance of foaming materials.

[0004] It should be noted that this part of the content of the present invention only provides background technology related to the present invention, and does not necessarily constitute prior art or well-known technology. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the existing foaming materials with insufficient elasticity and unsatisfactory buffering effect, and provide an elastic foaming material. The foaming material of the present invention is light and highly elastic, effectively improving the elasticity and buffering performance, facilitating the acquisition of foaming materials with high elasticity, high buffering performance, and being more lightweight, and can further be used in fields such as high-elastic soles and shock-absorbing materials, further broadening the application scenarios of foaming materials.

[0006] To achieve the above purpose, the present invention provides an elastic foaming material, which is obtained by laminating at least two layers of material C, and coating raw material B at intervals between at least two layers of material C, and then performing primary vulcanization. Material C is obtained by kneading and open-kneading raw material A; Among them, based on the weight percentage of each component contained in raw material A, raw material A contains 50%-75% of ethylene-vinyl acetate copolymer, 1%-10% of foaming agent, and 0.01%-3% of cross-linking agent; Based on the weight percentage of each component contained in raw material B, raw material B contains 20% - 40% of the first graphene, 8% - 10% of polyethylene glycol, 2% - 5% of polyvinylpyrrolidone, 0.5% - 1.5% of ethylene glycol, 6% - 10% of sodium carboxymethyl cellulose, 3% - 5% of ammonia water, and water.

[0007] In some preferred embodiments of the present invention, the total coated area of raw material B accounts for 20% - 80% of the surface area of material C.

[0008] In some preferred embodiments of the present invention, in the X-axis direction of material C, the distance between adjacent coated raw material B is 1 - 50 mm; in the Y-axis direction of material C, the distance between adjacent coated raw material B is 1 - 50 mm.

[0009] In some preferred embodiments of the present invention, the elastic foaming material has micropores at the position where raw material B is coated, and the size of the micropores is 0.1 - 10 mm.

[0010] In some preferred embodiments of the present invention, the ratio of the coating thickness of raw material B to the thickness of adjacent material C is 0.001 - 0.5:1, and / or the coating thickness of raw material B is 1 - 1200 μm.

[0011] In some preferred embodiments of the present invention, based on the weight percentage of each component contained in raw material A, raw material A further contains 0.5% - 23% of a foaming promoter and 3% - 20% of a filler.

[0012] Further preferably, the foaming promoter includes at least one of stearic acid, zinc stearate, and zinc oxide. Based on the weight percentage of the corresponding component contained in raw material A, when containing stearic acid, the content of stearic acid is 0.1% - 2%, when containing zinc stearate, the content of zinc stearate is 0.1% - 2%, and when containing zinc oxide, the content of zinc oxide is 0.5% - 20%.

[0013] Further preferably, the filler includes calcium powder and / or talc powder.

[0014] Further preferably, in raw material A, the crosslinking agent includes dicumyl peroxide and / or azodicarbonamide.

[0015] In some preferred embodiments of the present invention, raw material A further contains second graphene, and the mass dosage of the second graphene is 1% - 5% of the total mass of other components in raw material A except the second graphene. In some preferred embodiments of the present invention, the process of kneading raw material A includes: kneading ethylene-vinyl acetate copolymer, filler, and second graphene for the first time, and then adding blowing agent, crosslinking agent, and blowing accelerator for the second kneading; wherein, the first kneading time is 3-15 min, the second kneading time is 1-8 min, and the temperatures of the first kneading and the second kneading are independently 110°C-170°C.

[0016] In some preferred embodiments of the present invention, based on the weight percentage content of raw material A, raw material A further contains 5%-20% of polyolefin elastomer, 3%-15% of thermoplastic elastomer, 0%-2%, more preferably 0.1%-2% of additives.

[0017] In some preferred embodiments of the present invention, the process of kneading raw material A includes: kneading ethylene-vinyl acetate copolymer, polyolefin elastomer, thermoplastic elastomer, filler, and additives for the first kneading, and then adding blowing agent, crosslinking agent, and blowing accelerator for the second kneading, wherein, the first kneading time is 3-15 min, the second kneading time is 1-8 min, and the temperatures of the first kneading and the second kneading are independently 110°C-160°C.

[0018] In some preferred embodiments of the present invention, the thermoplastic elastomer is selected from at least one of ethylene-methyl acrylate copolymer, styrene-ethylene-butene-styrene copolymer, styrene-butene-styrene copolymer, and thermoplastic polyurethane, and the additives are selected from at least one of flow additives and active additives.

[0019] In some preferred embodiments of the present invention, the conditions for open milling include: the open milling temperature is 80-100°C, and the open milling time is 7-10 min; the conditions for the first vulcanization include: the vulcanization temperature is 165°C-185°C, and the vulcanization time is 20-25 min.

[0020] In some preferred embodiments of the present invention, secondary vulcanization is also carried out after the vulcanization, and the conditions for the secondary vulcanization include: the temperature is 150-160°C, and the time is 5-10 min.

[0021] Beneficial effects: The present invention, through the above technical scheme, especially using the raw materials A and B of specific composition in combination with the above specific preparation method, can foam at the coating position between at least two layers of material C, thereby obtaining a lightweight foam material with good recovery performance and high elasticity, effectively improving the elasticity and cushioning performance of the foam material, while further reducing the density, which is conducive to obtaining a foam material with high elasticity, high cushioning performance and lighter weight, and can be used in the fields of high-elastic soles, shock-absorbing materials, etc., further broadening the application scenarios of foam materials. A possible principle guess is: the raw material B contains the first graphene and six solvents, and the first graphene plays the role of anti-crosslinking and isolation as a pore-forming material, and because the organic solvent contained in the vulcanization process volatilizes, a high-pressure static pressure is generated, and the first graphene is propped up in an instant (such as about 10 minutes), and the first graphene will stick to the wall of material C when it is opened to play a supporting role, giving greater elasticity, so that the first graphene can fully and evenly foam in the vulcanization process, thereby obtaining high elasticity and excellent recovery performance. Under the same conditions, if the first graphene in raw material B is directly added to raw material A, it will lead to failure of pore formation and foaming and poor elasticity.

[0022] The present invention adopts raw material A of suitable composition to prepare material C, and combines with raw material B of suitable composition to obtain a foaming material with middle supporting holes, which is beneficial to improving the elasticity of the foaming material while ensuring the cushioning performance of the foaming material.

[0023] Moreover, it has been found through research that graphene is prone to agglomeration due to its large specific surface area and strong van der Waals force. It is usually difficult for a single solvent to completely overcome the strong interaction between graphene sheets. In this regard, the present invention uses a variety of solvents to cooperate with each other, which can interact with the surface of the graphene sheets through different components, thereby reducing the attraction between the sheets and improving its dispersion stability in the solvent. A possible principle guess is that polyethylene glycol and polyvinyl pyrrolidone can form a stable shell through physical adsorption or chemical bonding to prevent the agglomeration of graphene; cooperate with ammonia water to provide an alkaline environment, so that the graphene surface is negatively charged, generating electrostatic repulsion, and preventing the graphene sheets from approaching each other and agglomerating; cooperate with sodium carboxymethyl cellulose, which can provide a steric hindrance effect and further inhibit the agglomeration of the sheets.

[0024] In a preferred embodiment of the present invention, an appropriate amount of second graphene is added to raw material A, which is more conducive to improving the support and elasticity of material C. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 This is an electron microscope image showing the length measurement of micropores in a high-elastic sole material according to an embodiment of the present invention.

[0027] Figure 2 for Figure 1 Electron microscopic image of micropore width measurement. DETAILED DESCRIPTION

[0028] In the present invention, unless otherwise specified, directional words such as "upper, lower, left, right" are generally understood in conjunction with the directions shown in the drawings and actual applications.

[0029] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0030] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0031] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article. Among them, the terms "optional" and "optional" all mean that they may be included or not included (or may be present or not).

[0032] The present invention provides an elastic foaming material, which is obtained by laminating at least two layers of material C, coating raw material B at intervals between at least two layers of material C, and then performing primary vulcanization. Material C is obtained by kneading and open-milling raw material A.

[0033] In the description of the present invention, "laminating at least two layers of material C and coating raw material B at intervals between at least two layers of material C", the order of lamination and coating is not limited. That is, material C can be laminated first and then raw material B can be coated, or raw material B can be coated on the surface of at least one layer of material C first and then laminated with another part of material C, or multiple laminations and multiple coatings can be alternately arranged, which can be specifically determined according to actual needs. During the vulcanization process, micropores are formed at the places where raw material B is coated.

[0034] Among them, based on the weight percentage of each component contained in raw material A, raw material A contains 50%-75% of ethylene-vinyl acetate copolymer, 1%-10% of foaming agent, and 0.01%-3% of crosslinking agent. By using raw material A with a suitable composition, it can be uniformly mixed, ensuring the foaming effect and facilitating the formation of effective support and elasticity.

[0035] Based on the weight percentage of each component contained in raw material B, raw material B contains 20%-40% of first graphene, 8%-10% of polyethylene glycol, 2%-5% of polyvinylpyrrolidone, 0.5%-1.5% of ethylene glycol, 6%-10% of sodium carboxymethylcellulose, 3%-5% of ammonia water, and water. By using raw material B with a suitable composition, large bubbles can be instantaneously generated during the vulcanization process, which is beneficial to the effective support of graphene, and thus high elastic performance and excellent recovery performance can be obtained.

[0036] In the present invention, the larger the coating area of raw material B and the more pores are formed, and the coating area of raw material B can be adjusted according to the pore formation situation required for the desired elasticity. In some preferred embodiments of the present invention, the total coating area of raw material B accounts for 20%-80%, preferably 25%-80% of the surface area of material C, which is more conducive to obtaining a sufficient number of and appropriately large micropores, and thus a highly elastic foaming material can be obtained.

[0037] In some preferred embodiments of the present invention, in the X-axis direction of material C, the distance between adjacent coated raw material B is 1-50 mm, preferably 7-50 mm; in the Y-axis direction of material C, the distance between adjacent coated raw material B is 1-50 mm, preferably 7-50 mm. Coating raw material B at a suitable distance is more conducive to obtaining the distribution requirements of the pore structure.

[0038] In some preferred embodiments of the present invention, the elastic foam material has micropores at the position of coating raw material B, and the size of the micropores is 0.1-10mm. It is understood that the micropores refer to the millimeter-level pores (i.e., macropores) formed by the elastic foam material at the position of coating raw material B due to foaming, rather than the micron-level pores (small pores) contained in the foam material itself. The size of the micropores in any direction is within the range of 0.1-10mm. Further preferably, the length and width of the micropores are (0.5-5mm)×(0.5-10mm). The present invention uses micropores of appropriate size, which is more conducive to obtaining a foam material that meets the requirements of both elasticity and recovery performance.

[0039] In some preferred embodiments of the present invention, the ratio of the coating thickness of the raw material B to the thickness of the adjacent material C is 0.001-0.5:1, preferably 0.01-0.30:1, and more preferably 0.01-0.20:1. The preferred ratio is more conducive to the pore formation and pore size control of the porous material, and ensures the adhesion between the adjacent materials C, thereby further improving the elasticity and cushioning performance of the foaming material, while further reducing the density, which is conducive to obtaining a foaming material with high elasticity, high cushioning performance and lighter weight.

[0040] Preferably, the coating thickness of the raw material B is 1-1200 μm, more preferably 1-900 μm, and more preferably 50-500 μm. The preferred coating thickness is more conducive to balancing the instantaneous propping effect during foaming and the supporting effect of graphene on the pores after foaming.

[0041] In some preferred embodiments of the present invention, based on the weight percentage of each component contained in raw material A, raw material A further comprises 0.5%-23% of a foaming promoter and 3%-20% of a filler, and the filler is preferably 5%-20%. This preferred solution is more conducive to improving the foaming uniformity of the foaming material and the supporting performance of the foaming material.

[0042] Further preferably, the foaming promoter includes at least one of stearic acid, zinc stearate and zinc oxide.

[0043] Further preferably, based on the weight percentage of the corresponding components contained in raw material A, the content of stearic acid is 0.1%-2% when stearic acid is contained, the content of zinc stearate is 0.1%-2% when zinc stearate is contained, and the content of zinc oxide is 0.5%-20%, preferably 1%-20% when zinc oxide is contained. This preferred solution is more conducive to the uniform distribution and stability of bubbles during the foaming process, and ensures the mechanical properties of the foaming material.

[0044] Further preferably, the filler includes calcium powder and / or talcum powder.

[0045] Further preferably, in raw material A, the cross-linking agent includes dicumyl peroxide and / or azodicarbonamide.

[0046] In some preferred embodiments of the present invention, raw material A further contains a second graphene, and the mass dosage of the second graphene is 1%-5% of the total mass of other components except the second graphene in raw material A, which is more conducive to improving the support and elasticity of material C.

[0047] In some preferred embodiments of the present invention, the process of kneading raw material A includes: kneading ethylene-vinyl acetate copolymer, filler, and the second graphene for the first time, and then putting in blowing agent, crosslinking agent, and blowing accelerator for the second kneading; wherein, the first kneading time is 3-15 min, the second kneading time is 1-8 min, and the temperatures of the first kneading and the second kneading are independently in the range of 110°C - 170°C, preferably 110°C - 165°C. This preferred scheme is more conducive to improving the mixing uniformity and foaming stability of each component during the foaming process.

[0048] In the present invention, other necessary compounds, additives, etc. can be added to raw material A according to actual applications such as high-elastic shoe soles and shock-absorbing materials. In some preferred embodiments of the present invention, based on the weight percentage content of raw material A, raw material A further contains 5%-20% of polyolefin elastomer, 3%-15% of thermoplastic elastomer, and 0.1%-2% of additives. The polyolefin elastomer is such as POE.

[0049] Further preferably, the thermoplastic elastomer is selected from at least one of ethylene-methyl acrylate copolymer, styrene-ethylene-butene-styrene copolymer (SEBS), styrene-butene-styrene copolymer (SBS), and thermoplastic polyurethane (TPU). More preferably, the thermoplastic elastomer includes ethylene-methyl acrylate copolymer, and based on the weight percentage content of raw material A, the mass content of ethylene-methyl acrylate copolymer is 1%-10%. Adding thermoplastic elastomer to raw material A of the present invention has elasticity similar to rubber and can be enhanced in elasticity and recovery performance by heating and melting, while maintaining the softness of EVA material; preferably, ethylene-methyl acrylate copolymer is also added in combination. It is a copolymer containing polar groups and can play a bridging role between polar and non-polar materials, improving the compatibility of materials. This is helpful for different components in the composite foaming material (such as ethylene-methyl acrylate copolymer and filler, etc.) to improve their dispersion uniformity, prevent material separation, and at the same time can better combine with other polar materials (such as fillers or additives), thereby improving the bonding performance of materials, and more conducive to providing excellent flexibility and elasticity, and enhancing the toughness and impact resistance of the foaming material.

[0050] Further preferably, the additive is selected from at least one of flow aid and active aid.

[0051] In some preferred embodiments of the present invention, the process of kneading raw material A includes: first kneading ethylene-vinyl acetate copolymer, polyolefin elastomer, thermoplastic elastomer, filler, and additive, and then adding blowing agent, crosslinking agent, and blowing accelerator for second kneading. Among them, the first kneading time is 3-15 min, the second kneading time is 1-8 min, and the temperatures of the first kneading and the second kneading are independently within the range of 110°C - 160°C, preferably 110°C - 160°C. This preferred solution is more conducive to further improving the elastic properties of the foamed material while ensuring uniform dispersion and stable foaming.

[0052] In some preferred embodiments of the present invention, the conditions for open milling include: the open milling temperature is 80-100°C, and the open milling time is 7-10 min; the conditions for the first vulcanization include: the vulcanization temperature is 165°C - 185°C, and the vulcanization time is 20-25 min. This preferred solution is more conducive to the uniform formation of bubbles between materials C.

[0053] In the present invention, other steps can also be carried out according to the shape of the required foamed material. In some preferred embodiments of the present invention, secondary vulcanization is carried out after the first vulcanization. The conditions for the secondary vulcanization include: the temperature is 150-160°C, and the time is 5-10 min. This preferred solution is more conducive to forming a foamed material application product with a specific shape having a microporous structure.

[0054] The embodiments of the present invention are described in detail below. They are exemplary and are only used to explain the present invention, and should not be construed as a limitation to the present invention. All raw materials in the examples are obtained through commercial purchase, and the sources of the same raw materials are the same.

[0055] Example 1 High-elastic shoe sole: 1. Based on the weight percentage of each component contained in raw material A of this step, put 60.7% of EVA7470M (ethylene-vinyl acetate copolymer, Formosa Plastics EVA), 14.5% of POE (Dow POE ENGAGE 8003 from the United States), 4.88% of 514D (specifically ethylene-methacrylic acid copolymer, purchased from DuPont), 8.5% of SEBS (styrene-ethylene-butene-styrene copolymer, purchased from Shanghai BET Chemical Co., Ltd.), 4.24% of ultrafine talc powder (purchased from Dongguan Jinxin Powder Technology Co., Ltd., model GF-1250), 0.7% of flow aid (purchased from Lanxess Group, model A-28E) into a kneader and knead for 10 min, then put 4.1% of blowing agent (purchased from Jinjiang Jiaqi Plastic Technology Co., Ltd., model AC-6000H); 0.12% of DCP (odorless crosslinking agent, dicumyl peroxide); 0.56% of light zinc stearate (purchased from Dongguan Haili Holdings Group Co., Ltd.); 0.3% of stearic acid; 1.4% of zinc oxide (purchased from Dongguan Haili Holdings Group Co., Ltd.), and continue to knead for 5 min. The kneading temperature is 160°C for both times.

[0056] 2. Take out the kneaded material and put it into an open mill for further open milling. The open milling time is 8 min and the open milling temperature is 90°C. Obtain a sheet material (i.e., material C) with uniform size and thickness of 4 mm through a sheet cutter.

[0057] 3. Take some sheet materials and coat graphene pore-forming materials (i.e., raw material B) on the upper and lower surfaces of one sheet material at the same interval respectively. Put the coated sheet material on the upper and lower sides respectively into two other uncoated sheet materials (i.e., a total of three layers, and the middle layer sheet material is coated with raw material B on both sides), and put them together into the mold of a vulcanizer for primary vulcanization. The vulcanization temperature is 175°C and the vulcanization time is 22 min. Finally, obtain a material with uniform pores in the middle. The composition of raw material B is: based on the mass percentage of each component contained in raw material B, 30% of graphene, 8% of polyethylene glycol, 3% of polyvinylpyrrolidone, 0.5% of ethylene glycol, 7% of sodium carboxymethylcellulose, 4% of ammonia water, and the balance of water. And the total coated area of raw material B accounts for 30% of the surface area of material C. The distance between adjacent coated raw material B in the X-axis and Y-axis directions is 10 mm. The coated thickness of raw material B is 500 μm, and the ratio of the coated thickness of raw material B to the thickness of adjacent material C is 0.125:1.

[0058] 4. Then cut the obtained material and put it into a sole mold for secondary vulcanization to obtain the required sole. The secondary vulcanization temperature is 155°C and the time is 8 min.

[0059] The electron micrograph of the sole material is as Figure 1 and Figure 2As shown, it can be seen that micropores are present at the position where raw material B is coated. The size of the micropores is length (3 - 4 mm) × width (1 - 2 mm). On the same foamed material obtained, the average size of multiple micropores contained is 3.5 mm × 1.5 mm.

[0060] Example 2 Shock-absorbing material: The composition of raw material A is as follows: based on the weight percentage of each component contained in raw material A, EVA7470M (the specific source is the same as that in Example 1): 70.2%; light calcium powder (calcium carbonate, commercially purchased): 9.4%; foaming agent (purchased from Jiangsu Sopu (Group) Co., Ltd., model DN6): 1.35%; DCP (dicumyl peroxide, also known as vulcanizing agent DCP): 0.52%; stearic acid 0.73%; zinc oxide 15.2%, and the mass of graphene is 2.6%.

[0061] Process flow: First, put EVA7470M, light calcium powder, and graphene into a mixer and mix for 7 min. Then put in 3300 g of foaming agent (DN6), DCP, stearic acid, and zinc oxide, and continue to mix for 3 min. The mixing temperature is 165°C for all.

[0062] Second, take out the mixed material and put it into an open mill for further open milling for 8 min at a temperature of 90°C. Obtain a sheet with uniform size and thickness of 4 mm through a sheet cutter.

[0063] Third, take some sheets and coat graphene pore-forming material (i.e., raw material B, whose composition is the same as that of raw material B in Example 1) on the upper and lower surfaces of one sheet at the same interval. Put the coated sheet on the upper and lower sides respectively into two other uncoated sheets (i.e., a total of three layers, with the middle layer sheet coated with raw material B on both sides), and put them together into the mold of a vulcanizer for vulcanization. The vulcanization temperature is 175°C and the vulcanization time is 22 min. Finally, obtain an EVA shock-absorbing material with uniform pores in the middle.

[0064] Example 3 Carry out with reference to Example 1, the difference is that the total coated area of raw material B accounts for 20% of the surface area of material C. After the same test, the obtained elastic foamed material has micropores, and the average size of the micropores is 2.5 mm × 1 mm.

[0065] Example 4 Carry out with reference to Example 1, the difference is that the distance between adjacent coated raw material Bs is adjusted to 5 mm in the X-axis direction of material C; and the distance between adjacent coated raw material Bs is adjusted to 5 mm in the Y-axis direction of material C.

[0066] Example 5 Performed with reference to Example 1, except that the coating thickness of raw material B was adjusted to 1000 μm, such that the ratio of the coating thickness to the thickness of adjacent material C was 0.25:1. After the same tests, the resulting elastic foamed material had micropores with an average size of approximately 3.5 × 2.5 mm.

[0067] Example 6 Performed with reference to Example 1, except that no polyolefin elastomer POE was added to raw material A.

[0068] Example 7 Performed with reference to Example 1, except that no thermoplastic elastomers (i.e., 514D and SEBS) were added to raw material A.

[0069] Example 8 Performed with reference to Example 2, except that no graphene was added to raw material A.

[0070] Comparative Example 1 Performed with reference to Example 1, except that the graphene in raw material B was introduced as a component in raw material A, i.e., no graphene was added to raw material B.

[0071] Comparative Example 2 Performed with reference to Example 1, except that the raw materials were added in a different manner. Specifically, raw materials A and B were mixed together, followed by kneading, open milling, and vulcanization (each process condition corresponded to Example 1).

[0072] Comparative Example 3 Performed with reference to Example 1, except that no polyethylene glycol was added to raw material B.

[0073] Comparative Example 4 Performed with reference to Example 1, except that no polyvinylpyrrolidone was added to raw material B.

[0074] Comparative Example 5 Performed with reference to Example 1, except that no ammonia water was added to raw material B.

[0075] Comparative Example 6 Performed with reference to Example 1, except that no sodium carboxymethylcellulose was added to raw material B.

[0076] Test Example The elastic foaming materials obtained from the above-mentioned examples and comparative examples were subjected to performance tests, and the results are shown in Table 1. The test standards for each performance index are as follows: 1) The rebound elasticity was tested in accordance with ISO 4462:2017; 2) The density was tested in accordance with the SATRATM134 standard; 3) The tear resistance was tested in accordance with ISO 34-1:2022; 4) The tensile property was tested in accordance with SATRATM137; 5) The hardness was tested in accordance with SATRA TM205. In addition, the test method for the buffering performance was as follows: A raw egg was placed 1 m above the surface of the corresponding target highly elastic product, and then released to let the egg fall vertically onto the surface of the target highly elastic product. After the egg bounced back, the height at which the egg bounced back without breaking was recorded. The height of the egg's rebound is shown in Table 1.

[0077] Table 1

[0078] From the above results, it can be seen that compared with the comparative examples, by adopting the embodiment scheme of the present invention, the elastic foaming material of the present invention has better rebound performance, can effectively improve the elasticity and buffering performance of the foaming material, and at the same time further reduce the density, which is beneficial to obtaining a foaming material with high elasticity, high buffering performance and lighter weight, and further broadening the application scenarios of the foaming material.

[0079] Furthermore, according to Examples 1 and 3-7, it can be seen that by adopting the preferred foaming material scheme of the present invention, it is more conducive to obtaining higher elasticity, buffering performance and tear resistance, and further improving the physical properties of the foaming material.

[0080] Furthermore, according to Examples 2 and 8, it can be seen that by adopting the preferred foaming material scheme of the present invention, it is more conducive to further reducing the density of the foaming material and making the foaming material lighter.

[0081] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. An elastic foam material, characterized in that: The method is to stack at least two layers of material C, and coat raw material B between at least two layers of material C, and then perform a vulcanization, wherein material C is obtained by mixing and kneading raw material A; Wherein, based on the weight percentage of each component contained in raw material A, raw material A contains 50%-75% of ethylene-vinyl acetate copolymer, 1%-10% of foaming agent, and 0.01%-3% of cross-linking agent; Calculated by weight percentage of each component contained in raw material B, raw material B includes 20%-40% of the first graphene, 8%-10% of polyethylene glycol, 2%-5% of polyvinyl pyrrolidone, 0.5%-1.5% of ethylene glycol, 6%-10% of sodium carboxymethyl cellulose, 3%-5% of aqueous ammonia, and water.

2. The elastic foam material according to claim 1, characterized in that: The total coating area of ​​material B accounts for 20%-80% of the surface area of ​​material C; and / or, In the X-axis direction of the material C, the distance between adjacent coated raw materials B is 1-50 mm; in the Y-axis direction of the material C, the distance between adjacent coated raw materials B is 1-50 mm.

3. The elastic foam material according to claim 1, characterized in that: The elastic foam material has micropores at the position where the raw material B is coated, and the size of the micropores is 0.1-10 mm.

4. The elastic foam material according to claim 1 or 3, characterized in that: The ratio of the coating thickness of the raw material B to the thickness of the adjacent material C is 0.001-0.5:1, and / or the coating thickness of the raw material B is 1-1200 μm.

5. The elastic foam material according to claim 1, characterized in that: Calculated by weight percentage of each component contained in raw material A, raw material A also contains 0.5%-23% of a foaming promoter and 3%-20% of a filler; The foaming promoter includes at least one of stearic acid, zinc stearate and zinc oxide. Based on the weight percentage of the corresponding components contained in raw material A, the content of stearic acid is 0.1%-2% when stearic acid is contained, the content of zinc stearate is 0.1%-2% when zinc stearate is contained, and the content of zinc oxide is 0.5%-20% when zinc oxide is contained; The filler includes calcium powder and / or talcum powder; In the raw material A, the cross-linking agent includes dicumyl peroxide and / or azodicarbonamide.

6. The elastic foam material according to claim 5, characterized in that: Raw material A also contains a second graphene, and the mass amount of the second graphene is 1%-5% of the total mass of other components in raw material A except the second graphene.

7. The elastic foam material according to claim 6, characterized in that: The process of kneading the raw material A includes: kneading the ethylene-vinyl acetate copolymer, the filler, and the second graphene once, and then adding the foaming agent, the cross-linking agent, and the foaming promoter for secondary kneading; wherein the first kneading time is 3-15 minutes, the second kneading time is 1-8 minutes, and the temperatures of the first kneading and the second kneading are independently between 110°C and 170°C.

8. The elastic foam material according to claim 5, characterized in that: Calculated by weight percentage of raw material A, raw material A also contains 5%-20% of polyolefin elastomer, 3%-15% of thermoplastic elastomer, and 0%-2% of additives.

9. The elastic foam material according to claim 8, characterized in that: The process of banburying the raw material A comprises: first banburying the ethylene-vinyl acetate copolymer, the polyolefin elastomer, the thermoplastic elastomer, the filler and the additive, and then adding the foaming agent, the cross-linking agent and the foaming promoter for second banburying, wherein the first banburying time is 3-15 minutes, the second banburying time is 1-8 minutes, and the temperatures of the first banburying and the second banburying are independently between 110° C. and 160° C.; and / or, The thermoplastic elastomer is selected from at least one of ethylene-methacrylic acid copolymer, styrene-ethylene-butylene-styrene copolymer, styrene-butylene-styrene copolymer and thermoplastic polyurethane, and the additive is selected from at least one of flow aid and active additive.

10. The elastic foam material according to claim 1, characterized in that: The conditions for the open-rolling include: the open-rolling temperature is 80-100°C, and the open-rolling time is 7-10 minutes; the conditions for the primary vulcanization include: the vulcanization temperature is 165°C-185°C, and the vulcanization time is 20-25 minutes; And / or, secondary vulcanization is performed after the vulcanization, and the conditions of the secondary vulcanization include: temperature of 150-160° C. and time of 5-10 min.

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