Preparation method of light nylon chemical foaming material

Abstract

The invention discloses a preparation method of a light nylon chemical foaming material, which comprises the following steps: preparing modified long-chain nylon: mixing 40-60 parts by mass of long-chain nylon, 40-60 parts by mass of ethylene-vinyl acetate copolymer with 25-40 weight percent of vinyl acetate, 2-5 parts by mass of first toughening agent and 0.5-1 part by mass of lubricating agent, carrying out shearing and blending treatment to obtain modified long-chain nylon; the preparation method of the light nylon chemical foaming material comprises the following steps: preparing the light nylon chemical foaming material from 20-40 parts by mass of modified long-chain nylon, 30-40 parts by mass of ethylene-vinyl acetate copolymer with 20-30 weight percent of vinyl acetate, 20-30 parts by mass of polyolefin elastomer, 5-10 parts by mass of ethylene propylene diene monomer, 7-10 parts by mass of wear-resistant agent and 1-2 parts by mass of nucleating agent; 2-3 parts by mass of an auxiliary agent, 0.5-1 part by mass of a bridging agent, 0.5-1 part by mass of a second toughening agent and 5-7 parts by mass of a foaming agent are mixed uniformly and then subjected to mold pressing and chemical foaming, and the light nylon chemical foaming material is obtained. Wherein the first toughening agent and the second toughening agent are both maleic anhydride grafted copolymers. The light nylon chemical foaming material can be prepared by the method.

Description

Technical Field

[0001] The invention relates to the technical field of nylon chemical foaming materials, and in particular to a preparation method of a lightweight nylon chemical foaming material. Background Art

[0002] Long-chain nylon (LCN), as an important high-performance polymer, has attracted much attention in the field of materials science due to the excellent mechanical strength and rigidity imparted by its molecular structure. However, the widespread application of long-chain nylon, especially in the field of high-performance foam materials, has long faced many challenges. In the existing technology, unmodified long-chain nylon generally exhibits high melting points and poor melt fluidity. These characteristics make it difficult to directly process it through conventional chemical foaming processes, and when blended with other commonly used foaming matrices (such as polyolefin materials), it is prone to problems such as poor compatibility and uneven dispersion. Summary of the Invention

[0003] The purpose of the present invention is to overcome the above-mentioned defects or problems existing in the background technology and provide a method for preparing a lightweight nylon chemical foaming material, which can prepare a lightweight nylon chemical foaming material.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] Technical Solution 1: A method for preparing a lightweight nylon chemical foaming material, comprising the following steps: preparing modified long-chain nylon: shearing and blending 40-60 parts by mass of long-chain nylon, 40-60 parts by mass of ethylene-vinyl acetate copolymer with a vinyl acetate content of 25-40 weight percent, 2-5 parts by mass of a first toughening agent, and 0.5-1 parts by mass of a lubricant to obtain the modified long-chain nylon; preparing lightweight nylon chemical foaming material: mixing 20-40 parts by mass of the modified long-chain nylon, 30-40 parts by mass of acetic acid, The lightweight nylon chemical foaming material is obtained by uniformly mixing an ethylene-vinyl acetate copolymer with a vinyl ester content of 20-30 weight percent, 20-30 weight parts of a polyolefin elastomer, 5-10 weight parts of EPDM rubber, 7-10 weight parts of an anti-wear agent, 1-2 weight parts of a nucleating agent, 2-3 weight parts of an auxiliary agent, 0.5-1 weight part of a bridging agent, 0.5-1 weight part of a second toughening agent, and 5-7 weight parts of a foaming agent, followed by molding and chemical foaming. The first toughening agent and the second toughening agent are both maleic anhydride graft copolymers.

[0006] Technical solution 2 based on technical solution 1: the first toughening agent is a maleic anhydride grafted polyolefin elastomer.

[0007] Technical solution three based on technical solution two: the maleic anhydride grafting rate of the maleic anhydride grafted polyolefin elastomer is 0.5% to 2.0% by weight.

[0008] Technical solution 4 based on technical solution 1: the second toughening agent is ethylene-maleic anhydride copolymer.

[0009] Technical solution five based on technical solution one: the polyolefin elastomer in the lightweight nylon chemical foaming material is ethylene-octene copolymer.

[0010] Technical Solution 6 based on Technical Solution 1: The nucleating agent in the lightweight nylon chemical foaming material is talcum powder, the foaming agent is an azodicarbonamide-type high-temperature foaming agent, and the bridging agent is a peroxide-type bridging agent.

[0011] Technical Solution 7 based on Technical Solution 1: The lubricant in the modified long-chain nylon is stearic acid.

[0012] Technical Solution 8 based on Technical Solution 1: The additives in the lightweight nylon chemical foaming material include 0.3-0.5 parts by mass of stearic acid, 0.5-1 parts by mass of zinc stearate and 1-2 parts by mass of zinc oxide.

[0013] Technical Solution 9 based on Technical Solution 1: The process parameters for preparing modified long-chain nylon are: shear and blending temperature is 160°C to 175°C.

[0014] Technical Solution 10 based on Technical Solution 1: The process parameters for preparing lightweight nylon chemical foaming materials are: mixing temperature of 110°C to 120°C, molding temperature of 170°C to 180°C, molding time of 520s to 580s, initial foaming ratio of 200% to 210%, and compression ratio of 140% to 150%.

[0015] From the above description of the present invention, it can be seen that compared with the prior art, the present invention has the following beneficial effects:

[0016] Technical Solution 1 provides a method for preparing a lightweight nylon chemical foam material, which achieves significant optimization of the material's comprehensive performance through a two-stage technical path.

[0017] The first stage involves the preparation of modified long-chain nylon. Here, long-chain nylon, ethylene-vinyl acetate copolymer (EVA) with a specific vinyl acetate content, a first toughening agent (maleic anhydride grafted copolymer), and a lubricant are treated under defined shear and blending conditions. Long-chain nylon possesses excellent mechanical potential, but its high melting point and poor melt fluidity limit its direct application in foam materials. The introduction of ethylene-vinyl acetate copolymer, leveraging the polarity of the vinyl acetate units in its molecules, initially improves its physical compatibility with long-chain nylon, promoting interpenetration and dispersion between the two in the molten state. More crucially, the maleic anhydride grafted copolymer, the first toughening agent, possesses maleic anhydride functional groups that can chemically graft onto the amino groups at the ends of the long-chain nylon chains. This chemical bonding creates a strong chemical bridge between the long-chain nylon and the polyolefin backbone of the toughening agent, significantly enhancing interfacial bonding, far exceeding that achieved through simple physical blending. The lubricant assists in the smooth progress of the entire melt blending process. Through the synergistic effect between the above components, especially the dual mechanism of physical compatibilization of EVA and chemical grafting of the first toughening agent, the processing performance of long-chain nylon is significantly improved, its melting temperature and melt viscosity are effectively reduced, and the melt index is increased. This modification step overcomes the technical prejudice that long-chain nylon is difficult to process, transforming it into an active material that can be uniformly mixed with other low-softening point components (such as EVA) in the subsequent foaming system within a similar processing window, laying the foundation for the preparation of high-performance foaming materials.

[0018] The second stage is the preparation of lightweight nylon chemical foaming materials. In this stage, the modified long-chain nylon prepared in the previous step is mixed evenly with ethylene-vinyl acetate copolymer with a specific vinyl acetate content, polyolefin elastomer, EPDM rubber, wear-resistant agent, nucleating agent, additive system containing zinc oxide, stearic acid and zinc stearate, bridging agent, second toughening agent (also maleic anhydride grafted copolymer) and foaming agent, and then molded chemical foaming is carried out. In this complex multi-component system, the various technical means show precise synergy. Due to its pre-acquired good dispersibility and interfacial compatibility, the modified long-chain nylon can form an effective reinforcing skeleton in the foaming matrix, providing key rigidity and toughness support for the final lightweight material. EVA as the foaming matrix, together with polyolefin elastomer and EPDM rubber, construct the material's flexible and highly elastic matrix. Notably, the reintroduction of a secondary toughening agent into the formulation further strengthens the interfacial bonding between the different polymer phases in a system already comprising modified long-chain nylon, EVA, and polyolefin elastomers through its maleic anhydride functional groups. This not only physically increases the volume but also potentially forms chemical bonds or strong physical entanglements at the interface, thereby building a more stable and dense three-dimensional network structure. This strong interfacial bonding throughout the material effectively overcomes the technical bias against interfacial fragility in traditional nylon / polyolefin blends and significantly improves the material's delamination tear strength and overall structural stability. The addition of a nucleating agent ensures the formation of a uniform and dense cellular structure during the foaming process, which is the physical foundation for achieving ultra-lightweight materials. The additive system (zinc oxide, stearic acid, zinc stearate) and the bridging agent work synergistically to induce thorough and uniform chemical crosslinking of the polymer chains under high-temperature molding, forming a stable three-dimensional network that imparts the material with excellent elastic recovery, compression set resistance, and dimensional stability. Under specific process conditions, the foaming agent decomposes to produce gas, which expands the material to form a porous structure.

[0019] In summary, this technical solution achieves this by initially synergizing the chemical and physical properties of long-chain nylon, then incorporating it into a carefully designed foaming formula. This, along with a specific foaming process, allows for a synergistic and interconnected process of components and steps, ultimately yielding a foam material that combines ultra-lightweight, high resilience, excellent mechanical strength, and superior durability. This integrated approach not only effectively leverages the inherent advantages of long-chain nylon, but also overcomes its application limitations and the technical challenges inherent in achieving a balanced performance profile in traditional foam materials.

[0020] In Technical Solution 2, the first toughening agent is further defined as a maleic anhydride grafted polyolefin elastomer. This definition clarifies the chemical structure characteristics of the toughening agent used in the long-chain nylon modification stage. The maleic anhydride group, as a reactive functional group, can undergo a chemical grafting reaction with the amino group at the end of the long-chain nylon molecular chain, forming a chemical bond between the nylon phase and the polyolefin elastomer phase. Compared with simple physical mixing, this chemical grafting effect can more significantly and stably improve the interfacial compatibility and bonding strength between the two phases. The polyolefin elastomer skeleton itself gives the material good toughness. Therefore, using maleic anhydride grafted polyolefin elastomer as the first toughening agent can more effectively "activate" the long-chain nylon, reduce its processing difficulty, and improve its dispersion uniformity and interfacial stability in the subsequent blending and foaming process, laying a solid foundation for improving the overall performance of the final foamed material.

[0021] In Technical Solution 3, the maleic anhydride grafting rate of the maleic anhydride grafted polyolefin elastomer is limited to the range of 0.5% to 2.0% (weight percentage). This grafting rate range is the key to achieving effective modification and maintaining a balance between the processing performance of the material. If the maleic anhydride grafting rate is lower than 0.5%, the number of reactive functional groups is insufficient, the grafting reaction with the long-chain nylon is insufficient, and the effect of improving the compatibility and interfacial strength is limited. On the contrary, if the grafting rate is higher than 2.0%, too many maleic anhydride groups may cause excessive cross-linking of the material or an abnormal increase in viscosity during processing, which is not conducive to uniform mixing and subsequent processing, and may also affect certain physical properties of the final product. Therefore, controlling the maleic anhydride grafting rate within the specific range of 0.5% to 2.0% can ensure sufficient and moderate chemical grafting reaction with long-chain nylon, thereby most effectively improving the chemical bond strength, synergistically reducing the system softening point, and improving the overall performance of the material. At the same time, it avoids the negative effects that may be caused by improper grafting rate, so that the modification effect and material performance reach an optimized balance point.

[0022] In technical solution four, the second toughening agent is further defined as ethylene-maleic anhydride copolymer. This copolymer contains a high concentration of maleic anhydride functional groups in its molecular chain. In the final foaming formula system containing various polymers such as modified long-chain nylon, ethylene-vinyl acetate copolymer, and polyolefin elastomer, the introduction of ethylene-maleic anhydride copolymer can strongly interact with the interfaces of different polymer phases in the system through its abundant maleic anhydride groups. These effects include chemical reactions with active groups on certain polymer chains or the formation of strong polar adsorption, thereby significantly enhancing the interfacial adhesion between different polymer phases at the microscopic level. In addition, the second toughening agent is not only a physically dispersed toughening phase, but can also serve as a reactive or highly interactive auxiliary agent, deeply involved in the construction of the polymer network, helping to form a tighter and stronger interface transition zone or overall network structure. This enhanced interfacial bonding and network structure directly and effectively improves the layered tear strength of the final foamed material and the bonding adhesion between different material layers, playing an important role in enhancing the overall structural stability and durability of the foamed material.

[0023] In technical solution five, the polyolefin elastomer in the lightweight nylon chemical foaming material is defined as ethylene-octene copolymer. As a high-performance polyolefin elastomer, ethylene-octene copolymer is famous for its excellent low-temperature toughness, good rebound performance and good compatibility with other polyolefin materials such as ethylene-vinyl acetate copolymer. The ethylene-octene copolymer is selected in the foaming material formula of the present invention, which can synergize with the main components such as ethylene-vinyl acetate copolymer and modified long-chain nylon to effectively improve the overall rebound performance, flexibility and impact resistance of the final foaming material. At the same time, the selection of ethylene-octene copolymer with good processing compatibility with other main polymers in the system is also conducive to the uniform dispersion of each component during the mixing process, thereby ensuring the uniformity of the pore structure of the final foamed product and the stability of its performance.

[0024] Technical Solution 6 defines the specific types of nucleating agents, foaming agents, and bridging agents. Talc is used as the nucleating agent. Its fine particles act as heterogeneous nucleation sites in the polymer melt, inducing the formation of numerous, uniform, and fine cells, which is crucial for achieving low material density and maintaining excellent mechanical properties. Azodicarbonamide is used as the foaming agent. Its high decomposition temperature ensures stability during the relatively low mixing temperature, preventing premature decomposition. At higher molding temperatures, it decomposes rapidly and uniformly to produce sufficient gas, which is key to achieving ultra-lightweight materials. A peroxide is used as the bridging agent. Its decomposition at the high molding temperatures produces active free radicals, which initiate chemical crosslinking reactions between polymer chains, forming a stable three-dimensional network structure. This network structure is the fundamental guarantee for the foamed material's excellent elasticity, compression set resistance, heat resistance, and dimensional stability. These three additives work synergistically during the foaming process, ensuring controllable foaming, uniform cell structure, and achieving excellent physical and chemical properties in the final product.

[0025] Technical Solution 7 specifies that the lubricant used in the preparation of modified long-chain nylon is stearic acid. As a commonly used external lubricant, stearic acid can effectively reduce friction between the molten material and the metal surfaces of processing equipment during the high-temperature shearing and blending modification of long-chain nylon with components such as ethylene-vinyl acetate copolymer, preventing material adhesion to the wall, thereby improving material fluidity and dispersibility and reducing processing energy consumption. Furthermore, the use of stearic acid helps ensure the stability and continuity of the modification process, avoiding localized overheating or uneven shearing caused by excessive friction or material viscosity, thereby ensuring the uniformity and stability of the quality of the modified long-chain nylon product.

[0026] Technical Solution 8 specifies that the additives in lightweight nylon chemical foaming materials include specific weight percentages of stearic acid, zinc stearate, and zinc oxide. These three substances together form a "zinc salt activation system," which plays a key synergistic role in the cross-linking foaming system using peroxide as a bridging agent. Zinc oxide, the primary activator, significantly improves the decomposition and cross-linking efficiency of the peroxide bridging agent, promoting the formation of a more complete and uniform cross-linked network between polymer chains. In this system, stearic acid not only aids dispersion and provides lubricity, but also reacts with zinc oxide to form zinc stearate, which helps regulate the cross-linking reaction rate. Zinc stearate, as a reaction product or a direct additive, not only synergistically activates the cross-linking reaction but also may regulate the decomposition behavior of the foaming agent, contributing to a homogenized cell structure. The precise proportions and synergistic effects of these three additives ensure efficient, uniform, and controllable cross-linking, resulting in the final foamed material with ideal elasticity, tensile strength, compression set resistance, and overall mechanical properties.

[0027] In Technical Solution Nine, the shear and blending temperature for preparing modified long-chain nylon is limited to 160°C to 175°C. The selection of this temperature range is crucial for achieving effective modification of long-chain nylon. First, this temperature range is higher than the melting or softening temperature of the main components, long-chain nylon (which has been plasticized by EVA to a certain extent) and ethylene-vinyl acetate copolymer, which can ensure that they are fully melted and reduce the melt viscosity, thereby achieving uniform mixing and dispersion of the components under high shear. Secondly, this temperature range provides the necessary activation energy for the chemical grafting reaction between the maleic anhydride functional groups on the first toughening agent (maleic anhydride grafted polyolefin elastomer) and the terminal amino groups of the long-chain nylon, which is conducive to the effective conduct of the grafting reaction. At the same time, the setting of the upper temperature limit also takes into account the avoidance of significant thermal degradation that may occur if the polymer material stays at this temperature for a long time. Therefore, shearing and blending treatments within the temperature range of 160°C to 175°C are the optimal choice to strike a balance between ensuring sufficient melt mixing, effective chemical grafting, and avoiding material degradation, thereby enabling the stable preparation of modified long-chain nylon with improved melt fluidity and good dispersibility.

[0028] In Technical Solution 10, a series of key process parameters for the preparation of lightweight nylon chemical foaming materials are defined, including mixing temperature, molding temperature, molding time, initial foaming ratio and compression ratio. The coordinated control of these parameters precisely regulates the final structure and properties of the foamed material. The mixing temperature is set at 110°C to 120°C, which ensures that all material components can be evenly mixed to form a homogeneous blend. At the same time, this temperature is lower than the significant decomposition temperature of the high-temperature foaming agent and the peroxide bridging agent, preventing them from being activated prematurely during the mixing stage. Increasing the molding temperature to 170°C to 180°C can effectively trigger the decomposition and gas production of the high-temperature foaming agent and the cross-linking reaction of the peroxide bridging agent. Adequate molding time (520s to 580s) ensures that the foaming and cross-linking reactions are fully carried out, so that the pore structure is stabilized and the material properties are fully developed. A preform expansion ratio of 200% to 210% is crucial for achieving the extremely low density of the final product. The increased melt strength achieved by the introduction of modified long-chain nylon ensures that the integrity and uniformity of the preform are maintained even at this high expansion ratio. An appropriate compression ratio (140% to 150%) helps control cell growth during the molding process, as well as the density and surface quality of the final product. Through precise control and effective coordination of these process parameters, the present invention consistently produces lightweight nylon chemical foam materials with a uniform and fine cell structure, extremely low density, high resilience, excellent mechanical properties, and dimensional stability. DETAILED DESCRIPTION

[0029] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are preferred embodiments of the present invention and should not be considered as excluding other embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0030] In the claims and description of the present invention, unless otherwise clearly defined, the use of terms such as "first", "second" or "third" is for distinguishing different objects rather than for describing a specific order.

[0031] In the claims and description of the present invention, if the terms "include", "have" and their variations are used, they are intended to mean "including but not limited to".

[0032] The present invention relates to a method for preparing a lightweight nylon chemical foam material, which comprises the following steps:

[0033] Preparation of modified long-chain nylon: 40-60 parts by weight of long-chain nylon, 40-60 parts by weight of ethylene-vinyl acetate copolymer having a vinyl acetate content of 25-40 weight percent, 2-5 parts by weight of a first toughening agent, and 0.5-1 part by weight of a lubricant, subjected to shearing and blending treatment to obtain the modified long-chain nylon;

[0034] Preparation of a lightweight nylon chemical foaming material: 20-40 parts by mass of the modified long-chain nylon, 30-40 parts by mass of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 20-30 weight percent, 20-30 parts by mass of a polyolefin elastomer, 5-10 parts by mass of EPDM rubber, 7-10 parts by mass of an anti-wear agent, 1-2 parts by mass of a nucleating agent, 2-3 parts by mass of an auxiliary agent, 0.5-1 part by mass of a bridging agent, 0.5-1 part by mass of a second toughening agent, and 5-7 parts by mass of a foaming agent are mixed uniformly and then subjected to molding for chemical foaming to obtain the lightweight nylon chemical foaming material;

[0035] Wherein, the first toughening agent and the second toughening agent are both maleic anhydride graft copolymers.

[0036] As a preferred embodiment, the first toughening agent is a maleic anhydride grafted polyolefin elastomer. The maleic anhydride grafting rate of the maleic anhydride grafted polyolefin elastomer is 0.5% to 2.0% by weight. Specifically, those skilled in the art can select commercially available maleic anhydride grafted ethylene-octene copolymer (MAH-g-POE) or maleic anhydride grafted ethylene propylene diene monomer (MAH-g-EPDM), such as DuPont's When selecting a specific grade of maleic anhydride grafted polyolefin elastomer, those skilled in the art should ensure that its maleic anhydride grafting rate falls within the optimized range of 0.5% to 2.0% by weight to achieve sufficient grafting reaction and good material properties.

[0037] Furthermore, the second toughening agent is ethylene-maleic anhydride copolymer. Specifically, it can be Vertellus nylon special chain extender tackifier E60P.

[0038] Furthermore, the polyolefin elastomer in the light nylon chemical foaming material is ethylene-octene copolymer. Specifically, those skilled in the art can select ENGAGE TM POE 8003 or Mitsui Chemicals' TAFMER TM Other commercially available ethylene-octene copolymer grades in the series with similar physical and chemical properties (such as density, melt index, octene content).

[0039] Furthermore, the nucleating agent in the lightweight nylon chemical foaming material is talcum powder, the foaming agent is an azodicarbonamide high-temperature foaming agent, and the bridging agent is a peroxide bridging agent. Specifically, those skilled in the art should select industrial-grade fine powdered talcum powder with an average particle size generally in the range of 1-10 microns to ensure good nucleation efficiency and dispersibility. Those skilled in the art should select commercially available azodicarbonamide (ADC or AC) high-temperature foaming agents, such as the common AC-3000, AC-7000 and other brands, whose decomposition temperature is generally in the range of 195-215°C, and select the appropriate decomposition temperature and gas emission according to the specific process requirements. Those skilled in the art can select commonly used peroxide bridging agents, such as dicumyl peroxide (DCP, such as commercially available products with a purity of more than 98%), or bis-2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (such as Akzo Nobel's 101), particularly "odorless" or low-odor grades that have been treated or purified to reduce odor.

[0040] Furthermore, the lubricant in the modified long-chain nylon is stearic acid. Specifically, those skilled in the art should select commercially available industrial-grade stearic acid products, such as stearic acid of type 1801 or similar specifications that conform to GB / T 9103-2017.

[0041] Furthermore, the additives in the lightweight nylon chemical foaming material include 0.3-0.5 parts by mass of stearic acid, 0.5-1 parts by mass of zinc stearate, and 1-2 parts by mass of zinc oxide. Specifically, those skilled in the art should select commercially available industrial-grade stearic acid, industrial-grade zinc stearate (usually a product with a zinc content of 10-13%), and industrial-grade active zinc oxide (e.g., a product with a specific surface area greater than 5 m 2 / g of 99.7% pure zinc oxide prepared by indirect or direct method).

[0042] The process parameters for preparing the modified long-chain nylon are: shear and blending temperatures of 160°C to 175°C. The process parameters for preparing the lightweight nylon chemical foam material are: mixing temperature of 110°C to 120°C, molding temperature of 170°C to 180°C, molding time of 520s to 580s, initial foaming ratio of 200% to 210%, and compression ratio of 140% to 150%. Specifically, when practicing the present invention, those skilled in the art can choose long-chain nylon such as NE20067 or similar long-chain polyamides such as PA610, PA612, PA1010, PA1012, and PA1212. The VA content of the ethylene-vinyl acetate copolymer (EVA) during the modification stage is preferably 28% to 33% (by weight), and the VA content during the foaming stage is preferably 26% (by weight). A twin-screw extruder or similar high-shear mixing equipment should be used to modify long-chain nylon, and the temperature of each section of the extruder should be strictly controlled within the range of 160°C to 175°C, and the screw speed can be controlled at 200-400rpm. When preparing lightweight foamed materials, an open mill or internal mixer should be used for mixing at 110°C to 120°C to ensure that the materials are evenly mixed. Subsequently, in the compression molding stage, the mold temperature should be precisely controlled at 170°C to 180°C, the heating time should be 520s to 580s, the initial foaming ratio should be 200% to 210%, and the compression ratio should be 140% to 150% to ensure sufficient foaming and complete cross-linking, thereby obtaining a lightweight nylon chemical foam material with target properties.

[0043] To further illustrate the superiority of the method for preparing the lightweight nylon chemical foaming material involved in the present invention, the present invention provides the following examples and comparative examples.

[0044] Unless otherwise specified, the brands and specifications of raw materials used in the examples and comparative examples are as follows: Long-chain nylon: brand NE20067. Ethylene-vinyl acetate copolymer (EVA) is used to modify long-chain nylon: the content of vinyl acetate (VA) is 30 weight percent. Ethylene-vinyl acetate copolymer (EVA) is used for foaming material: the content of vinyl acetate (VA) is 26 weight percent. First toughening agent: maleic anhydride grafted ethylene-octene copolymer (MAH-g-POE), the maleic anhydride grafting rate is 1.0 weight percent, such as DuPont's Fusabond P613 or similar products. Lubricant: stearic acid, industrial grade, in compliance with GB / T9103-2017 standard. Polyolefin elastomer (POE): ethylene-octene copolymer, brand ENGAGE TM POE 8003 (Dow Chemical) or POE8150 (Mitsui Chemicals, select one or mix according to the dosage). EPDM: Commonly available brands. Anti-wear agent: For example, Celanese Ultra-high molecular weight polyethylene (UHMWPE) powder (such as GUR 4120 powder), or other commercially available shoe wear-resistant agents with similar functions. Nucleating agent: Talc, average particle size 5 microns. Stearic acid additive: Same as lubricant. Zinc stearate additive: Industrial grade, zinc content 10-13%. Zinc oxide additive: Industrial grade, activated zinc oxide, 99.7% purity. Bridging agent: Dicumyl peroxide (DCP), odorless grade. Secondary toughening agent: Ethylene-maleic anhydride copolymer, brand E60P (Vertellus). Foaming agent: Azodicarbonamide (ADC) high-temperature foaming agent, brand AC-3000.

[0045] General process parameters for preparing modified long-chain nylon: add the components into a twin-screw extruder, set the temperatures of each section of the extruder to 160°C, 165°C, 170°C, 175°C, 175°C, and 170°C (discharge port), and the screw speed to 300 rpm, perform shearing and blending treatments, and then pelletize to obtain modified long-chain nylon.

[0046] General process parameters for preparing lightweight nylon chemical foam materials: Modified long-chain nylon and other components are mixed uniformly on an open mill at 115°C to produce a blend. The blend is placed in a mold and chemically foamed by compression molding on a flat-plate vulcanizer. The molding temperature is 175°C, the molding time is 550 seconds, the initial foaming ratio is 205%, and the compression ratio is 145%.

[0047] Example 1

[0048] Preparation of modified long-chain nylon (M-LCN-1):

[0049] The components include: 40 parts by mass of long-chain nylon (NE20067), 60 parts by mass of EVA (VA 30%), 2 parts by mass of a first toughening agent (MAH-g-POE), and 0.5 parts by mass of a lubricant (stearic acid). Modified long-chain nylon M-LCN-1 was prepared according to the above general process parameters.

[0050] Preparation of lightweight nylon chemical foaming materials:

[0051] The components include: 20 parts by mass of modified long-chain nylon (M-LCN-1), 40 parts by mass of EVA (VA 26%), 20 parts by mass of polyolefin elastomer (POE8150), 5 parts by mass of EPDM rubber, 7 parts by mass of anti-wear agent, 1 part by mass of nucleating agent (talc), additives (0.3 parts by mass of stearic acid, 0.5 parts by mass of zinc stearate, 1.2 parts by mass of zinc oxide, a total of 2.0 parts by mass), 0.5 parts by mass of bridging agent (DCP), 0.5 parts by mass of secondary toughening agent (E60P), and 5 parts by mass of foaming agent (AC-3000). A foamed material was prepared according to the above general process parameters.

[0052] Example 2

[0053] Preparation of modified long-chain nylon (M-LCN-2):

[0054] The components include: 50 parts by mass of long-chain nylon (NE20067), 50 parts by mass of EVA (VA 30%), 3.5 parts by mass of a first toughening agent (MAH-g-POE), and 0.75 parts by mass of a lubricant (stearic acid). Modified long-chain nylon M-LCN-2 was prepared according to the above general process parameters.

[0055] Preparation of lightweight nylon chemical foaming materials:

[0056] The components include: 30 parts by mass of modified long-chain nylon (M-LCN-2), 35 parts by mass of EVA (VA 26%), 25 parts by mass of polyolefin elastomer (ENGAGE POE 8003), 7.5 parts by mass of EPDM rubber, 8.5 parts by mass of anti-wear agent, 1.5 parts by mass of nucleating agent (talc), additives (0.4 parts by mass of stearic acid, 0.75 parts by mass of zinc stearate, 1.5 parts by mass of zinc oxide, a total of 2.65 parts by mass), 0.75 parts by mass of bridging agent (DCP), 0.75 parts by mass of secondary toughening agent (E60P), and 6 parts by mass of foaming agent (AC-3000). A foamed material was prepared according to the above general process parameters.

[0057] Example 3

[0058] Preparation of modified long-chain nylon (M-LCN-3):

[0059] The components include: 60 parts by mass of long-chain nylon (NE20067), 40 parts by mass of EVA (VA 30%), 5 parts by mass of a first toughening agent (MAH-g-POE), and 1.0 part by mass of a lubricant (stearic acid). Modified long-chain nylon M-LCN-3 was prepared according to the above general process parameters.

[0060] Preparation of lightweight nylon chemical foaming materials:

[0061] The components include: 40 parts by mass of modified long-chain nylon (M-LCN-3), 30 parts by mass of EVA (VA 26%), 30 parts by mass of polyolefin elastomer (ENGAGE POE 8003), 10 parts by mass of EPDM rubber, 10 parts by mass of an anti-wear agent, 2 parts by mass of a nucleating agent (talc), additives (0.5 parts by mass of stearic acid, 1.0 parts by mass of zinc stearate, 1.5 parts by mass of zinc oxide, a total of 3.0 parts by mass), 1.0 parts by mass of a bridging agent (DCP), 1.0 parts by mass of a secondary toughening agent (E60P), and 7 parts by mass of a foaming agent (AC-3000). A foamed material was prepared according to the above general process parameters.

[0062] Example 4

[0063] Preparation of modified long-chain nylon (M-LCN-4):

[0064] The components include: 50 parts by mass of long-chain nylon (NE20067), 50 parts by mass of EVA (VA 30%), 3 parts by mass of a first toughening agent (MAH-g-POE), and 0.8 parts by mass of a lubricant (stearic acid). Modified long-chain nylon M-LCN-4 was prepared according to the above general process parameters.

[0065] Preparation of lightweight nylon chemical foaming materials:

[0066] The components include: 30 parts by mass of modified long-chain nylon (M-LCN-4), 36 parts by mass of EVA (VA 26%), 26 parts by mass of polyolefin elastomer (ENGAGE POE 8003), 8 parts by mass of EPDM rubber, 8.8 parts by mass of an anti-wear agent, 1.5 parts by mass of a nucleating agent (talc), additives (0.44 parts by mass of stearic acid, 0.74 parts by mass of zinc stearate, 1.47 parts by mass of zinc oxide, a total of 2.65 parts by mass), 0.62 parts by mass of a bridging agent (DCP), 0.74 parts by mass of a secondary toughening agent (E60P), and 5.6 parts by mass of a blowing agent (AC-3000). A foamed material was prepared according to the above general process parameters.

[0067] Comparative Example 1: No modified long-chain nylon was used.

[0068] Preparation of modified long-chain nylon: No such step.

[0069] Preparation of lightweight nylon chemical foaming materials:

[0070] The components include: 30 parts by mass of unmodified long chain nylon (NE20067) (replacing M-LCN-2 in Example 2), 35 parts by mass of EVA (VA 26%), and polyolefin elastomer (ENGAGE TM POE 8003) 25 parts by mass, EPDM rubber 7.5 parts by mass, anti-wear agent 8.5 parts by mass, nucleating agent (talc) 1.5 parts by mass, additives (stearic acid 0.4 parts by mass, zinc stearate 0.75 parts by mass, zinc oxide 1.5 parts by mass, totaling 2.65 parts by mass), bridging agent (DCP) 0.75 parts by mass, second toughening agent (E60P) 0.75 parts by mass, and foaming agent (AC-3000) 6 parts by mass. The foamed material was prepared according to the above general process parameters. Due to the high melting point and poor fluidity of unmodified long-chain nylon, mixing at 115°C is expected to be difficult and the dispersion is poor.

[0071] Comparative Example 2: The first toughening agent was not used in the preparation of the modified long-chain nylon.

[0072] Preparation of modified long-chain nylon (M-LCN-C2):

[0073] The components include: 50 parts by mass of long-chain nylon (NE20067), 50 parts by mass of EVA (VA 30%), and 0.75 parts by mass of a lubricant (stearic acid) (without the first toughening agent). Modified long-chain nylon M-LCN-C2 was prepared using the general process parameters described above. Nylon and EVA are expected to have poor compatibility.

[0074] Preparation of lightweight nylon chemical foaming materials:

[0075] The components include: 30 parts by mass of modified long-chain nylon (M-LCN-C2), 35 parts by mass of EVA (VA 26%), 25 parts by mass of polyolefin elastomer (ENGAGE POE 8003), 7.5 parts by mass of EPDM rubber, 8.5 parts by mass of anti-wear agent, 1.5 parts by mass of nucleating agent (talc), additives (0.4 parts by mass of stearic acid, 0.75 parts by mass of zinc stearate, 1.5 parts by mass of zinc oxide, a total of 2.65 parts by mass), 0.75 parts by mass of bridging agent (DCP), 0.75 parts by mass of secondary toughening agent (E60P), and 6 parts by mass of foaming agent (AC-3000). A foamed material was prepared according to the above general process parameters.

[0076] Comparative Example 3: The second toughening agent was not used in the preparation of the foaming material.

[0077] Preparation of modified long-chain nylon (M-LCN-2): Same as Example 2. Its components include: 50 parts by mass of long-chain nylon (NE20067), 50 parts by mass of EVA (VA 30%), 3.5 parts by mass of a first toughening agent (MAH-g-POE), and 0.75 parts by mass of a lubricant (stearic acid).

[0078] Preparation of lightweight nylon chemical foaming materials:

[0079] The components include: 30 parts by mass of modified long-chain nylon (M-LCN-2), 35 parts by mass of EVA (VA 26%), 25 parts by mass of polyolefin elastomer (ENGAGE POE 8003), 7.5 parts by mass of EPDM rubber, 8.5 parts by mass of anti-wear agent, 1.5 parts by mass of nucleating agent (talc), additives (0.4 parts by mass of stearic acid, 0.75 parts by mass of zinc stearate, 1.5 parts by mass of zinc oxide, a total of 2.65 parts by mass), 0.75 parts by mass of bridging agent (DCP), and 6 parts by mass of foaming agent (AC-3000) (no second toughening agent is added). A foamed material was prepared according to the above general process parameters.

[0080] Comparative Example 4: The dosage of the key components exceeds the preferred range of the present invention.

[0081] Preparation of modified long-chain nylon (M-LCN-2): Same as Example 2. Its components include: 50 parts by mass of long-chain nylon (NE20067), 50 parts by mass of EVA (VA 30%), 3.5 parts by mass of a first toughening agent (MAH-g-POE), and 0.75 parts by mass of a lubricant (stearic acid).

[0082] Preparation of lightweight nylon chemical foaming materials:

[0083] The components include: modified long chain nylon (M-LCN-2) 15 parts by mass (lower than the lower limit of 20-40 parts of the claim), EVA (VA 26%) 45 parts by mass (higher than the upper limit of 30-40 parts of the claim), polyolefin elastomer (ENGAGE TM A foamed material was prepared according to the general process parameters described above, comprising 25 parts by mass of POE 8003, 7.5 parts by mass of EPDM rubber, 8.5 parts by mass of an anti-wear agent, 1.5 parts by mass of a nucleating agent (talc), 1.5 parts by mass of additives (0.4 parts by mass of stearic acid, 0.75 parts by mass of zinc stearate, and 1.5 parts by mass of zinc oxide, for a total of 2.65 parts by mass), 0.75 parts by mass of a bridging agent (DCP), 0.75 parts by mass of a secondary toughening agent (E60P), and 6 parts by mass of a blowing agent (AC-3000).

[0084] Test results

[0085] The performance of the lightweight nylon chemical foaming materials prepared in Examples 1-4 and Comparative Examples 1-4 was tested.

[0086] The test standards for various performances are as follows:

[0087] Density: GB / T 6343-2009.

[0088] Hardness (Asker C): Refer to GB / T 531.1-2008 and use Asker C hardness tester.

[0089] Rebound rate: GB / T 1681-2009.

[0090] Tensile strength: GB / T 528-2009.

[0091] Elongation at break: GB / T 528-2009.

[0092] Delamination tear strength: Test according to GB / T 529-2008 and record the delamination phenomenon and strength. Adhesion strength: GB / T 2790-1995 (simulation of interlayer adhesion).

[0093] Compression set (70°C, 22h, 25% compression): GB / T 7759.1-2015.

[0094] Thermal shrinkage (70°C, 20 min): Aging was performed according to GB / T 3512-2014 and dimensional changes were measured.

[0095] The test results are shown in Table 1.

[0096] Table 1: Test results of foaming material performance of various embodiments and comparative examples:

[0097]

[0098] From the test results in Table 1 we can see that:

[0099] The Importance of Modified Long-Chain Nylon: Compared to Comparative Example 1 (using unmodified long-chain nylon), Examples 1-4 demonstrate significant advantages in various properties, including density, rebound, tensile strength, elongation at break, delamination tear strength, adhesive strength, compression set, and thermal shrinkage. This demonstrates that the first-stage modification of long-chain nylon effectively improves its processing properties and compatibility with other components in the foaming system, laying the foundation for the preparation of high-performance, lightweight foamed materials. Comparative Example 1, due to poor dispersion and uneven foaming of the unmodified nylon, results in high density, poor mechanical properties, and poor dimensional stability.

[0100] The role of the first toughening agent in the modification: Compared with Comparative Example 2 (which did not include the first toughening agent during the modification), Example 2 exhibited lower density, higher rebound rate, better mechanical strength (tensile strength, delamination tear strength, and adhesive strength), and lower compression set. This demonstrates the key role of the first toughening agent (MAH-g-POE) in the modification of long-chain nylon. Through chemical grafting, it strengthens the interfacial bonding between the long-chain nylon and EVA, enhancing the modification effect and thus improving the overall performance of the final foamed material.

[0101] The role of the second toughening agent in foaming: Compared with Comparative Example 3 (which did not include a second toughening agent during foaming), Example 2 showed significant improvements in delamination tear strength and adhesive strength, while also showing some improvement in other properties such as rebound rate and tensile strength. This demonstrates that the second toughening agent (E60P) can further enhance the interfacial bonding between the different polymer phases in the foaming system, forming a more stable network structure, thereby significantly improving the structural stability and durability of the material, particularly its anti-delamination ability.

[0102] Reasonableness of the component dosage range: Compared with Comparative Example 4 (the dosage of key components exceeds the preferred range of the present invention, such as the dosage of modified long-chain nylon is too low and the dosage of EVA is too high), Examples 1-4 (especially Examples 2 and 4) exhibit more balanced and excellent mechanical properties (such as hardness, tensile strength) and rebound performance while maintaining low density. Although the density of Comparative Example 4 is also relatively low, the rigidity and strength of the material are reduced due to the weakening of the nylon skeleton, and the hardness is low. This shows that the dosage range of each component defined by the claims of the present invention is optimized and can synergistically achieve lightweight and high performance of the material.

[0103] Advantages of the embodiments of the present invention: Examples 1-3 demonstrate the influence trend of adjusting the amount of each component on the material properties within the scope of the claims, and all of them can obtain lightweight nylon foam materials with good comprehensive properties.

[0104] Example 4 shows excellent comprehensive performance in key indicators such as density, rebound rate, mechanical strength (tensile strength, delamination tear strength, adhesive strength), compression permanent deformation and thermal shrinkage, reaching 0.100g / cm 3 The low density and high rebound rate of 70% combined with good strength and dimensional stability verify that the technical solution of the present invention can prepare lightweight nylon chemical foaming materials with excellent performance.

[0105] The above description and embodiments are intended to explain the scope of protection of the present invention, but do not constitute a limitation thereto. Modifications, equivalent substitutions, or other improvements to the embodiments of the present invention or portions thereof that can be obtained by a person of ordinary skill in the art through logical analysis, reasoning, or limited experimentation based on the teachings of the present invention or the above embodiments, combined with common knowledge, ordinary technical knowledge in the field, and / or prior art, should all be included within the scope of protection of the present invention.

Claims

1. A method for preparing a lightweight nylon chemical foam material, characterized in that: The following steps are involved: Preparation of modified long-chain nylon: 40-60 parts by weight of long-chain nylon, 40-60 parts by weight of ethylene-vinyl acetate copolymer having a vinyl acetate content of 25-40 weight percent, 2-5 parts by weight of a first toughening agent, and 0.5-1 part by weight of a lubricant, subjected to shearing and blending treatment to obtain the modified long-chain nylon; Preparation of a lightweight nylon chemical foaming material: 20-40 parts by mass of the modified long-chain nylon, 30-40 parts by mass of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 20-30 weight percent, 20-30 parts by mass of a polyolefin elastomer, 5-10 parts by mass of EPDM rubber, 7-10 parts by mass of an anti-wear agent, 1-2 parts by mass of a nucleating agent, 2-3 parts by mass of an auxiliary agent, 0.5-1 part by mass of a bridging agent, 0.5-1 part by mass of a second toughening agent, and 5-7 parts by mass of a foaming agent are mixed uniformly and then subjected to molding for chemical foaming to obtain the lightweight nylon chemical foaming material. The first toughening agent and the second toughening agent are both maleic anhydride graft copolymers.

2. The method for preparing a lightweight nylon chemical foam material according to claim 1, wherein: The first toughening agent is maleic anhydride grafted polyolefin elastomer.

3. The method for preparing a lightweight nylon chemical foam material according to claim 2, wherein: The maleic anhydride grafted polyolefin elastomer has a maleic anhydride grafting rate of 0.5% to 2.0% by weight.

4. The method for preparing a lightweight nylon chemical foam material according to claim 1, wherein: The second toughening agent is ethylene-maleic anhydride copolymer.

5. The method for preparing a lightweight nylon chemical foam material according to claim 1, wherein: The polyolefin elastomer in the lightweight nylon chemical foaming material is ethylene-octene copolymer.

6. The method for preparing a lightweight nylon chemical foam material according to claim 1, wherein: The nucleating agent in the lightweight nylon chemical foaming material is talcum powder, the foaming agent is an azodicarbonamide-type high-temperature foaming agent, and the bridging agent is a peroxide-type bridging agent.

7. The method for preparing a lightweight nylon chemical foam material according to claim 1, wherein: The lubricant in the modified long-chain nylon is stearic acid.

8. The method for preparing a lightweight nylon chemical foam material according to claim 1, wherein: The auxiliary agents in the lightweight nylon chemical foaming material include 0.3-0.5 parts by mass of stearic acid, 0.5-1 parts by mass of zinc stearate and 1-2 parts by mass of zinc oxide.

9. The method for preparing a lightweight nylon chemical foam material according to claim 1, wherein: The process parameters for preparing the modified long-chain nylon are: shearing and blending temperature is 160°C to 175°C.

10. The method for preparing a lightweight nylon chemical foam material according to claim 1, wherein: The process parameters for preparing lightweight nylon chemical foaming material are: mixing temperature of 110°C to 120°C, molding temperature of 170°C to 180°C, molding time of 520s to 580s, initial foaming ratio of 200% to 210%, and compression ratio of 140% to 150%.

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