Lightweight insulating flame-retardant epoxy resin composite material and preparation method thereof

Abstract

The invention discloses a lightweight insulating flame-retardant epoxy resin composite material and a preparation method thereof.The preparation method comprises the steps that according to different coupling agent concentrations, treatment durations and treatment temperatures, a specific number of active groups are promoted to be formed on the surfaces of hollow glass beads, aluminum oxide hollow microspheres and montmorillonite; then, by adopting a plasma surface treatment means, more active groups are additionally introduced to the surfaces of the hollow glass beads and the montmorillonite, more sites for binding are expanded, and the surface characteristics of the hollow glass beads and the montmorillonite are further optimized. Through the method, the interface bonding efficiency between the filler and an epoxy resin matrix is powerfully enhanced, so that the mechanical property and the insulating property of the epoxy resin composite material are remarkably improved, and the hollow filler realizes light weight of epoxy resin; the aluminum oxide and the montmorillonite which is stripped and dispersed by wet ball milling of the coupling agent synergistically improve the flame retardant property, and the comprehensive characteristics of light weight, insulation and flame retardance are optimized. The method not only is simple in implementation process and convenient to operate, but also has very strong applicability in the field of industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a lightweight insulating flame-retardant epoxy resin composite material and a preparation method thereof. Background Art

[0002] In the field of materials science, polymer materials are undoubtedly an extremely important branch, which are widely interwoven in all walks of life and deeply affect people's daily production and life practices. Epoxy resin has outstanding comprehensive performance, excellent mechanical properties, superior bonding level, reliable chemical stability, significant electrical insulation performance, and extremely convenient molding and processing. For this reason, it is favored in many fields such as automobile production, power electronics technology, and aerospace engineering, and is widely used. However, epoxy resin is not flawless. Once cured, its shortcomings such as poor material toughness, low impact strength, limited flame retardant effect, and weak high temperature resistance are exposed. This makes it difficult to fully display its strength in high-temperature scenes or those high-end frontier fields that need to bear high-intensity impact loads, and its application potential is also limited.

[0003] With the rapid development of related industries and continuous technological breakthroughs, the market's expectations for the performance of epoxy resins are rising. In view of this, a series of difficult problems such as how to enhance the toughness of epoxy resins, improve impact strength, enhance high temperature resistance, stabilize insulation properties, strengthen fire resistance, and optimize sound insulation effects have naturally become the focus of current scientific research. In order to overcome these difficulties, after repeated exploration, researchers have innovatively proposed to use a variety of composite materials such as hollow microspheres, flaky montmorillonite and flame retardants to improve epoxy resins, striving to optimize the various performance indicators of epoxy resins in an all-round way, thereby expanding its application areas. Composite materials refer to the combination of two or more material components with different chemical and physical properties in a specific form, proportion and distribution method, with obvious interface separation between the components. For resin-based composites modified with hollow microspheres, lamellar montmorillonite and flame retardants, on the one hand, the dispersion state of the filler and the degree of peeling of the multi-layer stacked filler have a great influence on the mechanical properties and functionality of the composite material. Slight changes in these factors may cause performance fluctuations; on the other hand, the interfacial force between the filler and the polymer matrix determines the comprehensive performance of the composite material to a large extent. The interfacial interaction force is mainly determined by the surface structural characteristics of the material, such as surface roughness, pore structure and the number of active groups, and the chemical structure of the matrix also has an effect. In the composite material system, the interface plays a key role in connecting the matrix and the reinforcement, and is responsible for effectively transferring stress from the matrix to the reinforcement. If the interface is not well bonded, it is easy to cause interface debonding and cracking problems, weakening the overall structure of the composite material and making it unable to fully exert the mechanical properties of the reinforcement material. The interface also has the function of inhibiting crack propagation. If the interface performance is poor, the composite material may be delaminated. When the interfacial force is weak, that is, when the compatibility is poor, it is difficult for the functional filler to be evenly distributed in the polymer matrix, and the overall performance of the material will also be significantly affected. Therefore, the interface performance is the key to determining the final performance of the composite material. It should be noted that hollow microspheres, hollow alumina microspheres and flaky fillers usually have smooth surfaces and lack active groups, which results in weak interfacial bonding with epoxy resins and makes it difficult to fully exert their reinforcing, toughening and flame retardant effects. Therefore, how to improve the bonding performance of these fillers with epoxy resins has become a core challenge in the preparation of high-performance epoxy resin composites. The use of surface modification technology can increase the number of active groups on the filler surface, improve the surface roughness of hollow microspheres, flame retardants and montmorillonite, thereby strengthening the interfacial bonding, making the filler in the polymer matrix more evenly dispersed, and ultimately achieving a significant improvement in the overall performance of the composite material.

[0004] At present, in the field of materials, surface modification technology is roughly divided into two main categories: physical method and chemical method. As far as chemical modification is concerned, methods such as chemical etching and chemical surface grafting are included. Relevant research results show that once the material is treated by chemical methods, many properties of the filler, such as surface roughness and interface shear strength, will be significantly improved. However, the chemical treatment process may cause some negative situations, such as surface corrosion, causing defects in the material, and even leading to risks such as a decline in mechanical properties. In addition, a large number of chemical additives are also needed. In contrast, physical modification methods cover a variety of different operating methods such as surface coating, plasma modification, high-energy radiation, and ultrasonic impregnation.

[0005] As a commonly used surface treatment agent, coupling agent is widely used in the interface modification between fillers and resins. It connects the matrix and reinforcement like a bridge, and significantly enhances the binding force and adhesion between the two through chemical bonding, thereby improving the mechanical properties of the material. The amount of coupling agent and the treatment time have an important influence on the mechanical and electrical properties of the composite material.

[0006] In recent years, plasma treatment has received attention in the field of physical modification. It bombards the surface of the filler with plasma. On the one hand, it improves the surface roughness and wettability and enhances the bonding with the polymer matrix; on the other hand, it stimulates active free radicals to polymerize with monomers to form more active groups. Compared with chemical etching, it reduces the loss of mechanical properties caused by surface defects, and the drying process is more environmentally friendly. However, the gas type, duration, discharge power and other conditions during plasma treatment, as well as the subsequent composite process, all play a key role in the performance of composite materials. Improper control of any link will affect the final effect.

[0007] The modification methods are mostly limited to a single coupling agent or its combination with other chemical methods, and the fillers are mostly single or combined forms of glass fiber, hollow microspheres or alumina. Therefore, in terms of insulation, lightweight and flame retardancy, epoxy resin composites still need to be further optimized. Summary of the invention

[0008] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0009] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0010] Therefore, the object of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing a lightweight insulating flame-retardant epoxy resin composite material.

[0011] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0012] The hollow glass microspheres and the hollow alumina microspheres are sequentially impregnated with acetone, washed with deionized water, and vacuum dried to obtain pretreated hollow glass microspheres and hollow alumina microspheres;

[0013] The pretreated hollow glass microspheres and hollow alumina microspheres are placed in a mixed solution of a coupling agent and anhydrous ethanol with a coupling agent concentration of 1 to 50 wt %, and stirred and immersed to obtain hollow glass microspheres and hollow alumina microspheres modified by the coupling agent. Meanwhile, montmorillonite is placed in the mixed solution of the coupling agent and anhydrous ethanol and sheared and dispersed by ball milling to obtain exfoliated montmorillonite modified by the coupling agent.

[0014] The hollow glass microspheres, hollow alumina microspheres and montmorillonite modified by the coupling agent are dried and placed in a plasma treatment chamber, and gas is introduced for plasma treatment to obtain hollow glass microspheres, hollow alumina microspheres and montmorillonite modified by plasma;

[0015] In parts by weight, 10 to 50 parts of anhydrous ethanol are added to 100 parts of epoxy resin and stirred to fully dilute the epoxy resin, and then 10 to 40 parts of a curing agent and 1 to 50 parts of plasma-modified hollow glass microspheres, 0.1 to 20 parts of alumina hollow microspheres and 0.1 to 20 parts of montmorillonite are added, the mixture is sheared and dispersed, and the obtained composite system slurry is vacuum dried, poured into a mold, and cured to finally obtain a lightweight insulating flame-retardant epoxy resin composite material.

[0016] As a preferred embodiment of the method for preparing the lightweight insulating flame-retardant epoxy resin composite material described in the present invention, the hollow glass microspheres and the hollow alumina microspheres are sequentially impregnated with acetone, washed with deionized water, and vacuum dried, wherein the acetone impregnation time is 8 to 24 hours, the vacuum drying temperature is 60 to 100° C., and the vacuum drying time is 8 to 24 hours.

[0017] As a preferred scheme of the preparation method of the lightweight insulating flame-retardant epoxy resin composite material described in the present invention, the pretreated hollow glass microspheres and alumina hollow microspheres are stirred and immersed in the mixed solution of the coupling agent and anhydrous ethanol for 2 to 12 hours, the temperature is 40 to 80°C, and the rotation speed is 100 to 500 rpm.

[0018] As a preferred embodiment of the method for preparing the lightweight insulating flame-retardant epoxy resin composite material of the present invention, the time for shear dispersion of montmorillonite in the mixed solution of the coupling agent and anhydrous ethanol by ball milling is 0.5 to 4 hours, and the rotation speed is 300 to 800 rpm.

[0019] As a preferred scheme for the preparation method of the lightweight insulating flame-retardant epoxy resin composite material described in the present invention, wherein: the coupling agent includes one or more of KH550, KH560, KH570, KH172, Z-6011, KBM-903, DL411, NDZ-201, and metal composite coupling agents.

[0020] As a preferred embodiment of the method for preparing the lightweight insulating flame-retardant epoxy resin composite material of the present invention, the drying temperature of the hollow glass microspheres, alumina hollow microspheres and montmorillonite modified by the coupling agent is 60-100°C.

[0021] As a preferred embodiment of the method for preparing the lightweight insulating flame-retardant epoxy resin composite material described in the present invention, the gas in the plasma treatment includes one or more of nitrogen, oxygen, air, hydrogen, and carbon dioxide, and the flow rate of the gas is 20 to 200 mL / min.

[0022] As a preferred solution of the method for preparing the lightweight insulating flame-retardant epoxy resin composite material described in the present invention, the power of the plasma treatment is 100-500W, the time is 600-24000s, and the vacuum degree is 500-1000Pa.

[0023] As a preferred solution of the method for preparing the lightweight insulating flame-retardant epoxy resin composite material of the present invention, the shear dispersion time of the mixture is 3 to 18 minutes, and the rotation speed is 1000 to 5000 rpm.

[0024] As a preferred embodiment of the method for preparing the lightweight insulating flame-retardant epoxy resin composite material of the present invention, the temperature for vacuum drying the composite system slurry is 30 to 60° C. and the time is 15 to 35 minutes.

[0025] As a preferred solution of the method for preparing the lightweight insulating flame-retardant epoxy resin composite material of the present invention, the curing treatment temperature is 30 to 70° C. and the curing time is 2 to 8 hours.

[0026] Another object of the present invention is to overcome the deficiencies in the prior art and provide a lightweight insulating flame-retardant epoxy resin composite material.

[0027] Beneficial effects of the present invention:

[0028] (1) The present invention uses hollow glass microspheres, hollow alumina microspheres and montmorillonite as fillers. The advantages of the two technologies of plasma treatment and coupling modification are fully integrated, and the characteristics of different fillers are combined for comprehensive modification. On the one hand, the various process parameters of plasma treatment are carefully optimized, and on the other hand, the coupling agent modification method is cleverly used to make the dispersion of the filler more uniform and the interface with the matrix more closely bonded, thereby achieving effective improvements in the lightweight, insulation and flame retardancy of epoxy resin.

[0029] (2) In addition, the present invention adopts a pre-protective measure, that is, the hollow glass microspheres are first treated with a coupling agent, and then the plasma surface treatment is performed.

[0030] (3) For multi-layer stacked montmorillonite fillers, the present invention adopts a high-efficiency stripping and surface activation modification method of stripping with a ball mill while performing surface modification with a coupling agent, which greatly increases the number of active groups on the surface and strengthens the interaction between the montmorillonite sheets and the epoxy resin.

[0031] (4) Hollow fillers make epoxy resin lighter, and alumina and coupling agent wet ball milling exfoliate dispersed montmorillonite to synergistically improve flame retardancy, achieving comprehensive optimization of lightweight, insulation, and flame retardancy. The above series of innovative measures further improve the insulation and flame retardancy of the prepared composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0033] Figure 1 This is a process flow chart of the lightweight insulating flame-retardant epoxy resin composite material prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0035] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0036] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0037] The epoxy resin used in the present invention is E44 type having at least two ethylene oxide groups in the molecule, the curing agent is an amine curing agent, the hollow glass microspheres are hollow spheres with an average particle size of 10 to 100 μm, and the average particle size of the hollow alumina microspheres is 0.5 to 1 mm.

[0038] The mold used in the present invention is a stainless steel mold, which includes an inner mold and an outer mold. Before use, the inner mold and the outer mold are cleaned, specifically wiped with alcohol to ensure that the mold surface is clean and free of impurities. After cleaning, a thermosetting epoxy resin high temperature resistant mold release agent is evenly sprayed on the surface of the inner mold and the outer mold to ensure a smooth subsequent molding process and facilitate demolding of the product.

[0039] Example 1

[0040] This embodiment provides a method for preparing a lightweight insulating flame-retardant epoxy resin composite material, specifically:

[0041] (1) First, the hollow glass microspheres and the hollow alumina microspheres were immersed in acetone for 20 h, washed with deionized water, and vacuum dried at 70 ° C for 10 h to obtain pretreated hollow glass microspheres and hollow alumina microspheres;

[0042] (2) Then, the hollow glass microspheres and hollow alumina microspheres after the above pretreatment are placed in a γ-glycidyloxypropyltrimethoxysilane (KH560) coupling agent solution and stirred and immersed at a speed of 500 rpm for 6 hours at 40°C to obtain KH560-modified hollow glass microspheres and hollow alumina microspheres, wherein the coupling agent solution consists of KH560 and anhydrous ethanol, and the concentration of KH560 compared to the coupling agent solution is 50wt%; at the same time, montmorillonite is placed in the KH560 coupling agent solution and sheared and dispersed at a ball milling speed of 800 rpm for 4 hours to obtain KH560-modified montmorillonite, wherein the coupling agent solution consists of KH560 and anhydrous ethanol, and the concentration of KH560 compared to the coupling agent solution is 50wt%, and the ball milling medium is zirconia microspheres with a diameter of 2 mm;

[0043] (3) Then, the hollow glass microspheres, alumina hollow microspheres and montmorillonite modified by KH560 were dried and placed in a plasma treatment chamber, nitrogen was introduced at a gas flow rate of 150 mL / min, the vacuum degree of the chamber was maintained at 500 Pa, and plasma treatment was performed at a power of 400 W for 24000 s to obtain plasma-modified hollow glass microspheres, alumina hollow microspheres and montmorillonite;

[0044] (4) Finally, 100 parts of epoxy resin were added to 30 parts of anhydrous ethanol by weight, and stirred at 500 rpm for 5 minutes to fully dilute the epoxy resin. Then, 30 parts of curing agent, 20 parts of hollow glass microspheres with an average particle size of 30 μm, 5 parts of hollow alumina microspheres with an average diameter of 0.7 mm, and 5 parts of montmorillonite were added. The mixture was sheared and dispersed at 2000 rpm for 8 minutes. The obtained composite system slurry was vacuum dried at 40°C for 30 minutes, poured into a mold, and cured at 70°C for 5 hours to finally obtain a hollow glass microsphere / hollow alumina microsphere / montmorillonite / epoxy resin composite material, i.e., a lightweight insulating flame-retardant epoxy resin composite material.

[0045] Example 2

[0046] This embodiment provides a method for preparing a lightweight insulating flame-retardant epoxy resin composite material, specifically:

[0047] (1) First, the hollow glass microspheres and the hollow alumina microspheres were immersed in acetone for 20 h, washed with deionized water, and vacuum dried at 70 ° C for 10 h to obtain pretreated hollow glass microspheres and hollow alumina microspheres;

[0048] (2) Then, the hollow glass microspheres and hollow alumina microspheres after the above pretreatment are placed in a γ-glycidyloxypropyltrimethoxysilane (KH560) coupling agent solution and stirred and immersed at a speed of 500 rpm for 5 hours at 40°C to obtain hollow glass microspheres and hollow alumina microspheres modified by KH560, wherein the coupling agent solution consists of KH560 and anhydrous ethanol, and the concentration of KH560 is 40wt% compared to the coupling agent solution; at the same time, montmorillonite is placed in the KH560 coupling agent solution and sheared and dispersed at a ball milling speed of 600 rpm for 3 hours to obtain montmorillonite modified by KH560, wherein the coupling agent solution consists of KH560 and anhydrous ethanol, and the concentration of KH560 is 40wt% compared to the coupling agent solution, and the ball milling medium is zirconia microspheres with a diameter of 2 mm;

[0049] (3) Then, the hollow glass microspheres, alumina hollow microspheres and montmorillonite modified by KH560 were dried and placed in a plasma treatment chamber, nitrogen was introduced at a gas flow rate of 100 mL / min, the vacuum degree of the chamber was maintained at 500 Pa, and plasma treatment was performed at a power of 400 W for 1200 s to obtain hollow glass microspheres, alumina hollow microspheres and montmorillonite modified by plasma;

[0050] (4) Finally, 100 parts of epoxy resin were added to 30 parts of anhydrous ethanol by weight, and stirred at 500 rpm for 5 minutes to fully dilute the epoxy resin. Then, 30 parts of curing agent, 20 parts of hollow glass microspheres with an average particle size of 30 μm, 5 parts of hollow alumina microspheres with an average diameter of 0.7 mm, and 5 parts of montmorillonite were added. The mixture was sheared and dispersed at 3000 rpm for 8 minutes. The obtained composite system slurry was vacuum dried at 40°C for 30 minutes, poured into a mold, and cured at 70°C for 5 hours to finally obtain a hollow glass microsphere / hollow alumina microsphere / montmorillonite / epoxy resin composite material, i.e., a lightweight insulating flame-retardant epoxy resin composite material.

[0051] Example 3

[0052] This embodiment provides a method for preparing a lightweight insulating flame-retardant epoxy resin composite material, specifically:

[0053] (1) First, the hollow glass microspheres and the hollow alumina microspheres were immersed in acetone for 10 h, washed with deionized water, and vacuum dried at 70° C. for 10 h to obtain pretreated hollow glass microspheres and hollow alumina microspheres;

[0054] (2) Then, the hollow glass microspheres and hollow alumina microspheres after the above pretreatment are placed in a γ-glycidyloxypropyltrimethoxysilane (KH560) coupling agent solution and stirred and immersed at a speed of 500 rpm for 3 hours at 40°C to obtain hollow glass microspheres and hollow alumina microspheres modified by KH560, wherein the coupling agent solution consists of KH560 and anhydrous ethanol, and the concentration of KH560 is 30wt% compared to the coupling agent solution; at the same time, montmorillonite is placed in the KH560 coupling agent solution and sheared and dispersed at a ball milling speed of 500 rpm for 2 hours to obtain montmorillonite modified by KH560, wherein the coupling agent solution consists of KH560 and anhydrous ethanol, and the concentration of KH560 is 30wt% compared to the coupling agent solution, and the ball milling medium is zirconia microspheres with a diameter of 2 mm;

[0055] (3) Then, the hollow glass microspheres, alumina hollow microspheres and montmorillonite modified by KH560 were dried and placed in a plasma treatment chamber, nitrogen was introduced at a gas flow rate of 100 mL / min, the vacuum degree of the chamber was maintained at 500 Pa, and plasma treatment was performed at a power of 500 W for 900 s to obtain hollow glass microspheres, alumina hollow microspheres and montmorillonite modified by plasma;

[0056] (4) Finally, 100 parts of epoxy resin were added to 30 parts of anhydrous ethanol by weight, and stirred at 500 rpm for 5 minutes to fully dilute the epoxy resin. Then, 30 parts of curing agent, 20 parts of hollow glass microspheres with an average particle size of 30 μm, 5 parts of hollow alumina microspheres with an average diameter of 0.7 mm, and 5 parts of montmorillonite were added. The mixture was sheared and dispersed at 3000 rpm for 8 minutes. The obtained composite system slurry was vacuum dried at 40°C for 30 minutes, poured into a mold, and cured at 70°C for 5 hours to finally obtain a hollow glass microsphere / hollow alumina microsphere / montmorillonite / epoxy resin composite material, i.e., a lightweight insulating flame-retardant epoxy resin composite material.

[0057] The tensile strength, density, limiting oxygen index and resistivity of the epoxy resin composite materials prepared in Examples 1 to 3 were tested. The results are shown in Table 1.

[0058] Table 1 Comparison of properties of epoxy resin composites prepared by different preparation methods

[0059]

[0060] It can be seen from Table 1 that the epoxy resin composite material prepared by the preparation method of the present invention is light in weight and has excellent mechanical properties, flame retardant properties and insulation properties. Among them, the tensile strength can reach up to 151.3MPa, which is about 40MPa higher than that of pure epoxy resin, the density is reduced by nearly 40%, and the resistivity can be increased by an order of magnitude.

[0061] Comparative Example 1

[0062] The difference between this comparative example and implementation 2 is that the plasma treatment time in step (3) is adjusted to 600 s.

[0063] Comparative Example 2

[0064] The difference between this comparative example and Example 3 is that the montmorillonite in step (3) is not subjected to plasma treatment.

[0065] Comparative Example 3

[0066] The difference between this comparative example and Example 2 is that the plasma treatment in step (3) is not performed.

[0067] The tensile strength, density, limiting oxygen index and resistivity of the epoxy resin composite materials prepared in Comparative Examples 1 to 3 were tested. The results are shown in Table 2.

[0068] Table 2 Effect of plasma treatment on the properties of epoxy resin composites

[0069]

[0070] It can be seen from Table 2 that shortening the plasma treatment time will lead to a decrease in the tensile strength of the epoxy resin composite material and a certain degree of decrease in the limiting oxygen index, that is, the mechanical properties and flame retardant properties of the material will deteriorate. Montmorillonite will also deteriorate in mechanical properties if it is not treated with plasma. In addition, hollow glass microspheres, hollow alumina microspheres and montmorillonite are not treated with plasma, which greatly reduces the mechanical energy of the material. This may be because the filler that is not treated with plasma has a weak interface bonding strength with the matrix, which in turn reduces the tensile strength of the material and deteriorates the mechanical properties of the material.

[0071] Comparative Example 4

[0072] The difference between this comparative example and Example 3 is that the hollow glass microspheres and hollow alumina microspheres in step (2) are not immersed in the KH560 coupling agent solution.

[0073] The epoxy resin composite material prepared in Comparative Example 4 was tested for tensile strength, density, limiting oxygen index, and resistivity. The results are shown in Table 3.

[0074] Table 3 Effect of coupling agent modification on the properties of epoxy resin composites

[0075]

[0076]

[0077] According to Table 3, it can be seen that the tensile strength of the epoxy resin composites of hollow glass microspheres and alumina hollow microspheres that have not been immersed in the KH560 coupling agent solution is also reduced. This is because the number of active groups on the surface of the filler that has not been modified by the KH560 coupling agent is small, resulting in weak interface bonding with the epoxy resin matrix.

[0078] Comparative Example 5

[0079] The difference between this comparative example and Example 3 is that hollow alumina microspheres are not added in step (4).

[0080] Comparative Example 6

[0081] The difference between this comparative example and Example 3 is that the hollow glass microspheres and hollow alumina microspheres in step (2) are not immersed in the KH560 coupling agent solution, and montmorillonite is not added in step (4).

[0082] The epoxy resin composite materials prepared in Comparative Examples 5 to 6 were tested for tensile strength, density, limiting oxygen index, and resistivity. The results are shown in Table 4.

[0083] Table 4 Performance comparison of epoxy resin composites prepared by different preparation methods

[0084]

[0085] It can be seen from Table 4 that the addition of hollow alumina microspheres increases the density of the epoxy resin composite material, while the tensile strength, limiting oxygen index and resistivity are reduced, indicating that the material becomes heavier, and the mechanical properties, flame retardant properties and insulation properties become worse. It can be seen that the addition of hollow alumina microspheres is crucial to the preparation of lightweight insulating flame retardant epoxy resin composites.

[0086] In summary, the present invention provides a lightweight insulating flame-retardant epoxy resin composite material and a preparation method thereof. First, according to different coupling agent concentrations, treatment time and treatment temperature, a specific number of active groups are formed on the surface of hollow glass microspheres, hollow alumina microspheres and montmorillonite; then, plasma surface treatment is used to introduce more active groups to the surface of hollow glass microspheres and montmorillonite, expand more sites available for binding, and further optimize their surface properties. Through this method, the interfacial bonding efficiency between the above-mentioned filler and the epoxy resin matrix is ​​greatly enhanced, so that the mechanical properties and insulation properties of the epoxy resin composite material are significantly improved, and the comprehensive properties of lightweight, insulation and flame retardancy are optimized.

[0087] On the one hand, the efficient stripping, dispersion and surface modification of montmorillonite can significantly improve the mechanical properties, insulation properties and heat resistance and high temperature performance. On the other hand, the hollow glass microspheres and alumina hollow microspheres introduced in the present invention are uniformly mixed with the matrix material to reduce the weight of the material and improve the structural stability, mechanical properties, shock absorption effect and insulation performance of the matrix material.

[0088] The method provided by the present invention is closely centered around the actual production process of hollow glass microspheres / hollow alumina microspheres / montmorillonite / epoxy resin composite materials. The focus is on optimizing the interface bonding state of the composite material, improving material properties, reducing material weight, and enhancing insulation and flame retardancy. The method is not only simple in implementation and convenient in operation, but also has strong applicability in the field of industrial production.

[0089] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a lightweight insulating flame-retardant epoxy resin composite material, characterized in that: include, The hollow glass microspheres and the hollow alumina microspheres are sequentially impregnated with acetone, washed with deionized water, and vacuum dried to obtain pretreated hollow glass microspheres and hollow alumina microspheres; The pretreated hollow glass microspheres and hollow alumina microspheres are placed in a mixed solution of a coupling agent and anhydrous ethanol with a coupling agent concentration of 1 to 50 wt %, and stirred and immersed to obtain hollow glass microspheres and hollow alumina microspheres modified by the coupling agent. Meanwhile, montmorillonite is placed in the mixed solution of the coupling agent and anhydrous ethanol and sheared and dispersed by ball milling to obtain exfoliated montmorillonite modified by the coupling agent. The hollow glass microspheres, hollow alumina microspheres and montmorillonite modified by the coupling agent are dried and placed in a plasma treatment chamber, and gas is introduced for plasma treatment to obtain hollow glass microspheres, hollow alumina microspheres and montmorillonite modified by plasma; In parts by weight, 10 to 50 parts of anhydrous ethanol are added to 100 parts of epoxy resin and stirred to fully dilute the epoxy resin, and then 10 to 40 parts of a curing agent and 1 to 50 parts of plasma-modified hollow glass microspheres, 0.1 to 20 parts of alumina hollow microspheres and 0.1 to 20 parts of montmorillonite are added, the mixture is sheared and dispersed, and the obtained composite system slurry is vacuum dried, poured into a mold, and cured to finally obtain a lightweight insulating flame-retardant epoxy resin composite material.

2. The method for preparing the lightweight insulating flame-retardant epoxy resin composite material according to claim 1, characterized in that: The hollow glass microspheres and hollow alumina microspheres are sequentially impregnated with acetone, washed with deionized water, and vacuum dried, wherein the acetone impregnation time is 8 to 24 hours, the vacuum drying temperature is 60 to 100° C., and the vacuum drying time is 8 to 24 hours.

3. The method for preparing the lightweight insulating flame-retardant epoxy resin composite material according to claim 1, characterized in that: The pretreated hollow glass microspheres and hollow alumina microspheres are stirred and immersed in the mixed solution of the coupling agent and anhydrous ethanol for 2 to 12 hours at a temperature of 40 to 80° C. and a rotation speed of 100 to 500 rpm.

4. The method for preparing the lightweight insulating flame-retardant epoxy resin composite material according to claim 1, characterized in that: The montmorillonite is sheared and dispersed in the mixed solution of the coupling agent and anhydrous ethanol by ball milling for 0.5 to 4 hours at a rotation speed of 300 to 800 rpm.

5. The method for preparing the lightweight insulating flame-retardant epoxy resin composite material according to claim 1, characterized in that: The gas used in the plasma treatment includes one or more of nitrogen, oxygen, air, hydrogen and carbon dioxide, and the flow rate of the gas is 20 to 200 mL / min.

6. The method for preparing the lightweight insulating flame-retardant epoxy resin composite material according to claim 1, characterized in that: The power of the plasma treatment is 100-500W, the time is 600-24000s, and the vacuum degree is 500-1000Pa.

7. The method for preparing the lightweight insulating flame-retardant epoxy resin composite material according to claim 1, characterized in that: The shearing and dispersing time of the mixture is 3 to 18 minutes, and the rotation speed is 1000 to 5000 rpm.

8. The method for preparing the lightweight insulating flame-retardant epoxy resin composite material according to claim 1, characterized in that: The temperature for vacuum drying the composite system slurry is 30-60° C. and the time is 15-35 minutes.

9. The method for preparing the lightweight insulating flame-retardant epoxy resin composite material according to claim 1, characterized in that: The curing treatment is performed at a temperature of 30 to 70° C. and for a time of 2 to 8 hours.

10. A lightweight insulating flame-retardant epoxy resin composite material prepared by the preparation method according to any one of claims 1 to 9.

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