A lightweight, impact-resistant, flame-retardant, and heat-insulating composite material and its preparation method.

Abstract

This invention relates to a lightweight, impact-resistant, flame-retardant, and heat-insulating composite material and its preparation method. The composite material comprises a mixture of the following components, processed at room temperature and / or high temperature to obtain the product: silicone oil, boride, silicone rubber, vulcanizate, microsphere foaming agent, and expandable graphite. The preparation method includes the following steps: a. preparing a shear-hardening adhesive using silicone oil and boride; b. mixing the product obtained in step a with silicone rubber, vulcanizate, microsphere foaming agent, and expandable graphite, and vulcanizing to obtain the composite material. The composite material integrates impact protection, heat protection, and lightweight properties, and can be widely used in human applications to protect users from various external stimuli.

Description

Technical Field

[0001] This invention belongs to the field of multifunctional protective materials, specifically relating to a lightweight, impact-resistant, flame-retardant, and heat-insulating composite material and its preparation method. Background Technology

[0002] Safety and protection have always been a hot topic in scientific research. Meanwhile, natural disasters and wars have made the design of intelligent, multifunctional protective materials of paramount importance. Introducing multifunctional fillers into single-function protective materials to impart new properties and thus cope with various external stimuli is a common method for preparing multifunctional protective materials. The development of different fillers has effectively diversified the properties of single-function protective materials.

[0003] Shear-hardening materials, as excellent protective materials with unique rate-related properties, offer a feasible strategy for impact protection. Chinese Patent CN115769920A discloses a method for preparing intelligent protective clothing with both force and heat protection functions, achieving force protection and thermal insulation through a flexible and expandable intelligent sandwich structure. Chinese Patent CN201402100 discloses a bulletproof vest made by impregnating fibers with a shear-thickening liquid, meeting the requirements for comfortable protection. Chinese Patent CN207252840U discloses a high-cushioning knee brace prepared by combining a polyurethane foam material containing shear-thickening gel with foamed silicone rubber, providing excellent protective performance for the wearer. However, single-function protective materials largely limit their application range.

[0004] On the other hand, the comfort of composite materials has always been a concern for researchers. Chinese patent CN204335927U discloses a comfortable safety helmet prepared using the protective properties of a shear-thickening fluid. However, the resulting device is bulky, and the burden it places on the wearer remains a problem to be solved. Porous structures are an effective way to reduce weight, with foam being a typical example. As a common porous lightweight material, foam is a product in high demand in today's society. However, most commercial foams are usually made of petroleum-based plastics, and due to their poor fire resistance, fire safety is a serious issue in their use. Therefore, developing lightweight protective composite materials with flame-retardant properties is of profound significance.

[0005] Current patents reveal a severe lack of research into comfortable, multifunctional protective materials capable of simultaneously protecting against external stimuli. Furthermore, the manufacturing processes for most composite materials are complex and expensive. Therefore, developing lightweight, impact-resistant, flame-retardant, and heat-insulating multifunctional composite materials is of profound significance for scientific research and daily life. Summary of the Invention

[0006] This invention addresses the shortcomings of traditional technologies by providing a lightweight, impact-resistant, flame-retardant, and heat-insulating composite material and its preparation method. The composite material possesses multifunctional protective properties, including lightweight, energy absorption, flame retardancy, and heat insulation. It exhibits excellent energy dissipation and suppression of external heat transfer, providing synergistic protection against external impacts, flame impacts, and temperature fluctuations. Notably, the raw materials required for this composite material are readily available, inexpensive, and the preparation process is simple. Therefore, this material can protect users from various external stimuli and has significant potential in the field of multifunctional lightweight protective materials.

[0007] A lightweight, impact-resistant, flame-retardant, and heat-insulating composite material, wherein the composite material is prepared by dispersing microsphere foaming agent and expandable graphite in a shear-hardening elastomer matrix.

[0008] Specifically, the present invention is achieved through the following technical solution:

[0009] A lightweight, impact-resistant, flame-retardant, and heat-insulating composite material is prepared by a mixture comprising an unvulcanized shear-hardening elastomer, a microsphere foaming agent, and expandable graphite through high-temperature, high-pressure, and high-temperature foaming treatment; wherein the unvulcanized shear-hardening elastomer is formed from a mixture comprising shear-hardening rubber, silicone rubber, and a vulcanizing agent.

[0010] Furthermore, the shear-hardening adhesive is a product obtained by polymerizing boride and silicone oil at a temperature of 150°C to 200°C. For example, the shear-hardening adhesive is a product obtained by polymerizing boride and silicone oil at temperatures of 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, or 200°C.

[0011] Further, the boride is selected from one or more of boric acid, boron oxide, borate, or boron halide; preferably, the mass ratio of the silicone oil to the boride is 5:1, 6:1, 7:1, 8:1, 10:1, 12:1, 14:1, 16:1, 18:1, 20:1, 22:1, 24:1, 26:1, 28:1, 30:1, 32:1, 34:1, 36:1, 38:1, or 40:1.

[0012] Furthermore, the microsphere foaming agent comprises thermally expandable microspheres with a core-shell structure, consisting of a shell and a core. The shell is one or more of polyacrylonitrile, polymethyl methacrylate, and polyacrylamide, and the core is a hydrocarbon.

[0013] Furthermore, the vulcanizing agent is benzoyl peroxide.

[0014] Furthermore, the high temperature and high pressure are carried out at 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C or 120°C, and at 10 MPa, 11 MPa, 13 MPa, 15 MPa, 17 MPa, 19 MPa, 20 MPa, 22 MPa, 24 MPa or 25 MPa. The high temperature foaming treatment is carried out at 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, 235°C, 240°C, 245°C or 250°C.

[0015] Furthermore, the mass ratio of shear-hardening rubber:silicone rubber:vulcanizing agent is 25–175:15–75:1–3; for example, the mass ratios of shear-hardening rubber:silicone rubber:vulcanizing agent are 25–175:15–75:1–3, 30–175:15–75:1–3, 35–175:15–75:1–3, 40–175:15–75:1–3, and 45–175:15–75:1–3. 50~175:15~75:1~3, 55~175:15~75:1~3, 60~175:15~75:1~3, 65~175:15~75:1~3, 70~175:15~75:1~3, 75~175:15~75:1~3, 80~175:15~75:1~3, 85~175:15~75:1~3, 90~175:15~7 5:1~3, 95~175:15~75:1~3, 100~175:15~75:1~3, 105~175:15~75:1~3, 110~175:15~75:1~3, 115~175:15~75:1~3, 120~175:15~75:1~3, 125~175:15~75:1~3, 130~175:15~75:1 The mass ratios are: ~3, 135~175:15~75:1~3, 140~175:15~75:1~3, 145~175:15~75:1~3, 150~175:15~75:1~3, 155~175:15~75:1~3, 160~175:15~75:1~3, 165~175:15~75:1~3, or 170~175:15~75:1~3. Preferably, the mass ratio of shear-hardening rubber: silicone rubber: vulcanizing agent is 25~175:15~75:2 or 35:15:2.

[0016] Furthermore, based on the total mass of unvulcanized shear-hardening elastomer, microsphere foaming agent, and expandable graphite, the mass fraction of the microsphere foaming agent is 5%–25% (e.g., the mass fraction of the microsphere foaming agent is 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%). The mass fraction of expandable graphite is 5% to 30% (e.g., 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%).

[0017] A method for preparing a composite material as described in any of the preceding claims, the method comprising the following steps:

[0018] a. Add the boride to the silicone oil and mix, then polymerize at 150–200°C (e.g., at 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C or 200°C).

[0019] b. Cool the reaction product obtained in step a to room temperature to obtain shear-hardening adhesive;

[0020] c. Mix the shear-hardening rubber, silicone rubber and vulcanizing agent obtained in step b to obtain an unvulcanized shear-hardening elastomer, and mix the unvulcanized shear-hardening elastomer, microsphere foaming agent and expandable graphite evenly.

[0021] d. The product obtained in step c is vulcanized under high temperature and high pressure;

[0022] e. Perform high-temperature foaming treatment on the product obtained in step d;

[0023] f. Cool the product obtained in step e to room temperature.

[0024] Furthermore, the shear-hardening elastomer is a product obtained by vulcanizing shear-hardening rubber with silicone rubber and benzoyl peroxide.

[0025] Furthermore, the shear-hardening adhesive is a product obtained by high-temperature polymerization of borate and silicone oil.

[0026] Further, the boride is one or more of boric acid, boron oxide, borate or boron halide; preferably, the mass ratio of the silicone oil to the boride is 5:1 to 40:1.

[0027] Furthermore, the vulcanization temperature of the composite material is between 50 degrees Celsius and 120 degrees Celsius, and the vulcanization pressure is between 10 MPa and 25 MPa.

[0028] The method for preparing the composite material as described above includes the following steps:

[0029] a. Add the boride to the hydroxyl silicone oil and mix;

[0030] b. Stir the mixture obtained in step a multiple times at high temperature;

[0031] c. Cool the product obtained in step b to room temperature to obtain shear-hardening adhesive;

[0032] d. Mix the shear-hardening adhesive obtained in step c with silicone rubber, benzoyl peroxide, microsphere foaming agent, and expandable graphite until homogeneous;

[0033] e. The product obtained in step d is vulcanized under high temperature and high pressure;

[0034] f. Perform high-temperature foaming treatment on the product obtained in step e;

[0035] g. Cool the product obtained in step f to room temperature.

[0036] The present invention has the following beneficial effects:

[0037] The composite material possesses multifunctional protective properties, including lightweight, energy absorption, flame retardancy, and heat insulation. It exhibits excellent energy dissipation and suppression of external heat transfer, providing synergistic protection against external impacts, flame impacts, and temperature fluctuations. The composite material can insulate against temperatures from 100°C to 54.7°C, while maintaining a temperature of -66°C at a low temperature of -103°C. It demonstrates an energy absorption capacity of up to 2.6 joules per gram per unit mass when impacted from a height of 50 cm. Furthermore, the composite material can resist flame impacts, reducing the maximum heat release rate from 390 kW / m² to 109 kW / m². Notably, the raw materials required for the composite material are readily available, inexpensive, and the manufacturing process is simple. Therefore, this material can protect users from various external stimuli and has significant potential in the field of multifunctional lightweight protective materials. Attached Figure Description

[0038] Figure 1 The rheological property curves are for the shear-hardening elastomer prepared in Example 3 and the composite materials prepared in Examples 6, 7 and 8.

[0039] Figure 2 Density diagrams of the shear-hardening elastomer prepared in Example 3 and the composite materials prepared in Examples 6, 7 and 8.

[0040] Figure 3 The thermal conductivity of the shear-hardening elastomer prepared in Example 3 and the composite materials prepared in Examples 6, 7 and 8 is given.

[0041] Figure 4 Temperature-time curves of the shear-hardening elastomer prepared in Example 3 and the composite materials prepared in Examples 6, 7 and 8 at an ambient temperature of 100 degrees Celsius.

[0042] Figure 5 Temperature-time curves of the shear-hardening elastomer prepared in Example 3 and the composite materials prepared in Examples 6 and 7 at an ambient temperature of approximately -103 degrees Celsius.

[0043] Figure 6 The energy absorbed per unit mass by the shear-hardening elastomer prepared in Example 3 and the composite materials prepared in Examples 6, 7 and 8 under different height drop hammer impacts.

[0044] Figure 7 The heat release rate curves are for the shear-hardening elastomer prepared in Example 3 and the composite materials prepared in Examples 6 and 9.

[0045] Figure 8 The image shows a vertical combustion image of the shear-hardened elastomer prepared in Example 3.

[0046] Figure 9 The image shows a vertical combustion of the composite material prepared in Example 6. Detailed Implementation

[0047] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. However, the following embodiments are only for explaining the present invention, and the scope of protection of the present invention should include all the contents of the claims. Moreover, through the description of the following embodiments, those skilled in the art can fully implement all the contents of the claims of the present invention.

[0048] The performance parameters of the samples prepared in the examples were tested according to the following test methods:

[0049] A. The specific method for testing the change of the material's storage modulus with shear frequency is as follows: Figure 1 )

[0050] The material was made into a cylinder with a diameter of 20 mm and a thickness of 1 mm, and its rheological properties were tested using a commercial rheometer (Physica MCR302, Anton Paar Co, Austria).

[0051] B. The material density is calculated as follows: Figure 2 )

[0052] ρ = m / V, where m is the mass of the composite material and V is the volume of the composite material.

[0053] C. The specific methods for testing the thermal insulation performance of materials are as follows: Figure 3 , Figure 4 , Figure 5 )

[0054] The material was fabricated into a cuboid with sides of 3 cm and a thickness of 1 cm. A high-temperature environment of 100 degrees Celsius was provided using an integrated heating machine (JF-956C, Dongguan Weiteke Automation Technology), and a low-temperature environment of approximately -103 degrees Celsius was provided using liquid nitrogen. Infrared cameras (Image IR 8300, InfraTec, Germany) were used to collect information on the material's temperature changes. The thermal conductivity of the material was determined using the transient planar heat source method (TPS2500s Hot Disk thermal constant analyzer).

[0055] D. The specific methods for measuring the protective performance of materials under drop hammer impact are as follows: Figure 6 )

[0056] The material was cut into cuboids with sides of 3 cm and a thickness of 1 cm. The testing system included a drop hammer impact tester (ZCJ1302-A, Meters Industrial), a force sensor (KD3005C, Yangzhou Kedong), a charge amplifier (YE5853, Donghua Testing), and a digital oscilloscope (Tektronix DPO 2014B). The sample was placed directly above the force sensor and connected to the digital oscilloscope via the charge amplifier. Then, a 0.55 kg drop hammer was freely released from different heights to apply impact loads. The impact force experienced by the sample was recorded in situ to characterize the sample's dissipation characteristics of impact energy.

[0057] E. The specific methods for testing the flame retardant properties of materials are as follows: Figure 7 , Figure 8 , Figure 9 )

[0058] The material was cut into cuboids with a length of 100 mm, a width of 13 mm, and a thickness of 3 mm. A vertical combustion test was conducted on the material using a CFZ-2 instrument (Jiangning Analytical Instruments Co., Ltd., China). Alternatively, a cone calorimeter with a length of 100 mm and a thickness of 3 mm was used to perform cone calorimetry tests on the material at a heat flux of 35 kW / m².

[0059] The sources of some of the raw materials used in the following embodiments of the present invention are as follows:

[0060] (1) Silicone rubber The silicone rubber mentioned above was purchased from Shenzhen Muwei Intelligent Technology Co., Ltd.

[0061] (2) The microsphere foaming agent used is 180DU45 high temperature thermal expansion microspheres provided by Wai Dian International Chemical Specialty Store. The average particle size of the microspheres is 20-50 micrometers and the reaction temperature is 120-250 degrees Celsius.

[0062] Example of a method for preparing unvulcanized shear-hardening elastomers:

[0063] Example 1:

[0064] Take the following raw materials in the following mass ratio:

[0065] Silicone oil: boric acid = 5:1

[0066] Shear hardening rubber: silicone rubber = 7:3

[0067] Shear-hardening adhesive: Benzoyl peroxide = 35:2.

[0068] Silicone oil and boric acid were mixed evenly and heated in an oven at 180 degrees Celsius, stirring every 15 minutes. When no liquid silicone oil remained, a small amount of octanoic acid (250 μL / 100g silicone oil) was added and stirred evenly. The mixture was then heated in the oven at 180 degrees Celsius for another 30 minutes. After heating, it was removed and cooled to room temperature to obtain shear-hardening rubber. The shear-hardening rubber was then mixed evenly with silicone rubber and benzoyl peroxide to obtain an uncured shear-hardening elastomer.

[0069] Among them, the product obtained by vulcanizing unvulcanized shear-hardening elastomer at 100 degrees Celsius and 20 MPa for 15 minutes using a flat vulcanizing machine is called shear-hardening elastomer.

[0070] Example 2:

[0071] Take the following raw materials in the following mass ratio:

[0072] Silicone oil: boric acid = 15:1, other parameters are the same as in Example 1.

[0073] Example 3:

[0074] Take the following raw materials in the following mass ratio:

[0075] Silicone oil: boric acid = 30:1

[0076] The rest is the same as in Example 1.

[0077] Example 4:

[0078] Take the following raw materials in the following mass ratio:

[0079] Silicone oil: boric acid = 40:1

[0080] The rest is the same as in Example 1.

[0081] Example 5:

[0082] Take the following raw materials in the following mass ratio:

[0083] Shear-hardening rubber: Silicone rubber = 6:5

[0084] The rest is the same as in Example 1.

[0085] Examples of preparation methods for lightweight, impact-resistant, flame-retardant, and heat-insulating composite materials:

[0086] Example 6:

[0087] Take the following raw materials in the following mass ratio:

[0088] Unvulcanized shear-hardened elastomer: microsphere foaming agent = 9:1

[0089] Expandable graphite with a total mixture mass fraction of 10%

[0090] The obtained sample is denoted as composite material -10% -10%.

[0091] The unvulcanized shear-hardening elastomer was prepared in Example 3.

[0092] The microsphere foaming agent used was 180DU45 high-temperature thermally expandable microspheres supplied by Wai Dian International Chemical Specialty Store. These expandable microspheres consist of a polyacrylonitrile outer shell and a hydrocarbon core. Similarly, microsphere foaming agents with outer shells composed of polymethyl methacrylate and polyacrylamide can also be used in uncured shear-hardening elastomers to improve mechanical and thermal properties and meet lightweight requirements. Therefore, further examples are not provided.

[0093] First, the uncured shear-hardened elastomer, microsphere foaming agent, and 10% (by mass) expandable graphite were mixed evenly. The resulting mixture was then pressed into a mold and vulcanized at 100°C and 20 MPa for 15 minutes using a flat vulcanizing machine. The vulcanized sample was then placed in a 180°C oven for 10 minutes for high-temperature foaming treatment. After cooling to room temperature, the sample was collected.

[0094] Example 7:

[0095] Take the following raw materials in the following mass ratio:

[0096] Unvulcanized shear-hardened elastomer: microsphere foaming agent = 19:1

[0097] Expandable graphite with a total mixture mass fraction of 10%

[0098] Other procedures are the same as in Example 6. The obtained sample is denoted as composite material - 5% - 10%.

[0099] Example 8:

[0100] Take the following raw materials in the following mass ratio:

[0101] Unvulcanized shear-hardened elastomer: microsphere foaming agent = 4:1

[0102] Expandable graphite with a total mixture mass fraction of 10%

[0103] Other procedures are the same as in Example 6. The obtained sample is denoted as Composite Material - 20% - 10%.

[0104] Example 9:

[0105] 5% expandable graphite in total mixture

[0106] Other procedures are the same as in Example 6. The obtained sample is denoted as Composite Material - 10% - 5%.

[0107] The lightweight, impact-resistant, flame-retardant, and heat-insulating composite material obtained in this invention exhibits typical shear hardening properties at different shear frequencies. With increasing shear frequency, the storage modulus of the multifunctional composite material significantly increases. Figure 1 It can be seen that the storage modulus values ​​are as follows: shear-hardened elastomer < composite material -5% -10% < composite material -10% -10% < composite material -20% -10%. At a shear frequency of 0.1 Hz, the storage modulus of the shear-hardened elastomer is 3979.3 Pa, the storage modulus of the composite material -5% -10% is 47621 Pa, the storage modulus of the composite material -10% -10% is 106330 Pa, and the storage modulus of the composite material -20% -10% is 192950 Pa. At a shear frequency of 100 Hz, the storage modulus of the shear-hardened elastomer is 143370 Pa, the storage modulus of the composite material -5% -10% is 195010 Pa, the storage modulus of the composite material -10% -10% is 346210 Pa, and the storage modulus of the composite material -20% -10% is 607770 Pa.

[0108] This composite material has a low density, see Figure 2 The density of shear-hardening elastomer is 0.97615 g / cm³, the density of composite material -5%-10% is 0.29411 g / cm³, the density of composite material -10%-10% is 0.11603 g / cm³, and the density of composite material -20%-10% is 0.05876 g / cm³.

[0109] The thermal conductivity of the shear-hardened elastomer and the composite material was tested at different temperatures. The composite material exhibits low thermal conductivity, demonstrating its good thermal insulation performance. (See attached image) Figure 3The thermal conductivity of the shear-hardening elastomer at temperatures of 5, 24, 40, 60, 80, and 100 °C is 0.172, 0.172, 0.173, 0.169, and 0.16 W / (m·Kelvin), respectively; the thermal conductivity of the composite material (-5%-10%) at temperatures of 5, 24, 40, 60, 80, and 100 °C is 0.091, 0.092, 0.095, 0.095, and 0.09, respectively. 5; The thermal conductivity of composite material -10%-10% at temperatures of 5, 24, 40, 60, 80 and 100℃ is 0.049, 0.052, 0.053, 0.057 and 0.059, respectively; The thermal conductivity of composite material -20%-10% at temperatures of 5, 24, 40, 60, 80 and 100℃ is 0.039, 0.041, 0.044, 0.047 and 0.048, respectively.

[0110] At an ambient temperature of 100 degrees Celsius, the steady-state temperature of this composite material is significantly lower than that of shear-hardened elastomers, revealing its superiority for thermal shock protection. (See...) Figure 4 The steady-state temperature of the shear-hardened elastomer is approximately 73.5 degrees Celsius, and the steady-state time is approximately 330 seconds; the steady-state temperature of the composite material with a -5% to -10% content is approximately 57.4 degrees Celsius, and the steady-state time is approximately 630 seconds; the steady-state temperature of the composite material with a -10% to -10% content is approximately 54.7 degrees Celsius, and the steady-state time is approximately 770 seconds; the steady-state temperature of the composite material with a -20% to -10% content is approximately 47.4 degrees Celsius, and the steady-state time is approximately 950 seconds.

[0111] As the temperature decreased from ambient temperature to approximately -103 degrees Celsius, the steady-state temperature difference of the composite material remained at a high level. At 835 seconds, the temperature of the shear-stiffened elastomer decreased to -81 degrees Celsius, the temperature of the composite material (-5%-10%) decreased to -71 degrees Celsius, and the temperature of the composite material (-10%-10%) decreased to -66 degrees Celsius, which is superior to that of the shear-stiffened elastomer. This indicates that the composite material possesses good thermal insulation performance. Figure 5 ;

[0112] Under drop hammer impact tests at different heights, the composite material exhibits a high energy absorption per unit mass, indicating that the impact kinetic energy is effectively dissipated. Figure 6 For example, when the drop height is 30 cm, the energy absorbed per unit mass is as follows: 0.2 joules / gram for shear-hardened elastomer, 0.66 joules / gram for composite material -5%-10%, 0.9 joules / gram for composite material -10%-10%, and 2.37 joules / gram for composite material -20%-10%.

[0113] Conical calorimetry tests were conducted at a heat flux of 35 kW / m². The heat release rates of the composite material (-10%-5%) and the composite material (-10%-10%) were significantly lower than those of the shear-hardened elastomer, indicating better fire protection performance. (See...) Figure 7 The maximum heat release rate of composite materials (-10% - 5%) is 152 kW / m². The maximum heat release rate of composite materials (-10% - 10%) is 109 kW / m². The maximum heat release rate of shear-hardening elastomers is 390 kW / m².

[0114] Vertical burning tests were conducted on the shear-hardening elastomer and the composite material. Under the same ignition time, the shear-hardening elastomer burned violently, while the composite material did not produce an open flame, demonstrating the excellent flame-retardant properties of the composite material. (See...) Figure 8 , Figure 9 . Figure 9 The image represents the vertical burning of the composite material at -10% -10%. The two 10-second intervals in the image above represent the 10th second of ignition. The second 10-second interval indicates that the material did not burn at the moment the flame was removed, so it is still the 10th second.

[0115] The parts of this invention not described in detail are well-known to those skilled in the art. The embodiments described above are merely preferred embodiments of the invention, and do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Various modifications and improvements to the technical solutions of this invention made by those skilled in the art without departing from the spirit of the invention should fall within the protection scope defined by the claims of this invention.

Claims

1. A lightweight, impact-resistant, flame-retardant, and heat-insulating composite material, characterized in that, The composite material is prepared by high-temperature, high-pressure and high-temperature foaming treatment of a mixture comprising an unvulcanized shear-hardening elastomer, a microsphere foaming agent and expandable graphite; the unvulcanized shear-hardening elastomer is formed by a mixture comprising shear-hardening rubber, silicone rubber and a vulcanizing agent; the shear-hardening rubber is obtained by polymerization of borate and silicone oil, wherein the mass ratio of silicone oil to borate is 5:1 to 40:1; the mass ratio of shear-hardening rubber:silicone rubber:vulcanizing agent is 25~175:15~75:1~3; based on the total mass of the unvulcanized shear-hardening elastomer, microsphere foaming agent and expandable graphite, the mass fraction of microsphere foaming agent is 5%~25% and the mass fraction of expandable graphite is 5%~30%.

2. The composite material according to claim 1, characterized in that, The shear-hardening adhesive is a product obtained by polymerizing borate and silicone oil at a temperature of 150°C to 200°C.

3. The composite material according to claim 2, characterized in that, The boride is selected from one or more of boric acid, boron oxide, borate or boron halide.

4. The composite material according to claim 1, characterized in that, The microsphere foaming agent consists of thermally expandable microspheres with a core-shell structure, composed of a thermoplastic polyacrylate polymer outer shell and a hydrocarbon core.

5. The composite material according to claim 1, characterized in that, The microsphere foaming agent consists of thermally expandable microspheres with a core-shell structure, comprising a shell and a core. The shell is one or more of polyacrylonitrile, polymethyl methacrylate, and polyacrylamide, and the core is a hydrocarbon.

6. The composite material according to claim 1, characterized in that, The vulcanizing agent is benzoyl peroxide.

7. The composite material according to claim 1, characterized in that, The high temperature and high pressure are carried out at 50°C to 120°C and 10 MPa to 25 MPa, and the high temperature foaming treatment is carried out at 150°C to 250°C.

8. The composite material according to claim 1, characterized in that, The mass ratio of shear hardening elastomer to silicone rubber to vulcanizing agent is 30~175:15~75:1~3; based on the total mass of unvulcanized shear hardening elastomer, microsphere foaming agent and expandable graphite, the mass fraction of microsphere foaming agent is 6%~24% and the mass fraction of expandable graphite is 6%~29%.

9. A method for preparing a composite material as described in any one of claims 1-8, characterized in that, The method includes the following steps: a. Add the boride to the silicone oil, mix, and polymerize at 150~200℃; b. Cool the reaction product obtained in step a to room temperature to obtain shear-hardening adhesive; c. Mix the shear-hardening rubber, silicone rubber and vulcanizing agent obtained in step b to obtain an unvulcanized shear-hardening elastomer, and mix the unvulcanized shear-hardening elastomer, microsphere foaming agent and expandable graphite evenly. d. The product obtained in step c is vulcanized under high temperature and high pressure; e. Perform high-temperature foaming treatment on the product obtained in step d; f. Cool the product obtained in step e to room temperature.

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