Flexible damping noise reduction composite material and application thereof

Abstract

The invention discloses a flexible damping noise reduction composite material and application thereof, and relates to the field of damping materials. Efficient absorption of broadband noise is achieved through the design of a double-layer gradient structure of the flexible damping noise reduction composite material. According to the outer layer, carbon fibers and polyester fibers are woven in a three-dimensional mode to form a compact network, and micron-sized modified paraffin phase change microcapsules are embedded into the compact network; in the inner layer, a loose framework is constructed by basalt fibers and polyester fibers, coarse supporting fibers are combined with flexible fibers, and nano silicon dioxide aerogel is loaded. Due to the double-layer synergistic effect, the sound absorption coefficient of the composite material in the full frequency band is improved, the tensile strength is improved, and the composite material has the characteristics of high strength, broadband noise reduction and temperature self-adaption. According to the invention, the noise of the emergency diesel generator or the electric emergency generator car can be reduced to the maximum in all directions, and the emergency diesel generator or the electric emergency generator car can be protected in severe environments such as wind, rain, snow and the like. The damping material prepared by the invention has the effects of high strength and noise reduction.

Description

Technical Field

[0001] The present invention relates to the technical field of damping materials, and specifically to a flexible damping and noise-reducing composite material and its application. Background Art

[0002] Waterborne damping coatings generally consist of polymer emulsions, additives, fillers, etc. The polymer emulsion is the basis of the waterborne damping coating and also the main provider of damping performance. Different additives and fillers have different effects on various properties of the coating.

[0003] The polymer matrix of the damping coating is a viscoelastic material. Under the action of alternating stress, a phenomenon of deformation lagging behind the stress change will occur, and energy will be lost in each stress cycle. When noise or vibration is transmitted to the polymer material, mechanical vibration will be converted into the movement of chain segments or macromolecular chains, and then through the internal friction between molecules, mechanical energy will be converted into heat energy, thereby achieving the damping effect. Usually, the size of the loss factor tanσ (the tangent value of the phase cut angle where the deformation lags behind the stress) is used to measure the damping performance.

[0004] Generally, when the polymer matrix material of the damping coating is near the glass transition temperature, due to a significant decrease in its modulus, it has a high loss factor and can absorb a large amount of vibration energy, thus showing relatively significant mechanical damping characteristics. Engineering practice shows that a good damping material should exhibit a high loss factor (tanσ > 0.3) in a temperature range of at least 60 - 80°C. Therefore, the temperature range corresponding to tanσ > 0.3 is usually also called the effective damping temperature range. Summary of the Invention

[0005] The purpose of the present invention is to provide a flexible damping and noise-reducing composite material and its application to solve the problems existing in the prior art.

[0006] To solve the above technical problems, the present invention provides the following technical solution: A flexible damping and noise-reducing composite material, which is prepared by three-dimensional weaving to form a composite inner and outer layer gradient structure and is prepared by combining a waterproof layer and a coating, and includes the following preparation steps:

[0007] (1) Place the carbon fiber in a plasma reaction chamber and perform surface etching treatment for 20 min with a mixed gas of Ar / O2 at a power of 100 - 300 W, where the volume ratio of Ar to O2 is 4:1; degrease the polyester fiber with N,N-dimethylformamide solvent, ultrasonically vibrate it in a constant temperature bath at 60 °C for 30 min, with a solid-liquid ratio of 1:15 and an ultrasonic power of 40 kHz; after three-dimensional weaving, immerse the prefabricated fabric in an epoxy dispersion containing 1 - 5 wt% modified paraffin phase change microcapsules, and perform treatment at 40 - 60 °C for 30 - 60 min with the assistance of 40 kHz ultrasonic waves to complete the microcapsule embedding, thus obtaining the outer layer material;

[0008] (2) After etching basalt fiber with 1 - 5% nitric acid solution at 50 °C for 1 h, mix it with polyester fiber treated by an opener according to a mass ratio of 3:7. The opener has a tooth pitch of 0.5 mm and a rotational speed of 1000 - 2000 rpm to obtain the fiber matrix; place the fiber matrix in a vacuum impregnation tank and compound it with the aerogel precursor for 1 - 2 h, with a vacuum degree of -0.095 MPa. Subsequently, perform gradient curing in a programmable temperature oven: increase the temperature from 80 °C to 120 °C at a rate of 2 °C / min and hold for 1 - 2 h, then increase the temperature to 160 °C and cure for 2 - 3 h to obtain the inner layer material;

[0009] (3) Compound the inner layer material and the outer layer material;

[0010] (4) Select a cylindrical roller made of 200 mm wool or chemical fiber, immerse the roller 10 mm deep in the coating, with a uniform pulling speed of 0.2 m / s, roll the roller at a speed of 0.8 m / min in the same direction to coat the water-based damping coating on the composite material; dry the coated flexible damping composite material at 60 °C for 10 min to finally form the film damping and noise reduction composite material.

[0011] 2. According to the preparation method of a flexible damping and noise reduction composite material described in claim 1, the preparation method of the modified paraffin phase change microcapsules in step (1) is as follows: graft stearic acid to the paraffin molecular chain at 120 - 130 °C for 2 h by the melt blending method, and the mass ratio of stearic acid to paraffin is 10:1 - 2; subsequently, encapsulate it by the interfacial polymerization method, use toluene - 2,4 - diisocyanate as the oil phase monomer and ethylenediamine as the water phase monomer, react in a system with an oil-water volume ratio of 1:3 for 4 h to form microcapsules, and then perform 50 - 100 cycles of Al2O3 coating by an atomic layer deposition device at a substrate temperature of 120 °C.

[0012] Furthermore, the mass ratio of stearic acid to paraffin is 10:1 - 2.

[0013] Further, the three-dimensional braiding in step (1) is as follows: The pretreated fibers are three-dimensionally braided on a rapier loom with a warp density of 28 pre-treated carbon fibers per cm and a weft density of 24 pre-treated polyester fibers per cm.

[0014] Further, the preparation method of the aerogel precursor in step (2) is: Tetraethoxysilane, ethanol, and deionized water are mixed in a volume ratio of 1:4:4, and the pH is adjusted to 3 with hydrochloric acid and then hydrolyzed and polycondensed for 24 h to obtain the aerogel precursor.

[0015] Further, the composite preparation method in step (3) is: After activating the inner and outer layer interfaces with He atmosphere plasma at a power of 500 W for 3 - 5 min, an epoxy-polyurethane blend adhesive with a solid content of 45% is coated, and laminated at 0.5 MPa pressure and 180 °C for 15 - 30 min by a hot press, and finally post-cured at 80 °C for 8 h to obtain a 1 mm thick composite material.

[0016] Further, the mass ratio of epoxy resin E44 to polyurethane prepolymer is 3:1.

[0017] Further, the preparation method of the waterborne damping coating in step (4) is: 5 parts of mica powder and 3 parts of silica white are treated with KH-550 silane coupling agent at 0.02 times the total mass of the fillers, ultrasonically dispersed at 60 °C and 40 kHz for 1 h and then added to the blend emulsion, and then 5% of triethylene glycol dimethacrylate, 4% of waterborne flame retardant FR713, and 0.8% of methylphenyl polyether silicone are added in sequence, and stirred at 240 rpm for 30 min to obtain the waterborne damping coating.

[0018] Further, the preparation method of the blend emulsion is: 3 parts of styrene-acrylic emulsion and 2 parts of acrylate emulsion are blended and stirred at 500 rpm for 30 min at 25 °C to form a uniform blend emulsion.

[0019] Further, the mass ratio of the fillers to the blend emulsion is 1:1.3 - 1.7.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0021] The present invention prepares a composite inner and outer layer gradient structure by three-dimensional braiding, combines a waterproof layer and a coating to prepare a flexible damping and noise reduction composite material, so as to achieve the effects of high strength and noise reduction.

[0022] The present invention realizes the efficient absorption of broadband noise through the design of a double-layer gradient structure of a flexible damping and noise-reducing composite material: the outer layer is formed by three-dimensionally weaving carbon fiber and polyester fiber into a dense network, combining high-density support fibers and flexible fibers, and embedding micron-scale modified paraffin phase change microcapsules. The metal oxide coating on its surface can reflect high-frequency sound waves, while the small-aperture pores absorb medium-frequency noise through the viscous effect. The paraffin phase change characteristics further broaden the temperature range adaptability; the inner layer constructs a loose framework with basalt fiber and polyester fiber, combines thick support fibers and flexible fibers, and loads nano-silica aerogel. Its nano-scale porous network efficiently converts the low-frequency noise energy into heat by prolonging the sound wave propagation path and frictional interaction with air molecules. Combining the ultra-low density and extremely low thermal conductivity of the aerogel, while achieving lightweight, it suppresses thermal feedback and ensures that the material maintains stable damping performance in a low-temperature environment. The synergistic effect of the double layer improves the sound absorption coefficient of the composite material in the full frequency band and enhances the tensile strength, combining high strength, broadband noise reduction, and temperature adaptability.

[0023] The present invention can maximize the reduction of the noise of emergency diesel generators or power emergency vehicles in all directions, enabling power repair work not to affect the rest, work, and life of nearby residents, and playing a protective role for emergency diesel generators or power emergency vehicles in harsh environments such as wind, rain, and snow. A flexible damping and noise-reducing composite material of the present invention is integrated, lightweight, flexible, easy to store, has high tensile strength, has a good damping and noise-reducing effect, reaches V0 level in flame retardancy, is weather-resistant, waterproof, green, and environmentally friendly. Specific embodiments

[0024] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0025] In order to more clearly illustrate the method provided by the present invention, the following embodiments are used for detailed description. The test methods for various indicators of a flexible damping and noise-reducing composite material prepared in the following embodiments are as follows:

[0026] Damping loss factor: The damping materials prepared in the examples and comparative examples are tested in accordance with GB / T 18258-2000, with a frequency range of 50 - 5000 Hz, and the average data at -20°C to 50°C is calculated.

[0027] Flame retardancy: The damping materials prepared in the examples and comparative examples are tested in accordance with UL94.

[0028] Tensile strength: The damping materials prepared in the examples and comparative examples are tested for tensile strength.

[0029] Example 1

[0030] (1) Place the carbon fiber in a plasma reaction chamber, and perform surface etching treatment for 20 min at a power of 100 W using an Ar / O2 mixed gas with a volume ratio of Ar to O2 of 4:1; perform N,N-dimethylformamide solvent degreasing treatment on the polyester fiber, ultrasonically vibrate in a constant temperature bath at 60 °C for 30 min, with a solid-liquid ratio of 1:15 and an ultrasonic power of 40 kHz; graft stearic acid onto the paraffin molecular chain at 120 °C for 2 h by melt blending method for the modified paraffin phase change microcapsules, with a mass ratio of stearic acid to paraffin of 10:1; then encapsulate by interfacial polymerization method, using toluene-2,4-diisocyanate as the oil-phase monomer and ethylenediamine as the water-phase monomer, react for 4 h in a system with an oil-water volume ratio of 1:3 to form microcapsules, and then perform 50 cycles of Al2O3 coating at a substrate temperature of 120 °C through an atomic layer deposition device; weave the treated fiber three-dimensionally on a rapier loom with a warp density of 28 threads / cm and a weft density of 24 threads / cm, and then immerse the prefabricated fabric in an epoxy dispersion containing 1 wt% microcapsules, and complete the microcapsule embedding at 40 °C for 30 min under 40 kHz ultrasonic assistance to obtain the outer layer material;

[0031] (2) After etching the basalt fiber with 1% nitric acid solution at 50 °C for 1 h, mix it with the polyester fiber treated by an opener according to a mass ratio of 3:7, with an opener tooth pitch of 0.5 mm and a rotation speed of 1000 rpm; prepare SiO2 aerogel by sol-gel method: mix tetraethoxysilane, ethanol, and deionized water according to a volume ratio of 1:4:4, adjust the pH to 3 with hydrochloric acid and then hydrolyze and polycondense for 24 h to obtain the aerogel precursor; place the fiber matrix in a vacuum impregnation tank and composite it with the aerogel precursor for 1 h, with a vacuum degree of -0.095 MPa, and then perform gradient curing in a programmable temperature oven: raise the temperature from 80 °C to 120 °C at a rate of 2 °C / min and hold for 1 h, and then raise the temperature to 160 °C and cure for 2 h to obtain the inner layer material;

[0032] (3) After activating the interface between the inner and outer layers with He atmosphere plasma at a power of 500 W for 3 min, coat an epoxy-polyurethane blend adhesive, where the mass ratio of epoxy resin E44 to polyurethane prepolymer is 3:1 and the solid content is 45%, laminate at 0.5 MPa pressure and 180 °C for 15 min through a hot press, and finally post-cure at 80 °C for 8 h to obtain a 1 mm thick composite material;

[0033] (4) Blend 3 parts of styrene-acrylic emulsion and 2 parts of acrylate emulsion, and stir at 500 rpm for 30 min at 25 °C to form a uniformly mixed emulsion; the damping filler is 5 parts of mica powder and 3 parts of silica white, which are treated with KH-550 silane coupling agent at 0.02 times the total mass of the filler, ultrasonically dispersed at 40 kHz for 1 h at 60 °C and then added to the blended emulsion. The mass ratio of the filler to the blended emulsion is 1:1.3. Then, add triethylene glycol dimethacrylate at 5% of the total mass of the emulsion, 4% waterborne flame retardant FR713, and 0.8% methylphenyl polyether silicone in sequence, and stir at 240 rpm for 30 min to obtain the waterborne damping coating; select a cylindrical roller made of 200 mm wool or chemical fiber, immerse the roller 10 mm deep into the coating, and the uniform pulling speed is 0.2 m / s. Roll the roller in the same direction at a speed of 0.8 m / min to coat the waterborne damping coating onto the composite material; the coated flexible damping composite material is dried at 60 °C for 10 min to finally form a film damping and noise reduction composite material.

[0034] Example 2

[0035] (1) Place the carbon fiber in a plasma reaction chamber, and perform surface etching treatment for 20 min at a power of 200 W using an Ar / O2 mixed gas with a volume ratio of Ar to O2 of 4:1; perform N,N-dimethylformamide solvent degreasing treatment on the polyester fiber, ultrasonically vibrate in a constant temperature bath at 60 °C for 30 min, the solid-liquid ratio is 1:15, and the ultrasonic power is 40 kHz; the modified paraffin phase change microcapsules graft stearic acid onto the paraffin molecular chain at 125 °C for 2 h by melt blending method, and the mass ratio of stearic acid to paraffin is 10:1.5; then use interfacial polymerization method for encapsulation, use toluene-2,4-diisocyanate as the oil-phase monomer and ethylenediamine as the water-phase monomer, and react in a system with an oil-water volume ratio of 1:3 for 4 h to form microcapsules, and then perform 75 cycles of Al2O3 coating at a substrate temperature of 120 °C through an atomic layer deposition device; the treated fibers are three-dimensionally woven on a rapier loom with a warp density of 28 threads / cm and a weft density of 24 threads / cm, and then immerse the prefabricated fabric in an epoxy dispersion containing 3 wt% microcapsules, and treat at 50 °C for 45 min under 40 kHz ultrasonic assistance to complete the embedding of the microcapsules to obtain the outer layer material;

[0036] (2) After the basalt fibers are etched with 3% nitric acid solution at 50 °C for 1 h, they are mixed with polyester fibers treated by an opener at a mass ratio of 3:7. The opener has a tooth pitch of 0.5 mm and a rotational speed of 1500 rpm. The SiO2 aerogel is prepared by the sol-gel method: tetraethoxysilane, ethanol, and deionized water are mixed at a volume ratio of 1:4:4, and the pH is adjusted to 3 with hydrochloric acid, followed by hydrolysis and polycondensation for 24 h to obtain the aerogel precursor. The fiber matrix is placed in a vacuum impregnation tank and compounded with the aerogel precursor for 1.5 h under a vacuum of -0.095 MPa. Subsequently, gradient curing is carried out in a programmable temperature oven: it is heated from 80 °C to 120 °C at a rate of 2 °C / min and held for 1.5 h, and then heated to 160 °C for curing for 2.5 h to obtain the inner layer material;

[0037] (3) After the interface between the inner and outer layers is activated by He atmosphere plasma with a power of 500 W for 4 min, an epoxy-polyurethane blend adhesive is coated, where the mass ratio of epoxy resin E44 to polyurethane prepolymer is 3:1 and the solid content is 45%. It is laminated at 0.5 MPa pressure and 180 °C for 22.5 min by a hot press, and finally post-cured at 80 °C for 8 h to obtain a composite material with a thickness of 1 mm;

[0038] (4) 3 parts of styrene-acrylic emulsion and 2 parts of acrylate emulsion are blended and stirred at 500 rpm for 30 min at 25 °C to form a uniform mixed emulsion. The damping filler is 5 parts of mica powder and 3 parts of white carbon black, which are treated with KH-550 silane coupling agent at 0.02 times the total mass of the filler, ultrasonic dispersed at 60 °C and 40 kHz for 1 h, and then added to the blended emulsion. The mass ratio of the filler to the blended emulsion is 1:1.5. Then, 5% of triethylene glycol dimethacrylate, 4% of waterborne flame retardant FR713, and 0.8% of methylphenyl polyether silicone are added in sequence, and stirred at 240 rpm for 30 min to obtain the waterborne damping coating. A cylindrical roller made of 200 mm wool or chemical fiber is selected, the roller is immersed in the coating to a depth of 10 mm, the uniform lifting speed is 0.2 m / s, and the roller is rolled in the same direction at a speed of 0.8 m / min to coat the waterborne damping coating on the composite material. The coated flexible damping composite material is dried at 60 °C for 10 min, and finally a film damping and noise reduction composite material is formed.

[0039] Example 3

[0040] (1) Place the carbon fiber in a plasma reaction chamber and perform surface etching treatment for 20 min at a power of 300 W using a mixed gas of Ar / O2 with a volume ratio of Ar to O2 of 4:1; degrease the polyester fiber with N,N-dimethylformamide solvent, ultrasonically vibrate it in a constant temperature bath at 60 °C for 30 min, with a solid-liquid ratio of 1:15 and an ultrasonic power of 40 kHz; graft stearic acid onto the paraffin molecular chain at 130 °C for 2 h by melt blending method to prepare modified paraffin phase change microcapsules, with a mass ratio of stearic acid to paraffin of 10:2; then encapsulate by interfacial polymerization method, using toluene-2,4-diisocyanate as the oil-phase monomer and ethylenediamine as the water-phase monomer, react for 4 h in a system with an oil-water volume ratio of 1:3 to form microcapsules, and then perform 100 cycles of Al2O3 coating at a substrate temperature of 120 °C by atomic layer deposition equipment; weave the treated fiber on a rapier loom with a warp density of 28 threads / cm and a weft density of 24 threads / cm in three dimensions, and then immerse the prefabricated fabric in an epoxy dispersion containing 5 wt% microcapsules, and treat it at 60 °C for 60 min with ultrasonic assistance at 40 kHz to complete the embedding of microcapsules, thus obtaining the outer layer material;

[0041] (2) After etching the basalt fiber with 5% nitric acid solution at 50 °C for 1 h, mix it with the polyester fiber treated by an opener in a mass ratio of 3:7, with the opener tooth pitch of 0.5 mm and a rotational speed of 2000 rpm; prepare SiO2 aerogel by sol-gel method: mix tetraethoxysilane, ethanol, and deionized water in a volume ratio of 1:4:4, adjust the pH to 3 with hydrochloric acid and then hydrolyze and polycondense for 24 h to obtain the aerogel precursor; place the fiber matrix in a vacuum impregnation tank and composite it with the aerogel precursor for 2 h, with a vacuum degree of -0.095 MPa, and then perform gradient curing in a programmable temperature oven: heat from 80 °C to 120 °C at a rate of 2 °C / min and hold for 2 h, then rise to 160 °C and cure for 3 h to obtain the inner layer material;

[0042] (3) After activating the interface between the inner and outer layers with He atmosphere plasma at a power of 500 W for 5 min, coat an epoxy-polyurethane blend adhesive, where the mass ratio of epoxy resin E44 to polyurethane prepolymer is 3:1 and the solid content is 45%, laminate it at a pressure of 0.5 MPa and a temperature of 180 °C for 30 min by a hot press, and finally post-cure at 80 °C for 8 h to obtain a composite material with a thickness of 1 mm;

[0043] (4) Blend 3 parts of styrene-acrylic emulsion and 2 parts of acrylate emulsion, and stir at 500 rpm for 30 min at 25 °C to form a uniformly mixed emulsion; the damping filler is 5 parts of mica powder and 3 parts of silica white, which are treated with KH-550 silane coupling agent at 0.02 times the total mass of the filler, ultrasonically dispersed at 40 kHz for 1 h at 60 °C, and then added to the blended emulsion. The mass ratio of the filler to the blended emulsion is 1:1.7. Then, add 5% of triethylene glycol dimethacrylate, 4% of waterborne flame retardant FR713, and 0.8% of methylphenyl polyether silicone to the total mass of the emulsion in sequence, and stir at 240 rpm for 30 min to obtain the waterborne damping coating; select a cylindrical roller made of 200 mm wool or chemical fiber, immerse the roller 10 mm deep into the coating, with a uniform lifting speed of 0.2 m / s, roll the roller in the same direction at a speed of 0.8 m / min, and apply the waterborne damping coating to the composite material; dry the coated flexible damping composite material at 60 °C for 10 min to finally form a film damping noise reduction composite material.

[0044] Comparative Example 1

[0045] The difference between Comparative Example 1 and Example 2 is that steps (2) and (3) are not included. Modify step (4) as follows: Blend 3 parts of styrene-acrylic emulsion and 2 parts of acrylate emulsion, and stir at 500 rpm for 30 min at 25 °C to form a uniformly mixed emulsion; the damping filler is 5 parts of mica powder and 3 parts of silica white, which are treated with KH-550 silane coupling agent at 0.02 times the total mass of the filler, ultrasonically dispersed at 40 kHz for 1 h at 60 °C, and then added to the blended emulsion. The mass ratio of the filler to the blended emulsion is 1:1.5. Then, add 5% of triethylene glycol dimethacrylate, 4% of waterborne flame retardant FR713, and 0.8% of methylphenyl polyether silicone to the total mass of the emulsion in sequence, and stir at 240 rpm for 30 min to obtain the waterborne damping coating; select a cylindrical roller made of 200 mm wool or chemical fiber, immerse the roller 10 mm deep into the coating, with a uniform lifting speed of 0.2 m / s, roll the roller in the same direction at a speed of 0.8 m / min, and apply the waterborne damping coating to the outer material; dry the coated flexible damping composite material at 60 °C for 10 min to finally form a film damping noise reduction composite material; the remaining steps are the same as those in Example 2.

[0046] Comparative Example 2

[0047] The difference between Comparative Example 2 and Example 2 is that steps (1) and (3) are absent, and step (4) is modified as follows: Blend 3 parts of styrene-acrylic emulsion and 2 parts of acrylate emulsion, stir at 500 rpm for 30 min at 25°C to form a uniform mixed emulsion; the damping filler is 5 parts of mica powder and 3 parts of silica white treated with KH-550 silane coupling agent at 0.02 times the total mass of the filler, ultrasonically disperse at 40 kHz for 1 h at 60°C and then add it to the blended emulsion. The mass ratio of the filler to the blended emulsion is 1:1.5. Then, add 5% of triethylene glycol dimethacrylate, 4% of waterborne flame retardant FR713, and 0.8% of methylphenyl polyether silicone to the total mass of the emulsion in sequence, stir at 240 rpm for 30 min to obtain the waterborne damping coating; select a cylindrical roller made of 200 mm wool or chemical fiber, immerse the roller 10 mm deep into the coating, with a uniform pulling speed of 0.2 m / s, roll the roller in the same direction at a speed of 0.8 m / min to coat the waterborne damping coating on the inner layer material; dry the coated flexible damping composite material at 60°C for 10 min to finally form a film damping and noise reduction composite material; the remaining steps are the same as those in Example 2.

[0048] Comparative Example 3

[0049] The difference between Comparative Example 3 and Example 2 lies in step (1). Modify step (1) as follows: Place the carbon fiber in a plasma reaction chamber, and perform surface etching treatment for 20 min using an Ar / O2 mixed gas with a power of 200 W and a volume ratio of Ar to O2 of 4:1; perform degreasing treatment on the polyester fiber with N,N-dimethylformamide solvent, ultrasonically oscillate in a constant temperature bath at 60°C for 30 min, with a solid-liquid ratio of 1:15 and an ultrasonic power of 40 kHz; perform three-dimensional weaving on the treated fiber on a rapier loom with a warp density of 28 threads / cm and a weft density of 24 threads / cm to obtain the outer layer material; the remaining steps are the same as those in Example 2.

[0050] Comparative Example 4

[0051] The difference between Comparative Example 4 and Example 2 lies in step (2). Modify step (2) as follows: After etching basalt fiber with 3% nitric acid solution at 50°C for 1 h, mix it with polyester fiber treated by an opener at a mass ratio of 3:7. The tooth pitch of the opener is 0.5 mm and the rotation speed is 1500 rpm to obtain the inner layer material; the remaining steps are the same as those in Example 2.

[0052] Comparative Example 5

[0053] The difference between Comparative Example 5 and Example 2 is that step (4) is absent, and step (3) is changed to: after activating the inner and outer layer interfaces with He atmosphere plasma at a power of 500 W for 4 min, an epoxy-polyurethane blend adhesive is coated, where the mass ratio of epoxy resin E44 to polyurethane prepolymer is 3:1, the solid content is 45%, and it is laminated at 0.5 MPa pressure and 180 °C for 22.5 min using a hot press, and finally post-cured at 80 °C for 8 h to obtain a 1 mm thick damping and noise reduction composite material; the remaining steps are the same as those in Example 2.

[0054] Effect Example

[0055] The following Table 1 gives the performance analysis results of a flexible damping and noise reduction composite material using Examples 1 to 3 and Comparative Examples 1 to 5 of the present invention.

[0056] Table 1

[0057]

[0058]

[0059] From the comparison of the experimental data of the examples and comparative examples, it can be found that the present invention realizes the efficient absorption of broadband noise through the double-layer gradient structure design of the flexible damping and noise reduction composite material: the outer layer is formed by three-dimensional weaving of carbon fiber and polyester fiber to form a dense network, a combination of high-density support fibers and flexible fibers, and micron-sized modified paraffin phase change microcapsules are embedded. The metal oxide coating on its surface can reflect high-frequency sound waves, and at the same time, the small-aperture pores absorb medium-frequency noise through the viscous effect, and the paraffin phase change characteristics further broaden the temperature range adaptability; the inner layer constructs a loose framework with basalt fiber and polyester fiber, a combination of thick support fibers and flexible fibers, and is loaded with nano-silica aerogel. Its nano-porous network efficiently converts the low-frequency noise sound energy into heat by extending the sound wave propagation path and friction with air molecules. Combining the ultra-low density and extremely low thermal conductivity of the aerogel, while achieving lightweight, it suppresses thermal feedback to ensure that the material maintains stable damping performance in a low-temperature environment. The double-layer synergistic effect improves the sound absorption coefficient of the composite material in the full frequency band and enhances the tensile strength, combining high strength, broadband noise reduction, and temperature adaptability characteristics. The present invention can maximally reduce the noise of emergency diesel generators or power emergency vehicles in all directions, enabling power repair work not to affect the rest, work, and life of nearby residents, and playing a protective role for emergency diesel generators or power emergency vehicles in harsh environments such as wind, rain, and snow.

[0060] It is obvious to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Accordingly, all changes that fall within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claim concerned.

Claims

1. A flexible damping noise reduction composite material, wherein the composite material is prepared by three-dimensional weaving to form a composite inner and outer layer gradient structure, combined with a waterproof layer and a coating, characterized in that: The method comprises the following preparation steps: (1) placing carbon fiber in a plasma reaction chamber, and using Ar / O2 mixed gas at a power of 100-300W, with a volume ratio of Ar to O2 of 4:1, to perform surface etching for 20 minutes; performing N,N-dimethylformamide solvent degreasing treatment on polyester fiber, and ultrasonically oscillating in a 60°C constant temperature bath for 30 minutes, with a solid-liquid ratio of 1:15 and an ultrasonic power of 40kHz; after three-dimensional weaving, immersing the prefabricated fabric in an epoxy dispersion containing 1-5wt% modified paraffin phase change microcapsules, and completing microcapsule embedding at 40-60°C for 30-60 minutes under the assistance of 40kHz ultrasonic waves to obtain an outer layer material; (2) After basalt fiber was etched with 1-5% nitric acid solution at 50°C for 1 hour, it was mixed with polyester fiber treated by an opener at a mass ratio of 3:7, and the fiber matrix was prepared by the opener with a tooth pitch of 0.5 mm and a rotation speed of 1000-2000 rpm; the fiber matrix was placed in a vacuum impregnation tank and compounded with an aerogel precursor for 1-2 hours, with a vacuum degree of -0.095 MPa, and then gradient cured in a programmable temperature-controlled oven: the temperature was increased from 80°C to 120°C at a rate of 2°C / min and maintained for 1-2 hours, and then increased to 160°C for curing for 2-3 hours to prepare an inner layer material; (3) Compounding the inner layer material with the outer layer material; (4) A cylindrical roller made of 200 mm wool or chemical fiber is selected, the roller is immersed in the coating to a depth of 10 mm, the uniform pulling speed is 0.2 m / s, and the roller is rolled in the same direction at a speed of 0.8 m / min to apply the water-based damping coating to the composite material; the coated flexible damping composite material is dried at 60 °C for 10 min to finally form a coating damping noise reduction composite material.

2. The method for preparing a flexible damping noise reduction composite material according to claim 1, characterized in that: The modified paraffin phase change microcapsule preparation method in step (1) comprises: grafting stearic acid onto the paraffin molecular chain for 2 hours at 120-130°C by melt blending, wherein the mass ratio of stearic acid to paraffin is 10:1-2; then encapsulating by interfacial polymerization, using toluene-2,4-diisocyanate as the oil phase monomer and ethylenediamine as the water phase monomer, reacting for 4 hours in a system with an oil-water volume ratio of 1:3 to form microcapsules, and then performing 50-100 Al2O3 coating cycles at a substrate temperature of 120°C by atomic layer deposition equipment.

3. The method for preparing a flexible damping noise reduction composite material according to claim 2, characterized in that: The mass ratio of stearic acid to paraffin is 10:1-2.

4. The method for preparing a flexible damping noise reduction composite material according to claim 1, characterized in that: The three-dimensional weaving in step (1) is as follows: the pretreated fibers are three-dimensionally woven on a rapier loom with a warp density of 28 pretreated carbon fibers / cm and a weft density of 24 pretreated polyester fibers / cm.

5. The method for preparing a flexible damping noise reduction composite material according to claim 1, characterized in that: The aerogel precursor preparation method in step (2) is as follows: tetraethoxysilane, ethanol and deionized water are mixed in a volume ratio of 1:4:4, and the pH is adjusted to 3 with hydrochloric acid, followed by hydrolysis and polycondensation for 24 hours to obtain an aerogel precursor.

6. The method for preparing a flexible damping noise reduction composite material according to claim 1, characterized in that: The composite preparation method in step (3) is as follows: after the inner and outer layer interfaces are activated by He atmosphere plasma with a power of 500 W for 3-5 minutes, an epoxy-polyurethane blended adhesive with a solid content of 45% is coated, and the laminate is performed by a hot press at a pressure of 0.5 MPa and 180° C. for 15-30 minutes, and finally cured at 80° C. for 8 hours to obtain a composite material with a thickness of 1 mm.

7. The method for preparing a flexible damping noise reduction composite material according to claim 6, characterized in that: The mass ratio of the epoxy resin E44 to the polyurethane prepolymer is 3:

1.

8. The method for preparing a flexible damping noise reduction composite material according to claim 1, characterized in that: The preparation method of the water-based damping coating in the step (4) is as follows: 5 parts of mica powder and 3 parts of white carbon black are treated with a KH-550 silane coupling agent of 0.02 times the total mass of the filler, and then added to the blended emulsion after ultrasonic dispersion at 40kHz at 60°C for 1 hour, and then 5% of the total mass of the emulsion triethylene glycol dimethacrylate, 4% of water-based flame retardant FR713, and 0.8% of methylphenyl polyether silicone are added in sequence, and the water-based damping coating is obtained after stirring at 240rpm for 30 minutes.

9. The method for preparing a flexible damping noise reduction composite material according to claim 8, characterized in that: The mixed emulsion is prepared by blending 3 parts of styrene-acrylic emulsion and 2 parts of acrylic emulsion, stirring at 500 rpm for 30 minutes at 25° C. to form a uniform mixed emulsion.

10. The method for preparing a flexible damping noise reduction composite material according to claim 8, characterized in that: The mass ratio of the filler to the blended latex is 1:1.3-1.7.

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