Tear-resistant sound insulation cotton for electric appliances and preparation method of tear-resistant sound insulation cotton

Abstract

The invention discloses tear-resistant sound insulation cotton for electric appliances and a preparation method of the tear-resistant sound insulation cotton. The tear-resistant sound insulation cotton is prepared from the following components in parts by mass: 20-35 parts of thermoplastic polyurethane; 10 to 15 parts of basalt fiber; 8 to 12 parts of a halogen-free phosphorus-nitrogen flame retardant; 3-5 parts of a chemical foaming agent; 0.1 to 0.5 part of a waterborne polyurethane composite emulsion; and the balance of bio-based polyester. Through melt blending of thermoplastic polyurethane and bio-based polyester and combination of basalt fiber reinforcement and gradient foaming design, the comprehensive performance of the sound insulation cotton is remarkably improved; due to the high elasticity and tear resistance of thermoplastic polyurethane, the mechanical strength of bio-based polyester is effectively improved, and the tear resistance of the sound insulation cotton is improved; the chemical foaming agent forms a multi-stage pore structure with a compact surface layer and a loose inner layer through a gradient foaming technology, broadband efficient absorption can be achieved for noise of different frequency bands, and vibration noise generated when an electric appliance runs is remarkably reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sound insulation cotton preparation, in particular to a tear-resistant sound insulation cotton for electric appliances and a preparation method thereof. BACKGROUND

[0002] Traditional sound insulation cotton such as polyurethane foam has the advantages of lightweight and sound insulation, but has low mechanical strength and is prone to local tearing when subjected to long-term internal vibration or assembly stress of electric appliances, resulting in attenuation or even failure of sound insulation function. Glass fiber materials can inhibit noise propagation, but the fibers are prone to breakage and shedding, which poses a risk of polluting the internal environment of the equipment, and are harmful to human health during processing. Rubber-based materials have good tear resistance, but have high density, making it difficult to meet the lightweight design requirements of electric appliances, and have limited blocking effect on medium and high frequency noise, which requires a multi-layer composite structure to compensate for performance defects, but such a composite process often causes interlayer peeling problems due to insufficient interfacial bonding force.

[0003] In terms of sound insulation cotton preparation process, the uniformity of the pores of the finished product produced by traditional technology is difficult to control, resulting in fluctuations in sound insulation performance; when using adhesive to composite multiple layers of materials, flammable components are easily introduced or the flexibility of the material is reduced, affecting the safety and assembly adaptability of electric appliances.

[0004] In addition, some traditional processes require multiple coatings of flame-retardant or waterproof coatings, which is a tedious process with high energy consumption, and the interface between the coating and the substrate is not stable enough, and is prone to peeling and failure after long-term use. In terms of environmental protection, most materials rely on petroleum-based polymers, which are difficult to degrade and may release harmful substances during production. SUMMARY

[0005] The existing problems in the prior art are that the tear resistance and sound insulation performance of traditional sound insulation cotton materials are difficult to optimize, the environmental protection and stability are insufficient, resulting in unbalanced comprehensive performance and the inability to meet the lightweight, high reliability and environmentally friendly requirements of electric appliance sound insulation cotton. In view of the above technical problems, the present application provides a tear-resistant sound insulation cotton for electric appliances and a preparation method thereof.

[0006] The technical scheme of the present application is: a tear-resistant sound insulation cotton for electric appliances, which is composed of the following components in mass fraction: thermoplastic polyurethane: 20-35 parts; basalt fiber: 10-15 parts; halogen-free phosphorus-nitrogen flame retardant: 8-12 parts; chemical foaming agent: 3-5 parts; water-based polyurethane composite emulsion: 0.1-0.5 parts; biobased polyester: the balance.

[0007] Description: After basalt fiber is surface modified by silane coupling agent, the interfacial bonding strength with resin matrix is greatly improved, further improving the material's ability to resist crack propagation, while also avoiding the influence of local fiber slippage on sound insulation effect.

[0008] Further, the basalt fiber has a length of 3-5 mm and a diameter of 8-12 μm.

[0009] Description: By limiting the length and diameter of the basalt fiber, uniform distribution and effective stress transfer of the fiber in the resin matrix can be achieved; the 3-5 mm long fiber can form a continuous reinforcing network, avoiding the defects of short fiber migration and agglomeration, and also ensuring the material to maintain fluidity during processing; the 8-12 μm diameter fiber has high specific surface area and flexibility, and after surface modification, the interfacial bonding strength with bio-based polyester and thermoplastic polyurethane is significantly improved, avoiding the delamination or performance degradation of sound insulation cotton caused by fiber shedding.

[0010] Further, the bio-based polyester is polylactic acid or polybutylene succinate.

[0011] Description: Both polylactic acid and polybutylene succinate are biodegradable bio-based polyesters, and their glass transition temperature and melting characteristics are complementary to thermoplastic polyurethane; the rigid backbone of polylactic acid can increase the overall stiffness of the sound insulation cotton, while the flexibility of polybutylene succinate enhances the material's fatigue resistance in a vibrating environment; the micro-phase separation structure formed by blending the two with thermoplastic polyurethane not only retains the environmental protection characteristics of bio-based materials, but also solves the mechanical performance deficiency of single bio-based polyester.

[0012] Further, the halogen-free phosphorus-nitrogen flame retardant is compounded by ammonium polyphosphate and melamine polyphosphate at a mass ratio of 3-4:1.

[0013] Description: The proportionally compounded flame retardant can achieve the synergistic effect of gas phase and condensed phase flame retardation; the polyphosphoric acid generated by the thermal decomposition of ammonium polyphosphate promotes the formation of a carbon layer that covers the surface of the material to insulate oxygen, while the melamine polyphosphate decomposes to release inert gas to dilute combustible gas; when the mass ratio of the two is 3-4:1, the dense carbon layer formed has the best density, the flame retardant efficiency reaches UL94 V-0 level, and the impact on the material's mechanical properties is minimal.

[0014] Further, the chemical foaming agent is compounded by azodicarbonamide and sodium bicarbonate at a mass ratio of 1.5-2:1.

[0015] Explanation: Azodicarbonamide decomposes at high temperatures to release nitrogen gas, forming the main pores, while sodium bicarbonate decomposes at medium and low temperatures to produce carbon dioxide, which assists in the formation of micropores. When the two are compounded in a ratio of 1.5-2:1, the decomposition temperature range matches the processing temperature, forming a gradient pore structure with small pores on the surface and large pores in the inner layer, thus optimizing the broadband sound insulation effect. This ratio also avoids the pore merging defect caused by excessive foaming agent, ensuring the uniformity of material density and mechanical strength.

[0016] Furthermore, the waterborne polyurethane composite emulsion is composed of 1-3 wt% nano-silica, 17-27 wt% waterborne polyurethane resin, 0.1-1 wt% additives, and the balance being water; the additives are at least one of dispersant and defoamer.

[0017] Description: Nano-silica enhances the surface hardness and wear resistance of the coating; water-based polyurethane resin, as the film-forming matrix, imparts flexibility and adhesion to the substrate; trace additives maintain emulsion stability and eliminate spraying bubbles; the water ratio optimizes the application viscosity and environmental friendliness, forming a continuous and dense functional coating that blocks the erosion of the substrate by the humid and hot environment and extends the service life of the sound insulation cotton.

[0018] Furthermore, the preparation method of the tear-resistant sound-insulating cotton for electrical appliances includes the following steps: S1, Basalt Fiber Pretreatment The basalt fiber was immersed in a silane coupling agent ethanol solution with a mass concentration of 3-5%, ultrasonically dispersed at room temperature with a power of 200-300W for 15-20 minutes, and then dried at a temperature of 60-80℃ to obtain pretreated fiber material. S2, Preparation of blended foaming matrix The bio-based polyester, thermoplastic polyurethane, halogen-free phosphorus and nitrogen flame retardant, and chemical foaming agent are added to a high-speed mixer according to the above ratio and stirred at a rate of 500-800 r / min for 10-15 min. Then, the mixture is melt-blended through a twin-screw extruder at a screw speed of 180-220 r / min. After extrusion and foaming, the mixture is water-cooled and pelletized to obtain porous composite masterbatch. S3, gradient foaming molding The porous composite masterbatch described in S2 is mixed with the pretreated fiber material described in S1 and put into a mold for two-stage hot pressing. First, it is pressed at a temperature of 120-130℃ and a pressure of 5-8MPa for 2-3 minutes; then it is pressed at a temperature of 140-150℃ and a pressure of 2-4MPa for 4-6 minutes to obtain a gradient pore substrate. The preheating temperature of the mold is 100-110℃; the interval between the two stages of hot pressing is 0.1-10s. S4, Surface strengthening treatment The gradient porous substrate described in S3 is immersed in a 2-4% (w / w) aqueous solution of polyethyleneimine and reacted at 50-60°C for 1-2 hours. After removal, it is dried at 80-90°C. Subsequently, the aqueous polyurethane composite emulsion is sprayed on and cured at 100-110°C for 20-30 minutes to obtain tear-resistant sound insulation cotton.

[0019] Note: Surface functionalization is completed through a one-step impregnation and spraying process. While improving the material's resistance to damp heat aging, it avoids the increased energy consumption and interface peeling risks caused by traditional multi-layer coating, and maintains the air permeability of the pore structure.

[0020] Furthermore, in S2, the temperature of the feeding section of the twin-screw extruder is 150-160℃, the temperature of the melting section is 165-175℃, and the temperature of the homogenization section is 170-180℃; the water cooling temperature is 25-30℃, and the water cooling time is 30-45s.

[0021] Explanation: Staged temperature control ensures synergistic plasticization of bio-based polyester and thermoplastic polyurethane. The feeding section temperature prevents premature softening of raw materials, which can lead to feeding blockage. The melting section temperature allows the thermoplastic polyurethane to fully melt and form an elastic network. The homogenization section temperature optimizes melt flow to uniformly coat basalt fibers. Water cooling at 25-30℃ rapidly sets the foam structure, avoiding cell merging or collapse at high temperatures and ensuring uniform pore distribution and matrix mechanical properties.

[0022] The beneficial effects of this invention are: This invention achieves a significant improvement in the overall performance of sound insulation cotton through the melt blending of thermoplastic polyurethane and bio-based polyester, combined with basalt fiber reinforcement and gradient foaming design. The high elasticity and tear resistance of thermoplastic polyurethane effectively improve the mechanical strength of bio-based polyester, enabling the material to maintain structural integrity under long-term vibration or stress, avoiding the sound insulation failure problem caused by local tearing in traditional sound insulation cotton. The compatibility optimization of halogen-free phosphorus and nitrogen flame retardants with bio-based polyester endows the material with stable flame retardant properties, meeting electrical safety standards and eliminating the risk of toxic gas release. The chemical foaming agent forms a multi-level porous structure with dense micropores on the surface and loose macropores in the inner layer through a gradient foaming process. Staged hot pressing can control the pore structure to make it uniform, achieving wide-band and efficient absorption of noise in different frequency bands, significantly reducing the mid-to-low frequency vibration noise during the operation of electrical appliances. As the main matrix material, bio-based polyester is renewable and biodegradable, reducing environmental impact. Detailed Implementation

[0023] To further illustrate the methods and effects of this invention, the technical solution of this invention will be clearly and completely described below in conjunction with experiments.

[0024] Example 1: An electrical appliance tear-resistant sound insulation cotton is composed of the following components in parts by weight: Thermoplastic polyurethane: 27.5 parts; Basalt fiber: 12.5 parts; Halogen-free phosphorus-nitrogen flame retardant: 10 parts; Chemical foaming agent: 4 parts; Waterborne polyurethane composite emulsion: 0.3 parts; Bio-based polyester: Balance; The basalt fiber has a length of 3.5-4.5 mm and a diameter of 10-11 μm; the bio-based polyester is polylactic acid; the halogen-free phosphorus-nitrogen flame retardant is a compound of ammonium polyphosphate and melamine polyphosphate in a mass ratio of 3.5:1; the chemical foaming agent is a compound of azodicarbonamide and sodium bicarbonate in a mass ratio of 1.8:1. The preparation method of the tear-resistant sound insulation cotton for electrical appliances includes the following steps: S1, Basalt Fiber Pretreatment The basalt fiber was immersed in a 4% (w / w) silane coupling agent ethanol solution, ultrasonically dispersed at 250W for 18 minutes at room temperature, and then dried at 70℃ to obtain pretreated fiber material. S2, Preparation of blended foaming matrix The bio-based polyester, thermoplastic polyurethane, halogen-free phosphorus and nitrogen flame retardant and chemical foaming agent are added to a high-speed mixer according to the above ratio and stirred at a rate of 650 r / min for 12.5 min; then melt-blended through a twin-screw extruder at a screw speed of 200 r / min, and after extrusion foaming, water-cooled pelletizing is performed to obtain porous composite masterbatch. The twin-screw extruder has a feed section temperature of 155°C, a melting section temperature of 170°C, and a homogenization section temperature of 175°C; the water cooling temperature is 22.5°C, and the water cooling time is 40 seconds. S3, gradient foaming molding The porous composite masterbatch described in S2 is mixed with the pretreated fiber material described in S1 and put into a mold for two-stage hot pressing. First, it is pressed at a temperature of 125°C and a pressure of 6.5MPa for 2.5 minutes; then it is pressed at a temperature of 145°C and a pressure of 3MPa for 5 minutes to obtain a gradient pore substrate. The preheating temperature of the mold is 105℃; the interval between the two-stage hot pressing is 5s. S4, Surface strengthening treatment The gradient porous substrate described in S3 is immersed in a 3% (w / w) aqueous solution of polyethyleneimine and reacted at 55°C for 1.5 h. After removal, it is dried at 85°C. Then, the aqueous polyurethane composite emulsion is uniformly sprayed and cured at 105°C for 25 min to obtain tear-resistant sound insulation cotton. The aqueous polyurethane composite emulsion is composed of 2 wt% nano silica, 22 wt% aqueous polyurethane resin, 0.5 wt% additives, and the balance being water; the additives are commercially available BYK-2012 polycarboxylate ammonium salt dispersants.

[0025] Example 2: This example is basically the same as Example 1, except that an electrical appliance tear-resistant sound insulation cotton is composed of the following components in parts by weight: Thermoplastic polyurethane: 20 parts; Basalt fiber: 10 parts; Halogen-free phosphorus-nitrogen flame retardant: 8 parts; Chemical foaming agent: 3 parts; Waterborne polyurethane composite emulsion: 0.1 parts; Bio-based polyester: Balance.

[0026] Example 3: This example is basically the same as Example 1, except that an electrical appliance tear-resistant sound insulation cotton is composed of the following components in parts by weight: Thermoplastic polyurethane: 35 parts; Basalt fiber: 15 parts; Halogen-free phosphorus-nitrogen flame retardant: 12 parts; Chemical foaming agent: 5 parts; Waterborne polyurethane composite emulsion: 0.5 parts; Bio-based polyester: Balance.

[0027] Example 4: This example is basically the same as Example 1, except that the basalt fiber is 3-4 mm in length and 8-9 μm in diameter; the halogen-free phosphorus-nitrogen flame retardant is compounded from ammonium polyphosphate and melamine polyphosphate in a mass ratio of 3:1; and the chemical foaming agent is compounded from azodicarbonamide and sodium bicarbonate in a mass ratio of 1.5:1.

[0028] Example 5: This example is basically the same as Example 1, except that the basalt fiber is 4-5 mm in length and 11-12 μm in diameter; the halogen-free phosphorus-nitrogen flame retardant is compounded from ammonium polyphosphate and melamine polyphosphate in a mass ratio of 4:1; and the chemical foaming agent is compounded from azodicarbonamide and sodium bicarbonate in a mass ratio of 2:1.

[0029] Example 6: This example is basically the same as Example 1, except that the basalt fiber is immersed in a 3% (w / w) silane coupling agent ethanol solution, ultrasonically dispersed at 200W for 15 minutes at room temperature, and then dried at 60℃ to obtain pretreated fiber material; the porosity of the sound insulation cotton in this example is 75%, with 65% of the surface pores being 50-80μm and 35% of the inner pores being 200-250μm.

[0030] Example 7: This example is basically the same as Example 1, except that the basalt fiber is immersed in a 5% silane coupling agent ethanol solution, ultrasonically dispersed at 300W power for 20 minutes at room temperature, and then dried at 80℃ to obtain pretreated fiber material.

[0031] Example 8: This example is basically the same as Example 1, except that the bio-based polyester, thermoplastic polyurethane, halogen-free phosphorus and nitrogen flame retardant and chemical foaming agent are added into a high-speed mixer according to the above ratio and stirred at a rate of 500 r / min for 10 min; then melt-blended through a twin-screw extruder at a screw speed of 180 r / min, and after extrusion foaming, it is water-cooled and pelletized to obtain porous composite masterbatch; The twin-screw extruder has a feed section temperature of 150°C, a melting section temperature of 165°C, and a homogenization section temperature of 170°C; the water cooling temperature is 25°C, and the water cooling time is 30 seconds.

[0032] Example 9: This example is basically the same as Example 1, except that the bio-based polyester, thermoplastic polyurethane, halogen-free phosphorus and nitrogen flame retardant and chemical foaming agent are added into a high-speed mixer according to the above ratio and stirred at a rate of 800 r / min for 15 min; then melt-blended through a twin-screw extruder at a screw speed of 220 r / min, and after extrusion foaming, it is water-cooled and pelletized to obtain porous composite masterbatch; The twin-screw extruder has a feed section temperature of 160°C, a melting section temperature of 175°C, and a homogenization section temperature of 180°C; the water cooling temperature is 30°C, and the water cooling time is 45 seconds.

[0033] Example 10: This example is basically the same as Example 1, except that the porous composite masterbatch described in S2 is mixed with the pretreated fiber material described in S1 and put into a mold for two-stage hot pressing. First, it is pressed at a temperature of 120°C and a pressure of 5MPa for 2 minutes; then it is pressed at a temperature of 140°C and a pressure of 2MPa for 4 minutes to obtain a gradient pore substrate. The preheating temperature of the mold is 100°C. The interval between the two stages of hot pressing is 0.1s.

[0034] Example 11: This example is basically the same as Example 1, except that the porous composite masterbatch described in S2 is mixed with the pretreated fiber material described in S1 and put into a mold for two-stage hot pressing. First, it is pressed at a temperature of 130°C and a pressure of 8MPa for 3 minutes; then it is pressed at a temperature of 150°C and a pressure of 4MPa for 6 minutes to obtain a gradient pore substrate. The preheating temperature of the mold is 110°C. The interval between the two stages of hot pressing is 10 seconds.

[0035] Example 12: This example is basically the same as Example 1, except that the gradient pore substrate described in S3 is immersed in a 2% (w / w) polyethyleneimine aqueous solution and reacted at 50°C for 1 hour. After being removed, it is dried at 80°C. Then, the aqueous polyurethane composite emulsion is uniformly sprayed and cured at 100°C for 20 minutes to obtain tear-resistant sound insulation cotton. The aqueous polyurethane composite emulsion consists of 1 wt% nano silica, 17 wt% aqueous polyurethane resin, 0.1 wt% additives, and the balance being water.

[0036] Example 13: This example is basically the same as Example 1, except that the gradient pore substrate described in S3 is immersed in a 4% (w / w) polyethyleneimine aqueous solution and reacted at 60°C for 2 hours. After being removed, it is dried at 90°C. Then, the aqueous polyurethane composite emulsion is uniformly sprayed and cured at 110°C for 30 minutes to obtain tear-resistant sound insulation cotton. The waterborne polyurethane composite emulsion consists of 3 wt% nano silica, 27 wt% waterborne polyurethane resin, 1 wt% additives, and the balance being water; the additive is Tego Foamex 825, a waterborne non-silicone defoamer produced by Evonik Industries.

[0037] Example 14: This example is basically the same as Example 1, except that the bio-based polyester is polybutylene succinate.

[0038] Comparative Example 1: Referring to Example 1, an electrical appliance tear-resistant sound insulation cotton is composed of the following components in parts by weight: Thermoplastic polyurethane: 15 parts; Basalt fiber: 5 parts; Halogen-free phosphorus-nitrogen flame retardant: 7 parts; Chemical foaming agent: 2 parts; Waterborne polyurethane composite emulsion: 0.05 parts; Bio-based polyester: Balance.

[0039] Comparative Example 2: Referring to Example 1, an electrical appliance tear-resistant sound insulation cotton is composed of the following components in parts by weight: Thermoplastic polyurethane: 38 parts; Basalt fiber: 16 parts; Halogen-free phosphorus-nitrogen flame retardant: 14 parts; Chemical foaming agent: 7 parts; Waterborne polyurethane composite emulsion: 1 part; Bio-based polyester: Balance.

[0040] Comparative Example 3: This example is basically the same as Example 1, except that the gradient foaming process is cancelled and a single-stage hot pressing is adopted: pressing for 5 minutes at a pressure of 8MPa and a temperature of 130℃.

[0041] Comparative Example 4: This example is basically the same as Example 1, except that the basalt fiber was not pretreated with silane coupling agent and was directly mixed with porous composite masterbatch and hot-pressed.

[0042] To investigate the sound insulation performance of the above-described embodiments and control examples, the main materials were determined according to the experimental formula, and samples were obtained for tensile strength, sound insulation, and density tests. The tests were conducted according to the standards ASTM D638, ISO 10140-2, and ASTM D792, respectively. The test results are shown in Table 1. The specific investigation is as follows: Table 1 Performance test results of sound insulation cotton samples from Examples 1-14 and Control Examples 1-4

[0043] 1. Investigate the influence of ingredient parameters on the performance of sound insulation cotton: As shown in Table 1, in Examples 1 to 3, as the amount of thermoplastic polyurethane increased from 20 parts to 35 parts, the tensile strength increased from 4.6 MPa to 5.8 MPa, but the density increased from 0.19 g / cm³ to 0.24 g / cm³. The highly elastic network of thermoplastic polyurethane effectively inhibited the propagation of matrix cracks, but excessive addition hindered the uniform decomposition of the foaming agent, leading to an increase in density. In Control Example 1, with only 15 parts of thermoplastic polyurethane, the tensile strength dropped sharply to 3.1 MPa, and the density reached 0.28 g / cm³, verifying the dual necessity of thermoplastic polyurethane for toughening and lightweighting.

[0044] 2. Investigate the effect of gradient foaming process on the performance of sound insulation cotton: As shown in Table 1, Example 1, through two-stage hot pressing, forms gradient pores, achieving a sound insulation of 31 dB with a density of only 0.21 g / cm³. In contrast, Comparative Example 3, using single-stage high-pressure pressing, shows a decrease in sound insulation to 23 dB and an increase in density to 0.27 g / cm³, indicating that single-stage high pressure causes pore collapse, failing to form a synergistic sound-absorbing structure of dense micropores on the surface and loose macropores in the inner layer. Example 10, with a sound insulation of 27 dB, further demonstrates that an excessively low pressure gradient weakens low-frequency sound absorption efficiency.

[0045] 3. Investigate the effect of basalt fiber pretreatment on the performance of sound insulation cotton: As shown in Table 1, the tensile strength of the pretreated fiber in Example 1 was 5.2 MPa, while the tensile strength of the untreated control example 4 was only 3.6 MPa. It can be seen that the silane coupling agent enhanced the interfacial bonding force between the fiber and the matrix through chemical bonding, avoiding interfacial delamination caused by stress concentration. The sound insulation of control example 4 was 20 dB, which was also significantly lower than the 31 dB of example 1, indicating that the uneven dispersion of the untreated fiber may have affected the continuity of the gradient pores.

[0046] 4. Investigating the effect of different types of bio-based polyester on the performance of sound insulation cotton: As shown in Table 1, the tensile strengths of Example 1 and Example 14 are 5.2 MPa and 5.1 MPa, respectively, with similar sound insulation levels of 31 dB and 30 dB. Example 1 uses polylactic acid (PLA), whose rigid framework is more suitable for high-frequency sound insulation, while the polybutylene succinate (PBS) of Example 14 exhibits better flexibility and anti-aging properties in humid and hot environments. Both can be used as matrix materials, but the choice should be based on the operating environment of the electrical appliance.

[0047] 5. Investigate the effects of parameters of halogen-free phosphorus-nitrogen flame retardants and chemical foaming agents on the performance of sound insulation cotton: As shown in Table 1, the combination of halogen-free phosphorus-nitrogen flame retardant and chemical foaming agent in Example 1 achieved a balance between high sound insulation and flame retardancy, with good sound insulation. The sound insulation of Control Example 2 was only 25dB, and the density was as high as 0.31g / cm³. It can be seen that excessive flame retardant will interfere with the decomposition of foaming agent and destroy the pore structure. Compared with Control Examples 1-2, the sample prepared using the process parameters within the range of Examples 1-3 had the best effect.

Claims

1. A tear-resistant sound-insulating cotton for electrical appliances, characterized in that, It consists of the following components in parts by mass: Thermoplastic polyurethane: 20-35 parts; Basalt fiber: 10-15 parts; Halogen-free phosphorus-nitrogen flame retardant: 8-12 parts; Chemical foaming agent: 3-5 parts; Waterborne polyurethane composite emulsion: 0.1-0.5 parts; Bio-based polyester: Balance.

2. The tear-resistant sound insulation cotton for electrical appliances according to claim 1, characterized in that, The basalt fibers are 3-5 mm in length and 8-12 μm in diameter.

3. The tear-resistant sound insulation cotton for electrical appliances according to claim 1, characterized in that, The bio-based polyester is polylactic acid or polybutylene succinate.

4. The tear-resistant sound insulation cotton for electrical appliances according to claim 1, characterized in that, The halogen-free phosphorus-nitrogen flame retardant is a compound of ammonium polyphosphate and melamine polyphosphate in a mass ratio of 3-4:

1.

5. The tear-resistant sound insulation cotton for electrical appliances according to claim 1, characterized in that, The chemical foaming agent is a compound of azodicarbonamide and sodium bicarbonate in a mass ratio of 1.5-2:

1.

6. The method for preparing tear-resistant sound-insulating cotton for electrical appliances according to claim 1, characterized in that, The waterborne polyurethane composite emulsion is composed of 1-3 wt% nano-silica, 17-27 wt% waterborne polyurethane resin, 0.1-1 wt% additives, and the balance being water; the additives are at least one of dispersant and defoamer.

7. The method for preparing the tear-resistant sound-insulating cotton for electrical appliances according to claim 1, characterized in that, Includes the following steps: S1, Basalt Fiber Pretreatment The basalt fiber was immersed in a silane coupling agent ethanol solution with a mass concentration of 3-5%, ultrasonically dispersed at room temperature with a power of 200-300W for 15-20 minutes, and then dried at a temperature of 60-80℃ to obtain pretreated fiber material. S2, Preparation of blended foaming matrix The bio-based polyester, thermoplastic polyurethane, halogen-free phosphorus and nitrogen flame retardant, and chemical foaming agent are added to a high-speed mixer according to the above ratio and stirred at a rate of 500-800 r / min for 10-15 min. Then, the mixture is melt-blended through a twin-screw extruder at a screw speed of 180-220 r / min. After extrusion and foaming, the mixture is water-cooled and pelletized to obtain porous composite masterbatch. S3, gradient foaming molding The porous composite masterbatch described in S2 is mixed with the pretreated fiber material described in S1 and put into a mold for two-stage hot pressing. First, it is pressed at a temperature of 120-130℃ and a pressure of 5-8MPa for 2-3 minutes; then it is pressed at a temperature of 140-150℃ and a pressure of 2-4MPa for 4-6 minutes to obtain a gradient pore substrate. The preheating temperature of the mold is 100-110℃; the interval between the two stages of hot pressing is 0.1-10s. S4, Surface strengthening treatment The gradient porous substrate described in S3 is immersed in a 2-4% (w / w) aqueous solution of polyethyleneimine and reacted at 50-60°C for 1-2 hours. After removal, it is dried at 80-90°C. Subsequently, the aqueous polyurethane composite emulsion is sprayed on and cured at 100-110°C for 20-30 minutes to obtain tear-resistant sound insulation cotton.

8. The method for preparing tear-resistant sound-insulating cotton for electrical appliances according to claim 7, characterized in that, The twin-screw extruder described in S2 has a feed section temperature of 150-160℃, a melting section temperature of 165-175℃, and a homogenization section temperature of 170-180℃; the water cooling temperature is 25-30℃, and the water cooling time is 30-45s.

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