Sound-absorbing block, its manufacturing method, and applications

Abstract

The present invention provides a sound-absorbing block, a manufacturing method thereof, and applications thereof. [Solution] The sound-absorbing material block comprises a three-dimensional open-pore foam, sound-absorbing material powder, an adhesive, a gelling agent and a crosslinking agent, and the gelling agent bonds the sound-absorbing material powder to each other and connects them to the three-dimensional open-pore foam by means of the crosslinking agent and adhesive, and depending on the mass of the sound-absorbing material powder, the gelling agent accounts for 1-5 wt% of the sound-absorbing material powder, the adhesive accounts for 1-8 wt% of the sound-absorbing material powder, and depending on the mass of the gelling agent, the crosslinking agent accounts for 1-10 wt% of the gelling agent. The sound-absorbing material block of the present invention can reduce the amount of adhesive added, and significantly improves the sound-absorbing performance and strength of the sound-absorbing material block.

Description

[Technical Field]

[0001] The present invention relates to the field of composite materials, and in particular to a sound-absorbing block and its manufacturing method and application. [Background technology]

[0002] Demands for audio quality in various mobile devices are increasing. To improve the audio quality of mobile devices, the current approach in the field is to fill the rear cavity of the speaker with sound-absorbing material and increase the volume of the virtual rear cavity, thereby improving the audio quality.

[0003] Typically, sound-absorbing powder is bonded into a spherical shape with an adhesive to ensure excellent sound absorption performance. However, collisions between sound-absorbing particles can cause degradation, such as powder falling off or shattering. To avoid this, it is necessary to increase the adhesive's occupancy rate in the sound-absorbing material. However, increasing the adhesive content leads to the blockage of a large number of mesopores or pores in the sound-absorbing particles, significantly reducing sound absorption performance. Therefore, from the perspectives of both performance and strength, the adhesive content in the sound-absorbing material particles must be kept within a certain range, but this also limits the improvement of the sound-absorbing material's performance.

[0004] In order to increase the strength of sound-absorbing materials, reduce the risk of sound-absorbing particle fracture, and simultaneously improve sound absorption performance, methods have generally been adopted in this field, such as forming sound-absorbing material powder into blocks or directly molding it in a rear cavity, which are simple processes and reduce the risk of fracture due to mutual collisions.However, such sound-absorbing material blocks often have poor performance, with the material powder easily clumping together and problems such as breakage of the material block and powder falling off can occur.

[0005] Therefore, providing a high-performance, high-strength sound-absorbing block and a method for manufacturing the same is an urgent problem to be solved in the art. Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide a sound-absorbing material block that can reduce the amount of adhesive added and can increase the strength and performance of the sound-absorbing material block. [Means for solving the problem]

[0007] The technical solution of the present invention is as follows: the sound-absorbing block includes three-dimensional open-pore foam, sound-absorbing powder, adhesive, gelling agent, and cross-linking agent, the gelling agent uses the cross-linking agent and adhesive to bond the sound-absorbing powder to each other and connect them to the three-dimensional open-pore foam, the gelling agent accounts for 1-5 wt% of the sound-absorbing powder, the adhesive accounts for 1-8 wt% of the sound-absorbing powder, and the cross-linking agent accounts for 1-10 wt% of the gelling agent, depending on the mass of the sound-absorbing powder.

[0008] Preferably, the cross-linking agent is one or more of N,N'-methylenebisacrylamide, boric acid, calcium chloride, aluminum chloride.

[0009] Preferably, the three-dimensional open-pore foam has a porosity of more than 60% and a density of 10 to 100 mg / cm. 3 is.

[0010] Preferably, the three-dimensional open-pore foam is a melamine foam or a polyurethane foam.

[0011] Preferably, the sound-absorbing powder is a zeolite material consisting of one or more of MFI molecular sieves, MEL molecular sieves and FER molecular sieves, each having a silicon-aluminum ratio of more than 100 and a particle size of less than 10 μm.

[0012] Preferably, the adhesive is one or more of polyacrylic acid ester, styrene butadiene latex, polystyrene methyl acrylate, polystyrene acetate ester, polyurethane resin, polyethyl vinyl acetate salt.

[0013] Preferably, the gelling agent is one or more of sodium hydroxymethylcellulose, sodium alginate, chitosan, sodium polyacrylate, polyacrylamide, gelatin, polyvinyl alcohol.

[0014] Meanwhile, the present invention further provides a method for manufacturing the sound-absorbing material block of the present invention, the method comprising: The following steps S1 to S5 are included. S1: Mixing sound-absorbing powder, gelling agent, adhesive and solvent together to form slurry A; S2: Add a crosslinking agent to the slurry A and stir uniformly to obtain a slurry B. S3: Adding the slurry B to the three-dimensional open-pore foam and aging it to form a gel in the three-dimensional open-pore foam; S4: Drying the aged sample; S5: The dried sample is dehydrated to obtain the sound-absorbing material block.

[0015] Preferably, the solvent is one or more of water, methanol, ethanol, butanol and ethyl acetate.

[0016] Accordingly, the present application further provides a speaker including a housing having an accommodating space, a sound-producing unit disposed within the housing, and a rear cavity surrounded by the sound-producing unit and the housing, the rear cavity being filled with the sound-absorbing material block of the present invention.

[0017] According to the method of the present invention, in step S1 of forming slurry A, the sound-absorbing material powder, gelling agent, adhesive, and solvent can be blended using any method known in the art. Blending is preferably carried out at room temperature under stirring, and more preferably while applying ultrasonic waves. The blending time is not particularly limited as long as uniform mixing is achieved, and generally, uniform mixing can be achieved within 30 to 120 minutes.

[0018] According to the method of the present invention, in step S2 of forming slurry B, the stirring time is not particularly limited as long as uniform mixing is achieved. Generally, uniform mixing can be achieved within 5 to 30 minutes, and the stirring is preferably carried out at room temperature.

[0019] According to the method of the present invention, in the gel formation step S3, slurry B can be added to the three-dimensional open-cell foam using any method known in the art, preferably by dropwise addition, and aging at room temperature is preferred, with the aging time generally being 30 to 120 minutes.

[0020] According to the method of the present invention, in the drying step S4, drying may be performed by any method known in the art, and freeze-drying is preferred.

[0021] According to the method of the present invention, in the dehydration step S5, dehydration may be performed by any method known in the art, and dehydration by baking is preferred, with the baking temperature generally being 50 to 100°C and the baking time generally being 1 to 6 hours.

[0022] The present application also relates to the application of the sound-absorbing material block of the present invention to speakers in electronic devices, including but not limited to smartphones, watches, tablets, smart speakers, notebooks, televisions, and automobiles.

[0023] When the sound-absorbing material block of the present invention is applied to a speaker, the three-dimensional open-pore foam can first be cut into a shape that fits the rear cavity of the speaker, such as a sphere, ellipsoid, tetrahedron, hexahedron, or any other shape that fits the rear cavity of the speaker. [Effects of the Invention]

[0024] Compared with the prior art, the advantages of the present invention are as follows:

[0025] First, by adding a gelling agent and a cross-linking agent during sample production to form a cross-linked structure, the amount of adhesive added can be reduced, which prevents the holes on the surface of the sound-absorbing powder material from being blocked and improves sound-absorbing performance.

[0026] Secondly, the dual action of the cross-linked structure of the gelling agent and the foam skeleton can significantly increase the strength of the sample at low adhesive content.

[0027] Furthermore, the gelling agent disperses the sound-absorbing powder uniformly in the solvent, making it less likely to aggregate and preventing settling even when left standing for a long period of time, which is advantageous for industrial production.

[0028] Finally, the present invention has a simple manufacturing process, and can improve the sound absorption performance and strength of the sound absorber block, as well as improve the assembly efficiency of the sound absorber.

[0029] The features of the present invention, as well as other objects and advantages thereof, will become apparent from the following description of the invention taken in conjunction with the drawings. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1 is a SEM image of the surface of a sound-absorbing block according to Example 1 of the present invention. [Figure 2] FIG. 2 is an SEM image of the sound-absorbing material block in Example 1 of the present invention, cut at a depth of 100 μm. [Figure 3] FIG. 3 is an SEM image of the sound-absorbing material block in Example 1 of the present invention, cut at a depth of 20 μm. DETAILED DESCRIPTION OF THE INVENTION

[0031] In this application, the term "room temperature" refers to an ambient temperature of 18 to 25°C.

[0032] In the present invention, a new sound-absorbing block is manufactured by using a three-dimensional open-pore foam as a holder and bonding sound-absorbing material powder to each other using a gelling agent, a cross-linking agent, and an adhesive, and connecting them to the three-dimensional open-pore foam holder. The sound-absorbing material block manufactured by the method of the present invention not only has excellent sound-absorbing performance, but also has significantly improved strength.

[0033] The present invention will be described in more detail below with reference to examples. However, the specific examples described here are for the purpose of illustrating the present invention and are not intended to limit the present invention. Manufacturing Example Example 1

[0034] In this embodiment, the sound absorbing material block is manufactured by the following steps.

[0035] 0.05 g of sodium alginate was weighed and added to 8 g of water at room temperature and stirred for 20 minutes to form a uniform and transparent aqueous sodium alginate solution. 4 g of zeolite material and 0.2 g of styrene-butadiene latex (solid content 50 wt%) were then added to the aqueous sodium alginate solution, followed by stirring and ultrasonic treatment for 20 minutes to obtain Slurry A. The zeolite material was one or more of MFI molecular sieves, MEL molecular sieves, and FER molecular sieves, each with a silicon-aluminum ratio greater than 100 and a particle size less than 10 μm.

[0036] 0.005 g of calcium chloride was added to Slurry A, and the mixture was stirred at room temperature for 10 minutes to obtain Slurry B.

[0037] Slurry B is sucked up and dropped onto a melamine foam material, and aged at room temperature for 60 minutes. The density of the melamine foam is 10 to 100 mg / cm. 3 and the porosity is greater than 60%.

[0038] The aged sample is then freeze-dried using a freeze-dryer.

[0039] After the freeze-drying process is complete, the obtained sample is placed in an 80°C environment and baked for 2 hours to dehydrate it, thereby obtaining the desired sound-absorbing material block.

[0040] The surface and cross section of the obtained sound-absorbing block were scanned using a scanning electron microscope. The SEM image of the surface of the sound-absorbing block is shown in Figure 1, and the SEM images of the cross section are shown in Figures 2 and 3. As can be seen from the figures, the zeolite material powder in the melamine foam adheres to each other, forming a gel bridge structure that connects to the melamine foam holder. Example 2

[0041] In this embodiment, the sound absorbing material block is manufactured by the following steps.

[0042] 0.08 g of polyacrylamide was weighed and added to 8 g of water at room temperature and stirred for 20 minutes to form a uniform and transparent aqueous polyacrylamide solution. 5 g of zeolite material and 0.15 g of polystyrene acetate (solid content 50 wt%) were then added to the aqueous polyacrylamide solution, followed by stirring and ultrasonic treatment for 20 minutes to obtain Slurry A. The zeolite material was one or more of MFI molecular sieves, MEL molecular sieves, and FER molecular sieves, each with a silicon-to-aluminum ratio greater than 100 and a particle size less than 10 μm.

[0043] 0.005 g of N,N'-methylenebisacrylamide was added to Slurry A, and the mixture was stirred at room temperature for 10 minutes to obtain Slurry B.

[0044] Slurry B is sucked up and dropped onto a melamine foam material, and aged at room temperature for 60 minutes. The density of the melamine foam is 10 to 100 mg / cm. 3 and the porosity is greater than 60%.

[0045] The aged sample is then freeze-dried using a freeze-dryer.

[0046] After the freeze-drying process is complete, the obtained sample is placed in an 80°C environment and baked for 2 hours to dehydrate it, thereby obtaining the desired sound-absorbing material block.

[0047] The surface and cross section of the obtained sound-absorbing block were scanned by a scanning electron microscope, and the obtained SEM images were similar to those in Example 1. As can be clearly seen from the images, the zeolite material powders in the melamine foam were bonded to each other, forming a gel bridge structure that connected to the melamine foam holder. Example 3

[0048] In this embodiment, the sound absorbing material block is manufactured in the following steps.

[0049] 0.1 g of sodium polyacrylate was weighed and added to 8 g of water at room temperature and stirred for 20 minutes to form a uniform and transparent aqueous sodium polyacrylate solution, and then 4.5 g of zeolite material and 0.3 g of polyacrylic acid ester (solid content 50 wt%) were added to the aqueous sodium polyacrylate solution, followed by stirring and ultrasonic treatment for 40 minutes to obtain Slurry A. The zeolite material was one or more of MFI molecular sieves, MEL molecular sieves, and FER molecular sieves, each with a silicon-to-aluminum ratio greater than 100 and a particle size less than 10 μm.

[0050] 0.008 g of N,N'-methylenebisacrylamide was added to Slurry A, and the mixture was stirred at room temperature for 10 minutes to obtain Slurry B.

[0051] Slurry B is sucked up and dropped onto a polyurethane foam material, and aged at room temperature for 60 minutes. The density of the polyurethane foam is 10 to 100 mg / cm. 3 and the porosity is greater than 60%.

[0052] The aged sample is then freeze-dried using a freeze-dryer.

[0053] After the freeze-drying process is complete, the obtained sample is placed in an 80°C environment and baked for 2 hours to dehydrate it, thereby obtaining the desired sound-absorbing material block.

[0054] The surface and cross section of the obtained sound-absorbing block were scanned by a scanning electron microscope, and the obtained SEM images were similar to those in Example 1. As can be clearly seen from the images, the zeolite material powders adhered to each other in the polyurethane foam, forming a gel bridge structure that was connected to the polyurethane foam holder. Comparative Example 1

[0055] In this comparative example, the sound-absorbing material block is manufactured by the following steps.

[0056] 0.05 g of sodium alginate was weighed and added to 8 g of water at room temperature and stirred for 20 minutes to form a uniform and transparent aqueous sodium alginate solution. 4 g of zeolite material and 0.1 g of styrene-butadiene latex (solid content 50 wt%) were then added to the aqueous sodium alginate solution, followed by stirring and ultrasonic treatment for 20 minutes to obtain Slurry A. The zeolite material was one or more of MFI molecular sieves, MEL molecular sieves, and FER molecular sieves, each with a silicon-aluminum ratio greater than 100 and a particle size less than 10 μm.

[0057] Slurry A is sucked up and dropped onto a melamine foam material, and aged at room temperature for 60 minutes. The density of the melamine foam is 10 to 100 mg / cm. 3 and the porosity is greater than 60%.

[0058] The aged sample is then freeze-dried using a freeze-dryer.

[0059] After the freeze-drying process is complete, the obtained sample is placed in an 80°C environment and baked for 2 hours to dehydrate it, thereby obtaining the desired sound-absorbing material block. Comparative Example 2

[0060] In this comparative example, the sound-absorbing material block is manufactured by the following steps.

[0061] 0.08 g of polyacrylamide was weighed and added to 8 g of water at room temperature and stirred for 20 minutes to form a uniform and transparent aqueous polyacrylamide solution. 4 g of zeolite material and 0.8 g of polystyrene acetate (solid content 50 wt%) were then added to the aqueous polyacrylamide solution, followed by stirring and ultrasonic treatment for 20 minutes to obtain Slurry A. The zeolite material was one or more of MFI molecular sieves, MEL molecular sieves, and FER molecular sieves, each with a silicon-to-aluminum ratio greater than 100 and a particle size less than 10 μm.

[0062] Slurry A is sucked up and dropped onto a melamine foam material, and aged at room temperature for 60 minutes. Here, the density of the melamine foam is 10 to 100 mg / cm. 3 and the porosity is greater than 60%.

[0063] The aged sample is then freeze-dried using a freeze-dryer.

[0064] After the freeze-drying process is complete, the obtained sample is placed in an 80°C environment and baked for 2 hours to dehydrate it, thereby obtaining the desired sound-absorbing material block. Comparative Example 3

[0065] In this comparative example, the sound-absorbing material block is manufactured in the following steps.

[0066] 0.05 g of sodium alginate was weighed and added to 8 g of water at room temperature and stirred for 20 minutes to form a uniform and transparent aqueous sodium alginate solution. 4 g of zeolite material and 0.2 g of styrene-butadiene latex (solid content 50 wt%) were then added to the aqueous sodium alginate solution, followed by stirring and ultrasonic treatment for 20 minutes to obtain Slurry A. The zeolite material was one or more of MFI molecular sieves, MEL molecular sieves, and FER molecular sieves, each with a silicon-to-aluminum ratio greater than 100 and a particle size less than 10 μm.

[0067] 0.005 g of calcium chloride was added to Slurry A, and the mixture was stirred at room temperature for 10 minutes to obtain Slurry B.

[0068] Slurry B is sucked up and dropped into a Teflon mold, and aged at room temperature for 60 minutes.

[0069] The aged sample is then freeze-dried using a freeze-dryer.

[0070] After the freeze-drying process is complete, the obtained sample is placed in an 80°C environment and baked for 2 hours to dehydrate it, thereby obtaining the desired sound-absorbing material block. Acoustic Performance Test

[0071] Using normal sound-absorbing particles as a control, acoustic performance tests are carried out on the sound-absorbing material blocks of Examples 1 to 3 and Comparative Examples 1 to 3.

[0072] Based on the method for measuring the resonant frequency of a speaker, the sound-absorbing material blocks of Examples 1 to 3 and Comparative Examples 1 to 3 were placed in a test device, and an impedance analyzer was used to measure the reduction in their resonant frequency (F0) (i.e., ΔF0). Here, the reduction in F0 indicates the degree to which the resonant frequency shifts to lower frequencies, and generally, the larger the ΔF0, the better the low-frequency performance of the speaker.

[0073] In the experiment, each sample was 10mm*12mm*2mm / 0.24cm 3The volume of the normal sound-absorbing particles used is also 0.24cc, and the volume of the rear cavity of the speaker in the test equipment is also 0.4cc.

[0074] Furthermore, the sound absorbing material blocks of Examples 1 to 3 and Comparative Examples 1 to 3 were measured for damage caused by dropping using a drop test.

[0075] The test results are shown in the table below. JPEG0007771102000001.jpg71170

[0076] The data in the table above shows that the sound-absorbing performance of the sound-absorbing material blocks in Examples 1 to 3 of the present invention is superior to that of ordinary sound-absorbing particles, and they do not fall off. The difference in performance between Examples 1 to 3 is due to the difference in the gelling agent added and the difference in the amount of zeolite added.

[0077] The sample in Comparative Example 1 had better sound absorption performance than Example 1, but because no crosslinking agent was added and the sound-absorbing powder did not form a gel crosslinked structure, the sample suffered from severe powder shedding. In Comparative Example 2, the adhesive content was increased but no crosslinking agent was added. The sample in Comparative Example 2 passed the drop test without powder shedding, but its sound absorption performance was significantly reduced. In Comparative Example 3, Slurry B was dried directly in the mold, and the sample had high sound absorption performance, but because there was no support from the foam holder, the sample broke and powdered after being dropped.

[0078] Although the objectives, technical solutions and advantages of the present invention have been described in detail above, it should be understood that the above descriptions are merely embodiments and specific examples of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. The foam includes a three-dimensional open-pore foam, a sound-absorbing powder, an adhesive, a gelling agent, and a cross-linking agent. The gelling agent bonds the sound-absorbing material powder to each other and connects them to the three-dimensional open-pore foam using a crosslinking agent and an adhesive, and depending on the mass of the sound-absorbing material powder, the gelling agent accounts for 1.25 to 2.22 wt % of the sound-absorbing material powder, the adhesive accounts for 3 to 6.67 wt % of the sound-absorbing material powder, and depending on the mass of the gelling agent, the crosslinking agent accounts for 6.25 to 10 wt % of the gelling agent. A sound-absorbing block characterized by:

2. the crosslinking agent is one or more of N,N'-methylenebisacrylamide, boric acid, calcium chloride, and aluminum chloride; 2. The sound-absorbing material block according to claim 1.

3. The three-dimensional open-pore foam has a porosity of more than 60% and a density of 10 to 100 mg / cm ３ That is, 2. The sound-absorbing material block according to claim 1.

4. The three-dimensional open-pore foam is a melamine foam or a polyurethane foam.

4. The sound-absorbing material block according to claim 1.

5. The sound-absorbing powder is a zeolite material consisting of one or more of MFI molecular sieves, MEL molecular sieves, and FER molecular sieves, each having a silicon-aluminum ratio of more than 100 and a particle size of less than 10 μm; 4. The sound-absorbing material block according to claim 1.

6. The adhesive is one or more of polyacrylic acid ester, styrene butadiene latex, polystyrene methyl acrylate, polystyrene acetate ester, polyurethane resin, and polyethyl vinyl acetate salt; 4. The sound-absorbing material block according to claim 1.

7. the gelling agent is one or more of sodium hydroxymethylcellulose, sodium alginate, chitosan, sodium polyacrylate, polyacrylamide, gelatin, polyvinyl alcohol; 4. The sound-absorbing material block according to claim 1.

8. 10. A method for manufacturing a sound-absorbing material block, the sound-absorbing material block being the sound-absorbing material block according to claim 1, the method comprising the steps of: Step S1: Co-mixing sound-absorbing powder, gelling agent, adhesive and solvent to form slurry A; Step S2: adding a crosslinking agent to the slurry A and stirring the mixture uniformly to obtain a slurry B; Step S3: adding the slurry B to the three-dimensional open-pore foam and aging the three-dimensional open-pore foam to form a gel; Step S4: drying the aged sample; and step S5 of dehydrating the dried sample to obtain the sound-absorbing material block. A method for manufacturing a sound-absorbing material block.

9. the solvent is one or more of water, methanol, ethanol, butanol, and ethyl acetate; 9. The method for manufacturing a sound-absorbing material block according to claim 8.

10. A speaker including a housing having an accommodation space, a sound generating unit disposed in the housing, and a rear cavity surrounded by the sound generating unit and the housing, The rear cavity is filled with the sound-absorbing material block according to claim 1. A speaker characterized by:

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