Sound-absorbing microsphere and preparation method therefor, and loudspeaker

Abstract

A sound-absorbing microsphere and a preparation method therefor, and a loudspeaker. A sound-absorbing microsphere (100) is composed of a molecular sieve and an adhesive. The sound-absorbing microsphere (100) comprises a spherical body (101), and one or more hollow structures (102) recessed from the surface of the spherical body (101); and the maximum depth or the maximum width of the hollow structure (102) is 2% to 50% of the diameter of the spherical body (101). By forming the one or more hollow structures (102) in communication with the outside in the sound-absorbing microsphere (100), the sound-absorbing microsphere has a larger effective surface area and can adsorb more gas molecules, thereby achieving a better sound absorption effect, and the sound-absorbing microsphere filled in a loudspeaker (10) can achieve a better frequency reduction effect and significantly improve the acoustic performance of the loudspeaker. Compared with the prior art, the sound-absorbing microsphere (100) has a large effective surface area, and achieves good frequency reduction effect and great acoustic performance.

Description

Sound-absorbing microspheres, preparation method and loudspeaker Technical Field

[0001] The present invention relates to the technical field of electroacoustic conversion, and in particular to a sound-absorbing microsphere, a preparation method and a loudspeaker. Background Art

[0002] With the continuous development of portable electronic devices such as smartphones and Bluetooth headsets, people's requirements for audio quality are getting higher and higher. In order to improve audio quality and enhance the sound effect of speakers, one of the common practices currently adopted is to install sound-absorbing materials in the back cavity of the speaker to increase the volume of the virtual back cavity, thereby improving audio quality.

[0003] After the speaker is packaged, the effect of the cavity size on the overall resonant frequency is manifested as the smaller the cavity, the higher the resonant frequency; as a multi-porous structure material, molecular sieve can continuously adsorb and desorb the air in the cavity when the cavity vibrates, thereby indirectly achieving the effect of increasing the cavity volume; limited by the overall size of portable devices such as mobile phones, in order to obtain better low-frequency effects of speakers, on the one hand, the resonant frequency of the product is required to be as low as possible, and on the other hand, the speaker cavity is expected to be as small as possible to save space, which requires the development of cavity filling materials with higher frequency reduction performance. Technical issues

[0004] In related art, the sound-absorbing material filling the rear cavity of a speaker is typically spherical microspheres. Frequency reduction is achieved by placing multiple spherical microspheres in the rear cavity according to specific requirements. However, given the fixed overall structure of the spherical microspheres, their effective surface area also determines the amount of gas they can absorb. Since the same volume of sound-absorbing material can absorb more air, the effective surface area of ​​these spherical microspheres is small, resulting in a poor overall frequency reduction effect.

[0005] Therefore, it is necessary to provide a new sound-absorbing microsphere to solve the above technical problems. Solution

[0006] The object of the present invention is to provide a sound-absorbing microsphere with a hollow structure, thereby having a larger effective surface area and a better frequency reduction effect.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a sound-absorbing microsphere, which is composed of a molecular sieve and an adhesive; the sound-absorbing microsphere includes a spherical body and one or more hollow structures formed by surface depressions of the spherical body; the maximum depth or maximum width of the hollow structure is 2% to 50% of the diameter of the spherical body.

[0008] Preferably, the hollow structure is spherical or hemispherical.

[0009] Preferably, the molecular sieve comprises one or more of the structural types of MFI, FER and MEL; the molecular sieve is composed of silicon oxide and a second metal element; the second metal element comprises one or more of aluminum, iron, zinc and zirconium.

[0010] Preferably, the molar ratio between the silicon oxide and the second metal element is greater than or equal to 100.

[0011] In a second aspect, an embodiment of the present invention provides a method for preparing sound-absorbing microspheres, which is used to prepare the above-mentioned sound-absorbing microspheres. The preparation method comprises the following steps:

[0012] Step S1: Deionized water is sprayed into a cryogenic liquid having a temperature below 0°C by forming small droplets through spraying, micro-flow control or electrostatic separation, and the droplets are rapidly solidified to form ice beads floating on the surface of the cryogenic liquid;

[0013] Step S2: mixing the molecular sieve, adhesive and water and stirring them evenly to obtain a molecular sieve slurry;

[0014] Step S3, forming droplets of the molecular sieve slurry by spraying, micro-control flow or electrostatic separation, and spraying the droplets into a cryogenic liquid with the ice beads floating on the surface, so that the molecular sieve slurry droplets collide with the ice beads and quickly solidify to form microspheres and sink to the bottom;

[0015] Step S4: taking out the microspheres that have settled to the bottom, placing them in a low-pressure vacuum environment, and removing the ice in the microspheres by sublimation to obtain the sound-absorbing microspheres.

[0016] Preferably, the density of the cryogenic liquid is greater than 0.92 kg / L.

[0017] Preferably, the diameter of the ice beads suspended on the surface of the cryogenic liquid is less than 50% of the diameter of the liquid droplets.

[0018] Preferably, at least 50% of the ice beads have a diameter of 20 μm to 100 μm.

[0019] Preferably, at least 50% of the droplets have a diameter of 200 μm to 500 μm.

[0020] Preferably, in step S2, the mass ratio of the molecular sieve, the adhesive and the water satisfies the molecular sieve: the adhesive: the water = 1: 0.02-0.1: 0.5-2.

[0021] In a third aspect, an embodiment of the present invention provides a loudspeaker comprising a shell having a receiving space, a sound-emitting unit arranged in the shell, and a rear cavity surrounded by the sound-emitting unit and the shell, wherein the rear cavity is filled with the above-mentioned sound-absorbing microspheres. Beneficial effects

[0022] Compared with the prior art, the sound-absorbing microspheres of the present invention are composed of a molecular sieve and an adhesive. The microspheres comprise a spherical body and one or more hollow structures formed by surface depressions of the spherical body. The maximum depth or width of the hollow structures is 2% to 50% of the diameter of the spherical body. By forming one or more hollow structures connected to the outside on the sound-absorbing microspheres, the microspheres have a larger effective surface area, can adsorb more gas molecules, and thus have a better sound absorption effect. When filled in a speaker, the microspheres can achieve a better frequency reduction effect and significantly improve its acoustic performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive work, among which:

[0024] FIG1 is a schematic diagram of the three-dimensional structure of a sound-absorbing microsphere provided in an embodiment of the present invention;

[0025] FIG2 is a flow chart of a method for preparing sound-absorbing microspheres according to an embodiment of the present invention;

[0026] FIG3 is a schematic structural diagram of a loudspeaker provided in an embodiment of the present invention.

[0027] In the figure, 100, sound-absorbing microsphere, 101, spherical body, 102, hollow structure, 10, loudspeaker, 1, shell, 2, sound-emitting unit, 3, back cavity. Modes for Carrying Out the Invention

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] Example 1

[0030] Referring to Figure 1 , an embodiment of the present invention provides a sound-absorbing microsphere 100 composed of a molecular sieve and an adhesive. The microsphere 100 comprises a spherical body 101 and one or more hollow structures 102 formed by depressions in the surface of the spherical body 101. The maximum depth or width of each hollow structure is 2% to 50% of the diameter of the spherical body. By creating one or more externally connected hollow structures 102 on the sound-absorbing microsphere 100, the microsphere has a larger effective surface area, capable of absorbing more gas molecules and achieving better sound absorption. When used in a speaker 10, the microsphere can achieve better frequency reduction and significantly improve its acoustic performance.

[0031] In this embodiment, the hollow structure 102 is spherical or hemispherical.

[0032] In this embodiment, the molecular sieve comprises one or more of the structural types MFI, FER, and MEL. In this embodiment, the molecular sieve is composed of silicon oxide and a second metal element. In this embodiment, the second metal element comprises one or more of aluminum, iron, zinc, and zirconium.

[0033] In this embodiment, the molar ratio of the silicon oxide to the second metal element is greater than or equal to 100.

[0034] Example 2

[0035] 1 and 2 , an embodiment of the present invention provides a method for preparing sound-absorbing microspheres, which is used to prepare the above-mentioned sound-absorbing microspheres 100. The method comprises the following steps:

[0036] Step S1: Deionized water is formed into small droplets by spraying, micro-control flow or electrostatic separation and sprayed into a cryogenic liquid with a temperature below 0°C. After rapid solidification, the droplets become ice beads floating on the surface of the cryogenic liquid.

[0037] Step S2: Mix the molecular sieve, adhesive and water and stir them evenly to obtain a molecular sieve slurry.

[0038] Step S3: The molecular sieve slurry is formed into droplets by spraying, micro-controlled flow, or electrostatic separation, and then sprayed into a low-temperature liquid with the ice beads floating on the surface, so that the molecular sieve slurry droplets quickly solidify into microspheres after impacting the ice beads and sink to the bottom. The liquid has a relatively low temperature, so that the water droplets and the molecular sieve slurry droplets can quickly solidify upon contact with the liquid.

[0039] Preferably, when the number of ice beads floating on the surface of the cryogenic liquid is small, step S3 is paused and step S1 is repeated before continuing to step S3.

[0040] Specifically, the preparation methods of the ice beads and molecular sieve slurry droplets include but are not limited to spraying, micro-flow control, electrostatic separation, etc.

[0041] Step S4: taking out the microspheres that have settled to the bottom, placing them in a low-pressure vacuum environment, and removing the ice in the microspheres by sublimation to obtain the sound-absorbing microspheres 100.

[0042] Specifically, the sound-absorbing microsphere 100 obtained through the above steps S1 to S4 is manufactured with one or more hollow structures 102 connected to the outside, so that the sound-absorbing microsphere 100 has a larger effective surface area, can adsorb more gas molecules, and thus has a better sound absorption effect. Filling the sound-absorbing microsphere 100 in the speaker 10 can have a better frequency reduction effect and significantly improve its acoustic performance.

[0043] In this embodiment, the density of the cryogenic liquid is greater than 0.92 kg / L. The cryogenic liquid has an appropriate density, which is greater than that of ice so that small ice beads can float on the surface of the cryogenic liquid, waiting to combine with the molecular sieve slurry droplets. At the same time, the density is less than that of the microspheres solidified after the molecular sieve slurry droplets collide with the ice beads, so that the molecular sieve slurry droplets quickly sink to the bottom of the liquid after solidification, avoiding affecting the subsequent formation of microspheres.

[0044] Of course, the density and temperature of the cryogenic liquid can also be selected to have a suitable density so as to prepare sound-absorbing microspheres 100 of different densities.

[0045] Optionally, the cryogenic liquid includes liquid oxygen and liquid argon, etc.; of course, the cryogenic liquid is not limited to liquid oxygen and liquid argon, but can also be other cryogenic liquids.

[0046] In this embodiment, the diameter of the ice beads suspended on the surface of the cryogenic liquid is less than 50% of the diameter of the liquid droplets.

[0047] In this embodiment, at least 50% of the ice beads have a diameter of 20 μm to 100 μm.

[0048] In this embodiment, at least 50% of the droplets have a diameter of 200 μm to 500 μm.

[0049] In this embodiment, in step S2, the mass ratio of the molecular sieve, the adhesive, and the water satisfies the molecular sieve: the adhesive: the water = 1: 0.02-0.1: 0.5-2.

[0050] In this embodiment, in order to better reflect the performance test of the sound-absorbing microspheres 100 prepared by the present invention, the following Example 3, Example 4, Comparative Example 1 and Comparative Example 2 are specially prepared to obtain measurement results.

[0051] Example 3

[0052] An embodiment of the present invention provides a method for preparing sound-absorbing microspheres, the method comprising the following steps:

[0053] (1) Pour a certain amount of liquid oxygen into an open insulated container, and spray deionized water into the insulated container until a layer of ice beads floats on the surface of the liquid oxygen;

[0054] (2) Weigh 50 g of molecular sieve and add it to 60 g of deionized water, then add 10 g of acrylic adhesive with a solid content of 50% and stir evenly to obtain a molecular sieve slurry;

[0055] (3) spraying the molecular sieve slurry into the insulated container until most of the ice droplets on the surface of the liquid oxygen combine with the slurry droplets and sink into the liquid oxygen, and then stopping the spray granulation;

[0056] (4) The obtained molecular sieve microspheres are placed in a low-pressure vacuum environment until all water in the microspheres is removed by sublimation. The microspheres are then placed in an oven and dried at 120° C. for 2 h to obtain sound-absorbing microspheres 100 having a hollow structure 102.

[0057] Example 4

[0058] An embodiment of the present invention provides a method for preparing sound-absorbing microspheres, the method comprising the following steps:

[0059] (1) Pour a certain amount of liquid argon into an open insulated container, and spray deionized water into the insulated container containing the liquid argon until a layer of ice beads floats on the surface of the liquid argon;

[0060] (2) Weigh 50 g of molecular sieve and add it to 30 g of deionized water, then add 10 g of acrylic adhesive with a solid content of 50% and stir evenly to obtain a molecular sieve slurry;

[0061] (3) spraying the molecular sieve slurry into the insulated container until most of the ice droplets on the surface of the liquid argon combine with the slurry droplets and sink into the liquid argon, and then stopping the spray granulation;

[0062] (4) The obtained molecular sieve microspheres are placed in a low-pressure vacuum environment until all water in the microspheres is removed by sublimation. The microspheres are then placed in an oven and dried at 120° C. for 2 h to obtain sound-absorbing microspheres 100 having a hollow structure 102.

[0063] Comparative Example 1

[0064] The sound-absorbing microspheres 100 prepared in this comparative example 1 are prepared by the following steps:

[0065] (1) Weigh 50 g of molecular sieve and add it to 60 g of deionized water, then add 10 g of acrylic adhesive with a solid content of 50% and stir evenly to obtain a molecular sieve slurry;

[0066] (2) spraying the molecular sieve slurry into a heat-insulating container filled with liquid oxygen;

[0067] (3) The obtained molecular sieve microspheres are placed in a low-pressure vacuum environment until all water in the microspheres is removed by sublimation. The microspheres are then placed in an oven and dried at 120° C. for 2 h to obtain sound-absorbing microspheres 100 having a hollow structure 102.

[0068] Comparative Example 2

[0069] In this comparative example 2, sound-absorbing microspheres 100 are prepared by the following preparation method:

[0070] (1) Weigh 50g of molecular sieve and add it to 60g of deionized water. Then add 10g of acrylic adhesive with a solid content of more than 50% and stir evenly to obtain molecular sieve slurry.

[0071] (2) The molecular sieve slurry was subjected to high-temperature spray drying and granulation, and the obtained microspheres were placed in an oven and dried at 120°C for 2 hours to obtain 100 sound-absorbing microspheres.

[0072] Acoustic measurements of Example 3 to Comparative Example 2

[0073] The resonant frequency of the loudspeaker 10 is determined by measuring the frequency-dependent resistance and its phase, as well as its corresponding zero crossing point. The speaker 10 of the sound unit 2 is connected to an impedance analyzer, and microspheres with a diameter of 300-350 μm are selected to fill the rear cavity 3 of the speaker 10. The offset value of F0, namely ΔF0, is calculated by comparing it with the empty cavity.

[0074] The acoustic measurement results of the embodiments and comparative examples are as follows:

[0075] Sample cavity F0 (Hz) After filling with sample F0 (Hz) ΔF0 (Hz) Example 3 982741241 Example 4 981732249 Comparative Example 1 981768213 Comparative Example 2 982785197

[0076] The acoustic test results show that compared with the samples prepared by the conventional method, the sound-absorbing microspheres 100 prepared by the present method have a higher ΔF0 value, that is, have stronger sound absorption performance.

[0077] Example 5

[0078] Referring to Figure 3 , an embodiment of the present invention provides a loudspeaker 10 comprising a housing 1 having a housing space, a sound-emitting unit 2 disposed within the housing 1, and a rear cavity 3 enclosed by the sound-emitting unit 2 and the housing 1. The rear cavity 3 is filled with the aforementioned sound-absorbing microspheres 100. Filling the rear cavity 3 with the sound-absorbing microspheres 100 increases the acoustic compliance of the air in the rear cavity 3, thereby improving the low-frequency performance of the loudspeaker 10.

[0079] Compared with the prior art, the sound-absorbing microspheres of the present invention are composed of a molecular sieve and an adhesive. The microspheres comprise a spherical body and one or more hollow structures formed by surface depressions of the spherical body. The maximum depth or width of the hollow structures is 2% to 50% of the diameter of the spherical body. By forming one or more hollow structures connected to the outside on the sound-absorbing microspheres, the microspheres have a larger effective surface area, can adsorb more gas molecules, and thus have a better sound absorption effect. When filled in a speaker, the microspheres can achieve a better frequency reduction effect and significantly improve its acoustic performance.

[0080] The above description is only an embodiment of the present invention. It should be pointed out that those skilled in the art can make improvements without departing from the creative concept of the present invention, but these improvements all fall within the scope of protection of the present invention.

Claims

1. A sound-absorbing microsphere, characterized in that: The sound-absorbing microspheres are composed of a molecular sieve and an adhesive; the sound-absorbing microspheres include a spherical body and one or more hollow structures formed by surface depressions of the spherical body; the maximum depth or maximum width of the hollow structure is 2% to 50% of the diameter of the spherical body.

2. The sound-absorbing microsphere according to claim 1, characterized in that: The hollow structure is spherical or hemispherical.

3. The sound-absorbing microsphere according to claim 1, characterized in that: The molecular sieve includes one or more of the structural types of MFI, FER and MEL; the molecular sieve is composed of silicon oxide and a second metal element; the second metal element includes one or more of aluminum, iron, zinc and zirconium.

4. The sound-absorbing microsphere according to claim 3, characterized in that: The molar ratio of the silicon oxide to the second metal element is greater than or equal to 100.

5. A method for preparing sound-absorbing microspheres, for preparing the sound-absorbing microspheres according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: Step S1: Deionized water is formed into small droplets by spraying, micro-control flow or electrostatic separation and sprayed into a cryogenic liquid with a temperature below 0°C. After rapid solidification, the droplets become ice beads floating on the surface of the cryogenic liquid. Step S2: mixing the molecular sieve, adhesive and water and stirring them evenly to obtain a molecular sieve slurry; Step S3, forming droplets of the molecular sieve slurry by spraying, micro-control flow or electrostatic separation, and spraying the droplets into a low-temperature liquid with the ice beads floating on the surface, so that the molecular sieve slurry droplets quickly solidify to form microspheres after impacting the ice beads and sink to the bottom; Step S4: taking out the microspheres that have settled to the bottom, placing them in a low-pressure vacuum environment, and removing the ice in the microspheres by sublimation to obtain the sound-absorbing microspheres.

6. The method for preparing sound-absorbing microspheres according to claim 5, characterized in that: The density of the cryogenic liquid is greater than 0.92 kg / L.

7. The method for preparing sound-absorbing microspheres according to claim 5, characterized in that: The diameter of the ice beads suspended on the surface of the cryogenic liquid is less than 50% of the diameter of the liquid droplets.

8. The method for preparing sound-absorbing microspheres according to claim 7, characterized in that: At least 50% of the ice beads have a diameter of 20 μm to 100 μm.

9. The method for preparing sound-absorbing microspheres according to claim 7, characterized in that: At least 50% of the droplets have a diameter of 200 μm to 500 μm.

10. The method for preparing sound-absorbing microspheres according to claim 5, characterized in that: In step S2, the mass ratio of the molecular sieve, the adhesive, and the water satisfies the molecular sieve: the adhesive: the water = 1: 0.02-0.1: 0.5-2.

11. A loudspeaker comprising a housing having a receiving space, a sound-emitting unit disposed in the housing, and a rear cavity enclosed by the sound-emitting unit and the housing, wherein: The back cavity is filled with the sound-absorbing microspheres according to any one of claims 1 to 4.

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