Sound-absorbing block material, preparation method therefor and use thereof

Abstract

The present invention provides a sound-absorbing block material, a preparation method therefor and a use thereof. The sound-absorbing block material has gradient pores having diameters that gradually increase from the inside to a surface layer. The thickness of the sound-absorbing block material is 0.5-5 mm. The sound-absorbing block material of the present invention has gradient pores, and the pore diameters gradually increase from the inside to the surface layer of the block material. The pores can cause the sound-absorbing material inside the sound-absorbing block material to be exposed to the air to function, and the gradient changes between the pores can reduce air vibration damping. The raw materials of the sound-absorbing material have high bonding strength therebetween, which reduces powder dropping and ensures the stability of the pore structure. The surface layer of the sound-absorbing block material has large pores having diameters of 20-200 μm. When the sound-absorbing block material is attached to a sound-emitting rear cavity, the attachment surface can also be exposed to the air to function, thereby improving the performance of the block material when used in rear cavities of loudspeakers with different morphologies.

Description

A sound-absorbing block material and its preparation method and application

Technical field

[0001] The present invention relates to the technical field of sound-absorbing materials, and in particular to a sound-absorbing block material, a preparation method thereof, and applications thereof. [Background Technology]

[0002] In the field of acoustics, filling the back cavity of a speaker with sound-absorbing material is commonly used to improve its acoustic quality, virtually increasing its volume. Given the small back cavity of small speakers found in mobile terminals and other electronic devices, filling with sound-absorbing material is an effective strategy, significantly improving low-frequency performance and significantly enhancing acoustic quality.

[0003] At present, most sound-absorbing powders are inorganic particles below 10μm, which cannot be directly added to the back cavity of the speaker. Otherwise, leakage of the powder will cause damage to the speaker. Therefore, the sound-absorbing powder is often formed into sound-absorbing particles or sound-absorbing blocks of a certain size. When the sound-absorbing particles are working in the back cavity of the high-frequency speaker, due to the vibration of the air in the back cavity, the particles collide, and the sound-absorbing particles will produce powder loss, reduced sound absorption performance and other problems. In severe cases, it may even damage the speaker. Sound-absorbing blocks avoid these problems, but due to their large size, sound-absorbing blocks hinder the air flow in the back cavity. The block has high damping, and some of the sound-absorbing powder on the block cannot play a role, resulting in poor sound absorption performance. Although people in this field have prepared ultra-thin sound-absorbing sheets, their application is limited and the strength of the sheet is low.

[0004] Therefore, in order to solve the problems existing in the above-mentioned sound-absorbing blocks, it is necessary to provide a new type of sound-absorbing block and its preparation method and application.

[0005] [Summary of the invention]

[0006] The object of the present invention is to provide a sound-absorbing block material, a preparation method thereof and an application thereof; the sound-absorbing block material has the characteristics of low damping, not easy to fall off powder and high strength.

[0007] The technical solutions of the present invention are as follows:

[0008] In a first aspect, the present invention provides a sound-absorbing block material having gradient pores with diameters gradually increasing from the interior to the surface; the pore diameter inside the sound-absorbing block material is 1-20 μm; the pore diameter on the surface of the sound-absorbing block material is 20-200 μm; and the thickness of the sound-absorbing block material is 0.5-5 mm.

[0009] Preferably, the gradient pores are arranged in one or more of longitudinal, transverse or staggered arrangements.

[0010] Preferably, the sound-absorbing block material comprises the following raw materials, in parts by weight: 100 parts of sound-absorbing powder, 3-15 parts of a binder, 1-10 parts of a thickener, and 80-200 parts of water.

[0011] Preferably, the sound-absorbing powder is a zeolite material with a particle size of less than 10 μm; the zeolite material includes one or more of MFI molecular sieve, MEL molecular sieve or FER molecular sieve.

[0012] Preferably, the binder comprises one or more of polyacrylate, styrene-butadiene emulsion, polystyrene acrylate, polystyrene acetate, polyurethane resin or polyethyl vinyl acetate salt.

[0013] Preferably, the thickener comprises one or more of sodium carboxypropyl methylcellulose, sodium polyacrylate, polyacrylamide, sodium alginate or gelatin.

[0014] Preferably, the sound-absorbing block is an integral structure or includes a plurality of block-shaped structural units.

[0015] In a second aspect, the present invention provides a method for preparing the above-mentioned sound-absorbing block material, comprising the steps of:

[0016] Blending raw materials to form a mixed slurry; wherein the raw materials include sound-absorbing powder, adhesive, thickener and water;

[0017] The obtained mixed slurry is filled into a pre-cooled mold, and the mold is placed in a low-temperature environment to freeze and crystallize the mixed slurry to obtain a frozen crystallized slurry; the mold pre-cooling temperature is 0 to -20°C, and the low-temperature environment temperature is 0 to -60°C;

[0018] The obtained frozen crystal slurry is subjected to vacuum freeze-drying treatment to obtain a sound-absorbing block material.

[0019] In a third aspect, the present invention provides an application of the sound-absorbing block material as described above in a loudspeaker, wherein the loudspeaker comprises the sound-absorbing block material and a sound-emitting rear cavity, wherein the sound-absorbing block material is filled in the sound-emitting rear cavity; the sound-absorbing block material matches part or all of the cavity of the sound-emitting rear cavity.

[0020] The beneficial effects of the present invention are:

[0021] The present invention provides a sound-absorbing block material, a preparation method thereof, and an application thereof. The sound-absorbing block material has gradient pores, and the pore diameter gradually increases from the interior to the surface of the block material. The pores can expose the sound-absorbing material inside the sound-absorbing block material to the air to exert its effect, and the gradient change between the pores can reduce the air vibration damping; the bonding strength between the raw materials of the sound-absorbing material is high, which reduces powder loss and ensures the stability of the pore structure; the surface layer of the sound-absorbing block material has large pores with a diameter of 20-200μm. When the sound-absorbing block material is bonded to the sound-generating back cavity, the bonding surface can also be exposed to the air to exert its effect, thereby improving the performance of the block material in the back cavity of speakers with different morphologies.

Brief Description of the Drawings

[0022] FIG1 is a SEM morphology test diagram of a cross section of the sound-absorbing block material of the present invention;

[0023] FIG2 is a microscope morphology test diagram of the surface of the sound-absorbing block material of the present invention. [Specific implementation method]

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative work shall fall within the scope of protection of the present invention.

[0025] An embodiment of the present invention provides a sound-absorbing block, as shown in Figures 1 and 2. The sound-absorbing block has gradient pores whose diameter gradually increases from the inside to the surface, and the gradient pores are filled with sound-absorbing material; the thickness of the sound-absorbing block is 0.5-5 mm.

[0026] The sound-absorbing block material of the present invention has gradient pores, and the diameter of the pores gradually increases from the inside to the surface of the block material. The pores can expose the sound-absorbing material inside the sound-absorbing block material to the air to play a role, and the gradient change between the pores can reduce the air vibration damping; the bonding strength between the raw materials of the sound-absorbing block material is large, which reduces powder loss and ensures the stability of the pore structure; the surface of the sound-absorbing block material is a large pore with a diameter of 20-200μm. When the sound-absorbing block material is bonded to the sound-generating back cavity, the bonding surface can also be exposed to the air to play a role, avoiding the performance degradation of conventional sound-absorbing blocks when used in the back cavity, and improving the performance of the blocks in the back cavities of speakers with different morphologies.

[0027] It should be noted that the surface layer in the present invention refers to the part of the sound-absorbing block that crystallizes first; it is also the part where the raw material contacts the mold during preparation; it also refers to the surface of the sample that contacts the sound cavity after the final preparation.

[0028] Preferably, the pore diameter within the sound-absorbing block is 1-20 μm, while the pore diameter on the surface of the sound-absorbing block is 20-200 μm. Specifically, starting from the geometric center of the sound-absorbing block, the pores in the center area are small and honeycomb-shaped, while the pores on the surface area are larger and more regular.

[0029] Preferably, as shown in FIG1 , the gradient pores are arranged in one or more of the following arrangements: longitudinal, transverse, or staggered. That is, the gradient pores are distributed in the sound-absorbing block in one of the following arrangements: longitudinal, transverse, or staggered; or in a mixture of two or three of the three. The pores may be distributed in staggered or parallel patterns, meaning that the gradient pores are distributed with equal spacing and / or unequal spacing.

[0030] Preferably, the sound-absorbing block comprises, by weight, 100 parts of sound-absorbing powder, 3-15 parts of a binder, 1-10 parts of a thickener, and 80-200 parts of water. The inclusion of a thickener significantly increases the block's strength and reduces powder loss. The high-strength block ensures a stable pore structure.

[0031] Preferably, the sound-absorbing powder is a zeolite material with a particle size of less than 10 μm; the zeolite material includes one or more of MFI molecular sieve, MEL molecular sieve or FER molecular sieve.

[0032] The binder includes one or more of polyacrylate, styrene-butadiene emulsion, polystyrene acrylate, polystyrene acetate, polyurethane resin or polyethyl vinyl acetate salt.

[0033] The thickener includes one or more of sodium carboxypropyl methylcellulose, sodium polyacrylate, polyacrylamide, sodium alginate or gelatin.

[0034] The sound-absorbing block material is an integral structure or includes a plurality of block-shaped structural units.

[0035] Furthermore, when the sound-absorbing block comprises a plurality of block-shaped structural units, the preparation scheme includes the following:

[0036] Option 1: Prepare thinner blocks and stack them in multiple layers to better increase the contact area between the blocks and the air.

[0037] Option 2: In the rear cavity of the speaker, the overall structure is divided into separate small blocks according to the actual situation of the cavity, and then foam cushioning or other breathable structures are added to them for use in combination.

[0038] In a second aspect, an embodiment of the present invention provides a method for preparing the above-mentioned sound-absorbing block material, comprising the steps of:

[0039] Blending raw materials to form a mixed slurry; wherein the raw materials include sound-absorbing powder, adhesive, thickener and water;

[0040] The obtained mixed slurry is filled into a pre-cooled mold, and the mold is placed in a low-temperature environment to freeze and crystallize the obtained mixed slurry to obtain a frozen crystallized slurry; the mold pre-cooling temperature is 0 to -20°C, and the low-temperature environment temperature is 0 to -60°C;

[0041] The obtained frozen crystal slurry is subjected to vacuum freeze-drying treatment to obtain a sound-absorbing block material.

[0042] The pores of the sound-absorbing block material described in the present invention are formed because water crystallization displaces other solid raw materials during the preparation process, and a pore structure is formed after the water sublimates and dries. The growth rate of ice crystals from the outside to the inside is controlled by optimizing the slurry viscosity and low-temperature freezing conditions. During the freezing crystallization process, there is a temperature gradient between the inside and the surface. The deeper into the block material, the weaker the force of the ice crystal displacing and the smaller the diameter of the pores, thereby finally forming a pore structure with a gradient change. The gradient change of the freezing temperature also affects the slurry. The lower the freezing temperature, the smaller the solid phase particle size, the lower the viscosity of the slurry, and the larger the pores formed. At the same time, during the preparation process, ice crystals and other solid phase components wrap around each other to form a swallowing phenomenon, so that a porous structure is formed in the obtained sound-absorbing block material.

[0043] In a third aspect, the present invention provides an application of the above-mentioned sound-absorbing block material in a loudspeaker, wherein the loudspeaker comprises the above-mentioned sound-absorbing block material and a sound-generating rear cavity, wherein the sound-absorbing block material is filled in the sound-generating rear cavity; the sound-absorbing block material matches a portion or all of the sound-generating rear cavity, that is, during the preparation of the sound-absorbing block material, by molding in different molds, a sound-absorbing block material that completely or partially fills the sound-generating rear cavity can be prepared. Specifically, the block material is prepared by molding the slurry in different molds. If the mold is prepared using the cavity as a template, the prepared block material completely fits the cavity. This is applicable to irregular, concave and convex cavity surfaces. If the cavity is not completely filled, the cavity contacts part of the wall surface.

[0044] Example 1

[0045] The preparation of the sound-absorbing block comprises the following steps:

[0046] 1. Mix 100 parts of zeolite, 10 parts of polystyrene acrylate emulsion adhesive, 5 parts of sodium carboxypropyl methylcellulose, and 150 parts of water and stir for 1 hour;

[0047] 2. Pre-cool the mold at -10°C for 1 hour, then take it out and add the mixed slurry into the mold. Then, place the mold containing the slurry in a -40°C environment for 30 minutes to obtain a frozen crystallized mixed slurry.

[0048] 3. The frozen crystallized slurry was placed in a freeze dryer and dried for 12 hours. The dried sample was placed in an oven at 100° C. and baked for 12 hours. After cooling to room temperature, the sound-absorbing block was obtained.

[0049] Comparative Example 1

[0050] The sound-absorbing block is prepared by a preparation method in the prior art, comprising the following steps:

[0051] 1. Mix 100 parts of zeolite, 10 parts of acrylic emulsion adhesive, 1 part of sodium carboxypropyl methylcellulose, and 150 parts of water and stir for 1 hour;

[0052] 2. Add the above mixed slurry into the mold, and then place the mold containing the slurry in a -10°C environment for 60 minutes to obtain a frozen crystallized mixed slurry;

[0053] 3. The frozen crystallized slurry was placed in a freeze dryer and dried for 12 hours. The dried sample was placed in an oven at 100° C. and baked for 12 hours. After cooling to room temperature, the sound-absorbing block was obtained.

[0054] In order to further illustrate the performance of the sound-absorbing block material and the advantages of the gradient pores, conventional sound-absorbing particles, Example 1 and Comparative Example 1 samples were tested and compared. For the purpose of unifying variables, the sound-absorbing blocks of different embodiments were prepared into 10*14*2mm 3 For a rectangular parallelepiped, conventional sound-absorbing particles of the same volume as the block were taken. The test included an impedance test and a drop test. The test cavity volume was 0.4 mL, and the drop method was repeated 10 times from a height of 1 m. The comparison results are shown in Table 1 below.

[0055] In the table above, the sound-absorbing block described in Example 1 achieved a 22Hz improvement in resonant frequency reduction (ΔF0) compared to conventional sound-absorbing particles of the same volume, and its peak impedance was 0.3Ω higher. The block material in Comparative Example 1 performed 13Hz lower than the sound-absorbing particles of the same volume, and its peak impedance was 1.2Ω lower. Analysis shows that because the sound-absorbing block described in Example 1 has a gradient porosity, its air permeability is improved, and the sound-absorbing powder is fully exposed to the air, fully exerting its sound-absorbing effect. Therefore, its impedance and sound-absorbing performance are superior to those of conventional sound-absorbing particles. Drop tests also show that the sound-absorbing block material is also strong and stable.

[0056] 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 block, characterized in that: The sound-absorbing block has gradient pores with diameters gradually increasing from the inside to the surface layer; the pore diameter inside the sound-absorbing block is 1-20 μm; the pore diameter on the surface layer of the sound-absorbing block is 20-200 μm; the thickness of the sound-absorbing block is 0.5-5 mm.

2. The sound-absorbing block according to claim 1, wherein: The gradient pores are arranged in one or more of longitudinal, transverse or staggered arrangements.

3. The sound-absorbing block according to claim 1, characterized in that: By weight, the sound-absorbing block comprises raw materials: 100 parts of the sound-absorbing powder, 3-15 parts of a binder, 1-10 parts of a thickener, and 80-200 parts of water.

4. The sound-absorbing block according to claim 3, characterized in that: The sound-absorbing powder is a zeolite material with a particle size less than 10 μm; the zeolite material comprises one or more of MFI zeolite, MEL zeolite or FER zeolite.

5. The sound-absorbing block according to claim 3, characterized in that: The binder comprises one or more of polyacrylate, styrene-butadiene latex, polystyrene acrylate, polystyrene acetate, polyurethane resin or polyethyl vinyl acetate salt.

6. The sound-absorbing block according to claim 3, characterized in that: The thickener comprises one or more of sodium carboxypropyl methylcellulose, sodium polyacrylate, polyacrylamide, sodium alginate or gelatin.

7. The sound-absorbing block according to claim 1, wherein: The sound-absorbing block is an integral structure or comprises a plurality of block structural units.

8. A method for preparing a sound-absorbing block according to any one of claims 1-7, characterized in that, Comprising the steps of: Blending the raw materials to form a mixed slurry; wherein the raw materials include a sound-absorbing powder, a binder, a thickener and water; Filling the obtained mixed slurry into a pre-cooled mold, and placing the mold in a low-temperature environment to freeze-crystallize the slurry to obtain a freeze-crystallized slurry; the pre-cooling temperature of the mold is 0 to -20 °C, and the temperature of the low-temperature environment is 0 to -60 °C; Performing vacuum freeze-drying treatment on the obtained freeze-crystallized slurry to obtain a sound-absorbing block.

9. Application of a sound-absorbing block as described in any one of claims 1-7 in a loudspeaker, characterized in that: The loudspeaker comprises the sound-absorbing block according to any one of claims 1-7 and a sounding rear cavity, and the sound-absorbing block is filled in the sounding rear cavity; the sound-absorbing block matches a part or all of the cavity of the sounding rear cavity.

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