Mute drum leather and preparation method thereof

Abstract

The invention belongs to the field of musical instruments, and particularly relates to mute drum leather and a preparation method thereof. The silent drum leather comprises an original sound drum leather layer, and a striking surface of the original sound drum leather layer is provided with a concave-convex structure; the microcellular foaming energy absorption layer and the bottom surface of the acoustic drum skin layer are compounded and are self-bonded into a whole; wherein the microcellular foaming energy absorption layer is of a closed-cell microcellular structure and is used for absorbing vibration energy; the concave-convex structure of the striking surface is used for dispersing sound head energy during striking, and the concave-convex structure and the microcellular foaming energy absorption layer are in synergistic effect to jointly achieve noise reduction and keep the striking touch feeling. According to the mute drum leather, the concave-convex structure is arranged on the striking surface of the original sound drum leather layer to disperse sound head energy, and the thermoplastic polyurethane material microcellular foaming layer is integrally formed on the back surface of the original sound drum leather layer through in-mold foaming to efficiently absorb vibration, so that the striking noise is remarkably reduced, and meanwhile, the real striking touch sense and rebound response are completely reserved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of musical instruments, and particularly relates to a mute drum skin and a preparation method thereof. BACKGROUND

[0002] The existing mute drum skin mainly relies on woven mesh structure or perforated film structure to reduce noise, but there are problems such as distorted touch, insufficient strength or insufficient volume suppression. For example, CN102930858A uses a multi-layer perforated film drum skin to reduce resonance; and the woven mesh drum skin cannot provide real striking feedback due to the difference in material elasticity. In addition, the traditional composite process needs to be bonded by an adhesive layer, which can affect vibration transmission and increase the risk of delamination. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a mute drum skin and a preparation method thereof. The mute drum skin disperses sound head energy by setting a concave-convex structure on the striking surface of the original sound drum skin layer, and integrally forms a microcellular foam layer by in-mold foaming on the back surface to efficiently absorb vibration, thereby significantly reducing striking noise while retaining the real striking touch and rebound response.

[0004] The present application provides a mute drum skin, comprising: an original sound drum skin layer, the striking surface of which is provided with a concave-convex structure; and a microcellular foam energy absorption layer, which is compounded and self-bonded with the bottom surface of the original sound drum skin layer as a whole; wherein the microcellular foam energy absorption layer has a closed-cell microcellular structure for absorbing vibration energy; the concave-convex structure on the striking surface is used to disperse sound head energy when striking, which cooperates with the microcellular foam energy absorption layer to achieve noise reduction and retain striking touch. Further, the microcellular foam energy absorption layer is integrally formed with the original sound drum skin layer by in-mold foaming process; the microcellular foam energy absorption layer is composed of thermoplastic polyurethane material impregnated and foamed by supercritical fluid under high pressure and pressure relief, and is self-bonded with the bottom surface of the original sound drum skin layer during the foaming process, forming a composite structure without additional adhesive layer.

[0005] Further, the supercritical fluid is supercritical carbon dioxide or nitrogen.

[0006] Further, in the in-mold foaming process, microwave-assisted heating or steam molding is used to promote the melting of the thermoplastic polyurethane material and the bonding with the original sound drum skin layer.

[0007] Further, a flame retardant is added to the microcellular foam energy absorption layer.

[0008] Further, the material of the original sound drum skin layer is polyester film, cowhide or sheepskin.

[0009] Further, the concave-convex structure of the striking surface is one of a hemispherical convex point, a pyramid convex point or a wave-shaped texture.

[0010] Further, the thickness of the raw drum skin layer is 0.1-0.4 mm. The convex height of the concave-convex structure of the striking surface is 0.1-0.5 mm, and the interval between the convexes is 1-3 mm.

[0011] Further, the thickness of the microcellular foaming energy-absorbing layer is 2-10 mm, the cell diameter of the closed-cell microcellular structure is 10-100 μm, and the density is 0.15-0.25 g / cm³.

[0012] The present application also provides a method for preparing the mute drum skin, comprising the following steps: Step S1: providing a raw drum skin layer and forming a concave-convex structure on the striking surface thereof; Step S2: placing a thermoplastic polyurethane material in a mold and positioning it opposite to the raw drum skin layer; Step S3: introducing a supercritical fluid into the mold and performing high-pressure impregnation of the thermoplastic polyurethane material under preset temperature and pressure conditions; Step S4: releasing the pressure of the mold to make the impregnated thermoplastic polyurethane material foam and form a microcellular foaming energy-absorbing layer in the mold, in the process, the molten thermoplastic polyurethane material is directly fused with the bottom surface of the raw drum skin layer to form a self-bonded integrated composite structure; Step S5: cooling and demolding to obtain the mute drum skin.

[0013] The present mute drum skin disperses the sound head energy by setting a concave-convex structure on the striking surface of the raw drum skin layer, and efficiently absorbs the vibration by integrally forming a microcellular foaming layer on the back surface through in-mold foaming, thereby significantly reducing the striking noise while completely retaining the real striking touch and rebound response. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a structural schematic diagram of the present application; Figure 2 is Figure 1 is a sectional view along A-A direction.

[0015] In the drawings, 1 is a raw drum skin layer; 11 is a concave-convex structure; 2 is a microcellular foaming energy-absorbing layer. DETAILED DESCRIPTION

[0016] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort are within the scope of the present application.

[0017] It should be noted that all the direction indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative position relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the direction indications also change accordingly.

[0018] In addition, the descriptions such as “first”, “second” and the like in the present application are only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as “first” and “second” can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of “plurality” is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0019] In the present application, unless otherwise specifically defined and limited, the terms “connection”, “fixation” and the like should be understood in a broad sense, for example, “fixation” can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection, or physical connection, or wireless communication connection; can be direct connection, or indirect connection through an intermediate medium; can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise specifically defined. For a person of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0020] In addition, the technical solutions of each embodiment of the present application can be combined with each other, but it must be based on the fact that a person of ordinary skill in the art can realize it, and when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the scope of protection claimed by the present application.

[0021] As shown in Figure 1 and Figure 2 The present application is a mute drum skin, which comprises: a raw drum skin layer 1, the striking surface of which is provided with a concave-convex structure 11; and a micro-porous foamed energy-absorbing layer 2, which is compounded with the bottom surface of the raw drum skin layer 1 and is integrally self-bonded; The microcellular foam energy absorption layer 2 has a closed-cell microcellular structure for absorbing vibration energy; the concave-convex structure 11 of the striking surface is used to disperse the energy of the sound head when striking, which cooperates with the microcellular foam energy absorption layer 2 to achieve noise reduction and retain the striking touch.

[0022] Specifically, the concave-convex structure 11 effectively weakens the intensity of the sound head by dispersing the concentrated striking energy into multiple dispersed micro-vibrations, and increases the action area of the vibration transmitted to the microcellular foam energy absorption layer 2; the microcellular foam energy absorption layer 2 contacts and efficiently absorbs the dispersed vibration energy through the closed-cell microcellular structure distributed therein, thereby achieving cooperative vibration suppression; the two together form an energy regulation system of surface dispersion and large-area back absorption, which significantly reduces the striking noise.

[0023] It should be noted that the striking noise mainly refers to: 1. The concentrated high-frequency impact sound waves radiated by the sharp vibration of the drum surface at the moment of striking. 2. The booming sound and long-lasting echo of the middle and low frequency bands produced by the continuous and overall vibration of the drum skin. 3. The vibration energy that causes unnecessary resonance of the drum cavity or other components.

[0024] In the present application, the concave-convex structure 11 disperses the concentrated sound head impact energy into multiple directions and different phase micro-vibrations. This directly destroys the cooperative vibration mode that produces strong and concentrated sound waves, fundamentally weakening the intensity of the sound head noise radiated. That is, it effectively reduces the first kind of noise, the high-frequency impact sound waves at the moment of striking.

[0025] For the second kind of noise, i.e. the middle and low frequency booming sound and long-lasting echo produced by the continuous vibration of the drum skin, it is mainly suppressed by the microcellular foam energy absorption layer 2. The foam layer absorbs and dissipates the middle and low frequency vibration energy efficiently by virtue of its internal closed-cell microcellular structure, and converts mechanical energy into heat energy through air friction and material internal friction, thereby greatly attenuating the vibration that causes resonance and echo.

[0026] For the third kind of noise, i.e. the wideband vibration energy that is easy to cause resonance of the drum cavity or other components, it is blocked by the cooperative action of the concave-convex structure 11 and the microcellular foam energy absorption layer 2. The concave-convex structure 11 first disperses such wideband vibration, increasing its contact area with the foam layer; then the microcellular foam energy absorption layer 2 contacts and efficiently absorbs the dispersed wideband micro-vibration energy, thereby cutting off the path of vibration transmission to the surrounding structure.

[0027] The microcellular foam energy absorption layer 2 mainly absorbs and dissipates the middle and low frequency vibration energy (which is the main cause of excessive resonance and echo), as well as the wideband micro-vibration energy dispersed by the concave-convex structure. The closed-cell microcellular structure converts these vibration energies into heat energy through air friction and material internal friction, greatly attenuating the vibration that causes noise.

[0028] In addition, while achieving targeted noise reduction, the present application retains necessary performance feedback through the following design: 1. The striking surface is directly formed by the original drum skin layer 1, which provides the same surface hardness and friction characteristics as traditional drum skin; the microcellular foam energy absorption layer 2 is compounded on the back, without changing the direct mechanical feedback of the striking surface, and maintaining the true drum skin touch 2. Through the combined action of the elasticity of the microcellular foam energy absorption layer 2 and the concave-convex structure 11, the striking energy is preferentially dispersed and absorbed, and the necessary high-frequency mechanical signals reflecting the striking force and rhythm are allowed to pass quickly and attenuate, thereby simulating the dynamic process of the true drum skin rapidly deforming and rebounding after being hit. The true drum skin rebound response and useful sound feedback are maintained.

[0029] The mute drum skin provided by the present application has the following effects: 1. Through the synergistic mechanism of surface concave-convex dispersion of high-frequency impact and back foam absorption of mid-low frequency resonance, the three main striking noises are targetedly suppressed, and the overall noise reduction effect is significant (more than 60%), rather than simply weakening all sounds indiscriminately.

[0030] 2. While efficiently absorbing noise energy, the necessary mechanical feedback signals are allowed to pass, so that the striking surface can still provide similar hardness, friction and dynamic rebound response to traditional drum skin, solving the core pain point of touch distortion in traditional mute solutions.

[0031] In one embodiment, the microcellular foam energy absorption layer 2 is integrally formed with the original drum skin layer 1 by in-mold foaming process; the microcellular foam energy absorption layer 2 is composed of thermoplastic polyurethane material impregnated by supercritical fluid under high pressure and foamed by pressure relief, and is self-bonded with the bottom surface of the original drum skin layer 1 during the foaming process, forming a composite structure without additional adhesive layer.

[0032] In this embodiment, firstly, the self-bonding forms a firm and complete interface, avoiding the interference of traditional adhesive layer on vibration transmission and the potential delamination risk, ensuring the long-term stability of noise reduction effect; secondly, the in-mold foaming and compounding are completed in one step, simplifying the production process and improving the consistency and production efficiency of the product; in addition, the supercritical fluid is used as a physical foaming agent, which is environmentally friendly and has no chemical residues, meeting the requirements of green manufacturing.

[0033] In other embodiments, the material of the microcellular foamed energy-absorbing layer 2 is not limited to the aforementioned thermoplastic polyurethane, and other thermoplastic elastomer materials with similar elasticity and damping properties can also be selected, such as at least one of thermoplastic polyolefin elastomer, ethylene-vinyl acetate copolymer, or polyolefin elastomer. These materials can also form a foamed layer with a closed-cell microcellular structure through existing production methods, and achieve melt self-bonding with the original drum skin layer 1.

[0034] In one of the embodiments, the supercritical fluid is supercritical carbon dioxide or nitrogen.

[0035] In this embodiment, first, supercritical carbon dioxide as a physical foaming agent can completely escape after the process is completed without any chemical residue, ensuring the environmental friendliness and safety of the final product; second, its excellent permeability and diffusion capacity help to form a more uniform and fine closed-cell microcellular structure in the thermoplastic polyurethane material, thereby improving the vibration energy absorption efficiency and mechanical consistency of the microcellular foamed energy-absorbing layer 2; third, the supercritical carbon dioxide technology is relatively mature and easy to achieve precise process control, which is conducive to the stable and large-scale production of the silent drum skin.

[0036] In one of the embodiments, in the in-mold foaming process, microwave-assisted heating or steam molding is used to promote the melting of the thermoplastic polyurethane material and bonding with the original drum skin layer 1.

[0037] In this embodiment, on the one hand, microwave-assisted heating or steam molding can achieve faster and more uniform heat transfer, not only shortening the process cycle and reducing energy consumption, but more importantly, ensuring the uniformity of the thermoplastic polyurethane material melting and the integrity of the interfacial bonding, thereby significantly improving the interfacial bonding strength and overall durability of the composite structure; on the other hand, a uniform and controllable heating environment helps to maintain the uniformity and stability of the cell structure during the foaming process of the thermoplastic polyurethane material, further ensuring the consistency and reliability of the vibration absorption performance of the microcellular foamed energy-absorbing layer 2, and ultimately facilitating the optimization of the performance of the silent drum skin product and stable mass production.

[0038] In one of the embodiments, a flame retardant is added to the microcellular foamed energy-absorbing layer 2.

[0039] In this embodiment, the comprehensive performance and application safety of the mute drumhead are significantly improved: first, the addition of the flame retardant makes the microcellular foam energy absorption layer 2 have good flame retardant properties, effectively reducing the risk of combustion of the material under high temperature or accidental fire, making the mute drumhead suitable for professional scenes such as stages and studios that have higher requirements for fire safety; second, the selected flame retardant (such as ammonium polyphosphate or nano calcium carbonate) has good compatibility with the thermoplastic polyurethane material matrix while achieving the flame retardant function, which ensures the integrity of the bubble structure inside the foaming layer and avoids negative effects on the core vibration absorption performance and elasticity; finally, this design gives the product a high-value safety attribute without adding additional process steps, which widens its market application range.

[0040] In one of the embodiments, the material of the original drumhead layer 1 is polyester film, cowhide or sheepskin.

[0041] In one of the embodiments, the concave-convex structure 11 of the striking surface is one of a semispherical convex point, a pyramid convex point or a wave-shaped texture.

[0042] In this embodiment, the semispherical convex point can achieve uniform and soft energy dispersion, which is conducive to obtaining a smooth touch and balanced noise reduction effect; the pyramid convex point can scatter vibration with more explicit geometric guidance, and the weakening effect on high-frequency impact sound waves is more significant, which is suitable for scenes that require extreme sound head suppression; the wave-shaped texture can provide continuous and directional energy guidance, and can form coherent vibration management on a larger area, which is conducive to maintaining the consistency of tone. The various texture patterns provide flexible design options for matching different playing styles, strength habits and tone preferences, and these structures can be efficiently realized through mature molding or carving processes, taking into account performance optimization and production feasibility.

[0043] In one of the embodiments, the thickness of the original drumhead layer 1 is 0.1-0.4 mm. The convex height of the concave-convex structure 11 of the striking surface is 0.1-0.5 mm, and the distance between the convexities is 1-3 mm.

[0044] In this embodiment, the thickness of the original drumhead layer 1 can maintain sufficient mechanical strength to withstand impact, and at the same time, it will not excessively suppress high-frequency vibration feedback due to its own excessive mass, ensuring the sensitivity and authenticity of the touch. At the same time, the matching design of the convex height and the distance can accurately scatter the sound head energy without excessively changing the macroscopic flatness of the striking surface, and efficiently increase the vibration contact area with the back microcellular foam energy absorption layer 2, thereby optimizing the energy transmission path on a micro scale.

[0045] In addition, in this parameter range, the concave-convex structure 11 can maintain good structural integrity under long-term repeated impact, and is not prone to collapse or wear due to stress concentration, thereby ensuring the long-term stability of the noise reduction performance of the product.

[0046] In one embodiment, the microcellular foam energy-absorbing layer 2 has a thickness of 2-10 mm, a closed-cell microcellular structure with a cell diameter of 10-100 μm, and a density of 0.15-0.25 g / cm³.

[0047] In this embodiment, the thickness of 2-10 mm of the microcellular foam energy-absorbing layer 2 provides sufficient physical space and material volume for the absorption and dissipation of vibration energy, ensuring a significant noise reduction depth. The combination of the micron-level closed-cell structure of 10-100 μm and the density of 0.15-0.25 g / cm³ enables the foamed layer to have a large internal surface area and an optimized air-polymer ratio at the micro level, and efficiently converts low-frequency and dispersed wide-frequency vibration energy into heat energy through air friction and material viscoelastic internal friction.

[0048] The present application also provides a method for preparing the above-mentioned silent drum skin, comprising the following steps: Step S1: providing a raw drum skin layer 1 and forming a concave-convex structure 11 on the striking surface thereof; Step S2: placing a thermoplastic polyurethane material in a mold and positioning it opposite to the raw drum skin layer 1; Step S3: introducing a supercritical fluid into the mold and performing high-pressure impregnation of the thermoplastic polyurethane material under preset temperature and pressure conditions; Step S4: releasing the pressure of the mold to make the impregnated thermoplastic polyurethane material foam and form a microcellular foam energy-absorbing layer 2 in the mold, and in this process, the molten thermoplastic polyurethane material is directly fused with the bottom surface of the raw drum skin layer 1 to form a self-bonded integrated composite structure; Step S5: cooling and demolding to obtain the silent drum skin.

[0049] In this method, by steps S3 and S4, the molten state of the thermoplastic polyurethane material is directly fused with the bottom surface of the raw drum skin layer 1 during the pressure release and foaming process after supercritical fluid impregnation. This fundamentally eliminates the interface impedance, aging delamination risk and interference with vibration transmission caused by the traditional adhesive layer, ensuring that the final product has a complete structure, a firm interface and a direct vibration transmission path, which is the key to ensuring its excellent noise reduction performance and long service life.

[0050] The method completes the two key steps of foaming and lamination in one step within the mold (step S4). This greatly simplifies the production process, reduces downstream assembly or bonding processes, not only improves production efficiency and reduces manufacturing costs, but more importantly, ensures the thickness, density, pore size distribution, and uniformity of the microporous foamed energy-absorbing layer 2 in each product, as well as the uniformity of its lamination with the drum skin layer. This guarantees a high degree of consistency in product performance and is particularly suitable for large-scale production.

[0051] Using supercritical fluids (such as CO2) as physical foaming agents (step S3), the process is clean and environmentally friendly, leaving no chemical foaming agent residue, and the product is safe and harmless. Simultaneously, by precisely controlling the parameters of impregnation and depressurization (temperature, pressure, time), the microstructure (cell size, density) and macroscopic morphology (thickness) of the microporous foamed energy-absorbing layer can be precisely controlled, achieving designability of the final acoustic and mechanical properties of the product.

[0052] The method's step settings (first forming the concave-convex structure 11 and then laminating) and process parameter window directly serve and ensure the realization of the product's core energy regulation mechanism of "surface dispersion - backside absorption". The uniform foam layer and the solid interface ensure the stability and durability of the noise reduction effect, while the original sound drumhead layer 1 has undergone surface treatment before lamination, thus fully preserving its authentic tactile feel as a striking surface.

[0053] The above description is merely an embodiment and does not constitute any limitation on the present invention. Any person skilled in the art can make many possible variations, modifications, or alterations to the technical solutions of the present invention without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.

Claims

1. A mute drumhead, characterized by, The drum skin comprises: a raw drum skin layer (1) having a hitting surface provided with a concave-convex structure (11); and a microcellular foaming energy-absorbing layer (2) which is compounded with the bottom surface of the raw drum skin layer (1) and is integrally self-bonded. The microcellular foaming energy-absorbing layer (2) has a closed-cell microcellular structure for absorbing vibration energy; the concave-convex structure (11) of the hitting surface is used for dispersing the energy of the sound head when being hit, and cooperates with the microcellular foaming energy-absorbing layer (2) to achieve noise reduction and retain the hitting touch. The microcellular foaming energy-absorbing layer (2) is integrally formed with the raw drum skin layer (1) by an in-mold foaming process; the microcellular foaming energy-absorbing layer (2) is composed of a thermoplastic polyurethane material which is impregnated under high pressure by a supercritical fluid and foamed by pressure relief, and is self-bonded with the bottom surface of the raw drum skin layer (1) during the foaming forming process to form a compound structure without an additional adhesive layer.

2. The mute drum head of claim 1, wherein, The supercritical fluid is supercritical carbon dioxide or nitrogen.

3. The mute drum head of claim 2, wherein, In the in-mold foaming process, microwave-assisted heating or steam molding is used to promote the melting of the thermoplastic polyurethane material and the bonding with the raw drum skin layer (1).

4. The mute drum head of claim 2, wherein, The microcellular foaming energy-absorbing layer (2) is added with a flame retardant.

5. The mute drum head of any one of claims 1-4, wherein, The material of the raw drum skin layer (1) is polyester film, cowhide or sheepskin.

6. The mute drum head of any one of claims 1-4, wherein, The concave-convex structure (11) of the hitting surface is one of a hemispherical convex point, a pyramidal convex point or a wavy texture.

7. The mute drum head of any one of claims 1-4, wherein, The thickness of the raw drum skin layer (1) is 0.1-0.4 mm; 8. The silent drum head as claimed in any one of claims 1 to 4, wherein, The height of the convex points of the concave-convex structure (11) of the hitting surface is 0.1-0.5 mm, and the distance between the convex points is 1-3 mm. The thickness of the microcellular foaming energy-absorbing layer (2) is 2-10 mm, the cell diameter of the closed-cell microcellular structure is 10-100 μm, and the density is 0.15-0.25 g / cm³.

9. The silent drum head as claimed in any one of claims 1 to 4, wherein, The method comprises the following steps:

10. A method of making the mute drumhead of any one of claims 1-9, characterized by, Step S1: providing a raw drum skin layer (1) and forming a concave-convex structure (11) on the hitting surface thereof; Step S2: placing a thermoplastic polyurethane material in a mold and positioning it with the raw drum skin layer (1); Step S3: introducing a supercritical fluid into the mold and impregnating the thermoplastic polyurethane material under a preset temperature and pressure; Step S4: releasing the pressure of the mold to make the impregnated thermoplastic polyurethane material foam and form a microcellular foaming energy-absorbing layer (2) in the mold, during which the molten thermoplastic polyurethane material is directly fused with the bottom surface of the raw drum skin layer (1) to form a self-bonded integrated compound structure; Step S5: cooling and demolding to obtain the mute drum skin. ​

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