An organic acoustic coating material for the inner cavity of a Chinese flute and a preparation method thereof

Abstract

This invention discloses an organic acoustic coating material for the inner cavity of a Chinese flute and its preparation method. The organic acoustic coating material comprises a film-forming component and a composite alcohol solvent, wherein the composite alcohol solvent accounts for 65%-75% of the total mass of the coating material. Based on 100 parts by mass of the film-forming component, the film-forming component includes: 86-93 parts dewaxed shellac, 2-6 parts boswellia carterii, 0.5-1.5 parts dehydrated castor oil, 0.5-1.5 parts oxidized turpentine, and 3-6 parts carnauba wax. The composite alcohol solvent comprises anhydrous ethanol and isopropanol, wherein the mass ratio of anhydrous ethanol to isopropanol is 60:40-80:20. This organic acoustic coating material can form a continuous, uniform, and stable organic composite film layer with acoustic performance adjustment properties on the surface of the inner cavity of a Chinese flute with a membrane, thereby effectively improving the stability of the surface consistency of the inner cavity and effectively improving problems such as the sharpness of the flute's tone.

Description

Technical Field

[0001] This invention belongs to the field of manufacturing and material modification technology of traditional Chinese wind instruments, specifically relating to an organic acoustic coating material for the inner cavity of a Chinese flute and its preparation method. Background Technology

[0002] The Chinese flute is a typical aerophone, and its sound production is closely related to the geometric parameters of its internal cavity, the condition of its surface, and the playing technique. The flute body is typically made of natural bamboo or wood, which varies in pore structure, fiber orientation, surface density, and moisture content. Therefore, the surface condition of the internal cavity and the working condition of the near-wall area are often inconsistent, affecting the consistency and stability of the sound. For the Chinese flute with a membrane, the nonlinear vibration of the membrane alters the harmonic energy distribution of the sound, selectively amplifying some higher harmonic components. These higher harmonic components are sensitive to changes in the continuity, roughness, and equivalent boundary acoustic impedance of the internal cavity surface. Therefore, differences in the surface condition of the internal cavity further contribute to differences in the distribution of higher harmonic energy and the overall auditory experience.

[0003] The coating material currently used in flute cavities is primarily unrefined natural shellac. Its main applications include basic moisture protection and surface sealing. However, the content and composition of primary waxes and impurities in unrefined natural shellac are unstable, hindering the formation of a continuous, uniform, and stable membrane layer within the flute's slender cavity. When the membrane layer on the cavity surface is too hard and brittle, it is difficult to properly dissipate and regulate high-frequency sound energy in the near-wall area, easily leading to relatively prominent higher harmonic components, resulting in a sharp tone or even noise. Furthermore, insufficient leveling of the membrane layer on the cavity surface easily leads to localized micro-undulations, flow marks, and uneven membrane thickness, resulting in decreased surface consistency and causing a decline in tonal consistency or insufficient sound production stability.

[0004] On the other hand, during actual performance, the exhaled warm and humid airflow easily forms condensation on the inner wall of the flute. Under continuous soaking and scouring, the membrane layer is prone to peeling or damage, leading to unstable acoustic performance of the flute. Therefore, there is still room for improvement in the existing coating materials in terms of application consistency, membrane layer stability, and functional adjustment of the flute's acoustic performance. Summary of the Invention

[0005] This invention provides an organic acoustic coating material for the inner cavity of a Chinese flute and its preparation method. Through the synergistic effect of its components, the organic acoustic coating material can form a continuous, uniform, stable, and acoustically modulating organic composite film layer on the surface of the flute's inner cavity.

[0006] The present invention provides an organic acoustic coating material for the inner cavity of a Chinese flute, comprising a film-forming component and a composite alcohol solvent, wherein the composite alcohol solvent accounts for 65%-75% of the total mass of the coating material; Based on a total mass of 100 parts, the film-forming components include: 86-93 parts dewaxed shellac, 2-6 parts mastic, 0.5-1.5 parts dehydrated castor oil, 0.5-1.5 parts oxidized turpentine, and 3-6 parts carnauba wax. The composite alcohol solvent includes anhydrous ethanol and isopropanol, wherein the mass ratio of anhydrous ethanol to isopropanol is 60:40-80:20.

[0007] Furthermore, based on a total mass of 100 parts of film-forming components, the film-forming components include: 88-92 parts of dewaxed shellac, 2-6 parts of mastic balsam, 0.5-1.5 parts of dehydrated castor oil, 0.5-1.5 parts of oxidized turpentine oil, and 3-6 parts of carnauba wax.

[0008] Furthermore, based on a total mass of 100 parts of film-forming components, the film-forming components include: 88-90 parts of dewaxed shellac, 4-6 parts of mastic balsam, 0.5-1.5 parts of dehydrated castor oil, 0.5-1.5 parts of oxidized turpentine oil, and 3-6 parts of carnauba wax.

[0009] Furthermore, based on a total mass of 100 parts of film-forming components, the film-forming components include: 90-92 parts of dewaxed shellac, 2-4 parts of mastic balsam, 0.5-1.5 parts of dehydrated castor oil, 0.5-1.5 parts of oxidized turpentine oil, and 3-6 parts of carnauba wax.

[0010] Furthermore, oxidized turpentine is obtained by oxidizing turpentine through natural air oxidation.

[0011] Another aspect of the present invention provides a method for preparing the above-mentioned organic acoustic coating material, comprising: S1: Dissolve dewaxed shellac in anhydrous ethanol to obtain a shellac ethanol pre-solution; S2: Dissolve frankincense balsam, dehydrated castor oil and oxidized turpentine oil in shellac ethanol pre-solution to obtain the main solution; S3: Carnauba wax was dissolved in isopropanol under heating conditions to obtain a wax dispersion; S4: After the wax dispersion has cooled naturally to 15℃-35℃, slowly add the wax dispersion to the main liquid under stirring to obtain the organic coating material.

[0012] Furthermore, step S3 specifically involves: first processing carnauba wax into powder, flakes, or small granules, then adding isopropanol, and dissolving the carnauba wax in isopropanol at a temperature of 65℃-75℃.

[0013] Furthermore, step S4 also includes filtering the organic coating material using a 200-300 mesh nylon filter cloth.

[0014] Compared with the prior art, the present invention has the following features and beneficial effects: The organic acoustic coating material of this invention forms a film layer with basic sealing function; at the same time, the organic acoustic coating material can also form a continuous and uniform film layer in the slender inner cavity of the Chinese flute, which can effectively reduce the fluctuation of the inner cavity surface state and thus improve the consistency of the inner cavity surface state.

[0015] 2. The membrane formed by the organic acoustic coating material of the present invention has moderate viscoelasticity, which can adjust the distribution of high-frequency harmonic energy in the cavity and avoid some high-order harmonics from protruding due to the hardness or unevenness of the membrane. This can improve the sharpness and noise of the tone and make the listening experience softer and more harmonious.

[0016] 3. The organic acoustic coating material of this invention can improve the water repellency of the membrane surface, inhibit the spread and wetting of condensate on the inner cavity surface during performance, thereby reducing the interference of condensate on the uniformity of the inner cavity surface.

[0017] 4. The organic acoustic coating material of the present invention has excellent performance stability. Under long-term use, the film formed by the coating material of the present invention still exhibits excellent film continuity, low three-dimensional roughness and excellent water repellency in areas where condensation water is easily affected.

[0018] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0019] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same parts in the exemplary embodiments of the invention.

[0020] Figure 1 A spectrum diagram of a C-key bamboo flute coated with the coating material of Example 1; Figure 2 A spectrum diagram of a C-key bamboo flute coated with the coating material of Example 2; Figure 3 A spectrum diagram of a C-key bamboo flute coated with the coating material of Example 3; Figure 4 A spectrum diagram of a C-key bamboo flute with a comparative coating material applied. Figure 5 Photographs of the inner surfaces of bamboo sample 1, bamboo sample 2 and bamboo sample 3; Figure 6The results show the three-dimensional roughness test of bamboo sample 1. Figure 7 The results show the three-dimensional roughness test results for bamboo sample 2. Figure 8 The results show the three-dimensional roughness test results for bamboo sample 3. Figure 9 The apparent contact angle measurement results are for bamboo sample 4; Figure 10 The apparent contact angle measurement results are for bamboo sample 5. Figure 11 The apparent contact angle measurement results are for bamboo sample 6; Figure 12 The apparent contact angle measurement results are for bamboo sample 7; Figure 13 Photographs taken after the sample flute has been axially cut open for observation following long-term use. Figure 14 The results show the three-dimensional roughness test of sample flute 1; Figure 15 The results show the three-dimensional roughness test of sample 2. Figure 16 The apparent contact angle measurement results are for sample flute 1; Figure 17 The apparent contact angle measurement results are for sample flute 2. Detailed Implementation

[0021] The present invention and its technical effects will be specifically described below with reference to specific embodiments and examples. Those skilled in the art should understand that these specific embodiments and examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0022] The organic acoustic coating material for the inner cavity of Chinese flutes provided by this invention includes film-forming components and a composite alcohol solvent; based on a total mass of 100 parts of film-forming components, the film-forming components include: 86-93 parts of dewaxed shellac, 2-6 parts of mastic balsam, 0.5-1.5 parts of dehydrated castor oil, 0.5-1.5 parts of oxidized turpentine oil, and 3-6 parts of carnauba wax.

[0023] As a preferred option, the film-forming components may include: 90 parts dewaxed shellac, 4 parts mastic balsam, 1 part dehydrated castor oil, 1 part oxidized turpentine oil, and 4 parts carnauba wax.

[0024] In this invention, dewaxed shellac is the main film-forming resin used to form a continuous film layer, providing basic sealing and film structure. The purpose of dewaxing and purification is to remove unstable primary waxes and impurities from natural shellac, thereby improving the film-forming continuity, transparency, and batch stability of the shellac resin phase. Carnauba wax, as a hydrophobic component, is used to adjust the water repellency and hygrothermal stability of the film surface. Boswellia serrata is mainly used to moderately adjust the viscoelasticity of the film layer, thereby improving its flexibility and film-forming state. Dehydrated castor oil and oxidized turpentine oil are mainly used to improve the film spreading and interfacial adhesion, assisting in the formation of a uniform film layer.

[0025] The composite alcohol solvent is mainly used to dissolve the film-forming components. The composite alcohol solvent accounts for 65%-75% of the total mass of the coating material, which is sufficient to meet the coating application requirements.

[0026] Furthermore, the complex alcohol solvent may include anhydrous ethanol and isopropanol, wherein the mass ratio of anhydrous ethanol to isopropanol may be 60:40-80:20, preferably 65:35-75:25, and more preferably 70:30.

[0027] In the complex alcohol solvents, anhydrous ethanol is mainly used to dissolve dewaxed shellac and mastic, and to disperse or dissolve dehydrated castor oil and oxidized turpentine in the shellac ethanol system; isopropanol is mainly used to dissolve carnauba wax when heated, and to help regulate the evaporation rate and spreading state of the coating material.

[0028] The above-mentioned oxidized turpentine oil is obtained by oxidizing turpentine oil through natural air oxidation. All other raw materials can be purchased directly from the market.

[0029] The preparation method of the above-mentioned organic acoustic coating material may include the following steps: S1: Dissolve the dewaxed shellac in anhydrous ethanol to obtain a clear shellac ethanol pre-solution.

[0030] S2: Add frankincense, dehydrated castor oil and oxidized turpentine to the shellac ethanol pre-solution to dissolve frankincense, dehydrated castor oil and oxidized turpentine to obtain the main solution.

[0031] Among them, frankincense, dehydrated castor oil and oxidized turpentine are all easily soluble in anhydrous ethanol. After adding frankincense, dehydrated castor oil and oxidized turpentine to the shellac ethanol pre-solution, they can be dissolved by gently shaking the container.

[0032] If necessary, the main liquid can be allowed to stand, be filtered and / or aged to remove undissolved particles and impurities and improve the consistency of the system state.

[0033] S3: Carnauba wax was dissolved in isopropanol under heating conditions to obtain a wax dispersion; Specifically, carnauba wax is first processed into powder, flakes or small granules, and then isopropanol is added. Carnauba wax can be quickly dissolved in isopropanol at a temperature of 65℃-75℃.

[0034] Gentle heating can be achieved using methods such as constant temperature water bath or jacket heating. The heating container should not be completely sealed, and proper venting should be maintained to avoid abnormal volatilization and accumulation of isopropanol or an increase in pressure inside the container.

[0035] S4: After the wax dispersion has cooled naturally to 15℃-35℃, slowly add the wax dispersion to the main liquid under stirring. The wax phase is gradually dispersed in the main liquid by stirring. Filter through a 200-300 mesh nylon filter cloth to obtain the organic coating material of the present invention, and seal and store it.

[0036] The wax dispersion obtained in step S3 is a clear solution. After standing and cooling, flocculent precipitate appears at the bottom, while the upper part of the solution is clear. After stirring, it becomes turbid. The final organic coating material is slightly turbid. It needs to be shaken or stirred before use. Apply the coating by inserting a coating tool (such as a sponge coating tool) into the inner cavity of the flute and repeating the process.

[0037] Several examples and comparative examples are provided below. In the examples and comparative examples, the dewaxed shellac, mastic balsam, dehydrated castor oil, carnauba wax, anhydrous ethanol, isopropanol, and turpentine are all commercially available. Among them, the mastic balsam is Chios mastic balsam, which is derived from the natural resin of the Boswellia carterii tree.

[0038] Oxidized turpentine is obtained by oxidizing turpentine through natural air oxidation. Specifically, turpentine is placed in a wide-mouthed container and allowed to continuously contact with air at room temperature, in a well-ventilated environment, away from heat sources, to undergo an oxidation reaction. The container is then gently shaken periodically to ensure sufficient contact between the gas and liquid. During this process, the volume of turpentine gradually decreases, its viscosity increases, and its color changes from light yellow to reddish-brown until a uniform reddish-brown viscous liquid is obtained. After filtering out impurities, oxidized turpentine is obtained.

[0039] The components and amounts of the organic acoustic coating materials in Examples 1-3 and the comparative examples are listed in Table 1.

[0040] Table 1. Components and dosages of each component in Examples 1-3 and the comparative examples.

[0041] Examples 1-3 only adjusted the mass fractions of dewaxed shellac and mastic, while keeping the mass fractions of other components constant. The comparative example retained carnauba wax while removing mastic, dehydrated castor oil, and oxidized turpentine. These examples and comparative examples aim to demonstrate the influence of the mass ratios of mastic, dehydrated castor oil, oxidized turpentine, and dewaxed shellac and mastic on the acoustic boundary and film formation state of the membrane.

[0042] The preparation methods of the organic coating materials in Examples 1-3 are as follows: S1: Dissolve dewaxed shellac in anhydrous ethanol to obtain a shellac ethanol pre-solution.

[0043] S2: Add frankincense, dehydrated castor oil and oxidized turpentine to the shellac ethanol pre-solution to dissolve frankincense, dehydrated castor oil and oxidized turpentine to obtain the main solution.

[0044] S3: Take carnauba wax, process it into thin sheets, add isopropanol, and use a constant temperature water bath method to quickly dissolve carnauba wax in isopropanol at a temperature of 70°C.

[0045] S4: After the wax dispersion has cooled to room temperature, slowly add the wax dispersion to the main liquid under stirring. The wax phase is gradually dispersed in the main liquid by stirring. Filter through a 300-mesh nylon filter cloth to obtain the organic coating material, and seal and store it.

[0046] The preparation method of the organic coating material in the comparative example is as follows: S1: Dissolve dewaxed shellac in anhydrous ethanol to obtain a shellac ethanol pre-solution.

[0047] S2: Take carnauba wax, process it into thin sheets, add isopropanol, and use a constant temperature water bath method to quickly dissolve carnauba wax in isopropanol at a temperature of 70°C.

[0048] S3: After the wax dispersion has cooled to room temperature, slowly add the wax dispersion to the shellac ethanol pre-solution under stirring. The wax phase is gradually dispersed in the main solution by stirring. Filter through a 300-mesh nylon filter cloth to obtain the organic coating material, and seal and store it.

[0049] The performance of the organic coating materials in Examples 1-3 and the comparative examples was tested.

[0050] I. Spectrum Testing: To compare the effects of different coating materials on the harmonic distribution of Chinese bamboo flutes, the inner wall of a C-key bamboo flute was coated with the coating materials from Examples 1-3 and the comparative example, respectively, to obtain sample flutes. Specifically, the coating material was applied twice to the inner wall of the C-key bamboo flute using a nylon brush at room temperature, with a 24-hour interval between the two applications. The coating was then allowed to naturally evaporate and dry to form a film. The C-key bamboo flute was then used for playing and recording, and the collected audio was subjected to spectral analysis.

[0051] Recordings were conducted in a recording studio environment using an AKG C214 condenser microphone and an Audient iD44 audio interface. The same tester used the sample flute to record the fundamental tone, the octave above the fundamental tone, the tone of the tuning hole, and the octave above the tone of the tuning hole sequentially. The fundamental tone was G4, the octave above the fundamental tone was G5, the tone of the tuning hole was C5, and the octave above the tone of the tuning hole was C6. Under the conditions of twelve-tone equal temperament and standard pitch A4 = 440Hz, the theoretical frequencies of these pitches are approximately 392.00Hz, 784.00Hz, 523.25Hz, and 1046.50Hz, respectively. Actual test frequencies may vary slightly depending on the flute's intonation, playing style, and environmental conditions. The resulting audio was then imported into Adobe Audition 2025 for spectral analysis of the fundamental tone and its multiple harmonic frequencies.

[0052] Please see Figure 1-4 The figures show the spectrum of a C-key bamboo flute coated with the materials from Examples 1-3 and the comparative example, respectively. Figures 1 to 4 It is evident that the C-key bamboo flutes treated with different coating materials exhibit certain differences in harmonic band distribution, higher frequency energy extension, and overall spectral morphology. Compared to the comparative examples, the spectra corresponding to Examples 1-3 all show varying degrees of change in higher frequency response, indicating that the film layers obtained from different formulations have a certain influence on the harmonic distribution of the bamboo flute with the membrane. Specifically, the spectra corresponding to Example 1 show a certain convergence trend in the higher frequency band; in the spectra corresponding to Example 3, the extension of some higher frequency harmonic bands is further weakened; and the spectra corresponding to Example 2 shows a relatively balanced performance between harmonic band integrity and higher frequency response convergence. Therefore, Example 2 demonstrates better overall performance under the test conditions.

[0053] It should be noted that the spectral results of the bamboo flute are still affected by factors such as blowing pressure, recording distance, pickup angle, individual differences in the sample tube, and playing conditions. In this invention, the spectral diagrams primarily serve as visual evidence of the changes in harmonic distribution after different membrane layer treatments, and are not considered as rigorous acoustic metrological test results. The above results indicate that the organic coating material of this invention has a directional regulating effect on the harmonic distribution of Chinese flutes with membranes.

[0054] II. Roughness Test: To verify the effect of different coating material formulations on the surface condition of the bamboo flute's inner cavity, the three-dimensional roughness of each bamboo sample surface was analyzed. Please refer to [link / reference]. Figure 5From left to right, the bamboo samples are sample 1, sample 2, and sample 3. Sample 1 is natural bamboo with no coating on its inner surface. Sample 2 has a natural shellac coating on its inner surface. Sample 3 has the coating material from Example 2 on its inner surface. Three-dimensional roughness analysis of the inner surface of each bamboo sample was performed using the Zygo Nexview 3D topography scanning system.

[0055] The three-dimensional roughness test employed a non-contact white light interferometry method to scan the microscopic morphology of the bamboo sample surface. Sa, Sq, and Sz were selected as evaluation parameters for the three-dimensional surface roughness according to the ISO 25178 standard. Sa is the arithmetic mean height, characterizing the average level of surface height undulation within the measurement area; Sq is the root mean square height, which is more sensitive to large local peak-valley variations; and Sz is the maximum height, characterizing the maximum height difference between the highest peak and the deepest valley within the measurement area.

[0056] Due to the natural curvature and axial morphology differences on the inner surface of bamboo samples, to avoid interference from macroscopic bending, cross-sectional curvature, and overall shape deviations on the micro-roughness results, a second-order polynomial surface removal process was performed on the original three-dimensional morphology data during the test data processing. Appropriate filtering was then used to extract the micro-roughness components of the sample surface. Three regions were selected for each type of sample, and two test points were selected for each region. R1, R2, and R3 represent different test regions, and P1 and P2 represent different test points within the same region.

[0057] The three-dimensional roughness test results of bamboo sample 1, bamboo sample 2, and bamboo sample 3 are shown below. Figure 6-8 The data for Sa, Sq, and Sz of each bamboo sample are listed in Table 2. The values ​​of Sa, Sq, and Sz in Table 2 refer to the average values ​​of Sa, Sq, and Sz.

[0058] Table 2. Sa, Sq, and Sz data for each bamboo sample

[0059] from Figure 6-8 As shown in Table 2, the values ​​of Sa, Sq, and Sz of bamboo sample 3 are significantly lower than those of bamboo sample 1 and bamboo sample 2, indicating that the roughness of bamboo sample 3 is significantly reduced compared to bamboo sample 1 and bamboo sample 2. Therefore, this demonstrates that the coating material of the present invention can form a continuous, smooth, and uniformly surfaced organic composite film on the inner surface of the bamboo flute.

[0060] Clearly, the coating material of this invention does not merely serve a simple sealing function; it can form a more uniform organic composite film layer on the inner surface of natural bamboo, thereby reducing the impact of the bamboo's original texture, local porosity, film flow marks, and uneven accumulation on the inner surface condition. For Chinese flutes with a membrane, this stable inner surface condition helps reduce the interference of near-wall boundary condition differences on the propagation of higher harmonics, thus providing an inner boundary basis for the stability of the flute's acoustic performance.

[0061] III. Hydrophobicity Test: To evaluate the water-repellent properties of the membrane surface, bamboo samples were selected for water droplet contact angle observation. The bamboo samples included: bamboo sample 4, bamboo sample 5, bamboo sample 6, and bamboo sample 7. Bamboo sample 4 was natural bamboo with no coating on its inner surface; bamboo sample 5 had a natural shellac coating on its inner surface; bamboo sample 6 had the coating material from Example 2 applied to its inner surface; and the coating material applied to the inner surface of bamboo sample 7 included: 94 parts dewaxed shellac, 4 parts boswellia carterii resin, 1 part dehydrated castor oil, 1 part oxidized turpentine oil, 163.3 parts anhydrous ethanol, and 70.0 parts isopropanol.

[0062] The LBADSA contact angle measurement method, suitable for curved substrates, was used for analysis. This method, based on the Young-Laplace equation, establishes a mechanical equilibrium model of the droplet's entire profile, fits the droplet profile, and obtains the contact angles on the left and right sides of the droplet and their average values. Since the bamboo inner cavity sample is not an ideal plane but a curved substrate with certain cross-sectional curvature, fiber texture, and local irregular undulations, this test used the straight line connecting the three-phase contact points on the left and right sides of the droplet as the geometric baseline for contact angle calculation, to improve the comparability of measurement results between different samples.

[0063] In the test, water droplets of the same volume were placed on the surface of each sample, and side-view images of the droplet falling process were acquired under the same lighting, shooting distance, and observation angle. To reduce the influence of droplet morphology fluctuations at the initial contact moment and subsequent spreading and evaporation on the measurement results, the third frame image after the droplet falls and contacts the sample surface was selected as the contact angle analysis image. Subsequently, this frame image was processed by grayscale conversion, horizontal correction, local area magnification, and droplet contour recognition. Based on the LBADSA method, droplet contour fitting was completed to obtain the left contact angle, right contact angle, and average contact angle of both sides.

[0064] Figure 9 The apparent contact angle measurement results are for bamboo sample 4; Figure 10 The apparent contact angle measurement results are for bamboo sample 5. Figure 11 The apparent contact angle measurement results are for bamboo sample 6; Figure 12 The apparent contact angle measurement results are for bamboo sample 7. Figure 9-12In the table, Figure (a) represents the apparent contact angle on the left side, and Figure (b) represents the contact angle on the right side. In Table 3, the first detected value is the apparent contact angle on the left side, and the second detected value is the contact angle on the right side.

[0065] Table 3 Contact angle data for each bamboo sample

[0066] Depend on Figure 9-12 As shown in Table 3: (1) The bamboo sample 4 without coating has the lowest apparent contact angle and the worst water repellency. Compared to bamboo sample 4, bamboo sample 5 coated with natural shellac showed an improved apparent contact angle, indicating that the natural shellac coating can improve the water repellency of the bamboo surface to some extent. (3) Compared with bamboo sample 5, the apparent contact angle of bamboo sample 7 was slightly improved. However, the apparent contact angle of bamboo sample 6 after the addition of carnauba wax was significantly improved, indicating that the addition of carnauba wax can further enhance the inhibition of water droplet spreading on the film surface and significantly enhance the water repellency performance.

[0067] IV. The condition of the membrane layer after long-term use: Two Chinese flutes of the same key and in similar condition were selected as samples for long-term playing observation. One flute had its inner cavity coated with the coating material of Example 2; this flute was designated Sample Flute 1. The other flute had its inner cavity coated with a natural shellac coating; this flute was designated Sample Flute 2. The two sample flutes were given to two postgraduate students specializing in bamboo flute performance for daily practice and performances before their solo concerts.

[0068] The testers used the sample flutes for approximately three months, from the date they received them until the end of the concert performance. During this period, both testers maintained at least 2 hours of actual playing time per day, including daily practice, music rehearsals, and concert performances, to observe the changes in the film state of the two types of coatings under long-term humid and hot airflow, condensation, and continuous playing conditions.

[0069] After the concert, the two sample flutes were cut open along their axial direction, revealing... Figure 13 The left side shows sample flute 1, and the right side shows sample flute 2. From... Figure 13 It can be seen that the inner cavity membrane layer of sample flute 1 is uniform overall, and there is no obvious large-area peeling, flaking or damage below the finger hole and in the area where water droplets flow. In the inner cavity of sample flute 2, there is obvious color deepening, local mottled and water-like traces, indicating that the surface state of the area repeatedly affected by condensation water changes significantly.

[0070] Roughness and hydrophobicity tests were conducted on two test areas of the inner wall of sample flutes 1 and 2, respectively. The first test area was the lower inner wall region near the blowhole; the second test area was the lower inner wall region near the third finger hole. Both test areas are located where condensation water is likely to collect, migrate, and flow along the inner wall below the finger holes during actual playing due to gravity.

[0071] The three-dimensional roughness test results of the inner cavity walls of sample flute 1 and sample flute 2 are shown in the figure below. Figure 14-15 The Sa, Sq, and Sz data for samples 1 and 2 are listed in Table 4. The Sa, Sq, and Sz values ​​in Table 4 refer to the average values ​​of Sa, Sq, and Sz.

[0072] Table 4. Sa, Sq, and Sz data for sample flute 1 and sample flute 2

[0073] The hydrophobicity of the inner surfaces of sample flute 1 and sample flute 2 was tested using the aforementioned method. The test results are shown in [Figure number missing]. Figure 16-17 And Table 5. Figure 16-17 Figure (a) shows the apparent contact angle on the left side, and Figure (b) shows the contact angle on the right side. In Table 5, the first detected value is the apparent contact angle on the left side, and the second detected value is the contact angle on the right side.

[0074] Table 5 Contact angle data for sample flute 1 and sample flute 2

[0075] Depend on Figure 14-17 As shown in Tables 4-5, after long-term use, sample flute 1 still maintains low roughness and excellent water repellency, indicating that the coating material of this invention has better performance stability than natural shellac coating.

[0076] Under actual playing conditions of approximately three months and at least 2 hours per day, the coating material of this invention still exhibits excellent film continuity, low three-dimensional roughness, and excellent water repellency in areas prone to condensation; while the natural shellac coating shows obvious wetting marks and surface condition changes in the corresponding areas. Clearly, the coating material of this invention possesses excellent performance stability under long-term actual playing conditions.

[0077] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. An organic acoustic coating material for the inner cavity of a Chinese flute, characterized in that: It includes film-forming components and composite alcohol solvents, wherein the composite alcohol solvents account for 65%-75% of the total mass of the coating material; Based on a total mass of 100 parts, the film-forming components include: 86-93 parts dewaxed shellac, 2-6 parts mastic, 0.5-1.5 parts dehydrated castor oil, 0.5-1.5 parts oxidized turpentine, and 3-6 parts carnauba wax. The composite alcohol solvent includes anhydrous ethanol and isopropanol, wherein the mass ratio of anhydrous ethanol to isopropanol is 60:40-80:

20.

2. The organic acoustic coating material as described in claim 1, characterized in that: Based on a total mass of 100 parts of film-forming components, the film-forming components include: 88-92 parts of dewaxed shellac, 2-6 parts of mastic balsam, 0.5-1.5 parts of dehydrated castor oil, 0.5-1.5 parts of oxidized turpentine oil, and 3-6 parts of carnauba wax.

3. The organic acoustic coating material as described in claim 1, characterized in that: Based on a total mass of 100 parts of film-forming components, the film-forming components include: 88-90 parts of dewaxed shellac, 4-6 parts of mastic balsam, 0.5-1.5 parts of dehydrated castor oil, 0.5-1.5 parts of oxidized turpentine oil, and 3-6 parts of carnauba wax.

4. The organic acoustic coating material as described in claim 1, characterized in that: Based on a total mass of 100 parts of film-forming components, the film-forming components include: 90-92 parts of dewaxed shellac, 2-4 parts of mastic balsam, 0.5-1.5 parts of dehydrated castor oil, 0.5-1.5 parts of oxidized turpentine oil, and 3-6 parts of carnauba wax.

5. The organic acoustic coating material as described in claim 1, characterized in that: The oxidized turpentine oil is obtained by oxidizing turpentine oil through natural air oxidation.

6. The method for preparing the organic acoustic coating material according to any one of claims 1-5, characterized in that, include: S1: Dissolve dewaxed shellac in anhydrous ethanol to obtain a shellac ethanol pre-solution; S2: Dissolve frankincense balsam, dehydrated castor oil and oxidized turpentine oil in shellac ethanol pre-solution to obtain the main solution; S3: Carnauba wax was dissolved in isopropanol under heating conditions to obtain a wax dispersion; S4: After the wax dispersion has cooled naturally to 15℃-35℃, slowly add the wax dispersion to the main liquid under stirring to obtain the organic coating material.

7. The preparation method according to claim 6, characterized in that: Step S3 specifically involves: first processing carnauba wax into powder, flakes, or small granules, then adding isopropanol, and dissolving the carnauba wax in isopropanol at a temperature of 65℃-75℃.

8. The preparation method according to claim 6, characterized in that: Step S4 also includes filtering the organic coating material using a 200-300 mesh nylon filter cloth.

Images