Sound absorbing panel

Abstract

To provide a sound absorbing panel that is better than a conventional one.SOLUTION: The sound absorbing panel is composed of a material that includes polyester fibres and thermally fused fibers including thermoplastic resin bound to the polyester fibres, and has a density of 0.2 g / cm3 to 0.24 g / cm3 and a thickness of 20 mm to 30 mm.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a sound absorbing board. [Background technology]

[0002] Patent Document 1 discloses a glass fiber sound absorbing sheet made mainly of glass fiber and cellulose fiber. The glass fiber sound absorbing sheet is an example of a sound absorbing board. This glass fiber sound absorbing sheet can achieve an average sound absorption coefficient of 0.4 or more in the frequency range from 200 Hz to 2000 Hz. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2014-521995 Summary of the Invention [Problem to be solved by the invention]

[0004] The frequency band of human voices produced by adult males and females is said to be 500 Hz to 1000 Hz. The sound absorption coefficient of the glass fiber sound absorbing sheet described in Patent Document 1 is extremely low at 500 Hz compared to the sound absorption coefficient at 1000 Hz. In other words, there is room for improvement in conventional sound absorbing boards. [Means for solving the problem]

[0005] The sound-absorbing board is made of a material containing polyester fiber and a heat-melting fiber containing a thermoplastic resin bonded to the polyester fiber, and has a density of 0.2 g / cm 3 from 0.24 g / cm 3 and the thickness is 20 mm to 30 mm. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic diagram showing a configuration of a board manufacturing apparatus. [Diagram 2] FIG. 1 is a diagram for explaining the types of samples in Examples 1 to 9. [Diagram 3] FIG. 1 is a diagram for explaining the types of samples of Comparative Example 1 to Comparative Example 9. [Figure 4] FIG. 13 is a diagram showing the measurement results of the sound absorption coefficient of Examples 1 to 9. [Diagram 5] FIG. 13 is a graph showing the measurement results of the sound absorption coefficients of Comparative Examples 1 to 9. [Figure 6] Graph showing the measurement results of the sound absorption coefficient of Example 1. [Figure 7] Graph showing the measurement results of the sound absorption coefficient of Example 2. [Figure 8] 13 is a graph showing the measurement results of the sound absorption coefficient of Example 3. [Figure 9] Graph showing the measurement results of the sound absorption coefficient of Example 4. [Figure 10] 13 is a graph showing the measurement results of the sound absorption coefficient of Example 5. [Figure 11] Graph showing the measurement results of the sound absorption coefficient of Example 6. [Figure 12] 13 is a graph showing the measurement results of the sound absorption coefficient of Example 7. [Figure 13] Graph showing the measurement results of the sound absorption coefficient of Example 8. [Figure 14] Graph showing the measurement results of the sound absorption coefficient of Example 9. [Figure 15] 1 is a graph showing the measurement results of the sound absorption coefficient of Comparative Example 1. [Figure 16] 13 is a graph showing the measurement results of the sound absorption coefficient of Comparative Example 2. [Figure 17] 13 is a graph showing the measurement results of the sound absorption coefficient of Comparative Example 3. [Figure 18] 13 is a graph showing the measurement results of the sound absorption coefficient of Comparative Example 4. [Figure 19] 13 is a graph showing the measurement results of the sound absorption coefficient of Comparative Example 5. [Figure 20] 13 is a graph showing the measurement results of the sound absorption coefficient of Comparative Example 6. [Figure 21] 13 is a graph showing the measurement results of the sound absorption coefficient of Comparative Example 7. [Figure 22] 13 is a graph showing the measurement results of the sound absorption coefficient of Comparative Example 8. [Diagram 23]13 is a graph showing the measurement results of the sound absorption coefficient of Comparative Example 9. [Figure 24] FIG. 1 is a graph showing the average sound absorption coefficient from 500 Hz to 1000 Hz of Examples 1 to 9. [Diagram 25] FIG. 13 is a graph showing the average sound absorption coefficient from 500 Hz to 1000 Hz of Comparative Example 1 to Comparative Example 9. [Figure 26] 1 is a diagram showing the relationship between the thickness of a sound-absorbing board and the average sound absorption coefficient. [Figure 27] Graph showing the relationship between the thickness of a sound-absorbing board and the average sound absorption coefficient. [Figure 28] Graph showing the relationship between the thickness of a sound-absorbing board and the average sound absorption coefficient. [Figure 29] Graph showing the relationship between the thickness of a sound-absorbing board and the average sound absorption coefficient. [Diagram 30] Graph showing the relationship between the thickness of a sound-absorbing board and the average sound absorption coefficient. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] As shown in Fig. 1, the board manufacturing apparatus 1 manufactures a sound-absorbing board M from a raw material Sa. The sound-absorbing board M can be used, for example, as an interior wall material for houses, offices, music halls, etc. The sound-absorbing board M can also be used, for example, as a partition or partition in an office.

[0008] Examples of the fiber-containing raw material Sa to be supplied to the board manufacturing apparatus 1 include paper, cardboard, pulp, pulp sheets, sawdust, shavings, and wood. By defibrating these raw materials, cellulose fibers are generated as the defibrated material. Cellulose fibers are fibers contained in plant fibers such as wood, and are carbohydrates. Polyester fibers can also be used as the defibrated material. For example, polyester cloth scraps can be used as the raw material Sa to generate polyester fibers as the defibrated material.

[0009] Such fiber-containing raw material Sa is fed into a crusher 10 of a board manufacturing apparatus 1, where the crusher blades 11 of the crusher 10 break the fiber-containing raw material Sa into crushed pieces Sr of several centimeters square. The process of breaking the raw material Sa into crushed pieces Sr by the crusher 10 is called the crushing process. Such a crusher 10 is preferably provided with an automatic feed mechanism 5 for continuously feeding the fiber-containing raw material Sa. The feeding speed of the automatic feed mechanism 5 should be high in terms of productivity.

[0010] This can be achieved by using a device in which the crushing blade 11 in the crusher 10 has a wider cutting width than the blade of a normal shredder. The crushed pieces Sr broken into pieces several centimeters square by the crushing blade 11 are introduced into the next process, the defibration process, through the constant-volume feeder 50 from the hopper 12 via the introduction pipe 20. The constant-volume feeder 50 may be of any type as long as it can feed material into the defibrator 30 in a constant volume, but a vibrating feeder is preferred.

[0011] The introduction pipe 20 communicates with an introduction port 31 of the defibrator 30. The coarsely crushed pieces Sr introduced into the defibrator 30 from the introduction port 31 are defibrated between the rotating rotor 34 and the stator 33. The defibrator 30 defibrates the input coarsely crushed pieces Sr into a cotton-like state. The process of defibrating the coarsely crushed pieces Sr by the defibrator 30 is called the defibration process. The defibrated material defibrated by the defibrator 30 is called defibrated fiber Fm. The defibrator 30 also has a mechanism for generating an airflow. The defibrated fibers are carried by the airflow generated by the defibrator 30 and are guided from the discharge port 32 to the transport pipe 40 constituting the transport section.

[0012] The airflow from the defibrator 30 sucks the coarsely crushed pieces Sr into the interior of the defibrator 30 through the inlet 31. If the defibrator 30 does not have a mechanism for generating an airflow, a blower or the like that generates an airflow can be added. The airflow generated by the blower guides the coarsely crushed pieces Sr to the inlet 31. The defibrated fibers Fm discharged from the defibrator 30 are guided to the deposition section 100 via the transport pipe 40. The defibrated fibers Fm fed from the defibrator 30 into the transport pipe 40 are also referred to as first fibers F1.

[0013] A hopper 13 is connected to the conveying pipe 40. The hopper 13 is connected to the conveying pipe 40 via a supply pipe 61 and a valve 65. The thermally molten fiber Fs is fed into the hopper 13. The thermally molten fiber Fs fed into the hopper 13 is fed to the conveying pipe 40 via the supply pipe 61. The thermally molten fiber Fs is also called the second fiber F2. The valve 65 opens and closes the supply pipe 61. When the valve 65 is open, the thermally molten fiber Fs is fed to the conveying pipe 40 via the supply pipe 61. When the valve 65 is closed, the supply of the thermally molten fiber Fs to the conveying pipe 40 is stopped. When the thermally molten fiber Fs is fed to the conveying pipe 40, the defibrated fiber Fm and the thermally molten fiber Fs are mixed inside the conveying pipe 40. The process of feeding the thermally molten fiber Fs to the conveying pipe 40 is called the mixing process. In the following, the mixture of the defibrated fiber Fm and the thermally molten fiber Fs is called the mixed fiber Fk. The mixed fiber Fk is introduced into the deposition section 100 through the transport pipe 40.

[0014] The thermally melting fiber Fs may be a composite fiber with a sheath-core structure. The composite fiber with a sheath-core structure has a structure in which the core is covered with a thermoplastic resin. The thermoplastic resin corresponds to the sheath of the sheath-core structure. The core is a fiber. Examples of fibers constituting the core include natural fibers such as cellulose fibers, and synthetic fibers such as polyester and rayon. In this embodiment, polyethylene terephthalate is used as the core. Examples of thermoplastic resins constituting the sheath include polyethylene, polypropylene, polyvinyl chloride, polyurethane, polystyrene, acrylic resin, and polyvinyl acetate. In this embodiment, polyethylene is used as the sheath.

[0015] The deposition unit 100 has a forming drum 101 and a case 102. The forming drum 101 is accommodated inside the case 102. The deposition unit 100 disperses the mixed fiber Fk from the forming drum 101 into the atmosphere inside the case 102. A mesh belt 122 and a suction device 110 are disposed below the deposition unit 100. Here, a first substrate N1 is supplied between the deposition unit 100 and the mesh belt 122. The mixed fiber Fk dispersed into the atmosphere from the forming drum 101 is deposited on the first substrate N1 on the mesh belt 122. The process of depositing the mixed fiber Fk on the first substrate N1 by the deposition unit 100 and the suction device 110 is called the deposition process. In this embodiment, the deposition method in the deposition process is an air-laid method. The air-laid method is a method of depositing fibers by uniformly dispersing them with an air flow.

[0016] The first substrate N1 is unwound from the roll 81 and then supplied between the deposition section 100 and the mesh belt 122. The mixed fibers Fk deposited on the first substrate N1 form the web S. The first substrate N1 supplied from the roll 81 onto the mesh belt 122 becomes a base section that supports the web S. Here, the first substrate N1 can be, for example, either a woven fabric or a nonwoven fabric. The first substrate N1 is, for example, a long-fiber nonwoven fabric made of polyester or cellulose produced by a spunbond method.

[0017] The forming drum 101 is a cylindrical sieve that is rotated by a motor (not shown). A mesh having a sieve function is provided on the side of the cylindrical forming drum 101. The forming drum 101 disperses the mixed fiber Fk into the air in the case 102 through the mesh of the sieve. The mesh belt 122 is an endless belt that is stretched around a tension roller 121. A plurality of holes are formed in the mesh belt 122. The suction device 110 is provided on the opposite side of the mesh belt 122 to the deposition section 100 side. In other words, the suction device 110 is located inside the mesh belt 122.

[0018] The suction device 110 sucks in the air through the mesh belt 122 and the first substrate N1. This allows the mixed fibers Fk dispersed in the air from the forming drum 101 to be sucked toward the first substrate N1. As a result, the mixed fibers Fk can be promoted to be deposited on the first substrate N1. The mesh belt 122 rotates clockwise as viewed in FIG. 1 due to the rotation of the tension roller 121. As the mesh belt 122 rotates, the mixed fibers Fk are continuously deposited on the first substrate N1 to form the web S. The web S is transported downstream as the mesh belt 122 rotates. The process of transporting the web S by the mesh belt 122 is called a transport process. Note that the mesh belt 122 has surface dirt and the like removed by a cleaning blade 123.

[0019] A heating and pressing mechanism 150 is provided downstream of the mesh belt 122 on the transport path of the web S. A second substrate N2 is supplied between the mesh belt 122 and the heating and pressing mechanism 150 on the transport path of the web S. The second substrate N2 is supplied on the opposite side of the web S to the first substrate N1. That is, the second substrate N2 is supplied to the upper side of the web S. The mixed fiber Fk deposited on the first substrate N1 in the deposition section 100 is sandwiched between the first substrate N1 and the second substrate N2. The second substrate N2 becomes a cover part of the upper surface of the web S. The second substrate N2 is unwound from the state of the roll 82 and then supplied between the mesh belt 122 and the heating and pressing mechanism 150 on the transport path of the web S. For example, either a woven fabric or a nonwoven fabric can be used as the second substrate N2. For example, the second substrate N2 is a long-fiber nonwoven fabric using polyester or cellulose manufactured by a spunbond method.

[0020] The web S sandwiched between the first substrate N1 and the second substrate N2 reaches the heating and pressurizing mechanism 150. The heating and pressurizing mechanism 150 has a first substrate 151 and a second substrate 152. The second substrate 152 is configured to be able to rise and fall relative to the first substrate 151. The first substrate 151 and the second substrate 152 each have a built-in heater. The web S is introduced between the first substrate 151 and the second substrate 152. The web S is sandwiched between the first substrate 151 and the second substrate 152. By sandwiching the web S between the first substrate 151 and the second substrate 152, the web S is heated and pressurized.

[0021] By heating and pressurizing the web S, the thermoplastic resin of the heat-melting fibers Fs contained in the mixed fibers Fk binds the mixed fibers Fk. The thermoplastic resin also bonds the web S to the first base material N1 and also bonds the web S to the second base material N2. The process of heating and pressurizing the web S by the heating and pressurizing mechanism 150 is called the molding process. Since the molding process is a batch process, it is desirable to provide a buffer upstream of the heating and pressurizing mechanism 150 on the transport path of the web S in order to ensure the heating time. The buffer can be realized by raising and lowering the so-called dancer roller 141.

[0022] A cutter 160 is provided downstream of the heating and pressurizing mechanism 150 on the transport path of the web S. The cutter 160 cuts the web S to a predetermined length. In this way, a sound-absorbing board M is formed from the web S. The process of cutting the web S with the cutter 160 is called the cutting process. The sound-absorbing board M cut from the web S is loaded onto a stacker 170. The sound-absorbing board M is cooled while loaded onto the stacker 170. The sound-absorbing board M manufactured by the board manufacturing apparatus 1 can be used as a sound-absorbing board.

[0023] The sound absorbing performance of the sound absorbing board M will be described. The sound absorbing performance was evaluated using the sound absorbing board M manufactured by the board manufacturing device 1 as a sample. Samples of the sound absorbing board M are shown in Figs. 2 and 3. As shown in Fig. 2, nine types of samples, Example 1 to Example 9, were prepared as samples of the embodiment. Also, as shown in Fig. 3, nine types of samples, Comparative Example 1 to Comparative Example 9, were prepared as samples of the comparative example. The sound absorption coefficient was measured for eight types of the embodiment and eight types of the comparative example. The measured sound absorption coefficient is the random incident sound absorption coefficient. The method for measuring the random incident sound absorption coefficient was in accordance with JIS A 1405-2 "Measurement of sound absorption coefficient and impedance by acoustic tube". In addition, the measuring instrument used was "WinZacMTX" manufactured by Nihon Onkyo Engineering Co., Ltd. The random incident sound absorption coefficient is one index that indicates sound absorbing performance. The closer the random incident sound absorption coefficient is to 1, the higher the sound absorbing performance is.

[0024] The measurement results of the sound absorption coefficient of Examples 1 to 9 are shown in FIG. 4. The measurement results of the sound absorption coefficient of Comparative Examples 1 to 9 are shown in FIG. 5. The measurement results of the sound absorption coefficient of Example 1 are shown as a graph in FIG. 6. The measurement results of the sound absorption coefficient of Example 2 are shown as a graph in FIG. 7. The measurement results of the sound absorption coefficient of Example 3 are shown as a graph in FIG. 8. The measurement results of the sound absorption coefficient of Example 4 are shown as a graph in FIG. 9. The measurement results of the sound absorption coefficient of Example 5 are shown as a graph in FIG. 10. The measurement results of the sound absorption coefficient of Example 6 are shown as a graph in FIG. 11. The measurement results of the sound absorption coefficient of Example 7 are shown as a graph in FIG. 12. The measurement results of the sound absorption coefficient of Example 8 are shown as a graph in FIG. 13. The measurement results of the sound absorption coefficient of Example 9 are shown as a graph in FIG. 14.

[0025] The measurement results of the sound absorption coefficient of Comparative Example 1 are shown as a graph in FIG. 15. The measurement results of the sound absorption coefficient of Comparative Example 2 are shown as a graph in FIG. 16. The measurement results of the sound absorption coefficient of Comparative Example 3 are shown as a graph in FIG. 17. The measurement results of the sound absorption coefficient of Comparative Example 4 are shown as a graph in FIG. 18. The measurement results of the sound absorption coefficient of Comparative Example 5 are shown as a graph in FIG. 19. The measurement results of the sound absorption coefficient of Comparative Example 6 are shown as a graph in FIG. 20. The measurement results of the sound absorption coefficient of Comparative Example 7 are shown as a graph in FIG. 21. The measurement results of the sound absorption coefficient of Comparative Example 8 are shown as a graph in FIG. 22. The measurement results of the sound absorption coefficient of Comparative Example 9 are shown as a graph in FIG. 23.

[0026] FIG. 24 shows the average sound absorption coefficients from 500 Hz to 1000 Hz for Example 1 to Example 9. All of Example 1 to Example 9 have an average sound absorption coefficient of 0.7 or more from 500 Hz to 1000 Hz. FIG. 25 shows the average sound absorption coefficients from 500 Hz to 1000 Hz for Comparative Example 1 to Comparative Example 9. All of Comparative Example 1 to Comparative Example 9 have an average sound absorption coefficient of less than 0.7 from 500 Hz to 1000 Hz. From these results, the relationship between the thickness of the sound-absorbing board M and the average sound absorption coefficient will be considered. FIG. 26 shows the relationship between the thickness of the sound-absorbing board M and the average sound absorption coefficient.

[0027] Fig. 27 is a graph showing the relationship between the thickness and the average sound absorption coefficient of the sound absorbing board M. Fig. 27 shows the relationship between the thickness and the average sound absorption coefficient of the sound absorbing board M when the first fiber F1 shown in Fig. 1 is a polyester fiber and the density of the sound absorbing board M is 0.2 g / cm 3 27 shows the relationship between the thickness of sound-absorbing board M and the average sound absorption coefficient when the thickness is within the range of 20 mm to 40 mm. As shown in Fig. 27, if the thickness of sound-absorbing board M is within the range of 20 mm to 40 mm, the average sound absorption coefficient exceeds 0.7. If the thickness of sound-absorbing board M is 10 mm, the average sound absorption coefficient falls below 0.7.

[0028] Fig. 28 is a graph showing the relationship between the thickness and the average sound absorption coefficient of the sound absorbing board M. In Fig. 28, the first fiber F1 shown in Fig. 1 is a polyester fiber, and the density of the sound absorbing board M is 0.24 g / cm 3 28 shows the relationship between the thickness of sound-absorbing board M and the average sound absorption coefficient when the thickness is within the range of 20 mm to 30 mm. As shown in Fig. 28, when the thickness of sound-absorbing board M is within the range of 20 mm to 30 mm, the average sound absorption coefficient exceeds 0.7. When the thickness of sound-absorbing board M is 10 mm and 40 mm, the average sound absorption coefficient falls below 0.7.

[0029] Fig. 29 is a graph showing the relationship between the thickness and the average sound absorption coefficient of the sound absorbing board M. Fig. 29 shows the relationship between the thickness and the average sound absorption coefficient of the sound absorbing board M when the first fiber F1 shown in Fig. 1 is a cellulose fiber and the density of the sound absorbing board M is 0.12 g / cm 329 shows the relationship between the thickness of sound-absorbing board M and the average sound absorption coefficient when the thickness is within the range of 20 mm to 25 mm. As shown in Fig. 29, when the thickness of sound-absorbing board M is within the range of 20 mm to 25 mm, the average sound absorption coefficient exceeds 0.7. When the thickness of sound-absorbing board M is 10 mm and 30 mm, the average sound absorption coefficient falls below 0.7.

[0030] Fig. 30 is a graph showing the relationship between the thickness and the average sound absorption coefficient of the sound absorbing board M. In Fig. 30, the first fiber F1 shown in Fig. 1 is a cellulose fiber, and the density of the sound absorbing board M is 0.24 g / cm 3 30 shows the relationship between the thickness of the sound-absorbing board M and the average sound absorption coefficient when the thickness of the sound-absorbing board M is 10 mm to 40 mm. As shown in Fig. 30, the average sound absorption coefficient is below 0.7 for all thicknesses of the sound-absorbing board M from 10 mm to 40 mm.

[0031] From the above Examples 1 to 9 and Comparative Examples 1 to 9, the following points can be derived. The following points can be derived regarding the sound-absorbing board M made of a material containing polyester fibers and heat-melting fibers Fs containing a thermoplastic resin that is bonded to the polyester fibers. Density is 0.2g / cm 3 More than 0.24g / cm 3 According to the sound absorbing board M having a thickness of 20 mm to 30 mm, the random incident sound absorption coefficient can be increased to 0.7 or more on average in the frequency band of incident sound waves from 500 Hz to 1000 Hz. As a result, the sound absorption coefficient can be improved in the frequency band of voices uttered by adult males and females.

[0032] The following points can be derived regarding the sound-absorbing board M made of a material containing cellulose fibers and heat-melting fibers Fs containing a thermoplastic resin that is bonded to the cellulose fibers. Density 0.12g / cm 3 With the sound-absorbing board M having a thickness of 20 mm to 25 mm, the random incident sound absorption coefficient can be increased to 0.7 or more on average in the frequency band of incident sound waves from 500 Hz to 1000 Hz. As a result, the sound absorption coefficient can be improved in the frequency band of voices uttered by adult males and females.

[0033] The density of the sound-absorbing board M can be controlled by controlling the amount of the mixed fibers Fk deposited in the depositing step and the pressure applied to the web S in the molding step. In the present embodiment, the manufacturing method of the sound-absorbing board M includes a fiber-opening step. However, a manufacturing method of the sound-absorbing board M that omits the fiber-opening step can also be applied. The first fibers F1 manufactured in another manufacturing step can be used as the raw material of the sound-absorbing board M. In this case, the automatic feed mechanism 5, the crusher 10, the crusher blade 11, and the fiber-opening machine 30 shown in FIG. 1 can be omitted from the board manufacturing apparatus 1. The first fibers F1 are then fed into the hopper 12. A manufacturing error is allowed for the thickness of the sound-absorbing board M. The allowable error is ±10%. [Explanation of symbols]

[0034] 1...board manufacturing device, 5...automatic feed mechanism, 10...crusher, 11...crusher blade, 12...hopper, 13...hopper, 20...inlet pipe, 30...fibrillator, 31...inlet port, 32...discharge port, 33...stator, 34...rotor, 40...conveyor pipe, 50...quantitative feeder, 61...feed pipe, 65...valve, 81...roll, 82...roll, 100...accumulation section, 101...forming drum, 102...case, 110...suction device, 1 21...tension roller, 122...mesh belt, 123...cleaning blade, 141...dancer roller, 150...heating and pressurizing mechanism, 151...first substrate, 152...second substrate, 160...cutter, 170...stacker, F1...first fiber, F2...second fiber, Fk...mixed fiber, Fm...defibrated fiber, Fs...thermal melt fiber, N1...first base material, N2...second base material, M...sound-absorbing board, S...web, Sa...raw material, Sr...coarsely crushed pieces.

Claims

[Claim 1] A sound-absorbing board made of a material including polyester fibers and heat-melting fibers including a thermoplastic resin bonded to the polyester fibers, Density: 0.2 g / cm 3 to 0.24 g / cm 3 and The thickness is 20 mm to 30 mm. Sound absorbing board.

Images