Automobile sound insulation materials

Abstract

The present invention provides a sound insulation material for automobiles, which can achieve lightweight while exhibiting sufficient sound insulation performance against noise of 500 Hz to 6400 Hz generated in automobiles. The sound insulation material for automobiles of the present invention comprises a core layer (10) having cylindrical cells (20) arranged in multiple rows, an airtight resin film layer (40) provided on one surface of the core layer, and a decoupling layer (30) provided on the outer side thereof; the cell ends on one surface of the core layer have closed surfaces (21) and open ends (22) in a row-by-row manner; the cell ends on the other surface of the core layer have open ends in the row with the closed surfaces of the cell ends on the one surface, and have closed surfaces in the row with the open ends of the cell ends on the other surface, and the internal space of the cells is connected to the outside through the open ends; the average value of (P / v) / Za represented by the sound pressure P at the surface of the airtight resin film layer provided on the core layer opposite to the core layer, the sound particle velocity v, and the acoustic impedance Za of the decoupling layer is 2.8 to 10 between 500 Hz and 6400 Hz.

Description

Technical Field

[0001] The present invention relates to a sound insulating material for automobiles, and more particularly to a sound insulating material for automobiles having sound absorbing properties. Background Art

[0002] The structure of an automobile generally consists of an engine compartment at the front, a trunk compartment at the rear, and a passenger compartment located between them. The passenger compartment houses seats such as the driver's seat, the front passenger seat, and the rear seats. Furthermore, the passenger compartment includes a front bulkhead insulator, carpets, floor mats, a trunk trim, and a trunk floor covering to cover the outside of the vehicle's interior components. These components are formed into concave and convex shapes that correspond to the shape of the vehicle body or the design of the components. Furthermore, the exterior components under the vehicle body include a front fender lining, a rear fender lining, and an undercover formed into a concave and convex shape to control air flow. These components are often made of thermoplastic resin, which is heated and stamped using a mold in the shape of the component, resulting in a finished component with multiple concave and convex sections of varying thickness.

[0003] As a recent trend in automobile development, interior quietness is gaining increasing attention. Noise transmitted into the vehicle interior includes noise from the windows, tires, under the vehicle body, engine noise, and motor noise. Frequencies between 500Hz and 4000Hz are particularly perceived as harsh to the driver and passengers. Furthermore, in electric vehicles, frequencies between 4000Hz and 8000Hz, which were previously considered less harsh, are now considered harsh to the driver and passengers due to the lack of an engine. Therefore, automotive interior and exterior components are required to absorb noise in this frequency range. Furthermore, reducing the weight of automotive interior and exterior components is also crucial to improving fuel efficiency.

[0004] Furthermore, Japanese Patent Application Laid-Open No. 2005-99402 describes a sound absorbing structure comprising a first sound absorbing portion and a second sound absorbing portion. The first sound absorbing portion is formed from a material having an acoustic impedance substantially equal to or slightly greater than that of air, and the second sound absorbing portion is formed from a material having an acoustic impedance greater than that of the first sound absorbing portion. This publication describes the following: when the acoustic impedance of a sound absorbing layer differs significantly from that of air, most incident sound waves are reflected at the interface between the sound absorbing layer and the air layer, i.e., the surface of the sound absorbing layer. However, by setting the acoustic impedance of the first sound absorbing layer, which forms the interface with the air layer, to the aforementioned value, most incident sound waves reach the second sound absorbing layer without being reflected at the surface of the first sound absorbing layer. Furthermore, the discontinuity in acoustic impedance between the first and second sound absorbing layers is minimized. Consequently, reflection of a portion of incident sound waves at the interface between the first and second sound absorbing layers due to the difference in acoustic impedance can be minimized.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2005-99402 Summary of the Invention

[0008] Problems to be solved by the present invention

[0009] As mentioned above, automotive sound insulation materials achieve sound insulation by reflecting incident sound waves by increasing the difference in acoustic impedance between air and layers, and between layers themselves. Acoustic impedance varies significantly depending on the layer structure; for example, fiber layers have relatively low acoustic impedance, while rubber layers have relatively high acoustic impedance. Therefore, while using a rubber layer in sound insulation improves sound insulation, it increases the weight of the material, posing a challenge for automotive use.

[0010] Therefore, an object of the present invention is to provide a sound insulating material for automobiles that can achieve lightweighting while ensuring high rigidity and exhibit sufficient sound insulating performance against noise generated in automobiles, particularly noise with a frequency of 500 Hz to 6400 Hz.

[0011] Means used to solve problems

[0012] To achieve the above objectives, the present invention provides a multi-layered automotive sound insulation material comprising a core layer, a first air-impermeable resin film layer, and a decoupling layer. The core layer comprises cylindrical units arranged in multiple rows, the first air-impermeable resin film layer is disposed on at least one surface of the core layer, and the decoupling layer is disposed on a surface of the first air-impermeable resin film layer opposite to the core layer. In the automotive sound insulation material, an average value of a specific acoustic impedance ratio (expressed as sound pressure P and sound particle velocity v on a surface of the first air-impermeable resin film layer disposed on the core layer opposite to the core layer, and an average value of an acoustic impedance ratio (Za) of the decoupling layer, expressed as sound pressure P and sound particle velocity v on a surface of the first air-impermeable resin film layer disposed on the core layer opposite to the core layer, is 2.8 < (P / v) / Za < 10 between 500 Hz and 6400 Hz.

[0013] The tubular unit may be a polygonal tubular shape such as a roughly quadrangular tubular shape or a roughly hexagonal tubular shape, or a curved tubular shape such as a roughly cylindrical shape or a roughly elliptical tubular shape. Preferably, each of the units in the core layer has a closed surface at one end and an open end at the other end, the internal space of the unit is connected to the outside through the open end of the unit, and the open ends of the unit are arranged in a row of adjacent units on both surfaces of the core layer. Depending on the shape of the unit, the open end, the closed surface on one side, and the closed surface on the other side may be a polygonal shape such as a roughly quadrangular shape or a roughly hexagonal shape, or a curved shape such as a roughly circular shape or a roughly elliptical shape.

[0014] The thickness of the first air-impermeable resin film layer of the core layer of the automobile sound insulation material of the present invention is preferably 50 to 200 μm.

[0015] The automobile sound insulating material of the present invention may further include a resin film layer having a plurality of openings, the resin film layer being bonded to a surface of the core layer opposite to a surface to which the first air-impermeable resin film layer is bonded.

[0016] The pitch Pcy between the cells in the core layer in the direction of the row formed by the adjacent cells is preferably 10 mm or less.

[0017] The first air-impermeable resin film layer may have a structure formed by laminating a plurality of different materials.

[0018] Effects of the Invention

[0019] Thus, the automotive sound insulation material of the present invention comprises a core layer having multiple rows of cylindrical cells, a first air-impermeable resin film layer, and a decoupling layer. The core layer comprises a plurality of cylindrical cells arranged in rows. The first air-impermeable resin film layer is provided on at least one surface of the core layer, and the decoupling layer is provided on the surface of the first air-impermeable resin film layer opposite the core layer. The average value of the acoustic impedance ratio, represented by the sound pressure P and the sound particle velocity v at the surface of the first air-impermeable resin film layer opposite the core layer, and the acoustic impedance Za of the decoupling layer, is set to 2.8 < (P / v) / Za < 10 between 500 Hz and 6400 Hz. This technical solution not only ensures high rigidity while achieving lightweight automotive sound insulation material, but also provides sufficient sound insulation performance against vehicle noise because sound waves with frequencies of 500 Hz to 6400 Hz generated in a vehicle are largely reflected at the interface between the decoupling layer and the first air-impermeable resin film layer after entering the decoupling layer.

[0020] By setting the thickness of the first air-impermeable resin film layer to 50 to 200 μm, it is possible to maintain the above-mentioned sound insulation performance while reducing weight.

[0021] Based on the fact that a resin film layer having a plurality of openings is provided on the surface of the core layer opposite to the first airtight resin film layer, and by pre-forming an opening pattern on the resin film layer having a plurality of openings, the degree of closure of the open end of at least one surface of the core layer can be easily adjusted and stably maintained, thereby being able to control the peak value of the sound absorption rate of the automotive sound insulation material, thereby being able to exhibit excellent sound absorption performance while exhibiting the above-mentioned sound insulation performance.

[0022] Since the first air-impermeable resin film layer is configured by laminating a plurality of different materials, it is possible to easily design so that the acoustic impedance ratio (P / v) / Za falls within a predetermined range.

[0023] Each unit of the core layer has a closed surface at one end and an open end at the other end, and the internal space of the unit is connected to the outside through the open end of the unit. The open ends of the unit are arranged on both surfaces of the core layer in a row separated by a row of adjacent units. Based on this structural configuration, it is possible to ensure that the closed surface of the core layer unit becomes the bonding surface between the first airtight resin film layer and the core layer, and the closed surface of the unit is arranged in a row separated by a row, thereby improving the adhesion between the first airtight resin film layer and the core layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a perspective view showing a process for producing a core material used for a core layer in the automobile sound insulating material of the present invention.

[0025] Figure 2This is a schematic plan view showing the core layer of the automobile sound insulating material of the present invention.

[0026] Figure 3 It shows Figure 2 Schematic cross-sectional view of the core layer along line III-III.

[0027] Figure 4 This is an exploded perspective view showing one embodiment of the automobile sound insulating material of the present invention.

[0028] Figure 5 yes Figure 4 A schematic cross-sectional view of an embodiment of a sound insulating material for an automobile is shown.

[0029] Figure 6 This is an exploded perspective view showing another embodiment of the automobile sound insulating material of the present invention.

[0030] Figure 7 This is a schematic cross-sectional view showing still another embodiment of the automobile sound insulating material of the present invention.

[0031] Figure 8 This is an exploded perspective view showing still another embodiment of the automobile sound insulating material of the present invention.

[0032] Figure 9 This is a graph showing the relationship between the surface density and the acoustic impedance ratio of examples and comparative examples of the automobile sound insulating material of the present invention.

[0033] Figure 10 This is a graph showing the relationship between frequency and sound transmission loss in Examples and Comparative Examples of the automobile sound insulating material of the present invention. DETAILED DESCRIPTION

[0034] Hereinafter, an embodiment of the automobile sound insulating material according to the present invention will be described with reference to the accompanying drawings. The accompanying drawings are not drawn to scale unless otherwise specified.

[0035] First, the core layer common to each embodiment of the automobile sound insulating material according to the present invention will be described. Figure 1 2 is a perspective view showing a process for manufacturing a core material that becomes the core layer. WO 2006 / 053407 describes in detail a method for manufacturing the core material, which is incorporated herein by reference.

[0036] like Figure 1As shown, the core material 1 is formed by thermoforming a flat sheet material using a roller (not shown) having a predetermined mold, and is formed by plastic deformation without substantially cutting the sheet material. The material of the core material 1 can be, for example, thermoplastic resins such as polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), and composite materials with fibers, paper, metal, etc., and thermoplastic resins are particularly preferred, but are not limited to these. In this embodiment, the case of using thermoplastic resins is described. The thickness of the sheet material is preferably in the range of 0.05 mm to 0.50 mm, for example, but is not limited thereto, and the thickness of the core material 1 after thermoforming is also roughly the same.

[0037] The core material 1 has a three-dimensional structure in which mountain portions 11 and valley portions 12 are alternately arranged in the width direction X perpendicular to the manufacturing direction Y. The mountain portion 11 is composed of two side surfaces 13 and a top surface 17 therebetween, and the valley portion 12 is composed of two side surfaces 13 shared with adjacent mountain portions 11 and a bottom surface 14 therebetween. Figure 1 The case where the shape of the mountain portion 11 is a trapezoid is described, but the present invention is not limited thereto. In addition to polygons such as a triangle and a rectangle, a curved shape such as a sine curve or an arcuate shape may also be used.

[0038] The core material 1 has the three-dimensional structure that is continuous in the manufacturing direction Y. Figure 1 As shown, a plurality of peaks 11a, 11b, 11c, and 11d are formed continuously in the manufacturing direction Y. The valleys 12 are also formed continuously. The connection between the peaks 11 and the connection between the valleys 12 are achieved by alternately repeating two connection methods.

[0039] The first connection method is as follows Figure 1 As shown, on the first folding line X1 in the width direction, the top surfaces 17b and 17c of the two adjacent mountain portions 11b and 11c are connected by trapezoidal mountain portion connecting surfaces 15b and 15c, respectively. The mountain portion connecting surface 15 is formed at a right angle to the top surface 17. On the first folding line X1 in the width direction, the bottom surfaces 14b and 14c of the two adjacent valley portions are directly connected. The second connection method is as follows Figure 1 As shown, along the second widthwise fold line X2, the bottom surfaces 14a, 14b (or 14c, 14d) of two adjacent valley portions are connected by trapezoidal valley connecting surfaces 16a, 16b (or 16c, 16d), respectively. Valley connecting surfaces 16 are formed at right angles to bottom surface 14. Along this second widthwise fold line X2, the top surfaces 12a, 12b (or 12c, 12d) of two adjacent mountain portions are directly connected.

[0040] In this way, the multiple three-dimensional structures (mountains 11 and valleys 12) of the core material 1 are connected by connecting regions (mountain connecting surfaces 15 and valley connecting surfaces 16). By folding these connecting regions, the core layer of the automotive sound insulation material of the present invention is formed. Specifically, the core material 1 is folded along a first fold line X1 using a mountain fold so that the bottom surfaces 14b and 14c of two adjacent valleys overlap with each other and the angle formed by the mountain connecting surfaces 15b and 15c of the two adjacent peaks is open to 180 degrees. Furthermore, along a second fold line X2 using a valley fold so that the top surfaces 17a and 17b (or 17c and 17d) of two adjacent peaks overlap with each other and the angle formed by the valley connecting surfaces 16a and 16b (or 16c and 16d) of the two adjacent valleys is closed to 180 degrees. Figure 2 and Figure 3 The core layer 10 of the automobile sound insulating material of the present invention obtained by folding the core material 1 in this manner is shown.

[0041] like Figure 2 and Figure 3 As shown, the core layer 10 includes substantially hexagonal cylindrical units 20 arranged in a plurality of rows, with units 20A, 20C, and 20E formed by two adjacent peaks and units 20B and 20D formed by two adjacent valleys arranged in alternate rows. Figure 3 (and Figure 2 The dotted line 18 in the figure schematically shows the inner wall of the unit 20 which is the back surface (inner side) of the core material and is substantially in the shape of a hexagonal cylinder.

[0042] The units 20A, 20C, and 20E formed by the mountain portion each have six unit side walls forming a substantially hexagonal cylindrical shape, and these unit side walls are formed by the two top surfaces 17 and four side surfaces 13 of the unit material. In addition, these units 20A, 20C, and 20E are formed on one surface 10a ( Figure 2 (and Figure 3 The cell ends (the surface side in the relevant) are each provided with a generally hexagonal cylindrical closed surface 21A, 21C, and 21E for closing the cell ends. These closed surfaces 21 on one side are formed by two trapezoidal mountain connecting surfaces 15 of the cell material. In addition, these cells 20A, 20C, and 20E have a generally hexagonal open end 22A, 22C, and 22E at the cell end on the other surface 10b of the core layer 10, which is the opposite side. The internal space of each cell 20A, 20C, and 20E communicates with the outside through these open ends 22A, 22C, and 22E.

[0043] The units 20B and 20D formed by the valley also have six unit side walls that form a roughly hexagonal cylindrical shape, and these unit side walls are formed by the two bottom surfaces 14 and four side surfaces 13 of the unit material. In addition, these units 20B and 20D have open ends 22B and 22D that open into a roughly hexagonal shape at the unit end of the one surface 10a of the core layer 10. The internal space of each unit 20B and 20D is connected to the outside through the open ends 22B and 22D. In addition, these units 20B and 20D have respectively roughly hexagonal cylindrical closed surfaces 21B and 21D that close the unit end at the unit end of the other surface 10b on the opposite side of the core layer 10, and these closed surfaces 21 on the other side are respectively formed by two trapezoidal valley connecting surfaces 16 in the unit material.

[0044] In this way, the core layer 10 has a side closed surface 21A, 21C, 21E formed by the mountain part of the unit material in every other row at the unit end of one surface 10a, and has another side closed surface 21B, 21D formed by the valley part of the unit material in the row of units different from the above-mentioned units at the unit end of the other surface 10b, but unless otherwise stated, either one side closed surface or the other side closed surface 21 essentially performs the same function.

[0045] The overall thickness of the core layer 10 varies depending on the part of the automobile in which the multilayer structure is used. Therefore, from the perspective of controlling the acoustic impedance ratio between the airtight resin film layer and the decoupling layer described later, the sound absorption performance of the core layer 10 itself, the strength and weight of the core layer 10, the overall thickness of the core layer 10 is preferably in the range of 3 mm to 50 mm, more preferably in the range of 5 mm to 30 mm, but is not limited to these.

[0046] The basis weight (weight per unit area) of the core layer 10 varies depending on where the multilayer structure is used in the automobile, and is preferably 400 g / m 2 ~4000g / m 2 range, more preferably 500g / m 2 ~3000g / m 2 The greater the thickness and basis weight of the core layer 10, the higher the strength of the core layer 10.

[0047] The basis weight of the core layer 10 can be adjusted not only by the material type of the core layer 10, the overall thickness of the core layer 10, and the wall thickness (sheet thickness) of the cells 20, but also by the spacing Pcx and Pcy between the cells 20 (the distance between the center axes of the cells). To ensure that the basis weight of the core layer 10 is within the above range, for example, the spacing Pcy between the cells 20 in the core manufacturing direction Y, i.e., the direction in which the cells 20 are adjacent to form a row, is preferably set in the range of 3 mm to 20 mm, and more preferably in the range of 4 mm to 15 mm. In particular, to control the acoustic impedance ratio between the airtight resin film layer and the decoupling layer (described later) within a specified range, it is more preferable to set the spacing Pcy between the cells 20 to be 10 mm or less.

[0048] Next, each embodiment of the automobile sound insulating material according to the present invention will be described using the core layer 10 described above.

[0049] (First embodiment)

[0050] like Figure 4 and Figure 5 As shown, the automobile sound insulation material of the first embodiment includes: the core layer 10 described above; an airtight resin film layer 40 provided on one surface of the core layer 10; and a decoupling layer 30 further provided on the outer side of the airtight resin film layer 40. The automobile sound insulation material of the present invention is used so that the decoupling layer 30 is located on the side of the noise source.

[0051] The material of the airtight resin film layer 40 may be, for example, resin films such as polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), and polyamide (PA), but is not limited thereto.

[0052] The thickness of the air-impermeable resin film layer 40 varies depending on the acoustic impedance ratio between the air-impermeable resin film layer and the decoupling layer (described later). For example, its lower limit is preferably 0.02 mm or greater, more preferably 0.05 mm or greater, and even more preferably 0.1 mm or greater. The upper limit is preferably 0.6 mm or less, more preferably 0.4 mm or less, and even more preferably 0.3 mm or less.

[0053] The airtight resin film layer 40 can be bonded to the core layer 10 by heat fusion or by an adhesive (not shown). As the adhesive, for example, epoxy, acrylic, or other adhesives can be used, but there is no particular limitation. In addition, in order to heat fusion-bond the airtight resin film layer 40 to the core layer 10 and the decoupling layer 30, the airtight resin film layer 40 can be made into a three-layer structure, for example, with a central layer and two adhesive layers located on both sides thereof. In this case, the material of the adhesive layer uses a material with a lower melting point than the material used for the central layer. For example, by using polyamide with a melting point of 190°C to 220°C for the center layer and polyethylene with a melting point of 90°C to 130°C for the adhesive layer, the temperature during heating when attaching the air-impermeable resin film layer 40 to the core layer 10 and the decoupling layer 30, and the temperature during thermoforming of the automotive sound insulation material into a predetermined shape, can be set to approximately 150°C to 160°C. This allows only the adhesive layer to melt without melting the center layer, resulting in strong adhesion to the core layer 10 and the decoupling layer 30. In addition to polyamide, polypropylene is also an example of a resin with a higher melting point than the polyethylene of the adhesive layer.

[0054] The decoupling layer 30 is a layer generally used in automobile sound insulation materials as a layer for decoupling (cutting off) vibration transmission. There is no particular restriction on the raw materials of the decoupling layer 30, as long as it is a material that can be used for the decoupling layer of automobile sound insulation materials. However, from the perspective of lightweight automobile sound insulation materials, fibers such as synthetic fibers such as polyester fibers, nylon fibers, acrylic fibers, inorganic fibers such as glass wool and rock wool, and metal fibers such as aluminum fibers are preferred; and foams (foams) such as thermoplastic resins such as foamed polyurethane, foamed polyethylene, foamed nylon, and thermosetting resins are also preferred. Moreover, fibers and foams can be used in combination. In particular, as the decoupling layer 30, felt is preferred, and it is preferably formed from raw materials such as polyester fibers such as low-melting-point polyester fibers, glass wool, and the like. In addition, it is preferred that the felt be prepared by needle punching, hot rolling, hydroentanglement, or the like as a manufacturing method for the felt.

[0055] The basis weight of the decoupling layer 30 varies depending on the acoustic impedance ratio between the airtight resin film layer and the decoupling layer, and is not limited to the following, but its lower limit is preferably 10 g / m 2 More than 50 g / m 2 More preferably, 100 g / m 2 In addition, the upper limit of the basis weight is preferably 1000 g / m 2 Below, more preferably 800g / m 2 Below, more preferably 600g / m 2 The following, but not limited to these.

[0056] In an embodiment of the present invention, the average value of the acoustic impedance ratio (P / v) / Za (unit: dimensionless), represented by the sound pressure P and acoustic particle velocity v on the surface of the airtight resin film layer 40 opposite the core layer provided on the core layer 10, and the acoustic impedance Za of the decoupling layer 30, is in the range of 2.8 to 10 between 500 Hz and 6400 Hz. By setting the average value of the acoustic impedance ratio (P / v) / Za to 2.8 or greater, sound waves with a frequency of 500 Hz to 6400 Hz incident on the decoupling layer 30 can be sufficiently reflected at the interface between the decoupling layer 30 and the airtight resin film layer 40. Furthermore, by controlling the average value of the acoustic impedance ratio (P / v) / Za to 10 or less, the aforementioned sound insulation performance can be fully exhibited while maintaining the weight of the automotive sound insulation material. The lower limit of the average value of the acoustic impedance ratio (P / v) / Za is preferably 3 or greater, and more preferably 4 or greater. Furthermore, the upper limit of the average value of the acoustic impedance ratio (P / v) / Za is preferably 9 or less, and more preferably 8 or less.

[0057] The average value of the acoustic impedance ratio (P / v) / Za can be obtained by the following method. The acoustic impedance ratio (P / v) / Z0 between the air and the air at the surface opposite to the core layer of the air-impermeable resin film layer 40 provided on one surface of the core layer 10 is measured in a frequency range of 500 Hz to 6400 Hz. The acoustic impedance of air is represented by Z0. P / v is also called the acoustic impedance ratio (also called "specific acoustic impedance"). On the other hand, the acoustic impedance ratio Za / Z0 between the decoupling layer 30 at its surface and the air in a state without the core layer 10 and the air-impermeable resin film 40 is measured in a frequency range of 500 Hz to 6400 Hz. And, according to the following formula, (P / v) / Za can be obtained from the measured values ​​of (P / v) / Z0 and Za / Z0 at each frequency.

[0058] [Mathematical formula 1]

[0059]

[0060] The average value of the acoustic impedance ratio (P / v) / Za can be the arithmetic mean obtained by measuring at frequency intervals of at least 2 Hz within the frequency range of 500 Hz to 6400 Hz. Both (P / v) / Z0 and Za / Z0 can be measured using a method conforming to ISO 10534-2 (two-microphone transfer function method). For example, a commercially available impedance tube (Model 4206 manufactured by B&K) can be used for measurement.

[0061] The sound pressure P and the sound particle velocity v vary not only due to differences in the configuration of the air-impermeable resin film layer 40 (e.g., raw material, thickness, etc.), but also due to differences in the configuration of the core layer 10 on which the air-impermeable resin film layer 40 is provided (e.g., raw material, core arrangement, total core layer thickness, core spacing, core wall thickness, etc.), as well as the adhesive strength between the air-impermeable resin film layer 40 and the core layer 10. The upper limit of the average value of the acoustic impedance ratio (P / v) / Z0 between the air-impermeable resin film layer 40 provided on the core layer 10 and air, for example, in the frequency range of 500 Hz to 6400 Hz is preferably 15 or less, more preferably 12 or less, and even more preferably 10 or less, but is not limited to these. Furthermore, the lower limit of the average value of the acoustic impedance ratio (P / v) / Z0 is preferably 3 or more, more preferably 5 or more, but is not limited to these.

[0062] The acoustic impedance ratio Za / Z0 between the decoupling layer 30 and air varies depending on the configuration of the decoupling layer 30 (e.g., the type of raw material, basis weight, etc.). There are no particular limitations on this acoustic impedance ratio Za / Z0; for example, within the frequency range of 500 Hz to 6400 Hz, the upper limit of its average value is preferably 1.5 or less, more preferably 1.3 or less, and even more preferably 1.1 or less. Furthermore, there is no particular limitation on the lower limit of the average value of the acoustic impedance ratio Za / Z0, but it is preferably 1.0 or greater.

[0063] According to the first embodiment, an airtight resin film layer 40 is provided on at least one surface of the core layer 10 having an open end and a closed surface separated by a row, and a decoupling layer 30 is further provided on the outside thereof, and the above-mentioned acoustic impedance ratio (P / v) / Za is set within the above-mentioned numerical range. This not only makes it possible to achieve lightweighting of the automobile sound insulation material while ensuring high rigidity, but also makes it possible to exhibit sufficient sound insulation performance against noise with a frequency of 500 Hz to 6400 Hz generated in the automobile.

[0064] (Second embodiment)

[0065] like Figure 6 As shown, the automobile sound insulation material of the second embodiment includes: the core layer 10 described above; a first air-impermeable resin film layer 40a provided on one surface of the core layer 10; a decoupling layer 30 provided on the outer side thereof; and a second air-impermeable resin film layer 40b provided on the other surface of the core layer 10. The same components as those of the first embodiment are denoted by the same reference numerals (e.g., reference characters), and detailed descriptions thereof are omitted.

[0066] The first air-impermeable resin film layer 40a has the same configuration (resin film material, thickness, etc.) as the configuration already described for the first air-impermeable resin film layer 40. Furthermore, although the second air-impermeable resin film layer 40b does not yet have a further decoupling layer disposed on its outer surface, it preferably has the same performance as the first air-impermeable resin film layer 40a. Specifically, the average value of the acoustic impedance ratio, represented by the sound pressure P and acoustic particle velocity v on the surface of the second air-impermeable resin film layer 40b opposite the core layer 10, and the acoustic impedance Z2a on the surface of the sound-absorbing material when the core layer 10 is filled with the sound-absorbing material, is preferably 2.8 < (P / v) / Z2a < 10 between 500 Hz and 6400 Hz.

[0067] It should be noted that when the first and second air-impermeable resin film layers 40a and 40b are provided on both surfaces of the core layer 10 in this manner, the acoustic impedance ratio (P / v) / Z0 between the first air-impermeable resin film layer 40a and air is measured on the surface of the first resin film layer 40a opposite the core layer 10, without the decoupling layer 30. Furthermore, the acoustic impedance ratio (P2 / v2) / Z0 between the second air-impermeable resin film layer 40b and air is measured on the surface of the second air-impermeable resin film layer 40b opposite the core layer 10. The acoustic impedance ratio Za / Z0 between the decoupling layer 30 and air is measured, similar to the first embodiment, without the core layer 10 and the first air-impermeable resin film layer 40a. The acoustic impedance ratio Z2a / Z0 between the sound-absorbing material within the core layer 10 and air is measured without the second air-impermeable resin film layer 40b.

[0068] According to the second embodiment, even if first and second air-impermeable resin film layers 40a and 40b are provided on both surfaces of a core layer 10 separated by a row of open ends and closed surfaces, the second air-impermeable resin film layer 40b has the same properties as the first air-impermeable resin film layer 40a, thereby achieving the same effects as the first embodiment. Furthermore, by providing the second air-impermeable resin film layer 40b, the open ends 22 on at least one surface of the core layer 10 are blocked, thereby further increasing the sound transmission loss of the automotive sound insulation material.

[0069] (Third embodiment)

[0070] like Figure 7As shown, the automobile sound insulation material of the third embodiment includes: the core layer 10 described above; an airtight resin film layer 40 provided on one surface of the core layer 10; a decoupling layer 30 provided on the outer side thereof; and a resin film layer 50 having a plurality of openings on the surface of the core layer 10 opposite to the first airtight resin film layer 40. The same components as those of the first and second embodiments are denoted by the same reference numerals (e.g., reference characters), and detailed descriptions thereof are omitted.

[0071] The resin film layer 50 having a plurality of openings (hereinafter referred to as the opening film layer 50) has a plurality of holes 55 that penetrate the layer. The holes 55 are pre-punched before being attached to the core layer 10, for example, by a hot needle or punching process (punching process using a male die and a female die). To prevent the holes from being clogged, the hole shape is preferably one that minimizes burrs.

[0072] The aperture pattern of the apertures 55 is preferably arranged in a staggered or grid pattern, but is not particularly limited. The porosity of the apertured film layer 50 is preferably in the range of 0.2% to 5%, but is not particularly limited. The diameter of the apertures 55 is preferably in the range of 0.25 mm to 2.5 mm, and more preferably in the range of 0.3 mm to 2.0 mm.

[0073] In addition, the spacing between the holes 55 of the apertured film layer 50 is Figure 2 The spacing Pcx and Pcy of the cells 20 of the core layer 10 shown do not need to be consistent. Furthermore, when the apertured film layer 50 is attached to the core layer 10, it is not necessary to align the holes 55 with the cells 20. This is because by randomly overlapping the holes 55 of the apertured film layer 50 with the open ends 22 of the cells 20 of the core layer 10, proper internal and external connectivity can be ensured. The spacing of the holes 55 of the apertured film layer 50 is preferably smaller than the spacing of the cells 20 of the core layer 10 in at least one of the X and Y directions.

[0074] According to the third embodiment, even if an apertured film layer 50 is provided on the surface of the core layer 10 opposite the air-impermeable resin film layer 40, the same effects as those of the first embodiment can be achieved. Furthermore, the aperture pattern pre-formed in the apertured film layer 50 allows for easy adjustment and stable maintenance of the degree of closure of the open ends 22 on at least one surface of the core layer 10. This allows for control of the ratio of sound insulation to sound absorption in the automotive sound insulation material. This makes it easier to control the acoustic impedance ratio (P / v) / Za for the first air-impermeable resin film layer 40a and the decoupling layer 30, and thus makes it easier to control the sound insulation and sound absorption performance of the automotive sound insulation material.

[0075] (Fourth embodiment)

[0076] like Figure 8As shown, the automobile sound insulation material of the fourth embodiment includes: the core layer 10 described above; a plurality of airtight resin film layers 40a and 40b provided on one surface of the core layer 10; and a decoupling layer 30 provided outside the airtight resin film layer. The same components as those of the first and second embodiments are denoted by the same reference numerals (e.g., reference characters), and detailed descriptions thereof are omitted.

[0077] The multiple air-impermeable resin film layers 40a and 40b may have the same configuration (material, thickness, etc.) or different configurations. When the multiple air-impermeable resin film layers 40a and 40b are disposed between the core layer 10 and the decoupling layer 30 in this manner, the sound pressure P and the sound particle velocity v are measured on the surface of the outermost air-impermeable resin film layer 40b when the multiple air-impermeable resin film layers 40a and 40b are disposed on the core layer 10.

[0078] According to the fourth embodiment, even if a plurality of air-impermeable resin film layers 40a and 40b are provided between the core layer 10 and the decoupling layer 30, the same effects as those of the first embodiment can be achieved. Furthermore, by providing the plurality of air-impermeable resin film layers 40a and 40b with different configurations, the degree of design freedom in adjusting the acoustic impedance ratio (P / v) / Za can be increased, and the sound insulation performance of the automotive sound insulation material can be more easily controlled.

[0079] Example

[0080] Hereinafter, examples of the present invention and comparative examples are described.

[0081] As Example 1, a Figure 4 and Figure 5 The multi-layered sound insulation material for automobiles shown in FIG. Figures 1 to 3 A 50 μm thick airtight resin film (a three-layer film made of polyethylene / polyamide / polyethylene) was attached to one surface of the core layer (made of polypropylene resin, with a spacing Pcy between units of 4 mm and a core layer thickness of 6 mm) of the structure shown. The acoustic impedance ratio (P / v) / Z0 between the airtight resin film and air at its surface was measured using an impedance tube (model 4206, Φ29, manufactured by B&K) over a frequency range of 500 Hz to 6400 Hz. Next, a felt (made of mixed cotton, manufactured by needle punching, with a basis weight of 300 g / m2) was attached to the surface of the airtight resin film. 2) is pasted on the outside of the airtight resin film as a decoupling layer. In addition, the acoustic impedance ratio Za / Z0 between the surface of the felt and the air is measured using the above-mentioned impedance tube in the frequency range of 500 Hz to 6400 Hz. The acoustic impedance ratio (P / v) / Za is calculated based on these measured values. The average value of the acoustic impedance ratio (P / v) / Za of Example 1 is 7.7 in the frequency range of 500 Hz to 6400 Hz. In addition, the surface density of the automobile sound insulation material of Example 1 is 666 g / m 2 .

[0082] The same procedures as in Example 1 were followed to produce automotive sound insulation materials according to Examples 2 to 12, with the materials, basis weights, and thicknesses of the airtight resin film and decoupling layer varied, as shown in Table 1 below. The acoustic impedance ratios (P / v) / Z0 and Za / Z0, as well as the surface density, were measured. Furthermore, as a comparative example, the acoustic impedance ratio and surface density of a rubber sheet of the same size (raw material: ethylene propylene diene monomer (EPDM)) were measured. The results, including those of Example 1, are shown in Tables 1 and 2. Figure 9 middle.

[0083] [Table 1]

[0084]

[0085] As shown in Table 1 and Figure 9 As shown, it can be confirmed that: compared with the surface density of 1000g / m 2 In the comparative example of the rubber sheet, each embodiment can obtain a large acoustic impedance ratio relative to the surface density, and can also exhibit high sound insulation even when the automobile sound insulation material is lightweight. Figure 10 middle. Figure 10 The following table shows the results of sound transmission loss (dB) measurements for Example 1 and a comparative example at frequencies between 100 Hz and 5000 Hz. Sound transmission loss was measured using a combination of a reverberation chamber and an anechoic chamber to measure sound intensity. The relationship between sound transmission loss and each measured value is shown in the following equation. The measurement sample dimensions were 500 mm x 600 mm.

[0086] TL=SPL0-PWL i +10log 10 S-6

[0087] TL: Transmission loss (dB)

[0088] SPL0: Average sound pressure level in the reverberation room (dB)

[0089] PWL i : Power level of sound transmission (dB)

[0090] S: Sample area (m2 )

[0091] like Figure 10 As shown, in Example 1, the sound transmission loss in the frequency range of 500 Hz to 5000 Hz is about 3 dB higher with a mass of about two-thirds of that of the comparative example. This shows that even if the automobile sound insulation material is significantly reduced in weight, a high sound insulation effect can be maintained.

[0092] Industrial Applicability

[0093] The automotive sound insulation material of the present invention achieves sufficient sound insulation performance through the air-impermeable resin film and the decoupling layer while maintaining high rigidity while reducing weight. More specifically, the automotive sound insulation material of the present invention is useful for components such as carpets, floor mats, trunk trim, trunk floors, dash insulators, and undercovers that block noise from the vehicle interior and the source of noise.

[0094] Description of Reference Signs

[0095] 1: Core material

[0096] 10: Core layer

[0097] 11: Yamabe

[0098] 12: Tanibe

[0099] 13: Side face

[0100] 14: Bottom

[0101] 15: Mountain connection surface

[0102] 16: Valley connection surface

[0103] 17: Top

[0104] 18: Back side of core material

[0105] 19: Through hole

[0106] 20: Unit

[0107] 21: Closed surface

[0108] 22: Open end

[0109] 30: Decoupling layer

[0110] 40: Impermeable resin film layer

[0111] 50: Resin film layer with multiple openings

[0112] 55: Hole

Claims

1. A multi-layered automobile sound insulation material comprising a core layer, a first air-impermeable resin film layer, and a decoupling layer, wherein the core layer comprises cylindrical units arranged in multiple rows, the first air-impermeable resin film layer is disposed on at least one surface of the core layer, and the decoupling layer is disposed on a surface of the first air-impermeable resin film layer opposite to the core layer; Each of the cells of the core layer has a closed surface at one end and an open end at the other end, and the open ends of the cells are arranged in rows with adjacent cells interposed therebetween on both surfaces of the core layer. The first airtight resin film layer has no open holes, The closed surface of the unit of the core layer can ensure to become the bonding surface between the first airtight resin film layer and the core layer, The average value of the acoustic impedance ratio expressed by the sound pressure P and sound particle velocity v at the surface of the first airtight resin film layer arranged on the core layer on the opposite side of the core layer and the acoustic impedance Za of the decoupling layer is 2.8<(P / v) / Za<10 between 500Hz and 6400Hz.

2. The automobile sound insulating material according to claim 1, wherein The thickness of the first air-impermeable resin film layer is 50 μm to 200 μm.

3. The automobile sound insulating material according to claim 1 or 2, further comprising a resin film layer having a plurality of openings, wherein the resin film layer having a plurality of openings is bonded to a surface of the core layer opposite to a surface to which the first air-impermeable resin film layer is bonded.

4. The automobile sound insulating material according to claim 1 or 2, wherein: A pitch Pcy between the cells in the core layer in a direction of a row formed by adjacent cells is 10 mm or less.

5. The automobile sound insulating material according to claim 1 or 2, wherein: The first air-impermeable resin film layer has a structure formed by laminating a plurality of different materials.

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