sound-absorbing board

Abstract

To provide a sound absorbing board that can improve rigidity while presenting sound absorbency, as well as a package tray, a luggage board, and a sound insulation structure including the sound absorbing board.SOLUTION: A sound absorbing board 10 includes: a pair of skin materials 20 which contain a polyurethane foam 11 having an open-cell structure, which are integrated with front and rear surfaces of the polyurethane foam 11, respectively, and which have air permeability; and impregnated layers 22 which are included in the skin materials 20 and in which a raw material 11M of the polyurethane foam 11 is impregnated and cured. A ventilation volume of the skin materials 20 including the impregnated layers 22 based on JIS K6400-7 B method:2012 is 3 to 90 ml / cm2 / s.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure provides: sound-absorbing board Regarding. [Background technology]

[0002] Patent Document 1 describes a package tray that separates a vehicle interior from a luggage compartment as an example of a vehicle part that uses a board material. Package trays made of wood boards are known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-87855 (Paragraph

[0015] , Figure 1) Summary of the Invention [Problem to be solved by the invention]

[0004] tree On the quality board , suck There was a problem with the sound not being fully realized. 。 [Means for solving the problem]

[0005] A first aspect of the invention made to solve the above problems is a sound-absorbing board comprising a polyurethane foam having an open-cell structure, the board comprising a pair of breathable skin materials respectively integrated on the front and back surfaces of the polyurethane foam, and an impregnated layer included in the skin materials and impregnated with and cured by a raw material of the polyurethane foam, the air permeability of the skin material including the impregnated layer being 3 to 90 ml / cm according to JIS K6400-7 Method B:2012. 2 / s, a sound-absorbing board.

[0006] A second aspect of the invention is the sound-absorbing board according to the first aspect, wherein the skin material comprises one or more laminated fiber sheets.

[0007] A third aspect of the invention is the sound-absorbing board according to the first or second aspect, wherein the skin material is provided with a base sheet impregnated with the raw material of the polyurethane foam, and the impregnated layer further contains a resin that is adhered to at least a portion of the base sheet and different from the resin of the polyurethane foam.

[0008] A fourth aspect of the present invention is the sound-absorbing board according to any one of the first to third aspects, wherein the pair of skin materials on the front and back sides have the same configuration.

[0009] A fifth aspect of the invention is the sound-absorbing board according to any one of the first to fourth aspects, which has a reverberation chamber sound absorption coefficient based on JIS A1409:1998 of 0.4 or more.

[0010] A sixth aspect of the invention is a package tray arranged to separate the space behind the rear seat of a vehicle from the passenger compartment into upper and lower sections, and comprises a sound-absorbing board described in any one of the first to fifth aspects, and a fixing portion for fixing the sound-absorbing board in a spanning state between a pair of side walls of the vehicle that sandwich the space behind the rear seat in the vehicle width direction.

[0011] A seventh aspect of the invention is a luggage board in which the sound-absorbing board described in any one of the first to fifth aspects is superimposed on at least the upper surface of a sound-insulating panel material and is arranged in the luggage compartment of a vehicle.

[0012] An eighth aspect of the invention is a sound-insulating structure in which a sound-absorbing board according to any one of the first to fifth aspects is placed between a pair of sound-insulating panel materials.

[0013] A ninth aspect of the invention is the sound insulating structure according to the eighth aspect, wherein the sound absorbing board is in close contact with the pair of panel materials in a non-adhesive state. [Effects of the Invention]

[0014] In the sound-absorbing board according to the first aspect of the invention, skin materials are integrated with the front and back surfaces of polyurethane foam having an open-cell structure. The skin materials are provided with impregnated layers formed by impregnating and curing the raw materials of the polyurethane foam. This improves the rigidity of the sound-absorbing board. Moreover, since the skin materials are arranged on both the front and back surfaces of the polyurethane foam, the sound-absorbing board is less likely to warp than when the skin materials are arranged on only one side of the polyurethane foam. In addition, in this aspect, the air permeability of the skin material including the impregnated layers according to JIS K6400-7 B Method: 2012 is 3 to 90 ml / cm. 2 By setting the thickness to / s, breathability can be imparted to the entire sound-absorbing board, allowing the sound-absorbing properties of the polyurethane foam to be fully utilized.

[0015] According to the second aspect of the invention, the fiber sheet of the skin material is impregnated with the raw material of the polyurethane foam, so that an impregnated layer can be easily formed on the skin material.

[0016] In the third aspect of the invention, when the polyurethane foam is foam-molded integrally with the skin material, the resin adhered to the base sheet can prevent the raw material of the polyurethane foam from leaking out of the skin material.

[0017] In the fourth aspect of the invention, the surface materials on the front and back of the polyurethane foam have the same structure, so that it is possible to reduce warping of the sound-absorbing board.

[0018] In the fifth aspect of the invention, by setting the reverberation chamber sound absorption coefficient based on JIS A1409:1998 to 0.4 or more, it is possible to impart excellent sound absorption properties to the sound absorbing board.

[0019] As in the sixth aspect of the invention, if the sound-absorbing board is used in a package tray of a vehicle, it becomes possible to absorb sound from the passenger compartment and the luggage compartment while ensuring the rigidity of the package tray. When the sound-absorbing board is used in the package tray in this way, the package tray may be provided with fixing portions for fixing the sound-absorbing board across a pair of side walls that sandwich the space behind the rear seat in the vehicle width direction.

[0020] As in the seventh aspect of the invention, if a sound-absorbing board is laid on at least the upper surface of a sound-insulating panel material and used as a luggage board of a vehicle, it becomes possible to absorb sound from the luggage compartment side (vehicle interior side).If the sound-absorbing board is laid on the underside of the panel material as well, it becomes possible to absorb sound from the underside of the luggage board.

[0021] In the eighth and ninth aspects of the invention, a sound-absorbing board is placed between a pair of sound-insulating panel materials. When the pair of panel materials and the sound-absorbing board are in close contact with each other, the panel materials and the sound-absorbing board are left unbonded without being fixed with adhesive or pressure-sensitive adhesive, allowing the sound-absorbing board (particularly the surface material) to maintain its breathability (ninth aspect of the invention). This allows the sound-absorbing board to absorb sound transmitted through the panel materials, improving sound insulation (silence). [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a cross-sectional side view of a sound-absorbing board according to an embodiment of the present disclosure; [Figure 2] (A) A cross-sectional side view of the mold in an open state and the skin material fixed to the mold. (B) A cross-sectional side view of the mold and the skin material when the mold is open and raw material is being injected. [Figure 3] (A) Side cross-sectional view of the mold and skin material when the mold is closed and the raw material begins to foam, (B) Side cross-sectional view of the polyurethane foam and skin material foamed inside the mold [Figure 4] Table showing an example [Figure 5] Table showing comparative examples [Figure 6] (A) A perspective view of a package tray positioned at the rear of a vehicle. (B) A cross-sectional view of a package tray secured to the side wall of a vehicle. [Figure 7] (A) A perspective view of a luggage board placed on a vehicle, (B) a cross-sectional view of a luggage board placed on a vehicle. [Figure 8] Side cross-section of a building's double wall and sound-absorbing board [Figure 9]10 is a side view of a sound-absorbing board manufacturing line according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] As shown in FIG. 1, the sound-absorbing board 10 is made up of polyurethane foam 11 having an open-cell structure and skin materials 20 integrated on both the front and back sides.

[0024] The polyurethane foam 11 may be made of a flexible polyurethane foam, a rigid polyurethane foam, or a semi-rigid polyurethane foam. Flexible polyurethane foams are soft and have low rigidity, while rigid polyurethane foams are hard and too rigid. Semi-rigid polyurethane foams, which have appropriate rigidity, are more preferred. The apparent density of the polyurethane foam 11 (based on JIS K7222:2005) is 30 to 250 kg / m 3 It is preferable that the density is 40 to 100 kg / m 3 The thickness of the polyurethane foam 11 is preferably 2 to 70 mm, more preferably 3 to 50 mm.

[0025] The air permeability of the polyurethane foam 11 is measured in accordance with JIS K6400-7 B Method: 2012 with the surface materials 20 removed from both the front and back sides of the sound-absorbing board 10 (without a skin layer). The air permeability of the polyurethane foam 11 at a thickness of 10 mm is 5 to 250 ml / cm. 2 / s, and 10 to 250 ml / cm 2 / s. When the thickness of the polyurethane foam 11 is less than 10 mm, the value of the air permeability is converted to a value corresponding to a thickness of 10 mm. Specifically, the thickness is represented by X (mm), and the measured value of the air permeability is represented by Y (ml / cm). 2 / s), the conversion value (ml / cm 2 / s) is calculated as the converted value = Y × X / 10.

[0026] The covering material 20 comprises a breathable base sheet, and an impregnated layer 22 is formed on the base sheet by impregnating and curing a raw material 11M of the polyurethane foam 11. Specifically, in this embodiment, the base sheet is made of a fiber sheet 21, and the impregnated layer 22 is formed on the surface of the fiber sheet 21 that comes into contact with the polyurethane foam 11, on both sides of the covering material 20 on the front and back of the polyurethane foam 11. The air permeability of the covering material 20 including the impregnated layer 22 based on JIS K6400-7 Method B:2012 is 3 to 90 ml / cm. 2 / s, and 5 to 80 ml / cm 2 / s is more preferable.

[0027] Examples of fibers that may be used to form the fiber sheet 21 include polyethylene terephthalate (PET) fibers, polyester fibers, polypropylene fibers, polyamide fibers, acrylic fibers, vinylon fibers, polyurethane fibers (spandex), glass fibers, carbon fibers, natural fibers (e.g., wool, cotton, cellulose nanofibers, etc.), and Zylon (registered trademark). Examples of the form of the fiber sheet 21 include nonwoven fabrics, woven fabrics, knitted fabrics, etc. Examples of nonwoven fabrics include spunlace nonwoven fabrics, spunbond nonwoven fabrics, and needle-punched nonwoven fabrics.

[0028] The fiber diameter of the fiber sheet 21 is preferably 2 to 10 denier (d), more preferably 2 to 8 denier. The basis weight of the fiber sheet 21 is 70 to 500 g / m 2 It is preferable that the density is 90 to 500 g / m 2 When the fiber sheet 21 is made of fibers having a small fiber diameter in this manner, the distance between the fine fibers can be shortened to make the fibers dense, which makes it difficult for the raw material 11M of the polyurethane foam 11 to seep out of the fiber sheet 21 (skin material 20).

[0029] The fiber sheet 21 (base sheet) further contains 35 to 100 g / m of a resin different from the resin of the polyurethane foam 11 (a polyurethane resin obtained by impregnating and curing the raw material 11M).2 It is preferable that the resin be adhered to the fiber sheet 21. Examples of the resin include non-polyurethane resins, such as acrylic ester resins (e.g., ethyl acrylate) and rubber resins (e.g., styrene-butadiene rubber (SBR)). The resin adhered to the fiber sheet 21 allows the resin to intervene between the fibers. This makes it difficult for the raw material 11M of the polyurethane foam 11 to pass through the fiber sheet 21 (skin material 20) when the polyurethane foam 11 is integrally foam-molded with the skin material 20, thereby further reducing the exudation of the raw material 11M. The resin may be adhered to the surface of the fiber sheet 21 or to the fibers inside the fiber sheet 21. For example, in the latter case, the polyurethane resin constituting the impregnation layer 22 may cover the resin adhered to the fibers. In addition, the adhesive resin can be attached to the fiber sheet 21 by applying an emulsion to the surface of the fiber sheet 21, impregnating the fiber sheet 21 with the emulsion, or scattering powder on the surface of the fiber sheet 21 and applying a heated roller or hot air thereto.

[0030] The air permeability of the impregnated layer 22 of the skin material 20 can be adjusted by adjusting the type of fiber constituting the fiber sheet 21, the fiber diameter, the basis weight, the amount of the attached resin such as an acrylic ester resin, etc. This allows the entire sound-absorbing board 10 to have air permeability, and provides the sound-absorbing board 10 with sound-absorbing properties.

[0031] In the skin material 20 of this embodiment, the inner fiber sheet 21A arranged on the polyurethane foam 11 side of each skin material 20 has a fiber diameter of 3 denier and a basis weight of 100 g / m 2 The PET fiber contains 50g / m of acrylic ester resin as a resin other than polyurethane resin. 2 The outer fiber sheet 21B, which is impregnated with the inner fiber sheet 21A and is disposed on the outside of the inner fiber sheet 21A, has a fiber diameter of 6 denier and a basis weight of 150 g / m 2The inner fiber sheet 21A is made of PET fiber, and an impregnated layer 22 is formed by impregnating the inner fiber sheet 21A with the raw material 11M of the polyurethane foam 11, and the impregnated layer 22 has approximately the same thickness as the inner fiber sheet 21A. The inner fiber sheet 21A and the outer fiber sheet 21B are integrated by needle punching.

[0032] The inner fiber sheet 21A is made of densely packed fine fibers and is impregnated with an acrylic ester resin, which limits the amount of impregnation (seep) of the raw material 11M. This allows the impregnated layer 22 formed in the area in contact with the polyurethane foam 11 to be thin (reduced impregnation amount) or have a sparse distribution (uneven impregnation amount), thereby ensuring the breathability of the covering material 20. On the other hand, the outer fiber sheet 21B has a larger fiber diameter than the inner fiber sheet 21A, for example, 5 denier or more, which improves the abrasion resistance of the sound-absorbing board 10. In FIG. 1, the impregnated layer 22 is shown in gray.

[0033] Next, a method for manufacturing the sound-absorbing board 10 will be described. To manufacture the sound-absorbing board 10, first, a raw material 11M for the polyurethane foam 11 (see FIG. 2(B)) and a pair of skin materials 20 are prepared. Specifically, the raw material 11M for the polyurethane foam 11 contains a polyol component, a polyisocyanate component, a blowing agent, a catalyst, etc., and each skin material 20 (fiber sheets 21A, 21B integrated by needle punching) is prepared. Details of the raw material 11M for the polyurethane foam 11 are as follows:

[0034] The polyol component may be any of the ether polyols, ester polyols, ether ester polyols, polymer polyols, and the like known for use in the production of polyurethane foams, used alone or in combination. Examples of ether polyols include polyhydric alcohols such as ethylene glycol, propylene glycol, glycerin, and trimethylolpropane, as well as polyether polyols obtained by adding alkylene oxides such as ethylene oxide and propylene oxide to such polyhydric alcohols. Examples of ester polyols include polyester polyols obtained by polycondensation of aliphatic carboxylic acids such as malonic acid, succinic acid, and adipic acid, or aromatic carboxylic acids such as phthalic acid, with aliphatic glycols such as ethylene glycol, diethylene glycol, and propylene glycol. Furthermore, ether ester polyols containing both ether and ester groups in the polyol, and polymer polyols obtained by polymerizing an ethylenically unsaturated compound in an ether polyol, may also be used.

[0035] The polyisocyanate component may be any of aromatic, alicyclic, and aliphatic isocyanates, and may be a bifunctional isocyanate having two isocyanate groups in one molecule, a trifunctional or higher isocyanate having three or more isocyanate groups in one molecule, or a modified product thereof (for example, a urethane-modified, allophanate-modified, biuret-modified, or other modified product), and these may be used alone or in combination. Examples of difunctional isocyanates include aromatic isocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,4'-diphenylmethane diisocyanate, and 2,2'-diphenylmethane diisocyanate, alicyclic isocyanates such as cyclohexane-1,4-diisocyanate and isophorone diisocyanate, and aliphatic isocyanates such as butane-1,4-diisocyanate, hexamethylene diisocyanate, and lysine isocyanate. Examples of trifunctional or higher isocyanates include 1-methylbenzene-2,4,6-triisocyanate, 1,3,5-trimethylbenzene-2,4,6-triisocyanate, and polymeric MDI (polymethylene polyphenyl polyisocyanate).

[0036] The blowing agent is not particularly limited, but water is preferred. Further, carbon dioxide gas, pentane, hydrofluoroolefin (HFO), etc. may be used as a blowing assistant in combination with water as the blowing agent.

[0037] The catalyst may be any known catalyst used in the production of polyurethane foams. Examples include amine catalysts such as diethanolamine, triethylenediamine, bis(2-dimethylaminoethyl)ether, N,N,N',N",N"-pentamethyldiethylenetriamine, tetramethylguanidine, and imidazole-based compounds; tin catalysts such as stannous octoate; and metal catalysts (also called organometallic catalysts) such as phenylmercury propionate and lead octenate. A combination of catalysts may also be used.

[0038] A foam stabilizer may be included in raw material 11M of polyurethane foam 11. As the foam stabilizer, a known foam stabilizer used in the production of polyurethane foam can be used, such as a silicone-based foam stabilizer or a non-silicone-based surfactant.

[0039] The raw material 11M of the polyurethane foam 11 is prepared in two parts: Liquid A, which is a mixture of a polyol component, a blowing agent, a catalyst, etc., and Liquid B, which contains a polyisocyanate component. If the raw material 11M contains a foam stabilizer, this is mixed into Liquid A.

[0040] 2(A) shows a molding die 50 for molding the sound-absorbing board 10. The molding die 50 is composed of a lower die 51 and an upper die 52, and is pre-temperature-controlled to, for example, 70°C. A pair of skin materials 20 are fixed to a molding recess 51U provided in the lower die 51 and an opposing portion 52M of the upper die 52, which forms a cavity between the molding recess 51U and the upper die 52. At this time, the pair of skin materials 20 are arranged so that the fiber sheets 21 that will become the inner fiber sheets 21A face each other across the cavity. In this embodiment, only the inner fiber sheet 21A is impregnated with an acrylic ester resin.

[0041] Next, as shown in Fig. 2(B), raw material 11M, which is a mixture of liquids A and B, is poured into molding recess 51U of lower mold 51, and then mold 50 is closed (see Fig. 3(A)), and raw material 11M reacts and hardens to form polyurethane foam 11 (see Fig. 3(B)). At this time, raw material 11M impregnates a pair of skin materials 20 (more specifically, inner fiber sheets 21A) and hardens to form impregnated layer 22, and polyurethane foam 11 and skin materials 20 are bonded and integrated together.

[0042] When the mold 50 is opened and the integrated polyurethane foam 11 and skin material 20 are removed from the mold 50, the sound-absorbing board 10 shown in FIG. 1 is completed.

[0043] In the sound-absorbing board 10 of this embodiment, an open-cell polyurethane foam 11 is foam-molded integrally with a skin material 20. The skin material 20 is formed with an impregnation layer 22 impregnated with the polyurethane foam raw material 11M that constitutes the polyurethane foam 11, thereby increasing the rigidity of the skin material 20. This further improves the rigidity of the sound-absorbing board 10. In a sound-absorbing board in which the skin material 20 is disposed on only one side of the polyurethane foam 11, the skin material 20 (impregnation layer 22) and the polyurethane foam 11 have different shrinkage rates after the raw material 11M is foamed and cured, making the sound-absorbing board more susceptible to warping. In contrast, in the sound-absorbing board 10 of this embodiment, skin materials 20 with the same configuration are disposed on both the front and back of the polyurethane foam 11. This ensures that the shrinkage rates of the raw material 11M after foaming and curing are the same on both sides, making the sound-absorbing board 10 less susceptible to warping. Here, the skin materials 20 having the same configuration have substantially the same shape, material, and basis weight, and in this embodiment, the form of the fiber sheet 21 (nonwoven fabric, woven fabric, knitted fabric, etc.) is also the same, and the fiber diameter of the fiber sheet 21 and the impregnation amount of the acrylic ester resin as the adhesion resin are also substantially the same.

[0044] In the sound-absorbing board 10 of this embodiment, the polyurethane foam 11 has an open-cell structure and therefore has sound-absorbing properties. If the covering material 20 is breathable, sound generated outside the sound-absorbing board 10 passes through the covering material 20 and enters the interior of the polyurethane foam 11, allowing the polyurethane foam 11 to exhibit sound-absorbing properties. However, when the covering material 20 is impregnated with resin, it is generally difficult to make the covering material 20 breathable.

[0045] In response to this, the inventors of the present application discovered that it is possible to adjust the breathability of the impregnated layer 22 of the skin material 20 by adjusting the number of cells (air bubbles) per unit length of the polyurethane foam 11 and the amount of cell membranes, for example, by changing the composition of the raw material 11M of the polyurethane foam 11, and have thus completed the sound-absorbing board 10.

[0046] Furthermore, in this embodiment, since the skin material 20 is made of fiber sheet 21, when the raw material 11M of polyurethane foam 11 is impregnated, it is conceivable that the raw material 11M is likely to leak out of the skin material 20 to the outside of the sound-absorbing board 10. In contrast, in this embodiment, by densely packing thin fibers with a fiber diameter of 2 to 4 denier in each skin material 20 (specifically, the inner fiber sheet 21A of each skin material 20) and by impregnating with an acrylic ester resin, it is possible to prevent the raw material 11M of polyurethane foam 11 from leaking out of the skin material 20.

[0047] In manufacturing the sound-absorbing board 10, when preparing the skin material 20, the inner fiber sheet 21A of the fiber sheets 21, 21 may be impregnated in advance with, for example, an acrylic ester resin. [Example]

[0048] The above-described embodiment will be described in more detail below with reference to examples and comparative examples, but the sound-absorbing board of the present disclosure is not limited to the following examples.

[0049] 1. Ingredients and composition <Examples 1 to 6> In Examples 1 to 6, as in the manufacturing method described above, raw material 11M, which was a mixture of liquid A and liquid B, was reacted to foam-mold polyurethane foam 11 integrally with skin material 20, and test pieces of sound-absorbing boards measuring 500 mm x 500 mm x 20 mm (thickness) were produced in which skin material 20 was integrated on both the front and back sides of polyurethane foam 11.

[0050] In Examples 1 to 6, a pair of skin materials 20 (first skin material, second skin material) had the same structure, specifically, they were made of fiber sheets 21, 21 (an inner fiber sheet 21A and an outer fiber sheet 21B). The inner fiber sheet 21A was made of PET fiber with a fiber diameter of 3 denier and a basis weight of 100 g / m 2 The outer fiber sheet 21B is made of PET fiber with a fiber diameter of 6 denier and a basis weight of 150 g / m 2In the skin material 20 of this embodiment, only the inner fiber sheet 21A is impregnated with the acrylic ester resin, and the amount of impregnation is 50 g / m 2 It is as follows.

[0051] Examples 1 to 6 differed from one another only in the raw material 11M of the polyurethane foam 11. The composition and blending ratio of the raw material 11M are as shown in Figure 4. Details of the components contained in the raw material 11M are as follows.

[0052] (1)A liquid Polyol 1: Polyether polyol (number average molecular weight: 5000, number of functional groups: 3.6, hydroxyl value: 31.5 mg KOH / g) Polyol 2: Polymer polyol (number average molecular weight: 5000, number of functional groups: 3, hydroxyl value: 25 mg KOH / g, solid content: 30%) Foaming agent; water Amine catalyst 1: "Diethanolamine" manufactured by Showa Chemical Co., Ltd. Amine catalyst 2: Evonik Japan Co., Ltd., "DABCO BL-11" Foam stabilizer: Evonik Japan Co., Ltd., "TEGOSTAB B 8715 LF2" Additive: Polyether polyol (number average molecular weight: 5000, number of functional groups: 3, hydroxyl value 34 mg KOH / g) (2)B liquid Polyisocyanate 1: Polymeric MDI (NCO value 31.5%) Polyisocyanate 2: MDI modified product (weight ratio of 4,4'-MDI to urethane modified product (urethane prepolymer) of 4,4'-MDI is 75-85:15-25, NCO value: 26.5%)

[0053] 4 and 5, the blending ratio of polyisocyanate refers to the weight ratio of polyisocyanate 1 to polyisocyanate 2 in component B, with the number on the left indicating the proportion of polyisocyanate 1 and the number on the right indicating the proportion of polyisocyanate 2. The index in FIGS. 4 and 5 refers to the isocyanate index, which is the value obtained by dividing the number of moles of isocyanate groups in polyisocyanate by the number of moles of all active hydrogen groups in polyol, blowing agent (water), etc., and multiplying the result by 100.

[0054] The composition and blending ratio of the raw material 11M in Comparative Examples 1 to 4 are as shown in FIG. <Comparative Example 1> In Comparative Example 1, the covering material 20 is the same as the fiber sheets 21, 21 in Examples 1 to 6, and a fabric having a basis weight of 25 g / m 2 The non-breathable film and the inner fiber sheet 21A are laminated with an acrylic adhesive. Other than that, the comparative example is the same as in Example 2. In the comparative example 1, the non-breathable film prevents the raw material 11M of the polyurethane foam 11 from impregnating the skin material 20, and therefore the impregnated layer 22 is not formed on the skin material 20.

[0055] <Comparative Example 2> Comparative Example 2 is the same as Example 2 except that only the first skin (front side) of the pair of skins 20 is provided, and the second skin (rear side) is not provided.

[0056] <Comparative Examples 3 and 4> In Comparative Examples 3 and 4, raw material 11 of polyurethane foam 11 is different from Examples 1 to 6, but skin material 20 is the same (see FIG. 5).

[0057] <Comparative Example 5> A wooden board was prepared as Comparative Example 5. The thickness of this wooden board was 5 mm and the weight per unit area was 3500 g / m 2 (Density is 700 kg / m 3 ) The air permeability of wood boards cannot be measured using JIS K6400-7 B Method:2012, but they are non-breathable.

[0058] 2. Evaluation For each example and comparative example, the number of cells, apparent density, air permeability, sound absorption coefficient, hardness, bending strength, and warpage were evaluated. These measurement methods were as follows.

[0059] <Measurement method> (1) Number of cells The number of cells (air bubbles) per unit length (25 mm) was counted on the outer peripheral surface of polyurethane foam 11, and the resulting value was taken as the cell number. Specifically, a scanning electron microscope (SEM: manufactured by JEOL Ltd.) was used to take an enlarged image of the outer peripheral surface of polyurethane foam 11, and a line of unit length (25 mm) was drawn on the enlarged image. The number of cells where the line intersected was counted to obtain the cell number.

[0060] (2) Apparent density The apparent density of the polyurethane foam 11 was measured in accordance with JIS K7222:2005. Specifically, a test piece measuring 500 mm × 500 mm × 20 mm (thickness) was cut to 100 mm × 100 mm × 20 mm (thickness), the skin material 20 (including the impregnated layer 22, if present) was removed, and the apparent density of the remaining polyurethane foam 11 was measured. However, in Comparative Example 2, since only the first skin material (front side) was provided as the skin material 20, the first skin material was peeled off and the apparent density of the remaining polyurethane foam 11 was measured. The apparent density of the wood board of Comparative Example 5 was also measured.

[0061] (3) Ventilation volume The air permeability of the skin material 20 and the polyurethane foam 11 was measured according to JIS K6400-7 Method B:2012. Specifically, for Examples 1 to 6 and Comparative Examples 1 to 4, a test piece measuring 500 mm × 500 mm × 20 mm (thickness) was cut to a size of 100 mm × 100 mm × 20 mm (thickness). For each cut sample, the skin material 20 including the impregnation layer 22 was peeled off from the polyurethane foam 11 to separate it. The air permeability of the skin material 20 (front and back) was measured, and the air permeability of the polyurethane foam 11 from which the skin material 20 had been peeled off was also measured. In this case, if the polyurethane foam 11 was attached to the skin material 20 (specifically, the inner fiber sheet 21A), as much of the polyurethane foam 11 as possible was scraped off so as not to damage the fiber sheet 21, leaving only the skin material 20. The skin material 20 was measured with the inner fiber sheet 21A (impregnated layer 22) placed on the bottom (air was ventilated from bottom to top during the measurement). This is because if the outer fiber sheet 21B was placed on the bottom, air would leak from the sides of the outer fiber sheet 21B, making it impossible to accurately measure the amount of air permeation.

[0062] (4) Hardness The hardness of the sound-absorbing board test pieces was measured according to JIS K6400-2, Method E:2012. Specifically, for Examples 1 to 6 and Comparative Examples 1 to 4, test pieces measuring 500 mm × 500 mm × 20 mm (thickness) were cut to 200 mm × 200 mm × 20 mm (thickness), and placed with the first skin (front side) or the second skin (rear side) facing up. The test pieces were compressed from above at a compression speed of 50 mm / min using a compression jig (the pressing surface was circular with a diameter of 80 mm) until the deformation in the thickness direction was 80% of the original thickness of the test pieces. The load at 50% compression was recorded as the measured value. The test pieces were compressed from the first skin side (front side) and the second skin side (rear side), respectively, and the ratio of the measured loads (front side / rear side ratio) was calculated using the following formula: Back / Front Ratio = Back Measurement / Front Measurement x 100 In Comparative Example 2, only the first skin material on the front side was provided as the skin material 20, and only polyurethane foam 11 was provided on the back side of the first skin material, but measurements were taken under the same conditions when compressing from the polyurethane foam 11 side as when compressing from the first skin material side. Note that "front side" and "back side" in Figures 4 and 5 indicate whether the compression jig was applied to the front or back of the test piece.

[0063] (5) Bending strength The bending strength of the sound-absorbing board test pieces was measured based on JIS K7221-2:2006. Specifically, for Example 2 and Comparative Example 2, test pieces measuring 500 mm × 500 mm × 20 mm (thickness) were cut to 350 mm × 80 mm × 20 mm (thickness) and placed on a pair of cylindrical end supports with a radius of 15 mm (with a distance of 300 mm between the supports). Then, the test pieces were compressed from above at a compression speed of 100 mm / min so that a cylindrical end pressure wedge with a radius of 15 mm struck the center of the distance between the supports of each of the skin materials placed facing upward. The loads at which the test pieces were displaced (deflected) by 2 mm and 4 mm were measured. The bending strength was calculated using the following formula: R=1.5×Fr×(L / (b×d 2 ))×10 6 where R is the bending strength [N / cm 2 ], Fr is the load [kN] when the displacement is 2 mm or 4 mm, L is the distance between supports [mm], b is the width [mm] of the test piece, and d is the thickness [mm] of the test piece. Measurements were performed both when the first skin (front side) was on top and when the second skin (rear side) was on top. In Comparative Example 2, only the first skin was provided as the skin 20, and only polyurethane foam 11 was provided on the rear side of the first skin. However, even when the polyurethane foam 11 was on top, measurements were performed under the same conditions as when the first skin was on top. In Figures 4 and 5, "front side" and "rear side" indicate whether the cylindrical end pressure wedge was applied to the front or back of the test piece.

[0064] (6) Sound absorption coefficient The reverberation chamber sound absorption coefficient of test pieces of sound-absorbing boards was measured based on JIS A1409:1998. Specifically, in Examples 1 to 6 and Comparative Examples 1 to 4, test pieces measuring 500 mm × 500 mm × 20 mm (thickness) were used, and in Comparative Example 5, four wooden boards measuring 500 mm × 500 mm × 5 mm (thickness) were used. These were laid out on the floor of a reverberation chamber to form measurement samples measuring 1 m × 1 m × each thickness, and the reverberation chamber sound absorption coefficient was measured at each frequency. During this measurement, the outer periphery of the measurement sample was covered with an aluminum fixture, and the gaps between the test pieces and between the fixture were sealed with aluminum tape. The average sound absorption coefficient obtained by averaging the measured sound absorption coefficients at each frequency (500 Hz, 630 Hz, 800 Hz, 1000 Hz, 1250 Hz, 1600 Hz, 2000 Hz, 2500 Hz, 3150 Hz, 4000 Hz, 5000 Hz, 6300 Hz) was taken as the reverberation chamber sound absorption coefficient. The measurement sample for Comparative Example 2 was placed with the first skin material on top and the surface opposite the first skin material fixed to the floor of the reverberation chamber with double-sided tape, and measurement was performed. This is because the test piece for Comparative Example 2 was warped, and if a space was created between it and the floor, accurate measurement would not be possible.

[0065] (7) Warping In Examples 1 to 6 and Comparative Examples 1 to 4, test pieces measuring 500 mm × 500 mm × 20 mm (thickness), and in Comparative Example 5, a wooden board measuring 500 mm × 500 mm × 5 mm (thickness), were placed on a horizontal surface and visually inspected for warping. Specifically, gaps between the outer edges of each test piece and wooden board and the horizontal surface were inspected both with the first skin (front side) of each test piece and wooden board facing up and with the second skin (rear side) facing up. The presence or absence of warping was evaluated as "present" if a gap was observed in at least one of the orientations, and as "absent" if no gap was observed in either orientation.

[0066] <Evaluation results> 4 and 5 include test pieces in which an impregnation layer 22 is formed on the skin material 20 (Examples 1 to 6 and Comparative Examples 2 to 4), and test pieces in which an impregnation layer 22 is not formed on the skin material 20 (Comparative Example 1). For the former test pieces provided with the impregnation layer 22, it was confirmed that the configurations in which the skin material 20 is integrated with both the front and back surfaces of the polyurethane foam 11 (Examples 1 to 6 and Comparative Examples 3 and 4) reduced warping of the test pieces compared to the configuration in which the skin material 20 is integrated with only one of the front and back surfaces of the polyurethane foam 11 (Comparative Example 2). Comparative Example 1, in which the impregnation layer 22 is not provided, showed no warping. This is thought to be because the non-breathable film prevented the skin material 20 from being impregnated with the raw material 11M, and therefore the skin material 20 itself was not affected by shrinkage due to the foaming and curing of the raw material 11M. The thickness of the impregnated layer 22 formed on the skin material 20 of Examples 1 to 6 and Comparative Examples 2 to 4 was approximately the same as the thickness of the inner fiber sheet 21A.

[0067] Next, focusing on the air permeability of the skin material 20, it was confirmed that the blending of the raw material 11M of the polyurethane foam 11 in Examples 1 to 6 and Comparative Examples 2 to 4 made the skin material 20 having the impregnated layer 22 breathable.

[0068] A comparison of Examples 1 to 6 and Comparative Examples 2 and 4 with Comparative Example 1 reveals that the test pieces in which the covering material 20 is breathable have a higher reverberation chamber sound absorption coefficient than the test piece in which the covering material 20 is not breathable (Comparative Example 1). This is thought to be because, in the test pieces of Examples 1 to 6 and Comparative Examples 2 and 4, the incident sound passes through the covering material 20 and reaches the polyurethane foam 11, and the polyurethane foam 11 exhibits sound absorption properties, whereas in Comparative Example 1, the non-breathable film of the covering material 20 prevents the incident sound from reaching the polyurethane foam 11, and the polyurethane foam 11 does not exhibit sound absorption properties. In Comparative Example 1, the sound absorption properties are thought to be mainly exhibited by the covering material 20 (more specifically, the fiber sheets 21, 21 laminated from the outside to the non-breathable film). Furthermore, the air permeability of the covering material 20 (first covering material) was 3 ml / cm. 2In Comparative Example 3, where the sound absorption coefficient was less than / s, the reverberation chamber sound absorption coefficient was as low as in Comparative Example 1, where the skin material 20 had no breathability, and it was found that the breathability of the skin material 20 was insufficient to allow the polyurethane foam 11 to exhibit its sound absorption properties. Note that the test pieces of Examples 1 to 6 and Comparative Examples 1 to 4 had higher sound absorption coefficients in the reverberation chamber than the wood board of Comparative Example 5.

[0069] The ventilation rate of the skin material 20 is 90 ml / cm 2 In Comparative Example 4, where the reverberation chamber sound absorption coefficient exceeded 1 / s, the reverberation chamber sound absorption coefficient was lower than in Examples 1 to 6. This is thought to be because the air permeability of the skin material 20 and the polyurethane foam 11 became too high, which reduced the sound absorption of the test piece, and also because molding of the polyurethane foam 11 became difficult, making it impossible to produce a good test piece.

[0070] Focusing on the hardness of the test pieces of Examples 1 to 6 and Comparative Examples 1 to 4, in Examples 1 to 6, Comparative Example 1, and Comparative Examples 3 and 4, skin materials were provided on both the front and back sides of the test pieces, and the measured hardness values ​​on the front and back sides were approximately equal, with a back / front ratio of 101 to 102%. In contrast, in Comparative Example 2, only the first skin material was provided on the front side as the skin material 20, and only polyurethane foam 11 was provided on the back side of the first skin material, resulting in a large difference in hardness measurements between the front and back sides of the sound-absorbing board, with a back / front ratio of 68%. This indicates that the characteristics of the front and back sides of the sound-absorbing board differ significantly. The back / front ratio is preferably 70% to 143%, more preferably 85% to 118%, and even more preferably 95% to 105%. The closer the back / front ratio is to 100%, the more the difference in hardness (rigidity) between the first skin material (front side) and the second skin material (back side) can be eliminated. Comparing Example 2 with Comparative Example 1, Example 2 has impregnated layers 22 on both the front and back skin materials 20, while Comparative Example 1 does not have the impregnated layer 22 formed by a non-breathable film. The hardness of Example 2 and Comparative Example 1 is equivalent, and it can be said that the impregnated layer 22 has the same level of hardness as a non-breathable film.

[0071] Looking at the bending strength of the test pieces of the sound-absorbing boards of Example 2 and Comparative Example 2, Example 2, in which skin material 20 having impregnated layers 22 is provided on both the front and back sides of polyurethane foam 11, has a much greater bending strength than Comparative Example 2, in which skin material 20 is provided on only one side of polyurethane foam 11. When the displacement of the test piece is 2 mm, the load when pressure is applied from the front side in Example 2 is 5.78 N / cm 2 In Example 2, the load when pressure was applied from the back side was 5.44 N / cm 2 In Comparative Example 2, the load when pressure was applied from the front side (first skin side) was 0.06 N / cm 2 In Comparative Example 2, the load when pressure was applied from the back side (polyurethane foam side) was 1.87 N / cm 2 Similarly, when the displacement of the test piece is 4 mm, the load when pressure is applied from the front side in Example 2 is 17.87 N / cm 2 In Example 2, the load when pressure was applied from the back side was 17.09 N / cm 2 In Comparative Example 2, the load when pressure was applied from the front side (first skin side) was 0.85 N / cm 2 In Comparative Example 2, the load when pressure was applied from the back side (polyurethane foam side) was 4.13 N / cm 2 Compared to the test piece of Example 2, the test piece of Comparative Example 2 is displaced greatly with a small load, and can be said to have low rigidity. In Comparative Example 2, the bending strength of the first skin material (front side) is greater than that of the opposite side (rear side) of the first skin material, but compared to Example 2, the measured values ​​are about 1 / 3 when the displacement is 2 mm, and about 1 / 4 when the displacement is 4 mm.

[0072] Furthermore, when we look at the warpage of the test pieces of Examples 1 to 6 and Comparative Example 2, when the first skin material was placed facing upward in Comparative Example 2, the gap between the horizontal surface and the center of the sound-absorbing board was extremely large at approximately 19 mm. This is thought to be because the skin material (impregnated layer) and the polyurethane foam have different shrinkage rates after the raw materials are foamed and cured, resulting in significant warpage toward the skin material.

[0073] From the above results, it is found that the air permeability of the skin material 20 including the impregnated layer 22 is 3 to 90 ml / cm 2 It was found that in Examples 1 to 6 where the sound absorption coefficient was / s, test pieces (sound absorbing boards 10) with good sound absorption properties could be easily obtained.

[0074] [Example of using sound-absorbing board] The following describes an example of how the sound-absorbing board 10 is used. Figures 6(A) and 6(B) show an example in which the sound-absorbing board 10 is provided on a package tray 70 for a vehicle 60.

[0075] The package tray 70 is provided, for example, behind the rear seat 61 of a hatchback-type vehicle 60. The package tray 70 spans a pair of side walls 62 (e.g., deck side trim) that sandwich a luggage compartment 60N behind the rear seat 61 of the vehicle 60 in the vehicle width direction, and separates the luggage compartment 60N from the passenger compartment 60R into upper and lower compartments. More specifically, the package tray 70 is supported from below by support protrusions 63 that protrude inward from the pair of side walls 62. In this example, a plurality of support protrusions 63 are provided lined up in the front-to-rear direction of the vehicle.

[0076] As shown in the enlarged view of FIG. 6A , the package tray 70 is provided with a fixing portion 71 for fixing the sound-absorbing board 10 to the support protrusions 63 (in this example, the rearmost support protrusion 63) of the sidewall 62. The fixing portion 71 is attached to the outer periphery of the sound-absorbing board 10. More specifically, the fixing portion 71 is made up of a frame-shaped board clamping portion 72 having a U-shaped cross section and clamping the outer periphery of the sound-absorbing board 10 therein, and an extending portion 73 extending laterally from the board clamping portion 72 so as to move away from the sound-absorbing board 10. The extending portion 73 is provided with a positioning hole 73A that penetrates vertically. A positioning protrusion 63T provided on the upper surface of the rearmost support protrusion 63 is fitted into this positioning hole 73A, thereby fixing the package tray 70 to the sidewall 62. Note that in this embodiment, the extending portion 73 is provided with the positioning hole 73A, but this is not essential. In this case, the support protrusion 63 does not need to be provided with the positioning protrusion 63T in accordance with the shape of the extension 73.

[0077] As in this embodiment, by using the sound-absorbing board 10 for the package tray 70 of the vehicle 60, it is possible to absorb sound generated from the passenger compartment 60R side and the luggage compartment 60N side while ensuring the rigidity of the package tray 70. Conventionally, in order to ensure the rigidity of the package tray, the package tray has been shaped such that the outer edge is bent or that multiple locations are raised in the thickness direction to form an uneven shape. In contrast, in the package tray 70 of this embodiment, rigidity is ensured by the sound-absorbing board 10 having the impregnated layer 22, so the sound-absorbing board 10 can be made flat and the package tray 70 can be made compact in the thickness direction. This allows for wider use of the luggage compartment 60N and the passenger compartment 60R.

[0078] 7(A) and 7(B) show an example in which the sound-absorbing board 10 is provided on a luggage board 75 for a vehicle 60. The luggage board 75 is disposed in a luggage compartment 60N of the vehicle 60. An upwardly opening storage recess 65 is provided in the bottom of the luggage compartment 60N of the vehicle 60, and a spare tire 66 is stored in the storage recess 65. The luggage board 75 is placed on an opening edge 67 of the storage recess 65 to close the storage recess 65.

[0079] As shown in FIG. 7(B), the luggage board 75 is configured such that the sound-absorbing board 10 is layered on top of a sound-insulating panel material 76. In detail, the luggage board 75 is provided with a frame-shaped fixing portion 77 having a U-shaped cross section and sandwiching the outer peripheries of the sound-absorbing board 10 and the panel material 76 on its inner side, and the sound-absorbing board 10 and the panel material 76 are fixed by the fixing portion 77. The sound-absorbing board 10 and the panel material 76 may be integrated by the fixing portion 77 without being bonded, or may be integrated by bonding only a portion of the sound-absorbing board 10 and the panel material 76 with, for example, an adhesive, double-sided tape, hook-and-loop fastener, etc. The panel material 76 may be made of, for example, a wood board, a reinforced resin such as fiber-reinforced resin, or a metal plate.

[0080] In the luggage board 75, since the sound-absorbing board 10 itself has high rigidity, it is possible to reduce the thickness of the panel material 76. This allows the luggage board 75 to be made lighter.

[0081] As described above, the luggage board 75 is configured such that the sound-absorbing board 10 is overlapped on at least the upper surface of the panel material 76 having sound insulation properties. This allows the luggage board 75 to insulate sound and also absorb sound from the luggage compartment 60N side (vehicle interior 60R side). If the luggage board 75 is configured such that the sound-absorbing board 10 also overlaps the lower surface of the panel material, it becomes possible to absorb sound from below the luggage board 75. The sound-absorbing board 10 arranged on the upper surface side of the panel material 76 may overlap only a portion of the upper surface of the panel 76, but it is preferable that it overlap the entire upper surface of the panel 76. The sound-absorbing board 10 arranged on the lower surface side of the panel material 76 may overlap the entire lower surface of the panel 76, but it is preferable that it overlap only a portion of the lower surface of the panel 76.

[0082] If the solid-borne sound from the panel material 76 to the sound-absorbing board 10 becomes large, the sound absorption properties of the luggage board 75 may be reduced, and therefore it is preferable that the sound-absorbing board 10 and the panel material 76 are not entirely bonded together. Specifically, it is more preferable that the sound-absorbing board 10 and the panel material 76 are integrated together using, for example, a fixing portion 77, rather than by bonding the sound-absorbing board 10 and the panel material 76 together. Furthermore, when bonding the sound-absorbing board 10 and the panel material 76 together, it is preferable that only a portion of the sound-absorbing board 10 and the panel material 76 are bonded together. As described above, the sound-absorbing board 10 can suppress warping, and therefore it is possible to prevent gaps from occurring between the sound-absorbing board 10 and the panel material 76 even when the sound-absorbing board 10 and the panel material 76 are fixed together only by the fixing portion 77.

[0083] 8 shows another example of use of the sound-absorbing board 10. In this example, the sound-absorbing board 10 is provided in a sound-insulating structure 80 of a building 90.

[0084] In the building 90, a base 92, joists 93, and floor joists 94 are assembled on a foundation 91, and floorboards 95 are laid on the floor joists 94. In addition, a plurality of pillars (not shown) rise from the base 92, and beams 96 cross the middle of the plurality of pillars. The beams 96 and the floorboards 95 are connected by a double wall 81. The double wall 81 separates adjacent rooms 90R of the building 90.

[0085] The double wall 81 is composed of a pair of wall members 82 facing each other at a distance. The soundproof structure 80 of this example is formed by disposing a sound-absorbing board 10 between the pair of wall members 82, which are made of sound-insulating materials such as steel plates, gypsum boards, or concrete. In the soundproof structure 80, the surface (skin material 20) of the sound-absorbing board 10 is directly attached to the pair of wall members 82 without using adhesive or the like. In the soundproof structure 80, the wall members 82 and the skin material 20 of the sound-absorbing board 10 are not bonded together with adhesive or pressure-sensitive adhesive, but are in close contact without bonding. This ensures breathability of the skin material 20 of the sound-absorbing board 10. This allows the sound-absorbing board 10 to absorb sound transmitted through the wall members 82 from the room 90R. This reduces sound leakage into the adjacent room 90R compared to when the sound-absorbing board 10 is not disposed between the pair of wall members 82 or when the wall members 82 and the sound-absorbing board 10 are fixed together with adhesive. That is, the sound-insulating structure 80 can improve the sound-insulating properties of the double wall 81. In this example, the wall member 82 corresponds to the "panel material" described in the claims.

[0086] [Other embodiments] (1) The sound-absorbing board 10 may be manufactured by a manufacturing line 100 as follows. As shown in FIG. 9 , the manufacturing line 100 is equipped with a conveying means 101 (e.g., a conveyor) that conveys a pair of long, vertically facing skin materials 20 in the longitudinal direction. While the skin materials 20 are being conveyed, raw material 11M of polyurethane foam 11 is dispensed between the skin materials 20, and the raw material 11M is foamed and cured to form polyurethane foam 11. At this time, raw material 11M of polyurethane foam 11 impregnates the pair of skin materials 20, forming an impregnation layer 22 in each skin material 20. The skin materials 20, together with the polyurethane foam 11, are then cut to a predetermined length by a cutter 103 to obtain the sound-absorbing board 10. If the polyurethane foam 11 protrudes from the skin materials 20 at the widthwise ends of the sound-absorbing board 10, the protruding portions are trimmed appropriately. Furthermore, if a heating furnace 102 is provided midway along the conveying path of the conveying means 101, foaming and curing of the raw material 11M of the polyurethane foam 11 is accelerated, and the formability of the sound absorbing board 10 can be improved.

[0087] (2) The impregnation layer 22 may be formed from the surface of the skin 20 facing the polyurethane foam 11 to a position partway in the thickness direction of the inner fiber sheet 21A, or from the facing surface to a position partway in the thickness direction of the outer fiber sheet 21B. The impregnation layer 22 may be formed over the entire thickness direction of the skin 20 as long as the raw material 11M of the polyurethane foam 11 does not seep out to the outside of the sound-absorbing board 10.

[0088] (3) When the covering material 20 is formed of a fiber sheet 21, the covering material 20 may be formed of one fiber sheet 21 or three or more fiber sheets 21. The upper limit of the number of fiber sheets 21 that constitute the covering material 20 is not particularly limited and may be set appropriately depending on the purpose, but is preferably 10 sheets or less, and more preferably 5 sheets or less. When the covering material 20 is formed of one fiber sheet 21, in order to prevent the raw material 11M of the polyurethane foam 11 from leaking out of the covering material 20, the fiber diameter should be as thin as 2 to 4 denier, and a resin other than polyurethane-based resin should be attached to the fiber sheet 21 to adjust (increase) the basis weight of the fiber sheet 21. Furthermore, when the covering material 20 is made up of three or more fiber sheets 21, in order to prevent the raw material 11M of the polyurethane foam 11 from leaking out of the covering material 20, similar to the fiber sheets 21, 21 (inner fiber sheet 21A, outer fiber sheet 21B) of this embodiment, it is preferable to use fine fibers with a fiber diameter of 2 to 4 deniers for the fiber sheet 21 on the side in contact with the polyurethane foam 11 and to have a resin other than polyurethane-based resin attached to it.

[0089] (4) The configurations of a pair of skin materials 20 may be different. In this case, the type of fiber, basis weight, thickness, etc. may be different between the pair of skin materials 20. Furthermore, when the skin materials 20 are made of fiber sheets 21, the number of fiber sheets 21 constituting each of the pair of skin materials 20 may be different.

[0090] (5) In the above embodiment, the acrylic ester resin is impregnated only into the inner fiber sheet 21A of the skin material 20. However, the acrylic ester resin may be impregnated only into the outer fiber sheet 21B, or may be impregnated into the entire skin material 20, or may not be impregnated into the skin material 20.

[0091] (6) The covering material 20 only needs to be breathable, and the base sheet of the covering material 20 may be mesh-like or may have a large number of holes therethrough.

[0092] (7) The sound-absorbing board 10 may be used in a package tray of a sedan-type vehicle. In this case, the package tray is placed across a pair of opposing side walls of the vehicle, sandwiching a space behind the rear seat, to separate the space from the passenger compartment.

[0093] (8) In the above embodiment, in the sound-insulating structure 80, a pair of panel materials (wall members 82) sandwiching the sound-absorbing board 10 constitutes the double wall 81. However, the pair of panel materials sandwiching the sound-absorbing board 10 may also constitute a double floor or a double ceiling. In this case, too, the sound-absorbing board 10 may be disposed in a non-adhered state relative to the pair of panel materials. [Explanation of symbols]

[0094] 10 Sound-absorbing board 11 Polyurethane foam 11M raw materials 20 Skin material 22 Impregnated layer 70 Package Tray 75 Luggage board 80 Soundproofing structure

Claims

[Claim 1] The reverberation chamber sound absorption coefficient based on JIS A1409:1998 is 0.4 or more, The ratio of 50% compression hardness based on JIS K6400-2 E Method: 2012, wherein the ratio of the 50% compression hardness when the sound-absorbing board is compressed from one of the front and back sides to the 50% compression hardness when the sound-absorbing board is compressed from the other side is 70 to 143%, A sound-absorbing board in which polyurethane foam is molded integrally with the surface material.

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