Sound-absorbing structure and method for manufacturing the same

Abstract

To obtain a sound-absorbing structure with even better sound-absorbing properties by using thinner and lighter materials. [Solution] The hollow plate material has a structure in which multiple openings are formed in one of the upper and lower walls, and the main surface of the hollow plate material in which multiple cells are arranged side by side is laminated with a skin layer made of a film-like material with smooth surfaces on both sides, and the surface of the skin layer is made of resin and has a density of 5 to 200 mg / cm³ 3 The sound-absorbing structure has a nonwoven fabric layer with a thickness of 0.5 to 20.0 mm, which is welded to an intermediate layer having one or more of the structures described in A to C below. A: An intermediate layer in which some of the fibers of the nonwoven fabric layer are embedded within the skin layer while maintaining their fiber shape. (i): An intermediate layer having a structure in which some of the fibers of the nonwoven fabric layer are temporarily melted and adhered to the surface of the skin layer. (c) An intermediate layer having a structure in which the surface of the skin layer and some of the fibers of the nonwoven fabric layer are both melted and then mixed together.

Description

[Technical Field]

[0001] This invention relates to a sound-absorbing structure and a method for manufacturing the same. [Background technology]

[0002] Patent Document 1 describes a sound-absorbing structure which is a hollow structure in which multiple communication holes are formed on the upper surface of a hollow structure with multiple cells erected inside, and a nonwoven fabric layer is provided to improve sound absorption performance. However, as described in the embodiment, the nonwoven fabric layer is provided by "attaching" it. Judging from the fact that it is "attached," it is attached with an adhesive or adhesive agent, and no other means or structure is shown. Patent Document 2 describes a composite sound-absorbing material that consists of a sound-absorbing layer such as urethane foam or glass wool, a shielding plate, and a protruding plate layered on top of each other, with holes penetrating the sound-absorbing layer and the shielding plate. Patent Document 3 describes a laminate consisting of two layers: a thermoplastic synthetic resin layer containing a fiber reinforcement material and a nonwoven fabric layer made of two types of fibers. In the manufacture of this laminate, the entire nonwoven fabric layer is heated and pressurized together with the thermoplastic synthetic resin layer by heating during compression molding. Patent Document 4 describes a laminated nonwoven fabric that can be used in air filters, liquid filters, vacuum cleaner filters, etc., in which a specific thermoplastic long fiber layer is used as the upper and lower layer, a specific thermoplastic fine fiber layer is used as the middle layer, and each layer is integrated by point bonding with heat. Furthermore, Patent Document 5 describes a composite nonwoven fabric for sound absorption in which a short-fiber nonwoven fabric containing crimped hollow fibers and a sound-absorbing film layer made of a synthetic resin film are laminated by heat fusion. In particular, it is essential to use a short-fiber nonwoven fabric containing crimped hollow fibers, and it does not suggest that other melt-frame nonwoven fabrics can be similarly laminated to the film layer with a hot-melt adhesive. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2017-65026 [Patent Document 2] Japanese Patent Publication No. 2018-194649 [Patent Document 3] International Publication No. 2012-164977 [Patent Document 4] Japanese Patent Publication No. 2010-121261 [Patent Document 5] Japanese Patent Publication No. 2015-174398 [Overview of the project] [Problems that the invention aims to solve]

[0004] The sound-absorbing structures described in the above-mentioned patent documents have been able to improve sound absorption to some extent. However, their properties are still not sufficient. Moreover, the invention described in Patent Document 4 is a laminate intended for use in air filters, liquid filters, vacuum cleaner filters, etc., and is designed to actively allow gases to pass through, and is not intended to provide excellent sound absorption. The present invention aims to obtain a sound-absorbing structure with even better sound absorption properties using thinner and lighter materials. [Means for solving the problem]

[0005] 1. The structure comprises side walls that are erected in the thickness direction to partition the cells, and upper and lower walls provided at the edges of the side walls, with multiple openings formed in one of the upper and lower walls, and a skin layer made of a film-like material with smooth surfaces on both sides is laminated on the main surface of the hollow plate material in which multiple cells are arranged side by side, and the surface of the skin layer and a resin with a density of 5 to 200 mg / cm³ 3 The sound-absorbing structure has a nonwoven fabric layer with a thickness of 0.5 to 20.0 mm, which is welded to an intermediate layer having one or more of the structures described in A to C below. A: An intermediate layer in which some of the fibers of the nonwoven fabric layer are embedded within the skin layer while maintaining their fiber shape. (i): An intermediate layer having a structure in which some of the fibers of the nonwoven fabric layer are temporarily melted and adhered to the surface of the skin layer. (c) An intermediate layer having a structure in which the surface of the skin layer and some of the fibers of the nonwoven fabric layer are both melted and then mixed together. 2. The sound-absorbing structure according to claim 1, wherein a plurality of holes are formed in the skin layer. 3. The sound-absorbing structure according to claim 2, wherein, as the distribution of inner diameters of holes on the nonwoven fabric layer side of the skin layer provided on one wall portion, when the average value of the inner diameters is set to 100, 30% to 70% of the total number of holes have an inner diameter of 80% to 120% of the average value of the inner diameters. 4.A. It comprises side wall portions erected in the thickness direction to partition the cells, and upper and lower wall portions provided at the edges of the side wall portions, The upper wall portion and one of the lower wall portions have a structure in which a plurality of openings are formed, and the skin layer surface is formed by laminating a skin layer made of a film-like material with smooth surfaces on both sides onto the main surface of a hollow plate material in which a plurality of cells are arranged side by side. and / or, The skin layer side of the nonwoven fabric layer made of resin fibers, The process of heating, B. A step of pressing the surface of the skin layer and the skin layer side of the nonwoven fabric layer together. It has the following in order: The skin layer is laminated onto the main surface of a hollow plate material in which multiple cells are arranged side by side, and the surface of the skin layer is made of resin with a density of 5 to 200 mg / cm³. 3 A method for manufacturing a sound-absorbing structure having a nonwoven fabric layer with a thickness of 0.5 to 20.0 mm welded together via an intermediate layer having one or more of the structures described in A to C below. A: An intermediate layer in which some of the fibers of the nonwoven fabric layer are embedded within the skin layer while maintaining their fiber shape. (i): An intermediate layer having only a structure in which some of the fibers of the nonwoven fabric layer have melted and adhered to the surface of the skin layer. U: An intermediate layer having a structure in which the surface of the skin layer and some of the fibers of the nonwoven fabric layer are both melted and then mixed together. 5.C. A step of heating the surface of a skin layer made of a film-like material with smooth surfaces on both sides, and / or the skin layer side of a nonwoven fabric layer made of resin fibers. Step D: Obtaining a laminate through crimping the surface of the skin layer and the side of the non-woven fabric layer on the skin layer side, with an intermediate layer having any one or more of the following structures a to u: Step E: The surface on the skin layer side of the obtained laminate, A hollow plate material having side wall portions erected in the thickness direction to partition cells, and upper wall portions and lower wall portions provided at the edges of the side wall portions, A hollow plate material having side wall portions erected in the thickness direction to partition cells, and upper wall portions and lower wall portions provided at the edges of the side wall portions, with a structure in which a plurality of openings are formed in one of the wall portions of the upper wall portion and the lower wall portion, and a plurality of cells are arranged side by side, laminating the main surface of the hollow plate material, Step of laminating, Containing, The skin layer is laminated on the main surface of a hollow plate material in which a plurality of cells are arranged side by side, and a non-woven fabric layer made of resin fibers with a density of 5 to 200 mg / cm 3 and a thickness of 0.5 to 20.0 mm is welded to the surface of the skin layer. A method for manufacturing a sound-absorbing structure having such a structure. A: An intermediate layer formed by burying a part of the fibers of the non-woven fabric layer in the skin layer while maintaining their fiber shapes B: An intermediate layer having only a structure in which a part of the fibers of the non-woven fabric layer are once melted and adhered to the surface of the skin layer U: An intermediate layer having a structure in which the surface of the skin layer and a part of the fibers of the non-woven fabric layer are both once melted and compatible

Advantages of the Invention

[0006] In the present invention, since the non-woven fabric is laminated so as to form and fix a specific intermediate layer formed on the skin layer, the non-woven fabric layer can be provided more reliably, and while having excellent sound-absorbing characteristics, it can be made thinner than conventional sound-absorbing structures. Also, even when processed into a three-dimensional shape after lamination, the skin layer and the non-woven fabric layer do not peel off from each other.

Brief Description of the Drawings

[0007] [Figure 1](a) is a perspective view of only the core layer and the skin layer among the sound-absorbing structures of the first embodiment, (b) is a cross-sectional view taken along the line α-α with the non-woven fabric layer provided in (a), and (c) is a cross-sectional view taken along the line β-β with the non-woven fabric layer provided in (a). [Figure 2] A diagram showing a mode of welding the skin layer and the non-woven fabric while forming the intermediate layer in the present invention.

Embodiments for Carrying out the Invention

[0008] Hereinafter, an example of the sound-absorbing structure of the present invention will be described according to FIG. 1. (Outline of a hollow plate material with a plurality of cells arranged side by side and a skin layer) FIG. 1(a) shows a hollow plate material (hereinafter referred to as "core layer or core layer 20") in which a plurality of cells are arranged side by side in a state where the skin layer 30 and the non-woven fabric layer are not provided in the sound-absorbing structure of the present invention, and the skin layer 30 is laminated on the main surface, and holes 15 are formed to communicate the core layer 20 with the outside of the sound-absorbing structure. And it is composed of a core layer 20 in which a plurality of cells S are arranged side by side inside, a skin layer 30 in the form of a film or sheet with smooth surfaces on both sides joined to the upper surface of the core layer 20, and a sheet-like skin layer 40 joined to the lower surface of the core layer 20. The core layer 20 and the skin layers 30 and 40 in the present invention may both be made of a thermoplastic resin, or only one of them may be made of a thermoplastic resin. Further, the core layer 20 and the skin layers 30 and 40 are not made of woven fabric or non-woven fabric, but are made of resin sheet-like materials. This main surface refers to the sound source side of the sound to be absorbed when the sound-absorbing structure of the present invention is used.

[0009] As shown in Figures 1(b) and 1(c), the core layer 20 may be formed by folding a single thermoplastic resin sheet material molded into a predetermined shape. The core layer 20 is composed of an upper wall portion 21, a lower wall portion 22, and a side wall portion 23 erected between the upper wall portion 21 and the lower wall portion 22 to partition the cells S (S1 and S2 in the figure) into a hexagonal prism shape. The upper wall portion and the lower wall portion are provided to cover the cells S from above and below. The size of the cells S is not particularly limited, but for example, the distance between opposite sides of the regular hexagonal cross-sectional shape of the cells S is preferably about 5 to 20 mm. Furthermore, the height of the cells S in the thickness direction of the sound-absorbing structure 10 is preferably about 5 to 40 mm, and more preferably about 10 to 30 mm. The thickness of the single thermoplastic resin sheet material used to form the core layer is not particularly limited, but is a fraction of the thickness of the formed core layer (preferably 0.2 to 5.0 mm, more preferably 0.2 to 3.0 mm, and even more preferably 0.3 to 2.0 mm). Shinsa

[0010] As shown in Figures 1(b) and 1(c), the cells S partitioned within the core layer 20 include a first cell S1 and a second cell S2 with different configurations. As shown in Figure 1(b), in the first cell S1, a two-layer upper wall 21 is provided above the side wall 23. Each layer of this two-layer upper wall 21 is joined to the others. Also in the first cell S1, a single-layer lower wall 22 is provided below the side wall 23. On the other hand, as shown in Figure 1(c), in the second cell S2, a single-layer upper wall 21 is provided above the side wall 23. Also in the second cell S2, a two-layer lower wall 22 is provided below the side wall 23. Each layer of this two-layer lower wall 22 is joined to the others. Furthermore, as shown in Figures 1(b) and 1(c), adjacent first cells S1 and adjacent second cells S2 are partitioned between each other by two-layer side wall 23s. In Figure 1(a), the upper wall portion 21 and the lower wall portion 22 of the core layer 20 are shown as a single-layer structure.

[0011] As shown in Figure 1(a), the first cells S1 are arranged in a row along the X direction, and when viewed from above, two adjacent first cells S1 share one side of a hexagon. Similarly, the second cells S2 are arranged in a row along the X direction, and when viewed from above, two adjacent second cells S2 share one side of a hexagon. The rows of first cells S1 and second cells S2 are arranged alternately in the Y direction, which is perpendicular to the X direction. These first cells S1 and second cells S2 form a honeycomb structure as a whole in the core layer 20.

[0012] Furthermore, from the viewpoint of improving sound insulation, it is preferable that the sheet is non-breathable. From the viewpoint of improving sound insulation, the specific gravity of the sheet material should be 0.9 g / m². 3 Preferably, the above. The basis weight of the sheet material is 1000 g / m². 2 The above is preferable. The higher the specific gravity of the sheet material, the more significant the increase in acoustic loss transmission effect from the low-frequency range. Here, the low-frequency range refers to the range of approximately 200Hz to 400Hz. The same applies to the following explanation.

[0013] The core layer in this invention is not limited to the core layer described above. Any core layer that can be used for sound absorption is acceptable, and the cross-section of the core layer on a plane parallel to the surface may be any shape, such as a hexagonal honeycomb, square, triangular, irregular, or circular. Furthermore, the cross-sectional shape of the core layer on a plane perpendicular to the surface may be any shape, such as a rectangle, square, trapezoid, or other irregular shape. In addition to the skin layer in this invention, a thin layer may be formed on both sides or one side of the core layer. Furthermore, if the skin layer has holes in the thickness direction of the layer, it is preferable that the thin layer also has corresponding holes at positions that match the holes in the skin layer in order to obtain excellent sound absorption. The skin layer does not have to have holes.

[0014] As shown in Figures 1(a) to 1(c), a skin layer 30 is bonded to the upper surface of the core layer 20, and a skin layer 40 is bonded to the lower surface of the core layer 20, forming a sound-absorbing structure 10. Therefore, the upper edge of the side wall portion 23 of the core layer 20 is provided with the upper wall portion 21 of the core layer 20 and the skin layer 30, thereby closing off the cell S. Similarly, the lower edge of the side wall portion 23 of the core layer 20 is provided with the lower wall portion 22 of the core layer 20 and the skin layer 40, thereby closing off the cell S. If a nonwoven fabric layer is not provided on the surface of the skin layer 30 and skin layer 40 via an intermediate layer, the skin layer itself may or may not be provided. Note that in Figures 1(b) and (c), the leftmost cell S of the three cells S shown is given as a representative reference number, but the same applies to the other cells S. In this case, the upper wall portion 21 and the lower wall portion 22 may be formed in conjunction with the formation of the core layer 20, which is formed by folding a single sheet of thermoplastic resin material molded into a predetermined shape, as shown in Figures 1(b) and 1(c). In this case, the thickness of the upper wall portion 21 and the lower wall portion 22 may be independently the thickness of one sheet of thermoplastic resin material or the thickness of two sheets. In Figures 1(b) and 1(c), the upper wall portion 21 and the lower wall portion 22 are each formed to have a thickness equivalent to two sheets of thermoplastic resin material folded.

[0015] As shown in Figures 1(b) and (c), the upper surface 10a of the sound-absorbing structure 10 is provided with holes 15 that connect the inside and outside of the cell S. Specifically, as shown in Figure 1(b), in the first cell S1, the holes 15 are provided so as to penetrate the upper skin layer 30 and the upper wall portion 21 of the two-layer structure. Also, as shown in Figure 1(c), in the second cell S2, the holes 15 are provided so as to penetrate the upper skin layer 30 and the upper wall portion 21 of the single-layer structure. In other words, the holes 15 are provided in the closing walls of each cell S that close the upper part of the side wall portion 23.

[0016] In Figure 1, multiple holes 15 are formed so as to be arranged side by side in the vertical and horizontal directions (X and Y directions in Figure 1(a)) of the skin layer 30. The formation pitch in both the vertical and horizontal directions is regularly spaced at equal intervals. Furthermore, the formation pitch of the holes 15 may be smaller than the formation pitch of the cells S, and may be approximately 1 / 5 to 5 / 5 or 1 / 5 to 3 / 5 of the formation pitch of the cells S. Therefore, multiple holes 15 are formed for each cell S of the core layer 20. Note that the formation pitch of the cells S refers to the distance between the centers of adjacent cells S that share one side of a hexagon. Note that the formation pitch of the holes 15 and the formation pitch of the cells S may be the same. In this case, holes can be formed at similar positions in the skin layer of each cell.

[0017] The shape of the hole 15 is not particularly limited, but may be round, rectangular, or irregular in shape when viewed from above. The size of the hole 15 is also not particularly limited, but from the viewpoint of good sound absorption of the sound-absorbing structure, it is preferable that the diameter of the hole 15 be about 1 / 20 to 1 / 5 of the distance between opposite sides of the regular hexagonal cross-sectional shape of the cell S. For example, the diameter of the hole 15 is preferably about 0.25 to 4.0 mm, and more preferably about 0.5 to 1.5 mm. As for the distribution of inner diameters of the holes on the nonwoven fabric layer side of the skin layer provided on one wall, when the average value of the inner diameter is set to 100, 30% to 70% of the total number of holes may have an inner diameter of 80% to 120% of the average inner diameter. This average inner diameter is the average pore diameter of the skin layer surface portion of 300 randomly selected holes 15.

[0018] Holes with such an inner diameter distribution can be achieved by adjusting the conditions of the process of welding the skin layer surface and the nonwoven fabric to form an intermediate layer. In this welding process, the skin layer and / or nonwoven fabric are melted and pressurized so that the skin layer and nonwoven fabric are integrated through the intermediate layer by welding. The molten resin then flows into the inside of the holes from the openings, partially blocking the openings, resulting in the inner diameter distribution of the hole openings described above. Alternatively, holes may be formed in these layers after the nonwoven fabric has been welded to the surface of the skin layer.

[0019] As shown in Figures 1(b) and 1(c), when the formation pitch of the holes 15 is the same as the formation pitch of the cell S, the holes 15 are formed at the same positions in the first cell S1 and the second cell S2. The multiple holes 15 formed in the skin layer 30 are formed at the same positions as the first holes 15a formed in the cell. Furthermore, if the formation pitch of the holes 15 is smaller than the formation pitch of the cells S, multiple holes may be formed in a single cell S.

[0020] Furthermore, when a hole 15 is formed by perforating with a needle or the like after the skin layer 30 has been formed, thereby connecting the inside and outside of the cell S, as shown in Figures 1(b) and (c), the hole 15 has a structure consisting of a convexly bent skin layer 30 and an upper wall portion 21, facing inward as a convex body. Furthermore, the thickness of the skin layer is not particularly limited as long as it has sufficient strength to withstand welding with the nonwoven fabric, but is preferably 0.2 to 5.0 mm, more preferably 0.2 to 3.0 mm, and even more preferably 0.3 to 2.0 mm.

[0021] (Nonwoven fabric layer with an intermediate layer) The sound-absorbing structure of the present invention has a structure in which a nonwoven fabric layer made of resin fibers is laminated on a skin layer 30 provided on the main surface of the core layer 20, via an intermediate layer formed by welding a nonwoven fabric (not shown in Figure 1(a)) (hereinafter sometimes simply referred to as the "nonwoven fabric layer"). In this case, when the skin layer 30 is provided on the upper wall portion 21 provided on the core layer 20 as described above, if the upper wall portion 21 is formed by folding a thermoplastic resin sheet material, then a surface layer consisting of substantially two layers (one upper wall portion 21 and the skin layer) is formed on the surface of the core layer 20. As shown in Figure 1(b), if the upper wall portion 21 is formed by folding a thermoplastic resin sheet material, then a surface layer consisting of substantially three layers (two upper wall portions 21 and the skin layer) is formed on the surface of the core layer 20.

[0022] In this invention, the nonwoven fabric before lamination onto the skin layer is referred to as the nonwoven fabric, and the portion where the structure of the nonwoven fabric remains unchanged after lamination is referred to as the nonwoven fabric layer. The individual fibers constituting the nonwoven fabric may be solid inside, may have pores inside, or may be hollow and tubular. However, considering the welding strength and sound absorption properties of the nonwoven fabric, it is desirable for the fibers to be solid. Furthermore, nonwoven fabrics are preferably composed solely of fibers, although they may also be composed of fibers and a binder such as resin. However, if a resin binder is included, or if the fibers constituting the nonwoven fabric are combined so that they have two or more melting points, and the resin forming the intermediate layer consists mainly of low-melting-point fibers, lamination to other materials becomes easier, but the sound absorption tends to decrease. Furthermore, the sound-absorbing structure of the present invention is not intended to be subjected to subsequent processing involving heating, such as hot pressing, to form a bent portion with a large curvature, as shown in the figure of International Publication No. 2012 / 164977. However, even when processing involving heating is performed, the fibers forming the nonwoven fabric layer do not have fibers with a melting point that would cause the entire nonwoven fabric layer to melt during processing.

[0023] Schematic diagrams of the cross-section of the sound-absorbing structure after the nonwoven fabric layer has been applied are shown in Figures 2(a) to 2(c). The entire nonwoven fabric before the formation of the intermediate layer is not used for its formation; rather, only a portion of the layers on the skin-side of the nonwoven fabric are used for its formation. Even if it is a nonwoven fabric before welding onto the skin layer, after welding, if the nonwoven fabric layer is a mixture of fibers and a partially melted resin of the nonwoven fabric throughout the entire lengthwise direction of the nonwoven fabric, and is pressure-molded simultaneously with the heating for melting, then the nonwoven fabric layer formed on the skin layer together with the melted partially resin is not a nonwoven fabric layer in the present invention. Even when a nonwoven fabric layer is provided on the skin layer 30 via an intermediate layer, a nonwoven fabric layer may or may not be provided on the skin layer 40 side. If a nonwoven fabric layer is not provided on the skin layer 40 side, the skin layer 40 may or may not be provided.

[0024] Note that the thickness of the non-woven fabric layer is not particularly limited, but is preferably 0.5 mm or more, more preferably 2.0 mm or more, and even more preferably 4.0 mm or more. Also, it is preferably 20.0 mm or less, more preferably 17.0 mm or less, and even more preferably 15.0 mm or less. The sound-absorbing structure of the present invention is not obtained by leaving the thickness of the non-woven fabric used as it is. A part of the thickness is used to form the intermediate layer. Since 5 to 90% of the thickness of the non-woven fabric used is used to form the intermediate layer, the thickness of the non-woven fabric layer after obtaining the sound-absorbing structure is 10 to 95% of the thickness of the non-woven fabric used. Also, even if the non-woven fabric layer is provided on the surface of the skin layer via the intermediate layer by the following methods, the above-described holes 15 originally possessed by the skin layer are not blocked by the intermediate layer formed by the fibers of the melted skin layer and / or the melted non-woven fabric, and the non-woven fabric is laminated. Furthermore, the non-woven fabric layer does not undergo pressure molding that changes the shape of the laminate in the process of laminating the non-woven fabric on the skin layer.

[0025] The density of the non-woven fabric and the non-woven fabric portion of the non-woven fabric layer is 5 mg / cm 3 or more, or 10 mg / cm 3 or more, which is desirable. On the other hand, it is desirable to be 200 mg / cm 3 or less, or 100 mg / cm 3 or less. If the density is less than 5 mg / cm 3 , it is difficult to sufficiently improve the performance of the porous sound-absorbing material. Also, if the density exceeds 200 mg / cm 3 , it becomes difficult to make a lightweight sound-absorbing structure. 5 mg / cm 3 or more and 100 mg / cm 3 or less can make the sound-absorbing structure thinner and improve the sound-absorbing characteristics in a wide frequency range from mid-frequency to high-frequency.

[0026] The sound-absorbing structure of the present invention is not one in which the skin layer and the nonwoven fabric are simply in contact and laminated together, nor is it one in which the skin layer and the nonwoven fabric are laminated together via another layer such as an adhesive. Furthermore, it is not the case that the fibers on the surface of the nonwoven fabric are welded to the surface of the skin layer at points. The structure of the nonwoven fabric layer, which is formed by welding a nonwoven fabric to a skin layer via an intermediate layer, may be as follows: as shown in Figure 2(a), it may be a structure in which the fibers of the nonwoven fabric are embedded in an intermediate layer on the surface of the skin layer; as shown in Figure 2(b), it may be a structure in which the surface of a partially molten nonwoven fabric is welded to the surface of the skin layer; or as shown in Figure 2(c), it may be a structure having both of these structures, that is, a structure in which the surface of the nonwoven fabric is molten and the surface of the skin layer is also molten, and the molten parts of each are mixed to form an intermediate layer.

[0027] For example, these structures can be selectively formed by adjusting the relationship between the melting points of the skin layer and the nonwoven fabric and the temperature at which they are heated, as shown below. Note that before laminating the nonwoven fabric... If pores in the skin layer open into spaces within the core layer, it is necessary to consider the heating temperature and the material and structure of the skin layer so that these open pores are not substantially sealed even after the nonwoven fabric layer is formed on the skin layer. Alternatively, to create holes in the skin layer, a nonwoven fabric layer may be formed on the surface of the skin layer, and then a needle or the like may be inserted to penetrate these layers. Furthermore, the sound-absorbing structure of the present invention can be used for purposes other than wall materials, vehicle components, and floor materials, or as floor material. However, when used as floor material, the nonwoven fabric layer cannot be oriented toward the underside of the floor material, nor can the nonwoven fabric layer be installed in a manner that improves adhesion with the adhesive applied to the surface of the floor substrate.

[0028] (Structure of the intermediate layer) The intermediate layer in this invention is a layer having one or more of the following structures A to D. In all of these layers, the skin layer and the nonwoven fabric layer do not make point contact. a. An intermediate layer in which some of the fibers of the nonwoven fabric layer are embedded within the skin layer while maintaining their fiber shape. When the melting point of the nonwoven fabric is higher than the melting point of the skin layer (or when the nonwoven fabric is not thermoplastic), and the heating temperature of the skin layer surface exceeds the melting point of the skin layer but is lower than the melting point of the nonwoven fabric, the structure has an intermediate layer formed when the ends of the fibers constituting the nonwoven fabric enter the melted skin layer. The structure of this intermediate layer is such that the ends of the fibers constituting the nonwoven fabric penetrate the skin layer while maintaining the shape of the fibers.

[0029] i. An intermediate layer having a structure in which some of the fibers of the nonwoven fabric layer are temporarily melted and adhered to the surface of the skin layer. When the melting point of the nonwoven fabric fibers is lower than that of the skin layer, and the heating temperature is between these melting points, the ends of the nonwoven fabric fibers melt and are welded to the surface of the skin layer via a newly formed intermediate layer. The structure of this intermediate layer is such that the ends of the fibers constituting the nonwoven fabric melt and then solidify to form a layer, which is then a layer that exists on top of the original skin layer.

[0030] (c) An intermediate layer having a structure in which the surface of the skin layer and some of the fibers of the nonwoven fabric layer are both melted and then mixed together. When the heating temperature is higher than the melting point of the skin layer and the nonwoven fabric, the surfaces in contact with the skin layer and the nonwoven fabric melt together to form a single layer, creating a newly formed intermediate layer. The structure of this intermediate layer is such that both the ends of the fibers constituting the nonwoven fabric and the skin layer melt once, and at least a portion of the molten material becomes miscible and integrated. Furthermore, these intermediate layers themselves may not have through holes, or they may reduce the diameter of the through holes that the skin layer had. They do not form a breathable layer structure like a vacuum cleaner filter, which is simply multiple fiber layers bonded together at points. The intermediate layer is a layer derived from part of the skin layer and / or part of the nonwoven fabric layer, and is not a layer consisting only of two or more fiber layers. Therefore, even if the intermediate layer has holes, those holes are of a similar diameter to the holes in the original skin layer, or smaller in diameter.

[0031] In a structure where a skin layer and a nonwoven fabric layer are laminated with an intermediate layer in between, vibrations transmitted from a sound source cause the fibers constituting the nonwoven fabric layer to vibrate, and these vibrations are reliably transmitted through the intermediate layer to the skin layer, which is integrated with the ends of the fibers. It can then be expected that these vibrations will be directly and uniformly spread throughout the entire skin layer. As a result, when combined with a core layer made of hollow plate material, it is possible to exhibit characteristics that show a higher sound absorption coefficient and / or the effect of absorbing sound in a wider frequency range. In this way, the sound-absorbing structure of the present invention can exhibit superior sound absorption characteristics over a wider frequency range. This effect is superior to structures where the skin layer and nonwoven fabric are simply in contact. If the skin layer and nonwoven fabric are simply layered on top of each other, for example, vibrations generated by the sound absorption of the nonwoven fabric are not reliably transmitted to the core layer. Furthermore, even if an adhesive layer is formed between the skin layer and the nonwoven fabric to join the two layers, the presence of the adhesive layer makes it difficult for vibrations of the nonwoven fabric fibers transmitted from the sound source to be transmitted to the core layer.

[0032] Furthermore, as described above, the inner diameter distribution of the holes 15 on the nonwoven fabric layer side of the skin layer provided on one wall has a certain range, so in addition to the excellent sound absorption characteristics mentioned above, sound absorption can be performed more reliably even if the sound to be absorbed consists of a particularly wide range of frequencies. However, as an integrated configuration of the nonwoven fabric layer and the skin layer, a single fiber-containing resin layer, such as one formed by uniformly incorporating fibers into the resin, is not used.

[0033] Furthermore, an adhesive layer or tack layer may or may not be provided between the skin layer and the nonwoven fabric layer. If an adhesive layer or tack layer is provided, these materials may fill the pores formed in the skin layer before lamination, which may make it difficult to improve sound absorption. In addition, it may become excessively thick or peel off after prolonged use. If a method is employed in which holes are formed after the skin layer and nonwoven fabric layer are bonded together with an adhesive, the perforating member, such as a needle, moves perpendicular to the main surface of the hollow plate material, and if the adhesive layer is flexible, there is a concern that it may move together with the needle. As a result, there is a possibility that the nonwoven fabric may peel off from the skin layer, even partially. Consequently, vibrations generated by the sound absorption of the nonwoven fabric are less likely to be reliably transmitted to the core layer.

[0034] (Materials that make up each layer) As described above, the core layer 20 and skin layers 30 and 40 are preferably made of resin. The nonwoven fabric layer F contains resin. Among the resins, any conventionally known thermoplastic resin is acceptable, and examples of each are polyolefin resins such as polyethylene resin and polypropylene resin, polyamide resin, acrylonitrile-butadiene-styrene copolymer resin, acrylic resin, and polyester resins such as polybutylene terephthalate resin. Among these, polypropylene resin is preferred for the core layer 20. When a sheet material made of thermoplastic resin is used as the material for forming the core layer as described above, the upper wall portion 21 and the lower wall portion 22, which are formed at the same time, are also formed from the same material.

[0035] The thermoplastic resins constituting the skin layers 30 and 40 are preferably the same type of thermoplastic resin as the core layer 20 and the nonwoven fabric layer F. If these thermoplastic resins are independently polyolefin resins such as polyethylene resin or polypropylene resin, they can be strongly integrated with the skin layer and nonwoven fabric layer at an appropriate heating temperature, resulting in a stable laminated structure. Furthermore, the distribution of pores can be adjusted by adjusting the heating temperature, the melting point of each material, and the strength of the pressure applied during bonding. In addition, the pores in the skin layer will not be filled, as can occur when adhesives are used. Furthermore, a non-thermoplastic resin may be used instead of the thermoplastic resin, or a portion of the thermoplastic resin may be made of a non-thermoplastic resin. Furthermore, the nonwoven fabric layer F consists of one type of resin. This one type of resin includes two cases: when the fiber material consists of only one type of resin, and when fibers made from multiple types of resin materials are mixed, but only some of the resins do not melt during welding.

[0036] In addition to the resins mentioned above, other fibers such as metal fibers, inorganic fibers, and cellulose fibers may be included, provided that they do not impair adhesion with the skin layer. Alternatively, they may not be included. The core layer may be formed from a bubble-containing sheet made of porous material or foaming material, or it may be formed from a sheet that is neither porous nor foaming. The skin layer may consist of a sheet or film-like material with smooth surfaces on both sides. When laminated onto the core layer, the outer surface (the side on which the nonwoven fabric is laminated) does not need to have resin fibers. If resin fibers are present, the resulting structure may differ from the structure in the sound-absorbing structure of the present invention where the skin layer and the nonwoven fabric layer are welded together.

[0037] (Method of manufacturing sound-absorbing structures) One of two methods for manufacturing a sound-absorbing structure of the present invention, comprising a hollow plate material having a side wall portion erected in the thickness direction to partition cells, an upper wall portion and a lower wall portion provided at the edge of the side wall portion, wherein a plurality of cells are arranged side by side, each having a structure in which a plurality of openings are formed in one of the upper wall portion and the lower wall portion, wherein a skin layer is laminated on the main surface having the openings, and a nonwoven fabric layer is laminated on the skin layer via an intermediate layer, and the intermediate layer contains a material derived from a part of the fibers of the nonwoven fabric layer, is: A. It comprises side wall portions erected in the thickness direction to partition the cells, and upper and lower wall portions provided at the edges of the side wall portions, The upper wall portion and one of the lower wall portions have a structure in which a plurality of openings are formed, and only the surface of the skin layer, which is laminated on the main surface of a hollow plate material in which a plurality of cells are arranged side by side, and / or, Only the skin layer side of the nonwoven fabric, The process of heating, B. A step of pressing the surface of the skin layer and the skin layer side of the nonwoven fabric together. It has the following in order: This is a method for manufacturing a sound-absorbing structure having a structure in which the skin layer is laminated on the main surface of a hollow plate material in which a plurality of cells are arranged side by side, and the nonwoven fabric layer is welded to the surface of the skin layer via the intermediate layer.

[0038] Another of the two methods for obtaining the sound-absorbing structure of the present invention is: C. A step of heating only the surface of the skin layer and / or only the skin layer side of the nonwoven fabric. D. A step of obtaining a laminate by pressing the surface of the skin layer and the skin layer side of the nonwoven fabric together. E. The skin layer side surface of the obtained laminate, It comprises side wall portions erected in the thickness direction to partition cells, and upper and lower wall portions provided at the edges of the side wall portions, The main surface of the hollow plate material, which has multiple cells arranged side by side, is provided with side walls that are erected in the thickness direction to partition the cells, and upper and lower walls provided at the edges of the side walls, with multiple openings formed in one of the upper and lower walls, The process of lamination, Contains This is a method for manufacturing a sound-absorbing structure having a structure in which the skin layer is laminated on the main surface of a hollow plate material in which a plurality of cells are arranged side by side, and the nonwoven fabric layer is welded to the surface of the skin layer via the intermediate layer. When laminating these layers, pressure welding can be performed using rollers or pressure plates as needed. Furthermore, any heating method that can uniformly heat the surface to be heated is acceptable, and well-known methods can be employed.

[0039] (Method for forming the intermediate layer) Furthermore, for each of the two methods described above to obtain the intermediate layer of structures A to C, three different methods of laminating the nonwoven fabric layer and skin layer, corresponding to structures A to C, can be employed, as described below (a to c). It is preferable for superior sound absorption effect to heat the entire surface on the side of the skin layer and / or nonwoven fabric layer that forms the intermediate layer. Alternatively, the intermediate layer may be formed by heating a portion of each surface on the side of the skin layer and the nonwoven fabric layer that forms the intermediate layer. The intermediate layer in the obtained sound-absorbing structure may be formed in the direction of the entire sound-absorbing structure, or it may be provided on a portion of the surface. Note that the entire thickness direction of the nonwoven fabric layer is not heated.

[0040] a. A method in which the surface of the skin layer is heated in advance to the extent that only the surface melts, and a nonwoven fabric is pressed onto that surface, thereby embedding some of the fibers of the nonwoven fabric within the skin layer without melting them. A schematic cross-sectional view of the laminated structure of the skin layer and nonwoven fabric layer obtained by this method is shown in Figure 2(a). In this figure, some of the fibers of the nonwoven fabric are present in the skin layer to form an intermediate layer, and the other parts of the nonwoven fabric have the structure of a nonwoven fabric. In this case, it is preferable that the depth to which the fibers are embedded from the surface of the skin layer is 0.1 μm or more.

[0041] b. A method in which one side of the nonwoven fabric is heated in advance to partially melt it, and the melted side of the nonwoven fabric is pressed against the surface of the skin layer to form an intermediate layer on the surface of the skin layer, in which the fibers of the nonwoven fabric surface are melted, and the nonwoven fabric layer is welded by this intermediate layer. A schematic diagram of the cross-section of the laminated structure of the skin layer and nonwoven fabric layer obtained by this method is shown in Figure 2(b). In this figure, a layer in which some of the fibers of the nonwoven fabric are melted exists on the skin layer as an intermediate layer, and the other part of the nonwoven fabric has the structure of a nonwoven fabric layer. In this case, it is preferable that the proportion of the area on the surface of the skin layer in which the nonwoven fabric fibers are welded is 10% or more.

[0042] c. A method in which the surface of the skin layer is heated in advance to the extent that it melts, and if necessary, one side of the nonwoven fabric is heated in advance to partially melt it, and the melted surface of the skin layer and, if necessary, some of the melted fibers of the nonwoven fabric are pressed together, causing the fibers of the nonwoven fabric and the resin of the skin layer to melt and mix, integrating them into one. A schematic cross-sectional view of the laminated structure of the skin layer and nonwoven fabric layer obtained by this method is shown in Figure 2(c). In this figure, a layer in which some of the fibers of the nonwoven fabric have melted together with the resin on the surface of the skin layer and become integrated exists as an intermediate layer on the surface of the skin layer, while the other parts of the nonwoven fabric have the structure of a nonwoven fabric.

[0043] In all cases, the process of creating holes in the skin layer can be carried out at any of three stages: before laminating the skin layer onto the core layer, after laminating the skin layer onto the core layer, or after laminating the nonwoven fabric onto the skin layer. In the structure shown in Figure 1(a), when creating holes 15 in the skin layer by piercing it with a needle or the like, an opening may also be created in one wall of the core layer at the same time. In this case, both holes 15 and the opening can be created in a single step. Furthermore, when heating the nonwoven fabric, do not heat it so that the entire thickness of the nonwoven fabric melts. If the entire thickness of the nonwoven fabric is heated above its melting point, it will not have the structure of a nonwoven fabric. For this reason, it is sufficient to heat at least one or part of the surface of the opposing surfaces of these layers that are laminated together. However, it is also possible to use a means such as a needle for forming holes as a heating element, and after the skin layer and nonwoven fabric are stacked, heat both layers at the same time as creating holes to weld them together, or not. If this means is adopted, the area of ​​the part where the resin has melted and welded together is small, so it may be difficult to efficiently transmit vibrations of the nonwoven fabric layer to the skin layer.

[0044] (Sound-absorbing structure obtained by method a) The sound-absorbing structure obtained by method a above has an intermediate layer in which the fibers from the surface of the nonwoven fabric before lamination are embedded within the skin layer. Even in the sound-absorbing structure obtained by method a, the intermediate layer may also have a partially mixed structure in which some of the fibers are melted by the heat of the molten skin layer (corresponding to an intermediate layer having both the structures of a and c above). (Sound-absorbing structure obtained by method b) The sound-absorbing structure obtained by method b above has an intermediate layer in which the fibers on the surface of the nonwoven fabric before lamination are welded to the surface of the skin layer. At this time, a thin layer of molten nonwoven fabric fibers is integrally formed on the surface of the skin layer. Even in the sound-absorbing structure obtained by method b, the intermediate layer may have a partially mixed structure (corresponding to an intermediate layer having both the structures of (a) and (c) above) due to the heat of the molten fibers melting some of the skin layer as well. (Sound-absorbing structure obtained by method c) The sound-absorbing structure obtained by method c above has an intermediate layer formed by melting and mixing the surface fibers of the nonwoven fabric before lamination with the resin of the skin layer.

[0045] (Laminates not included in the sound-absorbing structure of the present invention) The sound-absorbing structure of the present invention has the above structure obtained by the above method. Therefore, the laminate does not include a layer directly provided on at least one surface of the hollow plate material that consists solely of a nonwoven fabric layer or a layer composed solely of resin and nonwoven fabric throughout its entire thickness. Naturally, this does not include laminates formed by laminating nonwoven fabric and a base material, then heating and compressing them using a mold, etc., to heat the side of the nonwoven fabric that is not the base material side and melt at least some of its components, or laminates having a structure consisting of a layer formed by heating the entire thickness of the nonwoven fabric and melting at least some of its components, and a base material. This does not include a laminate in which some of the surface fibers of the nonwoven fabric, which are in point contact with the surface of the skin layer, are in point contact with the skin layer and / or the fibers of the nonwoven fabric once they have been melted. It does not include a laminate formed by laminating a nonwoven fabric on the surface of a skin layer via an adhesive or tack layer. Furthermore, the layers provided on at least one surface of the hollow plate material include, in order, the skin layer, the intermediate layer, and the nonwoven fabric layer.

[0046] When installing the laminate of the present invention, for example, on the interior surface of a car's ceiling or door, the laminate is processed by bending it to conform to the non-flat shape of the interior surface of the ceiling or door. Furthermore, since the present invention involves laminating a nonwoven fabric so as to be directly fixed to the skin layer, even if the laminate is bent to achieve the aforementioned inner surface shape, the skin layer and the nonwoven fabric layer remain integrated and do not peel off from each other. Therefore, the sound absorption performance can be achieved as designed at any position within the laminate. In this invention, a portion of the holes formed in the upper and / or lower walls of the hollow plate material may or may not be sealed by a skin layer. Furthermore, in this invention, the skin layer and the nonwoven fabric layer are not integrated with a hot melt adhesive. [Examples]

[0047] Sample 1 was prepared as described below (corresponding to the case of Patent Document 1 mentioned above). The material consists of a core layer, which is a hollow plate material formed from a 0.3 mm thick polypropylene resin sheet with multiple cells arranged side by side, and skin layers of 0.3 mm thick polypropylene resin sheets bonded to both sides, with an overall plate thickness of 20 mm. The pitch between the centers of adjacent cells is 10.0 mm (average pitch P1 = 10.0 mm). One side of the sample (closed wall) has a communication hole with a diameter of approximately 1.2 mm that connects the inside and outside of the cells. The spacing between adjacent communication holes in the direction in which the cells are arranged in parallel is 8.0 mm (spacing P2 = 8.0 mm). The opening edge of the communication hole formed in the closed wall of the cell is located in the internal space of the cell.

[0048] Sample 1 above has dimensions of 910 x 1820 mm (1.66 m). 2 Cut it so that it becomes 24.82 m³ 3The reverberation chamber method sound absorption coefficient was measured in a reverberation chamber. The reverberation chamber method sound absorption coefficient was measured at frequencies of 315Hz, 400Hz, 500Hz, 630Hz, 800Hz, 1000Hz, 1250Hz, 1600Hz, 2000Hz, 2500Hz, 3150Hz, 4000Hz, and 5000Hz, and the results are shown in Table 1. Except for the length and width dimensions of the sample and the volume of the reverberation chamber, the conditions followed the measurement method for reverberation chamber method sound absorption coefficient in JIS A1409.

[0049] Sample 2 was prepared as described below (corresponding to the case of intermediate layer A in the present invention). After heating only the surface of the skin layer of sample 1 to slightly melt it, a solid polyester nonwoven fabric (3.0 mm thick) was quickly laminated to form an intermediate layer A, which was integrated with the surface of the skin layer by embedding the fiber ends of the polyester nonwoven fabric. The sound absorption coefficient was measured using the reverberation chamber method in the same manner as for sample 1, and the results are shown in Table 1.

[0050] Sample 3 was prepared as described below (corresponding to the case of intermediate layer A in the present invention). A solid polypropylene nonwoven fabric (3.0 mm thick) with only one side of its surface melted was attached to the unheated surface of the skin layer of Sample 1, thereby integrating the intermediate layer A, formed from the fiber ends of the polypropylene nonwoven fabric, with the nonwoven fabric layer connected to the intermediate layer on the surface of the skin layer. The sound absorption coefficient was measured using the reverberation chamber method in the same manner as for Sample 1, and the results are shown in Table 1.

[0051] Sample 4 was prepared as described below (corresponding to the case of intermediate layer U in the present invention). After heating only the surface of the skin layer of sample 1 to slightly melt it, a solid polypropylene nonwoven fabric (3.0 mm thick) was quickly laminated to form an intermediate layer C, which was created by making the melted skin layer surface and the skin layer side surface of the polypropylene nonwoven fabric compatible and integrating them. Outside of intermediate layer C, there is a nonwoven fabric layer consisting of a layer that is not the skin layer side of the polypropylene nonwoven fabric. The sound absorption coefficient was measured using the reverberation chamber method in the same manner as for sample 1, and the results are shown in Table 1.

[0052] Sample 5 was prepared as described below. A solid polypropylene nonwoven fabric (3.0 mm thick) was laminated to the surface of the skin layer of sample 1 using a polyolefin hot-melt adhesive. The sound absorption coefficient was measured using the reverberation chamber method in the same manner as for sample 1, and the results are shown in Table 1.

[0053] Table 1 shows that sample 1 exhibits reasonable sound absorption performance in the frequency range of 630 to 1600 Hz. In particular, in the frequency range of 800 to 1000 Hz, which includes human speech, it showed a high reverberation chamber sound absorption coefficient of 0.8 or higher. However, the sound absorption coefficient decreases as the frequency increases.

[0054] [Table 1]

[0055] Sample 1, which lacks a nonwoven fabric layer, does not achieve sufficient sound absorption, especially in the high-frequency range. Similarly, Sample 5, in which the nonwoven fabric is bonded to the skin layer with an adhesive, still does not achieve sufficient sound absorption in the high-frequency range. These results are also observed when the nonwoven fabric is heat-fused to the skin layer in point contact (i.e., without a specific intermediate layer). In contrast, according to Samples 2, 3, and 4, which are examples in accordance with the present invention, high sound absorption coefficients can be obtained even at frequencies of 1600 Hz and 2000 Hz, and in addition, even higher sound absorption coefficients can be achieved in the frequency range of 2500 Hz and above. As a result, according to the present invention, high sound absorption coefficients can be achieved in a wider frequency range, including the range of 600 Hz and 2000 Hz. In other words, the present invention does not simply involve heat-sealing a nonwoven fabric to the surface of a skin layer, but rather, by selecting to form a specific type of intermediate layer, it exhibits a remarkable effect compared to cases where this is not done. [Industrial applicability]

[0056] The sound-absorbing structure of the present invention can be installed in applications where sound absorption is required, such as inside automobiles or on the interior walls of buildings. [Explanation of Symbols]

[0057] S...Cell, S1...First cell, S2...Second cell, 10...Sound-absorbing structure, 15...Hole, 15a...First hole, 20...Core layer (hollow plate material), 21...Upper wall, 22...Lower wall, 23...Side wall, 30...Skin layer, 40...Skin layer

Claims

1. The structure comprises side walls that are erected in the thickness direction to partition the cells, and upper and lower walls provided at the edges of the side walls, with multiple openings formed in one of the upper and lower walls, and a skin layer made of a film-like material with smooth surfaces on both sides is laminated on the main surface of the hollow plate material in which multiple cells are arranged side by side, and the surface of the skin layer and a resin with a density of 5 to 200 mg / cm³ ３ The sound-absorbing structure has a nonwoven fabric layer with a thickness of 0.5 to 20.0 mm, which is welded to an intermediate layer having one or more of the structures described in A to C below. A: An intermediate layer in which some of the fibers of the nonwoven fabric layer are embedded within the skin layer while maintaining their fiber shape. (i): An intermediate layer having a structure in which some of the fibers of the nonwoven fabric layer are temporarily melted and adhered to the surface of the skin layer. (c) An intermediate layer having a structure in which the surface of the skin layer and some of the fibers of the nonwoven fabric layer are both melted and then mixed together.

2. The sound-absorbing structure according to claim 1, wherein a plurality of holes are formed in the skin layer.

3. The sound-absorbing structure according to claim 2, wherein, as the distribution of inner diameters of holes on the nonwoven fabric layer side of the skin layer provided on one wall portion, when the average value of the inner diameter is set to 100, 30% to 70% of the total number of holes have an inner diameter of 80% to 120% of the average value of the inner diameter.

4. A. It comprises side wall portions erected in the thickness direction to partition the cells, and upper and lower wall portions provided at the edges of the side wall portions, The upper wall portion and one of the lower wall portions have a structure in which a plurality of openings are formed, and the skin layer surface, which is made of a film-like material with smooth surfaces on both sides, is laminated on the main surface of the hollow plate material in which a plurality of cells are arranged side by side. and / or, On the skin layer side of the nonwoven fabric layer made of resin fibers, The process of heating, B. A step of pressing the surface of the skin layer and the skin layer side of the nonwoven fabric layer together. It has the following in order: The skin layer is laminated onto the main surface of a hollow plate material in which multiple cells are arranged side by side, and the surface of the skin layer is made of resin with a density of 5 to 200 mg / cm³. ３ A method for manufacturing a sound-absorbing structure having a nonwoven fabric layer with a thickness of 0.5 to 20.0 mm, welded together via an intermediate layer having one or more of the structures described in A to C below. A: An intermediate layer in which some of the fibers of the nonwoven fabric layer are embedded within the skin layer while maintaining their fiber shape. (i): An intermediate layer having only a structure in which some of the fibers of the nonwoven fabric layer have melted and adhered to the surface of the skin layer. U: An intermediate layer having a structure in which the surface of the skin layer and some of the fibers of the nonwoven fabric layer are both melted and then mixed together.

5. C. A step of heating the surface of a skin layer made of a film-like material with smooth surfaces on both sides, and / or the skin layer side of a nonwoven fabric layer made of resin fibers. D. A step of obtaining a laminate via an intermediate layer having one or more of the structures described in A to C below, formed by pressing the surface of the skin layer and the skin layer side of the nonwoven fabric layer together. E. The skin layer side surface of the obtained laminate, It comprises side wall portions erected in the thickness direction to partition cells, and upper and lower wall portions provided at the edges of the side wall portions, The structure comprises side walls that are erected in the thickness direction to partition the cells, and upper and lower walls provided at the edges of the side walls, with multiple openings formed in one of the upper and lower walls, and the main surface of the hollow plate material on which multiple cells are arranged side by side, The process of lamination, Contains A skin layer is laminated onto the main surface of a hollow plate material in which multiple cells are arranged side by side, and the surface of the skin layer is made of resin fibers with a density of 5 to 200 mg / cm³. ３ A method for manufacturing a sound-absorbing structure having a nonwoven fabric layer with a thickness of 0.5 to 20.0 mm that is welded to it. A: An intermediate layer in which some of the fibers of the nonwoven fabric layer are embedded within the skin layer while maintaining their fiber shape. (i): An intermediate layer having only a structure in which some of the fibers of the nonwoven fabric layer have melted and adhered to the surface of the skin layer. U: An intermediate layer having a structure in which the surface of the skin layer and some of the fibers of the nonwoven fabric layer are both melted and then mixed together.

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