Sound insulation components and how they are manufactured.

Abstract

Invention details;

Description

Soundproofing material and its manufacturing method

[0001] The present invention relates to a soundproofing material that is arranged at a distance from a sound source or at least partly in close contact with the sound source, and a method for manufacturing the same.

[0002] To reduce noise in the vehicle cabin, soundproofing materials are placed around the engine, which is a source of noise, and on the dash panel separating the engine compartment from the passenger compartment. Examples of soundproofing materials placed on dash panels include those made of fiber materials such as felt, and foams such as polyethylene foam and polyurethane foam. Patent Document 1 (JP-A-2003-125999) describes a molded polyurethane foam soundproofing material that can be effectively placed on a dash panel with a complex surface shape.

[0003] Japan Utility Model Publication No. 1-93153

[0004] Conventional polyurethane foam soundproofing materials have been treated to enhance sound insulation by impregnating the polyurethane foam with asphalt (tar) or the like, providing an integral skin layer, or laminating a surface layer made of polyvinyl chloride, rubber, or the like, which has a higher specific gravity than the polyurethane foam. However, while these treatments on polyurethane foam have a certain effect in improving sound insulation and reducing noise, they have the problem of increasing the weight of the soundproofing material itself. In recent vehicles, there is a strong demand for weight reduction to improve fuel efficiency as well as quieting the passenger compartment, making the use of such soundproofing materials undesirable. The present invention has been made in consideration of the above-mentioned points and aims to provide a soundproofing material made of polyurethane foam with excellent sound insulation properties and a method for manufacturing the same.

[0005] (1) The soundproofing material of the present invention is made of polyurethane foam and is placed at a distance from a sound source or with at least a portion of the foam in close contact with the sound source, and is characterized in that the polyurethane foam has a surface layer on at least a portion of its surface, and at least one surface of the polyurethane foam facing the sound source has at least an open-cell surface layer or core, and at least the surface layer of the other surface opposite the one surface is a closed-cell surface layer.

[0006] (2) In the above (1), the air permeability of the surface layer in the closed cell state (JIS K 6400-7 B method: 2012 / ISO 7231: 2010) is 3 ml / cm ２ It is preferable that the ratio is 1 / s or less.

[0007] (3) In the above (1) or (2), it is preferable that the average thickness of the surface layer in the closed cell state is 3 μm or more.

[0008] (4) In any of (1) to (3) above, it is preferable that the soundproofing material is positioned away from the sound source and is positioned in at least a portion of the non-sound source side of a partition material that separates the space into a sound source side space where the sound source is located and a non-sound source side space, so that the partition material and the one side surface of the polyurethane foam are directly opposite each other.

[0009] (5) In the above (4), it is preferable that the soundproofing material is used in a space formed by components that form a non-sound source side space, with the outer periphery of the polyurethane foam and the components being in close contact with each other.

[0010] (6) In the above (5), it is preferable that the outer periphery of the polyurethane foam substantially matches the shape of the component that forms the non-sound source side space.

[0011] (7) In the above (5) or (6), it is preferable that the size of the outer periphery of the polyurethane foam is larger than the space formed by the components that form the non-sound source side space.

[0012] (8) In any of (4) to (7) above, it is preferable that the shape of the surface of the partition material on the non-sound source side approximately matches the shape of at least a portion of the one side surface of the polyurethane foam.

[0013] (9) In any of the above (4) to (8), it is preferable that the soundproofing material has a closed space between the partition material and the one side surface of the polyurethane foam.

[0014] (10) In any one of (1) to (3) above, it is preferable that the soundproofing material is disposed at a distance from the sound source and covers at least a portion of the sound source.

[0015] (11) In any one of (1) to (3) above, it is preferable that the soundproofing material is arranged so that at least a portion thereof is in close contact with the sound source, and covers at least a portion of the sound source.

[0016] (12) In the above (11), it is preferable that the soundproofing material has a closed space between the sound source and the one side surface of the polyurethane foam.

[0017] (13) In any of the above (10) to (12), it is preferable that the soundproofing material has a shape that is approximately the same as that of the sound source and at least a part of the one side surface of the polyurethane foam.

[0018] (14) In any of the above (1) to (13), it is preferable that the surface layers of all surfaces adjacent to the one side surface of the polyurethane foam are closed-cell surface layers.

[0019] (15) A method for producing a soundproofing material according to the present invention comprises applying a release agent to the surface of a mold, injecting polyurethane foam raw material into the mold, and foaming the material to produce a soundproofing material made of polyurethane foam having a surface layer on its surface, wherein the soundproofing material is positioned away from a sound source or with at least a portion of the soundproofing material in close contact with the sound source, and wherein a release agent containing at least a linear hydrocarbon wax is applied to the mold surface forming at least one side surface of the polyurethane foam facing the sound source, and a release agent containing a branched hydrocarbon wax is applied to the mold surface forming at least the other side surface of the polyurethane foam opposite the one side surface, and an open-cell surface layer is formed on at least a portion of the one side surface of the polyurethane foam using the mold surface applied with the release agent containing at least the linear hydrocarbon wax, and a closed-cell surface layer is formed on the other side surface of the polyurethane foam opposite the one side surface using the mold surface applied with the release agent containing the branched hydrocarbon wax.

[0020] According to the present invention, the polyurethane foam, which is placed at a distance from the sound source or at least partially in close contact with the sound source, has a surface layer on at least a portion thereof, and at least one surface facing the sound source has at least an open-cell surface layer or core, and at least the other surface opposite the one surface has a closed-cell surface layer, thereby achieving good sound insulation.

[0021] 1 is a cross-sectional view of an embodiment of a soundproofing material. FIG. 1 is a schematic view of a vehicle viewed from the left side and a cross-sectional view taken along line A-A. FIG. 2 is a cross-sectional view of a modified example of a soundproofing material having a closed space in one embodiment of the soundproofing material, and a cross-sectional view of the soundproofing material arranged at a distance from the sound source. FIG. 1 is a cross-sectional view of a soundproofing material in close contact with a sound source in another embodiment of the soundproofing material, and a cross-sectional view of a soundproofing material having a closed space with a portion of the sound source in close contact with the sound source. FIG. 2 is a cross-sectional view showing a step of applying a release agent in an example of a method for manufacturing a soundproofing material. FIG. 3 is a cross-sectional view showing a step of injecting polyurethane foam raw materials in an example of a method for manufacturing a soundproofing material. FIG. 4 is a cross-sectional view showing a foaming step in an example of a method for manufacturing a soundproofing material. FIG. 5 is a cross-sectional view showing a demolding step in an example of a method for manufacturing a soundproofing material. FIG. 6 is a table showing the formulations and measurement results of examples and comparative examples. FIG. 7 is a schematic view of photographs taken at 300x magnification of the vicinity of a surface layer in a closed-cell state and the vicinity of a surface layer in an open-cell state.

[0022] An embodiment of the soundproofing material of the present invention will be described with reference to the drawings. The soundproofing material 10 shown in FIG. 1 is disposed on at least a portion of the cabin-facing surface of a dash panel 50, which separates the space between an engine compartment (where an engine E (sound source) is located) and the passenger compartment. The soundproofing material 10 is composed of polyurethane foam 11 and has a surface layer 12 over its entire surface. At least one surface of the polyurethane foam 11 facing the passenger compartment-facing surface of the dash panel 50 has an open-cell surface layer 12A, and at least one surface of the polyurethane foam 11 opposite the open-cell surface (i.e., the passenger compartment-facing surface layer 12B) has a closed-cell surface layer. In the soundproofing material 10 of this embodiment, the surface layer 12 is formed substantially uniformly over the entire surface of the soundproofing material 10. In particular, if a portion of the closed-cell surface layer 12B has a highly breathable region, sound insulation performance will be significantly reduced. Therefore, it is preferable that the closed-cell surface layer 12B be formed uniformly over the entire passenger compartment-facing surface of the soundproofing material 10. The surface layer 12 on the outer periphery (side surface) of the polyurethane foam 11 may be either an open-cell surface layer or a closed-cell surface layer.

[0023] The surface layer 12 is a layered portion on the surface of the polyurethane foam 11 that has a higher density than the interior (core) of the polyurethane foam 11, and is formed by contact with the mold surface during foam molding of the polyurethane foam 11. The core is a portion that constitutes the interior of the polyurethane foam 11 and does not have the surface layer 12.

[0024] 2 (2-1), (2-2) and 3 (3-1), (3-2) will be used to explain the arrangement of the soundproofing material 10 in a vehicle according to one embodiment. The soundproofing material 10 is preferably arranged over the entire passenger compartment surface of the dash panel 50 in close contact with each of the left side component 51, right side component 52, and lower side component 57, which are components that form the non-sound source side space, without any gaps. The soundproofing material 10 can be fixed to the dash panel 50 using fasteners such as bolts and clips.

[0025] The outer periphery (right side, left side, lower side) of the soundproofing material 10, which is in close contact with the components (51, 52, 57) that form the non-sound source side space (vehicle cabin), is shaped to match the shape of the components (51, 52, 57) that form the non-sound source side space (vehicle cabin), and is approximately the same as the shape of the components (51, 52, 57).

[0026] In this way, the outer periphery of the soundproofing material 10 roughly matches the shape of the space formed by the components that make up the non-sound source side space (vehicle interior), and is positioned closely and without gaps to the shape of the space formed by the components, so that sound generated on the sound source side can be blocked across the entire surface of the dash panel 50.

[0027] Furthermore, the size of the soundproofing material 10 is the same as or larger than the shape of the space formed by the components that make up the non-sound source space (vehicle cabin). If the size of the soundproofing material 10 is larger than the shape of the space formed by the components, after the soundproofing material 10 is placed in the shape of the space formed by the components, the repulsive force of the polyurethane foam 11 that makes up the soundproofing material 10 acts in a direction that pushes the components, thereby improving adhesion to the components and further improving sound insulation. The size of the soundproofing material 10 is set appropriately depending on the characteristic values ​​of the soundproofing material 10 (mechanical properties such as density) and the shape of the space formed by the components, but is preferably 0 to 5% larger, and more preferably 0 to 2% larger, than the shape of the space formed by the components. If the size of the soundproofing material 10 exceeds 5%, it becomes difficult to place the soundproofing material 10 in the space formed by the constituent materials, and it may take a long time to assemble the soundproofing material 10, and there is a risk of damage (tears, etc.) occurring when placing the soundproofing material 10. Note that the soundproofing material 10 in this embodiment is set to be 0.5% larger than the shape of the space formed by the constituent materials.

[0028] The soundproofing material 10 is configured so that the shape of the passenger compartment-facing surface of the dash panel 50 substantially matches the shape of at least a portion of one side surface of the polyurethane foam 11. Therefore, even if vibrations occur while the vehicle is running, the dash panel 50 and the soundproofing material 10 do not rub against each other, and noise caused by rubbing between the dash panel 50 and the soundproofing material 10 can be prevented.

[0029] In one embodiment, the soundproofing material 10 is disposed over the entire surface of the dash panel 50 facing the passenger compartment, but the soundproofing material 10 may be disposed over only a portion of the surface. The soundproofing material 10 may be formed from a single component or a combination of two or more components.

[0030] In one embodiment, one side surface of the polyurethane foam 11 is composed only of an open-cell surface layer 12A, but it may also be composed of an open-cell surface layer 12A and a core, or it may be composed of a core only, or it may even have a closed-cell surface layer 12B on a portion of one side surface.

[0031] A modified example of an embodiment of the soundproofing material of the present invention will be described with reference to the drawings. The soundproofing material 10 shown in Figures 4 (4-1) and (4-2) is disposed on a dash panel 50 spaced from a vehicle engine E (a sound source). One or more recesses are formed in one side surface of the polyurethane foam 11 constituting the soundproofing material 10, and a closed space S is formed between the dash panel 50 and the soundproofing material 10. The closed space S between the dash panel 50 and the soundproofing material 10 reduces the propagation of structure-borne sound generated by the engine E between the dash panel 50 and the soundproofing material 10, thereby improving sound insulation. Therefore, the closed space S need only be formed so that the dash panel 50 and one side surface of the polyurethane foam 11 do not come into contact with each other. To reduce the propagation of structure-borne sound, it is more preferable to increase the proportion of the closed space S that does not contact the dash panel 50 and one side surface of the polyurethane foam 11.

[0032] Furthermore, the distance between the dash panel 50 and one side surface of the polyurethane foam 11 that constitute the closed space S may be the same or different. Examples of different distances between the dash panel 50 and one side surface of the polyurethane foam 11 include a stepped shape, a semicircular shape, a triangular shape, and the like. The closed space S may also be formed by combining these shapes. On the other hand, since the soundproofing material 10 (polyurethane foam 11) has a greater attenuation effect on airborne sound than the air layer (closed space S), it is preferable to configure the closed space S so that the proportion of the soundproofing material 10 is greater.

[0033] The closed space S (recess) shown in Figures 4 (4-1) and (4-2) has an open-cell surface layer 12A formed by the shape of the mold, but the open-cell surface layer 12A formed by the shape of the mold may also be formed by post-processing such as cutting. When formed by post-processing such as cutting, one side surface of the polyurethane foam 11 will be composed of the open-cell surface layer 12A and the core. Even if a portion of one side surface of the polyurethane foam 11 is composed of the core, the breathability of the core is the same as or greater than that of the open-cell surface layer 12A, so the amount of sound entering the polyurethane foam 11 will be the same as or greater, and good sound insulation will be achieved.

[0034] The contact ratio (contact area between dash panel 50 and polyurethane foam 11) that constitutes closed space S is preferably 10 to 99%, more preferably 20 to 90%, and even more preferably 30 to 85%. By keeping the contact ratio between dash panel 50 and polyurethane foam 11 within the above range, the propagation of solid-borne sound between dash panel 50 and soundproofing material 10 is reduced, thereby improving sound insulation.

[0035] The soundproofing material 10 shown in FIG. 4 (4-3) is disposed at a distance from a duct D (sound source) of a vehicle and is disposed so as to cover the duct D on three sides. By covering the duct D with the soundproofing material 10, it is possible to improve sound insulation in a specific direction. In this embodiment, the soundproofing material 10 is disposed so as to cover the duct D on three sides. However, the soundproofing material 10 may be disposed so as to cover only one side (directly facing the duct D), two sides (facing the duct D in an L-shape), or all sides (covering the outer periphery of the duct D). The soundproofing material 10 may be fixed directly to the duct D and a portion of the soundproofing material 10 with fasteners such as bolts or clips, or may be fixed to another component (such as a hose or pipe) inside the engine E. The soundproofing material 10 may be formed as a single component, or may be formed by combining two or more components. The shape of one side surface of the polyurethane foam 11 of the soundproofing material 10 is configured so that at least a portion of the shape of the outer periphery of the duct D approximately matches. In Figure 4 (4-3), the duct D is formed in a rectangular shape, so part of one side surface of the polyurethane foam 11 is also formed in a rectangular shape and is approximately the same. If the duct D is circular, it is preferable to form part of one side surface of the polyurethane foam 11 in a semicircular shape. The distance between the duct D (sound source) and the soundproofing material 10 is set appropriately depending on the arrangement of piping, the space available for placing the soundproofing material 10, etc., but is preferably 2 to 40 mm.

[0036] Another embodiment of the soundproofing material of the present invention will be described with reference to the drawings. The soundproofing material 10 shown in FIG. 5 (5-1) is positioned so as to be in close contact with a portion of the outer peripheral surface of the engine E. The soundproofing material 10 is composed of polyurethane foam 11 and has a surface layer 12 over its entire surface. The surface layer 12A formed on one side surface of the polyurethane foam 11, which covers a portion of the outer peripheral surface of the engine E, has at least an open-cell surface layer, while the surface layer 12B on the other side surface opposite the one side surface (i.e., the surface opposite the engine E) has a closed-cell surface layer. The shape of one side surface of the polyurethane foam 11 of the soundproofing material 10 is configured so that at least a portion of the shape of the outer peripheral surface of the engine E substantially matches the shape of a portion of the outer peripheral surface of the engine E. In FIG. 5 (5-1), the shape of a portion of the outer peripheral surface of the engine E substantially matches the shape of a portion of the one side surface of the polyurethane foam 11. The soundproofing material 10 can be fixed using fasteners such as bolts or clips. The soundproofing material 10 may be composed of a single component or a combination of two or more components.

[0037] In another embodiment, one side surface of the polyurethane foam 11 is composed only of an open-cell surface layer 12A, but it may also be composed of an open-cell surface layer 12A and a core, or it may be composed of a core only, or it may even have a closed-cell surface layer 12B on a portion of one side surface.

[0038] The soundproofing material 10 shown in FIG. 5 (5-2) is disposed in close contact with a portion of the outer circumferential surface of the engine E, forming a closed space S between the engine E and the soundproofing material 10. Providing a closed space S between the engine E and the soundproofing material 10 reduces the propagation of structure-borne sound generated by the engine E to the soundproofing material 10, thereby improving sound insulation. In order to reduce the propagation of structure-borne sound, it is preferable to increase the proportion of the non-contact portion between the dash panel 50 and one side surface of the polyurethane foam 11 in the closed space S. At least a portion of the shape of one side surface of the polyurethane foam 11 of the soundproofing material 10 substantially coincides with the shape of the outer circumferential surface of the engine E. In FIG. 5 (5-2), the shape of a portion of the outer circumferential surface of the engine E and the shape of a portion of one side surface of the polyurethane foam 11 substantially coincide with each other. 5 (5-2) is formed so as to have an open-cell surface layer 12A due to the shape of the mold, but the open-cell surface layer 12A formed due to the shape of the mold may be formed by post-processing such as cutting. The distance between the engine E (sound source) and the soundproofing material 10 is set appropriately depending on the space available for arranging the soundproofing material 10, and is preferably 2 to 40 mm.

[0039] The surface layer 12 on the outer periphery (side surface) of the polyurethane foam 11 may be either an open-cell surface layer or a closed-cell surface layer, but is preferably a closed-cell surface layer. By forming the surface layer 12 on the outer periphery (side surface) of the polyurethane foam 11 as a closed-cell surface layer, noise generated by the engine E can be effectively insulated.

[0040] When the soundproofing material 10 is arranged so as to cover the entire surface of the sound source, it can extremely effectively block noise leaking from the sound source to the outside. On the other hand, even if it is not possible to cover the entire surface of the sound source with the soundproofing material 10 due to the shape of the sound source or the arrangement of hoses and pipes connected to the sound source, or if it is desired to reduce the number of parts, noise can be effectively blocked by partially arranging the soundproofing material 10 in areas where noise is particularly loud.

[0041] The engine E and duct D correspond to the sound source, the engine room corresponds to the sound source side space, the passenger compartment corresponds to the non-sound source side space, and the dash panel 50 corresponds to the partition that separates the space into the sound source side space and the non-sound source side space. The partition that separates the space into the engine room and the passenger compartment is not limited to the dash panel, and any partition that separates the space into the sound source side space and the non-sound source side space can be arranged and used.

[0042] The soundproofing material 10 in one embodiment of the present invention is made of polyurethane foam 11, and has a surface layer 12 on at least a portion of its surface as shown in Figures 1, 4, and 5. At least one surface of the polyurethane foam 11 facing the sound source has at least an open-cell surface layer 12A or core, and at least the other surface opposite the one surface (i.e., the opposite side to the sound source) has a closed-cell surface layer 12B.

[0043] The open-cell surface layer 12A refers to a surface layer having a cell count (JIS K6400-1:2004, Appendix 1 (Reference)) of 20 to 100 cells / 25 mm, more preferably 30 to 100 cells / 25 mm. The closed-cell surface layer 12B refers to a surface layer having a cell count (JIS K6400-1:2004, Appendix 1 (Reference)) of 0 to 18 cells / 25 mm, more preferably 0 to 3 cells / 25 mm, and even more preferably 0 to 1 cell / 25 mm. The core has a cell count (JIS K6400-1:2004, Appendix 1 (Reference)) of 20 to 100 cells / 25 mm, more preferably 30 to 100 cells / 25 mm.

[0044] The air permeability (JIS K6400-7 B method: 2012 / ISO 7231: 2010) of the surface layer 12A in the open cell state is greater than that of the surface layer 12B in the closed cell state. Specifically, the air permeability of the surface layer 12A in the open cell state is preferably 3 to 30 ml / cm. ２ / s, more preferably 5 to 30 ml / cm ２ / s, and the air permeability of the surface layer 12B in the closed cell state is 3 ml / cm ２ / s or less is preferred, and 1 ml / cm２ / s or less is more preferable, and 0.5 ml / cm ２ The air permeability of the interior (core) is 3 to 50 ml / cm ２ The air permeability of the open-cell surface layer 12A is preferably large because it is desired to take in sounds generated from as many sound sources as possible into the polyurethane foam 11 (to increase the amount of incident sound), while the air permeability of the closed-cell surface layer 12B is preferably small because it is desired to block as much as possible the sound that has entered the polyurethane foam 11 and is attempting to transmit toward the vehicle interior (to increase the amount of reflection of incident sound).

[0045] The thickness of the surface layer can be measured by measuring the distance between the surface of the surface layer and the top of the cells of the polyurethane foam 11. In the open-cell surface layer 12A, the cells of the surface layer are open (no surface layer is present), making it impossible or difficult to measure the thickness of the surface layer. On the other hand, in the closed-cell surface layer 12B, the average thickness of the surface layer is preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 8 μm or more. The upper limit of the average thickness of the closed-cell surface layer 12B is approximately 100 μm. By setting the average thickness of the surface layer within the above range, the air permeability of the surface layer can be reduced, resulting in improved sound insulation.

[0046] The polyurethane foam 11 has an overall density (JIS K7222:2005 / ISO 845:1988) of 80 to 300 kg / m 3 including the surface layer. ３ is preferred, and 85 to 250 kg / m ３ More preferably, 90 to 200 kg / m ３ The overall density is more preferably 80 kg / m ３ In the following cases, the sound insulation of the polyurethane foam 11 alone may be reduced, and the sound insulation may be reduced to 300 kg / m ３ In the above cases, it is not preferable for applications such as vehicles where weight reduction is required. The thickness of the polyurethane foam 11 is determined appropriately, and may be, for example, about 10 to 100 mm.

[0047] The soundproofing material 10 is manufactured by a known mold foaming method in which polyurethane foam raw material is injected into a mold and foamed. A manufacturing method for the soundproofing material 10 of one embodiment will be described with reference to Figures 6 to 9.

[0048] 6 to 9 is composed of a lower mold 61 and an upper mold 65. A mold surface 62 of the lower mold 61 is a mold surface that forms the surface of the soundproofing material 10 that faces the dash panel 50. On the other hand, a mold surface 66 of the upper mold 65 is a mold surface that forms the surface of the soundproofing material 10 that faces the passenger compartment. The mold 60 is heated to 40 to 80°C by a known heating method. The heating method is not limited to a specific method, and may include a method in which the mold 60 is placed in a heating furnace or a method in which piping through which a heating medium circulates is provided on the outer surfaces of the lower mold 61 and the upper mold 65.

[0049] As shown in Figure 6, a release agent W1 containing a linear hydrocarbon wax is applied to the entire surface of a mold surface 62 of a lower mold 61, which forms the surface of the soundproofing material 10 facing the dash panel 50, while a release agent W2 containing a branched hydrocarbon wax is applied to the entire surface of a mold surface 66 of an upper mold 65, which forms the surface of the soundproofing material 10 facing the passenger compartment. Examples of linear hydrocarbon waxes include paraffin wax, Fischer-Tropsch wax, and Sasol wax. These waxes can be solvent-based release agents dispersed in an organic solvent, or water-based release agents dispersed in water using an emulsifier. Examples of branched hydrocarbon waxes include microcrystalline wax and modified polyethylene wax, and these waxes can be solvent-based or water-based release agents.

[0050] In one embodiment, the release agent W1 is applied to the entire surface of the mold surface 62 of the lower mold 61, which forms the surface of the soundproofing material 10 facing the dash panel 50. However, after the release agent W1 is applied to the entire surface of the mold surface 62 of the lower mold 61, the release agent W2 may be applied to a portion of the mold surface 62 of the lower mold 61 in an overlapping manner, so that one surface of the polyurethane foam 11 of the soundproofing material 10 is composed of the open-cell surface layer 12A and the closed-cell surface layer 12B. It is preferable that the closed-cell surface layer 12B on one surface of the polyurethane foam 11 be limited to an area where sound insulation is required.

[0051] Since linear hydrocarbon waxes are composed of a main chain primarily consisting of linear hydrocarbons, they tend to have a lower proportion of terminal methyl groups and stronger polarity than branched-chain hydrocarbon waxes. Since branched-chain hydrocarbon waxes are composed primarily of branched-chain hydrocarbons, they tend to have a higher proportion of terminal methyl groups and weaker polarity. Therefore, the difference in polarity (solubility) between the polyurethane foam raw materials constituting the polyurethane foam described below and the linear hydrocarbon wax is relatively smaller than the difference in polarity (solubility) between the polyurethane foam raw materials and the branched-chain hydrocarbon wax. When a release agent W1 containing a linear hydrocarbon wax is used, a surface layer is less likely to form on the polyurethane foam surface, and the surface layer that is formed tends to be thin and open-celled. On the other hand, when a release agent W2 containing a branched-chain hydrocarbon wax is used, a surface layer is more likely to form on the polyurethane foam surface, and the surface layer that is formed tends to be thick and closed-celled. The release agent is applied by a known method, such as spraying or brushing, and the amount of release agent applied is 10 to 300 g / m. ２ is.

[0052] After the mold release agent is applied to the mold surface 62 of the lower mold 61 and the mold surface 66 of the upper mold 65, polyurethane foam raw material F is poured into the mold 60 as shown in Fig. 7. The polyurethane foam raw material F contains polyol, isocyanate, a blowing agent, a catalyst, and appropriate additives.

[0053] As the polyol, known ether polyols, ester polyols, ether ester polyols, polymer polyols, etc., which are used in the production of polyurethane foams, can be used alone or in combination.

[0054] Examples of ether polyols include polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, neopentyl glycol, glycerin, pentaerythritol, trimethylolpropane, sorbitol, and sucrose, 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, can also be used.

[0055] The isocyanate may be any of aromatic, alicyclic, and aliphatic isocyanates, and may be a bifunctional isocyanate having two isocyanate groups in one molecule, or a trifunctional or higher isocyanate having three or more isocyanate groups in one molecule, and these may be used alone or in combination.

[0056] For example, bifunctional isocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, xylylene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 3,3'-dimethoxy-4,4 Examples of the isocyanate include aromatic isocyanates such as cyclohexane-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, and methylcyclohexane diisocyanate; and aliphatic isocyanates such as butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, and lysine isocyanate.

[0057] Examples of tri- or higher functional isocyanates include 1-methylbenzene-2,4,6-triisocyanate, 1,3,5-trimethylbenzene-2,4,6-triisocyanate, biphenyl-2,4,4'-triisocyanate, diphenylmethane-2,4,4'-triisocyanate, methyldiphenylmethane-4,6,4'-triisocyanate, 4,4'-dimethyldiphenylmethane-2,2',5,5'tetraisocyanate, triphenylmethane-4,4',4"-triisocyanate, polymeric MDI, and the like. Polymers can also be used. Isocyanates may be used alone or in combination. For example, an aliphatic isocyanate and an aromatic isocyanate may be used in combination. The isocyanate index is preferably 90 to 115, more preferably 95 to 110. The isocyanate index is an index used in the polyurethane field, and is a numerical value that represents the equivalent ratio of isocyanate groups of isocyanate to active hydrogen groups in raw materials (e.g., active hydrogen groups contained in hydroxyl groups of polyols and active hydrogen groups of water, etc., used as a blowing agent), expressed as a percentage.

[0058] The blowing agent is not particularly limited, but water is preferred. Alternatively, carbon dioxide gas, pentane, hydrofluoroolefin (HFO), or the like may be used as a blowing aid in combination with the water blowing agent. HFOs are compounds with an ozone depletion potential (ODP) of 0 and a low global warming potential (GWP). The amount of water used as a blowing agent is preferably 0.3 to 3 parts by weight per 100 parts by weight of polyol.

[0059] The catalyst may be any known catalyst for polyurethane foams. Examples include amine catalysts such as triethylamine, triethylenediamine, diethanolamine, 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. The preferred amount of catalyst is generally 0.2 to 3 parts by weight per 100 parts by weight of polyol.

[0060] Additives that are appropriately blended include foam stabilizers, colorants, crosslinking agents, fillers, flame retardants, antioxidants, and other synthetic resin stabilizers. The foam stabilizer may be any foam stabilizer that is used in polyurethane foams, including silicone foam stabilizers, fluorine-containing compound foam stabilizers, and known surfactants. Colorants, such as pigments and dyes, are used depending on the desired color.

[0061] After the polyurethane foam raw material F is injected into the mold 60, the mold is closed as shown in Fig. 8, and a foaming reaction of the polyurethane foam raw material is carried out. Although the illustrated example shows an example in which the polyurethane foam raw material is injected while the mold 60 is open, an injection port (not shown) may be provided in the upper mold 65, and the polyurethane foam raw material F may be injected into the mold 60 through the injection port while the mold 60 is closed.

[0062] Soundproofing material 10 made of polyurethane foam 11 is formed in mold 60 by a foaming reaction of polyurethane foam raw material F. An open-cell surface layer is formed over the entire surface of polyurethane foam 11 on the surface formed by mold surface 62 of lower mold 61 during foam molding, i.e., the surface of soundproofing material 10 facing dash panel 50, by mold release agent W1 containing a linear hydrocarbon wax that is applied to the entire surface of mold surface 62 of lower mold 61. On the other hand, a closed-cell surface layer is formed over the entire surface of polyurethane foam 11 on the surface formed by mold surface 66 of upper mold 65 during foam molding, i.e., the surface of soundproofing material 10 facing the passenger compartment (the surface opposite dash panel 50) by mold release agent W2 containing a branched-chain hydrocarbon wax that is applied to the entire surface of mold surface 66 of upper mold 65.

[0063] Thereafter, the mold 60 is opened as shown in Fig. 9, and the soundproofing material 10 made of the polyurethane foam 11 is removed. The soundproofing material 10 removed from the mold 60 has at least an open-cell surface layer 12A on one surface of the polyurethane foam 11 that faces the interior-side surface of the dash panel 50, and a closed-cell surface layer 12B on the other surface opposite the one surface, as shown in Fig. 1.

[0064] Examples and comparative examples of the present invention are described below. Using polyurethane foam raw materials with the formulation shown in Figure 10, soundproofing materials (test pieces) made of polyurethane foam, each measuring 500 mm square x 25 mm thick (for measuring transmission loss) and 500 mm square x 30 mm thick (for measuring density, breathability, cell count, etc.), were manufactured by a mold foaming method. In Comparative Example 1, the soundproofing material was made of felt. The numerical values ​​for each component in the formulation shown in Figure 10 indicate parts by weight. The mold used was of the open mold type, in which the material is poured into the mold. The mold was heated with warm water, with the lower mold 61 fixed at 60°C and the upper mold 65 heated to 45 to 70°C.

[0065] Polyol: polyether polyol, number of functional groups: 3, weight average molecular weight: 5000, hydroxyl value: 35 mg KOH / g Blowing agent: water Amine catalyst 1: "DABCO 33LSI" manufactured by Air Products Japan Co., Ltd. Amine catalyst 2: "DABCO BL-19" manufactured by Air Products Japan Co., Ltd. Foam stabilizer: "SZ-1346E" manufactured by Dow Corning Toray Co., Ltd., silicone foam stabilizer Isocyanate: polymeric MDI, isocyanate group content (NCO%): 31.5% Mold release agent W1: "URM-520" manufactured by Konishi Co., Ltd., linear hydrocarbon wax Mold release agent W2: "N-915" manufactured by Chukyo Yushi Co., Ltd., branched hydrocarbon wax

[0066] In Examples 1 to 6, the release agent W1 (linear type) was used on the side facing the dash panel (the surface of the lower mold) and the release agent W2 (branched type) was used on the side facing the passenger compartment (the surface of the upper mold), and the amounts of foaming agent and isocyanate were varied. In Examples 1 to 6, the temperature of the lower mold 61 was 60°C, and in Examples 1 and 3, the temperature of the upper mold 65 was changed to 70°C and 45°C, respectively. In Examples 2 and 4 to 6, the temperature of the upper mold 65 was 60°C. In Examples 1 to 6, the release agent W1 was used on the entire surface 62 of the lower mold 61, and the release agent W2 was used on the entire surface 66 of the upper mold 65. However, both the release agent W1 and the release agent W2 may be used on the surface 62 of the lower mold 61.

[0067] Comparative Example 1 is a felt (manufactured by Fujiko Co., Ltd., material: wool, basis weight: 800 g / m ２ , thickness: 25 mm). Comparative Example 2 is an example in which the release agent W2 (branched-chain type) was used on both the side facing the dash panel (mold surface of the lower mold) and the side facing the passenger compartment (mold surface of the upper mold). Comparative Example 3 is an example in which the release agent W2 (branched-chain type) was used on the side facing the dash panel (mold surface of the lower mold) and the release agent W1 (straight-chain type) was used on the side facing the passenger compartment (mold surface of the upper mold), which is the opposite of Examples 1 to 6. Comparative Example 4 is an example in which the release agent W1 (straight-chain type) was used on both the dash panel side (mold surface of the lower mold) and the passenger compartment side (mold surface of the upper mold). Comparative Examples 2 to 4 are examples in which the temperatures of the lower mold 61 and the upper mold 65 were both 60°C.

[0068] For Examples 1 to 6 and Comparative Examples 2 to 4, the air permeability, surface layer structure (open cell or closed cell), surface layer thickness, transmission loss, density, and cell count were evaluated and measured for the side facing the dash panel, the passenger compartment side, and the core. The surface layer structure was judged based on the cell count, air permeability, and appearance (visual inspection). Note that for Comparative Example 1, only transmission loss was measured. The measurement results are shown in Figure 10. In the measurement results in Figure 10, the sound source side is the side facing the dash panel, while the non-sound source side is the passenger compartment side, and the core is inside the soundproofing material.

[0069] The thickness of the surface layer was measured using a scanning electron microscope (JEOL Ltd.: JSM-IT100). Specifically, a polyurethane foam having a surface layer cut to a predetermined shape was coated with platinum using a platinum deposition device (JEOL Ltd.: JEC-3000FC) to facilitate observation using a scanning electron microscope. Then, a photograph was taken of the vicinity of the surface layer at 300x magnification, and the distance between the surface (outermost surface) of the surface layer and the top of the cell was measured. The thickness of the surface layer was measured at six points in the photograph: the thickest thickness (L1), the second thickest thickness (L2), the third thickest thickness (L3), the thinnest thickness (S1), the second thinnest thickness (S2), and the third thinnest thickness (S3), and the average value was taken as the average thickness of the surface layer. Figure 11 (11-1) is a schematic diagram of a photograph taken at 300 times magnification of the vicinity of the surface layer in a closed-cell state, and Figure 11 (11-2) is a schematic diagram of a photograph taken at 300 times magnification of the vicinity of the surface layer in an open-cell state, in which the symbol 91 indicates the surface layer, 93 indicates the cell, and X indicates the distance between the surface of the surface layer 91 and the top of the cell 93.

[0070] The transmission loss was measured based on JIS A1441-1:2007 / ISO 15186-1:2000. The test specimen was prepared by placing a 500 mm square x 25 mm thick soundproofing material made of polyurethane foam having a surface layer on the entire surface (top, bottom, and side surfaces) of one side of a metal steel plate (size: 500 mm square x 1 mm thick) so that the open-cell surface layer or the closed-cell surface layer was in close contact with the metal steel plate, and fixing the four corners of the soundproofing material to the metal steel plate with bolts. The transmission loss was measured by treating the metal steel plate as the dash panel 50, irradiating sound from the metal steel plate side, and measuring the value at 1600 Hz.

[0071] The number of cells was measured by dividing a soundproofing material made of polyurethane foam measuring 500 mm square and 30 mm thick into three parts: the dash panel side, the passenger compartment side, and the core (interior).The number of cells was measured using a magnifying glass at 30x magnification on the side surface facing the dash panel (surface layer side), the divided surface of the core, and the passenger compartment side surface (surface layer side) in accordance with JIS K6400-1:2004 Appendix 1 (Reference).

[0072] To measure the breathability, a 500 mm square x 30 mm thick soundproofing material was divided into three parts: the dash panel side, the passenger compartment side, and the core (interior), and test pieces were prepared so that each part was 10 mm thick. The breathability was measured for the side facing the dash panel, the core, and the passenger compartment side, based on JIS K6400-7 Method B:2012 / ISO 7231:2010.

[0073] The density was measured for the overall density of a 500 mm square x 30 mm thick soundproofing material, and for the side facing the dash panel, the core, the passenger compartment side, and the entire soundproofing material, which was divided into three sections with a thickness of 10 mm: the side facing the dash panel, the core, the passenger compartment side, and the entire material, in accordance with JIS K7222:2005 / ISO 845:1988. The side facing the dash panel has a surface layer on the top and side surfaces, the passenger compartment side has a surface layer on the bottom and side surfaces, and the core has a surface layer on the side surfaces.

[0074] In Example 1, the air permeability was 21 ml / cm on the side facing the dash panel (sound source side). ２ / s, core 21 ml / cm ２ / s, and 1.2 ml / cm on the passenger compartment side (non-sound source side). ２ The surface layer on the side facing the dash panel (sound source side) was an open-cell surface layer, so the thickness of the surface layer could not be measured, while the surface layer on the passenger compartment side (non-sound source side) was a closed-cell surface layer with an average thickness of 7 μm. The transmission loss was 46 dB, and the contact ratio between the metal steel plate and the soundproofing material was 100%. The density of the side facing the dash panel (sound source side) was 131 kg / m ３ , core 127 kg / m ３ , 135 kg / m on the passenger compartment side (non-sound source side) ３, the whole is 130 kg / m ３ The number of cells was 59 cells / 25 mm on the side facing the dash panel (sound source side), 51 cells / 25 mm on the core, and 0 cells / 25 mm on the passenger compartment side (non-sound source side).

[0075] In Example 2, the air permeability was 20 ml / cm on the side facing the dash panel (sound source side). ２ / s, core 20 ml / cm ２ / s, and 0.7 ml / cm on the passenger compartment side (non-sound source side). ２ / s. The surface layer on the side facing the dash panel (sound source side) was an open-cell surface layer, so the thickness of the surface layer could not be measured, while the surface layer on the passenger compartment side (non-sound source side) was a closed-cell surface layer with an average thickness of 11 μm. The transmission loss was 48 dB, and the contact ratio between the metal steel plate and the soundproofing material was 100%. The density of the side facing the dash panel (sound source side) was 132 kg / m ３ , core 126 kg / m ３ , 136 kg / m on the passenger compartment side (non-sound source side) ３ , the whole is 130 kg / m ３ The number of cells was 59 cells / 25 mm on the side facing the dash panel (sound source side), 53 cells / 25 mm on the core, and 0 cells / 25 mm on the passenger compartment side (non-sound source side).

[0076] In Example 3, the air permeability was 19 ml / cm on the side facing the dash panel (sound source side). ２ / s, core 20 ml / cm ２ / s, and 0.2 ml / cm on the passenger compartment side (non-sound source side). ２ / s. The surface layer on the side facing the dash panel (sound source side) was an open-cell surface layer, so the thickness of the surface layer could not be measured, while the surface layer on the passenger compartment side (non-sound source side) was a closed-cell surface layer with an average thickness of 20 μm. The transmission loss was 51 dB, and the contact ratio between the metal steel plate and the soundproofing material was 100%. The density of the side facing the dash panel (sound source side) was 133 kg / m ３ , core 126 kg / m ３ , 137 kg / m on the passenger compartment side (non-sound source side) ３ , the whole is 130 kg / m ３The number of cells was 59 cells / 25 mm on the side facing the dash panel (sound source side), 55 cells / 25 mm on the core, and 0 cells / 25 mm on the passenger compartment side (non-sound source side).

[0077] In Example 4, the air permeability was 28 ml / cm on the side facing the dash panel (sound source side). ２ / s, core 31 ml / cm ２ / s, and 2.6 ml / cm on the passenger compartment side (non-sound source side). ２ The surface layer on the side facing the dash panel (sound source side) was an open-cell surface layer, so the thickness of the surface layer could not be measured, while the surface layer on the passenger compartment side (non-sound source side) was a closed-cell surface layer with an average thickness of 5 μm. The transmission loss was 50 dB, and the contact ratio between the metal steel plate and the soundproofing material was 100%. The density of the side facing the dash panel (sound source side) was 91 kg / m ３ , core 81 kg / m ３ , 92 kg / m on the passenger compartment side (non-sound source side) ３ , the whole is 90 kg / m ３ The number of cells was 59 / 25 mm on the side facing the dash panel (sound source side), 45 / 25 mm on the core side, and 0 / 25 mm on the passenger compartment side (non-sound source side). In Example 4, the overall density was 90 kg / m ３ It is so light that it reduces the solid-borne sound that propagates through the soundproofing material, and the overall density is 130 kg / m ３ It is believed that the transmission loss (sound insulation) was improved compared to Example 2.

[0078] In Example 5, the air permeability was 2.5 ml / cm on the side facing the dash panel (sound source side). ２ / s, core 3 ml / cm ２ / s, 0.3ml / cm on the passenger compartment side (non-sound source side) ２ The surface layer on the side facing the dash panel (sound source side) was an open-cell surface layer, so the thickness of the surface layer could not be measured, while the surface layer on the passenger compartment side (non-sound source side) was a closed-cell surface layer with an average thickness of 13 μm. The transmission loss was 46 dB, and the contact ratio between the metal steel plate and the soundproofing material was 100%. The density of the side facing the dash panel (sound source side) was 205 kg / m ３ , core 185 kg / m３ , 210 kg / m on the passenger compartment side (non-sound source side) ３ , the whole is 200 kg / m ３ The number of cells was 72 / 25 mm on the side facing the dash panel (sound source side), 69 / 25 mm on the core, and 0 / 25 mm on the passenger compartment side (non-sound source side).

[0079] In Example 6, the air permeability was 20 ml / cm on the side facing the dash panel (sound source side). ２ / s, core 20 ml / cm ２ / s, and 0.8 ml / cm on the passenger compartment side (non-sound source side). ２ / s. The surface layer on the side facing the dash panel (sound source side) was an open-cell surface layer, so the thickness of the surface layer could not be measured, while the surface layer on the passenger compartment side (non-sound source side) was a closed-cell surface layer with an average thickness of 11 μm. The transmission loss was measured while changing the contact ratio of the test piece (soundproofing material made of polyurethane foam) prepared for measuring the transmission loss. The transmission loss of Example 6-1 was 52 dB, and the contact ratio between the metal steel plate and the soundproofing material was 80%. The transmission loss of Example 6-2 was 53 dB, and the contact ratio between the metal steel plate and the soundproofing material was 60%. The transmission loss of Example 6-3 was 54 dB, and the contact ratio between the metal steel plate and the soundproofing material was 40%. The density of the side facing the dash panel (sound source side) was 132 kg / m ３ , core 126 kg / m ３ , 136 kg / m on the passenger compartment side (non-sound source side) ３ , the whole is 130 kg / m ３ The number of cells was 59 cells / 25 mm on the side facing the dash panel (sound source side), 53 cells / 25 mm for the core, and 0 cells / 25 mm on the passenger compartment side (non-sound source side). Note that Example 6 has a closed space between the dash panel and the soundproofing material, which reduces the propagation of structure-borne sound from the dash panel to the soundproofing material, and it is thought that this enabled it to achieve a higher transmission loss (sound insulation) than Example 2.

[0080] Comparative Example 1 (felt) had a transmission loss of 39 dB at 1600 Hz, and was inferior to Examples 1 to 6 in sound insulation.

[0081] In Comparative Example 2, the air permeability was 0.8 ml / cm on the side facing the dash panel (sound source side). ２ / s, core 18 ml / cm ２ / s, and 0.7 ml / cm on the passenger compartment side (non-sound source side). ２ / s. The surface layer on the side facing the dash panel (sound source side) was a closed-cell surface layer with an average thickness of 10 μm, and the surface layer on the passenger compartment side (non-sound source side) was a closed-cell surface layer with an average thickness of 11 μm. The transmission loss was 39 dB, and the contact ratio between the metal steel plate and the soundproofing material was 100%, resulting in inferior sound insulation compared to Examples 1 to 6. The density on the side facing the dash panel (sound source side) was 135 kg / m ３ , core 124 kg / m ３ , 137 kg / m on the passenger compartment side (non-sound source side) ３ , the whole is 130 kg / m ３ The number of cells was 0 cells / 25 mm on the side facing the dash panel (sound source side), 55 cells / 25 mm on the core, and 0 cells / 25 mm on the passenger compartment side (non-sound source side).

[0082] In Comparative Example 3, the air permeability was 0.7 ml / cm on the side facing the dash panel (sound source side). ２ / s, core 21 ml / cm ２ / s, and 18.6 ml / cm on the passenger compartment side (non-sound source side). ２ / s. The surface layer on the side facing the dash panel (sound source side) was a closed-cell surface layer with an average thickness of 10 μm, while the surface layer on the passenger compartment side (non-sound source side) was an open-cell surface layer, so the thickness of the surface layer could not be measured. The transmission loss was 36 dB, and the contact ratio between the metal steel plate and the soundproofing material was 100%, resulting in inferior sound insulation compared to Examples 1 to 6. The density on the side facing the dash panel (sound source side) was 137 kg / m ３ , core 126 kg / m ３ , 133 kg / m on the passenger compartment side (non-sound source side) ３ , the whole is 130 kg / m ３ The number of cells was 0 cells / 25 mm on the side facing the dash panel (sound source side), 55 cells / 25 mm on the core, and 59 cells / 25 mm on the passenger compartment side (non-sound source side).

[0083] In Comparative Example 4, the air permeability was 19 ml / cm on the side facing the dash panel (sound source side). ２ / s, core 19 ml / cm ２ / s, and 18 ml / cm on the passenger compartment side (non-sound source side). ２ / s. The surface layer on the side facing the dash panel (sound source side) was an open-cell surface layer, while the surface layer on the passenger compartment side (non-sound source side) was an open-cell surface layer, and the thickness of both surface layers was unmeasurable. The transmission loss was 43 dB, and the contact ratio between the metal steel plate and the soundproofing material was 100%, which meant that the sound insulation was inferior to Examples 1 to 6. The density on the side facing the dash panel (sound source side) was 132 kg / m ３ , core 126 kg / m ３ , 132 kg / m on the passenger compartment side (non-sound source side) ３ , the whole is 130 kg / m ３ The number of cells was 59 / 25mm on the side facing the dash panel (sound source side), 55 / 25mm on the core, and 59 / 25mm on the passenger compartment side (non-sound source side).

[0084] As described above, Examples 1 to 6 had a transmission loss of 46 to 54 dB, while Comparative Examples 1 to 4 had a transmission loss of 36 to 43 dB, and Examples 1 to 6 were superior in sound insulation to Comparative Examples 1 to 4.

[0085] In the examples of the present invention, soundproofing material 10 was produced by using release agent W1 on the entire surface of mold surface 62 of lower mold 61 and release agent W2 on the entire surface of mold surface 66 of upper mold 65. Alternatively, soundproofing material 10 may be produced by using release agent W2 on the entire surface of mold surface 62 of lower mold 61 and release agent W1 on the entire surface of mold surface 66 of upper mold 65. Even in this case, soundproofing material 10 can be produced by positioning open-cell surface layer 12A (one side surface of polyurethane foam 11) formed by using release agent W1 so that it faces the sound source.

[0086] Alternatively, soundproofing material 10 may be produced by applying release agent W2 to the entire surface of mold surface 62 of lower mold 61 and by applying both release agent W1 and release agent W2 to the entire surface of mold surface 66 of upper mold 65. In either case, soundproofing material 10 can be produced by positioning open-cell surface layer 12A (one side surface of polyurethane foam 11) formed by using release agent W1 so that it faces the sound source, thereby achieving suitable sound insulation.

[0087] In this way, the soundproofing material made of the polyurethane foam of the present invention is placed so as to be spaced apart from or at least partially in close contact with a sound source, and the polyurethane foam has a surface layer on at least a portion of its surface, at least one surface of the polyurethane foam facing the sound source having at least an open-cell surface layer or core, and at least the surface layer on the other surface opposite the one surface having a closed-cell surface layer, thereby achieving good sound insulation. Therefore, sound insulation can be improved without an excessively high density, and the material is suitable as a soundproofing material for vehicles, which require light weight.

[0088] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.

[0089] In addition, the soundproofing material of the present invention may have one or more recesses for forming a closed space between the partition material and one side surface of the polyurethane foam when the soundproofing material is placed on at least a portion of the non-sound source side of the partition material.

[0090] The soundproofing material according to the present invention may be arranged at a distance from a sound source and may be arranged to cover at least a portion of the sound source.

[0091] The soundproofing material according to the present invention may be arranged so that at least a portion thereof is in close contact with a sound source and so as to cover at least a portion of the sound source.

[0092] In addition, the soundproofing material of the present invention may have one or more recesses for forming a closed space between the sound source and one side surface of the polyurethane foam when placed so that at least a portion of it is in close contact with the sound source.

[0093] This application is based on a Japanese patent application filed on March 23, 2017 (Patent Application No. 2017-057166) and a Japanese patent application filed on March 13, 2018 (Patent Application No. 2018-045372), both of which are incorporated by reference in their entireties. All references cited herein are incorporated by reference in their entireties.

[0094] DESCRIPTION OF SYMBOLS 10: Soundproofing material 11: Polyurethane foam 12: Surface layer 12A: Open-cell surface layer 12B: Closed-cell surface layer 50: Dash panel 50A: Interior-side surface of dash panel 60: Mold 61: Lower mold 62: Mold surface of lower mold 65: Upper mold 66: Mold surface of upper mold E: Engine D: Duct W1: Mold release agent containing linear hydrocarbon wax W2: Mold release agent containing branched hydrocarbon wax

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