Polyurethane molded body and sound-absorbing material

Abstract

[Problem] To provide a sound-absorbing material and a polyurethane molded body having a sound-absorbing effect. [Solution] A polyurethane molded body 1 comprises: polyurethane pieces 2; a joint part 3 at which a plurality of the polyurethane pieces 2 that are adjacent are joined to each other; and a communication hole 4. The respective pieces 2 are molded such that at least some of the pieces 2 are bent, and at least some of the pieces 2 have an end part 5 that is separated from an adjacent piece 2. A polyurethane molded body 1a of a first embodiment is such that a polyurethane piece has been passed through a sieve having 2 mm openings in advance. In contrast, a polyurethane molded body 1b of a second embodiment is such that a polyurethane piece has not passed through a sieve having 2 mm openings in advance.

Description

[Technical Field]

[0001] This invention relates to a sound-absorbing polyurethane molded article and a sound-absorbing material. [Background technology]

[0002] Conventionally, polyurethane molded articles have been proposed for use as sound-absorbing and / or heat-insulating materials in buildings and the like. For example, according to Patent Document 1, the following porous slab has been proposed. The porous slab has a density of 30-200 kg / m 3 Preferably 50-130 kg / m 3 It is made from crushed rigid polyurethane foam having a bulk density of at least 2 mm, preferably at least 5 mm, particularly preferably 5 to 20 mm, and an adhesive content of 3 to 25% by weight, preferably 5 to 12% by weight, and bonded with an adhesive.

[0003] According to this, it is stated that porous slabs can be provided for a wide range of applications, such as being used as a support in packaging, or as an insulating partition between a refrigerator and a freezer compartment. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 8-258160 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, the conventional example shown in Patent Document 1 has the following problems. According to Patent Document 1, the rigid polyurethane foam used is crushed and has an average particle size of 5 to 20 mm, particularly preferably with an adhesive content of 3 to 25% by weight, preferably 5 to 12% by weight. Since the average particle size of the crushed rigid polyurethane foam is of the above constant size, it is assumed that a large proportion of the cell structure is maintained without being destroyed. The cell structure of the rigid polyurethane foam has closed cells, so each cell has an independent structure, and in this case, it is assumed that a large proportion of adjacent cells are not in communication with each other. Consequently, there is a problem that the sound absorption effect is limited to a certain range and does not exhibit sufficient sound absorption effect.

[0006] The present invention aims to solve the problems of the prior art and to provide a polyurethane molded article and a sound-absorbing material that have sound-absorbing properties. [Means for solving the problem]

[0007] A polyurethane molded article according to a first aspect of the present invention comprises a polyurethane fragment, a bonding portion connecting a plurality of adjacent fragments to each other, and a communication hole, wherein the fragment is molded in such a state that at least a portion is bent and at least a portion has an end that is separated from adjacent fragments.

[0008] According to this, the polyurethane molded body has breathability because it is equipped with fragments, joints, and communication holes. Furthermore, the fragments are joined to each other at the joints, and at least a portion of them is in a refracted state, and at least a portion of them has ends that are separated from adjacent fragments. Therefore, the polyurethane molded body attenuates sound vibrations and exhibits a sound-absorbing effect.

[0009] Furthermore, the polyurethane molded body may be made from fragments that have previously passed through a sieve with a mesh size of 2 mm. In this case, since the polyurethane fragments have previously passed through a sieve with a mesh size of 2 mm, the density after compression molding is high, and the fragments, joints, and communication holes are formed more uniformly. Therefore, a stable sound absorption effect is achieved.

[0010] Furthermore, the polyurethane molded body may be made from fragments that have not passed through a sieve with a mesh size of 2 mm beforehand. In this case, since the polyurethane fragments have not passed through a sieve with a mesh size of 2 mm beforehand, the density after compression molding is low, making weight reduction possible. In addition, the sound absorption effect can be further enhanced.

[0011] A sound-absorbing material according to a second aspect of the present invention comprises the polyurethane molded body. This provides a sound-absorbing material with a high sound-absorbing effect because it comprises a polyurethane molded body having sound-absorbing properties.

[0012] Furthermore, the polyurethane molded article may have a normal incidence sound absorption coefficient of 50% or more in the frequency range from 400 Hz to 6500 Hz. In this case, the sound-absorbing material exhibits a sound-absorbing effect in a wide frequency range from 400 Hz to 6500 Hz.

[0013] Furthermore, the polyurethane molded article may have a normal incidence sound absorption coefficient of 55% or more in the frequency range from 700 Hz to 6500 Hz. In this case, the sound-absorbing material will exhibit a greater sound absorption effect in the frequency range from 700 Hz to 6500 Hz.

[0014] Furthermore, the polyurethane molded article may have a normal incidence sound absorption coefficient of 60% or more in the frequency range from 2000 Hz to 6500 Hz. In this case, the sound-absorbing material exhibits an even greater sound-absorbing effect in the frequency range from 2000 Hz to 6500 Hz.

[0015] Furthermore, the polyurethane molded body of the sound-absorbing material may have surfaces with recesses and / or protrusions. In this case, the surface area of ​​the polyurethane molded body is increased by the recesses and / or protrusions, resulting in a greater sound-absorbing effect.

[0016] Further, the sound-absorbing material may have a normal incidence sound absorption rate of 65% or more in the frequency range from 1000 Hz to 2500 Hz. In this case, the sound-absorbing material exhibits an even greater sound absorption effect at frequencies from 1000 Hz to 2500 Hz.

Brief Description of the Drawings

[0017] [Figure 1] It is a micrograph showing the polyurethane molded body 1a of the first embodiment in the polyurethane molded body 1 of the present invention. [Figure 2] It is a micrograph showing an enlarged part of the polyurethane molded body 1a shown in FIG. 1. [Figure 3] It is a micrograph showing the polyurethane molded body 1b of the second embodiment in the polyurethane molded body 1 of the present invention. [Figure 4] It is a micrograph showing an enlarged part of the polyurethane molded body 1b shown in FIG. 3. [Figure 5] It is a micrograph of the polyurethane molded body 1 of the present invention before the rigid polyurethane foam is pulverized. <x [Figure 6] The polyurethane molded body 20a of the first embodiment in the polyurethane molded body 20 of the present invention is shown, where (a) is a perspective view and (b) is a cross-sectional view taken along the longitudinal direction. [Figure 7] The polyurethane molded body 20b of the second embodiment in the polyurethane molded body 20 of the present invention is shown, where (a) is a perspective view and (b) is a cross-sectional view taken along the longitudinal direction. [Figure 8] The polyurethane molded body 20c of the third embodiment in the polyurethane molded body 20 of the present invention is shown, where (a) is a perspective view and (b) is a cross-sectional view taken along the longitudinal direction. [Figure 9] The polyurethane molded body 20d of the fourth embodiment in the polyurethane molded body 20 of the present invention is shown, where (a) is a perspective view and (b) is a cross-sectional view taken along the longitudinal direction. [Figure 10]The image shows a polyurethane molded article 20e according to the fifth embodiment of the polyurethane molded article 20 of the present invention, where (a) is a perspective view and (b) is a cross-sectional view taken along the longitudinal direction. [Figure 11] (a) is a perspective view showing the sound-absorbing material 8c of the present invention, where the convex portion 34 is a conical convex portion 34a. (b) to (d) are enlarged views of (a) as seen in the direction F. (b) shows the case where the tip of the conical convex portion 34a is a hemispherical arc shape. (c) shows the case where the tip is planar. (d) shows the case where the tip is pointed. [Figure 12] Figure 11 shows the case where the sound-absorbing material 8c is provided with a base material 40, (a) shows the case where the polyurethane molded layer 9 sandwiches the base material 40, and (b) shows the case where the base material 40 is provided on the bottom side. [Figure 13] (a) is a perspective view showing the sound-absorbing material 8c of the present invention, where the convex portion 34 is a square pyramidal convex portion 34b. (b) to (d) are enlarged views of (a) as seen in the G direction. (b) shows the case where the tip of the square pyramidal convex portion 34b is a hemispherical arc shape. (c) shows the case where the tip is planar. (d) shows the case where the tip is pointed. [Figure 14] (a) is a perspective view showing the sound-absorbing material 8c of the present invention, where the protrusion 34 is a wave-shaped protrusion 34c. (b) to (d) are enlarged views of (a) as seen in the J direction, where (b) shows the case where the tip of the wave-shaped protrusion 34c is a semicircular arc shape, (c) shows the case where the tip is planar, and (d) shows the case where the tip is pointed. [Figure 15] This is a perspective view showing the sound-absorbing material 8c of the present invention, where the protrusion 34 is a grid-like protrusion 34d. [Figure 16] (a) is a perspective view showing the sound-absorbing material 8c of the present invention, where the protrusion 34 is a plate-shaped protrusion 34e. (b) to (d) are enlarged views of (a) as seen in the K direction. (b) shows the case where the tip of the plate-shaped protrusion 34e is a semicircular arc shape. (c) shows the case where the tip is planar. (d) shows the case where the tip is pointed. [Figure 17](a) is a perspective view showing the sound-absorbing material 8d of the present invention, showing the case in which a recess 35 is formed, (b) to (d) are partially enlarged views (cross-sectional views) of (a) as seen in the M direction, (b) shows the case in which the tip of the recess is in the shape of a hemispherical arc, (c) shows the case in which the tip is in the shape of a plane, and (d) shows the case in which the tip is in the shape of a pointed shape. [Figure 18] This is a perspective view showing the sound-absorbing material 8e of the present invention, illustrating the case in which the convex portion 34 and the concave portion 35 are formed. [Figure 19] This figure illustrates a first embodiment of the method for manufacturing the polyurethane molded article 1 and sound-absorbing material 8 of the present invention, and is a schematic perspective view showing the manufacturing process. [Figure 20] This is a flowchart showing the steps of the first embodiment of the polyurethane molded article manufacturing method of the present invention. [Figure 21] This figure illustrates a second embodiment of the method for manufacturing the polyurethane molded article 1 and sound-absorbing material 8 of the present invention, and is a schematic perspective view showing the manufacturing process. [Figure 22] This is a flowchart showing the steps of the second embodiment of the polyurethane molded article manufacturing method of the present invention. [Figure 23] This figure illustrates a third embodiment of the method for manufacturing the polyurethane molded article 1 and sound-absorbing material 8 of the present invention, and is a schematic perspective view showing the manufacturing process. [Figure 24] This is a flowchart showing the steps of the third embodiment of the polyurethane molded article manufacturing method of the present invention. [Figure 25] This figure illustrates a fourth embodiment for manufacturing the polyurethane molded body 20 and sound-absorbing material 8c of the present invention, and is a schematic perspective view showing the manufacturing process. [Figure 26] This is a flowchart showing the steps of the fourth embodiment of the polyurethane molded article manufacturing method of the present invention. [Figure 27] These are the measurement results for Example 1, Example 2, and Comparative Example 1. [Figure 28] This is comparative data showing the normal incidence sound absorption coefficients of Example 1, Example 2, and Comparative Example 1 measured in the frequency range of 500 Hz or higher. [Figure 29] These are the measurement results for Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3. [Figure 30] This is comparative data showing the normal incidence sound absorption coefficients of Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 measured in the frequency range between 100 Hz and 3100 Hz. [Figure 31] This is comparative data showing the normal incidence sound absorption coefficients of Example 3 and Comparative Example 4 measured in the frequency range between 500 Hz and 2500 Hz. [Modes for carrying out the invention]

[0018] The following describes the polyurethane molded article 1, the polyurethane molded article 20, the sound-absorbing material 8, and the method for manufacturing the polyurethane molded article, all of which embody the present invention, with reference to the drawings. The embodiments for carrying out the invention and the referenced drawings are used to illustrate the technical features that the present invention may employ. The present invention is not limited to these. The configuration of the apparatus shown in the drawings is not intended to limit the invention to that configuration only, but is merely an illustrative example.

[0019] <Common features of polyurethane molded articles 1 etc. according to the first embodiment> A polyurethane molded article 1 and a polyurethane molded article 20 according to a first aspect of the present invention will be described below. Hereinafter, the polyurethane molded article 1 and the polyurethane molded article 20 will be collectively referred to as the polyurethane molded article 1, etc. Each embodiment will be described later, but first, the common configuration will be described. As shown in Figures 1 to 4, the polyurethane molded article 1, etc. comprises a polyurethane fragment 2, a connecting portion 3 that connects a plurality of adjacent polyurethane fragments 2 to each other, and a communication hole 4. The fragment 2 is molded in such a state that at least a part of it is bent, and at least a part of it has an end portion 5 that is separated from the adjacent fragment 2.

[0020] For example, fragment 2 is a fragment of the outer shell 11 that forms the cell 10 of rigid polyurethane foam. Figures 1 to 4 are micrographs of compression-molded polyurethane molded articles, etc., which are examples of materials such as polyurethane molded articles 1, etc., which are made by crushing rigid polyurethane foam. Note that the materials such as polyurethane molded articles 1 are not limited to rigid polyurethane, but can be made of polyurethane. Also, the polyurethane molding material 21, which is fragment 2 made of polyurethane, does not have to be crushed, but can be of a size as described later. As shown in Figure 5, rigid polyurethane foam is a polyurethane foam that has cells 10 with an independent structure.

[0021] As shown in Figures 2 and 4, the communication holes 4 appear as dark shadows, but they are not closed by the fragments 2, and the communication holes 4 are interconnected and interwoven within the polyurethane molded body 1. The fragments 2 are not planar but are irregularly bent and refracted, and are integrally molded by joining with other adjacent fragments 2 at the joint 3.

[0022] As shown in Figures 1 to 4, for example, a polyurethane molded body 1 is formed by crushing the outer shell 11 of a rigid polyurethane foam cell 10 to form fragments 2, and then compression molding while bonding parts 3 are formed with adhesive 22. The manufacturing method will be described later. Adhesives 22 suitable for each manufacturing method will also be described later. Figure 5 is a micrograph showing the state of the rigid polyurethane foam before it is crushed. Figure 5 is at the same magnification as Figures 1 and 3.

[0023] As shown in Figure 5, the rigid polyurethane foam before crushing has cells 10 surrounded by an outer shell 11. Each cell 10 is independent, and compared to after crushing, the cells 10 are clearly visible and it is difficult for them to communicate with adjacent cells 10. Furthermore, the area surrounded by the outer shell 11 is wide in the cells 10 before crushing. In contrast, the polyurethane molded bodies 1 shown in Figures 1 and 3 are in a state where the outer shell 11 is divided and compressed, and the cells 10 are crushed. The outer shell 11 is divided and fragmented to form fragments 2, and the fragments 2 are further compressed and irregularly bent. In addition, the fragments 2 are connected by bonding parts 3 formed by adhesive 22, creating communication holes 4 and further integrating them.

[0024] Furthermore, as shown in Figures 2 and 4, at least a portion of the end portion 5 of the fragment 2 is formed in a pleated shape and protrudes into the communication hole 4, resulting in an unrestrained free end.

[0025] Furthermore, as shown in Figures 2 to 4, fragment 2 has a missing portion 6 in at least a part of it. The blackened area in part of fragment 2, as if there is a hole, is the missing portion 6. Unlike the communication hole 4, the missing portion 6 is formed in a single fragment 2. The missing portion 6 allows adjacent regions on either side of fragment 2 to communicate with each other.

[0026] Furthermore, the breathability of polyurethane molded body 1, etc., is 4.68 cm. 3 / cm 2 • 6.93 cm³ / cm for sizes S and above 2 The breathability is less than or equal to s. The breathability was measured based on "JIS L 1096 Fabric Testing Methods for Woven and Knitted Fabrics". The breathability is obtained by the communication holes 4 and the defects 6.

[0027] Next, the normal incidence sound absorption coefficient of the polyurethane molded article 1 will be explained with reference to Figures 28 and 30. In Figures 28 and 30, the polyurethane molded article 1 corresponds to A and B, respectively. The polyurethane molded article 1 has a normal incidence sound absorption coefficient of 50% or more in the frequency range from 400 Hz to 6500 Hz. Furthermore, as shown in Figure 28, the polyurethane molded article 1 has a normal incidence sound absorption coefficient of 55% or more in the frequency range from 700 Hz to 6500 Hz. Moreover, the polyurethane molded article 1 has a normal incidence sound absorption coefficient of 60% or more in the frequency range from 2000 Hz to 6500 Hz. The measurement method and detailed measurement results of the normal incidence sound absorption coefficient will be explained in the description of each embodiment and in the examples.

[0028] <Effects of the common configuration of polyurethane molded articles 1 etc. according to the first embodiment> The polyurethane molded body 1, etc., as described above, has the following effects. As shown in Figures 1 to 4, the polyurethane molded body 1, etc., has a communication hole 4 that connects the fragment 2 and the joint 3, so it is breathable. Furthermore, the fragments 2 are joined to each other at the joint 3, and at least a part of them is in a bent state, and at least a part of them has an end 5 that is separated from the adjacent fragment 2. Therefore, the polyurethane molded body 1, etc., attenuates sound vibrations and exhibits a sound absorption effect.

[0029] Furthermore, since the end portion 5 of fragment 2 is formed in a pleated shape and protrudes into the communication hole 4, sound vibrations are more easily attenuated, resulting in a greater sound absorption effect.

[0030] Furthermore, since fragment 2 has a defect 6 in addition to the communication hole 4, it can be made more breathable, which disperses the transmitted sound vibrations over a wider area and increases the sound absorption effect.

[0031] Furthermore, since the polyurethane molded body 1 has an appropriate range of breathability, it provides both sound absorption and heat insulation effects.

[0032] Next, the sound-absorbing effect of polyurethane molded article 1 will be explained. Polyurethane molded article 1 has a normal incidence sound absorption coefficient of 50% or more in the frequency range from 400 Hz to 6500 Hz, thus exhibiting a sound-absorbing effect over a wide frequency range. Furthermore, polyurethane molded article 1 has a normal incidence sound absorption coefficient of 55% or more in the frequency range from 700 Hz to 6500 Hz, thus exhibiting an even greater sound-absorbing effect in the frequency range from 700 Hz to 6500 Hz. Moreover, in the frequency range from 2000 Hz to 6500 Hz, the normal incidence sound absorption coefficient is 60% or more, thus exhibiting an even greater sound-absorbing effect in the frequency range from 2000 Hz to 6500 Hz.

[0033] <Description of each embodiment of the polyurethane molded body 1 according to the first embodiment> Next, with reference to Figures 1 to 4, the first embodiment of the polyurethane molded body 1, polyurethane molded body 1a, and the second embodiment, polyurethane molded body 1b, will be described. In the first embodiment, polyurethane molded body 1a is made of polyurethane molding material 21, which is a polyurethane fragment 2, that has been previously passed through a sieve with a mesh size of 2 mm. In contrast, in the second embodiment, polyurethane molded body 1b is made of polyurethane molding material 21, which is a polyurethane fragment 2, that has not been previously passed through a sieve with a mesh size of 2 mm.

[0034] The polyurethane molding material 21 is, for example, obtained by crushing rigid polyurethane foam, and the polyurethane molded body 1a and polyurethane molded body 1b have different particle sizes. Note that the polyurethane molding material 21 may also be formed by methods other than crushing.

[0035] Figures 1 and 2 are micrographs showing polyurethane molded body 1a, and Figures 3 and 4 are micrographs showing polyurethane molded body 1b. In both cases, a polyurethane molding material 21 obtained by crushing rigid polyurethane foam was used as an example and compressed. Figures 1 and 3 are at the same magnification. Comparing Figures 1 and 3, as shown in Figure 1, in polyurethane molded body 1a, a large proportion of the outer shell 11 of the cell 10 is fragmented, with most of it being fragmented into fragments 2, and moreover, the fragments 2 are fine. The joint 3 joins the fragments 2, forming an apparent cell 12 including the communication holes 4 in a roughly uniform manner. Here, the apparent cell 12 refers to the area where a part of the outer shell 11 is formed by the fragments 2 and appears cell-like, but it is given the provisional name "apparent" because the outline is unclear. The apparent cell 12 shown in Figures 1 to 4 shows an approximate outline.

[0036] Furthermore, as shown in Figures 1 and 2, the polyurethane molded body 1a has more of its end portion 5 formed in a pleated shape compared to the polyurethane molded body 1b, and protrudes into the communication hole 4. The fragment 2 is crushed and bent, forming a fold line 7.

[0037] As shown in Figure 3, the polyurethane molded body 1b has some cells 10 remaining, and the spacing between adjacent communication holes 4 is wider compared to the polyurethane molded body 1a. The remaining cells 10 and the apparent cells 12 formed by the bonding portion 3 joining the fragments 2 are mixed together, resulting in a non-uniform appearance. However, although the proportion of apparent cells 12 is smaller in the polyurethane molded body 1b compared to the polyurethane molded body 1a, the outer shell 11 of the cells 10 is divided to form fragments 2, and the bonding portion 3 and communication holes 4 are formed. Furthermore, a defect 6 is formed in part of the fragment 2.

[0038] <Effects of each embodiment of the polyurethane molded body 1 according to the first embodiment> As described above, the polyurethane molded body 1a, which is the first embodiment of the polyurethane molded body 1, and the polyurethane molded body 1b, which is the second embodiment, provide the following effects. The characteristic values ​​of the polyurethane molded body 1a and the polyurethane molded body 1b will be described in the examples below, but both possess both thermal insulation and sound absorption properties.

[0039] Compared to polyurethane molded body 1b, polyurethane molded body 1a has a smaller amount of material before compression, resulting in a higher density after compression molding and more uniform formation of fragments 2, joints 3, and communication holes 4. Therefore, polyurethane molded body 1a exhibits more stable heat insulation and sound absorption even when used in partial pieces.

[0040] Furthermore, the polyurethane molded body 1b has a low density after compression molding, making it possible to reduce its weight. It can also further enhance sound absorption. The structure and effects of the polyurethane molded body 1 described above are the same as those of the polyurethane molded layer 9 in the polyurethane molded body 20 described later.

[0041] <Structure and effects of the polyurethane molded article 20 according to the first embodiment> Next, a polyurethane molded article 20 according to a first aspect of the present invention will be described. As shown in Figures 6 to 10, the polyurethane molded article 20 comprises a polyurethane molded layer 9 and a base material 40. The polyurethane molded layer 9 corresponds to the polyurethane molded article 1 described with reference to Figures 1 to 4, and comprises polyurethane fragments 2, connecting parts 3 that connect a plurality of adjacent fragments 2 to each other, and communication holes 4. The fragments 2 are molded so that at least a part of them is in a bent state, and at least a part of them has an end 5 that is separated from the adjacent fragments 2. The polyurethane molded layer 9 and the base material 40 are at least partially bonded to each other. The polyurethane molded layer 9 and the base material 40 are integrally molded by a polyurethane molded article manufacturing method described later. Alternatively, the polyurethane molded layer 9 and the base material 40 are bonded together with an adhesive 22. The base material 40 is, for example, MDF. MDF is a medium-density fiberboard and refers to a board material. In this example, MDF is used, but other materials that have a reinforcing effect can be used for the base material 40.

[0042] The polyurethane molded article 20 according to the first embodiment of the present invention, as described above, provides the following common effects in each embodiment. Since at least a portion of the polyurethane molded layer 9 and the base material 40 are bonded to each other, the strength of the polyurethane molded article 20 is increased by the base material 40. In addition, the polyurethane molded article 20 can have its sound insulation or sound absorption properties enhanced depending on its form. Therefore, the polyurethane molded article 20 can be used as a heat insulating material and / or a sound absorbing material.

[0043] Next, each embodiment of the polyurethane molded body 20 will be described. Referring to Figure 6, the polyurethane molded body 20a, which is the first embodiment of the polyurethane molded body 20, will be described. In the polyurethane molded body 20a, the polyurethane molded layer 9 has its top surface 9a and bottom surface 9b covered by the base material 40. The sides may be exposed. As shown in Figure 6(b), the polyurethane molded body 20a is integrally molded so that the base material 40 is bonded to the top surface 9a and bottom surface 9b of the polyurethane molded layer 9. Alternatively, the base material 40 is bonded to the top surface 9a and bottom surface 9b of the polyurethane molded layer 9. Although both the polyurethane molded body 20a and the polyurethane molded body 20b, which will be described next, have been described as having a three-layer structure in the thickness direction, a two-layer structure of polyurethane molded layer 9 and base material 40 is also possible.

[0044] The polyurethane molded body 20a, which is the first embodiment of the polyurethane molded body 20 described above, provides the following effects. As shown in Figure 6, in the polyurethane molded body 20a, the polyurethane molded layer 9 is sandwiched between the base material 40, with its top surface 9a and bottom surface 9b. Therefore, the polyurethane molded body 20a has high strength. In addition, since the polyurethane molded layer 9 is sandwiched between the base material 40, the polyurethane molded body 20a has sound insulation properties.

[0045] Next, with reference to Figure 7, a second embodiment of the polyurethane molded body 20, the polyurethane molded body 20b, will be described. The base material 40 of the polyurethane molded body 20b is covered on its top surface 40a and bottom surface 40b by a polyurethane molded layer 9. The sides may be left exposed. As shown in Figure 7(b), the polyurethane molded body 20b is integrally molded so that the polyurethane molded layer 9 is bonded to the top surface 40a and bottom surface 40b of the base material 40. Alternatively, the polyurethane molded layer 9 is bonded to the top surface 40a and bottom surface 40b of the base material 40.

[0046] The polyurethane molded body 20b, which is the second embodiment of the polyurethane molded body 20 described above, provides the following effects. As shown in Figure 7, in the polyurethane molded body 20b, the base material 40 is covered with a polyurethane molded layer 9 on both the top surface 40a and the bottom surface 40b. Therefore, the polyurethane molded body 20b has sound-absorbing properties. In addition, the strength is increased by the base material 40.

[0047] Next, with reference to Figure 8, a third embodiment of the polyurethane molded body 20, the polyurethane molded body 20c, will be described. The base material 40 of the polyurethane molded body 20c is covered on its outer circumference by a polyurethane molded layer 9. For example, the base material 40 is in the shape of a rectangular parallelepiped. As shown in Figure 8(b), in the polyurethane molded body 20c, the base material 40 is covered by the polyurethane molded layer 9 in the thickness direction and the longitudinal direction. Although not shown, a cross-sectional view cut along the width direction similarly shows the base material 40 covered by the polyurethane molded layer 9 in the thickness direction and the width direction.

[0048] The polyurethane molded body 20c, which is the third embodiment of the polyurethane molded body 20 described above, provides the following effects. As shown in Figure 8, in the polyurethane molded body 20c, the outer periphery of the base material 40 is covered by the polyurethane molded layer 9, and the polyurethane molded layer 9 is exposed on the outer periphery. Therefore, the polyurethane molded body 20c has sound-absorbing properties.

[0049] Next, with reference to Figure 9, a fourth embodiment of the polyurethane molded body 20, the polyurethane molded body 20d, will be described. As shown in Figure 9, the polyurethane molded layer 9 of the polyurethane molded body 20d is covered on its outer circumference by the base material 40. As shown in Figure 9(b), in the polyurethane molded body 20d, the polyurethane molded layer 9 is covered by the base material 40 in the thickness direction and the longitudinal direction. Although not shown, in a cross-sectional view cut along the width direction, the polyurethane molded layer 9 is similarly covered by the base material 40 in the thickness direction and the width direction. As shown in the example in Figure 9(b), the base material 40 comprises a bottom box 40c and a lid 40d, and the polyurethane molded body 20b has the polyurethane molded layer 9 integrally molded inside the base material 40. Alternatively, the polyurethane molded layer 9 is bonded to the inside of the base material 40.

[0050] The polyurethane molded body 20d, which is the fourth embodiment of the polyurethane molded body 20 described above, provides the following effects. As shown in Figure 9, the polyurethane molded body 20d has increased strength because the outer circumference of the polyurethane molded layer 9 is covered by the base material 40. In addition, it is possible to prevent the polyurethane molded layer 9 from falling off.

[0051] Next, with reference to Figure 10, a fifth embodiment of the polyurethane molded body 20, the polyurethane molded body 20e, will be described. As shown in Figure 10, the polyurethane molded layer 9 of the polyurethane molded body 20e is covered on its sides by the base material 40, with the top surface 9a and bottom surface 9b exposed. As shown in Figure 10(a), the base material 40 is frame-shaped with through holes on the inside, and the polyurethane molded body 20e is formed by integrally molding the polyurethane molded layer 9 inside the base material 40. Alternatively, the polyurethane molded layer 9 is bonded to the inside of the base material 40.

[0052] The polyurethane molded body 20e, which is the fifth embodiment of the polyurethane molded body 20 described above, provides the following effects. As shown in Figure 10, in the polyurethane molded body 20e, the polyurethane molded layer 9 has its sides covered by the base material 40, with the top surface 9a and bottom surface 9b exposed and the sides covered by the base material 40. Therefore, the polyurethane molded body 20e has increased strength. In addition, since the top surface 9a and bottom surface 9b of the polyurethane molded layer 9 are exposed, it has sound-absorbing properties. Furthermore, it is possible to prevent the polyurethane molded layer 9 from falling off from the sides.

[0053] <Configuration and effects of sound-absorbing material 8 according to a second aspect of the present invention> Next, a sound-absorbing material 8 according to a second aspect of the present invention will be described. As shown in Figure 19(c), the sound-absorbing material 8 may be used as is, using the polyurethane molded body 1, or it may be fitted into a predetermined frame or the like. Furthermore, as will be described later, as shown in Figures 11 to 18, it may have surfaces with recesses and / or protrusions, and there are no particular restrictions on shape and size. First, the relationship between frequency and normal incidence sound absorption coefficient in the sound-absorbing material 8 will be explained with reference to Figures 28 and 30. As shown in Figure 28, the sound-absorbing material 8 made of polyurethane molded body 1 has a normal incidence sound absorption coefficient of 55% or more in the frequency range from 700 Hz to 6500 Hz. Also, in the frequency range from 2000 Hz to 6500 Hz, it has a normal incidence sound absorption coefficient of 60% or more. In Figure 28, A shows polyurethane molded body 1a, B shows polyurethane molded body 1b, and C shows rigid polyurethane foam.

[0054] Furthermore, as shown in Figure 30, the sound-absorbing material 8 made of polyurethane molded body 1 has a normal incidence sound absorption coefficient of 50% or more in the frequency range from 400 Hz to 6500 Hz. The normal incidence sound absorption coefficient of the sound-absorbing material 8 increases sharply from 100 Hz, peaking around 700 Hz to 800 Hz. In Figure 30, A and C are the same as in Figure 28, D represents rock wool, and E represents glass wool.

[0055] As explained above, the sound-absorbing material 8 made of polyurethane molded body 1 exhibits a rapidly increasing normal incidence sound absorption coefficient as the frequency increases from 100 Hz, with a normal incidence sound absorption coefficient of 50% or more in the frequency range from 400 Hz to 6500 Hz. The frequency range of human speech is generally considered to be between 250 Hz and 4000 Hz. The sound-absorbing material 8 exhibits a sound-absorbing effect against human speech. Furthermore, the sound-absorbing material 8 exhibits an even greater sound-absorbing effect in the frequency range from 700 Hz to 6500 Hz, with a normal incidence sound absorption coefficient of 55% or more. Moreover, the sound-absorbing material 8 exhibits an even greater sound-absorbing effect in the high-frequency range from 2000 Hz to 6500 Hz. The normal incidence sound absorption coefficient shown in Figure 28 will be explained in detail in the examples. Note that the normal incidence sound absorption coefficient explained above is the measured value when the sound-absorbing material 8 is in the shape of a roughly rectangular parallelepiped flat plate. The case where the surface has irregularities will be explained next.

[0056] <Description of sound-absorbing material 8 with an uneven surface> Next, referring to Figures 11 to 18, sound-absorbing materials 8c to 8j of the sound-absorbing material 8 made of polyurethane molded body 1 will be described. Sound-absorbing materials 8c to 8g have a surface 31 having a recess 33 and / or a protrusion 34. Sound-absorbing materials 8h and 8j have a surface 31 having a recess 35 and / or a protrusion 34. As an example, as shown in Figure 11, the case in which the sound-absorbing material 8 has a predetermined thickness and has a first surface 31a and a second surface 31b facing each other will be described. At least one of the first surface 31a and the second surface 31b has a recess 33 and / or a protrusion 34, or a recess 35 and / or a protrusion 34. Here, the recess 33 indicates the valley between the protrusions 34 and the protrusions 34, as shown in Figure 14, and the recess 35 indicates that it is formed recessed from the surface 31, as shown in Figure 17.

[0057] The protrusions 34 may be arranged regularly in a grid pattern, for example, or they may be formed randomly. Similarly, the recesses 35 may be arranged regularly in a grid pattern, for example, or they may be formed randomly. Examples of the recesses 33, recesses 35, and protrusions 34 will be described below.

[0058] The sound-absorbing material 8c will be described with reference to Figure 11. The sound-absorbing material 8c is shown in the case where the protrusions 34 are conical protrusions 34a. As shown in Figure 11(a), the conical protrusions 34a are formed in a grid pattern. The tip of the conical protrusion 34a may be rounded in a hemispherical shape as shown in Figure 11(b), flat as shown in Figure 11(c), or pointed as shown in Figure 11(d). The relationship between the thickness L and the height h of the protrusion can be set arbitrarily. The thickness L may be greater than or equal to the height h of the protrusion. The same applies to the other protrusions 34 described below. The spacing between adjacent conical protrusions 34a may be equal or random. Note that in the example shown in Figure 11, the protrusion 34 is a conical protrusion 34a, but the protrusion 34 may be a cylinder. Furthermore, in the embodiment 4 described later, the protrusion 34 is a conical protrusion 34a as shown in Figure 11.

[0059] The example shown in Figure 12, in contrast to the example shown in Figure 11, shows a case where the polyurethane molded layer 9, which is part of the sound-absorbing material 8c, is bonded to the base material 40. The example shown in Figure 12(a) shows a case where the base material 40 is sandwiched between the polyurethane molded layer 9 having a conical protrusion 34a in the thickness direction and the lower polyurethane molded layer 9. The example shown in Figure 12(b) shows a case where the base material 40 is the lower layer of the polyurethane molded layer 9 having a conical protrusion 34a in the thickness direction.

[0060] The sound-absorbing material 8d will be described with reference to Figure 13. The sound-absorbing material 8d is shown in the case where the protrusions 34 are square pyramidal protrusions 34b. As shown in Figure 13(a), the square pyramidal protrusions 34b are formed in a grid pattern, similar to the example in Figure 11. The tips of the square pyramidal protrusions 34b may be rounded in a hemispherical shape as shown in Figure 13(b), flat as shown in Figure 13(c), or pointed as shown in Figure 13(d). The spacing between adjacent square pyramidal protrusions 34b may be equal or random. Note that in the example shown in Figure 13, the protrusions 34 are square pyramidal protrusions 34b, but the protrusions 34 may be polygonal pyramids other than square pyramids, or polygonal prisms.

[0061] The sound-absorbing material 8e will be described with reference to Figure 14. The sound-absorbing material 8e has convex portions 34 which are wave-shaped convex portions 34c, and as shown in Figure 14(a), they are formed continuously in one direction and are wave-shaped with the recess 33 in between. The spacing between adjacent wave-shaped convex portions 34c may be equal or random. In the example shown in Figure 14, adjacent wave-shaped convex portions 34c are formed independently, but they may also be connected by a smooth curve with the recess 33 in between. The tip of the wave-shaped convex portion 34c may be rounded in a semi-circular shape as shown in Figure 14(b), flat as shown in Figure 14(c), or pointed as shown in Figure 14(d).

[0062] The sound-absorbing material 8f will be described with reference to Figure 15. The sound-absorbing material 8f shows the case where the protrusions 34 are grid-shaped protrusions 34d. The wave-shaped protrusions 34c described with reference to Figure 14 are formed in a grid pattern so that they intersect with each other. The spacing between adjacent grid-shaped protrusions 34d may be equal or random. In the example shown in Figure 15, adjacent grid-shaped protrusions 34d are formed independently, but they may also be connected by a smooth curve across the recess 33. The tip shape of the grid-shaped protrusions 34d is the same as that of the wave-shaped protrusions 34c described with reference to Figure 14.

[0063] Referring to Figure 16, the sound-absorbing material 8g will be described. The sound-absorbing material 8g is shown in the case where the protrusions 34 are plate-shaped protrusions 34e. As shown in Figure 16(a), several plate-shaped protrusions 34e are formed in sets with a recess 33 in between, and the direction in which the plate-shaped protrusions 34e extend differs by 90 degrees between adjacent sets. The spacing between adjacent plate-shaped protrusions 34e may be equal or random. The gaps between each set may also be equal or random. The tip of the plate-shaped protrusion 34e may be rounded in a semi-circular shape as shown in Figure 16(b), flat as shown in Figure 16(c), or pointed as shown in Figure 16(d).

[0064] Referring to Figure 17, the sound-absorbing material 8h will be described. The sound-absorbing material 8h is shown in the case where only the recess 35 is formed. As shown in Figure 17(a), the recess 35 is formed by recessing from the first surface 31a. The recess 35 is conical as an example. The depth d of the recess 35 may be the same as or different from the height h of the convex portion 34. In addition, the recess 35 may be cylindrical, polygonal prism, or polygonal pyramidal. An example of the recess 35 being arranged in a grid is shown, but it may also be random. The tip of the recess 35 may be rounded in a hemispherical shape as shown in Figure 17(b), flat as shown in Figure 17(c), or pointed as shown in Figure 17(d).

[0065] The sound-absorbing material 8j will be described with reference to Figure 18. The sound-absorbing material 8j shows an example in which conical protrusions 34a and recesses 35 are arranged alternately in a grid pattern. The conical protrusions 34a protrude from the first surface 31a, and the recesses 35 are formed by recessing from the first surface 31a. The conical protrusions 34a and recesses 35 are shown arranged in a grid pattern, but they may be arranged randomly. The tip shape of the conical protrusions 34a is the same as the shape described with reference to Figures 11(b) to 11(d), and the tip shape of the recesses 35 is the same as the shape described with reference to Figures 17(b) to 17(d).

[0066] The sound-absorbing materials 8c to 8j described above have the following characteristics. As a representative example, sound-absorbing material 8c will be described. As will be explained in detail in the examples described later, Example 3 shown in Figure 31 is sound-absorbing material 8c. Sound-absorbing material 8c has a normal incidence sound absorption coefficient of 65% or more between 1000 Hz and 2500 Hz. Furthermore, between 1400 Hz and 1800 Hz, its normal incidence sound absorption coefficient is 70% or more.

[0067] The above examples describe cases where the protrusions 34, recesses 33, and recesses 35 are formed only on the first surface 31a, but they may also be formed on the second surface 31b, or on both the first surface 31a and the second surface 31b. Furthermore, the protrusions 34 or recesses 33 and recesses 35 may have different shapes on the first surface 31a and the second surface 31b. In addition, the example described uses a plate-shaped sound-absorbing material 8, but it is not limited to this. For example, the sound-absorbing material 8 may be spherical, polygonal pyramidal, polygonal prism-shaped, conical, or any other shape, and the method is applicable.

[0068] <Effects of sound-absorbing materials with an uneven surface> As described above, sound-absorbing materials 8c to 8j produce the following effects. Sound-absorbing materials 8c to 8j produce a greater sound-absorbing effect because the surface area of ​​the polyurethane molded body 1 is increased by the recesses 33 and / or protrusions 34. In other words, the surface area of ​​the polyurethane molded body 1 is increased by at least one of the recesses 33, recesses 35, and protrusions 34, resulting in a greater sound-absorbing effect. When the area of ​​the polyurethane molded body 1 increases, there are more air passages for transmitting sound vibrations, and the sound-absorbing effect becomes greater compared to a flat plate with no surface irregularities.

[0069] Furthermore, in the case of the sound-absorbing materials 8c shown in Figure 11 to 8f shown in Figure 15, and the sound-absorbing material 8e shown in Figure 18, the shape of the protrusion 34 is such that each side surface of the protrusion 34 is inclined at a predetermined angle with respect to the thickness direction, allowing sound-transmitting air to be incident from multiple angles. Also, in the case of the sound-absorbing material 8h shown in Figure 17 and the sound-absorbing material 8j shown in Figure 18, the inner surface of the recess 35 is inclined at a predetermined angle, allowing sound-transmitting air to be incident from multiple angles. Therefore, sound-absorbing materials 8c to 8j exhibit a greater sound-absorbing effect.

[0070] Furthermore, when the surface 31 having the protrusions 34 is used in contact with other members such as a wall, air can pass between the protrusions 34, thus ensuring ventilation.

[0071] Furthermore, the sound-absorbing material 8c, as explained with reference to Figure 12, is formed by bonding the polyurethane molded layer 9 with the base material 40, and therefore exhibits the effects of the polyurethane molded body 20a and others already described.

[0072] Furthermore, as shown in Figure 31, the sound-absorbing material 8c has a normal incidence sound absorption coefficient of 65% or more between 1000 Hz and 2500 Hz, and a normal incidence sound absorption coefficient of 70% or more between 1400 Hz and 1800 Hz. Therefore, the sound-absorbing material 8c exhibits a large sound absorption effect at frequencies from 1000 Hz to 2500 Hz. Moreover, it exhibits an even greater sound absorption effect between 1400 Hz and 1800 Hz.

[0073] <<Explanation of Polyurethane Molded Article Manufacturing Method>> Next, a third embodiment of the present invention's method for manufacturing a polyurethane molded article will be described with reference to Figures 19 to 26. The polyurethane molded article manufacturing method is a method for manufacturing a polyurethane molded article 1, a polyurethane molded article 20, and a sound-absorbing material 8. First, a process common to all polyurethane molded article manufacturing methods will be described. The polyurethane molded article manufacturing method may include a preliminary step S0 before the first step S1, in which polyurethane foam is crushed to form polyurethane fragments 2 and polyurethane molding material 21 is formed. The preliminary step S0 is optional. That is, there are cases in which the preliminary step S0 is incorporated into the series of manufacturing steps, and cases in which the process starts from the first step S1 described later using polyurethane molding material 21 that has already been crushed or otherwise processed. The polyurethane foam is, for example, rigid polyurethane foam.

[0074] As shown in Figures 20, 22, 24, and 26, if a preliminary step S0 is included, the preliminary step S0 includes steps P1 and P2. The first step S1 includes steps P3 and P4. The second step S2 includes steps P5 and P6.

[0075] The case in which a preliminary step S0 is included will be described. The polyurethane molding material 21 is, for example, rigid polyurethane foam. Before crushing, the rigid polyurethane foam has cells 10 surrounded by an outer shell 11, as shown in Figure 5. The rigid polyurethane foam used is, for example, industrial waste or scraps generated in the production process. In this case, as shown in the examples in Figures 19 and 20, the polyurethane molded article manufacturing method includes a rigid polyurethane foam recovery step P1 for recovering the material and a rigid polyurethane foam crushing step P2.

[0076] Step P2 is a rigid polyurethane foam crushing process that fragments the outer shell 11 forming the cells 10 of the rigid polyurethane foam to form fragments 2. In step P2, the rigid polyurethane foam is crushed to a predetermined size. As shown in Example 1 described later, the polyurethane molding material 21 may be rigid polyurethane foam that has been crushed and passed through a sieve with a mesh size of 2 mm in advance. As already explained, the state of the fragments 2, joints 3, connecting holes 4, and defects 6 after molding differs depending on the size of the chips after crushing. Hereafter, the molding material used in this manufacturing method will be referred to as polyurethane molding material 21, including cases where the rigid polyurethane foam is not crushed but has been processed to a predetermined size in advance. If the rigid polyurethane foam is not waste, step P1 is omitted. Also, if the polyurethane molding material 21 is pre-crushed or of a predetermined fine size, step P2 of the rigid polyurethane foam crushing process is omitted.

[0077] The polyurethane molded article manufacturing method, if it includes a preliminary step S0, proceeds to the first step S1 after the preliminary step S0. If it does not include a preliminary step S0, the preliminary step S0 is omitted and the process starts from the first step S1. As shown in Figure 19, the method includes a first step S1 in which a polyurethane molding material 21 and an adhesive 22 are mixed and put into molds 24 and 25, and a second step S2 in which compression molding is performed in the molds 24 and 25. In the second step S2, a joint 3 is formed in which a plurality of adjacent fragments 2 are joined together, and a communication hole 4 is formed. At least a portion of the fragment 2 forms an end 5 that is separated from the adjacent fragment 2.

[0078] The first step S1 will now be described. As shown in Figure 19, the first step S1 includes steps P3 and P4. As shown in the example in Figure 19(a), step P3 involves putting the polyurethane molding material 21 and adhesive 22 into a mixing container 41 and mixing them by vibrating the mixing container 41 in multiple directions. The adhesive 22 is selected and used according to the appropriate embodiment, which will be described later. Step P4 differs slightly depending on the embodiment. In the first to third embodiments, step P4 is the process of putting the polyurethane molding material 21, etc., into molds 24 and 25. Step P4 in the fourth embodiment will be described later.

[0079] The second step S2 will now be described. The second step S2 includes a step P5 in which the polyurethane molding material 21 mixed with adhesive 22 is placed into molds 24 and 25 and then compressed, and a step P6 in which the molded product is removed. Step P5 differs depending on the embodiment. Note that for sound-absorbing materials 8c shown in Figure 11 to 8j shown in Figure 18, the mold 25 has shapes such as bumps and dips formed on it. In the second step S2, the polyurethane molding material 21, etc., is molded into the respective bumps and dips by the mold 25.

[0080] <Description of the first embodiment of the polyurethane molded article manufacturing method> Next, the polyurethane molded article manufacturing method will be described for each embodiment. As already explained, the selectively provided preliminary step S0 is common to all embodiments except the third embodiment, so its explanation will be omitted. The first step S1 will be described in terms of the type of adhesive 22 used. Referring to Figures 19 and 20, the first embodiment of the polyurethane molded article manufacturing method will be described. The first to third embodiments are methods for manufacturing the polyurethane molded article 1 and the sound-absorbing material 8, and the fourth embodiment is a method for manufacturing the polyurethane molded article 20 and the sound-absorbing material 8c.

[0081] A first embodiment of a polyurethane molded article manufacturing method will be described. The type of adhesive 22 used in step P3 of the first step S1 will be described. The adhesive 22 can be a moisture-curing adhesive, a heat-curing adhesive, or a heat-melt adhesive. In particular, it is preferable to use a moisture-curing adhesive. This is because curing proceeds rapidly by introducing heated steam 28 in step P5 of the second step S2, which will be described later.

[0082] Next, the second step S2 will be explained with reference to Figures 19(b) and 20. Step P5 in the second step S2 is a step in which the polyurethane molding material 21 etc. that has been put into the molds 24 and 25 is compression molded by the molds 24 and 25. In step P5, compression molding is performed while introducing heated steam 28 into holes 26 formed on each side of the mold 24. The pressure when performing compression molding in step P5 is 0.1 MPa or higher. The pressurization time is between 3 minutes and 30 minutes.

[0083] In step P5, the polyurethane molded body 1 joins adjacent fragments 2 together to form a joint 3, and forms a communication hole 4 that connects the fragments 2 and the joint 3. In addition, at least a portion of the fragments 2 is bent, and at least a portion of the fragments 2 is separated from the adjacent fragments 2.

[0084] Next, as shown in Figures 19(c) and 20, the process includes a step P6 for removing the molded product and a step P7 for cutting the molded product according to its intended use.

[0085] <Description of the second embodiment of the polyurethane molded article manufacturing method> Next, a second embodiment of the polyurethane molded article manufacturing method will be described. This will be explained with reference to Figures 21 and 22. The type of adhesive 22 used in step P3 of the first step S1 will be described. The adhesive 22 can be a heat-curing adhesive or a heat-melt adhesive. In the first embodiment of the polyurethane molded article manufacturing method, in step P5 of the second step S2, the polyurethane molding material 21 etc. is compressed while introducing heated steam 28. In contrast, as shown in Figures 21 and 22, in step P5, instead of introducing heated steam 28, a high-temperature compression method is adopted in which the polyurethane molding material 21 etc. is compressed at a high temperature.

[0086] In the high-temperature compression method, since steam 28 is not introduced in the second step S2, there is insufficient moisture inside the molds 24 and 25, and moisture-curing adhesives cannot be used in step P3. However, compared to the molded article manufacturing method that introduces heated steam 28, as in the first embodiment of the polyurethane molded article manufacturing method, it is possible to manufacture molded articles with simpler equipment. The compression molding in step P5 is performed at a temperature of 120°C to 160°C for a time of 5 to 30 minutes. The pressure during compression is between 0.1 MPa and 0.5 MPa.

[0087] <Description of the third embodiment of the polyurethane molded article manufacturing method> Next, a third embodiment of the polyurethane molded article manufacturing method will be described with reference to Figures 23 and 24. The type of adhesive 22 used in step P3 of the first step S1 will be described. The adhesive 22 can be a moisture-curing adhesive, a heat-curing adhesive, or a heat-melt adhesive. In particular, it is preferable to use a moisture-curing adhesive. This is because, in step P5 of the second step S2, which will be described later, water 42 is introduced and heated, filling the molds 24 and 25 with steam, and curing proceeds rapidly due to the steam.

[0088] The second step S2 includes step P5, in which polyurethane molding material 21 mixed with adhesive 22 is placed into molds 24 and 25, water 42 is added to mold 24, and the material is heated and pressurized to perform compression molding. The water 42 is sprayed or otherwise mixed uniformly with the polyurethane molding material 21, etc. The amount of water 42 is, for example, between 2 and 10 times the amount of adhesive 22. The compression molding in step P5 is carried out by heating and compressing at a temperature of 120°C to 160°C for a period of 3 to 20 minutes. The pressure during compression is between 0.1 MPa and 0.5 MPa.

[0089] <Description of the fourth embodiment in the method for manufacturing polyurethane molded articles> Next, a fourth embodiment of the polyurethane molded article manufacturing method will be described with reference to Figures 25 and 26. The adhesive 22 used in step P3 of the first step S1 will be described. The adhesive 22 can be a heat-curing adhesive or a heat-melt adhesive. In step P4 of the first step S1, the base material 40 is further added to the molds 24 and 25. The second step S2 includes step P5 in which the polyurethane molding material 21 and the base material 40 are heated and pressurized to compress and mold them integrally. The compression molding in step P5 is performed by time compression for 5 to 30 minutes at a temperature of 120°C to 160°C. The pressure during compression is between 0.1 MPa and 0.5 MPa. When a wood-based material is used for the base material 40, a high-temperature compression molding method with a low moisture content in the molds 24 and 25 is preferred in order to suppress swelling of the base material 40.

[0090] The polyurethane molded articles produced by the polyurethane molded article manufacturing method of the fourth embodiment are the polyurethane molded articles 20a to 20e described with reference to Figures 6 to 10, and the sound-absorbing material 8c described with reference to Figure 12. In step P4, the order in which the base material 40 and the polyurethane molding material 21, etc. are added is appropriately determined according to the form of the base material 40.

[0091] For example, when molding the polyurethane molded body 20a shown in Figure 6, step P4 first involves placing the base material 40 into the mold 24. Next, polyurethane molding material 21 etc. is placed on top of the base material 40, and then the base material 40 is placed on top of the polyurethane molding material 21 etc. Step P5 is performed after step P4.

[0092] <Effects of Polyurethane Molding Method> The polyurethane molded article manufacturing method described above provides the following effects: Polyurethane molded articles 1, etc., can be recycled by mainly using waste materials or scraps. This reduces the environmental impact. Even if this manufacturing method does not include a preliminary step S0, the environmental impact can be reduced by using materials processed from waste materials or scraps. The main steps in manufacturing polyurethane molded articles 1, etc. are mixing polyurethane molding material 21 and adhesive 22, and heating and compression. Therefore, the polyurethane molded article manufacturing method can achieve recycling with a process that has a low environmental impact. Furthermore, since the polyurethane molded article manufacturing method uses polyurethane molding material 21 processed from rigid polyurethane foam as an example and performs compression molding, the thickness and shape can be adjusted according to the application.

[0093] In the polyurethane molded article manufacturing method, for example, the outer shell 11 of a rigid polyurethane foam cell 10 is fragmented into fragments 2, multiple adjacent fragments 2 are joined together to form a joint 3, and a communication hole 4 is formed between the fragments 2 and the joint 3. At least a portion of each fragment 2 is in a bent state, and at least a portion of each fragment 2 has an end 5 that is separated from the adjacent fragments 2. Thus, a polyurethane molded article 1 with a large sound absorption effect can be manufactured.

[0094] Furthermore, the polyurethane molded article manufacturing method may involve crushing rigid polyurethane foam and using the resulting material that has been pre-passed through a sieve with a mesh size of 2 mm. In this case, the outer shell 11 forming the cells 10 can be fragmented more uniformly to form the fragments 2. Thus, a polyurethane molded article 1a with a more uniformly enhanced sound absorption effect can be manufactured.

[0095] Furthermore, according to the polyurethane molded article manufacturing method of the third embodiment, the second step S2 includes a step P5 in which water 42 is mixed into the mold 24, and then heated and pressurized to perform compression molding. By heating and pressurizing the polyurethane molding material 21 after adding water 42 to the mold 24, heat is more easily transferred to the inside of the molded product, and the pressure molding time can be shortened. For example, the compression molding time can be shortened to about 1 / 2 to 2 / 3 of the time when water 42 is added compared to when water 42 is not added. In addition, the polyurethane molded article 1, etc., has stronger bonding force between the fragments 2, and thus has higher strength.

[0096] Furthermore, according to the polyurethane molded article manufacturing method of the fourth embodiment, in step P4 of the first step S1, the base material 40 is further added to the mold 24. As a result, the polyurethane molded article 20 can be integrally molded by bonding the polyurethane molded layer 9 and the base material 40. The polyurethane molded article 20 and sound-absorbing material 8c described with reference to Figures 6 to 10 and Figure 12 can be manufactured. As a result, the step of bonding the polyurethane molded article 20 and the sound-absorbing material 8c to the base material 40 using an adhesive after molding can be omitted. [Examples]

[0097] <Example of polyurethane molded article 1 according to the first embodiment> Next, embodiments of the present invention will be described. First, an embodiment of the polyurethane molded article 1 according to the first embodiment will be described. The embodiments of the polyurethane molded article 1 according to the first embodiment of the present invention are Example 1 and Example 2, and Comparative Examples 1 to 3 for comparison will be illustrated. Example 1 is a sound-absorbing material 8a made from the polyurethane molded article 1a of the present invention, and Example 2 is a sound-absorbing material 8b made from the polyurethane molded article 1b. Comparative Example 1 is rigid polyurethane foam before crushing. Comparative Example 2 is rock wool, and Comparative Example 3 is glass wool. Figures 1 and 2 correspond to the polyurethane molded article 1a of Example 1, Figures 3 and 4 correspond to the polyurethane molded article 1b of Example 2, and Figure 5 corresponds to Comparative Example 1. The sound-absorbing materials 8a and 8b used in the measurements here both have no surface irregularities.

[0098] Example 1 and Example 2 are formed by the molding method described in the first embodiment of the polyurethane molded body manufacturing method. In this example, a polymer adhesive having a structure derived from methylene diisocyanate is used, and the adhesive is a moisture-curing adhesive having an isocyanate group at the terminal. The conditions during molding were compression molding at a pressure of 0.2 Pa for 5 minutes. The size of the molded product is 200 mm × 200 mm × 30 mm.

[0099] As shown in FIG. 27, the size of the polyurethane molding material 21 is such that Example 1 passed through a sieve with a mesh size of 2 mm in advance, and Example 2 did not pass through a sieve with a mesh size of 2 mm in advance. In Example 2, the size of one side of the polyurethane molding material 21 is 50 mm or less. The densities of Example 1, Example 2, and Comparative Example 1 are such that Example 1, which has the smallest size of the polyurethane molding material 21, is the largest, and the comparative example is the smallest.

[0100] Next, when comparing air permeability, as shown in FIG. 27, Example 1 and Example 2 are 4.68 cm 3 / cm 2 ·s or more and 6.93 cm 3 / cm 2 ·s or less, and Comparative Example 1 is 0.23 cm 3 / cm 2 ·s. Thus, Example 1 and Example 2 have higher air permeability than Comparative Example 1. The method for measuring air permeability is as already described.

[0101] Next, when comparing thermal conductivity, as shown in FIG. 27, Example 1 is 0.0334 w / m·K, Example 2 is 0.0330 w / m·K, and Comparative Example 1 is 0.0375 w / m·K. The difference between Example 1 and Example 2 is small, but when comparing Comparative Example 1 with Example 1 and Example 2, a difference of a reproducible degree is recognized. That is, since the polyurethane molded body 1 of the present invention has a lower thermal conductivity than the hard polyurethane foam before pulverization, it has high heat insulation performance.

[0102] Next, we compare the normal incidence sound absorption coefficients with reference to Figure 28. The normal incidence sound absorption coefficient was measured according to JIS A 1405-1:2007 "Measurement of sound absorption coefficient and impedance by acoustic tubes Part 1: Standing wave ratio method". In Figure 28, A shows Example 1, B shows Example 2, and C shows Comparative Example 1. Across the entire frequency range from 0 to 6500 Hz, Examples 1 and 2 have higher normal incidence sound absorption coefficients than Comparative Example 1.

[0103] Referring to Figure 28, the frequency ranges in which the normal incidence sound absorption coefficients of Example 1 and Example 2 exhibit characteristic values ​​will be explained. The sound-absorbing material 8a using the polyurethane molded body 1a exhibits a particularly high normal incidence sound absorption coefficient in the frequency range between 500 Hz and 800 Hz, showing a value exceeding 80%. The sound-absorbing material 8b using the polyurethane molded body 1b exhibits a particularly high normal incidence sound absorption coefficient in the frequency range around 1000 Hz, showing a value exceeding 90%.

[0104] Furthermore, as shown in Figure 28, both Example 1 and Example 2 exhibit significantly higher normal incidence sound absorption coefficients of 65% or more than Comparative Example 1 in the frequency range from 2000 Hz to 6500 Hz. Therefore, although Example 1 and Example 2 have different frequency ranges in which their normal incidence sound absorption coefficients are significantly high, both demonstrate a large sound absorption effect.

[0105] Next, with reference to Figures 29 and 30, the normal incidence sound absorption coefficients for Example 1 and Comparative Examples 1 to 3 at frequencies from 100 Hz to 3100 Hz will be explained. As shown in Figure 29, the density of Comparative Example 2 is similar to that of Example 1, while that of Comparative Example 3 is lower. The thermal conductivity of Comparative Example 2 is lower than that of Example 1, while that of Example 3 is similar.

[0106] As shown in Figure 30, Example 1 exhibits significantly higher normal incidence sound absorption coefficient between 100 Hz and 1000 Hz compared to Comparative Examples 1 to 3. Generally, rock wool (Comparative Example 2) and glass wool (Comparative Example 3) are used as sound-insulating and sound-absorbing materials for residential walls. Example 1 exhibits a greater sound absorption effect than any of Comparative Examples 1 to 3 in the frequency range below 1000 Hz.

[0107] As explained above, in the case of rigid polyurethane, which is made of the same material, when the material is crushed or pulverized to a certain range, the normal incidence sound absorption coefficient is higher and the sound absorption effect is greater compared to rigid polyurethane foam. Furthermore, rigid polyurethane that has been crushed to a certain range has a higher normal incidence sound absorption coefficient in the frequency range of 100 Hz to 1000 Hz compared to rock wool or glass wool, which are made of different materials. Therefore, the polyurethane molded body 1 and the sound-absorbing material 8 made from the polyurethane molded body 1 produced by the polyurethane molded body manufacturing method of the present invention have a great sound absorption effect and a heat insulation effect.

[0108] <Example of sound-absorbing material 8 according to the second embodiment> Next, an example of the sound-absorbing material 8 according to the second embodiment will be described. Example 3 is an example of the sound-absorbing material 8 according to the second embodiment of the present invention. Comparative Example 4 is a comparative example, which is Example 1 of the polyurethane molded body 1 according to the first embodiment of the present invention. That is, it is a sound-absorbing material 8a made of polyurethane molded body 1a. As shown in Figure 11 which has already been described, Example 3 has a protrusion 34 on the first surface 31a of the sound-absorbing material 8c. The protrusion 34 is a conical protrusion 34a, with a base diameter of 10 mm and a protrusion height h of 10 mm. The thickness L of the sound-absorbing material 8c excluding the protrusion 34 is 20 mm. The distance between the centers of adjacent conical protrusions 34a is 15 mm. Comparative Example 4 is a plate material with a thickness L of 30 mm. The crushing size and density of Example 3 are the same as those of Example 1 shown in Figure 27.

[0109] Figure 31 shows the results of measuring the normal incidence sound absorption coefficient of Example 3 and Comparative Example 4 between 500 Hz and 2500 Hz. The measurement method is the same as in Figures 28 and 30. Example 3 has a normal incidence sound absorption coefficient of 65% or more between 1000 Hz and 2500 Hz. Furthermore, between 1400 Hz and 1800 Hz, the normal incidence sound absorption coefficient is 70% or more, which is higher than that of Comparative Example 4. It is particularly suitable for use in general residential buildings. Therefore, compared to Comparative Example 4, which does not have recesses 33, recesses 35 and protrusions 34, Example 3 shows an even higher normal incidence sound absorption coefficient, thus providing a greater sound absorption effect. [Explanation of symbols]

[0110] 1, 1a, 1b, 20, 20a, 20b, 20c, 20d, 20e Polyurethane molded articles 2 Fragments 3 Joint part 4 Communication hole 5 End 8, 8a, 8b, 8c, 8d, 8e, 8f, 8g, 8h, 8j Sound absorbing material 26 holes 31 sides 33, 35 recess 34 Convex part

Claims

1. A molded polyurethane article, A fragment made of polyurethane, Multiple adjacent pieces are joined together by a connecting portion, Equipped with a communication hole, The breathability is between 4.68 cm³ / cm²·s and 6.93 cm³ / cm²·s. The aforementioned fragment is At least a portion of it is refracted, A polyurethane molded body having at least a portion of its end separated from the adjacent fragment.

2. The polyurethane molded article according to claim 1, wherein the aforementioned fragment has been previously passed through a sieve with a mesh size of 2 mm.

3. The polyurethane molded article according to claim 1, wherein the aforementioned fragment has not passed through a sieve with a mesh size of 2 mm in advance.

4. A sound-absorbing material comprising a polyurethane molded body according to any one of claims 1 to 3.

5. The sound-absorbing material according to claim 4, wherein the polyurethane molded article has a normal incidence sound absorption coefficient of 50% or more in the frequency range from 400 Hz to 6500 Hz.

6. The sound-absorbing material according to claim 5, wherein the polyurethane molded article has a normal incidence sound absorption coefficient of 55% or more in the frequency range from 700 Hz to 6500 Hz.

7. The sound-absorbing material according to claim 6, wherein the polyurethane molded article has a normal incidence sound absorption coefficient of 60% or more in the frequency range from 2000 Hz to 6500 Hz.

8. The polyurethane molded body comprises a surface having recesses and / or protrusions, as described in claim 4. Sound material.

9. The sound-absorbing material according to claim 8, wherein the normal incidence sound absorption coefficient is 65% or more in the frequency range from 1000 Hz to 2500 Hz.

10. The polyurethane molded article according to any one of claims 1 to 3, wherein the fragment has a portion with a hole in it, and adjacent regions on either side of the fragment are molded to communicate with each other.

11. The polyurethane molded article according to any one of claims 1 to 3, wherein at least a portion of the end of the fragment protrudes into the communication hole and is in a free end state.

12. The polyurethane molded article is in the shape of a plate having a first surface and a second surface facing each other, The sound-absorbing material according to claim 4, wherein at least one of the first surface and the second surface has a recess and / or a protrusion.

13. The sound-absorbing material according to claim 8, wherein the recess and / or the protrusion are formed in a conical or polygonal pyramidal shape.

14. The sound-absorbing material according to claim 12, wherein the recess and / or the protrusion are formed in a conical or polygonal pyramidal shape.

15. The sound-absorbing material according to claim 8, wherein the convex portion has a shape that extends in one direction.

16. The sound-absorbing material according to claim 12, wherein the convex portion has a shape that extends in one direction.

17. The sound-absorbing material according to claim 8, wherein the convex portion is lattice-shaped.

18. The sound-absorbing material according to claim 12, wherein the convex portion is lattice-shaped.

19. The aforementioned protrusion is a plate-shaped protrusion, The sound-absorbing material according to claim 8, wherein the plate-shaped protrusions are formed in sets of several plates sandwiching the recess, and the direction in which the plate-shaped protrusions extend differs by 90 degrees between adjacent sets.

20. The aforementioned protrusion is a plate-shaped protrusion, The sound-absorbing material according to claim 12, wherein the plate-shaped protrusions are formed in sets of several plates sandwiching the recess, and the direction in which the plate-shaped protrusions extend differs by 90 degrees between adjacent sets.

21. The polyurethane molded article according to any one of claims 1 to 3, wherein the joint portion is formed by a moisture-curing adhesive.

22. A molded article comprising a polyurethane molded article according to claim 1 and a base material.

23. A method for manufacturing a polyurethane molded article according to claim 1, The first step involves crushing polyurethane foam to form a crushed product, A second step involves mixing the aforementioned crushed material with adhesive and putting it into a mold. A method for manufacturing a polyurethane molded article, comprising a third step of compression molding the aforementioned pulverized product.

24. The method for manufacturing a polyurethane molded article according to claim 23, wherein water is added to the mold in the third step.

25. The method for manufacturing a polyurethane molded article according to claim 23 or 24, wherein in the second step, a base material is further added to the mold.

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