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

Polyurethane molding and sound-absorbing material

[0001] The present invention relates to a polyurethane molded article having sound-absorbing properties and a sound-absorbing material.

[0002] Conventionally, polyurethane molded articles have been proposed for use as sound-deadening and / or heat-insulating materials in buildings, etc. For example, Patent Document 1 proposes the following porous slab. The porous slab has a resistance of 30 to 200 kg / m ３ , preferably 50 to 130 kg / m ３ and having an average particle size 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] It is stated that this provides a porous slab for a wide range of uses, for example as a support in packaging or for use in refrigerators, for example as an insulating partition between a refrigerator compartment and a freezer compartment.

[0004] Japanese Patent Application Publication No. 8-258160

[0005] However, the conventional example disclosed in Patent Document 1 has the following problems. According to Patent Document 1, the rigid polyurethane foam used is pulverized, and particularly preferably has an average particle size of 5 to 20 mm and an adhesive content of 3 to 25 wt %, preferably 5 to 12 wt %. Since the average particle size of the pulverized rigid polyurethane foam is the above-mentioned constant size, it is expected that a large proportion of the cell structure is maintained without being destroyed. Since the cell structure of rigid polyurethane foam is formed by closed cells, each cell is an independent structure, and in this case, it is expected that a large proportion of cells are not connected to adjacent cells. As a result, 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 is intended to solve the problems of the prior art, and has an object to provide a polyurethane molded article having sound-absorbing properties, and a sound-absorbing material.

[0007] The polyurethane molded article according to the first aspect of the present invention comprises polyurethane fragments, connecting portions where adjacent fragments are connected to each other, and communicating holes, and the fragments are molded in a state where at least a portion of the fragments is bent and at least a portion has an end portion that is separated from the adjacent fragments.

[0008] According to this, the polyurethane molded article has breathability because it has holes that connect the pieces and the joints. Furthermore, the pieces are connected to each other at the joints, at least a portion of which is bent, and at least a portion of which has an end that is separated from the adjacent pieces. Therefore, the polyurethane molded article attenuates sound vibrations and has a sound-absorbing effect.

[0009] The polyurethane molding may also be such that the pieces have been passed through a sieve with 2 mm openings in advance. In this case, the polyurethane pieces have been passed through a sieve with 2 mm openings in advance, resulting in a high density after compression molding and more uniform formation of the pieces, joints, and communicating holes. This results in a stable sound absorption effect.

[0010] The polyurethane molding may be such that the pieces have not passed through a sieve with 2 mm openings in advance. In this case, the polyurethane pieces have a low density after compression molding, making it possible to reduce the weight. Furthermore, the sound absorption effect can be further improved.

[0011] A sound-absorbing material according to a second aspect of the present invention includes the polyurethane molded article. As a result, a sound-absorbing material with a high sound-absorbing effect can be provided, since the polyurethane molded article has sound-absorbing properties.

[0012] The polyurethane molding 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] The polyurethane molding may have a normal incidence sound absorption coefficient of 55% or more in the frequency range from 700 Hz to 6500 Hz, in which case the sound-absorbing material exhibits a greater sound-absorbing effect in the frequency range from 700 Hz to 6500 Hz.

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

[0015] The polyurethane molding of the sound-absorbing material may have a surface with recesses and / or protrusions. In this case, the recesses and / or protrusions increase the surface area of ​​the polyurethane molding, thereby achieving a greater sound-absorbing effect.

[0016] The sound absorbing material may have a normal incidence sound absorption coefficient of 65% or more in the frequency range from 1000 Hz to 2500 Hz, in which case the sound absorbing material exhibits an even greater sound absorbing effect in the frequency range from 1000 Hz to 2500 Hz.

[0017] 1 is a micrograph showing a polyurethane molded product 1a of a first embodiment in the polyurethane molded product 1 of the present invention. FIG. 2 is a micrograph showing an enlargement of a portion of the polyurethane molded product 1a shown in FIG. 1. FIG. 3 is a micrograph showing a polyurethane molded product 1b of a second embodiment in the polyurethane molded product 1 of the present invention. FIG. 4 is a micrograph showing an enlargement of a portion of the polyurethane molded product 1b shown in FIG. 5. FIG. 6 is a micrograph showing the polyurethane molded product 1 of the present invention before pulverizing the rigid polyurethane foam. FIG. 7 is a micrograph showing a polyurethane molded product 20a of a first embodiment in the polyurethane molded product 20 of the present invention, where (a) is a perspective view and (b) is a cross-sectional view cut along the longitudinal direction. FIG. 8 is a diagram showing a polyurethane molded product 20b of a second embodiment in the polyurethane molded product 20 of the present invention, where (a) is a perspective view and (b) is a cross-sectional view cut along the longitudinal direction. FIG. 9 is a diagram showing a polyurethane molded product 20c of a third embodiment in the polyurethane molded product 20 of the present invention, where (a) is a perspective view and (b) is a cross-sectional view cut along the longitudinal direction. FIG. 10 is a diagram showing a polyurethane molded product 20d of a fourth embodiment in the polyurethane molded product 20 of the present invention, where (a) is a perspective view and (b) is a cross-sectional view cut along the longitudinal direction. 11 shows a fifth embodiment of a polyurethane molded body 20e of the present invention, where (a) is a perspective view and (b) is a longitudinal cross-sectional view. (a) is a perspective view of a sound-absorbing material 8c of the present invention, showing a case where the convex portion 34 is a conical convex portion 34a. (b) to (d) are partial enlarged views viewed in the F direction of (a). (b) shows a case where the tip of the conical convex portion 34a is a hemispherical arc-shaped portion, (c) shows a case where the tip is flat, and (d) shows a case where the tip is pointed. Compared to FIG. 11 , the sound-absorbing material 8c includes a substrate 40. (a) shows a case where the polyurethane molded layer 9 sandwiches the substrate 40, and (b) shows a case where the substrate 40 is provided on the bottom side. (a) is a perspective view showing the sound-absorbing material 8c of the present invention, in which the convex portion 34 is a quadrangular pyramidal convex portion 34b, (b) to (d) are partial enlarged views when viewed in the G direction of (a), in which (b) shows the case where the tip of the quadrangular pyramidal convex portion 34b is a hemispherical arc shape, (c) shows the case where the tip is flat, and (d) shows the case where the tip is pointed.1A is a perspective view of a sound-absorbing material 8c of the present invention, showing a case where the convex portions 34 are wave-shaped convex portions 34c; (b) to (d) are partial enlarged views as viewed in the J direction of (a); (b) shows a case where the tips of the wave-shaped convex portions 34c are semicircular arc-shaped; (c) shows a case where the tips are flat; and (d) shows a case where the tips are pointed. 1B is a perspective view of a sound-absorbing material 8c of the present invention, showing a case where the convex portions 34 are lattice-shaped convex portions 34d. 1B is a perspective view of a sound-absorbing material 8c of the present invention, showing a case where the convex portions 34 are plate-shaped convex portions 34e; (b) to (d) are partial enlarged views as viewed in the K direction of (a); (b) shows a case where the tips of the plate-shaped convex portions 34e are semicircular arc-shaped; (c) shows a case where the tips are flat; and (d) shows a case where the tips are pointed. 1A is a perspective view of a sound-absorbing material 8d of the present invention, showing a case in which a recess 35 is formed, and (b) to (d) are partial enlarged views (cross-sectional views) as viewed in the M direction of (a), where (b) shows a case in which the tip of the recess is a hemispherical arc shape, (c) shows a case in which the tip is flat, and (d) shows a case in which the tip is pointed. FIG. 1B is a perspective view of a sound-absorbing material 8e of the present invention, showing a case in which a protrusion 34 and a recess 35 are formed. FIG. 1C is a diagram illustrating a first embodiment of a method for producing a polyurethane molded body 1 and a sound-absorbing material 8 of the present invention, showing a perspective view schematically illustrating the production steps. FIG. 1D is a flowchart illustrating each step of the first embodiment of the method for producing a polyurethane molded body of the present invention. FIG. 1E is a diagram illustrating a second embodiment of a method for producing a polyurethane molded body 1 and a sound-absorbing material 8 of the present invention, showing a perspective view schematically illustrating the production steps. FIG. 1F is a flowchart illustrating each step of the second embodiment of the method for producing a polyurethane molded body of the present invention. FIG. 1G is a diagram illustrating a third embodiment of a method for producing a polyurethane molded body 1 and a sound-absorbing material 8 of the present invention, showing a perspective view schematically illustrating the production steps. FIG. 1G is a flowchart illustrating each step of the third embodiment of the method for producing a polyurethane molded body of the present invention. 1 is a diagram illustrating a fourth embodiment of the method for producing a polyurethane molded body 20 and a sound-absorbing material 8c of the present invention, and is a perspective view schematically illustrating the production process. 2 is a flowchart showing each step of the fourth embodiment of the method for producing a polyurethane molded body of the present invention. 3 is a diagram illustrating measurement results of Example 1, Example 2, and Comparative Example 1.1 shows comparative data obtained by measuring the normal incidence sound absorption coefficients of Example 1, Example 2, and Comparative Example 1 in a frequency range of 500 Hz or higher. 2 shows measurement results for Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3. 3 shows comparative data obtained by measuring the normal incidence sound absorption coefficients of Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 in a frequency range of 100 Hz to 3100 Hz. 4 shows comparative data obtained by measuring the normal incidence sound absorption coefficients of Example 3 and Comparative Example 4 in a frequency range of 500 Hz to 2500 Hz.

[0018] Hereinafter, a polyurethane molded body 1, a polyurethane molded body 20, a sound-absorbing material 8, and a method for manufacturing a polyurethane molded body that embody the present invention will be described with reference to the drawings. Note that the description of the embodiment of the invention and the drawings referred to are used to explain the technical features that can be adopted by the present invention. The present invention is not limited to these. The configuration of the device shown in the drawings is not intended to be limiting, but is merely an illustrative example.

[0019] <Configuration common to polyurethane molded body 1, etc. according to the first aspect> A polyurethane molded body 1 and a polyurethane molded body 20 according to the first aspect of the present invention will be described. Hereinafter, the polyurethane molded body 1 and the polyurethane molded body 20 will be collectively referred to as the polyurethane molded body 1, etc. Each embodiment will be described later, but first the common configuration will be described. As shown in Figs. 1 to 4, the polyurethane molded body 1, etc. comprises polyurethane fragments 2, connecting portions 3 at which adjacent polyurethane fragments 2 are connected to one another, and communication holes 4. The fragments 2 are molded so that at least a portion of them is bent and at least a portion of them has an end portion 5 separated from adjacent fragments 2.

[0020] As an example, the fragment 2 is a fragment of the outer shell 11 forming the cells 10 of a rigid polyurethane foam. Figures 1 to 4 are micrographs of a material such as a polyurethane molded body 1, which is obtained by crushing a rigid polyurethane foam and then compressing it. The material of the polyurethane molded body 1 is not limited to rigid polyurethane, but may be any polyurethane material. Furthermore, the polyurethane molding material 21, which is the polyurethane fragment 2, does not need to be crushed, and may be of a size as described below. As shown in Figure 5, the rigid polyurethane foam is a polyurethane foam having cells 10 with an independent structure.

[0021] 2 and 4, the communicating holes 4 look like black shadows, but they are not closed by the fragments 2, and the communicating holes 4 are connected to each other while intertwining inside the polyurethane molded body 1, etc. The fragments 2 are not flat, but are bent as if irregularly folded, and are integrally molded by joining with other adjacent fragments 2 at joining parts 3.

[0022] As shown in Figures 1 to 4, for example, a polyurethane molded product 1 is obtained by crushing the outer shells 11 of cells 10 of a rigid polyurethane foam to form fragments 2, which are then compression molded while forming joints 3 with an adhesive 22. The manufacturing methods will be described later. Also, adhesives 22 suitable for each manufacturing method will 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, before being crushed, rigid polyurethane foam has cells 10 surrounded by an outer shell 11. Each cell 10 is independent, and compared to after being crushed, the cells 10 are clearly visible, making it difficult for adjacent cells 10 to communicate with each other. Furthermore, before being crushed, the cells 10 are surrounded by the outer shell 11 over a wide area. In contrast, in the polyurethane molded body 1 shown in Figures 1 and 3, the outer shell 11 is divided and compressed, resulting in the cells 10 being crushed. The outer shell 11 is divided and fragmented, forming fragments 2, which are further compressed and irregularly bent. Furthermore, the fragments 2 are connected by bonding portions 3 formed by an adhesive 22, forming communicating holes 4 and further integrating them.

[0024] As shown in FIGS. 2 and 4, at least a part of the end 5 of the piece 2 is formed in a pleated shape, protruding into the communicating hole 4, and is in a state of being an unconstrained free end.

[0025] 2 to 4, each fragment 2 has a defect 6 in at least one portion. The defect 6 is a blackened portion that resembles a hole in a portion of the fragment 2. Unlike the communication hole 4, the defect 6 is formed in one fragment 2. The defect 6 allows adjacent regions sandwiching the fragment 2 to communicate with each other.

[0026] The breathability of the polyurethane molding 1 etc. is 4.68 cm ３ / cm ２ ・6.93 cm³ / cm³ for s or more ２ The breathability is measured based on "JIS L 1096 Fabric Testing Methods for Woven and Knit Fabrics." The breathability is achieved by the through holes 4 and the missing portions 6.

[0027] Next, the normal incidence sound absorption coefficient of the polyurethane molding 1, etc. will be described with reference to Figs. 28 and 30. In Figs. 28 and 30, A and B correspond to the polyurethane molding 1, etc. The polyurethane molding 1, etc. has a normal incidence sound absorption coefficient of 50% or more in the frequency range from 400 Hz to 6500 Hz. As shown in Fig. 28, the polyurethane molding 1, etc. has a normal incidence sound absorption coefficient of 55% or more in the frequency range from 700 Hz to 6500 Hz. Furthermore, the polyurethane molding 1, etc. has a normal incidence sound absorption coefficient of 60% or more in the frequency range from 2000 Hz to 6500 Hz. The method for measuring the normal incidence sound absorption coefficient and detailed measurement results will be described in the explanation of each embodiment and in the examples.

[0028] <Effects of the Configuration Common to the Polyurethane Molded Product 1, etc. According to the First Aspect> The configuration common to the polyurethane molded product 1, etc. described above provides the following effects. As shown in Figures 1 to 4, the polyurethane molded product 1, etc., has communication holes 4 that communicate between the pieces 2 and the joints 3, and is therefore breathable. Furthermore, the pieces 2 are joined to each other at the joints 3, and at least a portion of them is in a bent state, with at least a portion having an end 5 that is separated from the adjacent pieces 2. Therefore, the polyurethane molded product 1, etc., attenuates sound vibrations and provides a sound-absorbing effect.

[0029] Furthermore, the ends 5 of the pieces 2 are formed in pleats and protrude into the communication holes 4, which facilitates damping of sound vibrations and provides a better sound absorption effect.

[0030] Furthermore, since the pieces 2 have not only the through holes 4 but also the missing portions 6 in some places, the breathability can be further improved, and the transmitted sound vibrations are dispersed over a wider range, resulting in a greater sound absorption effect.

[0031] Furthermore, the polyurethane molded body 1 etc. has an appropriate range of breathability, and therefore exhibits sound absorption and heat insulation effects.

[0032] Next, the sound absorption effect of the polyurethane molding 1 and the like will be described. The polyurethane molding 1 and the like have a normal incidence sound absorption coefficient of 50% or more in the frequency range from 400 Hz to 6500 Hz, so they exhibit a sound absorption effect over a wide frequency range. Furthermore, the polyurethane molding 1 and the like have a normal incidence sound absorption coefficient of 55% or more in the frequency range from 700 Hz to 6500 Hz, so they exhibit a greater sound absorption effect in the frequency range from 700 Hz to 6500 Hz. Furthermore, the normal incidence sound absorption coefficient is 60% or more in the frequency range from 2000 Hz to 6500 Hz, so they exhibit an even greater sound absorption 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 Aspect> Next, a polyurethane molded body 1a which is a first embodiment of the polyurethane molded body 1 and a polyurethane molded body 1b which is a second embodiment will be described with reference to Fig. 1 to Fig. 4. In the polyurethane molded body 1a of the first embodiment, the polyurethane molding material 21, which is a polyurethane fragment 2, has been passed through a sieve with a mesh size of 2 mm in advance. In contrast, in the polyurethane molded body 1b of the second embodiment, the polyurethane molding material 21, which is a fragment 2, has not been passed through a sieve with a mesh size of 2 mm in advance.

[0034] The polyurethane molding material 21 is, for example, a pulverized rigid polyurethane foam, and the polyurethane molding body 1a and the polyurethane molding body 1b have different particle sizes. The polyurethane molding material 21 may be formed by a method other than pulverization.

[0035] FIGS. 1 and 2 are micrographs showing a polyurethane molded body 1a, and FIGS. 3 and 4 are micrographs showing a polyurethane molded body 1b. Both are, as an example, compressed using a polyurethane molding material 21 made by pulverizing rigid polyurethane foam. FIGS. 1 and 3 are at the same magnification. Comparing FIGS. 1 and 3, as shown in FIG. 1, in the polyurethane molded body 1a, a large proportion of the outer shell 11 of the cells 10 is fragmented, with most of the cells being fragmented into small fragments 2. The fragments 2 are joined by the connecting portions 3, resulting in the formation of approximately uniform apparent cells 12 containing communicating holes 4. Here, the apparent cells 12 refer to the areas that appear cellular because part of the outer shell 11 is formed by the fragments 2. However, due to the unclear outline, the apparent cells 12 are provisionally referred to as "apparent." The apparent cells 12 shown in FIGS. 1 to 4 show only approximate outlines.

[0036] 1 and 2, the polyurethane molded body 1a has many of its end portions 5 formed in pleats, compared to the polyurethane molded body 1b, and protrudes into the communicating holes 4. The fragments 2 are crushed and bent, forming fold lines 7.

[0037] As shown in Figure 3, polyurethane molded body 1b has some remaining cells 10 and wider spacing between adjacent communicating holes 4 than polyurethane molded body 1a. The mixture of remaining cells 10 and apparent cells 12 where joints 3 connect fragments 2 results in unevenness. However, although polyurethane molded body 1b has a smaller proportion of apparent cells 12 than polyurethane molded body 1a, outer shells 11 of cells 10 are separated to form fragments 2, and joints 3 and communicating holes 4 are formed. Furthermore, missing portions 6 are formed in some of the fragments 2.

[0038] <Effects of Each Embodiment of the Polyurethane Molded Body 1 According to the First Aspect> As explained 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, have the following effects. The characteristic values ​​of the polyurethane molded body 1a and the polyurethane molded body 1b will be explained in the examples below, but both have both heat insulation and sound absorption properties.

[0039] The polyurethane molded body 1a has a smaller material volume before compression than the polyurethane molded body 1b, and therefore has a higher density after compression molding, and the pieces 2, the joints 3, and the communication holes 4 are more uniformly formed. Therefore, the polyurethane molded body 1a has more stable heat insulation and sound absorption properties even when partially cut out and used.

[0040] Furthermore, the polyurethane molded body 1b has a low density after compression molding, allowing for weight reduction. Furthermore, the sound absorbing effect can be further enhanced. The structure and effects of the polyurethane molded body 1 described above are also the same as those of the polyurethane molded layer 9 in the polyurethane molded body 20 described below.

[0041] <Configuration and Effects of the Polyurethane Molded Body 20 According to the First Aspect> Next, the polyurethane molded body 20 according to the first aspect of the present invention will be described. As shown in FIGS. 6 to 10 , the polyurethane molded body 20 includes a polyurethane molded layer 9 and a substrate 40. The polyurethane molded layer 9 corresponds to the polyurethane molded body 1 described with reference to FIGS. 1 to 4 , and includes polyurethane fragments 2, connecting portions 3 where adjacent fragments 2 are connected to each other, and communication holes 4. The fragments 2 are molded in a state in which at least a portion is bent and at least a portion has an end portion 5 separated from adjacent fragments 2. The polyurethane molded layer 9 and the substrate 40 are at least partially bonded to each other. The polyurethane molded layer 9 and the substrate 40 are integrally molded using a polyurethane molded body manufacturing method described below. Alternatively, the polyurethane molded layer 9 and the substrate 40 are bonded with an adhesive 22. The substrate 40 includes, for example, MDF. MDF is a medium-density fiberboard, and refers to a board material. Although MDF is used in this example, other materials can be used for the base material 40 as long as they have a reinforcing effect.

[0042] The polyurethane molded body 20 according to the first aspect of the present invention as described above has the following common effects in all embodiments. In the polyurethane molded body 20, the polyurethane molded layer 9 and the substrate 40 are at least partially bonded to each other, and therefore the strength is increased by the substrate 40. Furthermore, the polyurethane molded body 20 can have improved sound insulation or sound absorption properties depending on the form. Therefore, the polyurethane molded body 20 can be used as a heat insulating material and / or a sound absorbing material.

[0043] Next, various embodiments of the polyurethane molded body 20 will be described. Referring to FIG. 6 , a polyurethane molded body 20a, which is a first embodiment of the polyurethane molded body 20, will be described. The polyurethane molded layer 9 of the polyurethane molded body 20a has a top surface 9a and a bottom surface 9b covered with a substrate 40. The side surfaces may be exposed. As shown in FIG. 6( b), the polyurethane molded body 20a is integrally molded such that the substrate 40 is bonded to the top surface 9a and the bottom surface 9b of the polyurethane molded layer 9. Alternatively, the substrate 40 may be bonded to the top surface 9a and the bottom surface 9b of the polyurethane molded layer 9. While the polyurethane molded body 20a and the polyurethane molded body 20b described next have been described as having a three-layer structure in the thickness direction, a two-layer structure consisting of the polyurethane molded layer 9 and the substrate 40 may also be used.

[0044] The polyurethane molded body 20a, which is the first embodiment of the polyurethane molded body 20 described above, has the following advantages. As shown in Fig. 6, in the polyurethane molded body 20a, the polyurethane molded layer 9 is sandwiched between the base materials 40 at the top surface 9a and the bottom surface 9b. Therefore, the polyurethane molded body 20a has high strength. Furthermore, since the polyurethane molded layer 9 is sandwiched between the base materials 40, the polyurethane molded body 20a has sound insulation properties.

[0045] Next, a polyurethane molded body 20b, which is a second embodiment of the polyurethane molded body 20, will be described with reference to Figure 7. The base material 40 of the polyurethane molded body 20b has a top surface 40a and a bottom surface 40b covered with a polyurethane molded layer 9. The side surfaces may be exposed. As shown in Figure 7(b), the polyurethane molded body 20b is integrally molded such that the polyurethane molded layer 9 is bonded to the top surface 40a and the bottom surface 40b of the base material 40. Alternatively, the polyurethane molded body 20b may have the polyurethane molded layer 9 bonded to the top surface 40a and the 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, has the following advantages. As shown in Fig. 7, in the polyurethane molded body 20b, the top surface 40a and the bottom surface 40b of the base material 40 are covered with the polyurethane molded layer 9. Therefore, the polyurethane molded body 20b has sound absorbing properties. In addition, the base material 40 increases the strength.

[0047] Next, referring to Figure 8, a polyurethane molded body 20c, which is a third embodiment of the polyurethane molded body 20, will be described. The outer periphery of the substrate 40 of the polyurethane molded body 20c is covered with a polyurethane molded layer 9. For example, the substrate 40 has a rectangular parallelepiped shape. As shown in Figure 8(b) , the polyurethane molded body 20c has the substrate 40 covered with 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 also shows that the substrate 40 is covered with 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, has the following effects. As shown in Fig. 8, in the polyurethane molded body 20c, the outer periphery of the substrate 40 is covered with 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, referring to FIG. 9 , a polyurethane molded body 20d, which is a fourth embodiment of the polyurethane molded body 20, will be described. As shown in FIG. 9 , the polyurethane molded layer 9 of the polyurethane molded body 20d is covered on its outer periphery by a substrate 40. As shown in FIG. 9( b), the polyurethane molded body 20d has the polyurethane molded layer 9 covered by the substrate 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 also covered by the substrate 40 in the thickness direction and the width direction. As shown in the example of FIG. 9( b), the substrate 40 includes a bottom box 40c and a lid 40d, and the polyurethane molded body 20b has the polyurethane molded layer 9 integrally molded inside the substrate 40. Alternatively, the polyurethane molded layer 9 may be bonded to the inside of the substrate 40.

[0050] The polyurethane molded body 20d, which is the fourth embodiment of the polyurethane molded body 20 described above, has the following advantages. As shown in Fig. 9, in the polyurethane molded body 20d, the polyurethane molded layer 9 has an increased strength because its outer periphery is covered by the substrate 40. In addition, the polyurethane molded layer 9 can be prevented from falling off.

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

[0052] The polyurethane molded body 20e, which is the fifth embodiment of the polyurethane molded body 20 described above, has the following advantages. As shown in FIG. 10 , in the polyurethane molded body 20e, the polyurethane molded layer 9 has its side surfaces covered by the substrate 40, its top surface 9a and bottom surface 9b exposed, and its side surfaces covered by the substrate 40. This increases the strength of the polyurethane molded body 20e. Furthermore, because the top surface 9a and bottom surface 9b of the polyurethane molded layer 9 are exposed, the polyurethane molded layer 9 has sound-absorbing properties. Furthermore, the polyurethane molded layer 9 can be prevented from falling off from the side surfaces.

[0053] <Configuration and Effects of Sound-Absorbing Material 8 According to the Second Aspect of the Present Invention> Next, the sound-absorbing material 8 according to the second aspect of the present invention will be described. As shown in FIG. 19(c), the sound-absorbing material 8 may be a polyurethane molded body 1 used as is, or may be fitted into a predetermined frame or the like. Furthermore, as will be described later, as shown in FIGS. 11 to 18, the sound-absorbing material 8 may have a surface with concave and / or convex portions, and there are no particular restrictions on shape or size. First, with reference to FIGS. 28 and 30, the relationship between frequency and normal incident sound absorption coefficient in the sound-absorbing material 8 will be described. As shown in FIG. 28, the sound-absorbing material 8 made of the polyurethane molded body 1 has a normal incident sound absorption coefficient of 55% or more in the frequency range from 700 Hz to 6500 Hz. Furthermore, in the frequency range from 2000 Hz to 6500 Hz, the normal incident sound absorption coefficient is 60% or more. In FIG. 28, A represents a polyurethane molded body 1a, B represents a polyurethane molded body 1b, and C represents a rigid polyurethane foam.

[0054] As shown in Fig. 30, the sound-absorbing material 8 made of polyurethane molding 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 rises sharply from 100 Hz, peaking around 700 Hz to 800 Hz. In Fig. 30, A and C are the same as Fig. 28, D represents rock wool, and E represents glass wool.

[0055] As described above, the sound-absorbing material 8 made of polyurethane molding 1 exhibits a sharp increase in 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. Human conversational voices are generally considered to be in the range from 250 Hz to 4000 Hz. The sound-absorbing material 8 exhibits a sound-absorbing effect for human conversational voices. Furthermore, the sound-absorbing material 8 exhibits a normal incidence sound absorption coefficient of 55% or more in the frequency range from 700 Hz to 6500 Hz, further enhancing the sound-absorbing effect. Furthermore, the sound-absorbing material 8 exhibits a greater sound-absorbing effect in the high-frequency range from 2000 Hz to 6500 Hz. The normal incidence sound absorption coefficient shown in FIG. 28 will be described in detail in the Examples. The normal incidence sound absorption coefficient described above is a measurement value for a sound-absorbing material 8 having a substantially rectangular parallelepiped flat plate shape. A case in which the surface has irregularities will be described next.

[0056] <Explanation of Sound-Absorbing Material 8 Having Concave and Convex Shape> Next, with reference to FIGS. 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 surfaces 31 with recesses 33 and / or protrusions 34. Sound-absorbing materials 8h and 8j have surfaces 31 with recesses 35 and / or protrusions 34. As an example, as shown in FIG. 11 and other figures, a case will be described in which sound-absorbing material 8 has a predetermined thickness and includes a first surface 31a and a second surface 31b facing each other. At least one of first surface 31a and second surface 31b has recesses 33 and / or protrusions 34, or recesses 35 and / or protrusions 34. Here, recesses 33 refer to valleys between protrusions 34 as shown in FIG. 14 and other figures, and recesses 35 refer to recesses formed from surface 31 as shown in FIG. 17 and other figures.

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

[0058] Referring to FIG. 11 , the sound-absorbing material 8c will be described. The sound-absorbing material 8c has conical convex portions 34a as its protrusions. As shown in FIG. 11( a), the conical convex portions 34a are arranged in a grid pattern. The tips of the conical convex portions 34a may be hemispherically rounded as shown in FIG. 11( b), flat as shown in FIG. 11( c), or pointed as shown in FIG. 11( d). The relationship between the thickness L and the convex portion height h can be set arbitrarily. The thickness L may be equal to or greater than the convex portion height h. This also applies to the other convex portions 34 described below. The spacing between adjacent conical convex portions 34a may be equal or random. Note that while the convex portions 34 shown in FIG. 11 are conical convex portions 34a, the convex portions 34 may also be cylindrical. Furthermore, in Example 4 described below, the convex portions 34 are conical convex portions 34a as shown in FIG. 11.

[0059] The example shown in Figure 12 differs from the example shown in Figure 11 in that a polyurethane molded layer 9, which is part of the sound-absorbing material 8c, is bonded to a substrate 40. The example shown in Figure 12(a) shows a case in which the substrate 40 is sandwiched between a polyurethane molded layer 9 having conical protrusions 34a in the thickness direction and an underlying polyurethane molded layer 9. The example shown in Figure 12(b) shows a case in which the substrate 40 is the underlying layer of a polyurethane molded layer 9 having conical protrusions 34a in the thickness direction.

[0060] A sound-absorbing material 8d will be described with reference to FIG. 13 . The sound-absorbing material 8d has protrusions 34 formed as square pyramidal protrusions 34b. As shown in FIG. 13( a), the square pyramidal protrusions 34b are arranged in a lattice pattern, similar to the example shown in FIG. 11 . The tips of the square pyramidal protrusions 34b may be hemispherically rounded as shown in FIG. 13( b), flat as shown in FIG. 13( c), or pointed as shown in FIG. 13( d). The spacing between adjacent square pyramidal protrusions 34b may be equal or random. While the example shown in FIG. 13 has protrusions 34b as square pyramidal protrusions, 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 wavy convex portions 34c that are continuously formed in one direction and have a wave-like shape with concave portions 33 sandwiched between them, as shown in Figure 14(a). The intervals between adjacent wavy convex portions 34c may be equal or random. Note that in the example shown in Figure 14, adjacent wavy convex portions 34c are formed independently of each other, but they may also be connected by a smooth curve with the concave portion 33 sandwiched between them. The tips of the wavy convex portions 34c may be semicircularly rounded 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 a case in which the convex portions 34 are lattice-shaped convex portions 34d. The wave-shaped convex portions 34c described with reference to Figure 14 are formed in a lattice pattern so as to intersect with each other. The intervals between adjacent lattice-shaped convex portions 34d may be equal or random. In the example shown in Figure 15, adjacent lattice-shaped convex portions 34d are formed independently of each other, but they may also be connected by a smooth curve with a concave portion 33 in between. The tip shape of the lattice-shaped convex portions 34d is the same as that of the wave-shaped convex portions 34c described with reference to Figure 14.

[0063] The sound-absorbing material 8g will be described with reference to FIG. 16 . The sound-absorbing material 8g shows a case in which the protrusions 34 are plate-shaped protrusions 34e. As shown in FIG. 16( a), the plate-shaped protrusions 34e are formed in groups of several sheets, sandwiching a recess 33 therebetween, and the extension directions of the plate-shaped protrusions 34e between adjacent groups are formed so as to differ by 90 degrees. The spacing between adjacent plate-shaped protrusions 34e may be equal or random. The gaps between each group may also be equal or random. The tips of the plate-shaped protrusions 34e may be semicircularly rounded as shown in FIG. 16( b), flat as shown in FIG. 16( c), or pointed as shown in FIG. 16( d).

[0064] The sound-absorbing material 8h will be described with reference to FIG. 17 . The sound-absorbing material 8h is shown in a case where only recesses 35 are formed. As shown in FIG. 17( a), the recesses 35 are recessed from the first surface 31a. The recesses 35 are conical, for example. The depth d of the recesses 35 may be the same as or different from the height h of the protrusions 34. Alternatively, the recesses 35 may be cylindrical, polygonal prism-shaped, or polygonal pyramid-shaped. While the recesses 35 are arranged in a lattice pattern, they may also be arranged randomly. The tips of the recesses 35 may be hemispherically rounded as shown in FIG. 17( b), flat as shown in FIG. 17( c), or pointed as shown in FIG. 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 alternately arranged in a lattice pattern. The conical protrusions 34a protrude from the first surface 31a, and the recesses 35 are recessed from the first surface 31a. While the conical protrusions 34a and recesses 35 are arranged in a lattice pattern, they may also 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. Sound-absorbing material 8c will be described as a representative example. While detailed explanations will be given in the examples below, Example 3 shown in FIG. 31 is sound-absorbing material 8c. Sound-absorbing material 8c has a normal incident sound absorption coefficient of 65% or more between 1000 Hz and 2500 Hz. Furthermore, between 1400 Hz and 1800 Hz, the normal incident sound absorption coefficient is 70% or more.

[0067] In the above example, the convex portions 34, concave portions 33, and concave portions 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. Also, the convex portions 34, concave portions 33, and concave portions 35 may have different shapes on the first surface 31a and the second surface 31b. Also, while the sound-absorbing material 8 is plate-shaped, this is not a limitation. For example, the sound-absorbing material 8 may be spherical, polygonal pyramidal, polygonal prism-shaped, conical, or any other shape.

[0068] <Effects of sound-absorbing material having an uneven surface> The sound-absorbing materials 8c to 8j described above have the following effects. The sound-absorbing materials 8c to 8j have an increased surface area of ​​the polyurethane molded body 1 and the like due to the recesses 33, etc. and / or the protrusions 34, and therefore have a greater sound-absorbing effect. That is, the surface area of ​​the polyurethane molded body 1 is increased by at least one of the recesses 33, 35, and protrusions 34, and therefore have a greater sound-absorbing effect. When the area of ​​the polyurethane molded body 1 is increased, the number of paths for air that transmits sound vibrations increases, and the sound-absorbing effect is greater than when the surface is flat and has no recesses or protrusions.

[0069] Furthermore, in the case of sound-absorbing materials 8c shown in Fig. 11 through 8f shown in Fig. 15 and sound-absorbing material 8e shown in Fig. 18, the sides of the protrusions 34 are inclined at a predetermined angle relative to the thickness direction, allowing air that transmits sound to enter from multiple angles. Furthermore, in the case of sound-absorbing material 8h shown in Fig. 17 and sound-absorbing material 8j shown in Fig. 18, the inner surfaces of the recesses 35 are inclined at a predetermined angle, allowing air that transmits sound to enter from multiple angles. Therefore, sound-absorbing materials 8c through 8j provide a greater sound-absorbing effect.

[0070] Furthermore, for example, when the surface 31 having the protrusions 34 is used in a state where it is in contact with another member such as a wall surface, air can pass through between the protrusions 34, ensuring breathability.

[0071] Furthermore, the sound absorbing material 8c described with reference to FIG. 12 is a combination of the polyurethane molded layer 9 and the substrate 40, and therefore exhibits the same effects as the polyurethane molded body 20a and the like already described.

[0072] 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 has a large sound absorption effect between 1000 Hz and 2500 Hz. Furthermore, the sound-absorbing material 8c has an even greater sound absorption effect between 1400 Hz and 1800 Hz.

[0073] <<Explanation of Polyurethane Molded Body Manufacturing Method>> Next, with reference to FIGS. 19 to 26, a polyurethane molded body manufacturing method according to a third aspect of the present invention will be described. The polyurethane molded body manufacturing method is a method for manufacturing a polyurethane molded body 1, a polyurethane molded body 20, and a sound-absorbing material 8. First, steps common to all polyurethane molded body manufacturing methods will be described. The polyurethane molded body manufacturing method may include a preliminary step S0, prior to the first step S1, in which polyurethane foam is pulverized to form polyurethane fragments 2 and a polyurethane molding material 21. The preliminary step S0 is optional. That is, the preliminary step S0 may be incorporated into the series of manufacturing steps, or the manufacturing process may start from the first step S1, which will be described later, using polyurethane molding material 21 that has already been pulverized. The polyurethane foam is, for example, a rigid polyurethane foam.

[0074] 20, 22, 24, and 26, when the preliminary step S0 is provided, 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] A case in which a preliminary step S0 is included will be described. The polyurethane molding material 21 is, for example, a rigid polyurethane foam. Before being pulverized, the rigid polyurethane foam has cells 10 surrounded by an outer shell 11, as shown in FIG. 5 . For example, the rigid polyurethane foam used is one discarded as industrial waste or scrap material generated during the production process. In this case, as shown in the examples of FIGS. 19 and 20 , the polyurethane molded product manufacturing method includes a rigid polyurethane foam recovery step P1 for recovering materials and a rigid polyurethane foam pulverization step P2.

[0076] Step P2 is a rigid polyurethane foam pulverization process in which the outer shell 11 forming the cells 10 of the rigid polyurethane foam is fragmented to form fragments 2. In step P2, the rigid polyurethane foam is pulverized to a predetermined size. As shown in Example 1 described below, the polyurethane molding material 21 may be prepared by pulverizing rigid polyurethane foam and passing it through a 2 mm mesh sieve. As already explained, the state of the fragments 2, joints 3, communicating holes 4, and missing portions 6 after molding varies depending on the size of the pulverized chips. Note that hereinafter, the molding material used in this manufacturing method is referred to as polyurethane molding material 21, including cases where the rigid polyurethane foam is pre-processed to a predetermined size without being pulverized. Note that if the rigid polyurethane foam is not waste, step P1 is omitted. Furthermore, if the polyurethane molding material 21 is pre-pulverized or has a predetermined fine size, step P2 of the rigid polyurethane foam pulverization process is omitted.

[0077] If the method for producing a polyurethane molded body includes a preliminary step S0, it proceeds to a first step S1 after the preliminary step S0. If the method does not include the preliminary step S0, the method starts from the first step S1 without the preliminary step S0. As shown in Figure 19 and other figures, the method includes a first step S1 in which a polyurethane molding material 21 and an adhesive 22 are mixed and poured into molds 24, 25, and a second step S2 in which the mixture is compression molded in the molds 24, 25. In the second step S2, joints 3 where adjacent pieces 2 are joined to each other and communication holes 4 are formed. At least some of the pieces 2 form ends 5 that are separated from adjacent pieces 2.

[0078] The first step S1 will now be described. As shown in FIG. 19 and other figures, the first step S1 includes steps P3 and P4. As shown in the example of FIG. 19(a), in step P3, the polyurethane molding material 21 and the adhesive 22 are poured into a mixing container 41, and the mixing container 41 is vibrated in multiple directions to mix them. The adhesive 22 is selected and used appropriately for each embodiment, which will be described later. Step P4 differs slightly depending on the embodiment. In the first to third embodiments, step P4 is a step of pouring the polyurethane molding material 21 and the like into the molding dies 24, 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 polyurethane molding material 21 mixed with adhesive 22 is poured into molds 24 and 25 and then compression-molded, and a step P6 in which the molded product is removed. Step P5 differs depending on the embodiment. Note that sound-absorbing material 8c shown in FIG. 11 to sound-absorbing material 8j shown in FIG. 18 have shapes such as concaves and convexes formed in mold 25. In the second step S2, mold 25 forms the respective concaves and convexes of polyurethane molding material 21, etc.

[0080] <Description of First Embodiment of Polyurethane Molded Body Manufacturing Method> Next, the polyurethane molded body manufacturing method will be described for each embodiment. As already explained, the optional preliminary step S0 is common to all embodiments except the third embodiment, and therefore its explanation will be omitted. Note that the first step S1 will be described regarding the type of adhesive 22 used. The first embodiment of the polyurethane molded body manufacturing method will be described with reference to Figures 19 and 20. The first to third embodiments are methods for manufacturing a polyurethane molded body 1 and a sound-absorbing material 8, and the fourth embodiment is a method for manufacturing a polyurethane molded body 20 and a sound-absorbing material 8c.

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

[0082] Next, the second step S2 will be described 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., introduced into the molds 24, 25 is compression molded using the molds 24, 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 used in compression molding in step P5 is 0.1 MPa or higher. The pressurization time is between 3 and 30 minutes.

[0083] In step P5, adjacent pieces 2 of the polyurethane molded body 1 are bonded to each other to form bonded portions 3, and communication holes 4 are formed that connect the pieces 2 to the bonded portions 3. In addition, at least a portion of the pieces 2 is bent, and at least a portion of the pieces 2 is separated from the adjacent pieces 2.

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

[0085] <Description of Second Embodiment of Polyurethane Molded Body Production Method> Next, a second embodiment of the polyurethane molded body production method will be described. The description will be made with reference to FIGS. 21 and 22 . The type of adhesive 22 used in step P3 in the first step S1 will be described. A heat-curing adhesive or a hot-melt adhesive can be used as the adhesive 22. In the first embodiment of the polyurethane molded body production method, in step P5 in the second step S2, the polyurethane molding material 21 and the like are compressed while introducing heated steam 28. In contrast, as shown in FIGS. 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 and the like are compressed at a high temperature.

[0086] In the high-temperature compression method, steam 28 is not introduced in the second step S2, so there is not enough moisture in the molding dies 24, 25 and moisture-curing adhesives cannot be used in step P3. However, compared to the molding method in which heated steam 28 is introduced, as in the first embodiment of the polyurethane molding manufacturing method, this method allows moldings to be manufactured with simpler equipment. Compression molding in step P5 involves compression at temperatures between 120°C and 160°C for 5 to 30 minutes. The pressure during compression is between 0.1 MPa and 0.5 MPa.

[0087] <Description of Third Embodiment of Polyurethane Molded Body Manufacturing Method> Next, a third embodiment of a polyurethane molded body manufacturing method will be described with reference to Figures 23 and 24. The type of adhesive 22 used in step P3 in the first step S1 will be described. The adhesive 22 can be a moisture-curing adhesive, a heat-curing adhesive, or a hot-melt adhesive. In particular, it is preferable to use a moisture-curing adhesive. This is because introducing water 42 and heating it in step P5 in the second step S2, which will be described later, fills the inside of the molding dies 24, 25 with water vapor, and the water vapor causes curing to proceed quickly.

[0088] The second step S2 includes a step P5 in which the polyurethane molding material 21 mixed with the adhesive 22 is poured into the molds 24, 25, and water 42 is poured into the mold 24, followed by heating and pressure 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 two and ten times the amount of adhesive 22. The compression molding in step P5 involves heating and compression at temperatures between 120°C and 160°C for between three and twenty minutes. The pressure during compression is between 0.1 MPa and 0.5 MPa.

[0089] <Description of Fourth Embodiment of Polyurethane Molded Body Manufacturing Method> Next, a fourth embodiment of the polyurethane molded body manufacturing method will be described with reference to FIGS. 25 and 26 . The adhesive 22 used in step P3 of the first step S1 will be described. A heat-curing adhesive or a hot-melt adhesive can be used as the adhesive 22. In step P4 of the first step S1, a substrate 40 is further placed in the molds 24 and 25. The second step S2 includes step P5, in which the polyurethane molding material 21 and the substrate 40 are compressed and molded together by heating and pressurizing. The compression molding in step P5 is performed at a temperature between 120°C and 160°C for 5 to 30 minutes. The pressure during compression is between 0.1 MPa and 0.5 MPa. When a wood-based material is used for the substrate 40, a high-temperature compression molding method with a low moisture content in the molds 24 and 25 is preferred to suppress swelling of the substrate 40.

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

[0091] For example, when molding the polyurethane molded body 20a shown in Fig. 6, in step P4, the substrate 40 is first placed in the mold 24. Next, the polyurethane molding material 21 and the like are poured onto the substrate 40, and the substrate 40 is further placed above the polyurethane molding material 21 and the like. After step P4, step P5 is performed.

[0092] <Effects of the Polyurethane Molded Body Manufacturing Method> The polyurethane molded body manufacturing method described above provides the following effects. The polyurethane molded body 1, etc., can be made primarily from waste or scrap materials, thereby enabling material recycling. This reduces the environmental impact. Even if the manufacturing method does not include the preliminary step S0, the environmental impact can be reduced by using materials processed from waste or scrap materials. The main steps in manufacturing the polyurethane molded body 1, etc., are mixing the polyurethane molding material 21 and the adhesive 22 and heat compression. Therefore, the polyurethane molded body manufacturing method can achieve recycling through a process with a low environmental impact. Furthermore, since the polyurethane molded body manufacturing method uses, for example, a polyurethane molding material 21 processed from rigid polyurethane foam for compression molding, the thickness and shape can be tailored to the application.

[0093] In the method for producing a polyurethane molded product, for example, the outer shells 11 of cells 10 of a rigid polyurethane foam are fragmented to form fragments 2, adjacent fragments 2 are bonded to each other to form joints 3, and communication holes 4 are formed between the fragments 2 and the joints 3. At least a portion of the fragments 2 is bent, and at least a portion of the fragments 2 has an end 5 that is separated from adjacent fragments 2. Thus, a polyurethane molded product 1 having a great sound absorbing effect can be produced.

[0094] Alternatively, the polyurethane molding may be produced by crushing rigid polyurethane foam and passing it through a sieve with 2 mm openings. In this case, the outer shells 11 forming the cells 10 can be more uniformly fragmented to form the fragments 2. This allows the polyurethane molding 1a to be produced with a more uniformly enhanced sound-absorbing effect.

[0095] Furthermore, according to the third embodiment of the polyurethane molded body manufacturing method, second step S2 includes 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 interior of the molded product, thereby shortening the compression molding time. For example, adding water 42 can shorten the compression molding time to about one-half to two-thirds of the time required without adding water 42. Furthermore, the polyurethane molded body 1, etc., has stronger bonding strength between the fragments 2, resulting in increased strength.

[0096] Furthermore, according to the fourth embodiment of the polyurethane molded body manufacturing method, in step P4 of the first step S1, a substrate 40 is further placed in the mold 24. Thus, the polyurethane molded body 20 can be integrally molded by bonding the polyurethane molded layer 9 and the substrate 40. The polyurethane molded body 20 and sound-absorbing material 8c described with reference to Figures 6 to 10 and 12 can be manufactured. Therefore, the step of adhering the polyurethane molded body 20 and sound-absorbing material 8c to the substrate 40 using an adhesive or the like after molding can be omitted.

[0097] <Examples of polyurethane molded body 1 according to the first aspect> Next, examples of the present invention will be described. First, examples of the polyurethane molded body 1 according to the first aspect will be described. Examples of the polyurethane molded body 1 according to the first aspect of the present invention are Example 1 and Example 2, and Comparative Examples 1 to 3 are also shown for comparison. Example 1 is a sound-absorbing material 8a made from the polyurethane molded body 1a of the present invention, and Example 2 is a sound-absorbing material 8b made from the polyurethane molded body 1b. Comparative Example 1 is a rigid polyurethane foam before pulverization. Comparative Example 2 is rock wool, and Comparative Example 3 is glass wool. Note that the polyurethane molded body 1a of Example 1 corresponds to Figures 1 and 2, the polyurethane molded body 1b of Example 2 corresponds to Figures 3 and 4, and Comparative Example 1 corresponds to Figure 5. Note that the sound-absorbing materials 8a and 8b used in the measurements here both have smooth surfaces.

[0098] Examples 1 and 2 were molded using the molded article manufacturing method described in the first embodiment of the polyurethane molded article manufacturing method. In these examples, a polymeric adhesive having a structure derived from methylene diisocyanate was used, and the adhesive was a moisture-curing adhesive having an isocyanate group at the end. The molding conditions were compression molding at a pressure of 0.2 Pa for 5 minutes. The size of the molded product was 200 mm x 200 mm x 30 mm.

[0099] 27, the size of the polyurethane molding material 21 in Example 1 was previously passed through a sieve with 2 mm openings, while that in Example 2 was previously not passed through a sieve with 2 mm openings. In Example 2, the size of one side of the polyurethane molding material 21 was approximately 50 mm or less. The densities of Example 1, Example 2, and Comparative Example 1 were the highest in Example 1, which had the smallest size of the polyurethane molding material 21, and the lowest in the Comparative Example.

[0100] Next, when comparing the breathability, as shown in FIG. 27, Example 1 and Example 2 had a breathability of 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. As a result, Examples 1 and 2 have higher breathability than Comparative Example 1. The method for measuring breathability has already been described.

[0101] Next, comparing the thermal conductivities, as shown in Figure 27, Example 1 had a thermal conductivity of 0.0334 w / m.K, Example 2 had a thermal conductivity of 0.0330 w / m.K, and Comparative Example 1 had a thermal conductivity of 0.0375 w / m.K. Although the difference between Example 1 and Example 2 is small, a comparison of Comparative Example 1 with Examples 1 and 2 reveals a difference that is reproducible. In other words, the polyurethane molded product 1 of the present invention has a lower thermal conductivity than the rigid polyurethane foam before pulverization, and therefore has high heat insulating performance.

[0102] Next, normal incidence sound absorption coefficients are compared with reference to Fig. 28. Measurement of normal incidence sound absorption coefficient was performed in accordance with JIS A 1405-1:2007 "Measurement of sound absorption coefficient and impedance by acoustic tube - Part 1: Standing wave ratio method". In Fig. 28, A indicates Example 1, B indicates Example 2, and C indicates Comparative Example 1. Over 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] 28, the frequency ranges in which the normal incidence sound absorption coefficients of Examples 1 and 2 exhibit characteristic values ​​will be described. The sound-absorbing material 8a using the polyurethane molding 1a exhibits a particularly high normal incidence sound absorption coefficient in the frequency range between 500 Hz and 800 Hz, exhibiting a value exceeding 80%. The sound-absorbing material 8b using the polyurethane molding 1b exhibits a particularly high normal incidence sound absorption coefficient in the frequency range around 1000 Hz, exhibiting a value exceeding 90%.

[0104] 28, both Example 1 and Example 2 have significantly higher normal incidence sound absorption coefficients, at 65% or more, in the frequency range from 2000 Hz to 6500 Hz than Comparative Example 1. Therefore, although Example 1 and Example 2 differ in the frequency ranges in which their normal incidence sound absorption coefficients are significantly higher, both have a large sound absorbing effect.

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

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

[0107] As explained above, when rigid polyurethane, which is made of the same material, is pulverized or finely divided into a certain range, it has a higher normal incident sound absorption coefficient and a greater sound absorbing effect than rigid polyurethane foam. Furthermore, rigid polyurethane pulverized into a certain range has a higher normal incident sound absorption coefficient in the frequency range of 100 Hz to 1000 Hz compared to rock wool or glass wool, which are different materials. Therefore, the polyurethane molded body 1 molded by the polyurethane molded body manufacturing method of the present invention and the sound-absorbing material 8 made of the polyurethane molded body 1 have a greater sound absorbing effect and a greater heat insulating effect.

[0108] <Example of Sound-Absorbing Material 8 According to the Second Aspect> Next, an example of the sound-absorbing material 8 according to the second aspect of the present invention will be described. Example 3 is an example of the sound-absorbing material 8 according to the second aspect of the present invention. The comparative example here is Comparative Example 4, which is Example 1 of the polyurethane molded body 1 according to the first aspect of the present invention. That is, it is a sound-absorbing material 8a made of a polyurethane molded body 1a. As shown in FIG. 11 , which has already been described, Example 3 has a convex portion 34 on the first surface 31a of the sound-absorbing material 8c. The convex portion 34 is a conical convex portion 34a, with a base diameter of 10 mm and a convex portion height h of 10 mm. The thickness L of the sound-absorbing material 8c excluding the convex portion 34 is 20 mm. The center-to-center distance between adjacent conical convex portions 34a is 15 mm. Comparative Example 4 is a plate material with a thickness L of 30 mm. The crushed size and density of Example 3 are the same as those of Example 1 shown in FIG. 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 Comparative Example 4. This is particularly suitable for use in ordinary homes. Therefore, compared to Comparative Example 4, which does not have the recesses 33, 35, or protrusions 34, Example 3 has an even higher normal incidence sound absorption coefficient, and therefore provides a greater sound absorption effect.

[0110] REFERENCE SIGNS LIST 1, 1a, 1b, 20, 20a, 20b, 20c, 20d, 20e Polyurethane molded body 2 Fragment 3 Joint 4 Communication hole 5 End 8, 8a, 8b, 8c, 8d, 8e, 8f, 8g, 8h, 8j Sound absorbing material 26 Hole 31 Surface 33, 35 Concave portion 34 Convex portion

Claims

1. A polyurethane molded body, a polyurethane piece, and a plurality of adjacent said pieces having a joint portion where they are joined to each other, provided with communication holes, said piece is in a state where at least a part is refracted, A polyurethane molded body formed in a state where at least a part has an end portion separated from the adjacent piece.

2. The polyurethane molded body according to claim 1, wherein the piece has passed through a sieve with a mesh size of 2 mm in advance.

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

4. A sound-absorbing material comprising the 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 body has a normal incidence sound absorption rate 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 body has a normal incidence sound absorption rate 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 body has a normal incidence sound absorption rate of 60% or more in the frequency range from 2000 Hz to 6500 Hz.

8. The sound-absorbing material according to claim 4, wherein the polyurethane molded body has a surface having recesses and / or protrusions.

9. The sound-absorbing material according to claim 8, having a normal incidence sound absorption rate of 65% or more in the frequency range from 1000 Hz to 2500 Hz.

10. The polyurethane molded body according to any one of claims 1 to 3, wherein the fragment has a portion with holes opened at least partially, and regions adjacent to each other across the fragment are formed in a communicating state.

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

12. The polyurethane molded body according to any one of claims 1 to 3, wherein the air permeability is 4.68 cm3 / cm2·s or more and 6.93 cm3 / cm2·s or less.

13. The polyurethane molded body is plate-shaped and includes a first surface and a second surface facing each other, and at least one of the first surface and the second surface has recesses and / or protrusions. The sound-absorbing material according to claim 4.

14. The sound-absorbing material according to claim 8, wherein the recesses and / or the protrusions are formed in a conical shape or a polygonal pyramid shape.

15. The sound-absorbing material according to claim 13, wherein the recesses and / or the protrusions are formed in a conical shape or a polygonal pyramid shape.

16. The sound-absorbing material according to claim 8, wherein the protrusions are in a shape extending in one direction.

17. The sound-absorbing material according to claim 13, wherein the protrusions are in a shape extending in one direction.

18. The sound-absorbing material according to claim 8, wherein the protrusions are in a lattice shape.

19. The sound-absorbing material according to claim 13, wherein the protrusions are in a lattice shape.

20. The protrusions are plate-shaped protrusions, and the plate-shaped protrusions are formed in sets of several pieces with the recesses therebetween, and the extending directions of the plate-shaped protrusions are different by 90 degrees between adjacent sets. The sound-absorbing material according to claim 8.

21. The protrusions are plate-shaped protrusions, and the plate-shaped protrusions are formed in sets of several pieces with the recesses therebetween, and the extending directions of the plate-shaped protrusions are different by 90 degrees between adjacent sets. The sound-absorbing material according to claim 13.

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

23. A molded article comprising the polyurethane molded article according to claim 1 and a substrate.

24. A method for producing a polyurethane molded article according to claim 1, comprising: a first step of pulverizing a polyurethane foam to form a pulverized product; a second step of mixing the pulverized product and an adhesive and charging the mixture into a mold; and a third step of compression molding the pulverized product.

25. The method for producing a polyurethane molded article according to claim 24, wherein water is charged into the mold in the third step.

26. The method for producing a polyurethane molded article according to claim 24 or 25, wherein a substrate is further charged into the mold in the second step.