JP2024052964A - Soundproofing materials - Google Patents

Abstract

[Problem] To provide a soundproofing material capable of improving soundproofing performance and a manufacturing method thereof. [Solution] The soundproofing material 10 includes a polyurethane foam 11 for absorbing sound. This soundproofing material 10 is manufactured by integrating a breathable skin material with the surface of the polyurethane foam, and by performing a blowing process in which compressed gas is blown from the surface of the foam-molded polyurethane foam 11 into the interior through the skin material, thereby additionally machining rupture holes 32Y in the cell membrane 31 of a plurality of foam cells 30 contained in the polyurethane foam 11. [Selected Figure] Figure 17

Description

This disclosure relates to a foam-containing soundproofing material and a method for producing the same.

Patent document 1 describes a soundproofing material that contains polyurethane foam with open cells.

Jitsuzen No. 49-081516 (specification, page 2)

There is a demand for improved soundproofing performance compared to the conventional soundproofing materials mentioned above.

The first aspect of the invention made to solve the above problem is a method for manufacturing a soundproofing material containing polyurethane foam, which comprises integrating the polyurethane foam with a pair of breathable skin materials so that the polyurethane foam is sandwiched between the pair of skin materials, and performing a blowing process in which compressed gas is blown into the foam-molded polyurethane foam through the skin materials to add rupture holes in the cell membrane of multiple foam cells contained in the polyurethane foam.

The second aspect of the invention is the method for producing the soundproofing material described in the first aspect, in which the blowing process is performed by bringing the tip face of the nozzle that ejects the compressed gas into contact with or close to the surface of the skin material.

The third aspect of the invention is the method for producing the soundproofing material described in the second aspect, in which the dynamic pressure of the compressed gas is 0.1 to 1 MPa.

The fourth aspect of the invention is a method for producing a soundproofing material according to any one of the first to third aspects, in which a piercing process is performed in which the tips of a plurality of needles or blades are pierced through the skin material into the surface of the polyurethane foam before the blowing process.

The fifth aspect of the invention is a soundproofing material containing polyurethane foam, in which the polyurethane foam and a pair of breathable skin materials are integrated together so that the polyurethane foam is sandwiched between the pair of skin materials, and the polyurethane foam has rupture holes formed in the cell membranes of a plurality of foam cells, and the number of closed cells among the foam cells is smaller toward the surface to which the skin materials are integrated than toward the inside of the polyurethane foam.

The sixth aspect of the invention is a soundproofing material containing polyurethane foam, in which the polyurethane foam and a pair of breathable skin materials are integrated together so that the polyurethane foam is sandwiched between the pair of breathable skin materials, and the polyurethane foam has rupture holes formed in the cell membrane of a plurality of foam cells contained therein, and the amount of air permeability of the polyurethane foam is greater closer to the surface to which the skin materials are integrated than to the interior of the polyurethane foam.

The seventh aspect of the invention is the soundproofing material according to the fifth or sixth aspect, in which the polyurethane foam has a flat shape, the skin material is integrated on both sides of the polyurethane foam, and the ratio of the number of closed cells per unit cross-sectional area in the central part in the thickness direction of the polyurethane foam to the number of closed cells per unit cross-sectional area in the surface layer part up to a depth of 3 mm from both sides of the polyurethane foam is 0.7 or less.

The eighth aspect of the invention is the soundproofing material according to any one of the fifth to seventh aspects, in which the ratio of the number of open cells to the total number of foamed cells is greater closer to the surface where the skin material is integrated than to the interior of the polyurethane foam.

The ninth aspect of the invention is the soundproofing material according to any one of the fifth to eighth aspects, in which the rupture holes are formed by rupturing the cell membrane due to the wind pressure of compressed gas blown into the polyurethane foam through the skin material.

The tenth aspect of the invention is the soundproofing material according to any one of the fifth to ninth aspects, in which the 50% compression hardness of the polyurethane foam based on the E method of JIS K6400-2:2012 is 500N to 3000N.

In the first aspect of the invention, the polyurethane foam is integrated with a pair of breathable skin materials so that the polyurethane foam is sandwiched between them. A blowing process is then performed through the skin materials to blow compressed gas into the polyurethane foam, and rupture holes are added to the cell membrane of the multiple foam cells. This makes it easier for the foam cells on the surface side of the polyurethane foam where the skin materials are integrated to communicate with each other, making it easier for sound (air) to penetrate into the interior of the polyurethane foam. This makes it possible to improve the sound absorption performance of the polyurethane foam while protecting it with the skin materials, and to improve the soundproofing performance of the soundproofing material.

In the second aspect of the invention, the blowing process is performed by bringing the tip face of the nozzle that ejects the compressed gas into contact with or close to the surface of the skin material. This makes it easier to blow compressed gas into the polyurethane foam and reduces variation in the amount of compressed gas blown in. In this case, by setting the dynamic pressure of the compressed gas to 0.1 to 1 MPa (third aspect of the invention), it becomes easier to form rupture holes that reach the inside of the polyurethane foam.

In the fourth aspect of the invention, the tip of a needle or blade is pierced through the skin material into the surface of the polyurethane foam before the blowing process, making it easier to blow compressed gas into the interior of the polyurethane foam through the puncture.

In the soundproofing material of the fifth aspect of the invention, the polyurethane foam and a pair of skin materials are integrated so that the polyurethane foam is sandwiched between the pair of breathable skin materials. In addition, foaming holes are formed in the cell membrane during foaming of the polyurethane foam, and the number of closed cells among the foam cells is smaller closer to the surface where the skin materials are integrated than to the inside of the polyurethane foam. This makes it possible to increase the number of open cells that are connected by rupture holes or the like closer to the surface than to the inside of the polyurethane foam. In addition, in the soundproofing material of the sixth aspect of the invention, the air permeability of the polyurethane foam is larger closer to the surface where the skin materials are integrated than to the inside of the polyurethane foam. With these configurations, it is possible to increase the breathability of the surface side of the polyurethane foam, and it is possible to increase the sound absorption performance of the polyurethane foam from the surface side, and as a result, it is possible to improve the soundproofing performance of the soundproofing material.

In the seventh aspect of the invention, the polyurethane foam has a flat shape and has skin materials integrated on both sides thereof, and the ratio of the number of closed cells per unit cross-sectional area in the central part of the polyurethane foam in the thickness direction to the number of closed cells per unit cross-sectional area in the surface layer parts up to a depth of 3 mm from both sides of the polyurethane foam is 0.7 or less. This configuration makes it possible to particularly improve the sound absorption performance of the polyurethane foam.

In the eighth aspect of the invention, the ratio of the number of open cells to the total number of foam cells is greater closer to the surface where the skin material is integrated than to the interior of the polyurethane foam. This configuration improves the breathability of the surface side of the polyurethane foam, making it easier for air to reach the interior of the polyurethane foam, and further improves the sound absorption performance of the polyurethane foam.

As in the ninth aspect of the invention, the rupture holes in the polyurethane foam can be easily formed by rupturing the cell membrane with the wind pressure of compressed gas blown into the polyurethane foam through the skin material.

In the tenth aspect of the invention, the 50% compression hardness of the polyurethane foam is 500 to 3000 N, so that rigidity can be ensured. This makes it possible to stabilize the shape of the polyurethane foam. In polyurethane foam with a 50% compression hardness in the above range, for example, if a break hole is formed in the cell membrane by roll crushing, the foam will be crushed and not restored, resulting in low dimensional accuracy and wrinkles that can lead to a poor appearance. However, the configuration of the present invention eliminates the need for roll crushing, making it possible to prevent the polyurethane foam from losing dimensional accuracy or worsening in appearance.

FIG. 1 is a cross-sectional side view of a soundproofing material according to a first embodiment. Enlarged cross-sectional side view of polyurethane foam soundproofing material Enlarged cross-sectional side view of polyurethane foam cells Side cross-sectional view of soundproofing material undergoing blow treatment Side cross-sectional view showing an example of soundproofing material use 10 is a cross-sectional side view of a soundproofing material according to a second embodiment. Enlarged cross-sectional side view of polyurethane foam soundproofing material Enlarged cross-sectional side view of polyurethane foam cells (A) is a side cross-sectional view of a mold in an open state and a skin material fixed to the mold, and (B) is a side cross-sectional view of the mold and the skin material when the raw material is injected in the open state. (A) A side cross-sectional view of the mold and the skin when the mold is closed and the raw material starts to foam, (B) A side cross-sectional view of the polyurethane foam and the skin that have been foamed in the mold. Side cross-sectional view of soundproofing material with polyurethane foam surface being blown A cross-sectional side view of a soundproofing material being blown from the skin side. Side cross-sectional view showing an example of soundproofing material use 11 is a cross-sectional side view of a soundproofing material according to a third embodiment. (A) is a side cross-sectional view of a mold in an open state and a skin material fixed to the mold, and (B) is a side cross-sectional view of the mold and the skin material when the raw material is injected in the open state. (A) A side cross-sectional view of the mold and the skin when the mold is closed and the raw material starts to foam, (B) A side cross-sectional view of the polyurethane foam and the skin that have been foamed in the mold. A cross-sectional side view of a soundproofing material being blown from the skin side. Side cross-sectional view showing an example of soundproofing material use FIG. 13 is a perspective view of a soundproofing material according to a fourth embodiment. FIG. 5 is a side cross-sectional view of a soundproofing material according to a fifth embodiment; Side cross-sectional view of polyurethane foam being pierced from the exposed side A cross-sectional side view of a polyurethane foam being pierced from the skin side. Enlarged image of foam cells on the outer surface of polyurethane foam Table showing examples and comparative examples

[First embodiment]
As shown in Fig. 1, the soundproofing material 10 according to the first embodiment is made of polyurethane foam 11. In this embodiment, the polyurethane foam 11 has a flat shape, has open cells, and has sound absorbing properties. The flat shape includes a plate shape and other flat shapes, and also includes shapes with irregularities formed on the front or back surface. In this embodiment, the polyurethane foam 11 has a flat plate shape.

The polyurethane foam 11 is preferably a semi-rigid polyurethane foam. Flexible polyurethane foam is soft and has low rigidity, while rigid polyurethane foam is hard and too rigid, so a semi-rigid polyurethane foam with appropriate rigidity is more preferable. For example, a semi-rigid polyurethane foam having a 50% compression hardness of 500 to 3000 N based on the E method of JIS K6400-2:2012 is preferable.

The apparent density of the polyurethane foam 11 (based on JIS K7222:2005) is preferably 30 to 90 kg/ ^m3 . An apparent density of 40 kg/ ^m3 or more particularly improves the sound insulation of the polyurethane foam 11, and an apparent density of 60 kg/m3 or ^less is particularly preferred in terms of reducing the weight of the polyurethane foam 11. The thickness of the polyurethane foam 11 is, for example, 1 to 50 mm.

As shown in FIG. 3, the polyurethane foam 11 has densely packed foam cells 30. The foam cells 30 include open cells 30A and closed cells 30B. The open cells 30A communicate with each other through cell holes 32 that penetrate the cell membrane 31 that separates the foam cells 30. The closed cells 30B are surrounded by cell membranes 31 that do not have cell holes 32, and do not communicate with other foam cells 30. Here, in the present disclosure, the presence or absence of cell holes 32 is determined in an image of the polyurethane foam 11 magnified 35 times with a microscope (e.g., SEM, etc.), and if the cell holes 32 are not visible in the cell membrane 31 surrounding the foam cells 30, the foam cells 30 are considered to be closed cells 30B. For example, the polyurethane foam 11 contains 20 to 150 foam cells 30 per 25 mm.

1 and 2, the polyurethane foam 11 has a sound absorbing structure 40 including a sound absorbing surface 11M that allows sound (air) to enter the polyurethane foam 11 and a sound absorbing path 33 that connects from the sound absorbing surface 11M to the inside of the polyurethane foam 11. In detail, as shown in FIG. 3, the sound absorbing surface 11M is a surface of the polyurethane foam 11 where the open cells 30A of the foam cells 30 are open. The sound absorbing path 33 is composed of a plurality of open cells 30A that connect from the sound absorbing surface 11M to the inside of the polyurethane foam 11. The sound absorbing surface 11M of the polyurethane foam 11 may not have a skin layer, or may have a breathable skin layer. Here, in the present disclosure, the skin layer refers to a surface layer that has a higher apparent density than the inner part of the polyurethane foam 11, for example, a part from the surface of the polyurethane foam 11 to a depth of 0.5 to 1 mm. For example, in FIG. 23, the surface of the polyurethane foam 11 is shown on the top, and the skin layer is indicated by the reference number 16.

Here, the above-mentioned cell holes 32 include foam holes 32X formed during foam molding of the polyurethane foam 11, and rupture holes 32Y formed by rupturing the cell membrane 31 after foam molding. Specifically, as described below, the rupture holes 32Y are formed when the cell membrane 31 is ruptured by the wind pressure of compressed gas blown into the polyurethane foam 11 from the surface (sound absorbing surface 11M). For example, the ruptured cell membrane 31 may be attached to the opening edge of the rupture hole 32Y.

In this embodiment, the sound absorbing structure 40 of the polyurethane foam 11 is structured such that the total opening area of the cell holes 32, including the foaming holes 32X and the rupture holes Y, is larger closer to the sound absorbing surface 11M than to the inside of the polyurethane foam. Also, in the sound absorbing structure 40, the air permeability of the polyurethane foam 11 is larger closer to the sound absorbing surface 11M than to the inside of the polyurethane foam 11. According to these configurations, the air permeability of the part of the polyurethane foam 11 on the sound absorbing surface 11M side is increased, and it is possible to improve the sound absorbing performance of the polyurethane foam 11 (i.e., the soundproofing material 10) against sound from the sound absorbing surface 11M side. Also, since the air permeability of the inside of the polyurethane foam 11 is lower than that of the part on the sound absorbing surface 11M side, it is also possible to improve the sound insulation of the polyurethane foam 11. The above-mentioned comparison of the total opening area can be performed, for example, by calculating the area of the cell holes 32 in an enlarged image of a predetermined region of the cut surface of the polyurethane foam 11 (for example, the surface side region S and the central region D shown in FIG. 2) using area calculation software, and comparing them at different depths from the sound absorbing surface 11M. In detail, since the direction in which the cell holes 32 are opened is random and isotropic as a whole, it is sufficient to measure the planar total area of the cell holes 32 in a predetermined region of the cut surface in any direction and compare them at different depths. In addition, the air permeability of the polyurethane foam 11 can be compared, for example, by dividing the polyurethane foam 11 into three equal parts in the thickness direction and measuring the air permeability (based on JIS K6400-7 B method: 2012) between the central part in the thickness direction and the part on the sound absorbing surface 11M side.

In addition, in the sound absorbing structure 40 of the polyurethane foam 11, the number of closed cells 30B is smaller closer to the sound absorbing surface 11M than to the inside of the polyurethane foam 11. Specifically, the closed cell ratio, which is the ratio of the number of closed cells 30B per unit cross-sectional area in the surface layer 10S from the sound absorbing surface 11M to a depth of 3 mm to the number of closed cells 30B per unit cross-sectional area in the central part of the polyurethane foam 11 in the thickness direction, is preferably 0.7 or less. Here, the central part of the polyurethane foam 11 in the thickness direction is a region (e.g., the central region D shown in FIG. 2) that is located inside the surface layer 10S and includes the central position 10D in the thickness direction of the polyurethane foam 11 (in the example of this embodiment, the position at a depth of 10 mm from the sound absorbing surface 11M). A configuration with a closed cell ratio of 0.7 or less makes it possible to particularly improve the sound absorbing performance of the polyurethane foam 11. This closed cell ratio is more preferably 0.65 or less, and even more preferably 0.6 or less. In the present embodiment, the ratio of the number of open cells 30A to the total number of foam cells 30 in the sound absorbing structure 40 is higher closer to the sound absorbing surface 11M than to the inside of the polyurethane foam 11. This configuration also improves the breathability of the polyurethane foam 11 on the sound absorbing surface 11M side, making it easier to ventilate the polyurethane foam 11, and further improves the sound absorbing performance of the polyurethane foam. The number of closed cells 30B and open cells 30A can be obtained, for example, by counting the number of closed cells 30B and open cells 30A in an enlarged image (e.g., SEM image, etc.) of a surface side region S of a predetermined area included in the surface layer portion 10S of the cut surface of the polyurethane foam 11 and a central region D of a predetermined area including the central position 10D (see FIG. 2). Then, by comparing the numbers between the above-mentioned regions of the polyurethane foam 11 at different depths from the sound absorbing surface 11M, the closed cell ratio, etc. can be obtained.

In addition, in the polyurethane foam 11 of the soundproofing material 10, the ratio of the major axis to the minor axis of the cell shape of the foam cells 30 in the central part in the thickness direction (central region D) is preferably 1 to 1.5. The major axis is the length of the longest part of the foam cells 30, and the minor axis is the length of the smallest part of the foam cells 30. The directions of the major axis and the minor axis differ for each foam cell 30, but generally, the major axis direction is approximately perpendicular to the thickness direction, and the minor axis direction is approximately the same as the thickness direction. This major axis/minor axis ratio can be calculated, for example, from the ratio of the average major axis and the average minor axis of the five foam cells, including the largest foam cell 30, the smallest foam cell 30, and any other three foam cells 30, among the foam cells 30 shown in the enlarged image of the central region D (see FIG. 2).

In this embodiment, both the front and back sides of the polyurethane foam 11 are sound absorbing surfaces 11M, and the above-mentioned sound absorbing structure 40 is provided on both the front and back sides. The sound absorbing surface 11M may be disposed on the entire outer surface of the polyurethane foam 11, or may be disposed on only one side of the front or back.

In this embodiment, the outer peripheral surface 11E of the polyurethane foam 11 is a cut surface where no skin layer is formed. In addition, in the outer peripheral surface 11E, the part of the cell membrane 31 where the cell holes 32 are not open reflects light and is easy to shine. That is, the more closed cells 30B there are, the more the part is easy to shine. On the other hand, the part of the cell membrane 31 where the total opening area of the cell holes 32 is large is difficult to shine. Therefore, when looking at the outer peripheral surface 11E of the polyurethane foam 11 of this embodiment, the closer it is to the sound absorbing surface 11M on the front and back sides from the center in the thickness direction, the more difficult it is to shine. In this embodiment, the surface layer portion 10S constituting the sound absorbing surface 11M on the front and back sides is a layered region that is difficult to shine compared to the deeper part, and the break holes 32Y are unevenly distributed in this layered region.

The soundproofing material 10 is manufactured, for example, as follows. To manufacture the soundproofing material 10, first, polyurethane foam 11 is obtained by foam molding in a mold (i.e., by molding). The polyurethane foam 11 may also be formed by slab molding.

When foam molding the polyurethane foam 11, it is preferable to use, for example, a straight-chain hydrocarbon wax as a release agent. This makes it easy to form an open cell surface 11MA (i.e., a breathable surface) on the surface of the polyurethane foam 11, where the foam cells 30, including the open cells 30A, are open. Specifically, the straight-chain hydrocarbon wax is applied to the molding surface of the foam molding mold that forms the open cell surface 11MA, and then the polyurethane raw material is injected into the mold and foamed and cured to form the polyurethane foam 11.

The above-mentioned linear hydrocarbon waxes include, for example, paraffin wax, Fischer-Tropsch wax, and Sasol wax. Solvent-based release agents dispersed in an organic solvent, and water-based release agents dispersed in water using an emulsifier can be used. In addition, branched hydrocarbon waxes include, for example, microcrystalline wax and modified polyethylene wax. Solvent-based release agents and water-based release agents can be used.

After molding, the polyurethane foam 11 is cut appropriately and then subjected to a blowing process as shown in FIG. 4. In the blowing process, compressed gas is blown into the polyurethane foam 11 to break the cell membrane 31 of the foam cells 30 of the polyurethane foam 11, forming a break hole 32Y.

Specifically, in the blowing process, compressed gas (e.g., air) is blown into the open cell surface 11MA on the front and back sides of the polyurethane foam 11. In detail, as shown in FIG. 4, the blowing process is performed by bringing the tip surface of the nozzle N of the blow gun that ejects the compressed gas (i.e., the opening edge of the nozzle) into contact with the open cell surface 11MA of the polyurethane foam 11. The blowing process may also be performed by bringing the nozzle N close to the open cell surface 11MA (e.g., by separating it by a distance of 2 mm or less). These methods make it easier to blow the compressed gas into the polyurethane foam 11, and also make it possible to suppress the variation in the amount of compressed gas blown in. In addition, in this case, it is preferable to set the dynamic pressure of the compressed gas blown into the polyurethane foam 11 to 0.1 to 1.0 MPa. This makes it easier to form a sound absorbing path to the inside of the polyurethane foam 11. The compressed gas used in the blowing process may be an inert gas such as nitrogen or argon, in addition to air.

When the blowing process is performed, the total opening area of the foaming holes 32X formed during foaming increases, particularly in the portion of the polyurethane foam 11 near the open cell surface 11MA, and rupture holes 32Y are formed in the polyurethane foam 11, adding sound absorption paths 33. This forms the sound absorbing structure 40. At this time, the sound absorbing surface 11M is formed from the open cell surface 11MA.

In this embodiment, the blowing process is performed over the entire front and back surfaces of the polyurethane foam 11, but it may be performed only on a portion of the surface. For example, it may be performed over the entire front or back surface of the polyurethane foam 11, or it may be performed over only a portion of at least one of the front and back surfaces. For example, if the nozzle N of the blow gun used in the blowing process is shaped like a T, the nozzle N can be made wider to eject compressed gas, thereby making the blowing process more efficient. The blowing process may be performed while feeding the polyurethane foam 11. In this case, it is preferable to perform the blowing process with the nozzle N close to the polyurethane foam 11 without abutting it. In this case, the blowing process can be performed more efficiently by using a T-shaped nozzle N that is wider than the polyurethane foam 11.

Before the blowing process, a piercing process may be performed in which the tips of multiple needles or blades are pierced into the open cell surface 11MA of the polyurethane foam 11. This makes it easier to blow compressed gas into the interior of the polyurethane foam 11 through the perforations formed by the piercing process. In addition, before the blowing process, a cutting process may be performed in which cuts are made in the sound absorbing surface 11M with a cutter. This process also makes it easier to blow compressed gas into the interior of the polyurethane foam 11 through the cuts. These piercing and cutting processes are particularly effective when blowing is performed on the surface of the polyurethane foam 11 on which the skin layer is formed. In this case, the perforations or cuts are formed to a depth that does not penetrate the polyurethane foam 11 and is deeper than the skin layer, making it easier to blow compressed gas into the interior of the polyurethane foam 11. When perforations or cuts are formed on both the front and back sides of the polyurethane foam 11, it is preferable to form the perforations or cuts at positions that do not overlap when viewed from the thickness direction. In this way, the rigidity of the polyurethane foam 11 can be suppressed from decreasing.

When the above-mentioned blowing process is completed, the soundproofing material 10 shown in FIG. 1 is completed. In this embodiment, the surface of the polyurethane foam 11 is blown to connect the foam cells 30 with each other through the rupture holes 32Y, which makes it possible to provide a sound-absorbing structure in which the amount of air permeation is greater and the total opening area of the cell holes 32 is greater the closer it is to the surface from the inside.

The details of the raw materials for polyurethane foam 11 are as follows:

The polyol component may be any of the known ether polyols, ester polyols, ether ester polyols, polymer polyols, etc., used in the production of polyurethane foams, either alone or in combination. Examples of ether polyols include polyhydric alcohols such as ethylene glycol, propylene glycol, glycerin, and trimethylolpropane, or polyether polyols obtained by adding alkylene oxides such as ethylene oxide and propylene oxide to the polyhydric alcohols. Examples of ester polyols include polyester polyols obtained by polycondensation of aliphatic carboxylic acids such as malonic acid, succinic acid, and adipic acid, or aromatic carboxylic acids such as phthalic acid, and aliphatic glycols such as ethylene glycol, diethylene glycol, and propylene glycol. In addition, ether ester polyols containing both ether groups and ester groups in the polyol, and polymer polyols obtained by polymerizing ethylenically unsaturated compounds in ether polyols may also be used.

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

The foaming agent is not particularly limited, but water is preferred. Carbon dioxide gas, pentane, hydrofluoroolefin (HFO), etc. may also be used as a foaming assistant in combination with the foaming agent water.

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

The raw material for polyurethane foam 11 may contain a foam stabilizer. Any known foam stabilizer used in the manufacture of polyurethane foam may be used, such as silicone-based foam stabilizers and non-silicone surfactants.

The raw materials for polyurethane foam 11 are prepared in two parts: Liquid A, which is a mixture of a polyol component, a blowing agent, a catalyst, etc.; and Liquid B, which contains a polyisocyanate component. If the raw materials for polyurethane foam 11 contain a foam stabilizer, these are mixed into Liquid A.

In the manufacturing method of the soundproofing material 10 of this embodiment, a blowing process is performed in which compressed gas is blown into the polyurethane foam 11 from the open cell surface 11MA to form rupture holes 32Y in the cell membrane 31 of the multiple foamed cells 30, and a sound absorbing path 33 is added that connects the sound absorbing surface 11M of the polyurethane foam 11 to the inside. This improves the sound absorbing performance of the polyurethane foam 11, and makes it possible to improve the sound absorbing performance of the soundproofing material 10.

In this embodiment, the cell membrane is broken by the wind pressure of the compressed gas during the blowing process, which makes it easy to form the break holes 32Y in the polyurethane foam 11.

In the soundproofing material 10 of this embodiment, the total opening area of the cell holes 32, including the foaming holes 32X and the rupture holes 32Y formed in the cell membrane 31 during foaming of the polyurethane foam 11, is larger the closer to the surface (sound absorbing surface 11M) than the inside of the polyurethane foam 11. Also, the air permeability of the polyurethane foam 11 is larger the closer to the sound absorbing surface 11M than the inside of the polyurethane foam 11. With these configurations, it is possible to increase the air permeability of the part of the polyurethane foam 11 on the sound absorbing surface 11M side, and it is possible to improve the sound absorbing performance of the polyurethane foam 11 against the sound absorbing surface 11M side of the polyurethane foam 11, and as a result, it is possible to improve the soundproofing performance of the soundproofing material 10. In addition, since the air permeability can be lowered inside the polyurethane foam than the part on the sound absorbing surface 11M side, it is also possible to improve the sound insulation of the polyurethane foam 11. Moreover, by making it easier for sound (air) to enter the inside of the polyurethane foam 11, it is possible to suppress the reflection of sound incident on the sound absorbing surface 11M to the outside. As a result, it is possible to improve the soundproofing performance of the soundproofing material 10.

In addition, in polyurethane foam 11, the number of closed cells 30B that do not have cell holes 32 in the cell membrane 31 is smaller closer to the sound absorbing surface 11M than to the interior of polyurethane foam 11. Therefore, it is possible to increase the number of open cells 30A that are connected by cell holes 32 among the foam cells 30, and it is possible to increase the breathability closer to the sound absorbing surface 11M than to the interior of polyurethane foam 11. This makes it possible to further improve the sound absorbing performance of polyurethane foam 11.

Furthermore, the ratio of the number of closed cells 30B per unit cross-sectional area in the central part of the polyurethane foam 11 in the thickness direction to the number of closed cells per unit cross-sectional area in the surface layer 10S from the sound absorbing surface 11M to a depth of 3 mm is 0.7 or less, which makes it possible to particularly improve the sound absorbing performance of the polyurethane foam 11.

In addition, by setting the 50% compression hardness of the polyurethane foam to 500 to 3000 N, it is possible to ensure the rigidity of the polyurethane foam 11 and to ensure the stability of the shape of the polyurethane foam 11. In polyurethane foam 11 with a 50% compression hardness in the above range, for example, when a fracture hole 32Y is formed in the cell membrane 31 by roll crushing, the polyurethane foam 11 is crushed and does not recover, which reduces the dimensional accuracy and tends to cause wrinkles and a poor appearance. However, according to this embodiment, roll crushing is not necessary, so it is possible to prevent the dimensional accuracy of the polyurethane foam 11 from decreasing and the appearance from deteriorating.

In the soundproofing material 10 of this embodiment, the sound absorbing surface 11M and the sound absorbing path 33 are arranged on both sides in the thickness direction of the flat polyurethane foam 11, thereby improving the sound absorption performance of the sound from both sides.

Figure 5 shows an example of the use of the soundproofing material 10 of this embodiment. In this example, the soundproofing material 10 is provided in a soundproofing structure of a building or vehicle. Specifically, in this soundproofing structure, the soundproofing material 10 is sandwiched between a pair of plate-shaped sound-insulating materials 71, 72 in a close contact state or spaced apart. When in a close contact state, the soundproofing material 10 may be closely contacted to the sound-insulating materials 71, 72 in a non-adhesive state. Examples of the sound-insulating materials 71, 72 include steel plates, gypsum boards, concrete, and other materials having sound-insulating properties, such as double floors, double walls, and double ceilings of buildings, and body panels of vehicles such as vehicles and sound-insulating mats that are layered thereon. In this way, according to a soundproofing structure in which the soundproofing material 10 of this embodiment is placed between a pair of sound-insulating materials 71, 72, it is possible to improve sound absorption performance and sound insulation performance.

[Second embodiment]
As shown in Fig. 6, the soundproofing material 10V according to the second embodiment has a skin material 20 integrated with a portion of the surface of the polyurethane foam 11. In the soundproofing material 10V of this embodiment, the polyurethane foam 11 has a flat shape, and the skin material 20 is integrated with only one of the front and back surfaces. Note that examples of the flat shape include a plate shape and other flat shapes, and the flat shape also includes a shape in which irregularities are formed on the front or back surface. In this embodiment, the polyurethane foam 11 has a flat plate shape.

In this embodiment, the skin material 20 has air permeability. Specifically, the skin material 20 is made of a fiber sheet 21, and an impregnation layer 22 is formed in the skin material 20 by impregnating and curing the fiber sheet 21 with the raw material 11G of the polyurethane foam 11, and the skin material 20 including the impregnation layer 22 has air permeability. The air permeability of the skin material 20 including the impregnation layer 22 based on JIS K6400-7 B method: 2012 is preferably 3 to 90 ml/cm ² /s, and more preferably 5 to 80 ml/cm ² /s. The skin material 20 may be non-air permeable, for example, the fiber sheet 21 is impregnated with the impregnation layer 22 to become non-air permeable, or may be a resin film, etc.

In detail, the skin material 20 of this embodiment is made of two overlapping fiber sheets 21, 21. The impregnated layer 22 is formed to be approximately the same thickness as the inner fiber sheet 21A arranged on the polyurethane foam 11 side. In this embodiment, the outer fiber sheet 21B has a larger fiber diameter and basis weight than the inner fiber sheet 21A. For example, the inner fiber sheet 21A and the outer fiber sheet 21B are integrated by needle punching.

The polyurethane foam 11 of the soundproofing material 10V of this embodiment has a foam structure having a sound absorbing surface 11M and a sound absorbing path 33 similar to the polyurethane foam 11 of the soundproofing material 10 of the first embodiment. Specifically, this foam structure is provided on both sides of the polyurethane foam 11, the front and back of the skin material 20, and both sides become the sound absorbing surface 11M. Here, the foam structure having the sound absorbing surface 11M on the opposite side of the skin material 20 (the lower side of FIG. 6) of the polyurethane foam 11 has the same closed cell ratio as the first embodiment, but it is preferable that the closed cell ratio is 0.7 or less even in the foam structure having the sound absorbing surface 11M covered by the skin material 20. In this embodiment, the close cell ratio is 0.7 or less even in the sound absorbing surface 11M on the skin material 20 side, so that it is possible to particularly improve the sound absorbing performance of the polyurethane foam 11 against the sound from the skin material 20 side. Here, the closed cell ratio refers to the ratio of the number of closed cells 30B (FIG. 8) per unit cross-sectional area in the surface layer portion 10S (FIG. 7) from the sound absorbing surface 11M to a depth of 3 mm to the number of closed cells 30B (FIG. 8) per unit cross-sectional area in the central portion in the thickness direction of the polyurethane foam 11 (i.e., the portion including the central position 10D (FIG. 7) at a depth of 10 mm from the sound absorbing surface 11M covered by the skin material 20). From the viewpoint of improving the sound absorption performance for sound on the skin material 20 side, the closed cell ratio is more preferably 0.65 or less, and even more preferably 0.60 or less.

The details of the skin material 20 are as follows: Examples of fibers constituting the fiber sheet 21 include polyethylene terephthalate (PET) fibers, polyester fibers, polypropylene fibers, polyamide fibers, acrylic fibers, vinylon fibers, polyurethane fibers (spandex), glass fibers, carbon fibers, natural fibers (e.g., wool, cotton, cellulose nanofibers, etc.), Zylon (registered trademark), etc. Examples of the form of the fiber sheet 21 include nonwoven fabric, woven fabric, knitted fabric, etc. Examples of nonwoven fabric include spunlace nonwoven fabric, spunbond nonwoven fabric, and needle punch nonwoven fabric.

The fiber diameter of the fiber sheet 21 is preferably 2 to 10 denier (d), and more preferably 2 to 8 denier. The basis weight of the fiber sheet 21 is preferably 70 to 500 g/m ² , and more preferably 90 to 500 g/m ^2. When the fiber sheet 21 is made of fibers with a small fiber diameter in this manner, the distance between each of the fine fibers can be reduced to make the fibers dense, and therefore the raw material 11G of the polyurethane foam 11 is less likely to seep out of the fiber sheet 21 (skin material 20).

It is preferable that the fiber sheet 21 has 35 to 100 g/m ² of a resin other than a polyurethane resin, such as an acrylic ester resin such as ethyl acrylate or a rubber resin such as styrene-butadiene rubber (SBR). By having a resin other than a polyurethane resin adhere to the fiber sheet 21, the resin other than a polyurethane resin is interposed between the fibers, making it difficult for the raw material 11G of the polyurethane foam 11 to pass through the fiber sheet 21 (skin material 20), and making it even more difficult for the raw material 11G to seep out. The resin other than a polyurethane resin may be adhered to the surface of the fiber sheet 21 or to the fibers inside the fiber sheet 21. For example, in the latter case, the polyurethane resin constituting the impregnation layer 22 may cover the resin other than a polyurethane resin adhered to the fibers. In addition, in order to adhere a resin other than a polyurethane-based resin to the fiber sheet 21, an emulsion can be applied to the surface of the fiber sheet 21, the fiber sheet 21 can be impregnated with an emulsion, or a powder can be sprinkled on the surface of the fiber sheet 21 and then a heated roller or hot air can be applied thereto.

The air permeability of the impregnated layer 22 of the skin material 20 can be adjusted by adjusting the type of fiber constituting the fiber sheet 21, the fiber diameter, the basis weight, and the amount of resin attached other than polyurethane-based resin, such as acrylic ester-based resin.

The inner fiber sheet 21A is densely packed with fine fibers and is impregnated with an acrylic ester resin, which limits the amount of impregnation (seeping) of the raw material 11G. This ensures the breathability of the skin material 20. On the other hand, the outer fiber sheet 21B has a fiber diameter larger than that of the inner fiber sheet 21A, for example 5 denier or more, which improves the abrasion resistance of the soundproofing material 10V. In FIG. 6 and other figures, the impregnated layer 22 is shown in gray.

Next, a method for manufacturing the soundproofing material 10V of this embodiment will be described. To manufacture the soundproofing material 10V, first, raw material 11G (see FIG. 9(B)) for polyurethane foam 11 and skin material 20 are prepared. Specifically, raw material 11G for polyurethane foam 11 is prepared containing a polyol component, a polyisocyanate component, a blowing agent, a catalyst, etc., and each skin material 20 (fiber sheets 21A, 21B are integrated by needle punching) is prepared.

The raw material 11G of the polyurethane foam 11 can be the same as the raw material exemplified for the polyurethane foam 11 of the soundproofing material 10 of the first embodiment described above.

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

As shown in FIG. 9(A), the molding die 50 for molding the soundproofing material 10 consists of a lower die 51 and an upper die 52 that face each other with a cavity in between. For example, the skin material 20 is fixed to the molding surface 52M of the upper die 52. In detail, the fiber sheet 21 that becomes the inner fiber sheet 21A is arranged so that it faces the cavity side. Also, for example, the acrylic ester resin is impregnated in advance only into the inner fiber sheet 21A.

Next, as shown in Figure 9(B), raw material 11G, which is a mixture of liquids A and B, is injected into the molding recess 51U of the lower mold 51, and then the mold 50 is closed (see Figure 10(A)). The raw material 11G foams and hardens to form the polyurethane foam 11 (see Figure 10(B)). At this time, the raw material 11G impregnates the skin material 20 (specifically, the inner fiber sheet 21A) and hardens to form the impregnated layer 22, and the polyurethane foam 11 and the skin material 20 are bonded together.

The mold 50 is opened, and the integrated polyurethane foam 11 and skin material 20 are removed from the mold 50.

Next, the polyurethane foam 11 is appropriately cut, and then, as shown in FIG. 11, a blowing process is performed from the open cell surface 11MA of the polyurethane foam 11 in the same manner as in the first embodiment. As a result, the cell membrane 31 of the polyurethane foam 11 is broken, forming a broken hole 32Y, and the sound absorbing structure 40 is formed.

As shown in FIG. 12, in this embodiment, the blowing process is also performed from the skin material 20 side integrated with the polyurethane foam 11. That is, compressed gas is blown into the polyurethane foam 11 from the outside of the skin material 20, the cell membrane 31 is broken, a broken hole 32Y is formed, a sound absorbing path 33 is added, and a sound absorbing structure 40 is formed. Also, as shown in FIG. 12, this blowing process is also performed by bringing the tip surface of the nozzle N of the blow gun that ejects the compressed gas (i.e., the opening edge of the ejection port) into contact with the skin material 20. Note that the blowing process may be performed by bringing the nozzle N close to the skin material 20 (for example, by separating it by a distance of 2 mm or less). According to these methods, it becomes easier to blow the compressed gas into the polyurethane foam 11, and it becomes possible to suppress the variation in the amount of compressed gas blown in. Also, in this case, it is preferable to set the dynamic pressure of the compressed gas to be blown in to 0.1 to 1.0 MPa. This makes it easier to form a sound absorbing path to the inside of the polyurethane foam 11. The blow treatment from the skin material 20 side is performed over the entire skin material 20, but it may also be performed on only a part of the skin material 20.

Once the blowing process is complete, the soundproofing material 10V shown in Figure 6 is completed.

The soundproofing material 10V of this embodiment can achieve the same effect as the soundproofing material 10 of the first embodiment. In this embodiment, one side of the polyurethane foam 11 is covered with the skin material 20, so that the soundproofing performance of the soundproofing material 10V can be improved by the soundproofing effect or sound absorption effect of the skin material 20. In addition, by providing an impregnation layer on the skin material 20, it is possible to improve the soundproofing performance of the soundproofing material 10V and also to improve the rigidity of the soundproofing material 10V. Furthermore, since the sound absorbing structure 40 is provided on both the side of the polyurethane foam 11 facing the skin material 20 and the opposite side, it is possible to improve the sound absorbing performance against sounds from both the front and back of the polyurethane foam 11.

As shown in FIG. 13, the soundproofing material 10V of this embodiment can also be used in soundproofing structures for buildings and vehicles. For example, such a soundproofing structure can be a structure in which the soundproofing material 10V is sandwiched between a pair of sound-insulating materials 71, 72 in a state of close contact or spaced apart, as in the first embodiment. In this way, a soundproofing structure in which the soundproofing material 10V is disposed between a pair of sound-insulating materials 71, 72 can improve sound absorption and sound insulation performance.

[Third embodiment]
14, the soundproofing material 10W according to the second embodiment has a configuration in which a polyurethane foam 11 is sandwiched between a pair of skin materials 20. Specifically, the skin materials 20 are integrated with both the front and back surfaces of the polyurethane foam 11.

In this embodiment, the polyurethane foam 11 has a sound absorbing structure 40 on both the front and back sides, similar to that on the skin material 20 side in the second embodiment. The front and back skin materials 20 have an impregnated layer 22 and are breathable. The polyurethane foam 11 and the skin material 20 may be made of the same material or have the same characteristics as those exemplified in the first and second embodiments. In this embodiment, the pair of skin materials 20 have the same configuration, but they may be different. In this case, for example, the impregnated layer 22 may be provided on only one of the skin materials 20. Also, the impregnated layer 22 may not be provided on either skin material 20.

The soundproofing material 10W of this embodiment is manufactured, for example, as follows. First, as shown in Figures 15 and 16, polyurethane foam 11 is formed in the same manner as in the second embodiment. In this embodiment, skin material 20 is set on the molding surfaces of both upper and lower dies 52 and 51. At this time, the inner fiber sheets 21A of the pair of skin materials 20 are arranged so that they face each other and face the cavity side (Figure 15 (A)).

Next, raw material 11G, which is a mixture of liquids A and B, is injected into the molding recess 51U of the lower mold 51 (15(B)), after which the mold 50 is closed (Fig. 16(A)), and the raw material 11G foams and hardens to form the polyurethane foam 11 (see Fig. 16(B)). At this time, the raw material 11G impregnates the pair of skin materials 20 (specifically, the inner fiber sheet 21A) and hardens to form the impregnated layer 22, and the polyurethane foam 11 and the pair of skin materials 20 are bonded together.

Next, the integrated polyurethane foam 11 and skin material 20 are removed from the mold 50, and a blowing process is performed. Specifically, in this embodiment, the polyurethane foam 11 is blown through the skin material 20 in the same manner as in the second embodiment, and this blowing process is performed from the front and back of the polyurethane foam 11. As a result, break holes 32Y are formed on the front and back of the polyurethane foam 11, and sound absorbing paths 33 are added, forming a sound absorbing structure 40. At this time, as shown in FIG. 17, this blowing process is also performed by contacting the tip surface of the nozzle N of the blow gun that ejects compressed gas with the skin material 20, in the same manner as in the second embodiment. The blowing process may also be performed by bringing the tip surface of the nozzle N close to the skin material 20, in the same manner as in the second embodiment.

In the soundproofing material 10W of this embodiment, the sound absorbing structures 40 on the front and back of the polyurethane foam 11 can improve the sound absorbing performance of the polyurethane foam 11, thereby improving the soundproofing performance of the soundproofing material 10W. In addition, the soundproofing material 10W has skin materials 20 with impregnation layers 22 arranged on both the front and back of the polyurethane foam 11, which makes the soundproofing material 10 less likely to warp.

In this embodiment, the sound absorbing structure 40 may be provided on only one of the front and back sides of the polyurethane foam 11. Also, only one of the pair of skin materials 20 may be breathable. In this case, the other skin material 20 may be a fiber sheet that is made non-breathable by the impregnation layer 22, or may be a non-breathable resin film.

As shown in FIG. 18, the soundproofing material 10W of this embodiment can also be used in soundproofing structures for buildings and vehicles. For example, such a soundproofing structure can be a structure in which the soundproofing material 10W is sandwiched between a pair of sound-insulating materials 71, 72 in a state of close contact or spaced apart, as in the first embodiment. In this way, a soundproofing structure in which the soundproofing material 10W is placed between a pair of sound-insulating materials 71, 72 can improve sound absorption and sound insulation performance.

[Fourth embodiment]
As shown in Fig. 19, the soundproofing material 10X according to the fourth embodiment has cuts formed on one of the front and back surfaces (open cell surface 11MA) of the flat polyurethane foam 11. Specifically, a plurality of linear cuts 15 are formed on one surface of the polyurethane foam 11, and parallel linear cuts 14 consisting of these linear cuts 15 intersect at right angles to each other to form a lattice-like cut 13. In this embodiment, each linear cut 15 is arranged parallel to one side of the polyurethane foam 11 and extends from one end of the polyurethane foam 11 to the other end. The lattice-like cut 13 also extends over the entire one surface of the polyurethane foam 11.

The depth of the linear cuts 15 (i.e., the lattice-shaped cuts 13) may be to the center of the polyurethane foam 11 in the thickness direction, or to a position near one or the other of the front and back surfaces of the polyurethane foam 11. For example, in this embodiment, the skin material 20 is integrated with the other surface of the polyurethane foam 11. In this case, the depth of the cut may be deep to the boundary of the polyurethane foam 11 with the skin material 20. Also, for example, when the polyurethane foam 11 is molded, a skin layer is likely to be formed on the surface of the polyurethane foam 11. In this case, it is preferable to make the depth of the cut deeper than the skin layer of the polyurethane foam 11. This makes it easier to ventilate the polyurethane foam 11 to a position deeper than the skin layer. The skin layer of the polyurethane foam 11 is preferably breathable, i.e., the open cells 30A are open on the surface, and such a skin layer can be easily formed by using a linear hydrocarbon wax as a release agent during foam molding of the polyurethane foam 11, as described in the first embodiment.

The soundproofing material 10X of this embodiment is manufactured, for example, as follows. First, in the same manner as in the second embodiment, the skin material 20 is integrally formed on the other of the front and back surfaces of the flat polyurethane foam 11. Next, lattice-shaped cuts 13 are made in one of the front and back surfaces (exposed surface) of the polyurethane foam 11. Specifically, the surface of the polyurethane foam 11 opposite the skin material 20 is placed on top, and a stamping die having a lattice-shaped cutter is pressed against that surface from above. This forms the lattice-shaped cuts 13 in the polyurethane foam 11.

Next, a blowing process is performed in which compressed gas is blown into the exposed surface of the polyurethane foam 11. Since the cuts 13 are formed on the exposed surface of the polyurethane foam 11 as described above, it becomes easier to blow compressed gas from a blow gun into the interior of the polyurethane foam 11 through the cuts 13, making it easier to form a break hole 32Y. Note that since polyurethane foam 11 (particularly soft polyurethane foam) has high resilience, the cuts 13 may close after being formed as described above. Even in this case, however, the cuts 13 can be opened with compressed gas, making it easier to blow compressed gas into the interior of the polyurethane foam 11 through the cuts 13.

The soundproofing material 10X is obtained in this manner. Note that in this embodiment, the blowing process does not have to be performed. Also, the skin material 20 may not be provided, and the soundproofing material 10X may be composed of polyurethane foam 11 alone.

In this embodiment, by forming the cuts 13 in the polyurethane foam 11, sound (air) can easily enter the polyurethane foam 11, improving the sound absorption in the inner part of the polyurethane foam 11, and improving the sound insulation of the soundproofing material 10X. In addition, by providing the cuts 13 in the polyurethane foam 11, compressed gas can be blown into the polyurethane foam 11 through the cuts 13. This makes it easier to form the break holes 32Y, and the sound absorption of the polyurethane foam 11 can be further improved. In addition, by making such cuts in the polyurethane foam 11 to a position deeper than the skin layer, it is possible to easily allow air to circulate to a position deeper than the skin layer, and it is possible to improve the sound absorption of the polyurethane foam 11.

[Fifth embodiment]
As shown in Figures 20(A) and 20(B), in the soundproofing material 10Y according to the fifth embodiment, a plurality of puncture marks 18 are formed by piercing the polyurethane foam 11 with the tip of a needle or blade. Specifically, the polyurethane foam 11 has a flat shape, and the puncture marks 18 extend from one of the front and back surfaces (open cell surface 11MA) to the middle of the polyurethane foam 11, and these puncture marks 18 are arranged in a lattice pattern (e.g., a square lattice pattern or a staggered arrangement) with a predetermined interval between them. The plurality of puncture marks 18 may also be arranged randomly.

In the example of the soundproofing material 10Y of this embodiment, one side of the polyurethane foam 11 on which the puncture marks 18 are formed is exposed, and the other side is integrated with the skin material 20, but the puncture marks 18 may be formed on the other side and extend through the skin material 20 to the middle of the polyurethane foam 11. The soundproofing material 10Y may be composed of only the polyurethane foam 11, or the soundproofing material 10Y may be configured such that the skin material 20 is integrated on both the front and back sides of the polyurethane foam 11. In these cases, the puncture marks 18 may be formed on only one side of the polyurethane foam 11, or may be formed on both sides. When the puncture marks 18 are formed on both the front and back sides of the polyurethane foam 11, it is preferable that the needle puncture marks 18 on the front and back of the polyurethane foam 11 are shifted so as not to overlap in the thickness direction of the polyurethane foam 11. This can suppress a decrease in the rigidity of the polyurethane foam 11.

The depth of the puncture mark 18 may be to the center of the polyurethane foam 11 in the thickness direction, or to a position near one or the other of the front and back surfaces of the polyurethane foam 11. In addition, for example, when the polyurethane foam 11 is molded, a skin layer is likely to be formed on the surface of the polyurethane foam 11. In this case, it is preferable to make the depth of the puncture mark 18 to a position deeper than the skin layer of the polyurethane foam 11. This makes it easier to allow ventilation to a position deeper than the skin layer of the polyurethane foam 11. Note that the skin layer of the polyurethane foam 11 is preferably breathable, that is, the open cells 30A are preferably open on the surface, and such a skin layer can be easily formed by using a linear hydrocarbon wax as a release agent during foam molding of the polyurethane foam 11, as described in the first embodiment above.

In this embodiment, the width of the puncture mark 18 (specifically, the maximum size when viewed in the puncture direction) is equal to or greater than the cell diameter of the foamed cell 30 (specifically, the major axis, which is the length of the longest part). The thickness of the puncture mark 18 may be greater or smaller than the cell diameter of the foamed cell 30.

The soundproofing material 10Y of this embodiment is manufactured, for example, as follows. First, a polyurethane foam 11 is obtained in a flat shape with a skin material 20 integrated on one side in the same manner as in the first embodiment. Next, as shown in FIG. 21, a plurality of needle prick marks 18 are formed on one of the front and back sides (exposed surface) of the polyurethane foam 11. Specifically, the side of the polyurethane foam 11 opposite the skin material 20 is placed on the upper side, and a press mold 57 (which may be, for example, a pin holder, etc.) with a plurality of needles 58 (for example, in a lattice pattern, etc.) protruding from the lower surface is pressed against that surface from above. In this way, a piercing process in which the needles 58 are pierced halfway into the polyurethane foam 11 (more specifically, a piercing process in which the needles 58 are pierced and then removed) is performed, and the needle prick marks 18 arranged in a lattice pattern are formed. Here, because polyurethane foam 11 (especially soft polyurethane foam) has high resilience, the puncture marks 18 may close when the mold 57 is returned. Even in this case, however, the puncture marks 18 can be confirmed, for example, by magnifying the cut surface of polyurethane foam 11 with a microscope or the like.

In this embodiment, the needles 58 of the press mold 57 are, for example, as follows. The needles 58 are made up of a cylindrical body portion that is the base end side and a triangular pyramid-shaped tip portion. The diameter of the body portion of the needle 58 is 1.35 mm, and the axial length of the body portion is 9 mm. The axial length of the tip portion of the needle 58 is 4 mm. The needles 58 are arranged in a square lattice pattern, and the lattice spacing (the spacing between the central axes of adjacent needles 58) is 3.65 mm. In this embodiment, for example, the press mold 57 is pressed to such an extent that only the tips of the needles 58 are pierced into the polyurethane foam 11. The shape and arrangement of the needles 58 are not limited to this example. The piercing process may be performed by piercing the same needles 58 into multiple places without using a press mold 57 provided with multiple needles 58.

Once the piercing process is complete, a blowing process similar to that of the first embodiment is then performed on the side of the polyurethane foam 11 on which the puncture marks 18 have been formed. In this embodiment, the compressed gas can be blown into the interior of the polyurethane foam 11 through the puncture marks 18 during the blowing process, making it easier to blow the compressed gas into the interior of the polyurethane foam 11. Note that in this embodiment, the blowing process does not have to be performed.

The puncture mark 18 may penetrate the skin material 20 integrated with the polyurethane foam 11. In this case, the skin material 20 may be integrated with the other surface of the polyurethane foam 11, and the puncture mark 18 may be formed by piercing the needle 58 from the other surface (see FIG. 22). In this case, the puncture mark 18 may or may not be provided on one of the surfaces (exposed surface) of the front or back of the polyurethane foam 11.

In addition, when the piercing process to form the needle puncture marks 18 is performed from one side of the polyurethane foam 11, the cutting process to make the incisions 13 similar to the fourth embodiment described above may be performed from the other side of the polyurethane foam 11. In this case, the incisions may be linear, parallel, or lattice-shaped, and are preferably arranged so as not to overlap the puncture marks 18 when viewed from the thickness direction of the polyurethane foam 11. This makes it possible to suppress a decrease in the rigidity of the polyurethane foam 11.

In this embodiment, the needle puncture 18 is formed in the polyurethane foam 11, so that sound (air) can easily enter the polyurethane foam 11, and the sound absorption in the inner part of the polyurethane foam 11 can be improved, and the sound insulation of the soundproofing material 10Y can be improved. In addition, the puncture 18 is provided in the polyurethane foam 11, so that compressed gas can be blown into the polyurethane foam 11 through the puncture 18. This makes it easier to form the break hole 32Y, and the sound absorption of the polyurethane foam 11 can be further improved. In addition, by forming such a puncture 18 to a position deeper than the skin layer of the polyurethane foam 11, it is possible to easily allow air to pass through to a position deeper than the skin layer, and the sound absorption of the polyurethane foam 11 can be improved. The puncture 18 may be formed by piercing the polyurethane foam 11 halfway with the tip of a blade. The soundproofing material 10Y having such a puncture 18 can also improve the sound absorption.

[Other embodiments]
(1) The polyurethane foam 11 has a flat shape, but is not limited to this. For example, the polyurethane foam 11 may have a block shape such as a cube.

(2) In the above embodiment, the skin material 20 is integrated with the polyurethane foam 11 by foam molding of the polyurethane foam 11, but the skin material 20 may be laminated to the foam molded polyurethane foam 11 afterwards. In this case, the skin material 20 may be laminated on the surface of the polyurethane foam 11 that has been subjected to the blowing process.

(3) The soundproofing material 10W of the third embodiment may be manufactured by a manufacturing line as described below. Specifically, the manufacturing line is provided with a conveying means (e.g., a conveyor) that conveys the long skin materials 20 in the longitudinal direction while they are arranged opposite each other. Then, while conveying the skin materials 20, the raw material 11G of the polyurethane foam 11 is discharged between the skin materials 20, and the raw material 11G is foamed and cured to form the polyurethane foam 11. At this time, the raw material 11G of the polyurethane foam 11 is impregnated into a pair of skin materials 20, and an impregnation layer 22 is formed in each skin material 20. After that, the skin material 20 is cut to a predetermined length together with the polyurethane foam 11 by a cutter to obtain the soundproofing material 10W. Note that, if the polyurethane foam 11 protrudes from the skin materials 20 at the end in the width direction of the soundproofing material 10W, the protruding portion is appropriately trimmed. Furthermore, if a heating furnace is provided along the transport path of the transport means, the foaming and hardening of the raw material 11G of the polyurethane foam 11 can be accelerated, improving the moldability of the soundproofing material 10.

(4) The soundproofing material 10V of the second embodiment may be manufactured on the manufacturing line of the other embodiment (3). In this case, in this embodiment, only the lower skin material 20 of a pair of elongated skin materials 20 is transported on the manufacturing line of the other embodiment (3), and the raw material 11G of the polyurethane foam 11 is discharged onto the lower skin material 20 and foamed and cured.

(5) In the second and third embodiments, when the skin material 20 is made of a fiber sheet 21, the skin material 20 may be made of one fiber sheet 21 or three or more fiber sheets 21.

(6) In the second and third embodiments, the breathable skin material 20 may be a mesh-like material or may have a large number of holes running through it.

(7) In the fourth embodiment, a piercing process may also be performed. If a blowing process is to be performed, the piercing process is preferably performed before the blowing process. In the fifth embodiment, a cutting process may also be performed. If a blowing process is to be performed, the cutting process is preferably performed before the blowing process.

The above embodiment will be explained in more detail below with reference to examples and comparative examples, but the soundproofing material of the present invention is not limited to the following examples.

1. Structure and manufacturing method of soundproofing material

In Examples 1 to 4 and Comparative Examples 1 and 2, as in the manufacturing method of the above-mentioned embodiment, the raw material 11G, which is a mixture of liquid A and liquid B, is reacted to foam-mold polyurethane foam 11 (semi-rigid polyurethane foam), and the skin material 20 is integrated only on both sides of the polyurethane foam 11, to obtain a soundproofing material of a size of 500 mm x 500 mm x 20 mm (thickness). In Examples 1 to 4 and Comparative Example 2, additional processing described below was performed on the soundproofing material of that size. Note that Examples 1 to 4 and Comparative Examples 1 and 2, in which the polyurethane foam 11 is 16 mm thick and each skin material 20 is 2 mm thick, differ from each other in the presence or absence of additional processing on the polyurethane foam 11 or the type of additional processing, but the raw material 11G and skin material 20 of the polyurethane foam 11 are the same.

In Examples 1 to 4 and Comparative Examples 1 and 2, the linear hydrocarbon wax "URM-520" manufactured by Konishi Co., Ltd. was used as the release agent during foam molding.

1) Polyurethane Foam In each of the Examples and Comparative Examples, the raw material 11G of the polyurethane foam 11 is the same. The details of the composition of the raw material 11G are as follows.

<Liquid A>
Polyol 1: Polyether polyol (30 parts by weight, number average molecular weight: 5500, number of functional groups: 3.6, hydroxyl value: 31.5 mgKOH/g)
Polyol 2: Polymer polyol (70 parts by weight, number average molecular weight: 5000, number of functional groups: 3, hydroxyl value: 25 mg KOH/g, solid content concentration: 30%)
Blowing agent: water (4.35 parts by weight)
Amine catalyst 1: "Diethanolamine" (2.50 parts by weight) manufactured by Showa Chemical Co., Ltd.
Amine catalyst 2: "DABCO BL-11" (0.37 parts by weight) manufactured by Evonik Japan Co., Ltd.
Foam stabilizer: "TEGOSTAB B8715LF2" (0.50 parts by weight) manufactured by Evonik Japan Co., Ltd.
Additive: Polyether polyol (1.85 parts by weight, number average molecular weight: 5000, number of functional groups: 3, hydroxyl value: 34 mgKOH/g)
<Liquid B>
Polyisocyanate: Polymeric MDI (NCO value 31.5%)

The isocyanate index was set to 105. The isocyanate index is the value obtained by dividing the number of moles of isocyanate groups in the polyisocyanate by the number of moles of all active hydrogen groups in the polyol, blowing agent (water), etc., and multiplying the result by 100.

2) Skin Material In Example 4 and Comparative Examples 3 and 4, the skin material 20 was configured with two overlapping fiber sheets 21, 21 (an inner fiber sheet 21A and an outer fiber sheet 21B). The inner fiber sheet 21A was made of PET fiber with a fiber diameter of 3 denier and had a basis weight of 100 g/ ^m2 . The outer fiber sheet 21B was made of PET fiber with a fiber diameter of 6 denier and had a basis weight of 150 g/ ^m2 . In the skin material 20, only the inner fiber sheet 21A was impregnated with an acrylic ester resin, and the impregnation amount was 50 g/ ^m2 .

3) Types of Additional Processing Details of the additional processing carried out when producing the soundproofing materials of the examples and comparative examples are as follows.

(1) Blow Treatment In the blow treatment, compressed air was blown into the surface of the soundproofing material with the tip face of the nozzle N of the blow gun in contact with the surface. This blow treatment was performed on at least one of the front and back surfaces of the soundproofing material, and on the entire surface (hereinafter, the surface that was subjected to the blow treatment will be referred to as the blow treated surface as appropriate). The diameter of the compressed air outlet of the nozzle N of the blow gun used was 1.6 mm, and the dynamic pressure of the compressed air blown into the soundproofing material was 0.6 MPa.

(2) Piercing Process In the piercing process, similarly to the fifth embodiment, the needle 58 was pierced into a plurality of places in the soundproofing material to form a plurality of piercing marks 18 extending halfway through the polyurethane foam 11 in the thickness direction. In detail, the needle 58 is composed of a cylindrical body portion which is the base end side, and a triangular pyramid-shaped tip portion. The diameter of the body portion of the needle 58 is 1.35 mm, and the axial length of the body portion is 9 mm. The axial length of the tip portion of the needle 58 is 4 mm. The piercing marks 18 of the needle 58 are arranged in a square lattice pattern, and the lattice interval (the interval between the central axes of adjacent needles 58) is 3.65 mm. The piercing depth of the needle 58 into the soundproofing material is 4.0 mm.

(4) Roll Crushing In the roll crushing, the polyurethane foam 11 was conveyed and passed between a pair of rotating rolls to crush the entire polyurethane foam 11. The axial length of the rotating rolls was longer than 500 mm, the diameter of the rotating rolls was 200 mm, the clearance between the pair of rotating rolls was 9 mm, and the conveying speed of the polyurethane foam 11 was 70.5 mm/sec. In Comparative Examples 2 and 4, the roll crushing was performed eight times (i.e., the polyurethane foam 11 was passed between the pair of rotating rolls eight times). In detail, the roll crushing was performed once in each of four arrangements (i.e., arrangements rotated by 90 degrees) in which each side of the polyurethane foam 11 was parallel to the rotating rollers and at the front of the conveying direction, a total of four times. Furthermore, the polyurethane foam 11 was turned over and then roll crushed four times in the same manner.

4) Details of the additional processing of each embodiment and each comparative example Details of the additional processing of each embodiment and each comparative example are as follows. Note that, hereinafter and in Fig. 24, either one of the front and back surfaces of the soundproofing material will be appropriately referred to as the first surface, and the other surface will be appropriately referred to as the second surface.

Example 1
Both the first and second surfaces (both the front and back) were subjected to blow treatment only.
Example 2
The first surface was subjected to only the blowing treatment, and the second surface was subjected to only the piercing treatment.
Example 3
The first surface was only subjected to a blowing treatment, and the second surface was not subjected to any additional processing.
Example 4
The first surface was subjected to blow treatment only, and the second surface was subjected to piercing treatment and then blow treatment.
Example 5
The first surface was only pierced, while the second surface was pierced and then blown.
Example 6
No additional processing was performed on the first surface, and the second surface was subjected to a piercing process and then a blowing process.
Example 7
Both the first and second surfaces were subjected to a piercing treatment and then a blowing treatment.
<Comparative Example 1>
No additional processing has been performed on the soundproofing material, and therefore no breakage hole 32Y has been formed.
<Comparative Example 2>
Only roll crushing was performed.

2. Evaluation Each of the examples and comparative examples was evaluated for appearance, closed cell ratio, hardness, reverberation room sound absorption coefficient, transmission loss, etc. The measurement methods for the measurement items are as follows.

<Measurement method>
(1) Density The apparent density of the polyurethane foam 11 was measured based on JIS K7222: 2005. Specifically, a test piece of 500 mm × 500 mm × 20 mm (thickness) was cut into a test piece of 100 mm × 100 mm × 20 mm (thickness) and the measurement was performed.

(2) Airflow The airflow was measured based on JIS K6400-7 B method: 2012. Specifically, the soundproofing material was sliced so as to divide the polyurethane foam 11 in the thickness direction to obtain three slice samples (100 mm square), and the air was passed from the bottom to the top to measure the airflow. In detail, the slice samples were a 4 mm thick portion (central slice sample) in the thickness direction of the polyurethane foam 11, the skin material 20 on the first surface side, and the skin material 20 on the second surface side. The central slice sample (polyurethane foam 11) was ventilated from the second surface side (the second surface side was placed on the lower side), and the latter two slice samples (skin material 20) were ventilated from the impregnated layer 22 side (the impregnated layer 22 side was placed on the lower side) to measure the airflow.

(3) Closed cell ratio A scanning electron microscope (SEM: manufactured by JEOL Ltd.) was used to observe a region of a predetermined area (center region D and surface region S in FIG. 2) in the center and surface layer portion 10S of the outer peripheral surface 11E of the polyurethane foam 11, and the number of closed cells 30B in the predetermined area was counted. The ratio of the number of closed cells 30B in the surface region S to the number of closed cells 30B in the thickness direction of the polyurethane foam 11 was determined as the closed cell ratio. The center region D was determined so that the center position in the thickness direction of the polyurethane foam 11 was the center of the center region D, and the surface region S was determined so that it was within a range of 3 mm deep from the surface in the thickness direction of the polyurethane foam 11. The predetermined area observed by the SEM in the center region D and the surface region S was 2.5 mm x 2.5 mm. A low closed cell ratio means that the number of closed cells is smaller on the surface side than inside the polyurethane foam 11. The magnification of the SEM was 35 times.

The closed cell ratio was evaluated as ◎ if it was 0.7 or less, ○ if it was greater than 0.7 and less than 1.0, and × if it was greater than 1.0.

(4) Cell diameter A scanning electron microscope (SEM: manufactured by JEOL Ltd.) was used to measure the average major axis and the average minor axis of the largest foamed cell 30, the smallest foamed cell 30, and any three other foamed cells 30 among the foamed cells 30 captured in an enlarged image of the central portion (central region D (see FIG. 2)) in the thickness direction of the outer peripheral surface 11E of the polyurethane foam 11. The ratio of the average major axis to the average minor axis (major axis/minor axis) was calculated from the average major axis and the average minor axis of the five foamed cells, that is, the largest foamed cell 30, the smallest foamed cell 30, and any three other foamed cells 30. The major axis of the foamed cell 30 is the length of the longest part of each foamed cell 30 observed by SEM, and the minor axis of the foamed cell 30 is the length of the shortest part of each foamed cell 30 observed by SEM. The magnification of the SEM was 35 times.

The above-mentioned major axis/minor axis value of the foam cells 30 was evaluated as ⊚ when it was 1 or more and 1.5 or less, and as × when it was more than 1.5.

(5) Deformation due to additional processing The deformation of the soundproofing material was confirmed before and after the additional processing. Specifically, the thickness of the test piece was measured before and after the additional processing, and the change was confirmed. The thickness of the test piece was measured at three points (both ends and the center) on each of the four sides of the test piece, and the average value of the thicknesses at these 12 points was used.

The thickness of the soundproofing material after additional processing was evaluated as ◎ if it was 19 mm or more, ○ if it was 18 mm or more but less than 19 mm, and × if it was less than 18 mm. As mentioned above, the thickness of the soundproofing material before additional processing was 20 mm.

(6) Hardness The hardness of the polyurethane foam 11 was measured based on JIS K6400-2 E method: 2012. Specifically, a test piece of 500 mm x 500 mm x 20 mm was cut to 200 mm x 200 mm x 20 mm, and the test piece was compressed from above with a compression tool (the pressing surface is a circle with a diameter of 80 mm) at a compression speed of 50 mm/min until the deformation in the thickness direction became 80% of the original thickness of the test piece, and the load at 50% compression (50% compression hardness) was measured. The soundproofing material was arranged so that the first surface was facing upward.

The 50% compression hardness was evaluated as ◎ if it was 500N or more, and × if it was less than 500N.

(7) Transmission loss The transmission loss was measured based on JIS A1441-1:2007. Specifically, a test piece was placed on an iron plate (500 mm x 500 mm x 0.8 mm (thickness)), and a rubber plate (500 mm x 500 mm x 1.0 mm (thickness)) was placed on top of the test piece to prepare a measurement sample. The soundproofing material was arranged so that the first surface faced upward.

Transmission loss was evaluated as ◎ if it was 50 dB or more, ○ if it was 48 dB or more but less than 50 dB, and × if it was less than 48 dB.

(8) Reverberation Room Sound Absorption Coefficient Based on JIS A1409:1998, the reverberation room sound absorption coefficient of the test pieces of the soundproofing material was measured. Specifically, four test pieces measuring 500 mm x 500 mm x 20 mm (thickness) were laid on the floor of a reverberation room to form a measurement sample measuring 1 m x 1 m x 20 mm, and the reverberation room sound absorption coefficient at each frequency was measured. At this time, the outer periphery of the measurement sample was covered with an aluminum fixture, and the test pieces and the gaps between the test pieces and the fixture were sealed with aluminum tape. The sound absorption coefficients at frequencies of 500, 630, 800, 1000, 1250, 1600, 2000, 2500, 3150, 4000, 5000, and 6300 Hz were measured both with the first surface facing upward and with the second surface facing upward, and the average of all these measured values was taken as the reverberation chamber sound absorption coefficient of the test piece.

The reverberation chamber sound absorption coefficient was evaluated as ◎ if it was 0.50 or more, ○ if it was 0.45 or more and less than 0.50, and × if it was less than 0.45.

If all of the above evaluation items are ◎, the overall evaluation is "◎", if there are ○ but no ×, the overall evaluation is "○", and if there is even one ×, the overall evaluation is "×".

<Evaluation Results>
As shown in FIG. 24, it was confirmed that in Examples 1 to 7 in which a blow treatment was performed as an additional process, the reverberation chamber sound absorption coefficient was significantly improved compared to Comparative Examples 1 and 3 in which no additional process was performed (rating ◎). In Examples 1 to 7, the transmission loss was also better than Comparative Examples 1 and 3 (rating ○ or higher). In addition, as can be seen from the comparison between Example 1 and Example 3, it was found that the improvement in the reverberation chamber sound absorption coefficient was greater when the blow treatment was performed from both sides of the soundproofing material than from only one side. In addition, as can be seen from the comparison between Example 1 and Example 4, and the comparison between Example 1 and Example 7, it can be seen that the reverberation chamber sound absorption coefficient is greater when the blow treatment is performed after the piercing treatment as an additional process than when only the blow treatment is performed.

In Comparative Example 2, in which roll crushing was performed as additional processing, the reverberation chamber sound absorption rate and transmission loss were improved compared to Comparative Example 1, in which no additional processing was performed, but the polyurethane foam 11 was significantly deformed by roll crushing. Specifically, the polyurethane foam 11 was crushed by roll crushing, and the thickness of the polyurethane foam 11 became thinner (see thickness after additional processing). In Comparative Example 2, as can be seen from the comparison of the 50% compression hardness with Comparative Example 1, it has become harder. Therefore, it can be seen that when roll crushing is performed, the soundproofing material is difficult to restore and the dimensional accuracy is reduced. In Comparative Example 2, as can be seen from the major axis/minor axis ratio of the cell diameter, the foam cells 30 are longer than those of Examples 1 to 7 and Comparative Example 1. This is thought to be because the foam cells 30 are crushed by roll crushing.

In contrast, in Examples 1 to 7, in which the blowing process was performed without roll crushing, no deformation of the polyurethane foam 11 was observed, even in Comparative Example 1, in which no additional processing was performed, and the hardness of the polyurethane foam 11 was also approximately the same (both the thickness after additional processing and the 50% compression hardness were rated as excellent). Thus, it was found that the soundproofing materials of Examples 1 to 7 can improve sound absorption while preventing a deterioration in dimensional accuracy due to additional processing.

As described above, it was confirmed that the soundproofing materials of Examples 1 to 7, which were blow-treated, were able to improve sound absorption while preventing a decrease in dimensional accuracy compared to the soundproofing materials of Comparative Examples 1 and 2 (overall evaluation of ○ or higher).

REFERENCE SIGNS LIST 10 Soundproofing material 11 Polyurethane foam 13 Cut 18 Puncture mark 30 Foam cell 30A Open cell 30B Closed cell 31 Cell membrane 32 Cell hole 32X Foam hole 32Y Broken hole 33 Sound absorbing path

Claims (10)

A method for producing a soundproofing material comprising polyurethane foam, comprising the steps of:
The polyurethane foam is integrated with a pair of breathable skin materials so that the polyurethane foam is sandwiched between the pair of breathable skin materials;
A method for manufacturing a soundproofing material, comprising the steps of: performing a blowing process in which compressed gas is blown into the interior of the foamed polyurethane foam through the skin material, thereby forming additional break holes in the cell membranes of a plurality of foam cells contained in the polyurethane foam. The method for manufacturing soundproofing material according to claim 1, wherein the blowing process is performed by bringing the tip face of a nozzle that ejects the compressed gas into contact with or close to the surface of the skin material. The method for manufacturing soundproofing material according to claim 2, wherein the dynamic pressure of the compressed gas is 0.1 to 1 MPa. The method for producing a soundproofing material according to any one of claims 1 to 3, in which a piercing process is performed in which the tips of multiple needles or blades are pierced through the skin material into the surface of the polyurethane foam before the blowing process. A soundproofing material comprising polyurethane foam,
the polyurethane foam and a pair of breathable skin materials are integrated together such that the polyurethane foam is sandwiched between the pair of breathable skin materials;
The polyurethane foam has a cell membrane having a plurality of foam cells, and the cell membrane has a rupture hole formed therein.
A soundproofing material in which the number of closed cells among the foam cells is smaller toward the surface where the skin material is integrated than toward the inside of the polyurethane foam. A soundproofing material comprising polyurethane foam,
the polyurethane foam and a pair of breathable skin materials are integrated together such that the polyurethane foam is sandwiched between the pair of breathable skin materials;
The polyurethane foam has a cell membrane having a plurality of foam cells, and the cell membrane has a rupture hole formed therein.
A soundproofing material in which the amount of air permeability of the polyurethane foam is greater closer to the surface where the skin material is integrated than to the interior of the polyurethane foam. The polyurethane foam has a flat shape, and the skin material is integrated on both the front and back sides of the polyurethane foam.
7. The soundproofing material according to claim 5, wherein the ratio of the number of closed cells per unit cross-sectional area in the central portion of the polyurethane foam in the thickness direction to the number of the closed cells per unit cross-sectional area in the surface portion up to a depth of 3 mm from both the front and back surfaces of the polyurethane foam is 0.7 or less. The soundproofing material according to any one of claims 5 to 7, wherein the ratio of the number of open cells to the total number of foam cells is greater closer to the surface where the skin material is integrated than to the interior of the polyurethane foam. The soundproofing material according to any one of claims 5 to 8, wherein the rupture holes are formed by rupturing the cell membrane due to the wind pressure of compressed gas blown into the polyurethane foam through the skin material. The soundproofing material according to any one of claims 5 to 9, wherein the 50% compression hardness of the polyurethane foam based on the E method of JIS K6400-2:2012 is 500N to 3000N.

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