JP6966774B2 - Sound absorbing material - Google Patents

Description

The present invention relates to a sound absorbing material for reducing noise generated in a vehicle, a factory, a concert hall, a room of a general household, etc., and more specifically, by having a specific seat structure, the sound absorbing coefficient is significantly improved. Regarding sound absorbing materials.

From the viewpoint of living environment and working environment, the required level of noise control is increasing year by year, and there is a demand for sound absorbing materials that are lightweight and have excellent environmental friendliness and handling, and various sound absorbing materials have been developed. ing.

Patent Document 1 discloses a lightweight interior material exhibiting a sound absorbing effect and the like, using a foam such as a polystyrene resin, a polypropylene resin, a polyethylene resin, a polyurethane resin, and a polyvinylidene chloride resin as a substrate.
However, such an interior material is not sufficient in terms of sound absorption performance, and it is difficult to handle because the foam is bulky. Further, although the foam of polyurethane resin is relatively excellent in sound absorption performance, it is not preferable from the viewpoint of environmental friendliness because cyanide is generated at the time of combustion, and in recent years, it has tended to be de-urethane.

Patent Document 2 discloses an outdoor sound absorbing material in which an organic fiber non-woven fabric and an inorganic fiber such as glass fiber are laminated.
The sound absorbing material using glass fiber may be difficult to handle because it irritates the skin and the sound absorbing material becomes heavy due to its high density.

Patent Document 3 discloses a fiber laminated sound absorbing material in which two kinds of organic fiber non-woven fabrics having different apparent densities are laminated.
Such a mat-like sound absorbing material has a problem that the surface is flat and lacks aesthetics.

Since the required level of noise control is increasing, it is required to develop a sound absorbing material having excellent sound absorbing property by eliminating the above-mentioned drawbacks of the conventional sound absorbing material.

Japanese Unexamined Patent Publication No. 9-268736 Japanese Unexamined Patent Publication No. 2001-271438 Japanese Unexamined Patent Publication No. 11-293804

The present invention has been made in view of the above background technology, and the present invention provides a sound absorbing material having features such as excellent sound absorption; light weight and easy handling; less environmental load; excellent aesthetics; There is something in it.

As a result of diligent studies to solve the above problems, the present inventor has made three layers: a sound absorbing side sheet layer, a back side sheet layer, and an intermediate layer sandwiched between the sound absorbing side sheet layer and the back side sheet layer. We have found that a sound absorbing material having excellent sound absorbing properties can be obtained by forming the sound absorbing side sheet layer with a specific concavo-convex structure and using a material having a low air permeability. The present invention has been completed.

That is, the present invention is composed of a sound absorbing side sheet layer, a back side sheet layer, and an intermediate layer sandwiched between the sound absorbing side sheet layer and the back side sheet layer, and the sound absorbing side sheet layer has a convex portion and a convex portion. A sound absorbing material having an uneven structure consisting of linear recesses.
On the surface of the sound absorbing side sheet layer, the density ^{of the recesses is 10 m / m 2} or more and 400 m / m ² or less, and the air permeability of the sound absorbing side sheet layer is 0.31 ^{cm 3} / cm ² · s or less. It provides a characteristic sound absorbing material.

According to the present invention, it is possible to provide a sound absorbing material having excellent sound absorbing properties. Further, the sound absorbing material of the present invention is lightweight, thin, and can be stored in a roll shape, so that it is easy to handle and can be easily installed on an inner wall or the like.

Unlike the conventional sound absorbing material, the sound absorbing material of the present invention can avoid using polyurethane resin or glass fiber, so that it is less likely to give an environmental load. Further, since the sound absorbing material of the present invention uses only a soft material, it is rich in cushioning property and is safe even if a human collides with it.
Further, the sound absorbing material of the present invention can exhibit excellent aesthetics due to the beautiful surface of the three-dimensional structure. The uneven structure can be made into various shapes, and the appearance can be made rich in taste.

It is an example of the plan view of the sound absorbing material of this invention. It is an example of the sectional view of the sound absorbing material of this invention. It is a graph which shows the sound absorption coefficient of the sound absorbing material of Example 1. FIG. It is a graph which shows the sound absorption coefficient of the sound absorbing material of Example 2. It is a graph which shows the sound absorption coefficient of the sound absorbing material of the comparative example 1. FIG.

Hereinafter, the present invention will be described, but the present invention is not limited to the following embodiments, and can be arbitrarily modified and carried out.

A plan view of the sound absorbing material of the present invention is shown in FIG. 1, and a cross-sectional view is shown in FIG. The sound absorbing material 1 of the present invention is composed of three layers: a sound absorbing side sheet layer 10, a back side sheet layer 20, and an intermediate layer 30 sandwiched between the sound absorbing side sheet layer 10 and the back side sheet layer 20.

The sound absorbing side sheet layer 10 is a sheet layer on the side that faces the direction of the sound source when the sound absorbing material 1 is used. For example, when the sound absorbing material 1 is attached to the inner wall of the room, the sound absorbing side sheet layer 10 is a layer on the visible side.
The sound absorbing side sheet layer 10 has an uneven structure including a convex portion 11 and a linear concave portion 12.
The back side sheet layer 20 is a sheet layer on the opposite side to the sound absorbing side sheet layer 10, and an intermediate layer 30 is provided between the back side sheet layer 20 and the sound absorbing side sheet layer 10.

Generally, the sound absorbing mechanism by various sound absorbing materials is (a) a porous type sound absorbing mechanism in which a part of the sound energy is consumed as heat energy in the pores of a fiber sheet or the like, and (b) an airtight such as a cambus. Plate (film) vibration type sound absorption that consumes sound energy due to plate vibration and internal friction of film vibration when sound hits the material, (c) When sound hits a resonator with a hole in the cavity, at the hole part There are three types of resonator-type sound absorption in which air vibrates and is consumed as frictional heat.
The sound absorbing material 1 of the present invention is a material in which the sound absorbing side sheet layer 10 is difficult for sound to pass through, and has an uneven structure. In the sound absorbing material 1 of the present invention, it is presumed that the sound absorbing effect of the membrane vibration type sound absorbing, in which sound waves collide with the surface of the sound absorbing side sheet layer 10 and the convex portions vibrate minutely, and sound energy is consumed, is dominant. NS.

The material constituting the sound absorbing side sheet layer 10 is a material having a low air permeability. Specifically, the air permeability of the sound absorbing side sheet layer 10 is 0.31 ^{cm 3} / cm ² · s or less (Note that 0.31 ^{cm 3} / cm ² · s is JIS L1096: 2010 “woven fabric and knitted fabric). It is the lower limit of measurement in the "breathability" A method (Frazier type method) of the "fabric test method"). That is, the sound absorbing side sheet layer 10 has almost no air permeability.

When the sound absorbing side sheet layer 10 is made of a breathable material, sound waves pass through the sound absorbing side sheet layer 10 and collide with the sheet-like fibers contained in the intermediate layer 30 to exert a sound absorbing effect. However, when the sound absorbing side has an uneven structure as in the present invention, the sound absorbing effect by repeatedly colliding sound waves with the surface of the sound absorbing side sheet layer 10 is better than the sound absorbing effect by the intermediate layer 30. The fact that it is significantly larger is a new finding obtained by the present inventor.
The human ear has particularly good sensitivity in the vicinity of 1000 to 5000 Hz, but by forming the sound absorbing side sheet layer 10 with a material having almost no air permeability, the sound absorbing effect in such a frequency range is likely to be improved.

Specifically, the sound absorbing side sheet layer 10 is preferably made of synthetic leather, artificial leather, natural leather or a polymer film. By using these materials, it is easy to reduce the air permeability to 0.31 ^{cm 3} / cm ² · s (almost zero).
In the case of synthetic leather, its surface layer is preferably polyvinyl chloride or polyurethane.
Examples of the polymer film include a polyethylene film, a polypropylene film, a polyvinyl chloride film, a polyester film, a polyamide film, a polyimide film, and a polycarbonate film.

The recess 12 is a portion where the sound absorbing side sheet layer 10 and the back side sheet layer 20 are in direct contact with each other, and exists linearly on the surface of the sound absorbing side sheet layer 10. In the convex portion 11 of the sound absorbing side sheet layer 10, an intermediate layer 30 containing sheet-shaped fibers is sandwiched between the sound absorbing side sheet layer 10 and the back side sheet layer 20.

The shape of the concave-convex structure in the sound-absorbing side sheet layer 10 is not particularly limited, and the structure shown in FIG. 1 can be exemplified (FIG. 1 (a): the shape of the convex portion 11 is a rhombus, and FIG. 1 (b): the shape of the convex portion 11. 1 (c): the shape of the convex portion 11 is an ellipse, and FIG. 1 (d): the shape of the convex portion 11 is a semi-cylindrical shape).

The method for forming the uneven structure is not particularly limited, but it can be formed by a known method such as quilting (quilting). The structures exemplified by FIGS. 1 (a) to 1 (d) are shapes that can be easily formed by quilting.
The recess 12 can be in a state of being quilted with a sewing thread or ultrasonic waves.

The density of the linear recesses 12 on the surface of the sound absorbing side sheet layer 10 (value obtained by dividing the total length of the recesses 12 by the surface area of the surface of the sound absorbing side sheet layer 10 on the sound absorbing side) is 10 m / m ² or more and 400 m / It is m ² or less.
The density of the recesses 12, 20 m / ^{m 2} or more preferably, 40 m / ^{m 2} or more is particularly preferable. Further, 300 m / m ² or less is preferable, and 200 m / m ² or less is particularly preferable.
When the density of the recess 12 is within the above range, the sound absorption property (particularly, the sound absorption property at 1000 to 5000 Hz, which is particularly sensitive to the human ear) is likely to be improved. When it is at least the above lower limit, the number of collisions of sound waves on the surface can be sufficiently secured, so that the sound absorption property is likely to be improved. Further, when it is not more than the above upper limit, as will be described later, when the back side sheet layer 30 is heated and shrunk, the recess 11 is sufficiently expanded, so that the sound absorption property is likely to be improved.

The average thickness of the sound absorbing side sheet layer 10 is preferably 0.1 mm or more, more preferably 0.2 mm or more, and particularly preferably 0.3 mm or more. Further, it is preferably 2 mm or less, more preferably 1.8 mm or less, and particularly preferably 1.5 mm or less.
When it is at least the above lower limit, there is little damage when the concave portion 12 is formed by quilting or the like, sound waves can be sufficiently made to collide with the sound absorbing side sheet layer 10, and the sound absorbing property is improved. When it is not more than the above upper limit, it is advantageous in terms of cost, and the sound absorbing material can be made lighter.
The sound absorbing side sheet layer 10 is formed with a recess 12 by quilting or the like, but the average thickness of the sound absorbing side sheet layer 10 hardly changes before and after the quilting process.

_{The difference between the height of the highest point (H 1} in FIG. 2) and the height of the lowest point (H ₂ in FIG. 2) of the uneven structure in the sound absorbing side sheet layer 10 is preferably 1 mm or more, and is preferably 3 mm or more. It is more preferable, and it is particularly preferable that it is 5 mm or more. Further, it is preferably 20 mm or less, more preferably 15 mm or less, and particularly preferably 12 mm or less.
When it is at least the above lower limit, the sound wave can be sufficiently collided with the sound absorbing side sheet layer 10, and the sound absorbing property is likely to be improved. Further, as described later, the sound absorbing material 1 of the present invention can be produced by inflating the sound absorbing side sheet layer 10 by shrinking the back side sheet layer 30 by heating, but in the case of producing by such a method. , It is easy to manufacture a product in which the difference between the height of the highest point and the height of the lowest point is equal to or less than the above upper limit.

The surface of the sound absorbing side sheet layer 10 can be made excellent in aesthetics by imparting uneven structures having various shapes, but can be made further excellent in aesthetics by coloring the surface or the like. be able to.

The intermediate layer 30 is a layer between the sound absorbing side sheet layer 10 and the back side sheet layer 20, and contains sheet-like fibers. The intermediate layer 30 contributes to the cushioning property of the sound absorbing material 1. It also contributes to sound absorption.
As will be described later, when the back side sheet layer 30 is shrunk by heating, the fiber sheet contained in the intermediate layer 30 is extruded toward the sound absorbing side sheet layer 10, and the convex portion 11 of the sound absorbing side sheet layer 10 becomes high. As a result, since the surface area per unit area of the sound absorbing side sheet layer 10 becomes large, sound waves easily collide with the surface, and the sound absorbing property is improved.

The fibers constituting the intermediate layer 30 may be organic fibers or inorganic fibers. Further, it may be a short fiber or a long fiber.
Specific examples of the fibers constituting the intermediate layer 30 include polyester, nylon, acrylic, vinylon, rayon, aramid, cotton, wool, glass fiber and the like. These may be used alone or in combination of two or more.

The back side sheet layer 20 is integrated with the sound absorbing side sheet layer 10 in the recess 12 by quilting or the like.
The back sheet layer 20 is made of, for example, a woven fabric, a knitted fabric, or the like.
Moreover, as a material of the back side sheet layer 20, acrylic fiber, polyester fiber and the like can be mentioned.

The back sheet layer 20 preferably shrinks when heated.
The sound absorbing material 1 of the present invention can be produced by performing quilting or the like in a state where the fiber sheet constituting the intermediate layer 30 is sandwiched between the sound absorbing side sheet layer 10 and the back side sheet layer 20. By heating in this state, the back side sheet layer 20 contracts, the fiber sheet contained in the intermediate layer 30 is pushed out to the side of the sound absorbing side sheet layer 10, and the convex portion 11 of the sound absorbing side sheet layer 10 becomes high. As a result, the sound absorption property is improved.

When the back sheet layer 20 shrinks due to heating, the shrinkage rate is preferably 20% or more, particularly preferably 25% or more when it is dry-heated at 150 ° C. for 5 minutes. Further, it is preferably 50% or less, and particularly preferably 40% or less.
Within the above range, the convex portion 11 becomes sufficiently high, and the sound absorbing material is less likely to be distorted.

The temperature at which the sound absorbing material 1 is heated to shrink the back sheet layer 20 is preferably 110 ° C. or higher, and particularly preferably 140 ° C. or higher. Further, it is preferably 200 ° C. or lower, and particularly preferably 180 ° C. or lower.
The heating time is preferably 1 minute or longer, and particularly preferably 2 minutes or longer. Further, it is preferably 30 minutes or less, and particularly preferably 15 minutes or less.
When the heating temperature and the heating time are within the above ranges, the convex portion 11 sufficiently swells to easily improve the sound absorption property, and the cost can be suppressed.

The method for installing the sound absorbing material 1 of the present invention is a method of gluing to the installation surface, a method of fixing to the installation surface using a tacker, a method of attaching with a hook-and-loop fastener, and fitting in a panel of A1 size or the like. There is a method of installing it like a painting.
Since the back sheet layer 20 is made of a woven fabric or a knitted fabric, it can be easily installed by such a method.

The basis weight of the sound absorbing material 1 of the present invention ^{is preferably 650 g / m 2} or more, more preferably 750 g / m ² or more, and ^{particularly preferably 850 g / m 2} or more. Further, it is preferably 3000 g / ^{m 2} or less, more preferably 2400 g / ^{m 2} or less, particularly preferably 1500 g / ^{m 2} or less.
When the lower limit of the basis weight is equal to or higher than the above, sufficient strength can be obtained and the sound absorption performance becomes excellent. When the upper limit is less than or equal to the above, it is sufficiently lightweight and easy to handle.

The sound absorbing material 1 of the present invention is used indoors or the like, and it is desirable that the sound absorbing material 1 is made flame-retardant by a known method.
As the flame retardant, known flame retardants such as phosphorus-based flame retardants, nitrogen-based flame retardants, sulfur-based flame retardants, boron-based flame retardants, and halogen-based flame retardants can be appropriately used.

Although the action / principle of the sound absorbing material of the present invention exhibiting excellent sound absorbing properties is not clear, the following can be considered. However, the present invention is not limited to the following scope of action / principle.
In the sound absorbing material of the present invention, the sound absorbing side sheet layer 10 is made of a material having almost no air permeability, and the sound absorbing side sheet layer 10 has an uneven structure. By densely providing the uneven structure, sound waves collide with the concave portion 12 many times on the surface of the sound absorbing side sheet layer 10, causing the convex portion 11 to vibrate minutely, and the energy is converted into heat to exert a sound absorbing effect. It is thought that it is doing.
Further, as is clear from the comparative example described later, when the sound absorbing side sheet layer is made of a highly breathable material, the sound absorbing property hardly changes even if the uneven structure is made dense. That is, it is considered that the effect of the sheet-shaped fibers constituting the intermediate layer 30 on the sound absorption property is small, and the sound absorption side sheet layer 10 having almost no air permeability greatly contributes to the sound absorption property.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples as long as the gist thereof is not exceeded.

Example 1
As described below, a sound absorbing material (see Table 1 for the density of the concave portions 12) 1 having a diamond-shaped convex portion 11 as shown in FIG. 1 (a) was produced.

Synthetic leather with polyvinyl chloride (manufactured by Tokyo Shinko Leather Co., Ltd., product name: light, grain: 569 g / m ² , thickness: 0.96 mm) and high-shrink acrylic fiber woven fabric (Nm (hair count): 2) / 32, warp: 20 yarns / inch, weft: 20 yarns / inch, basis weight: 101g / ^{m 2,} thickness: between 0.38 mm), in a state sandwiched a sheet of polyester staple 340 g / ^{m 2,} Sewing threads were sewn onto the synthetic leather and the woven fabric by a quilting machine.
Then, by drying and heating at 150 ° C. for 5 minutes, the woven fabric which is the back side sheet layer 20 is shrunk, and the convex portion 11 of the sound absorbing side sheet layer 10 whose surface layer is synthetic leather of polyvinyl chloride is inflated to expand the sound absorbing material 1. Was produced.
The air permeability of the synthetic leather of polyvinyl chloride measured according to the JIS L1096: 2010 A method was 0.31 ^{cm 3} / cm ² · s (measurement limit) or less.

The produced sound absorbing material 1 was cut into a circular shape having a diameter of 100 mm and used as a sample for measuring the sound absorbing coefficient.
The number of the projections 11 of the rhombic shape with respect to each sample was measured density of the linear recess 12, the height H ₁ of the highest point of the concave-convex _structure, the lowest point of the concave-convex structure height H ₂ (Table 1).

For each sample, the vertical incident sound absorption coefficient was measured in the range of 50Hz to 1600Hz in accordance with JIS A 1405-2: 2007 "Measurement of sound absorption coefficient and impedance by acoustic tube-Part 2: Transfer function method" (test). Device name: B & K4206, 3560D).
The results are shown in FIG.

Example 2
As described below, a sound absorbing material 1 having a rhombus-shaped convex portion 11 as shown in FIG. 1A was produced.

Using the same synthetic leather, high shrinkage acrylic fiber woven fabric, and polyester staple sheet as in Example 1, the synthetic leather and the woven fabric are convex with the sheet sandwiched between the synthetic leather and the woven fabric. It was sewn with a sewing thread so that the number of portions 11 was 7 (the density of the recesses 12 was 82 m / m ^2).
Then, by drying and heating under the conditions shown in Table 2, the woven fabric which is the back side sheet layer 20 is shrunk, and the convex portion 11 of the sound absorbing side sheet layer 10 whose surface layer is polyvinyl chloride synthetic leather is inflated to absorb sound. Material 1 was produced.

The produced sound absorbing material 1 was cut into a circular shape having a diameter of 100 mm and used as a sample for measuring the sound absorbing coefficient.
For each sample, the height H _{1 of the highest point of the uneven structure and the height H 2} of the lowest point of the uneven structure were measured (Table 2).

For each sample, the vertical incident sound absorption coefficient was measured in the range of 50 Hz to 1600 Hz in accordance with JIS A 1405-2: 2007.
The results are shown in FIG.

Comparative Example 1
^{Except for the use of polyester knitted fabric (grain: 160 g / m 2} , thickness: 0.96 mm, tricot with 110 dtex, wale: 28 / inch, course: 37 / inch) instead of synthetic leather in Example 1. In the same manner as in Example 1, a sound absorbing material 1 having a diamond-shaped convex portion 11 as shown in FIG. 1A was produced.
The air permeability of the polyester knitted fabric measured according to the JIS L1096: 2010 A method was 265.2 ^{cm 3} / cm ² · s.

The produced sound absorbing material 1 was cut into a circular shape having a diameter of 100 mm and used as a sample for measuring the sound absorbing coefficient.
The number of the projections 11 of the rhombic shape with respect to each sample was measured density of the linear recess 12, the height H ₁ of the highest point of the concave-convex _structure, the lowest point of the concave-convex structure height H ₂ (Table 3).

For each sample, the vertical incident sound absorption coefficient was measured in the range of 50 Hz to 1600 Hz in accordance with JIS A 1405-2: 2007.
The results are shown in FIG.

As is clear from FIGS. 3 to 5, when the sound absorbing side is made of a material having almost no air permeability, the density of the recess 12 becomes large (that is, the frequency at which the sound absorbing rate is maximum) at the peak of the sound absorbing rate (that is, the frequency at which the sound absorbing rate is maximized). As the uneven structure becomes denser), the sound absorbing material shifts to the higher frequency side, and a sound absorbing material having a peak sound absorbing coefficient near 800 to 1200 Hz, which has good sensitivity of the human ear, can be obtained.
On the other hand, when the sound absorbing side was made of a highly breathable material, the sound absorbing rate increased as the frequency increased, but the density of the recess 12 on the sound absorbing property had almost no effect.

The sound absorbing material of the present invention is lightweight, easy to handle, does not give an environmental load, and has excellent aesthetics, so that it is widely used for noise control in vehicles, factories, concert halls, general households, and the like.

1 Sound absorbing material 10 Sound absorbing side sheet layer 11 Convex part 12 Concave part 20 Back side sheet layer 30 Intermediate layer

Claims (11)

It is composed of a sound absorbing side sheet layer, a back side sheet layer, an intermediate layer sandwiched between the sound absorbing side sheet layer and the back side sheet layer, and the sound absorbing side sheet layer is composed of a convex portion and a linear concave portion. It is a sound absorbing material with an uneven structure.
On the surface of the sound absorbing side sheet layer, the density of the recesses is 20 m / m ² or more and 200 m / m ² or less, and the air permeability of the sound absorbing side sheet layer is 0.31 ^{cm 3} / cm ² · s or less. A sound absorbing material characterized by that. The sound absorbing material according to claim 1, wherein the sound absorbing side sheet layer is made of synthetic leather, artificial leather, natural leather or a polymer film. The sound absorbing material according to claim 1 or 2, wherein the difference between the height of the highest point and the height of the lowest point of the uneven structure is 1.0 mm or more and 20 mm or less. The sound absorbing material according to any one of claims 1 to 3, which is for absorbing noise of 1000 to 5000 Hz. The back sheet layer is made of a woven fabric or knitted fabric having a shrinkage rate of 20% or more when heated at 150 ° C. for 5 minutes, and the intermediate layer is made of short fibers or long fibers of organic fibers or inorganic fibers. The sound absorbing material according to any one of claims 1 to 4. The sound absorbing material according to any one of claims 1 to 5, wherein the recess is quilted with a sewing thread or ultrasonic waves. The sound absorbing material according to any one of claims 1 to 6, wherein the average thickness of the sound absorbing side sheet layer is 0.2 mm or more and 2.0 mm or less. Any of claims 1 to 7, wherein the fiber constituting the intermediate layer is one or more fibers selected from the group consisting of polyester, nylon, acrylic, vinylon, rayon, aramid, cotton, wool and glass fiber. The sound absorbing material according to the claim. The sound absorbing material according to any one of claims 1 to 8, wherein the back sheet layer is made of a woven fabric or knitted fabric made of acrylic fiber or polyester fiber. The sound absorbing material according to any one of claims 1 to 9, wherein the basis weight is 650 g / m ^{2 or more.} The sound absorbing material according to any one of claims 1 to 10, wherein the sound absorbing side sheet layer is made of synthetic leather, and the surface layer of the synthetic leather is polyvinyl chloride or polyurethane.

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