JP2014016411A - Sound absorbing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sound absorbing material which is light in weight and excellent in sound absorbing performance of a low frequency band.SOLUTION: The sound absorbing material of the present invention is a sound absorbing material formed by laminating an unwoven fabric having a plurality of projections and a porous body, and includes projections formed by the unwoven fabric comprising a plurality of fiber layers. The sound absorbing material includes a plurality of cavities formed by being surrounded by the fiber layers inside the projections. The sound absorbing material exerts an excellent sound absorbing performance against a sound wave of the low frequency band for the reason that it is the sound absorbing material formed by laminating the unwoven fabric and the porous body in this order. Since no fibers exist substantially in the cavities of the unwoven fabric which constitutes the sound absorbing material of the present invention, the sound absorbing material of the present invention is light in weight as compared to the sound absorbing material formed only by the porous body such as, for example, felt which has the same external dimension.

Description

  The present invention relates to a sound absorbing material.

In general, sound-absorbing materials are used to reduce noise generated inside and outside buildings such as general houses, factories, offices, and hospitals, or to reduce noise generated inside and outside vehicles such as aircraft, ships, railway vehicles, and automobiles. It is used to reduce operating noise generated inside equipment such as industrial robots, processing machines, medical equipment or information equipment equipment (for example, televisions, personal computers, printers, scanners, etc.).

  Conventionally, a porous material such as felt has been used as a sound absorbing material, but the porous material tends to be superior in sound absorbing performance for sound waves in a high frequency band, but sound absorbing performance for sound waves in a lower frequency band. There was a tendency to be inferior.

Therefore, in order to improve the sound absorption characteristics in the low frequency region of the sound absorbing material using the porous body, increasing the basis weight and thickness of the porous body, stacking a plurality of the porous bodies, and the like can be cited as countermeasures. However, it has a problem that the weight is increased.

  As a sound-absorbing material having excellent sound-absorbing performance over a wide band, for example, in Japanese Patent Application Laid-Open No. 2004-232162 (hereinafter referred to as Patent Document 1), an intermediate mat is a lap-shaped upper mat and a medium-density lower mat. A felt sound-absorbing material is disclosed.

Since the felt sound-absorbing material according to Patent Document 1 has the above-described configuration, the sound-absorbing material is superior in sound absorption performance at almost all frequencies from the low frequency range to the high frequency range as compared with the conventional sound absorbing material consisting only of felt. It is disclosed to exert.

JP-A-2004-232162 (Claims, 0004-0005, 0047, etc.)

  However, the invention of Patent Document 1 is an invention that mainly examines the relationship between the change in fiber density and the sound absorption performance of the felt sound-absorbing material. In order to obtain a lightweight sound-absorbing material only by examining the invention of Patent Document 1. Was limited.

Therefore, in order to obtain a sound-absorbing material that is lightweight and has excellent sound-absorbing performance in a low-frequency band, further studies are required.

An object of the present invention is to provide a sound-absorbing material that is lightweight and excellent in sound-absorbing performance in a low-frequency band.

The present invention
[1] A sound absorbing material formed by laminating a nonwoven fabric having a plurality of convex portions and a porous body,
The nonwoven fabric has a convex portion configured by including a plurality of fiber layers, and includes a plurality of voids formed by being surrounded by the fiber layer inside the convex portion,
A sound-absorbing material, wherein the sound-absorbing material is laminated in the order of the nonwoven fabric and the porous body in this order from the sound source side. "
It is.

In the “sound-absorbing material formed by laminating a non-woven fabric having a plurality of convex portions and a porous body”, the present inventors have provided the convex portion composed of a plurality of fiber layers and the convex portions. It is a sound-absorbing material having a plurality of voids formed by being surrounded by the fiber layer inside the portion and “stacked in order of the nonwoven fabric and the porous body in order from the sound source side of the sound-absorbing material” Thus, it has been found that the sound absorbing material exhibits excellent sound absorbing performance with respect to sound waves in a low frequency band.

Although the reason for this is not completely clarified, since the sound wave is repeatedly reflected and attenuated in a plurality of voids formed by being surrounded by the fiber layer inside the convex portion of the nonwoven fabric, the sound absorbing material of the present invention is It is considered that the sound absorption performance is excellent.
Further, since the sound absorbing material has a plurality of convex portions on the sound source side, the sound wave traveling from the sound source side easily comes into contact with the non-woven fabric, and the above-described attenuation occurs efficiently. It is thought that it is excellent in performance.

And, since there are substantially no fibers in the voids of the nonwoven fabric constituting the sound absorbing material of the present invention, compared to a sound absorbing material consisting only of a porous body such as felt having the same outer dimensions, The sound absorbing material of the present invention is light in weight.

It is typical sectional drawing when the sound-absorbing material of the present invention is cut in the thickness direction. It is the typical top view which looked at the nonwoven fabric provided with a some convex part from the principal surface side. It is typical sectional drawing which expanded a part of cross section in line segment A-A 'of the nonwoven fabric provided with the some convex part of FIG. A schematic perspective view of a spinning start part in a spinning device capable of producing a nonwoven fabric having a plurality of convex portions according to the present invention, and capable of spinning by discharging a spinning stock solution and a gas flow in parallel; and (B) A schematic cross-sectional view of a spinning start portion on a plane C. FIG. FIG. 3 is a schematic cross-sectional view of a spinning start portion in the spinning device used in Example 1. It is a cross-sectional photograph of the nonwoven fabric provided with Example 1 with a some convex part. It is typical sectional drawing when the sound-absorbing material prepared in Example 1 is cut in the thickness direction. It is the graph which put together the result which used the sound absorption material prepared in Example 1 and Comparative Example 1-3 for the sound absorption measurement.

  The sound absorbing material of the present invention will be described with reference to FIG. 1 which is a schematic cross-sectional view when the sound absorbing material of the present invention is cut in the thickness direction.

The sound-absorbing material (100) of the present invention is a sound-absorbing material formed by laminating a nonwoven fabric (10, hereinafter referred to as an uneven nonwoven fabric) having a plurality of convex portions and a porous body (11). And it is characterized by laminating | stacking in order of the uneven | corrugated nonwoven fabric (10) and the porous body (11) from the sound source side (W) in the sound-absorbing material (100) of this invention.

Subsequently, about the uneven nonwoven fabric (10), FIG. 2 which is a schematic plan view of the nonwoven fabric having a plurality of convex portions as viewed from the main surface side, and the line segment A- of the nonwoven fabric having the plurality of convex portions in FIG. This will be described with reference to FIG. 3, which is a schematic cross-sectional view in which a part of the cross section at A ′ is enlarged. In addition, in FIG. 3, a part of cross section in line segment AA 'is expanded, and typical sectional drawing of two convex parts (1a, 1b) is shown in figure.

In FIG. 2, the uneven nonwoven fabric (10) has a plurality of convex portions (1) having a substantially quadrangular shape present at equal intervals on the main surface, and a non-existing portion (2, hereinafter, convex portions present in a lattice shape). An embodiment provided with a recess portion) is illustrated. Moreover, the line segment which crosses the uneven | corrugated nonwoven fabric (10) through the vertex of two or more convex parts (1) at the time of seeing the uneven nonwoven fabric (10) from the main surface side is made into line segment AA '. It is shown.

And as shown in FIG. 3, the uneven | corrugated nonwoven fabric (10) is provided with the convex part (for example, 1a, 1b) comprised by providing multiple fiber layers (3), and the said convex part ( For example, a plurality of voids (4) formed by being surrounded by the fiber layer (3) are provided inside 1a, 1b). In addition, the surface (upper surface on the paper surface in FIG. 3) in which the convex portions (1, 1a, 1b) mainly exist in the uneven nonwoven fabric (10) is the “main surface”, and the surface in the uneven nonwoven fabric (10). The surface opposite to the main surface (the surface in the downward direction on the paper surface in FIG. 3) is referred to as “the other main surface”.

In FIG. 3, the thickness of the uneven nonwoven fabric (10) is represented by a line segment t1, the height of a convex portion (for example, 1b) is represented by a line segment t2, and the thickness of the concave portion (2) is represented by a line segment t3. .
The thickness (t1) of the concavo-convex nonwoven fabric (10) is a convex portion (e.g., analyzed by an electron micrograph of a cross section obtained by cutting the concavo-convex nonwoven fabric (10) in the thickness direction along the line AA ′ (for example, This is the shortest distance between the vertex of 1b) and the other main surface. Further, the thickness (t3) of the concave portion (2) is the same as the main surface in the concave portion (2) adjacent to the convex portion (for example, 1b) used when calculating the thickness (t1). The shortest distance from one main surface. Furthermore, the height (t2) of the convex portion (for example, 1b) means a length obtained by subtracting the thickness (t3) of the concave portion (2) from the thickness (t1) of the concave-convex nonwoven fabric (10).

In the present invention, an electron micrograph of a cross section of the uneven nonwoven fabric (10) photographed as described above is hereinafter referred to as a cross-sectional photograph.

Further, the “fiber layer” (3) in the present invention refers to a fiber layer applicable to the method for determining the fiber layer (3) described below.
(Judgment method of fiber layer (3))
1. The fibers constituting the uneven nonwoven fabric (10) by analyzing electron micrographs and cross-sectional photographs of the main surface of the uneven nonwoven fabric (10) and calculating the arithmetic average value of the fiber diameters of 50 fibers randomly selected The average fiber diameter is calculated. The fiber diameter refers to the diameter of a circle having the same area as the cross-sectional area of the fiber.
2. In the cross-sectional photograph, a straight line (shown as B in FIG. 3 and hereinafter referred to as a straight line B) connecting the shortest distance between the apex of the convex portion (for example, 1b) and the other main surface, and each fiber layer having an intersection point Measure the thickness.
3. When the thickness of the fiber layer having the intersection with the straight line B is within the range of 3 to 20 times the average fiber diameter of the fibers constituting the uneven nonwoven fabric (10), the “fiber layer” (3) according to the present invention. It is judged that.

The fiber layer (3) is branched even in a mode in which the fiber layers (3) adjacent to each other in the vertical direction on the paper surface are in contact with each other or integrated like the convex portion (1b) illustrated in FIG. The aspect provided with the made fiber layer (3) may be sufficient.

The present inventors have found that the sound absorbing material (100) of the present invention having the above-described configuration exhibits excellent sound absorbing performance for sound waves in a low frequency band.
The reason for this is not completely clear, but in the plurality of voids (4) formed by being surrounded by the fiber layer (3) inside the convex portion (for example, 1a, 1b) of the uneven nonwoven fabric (10). Since the sound waves are repeatedly reflected and attenuated, the sound absorbing material (100) of the present invention is considered to be excellent in sound absorbing performance.
Furthermore, by providing a plurality of convex portions (for example, 1a, 1b) on the sound source side (W) of the sound absorbing material (100), the sound waves traveling from the sound source side (W) come into contact with the uneven nonwoven fabric (10). Since the above-described attenuation occurs efficiently, the sound absorbing material (100) of the present invention is considered to be excellent in sound absorbing performance.

And since the fiber is not substantially present in the void (4) of the uneven nonwoven fabric (10) constituting the sound absorbing material (100) of the present invention, a porous body such as felt having the same outer dimensions. Compared to the sound absorbing material consisting only of, the sound absorbing material (100) of the present invention is light in weight.

Next, details of the present invention will be described.

  Various characteristics, such as thickness (t1), fabric weight, and air permeability, of the concavo-convex nonwoven fabric (10) are not particularly limited, and are appropriately adjusted so as to obtain a sound-absorbing material (100) having excellent sound-absorbing performance. .

The thickness (t1) of the uneven nonwoven fabric (10) is preferably 50 μm to 10 mm, more preferably 200 μm to 7 mm, and most preferably 500 μm to 5 mm. Also, the basis weight of the uneven nonwoven fabric (10) is, for ^example, is preferably from ^{1g / m 2 ~100g / m 2} , more preferably from ^{4g / m 2 ~70g / m 2} , 10g / m 2 ~50g Most preferred is / m ² . In the present invention, the basis weight refers to the mass per 1 m ^{2 on} the widest principal surface of the measurement object.

Further, breathable uneven nonwoven fabric (10) ^is preferably from ^{0.01cm 3 / cm 2 / s~300cm 3} / cm 2 / s, 1cm 3 / cm 2 / s~100cm 3 / cm 2 / s and more preferably ^at, it is most preferable ^{6cm 3 / cm 2 / s~50cm 3} / cm 2 / s. In particular, when the air permeability of the uneven nonwoven fabric (10) is lower than the air permeability of the porous body (11) described later, the sound absorbing material (100) having further excellent sound absorbing performance tends to be obtained, which is preferable. .

  The reason for this is not completely clear, but a layer with low breathability is more likely to collide with sound waves than a layer with high breathability, and a layer with low breathability is likely to move due to collision with sound waves. The motion of the layer with low air permeability is transmitted to the laminated porous body, and the porous body resonates at a specific frequency as a spring, so that the sound absorbing material (100) exhibits a sound absorbing effect on the specific frequency and the sound absorbing material has a low frequency. It is considered that excellent sound absorption performance can be exhibited with respect to sound waves in a band.

In addition, in this invention, air permeability means the value measured by the method prescribed | regulated to JISL 1913: 2000 (general nonwoven fabric test method) 6.8.1 (fragile type method).

  When the concave / convex nonwoven fabric (10) is viewed from the main surface side, for example, the number of convex portions (1), the shape and arrangement of the convex portions (1), the convex portion (1) occupies one area and the concave / convex nonwoven fabric (10). Aspects such as the area ratio of the convex portion (1) are not particularly limited, and are appropriately adjusted so as to obtain a sound absorbing material (100) having excellent sound absorbing performance.

The larger the number of convex portions (1), the more preferable the uneven nonwoven fabric (10) has a larger surface area on the main surface side, and further there is a tendency to obtain a sound absorbing material (100) excellent in sound absorbing performance. Therefore, the number of convex portions (1) provided on the main surface of the uneven nonwoven fabric (10) is preferably 1600 pieces / m ² or more, and most preferably 40000 pieces / m ² or more. The upper limit of the number of convex portions (1) is adjusted as appropriate so that the rigidity of the concave-convex nonwoven fabric (10) becomes weak and breakage easily occurs, and the sound absorbing performance of the sound absorbing material (100) can be prevented from deteriorating. , preferably at 4000000 cells / ^{m 2} or less, more preferably 640000 or / ^{m 2} or less.

  The shape of the convex part (1) when the uneven nonwoven fabric (10) is viewed from the main surface side is, for example, a polygonal shape such as a round shape or a hexagonal shape, a linear shape, a numeric shape, an alphabet shape, an indefinite shape, or the like. it can. Further, the arrangement of the convex portions (1) may be an aspect in which the intervals between the convex parts (1) are uniform (for example, an aspect in which they are arranged in a staggered manner), or a convex part (1). It can be set as the aspect which exists so that the space | intervals may become non-uniform | heterogenous.

Further, when viewed uneven nonwoven fabric (10) from the main surface side, convex portion (1) one area, for ^example, is preferably from ^{0.1mm 2 ~548mm 2, 0.8mm 2 ~13.5mm} 2 It is more preferable that

And when the uneven | corrugated nonwoven fabric (10) is seen from the main surface side, the surface area of the uneven | corrugated nonwoven fabric (10) becomes large, so that the area ratio of the convex part (1) to the uneven | corrugated nonwoven fabric (10) is large, There exists a tendency which can obtain the sound-absorbing material (100) excellent in sound-absorbing performance, and it is preferable. Therefore, the area ratio of the convex portion (1) in the uneven nonwoven fabric (10) is preferably 30% or more, more preferably 40% or more, more preferably 50% or more, and 70%. More preferably, it is more preferably 80% or more. In addition, since the uneven | corrugated nonwoven fabric (10) becomes flat form when the area ratio of the convex part (1) to an uneven | corrugated nonwoven fabric (10) is 100%, it becomes impossible to improve the surface area of a main surface side, Therefore an uneven | corrugated nonwoven fabric (10) The area ratio of the convex portion (1) in the area is less than 100%.

The height (t2) of the convex part (1) in the concavo-convex nonwoven fabric (10) is not particularly limited, and is adjusted as appropriate so that a sound-absorbing material (100) excellent in sound-absorbing performance can be obtained. The higher the height (t2) of the convex portion (1) in the uneven nonwoven fabric (10), the larger the surface area on the main surface side of the uneven nonwoven fabric (10), and further obtaining the sound absorbing material (100) having excellent sound absorbing performance. This tends to be possible and is preferable. Therefore, the height (t2) of the uneven nonwoven fabric (10) is, for example, preferably 25 μm or more, more preferably 250 μm or more, and most preferably 300 μm or more. Moreover, although the upper limit of the height (t2) of an uneven | corrugated nonwoven fabric (10) is not limited and it adjusts suitably, it is preferable that it is 9 mm or less, it is more preferable that it is 4.5 mm or less, and 1.4 mm or less. Most preferably.

Convex portions (for example, 1a, 1b) formed by a plurality of voids (4) formed by being surrounded by the fiber layer (3) in the number of convex portions (1) in the uneven nonwoven fabric (10) The greater the ratio of the number, the more the uneven nonwoven fabric (10), for example, when the surface area on the main surface side is the same, the weight of the basis weight can be reduced, and when the basis weight is the same, the surface area on the main surface side is reduced. Increase can be achieved. Therefore, the ratio is greater than 0%, preferably 90% or more, more preferably 95% or more, and most preferably 100%.

In addition, when uneven | corrugated nonwoven fabric (10) is comprised only by the fiber layer (3) which is not provided with fiber orientation but is provided with irregular fiber orientation, when force acts with respect to uneven | corrugated nonwoven fabric (10). Even if it exists, it can prevent that a fracture | rupture generate | occur | produces in an uneven | corrugated nonwoven fabric (10), and can prevent that the sound-absorbing performance of a sound-absorbing material (100) falls. Further, even when the uneven nonwoven fabric (10) is subjected to pleating, winding or laminating, it is possible to prevent the sound absorbing performance of the prepared sound absorbing material from unintentionally decreasing due to the occurrence of breakage.

In the uneven nonwoven fabric (10), the number of the fiber layers (3) constituting one convex portion (for example, 1a, 1b) is not particularly limited, and further, a sound absorbing material ( 100) is appropriately adjusted.
The larger the number of fiber layers (3) constituting one convex part (for example, 1a, 1b), the better the shape stability of the convex part (for example, 1a, 1b), and the uneven nonwoven fabric (10). It is possible to prevent the sound absorbing performance of the sound absorbing material (100) from being deteriorated by preventing breakage. Therefore, the number of the fiber layers (3) present inside each convex portion (for example, 1a, 1b) is preferably 5 layers or more, more preferably 7 layers or more, and 10 layers or more. Most preferably.

In addition, the number of the fiber layers (3) constituting each convex portion (for example, 1a, 1b) is a fiber having an intersection with the straight line B in the above-described (determination method of the fiber layer (3)). Obtained by measuring the number of layers (3).

  The shape and number of the gaps (4) formed by being surrounded by the fiber layer (3), and the size of the gaps (4) per one are not particularly limited, and the sound absorbing material is further excellent in sound absorbing performance. Adjust appropriately so that (100) can be obtained.

The shape of the gap (4) in the cross-sectional photograph can be, for example, a crescent shape, an oval shape, a circular shape, a polygonal shape, an indefinite shape, or the like. Further, the number of voids (4) existing inside one convex portion (for example, 1a, 1b) is not limited, and is adjusted as appropriate so that a plurality of voids (4) exist. The number of voids is preferably 6 or more and more preferably 8 or more because the surface area on the main surface side of the uneven nonwoven fabric (10) tends to be increased by increasing the height of the convex portion (1). And more preferably 11 or more. The number of voids (4) can be obtained by analyzing a cross-sectional photograph.

  The size of the gap (4) per one is preferably adjusted as appropriate. However, the larger the size per gap (4) per convex portion (for example, 1a, 1b), the larger the convex portion. There is a tendency that the surface area on the main surface side of the uneven nonwoven fabric (10) can be increased by increasing the height (t2) of (1).

  In the present invention, the size per gap (4) per convex part (for example, 1a, 1b) occupies the area per convex part (for example, 1a, 1b) in the cross-sectional photograph, Evaluation is based on the percentage of the area per void (4) (hereinafter referred to as the percentage of void area).

  The percentage of the void area is preferably 5% or more and less than 100%, and more preferably 6% or more and less than 100%.

In addition, the area per one convex part (for example, 1a, 1b) is the range (for example, the range of 1a or 1b in FIG. 3) in which the thickness is larger than the thickness of the concave part (2) in the cross-sectional photograph. ) By calculating the area in the cross-sectional photograph.

  Examples of the fiber component constituting the uneven nonwoven fabric (10) include, for example, polyolefin resins (polyethylene resin, polypropylene resin, polymethylpentene, polyolefin resin having a structure in which a part of hydrocarbon is substituted with a halogen such as cyano group or fluorine or chlorine). , Styrene resin, polyvinyl alcohol resin, polyether resin (polyether ether ketone, polyacetal, phenol resin, melamine resin, urea resin, epoxy resin, modified polyphenylene ether, aromatic polyether ketone, etc.), Polyester resin (polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polycarbonate, polyarylate, wholly aromatic polymer Ester resins, unsaturated polyester resins, etc.), polyimide resins, polyamideimide resins, polyamide resins (for example, aromatic polyamide resins, aromatic polyetheramide resins, nylon resins, etc.), resins having a nitrile group (for example, Polyacrylonitrile, etc.), urethane resin, epoxy resin, polysulfone resin (polysulfone, polyethersulfone, etc.), fluorine resin (polytetrafluoroethylene, polyvinylidene fluoride, etc.), cellulose resin, polybenzimidazole resin, acrylic Such as polyacrylonitrile resin copolymerized with acrylic acid ester or methacrylic acid ester, modacrylic resin copolymerized with acrylonitrile and vinyl chloride or vinylidene chloride, etc. Polymer, or it may be used a metal alkoxide (silicon, aluminum, titanium, zirconium, boron, tin, methoxide such as zinc, ethoxide, propoxide, butoxide, etc.), inorganic polymer is formed of a sol or a gel compound polymerized.

These fiber components may be either linear polymers or branched polymers, and may be block copolymers or random copolymers, and may have any three-dimensional structure or crystallinity. There is no particular limitation.
Furthermore, what mixed these fiber components may be used, and it does not specifically limit.

Moreover, the fiber which comprises an uneven | corrugated nonwoven fabric (10) may be comprised from a single type or multiple types of fiber component. Examples of fibers comprising a plurality of types of resin components include composite fibers generally called composite fibers, such as core-sheath type, sea-island type, side-by-side type, and orange type.

In addition to the above-described fiber component, for example, inorganic particles, pigments, flame retardants, insecticides, fragrances, deodorizers, catalysts, surfactants, medicinal components, and the like are added as components constituting the uneven nonwoven fabric (10). be able to.

The fibers constituting the uneven nonwoven fabric (10) tend to be able to obtain a sound-absorbing material (100) having better sound-absorbing performance as the average fiber diameter is thinner. Therefore, the average fiber diameter of the fibers constituting the uneven nonwoven fabric (10) is, for example, preferably 100 nm to 30 μm, more preferably 500 nm to 10 μm, and most preferably 1 μm to 3 μm. The “average fiber diameter” as used in the present invention is measured and calculated using the method described in the above (Fiber layer (3) determination method).

  The CV value calculated from the average fiber diameter of the fibers constituting the concavo-convex nonwoven fabric (10) (hereinafter referred to as the CV value of the fiber diameter) is appropriately selected so that a sound absorbing material (100) having excellent sound absorbing performance can be obtained. Although it can be adjusted and is not limited, it is preferably 10% to 140%, preferably 15% to 80%, and more preferably 20% to 60%.

The fiber diameter CV value referred to in the present invention is calculated by the following method.
1. An electron micrograph of the nonwoven fabric is analyzed, and an arithmetic average value of fiber diameters of 50 fibers selected at random is calculated to calculate an average fiber diameter (Xav).
2. A standard deviation value (SD) is calculated on the basis of the measured values of the fiber diameters of 50 fibers, which are measurement targets for calculating the average fiber diameter (Xav).
3. The fiber diameter CV value (coefficient of variation) is calculated from the following equation.
CV value of fiber diameter (%) = (SD / Xav) × 100

Hereinafter, the manufacturing method of an uneven | corrugated nonwoven fabric (10) is demonstrated.

  The method for producing the concavo-convex nonwoven fabric (10) is not particularly limited. For example, a melt blow method, a spun bond method, an electrostatic spinning method, a method in which a spinning solution and a gas flow are discharged in parallel and spun (for example, Using a direct spinning method such as those disclosed in JP 2009-287138 A, JP 2011-111686 A, etc.), the spinning stock solution is discharged from the spinning stock solution discharge port, fiberized, and fiberized. By collecting the spinning dope in the collection body, the uneven nonwoven fabric (10) can be formed on the collection body.

When the concavo-convex nonwoven fabric (10) is prepared using only the direct spinning method, the concavo-convex nonwoven fabric (10) is constituted only by the fiber layer (3) having no fiber orientation and having an irregular fiber orientation. Thus, the nonwoven fabric (10) of the invention can be made difficult to break, and the sound absorption performance due to the occurrence of breakage can be prevented from being lowered. Furthermore, since the steps from fiberization of the spinning dope to production of the rugged nonwoven fabric (10) can be performed using the same spinning dope under the same spinning conditions, the integration of the fibers can be made stronger. Thus, the non-woven fabric (10) of the invention can be made to be a mode that is not easily broken, and the sound absorbing performance due to the occurrence of the breaking can be prevented from being lowered.

When producing a concavo-convex nonwoven fabric (10) using the direct spinning method, for example, a discharge amount of a spinning stock solution such as a melted fiber component or a fiber component solution dissolved in a solvent, a liquid discharge port of the spinning stock solution and a trap. When a force such as a gas flow is applied to the collection distance (collection distance) and the spinning dope, the gas flow rate, angle, temperature, spinning conditions, and fiber collection conditions are adjusted as appropriate.

  The type of the collector is not particularly limited. For example, a fabric such as a woven fabric, a knitted fabric or a non-woven fabric, a porous film, a foamed sheet, a net having a through hole from one main surface to the other main surface (for example, a knot) A material having a concave portion such as a gap or a groove or a through hole on the main surface, such as a net or a knotless net, can be used.

  By collecting the spinning stock solution that has been fiberized into the collector made of the material as described above, the fiberized spinning solution enters the recessed portion or the through hole present on the main surface of the collector, and the uneven nonwoven fabric ( The convex part (1) in 10) is formed. Therefore, the shape, distribution and size of the depressed portion and the through hole provided in the collector, the depth of the depressed portion, the depth of the through hole, and the like are appropriately adjusted so that the uneven nonwoven fabric (10) can be prepared.

The shape of the recessed portion or the through hole when the collector is viewed from the main surface side is, for example, a polygonal shape such as a round shape or a hexagonal shape, a linear shape, a numeric shape, an alphabet shape, an indefinite shape, or the like. Can do.

  Moreover, since it is easy to form the convex part (for example, 1a, 1b) in which the space | gap (4) formed surrounded by the fiber layer (3) exists, a net etc. are used as a collection body. It is preferable to use a collector having a through hole.

  The mode of the net that can be used as the collector is adjusted as appropriate, but if the size of the through-hole provided in the net is too small, there are a plurality of voids (4) that are surrounded by the fiber layer (3). It is preferable to use a net having a mesh number of 50 mesh or less, more preferably using a net having a mesh of 45 mesh or less. It is more preferable to use a net of 40 mesh or less, more preferable to use a net of 30 mesh or less, more preferable to use a net of 20 mesh or less, and most preferable to use a net of 10 mesh or less. preferable. Moreover, even if the size of the through-hole provided in the net is too large, convex portions (for example, 1a and 1b) formed by a plurality of voids (4) formed surrounded by the fiber layer (3) are present. It is preferable to use a net having a mesh number larger than 1 mesh because it tends to be difficult to form.

In addition, the arrangement of the through holes in the collector including the through holes is an aspect in which the intervals between the through holes are uniform (for example, an aspect in which the through holes are arranged in a staggered manner), or between the through holes. The thing of the aspect which exists so that a space | interval may become nonuniform can be used.

  By appropriately adjusting the distance (collection distance) between the liquid discharge port of the spinning dope and the collection portion, the height (t2) of the convex portion (for example, 1a, 1b) of the uneven fabric (10) obtained, The number of fiber layers (3) constituting the portion (for example, 1a, 1b), the thickness of the fiber layer (3), the shape, number and size of the gap (4), and the convex portion (for example, 1a, 1b) ) It is possible to adjust the size of the gap (4) occupied per unit, and it is possible to obtain the sound absorbing material (100) having excellent sound absorbing performance.

The distance between the liquid discharge port of the spinning dope and the collection body is preferably adjusted as appropriate in relation to other spinning conditions. However, if the distance is too close or too far, a convex portion (for example, 1a, 1b ) There is a tendency that the fiber layer (3) and the void (4) are hardly formed inside. Therefore, the distance between the spinning solution outlet and the collector is preferably 1 cm to 100 cm, more preferably 2 cm to 30 cm, and most preferably 2.5 cm to 7 cm.

As a method for producing the uneven nonwoven fabric (10), in particular, a method in which a spinning solution and a gas flow are spun by discharging in parallel (for example, methods disclosed in JP2009-287138A, JP2011-111686A, etc.) ), For example, compared to other direct spinning methods such as the melt blow method, the generation of shots and beads (particle-shaped resin) can be prevented, and fibers with a small fiber diameter and a uniform fiber diameter can be spun. Furthermore, a sound absorbing material (100) having excellent sound absorbing performance can be obtained, which is preferable.

  A method for producing the uneven nonwoven fabric (10) will be described with reference to FIG. 4 in the case of using a spinning method in which a spinning solution and a gas flow are discharged in parallel.

FIG. 4 illustrates an embodiment of a spinning device that can produce a concavo-convex nonwoven fabric (10) and can perform a spinning method by discharging a spinning raw solution and a gas flow in parallel. FIG. 2 is a schematic perspective view of a spinning start portion, and (b) a schematic cross-sectional view of a spinning start portion on a plane C.

  The above-described spinning device (20, hereinafter referred to as a spinning device) capable of performing the spinning method by discharging the spinning solution and the gas flow in parallel has one liquid discharge port (El) that can discharge the spinning solution. Spinning having a spinning start portion that is located upstream of any one of the liquid discharge ports (El) and has one gas discharge port (Eg) that can discharge gas and that satisfies the following conditions: Device (20).

(1) It has a liquid discharge part (Nl) provided with a liquid columnar hollow part (HI) with the liquid discharge port (El) as an end.
(2) It has a gas discharge part (Ng) provided with a columnar hollow part for gas (Hg) whose end is a gas discharge port (Eg).
(3) The liquid virtual columnar part (HvI) obtained by extending the liquid columnar hollow part (HI) and the gas virtual columnar part (Hvg) obtained by extending the gas columnar hollow part (Hg) are close to each other.
(4) The liquid discharge direction central axis (AI) of the liquid columnar hollow part (HI) and the gas discharge direction central axis (Ag) of the gas columnar hollow part (Hg) are parallel.
(5) of the spinning start section provided in the spinning device (20) shown in FIG. 3 (b) when cut by a plane (plane C) perpendicular to the central axis of the columnar hollow portion (Hg) for gas. In the schematic sectional view, only _one straight line (L ₁ ) having the shortest distance between the outer periphery of the cut surface of the gas columnar hollow portion (Hg) and the outer periphery of the cut surface of the liquid columnar hollow portion (HI) is drawn. Is in a state where it can.

  When the spinning solution is supplied to the liquid discharge part (Nl) and the gas is supplied to the gas discharge part (Ng), the spinning raw solution passes through the liquid columnar hollow part (HI) and from the liquid discharge port (EI) to the liquid columnar hollow part. At the same time as being discharged in the axial direction of (HI), the gas passes through the gas columnar hollow portion (Hg) and is discharged from the gas discharge port (Eg) in the axial direction of the gas columnar hollow portion (Hg).

  The discharged gas and the spinning dope are close to each other, the gas discharge direction and the spinning dope discharging direction are in parallel relation, and on the plane C, the discharged gas and the discharged spinning dope are The closest point is one point, that is, the spinning dope is subjected to shearing action by gas and accompanying airflow in a single straight line, so it flies in the axial direction of the liquid columnar hollow part (HI) while reducing the diameter, and fiberized To do. The liquid virtual columnar portion (HvI), which is an extension of the liquid columnar hollow portion (HI), is a flight path immediately after the discharge of the spinning raw liquid discharged from the liquid discharge port (EI), and the gas columnar hollow portion (Hg). The gas imaginary columnar portion (Hvg) extended from is an ejection path immediately after ejection of the gas ejected from the gas ejection port (Eg).

Then, the fiberized spinning dope is collected by a collector (not shown) present on the axial direction side of the liquid columnar hollow (HI), whereby an uneven nonwoven fabric (10) can be produced on the collector. . At this time, by providing a suction device on the back surface side of the collecting body and / or the side surface peripheral portion of the collecting body when viewed from the spinning start side of the spinning device (20), the fiberized spinning dope is collected. Can assist in being collected on top.

By using the spinning device (20) provided with such a spinning start portion, it is possible to uniformly apply a shearing action to the spinning dope, prevent the generation of shots and beads, reduce the fiber diameter, and align the fiber diameter. Since the spun fiber can be spun, a sound absorbing material (100) having further excellent sound absorbing performance can be obtained.

  The shape of the liquid discharge port (EI) is not particularly limited, and can be, for example, a circular shape, an oval shape, an elliptical shape, or a polygonal shape (for example, a triangle, a quadrangle, or a hexagon). A circular shape is preferred so that the shearing action of the gas and the accompanying airflow is received in one straight line, and shots and beads are less likely to occur.

Then, without limitation particularly also the size of the liquid discharge port ^(EI), is preferably from 0.01mm ² ~0.28mm ^2, and more preferably 0.02mm ² ~0.07mm 2. If it is smaller than 0.01 mm ² , it tends to be difficult to discharge a spinning solution having a high viscosity, and if it exceeds 0.28 mm ² , it becomes difficult to apply a shearing action to the entire discharged spinning solution. This is because shots and beads tend to occur.

  4 (a) and 4 (b) show a cylindrical liquid discharge portion (Nl), it is also possible to use an acute angle nozzle whose tip is cut with an inclination. This acute-angle nozzle is effective when the viscosity of the spinning dope is high. When such an acute angle nozzle is used, if the sharp side is the gas discharge part (Ng) side, it is easy to be subjected to the shearing action of the gas and the accompanying air flow, and can be stably fiberized.

  The shape of the gas discharge port (Eg) is not particularly limited, and may be, for example, a circular shape, an oval shape, a circular shape, a polygonal shape (for example, a triangle, a quadrangle, a hexagon), or a slit-like opening. it can.

And the magnitude | size of a gas discharge port (Eg) is not specifically limited, It adjusts suitably. Note that the size of the gas discharge port (Eg) is preferably the same as or larger than the size of the liquid discharge port (EI). This is because the shearing action of the heated gas and the accompanying airflow tends to work.

  Since the gas discharge part (Ng) is arranged so that the gas discharge port (Eg) is upstream (supply side of the spinning stock solution) from the liquid discharge port (EI), spinning is performed around the liquid discharge port (EI). The stock solution can be prevented from rolling up.

Therefore, it is possible to perform spinning for a long time without soiling the liquid discharge port (EI). The distance between the gas discharge port (Eg) and the liquid discharge port (EI) is not particularly limited, but is preferably 10 mm or less, and more preferably 5 mm or less. This is because if it exceeds 10 mm, the shearing force of the gas and the accompanying airflow with respect to the spinning dope becomes insufficient, and it tends to be difficult to form fibers. The lower limit of the difference in distance between the gas discharge port (Eg) and the liquid discharge port (EI) is not particularly limited, and it is sufficient that the gas discharge port (Eg) and the liquid discharge port (EI) do not coincide with each other.

  The distance between the liquid virtual columnar part (HvI) and the gas virtual columnar part (Hvg) is preferably 2 mm or less, and more preferably 1 mm or less. This is because if it exceeds 2 mm, the shearing force of the gas and the accompanying airflow hardly acts, and it tends to be difficult to be fiberized.

  Furthermore, the liquid discharge direction central axis (AI) of the liquid columnar hollow part (HI) and the gas discharge direction central axis (Ag) of the gas columnar hollow part (Hg) are parallel to the discharged spinning solution. Since the gas and the accompanying airflow can act on one straight line, the fiber can be stably spun. If these central axes are at the crossing or twisting positions, the shearing force due to the gas and the accompanying airflow does not act or even if it acts, the fibers cannot be stably spun.

The term “parallel” means that the liquid discharge direction central axis (AI) of the liquid columnar hollow portion (HI) and the gas discharge direction central axis (Ag) of the gas columnar hollow portion (Hg) are on the same plane. It can be located and is parallel. Further, the “ejection direction central axis” is a straight line formed by connecting the center of the ejection part and the center of the cross section of the virtual columnar part.

In the spinning start part in the spinning device (20), when cut in a plane (plane C) perpendicular to the central axis of the gas columnar hollow part (Hg), as shown in FIG. Only _one straight line (L ₁ ) having the shortest distance between the outer periphery of the cut surface of the gas columnar hollow portion (Hg) and the outer periphery of the cut surface of the liquid columnar hollow portion (HI) can be drawn.

The gas discharged from the gas columnar hollow part (Hg) and the accompanying airflow act in a straight line on the spinning dope discharged from the liquid columnar hollow part (HI), and the shearing action Can be stably spun without producing shots or beads.

When the spinning device (20) includes a suction device, the volume of the gas sucked by the suction device is the volume of the gas discharged from the gas discharge port (Eg), or the form of the uneven nonwoven fabric (10) to be manufactured. It is preferable to adjust appropriately.

  The viscosity and temperature of the spinning dope used for spinning, the type of solvent when the spinning dope contains a solvent, the ratio of the solvent in the spinning dope, the type and temperature of gas, and the temperature in the atmosphere near the spinning start part. Humidity etc. are adjusted appropriately.

  The discharge mass of the spinning dope discharged from the liquid discharge port (EI) is preferably adjusted according to other spinning conditions in the spinning device (20), but the uneven nonwoven fabric ( Since the convex portion (1) in 10) tends not to be formed, it is preferably 0.021 g / hour to 50 g / hour, and 0.1 g / hour to 25 g per one liquid discharge port (El). / Hour is preferred, and most preferred is 1 g / hour to 3 g / hour.

The discharge volume of the gas discharged from the gas discharge port (Eg) is preferably adjusted as appropriate according to other spinning conditions in the spinning device (20). all the ejection volume of the gas that tends to hardly convex portion (1) is formed in (10) ^is preferably ^{100Nm 3 / hour / m~1000Nm 3 /} hour / m, 200Nm 3 / hour / m Most preferred is ˜900 Nm ³ / hour / m.

  Furthermore, in the spinning device (20), an electric field may be applied to the spinning dope during spinning. As a method for applying an electric field to the spinning dope, a method of forming a potential difference between the spinning dope and the collector can be employed.

  In order to form a potential difference between the spinning dope and the collector, for example, a power source such as a DC high-voltage generator or a Van de Graf generator is brought into contact with the collector or the spinning dope, so that the collector or spinning dope Either applying a voltage to one side and grounding the one that is not in contact with the power source, or bringing the power source into contact with both the spinning stock solution and the collector, and generating a voltage difference between the spinning stock solution and the collector. The method of applying can be mentioned. The applied polarity may be positive or negative.

Alternatively, instead of forming a potential difference between the spinning dope and the collecting body, a counter electrode is arranged on the back side of the collecting body when viewed from the spinning start side of the spinning device (20), and the spinning dope and the counter electrode are arranged. A potential difference can be formed between the two.

  The potential difference formed between the spinning solution and the collector or the counter electrode is preferably adjusted as appropriate depending on the type of spinning solution, the above-described spinning conditions, and the like, but is not particularly limited, but 0.05 kV / cm to It is preferably 20 kV / cm. When the potential difference exceeds 20 kV / cm, spinning by the same voltage as that of the electrostatic spinning method is dominant rather than spinning by the shearing action of the gas, but the texture of the nonwoven fabric prepared by receiving the action of the gas tends to deteriorate. There is.

The uneven nonwoven fabric (10) formed on the collector as described above is peeled off from the collector, or the uneven nonwoven fabric (10) formed on the collector as described above is peeled off from the collector. The sound-absorbing material (100) may be prepared by laminating the entire collection body with the porous body (11) described later, but the uneven nonwoven fabric (10) is subjected to a binder treatment or a heat treatment. ) And / or when the solvent remains in the uneven nonwoven fabric (10), the uneven nonwoven fabric (10) is subjected to heat treatment. After removing the remaining solvent from the inside, the sound absorbing material (100) may be prepared by laminating with a porous body (11) described later. Or you may use an uneven | corrugated nonwoven fabric (10) for the addition treatment process of additives, such as an inorganic particle, a pigment | dye, a flame retardant, an insecticide, a fragrance | flavor, a deodorizing agent, a catalyst, surfactant, a medicinal component, etc., for example.

The porous body (11) in the present invention refers to, for example, a single body or a plurality of laminated materials such as a nonwoven fabric, a fabric such as a woven fabric or a knitted fabric, a porous film or a foam. In addition, the raw material which comprises a porous body (11) can be prepared using the organic polymer mentioned above as a fiber component which comprises an uneven | corrugated nonwoven fabric (10), or an inorganic polymer.

  Various characteristics such as thickness, basis weight, and air permeability of the porous body (11) are not particularly limited, and are appropriately adjusted so as to obtain a sound absorbing material (100) excellent in sound absorbing performance.

  The thickness of the porous body (11) is preferably 1 mm to 100 mm, more preferably 2 mm to 50 mm, more preferably 3 mm to 25 mm, and most preferably 4 mm to 7 mm. The thickness of the porous body (11) refers to a value obtained by measuring the shortest distance between both main surfaces of the porous body (11) with a caliper.

Also, the basis weight of the porous body (11), for ^example, is preferably from ^{20g / m 2 ~5000g / m 2} , more preferably from ^{40g / m 2 ~2500g / m 2} , 60g / m 2 ~1250g more preferably from / ^{m 2,} and most preferably from ^{80g / m 2 ~350g / m 2} .

The air permeability of the porous body (11) is preferably 1 cm ³ / cm ² / s to 1000 cm ³ / cm ² / s, and is preferably 10 cm ³ / cm ² / s to 100 cm ³ / cm ² / s. more ^preferably, it is most preferable ^{25cm 3 / cm 2 / s~75cm 3} / cm 2 / s.

  When a fabric is used as the material constituting the porous body (11), the fineness of the fibers constituting the fabric is not particularly limited, but the sound absorbing material (100) having excellent sound absorbing performance can be obtained. The fineness is preferably 0.01 to 100 dtex, and more preferably 0.1 to 30 dtex. Also, the fiber length is not particularly limited, but it is preferably 1 mm or more, more preferably 3 to 100 mm, and depending on the fiber production method, it may be a continuous fiber. In addition, the fabric which contains two or more types of fibers which differ in the fineness and / or fiber length may be sufficient.

  Moreover, the fiber which comprises the said fabric may be a composite fiber which consists of two or more types of organic polymer and / or inorganic polymer. If the organic polymer component constituting the surface of the composite fiber has a low melting point, it can be fused with the low melting point organic polymer component while maintaining the fiber form. Examples of the cross-sectional form of the composite fiber include a core-sheath type (including an eccentric type), a sea-island type, a side-by-side type, an orange type, and a multilayer laminated type.

The fibers constituting the fabric include, for example, a dry spinning method, a wet spinning method, a direct spinning method, a method of extracting a fiber having a small fiber diameter by removing one or more kinds of resin components from a composite fiber, and beating the fiber. It can be obtained by a known method such as a method of obtaining divided fibers.

Woven fabrics and knitted fabrics can be prepared by weaving or knitting the fibers prepared as described above.

  In addition, the nonwoven fabric is prepared by applying the fiber obtained by the above-described method to, for example, a dry method, a wet method, and preparing a fiber web, and bonding the fibers constituting the fiber web by a method described later. it can. In addition, you may prepare a nonwoven fabric not only using only one layer of fiber webs but manufacturing a nonwoven fabric using the laminated fiber web which laminated | stacked two or more fiber webs with the same or different fiber mixing. Furthermore, the fiber web may be a parallel web, a cross web, a random web, or a criss cross web obtained by laminating a parallel web and a cross web, and is not particularly limited.

  Examples of a method for producing a nonwoven fabric by bonding fibers constituting a fiber web include, for example, a method in which fibers are entangled with each other by a needle or a water stream, and a fiber having a low melting point organic polymer component on its surface (for example, a composite fiber). Examples of the method include a method in which fibers are bonded to each other by melting an organic polymer having a low melting point of the fibers, a method in which fibers are bonded with a binder, or a method in which these are used in combination. In addition, as a method of melting the fiber having the low melting point organic polymer component on the surface, for example, a method of heating and pressurizing with a calender roll, a method of heating with a hot air dryer, or the like can be used.

Alternatively, the fiber web may be prepared using a direct spinning method. In addition, since the fiber web prepared using the direct spinning method has a mode in which the fibers are bonded to each other, the fiber web may be used as it is as a non-woven fabric without being subjected to a step of bonding the fibers constituting the fiber web.

The porous film or foam can be prepared by, for example, casting a molten organic polymer or inorganic polymer into a mold and molding or subjecting the polymer to a known method.

And when laminating | stacking the raw material mentioned above and preparing a porous body (11), lamination | stacking integration is carried out by the method of only superimposing each material, for example, melting the organic polymer which comprises each material. A method, a method of laminating and integrating each material with a binder, and the like can be employed.

The shape of the porous body (11) can be adjusted as appropriate, and is not limited. For example, the porous body (11) may be processed by punching or cutting into a round shape, an oval shape, a square shape, a rectangular shape, or the like. . Further, for example, pleating may be performed.

  The uneven nonwoven fabric (10) and the porous body (11) obtained as described above are laminated to constitute the sound absorbing material (100).

  As a method of laminating the uneven nonwoven fabric (10) and the porous body (11), a method of simply overlapping the uneven nonwoven fabric (10) and the porous body (11), an uneven nonwoven fabric (10) and / or a porous body (11). For example, a method of melting and integrating the organic polymer constituting the layer, a method of bonding and integrating the uneven nonwoven fabric (10) and the porous body (11) with a binder, and the like can be employed.

  At this time, the lamination direction of the uneven nonwoven fabric (10) laminated on the main surface on the sound source side (W) in the porous body (11) is appropriately adjusted so that the sound absorbing material (100) having excellent sound absorbing performance can be obtained. It is a thing and is not limited. For example, FIG. 1 illustrates an embodiment in which the uneven nonwoven fabric (10) and the porous body (11) are laminated so that the main surface of the uneven nonwoven fabric (10) faces the sound source side (W). The uneven nonwoven fabric (10) and the porous body (11) may be laminated so that the other main surface of the uneven nonwoven fabric (10) faces the side (W).

Moreover, the number of the uneven nonwoven fabrics (10) constituting the sound absorbing material (100) is appropriately prepared so as to obtain the sound absorbing material (100) excellent in sound absorbing performance, and is not limited. For example, FIG. 1 illustrates an embodiment in which one uneven nonwoven fabric (10) is laminated on a porous body (11). For example, like the sound absorbing material (200) illustrated in FIG. A plurality of uneven nonwoven fabrics (10) may be laminated on the porous body (11). In addition, when it is a sound-absorbing material (100) comprised by laminating | stacking several uneven | corrugated nonwoven fabrics (10) on the porous body (11), the lamination direction of each uneven | corrugated nonwoven fabric (10) which comprises a sound-absorbing material (100) is The direction may be the same as or different from the other adjacent uneven nonwoven fabric (10).

  The sound-absorbing material (100) according to the present invention described above can be used as the sound-absorbing material (100) with the uneven nonwoven fabric (10) and the porous body (11) being laminated. Further, for the purpose of reinforcement and improvement in design, a sound absorbing material (100) may be laminated with a cloth, a porous film, a foamed sheet, a net, or the like. When the sound absorbing material (100) needs to be flame retardant, it is preferable to laminate a flame retardant fabric, a porous film, a foamed sheet, a net or the like on the sound absorbing material (100).

In addition, since the sound absorbing material (100) prepared in this way is used by being affixed to the wall surface or inside the device, the main surface on the sound source side (W) of the sound absorbing material (100) or the sound source side (W) An adhesive or a double-sided adhesive tape may be applied to the opposite main surface, or a hook-and-loop fastener may be provided.

And although the sound-absorbing material (100) of the present invention can be used as a flat plate shape, for example, by corrugating, pleating, winding, cutting, punching, punching, partially cutting, etc. The shape can be adjusted and used.

EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but these do not limit the scope of the present invention.

Example 1
(Preparation of spinning device)
In order to prepare a concavo-convex nonwoven fabric using a method of spinning by spinning a spinning solution and a gas flow in parallel, a spinning device having the following configuration was prepared. A schematic cross-sectional view of the spinning start portion in the spinning device used in Example 1 is shown in FIG.

(I) Liquid discharge part (Nl): a short side 0 in a plane perpendicular to the central axis (Ag, not shown in FIG. 5) of the gas columnar hollow part (Hg) (hereinafter referred to as the plane). 725 mm, long side 420 mm rectangular liquid columnar hollow (HI): in the plane, 0.15 mm diameter circular liquid discharge port (EI): in the plane, the long side direction of the liquid discharge part (Nl) And the liquid columnar hollow portion (HI) provided closest to each of the end portions is 44.925 mm apart from each other, and each liquid columnar hollow portion (HI) Each of the adjacent liquid columnar hollow parts (HI) is directed in a direction parallel to the long side direction of the liquid discharge part (Nl) so that the shortest distance to the gas columnar hollow part (Hg) is 0.325 mm. ) 331 exist so that the distance between the centers is 1 mm That

(Ii) Gas columnar hollow part (Hg): slit plane gas discharge part (Ng) having a short side of 0.6 mm and a long side of 420 mm on the plane: a flat plate having a long side of 420 mm and a short side of 3.95 cm on the plane. Is formed in parallel with one side surface of the liquid discharge portion (Nl) and the shortest distance between the liquid discharge portion (Nl) and the flat plate is 0.6 mm. Eg): Corresponding to a slit-shaped portion formed between the liquid discharge portion (Nl) and the flat plate, having a short side of 0.6 mm and a long side of 420 mm, on the plane.

(Iii) Position of liquid discharge port (EI) and gas discharge port (Eg): Arranged at a position where the gas discharge port (Eg) is 5 mm upstream (spinning solution supply side) from the liquid discharge port (EI). to columnar hollow for gas (Hg) cut surface peripheral and columnar hollow for liquid (HI) cleavage plane distance shortest length lines between the outer circumference of the (length of L _1): 0.325 mm
Number of L ₁ per one liquid discharge port (EI): only one liquid discharge direction central axis (AI, not shown in FIG. 5) and gas discharge direction central axis (Ag, not shown in FIG. 5) ):parallel

(Iv) Collector: 10 mesh, metal net (wire diameter: 0.8 mm, through hole shape: square shape with a side length of 1.74 mm)
The moving speed of the collecting body for conveying the collected fibers: 1.6 m / min
Arrangement of collection body: central axis (AI, not shown in FIG. 5) of the liquid columnar hollow part (HI) and central axis (Ag, FIG. 5) of the gas columnar hollow part (Hg) (Not shown) and the collection surface of the collection body are perpendicular to each other, and the shortest distance between the liquid discharge port (EI) and the collection surface of the collection body is 5 cm.
Suction device: A suction box (suction capacity: 43.3 m ³ / min) having a rectangular suction part with a short side of 150 mm and a long side of 260 mm was installed on the back side of the collector when viewed from the spinning start side. .

(Preparation method of uneven nonwoven fabric)
Polypropylene resin (MI = 1500) melted at a temperature of 240 ° C. is discharged in the direction of gravity so as to be 2.1 g / hour per liquid columnar hollow (HI), and a gas discharge port (Eg The air heated to 260 ° C. was discharged so that the discharge volume was 571 Nm ³ / hour / m, and the discharged polypropylene resin was fibrillated.
The nonwoven fabric was formed on the metal net by sucking air with a suction box, causing the fiberized polypropylene resin to fly toward the 10-mesh metal net, and collecting the fiberized polypropylene resin on the metal net. Thereafter, the nonwoven fabric formed on the metal net was collected to prepare a nonwoven fabric having a plurality of convex portions (weight per unit: 21 g / m ² , air permeability: 25.2 cm ³ / cm ² / s).

Furthermore, the cross-sectional photograph of the nonwoven fabric provided with the some convex part prepared in this way was illustrated in FIG.
As a result of analyzing a cross-sectional photograph of the prepared non-woven fabric having a plurality of convex portions, the non-woven fabric having a plurality of convex portions is composed of only a fiber layer having a specific fiber orientation and an irregular fiber orientation. It was a non-woven fabric.
Moreover, the convex part which image | photographed the cross-sectional photograph had the shape described below.
1. Average fiber diameter: 2.5 μm, average fiber diameter CV value: 34%
2. Thickness: 1.1 mm, convex part height: 0.63 mm, concave part thickness: 0.47 mm,
3. The number of fiber layers present inside each convex portion: 7 layers, the number of voids present inside each convex portion: 8, the number of voids having a void area percentage of 6% or more : Two

(Preparation of porous material)
As a porous material, polyethylene terephthalate fiber (fineness: 0.9 dtex, fiber length: 38 mm) is 50% by mass, polyethylene terephthalate fiber (fineness: 6.6 dtex, fiber length: 64 mm) is 20% by mass, low melting point polyethylene terephthalate fiber ( 30% by mass of fineness: 4.4 dtex, fiber length: 51 mm, melting point: 110 ° C.), dispersed on a conveyor by air flow and collected to prepare a fiber web, and then the prepared fiber web is dried with hot air By using the machine, only the low melting point polyethylene terephthalate fiber is melted, and the polyethylene terephthalate fibers are integrated with each other to dry dry nonwoven fabric A (weight: 254 g / m ² , thickness: 5.5 mm, air permeability: 53 cm ³ / cm ² / s) was prepared.

(Manufacturing method of sound absorbing material)
Nylon fiber hot melt nonwoven fabric (manufactured by Japan Vilene Co., Ltd., basis weight: 21 g / m ² , melting point: 108 ° C.) is prepared between the nonwoven fabrics having a plurality of convex portions prepared as described above. The laminate was prepared by interposing five non-woven fabrics having a plurality of convex portions. Further, the laminate and the dry nonwoven fabric A were laminated with the above-described hot melt nonwoven fabric interposed.
At this time, the nonwoven fabrics provided with a plurality of convex portions are laminated so that the lamination direction is the same direction as each other, and on the other main surface side exposed in the nonwoven fabric provided with the plurality of convex portions, A dry nonwoven fabric A was laminated.

And by supplying to a steam generator (Asahi Textile Machine Industry Co., Ltd.) in a state where the laminate and the dry nonwoven fabric A are laminated, the hot melt nonwoven fabric is melted, and the nonwoven fabrics having a plurality of convex portions and the dry type are provided. The nonwoven fabric A was laminated and integrated to prepare a sound-absorbing material (weight per unit: 464 g / m ² , thickness: 11 mm) having the schematic cross section shown in FIG.
The thickness of the sound absorbing material was determined by measuring the shortest distance between the apex of the convex portion and the main surface of the dry nonwoven fabric A exposed to the outside with a caliper.

(Sound absorption measurement)
A circular test piece having a diameter of 29 mm was collected from the sound absorbing material prepared as described above.
Then, the test piece is subjected to a measurement method in accordance with JIS A1405-1: 2007, and the normal incident sound absorption coefficient (%) of the test piece is measured, whereby the frequency (Hz) of the prepared sound absorbing material and the frequency (Hz) are measured. The behavior of sound absorption was measured.
At the time of measurement, the installation direction of the sound absorbing material was adjusted so that the nonwoven fabric having a plurality of convex portions and the dry nonwoven fabric were in order from the sound source side.

(Comparative Example 1)
As a porous material, polyethylene terephthalate fiber (fineness: 0.9 dtex, fiber length: 38 mm) is 50% by mass, polyethylene terephthalate fiber (fineness: 6.6 dtex, fiber length: 64 mm) is 20% by mass, low melting point polyethylene terephthalate fiber ( 30% by mass of fineness: 4.4 dtex, fiber length: 51 mm, melting point: 110 ° C.), dispersed on a conveyor by air flow and collected to prepare a fiber web, and then the prepared fiber web is dried with hot air By using the machine, only the low melting point polyethylene terephthalate fibers are melted, and the polyethylene terephthalate fibers are integrated with each other to form a dry nonwoven fabric B (weight: 532 g / m ² , thickness: 11 mm, air permeability: 31.3 cm ³ / cm ² / s) was prepared.
Then, by using the prepared dry nonwoven fabric B as a sound absorbing material, the sound absorption measurement described in Example 1 is used, and the frequency (Hz) of the sound absorbing material (dry nonwoven fabric B alone) and the behavior of the sound absorption coefficient at the frequency (Hz) are as follows. It was measured.

(Comparative Example 2)
Nylon fiber hot melt nonwoven fabric (manufactured by Japan Vilene Co., Ltd., basis weight: 21 g / m ² , melting point: 108 ° C.) is interposed between the nonwoven fabrics having a plurality of convex portions prepared in Example 1. A laminate was prepared by laminating five nonwoven fabrics having a plurality of convex portions.
At this time, the nonwoven fabrics each having a plurality of convex portions were laminated such that the lamination directions were the same as each other.

And by providing a laminated body to a steam generator (Asahi Textile Machinery Co., Ltd. product), a hot melt nonwoven fabric is melted, and nonwoven fabrics having a plurality of convex portions are laminated and integrated to form a sound absorbing material (weight per unit area) : 210 g / m ² , thickness: 5.4 mm).
The thickness of the sound absorbing material was determined by measuring the shortest distance between the apex of the convex portion of the main surface exposed to the outside and the other main surface exposed to the outside with a caliper.

And the behavior of the sound absorption rate in the frequency (Hz) of the sound absorption material and the said frequency (Hz) was measured by using the prepared sound absorption material for the sound absorption measurement described in Example 1. FIG.
During the measurement, the installation direction of the sound absorbing material was adjusted so that the main surface exposed to the outside faces the sound source side.

(Comparative Example 3)
When the sound absorbing material prepared in Example 1 is subjected to sound absorption measurement, the installation direction of the sound absorbing material is adjusted so that the dry nonwoven fabric A and the nonwoven fabric having a plurality of convex portions are in order from the sound source side. By using the sound absorption measurement described in 1, the frequency of the sound absorbing material (Hz) and the behavior of the sound absorption rate at the frequency (Hz) were measured.

FIG. 8 shows a graph summarizing the results of subjecting each test piece collected from the sound absorbing material of Example 1 and Comparative Example 1-3 to the sound absorption measurement.

As a result of the sound absorption measurement, the sound absorbing material of Example 1 was superior in sound absorbing performance in the frequency band of 500 Hz to 3150 Hz, although the basis weight was lighter than that of the sound absorbing material consisting only of the dry nonwoven fabric B of Comparative Example 1.
And the sound-absorbing material of Example 1 was superior to the sound-absorbing material of Comparative Example 2 in sound absorbing performance in the frequency band of 500 Hz to 3150 Hz.
Furthermore, the sound absorbing material of Example 1 was superior to the sound absorbing material of Comparative Example 3 in sound absorbing performance in the frequency band of 500 Hz to 2000 Hz.

Although the sound absorbing material of Example 1 is lighter in weight than the sound absorbing material of Comparative Example 1, the sound absorbing material of Example 1 is superior in sound absorbing performance for sound waves in a lower frequency band than the sound absorbing material of Comparative Example 1. It was thought that it was because the material was provided with a nonwoven fabric provided with a plurality of convex portions.
As a reason why the sound absorbing material of Example 1 is superior in sound absorbing performance with respect to sound waves in a lower frequency band than the sound absorbing material of Comparative Example 2-3, the sound absorbing material of Example 1 includes a nonwoven fabric and a porous structure having a plurality of convex portions. This is considered to be because the sound absorbing material is formed by laminating bodies, and the nonwoven fabric having a plurality of convex portions and the porous body are laminated in this order from the sound source side of the sound absorbing material.

From the above, the sound-absorbing material of the present invention is a sound-absorbing material that is lightweight and has a sound-absorbing performance that is excellent in sound-absorbing performance for sound waves in a low-frequency band.

The sound absorbing material of the present invention can be used as an industrial material that is required to have sound absorbing performance. Therefore, for example, applications that reduce noise generated inside and outside buildings such as general houses, factories, offices, and hospitals, applications that reduce noise generated inside and outside vehicles such as aircraft, ships, railway vehicles, and automobiles, or industrial The present invention can be suitably used for applications for reducing operation sounds generated inside devices such as robots, processing machines, medical devices, and information device devices (for example, televisions, personal computers, printers, and scanners).

100 ... Sound-absorbing material 10 ... Non-woven fabric (uneven non-woven fabric) having a plurality of convex portions
11 ... porous body W ... sound source side 1, 1a, 1b ... convex portion 2 ... non-existent portion of convex portion (for concave portion)
AA′—A line segment passing through the vertices of two or more convex portions and crossing the concavo-convex nonwoven fabric 3—a fiber layer 4—a void B—the vertex of the convex portion and the other main Straight line t1 connecting the shortest distance to the surface tickness of the uneven nonwoven fabric t2 height t3 of the convex part ... thickness 20 of the concave part ... discharging the spinning stock solution and the gas flow in parallel Spinning device El capable of performing spinning method ... Liquid discharge port Hl ... Liquid columnar hollow portion Nl ... Liquid discharge portion Hvl ... Liquid virtual columnar portion Al ... Discharge direction central axis Eg ... Gas outlet Hg ... Gas columnar hollow portion Ng ... Gas discharge portion Hvg ... Gas virtual columnar portion Ag ... Discharge direction central axis C ... Gas column hollow portion central axis A plane L ₁ perpendicular to the straight line 200 with the shortest distance between the outer peripheries ... the sound absorbing material prepared in Example 1

Claims (1)

A sound absorbing material formed by laminating a nonwoven fabric and a porous body having a plurality of convex portions,
The nonwoven fabric has a convex portion configured by including a plurality of fiber layers, and includes a plurality of voids formed by being surrounded by the fiber layer inside the convex portion,
A sound-absorbing material, wherein the sound-absorbing material is laminated in the order of the nonwoven fabric and the porous body in this order from the sound source side.

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