JP7206564B2 - Laminate and sound absorbing material - Google Patents

Description

The present disclosure relates to laminates and sound absorbing materials.

Polyurethane foams and polyethylene foams containing air layers are used in living environments such as houses and offices, and means of transportation such as aircraft, vehicles, and automobiles for the purpose of blocking noise from the outside and preventing sound from inside from leaking to the outside. Sound absorbing materials made of fibrous materials such as foams, felt, non-woven fabrics, etc. are widely used.

In particular, transportation means such as automobiles require sound absorbing materials that are lighter in weight and have excellent sound absorbing performance. Therefore, as a method of improving sound absorbing performance, layers made of different materials are laminated to form two or three layers. have been proposed (for example, Patent Documents 1 to 5, etc.).

Patent Document 1: JP-A-2002-69823 Patent Document 2: JP-A-2002-161565 Patent Document 3: JP-A-2003-49351 Patent Document 4: JP-A-2014-232281 Patent Document 5: JP-A-2014-232281 2013-139188 publication

However, as in the laminates proposed in Patent Documents 1 to 4, laminates in which layers of different materials are laminated to form two layers exhibit an excellent sound absorption coefficient in a specific frequency region, but the frequency region There is a problem that the sound absorption coefficient is lowered in other than the case.
Moreover, although the laminate proposed in Patent Document 5 exhibits sound absorption in a wide frequency range, it cannot be said that it is still sufficient.

The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide a laminate exhibiting excellent sound absorption over a wide frequency range, and a sound absorbing material including this laminate.

Specific means for solving the above problems are as follows.
<1> A first layer having an air permeability of 1 cc/cm ² /sec or more and less than 30 cc/cm ² /sec, and a second layer having an air permeability of 30 cc/cm ² /sec or more and 1000 cc/cm ² /sec or less. , the third layer having an air permeability of 1 cc/cm ² /sec or more and less than 30 cc/cm ² /sec, and the fourth layer having an air permeability of 30 cc/cm ² /sec or more and 1000 cc/cm ² /sec or less. A laminated body laminated in this order.
<2> The laminate according to <1>, wherein at least one of the first layer and the third layer is a nonwoven fabric, porous film, woven fabric, or foam.
<3> The laminate according to <1> or <2>, wherein at least one of the second layer and the fourth layer is a nonwoven fabric, a woven fabric, or a foam.
<4> The laminate according to any one of <1> to <3>, wherein the thickness of the first layer and the thickness of the third layer are 0.1 mm or more and 2 mm or less, respectively.
<5> The laminate according to any one of <1> to <4>, wherein the second layer and the fourth layer each have a thickness of 10 mm or more and 50 mm or less.

<6> A sound absorbing material comprising the laminate according to any one of <1> to <5>.

INDUSTRIAL APPLICABILITY The present disclosure can provide a laminate exhibiting excellent sound absorption over a wide frequency range, and a sound absorbing material including this laminate.

FIG. 1 is a schematic partial cross-sectional view showing an example of the layer structure of the laminate according to this embodiment. FIG. 2 is a diagram showing the frequency characteristics of the sound absorption coefficients of the sound absorbing materials of Example 1, Comparative Example 1, and Comparative Example 5. FIG. FIG. 3 is a schematic partial cross-sectional view showing an example of the layer structure of a conventional laminate.

In this specification, a numerical range represented by "to" means a range including the numerical values before and after "to" as lower and upper limits.

[Laminate]
An embodiment of the laminate according to the present disclosure will be described below.
The laminate according to the present embodiment includes a first layer having an air permeability of 1 cc/cm ² /sec or more and less than 30 cc/cm ² /sec (hereinafter also referred to as a “low air permeability A layer”), and an air permeability of 30 cc/cm ² /sec or more and 1000 cc/cm ² /sec or less (hereinafter also referred to as “high air permeability B layer”), and a third layer whose air permeability is 1 cc/cm ² /sec or more and less than 30 cc/cm ² /sec. A layer (hereinafter also referred to as "low air permeability C layer") and a fourth layer (hereinafter also referred to as "high air permeability D layer") having an air permeability of 30 cc/cm ² /sec or more and 1000 cc/cm ² /sec or less It is a laminated body laminated in this order.
Layers with an air permeability of 1 cc/cm ² /sec or more and less than 30 cc/cm ² /sec are collectively referred to as “low air permeability layers”, and air permeability is 30 cc/cm ² /sec or more and 1000 cc/cm ² /sec or less. This layer is also collectively referred to as a "highly permeable layer".

Here, the air permeability (cc/cm ² /sec) was measured at 5 points on the sample using a Frazier tester and at a pressure difference of 125 Pa in accordance with JIS L1096 (2010) A method (Frazier method). It is the average value obtained by measuring the amount of air permeation (the amount of air passing through the layer).
When measuring the air permeability of each layer in the laminate, the layer to be measured is separated from the laminate and measured. However, if it is difficult to peel the entire layer to be measured from the laminate, measure the thickness of the layer to be measured, cut out a part of the thickness direction, measure the air permeability of the sample, and measure the layer thickness. The air permeability of the entire layer to be measured may be obtained by converting into a value that takes into account .

FIG. 1 shows an example of the layer structure of the laminate according to this embodiment.
The laminate 10 shown in FIG. 1 has a low air permeability A layer 12, a high air permeability B layer 14, a low air permeability C layer 16, and a high air permeability D layer 18 laminated in this order.
Due to the structure described above, the laminate 10 exhibits excellent sound absorption over a wide frequency range. The reason is presumed as follows.

As a conventional sound absorbing material, for example, as shown in FIG. 3, there is a laminate 110 in which a low air-permeable layer 112 and a high air-permeable layer 114 are laminated to form two layers. In the laminate 110, the two-layer structure described above allows the low air permeability layer 112 to function as a sound absorbing layer and the high air permeability layer 114 to function as a back air layer. High sound absorption performance can be obtained. Specifically, when the surface 115 of the high-permeability layer 114 opposite to the low-permeability layer 112 is the fixed end of the standing wave, the antinode of the standing wave is in the vicinity of the frequency of the low-permeability layer 112 (for example, when the wavelength is high). A high sound absorption coefficient is obtained for a sound that is four times the thickness of the ventilation layer 114 .
However, in the laminate 110, sound other than the specific frequency, especially sound near the frequency at which the node of the standing wave is located at the low-permeability layer 112 (for example, the wavelength is twice the thickness of the high-permeability layer 114). certain sounds), it is difficult to obtain a high sound absorption coefficient.

On the other hand, the laminate 10 is laminated in order of a low air permeability A layer 12, a high air permeability B layer 14, a low air permeability C layer 16, and a high air permeability D layer 18. As shown in FIG. That is, in the laminate 10, in addition to the low air permeability A layer 12 at the same position as the low air permeability layer 112 in the laminate 110, a position corresponding to half the thickness of the high air permeability layer 114 in the laminate 110 also has air permeability. A low air-permeable C layer 16 having a low
Then, similarly to the laminate 110, the low air permeability A layer 12 functions as a sound absorbing layer, so that when the surface 19 of the high air permeability D layer 18 opposite to the low air permeability C layer 16 is the fixed end of the standing wave, the standing wave A high sound absorption coefficient can be obtained for sounds in the vicinity of frequencies where the antinode of the layer 12 is located at the low air permeability A layer 12 . In addition, the low ventilation C layer 16 also functions as a sound absorbing layer, so that the node of the standing wave is located at the low ventilation A layer 12, and the antinode of the standing wave is located at the low ventilation C layer 16. Sound near the frequency ( In other words, a high sound absorption coefficient can be obtained even for sounds for which it is difficult to obtain a high sound absorption coefficient with the laminate 110 .
Thus, the laminate 10 exhibits excellent sound absorption over a wide frequency range.

In addition, when the laminate 110 is used as a sound absorbing material, the thickness of the entire laminate may be restricted depending on the environment in which the sound absorbing material is installed, and the frequency at which a high sound absorption coefficient is obtained depends on the thickness of the high air permeability layer 114. , it may be difficult to obtain a high sound absorption coefficient for the target frequency. However, when the laminate 10 is used as a sound absorbing material, it exhibits excellent sound absorption over a wide frequency range, so it is easy to obtain a high sound absorption coefficient in a target frequency range without changing the thickness of the entire laminate.

In addition, the laminate 10 may be formed by laminating the low air permeability A layer 12, the high air permeability B layer 14, the low air permeability C layer 16, and the high air permeability D layer 18 in this order. It may further have layers (eg, reinforcing layers, adhesive layers, etc.).
Other layers are interlaminar (that is, between the low air permeability A layer 12 and the high air permeability B layer 14, between the high air permeability B layer 14 and the low air permeability C layer 16, and between the low air permeability C layer 16 and the high air permeability D layer 18). It may be provided on the outer surface (that is, the surface of the low air permeable A layer 12 opposite to the high air permeable B layer 14, surface 19).
Moreover, in order to eliminate the dependence of the sound absorption coefficient on the incident direction, a layer having a low air permeability may be further provided on the surface 19 of the laminate 10 .
Furthermore, the laminate 10 may further have a low air permeability layer and a high air permeability layer in addition to the low air permeability A layer 12, the high air permeability B layer 14, the low air permeability C layer 16, and the high air permeability D layer 18. Specifically, for example, a laminate having a 6-layer configuration and a laminate having an 8-layer configuration, in which a combination of a low-permeability layer and a high-permeability layer are further added to the surface 19 side of the high-permeability D layer 18, may be used. Among these, in particular, a 6-layer laminate (not shown) in which a low air permeability A layer, a high air permeability B layer, a low air permeability C layer, a high air permeability D layer, a low air permeability E layer, and a high air permeability F layer are laminated in this order ) is preferred.
The low air permeability E layer is preferably a layer having an air permeability of 1 cc/cm ² /sec or more and less than 30 cc/cm ² /sec like the low air permeability A layer. The basis weight and thickness of the low air permeability E layer are also the same as those of the low air permeability A layer. Further, as the high air permeability F layer, a layer having an air permeability of 30 cc/cm ² /sec or more and 1000 cc/cm ² /sec or less is preferable like the high air permeability B layer. The basis weight and thickness of the highly breathable F layer are also the same as those of the highly breathable B layer.
That is, in the laminate further having the low air permeability layer and the high air permeability layer, the first layer as the low air permeability layer, the second layer as the high air permeability layer, the third layer as the low air permeability layer, A laminate in which a fourth layer that is a high air permeability layer, a fifth layer that is a low air permeability layer, and a sixth layer that is a high air permeability layer are laminated in this order is preferred.

In the laminate 10, the low air permeability A layer 12 and the low air permeability C layer 16 are layers having the same material, the same properties, and the same thickness. Not limited. The materials, properties, and thicknesses of the low air permeability layers (that is, the low air permeability A layer 12 and the low air permeability C layer 16) may be the same or different.
In the laminate 10, the high air permeability B layer 14 and the high air permeability D layer 18 are layers having the same material, the same properties, and the same thickness. Not limited. The materials, properties, and thicknesses of the highly air permeable layers (that is, the highly air permeable B layer 14 and the highly air permeable D layer 18) may be the same or different.
Further, if the air permeability of each layer is within the above range, both the low air permeability layer and the high air permeability layer may be made of the same material (for example, nonwoven fabric, etc.).
As described above, the laminate of the present disclosure exhibits excellent sound absorption over a wide frequency range. Then, the sound absorbing material including the laminate of the present disclosure can be suitably used for automobile applications. In particular, electric vehicles require a wide range of sound absorption properties from low-pitched road noise to high-pitched motor noise, so the laminate of the present disclosure, which has excellent sound absorption over a wide frequency range, is particularly useful.

<Permeability>
The air permeability of the low air permeability A layer 12 and the low air permeability C layer 16 is preferably 1 cc/cm ² /sec or more and less than 30 cc/cm ² /sec, and preferably 3 cc/cm ² /sec or more and 20 cc/cm ² /sec or less. , 5 cc/cm ² /sec or more and 10 cc/cm ² /sec or less.
When the air permeability of the low air permeability A layer 12 and the low air permeability C layer 16 is within the above range, the air permeability of the entire laminate can be kept lower than when it is higher than the above range, and compared to when it is lower than the above range. The function as a sound absorbing layer is easily exhibited.

The air permeability of the high-permeability B layer 14 and the high-permeability D layer 18 is respectively 30 cc/cm ² /sec or more and 1000 cc/cm ² /sec or less, and preferably 40 cc/cm ² /sec or more and 700 cc/cm ² /sec or less. , 50 cc/cm ² /sec or more and 500 cc/cm ² /sec or less.
When the air permeability of the high air permeability B layer 14 and the high air permeability D layer 18 is in the above range, the sound waves reflected in the middle of the sound absorbing material are less than when the air permeability is lower than the above range. The function as a layer is easily exhibited.

The air permeability of the high air permeability B layer 14 is preferably 2 to 100 times the air permeability of the low air permeability A layer 12, more preferably 5 to 50 times, even more preferably 10 to 20 times.
The air permeability of the low air permeable C layer 16 is preferably 0.5 to 2 times the air permeability of the low air permeable A layer 12, more preferably 0.7 to 1.5 times, and 0.9 to 1 0.1 times or less is more preferable.
The air permeability of the high air permeable D layer 18 is preferably 2 to 100 times the air permeability of the low air permeable C layer 16, more preferably 5 to 50 times, and even more preferably 10 to 20 times.
When the air permeability ratio between the layers is within the above range, the roles of the low air permeability layer and the high air permeability layer are exhibited, and the sound absorption coefficient of the laminate increases.

The air permeability of the entire laminate is, for example, 1 cc/cm ² /sec or more and 25 cc/cm ² /sec or less, preferably 2 cc/cm ² /sec or more and 15 cc/cm ² /sec or less, from the viewpoint of improving the sound absorption rate. , 3 cc/cm ² /sec or more and 10 cc/cm ² /sec or less.

<Thickness>
The thicknesses of the low air permeability A layer 12 and the low air permeability C layer 16 are preferably 0.1 mm or more and 2 mm or less, and more preferably 0.1 mm or more and 1 mm or less, from the viewpoint of adjusting the air permeability of the entire laminate to the above range. More preferably 0.1 mm or more and 0.5 mm or less.
The thicknesses of the high-permeability B layer 14 and the high-permeability D layer 18 are set according to the frequency of sound for which the sound absorption coefficient is to be increased, and are not limited. More preferably, it is 10 mm or more and 30 mm or less.
The ratio of the thickness of the high-permeability B layer 14 and the thickness of the high-permeability D layer 18 is not particularly limited, and the low-permeability C layer 16 may be provided at a position where the sound absorption coefficient in the target frequency range is improved. From the viewpoint of making it easier for the low-permeability C layer to absorb sound of frequencies that the low-permeability A layer is difficult to absorb, the thickness of the high-permeability D layer 18 is 0.7 times or more the thickness of the high-permeability B layer 14.1. It is preferably 3 times or less, more preferably 0.9 times or more and 1.1 times or less.
The thickness of the entire laminate is set according to the frequency of sound for which the sound absorption coefficient is to be increased, the environment in which the laminate is installed, and the like, and is not limited, but may be, for example, 20 mm or more and 100 mm or less. The following is preferable, and 30 mm or more and 60 mm or less is more preferable.

<Material>
Materials for the low air permeability layer and the high air permeability layer are not particularly limited as long as the air permeability of each layer is within the above range. shape.

Non-woven fabrics include non-woven fabrics containing organic fibers (for example, resin fibers, etc.) or mixtures thereof, and may be long-fiber non-woven fabrics or short-fiber non-woven fabrics. Nonwoven fabrics include, for example, meltblown nonwoven fabrics, spunbonded nonwoven fabrics, needle punched nonwoven fabrics, thermal bonded nonwoven fabrics, chemical bonded nonwoven fabrics, stitch bonded nonwoven fabrics, spunlace nonwoven fabrics, and the like.
The air permeability of the nonwoven fabric can be controlled, for example, by adjusting the thickness, basis weight, fiber diameter, and the like, and can also be controlled by adjusting the porosity and the like by post-processing such as calendering.

The foam includes a resin material containing air bubbles. Examples of foams include polyurethane foams, polyolefin foams (eg, polyethylene polypropylene foams, etc.), polystyrene foams, acrylic copolymer foams, rubber foams, and the like.
The air permeability of the foam can be controlled by adjusting the thickness, density, closed cell ratio, and the like.

Examples of porous films include microporous films and mesoporous films. Examples of porous films include resin porous films such as films made porous by stretching a resin containing a filler, inorganic porous films such as cement porous films, and films with holes formed by processing such as needle punching. be done.
In addition, the air permeability of the porous film can be controlled by adjusting the thickness, density, pore size, and the like.
Examples of inorganic fibers include glass fibers and carbon fibers.

－Material of low ventilation layer－
Among these, nonwoven fabrics, porous films, woven fabrics, or foams are preferred for the material of the low air-permeable layer, and among these, meltblown nonwoven fabrics, spunbond nonwoven fabrics, glass fiber nonwoven fabrics, and microporous membranes are more preferred, and meltblown nonwoven fabrics are particularly preferred. preferable.

When a meltblown nonwoven fabric is used as the low air permeability layer, the average fiber diameter of the thermoplastic resin fibers constituting the meltblown nonwoven fabric is, for example, 0.1 μm to 10 μm, preferably 1 μm to 10 μm.

Meltblown nonwoven fabric will be described below as an example of the material used for the low air permeability layer.
A meltblown nonwoven fabric is obtained, for example, by ejecting a molten thermoplastic resin composition (that is, a composition containing a thermoplastic resin) from a nozzle, blowing gas to fiberize it, and collecting it.

The thermoplastic resin is not particularly limited as long as it can form a nonwoven fabric, and various known ones can be used.
Examples of thermoplastic resins include polyolefin polymers that are homopolymers or copolymers of α-olefins such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene. coalescence is mentioned.

Examples of olefin polymers include homopolymers of ethylene such as high-pressure low-density polyethylene, linear low-density polyethylene (so-called LLDPE), and high-density polyethylene; ethylene/propylene random copolymers; ethylene/1-butene random Ethylene-based polymers such as ethylene/α-olefin copolymers such as copolymers; propylene homopolymers (so-called polypropylene); propylene/ethylene random copolymers, propylene/ethylene/1-butene random copolymers ( So-called random polypropylene), propylene block copolymers, propylene-based polymers such as propylene/1-butene random copolymers; 1-butene homopolymers, 1-butene/ethylene copolymers, 1-butene/propylene copolymers 1-butene polymer such as coalescence; poly 4-methyl-1-pentene homopolymer, 4-methyl-1-pentene/propylene copolymer, 4-methyl-1-pentene/α-olefin copolymer, etc. 4-methyl-1-pentene polymer; and the like.

In addition to the above polyolefin polymers, thermoplastic resins include polyesters (eg, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), polyamides (eg, nylon-6, nylon-66, polymetaxylene adipamide). etc.), polyvinyl chloride, polyimide, ethylene/vinyl acetate copolymer, polyacrylonitrile, polycarbonate, polystyrene, ionomer, or mixtures thereof.

Among these thermoplastic resins, polyolefin polymers are preferable from the viewpoint of spinning stability during molding, processability, air permeability, flexibility, lightness, and heat resistance of nonwoven fabrics. Among them, propylene-based polymers are more preferable from the viewpoint of heat resistance and lightness. Among the propylene-based polymers, the thermoplastic resin is more preferably a propylene homopolymer or a propylene/α-olefin copolymer.

Propylene-based polymers suitable as thermoplastic resins include, for example, propylene homopolymers having a melting point (Tm) in the range of 125° C. or higher (preferably 130 to 165° C.), or propylene and one or more of them. α-olefins having 2 or more carbon atoms (preferably 2 to 8 carbon atoms) (e.g., ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, etc., but propylene ) is preferred.

The melt flow rate (MFR: ASTM D-1238, 230° C., load 2160 g) of the propylene-based polymer is not particularly limited as long as it can be melt spun. , 50 g/10 minutes to 3000 g/10 minutes, more preferably 100 g/10 minutes to 2000 g/10 minutes.

The thermoplastic resin composition forming the thermoplastic resin fiber contains antioxidants, weather stabilizers, light stabilizers, anti-blocking agents, lubricants, pigments, softeners, and hydrophilic agents as long as the objects of the present disclosure are not impaired. , auxiliaries, water repellents, fillers, antibacterial agents, and other known additives.

The meltblown nonwoven fabric may consist of only fibers formed by the meltblown method, or may contain other fibers. The other fibers may be short fibers or long fibers, and may be crimped or uncrimped fibers. These other fibers can be added for any purpose, such as imparting mechanical properties such as imparting strength, imparting chemical properties, or increasing the weight.
Other fibers include short polyester fibers such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.
The content of other fibers is, for example, 20% by mass or less, preferably 10% by mass or less, and more preferably 5% by mass or less relative to the entire meltblown nonwoven fabric.

－Material of high air permeability layer－
Among these, nonwoven fabrics and foams are preferred for the material of the highly air-permeable layer, and among these, meltblown nonwoven fabrics, spunbond nonwoven fabrics, needle-punched nonwoven fabrics, glass fiber nonwoven fabrics, polyurethane foams, and polyolefin foams are more preferred, and polyurethane foams are more preferred. , meltblown nonwoven fabrics are more preferred, and polyurethane foams are particularly preferred.

When a meltblown nonwoven fabric is used as the highly air-permeable layer, the average fiber diameter of the thermoplastic resin fibers constituting the meltblown nonwoven fabric is, for example, 1 μm to 60 μm, preferably 3 μm to 20 μm.
The components contained in the meltblown nonwoven fabric used for the high air permeability layer are the same as those of the meltblown nonwoven fabric used for the low air permeability layer.

When a foam is used as the highly air-permeable layer, the density of the foam measured according to ASTM D792 A method (submerged water substitution method) is, for example, 9.0 kg/m ³ to 200 kg/m ³ , preferably 10 kg. /m ³ to 200 kg/m ³ , more preferably 20 kg/m ³ to 200 kg/m ³ .
In addition, the closed cell ratio of the foam used for the highly air-permeable layer measured according to C method of ASTM D2856 is, for example, 0% or more and less than 60%, preferably 0 to 55%, more preferably 0 to 50%. %. In other words, it is preferable that the foam used for the highly air-permeable layer has an open cell structure from the viewpoint of increasing the air permeability of the highly breathable layer and the sound absorption coefficient of the laminate.
The average cell diameter (average cell diameter) of the foam used for the high air layer is, for example, 10 μm or more and 2000 μm or less, preferably 300 μm or more and 2000 μm or less, more preferably 600 μm or more and 2000 μm or less.

The polyurethane foam used for the highly air-permeable layer will be described below.
Polyurethane foams can be obtained, for example, by reacting a composition containing polyisocyanate, polyol, blowing agent, and optionally other components.
Examples of polyisocyanates include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, derivatives thereof, and the like. One type may be used alone, or two or more types may be used in combination. .

Aliphatic polyisocyanates include, for example, trimethylene diisocyanate, tetramethylene diisocyanate (TMDI), pentamethylene diisocyanate (PDI), hexamethylene diisocyanate (HDI), 1,2-, 2,3- or 1,3-butylene diisocyanate. , 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate.

Alicyclic polyisocyanates include, for example, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate, IPDI), dicyclohexylmethane diisocyanate (e.g., 4,4′-, 2,4′-, or 2,2′-dicyclohexylmethane diisocyanate or mixtures thereof, H12MDI), bis(isocyanatomethyl)norbornane (e.g. 2,5- or 2,6-bis(isocyanatomethyl)norbornane or mixtures thereof, NBDI), 1 ,3-cyclopentane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate and the like.

Examples of aromatic polyisocyanates include xylylene diisocyanate (eg, 1,3- or 1,4-xylylene diisocyanate or mixtures thereof, XDI), tetramethylxylylene diisocyanate (eg, 1,3- or 1,4 -tetramethylxylylene diisocyanate or mixtures thereof, TMXDI), ω,ω'-diisocyanato-1,4-diethylbenzene, diphenylmethane diisocyanate (for example 4,4'-, 2,4'- or 2,2'-diphenylmethane diisocyanate or mixtures thereof, MDI), tolylene diisocyanate (for example, 2,4- or 2,6-tolylene diisocyanate or mixtures thereof, TDI), 3,3′-dimethoxybiphenyl-4,4′-diisocyanate, 1, 5-naphthalene diisocyanate (NDI), phenylene diisocyanate (m- or p-phenylene diisocyanate or a mixture thereof), 4,4'-diphenyl diisocyanate, 4,4'-diphenyl ether diisocyanate and the like.

Derivatives of polyisocyanates include, for example, multimers (e.g., dimers, trimers (e.g., isocyanurate modified products, iminooxadiazinedione modified products), pentamers, heptamers, etc. of the above polyisocyanates. ), an allophanate modified product (e.g., the above polyisocyanate and an allophanate modified product produced by the reaction of a low-molecular-weight polyol described later), a polyol-modified product (e.g., the polyisocyanate generated by the reaction with a low-molecular-weight polyol described later. Polyol modified product (alcohol adduct) etc.), biuret modified product (e.g., biuret modified product formed by reaction of the above polyisocyanate with water or amines), urea modified product (e.g., the above polyisocyanate and diamine urea modified product produced by reaction with), oxadiazinetrione modified product (for example, oxadiazinetrione produced by reaction of the above polyisocyanate with carbon dioxide), carbodiimide modified product (decarboxylation of the above polyisocyanate carbodiimide-modified products produced by condensation reaction, etc.), uretdione-modified products, uretonimine-modified products, polymethylene polyphenyl polyisocyanates (eg, crude MDI, polymeric MDI), and the like.

Polyol components include high-molecular-weight polyols and low-molecular-weight polyols, and may be used alone or in combination of two or more.
A high molecular weight polyol is a compound having a number average molecular weight of 1000 or more and having two or more hydroxyl groups. Examples include acrylic polyols and vinyl monomer-modified polyols.

Low-molecular-weight polyols are compounds having a number average molecular weight of less than 1000 and having two or more hydroxyl groups. 1,2-butylene glycol, 1,5-pentanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,2-trimethylpentanediol, 3,3- Dimethylolheptane, alkane (C7-20) diols, cyclohexanedimethanol (eg 1,3- or 1,4-cyclohexanedimethanol or mixtures thereof), hydrogenated bisphenol A, 1,4-dihydroxy-2-butene , 2,6-dimethyl-1-octene-3,8-diol, bisphenol A, diethylene glycol, triethylene glycol, dihydric alcohols such as dipropylene glycol; trihydric alcohols such as glycerin, trimethylolpropane, triisopropanolamine; Tetramethylolmethane (pentaerythritol), tetrahydric alcohols such as diglycerin; pentahydric alcohols such as xylitol; hexahydric alcohols such as sorbitol, mannitol, allitol, iditol, dulcitol, altritol, inositol, dipentaerythritol; polyhydric alcohols such as heptahydric alcohols; octahydric alcohols such as sucrose;
Low-molecular-weight polyols also include, for example, low-molecular-weight (number-average molecular weight less than 1,000) polyether polyols, polyester polyols, and polyether ester polyols.

Examples of foaming agents include water, halogen-substituted aliphatic hydrocarbon foaming agents (e.g., trichlorofluoromethane, dichlorodifluoromethane, trichloroethane, trichloroethylene, tetrachloroethylene, methylene chloride, trichlorotrifluoroethane, dibromotetrafluoroethane, tetrachloride carbon etc.).
A foaming agent can be used individually or in combination of 2 or more types.

The composition for obtaining the polyurethane foam may contain other components such as a catalyst.
Examples of catalysts include triethylamine, triethylenediamine, N-methylmorpholine, bis(2-dimethylaminoethyl)ether, tris(dimethylaminopropyl)hexahydro-S-triazine, 1,4-diazabicyclo[2.2.2 ] tertiary amines such as octane; quaternary ammonium salts such as tetraethylhydroxyammonium; imidazoles such as imidazole and 2-ethyl-4-methylimidazole; In addition to the above amine-based catalysts, examples of catalysts include organotin compounds such as tin acetate, tin octylate, dibutyltin dilaurate, and dibutyltin chloride; organolead compounds such as lead octylate and lead naphthenate; Organometallic catalysts such as organonickel compounds such as nickel are also included.
A catalyst can be used individually or in combination of 2 or more types.

Other components contained in the composition for obtaining the polyurethane foam include, in addition to the above catalysts, for example, foam stabilizers, flame retardants, viscosity reducers, anti-aging agents, pigments and the like.

<Method for manufacturing laminate>
In the production of the laminate, each layer may be formed separately and then laminated, or each layer may be formed sequentially while laminating.
For example, when manufacturing the laminate 10, after forming the low air permeability A layer 12, the high air permeability B layer 14, the low air permeability C layer 16, and the high air permeability D layer 18, the obtained layers may be laminated. Further, for example, after forming the low air permeability A layer 12, the high air permeability B layer 14 is formed on the low air permeability A layer 12, and similarly the low air permeability C layer 16 and the high air permeability D layer 18 may be sequentially formed. good.

The method of bonding between layers varies depending on the material of the layers. heat embossing, ultrasonic fusion, etc.), mechanical entanglement (eg, needle punch, water jet, etc.), and the like.
In addition, the laminate may be subjected to secondary processing such as printing, coating, heat treatment, shaping processing, etc., within a range that does not impair the purpose of the present disclosure.

<Application of laminate>
As described above, the laminate 10 exhibits excellent sound absorption over a wide frequency range, and is particularly suitable for use as a sound absorbing material. good.

[Sound absorbing material]
The sound absorbing material according to this embodiment includes the laminate described above. Specifically, for example, the sound absorbing material including the laminate 10 shown in FIG. It may be a sound absorbing material. In the sound absorbing material including the laminate 10, excellent sound absorption over a wide frequency range can be obtained by arranging the laminate 10 so that the low air permeability A layer 12 side of the laminate 10 is on the sound incident side.

EXAMPLES Hereinafter, the present disclosure will be described more specifically based on Examples, but the present disclosure is not limited to these Examples.

Physical properties and the like in Examples, Reference Examples and Comparative Examples were measured by the following methods.
(1) basis weight (g/m ² )
Ten samples for fabric weight measurement of 100 mm in the machine direction (MD)×100 mm in the transverse direction (CD) were cut out, and an average value was calculated from these ten samples for fabric weight measurement.

(2) Thickness (mm)
The thickness of each of the 10 samples for basis weight measurement was measured at a total of 5 points in the center and at the four corners, and the average value of 50 points in total was calculated. A thickness gauge with a load of 7 gf/cm ² (probe diameter 50 mmφ) was used to measure the thickness.

(3) air permeability (cc/cm ² /sec)
A Frazier tester was used to measure the permeation rate at a pressure difference of 125 Pa in accordance with JIS L1096 at a total of 5 points in the center and four corners of the measurement sample (100 mm x 100 mm), and the average value was obtained.

(4) Sound absorption coefficient (sound absorption performance)
A circular test piece of 29 mmφ was taken from the obtained laminate, and a flat surface was measured on the test piece at a frequency of 1000 to 6400 Hz in accordance with ASTM E 1050 using a normal incident sound absorption coefficient measuring device [TYPE 4206 manufactured by Brüel & Kea]. The normal incidence sound absorption coefficient was measured when sound waves were vertically incident. The sound absorption coefficients at 1000 Hz and 5000 Hz were obtained from the obtained sound absorption coefficient curves at 1000 to 6400 Hz. Note that the sound absorption coefficients shown in Table 1 are values where "1" is set when all incident sounds are absorbed.

(5) Average fiber diameter of nonwoven fabric (μm)
The resulting nonwoven fabric was photographed using an electron microscope "S-3500N" manufactured by Hitachi, Ltd. at a magnification of 1000 times. diameter) was measured, and the average fiber diameter was calculated based on the number average.

(6) Foam density (kg/m ³ )
The density of the foam was measured in accordance with ASTM D792 method A (water substitution method).

[Example 1]
<Preparation for each layer>
As the high air permeability B layer 14 (second layer) and the high air permeability D layer 18 (fourth layer) of the laminate 10, foam-molded urethane sheets (manufactured by INOAC, product name: ECS10, density: 22 kg/m ³ ) were used. each prepared. The basis weight of the urethane sheets (“second layer” and “fourth layer” in Table 1) (“basis weight” in Table 1, unit: g/m ² ), air permeability (“air permeability” in Table 1, Table 1 shows the thickness ("thickness" in Table ¹ , unit: mm).
As the low air permeability A layer 12 (first layer) and the low air permeability C layer 16 (third layer) of the laminate 10, meltblown nonwoven fabrics (average fiber diameter: 1 μm) were produced as follows. The obtained meltblown nonwoven fabric ("first layer" and "third layer" in Table 1) has a basis weight ("basis weight" in Table 1, unit: g / m ² ), air permeability ("air permeability ", unit: cc/cm ² /sec) and thickness ("thickness" in Table 1, unit: mm) are shown in Table 1.

A propylene homopolymer (melt flow rate: 1550 g/10 min, melting point: 157° C., hereinafter referred to as “PP”) was used as the thermoplastic resin, and the above thermoplastic resin was used as it was as a thermoplastic resin composition.
A meltblown nonwoven fabric was obtained using a meltblown nonwoven fabric manufacturing apparatus equipped with a meltblown spinning nozzle having a nozzle hole diameter of 0.20 mm as a nozzle. Specifically, using this meltblown nonwoven fabric manufacturing apparatus, a thermoplastic resin composition is extruded at 300 ° C., and heated air (300 ° C., 350 Nm ³ /m / h) blown from both sides of the spinning nozzle is used to extrude the fiber. After attenuating and solidifying, the fibers were collected at a distance of 20 cm from the spinning nozzle to obtain a meltblown nonwoven fabric.

<Production of laminate>
A spray adhesive (manufactured by 3M, product name: Spray Glue 55) was used to bond the prepared layers.
Specifically, first, an adhesive was sprayed on the surface of a urethane sheet to be the highly air permeable layer D 18 (fourth layer), and a meltblown nonwoven fabric to be the low air permeable layer C 16 (third layer) was overlaid. Similarly, an adhesive was sprayed on the surface of the meltblown nonwoven fabric for the low air permeability C layer 16 (third layer), and a urethane sheet for the high air permeability B layer 14 (second layer) was layered. Further, an adhesive was sprayed on the surface of the urethane sheet to be the high air permeability B layer 14 (second layer), and a meltblown nonwoven fabric to be the low air permeability A layer 12 (first layer) was overlaid.

As described above, a laminate of Example 1 in which four layers were laminated via an adhesive was obtained.
The basis weight (“basis weight” in Table 1, unit: g/m ² ) and air permeability (“air permeability” in Table 1, unit: cc/cm) of the entire laminate obtained (“total” in Table 1) ² /sec) and thickness ("thickness" in Table 1, unit: mm) are shown in Table 1.
The sound absorption performance of the obtained laminate is shown in Table 1 ("sound absorption coefficient" in Table 1).
Furthermore, FIG. 2 shows the frequency dependence of the sound absorption coefficient in the laminate of Example 1. As shown in FIG. The vertical axis of the graph shown in FIG. 2 is the sound absorption coefficient, and the horizontal axis is the frequency (Hz).

[Example 2]
As the high air permeability B layer 14 (second layer) and the high air permeability D layer 18 (fourth layer) of the laminate 10, needle-punched nonwoven fabrics (average fiber diameter: 30 μm) obtained by the following method are used instead of urethane sheets. A laminate was obtained in the same manner as in Example 1, except that . The basis weight ("basis weight" in Table 1, unit: g/m ² ) and air permeability (" Table 1 shows the air permeability, unit: cc/cm ² /sec, and thickness (“thickness” in Table 1, unit: mm).
The basis weight (“basis weight” in Table 1, unit: g/m ² ) and air permeability (“air permeability” in Table 1, unit: cc/cm) of the entire laminate obtained (“total” in Table 1) ² /sec) and thickness ("thickness" in Table 1, unit: mm) are shown in Table 1.
The sound absorption performance of the obtained laminate is shown in Table 1 ("sound absorption coefficient" in Table 1).
The needle-punched nonwoven fabric was produced as follows.
A needle-punched nonwoven fabric was obtained by forming polyethylene terephthalate fibers (hereinafter also referred to as “PET short fibers”) having an average fiber diameter of 20 μm and an average fiber length of 50 mm into a nonwoven fabric sheet with a needle punch machine.

[Example 3]
The high air permeability B layer (second layer), the high air permeability D layer (fourth layer), and the high air permeability F layer (sixth layer) in the six-layer laminate have a thickness of 13 mm and a basis weight of 286 g / m ² , and a urethane sheet (manufactured by INOAC, product name: ECS) having an air permeability of 166 cc/cm ² /sec were prepared.
The low-permeability A layer (first layer), the low-permeability C layer (third layer), and the low-permeability E layer (fifth layer) in the six-layer laminate have a thickness of 0.1 mm and a basis weight of 10 g / A meltblown nonwoven fabric having an air permeability of ^{7 cc/cm 2 /} sec was prepared. This meltblown nonwoven fabric is the same as the first and third layers of Example 1.
In the same manner as in Example 1, the 1st to 6th layers were laminated in order via an adhesive to obtain a laminate consisting of a total of 6 layers. The sound absorption performance of the obtained laminate of Example 3 is shown in Table 1 ("sound absorption coefficient" in Table 1).

[Comparative Example 1]
As the high air permeability layer 114 (second layer) of the laminate 110 shown in FIG. 3, a urethane sheet (manufactured by INOAC, product name: ECS) similar to the high air permeability layer of Example 1 except for the thickness and basis weight was prepared. The basis weight of the urethane sheet (“second layer” in Table 1) (“basis weight” in Table 1, unit: g/m ² ), air permeability (“air permeability” in Table 1, unit: cc/cm ² /sec) and thickness ("thickness" in Table 1, unit: mm) are shown in Table 1.
Also, as the low air permeability layer 112 (first layer) of the laminate 110 shown in FIG. The obtained meltblown nonwoven fabric (“first layer” in Table 1) has a basis weight (“basis weight” in Table 1, unit: g/m ² ), air permeability (“air permeability” in Table 1, unit: cc/ cm ² /sec) and thickness (“thickness” in Table 1, unit: mm) are shown in Table 1.

Two layers were bonded in the same manner as in Example 1.
The basis weight (“basis weight” in Table 1, unit: g/m ² ) and air permeability (“air permeability” in Table 1, unit: cc/cm) of the entire laminate obtained (“total” in Table 1) ² /sec) and thickness ("thickness" in Table 1, unit: mm) are shown in Table 1. Note that the slanted lines in Table 1 indicate that there is no applicable layer, and the same applies hereinafter.
The sound absorption performance of the obtained laminate is shown in Table 1 ("sound absorption coefficient" in Table 1).
Further, FIG. 2 shows the frequency dependence of the sound absorption coefficient in the laminate of Comparative Example 1. As shown in FIG.

[Comparative Example 2]
As the low air permeability layer 112 (first layer) of the laminate 110 shown in FIG. got a body
The obtained meltblown nonwoven fabric (“first layer” in Table 1) has a basis weight (“basis weight” in Table 1, unit: g/m ² ), air permeability (“air permeability” in Table 1, unit: cc/ cm ² /sec) and thickness (“thickness” in Table 1, unit: mm) are shown in Table 1.
In addition, the basis weight ("basis weight" in Table 1, unit: g/m ² ) and air permeability ("breathability" in Table 1, unit: cc /cm ² /sec) and thickness (“thickness” in Table 1, unit: mm) are shown in Table 1.
Furthermore, the sound absorption performance of the obtained laminate is shown in Table 1 ("sound absorption coefficient" in Table 1).

[Comparative Example 3]
As the high air permeability layer 114 (second layer) of the laminate 110 shown in FIG. A laminate was obtained.
The obtained needle-punched nonwoven fabric (“second layer” in Table 1) has a basis weight (“basis weight” in Table 1, unit: g/m ² ) and air permeability (“air permeability” in Table 1, unit: cc). /cm ² /sec) and thickness (“thickness” in Table 1, unit: mm) are shown in Table 1.
In addition, the basis weight ("basis weight" in Table 1, unit: g/m ² ) and air permeability ("breathability" in Table 1, unit: cc /cm ² /sec) and thickness (“thickness” in Table 1, unit: mm) are shown in Table 1.
Furthermore, the sound absorption performance of the obtained laminate is shown in Table 1 ("sound absorption coefficient" in Table 1).

[Comparative Example 4]
A single-layer nonwoven fabric sound absorbing material (manufactured by 3M, product name: TAI4027) was used as a single layer.
The basis weight ("basis weight" in Table 1, unit: g/ ^m2 ) and air permeability ("air permeability" in Table 1, unit: cc/cm) in the entire single-layer nonwoven fabric sound absorbing material ("total" in Table 1) ² /sec) and thickness ("thickness" in Table 1, unit: mm) are shown in Table 1.
Furthermore, the sound absorption performance of the obtained laminate is shown in Table 1 ("sound absorption coefficient" in Table 1).

[Comparative Example 5]
Two layers of a single-layer nonwoven fabric sound absorbing material (manufactured by 3M, product name: TAI4027) were used, and the two layers were adhered in the same manner as in Example 1 to obtain a laminate.
The basis weight (“basis weight” in Table 1, unit: g/m ² ) and air permeability (“air permeability” in Table 1, unit: cc/cm) of the entire laminate obtained (“total” in Table 1) ² /sec) and thickness ("thickness" in Table 1, unit: mm) are shown in Table 1.
The sound absorption performance of the obtained laminate is shown in Table 1 ("sound absorption coefficient" in Table 1).
Furthermore, FIG. 2 shows the frequency dependence of the sound absorption coefficient in the laminate of Comparative Example 5. As shown in FIG.

As shown in Table 1 and FIG. 2, it can be seen that the examples exhibit superior sound absorption over a wider frequency range than the comparative examples.

Since the laminate of the present disclosure exhibits excellent sound absorption over a wide frequency range, it can be used in transportation vehicles such as automobiles, trains, ships, and aircraft; electrical appliances such as machines; OA equipment such as copiers, facsimiles, personal computers, and printers; homes such as wall materials, ceiling materials, and floor materials; Among them, in applications where the thickness of the entire sound absorbing material is limited (for example, automobiles, etc.), the laminate of the present disclosure is particularly useful because it can improve sound absorption over a wide frequency range without changing the overall thickness. . In addition, since electric vehicle applications require a wide range of sound absorption properties from low-pitched road noise to high-pitched motor noise, the laminate of the present disclosure, which has excellent sound absorption over a wide frequency range, is particularly useful.

The disclosure of Japanese Patent Application No. 2017-072285 filed on March 31, 2017 is incorporated herein by reference in its entirety.
All publications, patent applications and technical standards mentioned herein are to the same extent as if each individual publication, patent application and technical standard were specifically and individually noted to be incorporated by reference. incorporated herein by reference.

10 laminate, 12 low air permeability A layer, 14 high air permeability B layer, 16 low air permeability C layer, 18 high air permeability D layer, 19 surface

Claims (4)

a first layer made of a nonwoven fabric and having an air permeability of 1 cc/cm ² /sec or more and less than 30 cc/cm ² /sec;
a second layer having an air permeability of 30 cc/cm ² /sec or more and 1000 cc/cm ² /sec or less, and an air permeability of 5 times or more that of the first layer;
The third layer is made of a nonwoven fabric, has an air permeability of 1 cc/cm ² /sec or more and less than 30 cc/cm ² /sec, and has an air permeability of 0.5 times or more and 2 times or less that of the first layer. a layer of
a fourth layer having an air permeability of 30 cc/cm ² /sec or more and 1000 cc/cm ² /sec or less, and an air permeability of 5 times or more that of the third layer;
are stacked in this order,
A laminate in which the second layer and the fourth layer are polyurethane foams. The laminate according to claim 1, wherein the thickness of the first layer and the thickness of the third layer are 0.1 mm or more and 2 mm or less, respectively. 3. The laminate according to claim 1, wherein the thickness of the second layer and the thickness of the fourth layer are 10 mm or more and 50 mm or less, respectively. A sound absorbing material comprising the laminate according to any one of claims 1 to 3.

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